Adding upstream version 3.2.6.upstream/3.2.6upstream

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

1 files changed, 6581 insertions, 0 deletions

diff --git a/src/contrib/libbpf/bpf/libbpf.c b/src/contrib/libbpf/bpf/libbpf.c
new file mode 100644
index 0000000..29d8d03
--- /dev/null
+++ b/src/contrib/libbpf/bpf/libbpf.c
@@ -0,0 +1,6581 @@
+// 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 <string.h>
+#include <unistd.h>
+#include <endian.h>
+#include <fcntl.h>
+#include <errno.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/list.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 <libelf.h>
+#include <gelf.h>
+
+#include "libbpf.h"
+#include "bpf.h"
+#include "btf.h"
+#include "str_error.h"
+#include "libbpf_internal.h"
+#include "hashmap.h"
+
+#ifndef EM_BPF
+#define EM_BPF 247
+#endif
+
+#ifndef BPF_FS_MAGIC
+#define BPF_FS_MAGIC		0xcafe4a11
+#endif
+
+/* 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 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;
+
+	if (!__libbpf_pr)
+		return;
+
+	va_start(args, format);
+	__libbpf_pr(level, format, args);
+	va_end(args);
+}
+
+#define STRERR_BUFSIZE  128
+
+#define CHECK_ERR(action, err, out) do {	\
+	err = action;			\
+	if (err)			\
+		goto out;		\
+} while (0)
+
+
+/* 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
+
+#ifdef HAVE_LIBELF_MMAP_SUPPORT
+# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ_MMAP
+#else
+# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ
+#endif
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64) (unsigned long) ptr;
+}
+
+struct bpf_capabilities {
+	/* v4.14: kernel support for program & map names. */
+	__u32 name:1;
+	/* v5.2: kernel support for global data sections. */
+	__u32 global_data:1;
+	/* BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO support */
+	__u32 btf_func:1;
+	/* BTF_KIND_VAR and BTF_KIND_DATASEC support */
+	__u32 btf_datasec:1;
+	/* BPF_F_MMAPABLE is supported for arrays */
+	__u32 array_mmap:1;
+};
+
+/*
+ * bpf_prog should be a better name but it has been used in
+ * linux/filter.h.
+ */
+struct bpf_program {
+	/* Index in elf obj file, for relocation use. */
+	int idx;
+	char *name;
+	int prog_ifindex;
+	char *section_name;
+	/* section_name with / replaced by _; makes recursive pinning
+	 * in bpf_object__pin_programs easier
+	 */
+	char *pin_name;
+	struct bpf_insn *insns;
+	size_t insns_cnt, main_prog_cnt;
+	enum bpf_prog_type type;
+
+	struct reloc_desc {
+		enum {
+			RELO_LD64,
+			RELO_CALL,
+			RELO_DATA,
+		} type;
+		int insn_idx;
+		int map_idx;
+		int sym_off;
+	} *reloc_desc;
+	int nr_reloc;
+	int log_level;
+
+	struct {
+		int nr;
+		int *fds;
+	} instances;
+	bpf_program_prep_t preprocessor;
+
+	struct bpf_object *obj;
+	void *priv;
+	bpf_program_clear_priv_t clear_priv;
+
+	enum bpf_attach_type expected_attach_type;
+	__u32 attach_btf_id;
+	__u32 attach_prog_fd;
+	void *func_info;
+	__u32 func_info_rec_size;
+	__u32 func_info_cnt;
+
+	struct bpf_capabilities *caps;
+
+	void *line_info;
+	__u32 line_info_rec_size;
+	__u32 line_info_cnt;
+	__u32 prog_flags;
+};
+
+enum libbpf_map_type {
+	LIBBPF_MAP_UNSPEC,
+	LIBBPF_MAP_DATA,
+	LIBBPF_MAP_BSS,
+	LIBBPF_MAP_RODATA,
+};
+
+static const char * const libbpf_type_to_btf_name[] = {
+	[LIBBPF_MAP_DATA]	= ".data",
+	[LIBBPF_MAP_BSS]	= ".bss",
+	[LIBBPF_MAP_RODATA]	= ".rodata",
+};
+
+struct bpf_map {
+	int fd;
+	char *name;
+	int sec_idx;
+	size_t sec_offset;
+	int map_ifindex;
+	int inner_map_fd;
+	struct bpf_map_def def;
+	__u32 btf_key_type_id;
+	__u32 btf_value_type_id;
+	void *priv;
+	bpf_map_clear_priv_t clear_priv;
+	enum libbpf_map_type libbpf_type;
+	char *pin_path;
+	bool pinned;
+	bool reused;
+};
+
+struct bpf_secdata {
+	void *rodata;
+	void *data;
+};
+
+static LIST_HEAD(bpf_objects_list);
+
+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;
+	struct bpf_secdata sections;
+
+	bool loaded;
+	bool has_pseudo_calls;
+	bool relaxed_core_relocs;
+
+	/*
+	 * Information when doing elf related work. Only valid if fd
+	 * is valid.
+	 */
+	struct {
+		int fd;
+		const void *obj_buf;
+		size_t obj_buf_sz;
+		Elf *elf;
+		GElf_Ehdr ehdr;
+		Elf_Data *symbols;
+		Elf_Data *data;
+		Elf_Data *rodata;
+		Elf_Data *bss;
+		size_t strtabidx;
+		struct {
+			GElf_Shdr shdr;
+			Elf_Data *data;
+		} *reloc_sects;
+		int nr_reloc_sects;
+		int maps_shndx;
+		int btf_maps_shndx;
+		int text_shndx;
+		int data_shndx;
+		int rodata_shndx;
+		int bss_shndx;
+	} efile;
+	/*
+	 * All loaded bpf_object is linked in a list, which is
+	 * hidden to caller. bpf_objects__<func> handlers deal with
+	 * all objects.
+	 */
+	struct list_head list;
+
+	struct btf *btf;
+	struct btf_ext *btf_ext;
+
+	void *priv;
+	bpf_object_clear_priv_t clear_priv;
+
+	struct bpf_capabilities caps;
+
+	char path[];
+};
+#define obj_elf_valid(o)	((o)->efile.elf)
+
+void bpf_program__unload(struct bpf_program *prog)
+{
+	int i;
+
+	if (!prog)
+		return;
+
+	/*
+	 * If the object is opened but the program was never loaded,
+	 * it is possible that prog->instances.nr == -1.
+	 */
+	if (prog->instances.nr > 0) {
+		for (i = 0; i < prog->instances.nr; i++)
+			zclose(prog->instances.fds[i]);
+	} else if (prog->instances.nr != -1) {
+		pr_warn("Internal error: instances.nr is %d\n",
+			prog->instances.nr);
+	}
+
+	prog->instances.nr = -1;
+	zfree(&prog->instances.fds);
+
+	zfree(&prog->func_info);
+	zfree(&prog->line_info);
+}
+
+static void bpf_program__exit(struct bpf_program *prog)
+{
+	if (!prog)
+		return;
+
+	if (prog->clear_priv)
+		prog->clear_priv(prog, prog->priv);
+
+	prog->priv = NULL;
+	prog->clear_priv = NULL;
+
+	bpf_program__unload(prog);
+	zfree(&prog->name);
+	zfree(&prog->section_name);
+	zfree(&prog->pin_name);
+	zfree(&prog->insns);
+	zfree(&prog->reloc_desc);
+
+	prog->nr_reloc = 0;
+	prog->insns_cnt = 0;
+	prog->idx = -1;
+}
+
+static char *__bpf_program__pin_name(struct bpf_program *prog)
+{
+	char *name, *p;
+
+	name = p = strdup(prog->section_name);
+	while ((p = strchr(p, '/')))
+		*p = '_';
+
+	return name;
+}
+
+static int
+bpf_program__init(void *data, size_t size, char *section_name, int idx,
+		  struct bpf_program *prog)
+{
+	const size_t bpf_insn_sz = sizeof(struct bpf_insn);
+
+	if (size == 0 || size % bpf_insn_sz) {
+		pr_warn("corrupted section '%s', size: %zu\n",
+			section_name, size);
+		return -EINVAL;
+	}
+
+	memset(prog, 0, sizeof(*prog));
+
+	prog->section_name = strdup(section_name);
+	if (!prog->section_name) {
+		pr_warn("failed to alloc name for prog under section(%d) %s\n",
+			idx, section_name);
+		goto errout;
+	}
+
+	prog->pin_name = __bpf_program__pin_name(prog);
+	if (!prog->pin_name) {
+		pr_warn("failed to alloc pin name for prog under section(%d) %s\n",
+			idx, section_name);
+		goto errout;
+	}
+
+	prog->insns = malloc(size);
+	if (!prog->insns) {
+		pr_warn("failed to alloc insns for prog under section %s\n",
+			section_name);
+		goto errout;
+	}
+	prog->insns_cnt = size / bpf_insn_sz;
+	memcpy(prog->insns, data, size);
+	prog->idx = idx;
+	prog->instances.fds = NULL;
+	prog->instances.nr = -1;
+	prog->type = BPF_PROG_TYPE_UNSPEC;
+
+	return 0;
+errout:
+	bpf_program__exit(prog);
+	return -ENOMEM;
+}
+
+static int
+bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
+			char *section_name, int idx)
+{
+	struct bpf_program prog, *progs;
+	int nr_progs, err;
+
+	err = bpf_program__init(data, size, section_name, idx, &prog);
+	if (err)
+		return err;
+
+	prog.caps = &obj->caps;
+	progs = obj->programs;
+	nr_progs = obj->nr_programs;
+
+	progs = reallocarray(progs, nr_progs + 1, sizeof(progs[0]));
+	if (!progs) {
+		/*
+		 * In this case the original obj->programs
+		 * is still valid, so don't need special treat for
+		 * bpf_close_object().
+		 */
+		pr_warn("failed to alloc a new program under section '%s'\n",
+			section_name);
+		bpf_program__exit(&prog);
+		return -ENOMEM;
+	}
+
+	pr_debug("found program %s\n", prog.section_name);
+	obj->programs = progs;
+	obj->nr_programs = nr_progs + 1;
+	prog.obj = obj;
+	progs[nr_progs] = prog;
+	return 0;
+}
+
+static int
+bpf_object__init_prog_names(struct bpf_object *obj)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	struct bpf_program *prog;
+	size_t pi, si;
+
+	for (pi = 0; pi < obj->nr_programs; pi++) {
+		const char *name = NULL;
+
+		prog = &obj->programs[pi];
+
+		for (si = 0; si < symbols->d_size / sizeof(GElf_Sym) && !name;
+		     si++) {
+			GElf_Sym sym;
+
+			if (!gelf_getsym(symbols, si, &sym))
+				continue;
+			if (sym.st_shndx != prog->idx)
+				continue;
+			if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL)
+				continue;
+
+			name = elf_strptr(obj->efile.elf,
+					  obj->efile.strtabidx,
+					  sym.st_name);
+			if (!name) {
+				pr_warn("failed to get sym name string for prog %s\n",
+					prog->section_name);
+				return -LIBBPF_ERRNO__LIBELF;
+			}
+		}
+
+		if (!name && prog->idx == obj->efile.text_shndx)
+			name = ".text";
+
+		if (!name) {
+			pr_warn("failed to find sym for prog %s\n",
+				prog->section_name);
+			return -EINVAL;
+		}
+
+		prog->name = strdup(name);
+		if (!prog->name) {
+			pr_warn("failed to allocate memory for prog sym %s\n",
+				name);
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
+static __u32 get_kernel_version(void)
+{
+	__u32 major, minor, patch;
+	struct utsname info;
+
+	uname(&info);
+	if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3)
+		return 0;
+	return KERNEL_VERSION(major, minor, patch);
+}
+
+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) {
+		strncpy(obj->name, obj_name, sizeof(obj->name) - 1);
+		obj->name[sizeof(obj->name) - 1] = 0;
+	} else {
+		/* Using basename() GNU version which doesn't modify arg. */
+		strncpy(obj->name, basename((void *)path),
+			sizeof(obj->name) - 1);
+		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.maps_shndx = -1;
+	obj->efile.btf_maps_shndx = -1;
+	obj->efile.data_shndx = -1;
+	obj->efile.rodata_shndx = -1;
+	obj->efile.bss_shndx = -1;
+
+	obj->kern_version = get_kernel_version();
+	obj->loaded = false;
+
+	INIT_LIST_HEAD(&obj->list);
+	list_add(&obj->list, &bpf_objects_list);
+	return obj;
+}
+
+static void bpf_object__elf_finish(struct bpf_object *obj)
+{
+	if (!obj_elf_valid(obj))
+		return;
+
+	if (obj->efile.elf) {
+		elf_end(obj->efile.elf);
+		obj->efile.elf = NULL;
+	}
+	obj->efile.symbols = NULL;
+	obj->efile.data = NULL;
+	obj->efile.rodata = NULL;
+	obj->efile.bss = NULL;
+
+	zfree(&obj->efile.reloc_sects);
+	obj->efile.nr_reloc_sects = 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)
+{
+	int err = 0;
+	GElf_Ehdr *ep;
+
+	if (obj_elf_valid(obj)) {
+		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_buffer().
+		 */
+		obj->efile.elf = elf_memory((char *)obj->efile.obj_buf,
+					    obj->efile.obj_buf_sz);
+	} else {
+		obj->efile.fd = open(obj->path, O_RDONLY);
+		if (obj->efile.fd < 0) {
+			char errmsg[STRERR_BUFSIZE], *cp;
+
+			err = -errno;
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+			pr_warn("failed to open %s: %s\n", obj->path, cp);
+			return err;
+		}
+
+		obj->efile.elf = elf_begin(obj->efile.fd,
+					   LIBBPF_ELF_C_READ_MMAP, NULL);
+	}
+
+	if (!obj->efile.elf) {
+		pr_warn("failed to open %s as ELF file\n", obj->path);
+		err = -LIBBPF_ERRNO__LIBELF;
+		goto errout;
+	}
+
+	if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) {
+		pr_warn("failed to get EHDR from %s\n", obj->path);
+		err = -LIBBPF_ERRNO__FORMAT;
+		goto errout;
+	}
+	ep = &obj->efile.ehdr;
+
+	/* Old LLVM set e_machine to EM_NONE */
+	if (ep->e_type != ET_REL ||
+	    (ep->e_machine && ep->e_machine != EM_BPF)) {
+		pr_warn("%s is not an 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 == __LITTLE_ENDIAN
+	if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
+		return 0;
+#elif __BYTE_ORDER == __BIG_ENDIAN
+	if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2MSB)
+		return 0;
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+	pr_warn("endianness mismatch.\n");
+	return -LIBBPF_ERRNO__ENDIAN;
+}
+
+static int
+bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
+{
+	memcpy(obj->license, data, min(size, sizeof(obj->license) - 1));
+	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 (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 int compare_bpf_map(const void *_a, const void *_b)
+{
+	const struct bpf_map *a = _a;
+	const struct bpf_map *b = _b;
+
+	if (a->sec_idx != b->sec_idx)
+		return a->sec_idx - b->sec_idx;
+	return a->sec_offset - b->sec_offset;
+}
+
+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 bpf_object_search_section_size(const struct bpf_object *obj,
+					  const char *name, size_t *d_size)
+{
+	const GElf_Ehdr *ep = &obj->efile.ehdr;
+	Elf *elf = obj->efile.elf;
+	Elf_Scn *scn = NULL;
+	int idx = 0;
+
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		const char *sec_name;
+		Elf_Data *data;
+		GElf_Shdr sh;
+
+		idx++;
+		if (gelf_getshdr(scn, &sh) != &sh) {
+			pr_warn("failed to get section(%d) header from %s\n",
+				idx, obj->path);
+			return -EIO;
+		}
+
+		sec_name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
+		if (!sec_name) {
+			pr_warn("failed to get section(%d) name from %s\n",
+				idx, obj->path);
+			return -EIO;
+		}
+
+		if (strcmp(name, sec_name))
+			continue;
+
+		data = elf_getdata(scn, 0);
+		if (!data) {
+			pr_warn("failed to get section(%d) data from %s(%s)\n",
+				idx, name, obj->path);
+			return -EIO;
+		}
+
+		*d_size = data->d_size;
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+int bpf_object__section_size(const struct bpf_object *obj, const char *name,
+			     __u32 *size)
+{
+	int ret = -ENOENT;
+	size_t d_size;
+
+	*size = 0;
+	if (!name) {
+		return -EINVAL;
+	} else if (!strcmp(name, ".data")) {
+		if (obj->efile.data)
+			*size = obj->efile.data->d_size;
+	} else if (!strcmp(name, ".bss")) {
+		if (obj->efile.bss)
+			*size = obj->efile.bss->d_size;
+	} else if (!strcmp(name, ".rodata")) {
+		if (obj->efile.rodata)
+			*size = obj->efile.rodata->d_size;
+	} else {
+		ret = bpf_object_search_section_size(obj, name, &d_size);
+		if (!ret)
+			*size = d_size;
+	}
+
+	return *size ? 0 : ret;
+}
+
+int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
+				__u32 *off)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	const char *sname;
+	size_t si;
+
+	if (!name || !off)
+		return -EINVAL;
+
+	for (si = 0; si < symbols->d_size / sizeof(GElf_Sym); si++) {
+		GElf_Sym sym;
+
+		if (!gelf_getsym(symbols, si, &sym))
+			continue;
+		if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL ||
+		    GELF_ST_TYPE(sym.st_info) != STT_OBJECT)
+			continue;
+
+		sname = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
+				   sym.st_name);
+		if (!sname) {
+			pr_warn("failed to get sym name string for var %s\n",
+				name);
+			return -EIO;
+		}
+		if (strcmp(name, sname) == 0) {
+			*off = sym.st_value;
+			return 0;
+		}
+	}
+
+	return -ENOENT;
+}
+
+static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
+{
+	struct bpf_map *new_maps;
+	size_t new_cap;
+	int i;
+
+	if (obj->nr_maps < obj->maps_cap)
+		return &obj->maps[obj->nr_maps++];
+
+	new_cap = max((size_t)4, obj->maps_cap * 3 / 2);
+	new_maps = realloc(obj->maps, new_cap * sizeof(*obj->maps));
+	if (!new_maps) {
+		pr_warn("alloc maps for object failed\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	obj->maps_cap = new_cap;
+	obj->maps = new_maps;
+
+	/* zero out new maps */
+	memset(obj->maps + obj->nr_maps, 0,
+	       (obj->maps_cap - obj->nr_maps) * sizeof(*obj->maps));
+	/*
+	 * fill all fd with -1 so won't close incorrect fd (fd=0 is stdin)
+	 * when failure (zclose won't close negative fd)).
+	 */
+	for (i = obj->nr_maps; i < obj->maps_cap; i++) {
+		obj->maps[i].fd = -1;
+		obj->maps[i].inner_map_fd = -1;
+	}
+
+	return &obj->maps[obj->nr_maps++];
+}
+
+static int
+bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
+			      int sec_idx, Elf_Data *data, void **data_buff)
+{
+	char map_name[BPF_OBJ_NAME_LEN];
+	struct bpf_map_def *def;
+	struct bpf_map *map;
+
+	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;
+	snprintf(map_name, sizeof(map_name), "%.8s%.7s", obj->name,
+		 libbpf_type_to_btf_name[type]);
+	map->name = strdup(map_name);
+	if (!map->name) {
+		pr_warn("failed to alloc map name\n");
+		return -ENOMEM;
+	}
+
+	def = &map->def;
+	def->type = BPF_MAP_TYPE_ARRAY;
+	def->key_size = sizeof(int);
+	def->value_size = data->d_size;
+	def->max_entries = 1;
+	def->map_flags = type == LIBBPF_MAP_RODATA ? BPF_F_RDONLY_PROG : 0;
+	if (obj->caps.array_mmap)
+		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);
+
+	if (data_buff) {
+		*data_buff = malloc(data->d_size);
+		if (!*data_buff) {
+			zfree(&map->name);
+			pr_warn("failed to alloc map content buffer\n");
+			return -ENOMEM;
+		}
+		memcpy(*data_buff, data->d_buf, data->d_size);
+	}
+
+	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)
+{
+	int err;
+
+	if (!obj->caps.global_data)
+		return 0;
+	/*
+	 * Populate obj->maps with libbpf internal maps.
+	 */
+	if (obj->efile.data_shndx >= 0) {
+		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
+						    obj->efile.data_shndx,
+						    obj->efile.data,
+						    &obj->sections.data);
+		if (err)
+			return err;
+	}
+	if (obj->efile.rodata_shndx >= 0) {
+		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
+						    obj->efile.rodata_shndx,
+						    obj->efile.rodata,
+						    &obj->sections.rodata);
+		if (err)
+			return err;
+	}
+	if (obj->efile.bss_shndx >= 0) {
+		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
+						    obj->efile.bss_shndx,
+						    obj->efile.bss, NULL);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	int i, map_def_sz = 0, nr_maps = 0, nr_syms;
+	Elf_Data *data = NULL;
+	Elf_Scn *scn;
+
+	if (obj->efile.maps_shndx < 0)
+		return 0;
+
+	if (!symbols)
+		return -EINVAL;
+
+	scn = elf_getscn(obj->efile.elf, obj->efile.maps_shndx);
+	if (scn)
+		data = elf_getdata(scn, NULL);
+	if (!scn || !data) {
+		pr_warn("failed to get Elf_Data from map section %d\n",
+			obj->efile.maps_shndx);
+		return -EINVAL;
+	}
+
+	/*
+	 * Count number of maps. Each map has a name.
+	 * Array of maps is not supported: only the first element is
+	 * considered.
+	 *
+	 * TODO: Detect array of map and report error.
+	 */
+	nr_syms = symbols->d_size / sizeof(GElf_Sym);
+	for (i = 0; i < nr_syms; i++) {
+		GElf_Sym sym;
+
+		if (!gelf_getsym(symbols, i, &sym))
+			continue;
+		if (sym.st_shndx != obj->efile.maps_shndx)
+			continue;
+		nr_maps++;
+	}
+	/* Assume equally sized map definitions */
+	pr_debug("maps in %s: %d maps in %zd bytes\n",
+		 obj->path, nr_maps, data->d_size);
+
+	if (!data->d_size || nr_maps == 0 || (data->d_size % nr_maps) != 0) {
+		pr_warn("unable to determine map definition size section %s, %d maps in %zd bytes\n",
+			obj->path, nr_maps, data->d_size);
+		return -EINVAL;
+	}
+	map_def_sz = data->d_size / nr_maps;
+
+	/* Fill obj->maps using data in "maps" section.  */
+	for (i = 0; i < nr_syms; i++) {
+		GElf_Sym sym;
+		const char *map_name;
+		struct bpf_map_def *def;
+		struct bpf_map *map;
+
+		if (!gelf_getsym(symbols, i, &sym))
+			continue;
+		if (sym.st_shndx != obj->efile.maps_shndx)
+			continue;
+
+		map = bpf_object__add_map(obj);
+		if (IS_ERR(map))
+			return PTR_ERR(map);
+
+		map_name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
+				      sym.st_name);
+		if (!map_name) {
+			pr_warn("failed to get map #%d name sym string for obj %s\n",
+				i, obj->path);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		map->libbpf_type = LIBBPF_MAP_UNSPEC;
+		map->sec_idx = sym.st_shndx;
+		map->sec_offset = sym.st_value;
+		pr_debug("map '%s' (legacy): at sec_idx %d, offset %zu.\n",
+			 map_name, map->sec_idx, map->sec_offset);
+		if (sym.st_value + map_def_sz > data->d_size) {
+			pr_warn("corrupted maps section in %s: last map \"%s\" too small\n",
+				obj->path, map_name);
+			return -EINVAL;
+		}
+
+		map->name = strdup(map_name);
+		if (!map->name) {
+			pr_warn("failed to alloc map name\n");
+			return -ENOMEM;
+		}
+		pr_debug("map %d is \"%s\"\n", i, map->name);
+		def = (struct bpf_map_def *)(data->d_buf + sym.st_value);
+		/*
+		 * If the definition of the map in the object file fits in
+		 * bpf_map_def, copy it.  Any extra fields in our version
+		 * of bpf_map_def will default to zero as a result of the
+		 * calloc above.
+		 */
+		if (map_def_sz <= sizeof(struct bpf_map_def)) {
+			memcpy(&map->def, def, map_def_sz);
+		} else {
+			/*
+			 * Here the map structure being read is bigger than what
+			 * we expect, truncate if the excess bits are all zero.
+			 * If they are not zero, reject this map as
+			 * incompatible.
+			 */
+			char *b;
+
+			for (b = ((char *)def) + sizeof(struct bpf_map_def);
+			     b < ((char *)def) + map_def_sz; b++) {
+				if (*b != 0) {
+					pr_warn("maps section in %s: \"%s\" has unrecognized, non-zero options\n",
+						obj->path, map_name);
+					if (strict)
+						return -EINVAL;
+				}
+			}
+			memcpy(&map->def, def, sizeof(struct bpf_map_def));
+		}
+	}
+	return 0;
+}
+
+static 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;
+}
+
+/*
+ * 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_type *def,
+			      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 %u.\n",
+			map_name, name, btf_kind(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 %u.\n",
+			map_name, name, btf_kind(arr_t));
+		return false;
+	}
+	arr_info = btf_array(arr_t);
+	*res = arr_info->nelems;
+	return true;
+}
+
+static int build_map_pin_path(struct bpf_map *map, const char *path)
+{
+	char buf[PATH_MAX];
+	int err, len;
+
+	if (!path)
+		path = "/sys/fs/bpf";
+
+	len = snprintf(buf, PATH_MAX, "%s/%s", path, bpf_map__name(map));
+	if (len < 0)
+		return -EINVAL;
+	else if (len >= PATH_MAX)
+		return -ENAMETOOLONG;
+
+	err = bpf_map__set_pin_path(map, buf);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+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)
+{
+	const struct btf_type *var, *def, *t;
+	const struct btf_var_secinfo *vi;
+	const struct btf_var *var_extra;
+	const struct btf_member *m;
+	const char *map_name;
+	struct bpf_map *map;
+	int vlen, i;
+
+	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);
+	vlen = btf_vlen(var);
+
+	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 %u.\n",
+			map_name, btf_kind(var));
+		return -EINVAL;
+	}
+	if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED &&
+	    var_extra->linkage != BTF_VAR_STATIC) {
+		pr_warn("map '%s': unsupported var linkage %u.\n",
+			map_name, 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 %u.\n",
+			map_name, btf_kind(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;
+	pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
+		 map_name, map->sec_idx, map->sec_offset);
+
+	vlen = btf_vlen(def);
+	m = btf_members(def);
+	for (i = 0; i < vlen; i++, m++) {
+		const char *name = btf__name_by_offset(obj->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, obj->btf, def, m,
+					       &map->def.type))
+				return -EINVAL;
+			pr_debug("map '%s': found type = %u.\n",
+				 map_name, map->def.type);
+		} else if (strcmp(name, "max_entries") == 0) {
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &map->def.max_entries))
+				return -EINVAL;
+			pr_debug("map '%s': found max_entries = %u.\n",
+				 map_name, map->def.max_entries);
+		} else if (strcmp(name, "map_flags") == 0) {
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &map->def.map_flags))
+				return -EINVAL;
+			pr_debug("map '%s': found map_flags = %u.\n",
+				 map_name, map->def.map_flags);
+		} else if (strcmp(name, "key_size") == 0) {
+			__u32 sz;
+
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &sz))
+				return -EINVAL;
+			pr_debug("map '%s': found key_size = %u.\n",
+				 map_name, sz);
+			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;
+		} else if (strcmp(name, "key") == 0) {
+			__s64 sz;
+
+			t = btf__type_by_id(obj->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: %u.\n",
+					map_name, btf_kind(t));
+				return -EINVAL;
+			}
+			sz = btf__resolve_size(obj->btf, t->type);
+			if (sz < 0) {
+				pr_warn("map '%s': can't determine key size for type [%u]: %lld.\n",
+					map_name, t->type, sz);
+				return sz;
+			}
+			pr_debug("map '%s': found key [%u], sz = %lld.\n",
+				 map_name, t->type, sz);
+			if (map->def.key_size && map->def.key_size != sz) {
+				pr_warn("map '%s': conflicting key size %u != %lld.\n",
+					map_name, map->def.key_size, sz);
+				return -EINVAL;
+			}
+			map->def.key_size = sz;
+			map->btf_key_type_id = t->type;
+		} else if (strcmp(name, "value_size") == 0) {
+			__u32 sz;
+
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &sz))
+				return -EINVAL;
+			pr_debug("map '%s': found value_size = %u.\n",
+				 map_name, sz);
+			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;
+		} else if (strcmp(name, "value") == 0) {
+			__s64 sz;
+
+			t = btf__type_by_id(obj->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: %u.\n",
+					map_name, btf_kind(t));
+				return -EINVAL;
+			}
+			sz = btf__resolve_size(obj->btf, t->type);
+			if (sz < 0) {
+				pr_warn("map '%s': can't determine value size for type [%u]: %lld.\n",
+					map_name, t->type, sz);
+				return sz;
+			}
+			pr_debug("map '%s': found value [%u], sz = %lld.\n",
+				 map_name, t->type, sz);
+			if (map->def.value_size && map->def.value_size != sz) {
+				pr_warn("map '%s': conflicting value size %u != %lld.\n",
+					map_name, map->def.value_size, sz);
+				return -EINVAL;
+			}
+			map->def.value_size = sz;
+			map->btf_value_type_id = t->type;
+		} else if (strcmp(name, "pinning") == 0) {
+			__u32 val;
+			int err;
+
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &val))
+				return -EINVAL;
+			pr_debug("map '%s': found pinning = %u.\n",
+				 map_name, val);
+
+			if (val != LIBBPF_PIN_NONE &&
+			    val != LIBBPF_PIN_BY_NAME) {
+				pr_warn("map '%s': invalid pinning value %u.\n",
+					map_name, val);
+				return -EINVAL;
+			}
+			if (val == 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;
+				}
+			}
+		} 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.type == BPF_MAP_TYPE_UNSPEC) {
+		pr_warn("map '%s': map type isn't specified.\n", map_name);
+		return -EINVAL;
+	}
+
+	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_getscn(obj->efile.elf, obj->efile.btf_maps_shndx);
+	if (scn)
+		data = elf_getdata(scn, NULL);
+	if (!scn || !data) {
+		pr_warn("failed to get Elf_Data from map section %d (%s)\n",
+			obj->efile.maps_shndx, MAPS_ELF_SEC);
+		return -EINVAL;
+	}
+
+	nr_types = btf__get_nr_types(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;
+			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, bool relaxed_maps,
+				 const char *pin_root_path)
+{
+	bool strict = !relaxed_maps;
+	int err;
+
+	err = bpf_object__init_user_maps(obj, strict);
+	if (err)
+		return err;
+
+	err = bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
+	if (err)
+		return err;
+
+	err = bpf_object__init_global_data_maps(obj);
+	if (err)
+		return err;
+
+	if (obj->nr_maps) {
+		qsort(obj->maps, obj->nr_maps, sizeof(obj->maps[0]),
+		      compare_bpf_map);
+	}
+	return 0;
+}
+
+static bool section_have_execinstr(struct bpf_object *obj, int idx)
+{
+	Elf_Scn *scn;
+	GElf_Shdr sh;
+
+	scn = elf_getscn(obj->efile.elf, idx);
+	if (!scn)
+		return false;
+
+	if (gelf_getshdr(scn, &sh) != &sh)
+		return false;
+
+	if (sh.sh_flags & SHF_EXECINSTR)
+		return true;
+
+	return false;
+}
+
+static void bpf_object__sanitize_btf(struct bpf_object *obj)
+{
+	bool has_datasec = obj->caps.btf_datasec;
+	bool has_func = obj->caps.btf_func;
+	struct btf *btf = obj->btf;
+	struct btf_type *t;
+	int i, j, vlen;
+
+	if (!obj->btf || (has_func && has_datasec))
+		return;
+
+	for (i = 1; i <= btf__get_nr_types(btf); i++) {
+		t = (struct btf_type *)btf__type_by_id(btf, i);
+
+		if (!has_datasec && btf_is_var(t)) {
+			/* replace VAR 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);
+		}
+	}
+}
+
+static void bpf_object__sanitize_btf_ext(struct bpf_object *obj)
+{
+	if (!obj->btf_ext)
+		return;
+
+	if (!obj->caps.btf_func) {
+		btf_ext__free(obj->btf_ext);
+		obj->btf_ext = NULL;
+	}
+}
+
+static bool bpf_object__is_btf_mandatory(const struct bpf_object *obj)
+{
+	return obj->efile.btf_maps_shndx >= 0;
+}
+
+static int bpf_object__init_btf(struct bpf_object *obj,
+				Elf_Data *btf_data,
+				Elf_Data *btf_ext_data)
+{
+	bool btf_required = bpf_object__is_btf_mandatory(obj);
+	int err = 0;
+
+	if (btf_data) {
+		obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
+		if (IS_ERR(obj->btf)) {
+			pr_warn("Error loading ELF section %s: %d.\n",
+				BTF_ELF_SEC, err);
+			goto out;
+		}
+		err = btf__finalize_data(obj, obj->btf);
+		if (err) {
+			pr_warn("Error finalizing %s: %d.\n", BTF_ELF_SEC, err);
+			goto out;
+		}
+	}
+	if (btf_ext_data) {
+		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);
+		if (IS_ERR(obj->btf_ext)) {
+			pr_warn("Error loading ELF section %s: %ld. Ignored and continue.\n",
+				BTF_EXT_ELF_SEC, PTR_ERR(obj->btf_ext));
+			obj->btf_ext = NULL;
+			goto out;
+		}
+	}
+out:
+	if (err || IS_ERR(obj->btf)) {
+		if (btf_required)
+			err = err ? : PTR_ERR(obj->btf);
+		else
+			err = 0;
+		if (!IS_ERR_OR_NULL(obj->btf))
+			btf__free(obj->btf);
+		obj->btf = NULL;
+	}
+	if (btf_required && !obj->btf) {
+		pr_warn("BTF is required, but is missing or corrupted.\n");
+		return err == 0 ? -ENOENT : err;
+	}
+	return 0;
+}
+
+static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
+{
+	int err = 0;
+
+	if (!obj->btf)
+		return 0;
+
+	bpf_object__sanitize_btf(obj);
+	bpf_object__sanitize_btf_ext(obj);
+
+	err = btf__load(obj->btf);
+	if (err) {
+		pr_warn("Error loading %s into kernel: %d.\n",
+			BTF_ELF_SEC, err);
+		btf__free(obj->btf);
+		obj->btf = NULL;
+		/* btf_ext can't exist without btf, so free it as well */
+		if (obj->btf_ext) {
+			btf_ext__free(obj->btf_ext);
+			obj->btf_ext = NULL;
+		}
+
+		if (bpf_object__is_btf_mandatory(obj))
+			return err;
+	}
+	return 0;
+}
+
+static int bpf_object__elf_collect(struct bpf_object *obj, bool relaxed_maps,
+				   const char *pin_root_path)
+{
+	Elf *elf = obj->efile.elf;
+	GElf_Ehdr *ep = &obj->efile.ehdr;
+	Elf_Data *btf_ext_data = NULL;
+	Elf_Data *btf_data = NULL;
+	Elf_Scn *scn = NULL;
+	int idx = 0, err = 0;
+
+	/* Elf is corrupted/truncated, avoid calling elf_strptr. */
+	if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) {
+		pr_warn("failed to get e_shstrndx from %s\n", obj->path);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		char *name;
+		GElf_Shdr sh;
+		Elf_Data *data;
+
+		idx++;
+		if (gelf_getshdr(scn, &sh) != &sh) {
+			pr_warn("failed to get section(%d) header from %s\n",
+				idx, obj->path);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
+		if (!name) {
+			pr_warn("failed to get section(%d) name from %s\n",
+				idx, obj->path);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		data = elf_getdata(scn, 0);
+		if (!data) {
+			pr_warn("failed to get section(%d) data from %s(%s)\n",
+				idx, name, obj->path);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+		pr_debug("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) {
+			obj->efile.maps_shndx = idx;
+		} else if (strcmp(name, MAPS_ELF_SEC) == 0) {
+			obj->efile.btf_maps_shndx = idx;
+		} else if (strcmp(name, BTF_ELF_SEC) == 0) {
+			btf_data = data;
+		} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
+			btf_ext_data = data;
+		} else if (sh.sh_type == SHT_SYMTAB) {
+			if (obj->efile.symbols) {
+				pr_warn("bpf: multiple SYMTAB in %s\n",
+					obj->path);
+				return -LIBBPF_ERRNO__FORMAT;
+			}
+			obj->efile.symbols = data;
+			obj->efile.strtabidx = sh.sh_link;
+		} 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_program(obj, data->d_buf,
+							      data->d_size,
+							      name, idx);
+				if (err) {
+					char errmsg[STRERR_BUFSIZE];
+					char *cp;
+
+					cp = libbpf_strerror_r(-err, errmsg,
+							       sizeof(errmsg));
+					pr_warn("failed to alloc program %s (%s): %s",
+						name, obj->path, cp);
+					return err;
+				}
+			} else if (strcmp(name, ".data") == 0) {
+				obj->efile.data = data;
+				obj->efile.data_shndx = idx;
+			} else if (strcmp(name, ".rodata") == 0) {
+				obj->efile.rodata = data;
+				obj->efile.rodata_shndx = idx;
+			} else {
+				pr_debug("skip section(%d) %s\n", idx, name);
+			}
+		} else if (sh.sh_type == SHT_REL) {
+			int nr_sects = obj->efile.nr_reloc_sects;
+			void *sects = obj->efile.reloc_sects;
+			int sec = sh.sh_info; /* points to other section */
+
+			/* Only do relo for section with exec instructions */
+			if (!section_have_execinstr(obj, sec)) {
+				pr_debug("skip relo %s(%d) for section(%d)\n",
+					 name, idx, sec);
+				continue;
+			}
+
+			sects = reallocarray(sects, nr_sects + 1,
+					     sizeof(*obj->efile.reloc_sects));
+			if (!sects) {
+				pr_warn("reloc_sects realloc failed\n");
+				return -ENOMEM;
+			}
+
+			obj->efile.reloc_sects = sects;
+			obj->efile.nr_reloc_sects++;
+
+			obj->efile.reloc_sects[nr_sects].shdr = sh;
+			obj->efile.reloc_sects[nr_sects].data = data;
+		} else if (sh.sh_type == SHT_NOBITS && strcmp(name, ".bss") == 0) {
+			obj->efile.bss = data;
+			obj->efile.bss_shndx = idx;
+		} else {
+			pr_debug("skip section(%d) %s\n", idx, name);
+		}
+	}
+
+	if (!obj->efile.strtabidx || obj->efile.strtabidx > idx) {
+		pr_warn("Corrupted ELF file: index of strtab invalid\n");
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	err = bpf_object__init_btf(obj, btf_data, btf_ext_data);
+	if (!err)
+		err = bpf_object__init_maps(obj, relaxed_maps, pin_root_path);
+	if (!err)
+		err = bpf_object__sanitize_and_load_btf(obj);
+	if (!err)
+		err = bpf_object__init_prog_names(obj);
+	return err;
+}
+
+static struct bpf_program *
+bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
+{
+	struct bpf_program *prog;
+	size_t i;
+
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		if (prog->idx == idx)
+			return prog;
+	}
+	return NULL;
+}
+
+struct bpf_program *
+bpf_object__find_program_by_title(const struct bpf_object *obj,
+				  const char *title)
+{
+	struct bpf_program *pos;
+
+	bpf_object__for_each_program(pos, obj) {
+		if (pos->section_name && !strcmp(pos->section_name, title))
+			return pos;
+	}
+	return NULL;
+}
+
+static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
+				      int shndx)
+{
+	return shndx == obj->efile.data_shndx ||
+	       shndx == obj->efile.bss_shndx ||
+	       shndx == obj->efile.rodata_shndx;
+}
+
+static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
+				      int shndx)
+{
+	return shndx == obj->efile.maps_shndx ||
+	       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.data_shndx)
+		return LIBBPF_MAP_DATA;
+	else if (shndx == obj->efile.bss_shndx)
+		return LIBBPF_MAP_BSS;
+	else if (shndx == obj->efile.rodata_shndx)
+		return LIBBPF_MAP_RODATA;
+	else
+		return LIBBPF_MAP_UNSPEC;
+}
+
+static int bpf_program__record_reloc(struct bpf_program *prog,
+				     struct reloc_desc *reloc_desc,
+				     __u32 insn_idx, const char *name,
+				     const GElf_Sym *sym, const GElf_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;
+	struct bpf_map *map;
+
+	/* sub-program call relocation */
+	if (insn->code == (BPF_JMP | BPF_CALL)) {
+		if (insn->src_reg != BPF_PSEUDO_CALL) {
+			pr_warn("incorrect bpf_call opcode\n");
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		/* text_shndx can be 0, if no default "main" program exists */
+		if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
+			pr_warn("bad call relo against section %u\n", shdr_idx);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		if (sym->st_value % 8) {
+			pr_warn("bad call relo offset: %llu\n", (__u64)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;
+		obj->has_pseudo_calls = true;
+		return 0;
+	}
+
+	if (insn->code != (BPF_LD | BPF_IMM | BPF_DW)) {
+		pr_warn("invalid relo for insns[%d].code 0x%x\n",
+			insn_idx, insn->code);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+	if (!shdr_idx || shdr_idx >= SHN_LORESERVE) {
+		pr_warn("invalid relo for \'%s\' in special section 0x%x; forgot to initialize global var?..\n",
+			name, shdr_idx);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+
+	type = bpf_object__section_to_libbpf_map_type(obj, shdr_idx);
+
+	/* generic map reference relocation */
+	if (type == LIBBPF_MAP_UNSPEC) {
+		if (!bpf_object__shndx_is_maps(obj, shdr_idx)) {
+			pr_warn("bad map relo against section %u\n",
+				shdr_idx);
+			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("found map %zd (%s, sec %d, off %zu) for insn %u\n",
+				 map_idx, map->name, map->sec_idx,
+				 map->sec_offset, insn_idx);
+			break;
+		}
+		if (map_idx >= nr_maps) {
+			pr_warn("map relo failed to find map for sec %u, off %llu\n",
+				shdr_idx, (__u64)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("bad data relo against section %u\n", shdr_idx);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+	if (!obj->caps.global_data) {
+		pr_warn("relocation: kernel does not support global \'%s\' variable access in insns[%d]\n",
+			name, insn_idx);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+	for (map_idx = 0; map_idx < nr_maps; map_idx++) {
+		map = &obj->maps[map_idx];
+		if (map->libbpf_type != type)
+			continue;
+		pr_debug("found data map %zd (%s, sec %d, off %zu) for insn %u\n",
+			 map_idx, map->name, map->sec_idx, map->sec_offset,
+			 insn_idx);
+		break;
+	}
+	if (map_idx >= nr_maps) {
+		pr_warn("data relo failed to find map for sec %u\n",
+			shdr_idx);
+		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 int
+bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
+			   Elf_Data *data, struct bpf_object *obj)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	int err, i, nrels;
+
+	pr_debug("collecting relocating info for: '%s'\n", prog->section_name);
+	nrels = shdr->sh_size / shdr->sh_entsize;
+
+	prog->reloc_desc = malloc(sizeof(*prog->reloc_desc) * nrels);
+	if (!prog->reloc_desc) {
+		pr_warn("failed to alloc memory in relocation\n");
+		return -ENOMEM;
+	}
+	prog->nr_reloc = nrels;
+
+	for (i = 0; i < nrels; i++) {
+		const char *name;
+		__u32 insn_idx;
+		GElf_Sym sym;
+		GElf_Rel rel;
+
+		if (!gelf_getrel(data, i, &rel)) {
+			pr_warn("relocation: failed to get %d reloc\n", i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+		if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) {
+			pr_warn("relocation: symbol %"PRIx64" not found\n",
+				GELF_R_SYM(rel.r_info));
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+		if (rel.r_offset % sizeof(struct bpf_insn))
+			return -LIBBPF_ERRNO__FORMAT;
+
+		insn_idx = rel.r_offset / sizeof(struct bpf_insn);
+		name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
+				  sym.st_name) ? : "<?>";
+
+		pr_debug("relo for shdr %u, symb %llu, value %llu, type %d, bind %d, name %d (\'%s\'), insn %u\n",
+			 (__u32)sym.st_shndx, (__u64)GELF_R_SYM(rel.r_info),
+			 (__u64)sym.st_value, GELF_ST_TYPE(sym.st_info),
+			 GELF_ST_BIND(sym.st_info), sym.st_name, name,
+			 insn_idx);
+
+		err = bpf_program__record_reloc(prog, &prog->reloc_desc[i],
+						insn_idx, name, &sym, &rel);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map)
+{
+	struct bpf_map_def *def = &map->def;
+	__u32 key_type_id = 0, value_type_id = 0;
+	int ret;
+
+	/* if it's BTF-defined map, we don't need to search for type IDs */
+	if (map->sec_idx == obj->efile.btf_maps_shndx)
+		return 0;
+
+	if (!bpf_map__is_internal(map)) {
+		ret = btf__get_map_kv_tids(obj->btf, map->name, def->key_size,
+					   def->value_size, &key_type_id,
+					   &value_type_id);
+	} else {
+		/*
+		 * LLVM annotates global data differently in BTF, that is,
+		 * only as '.data', '.bss' or '.rodata'.
+		 */
+		ret = btf__find_by_name(obj->btf,
+				libbpf_type_to_btf_name[map->libbpf_type]);
+	}
+	if (ret < 0)
+		return ret;
+
+	map->btf_key_type_id = key_type_id;
+	map->btf_value_type_id = bpf_map__is_internal(map) ?
+				 ret : value_type_id;
+	return 0;
+}
+
+int bpf_map__reuse_fd(struct bpf_map *map, int fd)
+{
+	struct bpf_map_info info = {};
+	__u32 len = sizeof(info);
+	int new_fd, err;
+	char *new_name;
+
+	err = bpf_obj_get_info_by_fd(fd, &info, &len);
+	if (err)
+		return err;
+
+	new_name = strdup(info.name);
+	if (!new_name)
+		return -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;
+
+	return 0;
+
+err_close_new_fd:
+	close(new_fd);
+err_free_new_name:
+	free(new_name);
+	return err;
+}
+
+int bpf_map__resize(struct bpf_map *map, __u32 max_entries)
+{
+	if (!map || !max_entries)
+		return -EINVAL;
+
+	/* If map already created, its attributes can't be changed. */
+	if (map->fd >= 0)
+		return -EBUSY;
+
+	map->def.max_entries = max_entries;
+
+	return 0;
+}
+
+static int
+bpf_object__probe_name(struct bpf_object *obj)
+{
+	struct bpf_load_program_attr attr;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int ret;
+
+	/* make sure basic loading works */
+
+	memset(&attr, 0, sizeof(attr));
+	attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	attr.insns = insns;
+	attr.insns_cnt = ARRAY_SIZE(insns);
+	attr.license = "GPL";
+
+	ret = bpf_load_program_xattr(&attr, NULL, 0);
+	if (ret < 0) {
+		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+		pr_warn("Error in %s():%s(%d). Couldn't load basic 'r0 = 0' BPF program.\n",
+			__func__, cp, errno);
+		return -errno;
+	}
+	close(ret);
+
+	/* now try the same program, but with the name */
+
+	attr.name = "test";
+	ret = bpf_load_program_xattr(&attr, NULL, 0);
+	if (ret >= 0) {
+		obj->caps.name = 1;
+		close(ret);
+	}
+
+	return 0;
+}
+
+static int
+bpf_object__probe_global_data(struct bpf_object *obj)
+{
+	struct bpf_load_program_attr prg_attr;
+	struct bpf_create_map_attr map_attr;
+	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;
+
+	memset(&map_attr, 0, sizeof(map_attr));
+	map_attr.map_type = BPF_MAP_TYPE_ARRAY;
+	map_attr.key_size = sizeof(int);
+	map_attr.value_size = 32;
+	map_attr.max_entries = 1;
+
+	map = bpf_create_map_xattr(&map_attr);
+	if (map < 0) {
+		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+		pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
+			__func__, cp, errno);
+		return -errno;
+	}
+
+	insns[0].imm = map;
+
+	memset(&prg_attr, 0, sizeof(prg_attr));
+	prg_attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	prg_attr.insns = insns;
+	prg_attr.insns_cnt = ARRAY_SIZE(insns);
+	prg_attr.license = "GPL";
+
+	ret = bpf_load_program_xattr(&prg_attr, NULL, 0);
+	if (ret >= 0) {
+		obj->caps.global_data = 1;
+		close(ret);
+	}
+
+	close(map);
+	return 0;
+}
+
+static int bpf_object__probe_btf_func(struct bpf_object *obj)
+{
+	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),
+	};
+	int btf_fd;
+
+	btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
+				      strs, sizeof(strs));
+	if (btf_fd >= 0) {
+		obj->caps.btf_func = 1;
+		close(btf_fd);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int bpf_object__probe_btf_datasec(struct bpf_object *obj)
+{
+	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),
+	};
+	int btf_fd;
+
+	btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
+				      strs, sizeof(strs));
+	if (btf_fd >= 0) {
+		obj->caps.btf_datasec = 1;
+		close(btf_fd);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int bpf_object__probe_array_mmap(struct bpf_object *obj)
+{
+	struct bpf_create_map_attr attr = {
+		.map_type = BPF_MAP_TYPE_ARRAY,
+		.map_flags = BPF_F_MMAPABLE,
+		.key_size = sizeof(int),
+		.value_size = sizeof(int),
+		.max_entries = 1,
+	};
+	int fd;
+
+	fd = bpf_create_map_xattr(&attr);
+	if (fd >= 0) {
+		obj->caps.array_mmap = 1;
+		close(fd);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int
+bpf_object__probe_caps(struct bpf_object *obj)
+{
+	int (*probe_fn[])(struct bpf_object *obj) = {
+		bpf_object__probe_name,
+		bpf_object__probe_global_data,
+		bpf_object__probe_btf_func,
+		bpf_object__probe_btf_datasec,
+		bpf_object__probe_array_mmap,
+	};
+	int i, ret;
+
+	for (i = 0; i < ARRAY_SIZE(probe_fn); i++) {
+		ret = probe_fn[i](obj);
+		if (ret < 0)
+			pr_debug("Probe #%d failed with %d.\n", i, ret);
+	}
+
+	return 0;
+}
+
+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;
+
+	map_info_len = sizeof(map_info);
+
+	if (bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len)) {
+		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);
+}
+
+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);
+	if (err) {
+		close(pin_fd);
+		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)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err, zero = 0;
+	__u8 *data;
+
+	/* Nothing to do here since kernel already zero-initializes .bss map. */
+	if (map->libbpf_type == LIBBPF_MAP_BSS)
+		return 0;
+
+	data = map->libbpf_type == LIBBPF_MAP_DATA ?
+	       obj->sections.data : obj->sections.rodata;
+
+	err = bpf_map_update_elem(map->fd, &zero, data, 0);
+	/* Freeze .rodata map as read-only from syscall side. */
+	if (!err && map->libbpf_type == LIBBPF_MAP_RODATA) {
+		err = bpf_map_freeze(map->fd);
+		if (err) {
+			cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+			pr_warn("Error freezing map(%s) as read-only: %s\n",
+				map->name, cp);
+			err = 0;
+		}
+	}
+	return err;
+}
+
+static int
+bpf_object__create_maps(struct bpf_object *obj)
+{
+	struct bpf_create_map_attr create_attr = {};
+	int nr_cpus = 0;
+	unsigned int i;
+	int err;
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		struct bpf_map *map = &obj->maps[i];
+		struct bpf_map_def *def = &map->def;
+		char *cp, errmsg[STRERR_BUFSIZE];
+		int *pfd = &map->fd;
+
+		if (map->pin_path) {
+			err = bpf_object__reuse_map(map);
+			if (err) {
+				pr_warn("error reusing pinned map %s\n",
+					map->name);
+				return err;
+			}
+		}
+
+		if (map->fd >= 0) {
+			pr_debug("skip map create (preset) %s: fd=%d\n",
+				 map->name, map->fd);
+			continue;
+		}
+
+		if (obj->caps.name)
+			create_attr.name = map->name;
+		create_attr.map_ifindex = map->map_ifindex;
+		create_attr.map_type = def->type;
+		create_attr.map_flags = def->map_flags;
+		create_attr.key_size = def->key_size;
+		create_attr.value_size = def->value_size;
+		if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY &&
+		    !def->max_entries) {
+			if (!nr_cpus)
+				nr_cpus = libbpf_num_possible_cpus();
+			if (nr_cpus < 0) {
+				pr_warn("failed to determine number of system CPUs: %d\n",
+					nr_cpus);
+				err = nr_cpus;
+				goto err_out;
+			}
+			pr_debug("map '%s': setting size to %d\n",
+				 map->name, nr_cpus);
+			create_attr.max_entries = nr_cpus;
+		} else {
+			create_attr.max_entries = def->max_entries;
+		}
+		create_attr.btf_fd = 0;
+		create_attr.btf_key_type_id = 0;
+		create_attr.btf_value_type_id = 0;
+		if (bpf_map_type__is_map_in_map(def->type) &&
+		    map->inner_map_fd >= 0)
+			create_attr.inner_map_fd = map->inner_map_fd;
+
+		if (obj->btf && !bpf_map_find_btf_info(obj, map)) {
+			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;
+		}
+
+		*pfd = bpf_create_map_xattr(&create_attr);
+		if (*pfd < 0 && (create_attr.btf_key_type_id ||
+				 create_attr.btf_value_type_id)) {
+			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;
+			*pfd = bpf_create_map_xattr(&create_attr);
+		}
+
+		if (*pfd < 0) {
+			size_t j;
+
+			err = -errno;
+err_out:
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+			pr_warn("failed to create map (name: '%s'): %s(%d)\n",
+				map->name, cp, err);
+			for (j = 0; j < i; j++)
+				zclose(obj->maps[j].fd);
+			return err;
+		}
+
+		if (bpf_map__is_internal(map)) {
+			err = bpf_object__populate_internal_map(obj, map);
+			if (err < 0) {
+				zclose(*pfd);
+				goto err_out;
+			}
+		}
+
+		if (map->pin_path && !map->pinned) {
+			err = bpf_map__pin(map, NULL);
+			if (err) {
+				pr_warn("failed to auto-pin map name '%s' at '%s'\n",
+					map->name, map->pin_path);
+				return err;
+			}
+		}
+
+		pr_debug("created map %s: fd=%d\n", map->name, *pfd);
+	}
+
+	return 0;
+}
+
+static int
+check_btf_ext_reloc_err(struct bpf_program *prog, int err,
+			void *btf_prog_info, const char *info_name)
+{
+	if (err != -ENOENT) {
+		pr_warn("Error in loading %s for sec %s.\n",
+			info_name, prog->section_name);
+		return err;
+	}
+
+	/* err == -ENOENT (i.e. prog->section_name not found in btf_ext) */
+
+	if (btf_prog_info) {
+		/*
+		 * Some info has already been found but has problem
+		 * in the last btf_ext reloc. Must have to error out.
+		 */
+		pr_warn("Error in relocating %s for sec %s.\n",
+			info_name, prog->section_name);
+		return err;
+	}
+
+	/* Have problem loading the very first info. Ignore the rest. */
+	pr_warn("Cannot find %s for main program sec %s. Ignore all %s.\n",
+		info_name, prog->section_name, info_name);
+	return 0;
+}
+
+static int
+bpf_program_reloc_btf_ext(struct bpf_program *prog, struct bpf_object *obj,
+			  const char *section_name,  __u32 insn_offset)
+{
+	int err;
+
+	if (!insn_offset || prog->func_info) {
+		/*
+		 * !insn_offset => main program
+		 *
+		 * For sub prog, the main program's func_info has to
+		 * be loaded first (i.e. prog->func_info != NULL)
+		 */
+		err = btf_ext__reloc_func_info(obj->btf, obj->btf_ext,
+					       section_name, insn_offset,
+					       &prog->func_info,
+					       &prog->func_info_cnt);
+		if (err)
+			return check_btf_ext_reloc_err(prog, err,
+						       prog->func_info,
+						       "bpf_func_info");
+
+		prog->func_info_rec_size = btf_ext__func_info_rec_size(obj->btf_ext);
+	}
+
+	if (!insn_offset || prog->line_info) {
+		err = btf_ext__reloc_line_info(obj->btf, obj->btf_ext,
+					       section_name, insn_offset,
+					       &prog->line_info,
+					       &prog->line_info_cnt);
+		if (err)
+			return check_btf_ext_reloc_err(prog, err,
+						       prog->line_info,
+						       "bpf_line_info");
+
+		prog->line_info_rec_size = btf_ext__line_info_rec_size(obj->btf_ext);
+	}
+
+	return 0;
+}
+
+#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];
+	/* 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;
+};
+
+static bool str_is_empty(const char *s)
+{
+	return !s || !s[0];
+}
+
+/*
+ * Turn bpf_field_reloc 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:
+ *   - intial 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).
+ *
+ */
+static int bpf_core_spec_parse(const struct btf *btf,
+			       __u32 type_id,
+			       const char *spec_str,
+			       struct bpf_core_spec *spec)
+{
+	int access_idx, parsed_len, i;
+	const struct btf_type *t;
+	const char *name;
+	__u32 id;
+	__s64 sz;
+
+	if (str_is_empty(spec_str) || *spec_str == ':')
+		return -EINVAL;
+
+	memset(spec, 0, sizeof(*spec));
+	spec->btf = btf;
+
+	/* 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;
+
+	/* first spec value is always reloc type array index */
+	t = skip_mods_and_typedefs(btf, type_id, &id);
+	if (!t)
+		return -EINVAL;
+
+	access_idx = spec->raw_spec[0];
+	spec->spec[0].type_id = id;
+	spec->spec[0].idx = access_idx;
+	spec->len++;
+
+	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];
+
+		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;
+
+				spec->spec[spec->len].type_id = id;
+				spec->spec[spec->len].idx = access_idx;
+				spec->spec[spec->len].name = name;
+				spec->len++;
+			}
+
+			id = m->type;
+		} else if (btf_is_array(t)) {
+			const struct btf_array *a = btf_array(t);
+
+			t = skip_mods_and_typedefs(btf, a->type, &id);
+			if (!t || 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("relo for [%u] %s (at idx %d) captures type [%d] of unexpected kind %d\n",
+				type_id, spec_str, i, id, btf_kind(t));
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+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.
+ */
+static 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;
+}
+
+/* dynamically sized list of type IDs */
+struct ids_vec {
+	__u32 *data;
+	int len;
+};
+
+static void bpf_core_free_cands(struct ids_vec *cand_ids)
+{
+	free(cand_ids->data);
+	free(cand_ids);
+}
+
+static struct ids_vec *bpf_core_find_cands(const struct btf *local_btf,
+					   __u32 local_type_id,
+					   const struct btf *targ_btf)
+{
+	size_t local_essent_len, targ_essent_len;
+	const char *local_name, *targ_name;
+	const struct btf_type *t;
+	struct ids_vec *cand_ids;
+	__u32 *new_ids;
+	int i, err, n;
+
+	t = btf__type_by_id(local_btf, local_type_id);
+	if (!t)
+		return ERR_PTR(-EINVAL);
+
+	local_name = btf__name_by_offset(local_btf, t->name_off);
+	if (str_is_empty(local_name))
+		return ERR_PTR(-EINVAL);
+	local_essent_len = bpf_core_essential_name_len(local_name);
+
+	cand_ids = calloc(1, sizeof(*cand_ids));
+	if (!cand_ids)
+		return ERR_PTR(-ENOMEM);
+
+	n = btf__get_nr_types(targ_btf);
+	for (i = 1; i <= n; i++) {
+		t = btf__type_by_id(targ_btf, i);
+		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) {
+			pr_debug("[%d] %s: found candidate [%d] %s\n",
+				 local_type_id, local_name, i, targ_name);
+			new_ids = realloc(cand_ids->data, cand_ids->len + 1);
+			if (!new_ids) {
+				err = -ENOMEM;
+				goto err_out;
+			}
+			cand_ids->data = new_ids;
+			cand_ids->data[cand_ids->len++] = i;
+		}
+	}
+	return cand_ids;
+err_out:
+	bpf_core_free_cands(cand_ids);
+	return ERR_PTR(err);
+}
+
+/* Check two types for compatibility, skipping const/volatile/restrict and
+ * typedefs, to ensure we are relocating 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;
+ *   - 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(local_type) != btf_kind(targ_type))
+		return 0;
+
+	switch (btf_kind(local_type)) {
+	case BTF_KIND_PTR:
+		return 1;
+	case BTF_KIND_FWD:
+	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:
+		pr_warn("unexpected kind %d relocated, local [%d], target [%d]\n",
+			btf_kind(local_type), local_id, targ_id);
+		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;
+
+	memset(targ_spec, 0, sizeof(*targ_spec));
+	targ_spec->btf = targ_btf;
+
+	local_acc = &local_spec->spec[0];
+	targ_acc = &targ_spec->spec[0];
+
+	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;
+
+				if (!btf_is_array(targ_type))
+					return 0;
+
+				a = btf_array(targ_type);
+				if (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 struct bpf_program *prog,
+				    const struct bpf_field_reloc *relo,
+				    const struct bpf_core_spec *spec,
+				    __u32 *val, bool *validate)
+{
+	const struct bpf_core_accessor *acc = &spec->spec[spec->len - 1];
+	const struct btf_type *t = btf__type_by_id(spec->btf, acc->type_id);
+	__u32 byte_off, byte_sz, bit_off, bit_sz;
+	const struct btf_member *m;
+	const struct btf_type *mt;
+	bool bitfield;
+	__s64 sz;
+
+	/* a[n] accessor needs special handling */
+	if (!acc->name) {
+		if (relo->kind == BPF_FIELD_BYTE_OFFSET) {
+			*val = spec->bit_offset / 8;
+		} else if (relo->kind == BPF_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",
+				bpf_program__title(prog, false),
+				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, NULL);
+	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",
+					bpf_program__title(prog, false),
+					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, m->type);
+		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_FIELD_BYTE_OFFSET:
+		*val = byte_off;
+		break;
+	case BPF_FIELD_BYTE_SIZE:
+		*val = byte_sz;
+		break;
+	case BPF_FIELD_SIGNED:
+		/* enums will be assumed unsigned */
+		*val = btf_is_enum(mt) ||
+		       (btf_int_encoding(mt) & BTF_INT_SIGNED);
+		if (validate)
+			*validate = true; /* signedness is never ambiguous */
+		break;
+	case BPF_FIELD_LSHIFT_U64:
+#if __BYTE_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_FIELD_RSHIFT_U64:
+		*val = 64 - bit_sz;
+		if (validate)
+			*validate = true; /* right shift is never ambiguous */
+		break;
+	case BPF_FIELD_EXISTS:
+	default:
+		pr_warn("prog '%s': unknown relo %d at insn #%d\n",
+			bpf_program__title(prog, false),
+			relo->kind, relo->insn_off / 8);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Patch relocatable BPF instruction.
+ *
+ * Patched value is determined by relocation kind and target specification.
+ * For field existence relocation target spec will be NULL if field 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 three kinds of BPF instructions are supported:
+ * 1. rX = <imm> (assignment with immediate operand);
+ * 2. rX += <imm> (arithmetic operations with immediate operand);
+ */
+static int bpf_core_reloc_insn(struct bpf_program *prog,
+			       const struct bpf_field_reloc *relo,
+			       const struct bpf_core_spec *local_spec,
+			       const struct bpf_core_spec *targ_spec)
+{
+	bool failed = false, validate = true;
+	__u32 orig_val, new_val;
+	struct bpf_insn *insn;
+	int insn_idx, err;
+	__u8 class;
+
+	if (relo->insn_off % sizeof(struct bpf_insn))
+		return -EINVAL;
+	insn_idx = relo->insn_off / sizeof(struct bpf_insn);
+
+	if (relo->kind == BPF_FIELD_EXISTS) {
+		orig_val = 1; /* can't generate EXISTS relo w/o local field */
+		new_val = targ_spec ? 1 : 0;
+	} else if (!targ_spec) {
+		failed = true;
+		new_val = (__u32)-1;
+	} else {
+		err = bpf_core_calc_field_relo(prog, relo, local_spec,
+					       &orig_val, &validate);
+		if (err)
+			return err;
+		err = bpf_core_calc_field_relo(prog, relo, targ_spec,
+					       &new_val, NULL);
+		if (err)
+			return err;
+	}
+
+	insn = &prog->insns[insn_idx];
+	class = BPF_CLASS(insn->code);
+
+	if (class == BPF_ALU || class == BPF_ALU64) {
+		if (BPF_SRC(insn->code) != BPF_K)
+			return -EINVAL;
+		if (!failed && validate && insn->imm != orig_val) {
+			pr_warn("prog '%s': unexpected insn #%d value: got %u, exp %u -> %u\n",
+				bpf_program__title(prog, false), insn_idx,
+				insn->imm, orig_val, new_val);
+			return -EINVAL;
+		}
+		orig_val = insn->imm;
+		insn->imm = new_val;
+		pr_debug("prog '%s': patched insn #%d (ALU/ALU64)%s imm %u -> %u\n",
+			 bpf_program__title(prog, false), insn_idx,
+			 failed ? " w/ failed reloc" : "", orig_val, new_val);
+	} else {
+		pr_warn("prog '%s': trying to relocate unrecognized insn #%d, code:%x, src:%x, dst:%x, off:%x, imm:%x\n",
+			bpf_program__title(prog, false),
+			insn_idx, insn->code, insn->src_reg, insn->dst_reg,
+			insn->off, insn->imm);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static struct btf *btf_load_raw(const char *path)
+{
+	struct btf *btf;
+	size_t read_cnt;
+	struct stat st;
+	void *data;
+	FILE *f;
+
+	if (stat(path, &st))
+		return ERR_PTR(-errno);
+
+	data = malloc(st.st_size);
+	if (!data)
+		return ERR_PTR(-ENOMEM);
+
+	f = fopen(path, "rb");
+	if (!f) {
+		btf = ERR_PTR(-errno);
+		goto cleanup;
+	}
+
+	read_cnt = fread(data, 1, st.st_size, f);
+	fclose(f);
+	if (read_cnt < st.st_size) {
+		btf = ERR_PTR(-EBADF);
+		goto cleanup;
+	}
+
+	btf = btf__new(data, read_cnt);
+
+cleanup:
+	free(data);
+	return btf;
+}
+
+/*
+ * Probe few well-known locations for vmlinux kernel image and try to load BTF
+ * data out of it to use for target BTF.
+ */
+static struct btf *bpf_core_find_kernel_btf(void)
+{
+	struct {
+		const char *path_fmt;
+		bool raw_btf;
+	} locations[] = {
+		/* try canonical vmlinux BTF through sysfs first */
+		{ "/sys/kernel/btf/vmlinux", true /* raw BTF */ },
+		/* fall back to trying to find vmlinux ELF 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;
+
+	uname(&buf);
+
+	for (i = 0; i < ARRAY_SIZE(locations); i++) {
+		snprintf(path, PATH_MAX, locations[i].path_fmt, buf.release);
+
+		if (access(path, R_OK))
+			continue;
+
+		if (locations[i].raw_btf)
+			btf = btf_load_raw(path);
+		else
+			btf = btf__parse_elf(path, NULL);
+
+		pr_debug("loading kernel BTF '%s': %ld\n",
+			 path, IS_ERR(btf) ? PTR_ERR(btf) : 0);
+		if (IS_ERR(btf))
+			continue;
+
+		return btf;
+	}
+
+	pr_warn("failed to find valid kernel BTF\n");
+	return ERR_PTR(-ESRCH);
+}
+
+/* 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
+ */
+static void bpf_core_dump_spec(int level, const struct bpf_core_spec *spec)
+{
+	const struct btf_type *t;
+	const char *s;
+	__u32 type_id;
+	int i;
+
+	type_id = spec->spec[0].type_id;
+	t = btf__type_by_id(spec->btf, type_id);
+	s = btf__name_by_offset(spec->btf, t->name_off);
+	libbpf_print(level, "[%u] %s + ", type_id, s);
+
+	for (i = 0; i < spec->raw_len; i++)
+		libbpf_print(level, "%d%s", spec->raw_spec[i],
+			     i == spec->raw_len - 1 ? " => " : ":");
+
+	libbpf_print(level, "%u.%u @ &x",
+		     spec->bit_offset / 8, spec->bit_offset % 8);
+
+	for (i = 0; i < spec->len; i++) {
+		if (spec->spec[i].name)
+			libbpf_print(level, ".%s", spec->spec[i].name);
+		else
+			libbpf_print(level, "[%u]", spec->spec[i].idx);
+	}
+
+}
+
+static size_t bpf_core_hash_fn(const void *key, void *ctx)
+{
+	return (size_t)key;
+}
+
+static bool bpf_core_equal_fn(const void *k1, const void *k2, void *ctx)
+{
+	return k1 == k2;
+}
+
+static void *u32_as_hash_key(__u32 x)
+{
+	return (void *)(uintptr_t)x;
+}
+
+/*
+ * CO-RE relocate single instruction.
+ *
+ * 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 accomodate
+ *    imprefection 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 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_field_reloc 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.
+ */
+static int bpf_core_reloc_field(struct bpf_program *prog,
+				 const struct bpf_field_reloc *relo,
+				 int relo_idx,
+				 const struct btf *local_btf,
+				 const struct btf *targ_btf,
+				 struct hashmap *cand_cache)
+{
+	const char *prog_name = bpf_program__title(prog, false);
+	struct bpf_core_spec local_spec, cand_spec, targ_spec;
+	const void *type_key = u32_as_hash_key(relo->type_id);
+	const struct btf_type *local_type, *cand_type;
+	const char *local_name, *cand_name;
+	struct ids_vec *cand_ids;
+	__u32 local_id, cand_id;
+	const char *spec_str;
+	int i, j, err;
+
+	local_id = relo->type_id;
+	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 (str_is_empty(local_name))
+		return -EINVAL;
+
+	spec_str = btf__name_by_offset(local_btf, relo->access_str_off);
+	if (str_is_empty(spec_str))
+		return -EINVAL;
+
+	err = bpf_core_spec_parse(local_btf, local_id, spec_str, &local_spec);
+	if (err) {
+		pr_warn("prog '%s': relo #%d: parsing [%d] %s + %s failed: %d\n",
+			prog_name, relo_idx, local_id, local_name, spec_str,
+			err);
+		return -EINVAL;
+	}
+
+	pr_debug("prog '%s': relo #%d: kind %d, spec is ", prog_name, relo_idx,
+		 relo->kind);
+	bpf_core_dump_spec(LIBBPF_DEBUG, &local_spec);
+	libbpf_print(LIBBPF_DEBUG, "\n");
+
+	if (!hashmap__find(cand_cache, type_key, (void **)&cand_ids)) {
+		cand_ids = bpf_core_find_cands(local_btf, local_id, targ_btf);
+		if (IS_ERR(cand_ids)) {
+			pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s: %ld",
+				prog_name, relo_idx, local_id, local_name,
+				PTR_ERR(cand_ids));
+			return PTR_ERR(cand_ids);
+		}
+		err = hashmap__set(cand_cache, type_key, cand_ids, NULL, NULL);
+		if (err) {
+			bpf_core_free_cands(cand_ids);
+			return err;
+		}
+	}
+
+	for (i = 0, j = 0; i < cand_ids->len; i++) {
+		cand_id = cand_ids->data[i];
+		cand_type = btf__type_by_id(targ_btf, cand_id);
+		cand_name = btf__name_by_offset(targ_btf, cand_type->name_off);
+
+		err = bpf_core_spec_match(&local_spec, targ_btf,
+					  cand_id, &cand_spec);
+		pr_debug("prog '%s': relo #%d: matching candidate #%d %s against spec ",
+			 prog_name, relo_idx, i, cand_name);
+		bpf_core_dump_spec(LIBBPF_DEBUG, &cand_spec);
+		libbpf_print(LIBBPF_DEBUG, ": %d\n", err);
+		if (err < 0) {
+			pr_warn("prog '%s': relo #%d: matching error: %d\n",
+				prog_name, relo_idx, err);
+			return err;
+		}
+		if (err == 0)
+			continue;
+
+		if (j == 0) {
+			targ_spec = cand_spec;
+		} else if (cand_spec.bit_offset != targ_spec.bit_offset) {
+			/* if there are many candidates, they should all
+			 * resolve to the same bit offset
+			 */
+			pr_warn("prog '%s': relo #%d: offset ambiguity: %u != %u\n",
+				prog_name, relo_idx, cand_spec.bit_offset,
+				targ_spec.bit_offset);
+			return -EINVAL;
+		}
+
+		cand_ids->data[j++] = cand_spec.spec[0].type_id;
+	}
+
+	/*
+	 * For BPF_FIELD_EXISTS relo or when relaxed CO-RE reloc mode is
+	 * requested, 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)
+		cand_ids->len = j;
+
+	if (j == 0 && !prog->obj->relaxed_core_relocs &&
+	    relo->kind != BPF_FIELD_EXISTS) {
+		pr_warn("prog '%s': relo #%d: no matching targets found for [%d] %s + %s\n",
+			prog_name, relo_idx, local_id, local_name, spec_str);
+		return -ESRCH;
+	}
+
+	/* bpf_core_reloc_insn should know how to handle missing targ_spec */
+	err = bpf_core_reloc_insn(prog, relo, &local_spec,
+				  j ? &targ_spec : NULL);
+	if (err) {
+		pr_warn("prog '%s': relo #%d: failed to patch insn at offset %d: %d\n",
+			prog_name, relo_idx, relo->insn_off, err);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int
+bpf_core_reloc_fields(struct bpf_object *obj, const char *targ_btf_path)
+{
+	const struct btf_ext_info_sec *sec;
+	const struct bpf_field_reloc *rec;
+	const struct btf_ext_info *seg;
+	struct hashmap_entry *entry;
+	struct hashmap *cand_cache = NULL;
+	struct bpf_program *prog;
+	struct btf *targ_btf;
+	const char *sec_name;
+	int i, err = 0;
+
+	if (targ_btf_path)
+		targ_btf = btf__parse_elf(targ_btf_path, NULL);
+	else
+		targ_btf = bpf_core_find_kernel_btf();
+	if (IS_ERR(targ_btf)) {
+		pr_warn("failed to get target BTF: %ld\n", PTR_ERR(targ_btf));
+		return PTR_ERR(targ_btf);
+	}
+
+	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->field_reloc_info;
+	for_each_btf_ext_sec(seg, sec) {
+		sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
+		if (str_is_empty(sec_name)) {
+			err = -EINVAL;
+			goto out;
+		}
+		prog = bpf_object__find_program_by_title(obj, sec_name);
+		if (!prog) {
+			pr_warn("failed to find program '%s' for CO-RE offset relocation\n",
+				sec_name);
+			err = -EINVAL;
+			goto out;
+		}
+
+		pr_debug("prog '%s': performing %d CO-RE offset relocs\n",
+			 sec_name, sec->num_info);
+
+		for_each_btf_ext_rec(seg, sec, i, rec) {
+			err = bpf_core_reloc_field(prog, rec, i, obj->btf,
+						   targ_btf, cand_cache);
+			if (err) {
+				pr_warn("prog '%s': relo #%d: failed to relocate: %d\n",
+					sec_name, i, err);
+				goto out;
+			}
+		}
+	}
+
+out:
+	btf__free(targ_btf);
+	if (!IS_ERR_OR_NULL(cand_cache)) {
+		hashmap__for_each_entry(cand_cache, entry, i) {
+			bpf_core_free_cands(entry->value);
+		}
+		hashmap__free(cand_cache);
+	}
+	return err;
+}
+
+static int
+bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
+{
+	int err = 0;
+
+	if (obj->btf_ext->field_reloc_info.len)
+		err = bpf_core_reloc_fields(obj, targ_btf_path);
+
+	return err;
+}
+
+static int
+bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
+			struct reloc_desc *relo)
+{
+	struct bpf_insn *insn, *new_insn;
+	struct bpf_program *text;
+	size_t new_cnt;
+	int err;
+
+	if (relo->type != RELO_CALL)
+		return -LIBBPF_ERRNO__RELOC;
+
+	if (prog->idx == obj->efile.text_shndx) {
+		pr_warn("relo in .text insn %d into off %d (insn #%d)\n",
+			relo->insn_idx, relo->sym_off, relo->sym_off / 8);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+
+	if (prog->main_prog_cnt == 0) {
+		text = bpf_object__find_prog_by_idx(obj, obj->efile.text_shndx);
+		if (!text) {
+			pr_warn("no .text section found yet relo into text exist\n");
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		new_cnt = prog->insns_cnt + text->insns_cnt;
+		new_insn = reallocarray(prog->insns, new_cnt, sizeof(*insn));
+		if (!new_insn) {
+			pr_warn("oom in prog realloc\n");
+			return -ENOMEM;
+		}
+		prog->insns = new_insn;
+
+		if (obj->btf_ext) {
+			err = bpf_program_reloc_btf_ext(prog, obj,
+							text->section_name,
+							prog->insns_cnt);
+			if (err)
+				return err;
+		}
+
+		memcpy(new_insn + prog->insns_cnt, text->insns,
+		       text->insns_cnt * sizeof(*insn));
+		prog->main_prog_cnt = prog->insns_cnt;
+		prog->insns_cnt = new_cnt;
+		pr_debug("added %zd insn from %s to prog %s\n",
+			 text->insns_cnt, text->section_name,
+			 prog->section_name);
+	}
+	insn = &prog->insns[relo->insn_idx];
+	insn->imm += relo->sym_off / 8 + prog->main_prog_cnt - relo->insn_idx;
+	return 0;
+}
+
+static int
+bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
+{
+	int i, err;
+
+	if (!prog)
+		return 0;
+
+	if (obj->btf_ext) {
+		err = bpf_program_reloc_btf_ext(prog, obj,
+						prog->section_name, 0);
+		if (err)
+			return err;
+	}
+
+	if (!prog->reloc_desc)
+		return 0;
+
+	for (i = 0; i < prog->nr_reloc; i++) {
+		struct reloc_desc *relo = &prog->reloc_desc[i];
+
+		if (relo->type == RELO_LD64 || relo->type == RELO_DATA) {
+			struct bpf_insn *insn = &prog->insns[relo->insn_idx];
+
+			if (relo->insn_idx + 1 >= (int)prog->insns_cnt) {
+				pr_warn("relocation out of range: '%s'\n",
+					prog->section_name);
+				return -LIBBPF_ERRNO__RELOC;
+			}
+
+			if (relo->type != RELO_DATA) {
+				insn[0].src_reg = BPF_PSEUDO_MAP_FD;
+			} else {
+				insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
+				insn[1].imm = insn[0].imm + relo->sym_off;
+			}
+			insn[0].imm = obj->maps[relo->map_idx].fd;
+		} else if (relo->type == RELO_CALL) {
+			err = bpf_program__reloc_text(prog, obj, relo);
+			if (err)
+				return err;
+		}
+	}
+
+	zfree(&prog->reloc_desc);
+	prog->nr_reloc = 0;
+	return 0;
+}
+
+static int
+bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
+{
+	struct bpf_program *prog;
+	size_t i;
+	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;
+		}
+	}
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+
+		err = bpf_program__relocate(prog, obj);
+		if (err) {
+			pr_warn("failed to relocate '%s'\n", prog->section_name);
+			return err;
+		}
+	}
+	return 0;
+}
+
+static int bpf_object__collect_reloc(struct bpf_object *obj)
+{
+	int i, err;
+
+	if (!obj_elf_valid(obj)) {
+		pr_warn("Internal error: elf object is closed\n");
+		return -LIBBPF_ERRNO__INTERNAL;
+	}
+
+	for (i = 0; i < obj->efile.nr_reloc_sects; i++) {
+		GElf_Shdr *shdr = &obj->efile.reloc_sects[i].shdr;
+		Elf_Data *data = obj->efile.reloc_sects[i].data;
+		int idx = shdr->sh_info;
+		struct bpf_program *prog;
+
+		if (shdr->sh_type != SHT_REL) {
+			pr_warn("internal error at %d\n", __LINE__);
+			return -LIBBPF_ERRNO__INTERNAL;
+		}
+
+		prog = bpf_object__find_prog_by_idx(obj, idx);
+		if (!prog) {
+			pr_warn("relocation failed: no section(%d)\n", idx);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+
+		err = bpf_program__collect_reloc(prog, shdr, data, obj);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int
+load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
+	     char *license, __u32 kern_version, int *pfd)
+{
+	struct bpf_load_program_attr load_attr;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int log_buf_size = BPF_LOG_BUF_SIZE;
+	char *log_buf;
+	int btf_fd, ret;
+
+	if (!insns || !insns_cnt)
+		return -EINVAL;
+
+	memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));
+	load_attr.prog_type = prog->type;
+	load_attr.expected_attach_type = prog->expected_attach_type;
+	if (prog->caps->name)
+		load_attr.name = prog->name;
+	load_attr.insns = insns;
+	load_attr.insns_cnt = insns_cnt;
+	load_attr.license = license;
+	if (prog->type == BPF_PROG_TYPE_TRACING) {
+		load_attr.attach_prog_fd = prog->attach_prog_fd;
+		load_attr.attach_btf_id = prog->attach_btf_id;
+	} else {
+		load_attr.kern_version = kern_version;
+		load_attr.prog_ifindex = prog->prog_ifindex;
+	}
+	/* if .BTF.ext was loaded, kernel supports associated BTF for prog */
+	if (prog->obj->btf_ext)
+		btf_fd = bpf_object__btf_fd(prog->obj);
+	else
+		btf_fd = -1;
+	load_attr.prog_btf_fd = btf_fd >= 0 ? btf_fd : 0;
+	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 = prog->log_level;
+	load_attr.prog_flags = prog->prog_flags;
+
+retry_load:
+	log_buf = malloc(log_buf_size);
+	if (!log_buf)
+		pr_warn("Alloc log buffer for bpf loader error, continue without log\n");
+
+	ret = bpf_load_program_xattr(&load_attr, log_buf, log_buf_size);
+
+	if (ret >= 0) {
+		if (load_attr.log_level)
+			pr_debug("verifier log:\n%s", log_buf);
+		*pfd = ret;
+		ret = 0;
+		goto out;
+	}
+
+	if (errno == ENOSPC) {
+		log_buf_size <<= 1;
+		free(log_buf);
+		goto retry_load;
+	}
+	ret = -errno;
+	cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+	pr_warn("load bpf program failed: %s\n", cp);
+
+	if (log_buf && log_buf[0] != '\0') {
+		ret = -LIBBPF_ERRNO__VERIFY;
+		pr_warn("-- BEGIN DUMP LOG ---\n");
+		pr_warn("\n%s\n", log_buf);
+		pr_warn("-- END LOG --\n");
+	} else if (load_attr.insns_cnt >= BPF_MAXINSNS) {
+		pr_warn("Program too large (%zu insns), at most %d insns\n",
+			load_attr.insns_cnt, BPF_MAXINSNS);
+		ret = -LIBBPF_ERRNO__PROG2BIG;
+	} else if (load_attr.prog_type != BPF_PROG_TYPE_KPROBE) {
+		/* Wrong program type? */
+		int fd;
+
+		load_attr.prog_type = BPF_PROG_TYPE_KPROBE;
+		load_attr.expected_attach_type = 0;
+		fd = bpf_load_program_xattr(&load_attr, NULL, 0);
+		if (fd >= 0) {
+			close(fd);
+			ret = -LIBBPF_ERRNO__PROGTYPE;
+			goto out;
+		}
+	}
+
+out:
+	free(log_buf);
+	return ret;
+}
+
+int
+bpf_program__load(struct bpf_program *prog,
+		  char *license, __u32 kern_version)
+{
+	int err = 0, fd, i;
+
+	if (prog->instances.nr < 0 || !prog->instances.fds) {
+		if (prog->preprocessor) {
+			pr_warn("Internal error: can't load program '%s'\n",
+				prog->section_name);
+			return -LIBBPF_ERRNO__INTERNAL;
+		}
+
+		prog->instances.fds = malloc(sizeof(int));
+		if (!prog->instances.fds) {
+			pr_warn("Not enough memory for BPF fds\n");
+			return -ENOMEM;
+		}
+		prog->instances.nr = 1;
+		prog->instances.fds[0] = -1;
+	}
+
+	if (!prog->preprocessor) {
+		if (prog->instances.nr != 1) {
+			pr_warn("Program '%s' is inconsistent: nr(%d) != 1\n",
+				prog->section_name, prog->instances.nr);
+		}
+		err = load_program(prog, prog->insns, prog->insns_cnt,
+				   license, kern_version, &fd);
+		if (!err)
+			prog->instances.fds[0] = fd;
+		goto out;
+	}
+
+	for (i = 0; i < prog->instances.nr; i++) {
+		struct bpf_prog_prep_result result;
+		bpf_program_prep_t preprocessor = prog->preprocessor;
+
+		memset(&result, 0, sizeof(result));
+		err = preprocessor(prog, i, prog->insns,
+				   prog->insns_cnt, &result);
+		if (err) {
+			pr_warn("Preprocessing the %dth instance of program '%s' failed\n",
+				i, prog->section_name);
+			goto out;
+		}
+
+		if (!result.new_insn_ptr || !result.new_insn_cnt) {
+			pr_debug("Skip loading the %dth instance of program '%s'\n",
+				 i, prog->section_name);
+			prog->instances.fds[i] = -1;
+			if (result.pfd)
+				*result.pfd = -1;
+			continue;
+		}
+
+		err = load_program(prog, result.new_insn_ptr,
+				   result.new_insn_cnt,
+				   license, kern_version, &fd);
+
+		if (err) {
+			pr_warn("Loading the %dth instance of program '%s' failed\n",
+				i, prog->section_name);
+			goto out;
+		}
+
+		if (result.pfd)
+			*result.pfd = fd;
+		prog->instances.fds[i] = fd;
+	}
+out:
+	if (err)
+		pr_warn("failed to load program '%s'\n", prog->section_name);
+	zfree(&prog->insns);
+	prog->insns_cnt = 0;
+	return err;
+}
+
+static bool bpf_program__is_function_storage(const struct bpf_program *prog,
+					     const struct bpf_object *obj)
+{
+	return prog->idx == obj->efile.text_shndx && obj->has_pseudo_calls;
+}
+
+static int
+bpf_object__load_progs(struct bpf_object *obj, int log_level)
+{
+	size_t i;
+	int err;
+
+	for (i = 0; i < obj->nr_programs; i++) {
+		if (bpf_program__is_function_storage(&obj->programs[i], obj))
+			continue;
+		obj->programs[i].log_level |= log_level;
+		err = bpf_program__load(&obj->programs[i],
+					obj->license,
+					obj->kern_version);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int libbpf_find_attach_btf_id(const char *name,
+				     enum bpf_attach_type attach_type,
+				     __u32 attach_prog_fd);
+static struct bpf_object *
+__bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
+		   struct bpf_object_open_opts *opts)
+{
+	const char *pin_root_path;
+	struct bpf_program *prog;
+	struct bpf_object *obj;
+	const char *obj_name;
+	char tmp_name[64];
+	bool relaxed_maps;
+	__u32 attach_prog_fd;
+	int err;
+
+	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);
+	}
+
+	obj = bpf_object__new(path, obj_buf, obj_buf_sz, obj_name);
+	if (IS_ERR(obj))
+		return obj;
+
+	obj->relaxed_core_relocs = OPTS_GET(opts, relaxed_core_relocs, false);
+	relaxed_maps = OPTS_GET(opts, relaxed_maps, false);
+	pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
+	attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0);
+
+	CHECK_ERR(bpf_object__elf_init(obj), err, out);
+	CHECK_ERR(bpf_object__check_endianness(obj), err, out);
+	CHECK_ERR(bpf_object__probe_caps(obj), err, out);
+	CHECK_ERR(bpf_object__elf_collect(obj, relaxed_maps, pin_root_path),
+		  err, out);
+	CHECK_ERR(bpf_object__collect_reloc(obj), err, out);
+	bpf_object__elf_finish(obj);
+
+	bpf_object__for_each_program(prog, obj) {
+		enum bpf_prog_type prog_type;
+		enum bpf_attach_type attach_type;
+
+		err = libbpf_prog_type_by_name(prog->section_name, &prog_type,
+					       &attach_type);
+		if (err == -ESRCH)
+			/* couldn't guess, but user might manually specify */
+			continue;
+		if (err)
+			goto out;
+
+		bpf_program__set_type(prog, prog_type);
+		bpf_program__set_expected_attach_type(prog, attach_type);
+		if (prog_type == BPF_PROG_TYPE_TRACING) {
+			err = libbpf_find_attach_btf_id(prog->section_name,
+							attach_type,
+							attach_prog_fd);
+			if (err <= 0)
+				goto out;
+			prog->attach_btf_id = err;
+			prog->attach_prog_fd = attach_prog_fd;
+		}
+	}
+
+	return obj;
+out:
+	bpf_object__close(obj);
+	return ERR_PTR(err);
+}
+
+static struct bpf_object *
+__bpf_object__open_xattr(struct bpf_object_open_attr *attr, int flags)
+{
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
+		.relaxed_maps = flags & MAPS_RELAX_COMPAT,
+	);
+
+	/* param validation */
+	if (!attr->file)
+		return NULL;
+
+	pr_debug("loading %s\n", attr->file);
+	return __bpf_object__open(attr->file, NULL, 0, &opts);
+}
+
+struct bpf_object *bpf_object__open_xattr(struct bpf_object_open_attr *attr)
+{
+	return __bpf_object__open_xattr(attr, 0);
+}
+
+struct bpf_object *bpf_object__open(const char *path)
+{
+	struct bpf_object_open_attr attr = {
+		.file		= path,
+		.prog_type	= BPF_PROG_TYPE_UNSPEC,
+	};
+
+	return bpf_object__open_xattr(&attr);
+}
+
+struct bpf_object *
+bpf_object__open_file(const char *path, struct bpf_object_open_opts *opts)
+{
+	if (!path)
+		return ERR_PTR(-EINVAL);
+
+	pr_debug("loading %s\n", path);
+
+	return __bpf_object__open(path, NULL, 0, opts);
+}
+
+struct bpf_object *
+bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
+		     struct bpf_object_open_opts *opts)
+{
+	if (!obj_buf || obj_buf_sz == 0)
+		return ERR_PTR(-EINVAL);
+
+	return __bpf_object__open(NULL, obj_buf, obj_buf_sz, opts);
+}
+
+struct bpf_object *
+bpf_object__open_buffer(const void *obj_buf, size_t obj_buf_sz,
+			const char *name)
+{
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
+		.object_name = name,
+		/* wrong default, but backwards-compatible */
+		.relaxed_maps = true,
+	);
+
+	/* returning NULL is wrong, but backwards-compatible */
+	if (!obj_buf || obj_buf_sz == 0)
+		return NULL;
+
+	return bpf_object__open_mem(obj_buf, obj_buf_sz, &opts);
+}
+
+int bpf_object__unload(struct bpf_object *obj)
+{
+	size_t i;
+
+	if (!obj)
+		return -EINVAL;
+
+	for (i = 0; i < obj->nr_maps; i++)
+		zclose(obj->maps[i].fd);
+
+	for (i = 0; i < obj->nr_programs; i++)
+		bpf_program__unload(&obj->programs[i]);
+
+	return 0;
+}
+
+int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
+{
+	struct bpf_object *obj;
+	int err, i;
+
+	if (!attr)
+		return -EINVAL;
+	obj = attr->obj;
+	if (!obj)
+		return -EINVAL;
+
+	if (obj->loaded) {
+		pr_warn("object should not be loaded twice\n");
+		return -EINVAL;
+	}
+
+	obj->loaded = true;
+
+	CHECK_ERR(bpf_object__create_maps(obj), err, out);
+	CHECK_ERR(bpf_object__relocate(obj, attr->target_btf_path), err, out);
+	CHECK_ERR(bpf_object__load_progs(obj, attr->log_level), err, 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 err;
+}
+
+int bpf_object__load(struct bpf_object *obj)
+{
+	struct bpf_object_load_attr attr = {
+		.obj = obj,
+	};
+
+	return bpf_object__load_xattr(&attr);
+}
+
+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_instance(struct bpf_program *prog, const char *path,
+			      int instance)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err;
+
+	err = make_parent_dir(path);
+	if (err)
+		return err;
+
+	err = check_path(path);
+	if (err)
+		return err;
+
+	if (prog == NULL) {
+		pr_warn("invalid program pointer\n");
+		return -EINVAL;
+	}
+
+	if (instance < 0 || instance >= prog->instances.nr) {
+		pr_warn("invalid prog instance %d of prog %s (max %d)\n",
+			instance, prog->section_name, prog->instances.nr);
+		return -EINVAL;
+	}
+
+	if (bpf_obj_pin(prog->instances.fds[instance], path)) {
+		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+		pr_warn("failed to pin program: %s\n", cp);
+		return -errno;
+	}
+	pr_debug("pinned program '%s'\n", path);
+
+	return 0;
+}
+
+int bpf_program__unpin_instance(struct bpf_program *prog, const char *path,
+				int instance)
+{
+	int err;
+
+	err = check_path(path);
+	if (err)
+		return err;
+
+	if (prog == NULL) {
+		pr_warn("invalid program pointer\n");
+		return -EINVAL;
+	}
+
+	if (instance < 0 || instance >= prog->instances.nr) {
+		pr_warn("invalid prog instance %d of prog %s (max %d)\n",
+			instance, prog->section_name, prog->instances.nr);
+		return -EINVAL;
+	}
+
+	err = unlink(path);
+	if (err != 0)
+		return -errno;
+	pr_debug("unpinned program '%s'\n", path);
+
+	return 0;
+}
+
+int bpf_program__pin(struct bpf_program *prog, const char *path)
+{
+	int i, err;
+
+	err = make_parent_dir(path);
+	if (err)
+		return err;
+
+	err = check_path(path);
+	if (err)
+		return err;
+
+	if (prog == NULL) {
+		pr_warn("invalid program pointer\n");
+		return -EINVAL;
+	}
+
+	if (prog->instances.nr <= 0) {
+		pr_warn("no instances of prog %s to pin\n",
+			   prog->section_name);
+		return -EINVAL;
+	}
+
+	if (prog->instances.nr == 1) {
+		/* don't create subdirs when pinning single instance */
+		return bpf_program__pin_instance(prog, path, 0);
+	}
+
+	for (i = 0; i < prog->instances.nr; i++) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%d", path, i);
+		if (len < 0) {
+			err = -EINVAL;
+			goto err_unpin;
+		} else if (len >= PATH_MAX) {
+			err = -ENAMETOOLONG;
+			goto err_unpin;
+		}
+
+		err = bpf_program__pin_instance(prog, buf, i);
+		if (err)
+			goto err_unpin;
+	}
+
+	return 0;
+
+err_unpin:
+	for (i = i - 1; i >= 0; i--) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%d", path, i);
+		if (len < 0)
+			continue;
+		else if (len >= PATH_MAX)
+			continue;
+
+		bpf_program__unpin_instance(prog, buf, i);
+	}
+
+	rmdir(path);
+
+	return err;
+}
+
+int bpf_program__unpin(struct bpf_program *prog, const char *path)
+{
+	int i, err;
+
+	err = check_path(path);
+	if (err)
+		return err;
+
+	if (prog == NULL) {
+		pr_warn("invalid program pointer\n");
+		return -EINVAL;
+	}
+
+	if (prog->instances.nr <= 0) {
+		pr_warn("no instances of prog %s to pin\n",
+			   prog->section_name);
+		return -EINVAL;
+	}
+
+	if (prog->instances.nr == 1) {
+		/* don't create subdirs when pinning single instance */
+		return bpf_program__unpin_instance(prog, path, 0);
+	}
+
+	for (i = 0; i < prog->instances.nr; i++) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%d", path, i);
+		if (len < 0)
+			return -EINVAL;
+		else if (len >= PATH_MAX)
+			return -ENAMETOOLONG;
+
+		err = bpf_program__unpin_instance(prog, buf, i);
+		if (err)
+			return err;
+	}
+
+	err = rmdir(path);
+	if (err)
+		return -errno;
+
+	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 -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 -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 -EINVAL;
+		} else if (map->pinned) {
+			pr_warn("map '%s' already pinned\n", bpf_map__name(map));
+			return -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 err;
+
+	err = check_path(map->pin_path);
+	if (err)
+		return 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 err;
+}
+
+int bpf_map__unpin(struct bpf_map *map, const char *path)
+{
+	int err;
+
+	if (map == NULL) {
+		pr_warn("invalid map pointer\n");
+		return -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 -EINVAL;
+		}
+		path = map->pin_path;
+	} else if (!path) {
+		pr_warn("no path to unpin map '%s' from\n",
+			bpf_map__name(map));
+		return -EINVAL;
+	}
+
+	err = check_path(path);
+	if (err)
+		return err;
+
+	err = unlink(path);
+	if (err != 0)
+		return -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 -errno;
+	}
+
+	free(map->pin_path);
+	map->pin_path = new;
+	return 0;
+}
+
+const char *bpf_map__get_pin_path(const struct bpf_map *map)
+{
+	return map->pin_path;
+}
+
+bool bpf_map__is_pinned(const struct bpf_map *map)
+{
+	return map->pinned;
+}
+
+int bpf_object__pin_maps(struct bpf_object *obj, const char *path)
+{
+	struct bpf_map *map;
+	int err;
+
+	if (!obj)
+		return -ENOENT;
+
+	if (!obj->loaded) {
+		pr_warn("object not yet loaded; load it first\n");
+		return -ENOENT;
+	}
+
+	bpf_object__for_each_map(map, obj) {
+		char *pin_path = NULL;
+		char buf[PATH_MAX];
+
+		if (path) {
+			int len;
+
+			len = snprintf(buf, PATH_MAX, "%s/%s", path,
+				       bpf_map__name(map));
+			if (len < 0) {
+				err = -EINVAL;
+				goto err_unpin_maps;
+			} else if (len >= PATH_MAX) {
+				err = -ENAMETOOLONG;
+				goto err_unpin_maps;
+			}
+			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_map__prev(map, obj))) {
+		if (!map->pin_path)
+			continue;
+
+		bpf_map__unpin(map, NULL);
+	}
+
+	return err;
+}
+
+int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
+{
+	struct bpf_map *map;
+	int err;
+
+	if (!obj)
+		return -ENOENT;
+
+	bpf_object__for_each_map(map, obj) {
+		char *pin_path = NULL;
+		char buf[PATH_MAX];
+
+		if (path) {
+			int len;
+
+			len = snprintf(buf, PATH_MAX, "%s/%s", path,
+				       bpf_map__name(map));
+			if (len < 0)
+				return -EINVAL;
+			else if (len >= PATH_MAX)
+				return -ENAMETOOLONG;
+			pin_path = buf;
+		} else if (!map->pin_path) {
+			continue;
+		}
+
+		err = bpf_map__unpin(map, pin_path);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
+{
+	struct bpf_program *prog;
+	int err;
+
+	if (!obj)
+		return -ENOENT;
+
+	if (!obj->loaded) {
+		pr_warn("object not yet loaded; load it first\n");
+		return -ENOENT;
+	}
+
+	bpf_object__for_each_program(prog, obj) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%s", path,
+			       prog->pin_name);
+		if (len < 0) {
+			err = -EINVAL;
+			goto err_unpin_programs;
+		} else if (len >= PATH_MAX) {
+			err = -ENAMETOOLONG;
+			goto err_unpin_programs;
+		}
+
+		err = bpf_program__pin(prog, buf);
+		if (err)
+			goto err_unpin_programs;
+	}
+
+	return 0;
+
+err_unpin_programs:
+	while ((prog = bpf_program__prev(prog, obj))) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%s", path,
+			       prog->pin_name);
+		if (len < 0)
+			continue;
+		else if (len >= PATH_MAX)
+			continue;
+
+		bpf_program__unpin(prog, buf);
+	}
+
+	return err;
+}
+
+int bpf_object__unpin_programs(struct bpf_object *obj, const char *path)
+{
+	struct bpf_program *prog;
+	int err;
+
+	if (!obj)
+		return -ENOENT;
+
+	bpf_object__for_each_program(prog, obj) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%s", path,
+			       prog->pin_name);
+		if (len < 0)
+			return -EINVAL;
+		else if (len >= PATH_MAX)
+			return -ENAMETOOLONG;
+
+		err = bpf_program__unpin(prog, buf);
+		if (err)
+			return 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 err;
+
+	err = bpf_object__pin_programs(obj, path);
+	if (err) {
+		bpf_object__unpin_maps(obj, path);
+		return err;
+	}
+
+	return 0;
+}
+
+void bpf_object__close(struct bpf_object *obj)
+{
+	size_t i;
+
+	if (!obj)
+		return;
+
+	if (obj->clear_priv)
+		obj->clear_priv(obj, obj->priv);
+
+	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++) {
+		zfree(&obj->maps[i].name);
+		zfree(&obj->maps[i].pin_path);
+		if (obj->maps[i].clear_priv)
+			obj->maps[i].clear_priv(&obj->maps[i],
+						obj->maps[i].priv);
+		obj->maps[i].priv = NULL;
+		obj->maps[i].clear_priv = NULL;
+	}
+
+	zfree(&obj->sections.rodata);
+	zfree(&obj->sections.data);
+	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);
+
+	list_del(&obj->list);
+	free(obj);
+}
+
+struct bpf_object *
+bpf_object__next(struct bpf_object *prev)
+{
+	struct bpf_object *next;
+
+	if (!prev)
+		next = list_first_entry(&bpf_objects_list,
+					struct bpf_object,
+					list);
+	else
+		next = list_next_entry(prev, list);
+
+	/* Empty list is noticed here so don't need checking on entry. */
+	if (&next->list == &bpf_objects_list)
+		return NULL;
+
+	return next;
+}
+
+const char *bpf_object__name(const struct bpf_object *obj)
+{
+	return obj ? obj->name : 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_priv(struct bpf_object *obj, void *priv,
+			 bpf_object_clear_priv_t clear_priv)
+{
+	if (obj->priv && obj->clear_priv)
+		obj->clear_priv(obj, obj->priv);
+
+	obj->priv = priv;
+	obj->clear_priv = clear_priv;
+	return 0;
+}
+
+void *bpf_object__priv(const struct bpf_object *obj)
+{
+	return obj ? obj->priv : ERR_PTR(-EINVAL);
+}
+
+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 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_program__next(struct bpf_program *prev, const struct bpf_object *obj)
+{
+	struct bpf_program *prog = prev;
+
+	do {
+		prog = __bpf_program__iter(prog, obj, true);
+	} while (prog && bpf_program__is_function_storage(prog, obj));
+
+	return prog;
+}
+
+struct bpf_program *
+bpf_program__prev(struct bpf_program *next, const struct bpf_object *obj)
+{
+	struct bpf_program *prog = next;
+
+	do {
+		prog = __bpf_program__iter(prog, obj, false);
+	} while (prog && bpf_program__is_function_storage(prog, obj));
+
+	return prog;
+}
+
+int bpf_program__set_priv(struct bpf_program *prog, void *priv,
+			  bpf_program_clear_priv_t clear_priv)
+{
+	if (prog->priv && prog->clear_priv)
+		prog->clear_priv(prog, prog->priv);
+
+	prog->priv = priv;
+	prog->clear_priv = clear_priv;
+	return 0;
+}
+
+void *bpf_program__priv(const struct bpf_program *prog)
+{
+	return prog ? prog->priv : ERR_PTR(-EINVAL);
+}
+
+void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
+{
+	prog->prog_ifindex = ifindex;
+}
+
+const char *bpf_program__title(const struct bpf_program *prog, bool needs_copy)
+{
+	const char *title;
+
+	title = prog->section_name;
+	if (needs_copy) {
+		title = strdup(title);
+		if (!title) {
+			pr_warn("failed to strdup program title\n");
+			return ERR_PTR(-ENOMEM);
+		}
+	}
+
+	return title;
+}
+
+int bpf_program__fd(const struct bpf_program *prog)
+{
+	return bpf_program__nth_fd(prog, 0);
+}
+
+size_t bpf_program__size(const struct bpf_program *prog)
+{
+	return prog->insns_cnt * sizeof(struct bpf_insn);
+}
+
+int bpf_program__set_prep(struct bpf_program *prog, int nr_instances,
+			  bpf_program_prep_t prep)
+{
+	int *instances_fds;
+
+	if (nr_instances <= 0 || !prep)
+		return -EINVAL;
+
+	if (prog->instances.nr > 0 || prog->instances.fds) {
+		pr_warn("Can't set pre-processor after loading\n");
+		return -EINVAL;
+	}
+
+	instances_fds = malloc(sizeof(int) * nr_instances);
+	if (!instances_fds) {
+		pr_warn("alloc memory failed for fds\n");
+		return -ENOMEM;
+	}
+
+	/* fill all fd with -1 */
+	memset(instances_fds, -1, sizeof(int) * nr_instances);
+
+	prog->instances.nr = nr_instances;
+	prog->instances.fds = instances_fds;
+	prog->preprocessor = prep;
+	return 0;
+}
+
+int bpf_program__nth_fd(const struct bpf_program *prog, int n)
+{
+	int fd;
+
+	if (!prog)
+		return -EINVAL;
+
+	if (n >= prog->instances.nr || n < 0) {
+		pr_warn("Can't get the %dth fd from program %s: only %d instances\n",
+			n, prog->section_name, prog->instances.nr);
+		return -EINVAL;
+	}
+
+	fd = prog->instances.fds[n];
+	if (fd < 0) {
+		pr_warn("%dth instance of program '%s' is invalid\n",
+			n, prog->section_name);
+		return -ENOENT;
+	}
+
+	return fd;
+}
+
+enum bpf_prog_type bpf_program__get_type(struct bpf_program *prog)
+{
+	return prog->type;
+}
+
+void bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
+{
+	prog->type = type;
+}
+
+static bool bpf_program__is_type(const struct bpf_program *prog,
+				 enum bpf_prog_type type)
+{
+	return prog ? (prog->type == type) : false;
+}
+
+#define BPF_PROG_TYPE_FNS(NAME, TYPE)				\
+int bpf_program__set_##NAME(struct bpf_program *prog)		\
+{								\
+	if (!prog)						\
+		return -EINVAL;					\
+	bpf_program__set_type(prog, TYPE);			\
+	return 0;						\
+}								\
+								\
+bool bpf_program__is_##NAME(const struct bpf_program *prog)	\
+{								\
+	return bpf_program__is_type(prog, TYPE);		\
+}								\
+
+BPF_PROG_TYPE_FNS(socket_filter, BPF_PROG_TYPE_SOCKET_FILTER);
+BPF_PROG_TYPE_FNS(kprobe, BPF_PROG_TYPE_KPROBE);
+BPF_PROG_TYPE_FNS(sched_cls, BPF_PROG_TYPE_SCHED_CLS);
+BPF_PROG_TYPE_FNS(sched_act, BPF_PROG_TYPE_SCHED_ACT);
+BPF_PROG_TYPE_FNS(tracepoint, BPF_PROG_TYPE_TRACEPOINT);
+BPF_PROG_TYPE_FNS(raw_tracepoint, BPF_PROG_TYPE_RAW_TRACEPOINT);
+BPF_PROG_TYPE_FNS(xdp, BPF_PROG_TYPE_XDP);
+BPF_PROG_TYPE_FNS(perf_event, BPF_PROG_TYPE_PERF_EVENT);
+BPF_PROG_TYPE_FNS(tracing, BPF_PROG_TYPE_TRACING);
+
+enum bpf_attach_type
+bpf_program__get_expected_attach_type(struct bpf_program *prog)
+{
+	return prog->expected_attach_type;
+}
+
+void bpf_program__set_expected_attach_type(struct bpf_program *prog,
+					   enum bpf_attach_type type)
+{
+	prog->expected_attach_type = type;
+}
+
+#define BPF_PROG_SEC_IMPL(string, ptype, eatype, is_attachable, btf, atype) \
+	{ string, sizeof(string) - 1, ptype, eatype, is_attachable, btf, atype }
+
+/* Programs that can NOT be attached. */
+#define BPF_PROG_SEC(string, ptype) BPF_PROG_SEC_IMPL(string, ptype, 0, 0, 0, 0)
+
+/* Programs that can be attached. */
+#define BPF_APROG_SEC(string, ptype, atype) \
+	BPF_PROG_SEC_IMPL(string, ptype, 0, 1, 0, atype)
+
+/* Programs that must specify expected attach type at load time. */
+#define BPF_EAPROG_SEC(string, ptype, eatype) \
+	BPF_PROG_SEC_IMPL(string, ptype, eatype, 1, 0, eatype)
+
+/* Programs that use BTF to identify attach point */
+#define BPF_PROG_BTF(string, ptype, eatype) \
+	BPF_PROG_SEC_IMPL(string, ptype, eatype, 0, 1, 0)
+
+/* Programs that can be attached but attach type can't be identified by section
+ * name. Kept for backward compatibility.
+ */
+#define BPF_APROG_COMPAT(string, ptype) BPF_PROG_SEC(string, ptype)
+
+static const struct {
+	const char *sec;
+	size_t len;
+	enum bpf_prog_type prog_type;
+	enum bpf_attach_type expected_attach_type;
+	bool is_attachable;
+	bool is_attach_btf;
+	enum bpf_attach_type attach_type;
+} section_names[] = {
+	BPF_PROG_SEC("socket",			BPF_PROG_TYPE_SOCKET_FILTER),
+	BPF_PROG_SEC("kprobe/",			BPF_PROG_TYPE_KPROBE),
+	BPF_PROG_SEC("uprobe/",			BPF_PROG_TYPE_KPROBE),
+	BPF_PROG_SEC("kretprobe/",		BPF_PROG_TYPE_KPROBE),
+	BPF_PROG_SEC("uretprobe/",		BPF_PROG_TYPE_KPROBE),
+	BPF_PROG_SEC("classifier",		BPF_PROG_TYPE_SCHED_CLS),
+	BPF_PROG_SEC("action",			BPF_PROG_TYPE_SCHED_ACT),
+	BPF_PROG_SEC("tracepoint/",		BPF_PROG_TYPE_TRACEPOINT),
+	BPF_PROG_SEC("tp/",			BPF_PROG_TYPE_TRACEPOINT),
+	BPF_PROG_SEC("raw_tracepoint/",		BPF_PROG_TYPE_RAW_TRACEPOINT),
+	BPF_PROG_SEC("raw_tp/",			BPF_PROG_TYPE_RAW_TRACEPOINT),
+	BPF_PROG_BTF("tp_btf/",			BPF_PROG_TYPE_TRACING,
+						BPF_TRACE_RAW_TP),
+	BPF_PROG_BTF("fentry/",			BPF_PROG_TYPE_TRACING,
+						BPF_TRACE_FENTRY),
+	BPF_PROG_BTF("fexit/",			BPF_PROG_TYPE_TRACING,
+						BPF_TRACE_FEXIT),
+	BPF_PROG_SEC("xdp",			BPF_PROG_TYPE_XDP),
+	BPF_PROG_SEC("perf_event",		BPF_PROG_TYPE_PERF_EVENT),
+	BPF_PROG_SEC("lwt_in",			BPF_PROG_TYPE_LWT_IN),
+	BPF_PROG_SEC("lwt_out",			BPF_PROG_TYPE_LWT_OUT),
+	BPF_PROG_SEC("lwt_xmit",		BPF_PROG_TYPE_LWT_XMIT),
+	BPF_PROG_SEC("lwt_seg6local",		BPF_PROG_TYPE_LWT_SEG6LOCAL),
+	BPF_APROG_SEC("cgroup_skb/ingress",	BPF_PROG_TYPE_CGROUP_SKB,
+						BPF_CGROUP_INET_INGRESS),
+	BPF_APROG_SEC("cgroup_skb/egress",	BPF_PROG_TYPE_CGROUP_SKB,
+						BPF_CGROUP_INET_EGRESS),
+	BPF_APROG_COMPAT("cgroup/skb",		BPF_PROG_TYPE_CGROUP_SKB),
+	BPF_APROG_SEC("cgroup/sock",		BPF_PROG_TYPE_CGROUP_SOCK,
+						BPF_CGROUP_INET_SOCK_CREATE),
+	BPF_EAPROG_SEC("cgroup/post_bind4",	BPF_PROG_TYPE_CGROUP_SOCK,
+						BPF_CGROUP_INET4_POST_BIND),
+	BPF_EAPROG_SEC("cgroup/post_bind6",	BPF_PROG_TYPE_CGROUP_SOCK,
+						BPF_CGROUP_INET6_POST_BIND),
+	BPF_APROG_SEC("cgroup/dev",		BPF_PROG_TYPE_CGROUP_DEVICE,
+						BPF_CGROUP_DEVICE),
+	BPF_APROG_SEC("sockops",		BPF_PROG_TYPE_SOCK_OPS,
+						BPF_CGROUP_SOCK_OPS),
+	BPF_APROG_SEC("sk_skb/stream_parser",	BPF_PROG_TYPE_SK_SKB,
+						BPF_SK_SKB_STREAM_PARSER),
+	BPF_APROG_SEC("sk_skb/stream_verdict",	BPF_PROG_TYPE_SK_SKB,
+						BPF_SK_SKB_STREAM_VERDICT),
+	BPF_APROG_COMPAT("sk_skb",		BPF_PROG_TYPE_SK_SKB),
+	BPF_APROG_SEC("sk_msg",			BPF_PROG_TYPE_SK_MSG,
+						BPF_SK_MSG_VERDICT),
+	BPF_APROG_SEC("lirc_mode2",		BPF_PROG_TYPE_LIRC_MODE2,
+						BPF_LIRC_MODE2),
+	BPF_APROG_SEC("flow_dissector",		BPF_PROG_TYPE_FLOW_DISSECTOR,
+						BPF_FLOW_DISSECTOR),
+	BPF_EAPROG_SEC("cgroup/bind4",		BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET4_BIND),
+	BPF_EAPROG_SEC("cgroup/bind6",		BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET6_BIND),
+	BPF_EAPROG_SEC("cgroup/connect4",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET4_CONNECT),
+	BPF_EAPROG_SEC("cgroup/connect6",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET6_CONNECT),
+	BPF_EAPROG_SEC("cgroup/sendmsg4",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_UDP4_SENDMSG),
+	BPF_EAPROG_SEC("cgroup/sendmsg6",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_UDP6_SENDMSG),
+	BPF_EAPROG_SEC("cgroup/recvmsg4",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_UDP4_RECVMSG),
+	BPF_EAPROG_SEC("cgroup/recvmsg6",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_UDP6_RECVMSG),
+	BPF_EAPROG_SEC("cgroup/sysctl",		BPF_PROG_TYPE_CGROUP_SYSCTL,
+						BPF_CGROUP_SYSCTL),
+	BPF_EAPROG_SEC("cgroup/getsockopt",	BPF_PROG_TYPE_CGROUP_SOCKOPT,
+						BPF_CGROUP_GETSOCKOPT),
+	BPF_EAPROG_SEC("cgroup/setsockopt",	BPF_PROG_TYPE_CGROUP_SOCKOPT,
+						BPF_CGROUP_SETSOCKOPT),
+};
+
+#undef BPF_PROG_SEC_IMPL
+#undef BPF_PROG_SEC
+#undef BPF_APROG_SEC
+#undef BPF_EAPROG_SEC
+#undef BPF_APROG_COMPAT
+
+#define MAX_TYPE_NAME_SIZE 32
+
+static char *libbpf_get_type_names(bool attach_type)
+{
+	int i, len = ARRAY_SIZE(section_names) * 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_names); i++) {
+		if (attach_type && !section_names[i].is_attachable)
+			continue;
+
+		if (strlen(buf) + strlen(section_names[i].sec) + 2 > len) {
+			free(buf);
+			return NULL;
+		}
+		strcat(buf, " ");
+		strcat(buf, section_names[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)
+{
+	char *type_names;
+	int i;
+
+	if (!name)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(section_names); i++) {
+		if (strncmp(name, section_names[i].sec, section_names[i].len))
+			continue;
+		*prog_type = section_names[i].prog_type;
+		*expected_attach_type = section_names[i].expected_attach_type;
+		return 0;
+	}
+	pr_warn("failed to guess program type from ELF section '%s'\n", name);
+	type_names = libbpf_get_type_names(false);
+	if (type_names != NULL) {
+		pr_info("supported section(type) names are:%s\n", type_names);
+		free(type_names);
+	}
+
+	return -ESRCH;
+}
+
+#define BTF_PREFIX "btf_trace_"
+int libbpf_find_vmlinux_btf_id(const char *name,
+			       enum bpf_attach_type attach_type)
+{
+	struct btf *btf = bpf_core_find_kernel_btf();
+	char raw_tp_btf[128] = BTF_PREFIX;
+	char *dst = raw_tp_btf + sizeof(BTF_PREFIX) - 1;
+	const char *btf_name;
+	int err = -EINVAL;
+	__u32 kind;
+
+	if (IS_ERR(btf)) {
+		pr_warn("vmlinux BTF is not found\n");
+		return -EINVAL;
+	}
+
+	if (attach_type == BPF_TRACE_RAW_TP) {
+		/* prepend "btf_trace_" prefix per kernel convention */
+		strncat(dst, name, sizeof(raw_tp_btf) - sizeof(BTF_PREFIX));
+		btf_name = raw_tp_btf;
+		kind = BTF_KIND_TYPEDEF;
+	} else {
+		btf_name = name;
+		kind = BTF_KIND_FUNC;
+	}
+	err = btf__find_by_name_kind(btf, btf_name, kind);
+	btf__free(btf);
+	return err;
+}
+
+static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
+{
+	struct bpf_prog_info_linear *info_linear;
+	struct bpf_prog_info *info;
+	struct btf *btf = NULL;
+	int err = -EINVAL;
+
+	info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0);
+	if (IS_ERR_OR_NULL(info_linear)) {
+		pr_warn("failed get_prog_info_linear for FD %d\n",
+			attach_prog_fd);
+		return -EINVAL;
+	}
+	info = &info_linear->info;
+	if (!info->btf_id) {
+		pr_warn("The target program doesn't have BTF\n");
+		goto out;
+	}
+	if (btf__get_from_id(info->btf_id, &btf)) {
+		pr_warn("Failed to get BTF of the program\n");
+		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:
+	free(info_linear);
+	return err;
+}
+
+static int libbpf_find_attach_btf_id(const char *name,
+				     enum bpf_attach_type attach_type,
+				     __u32 attach_prog_fd)
+{
+	int i, err;
+
+	if (!name)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(section_names); i++) {
+		if (!section_names[i].is_attach_btf)
+			continue;
+		if (strncmp(name, section_names[i].sec, section_names[i].len))
+			continue;
+		if (attach_prog_fd)
+			err = libbpf_find_prog_btf_id(name + section_names[i].len,
+						      attach_prog_fd);
+		else
+			err = libbpf_find_vmlinux_btf_id(name + section_names[i].len,
+							 attach_type);
+		if (err <= 0)
+			pr_warn("%s is not found in vmlinux BTF\n", name);
+		return err;
+	}
+	pr_warn("failed to identify btf_id based on ELF section name '%s'\n", name);
+	return -ESRCH;
+}
+
+int libbpf_attach_type_by_name(const char *name,
+			       enum bpf_attach_type *attach_type)
+{
+	char *type_names;
+	int i;
+
+	if (!name)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(section_names); i++) {
+		if (strncmp(name, section_names[i].sec, section_names[i].len))
+			continue;
+		if (!section_names[i].is_attachable)
+			return -EINVAL;
+		*attach_type = section_names[i].attach_type;
+		return 0;
+	}
+	pr_warn("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_info("attachable section(type) names are:%s\n", type_names);
+		free(type_names);
+	}
+
+	return -EINVAL;
+}
+
+int bpf_map__fd(const struct bpf_map *map)
+{
+	return map ? map->fd : -EINVAL;
+}
+
+const struct bpf_map_def *bpf_map__def(const struct bpf_map *map)
+{
+	return map ? &map->def : ERR_PTR(-EINVAL);
+}
+
+const char *bpf_map__name(const struct bpf_map *map)
+{
+	return map ? map->name : NULL;
+}
+
+__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_priv(struct bpf_map *map, void *priv,
+		     bpf_map_clear_priv_t clear_priv)
+{
+	if (!map)
+		return -EINVAL;
+
+	if (map->priv) {
+		if (map->clear_priv)
+			map->clear_priv(map, map->priv);
+	}
+
+	map->priv = priv;
+	map->clear_priv = clear_priv;
+	return 0;
+}
+
+void *bpf_map__priv(const struct bpf_map *map)
+{
+	return map ? map->priv : ERR_PTR(-EINVAL);
+}
+
+bool bpf_map__is_offload_neutral(const struct bpf_map *map)
+{
+	return map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY;
+}
+
+bool bpf_map__is_internal(const struct bpf_map *map)
+{
+	return map->libbpf_type != LIBBPF_MAP_UNSPEC;
+}
+
+void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
+{
+	map->map_ifindex = ifindex;
+}
+
+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 -EINVAL;
+	}
+	if (map->inner_map_fd != -1) {
+		pr_warn("error: inner_map_fd already specified\n");
+		return -EINVAL;
+	}
+	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 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 NULL;
+	}
+
+	idx = (m - obj->maps) + i;
+	if (idx >= obj->nr_maps || idx < 0)
+		return NULL;
+	return &obj->maps[idx];
+}
+
+struct bpf_map *
+bpf_map__next(const struct bpf_map *prev, const struct bpf_object *obj)
+{
+	if (prev == NULL)
+		return obj->maps;
+
+	return __bpf_map__iter(prev, obj, 1);
+}
+
+struct bpf_map *
+bpf_map__prev(const struct bpf_map *next, const struct bpf_object *obj)
+{
+	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 (pos->name && !strcmp(pos->name, name))
+			return pos;
+	}
+	return 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));
+}
+
+struct bpf_map *
+bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset)
+{
+	return ERR_PTR(-ENOTSUP);
+}
+
+long libbpf_get_error(const void *ptr)
+{
+	return PTR_ERR_OR_ZERO(ptr);
+}
+
+int bpf_prog_load(const char *file, enum bpf_prog_type type,
+		  struct bpf_object **pobj, int *prog_fd)
+{
+	struct bpf_prog_load_attr attr;
+
+	memset(&attr, 0, sizeof(struct bpf_prog_load_attr));
+	attr.file = file;
+	attr.prog_type = type;
+	attr.expected_attach_type = 0;
+
+	return bpf_prog_load_xattr(&attr, pobj, prog_fd);
+}
+
+int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
+			struct bpf_object **pobj, int *prog_fd)
+{
+	struct bpf_object_open_attr open_attr = {};
+	struct bpf_program *prog, *first_prog = NULL;
+	struct bpf_object *obj;
+	struct bpf_map *map;
+	int err;
+
+	if (!attr)
+		return -EINVAL;
+	if (!attr->file)
+		return -EINVAL;
+
+	open_attr.file = attr->file;
+	open_attr.prog_type = attr->prog_type;
+
+	obj = bpf_object__open_xattr(&open_attr);
+	if (IS_ERR_OR_NULL(obj))
+		return -ENOENT;
+
+	bpf_object__for_each_program(prog, obj) {
+		enum bpf_attach_type attach_type = attr->expected_attach_type;
+		/*
+		 * to preserve backwards compatibility, bpf_prog_load treats
+		 * attr->prog_type, if specified, as an override to whatever
+		 * bpf_object__open guessed
+		 */
+		if (attr->prog_type != BPF_PROG_TYPE_UNSPEC) {
+			bpf_program__set_type(prog, attr->prog_type);
+			bpf_program__set_expected_attach_type(prog,
+							      attach_type);
+		}
+		if (bpf_program__get_type(prog) == BPF_PROG_TYPE_UNSPEC) {
+			/*
+			 * we haven't guessed from section name and user
+			 * didn't provide a fallback type, too bad...
+			 */
+			bpf_object__close(obj);
+			return -EINVAL;
+		}
+
+		prog->prog_ifindex = attr->ifindex;
+		prog->log_level = attr->log_level;
+		prog->prog_flags = attr->prog_flags;
+		if (!first_prog)
+			first_prog = prog;
+	}
+
+	bpf_object__for_each_map(map, obj) {
+		if (!bpf_map__is_offload_neutral(map))
+			map->map_ifindex = attr->ifindex;
+	}
+
+	if (!first_prog) {
+		pr_warn("object file doesn't contain bpf program\n");
+		bpf_object__close(obj);
+		return -ENOENT;
+	}
+
+	err = bpf_object__load(obj);
+	if (err) {
+		bpf_object__close(obj);
+		return -EINVAL;
+	}
+
+	*pobj = obj;
+	*prog_fd = bpf_program__fd(first_prog);
+	return 0;
+}
+
+struct bpf_link {
+	int (*destroy)(struct bpf_link *link);
+};
+
+int bpf_link__destroy(struct bpf_link *link)
+{
+	int err;
+
+	if (!link)
+		return 0;
+
+	err = link->destroy(link);
+	free(link);
+
+	return err;
+}
+
+struct bpf_link_fd {
+	struct bpf_link link; /* has to be at the top of struct */
+	int fd; /* hook FD */
+};
+
+static int bpf_link__destroy_perf_event(struct bpf_link *link)
+{
+	struct bpf_link_fd *l = (void *)link;
+	int err;
+
+	err = ioctl(l->fd, PERF_EVENT_IOC_DISABLE, 0);
+	if (err)
+		err = -errno;
+
+	close(l->fd);
+	return err;
+}
+
+struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
+						int pfd)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link_fd *link;
+	int prog_fd, err;
+
+	if (pfd < 0) {
+		pr_warn("program '%s': invalid perf event FD %d\n",
+			bpf_program__title(prog, false), pfd);
+		return ERR_PTR(-EINVAL);
+	}
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("program '%s': can't attach BPF program w/o FD (did you load it?)\n",
+			bpf_program__title(prog, false));
+		return ERR_PTR(-EINVAL);
+	}
+
+	link = malloc(sizeof(*link));
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+	link->link.destroy = &bpf_link__destroy_perf_event;
+	link->fd = pfd;
+
+	if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
+		err = -errno;
+		free(link);
+		pr_warn("program '%s': failed to attach to pfd %d: %s\n",
+			bpf_program__title(prog, false), pfd,
+			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return ERR_PTR(err);
+	}
+	if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
+		err = -errno;
+		free(link);
+		pr_warn("program '%s': failed to enable pfd %d: %s\n",
+			bpf_program__title(prog, false), pfd,
+			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return ERR_PTR(err);
+	}
+	return (struct bpf_link *)link;
+}
+
+/*
+ * 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");
+}
+
+static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
+				 uint64_t offset, int pid)
+{
+	struct perf_event_attr attr = {};
+	char errmsg[STRERR_BUFSIZE];
+	int type, pfd, err;
+
+	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 = sizeof(attr);
+	attr.type = type;
+	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);
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("%s perf_event_open() failed: %s\n",
+			uprobe ? "uprobe" : "kprobe",
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return err;
+	}
+	return pfd;
+}
+
+struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog,
+					    bool retprobe,
+					    const char *func_name)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int pfd, err;
+
+	pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,
+				    0 /* offset */, -1 /* pid */);
+	if (pfd < 0) {
+		pr_warn("program '%s': failed to create %s '%s' perf event: %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "kretprobe" : "kprobe", func_name,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return ERR_PTR(pfd);
+	}
+	link = bpf_program__attach_perf_event(prog, pfd);
+	if (IS_ERR(link)) {
+		close(pfd);
+		err = PTR_ERR(link);
+		pr_warn("program '%s': failed to attach to %s '%s': %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "kretprobe" : "kprobe", func_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return link;
+	}
+	return link;
+}
+
+struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
+					    bool retprobe, pid_t pid,
+					    const char *binary_path,
+					    size_t func_offset)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int pfd, err;
+
+	pfd = perf_event_open_probe(true /* uprobe */, retprobe,
+				    binary_path, func_offset, pid);
+	if (pfd < 0) {
+		pr_warn("program '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "uretprobe" : "uprobe",
+			binary_path, func_offset,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return ERR_PTR(pfd);
+	}
+	link = bpf_program__attach_perf_event(prog, pfd);
+	if (IS_ERR(link)) {
+		close(pfd);
+		err = PTR_ERR(link);
+		pr_warn("program '%s': failed to attach to %s '%s:0x%zx': %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "uretprobe" : "uprobe",
+			binary_path, func_offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return link;
+	}
+	return link;
+}
+
+static int determine_tracepoint_id(const char *tp_category,
+				   const char *tp_name)
+{
+	char file[PATH_MAX];
+	int ret;
+
+	ret = snprintf(file, sizeof(file),
+		       "/sys/kernel/debug/tracing/events/%s/%s/id",
+		       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)
+{
+	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;
+	}
+
+	attr.type = PERF_TYPE_TRACEPOINT;
+	attr.size = sizeof(attr);
+	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(struct bpf_program *prog,
+						const char *tp_category,
+						const char *tp_name)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int pfd, err;
+
+	pfd = perf_event_open_tracepoint(tp_category, tp_name);
+	if (pfd < 0) {
+		pr_warn("program '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
+			bpf_program__title(prog, false),
+			tp_category, tp_name,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return ERR_PTR(pfd);
+	}
+	link = bpf_program__attach_perf_event(prog, pfd);
+	if (IS_ERR(link)) {
+		close(pfd);
+		err = PTR_ERR(link);
+		pr_warn("program '%s': failed to attach to tracepoint '%s/%s': %s\n",
+			bpf_program__title(prog, false),
+			tp_category, tp_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return link;
+	}
+	return link;
+}
+
+static int bpf_link__destroy_fd(struct bpf_link *link)
+{
+	struct bpf_link_fd *l = (void *)link;
+
+	return close(l->fd);
+}
+
+struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
+						    const char *tp_name)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link_fd *link;
+	int prog_fd, pfd;
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("program '%s': can't attach before loaded\n",
+			bpf_program__title(prog, false));
+		return ERR_PTR(-EINVAL);
+	}
+
+	link = malloc(sizeof(*link));
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+	link->link.destroy = &bpf_link__destroy_fd;
+
+	pfd = bpf_raw_tracepoint_open(tp_name, prog_fd);
+	if (pfd < 0) {
+		pfd = -errno;
+		free(link);
+		pr_warn("program '%s': failed to attach to raw tracepoint '%s': %s\n",
+			bpf_program__title(prog, false), tp_name,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return ERR_PTR(pfd);
+	}
+	link->fd = pfd;
+	return (struct bpf_link *)link;
+}
+
+struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link_fd *link;
+	int prog_fd, pfd;
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("program '%s': can't attach before loaded\n",
+			bpf_program__title(prog, false));
+		return ERR_PTR(-EINVAL);
+	}
+
+	link = malloc(sizeof(*link));
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+	link->link.destroy = &bpf_link__destroy_fd;
+
+	pfd = bpf_raw_tracepoint_open(NULL, prog_fd);
+	if (pfd < 0) {
+		pfd = -errno;
+		free(link);
+		pr_warn("program '%s': failed to attach to trace: %s\n",
+			bpf_program__title(prog, false),
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return ERR_PTR(pfd);
+	}
+	link->fd = pfd;
+	return (struct bpf_link *)link;
+}
+
+enum bpf_perf_event_ret
+bpf_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 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;
+	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 (!pb)
+		return;
+	if (pb->cpu_bufs) {
+		for (i = 0; i < pb->cpu_cnt && pb->cpu_bufs[i]; i++) {
+			struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
+
+			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,
+				     const struct perf_buffer_opts *opts)
+{
+	struct perf_buffer_params p = {};
+	struct perf_event_attr attr = { 0, };
+
+	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 = opts ? opts->sample_cb : NULL;
+	p.lost_cb = opts ? opts->lost_cb : NULL;
+	p.ctx = opts ? opts->ctx : NULL;
+
+	return __perf_buffer__new(map_fd, page_cnt, &p);
+}
+
+struct perf_buffer *
+perf_buffer__new_raw(int map_fd, size_t page_cnt,
+		     const struct perf_buffer_raw_opts *opts)
+{
+	struct perf_buffer_params p = {};
+
+	p.attr = opts->attr;
+	p.event_cb = opts->event_cb;
+	p.ctx = opts->ctx;
+	p.cpu_cnt = opts->cpu_cnt;
+	p.cpus = opts->cpus;
+	p.map_keys = opts->map_keys;
+
+	return __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)
+{
+	struct bpf_map_info map = {};
+	char msg[STRERR_BUFSIZE];
+	struct perf_buffer *pb;
+	__u32 map_info_len;
+	int err, i;
+
+	if (page_cnt & (page_cnt - 1)) {
+		pr_warn("page count should be power of two, but is %zu\n",
+			page_cnt);
+		return ERR_PTR(-EINVAL);
+	}
+
+	map_info_len = sizeof(map);
+	err = bpf_obj_get_info_by_fd(map_fd, &map, &map_info_len);
+	if (err) {
+		err = -errno;
+		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);
+	}
+
+	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 < 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;
+	}
+
+	for (i = 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;
+
+		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[i] = 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[i].events = EPOLLIN;
+		pb->events[i].data.ptr = cpu_buf;
+		if (epoll_ctl(pb->epoll_fd, EPOLL_CTL_ADD, cpu_buf->fd,
+			      &pb->events[i]) < 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;
+		}
+	}
+
+	return pb;
+
+error:
+	if (pb)
+		perf_buffer__free(pb);
+	return ERR_PTR(err);
+}
+
+struct perf_sample_raw {
+	struct perf_event_header header;
+	uint32_t size;
+	char data[0];
+};
+
+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 = bpf_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__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);
+	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 err;
+		}
+	}
+	return cnt < 0 ? -errno : cnt;
+}
+
+struct bpf_prog_info_array_desc {
+	int	array_offset;	/* e.g. offset of jited_prog_insns */
+	int	count_offset;	/* e.g. offset of jited_prog_len */
+	int	size_offset;	/* > 0: offset of rec size,
+				 * < 0: fix size of -size_offset
+				 */
+};
+
+static struct bpf_prog_info_array_desc bpf_prog_info_array_desc[] = {
+	[BPF_PROG_INFO_JITED_INSNS] = {
+		offsetof(struct bpf_prog_info, jited_prog_insns),
+		offsetof(struct bpf_prog_info, jited_prog_len),
+		-1,
+	},
+	[BPF_PROG_INFO_XLATED_INSNS] = {
+		offsetof(struct bpf_prog_info, xlated_prog_insns),
+		offsetof(struct bpf_prog_info, xlated_prog_len),
+		-1,
+	},
+	[BPF_PROG_INFO_MAP_IDS] = {
+		offsetof(struct bpf_prog_info, map_ids),
+		offsetof(struct bpf_prog_info, nr_map_ids),
+		-(int)sizeof(__u32),
+	},
+	[BPF_PROG_INFO_JITED_KSYMS] = {
+		offsetof(struct bpf_prog_info, jited_ksyms),
+		offsetof(struct bpf_prog_info, nr_jited_ksyms),
+		-(int)sizeof(__u64),
+	},
+	[BPF_PROG_INFO_JITED_FUNC_LENS] = {
+		offsetof(struct bpf_prog_info, jited_func_lens),
+		offsetof(struct bpf_prog_info, nr_jited_func_lens),
+		-(int)sizeof(__u32),
+	},
+	[BPF_PROG_INFO_FUNC_INFO] = {
+		offsetof(struct bpf_prog_info, func_info),
+		offsetof(struct bpf_prog_info, nr_func_info),
+		offsetof(struct bpf_prog_info, func_info_rec_size),
+	},
+	[BPF_PROG_INFO_LINE_INFO] = {
+		offsetof(struct bpf_prog_info, line_info),
+		offsetof(struct bpf_prog_info, nr_line_info),
+		offsetof(struct bpf_prog_info, line_info_rec_size),
+	},
+	[BPF_PROG_INFO_JITED_LINE_INFO] = {
+		offsetof(struct bpf_prog_info, jited_line_info),
+		offsetof(struct bpf_prog_info, nr_jited_line_info),
+		offsetof(struct bpf_prog_info, jited_line_info_rec_size),
+	},
+	[BPF_PROG_INFO_PROG_TAGS] = {
+		offsetof(struct bpf_prog_info, prog_tags),
+		offsetof(struct bpf_prog_info, nr_prog_tags),
+		-(int)sizeof(__u8) * BPF_TAG_SIZE,
+	},
+
+};
+
+static __u32 bpf_prog_info_read_offset_u32(struct bpf_prog_info *info,
+					   int offset)
+{
+	__u32 *array = (__u32 *)info;
+
+	if (offset >= 0)
+		return array[offset / sizeof(__u32)];
+	return -(int)offset;
+}
+
+static __u64 bpf_prog_info_read_offset_u64(struct bpf_prog_info *info,
+					   int offset)
+{
+	__u64 *array = (__u64 *)info;
+
+	if (offset >= 0)
+		return array[offset / sizeof(__u64)];
+	return -(int)offset;
+}
+
+static void bpf_prog_info_set_offset_u32(struct bpf_prog_info *info, int offset,
+					 __u32 val)
+{
+	__u32 *array = (__u32 *)info;
+
+	if (offset >= 0)
+		array[offset / sizeof(__u32)] = val;
+}
+
+static void bpf_prog_info_set_offset_u64(struct bpf_prog_info *info, int offset,
+					 __u64 val)
+{
+	__u64 *array = (__u64 *)info;
+
+	if (offset >= 0)
+		array[offset / sizeof(__u64)] = val;
+}
+
+struct bpf_prog_info_linear *
+bpf_program__get_prog_info_linear(int fd, __u64 arrays)
+{
+	struct bpf_prog_info_linear *info_linear;
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
+	__u32 data_len = 0;
+	int i, err;
+	void *ptr;
+
+	if (arrays >> BPF_PROG_INFO_LAST_ARRAY)
+		return ERR_PTR(-EINVAL);
+
+	/* step 1: get array dimensions */
+	err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
+	if (err) {
+		pr_debug("can't get prog info: %s", strerror(errno));
+		return ERR_PTR(-EFAULT);
+	}
+
+	/* step 2: calculate total size of all arrays */
+	for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
+		bool include_array = (arrays & (1UL << i)) > 0;
+		struct bpf_prog_info_array_desc *desc;
+		__u32 count, size;
+
+		desc = bpf_prog_info_array_desc + i;
+
+		/* kernel is too old to support this field */
+		if (info_len < desc->array_offset + sizeof(__u32) ||
+		    info_len < desc->count_offset + sizeof(__u32) ||
+		    (desc->size_offset > 0 && info_len < desc->size_offset))
+			include_array = false;
+
+		if (!include_array) {
+			arrays &= ~(1UL << i);	/* clear the bit */
+			continue;
+		}
+
+		count = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
+		size  = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
+
+		data_len += count * size;
+	}
+
+	/* step 3: allocate continuous memory */
+	data_len = roundup(data_len, sizeof(__u64));
+	info_linear = malloc(sizeof(struct bpf_prog_info_linear) + data_len);
+	if (!info_linear)
+		return ERR_PTR(-ENOMEM);
+
+	/* step 4: fill data to info_linear->info */
+	info_linear->arrays = arrays;
+	memset(&info_linear->info, 0, sizeof(info));
+	ptr = info_linear->data;
+
+	for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
+		struct bpf_prog_info_array_desc *desc;
+		__u32 count, size;
+
+		if ((arrays & (1UL << i)) == 0)
+			continue;
+
+		desc  = bpf_prog_info_array_desc + i;
+		count = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
+		size  = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
+		bpf_prog_info_set_offset_u32(&info_linear->info,
+					     desc->count_offset, count);
+		bpf_prog_info_set_offset_u32(&info_linear->info,
+					     desc->size_offset, size);
+		bpf_prog_info_set_offset_u64(&info_linear->info,
+					     desc->array_offset,
+					     ptr_to_u64(ptr));
+		ptr += count * size;
+	}
+
+	/* step 5: call syscall again to get required arrays */
+	err = bpf_obj_get_info_by_fd(fd, &info_linear->info, &info_len);
+	if (err) {
+		pr_debug("can't get prog info: %s", strerror(errno));
+		free(info_linear);
+		return ERR_PTR(-EFAULT);
+	}
+
+	/* step 6: verify the data */
+	for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
+		struct bpf_prog_info_array_desc *desc;
+		__u32 v1, v2;
+
+		if ((arrays & (1UL << i)) == 0)
+			continue;
+
+		desc = bpf_prog_info_array_desc + i;
+		v1 = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
+		v2 = bpf_prog_info_read_offset_u32(&info_linear->info,
+						   desc->count_offset);
+		if (v1 != v2)
+			pr_warn("%s: mismatch in element count\n", __func__);
+
+		v1 = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
+		v2 = bpf_prog_info_read_offset_u32(&info_linear->info,
+						   desc->size_offset);
+		if (v1 != v2)
+			pr_warn("%s: mismatch in rec size\n", __func__);
+	}
+
+	/* step 7: update info_len and data_len */
+	info_linear->info_len = sizeof(struct bpf_prog_info);
+	info_linear->data_len = data_len;
+
+	return info_linear;
+}
+
+void bpf_program__bpil_addr_to_offs(struct bpf_prog_info_linear *info_linear)
+{
+	int i;
+
+	for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
+		struct bpf_prog_info_array_desc *desc;
+		__u64 addr, offs;
+
+		if ((info_linear->arrays & (1UL << i)) == 0)
+			continue;
+
+		desc = bpf_prog_info_array_desc + i;
+		addr = bpf_prog_info_read_offset_u64(&info_linear->info,
+						     desc->array_offset);
+		offs = addr - ptr_to_u64(info_linear->data);
+		bpf_prog_info_set_offset_u64(&info_linear->info,
+					     desc->array_offset, offs);
+	}
+}
+
+void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear)
+{
+	int i;
+
+	for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
+		struct bpf_prog_info_array_desc *desc;
+		__u64 addr, offs;
+
+		if ((info_linear->arrays & (1UL << i)) == 0)
+			continue;
+
+		desc = bpf_prog_info_array_desc + i;
+		offs = bpf_prog_info_read_offset_u64(&info_linear->info,
+						     desc->array_offset);
+		addr = offs + ptr_to_u64(info_linear->data);
+		bpf_prog_info_set_offset_u64(&info_linear->info,
+					     desc->array_offset, addr);
+	}
+}
+
+int libbpf_num_possible_cpus(void)
+{
+	static const char *fcpu = "/sys/devices/system/cpu/possible";
+	int len = 0, n = 0, il = 0, ir = 0;
+	unsigned int start = 0, end = 0;
+	int tmp_cpus = 0;
+	static int cpus;
+	char buf[128];
+	int error = 0;
+	int fd = -1;
+
+	tmp_cpus = READ_ONCE(cpus);
+	if (tmp_cpus > 0)
+		return tmp_cpus;
+
+	fd = open(fcpu, O_RDONLY);
+	if (fd < 0) {
+		error = errno;
+		pr_warn("Failed to open file %s: %s\n", fcpu, strerror(error));
+		return -error;
+	}
+	len = read(fd, buf, sizeof(buf));
+	close(fd);
+	if (len <= 0) {
+		error = len ? errno : EINVAL;
+		pr_warn("Failed to read # of possible cpus from %s: %s\n",
+			fcpu, strerror(error));
+		return -error;
+	}
+	if (len == sizeof(buf)) {
+		pr_warn("File %s size overflow\n", fcpu);
+		return -EOVERFLOW;
+	}
+	buf[len] = '\0';
+
+	for (ir = 0, tmp_cpus = 0; ir <= len; ir++) {
+		/* Each sub string separated by ',' has format \d+-\d+ or \d+ */
+		if (buf[ir] == ',' || buf[ir] == '\0') {
+			buf[ir] = '\0';
+			n = sscanf(&buf[il], "%u-%u", &start, &end);
+			if (n <= 0) {
+				pr_warn("Failed to get # CPUs from %s\n",
+					&buf[il]);
+				return -EINVAL;
+			} else if (n == 1) {
+				end = start;
+			}
+			tmp_cpus += end - start + 1;
+			il = ir + 1;
+		}
+	}
+	if (tmp_cpus <= 0) {
+		pr_warn("Invalid #CPUs %d from %s\n", tmp_cpus, fcpu);
+		return -EINVAL;
+	}
+
+	WRITE_ONCE(cpus, tmp_cpus);
+	return tmp_cpus;
+}