Adding upstream version 1.1.0.upstream/1.1.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

41 files changed, 42565 insertions, 0 deletions

diff --git a/src/.gitignore b/src/.gitignore
new file mode 100644
index 0000000..0473afb
--- /dev/null
+++ b/src/.gitignore
@@ -0,0 +1,6 @@
+*.o
+*.a
+/libbpf.pc
+/libbpf.so*
+/staticobjs
+/sharedobjs
diff --git a/src/Makefile b/src/Makefile
new file mode 100644
index 0000000..d535f81
--- /dev/null
+++ b/src/Makefile
@@ -0,0 +1,183 @@
+# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+ifeq ($(V),1)
+	Q =
+	msg =
+else
+	Q = @
+	msg = @printf '  %-8s %s%s\n' "$(1)" "$(2)" "$(if $(3), $(3))";
+endif
+
+LIBBPF_MAJOR_VERSION := 1
+LIBBPF_MINOR_VERSION := 1
+LIBBPF_PATCH_VERSION := 0
+LIBBPF_VERSION := $(LIBBPF_MAJOR_VERSION).$(LIBBPF_MINOR_VERSION).$(LIBBPF_PATCH_VERSION)
+LIBBPF_MAJMIN_VERSION := $(LIBBPF_MAJOR_VERSION).$(LIBBPF_MINOR_VERSION).0
+LIBBPF_MAP_VERSION := $(shell grep -oE '^LIBBPF_([0-9.]+)' libbpf.map | sort -rV | head -n1 | cut -d'_' -f2)
+ifneq ($(LIBBPF_MAJMIN_VERSION), $(LIBBPF_MAP_VERSION))
+$(error Libbpf release ($(LIBBPF_VERSION)) and map ($(LIBBPF_MAP_VERSION)) versions are out of sync!)
+endif
+
+define allow-override
+  $(if $(or $(findstring environment,$(origin $(1))),\
+            $(findstring command line,$(origin $(1)))),,\
+    $(eval $(1) = $(2)))
+endef
+
+$(call allow-override,CC,$(CROSS_COMPILE)cc)
+$(call allow-override,LD,$(CROSS_COMPILE)ld)
+
+TOPDIR = ..
+
+INCLUDES := -I. -I$(TOPDIR)/include -I$(TOPDIR)/include/uapi
+ALL_CFLAGS := $(INCLUDES)
+
+SHARED_CFLAGS += -fPIC -fvisibility=hidden -DSHARED
+
+CFLAGS ?= -g -O2 -Werror -Wall -std=gnu89
+ALL_CFLAGS += $(CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 $(EXTRA_CFLAGS)
+ALL_LDFLAGS += $(LDFLAGS) $(EXTRA_LDFLAGS)
+
+ifdef NO_PKG_CONFIG
+	ALL_LDFLAGS += -lelf -lz
+else
+	PKG_CONFIG ?= pkg-config
+	ALL_CFLAGS += $(shell $(PKG_CONFIG) --cflags libelf zlib)
+	ALL_LDFLAGS += $(shell $(PKG_CONFIG) --libs libelf zlib)
+endif
+
+OBJDIR ?= .
+SHARED_OBJDIR := $(OBJDIR)/sharedobjs
+STATIC_OBJDIR := $(OBJDIR)/staticobjs
+OBJS := bpf.o btf.o libbpf.o libbpf_errno.o netlink.o \
+	nlattr.o str_error.o libbpf_probes.o bpf_prog_linfo.o \
+	btf_dump.o hashmap.o ringbuf.o strset.o linker.o gen_loader.o \
+	relo_core.o usdt.o
+SHARED_OBJS := $(addprefix $(SHARED_OBJDIR)/,$(OBJS))
+STATIC_OBJS := $(addprefix $(STATIC_OBJDIR)/,$(OBJS))
+
+STATIC_LIBS := $(OBJDIR)/libbpf.a
+ifndef BUILD_STATIC_ONLY
+	SHARED_LIBS := $(OBJDIR)/libbpf.so \
+		       $(OBJDIR)/libbpf.so.$(LIBBPF_MAJOR_VERSION) \
+		       $(OBJDIR)/libbpf.so.$(LIBBPF_VERSION)
+	VERSION_SCRIPT := libbpf.map
+endif
+
+HEADERS := bpf.h libbpf.h btf.h libbpf_common.h libbpf_legacy.h \
+	   bpf_helpers.h bpf_helper_defs.h bpf_tracing.h \
+	   bpf_endian.h bpf_core_read.h skel_internal.h libbpf_version.h \
+	   usdt.bpf.h
+UAPI_HEADERS := $(addprefix $(TOPDIR)/include/uapi/linux/,\
+			    bpf.h bpf_common.h btf.h)
+
+PC_FILE := $(OBJDIR)/libbpf.pc
+
+INSTALL = install
+
+DESTDIR ?=
+
+HOSTARCH = $(firstword $(subst -, ,$(shell $(CC) -dumpmachine)))
+ifeq ($(filter-out %64 %64be %64eb %64le %64el s390x, $(HOSTARCH)),)
+	LIBSUBDIR := lib64
+else
+	LIBSUBDIR := lib
+endif
+
+# By default let the pc file itself use ${prefix} in includedir/libdir so that
+# the prefix can be overridden at runtime (eg: --define-prefix)
+ifndef LIBDIR
+	LIBDIR_PC := $$\{prefix\}/$(LIBSUBDIR)
+else
+	LIBDIR_PC := $(LIBDIR)
+endif
+PREFIX ?= /usr
+LIBDIR ?= $(PREFIX)/$(LIBSUBDIR)
+INCLUDEDIR ?= $(PREFIX)/include
+UAPIDIR ?= $(PREFIX)/include
+
+TAGS_PROG := $(if $(shell which etags 2>/dev/null),etags,ctags)
+
+all: $(STATIC_LIBS) $(SHARED_LIBS) $(PC_FILE)
+
+$(OBJDIR)/libbpf.a: $(STATIC_OBJS)
+	$(call msg,AR,$@)
+	$(Q)$(AR) rcs $@ $^
+
+$(OBJDIR)/libbpf.so: $(OBJDIR)/libbpf.so.$(LIBBPF_MAJOR_VERSION)
+	$(Q)ln -sf $(^F) $@
+
+$(OBJDIR)/libbpf.so.$(LIBBPF_MAJOR_VERSION): $(OBJDIR)/libbpf.so.$(LIBBPF_VERSION)
+	$(Q)ln -sf $(^F) $@
+
+$(OBJDIR)/libbpf.so.$(LIBBPF_VERSION): $(SHARED_OBJS)
+	$(call msg,CC,$@)
+	$(Q)$(CC) -shared -Wl,--version-script=$(VERSION_SCRIPT) \
+		  -Wl,-soname,libbpf.so.$(LIBBPF_MAJOR_VERSION) \
+		  $^ $(ALL_LDFLAGS) -o $@
+
+$(OBJDIR)/libbpf.pc: force
+	$(Q)sed -e "s|@PREFIX@|$(PREFIX)|" \
+		-e "s|@LIBDIR@|$(LIBDIR_PC)|" \
+		-e "s|@VERSION@|$(LIBBPF_VERSION)|" \
+		< libbpf.pc.template > $@
+
+$(STATIC_OBJDIR) $(SHARED_OBJDIR):
+	$(call msg,MKDIR,$@)
+	$(Q)mkdir -p $@
+
+$(STATIC_OBJDIR)/%.o: %.c | $(STATIC_OBJDIR)
+	$(call msg,CC,$@)
+	$(Q)$(CC) $(ALL_CFLAGS) $(CPPFLAGS) -c $< -o $@
+
+$(SHARED_OBJDIR)/%.o: %.c | $(SHARED_OBJDIR)
+	$(call msg,CC,$@)
+	$(Q)$(CC) $(ALL_CFLAGS) $(SHARED_CFLAGS) $(CPPFLAGS) -c $< -o $@
+
+define do_install
+	$(call msg,INSTALL,$1)
+	$(Q)if [ ! -d '$(DESTDIR)$2' ]; then		\
+		$(INSTALL) -d -m 755 '$(DESTDIR)$2';	\
+	fi;
+	$(Q)$(INSTALL) $(if $3,-m $3,) $1 '$(DESTDIR)$2'
+endef
+
+# Preserve symlinks at installation.
+define do_s_install
+	$(call msg,INSTALL,$1)
+	$(Q)if [ ! -d '$(DESTDIR)$2' ]; then		\
+		$(INSTALL) -d -m 755 '$(DESTDIR)$2';	\
+	fi;
+	$(Q)cp -fR $1 '$(DESTDIR)$2'
+endef
+
+install: all install_headers install_pkgconfig
+	$(call do_s_install,$(STATIC_LIBS) $(SHARED_LIBS),$(LIBDIR))
+
+install_headers:
+	$(call do_install,$(HEADERS),$(INCLUDEDIR)/bpf,644)
+
+# UAPI headers can be installed by a different package so they're not installed
+# in by install rule.
+install_uapi_headers:
+	$(call do_install,$(UAPI_HEADERS),$(UAPIDIR)/linux,644)
+
+install_pkgconfig: $(PC_FILE)
+	$(call do_install,$(PC_FILE),$(LIBDIR)/pkgconfig,644)
+
+clean:
+	$(call msg,CLEAN)
+	$(Q)rm -rf *.o *.a *.so *.so.* *.pc $(SHARED_OBJDIR) $(STATIC_OBJDIR)
+
+.PHONY: cscope tags force
+cscope:
+	$(call msg,CSCOPE)
+	$(Q)ls *.c *.h > cscope.files
+	$(Q)cscope -b -q -f cscope.out
+
+tags:
+	$(call msg,CTAGS)
+	$(Q)rm -f TAGS tags
+	$(Q)ls *.c *.h | xargs $(TAGS_PROG) -a
+
+force:
diff --git a/src/bpf.c b/src/bpf.c
new file mode 100644
index 0000000..9aff98f
--- /dev/null
+++ b/src/bpf.c
@@ -0,0 +1,1165 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * common eBPF ELF operations.
+ *
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License (not later!)
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not,  see <http://www.gnu.org/licenses>
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <memory.h>
+#include <unistd.h>
+#include <asm/unistd.h>
+#include <errno.h>
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <linux/kernel.h>
+#include <limits.h>
+#include <sys/resource.h>
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+
+/*
+ * When building perf, unistd.h is overridden. __NR_bpf is
+ * required to be defined explicitly.
+ */
+#ifndef __NR_bpf
+# if defined(__i386__)
+#  define __NR_bpf 357
+# elif defined(__x86_64__)
+#  define __NR_bpf 321
+# elif defined(__aarch64__)
+#  define __NR_bpf 280
+# elif defined(__sparc__)
+#  define __NR_bpf 349
+# elif defined(__s390__)
+#  define __NR_bpf 351
+# elif defined(__arc__)
+#  define __NR_bpf 280
+# elif defined(__mips__) && defined(_ABIO32)
+#  define __NR_bpf 4355
+# elif defined(__mips__) && defined(_ABIN32)
+#  define __NR_bpf 6319
+# elif defined(__mips__) && defined(_ABI64)
+#  define __NR_bpf 5315
+# else
+#  error __NR_bpf not defined. libbpf does not support your arch.
+# endif
+#endif
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64) (unsigned long) ptr;
+}
+
+static inline int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr,
+			  unsigned int size)
+{
+	return syscall(__NR_bpf, cmd, attr, size);
+}
+
+static inline int sys_bpf_fd(enum bpf_cmd cmd, union bpf_attr *attr,
+			     unsigned int size)
+{
+	int fd;
+
+	fd = sys_bpf(cmd, attr, size);
+	return ensure_good_fd(fd);
+}
+
+int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)
+{
+	int fd;
+
+	do {
+		fd = sys_bpf_fd(BPF_PROG_LOAD, attr, size);
+	} while (fd < 0 && errno == EAGAIN && --attempts > 0);
+
+	return fd;
+}
+
+/* Probe whether kernel switched from memlock-based (RLIMIT_MEMLOCK) to
+ * memcg-based memory accounting for BPF maps and progs. This was done in [0].
+ * We use the support for bpf_ktime_get_coarse_ns() helper, which was added in
+ * the same 5.11 Linux release ([1]), to detect memcg-based accounting for BPF.
+ *
+ *   [0] https://lore.kernel.org/bpf/20201201215900.3569844-1-guro@fb.com/
+ *   [1] d05512618056 ("bpf: Add bpf_ktime_get_coarse_ns helper")
+ */
+int probe_memcg_account(void)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, attach_btf_obj_fd);
+	struct bpf_insn insns[] = {
+		BPF_EMIT_CALL(BPF_FUNC_ktime_get_coarse_ns),
+		BPF_EXIT_INSN(),
+	};
+	size_t insn_cnt = ARRAY_SIZE(insns);
+	union bpf_attr attr;
+	int prog_fd;
+
+	/* attempt loading freplace trying to use custom BTF */
+	memset(&attr, 0, attr_sz);
+	attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	attr.insns = ptr_to_u64(insns);
+	attr.insn_cnt = insn_cnt;
+	attr.license = ptr_to_u64("GPL");
+
+	prog_fd = sys_bpf_fd(BPF_PROG_LOAD, &attr, attr_sz);
+	if (prog_fd >= 0) {
+		close(prog_fd);
+		return 1;
+	}
+	return 0;
+}
+
+static bool memlock_bumped;
+static rlim_t memlock_rlim = RLIM_INFINITY;
+
+int libbpf_set_memlock_rlim(size_t memlock_bytes)
+{
+	if (memlock_bumped)
+		return libbpf_err(-EBUSY);
+
+	memlock_rlim = memlock_bytes;
+	return 0;
+}
+
+int bump_rlimit_memlock(void)
+{
+	struct rlimit rlim;
+
+	/* if kernel supports memcg-based accounting, skip bumping RLIMIT_MEMLOCK */
+	if (memlock_bumped || kernel_supports(NULL, FEAT_MEMCG_ACCOUNT))
+		return 0;
+
+	memlock_bumped = true;
+
+	/* zero memlock_rlim_max disables auto-bumping RLIMIT_MEMLOCK */
+	if (memlock_rlim == 0)
+		return 0;
+
+	rlim.rlim_cur = rlim.rlim_max = memlock_rlim;
+	if (setrlimit(RLIMIT_MEMLOCK, &rlim))
+		return -errno;
+
+	return 0;
+}
+
+int bpf_map_create(enum bpf_map_type map_type,
+		   const char *map_name,
+		   __u32 key_size,
+		   __u32 value_size,
+		   __u32 max_entries,
+		   const struct bpf_map_create_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, map_extra);
+	union bpf_attr attr;
+	int fd;
+
+	bump_rlimit_memlock();
+
+	memset(&attr, 0, attr_sz);
+
+	if (!OPTS_VALID(opts, bpf_map_create_opts))
+		return libbpf_err(-EINVAL);
+
+	attr.map_type = map_type;
+	if (map_name && kernel_supports(NULL, FEAT_PROG_NAME))
+		libbpf_strlcpy(attr.map_name, map_name, sizeof(attr.map_name));
+	attr.key_size = key_size;
+	attr.value_size = value_size;
+	attr.max_entries = max_entries;
+
+	attr.btf_fd = OPTS_GET(opts, btf_fd, 0);
+	attr.btf_key_type_id = OPTS_GET(opts, btf_key_type_id, 0);
+	attr.btf_value_type_id = OPTS_GET(opts, btf_value_type_id, 0);
+	attr.btf_vmlinux_value_type_id = OPTS_GET(opts, btf_vmlinux_value_type_id, 0);
+
+	attr.inner_map_fd = OPTS_GET(opts, inner_map_fd, 0);
+	attr.map_flags = OPTS_GET(opts, map_flags, 0);
+	attr.map_extra = OPTS_GET(opts, map_extra, 0);
+	attr.numa_node = OPTS_GET(opts, numa_node, 0);
+	attr.map_ifindex = OPTS_GET(opts, map_ifindex, 0);
+
+	fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, attr_sz);
+	return libbpf_err_errno(fd);
+}
+
+static void *
+alloc_zero_tailing_info(const void *orecord, __u32 cnt,
+			__u32 actual_rec_size, __u32 expected_rec_size)
+{
+	__u64 info_len = (__u64)actual_rec_size * cnt;
+	void *info, *nrecord;
+	int i;
+
+	info = malloc(info_len);
+	if (!info)
+		return NULL;
+
+	/* zero out bytes kernel does not understand */
+	nrecord = info;
+	for (i = 0; i < cnt; i++) {
+		memcpy(nrecord, orecord, expected_rec_size);
+		memset(nrecord + expected_rec_size, 0,
+		       actual_rec_size - expected_rec_size);
+		orecord += actual_rec_size;
+		nrecord += actual_rec_size;
+	}
+
+	return info;
+}
+
+int bpf_prog_load(enum bpf_prog_type prog_type,
+		  const char *prog_name, const char *license,
+		  const struct bpf_insn *insns, size_t insn_cnt,
+		  const struct bpf_prog_load_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, fd_array);
+	void *finfo = NULL, *linfo = NULL;
+	const char *func_info, *line_info;
+	__u32 log_size, log_level, attach_prog_fd, attach_btf_obj_fd;
+	__u32 func_info_rec_size, line_info_rec_size;
+	int fd, attempts;
+	union bpf_attr attr;
+	char *log_buf;
+
+	bump_rlimit_memlock();
+
+	if (!OPTS_VALID(opts, bpf_prog_load_opts))
+		return libbpf_err(-EINVAL);
+
+	attempts = OPTS_GET(opts, attempts, 0);
+	if (attempts < 0)
+		return libbpf_err(-EINVAL);
+	if (attempts == 0)
+		attempts = PROG_LOAD_ATTEMPTS;
+
+	memset(&attr, 0, attr_sz);
+
+	attr.prog_type = prog_type;
+	attr.expected_attach_type = OPTS_GET(opts, expected_attach_type, 0);
+
+	attr.prog_btf_fd = OPTS_GET(opts, prog_btf_fd, 0);
+	attr.prog_flags = OPTS_GET(opts, prog_flags, 0);
+	attr.prog_ifindex = OPTS_GET(opts, prog_ifindex, 0);
+	attr.kern_version = OPTS_GET(opts, kern_version, 0);
+
+	if (prog_name && kernel_supports(NULL, FEAT_PROG_NAME))
+		libbpf_strlcpy(attr.prog_name, prog_name, sizeof(attr.prog_name));
+	attr.license = ptr_to_u64(license);
+
+	if (insn_cnt > UINT_MAX)
+		return libbpf_err(-E2BIG);
+
+	attr.insns = ptr_to_u64(insns);
+	attr.insn_cnt = (__u32)insn_cnt;
+
+	attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0);
+	attach_btf_obj_fd = OPTS_GET(opts, attach_btf_obj_fd, 0);
+
+	if (attach_prog_fd && attach_btf_obj_fd)
+		return libbpf_err(-EINVAL);
+
+	attr.attach_btf_id = OPTS_GET(opts, attach_btf_id, 0);
+	if (attach_prog_fd)
+		attr.attach_prog_fd = attach_prog_fd;
+	else
+		attr.attach_btf_obj_fd = attach_btf_obj_fd;
+
+	log_buf = OPTS_GET(opts, log_buf, NULL);
+	log_size = OPTS_GET(opts, log_size, 0);
+	log_level = OPTS_GET(opts, log_level, 0);
+
+	if (!!log_buf != !!log_size)
+		return libbpf_err(-EINVAL);
+	if (log_level > (4 | 2 | 1))
+		return libbpf_err(-EINVAL);
+	if (log_level && !log_buf)
+		return libbpf_err(-EINVAL);
+
+	func_info_rec_size = OPTS_GET(opts, func_info_rec_size, 0);
+	func_info = OPTS_GET(opts, func_info, NULL);
+	attr.func_info_rec_size = func_info_rec_size;
+	attr.func_info = ptr_to_u64(func_info);
+	attr.func_info_cnt = OPTS_GET(opts, func_info_cnt, 0);
+
+	line_info_rec_size = OPTS_GET(opts, line_info_rec_size, 0);
+	line_info = OPTS_GET(opts, line_info, NULL);
+	attr.line_info_rec_size = line_info_rec_size;
+	attr.line_info = ptr_to_u64(line_info);
+	attr.line_info_cnt = OPTS_GET(opts, line_info_cnt, 0);
+
+	attr.fd_array = ptr_to_u64(OPTS_GET(opts, fd_array, NULL));
+
+	if (log_level) {
+		attr.log_buf = ptr_to_u64(log_buf);
+		attr.log_size = log_size;
+		attr.log_level = log_level;
+	}
+
+	fd = sys_bpf_prog_load(&attr, attr_sz, attempts);
+	if (fd >= 0)
+		return fd;
+
+	/* After bpf_prog_load, the kernel may modify certain attributes
+	 * to give user space a hint how to deal with loading failure.
+	 * Check to see whether we can make some changes and load again.
+	 */
+	while (errno == E2BIG && (!finfo || !linfo)) {
+		if (!finfo && attr.func_info_cnt &&
+		    attr.func_info_rec_size < func_info_rec_size) {
+			/* try with corrected func info records */
+			finfo = alloc_zero_tailing_info(func_info,
+							attr.func_info_cnt,
+							func_info_rec_size,
+							attr.func_info_rec_size);
+			if (!finfo) {
+				errno = E2BIG;
+				goto done;
+			}
+
+			attr.func_info = ptr_to_u64(finfo);
+			attr.func_info_rec_size = func_info_rec_size;
+		} else if (!linfo && attr.line_info_cnt &&
+			   attr.line_info_rec_size < line_info_rec_size) {
+			linfo = alloc_zero_tailing_info(line_info,
+							attr.line_info_cnt,
+							line_info_rec_size,
+							attr.line_info_rec_size);
+			if (!linfo) {
+				errno = E2BIG;
+				goto done;
+			}
+
+			attr.line_info = ptr_to_u64(linfo);
+			attr.line_info_rec_size = line_info_rec_size;
+		} else {
+			break;
+		}
+
+		fd = sys_bpf_prog_load(&attr, attr_sz, attempts);
+		if (fd >= 0)
+			goto done;
+	}
+
+	if (log_level == 0 && log_buf) {
+		/* log_level == 0 with non-NULL log_buf requires retrying on error
+		 * with log_level == 1 and log_buf/log_buf_size set, to get details of
+		 * failure
+		 */
+		attr.log_buf = ptr_to_u64(log_buf);
+		attr.log_size = log_size;
+		attr.log_level = 1;
+
+		fd = sys_bpf_prog_load(&attr, attr_sz, attempts);
+	}
+done:
+	/* free() doesn't affect errno, so we don't need to restore it */
+	free(finfo);
+	free(linfo);
+	return libbpf_err_errno(fd);
+}
+
+int bpf_map_update_elem(int fd, const void *key, const void *value,
+			__u64 flags)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.value = ptr_to_u64(value);
+	attr.flags = flags;
+
+	ret = sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_map_lookup_elem(int fd, const void *key, void *value)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.value = ptr_to_u64(value);
+
+	ret = sys_bpf(BPF_MAP_LOOKUP_ELEM, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_map_lookup_elem_flags(int fd, const void *key, void *value, __u64 flags)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.value = ptr_to_u64(value);
+	attr.flags = flags;
+
+	ret = sys_bpf(BPF_MAP_LOOKUP_ELEM, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_map_lookup_and_delete_elem(int fd, const void *key, void *value)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.value = ptr_to_u64(value);
+
+	ret = sys_bpf(BPF_MAP_LOOKUP_AND_DELETE_ELEM, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_map_lookup_and_delete_elem_flags(int fd, const void *key, void *value, __u64 flags)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.value = ptr_to_u64(value);
+	attr.flags = flags;
+
+	ret = sys_bpf(BPF_MAP_LOOKUP_AND_DELETE_ELEM, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_map_delete_elem(int fd, const void *key)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+
+	ret = sys_bpf(BPF_MAP_DELETE_ELEM, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_map_delete_elem_flags(int fd, const void *key, __u64 flags)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.flags = flags;
+
+	ret = sys_bpf(BPF_MAP_DELETE_ELEM, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_map_get_next_key(int fd, const void *key, void *next_key)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, next_key);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.next_key = ptr_to_u64(next_key);
+
+	ret = sys_bpf(BPF_MAP_GET_NEXT_KEY, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_map_freeze(int fd)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, map_fd);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_fd = fd;
+
+	ret = sys_bpf(BPF_MAP_FREEZE, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+static int bpf_map_batch_common(int cmd, int fd, void  *in_batch,
+				void *out_batch, void *keys, void *values,
+				__u32 *count,
+				const struct bpf_map_batch_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, batch);
+	union bpf_attr attr;
+	int ret;
+
+	if (!OPTS_VALID(opts, bpf_map_batch_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.batch.map_fd = fd;
+	attr.batch.in_batch = ptr_to_u64(in_batch);
+	attr.batch.out_batch = ptr_to_u64(out_batch);
+	attr.batch.keys = ptr_to_u64(keys);
+	attr.batch.values = ptr_to_u64(values);
+	attr.batch.count = *count;
+	attr.batch.elem_flags  = OPTS_GET(opts, elem_flags, 0);
+	attr.batch.flags = OPTS_GET(opts, flags, 0);
+
+	ret = sys_bpf(cmd, &attr, attr_sz);
+	*count = attr.batch.count;
+
+	return libbpf_err_errno(ret);
+}
+
+int bpf_map_delete_batch(int fd, const void *keys, __u32 *count,
+			 const struct bpf_map_batch_opts *opts)
+{
+	return bpf_map_batch_common(BPF_MAP_DELETE_BATCH, fd, NULL,
+				    NULL, (void *)keys, NULL, count, opts);
+}
+
+int bpf_map_lookup_batch(int fd, void *in_batch, void *out_batch, void *keys,
+			 void *values, __u32 *count,
+			 const struct bpf_map_batch_opts *opts)
+{
+	return bpf_map_batch_common(BPF_MAP_LOOKUP_BATCH, fd, in_batch,
+				    out_batch, keys, values, count, opts);
+}
+
+int bpf_map_lookup_and_delete_batch(int fd, void *in_batch, void *out_batch,
+				    void *keys, void *values, __u32 *count,
+				    const struct bpf_map_batch_opts *opts)
+{
+	return bpf_map_batch_common(BPF_MAP_LOOKUP_AND_DELETE_BATCH,
+				    fd, in_batch, out_batch, keys, values,
+				    count, opts);
+}
+
+int bpf_map_update_batch(int fd, const void *keys, const void *values, __u32 *count,
+			 const struct bpf_map_batch_opts *opts)
+{
+	return bpf_map_batch_common(BPF_MAP_UPDATE_BATCH, fd, NULL, NULL,
+				    (void *)keys, (void *)values, count, opts);
+}
+
+int bpf_obj_pin(int fd, const char *pathname)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, file_flags);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.pathname = ptr_to_u64((void *)pathname);
+	attr.bpf_fd = fd;
+
+	ret = sys_bpf(BPF_OBJ_PIN, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_obj_get(const char *pathname)
+{
+	return bpf_obj_get_opts(pathname, NULL);
+}
+
+int bpf_obj_get_opts(const char *pathname, const struct bpf_obj_get_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, file_flags);
+	union bpf_attr attr;
+	int fd;
+
+	if (!OPTS_VALID(opts, bpf_obj_get_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.pathname = ptr_to_u64((void *)pathname);
+	attr.file_flags = OPTS_GET(opts, file_flags, 0);
+
+	fd = sys_bpf_fd(BPF_OBJ_GET, &attr, attr_sz);
+	return libbpf_err_errno(fd);
+}
+
+int bpf_prog_attach(int prog_fd, int target_fd, enum bpf_attach_type type,
+		    unsigned int flags)
+{
+	DECLARE_LIBBPF_OPTS(bpf_prog_attach_opts, opts,
+		.flags = flags,
+	);
+
+	return bpf_prog_attach_opts(prog_fd, target_fd, type, &opts);
+}
+
+int bpf_prog_attach_opts(int prog_fd, int target_fd,
+			  enum bpf_attach_type type,
+			  const struct bpf_prog_attach_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, replace_bpf_fd);
+	union bpf_attr attr;
+	int ret;
+
+	if (!OPTS_VALID(opts, bpf_prog_attach_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.target_fd	   = target_fd;
+	attr.attach_bpf_fd = prog_fd;
+	attr.attach_type   = type;
+	attr.attach_flags  = OPTS_GET(opts, flags, 0);
+	attr.replace_bpf_fd = OPTS_GET(opts, replace_prog_fd, 0);
+
+	ret = sys_bpf(BPF_PROG_ATTACH, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_prog_detach(int target_fd, enum bpf_attach_type type)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, replace_bpf_fd);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.target_fd	 = target_fd;
+	attr.attach_type = type;
+
+	ret = sys_bpf(BPF_PROG_DETACH, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_prog_detach2(int prog_fd, int target_fd, enum bpf_attach_type type)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, replace_bpf_fd);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.target_fd	 = target_fd;
+	attr.attach_bpf_fd = prog_fd;
+	attr.attach_type = type;
+
+	ret = sys_bpf(BPF_PROG_DETACH, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_link_create(int prog_fd, int target_fd,
+		    enum bpf_attach_type attach_type,
+		    const struct bpf_link_create_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, link_create);
+	__u32 target_btf_id, iter_info_len;
+	union bpf_attr attr;
+	int fd, err;
+
+	if (!OPTS_VALID(opts, bpf_link_create_opts))
+		return libbpf_err(-EINVAL);
+
+	iter_info_len = OPTS_GET(opts, iter_info_len, 0);
+	target_btf_id = OPTS_GET(opts, target_btf_id, 0);
+
+	/* validate we don't have unexpected combinations of non-zero fields */
+	if (iter_info_len || target_btf_id) {
+		if (iter_info_len && target_btf_id)
+			return libbpf_err(-EINVAL);
+		if (!OPTS_ZEROED(opts, target_btf_id))
+			return libbpf_err(-EINVAL);
+	}
+
+	memset(&attr, 0, attr_sz);
+	attr.link_create.prog_fd = prog_fd;
+	attr.link_create.target_fd = target_fd;
+	attr.link_create.attach_type = attach_type;
+	attr.link_create.flags = OPTS_GET(opts, flags, 0);
+
+	if (target_btf_id) {
+		attr.link_create.target_btf_id = target_btf_id;
+		goto proceed;
+	}
+
+	switch (attach_type) {
+	case BPF_TRACE_ITER:
+		attr.link_create.iter_info = ptr_to_u64(OPTS_GET(opts, iter_info, (void *)0));
+		attr.link_create.iter_info_len = iter_info_len;
+		break;
+	case BPF_PERF_EVENT:
+		attr.link_create.perf_event.bpf_cookie = OPTS_GET(opts, perf_event.bpf_cookie, 0);
+		if (!OPTS_ZEROED(opts, perf_event))
+			return libbpf_err(-EINVAL);
+		break;
+	case BPF_TRACE_KPROBE_MULTI:
+		attr.link_create.kprobe_multi.flags = OPTS_GET(opts, kprobe_multi.flags, 0);
+		attr.link_create.kprobe_multi.cnt = OPTS_GET(opts, kprobe_multi.cnt, 0);
+		attr.link_create.kprobe_multi.syms = ptr_to_u64(OPTS_GET(opts, kprobe_multi.syms, 0));
+		attr.link_create.kprobe_multi.addrs = ptr_to_u64(OPTS_GET(opts, kprobe_multi.addrs, 0));
+		attr.link_create.kprobe_multi.cookies = ptr_to_u64(OPTS_GET(opts, kprobe_multi.cookies, 0));
+		if (!OPTS_ZEROED(opts, kprobe_multi))
+			return libbpf_err(-EINVAL);
+		break;
+	case BPF_TRACE_FENTRY:
+	case BPF_TRACE_FEXIT:
+	case BPF_MODIFY_RETURN:
+	case BPF_LSM_MAC:
+		attr.link_create.tracing.cookie = OPTS_GET(opts, tracing.cookie, 0);
+		if (!OPTS_ZEROED(opts, tracing))
+			return libbpf_err(-EINVAL);
+		break;
+	default:
+		if (!OPTS_ZEROED(opts, flags))
+			return libbpf_err(-EINVAL);
+		break;
+	}
+proceed:
+	fd = sys_bpf_fd(BPF_LINK_CREATE, &attr, attr_sz);
+	if (fd >= 0)
+		return fd;
+	/* we'll get EINVAL if LINK_CREATE doesn't support attaching fentry
+	 * and other similar programs
+	 */
+	err = -errno;
+	if (err != -EINVAL)
+		return libbpf_err(err);
+
+	/* if user used features not supported by
+	 * BPF_RAW_TRACEPOINT_OPEN command, then just give up immediately
+	 */
+	if (attr.link_create.target_fd || attr.link_create.target_btf_id)
+		return libbpf_err(err);
+	if (!OPTS_ZEROED(opts, sz))
+		return libbpf_err(err);
+
+	/* otherwise, for few select kinds of programs that can be
+	 * attached using BPF_RAW_TRACEPOINT_OPEN command, try that as
+	 * a fallback for older kernels
+	 */
+	switch (attach_type) {
+	case BPF_TRACE_RAW_TP:
+	case BPF_LSM_MAC:
+	case BPF_TRACE_FENTRY:
+	case BPF_TRACE_FEXIT:
+	case BPF_MODIFY_RETURN:
+		return bpf_raw_tracepoint_open(NULL, prog_fd);
+	default:
+		return libbpf_err(err);
+	}
+}
+
+int bpf_link_detach(int link_fd)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, link_detach);
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.link_detach.link_fd = link_fd;
+
+	ret = sys_bpf(BPF_LINK_DETACH, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_link_update(int link_fd, int new_prog_fd,
+		    const struct bpf_link_update_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, link_update);
+	union bpf_attr attr;
+	int ret;
+
+	if (!OPTS_VALID(opts, bpf_link_update_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.link_update.link_fd = link_fd;
+	attr.link_update.new_prog_fd = new_prog_fd;
+	attr.link_update.flags = OPTS_GET(opts, flags, 0);
+	attr.link_update.old_prog_fd = OPTS_GET(opts, old_prog_fd, 0);
+
+	ret = sys_bpf(BPF_LINK_UPDATE, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
+
+int bpf_iter_create(int link_fd)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, iter_create);
+	union bpf_attr attr;
+	int fd;
+
+	memset(&attr, 0, attr_sz);
+	attr.iter_create.link_fd = link_fd;
+
+	fd = sys_bpf_fd(BPF_ITER_CREATE, &attr, attr_sz);
+	return libbpf_err_errno(fd);
+}
+
+int bpf_prog_query_opts(int target_fd,
+			enum bpf_attach_type type,
+			struct bpf_prog_query_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, query);
+	union bpf_attr attr;
+	int ret;
+
+	if (!OPTS_VALID(opts, bpf_prog_query_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+
+	attr.query.target_fd	= target_fd;
+	attr.query.attach_type	= type;
+	attr.query.query_flags	= OPTS_GET(opts, query_flags, 0);
+	attr.query.prog_cnt	= OPTS_GET(opts, prog_cnt, 0);
+	attr.query.prog_ids	= ptr_to_u64(OPTS_GET(opts, prog_ids, NULL));
+	attr.query.prog_attach_flags = ptr_to_u64(OPTS_GET(opts, prog_attach_flags, NULL));
+
+	ret = sys_bpf(BPF_PROG_QUERY, &attr, attr_sz);
+
+	OPTS_SET(opts, attach_flags, attr.query.attach_flags);
+	OPTS_SET(opts, prog_cnt, attr.query.prog_cnt);
+
+	return libbpf_err_errno(ret);
+}
+
+int bpf_prog_query(int target_fd, enum bpf_attach_type type, __u32 query_flags,
+		   __u32 *attach_flags, __u32 *prog_ids, __u32 *prog_cnt)
+{
+	LIBBPF_OPTS(bpf_prog_query_opts, opts);
+	int ret;
+
+	opts.query_flags = query_flags;
+	opts.prog_ids = prog_ids;
+	opts.prog_cnt = *prog_cnt;
+
+	ret = bpf_prog_query_opts(target_fd, type, &opts);
+
+	if (attach_flags)
+		*attach_flags = opts.attach_flags;
+	*prog_cnt = opts.prog_cnt;
+
+	return libbpf_err_errno(ret);
+}
+
+int bpf_prog_test_run_opts(int prog_fd, struct bpf_test_run_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, test);
+	union bpf_attr attr;
+	int ret;
+
+	if (!OPTS_VALID(opts, bpf_test_run_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.test.prog_fd = prog_fd;
+	attr.test.batch_size = OPTS_GET(opts, batch_size, 0);
+	attr.test.cpu = OPTS_GET(opts, cpu, 0);
+	attr.test.flags = OPTS_GET(opts, flags, 0);
+	attr.test.repeat = OPTS_GET(opts, repeat, 0);
+	attr.test.duration = OPTS_GET(opts, duration, 0);
+	attr.test.ctx_size_in = OPTS_GET(opts, ctx_size_in, 0);
+	attr.test.ctx_size_out = OPTS_GET(opts, ctx_size_out, 0);
+	attr.test.data_size_in = OPTS_GET(opts, data_size_in, 0);
+	attr.test.data_size_out = OPTS_GET(opts, data_size_out, 0);
+	attr.test.ctx_in = ptr_to_u64(OPTS_GET(opts, ctx_in, NULL));
+	attr.test.ctx_out = ptr_to_u64(OPTS_GET(opts, ctx_out, NULL));
+	attr.test.data_in = ptr_to_u64(OPTS_GET(opts, data_in, NULL));
+	attr.test.data_out = ptr_to_u64(OPTS_GET(opts, data_out, NULL));
+
+	ret = sys_bpf(BPF_PROG_TEST_RUN, &attr, attr_sz);
+
+	OPTS_SET(opts, data_size_out, attr.test.data_size_out);
+	OPTS_SET(opts, ctx_size_out, attr.test.ctx_size_out);
+	OPTS_SET(opts, duration, attr.test.duration);
+	OPTS_SET(opts, retval, attr.test.retval);
+
+	return libbpf_err_errno(ret);
+}
+
+static int bpf_obj_get_next_id(__u32 start_id, __u32 *next_id, int cmd)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
+	union bpf_attr attr;
+	int err;
+
+	memset(&attr, 0, attr_sz);
+	attr.start_id = start_id;
+
+	err = sys_bpf(cmd, &attr, attr_sz);
+	if (!err)
+		*next_id = attr.next_id;
+
+	return libbpf_err_errno(err);
+}
+
+int bpf_prog_get_next_id(__u32 start_id, __u32 *next_id)
+{
+	return bpf_obj_get_next_id(start_id, next_id, BPF_PROG_GET_NEXT_ID);
+}
+
+int bpf_map_get_next_id(__u32 start_id, __u32 *next_id)
+{
+	return bpf_obj_get_next_id(start_id, next_id, BPF_MAP_GET_NEXT_ID);
+}
+
+int bpf_btf_get_next_id(__u32 start_id, __u32 *next_id)
+{
+	return bpf_obj_get_next_id(start_id, next_id, BPF_BTF_GET_NEXT_ID);
+}
+
+int bpf_link_get_next_id(__u32 start_id, __u32 *next_id)
+{
+	return bpf_obj_get_next_id(start_id, next_id, BPF_LINK_GET_NEXT_ID);
+}
+
+int bpf_prog_get_fd_by_id_opts(__u32 id,
+			       const struct bpf_get_fd_by_id_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
+	union bpf_attr attr;
+	int fd;
+
+	if (!OPTS_VALID(opts, bpf_get_fd_by_id_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.prog_id = id;
+	attr.open_flags = OPTS_GET(opts, open_flags, 0);
+
+	fd = sys_bpf_fd(BPF_PROG_GET_FD_BY_ID, &attr, attr_sz);
+	return libbpf_err_errno(fd);
+}
+
+int bpf_prog_get_fd_by_id(__u32 id)
+{
+	return bpf_prog_get_fd_by_id_opts(id, NULL);
+}
+
+int bpf_map_get_fd_by_id_opts(__u32 id,
+			      const struct bpf_get_fd_by_id_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
+	union bpf_attr attr;
+	int fd;
+
+	if (!OPTS_VALID(opts, bpf_get_fd_by_id_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.map_id = id;
+	attr.open_flags = OPTS_GET(opts, open_flags, 0);
+
+	fd = sys_bpf_fd(BPF_MAP_GET_FD_BY_ID, &attr, attr_sz);
+	return libbpf_err_errno(fd);
+}
+
+int bpf_map_get_fd_by_id(__u32 id)
+{
+	return bpf_map_get_fd_by_id_opts(id, NULL);
+}
+
+int bpf_btf_get_fd_by_id_opts(__u32 id,
+			      const struct bpf_get_fd_by_id_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
+	union bpf_attr attr;
+	int fd;
+
+	if (!OPTS_VALID(opts, bpf_get_fd_by_id_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.btf_id = id;
+	attr.open_flags = OPTS_GET(opts, open_flags, 0);
+
+	fd = sys_bpf_fd(BPF_BTF_GET_FD_BY_ID, &attr, attr_sz);
+	return libbpf_err_errno(fd);
+}
+
+int bpf_btf_get_fd_by_id(__u32 id)
+{
+	return bpf_btf_get_fd_by_id_opts(id, NULL);
+}
+
+int bpf_link_get_fd_by_id_opts(__u32 id,
+			       const struct bpf_get_fd_by_id_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
+	union bpf_attr attr;
+	int fd;
+
+	if (!OPTS_VALID(opts, bpf_get_fd_by_id_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.link_id = id;
+	attr.open_flags = OPTS_GET(opts, open_flags, 0);
+
+	fd = sys_bpf_fd(BPF_LINK_GET_FD_BY_ID, &attr, attr_sz);
+	return libbpf_err_errno(fd);
+}
+
+int bpf_link_get_fd_by_id(__u32 id)
+{
+	return bpf_link_get_fd_by_id_opts(id, NULL);
+}
+
+int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, info);
+	union bpf_attr attr;
+	int err;
+
+	memset(&attr, 0, attr_sz);
+	attr.info.bpf_fd = bpf_fd;
+	attr.info.info_len = *info_len;
+	attr.info.info = ptr_to_u64(info);
+
+	err = sys_bpf(BPF_OBJ_GET_INFO_BY_FD, &attr, attr_sz);
+	if (!err)
+		*info_len = attr.info.info_len;
+	return libbpf_err_errno(err);
+}
+
+int bpf_raw_tracepoint_open(const char *name, int prog_fd)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, raw_tracepoint);
+	union bpf_attr attr;
+	int fd;
+
+	memset(&attr, 0, attr_sz);
+	attr.raw_tracepoint.name = ptr_to_u64(name);
+	attr.raw_tracepoint.prog_fd = prog_fd;
+
+	fd = sys_bpf_fd(BPF_RAW_TRACEPOINT_OPEN, &attr, attr_sz);
+	return libbpf_err_errno(fd);
+}
+
+int bpf_btf_load(const void *btf_data, size_t btf_size, const struct bpf_btf_load_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, btf_log_level);
+	union bpf_attr attr;
+	char *log_buf;
+	size_t log_size;
+	__u32 log_level;
+	int fd;
+
+	bump_rlimit_memlock();
+
+	memset(&attr, 0, attr_sz);
+
+	if (!OPTS_VALID(opts, bpf_btf_load_opts))
+		return libbpf_err(-EINVAL);
+
+	log_buf = OPTS_GET(opts, log_buf, NULL);
+	log_size = OPTS_GET(opts, log_size, 0);
+	log_level = OPTS_GET(opts, log_level, 0);
+
+	if (log_size > UINT_MAX)
+		return libbpf_err(-EINVAL);
+	if (log_size && !log_buf)
+		return libbpf_err(-EINVAL);
+
+	attr.btf = ptr_to_u64(btf_data);
+	attr.btf_size = btf_size;
+	/* log_level == 0 and log_buf != NULL means "try loading without
+	 * log_buf, but retry with log_buf and log_level=1 on error", which is
+	 * consistent across low-level and high-level BTF and program loading
+	 * APIs within libbpf and provides a sensible behavior in practice
+	 */
+	if (log_level) {
+		attr.btf_log_buf = ptr_to_u64(log_buf);
+		attr.btf_log_size = (__u32)log_size;
+		attr.btf_log_level = log_level;
+	}
+
+	fd = sys_bpf_fd(BPF_BTF_LOAD, &attr, attr_sz);
+	if (fd < 0 && log_buf && log_level == 0) {
+		attr.btf_log_buf = ptr_to_u64(log_buf);
+		attr.btf_log_size = (__u32)log_size;
+		attr.btf_log_level = 1;
+		fd = sys_bpf_fd(BPF_BTF_LOAD, &attr, attr_sz);
+	}
+	return libbpf_err_errno(fd);
+}
+
+int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf, __u32 *buf_len,
+		      __u32 *prog_id, __u32 *fd_type, __u64 *probe_offset,
+		      __u64 *probe_addr)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, task_fd_query);
+	union bpf_attr attr;
+	int err;
+
+	memset(&attr, 0, attr_sz);
+	attr.task_fd_query.pid = pid;
+	attr.task_fd_query.fd = fd;
+	attr.task_fd_query.flags = flags;
+	attr.task_fd_query.buf = ptr_to_u64(buf);
+	attr.task_fd_query.buf_len = *buf_len;
+
+	err = sys_bpf(BPF_TASK_FD_QUERY, &attr, attr_sz);
+
+	*buf_len = attr.task_fd_query.buf_len;
+	*prog_id = attr.task_fd_query.prog_id;
+	*fd_type = attr.task_fd_query.fd_type;
+	*probe_offset = attr.task_fd_query.probe_offset;
+	*probe_addr = attr.task_fd_query.probe_addr;
+
+	return libbpf_err_errno(err);
+}
+
+int bpf_enable_stats(enum bpf_stats_type type)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, enable_stats);
+	union bpf_attr attr;
+	int fd;
+
+	memset(&attr, 0, attr_sz);
+	attr.enable_stats.type = type;
+
+	fd = sys_bpf_fd(BPF_ENABLE_STATS, &attr, attr_sz);
+	return libbpf_err_errno(fd);
+}
+
+int bpf_prog_bind_map(int prog_fd, int map_fd,
+		      const struct bpf_prog_bind_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, prog_bind_map);
+	union bpf_attr attr;
+	int ret;
+
+	if (!OPTS_VALID(opts, bpf_prog_bind_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.prog_bind_map.prog_fd = prog_fd;
+	attr.prog_bind_map.map_fd = map_fd;
+	attr.prog_bind_map.flags = OPTS_GET(opts, flags, 0);
+
+	ret = sys_bpf(BPF_PROG_BIND_MAP, &attr, attr_sz);
+	return libbpf_err_errno(ret);
+}
diff --git a/src/bpf.h b/src/bpf.h
new file mode 100644
index 0000000..7468978
--- /dev/null
+++ b/src/bpf.h
@@ -0,0 +1,461 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * common eBPF ELF operations.
+ *
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License (not later!)
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not,  see <http://www.gnu.org/licenses>
+ */
+#ifndef __LIBBPF_BPF_H
+#define __LIBBPF_BPF_H
+
+#include <linux/bpf.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "libbpf_common.h"
+#include "libbpf_legacy.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int libbpf_set_memlock_rlim(size_t memlock_bytes);
+
+struct bpf_map_create_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+
+	__u32 btf_fd;
+	__u32 btf_key_type_id;
+	__u32 btf_value_type_id;
+	__u32 btf_vmlinux_value_type_id;
+
+	__u32 inner_map_fd;
+	__u32 map_flags;
+	__u64 map_extra;
+
+	__u32 numa_node;
+	__u32 map_ifindex;
+};
+#define bpf_map_create_opts__last_field map_ifindex
+
+LIBBPF_API int bpf_map_create(enum bpf_map_type map_type,
+			      const char *map_name,
+			      __u32 key_size,
+			      __u32 value_size,
+			      __u32 max_entries,
+			      const struct bpf_map_create_opts *opts);
+
+struct bpf_prog_load_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+
+	/* libbpf can retry BPF_PROG_LOAD command if bpf() syscall returns
+	 * -EAGAIN. This field determines how many attempts libbpf has to
+	 *  make. If not specified, libbpf will use default value of 5.
+	 */
+	int attempts;
+
+	enum bpf_attach_type expected_attach_type;
+	__u32 prog_btf_fd;
+	__u32 prog_flags;
+	__u32 prog_ifindex;
+	__u32 kern_version;
+
+	__u32 attach_btf_id;
+	__u32 attach_prog_fd;
+	__u32 attach_btf_obj_fd;
+
+	const int *fd_array;
+
+	/* .BTF.ext func info data */
+	const void *func_info;
+	__u32 func_info_cnt;
+	__u32 func_info_rec_size;
+
+	/* .BTF.ext line info data */
+	const void *line_info;
+	__u32 line_info_cnt;
+	__u32 line_info_rec_size;
+
+	/* verifier log options */
+	__u32 log_level;
+	__u32 log_size;
+	char *log_buf;
+};
+#define bpf_prog_load_opts__last_field log_buf
+
+LIBBPF_API int bpf_prog_load(enum bpf_prog_type prog_type,
+			     const char *prog_name, const char *license,
+			     const struct bpf_insn *insns, size_t insn_cnt,
+			     const struct bpf_prog_load_opts *opts);
+
+/* Flags to direct loading requirements */
+#define MAPS_RELAX_COMPAT	0x01
+
+/* Recommended log buffer size */
+#define BPF_LOG_BUF_SIZE (UINT32_MAX >> 8) /* verifier maximum in kernels <= 5.1 */
+
+struct bpf_btf_load_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+
+	/* kernel log options */
+	char *log_buf;
+	__u32 log_level;
+	__u32 log_size;
+};
+#define bpf_btf_load_opts__last_field log_size
+
+LIBBPF_API int bpf_btf_load(const void *btf_data, size_t btf_size,
+			    const struct bpf_btf_load_opts *opts);
+
+LIBBPF_API int bpf_map_update_elem(int fd, const void *key, const void *value,
+				   __u64 flags);
+
+LIBBPF_API int bpf_map_lookup_elem(int fd, const void *key, void *value);
+LIBBPF_API int bpf_map_lookup_elem_flags(int fd, const void *key, void *value,
+					 __u64 flags);
+LIBBPF_API int bpf_map_lookup_and_delete_elem(int fd, const void *key,
+					      void *value);
+LIBBPF_API int bpf_map_lookup_and_delete_elem_flags(int fd, const void *key,
+						    void *value, __u64 flags);
+LIBBPF_API int bpf_map_delete_elem(int fd, const void *key);
+LIBBPF_API int bpf_map_delete_elem_flags(int fd, const void *key, __u64 flags);
+LIBBPF_API int bpf_map_get_next_key(int fd, const void *key, void *next_key);
+LIBBPF_API int bpf_map_freeze(int fd);
+
+struct bpf_map_batch_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	__u64 elem_flags;
+	__u64 flags;
+};
+#define bpf_map_batch_opts__last_field flags
+
+
+/**
+ * @brief **bpf_map_delete_batch()** allows for batch deletion of multiple
+ * elements in a BPF map.
+ *
+ * @param fd BPF map file descriptor
+ * @param keys pointer to an array of *count* keys
+ * @param count input and output parameter; on input **count** represents the
+ * number of  elements in the map to delete in batch;
+ * on output if a non-EFAULT error is returned, **count** represents the number of deleted
+ * elements if the output **count** value is not equal to the input **count** value
+ * If EFAULT is returned, **count** should not be trusted to be correct.
+ * @param opts options for configuring the way the batch deletion works
+ * @return 0, on success; negative error code, otherwise (errno is also set to
+ * the error code)
+ */
+LIBBPF_API int bpf_map_delete_batch(int fd, const void *keys,
+				    __u32 *count,
+				    const struct bpf_map_batch_opts *opts);
+
+/**
+ * @brief **bpf_map_lookup_batch()** allows for batch lookup of BPF map elements.
+ *
+ * The parameter *in_batch* is the address of the first element in the batch to read.
+ * *out_batch* is an output parameter that should be passed as *in_batch* to subsequent
+ * calls to **bpf_map_lookup_batch()**. NULL can be passed for *in_batch* to indicate
+ * that the batched lookup starts from the beginning of the map.
+ *
+ * The *keys* and *values* are output parameters which must point to memory large enough to
+ * hold *count* items based on the key and value size of the map *map_fd*. The *keys*
+ * buffer must be of *key_size* * *count*. The *values* buffer must be of
+ * *value_size* * *count*.
+ *
+ * @param fd BPF map file descriptor
+ * @param in_batch address of the first element in batch to read, can pass NULL to
+ * indicate that the batched lookup starts from the beginning of the map.
+ * @param out_batch output parameter that should be passed to next call as *in_batch*
+ * @param keys pointer to an array large enough for *count* keys
+ * @param values pointer to an array large enough for *count* values
+ * @param count input and output parameter; on input it's the number of elements
+ * in the map to read in batch; on output it's the number of elements that were
+ * successfully read.
+ * If a non-EFAULT error is returned, count will be set as the number of elements
+ * that were read before the error occurred.
+ * If EFAULT is returned, **count** should not be trusted to be correct.
+ * @param opts options for configuring the way the batch lookup works
+ * @return 0, on success; negative error code, otherwise (errno is also set to
+ * the error code)
+ */
+LIBBPF_API int bpf_map_lookup_batch(int fd, void *in_batch, void *out_batch,
+				    void *keys, void *values, __u32 *count,
+				    const struct bpf_map_batch_opts *opts);
+
+/**
+ * @brief **bpf_map_lookup_and_delete_batch()** allows for batch lookup and deletion
+ * of BPF map elements where each element is deleted after being retrieved.
+ *
+ * @param fd BPF map file descriptor
+ * @param in_batch address of the first element in batch to read, can pass NULL to
+ * get address of the first element in *out_batch*
+ * @param out_batch output parameter that should be passed to next call as *in_batch*
+ * @param keys pointer to an array of *count* keys
+ * @param values pointer to an array large enough for *count* values
+ * @param count input and output parameter; on input it's the number of elements
+ * in the map to read and delete in batch; on output it represents the number of
+ * elements that were successfully read and deleted
+ * If a non-**EFAULT** error code is returned and if the output **count** value
+ * is not equal to the input **count** value, up to **count** elements may
+ * have been deleted.
+ * if **EFAULT** is returned up to *count* elements may have been deleted without
+ * being returned via the *keys* and *values* output parameters.
+ * @param opts options for configuring the way the batch lookup and delete works
+ * @return 0, on success; negative error code, otherwise (errno is also set to
+ * the error code)
+ */
+LIBBPF_API int bpf_map_lookup_and_delete_batch(int fd, void *in_batch,
+					void *out_batch, void *keys,
+					void *values, __u32 *count,
+					const struct bpf_map_batch_opts *opts);
+
+/**
+ * @brief **bpf_map_update_batch()** updates multiple elements in a map
+ * by specifying keys and their corresponding values.
+ *
+ * The *keys* and *values* parameters must point to memory large enough
+ * to hold *count* items based on the key and value size of the map.
+ *
+ * The *opts* parameter can be used to control how *bpf_map_update_batch()*
+ * should handle keys that either do or do not already exist in the map.
+ * In particular the *flags* parameter of *bpf_map_batch_opts* can be
+ * one of the following:
+ *
+ * Note that *count* is an input and output parameter, where on output it
+ * represents how many elements were successfully updated. Also note that if
+ * **EFAULT** then *count* should not be trusted to be correct.
+ *
+ * **BPF_ANY**
+ *    Create new elements or update existing.
+ *
+ * **BPF_NOEXIST**
+ *    Create new elements only if they do not exist.
+ *
+ * **BPF_EXIST**
+ *    Update existing elements.
+ *
+ * **BPF_F_LOCK**
+ *    Update spin_lock-ed map elements. This must be
+ *    specified if the map value contains a spinlock.
+ *
+ * @param fd BPF map file descriptor
+ * @param keys pointer to an array of *count* keys
+ * @param values pointer to an array of *count* values
+ * @param count input and output parameter; on input it's the number of elements
+ * in the map to update in batch; on output if a non-EFAULT error is returned,
+ * **count** represents the number of updated elements if the output **count**
+ * value is not equal to the input **count** value.
+ * If EFAULT is returned, **count** should not be trusted to be correct.
+ * @param opts options for configuring the way the batch update works
+ * @return 0, on success; negative error code, otherwise (errno is also set to
+ * the error code)
+ */
+LIBBPF_API int bpf_map_update_batch(int fd, const void *keys, const void *values,
+				    __u32 *count,
+				    const struct bpf_map_batch_opts *opts);
+
+struct bpf_obj_get_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+
+	__u32 file_flags;
+
+	size_t :0;
+};
+#define bpf_obj_get_opts__last_field file_flags
+
+LIBBPF_API int bpf_obj_pin(int fd, const char *pathname);
+LIBBPF_API int bpf_obj_get(const char *pathname);
+LIBBPF_API int bpf_obj_get_opts(const char *pathname,
+				const struct bpf_obj_get_opts *opts);
+
+struct bpf_prog_attach_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	unsigned int flags;
+	int replace_prog_fd;
+};
+#define bpf_prog_attach_opts__last_field replace_prog_fd
+
+LIBBPF_API int bpf_prog_attach(int prog_fd, int attachable_fd,
+			       enum bpf_attach_type type, unsigned int flags);
+LIBBPF_API int bpf_prog_attach_opts(int prog_fd, int attachable_fd,
+				     enum bpf_attach_type type,
+				     const struct bpf_prog_attach_opts *opts);
+LIBBPF_API int bpf_prog_detach(int attachable_fd, enum bpf_attach_type type);
+LIBBPF_API int bpf_prog_detach2(int prog_fd, int attachable_fd,
+				enum bpf_attach_type type);
+
+union bpf_iter_link_info; /* defined in up-to-date linux/bpf.h */
+struct bpf_link_create_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	__u32 flags;
+	union bpf_iter_link_info *iter_info;
+	__u32 iter_info_len;
+	__u32 target_btf_id;
+	union {
+		struct {
+			__u64 bpf_cookie;
+		} perf_event;
+		struct {
+			__u32 flags;
+			__u32 cnt;
+			const char **syms;
+			const unsigned long *addrs;
+			const __u64 *cookies;
+		} kprobe_multi;
+		struct {
+			__u64 cookie;
+		} tracing;
+	};
+	size_t :0;
+};
+#define bpf_link_create_opts__last_field kprobe_multi.cookies
+
+LIBBPF_API int bpf_link_create(int prog_fd, int target_fd,
+			       enum bpf_attach_type attach_type,
+			       const struct bpf_link_create_opts *opts);
+
+LIBBPF_API int bpf_link_detach(int link_fd);
+
+struct bpf_link_update_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	__u32 flags;	   /* extra flags */
+	__u32 old_prog_fd; /* expected old program FD */
+};
+#define bpf_link_update_opts__last_field old_prog_fd
+
+LIBBPF_API int bpf_link_update(int link_fd, int new_prog_fd,
+			       const struct bpf_link_update_opts *opts);
+
+LIBBPF_API int bpf_iter_create(int link_fd);
+
+struct bpf_prog_test_run_attr {
+	int prog_fd;
+	int repeat;
+	const void *data_in;
+	__u32 data_size_in;
+	void *data_out;      /* optional */
+	__u32 data_size_out; /* in: max length of data_out
+			      * out: length of data_out */
+	__u32 retval;        /* out: return code of the BPF program */
+	__u32 duration;      /* out: average per repetition in ns */
+	const void *ctx_in; /* optional */
+	__u32 ctx_size_in;
+	void *ctx_out;      /* optional */
+	__u32 ctx_size_out; /* in: max length of ctx_out
+			     * out: length of cxt_out */
+};
+
+LIBBPF_API int bpf_prog_get_next_id(__u32 start_id, __u32 *next_id);
+LIBBPF_API int bpf_map_get_next_id(__u32 start_id, __u32 *next_id);
+LIBBPF_API int bpf_btf_get_next_id(__u32 start_id, __u32 *next_id);
+LIBBPF_API int bpf_link_get_next_id(__u32 start_id, __u32 *next_id);
+
+struct bpf_get_fd_by_id_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	__u32 open_flags; /* permissions requested for the operation on fd */
+	size_t :0;
+};
+#define bpf_get_fd_by_id_opts__last_field open_flags
+
+LIBBPF_API int bpf_prog_get_fd_by_id(__u32 id);
+LIBBPF_API int bpf_prog_get_fd_by_id_opts(__u32 id,
+				const struct bpf_get_fd_by_id_opts *opts);
+LIBBPF_API int bpf_map_get_fd_by_id(__u32 id);
+LIBBPF_API int bpf_map_get_fd_by_id_opts(__u32 id,
+				const struct bpf_get_fd_by_id_opts *opts);
+LIBBPF_API int bpf_btf_get_fd_by_id(__u32 id);
+LIBBPF_API int bpf_btf_get_fd_by_id_opts(__u32 id,
+				const struct bpf_get_fd_by_id_opts *opts);
+LIBBPF_API int bpf_link_get_fd_by_id(__u32 id);
+LIBBPF_API int bpf_link_get_fd_by_id_opts(__u32 id,
+				const struct bpf_get_fd_by_id_opts *opts);
+LIBBPF_API int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len);
+
+struct bpf_prog_query_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	__u32 query_flags;
+	__u32 attach_flags; /* output argument */
+	__u32 *prog_ids;
+	__u32 prog_cnt; /* input+output argument */
+	__u32 *prog_attach_flags;
+};
+#define bpf_prog_query_opts__last_field prog_attach_flags
+
+LIBBPF_API int bpf_prog_query_opts(int target_fd,
+				   enum bpf_attach_type type,
+				   struct bpf_prog_query_opts *opts);
+LIBBPF_API int bpf_prog_query(int target_fd, enum bpf_attach_type type,
+			      __u32 query_flags, __u32 *attach_flags,
+			      __u32 *prog_ids, __u32 *prog_cnt);
+
+LIBBPF_API int bpf_raw_tracepoint_open(const char *name, int prog_fd);
+LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
+				 __u32 *buf_len, __u32 *prog_id, __u32 *fd_type,
+				 __u64 *probe_offset, __u64 *probe_addr);
+
+#ifdef __cplusplus
+/* forward-declaring enums in C++ isn't compatible with pure C enums, so
+ * instead define bpf_enable_stats() as accepting int as an input
+ */
+LIBBPF_API int bpf_enable_stats(int type);
+#else
+enum bpf_stats_type; /* defined in up-to-date linux/bpf.h */
+LIBBPF_API int bpf_enable_stats(enum bpf_stats_type type);
+#endif
+
+struct bpf_prog_bind_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	__u32 flags;
+};
+#define bpf_prog_bind_opts__last_field flags
+
+LIBBPF_API int bpf_prog_bind_map(int prog_fd, int map_fd,
+				 const struct bpf_prog_bind_opts *opts);
+
+struct bpf_test_run_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	const void *data_in; /* optional */
+	void *data_out;      /* optional */
+	__u32 data_size_in;
+	__u32 data_size_out; /* in: max length of data_out
+			      * out: length of data_out
+			      */
+	const void *ctx_in; /* optional */
+	void *ctx_out;      /* optional */
+	__u32 ctx_size_in;
+	__u32 ctx_size_out; /* in: max length of ctx_out
+			     * out: length of cxt_out
+			     */
+	__u32 retval;        /* out: return code of the BPF program */
+	int repeat;
+	__u32 duration;      /* out: average per repetition in ns */
+	__u32 flags;
+	__u32 cpu;
+	__u32 batch_size;
+};
+#define bpf_test_run_opts__last_field batch_size
+
+LIBBPF_API int bpf_prog_test_run_opts(int prog_fd,
+				      struct bpf_test_run_opts *opts);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* __LIBBPF_BPF_H */
diff --git a/src/bpf_core_read.h b/src/bpf_core_read.h
new file mode 100644
index 0000000..496e6a8
--- /dev/null
+++ b/src/bpf_core_read.h
@@ -0,0 +1,484 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __BPF_CORE_READ_H__
+#define __BPF_CORE_READ_H__
+
+/*
+ * enum bpf_field_info_kind is passed as a second argument into
+ * __builtin_preserve_field_info() built-in to get a specific aspect of
+ * a field, captured as a first argument. __builtin_preserve_field_info(field,
+ * info_kind) returns __u32 integer and produces BTF field relocation, which
+ * is understood and processed by libbpf during BPF object loading. See
+ * selftests/bpf for examples.
+ */
+enum bpf_field_info_kind {
+	BPF_FIELD_BYTE_OFFSET = 0,	/* field byte offset */
+	BPF_FIELD_BYTE_SIZE = 1,
+	BPF_FIELD_EXISTS = 2,		/* field existence in target kernel */
+	BPF_FIELD_SIGNED = 3,
+	BPF_FIELD_LSHIFT_U64 = 4,
+	BPF_FIELD_RSHIFT_U64 = 5,
+};
+
+/* second argument to __builtin_btf_type_id() built-in */
+enum bpf_type_id_kind {
+	BPF_TYPE_ID_LOCAL = 0,		/* BTF type ID in local program */
+	BPF_TYPE_ID_TARGET = 1,		/* BTF type ID in target kernel */
+};
+
+/* second argument to __builtin_preserve_type_info() built-in */
+enum bpf_type_info_kind {
+	BPF_TYPE_EXISTS = 0,		/* type existence in target kernel */
+	BPF_TYPE_SIZE = 1,		/* type size in target kernel */
+	BPF_TYPE_MATCHES = 2,		/* type match in target kernel */
+};
+
+/* second argument to __builtin_preserve_enum_value() built-in */
+enum bpf_enum_value_kind {
+	BPF_ENUMVAL_EXISTS = 0,		/* enum value existence in kernel */
+	BPF_ENUMVAL_VALUE = 1,		/* enum value value relocation */
+};
+
+#define __CORE_RELO(src, field, info)					      \
+	__builtin_preserve_field_info((src)->field, BPF_FIELD_##info)
+
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define __CORE_BITFIELD_PROBE_READ(dst, src, fld)			      \
+	bpf_probe_read_kernel(						      \
+			(void *)dst,				      \
+			__CORE_RELO(src, fld, BYTE_SIZE),		      \
+			(const void *)src + __CORE_RELO(src, fld, BYTE_OFFSET))
+#else
+/* semantics of LSHIFT_64 assumes loading values into low-ordered bytes, so
+ * for big-endian we need to adjust destination pointer accordingly, based on
+ * field byte size
+ */
+#define __CORE_BITFIELD_PROBE_READ(dst, src, fld)			      \
+	bpf_probe_read_kernel(						      \
+			(void *)dst + (8 - __CORE_RELO(src, fld, BYTE_SIZE)), \
+			__CORE_RELO(src, fld, BYTE_SIZE),		      \
+			(const void *)src + __CORE_RELO(src, fld, BYTE_OFFSET))
+#endif
+
+/*
+ * Extract bitfield, identified by s->field, and return its value as u64.
+ * All this is done in relocatable manner, so bitfield changes such as
+ * signedness, bit size, offset changes, this will be handled automatically.
+ * This version of macro is using bpf_probe_read_kernel() to read underlying
+ * integer storage. Macro functions as an expression and its return type is
+ * bpf_probe_read_kernel()'s return value: 0, on success, <0 on error.
+ */
+#define BPF_CORE_READ_BITFIELD_PROBED(s, field) ({			      \
+	unsigned long long val = 0;					      \
+									      \
+	__CORE_BITFIELD_PROBE_READ(&val, s, field);			      \
+	val <<= __CORE_RELO(s, field, LSHIFT_U64);			      \
+	if (__CORE_RELO(s, field, SIGNED))				      \
+		val = ((long long)val) >> __CORE_RELO(s, field, RSHIFT_U64);  \
+	else								      \
+		val = val >> __CORE_RELO(s, field, RSHIFT_U64);		      \
+	val;								      \
+})
+
+/*
+ * Extract bitfield, identified by s->field, and return its value as u64.
+ * This version of macro is using direct memory reads and should be used from
+ * BPF program types that support such functionality (e.g., typed raw
+ * tracepoints).
+ */
+#define BPF_CORE_READ_BITFIELD(s, field) ({				      \
+	const void *p = (const void *)s + __CORE_RELO(s, field, BYTE_OFFSET); \
+	unsigned long long val;						      \
+									      \
+	/* This is a so-called barrier_var() operation that makes specified   \
+	 * variable "a black box" for optimizing compiler.		      \
+	 * It forces compiler to perform BYTE_OFFSET relocation on p and use  \
+	 * its calculated value in the switch below, instead of applying      \
+	 * the same relocation 4 times for each individual memory load.       \
+	 */								      \
+	asm volatile("" : "=r"(p) : "0"(p));				      \
+									      \
+	switch (__CORE_RELO(s, field, BYTE_SIZE)) {			      \
+	case 1: val = *(const unsigned char *)p; break;			      \
+	case 2: val = *(const unsigned short *)p; break;		      \
+	case 4: val = *(const unsigned int *)p; break;			      \
+	case 8: val = *(const unsigned long long *)p; break;		      \
+	}								      \
+	val <<= __CORE_RELO(s, field, LSHIFT_U64);			      \
+	if (__CORE_RELO(s, field, SIGNED))				      \
+		val = ((long long)val) >> __CORE_RELO(s, field, RSHIFT_U64);  \
+	else								      \
+		val = val >> __CORE_RELO(s, field, RSHIFT_U64);		      \
+	val;								      \
+})
+
+#define ___bpf_field_ref1(field)	(field)
+#define ___bpf_field_ref2(type, field)	(((typeof(type) *)0)->field)
+#define ___bpf_field_ref(args...)					    \
+	___bpf_apply(___bpf_field_ref, ___bpf_narg(args))(args)
+
+/*
+ * Convenience macro to check that field actually exists in target kernel's.
+ * Returns:
+ *    1, if matching field is present in target kernel;
+ *    0, if no matching field found.
+ *
+ * Supports two forms:
+ *   - field reference through variable access:
+ *     bpf_core_field_exists(p->my_field);
+ *   - field reference through type and field names:
+ *     bpf_core_field_exists(struct my_type, my_field).
+ */
+#define bpf_core_field_exists(field...)					    \
+	__builtin_preserve_field_info(___bpf_field_ref(field), BPF_FIELD_EXISTS)
+
+/*
+ * Convenience macro to get the byte size of a field. Works for integers,
+ * struct/unions, pointers, arrays, and enums.
+ *
+ * Supports two forms:
+ *   - field reference through variable access:
+ *     bpf_core_field_size(p->my_field);
+ *   - field reference through type and field names:
+ *     bpf_core_field_size(struct my_type, my_field).
+ */
+#define bpf_core_field_size(field...)					    \
+	__builtin_preserve_field_info(___bpf_field_ref(field), BPF_FIELD_BYTE_SIZE)
+
+/*
+ * Convenience macro to get field's byte offset.
+ *
+ * Supports two forms:
+ *   - field reference through variable access:
+ *     bpf_core_field_offset(p->my_field);
+ *   - field reference through type and field names:
+ *     bpf_core_field_offset(struct my_type, my_field).
+ */
+#define bpf_core_field_offset(field...)					    \
+	__builtin_preserve_field_info(___bpf_field_ref(field), BPF_FIELD_BYTE_OFFSET)
+
+/*
+ * Convenience macro to get BTF type ID of a specified type, using a local BTF
+ * information. Return 32-bit unsigned integer with type ID from program's own
+ * BTF. Always succeeds.
+ */
+#define bpf_core_type_id_local(type)					    \
+	__builtin_btf_type_id(*(typeof(type) *)0, BPF_TYPE_ID_LOCAL)
+
+/*
+ * Convenience macro to get BTF type ID of a target kernel's type that matches
+ * specified local type.
+ * Returns:
+ *    - valid 32-bit unsigned type ID in kernel BTF;
+ *    - 0, if no matching type was found in a target kernel BTF.
+ */
+#define bpf_core_type_id_kernel(type)					    \
+	__builtin_btf_type_id(*(typeof(type) *)0, BPF_TYPE_ID_TARGET)
+
+/*
+ * Convenience macro to check that provided named type
+ * (struct/union/enum/typedef) exists in a target kernel.
+ * Returns:
+ *    1, if such type is present in target kernel's BTF;
+ *    0, if no matching type is found.
+ */
+#define bpf_core_type_exists(type)					    \
+	__builtin_preserve_type_info(*(typeof(type) *)0, BPF_TYPE_EXISTS)
+
+/*
+ * Convenience macro to check that provided named type
+ * (struct/union/enum/typedef) "matches" that in a target kernel.
+ * Returns:
+ *    1, if the type matches in the target kernel's BTF;
+ *    0, if the type does not match any in the target kernel
+ */
+#define bpf_core_type_matches(type)					    \
+	__builtin_preserve_type_info(*(typeof(type) *)0, BPF_TYPE_MATCHES)
+
+/*
+ * Convenience macro to get the byte size of a provided named type
+ * (struct/union/enum/typedef) in a target kernel.
+ * Returns:
+ *    >= 0 size (in bytes), if type is present in target kernel's BTF;
+ *    0, if no matching type is found.
+ */
+#define bpf_core_type_size(type)					    \
+	__builtin_preserve_type_info(*(typeof(type) *)0, BPF_TYPE_SIZE)
+
+/*
+ * Convenience macro to check that provided enumerator value is defined in
+ * a target kernel.
+ * Returns:
+ *    1, if specified enum type and its enumerator value are present in target
+ *    kernel's BTF;
+ *    0, if no matching enum and/or enum value within that enum is found.
+ */
+#define bpf_core_enum_value_exists(enum_type, enum_value)		    \
+	__builtin_preserve_enum_value(*(typeof(enum_type) *)enum_value, BPF_ENUMVAL_EXISTS)
+
+/*
+ * Convenience macro to get the integer value of an enumerator value in
+ * a target kernel.
+ * Returns:
+ *    64-bit value, if specified enum type and its enumerator value are
+ *    present in target kernel's BTF;
+ *    0, if no matching enum and/or enum value within that enum is found.
+ */
+#define bpf_core_enum_value(enum_type, enum_value)			    \
+	__builtin_preserve_enum_value(*(typeof(enum_type) *)enum_value, BPF_ENUMVAL_VALUE)
+
+/*
+ * bpf_core_read() abstracts away bpf_probe_read_kernel() call and captures
+ * offset relocation for source address using __builtin_preserve_access_index()
+ * built-in, provided by Clang.
+ *
+ * __builtin_preserve_access_index() takes as an argument an expression of
+ * taking an address of a field within struct/union. It makes compiler emit
+ * a relocation, which records BTF type ID describing root struct/union and an
+ * accessor string which describes exact embedded field that was used to take
+ * an address. See detailed description of this relocation format and
+ * semantics in comments to struct bpf_field_reloc in libbpf_internal.h.
+ *
+ * This relocation allows libbpf to adjust BPF instruction to use correct
+ * actual field offset, based on target kernel BTF type that matches original
+ * (local) BTF, used to record relocation.
+ */
+#define bpf_core_read(dst, sz, src)					    \
+	bpf_probe_read_kernel(dst, sz, (const void *)__builtin_preserve_access_index(src))
+
+/* NOTE: see comments for BPF_CORE_READ_USER() about the proper types use. */
+#define bpf_core_read_user(dst, sz, src)				    \
+	bpf_probe_read_user(dst, sz, (const void *)__builtin_preserve_access_index(src))
+/*
+ * bpf_core_read_str() is a thin wrapper around bpf_probe_read_str()
+ * additionally emitting BPF CO-RE field relocation for specified source
+ * argument.
+ */
+#define bpf_core_read_str(dst, sz, src)					    \
+	bpf_probe_read_kernel_str(dst, sz, (const void *)__builtin_preserve_access_index(src))
+
+/* NOTE: see comments for BPF_CORE_READ_USER() about the proper types use. */
+#define bpf_core_read_user_str(dst, sz, src)				    \
+	bpf_probe_read_user_str(dst, sz, (const void *)__builtin_preserve_access_index(src))
+
+#define ___concat(a, b) a ## b
+#define ___apply(fn, n) ___concat(fn, n)
+#define ___nth(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, __11, N, ...) N
+
+/*
+ * return number of provided arguments; used for switch-based variadic macro
+ * definitions (see ___last, ___arrow, etc below)
+ */
+#define ___narg(...) ___nth(_, ##__VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
+/*
+ * return 0 if no arguments are passed, N - otherwise; used for
+ * recursively-defined macros to specify termination (0) case, and generic
+ * (N) case (e.g., ___read_ptrs, ___core_read)
+ */
+#define ___empty(...) ___nth(_, ##__VA_ARGS__, N, N, N, N, N, N, N, N, N, N, 0)
+
+#define ___last1(x) x
+#define ___last2(a, x) x
+#define ___last3(a, b, x) x
+#define ___last4(a, b, c, x) x
+#define ___last5(a, b, c, d, x) x
+#define ___last6(a, b, c, d, e, x) x
+#define ___last7(a, b, c, d, e, f, x) x
+#define ___last8(a, b, c, d, e, f, g, x) x
+#define ___last9(a, b, c, d, e, f, g, h, x) x
+#define ___last10(a, b, c, d, e, f, g, h, i, x) x
+#define ___last(...) ___apply(___last, ___narg(__VA_ARGS__))(__VA_ARGS__)
+
+#define ___nolast2(a, _) a
+#define ___nolast3(a, b, _) a, b
+#define ___nolast4(a, b, c, _) a, b, c
+#define ___nolast5(a, b, c, d, _) a, b, c, d
+#define ___nolast6(a, b, c, d, e, _) a, b, c, d, e
+#define ___nolast7(a, b, c, d, e, f, _) a, b, c, d, e, f
+#define ___nolast8(a, b, c, d, e, f, g, _) a, b, c, d, e, f, g
+#define ___nolast9(a, b, c, d, e, f, g, h, _) a, b, c, d, e, f, g, h
+#define ___nolast10(a, b, c, d, e, f, g, h, i, _) a, b, c, d, e, f, g, h, i
+#define ___nolast(...) ___apply(___nolast, ___narg(__VA_ARGS__))(__VA_ARGS__)
+
+#define ___arrow1(a) a
+#define ___arrow2(a, b) a->b
+#define ___arrow3(a, b, c) a->b->c
+#define ___arrow4(a, b, c, d) a->b->c->d
+#define ___arrow5(a, b, c, d, e) a->b->c->d->e
+#define ___arrow6(a, b, c, d, e, f) a->b->c->d->e->f
+#define ___arrow7(a, b, c, d, e, f, g) a->b->c->d->e->f->g
+#define ___arrow8(a, b, c, d, e, f, g, h) a->b->c->d->e->f->g->h
+#define ___arrow9(a, b, c, d, e, f, g, h, i) a->b->c->d->e->f->g->h->i
+#define ___arrow10(a, b, c, d, e, f, g, h, i, j) a->b->c->d->e->f->g->h->i->j
+#define ___arrow(...) ___apply(___arrow, ___narg(__VA_ARGS__))(__VA_ARGS__)
+
+#define ___type(...) typeof(___arrow(__VA_ARGS__))
+
+#define ___read(read_fn, dst, src_type, src, accessor)			    \
+	read_fn((void *)(dst), sizeof(*(dst)), &((src_type)(src))->accessor)
+
+/* "recursively" read a sequence of inner pointers using local __t var */
+#define ___rd_first(fn, src, a) ___read(fn, &__t, ___type(src), src, a);
+#define ___rd_last(fn, ...)						    \
+	___read(fn, &__t, ___type(___nolast(__VA_ARGS__)), __t, ___last(__VA_ARGS__));
+#define ___rd_p1(fn, ...) const void *__t; ___rd_first(fn, __VA_ARGS__)
+#define ___rd_p2(fn, ...) ___rd_p1(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__)
+#define ___rd_p3(fn, ...) ___rd_p2(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__)
+#define ___rd_p4(fn, ...) ___rd_p3(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__)
+#define ___rd_p5(fn, ...) ___rd_p4(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__)
+#define ___rd_p6(fn, ...) ___rd_p5(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__)
+#define ___rd_p7(fn, ...) ___rd_p6(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__)
+#define ___rd_p8(fn, ...) ___rd_p7(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__)
+#define ___rd_p9(fn, ...) ___rd_p8(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__)
+#define ___read_ptrs(fn, src, ...)					    \
+	___apply(___rd_p, ___narg(__VA_ARGS__))(fn, src, __VA_ARGS__)
+
+#define ___core_read0(fn, fn_ptr, dst, src, a)				    \
+	___read(fn, dst, ___type(src), src, a);
+#define ___core_readN(fn, fn_ptr, dst, src, ...)			    \
+	___read_ptrs(fn_ptr, src, ___nolast(__VA_ARGS__))		    \
+	___read(fn, dst, ___type(src, ___nolast(__VA_ARGS__)), __t,	    \
+		___last(__VA_ARGS__));
+#define ___core_read(fn, fn_ptr, dst, src, a, ...)			    \
+	___apply(___core_read, ___empty(__VA_ARGS__))(fn, fn_ptr, dst,	    \
+						      src, a, ##__VA_ARGS__)
+
+/*
+ * BPF_CORE_READ_INTO() is a more performance-conscious variant of
+ * BPF_CORE_READ(), in which final field is read into user-provided storage.
+ * See BPF_CORE_READ() below for more details on general usage.
+ */
+#define BPF_CORE_READ_INTO(dst, src, a, ...) ({				    \
+	___core_read(bpf_core_read, bpf_core_read,			    \
+		     dst, (src), a, ##__VA_ARGS__)			    \
+})
+
+/*
+ * Variant of BPF_CORE_READ_INTO() for reading from user-space memory.
+ *
+ * NOTE: see comments for BPF_CORE_READ_USER() about the proper types use.
+ */
+#define BPF_CORE_READ_USER_INTO(dst, src, a, ...) ({			    \
+	___core_read(bpf_core_read_user, bpf_core_read_user,		    \
+		     dst, (src), a, ##__VA_ARGS__)			    \
+})
+
+/* Non-CO-RE variant of BPF_CORE_READ_INTO() */
+#define BPF_PROBE_READ_INTO(dst, src, a, ...) ({			    \
+	___core_read(bpf_probe_read, bpf_probe_read,			    \
+		     dst, (src), a, ##__VA_ARGS__)			    \
+})
+
+/* Non-CO-RE variant of BPF_CORE_READ_USER_INTO().
+ *
+ * As no CO-RE relocations are emitted, source types can be arbitrary and are
+ * not restricted to kernel types only.
+ */
+#define BPF_PROBE_READ_USER_INTO(dst, src, a, ...) ({			    \
+	___core_read(bpf_probe_read_user, bpf_probe_read_user,		    \
+		     dst, (src), a, ##__VA_ARGS__)			    \
+})
+
+/*
+ * BPF_CORE_READ_STR_INTO() does same "pointer chasing" as
+ * BPF_CORE_READ() for intermediate pointers, but then executes (and returns
+ * corresponding error code) bpf_core_read_str() for final string read.
+ */
+#define BPF_CORE_READ_STR_INTO(dst, src, a, ...) ({			    \
+	___core_read(bpf_core_read_str, bpf_core_read,			    \
+		     dst, (src), a, ##__VA_ARGS__)			    \
+})
+
+/*
+ * Variant of BPF_CORE_READ_STR_INTO() for reading from user-space memory.
+ *
+ * NOTE: see comments for BPF_CORE_READ_USER() about the proper types use.
+ */
+#define BPF_CORE_READ_USER_STR_INTO(dst, src, a, ...) ({		    \
+	___core_read(bpf_core_read_user_str, bpf_core_read_user,	    \
+		     dst, (src), a, ##__VA_ARGS__)			    \
+})
+
+/* Non-CO-RE variant of BPF_CORE_READ_STR_INTO() */
+#define BPF_PROBE_READ_STR_INTO(dst, src, a, ...) ({			    \
+	___core_read(bpf_probe_read_str, bpf_probe_read,		    \
+		     dst, (src), a, ##__VA_ARGS__)			    \
+})
+
+/*
+ * Non-CO-RE variant of BPF_CORE_READ_USER_STR_INTO().
+ *
+ * As no CO-RE relocations are emitted, source types can be arbitrary and are
+ * not restricted to kernel types only.
+ */
+#define BPF_PROBE_READ_USER_STR_INTO(dst, src, a, ...) ({		    \
+	___core_read(bpf_probe_read_user_str, bpf_probe_read_user,	    \
+		     dst, (src), a, ##__VA_ARGS__)			    \
+})
+
+/*
+ * BPF_CORE_READ() is used to simplify BPF CO-RE relocatable read, especially
+ * when there are few pointer chasing steps.
+ * E.g., what in non-BPF world (or in BPF w/ BCC) would be something like:
+ *	int x = s->a.b.c->d.e->f->g;
+ * can be succinctly achieved using BPF_CORE_READ as:
+ *	int x = BPF_CORE_READ(s, a.b.c, d.e, f, g);
+ *
+ * BPF_CORE_READ will decompose above statement into 4 bpf_core_read (BPF
+ * CO-RE relocatable bpf_probe_read_kernel() wrapper) calls, logically
+ * equivalent to:
+ * 1. const void *__t = s->a.b.c;
+ * 2. __t = __t->d.e;
+ * 3. __t = __t->f;
+ * 4. return __t->g;
+ *
+ * Equivalence is logical, because there is a heavy type casting/preservation
+ * involved, as well as all the reads are happening through
+ * bpf_probe_read_kernel() calls using __builtin_preserve_access_index() to
+ * emit CO-RE relocations.
+ *
+ * N.B. Only up to 9 "field accessors" are supported, which should be more
+ * than enough for any practical purpose.
+ */
+#define BPF_CORE_READ(src, a, ...) ({					    \
+	___type((src), a, ##__VA_ARGS__) __r;				    \
+	BPF_CORE_READ_INTO(&__r, (src), a, ##__VA_ARGS__);		    \
+	__r;								    \
+})
+
+/*
+ * Variant of BPF_CORE_READ() for reading from user-space memory.
+ *
+ * NOTE: all the source types involved are still *kernel types* and need to
+ * exist in kernel (or kernel module) BTF, otherwise CO-RE relocation will
+ * fail. Custom user types are not relocatable with CO-RE.
+ * The typical situation in which BPF_CORE_READ_USER() might be used is to
+ * read kernel UAPI types from the user-space memory passed in as a syscall
+ * input argument.
+ */
+#define BPF_CORE_READ_USER(src, a, ...) ({				    \
+	___type((src), a, ##__VA_ARGS__) __r;				    \
+	BPF_CORE_READ_USER_INTO(&__r, (src), a, ##__VA_ARGS__);		    \
+	__r;								    \
+})
+
+/* Non-CO-RE variant of BPF_CORE_READ() */
+#define BPF_PROBE_READ(src, a, ...) ({					    \
+	___type((src), a, ##__VA_ARGS__) __r;				    \
+	BPF_PROBE_READ_INTO(&__r, (src), a, ##__VA_ARGS__);		    \
+	__r;								    \
+})
+
+/*
+ * Non-CO-RE variant of BPF_CORE_READ_USER().
+ *
+ * As no CO-RE relocations are emitted, source types can be arbitrary and are
+ * not restricted to kernel types only.
+ */
+#define BPF_PROBE_READ_USER(src, a, ...) ({				    \
+	___type((src), a, ##__VA_ARGS__) __r;				    \
+	BPF_PROBE_READ_USER_INTO(&__r, (src), a, ##__VA_ARGS__);	    \
+	__r;								    \
+})
+
+#endif
+
diff --git a/src/bpf_endian.h b/src/bpf_endian.h
new file mode 100644
index 0000000..ec9db4f
--- /dev/null
+++ b/src/bpf_endian.h
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __BPF_ENDIAN__
+#define __BPF_ENDIAN__
+
+/*
+ * Isolate byte #n and put it into byte #m, for __u##b type.
+ * E.g., moving byte #6 (nnnnnnnn) into byte #1 (mmmmmmmm) for __u64:
+ * 1) xxxxxxxx nnnnnnnn xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx mmmmmmmm xxxxxxxx
+ * 2) nnnnnnnn xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx mmmmmmmm xxxxxxxx 00000000
+ * 3) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 nnnnnnnn
+ * 4) 00000000 00000000 00000000 00000000 00000000 00000000 nnnnnnnn 00000000
+ */
+#define ___bpf_mvb(x, b, n, m) ((__u##b)(x) << (b-(n+1)*8) >> (b-8) << (m*8))
+
+#define ___bpf_swab16(x) ((__u16)(			\
+			  ___bpf_mvb(x, 16, 0, 1) |	\
+			  ___bpf_mvb(x, 16, 1, 0)))
+
+#define ___bpf_swab32(x) ((__u32)(			\
+			  ___bpf_mvb(x, 32, 0, 3) |	\
+			  ___bpf_mvb(x, 32, 1, 2) |	\
+			  ___bpf_mvb(x, 32, 2, 1) |	\
+			  ___bpf_mvb(x, 32, 3, 0)))
+
+#define ___bpf_swab64(x) ((__u64)(			\
+			  ___bpf_mvb(x, 64, 0, 7) |	\
+			  ___bpf_mvb(x, 64, 1, 6) |	\
+			  ___bpf_mvb(x, 64, 2, 5) |	\
+			  ___bpf_mvb(x, 64, 3, 4) |	\
+			  ___bpf_mvb(x, 64, 4, 3) |	\
+			  ___bpf_mvb(x, 64, 5, 2) |	\
+			  ___bpf_mvb(x, 64, 6, 1) |	\
+			  ___bpf_mvb(x, 64, 7, 0)))
+
+/* LLVM's BPF target selects the endianness of the CPU
+ * it compiles on, or the user specifies (bpfel/bpfeb),
+ * respectively. The used __BYTE_ORDER__ is defined by
+ * the compiler, we cannot rely on __BYTE_ORDER from
+ * libc headers, since it doesn't reflect the actual
+ * requested byte order.
+ *
+ * Note, LLVM's BPF target has different __builtin_bswapX()
+ * semantics. It does map to BPF_ALU | BPF_END | BPF_TO_BE
+ * in bpfel and bpfeb case, which means below, that we map
+ * to cpu_to_be16(). We could use it unconditionally in BPF
+ * case, but better not rely on it, so that this header here
+ * can be used from application and BPF program side, which
+ * use different targets.
+ */
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+# define __bpf_ntohs(x)			__builtin_bswap16(x)
+# define __bpf_htons(x)			__builtin_bswap16(x)
+# define __bpf_constant_ntohs(x)	___bpf_swab16(x)
+# define __bpf_constant_htons(x)	___bpf_swab16(x)
+# define __bpf_ntohl(x)			__builtin_bswap32(x)
+# define __bpf_htonl(x)			__builtin_bswap32(x)
+# define __bpf_constant_ntohl(x)	___bpf_swab32(x)
+# define __bpf_constant_htonl(x)	___bpf_swab32(x)
+# define __bpf_be64_to_cpu(x)		__builtin_bswap64(x)
+# define __bpf_cpu_to_be64(x)		__builtin_bswap64(x)
+# define __bpf_constant_be64_to_cpu(x)	___bpf_swab64(x)
+# define __bpf_constant_cpu_to_be64(x)	___bpf_swab64(x)
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+# define __bpf_ntohs(x)			(x)
+# define __bpf_htons(x)			(x)
+# define __bpf_constant_ntohs(x)	(x)
+# define __bpf_constant_htons(x)	(x)
+# define __bpf_ntohl(x)			(x)
+# define __bpf_htonl(x)			(x)
+# define __bpf_constant_ntohl(x)	(x)
+# define __bpf_constant_htonl(x)	(x)
+# define __bpf_be64_to_cpu(x)		(x)
+# define __bpf_cpu_to_be64(x)		(x)
+# define __bpf_constant_be64_to_cpu(x)  (x)
+# define __bpf_constant_cpu_to_be64(x)  (x)
+#else
+# error "Fix your compiler's __BYTE_ORDER__?!"
+#endif
+
+#define bpf_htons(x)				\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_htons(x) : __bpf_htons(x))
+#define bpf_ntohs(x)				\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_ntohs(x) : __bpf_ntohs(x))
+#define bpf_htonl(x)				\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_htonl(x) : __bpf_htonl(x))
+#define bpf_ntohl(x)				\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_ntohl(x) : __bpf_ntohl(x))
+#define bpf_cpu_to_be64(x)			\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_cpu_to_be64(x) : __bpf_cpu_to_be64(x))
+#define bpf_be64_to_cpu(x)			\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_be64_to_cpu(x) : __bpf_be64_to_cpu(x))
+
+#endif /* __BPF_ENDIAN__ */
diff --git a/src/bpf_gen_internal.h b/src/bpf_gen_internal.h
new file mode 100644
index 0000000..2233089
--- /dev/null
+++ b/src/bpf_gen_internal.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/* Copyright (c) 2021 Facebook */
+#ifndef __BPF_GEN_INTERNAL_H
+#define __BPF_GEN_INTERNAL_H
+
+#include "bpf.h"
+
+struct ksym_relo_desc {
+	const char *name;
+	int kind;
+	int insn_idx;
+	bool is_weak;
+	bool is_typeless;
+};
+
+struct ksym_desc {
+	const char *name;
+	int ref;
+	int kind;
+	union {
+		/* used for kfunc */
+		int off;
+		/* used for typeless ksym */
+		bool typeless;
+	};
+	int insn;
+};
+
+struct bpf_gen {
+	struct gen_loader_opts *opts;
+	void *data_start;
+	void *data_cur;
+	void *insn_start;
+	void *insn_cur;
+	ssize_t cleanup_label;
+	__u32 nr_progs;
+	__u32 nr_maps;
+	int log_level;
+	int error;
+	struct ksym_relo_desc *relos;
+	int relo_cnt;
+	struct bpf_core_relo *core_relos;
+	int core_relo_cnt;
+	char attach_target[128];
+	int attach_kind;
+	struct ksym_desc *ksyms;
+	__u32 nr_ksyms;
+	int fd_array;
+	int nr_fd_array;
+};
+
+void bpf_gen__init(struct bpf_gen *gen, int log_level, int nr_progs, int nr_maps);
+int bpf_gen__finish(struct bpf_gen *gen, int nr_progs, int nr_maps);
+void bpf_gen__free(struct bpf_gen *gen);
+void bpf_gen__load_btf(struct bpf_gen *gen, const void *raw_data, __u32 raw_size);
+void bpf_gen__map_create(struct bpf_gen *gen,
+			 enum bpf_map_type map_type, const char *map_name,
+			 __u32 key_size, __u32 value_size, __u32 max_entries,
+			 struct bpf_map_create_opts *map_attr, int map_idx);
+void bpf_gen__prog_load(struct bpf_gen *gen,
+			enum bpf_prog_type prog_type, const char *prog_name,
+			const char *license, struct bpf_insn *insns, size_t insn_cnt,
+			struct bpf_prog_load_opts *load_attr, int prog_idx);
+void bpf_gen__map_update_elem(struct bpf_gen *gen, int map_idx, void *value, __u32 value_size);
+void bpf_gen__map_freeze(struct bpf_gen *gen, int map_idx);
+void bpf_gen__record_attach_target(struct bpf_gen *gen, const char *name, enum bpf_attach_type type);
+void bpf_gen__record_extern(struct bpf_gen *gen, const char *name, bool is_weak,
+			    bool is_typeless, int kind, int insn_idx);
+void bpf_gen__record_relo_core(struct bpf_gen *gen, const struct bpf_core_relo *core_relo);
+void bpf_gen__populate_outer_map(struct bpf_gen *gen, int outer_map_idx, int key, int inner_map_idx);
+
+#endif
diff --git a/src/bpf_helper_defs.h b/src/bpf_helper_defs.h
new file mode 100644
index 0000000..9bcaca1
--- /dev/null
+++ b/src/bpf_helper_defs.h
@@ -0,0 +1,4718 @@
+/* This is auto-generated file. See bpf_doc.py for details. */
+
+/* Forward declarations of BPF structs */
+struct bpf_fib_lookup;
+struct bpf_sk_lookup;
+struct bpf_perf_event_data;
+struct bpf_perf_event_value;
+struct bpf_pidns_info;
+struct bpf_redir_neigh;
+struct bpf_sock;
+struct bpf_sock_addr;
+struct bpf_sock_ops;
+struct bpf_sock_tuple;
+struct bpf_spin_lock;
+struct bpf_sysctl;
+struct bpf_tcp_sock;
+struct bpf_tunnel_key;
+struct bpf_xfrm_state;
+struct linux_binprm;
+struct pt_regs;
+struct sk_reuseport_md;
+struct sockaddr;
+struct tcphdr;
+struct seq_file;
+struct tcp6_sock;
+struct tcp_sock;
+struct tcp_timewait_sock;
+struct tcp_request_sock;
+struct udp6_sock;
+struct unix_sock;
+struct task_struct;
+struct cgroup;
+struct __sk_buff;
+struct sk_msg_md;
+struct xdp_md;
+struct path;
+struct btf_ptr;
+struct inode;
+struct socket;
+struct file;
+struct bpf_timer;
+struct mptcp_sock;
+struct bpf_dynptr;
+struct iphdr;
+struct ipv6hdr;
+
+/*
+ * bpf_map_lookup_elem
+ *
+ * 	Perform a lookup in *map* for an entry associated to *key*.
+ *
+ * Returns
+ * 	Map value associated to *key*, or **NULL** if no entry was
+ * 	found.
+ */
+static void *(*bpf_map_lookup_elem)(void *map, const void *key) = (void *) 1;
+
+/*
+ * bpf_map_update_elem
+ *
+ * 	Add or update the value of the entry associated to *key* in
+ * 	*map* with *value*. *flags* is one of:
+ *
+ * 	**BPF_NOEXIST**
+ * 		The entry for *key* must not exist in the map.
+ * 	**BPF_EXIST**
+ * 		The entry for *key* must already exist in the map.
+ * 	**BPF_ANY**
+ * 		No condition on the existence of the entry for *key*.
+ *
+ * 	Flag value **BPF_NOEXIST** cannot be used for maps of types
+ * 	**BPF_MAP_TYPE_ARRAY** or **BPF_MAP_TYPE_PERCPU_ARRAY**  (all
+ * 	elements always exist), the helper would return an error.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_map_update_elem)(void *map, const void *key, const void *value, __u64 flags) = (void *) 2;
+
+/*
+ * bpf_map_delete_elem
+ *
+ * 	Delete entry with *key* from *map*.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_map_delete_elem)(void *map, const void *key) = (void *) 3;
+
+/*
+ * bpf_probe_read
+ *
+ * 	For tracing programs, safely attempt to read *size* bytes from
+ * 	kernel space address *unsafe_ptr* and store the data in *dst*.
+ *
+ * 	Generally, use **bpf_probe_read_user**\ () or
+ * 	**bpf_probe_read_kernel**\ () instead.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_probe_read)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 4;
+
+/*
+ * bpf_ktime_get_ns
+ *
+ * 	Return the time elapsed since system boot, in nanoseconds.
+ * 	Does not include time the system was suspended.
+ * 	See: **clock_gettime**\ (**CLOCK_MONOTONIC**)
+ *
+ * Returns
+ * 	Current *ktime*.
+ */
+static __u64 (*bpf_ktime_get_ns)(void) = (void *) 5;
+
+/*
+ * bpf_trace_printk
+ *
+ * 	This helper is a "printk()-like" facility for debugging. It
+ * 	prints a message defined by format *fmt* (of size *fmt_size*)
+ * 	to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
+ * 	available. It can take up to three additional **u64**
+ * 	arguments (as an eBPF helpers, the total number of arguments is
+ * 	limited to five).
+ *
+ * 	Each time the helper is called, it appends a line to the trace.
+ * 	Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
+ * 	open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
+ * 	The format of the trace is customizable, and the exact output
+ * 	one will get depends on the options set in
+ * 	*\/sys/kernel/debug/tracing/trace_options* (see also the
+ * 	*README* file under the same directory). However, it usually
+ * 	defaults to something like:
+ *
+ * 	::
+ *
+ * 		telnet-470   [001] .N.. 419421.045894: 0x00000001: <formatted msg>
+ *
+ * 	In the above:
+ *
+ * 		* ``telnet`` is the name of the current task.
+ * 		* ``470`` is the PID of the current task.
+ * 		* ``001`` is the CPU number on which the task is
+ * 		  running.
+ * 		* In ``.N..``, each character refers to a set of
+ * 		  options (whether irqs are enabled, scheduling
+ * 		  options, whether hard/softirqs are running, level of
+ * 		  preempt_disabled respectively). **N** means that
+ * 		  **TIF_NEED_RESCHED** and **PREEMPT_NEED_RESCHED**
+ * 		  are set.
+ * 		* ``419421.045894`` is a timestamp.
+ * 		* ``0x00000001`` is a fake value used by BPF for the
+ * 		  instruction pointer register.
+ * 		* ``<formatted msg>`` is the message formatted with
+ * 		  *fmt*.
+ *
+ * 	The conversion specifiers supported by *fmt* are similar, but
+ * 	more limited than for printk(). They are **%d**, **%i**,
+ * 	**%u**, **%x**, **%ld**, **%li**, **%lu**, **%lx**, **%lld**,
+ * 	**%lli**, **%llu**, **%llx**, **%p**, **%s**. No modifier (size
+ * 	of field, padding with zeroes, etc.) is available, and the
+ * 	helper will return **-EINVAL** (but print nothing) if it
+ * 	encounters an unknown specifier.
+ *
+ * 	Also, note that **bpf_trace_printk**\ () is slow, and should
+ * 	only be used for debugging purposes. For this reason, a notice
+ * 	block (spanning several lines) is printed to kernel logs and
+ * 	states that the helper should not be used "for production use"
+ * 	the first time this helper is used (or more precisely, when
+ * 	**trace_printk**\ () buffers are allocated). For passing values
+ * 	to user space, perf events should be preferred.
+ *
+ * Returns
+ * 	The number of bytes written to the buffer, or a negative error
+ * 	in case of failure.
+ */
+static long (*bpf_trace_printk)(const char *fmt, __u32 fmt_size, ...) = (void *) 6;
+
+/*
+ * bpf_get_prandom_u32
+ *
+ * 	Get a pseudo-random number.
+ *
+ * 	From a security point of view, this helper uses its own
+ * 	pseudo-random internal state, and cannot be used to infer the
+ * 	seed of other random functions in the kernel. However, it is
+ * 	essential to note that the generator used by the helper is not
+ * 	cryptographically secure.
+ *
+ * Returns
+ * 	A random 32-bit unsigned value.
+ */
+static __u32 (*bpf_get_prandom_u32)(void) = (void *) 7;
+
+/*
+ * bpf_get_smp_processor_id
+ *
+ * 	Get the SMP (symmetric multiprocessing) processor id. Note that
+ * 	all programs run with migration disabled, which means that the
+ * 	SMP processor id is stable during all the execution of the
+ * 	program.
+ *
+ * Returns
+ * 	The SMP id of the processor running the program.
+ */
+static __u32 (*bpf_get_smp_processor_id)(void) = (void *) 8;
+
+/*
+ * bpf_skb_store_bytes
+ *
+ * 	Store *len* bytes from address *from* into the packet
+ * 	associated to *skb*, at *offset*. *flags* are a combination of
+ * 	**BPF_F_RECOMPUTE_CSUM** (automatically recompute the
+ * 	checksum for the packet after storing the bytes) and
+ * 	**BPF_F_INVALIDATE_HASH** (set *skb*\ **->hash**, *skb*\
+ * 	**->swhash** and *skb*\ **->l4hash** to 0).
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_store_bytes)(struct __sk_buff *skb, __u32 offset, const void *from, __u32 len, __u64 flags) = (void *) 9;
+
+/*
+ * bpf_l3_csum_replace
+ *
+ * 	Recompute the layer 3 (e.g. IP) checksum for the packet
+ * 	associated to *skb*. Computation is incremental, so the helper
+ * 	must know the former value of the header field that was
+ * 	modified (*from*), the new value of this field (*to*), and the
+ * 	number of bytes (2 or 4) for this field, stored in *size*.
+ * 	Alternatively, it is possible to store the difference between
+ * 	the previous and the new values of the header field in *to*, by
+ * 	setting *from* and *size* to 0. For both methods, *offset*
+ * 	indicates the location of the IP checksum within the packet.
+ *
+ * 	This helper works in combination with **bpf_csum_diff**\ (),
+ * 	which does not update the checksum in-place, but offers more
+ * 	flexibility and can handle sizes larger than 2 or 4 for the
+ * 	checksum to update.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_l3_csum_replace)(struct __sk_buff *skb, __u32 offset, __u64 from, __u64 to, __u64 size) = (void *) 10;
+
+/*
+ * bpf_l4_csum_replace
+ *
+ * 	Recompute the layer 4 (e.g. TCP, UDP or ICMP) checksum for the
+ * 	packet associated to *skb*. Computation is incremental, so the
+ * 	helper must know the former value of the header field that was
+ * 	modified (*from*), the new value of this field (*to*), and the
+ * 	number of bytes (2 or 4) for this field, stored on the lowest
+ * 	four bits of *flags*. Alternatively, it is possible to store
+ * 	the difference between the previous and the new values of the
+ * 	header field in *to*, by setting *from* and the four lowest
+ * 	bits of *flags* to 0. For both methods, *offset* indicates the
+ * 	location of the IP checksum within the packet. In addition to
+ * 	the size of the field, *flags* can be added (bitwise OR) actual
+ * 	flags. With **BPF_F_MARK_MANGLED_0**, a null checksum is left
+ * 	untouched (unless **BPF_F_MARK_ENFORCE** is added as well), and
+ * 	for updates resulting in a null checksum the value is set to
+ * 	**CSUM_MANGLED_0** instead. Flag **BPF_F_PSEUDO_HDR** indicates
+ * 	the checksum is to be computed against a pseudo-header.
+ *
+ * 	This helper works in combination with **bpf_csum_diff**\ (),
+ * 	which does not update the checksum in-place, but offers more
+ * 	flexibility and can handle sizes larger than 2 or 4 for the
+ * 	checksum to update.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_l4_csum_replace)(struct __sk_buff *skb, __u32 offset, __u64 from, __u64 to, __u64 flags) = (void *) 11;
+
+/*
+ * bpf_tail_call
+ *
+ * 	This special helper is used to trigger a "tail call", or in
+ * 	other words, to jump into another eBPF program. The same stack
+ * 	frame is used (but values on stack and in registers for the
+ * 	caller are not accessible to the callee). This mechanism allows
+ * 	for program chaining, either for raising the maximum number of
+ * 	available eBPF instructions, or to execute given programs in
+ * 	conditional blocks. For security reasons, there is an upper
+ * 	limit to the number of successive tail calls that can be
+ * 	performed.
+ *
+ * 	Upon call of this helper, the program attempts to jump into a
+ * 	program referenced at index *index* in *prog_array_map*, a
+ * 	special map of type **BPF_MAP_TYPE_PROG_ARRAY**, and passes
+ * 	*ctx*, a pointer to the context.
+ *
+ * 	If the call succeeds, the kernel immediately runs the first
+ * 	instruction of the new program. This is not a function call,
+ * 	and it never returns to the previous program. If the call
+ * 	fails, then the helper has no effect, and the caller continues
+ * 	to run its subsequent instructions. A call can fail if the
+ * 	destination program for the jump does not exist (i.e. *index*
+ * 	is superior to the number of entries in *prog_array_map*), or
+ * 	if the maximum number of tail calls has been reached for this
+ * 	chain of programs. This limit is defined in the kernel by the
+ * 	macro **MAX_TAIL_CALL_CNT** (not accessible to user space),
+ * 	which is currently set to 33.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_tail_call)(void *ctx, void *prog_array_map, __u32 index) = (void *) 12;
+
+/*
+ * bpf_clone_redirect
+ *
+ * 	Clone and redirect the packet associated to *skb* to another
+ * 	net device of index *ifindex*. Both ingress and egress
+ * 	interfaces can be used for redirection. The **BPF_F_INGRESS**
+ * 	value in *flags* is used to make the distinction (ingress path
+ * 	is selected if the flag is present, egress path otherwise).
+ * 	This is the only flag supported for now.
+ *
+ * 	In comparison with **bpf_redirect**\ () helper,
+ * 	**bpf_clone_redirect**\ () has the associated cost of
+ * 	duplicating the packet buffer, but this can be executed out of
+ * 	the eBPF program. Conversely, **bpf_redirect**\ () is more
+ * 	efficient, but it is handled through an action code where the
+ * 	redirection happens only after the eBPF program has returned.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_clone_redirect)(struct __sk_buff *skb, __u32 ifindex, __u64 flags) = (void *) 13;
+
+/*
+ * bpf_get_current_pid_tgid
+ *
+ * 	Get the current pid and tgid.
+ *
+ * Returns
+ * 	A 64-bit integer containing the current tgid and pid, and
+ * 	created as such:
+ * 	*current_task*\ **->tgid << 32 \|**
+ * 	*current_task*\ **->pid**.
+ */
+static __u64 (*bpf_get_current_pid_tgid)(void) = (void *) 14;
+
+/*
+ * bpf_get_current_uid_gid
+ *
+ * 	Get the current uid and gid.
+ *
+ * Returns
+ * 	A 64-bit integer containing the current GID and UID, and
+ * 	created as such: *current_gid* **<< 32 \|** *current_uid*.
+ */
+static __u64 (*bpf_get_current_uid_gid)(void) = (void *) 15;
+
+/*
+ * bpf_get_current_comm
+ *
+ * 	Copy the **comm** attribute of the current task into *buf* of
+ * 	*size_of_buf*. The **comm** attribute contains the name of
+ * 	the executable (excluding the path) for the current task. The
+ * 	*size_of_buf* must be strictly positive. On success, the
+ * 	helper makes sure that the *buf* is NUL-terminated. On failure,
+ * 	it is filled with zeroes.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_get_current_comm)(void *buf, __u32 size_of_buf) = (void *) 16;
+
+/*
+ * bpf_get_cgroup_classid
+ *
+ * 	Retrieve the classid for the current task, i.e. for the net_cls
+ * 	cgroup to which *skb* belongs.
+ *
+ * 	This helper can be used on TC egress path, but not on ingress.
+ *
+ * 	The net_cls cgroup provides an interface to tag network packets
+ * 	based on a user-provided identifier for all traffic coming from
+ * 	the tasks belonging to the related cgroup. See also the related
+ * 	kernel documentation, available from the Linux sources in file
+ * 	*Documentation/admin-guide/cgroup-v1/net_cls.rst*.
+ *
+ * 	The Linux kernel has two versions for cgroups: there are
+ * 	cgroups v1 and cgroups v2. Both are available to users, who can
+ * 	use a mixture of them, but note that the net_cls cgroup is for
+ * 	cgroup v1 only. This makes it incompatible with BPF programs
+ * 	run on cgroups, which is a cgroup-v2-only feature (a socket can
+ * 	only hold data for one version of cgroups at a time).
+ *
+ * 	This helper is only available is the kernel was compiled with
+ * 	the **CONFIG_CGROUP_NET_CLASSID** configuration option set to
+ * 	"**y**" or to "**m**".
+ *
+ * Returns
+ * 	The classid, or 0 for the default unconfigured classid.
+ */
+static __u32 (*bpf_get_cgroup_classid)(struct __sk_buff *skb) = (void *) 17;
+
+/*
+ * bpf_skb_vlan_push
+ *
+ * 	Push a *vlan_tci* (VLAN tag control information) of protocol
+ * 	*vlan_proto* to the packet associated to *skb*, then update
+ * 	the checksum. Note that if *vlan_proto* is different from
+ * 	**ETH_P_8021Q** and **ETH_P_8021AD**, it is considered to
+ * 	be **ETH_P_8021Q**.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_vlan_push)(struct __sk_buff *skb, __be16 vlan_proto, __u16 vlan_tci) = (void *) 18;
+
+/*
+ * bpf_skb_vlan_pop
+ *
+ * 	Pop a VLAN header from the packet associated to *skb*.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_vlan_pop)(struct __sk_buff *skb) = (void *) 19;
+
+/*
+ * bpf_skb_get_tunnel_key
+ *
+ * 	Get tunnel metadata. This helper takes a pointer *key* to an
+ * 	empty **struct bpf_tunnel_key** of **size**, that will be
+ * 	filled with tunnel metadata for the packet associated to *skb*.
+ * 	The *flags* can be set to **BPF_F_TUNINFO_IPV6**, which
+ * 	indicates that the tunnel is based on IPv6 protocol instead of
+ * 	IPv4.
+ *
+ * 	The **struct bpf_tunnel_key** is an object that generalizes the
+ * 	principal parameters used by various tunneling protocols into a
+ * 	single struct. This way, it can be used to easily make a
+ * 	decision based on the contents of the encapsulation header,
+ * 	"summarized" in this struct. In particular, it holds the IP
+ * 	address of the remote end (IPv4 or IPv6, depending on the case)
+ * 	in *key*\ **->remote_ipv4** or *key*\ **->remote_ipv6**. Also,
+ * 	this struct exposes the *key*\ **->tunnel_id**, which is
+ * 	generally mapped to a VNI (Virtual Network Identifier), making
+ * 	it programmable together with the **bpf_skb_set_tunnel_key**\
+ * 	() helper.
+ *
+ * 	Let's imagine that the following code is part of a program
+ * 	attached to the TC ingress interface, on one end of a GRE
+ * 	tunnel, and is supposed to filter out all messages coming from
+ * 	remote ends with IPv4 address other than 10.0.0.1:
+ *
+ * 	::
+ *
+ * 		int ret;
+ * 		struct bpf_tunnel_key key = {};
+ *
+ * 		ret = bpf_skb_get_tunnel_key(skb, &key, sizeof(key), 0);
+ * 		if (ret < 0)
+ * 			return TC_ACT_SHOT;	// drop packet
+ *
+ * 		if (key.remote_ipv4 != 0x0a000001)
+ * 			return TC_ACT_SHOT;	// drop packet
+ *
+ * 		return TC_ACT_OK;		// accept packet
+ *
+ * 	This interface can also be used with all encapsulation devices
+ * 	that can operate in "collect metadata" mode: instead of having
+ * 	one network device per specific configuration, the "collect
+ * 	metadata" mode only requires a single device where the
+ * 	configuration can be extracted from this helper.
+ *
+ * 	This can be used together with various tunnels such as VXLan,
+ * 	Geneve, GRE or IP in IP (IPIP).
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_get_tunnel_key)(struct __sk_buff *skb, struct bpf_tunnel_key *key, __u32 size, __u64 flags) = (void *) 20;
+
+/*
+ * bpf_skb_set_tunnel_key
+ *
+ * 	Populate tunnel metadata for packet associated to *skb.* The
+ * 	tunnel metadata is set to the contents of *key*, of *size*. The
+ * 	*flags* can be set to a combination of the following values:
+ *
+ * 	**BPF_F_TUNINFO_IPV6**
+ * 		Indicate that the tunnel is based on IPv6 protocol
+ * 		instead of IPv4.
+ * 	**BPF_F_ZERO_CSUM_TX**
+ * 		For IPv4 packets, add a flag to tunnel metadata
+ * 		indicating that checksum computation should be skipped
+ * 		and checksum set to zeroes.
+ * 	**BPF_F_DONT_FRAGMENT**
+ * 		Add a flag to tunnel metadata indicating that the
+ * 		packet should not be fragmented.
+ * 	**BPF_F_SEQ_NUMBER**
+ * 		Add a flag to tunnel metadata indicating that a
+ * 		sequence number should be added to tunnel header before
+ * 		sending the packet. This flag was added for GRE
+ * 		encapsulation, but might be used with other protocols
+ * 		as well in the future.
+ * 	**BPF_F_NO_TUNNEL_KEY**
+ * 		Add a flag to tunnel metadata indicating that no tunnel
+ * 		key should be set in the resulting tunnel header.
+ *
+ * 	Here is a typical usage on the transmit path:
+ *
+ * 	::
+ *
+ * 		struct bpf_tunnel_key key;
+ * 		     populate key ...
+ * 		bpf_skb_set_tunnel_key(skb, &key, sizeof(key), 0);
+ * 		bpf_clone_redirect(skb, vxlan_dev_ifindex, 0);
+ *
+ * 	See also the description of the **bpf_skb_get_tunnel_key**\ ()
+ * 	helper for additional information.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_set_tunnel_key)(struct __sk_buff *skb, struct bpf_tunnel_key *key, __u32 size, __u64 flags) = (void *) 21;
+
+/*
+ * bpf_perf_event_read
+ *
+ * 	Read the value of a perf event counter. This helper relies on a
+ * 	*map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of
+ * 	the perf event counter is selected when *map* is updated with
+ * 	perf event file descriptors. The *map* is an array whose size
+ * 	is the number of available CPUs, and each cell contains a value
+ * 	relative to one CPU. The value to retrieve is indicated by
+ * 	*flags*, that contains the index of the CPU to look up, masked
+ * 	with **BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
+ * 	**BPF_F_CURRENT_CPU** to indicate that the value for the
+ * 	current CPU should be retrieved.
+ *
+ * 	Note that before Linux 4.13, only hardware perf event can be
+ * 	retrieved.
+ *
+ * 	Also, be aware that the newer helper
+ * 	**bpf_perf_event_read_value**\ () is recommended over
+ * 	**bpf_perf_event_read**\ () in general. The latter has some ABI
+ * 	quirks where error and counter value are used as a return code
+ * 	(which is wrong to do since ranges may overlap). This issue is
+ * 	fixed with **bpf_perf_event_read_value**\ (), which at the same
+ * 	time provides more features over the **bpf_perf_event_read**\
+ * 	() interface. Please refer to the description of
+ * 	**bpf_perf_event_read_value**\ () for details.
+ *
+ * Returns
+ * 	The value of the perf event counter read from the map, or a
+ * 	negative error code in case of failure.
+ */
+static __u64 (*bpf_perf_event_read)(void *map, __u64 flags) = (void *) 22;
+
+/*
+ * bpf_redirect
+ *
+ * 	Redirect the packet to another net device of index *ifindex*.
+ * 	This helper is somewhat similar to **bpf_clone_redirect**\
+ * 	(), except that the packet is not cloned, which provides
+ * 	increased performance.
+ *
+ * 	Except for XDP, both ingress and egress interfaces can be used
+ * 	for redirection. The **BPF_F_INGRESS** value in *flags* is used
+ * 	to make the distinction (ingress path is selected if the flag
+ * 	is present, egress path otherwise). Currently, XDP only
+ * 	supports redirection to the egress interface, and accepts no
+ * 	flag at all.
+ *
+ * 	The same effect can also be attained with the more generic
+ * 	**bpf_redirect_map**\ (), which uses a BPF map to store the
+ * 	redirect target instead of providing it directly to the helper.
+ *
+ * Returns
+ * 	For XDP, the helper returns **XDP_REDIRECT** on success or
+ * 	**XDP_ABORTED** on error. For other program types, the values
+ * 	are **TC_ACT_REDIRECT** on success or **TC_ACT_SHOT** on
+ * 	error.
+ */
+static long (*bpf_redirect)(__u32 ifindex, __u64 flags) = (void *) 23;
+
+/*
+ * bpf_get_route_realm
+ *
+ * 	Retrieve the realm or the route, that is to say the
+ * 	**tclassid** field of the destination for the *skb*. The
+ * 	identifier retrieved is a user-provided tag, similar to the
+ * 	one used with the net_cls cgroup (see description for
+ * 	**bpf_get_cgroup_classid**\ () helper), but here this tag is
+ * 	held by a route (a destination entry), not by a task.
+ *
+ * 	Retrieving this identifier works with the clsact TC egress hook
+ * 	(see also **tc-bpf(8)**), or alternatively on conventional
+ * 	classful egress qdiscs, but not on TC ingress path. In case of
+ * 	clsact TC egress hook, this has the advantage that, internally,
+ * 	the destination entry has not been dropped yet in the transmit
+ * 	path. Therefore, the destination entry does not need to be
+ * 	artificially held via **netif_keep_dst**\ () for a classful
+ * 	qdisc until the *skb* is freed.
+ *
+ * 	This helper is available only if the kernel was compiled with
+ * 	**CONFIG_IP_ROUTE_CLASSID** configuration option.
+ *
+ * Returns
+ * 	The realm of the route for the packet associated to *skb*, or 0
+ * 	if none was found.
+ */
+static __u32 (*bpf_get_route_realm)(struct __sk_buff *skb) = (void *) 24;
+
+/*
+ * bpf_perf_event_output
+ *
+ * 	Write raw *data* blob into a special BPF perf event held by
+ * 	*map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
+ * 	event must have the following attributes: **PERF_SAMPLE_RAW**
+ * 	as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
+ * 	**PERF_COUNT_SW_BPF_OUTPUT** as **config**.
+ *
+ * 	The *flags* are used to indicate the index in *map* for which
+ * 	the value must be put, masked with **BPF_F_INDEX_MASK**.
+ * 	Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
+ * 	to indicate that the index of the current CPU core should be
+ * 	used.
+ *
+ * 	The value to write, of *size*, is passed through eBPF stack and
+ * 	pointed by *data*.
+ *
+ * 	The context of the program *ctx* needs also be passed to the
+ * 	helper.
+ *
+ * 	On user space, a program willing to read the values needs to
+ * 	call **perf_event_open**\ () on the perf event (either for
+ * 	one or for all CPUs) and to store the file descriptor into the
+ * 	*map*. This must be done before the eBPF program can send data
+ * 	into it. An example is available in file
+ * 	*samples/bpf/trace_output_user.c* in the Linux kernel source
+ * 	tree (the eBPF program counterpart is in
+ * 	*samples/bpf/trace_output_kern.c*).
+ *
+ * 	**bpf_perf_event_output**\ () achieves better performance
+ * 	than **bpf_trace_printk**\ () for sharing data with user
+ * 	space, and is much better suitable for streaming data from eBPF
+ * 	programs.
+ *
+ * 	Note that this helper is not restricted to tracing use cases
+ * 	and can be used with programs attached to TC or XDP as well,
+ * 	where it allows for passing data to user space listeners. Data
+ * 	can be:
+ *
+ * 	* Only custom structs,
+ * 	* Only the packet payload, or
+ * 	* A combination of both.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_perf_event_output)(void *ctx, void *map, __u64 flags, void *data, __u64 size) = (void *) 25;
+
+/*
+ * bpf_skb_load_bytes
+ *
+ * 	This helper was provided as an easy way to load data from a
+ * 	packet. It can be used to load *len* bytes from *offset* from
+ * 	the packet associated to *skb*, into the buffer pointed by
+ * 	*to*.
+ *
+ * 	Since Linux 4.7, usage of this helper has mostly been replaced
+ * 	by "direct packet access", enabling packet data to be
+ * 	manipulated with *skb*\ **->data** and *skb*\ **->data_end**
+ * 	pointing respectively to the first byte of packet data and to
+ * 	the byte after the last byte of packet data. However, it
+ * 	remains useful if one wishes to read large quantities of data
+ * 	at once from a packet into the eBPF stack.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_load_bytes)(const void *skb, __u32 offset, void *to, __u32 len) = (void *) 26;
+
+/*
+ * bpf_get_stackid
+ *
+ * 	Walk a user or a kernel stack and return its id. To achieve
+ * 	this, the helper needs *ctx*, which is a pointer to the context
+ * 	on which the tracing program is executed, and a pointer to a
+ * 	*map* of type **BPF_MAP_TYPE_STACK_TRACE**.
+ *
+ * 	The last argument, *flags*, holds the number of stack frames to
+ * 	skip (from 0 to 255), masked with
+ * 	**BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
+ * 	a combination of the following flags:
+ *
+ * 	**BPF_F_USER_STACK**
+ * 		Collect a user space stack instead of a kernel stack.
+ * 	**BPF_F_FAST_STACK_CMP**
+ * 		Compare stacks by hash only.
+ * 	**BPF_F_REUSE_STACKID**
+ * 		If two different stacks hash into the same *stackid*,
+ * 		discard the old one.
+ *
+ * 	The stack id retrieved is a 32 bit long integer handle which
+ * 	can be further combined with other data (including other stack
+ * 	ids) and used as a key into maps. This can be useful for
+ * 	generating a variety of graphs (such as flame graphs or off-cpu
+ * 	graphs).
+ *
+ * 	For walking a stack, this helper is an improvement over
+ * 	**bpf_probe_read**\ (), which can be used with unrolled loops
+ * 	but is not efficient and consumes a lot of eBPF instructions.
+ * 	Instead, **bpf_get_stackid**\ () can collect up to
+ * 	**PERF_MAX_STACK_DEPTH** both kernel and user frames. Note that
+ * 	this limit can be controlled with the **sysctl** program, and
+ * 	that it should be manually increased in order to profile long
+ * 	user stacks (such as stacks for Java programs). To do so, use:
+ *
+ * 	::
+ *
+ * 		# sysctl kernel.perf_event_max_stack=<new value>
+ *
+ * Returns
+ * 	The positive or null stack id on success, or a negative error
+ * 	in case of failure.
+ */
+static long (*bpf_get_stackid)(void *ctx, void *map, __u64 flags) = (void *) 27;
+
+/*
+ * bpf_csum_diff
+ *
+ * 	Compute a checksum difference, from the raw buffer pointed by
+ * 	*from*, of length *from_size* (that must be a multiple of 4),
+ * 	towards the raw buffer pointed by *to*, of size *to_size*
+ * 	(same remark). An optional *seed* can be added to the value
+ * 	(this can be cascaded, the seed may come from a previous call
+ * 	to the helper).
+ *
+ * 	This is flexible enough to be used in several ways:
+ *
+ * 	* With *from_size* == 0, *to_size* > 0 and *seed* set to
+ * 	  checksum, it can be used when pushing new data.
+ * 	* With *from_size* > 0, *to_size* == 0 and *seed* set to
+ * 	  checksum, it can be used when removing data from a packet.
+ * 	* With *from_size* > 0, *to_size* > 0 and *seed* set to 0, it
+ * 	  can be used to compute a diff. Note that *from_size* and
+ * 	  *to_size* do not need to be equal.
+ *
+ * 	This helper can be used in combination with
+ * 	**bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\ (), to
+ * 	which one can feed in the difference computed with
+ * 	**bpf_csum_diff**\ ().
+ *
+ * Returns
+ * 	The checksum result, or a negative error code in case of
+ * 	failure.
+ */
+static __s64 (*bpf_csum_diff)(__be32 *from, __u32 from_size, __be32 *to, __u32 to_size, __wsum seed) = (void *) 28;
+
+/*
+ * bpf_skb_get_tunnel_opt
+ *
+ * 	Retrieve tunnel options metadata for the packet associated to
+ * 	*skb*, and store the raw tunnel option data to the buffer *opt*
+ * 	of *size*.
+ *
+ * 	This helper can be used with encapsulation devices that can
+ * 	operate in "collect metadata" mode (please refer to the related
+ * 	note in the description of **bpf_skb_get_tunnel_key**\ () for
+ * 	more details). A particular example where this can be used is
+ * 	in combination with the Geneve encapsulation protocol, where it
+ * 	allows for pushing (with **bpf_skb_get_tunnel_opt**\ () helper)
+ * 	and retrieving arbitrary TLVs (Type-Length-Value headers) from
+ * 	the eBPF program. This allows for full customization of these
+ * 	headers.
+ *
+ * Returns
+ * 	The size of the option data retrieved.
+ */
+static long (*bpf_skb_get_tunnel_opt)(struct __sk_buff *skb, void *opt, __u32 size) = (void *) 29;
+
+/*
+ * bpf_skb_set_tunnel_opt
+ *
+ * 	Set tunnel options metadata for the packet associated to *skb*
+ * 	to the option data contained in the raw buffer *opt* of *size*.
+ *
+ * 	See also the description of the **bpf_skb_get_tunnel_opt**\ ()
+ * 	helper for additional information.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_set_tunnel_opt)(struct __sk_buff *skb, void *opt, __u32 size) = (void *) 30;
+
+/*
+ * bpf_skb_change_proto
+ *
+ * 	Change the protocol of the *skb* to *proto*. Currently
+ * 	supported are transition from IPv4 to IPv6, and from IPv6 to
+ * 	IPv4. The helper takes care of the groundwork for the
+ * 	transition, including resizing the socket buffer. The eBPF
+ * 	program is expected to fill the new headers, if any, via
+ * 	**skb_store_bytes**\ () and to recompute the checksums with
+ * 	**bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\
+ * 	(). The main case for this helper is to perform NAT64
+ * 	operations out of an eBPF program.
+ *
+ * 	Internally, the GSO type is marked as dodgy so that headers are
+ * 	checked and segments are recalculated by the GSO/GRO engine.
+ * 	The size for GSO target is adapted as well.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_change_proto)(struct __sk_buff *skb, __be16 proto, __u64 flags) = (void *) 31;
+
+/*
+ * bpf_skb_change_type
+ *
+ * 	Change the packet type for the packet associated to *skb*. This
+ * 	comes down to setting *skb*\ **->pkt_type** to *type*, except
+ * 	the eBPF program does not have a write access to *skb*\
+ * 	**->pkt_type** beside this helper. Using a helper here allows
+ * 	for graceful handling of errors.
+ *
+ * 	The major use case is to change incoming *skb*s to
+ * 	**PACKET_HOST** in a programmatic way instead of having to
+ * 	recirculate via **redirect**\ (..., **BPF_F_INGRESS**), for
+ * 	example.
+ *
+ * 	Note that *type* only allows certain values. At this time, they
+ * 	are:
+ *
+ * 	**PACKET_HOST**
+ * 		Packet is for us.
+ * 	**PACKET_BROADCAST**
+ * 		Send packet to all.
+ * 	**PACKET_MULTICAST**
+ * 		Send packet to group.
+ * 	**PACKET_OTHERHOST**
+ * 		Send packet to someone else.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_change_type)(struct __sk_buff *skb, __u32 type) = (void *) 32;
+
+/*
+ * bpf_skb_under_cgroup
+ *
+ * 	Check whether *skb* is a descendant of the cgroup2 held by
+ * 	*map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
+ *
+ * Returns
+ * 	The return value depends on the result of the test, and can be:
+ *
+ * 	* 0, if the *skb* failed the cgroup2 descendant test.
+ * 	* 1, if the *skb* succeeded the cgroup2 descendant test.
+ * 	* A negative error code, if an error occurred.
+ */
+static long (*bpf_skb_under_cgroup)(struct __sk_buff *skb, void *map, __u32 index) = (void *) 33;
+
+/*
+ * bpf_get_hash_recalc
+ *
+ * 	Retrieve the hash of the packet, *skb*\ **->hash**. If it is
+ * 	not set, in particular if the hash was cleared due to mangling,
+ * 	recompute this hash. Later accesses to the hash can be done
+ * 	directly with *skb*\ **->hash**.
+ *
+ * 	Calling **bpf_set_hash_invalid**\ (), changing a packet
+ * 	prototype with **bpf_skb_change_proto**\ (), or calling
+ * 	**bpf_skb_store_bytes**\ () with the
+ * 	**BPF_F_INVALIDATE_HASH** are actions susceptible to clear
+ * 	the hash and to trigger a new computation for the next call to
+ * 	**bpf_get_hash_recalc**\ ().
+ *
+ * Returns
+ * 	The 32-bit hash.
+ */
+static __u32 (*bpf_get_hash_recalc)(struct __sk_buff *skb) = (void *) 34;
+
+/*
+ * bpf_get_current_task
+ *
+ * 	Get the current task.
+ *
+ * Returns
+ * 	A pointer to the current task struct.
+ */
+static __u64 (*bpf_get_current_task)(void) = (void *) 35;
+
+/*
+ * bpf_probe_write_user
+ *
+ * 	Attempt in a safe way to write *len* bytes from the buffer
+ * 	*src* to *dst* in memory. It only works for threads that are in
+ * 	user context, and *dst* must be a valid user space address.
+ *
+ * 	This helper should not be used to implement any kind of
+ * 	security mechanism because of TOC-TOU attacks, but rather to
+ * 	debug, divert, and manipulate execution of semi-cooperative
+ * 	processes.
+ *
+ * 	Keep in mind that this feature is meant for experiments, and it
+ * 	has a risk of crashing the system and running programs.
+ * 	Therefore, when an eBPF program using this helper is attached,
+ * 	a warning including PID and process name is printed to kernel
+ * 	logs.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_probe_write_user)(void *dst, const void *src, __u32 len) = (void *) 36;
+
+/*
+ * bpf_current_task_under_cgroup
+ *
+ * 	Check whether the probe is being run is the context of a given
+ * 	subset of the cgroup2 hierarchy. The cgroup2 to test is held by
+ * 	*map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
+ *
+ * Returns
+ * 	The return value depends on the result of the test, and can be:
+ *
+ * 	* 1, if current task belongs to the cgroup2.
+ * 	* 0, if current task does not belong to the cgroup2.
+ * 	* A negative error code, if an error occurred.
+ */
+static long (*bpf_current_task_under_cgroup)(void *map, __u32 index) = (void *) 37;
+
+/*
+ * bpf_skb_change_tail
+ *
+ * 	Resize (trim or grow) the packet associated to *skb* to the
+ * 	new *len*. The *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	The basic idea is that the helper performs the needed work to
+ * 	change the size of the packet, then the eBPF program rewrites
+ * 	the rest via helpers like **bpf_skb_store_bytes**\ (),
+ * 	**bpf_l3_csum_replace**\ (), **bpf_l3_csum_replace**\ ()
+ * 	and others. This helper is a slow path utility intended for
+ * 	replies with control messages. And because it is targeted for
+ * 	slow path, the helper itself can afford to be slow: it
+ * 	implicitly linearizes, unclones and drops offloads from the
+ * 	*skb*.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_change_tail)(struct __sk_buff *skb, __u32 len, __u64 flags) = (void *) 38;
+
+/*
+ * bpf_skb_pull_data
+ *
+ * 	Pull in non-linear data in case the *skb* is non-linear and not
+ * 	all of *len* are part of the linear section. Make *len* bytes
+ * 	from *skb* readable and writable. If a zero value is passed for
+ * 	*len*, then all bytes in the linear part of *skb* will be made
+ * 	readable and writable.
+ *
+ * 	This helper is only needed for reading and writing with direct
+ * 	packet access.
+ *
+ * 	For direct packet access, testing that offsets to access
+ * 	are within packet boundaries (test on *skb*\ **->data_end**) is
+ * 	susceptible to fail if offsets are invalid, or if the requested
+ * 	data is in non-linear parts of the *skb*. On failure the
+ * 	program can just bail out, or in the case of a non-linear
+ * 	buffer, use a helper to make the data available. The
+ * 	**bpf_skb_load_bytes**\ () helper is a first solution to access
+ * 	the data. Another one consists in using **bpf_skb_pull_data**
+ * 	to pull in once the non-linear parts, then retesting and
+ * 	eventually access the data.
+ *
+ * 	At the same time, this also makes sure the *skb* is uncloned,
+ * 	which is a necessary condition for direct write. As this needs
+ * 	to be an invariant for the write part only, the verifier
+ * 	detects writes and adds a prologue that is calling
+ * 	**bpf_skb_pull_data()** to effectively unclone the *skb* from
+ * 	the very beginning in case it is indeed cloned.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_pull_data)(struct __sk_buff *skb, __u32 len) = (void *) 39;
+
+/*
+ * bpf_csum_update
+ *
+ * 	Add the checksum *csum* into *skb*\ **->csum** in case the
+ * 	driver has supplied a checksum for the entire packet into that
+ * 	field. Return an error otherwise. This helper is intended to be
+ * 	used in combination with **bpf_csum_diff**\ (), in particular
+ * 	when the checksum needs to be updated after data has been
+ * 	written into the packet through direct packet access.
+ *
+ * Returns
+ * 	The checksum on success, or a negative error code in case of
+ * 	failure.
+ */
+static __s64 (*bpf_csum_update)(struct __sk_buff *skb, __wsum csum) = (void *) 40;
+
+/*
+ * bpf_set_hash_invalid
+ *
+ * 	Invalidate the current *skb*\ **->hash**. It can be used after
+ * 	mangling on headers through direct packet access, in order to
+ * 	indicate that the hash is outdated and to trigger a
+ * 	recalculation the next time the kernel tries to access this
+ * 	hash or when the **bpf_get_hash_recalc**\ () helper is called.
+ *
+ * Returns
+ * 	void.
+ */
+static void (*bpf_set_hash_invalid)(struct __sk_buff *skb) = (void *) 41;
+
+/*
+ * bpf_get_numa_node_id
+ *
+ * 	Return the id of the current NUMA node. The primary use case
+ * 	for this helper is the selection of sockets for the local NUMA
+ * 	node, when the program is attached to sockets using the
+ * 	**SO_ATTACH_REUSEPORT_EBPF** option (see also **socket(7)**),
+ * 	but the helper is also available to other eBPF program types,
+ * 	similarly to **bpf_get_smp_processor_id**\ ().
+ *
+ * Returns
+ * 	The id of current NUMA node.
+ */
+static long (*bpf_get_numa_node_id)(void) = (void *) 42;
+
+/*
+ * bpf_skb_change_head
+ *
+ * 	Grows headroom of packet associated to *skb* and adjusts the
+ * 	offset of the MAC header accordingly, adding *len* bytes of
+ * 	space. It automatically extends and reallocates memory as
+ * 	required.
+ *
+ * 	This helper can be used on a layer 3 *skb* to push a MAC header
+ * 	for redirection into a layer 2 device.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_change_head)(struct __sk_buff *skb, __u32 len, __u64 flags) = (void *) 43;
+
+/*
+ * bpf_xdp_adjust_head
+ *
+ * 	Adjust (move) *xdp_md*\ **->data** by *delta* bytes. Note that
+ * 	it is possible to use a negative value for *delta*. This helper
+ * 	can be used to prepare the packet for pushing or popping
+ * 	headers.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_xdp_adjust_head)(struct xdp_md *xdp_md, int delta) = (void *) 44;
+
+/*
+ * bpf_probe_read_str
+ *
+ * 	Copy a NUL terminated string from an unsafe kernel address
+ * 	*unsafe_ptr* to *dst*. See **bpf_probe_read_kernel_str**\ () for
+ * 	more details.
+ *
+ * 	Generally, use **bpf_probe_read_user_str**\ () or
+ * 	**bpf_probe_read_kernel_str**\ () instead.
+ *
+ * Returns
+ * 	On success, the strictly positive length of the string,
+ * 	including the trailing NUL character. On error, a negative
+ * 	value.
+ */
+static long (*bpf_probe_read_str)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 45;
+
+/*
+ * bpf_get_socket_cookie
+ *
+ * 	If the **struct sk_buff** pointed by *skb* has a known socket,
+ * 	retrieve the cookie (generated by the kernel) of this socket.
+ * 	If no cookie has been set yet, generate a new cookie. Once
+ * 	generated, the socket cookie remains stable for the life of the
+ * 	socket. This helper can be useful for monitoring per socket
+ * 	networking traffic statistics as it provides a global socket
+ * 	identifier that can be assumed unique.
+ *
+ * Returns
+ * 	A 8-byte long unique number on success, or 0 if the socket
+ * 	field is missing inside *skb*.
+ */
+static __u64 (*bpf_get_socket_cookie)(void *ctx) = (void *) 46;
+
+/*
+ * bpf_get_socket_uid
+ *
+ * 	Get the owner UID of the socked associated to *skb*.
+ *
+ * Returns
+ * 	The owner UID of the socket associated to *skb*. If the socket
+ * 	is **NULL**, or if it is not a full socket (i.e. if it is a
+ * 	time-wait or a request socket instead), **overflowuid** value
+ * 	is returned (note that **overflowuid** might also be the actual
+ * 	UID value for the socket).
+ */
+static __u32 (*bpf_get_socket_uid)(struct __sk_buff *skb) = (void *) 47;
+
+/*
+ * bpf_set_hash
+ *
+ * 	Set the full hash for *skb* (set the field *skb*\ **->hash**)
+ * 	to value *hash*.
+ *
+ * Returns
+ * 	0
+ */
+static long (*bpf_set_hash)(struct __sk_buff *skb, __u32 hash) = (void *) 48;
+
+/*
+ * bpf_setsockopt
+ *
+ * 	Emulate a call to **setsockopt()** on the socket associated to
+ * 	*bpf_socket*, which must be a full socket. The *level* at
+ * 	which the option resides and the name *optname* of the option
+ * 	must be specified, see **setsockopt(2)** for more information.
+ * 	The option value of length *optlen* is pointed by *optval*.
+ *
+ * 	*bpf_socket* should be one of the following:
+ *
+ * 	* **struct bpf_sock_ops** for **BPF_PROG_TYPE_SOCK_OPS**.
+ * 	* **struct bpf_sock_addr** for **BPF_CGROUP_INET4_CONNECT**
+ * 	  and **BPF_CGROUP_INET6_CONNECT**.
+ *
+ * 	This helper actually implements a subset of **setsockopt()**.
+ * 	It supports the following *level*\ s:
+ *
+ * 	* **SOL_SOCKET**, which supports the following *optname*\ s:
+ * 	  **SO_RCVBUF**, **SO_SNDBUF**, **SO_MAX_PACING_RATE**,
+ * 	  **SO_PRIORITY**, **SO_RCVLOWAT**, **SO_MARK**,
+ * 	  **SO_BINDTODEVICE**, **SO_KEEPALIVE**, **SO_REUSEADDR**,
+ * 	  **SO_REUSEPORT**, **SO_BINDTOIFINDEX**, **SO_TXREHASH**.
+ * 	* **IPPROTO_TCP**, which supports the following *optname*\ s:
+ * 	  **TCP_CONGESTION**, **TCP_BPF_IW**,
+ * 	  **TCP_BPF_SNDCWND_CLAMP**, **TCP_SAVE_SYN**,
+ * 	  **TCP_KEEPIDLE**, **TCP_KEEPINTVL**, **TCP_KEEPCNT**,
+ * 	  **TCP_SYNCNT**, **TCP_USER_TIMEOUT**, **TCP_NOTSENT_LOWAT**,
+ * 	  **TCP_NODELAY**, **TCP_MAXSEG**, **TCP_WINDOW_CLAMP**,
+ * 	  **TCP_THIN_LINEAR_TIMEOUTS**, **TCP_BPF_DELACK_MAX**,
+ * 	  **TCP_BPF_RTO_MIN**.
+ * 	* **IPPROTO_IP**, which supports *optname* **IP_TOS**.
+ * 	* **IPPROTO_IPV6**, which supports the following *optname*\ s:
+ * 	  **IPV6_TCLASS**, **IPV6_AUTOFLOWLABEL**.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_setsockopt)(void *bpf_socket, int level, int optname, void *optval, int optlen) = (void *) 49;
+
+/*
+ * bpf_skb_adjust_room
+ *
+ * 	Grow or shrink the room for data in the packet associated to
+ * 	*skb* by *len_diff*, and according to the selected *mode*.
+ *
+ * 	By default, the helper will reset any offloaded checksum
+ * 	indicator of the skb to CHECKSUM_NONE. This can be avoided
+ * 	by the following flag:
+ *
+ * 	* **BPF_F_ADJ_ROOM_NO_CSUM_RESET**: Do not reset offloaded
+ * 	  checksum data of the skb to CHECKSUM_NONE.
+ *
+ * 	There are two supported modes at this time:
+ *
+ * 	* **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer
+ * 	  (room space is added or removed between the layer 2 and
+ * 	  layer 3 headers).
+ *
+ * 	* **BPF_ADJ_ROOM_NET**: Adjust room at the network layer
+ * 	  (room space is added or removed between the layer 3 and
+ * 	  layer 4 headers).
+ *
+ * 	The following flags are supported at this time:
+ *
+ * 	* **BPF_F_ADJ_ROOM_FIXED_GSO**: Do not adjust gso_size.
+ * 	  Adjusting mss in this way is not allowed for datagrams.
+ *
+ * 	* **BPF_F_ADJ_ROOM_ENCAP_L3_IPV4**,
+ * 	  **BPF_F_ADJ_ROOM_ENCAP_L3_IPV6**:
+ * 	  Any new space is reserved to hold a tunnel header.
+ * 	  Configure skb offsets and other fields accordingly.
+ *
+ * 	* **BPF_F_ADJ_ROOM_ENCAP_L4_GRE**,
+ * 	  **BPF_F_ADJ_ROOM_ENCAP_L4_UDP**:
+ * 	  Use with ENCAP_L3 flags to further specify the tunnel type.
+ *
+ * 	* **BPF_F_ADJ_ROOM_ENCAP_L2**\ (*len*):
+ * 	  Use with ENCAP_L3/L4 flags to further specify the tunnel
+ * 	  type; *len* is the length of the inner MAC header.
+ *
+ * 	* **BPF_F_ADJ_ROOM_ENCAP_L2_ETH**:
+ * 	  Use with BPF_F_ADJ_ROOM_ENCAP_L2 flag to further specify the
+ * 	  L2 type as Ethernet.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_adjust_room)(struct __sk_buff *skb, __s32 len_diff, __u32 mode, __u64 flags) = (void *) 50;
+
+/*
+ * bpf_redirect_map
+ *
+ * 	Redirect the packet to the endpoint referenced by *map* at
+ * 	index *key*. Depending on its type, this *map* can contain
+ * 	references to net devices (for forwarding packets through other
+ * 	ports), or to CPUs (for redirecting XDP frames to another CPU;
+ * 	but this is only implemented for native XDP (with driver
+ * 	support) as of this writing).
+ *
+ * 	The lower two bits of *flags* are used as the return code if
+ * 	the map lookup fails. This is so that the return value can be
+ * 	one of the XDP program return codes up to **XDP_TX**, as chosen
+ * 	by the caller. The higher bits of *flags* can be set to
+ * 	BPF_F_BROADCAST or BPF_F_EXCLUDE_INGRESS as defined below.
+ *
+ * 	With BPF_F_BROADCAST the packet will be broadcasted to all the
+ * 	interfaces in the map, with BPF_F_EXCLUDE_INGRESS the ingress
+ * 	interface will be excluded when do broadcasting.
+ *
+ * 	See also **bpf_redirect**\ (), which only supports redirecting
+ * 	to an ifindex, but doesn't require a map to do so.
+ *
+ * Returns
+ * 	**XDP_REDIRECT** on success, or the value of the two lower bits
+ * 	of the *flags* argument on error.
+ */
+static long (*bpf_redirect_map)(void *map, __u64 key, __u64 flags) = (void *) 51;
+
+/*
+ * bpf_sk_redirect_map
+ *
+ * 	Redirect the packet to the socket referenced by *map* (of type
+ * 	**BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
+ * 	egress interfaces can be used for redirection. The
+ * 	**BPF_F_INGRESS** value in *flags* is used to make the
+ * 	distinction (ingress path is selected if the flag is present,
+ * 	egress path otherwise). This is the only flag supported for now.
+ *
+ * Returns
+ * 	**SK_PASS** on success, or **SK_DROP** on error.
+ */
+static long (*bpf_sk_redirect_map)(struct __sk_buff *skb, void *map, __u32 key, __u64 flags) = (void *) 52;
+
+/*
+ * bpf_sock_map_update
+ *
+ * 	Add an entry to, or update a *map* referencing sockets. The
+ * 	*skops* is used as a new value for the entry associated to
+ * 	*key*. *flags* is one of:
+ *
+ * 	**BPF_NOEXIST**
+ * 		The entry for *key* must not exist in the map.
+ * 	**BPF_EXIST**
+ * 		The entry for *key* must already exist in the map.
+ * 	**BPF_ANY**
+ * 		No condition on the existence of the entry for *key*.
+ *
+ * 	If the *map* has eBPF programs (parser and verdict), those will
+ * 	be inherited by the socket being added. If the socket is
+ * 	already attached to eBPF programs, this results in an error.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_sock_map_update)(struct bpf_sock_ops *skops, void *map, void *key, __u64 flags) = (void *) 53;
+
+/*
+ * bpf_xdp_adjust_meta
+ *
+ * 	Adjust the address pointed by *xdp_md*\ **->data_meta** by
+ * 	*delta* (which can be positive or negative). Note that this
+ * 	operation modifies the address stored in *xdp_md*\ **->data**,
+ * 	so the latter must be loaded only after the helper has been
+ * 	called.
+ *
+ * 	The use of *xdp_md*\ **->data_meta** is optional and programs
+ * 	are not required to use it. The rationale is that when the
+ * 	packet is processed with XDP (e.g. as DoS filter), it is
+ * 	possible to push further meta data along with it before passing
+ * 	to the stack, and to give the guarantee that an ingress eBPF
+ * 	program attached as a TC classifier on the same device can pick
+ * 	this up for further post-processing. Since TC works with socket
+ * 	buffers, it remains possible to set from XDP the **mark** or
+ * 	**priority** pointers, or other pointers for the socket buffer.
+ * 	Having this scratch space generic and programmable allows for
+ * 	more flexibility as the user is free to store whatever meta
+ * 	data they need.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_xdp_adjust_meta)(struct xdp_md *xdp_md, int delta) = (void *) 54;
+
+/*
+ * bpf_perf_event_read_value
+ *
+ * 	Read the value of a perf event counter, and store it into *buf*
+ * 	of size *buf_size*. This helper relies on a *map* of type
+ * 	**BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of the perf event
+ * 	counter is selected when *map* is updated with perf event file
+ * 	descriptors. The *map* is an array whose size is the number of
+ * 	available CPUs, and each cell contains a value relative to one
+ * 	CPU. The value to retrieve is indicated by *flags*, that
+ * 	contains the index of the CPU to look up, masked with
+ * 	**BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
+ * 	**BPF_F_CURRENT_CPU** to indicate that the value for the
+ * 	current CPU should be retrieved.
+ *
+ * 	This helper behaves in a way close to
+ * 	**bpf_perf_event_read**\ () helper, save that instead of
+ * 	just returning the value observed, it fills the *buf*
+ * 	structure. This allows for additional data to be retrieved: in
+ * 	particular, the enabled and running times (in *buf*\
+ * 	**->enabled** and *buf*\ **->running**, respectively) are
+ * 	copied. In general, **bpf_perf_event_read_value**\ () is
+ * 	recommended over **bpf_perf_event_read**\ (), which has some
+ * 	ABI issues and provides fewer functionalities.
+ *
+ * 	These values are interesting, because hardware PMU (Performance
+ * 	Monitoring Unit) counters are limited resources. When there are
+ * 	more PMU based perf events opened than available counters,
+ * 	kernel will multiplex these events so each event gets certain
+ * 	percentage (but not all) of the PMU time. In case that
+ * 	multiplexing happens, the number of samples or counter value
+ * 	will not reflect the case compared to when no multiplexing
+ * 	occurs. This makes comparison between different runs difficult.
+ * 	Typically, the counter value should be normalized before
+ * 	comparing to other experiments. The usual normalization is done
+ * 	as follows.
+ *
+ * 	::
+ *
+ * 		normalized_counter = counter * t_enabled / t_running
+ *
+ * 	Where t_enabled is the time enabled for event and t_running is
+ * 	the time running for event since last normalization. The
+ * 	enabled and running times are accumulated since the perf event
+ * 	open. To achieve scaling factor between two invocations of an
+ * 	eBPF program, users can use CPU id as the key (which is
+ * 	typical for perf array usage model) to remember the previous
+ * 	value and do the calculation inside the eBPF program.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_perf_event_read_value)(void *map, __u64 flags, struct bpf_perf_event_value *buf, __u32 buf_size) = (void *) 55;
+
+/*
+ * bpf_perf_prog_read_value
+ *
+ * 	For en eBPF program attached to a perf event, retrieve the
+ * 	value of the event counter associated to *ctx* and store it in
+ * 	the structure pointed by *buf* and of size *buf_size*. Enabled
+ * 	and running times are also stored in the structure (see
+ * 	description of helper **bpf_perf_event_read_value**\ () for
+ * 	more details).
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_perf_prog_read_value)(struct bpf_perf_event_data *ctx, struct bpf_perf_event_value *buf, __u32 buf_size) = (void *) 56;
+
+/*
+ * bpf_getsockopt
+ *
+ * 	Emulate a call to **getsockopt()** on the socket associated to
+ * 	*bpf_socket*, which must be a full socket. The *level* at
+ * 	which the option resides and the name *optname* of the option
+ * 	must be specified, see **getsockopt(2)** for more information.
+ * 	The retrieved value is stored in the structure pointed by
+ * 	*opval* and of length *optlen*.
+ *
+ * 	*bpf_socket* should be one of the following:
+ *
+ * 	* **struct bpf_sock_ops** for **BPF_PROG_TYPE_SOCK_OPS**.
+ * 	* **struct bpf_sock_addr** for **BPF_CGROUP_INET4_CONNECT**
+ * 	  and **BPF_CGROUP_INET6_CONNECT**.
+ *
+ * 	This helper actually implements a subset of **getsockopt()**.
+ * 	It supports the same set of *optname*\ s that is supported by
+ * 	the **bpf_setsockopt**\ () helper.  The exceptions are
+ * 	**TCP_BPF_*** is **bpf_setsockopt**\ () only and
+ * 	**TCP_SAVED_SYN** is **bpf_getsockopt**\ () only.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_getsockopt)(void *bpf_socket, int level, int optname, void *optval, int optlen) = (void *) 57;
+
+/*
+ * bpf_override_return
+ *
+ * 	Used for error injection, this helper uses kprobes to override
+ * 	the return value of the probed function, and to set it to *rc*.
+ * 	The first argument is the context *regs* on which the kprobe
+ * 	works.
+ *
+ * 	This helper works by setting the PC (program counter)
+ * 	to an override function which is run in place of the original
+ * 	probed function. This means the probed function is not run at
+ * 	all. The replacement function just returns with the required
+ * 	value.
+ *
+ * 	This helper has security implications, and thus is subject to
+ * 	restrictions. It is only available if the kernel was compiled
+ * 	with the **CONFIG_BPF_KPROBE_OVERRIDE** configuration
+ * 	option, and in this case it only works on functions tagged with
+ * 	**ALLOW_ERROR_INJECTION** in the kernel code.
+ *
+ * 	Also, the helper is only available for the architectures having
+ * 	the CONFIG_FUNCTION_ERROR_INJECTION option. As of this writing,
+ * 	x86 architecture is the only one to support this feature.
+ *
+ * Returns
+ * 	0
+ */
+static long (*bpf_override_return)(struct pt_regs *regs, __u64 rc) = (void *) 58;
+
+/*
+ * bpf_sock_ops_cb_flags_set
+ *
+ * 	Attempt to set the value of the **bpf_sock_ops_cb_flags** field
+ * 	for the full TCP socket associated to *bpf_sock_ops* to
+ * 	*argval*.
+ *
+ * 	The primary use of this field is to determine if there should
+ * 	be calls to eBPF programs of type
+ * 	**BPF_PROG_TYPE_SOCK_OPS** at various points in the TCP
+ * 	code. A program of the same type can change its value, per
+ * 	connection and as necessary, when the connection is
+ * 	established. This field is directly accessible for reading, but
+ * 	this helper must be used for updates in order to return an
+ * 	error if an eBPF program tries to set a callback that is not
+ * 	supported in the current kernel.
+ *
+ * 	*argval* is a flag array which can combine these flags:
+ *
+ * 	* **BPF_SOCK_OPS_RTO_CB_FLAG** (retransmission time out)
+ * 	* **BPF_SOCK_OPS_RETRANS_CB_FLAG** (retransmission)
+ * 	* **BPF_SOCK_OPS_STATE_CB_FLAG** (TCP state change)
+ * 	* **BPF_SOCK_OPS_RTT_CB_FLAG** (every RTT)
+ *
+ * 	Therefore, this function can be used to clear a callback flag by
+ * 	setting the appropriate bit to zero. e.g. to disable the RTO
+ * 	callback:
+ *
+ * 	**bpf_sock_ops_cb_flags_set(bpf_sock,**
+ * 		**bpf_sock->bpf_sock_ops_cb_flags & ~BPF_SOCK_OPS_RTO_CB_FLAG)**
+ *
+ * 	Here are some examples of where one could call such eBPF
+ * 	program:
+ *
+ * 	* When RTO fires.
+ * 	* When a packet is retransmitted.
+ * 	* When the connection terminates.
+ * 	* When a packet is sent.
+ * 	* When a packet is received.
+ *
+ * Returns
+ * 	Code **-EINVAL** if the socket is not a full TCP socket;
+ * 	otherwise, a positive number containing the bits that could not
+ * 	be set is returned (which comes down to 0 if all bits were set
+ * 	as required).
+ */
+static long (*bpf_sock_ops_cb_flags_set)(struct bpf_sock_ops *bpf_sock, int argval) = (void *) 59;
+
+/*
+ * bpf_msg_redirect_map
+ *
+ * 	This helper is used in programs implementing policies at the
+ * 	socket level. If the message *msg* is allowed to pass (i.e. if
+ * 	the verdict eBPF program returns **SK_PASS**), redirect it to
+ * 	the socket referenced by *map* (of type
+ * 	**BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
+ * 	egress interfaces can be used for redirection. The
+ * 	**BPF_F_INGRESS** value in *flags* is used to make the
+ * 	distinction (ingress path is selected if the flag is present,
+ * 	egress path otherwise). This is the only flag supported for now.
+ *
+ * Returns
+ * 	**SK_PASS** on success, or **SK_DROP** on error.
+ */
+static long (*bpf_msg_redirect_map)(struct sk_msg_md *msg, void *map, __u32 key, __u64 flags) = (void *) 60;
+
+/*
+ * bpf_msg_apply_bytes
+ *
+ * 	For socket policies, apply the verdict of the eBPF program to
+ * 	the next *bytes* (number of bytes) of message *msg*.
+ *
+ * 	For example, this helper can be used in the following cases:
+ *
+ * 	* A single **sendmsg**\ () or **sendfile**\ () system call
+ * 	  contains multiple logical messages that the eBPF program is
+ * 	  supposed to read and for which it should apply a verdict.
+ * 	* An eBPF program only cares to read the first *bytes* of a
+ * 	  *msg*. If the message has a large payload, then setting up
+ * 	  and calling the eBPF program repeatedly for all bytes, even
+ * 	  though the verdict is already known, would create unnecessary
+ * 	  overhead.
+ *
+ * 	When called from within an eBPF program, the helper sets a
+ * 	counter internal to the BPF infrastructure, that is used to
+ * 	apply the last verdict to the next *bytes*. If *bytes* is
+ * 	smaller than the current data being processed from a
+ * 	**sendmsg**\ () or **sendfile**\ () system call, the first
+ * 	*bytes* will be sent and the eBPF program will be re-run with
+ * 	the pointer for start of data pointing to byte number *bytes*
+ * 	**+ 1**. If *bytes* is larger than the current data being
+ * 	processed, then the eBPF verdict will be applied to multiple
+ * 	**sendmsg**\ () or **sendfile**\ () calls until *bytes* are
+ * 	consumed.
+ *
+ * 	Note that if a socket closes with the internal counter holding
+ * 	a non-zero value, this is not a problem because data is not
+ * 	being buffered for *bytes* and is sent as it is received.
+ *
+ * Returns
+ * 	0
+ */
+static long (*bpf_msg_apply_bytes)(struct sk_msg_md *msg, __u32 bytes) = (void *) 61;
+
+/*
+ * bpf_msg_cork_bytes
+ *
+ * 	For socket policies, prevent the execution of the verdict eBPF
+ * 	program for message *msg* until *bytes* (byte number) have been
+ * 	accumulated.
+ *
+ * 	This can be used when one needs a specific number of bytes
+ * 	before a verdict can be assigned, even if the data spans
+ * 	multiple **sendmsg**\ () or **sendfile**\ () calls. The extreme
+ * 	case would be a user calling **sendmsg**\ () repeatedly with
+ * 	1-byte long message segments. Obviously, this is bad for
+ * 	performance, but it is still valid. If the eBPF program needs
+ * 	*bytes* bytes to validate a header, this helper can be used to
+ * 	prevent the eBPF program to be called again until *bytes* have
+ * 	been accumulated.
+ *
+ * Returns
+ * 	0
+ */
+static long (*bpf_msg_cork_bytes)(struct sk_msg_md *msg, __u32 bytes) = (void *) 62;
+
+/*
+ * bpf_msg_pull_data
+ *
+ * 	For socket policies, pull in non-linear data from user space
+ * 	for *msg* and set pointers *msg*\ **->data** and *msg*\
+ * 	**->data_end** to *start* and *end* bytes offsets into *msg*,
+ * 	respectively.
+ *
+ * 	If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
+ * 	*msg* it can only parse data that the (**data**, **data_end**)
+ * 	pointers have already consumed. For **sendmsg**\ () hooks this
+ * 	is likely the first scatterlist element. But for calls relying
+ * 	on the **sendpage** handler (e.g. **sendfile**\ ()) this will
+ * 	be the range (**0**, **0**) because the data is shared with
+ * 	user space and by default the objective is to avoid allowing
+ * 	user space to modify data while (or after) eBPF verdict is
+ * 	being decided. This helper can be used to pull in data and to
+ * 	set the start and end pointer to given values. Data will be
+ * 	copied if necessary (i.e. if data was not linear and if start
+ * 	and end pointers do not point to the same chunk).
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_msg_pull_data)(struct sk_msg_md *msg, __u32 start, __u32 end, __u64 flags) = (void *) 63;
+
+/*
+ * bpf_bind
+ *
+ * 	Bind the socket associated to *ctx* to the address pointed by
+ * 	*addr*, of length *addr_len*. This allows for making outgoing
+ * 	connection from the desired IP address, which can be useful for
+ * 	example when all processes inside a cgroup should use one
+ * 	single IP address on a host that has multiple IP configured.
+ *
+ * 	This helper works for IPv4 and IPv6, TCP and UDP sockets. The
+ * 	domain (*addr*\ **->sa_family**) must be **AF_INET** (or
+ * 	**AF_INET6**). It's advised to pass zero port (**sin_port**
+ * 	or **sin6_port**) which triggers IP_BIND_ADDRESS_NO_PORT-like
+ * 	behavior and lets the kernel efficiently pick up an unused
+ * 	port as long as 4-tuple is unique. Passing non-zero port might
+ * 	lead to degraded performance.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_bind)(struct bpf_sock_addr *ctx, struct sockaddr *addr, int addr_len) = (void *) 64;
+
+/*
+ * bpf_xdp_adjust_tail
+ *
+ * 	Adjust (move) *xdp_md*\ **->data_end** by *delta* bytes. It is
+ * 	possible to both shrink and grow the packet tail.
+ * 	Shrink done via *delta* being a negative integer.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_xdp_adjust_tail)(struct xdp_md *xdp_md, int delta) = (void *) 65;
+
+/*
+ * bpf_skb_get_xfrm_state
+ *
+ * 	Retrieve the XFRM state (IP transform framework, see also
+ * 	**ip-xfrm(8)**) at *index* in XFRM "security path" for *skb*.
+ *
+ * 	The retrieved value is stored in the **struct bpf_xfrm_state**
+ * 	pointed by *xfrm_state* and of length *size*.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	This helper is available only if the kernel was compiled with
+ * 	**CONFIG_XFRM** configuration option.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_get_xfrm_state)(struct __sk_buff *skb, __u32 index, struct bpf_xfrm_state *xfrm_state, __u32 size, __u64 flags) = (void *) 66;
+
+/*
+ * bpf_get_stack
+ *
+ * 	Return a user or a kernel stack in bpf program provided buffer.
+ * 	To achieve this, the helper needs *ctx*, which is a pointer
+ * 	to the context on which the tracing program is executed.
+ * 	To store the stacktrace, the bpf program provides *buf* with
+ * 	a nonnegative *size*.
+ *
+ * 	The last argument, *flags*, holds the number of stack frames to
+ * 	skip (from 0 to 255), masked with
+ * 	**BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
+ * 	the following flags:
+ *
+ * 	**BPF_F_USER_STACK**
+ * 		Collect a user space stack instead of a kernel stack.
+ * 	**BPF_F_USER_BUILD_ID**
+ * 		Collect (build_id, file_offset) instead of ips for user
+ * 		stack, only valid if **BPF_F_USER_STACK** is also
+ * 		specified.
+ *
+ * 		*file_offset* is an offset relative to the beginning
+ * 		of the executable or shared object file backing the vma
+ * 		which the *ip* falls in. It is *not* an offset relative
+ * 		to that object's base address. Accordingly, it must be
+ * 		adjusted by adding (sh_addr - sh_offset), where
+ * 		sh_{addr,offset} correspond to the executable section
+ * 		containing *file_offset* in the object, for comparisons
+ * 		to symbols' st_value to be valid.
+ *
+ * 	**bpf_get_stack**\ () can collect up to
+ * 	**PERF_MAX_STACK_DEPTH** both kernel and user frames, subject
+ * 	to sufficient large buffer size. Note that
+ * 	this limit can be controlled with the **sysctl** program, and
+ * 	that it should be manually increased in order to profile long
+ * 	user stacks (such as stacks for Java programs). To do so, use:
+ *
+ * 	::
+ *
+ * 		# sysctl kernel.perf_event_max_stack=<new value>
+ *
+ * Returns
+ * 	The non-negative copied *buf* length equal to or less than
+ * 	*size* on success, or a negative error in case of failure.
+ */
+static long (*bpf_get_stack)(void *ctx, void *buf, __u32 size, __u64 flags) = (void *) 67;
+
+/*
+ * bpf_skb_load_bytes_relative
+ *
+ * 	This helper is similar to **bpf_skb_load_bytes**\ () in that
+ * 	it provides an easy way to load *len* bytes from *offset*
+ * 	from the packet associated to *skb*, into the buffer pointed
+ * 	by *to*. The difference to **bpf_skb_load_bytes**\ () is that
+ * 	a fifth argument *start_header* exists in order to select a
+ * 	base offset to start from. *start_header* can be one of:
+ *
+ * 	**BPF_HDR_START_MAC**
+ * 		Base offset to load data from is *skb*'s mac header.
+ * 	**BPF_HDR_START_NET**
+ * 		Base offset to load data from is *skb*'s network header.
+ *
+ * 	In general, "direct packet access" is the preferred method to
+ * 	access packet data, however, this helper is in particular useful
+ * 	in socket filters where *skb*\ **->data** does not always point
+ * 	to the start of the mac header and where "direct packet access"
+ * 	is not available.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_load_bytes_relative)(const void *skb, __u32 offset, void *to, __u32 len, __u32 start_header) = (void *) 68;
+
+/*
+ * bpf_fib_lookup
+ *
+ * 	Do FIB lookup in kernel tables using parameters in *params*.
+ * 	If lookup is successful and result shows packet is to be
+ * 	forwarded, the neighbor tables are searched for the nexthop.
+ * 	If successful (ie., FIB lookup shows forwarding and nexthop
+ * 	is resolved), the nexthop address is returned in ipv4_dst
+ * 	or ipv6_dst based on family, smac is set to mac address of
+ * 	egress device, dmac is set to nexthop mac address, rt_metric
+ * 	is set to metric from route (IPv4/IPv6 only), and ifindex
+ * 	is set to the device index of the nexthop from the FIB lookup.
+ *
+ * 	*plen* argument is the size of the passed in struct.
+ * 	*flags* argument can be a combination of one or more of the
+ * 	following values:
+ *
+ * 	**BPF_FIB_LOOKUP_DIRECT**
+ * 		Do a direct table lookup vs full lookup using FIB
+ * 		rules.
+ * 	**BPF_FIB_LOOKUP_OUTPUT**
+ * 		Perform lookup from an egress perspective (default is
+ * 		ingress).
+ *
+ * 	*ctx* is either **struct xdp_md** for XDP programs or
+ * 	**struct sk_buff** tc cls_act programs.
+ *
+ * Returns
+ * 	* < 0 if any input argument is invalid
+ * 	*   0 on success (packet is forwarded, nexthop neighbor exists)
+ * 	* > 0 one of **BPF_FIB_LKUP_RET_** codes explaining why the
+ * 	  packet is not forwarded or needs assist from full stack
+ *
+ * 	If lookup fails with BPF_FIB_LKUP_RET_FRAG_NEEDED, then the MTU
+ * 	was exceeded and output params->mtu_result contains the MTU.
+ */
+static long (*bpf_fib_lookup)(void *ctx, struct bpf_fib_lookup *params, int plen, __u32 flags) = (void *) 69;
+
+/*
+ * bpf_sock_hash_update
+ *
+ * 	Add an entry to, or update a sockhash *map* referencing sockets.
+ * 	The *skops* is used as a new value for the entry associated to
+ * 	*key*. *flags* is one of:
+ *
+ * 	**BPF_NOEXIST**
+ * 		The entry for *key* must not exist in the map.
+ * 	**BPF_EXIST**
+ * 		The entry for *key* must already exist in the map.
+ * 	**BPF_ANY**
+ * 		No condition on the existence of the entry for *key*.
+ *
+ * 	If the *map* has eBPF programs (parser and verdict), those will
+ * 	be inherited by the socket being added. If the socket is
+ * 	already attached to eBPF programs, this results in an error.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_sock_hash_update)(struct bpf_sock_ops *skops, void *map, void *key, __u64 flags) = (void *) 70;
+
+/*
+ * bpf_msg_redirect_hash
+ *
+ * 	This helper is used in programs implementing policies at the
+ * 	socket level. If the message *msg* is allowed to pass (i.e. if
+ * 	the verdict eBPF program returns **SK_PASS**), redirect it to
+ * 	the socket referenced by *map* (of type
+ * 	**BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
+ * 	egress interfaces can be used for redirection. The
+ * 	**BPF_F_INGRESS** value in *flags* is used to make the
+ * 	distinction (ingress path is selected if the flag is present,
+ * 	egress path otherwise). This is the only flag supported for now.
+ *
+ * Returns
+ * 	**SK_PASS** on success, or **SK_DROP** on error.
+ */
+static long (*bpf_msg_redirect_hash)(struct sk_msg_md *msg, void *map, void *key, __u64 flags) = (void *) 71;
+
+/*
+ * bpf_sk_redirect_hash
+ *
+ * 	This helper is used in programs implementing policies at the
+ * 	skb socket level. If the sk_buff *skb* is allowed to pass (i.e.
+ * 	if the verdict eBPF program returns **SK_PASS**), redirect it
+ * 	to the socket referenced by *map* (of type
+ * 	**BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
+ * 	egress interfaces can be used for redirection. The
+ * 	**BPF_F_INGRESS** value in *flags* is used to make the
+ * 	distinction (ingress path is selected if the flag is present,
+ * 	egress otherwise). This is the only flag supported for now.
+ *
+ * Returns
+ * 	**SK_PASS** on success, or **SK_DROP** on error.
+ */
+static long (*bpf_sk_redirect_hash)(struct __sk_buff *skb, void *map, void *key, __u64 flags) = (void *) 72;
+
+/*
+ * bpf_lwt_push_encap
+ *
+ * 	Encapsulate the packet associated to *skb* within a Layer 3
+ * 	protocol header. This header is provided in the buffer at
+ * 	address *hdr*, with *len* its size in bytes. *type* indicates
+ * 	the protocol of the header and can be one of:
+ *
+ * 	**BPF_LWT_ENCAP_SEG6**
+ * 		IPv6 encapsulation with Segment Routing Header
+ * 		(**struct ipv6_sr_hdr**). *hdr* only contains the SRH,
+ * 		the IPv6 header is computed by the kernel.
+ * 	**BPF_LWT_ENCAP_SEG6_INLINE**
+ * 		Only works if *skb* contains an IPv6 packet. Insert a
+ * 		Segment Routing Header (**struct ipv6_sr_hdr**) inside
+ * 		the IPv6 header.
+ * 	**BPF_LWT_ENCAP_IP**
+ * 		IP encapsulation (GRE/GUE/IPIP/etc). The outer header
+ * 		must be IPv4 or IPv6, followed by zero or more
+ * 		additional headers, up to **LWT_BPF_MAX_HEADROOM**
+ * 		total bytes in all prepended headers. Please note that
+ * 		if **skb_is_gso**\ (*skb*) is true, no more than two
+ * 		headers can be prepended, and the inner header, if
+ * 		present, should be either GRE or UDP/GUE.
+ *
+ * 	**BPF_LWT_ENCAP_SEG6**\ \* types can be called by BPF programs
+ * 	of type **BPF_PROG_TYPE_LWT_IN**; **BPF_LWT_ENCAP_IP** type can
+ * 	be called by bpf programs of types **BPF_PROG_TYPE_LWT_IN** and
+ * 	**BPF_PROG_TYPE_LWT_XMIT**.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_lwt_push_encap)(struct __sk_buff *skb, __u32 type, void *hdr, __u32 len) = (void *) 73;
+
+/*
+ * bpf_lwt_seg6_store_bytes
+ *
+ * 	Store *len* bytes from address *from* into the packet
+ * 	associated to *skb*, at *offset*. Only the flags, tag and TLVs
+ * 	inside the outermost IPv6 Segment Routing Header can be
+ * 	modified through this helper.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_lwt_seg6_store_bytes)(struct __sk_buff *skb, __u32 offset, const void *from, __u32 len) = (void *) 74;
+
+/*
+ * bpf_lwt_seg6_adjust_srh
+ *
+ * 	Adjust the size allocated to TLVs in the outermost IPv6
+ * 	Segment Routing Header contained in the packet associated to
+ * 	*skb*, at position *offset* by *delta* bytes. Only offsets
+ * 	after the segments are accepted. *delta* can be as well
+ * 	positive (growing) as negative (shrinking).
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_lwt_seg6_adjust_srh)(struct __sk_buff *skb, __u32 offset, __s32 delta) = (void *) 75;
+
+/*
+ * bpf_lwt_seg6_action
+ *
+ * 	Apply an IPv6 Segment Routing action of type *action* to the
+ * 	packet associated to *skb*. Each action takes a parameter
+ * 	contained at address *param*, and of length *param_len* bytes.
+ * 	*action* can be one of:
+ *
+ * 	**SEG6_LOCAL_ACTION_END_X**
+ * 		End.X action: Endpoint with Layer-3 cross-connect.
+ * 		Type of *param*: **struct in6_addr**.
+ * 	**SEG6_LOCAL_ACTION_END_T**
+ * 		End.T action: Endpoint with specific IPv6 table lookup.
+ * 		Type of *param*: **int**.
+ * 	**SEG6_LOCAL_ACTION_END_B6**
+ * 		End.B6 action: Endpoint bound to an SRv6 policy.
+ * 		Type of *param*: **struct ipv6_sr_hdr**.
+ * 	**SEG6_LOCAL_ACTION_END_B6_ENCAP**
+ * 		End.B6.Encap action: Endpoint bound to an SRv6
+ * 		encapsulation policy.
+ * 		Type of *param*: **struct ipv6_sr_hdr**.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_lwt_seg6_action)(struct __sk_buff *skb, __u32 action, void *param, __u32 param_len) = (void *) 76;
+
+/*
+ * bpf_rc_repeat
+ *
+ * 	This helper is used in programs implementing IR decoding, to
+ * 	report a successfully decoded repeat key message. This delays
+ * 	the generation of a key up event for previously generated
+ * 	key down event.
+ *
+ * 	Some IR protocols like NEC have a special IR message for
+ * 	repeating last button, for when a button is held down.
+ *
+ * 	The *ctx* should point to the lirc sample as passed into
+ * 	the program.
+ *
+ * 	This helper is only available is the kernel was compiled with
+ * 	the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ * 	"**y**".
+ *
+ * Returns
+ * 	0
+ */
+static long (*bpf_rc_repeat)(void *ctx) = (void *) 77;
+
+/*
+ * bpf_rc_keydown
+ *
+ * 	This helper is used in programs implementing IR decoding, to
+ * 	report a successfully decoded key press with *scancode*,
+ * 	*toggle* value in the given *protocol*. The scancode will be
+ * 	translated to a keycode using the rc keymap, and reported as
+ * 	an input key down event. After a period a key up event is
+ * 	generated. This period can be extended by calling either
+ * 	**bpf_rc_keydown**\ () again with the same values, or calling
+ * 	**bpf_rc_repeat**\ ().
+ *
+ * 	Some protocols include a toggle bit, in case the button was
+ * 	released and pressed again between consecutive scancodes.
+ *
+ * 	The *ctx* should point to the lirc sample as passed into
+ * 	the program.
+ *
+ * 	The *protocol* is the decoded protocol number (see
+ * 	**enum rc_proto** for some predefined values).
+ *
+ * 	This helper is only available is the kernel was compiled with
+ * 	the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ * 	"**y**".
+ *
+ * Returns
+ * 	0
+ */
+static long (*bpf_rc_keydown)(void *ctx, __u32 protocol, __u64 scancode, __u32 toggle) = (void *) 78;
+
+/*
+ * bpf_skb_cgroup_id
+ *
+ * 	Return the cgroup v2 id of the socket associated with the *skb*.
+ * 	This is roughly similar to the **bpf_get_cgroup_classid**\ ()
+ * 	helper for cgroup v1 by providing a tag resp. identifier that
+ * 	can be matched on or used for map lookups e.g. to implement
+ * 	policy. The cgroup v2 id of a given path in the hierarchy is
+ * 	exposed in user space through the f_handle API in order to get
+ * 	to the same 64-bit id.
+ *
+ * 	This helper can be used on TC egress path, but not on ingress,
+ * 	and is available only if the kernel was compiled with the
+ * 	**CONFIG_SOCK_CGROUP_DATA** configuration option.
+ *
+ * Returns
+ * 	The id is returned or 0 in case the id could not be retrieved.
+ */
+static __u64 (*bpf_skb_cgroup_id)(struct __sk_buff *skb) = (void *) 79;
+
+/*
+ * bpf_get_current_cgroup_id
+ *
+ * 	Get the current cgroup id based on the cgroup within which
+ * 	the current task is running.
+ *
+ * Returns
+ * 	A 64-bit integer containing the current cgroup id based
+ * 	on the cgroup within which the current task is running.
+ */
+static __u64 (*bpf_get_current_cgroup_id)(void) = (void *) 80;
+
+/*
+ * bpf_get_local_storage
+ *
+ * 	Get the pointer to the local storage area.
+ * 	The type and the size of the local storage is defined
+ * 	by the *map* argument.
+ * 	The *flags* meaning is specific for each map type,
+ * 	and has to be 0 for cgroup local storage.
+ *
+ * 	Depending on the BPF program type, a local storage area
+ * 	can be shared between multiple instances of the BPF program,
+ * 	running simultaneously.
+ *
+ * 	A user should care about the synchronization by himself.
+ * 	For example, by using the **BPF_ATOMIC** instructions to alter
+ * 	the shared data.
+ *
+ * Returns
+ * 	A pointer to the local storage area.
+ */
+static void *(*bpf_get_local_storage)(void *map, __u64 flags) = (void *) 81;
+
+/*
+ * bpf_sk_select_reuseport
+ *
+ * 	Select a **SO_REUSEPORT** socket from a
+ * 	**BPF_MAP_TYPE_REUSEPORT_SOCKARRAY** *map*.
+ * 	It checks the selected socket is matching the incoming
+ * 	request in the socket buffer.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_sk_select_reuseport)(struct sk_reuseport_md *reuse, void *map, void *key, __u64 flags) = (void *) 82;
+
+/*
+ * bpf_skb_ancestor_cgroup_id
+ *
+ * 	Return id of cgroup v2 that is ancestor of cgroup associated
+ * 	with the *skb* at the *ancestor_level*.  The root cgroup is at
+ * 	*ancestor_level* zero and each step down the hierarchy
+ * 	increments the level. If *ancestor_level* == level of cgroup
+ * 	associated with *skb*, then return value will be same as that
+ * 	of **bpf_skb_cgroup_id**\ ().
+ *
+ * 	The helper is useful to implement policies based on cgroups
+ * 	that are upper in hierarchy than immediate cgroup associated
+ * 	with *skb*.
+ *
+ * 	The format of returned id and helper limitations are same as in
+ * 	**bpf_skb_cgroup_id**\ ().
+ *
+ * Returns
+ * 	The id is returned or 0 in case the id could not be retrieved.
+ */
+static __u64 (*bpf_skb_ancestor_cgroup_id)(struct __sk_buff *skb, int ancestor_level) = (void *) 83;
+
+/*
+ * bpf_sk_lookup_tcp
+ *
+ * 	Look for TCP socket matching *tuple*, optionally in a child
+ * 	network namespace *netns*. The return value must be checked,
+ * 	and if non-**NULL**, released via **bpf_sk_release**\ ().
+ *
+ * 	The *ctx* should point to the context of the program, such as
+ * 	the skb or socket (depending on the hook in use). This is used
+ * 	to determine the base network namespace for the lookup.
+ *
+ * 	*tuple_size* must be one of:
+ *
+ * 	**sizeof**\ (*tuple*\ **->ipv4**)
+ * 		Look for an IPv4 socket.
+ * 	**sizeof**\ (*tuple*\ **->ipv6**)
+ * 		Look for an IPv6 socket.
+ *
+ * 	If the *netns* is a negative signed 32-bit integer, then the
+ * 	socket lookup table in the netns associated with the *ctx*
+ * 	will be used. For the TC hooks, this is the netns of the device
+ * 	in the skb. For socket hooks, this is the netns of the socket.
+ * 	If *netns* is any other signed 32-bit value greater than or
+ * 	equal to zero then it specifies the ID of the netns relative to
+ * 	the netns associated with the *ctx*. *netns* values beyond the
+ * 	range of 32-bit integers are reserved for future use.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	This helper is available only if the kernel was compiled with
+ * 	**CONFIG_NET** configuration option.
+ *
+ * Returns
+ * 	Pointer to **struct bpf_sock**, or **NULL** in case of failure.
+ * 	For sockets with reuseport option, the **struct bpf_sock**
+ * 	result is from *reuse*\ **->socks**\ [] using the hash of the
+ * 	tuple.
+ */
+static struct bpf_sock *(*bpf_sk_lookup_tcp)(void *ctx, struct bpf_sock_tuple *tuple, __u32 tuple_size, __u64 netns, __u64 flags) = (void *) 84;
+
+/*
+ * bpf_sk_lookup_udp
+ *
+ * 	Look for UDP socket matching *tuple*, optionally in a child
+ * 	network namespace *netns*. The return value must be checked,
+ * 	and if non-**NULL**, released via **bpf_sk_release**\ ().
+ *
+ * 	The *ctx* should point to the context of the program, such as
+ * 	the skb or socket (depending on the hook in use). This is used
+ * 	to determine the base network namespace for the lookup.
+ *
+ * 	*tuple_size* must be one of:
+ *
+ * 	**sizeof**\ (*tuple*\ **->ipv4**)
+ * 		Look for an IPv4 socket.
+ * 	**sizeof**\ (*tuple*\ **->ipv6**)
+ * 		Look for an IPv6 socket.
+ *
+ * 	If the *netns* is a negative signed 32-bit integer, then the
+ * 	socket lookup table in the netns associated with the *ctx*
+ * 	will be used. For the TC hooks, this is the netns of the device
+ * 	in the skb. For socket hooks, this is the netns of the socket.
+ * 	If *netns* is any other signed 32-bit value greater than or
+ * 	equal to zero then it specifies the ID of the netns relative to
+ * 	the netns associated with the *ctx*. *netns* values beyond the
+ * 	range of 32-bit integers are reserved for future use.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	This helper is available only if the kernel was compiled with
+ * 	**CONFIG_NET** configuration option.
+ *
+ * Returns
+ * 	Pointer to **struct bpf_sock**, or **NULL** in case of failure.
+ * 	For sockets with reuseport option, the **struct bpf_sock**
+ * 	result is from *reuse*\ **->socks**\ [] using the hash of the
+ * 	tuple.
+ */
+static struct bpf_sock *(*bpf_sk_lookup_udp)(void *ctx, struct bpf_sock_tuple *tuple, __u32 tuple_size, __u64 netns, __u64 flags) = (void *) 85;
+
+/*
+ * bpf_sk_release
+ *
+ * 	Release the reference held by *sock*. *sock* must be a
+ * 	non-**NULL** pointer that was returned from
+ * 	**bpf_sk_lookup_xxx**\ ().
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_sk_release)(void *sock) = (void *) 86;
+
+/*
+ * bpf_map_push_elem
+ *
+ * 	Push an element *value* in *map*. *flags* is one of:
+ *
+ * 	**BPF_EXIST**
+ * 		If the queue/stack is full, the oldest element is
+ * 		removed to make room for this.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_map_push_elem)(void *map, const void *value, __u64 flags) = (void *) 87;
+
+/*
+ * bpf_map_pop_elem
+ *
+ * 	Pop an element from *map*.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_map_pop_elem)(void *map, void *value) = (void *) 88;
+
+/*
+ * bpf_map_peek_elem
+ *
+ * 	Get an element from *map* without removing it.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_map_peek_elem)(void *map, void *value) = (void *) 89;
+
+/*
+ * bpf_msg_push_data
+ *
+ * 	For socket policies, insert *len* bytes into *msg* at offset
+ * 	*start*.
+ *
+ * 	If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
+ * 	*msg* it may want to insert metadata or options into the *msg*.
+ * 	This can later be read and used by any of the lower layer BPF
+ * 	hooks.
+ *
+ * 	This helper may fail if under memory pressure (a malloc
+ * 	fails) in these cases BPF programs will get an appropriate
+ * 	error and BPF programs will need to handle them.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_msg_push_data)(struct sk_msg_md *msg, __u32 start, __u32 len, __u64 flags) = (void *) 90;
+
+/*
+ * bpf_msg_pop_data
+ *
+ * 	Will remove *len* bytes from a *msg* starting at byte *start*.
+ * 	This may result in **ENOMEM** errors under certain situations if
+ * 	an allocation and copy are required due to a full ring buffer.
+ * 	However, the helper will try to avoid doing the allocation
+ * 	if possible. Other errors can occur if input parameters are
+ * 	invalid either due to *start* byte not being valid part of *msg*
+ * 	payload and/or *pop* value being to large.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_msg_pop_data)(struct sk_msg_md *msg, __u32 start, __u32 len, __u64 flags) = (void *) 91;
+
+/*
+ * bpf_rc_pointer_rel
+ *
+ * 	This helper is used in programs implementing IR decoding, to
+ * 	report a successfully decoded pointer movement.
+ *
+ * 	The *ctx* should point to the lirc sample as passed into
+ * 	the program.
+ *
+ * 	This helper is only available is the kernel was compiled with
+ * 	the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ * 	"**y**".
+ *
+ * Returns
+ * 	0
+ */
+static long (*bpf_rc_pointer_rel)(void *ctx, __s32 rel_x, __s32 rel_y) = (void *) 92;
+
+/*
+ * bpf_spin_lock
+ *
+ * 	Acquire a spinlock represented by the pointer *lock*, which is
+ * 	stored as part of a value of a map. Taking the lock allows to
+ * 	safely update the rest of the fields in that value. The
+ * 	spinlock can (and must) later be released with a call to
+ * 	**bpf_spin_unlock**\ (\ *lock*\ ).
+ *
+ * 	Spinlocks in BPF programs come with a number of restrictions
+ * 	and constraints:
+ *
+ * 	* **bpf_spin_lock** objects are only allowed inside maps of
+ * 	  types **BPF_MAP_TYPE_HASH** and **BPF_MAP_TYPE_ARRAY** (this
+ * 	  list could be extended in the future).
+ * 	* BTF description of the map is mandatory.
+ * 	* The BPF program can take ONE lock at a time, since taking two
+ * 	  or more could cause dead locks.
+ * 	* Only one **struct bpf_spin_lock** is allowed per map element.
+ * 	* When the lock is taken, calls (either BPF to BPF or helpers)
+ * 	  are not allowed.
+ * 	* The **BPF_LD_ABS** and **BPF_LD_IND** instructions are not
+ * 	  allowed inside a spinlock-ed region.
+ * 	* The BPF program MUST call **bpf_spin_unlock**\ () to release
+ * 	  the lock, on all execution paths, before it returns.
+ * 	* The BPF program can access **struct bpf_spin_lock** only via
+ * 	  the **bpf_spin_lock**\ () and **bpf_spin_unlock**\ ()
+ * 	  helpers. Loading or storing data into the **struct
+ * 	  bpf_spin_lock** *lock*\ **;** field of a map is not allowed.
+ * 	* To use the **bpf_spin_lock**\ () helper, the BTF description
+ * 	  of the map value must be a struct and have **struct
+ * 	  bpf_spin_lock** *anyname*\ **;** field at the top level.
+ * 	  Nested lock inside another struct is not allowed.
+ * 	* The **struct bpf_spin_lock** *lock* field in a map value must
+ * 	  be aligned on a multiple of 4 bytes in that value.
+ * 	* Syscall with command **BPF_MAP_LOOKUP_ELEM** does not copy
+ * 	  the **bpf_spin_lock** field to user space.
+ * 	* Syscall with command **BPF_MAP_UPDATE_ELEM**, or update from
+ * 	  a BPF program, do not update the **bpf_spin_lock** field.
+ * 	* **bpf_spin_lock** cannot be on the stack or inside a
+ * 	  networking packet (it can only be inside of a map values).
+ * 	* **bpf_spin_lock** is available to root only.
+ * 	* Tracing programs and socket filter programs cannot use
+ * 	  **bpf_spin_lock**\ () due to insufficient preemption checks
+ * 	  (but this may change in the future).
+ * 	* **bpf_spin_lock** is not allowed in inner maps of map-in-map.
+ *
+ * Returns
+ * 	0
+ */
+static long (*bpf_spin_lock)(struct bpf_spin_lock *lock) = (void *) 93;
+
+/*
+ * bpf_spin_unlock
+ *
+ * 	Release the *lock* previously locked by a call to
+ * 	**bpf_spin_lock**\ (\ *lock*\ ).
+ *
+ * Returns
+ * 	0
+ */
+static long (*bpf_spin_unlock)(struct bpf_spin_lock *lock) = (void *) 94;
+
+/*
+ * bpf_sk_fullsock
+ *
+ * 	This helper gets a **struct bpf_sock** pointer such
+ * 	that all the fields in this **bpf_sock** can be accessed.
+ *
+ * Returns
+ * 	A **struct bpf_sock** pointer on success, or **NULL** in
+ * 	case of failure.
+ */
+static struct bpf_sock *(*bpf_sk_fullsock)(struct bpf_sock *sk) = (void *) 95;
+
+/*
+ * bpf_tcp_sock
+ *
+ * 	This helper gets a **struct bpf_tcp_sock** pointer from a
+ * 	**struct bpf_sock** pointer.
+ *
+ * Returns
+ * 	A **struct bpf_tcp_sock** pointer on success, or **NULL** in
+ * 	case of failure.
+ */
+static struct bpf_tcp_sock *(*bpf_tcp_sock)(struct bpf_sock *sk) = (void *) 96;
+
+/*
+ * bpf_skb_ecn_set_ce
+ *
+ * 	Set ECN (Explicit Congestion Notification) field of IP header
+ * 	to **CE** (Congestion Encountered) if current value is **ECT**
+ * 	(ECN Capable Transport). Otherwise, do nothing. Works with IPv6
+ * 	and IPv4.
+ *
+ * Returns
+ * 	1 if the **CE** flag is set (either by the current helper call
+ * 	or because it was already present), 0 if it is not set.
+ */
+static long (*bpf_skb_ecn_set_ce)(struct __sk_buff *skb) = (void *) 97;
+
+/*
+ * bpf_get_listener_sock
+ *
+ * 	Return a **struct bpf_sock** pointer in **TCP_LISTEN** state.
+ * 	**bpf_sk_release**\ () is unnecessary and not allowed.
+ *
+ * Returns
+ * 	A **struct bpf_sock** pointer on success, or **NULL** in
+ * 	case of failure.
+ */
+static struct bpf_sock *(*bpf_get_listener_sock)(struct bpf_sock *sk) = (void *) 98;
+
+/*
+ * bpf_skc_lookup_tcp
+ *
+ * 	Look for TCP socket matching *tuple*, optionally in a child
+ * 	network namespace *netns*. The return value must be checked,
+ * 	and if non-**NULL**, released via **bpf_sk_release**\ ().
+ *
+ * 	This function is identical to **bpf_sk_lookup_tcp**\ (), except
+ * 	that it also returns timewait or request sockets. Use
+ * 	**bpf_sk_fullsock**\ () or **bpf_tcp_sock**\ () to access the
+ * 	full structure.
+ *
+ * 	This helper is available only if the kernel was compiled with
+ * 	**CONFIG_NET** configuration option.
+ *
+ * Returns
+ * 	Pointer to **struct bpf_sock**, or **NULL** in case of failure.
+ * 	For sockets with reuseport option, the **struct bpf_sock**
+ * 	result is from *reuse*\ **->socks**\ [] using the hash of the
+ * 	tuple.
+ */
+static struct bpf_sock *(*bpf_skc_lookup_tcp)(void *ctx, struct bpf_sock_tuple *tuple, __u32 tuple_size, __u64 netns, __u64 flags) = (void *) 99;
+
+/*
+ * bpf_tcp_check_syncookie
+ *
+ * 	Check whether *iph* and *th* contain a valid SYN cookie ACK for
+ * 	the listening socket in *sk*.
+ *
+ * 	*iph* points to the start of the IPv4 or IPv6 header, while
+ * 	*iph_len* contains **sizeof**\ (**struct iphdr**) or
+ * 	**sizeof**\ (**struct ipv6hdr**).
+ *
+ * 	*th* points to the start of the TCP header, while *th_len*
+ * 	contains the length of the TCP header (at least
+ * 	**sizeof**\ (**struct tcphdr**)).
+ *
+ * Returns
+ * 	0 if *iph* and *th* are a valid SYN cookie ACK, or a negative
+ * 	error otherwise.
+ */
+static long (*bpf_tcp_check_syncookie)(void *sk, void *iph, __u32 iph_len, struct tcphdr *th, __u32 th_len) = (void *) 100;
+
+/*
+ * bpf_sysctl_get_name
+ *
+ * 	Get name of sysctl in /proc/sys/ and copy it into provided by
+ * 	program buffer *buf* of size *buf_len*.
+ *
+ * 	The buffer is always NUL terminated, unless it's zero-sized.
+ *
+ * 	If *flags* is zero, full name (e.g. "net/ipv4/tcp_mem") is
+ * 	copied. Use **BPF_F_SYSCTL_BASE_NAME** flag to copy base name
+ * 	only (e.g. "tcp_mem").
+ *
+ * Returns
+ * 	Number of character copied (not including the trailing NUL).
+ *
+ * 	**-E2BIG** if the buffer wasn't big enough (*buf* will contain
+ * 	truncated name in this case).
+ */
+static long (*bpf_sysctl_get_name)(struct bpf_sysctl *ctx, char *buf, unsigned long buf_len, __u64 flags) = (void *) 101;
+
+/*
+ * bpf_sysctl_get_current_value
+ *
+ * 	Get current value of sysctl as it is presented in /proc/sys
+ * 	(incl. newline, etc), and copy it as a string into provided
+ * 	by program buffer *buf* of size *buf_len*.
+ *
+ * 	The whole value is copied, no matter what file position user
+ * 	space issued e.g. sys_read at.
+ *
+ * 	The buffer is always NUL terminated, unless it's zero-sized.
+ *
+ * Returns
+ * 	Number of character copied (not including the trailing NUL).
+ *
+ * 	**-E2BIG** if the buffer wasn't big enough (*buf* will contain
+ * 	truncated name in this case).
+ *
+ * 	**-EINVAL** if current value was unavailable, e.g. because
+ * 	sysctl is uninitialized and read returns -EIO for it.
+ */
+static long (*bpf_sysctl_get_current_value)(struct bpf_sysctl *ctx, char *buf, unsigned long buf_len) = (void *) 102;
+
+/*
+ * bpf_sysctl_get_new_value
+ *
+ * 	Get new value being written by user space to sysctl (before
+ * 	the actual write happens) and copy it as a string into
+ * 	provided by program buffer *buf* of size *buf_len*.
+ *
+ * 	User space may write new value at file position > 0.
+ *
+ * 	The buffer is always NUL terminated, unless it's zero-sized.
+ *
+ * Returns
+ * 	Number of character copied (not including the trailing NUL).
+ *
+ * 	**-E2BIG** if the buffer wasn't big enough (*buf* will contain
+ * 	truncated name in this case).
+ *
+ * 	**-EINVAL** if sysctl is being read.
+ */
+static long (*bpf_sysctl_get_new_value)(struct bpf_sysctl *ctx, char *buf, unsigned long buf_len) = (void *) 103;
+
+/*
+ * bpf_sysctl_set_new_value
+ *
+ * 	Override new value being written by user space to sysctl with
+ * 	value provided by program in buffer *buf* of size *buf_len*.
+ *
+ * 	*buf* should contain a string in same form as provided by user
+ * 	space on sysctl write.
+ *
+ * 	User space may write new value at file position > 0. To override
+ * 	the whole sysctl value file position should be set to zero.
+ *
+ * Returns
+ * 	0 on success.
+ *
+ * 	**-E2BIG** if the *buf_len* is too big.
+ *
+ * 	**-EINVAL** if sysctl is being read.
+ */
+static long (*bpf_sysctl_set_new_value)(struct bpf_sysctl *ctx, const char *buf, unsigned long buf_len) = (void *) 104;
+
+/*
+ * bpf_strtol
+ *
+ * 	Convert the initial part of the string from buffer *buf* of
+ * 	size *buf_len* to a long integer according to the given base
+ * 	and save the result in *res*.
+ *
+ * 	The string may begin with an arbitrary amount of white space
+ * 	(as determined by **isspace**\ (3)) followed by a single
+ * 	optional '**-**' sign.
+ *
+ * 	Five least significant bits of *flags* encode base, other bits
+ * 	are currently unused.
+ *
+ * 	Base must be either 8, 10, 16 or 0 to detect it automatically
+ * 	similar to user space **strtol**\ (3).
+ *
+ * Returns
+ * 	Number of characters consumed on success. Must be positive but
+ * 	no more than *buf_len*.
+ *
+ * 	**-EINVAL** if no valid digits were found or unsupported base
+ * 	was provided.
+ *
+ * 	**-ERANGE** if resulting value was out of range.
+ */
+static long (*bpf_strtol)(const char *buf, unsigned long buf_len, __u64 flags, long *res) = (void *) 105;
+
+/*
+ * bpf_strtoul
+ *
+ * 	Convert the initial part of the string from buffer *buf* of
+ * 	size *buf_len* to an unsigned long integer according to the
+ * 	given base and save the result in *res*.
+ *
+ * 	The string may begin with an arbitrary amount of white space
+ * 	(as determined by **isspace**\ (3)).
+ *
+ * 	Five least significant bits of *flags* encode base, other bits
+ * 	are currently unused.
+ *
+ * 	Base must be either 8, 10, 16 or 0 to detect it automatically
+ * 	similar to user space **strtoul**\ (3).
+ *
+ * Returns
+ * 	Number of characters consumed on success. Must be positive but
+ * 	no more than *buf_len*.
+ *
+ * 	**-EINVAL** if no valid digits were found or unsupported base
+ * 	was provided.
+ *
+ * 	**-ERANGE** if resulting value was out of range.
+ */
+static long (*bpf_strtoul)(const char *buf, unsigned long buf_len, __u64 flags, unsigned long *res) = (void *) 106;
+
+/*
+ * bpf_sk_storage_get
+ *
+ * 	Get a bpf-local-storage from a *sk*.
+ *
+ * 	Logically, it could be thought of getting the value from
+ * 	a *map* with *sk* as the **key**.  From this
+ * 	perspective,  the usage is not much different from
+ * 	**bpf_map_lookup_elem**\ (*map*, **&**\ *sk*) except this
+ * 	helper enforces the key must be a full socket and the map must
+ * 	be a **BPF_MAP_TYPE_SK_STORAGE** also.
+ *
+ * 	Underneath, the value is stored locally at *sk* instead of
+ * 	the *map*.  The *map* is used as the bpf-local-storage
+ * 	"type". The bpf-local-storage "type" (i.e. the *map*) is
+ * 	searched against all bpf-local-storages residing at *sk*.
+ *
+ * 	*sk* is a kernel **struct sock** pointer for LSM program.
+ * 	*sk* is a **struct bpf_sock** pointer for other program types.
+ *
+ * 	An optional *flags* (**BPF_SK_STORAGE_GET_F_CREATE**) can be
+ * 	used such that a new bpf-local-storage will be
+ * 	created if one does not exist.  *value* can be used
+ * 	together with **BPF_SK_STORAGE_GET_F_CREATE** to specify
+ * 	the initial value of a bpf-local-storage.  If *value* is
+ * 	**NULL**, the new bpf-local-storage will be zero initialized.
+ *
+ * Returns
+ * 	A bpf-local-storage pointer is returned on success.
+ *
+ * 	**NULL** if not found or there was an error in adding
+ * 	a new bpf-local-storage.
+ */
+static void *(*bpf_sk_storage_get)(void *map, void *sk, void *value, __u64 flags) = (void *) 107;
+
+/*
+ * bpf_sk_storage_delete
+ *
+ * 	Delete a bpf-local-storage from a *sk*.
+ *
+ * Returns
+ * 	0 on success.
+ *
+ * 	**-ENOENT** if the bpf-local-storage cannot be found.
+ * 	**-EINVAL** if sk is not a fullsock (e.g. a request_sock).
+ */
+static long (*bpf_sk_storage_delete)(void *map, void *sk) = (void *) 108;
+
+/*
+ * bpf_send_signal
+ *
+ * 	Send signal *sig* to the process of the current task.
+ * 	The signal may be delivered to any of this process's threads.
+ *
+ * Returns
+ * 	0 on success or successfully queued.
+ *
+ * 	**-EBUSY** if work queue under nmi is full.
+ *
+ * 	**-EINVAL** if *sig* is invalid.
+ *
+ * 	**-EPERM** if no permission to send the *sig*.
+ *
+ * 	**-EAGAIN** if bpf program can try again.
+ */
+static long (*bpf_send_signal)(__u32 sig) = (void *) 109;
+
+/*
+ * bpf_tcp_gen_syncookie
+ *
+ * 	Try to issue a SYN cookie for the packet with corresponding
+ * 	IP/TCP headers, *iph* and *th*, on the listening socket in *sk*.
+ *
+ * 	*iph* points to the start of the IPv4 or IPv6 header, while
+ * 	*iph_len* contains **sizeof**\ (**struct iphdr**) or
+ * 	**sizeof**\ (**struct ipv6hdr**).
+ *
+ * 	*th* points to the start of the TCP header, while *th_len*
+ * 	contains the length of the TCP header with options (at least
+ * 	**sizeof**\ (**struct tcphdr**)).
+ *
+ * Returns
+ * 	On success, lower 32 bits hold the generated SYN cookie in
+ * 	followed by 16 bits which hold the MSS value for that cookie,
+ * 	and the top 16 bits are unused.
+ *
+ * 	On failure, the returned value is one of the following:
+ *
+ * 	**-EINVAL** SYN cookie cannot be issued due to error
+ *
+ * 	**-ENOENT** SYN cookie should not be issued (no SYN flood)
+ *
+ * 	**-EOPNOTSUPP** kernel configuration does not enable SYN cookies
+ *
+ * 	**-EPROTONOSUPPORT** IP packet version is not 4 or 6
+ */
+static __s64 (*bpf_tcp_gen_syncookie)(void *sk, void *iph, __u32 iph_len, struct tcphdr *th, __u32 th_len) = (void *) 110;
+
+/*
+ * bpf_skb_output
+ *
+ * 	Write raw *data* blob into a special BPF perf event held by
+ * 	*map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
+ * 	event must have the following attributes: **PERF_SAMPLE_RAW**
+ * 	as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
+ * 	**PERF_COUNT_SW_BPF_OUTPUT** as **config**.
+ *
+ * 	The *flags* are used to indicate the index in *map* for which
+ * 	the value must be put, masked with **BPF_F_INDEX_MASK**.
+ * 	Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
+ * 	to indicate that the index of the current CPU core should be
+ * 	used.
+ *
+ * 	The value to write, of *size*, is passed through eBPF stack and
+ * 	pointed by *data*.
+ *
+ * 	*ctx* is a pointer to in-kernel struct sk_buff.
+ *
+ * 	This helper is similar to **bpf_perf_event_output**\ () but
+ * 	restricted to raw_tracepoint bpf programs.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_skb_output)(void *ctx, void *map, __u64 flags, void *data, __u64 size) = (void *) 111;
+
+/*
+ * bpf_probe_read_user
+ *
+ * 	Safely attempt to read *size* bytes from user space address
+ * 	*unsafe_ptr* and store the data in *dst*.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_probe_read_user)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 112;
+
+/*
+ * bpf_probe_read_kernel
+ *
+ * 	Safely attempt to read *size* bytes from kernel space address
+ * 	*unsafe_ptr* and store the data in *dst*.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_probe_read_kernel)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 113;
+
+/*
+ * bpf_probe_read_user_str
+ *
+ * 	Copy a NUL terminated string from an unsafe user address
+ * 	*unsafe_ptr* to *dst*. The *size* should include the
+ * 	terminating NUL byte. In case the string length is smaller than
+ * 	*size*, the target is not padded with further NUL bytes. If the
+ * 	string length is larger than *size*, just *size*-1 bytes are
+ * 	copied and the last byte is set to NUL.
+ *
+ * 	On success, returns the number of bytes that were written,
+ * 	including the terminal NUL. This makes this helper useful in
+ * 	tracing programs for reading strings, and more importantly to
+ * 	get its length at runtime. See the following snippet:
+ *
+ * 	::
+ *
+ * 		SEC("kprobe/sys_open")
+ * 		void bpf_sys_open(struct pt_regs *ctx)
+ * 		{
+ * 		        char buf[PATHLEN]; // PATHLEN is defined to 256
+ * 		        int res = bpf_probe_read_user_str(buf, sizeof(buf),
+ * 			                                  ctx->di);
+ *
+ * 			// Consume buf, for example push it to
+ * 			// userspace via bpf_perf_event_output(); we
+ * 			// can use res (the string length) as event
+ * 			// size, after checking its boundaries.
+ * 		}
+ *
+ * 	In comparison, using **bpf_probe_read_user**\ () helper here
+ * 	instead to read the string would require to estimate the length
+ * 	at compile time, and would often result in copying more memory
+ * 	than necessary.
+ *
+ * 	Another useful use case is when parsing individual process
+ * 	arguments or individual environment variables navigating
+ * 	*current*\ **->mm->arg_start** and *current*\
+ * 	**->mm->env_start**: using this helper and the return value,
+ * 	one can quickly iterate at the right offset of the memory area.
+ *
+ * Returns
+ * 	On success, the strictly positive length of the output string,
+ * 	including the trailing NUL character. On error, a negative
+ * 	value.
+ */
+static long (*bpf_probe_read_user_str)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 114;
+
+/*
+ * bpf_probe_read_kernel_str
+ *
+ * 	Copy a NUL terminated string from an unsafe kernel address *unsafe_ptr*
+ * 	to *dst*. Same semantics as with **bpf_probe_read_user_str**\ () apply.
+ *
+ * Returns
+ * 	On success, the strictly positive length of the string, including
+ * 	the trailing NUL character. On error, a negative value.
+ */
+static long (*bpf_probe_read_kernel_str)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 115;
+
+/*
+ * bpf_tcp_send_ack
+ *
+ * 	Send out a tcp-ack. *tp* is the in-kernel struct **tcp_sock**.
+ * 	*rcv_nxt* is the ack_seq to be sent out.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_tcp_send_ack)(void *tp, __u32 rcv_nxt) = (void *) 116;
+
+/*
+ * bpf_send_signal_thread
+ *
+ * 	Send signal *sig* to the thread corresponding to the current task.
+ *
+ * Returns
+ * 	0 on success or successfully queued.
+ *
+ * 	**-EBUSY** if work queue under nmi is full.
+ *
+ * 	**-EINVAL** if *sig* is invalid.
+ *
+ * 	**-EPERM** if no permission to send the *sig*.
+ *
+ * 	**-EAGAIN** if bpf program can try again.
+ */
+static long (*bpf_send_signal_thread)(__u32 sig) = (void *) 117;
+
+/*
+ * bpf_jiffies64
+ *
+ * 	Obtain the 64bit jiffies
+ *
+ * Returns
+ * 	The 64 bit jiffies
+ */
+static __u64 (*bpf_jiffies64)(void) = (void *) 118;
+
+/*
+ * bpf_read_branch_records
+ *
+ * 	For an eBPF program attached to a perf event, retrieve the
+ * 	branch records (**struct perf_branch_entry**) associated to *ctx*
+ * 	and store it in the buffer pointed by *buf* up to size
+ * 	*size* bytes.
+ *
+ * Returns
+ * 	On success, number of bytes written to *buf*. On error, a
+ * 	negative value.
+ *
+ * 	The *flags* can be set to **BPF_F_GET_BRANCH_RECORDS_SIZE** to
+ * 	instead return the number of bytes required to store all the
+ * 	branch entries. If this flag is set, *buf* may be NULL.
+ *
+ * 	**-EINVAL** if arguments invalid or **size** not a multiple
+ * 	of **sizeof**\ (**struct perf_branch_entry**\ ).
+ *
+ * 	**-ENOENT** if architecture does not support branch records.
+ */
+static long (*bpf_read_branch_records)(struct bpf_perf_event_data *ctx, void *buf, __u32 size, __u64 flags) = (void *) 119;
+
+/*
+ * bpf_get_ns_current_pid_tgid
+ *
+ * 	Returns 0 on success, values for *pid* and *tgid* as seen from the current
+ * 	*namespace* will be returned in *nsdata*.
+ *
+ * Returns
+ * 	0 on success, or one of the following in case of failure:
+ *
+ * 	**-EINVAL** if dev and inum supplied don't match dev_t and inode number
+ * 	with nsfs of current task, or if dev conversion to dev_t lost high bits.
+ *
+ * 	**-ENOENT** if pidns does not exists for the current task.
+ */
+static long (*bpf_get_ns_current_pid_tgid)(__u64 dev, __u64 ino, struct bpf_pidns_info *nsdata, __u32 size) = (void *) 120;
+
+/*
+ * bpf_xdp_output
+ *
+ * 	Write raw *data* blob into a special BPF perf event held by
+ * 	*map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
+ * 	event must have the following attributes: **PERF_SAMPLE_RAW**
+ * 	as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
+ * 	**PERF_COUNT_SW_BPF_OUTPUT** as **config**.
+ *
+ * 	The *flags* are used to indicate the index in *map* for which
+ * 	the value must be put, masked with **BPF_F_INDEX_MASK**.
+ * 	Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
+ * 	to indicate that the index of the current CPU core should be
+ * 	used.
+ *
+ * 	The value to write, of *size*, is passed through eBPF stack and
+ * 	pointed by *data*.
+ *
+ * 	*ctx* is a pointer to in-kernel struct xdp_buff.
+ *
+ * 	This helper is similar to **bpf_perf_eventoutput**\ () but
+ * 	restricted to raw_tracepoint bpf programs.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_xdp_output)(void *ctx, void *map, __u64 flags, void *data, __u64 size) = (void *) 121;
+
+/*
+ * bpf_get_netns_cookie
+ *
+ * 	Retrieve the cookie (generated by the kernel) of the network
+ * 	namespace the input *ctx* is associated with. The network
+ * 	namespace cookie remains stable for its lifetime and provides
+ * 	a global identifier that can be assumed unique. If *ctx* is
+ * 	NULL, then the helper returns the cookie for the initial
+ * 	network namespace. The cookie itself is very similar to that
+ * 	of **bpf_get_socket_cookie**\ () helper, but for network
+ * 	namespaces instead of sockets.
+ *
+ * Returns
+ * 	A 8-byte long opaque number.
+ */
+static __u64 (*bpf_get_netns_cookie)(void *ctx) = (void *) 122;
+
+/*
+ * bpf_get_current_ancestor_cgroup_id
+ *
+ * 	Return id of cgroup v2 that is ancestor of the cgroup associated
+ * 	with the current task at the *ancestor_level*. The root cgroup
+ * 	is at *ancestor_level* zero and each step down the hierarchy
+ * 	increments the level. If *ancestor_level* == level of cgroup
+ * 	associated with the current task, then return value will be the
+ * 	same as that of **bpf_get_current_cgroup_id**\ ().
+ *
+ * 	The helper is useful to implement policies based on cgroups
+ * 	that are upper in hierarchy than immediate cgroup associated
+ * 	with the current task.
+ *
+ * 	The format of returned id and helper limitations are same as in
+ * 	**bpf_get_current_cgroup_id**\ ().
+ *
+ * Returns
+ * 	The id is returned or 0 in case the id could not be retrieved.
+ */
+static __u64 (*bpf_get_current_ancestor_cgroup_id)(int ancestor_level) = (void *) 123;
+
+/*
+ * bpf_sk_assign
+ *
+ * 	Helper is overloaded depending on BPF program type. This
+ * 	description applies to **BPF_PROG_TYPE_SCHED_CLS** and
+ * 	**BPF_PROG_TYPE_SCHED_ACT** programs.
+ *
+ * 	Assign the *sk* to the *skb*. When combined with appropriate
+ * 	routing configuration to receive the packet towards the socket,
+ * 	will cause *skb* to be delivered to the specified socket.
+ * 	Subsequent redirection of *skb* via  **bpf_redirect**\ (),
+ * 	**bpf_clone_redirect**\ () or other methods outside of BPF may
+ * 	interfere with successful delivery to the socket.
+ *
+ * 	This operation is only valid from TC ingress path.
+ *
+ * 	The *flags* argument must be zero.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure:
+ *
+ * 	**-EINVAL** if specified *flags* are not supported.
+ *
+ * 	**-ENOENT** if the socket is unavailable for assignment.
+ *
+ * 	**-ENETUNREACH** if the socket is unreachable (wrong netns).
+ *
+ * 	**-EOPNOTSUPP** if the operation is not supported, for example
+ * 	a call from outside of TC ingress.
+ *
+ * 	**-ESOCKTNOSUPPORT** if the socket type is not supported
+ * 	(reuseport).
+ */
+static long (*bpf_sk_assign)(void *ctx, void *sk, __u64 flags) = (void *) 124;
+
+/*
+ * bpf_ktime_get_boot_ns
+ *
+ * 	Return the time elapsed since system boot, in nanoseconds.
+ * 	Does include the time the system was suspended.
+ * 	See: **clock_gettime**\ (**CLOCK_BOOTTIME**)
+ *
+ * Returns
+ * 	Current *ktime*.
+ */
+static __u64 (*bpf_ktime_get_boot_ns)(void) = (void *) 125;
+
+/*
+ * bpf_seq_printf
+ *
+ * 	**bpf_seq_printf**\ () uses seq_file **seq_printf**\ () to print
+ * 	out the format string.
+ * 	The *m* represents the seq_file. The *fmt* and *fmt_size* are for
+ * 	the format string itself. The *data* and *data_len* are format string
+ * 	arguments. The *data* are a **u64** array and corresponding format string
+ * 	values are stored in the array. For strings and pointers where pointees
+ * 	are accessed, only the pointer values are stored in the *data* array.
+ * 	The *data_len* is the size of *data* in bytes - must be a multiple of 8.
+ *
+ * 	Formats **%s**, **%p{i,I}{4,6}** requires to read kernel memory.
+ * 	Reading kernel memory may fail due to either invalid address or
+ * 	valid address but requiring a major memory fault. If reading kernel memory
+ * 	fails, the string for **%s** will be an empty string, and the ip
+ * 	address for **%p{i,I}{4,6}** will be 0. Not returning error to
+ * 	bpf program is consistent with what **bpf_trace_printk**\ () does for now.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure:
+ *
+ * 	**-EBUSY** if per-CPU memory copy buffer is busy, can try again
+ * 	by returning 1 from bpf program.
+ *
+ * 	**-EINVAL** if arguments are invalid, or if *fmt* is invalid/unsupported.
+ *
+ * 	**-E2BIG** if *fmt* contains too many format specifiers.
+ *
+ * 	**-EOVERFLOW** if an overflow happened: The same object will be tried again.
+ */
+static long (*bpf_seq_printf)(struct seq_file *m, const char *fmt, __u32 fmt_size, const void *data, __u32 data_len) = (void *) 126;
+
+/*
+ * bpf_seq_write
+ *
+ * 	**bpf_seq_write**\ () uses seq_file **seq_write**\ () to write the data.
+ * 	The *m* represents the seq_file. The *data* and *len* represent the
+ * 	data to write in bytes.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure:
+ *
+ * 	**-EOVERFLOW** if an overflow happened: The same object will be tried again.
+ */
+static long (*bpf_seq_write)(struct seq_file *m, const void *data, __u32 len) = (void *) 127;
+
+/*
+ * bpf_sk_cgroup_id
+ *
+ * 	Return the cgroup v2 id of the socket *sk*.
+ *
+ * 	*sk* must be a non-**NULL** pointer to a socket, e.g. one
+ * 	returned from **bpf_sk_lookup_xxx**\ (),
+ * 	**bpf_sk_fullsock**\ (), etc. The format of returned id is
+ * 	same as in **bpf_skb_cgroup_id**\ ().
+ *
+ * 	This helper is available only if the kernel was compiled with
+ * 	the **CONFIG_SOCK_CGROUP_DATA** configuration option.
+ *
+ * Returns
+ * 	The id is returned or 0 in case the id could not be retrieved.
+ */
+static __u64 (*bpf_sk_cgroup_id)(void *sk) = (void *) 128;
+
+/*
+ * bpf_sk_ancestor_cgroup_id
+ *
+ * 	Return id of cgroup v2 that is ancestor of cgroup associated
+ * 	with the *sk* at the *ancestor_level*.  The root cgroup is at
+ * 	*ancestor_level* zero and each step down the hierarchy
+ * 	increments the level. If *ancestor_level* == level of cgroup
+ * 	associated with *sk*, then return value will be same as that
+ * 	of **bpf_sk_cgroup_id**\ ().
+ *
+ * 	The helper is useful to implement policies based on cgroups
+ * 	that are upper in hierarchy than immediate cgroup associated
+ * 	with *sk*.
+ *
+ * 	The format of returned id and helper limitations are same as in
+ * 	**bpf_sk_cgroup_id**\ ().
+ *
+ * Returns
+ * 	The id is returned or 0 in case the id could not be retrieved.
+ */
+static __u64 (*bpf_sk_ancestor_cgroup_id)(void *sk, int ancestor_level) = (void *) 129;
+
+/*
+ * bpf_ringbuf_output
+ *
+ * 	Copy *size* bytes from *data* into a ring buffer *ringbuf*.
+ * 	If **BPF_RB_NO_WAKEUP** is specified in *flags*, no notification
+ * 	of new data availability is sent.
+ * 	If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification
+ * 	of new data availability is sent unconditionally.
+ * 	If **0** is specified in *flags*, an adaptive notification
+ * 	of new data availability is sent.
+ *
+ * 	An adaptive notification is a notification sent whenever the user-space
+ * 	process has caught up and consumed all available payloads. In case the user-space
+ * 	process is still processing a previous payload, then no notification is needed
+ * 	as it will process the newly added payload automatically.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_ringbuf_output)(void *ringbuf, void *data, __u64 size, __u64 flags) = (void *) 130;
+
+/*
+ * bpf_ringbuf_reserve
+ *
+ * 	Reserve *size* bytes of payload in a ring buffer *ringbuf*.
+ * 	*flags* must be 0.
+ *
+ * Returns
+ * 	Valid pointer with *size* bytes of memory available; NULL,
+ * 	otherwise.
+ */
+static void *(*bpf_ringbuf_reserve)(void *ringbuf, __u64 size, __u64 flags) = (void *) 131;
+
+/*
+ * bpf_ringbuf_submit
+ *
+ * 	Submit reserved ring buffer sample, pointed to by *data*.
+ * 	If **BPF_RB_NO_WAKEUP** is specified in *flags*, no notification
+ * 	of new data availability is sent.
+ * 	If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification
+ * 	of new data availability is sent unconditionally.
+ * 	If **0** is specified in *flags*, an adaptive notification
+ * 	of new data availability is sent.
+ *
+ * 	See 'bpf_ringbuf_output()' for the definition of adaptive notification.
+ *
+ * Returns
+ * 	Nothing. Always succeeds.
+ */
+static void (*bpf_ringbuf_submit)(void *data, __u64 flags) = (void *) 132;
+
+/*
+ * bpf_ringbuf_discard
+ *
+ * 	Discard reserved ring buffer sample, pointed to by *data*.
+ * 	If **BPF_RB_NO_WAKEUP** is specified in *flags*, no notification
+ * 	of new data availability is sent.
+ * 	If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification
+ * 	of new data availability is sent unconditionally.
+ * 	If **0** is specified in *flags*, an adaptive notification
+ * 	of new data availability is sent.
+ *
+ * 	See 'bpf_ringbuf_output()' for the definition of adaptive notification.
+ *
+ * Returns
+ * 	Nothing. Always succeeds.
+ */
+static void (*bpf_ringbuf_discard)(void *data, __u64 flags) = (void *) 133;
+
+/*
+ * bpf_ringbuf_query
+ *
+ * 	Query various characteristics of provided ring buffer. What
+ * 	exactly is queries is determined by *flags*:
+ *
+ * 	* **BPF_RB_AVAIL_DATA**: Amount of data not yet consumed.
+ * 	* **BPF_RB_RING_SIZE**: The size of ring buffer.
+ * 	* **BPF_RB_CONS_POS**: Consumer position (can wrap around).
+ * 	* **BPF_RB_PROD_POS**: Producer(s) position (can wrap around).
+ *
+ * 	Data returned is just a momentary snapshot of actual values
+ * 	and could be inaccurate, so this facility should be used to
+ * 	power heuristics and for reporting, not to make 100% correct
+ * 	calculation.
+ *
+ * Returns
+ * 	Requested value, or 0, if *flags* are not recognized.
+ */
+static __u64 (*bpf_ringbuf_query)(void *ringbuf, __u64 flags) = (void *) 134;
+
+/*
+ * bpf_csum_level
+ *
+ * 	Change the skbs checksum level by one layer up or down, or
+ * 	reset it entirely to none in order to have the stack perform
+ * 	checksum validation. The level is applicable to the following
+ * 	protocols: TCP, UDP, GRE, SCTP, FCOE. For example, a decap of
+ * 	| ETH | IP | UDP | GUE | IP | TCP | into | ETH | IP | TCP |
+ * 	through **bpf_skb_adjust_room**\ () helper with passing in
+ * 	**BPF_F_ADJ_ROOM_NO_CSUM_RESET** flag would require one	call
+ * 	to **bpf_csum_level**\ () with **BPF_CSUM_LEVEL_DEC** since
+ * 	the UDP header is removed. Similarly, an encap of the latter
+ * 	into the former could be accompanied by a helper call to
+ * 	**bpf_csum_level**\ () with **BPF_CSUM_LEVEL_INC** if the
+ * 	skb is still intended to be processed in higher layers of the
+ * 	stack instead of just egressing at tc.
+ *
+ * 	There are three supported level settings at this time:
+ *
+ * 	* **BPF_CSUM_LEVEL_INC**: Increases skb->csum_level for skbs
+ * 	  with CHECKSUM_UNNECESSARY.
+ * 	* **BPF_CSUM_LEVEL_DEC**: Decreases skb->csum_level for skbs
+ * 	  with CHECKSUM_UNNECESSARY.
+ * 	* **BPF_CSUM_LEVEL_RESET**: Resets skb->csum_level to 0 and
+ * 	  sets CHECKSUM_NONE to force checksum validation by the stack.
+ * 	* **BPF_CSUM_LEVEL_QUERY**: No-op, returns the current
+ * 	  skb->csum_level.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure. In the
+ * 	case of **BPF_CSUM_LEVEL_QUERY**, the current skb->csum_level
+ * 	is returned or the error code -EACCES in case the skb is not
+ * 	subject to CHECKSUM_UNNECESSARY.
+ */
+static long (*bpf_csum_level)(struct __sk_buff *skb, __u64 level) = (void *) 135;
+
+/*
+ * bpf_skc_to_tcp6_sock
+ *
+ * 	Dynamically cast a *sk* pointer to a *tcp6_sock* pointer.
+ *
+ * Returns
+ * 	*sk* if casting is valid, or **NULL** otherwise.
+ */
+static struct tcp6_sock *(*bpf_skc_to_tcp6_sock)(void *sk) = (void *) 136;
+
+/*
+ * bpf_skc_to_tcp_sock
+ *
+ * 	Dynamically cast a *sk* pointer to a *tcp_sock* pointer.
+ *
+ * Returns
+ * 	*sk* if casting is valid, or **NULL** otherwise.
+ */
+static struct tcp_sock *(*bpf_skc_to_tcp_sock)(void *sk) = (void *) 137;
+
+/*
+ * bpf_skc_to_tcp_timewait_sock
+ *
+ * 	Dynamically cast a *sk* pointer to a *tcp_timewait_sock* pointer.
+ *
+ * Returns
+ * 	*sk* if casting is valid, or **NULL** otherwise.
+ */
+static struct tcp_timewait_sock *(*bpf_skc_to_tcp_timewait_sock)(void *sk) = (void *) 138;
+
+/*
+ * bpf_skc_to_tcp_request_sock
+ *
+ * 	Dynamically cast a *sk* pointer to a *tcp_request_sock* pointer.
+ *
+ * Returns
+ * 	*sk* if casting is valid, or **NULL** otherwise.
+ */
+static struct tcp_request_sock *(*bpf_skc_to_tcp_request_sock)(void *sk) = (void *) 139;
+
+/*
+ * bpf_skc_to_udp6_sock
+ *
+ * 	Dynamically cast a *sk* pointer to a *udp6_sock* pointer.
+ *
+ * Returns
+ * 	*sk* if casting is valid, or **NULL** otherwise.
+ */
+static struct udp6_sock *(*bpf_skc_to_udp6_sock)(void *sk) = (void *) 140;
+
+/*
+ * bpf_get_task_stack
+ *
+ * 	Return a user or a kernel stack in bpf program provided buffer.
+ * 	To achieve this, the helper needs *task*, which is a valid
+ * 	pointer to **struct task_struct**. To store the stacktrace, the
+ * 	bpf program provides *buf* with a nonnegative *size*.
+ *
+ * 	The last argument, *flags*, holds the number of stack frames to
+ * 	skip (from 0 to 255), masked with
+ * 	**BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
+ * 	the following flags:
+ *
+ * 	**BPF_F_USER_STACK**
+ * 		Collect a user space stack instead of a kernel stack.
+ * 	**BPF_F_USER_BUILD_ID**
+ * 		Collect buildid+offset instead of ips for user stack,
+ * 		only valid if **BPF_F_USER_STACK** is also specified.
+ *
+ * 	**bpf_get_task_stack**\ () can collect up to
+ * 	**PERF_MAX_STACK_DEPTH** both kernel and user frames, subject
+ * 	to sufficient large buffer size. Note that
+ * 	this limit can be controlled with the **sysctl** program, and
+ * 	that it should be manually increased in order to profile long
+ * 	user stacks (such as stacks for Java programs). To do so, use:
+ *
+ * 	::
+ *
+ * 		# sysctl kernel.perf_event_max_stack=<new value>
+ *
+ * Returns
+ * 	The non-negative copied *buf* length equal to or less than
+ * 	*size* on success, or a negative error in case of failure.
+ */
+static long (*bpf_get_task_stack)(struct task_struct *task, void *buf, __u32 size, __u64 flags) = (void *) 141;
+
+/*
+ * bpf_load_hdr_opt
+ *
+ * 	Load header option.  Support reading a particular TCP header
+ * 	option for bpf program (**BPF_PROG_TYPE_SOCK_OPS**).
+ *
+ * 	If *flags* is 0, it will search the option from the
+ * 	*skops*\ **->skb_data**.  The comment in **struct bpf_sock_ops**
+ * 	has details on what skb_data contains under different
+ * 	*skops*\ **->op**.
+ *
+ * 	The first byte of the *searchby_res* specifies the
+ * 	kind that it wants to search.
+ *
+ * 	If the searching kind is an experimental kind
+ * 	(i.e. 253 or 254 according to RFC6994).  It also
+ * 	needs to specify the "magic" which is either
+ * 	2 bytes or 4 bytes.  It then also needs to
+ * 	specify the size of the magic by using
+ * 	the 2nd byte which is "kind-length" of a TCP
+ * 	header option and the "kind-length" also
+ * 	includes the first 2 bytes "kind" and "kind-length"
+ * 	itself as a normal TCP header option also does.
+ *
+ * 	For example, to search experimental kind 254 with
+ * 	2 byte magic 0xeB9F, the searchby_res should be
+ * 	[ 254, 4, 0xeB, 0x9F, 0, 0, .... 0 ].
+ *
+ * 	To search for the standard window scale option (3),
+ * 	the *searchby_res* should be [ 3, 0, 0, .... 0 ].
+ * 	Note, kind-length must be 0 for regular option.
+ *
+ * 	Searching for No-Op (0) and End-of-Option-List (1) are
+ * 	not supported.
+ *
+ * 	*len* must be at least 2 bytes which is the minimal size
+ * 	of a header option.
+ *
+ * 	Supported flags:
+ *
+ * 	* **BPF_LOAD_HDR_OPT_TCP_SYN** to search from the
+ * 	  saved_syn packet or the just-received syn packet.
+ *
+ *
+ * Returns
+ * 	> 0 when found, the header option is copied to *searchby_res*.
+ * 	The return value is the total length copied. On failure, a
+ * 	negative error code is returned:
+ *
+ * 	**-EINVAL** if a parameter is invalid.
+ *
+ * 	**-ENOMSG** if the option is not found.
+ *
+ * 	**-ENOENT** if no syn packet is available when
+ * 	**BPF_LOAD_HDR_OPT_TCP_SYN** is used.
+ *
+ * 	**-ENOSPC** if there is not enough space.  Only *len* number of
+ * 	bytes are copied.
+ *
+ * 	**-EFAULT** on failure to parse the header options in the
+ * 	packet.
+ *
+ * 	**-EPERM** if the helper cannot be used under the current
+ * 	*skops*\ **->op**.
+ */
+static long (*bpf_load_hdr_opt)(struct bpf_sock_ops *skops, void *searchby_res, __u32 len, __u64 flags) = (void *) 142;
+
+/*
+ * bpf_store_hdr_opt
+ *
+ * 	Store header option.  The data will be copied
+ * 	from buffer *from* with length *len* to the TCP header.
+ *
+ * 	The buffer *from* should have the whole option that
+ * 	includes the kind, kind-length, and the actual
+ * 	option data.  The *len* must be at least kind-length
+ * 	long.  The kind-length does not have to be 4 byte
+ * 	aligned.  The kernel will take care of the padding
+ * 	and setting the 4 bytes aligned value to th->doff.
+ *
+ * 	This helper will check for duplicated option
+ * 	by searching the same option in the outgoing skb.
+ *
+ * 	This helper can only be called during
+ * 	**BPF_SOCK_OPS_WRITE_HDR_OPT_CB**.
+ *
+ *
+ * Returns
+ * 	0 on success, or negative error in case of failure:
+ *
+ * 	**-EINVAL** If param is invalid.
+ *
+ * 	**-ENOSPC** if there is not enough space in the header.
+ * 	Nothing has been written
+ *
+ * 	**-EEXIST** if the option already exists.
+ *
+ * 	**-EFAULT** on failure to parse the existing header options.
+ *
+ * 	**-EPERM** if the helper cannot be used under the current
+ * 	*skops*\ **->op**.
+ */
+static long (*bpf_store_hdr_opt)(struct bpf_sock_ops *skops, const void *from, __u32 len, __u64 flags) = (void *) 143;
+
+/*
+ * bpf_reserve_hdr_opt
+ *
+ * 	Reserve *len* bytes for the bpf header option.  The
+ * 	space will be used by **bpf_store_hdr_opt**\ () later in
+ * 	**BPF_SOCK_OPS_WRITE_HDR_OPT_CB**.
+ *
+ * 	If **bpf_reserve_hdr_opt**\ () is called multiple times,
+ * 	the total number of bytes will be reserved.
+ *
+ * 	This helper can only be called during
+ * 	**BPF_SOCK_OPS_HDR_OPT_LEN_CB**.
+ *
+ *
+ * Returns
+ * 	0 on success, or negative error in case of failure:
+ *
+ * 	**-EINVAL** if a parameter is invalid.
+ *
+ * 	**-ENOSPC** if there is not enough space in the header.
+ *
+ * 	**-EPERM** if the helper cannot be used under the current
+ * 	*skops*\ **->op**.
+ */
+static long (*bpf_reserve_hdr_opt)(struct bpf_sock_ops *skops, __u32 len, __u64 flags) = (void *) 144;
+
+/*
+ * bpf_inode_storage_get
+ *
+ * 	Get a bpf_local_storage from an *inode*.
+ *
+ * 	Logically, it could be thought of as getting the value from
+ * 	a *map* with *inode* as the **key**.  From this
+ * 	perspective,  the usage is not much different from
+ * 	**bpf_map_lookup_elem**\ (*map*, **&**\ *inode*) except this
+ * 	helper enforces the key must be an inode and the map must also
+ * 	be a **BPF_MAP_TYPE_INODE_STORAGE**.
+ *
+ * 	Underneath, the value is stored locally at *inode* instead of
+ * 	the *map*.  The *map* is used as the bpf-local-storage
+ * 	"type". The bpf-local-storage "type" (i.e. the *map*) is
+ * 	searched against all bpf_local_storage residing at *inode*.
+ *
+ * 	An optional *flags* (**BPF_LOCAL_STORAGE_GET_F_CREATE**) can be
+ * 	used such that a new bpf_local_storage will be
+ * 	created if one does not exist.  *value* can be used
+ * 	together with **BPF_LOCAL_STORAGE_GET_F_CREATE** to specify
+ * 	the initial value of a bpf_local_storage.  If *value* is
+ * 	**NULL**, the new bpf_local_storage will be zero initialized.
+ *
+ * Returns
+ * 	A bpf_local_storage pointer is returned on success.
+ *
+ * 	**NULL** if not found or there was an error in adding
+ * 	a new bpf_local_storage.
+ */
+static void *(*bpf_inode_storage_get)(void *map, void *inode, void *value, __u64 flags) = (void *) 145;
+
+/*
+ * bpf_inode_storage_delete
+ *
+ * 	Delete a bpf_local_storage from an *inode*.
+ *
+ * Returns
+ * 	0 on success.
+ *
+ * 	**-ENOENT** if the bpf_local_storage cannot be found.
+ */
+static int (*bpf_inode_storage_delete)(void *map, void *inode) = (void *) 146;
+
+/*
+ * bpf_d_path
+ *
+ * 	Return full path for given **struct path** object, which
+ * 	needs to be the kernel BTF *path* object. The path is
+ * 	returned in the provided buffer *buf* of size *sz* and
+ * 	is zero terminated.
+ *
+ *
+ * Returns
+ * 	On success, the strictly positive length of the string,
+ * 	including the trailing NUL character. On error, a negative
+ * 	value.
+ */
+static long (*bpf_d_path)(struct path *path, char *buf, __u32 sz) = (void *) 147;
+
+/*
+ * bpf_copy_from_user
+ *
+ * 	Read *size* bytes from user space address *user_ptr* and store
+ * 	the data in *dst*. This is a wrapper of **copy_from_user**\ ().
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_copy_from_user)(void *dst, __u32 size, const void *user_ptr) = (void *) 148;
+
+/*
+ * bpf_snprintf_btf
+ *
+ * 	Use BTF to store a string representation of *ptr*->ptr in *str*,
+ * 	using *ptr*->type_id.  This value should specify the type
+ * 	that *ptr*->ptr points to. LLVM __builtin_btf_type_id(type, 1)
+ * 	can be used to look up vmlinux BTF type ids. Traversing the
+ * 	data structure using BTF, the type information and values are
+ * 	stored in the first *str_size* - 1 bytes of *str*.  Safe copy of
+ * 	the pointer data is carried out to avoid kernel crashes during
+ * 	operation.  Smaller types can use string space on the stack;
+ * 	larger programs can use map data to store the string
+ * 	representation.
+ *
+ * 	The string can be subsequently shared with userspace via
+ * 	bpf_perf_event_output() or ring buffer interfaces.
+ * 	bpf_trace_printk() is to be avoided as it places too small
+ * 	a limit on string size to be useful.
+ *
+ * 	*flags* is a combination of
+ *
+ * 	**BTF_F_COMPACT**
+ * 		no formatting around type information
+ * 	**BTF_F_NONAME**
+ * 		no struct/union member names/types
+ * 	**BTF_F_PTR_RAW**
+ * 		show raw (unobfuscated) pointer values;
+ * 		equivalent to printk specifier %px.
+ * 	**BTF_F_ZERO**
+ * 		show zero-valued struct/union members; they
+ * 		are not displayed by default
+ *
+ *
+ * Returns
+ * 	The number of bytes that were written (or would have been
+ * 	written if output had to be truncated due to string size),
+ * 	or a negative error in cases of failure.
+ */
+static long (*bpf_snprintf_btf)(char *str, __u32 str_size, struct btf_ptr *ptr, __u32 btf_ptr_size, __u64 flags) = (void *) 149;
+
+/*
+ * bpf_seq_printf_btf
+ *
+ * 	Use BTF to write to seq_write a string representation of
+ * 	*ptr*->ptr, using *ptr*->type_id as per bpf_snprintf_btf().
+ * 	*flags* are identical to those used for bpf_snprintf_btf.
+ *
+ * Returns
+ * 	0 on success or a negative error in case of failure.
+ */
+static long (*bpf_seq_printf_btf)(struct seq_file *m, struct btf_ptr *ptr, __u32 ptr_size, __u64 flags) = (void *) 150;
+
+/*
+ * bpf_skb_cgroup_classid
+ *
+ * 	See **bpf_get_cgroup_classid**\ () for the main description.
+ * 	This helper differs from **bpf_get_cgroup_classid**\ () in that
+ * 	the cgroup v1 net_cls class is retrieved only from the *skb*'s
+ * 	associated socket instead of the current process.
+ *
+ * Returns
+ * 	The id is returned or 0 in case the id could not be retrieved.
+ */
+static __u64 (*bpf_skb_cgroup_classid)(struct __sk_buff *skb) = (void *) 151;
+
+/*
+ * bpf_redirect_neigh
+ *
+ * 	Redirect the packet to another net device of index *ifindex*
+ * 	and fill in L2 addresses from neighboring subsystem. This helper
+ * 	is somewhat similar to **bpf_redirect**\ (), except that it
+ * 	populates L2 addresses as well, meaning, internally, the helper
+ * 	relies on the neighbor lookup for the L2 address of the nexthop.
+ *
+ * 	The helper will perform a FIB lookup based on the skb's
+ * 	networking header to get the address of the next hop, unless
+ * 	this is supplied by the caller in the *params* argument. The
+ * 	*plen* argument indicates the len of *params* and should be set
+ * 	to 0 if *params* is NULL.
+ *
+ * 	The *flags* argument is reserved and must be 0. The helper is
+ * 	currently only supported for tc BPF program types, and enabled
+ * 	for IPv4 and IPv6 protocols.
+ *
+ * Returns
+ * 	The helper returns **TC_ACT_REDIRECT** on success or
+ * 	**TC_ACT_SHOT** on error.
+ */
+static long (*bpf_redirect_neigh)(__u32 ifindex, struct bpf_redir_neigh *params, int plen, __u64 flags) = (void *) 152;
+
+/*
+ * bpf_per_cpu_ptr
+ *
+ * 	Take a pointer to a percpu ksym, *percpu_ptr*, and return a
+ * 	pointer to the percpu kernel variable on *cpu*. A ksym is an
+ * 	extern variable decorated with '__ksym'. For ksym, there is a
+ * 	global var (either static or global) defined of the same name
+ * 	in the kernel. The ksym is percpu if the global var is percpu.
+ * 	The returned pointer points to the global percpu var on *cpu*.
+ *
+ * 	bpf_per_cpu_ptr() has the same semantic as per_cpu_ptr() in the
+ * 	kernel, except that bpf_per_cpu_ptr() may return NULL. This
+ * 	happens if *cpu* is larger than nr_cpu_ids. The caller of
+ * 	bpf_per_cpu_ptr() must check the returned value.
+ *
+ * Returns
+ * 	A pointer pointing to the kernel percpu variable on *cpu*, or
+ * 	NULL, if *cpu* is invalid.
+ */
+static void *(*bpf_per_cpu_ptr)(const void *percpu_ptr, __u32 cpu) = (void *) 153;
+
+/*
+ * bpf_this_cpu_ptr
+ *
+ * 	Take a pointer to a percpu ksym, *percpu_ptr*, and return a
+ * 	pointer to the percpu kernel variable on this cpu. See the
+ * 	description of 'ksym' in **bpf_per_cpu_ptr**\ ().
+ *
+ * 	bpf_this_cpu_ptr() has the same semantic as this_cpu_ptr() in
+ * 	the kernel. Different from **bpf_per_cpu_ptr**\ (), it would
+ * 	never return NULL.
+ *
+ * Returns
+ * 	A pointer pointing to the kernel percpu variable on this cpu.
+ */
+static void *(*bpf_this_cpu_ptr)(const void *percpu_ptr) = (void *) 154;
+
+/*
+ * bpf_redirect_peer
+ *
+ * 	Redirect the packet to another net device of index *ifindex*.
+ * 	This helper is somewhat similar to **bpf_redirect**\ (), except
+ * 	that the redirection happens to the *ifindex*' peer device and
+ * 	the netns switch takes place from ingress to ingress without
+ * 	going through the CPU's backlog queue.
+ *
+ * 	The *flags* argument is reserved and must be 0. The helper is
+ * 	currently only supported for tc BPF program types at the ingress
+ * 	hook and for veth device types. The peer device must reside in a
+ * 	different network namespace.
+ *
+ * Returns
+ * 	The helper returns **TC_ACT_REDIRECT** on success or
+ * 	**TC_ACT_SHOT** on error.
+ */
+static long (*bpf_redirect_peer)(__u32 ifindex, __u64 flags) = (void *) 155;
+
+/*
+ * bpf_task_storage_get
+ *
+ * 	Get a bpf_local_storage from the *task*.
+ *
+ * 	Logically, it could be thought of as getting the value from
+ * 	a *map* with *task* as the **key**.  From this
+ * 	perspective,  the usage is not much different from
+ * 	**bpf_map_lookup_elem**\ (*map*, **&**\ *task*) except this
+ * 	helper enforces the key must be a task_struct and the map must also
+ * 	be a **BPF_MAP_TYPE_TASK_STORAGE**.
+ *
+ * 	Underneath, the value is stored locally at *task* instead of
+ * 	the *map*.  The *map* is used as the bpf-local-storage
+ * 	"type". The bpf-local-storage "type" (i.e. the *map*) is
+ * 	searched against all bpf_local_storage residing at *task*.
+ *
+ * 	An optional *flags* (**BPF_LOCAL_STORAGE_GET_F_CREATE**) can be
+ * 	used such that a new bpf_local_storage will be
+ * 	created if one does not exist.  *value* can be used
+ * 	together with **BPF_LOCAL_STORAGE_GET_F_CREATE** to specify
+ * 	the initial value of a bpf_local_storage.  If *value* is
+ * 	**NULL**, the new bpf_local_storage will be zero initialized.
+ *
+ * Returns
+ * 	A bpf_local_storage pointer is returned on success.
+ *
+ * 	**NULL** if not found or there was an error in adding
+ * 	a new bpf_local_storage.
+ */
+static void *(*bpf_task_storage_get)(void *map, struct task_struct *task, void *value, __u64 flags) = (void *) 156;
+
+/*
+ * bpf_task_storage_delete
+ *
+ * 	Delete a bpf_local_storage from a *task*.
+ *
+ * Returns
+ * 	0 on success.
+ *
+ * 	**-ENOENT** if the bpf_local_storage cannot be found.
+ */
+static long (*bpf_task_storage_delete)(void *map, struct task_struct *task) = (void *) 157;
+
+/*
+ * bpf_get_current_task_btf
+ *
+ * 	Return a BTF pointer to the "current" task.
+ * 	This pointer can also be used in helpers that accept an
+ * 	*ARG_PTR_TO_BTF_ID* of type *task_struct*.
+ *
+ * Returns
+ * 	Pointer to the current task.
+ */
+static struct task_struct *(*bpf_get_current_task_btf)(void) = (void *) 158;
+
+/*
+ * bpf_bprm_opts_set
+ *
+ * 	Set or clear certain options on *bprm*:
+ *
+ * 	**BPF_F_BPRM_SECUREEXEC** Set the secureexec bit
+ * 	which sets the **AT_SECURE** auxv for glibc. The bit
+ * 	is cleared if the flag is not specified.
+ *
+ * Returns
+ * 	**-EINVAL** if invalid *flags* are passed, zero otherwise.
+ */
+static long (*bpf_bprm_opts_set)(struct linux_binprm *bprm, __u64 flags) = (void *) 159;
+
+/*
+ * bpf_ktime_get_coarse_ns
+ *
+ * 	Return a coarse-grained version of the time elapsed since
+ * 	system boot, in nanoseconds. Does not include time the system
+ * 	was suspended.
+ *
+ * 	See: **clock_gettime**\ (**CLOCK_MONOTONIC_COARSE**)
+ *
+ * Returns
+ * 	Current *ktime*.
+ */
+static __u64 (*bpf_ktime_get_coarse_ns)(void) = (void *) 160;
+
+/*
+ * bpf_ima_inode_hash
+ *
+ * 	Returns the stored IMA hash of the *inode* (if it's available).
+ * 	If the hash is larger than *size*, then only *size*
+ * 	bytes will be copied to *dst*
+ *
+ * Returns
+ * 	The **hash_algo** is returned on success,
+ * 	**-EOPNOTSUP** if IMA is disabled or **-EINVAL** if
+ * 	invalid arguments are passed.
+ */
+static long (*bpf_ima_inode_hash)(struct inode *inode, void *dst, __u32 size) = (void *) 161;
+
+/*
+ * bpf_sock_from_file
+ *
+ * 	If the given file represents a socket, returns the associated
+ * 	socket.
+ *
+ * Returns
+ * 	A pointer to a struct socket on success or NULL if the file is
+ * 	not a socket.
+ */
+static struct socket *(*bpf_sock_from_file)(struct file *file) = (void *) 162;
+
+/*
+ * bpf_check_mtu
+ *
+ * 	Check packet size against exceeding MTU of net device (based
+ * 	on *ifindex*).  This helper will likely be used in combination
+ * 	with helpers that adjust/change the packet size.
+ *
+ * 	The argument *len_diff* can be used for querying with a planned
+ * 	size change. This allows to check MTU prior to changing packet
+ * 	ctx. Providing a *len_diff* adjustment that is larger than the
+ * 	actual packet size (resulting in negative packet size) will in
+ * 	principle not exceed the MTU, which is why it is not considered
+ * 	a failure.  Other BPF helpers are needed for performing the
+ * 	planned size change; therefore the responsibility for catching
+ * 	a negative packet size belongs in those helpers.
+ *
+ * 	Specifying *ifindex* zero means the MTU check is performed
+ * 	against the current net device.  This is practical if this isn't
+ * 	used prior to redirect.
+ *
+ * 	On input *mtu_len* must be a valid pointer, else verifier will
+ * 	reject BPF program.  If the value *mtu_len* is initialized to
+ * 	zero then the ctx packet size is use.  When value *mtu_len* is
+ * 	provided as input this specify the L3 length that the MTU check
+ * 	is done against. Remember XDP and TC length operate at L2, but
+ * 	this value is L3 as this correlate to MTU and IP-header tot_len
+ * 	values which are L3 (similar behavior as bpf_fib_lookup).
+ *
+ * 	The Linux kernel route table can configure MTUs on a more
+ * 	specific per route level, which is not provided by this helper.
+ * 	For route level MTU checks use the **bpf_fib_lookup**\ ()
+ * 	helper.
+ *
+ * 	*ctx* is either **struct xdp_md** for XDP programs or
+ * 	**struct sk_buff** for tc cls_act programs.
+ *
+ * 	The *flags* argument can be a combination of one or more of the
+ * 	following values:
+ *
+ * 	**BPF_MTU_CHK_SEGS**
+ * 		This flag will only works for *ctx* **struct sk_buff**.
+ * 		If packet context contains extra packet segment buffers
+ * 		(often knows as GSO skb), then MTU check is harder to
+ * 		check at this point, because in transmit path it is
+ * 		possible for the skb packet to get re-segmented
+ * 		(depending on net device features).  This could still be
+ * 		a MTU violation, so this flag enables performing MTU
+ * 		check against segments, with a different violation
+ * 		return code to tell it apart. Check cannot use len_diff.
+ *
+ * 	On return *mtu_len* pointer contains the MTU value of the net
+ * 	device.  Remember the net device configured MTU is the L3 size,
+ * 	which is returned here and XDP and TC length operate at L2.
+ * 	Helper take this into account for you, but remember when using
+ * 	MTU value in your BPF-code.
+ *
+ *
+ * Returns
+ * 	* 0 on success, and populate MTU value in *mtu_len* pointer.
+ *
+ * 	* < 0 if any input argument is invalid (*mtu_len* not updated)
+ *
+ * 	MTU violations return positive values, but also populate MTU
+ * 	value in *mtu_len* pointer, as this can be needed for
+ * 	implementing PMTU handing:
+ *
+ * 	* **BPF_MTU_CHK_RET_FRAG_NEEDED**
+ * 	* **BPF_MTU_CHK_RET_SEGS_TOOBIG**
+ */
+static long (*bpf_check_mtu)(void *ctx, __u32 ifindex, __u32 *mtu_len, __s32 len_diff, __u64 flags) = (void *) 163;
+
+/*
+ * bpf_for_each_map_elem
+ *
+ * 	For each element in **map**, call **callback_fn** function with
+ * 	**map**, **callback_ctx** and other map-specific parameters.
+ * 	The **callback_fn** should be a static function and
+ * 	the **callback_ctx** should be a pointer to the stack.
+ * 	The **flags** is used to control certain aspects of the helper.
+ * 	Currently, the **flags** must be 0.
+ *
+ * 	The following are a list of supported map types and their
+ * 	respective expected callback signatures:
+ *
+ * 	BPF_MAP_TYPE_HASH, BPF_MAP_TYPE_PERCPU_HASH,
+ * 	BPF_MAP_TYPE_LRU_HASH, BPF_MAP_TYPE_LRU_PERCPU_HASH,
+ * 	BPF_MAP_TYPE_ARRAY, BPF_MAP_TYPE_PERCPU_ARRAY
+ *
+ * 	long (\*callback_fn)(struct bpf_map \*map, const void \*key, void \*value, void \*ctx);
+ *
+ * 	For per_cpu maps, the map_value is the value on the cpu where the
+ * 	bpf_prog is running.
+ *
+ * 	If **callback_fn** return 0, the helper will continue to the next
+ * 	element. If return value is 1, the helper will skip the rest of
+ * 	elements and return. Other return values are not used now.
+ *
+ *
+ * Returns
+ * 	The number of traversed map elements for success, **-EINVAL** for
+ * 	invalid **flags**.
+ */
+static long (*bpf_for_each_map_elem)(void *map, void *callback_fn, void *callback_ctx, __u64 flags) = (void *) 164;
+
+/*
+ * bpf_snprintf
+ *
+ * 	Outputs a string into the **str** buffer of size **str_size**
+ * 	based on a format string stored in a read-only map pointed by
+ * 	**fmt**.
+ *
+ * 	Each format specifier in **fmt** corresponds to one u64 element
+ * 	in the **data** array. For strings and pointers where pointees
+ * 	are accessed, only the pointer values are stored in the *data*
+ * 	array. The *data_len* is the size of *data* in bytes - must be
+ * 	a multiple of 8.
+ *
+ * 	Formats **%s** and **%p{i,I}{4,6}** require to read kernel
+ * 	memory. Reading kernel memory may fail due to either invalid
+ * 	address or valid address but requiring a major memory fault. If
+ * 	reading kernel memory fails, the string for **%s** will be an
+ * 	empty string, and the ip address for **%p{i,I}{4,6}** will be 0.
+ * 	Not returning error to bpf program is consistent with what
+ * 	**bpf_trace_printk**\ () does for now.
+ *
+ *
+ * Returns
+ * 	The strictly positive length of the formatted string, including
+ * 	the trailing zero character. If the return value is greater than
+ * 	**str_size**, **str** contains a truncated string, guaranteed to
+ * 	be zero-terminated except when **str_size** is 0.
+ *
+ * 	Or **-EBUSY** if the per-CPU memory copy buffer is busy.
+ */
+static long (*bpf_snprintf)(char *str, __u32 str_size, const char *fmt, __u64 *data, __u32 data_len) = (void *) 165;
+
+/*
+ * bpf_sys_bpf
+ *
+ * 	Execute bpf syscall with given arguments.
+ *
+ * Returns
+ * 	A syscall result.
+ */
+static long (*bpf_sys_bpf)(__u32 cmd, void *attr, __u32 attr_size) = (void *) 166;
+
+/*
+ * bpf_btf_find_by_name_kind
+ *
+ * 	Find BTF type with given name and kind in vmlinux BTF or in module's BTFs.
+ *
+ * Returns
+ * 	Returns btf_id and btf_obj_fd in lower and upper 32 bits.
+ */
+static long (*bpf_btf_find_by_name_kind)(char *name, int name_sz, __u32 kind, int flags) = (void *) 167;
+
+/*
+ * bpf_sys_close
+ *
+ * 	Execute close syscall for given FD.
+ *
+ * Returns
+ * 	A syscall result.
+ */
+static long (*bpf_sys_close)(__u32 fd) = (void *) 168;
+
+/*
+ * bpf_timer_init
+ *
+ * 	Initialize the timer.
+ * 	First 4 bits of *flags* specify clockid.
+ * 	Only CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_BOOTTIME are allowed.
+ * 	All other bits of *flags* are reserved.
+ * 	The verifier will reject the program if *timer* is not from
+ * 	the same *map*.
+ *
+ * Returns
+ * 	0 on success.
+ * 	**-EBUSY** if *timer* is already initialized.
+ * 	**-EINVAL** if invalid *flags* are passed.
+ * 	**-EPERM** if *timer* is in a map that doesn't have any user references.
+ * 	The user space should either hold a file descriptor to a map with timers
+ * 	or pin such map in bpffs. When map is unpinned or file descriptor is
+ * 	closed all timers in the map will be cancelled and freed.
+ */
+static long (*bpf_timer_init)(struct bpf_timer *timer, void *map, __u64 flags) = (void *) 169;
+
+/*
+ * bpf_timer_set_callback
+ *
+ * 	Configure the timer to call *callback_fn* static function.
+ *
+ * Returns
+ * 	0 on success.
+ * 	**-EINVAL** if *timer* was not initialized with bpf_timer_init() earlier.
+ * 	**-EPERM** if *timer* is in a map that doesn't have any user references.
+ * 	The user space should either hold a file descriptor to a map with timers
+ * 	or pin such map in bpffs. When map is unpinned or file descriptor is
+ * 	closed all timers in the map will be cancelled and freed.
+ */
+static long (*bpf_timer_set_callback)(struct bpf_timer *timer, void *callback_fn) = (void *) 170;
+
+/*
+ * bpf_timer_start
+ *
+ * 	Set timer expiration N nanoseconds from the current time. The
+ * 	configured callback will be invoked in soft irq context on some cpu
+ * 	and will not repeat unless another bpf_timer_start() is made.
+ * 	In such case the next invocation can migrate to a different cpu.
+ * 	Since struct bpf_timer is a field inside map element the map
+ * 	owns the timer. The bpf_timer_set_callback() will increment refcnt
+ * 	of BPF program to make sure that callback_fn code stays valid.
+ * 	When user space reference to a map reaches zero all timers
+ * 	in a map are cancelled and corresponding program's refcnts are
+ * 	decremented. This is done to make sure that Ctrl-C of a user
+ * 	process doesn't leave any timers running. If map is pinned in
+ * 	bpffs the callback_fn can re-arm itself indefinitely.
+ * 	bpf_map_update/delete_elem() helpers and user space sys_bpf commands
+ * 	cancel and free the timer in the given map element.
+ * 	The map can contain timers that invoke callback_fn-s from different
+ * 	programs. The same callback_fn can serve different timers from
+ * 	different maps if key/value layout matches across maps.
+ * 	Every bpf_timer_set_callback() can have different callback_fn.
+ *
+ *
+ * Returns
+ * 	0 on success.
+ * 	**-EINVAL** if *timer* was not initialized with bpf_timer_init() earlier
+ * 	or invalid *flags* are passed.
+ */
+static long (*bpf_timer_start)(struct bpf_timer *timer, __u64 nsecs, __u64 flags) = (void *) 171;
+
+/*
+ * bpf_timer_cancel
+ *
+ * 	Cancel the timer and wait for callback_fn to finish if it was running.
+ *
+ * Returns
+ * 	0 if the timer was not active.
+ * 	1 if the timer was active.
+ * 	**-EINVAL** if *timer* was not initialized with bpf_timer_init() earlier.
+ * 	**-EDEADLK** if callback_fn tried to call bpf_timer_cancel() on its
+ * 	own timer which would have led to a deadlock otherwise.
+ */
+static long (*bpf_timer_cancel)(struct bpf_timer *timer) = (void *) 172;
+
+/*
+ * bpf_get_func_ip
+ *
+ * 	Get address of the traced function (for tracing and kprobe programs).
+ *
+ * Returns
+ * 	Address of the traced function.
+ * 	0 for kprobes placed within the function (not at the entry).
+ */
+static __u64 (*bpf_get_func_ip)(void *ctx) = (void *) 173;
+
+/*
+ * bpf_get_attach_cookie
+ *
+ * 	Get bpf_cookie value provided (optionally) during the program
+ * 	attachment. It might be different for each individual
+ * 	attachment, even if BPF program itself is the same.
+ * 	Expects BPF program context *ctx* as a first argument.
+ *
+ * 	Supported for the following program types:
+ * 		- kprobe/uprobe;
+ * 		- tracepoint;
+ * 		- perf_event.
+ *
+ * Returns
+ * 	Value specified by user at BPF link creation/attachment time
+ * 	or 0, if it was not specified.
+ */
+static __u64 (*bpf_get_attach_cookie)(void *ctx) = (void *) 174;
+
+/*
+ * bpf_task_pt_regs
+ *
+ * 	Get the struct pt_regs associated with **task**.
+ *
+ * Returns
+ * 	A pointer to struct pt_regs.
+ */
+static long (*bpf_task_pt_regs)(struct task_struct *task) = (void *) 175;
+
+/*
+ * bpf_get_branch_snapshot
+ *
+ * 	Get branch trace from hardware engines like Intel LBR. The
+ * 	hardware engine is stopped shortly after the helper is
+ * 	called. Therefore, the user need to filter branch entries
+ * 	based on the actual use case. To capture branch trace
+ * 	before the trigger point of the BPF program, the helper
+ * 	should be called at the beginning of the BPF program.
+ *
+ * 	The data is stored as struct perf_branch_entry into output
+ * 	buffer *entries*. *size* is the size of *entries* in bytes.
+ * 	*flags* is reserved for now and must be zero.
+ *
+ *
+ * Returns
+ * 	On success, number of bytes written to *buf*. On error, a
+ * 	negative value.
+ *
+ * 	**-EINVAL** if *flags* is not zero.
+ *
+ * 	**-ENOENT** if architecture does not support branch records.
+ */
+static long (*bpf_get_branch_snapshot)(void *entries, __u32 size, __u64 flags) = (void *) 176;
+
+/*
+ * bpf_trace_vprintk
+ *
+ * 	Behaves like **bpf_trace_printk**\ () helper, but takes an array of u64
+ * 	to format and can handle more format args as a result.
+ *
+ * 	Arguments are to be used as in **bpf_seq_printf**\ () helper.
+ *
+ * Returns
+ * 	The number of bytes written to the buffer, or a negative error
+ * 	in case of failure.
+ */
+static long (*bpf_trace_vprintk)(const char *fmt, __u32 fmt_size, const void *data, __u32 data_len) = (void *) 177;
+
+/*
+ * bpf_skc_to_unix_sock
+ *
+ * 	Dynamically cast a *sk* pointer to a *unix_sock* pointer.
+ *
+ * Returns
+ * 	*sk* if casting is valid, or **NULL** otherwise.
+ */
+static struct unix_sock *(*bpf_skc_to_unix_sock)(void *sk) = (void *) 178;
+
+/*
+ * bpf_kallsyms_lookup_name
+ *
+ * 	Get the address of a kernel symbol, returned in *res*. *res* is
+ * 	set to 0 if the symbol is not found.
+ *
+ * Returns
+ * 	On success, zero. On error, a negative value.
+ *
+ * 	**-EINVAL** if *flags* is not zero.
+ *
+ * 	**-EINVAL** if string *name* is not the same size as *name_sz*.
+ *
+ * 	**-ENOENT** if symbol is not found.
+ *
+ * 	**-EPERM** if caller does not have permission to obtain kernel address.
+ */
+static long (*bpf_kallsyms_lookup_name)(const char *name, int name_sz, int flags, __u64 *res) = (void *) 179;
+
+/*
+ * bpf_find_vma
+ *
+ * 	Find vma of *task* that contains *addr*, call *callback_fn*
+ * 	function with *task*, *vma*, and *callback_ctx*.
+ * 	The *callback_fn* should be a static function and
+ * 	the *callback_ctx* should be a pointer to the stack.
+ * 	The *flags* is used to control certain aspects of the helper.
+ * 	Currently, the *flags* must be 0.
+ *
+ * 	The expected callback signature is
+ *
+ * 	long (\*callback_fn)(struct task_struct \*task, struct vm_area_struct \*vma, void \*callback_ctx);
+ *
+ *
+ * Returns
+ * 	0 on success.
+ * 	**-ENOENT** if *task->mm* is NULL, or no vma contains *addr*.
+ * 	**-EBUSY** if failed to try lock mmap_lock.
+ * 	**-EINVAL** for invalid **flags**.
+ */
+static long (*bpf_find_vma)(struct task_struct *task, __u64 addr, void *callback_fn, void *callback_ctx, __u64 flags) = (void *) 180;
+
+/*
+ * bpf_loop
+ *
+ * 	For **nr_loops**, call **callback_fn** function
+ * 	with **callback_ctx** as the context parameter.
+ * 	The **callback_fn** should be a static function and
+ * 	the **callback_ctx** should be a pointer to the stack.
+ * 	The **flags** is used to control certain aspects of the helper.
+ * 	Currently, the **flags** must be 0. Currently, nr_loops is
+ * 	limited to 1 << 23 (~8 million) loops.
+ *
+ * 	long (\*callback_fn)(u32 index, void \*ctx);
+ *
+ * 	where **index** is the current index in the loop. The index
+ * 	is zero-indexed.
+ *
+ * 	If **callback_fn** returns 0, the helper will continue to the next
+ * 	loop. If return value is 1, the helper will skip the rest of
+ * 	the loops and return. Other return values are not used now,
+ * 	and will be rejected by the verifier.
+ *
+ *
+ * Returns
+ * 	The number of loops performed, **-EINVAL** for invalid **flags**,
+ * 	**-E2BIG** if **nr_loops** exceeds the maximum number of loops.
+ */
+static long (*bpf_loop)(__u32 nr_loops, void *callback_fn, void *callback_ctx, __u64 flags) = (void *) 181;
+
+/*
+ * bpf_strncmp
+ *
+ * 	Do strncmp() between **s1** and **s2**. **s1** doesn't need
+ * 	to be null-terminated and **s1_sz** is the maximum storage
+ * 	size of **s1**. **s2** must be a read-only string.
+ *
+ * Returns
+ * 	An integer less than, equal to, or greater than zero
+ * 	if the first **s1_sz** bytes of **s1** is found to be
+ * 	less than, to match, or be greater than **s2**.
+ */
+static long (*bpf_strncmp)(const char *s1, __u32 s1_sz, const char *s2) = (void *) 182;
+
+/*
+ * bpf_get_func_arg
+ *
+ * 	Get **n**-th argument register (zero based) of the traced function (for tracing programs)
+ * 	returned in **value**.
+ *
+ *
+ * Returns
+ * 	0 on success.
+ * 	**-EINVAL** if n >= argument register count of traced function.
+ */
+static long (*bpf_get_func_arg)(void *ctx, __u32 n, __u64 *value) = (void *) 183;
+
+/*
+ * bpf_get_func_ret
+ *
+ * 	Get return value of the traced function (for tracing programs)
+ * 	in **value**.
+ *
+ *
+ * Returns
+ * 	0 on success.
+ * 	**-EOPNOTSUPP** for tracing programs other than BPF_TRACE_FEXIT or BPF_MODIFY_RETURN.
+ */
+static long (*bpf_get_func_ret)(void *ctx, __u64 *value) = (void *) 184;
+
+/*
+ * bpf_get_func_arg_cnt
+ *
+ * 	Get number of registers of the traced function (for tracing programs) where
+ * 	function arguments are stored in these registers.
+ *
+ *
+ * Returns
+ * 	The number of argument registers of the traced function.
+ */
+static long (*bpf_get_func_arg_cnt)(void *ctx) = (void *) 185;
+
+/*
+ * bpf_get_retval
+ *
+ * 	Get the BPF program's return value that will be returned to the upper layers.
+ *
+ * 	This helper is currently supported by cgroup programs and only by the hooks
+ * 	where BPF program's return value is returned to the userspace via errno.
+ *
+ * Returns
+ * 	The BPF program's return value.
+ */
+static int (*bpf_get_retval)(void) = (void *) 186;
+
+/*
+ * bpf_set_retval
+ *
+ * 	Set the BPF program's return value that will be returned to the upper layers.
+ *
+ * 	This helper is currently supported by cgroup programs and only by the hooks
+ * 	where BPF program's return value is returned to the userspace via errno.
+ *
+ * 	Note that there is the following corner case where the program exports an error
+ * 	via bpf_set_retval but signals success via 'return 1':
+ *
+ * 		bpf_set_retval(-EPERM);
+ * 		return 1;
+ *
+ * 	In this case, the BPF program's return value will use helper's -EPERM. This
+ * 	still holds true for cgroup/bind{4,6} which supports extra 'return 3' success case.
+ *
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_set_retval)(int retval) = (void *) 187;
+
+/*
+ * bpf_xdp_get_buff_len
+ *
+ * 	Get the total size of a given xdp buff (linear and paged area)
+ *
+ * Returns
+ * 	The total size of a given xdp buffer.
+ */
+static __u64 (*bpf_xdp_get_buff_len)(struct xdp_md *xdp_md) = (void *) 188;
+
+/*
+ * bpf_xdp_load_bytes
+ *
+ * 	This helper is provided as an easy way to load data from a
+ * 	xdp buffer. It can be used to load *len* bytes from *offset* from
+ * 	the frame associated to *xdp_md*, into the buffer pointed by
+ * 	*buf*.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_xdp_load_bytes)(struct xdp_md *xdp_md, __u32 offset, void *buf, __u32 len) = (void *) 189;
+
+/*
+ * bpf_xdp_store_bytes
+ *
+ * 	Store *len* bytes from buffer *buf* into the frame
+ * 	associated to *xdp_md*, at *offset*.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_xdp_store_bytes)(struct xdp_md *xdp_md, __u32 offset, void *buf, __u32 len) = (void *) 190;
+
+/*
+ * bpf_copy_from_user_task
+ *
+ * 	Read *size* bytes from user space address *user_ptr* in *tsk*'s
+ * 	address space, and stores the data in *dst*. *flags* is not
+ * 	used yet and is provided for future extensibility. This helper
+ * 	can only be used by sleepable programs.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure. On error
+ * 	*dst* buffer is zeroed out.
+ */
+static long (*bpf_copy_from_user_task)(void *dst, __u32 size, const void *user_ptr, struct task_struct *tsk, __u64 flags) = (void *) 191;
+
+/*
+ * bpf_skb_set_tstamp
+ *
+ * 	Change the __sk_buff->tstamp_type to *tstamp_type*
+ * 	and set *tstamp* to the __sk_buff->tstamp together.
+ *
+ * 	If there is no need to change the __sk_buff->tstamp_type,
+ * 	the tstamp value can be directly written to __sk_buff->tstamp
+ * 	instead.
+ *
+ * 	BPF_SKB_TSTAMP_DELIVERY_MONO is the only tstamp that
+ * 	will be kept during bpf_redirect_*().  A non zero
+ * 	*tstamp* must be used with the BPF_SKB_TSTAMP_DELIVERY_MONO
+ * 	*tstamp_type*.
+ *
+ * 	A BPF_SKB_TSTAMP_UNSPEC *tstamp_type* can only be used
+ * 	with a zero *tstamp*.
+ *
+ * 	Only IPv4 and IPv6 skb->protocol are supported.
+ *
+ * 	This function is most useful when it needs to set a
+ * 	mono delivery time to __sk_buff->tstamp and then
+ * 	bpf_redirect_*() to the egress of an iface.  For example,
+ * 	changing the (rcv) timestamp in __sk_buff->tstamp at
+ * 	ingress to a mono delivery time and then bpf_redirect_*()
+ * 	to sch_fq@phy-dev.
+ *
+ * Returns
+ * 	0 on success.
+ * 	**-EINVAL** for invalid input
+ * 	**-EOPNOTSUPP** for unsupported protocol
+ */
+static long (*bpf_skb_set_tstamp)(struct __sk_buff *skb, __u64 tstamp, __u32 tstamp_type) = (void *) 192;
+
+/*
+ * bpf_ima_file_hash
+ *
+ * 	Returns a calculated IMA hash of the *file*.
+ * 	If the hash is larger than *size*, then only *size*
+ * 	bytes will be copied to *dst*
+ *
+ * Returns
+ * 	The **hash_algo** is returned on success,
+ * 	**-EOPNOTSUP** if the hash calculation failed or **-EINVAL** if
+ * 	invalid arguments are passed.
+ */
+static long (*bpf_ima_file_hash)(struct file *file, void *dst, __u32 size) = (void *) 193;
+
+/*
+ * bpf_kptr_xchg
+ *
+ * 	Exchange kptr at pointer *map_value* with *ptr*, and return the
+ * 	old value. *ptr* can be NULL, otherwise it must be a referenced
+ * 	pointer which will be released when this helper is called.
+ *
+ * Returns
+ * 	The old value of kptr (which can be NULL). The returned pointer
+ * 	if not NULL, is a reference which must be released using its
+ * 	corresponding release function, or moved into a BPF map before
+ * 	program exit.
+ */
+static void *(*bpf_kptr_xchg)(void *map_value, void *ptr) = (void *) 194;
+
+/*
+ * bpf_map_lookup_percpu_elem
+ *
+ * 	Perform a lookup in *percpu map* for an entry associated to
+ * 	*key* on *cpu*.
+ *
+ * Returns
+ * 	Map value associated to *key* on *cpu*, or **NULL** if no entry
+ * 	was found or *cpu* is invalid.
+ */
+static void *(*bpf_map_lookup_percpu_elem)(void *map, const void *key, __u32 cpu) = (void *) 195;
+
+/*
+ * bpf_skc_to_mptcp_sock
+ *
+ * 	Dynamically cast a *sk* pointer to a *mptcp_sock* pointer.
+ *
+ * Returns
+ * 	*sk* if casting is valid, or **NULL** otherwise.
+ */
+static struct mptcp_sock *(*bpf_skc_to_mptcp_sock)(void *sk) = (void *) 196;
+
+/*
+ * bpf_dynptr_from_mem
+ *
+ * 	Get a dynptr to local memory *data*.
+ *
+ * 	*data* must be a ptr to a map value.
+ * 	The maximum *size* supported is DYNPTR_MAX_SIZE.
+ * 	*flags* is currently unused.
+ *
+ * Returns
+ * 	0 on success, -E2BIG if the size exceeds DYNPTR_MAX_SIZE,
+ * 	-EINVAL if flags is not 0.
+ */
+static long (*bpf_dynptr_from_mem)(void *data, __u32 size, __u64 flags, struct bpf_dynptr *ptr) = (void *) 197;
+
+/*
+ * bpf_ringbuf_reserve_dynptr
+ *
+ * 	Reserve *size* bytes of payload in a ring buffer *ringbuf*
+ * 	through the dynptr interface. *flags* must be 0.
+ *
+ * 	Please note that a corresponding bpf_ringbuf_submit_dynptr or
+ * 	bpf_ringbuf_discard_dynptr must be called on *ptr*, even if the
+ * 	reservation fails. This is enforced by the verifier.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static long (*bpf_ringbuf_reserve_dynptr)(void *ringbuf, __u32 size, __u64 flags, struct bpf_dynptr *ptr) = (void *) 198;
+
+/*
+ * bpf_ringbuf_submit_dynptr
+ *
+ * 	Submit reserved ring buffer sample, pointed to by *data*,
+ * 	through the dynptr interface. This is a no-op if the dynptr is
+ * 	invalid/null.
+ *
+ * 	For more information on *flags*, please see
+ * 	'bpf_ringbuf_submit'.
+ *
+ * Returns
+ * 	Nothing. Always succeeds.
+ */
+static void (*bpf_ringbuf_submit_dynptr)(struct bpf_dynptr *ptr, __u64 flags) = (void *) 199;
+
+/*
+ * bpf_ringbuf_discard_dynptr
+ *
+ * 	Discard reserved ring buffer sample through the dynptr
+ * 	interface. This is a no-op if the dynptr is invalid/null.
+ *
+ * 	For more information on *flags*, please see
+ * 	'bpf_ringbuf_discard'.
+ *
+ * Returns
+ * 	Nothing. Always succeeds.
+ */
+static void (*bpf_ringbuf_discard_dynptr)(struct bpf_dynptr *ptr, __u64 flags) = (void *) 200;
+
+/*
+ * bpf_dynptr_read
+ *
+ * 	Read *len* bytes from *src* into *dst*, starting from *offset*
+ * 	into *src*.
+ * 	*flags* is currently unused.
+ *
+ * Returns
+ * 	0 on success, -E2BIG if *offset* + *len* exceeds the length
+ * 	of *src*'s data, -EINVAL if *src* is an invalid dynptr or if
+ * 	*flags* is not 0.
+ */
+static long (*bpf_dynptr_read)(void *dst, __u32 len, const struct bpf_dynptr *src, __u32 offset, __u64 flags) = (void *) 201;
+
+/*
+ * bpf_dynptr_write
+ *
+ * 	Write *len* bytes from *src* into *dst*, starting from *offset*
+ * 	into *dst*.
+ * 	*flags* is currently unused.
+ *
+ * Returns
+ * 	0 on success, -E2BIG if *offset* + *len* exceeds the length
+ * 	of *dst*'s data, -EINVAL if *dst* is an invalid dynptr or if *dst*
+ * 	is a read-only dynptr or if *flags* is not 0.
+ */
+static long (*bpf_dynptr_write)(const struct bpf_dynptr *dst, __u32 offset, void *src, __u32 len, __u64 flags) = (void *) 202;
+
+/*
+ * bpf_dynptr_data
+ *
+ * 	Get a pointer to the underlying dynptr data.
+ *
+ * 	*len* must be a statically known value. The returned data slice
+ * 	is invalidated whenever the dynptr is invalidated.
+ *
+ * Returns
+ * 	Pointer to the underlying dynptr data, NULL if the dynptr is
+ * 	read-only, if the dynptr is invalid, or if the offset and length
+ * 	is out of bounds.
+ */
+static void *(*bpf_dynptr_data)(const struct bpf_dynptr *ptr, __u32 offset, __u32 len) = (void *) 203;
+
+/*
+ * bpf_tcp_raw_gen_syncookie_ipv4
+ *
+ * 	Try to issue a SYN cookie for the packet with corresponding
+ * 	IPv4/TCP headers, *iph* and *th*, without depending on a
+ * 	listening socket.
+ *
+ * 	*iph* points to the IPv4 header.
+ *
+ * 	*th* points to the start of the TCP header, while *th_len*
+ * 	contains the length of the TCP header (at least
+ * 	**sizeof**\ (**struct tcphdr**)).
+ *
+ * Returns
+ * 	On success, lower 32 bits hold the generated SYN cookie in
+ * 	followed by 16 bits which hold the MSS value for that cookie,
+ * 	and the top 16 bits are unused.
+ *
+ * 	On failure, the returned value is one of the following:
+ *
+ * 	**-EINVAL** if *th_len* is invalid.
+ */
+static __s64 (*bpf_tcp_raw_gen_syncookie_ipv4)(struct iphdr *iph, struct tcphdr *th, __u32 th_len) = (void *) 204;
+
+/*
+ * bpf_tcp_raw_gen_syncookie_ipv6
+ *
+ * 	Try to issue a SYN cookie for the packet with corresponding
+ * 	IPv6/TCP headers, *iph* and *th*, without depending on a
+ * 	listening socket.
+ *
+ * 	*iph* points to the IPv6 header.
+ *
+ * 	*th* points to the start of the TCP header, while *th_len*
+ * 	contains the length of the TCP header (at least
+ * 	**sizeof**\ (**struct tcphdr**)).
+ *
+ * Returns
+ * 	On success, lower 32 bits hold the generated SYN cookie in
+ * 	followed by 16 bits which hold the MSS value for that cookie,
+ * 	and the top 16 bits are unused.
+ *
+ * 	On failure, the returned value is one of the following:
+ *
+ * 	**-EINVAL** if *th_len* is invalid.
+ *
+ * 	**-EPROTONOSUPPORT** if CONFIG_IPV6 is not builtin.
+ */
+static __s64 (*bpf_tcp_raw_gen_syncookie_ipv6)(struct ipv6hdr *iph, struct tcphdr *th, __u32 th_len) = (void *) 205;
+
+/*
+ * bpf_tcp_raw_check_syncookie_ipv4
+ *
+ * 	Check whether *iph* and *th* contain a valid SYN cookie ACK
+ * 	without depending on a listening socket.
+ *
+ * 	*iph* points to the IPv4 header.
+ *
+ * 	*th* points to the TCP header.
+ *
+ * Returns
+ * 	0 if *iph* and *th* are a valid SYN cookie ACK.
+ *
+ * 	On failure, the returned value is one of the following:
+ *
+ * 	**-EACCES** if the SYN cookie is not valid.
+ */
+static long (*bpf_tcp_raw_check_syncookie_ipv4)(struct iphdr *iph, struct tcphdr *th) = (void *) 206;
+
+/*
+ * bpf_tcp_raw_check_syncookie_ipv6
+ *
+ * 	Check whether *iph* and *th* contain a valid SYN cookie ACK
+ * 	without depending on a listening socket.
+ *
+ * 	*iph* points to the IPv6 header.
+ *
+ * 	*th* points to the TCP header.
+ *
+ * Returns
+ * 	0 if *iph* and *th* are a valid SYN cookie ACK.
+ *
+ * 	On failure, the returned value is one of the following:
+ *
+ * 	**-EACCES** if the SYN cookie is not valid.
+ *
+ * 	**-EPROTONOSUPPORT** if CONFIG_IPV6 is not builtin.
+ */
+static long (*bpf_tcp_raw_check_syncookie_ipv6)(struct ipv6hdr *iph, struct tcphdr *th) = (void *) 207;
+
+/*
+ * bpf_ktime_get_tai_ns
+ *
+ * 	A nonsettable system-wide clock derived from wall-clock time but
+ * 	ignoring leap seconds.  This clock does not experience
+ * 	discontinuities and backwards jumps caused by NTP inserting leap
+ * 	seconds as CLOCK_REALTIME does.
+ *
+ * 	See: **clock_gettime**\ (**CLOCK_TAI**)
+ *
+ * Returns
+ * 	Current *ktime*.
+ */
+static __u64 (*bpf_ktime_get_tai_ns)(void) = (void *) 208;
+
+/*
+ * bpf_user_ringbuf_drain
+ *
+ * 	Drain samples from the specified user ring buffer, and invoke
+ * 	the provided callback for each such sample:
+ *
+ * 	long (\*callback_fn)(const struct bpf_dynptr \*dynptr, void \*ctx);
+ *
+ * 	If **callback_fn** returns 0, the helper will continue to try
+ * 	and drain the next sample, up to a maximum of
+ * 	BPF_MAX_USER_RINGBUF_SAMPLES samples. If the return value is 1,
+ * 	the helper will skip the rest of the samples and return. Other
+ * 	return values are not used now, and will be rejected by the
+ * 	verifier.
+ *
+ * Returns
+ * 	The number of drained samples if no error was encountered while
+ * 	draining samples, or 0 if no samples were present in the ring
+ * 	buffer. If a user-space producer was epoll-waiting on this map,
+ * 	and at least one sample was drained, they will receive an event
+ * 	notification notifying them of available space in the ring
+ * 	buffer. If the BPF_RB_NO_WAKEUP flag is passed to this
+ * 	function, no wakeup notification will be sent. If the
+ * 	BPF_RB_FORCE_WAKEUP flag is passed, a wakeup notification will
+ * 	be sent even if no sample was drained.
+ *
+ * 	On failure, the returned value is one of the following:
+ *
+ * 	**-EBUSY** if the ring buffer is contended, and another calling
+ * 	context was concurrently draining the ring buffer.
+ *
+ * 	**-EINVAL** if user-space is not properly tracking the ring
+ * 	buffer due to the producer position not being aligned to 8
+ * 	bytes, a sample not being aligned to 8 bytes, or the producer
+ * 	position not matching the advertised length of a sample.
+ *
+ * 	**-E2BIG** if user-space has tried to publish a sample which is
+ * 	larger than the size of the ring buffer, or which cannot fit
+ * 	within a struct bpf_dynptr.
+ */
+static long (*bpf_user_ringbuf_drain)(void *map, void *callback_fn, void *ctx, __u64 flags) = (void *) 209;
+
+/*
+ * bpf_cgrp_storage_get
+ *
+ * 	Get a bpf_local_storage from the *cgroup*.
+ *
+ * 	Logically, it could be thought of as getting the value from
+ * 	a *map* with *cgroup* as the **key**.  From this
+ * 	perspective,  the usage is not much different from
+ * 	**bpf_map_lookup_elem**\ (*map*, **&**\ *cgroup*) except this
+ * 	helper enforces the key must be a cgroup struct and the map must also
+ * 	be a **BPF_MAP_TYPE_CGRP_STORAGE**.
+ *
+ * 	In reality, the local-storage value is embedded directly inside of the
+ * 	*cgroup* object itself, rather than being located in the
+ * 	**BPF_MAP_TYPE_CGRP_STORAGE** map. When the local-storage value is
+ * 	queried for some *map* on a *cgroup* object, the kernel will perform an
+ * 	O(n) iteration over all of the live local-storage values for that
+ * 	*cgroup* object until the local-storage value for the *map* is found.
+ *
+ * 	An optional *flags* (**BPF_LOCAL_STORAGE_GET_F_CREATE**) can be
+ * 	used such that a new bpf_local_storage will be
+ * 	created if one does not exist.  *value* can be used
+ * 	together with **BPF_LOCAL_STORAGE_GET_F_CREATE** to specify
+ * 	the initial value of a bpf_local_storage.  If *value* is
+ * 	**NULL**, the new bpf_local_storage will be zero initialized.
+ *
+ * Returns
+ * 	A bpf_local_storage pointer is returned on success.
+ *
+ * 	**NULL** if not found or there was an error in adding
+ * 	a new bpf_local_storage.
+ */
+static void *(*bpf_cgrp_storage_get)(void *map, struct cgroup *cgroup, void *value, __u64 flags) = (void *) 210;
+
+/*
+ * bpf_cgrp_storage_delete
+ *
+ * 	Delete a bpf_local_storage from a *cgroup*.
+ *
+ * Returns
+ * 	0 on success.
+ *
+ * 	**-ENOENT** if the bpf_local_storage cannot be found.
+ */
+static long (*bpf_cgrp_storage_delete)(void *map, struct cgroup *cgroup) = (void *) 211;
+
+
diff --git a/src/bpf_helpers.h b/src/bpf_helpers.h
new file mode 100644
index 0000000..d37c4fe
--- /dev/null
+++ b/src/bpf_helpers.h
@@ -0,0 +1,289 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __BPF_HELPERS__
+#define __BPF_HELPERS__
+
+/*
+ * Note that bpf programs need to include either
+ * vmlinux.h (auto-generated from BTF) or linux/types.h
+ * in advance since bpf_helper_defs.h uses such types
+ * as __u64.
+ */
+#include "bpf_helper_defs.h"
+
+#define __uint(name, val) int (*name)[val]
+#define __type(name, val) typeof(val) *name
+#define __array(name, val) typeof(val) *name[]
+
+/*
+ * Helper macro to place programs, maps, license in
+ * different sections in elf_bpf file. Section names
+ * are interpreted by libbpf depending on the context (BPF programs, BPF maps,
+ * extern variables, etc).
+ * To allow use of SEC() with externs (e.g., for extern .maps declarations),
+ * make sure __attribute__((unused)) doesn't trigger compilation warning.
+ */
+#if __GNUC__ && !__clang__
+
+/*
+ * Pragma macros are broken on GCC
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55578
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400
+ */
+#define SEC(name) __attribute__((section(name), used))
+
+#else
+
+#define SEC(name) \
+	_Pragma("GCC diagnostic push")					    \
+	_Pragma("GCC diagnostic ignored \"-Wignored-attributes\"")	    \
+	__attribute__((section(name), used))				    \
+	_Pragma("GCC diagnostic pop")					    \
+
+#endif
+
+/* Avoid 'linux/stddef.h' definition of '__always_inline'. */
+#undef __always_inline
+#define __always_inline inline __attribute__((always_inline))
+
+#ifndef __noinline
+#define __noinline __attribute__((noinline))
+#endif
+#ifndef __weak
+#define __weak __attribute__((weak))
+#endif
+
+/*
+ * Use __hidden attribute to mark a non-static BPF subprogram effectively
+ * static for BPF verifier's verification algorithm purposes, allowing more
+ * extensive and permissive BPF verification process, taking into account
+ * subprogram's caller context.
+ */
+#define __hidden __attribute__((visibility("hidden")))
+
+/* When utilizing vmlinux.h with BPF CO-RE, user BPF programs can't include
+ * any system-level headers (such as stddef.h, linux/version.h, etc), and
+ * commonly-used macros like NULL and KERNEL_VERSION aren't available through
+ * vmlinux.h. This just adds unnecessary hurdles and forces users to re-define
+ * them on their own. So as a convenience, provide such definitions here.
+ */
+#ifndef NULL
+#define NULL ((void *)0)
+#endif
+
+#ifndef KERNEL_VERSION
+#define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c)))
+#endif
+
+/*
+ * Helper macros to manipulate data structures
+ */
+#ifndef offsetof
+#define offsetof(TYPE, MEMBER)	((unsigned long)&((TYPE *)0)->MEMBER)
+#endif
+#ifndef container_of
+#define container_of(ptr, type, member)				\
+	({							\
+		void *__mptr = (void *)(ptr);			\
+		((type *)(__mptr - offsetof(type, member)));	\
+	})
+#endif
+
+/*
+ * Compiler (optimization) barrier.
+ */
+#ifndef barrier
+#define barrier() asm volatile("" ::: "memory")
+#endif
+
+/* Variable-specific compiler (optimization) barrier. It's a no-op which makes
+ * compiler believe that there is some black box modification of a given
+ * variable and thus prevents compiler from making extra assumption about its
+ * value and potential simplifications and optimizations on this variable.
+ *
+ * E.g., compiler might often delay or even omit 32-bit to 64-bit casting of
+ * a variable, making some code patterns unverifiable. Putting barrier_var()
+ * in place will ensure that cast is performed before the barrier_var()
+ * invocation, because compiler has to pessimistically assume that embedded
+ * asm section might perform some extra operations on that variable.
+ *
+ * This is a variable-specific variant of more global barrier().
+ */
+#ifndef barrier_var
+#define barrier_var(var) asm volatile("" : "=r"(var) : "0"(var))
+#endif
+
+/*
+ * Helper macro to throw a compilation error if __bpf_unreachable() gets
+ * built into the resulting code. This works given BPF back end does not
+ * implement __builtin_trap(). This is useful to assert that certain paths
+ * of the program code are never used and hence eliminated by the compiler.
+ *
+ * For example, consider a switch statement that covers known cases used by
+ * the program. __bpf_unreachable() can then reside in the default case. If
+ * the program gets extended such that a case is not covered in the switch
+ * statement, then it will throw a build error due to the default case not
+ * being compiled out.
+ */
+#ifndef __bpf_unreachable
+# define __bpf_unreachable()	__builtin_trap()
+#endif
+
+/*
+ * Helper function to perform a tail call with a constant/immediate map slot.
+ */
+#if __clang_major__ >= 8 && defined(__bpf__)
+static __always_inline void
+bpf_tail_call_static(void *ctx, const void *map, const __u32 slot)
+{
+	if (!__builtin_constant_p(slot))
+		__bpf_unreachable();
+
+	/*
+	 * Provide a hard guarantee that LLVM won't optimize setting r2 (map
+	 * pointer) and r3 (constant map index) from _different paths_ ending
+	 * up at the _same_ call insn as otherwise we won't be able to use the
+	 * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel
+	 * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key
+	 * tracking for prog array pokes") for details on verifier tracking.
+	 *
+	 * Note on clobber list: we need to stay in-line with BPF calling
+	 * convention, so even if we don't end up using r0, r4, r5, we need
+	 * to mark them as clobber so that LLVM doesn't end up using them
+	 * before / after the call.
+	 */
+	asm volatile("r1 = %[ctx]\n\t"
+		     "r2 = %[map]\n\t"
+		     "r3 = %[slot]\n\t"
+		     "call 12"
+		     :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot)
+		     : "r0", "r1", "r2", "r3", "r4", "r5");
+}
+#endif
+
+enum libbpf_pin_type {
+	LIBBPF_PIN_NONE,
+	/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
+	LIBBPF_PIN_BY_NAME,
+};
+
+enum libbpf_tristate {
+	TRI_NO = 0,
+	TRI_YES = 1,
+	TRI_MODULE = 2,
+};
+
+#define __kconfig __attribute__((section(".kconfig")))
+#define __ksym __attribute__((section(".ksyms")))
+#define __kptr __attribute__((btf_type_tag("kptr")))
+#define __kptr_ref __attribute__((btf_type_tag("kptr_ref")))
+
+#ifndef ___bpf_concat
+#define ___bpf_concat(a, b) a ## b
+#endif
+#ifndef ___bpf_apply
+#define ___bpf_apply(fn, n) ___bpf_concat(fn, n)
+#endif
+#ifndef ___bpf_nth
+#define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N
+#endif
+#ifndef ___bpf_narg
+#define ___bpf_narg(...) \
+	___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
+#endif
+
+#define ___bpf_fill0(arr, p, x) do {} while (0)
+#define ___bpf_fill1(arr, p, x) arr[p] = x
+#define ___bpf_fill2(arr, p, x, args...) arr[p] = x; ___bpf_fill1(arr, p + 1, args)
+#define ___bpf_fill3(arr, p, x, args...) arr[p] = x; ___bpf_fill2(arr, p + 1, args)
+#define ___bpf_fill4(arr, p, x, args...) arr[p] = x; ___bpf_fill3(arr, p + 1, args)
+#define ___bpf_fill5(arr, p, x, args...) arr[p] = x; ___bpf_fill4(arr, p + 1, args)
+#define ___bpf_fill6(arr, p, x, args...) arr[p] = x; ___bpf_fill5(arr, p + 1, args)
+#define ___bpf_fill7(arr, p, x, args...) arr[p] = x; ___bpf_fill6(arr, p + 1, args)
+#define ___bpf_fill8(arr, p, x, args...) arr[p] = x; ___bpf_fill7(arr, p + 1, args)
+#define ___bpf_fill9(arr, p, x, args...) arr[p] = x; ___bpf_fill8(arr, p + 1, args)
+#define ___bpf_fill10(arr, p, x, args...) arr[p] = x; ___bpf_fill9(arr, p + 1, args)
+#define ___bpf_fill11(arr, p, x, args...) arr[p] = x; ___bpf_fill10(arr, p + 1, args)
+#define ___bpf_fill12(arr, p, x, args...) arr[p] = x; ___bpf_fill11(arr, p + 1, args)
+#define ___bpf_fill(arr, args...) \
+	___bpf_apply(___bpf_fill, ___bpf_narg(args))(arr, 0, args)
+
+/*
+ * BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values
+ * in a structure.
+ */
+#define BPF_SEQ_PRINTF(seq, fmt, args...)			\
+({								\
+	static const char ___fmt[] = fmt;			\
+	unsigned long long ___param[___bpf_narg(args)];		\
+								\
+	_Pragma("GCC diagnostic push")				\
+	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")	\
+	___bpf_fill(___param, args);				\
+	_Pragma("GCC diagnostic pop")				\
+								\
+	bpf_seq_printf(seq, ___fmt, sizeof(___fmt),		\
+		       ___param, sizeof(___param));		\
+})
+
+/*
+ * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of
+ * an array of u64.
+ */
+#define BPF_SNPRINTF(out, out_size, fmt, args...)		\
+({								\
+	static const char ___fmt[] = fmt;			\
+	unsigned long long ___param[___bpf_narg(args)];		\
+								\
+	_Pragma("GCC diagnostic push")				\
+	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")	\
+	___bpf_fill(___param, args);				\
+	_Pragma("GCC diagnostic pop")				\
+								\
+	bpf_snprintf(out, out_size, ___fmt,			\
+		     ___param, sizeof(___param));		\
+})
+
+#ifdef BPF_NO_GLOBAL_DATA
+#define BPF_PRINTK_FMT_MOD
+#else
+#define BPF_PRINTK_FMT_MOD static const
+#endif
+
+#define __bpf_printk(fmt, ...)				\
+({							\
+	BPF_PRINTK_FMT_MOD char ____fmt[] = fmt;	\
+	bpf_trace_printk(____fmt, sizeof(____fmt),	\
+			 ##__VA_ARGS__);		\
+})
+
+/*
+ * __bpf_vprintk wraps the bpf_trace_vprintk helper with variadic arguments
+ * instead of an array of u64.
+ */
+#define __bpf_vprintk(fmt, args...)				\
+({								\
+	static const char ___fmt[] = fmt;			\
+	unsigned long long ___param[___bpf_narg(args)];		\
+								\
+	_Pragma("GCC diagnostic push")				\
+	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")	\
+	___bpf_fill(___param, args);				\
+	_Pragma("GCC diagnostic pop")				\
+								\
+	bpf_trace_vprintk(___fmt, sizeof(___fmt),		\
+			  ___param, sizeof(___param));		\
+})
+
+/* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args
+ * Otherwise use __bpf_vprintk
+ */
+#define ___bpf_pick_printk(...) \
+	___bpf_nth(_, ##__VA_ARGS__, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk,	\
+		   __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk,		\
+		   __bpf_vprintk, __bpf_vprintk, __bpf_printk /*3*/, __bpf_printk /*2*/,\
+		   __bpf_printk /*1*/, __bpf_printk /*0*/)
+
+/* Helper macro to print out debug messages */
+#define bpf_printk(fmt, args...) ___bpf_pick_printk(args)(fmt, ##args)
+
+#endif
diff --git a/src/bpf_prog_linfo.c b/src/bpf_prog_linfo.c
new file mode 100644
index 0000000..5c50309
--- /dev/null
+++ b/src/bpf_prog_linfo.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2018 Facebook */
+
+#include <string.h>
+#include <stdlib.h>
+#include <linux/err.h>
+#include <linux/bpf.h>
+#include "libbpf.h"
+#include "libbpf_internal.h"
+
+struct bpf_prog_linfo {
+	void *raw_linfo;
+	void *raw_jited_linfo;
+	__u32 *nr_jited_linfo_per_func;
+	__u32 *jited_linfo_func_idx;
+	__u32 nr_linfo;
+	__u32 nr_jited_func;
+	__u32 rec_size;
+	__u32 jited_rec_size;
+};
+
+static int dissect_jited_func(struct bpf_prog_linfo *prog_linfo,
+			      const __u64 *ksym_func, const __u32 *ksym_len)
+{
+	__u32 nr_jited_func, nr_linfo;
+	const void *raw_jited_linfo;
+	const __u64 *jited_linfo;
+	__u64 last_jited_linfo;
+	/*
+	 * Index to raw_jited_linfo:
+	 *      i: Index for searching the next ksym_func
+	 * prev_i: Index to the last found ksym_func
+	 */
+	__u32 i, prev_i;
+	__u32 f; /* Index to ksym_func */
+
+	raw_jited_linfo = prog_linfo->raw_jited_linfo;
+	jited_linfo = raw_jited_linfo;
+	if (ksym_func[0] != *jited_linfo)
+		goto errout;
+
+	prog_linfo->jited_linfo_func_idx[0] = 0;
+	nr_jited_func = prog_linfo->nr_jited_func;
+	nr_linfo = prog_linfo->nr_linfo;
+
+	for (prev_i = 0, i = 1, f = 1;
+	     i < nr_linfo && f < nr_jited_func;
+	     i++) {
+		raw_jited_linfo += prog_linfo->jited_rec_size;
+		last_jited_linfo = *jited_linfo;
+		jited_linfo = raw_jited_linfo;
+
+		if (ksym_func[f] == *jited_linfo) {
+			prog_linfo->jited_linfo_func_idx[f] = i;
+
+			/* Sanity check */
+			if (last_jited_linfo - ksym_func[f - 1] + 1 >
+			    ksym_len[f - 1])
+				goto errout;
+
+			prog_linfo->nr_jited_linfo_per_func[f - 1] =
+				i - prev_i;
+			prev_i = i;
+
+			/*
+			 * The ksym_func[f] is found in jited_linfo.
+			 * Look for the next one.
+			 */
+			f++;
+		} else if (*jited_linfo <= last_jited_linfo) {
+			/* Ensure the addr is increasing _within_ a func */
+			goto errout;
+		}
+	}
+
+	if (f != nr_jited_func)
+		goto errout;
+
+	prog_linfo->nr_jited_linfo_per_func[nr_jited_func - 1] =
+		nr_linfo - prev_i;
+
+	return 0;
+
+errout:
+	return -EINVAL;
+}
+
+void bpf_prog_linfo__free(struct bpf_prog_linfo *prog_linfo)
+{
+	if (!prog_linfo)
+		return;
+
+	free(prog_linfo->raw_linfo);
+	free(prog_linfo->raw_jited_linfo);
+	free(prog_linfo->nr_jited_linfo_per_func);
+	free(prog_linfo->jited_linfo_func_idx);
+	free(prog_linfo);
+}
+
+struct bpf_prog_linfo *bpf_prog_linfo__new(const struct bpf_prog_info *info)
+{
+	struct bpf_prog_linfo *prog_linfo;
+	__u32 nr_linfo, nr_jited_func;
+	__u64 data_sz;
+
+	nr_linfo = info->nr_line_info;
+
+	if (!nr_linfo)
+		return errno = EINVAL, NULL;
+
+	/*
+	 * The min size that bpf_prog_linfo has to access for
+	 * searching purpose.
+	 */
+	if (info->line_info_rec_size <
+	    offsetof(struct bpf_line_info, file_name_off))
+		return errno = EINVAL, NULL;
+
+	prog_linfo = calloc(1, sizeof(*prog_linfo));
+	if (!prog_linfo)
+		return errno = ENOMEM, NULL;
+
+	/* Copy xlated line_info */
+	prog_linfo->nr_linfo = nr_linfo;
+	prog_linfo->rec_size = info->line_info_rec_size;
+	data_sz = (__u64)nr_linfo * prog_linfo->rec_size;
+	prog_linfo->raw_linfo = malloc(data_sz);
+	if (!prog_linfo->raw_linfo)
+		goto err_free;
+	memcpy(prog_linfo->raw_linfo, (void *)(long)info->line_info, data_sz);
+
+	nr_jited_func = info->nr_jited_ksyms;
+	if (!nr_jited_func ||
+	    !info->jited_line_info ||
+	    info->nr_jited_line_info != nr_linfo ||
+	    info->jited_line_info_rec_size < sizeof(__u64) ||
+	    info->nr_jited_func_lens != nr_jited_func ||
+	    !info->jited_ksyms ||
+	    !info->jited_func_lens)
+		/* Not enough info to provide jited_line_info */
+		return prog_linfo;
+
+	/* Copy jited_line_info */
+	prog_linfo->nr_jited_func = nr_jited_func;
+	prog_linfo->jited_rec_size = info->jited_line_info_rec_size;
+	data_sz = (__u64)nr_linfo * prog_linfo->jited_rec_size;
+	prog_linfo->raw_jited_linfo = malloc(data_sz);
+	if (!prog_linfo->raw_jited_linfo)
+		goto err_free;
+	memcpy(prog_linfo->raw_jited_linfo,
+	       (void *)(long)info->jited_line_info, data_sz);
+
+	/* Number of jited_line_info per jited func */
+	prog_linfo->nr_jited_linfo_per_func = malloc(nr_jited_func *
+						     sizeof(__u32));
+	if (!prog_linfo->nr_jited_linfo_per_func)
+		goto err_free;
+
+	/*
+	 * For each jited func,
+	 * the start idx to the "linfo" and "jited_linfo" array,
+	 */
+	prog_linfo->jited_linfo_func_idx = malloc(nr_jited_func *
+						  sizeof(__u32));
+	if (!prog_linfo->jited_linfo_func_idx)
+		goto err_free;
+
+	if (dissect_jited_func(prog_linfo,
+			       (__u64 *)(long)info->jited_ksyms,
+			       (__u32 *)(long)info->jited_func_lens))
+		goto err_free;
+
+	return prog_linfo;
+
+err_free:
+	bpf_prog_linfo__free(prog_linfo);
+	return errno = EINVAL, NULL;
+}
+
+const struct bpf_line_info *
+bpf_prog_linfo__lfind_addr_func(const struct bpf_prog_linfo *prog_linfo,
+				__u64 addr, __u32 func_idx, __u32 nr_skip)
+{
+	__u32 jited_rec_size, rec_size, nr_linfo, start, i;
+	const void *raw_jited_linfo, *raw_linfo;
+	const __u64 *jited_linfo;
+
+	if (func_idx >= prog_linfo->nr_jited_func)
+		return errno = ENOENT, NULL;
+
+	nr_linfo = prog_linfo->nr_jited_linfo_per_func[func_idx];
+	if (nr_skip >= nr_linfo)
+		return errno = ENOENT, NULL;
+
+	start = prog_linfo->jited_linfo_func_idx[func_idx] + nr_skip;
+	jited_rec_size = prog_linfo->jited_rec_size;
+	raw_jited_linfo = prog_linfo->raw_jited_linfo +
+		(start * jited_rec_size);
+	jited_linfo = raw_jited_linfo;
+	if (addr < *jited_linfo)
+		return errno = ENOENT, NULL;
+
+	nr_linfo -= nr_skip;
+	rec_size = prog_linfo->rec_size;
+	raw_linfo = prog_linfo->raw_linfo + (start * rec_size);
+	for (i = 0; i < nr_linfo; i++) {
+		if (addr < *jited_linfo)
+			break;
+
+		raw_linfo += rec_size;
+		raw_jited_linfo += jited_rec_size;
+		jited_linfo = raw_jited_linfo;
+	}
+
+	return raw_linfo - rec_size;
+}
+
+const struct bpf_line_info *
+bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
+		      __u32 insn_off, __u32 nr_skip)
+{
+	const struct bpf_line_info *linfo;
+	__u32 rec_size, nr_linfo, i;
+	const void *raw_linfo;
+
+	nr_linfo = prog_linfo->nr_linfo;
+	if (nr_skip >= nr_linfo)
+		return errno = ENOENT, NULL;
+
+	rec_size = prog_linfo->rec_size;
+	raw_linfo = prog_linfo->raw_linfo + (nr_skip * rec_size);
+	linfo = raw_linfo;
+	if (insn_off < linfo->insn_off)
+		return errno = ENOENT, NULL;
+
+	nr_linfo -= nr_skip;
+	for (i = 0; i < nr_linfo; i++) {
+		if (insn_off < linfo->insn_off)
+			break;
+
+		raw_linfo += rec_size;
+		linfo = raw_linfo;
+	}
+
+	return raw_linfo - rec_size;
+}
diff --git a/src/bpf_tracing.h b/src/bpf_tracing.h
new file mode 100644
index 0000000..2972dc2
--- /dev/null
+++ b/src/bpf_tracing.h
@@ -0,0 +1,670 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __BPF_TRACING_H__
+#define __BPF_TRACING_H__
+
+#include <bpf/bpf_helpers.h>
+
+/* Scan the ARCH passed in from ARCH env variable (see Makefile) */
+#if defined(__TARGET_ARCH_x86)
+	#define bpf_target_x86
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_s390)
+	#define bpf_target_s390
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_arm)
+	#define bpf_target_arm
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_arm64)
+	#define bpf_target_arm64
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_mips)
+	#define bpf_target_mips
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_powerpc)
+	#define bpf_target_powerpc
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_sparc)
+	#define bpf_target_sparc
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_riscv)
+	#define bpf_target_riscv
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_arc)
+	#define bpf_target_arc
+	#define bpf_target_defined
+#else
+
+/* Fall back to what the compiler says */
+#if defined(__x86_64__)
+	#define bpf_target_x86
+	#define bpf_target_defined
+#elif defined(__s390__)
+	#define bpf_target_s390
+	#define bpf_target_defined
+#elif defined(__arm__)
+	#define bpf_target_arm
+	#define bpf_target_defined
+#elif defined(__aarch64__)
+	#define bpf_target_arm64
+	#define bpf_target_defined
+#elif defined(__mips__)
+	#define bpf_target_mips
+	#define bpf_target_defined
+#elif defined(__powerpc__)
+	#define bpf_target_powerpc
+	#define bpf_target_defined
+#elif defined(__sparc__)
+	#define bpf_target_sparc
+	#define bpf_target_defined
+#elif defined(__riscv) && __riscv_xlen == 64
+	#define bpf_target_riscv
+	#define bpf_target_defined
+#elif defined(__arc__)
+	#define bpf_target_arc
+	#define bpf_target_defined
+#endif /* no compiler target */
+
+#endif
+
+#ifndef __BPF_TARGET_MISSING
+#define __BPF_TARGET_MISSING "GCC error \"Must specify a BPF target arch via __TARGET_ARCH_xxx\""
+#endif
+
+#if defined(bpf_target_x86)
+
+#if defined(__KERNEL__) || defined(__VMLINUX_H__)
+
+#define __PT_PARM1_REG di
+#define __PT_PARM2_REG si
+#define __PT_PARM3_REG dx
+#define __PT_PARM4_REG cx
+#define __PT_PARM5_REG r8
+#define __PT_RET_REG sp
+#define __PT_FP_REG bp
+#define __PT_RC_REG ax
+#define __PT_SP_REG sp
+#define __PT_IP_REG ip
+/* syscall uses r10 for PARM4 */
+#define PT_REGS_PARM4_SYSCALL(x) ((x)->r10)
+#define PT_REGS_PARM4_CORE_SYSCALL(x) BPF_CORE_READ(x, r10)
+
+#else
+
+#ifdef __i386__
+
+#define __PT_PARM1_REG eax
+#define __PT_PARM2_REG edx
+#define __PT_PARM3_REG ecx
+/* i386 kernel is built with -mregparm=3 */
+#define __PT_PARM4_REG __unsupported__
+#define __PT_PARM5_REG __unsupported__
+#define __PT_RET_REG esp
+#define __PT_FP_REG ebp
+#define __PT_RC_REG eax
+#define __PT_SP_REG esp
+#define __PT_IP_REG eip
+
+#else /* __i386__ */
+
+#define __PT_PARM1_REG rdi
+#define __PT_PARM2_REG rsi
+#define __PT_PARM3_REG rdx
+#define __PT_PARM4_REG rcx
+#define __PT_PARM5_REG r8
+#define __PT_RET_REG rsp
+#define __PT_FP_REG rbp
+#define __PT_RC_REG rax
+#define __PT_SP_REG rsp
+#define __PT_IP_REG rip
+/* syscall uses r10 for PARM4 */
+#define PT_REGS_PARM4_SYSCALL(x) ((x)->r10)
+#define PT_REGS_PARM4_CORE_SYSCALL(x) BPF_CORE_READ(x, r10)
+
+#endif /* __i386__ */
+
+#endif /* __KERNEL__ || __VMLINUX_H__ */
+
+#elif defined(bpf_target_s390)
+
+struct pt_regs___s390 {
+	unsigned long orig_gpr2;
+};
+
+/* s390 provides user_pt_regs instead of struct pt_regs to userspace */
+#define __PT_REGS_CAST(x) ((const user_pt_regs *)(x))
+#define __PT_PARM1_REG gprs[2]
+#define __PT_PARM2_REG gprs[3]
+#define __PT_PARM3_REG gprs[4]
+#define __PT_PARM4_REG gprs[5]
+#define __PT_PARM5_REG gprs[6]
+#define __PT_RET_REG grps[14]
+#define __PT_FP_REG gprs[11]	/* Works only with CONFIG_FRAME_POINTER */
+#define __PT_RC_REG gprs[2]
+#define __PT_SP_REG gprs[15]
+#define __PT_IP_REG psw.addr
+#define PT_REGS_PARM1_SYSCALL(x) PT_REGS_PARM1_CORE_SYSCALL(x)
+#define PT_REGS_PARM1_CORE_SYSCALL(x) BPF_CORE_READ((const struct pt_regs___s390 *)(x), orig_gpr2)
+
+#elif defined(bpf_target_arm)
+
+#define __PT_PARM1_REG uregs[0]
+#define __PT_PARM2_REG uregs[1]
+#define __PT_PARM3_REG uregs[2]
+#define __PT_PARM4_REG uregs[3]
+#define __PT_PARM5_REG uregs[4]
+#define __PT_RET_REG uregs[14]
+#define __PT_FP_REG uregs[11]	/* Works only with CONFIG_FRAME_POINTER */
+#define __PT_RC_REG uregs[0]
+#define __PT_SP_REG uregs[13]
+#define __PT_IP_REG uregs[12]
+
+#elif defined(bpf_target_arm64)
+
+struct pt_regs___arm64 {
+	unsigned long orig_x0;
+};
+
+/* arm64 provides struct user_pt_regs instead of struct pt_regs to userspace */
+#define __PT_REGS_CAST(x) ((const struct user_pt_regs *)(x))
+#define __PT_PARM1_REG regs[0]
+#define __PT_PARM2_REG regs[1]
+#define __PT_PARM3_REG regs[2]
+#define __PT_PARM4_REG regs[3]
+#define __PT_PARM5_REG regs[4]
+#define __PT_RET_REG regs[30]
+#define __PT_FP_REG regs[29]	/* Works only with CONFIG_FRAME_POINTER */
+#define __PT_RC_REG regs[0]
+#define __PT_SP_REG sp
+#define __PT_IP_REG pc
+#define PT_REGS_PARM1_SYSCALL(x) PT_REGS_PARM1_CORE_SYSCALL(x)
+#define PT_REGS_PARM1_CORE_SYSCALL(x) BPF_CORE_READ((const struct pt_regs___arm64 *)(x), orig_x0)
+
+#elif defined(bpf_target_mips)
+
+#define __PT_PARM1_REG regs[4]
+#define __PT_PARM2_REG regs[5]
+#define __PT_PARM3_REG regs[6]
+#define __PT_PARM4_REG regs[7]
+#define __PT_PARM5_REG regs[8]
+#define __PT_RET_REG regs[31]
+#define __PT_FP_REG regs[30]	/* Works only with CONFIG_FRAME_POINTER */
+#define __PT_RC_REG regs[2]
+#define __PT_SP_REG regs[29]
+#define __PT_IP_REG cp0_epc
+
+#elif defined(bpf_target_powerpc)
+
+#define __PT_PARM1_REG gpr[3]
+#define __PT_PARM2_REG gpr[4]
+#define __PT_PARM3_REG gpr[5]
+#define __PT_PARM4_REG gpr[6]
+#define __PT_PARM5_REG gpr[7]
+#define __PT_RET_REG regs[31]
+#define __PT_FP_REG __unsupported__
+#define __PT_RC_REG gpr[3]
+#define __PT_SP_REG sp
+#define __PT_IP_REG nip
+/* powerpc does not select ARCH_HAS_SYSCALL_WRAPPER. */
+#define PT_REGS_SYSCALL_REGS(ctx) ctx
+
+#elif defined(bpf_target_sparc)
+
+#define __PT_PARM1_REG u_regs[UREG_I0]
+#define __PT_PARM2_REG u_regs[UREG_I1]
+#define __PT_PARM3_REG u_regs[UREG_I2]
+#define __PT_PARM4_REG u_regs[UREG_I3]
+#define __PT_PARM5_REG u_regs[UREG_I4]
+#define __PT_RET_REG u_regs[UREG_I7]
+#define __PT_FP_REG __unsupported__
+#define __PT_RC_REG u_regs[UREG_I0]
+#define __PT_SP_REG u_regs[UREG_FP]
+/* Should this also be a bpf_target check for the sparc case? */
+#if defined(__arch64__)
+#define __PT_IP_REG tpc
+#else
+#define __PT_IP_REG pc
+#endif
+
+#elif defined(bpf_target_riscv)
+
+#define __PT_REGS_CAST(x) ((const struct user_regs_struct *)(x))
+#define __PT_PARM1_REG a0
+#define __PT_PARM2_REG a1
+#define __PT_PARM3_REG a2
+#define __PT_PARM4_REG a3
+#define __PT_PARM5_REG a4
+#define __PT_RET_REG ra
+#define __PT_FP_REG s0
+#define __PT_RC_REG a0
+#define __PT_SP_REG sp
+#define __PT_IP_REG pc
+/* riscv does not select ARCH_HAS_SYSCALL_WRAPPER. */
+#define PT_REGS_SYSCALL_REGS(ctx) ctx
+
+#elif defined(bpf_target_arc)
+
+/* arc provides struct user_pt_regs instead of struct pt_regs to userspace */
+#define __PT_REGS_CAST(x) ((const struct user_regs_struct *)(x))
+#define __PT_PARM1_REG scratch.r0
+#define __PT_PARM2_REG scratch.r1
+#define __PT_PARM3_REG scratch.r2
+#define __PT_PARM4_REG scratch.r3
+#define __PT_PARM5_REG scratch.r4
+#define __PT_RET_REG scratch.blink
+#define __PT_FP_REG __unsupported__
+#define __PT_RC_REG scratch.r0
+#define __PT_SP_REG scratch.sp
+#define __PT_IP_REG scratch.ret
+/* arc does not select ARCH_HAS_SYSCALL_WRAPPER. */
+#define PT_REGS_SYSCALL_REGS(ctx) ctx
+
+#endif
+
+#if defined(bpf_target_defined)
+
+struct pt_regs;
+
+/* allow some architecutres to override `struct pt_regs` */
+#ifndef __PT_REGS_CAST
+#define __PT_REGS_CAST(x) (x)
+#endif
+
+#define PT_REGS_PARM1(x) (__PT_REGS_CAST(x)->__PT_PARM1_REG)
+#define PT_REGS_PARM2(x) (__PT_REGS_CAST(x)->__PT_PARM2_REG)
+#define PT_REGS_PARM3(x) (__PT_REGS_CAST(x)->__PT_PARM3_REG)
+#define PT_REGS_PARM4(x) (__PT_REGS_CAST(x)->__PT_PARM4_REG)
+#define PT_REGS_PARM5(x) (__PT_REGS_CAST(x)->__PT_PARM5_REG)
+#define PT_REGS_RET(x) (__PT_REGS_CAST(x)->__PT_RET_REG)
+#define PT_REGS_FP(x) (__PT_REGS_CAST(x)->__PT_FP_REG)
+#define PT_REGS_RC(x) (__PT_REGS_CAST(x)->__PT_RC_REG)
+#define PT_REGS_SP(x) (__PT_REGS_CAST(x)->__PT_SP_REG)
+#define PT_REGS_IP(x) (__PT_REGS_CAST(x)->__PT_IP_REG)
+
+#define PT_REGS_PARM1_CORE(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM1_REG)
+#define PT_REGS_PARM2_CORE(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM2_REG)
+#define PT_REGS_PARM3_CORE(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM3_REG)
+#define PT_REGS_PARM4_CORE(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM4_REG)
+#define PT_REGS_PARM5_CORE(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_PARM5_REG)
+#define PT_REGS_RET_CORE(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_RET_REG)
+#define PT_REGS_FP_CORE(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_FP_REG)
+#define PT_REGS_RC_CORE(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_RC_REG)
+#define PT_REGS_SP_CORE(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_SP_REG)
+#define PT_REGS_IP_CORE(x) BPF_CORE_READ(__PT_REGS_CAST(x), __PT_IP_REG)
+
+#if defined(bpf_target_powerpc)
+
+#define BPF_KPROBE_READ_RET_IP(ip, ctx)		({ (ip) = (ctx)->link; })
+#define BPF_KRETPROBE_READ_RET_IP		BPF_KPROBE_READ_RET_IP
+
+#elif defined(bpf_target_sparc)
+
+#define BPF_KPROBE_READ_RET_IP(ip, ctx)		({ (ip) = PT_REGS_RET(ctx); })
+#define BPF_KRETPROBE_READ_RET_IP		BPF_KPROBE_READ_RET_IP
+
+#else
+
+#define BPF_KPROBE_READ_RET_IP(ip, ctx)					    \
+	({ bpf_probe_read_kernel(&(ip), sizeof(ip), (void *)PT_REGS_RET(ctx)); })
+#define BPF_KRETPROBE_READ_RET_IP(ip, ctx)				    \
+	({ bpf_probe_read_kernel(&(ip), sizeof(ip), (void *)(PT_REGS_FP(ctx) + sizeof(ip))); })
+
+#endif
+
+#ifndef PT_REGS_PARM1_SYSCALL
+#define PT_REGS_PARM1_SYSCALL(x) PT_REGS_PARM1(x)
+#endif
+#define PT_REGS_PARM2_SYSCALL(x) PT_REGS_PARM2(x)
+#define PT_REGS_PARM3_SYSCALL(x) PT_REGS_PARM3(x)
+#ifndef PT_REGS_PARM4_SYSCALL
+#define PT_REGS_PARM4_SYSCALL(x) PT_REGS_PARM4(x)
+#endif
+#define PT_REGS_PARM5_SYSCALL(x) PT_REGS_PARM5(x)
+
+#ifndef PT_REGS_PARM1_CORE_SYSCALL
+#define PT_REGS_PARM1_CORE_SYSCALL(x) PT_REGS_PARM1_CORE(x)
+#endif
+#define PT_REGS_PARM2_CORE_SYSCALL(x) PT_REGS_PARM2_CORE(x)
+#define PT_REGS_PARM3_CORE_SYSCALL(x) PT_REGS_PARM3_CORE(x)
+#ifndef PT_REGS_PARM4_CORE_SYSCALL
+#define PT_REGS_PARM4_CORE_SYSCALL(x) PT_REGS_PARM4_CORE(x)
+#endif
+#define PT_REGS_PARM5_CORE_SYSCALL(x) PT_REGS_PARM5_CORE(x)
+
+#else /* defined(bpf_target_defined) */
+
+#define PT_REGS_PARM1(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM2(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM3(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM4(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM5(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_RET(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_FP(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_RC(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_SP(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_IP(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+
+#define PT_REGS_PARM1_CORE(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM2_CORE(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM3_CORE(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM4_CORE(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM5_CORE(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_RET_CORE(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_FP_CORE(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_RC_CORE(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_SP_CORE(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_IP_CORE(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+
+#define BPF_KPROBE_READ_RET_IP(ip, ctx) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define BPF_KRETPROBE_READ_RET_IP(ip, ctx) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+
+#define PT_REGS_PARM1_SYSCALL(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM2_SYSCALL(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM3_SYSCALL(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM4_SYSCALL(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM5_SYSCALL(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+
+#define PT_REGS_PARM1_CORE_SYSCALL(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM2_CORE_SYSCALL(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM3_CORE_SYSCALL(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM4_CORE_SYSCALL(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+#define PT_REGS_PARM5_CORE_SYSCALL(x) ({ _Pragma(__BPF_TARGET_MISSING); 0l; })
+
+#endif /* defined(bpf_target_defined) */
+
+/*
+ * When invoked from a syscall handler kprobe, returns a pointer to a
+ * struct pt_regs containing syscall arguments and suitable for passing to
+ * PT_REGS_PARMn_SYSCALL() and PT_REGS_PARMn_CORE_SYSCALL().
+ */
+#ifndef PT_REGS_SYSCALL_REGS
+/* By default, assume that the arch selects ARCH_HAS_SYSCALL_WRAPPER. */
+#define PT_REGS_SYSCALL_REGS(ctx) ((struct pt_regs *)PT_REGS_PARM1(ctx))
+#endif
+
+#ifndef ___bpf_concat
+#define ___bpf_concat(a, b) a ## b
+#endif
+#ifndef ___bpf_apply
+#define ___bpf_apply(fn, n) ___bpf_concat(fn, n)
+#endif
+#ifndef ___bpf_nth
+#define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N
+#endif
+#ifndef ___bpf_narg
+#define ___bpf_narg(...) ___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
+#endif
+
+#define ___bpf_ctx_cast0()            ctx
+#define ___bpf_ctx_cast1(x)           ___bpf_ctx_cast0(), (void *)ctx[0]
+#define ___bpf_ctx_cast2(x, args...)  ___bpf_ctx_cast1(args), (void *)ctx[1]
+#define ___bpf_ctx_cast3(x, args...)  ___bpf_ctx_cast2(args), (void *)ctx[2]
+#define ___bpf_ctx_cast4(x, args...)  ___bpf_ctx_cast3(args), (void *)ctx[3]
+#define ___bpf_ctx_cast5(x, args...)  ___bpf_ctx_cast4(args), (void *)ctx[4]
+#define ___bpf_ctx_cast6(x, args...)  ___bpf_ctx_cast5(args), (void *)ctx[5]
+#define ___bpf_ctx_cast7(x, args...)  ___bpf_ctx_cast6(args), (void *)ctx[6]
+#define ___bpf_ctx_cast8(x, args...)  ___bpf_ctx_cast7(args), (void *)ctx[7]
+#define ___bpf_ctx_cast9(x, args...)  ___bpf_ctx_cast8(args), (void *)ctx[8]
+#define ___bpf_ctx_cast10(x, args...) ___bpf_ctx_cast9(args), (void *)ctx[9]
+#define ___bpf_ctx_cast11(x, args...) ___bpf_ctx_cast10(args), (void *)ctx[10]
+#define ___bpf_ctx_cast12(x, args...) ___bpf_ctx_cast11(args), (void *)ctx[11]
+#define ___bpf_ctx_cast(args...)      ___bpf_apply(___bpf_ctx_cast, ___bpf_narg(args))(args)
+
+/*
+ * BPF_PROG is a convenience wrapper for generic tp_btf/fentry/fexit and
+ * similar kinds of BPF programs, that accept input arguments as a single
+ * pointer to untyped u64 array, where each u64 can actually be a typed
+ * pointer or integer of different size. Instead of requring user to write
+ * manual casts and work with array elements by index, BPF_PROG macro
+ * allows user to declare a list of named and typed input arguments in the
+ * same syntax as for normal C function. All the casting is hidden and
+ * performed transparently, while user code can just assume working with
+ * function arguments of specified type and name.
+ *
+ * Original raw context argument is preserved as well as 'ctx' argument.
+ * This is useful when using BPF helpers that expect original context
+ * as one of the parameters (e.g., for bpf_perf_event_output()).
+ */
+#define BPF_PROG(name, args...)						    \
+name(unsigned long long *ctx);						    \
+static __always_inline typeof(name(0))					    \
+____##name(unsigned long long *ctx, ##args);				    \
+typeof(name(0)) name(unsigned long long *ctx)				    \
+{									    \
+	_Pragma("GCC diagnostic push")					    \
+	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")		    \
+	return ____##name(___bpf_ctx_cast(args));			    \
+	_Pragma("GCC diagnostic pop")					    \
+}									    \
+static __always_inline typeof(name(0))					    \
+____##name(unsigned long long *ctx, ##args)
+
+#ifndef ___bpf_nth2
+#define ___bpf_nth2(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13,	\
+		    _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, N, ...) N
+#endif
+#ifndef ___bpf_narg2
+#define ___bpf_narg2(...)	\
+	___bpf_nth2(_, ##__VA_ARGS__, 12, 12, 11, 11, 10, 10, 9, 9, 8, 8, 7, 7,	\
+		    6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0)
+#endif
+
+#define ___bpf_treg_cnt(t) \
+	__builtin_choose_expr(sizeof(t) == 1, 1,	\
+	__builtin_choose_expr(sizeof(t) == 2, 1,	\
+	__builtin_choose_expr(sizeof(t) == 4, 1,	\
+	__builtin_choose_expr(sizeof(t) == 8, 1,	\
+	__builtin_choose_expr(sizeof(t) == 16, 2,	\
+			      (void)0)))))
+
+#define ___bpf_reg_cnt0()		(0)
+#define ___bpf_reg_cnt1(t, x)		(___bpf_reg_cnt0() + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt2(t, x, args...)	(___bpf_reg_cnt1(args) + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt3(t, x, args...)	(___bpf_reg_cnt2(args) + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt4(t, x, args...)	(___bpf_reg_cnt3(args) + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt5(t, x, args...)	(___bpf_reg_cnt4(args) + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt6(t, x, args...)	(___bpf_reg_cnt5(args) + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt7(t, x, args...)	(___bpf_reg_cnt6(args) + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt8(t, x, args...)	(___bpf_reg_cnt7(args) + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt9(t, x, args...)	(___bpf_reg_cnt8(args) + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt10(t, x, args...)	(___bpf_reg_cnt9(args) + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt11(t, x, args...)	(___bpf_reg_cnt10(args) + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt12(t, x, args...)	(___bpf_reg_cnt11(args) + ___bpf_treg_cnt(t))
+#define ___bpf_reg_cnt(args...)	 ___bpf_apply(___bpf_reg_cnt, ___bpf_narg2(args))(args)
+
+#define ___bpf_union_arg(t, x, n) \
+	__builtin_choose_expr(sizeof(t) == 1, ({ union { __u8 z[1]; t x; } ___t = { .z = {ctx[n]}}; ___t.x; }), \
+	__builtin_choose_expr(sizeof(t) == 2, ({ union { __u16 z[1]; t x; } ___t = { .z = {ctx[n]} }; ___t.x; }), \
+	__builtin_choose_expr(sizeof(t) == 4, ({ union { __u32 z[1]; t x; } ___t = { .z = {ctx[n]} }; ___t.x; }), \
+	__builtin_choose_expr(sizeof(t) == 8, ({ union { __u64 z[1]; t x; } ___t = {.z = {ctx[n]} }; ___t.x; }), \
+	__builtin_choose_expr(sizeof(t) == 16, ({ union { __u64 z[2]; t x; } ___t = {.z = {ctx[n], ctx[n + 1]} }; ___t.x; }), \
+			      (void)0)))))
+
+#define ___bpf_ctx_arg0(n, args...)
+#define ___bpf_ctx_arg1(n, t, x)		, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt1(t, x))
+#define ___bpf_ctx_arg2(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt2(t, x, args)) ___bpf_ctx_arg1(n, args)
+#define ___bpf_ctx_arg3(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt3(t, x, args)) ___bpf_ctx_arg2(n, args)
+#define ___bpf_ctx_arg4(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt4(t, x, args)) ___bpf_ctx_arg3(n, args)
+#define ___bpf_ctx_arg5(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt5(t, x, args)) ___bpf_ctx_arg4(n, args)
+#define ___bpf_ctx_arg6(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt6(t, x, args)) ___bpf_ctx_arg5(n, args)
+#define ___bpf_ctx_arg7(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt7(t, x, args)) ___bpf_ctx_arg6(n, args)
+#define ___bpf_ctx_arg8(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt8(t, x, args)) ___bpf_ctx_arg7(n, args)
+#define ___bpf_ctx_arg9(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt9(t, x, args)) ___bpf_ctx_arg8(n, args)
+#define ___bpf_ctx_arg10(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt10(t, x, args)) ___bpf_ctx_arg9(n, args)
+#define ___bpf_ctx_arg11(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt11(t, x, args)) ___bpf_ctx_arg10(n, args)
+#define ___bpf_ctx_arg12(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt12(t, x, args)) ___bpf_ctx_arg11(n, args)
+#define ___bpf_ctx_arg(args...)	___bpf_apply(___bpf_ctx_arg, ___bpf_narg2(args))(___bpf_reg_cnt(args), args)
+
+#define ___bpf_ctx_decl0()
+#define ___bpf_ctx_decl1(t, x)			, t x
+#define ___bpf_ctx_decl2(t, x, args...)		, t x ___bpf_ctx_decl1(args)
+#define ___bpf_ctx_decl3(t, x, args...)		, t x ___bpf_ctx_decl2(args)
+#define ___bpf_ctx_decl4(t, x, args...)		, t x ___bpf_ctx_decl3(args)
+#define ___bpf_ctx_decl5(t, x, args...)		, t x ___bpf_ctx_decl4(args)
+#define ___bpf_ctx_decl6(t, x, args...)		, t x ___bpf_ctx_decl5(args)
+#define ___bpf_ctx_decl7(t, x, args...)		, t x ___bpf_ctx_decl6(args)
+#define ___bpf_ctx_decl8(t, x, args...)		, t x ___bpf_ctx_decl7(args)
+#define ___bpf_ctx_decl9(t, x, args...)		, t x ___bpf_ctx_decl8(args)
+#define ___bpf_ctx_decl10(t, x, args...)	, t x ___bpf_ctx_decl9(args)
+#define ___bpf_ctx_decl11(t, x, args...)	, t x ___bpf_ctx_decl10(args)
+#define ___bpf_ctx_decl12(t, x, args...)	, t x ___bpf_ctx_decl11(args)
+#define ___bpf_ctx_decl(args...)	___bpf_apply(___bpf_ctx_decl, ___bpf_narg2(args))(args)
+
+/*
+ * BPF_PROG2 is an enhanced version of BPF_PROG in order to handle struct
+ * arguments. Since each struct argument might take one or two u64 values
+ * in the trampoline stack, argument type size is needed to place proper number
+ * of u64 values for each argument. Therefore, BPF_PROG2 has different
+ * syntax from BPF_PROG. For example, for the following BPF_PROG syntax:
+ *
+ *   int BPF_PROG(test2, int a, int b) { ... }
+ *
+ * the corresponding BPF_PROG2 syntax is:
+ *
+ *   int BPF_PROG2(test2, int, a, int, b) { ... }
+ *
+ * where type and the corresponding argument name are separated by comma.
+ *
+ * Use BPF_PROG2 macro if one of the arguments might be a struct/union larger
+ * than 8 bytes:
+ *
+ *   int BPF_PROG2(test_struct_arg, struct bpf_testmod_struct_arg_1, a, int, b,
+ *		   int, c, int, d, struct bpf_testmod_struct_arg_2, e, int, ret)
+ *   {
+ *        // access a, b, c, d, e, and ret directly
+ *        ...
+ *   }
+ */
+#define BPF_PROG2(name, args...)						\
+name(unsigned long long *ctx);							\
+static __always_inline typeof(name(0))						\
+____##name(unsigned long long *ctx ___bpf_ctx_decl(args));			\
+typeof(name(0)) name(unsigned long long *ctx)					\
+{										\
+	return ____##name(ctx ___bpf_ctx_arg(args));				\
+}										\
+static __always_inline typeof(name(0))						\
+____##name(unsigned long long *ctx ___bpf_ctx_decl(args))
+
+struct pt_regs;
+
+#define ___bpf_kprobe_args0()           ctx
+#define ___bpf_kprobe_args1(x)          ___bpf_kprobe_args0(), (void *)PT_REGS_PARM1(ctx)
+#define ___bpf_kprobe_args2(x, args...) ___bpf_kprobe_args1(args), (void *)PT_REGS_PARM2(ctx)
+#define ___bpf_kprobe_args3(x, args...) ___bpf_kprobe_args2(args), (void *)PT_REGS_PARM3(ctx)
+#define ___bpf_kprobe_args4(x, args...) ___bpf_kprobe_args3(args), (void *)PT_REGS_PARM4(ctx)
+#define ___bpf_kprobe_args5(x, args...) ___bpf_kprobe_args4(args), (void *)PT_REGS_PARM5(ctx)
+#define ___bpf_kprobe_args(args...)     ___bpf_apply(___bpf_kprobe_args, ___bpf_narg(args))(args)
+
+/*
+ * BPF_KPROBE serves the same purpose for kprobes as BPF_PROG for
+ * tp_btf/fentry/fexit BPF programs. It hides the underlying platform-specific
+ * low-level way of getting kprobe input arguments from struct pt_regs, and
+ * provides a familiar typed and named function arguments syntax and
+ * semantics of accessing kprobe input paremeters.
+ *
+ * Original struct pt_regs* context is preserved as 'ctx' argument. This might
+ * be necessary when using BPF helpers like bpf_perf_event_output().
+ */
+#define BPF_KPROBE(name, args...)					    \
+name(struct pt_regs *ctx);						    \
+static __always_inline typeof(name(0))					    \
+____##name(struct pt_regs *ctx, ##args);				    \
+typeof(name(0)) name(struct pt_regs *ctx)				    \
+{									    \
+	_Pragma("GCC diagnostic push")					    \
+	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")		    \
+	return ____##name(___bpf_kprobe_args(args));			    \
+	_Pragma("GCC diagnostic pop")					    \
+}									    \
+static __always_inline typeof(name(0))					    \
+____##name(struct pt_regs *ctx, ##args)
+
+#define ___bpf_kretprobe_args0()       ctx
+#define ___bpf_kretprobe_args1(x)      ___bpf_kretprobe_args0(), (void *)PT_REGS_RC(ctx)
+#define ___bpf_kretprobe_args(args...) ___bpf_apply(___bpf_kretprobe_args, ___bpf_narg(args))(args)
+
+/*
+ * BPF_KRETPROBE is similar to BPF_KPROBE, except, it only provides optional
+ * return value (in addition to `struct pt_regs *ctx`), but no input
+ * arguments, because they will be clobbered by the time probed function
+ * returns.
+ */
+#define BPF_KRETPROBE(name, args...)					    \
+name(struct pt_regs *ctx);						    \
+static __always_inline typeof(name(0))					    \
+____##name(struct pt_regs *ctx, ##args);				    \
+typeof(name(0)) name(struct pt_regs *ctx)				    \
+{									    \
+	_Pragma("GCC diagnostic push")					    \
+	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")		    \
+	return ____##name(___bpf_kretprobe_args(args));			    \
+	_Pragma("GCC diagnostic pop")					    \
+}									    \
+static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args)
+
+/* If kernel has CONFIG_ARCH_HAS_SYSCALL_WRAPPER, read pt_regs directly */
+#define ___bpf_syscall_args0()           ctx
+#define ___bpf_syscall_args1(x)          ___bpf_syscall_args0(), (void *)PT_REGS_PARM1_SYSCALL(regs)
+#define ___bpf_syscall_args2(x, args...) ___bpf_syscall_args1(args), (void *)PT_REGS_PARM2_SYSCALL(regs)
+#define ___bpf_syscall_args3(x, args...) ___bpf_syscall_args2(args), (void *)PT_REGS_PARM3_SYSCALL(regs)
+#define ___bpf_syscall_args4(x, args...) ___bpf_syscall_args3(args), (void *)PT_REGS_PARM4_SYSCALL(regs)
+#define ___bpf_syscall_args5(x, args...) ___bpf_syscall_args4(args), (void *)PT_REGS_PARM5_SYSCALL(regs)
+#define ___bpf_syscall_args(args...)     ___bpf_apply(___bpf_syscall_args, ___bpf_narg(args))(args)
+
+/* If kernel doesn't have CONFIG_ARCH_HAS_SYSCALL_WRAPPER, we have to BPF_CORE_READ from pt_regs */
+#define ___bpf_syswrap_args0()           ctx
+#define ___bpf_syswrap_args1(x)          ___bpf_syswrap_args0(), (void *)PT_REGS_PARM1_CORE_SYSCALL(regs)
+#define ___bpf_syswrap_args2(x, args...) ___bpf_syswrap_args1(args), (void *)PT_REGS_PARM2_CORE_SYSCALL(regs)
+#define ___bpf_syswrap_args3(x, args...) ___bpf_syswrap_args2(args), (void *)PT_REGS_PARM3_CORE_SYSCALL(regs)
+#define ___bpf_syswrap_args4(x, args...) ___bpf_syswrap_args3(args), (void *)PT_REGS_PARM4_CORE_SYSCALL(regs)
+#define ___bpf_syswrap_args5(x, args...) ___bpf_syswrap_args4(args), (void *)PT_REGS_PARM5_CORE_SYSCALL(regs)
+#define ___bpf_syswrap_args(args...)     ___bpf_apply(___bpf_syswrap_args, ___bpf_narg(args))(args)
+
+/*
+ * BPF_KSYSCALL is a variant of BPF_KPROBE, which is intended for
+ * tracing syscall functions, like __x64_sys_close. It hides the underlying
+ * platform-specific low-level way of getting syscall input arguments from
+ * struct pt_regs, and provides a familiar typed and named function arguments
+ * syntax and semantics of accessing syscall input parameters.
+ *
+ * Original struct pt_regs * context is preserved as 'ctx' argument. This might
+ * be necessary when using BPF helpers like bpf_perf_event_output().
+ *
+ * At the moment BPF_KSYSCALL does not transparently handle all the calling
+ * convention quirks for the following syscalls:
+ *
+ * - mmap(): __ARCH_WANT_SYS_OLD_MMAP.
+ * - clone(): CONFIG_CLONE_BACKWARDS, CONFIG_CLONE_BACKWARDS2 and
+ *            CONFIG_CLONE_BACKWARDS3.
+ * - socket-related syscalls: __ARCH_WANT_SYS_SOCKETCALL.
+ * - compat syscalls.
+ *
+ * This may or may not change in the future. User needs to take extra measures
+ * to handle such quirks explicitly, if necessary.
+ *
+ * This macro relies on BPF CO-RE support and virtual __kconfig externs.
+ */
+#define BPF_KSYSCALL(name, args...)					    \
+name(struct pt_regs *ctx);						    \
+extern _Bool LINUX_HAS_SYSCALL_WRAPPER __kconfig;			    \
+static __always_inline typeof(name(0))					    \
+____##name(struct pt_regs *ctx, ##args);				    \
+typeof(name(0)) name(struct pt_regs *ctx)				    \
+{									    \
+	struct pt_regs *regs = LINUX_HAS_SYSCALL_WRAPPER		    \
+			       ? (struct pt_regs *)PT_REGS_PARM1(ctx)	    \
+			       : ctx;					    \
+	_Pragma("GCC diagnostic push")					    \
+	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")		    \
+	if (LINUX_HAS_SYSCALL_WRAPPER)					    \
+		return ____##name(___bpf_syswrap_args(args));		    \
+	else								    \
+		return ____##name(___bpf_syscall_args(args));		    \
+	_Pragma("GCC diagnostic pop")					    \
+}									    \
+static __always_inline typeof(name(0))					    \
+____##name(struct pt_regs *ctx, ##args)
+
+#define BPF_KPROBE_SYSCALL BPF_KSYSCALL
+
+#endif
diff --git a/src/btf.c b/src/btf.c
new file mode 100644
index 0000000..b032500
--- /dev/null
+++ b/src/btf.c
@@ -0,0 +1,5027 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2018 Facebook */
+
+#include <byteswap.h>
+#include <endian.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/utsname.h>
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/btf.h>
+#include <gelf.h>
+#include "btf.h"
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+#include "hashmap.h"
+#include "strset.h"
+
+#define BTF_MAX_NR_TYPES 0x7fffffffU
+#define BTF_MAX_STR_OFFSET 0x7fffffffU
+
+static struct btf_type btf_void;
+
+struct btf {
+	/* raw BTF data in native endianness */
+	void *raw_data;
+	/* raw BTF data in non-native endianness */
+	void *raw_data_swapped;
+	__u32 raw_size;
+	/* whether target endianness differs from the native one */
+	bool swapped_endian;
+
+	/*
+	 * When BTF is loaded from an ELF or raw memory it is stored
+	 * in a contiguous memory block. The hdr, type_data, and, strs_data
+	 * point inside that memory region to their respective parts of BTF
+	 * representation:
+	 *
+	 * +--------------------------------+
+	 * |  Header  |  Types  |  Strings  |
+	 * +--------------------------------+
+	 * ^          ^         ^
+	 * |          |         |
+	 * hdr        |         |
+	 * types_data-+         |
+	 * strs_data------------+
+	 *
+	 * If BTF data is later modified, e.g., due to types added or
+	 * removed, BTF deduplication performed, etc, this contiguous
+	 * representation is broken up into three independently allocated
+	 * memory regions to be able to modify them independently.
+	 * raw_data is nulled out at that point, but can be later allocated
+	 * and cached again if user calls btf__raw_data(), at which point
+	 * raw_data will contain a contiguous copy of header, types, and
+	 * strings:
+	 *
+	 * +----------+  +---------+  +-----------+
+	 * |  Header  |  |  Types  |  |  Strings  |
+	 * +----------+  +---------+  +-----------+
+	 * ^             ^            ^
+	 * |             |            |
+	 * hdr           |            |
+	 * types_data----+            |
+	 * strset__data(strs_set)-----+
+	 *
+	 *               +----------+---------+-----------+
+	 *               |  Header  |  Types  |  Strings  |
+	 * raw_data----->+----------+---------+-----------+
+	 */
+	struct btf_header *hdr;
+
+	void *types_data;
+	size_t types_data_cap; /* used size stored in hdr->type_len */
+
+	/* type ID to `struct btf_type *` lookup index
+	 * type_offs[0] corresponds to the first non-VOID type:
+	 *   - for base BTF it's type [1];
+	 *   - for split BTF it's the first non-base BTF type.
+	 */
+	__u32 *type_offs;
+	size_t type_offs_cap;
+	/* number of types in this BTF instance:
+	 *   - doesn't include special [0] void type;
+	 *   - for split BTF counts number of types added on top of base BTF.
+	 */
+	__u32 nr_types;
+	/* if not NULL, points to the base BTF on top of which the current
+	 * split BTF is based
+	 */
+	struct btf *base_btf;
+	/* BTF type ID of the first type in this BTF instance:
+	 *   - for base BTF it's equal to 1;
+	 *   - for split BTF it's equal to biggest type ID of base BTF plus 1.
+	 */
+	int start_id;
+	/* logical string offset of this BTF instance:
+	 *   - for base BTF it's equal to 0;
+	 *   - for split BTF it's equal to total size of base BTF's string section size.
+	 */
+	int start_str_off;
+
+	/* only one of strs_data or strs_set can be non-NULL, depending on
+	 * whether BTF is in a modifiable state (strs_set is used) or not
+	 * (strs_data points inside raw_data)
+	 */
+	void *strs_data;
+	/* a set of unique strings */
+	struct strset *strs_set;
+	/* whether strings are already deduplicated */
+	bool strs_deduped;
+
+	/* BTF object FD, if loaded into kernel */
+	int fd;
+
+	/* Pointer size (in bytes) for a target architecture of this BTF */
+	int ptr_sz;
+};
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64) (unsigned long) ptr;
+}
+
+/* Ensure given dynamically allocated memory region pointed to by *data* with
+ * capacity of *cap_cnt* elements each taking *elem_sz* bytes has enough
+ * memory to accommodate *add_cnt* new elements, assuming *cur_cnt* elements
+ * are already used. At most *max_cnt* elements can be ever allocated.
+ * If necessary, memory is reallocated and all existing data is copied over,
+ * new pointer to the memory region is stored at *data, new memory region
+ * capacity (in number of elements) is stored in *cap.
+ * On success, memory pointer to the beginning of unused memory is returned.
+ * On error, NULL is returned.
+ */
+void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
+		     size_t cur_cnt, size_t max_cnt, size_t add_cnt)
+{
+	size_t new_cnt;
+	void *new_data;
+
+	if (cur_cnt + add_cnt <= *cap_cnt)
+		return *data + cur_cnt * elem_sz;
+
+	/* requested more than the set limit */
+	if (cur_cnt + add_cnt > max_cnt)
+		return NULL;
+
+	new_cnt = *cap_cnt;
+	new_cnt += new_cnt / 4;		  /* expand by 25% */
+	if (new_cnt < 16)		  /* but at least 16 elements */
+		new_cnt = 16;
+	if (new_cnt > max_cnt)		  /* but not exceeding a set limit */
+		new_cnt = max_cnt;
+	if (new_cnt < cur_cnt + add_cnt)  /* also ensure we have enough memory */
+		new_cnt = cur_cnt + add_cnt;
+
+	new_data = libbpf_reallocarray(*data, new_cnt, elem_sz);
+	if (!new_data)
+		return NULL;
+
+	/* zero out newly allocated portion of memory */
+	memset(new_data + (*cap_cnt) * elem_sz, 0, (new_cnt - *cap_cnt) * elem_sz);
+
+	*data = new_data;
+	*cap_cnt = new_cnt;
+	return new_data + cur_cnt * elem_sz;
+}
+
+/* Ensure given dynamically allocated memory region has enough allocated space
+ * to accommodate *need_cnt* elements of size *elem_sz* bytes each
+ */
+int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt)
+{
+	void *p;
+
+	if (need_cnt <= *cap_cnt)
+		return 0;
+
+	p = libbpf_add_mem(data, cap_cnt, elem_sz, *cap_cnt, SIZE_MAX, need_cnt - *cap_cnt);
+	if (!p)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void *btf_add_type_offs_mem(struct btf *btf, size_t add_cnt)
+{
+	return libbpf_add_mem((void **)&btf->type_offs, &btf->type_offs_cap, sizeof(__u32),
+			      btf->nr_types, BTF_MAX_NR_TYPES, add_cnt);
+}
+
+static int btf_add_type_idx_entry(struct btf *btf, __u32 type_off)
+{
+	__u32 *p;
+
+	p = btf_add_type_offs_mem(btf, 1);
+	if (!p)
+		return -ENOMEM;
+
+	*p = type_off;
+	return 0;
+}
+
+static void btf_bswap_hdr(struct btf_header *h)
+{
+	h->magic = bswap_16(h->magic);
+	h->hdr_len = bswap_32(h->hdr_len);
+	h->type_off = bswap_32(h->type_off);
+	h->type_len = bswap_32(h->type_len);
+	h->str_off = bswap_32(h->str_off);
+	h->str_len = bswap_32(h->str_len);
+}
+
+static int btf_parse_hdr(struct btf *btf)
+{
+	struct btf_header *hdr = btf->hdr;
+	__u32 meta_left;
+
+	if (btf->raw_size < sizeof(struct btf_header)) {
+		pr_debug("BTF header not found\n");
+		return -EINVAL;
+	}
+
+	if (hdr->magic == bswap_16(BTF_MAGIC)) {
+		btf->swapped_endian = true;
+		if (bswap_32(hdr->hdr_len) != sizeof(struct btf_header)) {
+			pr_warn("Can't load BTF with non-native endianness due to unsupported header length %u\n",
+				bswap_32(hdr->hdr_len));
+			return -ENOTSUP;
+		}
+		btf_bswap_hdr(hdr);
+	} else if (hdr->magic != BTF_MAGIC) {
+		pr_debug("Invalid BTF magic: %x\n", hdr->magic);
+		return -EINVAL;
+	}
+
+	if (btf->raw_size < hdr->hdr_len) {
+		pr_debug("BTF header len %u larger than data size %u\n",
+			 hdr->hdr_len, btf->raw_size);
+		return -EINVAL;
+	}
+
+	meta_left = btf->raw_size - hdr->hdr_len;
+	if (meta_left < (long long)hdr->str_off + hdr->str_len) {
+		pr_debug("Invalid BTF total size: %u\n", btf->raw_size);
+		return -EINVAL;
+	}
+
+	if ((long long)hdr->type_off + hdr->type_len > hdr->str_off) {
+		pr_debug("Invalid BTF data sections layout: type data at %u + %u, strings data at %u + %u\n",
+			 hdr->type_off, hdr->type_len, hdr->str_off, hdr->str_len);
+		return -EINVAL;
+	}
+
+	if (hdr->type_off % 4) {
+		pr_debug("BTF type section is not aligned to 4 bytes\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int btf_parse_str_sec(struct btf *btf)
+{
+	const struct btf_header *hdr = btf->hdr;
+	const char *start = btf->strs_data;
+	const char *end = start + btf->hdr->str_len;
+
+	if (btf->base_btf && hdr->str_len == 0)
+		return 0;
+	if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_STR_OFFSET || end[-1]) {
+		pr_debug("Invalid BTF string section\n");
+		return -EINVAL;
+	}
+	if (!btf->base_btf && start[0]) {
+		pr_debug("Invalid BTF string section\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int btf_type_size(const struct btf_type *t)
+{
+	const int base_size = sizeof(struct btf_type);
+	__u16 vlen = btf_vlen(t);
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_FWD:
+	case BTF_KIND_CONST:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_FUNC:
+	case BTF_KIND_FLOAT:
+	case BTF_KIND_TYPE_TAG:
+		return base_size;
+	case BTF_KIND_INT:
+		return base_size + sizeof(__u32);
+	case BTF_KIND_ENUM:
+		return base_size + vlen * sizeof(struct btf_enum);
+	case BTF_KIND_ENUM64:
+		return base_size + vlen * sizeof(struct btf_enum64);
+	case BTF_KIND_ARRAY:
+		return base_size + sizeof(struct btf_array);
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+		return base_size + vlen * sizeof(struct btf_member);
+	case BTF_KIND_FUNC_PROTO:
+		return base_size + vlen * sizeof(struct btf_param);
+	case BTF_KIND_VAR:
+		return base_size + sizeof(struct btf_var);
+	case BTF_KIND_DATASEC:
+		return base_size + vlen * sizeof(struct btf_var_secinfo);
+	case BTF_KIND_DECL_TAG:
+		return base_size + sizeof(struct btf_decl_tag);
+	default:
+		pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
+		return -EINVAL;
+	}
+}
+
+static void btf_bswap_type_base(struct btf_type *t)
+{
+	t->name_off = bswap_32(t->name_off);
+	t->info = bswap_32(t->info);
+	t->type = bswap_32(t->type);
+}
+
+static int btf_bswap_type_rest(struct btf_type *t)
+{
+	struct btf_var_secinfo *v;
+	struct btf_enum64 *e64;
+	struct btf_member *m;
+	struct btf_array *a;
+	struct btf_param *p;
+	struct btf_enum *e;
+	__u16 vlen = btf_vlen(t);
+	int i;
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_FWD:
+	case BTF_KIND_CONST:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_FUNC:
+	case BTF_KIND_FLOAT:
+	case BTF_KIND_TYPE_TAG:
+		return 0;
+	case BTF_KIND_INT:
+		*(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
+		return 0;
+	case BTF_KIND_ENUM:
+		for (i = 0, e = btf_enum(t); i < vlen; i++, e++) {
+			e->name_off = bswap_32(e->name_off);
+			e->val = bswap_32(e->val);
+		}
+		return 0;
+	case BTF_KIND_ENUM64:
+		for (i = 0, e64 = btf_enum64(t); i < vlen; i++, e64++) {
+			e64->name_off = bswap_32(e64->name_off);
+			e64->val_lo32 = bswap_32(e64->val_lo32);
+			e64->val_hi32 = bswap_32(e64->val_hi32);
+		}
+		return 0;
+	case BTF_KIND_ARRAY:
+		a = btf_array(t);
+		a->type = bswap_32(a->type);
+		a->index_type = bswap_32(a->index_type);
+		a->nelems = bswap_32(a->nelems);
+		return 0;
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+		for (i = 0, m = btf_members(t); i < vlen; i++, m++) {
+			m->name_off = bswap_32(m->name_off);
+			m->type = bswap_32(m->type);
+			m->offset = bswap_32(m->offset);
+		}
+		return 0;
+	case BTF_KIND_FUNC_PROTO:
+		for (i = 0, p = btf_params(t); i < vlen; i++, p++) {
+			p->name_off = bswap_32(p->name_off);
+			p->type = bswap_32(p->type);
+		}
+		return 0;
+	case BTF_KIND_VAR:
+		btf_var(t)->linkage = bswap_32(btf_var(t)->linkage);
+		return 0;
+	case BTF_KIND_DATASEC:
+		for (i = 0, v = btf_var_secinfos(t); i < vlen; i++, v++) {
+			v->type = bswap_32(v->type);
+			v->offset = bswap_32(v->offset);
+			v->size = bswap_32(v->size);
+		}
+		return 0;
+	case BTF_KIND_DECL_TAG:
+		btf_decl_tag(t)->component_idx = bswap_32(btf_decl_tag(t)->component_idx);
+		return 0;
+	default:
+		pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
+		return -EINVAL;
+	}
+}
+
+static int btf_parse_type_sec(struct btf *btf)
+{
+	struct btf_header *hdr = btf->hdr;
+	void *next_type = btf->types_data;
+	void *end_type = next_type + hdr->type_len;
+	int err, type_size;
+
+	while (next_type + sizeof(struct btf_type) <= end_type) {
+		if (btf->swapped_endian)
+			btf_bswap_type_base(next_type);
+
+		type_size = btf_type_size(next_type);
+		if (type_size < 0)
+			return type_size;
+		if (next_type + type_size > end_type) {
+			pr_warn("BTF type [%d] is malformed\n", btf->start_id + btf->nr_types);
+			return -EINVAL;
+		}
+
+		if (btf->swapped_endian && btf_bswap_type_rest(next_type))
+			return -EINVAL;
+
+		err = btf_add_type_idx_entry(btf, next_type - btf->types_data);
+		if (err)
+			return err;
+
+		next_type += type_size;
+		btf->nr_types++;
+	}
+
+	if (next_type != end_type) {
+		pr_warn("BTF types data is malformed\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+__u32 btf__type_cnt(const struct btf *btf)
+{
+	return btf->start_id + btf->nr_types;
+}
+
+const struct btf *btf__base_btf(const struct btf *btf)
+{
+	return btf->base_btf;
+}
+
+/* internal helper returning non-const pointer to a type */
+struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id)
+{
+	if (type_id == 0)
+		return &btf_void;
+	if (type_id < btf->start_id)
+		return btf_type_by_id(btf->base_btf, type_id);
+	return btf->types_data + btf->type_offs[type_id - btf->start_id];
+}
+
+const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
+{
+	if (type_id >= btf->start_id + btf->nr_types)
+		return errno = EINVAL, NULL;
+	return btf_type_by_id((struct btf *)btf, type_id);
+}
+
+static int determine_ptr_size(const struct btf *btf)
+{
+	static const char * const long_aliases[] = {
+		"long",
+		"long int",
+		"int long",
+		"unsigned long",
+		"long unsigned",
+		"unsigned long int",
+		"unsigned int long",
+		"long unsigned int",
+		"long int unsigned",
+		"int unsigned long",
+		"int long unsigned",
+	};
+	const struct btf_type *t;
+	const char *name;
+	int i, j, n;
+
+	if (btf->base_btf && btf->base_btf->ptr_sz > 0)
+		return btf->base_btf->ptr_sz;
+
+	n = btf__type_cnt(btf);
+	for (i = 1; i < n; i++) {
+		t = btf__type_by_id(btf, i);
+		if (!btf_is_int(t))
+			continue;
+
+		if (t->size != 4 && t->size != 8)
+			continue;
+
+		name = btf__name_by_offset(btf, t->name_off);
+		if (!name)
+			continue;
+
+		for (j = 0; j < ARRAY_SIZE(long_aliases); j++) {
+			if (strcmp(name, long_aliases[j]) == 0)
+				return t->size;
+		}
+	}
+
+	return -1;
+}
+
+static size_t btf_ptr_sz(const struct btf *btf)
+{
+	if (!btf->ptr_sz)
+		((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
+	return btf->ptr_sz < 0 ? sizeof(void *) : btf->ptr_sz;
+}
+
+/* Return pointer size this BTF instance assumes. The size is heuristically
+ * determined by looking for 'long' or 'unsigned long' integer type and
+ * recording its size in bytes. If BTF type information doesn't have any such
+ * type, this function returns 0. In the latter case, native architecture's
+ * pointer size is assumed, so will be either 4 or 8, depending on
+ * architecture that libbpf was compiled for. It's possible to override
+ * guessed value by using btf__set_pointer_size() API.
+ */
+size_t btf__pointer_size(const struct btf *btf)
+{
+	if (!btf->ptr_sz)
+		((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
+
+	if (btf->ptr_sz < 0)
+		/* not enough BTF type info to guess */
+		return 0;
+
+	return btf->ptr_sz;
+}
+
+/* Override or set pointer size in bytes. Only values of 4 and 8 are
+ * supported.
+ */
+int btf__set_pointer_size(struct btf *btf, size_t ptr_sz)
+{
+	if (ptr_sz != 4 && ptr_sz != 8)
+		return libbpf_err(-EINVAL);
+	btf->ptr_sz = ptr_sz;
+	return 0;
+}
+
+static bool is_host_big_endian(void)
+{
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	return false;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+	return true;
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+}
+
+enum btf_endianness btf__endianness(const struct btf *btf)
+{
+	if (is_host_big_endian())
+		return btf->swapped_endian ? BTF_LITTLE_ENDIAN : BTF_BIG_ENDIAN;
+	else
+		return btf->swapped_endian ? BTF_BIG_ENDIAN : BTF_LITTLE_ENDIAN;
+}
+
+int btf__set_endianness(struct btf *btf, enum btf_endianness endian)
+{
+	if (endian != BTF_LITTLE_ENDIAN && endian != BTF_BIG_ENDIAN)
+		return libbpf_err(-EINVAL);
+
+	btf->swapped_endian = is_host_big_endian() != (endian == BTF_BIG_ENDIAN);
+	if (!btf->swapped_endian) {
+		free(btf->raw_data_swapped);
+		btf->raw_data_swapped = NULL;
+	}
+	return 0;
+}
+
+static bool btf_type_is_void(const struct btf_type *t)
+{
+	return t == &btf_void || btf_is_fwd(t);
+}
+
+static bool btf_type_is_void_or_null(const struct btf_type *t)
+{
+	return !t || btf_type_is_void(t);
+}
+
+#define MAX_RESOLVE_DEPTH 32
+
+__s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
+{
+	const struct btf_array *array;
+	const struct btf_type *t;
+	__u32 nelems = 1;
+	__s64 size = -1;
+	int i;
+
+	t = btf__type_by_id(btf, type_id);
+	for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t); i++) {
+		switch (btf_kind(t)) {
+		case BTF_KIND_INT:
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION:
+		case BTF_KIND_ENUM:
+		case BTF_KIND_ENUM64:
+		case BTF_KIND_DATASEC:
+		case BTF_KIND_FLOAT:
+			size = t->size;
+			goto done;
+		case BTF_KIND_PTR:
+			size = btf_ptr_sz(btf);
+			goto done;
+		case BTF_KIND_TYPEDEF:
+		case BTF_KIND_VOLATILE:
+		case BTF_KIND_CONST:
+		case BTF_KIND_RESTRICT:
+		case BTF_KIND_VAR:
+		case BTF_KIND_DECL_TAG:
+		case BTF_KIND_TYPE_TAG:
+			type_id = t->type;
+			break;
+		case BTF_KIND_ARRAY:
+			array = btf_array(t);
+			if (nelems && array->nelems > UINT32_MAX / nelems)
+				return libbpf_err(-E2BIG);
+			nelems *= array->nelems;
+			type_id = array->type;
+			break;
+		default:
+			return libbpf_err(-EINVAL);
+		}
+
+		t = btf__type_by_id(btf, type_id);
+	}
+
+done:
+	if (size < 0)
+		return libbpf_err(-EINVAL);
+	if (nelems && size > UINT32_MAX / nelems)
+		return libbpf_err(-E2BIG);
+
+	return nelems * size;
+}
+
+int btf__align_of(const struct btf *btf, __u32 id)
+{
+	const struct btf_type *t = btf__type_by_id(btf, id);
+	__u16 kind = btf_kind(t);
+
+	switch (kind) {
+	case BTF_KIND_INT:
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+	case BTF_KIND_FLOAT:
+		return min(btf_ptr_sz(btf), (size_t)t->size);
+	case BTF_KIND_PTR:
+		return btf_ptr_sz(btf);
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_CONST:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_TYPE_TAG:
+		return btf__align_of(btf, t->type);
+	case BTF_KIND_ARRAY:
+		return btf__align_of(btf, btf_array(t)->type);
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		const struct btf_member *m = btf_members(t);
+		__u16 vlen = btf_vlen(t);
+		int i, max_align = 1, align;
+
+		for (i = 0; i < vlen; i++, m++) {
+			align = btf__align_of(btf, m->type);
+			if (align <= 0)
+				return libbpf_err(align);
+			max_align = max(max_align, align);
+
+			/* if field offset isn't aligned according to field
+			 * type's alignment, then struct must be packed
+			 */
+			if (btf_member_bitfield_size(t, i) == 0 &&
+			    (m->offset % (8 * align)) != 0)
+				return 1;
+		}
+
+		/* if struct/union size isn't a multiple of its alignment,
+		 * then struct must be packed
+		 */
+		if ((t->size % max_align) != 0)
+			return 1;
+
+		return max_align;
+	}
+	default:
+		pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
+		return errno = EINVAL, 0;
+	}
+}
+
+int btf__resolve_type(const struct btf *btf, __u32 type_id)
+{
+	const struct btf_type *t;
+	int depth = 0;
+
+	t = btf__type_by_id(btf, type_id);
+	while (depth < MAX_RESOLVE_DEPTH &&
+	       !btf_type_is_void_or_null(t) &&
+	       (btf_is_mod(t) || btf_is_typedef(t) || btf_is_var(t))) {
+		type_id = t->type;
+		t = btf__type_by_id(btf, type_id);
+		depth++;
+	}
+
+	if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
+		return libbpf_err(-EINVAL);
+
+	return type_id;
+}
+
+__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
+{
+	__u32 i, nr_types = btf__type_cnt(btf);
+
+	if (!strcmp(type_name, "void"))
+		return 0;
+
+	for (i = 1; i < nr_types; i++) {
+		const struct btf_type *t = btf__type_by_id(btf, i);
+		const char *name = btf__name_by_offset(btf, t->name_off);
+
+		if (name && !strcmp(type_name, name))
+			return i;
+	}
+
+	return libbpf_err(-ENOENT);
+}
+
+static __s32 btf_find_by_name_kind(const struct btf *btf, int start_id,
+				   const char *type_name, __u32 kind)
+{
+	__u32 i, nr_types = btf__type_cnt(btf);
+
+	if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void"))
+		return 0;
+
+	for (i = start_id; i < nr_types; i++) {
+		const struct btf_type *t = btf__type_by_id(btf, i);
+		const char *name;
+
+		if (btf_kind(t) != kind)
+			continue;
+		name = btf__name_by_offset(btf, t->name_off);
+		if (name && !strcmp(type_name, name))
+			return i;
+	}
+
+	return libbpf_err(-ENOENT);
+}
+
+__s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name,
+				 __u32 kind)
+{
+	return btf_find_by_name_kind(btf, btf->start_id, type_name, kind);
+}
+
+__s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
+			     __u32 kind)
+{
+	return btf_find_by_name_kind(btf, 1, type_name, kind);
+}
+
+static bool btf_is_modifiable(const struct btf *btf)
+{
+	return (void *)btf->hdr != btf->raw_data;
+}
+
+void btf__free(struct btf *btf)
+{
+	if (IS_ERR_OR_NULL(btf))
+		return;
+
+	if (btf->fd >= 0)
+		close(btf->fd);
+
+	if (btf_is_modifiable(btf)) {
+		/* if BTF was modified after loading, it will have a split
+		 * in-memory representation for header, types, and strings
+		 * sections, so we need to free all of them individually. It
+		 * might still have a cached contiguous raw data present,
+		 * which will be unconditionally freed below.
+		 */
+		free(btf->hdr);
+		free(btf->types_data);
+		strset__free(btf->strs_set);
+	}
+	free(btf->raw_data);
+	free(btf->raw_data_swapped);
+	free(btf->type_offs);
+	free(btf);
+}
+
+static struct btf *btf_new_empty(struct btf *base_btf)
+{
+	struct btf *btf;
+
+	btf = calloc(1, sizeof(*btf));
+	if (!btf)
+		return ERR_PTR(-ENOMEM);
+
+	btf->nr_types = 0;
+	btf->start_id = 1;
+	btf->start_str_off = 0;
+	btf->fd = -1;
+	btf->ptr_sz = sizeof(void *);
+	btf->swapped_endian = false;
+
+	if (base_btf) {
+		btf->base_btf = base_btf;
+		btf->start_id = btf__type_cnt(base_btf);
+		btf->start_str_off = base_btf->hdr->str_len;
+	}
+
+	/* +1 for empty string at offset 0 */
+	btf->raw_size = sizeof(struct btf_header) + (base_btf ? 0 : 1);
+	btf->raw_data = calloc(1, btf->raw_size);
+	if (!btf->raw_data) {
+		free(btf);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	btf->hdr = btf->raw_data;
+	btf->hdr->hdr_len = sizeof(struct btf_header);
+	btf->hdr->magic = BTF_MAGIC;
+	btf->hdr->version = BTF_VERSION;
+
+	btf->types_data = btf->raw_data + btf->hdr->hdr_len;
+	btf->strs_data = btf->raw_data + btf->hdr->hdr_len;
+	btf->hdr->str_len = base_btf ? 0 : 1; /* empty string at offset 0 */
+
+	return btf;
+}
+
+struct btf *btf__new_empty(void)
+{
+	return libbpf_ptr(btf_new_empty(NULL));
+}
+
+struct btf *btf__new_empty_split(struct btf *base_btf)
+{
+	return libbpf_ptr(btf_new_empty(base_btf));
+}
+
+static struct btf *btf_new(const void *data, __u32 size, struct btf *base_btf)
+{
+	struct btf *btf;
+	int err;
+
+	btf = calloc(1, sizeof(struct btf));
+	if (!btf)
+		return ERR_PTR(-ENOMEM);
+
+	btf->nr_types = 0;
+	btf->start_id = 1;
+	btf->start_str_off = 0;
+	btf->fd = -1;
+
+	if (base_btf) {
+		btf->base_btf = base_btf;
+		btf->start_id = btf__type_cnt(base_btf);
+		btf->start_str_off = base_btf->hdr->str_len;
+	}
+
+	btf->raw_data = malloc(size);
+	if (!btf->raw_data) {
+		err = -ENOMEM;
+		goto done;
+	}
+	memcpy(btf->raw_data, data, size);
+	btf->raw_size = size;
+
+	btf->hdr = btf->raw_data;
+	err = btf_parse_hdr(btf);
+	if (err)
+		goto done;
+
+	btf->strs_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->str_off;
+	btf->types_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->type_off;
+
+	err = btf_parse_str_sec(btf);
+	err = err ?: btf_parse_type_sec(btf);
+	if (err)
+		goto done;
+
+done:
+	if (err) {
+		btf__free(btf);
+		return ERR_PTR(err);
+	}
+
+	return btf;
+}
+
+struct btf *btf__new(const void *data, __u32 size)
+{
+	return libbpf_ptr(btf_new(data, size, NULL));
+}
+
+static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
+				 struct btf_ext **btf_ext)
+{
+	Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
+	int err = 0, fd = -1, idx = 0;
+	struct btf *btf = NULL;
+	Elf_Scn *scn = NULL;
+	Elf *elf = NULL;
+	GElf_Ehdr ehdr;
+	size_t shstrndx;
+
+	if (elf_version(EV_CURRENT) == EV_NONE) {
+		pr_warn("failed to init libelf for %s\n", path);
+		return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
+	}
+
+	fd = open(path, O_RDONLY | O_CLOEXEC);
+	if (fd < 0) {
+		err = -errno;
+		pr_warn("failed to open %s: %s\n", path, strerror(errno));
+		return ERR_PTR(err);
+	}
+
+	err = -LIBBPF_ERRNO__FORMAT;
+
+	elf = elf_begin(fd, ELF_C_READ, NULL);
+	if (!elf) {
+		pr_warn("failed to open %s as ELF file\n", path);
+		goto done;
+	}
+	if (!gelf_getehdr(elf, &ehdr)) {
+		pr_warn("failed to get EHDR from %s\n", path);
+		goto done;
+	}
+
+	if (elf_getshdrstrndx(elf, &shstrndx)) {
+		pr_warn("failed to get section names section index for %s\n",
+			path);
+		goto done;
+	}
+
+	if (!elf_rawdata(elf_getscn(elf, shstrndx), NULL)) {
+		pr_warn("failed to get e_shstrndx from %s\n", path);
+		goto done;
+	}
+
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		GElf_Shdr sh;
+		char *name;
+
+		idx++;
+		if (gelf_getshdr(scn, &sh) != &sh) {
+			pr_warn("failed to get section(%d) header from %s\n",
+				idx, path);
+			goto done;
+		}
+		name = elf_strptr(elf, shstrndx, sh.sh_name);
+		if (!name) {
+			pr_warn("failed to get section(%d) name from %s\n",
+				idx, path);
+			goto done;
+		}
+		if (strcmp(name, BTF_ELF_SEC) == 0) {
+			btf_data = elf_getdata(scn, 0);
+			if (!btf_data) {
+				pr_warn("failed to get section(%d, %s) data from %s\n",
+					idx, name, path);
+				goto done;
+			}
+			continue;
+		} else if (btf_ext && strcmp(name, BTF_EXT_ELF_SEC) == 0) {
+			btf_ext_data = elf_getdata(scn, 0);
+			if (!btf_ext_data) {
+				pr_warn("failed to get section(%d, %s) data from %s\n",
+					idx, name, path);
+				goto done;
+			}
+			continue;
+		}
+	}
+
+	err = 0;
+
+	if (!btf_data) {
+		pr_warn("failed to find '%s' ELF section in %s\n", BTF_ELF_SEC, path);
+		err = -ENOENT;
+		goto done;
+	}
+	btf = btf_new(btf_data->d_buf, btf_data->d_size, base_btf);
+	err = libbpf_get_error(btf);
+	if (err)
+		goto done;
+
+	switch (gelf_getclass(elf)) {
+	case ELFCLASS32:
+		btf__set_pointer_size(btf, 4);
+		break;
+	case ELFCLASS64:
+		btf__set_pointer_size(btf, 8);
+		break;
+	default:
+		pr_warn("failed to get ELF class (bitness) for %s\n", path);
+		break;
+	}
+
+	if (btf_ext && btf_ext_data) {
+		*btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
+		err = libbpf_get_error(*btf_ext);
+		if (err)
+			goto done;
+	} else if (btf_ext) {
+		*btf_ext = NULL;
+	}
+done:
+	if (elf)
+		elf_end(elf);
+	close(fd);
+
+	if (!err)
+		return btf;
+
+	if (btf_ext)
+		btf_ext__free(*btf_ext);
+	btf__free(btf);
+
+	return ERR_PTR(err);
+}
+
+struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
+{
+	return libbpf_ptr(btf_parse_elf(path, NULL, btf_ext));
+}
+
+struct btf *btf__parse_elf_split(const char *path, struct btf *base_btf)
+{
+	return libbpf_ptr(btf_parse_elf(path, base_btf, NULL));
+}
+
+static struct btf *btf_parse_raw(const char *path, struct btf *base_btf)
+{
+	struct btf *btf = NULL;
+	void *data = NULL;
+	FILE *f = NULL;
+	__u16 magic;
+	int err = 0;
+	long sz;
+
+	f = fopen(path, "rb");
+	if (!f) {
+		err = -errno;
+		goto err_out;
+	}
+
+	/* check BTF magic */
+	if (fread(&magic, 1, sizeof(magic), f) < sizeof(magic)) {
+		err = -EIO;
+		goto err_out;
+	}
+	if (magic != BTF_MAGIC && magic != bswap_16(BTF_MAGIC)) {
+		/* definitely not a raw BTF */
+		err = -EPROTO;
+		goto err_out;
+	}
+
+	/* get file size */
+	if (fseek(f, 0, SEEK_END)) {
+		err = -errno;
+		goto err_out;
+	}
+	sz = ftell(f);
+	if (sz < 0) {
+		err = -errno;
+		goto err_out;
+	}
+	/* rewind to the start */
+	if (fseek(f, 0, SEEK_SET)) {
+		err = -errno;
+		goto err_out;
+	}
+
+	/* pre-alloc memory and read all of BTF data */
+	data = malloc(sz);
+	if (!data) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+	if (fread(data, 1, sz, f) < sz) {
+		err = -EIO;
+		goto err_out;
+	}
+
+	/* finally parse BTF data */
+	btf = btf_new(data, sz, base_btf);
+
+err_out:
+	free(data);
+	if (f)
+		fclose(f);
+	return err ? ERR_PTR(err) : btf;
+}
+
+struct btf *btf__parse_raw(const char *path)
+{
+	return libbpf_ptr(btf_parse_raw(path, NULL));
+}
+
+struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf)
+{
+	return libbpf_ptr(btf_parse_raw(path, base_btf));
+}
+
+static struct btf *btf_parse(const char *path, struct btf *base_btf, struct btf_ext **btf_ext)
+{
+	struct btf *btf;
+	int err;
+
+	if (btf_ext)
+		*btf_ext = NULL;
+
+	btf = btf_parse_raw(path, base_btf);
+	err = libbpf_get_error(btf);
+	if (!err)
+		return btf;
+	if (err != -EPROTO)
+		return ERR_PTR(err);
+	return btf_parse_elf(path, base_btf, btf_ext);
+}
+
+struct btf *btf__parse(const char *path, struct btf_ext **btf_ext)
+{
+	return libbpf_ptr(btf_parse(path, NULL, btf_ext));
+}
+
+struct btf *btf__parse_split(const char *path, struct btf *base_btf)
+{
+	return libbpf_ptr(btf_parse(path, base_btf, NULL));
+}
+
+static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian);
+
+int btf_load_into_kernel(struct btf *btf, char *log_buf, size_t log_sz, __u32 log_level)
+{
+	LIBBPF_OPTS(bpf_btf_load_opts, opts);
+	__u32 buf_sz = 0, raw_size;
+	char *buf = NULL, *tmp;
+	void *raw_data;
+	int err = 0;
+
+	if (btf->fd >= 0)
+		return libbpf_err(-EEXIST);
+	if (log_sz && !log_buf)
+		return libbpf_err(-EINVAL);
+
+	/* cache native raw data representation */
+	raw_data = btf_get_raw_data(btf, &raw_size, false);
+	if (!raw_data) {
+		err = -ENOMEM;
+		goto done;
+	}
+	btf->raw_size = raw_size;
+	btf->raw_data = raw_data;
+
+retry_load:
+	/* if log_level is 0, we won't provide log_buf/log_size to the kernel,
+	 * initially. Only if BTF loading fails, we bump log_level to 1 and
+	 * retry, using either auto-allocated or custom log_buf. This way
+	 * non-NULL custom log_buf provides a buffer just in case, but hopes
+	 * for successful load and no need for log_buf.
+	 */
+	if (log_level) {
+		/* if caller didn't provide custom log_buf, we'll keep
+		 * allocating our own progressively bigger buffers for BTF
+		 * verification log
+		 */
+		if (!log_buf) {
+			buf_sz = max((__u32)BPF_LOG_BUF_SIZE, buf_sz * 2);
+			tmp = realloc(buf, buf_sz);
+			if (!tmp) {
+				err = -ENOMEM;
+				goto done;
+			}
+			buf = tmp;
+			buf[0] = '\0';
+		}
+
+		opts.log_buf = log_buf ? log_buf : buf;
+		opts.log_size = log_buf ? log_sz : buf_sz;
+		opts.log_level = log_level;
+	}
+
+	btf->fd = bpf_btf_load(raw_data, raw_size, &opts);
+	if (btf->fd < 0) {
+		/* time to turn on verbose mode and try again */
+		if (log_level == 0) {
+			log_level = 1;
+			goto retry_load;
+		}
+		/* only retry if caller didn't provide custom log_buf, but
+		 * make sure we can never overflow buf_sz
+		 */
+		if (!log_buf && errno == ENOSPC && buf_sz <= UINT_MAX / 2)
+			goto retry_load;
+
+		err = -errno;
+		pr_warn("BTF loading error: %d\n", err);
+		/* don't print out contents of custom log_buf */
+		if (!log_buf && buf[0])
+			pr_warn("-- BEGIN BTF LOAD LOG ---\n%s\n-- END BTF LOAD LOG --\n", buf);
+	}
+
+done:
+	free(buf);
+	return libbpf_err(err);
+}
+
+int btf__load_into_kernel(struct btf *btf)
+{
+	return btf_load_into_kernel(btf, NULL, 0, 0);
+}
+
+int btf__fd(const struct btf *btf)
+{
+	return btf->fd;
+}
+
+void btf__set_fd(struct btf *btf, int fd)
+{
+	btf->fd = fd;
+}
+
+static const void *btf_strs_data(const struct btf *btf)
+{
+	return btf->strs_data ? btf->strs_data : strset__data(btf->strs_set);
+}
+
+static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian)
+{
+	struct btf_header *hdr = btf->hdr;
+	struct btf_type *t;
+	void *data, *p;
+	__u32 data_sz;
+	int i;
+
+	data = swap_endian ? btf->raw_data_swapped : btf->raw_data;
+	if (data) {
+		*size = btf->raw_size;
+		return data;
+	}
+
+	data_sz = hdr->hdr_len + hdr->type_len + hdr->str_len;
+	data = calloc(1, data_sz);
+	if (!data)
+		return NULL;
+	p = data;
+
+	memcpy(p, hdr, hdr->hdr_len);
+	if (swap_endian)
+		btf_bswap_hdr(p);
+	p += hdr->hdr_len;
+
+	memcpy(p, btf->types_data, hdr->type_len);
+	if (swap_endian) {
+		for (i = 0; i < btf->nr_types; i++) {
+			t = p + btf->type_offs[i];
+			/* btf_bswap_type_rest() relies on native t->info, so
+			 * we swap base type info after we swapped all the
+			 * additional information
+			 */
+			if (btf_bswap_type_rest(t))
+				goto err_out;
+			btf_bswap_type_base(t);
+		}
+	}
+	p += hdr->type_len;
+
+	memcpy(p, btf_strs_data(btf), hdr->str_len);
+	p += hdr->str_len;
+
+	*size = data_sz;
+	return data;
+err_out:
+	free(data);
+	return NULL;
+}
+
+const void *btf__raw_data(const struct btf *btf_ro, __u32 *size)
+{
+	struct btf *btf = (struct btf *)btf_ro;
+	__u32 data_sz;
+	void *data;
+
+	data = btf_get_raw_data(btf, &data_sz, btf->swapped_endian);
+	if (!data)
+		return errno = ENOMEM, NULL;
+
+	btf->raw_size = data_sz;
+	if (btf->swapped_endian)
+		btf->raw_data_swapped = data;
+	else
+		btf->raw_data = data;
+	*size = data_sz;
+	return data;
+}
+
+__attribute__((alias("btf__raw_data")))
+const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
+
+const char *btf__str_by_offset(const struct btf *btf, __u32 offset)
+{
+	if (offset < btf->start_str_off)
+		return btf__str_by_offset(btf->base_btf, offset);
+	else if (offset - btf->start_str_off < btf->hdr->str_len)
+		return btf_strs_data(btf) + (offset - btf->start_str_off);
+	else
+		return errno = EINVAL, NULL;
+}
+
+const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
+{
+	return btf__str_by_offset(btf, offset);
+}
+
+struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf)
+{
+	struct bpf_btf_info btf_info;
+	__u32 len = sizeof(btf_info);
+	__u32 last_size;
+	struct btf *btf;
+	void *ptr;
+	int err;
+
+	/* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so
+	 * let's start with a sane default - 4KiB here - and resize it only if
+	 * bpf_obj_get_info_by_fd() needs a bigger buffer.
+	 */
+	last_size = 4096;
+	ptr = malloc(last_size);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	memset(&btf_info, 0, sizeof(btf_info));
+	btf_info.btf = ptr_to_u64(ptr);
+	btf_info.btf_size = last_size;
+	err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
+
+	if (!err && btf_info.btf_size > last_size) {
+		void *temp_ptr;
+
+		last_size = btf_info.btf_size;
+		temp_ptr = realloc(ptr, last_size);
+		if (!temp_ptr) {
+			btf = ERR_PTR(-ENOMEM);
+			goto exit_free;
+		}
+		ptr = temp_ptr;
+
+		len = sizeof(btf_info);
+		memset(&btf_info, 0, sizeof(btf_info));
+		btf_info.btf = ptr_to_u64(ptr);
+		btf_info.btf_size = last_size;
+
+		err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
+	}
+
+	if (err || btf_info.btf_size > last_size) {
+		btf = err ? ERR_PTR(-errno) : ERR_PTR(-E2BIG);
+		goto exit_free;
+	}
+
+	btf = btf_new(ptr, btf_info.btf_size, base_btf);
+
+exit_free:
+	free(ptr);
+	return btf;
+}
+
+struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf)
+{
+	struct btf *btf;
+	int btf_fd;
+
+	btf_fd = bpf_btf_get_fd_by_id(id);
+	if (btf_fd < 0)
+		return libbpf_err_ptr(-errno);
+
+	btf = btf_get_from_fd(btf_fd, base_btf);
+	close(btf_fd);
+
+	return libbpf_ptr(btf);
+}
+
+struct btf *btf__load_from_kernel_by_id(__u32 id)
+{
+	return btf__load_from_kernel_by_id_split(id, NULL);
+}
+
+static void btf_invalidate_raw_data(struct btf *btf)
+{
+	if (btf->raw_data) {
+		free(btf->raw_data);
+		btf->raw_data = NULL;
+	}
+	if (btf->raw_data_swapped) {
+		free(btf->raw_data_swapped);
+		btf->raw_data_swapped = NULL;
+	}
+}
+
+/* Ensure BTF is ready to be modified (by splitting into a three memory
+ * regions for header, types, and strings). Also invalidate cached
+ * raw_data, if any.
+ */
+static int btf_ensure_modifiable(struct btf *btf)
+{
+	void *hdr, *types;
+	struct strset *set = NULL;
+	int err = -ENOMEM;
+
+	if (btf_is_modifiable(btf)) {
+		/* any BTF modification invalidates raw_data */
+		btf_invalidate_raw_data(btf);
+		return 0;
+	}
+
+	/* split raw data into three memory regions */
+	hdr = malloc(btf->hdr->hdr_len);
+	types = malloc(btf->hdr->type_len);
+	if (!hdr || !types)
+		goto err_out;
+
+	memcpy(hdr, btf->hdr, btf->hdr->hdr_len);
+	memcpy(types, btf->types_data, btf->hdr->type_len);
+
+	/* build lookup index for all strings */
+	set = strset__new(BTF_MAX_STR_OFFSET, btf->strs_data, btf->hdr->str_len);
+	if (IS_ERR(set)) {
+		err = PTR_ERR(set);
+		goto err_out;
+	}
+
+	/* only when everything was successful, update internal state */
+	btf->hdr = hdr;
+	btf->types_data = types;
+	btf->types_data_cap = btf->hdr->type_len;
+	btf->strs_data = NULL;
+	btf->strs_set = set;
+	/* if BTF was created from scratch, all strings are guaranteed to be
+	 * unique and deduplicated
+	 */
+	if (btf->hdr->str_len == 0)
+		btf->strs_deduped = true;
+	if (!btf->base_btf && btf->hdr->str_len == 1)
+		btf->strs_deduped = true;
+
+	/* invalidate raw_data representation */
+	btf_invalidate_raw_data(btf);
+
+	return 0;
+
+err_out:
+	strset__free(set);
+	free(hdr);
+	free(types);
+	return err;
+}
+
+/* Find an offset in BTF string section that corresponds to a given string *s*.
+ * Returns:
+ *   - >0 offset into string section, if string is found;
+ *   - -ENOENT, if string is not in the string section;
+ *   - <0, on any other error.
+ */
+int btf__find_str(struct btf *btf, const char *s)
+{
+	int off;
+
+	if (btf->base_btf) {
+		off = btf__find_str(btf->base_btf, s);
+		if (off != -ENOENT)
+			return off;
+	}
+
+	/* BTF needs to be in a modifiable state to build string lookup index */
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	off = strset__find_str(btf->strs_set, s);
+	if (off < 0)
+		return libbpf_err(off);
+
+	return btf->start_str_off + off;
+}
+
+/* Add a string s to the BTF string section.
+ * Returns:
+ *   - > 0 offset into string section, on success;
+ *   - < 0, on error.
+ */
+int btf__add_str(struct btf *btf, const char *s)
+{
+	int off;
+
+	if (btf->base_btf) {
+		off = btf__find_str(btf->base_btf, s);
+		if (off != -ENOENT)
+			return off;
+	}
+
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	off = strset__add_str(btf->strs_set, s);
+	if (off < 0)
+		return libbpf_err(off);
+
+	btf->hdr->str_len = strset__data_size(btf->strs_set);
+
+	return btf->start_str_off + off;
+}
+
+static void *btf_add_type_mem(struct btf *btf, size_t add_sz)
+{
+	return libbpf_add_mem(&btf->types_data, &btf->types_data_cap, 1,
+			      btf->hdr->type_len, UINT_MAX, add_sz);
+}
+
+static void btf_type_inc_vlen(struct btf_type *t)
+{
+	t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, btf_kflag(t));
+}
+
+static int btf_commit_type(struct btf *btf, int data_sz)
+{
+	int err;
+
+	err = btf_add_type_idx_entry(btf, btf->hdr->type_len);
+	if (err)
+		return libbpf_err(err);
+
+	btf->hdr->type_len += data_sz;
+	btf->hdr->str_off += data_sz;
+	btf->nr_types++;
+	return btf->start_id + btf->nr_types - 1;
+}
+
+struct btf_pipe {
+	const struct btf *src;
+	struct btf *dst;
+	struct hashmap *str_off_map; /* map string offsets from src to dst */
+};
+
+static int btf_rewrite_str(__u32 *str_off, void *ctx)
+{
+	struct btf_pipe *p = ctx;
+	long mapped_off;
+	int off, err;
+
+	if (!*str_off) /* nothing to do for empty strings */
+		return 0;
+
+	if (p->str_off_map &&
+	    hashmap__find(p->str_off_map, *str_off, &mapped_off)) {
+		*str_off = mapped_off;
+		return 0;
+	}
+
+	off = btf__add_str(p->dst, btf__str_by_offset(p->src, *str_off));
+	if (off < 0)
+		return off;
+
+	/* Remember string mapping from src to dst.  It avoids
+	 * performing expensive string comparisons.
+	 */
+	if (p->str_off_map) {
+		err = hashmap__append(p->str_off_map, *str_off, off);
+		if (err)
+			return err;
+	}
+
+	*str_off = off;
+	return 0;
+}
+
+int btf__add_type(struct btf *btf, const struct btf *src_btf, const struct btf_type *src_type)
+{
+	struct btf_pipe p = { .src = src_btf, .dst = btf };
+	struct btf_type *t;
+	int sz, err;
+
+	sz = btf_type_size(src_type);
+	if (sz < 0)
+		return libbpf_err(sz);
+
+	/* deconstruct BTF, if necessary, and invalidate raw_data */
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	memcpy(t, src_type, sz);
+
+	err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
+	if (err)
+		return libbpf_err(err);
+
+	return btf_commit_type(btf, sz);
+}
+
+static int btf_rewrite_type_ids(__u32 *type_id, void *ctx)
+{
+	struct btf *btf = ctx;
+
+	if (!*type_id) /* nothing to do for VOID references */
+		return 0;
+
+	/* we haven't updated btf's type count yet, so
+	 * btf->start_id + btf->nr_types - 1 is the type ID offset we should
+	 * add to all newly added BTF types
+	 */
+	*type_id += btf->start_id + btf->nr_types - 1;
+	return 0;
+}
+
+static size_t btf_dedup_identity_hash_fn(long key, void *ctx);
+static bool btf_dedup_equal_fn(long k1, long k2, void *ctx);
+
+int btf__add_btf(struct btf *btf, const struct btf *src_btf)
+{
+	struct btf_pipe p = { .src = src_btf, .dst = btf };
+	int data_sz, sz, cnt, i, err, old_strs_len;
+	__u32 *off;
+	void *t;
+
+	/* appending split BTF isn't supported yet */
+	if (src_btf->base_btf)
+		return libbpf_err(-ENOTSUP);
+
+	/* deconstruct BTF, if necessary, and invalidate raw_data */
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	/* remember original strings section size if we have to roll back
+	 * partial strings section changes
+	 */
+	old_strs_len = btf->hdr->str_len;
+
+	data_sz = src_btf->hdr->type_len;
+	cnt = btf__type_cnt(src_btf) - 1;
+
+	/* pre-allocate enough memory for new types */
+	t = btf_add_type_mem(btf, data_sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	/* pre-allocate enough memory for type offset index for new types */
+	off = btf_add_type_offs_mem(btf, cnt);
+	if (!off)
+		return libbpf_err(-ENOMEM);
+
+	/* Map the string offsets from src_btf to the offsets from btf to improve performance */
+	p.str_off_map = hashmap__new(btf_dedup_identity_hash_fn, btf_dedup_equal_fn, NULL);
+	if (IS_ERR(p.str_off_map))
+		return libbpf_err(-ENOMEM);
+
+	/* bulk copy types data for all types from src_btf */
+	memcpy(t, src_btf->types_data, data_sz);
+
+	for (i = 0; i < cnt; i++) {
+		sz = btf_type_size(t);
+		if (sz < 0) {
+			/* unlikely, has to be corrupted src_btf */
+			err = sz;
+			goto err_out;
+		}
+
+		/* fill out type ID to type offset mapping for lookups by type ID */
+		*off = t - btf->types_data;
+
+		/* add, dedup, and remap strings referenced by this BTF type */
+		err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
+		if (err)
+			goto err_out;
+
+		/* remap all type IDs referenced from this BTF type */
+		err = btf_type_visit_type_ids(t, btf_rewrite_type_ids, btf);
+		if (err)
+			goto err_out;
+
+		/* go to next type data and type offset index entry */
+		t += sz;
+		off++;
+	}
+
+	/* Up until now any of the copied type data was effectively invisible,
+	 * so if we exited early before this point due to error, BTF would be
+	 * effectively unmodified. There would be extra internal memory
+	 * pre-allocated, but it would not be available for querying.  But now
+	 * that we've copied and rewritten all the data successfully, we can
+	 * update type count and various internal offsets and sizes to
+	 * "commit" the changes and made them visible to the outside world.
+	 */
+	btf->hdr->type_len += data_sz;
+	btf->hdr->str_off += data_sz;
+	btf->nr_types += cnt;
+
+	hashmap__free(p.str_off_map);
+
+	/* return type ID of the first added BTF type */
+	return btf->start_id + btf->nr_types - cnt;
+err_out:
+	/* zero out preallocated memory as if it was just allocated with
+	 * libbpf_add_mem()
+	 */
+	memset(btf->types_data + btf->hdr->type_len, 0, data_sz);
+	memset(btf->strs_data + old_strs_len, 0, btf->hdr->str_len - old_strs_len);
+
+	/* and now restore original strings section size; types data size
+	 * wasn't modified, so doesn't need restoring, see big comment above
+	 */
+	btf->hdr->str_len = old_strs_len;
+
+	hashmap__free(p.str_off_map);
+
+	return libbpf_err(err);
+}
+
+/*
+ * Append new BTF_KIND_INT type with:
+ *   - *name* - non-empty, non-NULL type name;
+ *   - *sz* - power-of-2 (1, 2, 4, ..) size of the type, in bytes;
+ *   - encoding is a combination of BTF_INT_SIGNED, BTF_INT_CHAR, BTF_INT_BOOL.
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding)
+{
+	struct btf_type *t;
+	int sz, name_off;
+
+	/* non-empty name */
+	if (!name || !name[0])
+		return libbpf_err(-EINVAL);
+	/* byte_sz must be power of 2 */
+	if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 16)
+		return libbpf_err(-EINVAL);
+	if (encoding & ~(BTF_INT_SIGNED | BTF_INT_CHAR | BTF_INT_BOOL))
+		return libbpf_err(-EINVAL);
+
+	/* deconstruct BTF, if necessary, and invalidate raw_data */
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_type) + sizeof(int);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	/* if something goes wrong later, we might end up with an extra string,
+	 * but that shouldn't be a problem, because BTF can't be constructed
+	 * completely anyway and will most probably be just discarded
+	 */
+	name_off = btf__add_str(btf, name);
+	if (name_off < 0)
+		return name_off;
+
+	t->name_off = name_off;
+	t->info = btf_type_info(BTF_KIND_INT, 0, 0);
+	t->size = byte_sz;
+	/* set INT info, we don't allow setting legacy bit offset/size */
+	*(__u32 *)(t + 1) = (encoding << 24) | (byte_sz * 8);
+
+	return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new BTF_KIND_FLOAT type with:
+ *   - *name* - non-empty, non-NULL type name;
+ *   - *sz* - size of the type, in bytes;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_float(struct btf *btf, const char *name, size_t byte_sz)
+{
+	struct btf_type *t;
+	int sz, name_off;
+
+	/* non-empty name */
+	if (!name || !name[0])
+		return libbpf_err(-EINVAL);
+
+	/* byte_sz must be one of the explicitly allowed values */
+	if (byte_sz != 2 && byte_sz != 4 && byte_sz != 8 && byte_sz != 12 &&
+	    byte_sz != 16)
+		return libbpf_err(-EINVAL);
+
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_type);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	name_off = btf__add_str(btf, name);
+	if (name_off < 0)
+		return name_off;
+
+	t->name_off = name_off;
+	t->info = btf_type_info(BTF_KIND_FLOAT, 0, 0);
+	t->size = byte_sz;
+
+	return btf_commit_type(btf, sz);
+}
+
+/* it's completely legal to append BTF types with type IDs pointing forward to
+ * types that haven't been appended yet, so we only make sure that id looks
+ * sane, we can't guarantee that ID will always be valid
+ */
+static int validate_type_id(int id)
+{
+	if (id < 0 || id > BTF_MAX_NR_TYPES)
+		return -EINVAL;
+	return 0;
+}
+
+/* generic append function for PTR, TYPEDEF, CONST/VOLATILE/RESTRICT */
+static int btf_add_ref_kind(struct btf *btf, int kind, const char *name, int ref_type_id)
+{
+	struct btf_type *t;
+	int sz, name_off = 0;
+
+	if (validate_type_id(ref_type_id))
+		return libbpf_err(-EINVAL);
+
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_type);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	if (name && name[0]) {
+		name_off = btf__add_str(btf, name);
+		if (name_off < 0)
+			return name_off;
+	}
+
+	t->name_off = name_off;
+	t->info = btf_type_info(kind, 0, 0);
+	t->type = ref_type_id;
+
+	return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new BTF_KIND_PTR type with:
+ *   - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_ptr(struct btf *btf, int ref_type_id)
+{
+	return btf_add_ref_kind(btf, BTF_KIND_PTR, NULL, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_ARRAY type with:
+ *   - *index_type_id* - type ID of the type describing array index;
+ *   - *elem_type_id* - type ID of the type describing array element;
+ *   - *nr_elems* - the size of the array;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_array(struct btf *btf, int index_type_id, int elem_type_id, __u32 nr_elems)
+{
+	struct btf_type *t;
+	struct btf_array *a;
+	int sz;
+
+	if (validate_type_id(index_type_id) || validate_type_id(elem_type_id))
+		return libbpf_err(-EINVAL);
+
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_type) + sizeof(struct btf_array);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	t->name_off = 0;
+	t->info = btf_type_info(BTF_KIND_ARRAY, 0, 0);
+	t->size = 0;
+
+	a = btf_array(t);
+	a->type = elem_type_id;
+	a->index_type = index_type_id;
+	a->nelems = nr_elems;
+
+	return btf_commit_type(btf, sz);
+}
+
+/* generic STRUCT/UNION append function */
+static int btf_add_composite(struct btf *btf, int kind, const char *name, __u32 bytes_sz)
+{
+	struct btf_type *t;
+	int sz, name_off = 0;
+
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_type);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	if (name && name[0]) {
+		name_off = btf__add_str(btf, name);
+		if (name_off < 0)
+			return name_off;
+	}
+
+	/* start out with vlen=0 and no kflag; this will be adjusted when
+	 * adding each member
+	 */
+	t->name_off = name_off;
+	t->info = btf_type_info(kind, 0, 0);
+	t->size = bytes_sz;
+
+	return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new BTF_KIND_STRUCT type with:
+ *   - *name* - name of the struct, can be NULL or empty for anonymous structs;
+ *   - *byte_sz* - size of the struct, in bytes;
+ *
+ * Struct initially has no fields in it. Fields can be added by
+ * btf__add_field() right after btf__add_struct() succeeds.
+ *
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_struct(struct btf *btf, const char *name, __u32 byte_sz)
+{
+	return btf_add_composite(btf, BTF_KIND_STRUCT, name, byte_sz);
+}
+
+/*
+ * Append new BTF_KIND_UNION type with:
+ *   - *name* - name of the union, can be NULL or empty for anonymous union;
+ *   - *byte_sz* - size of the union, in bytes;
+ *
+ * Union initially has no fields in it. Fields can be added by
+ * btf__add_field() right after btf__add_union() succeeds. All fields
+ * should have *bit_offset* of 0.
+ *
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_union(struct btf *btf, const char *name, __u32 byte_sz)
+{
+	return btf_add_composite(btf, BTF_KIND_UNION, name, byte_sz);
+}
+
+static struct btf_type *btf_last_type(struct btf *btf)
+{
+	return btf_type_by_id(btf, btf__type_cnt(btf) - 1);
+}
+
+/*
+ * Append new field for the current STRUCT/UNION type with:
+ *   - *name* - name of the field, can be NULL or empty for anonymous field;
+ *   - *type_id* - type ID for the type describing field type;
+ *   - *bit_offset* - bit offset of the start of the field within struct/union;
+ *   - *bit_size* - bit size of a bitfield, 0 for non-bitfield fields;
+ * Returns:
+ *   -  0, on success;
+ *   - <0, on error.
+ */
+int btf__add_field(struct btf *btf, const char *name, int type_id,
+		   __u32 bit_offset, __u32 bit_size)
+{
+	struct btf_type *t;
+	struct btf_member *m;
+	bool is_bitfield;
+	int sz, name_off = 0;
+
+	/* last type should be union/struct */
+	if (btf->nr_types == 0)
+		return libbpf_err(-EINVAL);
+	t = btf_last_type(btf);
+	if (!btf_is_composite(t))
+		return libbpf_err(-EINVAL);
+
+	if (validate_type_id(type_id))
+		return libbpf_err(-EINVAL);
+	/* best-effort bit field offset/size enforcement */
+	is_bitfield = bit_size || (bit_offset % 8 != 0);
+	if (is_bitfield && (bit_size == 0 || bit_size > 255 || bit_offset > 0xffffff))
+		return libbpf_err(-EINVAL);
+
+	/* only offset 0 is allowed for unions */
+	if (btf_is_union(t) && bit_offset)
+		return libbpf_err(-EINVAL);
+
+	/* decompose and invalidate raw data */
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_member);
+	m = btf_add_type_mem(btf, sz);
+	if (!m)
+		return libbpf_err(-ENOMEM);
+
+	if (name && name[0]) {
+		name_off = btf__add_str(btf, name);
+		if (name_off < 0)
+			return name_off;
+	}
+
+	m->name_off = name_off;
+	m->type = type_id;
+	m->offset = bit_offset | (bit_size << 24);
+
+	/* btf_add_type_mem can invalidate t pointer */
+	t = btf_last_type(btf);
+	/* update parent type's vlen and kflag */
+	t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, is_bitfield || btf_kflag(t));
+
+	btf->hdr->type_len += sz;
+	btf->hdr->str_off += sz;
+	return 0;
+}
+
+static int btf_add_enum_common(struct btf *btf, const char *name, __u32 byte_sz,
+			       bool is_signed, __u8 kind)
+{
+	struct btf_type *t;
+	int sz, name_off = 0;
+
+	/* byte_sz must be power of 2 */
+	if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 8)
+		return libbpf_err(-EINVAL);
+
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_type);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	if (name && name[0]) {
+		name_off = btf__add_str(btf, name);
+		if (name_off < 0)
+			return name_off;
+	}
+
+	/* start out with vlen=0; it will be adjusted when adding enum values */
+	t->name_off = name_off;
+	t->info = btf_type_info(kind, 0, is_signed);
+	t->size = byte_sz;
+
+	return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new BTF_KIND_ENUM type with:
+ *   - *name* - name of the enum, can be NULL or empty for anonymous enums;
+ *   - *byte_sz* - size of the enum, in bytes.
+ *
+ * Enum initially has no enum values in it (and corresponds to enum forward
+ * declaration). Enumerator values can be added by btf__add_enum_value()
+ * immediately after btf__add_enum() succeeds.
+ *
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_enum(struct btf *btf, const char *name, __u32 byte_sz)
+{
+	/*
+	 * set the signedness to be unsigned, it will change to signed
+	 * if any later enumerator is negative.
+	 */
+	return btf_add_enum_common(btf, name, byte_sz, false, BTF_KIND_ENUM);
+}
+
+/*
+ * Append new enum value for the current ENUM type with:
+ *   - *name* - name of the enumerator value, can't be NULL or empty;
+ *   - *value* - integer value corresponding to enum value *name*;
+ * Returns:
+ *   -  0, on success;
+ *   - <0, on error.
+ */
+int btf__add_enum_value(struct btf *btf, const char *name, __s64 value)
+{
+	struct btf_type *t;
+	struct btf_enum *v;
+	int sz, name_off;
+
+	/* last type should be BTF_KIND_ENUM */
+	if (btf->nr_types == 0)
+		return libbpf_err(-EINVAL);
+	t = btf_last_type(btf);
+	if (!btf_is_enum(t))
+		return libbpf_err(-EINVAL);
+
+	/* non-empty name */
+	if (!name || !name[0])
+		return libbpf_err(-EINVAL);
+	if (value < INT_MIN || value > UINT_MAX)
+		return libbpf_err(-E2BIG);
+
+	/* decompose and invalidate raw data */
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_enum);
+	v = btf_add_type_mem(btf, sz);
+	if (!v)
+		return libbpf_err(-ENOMEM);
+
+	name_off = btf__add_str(btf, name);
+	if (name_off < 0)
+		return name_off;
+
+	v->name_off = name_off;
+	v->val = value;
+
+	/* update parent type's vlen */
+	t = btf_last_type(btf);
+	btf_type_inc_vlen(t);
+
+	/* if negative value, set signedness to signed */
+	if (value < 0)
+		t->info = btf_type_info(btf_kind(t), btf_vlen(t), true);
+
+	btf->hdr->type_len += sz;
+	btf->hdr->str_off += sz;
+	return 0;
+}
+
+/*
+ * Append new BTF_KIND_ENUM64 type with:
+ *   - *name* - name of the enum, can be NULL or empty for anonymous enums;
+ *   - *byte_sz* - size of the enum, in bytes.
+ *   - *is_signed* - whether the enum values are signed or not;
+ *
+ * Enum initially has no enum values in it (and corresponds to enum forward
+ * declaration). Enumerator values can be added by btf__add_enum64_value()
+ * immediately after btf__add_enum64() succeeds.
+ *
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_enum64(struct btf *btf, const char *name, __u32 byte_sz,
+		    bool is_signed)
+{
+	return btf_add_enum_common(btf, name, byte_sz, is_signed,
+				   BTF_KIND_ENUM64);
+}
+
+/*
+ * Append new enum value for the current ENUM64 type with:
+ *   - *name* - name of the enumerator value, can't be NULL or empty;
+ *   - *value* - integer value corresponding to enum value *name*;
+ * Returns:
+ *   -  0, on success;
+ *   - <0, on error.
+ */
+int btf__add_enum64_value(struct btf *btf, const char *name, __u64 value)
+{
+	struct btf_enum64 *v;
+	struct btf_type *t;
+	int sz, name_off;
+
+	/* last type should be BTF_KIND_ENUM64 */
+	if (btf->nr_types == 0)
+		return libbpf_err(-EINVAL);
+	t = btf_last_type(btf);
+	if (!btf_is_enum64(t))
+		return libbpf_err(-EINVAL);
+
+	/* non-empty name */
+	if (!name || !name[0])
+		return libbpf_err(-EINVAL);
+
+	/* decompose and invalidate raw data */
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_enum64);
+	v = btf_add_type_mem(btf, sz);
+	if (!v)
+		return libbpf_err(-ENOMEM);
+
+	name_off = btf__add_str(btf, name);
+	if (name_off < 0)
+		return name_off;
+
+	v->name_off = name_off;
+	v->val_lo32 = (__u32)value;
+	v->val_hi32 = value >> 32;
+
+	/* update parent type's vlen */
+	t = btf_last_type(btf);
+	btf_type_inc_vlen(t);
+
+	btf->hdr->type_len += sz;
+	btf->hdr->str_off += sz;
+	return 0;
+}
+
+/*
+ * Append new BTF_KIND_FWD type with:
+ *   - *name*, non-empty/non-NULL name;
+ *   - *fwd_kind*, kind of forward declaration, one of BTF_FWD_STRUCT,
+ *     BTF_FWD_UNION, or BTF_FWD_ENUM;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_fwd(struct btf *btf, const char *name, enum btf_fwd_kind fwd_kind)
+{
+	if (!name || !name[0])
+		return libbpf_err(-EINVAL);
+
+	switch (fwd_kind) {
+	case BTF_FWD_STRUCT:
+	case BTF_FWD_UNION: {
+		struct btf_type *t;
+		int id;
+
+		id = btf_add_ref_kind(btf, BTF_KIND_FWD, name, 0);
+		if (id <= 0)
+			return id;
+		t = btf_type_by_id(btf, id);
+		t->info = btf_type_info(BTF_KIND_FWD, 0, fwd_kind == BTF_FWD_UNION);
+		return id;
+	}
+	case BTF_FWD_ENUM:
+		/* enum forward in BTF currently is just an enum with no enum
+		 * values; we also assume a standard 4-byte size for it
+		 */
+		return btf__add_enum(btf, name, sizeof(int));
+	default:
+		return libbpf_err(-EINVAL);
+	}
+}
+
+/*
+ * Append new BTF_KING_TYPEDEF type with:
+ *   - *name*, non-empty/non-NULL name;
+ *   - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_typedef(struct btf *btf, const char *name, int ref_type_id)
+{
+	if (!name || !name[0])
+		return libbpf_err(-EINVAL);
+
+	return btf_add_ref_kind(btf, BTF_KIND_TYPEDEF, name, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_VOLATILE type with:
+ *   - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_volatile(struct btf *btf, int ref_type_id)
+{
+	return btf_add_ref_kind(btf, BTF_KIND_VOLATILE, NULL, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_CONST type with:
+ *   - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_const(struct btf *btf, int ref_type_id)
+{
+	return btf_add_ref_kind(btf, BTF_KIND_CONST, NULL, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_RESTRICT type with:
+ *   - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_restrict(struct btf *btf, int ref_type_id)
+{
+	return btf_add_ref_kind(btf, BTF_KIND_RESTRICT, NULL, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_TYPE_TAG type with:
+ *   - *value*, non-empty/non-NULL tag value;
+ *   - *ref_type_id* - referenced type ID, it might not exist yet;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_type_tag(struct btf *btf, const char *value, int ref_type_id)
+{
+	if (!value || !value[0])
+		return libbpf_err(-EINVAL);
+
+	return btf_add_ref_kind(btf, BTF_KIND_TYPE_TAG, value, ref_type_id);
+}
+
+/*
+ * Append new BTF_KIND_FUNC type with:
+ *   - *name*, non-empty/non-NULL name;
+ *   - *proto_type_id* - FUNC_PROTO's type ID, it might not exist yet;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_func(struct btf *btf, const char *name,
+		  enum btf_func_linkage linkage, int proto_type_id)
+{
+	int id;
+
+	if (!name || !name[0])
+		return libbpf_err(-EINVAL);
+	if (linkage != BTF_FUNC_STATIC && linkage != BTF_FUNC_GLOBAL &&
+	    linkage != BTF_FUNC_EXTERN)
+		return libbpf_err(-EINVAL);
+
+	id = btf_add_ref_kind(btf, BTF_KIND_FUNC, name, proto_type_id);
+	if (id > 0) {
+		struct btf_type *t = btf_type_by_id(btf, id);
+
+		t->info = btf_type_info(BTF_KIND_FUNC, linkage, 0);
+	}
+	return libbpf_err(id);
+}
+
+/*
+ * Append new BTF_KIND_FUNC_PROTO with:
+ *   - *ret_type_id* - type ID for return result of a function.
+ *
+ * Function prototype initially has no arguments, but they can be added by
+ * btf__add_func_param() one by one, immediately after
+ * btf__add_func_proto() succeeded.
+ *
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_func_proto(struct btf *btf, int ret_type_id)
+{
+	struct btf_type *t;
+	int sz;
+
+	if (validate_type_id(ret_type_id))
+		return libbpf_err(-EINVAL);
+
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_type);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	/* start out with vlen=0; this will be adjusted when adding enum
+	 * values, if necessary
+	 */
+	t->name_off = 0;
+	t->info = btf_type_info(BTF_KIND_FUNC_PROTO, 0, 0);
+	t->type = ret_type_id;
+
+	return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new function parameter for current FUNC_PROTO type with:
+ *   - *name* - parameter name, can be NULL or empty;
+ *   - *type_id* - type ID describing the type of the parameter.
+ * Returns:
+ *   -  0, on success;
+ *   - <0, on error.
+ */
+int btf__add_func_param(struct btf *btf, const char *name, int type_id)
+{
+	struct btf_type *t;
+	struct btf_param *p;
+	int sz, name_off = 0;
+
+	if (validate_type_id(type_id))
+		return libbpf_err(-EINVAL);
+
+	/* last type should be BTF_KIND_FUNC_PROTO */
+	if (btf->nr_types == 0)
+		return libbpf_err(-EINVAL);
+	t = btf_last_type(btf);
+	if (!btf_is_func_proto(t))
+		return libbpf_err(-EINVAL);
+
+	/* decompose and invalidate raw data */
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_param);
+	p = btf_add_type_mem(btf, sz);
+	if (!p)
+		return libbpf_err(-ENOMEM);
+
+	if (name && name[0]) {
+		name_off = btf__add_str(btf, name);
+		if (name_off < 0)
+			return name_off;
+	}
+
+	p->name_off = name_off;
+	p->type = type_id;
+
+	/* update parent type's vlen */
+	t = btf_last_type(btf);
+	btf_type_inc_vlen(t);
+
+	btf->hdr->type_len += sz;
+	btf->hdr->str_off += sz;
+	return 0;
+}
+
+/*
+ * Append new BTF_KIND_VAR type with:
+ *   - *name* - non-empty/non-NULL name;
+ *   - *linkage* - variable linkage, one of BTF_VAR_STATIC,
+ *     BTF_VAR_GLOBAL_ALLOCATED, or BTF_VAR_GLOBAL_EXTERN;
+ *   - *type_id* - type ID of the type describing the type of the variable.
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_var(struct btf *btf, const char *name, int linkage, int type_id)
+{
+	struct btf_type *t;
+	struct btf_var *v;
+	int sz, name_off;
+
+	/* non-empty name */
+	if (!name || !name[0])
+		return libbpf_err(-EINVAL);
+	if (linkage != BTF_VAR_STATIC && linkage != BTF_VAR_GLOBAL_ALLOCATED &&
+	    linkage != BTF_VAR_GLOBAL_EXTERN)
+		return libbpf_err(-EINVAL);
+	if (validate_type_id(type_id))
+		return libbpf_err(-EINVAL);
+
+	/* deconstruct BTF, if necessary, and invalidate raw_data */
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_type) + sizeof(struct btf_var);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	name_off = btf__add_str(btf, name);
+	if (name_off < 0)
+		return name_off;
+
+	t->name_off = name_off;
+	t->info = btf_type_info(BTF_KIND_VAR, 0, 0);
+	t->type = type_id;
+
+	v = btf_var(t);
+	v->linkage = linkage;
+
+	return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new BTF_KIND_DATASEC type with:
+ *   - *name* - non-empty/non-NULL name;
+ *   - *byte_sz* - data section size, in bytes.
+ *
+ * Data section is initially empty. Variables info can be added with
+ * btf__add_datasec_var_info() calls, after btf__add_datasec() succeeds.
+ *
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz)
+{
+	struct btf_type *t;
+	int sz, name_off;
+
+	/* non-empty name */
+	if (!name || !name[0])
+		return libbpf_err(-EINVAL);
+
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_type);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	name_off = btf__add_str(btf, name);
+	if (name_off < 0)
+		return name_off;
+
+	/* start with vlen=0, which will be update as var_secinfos are added */
+	t->name_off = name_off;
+	t->info = btf_type_info(BTF_KIND_DATASEC, 0, 0);
+	t->size = byte_sz;
+
+	return btf_commit_type(btf, sz);
+}
+
+/*
+ * Append new data section variable information entry for current DATASEC type:
+ *   - *var_type_id* - type ID, describing type of the variable;
+ *   - *offset* - variable offset within data section, in bytes;
+ *   - *byte_sz* - variable size, in bytes.
+ *
+ * Returns:
+ *   -  0, on success;
+ *   - <0, on error.
+ */
+int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __u32 byte_sz)
+{
+	struct btf_type *t;
+	struct btf_var_secinfo *v;
+	int sz;
+
+	/* last type should be BTF_KIND_DATASEC */
+	if (btf->nr_types == 0)
+		return libbpf_err(-EINVAL);
+	t = btf_last_type(btf);
+	if (!btf_is_datasec(t))
+		return libbpf_err(-EINVAL);
+
+	if (validate_type_id(var_type_id))
+		return libbpf_err(-EINVAL);
+
+	/* decompose and invalidate raw data */
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_var_secinfo);
+	v = btf_add_type_mem(btf, sz);
+	if (!v)
+		return libbpf_err(-ENOMEM);
+
+	v->type = var_type_id;
+	v->offset = offset;
+	v->size = byte_sz;
+
+	/* update parent type's vlen */
+	t = btf_last_type(btf);
+	btf_type_inc_vlen(t);
+
+	btf->hdr->type_len += sz;
+	btf->hdr->str_off += sz;
+	return 0;
+}
+
+/*
+ * Append new BTF_KIND_DECL_TAG type with:
+ *   - *value* - non-empty/non-NULL string;
+ *   - *ref_type_id* - referenced type ID, it might not exist yet;
+ *   - *component_idx* - -1 for tagging reference type, otherwise struct/union
+ *     member or function argument index;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
+		 int component_idx)
+{
+	struct btf_type *t;
+	int sz, value_off;
+
+	if (!value || !value[0] || component_idx < -1)
+		return libbpf_err(-EINVAL);
+
+	if (validate_type_id(ref_type_id))
+		return libbpf_err(-EINVAL);
+
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_type) + sizeof(struct btf_decl_tag);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	value_off = btf__add_str(btf, value);
+	if (value_off < 0)
+		return value_off;
+
+	t->name_off = value_off;
+	t->info = btf_type_info(BTF_KIND_DECL_TAG, 0, false);
+	t->type = ref_type_id;
+	btf_decl_tag(t)->component_idx = component_idx;
+
+	return btf_commit_type(btf, sz);
+}
+
+struct btf_ext_sec_setup_param {
+	__u32 off;
+	__u32 len;
+	__u32 min_rec_size;
+	struct btf_ext_info *ext_info;
+	const char *desc;
+};
+
+static int btf_ext_setup_info(struct btf_ext *btf_ext,
+			      struct btf_ext_sec_setup_param *ext_sec)
+{
+	const struct btf_ext_info_sec *sinfo;
+	struct btf_ext_info *ext_info;
+	__u32 info_left, record_size;
+	size_t sec_cnt = 0;
+	/* The start of the info sec (including the __u32 record_size). */
+	void *info;
+
+	if (ext_sec->len == 0)
+		return 0;
+
+	if (ext_sec->off & 0x03) {
+		pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
+		     ext_sec->desc);
+		return -EINVAL;
+	}
+
+	info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;
+	info_left = ext_sec->len;
+
+	if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {
+		pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
+			 ext_sec->desc, ext_sec->off, ext_sec->len);
+		return -EINVAL;
+	}
+
+	/* At least a record size */
+	if (info_left < sizeof(__u32)) {
+		pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
+		return -EINVAL;
+	}
+
+	/* The record size needs to meet the minimum standard */
+	record_size = *(__u32 *)info;
+	if (record_size < ext_sec->min_rec_size ||
+	    record_size & 0x03) {
+		pr_debug("%s section in .BTF.ext has invalid record size %u\n",
+			 ext_sec->desc, record_size);
+		return -EINVAL;
+	}
+
+	sinfo = info + sizeof(__u32);
+	info_left -= sizeof(__u32);
+
+	/* If no records, return failure now so .BTF.ext won't be used. */
+	if (!info_left) {
+		pr_debug("%s section in .BTF.ext has no records", ext_sec->desc);
+		return -EINVAL;
+	}
+
+	while (info_left) {
+		unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
+		__u64 total_record_size;
+		__u32 num_records;
+
+		if (info_left < sec_hdrlen) {
+			pr_debug("%s section header is not found in .BTF.ext\n",
+			     ext_sec->desc);
+			return -EINVAL;
+		}
+
+		num_records = sinfo->num_info;
+		if (num_records == 0) {
+			pr_debug("%s section has incorrect num_records in .BTF.ext\n",
+			     ext_sec->desc);
+			return -EINVAL;
+		}
+
+		total_record_size = sec_hdrlen + (__u64)num_records * record_size;
+		if (info_left < total_record_size) {
+			pr_debug("%s section has incorrect num_records in .BTF.ext\n",
+			     ext_sec->desc);
+			return -EINVAL;
+		}
+
+		info_left -= total_record_size;
+		sinfo = (void *)sinfo + total_record_size;
+		sec_cnt++;
+	}
+
+	ext_info = ext_sec->ext_info;
+	ext_info->len = ext_sec->len - sizeof(__u32);
+	ext_info->rec_size = record_size;
+	ext_info->info = info + sizeof(__u32);
+	ext_info->sec_cnt = sec_cnt;
+
+	return 0;
+}
+
+static int btf_ext_setup_func_info(struct btf_ext *btf_ext)
+{
+	struct btf_ext_sec_setup_param param = {
+		.off = btf_ext->hdr->func_info_off,
+		.len = btf_ext->hdr->func_info_len,
+		.min_rec_size = sizeof(struct bpf_func_info_min),
+		.ext_info = &btf_ext->func_info,
+		.desc = "func_info"
+	};
+
+	return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
+{
+	struct btf_ext_sec_setup_param param = {
+		.off = btf_ext->hdr->line_info_off,
+		.len = btf_ext->hdr->line_info_len,
+		.min_rec_size = sizeof(struct bpf_line_info_min),
+		.ext_info = &btf_ext->line_info,
+		.desc = "line_info",
+	};
+
+	return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_setup_core_relos(struct btf_ext *btf_ext)
+{
+	struct btf_ext_sec_setup_param param = {
+		.off = btf_ext->hdr->core_relo_off,
+		.len = btf_ext->hdr->core_relo_len,
+		.min_rec_size = sizeof(struct bpf_core_relo),
+		.ext_info = &btf_ext->core_relo_info,
+		.desc = "core_relo",
+	};
+
+	return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
+{
+	const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
+
+	if (data_size < offsetofend(struct btf_ext_header, hdr_len) ||
+	    data_size < hdr->hdr_len) {
+		pr_debug("BTF.ext header not found");
+		return -EINVAL;
+	}
+
+	if (hdr->magic == bswap_16(BTF_MAGIC)) {
+		pr_warn("BTF.ext in non-native endianness is not supported\n");
+		return -ENOTSUP;
+	} else if (hdr->magic != BTF_MAGIC) {
+		pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic);
+		return -EINVAL;
+	}
+
+	if (hdr->version != BTF_VERSION) {
+		pr_debug("Unsupported BTF.ext version:%u\n", hdr->version);
+		return -ENOTSUP;
+	}
+
+	if (hdr->flags) {
+		pr_debug("Unsupported BTF.ext flags:%x\n", hdr->flags);
+		return -ENOTSUP;
+	}
+
+	if (data_size == hdr->hdr_len) {
+		pr_debug("BTF.ext has no data\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+void btf_ext__free(struct btf_ext *btf_ext)
+{
+	if (IS_ERR_OR_NULL(btf_ext))
+		return;
+	free(btf_ext->func_info.sec_idxs);
+	free(btf_ext->line_info.sec_idxs);
+	free(btf_ext->core_relo_info.sec_idxs);
+	free(btf_ext->data);
+	free(btf_ext);
+}
+
+struct btf_ext *btf_ext__new(const __u8 *data, __u32 size)
+{
+	struct btf_ext *btf_ext;
+	int err;
+
+	btf_ext = calloc(1, sizeof(struct btf_ext));
+	if (!btf_ext)
+		return libbpf_err_ptr(-ENOMEM);
+
+	btf_ext->data_size = size;
+	btf_ext->data = malloc(size);
+	if (!btf_ext->data) {
+		err = -ENOMEM;
+		goto done;
+	}
+	memcpy(btf_ext->data, data, size);
+
+	err = btf_ext_parse_hdr(btf_ext->data, size);
+	if (err)
+		goto done;
+
+	if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, line_info_len)) {
+		err = -EINVAL;
+		goto done;
+	}
+
+	err = btf_ext_setup_func_info(btf_ext);
+	if (err)
+		goto done;
+
+	err = btf_ext_setup_line_info(btf_ext);
+	if (err)
+		goto done;
+
+	if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len))
+		goto done; /* skip core relos parsing */
+
+	err = btf_ext_setup_core_relos(btf_ext);
+	if (err)
+		goto done;
+
+done:
+	if (err) {
+		btf_ext__free(btf_ext);
+		return libbpf_err_ptr(err);
+	}
+
+	return btf_ext;
+}
+
+const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size)
+{
+	*size = btf_ext->data_size;
+	return btf_ext->data;
+}
+
+struct btf_dedup;
+
+static struct btf_dedup *btf_dedup_new(struct btf *btf, const struct btf_dedup_opts *opts);
+static void btf_dedup_free(struct btf_dedup *d);
+static int btf_dedup_prep(struct btf_dedup *d);
+static int btf_dedup_strings(struct btf_dedup *d);
+static int btf_dedup_prim_types(struct btf_dedup *d);
+static int btf_dedup_struct_types(struct btf_dedup *d);
+static int btf_dedup_ref_types(struct btf_dedup *d);
+static int btf_dedup_resolve_fwds(struct btf_dedup *d);
+static int btf_dedup_compact_types(struct btf_dedup *d);
+static int btf_dedup_remap_types(struct btf_dedup *d);
+
+/*
+ * Deduplicate BTF types and strings.
+ *
+ * BTF dedup algorithm takes as an input `struct btf` representing `.BTF` ELF
+ * section with all BTF type descriptors and string data. It overwrites that
+ * memory in-place with deduplicated types and strings without any loss of
+ * information. If optional `struct btf_ext` representing '.BTF.ext' ELF section
+ * is provided, all the strings referenced from .BTF.ext section are honored
+ * and updated to point to the right offsets after deduplication.
+ *
+ * If function returns with error, type/string data might be garbled and should
+ * be discarded.
+ *
+ * More verbose and detailed description of both problem btf_dedup is solving,
+ * as well as solution could be found at:
+ * https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
+ *
+ * Problem description and justification
+ * =====================================
+ *
+ * BTF type information is typically emitted either as a result of conversion
+ * from DWARF to BTF or directly by compiler. In both cases, each compilation
+ * unit contains information about a subset of all the types that are used
+ * in an application. These subsets are frequently overlapping and contain a lot
+ * of duplicated information when later concatenated together into a single
+ * binary. This algorithm ensures that each unique type is represented by single
+ * BTF type descriptor, greatly reducing resulting size of BTF data.
+ *
+ * Compilation unit isolation and subsequent duplication of data is not the only
+ * problem. The same type hierarchy (e.g., struct and all the type that struct
+ * references) in different compilation units can be represented in BTF to
+ * various degrees of completeness (or, rather, incompleteness) due to
+ * struct/union forward declarations.
+ *
+ * Let's take a look at an example, that we'll use to better understand the
+ * problem (and solution). Suppose we have two compilation units, each using
+ * same `struct S`, but each of them having incomplete type information about
+ * struct's fields:
+ *
+ * // CU #1:
+ * struct S;
+ * struct A {
+ *	int a;
+ *	struct A* self;
+ *	struct S* parent;
+ * };
+ * struct B;
+ * struct S {
+ *	struct A* a_ptr;
+ *	struct B* b_ptr;
+ * };
+ *
+ * // CU #2:
+ * struct S;
+ * struct A;
+ * struct B {
+ *	int b;
+ *	struct B* self;
+ *	struct S* parent;
+ * };
+ * struct S {
+ *	struct A* a_ptr;
+ *	struct B* b_ptr;
+ * };
+ *
+ * In case of CU #1, BTF data will know only that `struct B` exist (but no
+ * more), but will know the complete type information about `struct A`. While
+ * for CU #2, it will know full type information about `struct B`, but will
+ * only know about forward declaration of `struct A` (in BTF terms, it will
+ * have `BTF_KIND_FWD` type descriptor with name `B`).
+ *
+ * This compilation unit isolation means that it's possible that there is no
+ * single CU with complete type information describing structs `S`, `A`, and
+ * `B`. Also, we might get tons of duplicated and redundant type information.
+ *
+ * Additional complication we need to keep in mind comes from the fact that
+ * types, in general, can form graphs containing cycles, not just DAGs.
+ *
+ * While algorithm does deduplication, it also merges and resolves type
+ * information (unless disabled throught `struct btf_opts`), whenever possible.
+ * E.g., in the example above with two compilation units having partial type
+ * information for structs `A` and `B`, the output of algorithm will emit
+ * a single copy of each BTF type that describes structs `A`, `B`, and `S`
+ * (as well as type information for `int` and pointers), as if they were defined
+ * in a single compilation unit as:
+ *
+ * struct A {
+ *	int a;
+ *	struct A* self;
+ *	struct S* parent;
+ * };
+ * struct B {
+ *	int b;
+ *	struct B* self;
+ *	struct S* parent;
+ * };
+ * struct S {
+ *	struct A* a_ptr;
+ *	struct B* b_ptr;
+ * };
+ *
+ * Algorithm summary
+ * =================
+ *
+ * Algorithm completes its work in 7 separate passes:
+ *
+ * 1. Strings deduplication.
+ * 2. Primitive types deduplication (int, enum, fwd).
+ * 3. Struct/union types deduplication.
+ * 4. Resolve unambiguous forward declarations.
+ * 5. Reference types deduplication (pointers, typedefs, arrays, funcs, func
+ *    protos, and const/volatile/restrict modifiers).
+ * 6. Types compaction.
+ * 7. Types remapping.
+ *
+ * Algorithm determines canonical type descriptor, which is a single
+ * representative type for each truly unique type. This canonical type is the
+ * one that will go into final deduplicated BTF type information. For
+ * struct/unions, it is also the type that algorithm will merge additional type
+ * information into (while resolving FWDs), as it discovers it from data in
+ * other CUs. Each input BTF type eventually gets either mapped to itself, if
+ * that type is canonical, or to some other type, if that type is equivalent
+ * and was chosen as canonical representative. This mapping is stored in
+ * `btf_dedup->map` array. This map is also used to record STRUCT/UNION that
+ * FWD type got resolved to.
+ *
+ * To facilitate fast discovery of canonical types, we also maintain canonical
+ * index (`btf_dedup->dedup_table`), which maps type descriptor's signature hash
+ * (i.e., hashed kind, name, size, fields, etc) into a list of canonical types
+ * that match that signature. With sufficiently good choice of type signature
+ * hashing function, we can limit number of canonical types for each unique type
+ * signature to a very small number, allowing to find canonical type for any
+ * duplicated type very quickly.
+ *
+ * Struct/union deduplication is the most critical part and algorithm for
+ * deduplicating structs/unions is described in greater details in comments for
+ * `btf_dedup_is_equiv` function.
+ */
+int btf__dedup(struct btf *btf, const struct btf_dedup_opts *opts)
+{
+	struct btf_dedup *d;
+	int err;
+
+	if (!OPTS_VALID(opts, btf_dedup_opts))
+		return libbpf_err(-EINVAL);
+
+	d = btf_dedup_new(btf, opts);
+	if (IS_ERR(d)) {
+		pr_debug("btf_dedup_new failed: %ld", PTR_ERR(d));
+		return libbpf_err(-EINVAL);
+	}
+
+	if (btf_ensure_modifiable(btf)) {
+		err = -ENOMEM;
+		goto done;
+	}
+
+	err = btf_dedup_prep(d);
+	if (err) {
+		pr_debug("btf_dedup_prep failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_strings(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_strings failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_prim_types(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_prim_types failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_struct_types(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_struct_types failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_resolve_fwds(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_resolve_fwds failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_ref_types(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_ref_types failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_compact_types(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_compact_types failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_remap_types(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_remap_types failed:%d\n", err);
+		goto done;
+	}
+
+done:
+	btf_dedup_free(d);
+	return libbpf_err(err);
+}
+
+#define BTF_UNPROCESSED_ID ((__u32)-1)
+#define BTF_IN_PROGRESS_ID ((__u32)-2)
+
+struct btf_dedup {
+	/* .BTF section to be deduped in-place */
+	struct btf *btf;
+	/*
+	 * Optional .BTF.ext section. When provided, any strings referenced
+	 * from it will be taken into account when deduping strings
+	 */
+	struct btf_ext *btf_ext;
+	/*
+	 * This is a map from any type's signature hash to a list of possible
+	 * canonical representative type candidates. Hash collisions are
+	 * ignored, so even types of various kinds can share same list of
+	 * candidates, which is fine because we rely on subsequent
+	 * btf_xxx_equal() checks to authoritatively verify type equality.
+	 */
+	struct hashmap *dedup_table;
+	/* Canonical types map */
+	__u32 *map;
+	/* Hypothetical mapping, used during type graph equivalence checks */
+	__u32 *hypot_map;
+	__u32 *hypot_list;
+	size_t hypot_cnt;
+	size_t hypot_cap;
+	/* Whether hypothetical mapping, if successful, would need to adjust
+	 * already canonicalized types (due to a new forward declaration to
+	 * concrete type resolution). In such case, during split BTF dedup
+	 * candidate type would still be considered as different, because base
+	 * BTF is considered to be immutable.
+	 */
+	bool hypot_adjust_canon;
+	/* Various option modifying behavior of algorithm */
+	struct btf_dedup_opts opts;
+	/* temporary strings deduplication state */
+	struct strset *strs_set;
+};
+
+static long hash_combine(long h, long value)
+{
+	return h * 31 + value;
+}
+
+#define for_each_dedup_cand(d, node, hash) \
+	hashmap__for_each_key_entry(d->dedup_table, node, hash)
+
+static int btf_dedup_table_add(struct btf_dedup *d, long hash, __u32 type_id)
+{
+	return hashmap__append(d->dedup_table, hash, type_id);
+}
+
+static int btf_dedup_hypot_map_add(struct btf_dedup *d,
+				   __u32 from_id, __u32 to_id)
+{
+	if (d->hypot_cnt == d->hypot_cap) {
+		__u32 *new_list;
+
+		d->hypot_cap += max((size_t)16, d->hypot_cap / 2);
+		new_list = libbpf_reallocarray(d->hypot_list, d->hypot_cap, sizeof(__u32));
+		if (!new_list)
+			return -ENOMEM;
+		d->hypot_list = new_list;
+	}
+	d->hypot_list[d->hypot_cnt++] = from_id;
+	d->hypot_map[from_id] = to_id;
+	return 0;
+}
+
+static void btf_dedup_clear_hypot_map(struct btf_dedup *d)
+{
+	int i;
+
+	for (i = 0; i < d->hypot_cnt; i++)
+		d->hypot_map[d->hypot_list[i]] = BTF_UNPROCESSED_ID;
+	d->hypot_cnt = 0;
+	d->hypot_adjust_canon = false;
+}
+
+static void btf_dedup_free(struct btf_dedup *d)
+{
+	hashmap__free(d->dedup_table);
+	d->dedup_table = NULL;
+
+	free(d->map);
+	d->map = NULL;
+
+	free(d->hypot_map);
+	d->hypot_map = NULL;
+
+	free(d->hypot_list);
+	d->hypot_list = NULL;
+
+	free(d);
+}
+
+static size_t btf_dedup_identity_hash_fn(long key, void *ctx)
+{
+	return key;
+}
+
+static size_t btf_dedup_collision_hash_fn(long key, void *ctx)
+{
+	return 0;
+}
+
+static bool btf_dedup_equal_fn(long k1, long k2, void *ctx)
+{
+	return k1 == k2;
+}
+
+static struct btf_dedup *btf_dedup_new(struct btf *btf, const struct btf_dedup_opts *opts)
+{
+	struct btf_dedup *d = calloc(1, sizeof(struct btf_dedup));
+	hashmap_hash_fn hash_fn = btf_dedup_identity_hash_fn;
+	int i, err = 0, type_cnt;
+
+	if (!d)
+		return ERR_PTR(-ENOMEM);
+
+	if (OPTS_GET(opts, force_collisions, false))
+		hash_fn = btf_dedup_collision_hash_fn;
+
+	d->btf = btf;
+	d->btf_ext = OPTS_GET(opts, btf_ext, NULL);
+
+	d->dedup_table = hashmap__new(hash_fn, btf_dedup_equal_fn, NULL);
+	if (IS_ERR(d->dedup_table)) {
+		err = PTR_ERR(d->dedup_table);
+		d->dedup_table = NULL;
+		goto done;
+	}
+
+	type_cnt = btf__type_cnt(btf);
+	d->map = malloc(sizeof(__u32) * type_cnt);
+	if (!d->map) {
+		err = -ENOMEM;
+		goto done;
+	}
+	/* special BTF "void" type is made canonical immediately */
+	d->map[0] = 0;
+	for (i = 1; i < type_cnt; i++) {
+		struct btf_type *t = btf_type_by_id(d->btf, i);
+
+		/* VAR and DATASEC are never deduped and are self-canonical */
+		if (btf_is_var(t) || btf_is_datasec(t))
+			d->map[i] = i;
+		else
+			d->map[i] = BTF_UNPROCESSED_ID;
+	}
+
+	d->hypot_map = malloc(sizeof(__u32) * type_cnt);
+	if (!d->hypot_map) {
+		err = -ENOMEM;
+		goto done;
+	}
+	for (i = 0; i < type_cnt; i++)
+		d->hypot_map[i] = BTF_UNPROCESSED_ID;
+
+done:
+	if (err) {
+		btf_dedup_free(d);
+		return ERR_PTR(err);
+	}
+
+	return d;
+}
+
+/*
+ * Iterate over all possible places in .BTF and .BTF.ext that can reference
+ * string and pass pointer to it to a provided callback `fn`.
+ */
+static int btf_for_each_str_off(struct btf_dedup *d, str_off_visit_fn fn, void *ctx)
+{
+	int i, r;
+
+	for (i = 0; i < d->btf->nr_types; i++) {
+		struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
+
+		r = btf_type_visit_str_offs(t, fn, ctx);
+		if (r)
+			return r;
+	}
+
+	if (!d->btf_ext)
+		return 0;
+
+	r = btf_ext_visit_str_offs(d->btf_ext, fn, ctx);
+	if (r)
+		return r;
+
+	return 0;
+}
+
+static int strs_dedup_remap_str_off(__u32 *str_off_ptr, void *ctx)
+{
+	struct btf_dedup *d = ctx;
+	__u32 str_off = *str_off_ptr;
+	const char *s;
+	int off, err;
+
+	/* don't touch empty string or string in main BTF */
+	if (str_off == 0 || str_off < d->btf->start_str_off)
+		return 0;
+
+	s = btf__str_by_offset(d->btf, str_off);
+	if (d->btf->base_btf) {
+		err = btf__find_str(d->btf->base_btf, s);
+		if (err >= 0) {
+			*str_off_ptr = err;
+			return 0;
+		}
+		if (err != -ENOENT)
+			return err;
+	}
+
+	off = strset__add_str(d->strs_set, s);
+	if (off < 0)
+		return off;
+
+	*str_off_ptr = d->btf->start_str_off + off;
+	return 0;
+}
+
+/*
+ * Dedup string and filter out those that are not referenced from either .BTF
+ * or .BTF.ext (if provided) sections.
+ *
+ * This is done by building index of all strings in BTF's string section,
+ * then iterating over all entities that can reference strings (e.g., type
+ * names, struct field names, .BTF.ext line info, etc) and marking corresponding
+ * strings as used. After that all used strings are deduped and compacted into
+ * sequential blob of memory and new offsets are calculated. Then all the string
+ * references are iterated again and rewritten using new offsets.
+ */
+static int btf_dedup_strings(struct btf_dedup *d)
+{
+	int err;
+
+	if (d->btf->strs_deduped)
+		return 0;
+
+	d->strs_set = strset__new(BTF_MAX_STR_OFFSET, NULL, 0);
+	if (IS_ERR(d->strs_set)) {
+		err = PTR_ERR(d->strs_set);
+		goto err_out;
+	}
+
+	if (!d->btf->base_btf) {
+		/* insert empty string; we won't be looking it up during strings
+		 * dedup, but it's good to have it for generic BTF string lookups
+		 */
+		err = strset__add_str(d->strs_set, "");
+		if (err < 0)
+			goto err_out;
+	}
+
+	/* remap string offsets */
+	err = btf_for_each_str_off(d, strs_dedup_remap_str_off, d);
+	if (err)
+		goto err_out;
+
+	/* replace BTF string data and hash with deduped ones */
+	strset__free(d->btf->strs_set);
+	d->btf->hdr->str_len = strset__data_size(d->strs_set);
+	d->btf->strs_set = d->strs_set;
+	d->strs_set = NULL;
+	d->btf->strs_deduped = true;
+	return 0;
+
+err_out:
+	strset__free(d->strs_set);
+	d->strs_set = NULL;
+
+	return err;
+}
+
+static long btf_hash_common(struct btf_type *t)
+{
+	long h;
+
+	h = hash_combine(0, t->name_off);
+	h = hash_combine(h, t->info);
+	h = hash_combine(h, t->size);
+	return h;
+}
+
+static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
+{
+	return t1->name_off == t2->name_off &&
+	       t1->info == t2->info &&
+	       t1->size == t2->size;
+}
+
+/* Calculate type signature hash of INT or TAG. */
+static long btf_hash_int_decl_tag(struct btf_type *t)
+{
+	__u32 info = *(__u32 *)(t + 1);
+	long h;
+
+	h = btf_hash_common(t);
+	h = hash_combine(h, info);
+	return h;
+}
+
+/* Check structural equality of two INTs or TAGs. */
+static bool btf_equal_int_tag(struct btf_type *t1, struct btf_type *t2)
+{
+	__u32 info1, info2;
+
+	if (!btf_equal_common(t1, t2))
+		return false;
+	info1 = *(__u32 *)(t1 + 1);
+	info2 = *(__u32 *)(t2 + 1);
+	return info1 == info2;
+}
+
+/* Calculate type signature hash of ENUM/ENUM64. */
+static long btf_hash_enum(struct btf_type *t)
+{
+	long h;
+
+	/* don't hash vlen, enum members and size to support enum fwd resolving */
+	h = hash_combine(0, t->name_off);
+	return h;
+}
+
+static bool btf_equal_enum_members(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_enum *m1, *m2;
+	__u16 vlen;
+	int i;
+
+	vlen = btf_vlen(t1);
+	m1 = btf_enum(t1);
+	m2 = btf_enum(t2);
+	for (i = 0; i < vlen; i++) {
+		if (m1->name_off != m2->name_off || m1->val != m2->val)
+			return false;
+		m1++;
+		m2++;
+	}
+	return true;
+}
+
+static bool btf_equal_enum64_members(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_enum64 *m1, *m2;
+	__u16 vlen;
+	int i;
+
+	vlen = btf_vlen(t1);
+	m1 = btf_enum64(t1);
+	m2 = btf_enum64(t2);
+	for (i = 0; i < vlen; i++) {
+		if (m1->name_off != m2->name_off || m1->val_lo32 != m2->val_lo32 ||
+		    m1->val_hi32 != m2->val_hi32)
+			return false;
+		m1++;
+		m2++;
+	}
+	return true;
+}
+
+/* Check structural equality of two ENUMs or ENUM64s. */
+static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
+{
+	if (!btf_equal_common(t1, t2))
+		return false;
+
+	/* t1 & t2 kinds are identical because of btf_equal_common */
+	if (btf_kind(t1) == BTF_KIND_ENUM)
+		return btf_equal_enum_members(t1, t2);
+	else
+		return btf_equal_enum64_members(t1, t2);
+}
+
+static inline bool btf_is_enum_fwd(struct btf_type *t)
+{
+	return btf_is_any_enum(t) && btf_vlen(t) == 0;
+}
+
+static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
+{
+	if (!btf_is_enum_fwd(t1) && !btf_is_enum_fwd(t2))
+		return btf_equal_enum(t1, t2);
+	/* At this point either t1 or t2 or both are forward declarations, thus:
+	 * - skip comparing vlen because it is zero for forward declarations;
+	 * - skip comparing size to allow enum forward declarations
+	 *   to be compatible with enum64 full declarations;
+	 * - skip comparing kind for the same reason.
+	 */
+	return t1->name_off == t2->name_off &&
+	       btf_is_any_enum(t1) && btf_is_any_enum(t2);
+}
+
+/*
+ * Calculate type signature hash of STRUCT/UNION, ignoring referenced type IDs,
+ * as referenced type IDs equivalence is established separately during type
+ * graph equivalence check algorithm.
+ */
+static long btf_hash_struct(struct btf_type *t)
+{
+	const struct btf_member *member = btf_members(t);
+	__u32 vlen = btf_vlen(t);
+	long h = btf_hash_common(t);
+	int i;
+
+	for (i = 0; i < vlen; i++) {
+		h = hash_combine(h, member->name_off);
+		h = hash_combine(h, member->offset);
+		/* no hashing of referenced type ID, it can be unresolved yet */
+		member++;
+	}
+	return h;
+}
+
+/*
+ * Check structural compatibility of two STRUCTs/UNIONs, ignoring referenced
+ * type IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_member *m1, *m2;
+	__u16 vlen;
+	int i;
+
+	if (!btf_equal_common(t1, t2))
+		return false;
+
+	vlen = btf_vlen(t1);
+	m1 = btf_members(t1);
+	m2 = btf_members(t2);
+	for (i = 0; i < vlen; i++) {
+		if (m1->name_off != m2->name_off || m1->offset != m2->offset)
+			return false;
+		m1++;
+		m2++;
+	}
+	return true;
+}
+
+/*
+ * Calculate type signature hash of ARRAY, including referenced type IDs,
+ * under assumption that they were already resolved to canonical type IDs and
+ * are not going to change.
+ */
+static long btf_hash_array(struct btf_type *t)
+{
+	const struct btf_array *info = btf_array(t);
+	long h = btf_hash_common(t);
+
+	h = hash_combine(h, info->type);
+	h = hash_combine(h, info->index_type);
+	h = hash_combine(h, info->nelems);
+	return h;
+}
+
+/*
+ * Check exact equality of two ARRAYs, taking into account referenced
+ * type IDs, under assumption that they were already resolved to canonical
+ * type IDs and are not going to change.
+ * This function is called during reference types deduplication to compare
+ * ARRAY to potential canonical representative.
+ */
+static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_array *info1, *info2;
+
+	if (!btf_equal_common(t1, t2))
+		return false;
+
+	info1 = btf_array(t1);
+	info2 = btf_array(t2);
+	return info1->type == info2->type &&
+	       info1->index_type == info2->index_type &&
+	       info1->nelems == info2->nelems;
+}
+
+/*
+ * Check structural compatibility of two ARRAYs, ignoring referenced type
+ * IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
+{
+	if (!btf_equal_common(t1, t2))
+		return false;
+
+	return btf_array(t1)->nelems == btf_array(t2)->nelems;
+}
+
+/*
+ * Calculate type signature hash of FUNC_PROTO, including referenced type IDs,
+ * under assumption that they were already resolved to canonical type IDs and
+ * are not going to change.
+ */
+static long btf_hash_fnproto(struct btf_type *t)
+{
+	const struct btf_param *member = btf_params(t);
+	__u16 vlen = btf_vlen(t);
+	long h = btf_hash_common(t);
+	int i;
+
+	for (i = 0; i < vlen; i++) {
+		h = hash_combine(h, member->name_off);
+		h = hash_combine(h, member->type);
+		member++;
+	}
+	return h;
+}
+
+/*
+ * Check exact equality of two FUNC_PROTOs, taking into account referenced
+ * type IDs, under assumption that they were already resolved to canonical
+ * type IDs and are not going to change.
+ * This function is called during reference types deduplication to compare
+ * FUNC_PROTO to potential canonical representative.
+ */
+static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_param *m1, *m2;
+	__u16 vlen;
+	int i;
+
+	if (!btf_equal_common(t1, t2))
+		return false;
+
+	vlen = btf_vlen(t1);
+	m1 = btf_params(t1);
+	m2 = btf_params(t2);
+	for (i = 0; i < vlen; i++) {
+		if (m1->name_off != m2->name_off || m1->type != m2->type)
+			return false;
+		m1++;
+		m2++;
+	}
+	return true;
+}
+
+/*
+ * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
+ * IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_param *m1, *m2;
+	__u16 vlen;
+	int i;
+
+	/* skip return type ID */
+	if (t1->name_off != t2->name_off || t1->info != t2->info)
+		return false;
+
+	vlen = btf_vlen(t1);
+	m1 = btf_params(t1);
+	m2 = btf_params(t2);
+	for (i = 0; i < vlen; i++) {
+		if (m1->name_off != m2->name_off)
+			return false;
+		m1++;
+		m2++;
+	}
+	return true;
+}
+
+/* Prepare split BTF for deduplication by calculating hashes of base BTF's
+ * types and initializing the rest of the state (canonical type mapping) for
+ * the fixed base BTF part.
+ */
+static int btf_dedup_prep(struct btf_dedup *d)
+{
+	struct btf_type *t;
+	int type_id;
+	long h;
+
+	if (!d->btf->base_btf)
+		return 0;
+
+	for (type_id = 1; type_id < d->btf->start_id; type_id++) {
+		t = btf_type_by_id(d->btf, type_id);
+
+		/* all base BTF types are self-canonical by definition */
+		d->map[type_id] = type_id;
+
+		switch (btf_kind(t)) {
+		case BTF_KIND_VAR:
+		case BTF_KIND_DATASEC:
+			/* VAR and DATASEC are never hash/deduplicated */
+			continue;
+		case BTF_KIND_CONST:
+		case BTF_KIND_VOLATILE:
+		case BTF_KIND_RESTRICT:
+		case BTF_KIND_PTR:
+		case BTF_KIND_FWD:
+		case BTF_KIND_TYPEDEF:
+		case BTF_KIND_FUNC:
+		case BTF_KIND_FLOAT:
+		case BTF_KIND_TYPE_TAG:
+			h = btf_hash_common(t);
+			break;
+		case BTF_KIND_INT:
+		case BTF_KIND_DECL_TAG:
+			h = btf_hash_int_decl_tag(t);
+			break;
+		case BTF_KIND_ENUM:
+		case BTF_KIND_ENUM64:
+			h = btf_hash_enum(t);
+			break;
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION:
+			h = btf_hash_struct(t);
+			break;
+		case BTF_KIND_ARRAY:
+			h = btf_hash_array(t);
+			break;
+		case BTF_KIND_FUNC_PROTO:
+			h = btf_hash_fnproto(t);
+			break;
+		default:
+			pr_debug("unknown kind %d for type [%d]\n", btf_kind(t), type_id);
+			return -EINVAL;
+		}
+		if (btf_dedup_table_add(d, h, type_id))
+			return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/*
+ * Deduplicate primitive types, that can't reference other types, by calculating
+ * their type signature hash and comparing them with any possible canonical
+ * candidate. If no canonical candidate matches, type itself is marked as
+ * canonical and is added into `btf_dedup->dedup_table` as another candidate.
+ */
+static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
+{
+	struct btf_type *t = btf_type_by_id(d->btf, type_id);
+	struct hashmap_entry *hash_entry;
+	struct btf_type *cand;
+	/* if we don't find equivalent type, then we are canonical */
+	__u32 new_id = type_id;
+	__u32 cand_id;
+	long h;
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_CONST:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_ARRAY:
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+	case BTF_KIND_FUNC:
+	case BTF_KIND_FUNC_PROTO:
+	case BTF_KIND_VAR:
+	case BTF_KIND_DATASEC:
+	case BTF_KIND_DECL_TAG:
+	case BTF_KIND_TYPE_TAG:
+		return 0;
+
+	case BTF_KIND_INT:
+		h = btf_hash_int_decl_tag(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = hash_entry->value;
+			cand = btf_type_by_id(d->btf, cand_id);
+			if (btf_equal_int_tag(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		h = btf_hash_enum(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = hash_entry->value;
+			cand = btf_type_by_id(d->btf, cand_id);
+			if (btf_equal_enum(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+			if (btf_compat_enum(t, cand)) {
+				if (btf_is_enum_fwd(t)) {
+					/* resolve fwd to full enum */
+					new_id = cand_id;
+					break;
+				}
+				/* resolve canonical enum fwd to full enum */
+				d->map[cand_id] = type_id;
+			}
+		}
+		break;
+
+	case BTF_KIND_FWD:
+	case BTF_KIND_FLOAT:
+		h = btf_hash_common(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = hash_entry->value;
+			cand = btf_type_by_id(d->btf, cand_id);
+			if (btf_equal_common(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	d->map[type_id] = new_id;
+	if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int btf_dedup_prim_types(struct btf_dedup *d)
+{
+	int i, err;
+
+	for (i = 0; i < d->btf->nr_types; i++) {
+		err = btf_dedup_prim_type(d, d->btf->start_id + i);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+/*
+ * Check whether type is already mapped into canonical one (could be to itself).
+ */
+static inline bool is_type_mapped(struct btf_dedup *d, uint32_t type_id)
+{
+	return d->map[type_id] <= BTF_MAX_NR_TYPES;
+}
+
+/*
+ * Resolve type ID into its canonical type ID, if any; otherwise return original
+ * type ID. If type is FWD and is resolved into STRUCT/UNION already, follow
+ * STRUCT/UNION link and resolve it into canonical type ID as well.
+ */
+static inline __u32 resolve_type_id(struct btf_dedup *d, __u32 type_id)
+{
+	while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
+		type_id = d->map[type_id];
+	return type_id;
+}
+
+/*
+ * Resolve FWD to underlying STRUCT/UNION, if any; otherwise return original
+ * type ID.
+ */
+static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
+{
+	__u32 orig_type_id = type_id;
+
+	if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
+		return type_id;
+
+	while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
+		type_id = d->map[type_id];
+
+	if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
+		return type_id;
+
+	return orig_type_id;
+}
+
+
+static inline __u16 btf_fwd_kind(struct btf_type *t)
+{
+	return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
+}
+
+/* Check if given two types are identical ARRAY definitions */
+static bool btf_dedup_identical_arrays(struct btf_dedup *d, __u32 id1, __u32 id2)
+{
+	struct btf_type *t1, *t2;
+
+	t1 = btf_type_by_id(d->btf, id1);
+	t2 = btf_type_by_id(d->btf, id2);
+	if (!btf_is_array(t1) || !btf_is_array(t2))
+		return false;
+
+	return btf_equal_array(t1, t2);
+}
+
+/* Check if given two types are identical STRUCT/UNION definitions */
+static bool btf_dedup_identical_structs(struct btf_dedup *d, __u32 id1, __u32 id2)
+{
+	const struct btf_member *m1, *m2;
+	struct btf_type *t1, *t2;
+	int n, i;
+
+	t1 = btf_type_by_id(d->btf, id1);
+	t2 = btf_type_by_id(d->btf, id2);
+
+	if (!btf_is_composite(t1) || btf_kind(t1) != btf_kind(t2))
+		return false;
+
+	if (!btf_shallow_equal_struct(t1, t2))
+		return false;
+
+	m1 = btf_members(t1);
+	m2 = btf_members(t2);
+	for (i = 0, n = btf_vlen(t1); i < n; i++, m1++, m2++) {
+		if (m1->type != m2->type &&
+		    !btf_dedup_identical_arrays(d, m1->type, m2->type) &&
+		    !btf_dedup_identical_structs(d, m1->type, m2->type))
+			return false;
+	}
+	return true;
+}
+
+/*
+ * Check equivalence of BTF type graph formed by candidate struct/union (we'll
+ * call it "candidate graph" in this description for brevity) to a type graph
+ * formed by (potential) canonical struct/union ("canonical graph" for brevity
+ * here, though keep in mind that not all types in canonical graph are
+ * necessarily canonical representatives themselves, some of them might be
+ * duplicates or its uniqueness might not have been established yet).
+ * Returns:
+ *  - >0, if type graphs are equivalent;
+ *  -  0, if not equivalent;
+ *  - <0, on error.
+ *
+ * Algorithm performs side-by-side DFS traversal of both type graphs and checks
+ * equivalence of BTF types at each step. If at any point BTF types in candidate
+ * and canonical graphs are not compatible structurally, whole graphs are
+ * incompatible. If types are structurally equivalent (i.e., all information
+ * except referenced type IDs is exactly the same), a mapping from `canon_id` to
+ * a `cand_id` is recored in hypothetical mapping (`btf_dedup->hypot_map`).
+ * If a type references other types, then those referenced types are checked
+ * for equivalence recursively.
+ *
+ * During DFS traversal, if we find that for current `canon_id` type we
+ * already have some mapping in hypothetical map, we check for two possible
+ * situations:
+ *   - `canon_id` is mapped to exactly the same type as `cand_id`. This will
+ *     happen when type graphs have cycles. In this case we assume those two
+ *     types are equivalent.
+ *   - `canon_id` is mapped to different type. This is contradiction in our
+ *     hypothetical mapping, because same graph in canonical graph corresponds
+ *     to two different types in candidate graph, which for equivalent type
+ *     graphs shouldn't happen. This condition terminates equivalence check
+ *     with negative result.
+ *
+ * If type graphs traversal exhausts types to check and find no contradiction,
+ * then type graphs are equivalent.
+ *
+ * When checking types for equivalence, there is one special case: FWD types.
+ * If FWD type resolution is allowed and one of the types (either from canonical
+ * or candidate graph) is FWD and other is STRUCT/UNION (depending on FWD's kind
+ * flag) and their names match, hypothetical mapping is updated to point from
+ * FWD to STRUCT/UNION. If graphs will be determined as equivalent successfully,
+ * this mapping will be used to record FWD -> STRUCT/UNION mapping permanently.
+ *
+ * Technically, this could lead to incorrect FWD to STRUCT/UNION resolution,
+ * if there are two exactly named (or anonymous) structs/unions that are
+ * compatible structurally, one of which has FWD field, while other is concrete
+ * STRUCT/UNION, but according to C sources they are different structs/unions
+ * that are referencing different types with the same name. This is extremely
+ * unlikely to happen, but btf_dedup API allows to disable FWD resolution if
+ * this logic is causing problems.
+ *
+ * Doing FWD resolution means that both candidate and/or canonical graphs can
+ * consists of portions of the graph that come from multiple compilation units.
+ * This is due to the fact that types within single compilation unit are always
+ * deduplicated and FWDs are already resolved, if referenced struct/union
+ * definiton is available. So, if we had unresolved FWD and found corresponding
+ * STRUCT/UNION, they will be from different compilation units. This
+ * consequently means that when we "link" FWD to corresponding STRUCT/UNION,
+ * type graph will likely have at least two different BTF types that describe
+ * same type (e.g., most probably there will be two different BTF types for the
+ * same 'int' primitive type) and could even have "overlapping" parts of type
+ * graph that describe same subset of types.
+ *
+ * This in turn means that our assumption that each type in canonical graph
+ * must correspond to exactly one type in candidate graph might not hold
+ * anymore and will make it harder to detect contradictions using hypothetical
+ * map. To handle this problem, we allow to follow FWD -> STRUCT/UNION
+ * resolution only in canonical graph. FWDs in candidate graphs are never
+ * resolved. To see why it's OK, let's check all possible situations w.r.t. FWDs
+ * that can occur:
+ *   - Both types in canonical and candidate graphs are FWDs. If they are
+ *     structurally equivalent, then they can either be both resolved to the
+ *     same STRUCT/UNION or not resolved at all. In both cases they are
+ *     equivalent and there is no need to resolve FWD on candidate side.
+ *   - Both types in canonical and candidate graphs are concrete STRUCT/UNION,
+ *     so nothing to resolve as well, algorithm will check equivalence anyway.
+ *   - Type in canonical graph is FWD, while type in candidate is concrete
+ *     STRUCT/UNION. In this case candidate graph comes from single compilation
+ *     unit, so there is exactly one BTF type for each unique C type. After
+ *     resolving FWD into STRUCT/UNION, there might be more than one BTF type
+ *     in canonical graph mapping to single BTF type in candidate graph, but
+ *     because hypothetical mapping maps from canonical to candidate types, it's
+ *     alright, and we still maintain the property of having single `canon_id`
+ *     mapping to single `cand_id` (there could be two different `canon_id`
+ *     mapped to the same `cand_id`, but it's not contradictory).
+ *   - Type in canonical graph is concrete STRUCT/UNION, while type in candidate
+ *     graph is FWD. In this case we are just going to check compatibility of
+ *     STRUCT/UNION and corresponding FWD, and if they are compatible, we'll
+ *     assume that whatever STRUCT/UNION FWD resolves to must be equivalent to
+ *     a concrete STRUCT/UNION from canonical graph. If the rest of type graphs
+ *     turn out equivalent, we'll re-resolve FWD to concrete STRUCT/UNION from
+ *     canonical graph.
+ */
+static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
+			      __u32 canon_id)
+{
+	struct btf_type *cand_type;
+	struct btf_type *canon_type;
+	__u32 hypot_type_id;
+	__u16 cand_kind;
+	__u16 canon_kind;
+	int i, eq;
+
+	/* if both resolve to the same canonical, they must be equivalent */
+	if (resolve_type_id(d, cand_id) == resolve_type_id(d, canon_id))
+		return 1;
+
+	canon_id = resolve_fwd_id(d, canon_id);
+
+	hypot_type_id = d->hypot_map[canon_id];
+	if (hypot_type_id <= BTF_MAX_NR_TYPES) {
+		if (hypot_type_id == cand_id)
+			return 1;
+		/* In some cases compiler will generate different DWARF types
+		 * for *identical* array type definitions and use them for
+		 * different fields within the *same* struct. This breaks type
+		 * equivalence check, which makes an assumption that candidate
+		 * types sub-graph has a consistent and deduped-by-compiler
+		 * types within a single CU. So work around that by explicitly
+		 * allowing identical array types here.
+		 */
+		if (btf_dedup_identical_arrays(d, hypot_type_id, cand_id))
+			return 1;
+		/* It turns out that similar situation can happen with
+		 * struct/union sometimes, sigh... Handle the case where
+		 * structs/unions are exactly the same, down to the referenced
+		 * type IDs. Anything more complicated (e.g., if referenced
+		 * types are different, but equivalent) is *way more*
+		 * complicated and requires a many-to-many equivalence mapping.
+		 */
+		if (btf_dedup_identical_structs(d, hypot_type_id, cand_id))
+			return 1;
+		return 0;
+	}
+
+	if (btf_dedup_hypot_map_add(d, canon_id, cand_id))
+		return -ENOMEM;
+
+	cand_type = btf_type_by_id(d->btf, cand_id);
+	canon_type = btf_type_by_id(d->btf, canon_id);
+	cand_kind = btf_kind(cand_type);
+	canon_kind = btf_kind(canon_type);
+
+	if (cand_type->name_off != canon_type->name_off)
+		return 0;
+
+	/* FWD <--> STRUCT/UNION equivalence check, if enabled */
+	if ((cand_kind == BTF_KIND_FWD || canon_kind == BTF_KIND_FWD)
+	    && cand_kind != canon_kind) {
+		__u16 real_kind;
+		__u16 fwd_kind;
+
+		if (cand_kind == BTF_KIND_FWD) {
+			real_kind = canon_kind;
+			fwd_kind = btf_fwd_kind(cand_type);
+		} else {
+			real_kind = cand_kind;
+			fwd_kind = btf_fwd_kind(canon_type);
+			/* we'd need to resolve base FWD to STRUCT/UNION */
+			if (fwd_kind == real_kind && canon_id < d->btf->start_id)
+				d->hypot_adjust_canon = true;
+		}
+		return fwd_kind == real_kind;
+	}
+
+	if (cand_kind != canon_kind)
+		return 0;
+
+	switch (cand_kind) {
+	case BTF_KIND_INT:
+		return btf_equal_int_tag(cand_type, canon_type);
+
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		return btf_compat_enum(cand_type, canon_type);
+
+	case BTF_KIND_FWD:
+	case BTF_KIND_FLOAT:
+		return btf_equal_common(cand_type, canon_type);
+
+	case BTF_KIND_CONST:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_FUNC:
+	case BTF_KIND_TYPE_TAG:
+		if (cand_type->info != canon_type->info)
+			return 0;
+		return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
+
+	case BTF_KIND_ARRAY: {
+		const struct btf_array *cand_arr, *canon_arr;
+
+		if (!btf_compat_array(cand_type, canon_type))
+			return 0;
+		cand_arr = btf_array(cand_type);
+		canon_arr = btf_array(canon_type);
+		eq = btf_dedup_is_equiv(d, cand_arr->index_type, canon_arr->index_type);
+		if (eq <= 0)
+			return eq;
+		return btf_dedup_is_equiv(d, cand_arr->type, canon_arr->type);
+	}
+
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		const struct btf_member *cand_m, *canon_m;
+		__u16 vlen;
+
+		if (!btf_shallow_equal_struct(cand_type, canon_type))
+			return 0;
+		vlen = btf_vlen(cand_type);
+		cand_m = btf_members(cand_type);
+		canon_m = btf_members(canon_type);
+		for (i = 0; i < vlen; i++) {
+			eq = btf_dedup_is_equiv(d, cand_m->type, canon_m->type);
+			if (eq <= 0)
+				return eq;
+			cand_m++;
+			canon_m++;
+		}
+
+		return 1;
+	}
+
+	case BTF_KIND_FUNC_PROTO: {
+		const struct btf_param *cand_p, *canon_p;
+		__u16 vlen;
+
+		if (!btf_compat_fnproto(cand_type, canon_type))
+			return 0;
+		eq = btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
+		if (eq <= 0)
+			return eq;
+		vlen = btf_vlen(cand_type);
+		cand_p = btf_params(cand_type);
+		canon_p = btf_params(canon_type);
+		for (i = 0; i < vlen; i++) {
+			eq = btf_dedup_is_equiv(d, cand_p->type, canon_p->type);
+			if (eq <= 0)
+				return eq;
+			cand_p++;
+			canon_p++;
+		}
+		return 1;
+	}
+
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/*
+ * Use hypothetical mapping, produced by successful type graph equivalence
+ * check, to augment existing struct/union canonical mapping, where possible.
+ *
+ * If BTF_KIND_FWD resolution is allowed, this mapping is also used to record
+ * FWD -> STRUCT/UNION correspondence as well. FWD resolution is bidirectional:
+ * it doesn't matter if FWD type was part of canonical graph or candidate one,
+ * we are recording the mapping anyway. As opposed to carefulness required
+ * for struct/union correspondence mapping (described below), for FWD resolution
+ * it's not important, as by the time that FWD type (reference type) will be
+ * deduplicated all structs/unions will be deduped already anyway.
+ *
+ * Recording STRUCT/UNION mapping is purely a performance optimization and is
+ * not required for correctness. It needs to be done carefully to ensure that
+ * struct/union from candidate's type graph is not mapped into corresponding
+ * struct/union from canonical type graph that itself hasn't been resolved into
+ * canonical representative. The only guarantee we have is that canonical
+ * struct/union was determined as canonical and that won't change. But any
+ * types referenced through that struct/union fields could have been not yet
+ * resolved, so in case like that it's too early to establish any kind of
+ * correspondence between structs/unions.
+ *
+ * No canonical correspondence is derived for primitive types (they are already
+ * deduplicated completely already anyway) or reference types (they rely on
+ * stability of struct/union canonical relationship for equivalence checks).
+ */
+static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
+{
+	__u32 canon_type_id, targ_type_id;
+	__u16 t_kind, c_kind;
+	__u32 t_id, c_id;
+	int i;
+
+	for (i = 0; i < d->hypot_cnt; i++) {
+		canon_type_id = d->hypot_list[i];
+		targ_type_id = d->hypot_map[canon_type_id];
+		t_id = resolve_type_id(d, targ_type_id);
+		c_id = resolve_type_id(d, canon_type_id);
+		t_kind = btf_kind(btf__type_by_id(d->btf, t_id));
+		c_kind = btf_kind(btf__type_by_id(d->btf, c_id));
+		/*
+		 * Resolve FWD into STRUCT/UNION.
+		 * It's ok to resolve FWD into STRUCT/UNION that's not yet
+		 * mapped to canonical representative (as opposed to
+		 * STRUCT/UNION <--> STRUCT/UNION mapping logic below), because
+		 * eventually that struct is going to be mapped and all resolved
+		 * FWDs will automatically resolve to correct canonical
+		 * representative. This will happen before ref type deduping,
+		 * which critically depends on stability of these mapping. This
+		 * stability is not a requirement for STRUCT/UNION equivalence
+		 * checks, though.
+		 */
+
+		/* if it's the split BTF case, we still need to point base FWD
+		 * to STRUCT/UNION in a split BTF, because FWDs from split BTF
+		 * will be resolved against base FWD. If we don't point base
+		 * canonical FWD to the resolved STRUCT/UNION, then all the
+		 * FWDs in split BTF won't be correctly resolved to a proper
+		 * STRUCT/UNION.
+		 */
+		if (t_kind != BTF_KIND_FWD && c_kind == BTF_KIND_FWD)
+			d->map[c_id] = t_id;
+
+		/* if graph equivalence determined that we'd need to adjust
+		 * base canonical types, then we need to only point base FWDs
+		 * to STRUCTs/UNIONs and do no more modifications. For all
+		 * other purposes the type graphs were not equivalent.
+		 */
+		if (d->hypot_adjust_canon)
+			continue;
+
+		if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD)
+			d->map[t_id] = c_id;
+
+		if ((t_kind == BTF_KIND_STRUCT || t_kind == BTF_KIND_UNION) &&
+		    c_kind != BTF_KIND_FWD &&
+		    is_type_mapped(d, c_id) &&
+		    !is_type_mapped(d, t_id)) {
+			/*
+			 * as a perf optimization, we can map struct/union
+			 * that's part of type graph we just verified for
+			 * equivalence. We can do that for struct/union that has
+			 * canonical representative only, though.
+			 */
+			d->map[t_id] = c_id;
+		}
+	}
+}
+
+/*
+ * Deduplicate struct/union types.
+ *
+ * For each struct/union type its type signature hash is calculated, taking
+ * into account type's name, size, number, order and names of fields, but
+ * ignoring type ID's referenced from fields, because they might not be deduped
+ * completely until after reference types deduplication phase. This type hash
+ * is used to iterate over all potential canonical types, sharing same hash.
+ * For each canonical candidate we check whether type graphs that they form
+ * (through referenced types in fields and so on) are equivalent using algorithm
+ * implemented in `btf_dedup_is_equiv`. If such equivalence is found and
+ * BTF_KIND_FWD resolution is allowed, then hypothetical mapping
+ * (btf_dedup->hypot_map) produced by aforementioned type graph equivalence
+ * algorithm is used to record FWD -> STRUCT/UNION mapping. It's also used to
+ * potentially map other structs/unions to their canonical representatives,
+ * if such relationship hasn't yet been established. This speeds up algorithm
+ * by eliminating some of the duplicate work.
+ *
+ * If no matching canonical representative was found, struct/union is marked
+ * as canonical for itself and is added into btf_dedup->dedup_table hash map
+ * for further look ups.
+ */
+static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
+{
+	struct btf_type *cand_type, *t;
+	struct hashmap_entry *hash_entry;
+	/* if we don't find equivalent type, then we are canonical */
+	__u32 new_id = type_id;
+	__u16 kind;
+	long h;
+
+	/* already deduped or is in process of deduping (loop detected) */
+	if (d->map[type_id] <= BTF_MAX_NR_TYPES)
+		return 0;
+
+	t = btf_type_by_id(d->btf, type_id);
+	kind = btf_kind(t);
+
+	if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
+		return 0;
+
+	h = btf_hash_struct(t);
+	for_each_dedup_cand(d, hash_entry, h) {
+		__u32 cand_id = hash_entry->value;
+		int eq;
+
+		/*
+		 * Even though btf_dedup_is_equiv() checks for
+		 * btf_shallow_equal_struct() internally when checking two
+		 * structs (unions) for equivalence, we need to guard here
+		 * from picking matching FWD type as a dedup candidate.
+		 * This can happen due to hash collision. In such case just
+		 * relying on btf_dedup_is_equiv() would lead to potentially
+		 * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because
+		 * FWD and compatible STRUCT/UNION are considered equivalent.
+		 */
+		cand_type = btf_type_by_id(d->btf, cand_id);
+		if (!btf_shallow_equal_struct(t, cand_type))
+			continue;
+
+		btf_dedup_clear_hypot_map(d);
+		eq = btf_dedup_is_equiv(d, type_id, cand_id);
+		if (eq < 0)
+			return eq;
+		if (!eq)
+			continue;
+		btf_dedup_merge_hypot_map(d);
+		if (d->hypot_adjust_canon) /* not really equivalent */
+			continue;
+		new_id = cand_id;
+		break;
+	}
+
+	d->map[type_id] = new_id;
+	if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int btf_dedup_struct_types(struct btf_dedup *d)
+{
+	int i, err;
+
+	for (i = 0; i < d->btf->nr_types; i++) {
+		err = btf_dedup_struct_type(d, d->btf->start_id + i);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+/*
+ * Deduplicate reference type.
+ *
+ * Once all primitive and struct/union types got deduplicated, we can easily
+ * deduplicate all other (reference) BTF types. This is done in two steps:
+ *
+ * 1. Resolve all referenced type IDs into their canonical type IDs. This
+ * resolution can be done either immediately for primitive or struct/union types
+ * (because they were deduped in previous two phases) or recursively for
+ * reference types. Recursion will always terminate at either primitive or
+ * struct/union type, at which point we can "unwind" chain of reference types
+ * one by one. There is no danger of encountering cycles because in C type
+ * system the only way to form type cycle is through struct/union, so any chain
+ * of reference types, even those taking part in a type cycle, will inevitably
+ * reach struct/union at some point.
+ *
+ * 2. Once all referenced type IDs are resolved into canonical ones, BTF type
+ * becomes "stable", in the sense that no further deduplication will cause
+ * any changes to it. With that, it's now possible to calculate type's signature
+ * hash (this time taking into account referenced type IDs) and loop over all
+ * potential canonical representatives. If no match was found, current type
+ * will become canonical representative of itself and will be added into
+ * btf_dedup->dedup_table as another possible canonical representative.
+ */
+static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
+{
+	struct hashmap_entry *hash_entry;
+	__u32 new_id = type_id, cand_id;
+	struct btf_type *t, *cand;
+	/* if we don't find equivalent type, then we are representative type */
+	int ref_type_id;
+	long h;
+
+	if (d->map[type_id] == BTF_IN_PROGRESS_ID)
+		return -ELOOP;
+	if (d->map[type_id] <= BTF_MAX_NR_TYPES)
+		return resolve_type_id(d, type_id);
+
+	t = btf_type_by_id(d->btf, type_id);
+	d->map[type_id] = BTF_IN_PROGRESS_ID;
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_CONST:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_FUNC:
+	case BTF_KIND_TYPE_TAG:
+		ref_type_id = btf_dedup_ref_type(d, t->type);
+		if (ref_type_id < 0)
+			return ref_type_id;
+		t->type = ref_type_id;
+
+		h = btf_hash_common(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = hash_entry->value;
+			cand = btf_type_by_id(d->btf, cand_id);
+			if (btf_equal_common(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+
+	case BTF_KIND_DECL_TAG:
+		ref_type_id = btf_dedup_ref_type(d, t->type);
+		if (ref_type_id < 0)
+			return ref_type_id;
+		t->type = ref_type_id;
+
+		h = btf_hash_int_decl_tag(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = hash_entry->value;
+			cand = btf_type_by_id(d->btf, cand_id);
+			if (btf_equal_int_tag(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+
+	case BTF_KIND_ARRAY: {
+		struct btf_array *info = btf_array(t);
+
+		ref_type_id = btf_dedup_ref_type(d, info->type);
+		if (ref_type_id < 0)
+			return ref_type_id;
+		info->type = ref_type_id;
+
+		ref_type_id = btf_dedup_ref_type(d, info->index_type);
+		if (ref_type_id < 0)
+			return ref_type_id;
+		info->index_type = ref_type_id;
+
+		h = btf_hash_array(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = hash_entry->value;
+			cand = btf_type_by_id(d->btf, cand_id);
+			if (btf_equal_array(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+	}
+
+	case BTF_KIND_FUNC_PROTO: {
+		struct btf_param *param;
+		__u16 vlen;
+		int i;
+
+		ref_type_id = btf_dedup_ref_type(d, t->type);
+		if (ref_type_id < 0)
+			return ref_type_id;
+		t->type = ref_type_id;
+
+		vlen = btf_vlen(t);
+		param = btf_params(t);
+		for (i = 0; i < vlen; i++) {
+			ref_type_id = btf_dedup_ref_type(d, param->type);
+			if (ref_type_id < 0)
+				return ref_type_id;
+			param->type = ref_type_id;
+			param++;
+		}
+
+		h = btf_hash_fnproto(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = hash_entry->value;
+			cand = btf_type_by_id(d->btf, cand_id);
+			if (btf_equal_fnproto(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+	}
+
+	default:
+		return -EINVAL;
+	}
+
+	d->map[type_id] = new_id;
+	if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+		return -ENOMEM;
+
+	return new_id;
+}
+
+static int btf_dedup_ref_types(struct btf_dedup *d)
+{
+	int i, err;
+
+	for (i = 0; i < d->btf->nr_types; i++) {
+		err = btf_dedup_ref_type(d, d->btf->start_id + i);
+		if (err < 0)
+			return err;
+	}
+	/* we won't need d->dedup_table anymore */
+	hashmap__free(d->dedup_table);
+	d->dedup_table = NULL;
+	return 0;
+}
+
+/*
+ * Collect a map from type names to type ids for all canonical structs
+ * and unions. If the same name is shared by several canonical types
+ * use a special value 0 to indicate this fact.
+ */
+static int btf_dedup_fill_unique_names_map(struct btf_dedup *d, struct hashmap *names_map)
+{
+	__u32 nr_types = btf__type_cnt(d->btf);
+	struct btf_type *t;
+	__u32 type_id;
+	__u16 kind;
+	int err;
+
+	/*
+	 * Iterate over base and split module ids in order to get all
+	 * available structs in the map.
+	 */
+	for (type_id = 1; type_id < nr_types; ++type_id) {
+		t = btf_type_by_id(d->btf, type_id);
+		kind = btf_kind(t);
+
+		if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
+			continue;
+
+		/* Skip non-canonical types */
+		if (type_id != d->map[type_id])
+			continue;
+
+		err = hashmap__add(names_map, t->name_off, type_id);
+		if (err == -EEXIST)
+			err = hashmap__set(names_map, t->name_off, 0, NULL, NULL);
+
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int btf_dedup_resolve_fwd(struct btf_dedup *d, struct hashmap *names_map, __u32 type_id)
+{
+	struct btf_type *t = btf_type_by_id(d->btf, type_id);
+	enum btf_fwd_kind fwd_kind = btf_kflag(t);
+	__u16 cand_kind, kind = btf_kind(t);
+	struct btf_type *cand_t;
+	uintptr_t cand_id;
+
+	if (kind != BTF_KIND_FWD)
+		return 0;
+
+	/* Skip if this FWD already has a mapping */
+	if (type_id != d->map[type_id])
+		return 0;
+
+	if (!hashmap__find(names_map, t->name_off, &cand_id))
+		return 0;
+
+	/* Zero is a special value indicating that name is not unique */
+	if (!cand_id)
+		return 0;
+
+	cand_t = btf_type_by_id(d->btf, cand_id);
+	cand_kind = btf_kind(cand_t);
+	if ((cand_kind == BTF_KIND_STRUCT && fwd_kind != BTF_FWD_STRUCT) ||
+	    (cand_kind == BTF_KIND_UNION && fwd_kind != BTF_FWD_UNION))
+		return 0;
+
+	d->map[type_id] = cand_id;
+
+	return 0;
+}
+
+/*
+ * Resolve unambiguous forward declarations.
+ *
+ * The lion's share of all FWD declarations is resolved during
+ * `btf_dedup_struct_types` phase when different type graphs are
+ * compared against each other. However, if in some compilation unit a
+ * FWD declaration is not a part of a type graph compared against
+ * another type graph that declaration's canonical type would not be
+ * changed. Example:
+ *
+ * CU #1:
+ *
+ * struct foo;
+ * struct foo *some_global;
+ *
+ * CU #2:
+ *
+ * struct foo { int u; };
+ * struct foo *another_global;
+ *
+ * After `btf_dedup_struct_types` the BTF looks as follows:
+ *
+ * [1] STRUCT 'foo' size=4 vlen=1 ...
+ * [2] INT 'int' size=4 ...
+ * [3] PTR '(anon)' type_id=1
+ * [4] FWD 'foo' fwd_kind=struct
+ * [5] PTR '(anon)' type_id=4
+ *
+ * This pass assumes that such FWD declarations should be mapped to
+ * structs or unions with identical name in case if the name is not
+ * ambiguous.
+ */
+static int btf_dedup_resolve_fwds(struct btf_dedup *d)
+{
+	int i, err;
+	struct hashmap *names_map;
+
+	names_map = hashmap__new(btf_dedup_identity_hash_fn, btf_dedup_equal_fn, NULL);
+	if (IS_ERR(names_map))
+		return PTR_ERR(names_map);
+
+	err = btf_dedup_fill_unique_names_map(d, names_map);
+	if (err < 0)
+		goto exit;
+
+	for (i = 0; i < d->btf->nr_types; i++) {
+		err = btf_dedup_resolve_fwd(d, names_map, d->btf->start_id + i);
+		if (err < 0)
+			break;
+	}
+
+exit:
+	hashmap__free(names_map);
+	return err;
+}
+
+/*
+ * Compact types.
+ *
+ * After we established for each type its corresponding canonical representative
+ * type, we now can eliminate types that are not canonical and leave only
+ * canonical ones layed out sequentially in memory by copying them over
+ * duplicates. During compaction btf_dedup->hypot_map array is reused to store
+ * a map from original type ID to a new compacted type ID, which will be used
+ * during next phase to "fix up" type IDs, referenced from struct/union and
+ * reference types.
+ */
+static int btf_dedup_compact_types(struct btf_dedup *d)
+{
+	__u32 *new_offs;
+	__u32 next_type_id = d->btf->start_id;
+	const struct btf_type *t;
+	void *p;
+	int i, id, len;
+
+	/* we are going to reuse hypot_map to store compaction remapping */
+	d->hypot_map[0] = 0;
+	/* base BTF types are not renumbered */
+	for (id = 1; id < d->btf->start_id; id++)
+		d->hypot_map[id] = id;
+	for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++)
+		d->hypot_map[id] = BTF_UNPROCESSED_ID;
+
+	p = d->btf->types_data;
+
+	for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++) {
+		if (d->map[id] != id)
+			continue;
+
+		t = btf__type_by_id(d->btf, id);
+		len = btf_type_size(t);
+		if (len < 0)
+			return len;
+
+		memmove(p, t, len);
+		d->hypot_map[id] = next_type_id;
+		d->btf->type_offs[next_type_id - d->btf->start_id] = p - d->btf->types_data;
+		p += len;
+		next_type_id++;
+	}
+
+	/* shrink struct btf's internal types index and update btf_header */
+	d->btf->nr_types = next_type_id - d->btf->start_id;
+	d->btf->type_offs_cap = d->btf->nr_types;
+	d->btf->hdr->type_len = p - d->btf->types_data;
+	new_offs = libbpf_reallocarray(d->btf->type_offs, d->btf->type_offs_cap,
+				       sizeof(*new_offs));
+	if (d->btf->type_offs_cap && !new_offs)
+		return -ENOMEM;
+	d->btf->type_offs = new_offs;
+	d->btf->hdr->str_off = d->btf->hdr->type_len;
+	d->btf->raw_size = d->btf->hdr->hdr_len + d->btf->hdr->type_len + d->btf->hdr->str_len;
+	return 0;
+}
+
+/*
+ * Figure out final (deduplicated and compacted) type ID for provided original
+ * `type_id` by first resolving it into corresponding canonical type ID and
+ * then mapping it to a deduplicated type ID, stored in btf_dedup->hypot_map,
+ * which is populated during compaction phase.
+ */
+static int btf_dedup_remap_type_id(__u32 *type_id, void *ctx)
+{
+	struct btf_dedup *d = ctx;
+	__u32 resolved_type_id, new_type_id;
+
+	resolved_type_id = resolve_type_id(d, *type_id);
+	new_type_id = d->hypot_map[resolved_type_id];
+	if (new_type_id > BTF_MAX_NR_TYPES)
+		return -EINVAL;
+
+	*type_id = new_type_id;
+	return 0;
+}
+
+/*
+ * Remap referenced type IDs into deduped type IDs.
+ *
+ * After BTF types are deduplicated and compacted, their final type IDs may
+ * differ from original ones. The map from original to a corresponding
+ * deduped type ID is stored in btf_dedup->hypot_map and is populated during
+ * compaction phase. During remapping phase we are rewriting all type IDs
+ * referenced from any BTF type (e.g., struct fields, func proto args, etc) to
+ * their final deduped type IDs.
+ */
+static int btf_dedup_remap_types(struct btf_dedup *d)
+{
+	int i, r;
+
+	for (i = 0; i < d->btf->nr_types; i++) {
+		struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
+
+		r = btf_type_visit_type_ids(t, btf_dedup_remap_type_id, d);
+		if (r)
+			return r;
+	}
+
+	if (!d->btf_ext)
+		return 0;
+
+	r = btf_ext_visit_type_ids(d->btf_ext, btf_dedup_remap_type_id, d);
+	if (r)
+		return r;
+
+	return 0;
+}
+
+/*
+ * Probe few well-known locations for vmlinux kernel image and try to load BTF
+ * data out of it to use for target BTF.
+ */
+struct btf *btf__load_vmlinux_btf(void)
+{
+	const char *locations[] = {
+		/* try canonical vmlinux BTF through sysfs first */
+		"/sys/kernel/btf/vmlinux",
+		/* fall back to trying to find vmlinux on disk otherwise */
+		"/boot/vmlinux-%1$s",
+		"/lib/modules/%1$s/vmlinux-%1$s",
+		"/lib/modules/%1$s/build/vmlinux",
+		"/usr/lib/modules/%1$s/kernel/vmlinux",
+		"/usr/lib/debug/boot/vmlinux-%1$s",
+		"/usr/lib/debug/boot/vmlinux-%1$s.debug",
+		"/usr/lib/debug/lib/modules/%1$s/vmlinux",
+	};
+	char path[PATH_MAX + 1];
+	struct utsname buf;
+	struct btf *btf;
+	int i, err;
+
+	uname(&buf);
+
+	for (i = 0; i < ARRAY_SIZE(locations); i++) {
+		snprintf(path, PATH_MAX, locations[i], buf.release);
+
+		if (faccessat(AT_FDCWD, path, R_OK, AT_EACCESS))
+			continue;
+
+		btf = btf__parse(path, NULL);
+		err = libbpf_get_error(btf);
+		pr_debug("loading kernel BTF '%s': %d\n", path, err);
+		if (err)
+			continue;
+
+		return btf;
+	}
+
+	pr_warn("failed to find valid kernel BTF\n");
+	return libbpf_err_ptr(-ESRCH);
+}
+
+struct btf *libbpf_find_kernel_btf(void) __attribute__((alias("btf__load_vmlinux_btf")));
+
+struct btf *btf__load_module_btf(const char *module_name, struct btf *vmlinux_btf)
+{
+	char path[80];
+
+	snprintf(path, sizeof(path), "/sys/kernel/btf/%s", module_name);
+	return btf__parse_split(path, vmlinux_btf);
+}
+
+int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx)
+{
+	int i, n, err;
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_INT:
+	case BTF_KIND_FLOAT:
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		return 0;
+
+	case BTF_KIND_FWD:
+	case BTF_KIND_CONST:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_FUNC:
+	case BTF_KIND_VAR:
+	case BTF_KIND_DECL_TAG:
+	case BTF_KIND_TYPE_TAG:
+		return visit(&t->type, ctx);
+
+	case BTF_KIND_ARRAY: {
+		struct btf_array *a = btf_array(t);
+
+		err = visit(&a->type, ctx);
+		err = err ?: visit(&a->index_type, ctx);
+		return err;
+	}
+
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		struct btf_member *m = btf_members(t);
+
+		for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+			err = visit(&m->type, ctx);
+			if (err)
+				return err;
+		}
+		return 0;
+	}
+
+	case BTF_KIND_FUNC_PROTO: {
+		struct btf_param *m = btf_params(t);
+
+		err = visit(&t->type, ctx);
+		if (err)
+			return err;
+		for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+			err = visit(&m->type, ctx);
+			if (err)
+				return err;
+		}
+		return 0;
+	}
+
+	case BTF_KIND_DATASEC: {
+		struct btf_var_secinfo *m = btf_var_secinfos(t);
+
+		for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+			err = visit(&m->type, ctx);
+			if (err)
+				return err;
+		}
+		return 0;
+	}
+
+	default:
+		return -EINVAL;
+	}
+}
+
+int btf_type_visit_str_offs(struct btf_type *t, str_off_visit_fn visit, void *ctx)
+{
+	int i, n, err;
+
+	err = visit(&t->name_off, ctx);
+	if (err)
+		return err;
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		struct btf_member *m = btf_members(t);
+
+		for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+			err = visit(&m->name_off, ctx);
+			if (err)
+				return err;
+		}
+		break;
+	}
+	case BTF_KIND_ENUM: {
+		struct btf_enum *m = btf_enum(t);
+
+		for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+			err = visit(&m->name_off, ctx);
+			if (err)
+				return err;
+		}
+		break;
+	}
+	case BTF_KIND_ENUM64: {
+		struct btf_enum64 *m = btf_enum64(t);
+
+		for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+			err = visit(&m->name_off, ctx);
+			if (err)
+				return err;
+		}
+		break;
+	}
+	case BTF_KIND_FUNC_PROTO: {
+		struct btf_param *m = btf_params(t);
+
+		for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
+			err = visit(&m->name_off, ctx);
+			if (err)
+				return err;
+		}
+		break;
+	}
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+int btf_ext_visit_type_ids(struct btf_ext *btf_ext, type_id_visit_fn visit, void *ctx)
+{
+	const struct btf_ext_info *seg;
+	struct btf_ext_info_sec *sec;
+	int i, err;
+
+	seg = &btf_ext->func_info;
+	for_each_btf_ext_sec(seg, sec) {
+		struct bpf_func_info_min *rec;
+
+		for_each_btf_ext_rec(seg, sec, i, rec) {
+			err = visit(&rec->type_id, ctx);
+			if (err < 0)
+				return err;
+		}
+	}
+
+	seg = &btf_ext->core_relo_info;
+	for_each_btf_ext_sec(seg, sec) {
+		struct bpf_core_relo *rec;
+
+		for_each_btf_ext_rec(seg, sec, i, rec) {
+			err = visit(&rec->type_id, ctx);
+			if (err < 0)
+				return err;
+		}
+	}
+
+	return 0;
+}
+
+int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void *ctx)
+{
+	const struct btf_ext_info *seg;
+	struct btf_ext_info_sec *sec;
+	int i, err;
+
+	seg = &btf_ext->func_info;
+	for_each_btf_ext_sec(seg, sec) {
+		err = visit(&sec->sec_name_off, ctx);
+		if (err)
+			return err;
+	}
+
+	seg = &btf_ext->line_info;
+	for_each_btf_ext_sec(seg, sec) {
+		struct bpf_line_info_min *rec;
+
+		err = visit(&sec->sec_name_off, ctx);
+		if (err)
+			return err;
+
+		for_each_btf_ext_rec(seg, sec, i, rec) {
+			err = visit(&rec->file_name_off, ctx);
+			if (err)
+				return err;
+			err = visit(&rec->line_off, ctx);
+			if (err)
+				return err;
+		}
+	}
+
+	seg = &btf_ext->core_relo_info;
+	for_each_btf_ext_sec(seg, sec) {
+		struct bpf_core_relo *rec;
+
+		err = visit(&sec->sec_name_off, ctx);
+		if (err)
+			return err;
+
+		for_each_btf_ext_rec(seg, sec, i, rec) {
+			err = visit(&rec->access_str_off, ctx);
+			if (err)
+				return err;
+		}
+	}
+
+	return 0;
+}
diff --git a/src/btf.h b/src/btf.h
new file mode 100644
index 0000000..8e6880d
--- /dev/null
+++ b/src/btf.h
@@ -0,0 +1,575 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/* Copyright (c) 2018 Facebook */
+/*! \file */
+
+#ifndef __LIBBPF_BTF_H
+#define __LIBBPF_BTF_H
+
+#include <stdarg.h>
+#include <stdbool.h>
+#include <linux/btf.h>
+#include <linux/types.h>
+
+#include "libbpf_common.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define BTF_ELF_SEC ".BTF"
+#define BTF_EXT_ELF_SEC ".BTF.ext"
+#define MAPS_ELF_SEC ".maps"
+
+struct btf;
+struct btf_ext;
+struct btf_type;
+
+struct bpf_object;
+
+enum btf_endianness {
+	BTF_LITTLE_ENDIAN = 0,
+	BTF_BIG_ENDIAN = 1,
+};
+
+/**
+ * @brief **btf__free()** frees all data of a BTF object
+ * @param btf BTF object to free
+ */
+LIBBPF_API void btf__free(struct btf *btf);
+
+/**
+ * @brief **btf__new()** creates a new instance of a BTF object from the raw
+ * bytes of an ELF's BTF section
+ * @param data raw bytes
+ * @param size number of bytes passed in `data`
+ * @return new BTF object instance which has to be eventually freed with
+ * **btf__free()**
+ *
+ * On error, error-code-encoded-as-pointer is returned, not a NULL. To extract
+ * error code from such a pointer `libbpf_get_error()` should be used. If
+ * `libbpf_set_strict_mode(LIBBPF_STRICT_CLEAN_PTRS)` is enabled, NULL is
+ * returned on error instead. In both cases thread-local `errno` variable is
+ * always set to error code as well.
+ */
+LIBBPF_API struct btf *btf__new(const void *data, __u32 size);
+
+/**
+ * @brief **btf__new_split()** create a new instance of a BTF object from the
+ * provided raw data bytes. It takes another BTF instance, **base_btf**, which
+ * serves as a base BTF, which is extended by types in a newly created BTF
+ * instance
+ * @param data raw bytes
+ * @param size length of raw bytes
+ * @param base_btf the base BTF object
+ * @return new BTF object instance which has to be eventually freed with
+ * **btf__free()**
+ *
+ * If *base_btf* is NULL, `btf__new_split()` is equivalent to `btf__new()` and
+ * creates non-split BTF.
+ *
+ * On error, error-code-encoded-as-pointer is returned, not a NULL. To extract
+ * error code from such a pointer `libbpf_get_error()` should be used. If
+ * `libbpf_set_strict_mode(LIBBPF_STRICT_CLEAN_PTRS)` is enabled, NULL is
+ * returned on error instead. In both cases thread-local `errno` variable is
+ * always set to error code as well.
+ */
+LIBBPF_API struct btf *btf__new_split(const void *data, __u32 size, struct btf *base_btf);
+
+/**
+ * @brief **btf__new_empty()** creates an empty BTF object.  Use
+ * `btf__add_*()` to populate such BTF object.
+ * @return new BTF object instance which has to be eventually freed with
+ * **btf__free()**
+ *
+ * On error, error-code-encoded-as-pointer is returned, not a NULL. To extract
+ * error code from such a pointer `libbpf_get_error()` should be used. If
+ * `libbpf_set_strict_mode(LIBBPF_STRICT_CLEAN_PTRS)` is enabled, NULL is
+ * returned on error instead. In both cases thread-local `errno` variable is
+ * always set to error code as well.
+ */
+LIBBPF_API struct btf *btf__new_empty(void);
+
+/**
+ * @brief **btf__new_empty_split()** creates an unpopulated BTF object from an
+ * ELF BTF section except with a base BTF on top of which split BTF should be
+ * based
+ * @return new BTF object instance which has to be eventually freed with
+ * **btf__free()**
+ *
+ * If *base_btf* is NULL, `btf__new_empty_split()` is equivalent to
+ * `btf__new_empty()` and creates non-split BTF.
+ *
+ * On error, error-code-encoded-as-pointer is returned, not a NULL. To extract
+ * error code from such a pointer `libbpf_get_error()` should be used. If
+ * `libbpf_set_strict_mode(LIBBPF_STRICT_CLEAN_PTRS)` is enabled, NULL is
+ * returned on error instead. In both cases thread-local `errno` variable is
+ * always set to error code as well.
+ */
+LIBBPF_API struct btf *btf__new_empty_split(struct btf *base_btf);
+
+LIBBPF_API struct btf *btf__parse(const char *path, struct btf_ext **btf_ext);
+LIBBPF_API struct btf *btf__parse_split(const char *path, struct btf *base_btf);
+LIBBPF_API struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext);
+LIBBPF_API struct btf *btf__parse_elf_split(const char *path, struct btf *base_btf);
+LIBBPF_API struct btf *btf__parse_raw(const char *path);
+LIBBPF_API struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf);
+
+LIBBPF_API struct btf *btf__load_vmlinux_btf(void);
+LIBBPF_API struct btf *btf__load_module_btf(const char *module_name, struct btf *vmlinux_btf);
+
+LIBBPF_API struct btf *btf__load_from_kernel_by_id(__u32 id);
+LIBBPF_API struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf);
+
+LIBBPF_API int btf__load_into_kernel(struct btf *btf);
+LIBBPF_API __s32 btf__find_by_name(const struct btf *btf,
+				   const char *type_name);
+LIBBPF_API __s32 btf__find_by_name_kind(const struct btf *btf,
+					const char *type_name, __u32 kind);
+LIBBPF_API __u32 btf__type_cnt(const struct btf *btf);
+LIBBPF_API const struct btf *btf__base_btf(const struct btf *btf);
+LIBBPF_API const struct btf_type *btf__type_by_id(const struct btf *btf,
+						  __u32 id);
+LIBBPF_API size_t btf__pointer_size(const struct btf *btf);
+LIBBPF_API int btf__set_pointer_size(struct btf *btf, size_t ptr_sz);
+LIBBPF_API enum btf_endianness btf__endianness(const struct btf *btf);
+LIBBPF_API int btf__set_endianness(struct btf *btf, enum btf_endianness endian);
+LIBBPF_API __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
+LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);
+LIBBPF_API int btf__align_of(const struct btf *btf, __u32 id);
+LIBBPF_API int btf__fd(const struct btf *btf);
+LIBBPF_API void btf__set_fd(struct btf *btf, int fd);
+LIBBPF_API const void *btf__raw_data(const struct btf *btf, __u32 *size);
+LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
+LIBBPF_API const char *btf__str_by_offset(const struct btf *btf, __u32 offset);
+
+LIBBPF_API struct btf_ext *btf_ext__new(const __u8 *data, __u32 size);
+LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext);
+LIBBPF_API const void *btf_ext__raw_data(const struct btf_ext *btf_ext, __u32 *size);
+
+LIBBPF_API int btf__find_str(struct btf *btf, const char *s);
+LIBBPF_API int btf__add_str(struct btf *btf, const char *s);
+LIBBPF_API int btf__add_type(struct btf *btf, const struct btf *src_btf,
+			     const struct btf_type *src_type);
+/**
+ * @brief **btf__add_btf()** appends all the BTF types from *src_btf* into *btf*
+ * @param btf BTF object which all the BTF types and strings are added to
+ * @param src_btf BTF object which all BTF types and referenced strings are copied from
+ * @return BTF type ID of the first appended BTF type, or negative error code
+ *
+ * **btf__add_btf()** can be used to simply and efficiently append the entire
+ * contents of one BTF object to another one. All the BTF type data is copied
+ * over, all referenced type IDs are adjusted by adding a necessary ID offset.
+ * Only strings referenced from BTF types are copied over and deduplicated, so
+ * if there were some unused strings in *src_btf*, those won't be copied over,
+ * which is consistent with the general string deduplication semantics of BTF
+ * writing APIs.
+ *
+ * If any error is encountered during this process, the contents of *btf* is
+ * left intact, which means that **btf__add_btf()** follows the transactional
+ * semantics and the operation as a whole is all-or-nothing.
+ *
+ * *src_btf* has to be non-split BTF, as of now copying types from split BTF
+ * is not supported and will result in -ENOTSUP error code returned.
+ */
+LIBBPF_API int btf__add_btf(struct btf *btf, const struct btf *src_btf);
+
+LIBBPF_API int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding);
+LIBBPF_API int btf__add_float(struct btf *btf, const char *name, size_t byte_sz);
+LIBBPF_API int btf__add_ptr(struct btf *btf, int ref_type_id);
+LIBBPF_API int btf__add_array(struct btf *btf,
+			      int index_type_id, int elem_type_id, __u32 nr_elems);
+/* struct/union construction APIs */
+LIBBPF_API int btf__add_struct(struct btf *btf, const char *name, __u32 sz);
+LIBBPF_API int btf__add_union(struct btf *btf, const char *name, __u32 sz);
+LIBBPF_API int btf__add_field(struct btf *btf, const char *name, int field_type_id,
+			      __u32 bit_offset, __u32 bit_size);
+
+/* enum construction APIs */
+LIBBPF_API int btf__add_enum(struct btf *btf, const char *name, __u32 bytes_sz);
+LIBBPF_API int btf__add_enum_value(struct btf *btf, const char *name, __s64 value);
+LIBBPF_API int btf__add_enum64(struct btf *btf, const char *name, __u32 bytes_sz, bool is_signed);
+LIBBPF_API int btf__add_enum64_value(struct btf *btf, const char *name, __u64 value);
+
+enum btf_fwd_kind {
+	BTF_FWD_STRUCT = 0,
+	BTF_FWD_UNION = 1,
+	BTF_FWD_ENUM = 2,
+};
+
+LIBBPF_API int btf__add_fwd(struct btf *btf, const char *name, enum btf_fwd_kind fwd_kind);
+LIBBPF_API int btf__add_typedef(struct btf *btf, const char *name, int ref_type_id);
+LIBBPF_API int btf__add_volatile(struct btf *btf, int ref_type_id);
+LIBBPF_API int btf__add_const(struct btf *btf, int ref_type_id);
+LIBBPF_API int btf__add_restrict(struct btf *btf, int ref_type_id);
+LIBBPF_API int btf__add_type_tag(struct btf *btf, const char *value, int ref_type_id);
+
+/* func and func_proto construction APIs */
+LIBBPF_API int btf__add_func(struct btf *btf, const char *name,
+			     enum btf_func_linkage linkage, int proto_type_id);
+LIBBPF_API int btf__add_func_proto(struct btf *btf, int ret_type_id);
+LIBBPF_API int btf__add_func_param(struct btf *btf, const char *name, int type_id);
+
+/* var & datasec construction APIs */
+LIBBPF_API int btf__add_var(struct btf *btf, const char *name, int linkage, int type_id);
+LIBBPF_API int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz);
+LIBBPF_API int btf__add_datasec_var_info(struct btf *btf, int var_type_id,
+					 __u32 offset, __u32 byte_sz);
+
+/* tag construction API */
+LIBBPF_API int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
+			    int component_idx);
+
+struct btf_dedup_opts {
+	size_t sz;
+	/* optional .BTF.ext info to dedup along the main BTF info */
+	struct btf_ext *btf_ext;
+	/* force hash collisions (used for testing) */
+	bool force_collisions;
+	size_t :0;
+};
+#define btf_dedup_opts__last_field force_collisions
+
+LIBBPF_API int btf__dedup(struct btf *btf, const struct btf_dedup_opts *opts);
+
+struct btf_dump;
+
+struct btf_dump_opts {
+	size_t sz;
+};
+#define btf_dump_opts__last_field sz
+
+typedef void (*btf_dump_printf_fn_t)(void *ctx, const char *fmt, va_list args);
+
+LIBBPF_API struct btf_dump *btf_dump__new(const struct btf *btf,
+					  btf_dump_printf_fn_t printf_fn,
+					  void *ctx,
+					  const struct btf_dump_opts *opts);
+
+LIBBPF_API void btf_dump__free(struct btf_dump *d);
+
+LIBBPF_API int btf_dump__dump_type(struct btf_dump *d, __u32 id);
+
+struct btf_dump_emit_type_decl_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* optional field name for type declaration, e.g.:
+	 * - struct my_struct <FNAME>
+	 * - void (*<FNAME>)(int)
+	 * - char (*<FNAME>)[123]
+	 */
+	const char *field_name;
+	/* extra indentation level (in number of tabs) to emit for multi-line
+	 * type declarations (e.g., anonymous struct); applies for lines
+	 * starting from the second one (first line is assumed to have
+	 * necessary indentation already
+	 */
+	int indent_level;
+	/* strip all the const/volatile/restrict mods */
+	bool strip_mods;
+	size_t :0;
+};
+#define btf_dump_emit_type_decl_opts__last_field strip_mods
+
+LIBBPF_API int
+btf_dump__emit_type_decl(struct btf_dump *d, __u32 id,
+			 const struct btf_dump_emit_type_decl_opts *opts);
+
+
+struct btf_dump_type_data_opts {
+	/* size of this struct, for forward/backward compatibility */
+	size_t sz;
+	const char *indent_str;
+	int indent_level;
+	/* below match "show" flags for bpf_show_snprintf() */
+	bool compact;		/* no newlines/indentation */
+	bool skip_names;	/* skip member/type names */
+	bool emit_zeroes;	/* show 0-valued fields */
+	size_t :0;
+};
+#define btf_dump_type_data_opts__last_field emit_zeroes
+
+LIBBPF_API int
+btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
+			 const void *data, size_t data_sz,
+			 const struct btf_dump_type_data_opts *opts);
+
+/*
+ * A set of helpers for easier BTF types handling.
+ *
+ * The inline functions below rely on constants from the kernel headers which
+ * may not be available for applications including this header file. To avoid
+ * compilation errors, we define all the constants here that were added after
+ * the initial introduction of the BTF_KIND* constants.
+ */
+#ifndef BTF_KIND_FUNC
+#define BTF_KIND_FUNC		12	/* Function	*/
+#define BTF_KIND_FUNC_PROTO	13	/* Function Proto	*/
+#endif
+#ifndef BTF_KIND_VAR
+#define BTF_KIND_VAR		14	/* Variable	*/
+#define BTF_KIND_DATASEC	15	/* Section	*/
+#endif
+#ifndef BTF_KIND_FLOAT
+#define BTF_KIND_FLOAT		16	/* Floating point	*/
+#endif
+/* The kernel header switched to enums, so the following were never #defined */
+#define BTF_KIND_DECL_TAG	17	/* Decl Tag */
+#define BTF_KIND_TYPE_TAG	18	/* Type Tag */
+#define BTF_KIND_ENUM64		19	/* Enum for up-to 64bit values */
+
+static inline __u16 btf_kind(const struct btf_type *t)
+{
+	return BTF_INFO_KIND(t->info);
+}
+
+static inline __u16 btf_vlen(const struct btf_type *t)
+{
+	return BTF_INFO_VLEN(t->info);
+}
+
+static inline bool btf_kflag(const struct btf_type *t)
+{
+	return BTF_INFO_KFLAG(t->info);
+}
+
+static inline bool btf_is_void(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_UNKN;
+}
+
+static inline bool btf_is_int(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_INT;
+}
+
+static inline bool btf_is_ptr(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_PTR;
+}
+
+static inline bool btf_is_array(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_ARRAY;
+}
+
+static inline bool btf_is_struct(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_STRUCT;
+}
+
+static inline bool btf_is_union(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_UNION;
+}
+
+static inline bool btf_is_composite(const struct btf_type *t)
+{
+	__u16 kind = btf_kind(t);
+
+	return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
+}
+
+static inline bool btf_is_enum(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_ENUM;
+}
+
+static inline bool btf_is_enum64(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_ENUM64;
+}
+
+static inline bool btf_is_fwd(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_FWD;
+}
+
+static inline bool btf_is_typedef(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_TYPEDEF;
+}
+
+static inline bool btf_is_volatile(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_VOLATILE;
+}
+
+static inline bool btf_is_const(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_CONST;
+}
+
+static inline bool btf_is_restrict(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_RESTRICT;
+}
+
+static inline bool btf_is_mod(const struct btf_type *t)
+{
+	__u16 kind = btf_kind(t);
+
+	return kind == BTF_KIND_VOLATILE ||
+	       kind == BTF_KIND_CONST ||
+	       kind == BTF_KIND_RESTRICT ||
+	       kind == BTF_KIND_TYPE_TAG;
+}
+
+static inline bool btf_is_func(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_FUNC;
+}
+
+static inline bool btf_is_func_proto(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_FUNC_PROTO;
+}
+
+static inline bool btf_is_var(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_VAR;
+}
+
+static inline bool btf_is_datasec(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_DATASEC;
+}
+
+static inline bool btf_is_float(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_FLOAT;
+}
+
+static inline bool btf_is_decl_tag(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_DECL_TAG;
+}
+
+static inline bool btf_is_type_tag(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_TYPE_TAG;
+}
+
+static inline bool btf_is_any_enum(const struct btf_type *t)
+{
+	return btf_is_enum(t) || btf_is_enum64(t);
+}
+
+static inline bool btf_kind_core_compat(const struct btf_type *t1,
+					const struct btf_type *t2)
+{
+	return btf_kind(t1) == btf_kind(t2) ||
+	       (btf_is_any_enum(t1) && btf_is_any_enum(t2));
+}
+
+static inline __u8 btf_int_encoding(const struct btf_type *t)
+{
+	return BTF_INT_ENCODING(*(__u32 *)(t + 1));
+}
+
+static inline __u8 btf_int_offset(const struct btf_type *t)
+{
+	return BTF_INT_OFFSET(*(__u32 *)(t + 1));
+}
+
+static inline __u8 btf_int_bits(const struct btf_type *t)
+{
+	return BTF_INT_BITS(*(__u32 *)(t + 1));
+}
+
+static inline struct btf_array *btf_array(const struct btf_type *t)
+{
+	return (struct btf_array *)(t + 1);
+}
+
+static inline struct btf_enum *btf_enum(const struct btf_type *t)
+{
+	return (struct btf_enum *)(t + 1);
+}
+
+struct btf_enum64;
+
+static inline struct btf_enum64 *btf_enum64(const struct btf_type *t)
+{
+	return (struct btf_enum64 *)(t + 1);
+}
+
+static inline __u64 btf_enum64_value(const struct btf_enum64 *e)
+{
+	/* struct btf_enum64 is introduced in Linux 6.0, which is very
+	 * bleeding-edge. Here we are avoiding relying on struct btf_enum64
+	 * definition coming from kernel UAPI headers to support wider range
+	 * of system-wide kernel headers.
+	 *
+	 * Given this header can be also included from C++ applications, that
+	 * further restricts C tricks we can use (like using compatible
+	 * anonymous struct). So just treat struct btf_enum64 as
+	 * a three-element array of u32 and access second (lo32) and third
+	 * (hi32) elements directly.
+	 *
+	 * For reference, here is a struct btf_enum64 definition:
+	 *
+	 * const struct btf_enum64 {
+	 *	__u32	name_off;
+	 *	__u32	val_lo32;
+	 *	__u32	val_hi32;
+	 * };
+	 */
+	const __u32 *e64 = (const __u32 *)e;
+
+	return ((__u64)e64[2] << 32) | e64[1];
+}
+
+static inline struct btf_member *btf_members(const struct btf_type *t)
+{
+	return (struct btf_member *)(t + 1);
+}
+
+/* Get bit offset of a member with specified index. */
+static inline __u32 btf_member_bit_offset(const struct btf_type *t,
+					  __u32 member_idx)
+{
+	const struct btf_member *m = btf_members(t) + member_idx;
+	bool kflag = btf_kflag(t);
+
+	return kflag ? BTF_MEMBER_BIT_OFFSET(m->offset) : m->offset;
+}
+/*
+ * Get bitfield size of a member, assuming t is BTF_KIND_STRUCT or
+ * BTF_KIND_UNION. If member is not a bitfield, zero is returned.
+ */
+static inline __u32 btf_member_bitfield_size(const struct btf_type *t,
+					     __u32 member_idx)
+{
+	const struct btf_member *m = btf_members(t) + member_idx;
+	bool kflag = btf_kflag(t);
+
+	return kflag ? BTF_MEMBER_BITFIELD_SIZE(m->offset) : 0;
+}
+
+static inline struct btf_param *btf_params(const struct btf_type *t)
+{
+	return (struct btf_param *)(t + 1);
+}
+
+static inline struct btf_var *btf_var(const struct btf_type *t)
+{
+	return (struct btf_var *)(t + 1);
+}
+
+static inline struct btf_var_secinfo *
+btf_var_secinfos(const struct btf_type *t)
+{
+	return (struct btf_var_secinfo *)(t + 1);
+}
+
+struct btf_decl_tag;
+static inline struct btf_decl_tag *btf_decl_tag(const struct btf_type *t)
+{
+	return (struct btf_decl_tag *)(t + 1);
+}
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* __LIBBPF_BTF_H */
diff --git a/src/btf_dump.c b/src/btf_dump.c
new file mode 100644
index 0000000..580985e
--- /dev/null
+++ b/src/btf_dump.c
@@ -0,0 +1,2526 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * BTF-to-C type converter.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <endian.h>
+#include <errno.h>
+#include <limits.h>
+#include <linux/err.h>
+#include <linux/btf.h>
+#include <linux/kernel.h>
+#include "btf.h"
+#include "hashmap.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+
+static const char PREFIXES[] = "\t\t\t\t\t\t\t\t\t\t\t\t\t";
+static const size_t PREFIX_CNT = sizeof(PREFIXES) - 1;
+
+static const char *pfx(int lvl)
+{
+	return lvl >= PREFIX_CNT ? PREFIXES : &PREFIXES[PREFIX_CNT - lvl];
+}
+
+enum btf_dump_type_order_state {
+	NOT_ORDERED,
+	ORDERING,
+	ORDERED,
+};
+
+enum btf_dump_type_emit_state {
+	NOT_EMITTED,
+	EMITTING,
+	EMITTED,
+};
+
+/* per-type auxiliary state */
+struct btf_dump_type_aux_state {
+	/* topological sorting state */
+	enum btf_dump_type_order_state order_state: 2;
+	/* emitting state used to determine the need for forward declaration */
+	enum btf_dump_type_emit_state emit_state: 2;
+	/* whether forward declaration was already emitted */
+	__u8 fwd_emitted: 1;
+	/* whether unique non-duplicate name was already assigned */
+	__u8 name_resolved: 1;
+	/* whether type is referenced from any other type */
+	__u8 referenced: 1;
+};
+
+/* indent string length; one indent string is added for each indent level */
+#define BTF_DATA_INDENT_STR_LEN			32
+
+/*
+ * Common internal data for BTF type data dump operations.
+ */
+struct btf_dump_data {
+	const void *data_end;		/* end of valid data to show */
+	bool compact;
+	bool skip_names;
+	bool emit_zeroes;
+	__u8 indent_lvl;	/* base indent level */
+	char indent_str[BTF_DATA_INDENT_STR_LEN];
+	/* below are used during iteration */
+	int depth;
+	bool is_array_member;
+	bool is_array_terminated;
+	bool is_array_char;
+};
+
+struct btf_dump {
+	const struct btf *btf;
+	btf_dump_printf_fn_t printf_fn;
+	void *cb_ctx;
+	int ptr_sz;
+	bool strip_mods;
+	bool skip_anon_defs;
+	int last_id;
+
+	/* per-type auxiliary state */
+	struct btf_dump_type_aux_state *type_states;
+	size_t type_states_cap;
+	/* per-type optional cached unique name, must be freed, if present */
+	const char **cached_names;
+	size_t cached_names_cap;
+
+	/* topo-sorted list of dependent type definitions */
+	__u32 *emit_queue;
+	int emit_queue_cap;
+	int emit_queue_cnt;
+
+	/*
+	 * stack of type declarations (e.g., chain of modifiers, arrays,
+	 * funcs, etc)
+	 */
+	__u32 *decl_stack;
+	int decl_stack_cap;
+	int decl_stack_cnt;
+
+	/* maps struct/union/enum name to a number of name occurrences */
+	struct hashmap *type_names;
+	/*
+	 * maps typedef identifiers and enum value names to a number of such
+	 * name occurrences
+	 */
+	struct hashmap *ident_names;
+	/*
+	 * data for typed display; allocated if needed.
+	 */
+	struct btf_dump_data *typed_dump;
+};
+
+static size_t str_hash_fn(long key, void *ctx)
+{
+	return str_hash((void *)key);
+}
+
+static bool str_equal_fn(long a, long b, void *ctx)
+{
+	return strcmp((void *)a, (void *)b) == 0;
+}
+
+static const char *btf_name_of(const struct btf_dump *d, __u32 name_off)
+{
+	return btf__name_by_offset(d->btf, name_off);
+}
+
+static void btf_dump_printf(const struct btf_dump *d, const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	d->printf_fn(d->cb_ctx, fmt, args);
+	va_end(args);
+}
+
+static int btf_dump_mark_referenced(struct btf_dump *d);
+static int btf_dump_resize(struct btf_dump *d);
+
+struct btf_dump *btf_dump__new(const struct btf *btf,
+			       btf_dump_printf_fn_t printf_fn,
+			       void *ctx,
+			       const struct btf_dump_opts *opts)
+{
+	struct btf_dump *d;
+	int err;
+
+	if (!OPTS_VALID(opts, btf_dump_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	if (!printf_fn)
+		return libbpf_err_ptr(-EINVAL);
+
+	d = calloc(1, sizeof(struct btf_dump));
+	if (!d)
+		return libbpf_err_ptr(-ENOMEM);
+
+	d->btf = btf;
+	d->printf_fn = printf_fn;
+	d->cb_ctx = ctx;
+	d->ptr_sz = btf__pointer_size(btf) ? : sizeof(void *);
+
+	d->type_names = hashmap__new(str_hash_fn, str_equal_fn, NULL);
+	if (IS_ERR(d->type_names)) {
+		err = PTR_ERR(d->type_names);
+		d->type_names = NULL;
+		goto err;
+	}
+	d->ident_names = hashmap__new(str_hash_fn, str_equal_fn, NULL);
+	if (IS_ERR(d->ident_names)) {
+		err = PTR_ERR(d->ident_names);
+		d->ident_names = NULL;
+		goto err;
+	}
+
+	err = btf_dump_resize(d);
+	if (err)
+		goto err;
+
+	return d;
+err:
+	btf_dump__free(d);
+	return libbpf_err_ptr(err);
+}
+
+static int btf_dump_resize(struct btf_dump *d)
+{
+	int err, last_id = btf__type_cnt(d->btf) - 1;
+
+	if (last_id <= d->last_id)
+		return 0;
+
+	if (libbpf_ensure_mem((void **)&d->type_states, &d->type_states_cap,
+			      sizeof(*d->type_states), last_id + 1))
+		return -ENOMEM;
+	if (libbpf_ensure_mem((void **)&d->cached_names, &d->cached_names_cap,
+			      sizeof(*d->cached_names), last_id + 1))
+		return -ENOMEM;
+
+	if (d->last_id == 0) {
+		/* VOID is special */
+		d->type_states[0].order_state = ORDERED;
+		d->type_states[0].emit_state = EMITTED;
+	}
+
+	/* eagerly determine referenced types for anon enums */
+	err = btf_dump_mark_referenced(d);
+	if (err)
+		return err;
+
+	d->last_id = last_id;
+	return 0;
+}
+
+static void btf_dump_free_names(struct hashmap *map)
+{
+	size_t bkt;
+	struct hashmap_entry *cur;
+
+	hashmap__for_each_entry(map, cur, bkt)
+		free((void *)cur->pkey);
+
+	hashmap__free(map);
+}
+
+void btf_dump__free(struct btf_dump *d)
+{
+	int i;
+
+	if (IS_ERR_OR_NULL(d))
+		return;
+
+	free(d->type_states);
+	if (d->cached_names) {
+		/* any set cached name is owned by us and should be freed */
+		for (i = 0; i <= d->last_id; i++) {
+			if (d->cached_names[i])
+				free((void *)d->cached_names[i]);
+		}
+	}
+	free(d->cached_names);
+	free(d->emit_queue);
+	free(d->decl_stack);
+	btf_dump_free_names(d->type_names);
+	btf_dump_free_names(d->ident_names);
+
+	free(d);
+}
+
+static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr);
+static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id);
+
+/*
+ * Dump BTF type in a compilable C syntax, including all the necessary
+ * dependent types, necessary for compilation. If some of the dependent types
+ * were already emitted as part of previous btf_dump__dump_type() invocation
+ * for another type, they won't be emitted again. This API allows callers to
+ * filter out BTF types according to user-defined criterias and emitted only
+ * minimal subset of types, necessary to compile everything. Full struct/union
+ * definitions will still be emitted, even if the only usage is through
+ * pointer and could be satisfied with just a forward declaration.
+ *
+ * Dumping is done in two high-level passes:
+ *   1. Topologically sort type definitions to satisfy C rules of compilation.
+ *   2. Emit type definitions in C syntax.
+ *
+ * Returns 0 on success; <0, otherwise.
+ */
+int btf_dump__dump_type(struct btf_dump *d, __u32 id)
+{
+	int err, i;
+
+	if (id >= btf__type_cnt(d->btf))
+		return libbpf_err(-EINVAL);
+
+	err = btf_dump_resize(d);
+	if (err)
+		return libbpf_err(err);
+
+	d->emit_queue_cnt = 0;
+	err = btf_dump_order_type(d, id, false);
+	if (err < 0)
+		return libbpf_err(err);
+
+	for (i = 0; i < d->emit_queue_cnt; i++)
+		btf_dump_emit_type(d, d->emit_queue[i], 0 /*top-level*/);
+
+	return 0;
+}
+
+/*
+ * Mark all types that are referenced from any other type. This is used to
+ * determine top-level anonymous enums that need to be emitted as an
+ * independent type declarations.
+ * Anonymous enums come in two flavors: either embedded in a struct's field
+ * definition, in which case they have to be declared inline as part of field
+ * type declaration; or as a top-level anonymous enum, typically used for
+ * declaring global constants. It's impossible to distinguish between two
+ * without knowning whether given enum type was referenced from other type:
+ * top-level anonymous enum won't be referenced by anything, while embedded
+ * one will.
+ */
+static int btf_dump_mark_referenced(struct btf_dump *d)
+{
+	int i, j, n = btf__type_cnt(d->btf);
+	const struct btf_type *t;
+	__u16 vlen;
+
+	for (i = d->last_id + 1; i < n; i++) {
+		t = btf__type_by_id(d->btf, i);
+		vlen = btf_vlen(t);
+
+		switch (btf_kind(t)) {
+		case BTF_KIND_INT:
+		case BTF_KIND_ENUM:
+		case BTF_KIND_ENUM64:
+		case BTF_KIND_FWD:
+		case BTF_KIND_FLOAT:
+			break;
+
+		case BTF_KIND_VOLATILE:
+		case BTF_KIND_CONST:
+		case BTF_KIND_RESTRICT:
+		case BTF_KIND_PTR:
+		case BTF_KIND_TYPEDEF:
+		case BTF_KIND_FUNC:
+		case BTF_KIND_VAR:
+		case BTF_KIND_DECL_TAG:
+		case BTF_KIND_TYPE_TAG:
+			d->type_states[t->type].referenced = 1;
+			break;
+
+		case BTF_KIND_ARRAY: {
+			const struct btf_array *a = btf_array(t);
+
+			d->type_states[a->index_type].referenced = 1;
+			d->type_states[a->type].referenced = 1;
+			break;
+		}
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION: {
+			const struct btf_member *m = btf_members(t);
+
+			for (j = 0; j < vlen; j++, m++)
+				d->type_states[m->type].referenced = 1;
+			break;
+		}
+		case BTF_KIND_FUNC_PROTO: {
+			const struct btf_param *p = btf_params(t);
+
+			for (j = 0; j < vlen; j++, p++)
+				d->type_states[p->type].referenced = 1;
+			break;
+		}
+		case BTF_KIND_DATASEC: {
+			const struct btf_var_secinfo *v = btf_var_secinfos(t);
+
+			for (j = 0; j < vlen; j++, v++)
+				d->type_states[v->type].referenced = 1;
+			break;
+		}
+		default:
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+static int btf_dump_add_emit_queue_id(struct btf_dump *d, __u32 id)
+{
+	__u32 *new_queue;
+	size_t new_cap;
+
+	if (d->emit_queue_cnt >= d->emit_queue_cap) {
+		new_cap = max(16, d->emit_queue_cap * 3 / 2);
+		new_queue = libbpf_reallocarray(d->emit_queue, new_cap, sizeof(new_queue[0]));
+		if (!new_queue)
+			return -ENOMEM;
+		d->emit_queue = new_queue;
+		d->emit_queue_cap = new_cap;
+	}
+
+	d->emit_queue[d->emit_queue_cnt++] = id;
+	return 0;
+}
+
+/*
+ * Determine order of emitting dependent types and specified type to satisfy
+ * C compilation rules.  This is done through topological sorting with an
+ * additional complication which comes from C rules. The main idea for C is
+ * that if some type is "embedded" into a struct/union, it's size needs to be
+ * known at the time of definition of containing type. E.g., for:
+ *
+ *	struct A {};
+ *	struct B { struct A x; }
+ *
+ * struct A *HAS* to be defined before struct B, because it's "embedded",
+ * i.e., it is part of struct B layout. But in the following case:
+ *
+ *	struct A;
+ *	struct B { struct A *x; }
+ *	struct A {};
+ *
+ * it's enough to just have a forward declaration of struct A at the time of
+ * struct B definition, as struct B has a pointer to struct A, so the size of
+ * field x is known without knowing struct A size: it's sizeof(void *).
+ *
+ * Unfortunately, there are some trickier cases we need to handle, e.g.:
+ *
+ *	struct A {}; // if this was forward-declaration: compilation error
+ *	struct B {
+ *		struct { // anonymous struct
+ *			struct A y;
+ *		} *x;
+ *	};
+ *
+ * In this case, struct B's field x is a pointer, so it's size is known
+ * regardless of the size of (anonymous) struct it points to. But because this
+ * struct is anonymous and thus defined inline inside struct B, *and* it
+ * embeds struct A, compiler requires full definition of struct A to be known
+ * before struct B can be defined. This creates a transitive dependency
+ * between struct A and struct B. If struct A was forward-declared before
+ * struct B definition and fully defined after struct B definition, that would
+ * trigger compilation error.
+ *
+ * All this means that while we are doing topological sorting on BTF type
+ * graph, we need to determine relationships between different types (graph
+ * nodes):
+ *   - weak link (relationship) between X and Y, if Y *CAN* be
+ *   forward-declared at the point of X definition;
+ *   - strong link, if Y *HAS* to be fully-defined before X can be defined.
+ *
+ * The rule is as follows. Given a chain of BTF types from X to Y, if there is
+ * BTF_KIND_PTR type in the chain and at least one non-anonymous type
+ * Z (excluding X, including Y), then link is weak. Otherwise, it's strong.
+ * Weak/strong relationship is determined recursively during DFS traversal and
+ * is returned as a result from btf_dump_order_type().
+ *
+ * btf_dump_order_type() is trying to avoid unnecessary forward declarations,
+ * but it is not guaranteeing that no extraneous forward declarations will be
+ * emitted.
+ *
+ * To avoid extra work, algorithm marks some of BTF types as ORDERED, when
+ * it's done with them, but not for all (e.g., VOLATILE, CONST, RESTRICT,
+ * ARRAY, FUNC_PROTO), as weak/strong semantics for those depends on the
+ * entire graph path, so depending where from one came to that BTF type, it
+ * might cause weak or strong ordering. For types like STRUCT/UNION/INT/ENUM,
+ * once they are processed, there is no need to do it again, so they are
+ * marked as ORDERED. We can mark PTR as ORDERED as well, as it semi-forces
+ * weak link, unless subsequent referenced STRUCT/UNION/ENUM is anonymous. But
+ * in any case, once those are processed, no need to do it again, as the
+ * result won't change.
+ *
+ * Returns:
+ *   - 1, if type is part of strong link (so there is strong topological
+ *   ordering requirements);
+ *   - 0, if type is part of weak link (so can be satisfied through forward
+ *   declaration);
+ *   - <0, on error (e.g., unsatisfiable type loop detected).
+ */
+static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
+{
+	/*
+	 * Order state is used to detect strong link cycles, but only for BTF
+	 * kinds that are or could be an independent definition (i.e.,
+	 * stand-alone fwd decl, enum, typedef, struct, union). Ptrs, arrays,
+	 * func_protos, modifiers are just means to get to these definitions.
+	 * Int/void don't need definitions, they are assumed to be always
+	 * properly defined.  We also ignore datasec, var, and funcs for now.
+	 * So for all non-defining kinds, we never even set ordering state,
+	 * for defining kinds we set ORDERING and subsequently ORDERED if it
+	 * forms a strong link.
+	 */
+	struct btf_dump_type_aux_state *tstate = &d->type_states[id];
+	const struct btf_type *t;
+	__u16 vlen;
+	int err, i;
+
+	/* return true, letting typedefs know that it's ok to be emitted */
+	if (tstate->order_state == ORDERED)
+		return 1;
+
+	t = btf__type_by_id(d->btf, id);
+
+	if (tstate->order_state == ORDERING) {
+		/* type loop, but resolvable through fwd declaration */
+		if (btf_is_composite(t) && through_ptr && t->name_off != 0)
+			return 0;
+		pr_warn("unsatisfiable type cycle, id:[%u]\n", id);
+		return -ELOOP;
+	}
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_INT:
+	case BTF_KIND_FLOAT:
+		tstate->order_state = ORDERED;
+		return 0;
+
+	case BTF_KIND_PTR:
+		err = btf_dump_order_type(d, t->type, true);
+		tstate->order_state = ORDERED;
+		return err;
+
+	case BTF_KIND_ARRAY:
+		return btf_dump_order_type(d, btf_array(t)->type, false);
+
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		const struct btf_member *m = btf_members(t);
+		/*
+		 * struct/union is part of strong link, only if it's embedded
+		 * (so no ptr in a path) or it's anonymous (so has to be
+		 * defined inline, even if declared through ptr)
+		 */
+		if (through_ptr && t->name_off != 0)
+			return 0;
+
+		tstate->order_state = ORDERING;
+
+		vlen = btf_vlen(t);
+		for (i = 0; i < vlen; i++, m++) {
+			err = btf_dump_order_type(d, m->type, false);
+			if (err < 0)
+				return err;
+		}
+
+		if (t->name_off != 0) {
+			err = btf_dump_add_emit_queue_id(d, id);
+			if (err < 0)
+				return err;
+		}
+
+		tstate->order_state = ORDERED;
+		return 1;
+	}
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+	case BTF_KIND_FWD:
+		/*
+		 * non-anonymous or non-referenced enums are top-level
+		 * declarations and should be emitted. Same logic can be
+		 * applied to FWDs, it won't hurt anyways.
+		 */
+		if (t->name_off != 0 || !tstate->referenced) {
+			err = btf_dump_add_emit_queue_id(d, id);
+			if (err)
+				return err;
+		}
+		tstate->order_state = ORDERED;
+		return 1;
+
+	case BTF_KIND_TYPEDEF: {
+		int is_strong;
+
+		is_strong = btf_dump_order_type(d, t->type, through_ptr);
+		if (is_strong < 0)
+			return is_strong;
+
+		/* typedef is similar to struct/union w.r.t. fwd-decls */
+		if (through_ptr && !is_strong)
+			return 0;
+
+		/* typedef is always a named definition */
+		err = btf_dump_add_emit_queue_id(d, id);
+		if (err)
+			return err;
+
+		d->type_states[id].order_state = ORDERED;
+		return 1;
+	}
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_CONST:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_TYPE_TAG:
+		return btf_dump_order_type(d, t->type, through_ptr);
+
+	case BTF_KIND_FUNC_PROTO: {
+		const struct btf_param *p = btf_params(t);
+		bool is_strong;
+
+		err = btf_dump_order_type(d, t->type, through_ptr);
+		if (err < 0)
+			return err;
+		is_strong = err > 0;
+
+		vlen = btf_vlen(t);
+		for (i = 0; i < vlen; i++, p++) {
+			err = btf_dump_order_type(d, p->type, through_ptr);
+			if (err < 0)
+				return err;
+			if (err > 0)
+				is_strong = true;
+		}
+		return is_strong;
+	}
+	case BTF_KIND_FUNC:
+	case BTF_KIND_VAR:
+	case BTF_KIND_DATASEC:
+	case BTF_KIND_DECL_TAG:
+		d->type_states[id].order_state = ORDERED;
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id,
+					  const struct btf_type *t);
+
+static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id,
+				     const struct btf_type *t);
+static void btf_dump_emit_struct_def(struct btf_dump *d, __u32 id,
+				     const struct btf_type *t, int lvl);
+
+static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id,
+				   const struct btf_type *t);
+static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id,
+				   const struct btf_type *t, int lvl);
+
+static void btf_dump_emit_fwd_def(struct btf_dump *d, __u32 id,
+				  const struct btf_type *t);
+
+static void btf_dump_emit_typedef_def(struct btf_dump *d, __u32 id,
+				      const struct btf_type *t, int lvl);
+
+/* a local view into a shared stack */
+struct id_stack {
+	const __u32 *ids;
+	int cnt;
+};
+
+static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
+				    const char *fname, int lvl);
+static void btf_dump_emit_type_chain(struct btf_dump *d,
+				     struct id_stack *decl_stack,
+				     const char *fname, int lvl);
+
+static const char *btf_dump_type_name(struct btf_dump *d, __u32 id);
+static const char *btf_dump_ident_name(struct btf_dump *d, __u32 id);
+static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_map,
+				 const char *orig_name);
+
+static bool btf_dump_is_blacklisted(struct btf_dump *d, __u32 id)
+{
+	const struct btf_type *t = btf__type_by_id(d->btf, id);
+
+	/* __builtin_va_list is a compiler built-in, which causes compilation
+	 * errors, when compiling w/ different compiler, then used to compile
+	 * original code (e.g., GCC to compile kernel, Clang to use generated
+	 * C header from BTF). As it is built-in, it should be already defined
+	 * properly internally in compiler.
+	 */
+	if (t->name_off == 0)
+		return false;
+	return strcmp(btf_name_of(d, t->name_off), "__builtin_va_list") == 0;
+}
+
+/*
+ * Emit C-syntax definitions of types from chains of BTF types.
+ *
+ * High-level handling of determining necessary forward declarations are handled
+ * by btf_dump_emit_type() itself, but all nitty-gritty details of emitting type
+ * declarations/definitions in C syntax  are handled by a combo of
+ * btf_dump_emit_type_decl()/btf_dump_emit_type_chain() w/ delegation to
+ * corresponding btf_dump_emit_*_{def,fwd}() functions.
+ *
+ * We also keep track of "containing struct/union type ID" to determine when
+ * we reference it from inside and thus can avoid emitting unnecessary forward
+ * declaration.
+ *
+ * This algorithm is designed in such a way, that even if some error occurs
+ * (either technical, e.g., out of memory, or logical, i.e., malformed BTF
+ * that doesn't comply to C rules completely), algorithm will try to proceed
+ * and produce as much meaningful output as possible.
+ */
+static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id)
+{
+	struct btf_dump_type_aux_state *tstate = &d->type_states[id];
+	bool top_level_def = cont_id == 0;
+	const struct btf_type *t;
+	__u16 kind;
+
+	if (tstate->emit_state == EMITTED)
+		return;
+
+	t = btf__type_by_id(d->btf, id);
+	kind = btf_kind(t);
+
+	if (tstate->emit_state == EMITTING) {
+		if (tstate->fwd_emitted)
+			return;
+
+		switch (kind) {
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION:
+			/*
+			 * if we are referencing a struct/union that we are
+			 * part of - then no need for fwd declaration
+			 */
+			if (id == cont_id)
+				return;
+			if (t->name_off == 0) {
+				pr_warn("anonymous struct/union loop, id:[%u]\n",
+					id);
+				return;
+			}
+			btf_dump_emit_struct_fwd(d, id, t);
+			btf_dump_printf(d, ";\n\n");
+			tstate->fwd_emitted = 1;
+			break;
+		case BTF_KIND_TYPEDEF:
+			/*
+			 * for typedef fwd_emitted means typedef definition
+			 * was emitted, but it can be used only for "weak"
+			 * references through pointer only, not for embedding
+			 */
+			if (!btf_dump_is_blacklisted(d, id)) {
+				btf_dump_emit_typedef_def(d, id, t, 0);
+				btf_dump_printf(d, ";\n\n");
+			}
+			tstate->fwd_emitted = 1;
+			break;
+		default:
+			break;
+		}
+
+		return;
+	}
+
+	switch (kind) {
+	case BTF_KIND_INT:
+		/* Emit type alias definitions if necessary */
+		btf_dump_emit_missing_aliases(d, id, t);
+
+		tstate->emit_state = EMITTED;
+		break;
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		if (top_level_def) {
+			btf_dump_emit_enum_def(d, id, t, 0);
+			btf_dump_printf(d, ";\n\n");
+		}
+		tstate->emit_state = EMITTED;
+		break;
+	case BTF_KIND_PTR:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_CONST:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_TYPE_TAG:
+		btf_dump_emit_type(d, t->type, cont_id);
+		break;
+	case BTF_KIND_ARRAY:
+		btf_dump_emit_type(d, btf_array(t)->type, cont_id);
+		break;
+	case BTF_KIND_FWD:
+		btf_dump_emit_fwd_def(d, id, t);
+		btf_dump_printf(d, ";\n\n");
+		tstate->emit_state = EMITTED;
+		break;
+	case BTF_KIND_TYPEDEF:
+		tstate->emit_state = EMITTING;
+		btf_dump_emit_type(d, t->type, id);
+		/*
+		 * typedef can server as both definition and forward
+		 * declaration; at this stage someone depends on
+		 * typedef as a forward declaration (refers to it
+		 * through pointer), so unless we already did it,
+		 * emit typedef as a forward declaration
+		 */
+		if (!tstate->fwd_emitted && !btf_dump_is_blacklisted(d, id)) {
+			btf_dump_emit_typedef_def(d, id, t, 0);
+			btf_dump_printf(d, ";\n\n");
+		}
+		tstate->emit_state = EMITTED;
+		break;
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+		tstate->emit_state = EMITTING;
+		/* if it's a top-level struct/union definition or struct/union
+		 * is anonymous, then in C we'll be emitting all fields and
+		 * their types (as opposed to just `struct X`), so we need to
+		 * make sure that all types, referenced from struct/union
+		 * members have necessary forward-declarations, where
+		 * applicable
+		 */
+		if (top_level_def || t->name_off == 0) {
+			const struct btf_member *m = btf_members(t);
+			__u16 vlen = btf_vlen(t);
+			int i, new_cont_id;
+
+			new_cont_id = t->name_off == 0 ? cont_id : id;
+			for (i = 0; i < vlen; i++, m++)
+				btf_dump_emit_type(d, m->type, new_cont_id);
+		} else if (!tstate->fwd_emitted && id != cont_id) {
+			btf_dump_emit_struct_fwd(d, id, t);
+			btf_dump_printf(d, ";\n\n");
+			tstate->fwd_emitted = 1;
+		}
+
+		if (top_level_def) {
+			btf_dump_emit_struct_def(d, id, t, 0);
+			btf_dump_printf(d, ";\n\n");
+			tstate->emit_state = EMITTED;
+		} else {
+			tstate->emit_state = NOT_EMITTED;
+		}
+		break;
+	case BTF_KIND_FUNC_PROTO: {
+		const struct btf_param *p = btf_params(t);
+		__u16 n = btf_vlen(t);
+		int i;
+
+		btf_dump_emit_type(d, t->type, cont_id);
+		for (i = 0; i < n; i++, p++)
+			btf_dump_emit_type(d, p->type, cont_id);
+
+		break;
+	}
+	default:
+		break;
+	}
+}
+
+static bool btf_is_struct_packed(const struct btf *btf, __u32 id,
+				 const struct btf_type *t)
+{
+	const struct btf_member *m;
+	int max_align = 1, align, i, bit_sz;
+	__u16 vlen;
+
+	m = btf_members(t);
+	vlen = btf_vlen(t);
+	/* all non-bitfield fields have to be naturally aligned */
+	for (i = 0; i < vlen; i++, m++) {
+		align = btf__align_of(btf, m->type);
+		bit_sz = btf_member_bitfield_size(t, i);
+		if (align && bit_sz == 0 && m->offset % (8 * align) != 0)
+			return true;
+		max_align = max(align, max_align);
+	}
+	/* size of a non-packed struct has to be a multiple of its alignment */
+	if (t->size % max_align != 0)
+		return true;
+	/*
+	 * if original struct was marked as packed, but its layout is
+	 * naturally aligned, we'll detect that it's not packed
+	 */
+	return false;
+}
+
+static void btf_dump_emit_bit_padding(const struct btf_dump *d,
+				      int cur_off, int next_off, int next_align,
+				      bool in_bitfield, int lvl)
+{
+	const struct {
+		const char *name;
+		int bits;
+	} pads[] = {
+		{"long", d->ptr_sz * 8}, {"int", 32}, {"short", 16}, {"char", 8}
+	};
+	int new_off, pad_bits, bits, i;
+	const char *pad_type;
+
+	if (cur_off >= next_off)
+		return; /* no gap */
+
+	/* For filling out padding we want to take advantage of
+	 * natural alignment rules to minimize unnecessary explicit
+	 * padding. First, we find the largest type (among long, int,
+	 * short, or char) that can be used to force naturally aligned
+	 * boundary. Once determined, we'll use such type to fill in
+	 * the remaining padding gap. In some cases we can rely on
+	 * compiler filling some gaps, but sometimes we need to force
+	 * alignment to close natural alignment with markers like
+	 * `long: 0` (this is always the case for bitfields).  Note
+	 * that even if struct itself has, let's say 4-byte alignment
+	 * (i.e., it only uses up to int-aligned types), using `long:
+	 * X;` explicit padding doesn't actually change struct's
+	 * overall alignment requirements, but compiler does take into
+	 * account that type's (long, in this example) natural
+	 * alignment requirements when adding implicit padding. We use
+	 * this fact heavily and don't worry about ruining correct
+	 * struct alignment requirement.
+	 */
+	for (i = 0; i < ARRAY_SIZE(pads); i++) {
+		pad_bits = pads[i].bits;
+		pad_type = pads[i].name;
+
+		new_off = roundup(cur_off, pad_bits);
+		if (new_off <= next_off)
+			break;
+	}
+
+	if (new_off > cur_off && new_off <= next_off) {
+		/* We need explicit `<type>: 0` aligning mark if next
+		 * field is right on alignment offset and its
+		 * alignment requirement is less strict than <type>'s
+		 * alignment (so compiler won't naturally align to the
+		 * offset we expect), or if subsequent `<type>: X`,
+		 * will actually completely fit in the remaining hole,
+		 * making compiler basically ignore `<type>: X`
+		 * completely.
+		 */
+		if (in_bitfield ||
+		    (new_off == next_off && roundup(cur_off, next_align * 8) != new_off) ||
+		    (new_off != next_off && next_off - new_off <= new_off - cur_off))
+			/* but for bitfields we'll emit explicit bit count */
+			btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type,
+					in_bitfield ? new_off - cur_off : 0);
+		cur_off = new_off;
+	}
+
+	/* Now we know we start at naturally aligned offset for a chosen
+	 * padding type (long, int, short, or char), and so the rest is just
+	 * a straightforward filling of remaining padding gap with full
+	 * `<type>: sizeof(<type>);` markers, except for the last one, which
+	 * might need smaller than sizeof(<type>) padding.
+	 */
+	while (cur_off != next_off) {
+		bits = min(next_off - cur_off, pad_bits);
+		if (bits == pad_bits) {
+			btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type, pad_bits);
+			cur_off += bits;
+			continue;
+		}
+		/* For the remainder padding that doesn't cover entire
+		 * pad_type bit length, we pick the smallest necessary type.
+		 * This is pure aesthetics, we could have just used `long`,
+		 * but having smallest necessary one communicates better the
+		 * scale of the padding gap.
+		 */
+		for (i = ARRAY_SIZE(pads) - 1; i >= 0; i--) {
+			pad_type = pads[i].name;
+			pad_bits = pads[i].bits;
+			if (pad_bits < bits)
+				continue;
+
+			btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type, bits);
+			cur_off += bits;
+			break;
+		}
+	}
+}
+
+static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id,
+				     const struct btf_type *t)
+{
+	btf_dump_printf(d, "%s%s%s",
+			btf_is_struct(t) ? "struct" : "union",
+			t->name_off ? " " : "",
+			btf_dump_type_name(d, id));
+}
+
+static void btf_dump_emit_struct_def(struct btf_dump *d,
+				     __u32 id,
+				     const struct btf_type *t,
+				     int lvl)
+{
+	const struct btf_member *m = btf_members(t);
+	bool is_struct = btf_is_struct(t);
+	bool packed, prev_bitfield = false;
+	int align, i, off = 0;
+	__u16 vlen = btf_vlen(t);
+
+	align = btf__align_of(d->btf, id);
+	packed = is_struct ? btf_is_struct_packed(d->btf, id, t) : 0;
+
+	btf_dump_printf(d, "%s%s%s {",
+			is_struct ? "struct" : "union",
+			t->name_off ? " " : "",
+			btf_dump_type_name(d, id));
+
+	for (i = 0; i < vlen; i++, m++) {
+		const char *fname;
+		int m_off, m_sz, m_align;
+		bool in_bitfield;
+
+		fname = btf_name_of(d, m->name_off);
+		m_sz = btf_member_bitfield_size(t, i);
+		m_off = btf_member_bit_offset(t, i);
+		m_align = packed ? 1 : btf__align_of(d->btf, m->type);
+
+		in_bitfield = prev_bitfield && m_sz != 0;
+
+		btf_dump_emit_bit_padding(d, off, m_off, m_align, in_bitfield, lvl + 1);
+		btf_dump_printf(d, "\n%s", pfx(lvl + 1));
+		btf_dump_emit_type_decl(d, m->type, fname, lvl + 1);
+
+		if (m_sz) {
+			btf_dump_printf(d, ": %d", m_sz);
+			off = m_off + m_sz;
+			prev_bitfield = true;
+		} else {
+			m_sz = max((__s64)0, btf__resolve_size(d->btf, m->type));
+			off = m_off + m_sz * 8;
+			prev_bitfield = false;
+		}
+
+		btf_dump_printf(d, ";");
+	}
+
+	/* pad at the end, if necessary */
+	if (is_struct)
+		btf_dump_emit_bit_padding(d, off, t->size * 8, align, false, lvl + 1);
+
+	/*
+	 * Keep `struct empty {}` on a single line,
+	 * only print newline when there are regular or padding fields.
+	 */
+	if (vlen || t->size) {
+		btf_dump_printf(d, "\n");
+		btf_dump_printf(d, "%s}", pfx(lvl));
+	} else {
+		btf_dump_printf(d, "}");
+	}
+	if (packed)
+		btf_dump_printf(d, " __attribute__((packed))");
+}
+
+static const char *missing_base_types[][2] = {
+	/*
+	 * GCC emits typedefs to its internal __PolyX_t types when compiling Arm
+	 * SIMD intrinsics. Alias them to standard base types.
+	 */
+	{ "__Poly8_t",		"unsigned char" },
+	{ "__Poly16_t",		"unsigned short" },
+	{ "__Poly64_t",		"unsigned long long" },
+	{ "__Poly128_t",	"unsigned __int128" },
+};
+
+static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id,
+					  const struct btf_type *t)
+{
+	const char *name = btf_dump_type_name(d, id);
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(missing_base_types); i++) {
+		if (strcmp(name, missing_base_types[i][0]) == 0) {
+			btf_dump_printf(d, "typedef %s %s;\n\n",
+					missing_base_types[i][1], name);
+			break;
+		}
+	}
+}
+
+static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id,
+				   const struct btf_type *t)
+{
+	btf_dump_printf(d, "enum %s", btf_dump_type_name(d, id));
+}
+
+static void btf_dump_emit_enum32_val(struct btf_dump *d,
+				     const struct btf_type *t,
+				     int lvl, __u16 vlen)
+{
+	const struct btf_enum *v = btf_enum(t);
+	bool is_signed = btf_kflag(t);
+	const char *fmt_str;
+	const char *name;
+	size_t dup_cnt;
+	int i;
+
+	for (i = 0; i < vlen; i++, v++) {
+		name = btf_name_of(d, v->name_off);
+		/* enumerators share namespace with typedef idents */
+		dup_cnt = btf_dump_name_dups(d, d->ident_names, name);
+		if (dup_cnt > 1) {
+			fmt_str = is_signed ? "\n%s%s___%zd = %d," : "\n%s%s___%zd = %u,";
+			btf_dump_printf(d, fmt_str, pfx(lvl + 1), name, dup_cnt, v->val);
+		} else {
+			fmt_str = is_signed ? "\n%s%s = %d," : "\n%s%s = %u,";
+			btf_dump_printf(d, fmt_str, pfx(lvl + 1), name, v->val);
+		}
+	}
+}
+
+static void btf_dump_emit_enum64_val(struct btf_dump *d,
+				     const struct btf_type *t,
+				     int lvl, __u16 vlen)
+{
+	const struct btf_enum64 *v = btf_enum64(t);
+	bool is_signed = btf_kflag(t);
+	const char *fmt_str;
+	const char *name;
+	size_t dup_cnt;
+	__u64 val;
+	int i;
+
+	for (i = 0; i < vlen; i++, v++) {
+		name = btf_name_of(d, v->name_off);
+		dup_cnt = btf_dump_name_dups(d, d->ident_names, name);
+		val = btf_enum64_value(v);
+		if (dup_cnt > 1) {
+			fmt_str = is_signed ? "\n%s%s___%zd = %lldLL,"
+					    : "\n%s%s___%zd = %lluULL,";
+			btf_dump_printf(d, fmt_str,
+					pfx(lvl + 1), name, dup_cnt,
+					(unsigned long long)val);
+		} else {
+			fmt_str = is_signed ? "\n%s%s = %lldLL,"
+					    : "\n%s%s = %lluULL,";
+			btf_dump_printf(d, fmt_str,
+					pfx(lvl + 1), name,
+					(unsigned long long)val);
+		}
+	}
+}
+static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id,
+				   const struct btf_type *t,
+				   int lvl)
+{
+	__u16 vlen = btf_vlen(t);
+
+	btf_dump_printf(d, "enum%s%s",
+			t->name_off ? " " : "",
+			btf_dump_type_name(d, id));
+
+	if (!vlen)
+		return;
+
+	btf_dump_printf(d, " {");
+	if (btf_is_enum(t))
+		btf_dump_emit_enum32_val(d, t, lvl, vlen);
+	else
+		btf_dump_emit_enum64_val(d, t, lvl, vlen);
+	btf_dump_printf(d, "\n%s}", pfx(lvl));
+
+	/* special case enums with special sizes */
+	if (t->size == 1) {
+		/* one-byte enums can be forced with mode(byte) attribute */
+		btf_dump_printf(d, " __attribute__((mode(byte)))");
+	} else if (t->size == 8 && d->ptr_sz == 8) {
+		/* enum can be 8-byte sized if one of the enumerator values
+		 * doesn't fit in 32-bit integer, or by adding mode(word)
+		 * attribute (but probably only on 64-bit architectures); do
+		 * our best here to try to satisfy the contract without adding
+		 * unnecessary attributes
+		 */
+		bool needs_word_mode;
+
+		if (btf_is_enum(t)) {
+			/* enum can't represent 64-bit values, so we need word mode */
+			needs_word_mode = true;
+		} else {
+			/* enum64 needs mode(word) if none of its values has
+			 * non-zero upper 32-bits (which means that all values
+			 * fit in 32-bit integers and won't cause compiler to
+			 * bump enum to be 64-bit naturally
+			 */
+			int i;
+
+			needs_word_mode = true;
+			for (i = 0; i < vlen; i++) {
+				if (btf_enum64(t)[i].val_hi32 != 0) {
+					needs_word_mode = false;
+					break;
+				}
+			}
+		}
+		if (needs_word_mode)
+			btf_dump_printf(d, " __attribute__((mode(word)))");
+	}
+
+}
+
+static void btf_dump_emit_fwd_def(struct btf_dump *d, __u32 id,
+				  const struct btf_type *t)
+{
+	const char *name = btf_dump_type_name(d, id);
+
+	if (btf_kflag(t))
+		btf_dump_printf(d, "union %s", name);
+	else
+		btf_dump_printf(d, "struct %s", name);
+}
+
+static void btf_dump_emit_typedef_def(struct btf_dump *d, __u32 id,
+				     const struct btf_type *t, int lvl)
+{
+	const char *name = btf_dump_ident_name(d, id);
+
+	/*
+	 * Old GCC versions are emitting invalid typedef for __gnuc_va_list
+	 * pointing to VOID. This generates warnings from btf_dump() and
+	 * results in uncompilable header file, so we are fixing it up here
+	 * with valid typedef into __builtin_va_list.
+	 */
+	if (t->type == 0 && strcmp(name, "__gnuc_va_list") == 0) {
+		btf_dump_printf(d, "typedef __builtin_va_list __gnuc_va_list");
+		return;
+	}
+
+	btf_dump_printf(d, "typedef ");
+	btf_dump_emit_type_decl(d, t->type, name, lvl);
+}
+
+static int btf_dump_push_decl_stack_id(struct btf_dump *d, __u32 id)
+{
+	__u32 *new_stack;
+	size_t new_cap;
+
+	if (d->decl_stack_cnt >= d->decl_stack_cap) {
+		new_cap = max(16, d->decl_stack_cap * 3 / 2);
+		new_stack = libbpf_reallocarray(d->decl_stack, new_cap, sizeof(new_stack[0]));
+		if (!new_stack)
+			return -ENOMEM;
+		d->decl_stack = new_stack;
+		d->decl_stack_cap = new_cap;
+	}
+
+	d->decl_stack[d->decl_stack_cnt++] = id;
+
+	return 0;
+}
+
+/*
+ * Emit type declaration (e.g., field type declaration in a struct or argument
+ * declaration in function prototype) in correct C syntax.
+ *
+ * For most types it's trivial, but there are few quirky type declaration
+ * cases worth mentioning:
+ *   - function prototypes (especially nesting of function prototypes);
+ *   - arrays;
+ *   - const/volatile/restrict for pointers vs other types.
+ *
+ * For a good discussion of *PARSING* C syntax (as a human), see
+ * Peter van der Linden's "Expert C Programming: Deep C Secrets",
+ * Ch.3 "Unscrambling Declarations in C".
+ *
+ * It won't help with BTF to C conversion much, though, as it's an opposite
+ * problem. So we came up with this algorithm in reverse to van der Linden's
+ * parsing algorithm. It goes from structured BTF representation of type
+ * declaration to a valid compilable C syntax.
+ *
+ * For instance, consider this C typedef:
+ *	typedef const int * const * arr[10] arr_t;
+ * It will be represented in BTF with this chain of BTF types:
+ *	[typedef] -> [array] -> [ptr] -> [const] -> [ptr] -> [const] -> [int]
+ *
+ * Notice how [const] modifier always goes before type it modifies in BTF type
+ * graph, but in C syntax, const/volatile/restrict modifiers are written to
+ * the right of pointers, but to the left of other types. There are also other
+ * quirks, like function pointers, arrays of them, functions returning other
+ * functions, etc.
+ *
+ * We handle that by pushing all the types to a stack, until we hit "terminal"
+ * type (int/enum/struct/union/fwd). Then depending on the kind of a type on
+ * top of a stack, modifiers are handled differently. Array/function pointers
+ * have also wildly different syntax and how nesting of them are done. See
+ * code for authoritative definition.
+ *
+ * To avoid allocating new stack for each independent chain of BTF types, we
+ * share one bigger stack, with each chain working only on its own local view
+ * of a stack frame. Some care is required to "pop" stack frames after
+ * processing type declaration chain.
+ */
+int btf_dump__emit_type_decl(struct btf_dump *d, __u32 id,
+			     const struct btf_dump_emit_type_decl_opts *opts)
+{
+	const char *fname;
+	int lvl, err;
+
+	if (!OPTS_VALID(opts, btf_dump_emit_type_decl_opts))
+		return libbpf_err(-EINVAL);
+
+	err = btf_dump_resize(d);
+	if (err)
+		return libbpf_err(err);
+
+	fname = OPTS_GET(opts, field_name, "");
+	lvl = OPTS_GET(opts, indent_level, 0);
+	d->strip_mods = OPTS_GET(opts, strip_mods, false);
+	btf_dump_emit_type_decl(d, id, fname, lvl);
+	d->strip_mods = false;
+	return 0;
+}
+
+static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
+				    const char *fname, int lvl)
+{
+	struct id_stack decl_stack;
+	const struct btf_type *t;
+	int err, stack_start;
+
+	stack_start = d->decl_stack_cnt;
+	for (;;) {
+		t = btf__type_by_id(d->btf, id);
+		if (d->strip_mods && btf_is_mod(t))
+			goto skip_mod;
+
+		err = btf_dump_push_decl_stack_id(d, id);
+		if (err < 0) {
+			/*
+			 * if we don't have enough memory for entire type decl
+			 * chain, restore stack, emit warning, and try to
+			 * proceed nevertheless
+			 */
+			pr_warn("not enough memory for decl stack:%d", err);
+			d->decl_stack_cnt = stack_start;
+			return;
+		}
+skip_mod:
+		/* VOID */
+		if (id == 0)
+			break;
+
+		switch (btf_kind(t)) {
+		case BTF_KIND_PTR:
+		case BTF_KIND_VOLATILE:
+		case BTF_KIND_CONST:
+		case BTF_KIND_RESTRICT:
+		case BTF_KIND_FUNC_PROTO:
+		case BTF_KIND_TYPE_TAG:
+			id = t->type;
+			break;
+		case BTF_KIND_ARRAY:
+			id = btf_array(t)->type;
+			break;
+		case BTF_KIND_INT:
+		case BTF_KIND_ENUM:
+		case BTF_KIND_ENUM64:
+		case BTF_KIND_FWD:
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION:
+		case BTF_KIND_TYPEDEF:
+		case BTF_KIND_FLOAT:
+			goto done;
+		default:
+			pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
+				btf_kind(t), id);
+			goto done;
+		}
+	}
+done:
+	/*
+	 * We might be inside a chain of declarations (e.g., array of function
+	 * pointers returning anonymous (so inlined) structs, having another
+	 * array field). Each of those needs its own "stack frame" to handle
+	 * emitting of declarations. Those stack frames are non-overlapping
+	 * portions of shared btf_dump->decl_stack. To make it a bit nicer to
+	 * handle this set of nested stacks, we create a view corresponding to
+	 * our own "stack frame" and work with it as an independent stack.
+	 * We'll need to clean up after emit_type_chain() returns, though.
+	 */
+	decl_stack.ids = d->decl_stack + stack_start;
+	decl_stack.cnt = d->decl_stack_cnt - stack_start;
+	btf_dump_emit_type_chain(d, &decl_stack, fname, lvl);
+	/*
+	 * emit_type_chain() guarantees that it will pop its entire decl_stack
+	 * frame before returning. But it works with a read-only view into
+	 * decl_stack, so it doesn't actually pop anything from the
+	 * perspective of shared btf_dump->decl_stack, per se. We need to
+	 * reset decl_stack state to how it was before us to avoid it growing
+	 * all the time.
+	 */
+	d->decl_stack_cnt = stack_start;
+}
+
+static void btf_dump_emit_mods(struct btf_dump *d, struct id_stack *decl_stack)
+{
+	const struct btf_type *t;
+	__u32 id;
+
+	while (decl_stack->cnt) {
+		id = decl_stack->ids[decl_stack->cnt - 1];
+		t = btf__type_by_id(d->btf, id);
+
+		switch (btf_kind(t)) {
+		case BTF_KIND_VOLATILE:
+			btf_dump_printf(d, "volatile ");
+			break;
+		case BTF_KIND_CONST:
+			btf_dump_printf(d, "const ");
+			break;
+		case BTF_KIND_RESTRICT:
+			btf_dump_printf(d, "restrict ");
+			break;
+		default:
+			return;
+		}
+		decl_stack->cnt--;
+	}
+}
+
+static void btf_dump_drop_mods(struct btf_dump *d, struct id_stack *decl_stack)
+{
+	const struct btf_type *t;
+	__u32 id;
+
+	while (decl_stack->cnt) {
+		id = decl_stack->ids[decl_stack->cnt - 1];
+		t = btf__type_by_id(d->btf, id);
+		if (!btf_is_mod(t))
+			return;
+		decl_stack->cnt--;
+	}
+}
+
+static void btf_dump_emit_name(const struct btf_dump *d,
+			       const char *name, bool last_was_ptr)
+{
+	bool separate = name[0] && !last_was_ptr;
+
+	btf_dump_printf(d, "%s%s", separate ? " " : "", name);
+}
+
+static void btf_dump_emit_type_chain(struct btf_dump *d,
+				     struct id_stack *decls,
+				     const char *fname, int lvl)
+{
+	/*
+	 * last_was_ptr is used to determine if we need to separate pointer
+	 * asterisk (*) from previous part of type signature with space, so
+	 * that we get `int ***`, instead of `int * * *`. We default to true
+	 * for cases where we have single pointer in a chain. E.g., in ptr ->
+	 * func_proto case. func_proto will start a new emit_type_chain call
+	 * with just ptr, which should be emitted as (*) or (*<fname>), so we
+	 * don't want to prepend space for that last pointer.
+	 */
+	bool last_was_ptr = true;
+	const struct btf_type *t;
+	const char *name;
+	__u16 kind;
+	__u32 id;
+
+	while (decls->cnt) {
+		id = decls->ids[--decls->cnt];
+		if (id == 0) {
+			/* VOID is a special snowflake */
+			btf_dump_emit_mods(d, decls);
+			btf_dump_printf(d, "void");
+			last_was_ptr = false;
+			continue;
+		}
+
+		t = btf__type_by_id(d->btf, id);
+		kind = btf_kind(t);
+
+		switch (kind) {
+		case BTF_KIND_INT:
+		case BTF_KIND_FLOAT:
+			btf_dump_emit_mods(d, decls);
+			name = btf_name_of(d, t->name_off);
+			btf_dump_printf(d, "%s", name);
+			break;
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION:
+			btf_dump_emit_mods(d, decls);
+			/* inline anonymous struct/union */
+			if (t->name_off == 0 && !d->skip_anon_defs)
+				btf_dump_emit_struct_def(d, id, t, lvl);
+			else
+				btf_dump_emit_struct_fwd(d, id, t);
+			break;
+		case BTF_KIND_ENUM:
+		case BTF_KIND_ENUM64:
+			btf_dump_emit_mods(d, decls);
+			/* inline anonymous enum */
+			if (t->name_off == 0 && !d->skip_anon_defs)
+				btf_dump_emit_enum_def(d, id, t, lvl);
+			else
+				btf_dump_emit_enum_fwd(d, id, t);
+			break;
+		case BTF_KIND_FWD:
+			btf_dump_emit_mods(d, decls);
+			btf_dump_emit_fwd_def(d, id, t);
+			break;
+		case BTF_KIND_TYPEDEF:
+			btf_dump_emit_mods(d, decls);
+			btf_dump_printf(d, "%s", btf_dump_ident_name(d, id));
+			break;
+		case BTF_KIND_PTR:
+			btf_dump_printf(d, "%s", last_was_ptr ? "*" : " *");
+			break;
+		case BTF_KIND_VOLATILE:
+			btf_dump_printf(d, " volatile");
+			break;
+		case BTF_KIND_CONST:
+			btf_dump_printf(d, " const");
+			break;
+		case BTF_KIND_RESTRICT:
+			btf_dump_printf(d, " restrict");
+			break;
+		case BTF_KIND_TYPE_TAG:
+			btf_dump_emit_mods(d, decls);
+			name = btf_name_of(d, t->name_off);
+			btf_dump_printf(d, " __attribute__((btf_type_tag(\"%s\")))", name);
+			break;
+		case BTF_KIND_ARRAY: {
+			const struct btf_array *a = btf_array(t);
+			const struct btf_type *next_t;
+			__u32 next_id;
+			bool multidim;
+			/*
+			 * GCC has a bug
+			 * (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=8354)
+			 * which causes it to emit extra const/volatile
+			 * modifiers for an array, if array's element type has
+			 * const/volatile modifiers. Clang doesn't do that.
+			 * In general, it doesn't seem very meaningful to have
+			 * a const/volatile modifier for array, so we are
+			 * going to silently skip them here.
+			 */
+			btf_dump_drop_mods(d, decls);
+
+			if (decls->cnt == 0) {
+				btf_dump_emit_name(d, fname, last_was_ptr);
+				btf_dump_printf(d, "[%u]", a->nelems);
+				return;
+			}
+
+			next_id = decls->ids[decls->cnt - 1];
+			next_t = btf__type_by_id(d->btf, next_id);
+			multidim = btf_is_array(next_t);
+			/* we need space if we have named non-pointer */
+			if (fname[0] && !last_was_ptr)
+				btf_dump_printf(d, " ");
+			/* no parentheses for multi-dimensional array */
+			if (!multidim)
+				btf_dump_printf(d, "(");
+			btf_dump_emit_type_chain(d, decls, fname, lvl);
+			if (!multidim)
+				btf_dump_printf(d, ")");
+			btf_dump_printf(d, "[%u]", a->nelems);
+			return;
+		}
+		case BTF_KIND_FUNC_PROTO: {
+			const struct btf_param *p = btf_params(t);
+			__u16 vlen = btf_vlen(t);
+			int i;
+
+			/*
+			 * GCC emits extra volatile qualifier for
+			 * __attribute__((noreturn)) function pointers. Clang
+			 * doesn't do it. It's a GCC quirk for backwards
+			 * compatibility with code written for GCC <2.5. So,
+			 * similarly to extra qualifiers for array, just drop
+			 * them, instead of handling them.
+			 */
+			btf_dump_drop_mods(d, decls);
+			if (decls->cnt) {
+				btf_dump_printf(d, " (");
+				btf_dump_emit_type_chain(d, decls, fname, lvl);
+				btf_dump_printf(d, ")");
+			} else {
+				btf_dump_emit_name(d, fname, last_was_ptr);
+			}
+			btf_dump_printf(d, "(");
+			/*
+			 * Clang for BPF target generates func_proto with no
+			 * args as a func_proto with a single void arg (e.g.,
+			 * `int (*f)(void)` vs just `int (*f)()`). We are
+			 * going to pretend there are no args for such case.
+			 */
+			if (vlen == 1 && p->type == 0) {
+				btf_dump_printf(d, ")");
+				return;
+			}
+
+			for (i = 0; i < vlen; i++, p++) {
+				if (i > 0)
+					btf_dump_printf(d, ", ");
+
+				/* last arg of type void is vararg */
+				if (i == vlen - 1 && p->type == 0) {
+					btf_dump_printf(d, "...");
+					break;
+				}
+
+				name = btf_name_of(d, p->name_off);
+				btf_dump_emit_type_decl(d, p->type, name, lvl);
+			}
+
+			btf_dump_printf(d, ")");
+			return;
+		}
+		default:
+			pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
+				kind, id);
+			return;
+		}
+
+		last_was_ptr = kind == BTF_KIND_PTR;
+	}
+
+	btf_dump_emit_name(d, fname, last_was_ptr);
+}
+
+/* show type name as (type_name) */
+static void btf_dump_emit_type_cast(struct btf_dump *d, __u32 id,
+				    bool top_level)
+{
+	const struct btf_type *t;
+
+	/* for array members, we don't bother emitting type name for each
+	 * member to avoid the redundancy of
+	 * .name = (char[4])[(char)'f',(char)'o',(char)'o',]
+	 */
+	if (d->typed_dump->is_array_member)
+		return;
+
+	/* avoid type name specification for variable/section; it will be done
+	 * for the associated variable value(s).
+	 */
+	t = btf__type_by_id(d->btf, id);
+	if (btf_is_var(t) || btf_is_datasec(t))
+		return;
+
+	if (top_level)
+		btf_dump_printf(d, "(");
+
+	d->skip_anon_defs = true;
+	d->strip_mods = true;
+	btf_dump_emit_type_decl(d, id, "", 0);
+	d->strip_mods = false;
+	d->skip_anon_defs = false;
+
+	if (top_level)
+		btf_dump_printf(d, ")");
+}
+
+/* return number of duplicates (occurrences) of a given name */
+static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_map,
+				 const char *orig_name)
+{
+	char *old_name, *new_name;
+	size_t dup_cnt = 0;
+	int err;
+
+	new_name = strdup(orig_name);
+	if (!new_name)
+		return 1;
+
+	(void)hashmap__find(name_map, orig_name, &dup_cnt);
+	dup_cnt++;
+
+	err = hashmap__set(name_map, new_name, dup_cnt, &old_name, NULL);
+	if (err)
+		free(new_name);
+
+	free(old_name);
+
+	return dup_cnt;
+}
+
+static const char *btf_dump_resolve_name(struct btf_dump *d, __u32 id,
+					 struct hashmap *name_map)
+{
+	struct btf_dump_type_aux_state *s = &d->type_states[id];
+	const struct btf_type *t = btf__type_by_id(d->btf, id);
+	const char *orig_name = btf_name_of(d, t->name_off);
+	const char **cached_name = &d->cached_names[id];
+	size_t dup_cnt;
+
+	if (t->name_off == 0)
+		return "";
+
+	if (s->name_resolved)
+		return *cached_name ? *cached_name : orig_name;
+
+	if (btf_is_fwd(t) || (btf_is_enum(t) && btf_vlen(t) == 0)) {
+		s->name_resolved = 1;
+		return orig_name;
+	}
+
+	dup_cnt = btf_dump_name_dups(d, name_map, orig_name);
+	if (dup_cnt > 1) {
+		const size_t max_len = 256;
+		char new_name[max_len];
+
+		snprintf(new_name, max_len, "%s___%zu", orig_name, dup_cnt);
+		*cached_name = strdup(new_name);
+	}
+
+	s->name_resolved = 1;
+	return *cached_name ? *cached_name : orig_name;
+}
+
+static const char *btf_dump_type_name(struct btf_dump *d, __u32 id)
+{
+	return btf_dump_resolve_name(d, id, d->type_names);
+}
+
+static const char *btf_dump_ident_name(struct btf_dump *d, __u32 id)
+{
+	return btf_dump_resolve_name(d, id, d->ident_names);
+}
+
+static int btf_dump_dump_type_data(struct btf_dump *d,
+				   const char *fname,
+				   const struct btf_type *t,
+				   __u32 id,
+				   const void *data,
+				   __u8 bits_offset,
+				   __u8 bit_sz);
+
+static const char *btf_dump_data_newline(struct btf_dump *d)
+{
+	return d->typed_dump->compact || d->typed_dump->depth == 0 ? "" : "\n";
+}
+
+static const char *btf_dump_data_delim(struct btf_dump *d)
+{
+	return d->typed_dump->depth == 0 ? "" : ",";
+}
+
+static void btf_dump_data_pfx(struct btf_dump *d)
+{
+	int i, lvl = d->typed_dump->indent_lvl + d->typed_dump->depth;
+
+	if (d->typed_dump->compact)
+		return;
+
+	for (i = 0; i < lvl; i++)
+		btf_dump_printf(d, "%s", d->typed_dump->indent_str);
+}
+
+/* A macro is used here as btf_type_value[s]() appends format specifiers
+ * to the format specifier passed in; these do the work of appending
+ * delimiters etc while the caller simply has to specify the type values
+ * in the format specifier + value(s).
+ */
+#define btf_dump_type_values(d, fmt, ...)				\
+	btf_dump_printf(d, fmt "%s%s",					\
+			##__VA_ARGS__,					\
+			btf_dump_data_delim(d),				\
+			btf_dump_data_newline(d))
+
+static int btf_dump_unsupported_data(struct btf_dump *d,
+				     const struct btf_type *t,
+				     __u32 id)
+{
+	btf_dump_printf(d, "<unsupported kind:%u>", btf_kind(t));
+	return -ENOTSUP;
+}
+
+static int btf_dump_get_bitfield_value(struct btf_dump *d,
+				       const struct btf_type *t,
+				       const void *data,
+				       __u8 bits_offset,
+				       __u8 bit_sz,
+				       __u64 *value)
+{
+	__u16 left_shift_bits, right_shift_bits;
+	const __u8 *bytes = data;
+	__u8 nr_copy_bits;
+	__u64 num = 0;
+	int i;
+
+	/* Maximum supported bitfield size is 64 bits */
+	if (t->size > 8) {
+		pr_warn("unexpected bitfield size %d\n", t->size);
+		return -EINVAL;
+	}
+
+	/* Bitfield value retrieval is done in two steps; first relevant bytes are
+	 * stored in num, then we left/right shift num to eliminate irrelevant bits.
+	 */
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	for (i = t->size - 1; i >= 0; i--)
+		num = num * 256 + bytes[i];
+	nr_copy_bits = bit_sz + bits_offset;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+	for (i = 0; i < t->size; i++)
+		num = num * 256 + bytes[i];
+	nr_copy_bits = t->size * 8 - bits_offset;
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+	left_shift_bits = 64 - nr_copy_bits;
+	right_shift_bits = 64 - bit_sz;
+
+	*value = (num << left_shift_bits) >> right_shift_bits;
+
+	return 0;
+}
+
+static int btf_dump_bitfield_check_zero(struct btf_dump *d,
+					const struct btf_type *t,
+					const void *data,
+					__u8 bits_offset,
+					__u8 bit_sz)
+{
+	__u64 check_num;
+	int err;
+
+	err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, &check_num);
+	if (err)
+		return err;
+	if (check_num == 0)
+		return -ENODATA;
+	return 0;
+}
+
+static int btf_dump_bitfield_data(struct btf_dump *d,
+				  const struct btf_type *t,
+				  const void *data,
+				  __u8 bits_offset,
+				  __u8 bit_sz)
+{
+	__u64 print_num;
+	int err;
+
+	err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, &print_num);
+	if (err)
+		return err;
+
+	btf_dump_type_values(d, "0x%llx", (unsigned long long)print_num);
+
+	return 0;
+}
+
+/* ints, floats and ptrs */
+static int btf_dump_base_type_check_zero(struct btf_dump *d,
+					 const struct btf_type *t,
+					 __u32 id,
+					 const void *data)
+{
+	static __u8 bytecmp[16] = {};
+	int nr_bytes;
+
+	/* For pointer types, pointer size is not defined on a per-type basis.
+	 * On dump creation however, we store the pointer size.
+	 */
+	if (btf_kind(t) == BTF_KIND_PTR)
+		nr_bytes = d->ptr_sz;
+	else
+		nr_bytes = t->size;
+
+	if (nr_bytes < 1 || nr_bytes > 16) {
+		pr_warn("unexpected size %d for id [%u]\n", nr_bytes, id);
+		return -EINVAL;
+	}
+
+	if (memcmp(data, bytecmp, nr_bytes) == 0)
+		return -ENODATA;
+	return 0;
+}
+
+static bool ptr_is_aligned(const struct btf *btf, __u32 type_id,
+			   const void *data)
+{
+	int alignment = btf__align_of(btf, type_id);
+
+	if (alignment == 0)
+		return false;
+
+	return ((uintptr_t)data) % alignment == 0;
+}
+
+static int btf_dump_int_data(struct btf_dump *d,
+			     const struct btf_type *t,
+			     __u32 type_id,
+			     const void *data,
+			     __u8 bits_offset)
+{
+	__u8 encoding = btf_int_encoding(t);
+	bool sign = encoding & BTF_INT_SIGNED;
+	char buf[16] __attribute__((aligned(16)));
+	int sz = t->size;
+
+	if (sz == 0 || sz > sizeof(buf)) {
+		pr_warn("unexpected size %d for id [%u]\n", sz, type_id);
+		return -EINVAL;
+	}
+
+	/* handle packed int data - accesses of integers not aligned on
+	 * int boundaries can cause problems on some platforms.
+	 */
+	if (!ptr_is_aligned(d->btf, type_id, data)) {
+		memcpy(buf, data, sz);
+		data = buf;
+	}
+
+	switch (sz) {
+	case 16: {
+		const __u64 *ints = data;
+		__u64 lsi, msi;
+
+		/* avoid use of __int128 as some 32-bit platforms do not
+		 * support it.
+		 */
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+		lsi = ints[0];
+		msi = ints[1];
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+		lsi = ints[1];
+		msi = ints[0];
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+		if (msi == 0)
+			btf_dump_type_values(d, "0x%llx", (unsigned long long)lsi);
+		else
+			btf_dump_type_values(d, "0x%llx%016llx", (unsigned long long)msi,
+					     (unsigned long long)lsi);
+		break;
+	}
+	case 8:
+		if (sign)
+			btf_dump_type_values(d, "%lld", *(long long *)data);
+		else
+			btf_dump_type_values(d, "%llu", *(unsigned long long *)data);
+		break;
+	case 4:
+		if (sign)
+			btf_dump_type_values(d, "%d", *(__s32 *)data);
+		else
+			btf_dump_type_values(d, "%u", *(__u32 *)data);
+		break;
+	case 2:
+		if (sign)
+			btf_dump_type_values(d, "%d", *(__s16 *)data);
+		else
+			btf_dump_type_values(d, "%u", *(__u16 *)data);
+		break;
+	case 1:
+		if (d->typed_dump->is_array_char) {
+			/* check for null terminator */
+			if (d->typed_dump->is_array_terminated)
+				break;
+			if (*(char *)data == '\0') {
+				d->typed_dump->is_array_terminated = true;
+				break;
+			}
+			if (isprint(*(char *)data)) {
+				btf_dump_type_values(d, "'%c'", *(char *)data);
+				break;
+			}
+		}
+		if (sign)
+			btf_dump_type_values(d, "%d", *(__s8 *)data);
+		else
+			btf_dump_type_values(d, "%u", *(__u8 *)data);
+		break;
+	default:
+		pr_warn("unexpected sz %d for id [%u]\n", sz, type_id);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+union float_data {
+	long double ld;
+	double d;
+	float f;
+};
+
+static int btf_dump_float_data(struct btf_dump *d,
+			       const struct btf_type *t,
+			       __u32 type_id,
+			       const void *data)
+{
+	const union float_data *flp = data;
+	union float_data fl;
+	int sz = t->size;
+
+	/* handle unaligned data; copy to local union */
+	if (!ptr_is_aligned(d->btf, type_id, data)) {
+		memcpy(&fl, data, sz);
+		flp = &fl;
+	}
+
+	switch (sz) {
+	case 16:
+		btf_dump_type_values(d, "%Lf", flp->ld);
+		break;
+	case 8:
+		btf_dump_type_values(d, "%lf", flp->d);
+		break;
+	case 4:
+		btf_dump_type_values(d, "%f", flp->f);
+		break;
+	default:
+		pr_warn("unexpected size %d for id [%u]\n", sz, type_id);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int btf_dump_var_data(struct btf_dump *d,
+			     const struct btf_type *v,
+			     __u32 id,
+			     const void *data)
+{
+	enum btf_func_linkage linkage = btf_var(v)->linkage;
+	const struct btf_type *t;
+	const char *l;
+	__u32 type_id;
+
+	switch (linkage) {
+	case BTF_FUNC_STATIC:
+		l = "static ";
+		break;
+	case BTF_FUNC_EXTERN:
+		l = "extern ";
+		break;
+	case BTF_FUNC_GLOBAL:
+	default:
+		l = "";
+		break;
+	}
+
+	/* format of output here is [linkage] [type] [varname] = (type)value,
+	 * for example "static int cpu_profile_flip = (int)1"
+	 */
+	btf_dump_printf(d, "%s", l);
+	type_id = v->type;
+	t = btf__type_by_id(d->btf, type_id);
+	btf_dump_emit_type_cast(d, type_id, false);
+	btf_dump_printf(d, " %s = ", btf_name_of(d, v->name_off));
+	return btf_dump_dump_type_data(d, NULL, t, type_id, data, 0, 0);
+}
+
+static int btf_dump_array_data(struct btf_dump *d,
+			       const struct btf_type *t,
+			       __u32 id,
+			       const void *data)
+{
+	const struct btf_array *array = btf_array(t);
+	const struct btf_type *elem_type;
+	__u32 i, elem_type_id;
+	__s64 elem_size;
+	bool is_array_member;
+
+	elem_type_id = array->type;
+	elem_type = skip_mods_and_typedefs(d->btf, elem_type_id, NULL);
+	elem_size = btf__resolve_size(d->btf, elem_type_id);
+	if (elem_size <= 0) {
+		pr_warn("unexpected elem size %zd for array type [%u]\n",
+			(ssize_t)elem_size, id);
+		return -EINVAL;
+	}
+
+	if (btf_is_int(elem_type)) {
+		/*
+		 * BTF_INT_CHAR encoding never seems to be set for
+		 * char arrays, so if size is 1 and element is
+		 * printable as a char, we'll do that.
+		 */
+		if (elem_size == 1)
+			d->typed_dump->is_array_char = true;
+	}
+
+	/* note that we increment depth before calling btf_dump_print() below;
+	 * this is intentional.  btf_dump_data_newline() will not print a
+	 * newline for depth 0 (since this leaves us with trailing newlines
+	 * at the end of typed display), so depth is incremented first.
+	 * For similar reasons, we decrement depth before showing the closing
+	 * parenthesis.
+	 */
+	d->typed_dump->depth++;
+	btf_dump_printf(d, "[%s", btf_dump_data_newline(d));
+
+	/* may be a multidimensional array, so store current "is array member"
+	 * status so we can restore it correctly later.
+	 */
+	is_array_member = d->typed_dump->is_array_member;
+	d->typed_dump->is_array_member = true;
+	for (i = 0; i < array->nelems; i++, data += elem_size) {
+		if (d->typed_dump->is_array_terminated)
+			break;
+		btf_dump_dump_type_data(d, NULL, elem_type, elem_type_id, data, 0, 0);
+	}
+	d->typed_dump->is_array_member = is_array_member;
+	d->typed_dump->depth--;
+	btf_dump_data_pfx(d);
+	btf_dump_type_values(d, "]");
+
+	return 0;
+}
+
+static int btf_dump_struct_data(struct btf_dump *d,
+				const struct btf_type *t,
+				__u32 id,
+				const void *data)
+{
+	const struct btf_member *m = btf_members(t);
+	__u16 n = btf_vlen(t);
+	int i, err = 0;
+
+	/* note that we increment depth before calling btf_dump_print() below;
+	 * this is intentional.  btf_dump_data_newline() will not print a
+	 * newline for depth 0 (since this leaves us with trailing newlines
+	 * at the end of typed display), so depth is incremented first.
+	 * For similar reasons, we decrement depth before showing the closing
+	 * parenthesis.
+	 */
+	d->typed_dump->depth++;
+	btf_dump_printf(d, "{%s", btf_dump_data_newline(d));
+
+	for (i = 0; i < n; i++, m++) {
+		const struct btf_type *mtype;
+		const char *mname;
+		__u32 moffset;
+		__u8 bit_sz;
+
+		mtype = btf__type_by_id(d->btf, m->type);
+		mname = btf_name_of(d, m->name_off);
+		moffset = btf_member_bit_offset(t, i);
+
+		bit_sz = btf_member_bitfield_size(t, i);
+		err = btf_dump_dump_type_data(d, mname, mtype, m->type, data + moffset / 8,
+					      moffset % 8, bit_sz);
+		if (err < 0)
+			return err;
+	}
+	d->typed_dump->depth--;
+	btf_dump_data_pfx(d);
+	btf_dump_type_values(d, "}");
+	return err;
+}
+
+union ptr_data {
+	unsigned int p;
+	unsigned long long lp;
+};
+
+static int btf_dump_ptr_data(struct btf_dump *d,
+			      const struct btf_type *t,
+			      __u32 id,
+			      const void *data)
+{
+	if (ptr_is_aligned(d->btf, id, data) && d->ptr_sz == sizeof(void *)) {
+		btf_dump_type_values(d, "%p", *(void **)data);
+	} else {
+		union ptr_data pt;
+
+		memcpy(&pt, data, d->ptr_sz);
+		if (d->ptr_sz == 4)
+			btf_dump_type_values(d, "0x%x", pt.p);
+		else
+			btf_dump_type_values(d, "0x%llx", pt.lp);
+	}
+	return 0;
+}
+
+static int btf_dump_get_enum_value(struct btf_dump *d,
+				   const struct btf_type *t,
+				   const void *data,
+				   __u32 id,
+				   __s64 *value)
+{
+	bool is_signed = btf_kflag(t);
+
+	if (!ptr_is_aligned(d->btf, id, data)) {
+		__u64 val;
+		int err;
+
+		err = btf_dump_get_bitfield_value(d, t, data, 0, 0, &val);
+		if (err)
+			return err;
+		*value = (__s64)val;
+		return 0;
+	}
+
+	switch (t->size) {
+	case 8:
+		*value = *(__s64 *)data;
+		return 0;
+	case 4:
+		*value = is_signed ? (__s64)*(__s32 *)data : *(__u32 *)data;
+		return 0;
+	case 2:
+		*value = is_signed ? *(__s16 *)data : *(__u16 *)data;
+		return 0;
+	case 1:
+		*value = is_signed ? *(__s8 *)data : *(__u8 *)data;
+		return 0;
+	default:
+		pr_warn("unexpected size %d for enum, id:[%u]\n", t->size, id);
+		return -EINVAL;
+	}
+}
+
+static int btf_dump_enum_data(struct btf_dump *d,
+			      const struct btf_type *t,
+			      __u32 id,
+			      const void *data)
+{
+	bool is_signed;
+	__s64 value;
+	int i, err;
+
+	err = btf_dump_get_enum_value(d, t, data, id, &value);
+	if (err)
+		return err;
+
+	is_signed = btf_kflag(t);
+	if (btf_is_enum(t)) {
+		const struct btf_enum *e;
+
+		for (i = 0, e = btf_enum(t); i < btf_vlen(t); i++, e++) {
+			if (value != e->val)
+				continue;
+			btf_dump_type_values(d, "%s", btf_name_of(d, e->name_off));
+			return 0;
+		}
+
+		btf_dump_type_values(d, is_signed ? "%d" : "%u", value);
+	} else {
+		const struct btf_enum64 *e;
+
+		for (i = 0, e = btf_enum64(t); i < btf_vlen(t); i++, e++) {
+			if (value != btf_enum64_value(e))
+				continue;
+			btf_dump_type_values(d, "%s", btf_name_of(d, e->name_off));
+			return 0;
+		}
+
+		btf_dump_type_values(d, is_signed ? "%lldLL" : "%lluULL",
+				     (unsigned long long)value);
+	}
+	return 0;
+}
+
+static int btf_dump_datasec_data(struct btf_dump *d,
+				 const struct btf_type *t,
+				 __u32 id,
+				 const void *data)
+{
+	const struct btf_var_secinfo *vsi;
+	const struct btf_type *var;
+	__u32 i;
+	int err;
+
+	btf_dump_type_values(d, "SEC(\"%s\") ", btf_name_of(d, t->name_off));
+
+	for (i = 0, vsi = btf_var_secinfos(t); i < btf_vlen(t); i++, vsi++) {
+		var = btf__type_by_id(d->btf, vsi->type);
+		err = btf_dump_dump_type_data(d, NULL, var, vsi->type, data + vsi->offset, 0, 0);
+		if (err < 0)
+			return err;
+		btf_dump_printf(d, ";");
+	}
+	return 0;
+}
+
+/* return size of type, or if base type overflows, return -E2BIG. */
+static int btf_dump_type_data_check_overflow(struct btf_dump *d,
+					     const struct btf_type *t,
+					     __u32 id,
+					     const void *data,
+					     __u8 bits_offset)
+{
+	__s64 size = btf__resolve_size(d->btf, id);
+
+	if (size < 0 || size >= INT_MAX) {
+		pr_warn("unexpected size [%zu] for id [%u]\n",
+			(size_t)size, id);
+		return -EINVAL;
+	}
+
+	/* Only do overflow checking for base types; we do not want to
+	 * avoid showing part of a struct, union or array, even if we
+	 * do not have enough data to show the full object.  By
+	 * restricting overflow checking to base types we can ensure
+	 * that partial display succeeds, while avoiding overflowing
+	 * and using bogus data for display.
+	 */
+	t = skip_mods_and_typedefs(d->btf, id, NULL);
+	if (!t) {
+		pr_warn("unexpected error skipping mods/typedefs for id [%u]\n",
+			id);
+		return -EINVAL;
+	}
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_INT:
+	case BTF_KIND_FLOAT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		if (data + bits_offset / 8 + size > d->typed_dump->data_end)
+			return -E2BIG;
+		break;
+	default:
+		break;
+	}
+	return (int)size;
+}
+
+static int btf_dump_type_data_check_zero(struct btf_dump *d,
+					 const struct btf_type *t,
+					 __u32 id,
+					 const void *data,
+					 __u8 bits_offset,
+					 __u8 bit_sz)
+{
+	__s64 value;
+	int i, err;
+
+	/* toplevel exceptions; we show zero values if
+	 * - we ask for them (emit_zeros)
+	 * - if we are at top-level so we see "struct empty { }"
+	 * - or if we are an array member and the array is non-empty and
+	 *   not a char array; we don't want to be in a situation where we
+	 *   have an integer array 0, 1, 0, 1 and only show non-zero values.
+	 *   If the array contains zeroes only, or is a char array starting
+	 *   with a '\0', the array-level check_zero() will prevent showing it;
+	 *   we are concerned with determining zero value at the array member
+	 *   level here.
+	 */
+	if (d->typed_dump->emit_zeroes || d->typed_dump->depth == 0 ||
+	    (d->typed_dump->is_array_member &&
+	     !d->typed_dump->is_array_char))
+		return 0;
+
+	t = skip_mods_and_typedefs(d->btf, id, NULL);
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_INT:
+		if (bit_sz)
+			return btf_dump_bitfield_check_zero(d, t, data, bits_offset, bit_sz);
+		return btf_dump_base_type_check_zero(d, t, id, data);
+	case BTF_KIND_FLOAT:
+	case BTF_KIND_PTR:
+		return btf_dump_base_type_check_zero(d, t, id, data);
+	case BTF_KIND_ARRAY: {
+		const struct btf_array *array = btf_array(t);
+		const struct btf_type *elem_type;
+		__u32 elem_type_id, elem_size;
+		bool ischar;
+
+		elem_type_id = array->type;
+		elem_size = btf__resolve_size(d->btf, elem_type_id);
+		elem_type = skip_mods_and_typedefs(d->btf, elem_type_id, NULL);
+
+		ischar = btf_is_int(elem_type) && elem_size == 1;
+
+		/* check all elements; if _any_ element is nonzero, all
+		 * of array is displayed.  We make an exception however
+		 * for char arrays where the first element is 0; these
+		 * are considered zeroed also, even if later elements are
+		 * non-zero because the string is terminated.
+		 */
+		for (i = 0; i < array->nelems; i++) {
+			if (i == 0 && ischar && *(char *)data == 0)
+				return -ENODATA;
+			err = btf_dump_type_data_check_zero(d, elem_type,
+							    elem_type_id,
+							    data +
+							    (i * elem_size),
+							    bits_offset, 0);
+			if (err != -ENODATA)
+				return err;
+		}
+		return -ENODATA;
+	}
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		const struct btf_member *m = btf_members(t);
+		__u16 n = btf_vlen(t);
+
+		/* if any struct/union member is non-zero, the struct/union
+		 * is considered non-zero and dumped.
+		 */
+		for (i = 0; i < n; i++, m++) {
+			const struct btf_type *mtype;
+			__u32 moffset;
+
+			mtype = btf__type_by_id(d->btf, m->type);
+			moffset = btf_member_bit_offset(t, i);
+
+			/* btf_int_bits() does not store member bitfield size;
+			 * bitfield size needs to be stored here so int display
+			 * of member can retrieve it.
+			 */
+			bit_sz = btf_member_bitfield_size(t, i);
+			err = btf_dump_type_data_check_zero(d, mtype, m->type, data + moffset / 8,
+							    moffset % 8, bit_sz);
+			if (err != ENODATA)
+				return err;
+		}
+		return -ENODATA;
+	}
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		err = btf_dump_get_enum_value(d, t, data, id, &value);
+		if (err)
+			return err;
+		if (value == 0)
+			return -ENODATA;
+		return 0;
+	default:
+		return 0;
+	}
+}
+
+/* returns size of data dumped, or error. */
+static int btf_dump_dump_type_data(struct btf_dump *d,
+				   const char *fname,
+				   const struct btf_type *t,
+				   __u32 id,
+				   const void *data,
+				   __u8 bits_offset,
+				   __u8 bit_sz)
+{
+	int size, err = 0;
+
+	size = btf_dump_type_data_check_overflow(d, t, id, data, bits_offset);
+	if (size < 0)
+		return size;
+	err = btf_dump_type_data_check_zero(d, t, id, data, bits_offset, bit_sz);
+	if (err) {
+		/* zeroed data is expected and not an error, so simply skip
+		 * dumping such data.  Record other errors however.
+		 */
+		if (err == -ENODATA)
+			return size;
+		return err;
+	}
+	btf_dump_data_pfx(d);
+
+	if (!d->typed_dump->skip_names) {
+		if (fname && strlen(fname) > 0)
+			btf_dump_printf(d, ".%s = ", fname);
+		btf_dump_emit_type_cast(d, id, true);
+	}
+
+	t = skip_mods_and_typedefs(d->btf, id, NULL);
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_UNKN:
+	case BTF_KIND_FWD:
+	case BTF_KIND_FUNC:
+	case BTF_KIND_FUNC_PROTO:
+	case BTF_KIND_DECL_TAG:
+		err = btf_dump_unsupported_data(d, t, id);
+		break;
+	case BTF_KIND_INT:
+		if (bit_sz)
+			err = btf_dump_bitfield_data(d, t, data, bits_offset, bit_sz);
+		else
+			err = btf_dump_int_data(d, t, id, data, bits_offset);
+		break;
+	case BTF_KIND_FLOAT:
+		err = btf_dump_float_data(d, t, id, data);
+		break;
+	case BTF_KIND_PTR:
+		err = btf_dump_ptr_data(d, t, id, data);
+		break;
+	case BTF_KIND_ARRAY:
+		err = btf_dump_array_data(d, t, id, data);
+		break;
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+		err = btf_dump_struct_data(d, t, id, data);
+		break;
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		/* handle bitfield and int enum values */
+		if (bit_sz) {
+			__u64 print_num;
+			__s64 enum_val;
+
+			err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz,
+							  &print_num);
+			if (err)
+				break;
+			enum_val = (__s64)print_num;
+			err = btf_dump_enum_data(d, t, id, &enum_val);
+		} else
+			err = btf_dump_enum_data(d, t, id, data);
+		break;
+	case BTF_KIND_VAR:
+		err = btf_dump_var_data(d, t, id, data);
+		break;
+	case BTF_KIND_DATASEC:
+		err = btf_dump_datasec_data(d, t, id, data);
+		break;
+	default:
+		pr_warn("unexpected kind [%u] for id [%u]\n",
+			BTF_INFO_KIND(t->info), id);
+		return -EINVAL;
+	}
+	if (err < 0)
+		return err;
+	return size;
+}
+
+int btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
+			     const void *data, size_t data_sz,
+			     const struct btf_dump_type_data_opts *opts)
+{
+	struct btf_dump_data typed_dump = {};
+	const struct btf_type *t;
+	int ret;
+
+	if (!OPTS_VALID(opts, btf_dump_type_data_opts))
+		return libbpf_err(-EINVAL);
+
+	t = btf__type_by_id(d->btf, id);
+	if (!t)
+		return libbpf_err(-ENOENT);
+
+	d->typed_dump = &typed_dump;
+	d->typed_dump->data_end = data + data_sz;
+	d->typed_dump->indent_lvl = OPTS_GET(opts, indent_level, 0);
+
+	/* default indent string is a tab */
+	if (!OPTS_GET(opts, indent_str, NULL))
+		d->typed_dump->indent_str[0] = '\t';
+	else
+		libbpf_strlcpy(d->typed_dump->indent_str, opts->indent_str,
+			       sizeof(d->typed_dump->indent_str));
+
+	d->typed_dump->compact = OPTS_GET(opts, compact, false);
+	d->typed_dump->skip_names = OPTS_GET(opts, skip_names, false);
+	d->typed_dump->emit_zeroes = OPTS_GET(opts, emit_zeroes, false);
+
+	ret = btf_dump_dump_type_data(d, NULL, t, id, data, 0, 0);
+
+	d->typed_dump = NULL;
+
+	return libbpf_err(ret);
+}
diff --git a/src/gen_loader.c b/src/gen_loader.c
new file mode 100644
index 0000000..23f5c46
--- /dev/null
+++ b/src/gen_loader.c
@@ -0,0 +1,1121 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2021 Facebook */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <linux/filter.h>
+#include <sys/param.h>
+#include "btf.h"
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+#include "hashmap.h"
+#include "bpf_gen_internal.h"
+#include "skel_internal.h"
+#include <asm/byteorder.h>
+
+#define MAX_USED_MAPS	64
+#define MAX_USED_PROGS	32
+#define MAX_KFUNC_DESCS 256
+#define MAX_FD_ARRAY_SZ (MAX_USED_MAPS + MAX_KFUNC_DESCS)
+
+/* The following structure describes the stack layout of the loader program.
+ * In addition R6 contains the pointer to context.
+ * R7 contains the result of the last sys_bpf command (typically error or FD).
+ * R9 contains the result of the last sys_close command.
+ *
+ * Naming convention:
+ * ctx - bpf program context
+ * stack - bpf program stack
+ * blob - bpf_attr-s, strings, insns, map data.
+ *        All the bytes that loader prog will use for read/write.
+ */
+struct loader_stack {
+	__u32 btf_fd;
+	__u32 inner_map_fd;
+	__u32 prog_fd[MAX_USED_PROGS];
+};
+
+#define stack_off(field) \
+	(__s16)(-sizeof(struct loader_stack) + offsetof(struct loader_stack, field))
+
+#define attr_field(attr, field) (attr + offsetof(union bpf_attr, field))
+
+static int blob_fd_array_off(struct bpf_gen *gen, int index)
+{
+	return gen->fd_array + index * sizeof(int);
+}
+
+static int realloc_insn_buf(struct bpf_gen *gen, __u32 size)
+{
+	size_t off = gen->insn_cur - gen->insn_start;
+	void *insn_start;
+
+	if (gen->error)
+		return gen->error;
+	if (size > INT32_MAX || off + size > INT32_MAX) {
+		gen->error = -ERANGE;
+		return -ERANGE;
+	}
+	insn_start = realloc(gen->insn_start, off + size);
+	if (!insn_start) {
+		gen->error = -ENOMEM;
+		free(gen->insn_start);
+		gen->insn_start = NULL;
+		return -ENOMEM;
+	}
+	gen->insn_start = insn_start;
+	gen->insn_cur = insn_start + off;
+	return 0;
+}
+
+static int realloc_data_buf(struct bpf_gen *gen, __u32 size)
+{
+	size_t off = gen->data_cur - gen->data_start;
+	void *data_start;
+
+	if (gen->error)
+		return gen->error;
+	if (size > INT32_MAX || off + size > INT32_MAX) {
+		gen->error = -ERANGE;
+		return -ERANGE;
+	}
+	data_start = realloc(gen->data_start, off + size);
+	if (!data_start) {
+		gen->error = -ENOMEM;
+		free(gen->data_start);
+		gen->data_start = NULL;
+		return -ENOMEM;
+	}
+	gen->data_start = data_start;
+	gen->data_cur = data_start + off;
+	return 0;
+}
+
+static void emit(struct bpf_gen *gen, struct bpf_insn insn)
+{
+	if (realloc_insn_buf(gen, sizeof(insn)))
+		return;
+	memcpy(gen->insn_cur, &insn, sizeof(insn));
+	gen->insn_cur += sizeof(insn);
+}
+
+static void emit2(struct bpf_gen *gen, struct bpf_insn insn1, struct bpf_insn insn2)
+{
+	emit(gen, insn1);
+	emit(gen, insn2);
+}
+
+static int add_data(struct bpf_gen *gen, const void *data, __u32 size);
+static void emit_sys_close_blob(struct bpf_gen *gen, int blob_off);
+
+void bpf_gen__init(struct bpf_gen *gen, int log_level, int nr_progs, int nr_maps)
+{
+	size_t stack_sz = sizeof(struct loader_stack), nr_progs_sz;
+	int i;
+
+	gen->fd_array = add_data(gen, NULL, MAX_FD_ARRAY_SZ * sizeof(int));
+	gen->log_level = log_level;
+	/* save ctx pointer into R6 */
+	emit(gen, BPF_MOV64_REG(BPF_REG_6, BPF_REG_1));
+
+	/* bzero stack */
+	emit(gen, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
+	emit(gen, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -stack_sz));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_2, stack_sz));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_3, 0));
+	emit(gen, BPF_EMIT_CALL(BPF_FUNC_probe_read_kernel));
+
+	/* amount of stack actually used, only used to calculate iterations, not stack offset */
+	nr_progs_sz = offsetof(struct loader_stack, prog_fd[nr_progs]);
+	/* jump over cleanup code */
+	emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0,
+			      /* size of cleanup code below (including map fd cleanup) */
+			      (nr_progs_sz / 4) * 3 + 2 +
+			      /* 6 insns for emit_sys_close_blob,
+			       * 6 insns for debug_regs in emit_sys_close_blob
+			       */
+			      nr_maps * (6 + (gen->log_level ? 6 : 0))));
+
+	/* remember the label where all error branches will jump to */
+	gen->cleanup_label = gen->insn_cur - gen->insn_start;
+	/* emit cleanup code: close all temp FDs */
+	for (i = 0; i < nr_progs_sz; i += 4) {
+		emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, -stack_sz + i));
+		emit(gen, BPF_JMP_IMM(BPF_JSLE, BPF_REG_1, 0, 1));
+		emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_close));
+	}
+	for (i = 0; i < nr_maps; i++)
+		emit_sys_close_blob(gen, blob_fd_array_off(gen, i));
+	/* R7 contains the error code from sys_bpf. Copy it into R0 and exit. */
+	emit(gen, BPF_MOV64_REG(BPF_REG_0, BPF_REG_7));
+	emit(gen, BPF_EXIT_INSN());
+}
+
+static int add_data(struct bpf_gen *gen, const void *data, __u32 size)
+{
+	__u32 size8 = roundup(size, 8);
+	__u64 zero = 0;
+	void *prev;
+
+	if (realloc_data_buf(gen, size8))
+		return 0;
+	prev = gen->data_cur;
+	if (data) {
+		memcpy(gen->data_cur, data, size);
+		memcpy(gen->data_cur + size, &zero, size8 - size);
+	} else {
+		memset(gen->data_cur, 0, size8);
+	}
+	gen->data_cur += size8;
+	return prev - gen->data_start;
+}
+
+/* Get index for map_fd/btf_fd slot in reserved fd_array, or in data relative
+ * to start of fd_array. Caller can decide if it is usable or not.
+ */
+static int add_map_fd(struct bpf_gen *gen)
+{
+	if (gen->nr_maps == MAX_USED_MAPS) {
+		pr_warn("Total maps exceeds %d\n", MAX_USED_MAPS);
+		gen->error = -E2BIG;
+		return 0;
+	}
+	return gen->nr_maps++;
+}
+
+static int add_kfunc_btf_fd(struct bpf_gen *gen)
+{
+	int cur;
+
+	if (gen->nr_fd_array == MAX_KFUNC_DESCS) {
+		cur = add_data(gen, NULL, sizeof(int));
+		return (cur - gen->fd_array) / sizeof(int);
+	}
+	return MAX_USED_MAPS + gen->nr_fd_array++;
+}
+
+static int insn_bytes_to_bpf_size(__u32 sz)
+{
+	switch (sz) {
+	case 8: return BPF_DW;
+	case 4: return BPF_W;
+	case 2: return BPF_H;
+	case 1: return BPF_B;
+	default: return -1;
+	}
+}
+
+/* *(u64 *)(blob + off) = (u64)(void *)(blob + data) */
+static void emit_rel_store(struct bpf_gen *gen, int off, int data)
+{
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, data));
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, off));
+	emit(gen, BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, 0));
+}
+
+static void move_blob2blob(struct bpf_gen *gen, int off, int size, int blob_off)
+{
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_2, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, blob_off));
+	emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_2, 0));
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, off));
+	emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_1, BPF_REG_0, 0));
+}
+
+static void move_blob2ctx(struct bpf_gen *gen, int ctx_off, int size, int blob_off)
+{
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, blob_off));
+	emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_1, 0));
+	emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_6, BPF_REG_0, ctx_off));
+}
+
+static void move_ctx2blob(struct bpf_gen *gen, int off, int size, int ctx_off,
+				   bool check_non_zero)
+{
+	emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_6, ctx_off));
+	if (check_non_zero)
+		/* If value in ctx is zero don't update the blob.
+		 * For example: when ctx->map.max_entries == 0, keep default max_entries from bpf.c
+		 */
+		emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3));
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, off));
+	emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_1, BPF_REG_0, 0));
+}
+
+static void move_stack2blob(struct bpf_gen *gen, int off, int size, int stack_off)
+{
+	emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_10, stack_off));
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, off));
+	emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_1, BPF_REG_0, 0));
+}
+
+static void move_stack2ctx(struct bpf_gen *gen, int ctx_off, int size, int stack_off)
+{
+	emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_10, stack_off));
+	emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_6, BPF_REG_0, ctx_off));
+}
+
+static void emit_sys_bpf(struct bpf_gen *gen, int cmd, int attr, int attr_size)
+{
+	emit(gen, BPF_MOV64_IMM(BPF_REG_1, cmd));
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_2, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, attr));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_3, attr_size));
+	emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_bpf));
+	/* remember the result in R7 */
+	emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
+}
+
+static bool is_simm16(__s64 value)
+{
+	return value == (__s64)(__s16)value;
+}
+
+static void emit_check_err(struct bpf_gen *gen)
+{
+	__s64 off = -(gen->insn_cur - gen->insn_start - gen->cleanup_label) / 8 - 1;
+
+	/* R7 contains result of last sys_bpf command.
+	 * if (R7 < 0) goto cleanup;
+	 */
+	if (is_simm16(off)) {
+		emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, off));
+	} else {
+		gen->error = -ERANGE;
+		emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, -1));
+	}
+}
+
+/* reg1 and reg2 should not be R1 - R5. They can be R0, R6 - R10 */
+static void emit_debug(struct bpf_gen *gen, int reg1, int reg2,
+		       const char *fmt, va_list args)
+{
+	char buf[1024];
+	int addr, len, ret;
+
+	if (!gen->log_level)
+		return;
+	ret = vsnprintf(buf, sizeof(buf), fmt, args);
+	if (ret < 1024 - 7 && reg1 >= 0 && reg2 < 0)
+		/* The special case to accommodate common debug_ret():
+		 * to avoid specifying BPF_REG_7 and adding " r=%%d" to
+		 * prints explicitly.
+		 */
+		strcat(buf, " r=%d");
+	len = strlen(buf) + 1;
+	addr = add_data(gen, buf, len);
+
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, addr));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
+	if (reg1 >= 0)
+		emit(gen, BPF_MOV64_REG(BPF_REG_3, reg1));
+	if (reg2 >= 0)
+		emit(gen, BPF_MOV64_REG(BPF_REG_4, reg2));
+	emit(gen, BPF_EMIT_CALL(BPF_FUNC_trace_printk));
+}
+
+static void debug_regs(struct bpf_gen *gen, int reg1, int reg2, const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	emit_debug(gen, reg1, reg2, fmt, args);
+	va_end(args);
+}
+
+static void debug_ret(struct bpf_gen *gen, const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	emit_debug(gen, BPF_REG_7, -1, fmt, args);
+	va_end(args);
+}
+
+static void __emit_sys_close(struct bpf_gen *gen)
+{
+	emit(gen, BPF_JMP_IMM(BPF_JSLE, BPF_REG_1, 0,
+			      /* 2 is the number of the following insns
+			       * * 6 is additional insns in debug_regs
+			       */
+			      2 + (gen->log_level ? 6 : 0)));
+	emit(gen, BPF_MOV64_REG(BPF_REG_9, BPF_REG_1));
+	emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_close));
+	debug_regs(gen, BPF_REG_9, BPF_REG_0, "close(%%d) = %%d");
+}
+
+static void emit_sys_close_stack(struct bpf_gen *gen, int stack_off)
+{
+	emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, stack_off));
+	__emit_sys_close(gen);
+}
+
+static void emit_sys_close_blob(struct bpf_gen *gen, int blob_off)
+{
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, blob_off));
+	emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, 0));
+	__emit_sys_close(gen);
+}
+
+int bpf_gen__finish(struct bpf_gen *gen, int nr_progs, int nr_maps)
+{
+	int i;
+
+	if (nr_progs < gen->nr_progs || nr_maps != gen->nr_maps) {
+		pr_warn("nr_progs %d/%d nr_maps %d/%d mismatch\n",
+			nr_progs, gen->nr_progs, nr_maps, gen->nr_maps);
+		gen->error = -EFAULT;
+		return gen->error;
+	}
+	emit_sys_close_stack(gen, stack_off(btf_fd));
+	for (i = 0; i < gen->nr_progs; i++)
+		move_stack2ctx(gen,
+			       sizeof(struct bpf_loader_ctx) +
+			       sizeof(struct bpf_map_desc) * gen->nr_maps +
+			       sizeof(struct bpf_prog_desc) * i +
+			       offsetof(struct bpf_prog_desc, prog_fd), 4,
+			       stack_off(prog_fd[i]));
+	for (i = 0; i < gen->nr_maps; i++)
+		move_blob2ctx(gen,
+			      sizeof(struct bpf_loader_ctx) +
+			      sizeof(struct bpf_map_desc) * i +
+			      offsetof(struct bpf_map_desc, map_fd), 4,
+			      blob_fd_array_off(gen, i));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_0, 0));
+	emit(gen, BPF_EXIT_INSN());
+	pr_debug("gen: finish %d\n", gen->error);
+	if (!gen->error) {
+		struct gen_loader_opts *opts = gen->opts;
+
+		opts->insns = gen->insn_start;
+		opts->insns_sz = gen->insn_cur - gen->insn_start;
+		opts->data = gen->data_start;
+		opts->data_sz = gen->data_cur - gen->data_start;
+	}
+	return gen->error;
+}
+
+void bpf_gen__free(struct bpf_gen *gen)
+{
+	if (!gen)
+		return;
+	free(gen->data_start);
+	free(gen->insn_start);
+	free(gen);
+}
+
+void bpf_gen__load_btf(struct bpf_gen *gen, const void *btf_raw_data,
+		       __u32 btf_raw_size)
+{
+	int attr_size = offsetofend(union bpf_attr, btf_log_level);
+	int btf_data, btf_load_attr;
+	union bpf_attr attr;
+
+	memset(&attr, 0, attr_size);
+	pr_debug("gen: load_btf: size %d\n", btf_raw_size);
+	btf_data = add_data(gen, btf_raw_data, btf_raw_size);
+
+	attr.btf_size = btf_raw_size;
+	btf_load_attr = add_data(gen, &attr, attr_size);
+
+	/* populate union bpf_attr with user provided log details */
+	move_ctx2blob(gen, attr_field(btf_load_attr, btf_log_level), 4,
+		      offsetof(struct bpf_loader_ctx, log_level), false);
+	move_ctx2blob(gen, attr_field(btf_load_attr, btf_log_size), 4,
+		      offsetof(struct bpf_loader_ctx, log_size), false);
+	move_ctx2blob(gen, attr_field(btf_load_attr, btf_log_buf), 8,
+		      offsetof(struct bpf_loader_ctx, log_buf), false);
+	/* populate union bpf_attr with a pointer to the BTF data */
+	emit_rel_store(gen, attr_field(btf_load_attr, btf), btf_data);
+	/* emit BTF_LOAD command */
+	emit_sys_bpf(gen, BPF_BTF_LOAD, btf_load_attr, attr_size);
+	debug_ret(gen, "btf_load size %d", btf_raw_size);
+	emit_check_err(gen);
+	/* remember btf_fd in the stack, if successful */
+	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_7, stack_off(btf_fd)));
+}
+
+void bpf_gen__map_create(struct bpf_gen *gen,
+			 enum bpf_map_type map_type,
+			 const char *map_name,
+			 __u32 key_size, __u32 value_size, __u32 max_entries,
+			 struct bpf_map_create_opts *map_attr, int map_idx)
+{
+	int attr_size = offsetofend(union bpf_attr, map_extra);
+	bool close_inner_map_fd = false;
+	int map_create_attr, idx;
+	union bpf_attr attr;
+
+	memset(&attr, 0, attr_size);
+	attr.map_type = map_type;
+	attr.key_size = key_size;
+	attr.value_size = value_size;
+	attr.map_flags = map_attr->map_flags;
+	attr.map_extra = map_attr->map_extra;
+	if (map_name)
+		libbpf_strlcpy(attr.map_name, map_name, sizeof(attr.map_name));
+	attr.numa_node = map_attr->numa_node;
+	attr.map_ifindex = map_attr->map_ifindex;
+	attr.max_entries = max_entries;
+	attr.btf_key_type_id = map_attr->btf_key_type_id;
+	attr.btf_value_type_id = map_attr->btf_value_type_id;
+
+	pr_debug("gen: map_create: %s idx %d type %d value_type_id %d\n",
+		 attr.map_name, map_idx, map_type, attr.btf_value_type_id);
+
+	map_create_attr = add_data(gen, &attr, attr_size);
+	if (attr.btf_value_type_id)
+		/* populate union bpf_attr with btf_fd saved in the stack earlier */
+		move_stack2blob(gen, attr_field(map_create_attr, btf_fd), 4,
+				stack_off(btf_fd));
+	switch (attr.map_type) {
+	case BPF_MAP_TYPE_ARRAY_OF_MAPS:
+	case BPF_MAP_TYPE_HASH_OF_MAPS:
+		move_stack2blob(gen, attr_field(map_create_attr, inner_map_fd), 4,
+				stack_off(inner_map_fd));
+		close_inner_map_fd = true;
+		break;
+	default:
+		break;
+	}
+	/* conditionally update max_entries */
+	if (map_idx >= 0)
+		move_ctx2blob(gen, attr_field(map_create_attr, max_entries), 4,
+			      sizeof(struct bpf_loader_ctx) +
+			      sizeof(struct bpf_map_desc) * map_idx +
+			      offsetof(struct bpf_map_desc, max_entries),
+			      true /* check that max_entries != 0 */);
+	/* emit MAP_CREATE command */
+	emit_sys_bpf(gen, BPF_MAP_CREATE, map_create_attr, attr_size);
+	debug_ret(gen, "map_create %s idx %d type %d value_size %d value_btf_id %d",
+		  attr.map_name, map_idx, map_type, value_size,
+		  attr.btf_value_type_id);
+	emit_check_err(gen);
+	/* remember map_fd in the stack, if successful */
+	if (map_idx < 0) {
+		/* This bpf_gen__map_create() function is called with map_idx >= 0
+		 * for all maps that libbpf loading logic tracks.
+		 * It's called with -1 to create an inner map.
+		 */
+		emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_7,
+				      stack_off(inner_map_fd)));
+	} else if (map_idx != gen->nr_maps) {
+		gen->error = -EDOM; /* internal bug */
+		return;
+	} else {
+		/* add_map_fd does gen->nr_maps++ */
+		idx = add_map_fd(gen);
+		emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+						 0, 0, 0, blob_fd_array_off(gen, idx)));
+		emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_7, 0));
+	}
+	if (close_inner_map_fd)
+		emit_sys_close_stack(gen, stack_off(inner_map_fd));
+}
+
+void bpf_gen__record_attach_target(struct bpf_gen *gen, const char *attach_name,
+				   enum bpf_attach_type type)
+{
+	const char *prefix;
+	int kind, ret;
+
+	btf_get_kernel_prefix_kind(type, &prefix, &kind);
+	gen->attach_kind = kind;
+	ret = snprintf(gen->attach_target, sizeof(gen->attach_target), "%s%s",
+		       prefix, attach_name);
+	if (ret >= sizeof(gen->attach_target))
+		gen->error = -ENOSPC;
+}
+
+static void emit_find_attach_target(struct bpf_gen *gen)
+{
+	int name, len = strlen(gen->attach_target) + 1;
+
+	pr_debug("gen: find_attach_tgt %s %d\n", gen->attach_target, gen->attach_kind);
+	name = add_data(gen, gen->attach_target, len);
+
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, name));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_3, gen->attach_kind));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_4, 0));
+	emit(gen, BPF_EMIT_CALL(BPF_FUNC_btf_find_by_name_kind));
+	emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
+	debug_ret(gen, "find_by_name_kind(%s,%d)",
+		  gen->attach_target, gen->attach_kind);
+	emit_check_err(gen);
+	/* if successful, btf_id is in lower 32-bit of R7 and
+	 * btf_obj_fd is in upper 32-bit
+	 */
+}
+
+void bpf_gen__record_extern(struct bpf_gen *gen, const char *name, bool is_weak,
+			    bool is_typeless, int kind, int insn_idx)
+{
+	struct ksym_relo_desc *relo;
+
+	relo = libbpf_reallocarray(gen->relos, gen->relo_cnt + 1, sizeof(*relo));
+	if (!relo) {
+		gen->error = -ENOMEM;
+		return;
+	}
+	gen->relos = relo;
+	relo += gen->relo_cnt;
+	relo->name = name;
+	relo->is_weak = is_weak;
+	relo->is_typeless = is_typeless;
+	relo->kind = kind;
+	relo->insn_idx = insn_idx;
+	gen->relo_cnt++;
+}
+
+/* returns existing ksym_desc with ref incremented, or inserts a new one */
+static struct ksym_desc *get_ksym_desc(struct bpf_gen *gen, struct ksym_relo_desc *relo)
+{
+	struct ksym_desc *kdesc;
+	int i;
+
+	for (i = 0; i < gen->nr_ksyms; i++) {
+		if (!strcmp(gen->ksyms[i].name, relo->name)) {
+			gen->ksyms[i].ref++;
+			return &gen->ksyms[i];
+		}
+	}
+	kdesc = libbpf_reallocarray(gen->ksyms, gen->nr_ksyms + 1, sizeof(*kdesc));
+	if (!kdesc) {
+		gen->error = -ENOMEM;
+		return NULL;
+	}
+	gen->ksyms = kdesc;
+	kdesc = &gen->ksyms[gen->nr_ksyms++];
+	kdesc->name = relo->name;
+	kdesc->kind = relo->kind;
+	kdesc->ref = 1;
+	kdesc->off = 0;
+	kdesc->insn = 0;
+	return kdesc;
+}
+
+/* Overwrites BPF_REG_{0, 1, 2, 3, 4, 7}
+ * Returns result in BPF_REG_7
+ */
+static void emit_bpf_find_by_name_kind(struct bpf_gen *gen, struct ksym_relo_desc *relo)
+{
+	int name_off, len = strlen(relo->name) + 1;
+
+	name_off = add_data(gen, relo->name, len);
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, name_off));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_3, relo->kind));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_4, 0));
+	emit(gen, BPF_EMIT_CALL(BPF_FUNC_btf_find_by_name_kind));
+	emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
+	debug_ret(gen, "find_by_name_kind(%s,%d)", relo->name, relo->kind);
+}
+
+/* Overwrites BPF_REG_{0, 1, 2, 3, 4, 7}
+ * Returns result in BPF_REG_7
+ * Returns u64 symbol addr in BPF_REG_9
+ */
+static void emit_bpf_kallsyms_lookup_name(struct bpf_gen *gen, struct ksym_relo_desc *relo)
+{
+	int name_off, len = strlen(relo->name) + 1, res_off;
+
+	name_off = add_data(gen, relo->name, len);
+	res_off = add_data(gen, NULL, 8); /* res is u64 */
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, name_off));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_3, 0));
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_4, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, res_off));
+	emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_4));
+	emit(gen, BPF_EMIT_CALL(BPF_FUNC_kallsyms_lookup_name));
+	emit(gen, BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0));
+	emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
+	debug_ret(gen, "kallsyms_lookup_name(%s,%d)", relo->name, relo->kind);
+}
+
+/* Expects:
+ * BPF_REG_8 - pointer to instruction
+ *
+ * We need to reuse BTF fd for same symbol otherwise each relocation takes a new
+ * index, while kernel limits total kfunc BTFs to 256. For duplicate symbols,
+ * this would mean a new BTF fd index for each entry. By pairing symbol name
+ * with index, we get the insn->imm, insn->off pairing that kernel uses for
+ * kfunc_tab, which becomes the effective limit even though all of them may
+ * share same index in fd_array (such that kfunc_btf_tab has 1 element).
+ */
+static void emit_relo_kfunc_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insn)
+{
+	struct ksym_desc *kdesc;
+	int btf_fd_idx;
+
+	kdesc = get_ksym_desc(gen, relo);
+	if (!kdesc)
+		return;
+	/* try to copy from existing bpf_insn */
+	if (kdesc->ref > 1) {
+		move_blob2blob(gen, insn + offsetof(struct bpf_insn, imm), 4,
+			       kdesc->insn + offsetof(struct bpf_insn, imm));
+		move_blob2blob(gen, insn + offsetof(struct bpf_insn, off), 2,
+			       kdesc->insn + offsetof(struct bpf_insn, off));
+		goto log;
+	}
+	/* remember insn offset, so we can copy BTF ID and FD later */
+	kdesc->insn = insn;
+	emit_bpf_find_by_name_kind(gen, relo);
+	if (!relo->is_weak)
+		emit_check_err(gen);
+	/* get index in fd_array to store BTF FD at */
+	btf_fd_idx = add_kfunc_btf_fd(gen);
+	if (btf_fd_idx > INT16_MAX) {
+		pr_warn("BTF fd off %d for kfunc %s exceeds INT16_MAX, cannot process relocation\n",
+			btf_fd_idx, relo->name);
+		gen->error = -E2BIG;
+		return;
+	}
+	kdesc->off = btf_fd_idx;
+	/* jump to success case */
+	emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 3));
+	/* set value for imm, off as 0 */
+	emit(gen, BPF_ST_MEM(BPF_W, BPF_REG_8, offsetof(struct bpf_insn, imm), 0));
+	emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), 0));
+	/* skip success case for ret < 0 */
+	emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 10));
+	/* store btf_id into insn[insn_idx].imm */
+	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7, offsetof(struct bpf_insn, imm)));
+	/* obtain fd in BPF_REG_9 */
+	emit(gen, BPF_MOV64_REG(BPF_REG_9, BPF_REG_7));
+	emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_9, 32));
+	/* jump to fd_array store if fd denotes module BTF */
+	emit(gen, BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0, 2));
+	/* set the default value for off */
+	emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), 0));
+	/* skip BTF fd store for vmlinux BTF */
+	emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 4));
+	/* load fd_array slot pointer */
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, blob_fd_array_off(gen, btf_fd_idx)));
+	/* store BTF fd in slot */
+	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_9, 0));
+	/* store index into insn[insn_idx].off */
+	emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), btf_fd_idx));
+log:
+	if (!gen->log_level)
+		return;
+	emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_8,
+			      offsetof(struct bpf_insn, imm)));
+	emit(gen, BPF_LDX_MEM(BPF_H, BPF_REG_9, BPF_REG_8,
+			      offsetof(struct bpf_insn, off)));
+	debug_regs(gen, BPF_REG_7, BPF_REG_9, " func (%s:count=%d): imm: %%d, off: %%d",
+		   relo->name, kdesc->ref);
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, blob_fd_array_off(gen, kdesc->off)));
+	emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_0, 0));
+	debug_regs(gen, BPF_REG_9, -1, " func (%s:count=%d): btf_fd",
+		   relo->name, kdesc->ref);
+}
+
+static void emit_ksym_relo_log(struct bpf_gen *gen, struct ksym_relo_desc *relo,
+			       int ref)
+{
+	if (!gen->log_level)
+		return;
+	emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_8,
+			      offsetof(struct bpf_insn, imm)));
+	emit(gen, BPF_LDX_MEM(BPF_H, BPF_REG_9, BPF_REG_8, sizeof(struct bpf_insn) +
+			      offsetof(struct bpf_insn, imm)));
+	debug_regs(gen, BPF_REG_7, BPF_REG_9, " var t=%d w=%d (%s:count=%d): imm[0]: %%d, imm[1]: %%d",
+		   relo->is_typeless, relo->is_weak, relo->name, ref);
+	emit(gen, BPF_LDX_MEM(BPF_B, BPF_REG_9, BPF_REG_8, offsetofend(struct bpf_insn, code)));
+	debug_regs(gen, BPF_REG_9, -1, " var t=%d w=%d (%s:count=%d): insn.reg",
+		   relo->is_typeless, relo->is_weak, relo->name, ref);
+}
+
+/* Expects:
+ * BPF_REG_8 - pointer to instruction
+ */
+static void emit_relo_ksym_typeless(struct bpf_gen *gen,
+				    struct ksym_relo_desc *relo, int insn)
+{
+	struct ksym_desc *kdesc;
+
+	kdesc = get_ksym_desc(gen, relo);
+	if (!kdesc)
+		return;
+	/* try to copy from existing ldimm64 insn */
+	if (kdesc->ref > 1) {
+		move_blob2blob(gen, insn + offsetof(struct bpf_insn, imm), 4,
+			       kdesc->insn + offsetof(struct bpf_insn, imm));
+		move_blob2blob(gen, insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm), 4,
+			       kdesc->insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm));
+		goto log;
+	}
+	/* remember insn offset, so we can copy ksym addr later */
+	kdesc->insn = insn;
+	/* skip typeless ksym_desc in fd closing loop in cleanup_relos */
+	kdesc->typeless = true;
+	emit_bpf_kallsyms_lookup_name(gen, relo);
+	emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_7, -ENOENT, 1));
+	emit_check_err(gen);
+	/* store lower half of addr into insn[insn_idx].imm */
+	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_9, offsetof(struct bpf_insn, imm)));
+	/* store upper half of addr into insn[insn_idx + 1].imm */
+	emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_9, 32));
+	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_9,
+		      sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm)));
+log:
+	emit_ksym_relo_log(gen, relo, kdesc->ref);
+}
+
+static __u32 src_reg_mask(void)
+{
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	return 0x0f; /* src_reg,dst_reg,... */
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	return 0xf0; /* dst_reg,src_reg,... */
+#else
+#error "Unsupported bit endianness, cannot proceed"
+#endif
+}
+
+/* Expects:
+ * BPF_REG_8 - pointer to instruction
+ */
+static void emit_relo_ksym_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insn)
+{
+	struct ksym_desc *kdesc;
+	__u32 reg_mask;
+
+	kdesc = get_ksym_desc(gen, relo);
+	if (!kdesc)
+		return;
+	/* try to copy from existing ldimm64 insn */
+	if (kdesc->ref > 1) {
+		move_blob2blob(gen, insn + offsetof(struct bpf_insn, imm), 4,
+			       kdesc->insn + offsetof(struct bpf_insn, imm));
+		move_blob2blob(gen, insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm), 4,
+			       kdesc->insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm));
+		/* jump over src_reg adjustment if imm is not 0, reuse BPF_REG_0 from move_blob2blob */
+		emit(gen, BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 3));
+		goto clear_src_reg;
+	}
+	/* remember insn offset, so we can copy BTF ID and FD later */
+	kdesc->insn = insn;
+	emit_bpf_find_by_name_kind(gen, relo);
+	if (!relo->is_weak)
+		emit_check_err(gen);
+	/* jump to success case */
+	emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 3));
+	/* set values for insn[insn_idx].imm, insn[insn_idx + 1].imm as 0 */
+	emit(gen, BPF_ST_MEM(BPF_W, BPF_REG_8, offsetof(struct bpf_insn, imm), 0));
+	emit(gen, BPF_ST_MEM(BPF_W, BPF_REG_8, sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm), 0));
+	/* skip success case for ret < 0 */
+	emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 4));
+	/* store btf_id into insn[insn_idx].imm */
+	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7, offsetof(struct bpf_insn, imm)));
+	/* store btf_obj_fd into insn[insn_idx + 1].imm */
+	emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_7, 32));
+	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7,
+			      sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm)));
+	/* skip src_reg adjustment */
+	emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 3));
+clear_src_reg:
+	/* clear bpf_object__relocate_data's src_reg assignment, otherwise we get a verifier failure */
+	reg_mask = src_reg_mask();
+	emit(gen, BPF_LDX_MEM(BPF_B, BPF_REG_9, BPF_REG_8, offsetofend(struct bpf_insn, code)));
+	emit(gen, BPF_ALU32_IMM(BPF_AND, BPF_REG_9, reg_mask));
+	emit(gen, BPF_STX_MEM(BPF_B, BPF_REG_8, BPF_REG_9, offsetofend(struct bpf_insn, code)));
+
+	emit_ksym_relo_log(gen, relo, kdesc->ref);
+}
+
+void bpf_gen__record_relo_core(struct bpf_gen *gen,
+			       const struct bpf_core_relo *core_relo)
+{
+	struct bpf_core_relo *relos;
+
+	relos = libbpf_reallocarray(gen->core_relos, gen->core_relo_cnt + 1, sizeof(*relos));
+	if (!relos) {
+		gen->error = -ENOMEM;
+		return;
+	}
+	gen->core_relos = relos;
+	relos += gen->core_relo_cnt;
+	memcpy(relos, core_relo, sizeof(*relos));
+	gen->core_relo_cnt++;
+}
+
+static void emit_relo(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insns)
+{
+	int insn;
+
+	pr_debug("gen: emit_relo (%d): %s at %d\n", relo->kind, relo->name, relo->insn_idx);
+	insn = insns + sizeof(struct bpf_insn) * relo->insn_idx;
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_8, BPF_PSEUDO_MAP_IDX_VALUE, 0, 0, 0, insn));
+	switch (relo->kind) {
+	case BTF_KIND_VAR:
+		if (relo->is_typeless)
+			emit_relo_ksym_typeless(gen, relo, insn);
+		else
+			emit_relo_ksym_btf(gen, relo, insn);
+		break;
+	case BTF_KIND_FUNC:
+		emit_relo_kfunc_btf(gen, relo, insn);
+		break;
+	default:
+		pr_warn("Unknown relocation kind '%d'\n", relo->kind);
+		gen->error = -EDOM;
+		return;
+	}
+}
+
+static void emit_relos(struct bpf_gen *gen, int insns)
+{
+	int i;
+
+	for (i = 0; i < gen->relo_cnt; i++)
+		emit_relo(gen, gen->relos + i, insns);
+}
+
+static void cleanup_core_relo(struct bpf_gen *gen)
+{
+	if (!gen->core_relo_cnt)
+		return;
+	free(gen->core_relos);
+	gen->core_relo_cnt = 0;
+	gen->core_relos = NULL;
+}
+
+static void cleanup_relos(struct bpf_gen *gen, int insns)
+{
+	int i, insn;
+
+	for (i = 0; i < gen->nr_ksyms; i++) {
+		/* only close fds for typed ksyms and kfuncs */
+		if (gen->ksyms[i].kind == BTF_KIND_VAR && !gen->ksyms[i].typeless) {
+			/* close fd recorded in insn[insn_idx + 1].imm */
+			insn = gen->ksyms[i].insn;
+			insn += sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm);
+			emit_sys_close_blob(gen, insn);
+		} else if (gen->ksyms[i].kind == BTF_KIND_FUNC) {
+			emit_sys_close_blob(gen, blob_fd_array_off(gen, gen->ksyms[i].off));
+			if (gen->ksyms[i].off < MAX_FD_ARRAY_SZ)
+				gen->nr_fd_array--;
+		}
+	}
+	if (gen->nr_ksyms) {
+		free(gen->ksyms);
+		gen->nr_ksyms = 0;
+		gen->ksyms = NULL;
+	}
+	if (gen->relo_cnt) {
+		free(gen->relos);
+		gen->relo_cnt = 0;
+		gen->relos = NULL;
+	}
+	cleanup_core_relo(gen);
+}
+
+void bpf_gen__prog_load(struct bpf_gen *gen,
+			enum bpf_prog_type prog_type, const char *prog_name,
+			const char *license, struct bpf_insn *insns, size_t insn_cnt,
+			struct bpf_prog_load_opts *load_attr, int prog_idx)
+{
+	int prog_load_attr, license_off, insns_off, func_info, line_info, core_relos;
+	int attr_size = offsetofend(union bpf_attr, core_relo_rec_size);
+	union bpf_attr attr;
+
+	memset(&attr, 0, attr_size);
+	pr_debug("gen: prog_load: type %d insns_cnt %zd progi_idx %d\n",
+		 prog_type, insn_cnt, prog_idx);
+	/* add license string to blob of bytes */
+	license_off = add_data(gen, license, strlen(license) + 1);
+	/* add insns to blob of bytes */
+	insns_off = add_data(gen, insns, insn_cnt * sizeof(struct bpf_insn));
+
+	attr.prog_type = prog_type;
+	attr.expected_attach_type = load_attr->expected_attach_type;
+	attr.attach_btf_id = load_attr->attach_btf_id;
+	attr.prog_ifindex = load_attr->prog_ifindex;
+	attr.kern_version = 0;
+	attr.insn_cnt = (__u32)insn_cnt;
+	attr.prog_flags = load_attr->prog_flags;
+
+	attr.func_info_rec_size = load_attr->func_info_rec_size;
+	attr.func_info_cnt = load_attr->func_info_cnt;
+	func_info = add_data(gen, load_attr->func_info,
+			     attr.func_info_cnt * attr.func_info_rec_size);
+
+	attr.line_info_rec_size = load_attr->line_info_rec_size;
+	attr.line_info_cnt = load_attr->line_info_cnt;
+	line_info = add_data(gen, load_attr->line_info,
+			     attr.line_info_cnt * attr.line_info_rec_size);
+
+	attr.core_relo_rec_size = sizeof(struct bpf_core_relo);
+	attr.core_relo_cnt = gen->core_relo_cnt;
+	core_relos = add_data(gen, gen->core_relos,
+			     attr.core_relo_cnt * attr.core_relo_rec_size);
+
+	libbpf_strlcpy(attr.prog_name, prog_name, sizeof(attr.prog_name));
+	prog_load_attr = add_data(gen, &attr, attr_size);
+
+	/* populate union bpf_attr with a pointer to license */
+	emit_rel_store(gen, attr_field(prog_load_attr, license), license_off);
+
+	/* populate union bpf_attr with a pointer to instructions */
+	emit_rel_store(gen, attr_field(prog_load_attr, insns), insns_off);
+
+	/* populate union bpf_attr with a pointer to func_info */
+	emit_rel_store(gen, attr_field(prog_load_attr, func_info), func_info);
+
+	/* populate union bpf_attr with a pointer to line_info */
+	emit_rel_store(gen, attr_field(prog_load_attr, line_info), line_info);
+
+	/* populate union bpf_attr with a pointer to core_relos */
+	emit_rel_store(gen, attr_field(prog_load_attr, core_relos), core_relos);
+
+	/* populate union bpf_attr fd_array with a pointer to data where map_fds are saved */
+	emit_rel_store(gen, attr_field(prog_load_attr, fd_array), gen->fd_array);
+
+	/* populate union bpf_attr with user provided log details */
+	move_ctx2blob(gen, attr_field(prog_load_attr, log_level), 4,
+		      offsetof(struct bpf_loader_ctx, log_level), false);
+	move_ctx2blob(gen, attr_field(prog_load_attr, log_size), 4,
+		      offsetof(struct bpf_loader_ctx, log_size), false);
+	move_ctx2blob(gen, attr_field(prog_load_attr, log_buf), 8,
+		      offsetof(struct bpf_loader_ctx, log_buf), false);
+	/* populate union bpf_attr with btf_fd saved in the stack earlier */
+	move_stack2blob(gen, attr_field(prog_load_attr, prog_btf_fd), 4,
+			stack_off(btf_fd));
+	if (gen->attach_kind) {
+		emit_find_attach_target(gen);
+		/* populate union bpf_attr with btf_id and btf_obj_fd found by helper */
+		emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
+						 0, 0, 0, prog_load_attr));
+		emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_7,
+				      offsetof(union bpf_attr, attach_btf_id)));
+		emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_7, 32));
+		emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_7,
+				      offsetof(union bpf_attr, attach_btf_obj_fd)));
+	}
+	emit_relos(gen, insns_off);
+	/* emit PROG_LOAD command */
+	emit_sys_bpf(gen, BPF_PROG_LOAD, prog_load_attr, attr_size);
+	debug_ret(gen, "prog_load %s insn_cnt %d", attr.prog_name, attr.insn_cnt);
+	/* successful or not, close btf module FDs used in extern ksyms and attach_btf_obj_fd */
+	cleanup_relos(gen, insns_off);
+	if (gen->attach_kind) {
+		emit_sys_close_blob(gen,
+				    attr_field(prog_load_attr, attach_btf_obj_fd));
+		gen->attach_kind = 0;
+	}
+	emit_check_err(gen);
+	/* remember prog_fd in the stack, if successful */
+	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_7,
+			      stack_off(prog_fd[gen->nr_progs])));
+	gen->nr_progs++;
+}
+
+void bpf_gen__map_update_elem(struct bpf_gen *gen, int map_idx, void *pvalue,
+			      __u32 value_size)
+{
+	int attr_size = offsetofend(union bpf_attr, flags);
+	int map_update_attr, value, key;
+	union bpf_attr attr;
+	int zero = 0;
+
+	memset(&attr, 0, attr_size);
+	pr_debug("gen: map_update_elem: idx %d\n", map_idx);
+
+	value = add_data(gen, pvalue, value_size);
+	key = add_data(gen, &zero, sizeof(zero));
+
+	/* if (map_desc[map_idx].initial_value) {
+	 *    if (ctx->flags & BPF_SKEL_KERNEL)
+	 *        bpf_probe_read_kernel(value, value_size, initial_value);
+	 *    else
+	 *        bpf_copy_from_user(value, value_size, initial_value);
+	 * }
+	 */
+	emit(gen, BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_6,
+			      sizeof(struct bpf_loader_ctx) +
+			      sizeof(struct bpf_map_desc) * map_idx +
+			      offsetof(struct bpf_map_desc, initial_value)));
+	emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_3, 0, 8));
+	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+					 0, 0, 0, value));
+	emit(gen, BPF_MOV64_IMM(BPF_REG_2, value_size));
+	emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6,
+			      offsetof(struct bpf_loader_ctx, flags)));
+	emit(gen, BPF_JMP_IMM(BPF_JSET, BPF_REG_0, BPF_SKEL_KERNEL, 2));
+	emit(gen, BPF_EMIT_CALL(BPF_FUNC_copy_from_user));
+	emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 1));
+	emit(gen, BPF_EMIT_CALL(BPF_FUNC_probe_read_kernel));
+
+	map_update_attr = add_data(gen, &attr, attr_size);
+	move_blob2blob(gen, attr_field(map_update_attr, map_fd), 4,
+		       blob_fd_array_off(gen, map_idx));
+	emit_rel_store(gen, attr_field(map_update_attr, key), key);
+	emit_rel_store(gen, attr_field(map_update_attr, value), value);
+	/* emit MAP_UPDATE_ELEM command */
+	emit_sys_bpf(gen, BPF_MAP_UPDATE_ELEM, map_update_attr, attr_size);
+	debug_ret(gen, "update_elem idx %d value_size %d", map_idx, value_size);
+	emit_check_err(gen);
+}
+
+void bpf_gen__populate_outer_map(struct bpf_gen *gen, int outer_map_idx, int slot,
+				 int inner_map_idx)
+{
+	int attr_size = offsetofend(union bpf_attr, flags);
+	int map_update_attr, key;
+	union bpf_attr attr;
+
+	memset(&attr, 0, attr_size);
+	pr_debug("gen: populate_outer_map: outer %d key %d inner %d\n",
+		 outer_map_idx, slot, inner_map_idx);
+
+	key = add_data(gen, &slot, sizeof(slot));
+
+	map_update_attr = add_data(gen, &attr, attr_size);
+	move_blob2blob(gen, attr_field(map_update_attr, map_fd), 4,
+		       blob_fd_array_off(gen, outer_map_idx));
+	emit_rel_store(gen, attr_field(map_update_attr, key), key);
+	emit_rel_store(gen, attr_field(map_update_attr, value),
+		       blob_fd_array_off(gen, inner_map_idx));
+
+	/* emit MAP_UPDATE_ELEM command */
+	emit_sys_bpf(gen, BPF_MAP_UPDATE_ELEM, map_update_attr, attr_size);
+	debug_ret(gen, "populate_outer_map outer %d key %d inner %d",
+		  outer_map_idx, slot, inner_map_idx);
+	emit_check_err(gen);
+}
+
+void bpf_gen__map_freeze(struct bpf_gen *gen, int map_idx)
+{
+	int attr_size = offsetofend(union bpf_attr, map_fd);
+	int map_freeze_attr;
+	union bpf_attr attr;
+
+	memset(&attr, 0, attr_size);
+	pr_debug("gen: map_freeze: idx %d\n", map_idx);
+	map_freeze_attr = add_data(gen, &attr, attr_size);
+	move_blob2blob(gen, attr_field(map_freeze_attr, map_fd), 4,
+		       blob_fd_array_off(gen, map_idx));
+	/* emit MAP_FREEZE command */
+	emit_sys_bpf(gen, BPF_MAP_FREEZE, map_freeze_attr, attr_size);
+	debug_ret(gen, "map_freeze");
+	emit_check_err(gen);
+}
diff --git a/src/hashmap.c b/src/hashmap.c
new file mode 100644
index 0000000..140ee40
--- /dev/null
+++ b/src/hashmap.c
@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * Generic non-thread safe hash map implementation.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <linux/err.h>
+#include "hashmap.h"
+
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
+/* prevent accidental re-addition of reallocarray() */
+#pragma GCC poison reallocarray
+
+/* start with 4 buckets */
+#define HASHMAP_MIN_CAP_BITS 2
+
+static void hashmap_add_entry(struct hashmap_entry **pprev,
+			      struct hashmap_entry *entry)
+{
+	entry->next = *pprev;
+	*pprev = entry;
+}
+
+static void hashmap_del_entry(struct hashmap_entry **pprev,
+			      struct hashmap_entry *entry)
+{
+	*pprev = entry->next;
+	entry->next = NULL;
+}
+
+void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
+		   hashmap_equal_fn equal_fn, void *ctx)
+{
+	map->hash_fn = hash_fn;
+	map->equal_fn = equal_fn;
+	map->ctx = ctx;
+
+	map->buckets = NULL;
+	map->cap = 0;
+	map->cap_bits = 0;
+	map->sz = 0;
+}
+
+struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
+			     hashmap_equal_fn equal_fn,
+			     void *ctx)
+{
+	struct hashmap *map = malloc(sizeof(struct hashmap));
+
+	if (!map)
+		return ERR_PTR(-ENOMEM);
+	hashmap__init(map, hash_fn, equal_fn, ctx);
+	return map;
+}
+
+void hashmap__clear(struct hashmap *map)
+{
+	struct hashmap_entry *cur, *tmp;
+	size_t bkt;
+
+	hashmap__for_each_entry_safe(map, cur, tmp, bkt) {
+		free(cur);
+	}
+	free(map->buckets);
+	map->buckets = NULL;
+	map->cap = map->cap_bits = map->sz = 0;
+}
+
+void hashmap__free(struct hashmap *map)
+{
+	if (IS_ERR_OR_NULL(map))
+		return;
+
+	hashmap__clear(map);
+	free(map);
+}
+
+size_t hashmap__size(const struct hashmap *map)
+{
+	return map->sz;
+}
+
+size_t hashmap__capacity(const struct hashmap *map)
+{
+	return map->cap;
+}
+
+static bool hashmap_needs_to_grow(struct hashmap *map)
+{
+	/* grow if empty or more than 75% filled */
+	return (map->cap == 0) || ((map->sz + 1) * 4 / 3 > map->cap);
+}
+
+static int hashmap_grow(struct hashmap *map)
+{
+	struct hashmap_entry **new_buckets;
+	struct hashmap_entry *cur, *tmp;
+	size_t new_cap_bits, new_cap;
+	size_t h, bkt;
+
+	new_cap_bits = map->cap_bits + 1;
+	if (new_cap_bits < HASHMAP_MIN_CAP_BITS)
+		new_cap_bits = HASHMAP_MIN_CAP_BITS;
+
+	new_cap = 1UL << new_cap_bits;
+	new_buckets = calloc(new_cap, sizeof(new_buckets[0]));
+	if (!new_buckets)
+		return -ENOMEM;
+
+	hashmap__for_each_entry_safe(map, cur, tmp, bkt) {
+		h = hash_bits(map->hash_fn(cur->key, map->ctx), new_cap_bits);
+		hashmap_add_entry(&new_buckets[h], cur);
+	}
+
+	map->cap = new_cap;
+	map->cap_bits = new_cap_bits;
+	free(map->buckets);
+	map->buckets = new_buckets;
+
+	return 0;
+}
+
+static bool hashmap_find_entry(const struct hashmap *map,
+			       const long key, size_t hash,
+			       struct hashmap_entry ***pprev,
+			       struct hashmap_entry **entry)
+{
+	struct hashmap_entry *cur, **prev_ptr;
+
+	if (!map->buckets)
+		return false;
+
+	for (prev_ptr = &map->buckets[hash], cur = *prev_ptr;
+	     cur;
+	     prev_ptr = &cur->next, cur = cur->next) {
+		if (map->equal_fn(cur->key, key, map->ctx)) {
+			if (pprev)
+				*pprev = prev_ptr;
+			*entry = cur;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+int hashmap_insert(struct hashmap *map, long key, long value,
+		   enum hashmap_insert_strategy strategy,
+		   long *old_key, long *old_value)
+{
+	struct hashmap_entry *entry;
+	size_t h;
+	int err;
+
+	if (old_key)
+		*old_key = 0;
+	if (old_value)
+		*old_value = 0;
+
+	h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+	if (strategy != HASHMAP_APPEND &&
+	    hashmap_find_entry(map, key, h, NULL, &entry)) {
+		if (old_key)
+			*old_key = entry->key;
+		if (old_value)
+			*old_value = entry->value;
+
+		if (strategy == HASHMAP_SET || strategy == HASHMAP_UPDATE) {
+			entry->key = key;
+			entry->value = value;
+			return 0;
+		} else if (strategy == HASHMAP_ADD) {
+			return -EEXIST;
+		}
+	}
+
+	if (strategy == HASHMAP_UPDATE)
+		return -ENOENT;
+
+	if (hashmap_needs_to_grow(map)) {
+		err = hashmap_grow(map);
+		if (err)
+			return err;
+		h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+	}
+
+	entry = malloc(sizeof(struct hashmap_entry));
+	if (!entry)
+		return -ENOMEM;
+
+	entry->key = key;
+	entry->value = value;
+	hashmap_add_entry(&map->buckets[h], entry);
+	map->sz++;
+
+	return 0;
+}
+
+bool hashmap_find(const struct hashmap *map, long key, long *value)
+{
+	struct hashmap_entry *entry;
+	size_t h;
+
+	h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+	if (!hashmap_find_entry(map, key, h, NULL, &entry))
+		return false;
+
+	if (value)
+		*value = entry->value;
+	return true;
+}
+
+bool hashmap_delete(struct hashmap *map, long key,
+		    long *old_key, long *old_value)
+{
+	struct hashmap_entry **pprev, *entry;
+	size_t h;
+
+	h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+	if (!hashmap_find_entry(map, key, h, &pprev, &entry))
+		return false;
+
+	if (old_key)
+		*old_key = entry->key;
+	if (old_value)
+		*old_value = entry->value;
+
+	hashmap_del_entry(pprev, entry);
+	free(entry);
+	map->sz--;
+
+	return true;
+}
diff --git a/src/hashmap.h b/src/hashmap.h
new file mode 100644
index 0000000..0a5bf19
--- /dev/null
+++ b/src/hashmap.h
@@ -0,0 +1,218 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Generic non-thread safe hash map implementation.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+#ifndef __LIBBPF_HASHMAP_H
+#define __LIBBPF_HASHMAP_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <limits.h>
+
+static inline size_t hash_bits(size_t h, int bits)
+{
+	/* shuffle bits and return requested number of upper bits */
+	if (bits == 0)
+		return 0;
+
+#if (__SIZEOF_SIZE_T__ == __SIZEOF_LONG_LONG__)
+	/* LP64 case */
+	return (h * 11400714819323198485llu) >> (__SIZEOF_LONG_LONG__ * 8 - bits);
+#elif (__SIZEOF_SIZE_T__ <= __SIZEOF_LONG__)
+	return (h * 2654435769lu) >> (__SIZEOF_LONG__ * 8 - bits);
+#else
+#	error "Unsupported size_t size"
+#endif
+}
+
+/* generic C-string hashing function */
+static inline size_t str_hash(const char *s)
+{
+	size_t h = 0;
+
+	while (*s) {
+		h = h * 31 + *s;
+		s++;
+	}
+	return h;
+}
+
+typedef size_t (*hashmap_hash_fn)(long key, void *ctx);
+typedef bool (*hashmap_equal_fn)(long key1, long key2, void *ctx);
+
+/*
+ * Hashmap interface is polymorphic, keys and values could be either
+ * long-sized integers or pointers, this is achieved as follows:
+ * - interface functions that operate on keys and values are hidden
+ *   behind auxiliary macros, e.g. hashmap_insert <-> hashmap__insert;
+ * - these auxiliary macros cast the key and value parameters as
+ *   long or long *, so the user does not have to specify the casts explicitly;
+ * - for pointer parameters (e.g. old_key) the size of the pointed
+ *   type is verified by hashmap_cast_ptr using _Static_assert;
+ * - when iterating using hashmap__for_each_* forms
+ *   hasmap_entry->key should be used for integer keys and
+ *   hasmap_entry->pkey should be used for pointer keys,
+ *   same goes for values.
+ */
+struct hashmap_entry {
+	union {
+		long key;
+		const void *pkey;
+	};
+	union {
+		long value;
+		void *pvalue;
+	};
+	struct hashmap_entry *next;
+};
+
+struct hashmap {
+	hashmap_hash_fn hash_fn;
+	hashmap_equal_fn equal_fn;
+	void *ctx;
+
+	struct hashmap_entry **buckets;
+	size_t cap;
+	size_t cap_bits;
+	size_t sz;
+};
+
+#define HASHMAP_INIT(hash_fn, equal_fn, ctx) {	\
+	.hash_fn = (hash_fn),			\
+	.equal_fn = (equal_fn),			\
+	.ctx = (ctx),				\
+	.buckets = NULL,			\
+	.cap = 0,				\
+	.cap_bits = 0,				\
+	.sz = 0,				\
+}
+
+void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
+		   hashmap_equal_fn equal_fn, void *ctx);
+struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
+			     hashmap_equal_fn equal_fn,
+			     void *ctx);
+void hashmap__clear(struct hashmap *map);
+void hashmap__free(struct hashmap *map);
+
+size_t hashmap__size(const struct hashmap *map);
+size_t hashmap__capacity(const struct hashmap *map);
+
+/*
+ * Hashmap insertion strategy:
+ * - HASHMAP_ADD - only add key/value if key doesn't exist yet;
+ * - HASHMAP_SET - add key/value pair if key doesn't exist yet; otherwise,
+ *   update value;
+ * - HASHMAP_UPDATE - update value, if key already exists; otherwise, do
+ *   nothing and return -ENOENT;
+ * - HASHMAP_APPEND - always add key/value pair, even if key already exists.
+ *   This turns hashmap into a multimap by allowing multiple values to be
+ *   associated with the same key. Most useful read API for such hashmap is
+ *   hashmap__for_each_key_entry() iteration. If hashmap__find() is still
+ *   used, it will return last inserted key/value entry (first in a bucket
+ *   chain).
+ */
+enum hashmap_insert_strategy {
+	HASHMAP_ADD,
+	HASHMAP_SET,
+	HASHMAP_UPDATE,
+	HASHMAP_APPEND,
+};
+
+#define hashmap_cast_ptr(p) ({								\
+	_Static_assert((__builtin_constant_p((p)) ? (p) == NULL : 0) ||			\
+				sizeof(*(p)) == sizeof(long),				\
+		       #p " pointee should be a long-sized integer or a pointer");	\
+	(long *)(p);									\
+})
+
+/*
+ * hashmap__insert() adds key/value entry w/ various semantics, depending on
+ * provided strategy value. If a given key/value pair replaced already
+ * existing key/value pair, both old key and old value will be returned
+ * through old_key and old_value to allow calling code do proper memory
+ * management.
+ */
+int hashmap_insert(struct hashmap *map, long key, long value,
+		   enum hashmap_insert_strategy strategy,
+		   long *old_key, long *old_value);
+
+#define hashmap__insert(map, key, value, strategy, old_key, old_value) \
+	hashmap_insert((map), (long)(key), (long)(value), (strategy),  \
+		       hashmap_cast_ptr(old_key),		       \
+		       hashmap_cast_ptr(old_value))
+
+#define hashmap__add(map, key, value) \
+	hashmap__insert((map), (key), (value), HASHMAP_ADD, NULL, NULL)
+
+#define hashmap__set(map, key, value, old_key, old_value) \
+	hashmap__insert((map), (key), (value), HASHMAP_SET, (old_key), (old_value))
+
+#define hashmap__update(map, key, value, old_key, old_value) \
+	hashmap__insert((map), (key), (value), HASHMAP_UPDATE, (old_key), (old_value))
+
+#define hashmap__append(map, key, value) \
+	hashmap__insert((map), (key), (value), HASHMAP_APPEND, NULL, NULL)
+
+bool hashmap_delete(struct hashmap *map, long key, long *old_key, long *old_value);
+
+#define hashmap__delete(map, key, old_key, old_value)		       \
+	hashmap_delete((map), (long)(key),			       \
+		       hashmap_cast_ptr(old_key),		       \
+		       hashmap_cast_ptr(old_value))
+
+bool hashmap_find(const struct hashmap *map, long key, long *value);
+
+#define hashmap__find(map, key, value) \
+	hashmap_find((map), (long)(key), hashmap_cast_ptr(value))
+
+/*
+ * hashmap__for_each_entry - iterate over all entries in hashmap
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @bkt: integer used as a bucket loop cursor
+ */
+#define hashmap__for_each_entry(map, cur, bkt)				    \
+	for (bkt = 0; bkt < map->cap; bkt++)				    \
+		for (cur = map->buckets[bkt]; cur; cur = cur->next)
+
+/*
+ * hashmap__for_each_entry_safe - iterate over all entries in hashmap, safe
+ * against removals
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @tmp: struct hashmap_entry * used as a temporary next cursor storage
+ * @bkt: integer used as a bucket loop cursor
+ */
+#define hashmap__for_each_entry_safe(map, cur, tmp, bkt)		    \
+	for (bkt = 0; bkt < map->cap; bkt++)				    \
+		for (cur = map->buckets[bkt];				    \
+		     cur && ({tmp = cur->next; true; });		    \
+		     cur = tmp)
+
+/*
+ * hashmap__for_each_key_entry - iterate over entries associated with given key
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @key: key to iterate entries for
+ */
+#define hashmap__for_each_key_entry(map, cur, _key)			    \
+	for (cur = map->buckets						    \
+		     ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
+		     : NULL;						    \
+	     cur;							    \
+	     cur = cur->next)						    \
+		if (map->equal_fn(cur->key, (_key), map->ctx))
+
+#define hashmap__for_each_key_entry_safe(map, cur, tmp, _key)		    \
+	for (cur = map->buckets						    \
+		     ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
+		     : NULL;						    \
+	     cur && ({ tmp = cur->next; true; });			    \
+	     cur = tmp)							    \
+		if (map->equal_fn(cur->key, (_key), map->ctx))
+
+#endif /* __LIBBPF_HASHMAP_H */
diff --git a/src/libbpf.c b/src/libbpf.c
new file mode 100644
index 0000000..a5c67a3
--- /dev/null
+++ b/src/libbpf.c
@@ -0,0 +1,12490 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * Common eBPF ELF object loading operations.
+ *
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ * Copyright (C) 2017 Nicira, Inc.
+ * Copyright (C) 2019 Isovalent, Inc.
+ */
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <libgen.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <string.h>
+#include <unistd.h>
+#include <endian.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <ctype.h>
+#include <asm/unistd.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/filter.h>
+#include <linux/limits.h>
+#include <linux/perf_event.h>
+#include <linux/ring_buffer.h>
+#include <linux/version.h>
+#include <sys/epoll.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/vfs.h>
+#include <sys/utsname.h>
+#include <sys/resource.h>
+#include <libelf.h>
+#include <gelf.h>
+#include <zlib.h>
+
+#include "libbpf.h"
+#include "bpf.h"
+#include "btf.h"
+#include "str_error.h"
+#include "libbpf_internal.h"
+#include "hashmap.h"
+#include "bpf_gen_internal.h"
+
+#ifndef BPF_FS_MAGIC
+#define BPF_FS_MAGIC		0xcafe4a11
+#endif
+
+#define BPF_INSN_SZ (sizeof(struct bpf_insn))
+
+/* vsprintf() in __base_pr() uses nonliteral format string. It may break
+ * compilation if user enables corresponding warning. Disable it explicitly.
+ */
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
+
+#define __printf(a, b)	__attribute__((format(printf, a, b)))
+
+static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
+static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
+
+static const char * const attach_type_name[] = {
+	[BPF_CGROUP_INET_INGRESS]	= "cgroup_inet_ingress",
+	[BPF_CGROUP_INET_EGRESS]	= "cgroup_inet_egress",
+	[BPF_CGROUP_INET_SOCK_CREATE]	= "cgroup_inet_sock_create",
+	[BPF_CGROUP_INET_SOCK_RELEASE]	= "cgroup_inet_sock_release",
+	[BPF_CGROUP_SOCK_OPS]		= "cgroup_sock_ops",
+	[BPF_CGROUP_DEVICE]		= "cgroup_device",
+	[BPF_CGROUP_INET4_BIND]		= "cgroup_inet4_bind",
+	[BPF_CGROUP_INET6_BIND]		= "cgroup_inet6_bind",
+	[BPF_CGROUP_INET4_CONNECT]	= "cgroup_inet4_connect",
+	[BPF_CGROUP_INET6_CONNECT]	= "cgroup_inet6_connect",
+	[BPF_CGROUP_INET4_POST_BIND]	= "cgroup_inet4_post_bind",
+	[BPF_CGROUP_INET6_POST_BIND]	= "cgroup_inet6_post_bind",
+	[BPF_CGROUP_INET4_GETPEERNAME]	= "cgroup_inet4_getpeername",
+	[BPF_CGROUP_INET6_GETPEERNAME]	= "cgroup_inet6_getpeername",
+	[BPF_CGROUP_INET4_GETSOCKNAME]	= "cgroup_inet4_getsockname",
+	[BPF_CGROUP_INET6_GETSOCKNAME]	= "cgroup_inet6_getsockname",
+	[BPF_CGROUP_UDP4_SENDMSG]	= "cgroup_udp4_sendmsg",
+	[BPF_CGROUP_UDP6_SENDMSG]	= "cgroup_udp6_sendmsg",
+	[BPF_CGROUP_SYSCTL]		= "cgroup_sysctl",
+	[BPF_CGROUP_UDP4_RECVMSG]	= "cgroup_udp4_recvmsg",
+	[BPF_CGROUP_UDP6_RECVMSG]	= "cgroup_udp6_recvmsg",
+	[BPF_CGROUP_GETSOCKOPT]		= "cgroup_getsockopt",
+	[BPF_CGROUP_SETSOCKOPT]		= "cgroup_setsockopt",
+	[BPF_SK_SKB_STREAM_PARSER]	= "sk_skb_stream_parser",
+	[BPF_SK_SKB_STREAM_VERDICT]	= "sk_skb_stream_verdict",
+	[BPF_SK_SKB_VERDICT]		= "sk_skb_verdict",
+	[BPF_SK_MSG_VERDICT]		= "sk_msg_verdict",
+	[BPF_LIRC_MODE2]		= "lirc_mode2",
+	[BPF_FLOW_DISSECTOR]		= "flow_dissector",
+	[BPF_TRACE_RAW_TP]		= "trace_raw_tp",
+	[BPF_TRACE_FENTRY]		= "trace_fentry",
+	[BPF_TRACE_FEXIT]		= "trace_fexit",
+	[BPF_MODIFY_RETURN]		= "modify_return",
+	[BPF_LSM_MAC]			= "lsm_mac",
+	[BPF_LSM_CGROUP]		= "lsm_cgroup",
+	[BPF_SK_LOOKUP]			= "sk_lookup",
+	[BPF_TRACE_ITER]		= "trace_iter",
+	[BPF_XDP_DEVMAP]		= "xdp_devmap",
+	[BPF_XDP_CPUMAP]		= "xdp_cpumap",
+	[BPF_XDP]			= "xdp",
+	[BPF_SK_REUSEPORT_SELECT]	= "sk_reuseport_select",
+	[BPF_SK_REUSEPORT_SELECT_OR_MIGRATE]	= "sk_reuseport_select_or_migrate",
+	[BPF_PERF_EVENT]		= "perf_event",
+	[BPF_TRACE_KPROBE_MULTI]	= "trace_kprobe_multi",
+};
+
+static const char * const link_type_name[] = {
+	[BPF_LINK_TYPE_UNSPEC]			= "unspec",
+	[BPF_LINK_TYPE_RAW_TRACEPOINT]		= "raw_tracepoint",
+	[BPF_LINK_TYPE_TRACING]			= "tracing",
+	[BPF_LINK_TYPE_CGROUP]			= "cgroup",
+	[BPF_LINK_TYPE_ITER]			= "iter",
+	[BPF_LINK_TYPE_NETNS]			= "netns",
+	[BPF_LINK_TYPE_XDP]			= "xdp",
+	[BPF_LINK_TYPE_PERF_EVENT]		= "perf_event",
+	[BPF_LINK_TYPE_KPROBE_MULTI]		= "kprobe_multi",
+	[BPF_LINK_TYPE_STRUCT_OPS]		= "struct_ops",
+};
+
+static const char * const map_type_name[] = {
+	[BPF_MAP_TYPE_UNSPEC]			= "unspec",
+	[BPF_MAP_TYPE_HASH]			= "hash",
+	[BPF_MAP_TYPE_ARRAY]			= "array",
+	[BPF_MAP_TYPE_PROG_ARRAY]		= "prog_array",
+	[BPF_MAP_TYPE_PERF_EVENT_ARRAY]		= "perf_event_array",
+	[BPF_MAP_TYPE_PERCPU_HASH]		= "percpu_hash",
+	[BPF_MAP_TYPE_PERCPU_ARRAY]		= "percpu_array",
+	[BPF_MAP_TYPE_STACK_TRACE]		= "stack_trace",
+	[BPF_MAP_TYPE_CGROUP_ARRAY]		= "cgroup_array",
+	[BPF_MAP_TYPE_LRU_HASH]			= "lru_hash",
+	[BPF_MAP_TYPE_LRU_PERCPU_HASH]		= "lru_percpu_hash",
+	[BPF_MAP_TYPE_LPM_TRIE]			= "lpm_trie",
+	[BPF_MAP_TYPE_ARRAY_OF_MAPS]		= "array_of_maps",
+	[BPF_MAP_TYPE_HASH_OF_MAPS]		= "hash_of_maps",
+	[BPF_MAP_TYPE_DEVMAP]			= "devmap",
+	[BPF_MAP_TYPE_DEVMAP_HASH]		= "devmap_hash",
+	[BPF_MAP_TYPE_SOCKMAP]			= "sockmap",
+	[BPF_MAP_TYPE_CPUMAP]			= "cpumap",
+	[BPF_MAP_TYPE_XSKMAP]			= "xskmap",
+	[BPF_MAP_TYPE_SOCKHASH]			= "sockhash",
+	[BPF_MAP_TYPE_CGROUP_STORAGE]		= "cgroup_storage",
+	[BPF_MAP_TYPE_REUSEPORT_SOCKARRAY]	= "reuseport_sockarray",
+	[BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE]	= "percpu_cgroup_storage",
+	[BPF_MAP_TYPE_QUEUE]			= "queue",
+	[BPF_MAP_TYPE_STACK]			= "stack",
+	[BPF_MAP_TYPE_SK_STORAGE]		= "sk_storage",
+	[BPF_MAP_TYPE_STRUCT_OPS]		= "struct_ops",
+	[BPF_MAP_TYPE_RINGBUF]			= "ringbuf",
+	[BPF_MAP_TYPE_INODE_STORAGE]		= "inode_storage",
+	[BPF_MAP_TYPE_TASK_STORAGE]		= "task_storage",
+	[BPF_MAP_TYPE_BLOOM_FILTER]		= "bloom_filter",
+	[BPF_MAP_TYPE_USER_RINGBUF]             = "user_ringbuf",
+	[BPF_MAP_TYPE_CGRP_STORAGE]		= "cgrp_storage",
+};
+
+static const char * const prog_type_name[] = {
+	[BPF_PROG_TYPE_UNSPEC]			= "unspec",
+	[BPF_PROG_TYPE_SOCKET_FILTER]		= "socket_filter",
+	[BPF_PROG_TYPE_KPROBE]			= "kprobe",
+	[BPF_PROG_TYPE_SCHED_CLS]		= "sched_cls",
+	[BPF_PROG_TYPE_SCHED_ACT]		= "sched_act",
+	[BPF_PROG_TYPE_TRACEPOINT]		= "tracepoint",
+	[BPF_PROG_TYPE_XDP]			= "xdp",
+	[BPF_PROG_TYPE_PERF_EVENT]		= "perf_event",
+	[BPF_PROG_TYPE_CGROUP_SKB]		= "cgroup_skb",
+	[BPF_PROG_TYPE_CGROUP_SOCK]		= "cgroup_sock",
+	[BPF_PROG_TYPE_LWT_IN]			= "lwt_in",
+	[BPF_PROG_TYPE_LWT_OUT]			= "lwt_out",
+	[BPF_PROG_TYPE_LWT_XMIT]		= "lwt_xmit",
+	[BPF_PROG_TYPE_SOCK_OPS]		= "sock_ops",
+	[BPF_PROG_TYPE_SK_SKB]			= "sk_skb",
+	[BPF_PROG_TYPE_CGROUP_DEVICE]		= "cgroup_device",
+	[BPF_PROG_TYPE_SK_MSG]			= "sk_msg",
+	[BPF_PROG_TYPE_RAW_TRACEPOINT]		= "raw_tracepoint",
+	[BPF_PROG_TYPE_CGROUP_SOCK_ADDR]	= "cgroup_sock_addr",
+	[BPF_PROG_TYPE_LWT_SEG6LOCAL]		= "lwt_seg6local",
+	[BPF_PROG_TYPE_LIRC_MODE2]		= "lirc_mode2",
+	[BPF_PROG_TYPE_SK_REUSEPORT]		= "sk_reuseport",
+	[BPF_PROG_TYPE_FLOW_DISSECTOR]		= "flow_dissector",
+	[BPF_PROG_TYPE_CGROUP_SYSCTL]		= "cgroup_sysctl",
+	[BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE]	= "raw_tracepoint_writable",
+	[BPF_PROG_TYPE_CGROUP_SOCKOPT]		= "cgroup_sockopt",
+	[BPF_PROG_TYPE_TRACING]			= "tracing",
+	[BPF_PROG_TYPE_STRUCT_OPS]		= "struct_ops",
+	[BPF_PROG_TYPE_EXT]			= "ext",
+	[BPF_PROG_TYPE_LSM]			= "lsm",
+	[BPF_PROG_TYPE_SK_LOOKUP]		= "sk_lookup",
+	[BPF_PROG_TYPE_SYSCALL]			= "syscall",
+};
+
+static int __base_pr(enum libbpf_print_level level, const char *format,
+		     va_list args)
+{
+	if (level == LIBBPF_DEBUG)
+		return 0;
+
+	return vfprintf(stderr, format, args);
+}
+
+static libbpf_print_fn_t __libbpf_pr = __base_pr;
+
+libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn)
+{
+	libbpf_print_fn_t old_print_fn = __libbpf_pr;
+
+	__libbpf_pr = fn;
+	return old_print_fn;
+}
+
+__printf(2, 3)
+void libbpf_print(enum libbpf_print_level level, const char *format, ...)
+{
+	va_list args;
+	int old_errno;
+
+	if (!__libbpf_pr)
+		return;
+
+	old_errno = errno;
+
+	va_start(args, format);
+	__libbpf_pr(level, format, args);
+	va_end(args);
+
+	errno = old_errno;
+}
+
+static void pr_perm_msg(int err)
+{
+	struct rlimit limit;
+	char buf[100];
+
+	if (err != -EPERM || geteuid() != 0)
+		return;
+
+	err = getrlimit(RLIMIT_MEMLOCK, &limit);
+	if (err)
+		return;
+
+	if (limit.rlim_cur == RLIM_INFINITY)
+		return;
+
+	if (limit.rlim_cur < 1024)
+		snprintf(buf, sizeof(buf), "%zu bytes", (size_t)limit.rlim_cur);
+	else if (limit.rlim_cur < 1024*1024)
+		snprintf(buf, sizeof(buf), "%.1f KiB", (double)limit.rlim_cur / 1024);
+	else
+		snprintf(buf, sizeof(buf), "%.1f MiB", (double)limit.rlim_cur / (1024*1024));
+
+	pr_warn("permission error while running as root; try raising 'ulimit -l'? current value: %s\n",
+		buf);
+}
+
+#define STRERR_BUFSIZE  128
+
+/* Copied from tools/perf/util/util.h */
+#ifndef zfree
+# define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
+#endif
+
+#ifndef zclose
+# define zclose(fd) ({			\
+	int ___err = 0;			\
+	if ((fd) >= 0)			\
+		___err = close((fd));	\
+	fd = -1;			\
+	___err; })
+#endif
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64) (unsigned long) ptr;
+}
+
+int libbpf_set_strict_mode(enum libbpf_strict_mode mode)
+{
+	/* as of v1.0 libbpf_set_strict_mode() is a no-op */
+	return 0;
+}
+
+__u32 libbpf_major_version(void)
+{
+	return LIBBPF_MAJOR_VERSION;
+}
+
+__u32 libbpf_minor_version(void)
+{
+	return LIBBPF_MINOR_VERSION;
+}
+
+const char *libbpf_version_string(void)
+{
+#define __S(X) #X
+#define _S(X) __S(X)
+	return  "v" _S(LIBBPF_MAJOR_VERSION) "." _S(LIBBPF_MINOR_VERSION);
+#undef _S
+#undef __S
+}
+
+enum reloc_type {
+	RELO_LD64,
+	RELO_CALL,
+	RELO_DATA,
+	RELO_EXTERN_VAR,
+	RELO_EXTERN_FUNC,
+	RELO_SUBPROG_ADDR,
+	RELO_CORE,
+};
+
+struct reloc_desc {
+	enum reloc_type type;
+	int insn_idx;
+	union {
+		const struct bpf_core_relo *core_relo; /* used when type == RELO_CORE */
+		struct {
+			int map_idx;
+			int sym_off;
+		};
+	};
+};
+
+/* stored as sec_def->cookie for all libbpf-supported SEC()s */
+enum sec_def_flags {
+	SEC_NONE = 0,
+	/* expected_attach_type is optional, if kernel doesn't support that */
+	SEC_EXP_ATTACH_OPT = 1,
+	/* legacy, only used by libbpf_get_type_names() and
+	 * libbpf_attach_type_by_name(), not used by libbpf itself at all.
+	 * This used to be associated with cgroup (and few other) BPF programs
+	 * that were attachable through BPF_PROG_ATTACH command. Pretty
+	 * meaningless nowadays, though.
+	 */
+	SEC_ATTACHABLE = 2,
+	SEC_ATTACHABLE_OPT = SEC_ATTACHABLE | SEC_EXP_ATTACH_OPT,
+	/* attachment target is specified through BTF ID in either kernel or
+	 * other BPF program's BTF object
+	 */
+	SEC_ATTACH_BTF = 4,
+	/* BPF program type allows sleeping/blocking in kernel */
+	SEC_SLEEPABLE = 8,
+	/* BPF program support non-linear XDP buffer */
+	SEC_XDP_FRAGS = 16,
+};
+
+struct bpf_sec_def {
+	char *sec;
+	enum bpf_prog_type prog_type;
+	enum bpf_attach_type expected_attach_type;
+	long cookie;
+	int handler_id;
+
+	libbpf_prog_setup_fn_t prog_setup_fn;
+	libbpf_prog_prepare_load_fn_t prog_prepare_load_fn;
+	libbpf_prog_attach_fn_t prog_attach_fn;
+};
+
+/*
+ * bpf_prog should be a better name but it has been used in
+ * linux/filter.h.
+ */
+struct bpf_program {
+	char *name;
+	char *sec_name;
+	size_t sec_idx;
+	const struct bpf_sec_def *sec_def;
+	/* this program's instruction offset (in number of instructions)
+	 * within its containing ELF section
+	 */
+	size_t sec_insn_off;
+	/* number of original instructions in ELF section belonging to this
+	 * program, not taking into account subprogram instructions possible
+	 * appended later during relocation
+	 */
+	size_t sec_insn_cnt;
+	/* Offset (in number of instructions) of the start of instruction
+	 * belonging to this BPF program  within its containing main BPF
+	 * program. For the entry-point (main) BPF program, this is always
+	 * zero. For a sub-program, this gets reset before each of main BPF
+	 * programs are processed and relocated and is used to determined
+	 * whether sub-program was already appended to the main program, and
+	 * if yes, at which instruction offset.
+	 */
+	size_t sub_insn_off;
+
+	/* instructions that belong to BPF program; insns[0] is located at
+	 * sec_insn_off instruction within its ELF section in ELF file, so
+	 * when mapping ELF file instruction index to the local instruction,
+	 * one needs to subtract sec_insn_off; and vice versa.
+	 */
+	struct bpf_insn *insns;
+	/* actual number of instruction in this BPF program's image; for
+	 * entry-point BPF programs this includes the size of main program
+	 * itself plus all the used sub-programs, appended at the end
+	 */
+	size_t insns_cnt;
+
+	struct reloc_desc *reloc_desc;
+	int nr_reloc;
+
+	/* BPF verifier log settings */
+	char *log_buf;
+	size_t log_size;
+	__u32 log_level;
+
+	struct bpf_object *obj;
+
+	int fd;
+	bool autoload;
+	bool autoattach;
+	bool mark_btf_static;
+	enum bpf_prog_type type;
+	enum bpf_attach_type expected_attach_type;
+
+	int prog_ifindex;
+	__u32 attach_btf_obj_fd;
+	__u32 attach_btf_id;
+	__u32 attach_prog_fd;
+
+	void *func_info;
+	__u32 func_info_rec_size;
+	__u32 func_info_cnt;
+
+	void *line_info;
+	__u32 line_info_rec_size;
+	__u32 line_info_cnt;
+	__u32 prog_flags;
+};
+
+struct bpf_struct_ops {
+	const char *tname;
+	const struct btf_type *type;
+	struct bpf_program **progs;
+	__u32 *kern_func_off;
+	/* e.g. struct tcp_congestion_ops in bpf_prog's btf format */
+	void *data;
+	/* e.g. struct bpf_struct_ops_tcp_congestion_ops in
+	 *      btf_vmlinux's format.
+	 * struct bpf_struct_ops_tcp_congestion_ops {
+	 *	[... some other kernel fields ...]
+	 *	struct tcp_congestion_ops data;
+	 * }
+	 * kern_vdata-size == sizeof(struct bpf_struct_ops_tcp_congestion_ops)
+	 * bpf_map__init_kern_struct_ops() will populate the "kern_vdata"
+	 * from "data".
+	 */
+	void *kern_vdata;
+	__u32 type_id;
+};
+
+#define DATA_SEC ".data"
+#define BSS_SEC ".bss"
+#define RODATA_SEC ".rodata"
+#define KCONFIG_SEC ".kconfig"
+#define KSYMS_SEC ".ksyms"
+#define STRUCT_OPS_SEC ".struct_ops"
+
+enum libbpf_map_type {
+	LIBBPF_MAP_UNSPEC,
+	LIBBPF_MAP_DATA,
+	LIBBPF_MAP_BSS,
+	LIBBPF_MAP_RODATA,
+	LIBBPF_MAP_KCONFIG,
+};
+
+struct bpf_map_def {
+	unsigned int type;
+	unsigned int key_size;
+	unsigned int value_size;
+	unsigned int max_entries;
+	unsigned int map_flags;
+};
+
+struct bpf_map {
+	struct bpf_object *obj;
+	char *name;
+	/* real_name is defined for special internal maps (.rodata*,
+	 * .data*, .bss, .kconfig) and preserves their original ELF section
+	 * name. This is important to be able to find corresponding BTF
+	 * DATASEC information.
+	 */
+	char *real_name;
+	int fd;
+	int sec_idx;
+	size_t sec_offset;
+	int map_ifindex;
+	int inner_map_fd;
+	struct bpf_map_def def;
+	__u32 numa_node;
+	__u32 btf_var_idx;
+	__u32 btf_key_type_id;
+	__u32 btf_value_type_id;
+	__u32 btf_vmlinux_value_type_id;
+	enum libbpf_map_type libbpf_type;
+	void *mmaped;
+	struct bpf_struct_ops *st_ops;
+	struct bpf_map *inner_map;
+	void **init_slots;
+	int init_slots_sz;
+	char *pin_path;
+	bool pinned;
+	bool reused;
+	bool autocreate;
+	__u64 map_extra;
+};
+
+enum extern_type {
+	EXT_UNKNOWN,
+	EXT_KCFG,
+	EXT_KSYM,
+};
+
+enum kcfg_type {
+	KCFG_UNKNOWN,
+	KCFG_CHAR,
+	KCFG_BOOL,
+	KCFG_INT,
+	KCFG_TRISTATE,
+	KCFG_CHAR_ARR,
+};
+
+struct extern_desc {
+	enum extern_type type;
+	int sym_idx;
+	int btf_id;
+	int sec_btf_id;
+	const char *name;
+	bool is_set;
+	bool is_weak;
+	union {
+		struct {
+			enum kcfg_type type;
+			int sz;
+			int align;
+			int data_off;
+			bool is_signed;
+		} kcfg;
+		struct {
+			unsigned long long addr;
+
+			/* target btf_id of the corresponding kernel var. */
+			int kernel_btf_obj_fd;
+			int kernel_btf_id;
+
+			/* local btf_id of the ksym extern's type. */
+			__u32 type_id;
+			/* BTF fd index to be patched in for insn->off, this is
+			 * 0 for vmlinux BTF, index in obj->fd_array for module
+			 * BTF
+			 */
+			__s16 btf_fd_idx;
+		} ksym;
+	};
+};
+
+struct module_btf {
+	struct btf *btf;
+	char *name;
+	__u32 id;
+	int fd;
+	int fd_array_idx;
+};
+
+enum sec_type {
+	SEC_UNUSED = 0,
+	SEC_RELO,
+	SEC_BSS,
+	SEC_DATA,
+	SEC_RODATA,
+};
+
+struct elf_sec_desc {
+	enum sec_type sec_type;
+	Elf64_Shdr *shdr;
+	Elf_Data *data;
+};
+
+struct elf_state {
+	int fd;
+	const void *obj_buf;
+	size_t obj_buf_sz;
+	Elf *elf;
+	Elf64_Ehdr *ehdr;
+	Elf_Data *symbols;
+	Elf_Data *st_ops_data;
+	size_t shstrndx; /* section index for section name strings */
+	size_t strtabidx;
+	struct elf_sec_desc *secs;
+	size_t sec_cnt;
+	int btf_maps_shndx;
+	__u32 btf_maps_sec_btf_id;
+	int text_shndx;
+	int symbols_shndx;
+	int st_ops_shndx;
+};
+
+struct usdt_manager;
+
+struct bpf_object {
+	char name[BPF_OBJ_NAME_LEN];
+	char license[64];
+	__u32 kern_version;
+
+	struct bpf_program *programs;
+	size_t nr_programs;
+	struct bpf_map *maps;
+	size_t nr_maps;
+	size_t maps_cap;
+
+	char *kconfig;
+	struct extern_desc *externs;
+	int nr_extern;
+	int kconfig_map_idx;
+
+	bool loaded;
+	bool has_subcalls;
+	bool has_rodata;
+
+	struct bpf_gen *gen_loader;
+
+	/* Information when doing ELF related work. Only valid if efile.elf is not NULL */
+	struct elf_state efile;
+
+	struct btf *btf;
+	struct btf_ext *btf_ext;
+
+	/* Parse and load BTF vmlinux if any of the programs in the object need
+	 * it at load time.
+	 */
+	struct btf *btf_vmlinux;
+	/* Path to the custom BTF to be used for BPF CO-RE relocations as an
+	 * override for vmlinux BTF.
+	 */
+	char *btf_custom_path;
+	/* vmlinux BTF override for CO-RE relocations */
+	struct btf *btf_vmlinux_override;
+	/* Lazily initialized kernel module BTFs */
+	struct module_btf *btf_modules;
+	bool btf_modules_loaded;
+	size_t btf_module_cnt;
+	size_t btf_module_cap;
+
+	/* optional log settings passed to BPF_BTF_LOAD and BPF_PROG_LOAD commands */
+	char *log_buf;
+	size_t log_size;
+	__u32 log_level;
+
+	int *fd_array;
+	size_t fd_array_cap;
+	size_t fd_array_cnt;
+
+	struct usdt_manager *usdt_man;
+
+	char path[];
+};
+
+static const char *elf_sym_str(const struct bpf_object *obj, size_t off);
+static const char *elf_sec_str(const struct bpf_object *obj, size_t off);
+static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx);
+static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name);
+static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn);
+static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn);
+static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn);
+static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx);
+static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx);
+
+void bpf_program__unload(struct bpf_program *prog)
+{
+	if (!prog)
+		return;
+
+	zclose(prog->fd);
+
+	zfree(&prog->func_info);
+	zfree(&prog->line_info);
+}
+
+static void bpf_program__exit(struct bpf_program *prog)
+{
+	if (!prog)
+		return;
+
+	bpf_program__unload(prog);
+	zfree(&prog->name);
+	zfree(&prog->sec_name);
+	zfree(&prog->insns);
+	zfree(&prog->reloc_desc);
+
+	prog->nr_reloc = 0;
+	prog->insns_cnt = 0;
+	prog->sec_idx = -1;
+}
+
+static bool insn_is_subprog_call(const struct bpf_insn *insn)
+{
+	return BPF_CLASS(insn->code) == BPF_JMP &&
+	       BPF_OP(insn->code) == BPF_CALL &&
+	       BPF_SRC(insn->code) == BPF_K &&
+	       insn->src_reg == BPF_PSEUDO_CALL &&
+	       insn->dst_reg == 0 &&
+	       insn->off == 0;
+}
+
+static bool is_call_insn(const struct bpf_insn *insn)
+{
+	return insn->code == (BPF_JMP | BPF_CALL);
+}
+
+static bool insn_is_pseudo_func(struct bpf_insn *insn)
+{
+	return is_ldimm64_insn(insn) && insn->src_reg == BPF_PSEUDO_FUNC;
+}
+
+static int
+bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog,
+		      const char *name, size_t sec_idx, const char *sec_name,
+		      size_t sec_off, void *insn_data, size_t insn_data_sz)
+{
+	if (insn_data_sz == 0 || insn_data_sz % BPF_INSN_SZ || sec_off % BPF_INSN_SZ) {
+		pr_warn("sec '%s': corrupted program '%s', offset %zu, size %zu\n",
+			sec_name, name, sec_off, insn_data_sz);
+		return -EINVAL;
+	}
+
+	memset(prog, 0, sizeof(*prog));
+	prog->obj = obj;
+
+	prog->sec_idx = sec_idx;
+	prog->sec_insn_off = sec_off / BPF_INSN_SZ;
+	prog->sec_insn_cnt = insn_data_sz / BPF_INSN_SZ;
+	/* insns_cnt can later be increased by appending used subprograms */
+	prog->insns_cnt = prog->sec_insn_cnt;
+
+	prog->type = BPF_PROG_TYPE_UNSPEC;
+	prog->fd = -1;
+
+	/* libbpf's convention for SEC("?abc...") is that it's just like
+	 * SEC("abc...") but the corresponding bpf_program starts out with
+	 * autoload set to false.
+	 */
+	if (sec_name[0] == '?') {
+		prog->autoload = false;
+		/* from now on forget there was ? in section name */
+		sec_name++;
+	} else {
+		prog->autoload = true;
+	}
+
+	prog->autoattach = true;
+
+	/* inherit object's log_level */
+	prog->log_level = obj->log_level;
+
+	prog->sec_name = strdup(sec_name);
+	if (!prog->sec_name)
+		goto errout;
+
+	prog->name = strdup(name);
+	if (!prog->name)
+		goto errout;
+
+	prog->insns = malloc(insn_data_sz);
+	if (!prog->insns)
+		goto errout;
+	memcpy(prog->insns, insn_data, insn_data_sz);
+
+	return 0;
+errout:
+	pr_warn("sec '%s': failed to allocate memory for prog '%s'\n", sec_name, name);
+	bpf_program__exit(prog);
+	return -ENOMEM;
+}
+
+static int
+bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
+			 const char *sec_name, int sec_idx)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	struct bpf_program *prog, *progs;
+	void *data = sec_data->d_buf;
+	size_t sec_sz = sec_data->d_size, sec_off, prog_sz, nr_syms;
+	int nr_progs, err, i;
+	const char *name;
+	Elf64_Sym *sym;
+
+	progs = obj->programs;
+	nr_progs = obj->nr_programs;
+	nr_syms = symbols->d_size / sizeof(Elf64_Sym);
+	sec_off = 0;
+
+	for (i = 0; i < nr_syms; i++) {
+		sym = elf_sym_by_idx(obj, i);
+
+		if (sym->st_shndx != sec_idx)
+			continue;
+		if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
+			continue;
+
+		prog_sz = sym->st_size;
+		sec_off = sym->st_value;
+
+		name = elf_sym_str(obj, sym->st_name);
+		if (!name) {
+			pr_warn("sec '%s': failed to get symbol name for offset %zu\n",
+				sec_name, sec_off);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		if (sec_off + prog_sz > sec_sz) {
+			pr_warn("sec '%s': program at offset %zu crosses section boundary\n",
+				sec_name, sec_off);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		if (sec_idx != obj->efile.text_shndx && ELF64_ST_BIND(sym->st_info) == STB_LOCAL) {
+			pr_warn("sec '%s': program '%s' is static and not supported\n", sec_name, name);
+			return -ENOTSUP;
+		}
+
+		pr_debug("sec '%s': found program '%s' at insn offset %zu (%zu bytes), code size %zu insns (%zu bytes)\n",
+			 sec_name, name, sec_off / BPF_INSN_SZ, sec_off, prog_sz / BPF_INSN_SZ, prog_sz);
+
+		progs = libbpf_reallocarray(progs, nr_progs + 1, sizeof(*progs));
+		if (!progs) {
+			/*
+			 * In this case the original obj->programs
+			 * is still valid, so don't need special treat for
+			 * bpf_close_object().
+			 */
+			pr_warn("sec '%s': failed to alloc memory for new program '%s'\n",
+				sec_name, name);
+			return -ENOMEM;
+		}
+		obj->programs = progs;
+
+		prog = &progs[nr_progs];
+
+		err = bpf_object__init_prog(obj, prog, name, sec_idx, sec_name,
+					    sec_off, data + sec_off, prog_sz);
+		if (err)
+			return err;
+
+		/* if function is a global/weak symbol, but has restricted
+		 * (STV_HIDDEN or STV_INTERNAL) visibility, mark its BTF FUNC
+		 * as static to enable more permissive BPF verification mode
+		 * with more outside context available to BPF verifier
+		 */
+		if (ELF64_ST_BIND(sym->st_info) != STB_LOCAL
+		    && (ELF64_ST_VISIBILITY(sym->st_other) == STV_HIDDEN
+			|| ELF64_ST_VISIBILITY(sym->st_other) == STV_INTERNAL))
+			prog->mark_btf_static = true;
+
+		nr_progs++;
+		obj->nr_programs = nr_progs;
+	}
+
+	return 0;
+}
+
+__u32 get_kernel_version(void)
+{
+	/* On Ubuntu LINUX_VERSION_CODE doesn't correspond to info.release,
+	 * but Ubuntu provides /proc/version_signature file, as described at
+	 * https://ubuntu.com/kernel, with an example contents below, which we
+	 * can use to get a proper LINUX_VERSION_CODE.
+	 *
+	 *   Ubuntu 5.4.0-12.15-generic 5.4.8
+	 *
+	 * In the above, 5.4.8 is what kernel is actually expecting, while
+	 * uname() call will return 5.4.0 in info.release.
+	 */
+	const char *ubuntu_kver_file = "/proc/version_signature";
+	__u32 major, minor, patch;
+	struct utsname info;
+
+	if (faccessat(AT_FDCWD, ubuntu_kver_file, R_OK, AT_EACCESS) == 0) {
+		FILE *f;
+
+		f = fopen(ubuntu_kver_file, "r");
+		if (f) {
+			if (fscanf(f, "%*s %*s %d.%d.%d\n", &major, &minor, &patch) == 3) {
+				fclose(f);
+				return KERNEL_VERSION(major, minor, patch);
+			}
+			fclose(f);
+		}
+		/* something went wrong, fall back to uname() approach */
+	}
+
+	uname(&info);
+	if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3)
+		return 0;
+	return KERNEL_VERSION(major, minor, patch);
+}
+
+static const struct btf_member *
+find_member_by_offset(const struct btf_type *t, __u32 bit_offset)
+{
+	struct btf_member *m;
+	int i;
+
+	for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
+		if (btf_member_bit_offset(t, i) == bit_offset)
+			return m;
+	}
+
+	return NULL;
+}
+
+static const struct btf_member *
+find_member_by_name(const struct btf *btf, const struct btf_type *t,
+		    const char *name)
+{
+	struct btf_member *m;
+	int i;
+
+	for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
+		if (!strcmp(btf__name_by_offset(btf, m->name_off), name))
+			return m;
+	}
+
+	return NULL;
+}
+
+#define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_"
+static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
+				   const char *name, __u32 kind);
+
+static int
+find_struct_ops_kern_types(const struct btf *btf, const char *tname,
+			   const struct btf_type **type, __u32 *type_id,
+			   const struct btf_type **vtype, __u32 *vtype_id,
+			   const struct btf_member **data_member)
+{
+	const struct btf_type *kern_type, *kern_vtype;
+	const struct btf_member *kern_data_member;
+	__s32 kern_vtype_id, kern_type_id;
+	__u32 i;
+
+	kern_type_id = btf__find_by_name_kind(btf, tname, BTF_KIND_STRUCT);
+	if (kern_type_id < 0) {
+		pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n",
+			tname);
+		return kern_type_id;
+	}
+	kern_type = btf__type_by_id(btf, kern_type_id);
+
+	/* Find the corresponding "map_value" type that will be used
+	 * in map_update(BPF_MAP_TYPE_STRUCT_OPS).  For example,
+	 * find "struct bpf_struct_ops_tcp_congestion_ops" from the
+	 * btf_vmlinux.
+	 */
+	kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX,
+						tname, BTF_KIND_STRUCT);
+	if (kern_vtype_id < 0) {
+		pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n",
+			STRUCT_OPS_VALUE_PREFIX, tname);
+		return kern_vtype_id;
+	}
+	kern_vtype = btf__type_by_id(btf, kern_vtype_id);
+
+	/* Find "struct tcp_congestion_ops" from
+	 * struct bpf_struct_ops_tcp_congestion_ops {
+	 *	[ ... ]
+	 *	struct tcp_congestion_ops data;
+	 * }
+	 */
+	kern_data_member = btf_members(kern_vtype);
+	for (i = 0; i < btf_vlen(kern_vtype); i++, kern_data_member++) {
+		if (kern_data_member->type == kern_type_id)
+			break;
+	}
+	if (i == btf_vlen(kern_vtype)) {
+		pr_warn("struct_ops init_kern: struct %s data is not found in struct %s%s\n",
+			tname, STRUCT_OPS_VALUE_PREFIX, tname);
+		return -EINVAL;
+	}
+
+	*type = kern_type;
+	*type_id = kern_type_id;
+	*vtype = kern_vtype;
+	*vtype_id = kern_vtype_id;
+	*data_member = kern_data_member;
+
+	return 0;
+}
+
+static bool bpf_map__is_struct_ops(const struct bpf_map *map)
+{
+	return map->def.type == BPF_MAP_TYPE_STRUCT_OPS;
+}
+
+/* Init the map's fields that depend on kern_btf */
+static int bpf_map__init_kern_struct_ops(struct bpf_map *map,
+					 const struct btf *btf,
+					 const struct btf *kern_btf)
+{
+	const struct btf_member *member, *kern_member, *kern_data_member;
+	const struct btf_type *type, *kern_type, *kern_vtype;
+	__u32 i, kern_type_id, kern_vtype_id, kern_data_off;
+	struct bpf_struct_ops *st_ops;
+	void *data, *kern_data;
+	const char *tname;
+	int err;
+
+	st_ops = map->st_ops;
+	type = st_ops->type;
+	tname = st_ops->tname;
+	err = find_struct_ops_kern_types(kern_btf, tname,
+					 &kern_type, &kern_type_id,
+					 &kern_vtype, &kern_vtype_id,
+					 &kern_data_member);
+	if (err)
+		return err;
+
+	pr_debug("struct_ops init_kern %s: type_id:%u kern_type_id:%u kern_vtype_id:%u\n",
+		 map->name, st_ops->type_id, kern_type_id, kern_vtype_id);
+
+	map->def.value_size = kern_vtype->size;
+	map->btf_vmlinux_value_type_id = kern_vtype_id;
+
+	st_ops->kern_vdata = calloc(1, kern_vtype->size);
+	if (!st_ops->kern_vdata)
+		return -ENOMEM;
+
+	data = st_ops->data;
+	kern_data_off = kern_data_member->offset / 8;
+	kern_data = st_ops->kern_vdata + kern_data_off;
+
+	member = btf_members(type);
+	for (i = 0; i < btf_vlen(type); i++, member++) {
+		const struct btf_type *mtype, *kern_mtype;
+		__u32 mtype_id, kern_mtype_id;
+		void *mdata, *kern_mdata;
+		__s64 msize, kern_msize;
+		__u32 moff, kern_moff;
+		__u32 kern_member_idx;
+		const char *mname;
+
+		mname = btf__name_by_offset(btf, member->name_off);
+		kern_member = find_member_by_name(kern_btf, kern_type, mname);
+		if (!kern_member) {
+			pr_warn("struct_ops init_kern %s: Cannot find member %s in kernel BTF\n",
+				map->name, mname);
+			return -ENOTSUP;
+		}
+
+		kern_member_idx = kern_member - btf_members(kern_type);
+		if (btf_member_bitfield_size(type, i) ||
+		    btf_member_bitfield_size(kern_type, kern_member_idx)) {
+			pr_warn("struct_ops init_kern %s: bitfield %s is not supported\n",
+				map->name, mname);
+			return -ENOTSUP;
+		}
+
+		moff = member->offset / 8;
+		kern_moff = kern_member->offset / 8;
+
+		mdata = data + moff;
+		kern_mdata = kern_data + kern_moff;
+
+		mtype = skip_mods_and_typedefs(btf, member->type, &mtype_id);
+		kern_mtype = skip_mods_and_typedefs(kern_btf, kern_member->type,
+						    &kern_mtype_id);
+		if (BTF_INFO_KIND(mtype->info) !=
+		    BTF_INFO_KIND(kern_mtype->info)) {
+			pr_warn("struct_ops init_kern %s: Unmatched member type %s %u != %u(kernel)\n",
+				map->name, mname, BTF_INFO_KIND(mtype->info),
+				BTF_INFO_KIND(kern_mtype->info));
+			return -ENOTSUP;
+		}
+
+		if (btf_is_ptr(mtype)) {
+			struct bpf_program *prog;
+
+			prog = st_ops->progs[i];
+			if (!prog)
+				continue;
+
+			kern_mtype = skip_mods_and_typedefs(kern_btf,
+							    kern_mtype->type,
+							    &kern_mtype_id);
+
+			/* mtype->type must be a func_proto which was
+			 * guaranteed in bpf_object__collect_st_ops_relos(),
+			 * so only check kern_mtype for func_proto here.
+			 */
+			if (!btf_is_func_proto(kern_mtype)) {
+				pr_warn("struct_ops init_kern %s: kernel member %s is not a func ptr\n",
+					map->name, mname);
+				return -ENOTSUP;
+			}
+
+			prog->attach_btf_id = kern_type_id;
+			prog->expected_attach_type = kern_member_idx;
+
+			st_ops->kern_func_off[i] = kern_data_off + kern_moff;
+
+			pr_debug("struct_ops init_kern %s: func ptr %s is set to prog %s from data(+%u) to kern_data(+%u)\n",
+				 map->name, mname, prog->name, moff,
+				 kern_moff);
+
+			continue;
+		}
+
+		msize = btf__resolve_size(btf, mtype_id);
+		kern_msize = btf__resolve_size(kern_btf, kern_mtype_id);
+		if (msize < 0 || kern_msize < 0 || msize != kern_msize) {
+			pr_warn("struct_ops init_kern %s: Error in size of member %s: %zd != %zd(kernel)\n",
+				map->name, mname, (ssize_t)msize,
+				(ssize_t)kern_msize);
+			return -ENOTSUP;
+		}
+
+		pr_debug("struct_ops init_kern %s: copy %s %u bytes from data(+%u) to kern_data(+%u)\n",
+			 map->name, mname, (unsigned int)msize,
+			 moff, kern_moff);
+		memcpy(kern_mdata, mdata, msize);
+	}
+
+	return 0;
+}
+
+static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
+{
+	struct bpf_map *map;
+	size_t i;
+	int err;
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		map = &obj->maps[i];
+
+		if (!bpf_map__is_struct_ops(map))
+			continue;
+
+		err = bpf_map__init_kern_struct_ops(map, obj->btf,
+						    obj->btf_vmlinux);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int bpf_object__init_struct_ops_maps(struct bpf_object *obj)
+{
+	const struct btf_type *type, *datasec;
+	const struct btf_var_secinfo *vsi;
+	struct bpf_struct_ops *st_ops;
+	const char *tname, *var_name;
+	__s32 type_id, datasec_id;
+	const struct btf *btf;
+	struct bpf_map *map;
+	__u32 i;
+
+	if (obj->efile.st_ops_shndx == -1)
+		return 0;
+
+	btf = obj->btf;
+	datasec_id = btf__find_by_name_kind(btf, STRUCT_OPS_SEC,
+					    BTF_KIND_DATASEC);
+	if (datasec_id < 0) {
+		pr_warn("struct_ops init: DATASEC %s not found\n",
+			STRUCT_OPS_SEC);
+		return -EINVAL;
+	}
+
+	datasec = btf__type_by_id(btf, datasec_id);
+	vsi = btf_var_secinfos(datasec);
+	for (i = 0; i < btf_vlen(datasec); i++, vsi++) {
+		type = btf__type_by_id(obj->btf, vsi->type);
+		var_name = btf__name_by_offset(obj->btf, type->name_off);
+
+		type_id = btf__resolve_type(obj->btf, vsi->type);
+		if (type_id < 0) {
+			pr_warn("struct_ops init: Cannot resolve var type_id %u in DATASEC %s\n",
+				vsi->type, STRUCT_OPS_SEC);
+			return -EINVAL;
+		}
+
+		type = btf__type_by_id(obj->btf, type_id);
+		tname = btf__name_by_offset(obj->btf, type->name_off);
+		if (!tname[0]) {
+			pr_warn("struct_ops init: anonymous type is not supported\n");
+			return -ENOTSUP;
+		}
+		if (!btf_is_struct(type)) {
+			pr_warn("struct_ops init: %s is not a struct\n", tname);
+			return -EINVAL;
+		}
+
+		map = bpf_object__add_map(obj);
+		if (IS_ERR(map))
+			return PTR_ERR(map);
+
+		map->sec_idx = obj->efile.st_ops_shndx;
+		map->sec_offset = vsi->offset;
+		map->name = strdup(var_name);
+		if (!map->name)
+			return -ENOMEM;
+
+		map->def.type = BPF_MAP_TYPE_STRUCT_OPS;
+		map->def.key_size = sizeof(int);
+		map->def.value_size = type->size;
+		map->def.max_entries = 1;
+
+		map->st_ops = calloc(1, sizeof(*map->st_ops));
+		if (!map->st_ops)
+			return -ENOMEM;
+		st_ops = map->st_ops;
+		st_ops->data = malloc(type->size);
+		st_ops->progs = calloc(btf_vlen(type), sizeof(*st_ops->progs));
+		st_ops->kern_func_off = malloc(btf_vlen(type) *
+					       sizeof(*st_ops->kern_func_off));
+		if (!st_ops->data || !st_ops->progs || !st_ops->kern_func_off)
+			return -ENOMEM;
+
+		if (vsi->offset + type->size > obj->efile.st_ops_data->d_size) {
+			pr_warn("struct_ops init: var %s is beyond the end of DATASEC %s\n",
+				var_name, STRUCT_OPS_SEC);
+			return -EINVAL;
+		}
+
+		memcpy(st_ops->data,
+		       obj->efile.st_ops_data->d_buf + vsi->offset,
+		       type->size);
+		st_ops->tname = tname;
+		st_ops->type = type;
+		st_ops->type_id = type_id;
+
+		pr_debug("struct_ops init: struct %s(type_id=%u) %s found at offset %u\n",
+			 tname, type_id, var_name, vsi->offset);
+	}
+
+	return 0;
+}
+
+static struct bpf_object *bpf_object__new(const char *path,
+					  const void *obj_buf,
+					  size_t obj_buf_sz,
+					  const char *obj_name)
+{
+	struct bpf_object *obj;
+	char *end;
+
+	obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
+	if (!obj) {
+		pr_warn("alloc memory failed for %s\n", path);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	strcpy(obj->path, path);
+	if (obj_name) {
+		libbpf_strlcpy(obj->name, obj_name, sizeof(obj->name));
+	} else {
+		/* Using basename() GNU version which doesn't modify arg. */
+		libbpf_strlcpy(obj->name, basename((void *)path), sizeof(obj->name));
+		end = strchr(obj->name, '.');
+		if (end)
+			*end = 0;
+	}
+
+	obj->efile.fd = -1;
+	/*
+	 * Caller of this function should also call
+	 * bpf_object__elf_finish() after data collection to return
+	 * obj_buf to user. If not, we should duplicate the buffer to
+	 * avoid user freeing them before elf finish.
+	 */
+	obj->efile.obj_buf = obj_buf;
+	obj->efile.obj_buf_sz = obj_buf_sz;
+	obj->efile.btf_maps_shndx = -1;
+	obj->efile.st_ops_shndx = -1;
+	obj->kconfig_map_idx = -1;
+
+	obj->kern_version = get_kernel_version();
+	obj->loaded = false;
+
+	return obj;
+}
+
+static void bpf_object__elf_finish(struct bpf_object *obj)
+{
+	if (!obj->efile.elf)
+		return;
+
+	elf_end(obj->efile.elf);
+	obj->efile.elf = NULL;
+	obj->efile.symbols = NULL;
+	obj->efile.st_ops_data = NULL;
+
+	zfree(&obj->efile.secs);
+	obj->efile.sec_cnt = 0;
+	zclose(obj->efile.fd);
+	obj->efile.obj_buf = NULL;
+	obj->efile.obj_buf_sz = 0;
+}
+
+static int bpf_object__elf_init(struct bpf_object *obj)
+{
+	Elf64_Ehdr *ehdr;
+	int err = 0;
+	Elf *elf;
+
+	if (obj->efile.elf) {
+		pr_warn("elf: init internal error\n");
+		return -LIBBPF_ERRNO__LIBELF;
+	}
+
+	if (obj->efile.obj_buf_sz > 0) {
+		/* obj_buf should have been validated by bpf_object__open_mem(). */
+		elf = elf_memory((char *)obj->efile.obj_buf, obj->efile.obj_buf_sz);
+	} else {
+		obj->efile.fd = open(obj->path, O_RDONLY | O_CLOEXEC);
+		if (obj->efile.fd < 0) {
+			char errmsg[STRERR_BUFSIZE], *cp;
+
+			err = -errno;
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+			pr_warn("elf: failed to open %s: %s\n", obj->path, cp);
+			return err;
+		}
+
+		elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL);
+	}
+
+	if (!elf) {
+		pr_warn("elf: failed to open %s as ELF file: %s\n", obj->path, elf_errmsg(-1));
+		err = -LIBBPF_ERRNO__LIBELF;
+		goto errout;
+	}
+
+	obj->efile.elf = elf;
+
+	if (elf_kind(elf) != ELF_K_ELF) {
+		err = -LIBBPF_ERRNO__FORMAT;
+		pr_warn("elf: '%s' is not a proper ELF object\n", obj->path);
+		goto errout;
+	}
+
+	if (gelf_getclass(elf) != ELFCLASS64) {
+		err = -LIBBPF_ERRNO__FORMAT;
+		pr_warn("elf: '%s' is not a 64-bit ELF object\n", obj->path);
+		goto errout;
+	}
+
+	obj->efile.ehdr = ehdr = elf64_getehdr(elf);
+	if (!obj->efile.ehdr) {
+		pr_warn("elf: failed to get ELF header from %s: %s\n", obj->path, elf_errmsg(-1));
+		err = -LIBBPF_ERRNO__FORMAT;
+		goto errout;
+	}
+
+	if (elf_getshdrstrndx(elf, &obj->efile.shstrndx)) {
+		pr_warn("elf: failed to get section names section index for %s: %s\n",
+			obj->path, elf_errmsg(-1));
+		err = -LIBBPF_ERRNO__FORMAT;
+		goto errout;
+	}
+
+	/* Elf is corrupted/truncated, avoid calling elf_strptr. */
+	if (!elf_rawdata(elf_getscn(elf, obj->efile.shstrndx), NULL)) {
+		pr_warn("elf: failed to get section names strings from %s: %s\n",
+			obj->path, elf_errmsg(-1));
+		err = -LIBBPF_ERRNO__FORMAT;
+		goto errout;
+	}
+
+	/* Old LLVM set e_machine to EM_NONE */
+	if (ehdr->e_type != ET_REL || (ehdr->e_machine && ehdr->e_machine != EM_BPF)) {
+		pr_warn("elf: %s is not a valid eBPF object file\n", obj->path);
+		err = -LIBBPF_ERRNO__FORMAT;
+		goto errout;
+	}
+
+	return 0;
+errout:
+	bpf_object__elf_finish(obj);
+	return err;
+}
+
+static int bpf_object__check_endianness(struct bpf_object *obj)
+{
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
+		return 0;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+	if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
+		return 0;
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+	pr_warn("elf: endianness mismatch in %s.\n", obj->path);
+	return -LIBBPF_ERRNO__ENDIAN;
+}
+
+static int
+bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
+{
+	if (!data) {
+		pr_warn("invalid license section in %s\n", obj->path);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	/* libbpf_strlcpy() only copies first N - 1 bytes, so size + 1 won't
+	 * go over allowed ELF data section buffer
+	 */
+	libbpf_strlcpy(obj->license, data, min(size + 1, sizeof(obj->license)));
+	pr_debug("license of %s is %s\n", obj->path, obj->license);
+	return 0;
+}
+
+static int
+bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size)
+{
+	__u32 kver;
+
+	if (!data || size != sizeof(kver)) {
+		pr_warn("invalid kver section in %s\n", obj->path);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	memcpy(&kver, data, sizeof(kver));
+	obj->kern_version = kver;
+	pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version);
+	return 0;
+}
+
+static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)
+{
+	if (type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
+	    type == BPF_MAP_TYPE_HASH_OF_MAPS)
+		return true;
+	return false;
+}
+
+static int find_elf_sec_sz(const struct bpf_object *obj, const char *name, __u32 *size)
+{
+	Elf_Data *data;
+	Elf_Scn *scn;
+
+	if (!name)
+		return -EINVAL;
+
+	scn = elf_sec_by_name(obj, name);
+	data = elf_sec_data(obj, scn);
+	if (data) {
+		*size = data->d_size;
+		return 0; /* found it */
+	}
+
+	return -ENOENT;
+}
+
+static Elf64_Sym *find_elf_var_sym(const struct bpf_object *obj, const char *name)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	const char *sname;
+	size_t si;
+
+	for (si = 0; si < symbols->d_size / sizeof(Elf64_Sym); si++) {
+		Elf64_Sym *sym = elf_sym_by_idx(obj, si);
+
+		if (ELF64_ST_TYPE(sym->st_info) != STT_OBJECT)
+			continue;
+
+		if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL &&
+		    ELF64_ST_BIND(sym->st_info) != STB_WEAK)
+			continue;
+
+		sname = elf_sym_str(obj, sym->st_name);
+		if (!sname) {
+			pr_warn("failed to get sym name string for var %s\n", name);
+			return ERR_PTR(-EIO);
+		}
+		if (strcmp(name, sname) == 0)
+			return sym;
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+
+static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
+{
+	struct bpf_map *map;
+	int err;
+
+	err = libbpf_ensure_mem((void **)&obj->maps, &obj->maps_cap,
+				sizeof(*obj->maps), obj->nr_maps + 1);
+	if (err)
+		return ERR_PTR(err);
+
+	map = &obj->maps[obj->nr_maps++];
+	map->obj = obj;
+	map->fd = -1;
+	map->inner_map_fd = -1;
+	map->autocreate = true;
+
+	return map;
+}
+
+static size_t bpf_map_mmap_sz(const struct bpf_map *map)
+{
+	long page_sz = sysconf(_SC_PAGE_SIZE);
+	size_t map_sz;
+
+	map_sz = (size_t)roundup(map->def.value_size, 8) * map->def.max_entries;
+	map_sz = roundup(map_sz, page_sz);
+	return map_sz;
+}
+
+static char *internal_map_name(struct bpf_object *obj, const char *real_name)
+{
+	char map_name[BPF_OBJ_NAME_LEN], *p;
+	int pfx_len, sfx_len = max((size_t)7, strlen(real_name));
+
+	/* This is one of the more confusing parts of libbpf for various
+	 * reasons, some of which are historical. The original idea for naming
+	 * internal names was to include as much of BPF object name prefix as
+	 * possible, so that it can be distinguished from similar internal
+	 * maps of a different BPF object.
+	 * As an example, let's say we have bpf_object named 'my_object_name'
+	 * and internal map corresponding to '.rodata' ELF section. The final
+	 * map name advertised to user and to the kernel will be
+	 * 'my_objec.rodata', taking first 8 characters of object name and
+	 * entire 7 characters of '.rodata'.
+	 * Somewhat confusingly, if internal map ELF section name is shorter
+	 * than 7 characters, e.g., '.bss', we still reserve 7 characters
+	 * for the suffix, even though we only have 4 actual characters, and
+	 * resulting map will be called 'my_objec.bss', not even using all 15
+	 * characters allowed by the kernel. Oh well, at least the truncated
+	 * object name is somewhat consistent in this case. But if the map
+	 * name is '.kconfig', we'll still have entirety of '.kconfig' added
+	 * (8 chars) and thus will be left with only first 7 characters of the
+	 * object name ('my_obje'). Happy guessing, user, that the final map
+	 * name will be "my_obje.kconfig".
+	 * Now, with libbpf starting to support arbitrarily named .rodata.*
+	 * and .data.* data sections, it's possible that ELF section name is
+	 * longer than allowed 15 chars, so we now need to be careful to take
+	 * only up to 15 first characters of ELF name, taking no BPF object
+	 * name characters at all. So '.rodata.abracadabra' will result in
+	 * '.rodata.abracad' kernel and user-visible name.
+	 * We need to keep this convoluted logic intact for .data, .bss and
+	 * .rodata maps, but for new custom .data.custom and .rodata.custom
+	 * maps we use their ELF names as is, not prepending bpf_object name
+	 * in front. We still need to truncate them to 15 characters for the
+	 * kernel. Full name can be recovered for such maps by using DATASEC
+	 * BTF type associated with such map's value type, though.
+	 */
+	if (sfx_len >= BPF_OBJ_NAME_LEN)
+		sfx_len = BPF_OBJ_NAME_LEN - 1;
+
+	/* if there are two or more dots in map name, it's a custom dot map */
+	if (strchr(real_name + 1, '.') != NULL)
+		pfx_len = 0;
+	else
+		pfx_len = min((size_t)BPF_OBJ_NAME_LEN - sfx_len - 1, strlen(obj->name));
+
+	snprintf(map_name, sizeof(map_name), "%.*s%.*s", pfx_len, obj->name,
+		 sfx_len, real_name);
+
+	/* sanitise map name to characters allowed by kernel */
+	for (p = map_name; *p && p < map_name + sizeof(map_name); p++)
+		if (!isalnum(*p) && *p != '_' && *p != '.')
+			*p = '_';
+
+	return strdup(map_name);
+}
+
+static int
+map_fill_btf_type_info(struct bpf_object *obj, struct bpf_map *map);
+
+/* Internal BPF map is mmap()'able only if at least one of corresponding
+ * DATASEC's VARs are to be exposed through BPF skeleton. I.e., it's a GLOBAL
+ * variable and it's not marked as __hidden (which turns it into, effectively,
+ * a STATIC variable).
+ */
+static bool map_is_mmapable(struct bpf_object *obj, struct bpf_map *map)
+{
+	const struct btf_type *t, *vt;
+	struct btf_var_secinfo *vsi;
+	int i, n;
+
+	if (!map->btf_value_type_id)
+		return false;
+
+	t = btf__type_by_id(obj->btf, map->btf_value_type_id);
+	if (!btf_is_datasec(t))
+		return false;
+
+	vsi = btf_var_secinfos(t);
+	for (i = 0, n = btf_vlen(t); i < n; i++, vsi++) {
+		vt = btf__type_by_id(obj->btf, vsi->type);
+		if (!btf_is_var(vt))
+			continue;
+
+		if (btf_var(vt)->linkage != BTF_VAR_STATIC)
+			return true;
+	}
+
+	return false;
+}
+
+static int
+bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
+			      const char *real_name, int sec_idx, void *data, size_t data_sz)
+{
+	struct bpf_map_def *def;
+	struct bpf_map *map;
+	int err;
+
+	map = bpf_object__add_map(obj);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	map->libbpf_type = type;
+	map->sec_idx = sec_idx;
+	map->sec_offset = 0;
+	map->real_name = strdup(real_name);
+	map->name = internal_map_name(obj, real_name);
+	if (!map->real_name || !map->name) {
+		zfree(&map->real_name);
+		zfree(&map->name);
+		return -ENOMEM;
+	}
+
+	def = &map->def;
+	def->type = BPF_MAP_TYPE_ARRAY;
+	def->key_size = sizeof(int);
+	def->value_size = data_sz;
+	def->max_entries = 1;
+	def->map_flags = type == LIBBPF_MAP_RODATA || type == LIBBPF_MAP_KCONFIG
+			 ? BPF_F_RDONLY_PROG : 0;
+
+	/* failures are fine because of maps like .rodata.str1.1 */
+	(void) map_fill_btf_type_info(obj, map);
+
+	if (map_is_mmapable(obj, map))
+		def->map_flags |= BPF_F_MMAPABLE;
+
+	pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %x.\n",
+		 map->name, map->sec_idx, map->sec_offset, def->map_flags);
+
+	map->mmaped = mmap(NULL, bpf_map_mmap_sz(map), PROT_READ | PROT_WRITE,
+			   MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+	if (map->mmaped == MAP_FAILED) {
+		err = -errno;
+		map->mmaped = NULL;
+		pr_warn("failed to alloc map '%s' content buffer: %d\n",
+			map->name, err);
+		zfree(&map->real_name);
+		zfree(&map->name);
+		return err;
+	}
+
+	if (data)
+		memcpy(map->mmaped, data, data_sz);
+
+	pr_debug("map %td is \"%s\"\n", map - obj->maps, map->name);
+	return 0;
+}
+
+static int bpf_object__init_global_data_maps(struct bpf_object *obj)
+{
+	struct elf_sec_desc *sec_desc;
+	const char *sec_name;
+	int err = 0, sec_idx;
+
+	/*
+	 * Populate obj->maps with libbpf internal maps.
+	 */
+	for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) {
+		sec_desc = &obj->efile.secs[sec_idx];
+
+		/* Skip recognized sections with size 0. */
+		if (!sec_desc->data || sec_desc->data->d_size == 0)
+			continue;
+
+		switch (sec_desc->sec_type) {
+		case SEC_DATA:
+			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
+			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
+							    sec_name, sec_idx,
+							    sec_desc->data->d_buf,
+							    sec_desc->data->d_size);
+			break;
+		case SEC_RODATA:
+			obj->has_rodata = true;
+			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
+			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
+							    sec_name, sec_idx,
+							    sec_desc->data->d_buf,
+							    sec_desc->data->d_size);
+			break;
+		case SEC_BSS:
+			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
+			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
+							    sec_name, sec_idx,
+							    NULL,
+							    sec_desc->data->d_size);
+			break;
+		default:
+			/* skip */
+			break;
+		}
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+
+static struct extern_desc *find_extern_by_name(const struct bpf_object *obj,
+					       const void *name)
+{
+	int i;
+
+	for (i = 0; i < obj->nr_extern; i++) {
+		if (strcmp(obj->externs[i].name, name) == 0)
+			return &obj->externs[i];
+	}
+	return NULL;
+}
+
+static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val,
+			      char value)
+{
+	switch (ext->kcfg.type) {
+	case KCFG_BOOL:
+		if (value == 'm') {
+			pr_warn("extern (kcfg) '%s': value '%c' implies tristate or char type\n",
+				ext->name, value);
+			return -EINVAL;
+		}
+		*(bool *)ext_val = value == 'y' ? true : false;
+		break;
+	case KCFG_TRISTATE:
+		if (value == 'y')
+			*(enum libbpf_tristate *)ext_val = TRI_YES;
+		else if (value == 'm')
+			*(enum libbpf_tristate *)ext_val = TRI_MODULE;
+		else /* value == 'n' */
+			*(enum libbpf_tristate *)ext_val = TRI_NO;
+		break;
+	case KCFG_CHAR:
+		*(char *)ext_val = value;
+		break;
+	case KCFG_UNKNOWN:
+	case KCFG_INT:
+	case KCFG_CHAR_ARR:
+	default:
+		pr_warn("extern (kcfg) '%s': value '%c' implies bool, tristate, or char type\n",
+			ext->name, value);
+		return -EINVAL;
+	}
+	ext->is_set = true;
+	return 0;
+}
+
+static int set_kcfg_value_str(struct extern_desc *ext, char *ext_val,
+			      const char *value)
+{
+	size_t len;
+
+	if (ext->kcfg.type != KCFG_CHAR_ARR) {
+		pr_warn("extern (kcfg) '%s': value '%s' implies char array type\n",
+			ext->name, value);
+		return -EINVAL;
+	}
+
+	len = strlen(value);
+	if (value[len - 1] != '"') {
+		pr_warn("extern (kcfg) '%s': invalid string config '%s'\n",
+			ext->name, value);
+		return -EINVAL;
+	}
+
+	/* strip quotes */
+	len -= 2;
+	if (len >= ext->kcfg.sz) {
+		pr_warn("extern (kcfg) '%s': long string '%s' of (%zu bytes) truncated to %d bytes\n",
+			ext->name, value, len, ext->kcfg.sz - 1);
+		len = ext->kcfg.sz - 1;
+	}
+	memcpy(ext_val, value + 1, len);
+	ext_val[len] = '\0';
+	ext->is_set = true;
+	return 0;
+}
+
+static int parse_u64(const char *value, __u64 *res)
+{
+	char *value_end;
+	int err;
+
+	errno = 0;
+	*res = strtoull(value, &value_end, 0);
+	if (errno) {
+		err = -errno;
+		pr_warn("failed to parse '%s' as integer: %d\n", value, err);
+		return err;
+	}
+	if (*value_end) {
+		pr_warn("failed to parse '%s' as integer completely\n", value);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static bool is_kcfg_value_in_range(const struct extern_desc *ext, __u64 v)
+{
+	int bit_sz = ext->kcfg.sz * 8;
+
+	if (ext->kcfg.sz == 8)
+		return true;
+
+	/* Validate that value stored in u64 fits in integer of `ext->sz`
+	 * bytes size without any loss of information. If the target integer
+	 * is signed, we rely on the following limits of integer type of
+	 * Y bits and subsequent transformation:
+	 *
+	 *     -2^(Y-1) <= X           <= 2^(Y-1) - 1
+	 *            0 <= X + 2^(Y-1) <= 2^Y - 1
+	 *            0 <= X + 2^(Y-1) <  2^Y
+	 *
+	 *  For unsigned target integer, check that all the (64 - Y) bits are
+	 *  zero.
+	 */
+	if (ext->kcfg.is_signed)
+		return v + (1ULL << (bit_sz - 1)) < (1ULL << bit_sz);
+	else
+		return (v >> bit_sz) == 0;
+}
+
+static int set_kcfg_value_num(struct extern_desc *ext, void *ext_val,
+			      __u64 value)
+{
+	if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR &&
+	    ext->kcfg.type != KCFG_BOOL) {
+		pr_warn("extern (kcfg) '%s': value '%llu' implies integer, char, or boolean type\n",
+			ext->name, (unsigned long long)value);
+		return -EINVAL;
+	}
+	if (ext->kcfg.type == KCFG_BOOL && value > 1) {
+		pr_warn("extern (kcfg) '%s': value '%llu' isn't boolean compatible\n",
+			ext->name, (unsigned long long)value);
+		return -EINVAL;
+
+	}
+	if (!is_kcfg_value_in_range(ext, value)) {
+		pr_warn("extern (kcfg) '%s': value '%llu' doesn't fit in %d bytes\n",
+			ext->name, (unsigned long long)value, ext->kcfg.sz);
+		return -ERANGE;
+	}
+	switch (ext->kcfg.sz) {
+	case 1:
+		*(__u8 *)ext_val = value;
+		break;
+	case 2:
+		*(__u16 *)ext_val = value;
+		break;
+	case 4:
+		*(__u32 *)ext_val = value;
+		break;
+	case 8:
+		*(__u64 *)ext_val = value;
+		break;
+	default:
+		return -EINVAL;
+	}
+	ext->is_set = true;
+	return 0;
+}
+
+static int bpf_object__process_kconfig_line(struct bpf_object *obj,
+					    char *buf, void *data)
+{
+	struct extern_desc *ext;
+	char *sep, *value;
+	int len, err = 0;
+	void *ext_val;
+	__u64 num;
+
+	if (!str_has_pfx(buf, "CONFIG_"))
+		return 0;
+
+	sep = strchr(buf, '=');
+	if (!sep) {
+		pr_warn("failed to parse '%s': no separator\n", buf);
+		return -EINVAL;
+	}
+
+	/* Trim ending '\n' */
+	len = strlen(buf);
+	if (buf[len - 1] == '\n')
+		buf[len - 1] = '\0';
+	/* Split on '=' and ensure that a value is present. */
+	*sep = '\0';
+	if (!sep[1]) {
+		*sep = '=';
+		pr_warn("failed to parse '%s': no value\n", buf);
+		return -EINVAL;
+	}
+
+	ext = find_extern_by_name(obj, buf);
+	if (!ext || ext->is_set)
+		return 0;
+
+	ext_val = data + ext->kcfg.data_off;
+	value = sep + 1;
+
+	switch (*value) {
+	case 'y': case 'n': case 'm':
+		err = set_kcfg_value_tri(ext, ext_val, *value);
+		break;
+	case '"':
+		err = set_kcfg_value_str(ext, ext_val, value);
+		break;
+	default:
+		/* assume integer */
+		err = parse_u64(value, &num);
+		if (err) {
+			pr_warn("extern (kcfg) '%s': value '%s' isn't a valid integer\n", ext->name, value);
+			return err;
+		}
+		if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR) {
+			pr_warn("extern (kcfg) '%s': value '%s' implies integer type\n", ext->name, value);
+			return -EINVAL;
+		}
+		err = set_kcfg_value_num(ext, ext_val, num);
+		break;
+	}
+	if (err)
+		return err;
+	pr_debug("extern (kcfg) '%s': set to %s\n", ext->name, value);
+	return 0;
+}
+
+static int bpf_object__read_kconfig_file(struct bpf_object *obj, void *data)
+{
+	char buf[PATH_MAX];
+	struct utsname uts;
+	int len, err = 0;
+	gzFile file;
+
+	uname(&uts);
+	len = snprintf(buf, PATH_MAX, "/boot/config-%s", uts.release);
+	if (len < 0)
+		return -EINVAL;
+	else if (len >= PATH_MAX)
+		return -ENAMETOOLONG;
+
+	/* gzopen also accepts uncompressed files. */
+	file = gzopen(buf, "r");
+	if (!file)
+		file = gzopen("/proc/config.gz", "r");
+
+	if (!file) {
+		pr_warn("failed to open system Kconfig\n");
+		return -ENOENT;
+	}
+
+	while (gzgets(file, buf, sizeof(buf))) {
+		err = bpf_object__process_kconfig_line(obj, buf, data);
+		if (err) {
+			pr_warn("error parsing system Kconfig line '%s': %d\n",
+				buf, err);
+			goto out;
+		}
+	}
+
+out:
+	gzclose(file);
+	return err;
+}
+
+static int bpf_object__read_kconfig_mem(struct bpf_object *obj,
+					const char *config, void *data)
+{
+	char buf[PATH_MAX];
+	int err = 0;
+	FILE *file;
+
+	file = fmemopen((void *)config, strlen(config), "r");
+	if (!file) {
+		err = -errno;
+		pr_warn("failed to open in-memory Kconfig: %d\n", err);
+		return err;
+	}
+
+	while (fgets(buf, sizeof(buf), file)) {
+		err = bpf_object__process_kconfig_line(obj, buf, data);
+		if (err) {
+			pr_warn("error parsing in-memory Kconfig line '%s': %d\n",
+				buf, err);
+			break;
+		}
+	}
+
+	fclose(file);
+	return err;
+}
+
+static int bpf_object__init_kconfig_map(struct bpf_object *obj)
+{
+	struct extern_desc *last_ext = NULL, *ext;
+	size_t map_sz;
+	int i, err;
+
+	for (i = 0; i < obj->nr_extern; i++) {
+		ext = &obj->externs[i];
+		if (ext->type == EXT_KCFG)
+			last_ext = ext;
+	}
+
+	if (!last_ext)
+		return 0;
+
+	map_sz = last_ext->kcfg.data_off + last_ext->kcfg.sz;
+	err = bpf_object__init_internal_map(obj, LIBBPF_MAP_KCONFIG,
+					    ".kconfig", obj->efile.symbols_shndx,
+					    NULL, map_sz);
+	if (err)
+		return err;
+
+	obj->kconfig_map_idx = obj->nr_maps - 1;
+
+	return 0;
+}
+
+const struct btf_type *
+skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
+{
+	const struct btf_type *t = btf__type_by_id(btf, id);
+
+	if (res_id)
+		*res_id = id;
+
+	while (btf_is_mod(t) || btf_is_typedef(t)) {
+		if (res_id)
+			*res_id = t->type;
+		t = btf__type_by_id(btf, t->type);
+	}
+
+	return t;
+}
+
+static const struct btf_type *
+resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
+{
+	const struct btf_type *t;
+
+	t = skip_mods_and_typedefs(btf, id, NULL);
+	if (!btf_is_ptr(t))
+		return NULL;
+
+	t = skip_mods_and_typedefs(btf, t->type, res_id);
+
+	return btf_is_func_proto(t) ? t : NULL;
+}
+
+static const char *__btf_kind_str(__u16 kind)
+{
+	switch (kind) {
+	case BTF_KIND_UNKN: return "void";
+	case BTF_KIND_INT: return "int";
+	case BTF_KIND_PTR: return "ptr";
+	case BTF_KIND_ARRAY: return "array";
+	case BTF_KIND_STRUCT: return "struct";
+	case BTF_KIND_UNION: return "union";
+	case BTF_KIND_ENUM: return "enum";
+	case BTF_KIND_FWD: return "fwd";
+	case BTF_KIND_TYPEDEF: return "typedef";
+	case BTF_KIND_VOLATILE: return "volatile";
+	case BTF_KIND_CONST: return "const";
+	case BTF_KIND_RESTRICT: return "restrict";
+	case BTF_KIND_FUNC: return "func";
+	case BTF_KIND_FUNC_PROTO: return "func_proto";
+	case BTF_KIND_VAR: return "var";
+	case BTF_KIND_DATASEC: return "datasec";
+	case BTF_KIND_FLOAT: return "float";
+	case BTF_KIND_DECL_TAG: return "decl_tag";
+	case BTF_KIND_TYPE_TAG: return "type_tag";
+	case BTF_KIND_ENUM64: return "enum64";
+	default: return "unknown";
+	}
+}
+
+const char *btf_kind_str(const struct btf_type *t)
+{
+	return __btf_kind_str(btf_kind(t));
+}
+
+/*
+ * Fetch integer attribute of BTF map definition. Such attributes are
+ * represented using a pointer to an array, in which dimensionality of array
+ * encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY];
+ * encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF
+ * type definition, while using only sizeof(void *) space in ELF data section.
+ */
+static bool get_map_field_int(const char *map_name, const struct btf *btf,
+			      const struct btf_member *m, __u32 *res)
+{
+	const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL);
+	const char *name = btf__name_by_offset(btf, m->name_off);
+	const struct btf_array *arr_info;
+	const struct btf_type *arr_t;
+
+	if (!btf_is_ptr(t)) {
+		pr_warn("map '%s': attr '%s': expected PTR, got %s.\n",
+			map_name, name, btf_kind_str(t));
+		return false;
+	}
+
+	arr_t = btf__type_by_id(btf, t->type);
+	if (!arr_t) {
+		pr_warn("map '%s': attr '%s': type [%u] not found.\n",
+			map_name, name, t->type);
+		return false;
+	}
+	if (!btf_is_array(arr_t)) {
+		pr_warn("map '%s': attr '%s': expected ARRAY, got %s.\n",
+			map_name, name, btf_kind_str(arr_t));
+		return false;
+	}
+	arr_info = btf_array(arr_t);
+	*res = arr_info->nelems;
+	return true;
+}
+
+static int pathname_concat(char *buf, size_t buf_sz, const char *path, const char *name)
+{
+	int len;
+
+	len = snprintf(buf, buf_sz, "%s/%s", path, name);
+	if (len < 0)
+		return -EINVAL;
+	if (len >= buf_sz)
+		return -ENAMETOOLONG;
+
+	return 0;
+}
+
+static int build_map_pin_path(struct bpf_map *map, const char *path)
+{
+	char buf[PATH_MAX];
+	int err;
+
+	if (!path)
+		path = "/sys/fs/bpf";
+
+	err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
+	if (err)
+		return err;
+
+	return bpf_map__set_pin_path(map, buf);
+}
+
+/* should match definition in bpf_helpers.h */
+enum libbpf_pin_type {
+	LIBBPF_PIN_NONE,
+	/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
+	LIBBPF_PIN_BY_NAME,
+};
+
+int parse_btf_map_def(const char *map_name, struct btf *btf,
+		      const struct btf_type *def_t, bool strict,
+		      struct btf_map_def *map_def, struct btf_map_def *inner_def)
+{
+	const struct btf_type *t;
+	const struct btf_member *m;
+	bool is_inner = inner_def == NULL;
+	int vlen, i;
+
+	vlen = btf_vlen(def_t);
+	m = btf_members(def_t);
+	for (i = 0; i < vlen; i++, m++) {
+		const char *name = btf__name_by_offset(btf, m->name_off);
+
+		if (!name) {
+			pr_warn("map '%s': invalid field #%d.\n", map_name, i);
+			return -EINVAL;
+		}
+		if (strcmp(name, "type") == 0) {
+			if (!get_map_field_int(map_name, btf, m, &map_def->map_type))
+				return -EINVAL;
+			map_def->parts |= MAP_DEF_MAP_TYPE;
+		} else if (strcmp(name, "max_entries") == 0) {
+			if (!get_map_field_int(map_name, btf, m, &map_def->max_entries))
+				return -EINVAL;
+			map_def->parts |= MAP_DEF_MAX_ENTRIES;
+		} else if (strcmp(name, "map_flags") == 0) {
+			if (!get_map_field_int(map_name, btf, m, &map_def->map_flags))
+				return -EINVAL;
+			map_def->parts |= MAP_DEF_MAP_FLAGS;
+		} else if (strcmp(name, "numa_node") == 0) {
+			if (!get_map_field_int(map_name, btf, m, &map_def->numa_node))
+				return -EINVAL;
+			map_def->parts |= MAP_DEF_NUMA_NODE;
+		} else if (strcmp(name, "key_size") == 0) {
+			__u32 sz;
+
+			if (!get_map_field_int(map_name, btf, m, &sz))
+				return -EINVAL;
+			if (map_def->key_size && map_def->key_size != sz) {
+				pr_warn("map '%s': conflicting key size %u != %u.\n",
+					map_name, map_def->key_size, sz);
+				return -EINVAL;
+			}
+			map_def->key_size = sz;
+			map_def->parts |= MAP_DEF_KEY_SIZE;
+		} else if (strcmp(name, "key") == 0) {
+			__s64 sz;
+
+			t = btf__type_by_id(btf, m->type);
+			if (!t) {
+				pr_warn("map '%s': key type [%d] not found.\n",
+					map_name, m->type);
+				return -EINVAL;
+			}
+			if (!btf_is_ptr(t)) {
+				pr_warn("map '%s': key spec is not PTR: %s.\n",
+					map_name, btf_kind_str(t));
+				return -EINVAL;
+			}
+			sz = btf__resolve_size(btf, t->type);
+			if (sz < 0) {
+				pr_warn("map '%s': can't determine key size for type [%u]: %zd.\n",
+					map_name, t->type, (ssize_t)sz);
+				return sz;
+			}
+			if (map_def->key_size && map_def->key_size != sz) {
+				pr_warn("map '%s': conflicting key size %u != %zd.\n",
+					map_name, map_def->key_size, (ssize_t)sz);
+				return -EINVAL;
+			}
+			map_def->key_size = sz;
+			map_def->key_type_id = t->type;
+			map_def->parts |= MAP_DEF_KEY_SIZE | MAP_DEF_KEY_TYPE;
+		} else if (strcmp(name, "value_size") == 0) {
+			__u32 sz;
+
+			if (!get_map_field_int(map_name, btf, m, &sz))
+				return -EINVAL;
+			if (map_def->value_size && map_def->value_size != sz) {
+				pr_warn("map '%s': conflicting value size %u != %u.\n",
+					map_name, map_def->value_size, sz);
+				return -EINVAL;
+			}
+			map_def->value_size = sz;
+			map_def->parts |= MAP_DEF_VALUE_SIZE;
+		} else if (strcmp(name, "value") == 0) {
+			__s64 sz;
+
+			t = btf__type_by_id(btf, m->type);
+			if (!t) {
+				pr_warn("map '%s': value type [%d] not found.\n",
+					map_name, m->type);
+				return -EINVAL;
+			}
+			if (!btf_is_ptr(t)) {
+				pr_warn("map '%s': value spec is not PTR: %s.\n",
+					map_name, btf_kind_str(t));
+				return -EINVAL;
+			}
+			sz = btf__resolve_size(btf, t->type);
+			if (sz < 0) {
+				pr_warn("map '%s': can't determine value size for type [%u]: %zd.\n",
+					map_name, t->type, (ssize_t)sz);
+				return sz;
+			}
+			if (map_def->value_size && map_def->value_size != sz) {
+				pr_warn("map '%s': conflicting value size %u != %zd.\n",
+					map_name, map_def->value_size, (ssize_t)sz);
+				return -EINVAL;
+			}
+			map_def->value_size = sz;
+			map_def->value_type_id = t->type;
+			map_def->parts |= MAP_DEF_VALUE_SIZE | MAP_DEF_VALUE_TYPE;
+		}
+		else if (strcmp(name, "values") == 0) {
+			bool is_map_in_map = bpf_map_type__is_map_in_map(map_def->map_type);
+			bool is_prog_array = map_def->map_type == BPF_MAP_TYPE_PROG_ARRAY;
+			const char *desc = is_map_in_map ? "map-in-map inner" : "prog-array value";
+			char inner_map_name[128];
+			int err;
+
+			if (is_inner) {
+				pr_warn("map '%s': multi-level inner maps not supported.\n",
+					map_name);
+				return -ENOTSUP;
+			}
+			if (i != vlen - 1) {
+				pr_warn("map '%s': '%s' member should be last.\n",
+					map_name, name);
+				return -EINVAL;
+			}
+			if (!is_map_in_map && !is_prog_array) {
+				pr_warn("map '%s': should be map-in-map or prog-array.\n",
+					map_name);
+				return -ENOTSUP;
+			}
+			if (map_def->value_size && map_def->value_size != 4) {
+				pr_warn("map '%s': conflicting value size %u != 4.\n",
+					map_name, map_def->value_size);
+				return -EINVAL;
+			}
+			map_def->value_size = 4;
+			t = btf__type_by_id(btf, m->type);
+			if (!t) {
+				pr_warn("map '%s': %s type [%d] not found.\n",
+					map_name, desc, m->type);
+				return -EINVAL;
+			}
+			if (!btf_is_array(t) || btf_array(t)->nelems) {
+				pr_warn("map '%s': %s spec is not a zero-sized array.\n",
+					map_name, desc);
+				return -EINVAL;
+			}
+			t = skip_mods_and_typedefs(btf, btf_array(t)->type, NULL);
+			if (!btf_is_ptr(t)) {
+				pr_warn("map '%s': %s def is of unexpected kind %s.\n",
+					map_name, desc, btf_kind_str(t));
+				return -EINVAL;
+			}
+			t = skip_mods_and_typedefs(btf, t->type, NULL);
+			if (is_prog_array) {
+				if (!btf_is_func_proto(t)) {
+					pr_warn("map '%s': prog-array value def is of unexpected kind %s.\n",
+						map_name, btf_kind_str(t));
+					return -EINVAL;
+				}
+				continue;
+			}
+			if (!btf_is_struct(t)) {
+				pr_warn("map '%s': map-in-map inner def is of unexpected kind %s.\n",
+					map_name, btf_kind_str(t));
+				return -EINVAL;
+			}
+
+			snprintf(inner_map_name, sizeof(inner_map_name), "%s.inner", map_name);
+			err = parse_btf_map_def(inner_map_name, btf, t, strict, inner_def, NULL);
+			if (err)
+				return err;
+
+			map_def->parts |= MAP_DEF_INNER_MAP;
+		} else if (strcmp(name, "pinning") == 0) {
+			__u32 val;
+
+			if (is_inner) {
+				pr_warn("map '%s': inner def can't be pinned.\n", map_name);
+				return -EINVAL;
+			}
+			if (!get_map_field_int(map_name, btf, m, &val))
+				return -EINVAL;
+			if (val != LIBBPF_PIN_NONE && val != LIBBPF_PIN_BY_NAME) {
+				pr_warn("map '%s': invalid pinning value %u.\n",
+					map_name, val);
+				return -EINVAL;
+			}
+			map_def->pinning = val;
+			map_def->parts |= MAP_DEF_PINNING;
+		} else if (strcmp(name, "map_extra") == 0) {
+			__u32 map_extra;
+
+			if (!get_map_field_int(map_name, btf, m, &map_extra))
+				return -EINVAL;
+			map_def->map_extra = map_extra;
+			map_def->parts |= MAP_DEF_MAP_EXTRA;
+		} else {
+			if (strict) {
+				pr_warn("map '%s': unknown field '%s'.\n", map_name, name);
+				return -ENOTSUP;
+			}
+			pr_debug("map '%s': ignoring unknown field '%s'.\n", map_name, name);
+		}
+	}
+
+	if (map_def->map_type == BPF_MAP_TYPE_UNSPEC) {
+		pr_warn("map '%s': map type isn't specified.\n", map_name);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static size_t adjust_ringbuf_sz(size_t sz)
+{
+	__u32 page_sz = sysconf(_SC_PAGE_SIZE);
+	__u32 mul;
+
+	/* if user forgot to set any size, make sure they see error */
+	if (sz == 0)
+		return 0;
+	/* Kernel expects BPF_MAP_TYPE_RINGBUF's max_entries to be
+	 * a power-of-2 multiple of kernel's page size. If user diligently
+	 * satisified these conditions, pass the size through.
+	 */
+	if ((sz % page_sz) == 0 && is_pow_of_2(sz / page_sz))
+		return sz;
+
+	/* Otherwise find closest (page_sz * power_of_2) product bigger than
+	 * user-set size to satisfy both user size request and kernel
+	 * requirements and substitute correct max_entries for map creation.
+	 */
+	for (mul = 1; mul <= UINT_MAX / page_sz; mul <<= 1) {
+		if (mul * page_sz > sz)
+			return mul * page_sz;
+	}
+
+	/* if it's impossible to satisfy the conditions (i.e., user size is
+	 * very close to UINT_MAX but is not a power-of-2 multiple of
+	 * page_size) then just return original size and let kernel reject it
+	 */
+	return sz;
+}
+
+static bool map_is_ringbuf(const struct bpf_map *map)
+{
+	return map->def.type == BPF_MAP_TYPE_RINGBUF ||
+	       map->def.type == BPF_MAP_TYPE_USER_RINGBUF;
+}
+
+static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def)
+{
+	map->def.type = def->map_type;
+	map->def.key_size = def->key_size;
+	map->def.value_size = def->value_size;
+	map->def.max_entries = def->max_entries;
+	map->def.map_flags = def->map_flags;
+	map->map_extra = def->map_extra;
+
+	map->numa_node = def->numa_node;
+	map->btf_key_type_id = def->key_type_id;
+	map->btf_value_type_id = def->value_type_id;
+
+	/* auto-adjust BPF ringbuf map max_entries to be a multiple of page size */
+	if (map_is_ringbuf(map))
+		map->def.max_entries = adjust_ringbuf_sz(map->def.max_entries);
+
+	if (def->parts & MAP_DEF_MAP_TYPE)
+		pr_debug("map '%s': found type = %u.\n", map->name, def->map_type);
+
+	if (def->parts & MAP_DEF_KEY_TYPE)
+		pr_debug("map '%s': found key [%u], sz = %u.\n",
+			 map->name, def->key_type_id, def->key_size);
+	else if (def->parts & MAP_DEF_KEY_SIZE)
+		pr_debug("map '%s': found key_size = %u.\n", map->name, def->key_size);
+
+	if (def->parts & MAP_DEF_VALUE_TYPE)
+		pr_debug("map '%s': found value [%u], sz = %u.\n",
+			 map->name, def->value_type_id, def->value_size);
+	else if (def->parts & MAP_DEF_VALUE_SIZE)
+		pr_debug("map '%s': found value_size = %u.\n", map->name, def->value_size);
+
+	if (def->parts & MAP_DEF_MAX_ENTRIES)
+		pr_debug("map '%s': found max_entries = %u.\n", map->name, def->max_entries);
+	if (def->parts & MAP_DEF_MAP_FLAGS)
+		pr_debug("map '%s': found map_flags = 0x%x.\n", map->name, def->map_flags);
+	if (def->parts & MAP_DEF_MAP_EXTRA)
+		pr_debug("map '%s': found map_extra = 0x%llx.\n", map->name,
+			 (unsigned long long)def->map_extra);
+	if (def->parts & MAP_DEF_PINNING)
+		pr_debug("map '%s': found pinning = %u.\n", map->name, def->pinning);
+	if (def->parts & MAP_DEF_NUMA_NODE)
+		pr_debug("map '%s': found numa_node = %u.\n", map->name, def->numa_node);
+
+	if (def->parts & MAP_DEF_INNER_MAP)
+		pr_debug("map '%s': found inner map definition.\n", map->name);
+}
+
+static const char *btf_var_linkage_str(__u32 linkage)
+{
+	switch (linkage) {
+	case BTF_VAR_STATIC: return "static";
+	case BTF_VAR_GLOBAL_ALLOCATED: return "global";
+	case BTF_VAR_GLOBAL_EXTERN: return "extern";
+	default: return "unknown";
+	}
+}
+
+static int bpf_object__init_user_btf_map(struct bpf_object *obj,
+					 const struct btf_type *sec,
+					 int var_idx, int sec_idx,
+					 const Elf_Data *data, bool strict,
+					 const char *pin_root_path)
+{
+	struct btf_map_def map_def = {}, inner_def = {};
+	const struct btf_type *var, *def;
+	const struct btf_var_secinfo *vi;
+	const struct btf_var *var_extra;
+	const char *map_name;
+	struct bpf_map *map;
+	int err;
+
+	vi = btf_var_secinfos(sec) + var_idx;
+	var = btf__type_by_id(obj->btf, vi->type);
+	var_extra = btf_var(var);
+	map_name = btf__name_by_offset(obj->btf, var->name_off);
+
+	if (map_name == NULL || map_name[0] == '\0') {
+		pr_warn("map #%d: empty name.\n", var_idx);
+		return -EINVAL;
+	}
+	if ((__u64)vi->offset + vi->size > data->d_size) {
+		pr_warn("map '%s' BTF data is corrupted.\n", map_name);
+		return -EINVAL;
+	}
+	if (!btf_is_var(var)) {
+		pr_warn("map '%s': unexpected var kind %s.\n",
+			map_name, btf_kind_str(var));
+		return -EINVAL;
+	}
+	if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED) {
+		pr_warn("map '%s': unsupported map linkage %s.\n",
+			map_name, btf_var_linkage_str(var_extra->linkage));
+		return -EOPNOTSUPP;
+	}
+
+	def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
+	if (!btf_is_struct(def)) {
+		pr_warn("map '%s': unexpected def kind %s.\n",
+			map_name, btf_kind_str(var));
+		return -EINVAL;
+	}
+	if (def->size > vi->size) {
+		pr_warn("map '%s': invalid def size.\n", map_name);
+		return -EINVAL;
+	}
+
+	map = bpf_object__add_map(obj);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+	map->name = strdup(map_name);
+	if (!map->name) {
+		pr_warn("map '%s': failed to alloc map name.\n", map_name);
+		return -ENOMEM;
+	}
+	map->libbpf_type = LIBBPF_MAP_UNSPEC;
+	map->def.type = BPF_MAP_TYPE_UNSPEC;
+	map->sec_idx = sec_idx;
+	map->sec_offset = vi->offset;
+	map->btf_var_idx = var_idx;
+	pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
+		 map_name, map->sec_idx, map->sec_offset);
+
+	err = parse_btf_map_def(map->name, obj->btf, def, strict, &map_def, &inner_def);
+	if (err)
+		return err;
+
+	fill_map_from_def(map, &map_def);
+
+	if (map_def.pinning == LIBBPF_PIN_BY_NAME) {
+		err = build_map_pin_path(map, pin_root_path);
+		if (err) {
+			pr_warn("map '%s': couldn't build pin path.\n", map->name);
+			return err;
+		}
+	}
+
+	if (map_def.parts & MAP_DEF_INNER_MAP) {
+		map->inner_map = calloc(1, sizeof(*map->inner_map));
+		if (!map->inner_map)
+			return -ENOMEM;
+		map->inner_map->fd = -1;
+		map->inner_map->sec_idx = sec_idx;
+		map->inner_map->name = malloc(strlen(map_name) + sizeof(".inner") + 1);
+		if (!map->inner_map->name)
+			return -ENOMEM;
+		sprintf(map->inner_map->name, "%s.inner", map_name);
+
+		fill_map_from_def(map->inner_map, &inner_def);
+	}
+
+	err = map_fill_btf_type_info(obj, map);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
+					  const char *pin_root_path)
+{
+	const struct btf_type *sec = NULL;
+	int nr_types, i, vlen, err;
+	const struct btf_type *t;
+	const char *name;
+	Elf_Data *data;
+	Elf_Scn *scn;
+
+	if (obj->efile.btf_maps_shndx < 0)
+		return 0;
+
+	scn = elf_sec_by_idx(obj, obj->efile.btf_maps_shndx);
+	data = elf_sec_data(obj, scn);
+	if (!scn || !data) {
+		pr_warn("elf: failed to get %s map definitions for %s\n",
+			MAPS_ELF_SEC, obj->path);
+		return -EINVAL;
+	}
+
+	nr_types = btf__type_cnt(obj->btf);
+	for (i = 1; i < nr_types; i++) {
+		t = btf__type_by_id(obj->btf, i);
+		if (!btf_is_datasec(t))
+			continue;
+		name = btf__name_by_offset(obj->btf, t->name_off);
+		if (strcmp(name, MAPS_ELF_SEC) == 0) {
+			sec = t;
+			obj->efile.btf_maps_sec_btf_id = i;
+			break;
+		}
+	}
+
+	if (!sec) {
+		pr_warn("DATASEC '%s' not found.\n", MAPS_ELF_SEC);
+		return -ENOENT;
+	}
+
+	vlen = btf_vlen(sec);
+	for (i = 0; i < vlen; i++) {
+		err = bpf_object__init_user_btf_map(obj, sec, i,
+						    obj->efile.btf_maps_shndx,
+						    data, strict,
+						    pin_root_path);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int bpf_object__init_maps(struct bpf_object *obj,
+				 const struct bpf_object_open_opts *opts)
+{
+	const char *pin_root_path;
+	bool strict;
+	int err = 0;
+
+	strict = !OPTS_GET(opts, relaxed_maps, false);
+	pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
+
+	err = err ?: bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
+	err = err ?: bpf_object__init_global_data_maps(obj);
+	err = err ?: bpf_object__init_kconfig_map(obj);
+	err = err ?: bpf_object__init_struct_ops_maps(obj);
+
+	return err;
+}
+
+static bool section_have_execinstr(struct bpf_object *obj, int idx)
+{
+	Elf64_Shdr *sh;
+
+	sh = elf_sec_hdr(obj, elf_sec_by_idx(obj, idx));
+	if (!sh)
+		return false;
+
+	return sh->sh_flags & SHF_EXECINSTR;
+}
+
+static bool btf_needs_sanitization(struct bpf_object *obj)
+{
+	bool has_func_global = kernel_supports(obj, FEAT_BTF_GLOBAL_FUNC);
+	bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
+	bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
+	bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
+	bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
+	bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
+	bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64);
+
+	return !has_func || !has_datasec || !has_func_global || !has_float ||
+	       !has_decl_tag || !has_type_tag || !has_enum64;
+}
+
+static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
+{
+	bool has_func_global = kernel_supports(obj, FEAT_BTF_GLOBAL_FUNC);
+	bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
+	bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
+	bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
+	bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
+	bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
+	bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64);
+	int enum64_placeholder_id = 0;
+	struct btf_type *t;
+	int i, j, vlen;
+
+	for (i = 1; i < btf__type_cnt(btf); i++) {
+		t = (struct btf_type *)btf__type_by_id(btf, i);
+
+		if ((!has_datasec && btf_is_var(t)) || (!has_decl_tag && btf_is_decl_tag(t))) {
+			/* replace VAR/DECL_TAG with INT */
+			t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
+			/*
+			 * using size = 1 is the safest choice, 4 will be too
+			 * big and cause kernel BTF validation failure if
+			 * original variable took less than 4 bytes
+			 */
+			t->size = 1;
+			*(int *)(t + 1) = BTF_INT_ENC(0, 0, 8);
+		} else if (!has_datasec && btf_is_datasec(t)) {
+			/* replace DATASEC with STRUCT */
+			const struct btf_var_secinfo *v = btf_var_secinfos(t);
+			struct btf_member *m = btf_members(t);
+			struct btf_type *vt;
+			char *name;
+
+			name = (char *)btf__name_by_offset(btf, t->name_off);
+			while (*name) {
+				if (*name == '.')
+					*name = '_';
+				name++;
+			}
+
+			vlen = btf_vlen(t);
+			t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, vlen);
+			for (j = 0; j < vlen; j++, v++, m++) {
+				/* order of field assignments is important */
+				m->offset = v->offset * 8;
+				m->type = v->type;
+				/* preserve variable name as member name */
+				vt = (void *)btf__type_by_id(btf, v->type);
+				m->name_off = vt->name_off;
+			}
+		} else if (!has_func && btf_is_func_proto(t)) {
+			/* replace FUNC_PROTO with ENUM */
+			vlen = btf_vlen(t);
+			t->info = BTF_INFO_ENC(BTF_KIND_ENUM, 0, vlen);
+			t->size = sizeof(__u32); /* kernel enforced */
+		} else if (!has_func && btf_is_func(t)) {
+			/* replace FUNC with TYPEDEF */
+			t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0);
+		} else if (!has_func_global && btf_is_func(t)) {
+			/* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
+			t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
+		} else if (!has_float && btf_is_float(t)) {
+			/* replace FLOAT with an equally-sized empty STRUCT;
+			 * since C compilers do not accept e.g. "float" as a
+			 * valid struct name, make it anonymous
+			 */
+			t->name_off = 0;
+			t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0);
+		} else if (!has_type_tag && btf_is_type_tag(t)) {
+			/* replace TYPE_TAG with a CONST */
+			t->name_off = 0;
+			t->info = BTF_INFO_ENC(BTF_KIND_CONST, 0, 0);
+		} else if (!has_enum64 && btf_is_enum(t)) {
+			/* clear the kflag */
+			t->info = btf_type_info(btf_kind(t), btf_vlen(t), false);
+		} else if (!has_enum64 && btf_is_enum64(t)) {
+			/* replace ENUM64 with a union */
+			struct btf_member *m;
+
+			if (enum64_placeholder_id == 0) {
+				enum64_placeholder_id = btf__add_int(btf, "enum64_placeholder", 1, 0);
+				if (enum64_placeholder_id < 0)
+					return enum64_placeholder_id;
+
+				t = (struct btf_type *)btf__type_by_id(btf, i);
+			}
+
+			m = btf_members(t);
+			vlen = btf_vlen(t);
+			t->info = BTF_INFO_ENC(BTF_KIND_UNION, 0, vlen);
+			for (j = 0; j < vlen; j++, m++) {
+				m->type = enum64_placeholder_id;
+				m->offset = 0;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static bool libbpf_needs_btf(const struct bpf_object *obj)
+{
+	return obj->efile.btf_maps_shndx >= 0 ||
+	       obj->efile.st_ops_shndx >= 0 ||
+	       obj->nr_extern > 0;
+}
+
+static bool kernel_needs_btf(const struct bpf_object *obj)
+{
+	return obj->efile.st_ops_shndx >= 0;
+}
+
+static int bpf_object__init_btf(struct bpf_object *obj,
+				Elf_Data *btf_data,
+				Elf_Data *btf_ext_data)
+{
+	int err = -ENOENT;
+
+	if (btf_data) {
+		obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
+		err = libbpf_get_error(obj->btf);
+		if (err) {
+			obj->btf = NULL;
+			pr_warn("Error loading ELF section %s: %d.\n", BTF_ELF_SEC, err);
+			goto out;
+		}
+		/* enforce 8-byte pointers for BPF-targeted BTFs */
+		btf__set_pointer_size(obj->btf, 8);
+	}
+	if (btf_ext_data) {
+		struct btf_ext_info *ext_segs[3];
+		int seg_num, sec_num;
+
+		if (!obj->btf) {
+			pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
+				 BTF_EXT_ELF_SEC, BTF_ELF_SEC);
+			goto out;
+		}
+		obj->btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
+		err = libbpf_get_error(obj->btf_ext);
+		if (err) {
+			pr_warn("Error loading ELF section %s: %d. Ignored and continue.\n",
+				BTF_EXT_ELF_SEC, err);
+			obj->btf_ext = NULL;
+			goto out;
+		}
+
+		/* setup .BTF.ext to ELF section mapping */
+		ext_segs[0] = &obj->btf_ext->func_info;
+		ext_segs[1] = &obj->btf_ext->line_info;
+		ext_segs[2] = &obj->btf_ext->core_relo_info;
+		for (seg_num = 0; seg_num < ARRAY_SIZE(ext_segs); seg_num++) {
+			struct btf_ext_info *seg = ext_segs[seg_num];
+			const struct btf_ext_info_sec *sec;
+			const char *sec_name;
+			Elf_Scn *scn;
+
+			if (seg->sec_cnt == 0)
+				continue;
+
+			seg->sec_idxs = calloc(seg->sec_cnt, sizeof(*seg->sec_idxs));
+			if (!seg->sec_idxs) {
+				err = -ENOMEM;
+				goto out;
+			}
+
+			sec_num = 0;
+			for_each_btf_ext_sec(seg, sec) {
+				/* preventively increment index to avoid doing
+				 * this before every continue below
+				 */
+				sec_num++;
+
+				sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
+				if (str_is_empty(sec_name))
+					continue;
+				scn = elf_sec_by_name(obj, sec_name);
+				if (!scn)
+					continue;
+
+				seg->sec_idxs[sec_num - 1] = elf_ndxscn(scn);
+			}
+		}
+	}
+out:
+	if (err && libbpf_needs_btf(obj)) {
+		pr_warn("BTF is required, but is missing or corrupted.\n");
+		return err;
+	}
+	return 0;
+}
+
+static int compare_vsi_off(const void *_a, const void *_b)
+{
+	const struct btf_var_secinfo *a = _a;
+	const struct btf_var_secinfo *b = _b;
+
+	return a->offset - b->offset;
+}
+
+static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
+			     struct btf_type *t)
+{
+	__u32 size = 0, i, vars = btf_vlen(t);
+	const char *sec_name = btf__name_by_offset(btf, t->name_off);
+	struct btf_var_secinfo *vsi;
+	bool fixup_offsets = false;
+	int err;
+
+	if (!sec_name) {
+		pr_debug("No name found in string section for DATASEC kind.\n");
+		return -ENOENT;
+	}
+
+	/* Extern-backing datasecs (.ksyms, .kconfig) have their size and
+	 * variable offsets set at the previous step. Further, not every
+	 * extern BTF VAR has corresponding ELF symbol preserved, so we skip
+	 * all fixups altogether for such sections and go straight to sorting
+	 * VARs within their DATASEC.
+	 */
+	if (strcmp(sec_name, KCONFIG_SEC) == 0 || strcmp(sec_name, KSYMS_SEC) == 0)
+		goto sort_vars;
+
+	/* Clang leaves DATASEC size and VAR offsets as zeroes, so we need to
+	 * fix this up. But BPF static linker already fixes this up and fills
+	 * all the sizes and offsets during static linking. So this step has
+	 * to be optional. But the STV_HIDDEN handling is non-optional for any
+	 * non-extern DATASEC, so the variable fixup loop below handles both
+	 * functions at the same time, paying the cost of BTF VAR <-> ELF
+	 * symbol matching just once.
+	 */
+	if (t->size == 0) {
+		err = find_elf_sec_sz(obj, sec_name, &size);
+		if (err || !size) {
+			pr_debug("sec '%s': failed to determine size from ELF: size %u, err %d\n",
+				 sec_name, size, err);
+			return -ENOENT;
+		}
+
+		t->size = size;
+		fixup_offsets = true;
+	}
+
+	for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
+		const struct btf_type *t_var;
+		struct btf_var *var;
+		const char *var_name;
+		Elf64_Sym *sym;
+
+		t_var = btf__type_by_id(btf, vsi->type);
+		if (!t_var || !btf_is_var(t_var)) {
+			pr_debug("sec '%s': unexpected non-VAR type found\n", sec_name);
+			return -EINVAL;
+		}
+
+		var = btf_var(t_var);
+		if (var->linkage == BTF_VAR_STATIC || var->linkage == BTF_VAR_GLOBAL_EXTERN)
+			continue;
+
+		var_name = btf__name_by_offset(btf, t_var->name_off);
+		if (!var_name) {
+			pr_debug("sec '%s': failed to find name of DATASEC's member #%d\n",
+				 sec_name, i);
+			return -ENOENT;
+		}
+
+		sym = find_elf_var_sym(obj, var_name);
+		if (IS_ERR(sym)) {
+			pr_debug("sec '%s': failed to find ELF symbol for VAR '%s'\n",
+				 sec_name, var_name);
+			return -ENOENT;
+		}
+
+		if (fixup_offsets)
+			vsi->offset = sym->st_value;
+
+		/* if variable is a global/weak symbol, but has restricted
+		 * (STV_HIDDEN or STV_INTERNAL) visibility, mark its BTF VAR
+		 * as static. This follows similar logic for functions (BPF
+		 * subprogs) and influences libbpf's further decisions about
+		 * whether to make global data BPF array maps as
+		 * BPF_F_MMAPABLE.
+		 */
+		if (ELF64_ST_VISIBILITY(sym->st_other) == STV_HIDDEN
+		    || ELF64_ST_VISIBILITY(sym->st_other) == STV_INTERNAL)
+			var->linkage = BTF_VAR_STATIC;
+	}
+
+sort_vars:
+	qsort(btf_var_secinfos(t), vars, sizeof(*vsi), compare_vsi_off);
+	return 0;
+}
+
+static int bpf_object_fixup_btf(struct bpf_object *obj)
+{
+	int i, n, err = 0;
+
+	if (!obj->btf)
+		return 0;
+
+	n = btf__type_cnt(obj->btf);
+	for (i = 1; i < n; i++) {
+		struct btf_type *t = btf_type_by_id(obj->btf, i);
+
+		/* Loader needs to fix up some of the things compiler
+		 * couldn't get its hands on while emitting BTF. This
+		 * is section size and global variable offset. We use
+		 * the info from the ELF itself for this purpose.
+		 */
+		if (btf_is_datasec(t)) {
+			err = btf_fixup_datasec(obj, obj->btf, t);
+			if (err)
+				return err;
+		}
+	}
+
+	return 0;
+}
+
+static bool prog_needs_vmlinux_btf(struct bpf_program *prog)
+{
+	if (prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
+	    prog->type == BPF_PROG_TYPE_LSM)
+		return true;
+
+	/* BPF_PROG_TYPE_TRACING programs which do not attach to other programs
+	 * also need vmlinux BTF
+	 */
+	if (prog->type == BPF_PROG_TYPE_TRACING && !prog->attach_prog_fd)
+		return true;
+
+	return false;
+}
+
+static bool obj_needs_vmlinux_btf(const struct bpf_object *obj)
+{
+	struct bpf_program *prog;
+	int i;
+
+	/* CO-RE relocations need kernel BTF, only when btf_custom_path
+	 * is not specified
+	 */
+	if (obj->btf_ext && obj->btf_ext->core_relo_info.len && !obj->btf_custom_path)
+		return true;
+
+	/* Support for typed ksyms needs kernel BTF */
+	for (i = 0; i < obj->nr_extern; i++) {
+		const struct extern_desc *ext;
+
+		ext = &obj->externs[i];
+		if (ext->type == EXT_KSYM && ext->ksym.type_id)
+			return true;
+	}
+
+	bpf_object__for_each_program(prog, obj) {
+		if (!prog->autoload)
+			continue;
+		if (prog_needs_vmlinux_btf(prog))
+			return true;
+	}
+
+	return false;
+}
+
+static int bpf_object__load_vmlinux_btf(struct bpf_object *obj, bool force)
+{
+	int err;
+
+	/* btf_vmlinux could be loaded earlier */
+	if (obj->btf_vmlinux || obj->gen_loader)
+		return 0;
+
+	if (!force && !obj_needs_vmlinux_btf(obj))
+		return 0;
+
+	obj->btf_vmlinux = btf__load_vmlinux_btf();
+	err = libbpf_get_error(obj->btf_vmlinux);
+	if (err) {
+		pr_warn("Error loading vmlinux BTF: %d\n", err);
+		obj->btf_vmlinux = NULL;
+		return err;
+	}
+	return 0;
+}
+
+static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
+{
+	struct btf *kern_btf = obj->btf;
+	bool btf_mandatory, sanitize;
+	int i, err = 0;
+
+	if (!obj->btf)
+		return 0;
+
+	if (!kernel_supports(obj, FEAT_BTF)) {
+		if (kernel_needs_btf(obj)) {
+			err = -EOPNOTSUPP;
+			goto report;
+		}
+		pr_debug("Kernel doesn't support BTF, skipping uploading it.\n");
+		return 0;
+	}
+
+	/* Even though some subprogs are global/weak, user might prefer more
+	 * permissive BPF verification process that BPF verifier performs for
+	 * static functions, taking into account more context from the caller
+	 * functions. In such case, they need to mark such subprogs with
+	 * __attribute__((visibility("hidden"))) and libbpf will adjust
+	 * corresponding FUNC BTF type to be marked as static and trigger more
+	 * involved BPF verification process.
+	 */
+	for (i = 0; i < obj->nr_programs; i++) {
+		struct bpf_program *prog = &obj->programs[i];
+		struct btf_type *t;
+		const char *name;
+		int j, n;
+
+		if (!prog->mark_btf_static || !prog_is_subprog(obj, prog))
+			continue;
+
+		n = btf__type_cnt(obj->btf);
+		for (j = 1; j < n; j++) {
+			t = btf_type_by_id(obj->btf, j);
+			if (!btf_is_func(t) || btf_func_linkage(t) != BTF_FUNC_GLOBAL)
+				continue;
+
+			name = btf__str_by_offset(obj->btf, t->name_off);
+			if (strcmp(name, prog->name) != 0)
+				continue;
+
+			t->info = btf_type_info(BTF_KIND_FUNC, BTF_FUNC_STATIC, 0);
+			break;
+		}
+	}
+
+	sanitize = btf_needs_sanitization(obj);
+	if (sanitize) {
+		const void *raw_data;
+		__u32 sz;
+
+		/* clone BTF to sanitize a copy and leave the original intact */
+		raw_data = btf__raw_data(obj->btf, &sz);
+		kern_btf = btf__new(raw_data, sz);
+		err = libbpf_get_error(kern_btf);
+		if (err)
+			return err;
+
+		/* enforce 8-byte pointers for BPF-targeted BTFs */
+		btf__set_pointer_size(obj->btf, 8);
+		err = bpf_object__sanitize_btf(obj, kern_btf);
+		if (err)
+			return err;
+	}
+
+	if (obj->gen_loader) {
+		__u32 raw_size = 0;
+		const void *raw_data = btf__raw_data(kern_btf, &raw_size);
+
+		if (!raw_data)
+			return -ENOMEM;
+		bpf_gen__load_btf(obj->gen_loader, raw_data, raw_size);
+		/* Pretend to have valid FD to pass various fd >= 0 checks.
+		 * This fd == 0 will not be used with any syscall and will be reset to -1 eventually.
+		 */
+		btf__set_fd(kern_btf, 0);
+	} else {
+		/* currently BPF_BTF_LOAD only supports log_level 1 */
+		err = btf_load_into_kernel(kern_btf, obj->log_buf, obj->log_size,
+					   obj->log_level ? 1 : 0);
+	}
+	if (sanitize) {
+		if (!err) {
+			/* move fd to libbpf's BTF */
+			btf__set_fd(obj->btf, btf__fd(kern_btf));
+			btf__set_fd(kern_btf, -1);
+		}
+		btf__free(kern_btf);
+	}
+report:
+	if (err) {
+		btf_mandatory = kernel_needs_btf(obj);
+		pr_warn("Error loading .BTF into kernel: %d. %s\n", err,
+			btf_mandatory ? "BTF is mandatory, can't proceed."
+				      : "BTF is optional, ignoring.");
+		if (!btf_mandatory)
+			err = 0;
+	}
+	return err;
+}
+
+static const char *elf_sym_str(const struct bpf_object *obj, size_t off)
+{
+	const char *name;
+
+	name = elf_strptr(obj->efile.elf, obj->efile.strtabidx, off);
+	if (!name) {
+		pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
+			off, obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+
+	return name;
+}
+
+static const char *elf_sec_str(const struct bpf_object *obj, size_t off)
+{
+	const char *name;
+
+	name = elf_strptr(obj->efile.elf, obj->efile.shstrndx, off);
+	if (!name) {
+		pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
+			off, obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+
+	return name;
+}
+
+static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx)
+{
+	Elf_Scn *scn;
+
+	scn = elf_getscn(obj->efile.elf, idx);
+	if (!scn) {
+		pr_warn("elf: failed to get section(%zu) from %s: %s\n",
+			idx, obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+	return scn;
+}
+
+static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name)
+{
+	Elf_Scn *scn = NULL;
+	Elf *elf = obj->efile.elf;
+	const char *sec_name;
+
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		sec_name = elf_sec_name(obj, scn);
+		if (!sec_name)
+			return NULL;
+
+		if (strcmp(sec_name, name) != 0)
+			continue;
+
+		return scn;
+	}
+	return NULL;
+}
+
+static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn)
+{
+	Elf64_Shdr *shdr;
+
+	if (!scn)
+		return NULL;
+
+	shdr = elf64_getshdr(scn);
+	if (!shdr) {
+		pr_warn("elf: failed to get section(%zu) header from %s: %s\n",
+			elf_ndxscn(scn), obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+
+	return shdr;
+}
+
+static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn)
+{
+	const char *name;
+	Elf64_Shdr *sh;
+
+	if (!scn)
+		return NULL;
+
+	sh = elf_sec_hdr(obj, scn);
+	if (!sh)
+		return NULL;
+
+	name = elf_sec_str(obj, sh->sh_name);
+	if (!name) {
+		pr_warn("elf: failed to get section(%zu) name from %s: %s\n",
+			elf_ndxscn(scn), obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+
+	return name;
+}
+
+static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn)
+{
+	Elf_Data *data;
+
+	if (!scn)
+		return NULL;
+
+	data = elf_getdata(scn, 0);
+	if (!data) {
+		pr_warn("elf: failed to get section(%zu) %s data from %s: %s\n",
+			elf_ndxscn(scn), elf_sec_name(obj, scn) ?: "<?>",
+			obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+
+	return data;
+}
+
+static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx)
+{
+	if (idx >= obj->efile.symbols->d_size / sizeof(Elf64_Sym))
+		return NULL;
+
+	return (Elf64_Sym *)obj->efile.symbols->d_buf + idx;
+}
+
+static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx)
+{
+	if (idx >= data->d_size / sizeof(Elf64_Rel))
+		return NULL;
+
+	return (Elf64_Rel *)data->d_buf + idx;
+}
+
+static bool is_sec_name_dwarf(const char *name)
+{
+	/* approximation, but the actual list is too long */
+	return str_has_pfx(name, ".debug_");
+}
+
+static bool ignore_elf_section(Elf64_Shdr *hdr, const char *name)
+{
+	/* no special handling of .strtab */
+	if (hdr->sh_type == SHT_STRTAB)
+		return true;
+
+	/* ignore .llvm_addrsig section as well */
+	if (hdr->sh_type == SHT_LLVM_ADDRSIG)
+		return true;
+
+	/* no subprograms will lead to an empty .text section, ignore it */
+	if (hdr->sh_type == SHT_PROGBITS && hdr->sh_size == 0 &&
+	    strcmp(name, ".text") == 0)
+		return true;
+
+	/* DWARF sections */
+	if (is_sec_name_dwarf(name))
+		return true;
+
+	if (str_has_pfx(name, ".rel")) {
+		name += sizeof(".rel") - 1;
+		/* DWARF section relocations */
+		if (is_sec_name_dwarf(name))
+			return true;
+
+		/* .BTF and .BTF.ext don't need relocations */
+		if (strcmp(name, BTF_ELF_SEC) == 0 ||
+		    strcmp(name, BTF_EXT_ELF_SEC) == 0)
+			return true;
+	}
+
+	return false;
+}
+
+static int cmp_progs(const void *_a, const void *_b)
+{
+	const struct bpf_program *a = _a;
+	const struct bpf_program *b = _b;
+
+	if (a->sec_idx != b->sec_idx)
+		return a->sec_idx < b->sec_idx ? -1 : 1;
+
+	/* sec_insn_off can't be the same within the section */
+	return a->sec_insn_off < b->sec_insn_off ? -1 : 1;
+}
+
+static int bpf_object__elf_collect(struct bpf_object *obj)
+{
+	struct elf_sec_desc *sec_desc;
+	Elf *elf = obj->efile.elf;
+	Elf_Data *btf_ext_data = NULL;
+	Elf_Data *btf_data = NULL;
+	int idx = 0, err = 0;
+	const char *name;
+	Elf_Data *data;
+	Elf_Scn *scn;
+	Elf64_Shdr *sh;
+
+	/* ELF section indices are 0-based, but sec #0 is special "invalid"
+	 * section. Since section count retrieved by elf_getshdrnum() does
+	 * include sec #0, it is already the necessary size of an array to keep
+	 * all the sections.
+	 */
+	if (elf_getshdrnum(obj->efile.elf, &obj->efile.sec_cnt)) {
+		pr_warn("elf: failed to get the number of sections for %s: %s\n",
+			obj->path, elf_errmsg(-1));
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	obj->efile.secs = calloc(obj->efile.sec_cnt, sizeof(*obj->efile.secs));
+	if (!obj->efile.secs)
+		return -ENOMEM;
+
+	/* a bunch of ELF parsing functionality depends on processing symbols,
+	 * so do the first pass and find the symbol table
+	 */
+	scn = NULL;
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		sh = elf_sec_hdr(obj, scn);
+		if (!sh)
+			return -LIBBPF_ERRNO__FORMAT;
+
+		if (sh->sh_type == SHT_SYMTAB) {
+			if (obj->efile.symbols) {
+				pr_warn("elf: multiple symbol tables in %s\n", obj->path);
+				return -LIBBPF_ERRNO__FORMAT;
+			}
+
+			data = elf_sec_data(obj, scn);
+			if (!data)
+				return -LIBBPF_ERRNO__FORMAT;
+
+			idx = elf_ndxscn(scn);
+
+			obj->efile.symbols = data;
+			obj->efile.symbols_shndx = idx;
+			obj->efile.strtabidx = sh->sh_link;
+		}
+	}
+
+	if (!obj->efile.symbols) {
+		pr_warn("elf: couldn't find symbol table in %s, stripped object file?\n",
+			obj->path);
+		return -ENOENT;
+	}
+
+	scn = NULL;
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		idx = elf_ndxscn(scn);
+		sec_desc = &obj->efile.secs[idx];
+
+		sh = elf_sec_hdr(obj, scn);
+		if (!sh)
+			return -LIBBPF_ERRNO__FORMAT;
+
+		name = elf_sec_str(obj, sh->sh_name);
+		if (!name)
+			return -LIBBPF_ERRNO__FORMAT;
+
+		if (ignore_elf_section(sh, name))
+			continue;
+
+		data = elf_sec_data(obj, scn);
+		if (!data)
+			return -LIBBPF_ERRNO__FORMAT;
+
+		pr_debug("elf: section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
+			 idx, name, (unsigned long)data->d_size,
+			 (int)sh->sh_link, (unsigned long)sh->sh_flags,
+			 (int)sh->sh_type);
+
+		if (strcmp(name, "license") == 0) {
+			err = bpf_object__init_license(obj, data->d_buf, data->d_size);
+			if (err)
+				return err;
+		} else if (strcmp(name, "version") == 0) {
+			err = bpf_object__init_kversion(obj, data->d_buf, data->d_size);
+			if (err)
+				return err;
+		} else if (strcmp(name, "maps") == 0) {
+			pr_warn("elf: legacy map definitions in 'maps' section are not supported by libbpf v1.0+\n");
+			return -ENOTSUP;
+		} else if (strcmp(name, MAPS_ELF_SEC) == 0) {
+			obj->efile.btf_maps_shndx = idx;
+		} else if (strcmp(name, BTF_ELF_SEC) == 0) {
+			if (sh->sh_type != SHT_PROGBITS)
+				return -LIBBPF_ERRNO__FORMAT;
+			btf_data = data;
+		} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
+			if (sh->sh_type != SHT_PROGBITS)
+				return -LIBBPF_ERRNO__FORMAT;
+			btf_ext_data = data;
+		} else if (sh->sh_type == SHT_SYMTAB) {
+			/* already processed during the first pass above */
+		} else if (sh->sh_type == SHT_PROGBITS && data->d_size > 0) {
+			if (sh->sh_flags & SHF_EXECINSTR) {
+				if (strcmp(name, ".text") == 0)
+					obj->efile.text_shndx = idx;
+				err = bpf_object__add_programs(obj, data, name, idx);
+				if (err)
+					return err;
+			} else if (strcmp(name, DATA_SEC) == 0 ||
+				   str_has_pfx(name, DATA_SEC ".")) {
+				sec_desc->sec_type = SEC_DATA;
+				sec_desc->shdr = sh;
+				sec_desc->data = data;
+			} else if (strcmp(name, RODATA_SEC) == 0 ||
+				   str_has_pfx(name, RODATA_SEC ".")) {
+				sec_desc->sec_type = SEC_RODATA;
+				sec_desc->shdr = sh;
+				sec_desc->data = data;
+			} else if (strcmp(name, STRUCT_OPS_SEC) == 0) {
+				obj->efile.st_ops_data = data;
+				obj->efile.st_ops_shndx = idx;
+			} else {
+				pr_info("elf: skipping unrecognized data section(%d) %s\n",
+					idx, name);
+			}
+		} else if (sh->sh_type == SHT_REL) {
+			int targ_sec_idx = sh->sh_info; /* points to other section */
+
+			if (sh->sh_entsize != sizeof(Elf64_Rel) ||
+			    targ_sec_idx >= obj->efile.sec_cnt)
+				return -LIBBPF_ERRNO__FORMAT;
+
+			/* Only do relo for section with exec instructions */
+			if (!section_have_execinstr(obj, targ_sec_idx) &&
+			    strcmp(name, ".rel" STRUCT_OPS_SEC) &&
+			    strcmp(name, ".rel" MAPS_ELF_SEC)) {
+				pr_info("elf: skipping relo section(%d) %s for section(%d) %s\n",
+					idx, name, targ_sec_idx,
+					elf_sec_name(obj, elf_sec_by_idx(obj, targ_sec_idx)) ?: "<?>");
+				continue;
+			}
+
+			sec_desc->sec_type = SEC_RELO;
+			sec_desc->shdr = sh;
+			sec_desc->data = data;
+		} else if (sh->sh_type == SHT_NOBITS && (strcmp(name, BSS_SEC) == 0 ||
+							 str_has_pfx(name, BSS_SEC "."))) {
+			sec_desc->sec_type = SEC_BSS;
+			sec_desc->shdr = sh;
+			sec_desc->data = data;
+		} else {
+			pr_info("elf: skipping section(%d) %s (size %zu)\n", idx, name,
+				(size_t)sh->sh_size);
+		}
+	}
+
+	if (!obj->efile.strtabidx || obj->efile.strtabidx > idx) {
+		pr_warn("elf: symbol strings section missing or invalid in %s\n", obj->path);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+
+	/* sort BPF programs by section name and in-section instruction offset
+	 * for faster search
+	 */
+	if (obj->nr_programs)
+		qsort(obj->programs, obj->nr_programs, sizeof(*obj->programs), cmp_progs);
+
+	return bpf_object__init_btf(obj, btf_data, btf_ext_data);
+}
+
+static bool sym_is_extern(const Elf64_Sym *sym)
+{
+	int bind = ELF64_ST_BIND(sym->st_info);
+	/* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */
+	return sym->st_shndx == SHN_UNDEF &&
+	       (bind == STB_GLOBAL || bind == STB_WEAK) &&
+	       ELF64_ST_TYPE(sym->st_info) == STT_NOTYPE;
+}
+
+static bool sym_is_subprog(const Elf64_Sym *sym, int text_shndx)
+{
+	int bind = ELF64_ST_BIND(sym->st_info);
+	int type = ELF64_ST_TYPE(sym->st_info);
+
+	/* in .text section */
+	if (sym->st_shndx != text_shndx)
+		return false;
+
+	/* local function */
+	if (bind == STB_LOCAL && type == STT_SECTION)
+		return true;
+
+	/* global function */
+	return bind == STB_GLOBAL && type == STT_FUNC;
+}
+
+static int find_extern_btf_id(const struct btf *btf, const char *ext_name)
+{
+	const struct btf_type *t;
+	const char *tname;
+	int i, n;
+
+	if (!btf)
+		return -ESRCH;
+
+	n = btf__type_cnt(btf);
+	for (i = 1; i < n; i++) {
+		t = btf__type_by_id(btf, i);
+
+		if (!btf_is_var(t) && !btf_is_func(t))
+			continue;
+
+		tname = btf__name_by_offset(btf, t->name_off);
+		if (strcmp(tname, ext_name))
+			continue;
+
+		if (btf_is_var(t) &&
+		    btf_var(t)->linkage != BTF_VAR_GLOBAL_EXTERN)
+			return -EINVAL;
+
+		if (btf_is_func(t) && btf_func_linkage(t) != BTF_FUNC_EXTERN)
+			return -EINVAL;
+
+		return i;
+	}
+
+	return -ENOENT;
+}
+
+static int find_extern_sec_btf_id(struct btf *btf, int ext_btf_id) {
+	const struct btf_var_secinfo *vs;
+	const struct btf_type *t;
+	int i, j, n;
+
+	if (!btf)
+		return -ESRCH;
+
+	n = btf__type_cnt(btf);
+	for (i = 1; i < n; i++) {
+		t = btf__type_by_id(btf, i);
+
+		if (!btf_is_datasec(t))
+			continue;
+
+		vs = btf_var_secinfos(t);
+		for (j = 0; j < btf_vlen(t); j++, vs++) {
+			if (vs->type == ext_btf_id)
+				return i;
+		}
+	}
+
+	return -ENOENT;
+}
+
+static enum kcfg_type find_kcfg_type(const struct btf *btf, int id,
+				     bool *is_signed)
+{
+	const struct btf_type *t;
+	const char *name;
+
+	t = skip_mods_and_typedefs(btf, id, NULL);
+	name = btf__name_by_offset(btf, t->name_off);
+
+	if (is_signed)
+		*is_signed = false;
+	switch (btf_kind(t)) {
+	case BTF_KIND_INT: {
+		int enc = btf_int_encoding(t);
+
+		if (enc & BTF_INT_BOOL)
+			return t->size == 1 ? KCFG_BOOL : KCFG_UNKNOWN;
+		if (is_signed)
+			*is_signed = enc & BTF_INT_SIGNED;
+		if (t->size == 1)
+			return KCFG_CHAR;
+		if (t->size < 1 || t->size > 8 || (t->size & (t->size - 1)))
+			return KCFG_UNKNOWN;
+		return KCFG_INT;
+	}
+	case BTF_KIND_ENUM:
+		if (t->size != 4)
+			return KCFG_UNKNOWN;
+		if (strcmp(name, "libbpf_tristate"))
+			return KCFG_UNKNOWN;
+		return KCFG_TRISTATE;
+	case BTF_KIND_ENUM64:
+		if (strcmp(name, "libbpf_tristate"))
+			return KCFG_UNKNOWN;
+		return KCFG_TRISTATE;
+	case BTF_KIND_ARRAY:
+		if (btf_array(t)->nelems == 0)
+			return KCFG_UNKNOWN;
+		if (find_kcfg_type(btf, btf_array(t)->type, NULL) != KCFG_CHAR)
+			return KCFG_UNKNOWN;
+		return KCFG_CHAR_ARR;
+	default:
+		return KCFG_UNKNOWN;
+	}
+}
+
+static int cmp_externs(const void *_a, const void *_b)
+{
+	const struct extern_desc *a = _a;
+	const struct extern_desc *b = _b;
+
+	if (a->type != b->type)
+		return a->type < b->type ? -1 : 1;
+
+	if (a->type == EXT_KCFG) {
+		/* descending order by alignment requirements */
+		if (a->kcfg.align != b->kcfg.align)
+			return a->kcfg.align > b->kcfg.align ? -1 : 1;
+		/* ascending order by size, within same alignment class */
+		if (a->kcfg.sz != b->kcfg.sz)
+			return a->kcfg.sz < b->kcfg.sz ? -1 : 1;
+	}
+
+	/* resolve ties by name */
+	return strcmp(a->name, b->name);
+}
+
+static int find_int_btf_id(const struct btf *btf)
+{
+	const struct btf_type *t;
+	int i, n;
+
+	n = btf__type_cnt(btf);
+	for (i = 1; i < n; i++) {
+		t = btf__type_by_id(btf, i);
+
+		if (btf_is_int(t) && btf_int_bits(t) == 32)
+			return i;
+	}
+
+	return 0;
+}
+
+static int add_dummy_ksym_var(struct btf *btf)
+{
+	int i, int_btf_id, sec_btf_id, dummy_var_btf_id;
+	const struct btf_var_secinfo *vs;
+	const struct btf_type *sec;
+
+	if (!btf)
+		return 0;
+
+	sec_btf_id = btf__find_by_name_kind(btf, KSYMS_SEC,
+					    BTF_KIND_DATASEC);
+	if (sec_btf_id < 0)
+		return 0;
+
+	sec = btf__type_by_id(btf, sec_btf_id);
+	vs = btf_var_secinfos(sec);
+	for (i = 0; i < btf_vlen(sec); i++, vs++) {
+		const struct btf_type *vt;
+
+		vt = btf__type_by_id(btf, vs->type);
+		if (btf_is_func(vt))
+			break;
+	}
+
+	/* No func in ksyms sec.  No need to add dummy var. */
+	if (i == btf_vlen(sec))
+		return 0;
+
+	int_btf_id = find_int_btf_id(btf);
+	dummy_var_btf_id = btf__add_var(btf,
+					"dummy_ksym",
+					BTF_VAR_GLOBAL_ALLOCATED,
+					int_btf_id);
+	if (dummy_var_btf_id < 0)
+		pr_warn("cannot create a dummy_ksym var\n");
+
+	return dummy_var_btf_id;
+}
+
+static int bpf_object__collect_externs(struct bpf_object *obj)
+{
+	struct btf_type *sec, *kcfg_sec = NULL, *ksym_sec = NULL;
+	const struct btf_type *t;
+	struct extern_desc *ext;
+	int i, n, off, dummy_var_btf_id;
+	const char *ext_name, *sec_name;
+	Elf_Scn *scn;
+	Elf64_Shdr *sh;
+
+	if (!obj->efile.symbols)
+		return 0;
+
+	scn = elf_sec_by_idx(obj, obj->efile.symbols_shndx);
+	sh = elf_sec_hdr(obj, scn);
+	if (!sh || sh->sh_entsize != sizeof(Elf64_Sym))
+		return -LIBBPF_ERRNO__FORMAT;
+
+	dummy_var_btf_id = add_dummy_ksym_var(obj->btf);
+	if (dummy_var_btf_id < 0)
+		return dummy_var_btf_id;
+
+	n = sh->sh_size / sh->sh_entsize;
+	pr_debug("looking for externs among %d symbols...\n", n);
+
+	for (i = 0; i < n; i++) {
+		Elf64_Sym *sym = elf_sym_by_idx(obj, i);
+
+		if (!sym)
+			return -LIBBPF_ERRNO__FORMAT;
+		if (!sym_is_extern(sym))
+			continue;
+		ext_name = elf_sym_str(obj, sym->st_name);
+		if (!ext_name || !ext_name[0])
+			continue;
+
+		ext = obj->externs;
+		ext = libbpf_reallocarray(ext, obj->nr_extern + 1, sizeof(*ext));
+		if (!ext)
+			return -ENOMEM;
+		obj->externs = ext;
+		ext = &ext[obj->nr_extern];
+		memset(ext, 0, sizeof(*ext));
+		obj->nr_extern++;
+
+		ext->btf_id = find_extern_btf_id(obj->btf, ext_name);
+		if (ext->btf_id <= 0) {
+			pr_warn("failed to find BTF for extern '%s': %d\n",
+				ext_name, ext->btf_id);
+			return ext->btf_id;
+		}
+		t = btf__type_by_id(obj->btf, ext->btf_id);
+		ext->name = btf__name_by_offset(obj->btf, t->name_off);
+		ext->sym_idx = i;
+		ext->is_weak = ELF64_ST_BIND(sym->st_info) == STB_WEAK;
+
+		ext->sec_btf_id = find_extern_sec_btf_id(obj->btf, ext->btf_id);
+		if (ext->sec_btf_id <= 0) {
+			pr_warn("failed to find BTF for extern '%s' [%d] section: %d\n",
+				ext_name, ext->btf_id, ext->sec_btf_id);
+			return ext->sec_btf_id;
+		}
+		sec = (void *)btf__type_by_id(obj->btf, ext->sec_btf_id);
+		sec_name = btf__name_by_offset(obj->btf, sec->name_off);
+
+		if (strcmp(sec_name, KCONFIG_SEC) == 0) {
+			if (btf_is_func(t)) {
+				pr_warn("extern function %s is unsupported under %s section\n",
+					ext->name, KCONFIG_SEC);
+				return -ENOTSUP;
+			}
+			kcfg_sec = sec;
+			ext->type = EXT_KCFG;
+			ext->kcfg.sz = btf__resolve_size(obj->btf, t->type);
+			if (ext->kcfg.sz <= 0) {
+				pr_warn("failed to resolve size of extern (kcfg) '%s': %d\n",
+					ext_name, ext->kcfg.sz);
+				return ext->kcfg.sz;
+			}
+			ext->kcfg.align = btf__align_of(obj->btf, t->type);
+			if (ext->kcfg.align <= 0) {
+				pr_warn("failed to determine alignment of extern (kcfg) '%s': %d\n",
+					ext_name, ext->kcfg.align);
+				return -EINVAL;
+			}
+			ext->kcfg.type = find_kcfg_type(obj->btf, t->type,
+							&ext->kcfg.is_signed);
+			if (ext->kcfg.type == KCFG_UNKNOWN) {
+				pr_warn("extern (kcfg) '%s': type is unsupported\n", ext_name);
+				return -ENOTSUP;
+			}
+		} else if (strcmp(sec_name, KSYMS_SEC) == 0) {
+			ksym_sec = sec;
+			ext->type = EXT_KSYM;
+			skip_mods_and_typedefs(obj->btf, t->type,
+					       &ext->ksym.type_id);
+		} else {
+			pr_warn("unrecognized extern section '%s'\n", sec_name);
+			return -ENOTSUP;
+		}
+	}
+	pr_debug("collected %d externs total\n", obj->nr_extern);
+
+	if (!obj->nr_extern)
+		return 0;
+
+	/* sort externs by type, for kcfg ones also by (align, size, name) */
+	qsort(obj->externs, obj->nr_extern, sizeof(*ext), cmp_externs);
+
+	/* for .ksyms section, we need to turn all externs into allocated
+	 * variables in BTF to pass kernel verification; we do this by
+	 * pretending that each extern is a 8-byte variable
+	 */
+	if (ksym_sec) {
+		/* find existing 4-byte integer type in BTF to use for fake
+		 * extern variables in DATASEC
+		 */
+		int int_btf_id = find_int_btf_id(obj->btf);
+		/* For extern function, a dummy_var added earlier
+		 * will be used to replace the vs->type and
+		 * its name string will be used to refill
+		 * the missing param's name.
+		 */
+		const struct btf_type *dummy_var;
+
+		dummy_var = btf__type_by_id(obj->btf, dummy_var_btf_id);
+		for (i = 0; i < obj->nr_extern; i++) {
+			ext = &obj->externs[i];
+			if (ext->type != EXT_KSYM)
+				continue;
+			pr_debug("extern (ksym) #%d: symbol %d, name %s\n",
+				 i, ext->sym_idx, ext->name);
+		}
+
+		sec = ksym_sec;
+		n = btf_vlen(sec);
+		for (i = 0, off = 0; i < n; i++, off += sizeof(int)) {
+			struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
+			struct btf_type *vt;
+
+			vt = (void *)btf__type_by_id(obj->btf, vs->type);
+			ext_name = btf__name_by_offset(obj->btf, vt->name_off);
+			ext = find_extern_by_name(obj, ext_name);
+			if (!ext) {
+				pr_warn("failed to find extern definition for BTF %s '%s'\n",
+					btf_kind_str(vt), ext_name);
+				return -ESRCH;
+			}
+			if (btf_is_func(vt)) {
+				const struct btf_type *func_proto;
+				struct btf_param *param;
+				int j;
+
+				func_proto = btf__type_by_id(obj->btf,
+							     vt->type);
+				param = btf_params(func_proto);
+				/* Reuse the dummy_var string if the
+				 * func proto does not have param name.
+				 */
+				for (j = 0; j < btf_vlen(func_proto); j++)
+					if (param[j].type && !param[j].name_off)
+						param[j].name_off =
+							dummy_var->name_off;
+				vs->type = dummy_var_btf_id;
+				vt->info &= ~0xffff;
+				vt->info |= BTF_FUNC_GLOBAL;
+			} else {
+				btf_var(vt)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
+				vt->type = int_btf_id;
+			}
+			vs->offset = off;
+			vs->size = sizeof(int);
+		}
+		sec->size = off;
+	}
+
+	if (kcfg_sec) {
+		sec = kcfg_sec;
+		/* for kcfg externs calculate their offsets within a .kconfig map */
+		off = 0;
+		for (i = 0; i < obj->nr_extern; i++) {
+			ext = &obj->externs[i];
+			if (ext->type != EXT_KCFG)
+				continue;
+
+			ext->kcfg.data_off = roundup(off, ext->kcfg.align);
+			off = ext->kcfg.data_off + ext->kcfg.sz;
+			pr_debug("extern (kcfg) #%d: symbol %d, off %u, name %s\n",
+				 i, ext->sym_idx, ext->kcfg.data_off, ext->name);
+		}
+		sec->size = off;
+		n = btf_vlen(sec);
+		for (i = 0; i < n; i++) {
+			struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
+
+			t = btf__type_by_id(obj->btf, vs->type);
+			ext_name = btf__name_by_offset(obj->btf, t->name_off);
+			ext = find_extern_by_name(obj, ext_name);
+			if (!ext) {
+				pr_warn("failed to find extern definition for BTF var '%s'\n",
+					ext_name);
+				return -ESRCH;
+			}
+			btf_var(t)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
+			vs->offset = ext->kcfg.data_off;
+		}
+	}
+	return 0;
+}
+
+static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog)
+{
+	return prog->sec_idx == obj->efile.text_shndx && obj->nr_programs > 1;
+}
+
+struct bpf_program *
+bpf_object__find_program_by_name(const struct bpf_object *obj,
+				 const char *name)
+{
+	struct bpf_program *prog;
+
+	bpf_object__for_each_program(prog, obj) {
+		if (prog_is_subprog(obj, prog))
+			continue;
+		if (!strcmp(prog->name, name))
+			return prog;
+	}
+	return errno = ENOENT, NULL;
+}
+
+static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
+				      int shndx)
+{
+	switch (obj->efile.secs[shndx].sec_type) {
+	case SEC_BSS:
+	case SEC_DATA:
+	case SEC_RODATA:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
+				      int shndx)
+{
+	return shndx == obj->efile.btf_maps_shndx;
+}
+
+static enum libbpf_map_type
+bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
+{
+	if (shndx == obj->efile.symbols_shndx)
+		return LIBBPF_MAP_KCONFIG;
+
+	switch (obj->efile.secs[shndx].sec_type) {
+	case SEC_BSS:
+		return LIBBPF_MAP_BSS;
+	case SEC_DATA:
+		return LIBBPF_MAP_DATA;
+	case SEC_RODATA:
+		return LIBBPF_MAP_RODATA;
+	default:
+		return LIBBPF_MAP_UNSPEC;
+	}
+}
+
+static int bpf_program__record_reloc(struct bpf_program *prog,
+				     struct reloc_desc *reloc_desc,
+				     __u32 insn_idx, const char *sym_name,
+				     const Elf64_Sym *sym, const Elf64_Rel *rel)
+{
+	struct bpf_insn *insn = &prog->insns[insn_idx];
+	size_t map_idx, nr_maps = prog->obj->nr_maps;
+	struct bpf_object *obj = prog->obj;
+	__u32 shdr_idx = sym->st_shndx;
+	enum libbpf_map_type type;
+	const char *sym_sec_name;
+	struct bpf_map *map;
+
+	if (!is_call_insn(insn) && !is_ldimm64_insn(insn)) {
+		pr_warn("prog '%s': invalid relo against '%s' for insns[%d].code 0x%x\n",
+			prog->name, sym_name, insn_idx, insn->code);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+
+	if (sym_is_extern(sym)) {
+		int sym_idx = ELF64_R_SYM(rel->r_info);
+		int i, n = obj->nr_extern;
+		struct extern_desc *ext;
+
+		for (i = 0; i < n; i++) {
+			ext = &obj->externs[i];
+			if (ext->sym_idx == sym_idx)
+				break;
+		}
+		if (i >= n) {
+			pr_warn("prog '%s': extern relo failed to find extern for '%s' (%d)\n",
+				prog->name, sym_name, sym_idx);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		pr_debug("prog '%s': found extern #%d '%s' (sym %d) for insn #%u\n",
+			 prog->name, i, ext->name, ext->sym_idx, insn_idx);
+		if (insn->code == (BPF_JMP | BPF_CALL))
+			reloc_desc->type = RELO_EXTERN_FUNC;
+		else
+			reloc_desc->type = RELO_EXTERN_VAR;
+		reloc_desc->insn_idx = insn_idx;
+		reloc_desc->sym_off = i; /* sym_off stores extern index */
+		return 0;
+	}
+
+	/* sub-program call relocation */
+	if (is_call_insn(insn)) {
+		if (insn->src_reg != BPF_PSEUDO_CALL) {
+			pr_warn("prog '%s': incorrect bpf_call opcode\n", prog->name);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		/* text_shndx can be 0, if no default "main" program exists */
+		if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
+			sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
+			pr_warn("prog '%s': bad call relo against '%s' in section '%s'\n",
+				prog->name, sym_name, sym_sec_name);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		if (sym->st_value % BPF_INSN_SZ) {
+			pr_warn("prog '%s': bad call relo against '%s' at offset %zu\n",
+				prog->name, sym_name, (size_t)sym->st_value);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		reloc_desc->type = RELO_CALL;
+		reloc_desc->insn_idx = insn_idx;
+		reloc_desc->sym_off = sym->st_value;
+		return 0;
+	}
+
+	if (!shdr_idx || shdr_idx >= SHN_LORESERVE) {
+		pr_warn("prog '%s': invalid relo against '%s' in special section 0x%x; forgot to initialize global var?..\n",
+			prog->name, sym_name, shdr_idx);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+
+	/* loading subprog addresses */
+	if (sym_is_subprog(sym, obj->efile.text_shndx)) {
+		/* global_func: sym->st_value = offset in the section, insn->imm = 0.
+		 * local_func: sym->st_value = 0, insn->imm = offset in the section.
+		 */
+		if ((sym->st_value % BPF_INSN_SZ) || (insn->imm % BPF_INSN_SZ)) {
+			pr_warn("prog '%s': bad subprog addr relo against '%s' at offset %zu+%d\n",
+				prog->name, sym_name, (size_t)sym->st_value, insn->imm);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+
+		reloc_desc->type = RELO_SUBPROG_ADDR;
+		reloc_desc->insn_idx = insn_idx;
+		reloc_desc->sym_off = sym->st_value;
+		return 0;
+	}
+
+	type = bpf_object__section_to_libbpf_map_type(obj, shdr_idx);
+	sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
+
+	/* generic map reference relocation */
+	if (type == LIBBPF_MAP_UNSPEC) {
+		if (!bpf_object__shndx_is_maps(obj, shdr_idx)) {
+			pr_warn("prog '%s': bad map relo against '%s' in section '%s'\n",
+				prog->name, sym_name, sym_sec_name);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		for (map_idx = 0; map_idx < nr_maps; map_idx++) {
+			map = &obj->maps[map_idx];
+			if (map->libbpf_type != type ||
+			    map->sec_idx != sym->st_shndx ||
+			    map->sec_offset != sym->st_value)
+				continue;
+			pr_debug("prog '%s': found map %zd (%s, sec %d, off %zu) for insn #%u\n",
+				 prog->name, map_idx, map->name, map->sec_idx,
+				 map->sec_offset, insn_idx);
+			break;
+		}
+		if (map_idx >= nr_maps) {
+			pr_warn("prog '%s': map relo failed to find map for section '%s', off %zu\n",
+				prog->name, sym_sec_name, (size_t)sym->st_value);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		reloc_desc->type = RELO_LD64;
+		reloc_desc->insn_idx = insn_idx;
+		reloc_desc->map_idx = map_idx;
+		reloc_desc->sym_off = 0; /* sym->st_value determines map_idx */
+		return 0;
+	}
+
+	/* global data map relocation */
+	if (!bpf_object__shndx_is_data(obj, shdr_idx)) {
+		pr_warn("prog '%s': bad data relo against section '%s'\n",
+			prog->name, sym_sec_name);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+	for (map_idx = 0; map_idx < nr_maps; map_idx++) {
+		map = &obj->maps[map_idx];
+		if (map->libbpf_type != type || map->sec_idx != sym->st_shndx)
+			continue;
+		pr_debug("prog '%s': found data map %zd (%s, sec %d, off %zu) for insn %u\n",
+			 prog->name, map_idx, map->name, map->sec_idx,
+			 map->sec_offset, insn_idx);
+		break;
+	}
+	if (map_idx >= nr_maps) {
+		pr_warn("prog '%s': data relo failed to find map for section '%s'\n",
+			prog->name, sym_sec_name);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+
+	reloc_desc->type = RELO_DATA;
+	reloc_desc->insn_idx = insn_idx;
+	reloc_desc->map_idx = map_idx;
+	reloc_desc->sym_off = sym->st_value;
+	return 0;
+}
+
+static bool prog_contains_insn(const struct bpf_program *prog, size_t insn_idx)
+{
+	return insn_idx >= prog->sec_insn_off &&
+	       insn_idx < prog->sec_insn_off + prog->sec_insn_cnt;
+}
+
+static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj,
+						 size_t sec_idx, size_t insn_idx)
+{
+	int l = 0, r = obj->nr_programs - 1, m;
+	struct bpf_program *prog;
+
+	if (!obj->nr_programs)
+		return NULL;
+
+	while (l < r) {
+		m = l + (r - l + 1) / 2;
+		prog = &obj->programs[m];
+
+		if (prog->sec_idx < sec_idx ||
+		    (prog->sec_idx == sec_idx && prog->sec_insn_off <= insn_idx))
+			l = m;
+		else
+			r = m - 1;
+	}
+	/* matching program could be at index l, but it still might be the
+	 * wrong one, so we need to double check conditions for the last time
+	 */
+	prog = &obj->programs[l];
+	if (prog->sec_idx == sec_idx && prog_contains_insn(prog, insn_idx))
+		return prog;
+	return NULL;
+}
+
+static int
+bpf_object__collect_prog_relos(struct bpf_object *obj, Elf64_Shdr *shdr, Elf_Data *data)
+{
+	const char *relo_sec_name, *sec_name;
+	size_t sec_idx = shdr->sh_info, sym_idx;
+	struct bpf_program *prog;
+	struct reloc_desc *relos;
+	int err, i, nrels;
+	const char *sym_name;
+	__u32 insn_idx;
+	Elf_Scn *scn;
+	Elf_Data *scn_data;
+	Elf64_Sym *sym;
+	Elf64_Rel *rel;
+
+	if (sec_idx >= obj->efile.sec_cnt)
+		return -EINVAL;
+
+	scn = elf_sec_by_idx(obj, sec_idx);
+	scn_data = elf_sec_data(obj, scn);
+
+	relo_sec_name = elf_sec_str(obj, shdr->sh_name);
+	sec_name = elf_sec_name(obj, scn);
+	if (!relo_sec_name || !sec_name)
+		return -EINVAL;
+
+	pr_debug("sec '%s': collecting relocation for section(%zu) '%s'\n",
+		 relo_sec_name, sec_idx, sec_name);
+	nrels = shdr->sh_size / shdr->sh_entsize;
+
+	for (i = 0; i < nrels; i++) {
+		rel = elf_rel_by_idx(data, i);
+		if (!rel) {
+			pr_warn("sec '%s': failed to get relo #%d\n", relo_sec_name, i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		sym_idx = ELF64_R_SYM(rel->r_info);
+		sym = elf_sym_by_idx(obj, sym_idx);
+		if (!sym) {
+			pr_warn("sec '%s': symbol #%zu not found for relo #%d\n",
+				relo_sec_name, sym_idx, i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		if (sym->st_shndx >= obj->efile.sec_cnt) {
+			pr_warn("sec '%s': corrupted symbol #%zu pointing to invalid section #%zu for relo #%d\n",
+				relo_sec_name, sym_idx, (size_t)sym->st_shndx, i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		if (rel->r_offset % BPF_INSN_SZ || rel->r_offset >= scn_data->d_size) {
+			pr_warn("sec '%s': invalid offset 0x%zx for relo #%d\n",
+				relo_sec_name, (size_t)rel->r_offset, i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		insn_idx = rel->r_offset / BPF_INSN_SZ;
+		/* relocations against static functions are recorded as
+		 * relocations against the section that contains a function;
+		 * in such case, symbol will be STT_SECTION and sym.st_name
+		 * will point to empty string (0), so fetch section name
+		 * instead
+		 */
+		if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION && sym->st_name == 0)
+			sym_name = elf_sec_name(obj, elf_sec_by_idx(obj, sym->st_shndx));
+		else
+			sym_name = elf_sym_str(obj, sym->st_name);
+		sym_name = sym_name ?: "<?";
+
+		pr_debug("sec '%s': relo #%d: insn #%u against '%s'\n",
+			 relo_sec_name, i, insn_idx, sym_name);
+
+		prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
+		if (!prog) {
+			pr_debug("sec '%s': relo #%d: couldn't find program in section '%s' for insn #%u, probably overridden weak function, skipping...\n",
+				relo_sec_name, i, sec_name, insn_idx);
+			continue;
+		}
+
+		relos = libbpf_reallocarray(prog->reloc_desc,
+					    prog->nr_reloc + 1, sizeof(*relos));
+		if (!relos)
+			return -ENOMEM;
+		prog->reloc_desc = relos;
+
+		/* adjust insn_idx to local BPF program frame of reference */
+		insn_idx -= prog->sec_insn_off;
+		err = bpf_program__record_reloc(prog, &relos[prog->nr_reloc],
+						insn_idx, sym_name, sym, rel);
+		if (err)
+			return err;
+
+		prog->nr_reloc++;
+	}
+	return 0;
+}
+
+static int map_fill_btf_type_info(struct bpf_object *obj, struct bpf_map *map)
+{
+	int id;
+
+	if (!obj->btf)
+		return -ENOENT;
+
+	/* if it's BTF-defined map, we don't need to search for type IDs.
+	 * For struct_ops map, it does not need btf_key_type_id and
+	 * btf_value_type_id.
+	 */
+	if (map->sec_idx == obj->efile.btf_maps_shndx || bpf_map__is_struct_ops(map))
+		return 0;
+
+	/*
+	 * LLVM annotates global data differently in BTF, that is,
+	 * only as '.data', '.bss' or '.rodata'.
+	 */
+	if (!bpf_map__is_internal(map))
+		return -ENOENT;
+
+	id = btf__find_by_name(obj->btf, map->real_name);
+	if (id < 0)
+		return id;
+
+	map->btf_key_type_id = 0;
+	map->btf_value_type_id = id;
+	return 0;
+}
+
+static int bpf_get_map_info_from_fdinfo(int fd, struct bpf_map_info *info)
+{
+	char file[PATH_MAX], buff[4096];
+	FILE *fp;
+	__u32 val;
+	int err;
+
+	snprintf(file, sizeof(file), "/proc/%d/fdinfo/%d", getpid(), fd);
+	memset(info, 0, sizeof(*info));
+
+	fp = fopen(file, "r");
+	if (!fp) {
+		err = -errno;
+		pr_warn("failed to open %s: %d. No procfs support?\n", file,
+			err);
+		return err;
+	}
+
+	while (fgets(buff, sizeof(buff), fp)) {
+		if (sscanf(buff, "map_type:\t%u", &val) == 1)
+			info->type = val;
+		else if (sscanf(buff, "key_size:\t%u", &val) == 1)
+			info->key_size = val;
+		else if (sscanf(buff, "value_size:\t%u", &val) == 1)
+			info->value_size = val;
+		else if (sscanf(buff, "max_entries:\t%u", &val) == 1)
+			info->max_entries = val;
+		else if (sscanf(buff, "map_flags:\t%i", &val) == 1)
+			info->map_flags = val;
+	}
+
+	fclose(fp);
+
+	return 0;
+}
+
+bool bpf_map__autocreate(const struct bpf_map *map)
+{
+	return map->autocreate;
+}
+
+int bpf_map__set_autocreate(struct bpf_map *map, bool autocreate)
+{
+	if (map->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	map->autocreate = autocreate;
+	return 0;
+}
+
+int bpf_map__reuse_fd(struct bpf_map *map, int fd)
+{
+	struct bpf_map_info info;
+	__u32 len = sizeof(info), name_len;
+	int new_fd, err;
+	char *new_name;
+
+	memset(&info, 0, len);
+	err = bpf_obj_get_info_by_fd(fd, &info, &len);
+	if (err && errno == EINVAL)
+		err = bpf_get_map_info_from_fdinfo(fd, &info);
+	if (err)
+		return libbpf_err(err);
+
+	name_len = strlen(info.name);
+	if (name_len == BPF_OBJ_NAME_LEN - 1 && strncmp(map->name, info.name, name_len) == 0)
+		new_name = strdup(map->name);
+	else
+		new_name = strdup(info.name);
+
+	if (!new_name)
+		return libbpf_err(-errno);
+
+	new_fd = open("/", O_RDONLY | O_CLOEXEC);
+	if (new_fd < 0) {
+		err = -errno;
+		goto err_free_new_name;
+	}
+
+	new_fd = dup3(fd, new_fd, O_CLOEXEC);
+	if (new_fd < 0) {
+		err = -errno;
+		goto err_close_new_fd;
+	}
+
+	err = zclose(map->fd);
+	if (err) {
+		err = -errno;
+		goto err_close_new_fd;
+	}
+	free(map->name);
+
+	map->fd = new_fd;
+	map->name = new_name;
+	map->def.type = info.type;
+	map->def.key_size = info.key_size;
+	map->def.value_size = info.value_size;
+	map->def.max_entries = info.max_entries;
+	map->def.map_flags = info.map_flags;
+	map->btf_key_type_id = info.btf_key_type_id;
+	map->btf_value_type_id = info.btf_value_type_id;
+	map->reused = true;
+	map->map_extra = info.map_extra;
+
+	return 0;
+
+err_close_new_fd:
+	close(new_fd);
+err_free_new_name:
+	free(new_name);
+	return libbpf_err(err);
+}
+
+__u32 bpf_map__max_entries(const struct bpf_map *map)
+{
+	return map->def.max_entries;
+}
+
+struct bpf_map *bpf_map__inner_map(struct bpf_map *map)
+{
+	if (!bpf_map_type__is_map_in_map(map->def.type))
+		return errno = EINVAL, NULL;
+
+	return map->inner_map;
+}
+
+int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries)
+{
+	if (map->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	map->def.max_entries = max_entries;
+
+	/* auto-adjust BPF ringbuf map max_entries to be a multiple of page size */
+	if (map_is_ringbuf(map))
+		map->def.max_entries = adjust_ringbuf_sz(map->def.max_entries);
+
+	return 0;
+}
+
+static int
+bpf_object__probe_loading(struct bpf_object *obj)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int ret, insn_cnt = ARRAY_SIZE(insns);
+
+	if (obj->gen_loader)
+		return 0;
+
+	ret = bump_rlimit_memlock();
+	if (ret)
+		pr_warn("Failed to bump RLIMIT_MEMLOCK (err = %d), you might need to do it explicitly!\n", ret);
+
+	/* make sure basic loading works */
+	ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
+	if (ret < 0)
+		ret = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, NULL);
+	if (ret < 0) {
+		ret = errno;
+		cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
+		pr_warn("Error in %s():%s(%d). Couldn't load trivial BPF "
+			"program. Make sure your kernel supports BPF "
+			"(CONFIG_BPF_SYSCALL=y) and/or that RLIMIT_MEMLOCK is "
+			"set to big enough value.\n", __func__, cp, ret);
+		return -ret;
+	}
+	close(ret);
+
+	return 0;
+}
+
+static int probe_fd(int fd)
+{
+	if (fd >= 0)
+		close(fd);
+	return fd >= 0;
+}
+
+static int probe_kern_prog_name(void)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, prog_name);
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	attr.license = ptr_to_u64("GPL");
+	attr.insns = ptr_to_u64(insns);
+	attr.insn_cnt = (__u32)ARRAY_SIZE(insns);
+	libbpf_strlcpy(attr.prog_name, "libbpf_nametest", sizeof(attr.prog_name));
+
+	/* make sure loading with name works */
+	ret = sys_bpf_prog_load(&attr, attr_sz, PROG_LOAD_ATTEMPTS);
+	return probe_fd(ret);
+}
+
+static int probe_kern_global_data(void)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct bpf_insn insns[] = {
+		BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16),
+		BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42),
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int ret, map, insn_cnt = ARRAY_SIZE(insns);
+
+	map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_global", sizeof(int), 32, 1, NULL);
+	if (map < 0) {
+		ret = -errno;
+		cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
+		pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
+			__func__, cp, -ret);
+		return ret;
+	}
+
+	insns[0].imm = map;
+
+	ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
+	close(map);
+	return probe_fd(ret);
+}
+
+static int probe_kern_btf(void)
+{
+	static const char strs[] = "\0int";
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_func(void)
+{
+	static const char strs[] = "\0int\0x\0a";
+	/* void x(int a) {} */
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* FUNC_PROTO */                                /* [2] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
+		BTF_PARAM_ENC(7, 1),
+		/* FUNC x */                                    /* [3] */
+		BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_func_global(void)
+{
+	static const char strs[] = "\0int\0x\0a";
+	/* static void x(int a) {} */
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* FUNC_PROTO */                                /* [2] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
+		BTF_PARAM_ENC(7, 1),
+		/* FUNC x BTF_FUNC_GLOBAL */                    /* [3] */
+		BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_datasec(void)
+{
+	static const char strs[] = "\0x\0.data";
+	/* static int a; */
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* VAR x */                                     /* [2] */
+		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
+		BTF_VAR_STATIC,
+		/* DATASEC val */                               /* [3] */
+		BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
+		BTF_VAR_SECINFO_ENC(2, 0, 4),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_float(void)
+{
+	static const char strs[] = "\0float";
+	__u32 types[] = {
+		/* float */
+		BTF_TYPE_FLOAT_ENC(1, 4),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_decl_tag(void)
+{
+	static const char strs[] = "\0tag";
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* VAR x */                                     /* [2] */
+		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
+		BTF_VAR_STATIC,
+		/* attr */
+		BTF_TYPE_DECL_TAG_ENC(1, 2, -1),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_type_tag(void)
+{
+	static const char strs[] = "\0tag";
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),		/* [1] */
+		/* attr */
+		BTF_TYPE_TYPE_TAG_ENC(1, 1),				/* [2] */
+		/* ptr */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 2),	/* [3] */
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_array_mmap(void)
+{
+	LIBBPF_OPTS(bpf_map_create_opts, opts, .map_flags = BPF_F_MMAPABLE);
+	int fd;
+
+	fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_mmap", sizeof(int), sizeof(int), 1, &opts);
+	return probe_fd(fd);
+}
+
+static int probe_kern_exp_attach_type(void)
+{
+	LIBBPF_OPTS(bpf_prog_load_opts, opts, .expected_attach_type = BPF_CGROUP_INET_SOCK_CREATE);
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int fd, insn_cnt = ARRAY_SIZE(insns);
+
+	/* use any valid combination of program type and (optional)
+	 * non-zero expected attach type (i.e., not a BPF_CGROUP_INET_INGRESS)
+	 * to see if kernel supports expected_attach_type field for
+	 * BPF_PROG_LOAD command
+	 */
+	fd = bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCK, NULL, "GPL", insns, insn_cnt, &opts);
+	return probe_fd(fd);
+}
+
+static int probe_kern_probe_read_kernel(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),	/* r1 = r10 (fp) */
+		BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8),	/* r1 += -8 */
+		BPF_MOV64_IMM(BPF_REG_2, 8),		/* r2 = 8 */
+		BPF_MOV64_IMM(BPF_REG_3, 0),		/* r3 = 0 */
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_probe_read_kernel),
+		BPF_EXIT_INSN(),
+	};
+	int fd, insn_cnt = ARRAY_SIZE(insns);
+
+	fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, NULL);
+	return probe_fd(fd);
+}
+
+static int probe_prog_bind_map(void)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int ret, map, prog, insn_cnt = ARRAY_SIZE(insns);
+
+	map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_det_bind", sizeof(int), 32, 1, NULL);
+	if (map < 0) {
+		ret = -errno;
+		cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
+		pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
+			__func__, cp, -ret);
+		return ret;
+	}
+
+	prog = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
+	if (prog < 0) {
+		close(map);
+		return 0;
+	}
+
+	ret = bpf_prog_bind_map(prog, map, NULL);
+
+	close(map);
+	close(prog);
+
+	return ret >= 0;
+}
+
+static int probe_module_btf(void)
+{
+	static const char strs[] = "\0int";
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
+	};
+	struct bpf_btf_info info;
+	__u32 len = sizeof(info);
+	char name[16];
+	int fd, err;
+
+	fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs));
+	if (fd < 0)
+		return 0; /* BTF not supported at all */
+
+	memset(&info, 0, sizeof(info));
+	info.name = ptr_to_u64(name);
+	info.name_len = sizeof(name);
+
+	/* check that BPF_OBJ_GET_INFO_BY_FD supports specifying name pointer;
+	 * kernel's module BTF support coincides with support for
+	 * name/name_len fields in struct bpf_btf_info.
+	 */
+	err = bpf_obj_get_info_by_fd(fd, &info, &len);
+	close(fd);
+	return !err;
+}
+
+static int probe_perf_link(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int prog_fd, link_fd, err;
+
+	prog_fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL",
+				insns, ARRAY_SIZE(insns), NULL);
+	if (prog_fd < 0)
+		return -errno;
+
+	/* use invalid perf_event FD to get EBADF, if link is supported;
+	 * otherwise EINVAL should be returned
+	 */
+	link_fd = bpf_link_create(prog_fd, -1, BPF_PERF_EVENT, NULL);
+	err = -errno; /* close() can clobber errno */
+
+	if (link_fd >= 0)
+		close(link_fd);
+	close(prog_fd);
+
+	return link_fd < 0 && err == -EBADF;
+}
+
+static int probe_kern_bpf_cookie(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_attach_cookie),
+		BPF_EXIT_INSN(),
+	};
+	int ret, insn_cnt = ARRAY_SIZE(insns);
+
+	ret = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", insns, insn_cnt, NULL);
+	return probe_fd(ret);
+}
+
+static int probe_kern_btf_enum64(void)
+{
+	static const char strs[] = "\0enum64";
+	__u32 types[] = {
+		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_ENUM64, 0, 0), 8),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_syscall_wrapper(void);
+
+enum kern_feature_result {
+	FEAT_UNKNOWN = 0,
+	FEAT_SUPPORTED = 1,
+	FEAT_MISSING = 2,
+};
+
+typedef int (*feature_probe_fn)(void);
+
+static struct kern_feature_desc {
+	const char *desc;
+	feature_probe_fn probe;
+	enum kern_feature_result res;
+} feature_probes[__FEAT_CNT] = {
+	[FEAT_PROG_NAME] = {
+		"BPF program name", probe_kern_prog_name,
+	},
+	[FEAT_GLOBAL_DATA] = {
+		"global variables", probe_kern_global_data,
+	},
+	[FEAT_BTF] = {
+		"minimal BTF", probe_kern_btf,
+	},
+	[FEAT_BTF_FUNC] = {
+		"BTF functions", probe_kern_btf_func,
+	},
+	[FEAT_BTF_GLOBAL_FUNC] = {
+		"BTF global function", probe_kern_btf_func_global,
+	},
+	[FEAT_BTF_DATASEC] = {
+		"BTF data section and variable", probe_kern_btf_datasec,
+	},
+	[FEAT_ARRAY_MMAP] = {
+		"ARRAY map mmap()", probe_kern_array_mmap,
+	},
+	[FEAT_EXP_ATTACH_TYPE] = {
+		"BPF_PROG_LOAD expected_attach_type attribute",
+		probe_kern_exp_attach_type,
+	},
+	[FEAT_PROBE_READ_KERN] = {
+		"bpf_probe_read_kernel() helper", probe_kern_probe_read_kernel,
+	},
+	[FEAT_PROG_BIND_MAP] = {
+		"BPF_PROG_BIND_MAP support", probe_prog_bind_map,
+	},
+	[FEAT_MODULE_BTF] = {
+		"module BTF support", probe_module_btf,
+	},
+	[FEAT_BTF_FLOAT] = {
+		"BTF_KIND_FLOAT support", probe_kern_btf_float,
+	},
+	[FEAT_PERF_LINK] = {
+		"BPF perf link support", probe_perf_link,
+	},
+	[FEAT_BTF_DECL_TAG] = {
+		"BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag,
+	},
+	[FEAT_BTF_TYPE_TAG] = {
+		"BTF_KIND_TYPE_TAG support", probe_kern_btf_type_tag,
+	},
+	[FEAT_MEMCG_ACCOUNT] = {
+		"memcg-based memory accounting", probe_memcg_account,
+	},
+	[FEAT_BPF_COOKIE] = {
+		"BPF cookie support", probe_kern_bpf_cookie,
+	},
+	[FEAT_BTF_ENUM64] = {
+		"BTF_KIND_ENUM64 support", probe_kern_btf_enum64,
+	},
+	[FEAT_SYSCALL_WRAPPER] = {
+		"Kernel using syscall wrapper", probe_kern_syscall_wrapper,
+	},
+};
+
+bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)
+{
+	struct kern_feature_desc *feat = &feature_probes[feat_id];
+	int ret;
+
+	if (obj && obj->gen_loader)
+		/* To generate loader program assume the latest kernel
+		 * to avoid doing extra prog_load, map_create syscalls.
+		 */
+		return true;
+
+	if (READ_ONCE(feat->res) == FEAT_UNKNOWN) {
+		ret = feat->probe();
+		if (ret > 0) {
+			WRITE_ONCE(feat->res, FEAT_SUPPORTED);
+		} else if (ret == 0) {
+			WRITE_ONCE(feat->res, FEAT_MISSING);
+		} else {
+			pr_warn("Detection of kernel %s support failed: %d\n", feat->desc, ret);
+			WRITE_ONCE(feat->res, FEAT_MISSING);
+		}
+	}
+
+	return READ_ONCE(feat->res) == FEAT_SUPPORTED;
+}
+
+static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
+{
+	struct bpf_map_info map_info;
+	char msg[STRERR_BUFSIZE];
+	__u32 map_info_len = sizeof(map_info);
+	int err;
+
+	memset(&map_info, 0, map_info_len);
+	err = bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len);
+	if (err && errno == EINVAL)
+		err = bpf_get_map_info_from_fdinfo(map_fd, &map_info);
+	if (err) {
+		pr_warn("failed to get map info for map FD %d: %s\n", map_fd,
+			libbpf_strerror_r(errno, msg, sizeof(msg)));
+		return false;
+	}
+
+	return (map_info.type == map->def.type &&
+		map_info.key_size == map->def.key_size &&
+		map_info.value_size == map->def.value_size &&
+		map_info.max_entries == map->def.max_entries &&
+		map_info.map_flags == map->def.map_flags &&
+		map_info.map_extra == map->map_extra);
+}
+
+static int
+bpf_object__reuse_map(struct bpf_map *map)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err, pin_fd;
+
+	pin_fd = bpf_obj_get(map->pin_path);
+	if (pin_fd < 0) {
+		err = -errno;
+		if (err == -ENOENT) {
+			pr_debug("found no pinned map to reuse at '%s'\n",
+				 map->pin_path);
+			return 0;
+		}
+
+		cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
+		pr_warn("couldn't retrieve pinned map '%s': %s\n",
+			map->pin_path, cp);
+		return err;
+	}
+
+	if (!map_is_reuse_compat(map, pin_fd)) {
+		pr_warn("couldn't reuse pinned map at '%s': parameter mismatch\n",
+			map->pin_path);
+		close(pin_fd);
+		return -EINVAL;
+	}
+
+	err = bpf_map__reuse_fd(map, pin_fd);
+	close(pin_fd);
+	if (err)
+		return err;
+
+	map->pinned = true;
+	pr_debug("reused pinned map at '%s'\n", map->pin_path);
+
+	return 0;
+}
+
+static int
+bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
+{
+	enum libbpf_map_type map_type = map->libbpf_type;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err, zero = 0;
+
+	if (obj->gen_loader) {
+		bpf_gen__map_update_elem(obj->gen_loader, map - obj->maps,
+					 map->mmaped, map->def.value_size);
+		if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG)
+			bpf_gen__map_freeze(obj->gen_loader, map - obj->maps);
+		return 0;
+	}
+	err = bpf_map_update_elem(map->fd, &zero, map->mmaped, 0);
+	if (err) {
+		err = -errno;
+		cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+		pr_warn("Error setting initial map(%s) contents: %s\n",
+			map->name, cp);
+		return err;
+	}
+
+	/* Freeze .rodata and .kconfig map as read-only from syscall side. */
+	if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG) {
+		err = bpf_map_freeze(map->fd);
+		if (err) {
+			err = -errno;
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+			pr_warn("Error freezing map(%s) as read-only: %s\n",
+				map->name, cp);
+			return err;
+		}
+	}
+	return 0;
+}
+
+static void bpf_map__destroy(struct bpf_map *map);
+
+static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, bool is_inner)
+{
+	LIBBPF_OPTS(bpf_map_create_opts, create_attr);
+	struct bpf_map_def *def = &map->def;
+	const char *map_name = NULL;
+	int err = 0;
+
+	if (kernel_supports(obj, FEAT_PROG_NAME))
+		map_name = map->name;
+	create_attr.map_ifindex = map->map_ifindex;
+	create_attr.map_flags = def->map_flags;
+	create_attr.numa_node = map->numa_node;
+	create_attr.map_extra = map->map_extra;
+
+	if (bpf_map__is_struct_ops(map))
+		create_attr.btf_vmlinux_value_type_id = map->btf_vmlinux_value_type_id;
+
+	if (obj->btf && btf__fd(obj->btf) >= 0) {
+		create_attr.btf_fd = btf__fd(obj->btf);
+		create_attr.btf_key_type_id = map->btf_key_type_id;
+		create_attr.btf_value_type_id = map->btf_value_type_id;
+	}
+
+	if (bpf_map_type__is_map_in_map(def->type)) {
+		if (map->inner_map) {
+			err = bpf_object__create_map(obj, map->inner_map, true);
+			if (err) {
+				pr_warn("map '%s': failed to create inner map: %d\n",
+					map->name, err);
+				return err;
+			}
+			map->inner_map_fd = bpf_map__fd(map->inner_map);
+		}
+		if (map->inner_map_fd >= 0)
+			create_attr.inner_map_fd = map->inner_map_fd;
+	}
+
+	switch (def->type) {
+	case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
+	case BPF_MAP_TYPE_CGROUP_ARRAY:
+	case BPF_MAP_TYPE_STACK_TRACE:
+	case BPF_MAP_TYPE_ARRAY_OF_MAPS:
+	case BPF_MAP_TYPE_HASH_OF_MAPS:
+	case BPF_MAP_TYPE_DEVMAP:
+	case BPF_MAP_TYPE_DEVMAP_HASH:
+	case BPF_MAP_TYPE_CPUMAP:
+	case BPF_MAP_TYPE_XSKMAP:
+	case BPF_MAP_TYPE_SOCKMAP:
+	case BPF_MAP_TYPE_SOCKHASH:
+	case BPF_MAP_TYPE_QUEUE:
+	case BPF_MAP_TYPE_STACK:
+		create_attr.btf_fd = 0;
+		create_attr.btf_key_type_id = 0;
+		create_attr.btf_value_type_id = 0;
+		map->btf_key_type_id = 0;
+		map->btf_value_type_id = 0;
+	default:
+		break;
+	}
+
+	if (obj->gen_loader) {
+		bpf_gen__map_create(obj->gen_loader, def->type, map_name,
+				    def->key_size, def->value_size, def->max_entries,
+				    &create_attr, is_inner ? -1 : map - obj->maps);
+		/* Pretend to have valid FD to pass various fd >= 0 checks.
+		 * This fd == 0 will not be used with any syscall and will be reset to -1 eventually.
+		 */
+		map->fd = 0;
+	} else {
+		map->fd = bpf_map_create(def->type, map_name,
+					 def->key_size, def->value_size,
+					 def->max_entries, &create_attr);
+	}
+	if (map->fd < 0 && (create_attr.btf_key_type_id ||
+			    create_attr.btf_value_type_id)) {
+		char *cp, errmsg[STRERR_BUFSIZE];
+
+		err = -errno;
+		cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+		pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
+			map->name, cp, err);
+		create_attr.btf_fd = 0;
+		create_attr.btf_key_type_id = 0;
+		create_attr.btf_value_type_id = 0;
+		map->btf_key_type_id = 0;
+		map->btf_value_type_id = 0;
+		map->fd = bpf_map_create(def->type, map_name,
+					 def->key_size, def->value_size,
+					 def->max_entries, &create_attr);
+	}
+
+	err = map->fd < 0 ? -errno : 0;
+
+	if (bpf_map_type__is_map_in_map(def->type) && map->inner_map) {
+		if (obj->gen_loader)
+			map->inner_map->fd = -1;
+		bpf_map__destroy(map->inner_map);
+		zfree(&map->inner_map);
+	}
+
+	return err;
+}
+
+static int init_map_in_map_slots(struct bpf_object *obj, struct bpf_map *map)
+{
+	const struct bpf_map *targ_map;
+	unsigned int i;
+	int fd, err = 0;
+
+	for (i = 0; i < map->init_slots_sz; i++) {
+		if (!map->init_slots[i])
+			continue;
+
+		targ_map = map->init_slots[i];
+		fd = bpf_map__fd(targ_map);
+
+		if (obj->gen_loader) {
+			bpf_gen__populate_outer_map(obj->gen_loader,
+						    map - obj->maps, i,
+						    targ_map - obj->maps);
+		} else {
+			err = bpf_map_update_elem(map->fd, &i, &fd, 0);
+		}
+		if (err) {
+			err = -errno;
+			pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",
+				map->name, i, targ_map->name, fd, err);
+			return err;
+		}
+		pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
+			 map->name, i, targ_map->name, fd);
+	}
+
+	zfree(&map->init_slots);
+	map->init_slots_sz = 0;
+
+	return 0;
+}
+
+static int init_prog_array_slots(struct bpf_object *obj, struct bpf_map *map)
+{
+	const struct bpf_program *targ_prog;
+	unsigned int i;
+	int fd, err;
+
+	if (obj->gen_loader)
+		return -ENOTSUP;
+
+	for (i = 0; i < map->init_slots_sz; i++) {
+		if (!map->init_slots[i])
+			continue;
+
+		targ_prog = map->init_slots[i];
+		fd = bpf_program__fd(targ_prog);
+
+		err = bpf_map_update_elem(map->fd, &i, &fd, 0);
+		if (err) {
+			err = -errno;
+			pr_warn("map '%s': failed to initialize slot [%d] to prog '%s' fd=%d: %d\n",
+				map->name, i, targ_prog->name, fd, err);
+			return err;
+		}
+		pr_debug("map '%s': slot [%d] set to prog '%s' fd=%d\n",
+			 map->name, i, targ_prog->name, fd);
+	}
+
+	zfree(&map->init_slots);
+	map->init_slots_sz = 0;
+
+	return 0;
+}
+
+static int bpf_object_init_prog_arrays(struct bpf_object *obj)
+{
+	struct bpf_map *map;
+	int i, err;
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		map = &obj->maps[i];
+
+		if (!map->init_slots_sz || map->def.type != BPF_MAP_TYPE_PROG_ARRAY)
+			continue;
+
+		err = init_prog_array_slots(obj, map);
+		if (err < 0) {
+			zclose(map->fd);
+			return err;
+		}
+	}
+	return 0;
+}
+
+static int map_set_def_max_entries(struct bpf_map *map)
+{
+	if (map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !map->def.max_entries) {
+		int nr_cpus;
+
+		nr_cpus = libbpf_num_possible_cpus();
+		if (nr_cpus < 0) {
+			pr_warn("map '%s': failed to determine number of system CPUs: %d\n",
+				map->name, nr_cpus);
+			return nr_cpus;
+		}
+		pr_debug("map '%s': setting size to %d\n", map->name, nr_cpus);
+		map->def.max_entries = nr_cpus;
+	}
+
+	return 0;
+}
+
+static int
+bpf_object__create_maps(struct bpf_object *obj)
+{
+	struct bpf_map *map;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	unsigned int i, j;
+	int err;
+	bool retried;
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		map = &obj->maps[i];
+
+		/* To support old kernels, we skip creating global data maps
+		 * (.rodata, .data, .kconfig, etc); later on, during program
+		 * loading, if we detect that at least one of the to-be-loaded
+		 * programs is referencing any global data map, we'll error
+		 * out with program name and relocation index logged.
+		 * This approach allows to accommodate Clang emitting
+		 * unnecessary .rodata.str1.1 sections for string literals,
+		 * but also it allows to have CO-RE applications that use
+		 * global variables in some of BPF programs, but not others.
+		 * If those global variable-using programs are not loaded at
+		 * runtime due to bpf_program__set_autoload(prog, false),
+		 * bpf_object loading will succeed just fine even on old
+		 * kernels.
+		 */
+		if (bpf_map__is_internal(map) && !kernel_supports(obj, FEAT_GLOBAL_DATA))
+			map->autocreate = false;
+
+		if (!map->autocreate) {
+			pr_debug("map '%s': skipped auto-creating...\n", map->name);
+			continue;
+		}
+
+		err = map_set_def_max_entries(map);
+		if (err)
+			goto err_out;
+
+		retried = false;
+retry:
+		if (map->pin_path) {
+			err = bpf_object__reuse_map(map);
+			if (err) {
+				pr_warn("map '%s': error reusing pinned map\n",
+					map->name);
+				goto err_out;
+			}
+			if (retried && map->fd < 0) {
+				pr_warn("map '%s': cannot find pinned map\n",
+					map->name);
+				err = -ENOENT;
+				goto err_out;
+			}
+		}
+
+		if (map->fd >= 0) {
+			pr_debug("map '%s': skipping creation (preset fd=%d)\n",
+				 map->name, map->fd);
+		} else {
+			err = bpf_object__create_map(obj, map, false);
+			if (err)
+				goto err_out;
+
+			pr_debug("map '%s': created successfully, fd=%d\n",
+				 map->name, map->fd);
+
+			if (bpf_map__is_internal(map)) {
+				err = bpf_object__populate_internal_map(obj, map);
+				if (err < 0) {
+					zclose(map->fd);
+					goto err_out;
+				}
+			}
+
+			if (map->init_slots_sz && map->def.type != BPF_MAP_TYPE_PROG_ARRAY) {
+				err = init_map_in_map_slots(obj, map);
+				if (err < 0) {
+					zclose(map->fd);
+					goto err_out;
+				}
+			}
+		}
+
+		if (map->pin_path && !map->pinned) {
+			err = bpf_map__pin(map, NULL);
+			if (err) {
+				zclose(map->fd);
+				if (!retried && err == -EEXIST) {
+					retried = true;
+					goto retry;
+				}
+				pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
+					map->name, map->pin_path, err);
+				goto err_out;
+			}
+		}
+	}
+
+	return 0;
+
+err_out:
+	cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+	pr_warn("map '%s': failed to create: %s(%d)\n", map->name, cp, err);
+	pr_perm_msg(err);
+	for (j = 0; j < i; j++)
+		zclose(obj->maps[j].fd);
+	return err;
+}
+
+static bool bpf_core_is_flavor_sep(const char *s)
+{
+	/* check X___Y name pattern, where X and Y are not underscores */
+	return s[0] != '_' &&				      /* X */
+	       s[1] == '_' && s[2] == '_' && s[3] == '_' &&   /* ___ */
+	       s[4] != '_';				      /* Y */
+}
+
+/* Given 'some_struct_name___with_flavor' return the length of a name prefix
+ * before last triple underscore. Struct name part after last triple
+ * underscore is ignored by BPF CO-RE relocation during relocation matching.
+ */
+size_t bpf_core_essential_name_len(const char *name)
+{
+	size_t n = strlen(name);
+	int i;
+
+	for (i = n - 5; i >= 0; i--) {
+		if (bpf_core_is_flavor_sep(name + i))
+			return i + 1;
+	}
+	return n;
+}
+
+void bpf_core_free_cands(struct bpf_core_cand_list *cands)
+{
+	if (!cands)
+		return;
+
+	free(cands->cands);
+	free(cands);
+}
+
+int bpf_core_add_cands(struct bpf_core_cand *local_cand,
+		       size_t local_essent_len,
+		       const struct btf *targ_btf,
+		       const char *targ_btf_name,
+		       int targ_start_id,
+		       struct bpf_core_cand_list *cands)
+{
+	struct bpf_core_cand *new_cands, *cand;
+	const struct btf_type *t, *local_t;
+	const char *targ_name, *local_name;
+	size_t targ_essent_len;
+	int n, i;
+
+	local_t = btf__type_by_id(local_cand->btf, local_cand->id);
+	local_name = btf__str_by_offset(local_cand->btf, local_t->name_off);
+
+	n = btf__type_cnt(targ_btf);
+	for (i = targ_start_id; i < n; i++) {
+		t = btf__type_by_id(targ_btf, i);
+		if (!btf_kind_core_compat(t, local_t))
+			continue;
+
+		targ_name = btf__name_by_offset(targ_btf, t->name_off);
+		if (str_is_empty(targ_name))
+			continue;
+
+		targ_essent_len = bpf_core_essential_name_len(targ_name);
+		if (targ_essent_len != local_essent_len)
+			continue;
+
+		if (strncmp(local_name, targ_name, local_essent_len) != 0)
+			continue;
+
+		pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s in [%s]\n",
+			 local_cand->id, btf_kind_str(local_t),
+			 local_name, i, btf_kind_str(t), targ_name,
+			 targ_btf_name);
+		new_cands = libbpf_reallocarray(cands->cands, cands->len + 1,
+					      sizeof(*cands->cands));
+		if (!new_cands)
+			return -ENOMEM;
+
+		cand = &new_cands[cands->len];
+		cand->btf = targ_btf;
+		cand->id = i;
+
+		cands->cands = new_cands;
+		cands->len++;
+	}
+	return 0;
+}
+
+static int load_module_btfs(struct bpf_object *obj)
+{
+	struct bpf_btf_info info;
+	struct module_btf *mod_btf;
+	struct btf *btf;
+	char name[64];
+	__u32 id = 0, len;
+	int err, fd;
+
+	if (obj->btf_modules_loaded)
+		return 0;
+
+	if (obj->gen_loader)
+		return 0;
+
+	/* don't do this again, even if we find no module BTFs */
+	obj->btf_modules_loaded = true;
+
+	/* kernel too old to support module BTFs */
+	if (!kernel_supports(obj, FEAT_MODULE_BTF))
+		return 0;
+
+	while (true) {
+		err = bpf_btf_get_next_id(id, &id);
+		if (err && errno == ENOENT)
+			return 0;
+		if (err) {
+			err = -errno;
+			pr_warn("failed to iterate BTF objects: %d\n", err);
+			return err;
+		}
+
+		fd = bpf_btf_get_fd_by_id(id);
+		if (fd < 0) {
+			if (errno == ENOENT)
+				continue; /* expected race: BTF was unloaded */
+			err = -errno;
+			pr_warn("failed to get BTF object #%d FD: %d\n", id, err);
+			return err;
+		}
+
+		len = sizeof(info);
+		memset(&info, 0, sizeof(info));
+		info.name = ptr_to_u64(name);
+		info.name_len = sizeof(name);
+
+		err = bpf_obj_get_info_by_fd(fd, &info, &len);
+		if (err) {
+			err = -errno;
+			pr_warn("failed to get BTF object #%d info: %d\n", id, err);
+			goto err_out;
+		}
+
+		/* ignore non-module BTFs */
+		if (!info.kernel_btf || strcmp(name, "vmlinux") == 0) {
+			close(fd);
+			continue;
+		}
+
+		btf = btf_get_from_fd(fd, obj->btf_vmlinux);
+		err = libbpf_get_error(btf);
+		if (err) {
+			pr_warn("failed to load module [%s]'s BTF object #%d: %d\n",
+				name, id, err);
+			goto err_out;
+		}
+
+		err = libbpf_ensure_mem((void **)&obj->btf_modules, &obj->btf_module_cap,
+					sizeof(*obj->btf_modules), obj->btf_module_cnt + 1);
+		if (err)
+			goto err_out;
+
+		mod_btf = &obj->btf_modules[obj->btf_module_cnt++];
+
+		mod_btf->btf = btf;
+		mod_btf->id = id;
+		mod_btf->fd = fd;
+		mod_btf->name = strdup(name);
+		if (!mod_btf->name) {
+			err = -ENOMEM;
+			goto err_out;
+		}
+		continue;
+
+err_out:
+		close(fd);
+		return err;
+	}
+
+	return 0;
+}
+
+static struct bpf_core_cand_list *
+bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id)
+{
+	struct bpf_core_cand local_cand = {};
+	struct bpf_core_cand_list *cands;
+	const struct btf *main_btf;
+	const struct btf_type *local_t;
+	const char *local_name;
+	size_t local_essent_len;
+	int err, i;
+
+	local_cand.btf = local_btf;
+	local_cand.id = local_type_id;
+	local_t = btf__type_by_id(local_btf, local_type_id);
+	if (!local_t)
+		return ERR_PTR(-EINVAL);
+
+	local_name = btf__name_by_offset(local_btf, local_t->name_off);
+	if (str_is_empty(local_name))
+		return ERR_PTR(-EINVAL);
+	local_essent_len = bpf_core_essential_name_len(local_name);
+
+	cands = calloc(1, sizeof(*cands));
+	if (!cands)
+		return ERR_PTR(-ENOMEM);
+
+	/* Attempt to find target candidates in vmlinux BTF first */
+	main_btf = obj->btf_vmlinux_override ?: obj->btf_vmlinux;
+	err = bpf_core_add_cands(&local_cand, local_essent_len, main_btf, "vmlinux", 1, cands);
+	if (err)
+		goto err_out;
+
+	/* if vmlinux BTF has any candidate, don't got for module BTFs */
+	if (cands->len)
+		return cands;
+
+	/* if vmlinux BTF was overridden, don't attempt to load module BTFs */
+	if (obj->btf_vmlinux_override)
+		return cands;
+
+	/* now look through module BTFs, trying to still find candidates */
+	err = load_module_btfs(obj);
+	if (err)
+		goto err_out;
+
+	for (i = 0; i < obj->btf_module_cnt; i++) {
+		err = bpf_core_add_cands(&local_cand, local_essent_len,
+					 obj->btf_modules[i].btf,
+					 obj->btf_modules[i].name,
+					 btf__type_cnt(obj->btf_vmlinux),
+					 cands);
+		if (err)
+			goto err_out;
+	}
+
+	return cands;
+err_out:
+	bpf_core_free_cands(cands);
+	return ERR_PTR(err);
+}
+
+/* Check local and target types for compatibility. This check is used for
+ * type-based CO-RE relocations and follow slightly different rules than
+ * field-based relocations. This function assumes that root types were already
+ * checked for name match. Beyond that initial root-level name check, names
+ * are completely ignored. Compatibility rules are as follows:
+ *   - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs are considered compatible, but
+ *     kind should match for local and target types (i.e., STRUCT is not
+ *     compatible with UNION);
+ *   - for ENUMs, the size is ignored;
+ *   - for INT, size and signedness are ignored;
+ *   - for ARRAY, dimensionality is ignored, element types are checked for
+ *     compatibility recursively;
+ *   - CONST/VOLATILE/RESTRICT modifiers are ignored;
+ *   - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
+ *   - FUNC_PROTOs are compatible if they have compatible signature: same
+ *     number of input args and compatible return and argument types.
+ * These rules are not set in stone and probably will be adjusted as we get
+ * more experience with using BPF CO-RE relocations.
+ */
+int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
+			      const struct btf *targ_btf, __u32 targ_id)
+{
+	return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id, 32);
+}
+
+int bpf_core_types_match(const struct btf *local_btf, __u32 local_id,
+			 const struct btf *targ_btf, __u32 targ_id)
+{
+	return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false, 32);
+}
+
+static size_t bpf_core_hash_fn(const long key, void *ctx)
+{
+	return key;
+}
+
+static bool bpf_core_equal_fn(const long k1, const long k2, void *ctx)
+{
+	return k1 == k2;
+}
+
+static int record_relo_core(struct bpf_program *prog,
+			    const struct bpf_core_relo *core_relo, int insn_idx)
+{
+	struct reloc_desc *relos, *relo;
+
+	relos = libbpf_reallocarray(prog->reloc_desc,
+				    prog->nr_reloc + 1, sizeof(*relos));
+	if (!relos)
+		return -ENOMEM;
+	relo = &relos[prog->nr_reloc];
+	relo->type = RELO_CORE;
+	relo->insn_idx = insn_idx;
+	relo->core_relo = core_relo;
+	prog->reloc_desc = relos;
+	prog->nr_reloc++;
+	return 0;
+}
+
+static const struct bpf_core_relo *find_relo_core(struct bpf_program *prog, int insn_idx)
+{
+	struct reloc_desc *relo;
+	int i;
+
+	for (i = 0; i < prog->nr_reloc; i++) {
+		relo = &prog->reloc_desc[i];
+		if (relo->type != RELO_CORE || relo->insn_idx != insn_idx)
+			continue;
+
+		return relo->core_relo;
+	}
+
+	return NULL;
+}
+
+static int bpf_core_resolve_relo(struct bpf_program *prog,
+				 const struct bpf_core_relo *relo,
+				 int relo_idx,
+				 const struct btf *local_btf,
+				 struct hashmap *cand_cache,
+				 struct bpf_core_relo_res *targ_res)
+{
+	struct bpf_core_spec specs_scratch[3] = {};
+	struct bpf_core_cand_list *cands = NULL;
+	const char *prog_name = prog->name;
+	const struct btf_type *local_type;
+	const char *local_name;
+	__u32 local_id = relo->type_id;
+	int err;
+
+	local_type = btf__type_by_id(local_btf, local_id);
+	if (!local_type)
+		return -EINVAL;
+
+	local_name = btf__name_by_offset(local_btf, local_type->name_off);
+	if (!local_name)
+		return -EINVAL;
+
+	if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
+	    !hashmap__find(cand_cache, local_id, &cands)) {
+		cands = bpf_core_find_cands(prog->obj, local_btf, local_id);
+		if (IS_ERR(cands)) {
+			pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n",
+				prog_name, relo_idx, local_id, btf_kind_str(local_type),
+				local_name, PTR_ERR(cands));
+			return PTR_ERR(cands);
+		}
+		err = hashmap__set(cand_cache, local_id, cands, NULL, NULL);
+		if (err) {
+			bpf_core_free_cands(cands);
+			return err;
+		}
+	}
+
+	return bpf_core_calc_relo_insn(prog_name, relo, relo_idx, local_btf, cands, specs_scratch,
+				       targ_res);
+}
+
+static int
+bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
+{
+	const struct btf_ext_info_sec *sec;
+	struct bpf_core_relo_res targ_res;
+	const struct bpf_core_relo *rec;
+	const struct btf_ext_info *seg;
+	struct hashmap_entry *entry;
+	struct hashmap *cand_cache = NULL;
+	struct bpf_program *prog;
+	struct bpf_insn *insn;
+	const char *sec_name;
+	int i, err = 0, insn_idx, sec_idx, sec_num;
+
+	if (obj->btf_ext->core_relo_info.len == 0)
+		return 0;
+
+	if (targ_btf_path) {
+		obj->btf_vmlinux_override = btf__parse(targ_btf_path, NULL);
+		err = libbpf_get_error(obj->btf_vmlinux_override);
+		if (err) {
+			pr_warn("failed to parse target BTF: %d\n", err);
+			return err;
+		}
+	}
+
+	cand_cache = hashmap__new(bpf_core_hash_fn, bpf_core_equal_fn, NULL);
+	if (IS_ERR(cand_cache)) {
+		err = PTR_ERR(cand_cache);
+		goto out;
+	}
+
+	seg = &obj->btf_ext->core_relo_info;
+	sec_num = 0;
+	for_each_btf_ext_sec(seg, sec) {
+		sec_idx = seg->sec_idxs[sec_num];
+		sec_num++;
+
+		sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
+		if (str_is_empty(sec_name)) {
+			err = -EINVAL;
+			goto out;
+		}
+
+		pr_debug("sec '%s': found %d CO-RE relocations\n", sec_name, sec->num_info);
+
+		for_each_btf_ext_rec(seg, sec, i, rec) {
+			if (rec->insn_off % BPF_INSN_SZ)
+				return -EINVAL;
+			insn_idx = rec->insn_off / BPF_INSN_SZ;
+			prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
+			if (!prog) {
+				/* When __weak subprog is "overridden" by another instance
+				 * of the subprog from a different object file, linker still
+				 * appends all the .BTF.ext info that used to belong to that
+				 * eliminated subprogram.
+				 * This is similar to what x86-64 linker does for relocations.
+				 * So just ignore such relocations just like we ignore
+				 * subprog instructions when discovering subprograms.
+				 */
+				pr_debug("sec '%s': skipping CO-RE relocation #%d for insn #%d belonging to eliminated weak subprogram\n",
+					 sec_name, i, insn_idx);
+				continue;
+			}
+			/* no need to apply CO-RE relocation if the program is
+			 * not going to be loaded
+			 */
+			if (!prog->autoload)
+				continue;
+
+			/* adjust insn_idx from section frame of reference to the local
+			 * program's frame of reference; (sub-)program code is not yet
+			 * relocated, so it's enough to just subtract in-section offset
+			 */
+			insn_idx = insn_idx - prog->sec_insn_off;
+			if (insn_idx >= prog->insns_cnt)
+				return -EINVAL;
+			insn = &prog->insns[insn_idx];
+
+			err = record_relo_core(prog, rec, insn_idx);
+			if (err) {
+				pr_warn("prog '%s': relo #%d: failed to record relocation: %d\n",
+					prog->name, i, err);
+				goto out;
+			}
+
+			if (prog->obj->gen_loader)
+				continue;
+
+			err = bpf_core_resolve_relo(prog, rec, i, obj->btf, cand_cache, &targ_res);
+			if (err) {
+				pr_warn("prog '%s': relo #%d: failed to relocate: %d\n",
+					prog->name, i, err);
+				goto out;
+			}
+
+			err = bpf_core_patch_insn(prog->name, insn, insn_idx, rec, i, &targ_res);
+			if (err) {
+				pr_warn("prog '%s': relo #%d: failed to patch insn #%u: %d\n",
+					prog->name, i, insn_idx, err);
+				goto out;
+			}
+		}
+	}
+
+out:
+	/* obj->btf_vmlinux and module BTFs are freed after object load */
+	btf__free(obj->btf_vmlinux_override);
+	obj->btf_vmlinux_override = NULL;
+
+	if (!IS_ERR_OR_NULL(cand_cache)) {
+		hashmap__for_each_entry(cand_cache, entry, i) {
+			bpf_core_free_cands(entry->pvalue);
+		}
+		hashmap__free(cand_cache);
+	}
+	return err;
+}
+
+/* base map load ldimm64 special constant, used also for log fixup logic */
+#define MAP_LDIMM64_POISON_BASE 2001000000
+#define MAP_LDIMM64_POISON_PFX "200100"
+
+static void poison_map_ldimm64(struct bpf_program *prog, int relo_idx,
+			       int insn_idx, struct bpf_insn *insn,
+			       int map_idx, const struct bpf_map *map)
+{
+	int i;
+
+	pr_debug("prog '%s': relo #%d: poisoning insn #%d that loads map #%d '%s'\n",
+		 prog->name, relo_idx, insn_idx, map_idx, map->name);
+
+	/* we turn single ldimm64 into two identical invalid calls */
+	for (i = 0; i < 2; i++) {
+		insn->code = BPF_JMP | BPF_CALL;
+		insn->dst_reg = 0;
+		insn->src_reg = 0;
+		insn->off = 0;
+		/* if this instruction is reachable (not a dead code),
+		 * verifier will complain with something like:
+		 * invalid func unknown#2001000123
+		 * where lower 123 is map index into obj->maps[] array
+		 */
+		insn->imm = MAP_LDIMM64_POISON_BASE + map_idx;
+
+		insn++;
+	}
+}
+
+/* Relocate data references within program code:
+ *  - map references;
+ *  - global variable references;
+ *  - extern references.
+ */
+static int
+bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
+{
+	int i;
+
+	for (i = 0; i < prog->nr_reloc; i++) {
+		struct reloc_desc *relo = &prog->reloc_desc[i];
+		struct bpf_insn *insn = &prog->insns[relo->insn_idx];
+		const struct bpf_map *map;
+		struct extern_desc *ext;
+
+		switch (relo->type) {
+		case RELO_LD64:
+			map = &obj->maps[relo->map_idx];
+			if (obj->gen_loader) {
+				insn[0].src_reg = BPF_PSEUDO_MAP_IDX;
+				insn[0].imm = relo->map_idx;
+			} else if (map->autocreate) {
+				insn[0].src_reg = BPF_PSEUDO_MAP_FD;
+				insn[0].imm = map->fd;
+			} else {
+				poison_map_ldimm64(prog, i, relo->insn_idx, insn,
+						   relo->map_idx, map);
+			}
+			break;
+		case RELO_DATA:
+			map = &obj->maps[relo->map_idx];
+			insn[1].imm = insn[0].imm + relo->sym_off;
+			if (obj->gen_loader) {
+				insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
+				insn[0].imm = relo->map_idx;
+			} else if (map->autocreate) {
+				insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
+				insn[0].imm = map->fd;
+			} else {
+				poison_map_ldimm64(prog, i, relo->insn_idx, insn,
+						   relo->map_idx, map);
+			}
+			break;
+		case RELO_EXTERN_VAR:
+			ext = &obj->externs[relo->sym_off];
+			if (ext->type == EXT_KCFG) {
+				if (obj->gen_loader) {
+					insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
+					insn[0].imm = obj->kconfig_map_idx;
+				} else {
+					insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
+					insn[0].imm = obj->maps[obj->kconfig_map_idx].fd;
+				}
+				insn[1].imm = ext->kcfg.data_off;
+			} else /* EXT_KSYM */ {
+				if (ext->ksym.type_id && ext->is_set) { /* typed ksyms */
+					insn[0].src_reg = BPF_PSEUDO_BTF_ID;
+					insn[0].imm = ext->ksym.kernel_btf_id;
+					insn[1].imm = ext->ksym.kernel_btf_obj_fd;
+				} else { /* typeless ksyms or unresolved typed ksyms */
+					insn[0].imm = (__u32)ext->ksym.addr;
+					insn[1].imm = ext->ksym.addr >> 32;
+				}
+			}
+			break;
+		case RELO_EXTERN_FUNC:
+			ext = &obj->externs[relo->sym_off];
+			insn[0].src_reg = BPF_PSEUDO_KFUNC_CALL;
+			if (ext->is_set) {
+				insn[0].imm = ext->ksym.kernel_btf_id;
+				insn[0].off = ext->ksym.btf_fd_idx;
+			} else { /* unresolved weak kfunc */
+				insn[0].imm = 0;
+				insn[0].off = 0;
+			}
+			break;
+		case RELO_SUBPROG_ADDR:
+			if (insn[0].src_reg != BPF_PSEUDO_FUNC) {
+				pr_warn("prog '%s': relo #%d: bad insn\n",
+					prog->name, i);
+				return -EINVAL;
+			}
+			/* handled already */
+			break;
+		case RELO_CALL:
+			/* handled already */
+			break;
+		case RELO_CORE:
+			/* will be handled by bpf_program_record_relos() */
+			break;
+		default:
+			pr_warn("prog '%s': relo #%d: bad relo type %d\n",
+				prog->name, i, relo->type);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int adjust_prog_btf_ext_info(const struct bpf_object *obj,
+				    const struct bpf_program *prog,
+				    const struct btf_ext_info *ext_info,
+				    void **prog_info, __u32 *prog_rec_cnt,
+				    __u32 *prog_rec_sz)
+{
+	void *copy_start = NULL, *copy_end = NULL;
+	void *rec, *rec_end, *new_prog_info;
+	const struct btf_ext_info_sec *sec;
+	size_t old_sz, new_sz;
+	int i, sec_num, sec_idx, off_adj;
+
+	sec_num = 0;
+	for_each_btf_ext_sec(ext_info, sec) {
+		sec_idx = ext_info->sec_idxs[sec_num];
+		sec_num++;
+		if (prog->sec_idx != sec_idx)
+			continue;
+
+		for_each_btf_ext_rec(ext_info, sec, i, rec) {
+			__u32 insn_off = *(__u32 *)rec / BPF_INSN_SZ;
+
+			if (insn_off < prog->sec_insn_off)
+				continue;
+			if (insn_off >= prog->sec_insn_off + prog->sec_insn_cnt)
+				break;
+
+			if (!copy_start)
+				copy_start = rec;
+			copy_end = rec + ext_info->rec_size;
+		}
+
+		if (!copy_start)
+			return -ENOENT;
+
+		/* append func/line info of a given (sub-)program to the main
+		 * program func/line info
+		 */
+		old_sz = (size_t)(*prog_rec_cnt) * ext_info->rec_size;
+		new_sz = old_sz + (copy_end - copy_start);
+		new_prog_info = realloc(*prog_info, new_sz);
+		if (!new_prog_info)
+			return -ENOMEM;
+		*prog_info = new_prog_info;
+		*prog_rec_cnt = new_sz / ext_info->rec_size;
+		memcpy(new_prog_info + old_sz, copy_start, copy_end - copy_start);
+
+		/* Kernel instruction offsets are in units of 8-byte
+		 * instructions, while .BTF.ext instruction offsets generated
+		 * by Clang are in units of bytes. So convert Clang offsets
+		 * into kernel offsets and adjust offset according to program
+		 * relocated position.
+		 */
+		off_adj = prog->sub_insn_off - prog->sec_insn_off;
+		rec = new_prog_info + old_sz;
+		rec_end = new_prog_info + new_sz;
+		for (; rec < rec_end; rec += ext_info->rec_size) {
+			__u32 *insn_off = rec;
+
+			*insn_off = *insn_off / BPF_INSN_SZ + off_adj;
+		}
+		*prog_rec_sz = ext_info->rec_size;
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+static int
+reloc_prog_func_and_line_info(const struct bpf_object *obj,
+			      struct bpf_program *main_prog,
+			      const struct bpf_program *prog)
+{
+	int err;
+
+	/* no .BTF.ext relocation if .BTF.ext is missing or kernel doesn't
+	 * supprot func/line info
+	 */
+	if (!obj->btf_ext || !kernel_supports(obj, FEAT_BTF_FUNC))
+		return 0;
+
+	/* only attempt func info relocation if main program's func_info
+	 * relocation was successful
+	 */
+	if (main_prog != prog && !main_prog->func_info)
+		goto line_info;
+
+	err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->func_info,
+				       &main_prog->func_info,
+				       &main_prog->func_info_cnt,
+				       &main_prog->func_info_rec_size);
+	if (err) {
+		if (err != -ENOENT) {
+			pr_warn("prog '%s': error relocating .BTF.ext function info: %d\n",
+				prog->name, err);
+			return err;
+		}
+		if (main_prog->func_info) {
+			/*
+			 * Some info has already been found but has problem
+			 * in the last btf_ext reloc. Must have to error out.
+			 */
+			pr_warn("prog '%s': missing .BTF.ext function info.\n", prog->name);
+			return err;
+		}
+		/* Have problem loading the very first info. Ignore the rest. */
+		pr_warn("prog '%s': missing .BTF.ext function info for the main program, skipping all of .BTF.ext func info.\n",
+			prog->name);
+	}
+
+line_info:
+	/* don't relocate line info if main program's relocation failed */
+	if (main_prog != prog && !main_prog->line_info)
+		return 0;
+
+	err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->line_info,
+				       &main_prog->line_info,
+				       &main_prog->line_info_cnt,
+				       &main_prog->line_info_rec_size);
+	if (err) {
+		if (err != -ENOENT) {
+			pr_warn("prog '%s': error relocating .BTF.ext line info: %d\n",
+				prog->name, err);
+			return err;
+		}
+		if (main_prog->line_info) {
+			/*
+			 * Some info has already been found but has problem
+			 * in the last btf_ext reloc. Must have to error out.
+			 */
+			pr_warn("prog '%s': missing .BTF.ext line info.\n", prog->name);
+			return err;
+		}
+		/* Have problem loading the very first info. Ignore the rest. */
+		pr_warn("prog '%s': missing .BTF.ext line info for the main program, skipping all of .BTF.ext line info.\n",
+			prog->name);
+	}
+	return 0;
+}
+
+static int cmp_relo_by_insn_idx(const void *key, const void *elem)
+{
+	size_t insn_idx = *(const size_t *)key;
+	const struct reloc_desc *relo = elem;
+
+	if (insn_idx == relo->insn_idx)
+		return 0;
+	return insn_idx < relo->insn_idx ? -1 : 1;
+}
+
+static struct reloc_desc *find_prog_insn_relo(const struct bpf_program *prog, size_t insn_idx)
+{
+	if (!prog->nr_reloc)
+		return NULL;
+	return bsearch(&insn_idx, prog->reloc_desc, prog->nr_reloc,
+		       sizeof(*prog->reloc_desc), cmp_relo_by_insn_idx);
+}
+
+static int append_subprog_relos(struct bpf_program *main_prog, struct bpf_program *subprog)
+{
+	int new_cnt = main_prog->nr_reloc + subprog->nr_reloc;
+	struct reloc_desc *relos;
+	int i;
+
+	if (main_prog == subprog)
+		return 0;
+	relos = libbpf_reallocarray(main_prog->reloc_desc, new_cnt, sizeof(*relos));
+	if (!relos)
+		return -ENOMEM;
+	if (subprog->nr_reloc)
+		memcpy(relos + main_prog->nr_reloc, subprog->reloc_desc,
+		       sizeof(*relos) * subprog->nr_reloc);
+
+	for (i = main_prog->nr_reloc; i < new_cnt; i++)
+		relos[i].insn_idx += subprog->sub_insn_off;
+	/* After insn_idx adjustment the 'relos' array is still sorted
+	 * by insn_idx and doesn't break bsearch.
+	 */
+	main_prog->reloc_desc = relos;
+	main_prog->nr_reloc = new_cnt;
+	return 0;
+}
+
+static int
+bpf_object__reloc_code(struct bpf_object *obj, struct bpf_program *main_prog,
+		       struct bpf_program *prog)
+{
+	size_t sub_insn_idx, insn_idx, new_cnt;
+	struct bpf_program *subprog;
+	struct bpf_insn *insns, *insn;
+	struct reloc_desc *relo;
+	int err;
+
+	err = reloc_prog_func_and_line_info(obj, main_prog, prog);
+	if (err)
+		return err;
+
+	for (insn_idx = 0; insn_idx < prog->sec_insn_cnt; insn_idx++) {
+		insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
+		if (!insn_is_subprog_call(insn) && !insn_is_pseudo_func(insn))
+			continue;
+
+		relo = find_prog_insn_relo(prog, insn_idx);
+		if (relo && relo->type == RELO_EXTERN_FUNC)
+			/* kfunc relocations will be handled later
+			 * in bpf_object__relocate_data()
+			 */
+			continue;
+		if (relo && relo->type != RELO_CALL && relo->type != RELO_SUBPROG_ADDR) {
+			pr_warn("prog '%s': unexpected relo for insn #%zu, type %d\n",
+				prog->name, insn_idx, relo->type);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		if (relo) {
+			/* sub-program instruction index is a combination of
+			 * an offset of a symbol pointed to by relocation and
+			 * call instruction's imm field; for global functions,
+			 * call always has imm = -1, but for static functions
+			 * relocation is against STT_SECTION and insn->imm
+			 * points to a start of a static function
+			 *
+			 * for subprog addr relocation, the relo->sym_off + insn->imm is
+			 * the byte offset in the corresponding section.
+			 */
+			if (relo->type == RELO_CALL)
+				sub_insn_idx = relo->sym_off / BPF_INSN_SZ + insn->imm + 1;
+			else
+				sub_insn_idx = (relo->sym_off + insn->imm) / BPF_INSN_SZ;
+		} else if (insn_is_pseudo_func(insn)) {
+			/*
+			 * RELO_SUBPROG_ADDR relo is always emitted even if both
+			 * functions are in the same section, so it shouldn't reach here.
+			 */
+			pr_warn("prog '%s': missing subprog addr relo for insn #%zu\n",
+				prog->name, insn_idx);
+			return -LIBBPF_ERRNO__RELOC;
+		} else {
+			/* if subprogram call is to a static function within
+			 * the same ELF section, there won't be any relocation
+			 * emitted, but it also means there is no additional
+			 * offset necessary, insns->imm is relative to
+			 * instruction's original position within the section
+			 */
+			sub_insn_idx = prog->sec_insn_off + insn_idx + insn->imm + 1;
+		}
+
+		/* we enforce that sub-programs should be in .text section */
+		subprog = find_prog_by_sec_insn(obj, obj->efile.text_shndx, sub_insn_idx);
+		if (!subprog) {
+			pr_warn("prog '%s': no .text section found yet sub-program call exists\n",
+				prog->name);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+
+		/* if it's the first call instruction calling into this
+		 * subprogram (meaning this subprog hasn't been processed
+		 * yet) within the context of current main program:
+		 *   - append it at the end of main program's instructions blog;
+		 *   - process is recursively, while current program is put on hold;
+		 *   - if that subprogram calls some other not yet processes
+		 *   subprogram, same thing will happen recursively until
+		 *   there are no more unprocesses subprograms left to append
+		 *   and relocate.
+		 */
+		if (subprog->sub_insn_off == 0) {
+			subprog->sub_insn_off = main_prog->insns_cnt;
+
+			new_cnt = main_prog->insns_cnt + subprog->insns_cnt;
+			insns = libbpf_reallocarray(main_prog->insns, new_cnt, sizeof(*insns));
+			if (!insns) {
+				pr_warn("prog '%s': failed to realloc prog code\n", main_prog->name);
+				return -ENOMEM;
+			}
+			main_prog->insns = insns;
+			main_prog->insns_cnt = new_cnt;
+
+			memcpy(main_prog->insns + subprog->sub_insn_off, subprog->insns,
+			       subprog->insns_cnt * sizeof(*insns));
+
+			pr_debug("prog '%s': added %zu insns from sub-prog '%s'\n",
+				 main_prog->name, subprog->insns_cnt, subprog->name);
+
+			/* The subprog insns are now appended. Append its relos too. */
+			err = append_subprog_relos(main_prog, subprog);
+			if (err)
+				return err;
+			err = bpf_object__reloc_code(obj, main_prog, subprog);
+			if (err)
+				return err;
+		}
+
+		/* main_prog->insns memory could have been re-allocated, so
+		 * calculate pointer again
+		 */
+		insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
+		/* calculate correct instruction position within current main
+		 * prog; each main prog can have a different set of
+		 * subprograms appended (potentially in different order as
+		 * well), so position of any subprog can be different for
+		 * different main programs
+		 */
+		insn->imm = subprog->sub_insn_off - (prog->sub_insn_off + insn_idx) - 1;
+
+		pr_debug("prog '%s': insn #%zu relocated, imm %d points to subprog '%s' (now at %zu offset)\n",
+			 prog->name, insn_idx, insn->imm, subprog->name, subprog->sub_insn_off);
+	}
+
+	return 0;
+}
+
+/*
+ * Relocate sub-program calls.
+ *
+ * Algorithm operates as follows. Each entry-point BPF program (referred to as
+ * main prog) is processed separately. For each subprog (non-entry functions,
+ * that can be called from either entry progs or other subprogs) gets their
+ * sub_insn_off reset to zero. This serves as indicator that this subprogram
+ * hasn't been yet appended and relocated within current main prog. Once its
+ * relocated, sub_insn_off will point at the position within current main prog
+ * where given subprog was appended. This will further be used to relocate all
+ * the call instructions jumping into this subprog.
+ *
+ * We start with main program and process all call instructions. If the call
+ * is into a subprog that hasn't been processed (i.e., subprog->sub_insn_off
+ * is zero), subprog instructions are appended at the end of main program's
+ * instruction array. Then main program is "put on hold" while we recursively
+ * process newly appended subprogram. If that subprogram calls into another
+ * subprogram that hasn't been appended, new subprogram is appended again to
+ * the *main* prog's instructions (subprog's instructions are always left
+ * untouched, as they need to be in unmodified state for subsequent main progs
+ * and subprog instructions are always sent only as part of a main prog) and
+ * the process continues recursively. Once all the subprogs called from a main
+ * prog or any of its subprogs are appended (and relocated), all their
+ * positions within finalized instructions array are known, so it's easy to
+ * rewrite call instructions with correct relative offsets, corresponding to
+ * desired target subprog.
+ *
+ * Its important to realize that some subprogs might not be called from some
+ * main prog and any of its called/used subprogs. Those will keep their
+ * subprog->sub_insn_off as zero at all times and won't be appended to current
+ * main prog and won't be relocated within the context of current main prog.
+ * They might still be used from other main progs later.
+ *
+ * Visually this process can be shown as below. Suppose we have two main
+ * programs mainA and mainB and BPF object contains three subprogs: subA,
+ * subB, and subC. mainA calls only subA, mainB calls only subC, but subA and
+ * subC both call subB:
+ *
+ *        +--------+ +-------+
+ *        |        v v       |
+ *     +--+---+ +--+-+-+ +---+--+
+ *     | subA | | subB | | subC |
+ *     +--+---+ +------+ +---+--+
+ *        ^                  ^
+ *        |                  |
+ *    +---+-------+   +------+----+
+ *    |   mainA   |   |   mainB   |
+ *    +-----------+   +-----------+
+ *
+ * We'll start relocating mainA, will find subA, append it and start
+ * processing sub A recursively:
+ *
+ *    +-----------+------+
+ *    |   mainA   | subA |
+ *    +-----------+------+
+ *
+ * At this point we notice that subB is used from subA, so we append it and
+ * relocate (there are no further subcalls from subB):
+ *
+ *    +-----------+------+------+
+ *    |   mainA   | subA | subB |
+ *    +-----------+------+------+
+ *
+ * At this point, we relocate subA calls, then go one level up and finish with
+ * relocatin mainA calls. mainA is done.
+ *
+ * For mainB process is similar but results in different order. We start with
+ * mainB and skip subA and subB, as mainB never calls them (at least
+ * directly), but we see subC is needed, so we append and start processing it:
+ *
+ *    +-----------+------+
+ *    |   mainB   | subC |
+ *    +-----------+------+
+ * Now we see subC needs subB, so we go back to it, append and relocate it:
+ *
+ *    +-----------+------+------+
+ *    |   mainB   | subC | subB |
+ *    +-----------+------+------+
+ *
+ * At this point we unwind recursion, relocate calls in subC, then in mainB.
+ */
+static int
+bpf_object__relocate_calls(struct bpf_object *obj, struct bpf_program *prog)
+{
+	struct bpf_program *subprog;
+	int i, err;
+
+	/* mark all subprogs as not relocated (yet) within the context of
+	 * current main program
+	 */
+	for (i = 0; i < obj->nr_programs; i++) {
+		subprog = &obj->programs[i];
+		if (!prog_is_subprog(obj, subprog))
+			continue;
+
+		subprog->sub_insn_off = 0;
+	}
+
+	err = bpf_object__reloc_code(obj, prog, prog);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static void
+bpf_object__free_relocs(struct bpf_object *obj)
+{
+	struct bpf_program *prog;
+	int i;
+
+	/* free up relocation descriptors */
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		zfree(&prog->reloc_desc);
+		prog->nr_reloc = 0;
+	}
+}
+
+static int cmp_relocs(const void *_a, const void *_b)
+{
+	const struct reloc_desc *a = _a;
+	const struct reloc_desc *b = _b;
+
+	if (a->insn_idx != b->insn_idx)
+		return a->insn_idx < b->insn_idx ? -1 : 1;
+
+	/* no two relocations should have the same insn_idx, but ... */
+	if (a->type != b->type)
+		return a->type < b->type ? -1 : 1;
+
+	return 0;
+}
+
+static void bpf_object__sort_relos(struct bpf_object *obj)
+{
+	int i;
+
+	for (i = 0; i < obj->nr_programs; i++) {
+		struct bpf_program *p = &obj->programs[i];
+
+		if (!p->nr_reloc)
+			continue;
+
+		qsort(p->reloc_desc, p->nr_reloc, sizeof(*p->reloc_desc), cmp_relocs);
+	}
+}
+
+static int
+bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
+{
+	struct bpf_program *prog;
+	size_t i, j;
+	int err;
+
+	if (obj->btf_ext) {
+		err = bpf_object__relocate_core(obj, targ_btf_path);
+		if (err) {
+			pr_warn("failed to perform CO-RE relocations: %d\n",
+				err);
+			return err;
+		}
+		bpf_object__sort_relos(obj);
+	}
+
+	/* Before relocating calls pre-process relocations and mark
+	 * few ld_imm64 instructions that points to subprogs.
+	 * Otherwise bpf_object__reloc_code() later would have to consider
+	 * all ld_imm64 insns as relocation candidates. That would
+	 * reduce relocation speed, since amount of find_prog_insn_relo()
+	 * would increase and most of them will fail to find a relo.
+	 */
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		for (j = 0; j < prog->nr_reloc; j++) {
+			struct reloc_desc *relo = &prog->reloc_desc[j];
+			struct bpf_insn *insn = &prog->insns[relo->insn_idx];
+
+			/* mark the insn, so it's recognized by insn_is_pseudo_func() */
+			if (relo->type == RELO_SUBPROG_ADDR)
+				insn[0].src_reg = BPF_PSEUDO_FUNC;
+		}
+	}
+
+	/* relocate subprogram calls and append used subprograms to main
+	 * programs; each copy of subprogram code needs to be relocated
+	 * differently for each main program, because its code location might
+	 * have changed.
+	 * Append subprog relos to main programs to allow data relos to be
+	 * processed after text is completely relocated.
+	 */
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		/* sub-program's sub-calls are relocated within the context of
+		 * its main program only
+		 */
+		if (prog_is_subprog(obj, prog))
+			continue;
+		if (!prog->autoload)
+			continue;
+
+		err = bpf_object__relocate_calls(obj, prog);
+		if (err) {
+			pr_warn("prog '%s': failed to relocate calls: %d\n",
+				prog->name, err);
+			return err;
+		}
+	}
+	/* Process data relos for main programs */
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		if (prog_is_subprog(obj, prog))
+			continue;
+		if (!prog->autoload)
+			continue;
+		err = bpf_object__relocate_data(obj, prog);
+		if (err) {
+			pr_warn("prog '%s': failed to relocate data references: %d\n",
+				prog->name, err);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
+					    Elf64_Shdr *shdr, Elf_Data *data);
+
+static int bpf_object__collect_map_relos(struct bpf_object *obj,
+					 Elf64_Shdr *shdr, Elf_Data *data)
+{
+	const int bpf_ptr_sz = 8, host_ptr_sz = sizeof(void *);
+	int i, j, nrels, new_sz;
+	const struct btf_var_secinfo *vi = NULL;
+	const struct btf_type *sec, *var, *def;
+	struct bpf_map *map = NULL, *targ_map = NULL;
+	struct bpf_program *targ_prog = NULL;
+	bool is_prog_array, is_map_in_map;
+	const struct btf_member *member;
+	const char *name, *mname, *type;
+	unsigned int moff;
+	Elf64_Sym *sym;
+	Elf64_Rel *rel;
+	void *tmp;
+
+	if (!obj->efile.btf_maps_sec_btf_id || !obj->btf)
+		return -EINVAL;
+	sec = btf__type_by_id(obj->btf, obj->efile.btf_maps_sec_btf_id);
+	if (!sec)
+		return -EINVAL;
+
+	nrels = shdr->sh_size / shdr->sh_entsize;
+	for (i = 0; i < nrels; i++) {
+		rel = elf_rel_by_idx(data, i);
+		if (!rel) {
+			pr_warn(".maps relo #%d: failed to get ELF relo\n", i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info));
+		if (!sym) {
+			pr_warn(".maps relo #%d: symbol %zx not found\n",
+				i, (size_t)ELF64_R_SYM(rel->r_info));
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+		name = elf_sym_str(obj, sym->st_name) ?: "<?>";
+
+		pr_debug(".maps relo #%d: for %zd value %zd rel->r_offset %zu name %d ('%s')\n",
+			 i, (ssize_t)(rel->r_info >> 32), (size_t)sym->st_value,
+			 (size_t)rel->r_offset, sym->st_name, name);
+
+		for (j = 0; j < obj->nr_maps; j++) {
+			map = &obj->maps[j];
+			if (map->sec_idx != obj->efile.btf_maps_shndx)
+				continue;
+
+			vi = btf_var_secinfos(sec) + map->btf_var_idx;
+			if (vi->offset <= rel->r_offset &&
+			    rel->r_offset + bpf_ptr_sz <= vi->offset + vi->size)
+				break;
+		}
+		if (j == obj->nr_maps) {
+			pr_warn(".maps relo #%d: cannot find map '%s' at rel->r_offset %zu\n",
+				i, name, (size_t)rel->r_offset);
+			return -EINVAL;
+		}
+
+		is_map_in_map = bpf_map_type__is_map_in_map(map->def.type);
+		is_prog_array = map->def.type == BPF_MAP_TYPE_PROG_ARRAY;
+		type = is_map_in_map ? "map" : "prog";
+		if (is_map_in_map) {
+			if (sym->st_shndx != obj->efile.btf_maps_shndx) {
+				pr_warn(".maps relo #%d: '%s' isn't a BTF-defined map\n",
+					i, name);
+				return -LIBBPF_ERRNO__RELOC;
+			}
+			if (map->def.type == BPF_MAP_TYPE_HASH_OF_MAPS &&
+			    map->def.key_size != sizeof(int)) {
+				pr_warn(".maps relo #%d: hash-of-maps '%s' should have key size %zu.\n",
+					i, map->name, sizeof(int));
+				return -EINVAL;
+			}
+			targ_map = bpf_object__find_map_by_name(obj, name);
+			if (!targ_map) {
+				pr_warn(".maps relo #%d: '%s' isn't a valid map reference\n",
+					i, name);
+				return -ESRCH;
+			}
+		} else if (is_prog_array) {
+			targ_prog = bpf_object__find_program_by_name(obj, name);
+			if (!targ_prog) {
+				pr_warn(".maps relo #%d: '%s' isn't a valid program reference\n",
+					i, name);
+				return -ESRCH;
+			}
+			if (targ_prog->sec_idx != sym->st_shndx ||
+			    targ_prog->sec_insn_off * 8 != sym->st_value ||
+			    prog_is_subprog(obj, targ_prog)) {
+				pr_warn(".maps relo #%d: '%s' isn't an entry-point program\n",
+					i, name);
+				return -LIBBPF_ERRNO__RELOC;
+			}
+		} else {
+			return -EINVAL;
+		}
+
+		var = btf__type_by_id(obj->btf, vi->type);
+		def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
+		if (btf_vlen(def) == 0)
+			return -EINVAL;
+		member = btf_members(def) + btf_vlen(def) - 1;
+		mname = btf__name_by_offset(obj->btf, member->name_off);
+		if (strcmp(mname, "values"))
+			return -EINVAL;
+
+		moff = btf_member_bit_offset(def, btf_vlen(def) - 1) / 8;
+		if (rel->r_offset - vi->offset < moff)
+			return -EINVAL;
+
+		moff = rel->r_offset - vi->offset - moff;
+		/* here we use BPF pointer size, which is always 64 bit, as we
+		 * are parsing ELF that was built for BPF target
+		 */
+		if (moff % bpf_ptr_sz)
+			return -EINVAL;
+		moff /= bpf_ptr_sz;
+		if (moff >= map->init_slots_sz) {
+			new_sz = moff + 1;
+			tmp = libbpf_reallocarray(map->init_slots, new_sz, host_ptr_sz);
+			if (!tmp)
+				return -ENOMEM;
+			map->init_slots = tmp;
+			memset(map->init_slots + map->init_slots_sz, 0,
+			       (new_sz - map->init_slots_sz) * host_ptr_sz);
+			map->init_slots_sz = new_sz;
+		}
+		map->init_slots[moff] = is_map_in_map ? (void *)targ_map : (void *)targ_prog;
+
+		pr_debug(".maps relo #%d: map '%s' slot [%d] points to %s '%s'\n",
+			 i, map->name, moff, type, name);
+	}
+
+	return 0;
+}
+
+static int bpf_object__collect_relos(struct bpf_object *obj)
+{
+	int i, err;
+
+	for (i = 0; i < obj->efile.sec_cnt; i++) {
+		struct elf_sec_desc *sec_desc = &obj->efile.secs[i];
+		Elf64_Shdr *shdr;
+		Elf_Data *data;
+		int idx;
+
+		if (sec_desc->sec_type != SEC_RELO)
+			continue;
+
+		shdr = sec_desc->shdr;
+		data = sec_desc->data;
+		idx = shdr->sh_info;
+
+		if (shdr->sh_type != SHT_REL) {
+			pr_warn("internal error at %d\n", __LINE__);
+			return -LIBBPF_ERRNO__INTERNAL;
+		}
+
+		if (idx == obj->efile.st_ops_shndx)
+			err = bpf_object__collect_st_ops_relos(obj, shdr, data);
+		else if (idx == obj->efile.btf_maps_shndx)
+			err = bpf_object__collect_map_relos(obj, shdr, data);
+		else
+			err = bpf_object__collect_prog_relos(obj, shdr, data);
+		if (err)
+			return err;
+	}
+
+	bpf_object__sort_relos(obj);
+	return 0;
+}
+
+static bool insn_is_helper_call(struct bpf_insn *insn, enum bpf_func_id *func_id)
+{
+	if (BPF_CLASS(insn->code) == BPF_JMP &&
+	    BPF_OP(insn->code) == BPF_CALL &&
+	    BPF_SRC(insn->code) == BPF_K &&
+	    insn->src_reg == 0 &&
+	    insn->dst_reg == 0) {
+		    *func_id = insn->imm;
+		    return true;
+	}
+	return false;
+}
+
+static int bpf_object__sanitize_prog(struct bpf_object *obj, struct bpf_program *prog)
+{
+	struct bpf_insn *insn = prog->insns;
+	enum bpf_func_id func_id;
+	int i;
+
+	if (obj->gen_loader)
+		return 0;
+
+	for (i = 0; i < prog->insns_cnt; i++, insn++) {
+		if (!insn_is_helper_call(insn, &func_id))
+			continue;
+
+		/* on kernels that don't yet support
+		 * bpf_probe_read_{kernel,user}[_str] helpers, fall back
+		 * to bpf_probe_read() which works well for old kernels
+		 */
+		switch (func_id) {
+		case BPF_FUNC_probe_read_kernel:
+		case BPF_FUNC_probe_read_user:
+			if (!kernel_supports(obj, FEAT_PROBE_READ_KERN))
+				insn->imm = BPF_FUNC_probe_read;
+			break;
+		case BPF_FUNC_probe_read_kernel_str:
+		case BPF_FUNC_probe_read_user_str:
+			if (!kernel_supports(obj, FEAT_PROBE_READ_KERN))
+				insn->imm = BPF_FUNC_probe_read_str;
+			break;
+		default:
+			break;
+		}
+	}
+	return 0;
+}
+
+static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attach_name,
+				     int *btf_obj_fd, int *btf_type_id);
+
+/* this is called as prog->sec_def->prog_prepare_load_fn for libbpf-supported sec_defs */
+static int libbpf_prepare_prog_load(struct bpf_program *prog,
+				    struct bpf_prog_load_opts *opts, long cookie)
+{
+	enum sec_def_flags def = cookie;
+
+	/* old kernels might not support specifying expected_attach_type */
+	if ((def & SEC_EXP_ATTACH_OPT) && !kernel_supports(prog->obj, FEAT_EXP_ATTACH_TYPE))
+		opts->expected_attach_type = 0;
+
+	if (def & SEC_SLEEPABLE)
+		opts->prog_flags |= BPF_F_SLEEPABLE;
+
+	if (prog->type == BPF_PROG_TYPE_XDP && (def & SEC_XDP_FRAGS))
+		opts->prog_flags |= BPF_F_XDP_HAS_FRAGS;
+
+	if ((def & SEC_ATTACH_BTF) && !prog->attach_btf_id) {
+		int btf_obj_fd = 0, btf_type_id = 0, err;
+		const char *attach_name;
+
+		attach_name = strchr(prog->sec_name, '/');
+		if (!attach_name) {
+			/* if BPF program is annotated with just SEC("fentry")
+			 * (or similar) without declaratively specifying
+			 * target, then it is expected that target will be
+			 * specified with bpf_program__set_attach_target() at
+			 * runtime before BPF object load step. If not, then
+			 * there is nothing to load into the kernel as BPF
+			 * verifier won't be able to validate BPF program
+			 * correctness anyways.
+			 */
+			pr_warn("prog '%s': no BTF-based attach target is specified, use bpf_program__set_attach_target()\n",
+				prog->name);
+			return -EINVAL;
+		}
+		attach_name++; /* skip over / */
+
+		err = libbpf_find_attach_btf_id(prog, attach_name, &btf_obj_fd, &btf_type_id);
+		if (err)
+			return err;
+
+		/* cache resolved BTF FD and BTF type ID in the prog */
+		prog->attach_btf_obj_fd = btf_obj_fd;
+		prog->attach_btf_id = btf_type_id;
+
+		/* but by now libbpf common logic is not utilizing
+		 * prog->atach_btf_obj_fd/prog->attach_btf_id anymore because
+		 * this callback is called after opts were populated by
+		 * libbpf, so this callback has to update opts explicitly here
+		 */
+		opts->attach_btf_obj_fd = btf_obj_fd;
+		opts->attach_btf_id = btf_type_id;
+	}
+	return 0;
+}
+
+static void fixup_verifier_log(struct bpf_program *prog, char *buf, size_t buf_sz);
+
+static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog,
+				struct bpf_insn *insns, int insns_cnt,
+				const char *license, __u32 kern_version, int *prog_fd)
+{
+	LIBBPF_OPTS(bpf_prog_load_opts, load_attr);
+	const char *prog_name = NULL;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	size_t log_buf_size = 0;
+	char *log_buf = NULL, *tmp;
+	int btf_fd, ret, err;
+	bool own_log_buf = true;
+	__u32 log_level = prog->log_level;
+
+	if (prog->type == BPF_PROG_TYPE_UNSPEC) {
+		/*
+		 * The program type must be set.  Most likely we couldn't find a proper
+		 * section definition at load time, and thus we didn't infer the type.
+		 */
+		pr_warn("prog '%s': missing BPF prog type, check ELF section name '%s'\n",
+			prog->name, prog->sec_name);
+		return -EINVAL;
+	}
+
+	if (!insns || !insns_cnt)
+		return -EINVAL;
+
+	load_attr.expected_attach_type = prog->expected_attach_type;
+	if (kernel_supports(obj, FEAT_PROG_NAME))
+		prog_name = prog->name;
+	load_attr.attach_prog_fd = prog->attach_prog_fd;
+	load_attr.attach_btf_obj_fd = prog->attach_btf_obj_fd;
+	load_attr.attach_btf_id = prog->attach_btf_id;
+	load_attr.kern_version = kern_version;
+	load_attr.prog_ifindex = prog->prog_ifindex;
+
+	/* specify func_info/line_info only if kernel supports them */
+	btf_fd = bpf_object__btf_fd(obj);
+	if (btf_fd >= 0 && kernel_supports(obj, FEAT_BTF_FUNC)) {
+		load_attr.prog_btf_fd = btf_fd;
+		load_attr.func_info = prog->func_info;
+		load_attr.func_info_rec_size = prog->func_info_rec_size;
+		load_attr.func_info_cnt = prog->func_info_cnt;
+		load_attr.line_info = prog->line_info;
+		load_attr.line_info_rec_size = prog->line_info_rec_size;
+		load_attr.line_info_cnt = prog->line_info_cnt;
+	}
+	load_attr.log_level = log_level;
+	load_attr.prog_flags = prog->prog_flags;
+	load_attr.fd_array = obj->fd_array;
+
+	/* adjust load_attr if sec_def provides custom preload callback */
+	if (prog->sec_def && prog->sec_def->prog_prepare_load_fn) {
+		err = prog->sec_def->prog_prepare_load_fn(prog, &load_attr, prog->sec_def->cookie);
+		if (err < 0) {
+			pr_warn("prog '%s': failed to prepare load attributes: %d\n",
+				prog->name, err);
+			return err;
+		}
+		insns = prog->insns;
+		insns_cnt = prog->insns_cnt;
+	}
+
+	if (obj->gen_loader) {
+		bpf_gen__prog_load(obj->gen_loader, prog->type, prog->name,
+				   license, insns, insns_cnt, &load_attr,
+				   prog - obj->programs);
+		*prog_fd = -1;
+		return 0;
+	}
+
+retry_load:
+	/* if log_level is zero, we don't request logs initially even if
+	 * custom log_buf is specified; if the program load fails, then we'll
+	 * bump log_level to 1 and use either custom log_buf or we'll allocate
+	 * our own and retry the load to get details on what failed
+	 */
+	if (log_level) {
+		if (prog->log_buf) {
+			log_buf = prog->log_buf;
+			log_buf_size = prog->log_size;
+			own_log_buf = false;
+		} else if (obj->log_buf) {
+			log_buf = obj->log_buf;
+			log_buf_size = obj->log_size;
+			own_log_buf = false;
+		} else {
+			log_buf_size = max((size_t)BPF_LOG_BUF_SIZE, log_buf_size * 2);
+			tmp = realloc(log_buf, log_buf_size);
+			if (!tmp) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			log_buf = tmp;
+			log_buf[0] = '\0';
+			own_log_buf = true;
+		}
+	}
+
+	load_attr.log_buf = log_buf;
+	load_attr.log_size = log_buf_size;
+	load_attr.log_level = log_level;
+
+	ret = bpf_prog_load(prog->type, prog_name, license, insns, insns_cnt, &load_attr);
+	if (ret >= 0) {
+		if (log_level && own_log_buf) {
+			pr_debug("prog '%s': -- BEGIN PROG LOAD LOG --\n%s-- END PROG LOAD LOG --\n",
+				 prog->name, log_buf);
+		}
+
+		if (obj->has_rodata && kernel_supports(obj, FEAT_PROG_BIND_MAP)) {
+			struct bpf_map *map;
+			int i;
+
+			for (i = 0; i < obj->nr_maps; i++) {
+				map = &prog->obj->maps[i];
+				if (map->libbpf_type != LIBBPF_MAP_RODATA)
+					continue;
+
+				if (bpf_prog_bind_map(ret, bpf_map__fd(map), NULL)) {
+					cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+					pr_warn("prog '%s': failed to bind map '%s': %s\n",
+						prog->name, map->real_name, cp);
+					/* Don't fail hard if can't bind rodata. */
+				}
+			}
+		}
+
+		*prog_fd = ret;
+		ret = 0;
+		goto out;
+	}
+
+	if (log_level == 0) {
+		log_level = 1;
+		goto retry_load;
+	}
+	/* On ENOSPC, increase log buffer size and retry, unless custom
+	 * log_buf is specified.
+	 * Be careful to not overflow u32, though. Kernel's log buf size limit
+	 * isn't part of UAPI so it can always be bumped to full 4GB. So don't
+	 * multiply by 2 unless we are sure we'll fit within 32 bits.
+	 * Currently, we'll get -EINVAL when we reach (UINT_MAX >> 2).
+	 */
+	if (own_log_buf && errno == ENOSPC && log_buf_size <= UINT_MAX / 2)
+		goto retry_load;
+
+	ret = -errno;
+
+	/* post-process verifier log to improve error descriptions */
+	fixup_verifier_log(prog, log_buf, log_buf_size);
+
+	cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+	pr_warn("prog '%s': BPF program load failed: %s\n", prog->name, cp);
+	pr_perm_msg(ret);
+
+	if (own_log_buf && log_buf && log_buf[0] != '\0') {
+		pr_warn("prog '%s': -- BEGIN PROG LOAD LOG --\n%s-- END PROG LOAD LOG --\n",
+			prog->name, log_buf);
+	}
+
+out:
+	if (own_log_buf)
+		free(log_buf);
+	return ret;
+}
+
+static char *find_prev_line(char *buf, char *cur)
+{
+	char *p;
+
+	if (cur == buf) /* end of a log buf */
+		return NULL;
+
+	p = cur - 1;
+	while (p - 1 >= buf && *(p - 1) != '\n')
+		p--;
+
+	return p;
+}
+
+static void patch_log(char *buf, size_t buf_sz, size_t log_sz,
+		      char *orig, size_t orig_sz, const char *patch)
+{
+	/* size of the remaining log content to the right from the to-be-replaced part */
+	size_t rem_sz = (buf + log_sz) - (orig + orig_sz);
+	size_t patch_sz = strlen(patch);
+
+	if (patch_sz != orig_sz) {
+		/* If patch line(s) are longer than original piece of verifier log,
+		 * shift log contents by (patch_sz - orig_sz) bytes to the right
+		 * starting from after to-be-replaced part of the log.
+		 *
+		 * If patch line(s) are shorter than original piece of verifier log,
+		 * shift log contents by (orig_sz - patch_sz) bytes to the left
+		 * starting from after to-be-replaced part of the log
+		 *
+		 * We need to be careful about not overflowing available
+		 * buf_sz capacity. If that's the case, we'll truncate the end
+		 * of the original log, as necessary.
+		 */
+		if (patch_sz > orig_sz) {
+			if (orig + patch_sz >= buf + buf_sz) {
+				/* patch is big enough to cover remaining space completely */
+				patch_sz -= (orig + patch_sz) - (buf + buf_sz) + 1;
+				rem_sz = 0;
+			} else if (patch_sz - orig_sz > buf_sz - log_sz) {
+				/* patch causes part of remaining log to be truncated */
+				rem_sz -= (patch_sz - orig_sz) - (buf_sz - log_sz);
+			}
+		}
+		/* shift remaining log to the right by calculated amount */
+		memmove(orig + patch_sz, orig + orig_sz, rem_sz);
+	}
+
+	memcpy(orig, patch, patch_sz);
+}
+
+static void fixup_log_failed_core_relo(struct bpf_program *prog,
+				       char *buf, size_t buf_sz, size_t log_sz,
+				       char *line1, char *line2, char *line3)
+{
+	/* Expected log for failed and not properly guarded CO-RE relocation:
+	 * line1 -> 123: (85) call unknown#195896080
+	 * line2 -> invalid func unknown#195896080
+	 * line3 -> <anything else or end of buffer>
+	 *
+	 * "123" is the index of the instruction that was poisoned. We extract
+	 * instruction index to find corresponding CO-RE relocation and
+	 * replace this part of the log with more relevant information about
+	 * failed CO-RE relocation.
+	 */
+	const struct bpf_core_relo *relo;
+	struct bpf_core_spec spec;
+	char patch[512], spec_buf[256];
+	int insn_idx, err, spec_len;
+
+	if (sscanf(line1, "%d: (%*d) call unknown#195896080\n", &insn_idx) != 1)
+		return;
+
+	relo = find_relo_core(prog, insn_idx);
+	if (!relo)
+		return;
+
+	err = bpf_core_parse_spec(prog->name, prog->obj->btf, relo, &spec);
+	if (err)
+		return;
+
+	spec_len = bpf_core_format_spec(spec_buf, sizeof(spec_buf), &spec);
+	snprintf(patch, sizeof(patch),
+		 "%d: <invalid CO-RE relocation>\n"
+		 "failed to resolve CO-RE relocation %s%s\n",
+		 insn_idx, spec_buf, spec_len >= sizeof(spec_buf) ? "..." : "");
+
+	patch_log(buf, buf_sz, log_sz, line1, line3 - line1, patch);
+}
+
+static void fixup_log_missing_map_load(struct bpf_program *prog,
+				       char *buf, size_t buf_sz, size_t log_sz,
+				       char *line1, char *line2, char *line3)
+{
+	/* Expected log for failed and not properly guarded CO-RE relocation:
+	 * line1 -> 123: (85) call unknown#2001000345
+	 * line2 -> invalid func unknown#2001000345
+	 * line3 -> <anything else or end of buffer>
+	 *
+	 * "123" is the index of the instruction that was poisoned.
+	 * "345" in "2001000345" are map index in obj->maps to fetch map name.
+	 */
+	struct bpf_object *obj = prog->obj;
+	const struct bpf_map *map;
+	int insn_idx, map_idx;
+	char patch[128];
+
+	if (sscanf(line1, "%d: (%*d) call unknown#%d\n", &insn_idx, &map_idx) != 2)
+		return;
+
+	map_idx -= MAP_LDIMM64_POISON_BASE;
+	if (map_idx < 0 || map_idx >= obj->nr_maps)
+		return;
+	map = &obj->maps[map_idx];
+
+	snprintf(patch, sizeof(patch),
+		 "%d: <invalid BPF map reference>\n"
+		 "BPF map '%s' is referenced but wasn't created\n",
+		 insn_idx, map->name);
+
+	patch_log(buf, buf_sz, log_sz, line1, line3 - line1, patch);
+}
+
+static void fixup_verifier_log(struct bpf_program *prog, char *buf, size_t buf_sz)
+{
+	/* look for familiar error patterns in last N lines of the log */
+	const size_t max_last_line_cnt = 10;
+	char *prev_line, *cur_line, *next_line;
+	size_t log_sz;
+	int i;
+
+	if (!buf)
+		return;
+
+	log_sz = strlen(buf) + 1;
+	next_line = buf + log_sz - 1;
+
+	for (i = 0; i < max_last_line_cnt; i++, next_line = cur_line) {
+		cur_line = find_prev_line(buf, next_line);
+		if (!cur_line)
+			return;
+
+		/* failed CO-RE relocation case */
+		if (str_has_pfx(cur_line, "invalid func unknown#195896080\n")) {
+			prev_line = find_prev_line(buf, cur_line);
+			if (!prev_line)
+				continue;
+
+			fixup_log_failed_core_relo(prog, buf, buf_sz, log_sz,
+						   prev_line, cur_line, next_line);
+			return;
+		} else if (str_has_pfx(cur_line, "invalid func unknown#"MAP_LDIMM64_POISON_PFX)) {
+			prev_line = find_prev_line(buf, cur_line);
+			if (!prev_line)
+				continue;
+
+			fixup_log_missing_map_load(prog, buf, buf_sz, log_sz,
+						   prev_line, cur_line, next_line);
+			return;
+		}
+	}
+}
+
+static int bpf_program_record_relos(struct bpf_program *prog)
+{
+	struct bpf_object *obj = prog->obj;
+	int i;
+
+	for (i = 0; i < prog->nr_reloc; i++) {
+		struct reloc_desc *relo = &prog->reloc_desc[i];
+		struct extern_desc *ext = &obj->externs[relo->sym_off];
+
+		switch (relo->type) {
+		case RELO_EXTERN_VAR:
+			if (ext->type != EXT_KSYM)
+				continue;
+			bpf_gen__record_extern(obj->gen_loader, ext->name,
+					       ext->is_weak, !ext->ksym.type_id,
+					       BTF_KIND_VAR, relo->insn_idx);
+			break;
+		case RELO_EXTERN_FUNC:
+			bpf_gen__record_extern(obj->gen_loader, ext->name,
+					       ext->is_weak, false, BTF_KIND_FUNC,
+					       relo->insn_idx);
+			break;
+		case RELO_CORE: {
+			struct bpf_core_relo cr = {
+				.insn_off = relo->insn_idx * 8,
+				.type_id = relo->core_relo->type_id,
+				.access_str_off = relo->core_relo->access_str_off,
+				.kind = relo->core_relo->kind,
+			};
+
+			bpf_gen__record_relo_core(obj->gen_loader, &cr);
+			break;
+		}
+		default:
+			continue;
+		}
+	}
+	return 0;
+}
+
+static int
+bpf_object__load_progs(struct bpf_object *obj, int log_level)
+{
+	struct bpf_program *prog;
+	size_t i;
+	int err;
+
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		err = bpf_object__sanitize_prog(obj, prog);
+		if (err)
+			return err;
+	}
+
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		if (prog_is_subprog(obj, prog))
+			continue;
+		if (!prog->autoload) {
+			pr_debug("prog '%s': skipped loading\n", prog->name);
+			continue;
+		}
+		prog->log_level |= log_level;
+
+		if (obj->gen_loader)
+			bpf_program_record_relos(prog);
+
+		err = bpf_object_load_prog(obj, prog, prog->insns, prog->insns_cnt,
+					   obj->license, obj->kern_version, &prog->fd);
+		if (err) {
+			pr_warn("prog '%s': failed to load: %d\n", prog->name, err);
+			return err;
+		}
+	}
+
+	bpf_object__free_relocs(obj);
+	return 0;
+}
+
+static const struct bpf_sec_def *find_sec_def(const char *sec_name);
+
+static int bpf_object_init_progs(struct bpf_object *obj, const struct bpf_object_open_opts *opts)
+{
+	struct bpf_program *prog;
+	int err;
+
+	bpf_object__for_each_program(prog, obj) {
+		prog->sec_def = find_sec_def(prog->sec_name);
+		if (!prog->sec_def) {
+			/* couldn't guess, but user might manually specify */
+			pr_debug("prog '%s': unrecognized ELF section name '%s'\n",
+				prog->name, prog->sec_name);
+			continue;
+		}
+
+		prog->type = prog->sec_def->prog_type;
+		prog->expected_attach_type = prog->sec_def->expected_attach_type;
+
+		/* sec_def can have custom callback which should be called
+		 * after bpf_program is initialized to adjust its properties
+		 */
+		if (prog->sec_def->prog_setup_fn) {
+			err = prog->sec_def->prog_setup_fn(prog, prog->sec_def->cookie);
+			if (err < 0) {
+				pr_warn("prog '%s': failed to initialize: %d\n",
+					prog->name, err);
+				return err;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static struct bpf_object *bpf_object_open(const char *path, const void *obj_buf, size_t obj_buf_sz,
+					  const struct bpf_object_open_opts *opts)
+{
+	const char *obj_name, *kconfig, *btf_tmp_path;
+	struct bpf_object *obj;
+	char tmp_name[64];
+	int err;
+	char *log_buf;
+	size_t log_size;
+	__u32 log_level;
+
+	if (elf_version(EV_CURRENT) == EV_NONE) {
+		pr_warn("failed to init libelf for %s\n",
+			path ? : "(mem buf)");
+		return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
+	}
+
+	if (!OPTS_VALID(opts, bpf_object_open_opts))
+		return ERR_PTR(-EINVAL);
+
+	obj_name = OPTS_GET(opts, object_name, NULL);
+	if (obj_buf) {
+		if (!obj_name) {
+			snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
+				 (unsigned long)obj_buf,
+				 (unsigned long)obj_buf_sz);
+			obj_name = tmp_name;
+		}
+		path = obj_name;
+		pr_debug("loading object '%s' from buffer\n", obj_name);
+	}
+
+	log_buf = OPTS_GET(opts, kernel_log_buf, NULL);
+	log_size = OPTS_GET(opts, kernel_log_size, 0);
+	log_level = OPTS_GET(opts, kernel_log_level, 0);
+	if (log_size > UINT_MAX)
+		return ERR_PTR(-EINVAL);
+	if (log_size && !log_buf)
+		return ERR_PTR(-EINVAL);
+
+	obj = bpf_object__new(path, obj_buf, obj_buf_sz, obj_name);
+	if (IS_ERR(obj))
+		return obj;
+
+	obj->log_buf = log_buf;
+	obj->log_size = log_size;
+	obj->log_level = log_level;
+
+	btf_tmp_path = OPTS_GET(opts, btf_custom_path, NULL);
+	if (btf_tmp_path) {
+		if (strlen(btf_tmp_path) >= PATH_MAX) {
+			err = -ENAMETOOLONG;
+			goto out;
+		}
+		obj->btf_custom_path = strdup(btf_tmp_path);
+		if (!obj->btf_custom_path) {
+			err = -ENOMEM;
+			goto out;
+		}
+	}
+
+	kconfig = OPTS_GET(opts, kconfig, NULL);
+	if (kconfig) {
+		obj->kconfig = strdup(kconfig);
+		if (!obj->kconfig) {
+			err = -ENOMEM;
+			goto out;
+		}
+	}
+
+	err = bpf_object__elf_init(obj);
+	err = err ? : bpf_object__check_endianness(obj);
+	err = err ? : bpf_object__elf_collect(obj);
+	err = err ? : bpf_object__collect_externs(obj);
+	err = err ? : bpf_object_fixup_btf(obj);
+	err = err ? : bpf_object__init_maps(obj, opts);
+	err = err ? : bpf_object_init_progs(obj, opts);
+	err = err ? : bpf_object__collect_relos(obj);
+	if (err)
+		goto out;
+
+	bpf_object__elf_finish(obj);
+
+	return obj;
+out:
+	bpf_object__close(obj);
+	return ERR_PTR(err);
+}
+
+struct bpf_object *
+bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts)
+{
+	if (!path)
+		return libbpf_err_ptr(-EINVAL);
+
+	pr_debug("loading %s\n", path);
+
+	return libbpf_ptr(bpf_object_open(path, NULL, 0, opts));
+}
+
+struct bpf_object *bpf_object__open(const char *path)
+{
+	return bpf_object__open_file(path, NULL);
+}
+
+struct bpf_object *
+bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
+		     const struct bpf_object_open_opts *opts)
+{
+	if (!obj_buf || obj_buf_sz == 0)
+		return libbpf_err_ptr(-EINVAL);
+
+	return libbpf_ptr(bpf_object_open(NULL, obj_buf, obj_buf_sz, opts));
+}
+
+static int bpf_object_unload(struct bpf_object *obj)
+{
+	size_t i;
+
+	if (!obj)
+		return libbpf_err(-EINVAL);
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		zclose(obj->maps[i].fd);
+		if (obj->maps[i].st_ops)
+			zfree(&obj->maps[i].st_ops->kern_vdata);
+	}
+
+	for (i = 0; i < obj->nr_programs; i++)
+		bpf_program__unload(&obj->programs[i]);
+
+	return 0;
+}
+
+static int bpf_object__sanitize_maps(struct bpf_object *obj)
+{
+	struct bpf_map *m;
+
+	bpf_object__for_each_map(m, obj) {
+		if (!bpf_map__is_internal(m))
+			continue;
+		if (!kernel_supports(obj, FEAT_ARRAY_MMAP))
+			m->def.map_flags ^= BPF_F_MMAPABLE;
+	}
+
+	return 0;
+}
+
+int libbpf_kallsyms_parse(kallsyms_cb_t cb, void *ctx)
+{
+	char sym_type, sym_name[500];
+	unsigned long long sym_addr;
+	int ret, err = 0;
+	FILE *f;
+
+	f = fopen("/proc/kallsyms", "r");
+	if (!f) {
+		err = -errno;
+		pr_warn("failed to open /proc/kallsyms: %d\n", err);
+		return err;
+	}
+
+	while (true) {
+		ret = fscanf(f, "%llx %c %499s%*[^\n]\n",
+			     &sym_addr, &sym_type, sym_name);
+		if (ret == EOF && feof(f))
+			break;
+		if (ret != 3) {
+			pr_warn("failed to read kallsyms entry: %d\n", ret);
+			err = -EINVAL;
+			break;
+		}
+
+		err = cb(sym_addr, sym_type, sym_name, ctx);
+		if (err)
+			break;
+	}
+
+	fclose(f);
+	return err;
+}
+
+static int kallsyms_cb(unsigned long long sym_addr, char sym_type,
+		       const char *sym_name, void *ctx)
+{
+	struct bpf_object *obj = ctx;
+	const struct btf_type *t;
+	struct extern_desc *ext;
+
+	ext = find_extern_by_name(obj, sym_name);
+	if (!ext || ext->type != EXT_KSYM)
+		return 0;
+
+	t = btf__type_by_id(obj->btf, ext->btf_id);
+	if (!btf_is_var(t))
+		return 0;
+
+	if (ext->is_set && ext->ksym.addr != sym_addr) {
+		pr_warn("extern (ksym) '%s': resolution is ambiguous: 0x%llx or 0x%llx\n",
+			sym_name, ext->ksym.addr, sym_addr);
+		return -EINVAL;
+	}
+	if (!ext->is_set) {
+		ext->is_set = true;
+		ext->ksym.addr = sym_addr;
+		pr_debug("extern (ksym) '%s': set to 0x%llx\n", sym_name, sym_addr);
+	}
+	return 0;
+}
+
+static int bpf_object__read_kallsyms_file(struct bpf_object *obj)
+{
+	return libbpf_kallsyms_parse(kallsyms_cb, obj);
+}
+
+static int find_ksym_btf_id(struct bpf_object *obj, const char *ksym_name,
+			    __u16 kind, struct btf **res_btf,
+			    struct module_btf **res_mod_btf)
+{
+	struct module_btf *mod_btf;
+	struct btf *btf;
+	int i, id, err;
+
+	btf = obj->btf_vmlinux;
+	mod_btf = NULL;
+	id = btf__find_by_name_kind(btf, ksym_name, kind);
+
+	if (id == -ENOENT) {
+		err = load_module_btfs(obj);
+		if (err)
+			return err;
+
+		for (i = 0; i < obj->btf_module_cnt; i++) {
+			/* we assume module_btf's BTF FD is always >0 */
+			mod_btf = &obj->btf_modules[i];
+			btf = mod_btf->btf;
+			id = btf__find_by_name_kind_own(btf, ksym_name, kind);
+			if (id != -ENOENT)
+				break;
+		}
+	}
+	if (id <= 0)
+		return -ESRCH;
+
+	*res_btf = btf;
+	*res_mod_btf = mod_btf;
+	return id;
+}
+
+static int bpf_object__resolve_ksym_var_btf_id(struct bpf_object *obj,
+					       struct extern_desc *ext)
+{
+	const struct btf_type *targ_var, *targ_type;
+	__u32 targ_type_id, local_type_id;
+	struct module_btf *mod_btf = NULL;
+	const char *targ_var_name;
+	struct btf *btf = NULL;
+	int id, err;
+
+	id = find_ksym_btf_id(obj, ext->name, BTF_KIND_VAR, &btf, &mod_btf);
+	if (id < 0) {
+		if (id == -ESRCH && ext->is_weak)
+			return 0;
+		pr_warn("extern (var ksym) '%s': not found in kernel BTF\n",
+			ext->name);
+		return id;
+	}
+
+	/* find local type_id */
+	local_type_id = ext->ksym.type_id;
+
+	/* find target type_id */
+	targ_var = btf__type_by_id(btf, id);
+	targ_var_name = btf__name_by_offset(btf, targ_var->name_off);
+	targ_type = skip_mods_and_typedefs(btf, targ_var->type, &targ_type_id);
+
+	err = bpf_core_types_are_compat(obj->btf, local_type_id,
+					btf, targ_type_id);
+	if (err <= 0) {
+		const struct btf_type *local_type;
+		const char *targ_name, *local_name;
+
+		local_type = btf__type_by_id(obj->btf, local_type_id);
+		local_name = btf__name_by_offset(obj->btf, local_type->name_off);
+		targ_name = btf__name_by_offset(btf, targ_type->name_off);
+
+		pr_warn("extern (var ksym) '%s': incompatible types, expected [%d] %s %s, but kernel has [%d] %s %s\n",
+			ext->name, local_type_id,
+			btf_kind_str(local_type), local_name, targ_type_id,
+			btf_kind_str(targ_type), targ_name);
+		return -EINVAL;
+	}
+
+	ext->is_set = true;
+	ext->ksym.kernel_btf_obj_fd = mod_btf ? mod_btf->fd : 0;
+	ext->ksym.kernel_btf_id = id;
+	pr_debug("extern (var ksym) '%s': resolved to [%d] %s %s\n",
+		 ext->name, id, btf_kind_str(targ_var), targ_var_name);
+
+	return 0;
+}
+
+static int bpf_object__resolve_ksym_func_btf_id(struct bpf_object *obj,
+						struct extern_desc *ext)
+{
+	int local_func_proto_id, kfunc_proto_id, kfunc_id;
+	struct module_btf *mod_btf = NULL;
+	const struct btf_type *kern_func;
+	struct btf *kern_btf = NULL;
+	int ret;
+
+	local_func_proto_id = ext->ksym.type_id;
+
+	kfunc_id = find_ksym_btf_id(obj, ext->name, BTF_KIND_FUNC, &kern_btf, &mod_btf);
+	if (kfunc_id < 0) {
+		if (kfunc_id == -ESRCH && ext->is_weak)
+			return 0;
+		pr_warn("extern (func ksym) '%s': not found in kernel or module BTFs\n",
+			ext->name);
+		return kfunc_id;
+	}
+
+	kern_func = btf__type_by_id(kern_btf, kfunc_id);
+	kfunc_proto_id = kern_func->type;
+
+	ret = bpf_core_types_are_compat(obj->btf, local_func_proto_id,
+					kern_btf, kfunc_proto_id);
+	if (ret <= 0) {
+		pr_warn("extern (func ksym) '%s': func_proto [%d] incompatible with kernel [%d]\n",
+			ext->name, local_func_proto_id, kfunc_proto_id);
+		return -EINVAL;
+	}
+
+	/* set index for module BTF fd in fd_array, if unset */
+	if (mod_btf && !mod_btf->fd_array_idx) {
+		/* insn->off is s16 */
+		if (obj->fd_array_cnt == INT16_MAX) {
+			pr_warn("extern (func ksym) '%s': module BTF fd index %d too big to fit in bpf_insn offset\n",
+				ext->name, mod_btf->fd_array_idx);
+			return -E2BIG;
+		}
+		/* Cannot use index 0 for module BTF fd */
+		if (!obj->fd_array_cnt)
+			obj->fd_array_cnt = 1;
+
+		ret = libbpf_ensure_mem((void **)&obj->fd_array, &obj->fd_array_cap, sizeof(int),
+					obj->fd_array_cnt + 1);
+		if (ret)
+			return ret;
+		mod_btf->fd_array_idx = obj->fd_array_cnt;
+		/* we assume module BTF FD is always >0 */
+		obj->fd_array[obj->fd_array_cnt++] = mod_btf->fd;
+	}
+
+	ext->is_set = true;
+	ext->ksym.kernel_btf_id = kfunc_id;
+	ext->ksym.btf_fd_idx = mod_btf ? mod_btf->fd_array_idx : 0;
+	pr_debug("extern (func ksym) '%s': resolved to kernel [%d]\n",
+		 ext->name, kfunc_id);
+
+	return 0;
+}
+
+static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj)
+{
+	const struct btf_type *t;
+	struct extern_desc *ext;
+	int i, err;
+
+	for (i = 0; i < obj->nr_extern; i++) {
+		ext = &obj->externs[i];
+		if (ext->type != EXT_KSYM || !ext->ksym.type_id)
+			continue;
+
+		if (obj->gen_loader) {
+			ext->is_set = true;
+			ext->ksym.kernel_btf_obj_fd = 0;
+			ext->ksym.kernel_btf_id = 0;
+			continue;
+		}
+		t = btf__type_by_id(obj->btf, ext->btf_id);
+		if (btf_is_var(t))
+			err = bpf_object__resolve_ksym_var_btf_id(obj, ext);
+		else
+			err = bpf_object__resolve_ksym_func_btf_id(obj, ext);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int bpf_object__resolve_externs(struct bpf_object *obj,
+				       const char *extra_kconfig)
+{
+	bool need_config = false, need_kallsyms = false;
+	bool need_vmlinux_btf = false;
+	struct extern_desc *ext;
+	void *kcfg_data = NULL;
+	int err, i;
+
+	if (obj->nr_extern == 0)
+		return 0;
+
+	if (obj->kconfig_map_idx >= 0)
+		kcfg_data = obj->maps[obj->kconfig_map_idx].mmaped;
+
+	for (i = 0; i < obj->nr_extern; i++) {
+		ext = &obj->externs[i];
+
+		if (ext->type == EXT_KSYM) {
+			if (ext->ksym.type_id)
+				need_vmlinux_btf = true;
+			else
+				need_kallsyms = true;
+			continue;
+		} else if (ext->type == EXT_KCFG) {
+			void *ext_ptr = kcfg_data + ext->kcfg.data_off;
+			__u64 value = 0;
+
+			/* Kconfig externs need actual /proc/config.gz */
+			if (str_has_pfx(ext->name, "CONFIG_")) {
+				need_config = true;
+				continue;
+			}
+
+			/* Virtual kcfg externs are customly handled by libbpf */
+			if (strcmp(ext->name, "LINUX_KERNEL_VERSION") == 0) {
+				value = get_kernel_version();
+				if (!value) {
+					pr_warn("extern (kcfg) '%s': failed to get kernel version\n", ext->name);
+					return -EINVAL;
+				}
+			} else if (strcmp(ext->name, "LINUX_HAS_BPF_COOKIE") == 0) {
+				value = kernel_supports(obj, FEAT_BPF_COOKIE);
+			} else if (strcmp(ext->name, "LINUX_HAS_SYSCALL_WRAPPER") == 0) {
+				value = kernel_supports(obj, FEAT_SYSCALL_WRAPPER);
+			} else if (!str_has_pfx(ext->name, "LINUX_") || !ext->is_weak) {
+				/* Currently libbpf supports only CONFIG_ and LINUX_ prefixed
+				 * __kconfig externs, where LINUX_ ones are virtual and filled out
+				 * customly by libbpf (their values don't come from Kconfig).
+				 * If LINUX_xxx variable is not recognized by libbpf, but is marked
+				 * __weak, it defaults to zero value, just like for CONFIG_xxx
+				 * externs.
+				 */
+				pr_warn("extern (kcfg) '%s': unrecognized virtual extern\n", ext->name);
+				return -EINVAL;
+			}
+
+			err = set_kcfg_value_num(ext, ext_ptr, value);
+			if (err)
+				return err;
+			pr_debug("extern (kcfg) '%s': set to 0x%llx\n",
+				 ext->name, (long long)value);
+		} else {
+			pr_warn("extern '%s': unrecognized extern kind\n", ext->name);
+			return -EINVAL;
+		}
+	}
+	if (need_config && extra_kconfig) {
+		err = bpf_object__read_kconfig_mem(obj, extra_kconfig, kcfg_data);
+		if (err)
+			return -EINVAL;
+		need_config = false;
+		for (i = 0; i < obj->nr_extern; i++) {
+			ext = &obj->externs[i];
+			if (ext->type == EXT_KCFG && !ext->is_set) {
+				need_config = true;
+				break;
+			}
+		}
+	}
+	if (need_config) {
+		err = bpf_object__read_kconfig_file(obj, kcfg_data);
+		if (err)
+			return -EINVAL;
+	}
+	if (need_kallsyms) {
+		err = bpf_object__read_kallsyms_file(obj);
+		if (err)
+			return -EINVAL;
+	}
+	if (need_vmlinux_btf) {
+		err = bpf_object__resolve_ksyms_btf_id(obj);
+		if (err)
+			return -EINVAL;
+	}
+	for (i = 0; i < obj->nr_extern; i++) {
+		ext = &obj->externs[i];
+
+		if (!ext->is_set && !ext->is_weak) {
+			pr_warn("extern '%s' (strong): not resolved\n", ext->name);
+			return -ESRCH;
+		} else if (!ext->is_set) {
+			pr_debug("extern '%s' (weak): not resolved, defaulting to zero\n",
+				 ext->name);
+		}
+	}
+
+	return 0;
+}
+
+static int bpf_object_load(struct bpf_object *obj, int extra_log_level, const char *target_btf_path)
+{
+	int err, i;
+
+	if (!obj)
+		return libbpf_err(-EINVAL);
+
+	if (obj->loaded) {
+		pr_warn("object '%s': load can't be attempted twice\n", obj->name);
+		return libbpf_err(-EINVAL);
+	}
+
+	if (obj->gen_loader)
+		bpf_gen__init(obj->gen_loader, extra_log_level, obj->nr_programs, obj->nr_maps);
+
+	err = bpf_object__probe_loading(obj);
+	err = err ? : bpf_object__load_vmlinux_btf(obj, false);
+	err = err ? : bpf_object__resolve_externs(obj, obj->kconfig);
+	err = err ? : bpf_object__sanitize_and_load_btf(obj);
+	err = err ? : bpf_object__sanitize_maps(obj);
+	err = err ? : bpf_object__init_kern_struct_ops_maps(obj);
+	err = err ? : bpf_object__create_maps(obj);
+	err = err ? : bpf_object__relocate(obj, obj->btf_custom_path ? : target_btf_path);
+	err = err ? : bpf_object__load_progs(obj, extra_log_level);
+	err = err ? : bpf_object_init_prog_arrays(obj);
+
+	if (obj->gen_loader) {
+		/* reset FDs */
+		if (obj->btf)
+			btf__set_fd(obj->btf, -1);
+		for (i = 0; i < obj->nr_maps; i++)
+			obj->maps[i].fd = -1;
+		if (!err)
+			err = bpf_gen__finish(obj->gen_loader, obj->nr_programs, obj->nr_maps);
+	}
+
+	/* clean up fd_array */
+	zfree(&obj->fd_array);
+
+	/* clean up module BTFs */
+	for (i = 0; i < obj->btf_module_cnt; i++) {
+		close(obj->btf_modules[i].fd);
+		btf__free(obj->btf_modules[i].btf);
+		free(obj->btf_modules[i].name);
+	}
+	free(obj->btf_modules);
+
+	/* clean up vmlinux BTF */
+	btf__free(obj->btf_vmlinux);
+	obj->btf_vmlinux = NULL;
+
+	obj->loaded = true; /* doesn't matter if successfully or not */
+
+	if (err)
+		goto out;
+
+	return 0;
+out:
+	/* unpin any maps that were auto-pinned during load */
+	for (i = 0; i < obj->nr_maps; i++)
+		if (obj->maps[i].pinned && !obj->maps[i].reused)
+			bpf_map__unpin(&obj->maps[i], NULL);
+
+	bpf_object_unload(obj);
+	pr_warn("failed to load object '%s'\n", obj->path);
+	return libbpf_err(err);
+}
+
+int bpf_object__load(struct bpf_object *obj)
+{
+	return bpf_object_load(obj, 0, NULL);
+}
+
+static int make_parent_dir(const char *path)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	char *dname, *dir;
+	int err = 0;
+
+	dname = strdup(path);
+	if (dname == NULL)
+		return -ENOMEM;
+
+	dir = dirname(dname);
+	if (mkdir(dir, 0700) && errno != EEXIST)
+		err = -errno;
+
+	free(dname);
+	if (err) {
+		cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
+		pr_warn("failed to mkdir %s: %s\n", path, cp);
+	}
+	return err;
+}
+
+static int check_path(const char *path)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct statfs st_fs;
+	char *dname, *dir;
+	int err = 0;
+
+	if (path == NULL)
+		return -EINVAL;
+
+	dname = strdup(path);
+	if (dname == NULL)
+		return -ENOMEM;
+
+	dir = dirname(dname);
+	if (statfs(dir, &st_fs)) {
+		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+		pr_warn("failed to statfs %s: %s\n", dir, cp);
+		err = -errno;
+	}
+	free(dname);
+
+	if (!err && st_fs.f_type != BPF_FS_MAGIC) {
+		pr_warn("specified path %s is not on BPF FS\n", path);
+		err = -EINVAL;
+	}
+
+	return err;
+}
+
+int bpf_program__pin(struct bpf_program *prog, const char *path)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err;
+
+	if (prog->fd < 0) {
+		pr_warn("prog '%s': can't pin program that wasn't loaded\n", prog->name);
+		return libbpf_err(-EINVAL);
+	}
+
+	err = make_parent_dir(path);
+	if (err)
+		return libbpf_err(err);
+
+	err = check_path(path);
+	if (err)
+		return libbpf_err(err);
+
+	if (bpf_obj_pin(prog->fd, path)) {
+		err = -errno;
+		cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+		pr_warn("prog '%s': failed to pin at '%s': %s\n", prog->name, path, cp);
+		return libbpf_err(err);
+	}
+
+	pr_debug("prog '%s': pinned at '%s'\n", prog->name, path);
+	return 0;
+}
+
+int bpf_program__unpin(struct bpf_program *prog, const char *path)
+{
+	int err;
+
+	if (prog->fd < 0) {
+		pr_warn("prog '%s': can't unpin program that wasn't loaded\n", prog->name);
+		return libbpf_err(-EINVAL);
+	}
+
+	err = check_path(path);
+	if (err)
+		return libbpf_err(err);
+
+	err = unlink(path);
+	if (err)
+		return libbpf_err(-errno);
+
+	pr_debug("prog '%s': unpinned from '%s'\n", prog->name, path);
+	return 0;
+}
+
+int bpf_map__pin(struct bpf_map *map, const char *path)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err;
+
+	if (map == NULL) {
+		pr_warn("invalid map pointer\n");
+		return libbpf_err(-EINVAL);
+	}
+
+	if (map->pin_path) {
+		if (path && strcmp(path, map->pin_path)) {
+			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
+				bpf_map__name(map), map->pin_path, path);
+			return libbpf_err(-EINVAL);
+		} else if (map->pinned) {
+			pr_debug("map '%s' already pinned at '%s'; not re-pinning\n",
+				 bpf_map__name(map), map->pin_path);
+			return 0;
+		}
+	} else {
+		if (!path) {
+			pr_warn("missing a path to pin map '%s' at\n",
+				bpf_map__name(map));
+			return libbpf_err(-EINVAL);
+		} else if (map->pinned) {
+			pr_warn("map '%s' already pinned\n", bpf_map__name(map));
+			return libbpf_err(-EEXIST);
+		}
+
+		map->pin_path = strdup(path);
+		if (!map->pin_path) {
+			err = -errno;
+			goto out_err;
+		}
+	}
+
+	err = make_parent_dir(map->pin_path);
+	if (err)
+		return libbpf_err(err);
+
+	err = check_path(map->pin_path);
+	if (err)
+		return libbpf_err(err);
+
+	if (bpf_obj_pin(map->fd, map->pin_path)) {
+		err = -errno;
+		goto out_err;
+	}
+
+	map->pinned = true;
+	pr_debug("pinned map '%s'\n", map->pin_path);
+
+	return 0;
+
+out_err:
+	cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
+	pr_warn("failed to pin map: %s\n", cp);
+	return libbpf_err(err);
+}
+
+int bpf_map__unpin(struct bpf_map *map, const char *path)
+{
+	int err;
+
+	if (map == NULL) {
+		pr_warn("invalid map pointer\n");
+		return libbpf_err(-EINVAL);
+	}
+
+	if (map->pin_path) {
+		if (path && strcmp(path, map->pin_path)) {
+			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
+				bpf_map__name(map), map->pin_path, path);
+			return libbpf_err(-EINVAL);
+		}
+		path = map->pin_path;
+	} else if (!path) {
+		pr_warn("no path to unpin map '%s' from\n",
+			bpf_map__name(map));
+		return libbpf_err(-EINVAL);
+	}
+
+	err = check_path(path);
+	if (err)
+		return libbpf_err(err);
+
+	err = unlink(path);
+	if (err != 0)
+		return libbpf_err(-errno);
+
+	map->pinned = false;
+	pr_debug("unpinned map '%s' from '%s'\n", bpf_map__name(map), path);
+
+	return 0;
+}
+
+int bpf_map__set_pin_path(struct bpf_map *map, const char *path)
+{
+	char *new = NULL;
+
+	if (path) {
+		new = strdup(path);
+		if (!new)
+			return libbpf_err(-errno);
+	}
+
+	free(map->pin_path);
+	map->pin_path = new;
+	return 0;
+}
+
+__alias(bpf_map__pin_path)
+const char *bpf_map__get_pin_path(const struct bpf_map *map);
+
+const char *bpf_map__pin_path(const struct bpf_map *map)
+{
+	return map->pin_path;
+}
+
+bool bpf_map__is_pinned(const struct bpf_map *map)
+{
+	return map->pinned;
+}
+
+static void sanitize_pin_path(char *s)
+{
+	/* bpffs disallows periods in path names */
+	while (*s) {
+		if (*s == '.')
+			*s = '_';
+		s++;
+	}
+}
+
+int bpf_object__pin_maps(struct bpf_object *obj, const char *path)
+{
+	struct bpf_map *map;
+	int err;
+
+	if (!obj)
+		return libbpf_err(-ENOENT);
+
+	if (!obj->loaded) {
+		pr_warn("object not yet loaded; load it first\n");
+		return libbpf_err(-ENOENT);
+	}
+
+	bpf_object__for_each_map(map, obj) {
+		char *pin_path = NULL;
+		char buf[PATH_MAX];
+
+		if (!map->autocreate)
+			continue;
+
+		if (path) {
+			err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
+			if (err)
+				goto err_unpin_maps;
+			sanitize_pin_path(buf);
+			pin_path = buf;
+		} else if (!map->pin_path) {
+			continue;
+		}
+
+		err = bpf_map__pin(map, pin_path);
+		if (err)
+			goto err_unpin_maps;
+	}
+
+	return 0;
+
+err_unpin_maps:
+	while ((map = bpf_object__prev_map(obj, map))) {
+		if (!map->pin_path)
+			continue;
+
+		bpf_map__unpin(map, NULL);
+	}
+
+	return libbpf_err(err);
+}
+
+int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
+{
+	struct bpf_map *map;
+	int err;
+
+	if (!obj)
+		return libbpf_err(-ENOENT);
+
+	bpf_object__for_each_map(map, obj) {
+		char *pin_path = NULL;
+		char buf[PATH_MAX];
+
+		if (path) {
+			err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
+			if (err)
+				return libbpf_err(err);
+			sanitize_pin_path(buf);
+			pin_path = buf;
+		} else if (!map->pin_path) {
+			continue;
+		}
+
+		err = bpf_map__unpin(map, pin_path);
+		if (err)
+			return libbpf_err(err);
+	}
+
+	return 0;
+}
+
+int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
+{
+	struct bpf_program *prog;
+	char buf[PATH_MAX];
+	int err;
+
+	if (!obj)
+		return libbpf_err(-ENOENT);
+
+	if (!obj->loaded) {
+		pr_warn("object not yet loaded; load it first\n");
+		return libbpf_err(-ENOENT);
+	}
+
+	bpf_object__for_each_program(prog, obj) {
+		err = pathname_concat(buf, sizeof(buf), path, prog->name);
+		if (err)
+			goto err_unpin_programs;
+
+		err = bpf_program__pin(prog, buf);
+		if (err)
+			goto err_unpin_programs;
+	}
+
+	return 0;
+
+err_unpin_programs:
+	while ((prog = bpf_object__prev_program(obj, prog))) {
+		if (pathname_concat(buf, sizeof(buf), path, prog->name))
+			continue;
+
+		bpf_program__unpin(prog, buf);
+	}
+
+	return libbpf_err(err);
+}
+
+int bpf_object__unpin_programs(struct bpf_object *obj, const char *path)
+{
+	struct bpf_program *prog;
+	int err;
+
+	if (!obj)
+		return libbpf_err(-ENOENT);
+
+	bpf_object__for_each_program(prog, obj) {
+		char buf[PATH_MAX];
+
+		err = pathname_concat(buf, sizeof(buf), path, prog->name);
+		if (err)
+			return libbpf_err(err);
+
+		err = bpf_program__unpin(prog, buf);
+		if (err)
+			return libbpf_err(err);
+	}
+
+	return 0;
+}
+
+int bpf_object__pin(struct bpf_object *obj, const char *path)
+{
+	int err;
+
+	err = bpf_object__pin_maps(obj, path);
+	if (err)
+		return libbpf_err(err);
+
+	err = bpf_object__pin_programs(obj, path);
+	if (err) {
+		bpf_object__unpin_maps(obj, path);
+		return libbpf_err(err);
+	}
+
+	return 0;
+}
+
+static void bpf_map__destroy(struct bpf_map *map)
+{
+	if (map->inner_map) {
+		bpf_map__destroy(map->inner_map);
+		zfree(&map->inner_map);
+	}
+
+	zfree(&map->init_slots);
+	map->init_slots_sz = 0;
+
+	if (map->mmaped) {
+		munmap(map->mmaped, bpf_map_mmap_sz(map));
+		map->mmaped = NULL;
+	}
+
+	if (map->st_ops) {
+		zfree(&map->st_ops->data);
+		zfree(&map->st_ops->progs);
+		zfree(&map->st_ops->kern_func_off);
+		zfree(&map->st_ops);
+	}
+
+	zfree(&map->name);
+	zfree(&map->real_name);
+	zfree(&map->pin_path);
+
+	if (map->fd >= 0)
+		zclose(map->fd);
+}
+
+void bpf_object__close(struct bpf_object *obj)
+{
+	size_t i;
+
+	if (IS_ERR_OR_NULL(obj))
+		return;
+
+	usdt_manager_free(obj->usdt_man);
+	obj->usdt_man = NULL;
+
+	bpf_gen__free(obj->gen_loader);
+	bpf_object__elf_finish(obj);
+	bpf_object_unload(obj);
+	btf__free(obj->btf);
+	btf_ext__free(obj->btf_ext);
+
+	for (i = 0; i < obj->nr_maps; i++)
+		bpf_map__destroy(&obj->maps[i]);
+
+	zfree(&obj->btf_custom_path);
+	zfree(&obj->kconfig);
+	zfree(&obj->externs);
+	obj->nr_extern = 0;
+
+	zfree(&obj->maps);
+	obj->nr_maps = 0;
+
+	if (obj->programs && obj->nr_programs) {
+		for (i = 0; i < obj->nr_programs; i++)
+			bpf_program__exit(&obj->programs[i]);
+	}
+	zfree(&obj->programs);
+
+	free(obj);
+}
+
+const char *bpf_object__name(const struct bpf_object *obj)
+{
+	return obj ? obj->name : libbpf_err_ptr(-EINVAL);
+}
+
+unsigned int bpf_object__kversion(const struct bpf_object *obj)
+{
+	return obj ? obj->kern_version : 0;
+}
+
+struct btf *bpf_object__btf(const struct bpf_object *obj)
+{
+	return obj ? obj->btf : NULL;
+}
+
+int bpf_object__btf_fd(const struct bpf_object *obj)
+{
+	return obj->btf ? btf__fd(obj->btf) : -1;
+}
+
+int bpf_object__set_kversion(struct bpf_object *obj, __u32 kern_version)
+{
+	if (obj->loaded)
+		return libbpf_err(-EINVAL);
+
+	obj->kern_version = kern_version;
+
+	return 0;
+}
+
+int bpf_object__gen_loader(struct bpf_object *obj, struct gen_loader_opts *opts)
+{
+	struct bpf_gen *gen;
+
+	if (!opts)
+		return -EFAULT;
+	if (!OPTS_VALID(opts, gen_loader_opts))
+		return -EINVAL;
+	gen = calloc(sizeof(*gen), 1);
+	if (!gen)
+		return -ENOMEM;
+	gen->opts = opts;
+	obj->gen_loader = gen;
+	return 0;
+}
+
+static struct bpf_program *
+__bpf_program__iter(const struct bpf_program *p, const struct bpf_object *obj,
+		    bool forward)
+{
+	size_t nr_programs = obj->nr_programs;
+	ssize_t idx;
+
+	if (!nr_programs)
+		return NULL;
+
+	if (!p)
+		/* Iter from the beginning */
+		return forward ? &obj->programs[0] :
+			&obj->programs[nr_programs - 1];
+
+	if (p->obj != obj) {
+		pr_warn("error: program handler doesn't match object\n");
+		return errno = EINVAL, NULL;
+	}
+
+	idx = (p - obj->programs) + (forward ? 1 : -1);
+	if (idx >= obj->nr_programs || idx < 0)
+		return NULL;
+	return &obj->programs[idx];
+}
+
+struct bpf_program *
+bpf_object__next_program(const struct bpf_object *obj, struct bpf_program *prev)
+{
+	struct bpf_program *prog = prev;
+
+	do {
+		prog = __bpf_program__iter(prog, obj, true);
+	} while (prog && prog_is_subprog(obj, prog));
+
+	return prog;
+}
+
+struct bpf_program *
+bpf_object__prev_program(const struct bpf_object *obj, struct bpf_program *next)
+{
+	struct bpf_program *prog = next;
+
+	do {
+		prog = __bpf_program__iter(prog, obj, false);
+	} while (prog && prog_is_subprog(obj, prog));
+
+	return prog;
+}
+
+void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
+{
+	prog->prog_ifindex = ifindex;
+}
+
+const char *bpf_program__name(const struct bpf_program *prog)
+{
+	return prog->name;
+}
+
+const char *bpf_program__section_name(const struct bpf_program *prog)
+{
+	return prog->sec_name;
+}
+
+bool bpf_program__autoload(const struct bpf_program *prog)
+{
+	return prog->autoload;
+}
+
+int bpf_program__set_autoload(struct bpf_program *prog, bool autoload)
+{
+	if (prog->obj->loaded)
+		return libbpf_err(-EINVAL);
+
+	prog->autoload = autoload;
+	return 0;
+}
+
+bool bpf_program__autoattach(const struct bpf_program *prog)
+{
+	return prog->autoattach;
+}
+
+void bpf_program__set_autoattach(struct bpf_program *prog, bool autoattach)
+{
+	prog->autoattach = autoattach;
+}
+
+const struct bpf_insn *bpf_program__insns(const struct bpf_program *prog)
+{
+	return prog->insns;
+}
+
+size_t bpf_program__insn_cnt(const struct bpf_program *prog)
+{
+	return prog->insns_cnt;
+}
+
+int bpf_program__set_insns(struct bpf_program *prog,
+			   struct bpf_insn *new_insns, size_t new_insn_cnt)
+{
+	struct bpf_insn *insns;
+
+	if (prog->obj->loaded)
+		return -EBUSY;
+
+	insns = libbpf_reallocarray(prog->insns, new_insn_cnt, sizeof(*insns));
+	if (!insns) {
+		pr_warn("prog '%s': failed to realloc prog code\n", prog->name);
+		return -ENOMEM;
+	}
+	memcpy(insns, new_insns, new_insn_cnt * sizeof(*insns));
+
+	prog->insns = insns;
+	prog->insns_cnt = new_insn_cnt;
+	return 0;
+}
+
+int bpf_program__fd(const struct bpf_program *prog)
+{
+	if (!prog)
+		return libbpf_err(-EINVAL);
+
+	if (prog->fd < 0)
+		return libbpf_err(-ENOENT);
+
+	return prog->fd;
+}
+
+__alias(bpf_program__type)
+enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog);
+
+enum bpf_prog_type bpf_program__type(const struct bpf_program *prog)
+{
+	return prog->type;
+}
+
+int bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
+{
+	if (prog->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	prog->type = type;
+	return 0;
+}
+
+__alias(bpf_program__expected_attach_type)
+enum bpf_attach_type bpf_program__get_expected_attach_type(const struct bpf_program *prog);
+
+enum bpf_attach_type bpf_program__expected_attach_type(const struct bpf_program *prog)
+{
+	return prog->expected_attach_type;
+}
+
+int bpf_program__set_expected_attach_type(struct bpf_program *prog,
+					   enum bpf_attach_type type)
+{
+	if (prog->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	prog->expected_attach_type = type;
+	return 0;
+}
+
+__u32 bpf_program__flags(const struct bpf_program *prog)
+{
+	return prog->prog_flags;
+}
+
+int bpf_program__set_flags(struct bpf_program *prog, __u32 flags)
+{
+	if (prog->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	prog->prog_flags = flags;
+	return 0;
+}
+
+__u32 bpf_program__log_level(const struct bpf_program *prog)
+{
+	return prog->log_level;
+}
+
+int bpf_program__set_log_level(struct bpf_program *prog, __u32 log_level)
+{
+	if (prog->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	prog->log_level = log_level;
+	return 0;
+}
+
+const char *bpf_program__log_buf(const struct bpf_program *prog, size_t *log_size)
+{
+	*log_size = prog->log_size;
+	return prog->log_buf;
+}
+
+int bpf_program__set_log_buf(struct bpf_program *prog, char *log_buf, size_t log_size)
+{
+	if (log_size && !log_buf)
+		return -EINVAL;
+	if (prog->log_size > UINT_MAX)
+		return -EINVAL;
+	if (prog->obj->loaded)
+		return -EBUSY;
+
+	prog->log_buf = log_buf;
+	prog->log_size = log_size;
+	return 0;
+}
+
+#define SEC_DEF(sec_pfx, ptype, atype, flags, ...) {			    \
+	.sec = (char *)sec_pfx,						    \
+	.prog_type = BPF_PROG_TYPE_##ptype,				    \
+	.expected_attach_type = atype,					    \
+	.cookie = (long)(flags),					    \
+	.prog_prepare_load_fn = libbpf_prepare_prog_load,		    \
+	__VA_ARGS__							    \
+}
+
+static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_ksyscall(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_usdt(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+
+static const struct bpf_sec_def section_defs[] = {
+	SEC_DEF("socket",		SOCKET_FILTER, 0, SEC_NONE),
+	SEC_DEF("sk_reuseport/migrate",	SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, SEC_ATTACHABLE),
+	SEC_DEF("sk_reuseport",		SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT, SEC_ATTACHABLE),
+	SEC_DEF("kprobe+",		KPROBE,	0, SEC_NONE, attach_kprobe),
+	SEC_DEF("uprobe+",		KPROBE,	0, SEC_NONE, attach_uprobe),
+	SEC_DEF("uprobe.s+",		KPROBE,	0, SEC_SLEEPABLE, attach_uprobe),
+	SEC_DEF("kretprobe+",		KPROBE, 0, SEC_NONE, attach_kprobe),
+	SEC_DEF("uretprobe+",		KPROBE, 0, SEC_NONE, attach_uprobe),
+	SEC_DEF("uretprobe.s+",		KPROBE, 0, SEC_SLEEPABLE, attach_uprobe),
+	SEC_DEF("kprobe.multi+",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
+	SEC_DEF("kretprobe.multi+",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
+	SEC_DEF("ksyscall+",		KPROBE,	0, SEC_NONE, attach_ksyscall),
+	SEC_DEF("kretsyscall+",		KPROBE, 0, SEC_NONE, attach_ksyscall),
+	SEC_DEF("usdt+",		KPROBE,	0, SEC_NONE, attach_usdt),
+	SEC_DEF("tc",			SCHED_CLS, 0, SEC_NONE),
+	SEC_DEF("classifier",		SCHED_CLS, 0, SEC_NONE),
+	SEC_DEF("action",		SCHED_ACT, 0, SEC_NONE),
+	SEC_DEF("tracepoint+",		TRACEPOINT, 0, SEC_NONE, attach_tp),
+	SEC_DEF("tp+",			TRACEPOINT, 0, SEC_NONE, attach_tp),
+	SEC_DEF("raw_tracepoint+",	RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("raw_tp+",		RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("raw_tracepoint.w+",	RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("raw_tp.w+",		RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("tp_btf+",		TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fentry+",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fmod_ret+",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fexit+",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fentry.s+",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+	SEC_DEF("fmod_ret.s+",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+	SEC_DEF("fexit.s+",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+	SEC_DEF("freplace+",		EXT, 0, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("lsm+",			LSM, BPF_LSM_MAC, SEC_ATTACH_BTF, attach_lsm),
+	SEC_DEF("lsm.s+",		LSM, BPF_LSM_MAC, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_lsm),
+	SEC_DEF("lsm_cgroup+",		LSM, BPF_LSM_CGROUP, SEC_ATTACH_BTF),
+	SEC_DEF("iter+",		TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF, attach_iter),
+	SEC_DEF("iter.s+",		TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_iter),
+	SEC_DEF("syscall",		SYSCALL, 0, SEC_SLEEPABLE),
+	SEC_DEF("xdp.frags/devmap",	XDP, BPF_XDP_DEVMAP, SEC_XDP_FRAGS),
+	SEC_DEF("xdp/devmap",		XDP, BPF_XDP_DEVMAP, SEC_ATTACHABLE),
+	SEC_DEF("xdp.frags/cpumap",	XDP, BPF_XDP_CPUMAP, SEC_XDP_FRAGS),
+	SEC_DEF("xdp/cpumap",		XDP, BPF_XDP_CPUMAP, SEC_ATTACHABLE),
+	SEC_DEF("xdp.frags",		XDP, BPF_XDP, SEC_XDP_FRAGS),
+	SEC_DEF("xdp",			XDP, BPF_XDP, SEC_ATTACHABLE_OPT),
+	SEC_DEF("perf_event",		PERF_EVENT, 0, SEC_NONE),
+	SEC_DEF("lwt_in",		LWT_IN, 0, SEC_NONE),
+	SEC_DEF("lwt_out",		LWT_OUT, 0, SEC_NONE),
+	SEC_DEF("lwt_xmit",		LWT_XMIT, 0, SEC_NONE),
+	SEC_DEF("lwt_seg6local",	LWT_SEG6LOCAL, 0, SEC_NONE),
+	SEC_DEF("sockops",		SOCK_OPS, BPF_CGROUP_SOCK_OPS, SEC_ATTACHABLE_OPT),
+	SEC_DEF("sk_skb/stream_parser",	SK_SKB, BPF_SK_SKB_STREAM_PARSER, SEC_ATTACHABLE_OPT),
+	SEC_DEF("sk_skb/stream_verdict",SK_SKB, BPF_SK_SKB_STREAM_VERDICT, SEC_ATTACHABLE_OPT),
+	SEC_DEF("sk_skb",		SK_SKB, 0, SEC_NONE),
+	SEC_DEF("sk_msg",		SK_MSG, BPF_SK_MSG_VERDICT, SEC_ATTACHABLE_OPT),
+	SEC_DEF("lirc_mode2",		LIRC_MODE2, BPF_LIRC_MODE2, SEC_ATTACHABLE_OPT),
+	SEC_DEF("flow_dissector",	FLOW_DISSECTOR, BPF_FLOW_DISSECTOR, SEC_ATTACHABLE_OPT),
+	SEC_DEF("cgroup_skb/ingress",	CGROUP_SKB, BPF_CGROUP_INET_INGRESS, SEC_ATTACHABLE_OPT),
+	SEC_DEF("cgroup_skb/egress",	CGROUP_SKB, BPF_CGROUP_INET_EGRESS, SEC_ATTACHABLE_OPT),
+	SEC_DEF("cgroup/skb",		CGROUP_SKB, 0, SEC_NONE),
+	SEC_DEF("cgroup/sock_create",	CGROUP_SOCK, BPF_CGROUP_INET_SOCK_CREATE, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/sock_release",	CGROUP_SOCK, BPF_CGROUP_INET_SOCK_RELEASE, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/sock",		CGROUP_SOCK, BPF_CGROUP_INET_SOCK_CREATE, SEC_ATTACHABLE_OPT),
+	SEC_DEF("cgroup/post_bind4",	CGROUP_SOCK, BPF_CGROUP_INET4_POST_BIND, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/post_bind6",	CGROUP_SOCK, BPF_CGROUP_INET6_POST_BIND, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/bind4",		CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_BIND, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/bind6",		CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_BIND, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/connect4",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_CONNECT, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/connect6",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_CONNECT, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/sendmsg4",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP4_SENDMSG, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/sendmsg6",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP6_SENDMSG, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/recvmsg4",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP4_RECVMSG, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/recvmsg6",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP6_RECVMSG, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/getpeername4",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_GETPEERNAME, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/getpeername6",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_GETPEERNAME, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/getsockname4",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_GETSOCKNAME, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/getsockname6",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_GETSOCKNAME, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/sysctl",	CGROUP_SYSCTL, BPF_CGROUP_SYSCTL, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/getsockopt",	CGROUP_SOCKOPT, BPF_CGROUP_GETSOCKOPT, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/setsockopt",	CGROUP_SOCKOPT, BPF_CGROUP_SETSOCKOPT, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/dev",		CGROUP_DEVICE, BPF_CGROUP_DEVICE, SEC_ATTACHABLE_OPT),
+	SEC_DEF("struct_ops+",		STRUCT_OPS, 0, SEC_NONE),
+	SEC_DEF("sk_lookup",		SK_LOOKUP, BPF_SK_LOOKUP, SEC_ATTACHABLE),
+};
+
+static size_t custom_sec_def_cnt;
+static struct bpf_sec_def *custom_sec_defs;
+static struct bpf_sec_def custom_fallback_def;
+static bool has_custom_fallback_def;
+
+static int last_custom_sec_def_handler_id;
+
+int libbpf_register_prog_handler(const char *sec,
+				 enum bpf_prog_type prog_type,
+				 enum bpf_attach_type exp_attach_type,
+				 const struct libbpf_prog_handler_opts *opts)
+{
+	struct bpf_sec_def *sec_def;
+
+	if (!OPTS_VALID(opts, libbpf_prog_handler_opts))
+		return libbpf_err(-EINVAL);
+
+	if (last_custom_sec_def_handler_id == INT_MAX) /* prevent overflow */
+		return libbpf_err(-E2BIG);
+
+	if (sec) {
+		sec_def = libbpf_reallocarray(custom_sec_defs, custom_sec_def_cnt + 1,
+					      sizeof(*sec_def));
+		if (!sec_def)
+			return libbpf_err(-ENOMEM);
+
+		custom_sec_defs = sec_def;
+		sec_def = &custom_sec_defs[custom_sec_def_cnt];
+	} else {
+		if (has_custom_fallback_def)
+			return libbpf_err(-EBUSY);
+
+		sec_def = &custom_fallback_def;
+	}
+
+	sec_def->sec = sec ? strdup(sec) : NULL;
+	if (sec && !sec_def->sec)
+		return libbpf_err(-ENOMEM);
+
+	sec_def->prog_type = prog_type;
+	sec_def->expected_attach_type = exp_attach_type;
+	sec_def->cookie = OPTS_GET(opts, cookie, 0);
+
+	sec_def->prog_setup_fn = OPTS_GET(opts, prog_setup_fn, NULL);
+	sec_def->prog_prepare_load_fn = OPTS_GET(opts, prog_prepare_load_fn, NULL);
+	sec_def->prog_attach_fn = OPTS_GET(opts, prog_attach_fn, NULL);
+
+	sec_def->handler_id = ++last_custom_sec_def_handler_id;
+
+	if (sec)
+		custom_sec_def_cnt++;
+	else
+		has_custom_fallback_def = true;
+
+	return sec_def->handler_id;
+}
+
+int libbpf_unregister_prog_handler(int handler_id)
+{
+	struct bpf_sec_def *sec_defs;
+	int i;
+
+	if (handler_id <= 0)
+		return libbpf_err(-EINVAL);
+
+	if (has_custom_fallback_def && custom_fallback_def.handler_id == handler_id) {
+		memset(&custom_fallback_def, 0, sizeof(custom_fallback_def));
+		has_custom_fallback_def = false;
+		return 0;
+	}
+
+	for (i = 0; i < custom_sec_def_cnt; i++) {
+		if (custom_sec_defs[i].handler_id == handler_id)
+			break;
+	}
+
+	if (i == custom_sec_def_cnt)
+		return libbpf_err(-ENOENT);
+
+	free(custom_sec_defs[i].sec);
+	for (i = i + 1; i < custom_sec_def_cnt; i++)
+		custom_sec_defs[i - 1] = custom_sec_defs[i];
+	custom_sec_def_cnt--;
+
+	/* try to shrink the array, but it's ok if we couldn't */
+	sec_defs = libbpf_reallocarray(custom_sec_defs, custom_sec_def_cnt, sizeof(*sec_defs));
+	if (sec_defs)
+		custom_sec_defs = sec_defs;
+
+	return 0;
+}
+
+static bool sec_def_matches(const struct bpf_sec_def *sec_def, const char *sec_name)
+{
+	size_t len = strlen(sec_def->sec);
+
+	/* "type/" always has to have proper SEC("type/extras") form */
+	if (sec_def->sec[len - 1] == '/') {
+		if (str_has_pfx(sec_name, sec_def->sec))
+			return true;
+		return false;
+	}
+
+	/* "type+" means it can be either exact SEC("type") or
+	 * well-formed SEC("type/extras") with proper '/' separator
+	 */
+	if (sec_def->sec[len - 1] == '+') {
+		len--;
+		/* not even a prefix */
+		if (strncmp(sec_name, sec_def->sec, len) != 0)
+			return false;
+		/* exact match or has '/' separator */
+		if (sec_name[len] == '\0' || sec_name[len] == '/')
+			return true;
+		return false;
+	}
+
+	return strcmp(sec_name, sec_def->sec) == 0;
+}
+
+static const struct bpf_sec_def *find_sec_def(const char *sec_name)
+{
+	const struct bpf_sec_def *sec_def;
+	int i, n;
+
+	n = custom_sec_def_cnt;
+	for (i = 0; i < n; i++) {
+		sec_def = &custom_sec_defs[i];
+		if (sec_def_matches(sec_def, sec_name))
+			return sec_def;
+	}
+
+	n = ARRAY_SIZE(section_defs);
+	for (i = 0; i < n; i++) {
+		sec_def = &section_defs[i];
+		if (sec_def_matches(sec_def, sec_name))
+			return sec_def;
+	}
+
+	if (has_custom_fallback_def)
+		return &custom_fallback_def;
+
+	return NULL;
+}
+
+#define MAX_TYPE_NAME_SIZE 32
+
+static char *libbpf_get_type_names(bool attach_type)
+{
+	int i, len = ARRAY_SIZE(section_defs) * MAX_TYPE_NAME_SIZE;
+	char *buf;
+
+	buf = malloc(len);
+	if (!buf)
+		return NULL;
+
+	buf[0] = '\0';
+	/* Forge string buf with all available names */
+	for (i = 0; i < ARRAY_SIZE(section_defs); i++) {
+		const struct bpf_sec_def *sec_def = &section_defs[i];
+
+		if (attach_type) {
+			if (sec_def->prog_prepare_load_fn != libbpf_prepare_prog_load)
+				continue;
+
+			if (!(sec_def->cookie & SEC_ATTACHABLE))
+				continue;
+		}
+
+		if (strlen(buf) + strlen(section_defs[i].sec) + 2 > len) {
+			free(buf);
+			return NULL;
+		}
+		strcat(buf, " ");
+		strcat(buf, section_defs[i].sec);
+	}
+
+	return buf;
+}
+
+int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
+			     enum bpf_attach_type *expected_attach_type)
+{
+	const struct bpf_sec_def *sec_def;
+	char *type_names;
+
+	if (!name)
+		return libbpf_err(-EINVAL);
+
+	sec_def = find_sec_def(name);
+	if (sec_def) {
+		*prog_type = sec_def->prog_type;
+		*expected_attach_type = sec_def->expected_attach_type;
+		return 0;
+	}
+
+	pr_debug("failed to guess program type from ELF section '%s'\n", name);
+	type_names = libbpf_get_type_names(false);
+	if (type_names != NULL) {
+		pr_debug("supported section(type) names are:%s\n", type_names);
+		free(type_names);
+	}
+
+	return libbpf_err(-ESRCH);
+}
+
+const char *libbpf_bpf_attach_type_str(enum bpf_attach_type t)
+{
+	if (t < 0 || t >= ARRAY_SIZE(attach_type_name))
+		return NULL;
+
+	return attach_type_name[t];
+}
+
+const char *libbpf_bpf_link_type_str(enum bpf_link_type t)
+{
+	if (t < 0 || t >= ARRAY_SIZE(link_type_name))
+		return NULL;
+
+	return link_type_name[t];
+}
+
+const char *libbpf_bpf_map_type_str(enum bpf_map_type t)
+{
+	if (t < 0 || t >= ARRAY_SIZE(map_type_name))
+		return NULL;
+
+	return map_type_name[t];
+}
+
+const char *libbpf_bpf_prog_type_str(enum bpf_prog_type t)
+{
+	if (t < 0 || t >= ARRAY_SIZE(prog_type_name))
+		return NULL;
+
+	return prog_type_name[t];
+}
+
+static struct bpf_map *find_struct_ops_map_by_offset(struct bpf_object *obj,
+						     size_t offset)
+{
+	struct bpf_map *map;
+	size_t i;
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		map = &obj->maps[i];
+		if (!bpf_map__is_struct_ops(map))
+			continue;
+		if (map->sec_offset <= offset &&
+		    offset - map->sec_offset < map->def.value_size)
+			return map;
+	}
+
+	return NULL;
+}
+
+/* Collect the reloc from ELF and populate the st_ops->progs[] */
+static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
+					    Elf64_Shdr *shdr, Elf_Data *data)
+{
+	const struct btf_member *member;
+	struct bpf_struct_ops *st_ops;
+	struct bpf_program *prog;
+	unsigned int shdr_idx;
+	const struct btf *btf;
+	struct bpf_map *map;
+	unsigned int moff, insn_idx;
+	const char *name;
+	__u32 member_idx;
+	Elf64_Sym *sym;
+	Elf64_Rel *rel;
+	int i, nrels;
+
+	btf = obj->btf;
+	nrels = shdr->sh_size / shdr->sh_entsize;
+	for (i = 0; i < nrels; i++) {
+		rel = elf_rel_by_idx(data, i);
+		if (!rel) {
+			pr_warn("struct_ops reloc: failed to get %d reloc\n", i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info));
+		if (!sym) {
+			pr_warn("struct_ops reloc: symbol %zx not found\n",
+				(size_t)ELF64_R_SYM(rel->r_info));
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		name = elf_sym_str(obj, sym->st_name) ?: "<?>";
+		map = find_struct_ops_map_by_offset(obj, rel->r_offset);
+		if (!map) {
+			pr_warn("struct_ops reloc: cannot find map at rel->r_offset %zu\n",
+				(size_t)rel->r_offset);
+			return -EINVAL;
+		}
+
+		moff = rel->r_offset - map->sec_offset;
+		shdr_idx = sym->st_shndx;
+		st_ops = map->st_ops;
+		pr_debug("struct_ops reloc %s: for %lld value %lld shdr_idx %u rel->r_offset %zu map->sec_offset %zu name %d (\'%s\')\n",
+			 map->name,
+			 (long long)(rel->r_info >> 32),
+			 (long long)sym->st_value,
+			 shdr_idx, (size_t)rel->r_offset,
+			 map->sec_offset, sym->st_name, name);
+
+		if (shdr_idx >= SHN_LORESERVE) {
+			pr_warn("struct_ops reloc %s: rel->r_offset %zu shdr_idx %u unsupported non-static function\n",
+				map->name, (size_t)rel->r_offset, shdr_idx);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		if (sym->st_value % BPF_INSN_SZ) {
+			pr_warn("struct_ops reloc %s: invalid target program offset %llu\n",
+				map->name, (unsigned long long)sym->st_value);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+		insn_idx = sym->st_value / BPF_INSN_SZ;
+
+		member = find_member_by_offset(st_ops->type, moff * 8);
+		if (!member) {
+			pr_warn("struct_ops reloc %s: cannot find member at moff %u\n",
+				map->name, moff);
+			return -EINVAL;
+		}
+		member_idx = member - btf_members(st_ops->type);
+		name = btf__name_by_offset(btf, member->name_off);
+
+		if (!resolve_func_ptr(btf, member->type, NULL)) {
+			pr_warn("struct_ops reloc %s: cannot relocate non func ptr %s\n",
+				map->name, name);
+			return -EINVAL;
+		}
+
+		prog = find_prog_by_sec_insn(obj, shdr_idx, insn_idx);
+		if (!prog) {
+			pr_warn("struct_ops reloc %s: cannot find prog at shdr_idx %u to relocate func ptr %s\n",
+				map->name, shdr_idx, name);
+			return -EINVAL;
+		}
+
+		/* prevent the use of BPF prog with invalid type */
+		if (prog->type != BPF_PROG_TYPE_STRUCT_OPS) {
+			pr_warn("struct_ops reloc %s: prog %s is not struct_ops BPF program\n",
+				map->name, prog->name);
+			return -EINVAL;
+		}
+
+		/* if we haven't yet processed this BPF program, record proper
+		 * attach_btf_id and member_idx
+		 */
+		if (!prog->attach_btf_id) {
+			prog->attach_btf_id = st_ops->type_id;
+			prog->expected_attach_type = member_idx;
+		}
+
+		/* struct_ops BPF prog can be re-used between multiple
+		 * .struct_ops as long as it's the same struct_ops struct
+		 * definition and the same function pointer field
+		 */
+		if (prog->attach_btf_id != st_ops->type_id ||
+		    prog->expected_attach_type != member_idx) {
+			pr_warn("struct_ops reloc %s: cannot use prog %s in sec %s with type %u attach_btf_id %u expected_attach_type %u for func ptr %s\n",
+				map->name, prog->name, prog->sec_name, prog->type,
+				prog->attach_btf_id, prog->expected_attach_type, name);
+			return -EINVAL;
+		}
+
+		st_ops->progs[member_idx] = prog;
+	}
+
+	return 0;
+}
+
+#define BTF_TRACE_PREFIX "btf_trace_"
+#define BTF_LSM_PREFIX "bpf_lsm_"
+#define BTF_ITER_PREFIX "bpf_iter_"
+#define BTF_MAX_NAME_SIZE 128
+
+void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,
+				const char **prefix, int *kind)
+{
+	switch (attach_type) {
+	case BPF_TRACE_RAW_TP:
+		*prefix = BTF_TRACE_PREFIX;
+		*kind = BTF_KIND_TYPEDEF;
+		break;
+	case BPF_LSM_MAC:
+	case BPF_LSM_CGROUP:
+		*prefix = BTF_LSM_PREFIX;
+		*kind = BTF_KIND_FUNC;
+		break;
+	case BPF_TRACE_ITER:
+		*prefix = BTF_ITER_PREFIX;
+		*kind = BTF_KIND_FUNC;
+		break;
+	default:
+		*prefix = "";
+		*kind = BTF_KIND_FUNC;
+	}
+}
+
+static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
+				   const char *name, __u32 kind)
+{
+	char btf_type_name[BTF_MAX_NAME_SIZE];
+	int ret;
+
+	ret = snprintf(btf_type_name, sizeof(btf_type_name),
+		       "%s%s", prefix, name);
+	/* snprintf returns the number of characters written excluding the
+	 * terminating null. So, if >= BTF_MAX_NAME_SIZE are written, it
+	 * indicates truncation.
+	 */
+	if (ret < 0 || ret >= sizeof(btf_type_name))
+		return -ENAMETOOLONG;
+	return btf__find_by_name_kind(btf, btf_type_name, kind);
+}
+
+static inline int find_attach_btf_id(struct btf *btf, const char *name,
+				     enum bpf_attach_type attach_type)
+{
+	const char *prefix;
+	int kind;
+
+	btf_get_kernel_prefix_kind(attach_type, &prefix, &kind);
+	return find_btf_by_prefix_kind(btf, prefix, name, kind);
+}
+
+int libbpf_find_vmlinux_btf_id(const char *name,
+			       enum bpf_attach_type attach_type)
+{
+	struct btf *btf;
+	int err;
+
+	btf = btf__load_vmlinux_btf();
+	err = libbpf_get_error(btf);
+	if (err) {
+		pr_warn("vmlinux BTF is not found\n");
+		return libbpf_err(err);
+	}
+
+	err = find_attach_btf_id(btf, name, attach_type);
+	if (err <= 0)
+		pr_warn("%s is not found in vmlinux BTF\n", name);
+
+	btf__free(btf);
+	return libbpf_err(err);
+}
+
+static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
+{
+	struct bpf_prog_info info;
+	__u32 info_len = sizeof(info);
+	struct btf *btf;
+	int err;
+
+	memset(&info, 0, info_len);
+	err = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len);
+	if (err) {
+		pr_warn("failed bpf_obj_get_info_by_fd for FD %d: %d\n",
+			attach_prog_fd, err);
+		return err;
+	}
+
+	err = -EINVAL;
+	if (!info.btf_id) {
+		pr_warn("The target program doesn't have BTF\n");
+		goto out;
+	}
+	btf = btf__load_from_kernel_by_id(info.btf_id);
+	err = libbpf_get_error(btf);
+	if (err) {
+		pr_warn("Failed to get BTF %d of the program: %d\n", info.btf_id, err);
+		goto out;
+	}
+	err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
+	btf__free(btf);
+	if (err <= 0) {
+		pr_warn("%s is not found in prog's BTF\n", name);
+		goto out;
+	}
+out:
+	return err;
+}
+
+static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name,
+			      enum bpf_attach_type attach_type,
+			      int *btf_obj_fd, int *btf_type_id)
+{
+	int ret, i;
+
+	ret = find_attach_btf_id(obj->btf_vmlinux, attach_name, attach_type);
+	if (ret > 0) {
+		*btf_obj_fd = 0; /* vmlinux BTF */
+		*btf_type_id = ret;
+		return 0;
+	}
+	if (ret != -ENOENT)
+		return ret;
+
+	ret = load_module_btfs(obj);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < obj->btf_module_cnt; i++) {
+		const struct module_btf *mod = &obj->btf_modules[i];
+
+		ret = find_attach_btf_id(mod->btf, attach_name, attach_type);
+		if (ret > 0) {
+			*btf_obj_fd = mod->fd;
+			*btf_type_id = ret;
+			return 0;
+		}
+		if (ret == -ENOENT)
+			continue;
+
+		return ret;
+	}
+
+	return -ESRCH;
+}
+
+static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attach_name,
+				     int *btf_obj_fd, int *btf_type_id)
+{
+	enum bpf_attach_type attach_type = prog->expected_attach_type;
+	__u32 attach_prog_fd = prog->attach_prog_fd;
+	int err = 0;
+
+	/* BPF program's BTF ID */
+	if (prog->type == BPF_PROG_TYPE_EXT || attach_prog_fd) {
+		if (!attach_prog_fd) {
+			pr_warn("prog '%s': attach program FD is not set\n", prog->name);
+			return -EINVAL;
+		}
+		err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd);
+		if (err < 0) {
+			pr_warn("prog '%s': failed to find BPF program (FD %d) BTF ID for '%s': %d\n",
+				 prog->name, attach_prog_fd, attach_name, err);
+			return err;
+		}
+		*btf_obj_fd = 0;
+		*btf_type_id = err;
+		return 0;
+	}
+
+	/* kernel/module BTF ID */
+	if (prog->obj->gen_loader) {
+		bpf_gen__record_attach_target(prog->obj->gen_loader, attach_name, attach_type);
+		*btf_obj_fd = 0;
+		*btf_type_id = 1;
+	} else {
+		err = find_kernel_btf_id(prog->obj, attach_name, attach_type, btf_obj_fd, btf_type_id);
+	}
+	if (err) {
+		pr_warn("prog '%s': failed to find kernel BTF type ID of '%s': %d\n",
+			prog->name, attach_name, err);
+		return err;
+	}
+	return 0;
+}
+
+int libbpf_attach_type_by_name(const char *name,
+			       enum bpf_attach_type *attach_type)
+{
+	char *type_names;
+	const struct bpf_sec_def *sec_def;
+
+	if (!name)
+		return libbpf_err(-EINVAL);
+
+	sec_def = find_sec_def(name);
+	if (!sec_def) {
+		pr_debug("failed to guess attach type based on ELF section name '%s'\n", name);
+		type_names = libbpf_get_type_names(true);
+		if (type_names != NULL) {
+			pr_debug("attachable section(type) names are:%s\n", type_names);
+			free(type_names);
+		}
+
+		return libbpf_err(-EINVAL);
+	}
+
+	if (sec_def->prog_prepare_load_fn != libbpf_prepare_prog_load)
+		return libbpf_err(-EINVAL);
+	if (!(sec_def->cookie & SEC_ATTACHABLE))
+		return libbpf_err(-EINVAL);
+
+	*attach_type = sec_def->expected_attach_type;
+	return 0;
+}
+
+int bpf_map__fd(const struct bpf_map *map)
+{
+	return map ? map->fd : libbpf_err(-EINVAL);
+}
+
+static bool map_uses_real_name(const struct bpf_map *map)
+{
+	/* Since libbpf started to support custom .data.* and .rodata.* maps,
+	 * their user-visible name differs from kernel-visible name. Users see
+	 * such map's corresponding ELF section name as a map name.
+	 * This check distinguishes .data/.rodata from .data.* and .rodata.*
+	 * maps to know which name has to be returned to the user.
+	 */
+	if (map->libbpf_type == LIBBPF_MAP_DATA && strcmp(map->real_name, DATA_SEC) != 0)
+		return true;
+	if (map->libbpf_type == LIBBPF_MAP_RODATA && strcmp(map->real_name, RODATA_SEC) != 0)
+		return true;
+	return false;
+}
+
+const char *bpf_map__name(const struct bpf_map *map)
+{
+	if (!map)
+		return NULL;
+
+	if (map_uses_real_name(map))
+		return map->real_name;
+
+	return map->name;
+}
+
+enum bpf_map_type bpf_map__type(const struct bpf_map *map)
+{
+	return map->def.type;
+}
+
+int bpf_map__set_type(struct bpf_map *map, enum bpf_map_type type)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->def.type = type;
+	return 0;
+}
+
+__u32 bpf_map__map_flags(const struct bpf_map *map)
+{
+	return map->def.map_flags;
+}
+
+int bpf_map__set_map_flags(struct bpf_map *map, __u32 flags)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->def.map_flags = flags;
+	return 0;
+}
+
+__u64 bpf_map__map_extra(const struct bpf_map *map)
+{
+	return map->map_extra;
+}
+
+int bpf_map__set_map_extra(struct bpf_map *map, __u64 map_extra)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->map_extra = map_extra;
+	return 0;
+}
+
+__u32 bpf_map__numa_node(const struct bpf_map *map)
+{
+	return map->numa_node;
+}
+
+int bpf_map__set_numa_node(struct bpf_map *map, __u32 numa_node)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->numa_node = numa_node;
+	return 0;
+}
+
+__u32 bpf_map__key_size(const struct bpf_map *map)
+{
+	return map->def.key_size;
+}
+
+int bpf_map__set_key_size(struct bpf_map *map, __u32 size)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->def.key_size = size;
+	return 0;
+}
+
+__u32 bpf_map__value_size(const struct bpf_map *map)
+{
+	return map->def.value_size;
+}
+
+int bpf_map__set_value_size(struct bpf_map *map, __u32 size)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->def.value_size = size;
+	return 0;
+}
+
+__u32 bpf_map__btf_key_type_id(const struct bpf_map *map)
+{
+	return map ? map->btf_key_type_id : 0;
+}
+
+__u32 bpf_map__btf_value_type_id(const struct bpf_map *map)
+{
+	return map ? map->btf_value_type_id : 0;
+}
+
+int bpf_map__set_initial_value(struct bpf_map *map,
+			       const void *data, size_t size)
+{
+	if (!map->mmaped || map->libbpf_type == LIBBPF_MAP_KCONFIG ||
+	    size != map->def.value_size || map->fd >= 0)
+		return libbpf_err(-EINVAL);
+
+	memcpy(map->mmaped, data, size);
+	return 0;
+}
+
+const void *bpf_map__initial_value(struct bpf_map *map, size_t *psize)
+{
+	if (!map->mmaped)
+		return NULL;
+	*psize = map->def.value_size;
+	return map->mmaped;
+}
+
+bool bpf_map__is_internal(const struct bpf_map *map)
+{
+	return map->libbpf_type != LIBBPF_MAP_UNSPEC;
+}
+
+__u32 bpf_map__ifindex(const struct bpf_map *map)
+{
+	return map->map_ifindex;
+}
+
+int bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->map_ifindex = ifindex;
+	return 0;
+}
+
+int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)
+{
+	if (!bpf_map_type__is_map_in_map(map->def.type)) {
+		pr_warn("error: unsupported map type\n");
+		return libbpf_err(-EINVAL);
+	}
+	if (map->inner_map_fd != -1) {
+		pr_warn("error: inner_map_fd already specified\n");
+		return libbpf_err(-EINVAL);
+	}
+	if (map->inner_map) {
+		bpf_map__destroy(map->inner_map);
+		zfree(&map->inner_map);
+	}
+	map->inner_map_fd = fd;
+	return 0;
+}
+
+static struct bpf_map *
+__bpf_map__iter(const struct bpf_map *m, const struct bpf_object *obj, int i)
+{
+	ssize_t idx;
+	struct bpf_map *s, *e;
+
+	if (!obj || !obj->maps)
+		return errno = EINVAL, NULL;
+
+	s = obj->maps;
+	e = obj->maps + obj->nr_maps;
+
+	if ((m < s) || (m >= e)) {
+		pr_warn("error in %s: map handler doesn't belong to object\n",
+			 __func__);
+		return errno = EINVAL, NULL;
+	}
+
+	idx = (m - obj->maps) + i;
+	if (idx >= obj->nr_maps || idx < 0)
+		return NULL;
+	return &obj->maps[idx];
+}
+
+struct bpf_map *
+bpf_object__next_map(const struct bpf_object *obj, const struct bpf_map *prev)
+{
+	if (prev == NULL)
+		return obj->maps;
+
+	return __bpf_map__iter(prev, obj, 1);
+}
+
+struct bpf_map *
+bpf_object__prev_map(const struct bpf_object *obj, const struct bpf_map *next)
+{
+	if (next == NULL) {
+		if (!obj->nr_maps)
+			return NULL;
+		return obj->maps + obj->nr_maps - 1;
+	}
+
+	return __bpf_map__iter(next, obj, -1);
+}
+
+struct bpf_map *
+bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name)
+{
+	struct bpf_map *pos;
+
+	bpf_object__for_each_map(pos, obj) {
+		/* if it's a special internal map name (which always starts
+		 * with dot) then check if that special name matches the
+		 * real map name (ELF section name)
+		 */
+		if (name[0] == '.') {
+			if (pos->real_name && strcmp(pos->real_name, name) == 0)
+				return pos;
+			continue;
+		}
+		/* otherwise map name has to be an exact match */
+		if (map_uses_real_name(pos)) {
+			if (strcmp(pos->real_name, name) == 0)
+				return pos;
+			continue;
+		}
+		if (strcmp(pos->name, name) == 0)
+			return pos;
+	}
+	return errno = ENOENT, NULL;
+}
+
+int
+bpf_object__find_map_fd_by_name(const struct bpf_object *obj, const char *name)
+{
+	return bpf_map__fd(bpf_object__find_map_by_name(obj, name));
+}
+
+static int validate_map_op(const struct bpf_map *map, size_t key_sz,
+			   size_t value_sz, bool check_value_sz)
+{
+	if (map->fd <= 0)
+		return -ENOENT;
+
+	if (map->def.key_size != key_sz) {
+		pr_warn("map '%s': unexpected key size %zu provided, expected %u\n",
+			map->name, key_sz, map->def.key_size);
+		return -EINVAL;
+	}
+
+	if (!check_value_sz)
+		return 0;
+
+	switch (map->def.type) {
+	case BPF_MAP_TYPE_PERCPU_ARRAY:
+	case BPF_MAP_TYPE_PERCPU_HASH:
+	case BPF_MAP_TYPE_LRU_PERCPU_HASH:
+	case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE: {
+		int num_cpu = libbpf_num_possible_cpus();
+		size_t elem_sz = roundup(map->def.value_size, 8);
+
+		if (value_sz != num_cpu * elem_sz) {
+			pr_warn("map '%s': unexpected value size %zu provided for per-CPU map, expected %d * %zu = %zd\n",
+				map->name, value_sz, num_cpu, elem_sz, num_cpu * elem_sz);
+			return -EINVAL;
+		}
+		break;
+	}
+	default:
+		if (map->def.value_size != value_sz) {
+			pr_warn("map '%s': unexpected value size %zu provided, expected %u\n",
+				map->name, value_sz, map->def.value_size);
+			return -EINVAL;
+		}
+		break;
+	}
+	return 0;
+}
+
+int bpf_map__lookup_elem(const struct bpf_map *map,
+			 const void *key, size_t key_sz,
+			 void *value, size_t value_sz, __u64 flags)
+{
+	int err;
+
+	err = validate_map_op(map, key_sz, value_sz, true);
+	if (err)
+		return libbpf_err(err);
+
+	return bpf_map_lookup_elem_flags(map->fd, key, value, flags);
+}
+
+int bpf_map__update_elem(const struct bpf_map *map,
+			 const void *key, size_t key_sz,
+			 const void *value, size_t value_sz, __u64 flags)
+{
+	int err;
+
+	err = validate_map_op(map, key_sz, value_sz, true);
+	if (err)
+		return libbpf_err(err);
+
+	return bpf_map_update_elem(map->fd, key, value, flags);
+}
+
+int bpf_map__delete_elem(const struct bpf_map *map,
+			 const void *key, size_t key_sz, __u64 flags)
+{
+	int err;
+
+	err = validate_map_op(map, key_sz, 0, false /* check_value_sz */);
+	if (err)
+		return libbpf_err(err);
+
+	return bpf_map_delete_elem_flags(map->fd, key, flags);
+}
+
+int bpf_map__lookup_and_delete_elem(const struct bpf_map *map,
+				    const void *key, size_t key_sz,
+				    void *value, size_t value_sz, __u64 flags)
+{
+	int err;
+
+	err = validate_map_op(map, key_sz, value_sz, true);
+	if (err)
+		return libbpf_err(err);
+
+	return bpf_map_lookup_and_delete_elem_flags(map->fd, key, value, flags);
+}
+
+int bpf_map__get_next_key(const struct bpf_map *map,
+			  const void *cur_key, void *next_key, size_t key_sz)
+{
+	int err;
+
+	err = validate_map_op(map, key_sz, 0, false /* check_value_sz */);
+	if (err)
+		return libbpf_err(err);
+
+	return bpf_map_get_next_key(map->fd, cur_key, next_key);
+}
+
+long libbpf_get_error(const void *ptr)
+{
+	if (!IS_ERR_OR_NULL(ptr))
+		return 0;
+
+	if (IS_ERR(ptr))
+		errno = -PTR_ERR(ptr);
+
+	/* If ptr == NULL, then errno should be already set by the failing
+	 * API, because libbpf never returns NULL on success and it now always
+	 * sets errno on error. So no extra errno handling for ptr == NULL
+	 * case.
+	 */
+	return -errno;
+}
+
+/* Replace link's underlying BPF program with the new one */
+int bpf_link__update_program(struct bpf_link *link, struct bpf_program *prog)
+{
+	int ret;
+
+	ret = bpf_link_update(bpf_link__fd(link), bpf_program__fd(prog), NULL);
+	return libbpf_err_errno(ret);
+}
+
+/* Release "ownership" of underlying BPF resource (typically, BPF program
+ * attached to some BPF hook, e.g., tracepoint, kprobe, etc). Disconnected
+ * link, when destructed through bpf_link__destroy() call won't attempt to
+ * detach/unregisted that BPF resource. This is useful in situations where,
+ * say, attached BPF program has to outlive userspace program that attached it
+ * in the system. Depending on type of BPF program, though, there might be
+ * additional steps (like pinning BPF program in BPF FS) necessary to ensure
+ * exit of userspace program doesn't trigger automatic detachment and clean up
+ * inside the kernel.
+ */
+void bpf_link__disconnect(struct bpf_link *link)
+{
+	link->disconnected = true;
+}
+
+int bpf_link__destroy(struct bpf_link *link)
+{
+	int err = 0;
+
+	if (IS_ERR_OR_NULL(link))
+		return 0;
+
+	if (!link->disconnected && link->detach)
+		err = link->detach(link);
+	if (link->pin_path)
+		free(link->pin_path);
+	if (link->dealloc)
+		link->dealloc(link);
+	else
+		free(link);
+
+	return libbpf_err(err);
+}
+
+int bpf_link__fd(const struct bpf_link *link)
+{
+	return link->fd;
+}
+
+const char *bpf_link__pin_path(const struct bpf_link *link)
+{
+	return link->pin_path;
+}
+
+static int bpf_link__detach_fd(struct bpf_link *link)
+{
+	return libbpf_err_errno(close(link->fd));
+}
+
+struct bpf_link *bpf_link__open(const char *path)
+{
+	struct bpf_link *link;
+	int fd;
+
+	fd = bpf_obj_get(path);
+	if (fd < 0) {
+		fd = -errno;
+		pr_warn("failed to open link at %s: %d\n", path, fd);
+		return libbpf_err_ptr(fd);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link) {
+		close(fd);
+		return libbpf_err_ptr(-ENOMEM);
+	}
+	link->detach = &bpf_link__detach_fd;
+	link->fd = fd;
+
+	link->pin_path = strdup(path);
+	if (!link->pin_path) {
+		bpf_link__destroy(link);
+		return libbpf_err_ptr(-ENOMEM);
+	}
+
+	return link;
+}
+
+int bpf_link__detach(struct bpf_link *link)
+{
+	return bpf_link_detach(link->fd) ? -errno : 0;
+}
+
+int bpf_link__pin(struct bpf_link *link, const char *path)
+{
+	int err;
+
+	if (link->pin_path)
+		return libbpf_err(-EBUSY);
+	err = make_parent_dir(path);
+	if (err)
+		return libbpf_err(err);
+	err = check_path(path);
+	if (err)
+		return libbpf_err(err);
+
+	link->pin_path = strdup(path);
+	if (!link->pin_path)
+		return libbpf_err(-ENOMEM);
+
+	if (bpf_obj_pin(link->fd, link->pin_path)) {
+		err = -errno;
+		zfree(&link->pin_path);
+		return libbpf_err(err);
+	}
+
+	pr_debug("link fd=%d: pinned at %s\n", link->fd, link->pin_path);
+	return 0;
+}
+
+int bpf_link__unpin(struct bpf_link *link)
+{
+	int err;
+
+	if (!link->pin_path)
+		return libbpf_err(-EINVAL);
+
+	err = unlink(link->pin_path);
+	if (err != 0)
+		return -errno;
+
+	pr_debug("link fd=%d: unpinned from %s\n", link->fd, link->pin_path);
+	zfree(&link->pin_path);
+	return 0;
+}
+
+struct bpf_link_perf {
+	struct bpf_link link;
+	int perf_event_fd;
+	/* legacy kprobe support: keep track of probe identifier and type */
+	char *legacy_probe_name;
+	bool legacy_is_kprobe;
+	bool legacy_is_retprobe;
+};
+
+static int remove_kprobe_event_legacy(const char *probe_name, bool retprobe);
+static int remove_uprobe_event_legacy(const char *probe_name, bool retprobe);
+
+static int bpf_link_perf_detach(struct bpf_link *link)
+{
+	struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
+	int err = 0;
+
+	if (ioctl(perf_link->perf_event_fd, PERF_EVENT_IOC_DISABLE, 0) < 0)
+		err = -errno;
+
+	if (perf_link->perf_event_fd != link->fd)
+		close(perf_link->perf_event_fd);
+	close(link->fd);
+
+	/* legacy uprobe/kprobe needs to be removed after perf event fd closure */
+	if (perf_link->legacy_probe_name) {
+		if (perf_link->legacy_is_kprobe) {
+			err = remove_kprobe_event_legacy(perf_link->legacy_probe_name,
+							 perf_link->legacy_is_retprobe);
+		} else {
+			err = remove_uprobe_event_legacy(perf_link->legacy_probe_name,
+							 perf_link->legacy_is_retprobe);
+		}
+	}
+
+	return err;
+}
+
+static void bpf_link_perf_dealloc(struct bpf_link *link)
+{
+	struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
+
+	free(perf_link->legacy_probe_name);
+	free(perf_link);
+}
+
+struct bpf_link *bpf_program__attach_perf_event_opts(const struct bpf_program *prog, int pfd,
+						     const struct bpf_perf_event_opts *opts)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link_perf *link;
+	int prog_fd, link_fd = -1, err;
+
+	if (!OPTS_VALID(opts, bpf_perf_event_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	if (pfd < 0) {
+		pr_warn("prog '%s': invalid perf event FD %d\n",
+			prog->name, pfd);
+		return libbpf_err_ptr(-EINVAL);
+	}
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("prog '%s': can't attach BPF program w/o FD (did you load it?)\n",
+			prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->link.detach = &bpf_link_perf_detach;
+	link->link.dealloc = &bpf_link_perf_dealloc;
+	link->perf_event_fd = pfd;
+
+	if (kernel_supports(prog->obj, FEAT_PERF_LINK)) {
+		DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_opts,
+			.perf_event.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0));
+
+		link_fd = bpf_link_create(prog_fd, pfd, BPF_PERF_EVENT, &link_opts);
+		if (link_fd < 0) {
+			err = -errno;
+			pr_warn("prog '%s': failed to create BPF link for perf_event FD %d: %d (%s)\n",
+				prog->name, pfd,
+				err, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+			goto err_out;
+		}
+		link->link.fd = link_fd;
+	} else {
+		if (OPTS_GET(opts, bpf_cookie, 0)) {
+			pr_warn("prog '%s': user context value is not supported\n", prog->name);
+			err = -EOPNOTSUPP;
+			goto err_out;
+		}
+
+		if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
+			err = -errno;
+			pr_warn("prog '%s': failed to attach to perf_event FD %d: %s\n",
+				prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+			if (err == -EPROTO)
+				pr_warn("prog '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n",
+					prog->name, pfd);
+			goto err_out;
+		}
+		link->link.fd = pfd;
+	}
+	if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
+		err = -errno;
+		pr_warn("prog '%s': failed to enable perf_event FD %d: %s\n",
+			prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_out;
+	}
+
+	return &link->link;
+err_out:
+	if (link_fd >= 0)
+		close(link_fd);
+	free(link);
+	return libbpf_err_ptr(err);
+}
+
+struct bpf_link *bpf_program__attach_perf_event(const struct bpf_program *prog, int pfd)
+{
+	return bpf_program__attach_perf_event_opts(prog, pfd, NULL);
+}
+
+/*
+ * this function is expected to parse integer in the range of [0, 2^31-1] from
+ * given file using scanf format string fmt. If actual parsed value is
+ * negative, the result might be indistinguishable from error
+ */
+static int parse_uint_from_file(const char *file, const char *fmt)
+{
+	char buf[STRERR_BUFSIZE];
+	int err, ret;
+	FILE *f;
+
+	f = fopen(file, "r");
+	if (!f) {
+		err = -errno;
+		pr_debug("failed to open '%s': %s\n", file,
+			 libbpf_strerror_r(err, buf, sizeof(buf)));
+		return err;
+	}
+	err = fscanf(f, fmt, &ret);
+	if (err != 1) {
+		err = err == EOF ? -EIO : -errno;
+		pr_debug("failed to parse '%s': %s\n", file,
+			libbpf_strerror_r(err, buf, sizeof(buf)));
+		fclose(f);
+		return err;
+	}
+	fclose(f);
+	return ret;
+}
+
+static int determine_kprobe_perf_type(void)
+{
+	const char *file = "/sys/bus/event_source/devices/kprobe/type";
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int determine_uprobe_perf_type(void)
+{
+	const char *file = "/sys/bus/event_source/devices/uprobe/type";
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int determine_kprobe_retprobe_bit(void)
+{
+	const char *file = "/sys/bus/event_source/devices/kprobe/format/retprobe";
+
+	return parse_uint_from_file(file, "config:%d\n");
+}
+
+static int determine_uprobe_retprobe_bit(void)
+{
+	const char *file = "/sys/bus/event_source/devices/uprobe/format/retprobe";
+
+	return parse_uint_from_file(file, "config:%d\n");
+}
+
+#define PERF_UPROBE_REF_CTR_OFFSET_BITS 32
+#define PERF_UPROBE_REF_CTR_OFFSET_SHIFT 32
+
+static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
+				 uint64_t offset, int pid, size_t ref_ctr_off)
+{
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_event_attr attr;
+	char errmsg[STRERR_BUFSIZE];
+	int type, pfd;
+
+	if ((__u64)ref_ctr_off >= (1ULL << PERF_UPROBE_REF_CTR_OFFSET_BITS))
+		return -EINVAL;
+
+	memset(&attr, 0, attr_sz);
+
+	type = uprobe ? determine_uprobe_perf_type()
+		      : determine_kprobe_perf_type();
+	if (type < 0) {
+		pr_warn("failed to determine %s perf type: %s\n",
+			uprobe ? "uprobe" : "kprobe",
+			libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
+		return type;
+	}
+	if (retprobe) {
+		int bit = uprobe ? determine_uprobe_retprobe_bit()
+				 : determine_kprobe_retprobe_bit();
+
+		if (bit < 0) {
+			pr_warn("failed to determine %s retprobe bit: %s\n",
+				uprobe ? "uprobe" : "kprobe",
+				libbpf_strerror_r(bit, errmsg, sizeof(errmsg)));
+			return bit;
+		}
+		attr.config |= 1 << bit;
+	}
+	attr.size = attr_sz;
+	attr.type = type;
+	attr.config |= (__u64)ref_ctr_off << PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
+	attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */
+	attr.config2 = offset;		 /* kprobe_addr or probe_offset */
+
+	/* pid filter is meaningful only for uprobes */
+	pfd = syscall(__NR_perf_event_open, &attr,
+		      pid < 0 ? -1 : pid /* pid */,
+		      pid == -1 ? 0 : -1 /* cpu */,
+		      -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
+	return pfd >= 0 ? pfd : -errno;
+}
+
+static int append_to_file(const char *file, const char *fmt, ...)
+{
+	int fd, n, err = 0;
+	va_list ap;
+
+	fd = open(file, O_WRONLY | O_APPEND | O_CLOEXEC, 0);
+	if (fd < 0)
+		return -errno;
+
+	va_start(ap, fmt);
+	n = vdprintf(fd, fmt, ap);
+	va_end(ap);
+
+	if (n < 0)
+		err = -errno;
+
+	close(fd);
+	return err;
+}
+
+#define DEBUGFS "/sys/kernel/debug/tracing"
+#define TRACEFS "/sys/kernel/tracing"
+
+static bool use_debugfs(void)
+{
+	static int has_debugfs = -1;
+
+	if (has_debugfs < 0)
+		has_debugfs = faccessat(AT_FDCWD, DEBUGFS, F_OK, AT_EACCESS) == 0;
+
+	return has_debugfs == 1;
+}
+
+static const char *tracefs_path(void)
+{
+	return use_debugfs() ? DEBUGFS : TRACEFS;
+}
+
+static const char *tracefs_kprobe_events(void)
+{
+	return use_debugfs() ? DEBUGFS"/kprobe_events" : TRACEFS"/kprobe_events";
+}
+
+static const char *tracefs_uprobe_events(void)
+{
+	return use_debugfs() ? DEBUGFS"/uprobe_events" : TRACEFS"/uprobe_events";
+}
+
+static void gen_kprobe_legacy_event_name(char *buf, size_t buf_sz,
+					 const char *kfunc_name, size_t offset)
+{
+	static int index = 0;
+
+	snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx_%d", getpid(), kfunc_name, offset,
+		 __sync_fetch_and_add(&index, 1));
+}
+
+static int add_kprobe_event_legacy(const char *probe_name, bool retprobe,
+				   const char *kfunc_name, size_t offset)
+{
+	return append_to_file(tracefs_kprobe_events(), "%c:%s/%s %s+0x%zx",
+			      retprobe ? 'r' : 'p',
+			      retprobe ? "kretprobes" : "kprobes",
+			      probe_name, kfunc_name, offset);
+}
+
+static int remove_kprobe_event_legacy(const char *probe_name, bool retprobe)
+{
+	return append_to_file(tracefs_kprobe_events(), "-:%s/%s",
+			      retprobe ? "kretprobes" : "kprobes", probe_name);
+}
+
+static int determine_kprobe_perf_type_legacy(const char *probe_name, bool retprobe)
+{
+	char file[256];
+
+	snprintf(file, sizeof(file), "%s/events/%s/%s/id",
+		 tracefs_path(), retprobe ? "kretprobes" : "kprobes", probe_name);
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int perf_event_kprobe_open_legacy(const char *probe_name, bool retprobe,
+					 const char *kfunc_name, size_t offset, int pid)
+{
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_event_attr attr;
+	char errmsg[STRERR_BUFSIZE];
+	int type, pfd, err;
+
+	err = add_kprobe_event_legacy(probe_name, retprobe, kfunc_name, offset);
+	if (err < 0) {
+		pr_warn("failed to add legacy kprobe event for '%s+0x%zx': %s\n",
+			kfunc_name, offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return err;
+	}
+	type = determine_kprobe_perf_type_legacy(probe_name, retprobe);
+	if (type < 0) {
+		err = type;
+		pr_warn("failed to determine legacy kprobe event id for '%s+0x%zx': %s\n",
+			kfunc_name, offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_clean_legacy;
+	}
+
+	memset(&attr, 0, attr_sz);
+	attr.size = attr_sz;
+	attr.config = type;
+	attr.type = PERF_TYPE_TRACEPOINT;
+
+	pfd = syscall(__NR_perf_event_open, &attr,
+		      pid < 0 ? -1 : pid, /* pid */
+		      pid == -1 ? 0 : -1, /* cpu */
+		      -1 /* group_fd */,  PERF_FLAG_FD_CLOEXEC);
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("legacy kprobe perf_event_open() failed: %s\n",
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_clean_legacy;
+	}
+	return pfd;
+
+err_clean_legacy:
+	/* Clear the newly added legacy kprobe_event */
+	remove_kprobe_event_legacy(probe_name, retprobe);
+	return err;
+}
+
+static const char *arch_specific_syscall_pfx(void)
+{
+#if defined(__x86_64__)
+	return "x64";
+#elif defined(__i386__)
+	return "ia32";
+#elif defined(__s390x__)
+	return "s390x";
+#elif defined(__s390__)
+	return "s390";
+#elif defined(__arm__)
+	return "arm";
+#elif defined(__aarch64__)
+	return "arm64";
+#elif defined(__mips__)
+	return "mips";
+#elif defined(__riscv)
+	return "riscv";
+#elif defined(__powerpc__)
+	return "powerpc";
+#elif defined(__powerpc64__)
+	return "powerpc64";
+#else
+	return NULL;
+#endif
+}
+
+static int probe_kern_syscall_wrapper(void)
+{
+	char syscall_name[64];
+	const char *ksys_pfx;
+
+	ksys_pfx = arch_specific_syscall_pfx();
+	if (!ksys_pfx)
+		return 0;
+
+	snprintf(syscall_name, sizeof(syscall_name), "__%s_sys_bpf", ksys_pfx);
+
+	if (determine_kprobe_perf_type() >= 0) {
+		int pfd;
+
+		pfd = perf_event_open_probe(false, false, syscall_name, 0, getpid(), 0);
+		if (pfd >= 0)
+			close(pfd);
+
+		return pfd >= 0 ? 1 : 0;
+	} else { /* legacy mode */
+		char probe_name[128];
+
+		gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name), syscall_name, 0);
+		if (add_kprobe_event_legacy(probe_name, false, syscall_name, 0) < 0)
+			return 0;
+
+		(void)remove_kprobe_event_legacy(probe_name, false);
+		return 1;
+	}
+}
+
+struct bpf_link *
+bpf_program__attach_kprobe_opts(const struct bpf_program *prog,
+				const char *func_name,
+				const struct bpf_kprobe_opts *opts)
+{
+	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
+	char errmsg[STRERR_BUFSIZE];
+	char *legacy_probe = NULL;
+	struct bpf_link *link;
+	size_t offset;
+	bool retprobe, legacy;
+	int pfd, err;
+
+	if (!OPTS_VALID(opts, bpf_kprobe_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	retprobe = OPTS_GET(opts, retprobe, false);
+	offset = OPTS_GET(opts, offset, 0);
+	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+
+	legacy = determine_kprobe_perf_type() < 0;
+	if (!legacy) {
+		pfd = perf_event_open_probe(false /* uprobe */, retprobe,
+					    func_name, offset,
+					    -1 /* pid */, 0 /* ref_ctr_off */);
+	} else {
+		char probe_name[256];
+
+		gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name),
+					     func_name, offset);
+
+		legacy_probe = strdup(probe_name);
+		if (!legacy_probe)
+			return libbpf_err_ptr(-ENOMEM);
+
+		pfd = perf_event_kprobe_open_legacy(legacy_probe, retprobe, func_name,
+						    offset, -1 /* pid */);
+	}
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("prog '%s': failed to create %s '%s+0x%zx' perf event: %s\n",
+			prog->name, retprobe ? "kretprobe" : "kprobe",
+			func_name, offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_out;
+	}
+	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
+	err = libbpf_get_error(link);
+	if (err) {
+		close(pfd);
+		pr_warn("prog '%s': failed to attach to %s '%s+0x%zx': %s\n",
+			prog->name, retprobe ? "kretprobe" : "kprobe",
+			func_name, offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_clean_legacy;
+	}
+	if (legacy) {
+		struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
+
+		perf_link->legacy_probe_name = legacy_probe;
+		perf_link->legacy_is_kprobe = true;
+		perf_link->legacy_is_retprobe = retprobe;
+	}
+
+	return link;
+
+err_clean_legacy:
+	if (legacy)
+		remove_kprobe_event_legacy(legacy_probe, retprobe);
+err_out:
+	free(legacy_probe);
+	return libbpf_err_ptr(err);
+}
+
+struct bpf_link *bpf_program__attach_kprobe(const struct bpf_program *prog,
+					    bool retprobe,
+					    const char *func_name)
+{
+	DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts,
+		.retprobe = retprobe,
+	);
+
+	return bpf_program__attach_kprobe_opts(prog, func_name, &opts);
+}
+
+struct bpf_link *bpf_program__attach_ksyscall(const struct bpf_program *prog,
+					      const char *syscall_name,
+					      const struct bpf_ksyscall_opts *opts)
+{
+	LIBBPF_OPTS(bpf_kprobe_opts, kprobe_opts);
+	char func_name[128];
+
+	if (!OPTS_VALID(opts, bpf_ksyscall_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	if (kernel_supports(prog->obj, FEAT_SYSCALL_WRAPPER)) {
+		/* arch_specific_syscall_pfx() should never return NULL here
+		 * because it is guarded by kernel_supports(). However, since
+		 * compiler does not know that we have an explicit conditional
+		 * as well.
+		 */
+		snprintf(func_name, sizeof(func_name), "__%s_sys_%s",
+			 arch_specific_syscall_pfx() ? : "", syscall_name);
+	} else {
+		snprintf(func_name, sizeof(func_name), "__se_sys_%s", syscall_name);
+	}
+
+	kprobe_opts.retprobe = OPTS_GET(opts, retprobe, false);
+	kprobe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+
+	return bpf_program__attach_kprobe_opts(prog, func_name, &kprobe_opts);
+}
+
+/* Adapted from perf/util/string.c */
+static bool glob_match(const char *str, const char *pat)
+{
+	while (*str && *pat && *pat != '*') {
+		if (*pat == '?') {      /* Matches any single character */
+			str++;
+			pat++;
+			continue;
+		}
+		if (*str != *pat)
+			return false;
+		str++;
+		pat++;
+	}
+	/* Check wild card */
+	if (*pat == '*') {
+		while (*pat == '*')
+			pat++;
+		if (!*pat) /* Tail wild card matches all */
+			return true;
+		while (*str)
+			if (glob_match(str++, pat))
+				return true;
+	}
+	return !*str && !*pat;
+}
+
+struct kprobe_multi_resolve {
+	const char *pattern;
+	unsigned long *addrs;
+	size_t cap;
+	size_t cnt;
+};
+
+static int
+resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type,
+			const char *sym_name, void *ctx)
+{
+	struct kprobe_multi_resolve *res = ctx;
+	int err;
+
+	if (!glob_match(sym_name, res->pattern))
+		return 0;
+
+	err = libbpf_ensure_mem((void **) &res->addrs, &res->cap, sizeof(unsigned long),
+				res->cnt + 1);
+	if (err)
+		return err;
+
+	res->addrs[res->cnt++] = (unsigned long) sym_addr;
+	return 0;
+}
+
+struct bpf_link *
+bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
+				      const char *pattern,
+				      const struct bpf_kprobe_multi_opts *opts)
+{
+	LIBBPF_OPTS(bpf_link_create_opts, lopts);
+	struct kprobe_multi_resolve res = {
+		.pattern = pattern,
+	};
+	struct bpf_link *link = NULL;
+	char errmsg[STRERR_BUFSIZE];
+	const unsigned long *addrs;
+	int err, link_fd, prog_fd;
+	const __u64 *cookies;
+	const char **syms;
+	bool retprobe;
+	size_t cnt;
+
+	if (!OPTS_VALID(opts, bpf_kprobe_multi_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	syms    = OPTS_GET(opts, syms, false);
+	addrs   = OPTS_GET(opts, addrs, false);
+	cnt     = OPTS_GET(opts, cnt, false);
+	cookies = OPTS_GET(opts, cookies, false);
+
+	if (!pattern && !addrs && !syms)
+		return libbpf_err_ptr(-EINVAL);
+	if (pattern && (addrs || syms || cookies || cnt))
+		return libbpf_err_ptr(-EINVAL);
+	if (!pattern && !cnt)
+		return libbpf_err_ptr(-EINVAL);
+	if (addrs && syms)
+		return libbpf_err_ptr(-EINVAL);
+
+	if (pattern) {
+		err = libbpf_kallsyms_parse(resolve_kprobe_multi_cb, &res);
+		if (err)
+			goto error;
+		if (!res.cnt) {
+			err = -ENOENT;
+			goto error;
+		}
+		addrs = res.addrs;
+		cnt = res.cnt;
+	}
+
+	retprobe = OPTS_GET(opts, retprobe, false);
+
+	lopts.kprobe_multi.syms = syms;
+	lopts.kprobe_multi.addrs = addrs;
+	lopts.kprobe_multi.cookies = cookies;
+	lopts.kprobe_multi.cnt = cnt;
+	lopts.kprobe_multi.flags = retprobe ? BPF_F_KPROBE_MULTI_RETURN : 0;
+
+	link = calloc(1, sizeof(*link));
+	if (!link) {
+		err = -ENOMEM;
+		goto error;
+	}
+	link->detach = &bpf_link__detach_fd;
+
+	prog_fd = bpf_program__fd(prog);
+	link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_KPROBE_MULTI, &lopts);
+	if (link_fd < 0) {
+		err = -errno;
+		pr_warn("prog '%s': failed to attach: %s\n",
+			prog->name, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto error;
+	}
+	link->fd = link_fd;
+	free(res.addrs);
+	return link;
+
+error:
+	free(link);
+	free(res.addrs);
+	return libbpf_err_ptr(err);
+}
+
+static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts);
+	unsigned long offset = 0;
+	const char *func_name;
+	char *func;
+	int n;
+
+	*link = NULL;
+
+	/* no auto-attach for SEC("kprobe") and SEC("kretprobe") */
+	if (strcmp(prog->sec_name, "kprobe") == 0 || strcmp(prog->sec_name, "kretprobe") == 0)
+		return 0;
+
+	opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe/");
+	if (opts.retprobe)
+		func_name = prog->sec_name + sizeof("kretprobe/") - 1;
+	else
+		func_name = prog->sec_name + sizeof("kprobe/") - 1;
+
+	n = sscanf(func_name, "%m[a-zA-Z0-9_.]+%li", &func, &offset);
+	if (n < 1) {
+		pr_warn("kprobe name is invalid: %s\n", func_name);
+		return -EINVAL;
+	}
+	if (opts.retprobe && offset != 0) {
+		free(func);
+		pr_warn("kretprobes do not support offset specification\n");
+		return -EINVAL;
+	}
+
+	opts.offset = offset;
+	*link = bpf_program__attach_kprobe_opts(prog, func, &opts);
+	free(func);
+	return libbpf_get_error(*link);
+}
+
+static int attach_ksyscall(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	LIBBPF_OPTS(bpf_ksyscall_opts, opts);
+	const char *syscall_name;
+
+	*link = NULL;
+
+	/* no auto-attach for SEC("ksyscall") and SEC("kretsyscall") */
+	if (strcmp(prog->sec_name, "ksyscall") == 0 || strcmp(prog->sec_name, "kretsyscall") == 0)
+		return 0;
+
+	opts.retprobe = str_has_pfx(prog->sec_name, "kretsyscall/");
+	if (opts.retprobe)
+		syscall_name = prog->sec_name + sizeof("kretsyscall/") - 1;
+	else
+		syscall_name = prog->sec_name + sizeof("ksyscall/") - 1;
+
+	*link = bpf_program__attach_ksyscall(prog, syscall_name, &opts);
+	return *link ? 0 : -errno;
+}
+
+static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
+	const char *spec;
+	char *pattern;
+	int n;
+
+	*link = NULL;
+
+	/* no auto-attach for SEC("kprobe.multi") and SEC("kretprobe.multi") */
+	if (strcmp(prog->sec_name, "kprobe.multi") == 0 ||
+	    strcmp(prog->sec_name, "kretprobe.multi") == 0)
+		return 0;
+
+	opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe.multi/");
+	if (opts.retprobe)
+		spec = prog->sec_name + sizeof("kretprobe.multi/") - 1;
+	else
+		spec = prog->sec_name + sizeof("kprobe.multi/") - 1;
+
+	n = sscanf(spec, "%m[a-zA-Z0-9_.*?]", &pattern);
+	if (n < 1) {
+		pr_warn("kprobe multi pattern is invalid: %s\n", pattern);
+		return -EINVAL;
+	}
+
+	*link = bpf_program__attach_kprobe_multi_opts(prog, pattern, &opts);
+	free(pattern);
+	return libbpf_get_error(*link);
+}
+
+static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
+					 const char *binary_path, uint64_t offset)
+{
+	int i;
+
+	snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx", getpid(), binary_path, (size_t)offset);
+
+	/* sanitize binary_path in the probe name */
+	for (i = 0; buf[i]; i++) {
+		if (!isalnum(buf[i]))
+			buf[i] = '_';
+	}
+}
+
+static inline int add_uprobe_event_legacy(const char *probe_name, bool retprobe,
+					  const char *binary_path, size_t offset)
+{
+	return append_to_file(tracefs_uprobe_events(), "%c:%s/%s %s:0x%zx",
+			      retprobe ? 'r' : 'p',
+			      retprobe ? "uretprobes" : "uprobes",
+			      probe_name, binary_path, offset);
+}
+
+static inline int remove_uprobe_event_legacy(const char *probe_name, bool retprobe)
+{
+	return append_to_file(tracefs_uprobe_events(), "-:%s/%s",
+			      retprobe ? "uretprobes" : "uprobes", probe_name);
+}
+
+static int determine_uprobe_perf_type_legacy(const char *probe_name, bool retprobe)
+{
+	char file[512];
+
+	snprintf(file, sizeof(file), "%s/events/%s/%s/id",
+		 tracefs_path(), retprobe ? "uretprobes" : "uprobes", probe_name);
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
+					 const char *binary_path, size_t offset, int pid)
+{
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_event_attr attr;
+	int type, pfd, err;
+
+	err = add_uprobe_event_legacy(probe_name, retprobe, binary_path, offset);
+	if (err < 0) {
+		pr_warn("failed to add legacy uprobe event for %s:0x%zx: %d\n",
+			binary_path, (size_t)offset, err);
+		return err;
+	}
+	type = determine_uprobe_perf_type_legacy(probe_name, retprobe);
+	if (type < 0) {
+		err = type;
+		pr_warn("failed to determine legacy uprobe event id for %s:0x%zx: %d\n",
+			binary_path, offset, err);
+		goto err_clean_legacy;
+	}
+
+	memset(&attr, 0, attr_sz);
+	attr.size = attr_sz;
+	attr.config = type;
+	attr.type = PERF_TYPE_TRACEPOINT;
+
+	pfd = syscall(__NR_perf_event_open, &attr,
+		      pid < 0 ? -1 : pid, /* pid */
+		      pid == -1 ? 0 : -1, /* cpu */
+		      -1 /* group_fd */,  PERF_FLAG_FD_CLOEXEC);
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("legacy uprobe perf_event_open() failed: %d\n", err);
+		goto err_clean_legacy;
+	}
+	return pfd;
+
+err_clean_legacy:
+	/* Clear the newly added legacy uprobe_event */
+	remove_uprobe_event_legacy(probe_name, retprobe);
+	return err;
+}
+
+/* Return next ELF section of sh_type after scn, or first of that type if scn is NULL. */
+static Elf_Scn *elf_find_next_scn_by_type(Elf *elf, int sh_type, Elf_Scn *scn)
+{
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		GElf_Shdr sh;
+
+		if (!gelf_getshdr(scn, &sh))
+			continue;
+		if (sh.sh_type == sh_type)
+			return scn;
+	}
+	return NULL;
+}
+
+/* Find offset of function name in object specified by path.  "name" matches
+ * symbol name or name@@LIB for library functions.
+ */
+static long elf_find_func_offset(const char *binary_path, const char *name)
+{
+	int fd, i, sh_types[2] = { SHT_DYNSYM, SHT_SYMTAB };
+	bool is_shared_lib, is_name_qualified;
+	char errmsg[STRERR_BUFSIZE];
+	long ret = -ENOENT;
+	size_t name_len;
+	GElf_Ehdr ehdr;
+	Elf *elf;
+
+	fd = open(binary_path, O_RDONLY | O_CLOEXEC);
+	if (fd < 0) {
+		ret = -errno;
+		pr_warn("failed to open %s: %s\n", binary_path,
+			libbpf_strerror_r(ret, errmsg, sizeof(errmsg)));
+		return ret;
+	}
+	elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+	if (!elf) {
+		pr_warn("elf: could not read elf from %s: %s\n", binary_path, elf_errmsg(-1));
+		close(fd);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	if (!gelf_getehdr(elf, &ehdr)) {
+		pr_warn("elf: failed to get ehdr from %s: %s\n", binary_path, elf_errmsg(-1));
+		ret = -LIBBPF_ERRNO__FORMAT;
+		goto out;
+	}
+	/* for shared lib case, we do not need to calculate relative offset */
+	is_shared_lib = ehdr.e_type == ET_DYN;
+
+	name_len = strlen(name);
+	/* Does name specify "@@LIB"? */
+	is_name_qualified = strstr(name, "@@") != NULL;
+
+	/* Search SHT_DYNSYM, SHT_SYMTAB for symbol.  This search order is used because if
+	 * a binary is stripped, it may only have SHT_DYNSYM, and a fully-statically
+	 * linked binary may not have SHT_DYMSYM, so absence of a section should not be
+	 * reported as a warning/error.
+	 */
+	for (i = 0; i < ARRAY_SIZE(sh_types); i++) {
+		size_t nr_syms, strtabidx, idx;
+		Elf_Data *symbols = NULL;
+		Elf_Scn *scn = NULL;
+		int last_bind = -1;
+		const char *sname;
+		GElf_Shdr sh;
+
+		scn = elf_find_next_scn_by_type(elf, sh_types[i], NULL);
+		if (!scn) {
+			pr_debug("elf: failed to find symbol table ELF sections in '%s'\n",
+				 binary_path);
+			continue;
+		}
+		if (!gelf_getshdr(scn, &sh))
+			continue;
+		strtabidx = sh.sh_link;
+		symbols = elf_getdata(scn, 0);
+		if (!symbols) {
+			pr_warn("elf: failed to get symbols for symtab section in '%s': %s\n",
+				binary_path, elf_errmsg(-1));
+			ret = -LIBBPF_ERRNO__FORMAT;
+			goto out;
+		}
+		nr_syms = symbols->d_size / sh.sh_entsize;
+
+		for (idx = 0; idx < nr_syms; idx++) {
+			int curr_bind;
+			GElf_Sym sym;
+			Elf_Scn *sym_scn;
+			GElf_Shdr sym_sh;
+
+			if (!gelf_getsym(symbols, idx, &sym))
+				continue;
+
+			if (GELF_ST_TYPE(sym.st_info) != STT_FUNC)
+				continue;
+
+			sname = elf_strptr(elf, strtabidx, sym.st_name);
+			if (!sname)
+				continue;
+
+			curr_bind = GELF_ST_BIND(sym.st_info);
+
+			/* User can specify func, func@@LIB or func@@LIB_VERSION. */
+			if (strncmp(sname, name, name_len) != 0)
+				continue;
+			/* ...but we don't want a search for "foo" to match 'foo2" also, so any
+			 * additional characters in sname should be of the form "@@LIB".
+			 */
+			if (!is_name_qualified && sname[name_len] != '\0' && sname[name_len] != '@')
+				continue;
+
+			if (ret >= 0) {
+				/* handle multiple matches */
+				if (last_bind != STB_WEAK && curr_bind != STB_WEAK) {
+					/* Only accept one non-weak bind. */
+					pr_warn("elf: ambiguous match for '%s', '%s' in '%s'\n",
+						sname, name, binary_path);
+					ret = -LIBBPF_ERRNO__FORMAT;
+					goto out;
+				} else if (curr_bind == STB_WEAK) {
+					/* already have a non-weak bind, and
+					 * this is a weak bind, so ignore.
+					 */
+					continue;
+				}
+			}
+
+			/* Transform symbol's virtual address (absolute for
+			 * binaries and relative for shared libs) into file
+			 * offset, which is what kernel is expecting for
+			 * uprobe/uretprobe attachment.
+			 * See Documentation/trace/uprobetracer.rst for more
+			 * details.
+			 * This is done by looking up symbol's containing
+			 * section's header and using it's virtual address
+			 * (sh_addr) and corresponding file offset (sh_offset)
+			 * to transform sym.st_value (virtual address) into
+			 * desired final file offset.
+			 */
+			sym_scn = elf_getscn(elf, sym.st_shndx);
+			if (!sym_scn)
+				continue;
+			if (!gelf_getshdr(sym_scn, &sym_sh))
+				continue;
+
+			ret = sym.st_value - sym_sh.sh_addr + sym_sh.sh_offset;
+			last_bind = curr_bind;
+		}
+		if (ret > 0)
+			break;
+	}
+
+	if (ret > 0) {
+		pr_debug("elf: symbol address match for '%s' in '%s': 0x%lx\n", name, binary_path,
+			 ret);
+	} else {
+		if (ret == 0) {
+			pr_warn("elf: '%s' is 0 in symtab for '%s': %s\n", name, binary_path,
+				is_shared_lib ? "should not be 0 in a shared library" :
+						"try using shared library path instead");
+			ret = -ENOENT;
+		} else {
+			pr_warn("elf: failed to find symbol '%s' in '%s'\n", name, binary_path);
+		}
+	}
+out:
+	elf_end(elf);
+	close(fd);
+	return ret;
+}
+
+static const char *arch_specific_lib_paths(void)
+{
+	/*
+	 * Based on https://packages.debian.org/sid/libc6.
+	 *
+	 * Assume that the traced program is built for the same architecture
+	 * as libbpf, which should cover the vast majority of cases.
+	 */
+#if defined(__x86_64__)
+	return "/lib/x86_64-linux-gnu";
+#elif defined(__i386__)
+	return "/lib/i386-linux-gnu";
+#elif defined(__s390x__)
+	return "/lib/s390x-linux-gnu";
+#elif defined(__s390__)
+	return "/lib/s390-linux-gnu";
+#elif defined(__arm__) && defined(__SOFTFP__)
+	return "/lib/arm-linux-gnueabi";
+#elif defined(__arm__) && !defined(__SOFTFP__)
+	return "/lib/arm-linux-gnueabihf";
+#elif defined(__aarch64__)
+	return "/lib/aarch64-linux-gnu";
+#elif defined(__mips__) && defined(__MIPSEL__) && _MIPS_SZLONG == 64
+	return "/lib/mips64el-linux-gnuabi64";
+#elif defined(__mips__) && defined(__MIPSEL__) && _MIPS_SZLONG == 32
+	return "/lib/mipsel-linux-gnu";
+#elif defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	return "/lib/powerpc64le-linux-gnu";
+#elif defined(__sparc__) && defined(__arch64__)
+	return "/lib/sparc64-linux-gnu";
+#elif defined(__riscv) && __riscv_xlen == 64
+	return "/lib/riscv64-linux-gnu";
+#else
+	return NULL;
+#endif
+}
+
+/* Get full path to program/shared library. */
+static int resolve_full_path(const char *file, char *result, size_t result_sz)
+{
+	const char *search_paths[3] = {};
+	int i, perm;
+
+	if (str_has_sfx(file, ".so") || strstr(file, ".so.")) {
+		search_paths[0] = getenv("LD_LIBRARY_PATH");
+		search_paths[1] = "/usr/lib64:/usr/lib";
+		search_paths[2] = arch_specific_lib_paths();
+		perm = R_OK;
+	} else {
+		search_paths[0] = getenv("PATH");
+		search_paths[1] = "/usr/bin:/usr/sbin";
+		perm = R_OK | X_OK;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(search_paths); i++) {
+		const char *s;
+
+		if (!search_paths[i])
+			continue;
+		for (s = search_paths[i]; s != NULL; s = strchr(s, ':')) {
+			char *next_path;
+			int seg_len;
+
+			if (s[0] == ':')
+				s++;
+			next_path = strchr(s, ':');
+			seg_len = next_path ? next_path - s : strlen(s);
+			if (!seg_len)
+				continue;
+			snprintf(result, result_sz, "%.*s/%s", seg_len, s, file);
+			/* ensure it has required permissions */
+			if (faccessat(AT_FDCWD, result, perm, AT_EACCESS) < 0)
+				continue;
+			pr_debug("resolved '%s' to '%s'\n", file, result);
+			return 0;
+		}
+	}
+	return -ENOENT;
+}
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
+				const char *binary_path, size_t func_offset,
+				const struct bpf_uprobe_opts *opts)
+{
+	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
+	char errmsg[STRERR_BUFSIZE], *legacy_probe = NULL;
+	char full_binary_path[PATH_MAX];
+	struct bpf_link *link;
+	size_t ref_ctr_off;
+	int pfd, err;
+	bool retprobe, legacy;
+	const char *func_name;
+
+	if (!OPTS_VALID(opts, bpf_uprobe_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	retprobe = OPTS_GET(opts, retprobe, false);
+	ref_ctr_off = OPTS_GET(opts, ref_ctr_offset, 0);
+	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+
+	if (!binary_path)
+		return libbpf_err_ptr(-EINVAL);
+
+	if (!strchr(binary_path, '/')) {
+		err = resolve_full_path(binary_path, full_binary_path,
+					sizeof(full_binary_path));
+		if (err) {
+			pr_warn("prog '%s': failed to resolve full path for '%s': %d\n",
+				prog->name, binary_path, err);
+			return libbpf_err_ptr(err);
+		}
+		binary_path = full_binary_path;
+	}
+	func_name = OPTS_GET(opts, func_name, NULL);
+	if (func_name) {
+		long sym_off;
+
+		sym_off = elf_find_func_offset(binary_path, func_name);
+		if (sym_off < 0)
+			return libbpf_err_ptr(sym_off);
+		func_offset += sym_off;
+	}
+
+	legacy = determine_uprobe_perf_type() < 0;
+	if (!legacy) {
+		pfd = perf_event_open_probe(true /* uprobe */, retprobe, binary_path,
+					    func_offset, pid, ref_ctr_off);
+	} else {
+		char probe_name[PATH_MAX + 64];
+
+		if (ref_ctr_off)
+			return libbpf_err_ptr(-EINVAL);
+
+		gen_uprobe_legacy_event_name(probe_name, sizeof(probe_name),
+					     binary_path, func_offset);
+
+		legacy_probe = strdup(probe_name);
+		if (!legacy_probe)
+			return libbpf_err_ptr(-ENOMEM);
+
+		pfd = perf_event_uprobe_open_legacy(legacy_probe, retprobe,
+						    binary_path, func_offset, pid);
+	}
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("prog '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
+			prog->name, retprobe ? "uretprobe" : "uprobe",
+			binary_path, func_offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_out;
+	}
+
+	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
+	err = libbpf_get_error(link);
+	if (err) {
+		close(pfd);
+		pr_warn("prog '%s': failed to attach to %s '%s:0x%zx': %s\n",
+			prog->name, retprobe ? "uretprobe" : "uprobe",
+			binary_path, func_offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_clean_legacy;
+	}
+	if (legacy) {
+		struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
+
+		perf_link->legacy_probe_name = legacy_probe;
+		perf_link->legacy_is_kprobe = false;
+		perf_link->legacy_is_retprobe = retprobe;
+	}
+	return link;
+
+err_clean_legacy:
+	if (legacy)
+		remove_uprobe_event_legacy(legacy_probe, retprobe);
+err_out:
+	free(legacy_probe);
+	return libbpf_err_ptr(err);
+}
+
+/* Format of u[ret]probe section definition supporting auto-attach:
+ * u[ret]probe/binary:function[+offset]
+ *
+ * binary can be an absolute/relative path or a filename; the latter is resolved to a
+ * full binary path via bpf_program__attach_uprobe_opts.
+ *
+ * Specifying uprobe+ ensures we carry out strict matching; either "uprobe" must be
+ * specified (and auto-attach is not possible) or the above format is specified for
+ * auto-attach.
+ */
+static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts);
+	char *probe_type = NULL, *binary_path = NULL, *func_name = NULL;
+	int n, ret = -EINVAL;
+	long offset = 0;
+
+	*link = NULL;
+
+	n = sscanf(prog->sec_name, "%m[^/]/%m[^:]:%m[a-zA-Z0-9_.]+%li",
+		   &probe_type, &binary_path, &func_name, &offset);
+	switch (n) {
+	case 1:
+		/* handle SEC("u[ret]probe") - format is valid, but auto-attach is impossible. */
+		ret = 0;
+		break;
+	case 2:
+		pr_warn("prog '%s': section '%s' missing ':function[+offset]' specification\n",
+			prog->name, prog->sec_name);
+		break;
+	case 3:
+	case 4:
+		opts.retprobe = strcmp(probe_type, "uretprobe") == 0 ||
+				strcmp(probe_type, "uretprobe.s") == 0;
+		if (opts.retprobe && offset != 0) {
+			pr_warn("prog '%s': uretprobes do not support offset specification\n",
+				prog->name);
+			break;
+		}
+		opts.func_name = func_name;
+		*link = bpf_program__attach_uprobe_opts(prog, -1, binary_path, offset, &opts);
+		ret = libbpf_get_error(*link);
+		break;
+	default:
+		pr_warn("prog '%s': invalid format of section definition '%s'\n", prog->name,
+			prog->sec_name);
+		break;
+	}
+	free(probe_type);
+	free(binary_path);
+	free(func_name);
+
+	return ret;
+}
+
+struct bpf_link *bpf_program__attach_uprobe(const struct bpf_program *prog,
+					    bool retprobe, pid_t pid,
+					    const char *binary_path,
+					    size_t func_offset)
+{
+	DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts, .retprobe = retprobe);
+
+	return bpf_program__attach_uprobe_opts(prog, pid, binary_path, func_offset, &opts);
+}
+
+struct bpf_link *bpf_program__attach_usdt(const struct bpf_program *prog,
+					  pid_t pid, const char *binary_path,
+					  const char *usdt_provider, const char *usdt_name,
+					  const struct bpf_usdt_opts *opts)
+{
+	char resolved_path[512];
+	struct bpf_object *obj = prog->obj;
+	struct bpf_link *link;
+	__u64 usdt_cookie;
+	int err;
+
+	if (!OPTS_VALID(opts, bpf_uprobe_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	if (bpf_program__fd(prog) < 0) {
+		pr_warn("prog '%s': can't attach BPF program w/o FD (did you load it?)\n",
+			prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	if (!binary_path)
+		return libbpf_err_ptr(-EINVAL);
+
+	if (!strchr(binary_path, '/')) {
+		err = resolve_full_path(binary_path, resolved_path, sizeof(resolved_path));
+		if (err) {
+			pr_warn("prog '%s': failed to resolve full path for '%s': %d\n",
+				prog->name, binary_path, err);
+			return libbpf_err_ptr(err);
+		}
+		binary_path = resolved_path;
+	}
+
+	/* USDT manager is instantiated lazily on first USDT attach. It will
+	 * be destroyed together with BPF object in bpf_object__close().
+	 */
+	if (IS_ERR(obj->usdt_man))
+		return libbpf_ptr(obj->usdt_man);
+	if (!obj->usdt_man) {
+		obj->usdt_man = usdt_manager_new(obj);
+		if (IS_ERR(obj->usdt_man))
+			return libbpf_ptr(obj->usdt_man);
+	}
+
+	usdt_cookie = OPTS_GET(opts, usdt_cookie, 0);
+	link = usdt_manager_attach_usdt(obj->usdt_man, prog, pid, binary_path,
+					usdt_provider, usdt_name, usdt_cookie);
+	err = libbpf_get_error(link);
+	if (err)
+		return libbpf_err_ptr(err);
+	return link;
+}
+
+static int attach_usdt(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	char *path = NULL, *provider = NULL, *name = NULL;
+	const char *sec_name;
+	int n, err;
+
+	sec_name = bpf_program__section_name(prog);
+	if (strcmp(sec_name, "usdt") == 0) {
+		/* no auto-attach for just SEC("usdt") */
+		*link = NULL;
+		return 0;
+	}
+
+	n = sscanf(sec_name, "usdt/%m[^:]:%m[^:]:%m[^:]", &path, &provider, &name);
+	if (n != 3) {
+		pr_warn("invalid section '%s', expected SEC(\"usdt/<path>:<provider>:<name>\")\n",
+			sec_name);
+		err = -EINVAL;
+	} else {
+		*link = bpf_program__attach_usdt(prog, -1 /* any process */, path,
+						 provider, name, NULL);
+		err = libbpf_get_error(*link);
+	}
+	free(path);
+	free(provider);
+	free(name);
+	return err;
+}
+
+static int determine_tracepoint_id(const char *tp_category,
+				   const char *tp_name)
+{
+	char file[PATH_MAX];
+	int ret;
+
+	ret = snprintf(file, sizeof(file), "%s/events/%s/%s/id",
+		       tracefs_path(), tp_category, tp_name);
+	if (ret < 0)
+		return -errno;
+	if (ret >= sizeof(file)) {
+		pr_debug("tracepoint %s/%s path is too long\n",
+			 tp_category, tp_name);
+		return -E2BIG;
+	}
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int perf_event_open_tracepoint(const char *tp_category,
+				      const char *tp_name)
+{
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_event_attr attr;
+	char errmsg[STRERR_BUFSIZE];
+	int tp_id, pfd, err;
+
+	tp_id = determine_tracepoint_id(tp_category, tp_name);
+	if (tp_id < 0) {
+		pr_warn("failed to determine tracepoint '%s/%s' perf event ID: %s\n",
+			tp_category, tp_name,
+			libbpf_strerror_r(tp_id, errmsg, sizeof(errmsg)));
+		return tp_id;
+	}
+
+	memset(&attr, 0, attr_sz);
+	attr.type = PERF_TYPE_TRACEPOINT;
+	attr.size = attr_sz;
+	attr.config = tp_id;
+
+	pfd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, 0 /* cpu */,
+		      -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("tracepoint '%s/%s' perf_event_open() failed: %s\n",
+			tp_category, tp_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return err;
+	}
+	return pfd;
+}
+
+struct bpf_link *bpf_program__attach_tracepoint_opts(const struct bpf_program *prog,
+						     const char *tp_category,
+						     const char *tp_name,
+						     const struct bpf_tracepoint_opts *opts)
+{
+	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int pfd, err;
+
+	if (!OPTS_VALID(opts, bpf_tracepoint_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+
+	pfd = perf_event_open_tracepoint(tp_category, tp_name);
+	if (pfd < 0) {
+		pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
+			prog->name, tp_category, tp_name,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(pfd);
+	}
+	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
+	err = libbpf_get_error(link);
+	if (err) {
+		close(pfd);
+		pr_warn("prog '%s': failed to attach to tracepoint '%s/%s': %s\n",
+			prog->name, tp_category, tp_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(err);
+	}
+	return link;
+}
+
+struct bpf_link *bpf_program__attach_tracepoint(const struct bpf_program *prog,
+						const char *tp_category,
+						const char *tp_name)
+{
+	return bpf_program__attach_tracepoint_opts(prog, tp_category, tp_name, NULL);
+}
+
+static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	char *sec_name, *tp_cat, *tp_name;
+
+	*link = NULL;
+
+	/* no auto-attach for SEC("tp") or SEC("tracepoint") */
+	if (strcmp(prog->sec_name, "tp") == 0 || strcmp(prog->sec_name, "tracepoint") == 0)
+		return 0;
+
+	sec_name = strdup(prog->sec_name);
+	if (!sec_name)
+		return -ENOMEM;
+
+	/* extract "tp/<category>/<name>" or "tracepoint/<category>/<name>" */
+	if (str_has_pfx(prog->sec_name, "tp/"))
+		tp_cat = sec_name + sizeof("tp/") - 1;
+	else
+		tp_cat = sec_name + sizeof("tracepoint/") - 1;
+	tp_name = strchr(tp_cat, '/');
+	if (!tp_name) {
+		free(sec_name);
+		return -EINVAL;
+	}
+	*tp_name = '\0';
+	tp_name++;
+
+	*link = bpf_program__attach_tracepoint(prog, tp_cat, tp_name);
+	free(sec_name);
+	return libbpf_get_error(*link);
+}
+
+struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,
+						    const char *tp_name)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int prog_fd, pfd;
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->detach = &bpf_link__detach_fd;
+
+	pfd = bpf_raw_tracepoint_open(tp_name, prog_fd);
+	if (pfd < 0) {
+		pfd = -errno;
+		free(link);
+		pr_warn("prog '%s': failed to attach to raw tracepoint '%s': %s\n",
+			prog->name, tp_name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(pfd);
+	}
+	link->fd = pfd;
+	return link;
+}
+
+static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	static const char *const prefixes[] = {
+		"raw_tp",
+		"raw_tracepoint",
+		"raw_tp.w",
+		"raw_tracepoint.w",
+	};
+	size_t i;
+	const char *tp_name = NULL;
+
+	*link = NULL;
+
+	for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
+		size_t pfx_len;
+
+		if (!str_has_pfx(prog->sec_name, prefixes[i]))
+			continue;
+
+		pfx_len = strlen(prefixes[i]);
+		/* no auto-attach case of, e.g., SEC("raw_tp") */
+		if (prog->sec_name[pfx_len] == '\0')
+			return 0;
+
+		if (prog->sec_name[pfx_len] != '/')
+			continue;
+
+		tp_name = prog->sec_name + pfx_len + 1;
+		break;
+	}
+
+	if (!tp_name) {
+		pr_warn("prog '%s': invalid section name '%s'\n",
+			prog->name, prog->sec_name);
+		return -EINVAL;
+	}
+
+	*link = bpf_program__attach_raw_tracepoint(prog, tp_name);
+	return libbpf_get_error(*link);
+}
+
+/* Common logic for all BPF program types that attach to a btf_id */
+static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *prog,
+						   const struct bpf_trace_opts *opts)
+{
+	LIBBPF_OPTS(bpf_link_create_opts, link_opts);
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int prog_fd, pfd;
+
+	if (!OPTS_VALID(opts, bpf_trace_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->detach = &bpf_link__detach_fd;
+
+	/* libbpf is smart enough to redirect to BPF_RAW_TRACEPOINT_OPEN on old kernels */
+	link_opts.tracing.cookie = OPTS_GET(opts, cookie, 0);
+	pfd = bpf_link_create(prog_fd, 0, bpf_program__expected_attach_type(prog), &link_opts);
+	if (pfd < 0) {
+		pfd = -errno;
+		free(link);
+		pr_warn("prog '%s': failed to attach: %s\n",
+			prog->name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(pfd);
+	}
+	link->fd = pfd;
+	return link;
+}
+
+struct bpf_link *bpf_program__attach_trace(const struct bpf_program *prog)
+{
+	return bpf_program__attach_btf_id(prog, NULL);
+}
+
+struct bpf_link *bpf_program__attach_trace_opts(const struct bpf_program *prog,
+						const struct bpf_trace_opts *opts)
+{
+	return bpf_program__attach_btf_id(prog, opts);
+}
+
+struct bpf_link *bpf_program__attach_lsm(const struct bpf_program *prog)
+{
+	return bpf_program__attach_btf_id(prog, NULL);
+}
+
+static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	*link = bpf_program__attach_trace(prog);
+	return libbpf_get_error(*link);
+}
+
+static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	*link = bpf_program__attach_lsm(prog);
+	return libbpf_get_error(*link);
+}
+
+static struct bpf_link *
+bpf_program__attach_fd(const struct bpf_program *prog, int target_fd, int btf_id,
+		       const char *target_name)
+{
+	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts,
+			    .target_btf_id = btf_id);
+	enum bpf_attach_type attach_type;
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int prog_fd, link_fd;
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->detach = &bpf_link__detach_fd;
+
+	attach_type = bpf_program__expected_attach_type(prog);
+	link_fd = bpf_link_create(prog_fd, target_fd, attach_type, &opts);
+	if (link_fd < 0) {
+		link_fd = -errno;
+		free(link);
+		pr_warn("prog '%s': failed to attach to %s: %s\n",
+			prog->name, target_name,
+			libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(link_fd);
+	}
+	link->fd = link_fd;
+	return link;
+}
+
+struct bpf_link *
+bpf_program__attach_cgroup(const struct bpf_program *prog, int cgroup_fd)
+{
+	return bpf_program__attach_fd(prog, cgroup_fd, 0, "cgroup");
+}
+
+struct bpf_link *
+bpf_program__attach_netns(const struct bpf_program *prog, int netns_fd)
+{
+	return bpf_program__attach_fd(prog, netns_fd, 0, "netns");
+}
+
+struct bpf_link *bpf_program__attach_xdp(const struct bpf_program *prog, int ifindex)
+{
+	/* target_fd/target_ifindex use the same field in LINK_CREATE */
+	return bpf_program__attach_fd(prog, ifindex, 0, "xdp");
+}
+
+struct bpf_link *bpf_program__attach_freplace(const struct bpf_program *prog,
+					      int target_fd,
+					      const char *attach_func_name)
+{
+	int btf_id;
+
+	if (!!target_fd != !!attach_func_name) {
+		pr_warn("prog '%s': supply none or both of target_fd and attach_func_name\n",
+			prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	if (prog->type != BPF_PROG_TYPE_EXT) {
+		pr_warn("prog '%s': only BPF_PROG_TYPE_EXT can attach as freplace",
+			prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	if (target_fd) {
+		btf_id = libbpf_find_prog_btf_id(attach_func_name, target_fd);
+		if (btf_id < 0)
+			return libbpf_err_ptr(btf_id);
+
+		return bpf_program__attach_fd(prog, target_fd, btf_id, "freplace");
+	} else {
+		/* no target, so use raw_tracepoint_open for compatibility
+		 * with old kernels
+		 */
+		return bpf_program__attach_trace(prog);
+	}
+}
+
+struct bpf_link *
+bpf_program__attach_iter(const struct bpf_program *prog,
+			 const struct bpf_iter_attach_opts *opts)
+{
+	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int prog_fd, link_fd;
+	__u32 target_fd = 0;
+
+	if (!OPTS_VALID(opts, bpf_iter_attach_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	link_create_opts.iter_info = OPTS_GET(opts, link_info, (void *)0);
+	link_create_opts.iter_info_len = OPTS_GET(opts, link_info_len, 0);
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->detach = &bpf_link__detach_fd;
+
+	link_fd = bpf_link_create(prog_fd, target_fd, BPF_TRACE_ITER,
+				  &link_create_opts);
+	if (link_fd < 0) {
+		link_fd = -errno;
+		free(link);
+		pr_warn("prog '%s': failed to attach to iterator: %s\n",
+			prog->name, libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(link_fd);
+	}
+	link->fd = link_fd;
+	return link;
+}
+
+static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	*link = bpf_program__attach_iter(prog, NULL);
+	return libbpf_get_error(*link);
+}
+
+struct bpf_link *bpf_program__attach(const struct bpf_program *prog)
+{
+	struct bpf_link *link = NULL;
+	int err;
+
+	if (!prog->sec_def || !prog->sec_def->prog_attach_fn)
+		return libbpf_err_ptr(-EOPNOTSUPP);
+
+	err = prog->sec_def->prog_attach_fn(prog, prog->sec_def->cookie, &link);
+	if (err)
+		return libbpf_err_ptr(err);
+
+	/* When calling bpf_program__attach() explicitly, auto-attach support
+	 * is expected to work, so NULL returned link is considered an error.
+	 * This is different for skeleton's attach, see comment in
+	 * bpf_object__attach_skeleton().
+	 */
+	if (!link)
+		return libbpf_err_ptr(-EOPNOTSUPP);
+
+	return link;
+}
+
+static int bpf_link__detach_struct_ops(struct bpf_link *link)
+{
+	__u32 zero = 0;
+
+	if (bpf_map_delete_elem(link->fd, &zero))
+		return -errno;
+
+	return 0;
+}
+
+struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map)
+{
+	struct bpf_struct_ops *st_ops;
+	struct bpf_link *link;
+	__u32 i, zero = 0;
+	int err;
+
+	if (!bpf_map__is_struct_ops(map) || map->fd == -1)
+		return libbpf_err_ptr(-EINVAL);
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-EINVAL);
+
+	st_ops = map->st_ops;
+	for (i = 0; i < btf_vlen(st_ops->type); i++) {
+		struct bpf_program *prog = st_ops->progs[i];
+		void *kern_data;
+		int prog_fd;
+
+		if (!prog)
+			continue;
+
+		prog_fd = bpf_program__fd(prog);
+		kern_data = st_ops->kern_vdata + st_ops->kern_func_off[i];
+		*(unsigned long *)kern_data = prog_fd;
+	}
+
+	err = bpf_map_update_elem(map->fd, &zero, st_ops->kern_vdata, 0);
+	if (err) {
+		err = -errno;
+		free(link);
+		return libbpf_err_ptr(err);
+	}
+
+	link->detach = bpf_link__detach_struct_ops;
+	link->fd = map->fd;
+
+	return link;
+}
+
+typedef enum bpf_perf_event_ret (*bpf_perf_event_print_t)(struct perf_event_header *hdr,
+							  void *private_data);
+
+static enum bpf_perf_event_ret
+perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
+		       void **copy_mem, size_t *copy_size,
+		       bpf_perf_event_print_t fn, void *private_data)
+{
+	struct perf_event_mmap_page *header = mmap_mem;
+	__u64 data_head = ring_buffer_read_head(header);
+	__u64 data_tail = header->data_tail;
+	void *base = ((__u8 *)header) + page_size;
+	int ret = LIBBPF_PERF_EVENT_CONT;
+	struct perf_event_header *ehdr;
+	size_t ehdr_size;
+
+	while (data_head != data_tail) {
+		ehdr = base + (data_tail & (mmap_size - 1));
+		ehdr_size = ehdr->size;
+
+		if (((void *)ehdr) + ehdr_size > base + mmap_size) {
+			void *copy_start = ehdr;
+			size_t len_first = base + mmap_size - copy_start;
+			size_t len_secnd = ehdr_size - len_first;
+
+			if (*copy_size < ehdr_size) {
+				free(*copy_mem);
+				*copy_mem = malloc(ehdr_size);
+				if (!*copy_mem) {
+					*copy_size = 0;
+					ret = LIBBPF_PERF_EVENT_ERROR;
+					break;
+				}
+				*copy_size = ehdr_size;
+			}
+
+			memcpy(*copy_mem, copy_start, len_first);
+			memcpy(*copy_mem + len_first, base, len_secnd);
+			ehdr = *copy_mem;
+		}
+
+		ret = fn(ehdr, private_data);
+		data_tail += ehdr_size;
+		if (ret != LIBBPF_PERF_EVENT_CONT)
+			break;
+	}
+
+	ring_buffer_write_tail(header, data_tail);
+	return libbpf_err(ret);
+}
+
+struct perf_buffer;
+
+struct perf_buffer_params {
+	struct perf_event_attr *attr;
+	/* if event_cb is specified, it takes precendence */
+	perf_buffer_event_fn event_cb;
+	/* sample_cb and lost_cb are higher-level common-case callbacks */
+	perf_buffer_sample_fn sample_cb;
+	perf_buffer_lost_fn lost_cb;
+	void *ctx;
+	int cpu_cnt;
+	int *cpus;
+	int *map_keys;
+};
+
+struct perf_cpu_buf {
+	struct perf_buffer *pb;
+	void *base; /* mmap()'ed memory */
+	void *buf; /* for reconstructing segmented data */
+	size_t buf_size;
+	int fd;
+	int cpu;
+	int map_key;
+};
+
+struct perf_buffer {
+	perf_buffer_event_fn event_cb;
+	perf_buffer_sample_fn sample_cb;
+	perf_buffer_lost_fn lost_cb;
+	void *ctx; /* passed into callbacks */
+
+	size_t page_size;
+	size_t mmap_size;
+	struct perf_cpu_buf **cpu_bufs;
+	struct epoll_event *events;
+	int cpu_cnt; /* number of allocated CPU buffers */
+	int epoll_fd; /* perf event FD */
+	int map_fd; /* BPF_MAP_TYPE_PERF_EVENT_ARRAY BPF map FD */
+};
+
+static void perf_buffer__free_cpu_buf(struct perf_buffer *pb,
+				      struct perf_cpu_buf *cpu_buf)
+{
+	if (!cpu_buf)
+		return;
+	if (cpu_buf->base &&
+	    munmap(cpu_buf->base, pb->mmap_size + pb->page_size))
+		pr_warn("failed to munmap cpu_buf #%d\n", cpu_buf->cpu);
+	if (cpu_buf->fd >= 0) {
+		ioctl(cpu_buf->fd, PERF_EVENT_IOC_DISABLE, 0);
+		close(cpu_buf->fd);
+	}
+	free(cpu_buf->buf);
+	free(cpu_buf);
+}
+
+void perf_buffer__free(struct perf_buffer *pb)
+{
+	int i;
+
+	if (IS_ERR_OR_NULL(pb))
+		return;
+	if (pb->cpu_bufs) {
+		for (i = 0; i < pb->cpu_cnt; i++) {
+			struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
+
+			if (!cpu_buf)
+				continue;
+
+			bpf_map_delete_elem(pb->map_fd, &cpu_buf->map_key);
+			perf_buffer__free_cpu_buf(pb, cpu_buf);
+		}
+		free(pb->cpu_bufs);
+	}
+	if (pb->epoll_fd >= 0)
+		close(pb->epoll_fd);
+	free(pb->events);
+	free(pb);
+}
+
+static struct perf_cpu_buf *
+perf_buffer__open_cpu_buf(struct perf_buffer *pb, struct perf_event_attr *attr,
+			  int cpu, int map_key)
+{
+	struct perf_cpu_buf *cpu_buf;
+	char msg[STRERR_BUFSIZE];
+	int err;
+
+	cpu_buf = calloc(1, sizeof(*cpu_buf));
+	if (!cpu_buf)
+		return ERR_PTR(-ENOMEM);
+
+	cpu_buf->pb = pb;
+	cpu_buf->cpu = cpu;
+	cpu_buf->map_key = map_key;
+
+	cpu_buf->fd = syscall(__NR_perf_event_open, attr, -1 /* pid */, cpu,
+			      -1, PERF_FLAG_FD_CLOEXEC);
+	if (cpu_buf->fd < 0) {
+		err = -errno;
+		pr_warn("failed to open perf buffer event on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	cpu_buf->base = mmap(NULL, pb->mmap_size + pb->page_size,
+			     PROT_READ | PROT_WRITE, MAP_SHARED,
+			     cpu_buf->fd, 0);
+	if (cpu_buf->base == MAP_FAILED) {
+		cpu_buf->base = NULL;
+		err = -errno;
+		pr_warn("failed to mmap perf buffer on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	if (ioctl(cpu_buf->fd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
+		err = -errno;
+		pr_warn("failed to enable perf buffer event on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	return cpu_buf;
+
+error:
+	perf_buffer__free_cpu_buf(pb, cpu_buf);
+	return (struct perf_cpu_buf *)ERR_PTR(err);
+}
+
+static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
+					      struct perf_buffer_params *p);
+
+struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
+				     perf_buffer_sample_fn sample_cb,
+				     perf_buffer_lost_fn lost_cb,
+				     void *ctx,
+				     const struct perf_buffer_opts *opts)
+{
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_buffer_params p = {};
+	struct perf_event_attr attr;
+
+	if (!OPTS_VALID(opts, perf_buffer_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.size = attr_sz;
+	attr.config = PERF_COUNT_SW_BPF_OUTPUT;
+	attr.type = PERF_TYPE_SOFTWARE;
+	attr.sample_type = PERF_SAMPLE_RAW;
+	attr.sample_period = 1;
+	attr.wakeup_events = 1;
+
+	p.attr = &attr;
+	p.sample_cb = sample_cb;
+	p.lost_cb = lost_cb;
+	p.ctx = ctx;
+
+	return libbpf_ptr(__perf_buffer__new(map_fd, page_cnt, &p));
+}
+
+struct perf_buffer *perf_buffer__new_raw(int map_fd, size_t page_cnt,
+					 struct perf_event_attr *attr,
+					 perf_buffer_event_fn event_cb, void *ctx,
+					 const struct perf_buffer_raw_opts *opts)
+{
+	struct perf_buffer_params p = {};
+
+	if (!attr)
+		return libbpf_err_ptr(-EINVAL);
+
+	if (!OPTS_VALID(opts, perf_buffer_raw_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	p.attr = attr;
+	p.event_cb = event_cb;
+	p.ctx = ctx;
+	p.cpu_cnt = OPTS_GET(opts, cpu_cnt, 0);
+	p.cpus = OPTS_GET(opts, cpus, NULL);
+	p.map_keys = OPTS_GET(opts, map_keys, NULL);
+
+	return libbpf_ptr(__perf_buffer__new(map_fd, page_cnt, &p));
+}
+
+static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
+					      struct perf_buffer_params *p)
+{
+	const char *online_cpus_file = "/sys/devices/system/cpu/online";
+	struct bpf_map_info map;
+	char msg[STRERR_BUFSIZE];
+	struct perf_buffer *pb;
+	bool *online = NULL;
+	__u32 map_info_len;
+	int err, i, j, n;
+
+	if (page_cnt == 0 || (page_cnt & (page_cnt - 1))) {
+		pr_warn("page count should be power of two, but is %zu\n",
+			page_cnt);
+		return ERR_PTR(-EINVAL);
+	}
+
+	/* best-effort sanity checks */
+	memset(&map, 0, sizeof(map));
+	map_info_len = sizeof(map);
+	err = bpf_obj_get_info_by_fd(map_fd, &map, &map_info_len);
+	if (err) {
+		err = -errno;
+		/* if BPF_OBJ_GET_INFO_BY_FD is supported, will return
+		 * -EBADFD, -EFAULT, or -E2BIG on real error
+		 */
+		if (err != -EINVAL) {
+			pr_warn("failed to get map info for map FD %d: %s\n",
+				map_fd, libbpf_strerror_r(err, msg, sizeof(msg)));
+			return ERR_PTR(err);
+		}
+		pr_debug("failed to get map info for FD %d; API not supported? Ignoring...\n",
+			 map_fd);
+	} else {
+		if (map.type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) {
+			pr_warn("map '%s' should be BPF_MAP_TYPE_PERF_EVENT_ARRAY\n",
+				map.name);
+			return ERR_PTR(-EINVAL);
+		}
+	}
+
+	pb = calloc(1, sizeof(*pb));
+	if (!pb)
+		return ERR_PTR(-ENOMEM);
+
+	pb->event_cb = p->event_cb;
+	pb->sample_cb = p->sample_cb;
+	pb->lost_cb = p->lost_cb;
+	pb->ctx = p->ctx;
+
+	pb->page_size = getpagesize();
+	pb->mmap_size = pb->page_size * page_cnt;
+	pb->map_fd = map_fd;
+
+	pb->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
+	if (pb->epoll_fd < 0) {
+		err = -errno;
+		pr_warn("failed to create epoll instance: %s\n",
+			libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	if (p->cpu_cnt > 0) {
+		pb->cpu_cnt = p->cpu_cnt;
+	} else {
+		pb->cpu_cnt = libbpf_num_possible_cpus();
+		if (pb->cpu_cnt < 0) {
+			err = pb->cpu_cnt;
+			goto error;
+		}
+		if (map.max_entries && map.max_entries < pb->cpu_cnt)
+			pb->cpu_cnt = map.max_entries;
+	}
+
+	pb->events = calloc(pb->cpu_cnt, sizeof(*pb->events));
+	if (!pb->events) {
+		err = -ENOMEM;
+		pr_warn("failed to allocate events: out of memory\n");
+		goto error;
+	}
+	pb->cpu_bufs = calloc(pb->cpu_cnt, sizeof(*pb->cpu_bufs));
+	if (!pb->cpu_bufs) {
+		err = -ENOMEM;
+		pr_warn("failed to allocate buffers: out of memory\n");
+		goto error;
+	}
+
+	err = parse_cpu_mask_file(online_cpus_file, &online, &n);
+	if (err) {
+		pr_warn("failed to get online CPU mask: %d\n", err);
+		goto error;
+	}
+
+	for (i = 0, j = 0; i < pb->cpu_cnt; i++) {
+		struct perf_cpu_buf *cpu_buf;
+		int cpu, map_key;
+
+		cpu = p->cpu_cnt > 0 ? p->cpus[i] : i;
+		map_key = p->cpu_cnt > 0 ? p->map_keys[i] : i;
+
+		/* in case user didn't explicitly requested particular CPUs to
+		 * be attached to, skip offline/not present CPUs
+		 */
+		if (p->cpu_cnt <= 0 && (cpu >= n || !online[cpu]))
+			continue;
+
+		cpu_buf = perf_buffer__open_cpu_buf(pb, p->attr, cpu, map_key);
+		if (IS_ERR(cpu_buf)) {
+			err = PTR_ERR(cpu_buf);
+			goto error;
+		}
+
+		pb->cpu_bufs[j] = cpu_buf;
+
+		err = bpf_map_update_elem(pb->map_fd, &map_key,
+					  &cpu_buf->fd, 0);
+		if (err) {
+			err = -errno;
+			pr_warn("failed to set cpu #%d, key %d -> perf FD %d: %s\n",
+				cpu, map_key, cpu_buf->fd,
+				libbpf_strerror_r(err, msg, sizeof(msg)));
+			goto error;
+		}
+
+		pb->events[j].events = EPOLLIN;
+		pb->events[j].data.ptr = cpu_buf;
+		if (epoll_ctl(pb->epoll_fd, EPOLL_CTL_ADD, cpu_buf->fd,
+			      &pb->events[j]) < 0) {
+			err = -errno;
+			pr_warn("failed to epoll_ctl cpu #%d perf FD %d: %s\n",
+				cpu, cpu_buf->fd,
+				libbpf_strerror_r(err, msg, sizeof(msg)));
+			goto error;
+		}
+		j++;
+	}
+	pb->cpu_cnt = j;
+	free(online);
+
+	return pb;
+
+error:
+	free(online);
+	if (pb)
+		perf_buffer__free(pb);
+	return ERR_PTR(err);
+}
+
+struct perf_sample_raw {
+	struct perf_event_header header;
+	uint32_t size;
+	char data[];
+};
+
+struct perf_sample_lost {
+	struct perf_event_header header;
+	uint64_t id;
+	uint64_t lost;
+	uint64_t sample_id;
+};
+
+static enum bpf_perf_event_ret
+perf_buffer__process_record(struct perf_event_header *e, void *ctx)
+{
+	struct perf_cpu_buf *cpu_buf = ctx;
+	struct perf_buffer *pb = cpu_buf->pb;
+	void *data = e;
+
+	/* user wants full control over parsing perf event */
+	if (pb->event_cb)
+		return pb->event_cb(pb->ctx, cpu_buf->cpu, e);
+
+	switch (e->type) {
+	case PERF_RECORD_SAMPLE: {
+		struct perf_sample_raw *s = data;
+
+		if (pb->sample_cb)
+			pb->sample_cb(pb->ctx, cpu_buf->cpu, s->data, s->size);
+		break;
+	}
+	case PERF_RECORD_LOST: {
+		struct perf_sample_lost *s = data;
+
+		if (pb->lost_cb)
+			pb->lost_cb(pb->ctx, cpu_buf->cpu, s->lost);
+		break;
+	}
+	default:
+		pr_warn("unknown perf sample type %d\n", e->type);
+		return LIBBPF_PERF_EVENT_ERROR;
+	}
+	return LIBBPF_PERF_EVENT_CONT;
+}
+
+static int perf_buffer__process_records(struct perf_buffer *pb,
+					struct perf_cpu_buf *cpu_buf)
+{
+	enum bpf_perf_event_ret ret;
+
+	ret = perf_event_read_simple(cpu_buf->base, pb->mmap_size,
+				     pb->page_size, &cpu_buf->buf,
+				     &cpu_buf->buf_size,
+				     perf_buffer__process_record, cpu_buf);
+	if (ret != LIBBPF_PERF_EVENT_CONT)
+		return ret;
+	return 0;
+}
+
+int perf_buffer__epoll_fd(const struct perf_buffer *pb)
+{
+	return pb->epoll_fd;
+}
+
+int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms)
+{
+	int i, cnt, err;
+
+	cnt = epoll_wait(pb->epoll_fd, pb->events, pb->cpu_cnt, timeout_ms);
+	if (cnt < 0)
+		return -errno;
+
+	for (i = 0; i < cnt; i++) {
+		struct perf_cpu_buf *cpu_buf = pb->events[i].data.ptr;
+
+		err = perf_buffer__process_records(pb, cpu_buf);
+		if (err) {
+			pr_warn("error while processing records: %d\n", err);
+			return libbpf_err(err);
+		}
+	}
+	return cnt;
+}
+
+/* Return number of PERF_EVENT_ARRAY map slots set up by this perf_buffer
+ * manager.
+ */
+size_t perf_buffer__buffer_cnt(const struct perf_buffer *pb)
+{
+	return pb->cpu_cnt;
+}
+
+/*
+ * Return perf_event FD of a ring buffer in *buf_idx* slot of
+ * PERF_EVENT_ARRAY BPF map. This FD can be polled for new data using
+ * select()/poll()/epoll() Linux syscalls.
+ */
+int perf_buffer__buffer_fd(const struct perf_buffer *pb, size_t buf_idx)
+{
+	struct perf_cpu_buf *cpu_buf;
+
+	if (buf_idx >= pb->cpu_cnt)
+		return libbpf_err(-EINVAL);
+
+	cpu_buf = pb->cpu_bufs[buf_idx];
+	if (!cpu_buf)
+		return libbpf_err(-ENOENT);
+
+	return cpu_buf->fd;
+}
+
+int perf_buffer__buffer(struct perf_buffer *pb, int buf_idx, void **buf, size_t *buf_size)
+{
+	struct perf_cpu_buf *cpu_buf;
+
+	if (buf_idx >= pb->cpu_cnt)
+		return libbpf_err(-EINVAL);
+
+	cpu_buf = pb->cpu_bufs[buf_idx];
+	if (!cpu_buf)
+		return libbpf_err(-ENOENT);
+
+	*buf = cpu_buf->base;
+	*buf_size = pb->mmap_size;
+	return 0;
+}
+
+/*
+ * Consume data from perf ring buffer corresponding to slot *buf_idx* in
+ * PERF_EVENT_ARRAY BPF map without waiting/polling. If there is no data to
+ * consume, do nothing and return success.
+ * Returns:
+ *   - 0 on success;
+ *   - <0 on failure.
+ */
+int perf_buffer__consume_buffer(struct perf_buffer *pb, size_t buf_idx)
+{
+	struct perf_cpu_buf *cpu_buf;
+
+	if (buf_idx >= pb->cpu_cnt)
+		return libbpf_err(-EINVAL);
+
+	cpu_buf = pb->cpu_bufs[buf_idx];
+	if (!cpu_buf)
+		return libbpf_err(-ENOENT);
+
+	return perf_buffer__process_records(pb, cpu_buf);
+}
+
+int perf_buffer__consume(struct perf_buffer *pb)
+{
+	int i, err;
+
+	for (i = 0; i < pb->cpu_cnt; i++) {
+		struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
+
+		if (!cpu_buf)
+			continue;
+
+		err = perf_buffer__process_records(pb, cpu_buf);
+		if (err) {
+			pr_warn("perf_buffer: failed to process records in buffer #%d: %d\n", i, err);
+			return libbpf_err(err);
+		}
+	}
+	return 0;
+}
+
+int bpf_program__set_attach_target(struct bpf_program *prog,
+				   int attach_prog_fd,
+				   const char *attach_func_name)
+{
+	int btf_obj_fd = 0, btf_id = 0, err;
+
+	if (!prog || attach_prog_fd < 0)
+		return libbpf_err(-EINVAL);
+
+	if (prog->obj->loaded)
+		return libbpf_err(-EINVAL);
+
+	if (attach_prog_fd && !attach_func_name) {
+		/* remember attach_prog_fd and let bpf_program__load() find
+		 * BTF ID during the program load
+		 */
+		prog->attach_prog_fd = attach_prog_fd;
+		return 0;
+	}
+
+	if (attach_prog_fd) {
+		btf_id = libbpf_find_prog_btf_id(attach_func_name,
+						 attach_prog_fd);
+		if (btf_id < 0)
+			return libbpf_err(btf_id);
+	} else {
+		if (!attach_func_name)
+			return libbpf_err(-EINVAL);
+
+		/* load btf_vmlinux, if not yet */
+		err = bpf_object__load_vmlinux_btf(prog->obj, true);
+		if (err)
+			return libbpf_err(err);
+		err = find_kernel_btf_id(prog->obj, attach_func_name,
+					 prog->expected_attach_type,
+					 &btf_obj_fd, &btf_id);
+		if (err)
+			return libbpf_err(err);
+	}
+
+	prog->attach_btf_id = btf_id;
+	prog->attach_btf_obj_fd = btf_obj_fd;
+	prog->attach_prog_fd = attach_prog_fd;
+	return 0;
+}
+
+int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz)
+{
+	int err = 0, n, len, start, end = -1;
+	bool *tmp;
+
+	*mask = NULL;
+	*mask_sz = 0;
+
+	/* Each sub string separated by ',' has format \d+-\d+ or \d+ */
+	while (*s) {
+		if (*s == ',' || *s == '\n') {
+			s++;
+			continue;
+		}
+		n = sscanf(s, "%d%n-%d%n", &start, &len, &end, &len);
+		if (n <= 0 || n > 2) {
+			pr_warn("Failed to get CPU range %s: %d\n", s, n);
+			err = -EINVAL;
+			goto cleanup;
+		} else if (n == 1) {
+			end = start;
+		}
+		if (start < 0 || start > end) {
+			pr_warn("Invalid CPU range [%d,%d] in %s\n",
+				start, end, s);
+			err = -EINVAL;
+			goto cleanup;
+		}
+		tmp = realloc(*mask, end + 1);
+		if (!tmp) {
+			err = -ENOMEM;
+			goto cleanup;
+		}
+		*mask = tmp;
+		memset(tmp + *mask_sz, 0, start - *mask_sz);
+		memset(tmp + start, 1, end - start + 1);
+		*mask_sz = end + 1;
+		s += len;
+	}
+	if (!*mask_sz) {
+		pr_warn("Empty CPU range\n");
+		return -EINVAL;
+	}
+	return 0;
+cleanup:
+	free(*mask);
+	*mask = NULL;
+	return err;
+}
+
+int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz)
+{
+	int fd, err = 0, len;
+	char buf[128];
+
+	fd = open(fcpu, O_RDONLY | O_CLOEXEC);
+	if (fd < 0) {
+		err = -errno;
+		pr_warn("Failed to open cpu mask file %s: %d\n", fcpu, err);
+		return err;
+	}
+	len = read(fd, buf, sizeof(buf));
+	close(fd);
+	if (len <= 0) {
+		err = len ? -errno : -EINVAL;
+		pr_warn("Failed to read cpu mask from %s: %d\n", fcpu, err);
+		return err;
+	}
+	if (len >= sizeof(buf)) {
+		pr_warn("CPU mask is too big in file %s\n", fcpu);
+		return -E2BIG;
+	}
+	buf[len] = '\0';
+
+	return parse_cpu_mask_str(buf, mask, mask_sz);
+}
+
+int libbpf_num_possible_cpus(void)
+{
+	static const char *fcpu = "/sys/devices/system/cpu/possible";
+	static int cpus;
+	int err, n, i, tmp_cpus;
+	bool *mask;
+
+	tmp_cpus = READ_ONCE(cpus);
+	if (tmp_cpus > 0)
+		return tmp_cpus;
+
+	err = parse_cpu_mask_file(fcpu, &mask, &n);
+	if (err)
+		return libbpf_err(err);
+
+	tmp_cpus = 0;
+	for (i = 0; i < n; i++) {
+		if (mask[i])
+			tmp_cpus++;
+	}
+	free(mask);
+
+	WRITE_ONCE(cpus, tmp_cpus);
+	return tmp_cpus;
+}
+
+static int populate_skeleton_maps(const struct bpf_object *obj,
+				  struct bpf_map_skeleton *maps,
+				  size_t map_cnt)
+{
+	int i;
+
+	for (i = 0; i < map_cnt; i++) {
+		struct bpf_map **map = maps[i].map;
+		const char *name = maps[i].name;
+		void **mmaped = maps[i].mmaped;
+
+		*map = bpf_object__find_map_by_name(obj, name);
+		if (!*map) {
+			pr_warn("failed to find skeleton map '%s'\n", name);
+			return -ESRCH;
+		}
+
+		/* externs shouldn't be pre-setup from user code */
+		if (mmaped && (*map)->libbpf_type != LIBBPF_MAP_KCONFIG)
+			*mmaped = (*map)->mmaped;
+	}
+	return 0;
+}
+
+static int populate_skeleton_progs(const struct bpf_object *obj,
+				   struct bpf_prog_skeleton *progs,
+				   size_t prog_cnt)
+{
+	int i;
+
+	for (i = 0; i < prog_cnt; i++) {
+		struct bpf_program **prog = progs[i].prog;
+		const char *name = progs[i].name;
+
+		*prog = bpf_object__find_program_by_name(obj, name);
+		if (!*prog) {
+			pr_warn("failed to find skeleton program '%s'\n", name);
+			return -ESRCH;
+		}
+	}
+	return 0;
+}
+
+int bpf_object__open_skeleton(struct bpf_object_skeleton *s,
+			      const struct bpf_object_open_opts *opts)
+{
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, skel_opts,
+		.object_name = s->name,
+	);
+	struct bpf_object *obj;
+	int err;
+
+	/* Attempt to preserve opts->object_name, unless overriden by user
+	 * explicitly. Overwriting object name for skeletons is discouraged,
+	 * as it breaks global data maps, because they contain object name
+	 * prefix as their own map name prefix. When skeleton is generated,
+	 * bpftool is making an assumption that this name will stay the same.
+	 */
+	if (opts) {
+		memcpy(&skel_opts, opts, sizeof(*opts));
+		if (!opts->object_name)
+			skel_opts.object_name = s->name;
+	}
+
+	obj = bpf_object__open_mem(s->data, s->data_sz, &skel_opts);
+	err = libbpf_get_error(obj);
+	if (err) {
+		pr_warn("failed to initialize skeleton BPF object '%s': %d\n",
+			s->name, err);
+		return libbpf_err(err);
+	}
+
+	*s->obj = obj;
+	err = populate_skeleton_maps(obj, s->maps, s->map_cnt);
+	if (err) {
+		pr_warn("failed to populate skeleton maps for '%s': %d\n", s->name, err);
+		return libbpf_err(err);
+	}
+
+	err = populate_skeleton_progs(obj, s->progs, s->prog_cnt);
+	if (err) {
+		pr_warn("failed to populate skeleton progs for '%s': %d\n", s->name, err);
+		return libbpf_err(err);
+	}
+
+	return 0;
+}
+
+int bpf_object__open_subskeleton(struct bpf_object_subskeleton *s)
+{
+	int err, len, var_idx, i;
+	const char *var_name;
+	const struct bpf_map *map;
+	struct btf *btf;
+	__u32 map_type_id;
+	const struct btf_type *map_type, *var_type;
+	const struct bpf_var_skeleton *var_skel;
+	struct btf_var_secinfo *var;
+
+	if (!s->obj)
+		return libbpf_err(-EINVAL);
+
+	btf = bpf_object__btf(s->obj);
+	if (!btf) {
+		pr_warn("subskeletons require BTF at runtime (object %s)\n",
+			bpf_object__name(s->obj));
+		return libbpf_err(-errno);
+	}
+
+	err = populate_skeleton_maps(s->obj, s->maps, s->map_cnt);
+	if (err) {
+		pr_warn("failed to populate subskeleton maps: %d\n", err);
+		return libbpf_err(err);
+	}
+
+	err = populate_skeleton_progs(s->obj, s->progs, s->prog_cnt);
+	if (err) {
+		pr_warn("failed to populate subskeleton maps: %d\n", err);
+		return libbpf_err(err);
+	}
+
+	for (var_idx = 0; var_idx < s->var_cnt; var_idx++) {
+		var_skel = &s->vars[var_idx];
+		map = *var_skel->map;
+		map_type_id = bpf_map__btf_value_type_id(map);
+		map_type = btf__type_by_id(btf, map_type_id);
+
+		if (!btf_is_datasec(map_type)) {
+			pr_warn("type for map '%1$s' is not a datasec: %2$s",
+				bpf_map__name(map),
+				__btf_kind_str(btf_kind(map_type)));
+			return libbpf_err(-EINVAL);
+		}
+
+		len = btf_vlen(map_type);
+		var = btf_var_secinfos(map_type);
+		for (i = 0; i < len; i++, var++) {
+			var_type = btf__type_by_id(btf, var->type);
+			var_name = btf__name_by_offset(btf, var_type->name_off);
+			if (strcmp(var_name, var_skel->name) == 0) {
+				*var_skel->addr = map->mmaped + var->offset;
+				break;
+			}
+		}
+	}
+	return 0;
+}
+
+void bpf_object__destroy_subskeleton(struct bpf_object_subskeleton *s)
+{
+	if (!s)
+		return;
+	free(s->maps);
+	free(s->progs);
+	free(s->vars);
+	free(s);
+}
+
+int bpf_object__load_skeleton(struct bpf_object_skeleton *s)
+{
+	int i, err;
+
+	err = bpf_object__load(*s->obj);
+	if (err) {
+		pr_warn("failed to load BPF skeleton '%s': %d\n", s->name, err);
+		return libbpf_err(err);
+	}
+
+	for (i = 0; i < s->map_cnt; i++) {
+		struct bpf_map *map = *s->maps[i].map;
+		size_t mmap_sz = bpf_map_mmap_sz(map);
+		int prot, map_fd = bpf_map__fd(map);
+		void **mmaped = s->maps[i].mmaped;
+
+		if (!mmaped)
+			continue;
+
+		if (!(map->def.map_flags & BPF_F_MMAPABLE)) {
+			*mmaped = NULL;
+			continue;
+		}
+
+		if (map->def.map_flags & BPF_F_RDONLY_PROG)
+			prot = PROT_READ;
+		else
+			prot = PROT_READ | PROT_WRITE;
+
+		/* Remap anonymous mmap()-ed "map initialization image" as
+		 * a BPF map-backed mmap()-ed memory, but preserving the same
+		 * memory address. This will cause kernel to change process'
+		 * page table to point to a different piece of kernel memory,
+		 * but from userspace point of view memory address (and its
+		 * contents, being identical at this point) will stay the
+		 * same. This mapping will be released by bpf_object__close()
+		 * as per normal clean up procedure, so we don't need to worry
+		 * about it from skeleton's clean up perspective.
+		 */
+		*mmaped = mmap(map->mmaped, mmap_sz, prot,
+				MAP_SHARED | MAP_FIXED, map_fd, 0);
+		if (*mmaped == MAP_FAILED) {
+			err = -errno;
+			*mmaped = NULL;
+			pr_warn("failed to re-mmap() map '%s': %d\n",
+				 bpf_map__name(map), err);
+			return libbpf_err(err);
+		}
+	}
+
+	return 0;
+}
+
+int bpf_object__attach_skeleton(struct bpf_object_skeleton *s)
+{
+	int i, err;
+
+	for (i = 0; i < s->prog_cnt; i++) {
+		struct bpf_program *prog = *s->progs[i].prog;
+		struct bpf_link **link = s->progs[i].link;
+
+		if (!prog->autoload || !prog->autoattach)
+			continue;
+
+		/* auto-attaching not supported for this program */
+		if (!prog->sec_def || !prog->sec_def->prog_attach_fn)
+			continue;
+
+		/* if user already set the link manually, don't attempt auto-attach */
+		if (*link)
+			continue;
+
+		err = prog->sec_def->prog_attach_fn(prog, prog->sec_def->cookie, link);
+		if (err) {
+			pr_warn("prog '%s': failed to auto-attach: %d\n",
+				bpf_program__name(prog), err);
+			return libbpf_err(err);
+		}
+
+		/* It's possible that for some SEC() definitions auto-attach
+		 * is supported in some cases (e.g., if definition completely
+		 * specifies target information), but is not in other cases.
+		 * SEC("uprobe") is one such case. If user specified target
+		 * binary and function name, such BPF program can be
+		 * auto-attached. But if not, it shouldn't trigger skeleton's
+		 * attach to fail. It should just be skipped.
+		 * attach_fn signals such case with returning 0 (no error) and
+		 * setting link to NULL.
+		 */
+	}
+
+	return 0;
+}
+
+void bpf_object__detach_skeleton(struct bpf_object_skeleton *s)
+{
+	int i;
+
+	for (i = 0; i < s->prog_cnt; i++) {
+		struct bpf_link **link = s->progs[i].link;
+
+		bpf_link__destroy(*link);
+		*link = NULL;
+	}
+}
+
+void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s)
+{
+	if (!s)
+		return;
+
+	if (s->progs)
+		bpf_object__detach_skeleton(s);
+	if (s->obj)
+		bpf_object__close(*s->obj);
+	free(s->maps);
+	free(s->progs);
+	free(s);
+}
diff --git a/src/libbpf.h b/src/libbpf.h
new file mode 100644
index 0000000..eee883f
--- /dev/null
+++ b/src/libbpf.h
@@ -0,0 +1,1529 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Common eBPF ELF object loading operations.
+ *
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ */
+#ifndef __LIBBPF_LIBBPF_H
+#define __LIBBPF_LIBBPF_H
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <sys/types.h>  // for size_t
+#include <linux/bpf.h>
+
+#include "libbpf_common.h"
+#include "libbpf_legacy.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+LIBBPF_API __u32 libbpf_major_version(void);
+LIBBPF_API __u32 libbpf_minor_version(void);
+LIBBPF_API const char *libbpf_version_string(void);
+
+enum libbpf_errno {
+	__LIBBPF_ERRNO__START = 4000,
+
+	/* Something wrong in libelf */
+	LIBBPF_ERRNO__LIBELF = __LIBBPF_ERRNO__START,
+	LIBBPF_ERRNO__FORMAT,	/* BPF object format invalid */
+	LIBBPF_ERRNO__KVERSION,	/* Incorrect or no 'version' section */
+	LIBBPF_ERRNO__ENDIAN,	/* Endian mismatch */
+	LIBBPF_ERRNO__INTERNAL,	/* Internal error in libbpf */
+	LIBBPF_ERRNO__RELOC,	/* Relocation failed */
+	LIBBPF_ERRNO__LOAD,	/* Load program failure for unknown reason */
+	LIBBPF_ERRNO__VERIFY,	/* Kernel verifier blocks program loading */
+	LIBBPF_ERRNO__PROG2BIG,	/* Program too big */
+	LIBBPF_ERRNO__KVER,	/* Incorrect kernel version */
+	LIBBPF_ERRNO__PROGTYPE,	/* Kernel doesn't support this program type */
+	LIBBPF_ERRNO__WRNGPID,	/* Wrong pid in netlink message */
+	LIBBPF_ERRNO__INVSEQ,	/* Invalid netlink sequence */
+	LIBBPF_ERRNO__NLPARSE,	/* netlink parsing error */
+	__LIBBPF_ERRNO__END,
+};
+
+LIBBPF_API int libbpf_strerror(int err, char *buf, size_t size);
+
+/**
+ * @brief **libbpf_bpf_attach_type_str()** converts the provided attach type
+ * value into a textual representation.
+ * @param t The attach type.
+ * @return Pointer to a static string identifying the attach type. NULL is
+ * returned for unknown **bpf_attach_type** values.
+ */
+LIBBPF_API const char *libbpf_bpf_attach_type_str(enum bpf_attach_type t);
+
+/**
+ * @brief **libbpf_bpf_link_type_str()** converts the provided link type value
+ * into a textual representation.
+ * @param t The link type.
+ * @return Pointer to a static string identifying the link type. NULL is
+ * returned for unknown **bpf_link_type** values.
+ */
+LIBBPF_API const char *libbpf_bpf_link_type_str(enum bpf_link_type t);
+
+/**
+ * @brief **libbpf_bpf_map_type_str()** converts the provided map type value
+ * into a textual representation.
+ * @param t The map type.
+ * @return Pointer to a static string identifying the map type. NULL is
+ * returned for unknown **bpf_map_type** values.
+ */
+LIBBPF_API const char *libbpf_bpf_map_type_str(enum bpf_map_type t);
+
+/**
+ * @brief **libbpf_bpf_prog_type_str()** converts the provided program type
+ * value into a textual representation.
+ * @param t The program type.
+ * @return Pointer to a static string identifying the program type. NULL is
+ * returned for unknown **bpf_prog_type** values.
+ */
+LIBBPF_API const char *libbpf_bpf_prog_type_str(enum bpf_prog_type t);
+
+enum libbpf_print_level {
+        LIBBPF_WARN,
+        LIBBPF_INFO,
+        LIBBPF_DEBUG,
+};
+
+typedef int (*libbpf_print_fn_t)(enum libbpf_print_level level,
+				 const char *, va_list ap);
+
+LIBBPF_API libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn);
+
+/* Hide internal to user */
+struct bpf_object;
+
+struct bpf_object_open_opts {
+	/* size of this struct, for forward/backward compatibility */
+	size_t sz;
+	/* object name override, if provided:
+	 * - for object open from file, this will override setting object
+	 *   name from file path's base name;
+	 * - for object open from memory buffer, this will specify an object
+	 *   name and will override default "<addr>-<buf-size>" name;
+	 */
+	const char *object_name;
+	/* parse map definitions non-strictly, allowing extra attributes/data */
+	bool relaxed_maps;
+	/* maps that set the 'pinning' attribute in their definition will have
+	 * their pin_path attribute set to a file in this directory, and be
+	 * auto-pinned to that path on load; defaults to "/sys/fs/bpf".
+	 */
+	const char *pin_root_path;
+
+	__u32 :32; /* stub out now removed attach_prog_fd */
+
+	/* Additional kernel config content that augments and overrides
+	 * system Kconfig for CONFIG_xxx externs.
+	 */
+	const char *kconfig;
+	/* Path to the custom BTF to be used for BPF CO-RE relocations.
+	 * This custom BTF completely replaces the use of vmlinux BTF
+	 * for the purpose of CO-RE relocations.
+	 * NOTE: any other BPF feature (e.g., fentry/fexit programs,
+	 * struct_ops, etc) will need actual kernel BTF at /sys/kernel/btf/vmlinux.
+	 */
+	const char *btf_custom_path;
+	/* Pointer to a buffer for storing kernel logs for applicable BPF
+	 * commands. Valid kernel_log_size has to be specified as well and are
+	 * passed-through to bpf() syscall. Keep in mind that kernel might
+	 * fail operation with -ENOSPC error if provided buffer is too small
+	 * to contain entire log output.
+	 * See the comment below for kernel_log_level for interaction between
+	 * log_buf and log_level settings.
+	 *
+	 * If specified, this log buffer will be passed for:
+	 *   - each BPF progral load (BPF_PROG_LOAD) attempt, unless overriden
+	 *     with bpf_program__set_log() on per-program level, to get
+	 *     BPF verifier log output.
+	 *   - during BPF object's BTF load into kernel (BPF_BTF_LOAD) to get
+	 *     BTF sanity checking log.
+	 *
+	 * Each BPF command (BPF_BTF_LOAD or BPF_PROG_LOAD) will overwrite
+	 * previous contents, so if you need more fine-grained control, set
+	 * per-program buffer with bpf_program__set_log_buf() to preserve each
+	 * individual program's verification log. Keep using kernel_log_buf
+	 * for BTF verification log, if necessary.
+	 */
+	char *kernel_log_buf;
+	size_t kernel_log_size;
+	/*
+	 * Log level can be set independently from log buffer. Log_level=0
+	 * means that libbpf will attempt loading BTF or program without any
+	 * logging requested, but will retry with either its own or custom log
+	 * buffer, if provided, and log_level=1 on any error.
+	 * And vice versa, setting log_level>0 will request BTF or prog
+	 * loading with verbose log from the first attempt (and as such also
+	 * for successfully loaded BTF or program), and the actual log buffer
+	 * could be either libbpf's own auto-allocated log buffer, if
+	 * kernel_log_buffer is NULL, or user-provided custom kernel_log_buf.
+	 * If user didn't provide custom log buffer, libbpf will emit captured
+	 * logs through its print callback.
+	 */
+	__u32 kernel_log_level;
+
+	size_t :0;
+};
+#define bpf_object_open_opts__last_field kernel_log_level
+
+LIBBPF_API struct bpf_object *bpf_object__open(const char *path);
+
+/**
+ * @brief **bpf_object__open_file()** creates a bpf_object by opening
+ * the BPF ELF object file pointed to by the passed path and loading it
+ * into memory.
+ * @param path BPF object file path
+ * @param opts options for how to load the bpf object, this parameter is
+ * optional and can be set to NULL
+ * @return pointer to the new bpf_object; or NULL is returned on error,
+ * error code is stored in errno
+ */
+LIBBPF_API struct bpf_object *
+bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts);
+
+/**
+ * @brief **bpf_object__open_mem()** creates a bpf_object by reading
+ * the BPF objects raw bytes from a memory buffer containing a valid
+ * BPF ELF object file.
+ * @param obj_buf pointer to the buffer containing ELF file bytes
+ * @param obj_buf_sz number of bytes in the buffer
+ * @param opts options for how to load the bpf object
+ * @return pointer to the new bpf_object; or NULL is returned on error,
+ * error code is stored in errno
+ */
+LIBBPF_API struct bpf_object *
+bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
+		     const struct bpf_object_open_opts *opts);
+
+/* Load/unload object into/from kernel */
+LIBBPF_API int bpf_object__load(struct bpf_object *obj);
+
+LIBBPF_API void bpf_object__close(struct bpf_object *object);
+
+/* pin_maps and unpin_maps can both be called with a NULL path, in which case
+ * they will use the pin_path attribute of each map (and ignore all maps that
+ * don't have a pin_path set).
+ */
+LIBBPF_API int bpf_object__pin_maps(struct bpf_object *obj, const char *path);
+LIBBPF_API int bpf_object__unpin_maps(struct bpf_object *obj,
+				      const char *path);
+LIBBPF_API int bpf_object__pin_programs(struct bpf_object *obj,
+					const char *path);
+LIBBPF_API int bpf_object__unpin_programs(struct bpf_object *obj,
+					  const char *path);
+LIBBPF_API int bpf_object__pin(struct bpf_object *object, const char *path);
+
+LIBBPF_API const char *bpf_object__name(const struct bpf_object *obj);
+LIBBPF_API unsigned int bpf_object__kversion(const struct bpf_object *obj);
+LIBBPF_API int bpf_object__set_kversion(struct bpf_object *obj, __u32 kern_version);
+
+struct btf;
+LIBBPF_API struct btf *bpf_object__btf(const struct bpf_object *obj);
+LIBBPF_API int bpf_object__btf_fd(const struct bpf_object *obj);
+
+LIBBPF_API struct bpf_program *
+bpf_object__find_program_by_name(const struct bpf_object *obj,
+				 const char *name);
+
+LIBBPF_API int
+libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
+			 enum bpf_attach_type *expected_attach_type);
+LIBBPF_API int libbpf_attach_type_by_name(const char *name,
+					  enum bpf_attach_type *attach_type);
+LIBBPF_API int libbpf_find_vmlinux_btf_id(const char *name,
+					  enum bpf_attach_type attach_type);
+
+/* Accessors of bpf_program */
+struct bpf_program;
+
+LIBBPF_API struct bpf_program *
+bpf_object__next_program(const struct bpf_object *obj, struct bpf_program *prog);
+
+#define bpf_object__for_each_program(pos, obj)			\
+	for ((pos) = bpf_object__next_program((obj), NULL);	\
+	     (pos) != NULL;					\
+	     (pos) = bpf_object__next_program((obj), (pos)))
+
+LIBBPF_API struct bpf_program *
+bpf_object__prev_program(const struct bpf_object *obj, struct bpf_program *prog);
+
+LIBBPF_API void bpf_program__set_ifindex(struct bpf_program *prog,
+					 __u32 ifindex);
+
+LIBBPF_API const char *bpf_program__name(const struct bpf_program *prog);
+LIBBPF_API const char *bpf_program__section_name(const struct bpf_program *prog);
+LIBBPF_API bool bpf_program__autoload(const struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_autoload(struct bpf_program *prog, bool autoload);
+LIBBPF_API bool bpf_program__autoattach(const struct bpf_program *prog);
+LIBBPF_API void bpf_program__set_autoattach(struct bpf_program *prog, bool autoattach);
+
+struct bpf_insn;
+
+/**
+ * @brief **bpf_program__insns()** gives read-only access to BPF program's
+ * underlying BPF instructions.
+ * @param prog BPF program for which to return instructions
+ * @return a pointer to an array of BPF instructions that belong to the
+ * specified BPF program
+ *
+ * Returned pointer is always valid and not NULL. Number of `struct bpf_insn`
+ * pointed to can be fetched using **bpf_program__insn_cnt()** API.
+ *
+ * Keep in mind, libbpf can modify and append/delete BPF program's
+ * instructions as it processes BPF object file and prepares everything for
+ * uploading into the kernel. So depending on the point in BPF object
+ * lifetime, **bpf_program__insns()** can return different sets of
+ * instructions. As an example, during BPF object load phase BPF program
+ * instructions will be CO-RE-relocated, BPF subprograms instructions will be
+ * appended, ldimm64 instructions will have FDs embedded, etc. So instructions
+ * returned before **bpf_object__load()** and after it might be quite
+ * different.
+ */
+LIBBPF_API const struct bpf_insn *bpf_program__insns(const struct bpf_program *prog);
+
+/**
+ * @brief **bpf_program__set_insns()** can set BPF program's underlying
+ * BPF instructions.
+ *
+ * WARNING: This is a very advanced libbpf API and users need to know
+ * what they are doing. This should be used from prog_prepare_load_fn
+ * callback only.
+ *
+ * @param prog BPF program for which to return instructions
+ * @param new_insns a pointer to an array of BPF instructions
+ * @param new_insn_cnt number of `struct bpf_insn`'s that form
+ * specified BPF program
+ * @return 0, on success; negative error code, otherwise
+ */
+LIBBPF_API int bpf_program__set_insns(struct bpf_program *prog,
+				      struct bpf_insn *new_insns, size_t new_insn_cnt);
+
+/**
+ * @brief **bpf_program__insn_cnt()** returns number of `struct bpf_insn`'s
+ * that form specified BPF program.
+ * @param prog BPF program for which to return number of BPF instructions
+ *
+ * See **bpf_program__insns()** documentation for notes on how libbpf can
+ * change instructions and their count during different phases of
+ * **bpf_object** lifetime.
+ */
+LIBBPF_API size_t bpf_program__insn_cnt(const struct bpf_program *prog);
+
+LIBBPF_API int bpf_program__fd(const struct bpf_program *prog);
+
+/**
+ * @brief **bpf_program__pin()** pins the BPF program to a file
+ * in the BPF FS specified by a path. This increments the programs
+ * reference count, allowing it to stay loaded after the process
+ * which loaded it has exited.
+ *
+ * @param prog BPF program to pin, must already be loaded
+ * @param path file path in a BPF file system
+ * @return 0, on success; negative error code, otherwise
+ */
+LIBBPF_API int bpf_program__pin(struct bpf_program *prog, const char *path);
+
+/**
+ * @brief **bpf_program__unpin()** unpins the BPF program from a file
+ * in the BPFFS specified by a path. This decrements the programs
+ * reference count.
+ *
+ * The file pinning the BPF program can also be unlinked by a different
+ * process in which case this function will return an error.
+ *
+ * @param prog BPF program to unpin
+ * @param path file path to the pin in a BPF file system
+ * @return 0, on success; negative error code, otherwise
+ */
+LIBBPF_API int bpf_program__unpin(struct bpf_program *prog, const char *path);
+LIBBPF_API void bpf_program__unload(struct bpf_program *prog);
+
+struct bpf_link;
+
+LIBBPF_API struct bpf_link *bpf_link__open(const char *path);
+LIBBPF_API int bpf_link__fd(const struct bpf_link *link);
+LIBBPF_API const char *bpf_link__pin_path(const struct bpf_link *link);
+/**
+ * @brief **bpf_link__pin()** pins the BPF link to a file
+ * in the BPF FS specified by a path. This increments the links
+ * reference count, allowing it to stay loaded after the process
+ * which loaded it has exited.
+ *
+ * @param link BPF link to pin, must already be loaded
+ * @param path file path in a BPF file system
+ * @return 0, on success; negative error code, otherwise
+ */
+
+LIBBPF_API int bpf_link__pin(struct bpf_link *link, const char *path);
+
+/**
+ * @brief **bpf_link__unpin()** unpins the BPF link from a file
+ * in the BPFFS specified by a path. This decrements the links
+ * reference count.
+ *
+ * The file pinning the BPF link can also be unlinked by a different
+ * process in which case this function will return an error.
+ *
+ * @param prog BPF program to unpin
+ * @param path file path to the pin in a BPF file system
+ * @return 0, on success; negative error code, otherwise
+ */
+LIBBPF_API int bpf_link__unpin(struct bpf_link *link);
+LIBBPF_API int bpf_link__update_program(struct bpf_link *link,
+					struct bpf_program *prog);
+LIBBPF_API void bpf_link__disconnect(struct bpf_link *link);
+LIBBPF_API int bpf_link__detach(struct bpf_link *link);
+LIBBPF_API int bpf_link__destroy(struct bpf_link *link);
+
+/**
+ * @brief **bpf_program__attach()** is a generic function for attaching
+ * a BPF program based on auto-detection of program type, attach type,
+ * and extra paremeters, where applicable.
+ *
+ * @param prog BPF program to attach
+ * @return Reference to the newly created BPF link; or NULL is returned on error,
+ * error code is stored in errno
+ *
+ * This is supported for:
+ *   - kprobe/kretprobe (depends on SEC() definition)
+ *   - uprobe/uretprobe (depends on SEC() definition)
+ *   - tracepoint
+ *   - raw tracepoint
+ *   - tracing programs (typed raw TP/fentry/fexit/fmod_ret)
+ */
+LIBBPF_API struct bpf_link *
+bpf_program__attach(const struct bpf_program *prog);
+
+struct bpf_perf_event_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* custom user-provided value fetchable through bpf_get_attach_cookie() */
+	__u64 bpf_cookie;
+};
+#define bpf_perf_event_opts__last_field bpf_cookie
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_perf_event(const struct bpf_program *prog, int pfd);
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_perf_event_opts(const struct bpf_program *prog, int pfd,
+				    const struct bpf_perf_event_opts *opts);
+
+struct bpf_kprobe_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* custom user-provided value fetchable through bpf_get_attach_cookie() */
+	__u64 bpf_cookie;
+	/* function's offset to install kprobe to */
+	size_t offset;
+	/* kprobe is return probe */
+	bool retprobe;
+	size_t :0;
+};
+#define bpf_kprobe_opts__last_field retprobe
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_kprobe(const struct bpf_program *prog, bool retprobe,
+			   const char *func_name);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_kprobe_opts(const struct bpf_program *prog,
+                                const char *func_name,
+                                const struct bpf_kprobe_opts *opts);
+
+struct bpf_kprobe_multi_opts {
+	/* size of this struct, for forward/backward compatibility */
+	size_t sz;
+	/* array of function symbols to attach */
+	const char **syms;
+	/* array of function addresses to attach */
+	const unsigned long *addrs;
+	/* array of user-provided values fetchable through bpf_get_attach_cookie */
+	const __u64 *cookies;
+	/* number of elements in syms/addrs/cookies arrays */
+	size_t cnt;
+	/* create return kprobes */
+	bool retprobe;
+	size_t :0;
+};
+
+#define bpf_kprobe_multi_opts__last_field retprobe
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
+				      const char *pattern,
+				      const struct bpf_kprobe_multi_opts *opts);
+
+struct bpf_ksyscall_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* custom user-provided value fetchable through bpf_get_attach_cookie() */
+	__u64 bpf_cookie;
+	/* attach as return probe? */
+	bool retprobe;
+	size_t :0;
+};
+#define bpf_ksyscall_opts__last_field retprobe
+
+/**
+ * @brief **bpf_program__attach_ksyscall()** attaches a BPF program
+ * to kernel syscall handler of a specified syscall. Optionally it's possible
+ * to request to install retprobe that will be triggered at syscall exit. It's
+ * also possible to associate BPF cookie (though options).
+ *
+ * Libbpf automatically will determine correct full kernel function name,
+ * which depending on system architecture and kernel version/configuration
+ * could be of the form __<arch>_sys_<syscall> or __se_sys_<syscall>, and will
+ * attach specified program using kprobe/kretprobe mechanism.
+ *
+ * **bpf_program__attach_ksyscall()** is an API counterpart of declarative
+ * **SEC("ksyscall/<syscall>")** annotation of BPF programs.
+ *
+ * At the moment **SEC("ksyscall")** and **bpf_program__attach_ksyscall()** do
+ * not handle all the calling convention quirks for mmap(), clone() and compat
+ * syscalls. It also only attaches to "native" syscall interfaces. If host
+ * system supports compat syscalls or defines 32-bit syscalls in 64-bit
+ * kernel, such syscall interfaces won't be attached to by libbpf.
+ *
+ * These limitations may or may not change in the future. Therefore it is
+ * recommended to use SEC("kprobe") for these syscalls or if working with
+ * compat and 32-bit interfaces is required.
+ *
+ * @param prog BPF program to attach
+ * @param syscall_name Symbolic name of the syscall (e.g., "bpf")
+ * @param opts Additional options (see **struct bpf_ksyscall_opts**)
+ * @return Reference to the newly created BPF link; or NULL is returned on
+ * error, error code is stored in errno
+ */
+LIBBPF_API struct bpf_link *
+bpf_program__attach_ksyscall(const struct bpf_program *prog,
+			     const char *syscall_name,
+			     const struct bpf_ksyscall_opts *opts);
+
+struct bpf_uprobe_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* offset of kernel reference counted USDT semaphore, added in
+	 * a6ca88b241d5 ("trace_uprobe: support reference counter in fd-based uprobe")
+	 */
+	size_t ref_ctr_offset;
+	/* custom user-provided value fetchable through bpf_get_attach_cookie() */
+	__u64 bpf_cookie;
+	/* uprobe is return probe, invoked at function return time */
+	bool retprobe;
+	/* Function name to attach to.  Could be an unqualified ("abc") or library-qualified
+	 * "abc@LIBXYZ" name.  To specify function entry, func_name should be set while
+	 * func_offset argument to bpf_prog__attach_uprobe_opts() should be 0.  To trace an
+	 * offset within a function, specify func_name and use func_offset argument to specify
+	 * offset within the function.  Shared library functions must specify the shared library
+	 * binary_path.
+	 */
+	const char *func_name;
+	size_t :0;
+};
+#define bpf_uprobe_opts__last_field func_name
+
+/**
+ * @brief **bpf_program__attach_uprobe()** attaches a BPF program
+ * to the userspace function which is found by binary path and
+ * offset. You can optionally specify a particular proccess to attach
+ * to. You can also optionally attach the program to the function
+ * exit instead of entry.
+ *
+ * @param prog BPF program to attach
+ * @param retprobe Attach to function exit
+ * @param pid Process ID to attach the uprobe to, 0 for self (own process),
+ * -1 for all processes
+ * @param binary_path Path to binary that contains the function symbol
+ * @param func_offset Offset within the binary of the function symbol
+ * @return Reference to the newly created BPF link; or NULL is returned on error,
+ * error code is stored in errno
+ */
+LIBBPF_API struct bpf_link *
+bpf_program__attach_uprobe(const struct bpf_program *prog, bool retprobe,
+			   pid_t pid, const char *binary_path,
+			   size_t func_offset);
+
+/**
+ * @brief **bpf_program__attach_uprobe_opts()** is just like
+ * bpf_program__attach_uprobe() except with a options struct
+ * for various configurations.
+ *
+ * @param prog BPF program to attach
+ * @param pid Process ID to attach the uprobe to, 0 for self (own process),
+ * -1 for all processes
+ * @param binary_path Path to binary that contains the function symbol
+ * @param func_offset Offset within the binary of the function symbol
+ * @param opts Options for altering program attachment
+ * @return Reference to the newly created BPF link; or NULL is returned on error,
+ * error code is stored in errno
+ */
+LIBBPF_API struct bpf_link *
+bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
+				const char *binary_path, size_t func_offset,
+				const struct bpf_uprobe_opts *opts);
+
+struct bpf_usdt_opts {
+	/* size of this struct, for forward/backward compatibility */
+	size_t sz;
+	/* custom user-provided value accessible through usdt_cookie() */
+	__u64 usdt_cookie;
+	size_t :0;
+};
+#define bpf_usdt_opts__last_field usdt_cookie
+
+/**
+ * @brief **bpf_program__attach_usdt()** is just like
+ * bpf_program__attach_uprobe_opts() except it covers USDT (User-space
+ * Statically Defined Tracepoint) attachment, instead of attaching to
+ * user-space function entry or exit.
+ *
+ * @param prog BPF program to attach
+ * @param pid Process ID to attach the uprobe to, 0 for self (own process),
+ * -1 for all processes
+ * @param binary_path Path to binary that contains provided USDT probe
+ * @param usdt_provider USDT provider name
+ * @param usdt_name USDT probe name
+ * @param opts Options for altering program attachment
+ * @return Reference to the newly created BPF link; or NULL is returned on error,
+ * error code is stored in errno
+ */
+LIBBPF_API struct bpf_link *
+bpf_program__attach_usdt(const struct bpf_program *prog,
+			 pid_t pid, const char *binary_path,
+			 const char *usdt_provider, const char *usdt_name,
+			 const struct bpf_usdt_opts *opts);
+
+struct bpf_tracepoint_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* custom user-provided value fetchable through bpf_get_attach_cookie() */
+	__u64 bpf_cookie;
+};
+#define bpf_tracepoint_opts__last_field bpf_cookie
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tracepoint(const struct bpf_program *prog,
+			       const char *tp_category,
+			       const char *tp_name);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tracepoint_opts(const struct bpf_program *prog,
+				    const char *tp_category,
+				    const char *tp_name,
+				    const struct bpf_tracepoint_opts *opts);
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,
+				   const char *tp_name);
+
+struct bpf_trace_opts {
+	/* size of this struct, for forward/backward compatibility */
+	size_t sz;
+	/* custom user-provided value fetchable through bpf_get_attach_cookie() */
+	__u64 cookie;
+};
+#define bpf_trace_opts__last_field cookie
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_trace(const struct bpf_program *prog);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_trace_opts(const struct bpf_program *prog, const struct bpf_trace_opts *opts);
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_lsm(const struct bpf_program *prog);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_cgroup(const struct bpf_program *prog, int cgroup_fd);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_netns(const struct bpf_program *prog, int netns_fd);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_xdp(const struct bpf_program *prog, int ifindex);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_freplace(const struct bpf_program *prog,
+			     int target_fd, const char *attach_func_name);
+
+struct bpf_map;
+
+LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map);
+
+struct bpf_iter_attach_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	union bpf_iter_link_info *link_info;
+	__u32 link_info_len;
+};
+#define bpf_iter_attach_opts__last_field link_info_len
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_iter(const struct bpf_program *prog,
+			 const struct bpf_iter_attach_opts *opts);
+
+LIBBPF_API enum bpf_prog_type bpf_program__type(const struct bpf_program *prog);
+
+/**
+ * @brief **bpf_program__set_type()** sets the program
+ * type of the passed BPF program.
+ * @param prog BPF program to set the program type for
+ * @param type program type to set the BPF map to have
+ * @return error code; or 0 if no error. An error occurs
+ * if the object is already loaded.
+ *
+ * This must be called before the BPF object is loaded,
+ * otherwise it has no effect and an error is returned.
+ */
+LIBBPF_API int bpf_program__set_type(struct bpf_program *prog,
+				     enum bpf_prog_type type);
+
+LIBBPF_API enum bpf_attach_type
+bpf_program__expected_attach_type(const struct bpf_program *prog);
+
+/**
+ * @brief **bpf_program__set_expected_attach_type()** sets the
+ * attach type of the passed BPF program. This is used for
+ * auto-detection of attachment when programs are loaded.
+ * @param prog BPF program to set the attach type for
+ * @param type attach type to set the BPF map to have
+ * @return error code; or 0 if no error. An error occurs
+ * if the object is already loaded.
+ *
+ * This must be called before the BPF object is loaded,
+ * otherwise it has no effect and an error is returned.
+ */
+LIBBPF_API int
+bpf_program__set_expected_attach_type(struct bpf_program *prog,
+				      enum bpf_attach_type type);
+
+LIBBPF_API __u32 bpf_program__flags(const struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_flags(struct bpf_program *prog, __u32 flags);
+
+/* Per-program log level and log buffer getters/setters.
+ * See bpf_object_open_opts comments regarding log_level and log_buf
+ * interactions.
+ */
+LIBBPF_API __u32 bpf_program__log_level(const struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_log_level(struct bpf_program *prog, __u32 log_level);
+LIBBPF_API const char *bpf_program__log_buf(const struct bpf_program *prog, size_t *log_size);
+LIBBPF_API int bpf_program__set_log_buf(struct bpf_program *prog, char *log_buf, size_t log_size);
+
+/**
+ * @brief **bpf_program__set_attach_target()** sets BTF-based attach target
+ * for supported BPF program types:
+ *   - BTF-aware raw tracepoints (tp_btf);
+ *   - fentry/fexit/fmod_ret;
+ *   - lsm;
+ *   - freplace.
+ * @param prog BPF program to set the attach type for
+ * @param type attach type to set the BPF map to have
+ * @return error code; or 0 if no error occurred.
+ */
+LIBBPF_API int
+bpf_program__set_attach_target(struct bpf_program *prog, int attach_prog_fd,
+			       const char *attach_func_name);
+
+/**
+ * @brief **bpf_object__find_map_by_name()** returns BPF map of
+ * the given name, if it exists within the passed BPF object
+ * @param obj BPF object
+ * @param name name of the BPF map
+ * @return BPF map instance, if such map exists within the BPF object;
+ * or NULL otherwise.
+ */
+LIBBPF_API struct bpf_map *
+bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name);
+
+LIBBPF_API int
+bpf_object__find_map_fd_by_name(const struct bpf_object *obj, const char *name);
+
+LIBBPF_API struct bpf_map *
+bpf_object__next_map(const struct bpf_object *obj, const struct bpf_map *map);
+
+#define bpf_object__for_each_map(pos, obj)		\
+	for ((pos) = bpf_object__next_map((obj), NULL);	\
+	     (pos) != NULL;				\
+	     (pos) = bpf_object__next_map((obj), (pos)))
+#define bpf_map__for_each bpf_object__for_each_map
+
+LIBBPF_API struct bpf_map *
+bpf_object__prev_map(const struct bpf_object *obj, const struct bpf_map *map);
+
+/**
+ * @brief **bpf_map__set_autocreate()** sets whether libbpf has to auto-create
+ * BPF map during BPF object load phase.
+ * @param map the BPF map instance
+ * @param autocreate whether to create BPF map during BPF object load
+ * @return 0 on success; -EBUSY if BPF object was already loaded
+ *
+ * **bpf_map__set_autocreate()** allows to opt-out from libbpf auto-creating
+ * BPF map. By default, libbpf will attempt to create every single BPF map
+ * defined in BPF object file using BPF_MAP_CREATE command of bpf() syscall
+ * and fill in map FD in BPF instructions.
+ *
+ * This API allows to opt-out of this process for specific map instance. This
+ * can be useful if host kernel doesn't support such BPF map type or used
+ * combination of flags and user application wants to avoid creating such
+ * a map in the first place. User is still responsible to make sure that their
+ * BPF-side code that expects to use such missing BPF map is recognized by BPF
+ * verifier as dead code, otherwise BPF verifier will reject such BPF program.
+ */
+LIBBPF_API int bpf_map__set_autocreate(struct bpf_map *map, bool autocreate);
+LIBBPF_API bool bpf_map__autocreate(const struct bpf_map *map);
+
+/**
+ * @brief **bpf_map__fd()** gets the file descriptor of the passed
+ * BPF map
+ * @param map the BPF map instance
+ * @return the file descriptor; or -EINVAL in case of an error
+ */
+LIBBPF_API int bpf_map__fd(const struct bpf_map *map);
+LIBBPF_API int bpf_map__reuse_fd(struct bpf_map *map, int fd);
+/* get map name */
+LIBBPF_API const char *bpf_map__name(const struct bpf_map *map);
+/* get/set map type */
+LIBBPF_API enum bpf_map_type bpf_map__type(const struct bpf_map *map);
+LIBBPF_API int bpf_map__set_type(struct bpf_map *map, enum bpf_map_type type);
+/* get/set map size (max_entries) */
+LIBBPF_API __u32 bpf_map__max_entries(const struct bpf_map *map);
+LIBBPF_API int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries);
+/* get/set map flags */
+LIBBPF_API __u32 bpf_map__map_flags(const struct bpf_map *map);
+LIBBPF_API int bpf_map__set_map_flags(struct bpf_map *map, __u32 flags);
+/* get/set map NUMA node */
+LIBBPF_API __u32 bpf_map__numa_node(const struct bpf_map *map);
+LIBBPF_API int bpf_map__set_numa_node(struct bpf_map *map, __u32 numa_node);
+/* get/set map key size */
+LIBBPF_API __u32 bpf_map__key_size(const struct bpf_map *map);
+LIBBPF_API int bpf_map__set_key_size(struct bpf_map *map, __u32 size);
+/* get/set map value size */
+LIBBPF_API __u32 bpf_map__value_size(const struct bpf_map *map);
+LIBBPF_API int bpf_map__set_value_size(struct bpf_map *map, __u32 size);
+/* get map key/value BTF type IDs */
+LIBBPF_API __u32 bpf_map__btf_key_type_id(const struct bpf_map *map);
+LIBBPF_API __u32 bpf_map__btf_value_type_id(const struct bpf_map *map);
+/* get/set map if_index */
+LIBBPF_API __u32 bpf_map__ifindex(const struct bpf_map *map);
+LIBBPF_API int bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex);
+/* get/set map map_extra flags */
+LIBBPF_API __u64 bpf_map__map_extra(const struct bpf_map *map);
+LIBBPF_API int bpf_map__set_map_extra(struct bpf_map *map, __u64 map_extra);
+
+LIBBPF_API int bpf_map__set_initial_value(struct bpf_map *map,
+					  const void *data, size_t size);
+LIBBPF_API const void *bpf_map__initial_value(struct bpf_map *map, size_t *psize);
+
+/**
+ * @brief **bpf_map__is_internal()** tells the caller whether or not the
+ * passed map is a special map created by libbpf automatically for things like
+ * global variables, __ksym externs, Kconfig values, etc
+ * @param map the bpf_map
+ * @return true, if the map is an internal map; false, otherwise
+ */
+LIBBPF_API bool bpf_map__is_internal(const struct bpf_map *map);
+LIBBPF_API int bpf_map__set_pin_path(struct bpf_map *map, const char *path);
+LIBBPF_API const char *bpf_map__pin_path(const struct bpf_map *map);
+LIBBPF_API bool bpf_map__is_pinned(const struct bpf_map *map);
+LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path);
+LIBBPF_API int bpf_map__unpin(struct bpf_map *map, const char *path);
+
+LIBBPF_API int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd);
+LIBBPF_API struct bpf_map *bpf_map__inner_map(struct bpf_map *map);
+
+/**
+ * @brief **bpf_map__lookup_elem()** allows to lookup BPF map value
+ * corresponding to provided key.
+ * @param map BPF map to lookup element in
+ * @param key pointer to memory containing bytes of the key used for lookup
+ * @param key_sz size in bytes of key data, needs to match BPF map definition's **key_size**
+ * @param value pointer to memory in which looked up value will be stored
+ * @param value_sz size in byte of value data memory; it has to match BPF map
+ * definition's **value_size**. For per-CPU BPF maps value size has to be
+ * a product of BPF map value size and number of possible CPUs in the system
+ * (could be fetched with **libbpf_num_possible_cpus()**). Note also that for
+ * per-CPU values value size has to be aligned up to closest 8 bytes for
+ * alignment reasons, so expected size is: `round_up(value_size, 8)
+ * * libbpf_num_possible_cpus()`.
+ * @flags extra flags passed to kernel for this operation
+ * @return 0, on success; negative error, otherwise
+ *
+ * **bpf_map__lookup_elem()** is high-level equivalent of
+ * **bpf_map_lookup_elem()** API with added check for key and value size.
+ */
+LIBBPF_API int bpf_map__lookup_elem(const struct bpf_map *map,
+				    const void *key, size_t key_sz,
+				    void *value, size_t value_sz, __u64 flags);
+
+/**
+ * @brief **bpf_map__update_elem()** allows to insert or update value in BPF
+ * map that corresponds to provided key.
+ * @param map BPF map to insert to or update element in
+ * @param key pointer to memory containing bytes of the key
+ * @param key_sz size in bytes of key data, needs to match BPF map definition's **key_size**
+ * @param value pointer to memory containing bytes of the value
+ * @param value_sz size in byte of value data memory; it has to match BPF map
+ * definition's **value_size**. For per-CPU BPF maps value size has to be
+ * a product of BPF map value size and number of possible CPUs in the system
+ * (could be fetched with **libbpf_num_possible_cpus()**). Note also that for
+ * per-CPU values value size has to be aligned up to closest 8 bytes for
+ * alignment reasons, so expected size is: `round_up(value_size, 8)
+ * * libbpf_num_possible_cpus()`.
+ * @flags extra flags passed to kernel for this operation
+ * @return 0, on success; negative error, otherwise
+ *
+ * **bpf_map__update_elem()** is high-level equivalent of
+ * **bpf_map_update_elem()** API with added check for key and value size.
+ */
+LIBBPF_API int bpf_map__update_elem(const struct bpf_map *map,
+				    const void *key, size_t key_sz,
+				    const void *value, size_t value_sz, __u64 flags);
+
+/**
+ * @brief **bpf_map__delete_elem()** allows to delete element in BPF map that
+ * corresponds to provided key.
+ * @param map BPF map to delete element from
+ * @param key pointer to memory containing bytes of the key
+ * @param key_sz size in bytes of key data, needs to match BPF map definition's **key_size**
+ * @flags extra flags passed to kernel for this operation
+ * @return 0, on success; negative error, otherwise
+ *
+ * **bpf_map__delete_elem()** is high-level equivalent of
+ * **bpf_map_delete_elem()** API with added check for key size.
+ */
+LIBBPF_API int bpf_map__delete_elem(const struct bpf_map *map,
+				    const void *key, size_t key_sz, __u64 flags);
+
+/**
+ * @brief **bpf_map__lookup_and_delete_elem()** allows to lookup BPF map value
+ * corresponding to provided key and atomically delete it afterwards.
+ * @param map BPF map to lookup element in
+ * @param key pointer to memory containing bytes of the key used for lookup
+ * @param key_sz size in bytes of key data, needs to match BPF map definition's **key_size**
+ * @param value pointer to memory in which looked up value will be stored
+ * @param value_sz size in byte of value data memory; it has to match BPF map
+ * definition's **value_size**. For per-CPU BPF maps value size has to be
+ * a product of BPF map value size and number of possible CPUs in the system
+ * (could be fetched with **libbpf_num_possible_cpus()**). Note also that for
+ * per-CPU values value size has to be aligned up to closest 8 bytes for
+ * alignment reasons, so expected size is: `round_up(value_size, 8)
+ * * libbpf_num_possible_cpus()`.
+ * @flags extra flags passed to kernel for this operation
+ * @return 0, on success; negative error, otherwise
+ *
+ * **bpf_map__lookup_and_delete_elem()** is high-level equivalent of
+ * **bpf_map_lookup_and_delete_elem()** API with added check for key and value size.
+ */
+LIBBPF_API int bpf_map__lookup_and_delete_elem(const struct bpf_map *map,
+					       const void *key, size_t key_sz,
+					       void *value, size_t value_sz, __u64 flags);
+
+/**
+ * @brief **bpf_map__get_next_key()** allows to iterate BPF map keys by
+ * fetching next key that follows current key.
+ * @param map BPF map to fetch next key from
+ * @param cur_key pointer to memory containing bytes of current key or NULL to
+ * fetch the first key
+ * @param next_key pointer to memory to write next key into
+ * @param key_sz size in bytes of key data, needs to match BPF map definition's **key_size**
+ * @return 0, on success; -ENOENT if **cur_key** is the last key in BPF map;
+ * negative error, otherwise
+ *
+ * **bpf_map__get_next_key()** is high-level equivalent of
+ * **bpf_map_get_next_key()** API with added check for key size.
+ */
+LIBBPF_API int bpf_map__get_next_key(const struct bpf_map *map,
+				     const void *cur_key, void *next_key, size_t key_sz);
+
+struct bpf_xdp_set_link_opts {
+	size_t sz;
+	int old_fd;
+	size_t :0;
+};
+#define bpf_xdp_set_link_opts__last_field old_fd
+
+struct bpf_xdp_attach_opts {
+	size_t sz;
+	int old_prog_fd;
+	size_t :0;
+};
+#define bpf_xdp_attach_opts__last_field old_prog_fd
+
+struct bpf_xdp_query_opts {
+	size_t sz;
+	__u32 prog_id;		/* output */
+	__u32 drv_prog_id;	/* output */
+	__u32 hw_prog_id;	/* output */
+	__u32 skb_prog_id;	/* output */
+	__u8 attach_mode;	/* output */
+	size_t :0;
+};
+#define bpf_xdp_query_opts__last_field attach_mode
+
+LIBBPF_API int bpf_xdp_attach(int ifindex, int prog_fd, __u32 flags,
+			      const struct bpf_xdp_attach_opts *opts);
+LIBBPF_API int bpf_xdp_detach(int ifindex, __u32 flags,
+			      const struct bpf_xdp_attach_opts *opts);
+LIBBPF_API int bpf_xdp_query(int ifindex, int flags, struct bpf_xdp_query_opts *opts);
+LIBBPF_API int bpf_xdp_query_id(int ifindex, int flags, __u32 *prog_id);
+
+/* TC related API */
+enum bpf_tc_attach_point {
+	BPF_TC_INGRESS = 1 << 0,
+	BPF_TC_EGRESS  = 1 << 1,
+	BPF_TC_CUSTOM  = 1 << 2,
+};
+
+#define BPF_TC_PARENT(a, b) 	\
+	((((a) << 16) & 0xFFFF0000U) | ((b) & 0x0000FFFFU))
+
+enum bpf_tc_flags {
+	BPF_TC_F_REPLACE = 1 << 0,
+};
+
+struct bpf_tc_hook {
+	size_t sz;
+	int ifindex;
+	enum bpf_tc_attach_point attach_point;
+	__u32 parent;
+	size_t :0;
+};
+#define bpf_tc_hook__last_field parent
+
+struct bpf_tc_opts {
+	size_t sz;
+	int prog_fd;
+	__u32 flags;
+	__u32 prog_id;
+	__u32 handle;
+	__u32 priority;
+	size_t :0;
+};
+#define bpf_tc_opts__last_field priority
+
+LIBBPF_API int bpf_tc_hook_create(struct bpf_tc_hook *hook);
+LIBBPF_API int bpf_tc_hook_destroy(struct bpf_tc_hook *hook);
+LIBBPF_API int bpf_tc_attach(const struct bpf_tc_hook *hook,
+			     struct bpf_tc_opts *opts);
+LIBBPF_API int bpf_tc_detach(const struct bpf_tc_hook *hook,
+			     const struct bpf_tc_opts *opts);
+LIBBPF_API int bpf_tc_query(const struct bpf_tc_hook *hook,
+			    struct bpf_tc_opts *opts);
+
+/* Ring buffer APIs */
+struct ring_buffer;
+struct user_ring_buffer;
+
+typedef int (*ring_buffer_sample_fn)(void *ctx, void *data, size_t size);
+
+struct ring_buffer_opts {
+	size_t sz; /* size of this struct, for forward/backward compatiblity */
+};
+
+#define ring_buffer_opts__last_field sz
+
+LIBBPF_API struct ring_buffer *
+ring_buffer__new(int map_fd, ring_buffer_sample_fn sample_cb, void *ctx,
+		 const struct ring_buffer_opts *opts);
+LIBBPF_API void ring_buffer__free(struct ring_buffer *rb);
+LIBBPF_API int ring_buffer__add(struct ring_buffer *rb, int map_fd,
+				ring_buffer_sample_fn sample_cb, void *ctx);
+LIBBPF_API int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms);
+LIBBPF_API int ring_buffer__consume(struct ring_buffer *rb);
+LIBBPF_API int ring_buffer__epoll_fd(const struct ring_buffer *rb);
+
+struct user_ring_buffer_opts {
+	size_t sz; /* size of this struct, for forward/backward compatibility */
+};
+
+#define user_ring_buffer_opts__last_field sz
+
+/* @brief **user_ring_buffer__new()** creates a new instance of a user ring
+ * buffer.
+ *
+ * @param map_fd A file descriptor to a BPF_MAP_TYPE_USER_RINGBUF map.
+ * @param opts Options for how the ring buffer should be created.
+ * @return A user ring buffer on success; NULL and errno being set on a
+ * failure.
+ */
+LIBBPF_API struct user_ring_buffer *
+user_ring_buffer__new(int map_fd, const struct user_ring_buffer_opts *opts);
+
+/* @brief **user_ring_buffer__reserve()** reserves a pointer to a sample in the
+ * user ring buffer.
+ * @param rb A pointer to a user ring buffer.
+ * @param size The size of the sample, in bytes.
+ * @return A pointer to an 8-byte aligned reserved region of the user ring
+ * buffer; NULL, and errno being set if a sample could not be reserved.
+ *
+ * This function is *not* thread safe, and callers must synchronize accessing
+ * this function if there are multiple producers.  If a size is requested that
+ * is larger than the size of the entire ring buffer, errno will be set to
+ * E2BIG and NULL is returned. If the ring buffer could accommodate the size,
+ * but currently does not have enough space, errno is set to ENOSPC and NULL is
+ * returned.
+ *
+ * After initializing the sample, callers must invoke
+ * **user_ring_buffer__submit()** to post the sample to the kernel. Otherwise,
+ * the sample must be freed with **user_ring_buffer__discard()**.
+ */
+LIBBPF_API void *user_ring_buffer__reserve(struct user_ring_buffer *rb, __u32 size);
+
+/* @brief **user_ring_buffer__reserve_blocking()** reserves a record in the
+ * ring buffer, possibly blocking for up to @timeout_ms until a sample becomes
+ * available.
+ * @param rb The user ring buffer.
+ * @param size The size of the sample, in bytes.
+ * @param timeout_ms The amount of time, in milliseconds, for which the caller
+ * should block when waiting for a sample. -1 causes the caller to block
+ * indefinitely.
+ * @return A pointer to an 8-byte aligned reserved region of the user ring
+ * buffer; NULL, and errno being set if a sample could not be reserved.
+ *
+ * This function is *not* thread safe, and callers must synchronize
+ * accessing this function if there are multiple producers
+ *
+ * If **timeout_ms** is -1, the function will block indefinitely until a sample
+ * becomes available. Otherwise, **timeout_ms** must be non-negative, or errno
+ * is set to EINVAL, and NULL is returned. If **timeout_ms** is 0, no blocking
+ * will occur and the function will return immediately after attempting to
+ * reserve a sample.
+ *
+ * If **size** is larger than the size of the entire ring buffer, errno is set
+ * to E2BIG and NULL is returned. If the ring buffer could accommodate
+ * **size**, but currently does not have enough space, the caller will block
+ * until at most **timeout_ms** has elapsed. If insufficient space is available
+ * at that time, errno is set to ENOSPC, and NULL is returned.
+ *
+ * The kernel guarantees that it will wake up this thread to check if
+ * sufficient space is available in the ring buffer at least once per
+ * invocation of the **bpf_ringbuf_drain()** helper function, provided that at
+ * least one sample is consumed, and the BPF program did not invoke the
+ * function with BPF_RB_NO_WAKEUP. A wakeup may occur sooner than that, but the
+ * kernel does not guarantee this. If the helper function is invoked with
+ * BPF_RB_FORCE_WAKEUP, a wakeup event will be sent even if no sample is
+ * consumed.
+ *
+ * When a sample of size **size** is found within **timeout_ms**, a pointer to
+ * the sample is returned. After initializing the sample, callers must invoke
+ * **user_ring_buffer__submit()** to post the sample to the ring buffer.
+ * Otherwise, the sample must be freed with **user_ring_buffer__discard()**.
+ */
+LIBBPF_API void *user_ring_buffer__reserve_blocking(struct user_ring_buffer *rb,
+						    __u32 size,
+						    int timeout_ms);
+
+/* @brief **user_ring_buffer__submit()** submits a previously reserved sample
+ * into the ring buffer.
+ * @param rb The user ring buffer.
+ * @param sample A reserved sample.
+ *
+ * It is not necessary to synchronize amongst multiple producers when invoking
+ * this function.
+ */
+LIBBPF_API void user_ring_buffer__submit(struct user_ring_buffer *rb, void *sample);
+
+/* @brief **user_ring_buffer__discard()** discards a previously reserved sample.
+ * @param rb The user ring buffer.
+ * @param sample A reserved sample.
+ *
+ * It is not necessary to synchronize amongst multiple producers when invoking
+ * this function.
+ */
+LIBBPF_API void user_ring_buffer__discard(struct user_ring_buffer *rb, void *sample);
+
+/* @brief **user_ring_buffer__free()** frees a ring buffer that was previously
+ * created with **user_ring_buffer__new()**.
+ * @param rb The user ring buffer being freed.
+ */
+LIBBPF_API void user_ring_buffer__free(struct user_ring_buffer *rb);
+
+/* Perf buffer APIs */
+struct perf_buffer;
+
+typedef void (*perf_buffer_sample_fn)(void *ctx, int cpu,
+				      void *data, __u32 size);
+typedef void (*perf_buffer_lost_fn)(void *ctx, int cpu, __u64 cnt);
+
+/* common use perf buffer options */
+struct perf_buffer_opts {
+	size_t sz;
+};
+#define perf_buffer_opts__last_field sz
+
+/**
+ * @brief **perf_buffer__new()** creates BPF perfbuf manager for a specified
+ * BPF_PERF_EVENT_ARRAY map
+ * @param map_fd FD of BPF_PERF_EVENT_ARRAY BPF map that will be used by BPF
+ * code to send data over to user-space
+ * @param page_cnt number of memory pages allocated for each per-CPU buffer
+ * @param sample_cb function called on each received data record
+ * @param lost_cb function called when record loss has occurred
+ * @param ctx user-provided extra context passed into *sample_cb* and *lost_cb*
+ * @return a new instance of struct perf_buffer on success, NULL on error with
+ * *errno* containing an error code
+ */
+LIBBPF_API struct perf_buffer *
+perf_buffer__new(int map_fd, size_t page_cnt,
+		 perf_buffer_sample_fn sample_cb, perf_buffer_lost_fn lost_cb, void *ctx,
+		 const struct perf_buffer_opts *opts);
+
+enum bpf_perf_event_ret {
+	LIBBPF_PERF_EVENT_DONE	= 0,
+	LIBBPF_PERF_EVENT_ERROR	= -1,
+	LIBBPF_PERF_EVENT_CONT	= -2,
+};
+
+struct perf_event_header;
+
+typedef enum bpf_perf_event_ret
+(*perf_buffer_event_fn)(void *ctx, int cpu, struct perf_event_header *event);
+
+/* raw perf buffer options, giving most power and control */
+struct perf_buffer_raw_opts {
+	size_t sz;
+	long :0;
+	long :0;
+	/* if cpu_cnt == 0, open all on all possible CPUs (up to the number of
+	 * max_entries of given PERF_EVENT_ARRAY map)
+	 */
+	int cpu_cnt;
+	/* if cpu_cnt > 0, cpus is an array of CPUs to open ring buffers on */
+	int *cpus;
+	/* if cpu_cnt > 0, map_keys specify map keys to set per-CPU FDs for */
+	int *map_keys;
+};
+#define perf_buffer_raw_opts__last_field map_keys
+
+struct perf_event_attr;
+
+LIBBPF_API struct perf_buffer *
+perf_buffer__new_raw(int map_fd, size_t page_cnt, struct perf_event_attr *attr,
+		     perf_buffer_event_fn event_cb, void *ctx,
+		     const struct perf_buffer_raw_opts *opts);
+
+LIBBPF_API void perf_buffer__free(struct perf_buffer *pb);
+LIBBPF_API int perf_buffer__epoll_fd(const struct perf_buffer *pb);
+LIBBPF_API int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms);
+LIBBPF_API int perf_buffer__consume(struct perf_buffer *pb);
+LIBBPF_API int perf_buffer__consume_buffer(struct perf_buffer *pb, size_t buf_idx);
+LIBBPF_API size_t perf_buffer__buffer_cnt(const struct perf_buffer *pb);
+LIBBPF_API int perf_buffer__buffer_fd(const struct perf_buffer *pb, size_t buf_idx);
+/**
+ * @brief **perf_buffer__buffer()** returns the per-cpu raw mmap()'ed underlying
+ * memory region of the ring buffer.
+ * This ring buffer can be used to implement a custom events consumer.
+ * The ring buffer starts with the *struct perf_event_mmap_page*, which
+ * holds the ring buffer managment fields, when accessing the header
+ * structure it's important to be SMP aware.
+ * You can refer to *perf_event_read_simple* for a simple example.
+ * @param pb the perf buffer structure
+ * @param buf_idx the buffer index to retreive
+ * @param buf (out) gets the base pointer of the mmap()'ed memory
+ * @param buf_size (out) gets the size of the mmap()'ed region
+ * @return 0 on success, negative error code for failure
+ */
+LIBBPF_API int perf_buffer__buffer(struct perf_buffer *pb, int buf_idx, void **buf,
+				   size_t *buf_size);
+
+struct bpf_prog_linfo;
+struct bpf_prog_info;
+
+LIBBPF_API void bpf_prog_linfo__free(struct bpf_prog_linfo *prog_linfo);
+LIBBPF_API struct bpf_prog_linfo *
+bpf_prog_linfo__new(const struct bpf_prog_info *info);
+LIBBPF_API const struct bpf_line_info *
+bpf_prog_linfo__lfind_addr_func(const struct bpf_prog_linfo *prog_linfo,
+				__u64 addr, __u32 func_idx, __u32 nr_skip);
+LIBBPF_API const struct bpf_line_info *
+bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
+		      __u32 insn_off, __u32 nr_skip);
+
+/*
+ * Probe for supported system features
+ *
+ * Note that running many of these probes in a short amount of time can cause
+ * the kernel to reach the maximal size of lockable memory allowed for the
+ * user, causing subsequent probes to fail. In this case, the caller may want
+ * to adjust that limit with setrlimit().
+ */
+
+/**
+ * @brief **libbpf_probe_bpf_prog_type()** detects if host kernel supports
+ * BPF programs of a given type.
+ * @param prog_type BPF program type to detect kernel support for
+ * @param opts reserved for future extensibility, should be NULL
+ * @return 1, if given program type is supported; 0, if given program type is
+ * not supported; negative error code if feature detection failed or can't be
+ * performed
+ *
+ * Make sure the process has required set of CAP_* permissions (or runs as
+ * root) when performing feature checking.
+ */
+LIBBPF_API int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts);
+/**
+ * @brief **libbpf_probe_bpf_map_type()** detects if host kernel supports
+ * BPF maps of a given type.
+ * @param map_type BPF map type to detect kernel support for
+ * @param opts reserved for future extensibility, should be NULL
+ * @return 1, if given map type is supported; 0, if given map type is
+ * not supported; negative error code if feature detection failed or can't be
+ * performed
+ *
+ * Make sure the process has required set of CAP_* permissions (or runs as
+ * root) when performing feature checking.
+ */
+LIBBPF_API int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts);
+/**
+ * @brief **libbpf_probe_bpf_helper()** detects if host kernel supports the
+ * use of a given BPF helper from specified BPF program type.
+ * @param prog_type BPF program type used to check the support of BPF helper
+ * @param helper_id BPF helper ID (enum bpf_func_id) to check support for
+ * @param opts reserved for future extensibility, should be NULL
+ * @return 1, if given combination of program type and helper is supported; 0,
+ * if the combination is not supported; negative error code if feature
+ * detection for provided input arguments failed or can't be performed
+ *
+ * Make sure the process has required set of CAP_* permissions (or runs as
+ * root) when performing feature checking.
+ */
+LIBBPF_API int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type,
+				       enum bpf_func_id helper_id, const void *opts);
+
+/**
+ * @brief **libbpf_num_possible_cpus()** is a helper function to get the
+ * number of possible CPUs that the host kernel supports and expects.
+ * @return number of possible CPUs; or error code on failure
+ *
+ * Example usage:
+ *
+ *     int ncpus = libbpf_num_possible_cpus();
+ *     if (ncpus < 0) {
+ *          // error handling
+ *     }
+ *     long values[ncpus];
+ *     bpf_map_lookup_elem(per_cpu_map_fd, key, values);
+ */
+LIBBPF_API int libbpf_num_possible_cpus(void);
+
+struct bpf_map_skeleton {
+	const char *name;
+	struct bpf_map **map;
+	void **mmaped;
+};
+
+struct bpf_prog_skeleton {
+	const char *name;
+	struct bpf_program **prog;
+	struct bpf_link **link;
+};
+
+struct bpf_object_skeleton {
+	size_t sz; /* size of this struct, for forward/backward compatibility */
+
+	const char *name;
+	const void *data;
+	size_t data_sz;
+
+	struct bpf_object **obj;
+
+	int map_cnt;
+	int map_skel_sz; /* sizeof(struct bpf_map_skeleton) */
+	struct bpf_map_skeleton *maps;
+
+	int prog_cnt;
+	int prog_skel_sz; /* sizeof(struct bpf_prog_skeleton) */
+	struct bpf_prog_skeleton *progs;
+};
+
+LIBBPF_API int
+bpf_object__open_skeleton(struct bpf_object_skeleton *s,
+			  const struct bpf_object_open_opts *opts);
+LIBBPF_API int bpf_object__load_skeleton(struct bpf_object_skeleton *s);
+LIBBPF_API int bpf_object__attach_skeleton(struct bpf_object_skeleton *s);
+LIBBPF_API void bpf_object__detach_skeleton(struct bpf_object_skeleton *s);
+LIBBPF_API void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s);
+
+struct bpf_var_skeleton {
+	const char *name;
+	struct bpf_map **map;
+	void **addr;
+};
+
+struct bpf_object_subskeleton {
+	size_t sz; /* size of this struct, for forward/backward compatibility */
+
+	const struct bpf_object *obj;
+
+	int map_cnt;
+	int map_skel_sz; /* sizeof(struct bpf_map_skeleton) */
+	struct bpf_map_skeleton *maps;
+
+	int prog_cnt;
+	int prog_skel_sz; /* sizeof(struct bpf_prog_skeleton) */
+	struct bpf_prog_skeleton *progs;
+
+	int var_cnt;
+	int var_skel_sz; /* sizeof(struct bpf_var_skeleton) */
+	struct bpf_var_skeleton *vars;
+};
+
+LIBBPF_API int
+bpf_object__open_subskeleton(struct bpf_object_subskeleton *s);
+LIBBPF_API void
+bpf_object__destroy_subskeleton(struct bpf_object_subskeleton *s);
+
+struct gen_loader_opts {
+	size_t sz; /* size of this struct, for forward/backward compatiblity */
+	const char *data;
+	const char *insns;
+	__u32 data_sz;
+	__u32 insns_sz;
+};
+
+#define gen_loader_opts__last_field insns_sz
+LIBBPF_API int bpf_object__gen_loader(struct bpf_object *obj,
+				      struct gen_loader_opts *opts);
+
+enum libbpf_tristate {
+	TRI_NO = 0,
+	TRI_YES = 1,
+	TRI_MODULE = 2,
+};
+
+struct bpf_linker_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+};
+#define bpf_linker_opts__last_field sz
+
+struct bpf_linker_file_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+};
+#define bpf_linker_file_opts__last_field sz
+
+struct bpf_linker;
+
+LIBBPF_API struct bpf_linker *bpf_linker__new(const char *filename, struct bpf_linker_opts *opts);
+LIBBPF_API int bpf_linker__add_file(struct bpf_linker *linker,
+				    const char *filename,
+				    const struct bpf_linker_file_opts *opts);
+LIBBPF_API int bpf_linker__finalize(struct bpf_linker *linker);
+LIBBPF_API void bpf_linker__free(struct bpf_linker *linker);
+
+/*
+ * Custom handling of BPF program's SEC() definitions
+ */
+
+struct bpf_prog_load_opts; /* defined in bpf.h */
+
+/* Called during bpf_object__open() for each recognized BPF program. Callback
+ * can use various bpf_program__set_*() setters to adjust whatever properties
+ * are necessary.
+ */
+typedef int (*libbpf_prog_setup_fn_t)(struct bpf_program *prog, long cookie);
+
+/* Called right before libbpf performs bpf_prog_load() to load BPF program
+ * into the kernel. Callback can adjust opts as necessary.
+ */
+typedef int (*libbpf_prog_prepare_load_fn_t)(struct bpf_program *prog,
+					     struct bpf_prog_load_opts *opts, long cookie);
+
+/* Called during skeleton attach or through bpf_program__attach(). If
+ * auto-attach is not supported, callback should return 0 and set link to
+ * NULL (it's not considered an error during skeleton attach, but it will be
+ * an error for bpf_program__attach() calls). On error, error should be
+ * returned directly and link set to NULL. On success, return 0 and set link
+ * to a valid struct bpf_link.
+ */
+typedef int (*libbpf_prog_attach_fn_t)(const struct bpf_program *prog, long cookie,
+				       struct bpf_link **link);
+
+struct libbpf_prog_handler_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* User-provided value that is passed to prog_setup_fn,
+	 * prog_prepare_load_fn, and prog_attach_fn callbacks. Allows user to
+	 * register one set of callbacks for multiple SEC() definitions and
+	 * still be able to distinguish them, if necessary. For example,
+	 * libbpf itself is using this to pass necessary flags (e.g.,
+	 * sleepable flag) to a common internal SEC() handler.
+	 */
+	long cookie;
+	/* BPF program initialization callback (see libbpf_prog_setup_fn_t).
+	 * Callback is optional, pass NULL if it's not necessary.
+	 */
+	libbpf_prog_setup_fn_t prog_setup_fn;
+	/* BPF program loading callback (see libbpf_prog_prepare_load_fn_t).
+	 * Callback is optional, pass NULL if it's not necessary.
+	 */
+	libbpf_prog_prepare_load_fn_t prog_prepare_load_fn;
+	/* BPF program attach callback (see libbpf_prog_attach_fn_t).
+	 * Callback is optional, pass NULL if it's not necessary.
+	 */
+	libbpf_prog_attach_fn_t prog_attach_fn;
+};
+#define libbpf_prog_handler_opts__last_field prog_attach_fn
+
+/**
+ * @brief **libbpf_register_prog_handler()** registers a custom BPF program
+ * SEC() handler.
+ * @param sec section prefix for which custom handler is registered
+ * @param prog_type BPF program type associated with specified section
+ * @param exp_attach_type Expected BPF attach type associated with specified section
+ * @param opts optional cookie, callbacks, and other extra options
+ * @return Non-negative handler ID is returned on success. This handler ID has
+ * to be passed to *libbpf_unregister_prog_handler()* to unregister such
+ * custom handler. Negative error code is returned on error.
+ *
+ * *sec* defines which SEC() definitions are handled by this custom handler
+ * registration. *sec* can have few different forms:
+ *   - if *sec* is just a plain string (e.g., "abc"), it will match only
+ *   SEC("abc"). If BPF program specifies SEC("abc/whatever") it will result
+ *   in an error;
+ *   - if *sec* is of the form "abc/", proper SEC() form is
+ *   SEC("abc/something"), where acceptable "something" should be checked by
+ *   *prog_init_fn* callback, if there are additional restrictions;
+ *   - if *sec* is of the form "abc+", it will successfully match both
+ *   SEC("abc") and SEC("abc/whatever") forms;
+ *   - if *sec* is NULL, custom handler is registered for any BPF program that
+ *   doesn't match any of the registered (custom or libbpf's own) SEC()
+ *   handlers. There could be only one such generic custom handler registered
+ *   at any given time.
+ *
+ * All custom handlers (except the one with *sec* == NULL) are processed
+ * before libbpf's own SEC() handlers. It is allowed to "override" libbpf's
+ * SEC() handlers by registering custom ones for the same section prefix
+ * (i.e., it's possible to have custom SEC("perf_event/LLC-load-misses")
+ * handler).
+ *
+ * Note, like much of global libbpf APIs (e.g., libbpf_set_print(),
+ * libbpf_set_strict_mode(), etc)) these APIs are not thread-safe. User needs
+ * to ensure synchronization if there is a risk of running this API from
+ * multiple threads simultaneously.
+ */
+LIBBPF_API int libbpf_register_prog_handler(const char *sec,
+					    enum bpf_prog_type prog_type,
+					    enum bpf_attach_type exp_attach_type,
+					    const struct libbpf_prog_handler_opts *opts);
+/**
+ * @brief *libbpf_unregister_prog_handler()* unregisters previously registered
+ * custom BPF program SEC() handler.
+ * @param handler_id handler ID returned by *libbpf_register_prog_handler()*
+ * after successful registration
+ * @return 0 on success, negative error code if handler isn't found
+ *
+ * Note, like much of global libbpf APIs (e.g., libbpf_set_print(),
+ * libbpf_set_strict_mode(), etc)) these APIs are not thread-safe. User needs
+ * to ensure synchronization if there is a risk of running this API from
+ * multiple threads simultaneously.
+ */
+LIBBPF_API int libbpf_unregister_prog_handler(int handler_id);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* __LIBBPF_LIBBPF_H */
diff --git a/src/libbpf.map b/src/libbpf.map
new file mode 100644
index 0000000..71bf569
--- /dev/null
+++ b/src/libbpf.map
@@ -0,0 +1,384 @@
+LIBBPF_0.0.1 {
+	global:
+		bpf_btf_get_fd_by_id;
+		bpf_map__btf_key_type_id;
+		bpf_map__btf_value_type_id;
+		bpf_map__fd;
+		bpf_map__name;
+		bpf_map__pin;
+		bpf_map__reuse_fd;
+		bpf_map__set_ifindex;
+		bpf_map__set_inner_map_fd;
+		bpf_map__unpin;
+		bpf_map_delete_elem;
+		bpf_map_get_fd_by_id;
+		bpf_map_get_next_id;
+		bpf_map_get_next_key;
+		bpf_map_lookup_and_delete_elem;
+		bpf_map_lookup_elem;
+		bpf_map_update_elem;
+		bpf_obj_get;
+		bpf_obj_get_info_by_fd;
+		bpf_obj_pin;
+		bpf_object__btf_fd;
+		bpf_object__close;
+		bpf_object__find_map_by_name;
+		bpf_object__kversion;
+		bpf_object__load;
+		bpf_object__name;
+		bpf_object__open;
+		bpf_object__pin;
+		bpf_object__pin_maps;
+		bpf_object__pin_programs;
+		bpf_object__unpin_maps;
+		bpf_object__unpin_programs;
+		bpf_prog_attach;
+		bpf_prog_detach;
+		bpf_prog_detach2;
+		bpf_prog_get_fd_by_id;
+		bpf_prog_get_next_id;
+		bpf_prog_query;
+		bpf_program__fd;
+		bpf_program__pin;
+		bpf_program__set_expected_attach_type;
+		bpf_program__set_ifindex;
+		bpf_program__set_type;
+		bpf_program__unload;
+		bpf_program__unpin;
+		bpf_prog_linfo__free;
+		bpf_prog_linfo__new;
+		bpf_prog_linfo__lfind_addr_func;
+		bpf_prog_linfo__lfind;
+		bpf_raw_tracepoint_open;
+		bpf_task_fd_query;
+		btf__fd;
+		btf__find_by_name;
+		btf__free;
+		btf__name_by_offset;
+		btf__new;
+		btf__resolve_size;
+		btf__resolve_type;
+		btf__type_by_id;
+		libbpf_attach_type_by_name;
+		libbpf_get_error;
+		libbpf_prog_type_by_name;
+		libbpf_set_print;
+		libbpf_strerror;
+	local:
+		*;
+};
+
+LIBBPF_0.0.2 {
+	global:
+		bpf_map_lookup_elem_flags;
+		bpf_object__btf;
+		bpf_object__find_map_fd_by_name;
+		btf__get_raw_data;
+		btf_ext__free;
+		btf_ext__get_raw_data;
+		btf_ext__new;
+} LIBBPF_0.0.1;
+
+LIBBPF_0.0.3 {
+	global:
+		bpf_map__is_internal;
+		bpf_map_freeze;
+} LIBBPF_0.0.2;
+
+LIBBPF_0.0.4 {
+	global:
+		bpf_link__destroy;
+		bpf_program__attach_kprobe;
+		bpf_program__attach_perf_event;
+		bpf_program__attach_raw_tracepoint;
+		bpf_program__attach_tracepoint;
+		bpf_program__attach_uprobe;
+		btf_dump__dump_type;
+		btf_dump__free;
+		btf__parse_elf;
+		libbpf_num_possible_cpus;
+		perf_buffer__free;
+		perf_buffer__poll;
+} LIBBPF_0.0.3;
+
+LIBBPF_0.0.5 {
+	global:
+		bpf_btf_get_next_id;
+} LIBBPF_0.0.4;
+
+LIBBPF_0.0.6 {
+	global:
+		bpf_map__get_pin_path;
+		bpf_map__is_pinned;
+		bpf_map__set_pin_path;
+		bpf_object__open_file;
+		bpf_object__open_mem;
+		bpf_program__attach_trace;
+		bpf_program__get_expected_attach_type;
+		bpf_program__get_type;
+		btf__find_by_name_kind;
+		libbpf_find_vmlinux_btf_id;
+} LIBBPF_0.0.5;
+
+LIBBPF_0.0.7 {
+	global:
+		btf_dump__emit_type_decl;
+		bpf_link__disconnect;
+		bpf_map__attach_struct_ops;
+		bpf_map_delete_batch;
+		bpf_map_lookup_and_delete_batch;
+		bpf_map_lookup_batch;
+		bpf_map_update_batch;
+		bpf_object__find_program_by_name;
+		bpf_object__attach_skeleton;
+		bpf_object__destroy_skeleton;
+		bpf_object__detach_skeleton;
+		bpf_object__load_skeleton;
+		bpf_object__open_skeleton;
+		bpf_program__attach;
+		bpf_program__name;
+		btf__align_of;
+		libbpf_find_kernel_btf;
+} LIBBPF_0.0.6;
+
+LIBBPF_0.0.8 {
+	global:
+		bpf_link__fd;
+		bpf_link__open;
+		bpf_link__pin;
+		bpf_link__pin_path;
+		bpf_link__unpin;
+		bpf_link__update_program;
+		bpf_link_create;
+		bpf_link_update;
+		bpf_map__set_initial_value;
+		bpf_prog_attach_opts;
+		bpf_program__attach_cgroup;
+		bpf_program__attach_lsm;
+		bpf_program__set_attach_target;
+} LIBBPF_0.0.7;
+
+LIBBPF_0.0.9 {
+	global:
+		bpf_enable_stats;
+		bpf_iter_create;
+		bpf_link_get_fd_by_id;
+		bpf_link_get_next_id;
+		bpf_program__attach_iter;
+		bpf_program__attach_netns;
+		perf_buffer__consume;
+		ring_buffer__add;
+		ring_buffer__consume;
+		ring_buffer__free;
+		ring_buffer__new;
+		ring_buffer__poll;
+} LIBBPF_0.0.8;
+
+LIBBPF_0.1.0 {
+	global:
+		bpf_link__detach;
+		bpf_link_detach;
+		bpf_map__ifindex;
+		bpf_map__key_size;
+		bpf_map__map_flags;
+		bpf_map__max_entries;
+		bpf_map__numa_node;
+		bpf_map__set_key_size;
+		bpf_map__set_map_flags;
+		bpf_map__set_max_entries;
+		bpf_map__set_numa_node;
+		bpf_map__set_type;
+		bpf_map__set_value_size;
+		bpf_map__type;
+		bpf_map__value_size;
+		bpf_program__attach_xdp;
+		bpf_program__autoload;
+		bpf_program__set_autoload;
+		btf__parse;
+		btf__parse_raw;
+		btf__pointer_size;
+		btf__set_fd;
+		btf__set_pointer_size;
+} LIBBPF_0.0.9;
+
+LIBBPF_0.2.0 {
+	global:
+		bpf_prog_bind_map;
+		bpf_prog_test_run_opts;
+		bpf_program__attach_freplace;
+		bpf_program__section_name;
+		btf__add_array;
+		btf__add_const;
+		btf__add_enum;
+		btf__add_enum_value;
+		btf__add_datasec;
+		btf__add_datasec_var_info;
+		btf__add_field;
+		btf__add_func;
+		btf__add_func_param;
+		btf__add_func_proto;
+		btf__add_fwd;
+		btf__add_int;
+		btf__add_ptr;
+		btf__add_restrict;
+		btf__add_str;
+		btf__add_struct;
+		btf__add_typedef;
+		btf__add_union;
+		btf__add_var;
+		btf__add_volatile;
+		btf__endianness;
+		btf__find_str;
+		btf__new_empty;
+		btf__set_endianness;
+		btf__str_by_offset;
+		perf_buffer__buffer_cnt;
+		perf_buffer__buffer_fd;
+		perf_buffer__epoll_fd;
+		perf_buffer__consume_buffer;
+} LIBBPF_0.1.0;
+
+LIBBPF_0.3.0 {
+	global:
+		btf__base_btf;
+		btf__parse_elf_split;
+		btf__parse_raw_split;
+		btf__parse_split;
+		btf__new_empty_split;
+		btf__new_split;
+		ring_buffer__epoll_fd;
+} LIBBPF_0.2.0;
+
+LIBBPF_0.4.0 {
+	global:
+		btf__add_float;
+		btf__add_type;
+		bpf_linker__add_file;
+		bpf_linker__finalize;
+		bpf_linker__free;
+		bpf_linker__new;
+		bpf_map__inner_map;
+		bpf_object__set_kversion;
+		bpf_tc_attach;
+		bpf_tc_detach;
+		bpf_tc_hook_create;
+		bpf_tc_hook_destroy;
+		bpf_tc_query;
+} LIBBPF_0.3.0;
+
+LIBBPF_0.5.0 {
+	global:
+		bpf_map__initial_value;
+		bpf_map__pin_path;
+		bpf_map_lookup_and_delete_elem_flags;
+		bpf_program__attach_kprobe_opts;
+		bpf_program__attach_perf_event_opts;
+		bpf_program__attach_tracepoint_opts;
+		bpf_program__attach_uprobe_opts;
+		bpf_object__gen_loader;
+		btf__load_from_kernel_by_id;
+		btf__load_from_kernel_by_id_split;
+		btf__load_into_kernel;
+		btf__load_module_btf;
+		btf__load_vmlinux_btf;
+		btf_dump__dump_type_data;
+		libbpf_set_strict_mode;
+} LIBBPF_0.4.0;
+
+LIBBPF_0.6.0 {
+	global:
+		bpf_map__map_extra;
+		bpf_map__set_map_extra;
+		bpf_map_create;
+		bpf_object__next_map;
+		bpf_object__next_program;
+		bpf_object__prev_map;
+		bpf_object__prev_program;
+		bpf_prog_load;
+		bpf_program__flags;
+		bpf_program__insn_cnt;
+		bpf_program__insns;
+		bpf_program__set_flags;
+		btf__add_btf;
+		btf__add_decl_tag;
+		btf__add_type_tag;
+		btf__dedup;
+		btf__raw_data;
+		btf__type_cnt;
+		btf_dump__new;
+		libbpf_major_version;
+		libbpf_minor_version;
+		libbpf_version_string;
+		perf_buffer__new;
+		perf_buffer__new_raw;
+} LIBBPF_0.5.0;
+
+LIBBPF_0.7.0 {
+	global:
+		bpf_btf_load;
+		bpf_program__expected_attach_type;
+		bpf_program__log_buf;
+		bpf_program__log_level;
+		bpf_program__set_log_buf;
+		bpf_program__set_log_level;
+		bpf_program__type;
+		bpf_xdp_attach;
+		bpf_xdp_detach;
+		bpf_xdp_query;
+		bpf_xdp_query_id;
+		btf_ext__raw_data;
+		libbpf_probe_bpf_helper;
+		libbpf_probe_bpf_map_type;
+		libbpf_probe_bpf_prog_type;
+		libbpf_set_memlock_rlim;
+} LIBBPF_0.6.0;
+
+LIBBPF_0.8.0 {
+	global:
+		bpf_map__autocreate;
+		bpf_map__get_next_key;
+		bpf_map__delete_elem;
+		bpf_map__lookup_and_delete_elem;
+		bpf_map__lookup_elem;
+		bpf_map__set_autocreate;
+		bpf_map__update_elem;
+		bpf_map_delete_elem_flags;
+		bpf_object__destroy_subskeleton;
+		bpf_object__open_subskeleton;
+		bpf_program__attach_kprobe_multi_opts;
+		bpf_program__attach_trace_opts;
+		bpf_program__attach_usdt;
+		bpf_program__set_insns;
+		libbpf_register_prog_handler;
+		libbpf_unregister_prog_handler;
+} LIBBPF_0.7.0;
+
+LIBBPF_1.0.0 {
+	global:
+		bpf_obj_get_opts;
+		bpf_prog_query_opts;
+		bpf_program__attach_ksyscall;
+		bpf_program__autoattach;
+		bpf_program__set_autoattach;
+		btf__add_enum64;
+		btf__add_enum64_value;
+		libbpf_bpf_attach_type_str;
+		libbpf_bpf_link_type_str;
+		libbpf_bpf_map_type_str;
+		libbpf_bpf_prog_type_str;
+		perf_buffer__buffer;
+} LIBBPF_0.8.0;
+
+LIBBPF_1.1.0 {
+	global:
+		bpf_btf_get_fd_by_id_opts;
+		bpf_link_get_fd_by_id_opts;
+		bpf_map_get_fd_by_id_opts;
+		bpf_prog_get_fd_by_id_opts;
+		user_ring_buffer__discard;
+		user_ring_buffer__free;
+		user_ring_buffer__new;
+		user_ring_buffer__reserve;
+		user_ring_buffer__reserve_blocking;
+		user_ring_buffer__submit;
+} LIBBPF_1.0.0;
diff --git a/src/libbpf.pc.template b/src/libbpf.pc.template
new file mode 100644
index 0000000..b45ed53
--- /dev/null
+++ b/src/libbpf.pc.template
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+prefix=@PREFIX@
+libdir=@LIBDIR@
+includedir=${prefix}/include
+
+Name: libbpf
+Description: BPF library
+Version: @VERSION@
+Libs: -L${libdir} -lbpf
+Requires.private: libelf zlib
+Cflags: -I${includedir}
diff --git a/src/libbpf_common.h b/src/libbpf_common.h
new file mode 100644
index 0000000..9a7937f
--- /dev/null
+++ b/src/libbpf_common.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Common user-facing libbpf helpers.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+
+#ifndef __LIBBPF_LIBBPF_COMMON_H
+#define __LIBBPF_LIBBPF_COMMON_H
+
+#include <string.h>
+#include "libbpf_version.h"
+
+#ifndef LIBBPF_API
+#define LIBBPF_API __attribute__((visibility("default")))
+#endif
+
+#define LIBBPF_DEPRECATED(msg) __attribute__((deprecated(msg)))
+
+/* Mark a symbol as deprecated when libbpf version is >= {major}.{minor} */
+#define LIBBPF_DEPRECATED_SINCE(major, minor, msg)			    \
+	__LIBBPF_MARK_DEPRECATED_ ## major ## _ ## minor		    \
+		(LIBBPF_DEPRECATED("libbpf v" # major "." # minor "+: " msg))
+
+#define __LIBBPF_CURRENT_VERSION_GEQ(major, minor)			    \
+	(LIBBPF_MAJOR_VERSION > (major) ||				    \
+	 (LIBBPF_MAJOR_VERSION == (major) && LIBBPF_MINOR_VERSION >= (minor)))
+
+/* Add checks for other versions below when planning deprecation of API symbols
+ * with the LIBBPF_DEPRECATED_SINCE macro.
+ */
+#if __LIBBPF_CURRENT_VERSION_GEQ(1, 0)
+#define __LIBBPF_MARK_DEPRECATED_1_0(X) X
+#else
+#define __LIBBPF_MARK_DEPRECATED_1_0(X)
+#endif
+
+/* This set of internal macros allows to do "function overloading" based on
+ * number of arguments provided by used in backwards-compatible way during the
+ * transition to libbpf 1.0
+ * It's ugly but necessary evil that will be cleaned up when we get to 1.0.
+ * See bpf_prog_load() overload for example.
+ */
+#define ___libbpf_cat(A, B) A ## B
+#define ___libbpf_select(NAME, NUM) ___libbpf_cat(NAME, NUM)
+#define ___libbpf_nth(_1, _2, _3, _4, _5, _6, N, ...) N
+#define ___libbpf_cnt(...) ___libbpf_nth(__VA_ARGS__, 6, 5, 4, 3, 2, 1)
+#define ___libbpf_overload(NAME, ...) ___libbpf_select(NAME, ___libbpf_cnt(__VA_ARGS__))(__VA_ARGS__)
+
+/* Helper macro to declare and initialize libbpf options struct
+ *
+ * This dance with uninitialized declaration, followed by memset to zero,
+ * followed by assignment using compound literal syntax is done to preserve
+ * ability to use a nice struct field initialization syntax and **hopefully**
+ * have all the padding bytes initialized to zero. It's not guaranteed though,
+ * when copying literal, that compiler won't copy garbage in literal's padding
+ * bytes, but that's the best way I've found and it seems to work in practice.
+ *
+ * Macro declares opts struct of given type and name, zero-initializes,
+ * including any extra padding, it with memset() and then assigns initial
+ * values provided by users in struct initializer-syntax as varargs.
+ */
+#define LIBBPF_OPTS(TYPE, NAME, ...)					    \
+	struct TYPE NAME = ({ 						    \
+		memset(&NAME, 0, sizeof(struct TYPE));			    \
+		(struct TYPE) {						    \
+			.sz = sizeof(struct TYPE),			    \
+			__VA_ARGS__					    \
+		};							    \
+	})
+
+#endif /* __LIBBPF_LIBBPF_COMMON_H */
diff --git a/src/libbpf_errno.c b/src/libbpf_errno.c
new file mode 100644
index 0000000..6b18017
--- /dev/null
+++ b/src/libbpf_errno.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ * Copyright (C) 2017 Nicira, Inc.
+ */
+
+#undef _GNU_SOURCE
+#include <stdio.h>
+#include <string.h>
+
+#include "libbpf.h"
+#include "libbpf_internal.h"
+
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
+#define ERRNO_OFFSET(e)		((e) - __LIBBPF_ERRNO__START)
+#define ERRCODE_OFFSET(c)	ERRNO_OFFSET(LIBBPF_ERRNO__##c)
+#define NR_ERRNO	(__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START)
+
+static const char *libbpf_strerror_table[NR_ERRNO] = {
+	[ERRCODE_OFFSET(LIBELF)]	= "Something wrong in libelf",
+	[ERRCODE_OFFSET(FORMAT)]	= "BPF object format invalid",
+	[ERRCODE_OFFSET(KVERSION)]	= "'version' section incorrect or lost",
+	[ERRCODE_OFFSET(ENDIAN)]	= "Endian mismatch",
+	[ERRCODE_OFFSET(INTERNAL)]	= "Internal error in libbpf",
+	[ERRCODE_OFFSET(RELOC)]		= "Relocation failed",
+	[ERRCODE_OFFSET(VERIFY)]	= "Kernel verifier blocks program loading",
+	[ERRCODE_OFFSET(PROG2BIG)]	= "Program too big",
+	[ERRCODE_OFFSET(KVER)]		= "Incorrect kernel version",
+	[ERRCODE_OFFSET(PROGTYPE)]	= "Kernel doesn't support this program type",
+	[ERRCODE_OFFSET(WRNGPID)]	= "Wrong pid in netlink message",
+	[ERRCODE_OFFSET(INVSEQ)]	= "Invalid netlink sequence",
+	[ERRCODE_OFFSET(NLPARSE)]	= "Incorrect netlink message parsing",
+};
+
+int libbpf_strerror(int err, char *buf, size_t size)
+{
+	int ret;
+
+	if (!buf || !size)
+		return libbpf_err(-EINVAL);
+
+	err = err > 0 ? err : -err;
+
+	if (err < __LIBBPF_ERRNO__START) {
+		ret = strerror_r(err, buf, size);
+		buf[size - 1] = '\0';
+		return libbpf_err_errno(ret);
+	}
+
+	if (err < __LIBBPF_ERRNO__END) {
+		const char *msg;
+
+		msg = libbpf_strerror_table[ERRNO_OFFSET(err)];
+		ret = snprintf(buf, size, "%s", msg);
+		buf[size - 1] = '\0';
+		/* The length of the buf and msg is positive.
+		 * A negative number may be returned only when the
+		 * size exceeds INT_MAX. Not likely to appear.
+		 */
+		if (ret >= size)
+			return libbpf_err(-ERANGE);
+		return 0;
+	}
+
+	ret = snprintf(buf, size, "Unknown libbpf error %d", err);
+	buf[size - 1] = '\0';
+	if (ret >= size)
+		return libbpf_err(-ERANGE);
+	return libbpf_err(-ENOENT);
+}
diff --git a/src/libbpf_internal.h b/src/libbpf_internal.h
new file mode 100644
index 0000000..377642f
--- /dev/null
+++ b/src/libbpf_internal.h
@@ -0,0 +1,579 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Internal libbpf helpers.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+
+#ifndef __LIBBPF_LIBBPF_INTERNAL_H
+#define __LIBBPF_LIBBPF_INTERNAL_H
+
+#include <stdlib.h>
+#include <limits.h>
+#include <errno.h>
+#include <linux/err.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include "relo_core.h"
+
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
+/* prevent accidental re-addition of reallocarray() */
+#pragma GCC poison reallocarray
+
+#include "libbpf.h"
+#include "btf.h"
+
+#ifndef EM_BPF
+#define EM_BPF 247
+#endif
+
+#ifndef R_BPF_64_64
+#define R_BPF_64_64 1
+#endif
+#ifndef R_BPF_64_ABS64
+#define R_BPF_64_ABS64 2
+#endif
+#ifndef R_BPF_64_ABS32
+#define R_BPF_64_ABS32 3
+#endif
+#ifndef R_BPF_64_32
+#define R_BPF_64_32 10
+#endif
+
+#ifndef SHT_LLVM_ADDRSIG
+#define SHT_LLVM_ADDRSIG 0x6FFF4C03
+#endif
+
+/* if libelf is old and doesn't support mmap(), fall back to read() */
+#ifndef ELF_C_READ_MMAP
+#define ELF_C_READ_MMAP ELF_C_READ
+#endif
+
+/* Older libelf all end up in this expression, for both 32 and 64 bit */
+#ifndef ELF64_ST_VISIBILITY
+#define ELF64_ST_VISIBILITY(o) ((o) & 0x03)
+#endif
+
+#define BTF_INFO_ENC(kind, kind_flag, vlen) \
+	((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
+#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
+#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
+	((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
+#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
+	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
+	BTF_INT_ENC(encoding, bits_offset, bits)
+#define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
+#define BTF_PARAM_ENC(name, type) (name), (type)
+#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
+#define BTF_TYPE_FLOAT_ENC(name, sz) \
+	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_FLOAT, 0, 0), sz)
+#define BTF_TYPE_DECL_TAG_ENC(value, type, component_idx) \
+	BTF_TYPE_ENC(value, BTF_INFO_ENC(BTF_KIND_DECL_TAG, 0, 0), type), (component_idx)
+#define BTF_TYPE_TYPE_TAG_ENC(value, type) \
+	BTF_TYPE_ENC(value, BTF_INFO_ENC(BTF_KIND_TYPE_TAG, 0, 0), type)
+
+#ifndef likely
+#define likely(x) __builtin_expect(!!(x), 1)
+#endif
+#ifndef unlikely
+#define unlikely(x) __builtin_expect(!!(x), 0)
+#endif
+#ifndef min
+# define min(x, y) ((x) < (y) ? (x) : (y))
+#endif
+#ifndef max
+# define max(x, y) ((x) < (y) ? (y) : (x))
+#endif
+#ifndef offsetofend
+# define offsetofend(TYPE, FIELD) \
+	(offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
+#endif
+#ifndef __alias
+#define __alias(symbol) __attribute__((alias(#symbol)))
+#endif
+
+/* Check whether a string `str` has prefix `pfx`, regardless if `pfx` is
+ * a string literal known at compilation time or char * pointer known only at
+ * runtime.
+ */
+#define str_has_pfx(str, pfx) \
+	(strncmp(str, pfx, __builtin_constant_p(pfx) ? sizeof(pfx) - 1 : strlen(pfx)) == 0)
+
+/* suffix check */
+static inline bool str_has_sfx(const char *str, const char *sfx)
+{
+	size_t str_len = strlen(str);
+	size_t sfx_len = strlen(sfx);
+
+	if (sfx_len > str_len)
+		return false;
+	return strcmp(str + str_len - sfx_len, sfx) == 0;
+}
+
+/* Symbol versioning is different between static and shared library.
+ * Properly versioned symbols are needed for shared library, but
+ * only the symbol of the new version is needed for static library.
+ * Starting with GNU C 10, use symver attribute instead of .symver assembler
+ * directive, which works better with GCC LTO builds.
+ */
+#if defined(SHARED) && defined(__GNUC__) && __GNUC__ >= 10
+
+#define DEFAULT_VERSION(internal_name, api_name, version) \
+	__attribute__((symver(#api_name "@@" #version)))
+#define COMPAT_VERSION(internal_name, api_name, version) \
+	__attribute__((symver(#api_name "@" #version)))
+
+#elif defined(SHARED)
+
+#define COMPAT_VERSION(internal_name, api_name, version) \
+	asm(".symver " #internal_name "," #api_name "@" #version);
+#define DEFAULT_VERSION(internal_name, api_name, version) \
+	asm(".symver " #internal_name "," #api_name "@@" #version);
+
+#else /* !SHARED */
+
+#define COMPAT_VERSION(internal_name, api_name, version)
+#define DEFAULT_VERSION(internal_name, api_name, version) \
+	extern typeof(internal_name) api_name \
+	__attribute__((alias(#internal_name)));
+
+#endif
+
+extern void libbpf_print(enum libbpf_print_level level,
+			 const char *format, ...)
+	__attribute__((format(printf, 2, 3)));
+
+#define __pr(level, fmt, ...)	\
+do {				\
+	libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__);	\
+} while (0)
+
+#define pr_warn(fmt, ...)	__pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
+#define pr_info(fmt, ...)	__pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
+#define pr_debug(fmt, ...)	__pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
+
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+struct bpf_link {
+	int (*detach)(struct bpf_link *link);
+	void (*dealloc)(struct bpf_link *link);
+	char *pin_path;		/* NULL, if not pinned */
+	int fd;			/* hook FD, -1 if not applicable */
+	bool disconnected;
+};
+
+/*
+ * Re-implement glibc's reallocarray() for libbpf internal-only use.
+ * reallocarray(), unfortunately, is not available in all versions of glibc,
+ * so requires extra feature detection and using reallocarray() stub from
+ * <tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates
+ * build of libbpf unnecessarily and is just a maintenance burden. Instead,
+ * it's trivial to implement libbpf-specific internal version and use it
+ * throughout libbpf.
+ */
+static inline void *libbpf_reallocarray(void *ptr, size_t nmemb, size_t size)
+{
+	size_t total;
+
+#if __has_builtin(__builtin_mul_overflow)
+	if (unlikely(__builtin_mul_overflow(nmemb, size, &total)))
+		return NULL;
+#else
+	if (size == 0 || nmemb > ULONG_MAX / size)
+		return NULL;
+	total = nmemb * size;
+#endif
+	return realloc(ptr, total);
+}
+
+/* Copy up to sz - 1 bytes from zero-terminated src string and ensure that dst
+ * is zero-terminated string no matter what (unless sz == 0, in which case
+ * it's a no-op). It's conceptually close to FreeBSD's strlcpy(), but differs
+ * in what is returned. Given this is internal helper, it's trivial to extend
+ * this, when necessary. Use this instead of strncpy inside libbpf source code.
+ */
+static inline void libbpf_strlcpy(char *dst, const char *src, size_t sz)
+{
+	size_t i;
+
+	if (sz == 0)
+		return;
+
+	sz--;
+	for (i = 0; i < sz && src[i]; i++)
+		dst[i] = src[i];
+	dst[i] = '\0';
+}
+
+__u32 get_kernel_version(void);
+
+struct btf;
+struct btf_type;
+
+struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id);
+const char *btf_kind_str(const struct btf_type *t);
+const struct btf_type *skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
+
+static inline enum btf_func_linkage btf_func_linkage(const struct btf_type *t)
+{
+	return (enum btf_func_linkage)(int)btf_vlen(t);
+}
+
+static inline __u32 btf_type_info(int kind, int vlen, int kflag)
+{
+	return (kflag << 31) | (kind << 24) | vlen;
+}
+
+enum map_def_parts {
+	MAP_DEF_MAP_TYPE	= 0x001,
+	MAP_DEF_KEY_TYPE	= 0x002,
+	MAP_DEF_KEY_SIZE	= 0x004,
+	MAP_DEF_VALUE_TYPE	= 0x008,
+	MAP_DEF_VALUE_SIZE	= 0x010,
+	MAP_DEF_MAX_ENTRIES	= 0x020,
+	MAP_DEF_MAP_FLAGS	= 0x040,
+	MAP_DEF_NUMA_NODE	= 0x080,
+	MAP_DEF_PINNING		= 0x100,
+	MAP_DEF_INNER_MAP	= 0x200,
+	MAP_DEF_MAP_EXTRA	= 0x400,
+
+	MAP_DEF_ALL		= 0x7ff, /* combination of all above */
+};
+
+struct btf_map_def {
+	enum map_def_parts parts;
+	__u32 map_type;
+	__u32 key_type_id;
+	__u32 key_size;
+	__u32 value_type_id;
+	__u32 value_size;
+	__u32 max_entries;
+	__u32 map_flags;
+	__u32 numa_node;
+	__u32 pinning;
+	__u64 map_extra;
+};
+
+int parse_btf_map_def(const char *map_name, struct btf *btf,
+		      const struct btf_type *def_t, bool strict,
+		      struct btf_map_def *map_def, struct btf_map_def *inner_def);
+
+void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
+		     size_t cur_cnt, size_t max_cnt, size_t add_cnt);
+int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt);
+
+static inline bool libbpf_is_mem_zeroed(const char *p, ssize_t len)
+{
+	while (len > 0) {
+		if (*p)
+			return false;
+		p++;
+		len--;
+	}
+	return true;
+}
+
+static inline bool libbpf_validate_opts(const char *opts,
+					size_t opts_sz, size_t user_sz,
+					const char *type_name)
+{
+	if (user_sz < sizeof(size_t)) {
+		pr_warn("%s size (%zu) is too small\n", type_name, user_sz);
+		return false;
+	}
+	if (!libbpf_is_mem_zeroed(opts + opts_sz, (ssize_t)user_sz - opts_sz)) {
+		pr_warn("%s has non-zero extra bytes\n", type_name);
+		return false;
+	}
+	return true;
+}
+
+#define OPTS_VALID(opts, type)						      \
+	(!(opts) || libbpf_validate_opts((const char *)opts,		      \
+					 offsetofend(struct type,	      \
+						     type##__last_field),     \
+					 (opts)->sz, #type))
+#define OPTS_HAS(opts, field) \
+	((opts) && opts->sz >= offsetofend(typeof(*(opts)), field))
+#define OPTS_GET(opts, field, fallback_value) \
+	(OPTS_HAS(opts, field) ? (opts)->field : fallback_value)
+#define OPTS_SET(opts, field, value)		\
+	do {					\
+		if (OPTS_HAS(opts, field))	\
+			(opts)->field = value;	\
+	} while (0)
+
+#define OPTS_ZEROED(opts, last_nonzero_field)				      \
+({									      \
+	ssize_t __off = offsetofend(typeof(*(opts)), last_nonzero_field);     \
+	!(opts) || libbpf_is_mem_zeroed((const void *)opts + __off,	      \
+					(opts)->sz - __off);		      \
+})
+
+enum kern_feature_id {
+	/* v4.14: kernel support for program & map names. */
+	FEAT_PROG_NAME,
+	/* v5.2: kernel support for global data sections. */
+	FEAT_GLOBAL_DATA,
+	/* BTF support */
+	FEAT_BTF,
+	/* BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO support */
+	FEAT_BTF_FUNC,
+	/* BTF_KIND_VAR and BTF_KIND_DATASEC support */
+	FEAT_BTF_DATASEC,
+	/* BTF_FUNC_GLOBAL is supported */
+	FEAT_BTF_GLOBAL_FUNC,
+	/* BPF_F_MMAPABLE is supported for arrays */
+	FEAT_ARRAY_MMAP,
+	/* kernel support for expected_attach_type in BPF_PROG_LOAD */
+	FEAT_EXP_ATTACH_TYPE,
+	/* bpf_probe_read_{kernel,user}[_str] helpers */
+	FEAT_PROBE_READ_KERN,
+	/* BPF_PROG_BIND_MAP is supported */
+	FEAT_PROG_BIND_MAP,
+	/* Kernel support for module BTFs */
+	FEAT_MODULE_BTF,
+	/* BTF_KIND_FLOAT support */
+	FEAT_BTF_FLOAT,
+	/* BPF perf link support */
+	FEAT_PERF_LINK,
+	/* BTF_KIND_DECL_TAG support */
+	FEAT_BTF_DECL_TAG,
+	/* BTF_KIND_TYPE_TAG support */
+	FEAT_BTF_TYPE_TAG,
+	/* memcg-based accounting for BPF maps and progs */
+	FEAT_MEMCG_ACCOUNT,
+	/* BPF cookie (bpf_get_attach_cookie() BPF helper) support */
+	FEAT_BPF_COOKIE,
+	/* BTF_KIND_ENUM64 support and BTF_KIND_ENUM kflag support */
+	FEAT_BTF_ENUM64,
+	/* Kernel uses syscall wrapper (CONFIG_ARCH_HAS_SYSCALL_WRAPPER) */
+	FEAT_SYSCALL_WRAPPER,
+	__FEAT_CNT,
+};
+
+int probe_memcg_account(void);
+bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id);
+int bump_rlimit_memlock(void);
+
+int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz);
+int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
+int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
+			 const char *str_sec, size_t str_len);
+int btf_load_into_kernel(struct btf *btf, char *log_buf, size_t log_sz, __u32 log_level);
+
+struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf);
+void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,
+				const char **prefix, int *kind);
+
+struct btf_ext_info {
+	/*
+	 * info points to the individual info section (e.g. func_info and
+	 * line_info) from the .BTF.ext. It does not include the __u32 rec_size.
+	 */
+	void *info;
+	__u32 rec_size;
+	__u32 len;
+	/* optional (maintained internally by libbpf) mapping between .BTF.ext
+	 * section and corresponding ELF section. This is used to join
+	 * information like CO-RE relocation records with corresponding BPF
+	 * programs defined in ELF sections
+	 */
+	__u32 *sec_idxs;
+	int sec_cnt;
+};
+
+#define for_each_btf_ext_sec(seg, sec)					\
+	for (sec = (seg)->info;						\
+	     (void *)sec < (seg)->info + (seg)->len;			\
+	     sec = (void *)sec + sizeof(struct btf_ext_info_sec) +	\
+		   (seg)->rec_size * sec->num_info)
+
+#define for_each_btf_ext_rec(seg, sec, i, rec)				\
+	for (i = 0, rec = (void *)&(sec)->data;				\
+	     i < (sec)->num_info;					\
+	     i++, rec = (void *)rec + (seg)->rec_size)
+
+/*
+ * The .BTF.ext ELF section layout defined as
+ *   struct btf_ext_header
+ *   func_info subsection
+ *
+ * The func_info subsection layout:
+ *   record size for struct bpf_func_info in the func_info subsection
+ *   struct btf_sec_func_info for section #1
+ *   a list of bpf_func_info records for section #1
+ *     where struct bpf_func_info mimics one in include/uapi/linux/bpf.h
+ *     but may not be identical
+ *   struct btf_sec_func_info for section #2
+ *   a list of bpf_func_info records for section #2
+ *   ......
+ *
+ * Note that the bpf_func_info record size in .BTF.ext may not
+ * be the same as the one defined in include/uapi/linux/bpf.h.
+ * The loader should ensure that record_size meets minimum
+ * requirement and pass the record as is to the kernel. The
+ * kernel will handle the func_info properly based on its contents.
+ */
+struct btf_ext_header {
+	__u16	magic;
+	__u8	version;
+	__u8	flags;
+	__u32	hdr_len;
+
+	/* All offsets are in bytes relative to the end of this header */
+	__u32	func_info_off;
+	__u32	func_info_len;
+	__u32	line_info_off;
+	__u32	line_info_len;
+
+	/* optional part of .BTF.ext header */
+	__u32	core_relo_off;
+	__u32	core_relo_len;
+};
+
+struct btf_ext {
+	union {
+		struct btf_ext_header *hdr;
+		void *data;
+	};
+	struct btf_ext_info func_info;
+	struct btf_ext_info line_info;
+	struct btf_ext_info core_relo_info;
+	__u32 data_size;
+};
+
+struct btf_ext_info_sec {
+	__u32	sec_name_off;
+	__u32	num_info;
+	/* Followed by num_info * record_size number of bytes */
+	__u8	data[];
+};
+
+/* The minimum bpf_func_info checked by the loader */
+struct bpf_func_info_min {
+	__u32   insn_off;
+	__u32   type_id;
+};
+
+/* The minimum bpf_line_info checked by the loader */
+struct bpf_line_info_min {
+	__u32	insn_off;
+	__u32	file_name_off;
+	__u32	line_off;
+	__u32	line_col;
+};
+
+
+typedef int (*type_id_visit_fn)(__u32 *type_id, void *ctx);
+typedef int (*str_off_visit_fn)(__u32 *str_off, void *ctx);
+int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx);
+int btf_type_visit_str_offs(struct btf_type *t, str_off_visit_fn visit, void *ctx);
+int btf_ext_visit_type_ids(struct btf_ext *btf_ext, type_id_visit_fn visit, void *ctx);
+int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void *ctx);
+__s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name,
+				 __u32 kind);
+
+typedef int (*kallsyms_cb_t)(unsigned long long sym_addr, char sym_type,
+			     const char *sym_name, void *ctx);
+
+int libbpf_kallsyms_parse(kallsyms_cb_t cb, void *arg);
+
+/* handle direct returned errors */
+static inline int libbpf_err(int ret)
+{
+	if (ret < 0)
+		errno = -ret;
+	return ret;
+}
+
+/* handle errno-based (e.g., syscall or libc) errors according to libbpf's
+ * strict mode settings
+ */
+static inline int libbpf_err_errno(int ret)
+{
+	/* errno is already assumed to be set on error */
+	return ret < 0 ? -errno : ret;
+}
+
+/* handle error for pointer-returning APIs, err is assumed to be < 0 always */
+static inline void *libbpf_err_ptr(int err)
+{
+	/* set errno on error, this doesn't break anything */
+	errno = -err;
+	return NULL;
+}
+
+/* handle pointer-returning APIs' error handling */
+static inline void *libbpf_ptr(void *ret)
+{
+	/* set errno on error, this doesn't break anything */
+	if (IS_ERR(ret))
+		errno = -PTR_ERR(ret);
+
+	return IS_ERR(ret) ? NULL : ret;
+}
+
+static inline bool str_is_empty(const char *s)
+{
+	return !s || !s[0];
+}
+
+static inline bool is_ldimm64_insn(struct bpf_insn *insn)
+{
+	return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
+}
+
+/* if fd is stdin, stdout, or stderr, dup to a fd greater than 2
+ * Takes ownership of the fd passed in, and closes it if calling
+ * fcntl(fd, F_DUPFD_CLOEXEC, 3).
+ */
+static inline int ensure_good_fd(int fd)
+{
+	int old_fd = fd, saved_errno;
+
+	if (fd < 0)
+		return fd;
+	if (fd < 3) {
+		fd = fcntl(fd, F_DUPFD_CLOEXEC, 3);
+		saved_errno = errno;
+		close(old_fd);
+		if (fd < 0) {
+			pr_warn("failed to dup FD %d to FD > 2: %d\n", old_fd, -saved_errno);
+			errno = saved_errno;
+		}
+	}
+	return fd;
+}
+
+/* The following two functions are exposed to bpftool */
+int bpf_core_add_cands(struct bpf_core_cand *local_cand,
+		       size_t local_essent_len,
+		       const struct btf *targ_btf,
+		       const char *targ_btf_name,
+		       int targ_start_id,
+		       struct bpf_core_cand_list *cands);
+void bpf_core_free_cands(struct bpf_core_cand_list *cands);
+
+struct usdt_manager *usdt_manager_new(struct bpf_object *obj);
+void usdt_manager_free(struct usdt_manager *man);
+struct bpf_link * usdt_manager_attach_usdt(struct usdt_manager *man,
+					   const struct bpf_program *prog,
+					   pid_t pid, const char *path,
+					   const char *usdt_provider, const char *usdt_name,
+					   __u64 usdt_cookie);
+
+static inline bool is_pow_of_2(size_t x)
+{
+	return x && (x & (x - 1)) == 0;
+}
+
+#define PROG_LOAD_ATTEMPTS 5
+int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts);
+
+#endif /* __LIBBPF_LIBBPF_INTERNAL_H */
diff --git a/src/libbpf_legacy.h b/src/libbpf_legacy.h
new file mode 100644
index 0000000..1e1be46
--- /dev/null
+++ b/src/libbpf_legacy.h
@@ -0,0 +1,140 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Libbpf legacy APIs (either discouraged or deprecated, as mentioned in [0])
+ *
+ *   [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY
+ *
+ * Copyright (C) 2021 Facebook
+ */
+#ifndef __LIBBPF_LEGACY_BPF_H
+#define __LIBBPF_LEGACY_BPF_H
+
+#include <linux/bpf.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include "libbpf_common.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* As of libbpf 1.0 libbpf_set_strict_mode() and enum libbpf_struct_mode have
+ * no effect. But they are left in libbpf_legacy.h so that applications that
+ * prepared for libbpf 1.0 before final release by using
+ * libbpf_set_strict_mode() still work with libbpf 1.0+ without any changes.
+ */
+enum libbpf_strict_mode {
+	/* Turn on all supported strict features of libbpf to simulate libbpf
+	 * v1.0 behavior.
+	 * This will be the default behavior in libbpf v1.0.
+	 */
+	LIBBPF_STRICT_ALL = 0xffffffff,
+
+	/*
+	 * Disable any libbpf 1.0 behaviors. This is the default before libbpf
+	 * v1.0. It won't be supported anymore in v1.0, please update your
+	 * code so that it handles LIBBPF_STRICT_ALL mode before libbpf v1.0.
+	 */
+	LIBBPF_STRICT_NONE = 0x00,
+	/*
+	 * Return NULL pointers on error, not ERR_PTR(err).
+	 * Additionally, libbpf also always sets errno to corresponding Exx
+	 * (positive) error code.
+	 */
+	LIBBPF_STRICT_CLEAN_PTRS = 0x01,
+	/*
+	 * Return actual error codes from low-level APIs directly, not just -1.
+	 * Additionally, libbpf also always sets errno to corresponding Exx
+	 * (positive) error code.
+	 */
+	LIBBPF_STRICT_DIRECT_ERRS = 0x02,
+	/*
+	 * Enforce strict BPF program section (SEC()) names.
+	 * E.g., while prefiously SEC("xdp_whatever") or SEC("perf_event_blah") were
+	 * allowed, with LIBBPF_STRICT_SEC_PREFIX this will become
+	 * unrecognized by libbpf and would have to be just SEC("xdp") and
+	 * SEC("xdp") and SEC("perf_event").
+	 *
+	 * Note, in this mode the program pin path will be based on the
+	 * function name instead of section name.
+	 *
+	 * Additionally, routines in the .text section are always considered
+	 * sub-programs. Legacy behavior allows for a single routine in .text
+	 * to be a program.
+	 */
+	LIBBPF_STRICT_SEC_NAME = 0x04,
+	/*
+	 * Disable the global 'bpf_objects_list'. Maintaining this list adds
+	 * a race condition to bpf_object__open() and bpf_object__close().
+	 * Clients can maintain it on their own if it is valuable for them.
+	 */
+	LIBBPF_STRICT_NO_OBJECT_LIST = 0x08,
+	/*
+	 * Automatically bump RLIMIT_MEMLOCK using setrlimit() before the
+	 * first BPF program or map creation operation. This is done only if
+	 * kernel is too old to support memcg-based memory accounting for BPF
+	 * subsystem. By default, RLIMIT_MEMLOCK limit is set to RLIM_INFINITY,
+	 * but it can be overriden with libbpf_set_memlock_rlim() API.
+	 * Note that libbpf_set_memlock_rlim() needs to be called before
+	 * the very first bpf_prog_load(), bpf_map_create() or bpf_object__load()
+	 * operation.
+	 */
+	LIBBPF_STRICT_AUTO_RLIMIT_MEMLOCK = 0x10,
+	/*
+	 * Error out on any SEC("maps") map definition, which are deprecated
+	 * in favor of BTF-defined map definitions in SEC(".maps").
+	 */
+	LIBBPF_STRICT_MAP_DEFINITIONS = 0x20,
+
+	__LIBBPF_STRICT_LAST,
+};
+
+LIBBPF_API int libbpf_set_strict_mode(enum libbpf_strict_mode mode);
+
+/**
+ * @brief **libbpf_get_error()** extracts the error code from the passed
+ * pointer
+ * @param ptr pointer returned from libbpf API function
+ * @return error code; or 0 if no error occured
+ *
+ * Note, as of libbpf 1.0 this function is not necessary and not recommended
+ * to be used. Libbpf doesn't return error code embedded into the pointer
+ * itself. Instead, NULL is returned on error and error code is passed through
+ * thread-local errno variable. **libbpf_get_error()** is just returning -errno
+ * value if it receives NULL, which is correct only if errno hasn't been
+ * modified between libbpf API call and corresponding **libbpf_get_error()**
+ * call. Prefer to check return for NULL and use errno directly.
+ *
+ * This API is left in libbpf 1.0 to allow applications that were 1.0-ready
+ * before final libbpf 1.0 without needing to change them.
+ */
+LIBBPF_API long libbpf_get_error(const void *ptr);
+
+#define DECLARE_LIBBPF_OPTS LIBBPF_OPTS
+
+/* "Discouraged" APIs which don't follow consistent libbpf naming patterns.
+ * They are normally a trivial aliases or wrappers for proper APIs and are
+ * left to minimize unnecessary disruption for users of libbpf. But they
+ * shouldn't be used going forward.
+ */
+
+struct bpf_program;
+struct bpf_map;
+struct btf;
+struct btf_ext;
+
+LIBBPF_API struct btf *libbpf_find_kernel_btf(void);
+
+LIBBPF_API enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog);
+LIBBPF_API enum bpf_attach_type bpf_program__get_expected_attach_type(const struct bpf_program *prog);
+LIBBPF_API const char *bpf_map__get_pin_path(const struct bpf_map *map);
+LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
+LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* __LIBBPF_LEGACY_BPF_H */
diff --git a/src/libbpf_probes.c b/src/libbpf_probes.c
new file mode 100644
index 0000000..b44fcbb
--- /dev/null
+++ b/src/libbpf_probes.c
@@ -0,0 +1,364 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2019 Netronome Systems, Inc. */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <net/if.h>
+#include <sys/utsname.h>
+
+#include <linux/btf.h>
+#include <linux/filter.h>
+#include <linux/kernel.h>
+
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+
+static int probe_prog_load(enum bpf_prog_type prog_type,
+			   const struct bpf_insn *insns, size_t insns_cnt,
+			   char *log_buf, size_t log_buf_sz)
+{
+	LIBBPF_OPTS(bpf_prog_load_opts, opts,
+		.log_buf = log_buf,
+		.log_size = log_buf_sz,
+		.log_level = log_buf ? 1 : 0,
+	);
+	int fd, err, exp_err = 0;
+	const char *exp_msg = NULL;
+	char buf[4096];
+
+	switch (prog_type) {
+	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
+		opts.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
+		break;
+	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
+		opts.expected_attach_type = BPF_CGROUP_GETSOCKOPT;
+		break;
+	case BPF_PROG_TYPE_SK_LOOKUP:
+		opts.expected_attach_type = BPF_SK_LOOKUP;
+		break;
+	case BPF_PROG_TYPE_KPROBE:
+		opts.kern_version = get_kernel_version();
+		break;
+	case BPF_PROG_TYPE_LIRC_MODE2:
+		opts.expected_attach_type = BPF_LIRC_MODE2;
+		break;
+	case BPF_PROG_TYPE_TRACING:
+	case BPF_PROG_TYPE_LSM:
+		opts.log_buf = buf;
+		opts.log_size = sizeof(buf);
+		opts.log_level = 1;
+		if (prog_type == BPF_PROG_TYPE_TRACING)
+			opts.expected_attach_type = BPF_TRACE_FENTRY;
+		else
+			opts.expected_attach_type = BPF_MODIFY_RETURN;
+		opts.attach_btf_id = 1;
+
+		exp_err = -EINVAL;
+		exp_msg = "attach_btf_id 1 is not a function";
+		break;
+	case BPF_PROG_TYPE_EXT:
+		opts.log_buf = buf;
+		opts.log_size = sizeof(buf);
+		opts.log_level = 1;
+		opts.attach_btf_id = 1;
+
+		exp_err = -EINVAL;
+		exp_msg = "Cannot replace kernel functions";
+		break;
+	case BPF_PROG_TYPE_SYSCALL:
+		opts.prog_flags = BPF_F_SLEEPABLE;
+		break;
+	case BPF_PROG_TYPE_STRUCT_OPS:
+		exp_err = -524; /* -ENOTSUPP */
+		break;
+	case BPF_PROG_TYPE_UNSPEC:
+	case BPF_PROG_TYPE_SOCKET_FILTER:
+	case BPF_PROG_TYPE_SCHED_CLS:
+	case BPF_PROG_TYPE_SCHED_ACT:
+	case BPF_PROG_TYPE_TRACEPOINT:
+	case BPF_PROG_TYPE_XDP:
+	case BPF_PROG_TYPE_PERF_EVENT:
+	case BPF_PROG_TYPE_CGROUP_SKB:
+	case BPF_PROG_TYPE_CGROUP_SOCK:
+	case BPF_PROG_TYPE_LWT_IN:
+	case BPF_PROG_TYPE_LWT_OUT:
+	case BPF_PROG_TYPE_LWT_XMIT:
+	case BPF_PROG_TYPE_SOCK_OPS:
+	case BPF_PROG_TYPE_SK_SKB:
+	case BPF_PROG_TYPE_CGROUP_DEVICE:
+	case BPF_PROG_TYPE_SK_MSG:
+	case BPF_PROG_TYPE_RAW_TRACEPOINT:
+	case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
+	case BPF_PROG_TYPE_LWT_SEG6LOCAL:
+	case BPF_PROG_TYPE_SK_REUSEPORT:
+	case BPF_PROG_TYPE_FLOW_DISSECTOR:
+	case BPF_PROG_TYPE_CGROUP_SYSCTL:
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts);
+	err = -errno;
+	if (fd >= 0)
+		close(fd);
+	if (exp_err) {
+		if (fd >= 0 || err != exp_err)
+			return 0;
+		if (exp_msg && !strstr(buf, exp_msg))
+			return 0;
+		return 1;
+	}
+	return fd >= 0 ? 1 : 0;
+}
+
+int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts)
+{
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN()
+	};
+	const size_t insn_cnt = ARRAY_SIZE(insns);
+	int ret;
+
+	if (opts)
+		return libbpf_err(-EINVAL);
+
+	ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, 0);
+	return libbpf_err(ret);
+}
+
+int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
+			 const char *str_sec, size_t str_len)
+{
+	struct btf_header hdr = {
+		.magic = BTF_MAGIC,
+		.version = BTF_VERSION,
+		.hdr_len = sizeof(struct btf_header),
+		.type_len = types_len,
+		.str_off = types_len,
+		.str_len = str_len,
+	};
+	int btf_fd, btf_len;
+	__u8 *raw_btf;
+
+	btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len;
+	raw_btf = malloc(btf_len);
+	if (!raw_btf)
+		return -ENOMEM;
+
+	memcpy(raw_btf, &hdr, sizeof(hdr));
+	memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
+	memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);
+
+	btf_fd = bpf_btf_load(raw_btf, btf_len, NULL);
+
+	free(raw_btf);
+	return btf_fd;
+}
+
+static int load_local_storage_btf(void)
+{
+	const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
+	/* struct bpf_spin_lock {
+	 *   int val;
+	 * };
+	 * struct val {
+	 *   int cnt;
+	 *   struct bpf_spin_lock l;
+	 * };
+	 */
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* struct bpf_spin_lock */                      /* [2] */
+		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
+		BTF_MEMBER_ENC(15, 1, 0), /* int val; */
+		/* struct val */                                /* [3] */
+		BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
+		BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
+		BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
+	};
+
+	return libbpf__load_raw_btf((char *)types, sizeof(types),
+				     strs, sizeof(strs));
+}
+
+static int probe_map_create(enum bpf_map_type map_type)
+{
+	LIBBPF_OPTS(bpf_map_create_opts, opts);
+	int key_size, value_size, max_entries;
+	__u32 btf_key_type_id = 0, btf_value_type_id = 0;
+	int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err = 0;
+
+	key_size	= sizeof(__u32);
+	value_size	= sizeof(__u32);
+	max_entries	= 1;
+
+	switch (map_type) {
+	case BPF_MAP_TYPE_STACK_TRACE:
+		value_size	= sizeof(__u64);
+		break;
+	case BPF_MAP_TYPE_LPM_TRIE:
+		key_size	= sizeof(__u64);
+		value_size	= sizeof(__u64);
+		opts.map_flags	= BPF_F_NO_PREALLOC;
+		break;
+	case BPF_MAP_TYPE_CGROUP_STORAGE:
+	case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
+		key_size	= sizeof(struct bpf_cgroup_storage_key);
+		value_size	= sizeof(__u64);
+		max_entries	= 0;
+		break;
+	case BPF_MAP_TYPE_QUEUE:
+	case BPF_MAP_TYPE_STACK:
+		key_size	= 0;
+		break;
+	case BPF_MAP_TYPE_SK_STORAGE:
+	case BPF_MAP_TYPE_INODE_STORAGE:
+	case BPF_MAP_TYPE_TASK_STORAGE:
+	case BPF_MAP_TYPE_CGRP_STORAGE:
+		btf_key_type_id = 1;
+		btf_value_type_id = 3;
+		value_size = 8;
+		max_entries = 0;
+		opts.map_flags = BPF_F_NO_PREALLOC;
+		btf_fd = load_local_storage_btf();
+		if (btf_fd < 0)
+			return btf_fd;
+		break;
+	case BPF_MAP_TYPE_RINGBUF:
+	case BPF_MAP_TYPE_USER_RINGBUF:
+		key_size = 0;
+		value_size = 0;
+		max_entries = sysconf(_SC_PAGE_SIZE);
+		break;
+	case BPF_MAP_TYPE_STRUCT_OPS:
+		/* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */
+		opts.btf_vmlinux_value_type_id = 1;
+		exp_err = -524; /* -ENOTSUPP */
+		break;
+	case BPF_MAP_TYPE_BLOOM_FILTER:
+		key_size = 0;
+		max_entries = 1;
+		break;
+	case BPF_MAP_TYPE_HASH:
+	case BPF_MAP_TYPE_ARRAY:
+	case BPF_MAP_TYPE_PROG_ARRAY:
+	case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
+	case BPF_MAP_TYPE_PERCPU_HASH:
+	case BPF_MAP_TYPE_PERCPU_ARRAY:
+	case BPF_MAP_TYPE_CGROUP_ARRAY:
+	case BPF_MAP_TYPE_LRU_HASH:
+	case BPF_MAP_TYPE_LRU_PERCPU_HASH:
+	case BPF_MAP_TYPE_ARRAY_OF_MAPS:
+	case BPF_MAP_TYPE_HASH_OF_MAPS:
+	case BPF_MAP_TYPE_DEVMAP:
+	case BPF_MAP_TYPE_DEVMAP_HASH:
+	case BPF_MAP_TYPE_SOCKMAP:
+	case BPF_MAP_TYPE_CPUMAP:
+	case BPF_MAP_TYPE_XSKMAP:
+	case BPF_MAP_TYPE_SOCKHASH:
+	case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
+		break;
+	case BPF_MAP_TYPE_UNSPEC:
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
+	    map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
+		fd_inner = bpf_map_create(BPF_MAP_TYPE_HASH, NULL,
+					  sizeof(__u32), sizeof(__u32), 1, NULL);
+		if (fd_inner < 0)
+			goto cleanup;
+
+		opts.inner_map_fd = fd_inner;
+	}
+
+	if (btf_fd >= 0) {
+		opts.btf_fd = btf_fd;
+		opts.btf_key_type_id = btf_key_type_id;
+		opts.btf_value_type_id = btf_value_type_id;
+	}
+
+	fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts);
+	err = -errno;
+
+cleanup:
+	if (fd >= 0)
+		close(fd);
+	if (fd_inner >= 0)
+		close(fd_inner);
+	if (btf_fd >= 0)
+		close(btf_fd);
+
+	if (exp_err)
+		return fd < 0 && err == exp_err ? 1 : 0;
+	else
+		return fd >= 0 ? 1 : 0;
+}
+
+int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts)
+{
+	int ret;
+
+	if (opts)
+		return libbpf_err(-EINVAL);
+
+	ret = probe_map_create(map_type);
+	return libbpf_err(ret);
+}
+
+int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id,
+			    const void *opts)
+{
+	struct bpf_insn insns[] = {
+		BPF_EMIT_CALL((__u32)helper_id),
+		BPF_EXIT_INSN(),
+	};
+	const size_t insn_cnt = ARRAY_SIZE(insns);
+	char buf[4096];
+	int ret;
+
+	if (opts)
+		return libbpf_err(-EINVAL);
+
+	/* we can't successfully load all prog types to check for BPF helper
+	 * support, so bail out with -EOPNOTSUPP error
+	 */
+	switch (prog_type) {
+	case BPF_PROG_TYPE_TRACING:
+	case BPF_PROG_TYPE_EXT:
+	case BPF_PROG_TYPE_LSM:
+	case BPF_PROG_TYPE_STRUCT_OPS:
+		return -EOPNOTSUPP;
+	default:
+		break;
+	}
+
+	buf[0] = '\0';
+	ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf));
+	if (ret < 0)
+		return libbpf_err(ret);
+
+	/* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id)
+	 * at all, it will emit something like "invalid func unknown#181".
+	 * If BPF verifier recognizes BPF helper but it's not supported for
+	 * given BPF program type, it will emit "unknown func bpf_sys_bpf#166".
+	 * In both cases, provided combination of BPF program type and BPF
+	 * helper is not supported by the kernel.
+	 * In all other cases, probe_prog_load() above will either succeed (e.g.,
+	 * because BPF helper happens to accept no input arguments or it
+	 * accepts one input argument and initial PTR_TO_CTX is fine for
+	 * that), or we'll get some more specific BPF verifier error about
+	 * some unsatisfied conditions.
+	 */
+	if (ret == 0 && (strstr(buf, "invalid func ") || strstr(buf, "unknown func ")))
+		return 0;
+	return 1; /* assume supported */
+}
diff --git a/src/libbpf_version.h b/src/libbpf_version.h
new file mode 100644
index 0000000..e944f5b
--- /dev/null
+++ b/src/libbpf_version.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/* Copyright (C) 2021 Facebook */
+#ifndef __LIBBPF_VERSION_H
+#define __LIBBPF_VERSION_H
+
+#define LIBBPF_MAJOR_VERSION 1
+#define LIBBPF_MINOR_VERSION 1
+
+#endif /* __LIBBPF_VERSION_H */
diff --git a/src/linker.c b/src/linker.c
new file mode 100644
index 0000000..4ac02c2
--- /dev/null
+++ b/src/linker.c
@@ -0,0 +1,2900 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/*
+ * BPF static linker
+ *
+ * Copyright (c) 2021 Facebook
+ */
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <linux/err.h>
+#include <linux/btf.h>
+#include <elf.h>
+#include <libelf.h>
+#include <fcntl.h>
+#include "libbpf.h"
+#include "btf.h"
+#include "libbpf_internal.h"
+#include "strset.h"
+
+#define BTF_EXTERN_SEC ".extern"
+
+struct src_sec {
+	const char *sec_name;
+	/* positional (not necessarily ELF) index in an array of sections */
+	int id;
+	/* positional (not necessarily ELF) index of a matching section in a final object file */
+	int dst_id;
+	/* section data offset in a matching output section */
+	int dst_off;
+	/* whether section is omitted from the final ELF file */
+	bool skipped;
+	/* whether section is an ephemeral section, not mapped to an ELF section */
+	bool ephemeral;
+
+	/* ELF info */
+	size_t sec_idx;
+	Elf_Scn *scn;
+	Elf64_Shdr *shdr;
+	Elf_Data *data;
+
+	/* corresponding BTF DATASEC type ID */
+	int sec_type_id;
+};
+
+struct src_obj {
+	const char *filename;
+	int fd;
+	Elf *elf;
+	/* Section header strings section index */
+	size_t shstrs_sec_idx;
+	/* SYMTAB section index */
+	size_t symtab_sec_idx;
+
+	struct btf *btf;
+	struct btf_ext *btf_ext;
+
+	/* List of sections (including ephemeral). Slot zero is unused. */
+	struct src_sec *secs;
+	int sec_cnt;
+
+	/* mapping of symbol indices from src to dst ELF */
+	int *sym_map;
+	/* mapping from the src BTF type IDs to dst ones */
+	int *btf_type_map;
+};
+
+/* single .BTF.ext data section */
+struct btf_ext_sec_data {
+	size_t rec_cnt;
+	__u32 rec_sz;
+	void *recs;
+};
+
+struct glob_sym {
+	/* ELF symbol index */
+	int sym_idx;
+	/* associated section id for .ksyms, .kconfig, etc, but not .extern */
+	int sec_id;
+	/* extern name offset in STRTAB */
+	int name_off;
+	/* optional associated BTF type ID */
+	int btf_id;
+	/* BTF type ID to which VAR/FUNC type is pointing to; used for
+	 * rewriting types when extern VAR/FUNC is resolved to a concrete
+	 * definition
+	 */
+	int underlying_btf_id;
+	/* sec_var index in the corresponding dst_sec, if exists */
+	int var_idx;
+
+	/* extern or resolved/global symbol */
+	bool is_extern;
+	/* weak or strong symbol, never goes back from strong to weak */
+	bool is_weak;
+};
+
+struct dst_sec {
+	char *sec_name;
+	/* positional (not necessarily ELF) index in an array of sections */
+	int id;
+
+	bool ephemeral;
+
+	/* ELF info */
+	size_t sec_idx;
+	Elf_Scn *scn;
+	Elf64_Shdr *shdr;
+	Elf_Data *data;
+
+	/* final output section size */
+	int sec_sz;
+	/* final output contents of the section */
+	void *raw_data;
+
+	/* corresponding STT_SECTION symbol index in SYMTAB */
+	int sec_sym_idx;
+
+	/* section's DATASEC variable info, emitted on BTF finalization */
+	bool has_btf;
+	int sec_var_cnt;
+	struct btf_var_secinfo *sec_vars;
+
+	/* section's .BTF.ext data */
+	struct btf_ext_sec_data func_info;
+	struct btf_ext_sec_data line_info;
+	struct btf_ext_sec_data core_relo_info;
+};
+
+struct bpf_linker {
+	char *filename;
+	int fd;
+	Elf *elf;
+	Elf64_Ehdr *elf_hdr;
+
+	/* Output sections metadata */
+	struct dst_sec *secs;
+	int sec_cnt;
+
+	struct strset *strtab_strs; /* STRTAB unique strings */
+	size_t strtab_sec_idx; /* STRTAB section index */
+	size_t symtab_sec_idx; /* SYMTAB section index */
+
+	struct btf *btf;
+	struct btf_ext *btf_ext;
+
+	/* global (including extern) ELF symbols */
+	int glob_sym_cnt;
+	struct glob_sym *glob_syms;
+};
+
+#define pr_warn_elf(fmt, ...)									\
+	libbpf_print(LIBBPF_WARN, "libbpf: " fmt ": %s\n", ##__VA_ARGS__, elf_errmsg(-1))
+
+static int init_output_elf(struct bpf_linker *linker, const char *file);
+
+static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
+				const struct bpf_linker_file_opts *opts,
+				struct src_obj *obj);
+static int linker_sanity_check_elf(struct src_obj *obj);
+static int linker_sanity_check_elf_symtab(struct src_obj *obj, struct src_sec *sec);
+static int linker_sanity_check_elf_relos(struct src_obj *obj, struct src_sec *sec);
+static int linker_sanity_check_btf(struct src_obj *obj);
+static int linker_sanity_check_btf_ext(struct src_obj *obj);
+static int linker_fixup_btf(struct src_obj *obj);
+static int linker_append_sec_data(struct bpf_linker *linker, struct src_obj *obj);
+static int linker_append_elf_syms(struct bpf_linker *linker, struct src_obj *obj);
+static int linker_append_elf_sym(struct bpf_linker *linker, struct src_obj *obj,
+				 Elf64_Sym *sym, const char *sym_name, int src_sym_idx);
+static int linker_append_elf_relos(struct bpf_linker *linker, struct src_obj *obj);
+static int linker_append_btf(struct bpf_linker *linker, struct src_obj *obj);
+static int linker_append_btf_ext(struct bpf_linker *linker, struct src_obj *obj);
+
+static int finalize_btf(struct bpf_linker *linker);
+static int finalize_btf_ext(struct bpf_linker *linker);
+
+void bpf_linker__free(struct bpf_linker *linker)
+{
+	int i;
+
+	if (!linker)
+		return;
+
+	free(linker->filename);
+
+	if (linker->elf)
+		elf_end(linker->elf);
+
+	if (linker->fd >= 0)
+		close(linker->fd);
+
+	strset__free(linker->strtab_strs);
+
+	btf__free(linker->btf);
+	btf_ext__free(linker->btf_ext);
+
+	for (i = 1; i < linker->sec_cnt; i++) {
+		struct dst_sec *sec = &linker->secs[i];
+
+		free(sec->sec_name);
+		free(sec->raw_data);
+		free(sec->sec_vars);
+
+		free(sec->func_info.recs);
+		free(sec->line_info.recs);
+		free(sec->core_relo_info.recs);
+	}
+	free(linker->secs);
+
+	free(linker->glob_syms);
+	free(linker);
+}
+
+struct bpf_linker *bpf_linker__new(const char *filename, struct bpf_linker_opts *opts)
+{
+	struct bpf_linker *linker;
+	int err;
+
+	if (!OPTS_VALID(opts, bpf_linker_opts))
+		return errno = EINVAL, NULL;
+
+	if (elf_version(EV_CURRENT) == EV_NONE) {
+		pr_warn_elf("libelf initialization failed");
+		return errno = EINVAL, NULL;
+	}
+
+	linker = calloc(1, sizeof(*linker));
+	if (!linker)
+		return errno = ENOMEM, NULL;
+
+	linker->fd = -1;
+
+	err = init_output_elf(linker, filename);
+	if (err)
+		goto err_out;
+
+	return linker;
+
+err_out:
+	bpf_linker__free(linker);
+	return errno = -err, NULL;
+}
+
+static struct dst_sec *add_dst_sec(struct bpf_linker *linker, const char *sec_name)
+{
+	struct dst_sec *secs = linker->secs, *sec;
+	size_t new_cnt = linker->sec_cnt ? linker->sec_cnt + 1 : 2;
+
+	secs = libbpf_reallocarray(secs, new_cnt, sizeof(*secs));
+	if (!secs)
+		return NULL;
+
+	/* zero out newly allocated memory */
+	memset(secs + linker->sec_cnt, 0, (new_cnt - linker->sec_cnt) * sizeof(*secs));
+
+	linker->secs = secs;
+	linker->sec_cnt = new_cnt;
+
+	sec = &linker->secs[new_cnt - 1];
+	sec->id = new_cnt - 1;
+	sec->sec_name = strdup(sec_name);
+	if (!sec->sec_name)
+		return NULL;
+
+	return sec;
+}
+
+static Elf64_Sym *add_new_sym(struct bpf_linker *linker, size_t *sym_idx)
+{
+	struct dst_sec *symtab = &linker->secs[linker->symtab_sec_idx];
+	Elf64_Sym *syms, *sym;
+	size_t sym_cnt = symtab->sec_sz / sizeof(*sym);
+
+	syms = libbpf_reallocarray(symtab->raw_data, sym_cnt + 1, sizeof(*sym));
+	if (!syms)
+		return NULL;
+
+	sym = &syms[sym_cnt];
+	memset(sym, 0, sizeof(*sym));
+
+	symtab->raw_data = syms;
+	symtab->sec_sz += sizeof(*sym);
+	symtab->shdr->sh_size += sizeof(*sym);
+	symtab->data->d_size += sizeof(*sym);
+
+	if (sym_idx)
+		*sym_idx = sym_cnt;
+
+	return sym;
+}
+
+static int init_output_elf(struct bpf_linker *linker, const char *file)
+{
+	int err, str_off;
+	Elf64_Sym *init_sym;
+	struct dst_sec *sec;
+
+	linker->filename = strdup(file);
+	if (!linker->filename)
+		return -ENOMEM;
+
+	linker->fd = open(file, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
+	if (linker->fd < 0) {
+		err = -errno;
+		pr_warn("failed to create '%s': %d\n", file, err);
+		return err;
+	}
+
+	linker->elf = elf_begin(linker->fd, ELF_C_WRITE, NULL);
+	if (!linker->elf) {
+		pr_warn_elf("failed to create ELF object");
+		return -EINVAL;
+	}
+
+	/* ELF header */
+	linker->elf_hdr = elf64_newehdr(linker->elf);
+	if (!linker->elf_hdr) {
+		pr_warn_elf("failed to create ELF header");
+		return -EINVAL;
+	}
+
+	linker->elf_hdr->e_machine = EM_BPF;
+	linker->elf_hdr->e_type = ET_REL;
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	linker->elf_hdr->e_ident[EI_DATA] = ELFDATA2LSB;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+	linker->elf_hdr->e_ident[EI_DATA] = ELFDATA2MSB;
+#else
+#error "Unknown __BYTE_ORDER__"
+#endif
+
+	/* STRTAB */
+	/* initialize strset with an empty string to conform to ELF */
+	linker->strtab_strs = strset__new(INT_MAX, "", sizeof(""));
+	if (libbpf_get_error(linker->strtab_strs))
+		return libbpf_get_error(linker->strtab_strs);
+
+	sec = add_dst_sec(linker, ".strtab");
+	if (!sec)
+		return -ENOMEM;
+
+	sec->scn = elf_newscn(linker->elf);
+	if (!sec->scn) {
+		pr_warn_elf("failed to create STRTAB section");
+		return -EINVAL;
+	}
+
+	sec->shdr = elf64_getshdr(sec->scn);
+	if (!sec->shdr)
+		return -EINVAL;
+
+	sec->data = elf_newdata(sec->scn);
+	if (!sec->data) {
+		pr_warn_elf("failed to create STRTAB data");
+		return -EINVAL;
+	}
+
+	str_off = strset__add_str(linker->strtab_strs, sec->sec_name);
+	if (str_off < 0)
+		return str_off;
+
+	sec->sec_idx = elf_ndxscn(sec->scn);
+	linker->elf_hdr->e_shstrndx = sec->sec_idx;
+	linker->strtab_sec_idx = sec->sec_idx;
+
+	sec->shdr->sh_name = str_off;
+	sec->shdr->sh_type = SHT_STRTAB;
+	sec->shdr->sh_flags = SHF_STRINGS;
+	sec->shdr->sh_offset = 0;
+	sec->shdr->sh_link = 0;
+	sec->shdr->sh_info = 0;
+	sec->shdr->sh_addralign = 1;
+	sec->shdr->sh_size = sec->sec_sz = 0;
+	sec->shdr->sh_entsize = 0;
+
+	/* SYMTAB */
+	sec = add_dst_sec(linker, ".symtab");
+	if (!sec)
+		return -ENOMEM;
+
+	sec->scn = elf_newscn(linker->elf);
+	if (!sec->scn) {
+		pr_warn_elf("failed to create SYMTAB section");
+		return -EINVAL;
+	}
+
+	sec->shdr = elf64_getshdr(sec->scn);
+	if (!sec->shdr)
+		return -EINVAL;
+
+	sec->data = elf_newdata(sec->scn);
+	if (!sec->data) {
+		pr_warn_elf("failed to create SYMTAB data");
+		return -EINVAL;
+	}
+
+	str_off = strset__add_str(linker->strtab_strs, sec->sec_name);
+	if (str_off < 0)
+		return str_off;
+
+	sec->sec_idx = elf_ndxscn(sec->scn);
+	linker->symtab_sec_idx = sec->sec_idx;
+
+	sec->shdr->sh_name = str_off;
+	sec->shdr->sh_type = SHT_SYMTAB;
+	sec->shdr->sh_flags = 0;
+	sec->shdr->sh_offset = 0;
+	sec->shdr->sh_link = linker->strtab_sec_idx;
+	/* sh_info should be one greater than the index of the last local
+	 * symbol (i.e., binding is STB_LOCAL). But why and who cares?
+	 */
+	sec->shdr->sh_info = 0;
+	sec->shdr->sh_addralign = 8;
+	sec->shdr->sh_entsize = sizeof(Elf64_Sym);
+
+	/* .BTF */
+	linker->btf = btf__new_empty();
+	err = libbpf_get_error(linker->btf);
+	if (err)
+		return err;
+
+	/* add the special all-zero symbol */
+	init_sym = add_new_sym(linker, NULL);
+	if (!init_sym)
+		return -EINVAL;
+
+	init_sym->st_name = 0;
+	init_sym->st_info = 0;
+	init_sym->st_other = 0;
+	init_sym->st_shndx = SHN_UNDEF;
+	init_sym->st_value = 0;
+	init_sym->st_size = 0;
+
+	return 0;
+}
+
+int bpf_linker__add_file(struct bpf_linker *linker, const char *filename,
+			 const struct bpf_linker_file_opts *opts)
+{
+	struct src_obj obj = {};
+	int err = 0;
+
+	if (!OPTS_VALID(opts, bpf_linker_file_opts))
+		return libbpf_err(-EINVAL);
+
+	if (!linker->elf)
+		return libbpf_err(-EINVAL);
+
+	err = err ?: linker_load_obj_file(linker, filename, opts, &obj);
+	err = err ?: linker_append_sec_data(linker, &obj);
+	err = err ?: linker_append_elf_syms(linker, &obj);
+	err = err ?: linker_append_elf_relos(linker, &obj);
+	err = err ?: linker_append_btf(linker, &obj);
+	err = err ?: linker_append_btf_ext(linker, &obj);
+
+	/* free up src_obj resources */
+	free(obj.btf_type_map);
+	btf__free(obj.btf);
+	btf_ext__free(obj.btf_ext);
+	free(obj.secs);
+	free(obj.sym_map);
+	if (obj.elf)
+		elf_end(obj.elf);
+	if (obj.fd >= 0)
+		close(obj.fd);
+
+	return libbpf_err(err);
+}
+
+static bool is_dwarf_sec_name(const char *name)
+{
+	/* approximation, but the actual list is too long */
+	return strncmp(name, ".debug_", sizeof(".debug_") - 1) == 0;
+}
+
+static bool is_ignored_sec(struct src_sec *sec)
+{
+	Elf64_Shdr *shdr = sec->shdr;
+	const char *name = sec->sec_name;
+
+	/* no special handling of .strtab */
+	if (shdr->sh_type == SHT_STRTAB)
+		return true;
+
+	/* ignore .llvm_addrsig section as well */
+	if (shdr->sh_type == SHT_LLVM_ADDRSIG)
+		return true;
+
+	/* no subprograms will lead to an empty .text section, ignore it */
+	if (shdr->sh_type == SHT_PROGBITS && shdr->sh_size == 0 &&
+	    strcmp(sec->sec_name, ".text") == 0)
+		return true;
+
+	/* DWARF sections */
+	if (is_dwarf_sec_name(sec->sec_name))
+		return true;
+
+	if (strncmp(name, ".rel", sizeof(".rel") - 1) == 0) {
+		name += sizeof(".rel") - 1;
+		/* DWARF section relocations */
+		if (is_dwarf_sec_name(name))
+			return true;
+
+		/* .BTF and .BTF.ext don't need relocations */
+		if (strcmp(name, BTF_ELF_SEC) == 0 ||
+		    strcmp(name, BTF_EXT_ELF_SEC) == 0)
+			return true;
+	}
+
+	return false;
+}
+
+static struct src_sec *add_src_sec(struct src_obj *obj, const char *sec_name)
+{
+	struct src_sec *secs = obj->secs, *sec;
+	size_t new_cnt = obj->sec_cnt ? obj->sec_cnt + 1 : 2;
+
+	secs = libbpf_reallocarray(secs, new_cnt, sizeof(*secs));
+	if (!secs)
+		return NULL;
+
+	/* zero out newly allocated memory */
+	memset(secs + obj->sec_cnt, 0, (new_cnt - obj->sec_cnt) * sizeof(*secs));
+
+	obj->secs = secs;
+	obj->sec_cnt = new_cnt;
+
+	sec = &obj->secs[new_cnt - 1];
+	sec->id = new_cnt - 1;
+	sec->sec_name = sec_name;
+
+	return sec;
+}
+
+static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
+				const struct bpf_linker_file_opts *opts,
+				struct src_obj *obj)
+{
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	const int host_endianness = ELFDATA2LSB;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+	const int host_endianness = ELFDATA2MSB;
+#else
+#error "Unknown __BYTE_ORDER__"
+#endif
+	int err = 0;
+	Elf_Scn *scn;
+	Elf_Data *data;
+	Elf64_Ehdr *ehdr;
+	Elf64_Shdr *shdr;
+	struct src_sec *sec;
+
+	pr_debug("linker: adding object file '%s'...\n", filename);
+
+	obj->filename = filename;
+
+	obj->fd = open(filename, O_RDONLY | O_CLOEXEC);
+	if (obj->fd < 0) {
+		err = -errno;
+		pr_warn("failed to open file '%s': %d\n", filename, err);
+		return err;
+	}
+	obj->elf = elf_begin(obj->fd, ELF_C_READ_MMAP, NULL);
+	if (!obj->elf) {
+		err = -errno;
+		pr_warn_elf("failed to parse ELF file '%s'", filename);
+		return err;
+	}
+
+	/* Sanity check ELF file high-level properties */
+	ehdr = elf64_getehdr(obj->elf);
+	if (!ehdr) {
+		err = -errno;
+		pr_warn_elf("failed to get ELF header for %s", filename);
+		return err;
+	}
+	if (ehdr->e_ident[EI_DATA] != host_endianness) {
+		err = -EOPNOTSUPP;
+		pr_warn_elf("unsupported byte order of ELF file %s", filename);
+		return err;
+	}
+	if (ehdr->e_type != ET_REL
+	    || ehdr->e_machine != EM_BPF
+	    || ehdr->e_ident[EI_CLASS] != ELFCLASS64) {
+		err = -EOPNOTSUPP;
+		pr_warn_elf("unsupported kind of ELF file %s", filename);
+		return err;
+	}
+
+	if (elf_getshdrstrndx(obj->elf, &obj->shstrs_sec_idx)) {
+		err = -errno;
+		pr_warn_elf("failed to get SHSTRTAB section index for %s", filename);
+		return err;
+	}
+
+	scn = NULL;
+	while ((scn = elf_nextscn(obj->elf, scn)) != NULL) {
+		size_t sec_idx = elf_ndxscn(scn);
+		const char *sec_name;
+
+		shdr = elf64_getshdr(scn);
+		if (!shdr) {
+			err = -errno;
+			pr_warn_elf("failed to get section #%zu header for %s",
+				    sec_idx, filename);
+			return err;
+		}
+
+		sec_name = elf_strptr(obj->elf, obj->shstrs_sec_idx, shdr->sh_name);
+		if (!sec_name) {
+			err = -errno;
+			pr_warn_elf("failed to get section #%zu name for %s",
+				    sec_idx, filename);
+			return err;
+		}
+
+		data = elf_getdata(scn, 0);
+		if (!data) {
+			err = -errno;
+			pr_warn_elf("failed to get section #%zu (%s) data from %s",
+				    sec_idx, sec_name, filename);
+			return err;
+		}
+
+		sec = add_src_sec(obj, sec_name);
+		if (!sec)
+			return -ENOMEM;
+
+		sec->scn = scn;
+		sec->shdr = shdr;
+		sec->data = data;
+		sec->sec_idx = elf_ndxscn(scn);
+
+		if (is_ignored_sec(sec)) {
+			sec->skipped = true;
+			continue;
+		}
+
+		switch (shdr->sh_type) {
+		case SHT_SYMTAB:
+			if (obj->symtab_sec_idx) {
+				err = -EOPNOTSUPP;
+				pr_warn("multiple SYMTAB sections found, not supported\n");
+				return err;
+			}
+			obj->symtab_sec_idx = sec_idx;
+			break;
+		case SHT_STRTAB:
+			/* we'll construct our own string table */
+			break;
+		case SHT_PROGBITS:
+			if (strcmp(sec_name, BTF_ELF_SEC) == 0) {
+				obj->btf = btf__new(data->d_buf, shdr->sh_size);
+				err = libbpf_get_error(obj->btf);
+				if (err) {
+					pr_warn("failed to parse .BTF from %s: %d\n", filename, err);
+					return err;
+				}
+				sec->skipped = true;
+				continue;
+			}
+			if (strcmp(sec_name, BTF_EXT_ELF_SEC) == 0) {
+				obj->btf_ext = btf_ext__new(data->d_buf, shdr->sh_size);
+				err = libbpf_get_error(obj->btf_ext);
+				if (err) {
+					pr_warn("failed to parse .BTF.ext from '%s': %d\n", filename, err);
+					return err;
+				}
+				sec->skipped = true;
+				continue;
+			}
+
+			/* data & code */
+			break;
+		case SHT_NOBITS:
+			/* BSS */
+			break;
+		case SHT_REL:
+			/* relocations */
+			break;
+		default:
+			pr_warn("unrecognized section #%zu (%s) in %s\n",
+				sec_idx, sec_name, filename);
+			err = -EINVAL;
+			return err;
+		}
+	}
+
+	err = err ?: linker_sanity_check_elf(obj);
+	err = err ?: linker_sanity_check_btf(obj);
+	err = err ?: linker_sanity_check_btf_ext(obj);
+	err = err ?: linker_fixup_btf(obj);
+
+	return err;
+}
+
+static int linker_sanity_check_elf(struct src_obj *obj)
+{
+	struct src_sec *sec;
+	int i, err;
+
+	if (!obj->symtab_sec_idx) {
+		pr_warn("ELF is missing SYMTAB section in %s\n", obj->filename);
+		return -EINVAL;
+	}
+	if (!obj->shstrs_sec_idx) {
+		pr_warn("ELF is missing section headers STRTAB section in %s\n", obj->filename);
+		return -EINVAL;
+	}
+
+	for (i = 1; i < obj->sec_cnt; i++) {
+		sec = &obj->secs[i];
+
+		if (sec->sec_name[0] == '\0') {
+			pr_warn("ELF section #%zu has empty name in %s\n", sec->sec_idx, obj->filename);
+			return -EINVAL;
+		}
+
+		if (sec->shdr->sh_addralign && !is_pow_of_2(sec->shdr->sh_addralign))
+			return -EINVAL;
+		if (sec->shdr->sh_addralign != sec->data->d_align)
+			return -EINVAL;
+
+		if (sec->shdr->sh_size != sec->data->d_size)
+			return -EINVAL;
+
+		switch (sec->shdr->sh_type) {
+		case SHT_SYMTAB:
+			err = linker_sanity_check_elf_symtab(obj, sec);
+			if (err)
+				return err;
+			break;
+		case SHT_STRTAB:
+			break;
+		case SHT_PROGBITS:
+			if (sec->shdr->sh_flags & SHF_EXECINSTR) {
+				if (sec->shdr->sh_size % sizeof(struct bpf_insn) != 0)
+					return -EINVAL;
+			}
+			break;
+		case SHT_NOBITS:
+			break;
+		case SHT_REL:
+			err = linker_sanity_check_elf_relos(obj, sec);
+			if (err)
+				return err;
+			break;
+		case SHT_LLVM_ADDRSIG:
+			break;
+		default:
+			pr_warn("ELF section #%zu (%s) has unrecognized type %zu in %s\n",
+				sec->sec_idx, sec->sec_name, (size_t)sec->shdr->sh_type, obj->filename);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int linker_sanity_check_elf_symtab(struct src_obj *obj, struct src_sec *sec)
+{
+	struct src_sec *link_sec;
+	Elf64_Sym *sym;
+	int i, n;
+
+	if (sec->shdr->sh_entsize != sizeof(Elf64_Sym))
+		return -EINVAL;
+	if (sec->shdr->sh_size % sec->shdr->sh_entsize != 0)
+		return -EINVAL;
+
+	if (!sec->shdr->sh_link || sec->shdr->sh_link >= obj->sec_cnt) {
+		pr_warn("ELF SYMTAB section #%zu points to missing STRTAB section #%zu in %s\n",
+			sec->sec_idx, (size_t)sec->shdr->sh_link, obj->filename);
+		return -EINVAL;
+	}
+	link_sec = &obj->secs[sec->shdr->sh_link];
+	if (link_sec->shdr->sh_type != SHT_STRTAB) {
+		pr_warn("ELF SYMTAB section #%zu points to invalid STRTAB section #%zu in %s\n",
+			sec->sec_idx, (size_t)sec->shdr->sh_link, obj->filename);
+		return -EINVAL;
+	}
+
+	n = sec->shdr->sh_size / sec->shdr->sh_entsize;
+	sym = sec->data->d_buf;
+	for (i = 0; i < n; i++, sym++) {
+		int sym_type = ELF64_ST_TYPE(sym->st_info);
+		int sym_bind = ELF64_ST_BIND(sym->st_info);
+		int sym_vis = ELF64_ST_VISIBILITY(sym->st_other);
+
+		if (i == 0) {
+			if (sym->st_name != 0 || sym->st_info != 0
+			    || sym->st_other != 0 || sym->st_shndx != 0
+			    || sym->st_value != 0 || sym->st_size != 0) {
+				pr_warn("ELF sym #0 is invalid in %s\n", obj->filename);
+				return -EINVAL;
+			}
+			continue;
+		}
+		if (sym_bind != STB_LOCAL && sym_bind != STB_GLOBAL && sym_bind != STB_WEAK) {
+			pr_warn("ELF sym #%d in section #%zu has unsupported symbol binding %d\n",
+				i, sec->sec_idx, sym_bind);
+			return -EINVAL;
+		}
+		if (sym_vis != STV_DEFAULT && sym_vis != STV_HIDDEN) {
+			pr_warn("ELF sym #%d in section #%zu has unsupported symbol visibility %d\n",
+				i, sec->sec_idx, sym_vis);
+			return -EINVAL;
+		}
+		if (sym->st_shndx == 0) {
+			if (sym_type != STT_NOTYPE || sym_bind == STB_LOCAL
+			    || sym->st_value != 0 || sym->st_size != 0) {
+				pr_warn("ELF sym #%d is invalid extern symbol in %s\n",
+					i, obj->filename);
+
+				return -EINVAL;
+			}
+			continue;
+		}
+		if (sym->st_shndx < SHN_LORESERVE && sym->st_shndx >= obj->sec_cnt) {
+			pr_warn("ELF sym #%d in section #%zu points to missing section #%zu in %s\n",
+				i, sec->sec_idx, (size_t)sym->st_shndx, obj->filename);
+			return -EINVAL;
+		}
+		if (sym_type == STT_SECTION) {
+			if (sym->st_value != 0)
+				return -EINVAL;
+			continue;
+		}
+	}
+
+	return 0;
+}
+
+static int linker_sanity_check_elf_relos(struct src_obj *obj, struct src_sec *sec)
+{
+	struct src_sec *link_sec, *sym_sec;
+	Elf64_Rel *relo;
+	int i, n;
+
+	if (sec->shdr->sh_entsize != sizeof(Elf64_Rel))
+		return -EINVAL;
+	if (sec->shdr->sh_size % sec->shdr->sh_entsize != 0)
+		return -EINVAL;
+
+	/* SHT_REL's sh_link should point to SYMTAB */
+	if (sec->shdr->sh_link != obj->symtab_sec_idx) {
+		pr_warn("ELF relo section #%zu points to invalid SYMTAB section #%zu in %s\n",
+			sec->sec_idx, (size_t)sec->shdr->sh_link, obj->filename);
+		return -EINVAL;
+	}
+
+	/* SHT_REL's sh_info points to relocated section */
+	if (!sec->shdr->sh_info || sec->shdr->sh_info >= obj->sec_cnt) {
+		pr_warn("ELF relo section #%zu points to missing section #%zu in %s\n",
+			sec->sec_idx, (size_t)sec->shdr->sh_info, obj->filename);
+		return -EINVAL;
+	}
+	link_sec = &obj->secs[sec->shdr->sh_info];
+
+	/* .rel<secname> -> <secname> pattern is followed */
+	if (strncmp(sec->sec_name, ".rel", sizeof(".rel") - 1) != 0
+	    || strcmp(sec->sec_name + sizeof(".rel") - 1, link_sec->sec_name) != 0) {
+		pr_warn("ELF relo section #%zu name has invalid name in %s\n",
+			sec->sec_idx, obj->filename);
+		return -EINVAL;
+	}
+
+	/* don't further validate relocations for ignored sections */
+	if (link_sec->skipped)
+		return 0;
+
+	/* relocatable section is data or instructions */
+	if (link_sec->shdr->sh_type != SHT_PROGBITS && link_sec->shdr->sh_type != SHT_NOBITS) {
+		pr_warn("ELF relo section #%zu points to invalid section #%zu in %s\n",
+			sec->sec_idx, (size_t)sec->shdr->sh_info, obj->filename);
+		return -EINVAL;
+	}
+
+	/* check sanity of each relocation */
+	n = sec->shdr->sh_size / sec->shdr->sh_entsize;
+	relo = sec->data->d_buf;
+	sym_sec = &obj->secs[obj->symtab_sec_idx];
+	for (i = 0; i < n; i++, relo++) {
+		size_t sym_idx = ELF64_R_SYM(relo->r_info);
+		size_t sym_type = ELF64_R_TYPE(relo->r_info);
+
+		if (sym_type != R_BPF_64_64 && sym_type != R_BPF_64_32 &&
+		    sym_type != R_BPF_64_ABS64 && sym_type != R_BPF_64_ABS32) {
+			pr_warn("ELF relo #%d in section #%zu has unexpected type %zu in %s\n",
+				i, sec->sec_idx, sym_type, obj->filename);
+			return -EINVAL;
+		}
+
+		if (!sym_idx || sym_idx * sizeof(Elf64_Sym) >= sym_sec->shdr->sh_size) {
+			pr_warn("ELF relo #%d in section #%zu points to invalid symbol #%zu in %s\n",
+				i, sec->sec_idx, sym_idx, obj->filename);
+			return -EINVAL;
+		}
+
+		if (link_sec->shdr->sh_flags & SHF_EXECINSTR) {
+			if (relo->r_offset % sizeof(struct bpf_insn) != 0) {
+				pr_warn("ELF relo #%d in section #%zu points to missing symbol #%zu in %s\n",
+					i, sec->sec_idx, sym_idx, obj->filename);
+				return -EINVAL;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static int check_btf_type_id(__u32 *type_id, void *ctx)
+{
+	struct btf *btf = ctx;
+
+	if (*type_id >= btf__type_cnt(btf))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int check_btf_str_off(__u32 *str_off, void *ctx)
+{
+	struct btf *btf = ctx;
+	const char *s;
+
+	s = btf__str_by_offset(btf, *str_off);
+
+	if (!s)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int linker_sanity_check_btf(struct src_obj *obj)
+{
+	struct btf_type *t;
+	int i, n, err = 0;
+
+	if (!obj->btf)
+		return 0;
+
+	n = btf__type_cnt(obj->btf);
+	for (i = 1; i < n; i++) {
+		t = btf_type_by_id(obj->btf, i);
+
+		err = err ?: btf_type_visit_type_ids(t, check_btf_type_id, obj->btf);
+		err = err ?: btf_type_visit_str_offs(t, check_btf_str_off, obj->btf);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int linker_sanity_check_btf_ext(struct src_obj *obj)
+{
+	int err = 0;
+
+	if (!obj->btf_ext)
+		return 0;
+
+	/* can't use .BTF.ext without .BTF */
+	if (!obj->btf)
+		return -EINVAL;
+
+	err = err ?: btf_ext_visit_type_ids(obj->btf_ext, check_btf_type_id, obj->btf);
+	err = err ?: btf_ext_visit_str_offs(obj->btf_ext, check_btf_str_off, obj->btf);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static int init_sec(struct bpf_linker *linker, struct dst_sec *dst_sec, struct src_sec *src_sec)
+{
+	Elf_Scn *scn;
+	Elf_Data *data;
+	Elf64_Shdr *shdr;
+	int name_off;
+
+	dst_sec->sec_sz = 0;
+	dst_sec->sec_idx = 0;
+	dst_sec->ephemeral = src_sec->ephemeral;
+
+	/* ephemeral sections are just thin section shells lacking most parts */
+	if (src_sec->ephemeral)
+		return 0;
+
+	scn = elf_newscn(linker->elf);
+	if (!scn)
+		return -ENOMEM;
+	data = elf_newdata(scn);
+	if (!data)
+		return -ENOMEM;
+	shdr = elf64_getshdr(scn);
+	if (!shdr)
+		return -ENOMEM;
+
+	dst_sec->scn = scn;
+	dst_sec->shdr = shdr;
+	dst_sec->data = data;
+	dst_sec->sec_idx = elf_ndxscn(scn);
+
+	name_off = strset__add_str(linker->strtab_strs, src_sec->sec_name);
+	if (name_off < 0)
+		return name_off;
+
+	shdr->sh_name = name_off;
+	shdr->sh_type = src_sec->shdr->sh_type;
+	shdr->sh_flags = src_sec->shdr->sh_flags;
+	shdr->sh_size = 0;
+	/* sh_link and sh_info have different meaning for different types of
+	 * sections, so we leave it up to the caller code to fill them in, if
+	 * necessary
+	 */
+	shdr->sh_link = 0;
+	shdr->sh_info = 0;
+	shdr->sh_addralign = src_sec->shdr->sh_addralign;
+	shdr->sh_entsize = src_sec->shdr->sh_entsize;
+
+	data->d_type = src_sec->data->d_type;
+	data->d_size = 0;
+	data->d_buf = NULL;
+	data->d_align = src_sec->data->d_align;
+	data->d_off = 0;
+
+	return 0;
+}
+
+static struct dst_sec *find_dst_sec_by_name(struct bpf_linker *linker, const char *sec_name)
+{
+	struct dst_sec *sec;
+	int i;
+
+	for (i = 1; i < linker->sec_cnt; i++) {
+		sec = &linker->secs[i];
+
+		if (strcmp(sec->sec_name, sec_name) == 0)
+			return sec;
+	}
+
+	return NULL;
+}
+
+static bool secs_match(struct dst_sec *dst, struct src_sec *src)
+{
+	if (dst->ephemeral || src->ephemeral)
+		return true;
+
+	if (dst->shdr->sh_type != src->shdr->sh_type) {
+		pr_warn("sec %s types mismatch\n", dst->sec_name);
+		return false;
+	}
+	if (dst->shdr->sh_flags != src->shdr->sh_flags) {
+		pr_warn("sec %s flags mismatch\n", dst->sec_name);
+		return false;
+	}
+	if (dst->shdr->sh_entsize != src->shdr->sh_entsize) {
+		pr_warn("sec %s entsize mismatch\n", dst->sec_name);
+		return false;
+	}
+
+	return true;
+}
+
+static bool sec_content_is_same(struct dst_sec *dst_sec, struct src_sec *src_sec)
+{
+	if (dst_sec->sec_sz != src_sec->shdr->sh_size)
+		return false;
+	if (memcmp(dst_sec->raw_data, src_sec->data->d_buf, dst_sec->sec_sz) != 0)
+		return false;
+	return true;
+}
+
+static int extend_sec(struct bpf_linker *linker, struct dst_sec *dst, struct src_sec *src)
+{
+	void *tmp;
+	size_t dst_align, src_align;
+	size_t dst_align_sz, dst_final_sz;
+	int err;
+
+	/* Ephemeral source section doesn't contribute anything to ELF
+	 * section data.
+	 */
+	if (src->ephemeral)
+		return 0;
+
+	/* Some sections (like .maps) can contain both externs (and thus be
+	 * ephemeral) and non-externs (map definitions). So it's possible that
+	 * it has to be "upgraded" from ephemeral to non-ephemeral when the
+	 * first non-ephemeral entity appears. In such case, we add ELF
+	 * section, data, etc.
+	 */
+	if (dst->ephemeral) {
+		err = init_sec(linker, dst, src);
+		if (err)
+			return err;
+	}
+
+	dst_align = dst->shdr->sh_addralign;
+	src_align = src->shdr->sh_addralign;
+	if (dst_align == 0)
+		dst_align = 1;
+	if (dst_align < src_align)
+		dst_align = src_align;
+
+	dst_align_sz = (dst->sec_sz + dst_align - 1) / dst_align * dst_align;
+
+	/* no need to re-align final size */
+	dst_final_sz = dst_align_sz + src->shdr->sh_size;
+
+	if (src->shdr->sh_type != SHT_NOBITS) {
+		tmp = realloc(dst->raw_data, dst_final_sz);
+		if (!tmp)
+			return -ENOMEM;
+		dst->raw_data = tmp;
+
+		/* pad dst section, if it's alignment forced size increase */
+		memset(dst->raw_data + dst->sec_sz, 0, dst_align_sz - dst->sec_sz);
+		/* now copy src data at a properly aligned offset */
+		memcpy(dst->raw_data + dst_align_sz, src->data->d_buf, src->shdr->sh_size);
+	}
+
+	dst->sec_sz = dst_final_sz;
+	dst->shdr->sh_size = dst_final_sz;
+	dst->data->d_size = dst_final_sz;
+
+	dst->shdr->sh_addralign = dst_align;
+	dst->data->d_align = dst_align;
+
+	src->dst_off = dst_align_sz;
+
+	return 0;
+}
+
+static bool is_data_sec(struct src_sec *sec)
+{
+	if (!sec || sec->skipped)
+		return false;
+	/* ephemeral sections are data sections, e.g., .kconfig, .ksyms */
+	if (sec->ephemeral)
+		return true;
+	return sec->shdr->sh_type == SHT_PROGBITS || sec->shdr->sh_type == SHT_NOBITS;
+}
+
+static bool is_relo_sec(struct src_sec *sec)
+{
+	if (!sec || sec->skipped || sec->ephemeral)
+		return false;
+	return sec->shdr->sh_type == SHT_REL;
+}
+
+static int linker_append_sec_data(struct bpf_linker *linker, struct src_obj *obj)
+{
+	int i, err;
+
+	for (i = 1; i < obj->sec_cnt; i++) {
+		struct src_sec *src_sec;
+		struct dst_sec *dst_sec;
+
+		src_sec = &obj->secs[i];
+		if (!is_data_sec(src_sec))
+			continue;
+
+		dst_sec = find_dst_sec_by_name(linker, src_sec->sec_name);
+		if (!dst_sec) {
+			dst_sec = add_dst_sec(linker, src_sec->sec_name);
+			if (!dst_sec)
+				return -ENOMEM;
+			err = init_sec(linker, dst_sec, src_sec);
+			if (err) {
+				pr_warn("failed to init section '%s'\n", src_sec->sec_name);
+				return err;
+			}
+		} else {
+			if (!secs_match(dst_sec, src_sec)) {
+				pr_warn("ELF sections %s are incompatible\n", src_sec->sec_name);
+				return -1;
+			}
+
+			/* "license" and "version" sections are deduped */
+			if (strcmp(src_sec->sec_name, "license") == 0
+			    || strcmp(src_sec->sec_name, "version") == 0) {
+				if (!sec_content_is_same(dst_sec, src_sec)) {
+					pr_warn("non-identical contents of section '%s' are not supported\n", src_sec->sec_name);
+					return -EINVAL;
+				}
+				src_sec->skipped = true;
+				src_sec->dst_id = dst_sec->id;
+				continue;
+			}
+		}
+
+		/* record mapped section index */
+		src_sec->dst_id = dst_sec->id;
+
+		err = extend_sec(linker, dst_sec, src_sec);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int linker_append_elf_syms(struct bpf_linker *linker, struct src_obj *obj)
+{
+	struct src_sec *symtab = &obj->secs[obj->symtab_sec_idx];
+	Elf64_Sym *sym = symtab->data->d_buf;
+	int i, n = symtab->shdr->sh_size / symtab->shdr->sh_entsize, err;
+	int str_sec_idx = symtab->shdr->sh_link;
+	const char *sym_name;
+
+	obj->sym_map = calloc(n + 1, sizeof(*obj->sym_map));
+	if (!obj->sym_map)
+		return -ENOMEM;
+
+	for (i = 0; i < n; i++, sym++) {
+		/* We already validated all-zero symbol #0 and we already
+		 * appended it preventively to the final SYMTAB, so skip it.
+		 */
+		if (i == 0)
+			continue;
+
+		sym_name = elf_strptr(obj->elf, str_sec_idx, sym->st_name);
+		if (!sym_name) {
+			pr_warn("can't fetch symbol name for symbol #%d in '%s'\n", i, obj->filename);
+			return -EINVAL;
+		}
+
+		err = linker_append_elf_sym(linker, obj, sym, sym_name, i);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static Elf64_Sym *get_sym_by_idx(struct bpf_linker *linker, size_t sym_idx)
+{
+	struct dst_sec *symtab = &linker->secs[linker->symtab_sec_idx];
+	Elf64_Sym *syms = symtab->raw_data;
+
+	return &syms[sym_idx];
+}
+
+static struct glob_sym *find_glob_sym(struct bpf_linker *linker, const char *sym_name)
+{
+	struct glob_sym *glob_sym;
+	const char *name;
+	int i;
+
+	for (i = 0; i < linker->glob_sym_cnt; i++) {
+		glob_sym = &linker->glob_syms[i];
+		name = strset__data(linker->strtab_strs) + glob_sym->name_off;
+
+		if (strcmp(name, sym_name) == 0)
+			return glob_sym;
+	}
+
+	return NULL;
+}
+
+static struct glob_sym *add_glob_sym(struct bpf_linker *linker)
+{
+	struct glob_sym *syms, *sym;
+
+	syms = libbpf_reallocarray(linker->glob_syms, linker->glob_sym_cnt + 1,
+				   sizeof(*linker->glob_syms));
+	if (!syms)
+		return NULL;
+
+	sym = &syms[linker->glob_sym_cnt];
+	memset(sym, 0, sizeof(*sym));
+	sym->var_idx = -1;
+
+	linker->glob_syms = syms;
+	linker->glob_sym_cnt++;
+
+	return sym;
+}
+
+static bool glob_sym_btf_matches(const char *sym_name, bool exact,
+				 const struct btf *btf1, __u32 id1,
+				 const struct btf *btf2, __u32 id2)
+{
+	const struct btf_type *t1, *t2;
+	bool is_static1, is_static2;
+	const char *n1, *n2;
+	int i, n;
+
+recur:
+	n1 = n2 = NULL;
+	t1 = skip_mods_and_typedefs(btf1, id1, &id1);
+	t2 = skip_mods_and_typedefs(btf2, id2, &id2);
+
+	/* check if only one side is FWD, otherwise handle with common logic */
+	if (!exact && btf_is_fwd(t1) != btf_is_fwd(t2)) {
+		n1 = btf__str_by_offset(btf1, t1->name_off);
+		n2 = btf__str_by_offset(btf2, t2->name_off);
+		if (strcmp(n1, n2) != 0) {
+			pr_warn("global '%s': incompatible forward declaration names '%s' and '%s'\n",
+				sym_name, n1, n2);
+			return false;
+		}
+		/* validate if FWD kind matches concrete kind */
+		if (btf_is_fwd(t1)) {
+			if (btf_kflag(t1) && btf_is_union(t2))
+				return true;
+			if (!btf_kflag(t1) && btf_is_struct(t2))
+				return true;
+			pr_warn("global '%s': incompatible %s forward declaration and concrete kind %s\n",
+				sym_name, btf_kflag(t1) ? "union" : "struct", btf_kind_str(t2));
+		} else {
+			if (btf_kflag(t2) && btf_is_union(t1))
+				return true;
+			if (!btf_kflag(t2) && btf_is_struct(t1))
+				return true;
+			pr_warn("global '%s': incompatible %s forward declaration and concrete kind %s\n",
+				sym_name, btf_kflag(t2) ? "union" : "struct", btf_kind_str(t1));
+		}
+		return false;
+	}
+
+	if (btf_kind(t1) != btf_kind(t2)) {
+		pr_warn("global '%s': incompatible BTF kinds %s and %s\n",
+			sym_name, btf_kind_str(t1), btf_kind_str(t2));
+		return false;
+	}
+
+	switch (btf_kind(t1)) {
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+	case BTF_KIND_FWD:
+	case BTF_KIND_FUNC:
+	case BTF_KIND_VAR:
+		n1 = btf__str_by_offset(btf1, t1->name_off);
+		n2 = btf__str_by_offset(btf2, t2->name_off);
+		if (strcmp(n1, n2) != 0) {
+			pr_warn("global '%s': incompatible %s names '%s' and '%s'\n",
+				sym_name, btf_kind_str(t1), n1, n2);
+			return false;
+		}
+		break;
+	default:
+		break;
+	}
+
+	switch (btf_kind(t1)) {
+	case BTF_KIND_UNKN: /* void */
+	case BTF_KIND_FWD:
+		return true;
+	case BTF_KIND_INT:
+	case BTF_KIND_FLOAT:
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		/* ignore encoding for int and enum values for enum */
+		if (t1->size != t2->size) {
+			pr_warn("global '%s': incompatible %s '%s' size %u and %u\n",
+				sym_name, btf_kind_str(t1), n1, t1->size, t2->size);
+			return false;
+		}
+		return true;
+	case BTF_KIND_PTR:
+		/* just validate overall shape of the referenced type, so no
+		 * contents comparison for struct/union, and allowd fwd vs
+		 * struct/union
+		 */
+		exact = false;
+		id1 = t1->type;
+		id2 = t2->type;
+		goto recur;
+	case BTF_KIND_ARRAY:
+		/* ignore index type and array size */
+		id1 = btf_array(t1)->type;
+		id2 = btf_array(t2)->type;
+		goto recur;
+	case BTF_KIND_FUNC:
+		/* extern and global linkages are compatible */
+		is_static1 = btf_func_linkage(t1) == BTF_FUNC_STATIC;
+		is_static2 = btf_func_linkage(t2) == BTF_FUNC_STATIC;
+		if (is_static1 != is_static2) {
+			pr_warn("global '%s': incompatible func '%s' linkage\n", sym_name, n1);
+			return false;
+		}
+
+		id1 = t1->type;
+		id2 = t2->type;
+		goto recur;
+	case BTF_KIND_VAR:
+		/* extern and global linkages are compatible */
+		is_static1 = btf_var(t1)->linkage == BTF_VAR_STATIC;
+		is_static2 = btf_var(t2)->linkage == BTF_VAR_STATIC;
+		if (is_static1 != is_static2) {
+			pr_warn("global '%s': incompatible var '%s' linkage\n", sym_name, n1);
+			return false;
+		}
+
+		id1 = t1->type;
+		id2 = t2->type;
+		goto recur;
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		const struct btf_member *m1, *m2;
+
+		if (!exact)
+			return true;
+
+		if (btf_vlen(t1) != btf_vlen(t2)) {
+			pr_warn("global '%s': incompatible number of %s fields %u and %u\n",
+				sym_name, btf_kind_str(t1), btf_vlen(t1), btf_vlen(t2));
+			return false;
+		}
+
+		n = btf_vlen(t1);
+		m1 = btf_members(t1);
+		m2 = btf_members(t2);
+		for (i = 0; i < n; i++, m1++, m2++) {
+			n1 = btf__str_by_offset(btf1, m1->name_off);
+			n2 = btf__str_by_offset(btf2, m2->name_off);
+			if (strcmp(n1, n2) != 0) {
+				pr_warn("global '%s': incompatible field #%d names '%s' and '%s'\n",
+					sym_name, i, n1, n2);
+				return false;
+			}
+			if (m1->offset != m2->offset) {
+				pr_warn("global '%s': incompatible field #%d ('%s') offsets\n",
+					sym_name, i, n1);
+				return false;
+			}
+			if (!glob_sym_btf_matches(sym_name, exact, btf1, m1->type, btf2, m2->type))
+				return false;
+		}
+
+		return true;
+	}
+	case BTF_KIND_FUNC_PROTO: {
+		const struct btf_param *m1, *m2;
+
+		if (btf_vlen(t1) != btf_vlen(t2)) {
+			pr_warn("global '%s': incompatible number of %s params %u and %u\n",
+				sym_name, btf_kind_str(t1), btf_vlen(t1), btf_vlen(t2));
+			return false;
+		}
+
+		n = btf_vlen(t1);
+		m1 = btf_params(t1);
+		m2 = btf_params(t2);
+		for (i = 0; i < n; i++, m1++, m2++) {
+			/* ignore func arg names */
+			if (!glob_sym_btf_matches(sym_name, exact, btf1, m1->type, btf2, m2->type))
+				return false;
+		}
+
+		/* now check return type as well */
+		id1 = t1->type;
+		id2 = t2->type;
+		goto recur;
+	}
+
+	/* skip_mods_and_typedefs() make this impossible */
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_CONST:
+	case BTF_KIND_RESTRICT:
+	/* DATASECs are never compared with each other */
+	case BTF_KIND_DATASEC:
+	default:
+		pr_warn("global '%s': unsupported BTF kind %s\n",
+			sym_name, btf_kind_str(t1));
+		return false;
+	}
+}
+
+static bool map_defs_match(const char *sym_name,
+			   const struct btf *main_btf,
+			   const struct btf_map_def *main_def,
+			   const struct btf_map_def *main_inner_def,
+			   const struct btf *extra_btf,
+			   const struct btf_map_def *extra_def,
+			   const struct btf_map_def *extra_inner_def)
+{
+	const char *reason;
+
+	if (main_def->map_type != extra_def->map_type) {
+		reason = "type";
+		goto mismatch;
+	}
+
+	/* check key type/size match */
+	if (main_def->key_size != extra_def->key_size) {
+		reason = "key_size";
+		goto mismatch;
+	}
+	if (!!main_def->key_type_id != !!extra_def->key_type_id) {
+		reason = "key type";
+		goto mismatch;
+	}
+	if ((main_def->parts & MAP_DEF_KEY_TYPE)
+	     && !glob_sym_btf_matches(sym_name, true /*exact*/,
+				      main_btf, main_def->key_type_id,
+				      extra_btf, extra_def->key_type_id)) {
+		reason = "key type";
+		goto mismatch;
+	}
+
+	/* validate value type/size match */
+	if (main_def->value_size != extra_def->value_size) {
+		reason = "value_size";
+		goto mismatch;
+	}
+	if (!!main_def->value_type_id != !!extra_def->value_type_id) {
+		reason = "value type";
+		goto mismatch;
+	}
+	if ((main_def->parts & MAP_DEF_VALUE_TYPE)
+	     && !glob_sym_btf_matches(sym_name, true /*exact*/,
+				      main_btf, main_def->value_type_id,
+				      extra_btf, extra_def->value_type_id)) {
+		reason = "key type";
+		goto mismatch;
+	}
+
+	if (main_def->max_entries != extra_def->max_entries) {
+		reason = "max_entries";
+		goto mismatch;
+	}
+	if (main_def->map_flags != extra_def->map_flags) {
+		reason = "map_flags";
+		goto mismatch;
+	}
+	if (main_def->numa_node != extra_def->numa_node) {
+		reason = "numa_node";
+		goto mismatch;
+	}
+	if (main_def->pinning != extra_def->pinning) {
+		reason = "pinning";
+		goto mismatch;
+	}
+
+	if ((main_def->parts & MAP_DEF_INNER_MAP) != (extra_def->parts & MAP_DEF_INNER_MAP)) {
+		reason = "inner map";
+		goto mismatch;
+	}
+
+	if (main_def->parts & MAP_DEF_INNER_MAP) {
+		char inner_map_name[128];
+
+		snprintf(inner_map_name, sizeof(inner_map_name), "%s.inner", sym_name);
+
+		return map_defs_match(inner_map_name,
+				      main_btf, main_inner_def, NULL,
+				      extra_btf, extra_inner_def, NULL);
+	}
+
+	return true;
+
+mismatch:
+	pr_warn("global '%s': map %s mismatch\n", sym_name, reason);
+	return false;
+}
+
+static bool glob_map_defs_match(const char *sym_name,
+				struct bpf_linker *linker, struct glob_sym *glob_sym,
+				struct src_obj *obj, Elf64_Sym *sym, int btf_id)
+{
+	struct btf_map_def dst_def = {}, dst_inner_def = {};
+	struct btf_map_def src_def = {}, src_inner_def = {};
+	const struct btf_type *t;
+	int err;
+
+	t = btf__type_by_id(obj->btf, btf_id);
+	if (!btf_is_var(t)) {
+		pr_warn("global '%s': invalid map definition type [%d]\n", sym_name, btf_id);
+		return false;
+	}
+	t = skip_mods_and_typedefs(obj->btf, t->type, NULL);
+
+	err = parse_btf_map_def(sym_name, obj->btf, t, true /*strict*/, &src_def, &src_inner_def);
+	if (err) {
+		pr_warn("global '%s': invalid map definition\n", sym_name);
+		return false;
+	}
+
+	/* re-parse existing map definition */
+	t = btf__type_by_id(linker->btf, glob_sym->btf_id);
+	t = skip_mods_and_typedefs(linker->btf, t->type, NULL);
+	err = parse_btf_map_def(sym_name, linker->btf, t, true /*strict*/, &dst_def, &dst_inner_def);
+	if (err) {
+		/* this should not happen, because we already validated it */
+		pr_warn("global '%s': invalid dst map definition\n", sym_name);
+		return false;
+	}
+
+	/* Currently extern map definition has to be complete and match
+	 * concrete map definition exactly. This restriction might be lifted
+	 * in the future.
+	 */
+	return map_defs_match(sym_name, linker->btf, &dst_def, &dst_inner_def,
+			      obj->btf, &src_def, &src_inner_def);
+}
+
+static bool glob_syms_match(const char *sym_name,
+			    struct bpf_linker *linker, struct glob_sym *glob_sym,
+			    struct src_obj *obj, Elf64_Sym *sym, size_t sym_idx, int btf_id)
+{
+	const struct btf_type *src_t;
+
+	/* if we are dealing with externs, BTF types describing both global
+	 * and extern VARs/FUNCs should be completely present in all files
+	 */
+	if (!glob_sym->btf_id || !btf_id) {
+		pr_warn("BTF info is missing for global symbol '%s'\n", sym_name);
+		return false;
+	}
+
+	src_t = btf__type_by_id(obj->btf, btf_id);
+	if (!btf_is_var(src_t) && !btf_is_func(src_t)) {
+		pr_warn("only extern variables and functions are supported, but got '%s' for '%s'\n",
+			btf_kind_str(src_t), sym_name);
+		return false;
+	}
+
+	/* deal with .maps definitions specially */
+	if (glob_sym->sec_id && strcmp(linker->secs[glob_sym->sec_id].sec_name, MAPS_ELF_SEC) == 0)
+		return glob_map_defs_match(sym_name, linker, glob_sym, obj, sym, btf_id);
+
+	if (!glob_sym_btf_matches(sym_name, true /*exact*/,
+				  linker->btf, glob_sym->btf_id, obj->btf, btf_id))
+		return false;
+
+	return true;
+}
+
+static bool btf_is_non_static(const struct btf_type *t)
+{
+	return (btf_is_var(t) && btf_var(t)->linkage != BTF_VAR_STATIC)
+	       || (btf_is_func(t) && btf_func_linkage(t) != BTF_FUNC_STATIC);
+}
+
+static int find_glob_sym_btf(struct src_obj *obj, Elf64_Sym *sym, const char *sym_name,
+			     int *out_btf_sec_id, int *out_btf_id)
+{
+	int i, j, n, m, btf_id = 0;
+	const struct btf_type *t;
+	const struct btf_var_secinfo *vi;
+	const char *name;
+
+	if (!obj->btf) {
+		pr_warn("failed to find BTF info for object '%s'\n", obj->filename);
+		return -EINVAL;
+	}
+
+	n = btf__type_cnt(obj->btf);
+	for (i = 1; i < n; i++) {
+		t = btf__type_by_id(obj->btf, i);
+
+		/* some global and extern FUNCs and VARs might not be associated with any
+		 * DATASEC, so try to detect them in the same pass
+		 */
+		if (btf_is_non_static(t)) {
+			name = btf__str_by_offset(obj->btf, t->name_off);
+			if (strcmp(name, sym_name) != 0)
+				continue;
+
+			/* remember and still try to find DATASEC */
+			btf_id = i;
+			continue;
+		}
+
+		if (!btf_is_datasec(t))
+			continue;
+
+		vi = btf_var_secinfos(t);
+		for (j = 0, m = btf_vlen(t); j < m; j++, vi++) {
+			t = btf__type_by_id(obj->btf, vi->type);
+			name = btf__str_by_offset(obj->btf, t->name_off);
+
+			if (strcmp(name, sym_name) != 0)
+				continue;
+			if (btf_is_var(t) && btf_var(t)->linkage == BTF_VAR_STATIC)
+				continue;
+			if (btf_is_func(t) && btf_func_linkage(t) == BTF_FUNC_STATIC)
+				continue;
+
+			if (btf_id && btf_id != vi->type) {
+				pr_warn("global/extern '%s' BTF is ambiguous: both types #%d and #%u match\n",
+					sym_name, btf_id, vi->type);
+				return -EINVAL;
+			}
+
+			*out_btf_sec_id = i;
+			*out_btf_id = vi->type;
+
+			return 0;
+		}
+	}
+
+	/* free-floating extern or global FUNC */
+	if (btf_id) {
+		*out_btf_sec_id = 0;
+		*out_btf_id = btf_id;
+		return 0;
+	}
+
+	pr_warn("failed to find BTF info for global/extern symbol '%s'\n", sym_name);
+	return -ENOENT;
+}
+
+static struct src_sec *find_src_sec_by_name(struct src_obj *obj, const char *sec_name)
+{
+	struct src_sec *sec;
+	int i;
+
+	for (i = 1; i < obj->sec_cnt; i++) {
+		sec = &obj->secs[i];
+
+		if (strcmp(sec->sec_name, sec_name) == 0)
+			return sec;
+	}
+
+	return NULL;
+}
+
+static int complete_extern_btf_info(struct btf *dst_btf, int dst_id,
+				    struct btf *src_btf, int src_id)
+{
+	struct btf_type *dst_t = btf_type_by_id(dst_btf, dst_id);
+	struct btf_type *src_t = btf_type_by_id(src_btf, src_id);
+	struct btf_param *src_p, *dst_p;
+	const char *s;
+	int i, n, off;
+
+	/* We already made sure that source and destination types (FUNC or
+	 * VAR) match in terms of types and argument names.
+	 */
+	if (btf_is_var(dst_t)) {
+		btf_var(dst_t)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
+		return 0;
+	}
+
+	dst_t->info = btf_type_info(BTF_KIND_FUNC, BTF_FUNC_GLOBAL, 0);
+
+	/* now onto FUNC_PROTO types */
+	src_t = btf_type_by_id(src_btf, src_t->type);
+	dst_t = btf_type_by_id(dst_btf, dst_t->type);
+
+	/* Fill in all the argument names, which for extern FUNCs are missing.
+	 * We'll end up with two copies of FUNCs/VARs for externs, but that
+	 * will be taken care of by BTF dedup at the very end.
+	 * It might be that BTF types for extern in one file has less/more BTF
+	 * information (e.g., FWD instead of full STRUCT/UNION information),
+	 * but that should be (in most cases, subject to BTF dedup rules)
+	 * handled and resolved by BTF dedup algorithm as well, so we won't
+	 * worry about it. Our only job is to make sure that argument names
+	 * are populated on both sides, otherwise BTF dedup will pedantically
+	 * consider them different.
+	 */
+	src_p = btf_params(src_t);
+	dst_p = btf_params(dst_t);
+	for (i = 0, n = btf_vlen(dst_t); i < n; i++, src_p++, dst_p++) {
+		if (!src_p->name_off)
+			continue;
+
+		/* src_btf has more complete info, so add name to dst_btf */
+		s = btf__str_by_offset(src_btf, src_p->name_off);
+		off = btf__add_str(dst_btf, s);
+		if (off < 0)
+			return off;
+		dst_p->name_off = off;
+	}
+	return 0;
+}
+
+static void sym_update_bind(Elf64_Sym *sym, int sym_bind)
+{
+	sym->st_info = ELF64_ST_INFO(sym_bind, ELF64_ST_TYPE(sym->st_info));
+}
+
+static void sym_update_type(Elf64_Sym *sym, int sym_type)
+{
+	sym->st_info = ELF64_ST_INFO(ELF64_ST_BIND(sym->st_info), sym_type);
+}
+
+static void sym_update_visibility(Elf64_Sym *sym, int sym_vis)
+{
+	/* libelf doesn't provide setters for ST_VISIBILITY,
+	 * but it is stored in the lower 2 bits of st_other
+	 */
+	sym->st_other &= ~0x03;
+	sym->st_other |= sym_vis;
+}
+
+static int linker_append_elf_sym(struct bpf_linker *linker, struct src_obj *obj,
+				 Elf64_Sym *sym, const char *sym_name, int src_sym_idx)
+{
+	struct src_sec *src_sec = NULL;
+	struct dst_sec *dst_sec = NULL;
+	struct glob_sym *glob_sym = NULL;
+	int name_off, sym_type, sym_bind, sym_vis, err;
+	int btf_sec_id = 0, btf_id = 0;
+	size_t dst_sym_idx;
+	Elf64_Sym *dst_sym;
+	bool sym_is_extern;
+
+	sym_type = ELF64_ST_TYPE(sym->st_info);
+	sym_bind = ELF64_ST_BIND(sym->st_info);
+	sym_vis = ELF64_ST_VISIBILITY(sym->st_other);
+	sym_is_extern = sym->st_shndx == SHN_UNDEF;
+
+	if (sym_is_extern) {
+		if (!obj->btf) {
+			pr_warn("externs without BTF info are not supported\n");
+			return -ENOTSUP;
+		}
+	} else if (sym->st_shndx < SHN_LORESERVE) {
+		src_sec = &obj->secs[sym->st_shndx];
+		if (src_sec->skipped)
+			return 0;
+		dst_sec = &linker->secs[src_sec->dst_id];
+
+		/* allow only one STT_SECTION symbol per section */
+		if (sym_type == STT_SECTION && dst_sec->sec_sym_idx) {
+			obj->sym_map[src_sym_idx] = dst_sec->sec_sym_idx;
+			return 0;
+		}
+	}
+
+	if (sym_bind == STB_LOCAL)
+		goto add_sym;
+
+	/* find matching BTF info */
+	err = find_glob_sym_btf(obj, sym, sym_name, &btf_sec_id, &btf_id);
+	if (err)
+		return err;
+
+	if (sym_is_extern && btf_sec_id) {
+		const char *sec_name = NULL;
+		const struct btf_type *t;
+
+		t = btf__type_by_id(obj->btf, btf_sec_id);
+		sec_name = btf__str_by_offset(obj->btf, t->name_off);
+
+		/* Clang puts unannotated extern vars into
+		 * '.extern' BTF DATASEC. Treat them the same
+		 * as unannotated extern funcs (which are
+		 * currently not put into any DATASECs).
+		 * Those don't have associated src_sec/dst_sec.
+		 */
+		if (strcmp(sec_name, BTF_EXTERN_SEC) != 0) {
+			src_sec = find_src_sec_by_name(obj, sec_name);
+			if (!src_sec) {
+				pr_warn("failed to find matching ELF sec '%s'\n", sec_name);
+				return -ENOENT;
+			}
+			dst_sec = &linker->secs[src_sec->dst_id];
+		}
+	}
+
+	glob_sym = find_glob_sym(linker, sym_name);
+	if (glob_sym) {
+		/* Preventively resolve to existing symbol. This is
+		 * needed for further relocation symbol remapping in
+		 * the next step of linking.
+		 */
+		obj->sym_map[src_sym_idx] = glob_sym->sym_idx;
+
+		/* If both symbols are non-externs, at least one of
+		 * them has to be STB_WEAK, otherwise they are in
+		 * a conflict with each other.
+		 */
+		if (!sym_is_extern && !glob_sym->is_extern
+		    && !glob_sym->is_weak && sym_bind != STB_WEAK) {
+			pr_warn("conflicting non-weak symbol #%d (%s) definition in '%s'\n",
+				src_sym_idx, sym_name, obj->filename);
+			return -EINVAL;
+		}
+
+		if (!glob_syms_match(sym_name, linker, glob_sym, obj, sym, src_sym_idx, btf_id))
+			return -EINVAL;
+
+		dst_sym = get_sym_by_idx(linker, glob_sym->sym_idx);
+
+		/* If new symbol is strong, then force dst_sym to be strong as
+		 * well; this way a mix of weak and non-weak extern
+		 * definitions will end up being strong.
+		 */
+		if (sym_bind == STB_GLOBAL) {
+			/* We still need to preserve type (NOTYPE or
+			 * OBJECT/FUNC, depending on whether the symbol is
+			 * extern or not)
+			 */
+			sym_update_bind(dst_sym, STB_GLOBAL);
+			glob_sym->is_weak = false;
+		}
+
+		/* Non-default visibility is "contaminating", with stricter
+		 * visibility overwriting more permissive ones, even if more
+		 * permissive visibility comes from just an extern definition.
+		 * Currently only STV_DEFAULT and STV_HIDDEN are allowed and
+		 * ensured by ELF symbol sanity checks above.
+		 */
+		if (sym_vis > ELF64_ST_VISIBILITY(dst_sym->st_other))
+			sym_update_visibility(dst_sym, sym_vis);
+
+		/* If the new symbol is extern, then regardless if
+		 * existing symbol is extern or resolved global, just
+		 * keep the existing one untouched.
+		 */
+		if (sym_is_extern)
+			return 0;
+
+		/* If existing symbol is a strong resolved symbol, bail out,
+		 * because we lost resolution battle have nothing to
+		 * contribute. We already checked abover that there is no
+		 * strong-strong conflict. We also already tightened binding
+		 * and visibility, so nothing else to contribute at that point.
+		 */
+		if (!glob_sym->is_extern && sym_bind == STB_WEAK)
+			return 0;
+
+		/* At this point, new symbol is strong non-extern,
+		 * so overwrite glob_sym with new symbol information.
+		 * Preserve binding and visibility.
+		 */
+		sym_update_type(dst_sym, sym_type);
+		dst_sym->st_shndx = dst_sec->sec_idx;
+		dst_sym->st_value = src_sec->dst_off + sym->st_value;
+		dst_sym->st_size = sym->st_size;
+
+		/* see comment below about dst_sec->id vs dst_sec->sec_idx */
+		glob_sym->sec_id = dst_sec->id;
+		glob_sym->is_extern = false;
+
+		if (complete_extern_btf_info(linker->btf, glob_sym->btf_id,
+					     obj->btf, btf_id))
+			return -EINVAL;
+
+		/* request updating VAR's/FUNC's underlying BTF type when appending BTF type */
+		glob_sym->underlying_btf_id = 0;
+
+		obj->sym_map[src_sym_idx] = glob_sym->sym_idx;
+		return 0;
+	}
+
+add_sym:
+	name_off = strset__add_str(linker->strtab_strs, sym_name);
+	if (name_off < 0)
+		return name_off;
+
+	dst_sym = add_new_sym(linker, &dst_sym_idx);
+	if (!dst_sym)
+		return -ENOMEM;
+
+	dst_sym->st_name = name_off;
+	dst_sym->st_info = sym->st_info;
+	dst_sym->st_other = sym->st_other;
+	dst_sym->st_shndx = dst_sec ? dst_sec->sec_idx : sym->st_shndx;
+	dst_sym->st_value = (src_sec ? src_sec->dst_off : 0) + sym->st_value;
+	dst_sym->st_size = sym->st_size;
+
+	obj->sym_map[src_sym_idx] = dst_sym_idx;
+
+	if (sym_type == STT_SECTION && dst_sym) {
+		dst_sec->sec_sym_idx = dst_sym_idx;
+		dst_sym->st_value = 0;
+	}
+
+	if (sym_bind != STB_LOCAL) {
+		glob_sym = add_glob_sym(linker);
+		if (!glob_sym)
+			return -ENOMEM;
+
+		glob_sym->sym_idx = dst_sym_idx;
+		/* we use dst_sec->id (and not dst_sec->sec_idx), because
+		 * ephemeral sections (.kconfig, .ksyms, etc) don't have
+		 * sec_idx (as they don't have corresponding ELF section), but
+		 * still have id. .extern doesn't have even ephemeral section
+		 * associated with it, so dst_sec->id == dst_sec->sec_idx == 0.
+		 */
+		glob_sym->sec_id = dst_sec ? dst_sec->id : 0;
+		glob_sym->name_off = name_off;
+		/* we will fill btf_id in during BTF merging step */
+		glob_sym->btf_id = 0;
+		glob_sym->is_extern = sym_is_extern;
+		glob_sym->is_weak = sym_bind == STB_WEAK;
+	}
+
+	return 0;
+}
+
+static int linker_append_elf_relos(struct bpf_linker *linker, struct src_obj *obj)
+{
+	struct src_sec *src_symtab = &obj->secs[obj->symtab_sec_idx];
+	struct dst_sec *dst_symtab;
+	int i, err;
+
+	for (i = 1; i < obj->sec_cnt; i++) {
+		struct src_sec *src_sec, *src_linked_sec;
+		struct dst_sec *dst_sec, *dst_linked_sec;
+		Elf64_Rel *src_rel, *dst_rel;
+		int j, n;
+
+		src_sec = &obj->secs[i];
+		if (!is_relo_sec(src_sec))
+			continue;
+
+		/* shdr->sh_info points to relocatable section */
+		src_linked_sec = &obj->secs[src_sec->shdr->sh_info];
+		if (src_linked_sec->skipped)
+			continue;
+
+		dst_sec = find_dst_sec_by_name(linker, src_sec->sec_name);
+		if (!dst_sec) {
+			dst_sec = add_dst_sec(linker, src_sec->sec_name);
+			if (!dst_sec)
+				return -ENOMEM;
+			err = init_sec(linker, dst_sec, src_sec);
+			if (err) {
+				pr_warn("failed to init section '%s'\n", src_sec->sec_name);
+				return err;
+			}
+		} else if (!secs_match(dst_sec, src_sec)) {
+			pr_warn("sections %s are not compatible\n", src_sec->sec_name);
+			return -1;
+		}
+
+		/* add_dst_sec() above could have invalidated linker->secs */
+		dst_symtab = &linker->secs[linker->symtab_sec_idx];
+
+		/* shdr->sh_link points to SYMTAB */
+		dst_sec->shdr->sh_link = linker->symtab_sec_idx;
+
+		/* shdr->sh_info points to relocated section */
+		dst_linked_sec = &linker->secs[src_linked_sec->dst_id];
+		dst_sec->shdr->sh_info = dst_linked_sec->sec_idx;
+
+		src_sec->dst_id = dst_sec->id;
+		err = extend_sec(linker, dst_sec, src_sec);
+		if (err)
+			return err;
+
+		src_rel = src_sec->data->d_buf;
+		dst_rel = dst_sec->raw_data + src_sec->dst_off;
+		n = src_sec->shdr->sh_size / src_sec->shdr->sh_entsize;
+		for (j = 0; j < n; j++, src_rel++, dst_rel++) {
+			size_t src_sym_idx = ELF64_R_SYM(src_rel->r_info);
+			size_t sym_type = ELF64_R_TYPE(src_rel->r_info);
+			Elf64_Sym *src_sym, *dst_sym;
+			size_t dst_sym_idx;
+
+			src_sym_idx = ELF64_R_SYM(src_rel->r_info);
+			src_sym = src_symtab->data->d_buf + sizeof(*src_sym) * src_sym_idx;
+
+			dst_sym_idx = obj->sym_map[src_sym_idx];
+			dst_sym = dst_symtab->raw_data + sizeof(*dst_sym) * dst_sym_idx;
+			dst_rel->r_offset += src_linked_sec->dst_off;
+			sym_type = ELF64_R_TYPE(src_rel->r_info);
+			dst_rel->r_info = ELF64_R_INFO(dst_sym_idx, sym_type);
+
+			if (ELF64_ST_TYPE(src_sym->st_info) == STT_SECTION) {
+				struct src_sec *sec = &obj->secs[src_sym->st_shndx];
+				struct bpf_insn *insn;
+
+				if (src_linked_sec->shdr->sh_flags & SHF_EXECINSTR) {
+					/* calls to the very first static function inside
+					 * .text section at offset 0 will
+					 * reference section symbol, not the
+					 * function symbol. Fix that up,
+					 * otherwise it won't be possible to
+					 * relocate calls to two different
+					 * static functions with the same name
+					 * (rom two different object files)
+					 */
+					insn = dst_linked_sec->raw_data + dst_rel->r_offset;
+					if (insn->code == (BPF_JMP | BPF_CALL))
+						insn->imm += sec->dst_off / sizeof(struct bpf_insn);
+					else
+						insn->imm += sec->dst_off;
+				} else {
+					pr_warn("relocation against STT_SECTION in non-exec section is not supported!\n");
+					return -EINVAL;
+				}
+			}
+
+		}
+	}
+
+	return 0;
+}
+
+static Elf64_Sym *find_sym_by_name(struct src_obj *obj, size_t sec_idx,
+				   int sym_type, const char *sym_name)
+{
+	struct src_sec *symtab = &obj->secs[obj->symtab_sec_idx];
+	Elf64_Sym *sym = symtab->data->d_buf;
+	int i, n = symtab->shdr->sh_size / symtab->shdr->sh_entsize;
+	int str_sec_idx = symtab->shdr->sh_link;
+	const char *name;
+
+	for (i = 0; i < n; i++, sym++) {
+		if (sym->st_shndx != sec_idx)
+			continue;
+		if (ELF64_ST_TYPE(sym->st_info) != sym_type)
+			continue;
+
+		name = elf_strptr(obj->elf, str_sec_idx, sym->st_name);
+		if (!name)
+			return NULL;
+
+		if (strcmp(sym_name, name) != 0)
+			continue;
+
+		return sym;
+	}
+
+	return NULL;
+}
+
+static int linker_fixup_btf(struct src_obj *obj)
+{
+	const char *sec_name;
+	struct src_sec *sec;
+	int i, j, n, m;
+
+	if (!obj->btf)
+		return 0;
+
+	n = btf__type_cnt(obj->btf);
+	for (i = 1; i < n; i++) {
+		struct btf_var_secinfo *vi;
+		struct btf_type *t;
+
+		t = btf_type_by_id(obj->btf, i);
+		if (btf_kind(t) != BTF_KIND_DATASEC)
+			continue;
+
+		sec_name = btf__str_by_offset(obj->btf, t->name_off);
+		sec = find_src_sec_by_name(obj, sec_name);
+		if (sec) {
+			/* record actual section size, unless ephemeral */
+			if (sec->shdr)
+				t->size = sec->shdr->sh_size;
+		} else {
+			/* BTF can have some sections that are not represented
+			 * in ELF, e.g., .kconfig, .ksyms, .extern, which are used
+			 * for special extern variables.
+			 *
+			 * For all but one such special (ephemeral)
+			 * sections, we pre-create "section shells" to be able
+			 * to keep track of extra per-section metadata later
+			 * (e.g., those BTF extern variables).
+			 *
+			 * .extern is even more special, though, because it
+			 * contains extern variables that need to be resolved
+			 * by static linker, not libbpf and kernel. When such
+			 * externs are resolved, we are going to remove them
+			 * from .extern BTF section and might end up not
+			 * needing it at all. Each resolved extern should have
+			 * matching non-extern VAR/FUNC in other sections.
+			 *
+			 * We do support leaving some of the externs
+			 * unresolved, though, to support cases of building
+			 * libraries, which will later be linked against final
+			 * BPF applications. So if at finalization we still
+			 * see unresolved externs, we'll create .extern
+			 * section on our own.
+			 */
+			if (strcmp(sec_name, BTF_EXTERN_SEC) == 0)
+				continue;
+
+			sec = add_src_sec(obj, sec_name);
+			if (!sec)
+				return -ENOMEM;
+
+			sec->ephemeral = true;
+			sec->sec_idx = 0; /* will match UNDEF shndx in ELF */
+		}
+
+		/* remember ELF section and its BTF type ID match */
+		sec->sec_type_id = i;
+
+		/* fix up variable offsets */
+		vi = btf_var_secinfos(t);
+		for (j = 0, m = btf_vlen(t); j < m; j++, vi++) {
+			const struct btf_type *vt = btf__type_by_id(obj->btf, vi->type);
+			const char *var_name = btf__str_by_offset(obj->btf, vt->name_off);
+			int var_linkage = btf_var(vt)->linkage;
+			Elf64_Sym *sym;
+
+			/* no need to patch up static or extern vars */
+			if (var_linkage != BTF_VAR_GLOBAL_ALLOCATED)
+				continue;
+
+			sym = find_sym_by_name(obj, sec->sec_idx, STT_OBJECT, var_name);
+			if (!sym) {
+				pr_warn("failed to find symbol for variable '%s' in section '%s'\n", var_name, sec_name);
+				return -ENOENT;
+			}
+
+			vi->offset = sym->st_value;
+		}
+	}
+
+	return 0;
+}
+
+static int remap_type_id(__u32 *type_id, void *ctx)
+{
+	int *id_map = ctx;
+	int new_id = id_map[*type_id];
+
+	/* Error out if the type wasn't remapped. Ignore VOID which stays VOID. */
+	if (new_id == 0 && *type_id != 0) {
+		pr_warn("failed to find new ID mapping for original BTF type ID %u\n", *type_id);
+		return -EINVAL;
+	}
+
+	*type_id = id_map[*type_id];
+
+	return 0;
+}
+
+static int linker_append_btf(struct bpf_linker *linker, struct src_obj *obj)
+{
+	const struct btf_type *t;
+	int i, j, n, start_id, id;
+	const char *name;
+
+	if (!obj->btf)
+		return 0;
+
+	start_id = btf__type_cnt(linker->btf);
+	n = btf__type_cnt(obj->btf);
+
+	obj->btf_type_map = calloc(n + 1, sizeof(int));
+	if (!obj->btf_type_map)
+		return -ENOMEM;
+
+	for (i = 1; i < n; i++) {
+		struct glob_sym *glob_sym = NULL;
+
+		t = btf__type_by_id(obj->btf, i);
+
+		/* DATASECs are handled specially below */
+		if (btf_kind(t) == BTF_KIND_DATASEC)
+			continue;
+
+		if (btf_is_non_static(t)) {
+			/* there should be glob_sym already */
+			name = btf__str_by_offset(obj->btf, t->name_off);
+			glob_sym = find_glob_sym(linker, name);
+
+			/* VARs without corresponding glob_sym are those that
+			 * belong to skipped/deduplicated sections (i.e.,
+			 * license and version), so just skip them
+			 */
+			if (!glob_sym)
+				continue;
+
+			/* linker_append_elf_sym() might have requested
+			 * updating underlying type ID, if extern was resolved
+			 * to strong symbol or weak got upgraded to non-weak
+			 */
+			if (glob_sym->underlying_btf_id == 0)
+				glob_sym->underlying_btf_id = -t->type;
+
+			/* globals from previous object files that match our
+			 * VAR/FUNC already have a corresponding associated
+			 * BTF type, so just make sure to use it
+			 */
+			if (glob_sym->btf_id) {
+				/* reuse existing BTF type for global var/func */
+				obj->btf_type_map[i] = glob_sym->btf_id;
+				continue;
+			}
+		}
+
+		id = btf__add_type(linker->btf, obj->btf, t);
+		if (id < 0) {
+			pr_warn("failed to append BTF type #%d from file '%s'\n", i, obj->filename);
+			return id;
+		}
+
+		obj->btf_type_map[i] = id;
+
+		/* record just appended BTF type for var/func */
+		if (glob_sym) {
+			glob_sym->btf_id = id;
+			glob_sym->underlying_btf_id = -t->type;
+		}
+	}
+
+	/* remap all the types except DATASECs */
+	n = btf__type_cnt(linker->btf);
+	for (i = start_id; i < n; i++) {
+		struct btf_type *dst_t = btf_type_by_id(linker->btf, i);
+
+		if (btf_type_visit_type_ids(dst_t, remap_type_id, obj->btf_type_map))
+			return -EINVAL;
+	}
+
+	/* Rewrite VAR/FUNC underlying types (i.e., FUNC's FUNC_PROTO and VAR's
+	 * actual type), if necessary
+	 */
+	for (i = 0; i < linker->glob_sym_cnt; i++) {
+		struct glob_sym *glob_sym = &linker->glob_syms[i];
+		struct btf_type *glob_t;
+
+		if (glob_sym->underlying_btf_id >= 0)
+			continue;
+
+		glob_sym->underlying_btf_id = obj->btf_type_map[-glob_sym->underlying_btf_id];
+
+		glob_t = btf_type_by_id(linker->btf, glob_sym->btf_id);
+		glob_t->type = glob_sym->underlying_btf_id;
+	}
+
+	/* append DATASEC info */
+	for (i = 1; i < obj->sec_cnt; i++) {
+		struct src_sec *src_sec;
+		struct dst_sec *dst_sec;
+		const struct btf_var_secinfo *src_var;
+		struct btf_var_secinfo *dst_var;
+
+		src_sec = &obj->secs[i];
+		if (!src_sec->sec_type_id || src_sec->skipped)
+			continue;
+		dst_sec = &linker->secs[src_sec->dst_id];
+
+		/* Mark section as having BTF regardless of the presence of
+		 * variables. In some cases compiler might generate empty BTF
+		 * with no variables information. E.g., when promoting local
+		 * array/structure variable initial values and BPF object
+		 * file otherwise has no read-only static variables in
+		 * .rodata. We need to preserve such empty BTF and just set
+		 * correct section size.
+		 */
+		dst_sec->has_btf = true;
+
+		t = btf__type_by_id(obj->btf, src_sec->sec_type_id);
+		src_var = btf_var_secinfos(t);
+		n = btf_vlen(t);
+		for (j = 0; j < n; j++, src_var++) {
+			void *sec_vars = dst_sec->sec_vars;
+			int new_id = obj->btf_type_map[src_var->type];
+			struct glob_sym *glob_sym = NULL;
+
+			t = btf_type_by_id(linker->btf, new_id);
+			if (btf_is_non_static(t)) {
+				name = btf__str_by_offset(linker->btf, t->name_off);
+				glob_sym = find_glob_sym(linker, name);
+				if (glob_sym->sec_id != dst_sec->id) {
+					pr_warn("global '%s': section mismatch %d vs %d\n",
+						name, glob_sym->sec_id, dst_sec->id);
+					return -EINVAL;
+				}
+			}
+
+			/* If there is already a member (VAR or FUNC) mapped
+			 * to the same type, don't add a duplicate entry.
+			 * This will happen when multiple object files define
+			 * the same extern VARs/FUNCs.
+			 */
+			if (glob_sym && glob_sym->var_idx >= 0) {
+				__s64 sz;
+
+				dst_var = &dst_sec->sec_vars[glob_sym->var_idx];
+				/* Because underlying BTF type might have
+				 * changed, so might its size have changed, so
+				 * re-calculate and update it in sec_var.
+				 */
+				sz = btf__resolve_size(linker->btf, glob_sym->underlying_btf_id);
+				if (sz < 0) {
+					pr_warn("global '%s': failed to resolve size of underlying type: %d\n",
+						name, (int)sz);
+					return -EINVAL;
+				}
+				dst_var->size = sz;
+				continue;
+			}
+
+			sec_vars = libbpf_reallocarray(sec_vars,
+						       dst_sec->sec_var_cnt + 1,
+						       sizeof(*dst_sec->sec_vars));
+			if (!sec_vars)
+				return -ENOMEM;
+
+			dst_sec->sec_vars = sec_vars;
+			dst_sec->sec_var_cnt++;
+
+			dst_var = &dst_sec->sec_vars[dst_sec->sec_var_cnt - 1];
+			dst_var->type = obj->btf_type_map[src_var->type];
+			dst_var->size = src_var->size;
+			dst_var->offset = src_sec->dst_off + src_var->offset;
+
+			if (glob_sym)
+				glob_sym->var_idx = dst_sec->sec_var_cnt - 1;
+		}
+	}
+
+	return 0;
+}
+
+static void *add_btf_ext_rec(struct btf_ext_sec_data *ext_data, const void *src_rec)
+{
+	void *tmp;
+
+	tmp = libbpf_reallocarray(ext_data->recs, ext_data->rec_cnt + 1, ext_data->rec_sz);
+	if (!tmp)
+		return NULL;
+	ext_data->recs = tmp;
+
+	tmp += ext_data->rec_cnt * ext_data->rec_sz;
+	memcpy(tmp, src_rec, ext_data->rec_sz);
+
+	ext_data->rec_cnt++;
+
+	return tmp;
+}
+
+static int linker_append_btf_ext(struct bpf_linker *linker, struct src_obj *obj)
+{
+	const struct btf_ext_info_sec *ext_sec;
+	const char *sec_name, *s;
+	struct src_sec *src_sec;
+	struct dst_sec *dst_sec;
+	int rec_sz, str_off, i;
+
+	if (!obj->btf_ext)
+		return 0;
+
+	rec_sz = obj->btf_ext->func_info.rec_size;
+	for_each_btf_ext_sec(&obj->btf_ext->func_info, ext_sec) {
+		struct bpf_func_info_min *src_rec, *dst_rec;
+
+		sec_name = btf__name_by_offset(obj->btf, ext_sec->sec_name_off);
+		src_sec = find_src_sec_by_name(obj, sec_name);
+		if (!src_sec) {
+			pr_warn("can't find section '%s' referenced from .BTF.ext\n", sec_name);
+			return -EINVAL;
+		}
+		dst_sec = &linker->secs[src_sec->dst_id];
+
+		if (dst_sec->func_info.rec_sz == 0)
+			dst_sec->func_info.rec_sz = rec_sz;
+		if (dst_sec->func_info.rec_sz != rec_sz) {
+			pr_warn("incompatible .BTF.ext record sizes for section '%s'\n", sec_name);
+			return -EINVAL;
+		}
+
+		for_each_btf_ext_rec(&obj->btf_ext->func_info, ext_sec, i, src_rec) {
+			dst_rec = add_btf_ext_rec(&dst_sec->func_info, src_rec);
+			if (!dst_rec)
+				return -ENOMEM;
+
+			dst_rec->insn_off += src_sec->dst_off;
+			dst_rec->type_id = obj->btf_type_map[dst_rec->type_id];
+		}
+	}
+
+	rec_sz = obj->btf_ext->line_info.rec_size;
+	for_each_btf_ext_sec(&obj->btf_ext->line_info, ext_sec) {
+		struct bpf_line_info_min *src_rec, *dst_rec;
+
+		sec_name = btf__name_by_offset(obj->btf, ext_sec->sec_name_off);
+		src_sec = find_src_sec_by_name(obj, sec_name);
+		if (!src_sec) {
+			pr_warn("can't find section '%s' referenced from .BTF.ext\n", sec_name);
+			return -EINVAL;
+		}
+		dst_sec = &linker->secs[src_sec->dst_id];
+
+		if (dst_sec->line_info.rec_sz == 0)
+			dst_sec->line_info.rec_sz = rec_sz;
+		if (dst_sec->line_info.rec_sz != rec_sz) {
+			pr_warn("incompatible .BTF.ext record sizes for section '%s'\n", sec_name);
+			return -EINVAL;
+		}
+
+		for_each_btf_ext_rec(&obj->btf_ext->line_info, ext_sec, i, src_rec) {
+			dst_rec = add_btf_ext_rec(&dst_sec->line_info, src_rec);
+			if (!dst_rec)
+				return -ENOMEM;
+
+			dst_rec->insn_off += src_sec->dst_off;
+
+			s = btf__str_by_offset(obj->btf, src_rec->file_name_off);
+			str_off = btf__add_str(linker->btf, s);
+			if (str_off < 0)
+				return -ENOMEM;
+			dst_rec->file_name_off = str_off;
+
+			s = btf__str_by_offset(obj->btf, src_rec->line_off);
+			str_off = btf__add_str(linker->btf, s);
+			if (str_off < 0)
+				return -ENOMEM;
+			dst_rec->line_off = str_off;
+
+			/* dst_rec->line_col is fine */
+		}
+	}
+
+	rec_sz = obj->btf_ext->core_relo_info.rec_size;
+	for_each_btf_ext_sec(&obj->btf_ext->core_relo_info, ext_sec) {
+		struct bpf_core_relo *src_rec, *dst_rec;
+
+		sec_name = btf__name_by_offset(obj->btf, ext_sec->sec_name_off);
+		src_sec = find_src_sec_by_name(obj, sec_name);
+		if (!src_sec) {
+			pr_warn("can't find section '%s' referenced from .BTF.ext\n", sec_name);
+			return -EINVAL;
+		}
+		dst_sec = &linker->secs[src_sec->dst_id];
+
+		if (dst_sec->core_relo_info.rec_sz == 0)
+			dst_sec->core_relo_info.rec_sz = rec_sz;
+		if (dst_sec->core_relo_info.rec_sz != rec_sz) {
+			pr_warn("incompatible .BTF.ext record sizes for section '%s'\n", sec_name);
+			return -EINVAL;
+		}
+
+		for_each_btf_ext_rec(&obj->btf_ext->core_relo_info, ext_sec, i, src_rec) {
+			dst_rec = add_btf_ext_rec(&dst_sec->core_relo_info, src_rec);
+			if (!dst_rec)
+				return -ENOMEM;
+
+			dst_rec->insn_off += src_sec->dst_off;
+			dst_rec->type_id = obj->btf_type_map[dst_rec->type_id];
+
+			s = btf__str_by_offset(obj->btf, src_rec->access_str_off);
+			str_off = btf__add_str(linker->btf, s);
+			if (str_off < 0)
+				return -ENOMEM;
+			dst_rec->access_str_off = str_off;
+
+			/* dst_rec->kind is fine */
+		}
+	}
+
+	return 0;
+}
+
+int bpf_linker__finalize(struct bpf_linker *linker)
+{
+	struct dst_sec *sec;
+	size_t strs_sz;
+	const void *strs;
+	int err, i;
+
+	if (!linker->elf)
+		return libbpf_err(-EINVAL);
+
+	err = finalize_btf(linker);
+	if (err)
+		return libbpf_err(err);
+
+	/* Finalize strings */
+	strs_sz = strset__data_size(linker->strtab_strs);
+	strs = strset__data(linker->strtab_strs);
+
+	sec = &linker->secs[linker->strtab_sec_idx];
+	sec->data->d_align = 1;
+	sec->data->d_off = 0LL;
+	sec->data->d_buf = (void *)strs;
+	sec->data->d_type = ELF_T_BYTE;
+	sec->data->d_size = strs_sz;
+	sec->shdr->sh_size = strs_sz;
+
+	for (i = 1; i < linker->sec_cnt; i++) {
+		sec = &linker->secs[i];
+
+		/* STRTAB is handled specially above */
+		if (sec->sec_idx == linker->strtab_sec_idx)
+			continue;
+
+		/* special ephemeral sections (.ksyms, .kconfig, etc) */
+		if (!sec->scn)
+			continue;
+
+		sec->data->d_buf = sec->raw_data;
+	}
+
+	/* Finalize ELF layout */
+	if (elf_update(linker->elf, ELF_C_NULL) < 0) {
+		err = -errno;
+		pr_warn_elf("failed to finalize ELF layout");
+		return libbpf_err(err);
+	}
+
+	/* Write out final ELF contents */
+	if (elf_update(linker->elf, ELF_C_WRITE) < 0) {
+		err = -errno;
+		pr_warn_elf("failed to write ELF contents");
+		return libbpf_err(err);
+	}
+
+	elf_end(linker->elf);
+	close(linker->fd);
+
+	linker->elf = NULL;
+	linker->fd = -1;
+
+	return 0;
+}
+
+static int emit_elf_data_sec(struct bpf_linker *linker, const char *sec_name,
+			     size_t align, const void *raw_data, size_t raw_sz)
+{
+	Elf_Scn *scn;
+	Elf_Data *data;
+	Elf64_Shdr *shdr;
+	int name_off;
+
+	name_off = strset__add_str(linker->strtab_strs, sec_name);
+	if (name_off < 0)
+		return name_off;
+
+	scn = elf_newscn(linker->elf);
+	if (!scn)
+		return -ENOMEM;
+	data = elf_newdata(scn);
+	if (!data)
+		return -ENOMEM;
+	shdr = elf64_getshdr(scn);
+	if (!shdr)
+		return -EINVAL;
+
+	shdr->sh_name = name_off;
+	shdr->sh_type = SHT_PROGBITS;
+	shdr->sh_flags = 0;
+	shdr->sh_size = raw_sz;
+	shdr->sh_link = 0;
+	shdr->sh_info = 0;
+	shdr->sh_addralign = align;
+	shdr->sh_entsize = 0;
+
+	data->d_type = ELF_T_BYTE;
+	data->d_size = raw_sz;
+	data->d_buf = (void *)raw_data;
+	data->d_align = align;
+	data->d_off = 0;
+
+	return 0;
+}
+
+static int finalize_btf(struct bpf_linker *linker)
+{
+	LIBBPF_OPTS(btf_dedup_opts, opts);
+	struct btf *btf = linker->btf;
+	const void *raw_data;
+	int i, j, id, err;
+	__u32 raw_sz;
+
+	/* bail out if no BTF data was produced */
+	if (btf__type_cnt(linker->btf) == 1)
+		return 0;
+
+	for (i = 1; i < linker->sec_cnt; i++) {
+		struct dst_sec *sec = &linker->secs[i];
+
+		if (!sec->has_btf)
+			continue;
+
+		id = btf__add_datasec(btf, sec->sec_name, sec->sec_sz);
+		if (id < 0) {
+			pr_warn("failed to add consolidated BTF type for datasec '%s': %d\n",
+				sec->sec_name, id);
+			return id;
+		}
+
+		for (j = 0; j < sec->sec_var_cnt; j++) {
+			struct btf_var_secinfo *vi = &sec->sec_vars[j];
+
+			if (btf__add_datasec_var_info(btf, vi->type, vi->offset, vi->size))
+				return -EINVAL;
+		}
+	}
+
+	err = finalize_btf_ext(linker);
+	if (err) {
+		pr_warn(".BTF.ext generation failed: %d\n", err);
+		return err;
+	}
+
+	opts.btf_ext = linker->btf_ext;
+	err = btf__dedup(linker->btf, &opts);
+	if (err) {
+		pr_warn("BTF dedup failed: %d\n", err);
+		return err;
+	}
+
+	/* Emit .BTF section */
+	raw_data = btf__raw_data(linker->btf, &raw_sz);
+	if (!raw_data)
+		return -ENOMEM;
+
+	err = emit_elf_data_sec(linker, BTF_ELF_SEC, 8, raw_data, raw_sz);
+	if (err) {
+		pr_warn("failed to write out .BTF ELF section: %d\n", err);
+		return err;
+	}
+
+	/* Emit .BTF.ext section */
+	if (linker->btf_ext) {
+		raw_data = btf_ext__get_raw_data(linker->btf_ext, &raw_sz);
+		if (!raw_data)
+			return -ENOMEM;
+
+		err = emit_elf_data_sec(linker, BTF_EXT_ELF_SEC, 8, raw_data, raw_sz);
+		if (err) {
+			pr_warn("failed to write out .BTF.ext ELF section: %d\n", err);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static int emit_btf_ext_data(struct bpf_linker *linker, void *output,
+			     const char *sec_name, struct btf_ext_sec_data *sec_data)
+{
+	struct btf_ext_info_sec *sec_info;
+	void *cur = output;
+	int str_off;
+	size_t sz;
+
+	if (!sec_data->rec_cnt)
+		return 0;
+
+	str_off = btf__add_str(linker->btf, sec_name);
+	if (str_off < 0)
+		return -ENOMEM;
+
+	sec_info = cur;
+	sec_info->sec_name_off = str_off;
+	sec_info->num_info = sec_data->rec_cnt;
+	cur += sizeof(struct btf_ext_info_sec);
+
+	sz = sec_data->rec_cnt * sec_data->rec_sz;
+	memcpy(cur, sec_data->recs, sz);
+	cur += sz;
+
+	return cur - output;
+}
+
+static int finalize_btf_ext(struct bpf_linker *linker)
+{
+	size_t funcs_sz = 0, lines_sz = 0, core_relos_sz = 0, total_sz = 0;
+	size_t func_rec_sz = 0, line_rec_sz = 0, core_relo_rec_sz = 0;
+	struct btf_ext_header *hdr;
+	void *data, *cur;
+	int i, err, sz;
+
+	/* validate that all sections have the same .BTF.ext record sizes
+	 * and calculate total data size for each type of data (func info,
+	 * line info, core relos)
+	 */
+	for (i = 1; i < linker->sec_cnt; i++) {
+		struct dst_sec *sec = &linker->secs[i];
+
+		if (sec->func_info.rec_cnt) {
+			if (func_rec_sz == 0)
+				func_rec_sz = sec->func_info.rec_sz;
+			if (func_rec_sz != sec->func_info.rec_sz) {
+				pr_warn("mismatch in func_info record size %zu != %u\n",
+					func_rec_sz, sec->func_info.rec_sz);
+				return -EINVAL;
+			}
+
+			funcs_sz += sizeof(struct btf_ext_info_sec) + func_rec_sz * sec->func_info.rec_cnt;
+		}
+		if (sec->line_info.rec_cnt) {
+			if (line_rec_sz == 0)
+				line_rec_sz = sec->line_info.rec_sz;
+			if (line_rec_sz != sec->line_info.rec_sz) {
+				pr_warn("mismatch in line_info record size %zu != %u\n",
+					line_rec_sz, sec->line_info.rec_sz);
+				return -EINVAL;
+			}
+
+			lines_sz += sizeof(struct btf_ext_info_sec) + line_rec_sz * sec->line_info.rec_cnt;
+		}
+		if (sec->core_relo_info.rec_cnt) {
+			if (core_relo_rec_sz == 0)
+				core_relo_rec_sz = sec->core_relo_info.rec_sz;
+			if (core_relo_rec_sz != sec->core_relo_info.rec_sz) {
+				pr_warn("mismatch in core_relo_info record size %zu != %u\n",
+					core_relo_rec_sz, sec->core_relo_info.rec_sz);
+				return -EINVAL;
+			}
+
+			core_relos_sz += sizeof(struct btf_ext_info_sec) + core_relo_rec_sz * sec->core_relo_info.rec_cnt;
+		}
+	}
+
+	if (!funcs_sz && !lines_sz && !core_relos_sz)
+		return 0;
+
+	total_sz += sizeof(struct btf_ext_header);
+	if (funcs_sz) {
+		funcs_sz += sizeof(__u32); /* record size prefix */
+		total_sz += funcs_sz;
+	}
+	if (lines_sz) {
+		lines_sz += sizeof(__u32); /* record size prefix */
+		total_sz += lines_sz;
+	}
+	if (core_relos_sz) {
+		core_relos_sz += sizeof(__u32); /* record size prefix */
+		total_sz += core_relos_sz;
+	}
+
+	cur = data = calloc(1, total_sz);
+	if (!data)
+		return -ENOMEM;
+
+	hdr = cur;
+	hdr->magic = BTF_MAGIC;
+	hdr->version = BTF_VERSION;
+	hdr->flags = 0;
+	hdr->hdr_len = sizeof(struct btf_ext_header);
+	cur += sizeof(struct btf_ext_header);
+
+	/* All offsets are in bytes relative to the end of this header */
+	hdr->func_info_off = 0;
+	hdr->func_info_len = funcs_sz;
+	hdr->line_info_off = funcs_sz;
+	hdr->line_info_len = lines_sz;
+	hdr->core_relo_off = funcs_sz + lines_sz;
+	hdr->core_relo_len = core_relos_sz;
+
+	if (funcs_sz) {
+		*(__u32 *)cur = func_rec_sz;
+		cur += sizeof(__u32);
+
+		for (i = 1; i < linker->sec_cnt; i++) {
+			struct dst_sec *sec = &linker->secs[i];
+
+			sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->func_info);
+			if (sz < 0) {
+				err = sz;
+				goto out;
+			}
+
+			cur += sz;
+		}
+	}
+
+	if (lines_sz) {
+		*(__u32 *)cur = line_rec_sz;
+		cur += sizeof(__u32);
+
+		for (i = 1; i < linker->sec_cnt; i++) {
+			struct dst_sec *sec = &linker->secs[i];
+
+			sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->line_info);
+			if (sz < 0) {
+				err = sz;
+				goto out;
+			}
+
+			cur += sz;
+		}
+	}
+
+	if (core_relos_sz) {
+		*(__u32 *)cur = core_relo_rec_sz;
+		cur += sizeof(__u32);
+
+		for (i = 1; i < linker->sec_cnt; i++) {
+			struct dst_sec *sec = &linker->secs[i];
+
+			sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->core_relo_info);
+			if (sz < 0) {
+				err = sz;
+				goto out;
+			}
+
+			cur += sz;
+		}
+	}
+
+	linker->btf_ext = btf_ext__new(data, total_sz);
+	err = libbpf_get_error(linker->btf_ext);
+	if (err) {
+		linker->btf_ext = NULL;
+		pr_warn("failed to parse final .BTF.ext data: %d\n", err);
+		goto out;
+	}
+
+out:
+	free(data);
+	return err;
+}
diff --git a/src/netlink.c b/src/netlink.c
new file mode 100644
index 0000000..3510458
--- /dev/null
+++ b/src/netlink.c
@@ -0,0 +1,813 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2018 Facebook */
+
+#include <stdlib.h>
+#include <memory.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <linux/bpf.h>
+#include <linux/if_ether.h>
+#include <linux/pkt_cls.h>
+#include <linux/rtnetlink.h>
+#include <sys/socket.h>
+#include <errno.h>
+#include <time.h>
+
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+#include "nlattr.h"
+
+#ifndef SOL_NETLINK
+#define SOL_NETLINK 270
+#endif
+
+typedef int (*libbpf_dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);
+
+typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, libbpf_dump_nlmsg_t,
+			      void *cookie);
+
+struct xdp_link_info {
+	__u32 prog_id;
+	__u32 drv_prog_id;
+	__u32 hw_prog_id;
+	__u32 skb_prog_id;
+	__u8 attach_mode;
+};
+
+struct xdp_id_md {
+	int ifindex;
+	__u32 flags;
+	struct xdp_link_info info;
+};
+
+static int libbpf_netlink_open(__u32 *nl_pid)
+{
+	struct sockaddr_nl sa;
+	socklen_t addrlen;
+	int one = 1, ret;
+	int sock;
+
+	memset(&sa, 0, sizeof(sa));
+	sa.nl_family = AF_NETLINK;
+
+	sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
+	if (sock < 0)
+		return -errno;
+
+	if (setsockopt(sock, SOL_NETLINK, NETLINK_EXT_ACK,
+		       &one, sizeof(one)) < 0) {
+		pr_warn("Netlink error reporting not supported\n");
+	}
+
+	if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
+		ret = -errno;
+		goto cleanup;
+	}
+
+	addrlen = sizeof(sa);
+	if (getsockname(sock, (struct sockaddr *)&sa, &addrlen) < 0) {
+		ret = -errno;
+		goto cleanup;
+	}
+
+	if (addrlen != sizeof(sa)) {
+		ret = -LIBBPF_ERRNO__INTERNAL;
+		goto cleanup;
+	}
+
+	*nl_pid = sa.nl_pid;
+	return sock;
+
+cleanup:
+	close(sock);
+	return ret;
+}
+
+static void libbpf_netlink_close(int sock)
+{
+	close(sock);
+}
+
+enum {
+	NL_CONT,
+	NL_NEXT,
+	NL_DONE,
+};
+
+static int netlink_recvmsg(int sock, struct msghdr *mhdr, int flags)
+{
+	int len;
+
+	do {
+		len = recvmsg(sock, mhdr, flags);
+	} while (len < 0 && (errno == EINTR || errno == EAGAIN));
+
+	if (len < 0)
+		return -errno;
+	return len;
+}
+
+static int alloc_iov(struct iovec *iov, int len)
+{
+	void *nbuf;
+
+	nbuf = realloc(iov->iov_base, len);
+	if (!nbuf)
+		return -ENOMEM;
+
+	iov->iov_base = nbuf;
+	iov->iov_len = len;
+	return 0;
+}
+
+static int libbpf_netlink_recv(int sock, __u32 nl_pid, int seq,
+			       __dump_nlmsg_t _fn, libbpf_dump_nlmsg_t fn,
+			       void *cookie)
+{
+	struct iovec iov = {};
+	struct msghdr mhdr = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+	bool multipart = true;
+	struct nlmsgerr *err;
+	struct nlmsghdr *nh;
+	int len, ret;
+
+	ret = alloc_iov(&iov, 4096);
+	if (ret)
+		goto done;
+
+	while (multipart) {
+start:
+		multipart = false;
+		len = netlink_recvmsg(sock, &mhdr, MSG_PEEK | MSG_TRUNC);
+		if (len < 0) {
+			ret = len;
+			goto done;
+		}
+
+		if (len > iov.iov_len) {
+			ret = alloc_iov(&iov, len);
+			if (ret)
+				goto done;
+		}
+
+		len = netlink_recvmsg(sock, &mhdr, 0);
+		if (len < 0) {
+			ret = len;
+			goto done;
+		}
+
+		if (len == 0)
+			break;
+
+		for (nh = (struct nlmsghdr *)iov.iov_base; NLMSG_OK(nh, len);
+		     nh = NLMSG_NEXT(nh, len)) {
+			if (nh->nlmsg_pid != nl_pid) {
+				ret = -LIBBPF_ERRNO__WRNGPID;
+				goto done;
+			}
+			if (nh->nlmsg_seq != seq) {
+				ret = -LIBBPF_ERRNO__INVSEQ;
+				goto done;
+			}
+			if (nh->nlmsg_flags & NLM_F_MULTI)
+				multipart = true;
+			switch (nh->nlmsg_type) {
+			case NLMSG_ERROR:
+				err = (struct nlmsgerr *)NLMSG_DATA(nh);
+				if (!err->error)
+					continue;
+				ret = err->error;
+				libbpf_nla_dump_errormsg(nh);
+				goto done;
+			case NLMSG_DONE:
+				ret = 0;
+				goto done;
+			default:
+				break;
+			}
+			if (_fn) {
+				ret = _fn(nh, fn, cookie);
+				switch (ret) {
+				case NL_CONT:
+					break;
+				case NL_NEXT:
+					goto start;
+				case NL_DONE:
+					ret = 0;
+					goto done;
+				default:
+					goto done;
+				}
+			}
+		}
+	}
+	ret = 0;
+done:
+	free(iov.iov_base);
+	return ret;
+}
+
+static int libbpf_netlink_send_recv(struct libbpf_nla_req *req,
+				    __dump_nlmsg_t parse_msg,
+				    libbpf_dump_nlmsg_t parse_attr,
+				    void *cookie)
+{
+	__u32 nl_pid = 0;
+	int sock, ret;
+
+	sock = libbpf_netlink_open(&nl_pid);
+	if (sock < 0)
+		return sock;
+
+	req->nh.nlmsg_pid = 0;
+	req->nh.nlmsg_seq = time(NULL);
+
+	if (send(sock, req, req->nh.nlmsg_len, 0) < 0) {
+		ret = -errno;
+		goto out;
+	}
+
+	ret = libbpf_netlink_recv(sock, nl_pid, req->nh.nlmsg_seq,
+				  parse_msg, parse_attr, cookie);
+out:
+	libbpf_netlink_close(sock);
+	return ret;
+}
+
+static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd,
+					 __u32 flags)
+{
+	struct nlattr *nla;
+	int ret;
+	struct libbpf_nla_req req;
+
+	memset(&req, 0, sizeof(req));
+	req.nh.nlmsg_len      = NLMSG_LENGTH(sizeof(struct ifinfomsg));
+	req.nh.nlmsg_flags    = NLM_F_REQUEST | NLM_F_ACK;
+	req.nh.nlmsg_type     = RTM_SETLINK;
+	req.ifinfo.ifi_family = AF_UNSPEC;
+	req.ifinfo.ifi_index  = ifindex;
+
+	nla = nlattr_begin_nested(&req, IFLA_XDP);
+	if (!nla)
+		return -EMSGSIZE;
+	ret = nlattr_add(&req, IFLA_XDP_FD, &fd, sizeof(fd));
+	if (ret < 0)
+		return ret;
+	if (flags) {
+		ret = nlattr_add(&req, IFLA_XDP_FLAGS, &flags, sizeof(flags));
+		if (ret < 0)
+			return ret;
+	}
+	if (flags & XDP_FLAGS_REPLACE) {
+		ret = nlattr_add(&req, IFLA_XDP_EXPECTED_FD, &old_fd,
+				 sizeof(old_fd));
+		if (ret < 0)
+			return ret;
+	}
+	nlattr_end_nested(&req, nla);
+
+	return libbpf_netlink_send_recv(&req, NULL, NULL, NULL);
+}
+
+int bpf_xdp_attach(int ifindex, int prog_fd, __u32 flags, const struct bpf_xdp_attach_opts *opts)
+{
+	int old_prog_fd, err;
+
+	if (!OPTS_VALID(opts, bpf_xdp_attach_opts))
+		return libbpf_err(-EINVAL);
+
+	old_prog_fd = OPTS_GET(opts, old_prog_fd, 0);
+	if (old_prog_fd)
+		flags |= XDP_FLAGS_REPLACE;
+	else
+		old_prog_fd = -1;
+
+	err = __bpf_set_link_xdp_fd_replace(ifindex, prog_fd, old_prog_fd, flags);
+	return libbpf_err(err);
+}
+
+int bpf_xdp_detach(int ifindex, __u32 flags, const struct bpf_xdp_attach_opts *opts)
+{
+	return bpf_xdp_attach(ifindex, -1, flags, opts);
+}
+
+static int __dump_link_nlmsg(struct nlmsghdr *nlh,
+			     libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie)
+{
+	struct nlattr *tb[IFLA_MAX + 1], *attr;
+	struct ifinfomsg *ifi = NLMSG_DATA(nlh);
+	int len;
+
+	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*ifi));
+	attr = (struct nlattr *) ((void *) ifi + NLMSG_ALIGN(sizeof(*ifi)));
+
+	if (libbpf_nla_parse(tb, IFLA_MAX, attr, len, NULL) != 0)
+		return -LIBBPF_ERRNO__NLPARSE;
+
+	return dump_link_nlmsg(cookie, ifi, tb);
+}
+
+static int get_xdp_info(void *cookie, void *msg, struct nlattr **tb)
+{
+	struct nlattr *xdp_tb[IFLA_XDP_MAX + 1];
+	struct xdp_id_md *xdp_id = cookie;
+	struct ifinfomsg *ifinfo = msg;
+	int ret;
+
+	if (xdp_id->ifindex && xdp_id->ifindex != ifinfo->ifi_index)
+		return 0;
+
+	if (!tb[IFLA_XDP])
+		return 0;
+
+	ret = libbpf_nla_parse_nested(xdp_tb, IFLA_XDP_MAX, tb[IFLA_XDP], NULL);
+	if (ret)
+		return ret;
+
+	if (!xdp_tb[IFLA_XDP_ATTACHED])
+		return 0;
+
+	xdp_id->info.attach_mode = libbpf_nla_getattr_u8(
+		xdp_tb[IFLA_XDP_ATTACHED]);
+
+	if (xdp_id->info.attach_mode == XDP_ATTACHED_NONE)
+		return 0;
+
+	if (xdp_tb[IFLA_XDP_PROG_ID])
+		xdp_id->info.prog_id = libbpf_nla_getattr_u32(
+			xdp_tb[IFLA_XDP_PROG_ID]);
+
+	if (xdp_tb[IFLA_XDP_SKB_PROG_ID])
+		xdp_id->info.skb_prog_id = libbpf_nla_getattr_u32(
+			xdp_tb[IFLA_XDP_SKB_PROG_ID]);
+
+	if (xdp_tb[IFLA_XDP_DRV_PROG_ID])
+		xdp_id->info.drv_prog_id = libbpf_nla_getattr_u32(
+			xdp_tb[IFLA_XDP_DRV_PROG_ID]);
+
+	if (xdp_tb[IFLA_XDP_HW_PROG_ID])
+		xdp_id->info.hw_prog_id = libbpf_nla_getattr_u32(
+			xdp_tb[IFLA_XDP_HW_PROG_ID]);
+
+	return 0;
+}
+
+int bpf_xdp_query(int ifindex, int xdp_flags, struct bpf_xdp_query_opts *opts)
+{
+	struct libbpf_nla_req req = {
+		.nh.nlmsg_len      = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
+		.nh.nlmsg_type     = RTM_GETLINK,
+		.nh.nlmsg_flags    = NLM_F_DUMP | NLM_F_REQUEST,
+		.ifinfo.ifi_family = AF_PACKET,
+	};
+	struct xdp_id_md xdp_id = {};
+	int err;
+
+	if (!OPTS_VALID(opts, bpf_xdp_query_opts))
+		return libbpf_err(-EINVAL);
+
+	if (xdp_flags & ~XDP_FLAGS_MASK)
+		return libbpf_err(-EINVAL);
+
+	/* Check whether the single {HW,DRV,SKB} mode is set */
+	xdp_flags &= XDP_FLAGS_SKB_MODE | XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE;
+	if (xdp_flags & (xdp_flags - 1))
+		return libbpf_err(-EINVAL);
+
+	xdp_id.ifindex = ifindex;
+	xdp_id.flags = xdp_flags;
+
+	err = libbpf_netlink_send_recv(&req, __dump_link_nlmsg,
+				       get_xdp_info, &xdp_id);
+	if (err)
+		return libbpf_err(err);
+
+	OPTS_SET(opts, prog_id, xdp_id.info.prog_id);
+	OPTS_SET(opts, drv_prog_id, xdp_id.info.drv_prog_id);
+	OPTS_SET(opts, hw_prog_id, xdp_id.info.hw_prog_id);
+	OPTS_SET(opts, skb_prog_id, xdp_id.info.skb_prog_id);
+	OPTS_SET(opts, attach_mode, xdp_id.info.attach_mode);
+
+	return 0;
+}
+
+int bpf_xdp_query_id(int ifindex, int flags, __u32 *prog_id)
+{
+	LIBBPF_OPTS(bpf_xdp_query_opts, opts);
+	int ret;
+
+	ret = bpf_xdp_query(ifindex, flags, &opts);
+	if (ret)
+		return libbpf_err(ret);
+
+	flags &= XDP_FLAGS_MODES;
+
+	if (opts.attach_mode != XDP_ATTACHED_MULTI && !flags)
+		*prog_id = opts.prog_id;
+	else if (flags & XDP_FLAGS_DRV_MODE)
+		*prog_id = opts.drv_prog_id;
+	else if (flags & XDP_FLAGS_HW_MODE)
+		*prog_id = opts.hw_prog_id;
+	else if (flags & XDP_FLAGS_SKB_MODE)
+		*prog_id = opts.skb_prog_id;
+	else
+		*prog_id = 0;
+
+	return 0;
+}
+
+
+typedef int (*qdisc_config_t)(struct libbpf_nla_req *req);
+
+static int clsact_config(struct libbpf_nla_req *req)
+{
+	req->tc.tcm_parent = TC_H_CLSACT;
+	req->tc.tcm_handle = TC_H_MAKE(TC_H_CLSACT, 0);
+
+	return nlattr_add(req, TCA_KIND, "clsact", sizeof("clsact"));
+}
+
+static int attach_point_to_config(struct bpf_tc_hook *hook,
+				  qdisc_config_t *config)
+{
+	switch (OPTS_GET(hook, attach_point, 0)) {
+	case BPF_TC_INGRESS:
+	case BPF_TC_EGRESS:
+	case BPF_TC_INGRESS | BPF_TC_EGRESS:
+		if (OPTS_GET(hook, parent, 0))
+			return -EINVAL;
+		*config = &clsact_config;
+		return 0;
+	case BPF_TC_CUSTOM:
+		return -EOPNOTSUPP;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int tc_get_tcm_parent(enum bpf_tc_attach_point attach_point,
+			     __u32 *parent)
+{
+	switch (attach_point) {
+	case BPF_TC_INGRESS:
+	case BPF_TC_EGRESS:
+		if (*parent)
+			return -EINVAL;
+		*parent = TC_H_MAKE(TC_H_CLSACT,
+				    attach_point == BPF_TC_INGRESS ?
+				    TC_H_MIN_INGRESS : TC_H_MIN_EGRESS);
+		break;
+	case BPF_TC_CUSTOM:
+		if (!*parent)
+			return -EINVAL;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int tc_qdisc_modify(struct bpf_tc_hook *hook, int cmd, int flags)
+{
+	qdisc_config_t config;
+	int ret;
+	struct libbpf_nla_req req;
+
+	ret = attach_point_to_config(hook, &config);
+	if (ret < 0)
+		return ret;
+
+	memset(&req, 0, sizeof(req));
+	req.nh.nlmsg_len   = NLMSG_LENGTH(sizeof(struct tcmsg));
+	req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | flags;
+	req.nh.nlmsg_type  = cmd;
+	req.tc.tcm_family  = AF_UNSPEC;
+	req.tc.tcm_ifindex = OPTS_GET(hook, ifindex, 0);
+
+	ret = config(&req);
+	if (ret < 0)
+		return ret;
+
+	return libbpf_netlink_send_recv(&req, NULL, NULL, NULL);
+}
+
+static int tc_qdisc_create_excl(struct bpf_tc_hook *hook)
+{
+	return tc_qdisc_modify(hook, RTM_NEWQDISC, NLM_F_CREATE | NLM_F_EXCL);
+}
+
+static int tc_qdisc_delete(struct bpf_tc_hook *hook)
+{
+	return tc_qdisc_modify(hook, RTM_DELQDISC, 0);
+}
+
+int bpf_tc_hook_create(struct bpf_tc_hook *hook)
+{
+	int ret;
+
+	if (!hook || !OPTS_VALID(hook, bpf_tc_hook) ||
+	    OPTS_GET(hook, ifindex, 0) <= 0)
+		return libbpf_err(-EINVAL);
+
+	ret = tc_qdisc_create_excl(hook);
+	return libbpf_err(ret);
+}
+
+static int __bpf_tc_detach(const struct bpf_tc_hook *hook,
+			   const struct bpf_tc_opts *opts,
+			   const bool flush);
+
+int bpf_tc_hook_destroy(struct bpf_tc_hook *hook)
+{
+	if (!hook || !OPTS_VALID(hook, bpf_tc_hook) ||
+	    OPTS_GET(hook, ifindex, 0) <= 0)
+		return libbpf_err(-EINVAL);
+
+	switch (OPTS_GET(hook, attach_point, 0)) {
+	case BPF_TC_INGRESS:
+	case BPF_TC_EGRESS:
+		return libbpf_err(__bpf_tc_detach(hook, NULL, true));
+	case BPF_TC_INGRESS | BPF_TC_EGRESS:
+		return libbpf_err(tc_qdisc_delete(hook));
+	case BPF_TC_CUSTOM:
+		return libbpf_err(-EOPNOTSUPP);
+	default:
+		return libbpf_err(-EINVAL);
+	}
+}
+
+struct bpf_cb_ctx {
+	struct bpf_tc_opts *opts;
+	bool processed;
+};
+
+static int __get_tc_info(void *cookie, struct tcmsg *tc, struct nlattr **tb,
+			 bool unicast)
+{
+	struct nlattr *tbb[TCA_BPF_MAX + 1];
+	struct bpf_cb_ctx *info = cookie;
+
+	if (!info || !info->opts)
+		return -EINVAL;
+	if (unicast && info->processed)
+		return -EINVAL;
+	if (!tb[TCA_OPTIONS])
+		return NL_CONT;
+
+	libbpf_nla_parse_nested(tbb, TCA_BPF_MAX, tb[TCA_OPTIONS], NULL);
+	if (!tbb[TCA_BPF_ID])
+		return -EINVAL;
+
+	OPTS_SET(info->opts, prog_id, libbpf_nla_getattr_u32(tbb[TCA_BPF_ID]));
+	OPTS_SET(info->opts, handle, tc->tcm_handle);
+	OPTS_SET(info->opts, priority, TC_H_MAJ(tc->tcm_info) >> 16);
+
+	info->processed = true;
+	return unicast ? NL_NEXT : NL_DONE;
+}
+
+static int get_tc_info(struct nlmsghdr *nh, libbpf_dump_nlmsg_t fn,
+		       void *cookie)
+{
+	struct tcmsg *tc = NLMSG_DATA(nh);
+	struct nlattr *tb[TCA_MAX + 1];
+
+	libbpf_nla_parse(tb, TCA_MAX,
+			 (struct nlattr *)((void *)tc + NLMSG_ALIGN(sizeof(*tc))),
+			 NLMSG_PAYLOAD(nh, sizeof(*tc)), NULL);
+	if (!tb[TCA_KIND])
+		return NL_CONT;
+	return __get_tc_info(cookie, tc, tb, nh->nlmsg_flags & NLM_F_ECHO);
+}
+
+static int tc_add_fd_and_name(struct libbpf_nla_req *req, int fd)
+{
+	struct bpf_prog_info info;
+	__u32 info_len = sizeof(info);
+	char name[256];
+	int len, ret;
+
+	memset(&info, 0, info_len);
+	ret = bpf_obj_get_info_by_fd(fd, &info, &info_len);
+	if (ret < 0)
+		return ret;
+
+	ret = nlattr_add(req, TCA_BPF_FD, &fd, sizeof(fd));
+	if (ret < 0)
+		return ret;
+	len = snprintf(name, sizeof(name), "%s:[%u]", info.name, info.id);
+	if (len < 0)
+		return -errno;
+	if (len >= sizeof(name))
+		return -ENAMETOOLONG;
+	return nlattr_add(req, TCA_BPF_NAME, name, len + 1);
+}
+
+int bpf_tc_attach(const struct bpf_tc_hook *hook, struct bpf_tc_opts *opts)
+{
+	__u32 protocol, bpf_flags, handle, priority, parent, prog_id, flags;
+	int ret, ifindex, attach_point, prog_fd;
+	struct bpf_cb_ctx info = {};
+	struct libbpf_nla_req req;
+	struct nlattr *nla;
+
+	if (!hook || !opts ||
+	    !OPTS_VALID(hook, bpf_tc_hook) ||
+	    !OPTS_VALID(opts, bpf_tc_opts))
+		return libbpf_err(-EINVAL);
+
+	ifindex      = OPTS_GET(hook, ifindex, 0);
+	parent       = OPTS_GET(hook, parent, 0);
+	attach_point = OPTS_GET(hook, attach_point, 0);
+
+	handle       = OPTS_GET(opts, handle, 0);
+	priority     = OPTS_GET(opts, priority, 0);
+	prog_fd      = OPTS_GET(opts, prog_fd, 0);
+	prog_id      = OPTS_GET(opts, prog_id, 0);
+	flags        = OPTS_GET(opts, flags, 0);
+
+	if (ifindex <= 0 || !prog_fd || prog_id)
+		return libbpf_err(-EINVAL);
+	if (priority > UINT16_MAX)
+		return libbpf_err(-EINVAL);
+	if (flags & ~BPF_TC_F_REPLACE)
+		return libbpf_err(-EINVAL);
+
+	flags = (flags & BPF_TC_F_REPLACE) ? NLM_F_REPLACE : NLM_F_EXCL;
+	protocol = ETH_P_ALL;
+
+	memset(&req, 0, sizeof(req));
+	req.nh.nlmsg_len   = NLMSG_LENGTH(sizeof(struct tcmsg));
+	req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | NLM_F_CREATE |
+			     NLM_F_ECHO | flags;
+	req.nh.nlmsg_type  = RTM_NEWTFILTER;
+	req.tc.tcm_family  = AF_UNSPEC;
+	req.tc.tcm_ifindex = ifindex;
+	req.tc.tcm_handle  = handle;
+	req.tc.tcm_info    = TC_H_MAKE(priority << 16, htons(protocol));
+
+	ret = tc_get_tcm_parent(attach_point, &parent);
+	if (ret < 0)
+		return libbpf_err(ret);
+	req.tc.tcm_parent = parent;
+
+	ret = nlattr_add(&req, TCA_KIND, "bpf", sizeof("bpf"));
+	if (ret < 0)
+		return libbpf_err(ret);
+	nla = nlattr_begin_nested(&req, TCA_OPTIONS);
+	if (!nla)
+		return libbpf_err(-EMSGSIZE);
+	ret = tc_add_fd_and_name(&req, prog_fd);
+	if (ret < 0)
+		return libbpf_err(ret);
+	bpf_flags = TCA_BPF_FLAG_ACT_DIRECT;
+	ret = nlattr_add(&req, TCA_BPF_FLAGS, &bpf_flags, sizeof(bpf_flags));
+	if (ret < 0)
+		return libbpf_err(ret);
+	nlattr_end_nested(&req, nla);
+
+	info.opts = opts;
+
+	ret = libbpf_netlink_send_recv(&req, get_tc_info, NULL, &info);
+	if (ret < 0)
+		return libbpf_err(ret);
+	if (!info.processed)
+		return libbpf_err(-ENOENT);
+	return ret;
+}
+
+static int __bpf_tc_detach(const struct bpf_tc_hook *hook,
+			   const struct bpf_tc_opts *opts,
+			   const bool flush)
+{
+	__u32 protocol = 0, handle, priority, parent, prog_id, flags;
+	int ret, ifindex, attach_point, prog_fd;
+	struct libbpf_nla_req req;
+
+	if (!hook ||
+	    !OPTS_VALID(hook, bpf_tc_hook) ||
+	    !OPTS_VALID(opts, bpf_tc_opts))
+		return -EINVAL;
+
+	ifindex      = OPTS_GET(hook, ifindex, 0);
+	parent       = OPTS_GET(hook, parent, 0);
+	attach_point = OPTS_GET(hook, attach_point, 0);
+
+	handle       = OPTS_GET(opts, handle, 0);
+	priority     = OPTS_GET(opts, priority, 0);
+	prog_fd      = OPTS_GET(opts, prog_fd, 0);
+	prog_id      = OPTS_GET(opts, prog_id, 0);
+	flags        = OPTS_GET(opts, flags, 0);
+
+	if (ifindex <= 0 || flags || prog_fd || prog_id)
+		return -EINVAL;
+	if (priority > UINT16_MAX)
+		return -EINVAL;
+	if (!flush) {
+		if (!handle || !priority)
+			return -EINVAL;
+		protocol = ETH_P_ALL;
+	} else {
+		if (handle || priority)
+			return -EINVAL;
+	}
+
+	memset(&req, 0, sizeof(req));
+	req.nh.nlmsg_len   = NLMSG_LENGTH(sizeof(struct tcmsg));
+	req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
+	req.nh.nlmsg_type  = RTM_DELTFILTER;
+	req.tc.tcm_family  = AF_UNSPEC;
+	req.tc.tcm_ifindex = ifindex;
+	if (!flush) {
+		req.tc.tcm_handle = handle;
+		req.tc.tcm_info   = TC_H_MAKE(priority << 16, htons(protocol));
+	}
+
+	ret = tc_get_tcm_parent(attach_point, &parent);
+	if (ret < 0)
+		return ret;
+	req.tc.tcm_parent = parent;
+
+	if (!flush) {
+		ret = nlattr_add(&req, TCA_KIND, "bpf", sizeof("bpf"));
+		if (ret < 0)
+			return ret;
+	}
+
+	return libbpf_netlink_send_recv(&req, NULL, NULL, NULL);
+}
+
+int bpf_tc_detach(const struct bpf_tc_hook *hook,
+		  const struct bpf_tc_opts *opts)
+{
+	int ret;
+
+	if (!opts)
+		return libbpf_err(-EINVAL);
+
+	ret = __bpf_tc_detach(hook, opts, false);
+	return libbpf_err(ret);
+}
+
+int bpf_tc_query(const struct bpf_tc_hook *hook, struct bpf_tc_opts *opts)
+{
+	__u32 protocol, handle, priority, parent, prog_id, flags;
+	int ret, ifindex, attach_point, prog_fd;
+	struct bpf_cb_ctx info = {};
+	struct libbpf_nla_req req;
+
+	if (!hook || !opts ||
+	    !OPTS_VALID(hook, bpf_tc_hook) ||
+	    !OPTS_VALID(opts, bpf_tc_opts))
+		return libbpf_err(-EINVAL);
+
+	ifindex      = OPTS_GET(hook, ifindex, 0);
+	parent       = OPTS_GET(hook, parent, 0);
+	attach_point = OPTS_GET(hook, attach_point, 0);
+
+	handle       = OPTS_GET(opts, handle, 0);
+	priority     = OPTS_GET(opts, priority, 0);
+	prog_fd      = OPTS_GET(opts, prog_fd, 0);
+	prog_id      = OPTS_GET(opts, prog_id, 0);
+	flags        = OPTS_GET(opts, flags, 0);
+
+	if (ifindex <= 0 || flags || prog_fd || prog_id ||
+	    !handle || !priority)
+		return libbpf_err(-EINVAL);
+	if (priority > UINT16_MAX)
+		return libbpf_err(-EINVAL);
+
+	protocol = ETH_P_ALL;
+
+	memset(&req, 0, sizeof(req));
+	req.nh.nlmsg_len   = NLMSG_LENGTH(sizeof(struct tcmsg));
+	req.nh.nlmsg_flags = NLM_F_REQUEST;
+	req.nh.nlmsg_type  = RTM_GETTFILTER;
+	req.tc.tcm_family  = AF_UNSPEC;
+	req.tc.tcm_ifindex = ifindex;
+	req.tc.tcm_handle  = handle;
+	req.tc.tcm_info    = TC_H_MAKE(priority << 16, htons(protocol));
+
+	ret = tc_get_tcm_parent(attach_point, &parent);
+	if (ret < 0)
+		return libbpf_err(ret);
+	req.tc.tcm_parent = parent;
+
+	ret = nlattr_add(&req, TCA_KIND, "bpf", sizeof("bpf"));
+	if (ret < 0)
+		return libbpf_err(ret);
+
+	info.opts = opts;
+
+	ret = libbpf_netlink_send_recv(&req, get_tc_info, NULL, &info);
+	if (ret < 0)
+		return libbpf_err(ret);
+	if (!info.processed)
+		return libbpf_err(-ENOENT);
+	return ret;
+}
diff --git a/src/nlattr.c b/src/nlattr.c
new file mode 100644
index 0000000..3900d05
--- /dev/null
+++ b/src/nlattr.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * NETLINK      Netlink attributes
+ *
+ * Copyright (c) 2003-2013 Thomas Graf <tgraf@suug.ch>
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+#include <linux/rtnetlink.h>
+#include "nlattr.h"
+#include "libbpf_internal.h"
+
+static uint16_t nla_attr_minlen[LIBBPF_NLA_TYPE_MAX+1] = {
+	[LIBBPF_NLA_U8]		= sizeof(uint8_t),
+	[LIBBPF_NLA_U16]	= sizeof(uint16_t),
+	[LIBBPF_NLA_U32]	= sizeof(uint32_t),
+	[LIBBPF_NLA_U64]	= sizeof(uint64_t),
+	[LIBBPF_NLA_STRING]	= 1,
+	[LIBBPF_NLA_FLAG]	= 0,
+};
+
+static struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
+{
+	int totlen = NLA_ALIGN(nla->nla_len);
+
+	*remaining -= totlen;
+	return (struct nlattr *)((void *)nla + totlen);
+}
+
+static int nla_ok(const struct nlattr *nla, int remaining)
+{
+	return remaining >= (int)sizeof(*nla) &&
+	       nla->nla_len >= sizeof(*nla) &&
+	       nla->nla_len <= remaining;
+}
+
+static int nla_type(const struct nlattr *nla)
+{
+	return nla->nla_type & NLA_TYPE_MASK;
+}
+
+static int validate_nla(struct nlattr *nla, int maxtype,
+			struct libbpf_nla_policy *policy)
+{
+	struct libbpf_nla_policy *pt;
+	unsigned int minlen = 0;
+	int type = nla_type(nla);
+
+	if (type < 0 || type > maxtype)
+		return 0;
+
+	pt = &policy[type];
+
+	if (pt->type > LIBBPF_NLA_TYPE_MAX)
+		return 0;
+
+	if (pt->minlen)
+		minlen = pt->minlen;
+	else if (pt->type != LIBBPF_NLA_UNSPEC)
+		minlen = nla_attr_minlen[pt->type];
+
+	if (libbpf_nla_len(nla) < minlen)
+		return -1;
+
+	if (pt->maxlen && libbpf_nla_len(nla) > pt->maxlen)
+		return -1;
+
+	if (pt->type == LIBBPF_NLA_STRING) {
+		char *data = libbpf_nla_data(nla);
+
+		if (data[libbpf_nla_len(nla) - 1] != '\0')
+			return -1;
+	}
+
+	return 0;
+}
+
+static inline int nlmsg_len(const struct nlmsghdr *nlh)
+{
+	return nlh->nlmsg_len - NLMSG_HDRLEN;
+}
+
+/**
+ * Create attribute index based on a stream of attributes.
+ * @arg tb		Index array to be filled (maxtype+1 elements).
+ * @arg maxtype		Maximum attribute type expected and accepted.
+ * @arg head		Head of attribute stream.
+ * @arg len		Length of attribute stream.
+ * @arg policy		Attribute validation policy.
+ *
+ * Iterates over the stream of attributes and stores a pointer to each
+ * attribute in the index array using the attribute type as index to
+ * the array. Attribute with a type greater than the maximum type
+ * specified will be silently ignored in order to maintain backwards
+ * compatibility. If \a policy is not NULL, the attribute will be
+ * validated using the specified policy.
+ *
+ * @see nla_validate
+ * @return 0 on success or a negative error code.
+ */
+int libbpf_nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head,
+		     int len, struct libbpf_nla_policy *policy)
+{
+	struct nlattr *nla;
+	int rem, err;
+
+	memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
+
+	libbpf_nla_for_each_attr(nla, head, len, rem) {
+		int type = nla_type(nla);
+
+		if (type > maxtype)
+			continue;
+
+		if (policy) {
+			err = validate_nla(nla, maxtype, policy);
+			if (err < 0)
+				goto errout;
+		}
+
+		if (tb[type])
+			pr_warn("Attribute of type %#x found multiple times in message, "
+				"previous attribute is being ignored.\n", type);
+
+		tb[type] = nla;
+	}
+
+	err = 0;
+errout:
+	return err;
+}
+
+/**
+ * Create attribute index based on nested attribute
+ * @arg tb              Index array to be filled (maxtype+1 elements).
+ * @arg maxtype         Maximum attribute type expected and accepted.
+ * @arg nla             Nested Attribute.
+ * @arg policy          Attribute validation policy.
+ *
+ * Feeds the stream of attributes nested into the specified attribute
+ * to libbpf_nla_parse().
+ *
+ * @see libbpf_nla_parse
+ * @return 0 on success or a negative error code.
+ */
+int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype,
+			    struct nlattr *nla,
+			    struct libbpf_nla_policy *policy)
+{
+	return libbpf_nla_parse(tb, maxtype, libbpf_nla_data(nla),
+				libbpf_nla_len(nla), policy);
+}
+
+/* dump netlink extended ack error message */
+int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh)
+{
+	struct libbpf_nla_policy extack_policy[NLMSGERR_ATTR_MAX + 1] = {
+		[NLMSGERR_ATTR_MSG]	= { .type = LIBBPF_NLA_STRING },
+		[NLMSGERR_ATTR_OFFS]	= { .type = LIBBPF_NLA_U32 },
+	};
+	struct nlattr *tb[NLMSGERR_ATTR_MAX + 1], *attr;
+	struct nlmsgerr *err;
+	char *errmsg = NULL;
+	int hlen, alen;
+
+	/* no TLVs, nothing to do here */
+	if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS))
+		return 0;
+
+	err = (struct nlmsgerr *)NLMSG_DATA(nlh);
+	hlen = sizeof(*err);
+
+	/* if NLM_F_CAPPED is set then the inner err msg was capped */
+	if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
+		hlen += nlmsg_len(&err->msg);
+
+	attr = (struct nlattr *) ((void *) err + hlen);
+	alen = nlh->nlmsg_len - hlen;
+
+	if (libbpf_nla_parse(tb, NLMSGERR_ATTR_MAX, attr, alen,
+			     extack_policy) != 0) {
+		pr_warn("Failed to parse extended error attributes\n");
+		return 0;
+	}
+
+	if (tb[NLMSGERR_ATTR_MSG])
+		errmsg = (char *) libbpf_nla_data(tb[NLMSGERR_ATTR_MSG]);
+
+	pr_warn("Kernel error message: %s\n", errmsg);
+
+	return 0;
+}
diff --git a/src/nlattr.h b/src/nlattr.h
new file mode 100644
index 0000000..4d15ae2
--- /dev/null
+++ b/src/nlattr.h
@@ -0,0 +1,164 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * NETLINK      Netlink attributes
+ *
+ * Copyright (c) 2003-2013 Thomas Graf <tgraf@suug.ch>
+ */
+
+#ifndef __LIBBPF_NLATTR_H
+#define __LIBBPF_NLATTR_H
+
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+
+/* avoid multiple definition of netlink features */
+#define __LINUX_NETLINK_H
+
+/**
+ * Standard attribute types to specify validation policy
+ */
+enum {
+	LIBBPF_NLA_UNSPEC,	/**< Unspecified type, binary data chunk */
+	LIBBPF_NLA_U8,		/**< 8 bit integer */
+	LIBBPF_NLA_U16,		/**< 16 bit integer */
+	LIBBPF_NLA_U32,		/**< 32 bit integer */
+	LIBBPF_NLA_U64,		/**< 64 bit integer */
+	LIBBPF_NLA_STRING,	/**< NUL terminated character string */
+	LIBBPF_NLA_FLAG,	/**< Flag */
+	LIBBPF_NLA_MSECS,	/**< Micro seconds (64bit) */
+	LIBBPF_NLA_NESTED,	/**< Nested attributes */
+	__LIBBPF_NLA_TYPE_MAX,
+};
+
+#define LIBBPF_NLA_TYPE_MAX (__LIBBPF_NLA_TYPE_MAX - 1)
+
+/**
+ * @ingroup attr
+ * Attribute validation policy.
+ *
+ * See section @core_doc{core_attr_parse,Attribute Parsing} for more details.
+ */
+struct libbpf_nla_policy {
+	/** Type of attribute or LIBBPF_NLA_UNSPEC */
+	uint16_t	type;
+
+	/** Minimal length of payload required */
+	uint16_t	minlen;
+
+	/** Maximal length of payload allowed */
+	uint16_t	maxlen;
+};
+
+struct libbpf_nla_req {
+	struct nlmsghdr nh;
+	union {
+		struct ifinfomsg ifinfo;
+		struct tcmsg tc;
+	};
+	char buf[128];
+};
+
+/**
+ * @ingroup attr
+ * Iterate over a stream of attributes
+ * @arg pos	loop counter, set to current attribute
+ * @arg head	head of attribute stream
+ * @arg len	length of attribute stream
+ * @arg rem	initialized to len, holds bytes currently remaining in stream
+ */
+#define libbpf_nla_for_each_attr(pos, head, len, rem) \
+	for (pos = head, rem = len; \
+	     nla_ok(pos, rem); \
+	     pos = nla_next(pos, &(rem)))
+
+/**
+ * libbpf_nla_data - head of payload
+ * @nla: netlink attribute
+ */
+static inline void *libbpf_nla_data(const struct nlattr *nla)
+{
+	return (void *)nla + NLA_HDRLEN;
+}
+
+static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla)
+{
+	return *(uint8_t *)libbpf_nla_data(nla);
+}
+
+static inline uint32_t libbpf_nla_getattr_u32(const struct nlattr *nla)
+{
+	return *(uint32_t *)libbpf_nla_data(nla);
+}
+
+static inline const char *libbpf_nla_getattr_str(const struct nlattr *nla)
+{
+	return (const char *)libbpf_nla_data(nla);
+}
+
+/**
+ * libbpf_nla_len - length of payload
+ * @nla: netlink attribute
+ */
+static inline int libbpf_nla_len(const struct nlattr *nla)
+{
+	return nla->nla_len - NLA_HDRLEN;
+}
+
+int libbpf_nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head,
+		     int len, struct libbpf_nla_policy *policy);
+int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype,
+			    struct nlattr *nla,
+			    struct libbpf_nla_policy *policy);
+
+int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh);
+
+static inline struct nlattr *nla_data(struct nlattr *nla)
+{
+	return (struct nlattr *)((void *)nla + NLA_HDRLEN);
+}
+
+static inline struct nlattr *req_tail(struct libbpf_nla_req *req)
+{
+	return (struct nlattr *)((void *)req + NLMSG_ALIGN(req->nh.nlmsg_len));
+}
+
+static inline int nlattr_add(struct libbpf_nla_req *req, int type,
+			     const void *data, int len)
+{
+	struct nlattr *nla;
+
+	if (NLMSG_ALIGN(req->nh.nlmsg_len) + NLA_ALIGN(NLA_HDRLEN + len) > sizeof(*req))
+		return -EMSGSIZE;
+	if (!!data != !!len)
+		return -EINVAL;
+
+	nla = req_tail(req);
+	nla->nla_type = type;
+	nla->nla_len = NLA_HDRLEN + len;
+	if (data)
+		memcpy(nla_data(nla), data, len);
+	req->nh.nlmsg_len = NLMSG_ALIGN(req->nh.nlmsg_len) + NLA_ALIGN(nla->nla_len);
+	return 0;
+}
+
+static inline struct nlattr *nlattr_begin_nested(struct libbpf_nla_req *req, int type)
+{
+	struct nlattr *tail;
+
+	tail = req_tail(req);
+	if (nlattr_add(req, type | NLA_F_NESTED, NULL, 0))
+		return NULL;
+	return tail;
+}
+
+static inline void nlattr_end_nested(struct libbpf_nla_req *req,
+				     struct nlattr *tail)
+{
+	tail->nla_len = (void *)req_tail(req) - (void *)tail;
+}
+
+#endif /* __LIBBPF_NLATTR_H */
diff --git a/src/relo_core.c b/src/relo_core.c
new file mode 100644
index 0000000..c4b0e81
--- /dev/null
+++ b/src/relo_core.c
@@ -0,0 +1,1690 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2019 Facebook */
+
+#ifdef __KERNEL__
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/string.h>
+#include <linux/bpf_verifier.h>
+#include "relo_core.h"
+
+static const char *btf_kind_str(const struct btf_type *t)
+{
+	return btf_type_str(t);
+}
+
+static bool is_ldimm64_insn(struct bpf_insn *insn)
+{
+	return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
+}
+
+static const struct btf_type *
+skip_mods_and_typedefs(const struct btf *btf, u32 id, u32 *res_id)
+{
+	return btf_type_skip_modifiers(btf, id, res_id);
+}
+
+static const char *btf__name_by_offset(const struct btf *btf, u32 offset)
+{
+	return btf_name_by_offset(btf, offset);
+}
+
+static s64 btf__resolve_size(const struct btf *btf, u32 type_id)
+{
+	const struct btf_type *t;
+	int size;
+
+	t = btf_type_by_id(btf, type_id);
+	t = btf_resolve_size(btf, t, &size);
+	if (IS_ERR(t))
+		return PTR_ERR(t);
+	return size;
+}
+
+enum libbpf_print_level {
+	LIBBPF_WARN,
+	LIBBPF_INFO,
+	LIBBPF_DEBUG,
+};
+
+#undef pr_warn
+#undef pr_info
+#undef pr_debug
+#define pr_warn(fmt, log, ...)	bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
+#define pr_info(fmt, log, ...)	bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
+#define pr_debug(fmt, log, ...)	bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
+#define libbpf_print(level, fmt, ...)	bpf_log((void *)prog_name, fmt, ##__VA_ARGS__)
+#else
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+#include <linux/err.h>
+
+#include "libbpf.h"
+#include "bpf.h"
+#include "btf.h"
+#include "str_error.h"
+#include "libbpf_internal.h"
+#endif
+
+static bool is_flex_arr(const struct btf *btf,
+			const struct bpf_core_accessor *acc,
+			const struct btf_array *arr)
+{
+	const struct btf_type *t;
+
+	/* not a flexible array, if not inside a struct or has non-zero size */
+	if (!acc->name || arr->nelems > 0)
+		return false;
+
+	/* has to be the last member of enclosing struct */
+	t = btf_type_by_id(btf, acc->type_id);
+	return acc->idx == btf_vlen(t) - 1;
+}
+
+static const char *core_relo_kind_str(enum bpf_core_relo_kind kind)
+{
+	switch (kind) {
+	case BPF_CORE_FIELD_BYTE_OFFSET: return "byte_off";
+	case BPF_CORE_FIELD_BYTE_SIZE: return "byte_sz";
+	case BPF_CORE_FIELD_EXISTS: return "field_exists";
+	case BPF_CORE_FIELD_SIGNED: return "signed";
+	case BPF_CORE_FIELD_LSHIFT_U64: return "lshift_u64";
+	case BPF_CORE_FIELD_RSHIFT_U64: return "rshift_u64";
+	case BPF_CORE_TYPE_ID_LOCAL: return "local_type_id";
+	case BPF_CORE_TYPE_ID_TARGET: return "target_type_id";
+	case BPF_CORE_TYPE_EXISTS: return "type_exists";
+	case BPF_CORE_TYPE_MATCHES: return "type_matches";
+	case BPF_CORE_TYPE_SIZE: return "type_size";
+	case BPF_CORE_ENUMVAL_EXISTS: return "enumval_exists";
+	case BPF_CORE_ENUMVAL_VALUE: return "enumval_value";
+	default: return "unknown";
+	}
+}
+
+static bool core_relo_is_field_based(enum bpf_core_relo_kind kind)
+{
+	switch (kind) {
+	case BPF_CORE_FIELD_BYTE_OFFSET:
+	case BPF_CORE_FIELD_BYTE_SIZE:
+	case BPF_CORE_FIELD_EXISTS:
+	case BPF_CORE_FIELD_SIGNED:
+	case BPF_CORE_FIELD_LSHIFT_U64:
+	case BPF_CORE_FIELD_RSHIFT_U64:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool core_relo_is_type_based(enum bpf_core_relo_kind kind)
+{
+	switch (kind) {
+	case BPF_CORE_TYPE_ID_LOCAL:
+	case BPF_CORE_TYPE_ID_TARGET:
+	case BPF_CORE_TYPE_EXISTS:
+	case BPF_CORE_TYPE_MATCHES:
+	case BPF_CORE_TYPE_SIZE:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool core_relo_is_enumval_based(enum bpf_core_relo_kind kind)
+{
+	switch (kind) {
+	case BPF_CORE_ENUMVAL_EXISTS:
+	case BPF_CORE_ENUMVAL_VALUE:
+		return true;
+	default:
+		return false;
+	}
+}
+
+int __bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
+				const struct btf *targ_btf, __u32 targ_id, int level)
+{
+	const struct btf_type *local_type, *targ_type;
+	int depth = 32; /* max recursion depth */
+
+	/* caller made sure that names match (ignoring flavor suffix) */
+	local_type = btf_type_by_id(local_btf, local_id);
+	targ_type = btf_type_by_id(targ_btf, targ_id);
+	if (!btf_kind_core_compat(local_type, targ_type))
+		return 0;
+
+recur:
+	depth--;
+	if (depth < 0)
+		return -EINVAL;
+
+	local_type = skip_mods_and_typedefs(local_btf, local_id, &local_id);
+	targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
+	if (!local_type || !targ_type)
+		return -EINVAL;
+
+	if (!btf_kind_core_compat(local_type, targ_type))
+		return 0;
+
+	switch (btf_kind(local_type)) {
+	case BTF_KIND_UNKN:
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+	case BTF_KIND_ENUM:
+	case BTF_KIND_FWD:
+	case BTF_KIND_ENUM64:
+		return 1;
+	case BTF_KIND_INT:
+		/* just reject deprecated bitfield-like integers; all other
+		 * integers are by default compatible between each other
+		 */
+		return btf_int_offset(local_type) == 0 && btf_int_offset(targ_type) == 0;
+	case BTF_KIND_PTR:
+		local_id = local_type->type;
+		targ_id = targ_type->type;
+		goto recur;
+	case BTF_KIND_ARRAY:
+		local_id = btf_array(local_type)->type;
+		targ_id = btf_array(targ_type)->type;
+		goto recur;
+	case BTF_KIND_FUNC_PROTO: {
+		struct btf_param *local_p = btf_params(local_type);
+		struct btf_param *targ_p = btf_params(targ_type);
+		__u16 local_vlen = btf_vlen(local_type);
+		__u16 targ_vlen = btf_vlen(targ_type);
+		int i, err;
+
+		if (local_vlen != targ_vlen)
+			return 0;
+
+		for (i = 0; i < local_vlen; i++, local_p++, targ_p++) {
+			if (level <= 0)
+				return -EINVAL;
+
+			skip_mods_and_typedefs(local_btf, local_p->type, &local_id);
+			skip_mods_and_typedefs(targ_btf, targ_p->type, &targ_id);
+			err = __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id,
+							  level - 1);
+			if (err <= 0)
+				return err;
+		}
+
+		/* tail recurse for return type check */
+		skip_mods_and_typedefs(local_btf, local_type->type, &local_id);
+		skip_mods_and_typedefs(targ_btf, targ_type->type, &targ_id);
+		goto recur;
+	}
+	default:
+		pr_warn("unexpected kind %s relocated, local [%d], target [%d]\n",
+			btf_kind_str(local_type), local_id, targ_id);
+		return 0;
+	}
+}
+
+/*
+ * Turn bpf_core_relo into a low- and high-level spec representation,
+ * validating correctness along the way, as well as calculating resulting
+ * field bit offset, specified by accessor string. Low-level spec captures
+ * every single level of nestedness, including traversing anonymous
+ * struct/union members. High-level one only captures semantically meaningful
+ * "turning points": named fields and array indicies.
+ * E.g., for this case:
+ *
+ *   struct sample {
+ *       int __unimportant;
+ *       struct {
+ *           int __1;
+ *           int __2;
+ *           int a[7];
+ *       };
+ *   };
+ *
+ *   struct sample *s = ...;
+ *
+ *   int x = &s->a[3]; // access string = '0:1:2:3'
+ *
+ * Low-level spec has 1:1 mapping with each element of access string (it's
+ * just a parsed access string representation): [0, 1, 2, 3].
+ *
+ * High-level spec will capture only 3 points:
+ *   - initial zero-index access by pointer (&s->... is the same as &s[0]...);
+ *   - field 'a' access (corresponds to '2' in low-level spec);
+ *   - array element #3 access (corresponds to '3' in low-level spec).
+ *
+ * Type-based relocations (TYPE_EXISTS/TYPE_MATCHES/TYPE_SIZE,
+ * TYPE_ID_LOCAL/TYPE_ID_TARGET) don't capture any field information. Their
+ * spec and raw_spec are kept empty.
+ *
+ * Enum value-based relocations (ENUMVAL_EXISTS/ENUMVAL_VALUE) use access
+ * string to specify enumerator's value index that need to be relocated.
+ */
+int bpf_core_parse_spec(const char *prog_name, const struct btf *btf,
+			const struct bpf_core_relo *relo,
+			struct bpf_core_spec *spec)
+{
+	int access_idx, parsed_len, i;
+	struct bpf_core_accessor *acc;
+	const struct btf_type *t;
+	const char *name, *spec_str;
+	__u32 id, name_off;
+	__s64 sz;
+
+	spec_str = btf__name_by_offset(btf, relo->access_str_off);
+	if (str_is_empty(spec_str) || *spec_str == ':')
+		return -EINVAL;
+
+	memset(spec, 0, sizeof(*spec));
+	spec->btf = btf;
+	spec->root_type_id = relo->type_id;
+	spec->relo_kind = relo->kind;
+
+	/* type-based relocations don't have a field access string */
+	if (core_relo_is_type_based(relo->kind)) {
+		if (strcmp(spec_str, "0"))
+			return -EINVAL;
+		return 0;
+	}
+
+	/* parse spec_str="0:1:2:3:4" into array raw_spec=[0, 1, 2, 3, 4] */
+	while (*spec_str) {
+		if (*spec_str == ':')
+			++spec_str;
+		if (sscanf(spec_str, "%d%n", &access_idx, &parsed_len) != 1)
+			return -EINVAL;
+		if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
+			return -E2BIG;
+		spec_str += parsed_len;
+		spec->raw_spec[spec->raw_len++] = access_idx;
+	}
+
+	if (spec->raw_len == 0)
+		return -EINVAL;
+
+	t = skip_mods_and_typedefs(btf, relo->type_id, &id);
+	if (!t)
+		return -EINVAL;
+
+	access_idx = spec->raw_spec[0];
+	acc = &spec->spec[0];
+	acc->type_id = id;
+	acc->idx = access_idx;
+	spec->len++;
+
+	if (core_relo_is_enumval_based(relo->kind)) {
+		if (!btf_is_any_enum(t) || spec->raw_len > 1 || access_idx >= btf_vlen(t))
+			return -EINVAL;
+
+		/* record enumerator name in a first accessor */
+		name_off = btf_is_enum(t) ? btf_enum(t)[access_idx].name_off
+					  : btf_enum64(t)[access_idx].name_off;
+		acc->name = btf__name_by_offset(btf, name_off);
+		return 0;
+	}
+
+	if (!core_relo_is_field_based(relo->kind))
+		return -EINVAL;
+
+	sz = btf__resolve_size(btf, id);
+	if (sz < 0)
+		return sz;
+	spec->bit_offset = access_idx * sz * 8;
+
+	for (i = 1; i < spec->raw_len; i++) {
+		t = skip_mods_and_typedefs(btf, id, &id);
+		if (!t)
+			return -EINVAL;
+
+		access_idx = spec->raw_spec[i];
+		acc = &spec->spec[spec->len];
+
+		if (btf_is_composite(t)) {
+			const struct btf_member *m;
+			__u32 bit_offset;
+
+			if (access_idx >= btf_vlen(t))
+				return -EINVAL;
+
+			bit_offset = btf_member_bit_offset(t, access_idx);
+			spec->bit_offset += bit_offset;
+
+			m = btf_members(t) + access_idx;
+			if (m->name_off) {
+				name = btf__name_by_offset(btf, m->name_off);
+				if (str_is_empty(name))
+					return -EINVAL;
+
+				acc->type_id = id;
+				acc->idx = access_idx;
+				acc->name = name;
+				spec->len++;
+			}
+
+			id = m->type;
+		} else if (btf_is_array(t)) {
+			const struct btf_array *a = btf_array(t);
+			bool flex;
+
+			t = skip_mods_and_typedefs(btf, a->type, &id);
+			if (!t)
+				return -EINVAL;
+
+			flex = is_flex_arr(btf, acc - 1, a);
+			if (!flex && access_idx >= a->nelems)
+				return -EINVAL;
+
+			spec->spec[spec->len].type_id = id;
+			spec->spec[spec->len].idx = access_idx;
+			spec->len++;
+
+			sz = btf__resolve_size(btf, id);
+			if (sz < 0)
+				return sz;
+			spec->bit_offset += access_idx * sz * 8;
+		} else {
+			pr_warn("prog '%s': relo for [%u] %s (at idx %d) captures type [%d] of unexpected kind %s\n",
+				prog_name, relo->type_id, spec_str, i, id, btf_kind_str(t));
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/* Check two types for compatibility for the purpose of field access
+ * relocation. const/volatile/restrict and typedefs are skipped to ensure we
+ * are relocating semantically compatible entities:
+ *   - any two STRUCTs/UNIONs are compatible and can be mixed;
+ *   - any two FWDs are compatible, if their names match (modulo flavor suffix);
+ *   - any two PTRs are always compatible;
+ *   - for ENUMs, names should be the same (ignoring flavor suffix) or at
+ *     least one of enums should be anonymous;
+ *   - for ENUMs, check sizes, names are ignored;
+ *   - for INT, size and signedness are ignored;
+ *   - any two FLOATs are always compatible;
+ *   - for ARRAY, dimensionality is ignored, element types are checked for
+ *     compatibility recursively;
+ *   - everything else shouldn't be ever a target of relocation.
+ * These rules are not set in stone and probably will be adjusted as we get
+ * more experience with using BPF CO-RE relocations.
+ */
+static int bpf_core_fields_are_compat(const struct btf *local_btf,
+				      __u32 local_id,
+				      const struct btf *targ_btf,
+				      __u32 targ_id)
+{
+	const struct btf_type *local_type, *targ_type;
+
+recur:
+	local_type = skip_mods_and_typedefs(local_btf, local_id, &local_id);
+	targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
+	if (!local_type || !targ_type)
+		return -EINVAL;
+
+	if (btf_is_composite(local_type) && btf_is_composite(targ_type))
+		return 1;
+	if (!btf_kind_core_compat(local_type, targ_type))
+		return 0;
+
+	switch (btf_kind(local_type)) {
+	case BTF_KIND_PTR:
+	case BTF_KIND_FLOAT:
+		return 1;
+	case BTF_KIND_FWD:
+	case BTF_KIND_ENUM64:
+	case BTF_KIND_ENUM: {
+		const char *local_name, *targ_name;
+		size_t local_len, targ_len;
+
+		local_name = btf__name_by_offset(local_btf,
+						 local_type->name_off);
+		targ_name = btf__name_by_offset(targ_btf, targ_type->name_off);
+		local_len = bpf_core_essential_name_len(local_name);
+		targ_len = bpf_core_essential_name_len(targ_name);
+		/* one of them is anonymous or both w/ same flavor-less names */
+		return local_len == 0 || targ_len == 0 ||
+		       (local_len == targ_len &&
+			strncmp(local_name, targ_name, local_len) == 0);
+	}
+	case BTF_KIND_INT:
+		/* just reject deprecated bitfield-like integers; all other
+		 * integers are by default compatible between each other
+		 */
+		return btf_int_offset(local_type) == 0 &&
+		       btf_int_offset(targ_type) == 0;
+	case BTF_KIND_ARRAY:
+		local_id = btf_array(local_type)->type;
+		targ_id = btf_array(targ_type)->type;
+		goto recur;
+	default:
+		return 0;
+	}
+}
+
+/*
+ * Given single high-level named field accessor in local type, find
+ * corresponding high-level accessor for a target type. Along the way,
+ * maintain low-level spec for target as well. Also keep updating target
+ * bit offset.
+ *
+ * Searching is performed through recursive exhaustive enumeration of all
+ * fields of a struct/union. If there are any anonymous (embedded)
+ * structs/unions, they are recursively searched as well. If field with
+ * desired name is found, check compatibility between local and target types,
+ * before returning result.
+ *
+ * 1 is returned, if field is found.
+ * 0 is returned if no compatible field is found.
+ * <0 is returned on error.
+ */
+static int bpf_core_match_member(const struct btf *local_btf,
+				 const struct bpf_core_accessor *local_acc,
+				 const struct btf *targ_btf,
+				 __u32 targ_id,
+				 struct bpf_core_spec *spec,
+				 __u32 *next_targ_id)
+{
+	const struct btf_type *local_type, *targ_type;
+	const struct btf_member *local_member, *m;
+	const char *local_name, *targ_name;
+	__u32 local_id;
+	int i, n, found;
+
+	targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
+	if (!targ_type)
+		return -EINVAL;
+	if (!btf_is_composite(targ_type))
+		return 0;
+
+	local_id = local_acc->type_id;
+	local_type = btf_type_by_id(local_btf, local_id);
+	local_member = btf_members(local_type) + local_acc->idx;
+	local_name = btf__name_by_offset(local_btf, local_member->name_off);
+
+	n = btf_vlen(targ_type);
+	m = btf_members(targ_type);
+	for (i = 0; i < n; i++, m++) {
+		__u32 bit_offset;
+
+		bit_offset = btf_member_bit_offset(targ_type, i);
+
+		/* too deep struct/union/array nesting */
+		if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
+			return -E2BIG;
+
+		/* speculate this member will be the good one */
+		spec->bit_offset += bit_offset;
+		spec->raw_spec[spec->raw_len++] = i;
+
+		targ_name = btf__name_by_offset(targ_btf, m->name_off);
+		if (str_is_empty(targ_name)) {
+			/* embedded struct/union, we need to go deeper */
+			found = bpf_core_match_member(local_btf, local_acc,
+						      targ_btf, m->type,
+						      spec, next_targ_id);
+			if (found) /* either found or error */
+				return found;
+		} else if (strcmp(local_name, targ_name) == 0) {
+			/* matching named field */
+			struct bpf_core_accessor *targ_acc;
+
+			targ_acc = &spec->spec[spec->len++];
+			targ_acc->type_id = targ_id;
+			targ_acc->idx = i;
+			targ_acc->name = targ_name;
+
+			*next_targ_id = m->type;
+			found = bpf_core_fields_are_compat(local_btf,
+							   local_member->type,
+							   targ_btf, m->type);
+			if (!found)
+				spec->len--; /* pop accessor */
+			return found;
+		}
+		/* member turned out not to be what we looked for */
+		spec->bit_offset -= bit_offset;
+		spec->raw_len--;
+	}
+
+	return 0;
+}
+
+/*
+ * Try to match local spec to a target type and, if successful, produce full
+ * target spec (high-level, low-level + bit offset).
+ */
+static int bpf_core_spec_match(struct bpf_core_spec *local_spec,
+			       const struct btf *targ_btf, __u32 targ_id,
+			       struct bpf_core_spec *targ_spec)
+{
+	const struct btf_type *targ_type;
+	const struct bpf_core_accessor *local_acc;
+	struct bpf_core_accessor *targ_acc;
+	int i, sz, matched;
+	__u32 name_off;
+
+	memset(targ_spec, 0, sizeof(*targ_spec));
+	targ_spec->btf = targ_btf;
+	targ_spec->root_type_id = targ_id;
+	targ_spec->relo_kind = local_spec->relo_kind;
+
+	if (core_relo_is_type_based(local_spec->relo_kind)) {
+		if (local_spec->relo_kind == BPF_CORE_TYPE_MATCHES)
+			return bpf_core_types_match(local_spec->btf,
+						    local_spec->root_type_id,
+						    targ_btf, targ_id);
+		else
+			return bpf_core_types_are_compat(local_spec->btf,
+							 local_spec->root_type_id,
+							 targ_btf, targ_id);
+	}
+
+	local_acc = &local_spec->spec[0];
+	targ_acc = &targ_spec->spec[0];
+
+	if (core_relo_is_enumval_based(local_spec->relo_kind)) {
+		size_t local_essent_len, targ_essent_len;
+		const char *targ_name;
+
+		/* has to resolve to an enum */
+		targ_type = skip_mods_and_typedefs(targ_spec->btf, targ_id, &targ_id);
+		if (!btf_is_any_enum(targ_type))
+			return 0;
+
+		local_essent_len = bpf_core_essential_name_len(local_acc->name);
+
+		for (i = 0; i < btf_vlen(targ_type); i++) {
+			if (btf_is_enum(targ_type))
+				name_off = btf_enum(targ_type)[i].name_off;
+			else
+				name_off = btf_enum64(targ_type)[i].name_off;
+
+			targ_name = btf__name_by_offset(targ_spec->btf, name_off);
+			targ_essent_len = bpf_core_essential_name_len(targ_name);
+			if (targ_essent_len != local_essent_len)
+				continue;
+			if (strncmp(local_acc->name, targ_name, local_essent_len) == 0) {
+				targ_acc->type_id = targ_id;
+				targ_acc->idx = i;
+				targ_acc->name = targ_name;
+				targ_spec->len++;
+				targ_spec->raw_spec[targ_spec->raw_len] = targ_acc->idx;
+				targ_spec->raw_len++;
+				return 1;
+			}
+		}
+		return 0;
+	}
+
+	if (!core_relo_is_field_based(local_spec->relo_kind))
+		return -EINVAL;
+
+	for (i = 0; i < local_spec->len; i++, local_acc++, targ_acc++) {
+		targ_type = skip_mods_and_typedefs(targ_spec->btf, targ_id,
+						   &targ_id);
+		if (!targ_type)
+			return -EINVAL;
+
+		if (local_acc->name) {
+			matched = bpf_core_match_member(local_spec->btf,
+							local_acc,
+							targ_btf, targ_id,
+							targ_spec, &targ_id);
+			if (matched <= 0)
+				return matched;
+		} else {
+			/* for i=0, targ_id is already treated as array element
+			 * type (because it's the original struct), for others
+			 * we should find array element type first
+			 */
+			if (i > 0) {
+				const struct btf_array *a;
+				bool flex;
+
+				if (!btf_is_array(targ_type))
+					return 0;
+
+				a = btf_array(targ_type);
+				flex = is_flex_arr(targ_btf, targ_acc - 1, a);
+				if (!flex && local_acc->idx >= a->nelems)
+					return 0;
+				if (!skip_mods_and_typedefs(targ_btf, a->type,
+							    &targ_id))
+					return -EINVAL;
+			}
+
+			/* too deep struct/union/array nesting */
+			if (targ_spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
+				return -E2BIG;
+
+			targ_acc->type_id = targ_id;
+			targ_acc->idx = local_acc->idx;
+			targ_acc->name = NULL;
+			targ_spec->len++;
+			targ_spec->raw_spec[targ_spec->raw_len] = targ_acc->idx;
+			targ_spec->raw_len++;
+
+			sz = btf__resolve_size(targ_btf, targ_id);
+			if (sz < 0)
+				return sz;
+			targ_spec->bit_offset += local_acc->idx * sz * 8;
+		}
+	}
+
+	return 1;
+}
+
+static int bpf_core_calc_field_relo(const char *prog_name,
+				    const struct bpf_core_relo *relo,
+				    const struct bpf_core_spec *spec,
+				    __u64 *val, __u32 *field_sz, __u32 *type_id,
+				    bool *validate)
+{
+	const struct bpf_core_accessor *acc;
+	const struct btf_type *t;
+	__u32 byte_off, byte_sz, bit_off, bit_sz, field_type_id;
+	const struct btf_member *m;
+	const struct btf_type *mt;
+	bool bitfield;
+	__s64 sz;
+
+	*field_sz = 0;
+
+	if (relo->kind == BPF_CORE_FIELD_EXISTS) {
+		*val = spec ? 1 : 0;
+		return 0;
+	}
+
+	if (!spec)
+		return -EUCLEAN; /* request instruction poisoning */
+
+	acc = &spec->spec[spec->len - 1];
+	t = btf_type_by_id(spec->btf, acc->type_id);
+
+	/* a[n] accessor needs special handling */
+	if (!acc->name) {
+		if (relo->kind == BPF_CORE_FIELD_BYTE_OFFSET) {
+			*val = spec->bit_offset / 8;
+			/* remember field size for load/store mem size */
+			sz = btf__resolve_size(spec->btf, acc->type_id);
+			if (sz < 0)
+				return -EINVAL;
+			*field_sz = sz;
+			*type_id = acc->type_id;
+		} else if (relo->kind == BPF_CORE_FIELD_BYTE_SIZE) {
+			sz = btf__resolve_size(spec->btf, acc->type_id);
+			if (sz < 0)
+				return -EINVAL;
+			*val = sz;
+		} else {
+			pr_warn("prog '%s': relo %d at insn #%d can't be applied to array access\n",
+				prog_name, relo->kind, relo->insn_off / 8);
+			return -EINVAL;
+		}
+		if (validate)
+			*validate = true;
+		return 0;
+	}
+
+	m = btf_members(t) + acc->idx;
+	mt = skip_mods_and_typedefs(spec->btf, m->type, &field_type_id);
+	bit_off = spec->bit_offset;
+	bit_sz = btf_member_bitfield_size(t, acc->idx);
+
+	bitfield = bit_sz > 0;
+	if (bitfield) {
+		byte_sz = mt->size;
+		byte_off = bit_off / 8 / byte_sz * byte_sz;
+		/* figure out smallest int size necessary for bitfield load */
+		while (bit_off + bit_sz - byte_off * 8 > byte_sz * 8) {
+			if (byte_sz >= 8) {
+				/* bitfield can't be read with 64-bit read */
+				pr_warn("prog '%s': relo %d at insn #%d can't be satisfied for bitfield\n",
+					prog_name, relo->kind, relo->insn_off / 8);
+				return -E2BIG;
+			}
+			byte_sz *= 2;
+			byte_off = bit_off / 8 / byte_sz * byte_sz;
+		}
+	} else {
+		sz = btf__resolve_size(spec->btf, field_type_id);
+		if (sz < 0)
+			return -EINVAL;
+		byte_sz = sz;
+		byte_off = spec->bit_offset / 8;
+		bit_sz = byte_sz * 8;
+	}
+
+	/* for bitfields, all the relocatable aspects are ambiguous and we
+	 * might disagree with compiler, so turn off validation of expected
+	 * value, except for signedness
+	 */
+	if (validate)
+		*validate = !bitfield;
+
+	switch (relo->kind) {
+	case BPF_CORE_FIELD_BYTE_OFFSET:
+		*val = byte_off;
+		if (!bitfield) {
+			*field_sz = byte_sz;
+			*type_id = field_type_id;
+		}
+		break;
+	case BPF_CORE_FIELD_BYTE_SIZE:
+		*val = byte_sz;
+		break;
+	case BPF_CORE_FIELD_SIGNED:
+		*val = (btf_is_any_enum(mt) && BTF_INFO_KFLAG(mt->info)) ||
+		       (btf_int_encoding(mt) & BTF_INT_SIGNED);
+		if (validate)
+			*validate = true; /* signedness is never ambiguous */
+		break;
+	case BPF_CORE_FIELD_LSHIFT_U64:
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+		*val = 64 - (bit_off + bit_sz - byte_off  * 8);
+#else
+		*val = (8 - byte_sz) * 8 + (bit_off - byte_off * 8);
+#endif
+		break;
+	case BPF_CORE_FIELD_RSHIFT_U64:
+		*val = 64 - bit_sz;
+		if (validate)
+			*validate = true; /* right shift is never ambiguous */
+		break;
+	case BPF_CORE_FIELD_EXISTS:
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int bpf_core_calc_type_relo(const struct bpf_core_relo *relo,
+				   const struct bpf_core_spec *spec,
+				   __u64 *val, bool *validate)
+{
+	__s64 sz;
+
+	/* by default, always check expected value in bpf_insn */
+	if (validate)
+		*validate = true;
+
+	/* type-based relos return zero when target type is not found */
+	if (!spec) {
+		*val = 0;
+		return 0;
+	}
+
+	switch (relo->kind) {
+	case BPF_CORE_TYPE_ID_TARGET:
+		*val = spec->root_type_id;
+		/* type ID, embedded in bpf_insn, might change during linking,
+		 * so enforcing it is pointless
+		 */
+		if (validate)
+			*validate = false;
+		break;
+	case BPF_CORE_TYPE_EXISTS:
+	case BPF_CORE_TYPE_MATCHES:
+		*val = 1;
+		break;
+	case BPF_CORE_TYPE_SIZE:
+		sz = btf__resolve_size(spec->btf, spec->root_type_id);
+		if (sz < 0)
+			return -EINVAL;
+		*val = sz;
+		break;
+	case BPF_CORE_TYPE_ID_LOCAL:
+	/* BPF_CORE_TYPE_ID_LOCAL is handled specially and shouldn't get here */
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int bpf_core_calc_enumval_relo(const struct bpf_core_relo *relo,
+				      const struct bpf_core_spec *spec,
+				      __u64 *val)
+{
+	const struct btf_type *t;
+
+	switch (relo->kind) {
+	case BPF_CORE_ENUMVAL_EXISTS:
+		*val = spec ? 1 : 0;
+		break;
+	case BPF_CORE_ENUMVAL_VALUE:
+		if (!spec)
+			return -EUCLEAN; /* request instruction poisoning */
+		t = btf_type_by_id(spec->btf, spec->spec[0].type_id);
+		if (btf_is_enum(t))
+			*val = btf_enum(t)[spec->spec[0].idx].val;
+		else
+			*val = btf_enum64_value(btf_enum64(t) + spec->spec[0].idx);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+/* Calculate original and target relocation values, given local and target
+ * specs and relocation kind. These values are calculated for each candidate.
+ * If there are multiple candidates, resulting values should all be consistent
+ * with each other. Otherwise, libbpf will refuse to proceed due to ambiguity.
+ * If instruction has to be poisoned, *poison will be set to true.
+ */
+static int bpf_core_calc_relo(const char *prog_name,
+			      const struct bpf_core_relo *relo,
+			      int relo_idx,
+			      const struct bpf_core_spec *local_spec,
+			      const struct bpf_core_spec *targ_spec,
+			      struct bpf_core_relo_res *res)
+{
+	int err = -EOPNOTSUPP;
+
+	res->orig_val = 0;
+	res->new_val = 0;
+	res->poison = false;
+	res->validate = true;
+	res->fail_memsz_adjust = false;
+	res->orig_sz = res->new_sz = 0;
+	res->orig_type_id = res->new_type_id = 0;
+
+	if (core_relo_is_field_based(relo->kind)) {
+		err = bpf_core_calc_field_relo(prog_name, relo, local_spec,
+					       &res->orig_val, &res->orig_sz,
+					       &res->orig_type_id, &res->validate);
+		err = err ?: bpf_core_calc_field_relo(prog_name, relo, targ_spec,
+						      &res->new_val, &res->new_sz,
+						      &res->new_type_id, NULL);
+		if (err)
+			goto done;
+		/* Validate if it's safe to adjust load/store memory size.
+		 * Adjustments are performed only if original and new memory
+		 * sizes differ.
+		 */
+		res->fail_memsz_adjust = false;
+		if (res->orig_sz != res->new_sz) {
+			const struct btf_type *orig_t, *new_t;
+
+			orig_t = btf_type_by_id(local_spec->btf, res->orig_type_id);
+			new_t = btf_type_by_id(targ_spec->btf, res->new_type_id);
+
+			/* There are two use cases in which it's safe to
+			 * adjust load/store's mem size:
+			 *   - reading a 32-bit kernel pointer, while on BPF
+			 *   size pointers are always 64-bit; in this case
+			 *   it's safe to "downsize" instruction size due to
+			 *   pointer being treated as unsigned integer with
+			 *   zero-extended upper 32-bits;
+			 *   - reading unsigned integers, again due to
+			 *   zero-extension is preserving the value correctly.
+			 *
+			 * In all other cases it's incorrect to attempt to
+			 * load/store field because read value will be
+			 * incorrect, so we poison relocated instruction.
+			 */
+			if (btf_is_ptr(orig_t) && btf_is_ptr(new_t))
+				goto done;
+			if (btf_is_int(orig_t) && btf_is_int(new_t) &&
+			    btf_int_encoding(orig_t) != BTF_INT_SIGNED &&
+			    btf_int_encoding(new_t) != BTF_INT_SIGNED)
+				goto done;
+
+			/* mark as invalid mem size adjustment, but this will
+			 * only be checked for LDX/STX/ST insns
+			 */
+			res->fail_memsz_adjust = true;
+		}
+	} else if (core_relo_is_type_based(relo->kind)) {
+		err = bpf_core_calc_type_relo(relo, local_spec, &res->orig_val, &res->validate);
+		err = err ?: bpf_core_calc_type_relo(relo, targ_spec, &res->new_val, NULL);
+	} else if (core_relo_is_enumval_based(relo->kind)) {
+		err = bpf_core_calc_enumval_relo(relo, local_spec, &res->orig_val);
+		err = err ?: bpf_core_calc_enumval_relo(relo, targ_spec, &res->new_val);
+	}
+
+done:
+	if (err == -EUCLEAN) {
+		/* EUCLEAN is used to signal instruction poisoning request */
+		res->poison = true;
+		err = 0;
+	} else if (err == -EOPNOTSUPP) {
+		/* EOPNOTSUPP means unknown/unsupported relocation */
+		pr_warn("prog '%s': relo #%d: unrecognized CO-RE relocation %s (%d) at insn #%d\n",
+			prog_name, relo_idx, core_relo_kind_str(relo->kind),
+			relo->kind, relo->insn_off / 8);
+	}
+
+	return err;
+}
+
+/*
+ * Turn instruction for which CO_RE relocation failed into invalid one with
+ * distinct signature.
+ */
+static void bpf_core_poison_insn(const char *prog_name, int relo_idx,
+				 int insn_idx, struct bpf_insn *insn)
+{
+	pr_debug("prog '%s': relo #%d: substituting insn #%d w/ invalid insn\n",
+		 prog_name, relo_idx, insn_idx);
+	insn->code = BPF_JMP | BPF_CALL;
+	insn->dst_reg = 0;
+	insn->src_reg = 0;
+	insn->off = 0;
+	/* if this instruction is reachable (not a dead code),
+	 * verifier will complain with the following message:
+	 * invalid func unknown#195896080
+	 */
+	insn->imm = 195896080; /* => 0xbad2310 => "bad relo" */
+}
+
+static int insn_bpf_size_to_bytes(struct bpf_insn *insn)
+{
+	switch (BPF_SIZE(insn->code)) {
+	case BPF_DW: return 8;
+	case BPF_W: return 4;
+	case BPF_H: return 2;
+	case BPF_B: return 1;
+	default: return -1;
+	}
+}
+
+static int insn_bytes_to_bpf_size(__u32 sz)
+{
+	switch (sz) {
+	case 8: return BPF_DW;
+	case 4: return BPF_W;
+	case 2: return BPF_H;
+	case 1: return BPF_B;
+	default: return -1;
+	}
+}
+
+/*
+ * Patch relocatable BPF instruction.
+ *
+ * Patched value is determined by relocation kind and target specification.
+ * For existence relocations target spec will be NULL if field/type is not found.
+ * Expected insn->imm value is determined using relocation kind and local
+ * spec, and is checked before patching instruction. If actual insn->imm value
+ * is wrong, bail out with error.
+ *
+ * Currently supported classes of BPF instruction are:
+ * 1. rX = <imm> (assignment with immediate operand);
+ * 2. rX += <imm> (arithmetic operations with immediate operand);
+ * 3. rX = <imm64> (load with 64-bit immediate value);
+ * 4. rX = *(T *)(rY + <off>), where T is one of {u8, u16, u32, u64};
+ * 5. *(T *)(rX + <off>) = rY, where T is one of {u8, u16, u32, u64};
+ * 6. *(T *)(rX + <off>) = <imm>, where T is one of {u8, u16, u32, u64}.
+ */
+int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn,
+			int insn_idx, const struct bpf_core_relo *relo,
+			int relo_idx, const struct bpf_core_relo_res *res)
+{
+	__u64 orig_val, new_val;
+	__u8 class;
+
+	class = BPF_CLASS(insn->code);
+
+	if (res->poison) {
+poison:
+		/* poison second part of ldimm64 to avoid confusing error from
+		 * verifier about "unknown opcode 00"
+		 */
+		if (is_ldimm64_insn(insn))
+			bpf_core_poison_insn(prog_name, relo_idx, insn_idx + 1, insn + 1);
+		bpf_core_poison_insn(prog_name, relo_idx, insn_idx, insn);
+		return 0;
+	}
+
+	orig_val = res->orig_val;
+	new_val = res->new_val;
+
+	switch (class) {
+	case BPF_ALU:
+	case BPF_ALU64:
+		if (BPF_SRC(insn->code) != BPF_K)
+			return -EINVAL;
+		if (res->validate && insn->imm != orig_val) {
+			pr_warn("prog '%s': relo #%d: unexpected insn #%d (ALU/ALU64) value: got %u, exp %llu -> %llu\n",
+				prog_name, relo_idx,
+				insn_idx, insn->imm, (unsigned long long)orig_val,
+				(unsigned long long)new_val);
+			return -EINVAL;
+		}
+		orig_val = insn->imm;
+		insn->imm = new_val;
+		pr_debug("prog '%s': relo #%d: patched insn #%d (ALU/ALU64) imm %llu -> %llu\n",
+			 prog_name, relo_idx, insn_idx,
+			 (unsigned long long)orig_val, (unsigned long long)new_val);
+		break;
+	case BPF_LDX:
+	case BPF_ST:
+	case BPF_STX:
+		if (res->validate && insn->off != orig_val) {
+			pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDX/ST/STX) value: got %u, exp %llu -> %llu\n",
+				prog_name, relo_idx, insn_idx, insn->off, (unsigned long long)orig_val,
+				(unsigned long long)new_val);
+			return -EINVAL;
+		}
+		if (new_val > SHRT_MAX) {
+			pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) value too big: %llu\n",
+				prog_name, relo_idx, insn_idx, (unsigned long long)new_val);
+			return -ERANGE;
+		}
+		if (res->fail_memsz_adjust) {
+			pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) accesses field incorrectly. "
+				"Make sure you are accessing pointers, unsigned integers, or fields of matching type and size.\n",
+				prog_name, relo_idx, insn_idx);
+			goto poison;
+		}
+
+		orig_val = insn->off;
+		insn->off = new_val;
+		pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) off %llu -> %llu\n",
+			 prog_name, relo_idx, insn_idx, (unsigned long long)orig_val,
+			 (unsigned long long)new_val);
+
+		if (res->new_sz != res->orig_sz) {
+			int insn_bytes_sz, insn_bpf_sz;
+
+			insn_bytes_sz = insn_bpf_size_to_bytes(insn);
+			if (insn_bytes_sz != res->orig_sz) {
+				pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) unexpected mem size: got %d, exp %u\n",
+					prog_name, relo_idx, insn_idx, insn_bytes_sz, res->orig_sz);
+				return -EINVAL;
+			}
+
+			insn_bpf_sz = insn_bytes_to_bpf_size(res->new_sz);
+			if (insn_bpf_sz < 0) {
+				pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) invalid new mem size: %u\n",
+					prog_name, relo_idx, insn_idx, res->new_sz);
+				return -EINVAL;
+			}
+
+			insn->code = BPF_MODE(insn->code) | insn_bpf_sz | BPF_CLASS(insn->code);
+			pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) mem_sz %u -> %u\n",
+				 prog_name, relo_idx, insn_idx, res->orig_sz, res->new_sz);
+		}
+		break;
+	case BPF_LD: {
+		__u64 imm;
+
+		if (!is_ldimm64_insn(insn) ||
+		    insn[0].src_reg != 0 || insn[0].off != 0 ||
+		    insn[1].code != 0 || insn[1].dst_reg != 0 ||
+		    insn[1].src_reg != 0 || insn[1].off != 0) {
+			pr_warn("prog '%s': relo #%d: insn #%d (LDIMM64) has unexpected form\n",
+				prog_name, relo_idx, insn_idx);
+			return -EINVAL;
+		}
+
+		imm = (__u32)insn[0].imm | ((__u64)insn[1].imm << 32);
+		if (res->validate && imm != orig_val) {
+			pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDIMM64) value: got %llu, exp %llu -> %llu\n",
+				prog_name, relo_idx,
+				insn_idx, (unsigned long long)imm,
+				(unsigned long long)orig_val, (unsigned long long)new_val);
+			return -EINVAL;
+		}
+
+		insn[0].imm = new_val;
+		insn[1].imm = new_val >> 32;
+		pr_debug("prog '%s': relo #%d: patched insn #%d (LDIMM64) imm64 %llu -> %llu\n",
+			 prog_name, relo_idx, insn_idx,
+			 (unsigned long long)imm, (unsigned long long)new_val);
+		break;
+	}
+	default:
+		pr_warn("prog '%s': relo #%d: trying to relocate unrecognized insn #%d, code:0x%x, src:0x%x, dst:0x%x, off:0x%x, imm:0x%x\n",
+			prog_name, relo_idx, insn_idx, insn->code,
+			insn->src_reg, insn->dst_reg, insn->off, insn->imm);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* Output spec definition in the format:
+ * [<type-id>] (<type-name>) + <raw-spec> => <offset>@<spec>,
+ * where <spec> is a C-syntax view of recorded field access, e.g.: x.a[3].b
+ */
+int bpf_core_format_spec(char *buf, size_t buf_sz, const struct bpf_core_spec *spec)
+{
+	const struct btf_type *t;
+	const char *s;
+	__u32 type_id;
+	int i, len = 0;
+
+#define append_buf(fmt, args...)				\
+	({							\
+		int r;						\
+		r = snprintf(buf, buf_sz, fmt, ##args);		\
+		len += r;					\
+		if (r >= buf_sz)				\
+			r = buf_sz;				\
+		buf += r;					\
+		buf_sz -= r;					\
+	})
+
+	type_id = spec->root_type_id;
+	t = btf_type_by_id(spec->btf, type_id);
+	s = btf__name_by_offset(spec->btf, t->name_off);
+
+	append_buf("<%s> [%u] %s %s",
+		   core_relo_kind_str(spec->relo_kind),
+		   type_id, btf_kind_str(t), str_is_empty(s) ? "<anon>" : s);
+
+	if (core_relo_is_type_based(spec->relo_kind))
+		return len;
+
+	if (core_relo_is_enumval_based(spec->relo_kind)) {
+		t = skip_mods_and_typedefs(spec->btf, type_id, NULL);
+		if (btf_is_enum(t)) {
+			const struct btf_enum *e;
+			const char *fmt_str;
+
+			e = btf_enum(t) + spec->raw_spec[0];
+			s = btf__name_by_offset(spec->btf, e->name_off);
+			fmt_str = BTF_INFO_KFLAG(t->info) ? "::%s = %d" : "::%s = %u";
+			append_buf(fmt_str, s, e->val);
+		} else {
+			const struct btf_enum64 *e;
+			const char *fmt_str;
+
+			e = btf_enum64(t) + spec->raw_spec[0];
+			s = btf__name_by_offset(spec->btf, e->name_off);
+			fmt_str = BTF_INFO_KFLAG(t->info) ? "::%s = %lld" : "::%s = %llu";
+			append_buf(fmt_str, s, (unsigned long long)btf_enum64_value(e));
+		}
+		return len;
+	}
+
+	if (core_relo_is_field_based(spec->relo_kind)) {
+		for (i = 0; i < spec->len; i++) {
+			if (spec->spec[i].name)
+				append_buf(".%s", spec->spec[i].name);
+			else if (i > 0 || spec->spec[i].idx > 0)
+				append_buf("[%u]", spec->spec[i].idx);
+		}
+
+		append_buf(" (");
+		for (i = 0; i < spec->raw_len; i++)
+			append_buf("%s%d", i == 0 ? "" : ":", spec->raw_spec[i]);
+
+		if (spec->bit_offset % 8)
+			append_buf(" @ offset %u.%u)", spec->bit_offset / 8, spec->bit_offset % 8);
+		else
+			append_buf(" @ offset %u)", spec->bit_offset / 8);
+		return len;
+	}
+
+	return len;
+#undef append_buf
+}
+
+/*
+ * Calculate CO-RE relocation target result.
+ *
+ * The outline and important points of the algorithm:
+ * 1. For given local type, find corresponding candidate target types.
+ *    Candidate type is a type with the same "essential" name, ignoring
+ *    everything after last triple underscore (___). E.g., `sample`,
+ *    `sample___flavor_one`, `sample___flavor_another_one`, are all candidates
+ *    for each other. Names with triple underscore are referred to as
+ *    "flavors" and are useful, among other things, to allow to
+ *    specify/support incompatible variations of the same kernel struct, which
+ *    might differ between different kernel versions and/or build
+ *    configurations.
+ *
+ *    N.B. Struct "flavors" could be generated by bpftool's BTF-to-C
+ *    converter, when deduplicated BTF of a kernel still contains more than
+ *    one different types with the same name. In that case, ___2, ___3, etc
+ *    are appended starting from second name conflict. But start flavors are
+ *    also useful to be defined "locally", in BPF program, to extract same
+ *    data from incompatible changes between different kernel
+ *    versions/configurations. For instance, to handle field renames between
+ *    kernel versions, one can use two flavors of the struct name with the
+ *    same common name and use conditional relocations to extract that field,
+ *    depending on target kernel version.
+ * 2. For each candidate type, try to match local specification to this
+ *    candidate target type. Matching involves finding corresponding
+ *    high-level spec accessors, meaning that all named fields should match,
+ *    as well as all array accesses should be within the actual bounds. Also,
+ *    types should be compatible (see bpf_core_fields_are_compat for details).
+ * 3. It is supported and expected that there might be multiple flavors
+ *    matching the spec. As long as all the specs resolve to the same set of
+ *    offsets across all candidates, there is no error. If there is any
+ *    ambiguity, CO-RE relocation will fail. This is necessary to accommodate
+ *    imperfection of BTF deduplication, which can cause slight duplication of
+ *    the same BTF type, if some directly or indirectly referenced (by
+ *    pointer) type gets resolved to different actual types in different
+ *    object files. If such a situation occurs, deduplicated BTF will end up
+ *    with two (or more) structurally identical types, which differ only in
+ *    types they refer to through pointer. This should be OK in most cases and
+ *    is not an error.
+ * 4. Candidate types search is performed by linearly scanning through all
+ *    types in target BTF. It is anticipated that this is overall more
+ *    efficient memory-wise and not significantly worse (if not better)
+ *    CPU-wise compared to prebuilding a map from all local type names to
+ *    a list of candidate type names. It's also sped up by caching resolved
+ *    list of matching candidates per each local "root" type ID, that has at
+ *    least one bpf_core_relo associated with it. This list is shared
+ *    between multiple relocations for the same type ID and is updated as some
+ *    of the candidates are pruned due to structural incompatibility.
+ */
+int bpf_core_calc_relo_insn(const char *prog_name,
+			    const struct bpf_core_relo *relo,
+			    int relo_idx,
+			    const struct btf *local_btf,
+			    struct bpf_core_cand_list *cands,
+			    struct bpf_core_spec *specs_scratch,
+			    struct bpf_core_relo_res *targ_res)
+{
+	struct bpf_core_spec *local_spec = &specs_scratch[0];
+	struct bpf_core_spec *cand_spec = &specs_scratch[1];
+	struct bpf_core_spec *targ_spec = &specs_scratch[2];
+	struct bpf_core_relo_res cand_res;
+	const struct btf_type *local_type;
+	const char *local_name;
+	__u32 local_id;
+	char spec_buf[256];
+	int i, j, err;
+
+	local_id = relo->type_id;
+	local_type = btf_type_by_id(local_btf, local_id);
+	local_name = btf__name_by_offset(local_btf, local_type->name_off);
+	if (!local_name)
+		return -EINVAL;
+
+	err = bpf_core_parse_spec(prog_name, local_btf, relo, local_spec);
+	if (err) {
+		const char *spec_str;
+
+		spec_str = btf__name_by_offset(local_btf, relo->access_str_off);
+		pr_warn("prog '%s': relo #%d: parsing [%d] %s %s + %s failed: %d\n",
+			prog_name, relo_idx, local_id, btf_kind_str(local_type),
+			str_is_empty(local_name) ? "<anon>" : local_name,
+			spec_str ?: "<?>", err);
+		return -EINVAL;
+	}
+
+	bpf_core_format_spec(spec_buf, sizeof(spec_buf), local_spec);
+	pr_debug("prog '%s': relo #%d: %s\n", prog_name, relo_idx, spec_buf);
+
+	/* TYPE_ID_LOCAL relo is special and doesn't need candidate search */
+	if (relo->kind == BPF_CORE_TYPE_ID_LOCAL) {
+		/* bpf_insn's imm value could get out of sync during linking */
+		memset(targ_res, 0, sizeof(*targ_res));
+		targ_res->validate = false;
+		targ_res->poison = false;
+		targ_res->orig_val = local_spec->root_type_id;
+		targ_res->new_val = local_spec->root_type_id;
+		return 0;
+	}
+
+	/* libbpf doesn't support candidate search for anonymous types */
+	if (str_is_empty(local_name)) {
+		pr_warn("prog '%s': relo #%d: <%s> (%d) relocation doesn't support anonymous types\n",
+			prog_name, relo_idx, core_relo_kind_str(relo->kind), relo->kind);
+		return -EOPNOTSUPP;
+	}
+
+	for (i = 0, j = 0; i < cands->len; i++) {
+		err = bpf_core_spec_match(local_spec, cands->cands[i].btf,
+					  cands->cands[i].id, cand_spec);
+		if (err < 0) {
+			bpf_core_format_spec(spec_buf, sizeof(spec_buf), cand_spec);
+			pr_warn("prog '%s': relo #%d: error matching candidate #%d %s: %d\n ",
+				prog_name, relo_idx, i, spec_buf, err);
+			return err;
+		}
+
+		bpf_core_format_spec(spec_buf, sizeof(spec_buf), cand_spec);
+		pr_debug("prog '%s': relo #%d: %s candidate #%d %s\n", prog_name,
+			 relo_idx, err == 0 ? "non-matching" : "matching", i, spec_buf);
+
+		if (err == 0)
+			continue;
+
+		err = bpf_core_calc_relo(prog_name, relo, relo_idx, local_spec, cand_spec, &cand_res);
+		if (err)
+			return err;
+
+		if (j == 0) {
+			*targ_res = cand_res;
+			*targ_spec = *cand_spec;
+		} else if (cand_spec->bit_offset != targ_spec->bit_offset) {
+			/* if there are many field relo candidates, they
+			 * should all resolve to the same bit offset
+			 */
+			pr_warn("prog '%s': relo #%d: field offset ambiguity: %u != %u\n",
+				prog_name, relo_idx, cand_spec->bit_offset,
+				targ_spec->bit_offset);
+			return -EINVAL;
+		} else if (cand_res.poison != targ_res->poison ||
+			   cand_res.new_val != targ_res->new_val) {
+			/* all candidates should result in the same relocation
+			 * decision and value, otherwise it's dangerous to
+			 * proceed due to ambiguity
+			 */
+			pr_warn("prog '%s': relo #%d: relocation decision ambiguity: %s %llu != %s %llu\n",
+				prog_name, relo_idx,
+				cand_res.poison ? "failure" : "success",
+				(unsigned long long)cand_res.new_val,
+				targ_res->poison ? "failure" : "success",
+				(unsigned long long)targ_res->new_val);
+			return -EINVAL;
+		}
+
+		cands->cands[j++] = cands->cands[i];
+	}
+
+	/*
+	 * For BPF_CORE_FIELD_EXISTS relo or when used BPF program has field
+	 * existence checks or kernel version/config checks, it's expected
+	 * that we might not find any candidates. In this case, if field
+	 * wasn't found in any candidate, the list of candidates shouldn't
+	 * change at all, we'll just handle relocating appropriately,
+	 * depending on relo's kind.
+	 */
+	if (j > 0)
+		cands->len = j;
+
+	/*
+	 * If no candidates were found, it might be both a programmer error,
+	 * as well as expected case, depending whether instruction w/
+	 * relocation is guarded in some way that makes it unreachable (dead
+	 * code) if relocation can't be resolved. This is handled in
+	 * bpf_core_patch_insn() uniformly by replacing that instruction with
+	 * BPF helper call insn (using invalid helper ID). If that instruction
+	 * is indeed unreachable, then it will be ignored and eliminated by
+	 * verifier. If it was an error, then verifier will complain and point
+	 * to a specific instruction number in its log.
+	 */
+	if (j == 0) {
+		pr_debug("prog '%s': relo #%d: no matching targets found\n",
+			 prog_name, relo_idx);
+
+		/* calculate single target relo result explicitly */
+		err = bpf_core_calc_relo(prog_name, relo, relo_idx, local_spec, NULL, targ_res);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static bool bpf_core_names_match(const struct btf *local_btf, size_t local_name_off,
+				 const struct btf *targ_btf, size_t targ_name_off)
+{
+	const char *local_n, *targ_n;
+	size_t local_len, targ_len;
+
+	local_n = btf__name_by_offset(local_btf, local_name_off);
+	targ_n = btf__name_by_offset(targ_btf, targ_name_off);
+
+	if (str_is_empty(targ_n))
+		return str_is_empty(local_n);
+
+	targ_len = bpf_core_essential_name_len(targ_n);
+	local_len = bpf_core_essential_name_len(local_n);
+
+	return targ_len == local_len && strncmp(local_n, targ_n, local_len) == 0;
+}
+
+static int bpf_core_enums_match(const struct btf *local_btf, const struct btf_type *local_t,
+				const struct btf *targ_btf, const struct btf_type *targ_t)
+{
+	__u16 local_vlen = btf_vlen(local_t);
+	__u16 targ_vlen = btf_vlen(targ_t);
+	int i, j;
+
+	if (local_t->size != targ_t->size)
+		return 0;
+
+	if (local_vlen > targ_vlen)
+		return 0;
+
+	/* iterate over the local enum's variants and make sure each has
+	 * a symbolic name correspondent in the target
+	 */
+	for (i = 0; i < local_vlen; i++) {
+		bool matched = false;
+		__u32 local_n_off, targ_n_off;
+
+		local_n_off = btf_is_enum(local_t) ? btf_enum(local_t)[i].name_off :
+						     btf_enum64(local_t)[i].name_off;
+
+		for (j = 0; j < targ_vlen; j++) {
+			targ_n_off = btf_is_enum(targ_t) ? btf_enum(targ_t)[j].name_off :
+							   btf_enum64(targ_t)[j].name_off;
+
+			if (bpf_core_names_match(local_btf, local_n_off, targ_btf, targ_n_off)) {
+				matched = true;
+				break;
+			}
+		}
+
+		if (!matched)
+			return 0;
+	}
+	return 1;
+}
+
+static int bpf_core_composites_match(const struct btf *local_btf, const struct btf_type *local_t,
+				     const struct btf *targ_btf, const struct btf_type *targ_t,
+				     bool behind_ptr, int level)
+{
+	const struct btf_member *local_m = btf_members(local_t);
+	__u16 local_vlen = btf_vlen(local_t);
+	__u16 targ_vlen = btf_vlen(targ_t);
+	int i, j, err;
+
+	if (local_vlen > targ_vlen)
+		return 0;
+
+	/* check that all local members have a match in the target */
+	for (i = 0; i < local_vlen; i++, local_m++) {
+		const struct btf_member *targ_m = btf_members(targ_t);
+		bool matched = false;
+
+		for (j = 0; j < targ_vlen; j++, targ_m++) {
+			if (!bpf_core_names_match(local_btf, local_m->name_off,
+						  targ_btf, targ_m->name_off))
+				continue;
+
+			err = __bpf_core_types_match(local_btf, local_m->type, targ_btf,
+						     targ_m->type, behind_ptr, level - 1);
+			if (err < 0)
+				return err;
+			if (err > 0) {
+				matched = true;
+				break;
+			}
+		}
+
+		if (!matched)
+			return 0;
+	}
+	return 1;
+}
+
+/* Check that two types "match". This function assumes that root types were
+ * already checked for name match.
+ *
+ * The matching relation is defined as follows:
+ * - modifiers and typedefs are stripped (and, hence, effectively ignored)
+ * - generally speaking types need to be of same kind (struct vs. struct, union
+ *   vs. union, etc.)
+ *   - exceptions are struct/union behind a pointer which could also match a
+ *     forward declaration of a struct or union, respectively, and enum vs.
+ *     enum64 (see below)
+ * Then, depending on type:
+ * - integers:
+ *   - match if size and signedness match
+ * - arrays & pointers:
+ *   - target types are recursively matched
+ * - structs & unions:
+ *   - local members need to exist in target with the same name
+ *   - for each member we recursively check match unless it is already behind a
+ *     pointer, in which case we only check matching names and compatible kind
+ * - enums:
+ *   - local variants have to have a match in target by symbolic name (but not
+ *     numeric value)
+ *   - size has to match (but enum may match enum64 and vice versa)
+ * - function pointers:
+ *   - number and position of arguments in local type has to match target
+ *   - for each argument and the return value we recursively check match
+ */
+int __bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
+			   __u32 targ_id, bool behind_ptr, int level)
+{
+	const struct btf_type *local_t, *targ_t;
+	int depth = 32; /* max recursion depth */
+	__u16 local_k, targ_k;
+
+	if (level <= 0)
+		return -EINVAL;
+
+	local_t = btf_type_by_id(local_btf, local_id);
+	targ_t = btf_type_by_id(targ_btf, targ_id);
+
+recur:
+	depth--;
+	if (depth < 0)
+		return -EINVAL;
+
+	local_t = skip_mods_and_typedefs(local_btf, local_id, &local_id);
+	targ_t = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
+	if (!local_t || !targ_t)
+		return -EINVAL;
+
+	/* While the name check happens after typedefs are skipped, root-level
+	 * typedefs would still be name-matched as that's the contract with
+	 * callers.
+	 */
+	if (!bpf_core_names_match(local_btf, local_t->name_off, targ_btf, targ_t->name_off))
+		return 0;
+
+	local_k = btf_kind(local_t);
+	targ_k = btf_kind(targ_t);
+
+	switch (local_k) {
+	case BTF_KIND_UNKN:
+		return local_k == targ_k;
+	case BTF_KIND_FWD: {
+		bool local_f = BTF_INFO_KFLAG(local_t->info);
+
+		if (behind_ptr) {
+			if (local_k == targ_k)
+				return local_f == BTF_INFO_KFLAG(targ_t->info);
+
+			/* for forward declarations kflag dictates whether the
+			 * target is a struct (0) or union (1)
+			 */
+			return (targ_k == BTF_KIND_STRUCT && !local_f) ||
+			       (targ_k == BTF_KIND_UNION && local_f);
+		} else {
+			if (local_k != targ_k)
+				return 0;
+
+			/* match if the forward declaration is for the same kind */
+			return local_f == BTF_INFO_KFLAG(targ_t->info);
+		}
+	}
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		if (!btf_is_any_enum(targ_t))
+			return 0;
+
+		return bpf_core_enums_match(local_btf, local_t, targ_btf, targ_t);
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+		if (behind_ptr) {
+			bool targ_f = BTF_INFO_KFLAG(targ_t->info);
+
+			if (local_k == targ_k)
+				return 1;
+
+			if (targ_k != BTF_KIND_FWD)
+				return 0;
+
+			return (local_k == BTF_KIND_UNION) == targ_f;
+		} else {
+			if (local_k != targ_k)
+				return 0;
+
+			return bpf_core_composites_match(local_btf, local_t, targ_btf, targ_t,
+							 behind_ptr, level);
+		}
+	case BTF_KIND_INT: {
+		__u8 local_sgn;
+		__u8 targ_sgn;
+
+		if (local_k != targ_k)
+			return 0;
+
+		local_sgn = btf_int_encoding(local_t) & BTF_INT_SIGNED;
+		targ_sgn = btf_int_encoding(targ_t) & BTF_INT_SIGNED;
+
+		return local_t->size == targ_t->size && local_sgn == targ_sgn;
+	}
+	case BTF_KIND_PTR:
+		if (local_k != targ_k)
+			return 0;
+
+		behind_ptr = true;
+
+		local_id = local_t->type;
+		targ_id = targ_t->type;
+		goto recur;
+	case BTF_KIND_ARRAY: {
+		const struct btf_array *local_array = btf_array(local_t);
+		const struct btf_array *targ_array = btf_array(targ_t);
+
+		if (local_k != targ_k)
+			return 0;
+
+		if (local_array->nelems != targ_array->nelems)
+			return 0;
+
+		local_id = local_array->type;
+		targ_id = targ_array->type;
+		goto recur;
+	}
+	case BTF_KIND_FUNC_PROTO: {
+		struct btf_param *local_p = btf_params(local_t);
+		struct btf_param *targ_p = btf_params(targ_t);
+		__u16 local_vlen = btf_vlen(local_t);
+		__u16 targ_vlen = btf_vlen(targ_t);
+		int i, err;
+
+		if (local_k != targ_k)
+			return 0;
+
+		if (local_vlen != targ_vlen)
+			return 0;
+
+		for (i = 0; i < local_vlen; i++, local_p++, targ_p++) {
+			err = __bpf_core_types_match(local_btf, local_p->type, targ_btf,
+						     targ_p->type, behind_ptr, level - 1);
+			if (err <= 0)
+				return err;
+		}
+
+		/* tail recurse for return type check */
+		local_id = local_t->type;
+		targ_id = targ_t->type;
+		goto recur;
+	}
+	default:
+		pr_warn("unexpected kind %s relocated, local [%d], target [%d]\n",
+			btf_kind_str(local_t), local_id, targ_id);
+		return 0;
+	}
+}
diff --git a/src/relo_core.h b/src/relo_core.h
new file mode 100644
index 0000000..1c0566d
--- /dev/null
+++ b/src/relo_core.h
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/* Copyright (c) 2019 Facebook */
+
+#ifndef __RELO_CORE_H
+#define __RELO_CORE_H
+
+#include <linux/bpf.h>
+
+struct bpf_core_cand {
+	const struct btf *btf;
+	__u32 id;
+};
+
+/* dynamically sized list of type IDs and its associated struct btf */
+struct bpf_core_cand_list {
+	struct bpf_core_cand *cands;
+	int len;
+};
+
+#define BPF_CORE_SPEC_MAX_LEN 64
+
+/* represents BPF CO-RE field or array element accessor */
+struct bpf_core_accessor {
+	__u32 type_id;		/* struct/union type or array element type */
+	__u32 idx;		/* field index or array index */
+	const char *name;	/* field name or NULL for array accessor */
+};
+
+struct bpf_core_spec {
+	const struct btf *btf;
+	/* high-level spec: named fields and array indices only */
+	struct bpf_core_accessor spec[BPF_CORE_SPEC_MAX_LEN];
+	/* original unresolved (no skip_mods_or_typedefs) root type ID */
+	__u32 root_type_id;
+	/* CO-RE relocation kind */
+	enum bpf_core_relo_kind relo_kind;
+	/* high-level spec length */
+	int len;
+	/* raw, low-level spec: 1-to-1 with accessor spec string */
+	int raw_spec[BPF_CORE_SPEC_MAX_LEN];
+	/* raw spec length */
+	int raw_len;
+	/* field bit offset represented by spec */
+	__u32 bit_offset;
+};
+
+struct bpf_core_relo_res {
+	/* expected value in the instruction, unless validate == false */
+	__u64 orig_val;
+	/* new value that needs to be patched up to */
+	__u64 new_val;
+	/* relocation unsuccessful, poison instruction, but don't fail load */
+	bool poison;
+	/* some relocations can't be validated against orig_val */
+	bool validate;
+	/* for field byte offset relocations or the forms:
+	 *     *(T *)(rX + <off>) = rY
+	 *     rX = *(T *)(rY + <off>),
+	 * we remember original and resolved field size to adjust direct
+	 * memory loads of pointers and integers; this is necessary for 32-bit
+	 * host kernel architectures, but also allows to automatically
+	 * relocate fields that were resized from, e.g., u32 to u64, etc.
+	 */
+	bool fail_memsz_adjust;
+	__u32 orig_sz;
+	__u32 orig_type_id;
+	__u32 new_sz;
+	__u32 new_type_id;
+};
+
+int __bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
+				const struct btf *targ_btf, __u32 targ_id, int level);
+int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
+			      const struct btf *targ_btf, __u32 targ_id);
+int __bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
+			   __u32 targ_id, bool behind_ptr, int level);
+int bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
+			 __u32 targ_id);
+
+size_t bpf_core_essential_name_len(const char *name);
+
+int bpf_core_calc_relo_insn(const char *prog_name,
+			    const struct bpf_core_relo *relo, int relo_idx,
+			    const struct btf *local_btf,
+			    struct bpf_core_cand_list *cands,
+			    struct bpf_core_spec *specs_scratch,
+			    struct bpf_core_relo_res *targ_res);
+
+int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn,
+			int insn_idx, const struct bpf_core_relo *relo,
+			int relo_idx, const struct bpf_core_relo_res *res);
+
+int bpf_core_parse_spec(const char *prog_name, const struct btf *btf,
+		        const struct bpf_core_relo *relo,
+		        struct bpf_core_spec *spec);
+
+int bpf_core_format_spec(char *buf, size_t buf_sz, const struct bpf_core_spec *spec);
+
+#endif
diff --git a/src/ringbuf.c b/src/ringbuf.c
new file mode 100644
index 0000000..47855af
--- /dev/null
+++ b/src/ringbuf.c
@@ -0,0 +1,587 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/*
+ * Ring buffer operations.
+ *
+ * Copyright (C) 2020 Facebook, Inc.
+ */
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <linux/err.h>
+#include <linux/bpf.h>
+#include <asm/barrier.h>
+#include <sys/mman.h>
+#include <sys/epoll.h>
+#include <time.h>
+
+#include "libbpf.h"
+#include "libbpf_internal.h"
+#include "bpf.h"
+
+struct ring {
+	ring_buffer_sample_fn sample_cb;
+	void *ctx;
+	void *data;
+	unsigned long *consumer_pos;
+	unsigned long *producer_pos;
+	unsigned long mask;
+	int map_fd;
+};
+
+struct ring_buffer {
+	struct epoll_event *events;
+	struct ring *rings;
+	size_t page_size;
+	int epoll_fd;
+	int ring_cnt;
+};
+
+struct user_ring_buffer {
+	struct epoll_event event;
+	unsigned long *consumer_pos;
+	unsigned long *producer_pos;
+	void *data;
+	unsigned long mask;
+	size_t page_size;
+	int map_fd;
+	int epoll_fd;
+};
+
+/* 8-byte ring buffer header structure */
+struct ringbuf_hdr {
+	__u32 len;
+	__u32 pad;
+};
+
+static void ringbuf_unmap_ring(struct ring_buffer *rb, struct ring *r)
+{
+	if (r->consumer_pos) {
+		munmap(r->consumer_pos, rb->page_size);
+		r->consumer_pos = NULL;
+	}
+	if (r->producer_pos) {
+		munmap(r->producer_pos, rb->page_size + 2 * (r->mask + 1));
+		r->producer_pos = NULL;
+	}
+}
+
+/* Add extra RINGBUF maps to this ring buffer manager */
+int ring_buffer__add(struct ring_buffer *rb, int map_fd,
+		     ring_buffer_sample_fn sample_cb, void *ctx)
+{
+	struct bpf_map_info info;
+	__u32 len = sizeof(info);
+	struct epoll_event *e;
+	struct ring *r;
+	__u64 mmap_sz;
+	void *tmp;
+	int err;
+
+	memset(&info, 0, sizeof(info));
+
+	err = bpf_obj_get_info_by_fd(map_fd, &info, &len);
+	if (err) {
+		err = -errno;
+		pr_warn("ringbuf: failed to get map info for fd=%d: %d\n",
+			map_fd, err);
+		return libbpf_err(err);
+	}
+
+	if (info.type != BPF_MAP_TYPE_RINGBUF) {
+		pr_warn("ringbuf: map fd=%d is not BPF_MAP_TYPE_RINGBUF\n",
+			map_fd);
+		return libbpf_err(-EINVAL);
+	}
+
+	tmp = libbpf_reallocarray(rb->rings, rb->ring_cnt + 1, sizeof(*rb->rings));
+	if (!tmp)
+		return libbpf_err(-ENOMEM);
+	rb->rings = tmp;
+
+	tmp = libbpf_reallocarray(rb->events, rb->ring_cnt + 1, sizeof(*rb->events));
+	if (!tmp)
+		return libbpf_err(-ENOMEM);
+	rb->events = tmp;
+
+	r = &rb->rings[rb->ring_cnt];
+	memset(r, 0, sizeof(*r));
+
+	r->map_fd = map_fd;
+	r->sample_cb = sample_cb;
+	r->ctx = ctx;
+	r->mask = info.max_entries - 1;
+
+	/* Map writable consumer page */
+	tmp = mmap(NULL, rb->page_size, PROT_READ | PROT_WRITE, MAP_SHARED, map_fd, 0);
+	if (tmp == MAP_FAILED) {
+		err = -errno;
+		pr_warn("ringbuf: failed to mmap consumer page for map fd=%d: %d\n",
+			map_fd, err);
+		return libbpf_err(err);
+	}
+	r->consumer_pos = tmp;
+
+	/* Map read-only producer page and data pages. We map twice as big
+	 * data size to allow simple reading of samples that wrap around the
+	 * end of a ring buffer. See kernel implementation for details.
+	 */
+	mmap_sz = rb->page_size + 2 * (__u64)info.max_entries;
+	if (mmap_sz != (__u64)(size_t)mmap_sz) {
+		pr_warn("ringbuf: ring buffer size (%u) is too big\n", info.max_entries);
+		return libbpf_err(-E2BIG);
+	}
+	tmp = mmap(NULL, (size_t)mmap_sz, PROT_READ, MAP_SHARED, map_fd, rb->page_size);
+	if (tmp == MAP_FAILED) {
+		err = -errno;
+		ringbuf_unmap_ring(rb, r);
+		pr_warn("ringbuf: failed to mmap data pages for map fd=%d: %d\n",
+			map_fd, err);
+		return libbpf_err(err);
+	}
+	r->producer_pos = tmp;
+	r->data = tmp + rb->page_size;
+
+	e = &rb->events[rb->ring_cnt];
+	memset(e, 0, sizeof(*e));
+
+	e->events = EPOLLIN;
+	e->data.fd = rb->ring_cnt;
+	if (epoll_ctl(rb->epoll_fd, EPOLL_CTL_ADD, map_fd, e) < 0) {
+		err = -errno;
+		ringbuf_unmap_ring(rb, r);
+		pr_warn("ringbuf: failed to epoll add map fd=%d: %d\n",
+			map_fd, err);
+		return libbpf_err(err);
+	}
+
+	rb->ring_cnt++;
+	return 0;
+}
+
+void ring_buffer__free(struct ring_buffer *rb)
+{
+	int i;
+
+	if (!rb)
+		return;
+
+	for (i = 0; i < rb->ring_cnt; ++i)
+		ringbuf_unmap_ring(rb, &rb->rings[i]);
+	if (rb->epoll_fd >= 0)
+		close(rb->epoll_fd);
+
+	free(rb->events);
+	free(rb->rings);
+	free(rb);
+}
+
+struct ring_buffer *
+ring_buffer__new(int map_fd, ring_buffer_sample_fn sample_cb, void *ctx,
+		 const struct ring_buffer_opts *opts)
+{
+	struct ring_buffer *rb;
+	int err;
+
+	if (!OPTS_VALID(opts, ring_buffer_opts))
+		return errno = EINVAL, NULL;
+
+	rb = calloc(1, sizeof(*rb));
+	if (!rb)
+		return errno = ENOMEM, NULL;
+
+	rb->page_size = getpagesize();
+
+	rb->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
+	if (rb->epoll_fd < 0) {
+		err = -errno;
+		pr_warn("ringbuf: failed to create epoll instance: %d\n", err);
+		goto err_out;
+	}
+
+	err = ring_buffer__add(rb, map_fd, sample_cb, ctx);
+	if (err)
+		goto err_out;
+
+	return rb;
+
+err_out:
+	ring_buffer__free(rb);
+	return errno = -err, NULL;
+}
+
+static inline int roundup_len(__u32 len)
+{
+	/* clear out top 2 bits (discard and busy, if set) */
+	len <<= 2;
+	len >>= 2;
+	/* add length prefix */
+	len += BPF_RINGBUF_HDR_SZ;
+	/* round up to 8 byte alignment */
+	return (len + 7) / 8 * 8;
+}
+
+static int64_t ringbuf_process_ring(struct ring *r)
+{
+	int *len_ptr, len, err;
+	/* 64-bit to avoid overflow in case of extreme application behavior */
+	int64_t cnt = 0;
+	unsigned long cons_pos, prod_pos;
+	bool got_new_data;
+	void *sample;
+
+	cons_pos = smp_load_acquire(r->consumer_pos);
+	do {
+		got_new_data = false;
+		prod_pos = smp_load_acquire(r->producer_pos);
+		while (cons_pos < prod_pos) {
+			len_ptr = r->data + (cons_pos & r->mask);
+			len = smp_load_acquire(len_ptr);
+
+			/* sample not committed yet, bail out for now */
+			if (len & BPF_RINGBUF_BUSY_BIT)
+				goto done;
+
+			got_new_data = true;
+			cons_pos += roundup_len(len);
+
+			if ((len & BPF_RINGBUF_DISCARD_BIT) == 0) {
+				sample = (void *)len_ptr + BPF_RINGBUF_HDR_SZ;
+				err = r->sample_cb(r->ctx, sample, len);
+				if (err < 0) {
+					/* update consumer pos and bail out */
+					smp_store_release(r->consumer_pos,
+							  cons_pos);
+					return err;
+				}
+				cnt++;
+			}
+
+			smp_store_release(r->consumer_pos, cons_pos);
+		}
+	} while (got_new_data);
+done:
+	return cnt;
+}
+
+/* Consume available ring buffer(s) data without event polling.
+ * Returns number of records consumed across all registered ring buffers (or
+ * INT_MAX, whichever is less), or negative number if any of the callbacks
+ * return error.
+ */
+int ring_buffer__consume(struct ring_buffer *rb)
+{
+	int64_t err, res = 0;
+	int i;
+
+	for (i = 0; i < rb->ring_cnt; i++) {
+		struct ring *ring = &rb->rings[i];
+
+		err = ringbuf_process_ring(ring);
+		if (err < 0)
+			return libbpf_err(err);
+		res += err;
+	}
+	if (res > INT_MAX)
+		return INT_MAX;
+	return res;
+}
+
+/* Poll for available data and consume records, if any are available.
+ * Returns number of records consumed (or INT_MAX, whichever is less), or
+ * negative number, if any of the registered callbacks returned error.
+ */
+int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms)
+{
+	int i, cnt;
+	int64_t err, res = 0;
+
+	cnt = epoll_wait(rb->epoll_fd, rb->events, rb->ring_cnt, timeout_ms);
+	if (cnt < 0)
+		return libbpf_err(-errno);
+
+	for (i = 0; i < cnt; i++) {
+		__u32 ring_id = rb->events[i].data.fd;
+		struct ring *ring = &rb->rings[ring_id];
+
+		err = ringbuf_process_ring(ring);
+		if (err < 0)
+			return libbpf_err(err);
+		res += err;
+	}
+	if (res > INT_MAX)
+		return INT_MAX;
+	return res;
+}
+
+/* Get an fd that can be used to sleep until data is available in the ring(s) */
+int ring_buffer__epoll_fd(const struct ring_buffer *rb)
+{
+	return rb->epoll_fd;
+}
+
+static void user_ringbuf_unmap_ring(struct user_ring_buffer *rb)
+{
+	if (rb->consumer_pos) {
+		munmap(rb->consumer_pos, rb->page_size);
+		rb->consumer_pos = NULL;
+	}
+	if (rb->producer_pos) {
+		munmap(rb->producer_pos, rb->page_size + 2 * (rb->mask + 1));
+		rb->producer_pos = NULL;
+	}
+}
+
+void user_ring_buffer__free(struct user_ring_buffer *rb)
+{
+	if (!rb)
+		return;
+
+	user_ringbuf_unmap_ring(rb);
+
+	if (rb->epoll_fd >= 0)
+		close(rb->epoll_fd);
+
+	free(rb);
+}
+
+static int user_ringbuf_map(struct user_ring_buffer *rb, int map_fd)
+{
+	struct bpf_map_info info;
+	__u32 len = sizeof(info);
+	__u64 mmap_sz;
+	void *tmp;
+	struct epoll_event *rb_epoll;
+	int err;
+
+	memset(&info, 0, sizeof(info));
+
+	err = bpf_obj_get_info_by_fd(map_fd, &info, &len);
+	if (err) {
+		err = -errno;
+		pr_warn("user ringbuf: failed to get map info for fd=%d: %d\n", map_fd, err);
+		return err;
+	}
+
+	if (info.type != BPF_MAP_TYPE_USER_RINGBUF) {
+		pr_warn("user ringbuf: map fd=%d is not BPF_MAP_TYPE_USER_RINGBUF\n", map_fd);
+		return -EINVAL;
+	}
+
+	rb->map_fd = map_fd;
+	rb->mask = info.max_entries - 1;
+
+	/* Map read-only consumer page */
+	tmp = mmap(NULL, rb->page_size, PROT_READ, MAP_SHARED, map_fd, 0);
+	if (tmp == MAP_FAILED) {
+		err = -errno;
+		pr_warn("user ringbuf: failed to mmap consumer page for map fd=%d: %d\n",
+			map_fd, err);
+		return err;
+	}
+	rb->consumer_pos = tmp;
+
+	/* Map read-write the producer page and data pages. We map the data
+	 * region as twice the total size of the ring buffer to allow the
+	 * simple reading and writing of samples that wrap around the end of
+	 * the buffer.  See the kernel implementation for details.
+	 */
+	mmap_sz = rb->page_size + 2 * (__u64)info.max_entries;
+	if (mmap_sz != (__u64)(size_t)mmap_sz) {
+		pr_warn("user ringbuf: ring buf size (%u) is too big\n", info.max_entries);
+		return -E2BIG;
+	}
+	tmp = mmap(NULL, (size_t)mmap_sz, PROT_READ | PROT_WRITE, MAP_SHARED,
+		   map_fd, rb->page_size);
+	if (tmp == MAP_FAILED) {
+		err = -errno;
+		pr_warn("user ringbuf: failed to mmap data pages for map fd=%d: %d\n",
+			map_fd, err);
+		return err;
+	}
+
+	rb->producer_pos = tmp;
+	rb->data = tmp + rb->page_size;
+
+	rb_epoll = &rb->event;
+	rb_epoll->events = EPOLLOUT;
+	if (epoll_ctl(rb->epoll_fd, EPOLL_CTL_ADD, map_fd, rb_epoll) < 0) {
+		err = -errno;
+		pr_warn("user ringbuf: failed to epoll add map fd=%d: %d\n", map_fd, err);
+		return err;
+	}
+
+	return 0;
+}
+
+struct user_ring_buffer *
+user_ring_buffer__new(int map_fd, const struct user_ring_buffer_opts *opts)
+{
+	struct user_ring_buffer *rb;
+	int err;
+
+	if (!OPTS_VALID(opts, user_ring_buffer_opts))
+		return errno = EINVAL, NULL;
+
+	rb = calloc(1, sizeof(*rb));
+	if (!rb)
+		return errno = ENOMEM, NULL;
+
+	rb->page_size = getpagesize();
+
+	rb->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
+	if (rb->epoll_fd < 0) {
+		err = -errno;
+		pr_warn("user ringbuf: failed to create epoll instance: %d\n", err);
+		goto err_out;
+	}
+
+	err = user_ringbuf_map(rb, map_fd);
+	if (err)
+		goto err_out;
+
+	return rb;
+
+err_out:
+	user_ring_buffer__free(rb);
+	return errno = -err, NULL;
+}
+
+static void user_ringbuf_commit(struct user_ring_buffer *rb, void *sample, bool discard)
+{
+	__u32 new_len;
+	struct ringbuf_hdr *hdr;
+	uintptr_t hdr_offset;
+
+	hdr_offset = rb->mask + 1 + (sample - rb->data) - BPF_RINGBUF_HDR_SZ;
+	hdr = rb->data + (hdr_offset & rb->mask);
+
+	new_len = hdr->len & ~BPF_RINGBUF_BUSY_BIT;
+	if (discard)
+		new_len |= BPF_RINGBUF_DISCARD_BIT;
+
+	/* Synchronizes with smp_load_acquire() in __bpf_user_ringbuf_peek() in
+	 * the kernel.
+	 */
+	__atomic_exchange_n(&hdr->len, new_len, __ATOMIC_ACQ_REL);
+}
+
+void user_ring_buffer__discard(struct user_ring_buffer *rb, void *sample)
+{
+	user_ringbuf_commit(rb, sample, true);
+}
+
+void user_ring_buffer__submit(struct user_ring_buffer *rb, void *sample)
+{
+	user_ringbuf_commit(rb, sample, false);
+}
+
+void *user_ring_buffer__reserve(struct user_ring_buffer *rb, __u32 size)
+{
+	__u32 avail_size, total_size, max_size;
+	/* 64-bit to avoid overflow in case of extreme application behavior */
+	__u64 cons_pos, prod_pos;
+	struct ringbuf_hdr *hdr;
+
+	/* The top two bits are used as special flags */
+	if (size & (BPF_RINGBUF_BUSY_BIT | BPF_RINGBUF_DISCARD_BIT))
+		return errno = E2BIG, NULL;
+
+	/* Synchronizes with smp_store_release() in __bpf_user_ringbuf_peek() in
+	 * the kernel.
+	 */
+	cons_pos = smp_load_acquire(rb->consumer_pos);
+	/* Synchronizes with smp_store_release() in user_ringbuf_commit() */
+	prod_pos = smp_load_acquire(rb->producer_pos);
+
+	max_size = rb->mask + 1;
+	avail_size = max_size - (prod_pos - cons_pos);
+	/* Round up total size to a multiple of 8. */
+	total_size = (size + BPF_RINGBUF_HDR_SZ + 7) / 8 * 8;
+
+	if (total_size > max_size)
+		return errno = E2BIG, NULL;
+
+	if (avail_size < total_size)
+		return errno = ENOSPC, NULL;
+
+	hdr = rb->data + (prod_pos & rb->mask);
+	hdr->len = size | BPF_RINGBUF_BUSY_BIT;
+	hdr->pad = 0;
+
+	/* Synchronizes with smp_load_acquire() in __bpf_user_ringbuf_peek() in
+	 * the kernel.
+	 */
+	smp_store_release(rb->producer_pos, prod_pos + total_size);
+
+	return (void *)rb->data + ((prod_pos + BPF_RINGBUF_HDR_SZ) & rb->mask);
+}
+
+static __u64 ns_elapsed_timespec(const struct timespec *start, const struct timespec *end)
+{
+	__u64 start_ns, end_ns, ns_per_s = 1000000000;
+
+	start_ns = (__u64)start->tv_sec * ns_per_s + start->tv_nsec;
+	end_ns = (__u64)end->tv_sec * ns_per_s + end->tv_nsec;
+
+	return end_ns - start_ns;
+}
+
+void *user_ring_buffer__reserve_blocking(struct user_ring_buffer *rb, __u32 size, int timeout_ms)
+{
+	void *sample;
+	int err, ms_remaining = timeout_ms;
+	struct timespec start;
+
+	if (timeout_ms < 0 && timeout_ms != -1)
+		return errno = EINVAL, NULL;
+
+	if (timeout_ms != -1) {
+		err = clock_gettime(CLOCK_MONOTONIC, &start);
+		if (err)
+			return NULL;
+	}
+
+	do {
+		int cnt, ms_elapsed;
+		struct timespec curr;
+		__u64 ns_per_ms = 1000000;
+
+		sample = user_ring_buffer__reserve(rb, size);
+		if (sample)
+			return sample;
+		else if (errno != ENOSPC)
+			return NULL;
+
+		/* The kernel guarantees at least one event notification
+		 * delivery whenever at least one sample is drained from the
+		 * ring buffer in an invocation to bpf_ringbuf_drain(). Other
+		 * additional events may be delivered at any time, but only one
+		 * event is guaranteed per bpf_ringbuf_drain() invocation,
+		 * provided that a sample is drained, and the BPF program did
+		 * not pass BPF_RB_NO_WAKEUP to bpf_ringbuf_drain(). If
+		 * BPF_RB_FORCE_WAKEUP is passed to bpf_ringbuf_drain(), a
+		 * wakeup event will be delivered even if no samples are
+		 * drained.
+		 */
+		cnt = epoll_wait(rb->epoll_fd, &rb->event, 1, ms_remaining);
+		if (cnt < 0)
+			return NULL;
+
+		if (timeout_ms == -1)
+			continue;
+
+		err = clock_gettime(CLOCK_MONOTONIC, &curr);
+		if (err)
+			return NULL;
+
+		ms_elapsed = ns_elapsed_timespec(&start, &curr) / ns_per_ms;
+		ms_remaining = timeout_ms - ms_elapsed;
+	} while (ms_remaining > 0);
+
+	/* Try one more time to reserve a sample after the specified timeout has elapsed. */
+	return user_ring_buffer__reserve(rb, size);
+}
diff --git a/src/skel_internal.h b/src/skel_internal.h
new file mode 100644
index 0000000..1e82ab0
--- /dev/null
+++ b/src/skel_internal.h
@@ -0,0 +1,374 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/* Copyright (c) 2021 Facebook */
+#ifndef __SKEL_INTERNAL_H
+#define __SKEL_INTERNAL_H
+
+#ifdef __KERNEL__
+#include <linux/fdtable.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/slab.h>
+#include <linux/bpf.h>
+#else
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <sys/mman.h>
+#include <stdlib.h>
+#include "bpf.h"
+#endif
+
+#ifndef __NR_bpf
+# if defined(__mips__) && defined(_ABIO32)
+#  define __NR_bpf 4355
+# elif defined(__mips__) && defined(_ABIN32)
+#  define __NR_bpf 6319
+# elif defined(__mips__) && defined(_ABI64)
+#  define __NR_bpf 5315
+# endif
+#endif
+
+/* This file is a base header for auto-generated *.lskel.h files.
+ * Its contents will change and may become part of auto-generation in the future.
+ *
+ * The layout of bpf_[map|prog]_desc and bpf_loader_ctx is feature dependent
+ * and will change from one version of libbpf to another and features
+ * requested during loader program generation.
+ */
+struct bpf_map_desc {
+	/* output of the loader prog */
+	int map_fd;
+	/* input for the loader prog */
+	__u32 max_entries;
+	__aligned_u64 initial_value;
+};
+struct bpf_prog_desc {
+	int prog_fd;
+};
+
+enum {
+	BPF_SKEL_KERNEL = (1ULL << 0),
+};
+
+struct bpf_loader_ctx {
+	__u32 sz;
+	__u32 flags;
+	__u32 log_level;
+	__u32 log_size;
+	__u64 log_buf;
+};
+
+struct bpf_load_and_run_opts {
+	struct bpf_loader_ctx *ctx;
+	const void *data;
+	const void *insns;
+	__u32 data_sz;
+	__u32 insns_sz;
+	const char *errstr;
+};
+
+long kern_sys_bpf(__u32 cmd, void *attr, __u32 attr_size);
+
+static inline int skel_sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr,
+			  unsigned int size)
+{
+#ifdef __KERNEL__
+	return kern_sys_bpf(cmd, attr, size);
+#else
+	return syscall(__NR_bpf, cmd, attr, size);
+#endif
+}
+
+#ifdef __KERNEL__
+static inline int close(int fd)
+{
+	return close_fd(fd);
+}
+
+static inline void *skel_alloc(size_t size)
+{
+	struct bpf_loader_ctx *ctx = kzalloc(size, GFP_KERNEL);
+
+	if (!ctx)
+		return NULL;
+	ctx->flags |= BPF_SKEL_KERNEL;
+	return ctx;
+}
+
+static inline void skel_free(const void *p)
+{
+	kfree(p);
+}
+
+/* skel->bss/rodata maps are populated the following way:
+ *
+ * For kernel use:
+ * skel_prep_map_data() allocates kernel memory that kernel module can directly access.
+ * Generated lskel stores the pointer in skel->rodata and in skel->maps.rodata.initial_value.
+ * The loader program will perform probe_read_kernel() from maps.rodata.initial_value.
+ * skel_finalize_map_data() sets skel->rodata to point to actual value in a bpf map and
+ * does maps.rodata.initial_value = ~0ULL to signal skel_free_map_data() that kvfree
+ * is not nessary.
+ *
+ * For user space:
+ * skel_prep_map_data() mmaps anon memory into skel->rodata that can be accessed directly.
+ * Generated lskel stores the pointer in skel->rodata and in skel->maps.rodata.initial_value.
+ * The loader program will perform copy_from_user() from maps.rodata.initial_value.
+ * skel_finalize_map_data() remaps bpf array map value from the kernel memory into
+ * skel->rodata address.
+ *
+ * The "bpftool gen skeleton -L" command generates lskel.h that is suitable for
+ * both kernel and user space. The generated loader program does
+ * either bpf_probe_read_kernel() or bpf_copy_from_user() from initial_value
+ * depending on bpf_loader_ctx->flags.
+ */
+static inline void skel_free_map_data(void *p, __u64 addr, size_t sz)
+{
+	if (addr != ~0ULL)
+		kvfree(p);
+	/* When addr == ~0ULL the 'p' points to
+	 * ((struct bpf_array *)map)->value. See skel_finalize_map_data.
+	 */
+}
+
+static inline void *skel_prep_map_data(const void *val, size_t mmap_sz, size_t val_sz)
+{
+	void *addr;
+
+	addr = kvmalloc(val_sz, GFP_KERNEL);
+	if (!addr)
+		return NULL;
+	memcpy(addr, val, val_sz);
+	return addr;
+}
+
+static inline void *skel_finalize_map_data(__u64 *init_val, size_t mmap_sz, int flags, int fd)
+{
+	struct bpf_map *map;
+	void *addr = NULL;
+
+	kvfree((void *) (long) *init_val);
+	*init_val = ~0ULL;
+
+	/* At this point bpf_load_and_run() finished without error and
+	 * 'fd' is a valid bpf map FD. All sanity checks below should succeed.
+	 */
+	map = bpf_map_get(fd);
+	if (IS_ERR(map))
+		return NULL;
+	if (map->map_type != BPF_MAP_TYPE_ARRAY)
+		goto out;
+	addr = ((struct bpf_array *)map)->value;
+	/* the addr stays valid, since FD is not closed */
+out:
+	bpf_map_put(map);
+	return addr;
+}
+
+#else
+
+static inline void *skel_alloc(size_t size)
+{
+	return calloc(1, size);
+}
+
+static inline void skel_free(void *p)
+{
+	free(p);
+}
+
+static inline void skel_free_map_data(void *p, __u64 addr, size_t sz)
+{
+	munmap(p, sz);
+}
+
+static inline void *skel_prep_map_data(const void *val, size_t mmap_sz, size_t val_sz)
+{
+	void *addr;
+
+	addr = mmap(NULL, mmap_sz, PROT_READ | PROT_WRITE,
+		    MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+	if (addr == (void *) -1)
+		return NULL;
+	memcpy(addr, val, val_sz);
+	return addr;
+}
+
+static inline void *skel_finalize_map_data(__u64 *init_val, size_t mmap_sz, int flags, int fd)
+{
+	void *addr;
+
+	addr = mmap((void *) (long) *init_val, mmap_sz, flags, MAP_SHARED | MAP_FIXED, fd, 0);
+	if (addr == (void *) -1)
+		return NULL;
+	return addr;
+}
+#endif
+
+static inline int skel_closenz(int fd)
+{
+	if (fd > 0)
+		return close(fd);
+	return -EINVAL;
+}
+
+#ifndef offsetofend
+#define offsetofend(TYPE, MEMBER) \
+	(offsetof(TYPE, MEMBER)	+ sizeof((((TYPE *)0)->MEMBER)))
+#endif
+
+static inline int skel_map_create(enum bpf_map_type map_type,
+				  const char *map_name,
+				  __u32 key_size,
+				  __u32 value_size,
+				  __u32 max_entries)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, map_extra);
+	union bpf_attr attr;
+
+	memset(&attr, 0, attr_sz);
+
+	attr.map_type = map_type;
+	strncpy(attr.map_name, map_name, sizeof(attr.map_name));
+	attr.key_size = key_size;
+	attr.value_size = value_size;
+	attr.max_entries = max_entries;
+
+	return skel_sys_bpf(BPF_MAP_CREATE, &attr, attr_sz);
+}
+
+static inline int skel_map_update_elem(int fd, const void *key,
+				       const void *value, __u64 flags)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
+	union bpf_attr attr;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_fd = fd;
+	attr.key = (long) key;
+	attr.value = (long) value;
+	attr.flags = flags;
+
+	return skel_sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, attr_sz);
+}
+
+static inline int skel_map_delete_elem(int fd, const void *key)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
+	union bpf_attr attr;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_fd = fd;
+	attr.key = (long)key;
+
+	return skel_sys_bpf(BPF_MAP_DELETE_ELEM, &attr, attr_sz);
+}
+
+static inline int skel_map_get_fd_by_id(__u32 id)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
+	union bpf_attr attr;
+
+	memset(&attr, 0, attr_sz);
+	attr.map_id = id;
+
+	return skel_sys_bpf(BPF_MAP_GET_FD_BY_ID, &attr, attr_sz);
+}
+
+static inline int skel_raw_tracepoint_open(const char *name, int prog_fd)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, raw_tracepoint.prog_fd);
+	union bpf_attr attr;
+
+	memset(&attr, 0, attr_sz);
+	attr.raw_tracepoint.name = (long) name;
+	attr.raw_tracepoint.prog_fd = prog_fd;
+
+	return skel_sys_bpf(BPF_RAW_TRACEPOINT_OPEN, &attr, attr_sz);
+}
+
+static inline int skel_link_create(int prog_fd, int target_fd,
+				   enum bpf_attach_type attach_type)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, link_create.iter_info_len);
+	union bpf_attr attr;
+
+	memset(&attr, 0, attr_sz);
+	attr.link_create.prog_fd = prog_fd;
+	attr.link_create.target_fd = target_fd;
+	attr.link_create.attach_type = attach_type;
+
+	return skel_sys_bpf(BPF_LINK_CREATE, &attr, attr_sz);
+}
+
+#ifdef __KERNEL__
+#define set_err
+#else
+#define set_err err = -errno
+#endif
+
+static inline int bpf_load_and_run(struct bpf_load_and_run_opts *opts)
+{
+	const size_t prog_load_attr_sz = offsetofend(union bpf_attr, fd_array);
+	const size_t test_run_attr_sz = offsetofend(union bpf_attr, test);
+	int map_fd = -1, prog_fd = -1, key = 0, err;
+	union bpf_attr attr;
+
+	err = map_fd = skel_map_create(BPF_MAP_TYPE_ARRAY, "__loader.map", 4, opts->data_sz, 1);
+	if (map_fd < 0) {
+		opts->errstr = "failed to create loader map";
+		set_err;
+		goto out;
+	}
+
+	err = skel_map_update_elem(map_fd, &key, opts->data, 0);
+	if (err < 0) {
+		opts->errstr = "failed to update loader map";
+		set_err;
+		goto out;
+	}
+
+	memset(&attr, 0, prog_load_attr_sz);
+	attr.prog_type = BPF_PROG_TYPE_SYSCALL;
+	attr.insns = (long) opts->insns;
+	attr.insn_cnt = opts->insns_sz / sizeof(struct bpf_insn);
+	attr.license = (long) "Dual BSD/GPL";
+	memcpy(attr.prog_name, "__loader.prog", sizeof("__loader.prog"));
+	attr.fd_array = (long) &map_fd;
+	attr.log_level = opts->ctx->log_level;
+	attr.log_size = opts->ctx->log_size;
+	attr.log_buf = opts->ctx->log_buf;
+	attr.prog_flags = BPF_F_SLEEPABLE;
+	err = prog_fd = skel_sys_bpf(BPF_PROG_LOAD, &attr, prog_load_attr_sz);
+	if (prog_fd < 0) {
+		opts->errstr = "failed to load loader prog";
+		set_err;
+		goto out;
+	}
+
+	memset(&attr, 0, test_run_attr_sz);
+	attr.test.prog_fd = prog_fd;
+	attr.test.ctx_in = (long) opts->ctx;
+	attr.test.ctx_size_in = opts->ctx->sz;
+	err = skel_sys_bpf(BPF_PROG_RUN, &attr, test_run_attr_sz);
+	if (err < 0 || (int)attr.test.retval < 0) {
+		opts->errstr = "failed to execute loader prog";
+		if (err < 0) {
+			set_err;
+		} else {
+			err = (int)attr.test.retval;
+#ifndef __KERNEL__
+			errno = -err;
+#endif
+		}
+		goto out;
+	}
+	err = 0;
+out:
+	if (map_fd >= 0)
+		close(map_fd);
+	if (prog_fd >= 0)
+		close(prog_fd);
+	return err;
+}
+
+#endif
diff --git a/src/str_error.c b/src/str_error.c
new file mode 100644
index 0000000..146da01
--- /dev/null
+++ b/src/str_error.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+#undef _GNU_SOURCE
+#include <string.h>
+#include <stdio.h>
+#include "str_error.h"
+
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
+/*
+ * Wrapper to allow for building in non-GNU systems such as Alpine Linux's musl
+ * libc, while checking strerror_r() return to avoid having to check this in
+ * all places calling it.
+ */
+char *libbpf_strerror_r(int err, char *dst, int len)
+{
+	int ret = strerror_r(err < 0 ? -err : err, dst, len);
+	if (ret)
+		snprintf(dst, len, "ERROR: strerror_r(%d)=%d", err, ret);
+	return dst;
+}
diff --git a/src/str_error.h b/src/str_error.h
new file mode 100644
index 0000000..a139334
--- /dev/null
+++ b/src/str_error.h
@@ -0,0 +1,6 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __LIBBPF_STR_ERROR_H
+#define __LIBBPF_STR_ERROR_H
+
+char *libbpf_strerror_r(int err, char *dst, int len);
+#endif /* __LIBBPF_STR_ERROR_H */
diff --git a/src/strset.c b/src/strset.c
new file mode 100644
index 0000000..2464bcb
--- /dev/null
+++ b/src/strset.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2021 Facebook */
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <linux/err.h>
+#include "hashmap.h"
+#include "libbpf_internal.h"
+#include "strset.h"
+
+struct strset {
+	void *strs_data;
+	size_t strs_data_len;
+	size_t strs_data_cap;
+	size_t strs_data_max_len;
+
+	/* lookup index for each unique string in strings set */
+	struct hashmap *strs_hash;
+};
+
+static size_t strset_hash_fn(long key, void *ctx)
+{
+	const struct strset *s = ctx;
+	const char *str = s->strs_data + key;
+
+	return str_hash(str);
+}
+
+static bool strset_equal_fn(long key1, long key2, void *ctx)
+{
+	const struct strset *s = ctx;
+	const char *str1 = s->strs_data + key1;
+	const char *str2 = s->strs_data + key2;
+
+	return strcmp(str1, str2) == 0;
+}
+
+struct strset *strset__new(size_t max_data_sz, const char *init_data, size_t init_data_sz)
+{
+	struct strset *set = calloc(1, sizeof(*set));
+	struct hashmap *hash;
+	int err = -ENOMEM;
+
+	if (!set)
+		return ERR_PTR(-ENOMEM);
+
+	hash = hashmap__new(strset_hash_fn, strset_equal_fn, set);
+	if (IS_ERR(hash))
+		goto err_out;
+
+	set->strs_data_max_len = max_data_sz;
+	set->strs_hash = hash;
+
+	if (init_data) {
+		long off;
+
+		set->strs_data = malloc(init_data_sz);
+		if (!set->strs_data)
+			goto err_out;
+
+		memcpy(set->strs_data, init_data, init_data_sz);
+		set->strs_data_len = init_data_sz;
+		set->strs_data_cap = init_data_sz;
+
+		for (off = 0; off < set->strs_data_len; off += strlen(set->strs_data + off) + 1) {
+			/* hashmap__add() returns EEXIST if string with the same
+			 * content already is in the hash map
+			 */
+			err = hashmap__add(hash, off, off);
+			if (err == -EEXIST)
+				continue; /* duplicate */
+			if (err)
+				goto err_out;
+		}
+	}
+
+	return set;
+err_out:
+	strset__free(set);
+	return ERR_PTR(err);
+}
+
+void strset__free(struct strset *set)
+{
+	if (IS_ERR_OR_NULL(set))
+		return;
+
+	hashmap__free(set->strs_hash);
+	free(set->strs_data);
+	free(set);
+}
+
+size_t strset__data_size(const struct strset *set)
+{
+	return set->strs_data_len;
+}
+
+const char *strset__data(const struct strset *set)
+{
+	return set->strs_data;
+}
+
+static void *strset_add_str_mem(struct strset *set, size_t add_sz)
+{
+	return libbpf_add_mem(&set->strs_data, &set->strs_data_cap, 1,
+			      set->strs_data_len, set->strs_data_max_len, add_sz);
+}
+
+/* Find string offset that corresponds to a given string *s*.
+ * Returns:
+ *   - >0 offset into string data, if string is found;
+ *   - -ENOENT, if string is not in the string data;
+ *   - <0, on any other error.
+ */
+int strset__find_str(struct strset *set, const char *s)
+{
+	long old_off, new_off, len;
+	void *p;
+
+	/* see strset__add_str() for why we do this */
+	len = strlen(s) + 1;
+	p = strset_add_str_mem(set, len);
+	if (!p)
+		return -ENOMEM;
+
+	new_off = set->strs_data_len;
+	memcpy(p, s, len);
+
+	if (hashmap__find(set->strs_hash, new_off, &old_off))
+		return old_off;
+
+	return -ENOENT;
+}
+
+/* Add a string s to the string data. If the string already exists, return its
+ * offset within string data.
+ * Returns:
+ *   - > 0 offset into string data, on success;
+ *   - < 0, on error.
+ */
+int strset__add_str(struct strset *set, const char *s)
+{
+	long old_off, new_off, len;
+	void *p;
+	int err;
+
+	/* Hashmap keys are always offsets within set->strs_data, so to even
+	 * look up some string from the "outside", we need to first append it
+	 * at the end, so that it can be addressed with an offset. Luckily,
+	 * until set->strs_data_len is incremented, that string is just a piece
+	 * of garbage for the rest of the code, so no harm, no foul. On the
+	 * other hand, if the string is unique, it's already appended and
+	 * ready to be used, only a simple set->strs_data_len increment away.
+	 */
+	len = strlen(s) + 1;
+	p = strset_add_str_mem(set, len);
+	if (!p)
+		return -ENOMEM;
+
+	new_off = set->strs_data_len;
+	memcpy(p, s, len);
+
+	/* Now attempt to add the string, but only if the string with the same
+	 * contents doesn't exist already (HASHMAP_ADD strategy). If such
+	 * string exists, we'll get its offset in old_off (that's old_key).
+	 */
+	err = hashmap__insert(set->strs_hash, new_off, new_off,
+			      HASHMAP_ADD, &old_off, NULL);
+	if (err == -EEXIST)
+		return old_off; /* duplicated string, return existing offset */
+	if (err)
+		return err;
+
+	set->strs_data_len += len; /* new unique string, adjust data length */
+	return new_off;
+}
diff --git a/src/strset.h b/src/strset.h
new file mode 100644
index 0000000..b6ddf77
--- /dev/null
+++ b/src/strset.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/* Copyright (c) 2021 Facebook */
+#ifndef __LIBBPF_STRSET_H
+#define __LIBBPF_STRSET_H
+
+#include <stdbool.h>
+#include <stddef.h>
+
+struct strset;
+
+struct strset *strset__new(size_t max_data_sz, const char *init_data, size_t init_data_sz);
+void strset__free(struct strset *set);
+
+const char *strset__data(const struct strset *set);
+size_t strset__data_size(const struct strset *set);
+
+int strset__find_str(struct strset *set, const char *s);
+int strset__add_str(struct strset *set, const char *s);
+
+#endif /* __LIBBPF_STRSET_H */
diff --git a/src/usdt.bpf.h b/src/usdt.bpf.h
new file mode 100644
index 0000000..fdfd235
--- /dev/null
+++ b/src/usdt.bpf.h
@@ -0,0 +1,247 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+#ifndef __USDT_BPF_H__
+#define __USDT_BPF_H__
+
+#include <linux/errno.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+/* Below types and maps are internal implementation details of libbpf's USDT
+ * support and are subjects to change. Also, bpf_usdt_xxx() API helpers should
+ * be considered an unstable API as well and might be adjusted based on user
+ * feedback from using libbpf's USDT support in production.
+ */
+
+/* User can override BPF_USDT_MAX_SPEC_CNT to change default size of internal
+ * map that keeps track of USDT argument specifications. This might be
+ * necessary if there are a lot of USDT attachments.
+ */
+#ifndef BPF_USDT_MAX_SPEC_CNT
+#define BPF_USDT_MAX_SPEC_CNT 256
+#endif
+/* User can override BPF_USDT_MAX_IP_CNT to change default size of internal
+ * map that keeps track of IP (memory address) mapping to USDT argument
+ * specification.
+ * Note, if kernel supports BPF cookies, this map is not used and could be
+ * resized all the way to 1 to save a bit of memory.
+ */
+#ifndef BPF_USDT_MAX_IP_CNT
+#define BPF_USDT_MAX_IP_CNT (4 * BPF_USDT_MAX_SPEC_CNT)
+#endif
+
+enum __bpf_usdt_arg_type {
+	BPF_USDT_ARG_CONST,
+	BPF_USDT_ARG_REG,
+	BPF_USDT_ARG_REG_DEREF,
+};
+
+struct __bpf_usdt_arg_spec {
+	/* u64 scalar interpreted depending on arg_type, see below */
+	__u64 val_off;
+	/* arg location case, see bpf_udst_arg() for details */
+	enum __bpf_usdt_arg_type arg_type;
+	/* offset of referenced register within struct pt_regs */
+	short reg_off;
+	/* whether arg should be interpreted as signed value */
+	bool arg_signed;
+	/* number of bits that need to be cleared and, optionally,
+	 * sign-extended to cast arguments that are 1, 2, or 4 bytes
+	 * long into final 8-byte u64/s64 value returned to user
+	 */
+	char arg_bitshift;
+};
+
+/* should match USDT_MAX_ARG_CNT in usdt.c exactly */
+#define BPF_USDT_MAX_ARG_CNT 12
+struct __bpf_usdt_spec {
+	struct __bpf_usdt_arg_spec args[BPF_USDT_MAX_ARG_CNT];
+	__u64 usdt_cookie;
+	short arg_cnt;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, BPF_USDT_MAX_SPEC_CNT);
+	__type(key, int);
+	__type(value, struct __bpf_usdt_spec);
+} __bpf_usdt_specs SEC(".maps") __weak;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, BPF_USDT_MAX_IP_CNT);
+	__type(key, long);
+	__type(value, __u32);
+} __bpf_usdt_ip_to_spec_id SEC(".maps") __weak;
+
+extern const _Bool LINUX_HAS_BPF_COOKIE __kconfig;
+
+static __always_inline
+int __bpf_usdt_spec_id(struct pt_regs *ctx)
+{
+	if (!LINUX_HAS_BPF_COOKIE) {
+		long ip = PT_REGS_IP(ctx);
+		int *spec_id_ptr;
+
+		spec_id_ptr = bpf_map_lookup_elem(&__bpf_usdt_ip_to_spec_id, &ip);
+		return spec_id_ptr ? *spec_id_ptr : -ESRCH;
+	}
+
+	return bpf_get_attach_cookie(ctx);
+}
+
+/* Return number of USDT arguments defined for currently traced USDT. */
+__weak __hidden
+int bpf_usdt_arg_cnt(struct pt_regs *ctx)
+{
+	struct __bpf_usdt_spec *spec;
+	int spec_id;
+
+	spec_id = __bpf_usdt_spec_id(ctx);
+	if (spec_id < 0)
+		return -ESRCH;
+
+	spec = bpf_map_lookup_elem(&__bpf_usdt_specs, &spec_id);
+	if (!spec)
+		return -ESRCH;
+
+	return spec->arg_cnt;
+}
+
+/* Fetch USDT argument #*arg_num* (zero-indexed) and put its value into *res.
+ * Returns 0 on success; negative error, otherwise.
+ * On error *res is guaranteed to be set to zero.
+ */
+__weak __hidden
+int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res)
+{
+	struct __bpf_usdt_spec *spec;
+	struct __bpf_usdt_arg_spec *arg_spec;
+	unsigned long val;
+	int err, spec_id;
+
+	*res = 0;
+
+	spec_id = __bpf_usdt_spec_id(ctx);
+	if (spec_id < 0)
+		return -ESRCH;
+
+	spec = bpf_map_lookup_elem(&__bpf_usdt_specs, &spec_id);
+	if (!spec)
+		return -ESRCH;
+
+	if (arg_num >= BPF_USDT_MAX_ARG_CNT || arg_num >= spec->arg_cnt)
+		return -ENOENT;
+
+	arg_spec = &spec->args[arg_num];
+	switch (arg_spec->arg_type) {
+	case BPF_USDT_ARG_CONST:
+		/* Arg is just a constant ("-4@$-9" in USDT arg spec).
+		 * value is recorded in arg_spec->val_off directly.
+		 */
+		val = arg_spec->val_off;
+		break;
+	case BPF_USDT_ARG_REG:
+		/* Arg is in a register (e.g, "8@%rax" in USDT arg spec),
+		 * so we read the contents of that register directly from
+		 * struct pt_regs. To keep things simple user-space parts
+		 * record offsetof(struct pt_regs, <regname>) in arg_spec->reg_off.
+		 */
+		err = bpf_probe_read_kernel(&val, sizeof(val), (void *)ctx + arg_spec->reg_off);
+		if (err)
+			return err;
+		break;
+	case BPF_USDT_ARG_REG_DEREF:
+		/* Arg is in memory addressed by register, plus some offset
+		 * (e.g., "-4@-1204(%rbp)" in USDT arg spec). Register is
+		 * identified like with BPF_USDT_ARG_REG case, and the offset
+		 * is in arg_spec->val_off. We first fetch register contents
+		 * from pt_regs, then do another user-space probe read to
+		 * fetch argument value itself.
+		 */
+		err = bpf_probe_read_kernel(&val, sizeof(val), (void *)ctx + arg_spec->reg_off);
+		if (err)
+			return err;
+		err = bpf_probe_read_user(&val, sizeof(val), (void *)val + arg_spec->val_off);
+		if (err)
+			return err;
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+		val >>= arg_spec->arg_bitshift;
+#endif
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* cast arg from 1, 2, or 4 bytes to final 8 byte size clearing
+	 * necessary upper arg_bitshift bits, with sign extension if argument
+	 * is signed
+	 */
+	val <<= arg_spec->arg_bitshift;
+	if (arg_spec->arg_signed)
+		val = ((long)val) >> arg_spec->arg_bitshift;
+	else
+		val = val >> arg_spec->arg_bitshift;
+	*res = val;
+	return 0;
+}
+
+/* Retrieve user-specified cookie value provided during attach as
+ * bpf_usdt_opts.usdt_cookie. This serves the same purpose as BPF cookie
+ * returned by bpf_get_attach_cookie(). Libbpf's support for USDT is itself
+ * utilizing BPF cookies internally, so user can't use BPF cookie directly
+ * for USDT programs and has to use bpf_usdt_cookie() API instead.
+ */
+__weak __hidden
+long bpf_usdt_cookie(struct pt_regs *ctx)
+{
+	struct __bpf_usdt_spec *spec;
+	int spec_id;
+
+	spec_id = __bpf_usdt_spec_id(ctx);
+	if (spec_id < 0)
+		return 0;
+
+	spec = bpf_map_lookup_elem(&__bpf_usdt_specs, &spec_id);
+	if (!spec)
+		return 0;
+
+	return spec->usdt_cookie;
+}
+
+/* we rely on ___bpf_apply() and ___bpf_narg() macros already defined in bpf_tracing.h */
+#define ___bpf_usdt_args0() ctx
+#define ___bpf_usdt_args1(x) ___bpf_usdt_args0(), ({ long _x; bpf_usdt_arg(ctx, 0, &_x); (void *)_x; })
+#define ___bpf_usdt_args2(x, args...) ___bpf_usdt_args1(args), ({ long _x; bpf_usdt_arg(ctx, 1, &_x); (void *)_x; })
+#define ___bpf_usdt_args3(x, args...) ___bpf_usdt_args2(args), ({ long _x; bpf_usdt_arg(ctx, 2, &_x); (void *)_x; })
+#define ___bpf_usdt_args4(x, args...) ___bpf_usdt_args3(args), ({ long _x; bpf_usdt_arg(ctx, 3, &_x); (void *)_x; })
+#define ___bpf_usdt_args5(x, args...) ___bpf_usdt_args4(args), ({ long _x; bpf_usdt_arg(ctx, 4, &_x); (void *)_x; })
+#define ___bpf_usdt_args6(x, args...) ___bpf_usdt_args5(args), ({ long _x; bpf_usdt_arg(ctx, 5, &_x); (void *)_x; })
+#define ___bpf_usdt_args7(x, args...) ___bpf_usdt_args6(args), ({ long _x; bpf_usdt_arg(ctx, 6, &_x); (void *)_x; })
+#define ___bpf_usdt_args8(x, args...) ___bpf_usdt_args7(args), ({ long _x; bpf_usdt_arg(ctx, 7, &_x); (void *)_x; })
+#define ___bpf_usdt_args9(x, args...) ___bpf_usdt_args8(args), ({ long _x; bpf_usdt_arg(ctx, 8, &_x); (void *)_x; })
+#define ___bpf_usdt_args10(x, args...) ___bpf_usdt_args9(args), ({ long _x; bpf_usdt_arg(ctx, 9, &_x); (void *)_x; })
+#define ___bpf_usdt_args11(x, args...) ___bpf_usdt_args10(args), ({ long _x; bpf_usdt_arg(ctx, 10, &_x); (void *)_x; })
+#define ___bpf_usdt_args12(x, args...) ___bpf_usdt_args11(args), ({ long _x; bpf_usdt_arg(ctx, 11, &_x); (void *)_x; })
+#define ___bpf_usdt_args(args...) ___bpf_apply(___bpf_usdt_args, ___bpf_narg(args))(args)
+
+/*
+ * BPF_USDT serves the same purpose for USDT handlers as BPF_PROG for
+ * tp_btf/fentry/fexit BPF programs and BPF_KPROBE for kprobes.
+ * Original struct pt_regs * context is preserved as 'ctx' argument.
+ */
+#define BPF_USDT(name, args...)						    \
+name(struct pt_regs *ctx);						    \
+static __always_inline typeof(name(0))					    \
+____##name(struct pt_regs *ctx, ##args);				    \
+typeof(name(0)) name(struct pt_regs *ctx)				    \
+{									    \
+        _Pragma("GCC diagnostic push")					    \
+        _Pragma("GCC diagnostic ignored \"-Wint-conversion\"")		    \
+        return ____##name(___bpf_usdt_args(args));			    \
+        _Pragma("GCC diagnostic pop")					    \
+}									    \
+static __always_inline typeof(name(0))					    \
+____##name(struct pt_regs *ctx, ##args)
+
+#endif /* __USDT_BPF_H__ */
diff --git a/src/usdt.c b/src/usdt.c
new file mode 100644
index 0000000..75b411f
--- /dev/null
+++ b/src/usdt.c
@@ -0,0 +1,1516 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libelf.h>
+#include <gelf.h>
+#include <unistd.h>
+#include <linux/ptrace.h>
+#include <linux/kernel.h>
+
+/* s8 will be marked as poison while it's a reg of riscv */
+#if defined(__riscv)
+#define rv_s8 s8
+#endif
+
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_common.h"
+#include "libbpf_internal.h"
+#include "hashmap.h"
+
+/* libbpf's USDT support consists of BPF-side state/code and user-space
+ * state/code working together in concert. BPF-side parts are defined in
+ * usdt.bpf.h header library. User-space state is encapsulated by struct
+ * usdt_manager and all the supporting code centered around usdt_manager.
+ *
+ * usdt.bpf.h defines two BPF maps that usdt_manager expects: USDT spec map
+ * and IP-to-spec-ID map, which is auxiliary map necessary for kernels that
+ * don't support BPF cookie (see below). These two maps are implicitly
+ * embedded into user's end BPF object file when user's code included
+ * usdt.bpf.h. This means that libbpf doesn't do anything special to create
+ * these USDT support maps. They are created by normal libbpf logic of
+ * instantiating BPF maps when opening and loading BPF object.
+ *
+ * As such, libbpf is basically unaware of the need to do anything
+ * USDT-related until the very first call to bpf_program__attach_usdt(), which
+ * can be called by user explicitly or happen automatically during skeleton
+ * attach (or, equivalently, through generic bpf_program__attach() call). At
+ * this point, libbpf will instantiate and initialize struct usdt_manager and
+ * store it in bpf_object. USDT manager is per-BPF object construct, as each
+ * independent BPF object might or might not have USDT programs, and thus all
+ * the expected USDT-related state. There is no coordination between two
+ * bpf_object in parts of USDT attachment, they are oblivious of each other's
+ * existence and libbpf is just oblivious, dealing with bpf_object-specific
+ * USDT state.
+ *
+ * Quick crash course on USDTs.
+ *
+ * From user-space application's point of view, USDT is essentially just
+ * a slightly special function call that normally has zero overhead, unless it
+ * is being traced by some external entity (e.g, BPF-based tool). Here's how
+ * a typical application can trigger USDT probe:
+ *
+ * #include <sys/sdt.h>  // provided by systemtap-sdt-devel package
+ * // folly also provide similar functionality in folly/tracing/StaticTracepoint.h
+ *
+ * STAP_PROBE3(my_usdt_provider, my_usdt_probe_name, 123, x, &y);
+ *
+ * USDT is identified by it's <provider-name>:<probe-name> pair of names. Each
+ * individual USDT has a fixed number of arguments (3 in the above example)
+ * and specifies values of each argument as if it was a function call.
+ *
+ * USDT call is actually not a function call, but is instead replaced by
+ * a single NOP instruction (thus zero overhead, effectively). But in addition
+ * to that, those USDT macros generate special SHT_NOTE ELF records in
+ * .note.stapsdt ELF section. Here's an example USDT definition as emitted by
+ * `readelf -n <binary>`:
+ *
+ *   stapsdt              0x00000089       NT_STAPSDT (SystemTap probe descriptors)
+ *   Provider: test
+ *   Name: usdt12
+ *   Location: 0x0000000000549df3, Base: 0x00000000008effa4, Semaphore: 0x0000000000a4606e
+ *   Arguments: -4@-1204(%rbp) -4@%edi -8@-1216(%rbp) -8@%r8 -4@$5 -8@%r9 8@%rdx 8@%r10 -4@$-9 -2@%cx -2@%ax -1@%sil
+ *
+ * In this case we have USDT test:usdt12 with 12 arguments.
+ *
+ * Location and base are offsets used to calculate absolute IP address of that
+ * NOP instruction that kernel can replace with an interrupt instruction to
+ * trigger instrumentation code (BPF program for all that we care about).
+ *
+ * Semaphore above is and optional feature. It records an address of a 2-byte
+ * refcount variable (normally in '.probes' ELF section) used for signaling if
+ * there is anything that is attached to USDT. This is useful for user
+ * applications if, for example, they need to prepare some arguments that are
+ * passed only to USDTs and preparation is expensive. By checking if USDT is
+ * "activated", an application can avoid paying those costs unnecessarily.
+ * Recent enough kernel has built-in support for automatically managing this
+ * refcount, which libbpf expects and relies on. If USDT is defined without
+ * associated semaphore, this value will be zero. See selftests for semaphore
+ * examples.
+ *
+ * Arguments is the most interesting part. This USDT specification string is
+ * providing information about all the USDT arguments and their locations. The
+ * part before @ sign defined byte size of the argument (1, 2, 4, or 8) and
+ * whether the argument is signed or unsigned (negative size means signed).
+ * The part after @ sign is assembly-like definition of argument location
+ * (see [0] for more details). Technically, assembler can provide some pretty
+ * advanced definitions, but libbpf is currently supporting three most common
+ * cases:
+ *   1) immediate constant, see 5th and 9th args above (-4@$5 and -4@-9);
+ *   2) register value, e.g., 8@%rdx, which means "unsigned 8-byte integer
+ *      whose value is in register %rdx";
+ *   3) memory dereference addressed by register, e.g., -4@-1204(%rbp), which
+ *      specifies signed 32-bit integer stored at offset -1204 bytes from
+ *      memory address stored in %rbp.
+ *
+ *   [0] https://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation
+ *
+ * During attachment, libbpf parses all the relevant USDT specifications and
+ * prepares `struct usdt_spec` (USDT spec), which is then provided to BPF-side
+ * code through spec map. This allows BPF applications to quickly fetch the
+ * actual value at runtime using a simple BPF-side code.
+ *
+ * With basics out of the way, let's go over less immediately obvious aspects
+ * of supporting USDTs.
+ *
+ * First, there is no special USDT BPF program type. It is actually just
+ * a uprobe BPF program (which for kernel, at least currently, is just a kprobe
+ * program, so BPF_PROG_TYPE_KPROBE program type). With the only difference
+ * that uprobe is usually attached at the function entry, while USDT will
+ * normally will be somewhere inside the function. But it should always be
+ * pointing to NOP instruction, which makes such uprobes the fastest uprobe
+ * kind.
+ *
+ * Second, it's important to realize that such STAP_PROBEn(provider, name, ...)
+ * macro invocations can end up being inlined many-many times, depending on
+ * specifics of each individual user application. So single conceptual USDT
+ * (identified by provider:name pair of identifiers) is, generally speaking,
+ * multiple uprobe locations (USDT call sites) in different places in user
+ * application. Further, again due to inlining, each USDT call site might end
+ * up having the same argument #N be located in a different place. In one call
+ * site it could be a constant, in another will end up in a register, and in
+ * yet another could be some other register or even somewhere on the stack.
+ *
+ * As such, "attaching to USDT" means (in general case) attaching the same
+ * uprobe BPF program to multiple target locations in user application, each
+ * potentially having a completely different USDT spec associated with it.
+ * To wire all this up together libbpf allocates a unique integer spec ID for
+ * each unique USDT spec. Spec IDs are allocated as sequential small integers
+ * so that they can be used as keys in array BPF map (for performance reasons).
+ * Spec ID allocation and accounting is big part of what usdt_manager is
+ * about. This state has to be maintained per-BPF object and coordinate
+ * between different USDT attachments within the same BPF object.
+ *
+ * Spec ID is the key in spec BPF map, value is the actual USDT spec layed out
+ * as struct usdt_spec. Each invocation of BPF program at runtime needs to
+ * know its associated spec ID. It gets it either through BPF cookie, which
+ * libbpf sets to spec ID during attach time, or, if kernel is too old to
+ * support BPF cookie, through IP-to-spec-ID map that libbpf maintains in such
+ * case. The latter means that some modes of operation can't be supported
+ * without BPF cookie. Such mode is attaching to shared library "generically",
+ * without specifying target process. In such case, it's impossible to
+ * calculate absolute IP addresses for IP-to-spec-ID map, and thus such mode
+ * is not supported without BPF cookie support.
+ *
+ * Note that libbpf is using BPF cookie functionality for its own internal
+ * needs, so user itself can't rely on BPF cookie feature. To that end, libbpf
+ * provides conceptually equivalent USDT cookie support. It's still u64
+ * user-provided value that can be associated with USDT attachment. Note that
+ * this will be the same value for all USDT call sites within the same single
+ * *logical* USDT attachment. This makes sense because to user attaching to
+ * USDT is a single BPF program triggered for singular USDT probe. The fact
+ * that this is done at multiple actual locations is a mostly hidden
+ * implementation details. This USDT cookie value can be fetched with
+ * bpf_usdt_cookie(ctx) API provided by usdt.bpf.h
+ *
+ * Lastly, while single USDT can have tons of USDT call sites, it doesn't
+ * necessarily have that many different USDT specs. It very well might be
+ * that 1000 USDT call sites only need 5 different USDT specs, because all the
+ * arguments are typically contained in a small set of registers or stack
+ * locations. As such, it's wasteful to allocate as many USDT spec IDs as
+ * there are USDT call sites. So libbpf tries to be frugal and performs
+ * on-the-fly deduplication during a single USDT attachment to only allocate
+ * the minimal required amount of unique USDT specs (and thus spec IDs). This
+ * is trivially achieved by using USDT spec string (Arguments string from USDT
+ * note) as a lookup key in a hashmap. USDT spec string uniquely defines
+ * everything about how to fetch USDT arguments, so two USDT call sites
+ * sharing USDT spec string can safely share the same USDT spec and spec ID.
+ * Note, this spec string deduplication is happening only during the same USDT
+ * attachment, so each USDT spec shares the same USDT cookie value. This is
+ * not generally true for other USDT attachments within the same BPF object,
+ * as even if USDT spec string is the same, USDT cookie value can be
+ * different. It was deemed excessive to try to deduplicate across independent
+ * USDT attachments by taking into account USDT spec string *and* USDT cookie
+ * value, which would complicated spec ID accounting significantly for little
+ * gain.
+ */
+
+#define USDT_BASE_SEC ".stapsdt.base"
+#define USDT_SEMA_SEC ".probes"
+#define USDT_NOTE_SEC  ".note.stapsdt"
+#define USDT_NOTE_TYPE 3
+#define USDT_NOTE_NAME "stapsdt"
+
+/* should match exactly enum __bpf_usdt_arg_type from usdt.bpf.h */
+enum usdt_arg_type {
+	USDT_ARG_CONST,
+	USDT_ARG_REG,
+	USDT_ARG_REG_DEREF,
+};
+
+/* should match exactly struct __bpf_usdt_arg_spec from usdt.bpf.h */
+struct usdt_arg_spec {
+	__u64 val_off;
+	enum usdt_arg_type arg_type;
+	short reg_off;
+	bool arg_signed;
+	char arg_bitshift;
+};
+
+/* should match BPF_USDT_MAX_ARG_CNT in usdt.bpf.h */
+#define USDT_MAX_ARG_CNT 12
+
+/* should match struct __bpf_usdt_spec from usdt.bpf.h */
+struct usdt_spec {
+	struct usdt_arg_spec args[USDT_MAX_ARG_CNT];
+	__u64 usdt_cookie;
+	short arg_cnt;
+};
+
+struct usdt_note {
+	const char *provider;
+	const char *name;
+	/* USDT args specification string, e.g.:
+	 * "-4@%esi -4@-24(%rbp) -4@%ecx 2@%ax 8@%rdx"
+	 */
+	const char *args;
+	long loc_addr;
+	long base_addr;
+	long sema_addr;
+};
+
+struct usdt_target {
+	long abs_ip;
+	long rel_ip;
+	long sema_off;
+	struct usdt_spec spec;
+	const char *spec_str;
+};
+
+struct usdt_manager {
+	struct bpf_map *specs_map;
+	struct bpf_map *ip_to_spec_id_map;
+
+	int *free_spec_ids;
+	size_t free_spec_cnt;
+	size_t next_free_spec_id;
+
+	bool has_bpf_cookie;
+	bool has_sema_refcnt;
+};
+
+struct usdt_manager *usdt_manager_new(struct bpf_object *obj)
+{
+	static const char *ref_ctr_sysfs_path = "/sys/bus/event_source/devices/uprobe/format/ref_ctr_offset";
+	struct usdt_manager *man;
+	struct bpf_map *specs_map, *ip_to_spec_id_map;
+
+	specs_map = bpf_object__find_map_by_name(obj, "__bpf_usdt_specs");
+	ip_to_spec_id_map = bpf_object__find_map_by_name(obj, "__bpf_usdt_ip_to_spec_id");
+	if (!specs_map || !ip_to_spec_id_map) {
+		pr_warn("usdt: failed to find USDT support BPF maps, did you forget to include bpf/usdt.bpf.h?\n");
+		return ERR_PTR(-ESRCH);
+	}
+
+	man = calloc(1, sizeof(*man));
+	if (!man)
+		return ERR_PTR(-ENOMEM);
+
+	man->specs_map = specs_map;
+	man->ip_to_spec_id_map = ip_to_spec_id_map;
+
+	/* Detect if BPF cookie is supported for kprobes.
+	 * We don't need IP-to-ID mapping if we can use BPF cookies.
+	 * Added in: 7adfc6c9b315 ("bpf: Add bpf_get_attach_cookie() BPF helper to access bpf_cookie value")
+	 */
+	man->has_bpf_cookie = kernel_supports(obj, FEAT_BPF_COOKIE);
+
+	/* Detect kernel support for automatic refcounting of USDT semaphore.
+	 * If this is not supported, USDTs with semaphores will not be supported.
+	 * Added in: a6ca88b241d5 ("trace_uprobe: support reference counter in fd-based uprobe")
+	 */
+	man->has_sema_refcnt = faccessat(AT_FDCWD, ref_ctr_sysfs_path, F_OK, AT_EACCESS) == 0;
+
+	return man;
+}
+
+void usdt_manager_free(struct usdt_manager *man)
+{
+	if (IS_ERR_OR_NULL(man))
+		return;
+
+	free(man->free_spec_ids);
+	free(man);
+}
+
+static int sanity_check_usdt_elf(Elf *elf, const char *path)
+{
+	GElf_Ehdr ehdr;
+	int endianness;
+
+	if (elf_kind(elf) != ELF_K_ELF) {
+		pr_warn("usdt: unrecognized ELF kind %d for '%s'\n", elf_kind(elf), path);
+		return -EBADF;
+	}
+
+	switch (gelf_getclass(elf)) {
+	case ELFCLASS64:
+		if (sizeof(void *) != 8) {
+			pr_warn("usdt: attaching to 64-bit ELF binary '%s' is not supported\n", path);
+			return -EBADF;
+		}
+		break;
+	case ELFCLASS32:
+		if (sizeof(void *) != 4) {
+			pr_warn("usdt: attaching to 32-bit ELF binary '%s' is not supported\n", path);
+			return -EBADF;
+		}
+		break;
+	default:
+		pr_warn("usdt: unsupported ELF class for '%s'\n", path);
+		return -EBADF;
+	}
+
+	if (!gelf_getehdr(elf, &ehdr))
+		return -EINVAL;
+
+	if (ehdr.e_type != ET_EXEC && ehdr.e_type != ET_DYN) {
+		pr_warn("usdt: unsupported type of ELF binary '%s' (%d), only ET_EXEC and ET_DYN are supported\n",
+			path, ehdr.e_type);
+		return -EBADF;
+	}
+
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	endianness = ELFDATA2LSB;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+	endianness = ELFDATA2MSB;
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+	if (endianness != ehdr.e_ident[EI_DATA]) {
+		pr_warn("usdt: ELF endianness mismatch for '%s'\n", path);
+		return -EBADF;
+	}
+
+	return 0;
+}
+
+static int find_elf_sec_by_name(Elf *elf, const char *sec_name, GElf_Shdr *shdr, Elf_Scn **scn)
+{
+	Elf_Scn *sec = NULL;
+	size_t shstrndx;
+
+	if (elf_getshdrstrndx(elf, &shstrndx))
+		return -EINVAL;
+
+	/* check if ELF is corrupted and avoid calling elf_strptr if yes */
+	if (!elf_rawdata(elf_getscn(elf, shstrndx), NULL))
+		return -EINVAL;
+
+	while ((sec = elf_nextscn(elf, sec)) != NULL) {
+		char *name;
+
+		if (!gelf_getshdr(sec, shdr))
+			return -EINVAL;
+
+		name = elf_strptr(elf, shstrndx, shdr->sh_name);
+		if (name && strcmp(sec_name, name) == 0) {
+			*scn = sec;
+			return 0;
+		}
+	}
+
+	return -ENOENT;
+}
+
+struct elf_seg {
+	long start;
+	long end;
+	long offset;
+	bool is_exec;
+};
+
+static int cmp_elf_segs(const void *_a, const void *_b)
+{
+	const struct elf_seg *a = _a;
+	const struct elf_seg *b = _b;
+
+	return a->start < b->start ? -1 : 1;
+}
+
+static int parse_elf_segs(Elf *elf, const char *path, struct elf_seg **segs, size_t *seg_cnt)
+{
+	GElf_Phdr phdr;
+	size_t n;
+	int i, err;
+	struct elf_seg *seg;
+	void *tmp;
+
+	*seg_cnt = 0;
+
+	if (elf_getphdrnum(elf, &n)) {
+		err = -errno;
+		return err;
+	}
+
+	for (i = 0; i < n; i++) {
+		if (!gelf_getphdr(elf, i, &phdr)) {
+			err = -errno;
+			return err;
+		}
+
+		pr_debug("usdt: discovered PHDR #%d in '%s': vaddr 0x%lx memsz 0x%lx offset 0x%lx type 0x%lx flags 0x%lx\n",
+			 i, path, (long)phdr.p_vaddr, (long)phdr.p_memsz, (long)phdr.p_offset,
+			 (long)phdr.p_type, (long)phdr.p_flags);
+		if (phdr.p_type != PT_LOAD)
+			continue;
+
+		tmp = libbpf_reallocarray(*segs, *seg_cnt + 1, sizeof(**segs));
+		if (!tmp)
+			return -ENOMEM;
+
+		*segs = tmp;
+		seg = *segs + *seg_cnt;
+		(*seg_cnt)++;
+
+		seg->start = phdr.p_vaddr;
+		seg->end = phdr.p_vaddr + phdr.p_memsz;
+		seg->offset = phdr.p_offset;
+		seg->is_exec = phdr.p_flags & PF_X;
+	}
+
+	if (*seg_cnt == 0) {
+		pr_warn("usdt: failed to find PT_LOAD program headers in '%s'\n", path);
+		return -ESRCH;
+	}
+
+	qsort(*segs, *seg_cnt, sizeof(**segs), cmp_elf_segs);
+	return 0;
+}
+
+static int parse_vma_segs(int pid, const char *lib_path, struct elf_seg **segs, size_t *seg_cnt)
+{
+	char path[PATH_MAX], line[PATH_MAX], mode[16];
+	size_t seg_start, seg_end, seg_off;
+	struct elf_seg *seg;
+	int tmp_pid, i, err;
+	FILE *f;
+
+	*seg_cnt = 0;
+
+	/* Handle containerized binaries only accessible from
+	 * /proc/<pid>/root/<path>. They will be reported as just /<path> in
+	 * /proc/<pid>/maps.
+	 */
+	if (sscanf(lib_path, "/proc/%d/root%s", &tmp_pid, path) == 2 && pid == tmp_pid)
+		goto proceed;
+
+	if (!realpath(lib_path, path)) {
+		pr_warn("usdt: failed to get absolute path of '%s' (err %d), using path as is...\n",
+			lib_path, -errno);
+		libbpf_strlcpy(path, lib_path, sizeof(path));
+	}
+
+proceed:
+	sprintf(line, "/proc/%d/maps", pid);
+	f = fopen(line, "r");
+	if (!f) {
+		err = -errno;
+		pr_warn("usdt: failed to open '%s' to get base addr of '%s': %d\n",
+			line, lib_path, err);
+		return err;
+	}
+
+	/* We need to handle lines with no path at the end:
+	 *
+	 * 7f5c6f5d1000-7f5c6f5d3000 rw-p 001c7000 08:04 21238613      /usr/lib64/libc-2.17.so
+	 * 7f5c6f5d3000-7f5c6f5d8000 rw-p 00000000 00:00 0
+	 * 7f5c6f5d8000-7f5c6f5d9000 r-xp 00000000 103:01 362990598    /data/users/andriin/linux/tools/bpf/usdt/libhello_usdt.so
+	 */
+	while (fscanf(f, "%zx-%zx %s %zx %*s %*d%[^\n]\n",
+		      &seg_start, &seg_end, mode, &seg_off, line) == 5) {
+		void *tmp;
+
+		/* to handle no path case (see above) we need to capture line
+		 * without skipping any whitespaces. So we need to strip
+		 * leading whitespaces manually here
+		 */
+		i = 0;
+		while (isblank(line[i]))
+			i++;
+		if (strcmp(line + i, path) != 0)
+			continue;
+
+		pr_debug("usdt: discovered segment for lib '%s': addrs %zx-%zx mode %s offset %zx\n",
+			 path, seg_start, seg_end, mode, seg_off);
+
+		/* ignore non-executable sections for shared libs */
+		if (mode[2] != 'x')
+			continue;
+
+		tmp = libbpf_reallocarray(*segs, *seg_cnt + 1, sizeof(**segs));
+		if (!tmp) {
+			err = -ENOMEM;
+			goto err_out;
+		}
+
+		*segs = tmp;
+		seg = *segs + *seg_cnt;
+		*seg_cnt += 1;
+
+		seg->start = seg_start;
+		seg->end = seg_end;
+		seg->offset = seg_off;
+		seg->is_exec = true;
+	}
+
+	if (*seg_cnt == 0) {
+		pr_warn("usdt: failed to find '%s' (resolved to '%s') within PID %d memory mappings\n",
+			lib_path, path, pid);
+		err = -ESRCH;
+		goto err_out;
+	}
+
+	qsort(*segs, *seg_cnt, sizeof(**segs), cmp_elf_segs);
+	err = 0;
+err_out:
+	fclose(f);
+	return err;
+}
+
+static struct elf_seg *find_elf_seg(struct elf_seg *segs, size_t seg_cnt, long virtaddr)
+{
+	struct elf_seg *seg;
+	int i;
+
+	/* for ELF binaries (both executables and shared libraries), we are
+	 * given virtual address (absolute for executables, relative for
+	 * libraries) which should match address range of [seg_start, seg_end)
+	 */
+	for (i = 0, seg = segs; i < seg_cnt; i++, seg++) {
+		if (seg->start <= virtaddr && virtaddr < seg->end)
+			return seg;
+	}
+	return NULL;
+}
+
+static struct elf_seg *find_vma_seg(struct elf_seg *segs, size_t seg_cnt, long offset)
+{
+	struct elf_seg *seg;
+	int i;
+
+	/* for VMA segments from /proc/<pid>/maps file, provided "address" is
+	 * actually a file offset, so should be fall within logical
+	 * offset-based range of [offset_start, offset_end)
+	 */
+	for (i = 0, seg = segs; i < seg_cnt; i++, seg++) {
+		if (seg->offset <= offset && offset < seg->offset + (seg->end - seg->start))
+			return seg;
+	}
+	return NULL;
+}
+
+static int parse_usdt_note(Elf *elf, const char *path, GElf_Nhdr *nhdr,
+			   const char *data, size_t name_off, size_t desc_off,
+			   struct usdt_note *usdt_note);
+
+static int parse_usdt_spec(struct usdt_spec *spec, const struct usdt_note *note, __u64 usdt_cookie);
+
+static int collect_usdt_targets(struct usdt_manager *man, Elf *elf, const char *path, pid_t pid,
+				const char *usdt_provider, const char *usdt_name, __u64 usdt_cookie,
+				struct usdt_target **out_targets, size_t *out_target_cnt)
+{
+	size_t off, name_off, desc_off, seg_cnt = 0, vma_seg_cnt = 0, target_cnt = 0;
+	struct elf_seg *segs = NULL, *vma_segs = NULL;
+	struct usdt_target *targets = NULL, *target;
+	long base_addr = 0;
+	Elf_Scn *notes_scn, *base_scn;
+	GElf_Shdr base_shdr, notes_shdr;
+	GElf_Ehdr ehdr;
+	GElf_Nhdr nhdr;
+	Elf_Data *data;
+	int err;
+
+	*out_targets = NULL;
+	*out_target_cnt = 0;
+
+	err = find_elf_sec_by_name(elf, USDT_NOTE_SEC, &notes_shdr, &notes_scn);
+	if (err) {
+		pr_warn("usdt: no USDT notes section (%s) found in '%s'\n", USDT_NOTE_SEC, path);
+		return err;
+	}
+
+	if (notes_shdr.sh_type != SHT_NOTE || !gelf_getehdr(elf, &ehdr)) {
+		pr_warn("usdt: invalid USDT notes section (%s) in '%s'\n", USDT_NOTE_SEC, path);
+		return -EINVAL;
+	}
+
+	err = parse_elf_segs(elf, path, &segs, &seg_cnt);
+	if (err) {
+		pr_warn("usdt: failed to process ELF program segments for '%s': %d\n", path, err);
+		goto err_out;
+	}
+
+	/* .stapsdt.base ELF section is optional, but is used for prelink
+	 * offset compensation (see a big comment further below)
+	 */
+	if (find_elf_sec_by_name(elf, USDT_BASE_SEC, &base_shdr, &base_scn) == 0)
+		base_addr = base_shdr.sh_addr;
+
+	data = elf_getdata(notes_scn, 0);
+	off = 0;
+	while ((off = gelf_getnote(data, off, &nhdr, &name_off, &desc_off)) > 0) {
+		long usdt_abs_ip, usdt_rel_ip, usdt_sema_off = 0;
+		struct usdt_note note;
+		struct elf_seg *seg = NULL;
+		void *tmp;
+
+		err = parse_usdt_note(elf, path, &nhdr, data->d_buf, name_off, desc_off, &note);
+		if (err)
+			goto err_out;
+
+		if (strcmp(note.provider, usdt_provider) != 0 || strcmp(note.name, usdt_name) != 0)
+			continue;
+
+		/* We need to compensate "prelink effect". See [0] for details,
+		 * relevant parts quoted here:
+		 *
+		 * Each SDT probe also expands into a non-allocated ELF note. You can
+		 * find this by looking at SHT_NOTE sections and decoding the format;
+		 * see below for details. Because the note is non-allocated, it means
+		 * there is no runtime cost, and also preserved in both stripped files
+		 * and .debug files.
+		 *
+		 * However, this means that prelink won't adjust the note's contents
+		 * for address offsets. Instead, this is done via the .stapsdt.base
+		 * section. This is a special section that is added to the text. We
+		 * will only ever have one of these sections in a final link and it
+		 * will only ever be one byte long. Nothing about this section itself
+		 * matters, we just use it as a marker to detect prelink address
+		 * adjustments.
+		 *
+		 * Each probe note records the link-time address of the .stapsdt.base
+		 * section alongside the probe PC address. The decoder compares the
+		 * base address stored in the note with the .stapsdt.base section's
+		 * sh_addr. Initially these are the same, but the section header will
+		 * be adjusted by prelink. So the decoder applies the difference to
+		 * the probe PC address to get the correct prelinked PC address; the
+		 * same adjustment is applied to the semaphore address, if any.
+		 *
+		 *   [0] https://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation
+		 */
+		usdt_abs_ip = note.loc_addr;
+		if (base_addr)
+			usdt_abs_ip += base_addr - note.base_addr;
+
+		/* When attaching uprobes (which is what USDTs basically are)
+		 * kernel expects file offset to be specified, not a relative
+		 * virtual address, so we need to translate virtual address to
+		 * file offset, for both ET_EXEC and ET_DYN binaries.
+		 */
+		seg = find_elf_seg(segs, seg_cnt, usdt_abs_ip);
+		if (!seg) {
+			err = -ESRCH;
+			pr_warn("usdt: failed to find ELF program segment for '%s:%s' in '%s' at IP 0x%lx\n",
+				usdt_provider, usdt_name, path, usdt_abs_ip);
+			goto err_out;
+		}
+		if (!seg->is_exec) {
+			err = -ESRCH;
+			pr_warn("usdt: matched ELF binary '%s' segment [0x%lx, 0x%lx) for '%s:%s' at IP 0x%lx is not executable\n",
+				path, seg->start, seg->end, usdt_provider, usdt_name,
+				usdt_abs_ip);
+			goto err_out;
+		}
+		/* translate from virtual address to file offset */
+		usdt_rel_ip = usdt_abs_ip - seg->start + seg->offset;
+
+		if (ehdr.e_type == ET_DYN && !man->has_bpf_cookie) {
+			/* If we don't have BPF cookie support but need to
+			 * attach to a shared library, we'll need to know and
+			 * record absolute addresses of attach points due to
+			 * the need to lookup USDT spec by absolute IP of
+			 * triggered uprobe. Doing this resolution is only
+			 * possible when we have a specific PID of the process
+			 * that's using specified shared library. BPF cookie
+			 * removes the absolute address limitation as we don't
+			 * need to do this lookup (we just use BPF cookie as
+			 * an index of USDT spec), so for newer kernels with
+			 * BPF cookie support libbpf supports USDT attachment
+			 * to shared libraries with no PID filter.
+			 */
+			if (pid < 0) {
+				pr_warn("usdt: attaching to shared libraries without specific PID is not supported on current kernel\n");
+				err = -ENOTSUP;
+				goto err_out;
+			}
+
+			/* vma_segs are lazily initialized only if necessary */
+			if (vma_seg_cnt == 0) {
+				err = parse_vma_segs(pid, path, &vma_segs, &vma_seg_cnt);
+				if (err) {
+					pr_warn("usdt: failed to get memory segments in PID %d for shared library '%s': %d\n",
+						pid, path, err);
+					goto err_out;
+				}
+			}
+
+			seg = find_vma_seg(vma_segs, vma_seg_cnt, usdt_rel_ip);
+			if (!seg) {
+				err = -ESRCH;
+				pr_warn("usdt: failed to find shared lib memory segment for '%s:%s' in '%s' at relative IP 0x%lx\n",
+					usdt_provider, usdt_name, path, usdt_rel_ip);
+				goto err_out;
+			}
+
+			usdt_abs_ip = seg->start - seg->offset + usdt_rel_ip;
+		}
+
+		pr_debug("usdt: probe for '%s:%s' in %s '%s': addr 0x%lx base 0x%lx (resolved abs_ip 0x%lx rel_ip 0x%lx) args '%s' in segment [0x%lx, 0x%lx) at offset 0x%lx\n",
+			 usdt_provider, usdt_name, ehdr.e_type == ET_EXEC ? "exec" : "lib ", path,
+			 note.loc_addr, note.base_addr, usdt_abs_ip, usdt_rel_ip, note.args,
+			 seg ? seg->start : 0, seg ? seg->end : 0, seg ? seg->offset : 0);
+
+		/* Adjust semaphore address to be a file offset */
+		if (note.sema_addr) {
+			if (!man->has_sema_refcnt) {
+				pr_warn("usdt: kernel doesn't support USDT semaphore refcounting for '%s:%s' in '%s'\n",
+					usdt_provider, usdt_name, path);
+				err = -ENOTSUP;
+				goto err_out;
+			}
+
+			seg = find_elf_seg(segs, seg_cnt, note.sema_addr);
+			if (!seg) {
+				err = -ESRCH;
+				pr_warn("usdt: failed to find ELF loadable segment with semaphore of '%s:%s' in '%s' at 0x%lx\n",
+					usdt_provider, usdt_name, path, note.sema_addr);
+				goto err_out;
+			}
+			if (seg->is_exec) {
+				err = -ESRCH;
+				pr_warn("usdt: matched ELF binary '%s' segment [0x%lx, 0x%lx] for semaphore of '%s:%s' at 0x%lx is executable\n",
+					path, seg->start, seg->end, usdt_provider, usdt_name,
+					note.sema_addr);
+				goto err_out;
+			}
+
+			usdt_sema_off = note.sema_addr - seg->start + seg->offset;
+
+			pr_debug("usdt: sema  for '%s:%s' in %s '%s': addr 0x%lx base 0x%lx (resolved 0x%lx) in segment [0x%lx, 0x%lx] at offset 0x%lx\n",
+				 usdt_provider, usdt_name, ehdr.e_type == ET_EXEC ? "exec" : "lib ",
+				 path, note.sema_addr, note.base_addr, usdt_sema_off,
+				 seg->start, seg->end, seg->offset);
+		}
+
+		/* Record adjusted addresses and offsets and parse USDT spec */
+		tmp = libbpf_reallocarray(targets, target_cnt + 1, sizeof(*targets));
+		if (!tmp) {
+			err = -ENOMEM;
+			goto err_out;
+		}
+		targets = tmp;
+
+		target = &targets[target_cnt];
+		memset(target, 0, sizeof(*target));
+
+		target->abs_ip = usdt_abs_ip;
+		target->rel_ip = usdt_rel_ip;
+		target->sema_off = usdt_sema_off;
+
+		/* notes.args references strings from Elf itself, so they can
+		 * be referenced safely until elf_end() call
+		 */
+		target->spec_str = note.args;
+
+		err = parse_usdt_spec(&target->spec, &note, usdt_cookie);
+		if (err)
+			goto err_out;
+
+		target_cnt++;
+	}
+
+	*out_targets = targets;
+	*out_target_cnt = target_cnt;
+	err = target_cnt;
+
+err_out:
+	free(segs);
+	free(vma_segs);
+	if (err < 0)
+		free(targets);
+	return err;
+}
+
+struct bpf_link_usdt {
+	struct bpf_link link;
+
+	struct usdt_manager *usdt_man;
+
+	size_t spec_cnt;
+	int *spec_ids;
+
+	size_t uprobe_cnt;
+	struct {
+		long abs_ip;
+		struct bpf_link *link;
+	} *uprobes;
+};
+
+static int bpf_link_usdt_detach(struct bpf_link *link)
+{
+	struct bpf_link_usdt *usdt_link = container_of(link, struct bpf_link_usdt, link);
+	struct usdt_manager *man = usdt_link->usdt_man;
+	int i;
+
+	for (i = 0; i < usdt_link->uprobe_cnt; i++) {
+		/* detach underlying uprobe link */
+		bpf_link__destroy(usdt_link->uprobes[i].link);
+		/* there is no need to update specs map because it will be
+		 * unconditionally overwritten on subsequent USDT attaches,
+		 * but if BPF cookies are not used we need to remove entry
+		 * from ip_to_spec_id map, otherwise we'll run into false
+		 * conflicting IP errors
+		 */
+		if (!man->has_bpf_cookie) {
+			/* not much we can do about errors here */
+			(void)bpf_map_delete_elem(bpf_map__fd(man->ip_to_spec_id_map),
+						  &usdt_link->uprobes[i].abs_ip);
+		}
+	}
+
+	/* try to return the list of previously used spec IDs to usdt_manager
+	 * for future reuse for subsequent USDT attaches
+	 */
+	if (!man->free_spec_ids) {
+		/* if there were no free spec IDs yet, just transfer our IDs */
+		man->free_spec_ids = usdt_link->spec_ids;
+		man->free_spec_cnt = usdt_link->spec_cnt;
+		usdt_link->spec_ids = NULL;
+	} else {
+		/* otherwise concat IDs */
+		size_t new_cnt = man->free_spec_cnt + usdt_link->spec_cnt;
+		int *new_free_ids;
+
+		new_free_ids = libbpf_reallocarray(man->free_spec_ids, new_cnt,
+						   sizeof(*new_free_ids));
+		/* If we couldn't resize free_spec_ids, we'll just leak
+		 * a bunch of free IDs; this is very unlikely to happen and if
+		 * system is so exhausted on memory, it's the least of user's
+		 * concerns, probably.
+		 * So just do our best here to return those IDs to usdt_manager.
+		 */
+		if (new_free_ids) {
+			memcpy(new_free_ids + man->free_spec_cnt, usdt_link->spec_ids,
+			       usdt_link->spec_cnt * sizeof(*usdt_link->spec_ids));
+			man->free_spec_ids = new_free_ids;
+			man->free_spec_cnt = new_cnt;
+		}
+	}
+
+	return 0;
+}
+
+static void bpf_link_usdt_dealloc(struct bpf_link *link)
+{
+	struct bpf_link_usdt *usdt_link = container_of(link, struct bpf_link_usdt, link);
+
+	free(usdt_link->spec_ids);
+	free(usdt_link->uprobes);
+	free(usdt_link);
+}
+
+static size_t specs_hash_fn(long key, void *ctx)
+{
+	return str_hash((char *)key);
+}
+
+static bool specs_equal_fn(long key1, long key2, void *ctx)
+{
+	return strcmp((char *)key1, (char *)key2) == 0;
+}
+
+static int allocate_spec_id(struct usdt_manager *man, struct hashmap *specs_hash,
+			    struct bpf_link_usdt *link, struct usdt_target *target,
+			    int *spec_id, bool *is_new)
+{
+	long tmp;
+	void *new_ids;
+	int err;
+
+	/* check if we already allocated spec ID for this spec string */
+	if (hashmap__find(specs_hash, target->spec_str, &tmp)) {
+		*spec_id = tmp;
+		*is_new = false;
+		return 0;
+	}
+
+	/* otherwise it's a new ID that needs to be set up in specs map and
+	 * returned back to usdt_manager when USDT link is detached
+	 */
+	new_ids = libbpf_reallocarray(link->spec_ids, link->spec_cnt + 1, sizeof(*link->spec_ids));
+	if (!new_ids)
+		return -ENOMEM;
+	link->spec_ids = new_ids;
+
+	/* get next free spec ID, giving preference to free list, if not empty */
+	if (man->free_spec_cnt) {
+		*spec_id = man->free_spec_ids[man->free_spec_cnt - 1];
+
+		/* cache spec ID for current spec string for future lookups */
+		err = hashmap__add(specs_hash, target->spec_str, *spec_id);
+		if (err)
+			 return err;
+
+		man->free_spec_cnt--;
+	} else {
+		/* don't allocate spec ID bigger than what fits in specs map */
+		if (man->next_free_spec_id >= bpf_map__max_entries(man->specs_map))
+			return -E2BIG;
+
+		*spec_id = man->next_free_spec_id;
+
+		/* cache spec ID for current spec string for future lookups */
+		err = hashmap__add(specs_hash, target->spec_str, *spec_id);
+		if (err)
+			 return err;
+
+		man->next_free_spec_id++;
+	}
+
+	/* remember new spec ID in the link for later return back to free list on detach */
+	link->spec_ids[link->spec_cnt] = *spec_id;
+	link->spec_cnt++;
+	*is_new = true;
+	return 0;
+}
+
+struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct bpf_program *prog,
+					  pid_t pid, const char *path,
+					  const char *usdt_provider, const char *usdt_name,
+					  __u64 usdt_cookie)
+{
+	int i, fd, err, spec_map_fd, ip_map_fd;
+	LIBBPF_OPTS(bpf_uprobe_opts, opts);
+	struct hashmap *specs_hash = NULL;
+	struct bpf_link_usdt *link = NULL;
+	struct usdt_target *targets = NULL;
+	size_t target_cnt;
+	Elf *elf;
+
+	spec_map_fd = bpf_map__fd(man->specs_map);
+	ip_map_fd = bpf_map__fd(man->ip_to_spec_id_map);
+
+	/* TODO: perform path resolution similar to uprobe's */
+	fd = open(path, O_RDONLY);
+	if (fd < 0) {
+		err = -errno;
+		pr_warn("usdt: failed to open ELF binary '%s': %d\n", path, err);
+		return libbpf_err_ptr(err);
+	}
+
+	elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+	if (!elf) {
+		err = -EBADF;
+		pr_warn("usdt: failed to parse ELF binary '%s': %s\n", path, elf_errmsg(-1));
+		goto err_out;
+	}
+
+	err = sanity_check_usdt_elf(elf, path);
+	if (err)
+		goto err_out;
+
+	/* normalize PID filter */
+	if (pid < 0)
+		pid = -1;
+	else if (pid == 0)
+		pid = getpid();
+
+	/* discover USDT in given binary, optionally limiting
+	 * activations to a given PID, if pid > 0
+	 */
+	err = collect_usdt_targets(man, elf, path, pid, usdt_provider, usdt_name,
+				   usdt_cookie, &targets, &target_cnt);
+	if (err <= 0) {
+		err = (err == 0) ? -ENOENT : err;
+		goto err_out;
+	}
+
+	specs_hash = hashmap__new(specs_hash_fn, specs_equal_fn, NULL);
+	if (IS_ERR(specs_hash)) {
+		err = PTR_ERR(specs_hash);
+		goto err_out;
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	link->usdt_man = man;
+	link->link.detach = &bpf_link_usdt_detach;
+	link->link.dealloc = &bpf_link_usdt_dealloc;
+
+	link->uprobes = calloc(target_cnt, sizeof(*link->uprobes));
+	if (!link->uprobes) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	for (i = 0; i < target_cnt; i++) {
+		struct usdt_target *target = &targets[i];
+		struct bpf_link *uprobe_link;
+		bool is_new;
+		int spec_id;
+
+		/* Spec ID can be either reused or newly allocated. If it is
+		 * newly allocated, we'll need to fill out spec map, otherwise
+		 * entire spec should be valid and can be just used by a new
+		 * uprobe. We reuse spec when USDT arg spec is identical. We
+		 * also never share specs between two different USDT
+		 * attachments ("links"), so all the reused specs already
+		 * share USDT cookie value implicitly.
+		 */
+		err = allocate_spec_id(man, specs_hash, link, target, &spec_id, &is_new);
+		if (err)
+			goto err_out;
+
+		if (is_new && bpf_map_update_elem(spec_map_fd, &spec_id, &target->spec, BPF_ANY)) {
+			err = -errno;
+			pr_warn("usdt: failed to set USDT spec #%d for '%s:%s' in '%s': %d\n",
+				spec_id, usdt_provider, usdt_name, path, err);
+			goto err_out;
+		}
+		if (!man->has_bpf_cookie &&
+		    bpf_map_update_elem(ip_map_fd, &target->abs_ip, &spec_id, BPF_NOEXIST)) {
+			err = -errno;
+			if (err == -EEXIST) {
+				pr_warn("usdt: IP collision detected for spec #%d for '%s:%s' in '%s'\n",
+				        spec_id, usdt_provider, usdt_name, path);
+			} else {
+				pr_warn("usdt: failed to map IP 0x%lx to spec #%d for '%s:%s' in '%s': %d\n",
+					target->abs_ip, spec_id, usdt_provider, usdt_name,
+					path, err);
+			}
+			goto err_out;
+		}
+
+		opts.ref_ctr_offset = target->sema_off;
+		opts.bpf_cookie = man->has_bpf_cookie ? spec_id : 0;
+		uprobe_link = bpf_program__attach_uprobe_opts(prog, pid, path,
+							      target->rel_ip, &opts);
+		err = libbpf_get_error(uprobe_link);
+		if (err) {
+			pr_warn("usdt: failed to attach uprobe #%d for '%s:%s' in '%s': %d\n",
+				i, usdt_provider, usdt_name, path, err);
+			goto err_out;
+		}
+
+		link->uprobes[i].link = uprobe_link;
+		link->uprobes[i].abs_ip = target->abs_ip;
+		link->uprobe_cnt++;
+	}
+
+	free(targets);
+	hashmap__free(specs_hash);
+	elf_end(elf);
+	close(fd);
+
+	return &link->link;
+
+err_out:
+	if (link)
+		bpf_link__destroy(&link->link);
+	free(targets);
+	hashmap__free(specs_hash);
+	if (elf)
+		elf_end(elf);
+	close(fd);
+	return libbpf_err_ptr(err);
+}
+
+/* Parse out USDT ELF note from '.note.stapsdt' section.
+ * Logic inspired by perf's code.
+ */
+static int parse_usdt_note(Elf *elf, const char *path, GElf_Nhdr *nhdr,
+			   const char *data, size_t name_off, size_t desc_off,
+			   struct usdt_note *note)
+{
+	const char *provider, *name, *args;
+	long addrs[3];
+	size_t len;
+
+	/* sanity check USDT note name and type first */
+	if (strncmp(data + name_off, USDT_NOTE_NAME, nhdr->n_namesz) != 0)
+		return -EINVAL;
+	if (nhdr->n_type != USDT_NOTE_TYPE)
+		return -EINVAL;
+
+	/* sanity check USDT note contents ("description" in ELF terminology) */
+	len = nhdr->n_descsz;
+	data = data + desc_off;
+
+	/* +3 is the very minimum required to store three empty strings */
+	if (len < sizeof(addrs) + 3)
+		return -EINVAL;
+
+	/* get location, base, and semaphore addrs */
+	memcpy(&addrs, data, sizeof(addrs));
+
+	/* parse string fields: provider, name, args */
+	provider = data + sizeof(addrs);
+
+	name = (const char *)memchr(provider, '\0', data + len - provider);
+	if (!name) /* non-zero-terminated provider */
+		return -EINVAL;
+	name++;
+	if (name >= data + len || *name == '\0') /* missing or empty name */
+		return -EINVAL;
+
+	args = memchr(name, '\0', data + len - name);
+	if (!args) /* non-zero-terminated name */
+		return -EINVAL;
+	++args;
+	if (args >= data + len) /* missing arguments spec */
+		return -EINVAL;
+
+	note->provider = provider;
+	note->name = name;
+	if (*args == '\0' || *args == ':')
+		note->args = "";
+	else
+		note->args = args;
+	note->loc_addr = addrs[0];
+	note->base_addr = addrs[1];
+	note->sema_addr = addrs[2];
+
+	return 0;
+}
+
+static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg);
+
+static int parse_usdt_spec(struct usdt_spec *spec, const struct usdt_note *note, __u64 usdt_cookie)
+{
+	const char *s;
+	int len;
+
+	spec->usdt_cookie = usdt_cookie;
+	spec->arg_cnt = 0;
+
+	s = note->args;
+	while (s[0]) {
+		if (spec->arg_cnt >= USDT_MAX_ARG_CNT) {
+			pr_warn("usdt: too many USDT arguments (> %d) for '%s:%s' with args spec '%s'\n",
+				USDT_MAX_ARG_CNT, note->provider, note->name, note->args);
+			return -E2BIG;
+		}
+
+		len = parse_usdt_arg(s, spec->arg_cnt, &spec->args[spec->arg_cnt]);
+		if (len < 0)
+			return len;
+
+		s += len;
+		spec->arg_cnt++;
+	}
+
+	return 0;
+}
+
+/* Architecture-specific logic for parsing USDT argument location specs */
+
+#if defined(__x86_64__) || defined(__i386__)
+
+static int calc_pt_regs_off(const char *reg_name)
+{
+	static struct {
+		const char *names[4];
+		size_t pt_regs_off;
+	} reg_map[] = {
+#ifdef __x86_64__
+#define reg_off(reg64, reg32) offsetof(struct pt_regs, reg64)
+#else
+#define reg_off(reg64, reg32) offsetof(struct pt_regs, reg32)
+#endif
+		{ {"rip", "eip", "", ""}, reg_off(rip, eip) },
+		{ {"rax", "eax", "ax", "al"}, reg_off(rax, eax) },
+		{ {"rbx", "ebx", "bx", "bl"}, reg_off(rbx, ebx) },
+		{ {"rcx", "ecx", "cx", "cl"}, reg_off(rcx, ecx) },
+		{ {"rdx", "edx", "dx", "dl"}, reg_off(rdx, edx) },
+		{ {"rsi", "esi", "si", "sil"}, reg_off(rsi, esi) },
+		{ {"rdi", "edi", "di", "dil"}, reg_off(rdi, edi) },
+		{ {"rbp", "ebp", "bp", "bpl"}, reg_off(rbp, ebp) },
+		{ {"rsp", "esp", "sp", "spl"}, reg_off(rsp, esp) },
+#undef reg_off
+#ifdef __x86_64__
+		{ {"r8", "r8d", "r8w", "r8b"}, offsetof(struct pt_regs, r8) },
+		{ {"r9", "r9d", "r9w", "r9b"}, offsetof(struct pt_regs, r9) },
+		{ {"r10", "r10d", "r10w", "r10b"}, offsetof(struct pt_regs, r10) },
+		{ {"r11", "r11d", "r11w", "r11b"}, offsetof(struct pt_regs, r11) },
+		{ {"r12", "r12d", "r12w", "r12b"}, offsetof(struct pt_regs, r12) },
+		{ {"r13", "r13d", "r13w", "r13b"}, offsetof(struct pt_regs, r13) },
+		{ {"r14", "r14d", "r14w", "r14b"}, offsetof(struct pt_regs, r14) },
+		{ {"r15", "r15d", "r15w", "r15b"}, offsetof(struct pt_regs, r15) },
+#endif
+	};
+	int i, j;
+
+	for (i = 0; i < ARRAY_SIZE(reg_map); i++) {
+		for (j = 0; j < ARRAY_SIZE(reg_map[i].names); j++) {
+			if (strcmp(reg_name, reg_map[i].names[j]) == 0)
+				return reg_map[i].pt_regs_off;
+		}
+	}
+
+	pr_warn("usdt: unrecognized register '%s'\n", reg_name);
+	return -ENOENT;
+}
+
+static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
+{
+	char reg_name[16];
+	int arg_sz, len, reg_off;
+	long off;
+
+	if (sscanf(arg_str, " %d @ %ld ( %%%15[^)] ) %n", &arg_sz, &off, reg_name, &len) == 3) {
+		/* Memory dereference case, e.g., -4@-20(%rbp) */
+		arg->arg_type = USDT_ARG_REG_DEREF;
+		arg->val_off = off;
+		reg_off = calc_pt_regs_off(reg_name);
+		if (reg_off < 0)
+			return reg_off;
+		arg->reg_off = reg_off;
+	} else if (sscanf(arg_str, " %d @ ( %%%15[^)] ) %n", &arg_sz, reg_name, &len) == 2) {
+		/* Memory dereference case without offset, e.g., 8@(%rsp) */
+		arg->arg_type = USDT_ARG_REG_DEREF;
+		arg->val_off = 0;
+		reg_off = calc_pt_regs_off(reg_name);
+		if (reg_off < 0)
+			return reg_off;
+		arg->reg_off = reg_off;
+	} else if (sscanf(arg_str, " %d @ %%%15s %n", &arg_sz, reg_name, &len) == 2) {
+		/* Register read case, e.g., -4@%eax */
+		arg->arg_type = USDT_ARG_REG;
+		arg->val_off = 0;
+
+		reg_off = calc_pt_regs_off(reg_name);
+		if (reg_off < 0)
+			return reg_off;
+		arg->reg_off = reg_off;
+	} else if (sscanf(arg_str, " %d @ $%ld %n", &arg_sz, &off, &len) == 2) {
+		/* Constant value case, e.g., 4@$71 */
+		arg->arg_type = USDT_ARG_CONST;
+		arg->val_off = off;
+		arg->reg_off = 0;
+	} else {
+		pr_warn("usdt: unrecognized arg #%d spec '%s'\n", arg_num, arg_str);
+		return -EINVAL;
+	}
+
+	arg->arg_signed = arg_sz < 0;
+	if (arg_sz < 0)
+		arg_sz = -arg_sz;
+
+	switch (arg_sz) {
+	case 1: case 2: case 4: case 8:
+		arg->arg_bitshift = 64 - arg_sz * 8;
+		break;
+	default:
+		pr_warn("usdt: unsupported arg #%d (spec '%s') size: %d\n",
+			arg_num, arg_str, arg_sz);
+		return -EINVAL;
+	}
+
+	return len;
+}
+
+#elif defined(__s390x__)
+
+/* Do not support __s390__ for now, since user_pt_regs is broken with -m31. */
+
+static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
+{
+	unsigned int reg;
+	int arg_sz, len;
+	long off;
+
+	if (sscanf(arg_str, " %d @ %ld ( %%r%u ) %n", &arg_sz, &off, &reg, &len) == 3) {
+		/* Memory dereference case, e.g., -2@-28(%r15) */
+		arg->arg_type = USDT_ARG_REG_DEREF;
+		arg->val_off = off;
+		if (reg > 15) {
+			pr_warn("usdt: unrecognized register '%%r%u'\n", reg);
+			return -EINVAL;
+		}
+		arg->reg_off = offsetof(user_pt_regs, gprs[reg]);
+	} else if (sscanf(arg_str, " %d @ %%r%u %n", &arg_sz, &reg, &len) == 2) {
+		/* Register read case, e.g., -8@%r0 */
+		arg->arg_type = USDT_ARG_REG;
+		arg->val_off = 0;
+		if (reg > 15) {
+			pr_warn("usdt: unrecognized register '%%r%u'\n", reg);
+			return -EINVAL;
+		}
+		arg->reg_off = offsetof(user_pt_regs, gprs[reg]);
+	} else if (sscanf(arg_str, " %d @ %ld %n", &arg_sz, &off, &len) == 2) {
+		/* Constant value case, e.g., 4@71 */
+		arg->arg_type = USDT_ARG_CONST;
+		arg->val_off = off;
+		arg->reg_off = 0;
+	} else {
+		pr_warn("usdt: unrecognized arg #%d spec '%s'\n", arg_num, arg_str);
+		return -EINVAL;
+	}
+
+	arg->arg_signed = arg_sz < 0;
+	if (arg_sz < 0)
+		arg_sz = -arg_sz;
+
+	switch (arg_sz) {
+	case 1: case 2: case 4: case 8:
+		arg->arg_bitshift = 64 - arg_sz * 8;
+		break;
+	default:
+		pr_warn("usdt: unsupported arg #%d (spec '%s') size: %d\n",
+			arg_num, arg_str, arg_sz);
+		return -EINVAL;
+	}
+
+	return len;
+}
+
+#elif defined(__aarch64__)
+
+static int calc_pt_regs_off(const char *reg_name)
+{
+	int reg_num;
+
+	if (sscanf(reg_name, "x%d", &reg_num) == 1) {
+		if (reg_num >= 0 && reg_num < 31)
+			return offsetof(struct user_pt_regs, regs[reg_num]);
+	} else if (strcmp(reg_name, "sp") == 0) {
+		return offsetof(struct user_pt_regs, sp);
+	}
+	pr_warn("usdt: unrecognized register '%s'\n", reg_name);
+	return -ENOENT;
+}
+
+static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
+{
+	char reg_name[16];
+	int arg_sz, len, reg_off;
+	long off;
+
+	if (sscanf(arg_str, " %d @ \[ %15[a-z0-9], %ld ] %n", &arg_sz, reg_name, &off, &len) == 3) {
+		/* Memory dereference case, e.g., -4@[sp, 96] */
+		arg->arg_type = USDT_ARG_REG_DEREF;
+		arg->val_off = off;
+		reg_off = calc_pt_regs_off(reg_name);
+		if (reg_off < 0)
+			return reg_off;
+		arg->reg_off = reg_off;
+	} else if (sscanf(arg_str, " %d @ \[ %15[a-z0-9] ] %n", &arg_sz, reg_name, &len) == 2) {
+		/* Memory dereference case, e.g., -4@[sp] */
+		arg->arg_type = USDT_ARG_REG_DEREF;
+		arg->val_off = 0;
+		reg_off = calc_pt_regs_off(reg_name);
+		if (reg_off < 0)
+			return reg_off;
+		arg->reg_off = reg_off;
+	} else if (sscanf(arg_str, " %d @ %ld %n", &arg_sz, &off, &len) == 2) {
+		/* Constant value case, e.g., 4@5 */
+		arg->arg_type = USDT_ARG_CONST;
+		arg->val_off = off;
+		arg->reg_off = 0;
+	} else if (sscanf(arg_str, " %d @ %15[a-z0-9] %n", &arg_sz, reg_name, &len) == 2) {
+		/* Register read case, e.g., -8@x4 */
+		arg->arg_type = USDT_ARG_REG;
+		arg->val_off = 0;
+		reg_off = calc_pt_regs_off(reg_name);
+		if (reg_off < 0)
+			return reg_off;
+		arg->reg_off = reg_off;
+	} else {
+		pr_warn("usdt: unrecognized arg #%d spec '%s'\n", arg_num, arg_str);
+		return -EINVAL;
+	}
+
+	arg->arg_signed = arg_sz < 0;
+	if (arg_sz < 0)
+		arg_sz = -arg_sz;
+
+	switch (arg_sz) {
+	case 1: case 2: case 4: case 8:
+		arg->arg_bitshift = 64 - arg_sz * 8;
+		break;
+	default:
+		pr_warn("usdt: unsupported arg #%d (spec '%s') size: %d\n",
+			arg_num, arg_str, arg_sz);
+		return -EINVAL;
+	}
+
+	return len;
+}
+
+#elif defined(__riscv)
+
+static int calc_pt_regs_off(const char *reg_name)
+{
+	static struct {
+		const char *name;
+		size_t pt_regs_off;
+	} reg_map[] = {
+		{ "ra", offsetof(struct user_regs_struct, ra) },
+		{ "sp", offsetof(struct user_regs_struct, sp) },
+		{ "gp", offsetof(struct user_regs_struct, gp) },
+		{ "tp", offsetof(struct user_regs_struct, tp) },
+		{ "a0", offsetof(struct user_regs_struct, a0) },
+		{ "a1", offsetof(struct user_regs_struct, a1) },
+		{ "a2", offsetof(struct user_regs_struct, a2) },
+		{ "a3", offsetof(struct user_regs_struct, a3) },
+		{ "a4", offsetof(struct user_regs_struct, a4) },
+		{ "a5", offsetof(struct user_regs_struct, a5) },
+		{ "a6", offsetof(struct user_regs_struct, a6) },
+		{ "a7", offsetof(struct user_regs_struct, a7) },
+		{ "s0", offsetof(struct user_regs_struct, s0) },
+		{ "s1", offsetof(struct user_regs_struct, s1) },
+		{ "s2", offsetof(struct user_regs_struct, s2) },
+		{ "s3", offsetof(struct user_regs_struct, s3) },
+		{ "s4", offsetof(struct user_regs_struct, s4) },
+		{ "s5", offsetof(struct user_regs_struct, s5) },
+		{ "s6", offsetof(struct user_regs_struct, s6) },
+		{ "s7", offsetof(struct user_regs_struct, s7) },
+		{ "s8", offsetof(struct user_regs_struct, rv_s8) },
+		{ "s9", offsetof(struct user_regs_struct, s9) },
+		{ "s10", offsetof(struct user_regs_struct, s10) },
+		{ "s11", offsetof(struct user_regs_struct, s11) },
+		{ "t0", offsetof(struct user_regs_struct, t0) },
+		{ "t1", offsetof(struct user_regs_struct, t1) },
+		{ "t2", offsetof(struct user_regs_struct, t2) },
+		{ "t3", offsetof(struct user_regs_struct, t3) },
+		{ "t4", offsetof(struct user_regs_struct, t4) },
+		{ "t5", offsetof(struct user_regs_struct, t5) },
+		{ "t6", offsetof(struct user_regs_struct, t6) },
+	};
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(reg_map); i++) {
+		if (strcmp(reg_name, reg_map[i].name) == 0)
+			return reg_map[i].pt_regs_off;
+	}
+
+	pr_warn("usdt: unrecognized register '%s'\n", reg_name);
+	return -ENOENT;
+}
+
+static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
+{
+	char reg_name[16];
+	int arg_sz, len, reg_off;
+	long off;
+
+	if (sscanf(arg_str, " %d @ %ld ( %15[a-z0-9] ) %n", &arg_sz, &off, reg_name, &len) == 3) {
+		/* Memory dereference case, e.g., -8@-88(s0) */
+		arg->arg_type = USDT_ARG_REG_DEREF;
+		arg->val_off = off;
+		reg_off = calc_pt_regs_off(reg_name);
+		if (reg_off < 0)
+			return reg_off;
+		arg->reg_off = reg_off;
+	} else if (sscanf(arg_str, " %d @ %ld %n", &arg_sz, &off, &len) == 2) {
+		/* Constant value case, e.g., 4@5 */
+		arg->arg_type = USDT_ARG_CONST;
+		arg->val_off = off;
+		arg->reg_off = 0;
+	} else if (sscanf(arg_str, " %d @ %15[a-z0-9] %n", &arg_sz, reg_name, &len) == 2) {
+		/* Register read case, e.g., -8@a1 */
+		arg->arg_type = USDT_ARG_REG;
+		arg->val_off = 0;
+		reg_off = calc_pt_regs_off(reg_name);
+		if (reg_off < 0)
+			return reg_off;
+		arg->reg_off = reg_off;
+	} else {
+		pr_warn("usdt: unrecognized arg #%d spec '%s'\n", arg_num, arg_str);
+		return -EINVAL;
+	}
+
+	arg->arg_signed = arg_sz < 0;
+	if (arg_sz < 0)
+		arg_sz = -arg_sz;
+
+	switch (arg_sz) {
+	case 1: case 2: case 4: case 8:
+		arg->arg_bitshift = 64 - arg_sz * 8;
+		break;
+	default:
+		pr_warn("usdt: unsupported arg #%d (spec '%s') size: %d\n",
+			arg_num, arg_str, arg_sz);
+		return -EINVAL;
+	}
+
+	return len;
+}
+
+#else
+
+static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
+{
+	pr_warn("usdt: libbpf doesn't support USDTs on current architecture\n");
+	return -ENOTSUP;
+}
+
+#endif