Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 12446 insertions, 0 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
new file mode 100644
index 000000000..10f15a3e3
--- /dev/null
+++ b/tools/lib/bpf/libbpf.c
@@ -0,0 +1,12446 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * Common eBPF ELF object loading operations.
+ *
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ * Copyright (C) 2017 Nicira, Inc.
+ * Copyright (C) 2019 Isovalent, Inc.
+ */
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <libgen.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <string.h>
+#include <unistd.h>
+#include <endian.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <ctype.h>
+#include <asm/unistd.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/filter.h>
+#include <linux/limits.h>
+#include <linux/perf_event.h>
+#include <linux/ring_buffer.h>
+#include <linux/version.h>
+#include <sys/epoll.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/vfs.h>
+#include <sys/utsname.h>
+#include <sys/resource.h>
+#include <libelf.h>
+#include <gelf.h>
+#include <zlib.h>
+
+#include "libbpf.h"
+#include "bpf.h"
+#include "btf.h"
+#include "str_error.h"
+#include "libbpf_internal.h"
+#include "hashmap.h"
+#include "bpf_gen_internal.h"
+
+#ifndef BPF_FS_MAGIC
+#define BPF_FS_MAGIC		0xcafe4a11
+#endif
+
+#define BPF_INSN_SZ (sizeof(struct bpf_insn))
+
+/* vsprintf() in __base_pr() uses nonliteral format string. It may break
+ * compilation if user enables corresponding warning. Disable it explicitly.
+ */
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
+
+#define __printf(a, b)	__attribute__((format(printf, a, b)))
+
+static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
+static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
+
+static const char * const attach_type_name[] = {
+	[BPF_CGROUP_INET_INGRESS]	= "cgroup_inet_ingress",
+	[BPF_CGROUP_INET_EGRESS]	= "cgroup_inet_egress",
+	[BPF_CGROUP_INET_SOCK_CREATE]	= "cgroup_inet_sock_create",
+	[BPF_CGROUP_INET_SOCK_RELEASE]	= "cgroup_inet_sock_release",
+	[BPF_CGROUP_SOCK_OPS]		= "cgroup_sock_ops",
+	[BPF_CGROUP_DEVICE]		= "cgroup_device",
+	[BPF_CGROUP_INET4_BIND]		= "cgroup_inet4_bind",
+	[BPF_CGROUP_INET6_BIND]		= "cgroup_inet6_bind",
+	[BPF_CGROUP_INET4_CONNECT]	= "cgroup_inet4_connect",
+	[BPF_CGROUP_INET6_CONNECT]	= "cgroup_inet6_connect",
+	[BPF_CGROUP_INET4_POST_BIND]	= "cgroup_inet4_post_bind",
+	[BPF_CGROUP_INET6_POST_BIND]	= "cgroup_inet6_post_bind",
+	[BPF_CGROUP_INET4_GETPEERNAME]	= "cgroup_inet4_getpeername",
+	[BPF_CGROUP_INET6_GETPEERNAME]	= "cgroup_inet6_getpeername",
+	[BPF_CGROUP_INET4_GETSOCKNAME]	= "cgroup_inet4_getsockname",
+	[BPF_CGROUP_INET6_GETSOCKNAME]	= "cgroup_inet6_getsockname",
+	[BPF_CGROUP_UDP4_SENDMSG]	= "cgroup_udp4_sendmsg",
+	[BPF_CGROUP_UDP6_SENDMSG]	= "cgroup_udp6_sendmsg",
+	[BPF_CGROUP_SYSCTL]		= "cgroup_sysctl",
+	[BPF_CGROUP_UDP4_RECVMSG]	= "cgroup_udp4_recvmsg",
+	[BPF_CGROUP_UDP6_RECVMSG]	= "cgroup_udp6_recvmsg",
+	[BPF_CGROUP_GETSOCKOPT]		= "cgroup_getsockopt",
+	[BPF_CGROUP_SETSOCKOPT]		= "cgroup_setsockopt",
+	[BPF_SK_SKB_STREAM_PARSER]	= "sk_skb_stream_parser",
+	[BPF_SK_SKB_STREAM_VERDICT]	= "sk_skb_stream_verdict",
+	[BPF_SK_SKB_VERDICT]		= "sk_skb_verdict",
+	[BPF_SK_MSG_VERDICT]		= "sk_msg_verdict",
+	[BPF_LIRC_MODE2]		= "lirc_mode2",
+	[BPF_FLOW_DISSECTOR]		= "flow_dissector",
+	[BPF_TRACE_RAW_TP]		= "trace_raw_tp",
+	[BPF_TRACE_FENTRY]		= "trace_fentry",
+	[BPF_TRACE_FEXIT]		= "trace_fexit",
+	[BPF_MODIFY_RETURN]		= "modify_return",
+	[BPF_LSM_MAC]			= "lsm_mac",
+	[BPF_LSM_CGROUP]		= "lsm_cgroup",
+	[BPF_SK_LOOKUP]			= "sk_lookup",
+	[BPF_TRACE_ITER]		= "trace_iter",
+	[BPF_XDP_DEVMAP]		= "xdp_devmap",
+	[BPF_XDP_CPUMAP]		= "xdp_cpumap",
+	[BPF_XDP]			= "xdp",
+	[BPF_SK_REUSEPORT_SELECT]	= "sk_reuseport_select",
+	[BPF_SK_REUSEPORT_SELECT_OR_MIGRATE]	= "sk_reuseport_select_or_migrate",
+	[BPF_PERF_EVENT]		= "perf_event",
+	[BPF_TRACE_KPROBE_MULTI]	= "trace_kprobe_multi",
+};
+
+static const char * const link_type_name[] = {
+	[BPF_LINK_TYPE_UNSPEC]			= "unspec",
+	[BPF_LINK_TYPE_RAW_TRACEPOINT]		= "raw_tracepoint",
+	[BPF_LINK_TYPE_TRACING]			= "tracing",
+	[BPF_LINK_TYPE_CGROUP]			= "cgroup",
+	[BPF_LINK_TYPE_ITER]			= "iter",
+	[BPF_LINK_TYPE_NETNS]			= "netns",
+	[BPF_LINK_TYPE_XDP]			= "xdp",
+	[BPF_LINK_TYPE_PERF_EVENT]		= "perf_event",
+	[BPF_LINK_TYPE_KPROBE_MULTI]		= "kprobe_multi",
+	[BPF_LINK_TYPE_STRUCT_OPS]		= "struct_ops",
+};
+
+static const char * const map_type_name[] = {
+	[BPF_MAP_TYPE_UNSPEC]			= "unspec",
+	[BPF_MAP_TYPE_HASH]			= "hash",
+	[BPF_MAP_TYPE_ARRAY]			= "array",
+	[BPF_MAP_TYPE_PROG_ARRAY]		= "prog_array",
+	[BPF_MAP_TYPE_PERF_EVENT_ARRAY]		= "perf_event_array",
+	[BPF_MAP_TYPE_PERCPU_HASH]		= "percpu_hash",
+	[BPF_MAP_TYPE_PERCPU_ARRAY]		= "percpu_array",
+	[BPF_MAP_TYPE_STACK_TRACE]		= "stack_trace",
+	[BPF_MAP_TYPE_CGROUP_ARRAY]		= "cgroup_array",
+	[BPF_MAP_TYPE_LRU_HASH]			= "lru_hash",
+	[BPF_MAP_TYPE_LRU_PERCPU_HASH]		= "lru_percpu_hash",
+	[BPF_MAP_TYPE_LPM_TRIE]			= "lpm_trie",
+	[BPF_MAP_TYPE_ARRAY_OF_MAPS]		= "array_of_maps",
+	[BPF_MAP_TYPE_HASH_OF_MAPS]		= "hash_of_maps",
+	[BPF_MAP_TYPE_DEVMAP]			= "devmap",
+	[BPF_MAP_TYPE_DEVMAP_HASH]		= "devmap_hash",
+	[BPF_MAP_TYPE_SOCKMAP]			= "sockmap",
+	[BPF_MAP_TYPE_CPUMAP]			= "cpumap",
+	[BPF_MAP_TYPE_XSKMAP]			= "xskmap",
+	[BPF_MAP_TYPE_SOCKHASH]			= "sockhash",
+	[BPF_MAP_TYPE_CGROUP_STORAGE]		= "cgroup_storage",
+	[BPF_MAP_TYPE_REUSEPORT_SOCKARRAY]	= "reuseport_sockarray",
+	[BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE]	= "percpu_cgroup_storage",
+	[BPF_MAP_TYPE_QUEUE]			= "queue",
+	[BPF_MAP_TYPE_STACK]			= "stack",
+	[BPF_MAP_TYPE_SK_STORAGE]		= "sk_storage",
+	[BPF_MAP_TYPE_STRUCT_OPS]		= "struct_ops",
+	[BPF_MAP_TYPE_RINGBUF]			= "ringbuf",
+	[BPF_MAP_TYPE_INODE_STORAGE]		= "inode_storage",
+	[BPF_MAP_TYPE_TASK_STORAGE]		= "task_storage",
+	[BPF_MAP_TYPE_BLOOM_FILTER]		= "bloom_filter",
+	[BPF_MAP_TYPE_USER_RINGBUF]             = "user_ringbuf",
+};
+
+static const char * const prog_type_name[] = {
+	[BPF_PROG_TYPE_UNSPEC]			= "unspec",
+	[BPF_PROG_TYPE_SOCKET_FILTER]		= "socket_filter",
+	[BPF_PROG_TYPE_KPROBE]			= "kprobe",
+	[BPF_PROG_TYPE_SCHED_CLS]		= "sched_cls",
+	[BPF_PROG_TYPE_SCHED_ACT]		= "sched_act",
+	[BPF_PROG_TYPE_TRACEPOINT]		= "tracepoint",
+	[BPF_PROG_TYPE_XDP]			= "xdp",
+	[BPF_PROG_TYPE_PERF_EVENT]		= "perf_event",
+	[BPF_PROG_TYPE_CGROUP_SKB]		= "cgroup_skb",
+	[BPF_PROG_TYPE_CGROUP_SOCK]		= "cgroup_sock",
+	[BPF_PROG_TYPE_LWT_IN]			= "lwt_in",
+	[BPF_PROG_TYPE_LWT_OUT]			= "lwt_out",
+	[BPF_PROG_TYPE_LWT_XMIT]		= "lwt_xmit",
+	[BPF_PROG_TYPE_SOCK_OPS]		= "sock_ops",
+	[BPF_PROG_TYPE_SK_SKB]			= "sk_skb",
+	[BPF_PROG_TYPE_CGROUP_DEVICE]		= "cgroup_device",
+	[BPF_PROG_TYPE_SK_MSG]			= "sk_msg",
+	[BPF_PROG_TYPE_RAW_TRACEPOINT]		= "raw_tracepoint",
+	[BPF_PROG_TYPE_CGROUP_SOCK_ADDR]	= "cgroup_sock_addr",
+	[BPF_PROG_TYPE_LWT_SEG6LOCAL]		= "lwt_seg6local",
+	[BPF_PROG_TYPE_LIRC_MODE2]		= "lirc_mode2",
+	[BPF_PROG_TYPE_SK_REUSEPORT]		= "sk_reuseport",
+	[BPF_PROG_TYPE_FLOW_DISSECTOR]		= "flow_dissector",
+	[BPF_PROG_TYPE_CGROUP_SYSCTL]		= "cgroup_sysctl",
+	[BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE]	= "raw_tracepoint_writable",
+	[BPF_PROG_TYPE_CGROUP_SOCKOPT]		= "cgroup_sockopt",
+	[BPF_PROG_TYPE_TRACING]			= "tracing",
+	[BPF_PROG_TYPE_STRUCT_OPS]		= "struct_ops",
+	[BPF_PROG_TYPE_EXT]			= "ext",
+	[BPF_PROG_TYPE_LSM]			= "lsm",
+	[BPF_PROG_TYPE_SK_LOOKUP]		= "sk_lookup",
+	[BPF_PROG_TYPE_SYSCALL]			= "syscall",
+};
+
+static int __base_pr(enum libbpf_print_level level, const char *format,
+		     va_list args)
+{
+	if (level == LIBBPF_DEBUG)
+		return 0;
+
+	return vfprintf(stderr, format, args);
+}
+
+static libbpf_print_fn_t __libbpf_pr = __base_pr;
+
+libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn)
+{
+	libbpf_print_fn_t old_print_fn = __libbpf_pr;
+
+	__libbpf_pr = fn;
+	return old_print_fn;
+}
+
+__printf(2, 3)
+void libbpf_print(enum libbpf_print_level level, const char *format, ...)
+{
+	va_list args;
+	int old_errno;
+
+	if (!__libbpf_pr)
+		return;
+
+	old_errno = errno;
+
+	va_start(args, format);
+	__libbpf_pr(level, format, args);
+	va_end(args);
+
+	errno = old_errno;
+}
+
+static void pr_perm_msg(int err)
+{
+	struct rlimit limit;
+	char buf[100];
+
+	if (err != -EPERM || geteuid() != 0)
+		return;
+
+	err = getrlimit(RLIMIT_MEMLOCK, &limit);
+	if (err)
+		return;
+
+	if (limit.rlim_cur == RLIM_INFINITY)
+		return;
+
+	if (limit.rlim_cur < 1024)
+		snprintf(buf, sizeof(buf), "%zu bytes", (size_t)limit.rlim_cur);
+	else if (limit.rlim_cur < 1024*1024)
+		snprintf(buf, sizeof(buf), "%.1f KiB", (double)limit.rlim_cur / 1024);
+	else
+		snprintf(buf, sizeof(buf), "%.1f MiB", (double)limit.rlim_cur / (1024*1024));
+
+	pr_warn("permission error while running as root; try raising 'ulimit -l'? current value: %s\n",
+		buf);
+}
+
+#define STRERR_BUFSIZE  128
+
+/* Copied from tools/perf/util/util.h */
+#ifndef zfree
+# define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
+#endif
+
+#ifndef zclose
+# define zclose(fd) ({			\
+	int ___err = 0;			\
+	if ((fd) >= 0)			\
+		___err = close((fd));	\
+	fd = -1;			\
+	___err; })
+#endif
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64) (unsigned long) ptr;
+}
+
+int libbpf_set_strict_mode(enum libbpf_strict_mode mode)
+{
+	/* as of v1.0 libbpf_set_strict_mode() is a no-op */
+	return 0;
+}
+
+__u32 libbpf_major_version(void)
+{
+	return LIBBPF_MAJOR_VERSION;
+}
+
+__u32 libbpf_minor_version(void)
+{
+	return LIBBPF_MINOR_VERSION;
+}
+
+const char *libbpf_version_string(void)
+{
+#define __S(X) #X
+#define _S(X) __S(X)
+	return  "v" _S(LIBBPF_MAJOR_VERSION) "." _S(LIBBPF_MINOR_VERSION);
+#undef _S
+#undef __S
+}
+
+enum reloc_type {
+	RELO_LD64,
+	RELO_CALL,
+	RELO_DATA,
+	RELO_EXTERN_VAR,
+	RELO_EXTERN_FUNC,
+	RELO_SUBPROG_ADDR,
+	RELO_CORE,
+};
+
+struct reloc_desc {
+	enum reloc_type type;
+	int insn_idx;
+	union {
+		const struct bpf_core_relo *core_relo; /* used when type == RELO_CORE */
+		struct {
+			int map_idx;
+			int sym_off;
+		};
+	};
+};
+
+/* stored as sec_def->cookie for all libbpf-supported SEC()s */
+enum sec_def_flags {
+	SEC_NONE = 0,
+	/* expected_attach_type is optional, if kernel doesn't support that */
+	SEC_EXP_ATTACH_OPT = 1,
+	/* legacy, only used by libbpf_get_type_names() and
+	 * libbpf_attach_type_by_name(), not used by libbpf itself at all.
+	 * This used to be associated with cgroup (and few other) BPF programs
+	 * that were attachable through BPF_PROG_ATTACH command. Pretty
+	 * meaningless nowadays, though.
+	 */
+	SEC_ATTACHABLE = 2,
+	SEC_ATTACHABLE_OPT = SEC_ATTACHABLE | SEC_EXP_ATTACH_OPT,
+	/* attachment target is specified through BTF ID in either kernel or
+	 * other BPF program's BTF object */
+	SEC_ATTACH_BTF = 4,
+	/* BPF program type allows sleeping/blocking in kernel */
+	SEC_SLEEPABLE = 8,
+	/* BPF program support non-linear XDP buffer */
+	SEC_XDP_FRAGS = 16,
+};
+
+struct bpf_sec_def {
+	char *sec;
+	enum bpf_prog_type prog_type;
+	enum bpf_attach_type expected_attach_type;
+	long cookie;
+	int handler_id;
+
+	libbpf_prog_setup_fn_t prog_setup_fn;
+	libbpf_prog_prepare_load_fn_t prog_prepare_load_fn;
+	libbpf_prog_attach_fn_t prog_attach_fn;
+};
+
+/*
+ * bpf_prog should be a better name but it has been used in
+ * linux/filter.h.
+ */
+struct bpf_program {
+	char *name;
+	char *sec_name;
+	size_t sec_idx;
+	const struct bpf_sec_def *sec_def;
+	/* this program's instruction offset (in number of instructions)
+	 * within its containing ELF section
+	 */
+	size_t sec_insn_off;
+	/* number of original instructions in ELF section belonging to this
+	 * program, not taking into account subprogram instructions possible
+	 * appended later during relocation
+	 */
+	size_t sec_insn_cnt;
+	/* Offset (in number of instructions) of the start of instruction
+	 * belonging to this BPF program  within its containing main BPF
+	 * program. For the entry-point (main) BPF program, this is always
+	 * zero. For a sub-program, this gets reset before each of main BPF
+	 * programs are processed and relocated and is used to determined
+	 * whether sub-program was already appended to the main program, and
+	 * if yes, at which instruction offset.
+	 */
+	size_t sub_insn_off;
+
+	/* instructions that belong to BPF program; insns[0] is located at
+	 * sec_insn_off instruction within its ELF section in ELF file, so
+	 * when mapping ELF file instruction index to the local instruction,
+	 * one needs to subtract sec_insn_off; and vice versa.
+	 */
+	struct bpf_insn *insns;
+	/* actual number of instruction in this BPF program's image; for
+	 * entry-point BPF programs this includes the size of main program
+	 * itself plus all the used sub-programs, appended at the end
+	 */
+	size_t insns_cnt;
+
+	struct reloc_desc *reloc_desc;
+	int nr_reloc;
+
+	/* BPF verifier log settings */
+	char *log_buf;
+	size_t log_size;
+	__u32 log_level;
+
+	struct bpf_object *obj;
+
+	int fd;
+	bool autoload;
+	bool autoattach;
+	bool mark_btf_static;
+	enum bpf_prog_type type;
+	enum bpf_attach_type expected_attach_type;
+
+	int prog_ifindex;
+	__u32 attach_btf_obj_fd;
+	__u32 attach_btf_id;
+	__u32 attach_prog_fd;
+
+	void *func_info;
+	__u32 func_info_rec_size;
+	__u32 func_info_cnt;
+
+	void *line_info;
+	__u32 line_info_rec_size;
+	__u32 line_info_cnt;
+	__u32 prog_flags;
+};
+
+struct bpf_struct_ops {
+	const char *tname;
+	const struct btf_type *type;
+	struct bpf_program **progs;
+	__u32 *kern_func_off;
+	/* e.g. struct tcp_congestion_ops in bpf_prog's btf format */
+	void *data;
+	/* e.g. struct bpf_struct_ops_tcp_congestion_ops in
+	 *      btf_vmlinux's format.
+	 * struct bpf_struct_ops_tcp_congestion_ops {
+	 *	[... some other kernel fields ...]
+	 *	struct tcp_congestion_ops data;
+	 * }
+	 * kern_vdata-size == sizeof(struct bpf_struct_ops_tcp_congestion_ops)
+	 * bpf_map__init_kern_struct_ops() will populate the "kern_vdata"
+	 * from "data".
+	 */
+	void *kern_vdata;
+	__u32 type_id;
+};
+
+#define DATA_SEC ".data"
+#define BSS_SEC ".bss"
+#define RODATA_SEC ".rodata"
+#define KCONFIG_SEC ".kconfig"
+#define KSYMS_SEC ".ksyms"
+#define STRUCT_OPS_SEC ".struct_ops"
+
+enum libbpf_map_type {
+	LIBBPF_MAP_UNSPEC,
+	LIBBPF_MAP_DATA,
+	LIBBPF_MAP_BSS,
+	LIBBPF_MAP_RODATA,
+	LIBBPF_MAP_KCONFIG,
+};
+
+struct bpf_map_def {
+	unsigned int type;
+	unsigned int key_size;
+	unsigned int value_size;
+	unsigned int max_entries;
+	unsigned int map_flags;
+};
+
+struct bpf_map {
+	struct bpf_object *obj;
+	char *name;
+	/* real_name is defined for special internal maps (.rodata*,
+	 * .data*, .bss, .kconfig) and preserves their original ELF section
+	 * name. This is important to be be able to find corresponding BTF
+	 * DATASEC information.
+	 */
+	char *real_name;
+	int fd;
+	int sec_idx;
+	size_t sec_offset;
+	int map_ifindex;
+	int inner_map_fd;
+	struct bpf_map_def def;
+	__u32 numa_node;
+	__u32 btf_var_idx;
+	__u32 btf_key_type_id;
+	__u32 btf_value_type_id;
+	__u32 btf_vmlinux_value_type_id;
+	enum libbpf_map_type libbpf_type;
+	void *mmaped;
+	struct bpf_struct_ops *st_ops;
+	struct bpf_map *inner_map;
+	void **init_slots;
+	int init_slots_sz;
+	char *pin_path;
+	bool pinned;
+	bool reused;
+	bool autocreate;
+	__u64 map_extra;
+};
+
+enum extern_type {
+	EXT_UNKNOWN,
+	EXT_KCFG,
+	EXT_KSYM,
+};
+
+enum kcfg_type {
+	KCFG_UNKNOWN,
+	KCFG_CHAR,
+	KCFG_BOOL,
+	KCFG_INT,
+	KCFG_TRISTATE,
+	KCFG_CHAR_ARR,
+};
+
+struct extern_desc {
+	enum extern_type type;
+	int sym_idx;
+	int btf_id;
+	int sec_btf_id;
+	const char *name;
+	bool is_set;
+	bool is_weak;
+	union {
+		struct {
+			enum kcfg_type type;
+			int sz;
+			int align;
+			int data_off;
+			bool is_signed;
+		} kcfg;
+		struct {
+			unsigned long long addr;
+
+			/* target btf_id of the corresponding kernel var. */
+			int kernel_btf_obj_fd;
+			int kernel_btf_id;
+
+			/* local btf_id of the ksym extern's type. */
+			__u32 type_id;
+			/* BTF fd index to be patched in for insn->off, this is
+			 * 0 for vmlinux BTF, index in obj->fd_array for module
+			 * BTF
+			 */
+			__s16 btf_fd_idx;
+		} ksym;
+	};
+};
+
+struct module_btf {
+	struct btf *btf;
+	char *name;
+	__u32 id;
+	int fd;
+	int fd_array_idx;
+};
+
+enum sec_type {
+	SEC_UNUSED = 0,
+	SEC_RELO,
+	SEC_BSS,
+	SEC_DATA,
+	SEC_RODATA,
+};
+
+struct elf_sec_desc {
+	enum sec_type sec_type;
+	Elf64_Shdr *shdr;
+	Elf_Data *data;
+};
+
+struct elf_state {
+	int fd;
+	const void *obj_buf;
+	size_t obj_buf_sz;
+	Elf *elf;
+	Elf64_Ehdr *ehdr;
+	Elf_Data *symbols;
+	Elf_Data *st_ops_data;
+	size_t shstrndx; /* section index for section name strings */
+	size_t strtabidx;
+	struct elf_sec_desc *secs;
+	size_t sec_cnt;
+	int btf_maps_shndx;
+	__u32 btf_maps_sec_btf_id;
+	int text_shndx;
+	int symbols_shndx;
+	int st_ops_shndx;
+};
+
+struct usdt_manager;
+
+struct bpf_object {
+	char name[BPF_OBJ_NAME_LEN];
+	char license[64];
+	__u32 kern_version;
+
+	struct bpf_program *programs;
+	size_t nr_programs;
+	struct bpf_map *maps;
+	size_t nr_maps;
+	size_t maps_cap;
+
+	char *kconfig;
+	struct extern_desc *externs;
+	int nr_extern;
+	int kconfig_map_idx;
+
+	bool loaded;
+	bool has_subcalls;
+	bool has_rodata;
+
+	struct bpf_gen *gen_loader;
+
+	/* Information when doing ELF related work. Only valid if efile.elf is not NULL */
+	struct elf_state efile;
+
+	struct btf *btf;
+	struct btf_ext *btf_ext;
+
+	/* Parse and load BTF vmlinux if any of the programs in the object need
+	 * it at load time.
+	 */
+	struct btf *btf_vmlinux;
+	/* Path to the custom BTF to be used for BPF CO-RE relocations as an
+	 * override for vmlinux BTF.
+	 */
+	char *btf_custom_path;
+	/* vmlinux BTF override for CO-RE relocations */
+	struct btf *btf_vmlinux_override;
+	/* Lazily initialized kernel module BTFs */
+	struct module_btf *btf_modules;
+	bool btf_modules_loaded;
+	size_t btf_module_cnt;
+	size_t btf_module_cap;
+
+	/* optional log settings passed to BPF_BTF_LOAD and BPF_PROG_LOAD commands */
+	char *log_buf;
+	size_t log_size;
+	__u32 log_level;
+
+	int *fd_array;
+	size_t fd_array_cap;
+	size_t fd_array_cnt;
+
+	struct usdt_manager *usdt_man;
+
+	char path[];
+};
+
+static const char *elf_sym_str(const struct bpf_object *obj, size_t off);
+static const char *elf_sec_str(const struct bpf_object *obj, size_t off);
+static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx);
+static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name);
+static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn);
+static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn);
+static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn);
+static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx);
+static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx);
+
+void bpf_program__unload(struct bpf_program *prog)
+{
+	if (!prog)
+		return;
+
+	zclose(prog->fd);
+
+	zfree(&prog->func_info);
+	zfree(&prog->line_info);
+}
+
+static void bpf_program__exit(struct bpf_program *prog)
+{
+	if (!prog)
+		return;
+
+	bpf_program__unload(prog);
+	zfree(&prog->name);
+	zfree(&prog->sec_name);
+	zfree(&prog->insns);
+	zfree(&prog->reloc_desc);
+
+	prog->nr_reloc = 0;
+	prog->insns_cnt = 0;
+	prog->sec_idx = -1;
+}
+
+static bool insn_is_subprog_call(const struct bpf_insn *insn)
+{
+	return BPF_CLASS(insn->code) == BPF_JMP &&
+	       BPF_OP(insn->code) == BPF_CALL &&
+	       BPF_SRC(insn->code) == BPF_K &&
+	       insn->src_reg == BPF_PSEUDO_CALL &&
+	       insn->dst_reg == 0 &&
+	       insn->off == 0;
+}
+
+static bool is_call_insn(const struct bpf_insn *insn)
+{
+	return insn->code == (BPF_JMP | BPF_CALL);
+}
+
+static bool insn_is_pseudo_func(struct bpf_insn *insn)
+{
+	return is_ldimm64_insn(insn) && insn->src_reg == BPF_PSEUDO_FUNC;
+}
+
+static int
+bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog,
+		      const char *name, size_t sec_idx, const char *sec_name,
+		      size_t sec_off, void *insn_data, size_t insn_data_sz)
+{
+	if (insn_data_sz == 0 || insn_data_sz % BPF_INSN_SZ || sec_off % BPF_INSN_SZ) {
+		pr_warn("sec '%s': corrupted program '%s', offset %zu, size %zu\n",
+			sec_name, name, sec_off, insn_data_sz);
+		return -EINVAL;
+	}
+
+	memset(prog, 0, sizeof(*prog));
+	prog->obj = obj;
+
+	prog->sec_idx = sec_idx;
+	prog->sec_insn_off = sec_off / BPF_INSN_SZ;
+	prog->sec_insn_cnt = insn_data_sz / BPF_INSN_SZ;
+	/* insns_cnt can later be increased by appending used subprograms */
+	prog->insns_cnt = prog->sec_insn_cnt;
+
+	prog->type = BPF_PROG_TYPE_UNSPEC;
+	prog->fd = -1;
+
+	/* libbpf's convention for SEC("?abc...") is that it's just like
+	 * SEC("abc...") but the corresponding bpf_program starts out with
+	 * autoload set to false.
+	 */
+	if (sec_name[0] == '?') {
+		prog->autoload = false;
+		/* from now on forget there was ? in section name */
+		sec_name++;
+	} else {
+		prog->autoload = true;
+	}
+
+	prog->autoattach = true;
+
+	/* inherit object's log_level */
+	prog->log_level = obj->log_level;
+
+	prog->sec_name = strdup(sec_name);
+	if (!prog->sec_name)
+		goto errout;
+
+	prog->name = strdup(name);
+	if (!prog->name)
+		goto errout;
+
+	prog->insns = malloc(insn_data_sz);
+	if (!prog->insns)
+		goto errout;
+	memcpy(prog->insns, insn_data, insn_data_sz);
+
+	return 0;
+errout:
+	pr_warn("sec '%s': failed to allocate memory for prog '%s'\n", sec_name, name);
+	bpf_program__exit(prog);
+	return -ENOMEM;
+}
+
+static int
+bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
+			 const char *sec_name, int sec_idx)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	struct bpf_program *prog, *progs;
+	void *data = sec_data->d_buf;
+	size_t sec_sz = sec_data->d_size, sec_off, prog_sz, nr_syms;
+	int nr_progs, err, i;
+	const char *name;
+	Elf64_Sym *sym;
+
+	progs = obj->programs;
+	nr_progs = obj->nr_programs;
+	nr_syms = symbols->d_size / sizeof(Elf64_Sym);
+	sec_off = 0;
+
+	for (i = 0; i < nr_syms; i++) {
+		sym = elf_sym_by_idx(obj, i);
+
+		if (sym->st_shndx != sec_idx)
+			continue;
+		if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
+			continue;
+
+		prog_sz = sym->st_size;
+		sec_off = sym->st_value;
+
+		name = elf_sym_str(obj, sym->st_name);
+		if (!name) {
+			pr_warn("sec '%s': failed to get symbol name for offset %zu\n",
+				sec_name, sec_off);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		if (sec_off + prog_sz > sec_sz) {
+			pr_warn("sec '%s': program at offset %zu crosses section boundary\n",
+				sec_name, sec_off);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		if (sec_idx != obj->efile.text_shndx && ELF64_ST_BIND(sym->st_info) == STB_LOCAL) {
+			pr_warn("sec '%s': program '%s' is static and not supported\n", sec_name, name);
+			return -ENOTSUP;
+		}
+
+		pr_debug("sec '%s': found program '%s' at insn offset %zu (%zu bytes), code size %zu insns (%zu bytes)\n",
+			 sec_name, name, sec_off / BPF_INSN_SZ, sec_off, prog_sz / BPF_INSN_SZ, prog_sz);
+
+		progs = libbpf_reallocarray(progs, nr_progs + 1, sizeof(*progs));
+		if (!progs) {
+			/*
+			 * In this case the original obj->programs
+			 * is still valid, so don't need special treat for
+			 * bpf_close_object().
+			 */
+			pr_warn("sec '%s': failed to alloc memory for new program '%s'\n",
+				sec_name, name);
+			return -ENOMEM;
+		}
+		obj->programs = progs;
+
+		prog = &progs[nr_progs];
+
+		err = bpf_object__init_prog(obj, prog, name, sec_idx, sec_name,
+					    sec_off, data + sec_off, prog_sz);
+		if (err)
+			return err;
+
+		/* if function is a global/weak symbol, but has restricted
+		 * (STV_HIDDEN or STV_INTERNAL) visibility, mark its BTF FUNC
+		 * as static to enable more permissive BPF verification mode
+		 * with more outside context available to BPF verifier
+		 */
+		if (ELF64_ST_BIND(sym->st_info) != STB_LOCAL
+		    && (ELF64_ST_VISIBILITY(sym->st_other) == STV_HIDDEN
+			|| ELF64_ST_VISIBILITY(sym->st_other) == STV_INTERNAL))
+			prog->mark_btf_static = true;
+
+		nr_progs++;
+		obj->nr_programs = nr_progs;
+	}
+
+	return 0;
+}
+
+__u32 get_kernel_version(void)
+{
+	/* On Ubuntu LINUX_VERSION_CODE doesn't correspond to info.release,
+	 * but Ubuntu provides /proc/version_signature file, as described at
+	 * https://ubuntu.com/kernel, with an example contents below, which we
+	 * can use to get a proper LINUX_VERSION_CODE.
+	 *
+	 *   Ubuntu 5.4.0-12.15-generic 5.4.8
+	 *
+	 * In the above, 5.4.8 is what kernel is actually expecting, while
+	 * uname() call will return 5.4.0 in info.release.
+	 */
+	const char *ubuntu_kver_file = "/proc/version_signature";
+	__u32 major, minor, patch;
+	struct utsname info;
+
+	if (faccessat(AT_FDCWD, ubuntu_kver_file, R_OK, AT_EACCESS) == 0) {
+		FILE *f;
+
+		f = fopen(ubuntu_kver_file, "r");
+		if (f) {
+			if (fscanf(f, "%*s %*s %d.%d.%d\n", &major, &minor, &patch) == 3) {
+				fclose(f);
+				return KERNEL_VERSION(major, minor, patch);
+			}
+			fclose(f);
+		}
+		/* something went wrong, fall back to uname() approach */
+	}
+
+	uname(&info);
+	if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3)
+		return 0;
+	return KERNEL_VERSION(major, minor, patch);
+}
+
+static const struct btf_member *
+find_member_by_offset(const struct btf_type *t, __u32 bit_offset)
+{
+	struct btf_member *m;
+	int i;
+
+	for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
+		if (btf_member_bit_offset(t, i) == bit_offset)
+			return m;
+	}
+
+	return NULL;
+}
+
+static const struct btf_member *
+find_member_by_name(const struct btf *btf, const struct btf_type *t,
+		    const char *name)
+{
+	struct btf_member *m;
+	int i;
+
+	for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
+		if (!strcmp(btf__name_by_offset(btf, m->name_off), name))
+			return m;
+	}
+
+	return NULL;
+}
+
+#define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_"
+static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
+				   const char *name, __u32 kind);
+
+static int
+find_struct_ops_kern_types(const struct btf *btf, const char *tname,
+			   const struct btf_type **type, __u32 *type_id,
+			   const struct btf_type **vtype, __u32 *vtype_id,
+			   const struct btf_member **data_member)
+{
+	const struct btf_type *kern_type, *kern_vtype;
+	const struct btf_member *kern_data_member;
+	__s32 kern_vtype_id, kern_type_id;
+	__u32 i;
+
+	kern_type_id = btf__find_by_name_kind(btf, tname, BTF_KIND_STRUCT);
+	if (kern_type_id < 0) {
+		pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n",
+			tname);
+		return kern_type_id;
+	}
+	kern_type = btf__type_by_id(btf, kern_type_id);
+
+	/* Find the corresponding "map_value" type that will be used
+	 * in map_update(BPF_MAP_TYPE_STRUCT_OPS).  For example,
+	 * find "struct bpf_struct_ops_tcp_congestion_ops" from the
+	 * btf_vmlinux.
+	 */
+	kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX,
+						tname, BTF_KIND_STRUCT);
+	if (kern_vtype_id < 0) {
+		pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n",
+			STRUCT_OPS_VALUE_PREFIX, tname);
+		return kern_vtype_id;
+	}
+	kern_vtype = btf__type_by_id(btf, kern_vtype_id);
+
+	/* Find "struct tcp_congestion_ops" from
+	 * struct bpf_struct_ops_tcp_congestion_ops {
+	 *	[ ... ]
+	 *	struct tcp_congestion_ops data;
+	 * }
+	 */
+	kern_data_member = btf_members(kern_vtype);
+	for (i = 0; i < btf_vlen(kern_vtype); i++, kern_data_member++) {
+		if (kern_data_member->type == kern_type_id)
+			break;
+	}
+	if (i == btf_vlen(kern_vtype)) {
+		pr_warn("struct_ops init_kern: struct %s data is not found in struct %s%s\n",
+			tname, STRUCT_OPS_VALUE_PREFIX, tname);
+		return -EINVAL;
+	}
+
+	*type = kern_type;
+	*type_id = kern_type_id;
+	*vtype = kern_vtype;
+	*vtype_id = kern_vtype_id;
+	*data_member = kern_data_member;
+
+	return 0;
+}
+
+static bool bpf_map__is_struct_ops(const struct bpf_map *map)
+{
+	return map->def.type == BPF_MAP_TYPE_STRUCT_OPS;
+}
+
+/* Init the map's fields that depend on kern_btf */
+static int bpf_map__init_kern_struct_ops(struct bpf_map *map,
+					 const struct btf *btf,
+					 const struct btf *kern_btf)
+{
+	const struct btf_member *member, *kern_member, *kern_data_member;
+	const struct btf_type *type, *kern_type, *kern_vtype;
+	__u32 i, kern_type_id, kern_vtype_id, kern_data_off;
+	struct bpf_struct_ops *st_ops;
+	void *data, *kern_data;
+	const char *tname;
+	int err;
+
+	st_ops = map->st_ops;
+	type = st_ops->type;
+	tname = st_ops->tname;
+	err = find_struct_ops_kern_types(kern_btf, tname,
+					 &kern_type, &kern_type_id,
+					 &kern_vtype, &kern_vtype_id,
+					 &kern_data_member);
+	if (err)
+		return err;
+
+	pr_debug("struct_ops init_kern %s: type_id:%u kern_type_id:%u kern_vtype_id:%u\n",
+		 map->name, st_ops->type_id, kern_type_id, kern_vtype_id);
+
+	map->def.value_size = kern_vtype->size;
+	map->btf_vmlinux_value_type_id = kern_vtype_id;
+
+	st_ops->kern_vdata = calloc(1, kern_vtype->size);
+	if (!st_ops->kern_vdata)
+		return -ENOMEM;
+
+	data = st_ops->data;
+	kern_data_off = kern_data_member->offset / 8;
+	kern_data = st_ops->kern_vdata + kern_data_off;
+
+	member = btf_members(type);
+	for (i = 0; i < btf_vlen(type); i++, member++) {
+		const struct btf_type *mtype, *kern_mtype;
+		__u32 mtype_id, kern_mtype_id;
+		void *mdata, *kern_mdata;
+		__s64 msize, kern_msize;
+		__u32 moff, kern_moff;
+		__u32 kern_member_idx;
+		const char *mname;
+
+		mname = btf__name_by_offset(btf, member->name_off);
+		kern_member = find_member_by_name(kern_btf, kern_type, mname);
+		if (!kern_member) {
+			pr_warn("struct_ops init_kern %s: Cannot find member %s in kernel BTF\n",
+				map->name, mname);
+			return -ENOTSUP;
+		}
+
+		kern_member_idx = kern_member - btf_members(kern_type);
+		if (btf_member_bitfield_size(type, i) ||
+		    btf_member_bitfield_size(kern_type, kern_member_idx)) {
+			pr_warn("struct_ops init_kern %s: bitfield %s is not supported\n",
+				map->name, mname);
+			return -ENOTSUP;
+		}
+
+		moff = member->offset / 8;
+		kern_moff = kern_member->offset / 8;
+
+		mdata = data + moff;
+		kern_mdata = kern_data + kern_moff;
+
+		mtype = skip_mods_and_typedefs(btf, member->type, &mtype_id);
+		kern_mtype = skip_mods_and_typedefs(kern_btf, kern_member->type,
+						    &kern_mtype_id);
+		if (BTF_INFO_KIND(mtype->info) !=
+		    BTF_INFO_KIND(kern_mtype->info)) {
+			pr_warn("struct_ops init_kern %s: Unmatched member type %s %u != %u(kernel)\n",
+				map->name, mname, BTF_INFO_KIND(mtype->info),
+				BTF_INFO_KIND(kern_mtype->info));
+			return -ENOTSUP;
+		}
+
+		if (btf_is_ptr(mtype)) {
+			struct bpf_program *prog;
+
+			prog = st_ops->progs[i];
+			if (!prog)
+				continue;
+
+			kern_mtype = skip_mods_and_typedefs(kern_btf,
+							    kern_mtype->type,
+							    &kern_mtype_id);
+
+			/* mtype->type must be a func_proto which was
+			 * guaranteed in bpf_object__collect_st_ops_relos(),
+			 * so only check kern_mtype for func_proto here.
+			 */
+			if (!btf_is_func_proto(kern_mtype)) {
+				pr_warn("struct_ops init_kern %s: kernel member %s is not a func ptr\n",
+					map->name, mname);
+				return -ENOTSUP;
+			}
+
+			prog->attach_btf_id = kern_type_id;
+			prog->expected_attach_type = kern_member_idx;
+
+			st_ops->kern_func_off[i] = kern_data_off + kern_moff;
+
+			pr_debug("struct_ops init_kern %s: func ptr %s is set to prog %s from data(+%u) to kern_data(+%u)\n",
+				 map->name, mname, prog->name, moff,
+				 kern_moff);
+
+			continue;
+		}
+
+		msize = btf__resolve_size(btf, mtype_id);
+		kern_msize = btf__resolve_size(kern_btf, kern_mtype_id);
+		if (msize < 0 || kern_msize < 0 || msize != kern_msize) {
+			pr_warn("struct_ops init_kern %s: Error in size of member %s: %zd != %zd(kernel)\n",
+				map->name, mname, (ssize_t)msize,
+				(ssize_t)kern_msize);
+			return -ENOTSUP;
+		}
+
+		pr_debug("struct_ops init_kern %s: copy %s %u bytes from data(+%u) to kern_data(+%u)\n",
+			 map->name, mname, (unsigned int)msize,
+			 moff, kern_moff);
+		memcpy(kern_mdata, mdata, msize);
+	}
+
+	return 0;
+}
+
+static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
+{
+	struct bpf_map *map;
+	size_t i;
+	int err;
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		map = &obj->maps[i];
+
+		if (!bpf_map__is_struct_ops(map))
+			continue;
+
+		err = bpf_map__init_kern_struct_ops(map, obj->btf,
+						    obj->btf_vmlinux);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int bpf_object__init_struct_ops_maps(struct bpf_object *obj)
+{
+	const struct btf_type *type, *datasec;
+	const struct btf_var_secinfo *vsi;
+	struct bpf_struct_ops *st_ops;
+	const char *tname, *var_name;
+	__s32 type_id, datasec_id;
+	const struct btf *btf;
+	struct bpf_map *map;
+	__u32 i;
+
+	if (obj->efile.st_ops_shndx == -1)
+		return 0;
+
+	btf = obj->btf;
+	datasec_id = btf__find_by_name_kind(btf, STRUCT_OPS_SEC,
+					    BTF_KIND_DATASEC);
+	if (datasec_id < 0) {
+		pr_warn("struct_ops init: DATASEC %s not found\n",
+			STRUCT_OPS_SEC);
+		return -EINVAL;
+	}
+
+	datasec = btf__type_by_id(btf, datasec_id);
+	vsi = btf_var_secinfos(datasec);
+	for (i = 0; i < btf_vlen(datasec); i++, vsi++) {
+		type = btf__type_by_id(obj->btf, vsi->type);
+		var_name = btf__name_by_offset(obj->btf, type->name_off);
+
+		type_id = btf__resolve_type(obj->btf, vsi->type);
+		if (type_id < 0) {
+			pr_warn("struct_ops init: Cannot resolve var type_id %u in DATASEC %s\n",
+				vsi->type, STRUCT_OPS_SEC);
+			return -EINVAL;
+		}
+
+		type = btf__type_by_id(obj->btf, type_id);
+		tname = btf__name_by_offset(obj->btf, type->name_off);
+		if (!tname[0]) {
+			pr_warn("struct_ops init: anonymous type is not supported\n");
+			return -ENOTSUP;
+		}
+		if (!btf_is_struct(type)) {
+			pr_warn("struct_ops init: %s is not a struct\n", tname);
+			return -EINVAL;
+		}
+
+		map = bpf_object__add_map(obj);
+		if (IS_ERR(map))
+			return PTR_ERR(map);
+
+		map->sec_idx = obj->efile.st_ops_shndx;
+		map->sec_offset = vsi->offset;
+		map->name = strdup(var_name);
+		if (!map->name)
+			return -ENOMEM;
+
+		map->def.type = BPF_MAP_TYPE_STRUCT_OPS;
+		map->def.key_size = sizeof(int);
+		map->def.value_size = type->size;
+		map->def.max_entries = 1;
+
+		map->st_ops = calloc(1, sizeof(*map->st_ops));
+		if (!map->st_ops)
+			return -ENOMEM;
+		st_ops = map->st_ops;
+		st_ops->data = malloc(type->size);
+		st_ops->progs = calloc(btf_vlen(type), sizeof(*st_ops->progs));
+		st_ops->kern_func_off = malloc(btf_vlen(type) *
+					       sizeof(*st_ops->kern_func_off));
+		if (!st_ops->data || !st_ops->progs || !st_ops->kern_func_off)
+			return -ENOMEM;
+
+		if (vsi->offset + type->size > obj->efile.st_ops_data->d_size) {
+			pr_warn("struct_ops init: var %s is beyond the end of DATASEC %s\n",
+				var_name, STRUCT_OPS_SEC);
+			return -EINVAL;
+		}
+
+		memcpy(st_ops->data,
+		       obj->efile.st_ops_data->d_buf + vsi->offset,
+		       type->size);
+		st_ops->tname = tname;
+		st_ops->type = type;
+		st_ops->type_id = type_id;
+
+		pr_debug("struct_ops init: struct %s(type_id=%u) %s found at offset %u\n",
+			 tname, type_id, var_name, vsi->offset);
+	}
+
+	return 0;
+}
+
+static struct bpf_object *bpf_object__new(const char *path,
+					  const void *obj_buf,
+					  size_t obj_buf_sz,
+					  const char *obj_name)
+{
+	struct bpf_object *obj;
+	char *end;
+
+	obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
+	if (!obj) {
+		pr_warn("alloc memory failed for %s\n", path);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	strcpy(obj->path, path);
+	if (obj_name) {
+		libbpf_strlcpy(obj->name, obj_name, sizeof(obj->name));
+	} else {
+		/* Using basename() GNU version which doesn't modify arg. */
+		libbpf_strlcpy(obj->name, basename((void *)path), sizeof(obj->name));
+		end = strchr(obj->name, '.');
+		if (end)
+			*end = 0;
+	}
+
+	obj->efile.fd = -1;
+	/*
+	 * Caller of this function should also call
+	 * bpf_object__elf_finish() after data collection to return
+	 * obj_buf to user. If not, we should duplicate the buffer to
+	 * avoid user freeing them before elf finish.
+	 */
+	obj->efile.obj_buf = obj_buf;
+	obj->efile.obj_buf_sz = obj_buf_sz;
+	obj->efile.btf_maps_shndx = -1;
+	obj->efile.st_ops_shndx = -1;
+	obj->kconfig_map_idx = -1;
+
+	obj->kern_version = get_kernel_version();
+	obj->loaded = false;
+
+	return obj;
+}
+
+static void bpf_object__elf_finish(struct bpf_object *obj)
+{
+	if (!obj->efile.elf)
+		return;
+
+	elf_end(obj->efile.elf);
+	obj->efile.elf = NULL;
+	obj->efile.symbols = NULL;
+	obj->efile.st_ops_data = NULL;
+
+	zfree(&obj->efile.secs);
+	obj->efile.sec_cnt = 0;
+	zclose(obj->efile.fd);
+	obj->efile.obj_buf = NULL;
+	obj->efile.obj_buf_sz = 0;
+}
+
+static int bpf_object__elf_init(struct bpf_object *obj)
+{
+	Elf64_Ehdr *ehdr;
+	int err = 0;
+	Elf *elf;
+
+	if (obj->efile.elf) {
+		pr_warn("elf: init internal error\n");
+		return -LIBBPF_ERRNO__LIBELF;
+	}
+
+	if (obj->efile.obj_buf_sz > 0) {
+		/* obj_buf should have been validated by bpf_object__open_mem(). */
+		elf = elf_memory((char *)obj->efile.obj_buf, obj->efile.obj_buf_sz);
+	} else {
+		obj->efile.fd = open(obj->path, O_RDONLY | O_CLOEXEC);
+		if (obj->efile.fd < 0) {
+			char errmsg[STRERR_BUFSIZE], *cp;
+
+			err = -errno;
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+			pr_warn("elf: failed to open %s: %s\n", obj->path, cp);
+			return err;
+		}
+
+		elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL);
+	}
+
+	if (!elf) {
+		pr_warn("elf: failed to open %s as ELF file: %s\n", obj->path, elf_errmsg(-1));
+		err = -LIBBPF_ERRNO__LIBELF;
+		goto errout;
+	}
+
+	obj->efile.elf = elf;
+
+	if (elf_kind(elf) != ELF_K_ELF) {
+		err = -LIBBPF_ERRNO__FORMAT;
+		pr_warn("elf: '%s' is not a proper ELF object\n", obj->path);
+		goto errout;
+	}
+
+	if (gelf_getclass(elf) != ELFCLASS64) {
+		err = -LIBBPF_ERRNO__FORMAT;
+		pr_warn("elf: '%s' is not a 64-bit ELF object\n", obj->path);
+		goto errout;
+	}
+
+	obj->efile.ehdr = ehdr = elf64_getehdr(elf);
+	if (!obj->efile.ehdr) {
+		pr_warn("elf: failed to get ELF header from %s: %s\n", obj->path, elf_errmsg(-1));
+		err = -LIBBPF_ERRNO__FORMAT;
+		goto errout;
+	}
+
+	if (elf_getshdrstrndx(elf, &obj->efile.shstrndx)) {
+		pr_warn("elf: failed to get section names section index for %s: %s\n",
+			obj->path, elf_errmsg(-1));
+		err = -LIBBPF_ERRNO__FORMAT;
+		goto errout;
+	}
+
+	/* Elf is corrupted/truncated, avoid calling elf_strptr. */
+	if (!elf_rawdata(elf_getscn(elf, obj->efile.shstrndx), NULL)) {
+		pr_warn("elf: failed to get section names strings from %s: %s\n",
+			obj->path, elf_errmsg(-1));
+		err = -LIBBPF_ERRNO__FORMAT;
+		goto errout;
+	}
+
+	/* Old LLVM set e_machine to EM_NONE */
+	if (ehdr->e_type != ET_REL || (ehdr->e_machine && ehdr->e_machine != EM_BPF)) {
+		pr_warn("elf: %s is not a valid eBPF object file\n", obj->path);
+		err = -LIBBPF_ERRNO__FORMAT;
+		goto errout;
+	}
+
+	return 0;
+errout:
+	bpf_object__elf_finish(obj);
+	return err;
+}
+
+static int bpf_object__check_endianness(struct bpf_object *obj)
+{
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
+		return 0;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+	if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
+		return 0;
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+	pr_warn("elf: endianness mismatch in %s.\n", obj->path);
+	return -LIBBPF_ERRNO__ENDIAN;
+}
+
+static int
+bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
+{
+	if (!data) {
+		pr_warn("invalid license section in %s\n", obj->path);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	/* libbpf_strlcpy() only copies first N - 1 bytes, so size + 1 won't
+	 * go over allowed ELF data section buffer
+	 */
+	libbpf_strlcpy(obj->license, data, min(size + 1, sizeof(obj->license)));
+	pr_debug("license of %s is %s\n", obj->path, obj->license);
+	return 0;
+}
+
+static int
+bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size)
+{
+	__u32 kver;
+
+	if (!data || size != sizeof(kver)) {
+		pr_warn("invalid kver section in %s\n", obj->path);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	memcpy(&kver, data, sizeof(kver));
+	obj->kern_version = kver;
+	pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version);
+	return 0;
+}
+
+static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)
+{
+	if (type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
+	    type == BPF_MAP_TYPE_HASH_OF_MAPS)
+		return true;
+	return false;
+}
+
+static int find_elf_sec_sz(const struct bpf_object *obj, const char *name, __u32 *size)
+{
+	Elf_Data *data;
+	Elf_Scn *scn;
+
+	if (!name)
+		return -EINVAL;
+
+	scn = elf_sec_by_name(obj, name);
+	data = elf_sec_data(obj, scn);
+	if (data) {
+		*size = data->d_size;
+		return 0; /* found it */
+	}
+
+	return -ENOENT;
+}
+
+static int find_elf_var_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(Elf64_Sym); si++) {
+		Elf64_Sym *sym = elf_sym_by_idx(obj, si);
+
+		if (ELF64_ST_TYPE(sym->st_info) != STT_OBJECT)
+			continue;
+
+		if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL &&
+		    ELF64_ST_BIND(sym->st_info) != STB_WEAK)
+			continue;
+
+		sname = elf_sym_str(obj, sym->st_name);
+		if (!sname) {
+			pr_warn("failed to get sym name string for var %s\n", name);
+			return -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 *map;
+	int err;
+
+	err = libbpf_ensure_mem((void **)&obj->maps, &obj->maps_cap,
+				sizeof(*obj->maps), obj->nr_maps + 1);
+	if (err)
+		return ERR_PTR(err);
+
+	map = &obj->maps[obj->nr_maps++];
+	map->obj = obj;
+	map->fd = -1;
+	map->inner_map_fd = -1;
+	map->autocreate = true;
+
+	return map;
+}
+
+static size_t bpf_map_mmap_sz(const struct bpf_map *map)
+{
+	long page_sz = sysconf(_SC_PAGE_SIZE);
+	size_t map_sz;
+
+	map_sz = (size_t)roundup(map->def.value_size, 8) * map->def.max_entries;
+	map_sz = roundup(map_sz, page_sz);
+	return map_sz;
+}
+
+static char *internal_map_name(struct bpf_object *obj, const char *real_name)
+{
+	char map_name[BPF_OBJ_NAME_LEN], *p;
+	int pfx_len, sfx_len = max((size_t)7, strlen(real_name));
+
+	/* This is one of the more confusing parts of libbpf for various
+	 * reasons, some of which are historical. The original idea for naming
+	 * internal names was to include as much of BPF object name prefix as
+	 * possible, so that it can be distinguished from similar internal
+	 * maps of a different BPF object.
+	 * As an example, let's say we have bpf_object named 'my_object_name'
+	 * and internal map corresponding to '.rodata' ELF section. The final
+	 * map name advertised to user and to the kernel will be
+	 * 'my_objec.rodata', taking first 8 characters of object name and
+	 * entire 7 characters of '.rodata'.
+	 * Somewhat confusingly, if internal map ELF section name is shorter
+	 * than 7 characters, e.g., '.bss', we still reserve 7 characters
+	 * for the suffix, even though we only have 4 actual characters, and
+	 * resulting map will be called 'my_objec.bss', not even using all 15
+	 * characters allowed by the kernel. Oh well, at least the truncated
+	 * object name is somewhat consistent in this case. But if the map
+	 * name is '.kconfig', we'll still have entirety of '.kconfig' added
+	 * (8 chars) and thus will be left with only first 7 characters of the
+	 * object name ('my_obje'). Happy guessing, user, that the final map
+	 * name will be "my_obje.kconfig".
+	 * Now, with libbpf starting to support arbitrarily named .rodata.*
+	 * and .data.* data sections, it's possible that ELF section name is
+	 * longer than allowed 15 chars, so we now need to be careful to take
+	 * only up to 15 first characters of ELF name, taking no BPF object
+	 * name characters at all. So '.rodata.abracadabra' will result in
+	 * '.rodata.abracad' kernel and user-visible name.
+	 * We need to keep this convoluted logic intact for .data, .bss and
+	 * .rodata maps, but for new custom .data.custom and .rodata.custom
+	 * maps we use their ELF names as is, not prepending bpf_object name
+	 * in front. We still need to truncate them to 15 characters for the
+	 * kernel. Full name can be recovered for such maps by using DATASEC
+	 * BTF type associated with such map's value type, though.
+	 */
+	if (sfx_len >= BPF_OBJ_NAME_LEN)
+		sfx_len = BPF_OBJ_NAME_LEN - 1;
+
+	/* if there are two or more dots in map name, it's a custom dot map */
+	if (strchr(real_name + 1, '.') != NULL)
+		pfx_len = 0;
+	else
+		pfx_len = min((size_t)BPF_OBJ_NAME_LEN - sfx_len - 1, strlen(obj->name));
+
+	snprintf(map_name, sizeof(map_name), "%.*s%.*s", pfx_len, obj->name,
+		 sfx_len, real_name);
+
+	/* sanitise map name to characters allowed by kernel */
+	for (p = map_name; *p && p < map_name + sizeof(map_name); p++)
+		if (!isalnum(*p) && *p != '_' && *p != '.')
+			*p = '_';
+
+	return strdup(map_name);
+}
+
+static int
+bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map);
+
+static int
+bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
+			      const char *real_name, int sec_idx, void *data, size_t data_sz)
+{
+	struct bpf_map_def *def;
+	struct bpf_map *map;
+	int err;
+
+	map = bpf_object__add_map(obj);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	map->libbpf_type = type;
+	map->sec_idx = sec_idx;
+	map->sec_offset = 0;
+	map->real_name = strdup(real_name);
+	map->name = internal_map_name(obj, real_name);
+	if (!map->real_name || !map->name) {
+		zfree(&map->real_name);
+		zfree(&map->name);
+		return -ENOMEM;
+	}
+
+	def = &map->def;
+	def->type = BPF_MAP_TYPE_ARRAY;
+	def->key_size = sizeof(int);
+	def->value_size = data_sz;
+	def->max_entries = 1;
+	def->map_flags = type == LIBBPF_MAP_RODATA || type == LIBBPF_MAP_KCONFIG
+			 ? BPF_F_RDONLY_PROG : 0;
+	def->map_flags |= BPF_F_MMAPABLE;
+
+	pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %x.\n",
+		 map->name, map->sec_idx, map->sec_offset, def->map_flags);
+
+	map->mmaped = mmap(NULL, bpf_map_mmap_sz(map), PROT_READ | PROT_WRITE,
+			   MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+	if (map->mmaped == MAP_FAILED) {
+		err = -errno;
+		map->mmaped = NULL;
+		pr_warn("failed to alloc map '%s' content buffer: %d\n",
+			map->name, err);
+		zfree(&map->real_name);
+		zfree(&map->name);
+		return err;
+	}
+
+	/* failures are fine because of maps like .rodata.str1.1 */
+	(void) bpf_map_find_btf_info(obj, map);
+
+	if (data)
+		memcpy(map->mmaped, data, data_sz);
+
+	pr_debug("map %td is \"%s\"\n", map - obj->maps, map->name);
+	return 0;
+}
+
+static int bpf_object__init_global_data_maps(struct bpf_object *obj)
+{
+	struct elf_sec_desc *sec_desc;
+	const char *sec_name;
+	int err = 0, sec_idx;
+
+	/*
+	 * Populate obj->maps with libbpf internal maps.
+	 */
+	for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) {
+		sec_desc = &obj->efile.secs[sec_idx];
+
+		/* Skip recognized sections with size 0. */
+		if (!sec_desc->data || sec_desc->data->d_size == 0)
+			continue;
+
+		switch (sec_desc->sec_type) {
+		case SEC_DATA:
+			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
+			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
+							    sec_name, sec_idx,
+							    sec_desc->data->d_buf,
+							    sec_desc->data->d_size);
+			break;
+		case SEC_RODATA:
+			obj->has_rodata = true;
+			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
+			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
+							    sec_name, sec_idx,
+							    sec_desc->data->d_buf,
+							    sec_desc->data->d_size);
+			break;
+		case SEC_BSS:
+			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
+			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
+							    sec_name, sec_idx,
+							    NULL,
+							    sec_desc->data->d_size);
+			break;
+		default:
+			/* skip */
+			break;
+		}
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+
+static struct extern_desc *find_extern_by_name(const struct bpf_object *obj,
+					       const void *name)
+{
+	int i;
+
+	for (i = 0; i < obj->nr_extern; i++) {
+		if (strcmp(obj->externs[i].name, name) == 0)
+			return &obj->externs[i];
+	}
+	return NULL;
+}
+
+static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val,
+			      char value)
+{
+	switch (ext->kcfg.type) {
+	case KCFG_BOOL:
+		if (value == 'm') {
+			pr_warn("extern (kcfg) '%s': value '%c' implies tristate or char type\n",
+				ext->name, value);
+			return -EINVAL;
+		}
+		*(bool *)ext_val = value == 'y' ? true : false;
+		break;
+	case KCFG_TRISTATE:
+		if (value == 'y')
+			*(enum libbpf_tristate *)ext_val = TRI_YES;
+		else if (value == 'm')
+			*(enum libbpf_tristate *)ext_val = TRI_MODULE;
+		else /* value == 'n' */
+			*(enum libbpf_tristate *)ext_val = TRI_NO;
+		break;
+	case KCFG_CHAR:
+		*(char *)ext_val = value;
+		break;
+	case KCFG_UNKNOWN:
+	case KCFG_INT:
+	case KCFG_CHAR_ARR:
+	default:
+		pr_warn("extern (kcfg) '%s': value '%c' implies bool, tristate, or char type\n",
+			ext->name, value);
+		return -EINVAL;
+	}
+	ext->is_set = true;
+	return 0;
+}
+
+static int set_kcfg_value_str(struct extern_desc *ext, char *ext_val,
+			      const char *value)
+{
+	size_t len;
+
+	if (ext->kcfg.type != KCFG_CHAR_ARR) {
+		pr_warn("extern (kcfg) '%s': value '%s' implies char array type\n",
+			ext->name, value);
+		return -EINVAL;
+	}
+
+	len = strlen(value);
+	if (value[len - 1] != '"') {
+		pr_warn("extern (kcfg) '%s': invalid string config '%s'\n",
+			ext->name, value);
+		return -EINVAL;
+	}
+
+	/* strip quotes */
+	len -= 2;
+	if (len >= ext->kcfg.sz) {
+		pr_warn("extern (kcfg) '%s': long string '%s' of (%zu bytes) truncated to %d bytes\n",
+			ext->name, value, len, ext->kcfg.sz - 1);
+		len = ext->kcfg.sz - 1;
+	}
+	memcpy(ext_val, value + 1, len);
+	ext_val[len] = '\0';
+	ext->is_set = true;
+	return 0;
+}
+
+static int parse_u64(const char *value, __u64 *res)
+{
+	char *value_end;
+	int err;
+
+	errno = 0;
+	*res = strtoull(value, &value_end, 0);
+	if (errno) {
+		err = -errno;
+		pr_warn("failed to parse '%s' as integer: %d\n", value, err);
+		return err;
+	}
+	if (*value_end) {
+		pr_warn("failed to parse '%s' as integer completely\n", value);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static bool is_kcfg_value_in_range(const struct extern_desc *ext, __u64 v)
+{
+	int bit_sz = ext->kcfg.sz * 8;
+
+	if (ext->kcfg.sz == 8)
+		return true;
+
+	/* Validate that value stored in u64 fits in integer of `ext->sz`
+	 * bytes size without any loss of information. If the target integer
+	 * is signed, we rely on the following limits of integer type of
+	 * Y bits and subsequent transformation:
+	 *
+	 *     -2^(Y-1) <= X           <= 2^(Y-1) - 1
+	 *            0 <= X + 2^(Y-1) <= 2^Y - 1
+	 *            0 <= X + 2^(Y-1) <  2^Y
+	 *
+	 *  For unsigned target integer, check that all the (64 - Y) bits are
+	 *  zero.
+	 */
+	if (ext->kcfg.is_signed)
+		return v + (1ULL << (bit_sz - 1)) < (1ULL << bit_sz);
+	else
+		return (v >> bit_sz) == 0;
+}
+
+static int set_kcfg_value_num(struct extern_desc *ext, void *ext_val,
+			      __u64 value)
+{
+	if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR &&
+	    ext->kcfg.type != KCFG_BOOL) {
+		pr_warn("extern (kcfg) '%s': value '%llu' implies integer, char, or boolean type\n",
+			ext->name, (unsigned long long)value);
+		return -EINVAL;
+	}
+	if (ext->kcfg.type == KCFG_BOOL && value > 1) {
+		pr_warn("extern (kcfg) '%s': value '%llu' isn't boolean compatible\n",
+			ext->name, (unsigned long long)value);
+		return -EINVAL;
+
+	}
+	if (!is_kcfg_value_in_range(ext, value)) {
+		pr_warn("extern (kcfg) '%s': value '%llu' doesn't fit in %d bytes\n",
+			ext->name, (unsigned long long)value, ext->kcfg.sz);
+		return -ERANGE;
+	}
+	switch (ext->kcfg.sz) {
+		case 1: *(__u8 *)ext_val = value; break;
+		case 2: *(__u16 *)ext_val = value; break;
+		case 4: *(__u32 *)ext_val = value; break;
+		case 8: *(__u64 *)ext_val = value; break;
+		default:
+			return -EINVAL;
+	}
+	ext->is_set = true;
+	return 0;
+}
+
+static int bpf_object__process_kconfig_line(struct bpf_object *obj,
+					    char *buf, void *data)
+{
+	struct extern_desc *ext;
+	char *sep, *value;
+	int len, err = 0;
+	void *ext_val;
+	__u64 num;
+
+	if (!str_has_pfx(buf, "CONFIG_"))
+		return 0;
+
+	sep = strchr(buf, '=');
+	if (!sep) {
+		pr_warn("failed to parse '%s': no separator\n", buf);
+		return -EINVAL;
+	}
+
+	/* Trim ending '\n' */
+	len = strlen(buf);
+	if (buf[len - 1] == '\n')
+		buf[len - 1] = '\0';
+	/* Split on '=' and ensure that a value is present. */
+	*sep = '\0';
+	if (!sep[1]) {
+		*sep = '=';
+		pr_warn("failed to parse '%s': no value\n", buf);
+		return -EINVAL;
+	}
+
+	ext = find_extern_by_name(obj, buf);
+	if (!ext || ext->is_set)
+		return 0;
+
+	ext_val = data + ext->kcfg.data_off;
+	value = sep + 1;
+
+	switch (*value) {
+	case 'y': case 'n': case 'm':
+		err = set_kcfg_value_tri(ext, ext_val, *value);
+		break;
+	case '"':
+		err = set_kcfg_value_str(ext, ext_val, value);
+		break;
+	default:
+		/* assume integer */
+		err = parse_u64(value, &num);
+		if (err) {
+			pr_warn("extern (kcfg) '%s': value '%s' isn't a valid integer\n", ext->name, value);
+			return err;
+		}
+		if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR) {
+			pr_warn("extern (kcfg) '%s': value '%s' implies integer type\n", ext->name, value);
+			return -EINVAL;
+		}
+		err = set_kcfg_value_num(ext, ext_val, num);
+		break;
+	}
+	if (err)
+		return err;
+	pr_debug("extern (kcfg) '%s': set to %s\n", ext->name, value);
+	return 0;
+}
+
+static int bpf_object__read_kconfig_file(struct bpf_object *obj, void *data)
+{
+	char buf[PATH_MAX];
+	struct utsname uts;
+	int len, err = 0;
+	gzFile file;
+
+	uname(&uts);
+	len = snprintf(buf, PATH_MAX, "/boot/config-%s", uts.release);
+	if (len < 0)
+		return -EINVAL;
+	else if (len >= PATH_MAX)
+		return -ENAMETOOLONG;
+
+	/* gzopen also accepts uncompressed files. */
+	file = gzopen(buf, "r");
+	if (!file)
+		file = gzopen("/proc/config.gz", "r");
+
+	if (!file) {
+		pr_warn("failed to open system Kconfig\n");
+		return -ENOENT;
+	}
+
+	while (gzgets(file, buf, sizeof(buf))) {
+		err = bpf_object__process_kconfig_line(obj, buf, data);
+		if (err) {
+			pr_warn("error parsing system Kconfig line '%s': %d\n",
+				buf, err);
+			goto out;
+		}
+	}
+
+out:
+	gzclose(file);
+	return err;
+}
+
+static int bpf_object__read_kconfig_mem(struct bpf_object *obj,
+					const char *config, void *data)
+{
+	char buf[PATH_MAX];
+	int err = 0;
+	FILE *file;
+
+	file = fmemopen((void *)config, strlen(config), "r");
+	if (!file) {
+		err = -errno;
+		pr_warn("failed to open in-memory Kconfig: %d\n", err);
+		return err;
+	}
+
+	while (fgets(buf, sizeof(buf), file)) {
+		err = bpf_object__process_kconfig_line(obj, buf, data);
+		if (err) {
+			pr_warn("error parsing in-memory Kconfig line '%s': %d\n",
+				buf, err);
+			break;
+		}
+	}
+
+	fclose(file);
+	return err;
+}
+
+static int bpf_object__init_kconfig_map(struct bpf_object *obj)
+{
+	struct extern_desc *last_ext = NULL, *ext;
+	size_t map_sz;
+	int i, err;
+
+	for (i = 0; i < obj->nr_extern; i++) {
+		ext = &obj->externs[i];
+		if (ext->type == EXT_KCFG)
+			last_ext = ext;
+	}
+
+	if (!last_ext)
+		return 0;
+
+	map_sz = last_ext->kcfg.data_off + last_ext->kcfg.sz;
+	err = bpf_object__init_internal_map(obj, LIBBPF_MAP_KCONFIG,
+					    ".kconfig", obj->efile.symbols_shndx,
+					    NULL, map_sz);
+	if (err)
+		return err;
+
+	obj->kconfig_map_idx = obj->nr_maps - 1;
+
+	return 0;
+}
+
+const struct btf_type *
+skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
+{
+	const struct btf_type *t = btf__type_by_id(btf, id);
+
+	if (res_id)
+		*res_id = id;
+
+	while (btf_is_mod(t) || btf_is_typedef(t)) {
+		if (res_id)
+			*res_id = t->type;
+		t = btf__type_by_id(btf, t->type);
+	}
+
+	return t;
+}
+
+static const struct btf_type *
+resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
+{
+	const struct btf_type *t;
+
+	t = skip_mods_and_typedefs(btf, id, NULL);
+	if (!btf_is_ptr(t))
+		return NULL;
+
+	t = skip_mods_and_typedefs(btf, t->type, res_id);
+
+	return btf_is_func_proto(t) ? t : NULL;
+}
+
+static const char *__btf_kind_str(__u16 kind)
+{
+	switch (kind) {
+	case BTF_KIND_UNKN: return "void";
+	case BTF_KIND_INT: return "int";
+	case BTF_KIND_PTR: return "ptr";
+	case BTF_KIND_ARRAY: return "array";
+	case BTF_KIND_STRUCT: return "struct";
+	case BTF_KIND_UNION: return "union";
+	case BTF_KIND_ENUM: return "enum";
+	case BTF_KIND_FWD: return "fwd";
+	case BTF_KIND_TYPEDEF: return "typedef";
+	case BTF_KIND_VOLATILE: return "volatile";
+	case BTF_KIND_CONST: return "const";
+	case BTF_KIND_RESTRICT: return "restrict";
+	case BTF_KIND_FUNC: return "func";
+	case BTF_KIND_FUNC_PROTO: return "func_proto";
+	case BTF_KIND_VAR: return "var";
+	case BTF_KIND_DATASEC: return "datasec";
+	case BTF_KIND_FLOAT: return "float";
+	case BTF_KIND_DECL_TAG: return "decl_tag";
+	case BTF_KIND_TYPE_TAG: return "type_tag";
+	case BTF_KIND_ENUM64: return "enum64";
+	default: return "unknown";
+	}
+}
+
+const char *btf_kind_str(const struct btf_type *t)
+{
+	return __btf_kind_str(btf_kind(t));
+}
+
+/*
+ * Fetch integer attribute of BTF map definition. Such attributes are
+ * represented using a pointer to an array, in which dimensionality of array
+ * encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY];
+ * encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF
+ * type definition, while using only sizeof(void *) space in ELF data section.
+ */
+static bool get_map_field_int(const char *map_name, const struct btf *btf,
+			      const struct btf_member *m, __u32 *res)
+{
+	const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL);
+	const char *name = btf__name_by_offset(btf, m->name_off);
+	const struct btf_array *arr_info;
+	const struct btf_type *arr_t;
+
+	if (!btf_is_ptr(t)) {
+		pr_warn("map '%s': attr '%s': expected PTR, got %s.\n",
+			map_name, name, btf_kind_str(t));
+		return false;
+	}
+
+	arr_t = btf__type_by_id(btf, t->type);
+	if (!arr_t) {
+		pr_warn("map '%s': attr '%s': type [%u] not found.\n",
+			map_name, name, t->type);
+		return false;
+	}
+	if (!btf_is_array(arr_t)) {
+		pr_warn("map '%s': attr '%s': expected ARRAY, got %s.\n",
+			map_name, name, btf_kind_str(arr_t));
+		return false;
+	}
+	arr_info = btf_array(arr_t);
+	*res = arr_info->nelems;
+	return true;
+}
+
+static int pathname_concat(char *buf, size_t buf_sz, const char *path, const char *name)
+{
+	int len;
+
+	len = snprintf(buf, buf_sz, "%s/%s", path, name);
+	if (len < 0)
+		return -EINVAL;
+	if (len >= buf_sz)
+		return -ENAMETOOLONG;
+
+	return 0;
+}
+
+static int build_map_pin_path(struct bpf_map *map, const char *path)
+{
+	char buf[PATH_MAX];
+	int err;
+
+	if (!path)
+		path = "/sys/fs/bpf";
+
+	err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
+	if (err)
+		return err;
+
+	return bpf_map__set_pin_path(map, buf);
+}
+
+/* should match definition in bpf_helpers.h */
+enum libbpf_pin_type {
+	LIBBPF_PIN_NONE,
+	/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
+	LIBBPF_PIN_BY_NAME,
+};
+
+int parse_btf_map_def(const char *map_name, struct btf *btf,
+		      const struct btf_type *def_t, bool strict,
+		      struct btf_map_def *map_def, struct btf_map_def *inner_def)
+{
+	const struct btf_type *t;
+	const struct btf_member *m;
+	bool is_inner = inner_def == NULL;
+	int vlen, i;
+
+	vlen = btf_vlen(def_t);
+	m = btf_members(def_t);
+	for (i = 0; i < vlen; i++, m++) {
+		const char *name = btf__name_by_offset(btf, m->name_off);
+
+		if (!name) {
+			pr_warn("map '%s': invalid field #%d.\n", map_name, i);
+			return -EINVAL;
+		}
+		if (strcmp(name, "type") == 0) {
+			if (!get_map_field_int(map_name, btf, m, &map_def->map_type))
+				return -EINVAL;
+			map_def->parts |= MAP_DEF_MAP_TYPE;
+		} else if (strcmp(name, "max_entries") == 0) {
+			if (!get_map_field_int(map_name, btf, m, &map_def->max_entries))
+				return -EINVAL;
+			map_def->parts |= MAP_DEF_MAX_ENTRIES;
+		} else if (strcmp(name, "map_flags") == 0) {
+			if (!get_map_field_int(map_name, btf, m, &map_def->map_flags))
+				return -EINVAL;
+			map_def->parts |= MAP_DEF_MAP_FLAGS;
+		} else if (strcmp(name, "numa_node") == 0) {
+			if (!get_map_field_int(map_name, btf, m, &map_def->numa_node))
+				return -EINVAL;
+			map_def->parts |= MAP_DEF_NUMA_NODE;
+		} else if (strcmp(name, "key_size") == 0) {
+			__u32 sz;
+
+			if (!get_map_field_int(map_name, btf, m, &sz))
+				return -EINVAL;
+			if (map_def->key_size && map_def->key_size != sz) {
+				pr_warn("map '%s': conflicting key size %u != %u.\n",
+					map_name, map_def->key_size, sz);
+				return -EINVAL;
+			}
+			map_def->key_size = sz;
+			map_def->parts |= MAP_DEF_KEY_SIZE;
+		} else if (strcmp(name, "key") == 0) {
+			__s64 sz;
+
+			t = btf__type_by_id(btf, m->type);
+			if (!t) {
+				pr_warn("map '%s': key type [%d] not found.\n",
+					map_name, m->type);
+				return -EINVAL;
+			}
+			if (!btf_is_ptr(t)) {
+				pr_warn("map '%s': key spec is not PTR: %s.\n",
+					map_name, btf_kind_str(t));
+				return -EINVAL;
+			}
+			sz = btf__resolve_size(btf, t->type);
+			if (sz < 0) {
+				pr_warn("map '%s': can't determine key size for type [%u]: %zd.\n",
+					map_name, t->type, (ssize_t)sz);
+				return sz;
+			}
+			if (map_def->key_size && map_def->key_size != sz) {
+				pr_warn("map '%s': conflicting key size %u != %zd.\n",
+					map_name, map_def->key_size, (ssize_t)sz);
+				return -EINVAL;
+			}
+			map_def->key_size = sz;
+			map_def->key_type_id = t->type;
+			map_def->parts |= MAP_DEF_KEY_SIZE | MAP_DEF_KEY_TYPE;
+		} else if (strcmp(name, "value_size") == 0) {
+			__u32 sz;
+
+			if (!get_map_field_int(map_name, btf, m, &sz))
+				return -EINVAL;
+			if (map_def->value_size && map_def->value_size != sz) {
+				pr_warn("map '%s': conflicting value size %u != %u.\n",
+					map_name, map_def->value_size, sz);
+				return -EINVAL;
+			}
+			map_def->value_size = sz;
+			map_def->parts |= MAP_DEF_VALUE_SIZE;
+		} else if (strcmp(name, "value") == 0) {
+			__s64 sz;
+
+			t = btf__type_by_id(btf, m->type);
+			if (!t) {
+				pr_warn("map '%s': value type [%d] not found.\n",
+					map_name, m->type);
+				return -EINVAL;
+			}
+			if (!btf_is_ptr(t)) {
+				pr_warn("map '%s': value spec is not PTR: %s.\n",
+					map_name, btf_kind_str(t));
+				return -EINVAL;
+			}
+			sz = btf__resolve_size(btf, t->type);
+			if (sz < 0) {
+				pr_warn("map '%s': can't determine value size for type [%u]: %zd.\n",
+					map_name, t->type, (ssize_t)sz);
+				return sz;
+			}
+			if (map_def->value_size && map_def->value_size != sz) {
+				pr_warn("map '%s': conflicting value size %u != %zd.\n",
+					map_name, map_def->value_size, (ssize_t)sz);
+				return -EINVAL;
+			}
+			map_def->value_size = sz;
+			map_def->value_type_id = t->type;
+			map_def->parts |= MAP_DEF_VALUE_SIZE | MAP_DEF_VALUE_TYPE;
+		}
+		else if (strcmp(name, "values") == 0) {
+			bool is_map_in_map = bpf_map_type__is_map_in_map(map_def->map_type);
+			bool is_prog_array = map_def->map_type == BPF_MAP_TYPE_PROG_ARRAY;
+			const char *desc = is_map_in_map ? "map-in-map inner" : "prog-array value";
+			char inner_map_name[128];
+			int err;
+
+			if (is_inner) {
+				pr_warn("map '%s': multi-level inner maps not supported.\n",
+					map_name);
+				return -ENOTSUP;
+			}
+			if (i != vlen - 1) {
+				pr_warn("map '%s': '%s' member should be last.\n",
+					map_name, name);
+				return -EINVAL;
+			}
+			if (!is_map_in_map && !is_prog_array) {
+				pr_warn("map '%s': should be map-in-map or prog-array.\n",
+					map_name);
+				return -ENOTSUP;
+			}
+			if (map_def->value_size && map_def->value_size != 4) {
+				pr_warn("map '%s': conflicting value size %u != 4.\n",
+					map_name, map_def->value_size);
+				return -EINVAL;
+			}
+			map_def->value_size = 4;
+			t = btf__type_by_id(btf, m->type);
+			if (!t) {
+				pr_warn("map '%s': %s type [%d] not found.\n",
+					map_name, desc, m->type);
+				return -EINVAL;
+			}
+			if (!btf_is_array(t) || btf_array(t)->nelems) {
+				pr_warn("map '%s': %s spec is not a zero-sized array.\n",
+					map_name, desc);
+				return -EINVAL;
+			}
+			t = skip_mods_and_typedefs(btf, btf_array(t)->type, NULL);
+			if (!btf_is_ptr(t)) {
+				pr_warn("map '%s': %s def is of unexpected kind %s.\n",
+					map_name, desc, btf_kind_str(t));
+				return -EINVAL;
+			}
+			t = skip_mods_and_typedefs(btf, t->type, NULL);
+			if (is_prog_array) {
+				if (!btf_is_func_proto(t)) {
+					pr_warn("map '%s': prog-array value def is of unexpected kind %s.\n",
+						map_name, btf_kind_str(t));
+					return -EINVAL;
+				}
+				continue;
+			}
+			if (!btf_is_struct(t)) {
+				pr_warn("map '%s': map-in-map inner def is of unexpected kind %s.\n",
+					map_name, btf_kind_str(t));
+				return -EINVAL;
+			}
+
+			snprintf(inner_map_name, sizeof(inner_map_name), "%s.inner", map_name);
+			err = parse_btf_map_def(inner_map_name, btf, t, strict, inner_def, NULL);
+			if (err)
+				return err;
+
+			map_def->parts |= MAP_DEF_INNER_MAP;
+		} else if (strcmp(name, "pinning") == 0) {
+			__u32 val;
+
+			if (is_inner) {
+				pr_warn("map '%s': inner def can't be pinned.\n", map_name);
+				return -EINVAL;
+			}
+			if (!get_map_field_int(map_name, btf, m, &val))
+				return -EINVAL;
+			if (val != LIBBPF_PIN_NONE && val != LIBBPF_PIN_BY_NAME) {
+				pr_warn("map '%s': invalid pinning value %u.\n",
+					map_name, val);
+				return -EINVAL;
+			}
+			map_def->pinning = val;
+			map_def->parts |= MAP_DEF_PINNING;
+		} else if (strcmp(name, "map_extra") == 0) {
+			__u32 map_extra;
+
+			if (!get_map_field_int(map_name, btf, m, &map_extra))
+				return -EINVAL;
+			map_def->map_extra = map_extra;
+			map_def->parts |= MAP_DEF_MAP_EXTRA;
+		} else {
+			if (strict) {
+				pr_warn("map '%s': unknown field '%s'.\n", map_name, name);
+				return -ENOTSUP;
+			}
+			pr_debug("map '%s': ignoring unknown field '%s'.\n", map_name, name);
+		}
+	}
+
+	if (map_def->map_type == BPF_MAP_TYPE_UNSPEC) {
+		pr_warn("map '%s': map type isn't specified.\n", map_name);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static size_t adjust_ringbuf_sz(size_t sz)
+{
+	__u32 page_sz = sysconf(_SC_PAGE_SIZE);
+	__u32 mul;
+
+	/* if user forgot to set any size, make sure they see error */
+	if (sz == 0)
+		return 0;
+	/* Kernel expects BPF_MAP_TYPE_RINGBUF's max_entries to be
+	 * a power-of-2 multiple of kernel's page size. If user diligently
+	 * satisified these conditions, pass the size through.
+	 */
+	if ((sz % page_sz) == 0 && is_pow_of_2(sz / page_sz))
+		return sz;
+
+	/* Otherwise find closest (page_sz * power_of_2) product bigger than
+	 * user-set size to satisfy both user size request and kernel
+	 * requirements and substitute correct max_entries for map creation.
+	 */
+	for (mul = 1; mul <= UINT_MAX / page_sz; mul <<= 1) {
+		if (mul * page_sz > sz)
+			return mul * page_sz;
+	}
+
+	/* if it's impossible to satisfy the conditions (i.e., user size is
+	 * very close to UINT_MAX but is not a power-of-2 multiple of
+	 * page_size) then just return original size and let kernel reject it
+	 */
+	return sz;
+}
+
+static bool map_is_ringbuf(const struct bpf_map *map)
+{
+	return map->def.type == BPF_MAP_TYPE_RINGBUF ||
+	       map->def.type == BPF_MAP_TYPE_USER_RINGBUF;
+}
+
+static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def)
+{
+	map->def.type = def->map_type;
+	map->def.key_size = def->key_size;
+	map->def.value_size = def->value_size;
+	map->def.max_entries = def->max_entries;
+	map->def.map_flags = def->map_flags;
+	map->map_extra = def->map_extra;
+
+	map->numa_node = def->numa_node;
+	map->btf_key_type_id = def->key_type_id;
+	map->btf_value_type_id = def->value_type_id;
+
+	/* auto-adjust BPF ringbuf map max_entries to be a multiple of page size */
+	if (map_is_ringbuf(map))
+		map->def.max_entries = adjust_ringbuf_sz(map->def.max_entries);
+
+	if (def->parts & MAP_DEF_MAP_TYPE)
+		pr_debug("map '%s': found type = %u.\n", map->name, def->map_type);
+
+	if (def->parts & MAP_DEF_KEY_TYPE)
+		pr_debug("map '%s': found key [%u], sz = %u.\n",
+			 map->name, def->key_type_id, def->key_size);
+	else if (def->parts & MAP_DEF_KEY_SIZE)
+		pr_debug("map '%s': found key_size = %u.\n", map->name, def->key_size);
+
+	if (def->parts & MAP_DEF_VALUE_TYPE)
+		pr_debug("map '%s': found value [%u], sz = %u.\n",
+			 map->name, def->value_type_id, def->value_size);
+	else if (def->parts & MAP_DEF_VALUE_SIZE)
+		pr_debug("map '%s': found value_size = %u.\n", map->name, def->value_size);
+
+	if (def->parts & MAP_DEF_MAX_ENTRIES)
+		pr_debug("map '%s': found max_entries = %u.\n", map->name, def->max_entries);
+	if (def->parts & MAP_DEF_MAP_FLAGS)
+		pr_debug("map '%s': found map_flags = 0x%x.\n", map->name, def->map_flags);
+	if (def->parts & MAP_DEF_MAP_EXTRA)
+		pr_debug("map '%s': found map_extra = 0x%llx.\n", map->name,
+			 (unsigned long long)def->map_extra);
+	if (def->parts & MAP_DEF_PINNING)
+		pr_debug("map '%s': found pinning = %u.\n", map->name, def->pinning);
+	if (def->parts & MAP_DEF_NUMA_NODE)
+		pr_debug("map '%s': found numa_node = %u.\n", map->name, def->numa_node);
+
+	if (def->parts & MAP_DEF_INNER_MAP)
+		pr_debug("map '%s': found inner map definition.\n", map->name);
+}
+
+static const char *btf_var_linkage_str(__u32 linkage)
+{
+	switch (linkage) {
+	case BTF_VAR_STATIC: return "static";
+	case BTF_VAR_GLOBAL_ALLOCATED: return "global";
+	case BTF_VAR_GLOBAL_EXTERN: return "extern";
+	default: return "unknown";
+	}
+}
+
+static int bpf_object__init_user_btf_map(struct bpf_object *obj,
+					 const struct btf_type *sec,
+					 int var_idx, int sec_idx,
+					 const Elf_Data *data, bool strict,
+					 const char *pin_root_path)
+{
+	struct btf_map_def map_def = {}, inner_def = {};
+	const struct btf_type *var, *def;
+	const struct btf_var_secinfo *vi;
+	const struct btf_var *var_extra;
+	const char *map_name;
+	struct bpf_map *map;
+	int err;
+
+	vi = btf_var_secinfos(sec) + var_idx;
+	var = btf__type_by_id(obj->btf, vi->type);
+	var_extra = btf_var(var);
+	map_name = btf__name_by_offset(obj->btf, var->name_off);
+
+	if (map_name == NULL || map_name[0] == '\0') {
+		pr_warn("map #%d: empty name.\n", var_idx);
+		return -EINVAL;
+	}
+	if ((__u64)vi->offset + vi->size > data->d_size) {
+		pr_warn("map '%s' BTF data is corrupted.\n", map_name);
+		return -EINVAL;
+	}
+	if (!btf_is_var(var)) {
+		pr_warn("map '%s': unexpected var kind %s.\n",
+			map_name, btf_kind_str(var));
+		return -EINVAL;
+	}
+	if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED) {
+		pr_warn("map '%s': unsupported map linkage %s.\n",
+			map_name, btf_var_linkage_str(var_extra->linkage));
+		return -EOPNOTSUPP;
+	}
+
+	def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
+	if (!btf_is_struct(def)) {
+		pr_warn("map '%s': unexpected def kind %s.\n",
+			map_name, btf_kind_str(var));
+		return -EINVAL;
+	}
+	if (def->size > vi->size) {
+		pr_warn("map '%s': invalid def size.\n", map_name);
+		return -EINVAL;
+	}
+
+	map = bpf_object__add_map(obj);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+	map->name = strdup(map_name);
+	if (!map->name) {
+		pr_warn("map '%s': failed to alloc map name.\n", map_name);
+		return -ENOMEM;
+	}
+	map->libbpf_type = LIBBPF_MAP_UNSPEC;
+	map->def.type = BPF_MAP_TYPE_UNSPEC;
+	map->sec_idx = sec_idx;
+	map->sec_offset = vi->offset;
+	map->btf_var_idx = var_idx;
+	pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
+		 map_name, map->sec_idx, map->sec_offset);
+
+	err = parse_btf_map_def(map->name, obj->btf, def, strict, &map_def, &inner_def);
+	if (err)
+		return err;
+
+	fill_map_from_def(map, &map_def);
+
+	if (map_def.pinning == LIBBPF_PIN_BY_NAME) {
+		err = build_map_pin_path(map, pin_root_path);
+		if (err) {
+			pr_warn("map '%s': couldn't build pin path.\n", map->name);
+			return err;
+		}
+	}
+
+	if (map_def.parts & MAP_DEF_INNER_MAP) {
+		map->inner_map = calloc(1, sizeof(*map->inner_map));
+		if (!map->inner_map)
+			return -ENOMEM;
+		map->inner_map->fd = -1;
+		map->inner_map->sec_idx = sec_idx;
+		map->inner_map->name = malloc(strlen(map_name) + sizeof(".inner") + 1);
+		if (!map->inner_map->name)
+			return -ENOMEM;
+		sprintf(map->inner_map->name, "%s.inner", map_name);
+
+		fill_map_from_def(map->inner_map, &inner_def);
+	}
+
+	err = bpf_map_find_btf_info(obj, map);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
+					  const char *pin_root_path)
+{
+	const struct btf_type *sec = NULL;
+	int nr_types, i, vlen, err;
+	const struct btf_type *t;
+	const char *name;
+	Elf_Data *data;
+	Elf_Scn *scn;
+
+	if (obj->efile.btf_maps_shndx < 0)
+		return 0;
+
+	scn = elf_sec_by_idx(obj, obj->efile.btf_maps_shndx);
+	data = elf_sec_data(obj, scn);
+	if (!scn || !data) {
+		pr_warn("elf: failed to get %s map definitions for %s\n",
+			MAPS_ELF_SEC, obj->path);
+		return -EINVAL;
+	}
+
+	nr_types = btf__type_cnt(obj->btf);
+	for (i = 1; i < nr_types; i++) {
+		t = btf__type_by_id(obj->btf, i);
+		if (!btf_is_datasec(t))
+			continue;
+		name = btf__name_by_offset(obj->btf, t->name_off);
+		if (strcmp(name, MAPS_ELF_SEC) == 0) {
+			sec = t;
+			obj->efile.btf_maps_sec_btf_id = i;
+			break;
+		}
+	}
+
+	if (!sec) {
+		pr_warn("DATASEC '%s' not found.\n", MAPS_ELF_SEC);
+		return -ENOENT;
+	}
+
+	vlen = btf_vlen(sec);
+	for (i = 0; i < vlen; i++) {
+		err = bpf_object__init_user_btf_map(obj, sec, i,
+						    obj->efile.btf_maps_shndx,
+						    data, strict,
+						    pin_root_path);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int bpf_object__init_maps(struct bpf_object *obj,
+				 const struct bpf_object_open_opts *opts)
+{
+	const char *pin_root_path;
+	bool strict;
+	int err = 0;
+
+	strict = !OPTS_GET(opts, relaxed_maps, false);
+	pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
+
+	err = err ?: bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
+	err = err ?: bpf_object__init_global_data_maps(obj);
+	err = err ?: bpf_object__init_kconfig_map(obj);
+	err = err ?: bpf_object__init_struct_ops_maps(obj);
+
+	return err;
+}
+
+static bool section_have_execinstr(struct bpf_object *obj, int idx)
+{
+	Elf64_Shdr *sh;
+
+	sh = elf_sec_hdr(obj, elf_sec_by_idx(obj, idx));
+	if (!sh)
+		return false;
+
+	return sh->sh_flags & SHF_EXECINSTR;
+}
+
+static bool btf_needs_sanitization(struct bpf_object *obj)
+{
+	bool has_func_global = kernel_supports(obj, FEAT_BTF_GLOBAL_FUNC);
+	bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
+	bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
+	bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
+	bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
+	bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
+	bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64);
+
+	return !has_func || !has_datasec || !has_func_global || !has_float ||
+	       !has_decl_tag || !has_type_tag || !has_enum64;
+}
+
+static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
+{
+	bool has_func_global = kernel_supports(obj, FEAT_BTF_GLOBAL_FUNC);
+	bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
+	bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
+	bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
+	bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
+	bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
+	bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64);
+	int enum64_placeholder_id = 0;
+	struct btf_type *t;
+	int i, j, vlen;
+
+	for (i = 1; i < btf__type_cnt(btf); i++) {
+		t = (struct btf_type *)btf__type_by_id(btf, i);
+
+		if ((!has_datasec && btf_is_var(t)) || (!has_decl_tag && btf_is_decl_tag(t))) {
+			/* replace VAR/DECL_TAG with INT */
+			t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
+			/*
+			 * using size = 1 is the safest choice, 4 will be too
+			 * big and cause kernel BTF validation failure if
+			 * original variable took less than 4 bytes
+			 */
+			t->size = 1;
+			*(int *)(t + 1) = BTF_INT_ENC(0, 0, 8);
+		} else if (!has_datasec && btf_is_datasec(t)) {
+			/* replace DATASEC with STRUCT */
+			const struct btf_var_secinfo *v = btf_var_secinfos(t);
+			struct btf_member *m = btf_members(t);
+			struct btf_type *vt;
+			char *name;
+
+			name = (char *)btf__name_by_offset(btf, t->name_off);
+			while (*name) {
+				if (*name == '.')
+					*name = '_';
+				name++;
+			}
+
+			vlen = btf_vlen(t);
+			t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, vlen);
+			for (j = 0; j < vlen; j++, v++, m++) {
+				/* order of field assignments is important */
+				m->offset = v->offset * 8;
+				m->type = v->type;
+				/* preserve variable name as member name */
+				vt = (void *)btf__type_by_id(btf, v->type);
+				m->name_off = vt->name_off;
+			}
+		} else if (!has_func && btf_is_func_proto(t)) {
+			/* replace FUNC_PROTO with ENUM */
+			vlen = btf_vlen(t);
+			t->info = BTF_INFO_ENC(BTF_KIND_ENUM, 0, vlen);
+			t->size = sizeof(__u32); /* kernel enforced */
+		} else if (!has_func && btf_is_func(t)) {
+			/* replace FUNC with TYPEDEF */
+			t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0);
+		} else if (!has_func_global && btf_is_func(t)) {
+			/* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
+			t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
+		} else if (!has_float && btf_is_float(t)) {
+			/* replace FLOAT with an equally-sized empty STRUCT;
+			 * since C compilers do not accept e.g. "float" as a
+			 * valid struct name, make it anonymous
+			 */
+			t->name_off = 0;
+			t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0);
+		} else if (!has_type_tag && btf_is_type_tag(t)) {
+			/* replace TYPE_TAG with a CONST */
+			t->name_off = 0;
+			t->info = BTF_INFO_ENC(BTF_KIND_CONST, 0, 0);
+		} else if (!has_enum64 && btf_is_enum(t)) {
+			/* clear the kflag */
+			t->info = btf_type_info(btf_kind(t), btf_vlen(t), false);
+		} else if (!has_enum64 && btf_is_enum64(t)) {
+			/* replace ENUM64 with a union */
+			struct btf_member *m;
+
+			if (enum64_placeholder_id == 0) {
+				enum64_placeholder_id = btf__add_int(btf, "enum64_placeholder", 1, 0);
+				if (enum64_placeholder_id < 0)
+					return enum64_placeholder_id;
+
+				t = (struct btf_type *)btf__type_by_id(btf, i);
+			}
+
+			m = btf_members(t);
+			vlen = btf_vlen(t);
+			t->info = BTF_INFO_ENC(BTF_KIND_UNION, 0, vlen);
+			for (j = 0; j < vlen; j++, m++) {
+				m->type = enum64_placeholder_id;
+				m->offset = 0;
+			}
+                }
+	}
+
+	return 0;
+}
+
+static bool libbpf_needs_btf(const struct bpf_object *obj)
+{
+	return obj->efile.btf_maps_shndx >= 0 ||
+	       obj->efile.st_ops_shndx >= 0 ||
+	       obj->nr_extern > 0;
+}
+
+static bool kernel_needs_btf(const struct bpf_object *obj)
+{
+	return obj->efile.st_ops_shndx >= 0;
+}
+
+static int bpf_object__init_btf(struct bpf_object *obj,
+				Elf_Data *btf_data,
+				Elf_Data *btf_ext_data)
+{
+	int err = -ENOENT;
+
+	if (btf_data) {
+		obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
+		err = libbpf_get_error(obj->btf);
+		if (err) {
+			obj->btf = NULL;
+			pr_warn("Error loading ELF section %s: %d.\n", BTF_ELF_SEC, err);
+			goto out;
+		}
+		/* enforce 8-byte pointers for BPF-targeted BTFs */
+		btf__set_pointer_size(obj->btf, 8);
+	}
+	if (btf_ext_data) {
+		struct btf_ext_info *ext_segs[3];
+		int seg_num, sec_num;
+
+		if (!obj->btf) {
+			pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
+				 BTF_EXT_ELF_SEC, BTF_ELF_SEC);
+			goto out;
+		}
+		obj->btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
+		err = libbpf_get_error(obj->btf_ext);
+		if (err) {
+			pr_warn("Error loading ELF section %s: %d. Ignored and continue.\n",
+				BTF_EXT_ELF_SEC, err);
+			obj->btf_ext = NULL;
+			goto out;
+		}
+
+		/* setup .BTF.ext to ELF section mapping */
+		ext_segs[0] = &obj->btf_ext->func_info;
+		ext_segs[1] = &obj->btf_ext->line_info;
+		ext_segs[2] = &obj->btf_ext->core_relo_info;
+		for (seg_num = 0; seg_num < ARRAY_SIZE(ext_segs); seg_num++) {
+			struct btf_ext_info *seg = ext_segs[seg_num];
+			const struct btf_ext_info_sec *sec;
+			const char *sec_name;
+			Elf_Scn *scn;
+
+			if (seg->sec_cnt == 0)
+				continue;
+
+			seg->sec_idxs = calloc(seg->sec_cnt, sizeof(*seg->sec_idxs));
+			if (!seg->sec_idxs) {
+				err = -ENOMEM;
+				goto out;
+			}
+
+			sec_num = 0;
+			for_each_btf_ext_sec(seg, sec) {
+				/* preventively increment index to avoid doing
+				 * this before every continue below
+				 */
+				sec_num++;
+
+				sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
+				if (str_is_empty(sec_name))
+					continue;
+				scn = elf_sec_by_name(obj, sec_name);
+				if (!scn)
+					continue;
+
+				seg->sec_idxs[sec_num - 1] = elf_ndxscn(scn);
+			}
+		}
+	}
+out:
+	if (err && libbpf_needs_btf(obj)) {
+		pr_warn("BTF is required, but is missing or corrupted.\n");
+		return err;
+	}
+	return 0;
+}
+
+static int compare_vsi_off(const void *_a, const void *_b)
+{
+	const struct btf_var_secinfo *a = _a;
+	const struct btf_var_secinfo *b = _b;
+
+	return a->offset - b->offset;
+}
+
+static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
+			     struct btf_type *t)
+{
+	__u32 size = 0, off = 0, i, vars = btf_vlen(t);
+	const char *name = btf__name_by_offset(btf, t->name_off);
+	const struct btf_type *t_var;
+	struct btf_var_secinfo *vsi;
+	const struct btf_var *var;
+	int ret;
+
+	if (!name) {
+		pr_debug("No name found in string section for DATASEC kind.\n");
+		return -ENOENT;
+	}
+
+	/* .extern datasec size and var offsets were set correctly during
+	 * extern collection step, so just skip straight to sorting variables
+	 */
+	if (t->size)
+		goto sort_vars;
+
+	ret = find_elf_sec_sz(obj, name, &size);
+	if (ret || !size) {
+		pr_debug("Invalid size for section %s: %u bytes\n", name, size);
+		return -ENOENT;
+	}
+
+	t->size = size;
+
+	for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
+		t_var = btf__type_by_id(btf, vsi->type);
+		if (!t_var || !btf_is_var(t_var)) {
+			pr_debug("Non-VAR type seen in section %s\n", name);
+			return -EINVAL;
+		}
+
+		var = btf_var(t_var);
+		if (var->linkage == BTF_VAR_STATIC)
+			continue;
+
+		name = btf__name_by_offset(btf, t_var->name_off);
+		if (!name) {
+			pr_debug("No name found in string section for VAR kind\n");
+			return -ENOENT;
+		}
+
+		ret = find_elf_var_offset(obj, name, &off);
+		if (ret) {
+			pr_debug("No offset found in symbol table for VAR %s\n",
+				 name);
+			return -ENOENT;
+		}
+
+		vsi->offset = off;
+	}
+
+sort_vars:
+	qsort(btf_var_secinfos(t), vars, sizeof(*vsi), compare_vsi_off);
+	return 0;
+}
+
+static int btf_finalize_data(struct bpf_object *obj, struct btf *btf)
+{
+	int err = 0;
+	__u32 i, n = btf__type_cnt(btf);
+
+	for (i = 1; i < n; i++) {
+		struct btf_type *t = btf_type_by_id(btf, i);
+
+		/* Loader needs to fix up some of the things compiler
+		 * couldn't get its hands on while emitting BTF. This
+		 * is section size and global variable offset. We use
+		 * the info from the ELF itself for this purpose.
+		 */
+		if (btf_is_datasec(t)) {
+			err = btf_fixup_datasec(obj, btf, t);
+			if (err)
+				break;
+		}
+	}
+
+	return libbpf_err(err);
+}
+
+static int bpf_object__finalize_btf(struct bpf_object *obj)
+{
+	int err;
+
+	if (!obj->btf)
+		return 0;
+
+	err = btf_finalize_data(obj, obj->btf);
+	if (err) {
+		pr_warn("Error finalizing %s: %d.\n", BTF_ELF_SEC, err);
+		return err;
+	}
+
+	return 0;
+}
+
+static bool prog_needs_vmlinux_btf(struct bpf_program *prog)
+{
+	if (prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
+	    prog->type == BPF_PROG_TYPE_LSM)
+		return true;
+
+	/* BPF_PROG_TYPE_TRACING programs which do not attach to other programs
+	 * also need vmlinux BTF
+	 */
+	if (prog->type == BPF_PROG_TYPE_TRACING && !prog->attach_prog_fd)
+		return true;
+
+	return false;
+}
+
+static bool obj_needs_vmlinux_btf(const struct bpf_object *obj)
+{
+	struct bpf_program *prog;
+	int i;
+
+	/* CO-RE relocations need kernel BTF, only when btf_custom_path
+	 * is not specified
+	 */
+	if (obj->btf_ext && obj->btf_ext->core_relo_info.len && !obj->btf_custom_path)
+		return true;
+
+	/* Support for typed ksyms needs kernel BTF */
+	for (i = 0; i < obj->nr_extern; i++) {
+		const struct extern_desc *ext;
+
+		ext = &obj->externs[i];
+		if (ext->type == EXT_KSYM && ext->ksym.type_id)
+			return true;
+	}
+
+	bpf_object__for_each_program(prog, obj) {
+		if (!prog->autoload)
+			continue;
+		if (prog_needs_vmlinux_btf(prog))
+			return true;
+	}
+
+	return false;
+}
+
+static int bpf_object__load_vmlinux_btf(struct bpf_object *obj, bool force)
+{
+	int err;
+
+	/* btf_vmlinux could be loaded earlier */
+	if (obj->btf_vmlinux || obj->gen_loader)
+		return 0;
+
+	if (!force && !obj_needs_vmlinux_btf(obj))
+		return 0;
+
+	obj->btf_vmlinux = btf__load_vmlinux_btf();
+	err = libbpf_get_error(obj->btf_vmlinux);
+	if (err) {
+		pr_warn("Error loading vmlinux BTF: %d\n", err);
+		obj->btf_vmlinux = NULL;
+		return err;
+	}
+	return 0;
+}
+
+static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
+{
+	struct btf *kern_btf = obj->btf;
+	bool btf_mandatory, sanitize;
+	int i, err = 0;
+
+	if (!obj->btf)
+		return 0;
+
+	if (!kernel_supports(obj, FEAT_BTF)) {
+		if (kernel_needs_btf(obj)) {
+			err = -EOPNOTSUPP;
+			goto report;
+		}
+		pr_debug("Kernel doesn't support BTF, skipping uploading it.\n");
+		return 0;
+	}
+
+	/* Even though some subprogs are global/weak, user might prefer more
+	 * permissive BPF verification process that BPF verifier performs for
+	 * static functions, taking into account more context from the caller
+	 * functions. In such case, they need to mark such subprogs with
+	 * __attribute__((visibility("hidden"))) and libbpf will adjust
+	 * corresponding FUNC BTF type to be marked as static and trigger more
+	 * involved BPF verification process.
+	 */
+	for (i = 0; i < obj->nr_programs; i++) {
+		struct bpf_program *prog = &obj->programs[i];
+		struct btf_type *t;
+		const char *name;
+		int j, n;
+
+		if (!prog->mark_btf_static || !prog_is_subprog(obj, prog))
+			continue;
+
+		n = btf__type_cnt(obj->btf);
+		for (j = 1; j < n; j++) {
+			t = btf_type_by_id(obj->btf, j);
+			if (!btf_is_func(t) || btf_func_linkage(t) != BTF_FUNC_GLOBAL)
+				continue;
+
+			name = btf__str_by_offset(obj->btf, t->name_off);
+			if (strcmp(name, prog->name) != 0)
+				continue;
+
+			t->info = btf_type_info(BTF_KIND_FUNC, BTF_FUNC_STATIC, 0);
+			break;
+		}
+	}
+
+	sanitize = btf_needs_sanitization(obj);
+	if (sanitize) {
+		const void *raw_data;
+		__u32 sz;
+
+		/* clone BTF to sanitize a copy and leave the original intact */
+		raw_data = btf__raw_data(obj->btf, &sz);
+		kern_btf = btf__new(raw_data, sz);
+		err = libbpf_get_error(kern_btf);
+		if (err)
+			return err;
+
+		/* enforce 8-byte pointers for BPF-targeted BTFs */
+		btf__set_pointer_size(obj->btf, 8);
+		err = bpf_object__sanitize_btf(obj, kern_btf);
+		if (err)
+			return err;
+	}
+
+	if (obj->gen_loader) {
+		__u32 raw_size = 0;
+		const void *raw_data = btf__raw_data(kern_btf, &raw_size);
+
+		if (!raw_data)
+			return -ENOMEM;
+		bpf_gen__load_btf(obj->gen_loader, raw_data, raw_size);
+		/* Pretend to have valid FD to pass various fd >= 0 checks.
+		 * This fd == 0 will not be used with any syscall and will be reset to -1 eventually.
+		 */
+		btf__set_fd(kern_btf, 0);
+	} else {
+		/* currently BPF_BTF_LOAD only supports log_level 1 */
+		err = btf_load_into_kernel(kern_btf, obj->log_buf, obj->log_size,
+					   obj->log_level ? 1 : 0);
+	}
+	if (sanitize) {
+		if (!err) {
+			/* move fd to libbpf's BTF */
+			btf__set_fd(obj->btf, btf__fd(kern_btf));
+			btf__set_fd(kern_btf, -1);
+		}
+		btf__free(kern_btf);
+	}
+report:
+	if (err) {
+		btf_mandatory = kernel_needs_btf(obj);
+		pr_warn("Error loading .BTF into kernel: %d. %s\n", err,
+			btf_mandatory ? "BTF is mandatory, can't proceed."
+				      : "BTF is optional, ignoring.");
+		if (!btf_mandatory)
+			err = 0;
+	}
+	return err;
+}
+
+static const char *elf_sym_str(const struct bpf_object *obj, size_t off)
+{
+	const char *name;
+
+	name = elf_strptr(obj->efile.elf, obj->efile.strtabidx, off);
+	if (!name) {
+		pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
+			off, obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+
+	return name;
+}
+
+static const char *elf_sec_str(const struct bpf_object *obj, size_t off)
+{
+	const char *name;
+
+	name = elf_strptr(obj->efile.elf, obj->efile.shstrndx, off);
+	if (!name) {
+		pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
+			off, obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+
+	return name;
+}
+
+static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx)
+{
+	Elf_Scn *scn;
+
+	scn = elf_getscn(obj->efile.elf, idx);
+	if (!scn) {
+		pr_warn("elf: failed to get section(%zu) from %s: %s\n",
+			idx, obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+	return scn;
+}
+
+static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name)
+{
+	Elf_Scn *scn = NULL;
+	Elf *elf = obj->efile.elf;
+	const char *sec_name;
+
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		sec_name = elf_sec_name(obj, scn);
+		if (!sec_name)
+			return NULL;
+
+		if (strcmp(sec_name, name) != 0)
+			continue;
+
+		return scn;
+	}
+	return NULL;
+}
+
+static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn)
+{
+	Elf64_Shdr *shdr;
+
+	if (!scn)
+		return NULL;
+
+	shdr = elf64_getshdr(scn);
+	if (!shdr) {
+		pr_warn("elf: failed to get section(%zu) header from %s: %s\n",
+			elf_ndxscn(scn), obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+
+	return shdr;
+}
+
+static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn)
+{
+	const char *name;
+	Elf64_Shdr *sh;
+
+	if (!scn)
+		return NULL;
+
+	sh = elf_sec_hdr(obj, scn);
+	if (!sh)
+		return NULL;
+
+	name = elf_sec_str(obj, sh->sh_name);
+	if (!name) {
+		pr_warn("elf: failed to get section(%zu) name from %s: %s\n",
+			elf_ndxscn(scn), obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+
+	return name;
+}
+
+static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn)
+{
+	Elf_Data *data;
+
+	if (!scn)
+		return NULL;
+
+	data = elf_getdata(scn, 0);
+	if (!data) {
+		pr_warn("elf: failed to get section(%zu) %s data from %s: %s\n",
+			elf_ndxscn(scn), elf_sec_name(obj, scn) ?: "<?>",
+			obj->path, elf_errmsg(-1));
+		return NULL;
+	}
+
+	return data;
+}
+
+static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx)
+{
+	if (idx >= obj->efile.symbols->d_size / sizeof(Elf64_Sym))
+		return NULL;
+
+	return (Elf64_Sym *)obj->efile.symbols->d_buf + idx;
+}
+
+static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx)
+{
+	if (idx >= data->d_size / sizeof(Elf64_Rel))
+		return NULL;
+
+	return (Elf64_Rel *)data->d_buf + idx;
+}
+
+static bool is_sec_name_dwarf(const char *name)
+{
+	/* approximation, but the actual list is too long */
+	return str_has_pfx(name, ".debug_");
+}
+
+static bool ignore_elf_section(Elf64_Shdr *hdr, const char *name)
+{
+	/* no special handling of .strtab */
+	if (hdr->sh_type == SHT_STRTAB)
+		return true;
+
+	/* ignore .llvm_addrsig section as well */
+	if (hdr->sh_type == SHT_LLVM_ADDRSIG)
+		return true;
+
+	/* no subprograms will lead to an empty .text section, ignore it */
+	if (hdr->sh_type == SHT_PROGBITS && hdr->sh_size == 0 &&
+	    strcmp(name, ".text") == 0)
+		return true;
+
+	/* DWARF sections */
+	if (is_sec_name_dwarf(name))
+		return true;
+
+	if (str_has_pfx(name, ".rel")) {
+		name += sizeof(".rel") - 1;
+		/* DWARF section relocations */
+		if (is_sec_name_dwarf(name))
+			return true;
+
+		/* .BTF and .BTF.ext don't need relocations */
+		if (strcmp(name, BTF_ELF_SEC) == 0 ||
+		    strcmp(name, BTF_EXT_ELF_SEC) == 0)
+			return true;
+	}
+
+	return false;
+}
+
+static int cmp_progs(const void *_a, const void *_b)
+{
+	const struct bpf_program *a = _a;
+	const struct bpf_program *b = _b;
+
+	if (a->sec_idx != b->sec_idx)
+		return a->sec_idx < b->sec_idx ? -1 : 1;
+
+	/* sec_insn_off can't be the same within the section */
+	return a->sec_insn_off < b->sec_insn_off ? -1 : 1;
+}
+
+static int bpf_object__elf_collect(struct bpf_object *obj)
+{
+	struct elf_sec_desc *sec_desc;
+	Elf *elf = obj->efile.elf;
+	Elf_Data *btf_ext_data = NULL;
+	Elf_Data *btf_data = NULL;
+	int idx = 0, err = 0;
+	const char *name;
+	Elf_Data *data;
+	Elf_Scn *scn;
+	Elf64_Shdr *sh;
+
+	/* ELF section indices are 0-based, but sec #0 is special "invalid"
+	 * section. Since section count retrieved by elf_getshdrnum() does
+	 * include sec #0, it is already the necessary size of an array to keep
+	 * all the sections.
+	 */
+	if (elf_getshdrnum(obj->efile.elf, &obj->efile.sec_cnt)) {
+		pr_warn("elf: failed to get the number of sections for %s: %s\n",
+			obj->path, elf_errmsg(-1));
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	obj->efile.secs = calloc(obj->efile.sec_cnt, sizeof(*obj->efile.secs));
+	if (!obj->efile.secs)
+		return -ENOMEM;
+
+	/* a bunch of ELF parsing functionality depends on processing symbols,
+	 * so do the first pass and find the symbol table
+	 */
+	scn = NULL;
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		sh = elf_sec_hdr(obj, scn);
+		if (!sh)
+			return -LIBBPF_ERRNO__FORMAT;
+
+		if (sh->sh_type == SHT_SYMTAB) {
+			if (obj->efile.symbols) {
+				pr_warn("elf: multiple symbol tables in %s\n", obj->path);
+				return -LIBBPF_ERRNO__FORMAT;
+			}
+
+			data = elf_sec_data(obj, scn);
+			if (!data)
+				return -LIBBPF_ERRNO__FORMAT;
+
+			idx = elf_ndxscn(scn);
+
+			obj->efile.symbols = data;
+			obj->efile.symbols_shndx = idx;
+			obj->efile.strtabidx = sh->sh_link;
+		}
+	}
+
+	if (!obj->efile.symbols) {
+		pr_warn("elf: couldn't find symbol table in %s, stripped object file?\n",
+			obj->path);
+		return -ENOENT;
+	}
+
+	scn = NULL;
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		idx = elf_ndxscn(scn);
+		sec_desc = &obj->efile.secs[idx];
+
+		sh = elf_sec_hdr(obj, scn);
+		if (!sh)
+			return -LIBBPF_ERRNO__FORMAT;
+
+		name = elf_sec_str(obj, sh->sh_name);
+		if (!name)
+			return -LIBBPF_ERRNO__FORMAT;
+
+		if (ignore_elf_section(sh, name))
+			continue;
+
+		data = elf_sec_data(obj, scn);
+		if (!data)
+			return -LIBBPF_ERRNO__FORMAT;
+
+		pr_debug("elf: section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
+			 idx, name, (unsigned long)data->d_size,
+			 (int)sh->sh_link, (unsigned long)sh->sh_flags,
+			 (int)sh->sh_type);
+
+		if (strcmp(name, "license") == 0) {
+			err = bpf_object__init_license(obj, data->d_buf, data->d_size);
+			if (err)
+				return err;
+		} else if (strcmp(name, "version") == 0) {
+			err = bpf_object__init_kversion(obj, data->d_buf, data->d_size);
+			if (err)
+				return err;
+		} else if (strcmp(name, "maps") == 0) {
+			pr_warn("elf: legacy map definitions in 'maps' section are not supported by libbpf v1.0+\n");
+			return -ENOTSUP;
+		} else if (strcmp(name, MAPS_ELF_SEC) == 0) {
+			obj->efile.btf_maps_shndx = idx;
+		} else if (strcmp(name, BTF_ELF_SEC) == 0) {
+			if (sh->sh_type != SHT_PROGBITS)
+				return -LIBBPF_ERRNO__FORMAT;
+			btf_data = data;
+		} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
+			if (sh->sh_type != SHT_PROGBITS)
+				return -LIBBPF_ERRNO__FORMAT;
+			btf_ext_data = data;
+		} else if (sh->sh_type == SHT_SYMTAB) {
+			/* already processed during the first pass above */
+		} else if (sh->sh_type == SHT_PROGBITS && data->d_size > 0) {
+			if (sh->sh_flags & SHF_EXECINSTR) {
+				if (strcmp(name, ".text") == 0)
+					obj->efile.text_shndx = idx;
+				err = bpf_object__add_programs(obj, data, name, idx);
+				if (err)
+					return err;
+			} else if (strcmp(name, DATA_SEC) == 0 ||
+				   str_has_pfx(name, DATA_SEC ".")) {
+				sec_desc->sec_type = SEC_DATA;
+				sec_desc->shdr = sh;
+				sec_desc->data = data;
+			} else if (strcmp(name, RODATA_SEC) == 0 ||
+				   str_has_pfx(name, RODATA_SEC ".")) {
+				sec_desc->sec_type = SEC_RODATA;
+				sec_desc->shdr = sh;
+				sec_desc->data = data;
+			} else if (strcmp(name, STRUCT_OPS_SEC) == 0) {
+				obj->efile.st_ops_data = data;
+				obj->efile.st_ops_shndx = idx;
+			} else {
+				pr_info("elf: skipping unrecognized data section(%d) %s\n",
+					idx, name);
+			}
+		} else if (sh->sh_type == SHT_REL) {
+			int targ_sec_idx = sh->sh_info; /* points to other section */
+
+			if (sh->sh_entsize != sizeof(Elf64_Rel) ||
+			    targ_sec_idx >= obj->efile.sec_cnt)
+				return -LIBBPF_ERRNO__FORMAT;
+
+			/* Only do relo for section with exec instructions */
+			if (!section_have_execinstr(obj, targ_sec_idx) &&
+			    strcmp(name, ".rel" STRUCT_OPS_SEC) &&
+			    strcmp(name, ".rel" MAPS_ELF_SEC)) {
+				pr_info("elf: skipping relo section(%d) %s for section(%d) %s\n",
+					idx, name, targ_sec_idx,
+					elf_sec_name(obj, elf_sec_by_idx(obj, targ_sec_idx)) ?: "<?>");
+				continue;
+			}
+
+			sec_desc->sec_type = SEC_RELO;
+			sec_desc->shdr = sh;
+			sec_desc->data = data;
+		} else if (sh->sh_type == SHT_NOBITS && strcmp(name, BSS_SEC) == 0) {
+			sec_desc->sec_type = SEC_BSS;
+			sec_desc->shdr = sh;
+			sec_desc->data = data;
+		} else {
+			pr_info("elf: skipping section(%d) %s (size %zu)\n", idx, name,
+				(size_t)sh->sh_size);
+		}
+	}
+
+	if (!obj->efile.strtabidx || obj->efile.strtabidx > idx) {
+		pr_warn("elf: symbol strings section missing or invalid in %s\n", obj->path);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+
+	/* sort BPF programs by section name and in-section instruction offset
+	 * for faster search */
+	if (obj->nr_programs)
+		qsort(obj->programs, obj->nr_programs, sizeof(*obj->programs), cmp_progs);
+
+	return bpf_object__init_btf(obj, btf_data, btf_ext_data);
+}
+
+static bool sym_is_extern(const Elf64_Sym *sym)
+{
+	int bind = ELF64_ST_BIND(sym->st_info);
+	/* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */
+	return sym->st_shndx == SHN_UNDEF &&
+	       (bind == STB_GLOBAL || bind == STB_WEAK) &&
+	       ELF64_ST_TYPE(sym->st_info) == STT_NOTYPE;
+}
+
+static bool sym_is_subprog(const Elf64_Sym *sym, int text_shndx)
+{
+	int bind = ELF64_ST_BIND(sym->st_info);
+	int type = ELF64_ST_TYPE(sym->st_info);
+
+	/* in .text section */
+	if (sym->st_shndx != text_shndx)
+		return false;
+
+	/* local function */
+	if (bind == STB_LOCAL && type == STT_SECTION)
+		return true;
+
+	/* global function */
+	return bind == STB_GLOBAL && type == STT_FUNC;
+}
+
+static int find_extern_btf_id(const struct btf *btf, const char *ext_name)
+{
+	const struct btf_type *t;
+	const char *tname;
+	int i, n;
+
+	if (!btf)
+		return -ESRCH;
+
+	n = btf__type_cnt(btf);
+	for (i = 1; i < n; i++) {
+		t = btf__type_by_id(btf, i);
+
+		if (!btf_is_var(t) && !btf_is_func(t))
+			continue;
+
+		tname = btf__name_by_offset(btf, t->name_off);
+		if (strcmp(tname, ext_name))
+			continue;
+
+		if (btf_is_var(t) &&
+		    btf_var(t)->linkage != BTF_VAR_GLOBAL_EXTERN)
+			return -EINVAL;
+
+		if (btf_is_func(t) && btf_func_linkage(t) != BTF_FUNC_EXTERN)
+			return -EINVAL;
+
+		return i;
+	}
+
+	return -ENOENT;
+}
+
+static int find_extern_sec_btf_id(struct btf *btf, int ext_btf_id) {
+	const struct btf_var_secinfo *vs;
+	const struct btf_type *t;
+	int i, j, n;
+
+	if (!btf)
+		return -ESRCH;
+
+	n = btf__type_cnt(btf);
+	for (i = 1; i < n; i++) {
+		t = btf__type_by_id(btf, i);
+
+		if (!btf_is_datasec(t))
+			continue;
+
+		vs = btf_var_secinfos(t);
+		for (j = 0; j < btf_vlen(t); j++, vs++) {
+			if (vs->type == ext_btf_id)
+				return i;
+		}
+	}
+
+	return -ENOENT;
+}
+
+static enum kcfg_type find_kcfg_type(const struct btf *btf, int id,
+				     bool *is_signed)
+{
+	const struct btf_type *t;
+	const char *name;
+
+	t = skip_mods_and_typedefs(btf, id, NULL);
+	name = btf__name_by_offset(btf, t->name_off);
+
+	if (is_signed)
+		*is_signed = false;
+	switch (btf_kind(t)) {
+	case BTF_KIND_INT: {
+		int enc = btf_int_encoding(t);
+
+		if (enc & BTF_INT_BOOL)
+			return t->size == 1 ? KCFG_BOOL : KCFG_UNKNOWN;
+		if (is_signed)
+			*is_signed = enc & BTF_INT_SIGNED;
+		if (t->size == 1)
+			return KCFG_CHAR;
+		if (t->size < 1 || t->size > 8 || (t->size & (t->size - 1)))
+			return KCFG_UNKNOWN;
+		return KCFG_INT;
+	}
+	case BTF_KIND_ENUM:
+		if (t->size != 4)
+			return KCFG_UNKNOWN;
+		if (strcmp(name, "libbpf_tristate"))
+			return KCFG_UNKNOWN;
+		return KCFG_TRISTATE;
+	case BTF_KIND_ENUM64:
+		if (strcmp(name, "libbpf_tristate"))
+			return KCFG_UNKNOWN;
+		return KCFG_TRISTATE;
+	case BTF_KIND_ARRAY:
+		if (btf_array(t)->nelems == 0)
+			return KCFG_UNKNOWN;
+		if (find_kcfg_type(btf, btf_array(t)->type, NULL) != KCFG_CHAR)
+			return KCFG_UNKNOWN;
+		return KCFG_CHAR_ARR;
+	default:
+		return KCFG_UNKNOWN;
+	}
+}
+
+static int cmp_externs(const void *_a, const void *_b)
+{
+	const struct extern_desc *a = _a;
+	const struct extern_desc *b = _b;
+
+	if (a->type != b->type)
+		return a->type < b->type ? -1 : 1;
+
+	if (a->type == EXT_KCFG) {
+		/* descending order by alignment requirements */
+		if (a->kcfg.align != b->kcfg.align)
+			return a->kcfg.align > b->kcfg.align ? -1 : 1;
+		/* ascending order by size, within same alignment class */
+		if (a->kcfg.sz != b->kcfg.sz)
+			return a->kcfg.sz < b->kcfg.sz ? -1 : 1;
+	}
+
+	/* resolve ties by name */
+	return strcmp(a->name, b->name);
+}
+
+static int find_int_btf_id(const struct btf *btf)
+{
+	const struct btf_type *t;
+	int i, n;
+
+	n = btf__type_cnt(btf);
+	for (i = 1; i < n; i++) {
+		t = btf__type_by_id(btf, i);
+
+		if (btf_is_int(t) && btf_int_bits(t) == 32)
+			return i;
+	}
+
+	return 0;
+}
+
+static int add_dummy_ksym_var(struct btf *btf)
+{
+	int i, int_btf_id, sec_btf_id, dummy_var_btf_id;
+	const struct btf_var_secinfo *vs;
+	const struct btf_type *sec;
+
+	if (!btf)
+		return 0;
+
+	sec_btf_id = btf__find_by_name_kind(btf, KSYMS_SEC,
+					    BTF_KIND_DATASEC);
+	if (sec_btf_id < 0)
+		return 0;
+
+	sec = btf__type_by_id(btf, sec_btf_id);
+	vs = btf_var_secinfos(sec);
+	for (i = 0; i < btf_vlen(sec); i++, vs++) {
+		const struct btf_type *vt;
+
+		vt = btf__type_by_id(btf, vs->type);
+		if (btf_is_func(vt))
+			break;
+	}
+
+	/* No func in ksyms sec.  No need to add dummy var. */
+	if (i == btf_vlen(sec))
+		return 0;
+
+	int_btf_id = find_int_btf_id(btf);
+	dummy_var_btf_id = btf__add_var(btf,
+					"dummy_ksym",
+					BTF_VAR_GLOBAL_ALLOCATED,
+					int_btf_id);
+	if (dummy_var_btf_id < 0)
+		pr_warn("cannot create a dummy_ksym var\n");
+
+	return dummy_var_btf_id;
+}
+
+static int bpf_object__collect_externs(struct bpf_object *obj)
+{
+	struct btf_type *sec, *kcfg_sec = NULL, *ksym_sec = NULL;
+	const struct btf_type *t;
+	struct extern_desc *ext;
+	int i, n, off, dummy_var_btf_id;
+	const char *ext_name, *sec_name;
+	Elf_Scn *scn;
+	Elf64_Shdr *sh;
+
+	if (!obj->efile.symbols)
+		return 0;
+
+	scn = elf_sec_by_idx(obj, obj->efile.symbols_shndx);
+	sh = elf_sec_hdr(obj, scn);
+	if (!sh || sh->sh_entsize != sizeof(Elf64_Sym))
+		return -LIBBPF_ERRNO__FORMAT;
+
+	dummy_var_btf_id = add_dummy_ksym_var(obj->btf);
+	if (dummy_var_btf_id < 0)
+		return dummy_var_btf_id;
+
+	n = sh->sh_size / sh->sh_entsize;
+	pr_debug("looking for externs among %d symbols...\n", n);
+
+	for (i = 0; i < n; i++) {
+		Elf64_Sym *sym = elf_sym_by_idx(obj, i);
+
+		if (!sym)
+			return -LIBBPF_ERRNO__FORMAT;
+		if (!sym_is_extern(sym))
+			continue;
+		ext_name = elf_sym_str(obj, sym->st_name);
+		if (!ext_name || !ext_name[0])
+			continue;
+
+		ext = obj->externs;
+		ext = libbpf_reallocarray(ext, obj->nr_extern + 1, sizeof(*ext));
+		if (!ext)
+			return -ENOMEM;
+		obj->externs = ext;
+		ext = &ext[obj->nr_extern];
+		memset(ext, 0, sizeof(*ext));
+		obj->nr_extern++;
+
+		ext->btf_id = find_extern_btf_id(obj->btf, ext_name);
+		if (ext->btf_id <= 0) {
+			pr_warn("failed to find BTF for extern '%s': %d\n",
+				ext_name, ext->btf_id);
+			return ext->btf_id;
+		}
+		t = btf__type_by_id(obj->btf, ext->btf_id);
+		ext->name = btf__name_by_offset(obj->btf, t->name_off);
+		ext->sym_idx = i;
+		ext->is_weak = ELF64_ST_BIND(sym->st_info) == STB_WEAK;
+
+		ext->sec_btf_id = find_extern_sec_btf_id(obj->btf, ext->btf_id);
+		if (ext->sec_btf_id <= 0) {
+			pr_warn("failed to find BTF for extern '%s' [%d] section: %d\n",
+				ext_name, ext->btf_id, ext->sec_btf_id);
+			return ext->sec_btf_id;
+		}
+		sec = (void *)btf__type_by_id(obj->btf, ext->sec_btf_id);
+		sec_name = btf__name_by_offset(obj->btf, sec->name_off);
+
+		if (strcmp(sec_name, KCONFIG_SEC) == 0) {
+			if (btf_is_func(t)) {
+				pr_warn("extern function %s is unsupported under %s section\n",
+					ext->name, KCONFIG_SEC);
+				return -ENOTSUP;
+			}
+			kcfg_sec = sec;
+			ext->type = EXT_KCFG;
+			ext->kcfg.sz = btf__resolve_size(obj->btf, t->type);
+			if (ext->kcfg.sz <= 0) {
+				pr_warn("failed to resolve size of extern (kcfg) '%s': %d\n",
+					ext_name, ext->kcfg.sz);
+				return ext->kcfg.sz;
+			}
+			ext->kcfg.align = btf__align_of(obj->btf, t->type);
+			if (ext->kcfg.align <= 0) {
+				pr_warn("failed to determine alignment of extern (kcfg) '%s': %d\n",
+					ext_name, ext->kcfg.align);
+				return -EINVAL;
+			}
+			ext->kcfg.type = find_kcfg_type(obj->btf, t->type,
+						        &ext->kcfg.is_signed);
+			if (ext->kcfg.type == KCFG_UNKNOWN) {
+				pr_warn("extern (kcfg) '%s': type is unsupported\n", ext_name);
+				return -ENOTSUP;
+			}
+		} else if (strcmp(sec_name, KSYMS_SEC) == 0) {
+			ksym_sec = sec;
+			ext->type = EXT_KSYM;
+			skip_mods_and_typedefs(obj->btf, t->type,
+					       &ext->ksym.type_id);
+		} else {
+			pr_warn("unrecognized extern section '%s'\n", sec_name);
+			return -ENOTSUP;
+		}
+	}
+	pr_debug("collected %d externs total\n", obj->nr_extern);
+
+	if (!obj->nr_extern)
+		return 0;
+
+	/* sort externs by type, for kcfg ones also by (align, size, name) */
+	qsort(obj->externs, obj->nr_extern, sizeof(*ext), cmp_externs);
+
+	/* for .ksyms section, we need to turn all externs into allocated
+	 * variables in BTF to pass kernel verification; we do this by
+	 * pretending that each extern is a 8-byte variable
+	 */
+	if (ksym_sec) {
+		/* find existing 4-byte integer type in BTF to use for fake
+		 * extern variables in DATASEC
+		 */
+		int int_btf_id = find_int_btf_id(obj->btf);
+		/* For extern function, a dummy_var added earlier
+		 * will be used to replace the vs->type and
+		 * its name string will be used to refill
+		 * the missing param's name.
+		 */
+		const struct btf_type *dummy_var;
+
+		dummy_var = btf__type_by_id(obj->btf, dummy_var_btf_id);
+		for (i = 0; i < obj->nr_extern; i++) {
+			ext = &obj->externs[i];
+			if (ext->type != EXT_KSYM)
+				continue;
+			pr_debug("extern (ksym) #%d: symbol %d, name %s\n",
+				 i, ext->sym_idx, ext->name);
+		}
+
+		sec = ksym_sec;
+		n = btf_vlen(sec);
+		for (i = 0, off = 0; i < n; i++, off += sizeof(int)) {
+			struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
+			struct btf_type *vt;
+
+			vt = (void *)btf__type_by_id(obj->btf, vs->type);
+			ext_name = btf__name_by_offset(obj->btf, vt->name_off);
+			ext = find_extern_by_name(obj, ext_name);
+			if (!ext) {
+				pr_warn("failed to find extern definition for BTF %s '%s'\n",
+					btf_kind_str(vt), ext_name);
+				return -ESRCH;
+			}
+			if (btf_is_func(vt)) {
+				const struct btf_type *func_proto;
+				struct btf_param *param;
+				int j;
+
+				func_proto = btf__type_by_id(obj->btf,
+							     vt->type);
+				param = btf_params(func_proto);
+				/* Reuse the dummy_var string if the
+				 * func proto does not have param name.
+				 */
+				for (j = 0; j < btf_vlen(func_proto); j++)
+					if (param[j].type && !param[j].name_off)
+						param[j].name_off =
+							dummy_var->name_off;
+				vs->type = dummy_var_btf_id;
+				vt->info &= ~0xffff;
+				vt->info |= BTF_FUNC_GLOBAL;
+			} else {
+				btf_var(vt)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
+				vt->type = int_btf_id;
+			}
+			vs->offset = off;
+			vs->size = sizeof(int);
+		}
+		sec->size = off;
+	}
+
+	if (kcfg_sec) {
+		sec = kcfg_sec;
+		/* for kcfg externs calculate their offsets within a .kconfig map */
+		off = 0;
+		for (i = 0; i < obj->nr_extern; i++) {
+			ext = &obj->externs[i];
+			if (ext->type != EXT_KCFG)
+				continue;
+
+			ext->kcfg.data_off = roundup(off, ext->kcfg.align);
+			off = ext->kcfg.data_off + ext->kcfg.sz;
+			pr_debug("extern (kcfg) #%d: symbol %d, off %u, name %s\n",
+				 i, ext->sym_idx, ext->kcfg.data_off, ext->name);
+		}
+		sec->size = off;
+		n = btf_vlen(sec);
+		for (i = 0; i < n; i++) {
+			struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
+
+			t = btf__type_by_id(obj->btf, vs->type);
+			ext_name = btf__name_by_offset(obj->btf, t->name_off);
+			ext = find_extern_by_name(obj, ext_name);
+			if (!ext) {
+				pr_warn("failed to find extern definition for BTF var '%s'\n",
+					ext_name);
+				return -ESRCH;
+			}
+			btf_var(t)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
+			vs->offset = ext->kcfg.data_off;
+		}
+	}
+	return 0;
+}
+
+static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog)
+{
+	return prog->sec_idx == obj->efile.text_shndx && obj->nr_programs > 1;
+}
+
+struct bpf_program *
+bpf_object__find_program_by_name(const struct bpf_object *obj,
+				 const char *name)
+{
+	struct bpf_program *prog;
+
+	bpf_object__for_each_program(prog, obj) {
+		if (prog_is_subprog(obj, prog))
+			continue;
+		if (!strcmp(prog->name, name))
+			return prog;
+	}
+	return errno = ENOENT, NULL;
+}
+
+static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
+				      int shndx)
+{
+	switch (obj->efile.secs[shndx].sec_type) {
+	case SEC_BSS:
+	case SEC_DATA:
+	case SEC_RODATA:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
+				      int shndx)
+{
+	return shndx == obj->efile.btf_maps_shndx;
+}
+
+static enum libbpf_map_type
+bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
+{
+	if (shndx == obj->efile.symbols_shndx)
+		return LIBBPF_MAP_KCONFIG;
+
+	switch (obj->efile.secs[shndx].sec_type) {
+	case SEC_BSS:
+		return LIBBPF_MAP_BSS;
+	case SEC_DATA:
+		return LIBBPF_MAP_DATA;
+	case SEC_RODATA:
+		return LIBBPF_MAP_RODATA;
+	default:
+		return LIBBPF_MAP_UNSPEC;
+	}
+}
+
+static int bpf_program__record_reloc(struct bpf_program *prog,
+				     struct reloc_desc *reloc_desc,
+				     __u32 insn_idx, const char *sym_name,
+				     const Elf64_Sym *sym, const Elf64_Rel *rel)
+{
+	struct bpf_insn *insn = &prog->insns[insn_idx];
+	size_t map_idx, nr_maps = prog->obj->nr_maps;
+	struct bpf_object *obj = prog->obj;
+	__u32 shdr_idx = sym->st_shndx;
+	enum libbpf_map_type type;
+	const char *sym_sec_name;
+	struct bpf_map *map;
+
+	if (!is_call_insn(insn) && !is_ldimm64_insn(insn)) {
+		pr_warn("prog '%s': invalid relo against '%s' for insns[%d].code 0x%x\n",
+			prog->name, sym_name, insn_idx, insn->code);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+
+	if (sym_is_extern(sym)) {
+		int sym_idx = ELF64_R_SYM(rel->r_info);
+		int i, n = obj->nr_extern;
+		struct extern_desc *ext;
+
+		for (i = 0; i < n; i++) {
+			ext = &obj->externs[i];
+			if (ext->sym_idx == sym_idx)
+				break;
+		}
+		if (i >= n) {
+			pr_warn("prog '%s': extern relo failed to find extern for '%s' (%d)\n",
+				prog->name, sym_name, sym_idx);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		pr_debug("prog '%s': found extern #%d '%s' (sym %d) for insn #%u\n",
+			 prog->name, i, ext->name, ext->sym_idx, insn_idx);
+		if (insn->code == (BPF_JMP | BPF_CALL))
+			reloc_desc->type = RELO_EXTERN_FUNC;
+		else
+			reloc_desc->type = RELO_EXTERN_VAR;
+		reloc_desc->insn_idx = insn_idx;
+		reloc_desc->sym_off = i; /* sym_off stores extern index */
+		return 0;
+	}
+
+	/* sub-program call relocation */
+	if (is_call_insn(insn)) {
+		if (insn->src_reg != BPF_PSEUDO_CALL) {
+			pr_warn("prog '%s': incorrect bpf_call opcode\n", prog->name);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		/* text_shndx can be 0, if no default "main" program exists */
+		if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
+			sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
+			pr_warn("prog '%s': bad call relo against '%s' in section '%s'\n",
+				prog->name, sym_name, sym_sec_name);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		if (sym->st_value % BPF_INSN_SZ) {
+			pr_warn("prog '%s': bad call relo against '%s' at offset %zu\n",
+				prog->name, sym_name, (size_t)sym->st_value);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		reloc_desc->type = RELO_CALL;
+		reloc_desc->insn_idx = insn_idx;
+		reloc_desc->sym_off = sym->st_value;
+		return 0;
+	}
+
+	if (!shdr_idx || shdr_idx >= SHN_LORESERVE) {
+		pr_warn("prog '%s': invalid relo against '%s' in special section 0x%x; forgot to initialize global var?..\n",
+			prog->name, sym_name, shdr_idx);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+
+	/* loading subprog addresses */
+	if (sym_is_subprog(sym, obj->efile.text_shndx)) {
+		/* global_func: sym->st_value = offset in the section, insn->imm = 0.
+		 * local_func: sym->st_value = 0, insn->imm = offset in the section.
+		 */
+		if ((sym->st_value % BPF_INSN_SZ) || (insn->imm % BPF_INSN_SZ)) {
+			pr_warn("prog '%s': bad subprog addr relo against '%s' at offset %zu+%d\n",
+				prog->name, sym_name, (size_t)sym->st_value, insn->imm);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+
+		reloc_desc->type = RELO_SUBPROG_ADDR;
+		reloc_desc->insn_idx = insn_idx;
+		reloc_desc->sym_off = sym->st_value;
+		return 0;
+	}
+
+	type = bpf_object__section_to_libbpf_map_type(obj, shdr_idx);
+	sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
+
+	/* generic map reference relocation */
+	if (type == LIBBPF_MAP_UNSPEC) {
+		if (!bpf_object__shndx_is_maps(obj, shdr_idx)) {
+			pr_warn("prog '%s': bad map relo against '%s' in section '%s'\n",
+				prog->name, sym_name, sym_sec_name);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		for (map_idx = 0; map_idx < nr_maps; map_idx++) {
+			map = &obj->maps[map_idx];
+			if (map->libbpf_type != type ||
+			    map->sec_idx != sym->st_shndx ||
+			    map->sec_offset != sym->st_value)
+				continue;
+			pr_debug("prog '%s': found map %zd (%s, sec %d, off %zu) for insn #%u\n",
+				 prog->name, map_idx, map->name, map->sec_idx,
+				 map->sec_offset, insn_idx);
+			break;
+		}
+		if (map_idx >= nr_maps) {
+			pr_warn("prog '%s': map relo failed to find map for section '%s', off %zu\n",
+				prog->name, sym_sec_name, (size_t)sym->st_value);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		reloc_desc->type = RELO_LD64;
+		reloc_desc->insn_idx = insn_idx;
+		reloc_desc->map_idx = map_idx;
+		reloc_desc->sym_off = 0; /* sym->st_value determines map_idx */
+		return 0;
+	}
+
+	/* global data map relocation */
+	if (!bpf_object__shndx_is_data(obj, shdr_idx)) {
+		pr_warn("prog '%s': bad data relo against section '%s'\n",
+			prog->name, sym_sec_name);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+	for (map_idx = 0; map_idx < nr_maps; map_idx++) {
+		map = &obj->maps[map_idx];
+		if (map->libbpf_type != type || map->sec_idx != sym->st_shndx)
+			continue;
+		pr_debug("prog '%s': found data map %zd (%s, sec %d, off %zu) for insn %u\n",
+			 prog->name, map_idx, map->name, map->sec_idx,
+			 map->sec_offset, insn_idx);
+		break;
+	}
+	if (map_idx >= nr_maps) {
+		pr_warn("prog '%s': data relo failed to find map for section '%s'\n",
+			prog->name, sym_sec_name);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+
+	reloc_desc->type = RELO_DATA;
+	reloc_desc->insn_idx = insn_idx;
+	reloc_desc->map_idx = map_idx;
+	reloc_desc->sym_off = sym->st_value;
+	return 0;
+}
+
+static bool prog_contains_insn(const struct bpf_program *prog, size_t insn_idx)
+{
+	return insn_idx >= prog->sec_insn_off &&
+	       insn_idx < prog->sec_insn_off + prog->sec_insn_cnt;
+}
+
+static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj,
+						 size_t sec_idx, size_t insn_idx)
+{
+	int l = 0, r = obj->nr_programs - 1, m;
+	struct bpf_program *prog;
+
+	if (!obj->nr_programs)
+		return NULL;
+
+	while (l < r) {
+		m = l + (r - l + 1) / 2;
+		prog = &obj->programs[m];
+
+		if (prog->sec_idx < sec_idx ||
+		    (prog->sec_idx == sec_idx && prog->sec_insn_off <= insn_idx))
+			l = m;
+		else
+			r = m - 1;
+	}
+	/* matching program could be at index l, but it still might be the
+	 * wrong one, so we need to double check conditions for the last time
+	 */
+	prog = &obj->programs[l];
+	if (prog->sec_idx == sec_idx && prog_contains_insn(prog, insn_idx))
+		return prog;
+	return NULL;
+}
+
+static int
+bpf_object__collect_prog_relos(struct bpf_object *obj, Elf64_Shdr *shdr, Elf_Data *data)
+{
+	const char *relo_sec_name, *sec_name;
+	size_t sec_idx = shdr->sh_info, sym_idx;
+	struct bpf_program *prog;
+	struct reloc_desc *relos;
+	int err, i, nrels;
+	const char *sym_name;
+	__u32 insn_idx;
+	Elf_Scn *scn;
+	Elf_Data *scn_data;
+	Elf64_Sym *sym;
+	Elf64_Rel *rel;
+
+	if (sec_idx >= obj->efile.sec_cnt)
+		return -EINVAL;
+
+	scn = elf_sec_by_idx(obj, sec_idx);
+	scn_data = elf_sec_data(obj, scn);
+
+	relo_sec_name = elf_sec_str(obj, shdr->sh_name);
+	sec_name = elf_sec_name(obj, scn);
+	if (!relo_sec_name || !sec_name)
+		return -EINVAL;
+
+	pr_debug("sec '%s': collecting relocation for section(%zu) '%s'\n",
+		 relo_sec_name, sec_idx, sec_name);
+	nrels = shdr->sh_size / shdr->sh_entsize;
+
+	for (i = 0; i < nrels; i++) {
+		rel = elf_rel_by_idx(data, i);
+		if (!rel) {
+			pr_warn("sec '%s': failed to get relo #%d\n", relo_sec_name, i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		sym_idx = ELF64_R_SYM(rel->r_info);
+		sym = elf_sym_by_idx(obj, sym_idx);
+		if (!sym) {
+			pr_warn("sec '%s': symbol #%zu not found for relo #%d\n",
+				relo_sec_name, sym_idx, i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		if (sym->st_shndx >= obj->efile.sec_cnt) {
+			pr_warn("sec '%s': corrupted symbol #%zu pointing to invalid section #%zu for relo #%d\n",
+				relo_sec_name, sym_idx, (size_t)sym->st_shndx, i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		if (rel->r_offset % BPF_INSN_SZ || rel->r_offset >= scn_data->d_size) {
+			pr_warn("sec '%s': invalid offset 0x%zx for relo #%d\n",
+				relo_sec_name, (size_t)rel->r_offset, i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		insn_idx = rel->r_offset / BPF_INSN_SZ;
+		/* relocations against static functions are recorded as
+		 * relocations against the section that contains a function;
+		 * in such case, symbol will be STT_SECTION and sym.st_name
+		 * will point to empty string (0), so fetch section name
+		 * instead
+		 */
+		if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION && sym->st_name == 0)
+			sym_name = elf_sec_name(obj, elf_sec_by_idx(obj, sym->st_shndx));
+		else
+			sym_name = elf_sym_str(obj, sym->st_name);
+		sym_name = sym_name ?: "<?";
+
+		pr_debug("sec '%s': relo #%d: insn #%u against '%s'\n",
+			 relo_sec_name, i, insn_idx, sym_name);
+
+		prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
+		if (!prog) {
+			pr_debug("sec '%s': relo #%d: couldn't find program in section '%s' for insn #%u, probably overridden weak function, skipping...\n",
+				relo_sec_name, i, sec_name, insn_idx);
+			continue;
+		}
+
+		relos = libbpf_reallocarray(prog->reloc_desc,
+					    prog->nr_reloc + 1, sizeof(*relos));
+		if (!relos)
+			return -ENOMEM;
+		prog->reloc_desc = relos;
+
+		/* adjust insn_idx to local BPF program frame of reference */
+		insn_idx -= prog->sec_insn_off;
+		err = bpf_program__record_reloc(prog, &relos[prog->nr_reloc],
+						insn_idx, sym_name, sym, rel);
+		if (err)
+			return err;
+
+		prog->nr_reloc++;
+	}
+	return 0;
+}
+
+static int bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map)
+{
+	int id;
+
+	if (!obj->btf)
+		return -ENOENT;
+
+	/* if it's BTF-defined map, we don't need to search for type IDs.
+	 * For struct_ops map, it does not need btf_key_type_id and
+	 * btf_value_type_id.
+	 */
+	if (map->sec_idx == obj->efile.btf_maps_shndx || bpf_map__is_struct_ops(map))
+		return 0;
+
+	/*
+	 * LLVM annotates global data differently in BTF, that is,
+	 * only as '.data', '.bss' or '.rodata'.
+	 */
+	if (!bpf_map__is_internal(map))
+		return -ENOENT;
+
+	id = btf__find_by_name(obj->btf, map->real_name);
+	if (id < 0)
+		return id;
+
+	map->btf_key_type_id = 0;
+	map->btf_value_type_id = id;
+	return 0;
+}
+
+static int bpf_get_map_info_from_fdinfo(int fd, struct bpf_map_info *info)
+{
+	char file[PATH_MAX], buff[4096];
+	FILE *fp;
+	__u32 val;
+	int err;
+
+	snprintf(file, sizeof(file), "/proc/%d/fdinfo/%d", getpid(), fd);
+	memset(info, 0, sizeof(*info));
+
+	fp = fopen(file, "r");
+	if (!fp) {
+		err = -errno;
+		pr_warn("failed to open %s: %d. No procfs support?\n", file,
+			err);
+		return err;
+	}
+
+	while (fgets(buff, sizeof(buff), fp)) {
+		if (sscanf(buff, "map_type:\t%u", &val) == 1)
+			info->type = val;
+		else if (sscanf(buff, "key_size:\t%u", &val) == 1)
+			info->key_size = val;
+		else if (sscanf(buff, "value_size:\t%u", &val) == 1)
+			info->value_size = val;
+		else if (sscanf(buff, "max_entries:\t%u", &val) == 1)
+			info->max_entries = val;
+		else if (sscanf(buff, "map_flags:\t%i", &val) == 1)
+			info->map_flags = val;
+	}
+
+	fclose(fp);
+
+	return 0;
+}
+
+bool bpf_map__autocreate(const struct bpf_map *map)
+{
+	return map->autocreate;
+}
+
+int bpf_map__set_autocreate(struct bpf_map *map, bool autocreate)
+{
+	if (map->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	map->autocreate = autocreate;
+	return 0;
+}
+
+int bpf_map__reuse_fd(struct bpf_map *map, int fd)
+{
+	struct bpf_map_info info;
+	__u32 len = sizeof(info), name_len;
+	int new_fd, err;
+	char *new_name;
+
+	memset(&info, 0, len);
+	err = bpf_obj_get_info_by_fd(fd, &info, &len);
+	if (err && errno == EINVAL)
+		err = bpf_get_map_info_from_fdinfo(fd, &info);
+	if (err)
+		return libbpf_err(err);
+
+	name_len = strlen(info.name);
+	if (name_len == BPF_OBJ_NAME_LEN - 1 && strncmp(map->name, info.name, name_len) == 0)
+		new_name = strdup(map->name);
+	else
+		new_name = strdup(info.name);
+
+	if (!new_name)
+		return libbpf_err(-errno);
+
+	new_fd = open("/", O_RDONLY | O_CLOEXEC);
+	if (new_fd < 0) {
+		err = -errno;
+		goto err_free_new_name;
+	}
+
+	new_fd = dup3(fd, new_fd, O_CLOEXEC);
+	if (new_fd < 0) {
+		err = -errno;
+		goto err_close_new_fd;
+	}
+
+	err = zclose(map->fd);
+	if (err) {
+		err = -errno;
+		goto err_close_new_fd;
+	}
+	free(map->name);
+
+	map->fd = new_fd;
+	map->name = new_name;
+	map->def.type = info.type;
+	map->def.key_size = info.key_size;
+	map->def.value_size = info.value_size;
+	map->def.max_entries = info.max_entries;
+	map->def.map_flags = info.map_flags;
+	map->btf_key_type_id = info.btf_key_type_id;
+	map->btf_value_type_id = info.btf_value_type_id;
+	map->reused = true;
+	map->map_extra = info.map_extra;
+
+	return 0;
+
+err_close_new_fd:
+	close(new_fd);
+err_free_new_name:
+	free(new_name);
+	return libbpf_err(err);
+}
+
+__u32 bpf_map__max_entries(const struct bpf_map *map)
+{
+	return map->def.max_entries;
+}
+
+struct bpf_map *bpf_map__inner_map(struct bpf_map *map)
+{
+	if (!bpf_map_type__is_map_in_map(map->def.type))
+		return errno = EINVAL, NULL;
+
+	return map->inner_map;
+}
+
+int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries)
+{
+	if (map->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	map->def.max_entries = max_entries;
+
+	/* auto-adjust BPF ringbuf map max_entries to be a multiple of page size */
+	if (map_is_ringbuf(map))
+		map->def.max_entries = adjust_ringbuf_sz(map->def.max_entries);
+
+	return 0;
+}
+
+static int
+bpf_object__probe_loading(struct bpf_object *obj)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int ret, insn_cnt = ARRAY_SIZE(insns);
+
+	if (obj->gen_loader)
+		return 0;
+
+	ret = bump_rlimit_memlock();
+	if (ret)
+		pr_warn("Failed to bump RLIMIT_MEMLOCK (err = %d), you might need to do it explicitly!\n", ret);
+
+	/* make sure basic loading works */
+	ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
+	if (ret < 0)
+		ret = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, NULL);
+	if (ret < 0) {
+		ret = errno;
+		cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
+		pr_warn("Error in %s():%s(%d). Couldn't load trivial BPF "
+			"program. Make sure your kernel supports BPF "
+			"(CONFIG_BPF_SYSCALL=y) and/or that RLIMIT_MEMLOCK is "
+			"set to big enough value.\n", __func__, cp, ret);
+		return -ret;
+	}
+	close(ret);
+
+	return 0;
+}
+
+static int probe_fd(int fd)
+{
+	if (fd >= 0)
+		close(fd);
+	return fd >= 0;
+}
+
+static int probe_kern_prog_name(void)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, prog_name);
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, attr_sz);
+	attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	attr.license = ptr_to_u64("GPL");
+	attr.insns = ptr_to_u64(insns);
+	attr.insn_cnt = (__u32)ARRAY_SIZE(insns);
+	libbpf_strlcpy(attr.prog_name, "libbpf_nametest", sizeof(attr.prog_name));
+
+	/* make sure loading with name works */
+	ret = sys_bpf_prog_load(&attr, attr_sz, PROG_LOAD_ATTEMPTS);
+	return probe_fd(ret);
+}
+
+static int probe_kern_global_data(void)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct bpf_insn insns[] = {
+		BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16),
+		BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42),
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int ret, map, insn_cnt = ARRAY_SIZE(insns);
+
+	map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_global", sizeof(int), 32, 1, NULL);
+	if (map < 0) {
+		ret = -errno;
+		cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
+		pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
+			__func__, cp, -ret);
+		return ret;
+	}
+
+	insns[0].imm = map;
+
+	ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
+	close(map);
+	return probe_fd(ret);
+}
+
+static int probe_kern_btf(void)
+{
+	static const char strs[] = "\0int";
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_func(void)
+{
+	static const char strs[] = "\0int\0x\0a";
+	/* void x(int a) {} */
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* FUNC_PROTO */                                /* [2] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
+		BTF_PARAM_ENC(7, 1),
+		/* FUNC x */                                    /* [3] */
+		BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_func_global(void)
+{
+	static const char strs[] = "\0int\0x\0a";
+	/* static void x(int a) {} */
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* FUNC_PROTO */                                /* [2] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
+		BTF_PARAM_ENC(7, 1),
+		/* FUNC x BTF_FUNC_GLOBAL */                    /* [3] */
+		BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_datasec(void)
+{
+	static const char strs[] = "\0x\0.data";
+	/* static int a; */
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* VAR x */                                     /* [2] */
+		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
+		BTF_VAR_STATIC,
+		/* DATASEC val */                               /* [3] */
+		BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
+		BTF_VAR_SECINFO_ENC(2, 0, 4),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_float(void)
+{
+	static const char strs[] = "\0float";
+	__u32 types[] = {
+		/* float */
+		BTF_TYPE_FLOAT_ENC(1, 4),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_decl_tag(void)
+{
+	static const char strs[] = "\0tag";
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* VAR x */                                     /* [2] */
+		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
+		BTF_VAR_STATIC,
+		/* attr */
+		BTF_TYPE_DECL_TAG_ENC(1, 2, -1),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_type_tag(void)
+{
+	static const char strs[] = "\0tag";
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),		/* [1] */
+		/* attr */
+		BTF_TYPE_TYPE_TAG_ENC(1, 1),				/* [2] */
+		/* ptr */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 2),	/* [3] */
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_array_mmap(void)
+{
+	LIBBPF_OPTS(bpf_map_create_opts, opts, .map_flags = BPF_F_MMAPABLE);
+	int fd;
+
+	fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_mmap", sizeof(int), sizeof(int), 1, &opts);
+	return probe_fd(fd);
+}
+
+static int probe_kern_exp_attach_type(void)
+{
+	LIBBPF_OPTS(bpf_prog_load_opts, opts, .expected_attach_type = BPF_CGROUP_INET_SOCK_CREATE);
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int fd, insn_cnt = ARRAY_SIZE(insns);
+
+	/* use any valid combination of program type and (optional)
+	 * non-zero expected attach type (i.e., not a BPF_CGROUP_INET_INGRESS)
+	 * to see if kernel supports expected_attach_type field for
+	 * BPF_PROG_LOAD command
+	 */
+	fd = bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCK, NULL, "GPL", insns, insn_cnt, &opts);
+	return probe_fd(fd);
+}
+
+static int probe_kern_probe_read_kernel(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),	/* r1 = r10 (fp) */
+		BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8),	/* r1 += -8 */
+		BPF_MOV64_IMM(BPF_REG_2, 8),		/* r2 = 8 */
+		BPF_MOV64_IMM(BPF_REG_3, 0),		/* r3 = 0 */
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_probe_read_kernel),
+		BPF_EXIT_INSN(),
+	};
+	int fd, insn_cnt = ARRAY_SIZE(insns);
+
+	fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, NULL);
+	return probe_fd(fd);
+}
+
+static int probe_prog_bind_map(void)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int ret, map, prog, insn_cnt = ARRAY_SIZE(insns);
+
+	map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_det_bind", sizeof(int), 32, 1, NULL);
+	if (map < 0) {
+		ret = -errno;
+		cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
+		pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
+			__func__, cp, -ret);
+		return ret;
+	}
+
+	prog = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
+	if (prog < 0) {
+		close(map);
+		return 0;
+	}
+
+	ret = bpf_prog_bind_map(prog, map, NULL);
+
+	close(map);
+	close(prog);
+
+	return ret >= 0;
+}
+
+static int probe_module_btf(void)
+{
+	static const char strs[] = "\0int";
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
+	};
+	struct bpf_btf_info info;
+	__u32 len = sizeof(info);
+	char name[16];
+	int fd, err;
+
+	fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs));
+	if (fd < 0)
+		return 0; /* BTF not supported at all */
+
+	memset(&info, 0, sizeof(info));
+	info.name = ptr_to_u64(name);
+	info.name_len = sizeof(name);
+
+	/* check that BPF_OBJ_GET_INFO_BY_FD supports specifying name pointer;
+	 * kernel's module BTF support coincides with support for
+	 * name/name_len fields in struct bpf_btf_info.
+	 */
+	err = bpf_obj_get_info_by_fd(fd, &info, &len);
+	close(fd);
+	return !err;
+}
+
+static int probe_perf_link(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int prog_fd, link_fd, err;
+
+	prog_fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL",
+				insns, ARRAY_SIZE(insns), NULL);
+	if (prog_fd < 0)
+		return -errno;
+
+	/* use invalid perf_event FD to get EBADF, if link is supported;
+	 * otherwise EINVAL should be returned
+	 */
+	link_fd = bpf_link_create(prog_fd, -1, BPF_PERF_EVENT, NULL);
+	err = -errno; /* close() can clobber errno */
+
+	if (link_fd >= 0)
+		close(link_fd);
+	close(prog_fd);
+
+	return link_fd < 0 && err == -EBADF;
+}
+
+static int probe_kern_bpf_cookie(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_attach_cookie),
+		BPF_EXIT_INSN(),
+	};
+	int ret, insn_cnt = ARRAY_SIZE(insns);
+
+	ret = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", insns, insn_cnt, NULL);
+	return probe_fd(ret);
+}
+
+static int probe_kern_btf_enum64(void)
+{
+	static const char strs[] = "\0enum64";
+	__u32 types[] = {
+		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_ENUM64, 0, 0), 8),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
+static int probe_kern_syscall_wrapper(void);
+
+enum kern_feature_result {
+	FEAT_UNKNOWN = 0,
+	FEAT_SUPPORTED = 1,
+	FEAT_MISSING = 2,
+};
+
+typedef int (*feature_probe_fn)(void);
+
+static struct kern_feature_desc {
+	const char *desc;
+	feature_probe_fn probe;
+	enum kern_feature_result res;
+} feature_probes[__FEAT_CNT] = {
+	[FEAT_PROG_NAME] = {
+		"BPF program name", probe_kern_prog_name,
+	},
+	[FEAT_GLOBAL_DATA] = {
+		"global variables", probe_kern_global_data,
+	},
+	[FEAT_BTF] = {
+		"minimal BTF", probe_kern_btf,
+	},
+	[FEAT_BTF_FUNC] = {
+		"BTF functions", probe_kern_btf_func,
+	},
+	[FEAT_BTF_GLOBAL_FUNC] = {
+		"BTF global function", probe_kern_btf_func_global,
+	},
+	[FEAT_BTF_DATASEC] = {
+		"BTF data section and variable", probe_kern_btf_datasec,
+	},
+	[FEAT_ARRAY_MMAP] = {
+		"ARRAY map mmap()", probe_kern_array_mmap,
+	},
+	[FEAT_EXP_ATTACH_TYPE] = {
+		"BPF_PROG_LOAD expected_attach_type attribute",
+		probe_kern_exp_attach_type,
+	},
+	[FEAT_PROBE_READ_KERN] = {
+		"bpf_probe_read_kernel() helper", probe_kern_probe_read_kernel,
+	},
+	[FEAT_PROG_BIND_MAP] = {
+		"BPF_PROG_BIND_MAP support", probe_prog_bind_map,
+	},
+	[FEAT_MODULE_BTF] = {
+		"module BTF support", probe_module_btf,
+	},
+	[FEAT_BTF_FLOAT] = {
+		"BTF_KIND_FLOAT support", probe_kern_btf_float,
+	},
+	[FEAT_PERF_LINK] = {
+		"BPF perf link support", probe_perf_link,
+	},
+	[FEAT_BTF_DECL_TAG] = {
+		"BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag,
+	},
+	[FEAT_BTF_TYPE_TAG] = {
+		"BTF_KIND_TYPE_TAG support", probe_kern_btf_type_tag,
+	},
+	[FEAT_MEMCG_ACCOUNT] = {
+		"memcg-based memory accounting", probe_memcg_account,
+	},
+	[FEAT_BPF_COOKIE] = {
+		"BPF cookie support", probe_kern_bpf_cookie,
+	},
+	[FEAT_BTF_ENUM64] = {
+		"BTF_KIND_ENUM64 support", probe_kern_btf_enum64,
+	},
+	[FEAT_SYSCALL_WRAPPER] = {
+		"Kernel using syscall wrapper", probe_kern_syscall_wrapper,
+	},
+};
+
+bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)
+{
+	struct kern_feature_desc *feat = &feature_probes[feat_id];
+	int ret;
+
+	if (obj && obj->gen_loader)
+		/* To generate loader program assume the latest kernel
+		 * to avoid doing extra prog_load, map_create syscalls.
+		 */
+		return true;
+
+	if (READ_ONCE(feat->res) == FEAT_UNKNOWN) {
+		ret = feat->probe();
+		if (ret > 0) {
+			WRITE_ONCE(feat->res, FEAT_SUPPORTED);
+		} else if (ret == 0) {
+			WRITE_ONCE(feat->res, FEAT_MISSING);
+		} else {
+			pr_warn("Detection of kernel %s support failed: %d\n", feat->desc, ret);
+			WRITE_ONCE(feat->res, FEAT_MISSING);
+		}
+	}
+
+	return READ_ONCE(feat->res) == FEAT_SUPPORTED;
+}
+
+static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
+{
+	struct bpf_map_info map_info;
+	char msg[STRERR_BUFSIZE];
+	__u32 map_info_len = sizeof(map_info);
+	int err;
+
+	memset(&map_info, 0, map_info_len);
+	err = bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len);
+	if (err && errno == EINVAL)
+		err = bpf_get_map_info_from_fdinfo(map_fd, &map_info);
+	if (err) {
+		pr_warn("failed to get map info for map FD %d: %s\n", map_fd,
+			libbpf_strerror_r(errno, msg, sizeof(msg)));
+		return false;
+	}
+
+	return (map_info.type == map->def.type &&
+		map_info.key_size == map->def.key_size &&
+		map_info.value_size == map->def.value_size &&
+		map_info.max_entries == map->def.max_entries &&
+		map_info.map_flags == map->def.map_flags &&
+		map_info.map_extra == map->map_extra);
+}
+
+static int
+bpf_object__reuse_map(struct bpf_map *map)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err, pin_fd;
+
+	pin_fd = bpf_obj_get(map->pin_path);
+	if (pin_fd < 0) {
+		err = -errno;
+		if (err == -ENOENT) {
+			pr_debug("found no pinned map to reuse at '%s'\n",
+				 map->pin_path);
+			return 0;
+		}
+
+		cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
+		pr_warn("couldn't retrieve pinned map '%s': %s\n",
+			map->pin_path, cp);
+		return err;
+	}
+
+	if (!map_is_reuse_compat(map, pin_fd)) {
+		pr_warn("couldn't reuse pinned map at '%s': parameter mismatch\n",
+			map->pin_path);
+		close(pin_fd);
+		return -EINVAL;
+	}
+
+	err = bpf_map__reuse_fd(map, pin_fd);
+	close(pin_fd);
+	if (err) {
+		return err;
+	}
+	map->pinned = true;
+	pr_debug("reused pinned map at '%s'\n", map->pin_path);
+
+	return 0;
+}
+
+static int
+bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
+{
+	enum libbpf_map_type map_type = map->libbpf_type;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err, zero = 0;
+
+	if (obj->gen_loader) {
+		bpf_gen__map_update_elem(obj->gen_loader, map - obj->maps,
+					 map->mmaped, map->def.value_size);
+		if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG)
+			bpf_gen__map_freeze(obj->gen_loader, map - obj->maps);
+		return 0;
+	}
+	err = bpf_map_update_elem(map->fd, &zero, map->mmaped, 0);
+	if (err) {
+		err = -errno;
+		cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+		pr_warn("Error setting initial map(%s) contents: %s\n",
+			map->name, cp);
+		return err;
+	}
+
+	/* Freeze .rodata and .kconfig map as read-only from syscall side. */
+	if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG) {
+		err = bpf_map_freeze(map->fd);
+		if (err) {
+			err = -errno;
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+			pr_warn("Error freezing map(%s) as read-only: %s\n",
+				map->name, cp);
+			return err;
+		}
+	}
+	return 0;
+}
+
+static void bpf_map__destroy(struct bpf_map *map);
+
+static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, bool is_inner)
+{
+	LIBBPF_OPTS(bpf_map_create_opts, create_attr);
+	struct bpf_map_def *def = &map->def;
+	const char *map_name = NULL;
+	int err = 0;
+
+	if (kernel_supports(obj, FEAT_PROG_NAME))
+		map_name = map->name;
+	create_attr.map_ifindex = map->map_ifindex;
+	create_attr.map_flags = def->map_flags;
+	create_attr.numa_node = map->numa_node;
+	create_attr.map_extra = map->map_extra;
+
+	if (bpf_map__is_struct_ops(map))
+		create_attr.btf_vmlinux_value_type_id = map->btf_vmlinux_value_type_id;
+
+	if (obj->btf && btf__fd(obj->btf) >= 0) {
+		create_attr.btf_fd = btf__fd(obj->btf);
+		create_attr.btf_key_type_id = map->btf_key_type_id;
+		create_attr.btf_value_type_id = map->btf_value_type_id;
+	}
+
+	if (bpf_map_type__is_map_in_map(def->type)) {
+		if (map->inner_map) {
+			err = bpf_object__create_map(obj, map->inner_map, true);
+			if (err) {
+				pr_warn("map '%s': failed to create inner map: %d\n",
+					map->name, err);
+				return err;
+			}
+			map->inner_map_fd = bpf_map__fd(map->inner_map);
+		}
+		if (map->inner_map_fd >= 0)
+			create_attr.inner_map_fd = map->inner_map_fd;
+	}
+
+	switch (def->type) {
+	case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
+	case BPF_MAP_TYPE_CGROUP_ARRAY:
+	case BPF_MAP_TYPE_STACK_TRACE:
+	case BPF_MAP_TYPE_ARRAY_OF_MAPS:
+	case BPF_MAP_TYPE_HASH_OF_MAPS:
+	case BPF_MAP_TYPE_DEVMAP:
+	case BPF_MAP_TYPE_DEVMAP_HASH:
+	case BPF_MAP_TYPE_CPUMAP:
+	case BPF_MAP_TYPE_XSKMAP:
+	case BPF_MAP_TYPE_SOCKMAP:
+	case BPF_MAP_TYPE_SOCKHASH:
+	case BPF_MAP_TYPE_QUEUE:
+	case BPF_MAP_TYPE_STACK:
+		create_attr.btf_fd = 0;
+		create_attr.btf_key_type_id = 0;
+		create_attr.btf_value_type_id = 0;
+		map->btf_key_type_id = 0;
+		map->btf_value_type_id = 0;
+	default:
+		break;
+	}
+
+	if (obj->gen_loader) {
+		bpf_gen__map_create(obj->gen_loader, def->type, map_name,
+				    def->key_size, def->value_size, def->max_entries,
+				    &create_attr, is_inner ? -1 : map - obj->maps);
+		/* Pretend to have valid FD to pass various fd >= 0 checks.
+		 * This fd == 0 will not be used with any syscall and will be reset to -1 eventually.
+		 */
+		map->fd = 0;
+	} else {
+		map->fd = bpf_map_create(def->type, map_name,
+					 def->key_size, def->value_size,
+					 def->max_entries, &create_attr);
+	}
+	if (map->fd < 0 && (create_attr.btf_key_type_id ||
+			    create_attr.btf_value_type_id)) {
+		char *cp, errmsg[STRERR_BUFSIZE];
+
+		err = -errno;
+		cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+		pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
+			map->name, cp, err);
+		create_attr.btf_fd = 0;
+		create_attr.btf_key_type_id = 0;
+		create_attr.btf_value_type_id = 0;
+		map->btf_key_type_id = 0;
+		map->btf_value_type_id = 0;
+		map->fd = bpf_map_create(def->type, map_name,
+					 def->key_size, def->value_size,
+					 def->max_entries, &create_attr);
+	}
+
+	err = map->fd < 0 ? -errno : 0;
+
+	if (bpf_map_type__is_map_in_map(def->type) && map->inner_map) {
+		if (obj->gen_loader)
+			map->inner_map->fd = -1;
+		bpf_map__destroy(map->inner_map);
+		zfree(&map->inner_map);
+	}
+
+	return err;
+}
+
+static int init_map_in_map_slots(struct bpf_object *obj, struct bpf_map *map)
+{
+	const struct bpf_map *targ_map;
+	unsigned int i;
+	int fd, err = 0;
+
+	for (i = 0; i < map->init_slots_sz; i++) {
+		if (!map->init_slots[i])
+			continue;
+
+		targ_map = map->init_slots[i];
+		fd = bpf_map__fd(targ_map);
+
+		if (obj->gen_loader) {
+			bpf_gen__populate_outer_map(obj->gen_loader,
+						    map - obj->maps, i,
+						    targ_map - obj->maps);
+		} else {
+			err = bpf_map_update_elem(map->fd, &i, &fd, 0);
+		}
+		if (err) {
+			err = -errno;
+			pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",
+				map->name, i, targ_map->name, fd, err);
+			return err;
+		}
+		pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
+			 map->name, i, targ_map->name, fd);
+	}
+
+	zfree(&map->init_slots);
+	map->init_slots_sz = 0;
+
+	return 0;
+}
+
+static int init_prog_array_slots(struct bpf_object *obj, struct bpf_map *map)
+{
+	const struct bpf_program *targ_prog;
+	unsigned int i;
+	int fd, err;
+
+	if (obj->gen_loader)
+		return -ENOTSUP;
+
+	for (i = 0; i < map->init_slots_sz; i++) {
+		if (!map->init_slots[i])
+			continue;
+
+		targ_prog = map->init_slots[i];
+		fd = bpf_program__fd(targ_prog);
+
+		err = bpf_map_update_elem(map->fd, &i, &fd, 0);
+		if (err) {
+			err = -errno;
+			pr_warn("map '%s': failed to initialize slot [%d] to prog '%s' fd=%d: %d\n",
+				map->name, i, targ_prog->name, fd, err);
+			return err;
+		}
+		pr_debug("map '%s': slot [%d] set to prog '%s' fd=%d\n",
+			 map->name, i, targ_prog->name, fd);
+	}
+
+	zfree(&map->init_slots);
+	map->init_slots_sz = 0;
+
+	return 0;
+}
+
+static int bpf_object_init_prog_arrays(struct bpf_object *obj)
+{
+	struct bpf_map *map;
+	int i, err;
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		map = &obj->maps[i];
+
+		if (!map->init_slots_sz || map->def.type != BPF_MAP_TYPE_PROG_ARRAY)
+			continue;
+
+		err = init_prog_array_slots(obj, map);
+		if (err < 0) {
+			zclose(map->fd);
+			return err;
+		}
+	}
+	return 0;
+}
+
+static int map_set_def_max_entries(struct bpf_map *map)
+{
+	if (map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !map->def.max_entries) {
+		int nr_cpus;
+
+		nr_cpus = libbpf_num_possible_cpus();
+		if (nr_cpus < 0) {
+			pr_warn("map '%s': failed to determine number of system CPUs: %d\n",
+				map->name, nr_cpus);
+			return nr_cpus;
+		}
+		pr_debug("map '%s': setting size to %d\n", map->name, nr_cpus);
+		map->def.max_entries = nr_cpus;
+	}
+
+	return 0;
+}
+
+static int
+bpf_object__create_maps(struct bpf_object *obj)
+{
+	struct bpf_map *map;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	unsigned int i, j;
+	int err;
+	bool retried;
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		map = &obj->maps[i];
+
+		/* To support old kernels, we skip creating global data maps
+		 * (.rodata, .data, .kconfig, etc); later on, during program
+		 * loading, if we detect that at least one of the to-be-loaded
+		 * programs is referencing any global data map, we'll error
+		 * out with program name and relocation index logged.
+		 * This approach allows to accommodate Clang emitting
+		 * unnecessary .rodata.str1.1 sections for string literals,
+		 * but also it allows to have CO-RE applications that use
+		 * global variables in some of BPF programs, but not others.
+		 * If those global variable-using programs are not loaded at
+		 * runtime due to bpf_program__set_autoload(prog, false),
+		 * bpf_object loading will succeed just fine even on old
+		 * kernels.
+		 */
+		if (bpf_map__is_internal(map) && !kernel_supports(obj, FEAT_GLOBAL_DATA))
+			map->autocreate = false;
+
+		if (!map->autocreate) {
+			pr_debug("map '%s': skipped auto-creating...\n", map->name);
+			continue;
+		}
+
+		err = map_set_def_max_entries(map);
+		if (err)
+			goto err_out;
+
+		retried = false;
+retry:
+		if (map->pin_path) {
+			err = bpf_object__reuse_map(map);
+			if (err) {
+				pr_warn("map '%s': error reusing pinned map\n",
+					map->name);
+				goto err_out;
+			}
+			if (retried && map->fd < 0) {
+				pr_warn("map '%s': cannot find pinned map\n",
+					map->name);
+				err = -ENOENT;
+				goto err_out;
+			}
+		}
+
+		if (map->fd >= 0) {
+			pr_debug("map '%s': skipping creation (preset fd=%d)\n",
+				 map->name, map->fd);
+		} else {
+			err = bpf_object__create_map(obj, map, false);
+			if (err)
+				goto err_out;
+
+			pr_debug("map '%s': created successfully, fd=%d\n",
+				 map->name, map->fd);
+
+			if (bpf_map__is_internal(map)) {
+				err = bpf_object__populate_internal_map(obj, map);
+				if (err < 0) {
+					zclose(map->fd);
+					goto err_out;
+				}
+			}
+
+			if (map->init_slots_sz && map->def.type != BPF_MAP_TYPE_PROG_ARRAY) {
+				err = init_map_in_map_slots(obj, map);
+				if (err < 0) {
+					zclose(map->fd);
+					goto err_out;
+				}
+			}
+		}
+
+		if (map->pin_path && !map->pinned) {
+			err = bpf_map__pin(map, NULL);
+			if (err) {
+				zclose(map->fd);
+				if (!retried && err == -EEXIST) {
+					retried = true;
+					goto retry;
+				}
+				pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
+					map->name, map->pin_path, err);
+				goto err_out;
+			}
+		}
+	}
+
+	return 0;
+
+err_out:
+	cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+	pr_warn("map '%s': failed to create: %s(%d)\n", map->name, cp, err);
+	pr_perm_msg(err);
+	for (j = 0; j < i; j++)
+		zclose(obj->maps[j].fd);
+	return err;
+}
+
+static bool bpf_core_is_flavor_sep(const char *s)
+{
+	/* check X___Y name pattern, where X and Y are not underscores */
+	return s[0] != '_' &&				      /* X */
+	       s[1] == '_' && s[2] == '_' && s[3] == '_' &&   /* ___ */
+	       s[4] != '_';				      /* Y */
+}
+
+/* Given 'some_struct_name___with_flavor' return the length of a name prefix
+ * before last triple underscore. Struct name part after last triple
+ * underscore is ignored by BPF CO-RE relocation during relocation matching.
+ */
+size_t bpf_core_essential_name_len(const char *name)
+{
+	size_t n = strlen(name);
+	int i;
+
+	for (i = n - 5; i >= 0; i--) {
+		if (bpf_core_is_flavor_sep(name + i))
+			return i + 1;
+	}
+	return n;
+}
+
+void bpf_core_free_cands(struct bpf_core_cand_list *cands)
+{
+	if (!cands)
+		return;
+
+	free(cands->cands);
+	free(cands);
+}
+
+int bpf_core_add_cands(struct bpf_core_cand *local_cand,
+		       size_t local_essent_len,
+		       const struct btf *targ_btf,
+		       const char *targ_btf_name,
+		       int targ_start_id,
+		       struct bpf_core_cand_list *cands)
+{
+	struct bpf_core_cand *new_cands, *cand;
+	const struct btf_type *t, *local_t;
+	const char *targ_name, *local_name;
+	size_t targ_essent_len;
+	int n, i;
+
+	local_t = btf__type_by_id(local_cand->btf, local_cand->id);
+	local_name = btf__str_by_offset(local_cand->btf, local_t->name_off);
+
+	n = btf__type_cnt(targ_btf);
+	for (i = targ_start_id; i < n; i++) {
+		t = btf__type_by_id(targ_btf, i);
+		if (!btf_kind_core_compat(t, local_t))
+			continue;
+
+		targ_name = btf__name_by_offset(targ_btf, t->name_off);
+		if (str_is_empty(targ_name))
+			continue;
+
+		targ_essent_len = bpf_core_essential_name_len(targ_name);
+		if (targ_essent_len != local_essent_len)
+			continue;
+
+		if (strncmp(local_name, targ_name, local_essent_len) != 0)
+			continue;
+
+		pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s in [%s]\n",
+			 local_cand->id, btf_kind_str(local_t),
+			 local_name, i, btf_kind_str(t), targ_name,
+			 targ_btf_name);
+		new_cands = libbpf_reallocarray(cands->cands, cands->len + 1,
+					      sizeof(*cands->cands));
+		if (!new_cands)
+			return -ENOMEM;
+
+		cand = &new_cands[cands->len];
+		cand->btf = targ_btf;
+		cand->id = i;
+
+		cands->cands = new_cands;
+		cands->len++;
+	}
+	return 0;
+}
+
+static int load_module_btfs(struct bpf_object *obj)
+{
+	struct bpf_btf_info info;
+	struct module_btf *mod_btf;
+	struct btf *btf;
+	char name[64];
+	__u32 id = 0, len;
+	int err, fd;
+
+	if (obj->btf_modules_loaded)
+		return 0;
+
+	if (obj->gen_loader)
+		return 0;
+
+	/* don't do this again, even if we find no module BTFs */
+	obj->btf_modules_loaded = true;
+
+	/* kernel too old to support module BTFs */
+	if (!kernel_supports(obj, FEAT_MODULE_BTF))
+		return 0;
+
+	while (true) {
+		err = bpf_btf_get_next_id(id, &id);
+		if (err && errno == ENOENT)
+			return 0;
+		if (err) {
+			err = -errno;
+			pr_warn("failed to iterate BTF objects: %d\n", err);
+			return err;
+		}
+
+		fd = bpf_btf_get_fd_by_id(id);
+		if (fd < 0) {
+			if (errno == ENOENT)
+				continue; /* expected race: BTF was unloaded */
+			err = -errno;
+			pr_warn("failed to get BTF object #%d FD: %d\n", id, err);
+			return err;
+		}
+
+		len = sizeof(info);
+		memset(&info, 0, sizeof(info));
+		info.name = ptr_to_u64(name);
+		info.name_len = sizeof(name);
+
+		err = bpf_obj_get_info_by_fd(fd, &info, &len);
+		if (err) {
+			err = -errno;
+			pr_warn("failed to get BTF object #%d info: %d\n", id, err);
+			goto err_out;
+		}
+
+		/* ignore non-module BTFs */
+		if (!info.kernel_btf || strcmp(name, "vmlinux") == 0) {
+			close(fd);
+			continue;
+		}
+
+		btf = btf_get_from_fd(fd, obj->btf_vmlinux);
+		err = libbpf_get_error(btf);
+		if (err) {
+			pr_warn("failed to load module [%s]'s BTF object #%d: %d\n",
+				name, id, err);
+			goto err_out;
+		}
+
+		err = libbpf_ensure_mem((void **)&obj->btf_modules, &obj->btf_module_cap,
+				        sizeof(*obj->btf_modules), obj->btf_module_cnt + 1);
+		if (err)
+			goto err_out;
+
+		mod_btf = &obj->btf_modules[obj->btf_module_cnt++];
+
+		mod_btf->btf = btf;
+		mod_btf->id = id;
+		mod_btf->fd = fd;
+		mod_btf->name = strdup(name);
+		if (!mod_btf->name) {
+			err = -ENOMEM;
+			goto err_out;
+		}
+		continue;
+
+err_out:
+		close(fd);
+		return err;
+	}
+
+	return 0;
+}
+
+static struct bpf_core_cand_list *
+bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id)
+{
+	struct bpf_core_cand local_cand = {};
+	struct bpf_core_cand_list *cands;
+	const struct btf *main_btf;
+	const struct btf_type *local_t;
+	const char *local_name;
+	size_t local_essent_len;
+	int err, i;
+
+	local_cand.btf = local_btf;
+	local_cand.id = local_type_id;
+	local_t = btf__type_by_id(local_btf, local_type_id);
+	if (!local_t)
+		return ERR_PTR(-EINVAL);
+
+	local_name = btf__name_by_offset(local_btf, local_t->name_off);
+	if (str_is_empty(local_name))
+		return ERR_PTR(-EINVAL);
+	local_essent_len = bpf_core_essential_name_len(local_name);
+
+	cands = calloc(1, sizeof(*cands));
+	if (!cands)
+		return ERR_PTR(-ENOMEM);
+
+	/* Attempt to find target candidates in vmlinux BTF first */
+	main_btf = obj->btf_vmlinux_override ?: obj->btf_vmlinux;
+	err = bpf_core_add_cands(&local_cand, local_essent_len, main_btf, "vmlinux", 1, cands);
+	if (err)
+		goto err_out;
+
+	/* if vmlinux BTF has any candidate, don't got for module BTFs */
+	if (cands->len)
+		return cands;
+
+	/* if vmlinux BTF was overridden, don't attempt to load module BTFs */
+	if (obj->btf_vmlinux_override)
+		return cands;
+
+	/* now look through module BTFs, trying to still find candidates */
+	err = load_module_btfs(obj);
+	if (err)
+		goto err_out;
+
+	for (i = 0; i < obj->btf_module_cnt; i++) {
+		err = bpf_core_add_cands(&local_cand, local_essent_len,
+					 obj->btf_modules[i].btf,
+					 obj->btf_modules[i].name,
+					 btf__type_cnt(obj->btf_vmlinux),
+					 cands);
+		if (err)
+			goto err_out;
+	}
+
+	return cands;
+err_out:
+	bpf_core_free_cands(cands);
+	return ERR_PTR(err);
+}
+
+/* Check local and target types for compatibility. This check is used for
+ * type-based CO-RE relocations and follow slightly different rules than
+ * field-based relocations. This function assumes that root types were already
+ * checked for name match. Beyond that initial root-level name check, names
+ * are completely ignored. Compatibility rules are as follows:
+ *   - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs are considered compatible, but
+ *     kind should match for local and target types (i.e., STRUCT is not
+ *     compatible with UNION);
+ *   - for ENUMs, the size is ignored;
+ *   - for INT, size and signedness are ignored;
+ *   - for ARRAY, dimensionality is ignored, element types are checked for
+ *     compatibility recursively;
+ *   - CONST/VOLATILE/RESTRICT modifiers are ignored;
+ *   - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
+ *   - FUNC_PROTOs are compatible if they have compatible signature: same
+ *     number of input args and compatible return and argument types.
+ * These rules are not set in stone and probably will be adjusted as we get
+ * more experience with using BPF CO-RE relocations.
+ */
+int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
+			      const struct btf *targ_btf, __u32 targ_id)
+{
+	return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id, 32);
+}
+
+int bpf_core_types_match(const struct btf *local_btf, __u32 local_id,
+			 const struct btf *targ_btf, __u32 targ_id)
+{
+	return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false, 32);
+}
+
+static size_t bpf_core_hash_fn(const 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;
+}
+
+static int record_relo_core(struct bpf_program *prog,
+			    const struct bpf_core_relo *core_relo, int insn_idx)
+{
+	struct reloc_desc *relos, *relo;
+
+	relos = libbpf_reallocarray(prog->reloc_desc,
+				    prog->nr_reloc + 1, sizeof(*relos));
+	if (!relos)
+		return -ENOMEM;
+	relo = &relos[prog->nr_reloc];
+	relo->type = RELO_CORE;
+	relo->insn_idx = insn_idx;
+	relo->core_relo = core_relo;
+	prog->reloc_desc = relos;
+	prog->nr_reloc++;
+	return 0;
+}
+
+static const struct bpf_core_relo *find_relo_core(struct bpf_program *prog, int insn_idx)
+{
+	struct reloc_desc *relo;
+	int i;
+
+	for (i = 0; i < prog->nr_reloc; i++) {
+		relo = &prog->reloc_desc[i];
+		if (relo->type != RELO_CORE || relo->insn_idx != insn_idx)
+			continue;
+
+		return relo->core_relo;
+	}
+
+	return NULL;
+}
+
+static int bpf_core_resolve_relo(struct bpf_program *prog,
+				 const struct bpf_core_relo *relo,
+				 int relo_idx,
+				 const struct btf *local_btf,
+				 struct hashmap *cand_cache,
+				 struct bpf_core_relo_res *targ_res)
+{
+	struct bpf_core_spec specs_scratch[3] = {};
+	const void *type_key = u32_as_hash_key(relo->type_id);
+	struct bpf_core_cand_list *cands = NULL;
+	const char *prog_name = prog->name;
+	const struct btf_type *local_type;
+	const char *local_name;
+	__u32 local_id = relo->type_id;
+	int err;
+
+	local_type = btf__type_by_id(local_btf, local_id);
+	if (!local_type)
+		return -EINVAL;
+
+	local_name = btf__name_by_offset(local_btf, local_type->name_off);
+	if (!local_name)
+		return -EINVAL;
+
+	if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
+	    !hashmap__find(cand_cache, type_key, (void **)&cands)) {
+		cands = bpf_core_find_cands(prog->obj, local_btf, local_id);
+		if (IS_ERR(cands)) {
+			pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n",
+				prog_name, relo_idx, local_id, btf_kind_str(local_type),
+				local_name, PTR_ERR(cands));
+			return PTR_ERR(cands);
+		}
+		err = hashmap__set(cand_cache, type_key, cands, NULL, NULL);
+		if (err) {
+			bpf_core_free_cands(cands);
+			return err;
+		}
+	}
+
+	return bpf_core_calc_relo_insn(prog_name, relo, relo_idx, local_btf, cands, specs_scratch,
+				       targ_res);
+}
+
+static int
+bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
+{
+	const struct btf_ext_info_sec *sec;
+	struct bpf_core_relo_res targ_res;
+	const struct bpf_core_relo *rec;
+	const struct btf_ext_info *seg;
+	struct hashmap_entry *entry;
+	struct hashmap *cand_cache = NULL;
+	struct bpf_program *prog;
+	struct bpf_insn *insn;
+	const char *sec_name;
+	int i, err = 0, insn_idx, sec_idx, sec_num;
+
+	if (obj->btf_ext->core_relo_info.len == 0)
+		return 0;
+
+	if (targ_btf_path) {
+		obj->btf_vmlinux_override = btf__parse(targ_btf_path, NULL);
+		err = libbpf_get_error(obj->btf_vmlinux_override);
+		if (err) {
+			pr_warn("failed to parse target BTF: %d\n", err);
+			return err;
+		}
+	}
+
+	cand_cache = hashmap__new(bpf_core_hash_fn, bpf_core_equal_fn, NULL);
+	if (IS_ERR(cand_cache)) {
+		err = PTR_ERR(cand_cache);
+		goto out;
+	}
+
+	seg = &obj->btf_ext->core_relo_info;
+	sec_num = 0;
+	for_each_btf_ext_sec(seg, sec) {
+		sec_idx = seg->sec_idxs[sec_num];
+		sec_num++;
+
+		sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
+		if (str_is_empty(sec_name)) {
+			err = -EINVAL;
+			goto out;
+		}
+
+		pr_debug("sec '%s': found %d CO-RE relocations\n", sec_name, sec->num_info);
+
+		for_each_btf_ext_rec(seg, sec, i, rec) {
+			if (rec->insn_off % BPF_INSN_SZ)
+				return -EINVAL;
+			insn_idx = rec->insn_off / BPF_INSN_SZ;
+			prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
+			if (!prog) {
+				/* When __weak subprog is "overridden" by another instance
+				 * of the subprog from a different object file, linker still
+				 * appends all the .BTF.ext info that used to belong to that
+				 * eliminated subprogram.
+				 * This is similar to what x86-64 linker does for relocations.
+				 * So just ignore such relocations just like we ignore
+				 * subprog instructions when discovering subprograms.
+				 */
+				pr_debug("sec '%s': skipping CO-RE relocation #%d for insn #%d belonging to eliminated weak subprogram\n",
+					 sec_name, i, insn_idx);
+				continue;
+			}
+			/* no need to apply CO-RE relocation if the program is
+			 * not going to be loaded
+			 */
+			if (!prog->autoload)
+				continue;
+
+			/* adjust insn_idx from section frame of reference to the local
+			 * program's frame of reference; (sub-)program code is not yet
+			 * relocated, so it's enough to just subtract in-section offset
+			 */
+			insn_idx = insn_idx - prog->sec_insn_off;
+			if (insn_idx >= prog->insns_cnt)
+				return -EINVAL;
+			insn = &prog->insns[insn_idx];
+
+			err = record_relo_core(prog, rec, insn_idx);
+			if (err) {
+				pr_warn("prog '%s': relo #%d: failed to record relocation: %d\n",
+					prog->name, i, err);
+				goto out;
+			}
+
+			if (prog->obj->gen_loader)
+				continue;
+
+			err = bpf_core_resolve_relo(prog, rec, i, obj->btf, cand_cache, &targ_res);
+			if (err) {
+				pr_warn("prog '%s': relo #%d: failed to relocate: %d\n",
+					prog->name, i, err);
+				goto out;
+			}
+
+			err = bpf_core_patch_insn(prog->name, insn, insn_idx, rec, i, &targ_res);
+			if (err) {
+				pr_warn("prog '%s': relo #%d: failed to patch insn #%u: %d\n",
+					prog->name, i, insn_idx, err);
+				goto out;
+			}
+		}
+	}
+
+out:
+	/* obj->btf_vmlinux and module BTFs are freed after object load */
+	btf__free(obj->btf_vmlinux_override);
+	obj->btf_vmlinux_override = NULL;
+
+	if (!IS_ERR_OR_NULL(cand_cache)) {
+		hashmap__for_each_entry(cand_cache, entry, i) {
+			bpf_core_free_cands(entry->value);
+		}
+		hashmap__free(cand_cache);
+	}
+	return err;
+}
+
+/* base map load ldimm64 special constant, used also for log fixup logic */
+#define MAP_LDIMM64_POISON_BASE 2001000000
+#define MAP_LDIMM64_POISON_PFX "200100"
+
+static void poison_map_ldimm64(struct bpf_program *prog, int relo_idx,
+			       int insn_idx, struct bpf_insn *insn,
+			       int map_idx, const struct bpf_map *map)
+{
+	int i;
+
+	pr_debug("prog '%s': relo #%d: poisoning insn #%d that loads map #%d '%s'\n",
+		 prog->name, relo_idx, insn_idx, map_idx, map->name);
+
+	/* we turn single ldimm64 into two identical invalid calls */
+	for (i = 0; i < 2; i++) {
+		insn->code = BPF_JMP | BPF_CALL;
+		insn->dst_reg = 0;
+		insn->src_reg = 0;
+		insn->off = 0;
+		/* if this instruction is reachable (not a dead code),
+		 * verifier will complain with something like:
+		 * invalid func unknown#2001000123
+		 * where lower 123 is map index into obj->maps[] array
+		 */
+		insn->imm = MAP_LDIMM64_POISON_BASE + map_idx;
+
+		insn++;
+	}
+}
+
+/* Relocate data references within program code:
+ *  - map references;
+ *  - global variable references;
+ *  - extern references.
+ */
+static int
+bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
+{
+	int i;
+
+	for (i = 0; i < prog->nr_reloc; i++) {
+		struct reloc_desc *relo = &prog->reloc_desc[i];
+		struct bpf_insn *insn = &prog->insns[relo->insn_idx];
+		const struct bpf_map *map;
+		struct extern_desc *ext;
+
+		switch (relo->type) {
+		case RELO_LD64:
+			map = &obj->maps[relo->map_idx];
+			if (obj->gen_loader) {
+				insn[0].src_reg = BPF_PSEUDO_MAP_IDX;
+				insn[0].imm = relo->map_idx;
+			} else if (map->autocreate) {
+				insn[0].src_reg = BPF_PSEUDO_MAP_FD;
+				insn[0].imm = map->fd;
+			} else {
+				poison_map_ldimm64(prog, i, relo->insn_idx, insn,
+						   relo->map_idx, map);
+			}
+			break;
+		case RELO_DATA:
+			map = &obj->maps[relo->map_idx];
+			insn[1].imm = insn[0].imm + relo->sym_off;
+			if (obj->gen_loader) {
+				insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
+				insn[0].imm = relo->map_idx;
+			} else if (map->autocreate) {
+				insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
+				insn[0].imm = map->fd;
+			} else {
+				poison_map_ldimm64(prog, i, relo->insn_idx, insn,
+						   relo->map_idx, map);
+			}
+			break;
+		case RELO_EXTERN_VAR:
+			ext = &obj->externs[relo->sym_off];
+			if (ext->type == EXT_KCFG) {
+				if (obj->gen_loader) {
+					insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
+					insn[0].imm = obj->kconfig_map_idx;
+				} else {
+					insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
+					insn[0].imm = obj->maps[obj->kconfig_map_idx].fd;
+				}
+				insn[1].imm = ext->kcfg.data_off;
+			} else /* EXT_KSYM */ {
+				if (ext->ksym.type_id && ext->is_set) { /* typed ksyms */
+					insn[0].src_reg = BPF_PSEUDO_BTF_ID;
+					insn[0].imm = ext->ksym.kernel_btf_id;
+					insn[1].imm = ext->ksym.kernel_btf_obj_fd;
+				} else { /* typeless ksyms or unresolved typed ksyms */
+					insn[0].imm = (__u32)ext->ksym.addr;
+					insn[1].imm = ext->ksym.addr >> 32;
+				}
+			}
+			break;
+		case RELO_EXTERN_FUNC:
+			ext = &obj->externs[relo->sym_off];
+			insn[0].src_reg = BPF_PSEUDO_KFUNC_CALL;
+			if (ext->is_set) {
+				insn[0].imm = ext->ksym.kernel_btf_id;
+				insn[0].off = ext->ksym.btf_fd_idx;
+			} else { /* unresolved weak kfunc */
+				insn[0].imm = 0;
+				insn[0].off = 0;
+			}
+			break;
+		case RELO_SUBPROG_ADDR:
+			if (insn[0].src_reg != BPF_PSEUDO_FUNC) {
+				pr_warn("prog '%s': relo #%d: bad insn\n",
+					prog->name, i);
+				return -EINVAL;
+			}
+			/* handled already */
+			break;
+		case RELO_CALL:
+			/* handled already */
+			break;
+		case RELO_CORE:
+			/* will be handled by bpf_program_record_relos() */
+			break;
+		default:
+			pr_warn("prog '%s': relo #%d: bad relo type %d\n",
+				prog->name, i, relo->type);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int adjust_prog_btf_ext_info(const struct bpf_object *obj,
+				    const struct bpf_program *prog,
+				    const struct btf_ext_info *ext_info,
+				    void **prog_info, __u32 *prog_rec_cnt,
+				    __u32 *prog_rec_sz)
+{
+	void *copy_start = NULL, *copy_end = NULL;
+	void *rec, *rec_end, *new_prog_info;
+	const struct btf_ext_info_sec *sec;
+	size_t old_sz, new_sz;
+	int i, sec_num, sec_idx, off_adj;
+
+	sec_num = 0;
+	for_each_btf_ext_sec(ext_info, sec) {
+		sec_idx = ext_info->sec_idxs[sec_num];
+		sec_num++;
+		if (prog->sec_idx != sec_idx)
+			continue;
+
+		for_each_btf_ext_rec(ext_info, sec, i, rec) {
+			__u32 insn_off = *(__u32 *)rec / BPF_INSN_SZ;
+
+			if (insn_off < prog->sec_insn_off)
+				continue;
+			if (insn_off >= prog->sec_insn_off + prog->sec_insn_cnt)
+				break;
+
+			if (!copy_start)
+				copy_start = rec;
+			copy_end = rec + ext_info->rec_size;
+		}
+
+		if (!copy_start)
+			return -ENOENT;
+
+		/* append func/line info of a given (sub-)program to the main
+		 * program func/line info
+		 */
+		old_sz = (size_t)(*prog_rec_cnt) * ext_info->rec_size;
+		new_sz = old_sz + (copy_end - copy_start);
+		new_prog_info = realloc(*prog_info, new_sz);
+		if (!new_prog_info)
+			return -ENOMEM;
+		*prog_info = new_prog_info;
+		*prog_rec_cnt = new_sz / ext_info->rec_size;
+		memcpy(new_prog_info + old_sz, copy_start, copy_end - copy_start);
+
+		/* Kernel instruction offsets are in units of 8-byte
+		 * instructions, while .BTF.ext instruction offsets generated
+		 * by Clang are in units of bytes. So convert Clang offsets
+		 * into kernel offsets and adjust offset according to program
+		 * relocated position.
+		 */
+		off_adj = prog->sub_insn_off - prog->sec_insn_off;
+		rec = new_prog_info + old_sz;
+		rec_end = new_prog_info + new_sz;
+		for (; rec < rec_end; rec += ext_info->rec_size) {
+			__u32 *insn_off = rec;
+
+			*insn_off = *insn_off / BPF_INSN_SZ + off_adj;
+		}
+		*prog_rec_sz = ext_info->rec_size;
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+static int
+reloc_prog_func_and_line_info(const struct bpf_object *obj,
+			      struct bpf_program *main_prog,
+			      const struct bpf_program *prog)
+{
+	int err;
+
+	/* no .BTF.ext relocation if .BTF.ext is missing or kernel doesn't
+	 * supprot func/line info
+	 */
+	if (!obj->btf_ext || !kernel_supports(obj, FEAT_BTF_FUNC))
+		return 0;
+
+	/* only attempt func info relocation if main program's func_info
+	 * relocation was successful
+	 */
+	if (main_prog != prog && !main_prog->func_info)
+		goto line_info;
+
+	err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->func_info,
+				       &main_prog->func_info,
+				       &main_prog->func_info_cnt,
+				       &main_prog->func_info_rec_size);
+	if (err) {
+		if (err != -ENOENT) {
+			pr_warn("prog '%s': error relocating .BTF.ext function info: %d\n",
+				prog->name, err);
+			return err;
+		}
+		if (main_prog->func_info) {
+			/*
+			 * Some info has already been found but has problem
+			 * in the last btf_ext reloc. Must have to error out.
+			 */
+			pr_warn("prog '%s': missing .BTF.ext function info.\n", prog->name);
+			return err;
+		}
+		/* Have problem loading the very first info. Ignore the rest. */
+		pr_warn("prog '%s': missing .BTF.ext function info for the main program, skipping all of .BTF.ext func info.\n",
+			prog->name);
+	}
+
+line_info:
+	/* don't relocate line info if main program's relocation failed */
+	if (main_prog != prog && !main_prog->line_info)
+		return 0;
+
+	err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->line_info,
+				       &main_prog->line_info,
+				       &main_prog->line_info_cnt,
+				       &main_prog->line_info_rec_size);
+	if (err) {
+		if (err != -ENOENT) {
+			pr_warn("prog '%s': error relocating .BTF.ext line info: %d\n",
+				prog->name, err);
+			return err;
+		}
+		if (main_prog->line_info) {
+			/*
+			 * Some info has already been found but has problem
+			 * in the last btf_ext reloc. Must have to error out.
+			 */
+			pr_warn("prog '%s': missing .BTF.ext line info.\n", prog->name);
+			return err;
+		}
+		/* Have problem loading the very first info. Ignore the rest. */
+		pr_warn("prog '%s': missing .BTF.ext line info for the main program, skipping all of .BTF.ext line info.\n",
+			prog->name);
+	}
+	return 0;
+}
+
+static int cmp_relo_by_insn_idx(const void *key, const void *elem)
+{
+	size_t insn_idx = *(const size_t *)key;
+	const struct reloc_desc *relo = elem;
+
+	if (insn_idx == relo->insn_idx)
+		return 0;
+	return insn_idx < relo->insn_idx ? -1 : 1;
+}
+
+static struct reloc_desc *find_prog_insn_relo(const struct bpf_program *prog, size_t insn_idx)
+{
+	if (!prog->nr_reloc)
+		return NULL;
+	return bsearch(&insn_idx, prog->reloc_desc, prog->nr_reloc,
+		       sizeof(*prog->reloc_desc), cmp_relo_by_insn_idx);
+}
+
+static int append_subprog_relos(struct bpf_program *main_prog, struct bpf_program *subprog)
+{
+	int new_cnt = main_prog->nr_reloc + subprog->nr_reloc;
+	struct reloc_desc *relos;
+	int i;
+
+	if (main_prog == subprog)
+		return 0;
+	relos = libbpf_reallocarray(main_prog->reloc_desc, new_cnt, sizeof(*relos));
+	/* if new count is zero, reallocarray can return a valid NULL result;
+	 * in this case the previous pointer will be freed, so we *have to*
+	 * reassign old pointer to the new value (even if it's NULL)
+	 */
+	if (!relos && new_cnt)
+		return -ENOMEM;
+	if (subprog->nr_reloc)
+		memcpy(relos + main_prog->nr_reloc, subprog->reloc_desc,
+		       sizeof(*relos) * subprog->nr_reloc);
+
+	for (i = main_prog->nr_reloc; i < new_cnt; i++)
+		relos[i].insn_idx += subprog->sub_insn_off;
+	/* After insn_idx adjustment the 'relos' array is still sorted
+	 * by insn_idx and doesn't break bsearch.
+	 */
+	main_prog->reloc_desc = relos;
+	main_prog->nr_reloc = new_cnt;
+	return 0;
+}
+
+static int
+bpf_object__reloc_code(struct bpf_object *obj, struct bpf_program *main_prog,
+		       struct bpf_program *prog)
+{
+	size_t sub_insn_idx, insn_idx, new_cnt;
+	struct bpf_program *subprog;
+	struct bpf_insn *insns, *insn;
+	struct reloc_desc *relo;
+	int err;
+
+	err = reloc_prog_func_and_line_info(obj, main_prog, prog);
+	if (err)
+		return err;
+
+	for (insn_idx = 0; insn_idx < prog->sec_insn_cnt; insn_idx++) {
+		insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
+		if (!insn_is_subprog_call(insn) && !insn_is_pseudo_func(insn))
+			continue;
+
+		relo = find_prog_insn_relo(prog, insn_idx);
+		if (relo && relo->type == RELO_EXTERN_FUNC)
+			/* kfunc relocations will be handled later
+			 * in bpf_object__relocate_data()
+			 */
+			continue;
+		if (relo && relo->type != RELO_CALL && relo->type != RELO_SUBPROG_ADDR) {
+			pr_warn("prog '%s': unexpected relo for insn #%zu, type %d\n",
+				prog->name, insn_idx, relo->type);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		if (relo) {
+			/* sub-program instruction index is a combination of
+			 * an offset of a symbol pointed to by relocation and
+			 * call instruction's imm field; for global functions,
+			 * call always has imm = -1, but for static functions
+			 * relocation is against STT_SECTION and insn->imm
+			 * points to a start of a static function
+			 *
+			 * for subprog addr relocation, the relo->sym_off + insn->imm is
+			 * the byte offset in the corresponding section.
+			 */
+			if (relo->type == RELO_CALL)
+				sub_insn_idx = relo->sym_off / BPF_INSN_SZ + insn->imm + 1;
+			else
+				sub_insn_idx = (relo->sym_off + insn->imm) / BPF_INSN_SZ;
+		} else if (insn_is_pseudo_func(insn)) {
+			/*
+			 * RELO_SUBPROG_ADDR relo is always emitted even if both
+			 * functions are in the same section, so it shouldn't reach here.
+			 */
+			pr_warn("prog '%s': missing subprog addr relo for insn #%zu\n",
+				prog->name, insn_idx);
+			return -LIBBPF_ERRNO__RELOC;
+		} else {
+			/* if subprogram call is to a static function within
+			 * the same ELF section, there won't be any relocation
+			 * emitted, but it also means there is no additional
+			 * offset necessary, insns->imm is relative to
+			 * instruction's original position within the section
+			 */
+			sub_insn_idx = prog->sec_insn_off + insn_idx + insn->imm + 1;
+		}
+
+		/* we enforce that sub-programs should be in .text section */
+		subprog = find_prog_by_sec_insn(obj, obj->efile.text_shndx, sub_insn_idx);
+		if (!subprog) {
+			pr_warn("prog '%s': no .text section found yet sub-program call exists\n",
+				prog->name);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+
+		/* if it's the first call instruction calling into this
+		 * subprogram (meaning this subprog hasn't been processed
+		 * yet) within the context of current main program:
+		 *   - append it at the end of main program's instructions blog;
+		 *   - process is recursively, while current program is put on hold;
+		 *   - if that subprogram calls some other not yet processes
+		 *   subprogram, same thing will happen recursively until
+		 *   there are no more unprocesses subprograms left to append
+		 *   and relocate.
+		 */
+		if (subprog->sub_insn_off == 0) {
+			subprog->sub_insn_off = main_prog->insns_cnt;
+
+			new_cnt = main_prog->insns_cnt + subprog->insns_cnt;
+			insns = libbpf_reallocarray(main_prog->insns, new_cnt, sizeof(*insns));
+			if (!insns) {
+				pr_warn("prog '%s': failed to realloc prog code\n", main_prog->name);
+				return -ENOMEM;
+			}
+			main_prog->insns = insns;
+			main_prog->insns_cnt = new_cnt;
+
+			memcpy(main_prog->insns + subprog->sub_insn_off, subprog->insns,
+			       subprog->insns_cnt * sizeof(*insns));
+
+			pr_debug("prog '%s': added %zu insns from sub-prog '%s'\n",
+				 main_prog->name, subprog->insns_cnt, subprog->name);
+
+			/* The subprog insns are now appended. Append its relos too. */
+			err = append_subprog_relos(main_prog, subprog);
+			if (err)
+				return err;
+			err = bpf_object__reloc_code(obj, main_prog, subprog);
+			if (err)
+				return err;
+		}
+
+		/* main_prog->insns memory could have been re-allocated, so
+		 * calculate pointer again
+		 */
+		insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
+		/* calculate correct instruction position within current main
+		 * prog; each main prog can have a different set of
+		 * subprograms appended (potentially in different order as
+		 * well), so position of any subprog can be different for
+		 * different main programs */
+		insn->imm = subprog->sub_insn_off - (prog->sub_insn_off + insn_idx) - 1;
+
+		pr_debug("prog '%s': insn #%zu relocated, imm %d points to subprog '%s' (now at %zu offset)\n",
+			 prog->name, insn_idx, insn->imm, subprog->name, subprog->sub_insn_off);
+	}
+
+	return 0;
+}
+
+/*
+ * Relocate sub-program calls.
+ *
+ * Algorithm operates as follows. Each entry-point BPF program (referred to as
+ * main prog) is processed separately. For each subprog (non-entry functions,
+ * that can be called from either entry progs or other subprogs) gets their
+ * sub_insn_off reset to zero. This serves as indicator that this subprogram
+ * hasn't been yet appended and relocated within current main prog. Once its
+ * relocated, sub_insn_off will point at the position within current main prog
+ * where given subprog was appended. This will further be used to relocate all
+ * the call instructions jumping into this subprog.
+ *
+ * We start with main program and process all call instructions. If the call
+ * is into a subprog that hasn't been processed (i.e., subprog->sub_insn_off
+ * is zero), subprog instructions are appended at the end of main program's
+ * instruction array. Then main program is "put on hold" while we recursively
+ * process newly appended subprogram. If that subprogram calls into another
+ * subprogram that hasn't been appended, new subprogram is appended again to
+ * the *main* prog's instructions (subprog's instructions are always left
+ * untouched, as they need to be in unmodified state for subsequent main progs
+ * and subprog instructions are always sent only as part of a main prog) and
+ * the process continues recursively. Once all the subprogs called from a main
+ * prog or any of its subprogs are appended (and relocated), all their
+ * positions within finalized instructions array are known, so it's easy to
+ * rewrite call instructions with correct relative offsets, corresponding to
+ * desired target subprog.
+ *
+ * Its important to realize that some subprogs might not be called from some
+ * main prog and any of its called/used subprogs. Those will keep their
+ * subprog->sub_insn_off as zero at all times and won't be appended to current
+ * main prog and won't be relocated within the context of current main prog.
+ * They might still be used from other main progs later.
+ *
+ * Visually this process can be shown as below. Suppose we have two main
+ * programs mainA and mainB and BPF object contains three subprogs: subA,
+ * subB, and subC. mainA calls only subA, mainB calls only subC, but subA and
+ * subC both call subB:
+ *
+ *        +--------+ +-------+
+ *        |        v v       |
+ *     +--+---+ +--+-+-+ +---+--+
+ *     | subA | | subB | | subC |
+ *     +--+---+ +------+ +---+--+
+ *        ^                  ^
+ *        |                  |
+ *    +---+-------+   +------+----+
+ *    |   mainA   |   |   mainB   |
+ *    +-----------+   +-----------+
+ *
+ * We'll start relocating mainA, will find subA, append it and start
+ * processing sub A recursively:
+ *
+ *    +-----------+------+
+ *    |   mainA   | subA |
+ *    +-----------+------+
+ *
+ * At this point we notice that subB is used from subA, so we append it and
+ * relocate (there are no further subcalls from subB):
+ *
+ *    +-----------+------+------+
+ *    |   mainA   | subA | subB |
+ *    +-----------+------+------+
+ *
+ * At this point, we relocate subA calls, then go one level up and finish with
+ * relocatin mainA calls. mainA is done.
+ *
+ * For mainB process is similar but results in different order. We start with
+ * mainB and skip subA and subB, as mainB never calls them (at least
+ * directly), but we see subC is needed, so we append and start processing it:
+ *
+ *    +-----------+------+
+ *    |   mainB   | subC |
+ *    +-----------+------+
+ * Now we see subC needs subB, so we go back to it, append and relocate it:
+ *
+ *    +-----------+------+------+
+ *    |   mainB   | subC | subB |
+ *    +-----------+------+------+
+ *
+ * At this point we unwind recursion, relocate calls in subC, then in mainB.
+ */
+static int
+bpf_object__relocate_calls(struct bpf_object *obj, struct bpf_program *prog)
+{
+	struct bpf_program *subprog;
+	int i, err;
+
+	/* mark all subprogs as not relocated (yet) within the context of
+	 * current main program
+	 */
+	for (i = 0; i < obj->nr_programs; i++) {
+		subprog = &obj->programs[i];
+		if (!prog_is_subprog(obj, subprog))
+			continue;
+
+		subprog->sub_insn_off = 0;
+	}
+
+	err = bpf_object__reloc_code(obj, prog, prog);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static void
+bpf_object__free_relocs(struct bpf_object *obj)
+{
+	struct bpf_program *prog;
+	int i;
+
+	/* free up relocation descriptors */
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		zfree(&prog->reloc_desc);
+		prog->nr_reloc = 0;
+	}
+}
+
+static int cmp_relocs(const void *_a, const void *_b)
+{
+	const struct reloc_desc *a = _a;
+	const struct reloc_desc *b = _b;
+
+	if (a->insn_idx != b->insn_idx)
+		return a->insn_idx < b->insn_idx ? -1 : 1;
+
+	/* no two relocations should have the same insn_idx, but ... */
+	if (a->type != b->type)
+		return a->type < b->type ? -1 : 1;
+
+	return 0;
+}
+
+static void bpf_object__sort_relos(struct bpf_object *obj)
+{
+	int i;
+
+	for (i = 0; i < obj->nr_programs; i++) {
+		struct bpf_program *p = &obj->programs[i];
+
+		if (!p->nr_reloc)
+			continue;
+
+		qsort(p->reloc_desc, p->nr_reloc, sizeof(*p->reloc_desc), cmp_relocs);
+	}
+}
+
+static int
+bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
+{
+	struct bpf_program *prog;
+	size_t i, j;
+	int err;
+
+	if (obj->btf_ext) {
+		err = bpf_object__relocate_core(obj, targ_btf_path);
+		if (err) {
+			pr_warn("failed to perform CO-RE relocations: %d\n",
+				err);
+			return err;
+		}
+		bpf_object__sort_relos(obj);
+	}
+
+	/* Before relocating calls pre-process relocations and mark
+	 * few ld_imm64 instructions that points to subprogs.
+	 * Otherwise bpf_object__reloc_code() later would have to consider
+	 * all ld_imm64 insns as relocation candidates. That would
+	 * reduce relocation speed, since amount of find_prog_insn_relo()
+	 * would increase and most of them will fail to find a relo.
+	 */
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		for (j = 0; j < prog->nr_reloc; j++) {
+			struct reloc_desc *relo = &prog->reloc_desc[j];
+			struct bpf_insn *insn = &prog->insns[relo->insn_idx];
+
+			/* mark the insn, so it's recognized by insn_is_pseudo_func() */
+			if (relo->type == RELO_SUBPROG_ADDR)
+				insn[0].src_reg = BPF_PSEUDO_FUNC;
+		}
+	}
+
+	/* relocate subprogram calls and append used subprograms to main
+	 * programs; each copy of subprogram code needs to be relocated
+	 * differently for each main program, because its code location might
+	 * have changed.
+	 * Append subprog relos to main programs to allow data relos to be
+	 * processed after text is completely relocated.
+	 */
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		/* sub-program's sub-calls are relocated within the context of
+		 * its main program only
+		 */
+		if (prog_is_subprog(obj, prog))
+			continue;
+		if (!prog->autoload)
+			continue;
+
+		err = bpf_object__relocate_calls(obj, prog);
+		if (err) {
+			pr_warn("prog '%s': failed to relocate calls: %d\n",
+				prog->name, err);
+			return err;
+		}
+	}
+	/* Process data relos for main programs */
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		if (prog_is_subprog(obj, prog))
+			continue;
+		if (!prog->autoload)
+			continue;
+		err = bpf_object__relocate_data(obj, prog);
+		if (err) {
+			pr_warn("prog '%s': failed to relocate data references: %d\n",
+				prog->name, err);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
+					    Elf64_Shdr *shdr, Elf_Data *data);
+
+static int bpf_object__collect_map_relos(struct bpf_object *obj,
+					 Elf64_Shdr *shdr, Elf_Data *data)
+{
+	const int bpf_ptr_sz = 8, host_ptr_sz = sizeof(void *);
+	int i, j, nrels, new_sz;
+	const struct btf_var_secinfo *vi = NULL;
+	const struct btf_type *sec, *var, *def;
+	struct bpf_map *map = NULL, *targ_map = NULL;
+	struct bpf_program *targ_prog = NULL;
+	bool is_prog_array, is_map_in_map;
+	const struct btf_member *member;
+	const char *name, *mname, *type;
+	unsigned int moff;
+	Elf64_Sym *sym;
+	Elf64_Rel *rel;
+	void *tmp;
+
+	if (!obj->efile.btf_maps_sec_btf_id || !obj->btf)
+		return -EINVAL;
+	sec = btf__type_by_id(obj->btf, obj->efile.btf_maps_sec_btf_id);
+	if (!sec)
+		return -EINVAL;
+
+	nrels = shdr->sh_size / shdr->sh_entsize;
+	for (i = 0; i < nrels; i++) {
+		rel = elf_rel_by_idx(data, i);
+		if (!rel) {
+			pr_warn(".maps relo #%d: failed to get ELF relo\n", i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info));
+		if (!sym) {
+			pr_warn(".maps relo #%d: symbol %zx not found\n",
+				i, (size_t)ELF64_R_SYM(rel->r_info));
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+		name = elf_sym_str(obj, sym->st_name) ?: "<?>";
+
+		pr_debug(".maps relo #%d: for %zd value %zd rel->r_offset %zu name %d ('%s')\n",
+			 i, (ssize_t)(rel->r_info >> 32), (size_t)sym->st_value,
+			 (size_t)rel->r_offset, sym->st_name, name);
+
+		for (j = 0; j < obj->nr_maps; j++) {
+			map = &obj->maps[j];
+			if (map->sec_idx != obj->efile.btf_maps_shndx)
+				continue;
+
+			vi = btf_var_secinfos(sec) + map->btf_var_idx;
+			if (vi->offset <= rel->r_offset &&
+			    rel->r_offset + bpf_ptr_sz <= vi->offset + vi->size)
+				break;
+		}
+		if (j == obj->nr_maps) {
+			pr_warn(".maps relo #%d: cannot find map '%s' at rel->r_offset %zu\n",
+				i, name, (size_t)rel->r_offset);
+			return -EINVAL;
+		}
+
+		is_map_in_map = bpf_map_type__is_map_in_map(map->def.type);
+		is_prog_array = map->def.type == BPF_MAP_TYPE_PROG_ARRAY;
+		type = is_map_in_map ? "map" : "prog";
+		if (is_map_in_map) {
+			if (sym->st_shndx != obj->efile.btf_maps_shndx) {
+				pr_warn(".maps relo #%d: '%s' isn't a BTF-defined map\n",
+					i, name);
+				return -LIBBPF_ERRNO__RELOC;
+			}
+			if (map->def.type == BPF_MAP_TYPE_HASH_OF_MAPS &&
+			    map->def.key_size != sizeof(int)) {
+				pr_warn(".maps relo #%d: hash-of-maps '%s' should have key size %zu.\n",
+					i, map->name, sizeof(int));
+				return -EINVAL;
+			}
+			targ_map = bpf_object__find_map_by_name(obj, name);
+			if (!targ_map) {
+				pr_warn(".maps relo #%d: '%s' isn't a valid map reference\n",
+					i, name);
+				return -ESRCH;
+			}
+		} else if (is_prog_array) {
+			targ_prog = bpf_object__find_program_by_name(obj, name);
+			if (!targ_prog) {
+				pr_warn(".maps relo #%d: '%s' isn't a valid program reference\n",
+					i, name);
+				return -ESRCH;
+			}
+			if (targ_prog->sec_idx != sym->st_shndx ||
+			    targ_prog->sec_insn_off * 8 != sym->st_value ||
+			    prog_is_subprog(obj, targ_prog)) {
+				pr_warn(".maps relo #%d: '%s' isn't an entry-point program\n",
+					i, name);
+				return -LIBBPF_ERRNO__RELOC;
+			}
+		} else {
+			return -EINVAL;
+		}
+
+		var = btf__type_by_id(obj->btf, vi->type);
+		def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
+		if (btf_vlen(def) == 0)
+			return -EINVAL;
+		member = btf_members(def) + btf_vlen(def) - 1;
+		mname = btf__name_by_offset(obj->btf, member->name_off);
+		if (strcmp(mname, "values"))
+			return -EINVAL;
+
+		moff = btf_member_bit_offset(def, btf_vlen(def) - 1) / 8;
+		if (rel->r_offset - vi->offset < moff)
+			return -EINVAL;
+
+		moff = rel->r_offset - vi->offset - moff;
+		/* here we use BPF pointer size, which is always 64 bit, as we
+		 * are parsing ELF that was built for BPF target
+		 */
+		if (moff % bpf_ptr_sz)
+			return -EINVAL;
+		moff /= bpf_ptr_sz;
+		if (moff >= map->init_slots_sz) {
+			new_sz = moff + 1;
+			tmp = libbpf_reallocarray(map->init_slots, new_sz, host_ptr_sz);
+			if (!tmp)
+				return -ENOMEM;
+			map->init_slots = tmp;
+			memset(map->init_slots + map->init_slots_sz, 0,
+			       (new_sz - map->init_slots_sz) * host_ptr_sz);
+			map->init_slots_sz = new_sz;
+		}
+		map->init_slots[moff] = is_map_in_map ? (void *)targ_map : (void *)targ_prog;
+
+		pr_debug(".maps relo #%d: map '%s' slot [%d] points to %s '%s'\n",
+			 i, map->name, moff, type, name);
+	}
+
+	return 0;
+}
+
+static int bpf_object__collect_relos(struct bpf_object *obj)
+{
+	int i, err;
+
+	for (i = 0; i < obj->efile.sec_cnt; i++) {
+		struct elf_sec_desc *sec_desc = &obj->efile.secs[i];
+		Elf64_Shdr *shdr;
+		Elf_Data *data;
+		int idx;
+
+		if (sec_desc->sec_type != SEC_RELO)
+			continue;
+
+		shdr = sec_desc->shdr;
+		data = sec_desc->data;
+		idx = shdr->sh_info;
+
+		if (shdr->sh_type != SHT_REL) {
+			pr_warn("internal error at %d\n", __LINE__);
+			return -LIBBPF_ERRNO__INTERNAL;
+		}
+
+		if (idx == obj->efile.st_ops_shndx)
+			err = bpf_object__collect_st_ops_relos(obj, shdr, data);
+		else if (idx == obj->efile.btf_maps_shndx)
+			err = bpf_object__collect_map_relos(obj, shdr, data);
+		else
+			err = bpf_object__collect_prog_relos(obj, shdr, data);
+		if (err)
+			return err;
+	}
+
+	bpf_object__sort_relos(obj);
+	return 0;
+}
+
+static bool insn_is_helper_call(struct bpf_insn *insn, enum bpf_func_id *func_id)
+{
+	if (BPF_CLASS(insn->code) == BPF_JMP &&
+	    BPF_OP(insn->code) == BPF_CALL &&
+	    BPF_SRC(insn->code) == BPF_K &&
+	    insn->src_reg == 0 &&
+	    insn->dst_reg == 0) {
+		    *func_id = insn->imm;
+		    return true;
+	}
+	return false;
+}
+
+static int bpf_object__sanitize_prog(struct bpf_object *obj, struct bpf_program *prog)
+{
+	struct bpf_insn *insn = prog->insns;
+	enum bpf_func_id func_id;
+	int i;
+
+	if (obj->gen_loader)
+		return 0;
+
+	for (i = 0; i < prog->insns_cnt; i++, insn++) {
+		if (!insn_is_helper_call(insn, &func_id))
+			continue;
+
+		/* on kernels that don't yet support
+		 * bpf_probe_read_{kernel,user}[_str] helpers, fall back
+		 * to bpf_probe_read() which works well for old kernels
+		 */
+		switch (func_id) {
+		case BPF_FUNC_probe_read_kernel:
+		case BPF_FUNC_probe_read_user:
+			if (!kernel_supports(obj, FEAT_PROBE_READ_KERN))
+				insn->imm = BPF_FUNC_probe_read;
+			break;
+		case BPF_FUNC_probe_read_kernel_str:
+		case BPF_FUNC_probe_read_user_str:
+			if (!kernel_supports(obj, FEAT_PROBE_READ_KERN))
+				insn->imm = BPF_FUNC_probe_read_str;
+			break;
+		default:
+			break;
+		}
+	}
+	return 0;
+}
+
+static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attach_name,
+				     int *btf_obj_fd, int *btf_type_id);
+
+/* this is called as prog->sec_def->prog_prepare_load_fn for libbpf-supported sec_defs */
+static int libbpf_prepare_prog_load(struct bpf_program *prog,
+				    struct bpf_prog_load_opts *opts, long cookie)
+{
+	enum sec_def_flags def = cookie;
+
+	/* old kernels might not support specifying expected_attach_type */
+	if ((def & SEC_EXP_ATTACH_OPT) && !kernel_supports(prog->obj, FEAT_EXP_ATTACH_TYPE))
+		opts->expected_attach_type = 0;
+
+	if (def & SEC_SLEEPABLE)
+		opts->prog_flags |= BPF_F_SLEEPABLE;
+
+	if (prog->type == BPF_PROG_TYPE_XDP && (def & SEC_XDP_FRAGS))
+		opts->prog_flags |= BPF_F_XDP_HAS_FRAGS;
+
+	if ((def & SEC_ATTACH_BTF) && !prog->attach_btf_id) {
+		int btf_obj_fd = 0, btf_type_id = 0, err;
+		const char *attach_name;
+
+		attach_name = strchr(prog->sec_name, '/');
+		if (!attach_name) {
+			/* if BPF program is annotated with just SEC("fentry")
+			 * (or similar) without declaratively specifying
+			 * target, then it is expected that target will be
+			 * specified with bpf_program__set_attach_target() at
+			 * runtime before BPF object load step. If not, then
+			 * there is nothing to load into the kernel as BPF
+			 * verifier won't be able to validate BPF program
+			 * correctness anyways.
+			 */
+			pr_warn("prog '%s': no BTF-based attach target is specified, use bpf_program__set_attach_target()\n",
+				prog->name);
+			return -EINVAL;
+		}
+		attach_name++; /* skip over / */
+
+		err = libbpf_find_attach_btf_id(prog, attach_name, &btf_obj_fd, &btf_type_id);
+		if (err)
+			return err;
+
+		/* cache resolved BTF FD and BTF type ID in the prog */
+		prog->attach_btf_obj_fd = btf_obj_fd;
+		prog->attach_btf_id = btf_type_id;
+
+		/* but by now libbpf common logic is not utilizing
+		 * prog->atach_btf_obj_fd/prog->attach_btf_id anymore because
+		 * this callback is called after opts were populated by
+		 * libbpf, so this callback has to update opts explicitly here
+		 */
+		opts->attach_btf_obj_fd = btf_obj_fd;
+		opts->attach_btf_id = btf_type_id;
+	}
+	return 0;
+}
+
+static void fixup_verifier_log(struct bpf_program *prog, char *buf, size_t buf_sz);
+
+static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog,
+				struct bpf_insn *insns, int insns_cnt,
+				const char *license, __u32 kern_version, int *prog_fd)
+{
+	LIBBPF_OPTS(bpf_prog_load_opts, load_attr);
+	const char *prog_name = NULL;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	size_t log_buf_size = 0;
+	char *log_buf = NULL, *tmp;
+	int btf_fd, ret, err;
+	bool own_log_buf = true;
+	__u32 log_level = prog->log_level;
+
+	if (prog->type == BPF_PROG_TYPE_UNSPEC) {
+		/*
+		 * The program type must be set.  Most likely we couldn't find a proper
+		 * section definition at load time, and thus we didn't infer the type.
+		 */
+		pr_warn("prog '%s': missing BPF prog type, check ELF section name '%s'\n",
+			prog->name, prog->sec_name);
+		return -EINVAL;
+	}
+
+	if (!insns || !insns_cnt)
+		return -EINVAL;
+
+	load_attr.expected_attach_type = prog->expected_attach_type;
+	if (kernel_supports(obj, FEAT_PROG_NAME))
+		prog_name = prog->name;
+	load_attr.attach_prog_fd = prog->attach_prog_fd;
+	load_attr.attach_btf_obj_fd = prog->attach_btf_obj_fd;
+	load_attr.attach_btf_id = prog->attach_btf_id;
+	load_attr.kern_version = kern_version;
+	load_attr.prog_ifindex = prog->prog_ifindex;
+
+	/* specify func_info/line_info only if kernel supports them */
+	btf_fd = bpf_object__btf_fd(obj);
+	if (btf_fd >= 0 && kernel_supports(obj, FEAT_BTF_FUNC)) {
+		load_attr.prog_btf_fd = btf_fd;
+		load_attr.func_info = prog->func_info;
+		load_attr.func_info_rec_size = prog->func_info_rec_size;
+		load_attr.func_info_cnt = prog->func_info_cnt;
+		load_attr.line_info = prog->line_info;
+		load_attr.line_info_rec_size = prog->line_info_rec_size;
+		load_attr.line_info_cnt = prog->line_info_cnt;
+	}
+	load_attr.log_level = log_level;
+	load_attr.prog_flags = prog->prog_flags;
+	load_attr.fd_array = obj->fd_array;
+
+	/* adjust load_attr if sec_def provides custom preload callback */
+	if (prog->sec_def && prog->sec_def->prog_prepare_load_fn) {
+		err = prog->sec_def->prog_prepare_load_fn(prog, &load_attr, prog->sec_def->cookie);
+		if (err < 0) {
+			pr_warn("prog '%s': failed to prepare load attributes: %d\n",
+				prog->name, err);
+			return err;
+		}
+		insns = prog->insns;
+		insns_cnt = prog->insns_cnt;
+	}
+
+	if (obj->gen_loader) {
+		bpf_gen__prog_load(obj->gen_loader, prog->type, prog->name,
+				   license, insns, insns_cnt, &load_attr,
+				   prog - obj->programs);
+		*prog_fd = -1;
+		return 0;
+	}
+
+retry_load:
+	/* if log_level is zero, we don't request logs initially even if
+	 * custom log_buf is specified; if the program load fails, then we'll
+	 * bump log_level to 1 and use either custom log_buf or we'll allocate
+	 * our own and retry the load to get details on what failed
+	 */
+	if (log_level) {
+		if (prog->log_buf) {
+			log_buf = prog->log_buf;
+			log_buf_size = prog->log_size;
+			own_log_buf = false;
+		} else if (obj->log_buf) {
+			log_buf = obj->log_buf;
+			log_buf_size = obj->log_size;
+			own_log_buf = false;
+		} else {
+			log_buf_size = max((size_t)BPF_LOG_BUF_SIZE, log_buf_size * 2);
+			tmp = realloc(log_buf, log_buf_size);
+			if (!tmp) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			log_buf = tmp;
+			log_buf[0] = '\0';
+			own_log_buf = true;
+		}
+	}
+
+	load_attr.log_buf = log_buf;
+	load_attr.log_size = log_buf_size;
+	load_attr.log_level = log_level;
+
+	ret = bpf_prog_load(prog->type, prog_name, license, insns, insns_cnt, &load_attr);
+	if (ret >= 0) {
+		if (log_level && own_log_buf) {
+			pr_debug("prog '%s': -- BEGIN PROG LOAD LOG --\n%s-- END PROG LOAD LOG --\n",
+				 prog->name, log_buf);
+		}
+
+		if (obj->has_rodata && kernel_supports(obj, FEAT_PROG_BIND_MAP)) {
+			struct bpf_map *map;
+			int i;
+
+			for (i = 0; i < obj->nr_maps; i++) {
+				map = &prog->obj->maps[i];
+				if (map->libbpf_type != LIBBPF_MAP_RODATA)
+					continue;
+
+				if (bpf_prog_bind_map(ret, bpf_map__fd(map), NULL)) {
+					cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+					pr_warn("prog '%s': failed to bind map '%s': %s\n",
+						prog->name, map->real_name, cp);
+					/* Don't fail hard if can't bind rodata. */
+				}
+			}
+		}
+
+		*prog_fd = ret;
+		ret = 0;
+		goto out;
+	}
+
+	if (log_level == 0) {
+		log_level = 1;
+		goto retry_load;
+	}
+	/* On ENOSPC, increase log buffer size and retry, unless custom
+	 * log_buf is specified.
+	 * Be careful to not overflow u32, though. Kernel's log buf size limit
+	 * isn't part of UAPI so it can always be bumped to full 4GB. So don't
+	 * multiply by 2 unless we are sure we'll fit within 32 bits.
+	 * Currently, we'll get -EINVAL when we reach (UINT_MAX >> 2).
+	 */
+	if (own_log_buf && errno == ENOSPC && log_buf_size <= UINT_MAX / 2)
+		goto retry_load;
+
+	ret = -errno;
+
+	/* post-process verifier log to improve error descriptions */
+	fixup_verifier_log(prog, log_buf, log_buf_size);
+
+	cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+	pr_warn("prog '%s': BPF program load failed: %s\n", prog->name, cp);
+	pr_perm_msg(ret);
+
+	if (own_log_buf && log_buf && log_buf[0] != '\0') {
+		pr_warn("prog '%s': -- BEGIN PROG LOAD LOG --\n%s-- END PROG LOAD LOG --\n",
+			prog->name, log_buf);
+	}
+
+out:
+	if (own_log_buf)
+		free(log_buf);
+	return ret;
+}
+
+static char *find_prev_line(char *buf, char *cur)
+{
+	char *p;
+
+	if (cur == buf) /* end of a log buf */
+		return NULL;
+
+	p = cur - 1;
+	while (p - 1 >= buf && *(p - 1) != '\n')
+		p--;
+
+	return p;
+}
+
+static void patch_log(char *buf, size_t buf_sz, size_t log_sz,
+		      char *orig, size_t orig_sz, const char *patch)
+{
+	/* size of the remaining log content to the right from the to-be-replaced part */
+	size_t rem_sz = (buf + log_sz) - (orig + orig_sz);
+	size_t patch_sz = strlen(patch);
+
+	if (patch_sz != orig_sz) {
+		/* If patch line(s) are longer than original piece of verifier log,
+		 * shift log contents by (patch_sz - orig_sz) bytes to the right
+		 * starting from after to-be-replaced part of the log.
+		 *
+		 * If patch line(s) are shorter than original piece of verifier log,
+		 * shift log contents by (orig_sz - patch_sz) bytes to the left
+		 * starting from after to-be-replaced part of the log
+		 *
+		 * We need to be careful about not overflowing available
+		 * buf_sz capacity. If that's the case, we'll truncate the end
+		 * of the original log, as necessary.
+		 */
+		if (patch_sz > orig_sz) {
+			if (orig + patch_sz >= buf + buf_sz) {
+				/* patch is big enough to cover remaining space completely */
+				patch_sz -= (orig + patch_sz) - (buf + buf_sz) + 1;
+				rem_sz = 0;
+			} else if (patch_sz - orig_sz > buf_sz - log_sz) {
+				/* patch causes part of remaining log to be truncated */
+				rem_sz -= (patch_sz - orig_sz) - (buf_sz - log_sz);
+			}
+		}
+		/* shift remaining log to the right by calculated amount */
+		memmove(orig + patch_sz, orig + orig_sz, rem_sz);
+	}
+
+	memcpy(orig, patch, patch_sz);
+}
+
+static void fixup_log_failed_core_relo(struct bpf_program *prog,
+				       char *buf, size_t buf_sz, size_t log_sz,
+				       char *line1, char *line2, char *line3)
+{
+	/* Expected log for failed and not properly guarded CO-RE relocation:
+	 * line1 -> 123: (85) call unknown#195896080
+	 * line2 -> invalid func unknown#195896080
+	 * line3 -> <anything else or end of buffer>
+	 *
+	 * "123" is the index of the instruction that was poisoned. We extract
+	 * instruction index to find corresponding CO-RE relocation and
+	 * replace this part of the log with more relevant information about
+	 * failed CO-RE relocation.
+	 */
+	const struct bpf_core_relo *relo;
+	struct bpf_core_spec spec;
+	char patch[512], spec_buf[256];
+	int insn_idx, err, spec_len;
+
+	if (sscanf(line1, "%d: (%*d) call unknown#195896080\n", &insn_idx) != 1)
+		return;
+
+	relo = find_relo_core(prog, insn_idx);
+	if (!relo)
+		return;
+
+	err = bpf_core_parse_spec(prog->name, prog->obj->btf, relo, &spec);
+	if (err)
+		return;
+
+	spec_len = bpf_core_format_spec(spec_buf, sizeof(spec_buf), &spec);
+	snprintf(patch, sizeof(patch),
+		 "%d: <invalid CO-RE relocation>\n"
+		 "failed to resolve CO-RE relocation %s%s\n",
+		 insn_idx, spec_buf, spec_len >= sizeof(spec_buf) ? "..." : "");
+
+	patch_log(buf, buf_sz, log_sz, line1, line3 - line1, patch);
+}
+
+static void fixup_log_missing_map_load(struct bpf_program *prog,
+				       char *buf, size_t buf_sz, size_t log_sz,
+				       char *line1, char *line2, char *line3)
+{
+	/* Expected log for failed and not properly guarded CO-RE relocation:
+	 * line1 -> 123: (85) call unknown#2001000345
+	 * line2 -> invalid func unknown#2001000345
+	 * line3 -> <anything else or end of buffer>
+	 *
+	 * "123" is the index of the instruction that was poisoned.
+	 * "345" in "2001000345" are map index in obj->maps to fetch map name.
+	 */
+	struct bpf_object *obj = prog->obj;
+	const struct bpf_map *map;
+	int insn_idx, map_idx;
+	char patch[128];
+
+	if (sscanf(line1, "%d: (%*d) call unknown#%d\n", &insn_idx, &map_idx) != 2)
+		return;
+
+	map_idx -= MAP_LDIMM64_POISON_BASE;
+	if (map_idx < 0 || map_idx >= obj->nr_maps)
+		return;
+	map = &obj->maps[map_idx];
+
+	snprintf(patch, sizeof(patch),
+		 "%d: <invalid BPF map reference>\n"
+		 "BPF map '%s' is referenced but wasn't created\n",
+		 insn_idx, map->name);
+
+	patch_log(buf, buf_sz, log_sz, line1, line3 - line1, patch);
+}
+
+static void fixup_verifier_log(struct bpf_program *prog, char *buf, size_t buf_sz)
+{
+	/* look for familiar error patterns in last N lines of the log */
+	const size_t max_last_line_cnt = 10;
+	char *prev_line, *cur_line, *next_line;
+	size_t log_sz;
+	int i;
+
+	if (!buf)
+		return;
+
+	log_sz = strlen(buf) + 1;
+	next_line = buf + log_sz - 1;
+
+	for (i = 0; i < max_last_line_cnt; i++, next_line = cur_line) {
+		cur_line = find_prev_line(buf, next_line);
+		if (!cur_line)
+			return;
+
+		/* failed CO-RE relocation case */
+		if (str_has_pfx(cur_line, "invalid func unknown#195896080\n")) {
+			prev_line = find_prev_line(buf, cur_line);
+			if (!prev_line)
+				continue;
+
+			fixup_log_failed_core_relo(prog, buf, buf_sz, log_sz,
+						   prev_line, cur_line, next_line);
+			return;
+		} else if (str_has_pfx(cur_line, "invalid func unknown#"MAP_LDIMM64_POISON_PFX)) {
+			prev_line = find_prev_line(buf, cur_line);
+			if (!prev_line)
+				continue;
+
+			fixup_log_missing_map_load(prog, buf, buf_sz, log_sz,
+						   prev_line, cur_line, next_line);
+			return;
+		}
+	}
+}
+
+static int bpf_program_record_relos(struct bpf_program *prog)
+{
+	struct bpf_object *obj = prog->obj;
+	int i;
+
+	for (i = 0; i < prog->nr_reloc; i++) {
+		struct reloc_desc *relo = &prog->reloc_desc[i];
+		struct extern_desc *ext = &obj->externs[relo->sym_off];
+
+		switch (relo->type) {
+		case RELO_EXTERN_VAR:
+			if (ext->type != EXT_KSYM)
+				continue;
+			bpf_gen__record_extern(obj->gen_loader, ext->name,
+					       ext->is_weak, !ext->ksym.type_id,
+					       BTF_KIND_VAR, relo->insn_idx);
+			break;
+		case RELO_EXTERN_FUNC:
+			bpf_gen__record_extern(obj->gen_loader, ext->name,
+					       ext->is_weak, false, BTF_KIND_FUNC,
+					       relo->insn_idx);
+			break;
+		case RELO_CORE: {
+			struct bpf_core_relo cr = {
+				.insn_off = relo->insn_idx * 8,
+				.type_id = relo->core_relo->type_id,
+				.access_str_off = relo->core_relo->access_str_off,
+				.kind = relo->core_relo->kind,
+			};
+
+			bpf_gen__record_relo_core(obj->gen_loader, &cr);
+			break;
+		}
+		default:
+			continue;
+		}
+	}
+	return 0;
+}
+
+static int
+bpf_object__load_progs(struct bpf_object *obj, int log_level)
+{
+	struct bpf_program *prog;
+	size_t i;
+	int err;
+
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		err = bpf_object__sanitize_prog(obj, prog);
+		if (err)
+			return err;
+	}
+
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		if (prog_is_subprog(obj, prog))
+			continue;
+		if (!prog->autoload) {
+			pr_debug("prog '%s': skipped loading\n", prog->name);
+			continue;
+		}
+		prog->log_level |= log_level;
+
+		if (obj->gen_loader)
+			bpf_program_record_relos(prog);
+
+		err = bpf_object_load_prog(obj, prog, prog->insns, prog->insns_cnt,
+					   obj->license, obj->kern_version, &prog->fd);
+		if (err) {
+			pr_warn("prog '%s': failed to load: %d\n", prog->name, err);
+			return err;
+		}
+	}
+
+	bpf_object__free_relocs(obj);
+	return 0;
+}
+
+static const struct bpf_sec_def *find_sec_def(const char *sec_name);
+
+static int bpf_object_init_progs(struct bpf_object *obj, const struct bpf_object_open_opts *opts)
+{
+	struct bpf_program *prog;
+	int err;
+
+	bpf_object__for_each_program(prog, obj) {
+		prog->sec_def = find_sec_def(prog->sec_name);
+		if (!prog->sec_def) {
+			/* couldn't guess, but user might manually specify */
+			pr_debug("prog '%s': unrecognized ELF section name '%s'\n",
+				prog->name, prog->sec_name);
+			continue;
+		}
+
+		prog->type = prog->sec_def->prog_type;
+		prog->expected_attach_type = prog->sec_def->expected_attach_type;
+
+		/* sec_def can have custom callback which should be called
+		 * after bpf_program is initialized to adjust its properties
+		 */
+		if (prog->sec_def->prog_setup_fn) {
+			err = prog->sec_def->prog_setup_fn(prog, prog->sec_def->cookie);
+			if (err < 0) {
+				pr_warn("prog '%s': failed to initialize: %d\n",
+					prog->name, err);
+				return err;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static struct bpf_object *bpf_object_open(const char *path, const void *obj_buf, size_t obj_buf_sz,
+					  const struct bpf_object_open_opts *opts)
+{
+	const char *obj_name, *kconfig, *btf_tmp_path;
+	struct bpf_object *obj;
+	char tmp_name[64];
+	int err;
+	char *log_buf;
+	size_t log_size;
+	__u32 log_level;
+
+	if (elf_version(EV_CURRENT) == EV_NONE) {
+		pr_warn("failed to init libelf for %s\n",
+			path ? : "(mem buf)");
+		return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
+	}
+
+	if (!OPTS_VALID(opts, bpf_object_open_opts))
+		return ERR_PTR(-EINVAL);
+
+	obj_name = OPTS_GET(opts, object_name, NULL);
+	if (obj_buf) {
+		if (!obj_name) {
+			snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
+				 (unsigned long)obj_buf,
+				 (unsigned long)obj_buf_sz);
+			obj_name = tmp_name;
+		}
+		path = obj_name;
+		pr_debug("loading object '%s' from buffer\n", obj_name);
+	}
+
+	log_buf = OPTS_GET(opts, kernel_log_buf, NULL);
+	log_size = OPTS_GET(opts, kernel_log_size, 0);
+	log_level = OPTS_GET(opts, kernel_log_level, 0);
+	if (log_size > UINT_MAX)
+		return ERR_PTR(-EINVAL);
+	if (log_size && !log_buf)
+		return ERR_PTR(-EINVAL);
+
+	obj = bpf_object__new(path, obj_buf, obj_buf_sz, obj_name);
+	if (IS_ERR(obj))
+		return obj;
+
+	obj->log_buf = log_buf;
+	obj->log_size = log_size;
+	obj->log_level = log_level;
+
+	btf_tmp_path = OPTS_GET(opts, btf_custom_path, NULL);
+	if (btf_tmp_path) {
+		if (strlen(btf_tmp_path) >= PATH_MAX) {
+			err = -ENAMETOOLONG;
+			goto out;
+		}
+		obj->btf_custom_path = strdup(btf_tmp_path);
+		if (!obj->btf_custom_path) {
+			err = -ENOMEM;
+			goto out;
+		}
+	}
+
+	kconfig = OPTS_GET(opts, kconfig, NULL);
+	if (kconfig) {
+		obj->kconfig = strdup(kconfig);
+		if (!obj->kconfig) {
+			err = -ENOMEM;
+			goto out;
+		}
+	}
+
+	err = bpf_object__elf_init(obj);
+	err = err ? : bpf_object__check_endianness(obj);
+	err = err ? : bpf_object__elf_collect(obj);
+	err = err ? : bpf_object__collect_externs(obj);
+	err = err ? : bpf_object__finalize_btf(obj);
+	err = err ? : bpf_object__init_maps(obj, opts);
+	err = err ? : bpf_object_init_progs(obj, opts);
+	err = err ? : bpf_object__collect_relos(obj);
+	if (err)
+		goto out;
+
+	bpf_object__elf_finish(obj);
+
+	return obj;
+out:
+	bpf_object__close(obj);
+	return ERR_PTR(err);
+}
+
+struct bpf_object *
+bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts)
+{
+	if (!path)
+		return libbpf_err_ptr(-EINVAL);
+
+	pr_debug("loading %s\n", path);
+
+	return libbpf_ptr(bpf_object_open(path, NULL, 0, opts));
+}
+
+struct bpf_object *bpf_object__open(const char *path)
+{
+	return bpf_object__open_file(path, NULL);
+}
+
+struct bpf_object *
+bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
+		     const struct bpf_object_open_opts *opts)
+{
+	if (!obj_buf || obj_buf_sz == 0)
+		return libbpf_err_ptr(-EINVAL);
+
+	return libbpf_ptr(bpf_object_open(NULL, obj_buf, obj_buf_sz, opts));
+}
+
+static int bpf_object_unload(struct bpf_object *obj)
+{
+	size_t i;
+
+	if (!obj)
+		return libbpf_err(-EINVAL);
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		zclose(obj->maps[i].fd);
+		if (obj->maps[i].st_ops)
+			zfree(&obj->maps[i].st_ops->kern_vdata);
+	}
+
+	for (i = 0; i < obj->nr_programs; i++)
+		bpf_program__unload(&obj->programs[i]);
+
+	return 0;
+}
+
+static int bpf_object__sanitize_maps(struct bpf_object *obj)
+{
+	struct bpf_map *m;
+
+	bpf_object__for_each_map(m, obj) {
+		if (!bpf_map__is_internal(m))
+			continue;
+		if (!kernel_supports(obj, FEAT_ARRAY_MMAP))
+			m->def.map_flags ^= BPF_F_MMAPABLE;
+	}
+
+	return 0;
+}
+
+int libbpf_kallsyms_parse(kallsyms_cb_t cb, void *ctx)
+{
+	char sym_type, sym_name[500];
+	unsigned long long sym_addr;
+	int ret, err = 0;
+	FILE *f;
+
+	f = fopen("/proc/kallsyms", "r");
+	if (!f) {
+		err = -errno;
+		pr_warn("failed to open /proc/kallsyms: %d\n", err);
+		return err;
+	}
+
+	while (true) {
+		ret = fscanf(f, "%llx %c %499s%*[^\n]\n",
+			     &sym_addr, &sym_type, sym_name);
+		if (ret == EOF && feof(f))
+			break;
+		if (ret != 3) {
+			pr_warn("failed to read kallsyms entry: %d\n", ret);
+			err = -EINVAL;
+			break;
+		}
+
+		err = cb(sym_addr, sym_type, sym_name, ctx);
+		if (err)
+			break;
+	}
+
+	fclose(f);
+	return err;
+}
+
+static int kallsyms_cb(unsigned long long sym_addr, char sym_type,
+		       const char *sym_name, void *ctx)
+{
+	struct bpf_object *obj = ctx;
+	const struct btf_type *t;
+	struct extern_desc *ext;
+
+	ext = find_extern_by_name(obj, sym_name);
+	if (!ext || ext->type != EXT_KSYM)
+		return 0;
+
+	t = btf__type_by_id(obj->btf, ext->btf_id);
+	if (!btf_is_var(t))
+		return 0;
+
+	if (ext->is_set && ext->ksym.addr != sym_addr) {
+		pr_warn("extern (ksym) '%s': resolution is ambiguous: 0x%llx or 0x%llx\n",
+			sym_name, ext->ksym.addr, sym_addr);
+		return -EINVAL;
+	}
+	if (!ext->is_set) {
+		ext->is_set = true;
+		ext->ksym.addr = sym_addr;
+		pr_debug("extern (ksym) '%s': set to 0x%llx\n", sym_name, sym_addr);
+	}
+	return 0;
+}
+
+static int bpf_object__read_kallsyms_file(struct bpf_object *obj)
+{
+	return libbpf_kallsyms_parse(kallsyms_cb, obj);
+}
+
+static int find_ksym_btf_id(struct bpf_object *obj, const char *ksym_name,
+			    __u16 kind, struct btf **res_btf,
+			    struct module_btf **res_mod_btf)
+{
+	struct module_btf *mod_btf;
+	struct btf *btf;
+	int i, id, err;
+
+	btf = obj->btf_vmlinux;
+	mod_btf = NULL;
+	id = btf__find_by_name_kind(btf, ksym_name, kind);
+
+	if (id == -ENOENT) {
+		err = load_module_btfs(obj);
+		if (err)
+			return err;
+
+		for (i = 0; i < obj->btf_module_cnt; i++) {
+			/* we assume module_btf's BTF FD is always >0 */
+			mod_btf = &obj->btf_modules[i];
+			btf = mod_btf->btf;
+			id = btf__find_by_name_kind_own(btf, ksym_name, kind);
+			if (id != -ENOENT)
+				break;
+		}
+	}
+	if (id <= 0)
+		return -ESRCH;
+
+	*res_btf = btf;
+	*res_mod_btf = mod_btf;
+	return id;
+}
+
+static int bpf_object__resolve_ksym_var_btf_id(struct bpf_object *obj,
+					       struct extern_desc *ext)
+{
+	const struct btf_type *targ_var, *targ_type;
+	__u32 targ_type_id, local_type_id;
+	struct module_btf *mod_btf = NULL;
+	const char *targ_var_name;
+	struct btf *btf = NULL;
+	int id, err;
+
+	id = find_ksym_btf_id(obj, ext->name, BTF_KIND_VAR, &btf, &mod_btf);
+	if (id < 0) {
+		if (id == -ESRCH && ext->is_weak)
+			return 0;
+		pr_warn("extern (var ksym) '%s': not found in kernel BTF\n",
+			ext->name);
+		return id;
+	}
+
+	/* find local type_id */
+	local_type_id = ext->ksym.type_id;
+
+	/* find target type_id */
+	targ_var = btf__type_by_id(btf, id);
+	targ_var_name = btf__name_by_offset(btf, targ_var->name_off);
+	targ_type = skip_mods_and_typedefs(btf, targ_var->type, &targ_type_id);
+
+	err = bpf_core_types_are_compat(obj->btf, local_type_id,
+					btf, targ_type_id);
+	if (err <= 0) {
+		const struct btf_type *local_type;
+		const char *targ_name, *local_name;
+
+		local_type = btf__type_by_id(obj->btf, local_type_id);
+		local_name = btf__name_by_offset(obj->btf, local_type->name_off);
+		targ_name = btf__name_by_offset(btf, targ_type->name_off);
+
+		pr_warn("extern (var ksym) '%s': incompatible types, expected [%d] %s %s, but kernel has [%d] %s %s\n",
+			ext->name, local_type_id,
+			btf_kind_str(local_type), local_name, targ_type_id,
+			btf_kind_str(targ_type), targ_name);
+		return -EINVAL;
+	}
+
+	ext->is_set = true;
+	ext->ksym.kernel_btf_obj_fd = mod_btf ? mod_btf->fd : 0;
+	ext->ksym.kernel_btf_id = id;
+	pr_debug("extern (var ksym) '%s': resolved to [%d] %s %s\n",
+		 ext->name, id, btf_kind_str(targ_var), targ_var_name);
+
+	return 0;
+}
+
+static int bpf_object__resolve_ksym_func_btf_id(struct bpf_object *obj,
+						struct extern_desc *ext)
+{
+	int local_func_proto_id, kfunc_proto_id, kfunc_id;
+	struct module_btf *mod_btf = NULL;
+	const struct btf_type *kern_func;
+	struct btf *kern_btf = NULL;
+	int ret;
+
+	local_func_proto_id = ext->ksym.type_id;
+
+	kfunc_id = find_ksym_btf_id(obj, ext->name, BTF_KIND_FUNC, &kern_btf, &mod_btf);
+	if (kfunc_id < 0) {
+		if (kfunc_id == -ESRCH && ext->is_weak)
+			return 0;
+		pr_warn("extern (func ksym) '%s': not found in kernel or module BTFs\n",
+			ext->name);
+		return kfunc_id;
+	}
+
+	kern_func = btf__type_by_id(kern_btf, kfunc_id);
+	kfunc_proto_id = kern_func->type;
+
+	ret = bpf_core_types_are_compat(obj->btf, local_func_proto_id,
+					kern_btf, kfunc_proto_id);
+	if (ret <= 0) {
+		pr_warn("extern (func ksym) '%s': func_proto [%d] incompatible with kernel [%d]\n",
+			ext->name, local_func_proto_id, kfunc_proto_id);
+		return -EINVAL;
+	}
+
+	/* set index for module BTF fd in fd_array, if unset */
+	if (mod_btf && !mod_btf->fd_array_idx) {
+		/* insn->off is s16 */
+		if (obj->fd_array_cnt == INT16_MAX) {
+			pr_warn("extern (func ksym) '%s': module BTF fd index %d too big to fit in bpf_insn offset\n",
+				ext->name, mod_btf->fd_array_idx);
+			return -E2BIG;
+		}
+		/* Cannot use index 0 for module BTF fd */
+		if (!obj->fd_array_cnt)
+			obj->fd_array_cnt = 1;
+
+		ret = libbpf_ensure_mem((void **)&obj->fd_array, &obj->fd_array_cap, sizeof(int),
+					obj->fd_array_cnt + 1);
+		if (ret)
+			return ret;
+		mod_btf->fd_array_idx = obj->fd_array_cnt;
+		/* we assume module BTF FD is always >0 */
+		obj->fd_array[obj->fd_array_cnt++] = mod_btf->fd;
+	}
+
+	ext->is_set = true;
+	ext->ksym.kernel_btf_id = kfunc_id;
+	ext->ksym.btf_fd_idx = mod_btf ? mod_btf->fd_array_idx : 0;
+	pr_debug("extern (func ksym) '%s': resolved to kernel [%d]\n",
+		 ext->name, kfunc_id);
+
+	return 0;
+}
+
+static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj)
+{
+	const struct btf_type *t;
+	struct extern_desc *ext;
+	int i, err;
+
+	for (i = 0; i < obj->nr_extern; i++) {
+		ext = &obj->externs[i];
+		if (ext->type != EXT_KSYM || !ext->ksym.type_id)
+			continue;
+
+		if (obj->gen_loader) {
+			ext->is_set = true;
+			ext->ksym.kernel_btf_obj_fd = 0;
+			ext->ksym.kernel_btf_id = 0;
+			continue;
+		}
+		t = btf__type_by_id(obj->btf, ext->btf_id);
+		if (btf_is_var(t))
+			err = bpf_object__resolve_ksym_var_btf_id(obj, ext);
+		else
+			err = bpf_object__resolve_ksym_func_btf_id(obj, ext);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int bpf_object__resolve_externs(struct bpf_object *obj,
+				       const char *extra_kconfig)
+{
+	bool need_config = false, need_kallsyms = false;
+	bool need_vmlinux_btf = false;
+	struct extern_desc *ext;
+	void *kcfg_data = NULL;
+	int err, i;
+
+	if (obj->nr_extern == 0)
+		return 0;
+
+	if (obj->kconfig_map_idx >= 0)
+		kcfg_data = obj->maps[obj->kconfig_map_idx].mmaped;
+
+	for (i = 0; i < obj->nr_extern; i++) {
+		ext = &obj->externs[i];
+
+		if (ext->type == EXT_KSYM) {
+			if (ext->ksym.type_id)
+				need_vmlinux_btf = true;
+			else
+				need_kallsyms = true;
+			continue;
+		} else if (ext->type == EXT_KCFG) {
+			void *ext_ptr = kcfg_data + ext->kcfg.data_off;
+			__u64 value = 0;
+
+			/* Kconfig externs need actual /proc/config.gz */
+			if (str_has_pfx(ext->name, "CONFIG_")) {
+				need_config = true;
+				continue;
+			}
+
+			/* Virtual kcfg externs are customly handled by libbpf */
+			if (strcmp(ext->name, "LINUX_KERNEL_VERSION") == 0) {
+				value = get_kernel_version();
+				if (!value) {
+					pr_warn("extern (kcfg) '%s': failed to get kernel version\n", ext->name);
+					return -EINVAL;
+				}
+			} else if (strcmp(ext->name, "LINUX_HAS_BPF_COOKIE") == 0) {
+				value = kernel_supports(obj, FEAT_BPF_COOKIE);
+			} else if (strcmp(ext->name, "LINUX_HAS_SYSCALL_WRAPPER") == 0) {
+				value = kernel_supports(obj, FEAT_SYSCALL_WRAPPER);
+			} else if (!str_has_pfx(ext->name, "LINUX_") || !ext->is_weak) {
+				/* Currently libbpf supports only CONFIG_ and LINUX_ prefixed
+				 * __kconfig externs, where LINUX_ ones are virtual and filled out
+				 * customly by libbpf (their values don't come from Kconfig).
+				 * If LINUX_xxx variable is not recognized by libbpf, but is marked
+				 * __weak, it defaults to zero value, just like for CONFIG_xxx
+				 * externs.
+				 */
+				pr_warn("extern (kcfg) '%s': unrecognized virtual extern\n", ext->name);
+				return -EINVAL;
+			}
+
+			err = set_kcfg_value_num(ext, ext_ptr, value);
+			if (err)
+				return err;
+			pr_debug("extern (kcfg) '%s': set to 0x%llx\n",
+				 ext->name, (long long)value);
+		} else {
+			pr_warn("extern '%s': unrecognized extern kind\n", ext->name);
+			return -EINVAL;
+		}
+	}
+	if (need_config && extra_kconfig) {
+		err = bpf_object__read_kconfig_mem(obj, extra_kconfig, kcfg_data);
+		if (err)
+			return -EINVAL;
+		need_config = false;
+		for (i = 0; i < obj->nr_extern; i++) {
+			ext = &obj->externs[i];
+			if (ext->type == EXT_KCFG && !ext->is_set) {
+				need_config = true;
+				break;
+			}
+		}
+	}
+	if (need_config) {
+		err = bpf_object__read_kconfig_file(obj, kcfg_data);
+		if (err)
+			return -EINVAL;
+	}
+	if (need_kallsyms) {
+		err = bpf_object__read_kallsyms_file(obj);
+		if (err)
+			return -EINVAL;
+	}
+	if (need_vmlinux_btf) {
+		err = bpf_object__resolve_ksyms_btf_id(obj);
+		if (err)
+			return -EINVAL;
+	}
+	for (i = 0; i < obj->nr_extern; i++) {
+		ext = &obj->externs[i];
+
+		if (!ext->is_set && !ext->is_weak) {
+			pr_warn("extern '%s' (strong): not resolved\n", ext->name);
+			return -ESRCH;
+		} else if (!ext->is_set) {
+			pr_debug("extern '%s' (weak): not resolved, defaulting to zero\n",
+				 ext->name);
+		}
+	}
+
+	return 0;
+}
+
+static int bpf_object_load(struct bpf_object *obj, int extra_log_level, const char *target_btf_path)
+{
+	int err, i;
+
+	if (!obj)
+		return libbpf_err(-EINVAL);
+
+	if (obj->loaded) {
+		pr_warn("object '%s': load can't be attempted twice\n", obj->name);
+		return libbpf_err(-EINVAL);
+	}
+
+	if (obj->gen_loader)
+		bpf_gen__init(obj->gen_loader, extra_log_level, obj->nr_programs, obj->nr_maps);
+
+	err = bpf_object__probe_loading(obj);
+	err = err ? : bpf_object__load_vmlinux_btf(obj, false);
+	err = err ? : bpf_object__resolve_externs(obj, obj->kconfig);
+	err = err ? : bpf_object__sanitize_and_load_btf(obj);
+	err = err ? : bpf_object__sanitize_maps(obj);
+	err = err ? : bpf_object__init_kern_struct_ops_maps(obj);
+	err = err ? : bpf_object__create_maps(obj);
+	err = err ? : bpf_object__relocate(obj, obj->btf_custom_path ? : target_btf_path);
+	err = err ? : bpf_object__load_progs(obj, extra_log_level);
+	err = err ? : bpf_object_init_prog_arrays(obj);
+
+	if (obj->gen_loader) {
+		/* reset FDs */
+		if (obj->btf)
+			btf__set_fd(obj->btf, -1);
+		for (i = 0; i < obj->nr_maps; i++)
+			obj->maps[i].fd = -1;
+		if (!err)
+			err = bpf_gen__finish(obj->gen_loader, obj->nr_programs, obj->nr_maps);
+	}
+
+	/* clean up fd_array */
+	zfree(&obj->fd_array);
+
+	/* clean up module BTFs */
+	for (i = 0; i < obj->btf_module_cnt; i++) {
+		close(obj->btf_modules[i].fd);
+		btf__free(obj->btf_modules[i].btf);
+		free(obj->btf_modules[i].name);
+	}
+	free(obj->btf_modules);
+
+	/* clean up vmlinux BTF */
+	btf__free(obj->btf_vmlinux);
+	obj->btf_vmlinux = NULL;
+
+	obj->loaded = true; /* doesn't matter if successfully or not */
+
+	if (err)
+		goto out;
+
+	return 0;
+out:
+	/* unpin any maps that were auto-pinned during load */
+	for (i = 0; i < obj->nr_maps; i++)
+		if (obj->maps[i].pinned && !obj->maps[i].reused)
+			bpf_map__unpin(&obj->maps[i], NULL);
+
+	bpf_object_unload(obj);
+	pr_warn("failed to load object '%s'\n", obj->path);
+	return libbpf_err(err);
+}
+
+int bpf_object__load(struct bpf_object *obj)
+{
+	return bpf_object_load(obj, 0, NULL);
+}
+
+static int make_parent_dir(const char *path)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	char *dname, *dir;
+	int err = 0;
+
+	dname = strdup(path);
+	if (dname == NULL)
+		return -ENOMEM;
+
+	dir = dirname(dname);
+	if (mkdir(dir, 0700) && errno != EEXIST)
+		err = -errno;
+
+	free(dname);
+	if (err) {
+		cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
+		pr_warn("failed to mkdir %s: %s\n", path, cp);
+	}
+	return err;
+}
+
+static int check_path(const char *path)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct statfs st_fs;
+	char *dname, *dir;
+	int err = 0;
+
+	if (path == NULL)
+		return -EINVAL;
+
+	dname = strdup(path);
+	if (dname == NULL)
+		return -ENOMEM;
+
+	dir = dirname(dname);
+	if (statfs(dir, &st_fs)) {
+		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+		pr_warn("failed to statfs %s: %s\n", dir, cp);
+		err = -errno;
+	}
+	free(dname);
+
+	if (!err && st_fs.f_type != BPF_FS_MAGIC) {
+		pr_warn("specified path %s is not on BPF FS\n", path);
+		err = -EINVAL;
+	}
+
+	return err;
+}
+
+int bpf_program__pin(struct bpf_program *prog, const char *path)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err;
+
+	if (prog->fd < 0) {
+		pr_warn("prog '%s': can't pin program that wasn't loaded\n", prog->name);
+		return libbpf_err(-EINVAL);
+	}
+
+	err = make_parent_dir(path);
+	if (err)
+		return libbpf_err(err);
+
+	err = check_path(path);
+	if (err)
+		return libbpf_err(err);
+
+	if (bpf_obj_pin(prog->fd, path)) {
+		err = -errno;
+		cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+		pr_warn("prog '%s': failed to pin at '%s': %s\n", prog->name, path, cp);
+		return libbpf_err(err);
+	}
+
+	pr_debug("prog '%s': pinned at '%s'\n", prog->name, path);
+	return 0;
+}
+
+int bpf_program__unpin(struct bpf_program *prog, const char *path)
+{
+	int err;
+
+	if (prog->fd < 0) {
+		pr_warn("prog '%s': can't unpin program that wasn't loaded\n", prog->name);
+		return libbpf_err(-EINVAL);
+	}
+
+	err = check_path(path);
+	if (err)
+		return libbpf_err(err);
+
+	err = unlink(path);
+	if (err)
+		return libbpf_err(-errno);
+
+	pr_debug("prog '%s': unpinned from '%s'\n", prog->name, path);
+	return 0;
+}
+
+int bpf_map__pin(struct bpf_map *map, const char *path)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err;
+
+	if (map == NULL) {
+		pr_warn("invalid map pointer\n");
+		return libbpf_err(-EINVAL);
+	}
+
+	if (map->pin_path) {
+		if (path && strcmp(path, map->pin_path)) {
+			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
+				bpf_map__name(map), map->pin_path, path);
+			return libbpf_err(-EINVAL);
+		} else if (map->pinned) {
+			pr_debug("map '%s' already pinned at '%s'; not re-pinning\n",
+				 bpf_map__name(map), map->pin_path);
+			return 0;
+		}
+	} else {
+		if (!path) {
+			pr_warn("missing a path to pin map '%s' at\n",
+				bpf_map__name(map));
+			return libbpf_err(-EINVAL);
+		} else if (map->pinned) {
+			pr_warn("map '%s' already pinned\n", bpf_map__name(map));
+			return libbpf_err(-EEXIST);
+		}
+
+		map->pin_path = strdup(path);
+		if (!map->pin_path) {
+			err = -errno;
+			goto out_err;
+		}
+	}
+
+	err = make_parent_dir(map->pin_path);
+	if (err)
+		return libbpf_err(err);
+
+	err = check_path(map->pin_path);
+	if (err)
+		return libbpf_err(err);
+
+	if (bpf_obj_pin(map->fd, map->pin_path)) {
+		err = -errno;
+		goto out_err;
+	}
+
+	map->pinned = true;
+	pr_debug("pinned map '%s'\n", map->pin_path);
+
+	return 0;
+
+out_err:
+	cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
+	pr_warn("failed to pin map: %s\n", cp);
+	return libbpf_err(err);
+}
+
+int bpf_map__unpin(struct bpf_map *map, const char *path)
+{
+	int err;
+
+	if (map == NULL) {
+		pr_warn("invalid map pointer\n");
+		return libbpf_err(-EINVAL);
+	}
+
+	if (map->pin_path) {
+		if (path && strcmp(path, map->pin_path)) {
+			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
+				bpf_map__name(map), map->pin_path, path);
+			return libbpf_err(-EINVAL);
+		}
+		path = map->pin_path;
+	} else if (!path) {
+		pr_warn("no path to unpin map '%s' from\n",
+			bpf_map__name(map));
+		return libbpf_err(-EINVAL);
+	}
+
+	err = check_path(path);
+	if (err)
+		return libbpf_err(err);
+
+	err = unlink(path);
+	if (err != 0)
+		return libbpf_err(-errno);
+
+	map->pinned = false;
+	pr_debug("unpinned map '%s' from '%s'\n", bpf_map__name(map), path);
+
+	return 0;
+}
+
+int bpf_map__set_pin_path(struct bpf_map *map, const char *path)
+{
+	char *new = NULL;
+
+	if (path) {
+		new = strdup(path);
+		if (!new)
+			return libbpf_err(-errno);
+	}
+
+	free(map->pin_path);
+	map->pin_path = new;
+	return 0;
+}
+
+__alias(bpf_map__pin_path)
+const char *bpf_map__get_pin_path(const struct bpf_map *map);
+
+const char *bpf_map__pin_path(const struct bpf_map *map)
+{
+	return map->pin_path;
+}
+
+bool bpf_map__is_pinned(const struct bpf_map *map)
+{
+	return map->pinned;
+}
+
+static void sanitize_pin_path(char *s)
+{
+	/* bpffs disallows periods in path names */
+	while (*s) {
+		if (*s == '.')
+			*s = '_';
+		s++;
+	}
+}
+
+int bpf_object__pin_maps(struct bpf_object *obj, const char *path)
+{
+	struct bpf_map *map;
+	int err;
+
+	if (!obj)
+		return libbpf_err(-ENOENT);
+
+	if (!obj->loaded) {
+		pr_warn("object not yet loaded; load it first\n");
+		return libbpf_err(-ENOENT);
+	}
+
+	bpf_object__for_each_map(map, obj) {
+		char *pin_path = NULL;
+		char buf[PATH_MAX];
+
+		if (!map->autocreate)
+			continue;
+
+		if (path) {
+			err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
+			if (err)
+				goto err_unpin_maps;
+			sanitize_pin_path(buf);
+			pin_path = buf;
+		} else if (!map->pin_path) {
+			continue;
+		}
+
+		err = bpf_map__pin(map, pin_path);
+		if (err)
+			goto err_unpin_maps;
+	}
+
+	return 0;
+
+err_unpin_maps:
+	while ((map = bpf_object__prev_map(obj, map))) {
+		if (!map->pin_path)
+			continue;
+
+		bpf_map__unpin(map, NULL);
+	}
+
+	return libbpf_err(err);
+}
+
+int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
+{
+	struct bpf_map *map;
+	int err;
+
+	if (!obj)
+		return libbpf_err(-ENOENT);
+
+	bpf_object__for_each_map(map, obj) {
+		char *pin_path = NULL;
+		char buf[PATH_MAX];
+
+		if (path) {
+			err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
+			if (err)
+				return libbpf_err(err);
+			sanitize_pin_path(buf);
+			pin_path = buf;
+		} else if (!map->pin_path) {
+			continue;
+		}
+
+		err = bpf_map__unpin(map, pin_path);
+		if (err)
+			return libbpf_err(err);
+	}
+
+	return 0;
+}
+
+int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
+{
+	struct bpf_program *prog;
+	char buf[PATH_MAX];
+	int err;
+
+	if (!obj)
+		return libbpf_err(-ENOENT);
+
+	if (!obj->loaded) {
+		pr_warn("object not yet loaded; load it first\n");
+		return libbpf_err(-ENOENT);
+	}
+
+	bpf_object__for_each_program(prog, obj) {
+		err = pathname_concat(buf, sizeof(buf), path, prog->name);
+		if (err)
+			goto err_unpin_programs;
+
+		err = bpf_program__pin(prog, buf);
+		if (err)
+			goto err_unpin_programs;
+	}
+
+	return 0;
+
+err_unpin_programs:
+	while ((prog = bpf_object__prev_program(obj, prog))) {
+		if (pathname_concat(buf, sizeof(buf), path, prog->name))
+			continue;
+
+		bpf_program__unpin(prog, buf);
+	}
+
+	return libbpf_err(err);
+}
+
+int bpf_object__unpin_programs(struct bpf_object *obj, const char *path)
+{
+	struct bpf_program *prog;
+	int err;
+
+	if (!obj)
+		return libbpf_err(-ENOENT);
+
+	bpf_object__for_each_program(prog, obj) {
+		char buf[PATH_MAX];
+
+		err = pathname_concat(buf, sizeof(buf), path, prog->name);
+		if (err)
+			return libbpf_err(err);
+
+		err = bpf_program__unpin(prog, buf);
+		if (err)
+			return libbpf_err(err);
+	}
+
+	return 0;
+}
+
+int bpf_object__pin(struct bpf_object *obj, const char *path)
+{
+	int err;
+
+	err = bpf_object__pin_maps(obj, path);
+	if (err)
+		return libbpf_err(err);
+
+	err = bpf_object__pin_programs(obj, path);
+	if (err) {
+		bpf_object__unpin_maps(obj, path);
+		return libbpf_err(err);
+	}
+
+	return 0;
+}
+
+static void bpf_map__destroy(struct bpf_map *map)
+{
+	if (map->inner_map) {
+		bpf_map__destroy(map->inner_map);
+		zfree(&map->inner_map);
+	}
+
+	zfree(&map->init_slots);
+	map->init_slots_sz = 0;
+
+	if (map->mmaped) {
+		munmap(map->mmaped, bpf_map_mmap_sz(map));
+		map->mmaped = NULL;
+	}
+
+	if (map->st_ops) {
+		zfree(&map->st_ops->data);
+		zfree(&map->st_ops->progs);
+		zfree(&map->st_ops->kern_func_off);
+		zfree(&map->st_ops);
+	}
+
+	zfree(&map->name);
+	zfree(&map->real_name);
+	zfree(&map->pin_path);
+
+	if (map->fd >= 0)
+		zclose(map->fd);
+}
+
+void bpf_object__close(struct bpf_object *obj)
+{
+	size_t i;
+
+	if (IS_ERR_OR_NULL(obj))
+		return;
+
+	usdt_manager_free(obj->usdt_man);
+	obj->usdt_man = NULL;
+
+	bpf_gen__free(obj->gen_loader);
+	bpf_object__elf_finish(obj);
+	bpf_object_unload(obj);
+	btf__free(obj->btf);
+	btf__free(obj->btf_vmlinux);
+	btf_ext__free(obj->btf_ext);
+
+	for (i = 0; i < obj->nr_maps; i++)
+		bpf_map__destroy(&obj->maps[i]);
+
+	zfree(&obj->btf_custom_path);
+	zfree(&obj->kconfig);
+	zfree(&obj->externs);
+	obj->nr_extern = 0;
+
+	zfree(&obj->maps);
+	obj->nr_maps = 0;
+
+	if (obj->programs && obj->nr_programs) {
+		for (i = 0; i < obj->nr_programs; i++)
+			bpf_program__exit(&obj->programs[i]);
+	}
+	zfree(&obj->programs);
+
+	free(obj);
+}
+
+const char *bpf_object__name(const struct bpf_object *obj)
+{
+	return obj ? obj->name : libbpf_err_ptr(-EINVAL);
+}
+
+unsigned int bpf_object__kversion(const struct bpf_object *obj)
+{
+	return obj ? obj->kern_version : 0;
+}
+
+struct btf *bpf_object__btf(const struct bpf_object *obj)
+{
+	return obj ? obj->btf : NULL;
+}
+
+int bpf_object__btf_fd(const struct bpf_object *obj)
+{
+	return obj->btf ? btf__fd(obj->btf) : -1;
+}
+
+int bpf_object__set_kversion(struct bpf_object *obj, __u32 kern_version)
+{
+	if (obj->loaded)
+		return libbpf_err(-EINVAL);
+
+	obj->kern_version = kern_version;
+
+	return 0;
+}
+
+int bpf_object__gen_loader(struct bpf_object *obj, struct gen_loader_opts *opts)
+{
+	struct bpf_gen *gen;
+
+	if (!opts)
+		return -EFAULT;
+	if (!OPTS_VALID(opts, gen_loader_opts))
+		return -EINVAL;
+	gen = calloc(sizeof(*gen), 1);
+	if (!gen)
+		return -ENOMEM;
+	gen->opts = opts;
+	obj->gen_loader = gen;
+	return 0;
+}
+
+static struct bpf_program *
+__bpf_program__iter(const struct bpf_program *p, const struct bpf_object *obj,
+		    bool forward)
+{
+	size_t nr_programs = obj->nr_programs;
+	ssize_t idx;
+
+	if (!nr_programs)
+		return NULL;
+
+	if (!p)
+		/* Iter from the beginning */
+		return forward ? &obj->programs[0] :
+			&obj->programs[nr_programs - 1];
+
+	if (p->obj != obj) {
+		pr_warn("error: program handler doesn't match object\n");
+		return errno = EINVAL, NULL;
+	}
+
+	idx = (p - obj->programs) + (forward ? 1 : -1);
+	if (idx >= obj->nr_programs || idx < 0)
+		return NULL;
+	return &obj->programs[idx];
+}
+
+struct bpf_program *
+bpf_object__next_program(const struct bpf_object *obj, struct bpf_program *prev)
+{
+	struct bpf_program *prog = prev;
+
+	do {
+		prog = __bpf_program__iter(prog, obj, true);
+	} while (prog && prog_is_subprog(obj, prog));
+
+	return prog;
+}
+
+struct bpf_program *
+bpf_object__prev_program(const struct bpf_object *obj, struct bpf_program *next)
+{
+	struct bpf_program *prog = next;
+
+	do {
+		prog = __bpf_program__iter(prog, obj, false);
+	} while (prog && prog_is_subprog(obj, prog));
+
+	return prog;
+}
+
+void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
+{
+	prog->prog_ifindex = ifindex;
+}
+
+const char *bpf_program__name(const struct bpf_program *prog)
+{
+	return prog->name;
+}
+
+const char *bpf_program__section_name(const struct bpf_program *prog)
+{
+	return prog->sec_name;
+}
+
+bool bpf_program__autoload(const struct bpf_program *prog)
+{
+	return prog->autoload;
+}
+
+int bpf_program__set_autoload(struct bpf_program *prog, bool autoload)
+{
+	if (prog->obj->loaded)
+		return libbpf_err(-EINVAL);
+
+	prog->autoload = autoload;
+	return 0;
+}
+
+bool bpf_program__autoattach(const struct bpf_program *prog)
+{
+	return prog->autoattach;
+}
+
+void bpf_program__set_autoattach(struct bpf_program *prog, bool autoattach)
+{
+	prog->autoattach = autoattach;
+}
+
+const struct bpf_insn *bpf_program__insns(const struct bpf_program *prog)
+{
+	return prog->insns;
+}
+
+size_t bpf_program__insn_cnt(const struct bpf_program *prog)
+{
+	return prog->insns_cnt;
+}
+
+int bpf_program__set_insns(struct bpf_program *prog,
+			   struct bpf_insn *new_insns, size_t new_insn_cnt)
+{
+	struct bpf_insn *insns;
+
+	if (prog->obj->loaded)
+		return -EBUSY;
+
+	insns = libbpf_reallocarray(prog->insns, new_insn_cnt, sizeof(*insns));
+	/* NULL is a valid return from reallocarray if the new count is zero */
+	if (!insns && new_insn_cnt) {
+		pr_warn("prog '%s': failed to realloc prog code\n", prog->name);
+		return -ENOMEM;
+	}
+	memcpy(insns, new_insns, new_insn_cnt * sizeof(*insns));
+
+	prog->insns = insns;
+	prog->insns_cnt = new_insn_cnt;
+	return 0;
+}
+
+int bpf_program__fd(const struct bpf_program *prog)
+{
+	if (!prog)
+		return libbpf_err(-EINVAL);
+
+	if (prog->fd < 0)
+		return libbpf_err(-ENOENT);
+
+	return prog->fd;
+}
+
+__alias(bpf_program__type)
+enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog);
+
+enum bpf_prog_type bpf_program__type(const struct bpf_program *prog)
+{
+	return prog->type;
+}
+
+int bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
+{
+	if (prog->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	prog->type = type;
+	return 0;
+}
+
+__alias(bpf_program__expected_attach_type)
+enum bpf_attach_type bpf_program__get_expected_attach_type(const struct bpf_program *prog);
+
+enum bpf_attach_type bpf_program__expected_attach_type(const struct bpf_program *prog)
+{
+	return prog->expected_attach_type;
+}
+
+int bpf_program__set_expected_attach_type(struct bpf_program *prog,
+					   enum bpf_attach_type type)
+{
+	if (prog->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	prog->expected_attach_type = type;
+	return 0;
+}
+
+__u32 bpf_program__flags(const struct bpf_program *prog)
+{
+	return prog->prog_flags;
+}
+
+int bpf_program__set_flags(struct bpf_program *prog, __u32 flags)
+{
+	if (prog->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	prog->prog_flags = flags;
+	return 0;
+}
+
+__u32 bpf_program__log_level(const struct bpf_program *prog)
+{
+	return prog->log_level;
+}
+
+int bpf_program__set_log_level(struct bpf_program *prog, __u32 log_level)
+{
+	if (prog->obj->loaded)
+		return libbpf_err(-EBUSY);
+
+	prog->log_level = log_level;
+	return 0;
+}
+
+const char *bpf_program__log_buf(const struct bpf_program *prog, size_t *log_size)
+{
+	*log_size = prog->log_size;
+	return prog->log_buf;
+}
+
+int bpf_program__set_log_buf(struct bpf_program *prog, char *log_buf, size_t log_size)
+{
+	if (log_size && !log_buf)
+		return -EINVAL;
+	if (prog->log_size > UINT_MAX)
+		return -EINVAL;
+	if (prog->obj->loaded)
+		return -EBUSY;
+
+	prog->log_buf = log_buf;
+	prog->log_size = log_size;
+	return 0;
+}
+
+#define SEC_DEF(sec_pfx, ptype, atype, flags, ...) {			    \
+	.sec = (char *)sec_pfx,						    \
+	.prog_type = BPF_PROG_TYPE_##ptype,				    \
+	.expected_attach_type = atype,					    \
+	.cookie = (long)(flags),					    \
+	.prog_prepare_load_fn = libbpf_prepare_prog_load,		    \
+	__VA_ARGS__							    \
+}
+
+static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_ksyscall(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_usdt(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+
+static const struct bpf_sec_def section_defs[] = {
+	SEC_DEF("socket",		SOCKET_FILTER, 0, SEC_NONE),
+	SEC_DEF("sk_reuseport/migrate",	SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, SEC_ATTACHABLE),
+	SEC_DEF("sk_reuseport",		SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT, SEC_ATTACHABLE),
+	SEC_DEF("kprobe+",		KPROBE,	0, SEC_NONE, attach_kprobe),
+	SEC_DEF("uprobe+",		KPROBE,	0, SEC_NONE, attach_uprobe),
+	SEC_DEF("uprobe.s+",		KPROBE,	0, SEC_SLEEPABLE, attach_uprobe),
+	SEC_DEF("kretprobe+",		KPROBE, 0, SEC_NONE, attach_kprobe),
+	SEC_DEF("uretprobe+",		KPROBE, 0, SEC_NONE, attach_uprobe),
+	SEC_DEF("uretprobe.s+",		KPROBE, 0, SEC_SLEEPABLE, attach_uprobe),
+	SEC_DEF("kprobe.multi+",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
+	SEC_DEF("kretprobe.multi+",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
+	SEC_DEF("ksyscall+",		KPROBE,	0, SEC_NONE, attach_ksyscall),
+	SEC_DEF("kretsyscall+",		KPROBE, 0, SEC_NONE, attach_ksyscall),
+	SEC_DEF("usdt+",		KPROBE,	0, SEC_NONE, attach_usdt),
+	SEC_DEF("tc",			SCHED_CLS, 0, SEC_NONE),
+	SEC_DEF("classifier",		SCHED_CLS, 0, SEC_NONE),
+	SEC_DEF("action",		SCHED_ACT, 0, SEC_NONE),
+	SEC_DEF("tracepoint+",		TRACEPOINT, 0, SEC_NONE, attach_tp),
+	SEC_DEF("tp+",			TRACEPOINT, 0, SEC_NONE, attach_tp),
+	SEC_DEF("raw_tracepoint+",	RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("raw_tp+",		RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("raw_tracepoint.w+",	RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("raw_tp.w+",		RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("tp_btf+",		TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fentry+",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fmod_ret+",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fexit+",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fentry.s+",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+	SEC_DEF("fmod_ret.s+",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+	SEC_DEF("fexit.s+",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+	SEC_DEF("freplace+",		EXT, 0, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("lsm+",			LSM, BPF_LSM_MAC, SEC_ATTACH_BTF, attach_lsm),
+	SEC_DEF("lsm.s+",		LSM, BPF_LSM_MAC, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_lsm),
+	SEC_DEF("lsm_cgroup+",		LSM, BPF_LSM_CGROUP, SEC_ATTACH_BTF),
+	SEC_DEF("iter+",		TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF, attach_iter),
+	SEC_DEF("iter.s+",		TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_iter),
+	SEC_DEF("syscall",		SYSCALL, 0, SEC_SLEEPABLE),
+	SEC_DEF("xdp.frags/devmap",	XDP, BPF_XDP_DEVMAP, SEC_XDP_FRAGS),
+	SEC_DEF("xdp/devmap",		XDP, BPF_XDP_DEVMAP, SEC_ATTACHABLE),
+	SEC_DEF("xdp.frags/cpumap",	XDP, BPF_XDP_CPUMAP, SEC_XDP_FRAGS),
+	SEC_DEF("xdp/cpumap",		XDP, BPF_XDP_CPUMAP, SEC_ATTACHABLE),
+	SEC_DEF("xdp.frags",		XDP, BPF_XDP, SEC_XDP_FRAGS),
+	SEC_DEF("xdp",			XDP, BPF_XDP, SEC_ATTACHABLE_OPT),
+	SEC_DEF("perf_event",		PERF_EVENT, 0, SEC_NONE),
+	SEC_DEF("lwt_in",		LWT_IN, 0, SEC_NONE),
+	SEC_DEF("lwt_out",		LWT_OUT, 0, SEC_NONE),
+	SEC_DEF("lwt_xmit",		LWT_XMIT, 0, SEC_NONE),
+	SEC_DEF("lwt_seg6local",	LWT_SEG6LOCAL, 0, SEC_NONE),
+	SEC_DEF("sockops",		SOCK_OPS, BPF_CGROUP_SOCK_OPS, SEC_ATTACHABLE_OPT),
+	SEC_DEF("sk_skb/stream_parser",	SK_SKB, BPF_SK_SKB_STREAM_PARSER, SEC_ATTACHABLE_OPT),
+	SEC_DEF("sk_skb/stream_verdict",SK_SKB, BPF_SK_SKB_STREAM_VERDICT, SEC_ATTACHABLE_OPT),
+	SEC_DEF("sk_skb",		SK_SKB, 0, SEC_NONE),
+	SEC_DEF("sk_msg",		SK_MSG, BPF_SK_MSG_VERDICT, SEC_ATTACHABLE_OPT),
+	SEC_DEF("lirc_mode2",		LIRC_MODE2, BPF_LIRC_MODE2, SEC_ATTACHABLE_OPT),
+	SEC_DEF("flow_dissector",	FLOW_DISSECTOR, BPF_FLOW_DISSECTOR, SEC_ATTACHABLE_OPT),
+	SEC_DEF("cgroup_skb/ingress",	CGROUP_SKB, BPF_CGROUP_INET_INGRESS, SEC_ATTACHABLE_OPT),
+	SEC_DEF("cgroup_skb/egress",	CGROUP_SKB, BPF_CGROUP_INET_EGRESS, SEC_ATTACHABLE_OPT),
+	SEC_DEF("cgroup/skb",		CGROUP_SKB, 0, SEC_NONE),
+	SEC_DEF("cgroup/sock_create",	CGROUP_SOCK, BPF_CGROUP_INET_SOCK_CREATE, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/sock_release",	CGROUP_SOCK, BPF_CGROUP_INET_SOCK_RELEASE, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/sock",		CGROUP_SOCK, BPF_CGROUP_INET_SOCK_CREATE, SEC_ATTACHABLE_OPT),
+	SEC_DEF("cgroup/post_bind4",	CGROUP_SOCK, BPF_CGROUP_INET4_POST_BIND, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/post_bind6",	CGROUP_SOCK, BPF_CGROUP_INET6_POST_BIND, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/bind4",		CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_BIND, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/bind6",		CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_BIND, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/connect4",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_CONNECT, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/connect6",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_CONNECT, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/sendmsg4",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP4_SENDMSG, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/sendmsg6",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP6_SENDMSG, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/recvmsg4",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP4_RECVMSG, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/recvmsg6",	CGROUP_SOCK_ADDR, BPF_CGROUP_UDP6_RECVMSG, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/getpeername4",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_GETPEERNAME, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/getpeername6",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_GETPEERNAME, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/getsockname4",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_GETSOCKNAME, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/getsockname6",	CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_GETSOCKNAME, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/sysctl",	CGROUP_SYSCTL, BPF_CGROUP_SYSCTL, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/getsockopt",	CGROUP_SOCKOPT, BPF_CGROUP_GETSOCKOPT, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/setsockopt",	CGROUP_SOCKOPT, BPF_CGROUP_SETSOCKOPT, SEC_ATTACHABLE),
+	SEC_DEF("cgroup/dev",		CGROUP_DEVICE, BPF_CGROUP_DEVICE, SEC_ATTACHABLE_OPT),
+	SEC_DEF("struct_ops+",		STRUCT_OPS, 0, SEC_NONE),
+	SEC_DEF("sk_lookup",		SK_LOOKUP, BPF_SK_LOOKUP, SEC_ATTACHABLE),
+};
+
+static size_t custom_sec_def_cnt;
+static struct bpf_sec_def *custom_sec_defs;
+static struct bpf_sec_def custom_fallback_def;
+static bool has_custom_fallback_def;
+
+static int last_custom_sec_def_handler_id;
+
+int libbpf_register_prog_handler(const char *sec,
+				 enum bpf_prog_type prog_type,
+				 enum bpf_attach_type exp_attach_type,
+				 const struct libbpf_prog_handler_opts *opts)
+{
+	struct bpf_sec_def *sec_def;
+
+	if (!OPTS_VALID(opts, libbpf_prog_handler_opts))
+		return libbpf_err(-EINVAL);
+
+	if (last_custom_sec_def_handler_id == INT_MAX) /* prevent overflow */
+		return libbpf_err(-E2BIG);
+
+	if (sec) {
+		sec_def = libbpf_reallocarray(custom_sec_defs, custom_sec_def_cnt + 1,
+					      sizeof(*sec_def));
+		if (!sec_def)
+			return libbpf_err(-ENOMEM);
+
+		custom_sec_defs = sec_def;
+		sec_def = &custom_sec_defs[custom_sec_def_cnt];
+	} else {
+		if (has_custom_fallback_def)
+			return libbpf_err(-EBUSY);
+
+		sec_def = &custom_fallback_def;
+	}
+
+	sec_def->sec = sec ? strdup(sec) : NULL;
+	if (sec && !sec_def->sec)
+		return libbpf_err(-ENOMEM);
+
+	sec_def->prog_type = prog_type;
+	sec_def->expected_attach_type = exp_attach_type;
+	sec_def->cookie = OPTS_GET(opts, cookie, 0);
+
+	sec_def->prog_setup_fn = OPTS_GET(opts, prog_setup_fn, NULL);
+	sec_def->prog_prepare_load_fn = OPTS_GET(opts, prog_prepare_load_fn, NULL);
+	sec_def->prog_attach_fn = OPTS_GET(opts, prog_attach_fn, NULL);
+
+	sec_def->handler_id = ++last_custom_sec_def_handler_id;
+
+	if (sec)
+		custom_sec_def_cnt++;
+	else
+		has_custom_fallback_def = true;
+
+	return sec_def->handler_id;
+}
+
+int libbpf_unregister_prog_handler(int handler_id)
+{
+	struct bpf_sec_def *sec_defs;
+	int i;
+
+	if (handler_id <= 0)
+		return libbpf_err(-EINVAL);
+
+	if (has_custom_fallback_def && custom_fallback_def.handler_id == handler_id) {
+		memset(&custom_fallback_def, 0, sizeof(custom_fallback_def));
+		has_custom_fallback_def = false;
+		return 0;
+	}
+
+	for (i = 0; i < custom_sec_def_cnt; i++) {
+		if (custom_sec_defs[i].handler_id == handler_id)
+			break;
+	}
+
+	if (i == custom_sec_def_cnt)
+		return libbpf_err(-ENOENT);
+
+	free(custom_sec_defs[i].sec);
+	for (i = i + 1; i < custom_sec_def_cnt; i++)
+		custom_sec_defs[i - 1] = custom_sec_defs[i];
+	custom_sec_def_cnt--;
+
+	/* try to shrink the array, but it's ok if we couldn't */
+	sec_defs = libbpf_reallocarray(custom_sec_defs, custom_sec_def_cnt, sizeof(*sec_defs));
+	/* if new count is zero, reallocarray can return a valid NULL result;
+	 * in this case the previous pointer will be freed, so we *have to*
+	 * reassign old pointer to the new value (even if it's NULL)
+	 */
+	if (sec_defs || custom_sec_def_cnt == 0)
+		custom_sec_defs = sec_defs;
+
+	return 0;
+}
+
+static bool sec_def_matches(const struct bpf_sec_def *sec_def, const char *sec_name)
+{
+	size_t len = strlen(sec_def->sec);
+
+	/* "type/" always has to have proper SEC("type/extras") form */
+	if (sec_def->sec[len - 1] == '/') {
+		if (str_has_pfx(sec_name, sec_def->sec))
+			return true;
+		return false;
+	}
+
+	/* "type+" means it can be either exact SEC("type") or
+	 * well-formed SEC("type/extras") with proper '/' separator
+	 */
+	if (sec_def->sec[len - 1] == '+') {
+		len--;
+		/* not even a prefix */
+		if (strncmp(sec_name, sec_def->sec, len) != 0)
+			return false;
+		/* exact match or has '/' separator */
+		if (sec_name[len] == '\0' || sec_name[len] == '/')
+			return true;
+		return false;
+	}
+
+	return strcmp(sec_name, sec_def->sec) == 0;
+}
+
+static const struct bpf_sec_def *find_sec_def(const char *sec_name)
+{
+	const struct bpf_sec_def *sec_def;
+	int i, n;
+
+	n = custom_sec_def_cnt;
+	for (i = 0; i < n; i++) {
+		sec_def = &custom_sec_defs[i];
+		if (sec_def_matches(sec_def, sec_name))
+			return sec_def;
+	}
+
+	n = ARRAY_SIZE(section_defs);
+	for (i = 0; i < n; i++) {
+		sec_def = &section_defs[i];
+		if (sec_def_matches(sec_def, sec_name))
+			return sec_def;
+	}
+
+	if (has_custom_fallback_def)
+		return &custom_fallback_def;
+
+	return NULL;
+}
+
+#define MAX_TYPE_NAME_SIZE 32
+
+static char *libbpf_get_type_names(bool attach_type)
+{
+	int i, len = ARRAY_SIZE(section_defs) * MAX_TYPE_NAME_SIZE;
+	char *buf;
+
+	buf = malloc(len);
+	if (!buf)
+		return NULL;
+
+	buf[0] = '\0';
+	/* Forge string buf with all available names */
+	for (i = 0; i < ARRAY_SIZE(section_defs); i++) {
+		const struct bpf_sec_def *sec_def = &section_defs[i];
+
+		if (attach_type) {
+			if (sec_def->prog_prepare_load_fn != libbpf_prepare_prog_load)
+				continue;
+
+			if (!(sec_def->cookie & SEC_ATTACHABLE))
+				continue;
+		}
+
+		if (strlen(buf) + strlen(section_defs[i].sec) + 2 > len) {
+			free(buf);
+			return NULL;
+		}
+		strcat(buf, " ");
+		strcat(buf, section_defs[i].sec);
+	}
+
+	return buf;
+}
+
+int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
+			     enum bpf_attach_type *expected_attach_type)
+{
+	const struct bpf_sec_def *sec_def;
+	char *type_names;
+
+	if (!name)
+		return libbpf_err(-EINVAL);
+
+	sec_def = find_sec_def(name);
+	if (sec_def) {
+		*prog_type = sec_def->prog_type;
+		*expected_attach_type = sec_def->expected_attach_type;
+		return 0;
+	}
+
+	pr_debug("failed to guess program type from ELF section '%s'\n", name);
+	type_names = libbpf_get_type_names(false);
+	if (type_names != NULL) {
+		pr_debug("supported section(type) names are:%s\n", type_names);
+		free(type_names);
+	}
+
+	return libbpf_err(-ESRCH);
+}
+
+const char *libbpf_bpf_attach_type_str(enum bpf_attach_type t)
+{
+	if (t < 0 || t >= ARRAY_SIZE(attach_type_name))
+		return NULL;
+
+	return attach_type_name[t];
+}
+
+const char *libbpf_bpf_link_type_str(enum bpf_link_type t)
+{
+	if (t < 0 || t >= ARRAY_SIZE(link_type_name))
+		return NULL;
+
+	return link_type_name[t];
+}
+
+const char *libbpf_bpf_map_type_str(enum bpf_map_type t)
+{
+	if (t < 0 || t >= ARRAY_SIZE(map_type_name))
+		return NULL;
+
+	return map_type_name[t];
+}
+
+const char *libbpf_bpf_prog_type_str(enum bpf_prog_type t)
+{
+	if (t < 0 || t >= ARRAY_SIZE(prog_type_name))
+		return NULL;
+
+	return prog_type_name[t];
+}
+
+static struct bpf_map *find_struct_ops_map_by_offset(struct bpf_object *obj,
+						     size_t offset)
+{
+	struct bpf_map *map;
+	size_t i;
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		map = &obj->maps[i];
+		if (!bpf_map__is_struct_ops(map))
+			continue;
+		if (map->sec_offset <= offset &&
+		    offset - map->sec_offset < map->def.value_size)
+			return map;
+	}
+
+	return NULL;
+}
+
+/* Collect the reloc from ELF and populate the st_ops->progs[] */
+static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
+					    Elf64_Shdr *shdr, Elf_Data *data)
+{
+	const struct btf_member *member;
+	struct bpf_struct_ops *st_ops;
+	struct bpf_program *prog;
+	unsigned int shdr_idx;
+	const struct btf *btf;
+	struct bpf_map *map;
+	unsigned int moff, insn_idx;
+	const char *name;
+	__u32 member_idx;
+	Elf64_Sym *sym;
+	Elf64_Rel *rel;
+	int i, nrels;
+
+	btf = obj->btf;
+	nrels = shdr->sh_size / shdr->sh_entsize;
+	for (i = 0; i < nrels; i++) {
+		rel = elf_rel_by_idx(data, i);
+		if (!rel) {
+			pr_warn("struct_ops reloc: failed to get %d reloc\n", i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info));
+		if (!sym) {
+			pr_warn("struct_ops reloc: symbol %zx not found\n",
+				(size_t)ELF64_R_SYM(rel->r_info));
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		name = elf_sym_str(obj, sym->st_name) ?: "<?>";
+		map = find_struct_ops_map_by_offset(obj, rel->r_offset);
+		if (!map) {
+			pr_warn("struct_ops reloc: cannot find map at rel->r_offset %zu\n",
+				(size_t)rel->r_offset);
+			return -EINVAL;
+		}
+
+		moff = rel->r_offset - map->sec_offset;
+		shdr_idx = sym->st_shndx;
+		st_ops = map->st_ops;
+		pr_debug("struct_ops reloc %s: for %lld value %lld shdr_idx %u rel->r_offset %zu map->sec_offset %zu name %d (\'%s\')\n",
+			 map->name,
+			 (long long)(rel->r_info >> 32),
+			 (long long)sym->st_value,
+			 shdr_idx, (size_t)rel->r_offset,
+			 map->sec_offset, sym->st_name, name);
+
+		if (shdr_idx >= SHN_LORESERVE) {
+			pr_warn("struct_ops reloc %s: rel->r_offset %zu shdr_idx %u unsupported non-static function\n",
+				map->name, (size_t)rel->r_offset, shdr_idx);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		if (sym->st_value % BPF_INSN_SZ) {
+			pr_warn("struct_ops reloc %s: invalid target program offset %llu\n",
+				map->name, (unsigned long long)sym->st_value);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+		insn_idx = sym->st_value / BPF_INSN_SZ;
+
+		member = find_member_by_offset(st_ops->type, moff * 8);
+		if (!member) {
+			pr_warn("struct_ops reloc %s: cannot find member at moff %u\n",
+				map->name, moff);
+			return -EINVAL;
+		}
+		member_idx = member - btf_members(st_ops->type);
+		name = btf__name_by_offset(btf, member->name_off);
+
+		if (!resolve_func_ptr(btf, member->type, NULL)) {
+			pr_warn("struct_ops reloc %s: cannot relocate non func ptr %s\n",
+				map->name, name);
+			return -EINVAL;
+		}
+
+		prog = find_prog_by_sec_insn(obj, shdr_idx, insn_idx);
+		if (!prog) {
+			pr_warn("struct_ops reloc %s: cannot find prog at shdr_idx %u to relocate func ptr %s\n",
+				map->name, shdr_idx, name);
+			return -EINVAL;
+		}
+
+		/* prevent the use of BPF prog with invalid type */
+		if (prog->type != BPF_PROG_TYPE_STRUCT_OPS) {
+			pr_warn("struct_ops reloc %s: prog %s is not struct_ops BPF program\n",
+				map->name, prog->name);
+			return -EINVAL;
+		}
+
+		/* if we haven't yet processed this BPF program, record proper
+		 * attach_btf_id and member_idx
+		 */
+		if (!prog->attach_btf_id) {
+			prog->attach_btf_id = st_ops->type_id;
+			prog->expected_attach_type = member_idx;
+		}
+
+		/* struct_ops BPF prog can be re-used between multiple
+		 * .struct_ops as long as it's the same struct_ops struct
+		 * definition and the same function pointer field
+		 */
+		if (prog->attach_btf_id != st_ops->type_id ||
+		    prog->expected_attach_type != member_idx) {
+			pr_warn("struct_ops reloc %s: cannot use prog %s in sec %s with type %u attach_btf_id %u expected_attach_type %u for func ptr %s\n",
+				map->name, prog->name, prog->sec_name, prog->type,
+				prog->attach_btf_id, prog->expected_attach_type, name);
+			return -EINVAL;
+		}
+
+		st_ops->progs[member_idx] = prog;
+	}
+
+	return 0;
+}
+
+#define BTF_TRACE_PREFIX "btf_trace_"
+#define BTF_LSM_PREFIX "bpf_lsm_"
+#define BTF_ITER_PREFIX "bpf_iter_"
+#define BTF_MAX_NAME_SIZE 128
+
+void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,
+				const char **prefix, int *kind)
+{
+	switch (attach_type) {
+	case BPF_TRACE_RAW_TP:
+		*prefix = BTF_TRACE_PREFIX;
+		*kind = BTF_KIND_TYPEDEF;
+		break;
+	case BPF_LSM_MAC:
+	case BPF_LSM_CGROUP:
+		*prefix = BTF_LSM_PREFIX;
+		*kind = BTF_KIND_FUNC;
+		break;
+	case BPF_TRACE_ITER:
+		*prefix = BTF_ITER_PREFIX;
+		*kind = BTF_KIND_FUNC;
+		break;
+	default:
+		*prefix = "";
+		*kind = BTF_KIND_FUNC;
+	}
+}
+
+static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
+				   const char *name, __u32 kind)
+{
+	char btf_type_name[BTF_MAX_NAME_SIZE];
+	int ret;
+
+	ret = snprintf(btf_type_name, sizeof(btf_type_name),
+		       "%s%s", prefix, name);
+	/* snprintf returns the number of characters written excluding the
+	 * terminating null. So, if >= BTF_MAX_NAME_SIZE are written, it
+	 * indicates truncation.
+	 */
+	if (ret < 0 || ret >= sizeof(btf_type_name))
+		return -ENAMETOOLONG;
+	return btf__find_by_name_kind(btf, btf_type_name, kind);
+}
+
+static inline int find_attach_btf_id(struct btf *btf, const char *name,
+				     enum bpf_attach_type attach_type)
+{
+	const char *prefix;
+	int kind;
+
+	btf_get_kernel_prefix_kind(attach_type, &prefix, &kind);
+	return find_btf_by_prefix_kind(btf, prefix, name, kind);
+}
+
+int libbpf_find_vmlinux_btf_id(const char *name,
+			       enum bpf_attach_type attach_type)
+{
+	struct btf *btf;
+	int err;
+
+	btf = btf__load_vmlinux_btf();
+	err = libbpf_get_error(btf);
+	if (err) {
+		pr_warn("vmlinux BTF is not found\n");
+		return libbpf_err(err);
+	}
+
+	err = find_attach_btf_id(btf, name, attach_type);
+	if (err <= 0)
+		pr_warn("%s is not found in vmlinux BTF\n", name);
+
+	btf__free(btf);
+	return libbpf_err(err);
+}
+
+static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
+{
+	struct bpf_prog_info info;
+	__u32 info_len = sizeof(info);
+	struct btf *btf;
+	int err;
+
+	memset(&info, 0, info_len);
+	err = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len);
+	if (err) {
+		pr_warn("failed bpf_obj_get_info_by_fd for FD %d: %d\n",
+			attach_prog_fd, err);
+		return err;
+	}
+
+	err = -EINVAL;
+	if (!info.btf_id) {
+		pr_warn("The target program doesn't have BTF\n");
+		goto out;
+	}
+	btf = btf__load_from_kernel_by_id(info.btf_id);
+	err = libbpf_get_error(btf);
+	if (err) {
+		pr_warn("Failed to get BTF %d of the program: %d\n", info.btf_id, err);
+		goto out;
+	}
+	err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
+	btf__free(btf);
+	if (err <= 0) {
+		pr_warn("%s is not found in prog's BTF\n", name);
+		goto out;
+	}
+out:
+	return err;
+}
+
+static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name,
+			      enum bpf_attach_type attach_type,
+			      int *btf_obj_fd, int *btf_type_id)
+{
+	int ret, i;
+
+	ret = find_attach_btf_id(obj->btf_vmlinux, attach_name, attach_type);
+	if (ret > 0) {
+		*btf_obj_fd = 0; /* vmlinux BTF */
+		*btf_type_id = ret;
+		return 0;
+	}
+	if (ret != -ENOENT)
+		return ret;
+
+	ret = load_module_btfs(obj);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < obj->btf_module_cnt; i++) {
+		const struct module_btf *mod = &obj->btf_modules[i];
+
+		ret = find_attach_btf_id(mod->btf, attach_name, attach_type);
+		if (ret > 0) {
+			*btf_obj_fd = mod->fd;
+			*btf_type_id = ret;
+			return 0;
+		}
+		if (ret == -ENOENT)
+			continue;
+
+		return ret;
+	}
+
+	return -ESRCH;
+}
+
+static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attach_name,
+				     int *btf_obj_fd, int *btf_type_id)
+{
+	enum bpf_attach_type attach_type = prog->expected_attach_type;
+	__u32 attach_prog_fd = prog->attach_prog_fd;
+	int err = 0;
+
+	/* BPF program's BTF ID */
+	if (prog->type == BPF_PROG_TYPE_EXT || attach_prog_fd) {
+		if (!attach_prog_fd) {
+			pr_warn("prog '%s': attach program FD is not set\n", prog->name);
+			return -EINVAL;
+		}
+		err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd);
+		if (err < 0) {
+			pr_warn("prog '%s': failed to find BPF program (FD %d) BTF ID for '%s': %d\n",
+				 prog->name, attach_prog_fd, attach_name, err);
+			return err;
+		}
+		*btf_obj_fd = 0;
+		*btf_type_id = err;
+		return 0;
+	}
+
+	/* kernel/module BTF ID */
+	if (prog->obj->gen_loader) {
+		bpf_gen__record_attach_target(prog->obj->gen_loader, attach_name, attach_type);
+		*btf_obj_fd = 0;
+		*btf_type_id = 1;
+	} else {
+		err = find_kernel_btf_id(prog->obj, attach_name, attach_type, btf_obj_fd, btf_type_id);
+	}
+	if (err) {
+		pr_warn("prog '%s': failed to find kernel BTF type ID of '%s': %d\n",
+			prog->name, attach_name, err);
+		return err;
+	}
+	return 0;
+}
+
+int libbpf_attach_type_by_name(const char *name,
+			       enum bpf_attach_type *attach_type)
+{
+	char *type_names;
+	const struct bpf_sec_def *sec_def;
+
+	if (!name)
+		return libbpf_err(-EINVAL);
+
+	sec_def = find_sec_def(name);
+	if (!sec_def) {
+		pr_debug("failed to guess attach type based on ELF section name '%s'\n", name);
+		type_names = libbpf_get_type_names(true);
+		if (type_names != NULL) {
+			pr_debug("attachable section(type) names are:%s\n", type_names);
+			free(type_names);
+		}
+
+		return libbpf_err(-EINVAL);
+	}
+
+	if (sec_def->prog_prepare_load_fn != libbpf_prepare_prog_load)
+		return libbpf_err(-EINVAL);
+	if (!(sec_def->cookie & SEC_ATTACHABLE))
+		return libbpf_err(-EINVAL);
+
+	*attach_type = sec_def->expected_attach_type;
+	return 0;
+}
+
+int bpf_map__fd(const struct bpf_map *map)
+{
+	return map ? map->fd : libbpf_err(-EINVAL);
+}
+
+static bool map_uses_real_name(const struct bpf_map *map)
+{
+	/* Since libbpf started to support custom .data.* and .rodata.* maps,
+	 * their user-visible name differs from kernel-visible name. Users see
+	 * such map's corresponding ELF section name as a map name.
+	 * This check distinguishes .data/.rodata from .data.* and .rodata.*
+	 * maps to know which name has to be returned to the user.
+	 */
+	if (map->libbpf_type == LIBBPF_MAP_DATA && strcmp(map->real_name, DATA_SEC) != 0)
+		return true;
+	if (map->libbpf_type == LIBBPF_MAP_RODATA && strcmp(map->real_name, RODATA_SEC) != 0)
+		return true;
+	return false;
+}
+
+const char *bpf_map__name(const struct bpf_map *map)
+{
+	if (!map)
+		return NULL;
+
+	if (map_uses_real_name(map))
+		return map->real_name;
+
+	return map->name;
+}
+
+enum bpf_map_type bpf_map__type(const struct bpf_map *map)
+{
+	return map->def.type;
+}
+
+int bpf_map__set_type(struct bpf_map *map, enum bpf_map_type type)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->def.type = type;
+	return 0;
+}
+
+__u32 bpf_map__map_flags(const struct bpf_map *map)
+{
+	return map->def.map_flags;
+}
+
+int bpf_map__set_map_flags(struct bpf_map *map, __u32 flags)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->def.map_flags = flags;
+	return 0;
+}
+
+__u64 bpf_map__map_extra(const struct bpf_map *map)
+{
+	return map->map_extra;
+}
+
+int bpf_map__set_map_extra(struct bpf_map *map, __u64 map_extra)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->map_extra = map_extra;
+	return 0;
+}
+
+__u32 bpf_map__numa_node(const struct bpf_map *map)
+{
+	return map->numa_node;
+}
+
+int bpf_map__set_numa_node(struct bpf_map *map, __u32 numa_node)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->numa_node = numa_node;
+	return 0;
+}
+
+__u32 bpf_map__key_size(const struct bpf_map *map)
+{
+	return map->def.key_size;
+}
+
+int bpf_map__set_key_size(struct bpf_map *map, __u32 size)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->def.key_size = size;
+	return 0;
+}
+
+__u32 bpf_map__value_size(const struct bpf_map *map)
+{
+	return map->def.value_size;
+}
+
+int bpf_map__set_value_size(struct bpf_map *map, __u32 size)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->def.value_size = size;
+	return 0;
+}
+
+__u32 bpf_map__btf_key_type_id(const struct bpf_map *map)
+{
+	return map ? map->btf_key_type_id : 0;
+}
+
+__u32 bpf_map__btf_value_type_id(const struct bpf_map *map)
+{
+	return map ? map->btf_value_type_id : 0;
+}
+
+int bpf_map__set_initial_value(struct bpf_map *map,
+			       const void *data, size_t size)
+{
+	if (!map->mmaped || map->libbpf_type == LIBBPF_MAP_KCONFIG ||
+	    size != map->def.value_size || map->fd >= 0)
+		return libbpf_err(-EINVAL);
+
+	memcpy(map->mmaped, data, size);
+	return 0;
+}
+
+const void *bpf_map__initial_value(struct bpf_map *map, size_t *psize)
+{
+	if (!map->mmaped)
+		return NULL;
+	*psize = map->def.value_size;
+	return map->mmaped;
+}
+
+bool bpf_map__is_internal(const struct bpf_map *map)
+{
+	return map->libbpf_type != LIBBPF_MAP_UNSPEC;
+}
+
+__u32 bpf_map__ifindex(const struct bpf_map *map)
+{
+	return map->map_ifindex;
+}
+
+int bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->map_ifindex = ifindex;
+	return 0;
+}
+
+int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)
+{
+	if (!bpf_map_type__is_map_in_map(map->def.type)) {
+		pr_warn("error: unsupported map type\n");
+		return libbpf_err(-EINVAL);
+	}
+	if (map->inner_map_fd != -1) {
+		pr_warn("error: inner_map_fd already specified\n");
+		return libbpf_err(-EINVAL);
+	}
+	if (map->inner_map) {
+		bpf_map__destroy(map->inner_map);
+		zfree(&map->inner_map);
+	}
+	map->inner_map_fd = fd;
+	return 0;
+}
+
+static struct bpf_map *
+__bpf_map__iter(const struct bpf_map *m, const struct bpf_object *obj, int i)
+{
+	ssize_t idx;
+	struct bpf_map *s, *e;
+
+	if (!obj || !obj->maps)
+		return errno = EINVAL, NULL;
+
+	s = obj->maps;
+	e = obj->maps + obj->nr_maps;
+
+	if ((m < s) || (m >= e)) {
+		pr_warn("error in %s: map handler doesn't belong to object\n",
+			 __func__);
+		return errno = EINVAL, NULL;
+	}
+
+	idx = (m - obj->maps) + i;
+	if (idx >= obj->nr_maps || idx < 0)
+		return NULL;
+	return &obj->maps[idx];
+}
+
+struct bpf_map *
+bpf_object__next_map(const struct bpf_object *obj, const struct bpf_map *prev)
+{
+	if (prev == NULL)
+		return obj->maps;
+
+	return __bpf_map__iter(prev, obj, 1);
+}
+
+struct bpf_map *
+bpf_object__prev_map(const struct bpf_object *obj, const struct bpf_map *next)
+{
+	if (next == NULL) {
+		if (!obj->nr_maps)
+			return NULL;
+		return obj->maps + obj->nr_maps - 1;
+	}
+
+	return __bpf_map__iter(next, obj, -1);
+}
+
+struct bpf_map *
+bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name)
+{
+	struct bpf_map *pos;
+
+	bpf_object__for_each_map(pos, obj) {
+		/* if it's a special internal map name (which always starts
+		 * with dot) then check if that special name matches the
+		 * real map name (ELF section name)
+		 */
+		if (name[0] == '.') {
+			if (pos->real_name && strcmp(pos->real_name, name) == 0)
+				return pos;
+			continue;
+		}
+		/* otherwise map name has to be an exact match */
+		if (map_uses_real_name(pos)) {
+			if (strcmp(pos->real_name, name) == 0)
+				return pos;
+			continue;
+		}
+		if (strcmp(pos->name, name) == 0)
+			return pos;
+	}
+	return errno = ENOENT, NULL;
+}
+
+int
+bpf_object__find_map_fd_by_name(const struct bpf_object *obj, const char *name)
+{
+	return bpf_map__fd(bpf_object__find_map_by_name(obj, name));
+}
+
+static int validate_map_op(const struct bpf_map *map, size_t key_sz,
+			   size_t value_sz, bool check_value_sz)
+{
+	if (map->fd <= 0)
+		return -ENOENT;
+
+	if (map->def.key_size != key_sz) {
+		pr_warn("map '%s': unexpected key size %zu provided, expected %u\n",
+			map->name, key_sz, map->def.key_size);
+		return -EINVAL;
+	}
+
+	if (!check_value_sz)
+		return 0;
+
+	switch (map->def.type) {
+	case BPF_MAP_TYPE_PERCPU_ARRAY:
+	case BPF_MAP_TYPE_PERCPU_HASH:
+	case BPF_MAP_TYPE_LRU_PERCPU_HASH:
+	case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE: {
+		int num_cpu = libbpf_num_possible_cpus();
+		size_t elem_sz = roundup(map->def.value_size, 8);
+
+		if (value_sz != num_cpu * elem_sz) {
+			pr_warn("map '%s': unexpected value size %zu provided for per-CPU map, expected %d * %zu = %zd\n",
+				map->name, value_sz, num_cpu, elem_sz, num_cpu * elem_sz);
+			return -EINVAL;
+		}
+		break;
+	}
+	default:
+		if (map->def.value_size != value_sz) {
+			pr_warn("map '%s': unexpected value size %zu provided, expected %u\n",
+				map->name, value_sz, map->def.value_size);
+			return -EINVAL;
+		}
+		break;
+	}
+	return 0;
+}
+
+int bpf_map__lookup_elem(const struct bpf_map *map,
+			 const void *key, size_t key_sz,
+			 void *value, size_t value_sz, __u64 flags)
+{
+	int err;
+
+	err = validate_map_op(map, key_sz, value_sz, true);
+	if (err)
+		return libbpf_err(err);
+
+	return bpf_map_lookup_elem_flags(map->fd, key, value, flags);
+}
+
+int bpf_map__update_elem(const struct bpf_map *map,
+			 const void *key, size_t key_sz,
+			 const void *value, size_t value_sz, __u64 flags)
+{
+	int err;
+
+	err = validate_map_op(map, key_sz, value_sz, true);
+	if (err)
+		return libbpf_err(err);
+
+	return bpf_map_update_elem(map->fd, key, value, flags);
+}
+
+int bpf_map__delete_elem(const struct bpf_map *map,
+			 const void *key, size_t key_sz, __u64 flags)
+{
+	int err;
+
+	err = validate_map_op(map, key_sz, 0, false /* check_value_sz */);
+	if (err)
+		return libbpf_err(err);
+
+	return bpf_map_delete_elem_flags(map->fd, key, flags);
+}
+
+int bpf_map__lookup_and_delete_elem(const struct bpf_map *map,
+				    const void *key, size_t key_sz,
+				    void *value, size_t value_sz, __u64 flags)
+{
+	int err;
+
+	err = validate_map_op(map, key_sz, value_sz, true);
+	if (err)
+		return libbpf_err(err);
+
+	return bpf_map_lookup_and_delete_elem_flags(map->fd, key, value, flags);
+}
+
+int bpf_map__get_next_key(const struct bpf_map *map,
+			  const void *cur_key, void *next_key, size_t key_sz)
+{
+	int err;
+
+	err = validate_map_op(map, key_sz, 0, false /* check_value_sz */);
+	if (err)
+		return libbpf_err(err);
+
+	return bpf_map_get_next_key(map->fd, cur_key, next_key);
+}
+
+long libbpf_get_error(const void *ptr)
+{
+	if (!IS_ERR_OR_NULL(ptr))
+		return 0;
+
+	if (IS_ERR(ptr))
+		errno = -PTR_ERR(ptr);
+
+	/* If ptr == NULL, then errno should be already set by the failing
+	 * API, because libbpf never returns NULL on success and it now always
+	 * sets errno on error. So no extra errno handling for ptr == NULL
+	 * case.
+	 */
+	return -errno;
+}
+
+/* Replace link's underlying BPF program with the new one */
+int bpf_link__update_program(struct bpf_link *link, struct bpf_program *prog)
+{
+	int ret;
+
+	ret = bpf_link_update(bpf_link__fd(link), bpf_program__fd(prog), NULL);
+	return libbpf_err_errno(ret);
+}
+
+/* Release "ownership" of underlying BPF resource (typically, BPF program
+ * attached to some BPF hook, e.g., tracepoint, kprobe, etc). Disconnected
+ * link, when destructed through bpf_link__destroy() call won't attempt to
+ * detach/unregisted that BPF resource. This is useful in situations where,
+ * say, attached BPF program has to outlive userspace program that attached it
+ * in the system. Depending on type of BPF program, though, there might be
+ * additional steps (like pinning BPF program in BPF FS) necessary to ensure
+ * exit of userspace program doesn't trigger automatic detachment and clean up
+ * inside the kernel.
+ */
+void bpf_link__disconnect(struct bpf_link *link)
+{
+	link->disconnected = true;
+}
+
+int bpf_link__destroy(struct bpf_link *link)
+{
+	int err = 0;
+
+	if (IS_ERR_OR_NULL(link))
+		return 0;
+
+	if (!link->disconnected && link->detach)
+		err = link->detach(link);
+	if (link->pin_path)
+		free(link->pin_path);
+	if (link->dealloc)
+		link->dealloc(link);
+	else
+		free(link);
+
+	return libbpf_err(err);
+}
+
+int bpf_link__fd(const struct bpf_link *link)
+{
+	return link->fd;
+}
+
+const char *bpf_link__pin_path(const struct bpf_link *link)
+{
+	return link->pin_path;
+}
+
+static int bpf_link__detach_fd(struct bpf_link *link)
+{
+	return libbpf_err_errno(close(link->fd));
+}
+
+struct bpf_link *bpf_link__open(const char *path)
+{
+	struct bpf_link *link;
+	int fd;
+
+	fd = bpf_obj_get(path);
+	if (fd < 0) {
+		fd = -errno;
+		pr_warn("failed to open link at %s: %d\n", path, fd);
+		return libbpf_err_ptr(fd);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link) {
+		close(fd);
+		return libbpf_err_ptr(-ENOMEM);
+	}
+	link->detach = &bpf_link__detach_fd;
+	link->fd = fd;
+
+	link->pin_path = strdup(path);
+	if (!link->pin_path) {
+		bpf_link__destroy(link);
+		return libbpf_err_ptr(-ENOMEM);
+	}
+
+	return link;
+}
+
+int bpf_link__detach(struct bpf_link *link)
+{
+	return bpf_link_detach(link->fd) ? -errno : 0;
+}
+
+int bpf_link__pin(struct bpf_link *link, const char *path)
+{
+	int err;
+
+	if (link->pin_path)
+		return libbpf_err(-EBUSY);
+	err = make_parent_dir(path);
+	if (err)
+		return libbpf_err(err);
+	err = check_path(path);
+	if (err)
+		return libbpf_err(err);
+
+	link->pin_path = strdup(path);
+	if (!link->pin_path)
+		return libbpf_err(-ENOMEM);
+
+	if (bpf_obj_pin(link->fd, link->pin_path)) {
+		err = -errno;
+		zfree(&link->pin_path);
+		return libbpf_err(err);
+	}
+
+	pr_debug("link fd=%d: pinned at %s\n", link->fd, link->pin_path);
+	return 0;
+}
+
+int bpf_link__unpin(struct bpf_link *link)
+{
+	int err;
+
+	if (!link->pin_path)
+		return libbpf_err(-EINVAL);
+
+	err = unlink(link->pin_path);
+	if (err != 0)
+		return -errno;
+
+	pr_debug("link fd=%d: unpinned from %s\n", link->fd, link->pin_path);
+	zfree(&link->pin_path);
+	return 0;
+}
+
+struct bpf_link_perf {
+	struct bpf_link link;
+	int perf_event_fd;
+	/* legacy kprobe support: keep track of probe identifier and type */
+	char *legacy_probe_name;
+	bool legacy_is_kprobe;
+	bool legacy_is_retprobe;
+};
+
+static int remove_kprobe_event_legacy(const char *probe_name, bool retprobe);
+static int remove_uprobe_event_legacy(const char *probe_name, bool retprobe);
+
+static int bpf_link_perf_detach(struct bpf_link *link)
+{
+	struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
+	int err = 0;
+
+	if (ioctl(perf_link->perf_event_fd, PERF_EVENT_IOC_DISABLE, 0) < 0)
+		err = -errno;
+
+	if (perf_link->perf_event_fd != link->fd)
+		close(perf_link->perf_event_fd);
+	close(link->fd);
+
+	/* legacy uprobe/kprobe needs to be removed after perf event fd closure */
+	if (perf_link->legacy_probe_name) {
+		if (perf_link->legacy_is_kprobe) {
+			err = remove_kprobe_event_legacy(perf_link->legacy_probe_name,
+							 perf_link->legacy_is_retprobe);
+		} else {
+			err = remove_uprobe_event_legacy(perf_link->legacy_probe_name,
+							 perf_link->legacy_is_retprobe);
+		}
+	}
+
+	return err;
+}
+
+static void bpf_link_perf_dealloc(struct bpf_link *link)
+{
+	struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
+
+	free(perf_link->legacy_probe_name);
+	free(perf_link);
+}
+
+struct bpf_link *bpf_program__attach_perf_event_opts(const struct bpf_program *prog, int pfd,
+						     const struct bpf_perf_event_opts *opts)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link_perf *link;
+	int prog_fd, link_fd = -1, err;
+
+	if (!OPTS_VALID(opts, bpf_perf_event_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	if (pfd < 0) {
+		pr_warn("prog '%s': invalid perf event FD %d\n",
+			prog->name, pfd);
+		return libbpf_err_ptr(-EINVAL);
+	}
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("prog '%s': can't attach BPF program w/o FD (did you load it?)\n",
+			prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->link.detach = &bpf_link_perf_detach;
+	link->link.dealloc = &bpf_link_perf_dealloc;
+	link->perf_event_fd = pfd;
+
+	if (kernel_supports(prog->obj, FEAT_PERF_LINK)) {
+		DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_opts,
+			.perf_event.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0));
+
+		link_fd = bpf_link_create(prog_fd, pfd, BPF_PERF_EVENT, &link_opts);
+		if (link_fd < 0) {
+			err = -errno;
+			pr_warn("prog '%s': failed to create BPF link for perf_event FD %d: %d (%s)\n",
+				prog->name, pfd,
+				err, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+			goto err_out;
+		}
+		link->link.fd = link_fd;
+	} else {
+		if (OPTS_GET(opts, bpf_cookie, 0)) {
+			pr_warn("prog '%s': user context value is not supported\n", prog->name);
+			err = -EOPNOTSUPP;
+			goto err_out;
+		}
+
+		if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
+			err = -errno;
+			pr_warn("prog '%s': failed to attach to perf_event FD %d: %s\n",
+				prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+			if (err == -EPROTO)
+				pr_warn("prog '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n",
+					prog->name, pfd);
+			goto err_out;
+		}
+		link->link.fd = pfd;
+	}
+	if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
+		err = -errno;
+		pr_warn("prog '%s': failed to enable perf_event FD %d: %s\n",
+			prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_out;
+	}
+
+	return &link->link;
+err_out:
+	if (link_fd >= 0)
+		close(link_fd);
+	free(link);
+	return libbpf_err_ptr(err);
+}
+
+struct bpf_link *bpf_program__attach_perf_event(const struct bpf_program *prog, int pfd)
+{
+	return bpf_program__attach_perf_event_opts(prog, pfd, NULL);
+}
+
+/*
+ * this function is expected to parse integer in the range of [0, 2^31-1] from
+ * given file using scanf format string fmt. If actual parsed value is
+ * negative, the result might be indistinguishable from error
+ */
+static int parse_uint_from_file(const char *file, const char *fmt)
+{
+	char buf[STRERR_BUFSIZE];
+	int err, ret;
+	FILE *f;
+
+	f = fopen(file, "r");
+	if (!f) {
+		err = -errno;
+		pr_debug("failed to open '%s': %s\n", file,
+			 libbpf_strerror_r(err, buf, sizeof(buf)));
+		return err;
+	}
+	err = fscanf(f, fmt, &ret);
+	if (err != 1) {
+		err = err == EOF ? -EIO : -errno;
+		pr_debug("failed to parse '%s': %s\n", file,
+			libbpf_strerror_r(err, buf, sizeof(buf)));
+		fclose(f);
+		return err;
+	}
+	fclose(f);
+	return ret;
+}
+
+static int determine_kprobe_perf_type(void)
+{
+	const char *file = "/sys/bus/event_source/devices/kprobe/type";
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int determine_uprobe_perf_type(void)
+{
+	const char *file = "/sys/bus/event_source/devices/uprobe/type";
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int determine_kprobe_retprobe_bit(void)
+{
+	const char *file = "/sys/bus/event_source/devices/kprobe/format/retprobe";
+
+	return parse_uint_from_file(file, "config:%d\n");
+}
+
+static int determine_uprobe_retprobe_bit(void)
+{
+	const char *file = "/sys/bus/event_source/devices/uprobe/format/retprobe";
+
+	return parse_uint_from_file(file, "config:%d\n");
+}
+
+#define PERF_UPROBE_REF_CTR_OFFSET_BITS 32
+#define PERF_UPROBE_REF_CTR_OFFSET_SHIFT 32
+
+static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
+				 uint64_t offset, int pid, size_t ref_ctr_off)
+{
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_event_attr attr;
+	char errmsg[STRERR_BUFSIZE];
+	int type, pfd;
+
+	if (ref_ctr_off >= (1ULL << PERF_UPROBE_REF_CTR_OFFSET_BITS))
+		return -EINVAL;
+
+	memset(&attr, 0, attr_sz);
+
+	type = uprobe ? determine_uprobe_perf_type()
+		      : determine_kprobe_perf_type();
+	if (type < 0) {
+		pr_warn("failed to determine %s perf type: %s\n",
+			uprobe ? "uprobe" : "kprobe",
+			libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
+		return type;
+	}
+	if (retprobe) {
+		int bit = uprobe ? determine_uprobe_retprobe_bit()
+				 : determine_kprobe_retprobe_bit();
+
+		if (bit < 0) {
+			pr_warn("failed to determine %s retprobe bit: %s\n",
+				uprobe ? "uprobe" : "kprobe",
+				libbpf_strerror_r(bit, errmsg, sizeof(errmsg)));
+			return bit;
+		}
+		attr.config |= 1 << bit;
+	}
+	attr.size = attr_sz;
+	attr.type = type;
+	attr.config |= (__u64)ref_ctr_off << PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
+	attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */
+	attr.config2 = offset;		 /* kprobe_addr or probe_offset */
+
+	/* pid filter is meaningful only for uprobes */
+	pfd = syscall(__NR_perf_event_open, &attr,
+		      pid < 0 ? -1 : pid /* pid */,
+		      pid == -1 ? 0 : -1 /* cpu */,
+		      -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
+	return pfd >= 0 ? pfd : -errno;
+}
+
+static int append_to_file(const char *file, const char *fmt, ...)
+{
+	int fd, n, err = 0;
+	va_list ap;
+
+	fd = open(file, O_WRONLY | O_APPEND | O_CLOEXEC, 0);
+	if (fd < 0)
+		return -errno;
+
+	va_start(ap, fmt);
+	n = vdprintf(fd, fmt, ap);
+	va_end(ap);
+
+	if (n < 0)
+		err = -errno;
+
+	close(fd);
+	return err;
+}
+
+#define DEBUGFS "/sys/kernel/debug/tracing"
+#define TRACEFS "/sys/kernel/tracing"
+
+static bool use_debugfs(void)
+{
+	static int has_debugfs = -1;
+
+	if (has_debugfs < 0)
+		has_debugfs = faccessat(AT_FDCWD, DEBUGFS, F_OK, AT_EACCESS) == 0;
+
+	return has_debugfs == 1;
+}
+
+static const char *tracefs_path(void)
+{
+	return use_debugfs() ? DEBUGFS : TRACEFS;
+}
+
+static const char *tracefs_kprobe_events(void)
+{
+	return use_debugfs() ? DEBUGFS"/kprobe_events" : TRACEFS"/kprobe_events";
+}
+
+static const char *tracefs_uprobe_events(void)
+{
+	return use_debugfs() ? DEBUGFS"/uprobe_events" : TRACEFS"/uprobe_events";
+}
+
+static void gen_kprobe_legacy_event_name(char *buf, size_t buf_sz,
+					 const char *kfunc_name, size_t offset)
+{
+	static int index = 0;
+
+	snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx_%d", getpid(), kfunc_name, offset,
+		 __sync_fetch_and_add(&index, 1));
+}
+
+static int add_kprobe_event_legacy(const char *probe_name, bool retprobe,
+				   const char *kfunc_name, size_t offset)
+{
+	return append_to_file(tracefs_kprobe_events(), "%c:%s/%s %s+0x%zx",
+			      retprobe ? 'r' : 'p',
+			      retprobe ? "kretprobes" : "kprobes",
+			      probe_name, kfunc_name, offset);
+}
+
+static int remove_kprobe_event_legacy(const char *probe_name, bool retprobe)
+{
+	return append_to_file(tracefs_kprobe_events(), "-:%s/%s",
+			      retprobe ? "kretprobes" : "kprobes", probe_name);
+}
+
+static int determine_kprobe_perf_type_legacy(const char *probe_name, bool retprobe)
+{
+	char file[256];
+
+	snprintf(file, sizeof(file), "%s/events/%s/%s/id",
+		 tracefs_path(), retprobe ? "kretprobes" : "kprobes", probe_name);
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int perf_event_kprobe_open_legacy(const char *probe_name, bool retprobe,
+					 const char *kfunc_name, size_t offset, int pid)
+{
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_event_attr attr;
+	char errmsg[STRERR_BUFSIZE];
+	int type, pfd, err;
+
+	err = add_kprobe_event_legacy(probe_name, retprobe, kfunc_name, offset);
+	if (err < 0) {
+		pr_warn("failed to add legacy kprobe event for '%s+0x%zx': %s\n",
+			kfunc_name, offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return err;
+	}
+	type = determine_kprobe_perf_type_legacy(probe_name, retprobe);
+	if (type < 0) {
+		err = type;
+		pr_warn("failed to determine legacy kprobe event id for '%s+0x%zx': %s\n",
+			kfunc_name, offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_clean_legacy;
+	}
+
+	memset(&attr, 0, attr_sz);
+	attr.size = attr_sz;
+	attr.config = type;
+	attr.type = PERF_TYPE_TRACEPOINT;
+
+	pfd = syscall(__NR_perf_event_open, &attr,
+		      pid < 0 ? -1 : pid, /* pid */
+		      pid == -1 ? 0 : -1, /* cpu */
+		      -1 /* group_fd */,  PERF_FLAG_FD_CLOEXEC);
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("legacy kprobe perf_event_open() failed: %s\n",
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_clean_legacy;
+	}
+	return pfd;
+
+err_clean_legacy:
+	/* Clear the newly added legacy kprobe_event */
+	remove_kprobe_event_legacy(probe_name, retprobe);
+	return err;
+}
+
+static const char *arch_specific_syscall_pfx(void)
+{
+#if defined(__x86_64__)
+	return "x64";
+#elif defined(__i386__)
+	return "ia32";
+#elif defined(__s390x__)
+	return "s390x";
+#elif defined(__s390__)
+	return "s390";
+#elif defined(__arm__)
+	return "arm";
+#elif defined(__aarch64__)
+	return "arm64";
+#elif defined(__mips__)
+	return "mips";
+#elif defined(__riscv)
+	return "riscv";
+#elif defined(__powerpc__)
+	return "powerpc";
+#elif defined(__powerpc64__)
+	return "powerpc64";
+#else
+	return NULL;
+#endif
+}
+
+static int probe_kern_syscall_wrapper(void)
+{
+	char syscall_name[64];
+	const char *ksys_pfx;
+
+	ksys_pfx = arch_specific_syscall_pfx();
+	if (!ksys_pfx)
+		return 0;
+
+	snprintf(syscall_name, sizeof(syscall_name), "__%s_sys_bpf", ksys_pfx);
+
+	if (determine_kprobe_perf_type() >= 0) {
+		int pfd;
+
+		pfd = perf_event_open_probe(false, false, syscall_name, 0, getpid(), 0);
+		if (pfd >= 0)
+			close(pfd);
+
+		return pfd >= 0 ? 1 : 0;
+	} else { /* legacy mode */
+		char probe_name[128];
+
+		gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name), syscall_name, 0);
+		if (add_kprobe_event_legacy(probe_name, false, syscall_name, 0) < 0)
+			return 0;
+
+		(void)remove_kprobe_event_legacy(probe_name, false);
+		return 1;
+	}
+}
+
+struct bpf_link *
+bpf_program__attach_kprobe_opts(const struct bpf_program *prog,
+				const char *func_name,
+				const struct bpf_kprobe_opts *opts)
+{
+	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
+	char errmsg[STRERR_BUFSIZE];
+	char *legacy_probe = NULL;
+	struct bpf_link *link;
+	size_t offset;
+	bool retprobe, legacy;
+	int pfd, err;
+
+	if (!OPTS_VALID(opts, bpf_kprobe_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	retprobe = OPTS_GET(opts, retprobe, false);
+	offset = OPTS_GET(opts, offset, 0);
+	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+
+	legacy = determine_kprobe_perf_type() < 0;
+	if (!legacy) {
+		pfd = perf_event_open_probe(false /* uprobe */, retprobe,
+					    func_name, offset,
+					    -1 /* pid */, 0 /* ref_ctr_off */);
+	} else {
+		char probe_name[256];
+
+		gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name),
+					     func_name, offset);
+
+		legacy_probe = strdup(probe_name);
+		if (!legacy_probe)
+			return libbpf_err_ptr(-ENOMEM);
+
+		pfd = perf_event_kprobe_open_legacy(legacy_probe, retprobe, func_name,
+						    offset, -1 /* pid */);
+	}
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("prog '%s': failed to create %s '%s+0x%zx' perf event: %s\n",
+			prog->name, retprobe ? "kretprobe" : "kprobe",
+			func_name, offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_out;
+	}
+	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
+	err = libbpf_get_error(link);
+	if (err) {
+		close(pfd);
+		pr_warn("prog '%s': failed to attach to %s '%s+0x%zx': %s\n",
+			prog->name, retprobe ? "kretprobe" : "kprobe",
+			func_name, offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_clean_legacy;
+	}
+	if (legacy) {
+		struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
+
+		perf_link->legacy_probe_name = legacy_probe;
+		perf_link->legacy_is_kprobe = true;
+		perf_link->legacy_is_retprobe = retprobe;
+	}
+
+	return link;
+
+err_clean_legacy:
+	if (legacy)
+		remove_kprobe_event_legacy(legacy_probe, retprobe);
+err_out:
+	free(legacy_probe);
+	return libbpf_err_ptr(err);
+}
+
+struct bpf_link *bpf_program__attach_kprobe(const struct bpf_program *prog,
+					    bool retprobe,
+					    const char *func_name)
+{
+	DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts,
+		.retprobe = retprobe,
+	);
+
+	return bpf_program__attach_kprobe_opts(prog, func_name, &opts);
+}
+
+struct bpf_link *bpf_program__attach_ksyscall(const struct bpf_program *prog,
+					      const char *syscall_name,
+					      const struct bpf_ksyscall_opts *opts)
+{
+	LIBBPF_OPTS(bpf_kprobe_opts, kprobe_opts);
+	char func_name[128];
+
+	if (!OPTS_VALID(opts, bpf_ksyscall_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	if (kernel_supports(prog->obj, FEAT_SYSCALL_WRAPPER)) {
+		/* arch_specific_syscall_pfx() should never return NULL here
+		 * because it is guarded by kernel_supports(). However, since
+		 * compiler does not know that we have an explicit conditional
+		 * as well.
+		 */
+		snprintf(func_name, sizeof(func_name), "__%s_sys_%s",
+			 arch_specific_syscall_pfx() ? : "", syscall_name);
+	} else {
+		snprintf(func_name, sizeof(func_name), "__se_sys_%s", syscall_name);
+	}
+
+	kprobe_opts.retprobe = OPTS_GET(opts, retprobe, false);
+	kprobe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+
+	return bpf_program__attach_kprobe_opts(prog, func_name, &kprobe_opts);
+}
+
+/* Adapted from perf/util/string.c */
+static bool glob_match(const char *str, const char *pat)
+{
+	while (*str && *pat && *pat != '*') {
+		if (*pat == '?') {      /* Matches any single character */
+			str++;
+			pat++;
+			continue;
+		}
+		if (*str != *pat)
+			return false;
+		str++;
+		pat++;
+	}
+	/* Check wild card */
+	if (*pat == '*') {
+		while (*pat == '*')
+			pat++;
+		if (!*pat) /* Tail wild card matches all */
+			return true;
+		while (*str)
+			if (glob_match(str++, pat))
+				return true;
+	}
+	return !*str && !*pat;
+}
+
+struct kprobe_multi_resolve {
+	const char *pattern;
+	unsigned long *addrs;
+	size_t cap;
+	size_t cnt;
+};
+
+static int
+resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type,
+			const char *sym_name, void *ctx)
+{
+	struct kprobe_multi_resolve *res = ctx;
+	int err;
+
+	if (!glob_match(sym_name, res->pattern))
+		return 0;
+
+	err = libbpf_ensure_mem((void **) &res->addrs, &res->cap, sizeof(unsigned long),
+				res->cnt + 1);
+	if (err)
+		return err;
+
+	res->addrs[res->cnt++] = (unsigned long) sym_addr;
+	return 0;
+}
+
+struct bpf_link *
+bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
+				      const char *pattern,
+				      const struct bpf_kprobe_multi_opts *opts)
+{
+	LIBBPF_OPTS(bpf_link_create_opts, lopts);
+	struct kprobe_multi_resolve res = {
+		.pattern = pattern,
+	};
+	struct bpf_link *link = NULL;
+	char errmsg[STRERR_BUFSIZE];
+	const unsigned long *addrs;
+	int err, link_fd, prog_fd;
+	const __u64 *cookies;
+	const char **syms;
+	bool retprobe;
+	size_t cnt;
+
+	if (!OPTS_VALID(opts, bpf_kprobe_multi_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	syms    = OPTS_GET(opts, syms, false);
+	addrs   = OPTS_GET(opts, addrs, false);
+	cnt     = OPTS_GET(opts, cnt, false);
+	cookies = OPTS_GET(opts, cookies, false);
+
+	if (!pattern && !addrs && !syms)
+		return libbpf_err_ptr(-EINVAL);
+	if (pattern && (addrs || syms || cookies || cnt))
+		return libbpf_err_ptr(-EINVAL);
+	if (!pattern && !cnt)
+		return libbpf_err_ptr(-EINVAL);
+	if (addrs && syms)
+		return libbpf_err_ptr(-EINVAL);
+
+	if (pattern) {
+		err = libbpf_kallsyms_parse(resolve_kprobe_multi_cb, &res);
+		if (err)
+			goto error;
+		if (!res.cnt) {
+			err = -ENOENT;
+			goto error;
+		}
+		addrs = res.addrs;
+		cnt = res.cnt;
+	}
+
+	retprobe = OPTS_GET(opts, retprobe, false);
+
+	lopts.kprobe_multi.syms = syms;
+	lopts.kprobe_multi.addrs = addrs;
+	lopts.kprobe_multi.cookies = cookies;
+	lopts.kprobe_multi.cnt = cnt;
+	lopts.kprobe_multi.flags = retprobe ? BPF_F_KPROBE_MULTI_RETURN : 0;
+
+	link = calloc(1, sizeof(*link));
+	if (!link) {
+		err = -ENOMEM;
+		goto error;
+	}
+	link->detach = &bpf_link__detach_fd;
+
+	prog_fd = bpf_program__fd(prog);
+	link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_KPROBE_MULTI, &lopts);
+	if (link_fd < 0) {
+		err = -errno;
+		pr_warn("prog '%s': failed to attach: %s\n",
+			prog->name, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto error;
+	}
+	link->fd = link_fd;
+	free(res.addrs);
+	return link;
+
+error:
+	free(link);
+	free(res.addrs);
+	return libbpf_err_ptr(err);
+}
+
+static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts);
+	unsigned long offset = 0;
+	const char *func_name;
+	char *func;
+	int n;
+
+	*link = NULL;
+
+	/* no auto-attach for SEC("kprobe") and SEC("kretprobe") */
+	if (strcmp(prog->sec_name, "kprobe") == 0 || strcmp(prog->sec_name, "kretprobe") == 0)
+		return 0;
+
+	opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe/");
+	if (opts.retprobe)
+		func_name = prog->sec_name + sizeof("kretprobe/") - 1;
+	else
+		func_name = prog->sec_name + sizeof("kprobe/") - 1;
+
+	n = sscanf(func_name, "%m[a-zA-Z0-9_.]+%li", &func, &offset);
+	if (n < 1) {
+		pr_warn("kprobe name is invalid: %s\n", func_name);
+		return -EINVAL;
+	}
+	if (opts.retprobe && offset != 0) {
+		free(func);
+		pr_warn("kretprobes do not support offset specification\n");
+		return -EINVAL;
+	}
+
+	opts.offset = offset;
+	*link = bpf_program__attach_kprobe_opts(prog, func, &opts);
+	free(func);
+	return libbpf_get_error(*link);
+}
+
+static int attach_ksyscall(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	LIBBPF_OPTS(bpf_ksyscall_opts, opts);
+	const char *syscall_name;
+
+	*link = NULL;
+
+	/* no auto-attach for SEC("ksyscall") and SEC("kretsyscall") */
+	if (strcmp(prog->sec_name, "ksyscall") == 0 || strcmp(prog->sec_name, "kretsyscall") == 0)
+		return 0;
+
+	opts.retprobe = str_has_pfx(prog->sec_name, "kretsyscall/");
+	if (opts.retprobe)
+		syscall_name = prog->sec_name + sizeof("kretsyscall/") - 1;
+	else
+		syscall_name = prog->sec_name + sizeof("ksyscall/") - 1;
+
+	*link = bpf_program__attach_ksyscall(prog, syscall_name, &opts);
+	return *link ? 0 : -errno;
+}
+
+static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
+	const char *spec;
+	char *pattern;
+	int n;
+
+	*link = NULL;
+
+	/* no auto-attach for SEC("kprobe.multi") and SEC("kretprobe.multi") */
+	if (strcmp(prog->sec_name, "kprobe.multi") == 0 ||
+	    strcmp(prog->sec_name, "kretprobe.multi") == 0)
+		return 0;
+
+	opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe.multi/");
+	if (opts.retprobe)
+		spec = prog->sec_name + sizeof("kretprobe.multi/") - 1;
+	else
+		spec = prog->sec_name + sizeof("kprobe.multi/") - 1;
+
+	n = sscanf(spec, "%m[a-zA-Z0-9_.*?]", &pattern);
+	if (n < 1) {
+		pr_warn("kprobe multi pattern is invalid: %s\n", pattern);
+		return -EINVAL;
+	}
+
+	*link = bpf_program__attach_kprobe_multi_opts(prog, pattern, &opts);
+	free(pattern);
+	return libbpf_get_error(*link);
+}
+
+static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
+					 const char *binary_path, uint64_t offset)
+{
+	int i;
+
+	snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx", getpid(), binary_path, (size_t)offset);
+
+	/* sanitize binary_path in the probe name */
+	for (i = 0; buf[i]; i++) {
+		if (!isalnum(buf[i]))
+			buf[i] = '_';
+	}
+}
+
+static inline int add_uprobe_event_legacy(const char *probe_name, bool retprobe,
+					  const char *binary_path, size_t offset)
+{
+	return append_to_file(tracefs_uprobe_events(), "%c:%s/%s %s:0x%zx",
+			      retprobe ? 'r' : 'p',
+			      retprobe ? "uretprobes" : "uprobes",
+			      probe_name, binary_path, offset);
+}
+
+static inline int remove_uprobe_event_legacy(const char *probe_name, bool retprobe)
+{
+	return append_to_file(tracefs_uprobe_events(), "-:%s/%s",
+			      retprobe ? "uretprobes" : "uprobes", probe_name);
+}
+
+static int determine_uprobe_perf_type_legacy(const char *probe_name, bool retprobe)
+{
+	char file[512];
+
+	snprintf(file, sizeof(file), "%s/events/%s/%s/id",
+		 tracefs_path(), retprobe ? "uretprobes" : "uprobes", probe_name);
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
+					 const char *binary_path, size_t offset, int pid)
+{
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_event_attr attr;
+	int type, pfd, err;
+
+	err = add_uprobe_event_legacy(probe_name, retprobe, binary_path, offset);
+	if (err < 0) {
+		pr_warn("failed to add legacy uprobe event for %s:0x%zx: %d\n",
+			binary_path, (size_t)offset, err);
+		return err;
+	}
+	type = determine_uprobe_perf_type_legacy(probe_name, retprobe);
+	if (type < 0) {
+		err = type;
+		pr_warn("failed to determine legacy uprobe event id for %s:0x%zx: %d\n",
+			binary_path, offset, err);
+		goto err_clean_legacy;
+	}
+
+	memset(&attr, 0, attr_sz);
+	attr.size = attr_sz;
+	attr.config = type;
+	attr.type = PERF_TYPE_TRACEPOINT;
+
+	pfd = syscall(__NR_perf_event_open, &attr,
+		      pid < 0 ? -1 : pid, /* pid */
+		      pid == -1 ? 0 : -1, /* cpu */
+		      -1 /* group_fd */,  PERF_FLAG_FD_CLOEXEC);
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("legacy uprobe perf_event_open() failed: %d\n", err);
+		goto err_clean_legacy;
+	}
+	return pfd;
+
+err_clean_legacy:
+	/* Clear the newly added legacy uprobe_event */
+	remove_uprobe_event_legacy(probe_name, retprobe);
+	return err;
+}
+
+/* Return next ELF section of sh_type after scn, or first of that type if scn is NULL. */
+static Elf_Scn *elf_find_next_scn_by_type(Elf *elf, int sh_type, Elf_Scn *scn)
+{
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		GElf_Shdr sh;
+
+		if (!gelf_getshdr(scn, &sh))
+			continue;
+		if (sh.sh_type == sh_type)
+			return scn;
+	}
+	return NULL;
+}
+
+/* Find offset of function name in object specified by path.  "name" matches
+ * symbol name or name@@LIB for library functions.
+ */
+static long elf_find_func_offset(const char *binary_path, const char *name)
+{
+	int fd, i, sh_types[2] = { SHT_DYNSYM, SHT_SYMTAB };
+	bool is_shared_lib, is_name_qualified;
+	char errmsg[STRERR_BUFSIZE];
+	long ret = -ENOENT;
+	size_t name_len;
+	GElf_Ehdr ehdr;
+	Elf *elf;
+
+	fd = open(binary_path, O_RDONLY | O_CLOEXEC);
+	if (fd < 0) {
+		ret = -errno;
+		pr_warn("failed to open %s: %s\n", binary_path,
+			libbpf_strerror_r(ret, errmsg, sizeof(errmsg)));
+		return ret;
+	}
+	elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+	if (!elf) {
+		pr_warn("elf: could not read elf from %s: %s\n", binary_path, elf_errmsg(-1));
+		close(fd);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	if (!gelf_getehdr(elf, &ehdr)) {
+		pr_warn("elf: failed to get ehdr from %s: %s\n", binary_path, elf_errmsg(-1));
+		ret = -LIBBPF_ERRNO__FORMAT;
+		goto out;
+	}
+	/* for shared lib case, we do not need to calculate relative offset */
+	is_shared_lib = ehdr.e_type == ET_DYN;
+
+	name_len = strlen(name);
+	/* Does name specify "@@LIB"? */
+	is_name_qualified = strstr(name, "@@") != NULL;
+
+	/* Search SHT_DYNSYM, SHT_SYMTAB for symbol.  This search order is used because if
+	 * a binary is stripped, it may only have SHT_DYNSYM, and a fully-statically
+	 * linked binary may not have SHT_DYMSYM, so absence of a section should not be
+	 * reported as a warning/error.
+	 */
+	for (i = 0; i < ARRAY_SIZE(sh_types); i++) {
+		size_t nr_syms, strtabidx, idx;
+		Elf_Data *symbols = NULL;
+		Elf_Scn *scn = NULL;
+		int last_bind = -1;
+		const char *sname;
+		GElf_Shdr sh;
+
+		scn = elf_find_next_scn_by_type(elf, sh_types[i], NULL);
+		if (!scn) {
+			pr_debug("elf: failed to find symbol table ELF sections in '%s'\n",
+				 binary_path);
+			continue;
+		}
+		if (!gelf_getshdr(scn, &sh))
+			continue;
+		strtabidx = sh.sh_link;
+		symbols = elf_getdata(scn, 0);
+		if (!symbols) {
+			pr_warn("elf: failed to get symbols for symtab section in '%s': %s\n",
+				binary_path, elf_errmsg(-1));
+			ret = -LIBBPF_ERRNO__FORMAT;
+			goto out;
+		}
+		nr_syms = symbols->d_size / sh.sh_entsize;
+
+		for (idx = 0; idx < nr_syms; idx++) {
+			int curr_bind;
+			GElf_Sym sym;
+			Elf_Scn *sym_scn;
+			GElf_Shdr sym_sh;
+
+			if (!gelf_getsym(symbols, idx, &sym))
+				continue;
+
+			if (GELF_ST_TYPE(sym.st_info) != STT_FUNC)
+				continue;
+
+			sname = elf_strptr(elf, strtabidx, sym.st_name);
+			if (!sname)
+				continue;
+
+			curr_bind = GELF_ST_BIND(sym.st_info);
+
+			/* User can specify func, func@@LIB or func@@LIB_VERSION. */
+			if (strncmp(sname, name, name_len) != 0)
+				continue;
+			/* ...but we don't want a search for "foo" to match 'foo2" also, so any
+			 * additional characters in sname should be of the form "@@LIB".
+			 */
+			if (!is_name_qualified && sname[name_len] != '\0' && sname[name_len] != '@')
+				continue;
+
+			if (ret >= 0) {
+				/* handle multiple matches */
+				if (last_bind != STB_WEAK && curr_bind != STB_WEAK) {
+					/* Only accept one non-weak bind. */
+					pr_warn("elf: ambiguous match for '%s', '%s' in '%s'\n",
+						sname, name, binary_path);
+					ret = -LIBBPF_ERRNO__FORMAT;
+					goto out;
+				} else if (curr_bind == STB_WEAK) {
+					/* already have a non-weak bind, and
+					 * this is a weak bind, so ignore.
+					 */
+					continue;
+				}
+			}
+
+			/* Transform symbol's virtual address (absolute for
+			 * binaries and relative for shared libs) into file
+			 * offset, which is what kernel is expecting for
+			 * uprobe/uretprobe attachment.
+			 * See Documentation/trace/uprobetracer.rst for more
+			 * details.
+			 * This is done by looking up symbol's containing
+			 * section's header and using it's virtual address
+			 * (sh_addr) and corresponding file offset (sh_offset)
+			 * to transform sym.st_value (virtual address) into
+			 * desired final file offset.
+			 */
+			sym_scn = elf_getscn(elf, sym.st_shndx);
+			if (!sym_scn)
+				continue;
+			if (!gelf_getshdr(sym_scn, &sym_sh))
+				continue;
+
+			ret = sym.st_value - sym_sh.sh_addr + sym_sh.sh_offset;
+			last_bind = curr_bind;
+		}
+		if (ret > 0)
+			break;
+	}
+
+	if (ret > 0) {
+		pr_debug("elf: symbol address match for '%s' in '%s': 0x%lx\n", name, binary_path,
+			 ret);
+	} else {
+		if (ret == 0) {
+			pr_warn("elf: '%s' is 0 in symtab for '%s': %s\n", name, binary_path,
+				is_shared_lib ? "should not be 0 in a shared library" :
+						"try using shared library path instead");
+			ret = -ENOENT;
+		} else {
+			pr_warn("elf: failed to find symbol '%s' in '%s'\n", name, binary_path);
+		}
+	}
+out:
+	elf_end(elf);
+	close(fd);
+	return ret;
+}
+
+static const char *arch_specific_lib_paths(void)
+{
+	/*
+	 * Based on https://packages.debian.org/sid/libc6.
+	 *
+	 * Assume that the traced program is built for the same architecture
+	 * as libbpf, which should cover the vast majority of cases.
+	 */
+#if defined(__x86_64__)
+	return "/lib/x86_64-linux-gnu";
+#elif defined(__i386__)
+	return "/lib/i386-linux-gnu";
+#elif defined(__s390x__)
+	return "/lib/s390x-linux-gnu";
+#elif defined(__s390__)
+	return "/lib/s390-linux-gnu";
+#elif defined(__arm__) && defined(__SOFTFP__)
+	return "/lib/arm-linux-gnueabi";
+#elif defined(__arm__) && !defined(__SOFTFP__)
+	return "/lib/arm-linux-gnueabihf";
+#elif defined(__aarch64__)
+	return "/lib/aarch64-linux-gnu";
+#elif defined(__mips__) && defined(__MIPSEL__) && _MIPS_SZLONG == 64
+	return "/lib/mips64el-linux-gnuabi64";
+#elif defined(__mips__) && defined(__MIPSEL__) && _MIPS_SZLONG == 32
+	return "/lib/mipsel-linux-gnu";
+#elif defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	return "/lib/powerpc64le-linux-gnu";
+#elif defined(__sparc__) && defined(__arch64__)
+	return "/lib/sparc64-linux-gnu";
+#elif defined(__riscv) && __riscv_xlen == 64
+	return "/lib/riscv64-linux-gnu";
+#else
+	return NULL;
+#endif
+}
+
+/* Get full path to program/shared library. */
+static int resolve_full_path(const char *file, char *result, size_t result_sz)
+{
+	const char *search_paths[3] = {};
+	int i, perm;
+
+	if (str_has_sfx(file, ".so") || strstr(file, ".so.")) {
+		search_paths[0] = getenv("LD_LIBRARY_PATH");
+		search_paths[1] = "/usr/lib64:/usr/lib";
+		search_paths[2] = arch_specific_lib_paths();
+		perm = R_OK;
+	} else {
+		search_paths[0] = getenv("PATH");
+		search_paths[1] = "/usr/bin:/usr/sbin";
+		perm = R_OK | X_OK;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(search_paths); i++) {
+		const char *s;
+
+		if (!search_paths[i])
+			continue;
+		for (s = search_paths[i]; s != NULL; s = strchr(s, ':')) {
+			char *next_path;
+			int seg_len;
+
+			if (s[0] == ':')
+				s++;
+			next_path = strchr(s, ':');
+			seg_len = next_path ? next_path - s : strlen(s);
+			if (!seg_len)
+				continue;
+			snprintf(result, result_sz, "%.*s/%s", seg_len, s, file);
+			/* ensure it has required permissions */
+			if (faccessat(AT_FDCWD, result, perm, AT_EACCESS) < 0)
+				continue;
+			pr_debug("resolved '%s' to '%s'\n", file, result);
+			return 0;
+		}
+	}
+	return -ENOENT;
+}
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
+				const char *binary_path, size_t func_offset,
+				const struct bpf_uprobe_opts *opts)
+{
+	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
+	char errmsg[STRERR_BUFSIZE], *legacy_probe = NULL;
+	char full_binary_path[PATH_MAX];
+	struct bpf_link *link;
+	size_t ref_ctr_off;
+	int pfd, err;
+	bool retprobe, legacy;
+	const char *func_name;
+
+	if (!OPTS_VALID(opts, bpf_uprobe_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	retprobe = OPTS_GET(opts, retprobe, false);
+	ref_ctr_off = OPTS_GET(opts, ref_ctr_offset, 0);
+	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+
+	if (!binary_path)
+		return libbpf_err_ptr(-EINVAL);
+
+	if (!strchr(binary_path, '/')) {
+		err = resolve_full_path(binary_path, full_binary_path,
+					sizeof(full_binary_path));
+		if (err) {
+			pr_warn("prog '%s': failed to resolve full path for '%s': %d\n",
+				prog->name, binary_path, err);
+			return libbpf_err_ptr(err);
+		}
+		binary_path = full_binary_path;
+	}
+	func_name = OPTS_GET(opts, func_name, NULL);
+	if (func_name) {
+		long sym_off;
+
+		sym_off = elf_find_func_offset(binary_path, func_name);
+		if (sym_off < 0)
+			return libbpf_err_ptr(sym_off);
+		func_offset += sym_off;
+	}
+
+	legacy = determine_uprobe_perf_type() < 0;
+	if (!legacy) {
+		pfd = perf_event_open_probe(true /* uprobe */, retprobe, binary_path,
+					    func_offset, pid, ref_ctr_off);
+	} else {
+		char probe_name[PATH_MAX + 64];
+
+		if (ref_ctr_off)
+			return libbpf_err_ptr(-EINVAL);
+
+		gen_uprobe_legacy_event_name(probe_name, sizeof(probe_name),
+					     binary_path, func_offset);
+
+		legacy_probe = strdup(probe_name);
+		if (!legacy_probe)
+			return libbpf_err_ptr(-ENOMEM);
+
+		pfd = perf_event_uprobe_open_legacy(legacy_probe, retprobe,
+						    binary_path, func_offset, pid);
+	}
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("prog '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
+			prog->name, retprobe ? "uretprobe" : "uprobe",
+			binary_path, func_offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_out;
+	}
+
+	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
+	err = libbpf_get_error(link);
+	if (err) {
+		close(pfd);
+		pr_warn("prog '%s': failed to attach to %s '%s:0x%zx': %s\n",
+			prog->name, retprobe ? "uretprobe" : "uprobe",
+			binary_path, func_offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_clean_legacy;
+	}
+	if (legacy) {
+		struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
+
+		perf_link->legacy_probe_name = legacy_probe;
+		perf_link->legacy_is_kprobe = false;
+		perf_link->legacy_is_retprobe = retprobe;
+	}
+	return link;
+
+err_clean_legacy:
+	if (legacy)
+		remove_uprobe_event_legacy(legacy_probe, retprobe);
+err_out:
+	free(legacy_probe);
+	return libbpf_err_ptr(err);
+}
+
+/* Format of u[ret]probe section definition supporting auto-attach:
+ * u[ret]probe/binary:function[+offset]
+ *
+ * binary can be an absolute/relative path or a filename; the latter is resolved to a
+ * full binary path via bpf_program__attach_uprobe_opts.
+ *
+ * Specifying uprobe+ ensures we carry out strict matching; either "uprobe" must be
+ * specified (and auto-attach is not possible) or the above format is specified for
+ * auto-attach.
+ */
+static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts);
+	char *probe_type = NULL, *binary_path = NULL, *func_name = NULL;
+	int n, ret = -EINVAL;
+	long offset = 0;
+
+	*link = NULL;
+
+	n = sscanf(prog->sec_name, "%m[^/]/%m[^:]:%m[a-zA-Z0-9_.]+%li",
+		   &probe_type, &binary_path, &func_name, &offset);
+	switch (n) {
+	case 1:
+		/* handle SEC("u[ret]probe") - format is valid, but auto-attach is impossible. */
+		ret = 0;
+		break;
+	case 2:
+		pr_warn("prog '%s': section '%s' missing ':function[+offset]' specification\n",
+			prog->name, prog->sec_name);
+		break;
+	case 3:
+	case 4:
+		opts.retprobe = strcmp(probe_type, "uretprobe") == 0 ||
+				strcmp(probe_type, "uretprobe.s") == 0;
+		if (opts.retprobe && offset != 0) {
+			pr_warn("prog '%s': uretprobes do not support offset specification\n",
+				prog->name);
+			break;
+		}
+		opts.func_name = func_name;
+		*link = bpf_program__attach_uprobe_opts(prog, -1, binary_path, offset, &opts);
+		ret = libbpf_get_error(*link);
+		break;
+	default:
+		pr_warn("prog '%s': invalid format of section definition '%s'\n", prog->name,
+			prog->sec_name);
+		break;
+	}
+	free(probe_type);
+	free(binary_path);
+	free(func_name);
+
+	return ret;
+}
+
+struct bpf_link *bpf_program__attach_uprobe(const struct bpf_program *prog,
+					    bool retprobe, pid_t pid,
+					    const char *binary_path,
+					    size_t func_offset)
+{
+	DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts, .retprobe = retprobe);
+
+	return bpf_program__attach_uprobe_opts(prog, pid, binary_path, func_offset, &opts);
+}
+
+struct bpf_link *bpf_program__attach_usdt(const struct bpf_program *prog,
+					  pid_t pid, const char *binary_path,
+					  const char *usdt_provider, const char *usdt_name,
+					  const struct bpf_usdt_opts *opts)
+{
+	char resolved_path[512];
+	struct bpf_object *obj = prog->obj;
+	struct bpf_link *link;
+	__u64 usdt_cookie;
+	int err;
+
+	if (!OPTS_VALID(opts, bpf_uprobe_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	if (bpf_program__fd(prog) < 0) {
+		pr_warn("prog '%s': can't attach BPF program w/o FD (did you load it?)\n",
+			prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	if (!binary_path)
+		return libbpf_err_ptr(-EINVAL);
+
+	if (!strchr(binary_path, '/')) {
+		err = resolve_full_path(binary_path, resolved_path, sizeof(resolved_path));
+		if (err) {
+			pr_warn("prog '%s': failed to resolve full path for '%s': %d\n",
+				prog->name, binary_path, err);
+			return libbpf_err_ptr(err);
+		}
+		binary_path = resolved_path;
+	}
+
+	/* USDT manager is instantiated lazily on first USDT attach. It will
+	 * be destroyed together with BPF object in bpf_object__close().
+	 */
+	if (IS_ERR(obj->usdt_man))
+		return libbpf_ptr(obj->usdt_man);
+	if (!obj->usdt_man) {
+		obj->usdt_man = usdt_manager_new(obj);
+		if (IS_ERR(obj->usdt_man))
+			return libbpf_ptr(obj->usdt_man);
+	}
+
+	usdt_cookie = OPTS_GET(opts, usdt_cookie, 0);
+	link = usdt_manager_attach_usdt(obj->usdt_man, prog, pid, binary_path,
+				        usdt_provider, usdt_name, usdt_cookie);
+	err = libbpf_get_error(link);
+	if (err)
+		return libbpf_err_ptr(err);
+	return link;
+}
+
+static int attach_usdt(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	char *path = NULL, *provider = NULL, *name = NULL;
+	const char *sec_name;
+	int n, err;
+
+	sec_name = bpf_program__section_name(prog);
+	if (strcmp(sec_name, "usdt") == 0) {
+		/* no auto-attach for just SEC("usdt") */
+		*link = NULL;
+		return 0;
+	}
+
+	n = sscanf(sec_name, "usdt/%m[^:]:%m[^:]:%m[^:]", &path, &provider, &name);
+	if (n != 3) {
+		pr_warn("invalid section '%s', expected SEC(\"usdt/<path>:<provider>:<name>\")\n",
+			sec_name);
+		err = -EINVAL;
+	} else {
+		*link = bpf_program__attach_usdt(prog, -1 /* any process */, path,
+						 provider, name, NULL);
+		err = libbpf_get_error(*link);
+	}
+	free(path);
+	free(provider);
+	free(name);
+	return err;
+}
+
+static int determine_tracepoint_id(const char *tp_category,
+				   const char *tp_name)
+{
+	char file[PATH_MAX];
+	int ret;
+
+	ret = snprintf(file, sizeof(file), "%s/events/%s/%s/id",
+		       tracefs_path(), tp_category, tp_name);
+	if (ret < 0)
+		return -errno;
+	if (ret >= sizeof(file)) {
+		pr_debug("tracepoint %s/%s path is too long\n",
+			 tp_category, tp_name);
+		return -E2BIG;
+	}
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int perf_event_open_tracepoint(const char *tp_category,
+				      const char *tp_name)
+{
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_event_attr attr;
+	char errmsg[STRERR_BUFSIZE];
+	int tp_id, pfd, err;
+
+	tp_id = determine_tracepoint_id(tp_category, tp_name);
+	if (tp_id < 0) {
+		pr_warn("failed to determine tracepoint '%s/%s' perf event ID: %s\n",
+			tp_category, tp_name,
+			libbpf_strerror_r(tp_id, errmsg, sizeof(errmsg)));
+		return tp_id;
+	}
+
+	memset(&attr, 0, attr_sz);
+	attr.type = PERF_TYPE_TRACEPOINT;
+	attr.size = attr_sz;
+	attr.config = tp_id;
+
+	pfd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, 0 /* cpu */,
+		      -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("tracepoint '%s/%s' perf_event_open() failed: %s\n",
+			tp_category, tp_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return err;
+	}
+	return pfd;
+}
+
+struct bpf_link *bpf_program__attach_tracepoint_opts(const struct bpf_program *prog,
+						     const char *tp_category,
+						     const char *tp_name,
+						     const struct bpf_tracepoint_opts *opts)
+{
+	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int pfd, err;
+
+	if (!OPTS_VALID(opts, bpf_tracepoint_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+
+	pfd = perf_event_open_tracepoint(tp_category, tp_name);
+	if (pfd < 0) {
+		pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
+			prog->name, tp_category, tp_name,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(pfd);
+	}
+	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
+	err = libbpf_get_error(link);
+	if (err) {
+		close(pfd);
+		pr_warn("prog '%s': failed to attach to tracepoint '%s/%s': %s\n",
+			prog->name, tp_category, tp_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(err);
+	}
+	return link;
+}
+
+struct bpf_link *bpf_program__attach_tracepoint(const struct bpf_program *prog,
+						const char *tp_category,
+						const char *tp_name)
+{
+	return bpf_program__attach_tracepoint_opts(prog, tp_category, tp_name, NULL);
+}
+
+static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	char *sec_name, *tp_cat, *tp_name;
+
+	*link = NULL;
+
+	/* no auto-attach for SEC("tp") or SEC("tracepoint") */
+	if (strcmp(prog->sec_name, "tp") == 0 || strcmp(prog->sec_name, "tracepoint") == 0)
+		return 0;
+
+	sec_name = strdup(prog->sec_name);
+	if (!sec_name)
+		return -ENOMEM;
+
+	/* extract "tp/<category>/<name>" or "tracepoint/<category>/<name>" */
+	if (str_has_pfx(prog->sec_name, "tp/"))
+		tp_cat = sec_name + sizeof("tp/") - 1;
+	else
+		tp_cat = sec_name + sizeof("tracepoint/") - 1;
+	tp_name = strchr(tp_cat, '/');
+	if (!tp_name) {
+		free(sec_name);
+		return -EINVAL;
+	}
+	*tp_name = '\0';
+	tp_name++;
+
+	*link = bpf_program__attach_tracepoint(prog, tp_cat, tp_name);
+	free(sec_name);
+	return libbpf_get_error(*link);
+}
+
+struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,
+						    const char *tp_name)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int prog_fd, pfd;
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->detach = &bpf_link__detach_fd;
+
+	pfd = bpf_raw_tracepoint_open(tp_name, prog_fd);
+	if (pfd < 0) {
+		pfd = -errno;
+		free(link);
+		pr_warn("prog '%s': failed to attach to raw tracepoint '%s': %s\n",
+			prog->name, tp_name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(pfd);
+	}
+	link->fd = pfd;
+	return link;
+}
+
+static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	static const char *const prefixes[] = {
+		"raw_tp",
+		"raw_tracepoint",
+		"raw_tp.w",
+		"raw_tracepoint.w",
+	};
+	size_t i;
+	const char *tp_name = NULL;
+
+	*link = NULL;
+
+	for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
+		size_t pfx_len;
+
+		if (!str_has_pfx(prog->sec_name, prefixes[i]))
+			continue;
+
+		pfx_len = strlen(prefixes[i]);
+		/* no auto-attach case of, e.g., SEC("raw_tp") */
+		if (prog->sec_name[pfx_len] == '\0')
+			return 0;
+
+		if (prog->sec_name[pfx_len] != '/')
+			continue;
+
+		tp_name = prog->sec_name + pfx_len + 1;
+		break;
+	}
+
+	if (!tp_name) {
+		pr_warn("prog '%s': invalid section name '%s'\n",
+			prog->name, prog->sec_name);
+		return -EINVAL;
+	}
+
+	*link = bpf_program__attach_raw_tracepoint(prog, tp_name);
+	return libbpf_get_error(*link);
+}
+
+/* Common logic for all BPF program types that attach to a btf_id */
+static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *prog,
+						   const struct bpf_trace_opts *opts)
+{
+	LIBBPF_OPTS(bpf_link_create_opts, link_opts);
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int prog_fd, pfd;
+
+	if (!OPTS_VALID(opts, bpf_trace_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->detach = &bpf_link__detach_fd;
+
+	/* libbpf is smart enough to redirect to BPF_RAW_TRACEPOINT_OPEN on old kernels */
+	link_opts.tracing.cookie = OPTS_GET(opts, cookie, 0);
+	pfd = bpf_link_create(prog_fd, 0, bpf_program__expected_attach_type(prog), &link_opts);
+	if (pfd < 0) {
+		pfd = -errno;
+		free(link);
+		pr_warn("prog '%s': failed to attach: %s\n",
+			prog->name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(pfd);
+	}
+	link->fd = pfd;
+	return link;
+}
+
+struct bpf_link *bpf_program__attach_trace(const struct bpf_program *prog)
+{
+	return bpf_program__attach_btf_id(prog, NULL);
+}
+
+struct bpf_link *bpf_program__attach_trace_opts(const struct bpf_program *prog,
+						const struct bpf_trace_opts *opts)
+{
+	return bpf_program__attach_btf_id(prog, opts);
+}
+
+struct bpf_link *bpf_program__attach_lsm(const struct bpf_program *prog)
+{
+	return bpf_program__attach_btf_id(prog, NULL);
+}
+
+static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	*link = bpf_program__attach_trace(prog);
+	return libbpf_get_error(*link);
+}
+
+static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	*link = bpf_program__attach_lsm(prog);
+	return libbpf_get_error(*link);
+}
+
+static struct bpf_link *
+bpf_program__attach_fd(const struct bpf_program *prog, int target_fd, int btf_id,
+		       const char *target_name)
+{
+	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts,
+			    .target_btf_id = btf_id);
+	enum bpf_attach_type attach_type;
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int prog_fd, link_fd;
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->detach = &bpf_link__detach_fd;
+
+	attach_type = bpf_program__expected_attach_type(prog);
+	link_fd = bpf_link_create(prog_fd, target_fd, attach_type, &opts);
+	if (link_fd < 0) {
+		link_fd = -errno;
+		free(link);
+		pr_warn("prog '%s': failed to attach to %s: %s\n",
+			prog->name, target_name,
+			libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(link_fd);
+	}
+	link->fd = link_fd;
+	return link;
+}
+
+struct bpf_link *
+bpf_program__attach_cgroup(const struct bpf_program *prog, int cgroup_fd)
+{
+	return bpf_program__attach_fd(prog, cgroup_fd, 0, "cgroup");
+}
+
+struct bpf_link *
+bpf_program__attach_netns(const struct bpf_program *prog, int netns_fd)
+{
+	return bpf_program__attach_fd(prog, netns_fd, 0, "netns");
+}
+
+struct bpf_link *bpf_program__attach_xdp(const struct bpf_program *prog, int ifindex)
+{
+	/* target_fd/target_ifindex use the same field in LINK_CREATE */
+	return bpf_program__attach_fd(prog, ifindex, 0, "xdp");
+}
+
+struct bpf_link *bpf_program__attach_freplace(const struct bpf_program *prog,
+					      int target_fd,
+					      const char *attach_func_name)
+{
+	int btf_id;
+
+	if (!!target_fd != !!attach_func_name) {
+		pr_warn("prog '%s': supply none or both of target_fd and attach_func_name\n",
+			prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	if (prog->type != BPF_PROG_TYPE_EXT) {
+		pr_warn("prog '%s': only BPF_PROG_TYPE_EXT can attach as freplace",
+			prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	if (target_fd) {
+		btf_id = libbpf_find_prog_btf_id(attach_func_name, target_fd);
+		if (btf_id < 0)
+			return libbpf_err_ptr(btf_id);
+
+		return bpf_program__attach_fd(prog, target_fd, btf_id, "freplace");
+	} else {
+		/* no target, so use raw_tracepoint_open for compatibility
+		 * with old kernels
+		 */
+		return bpf_program__attach_trace(prog);
+	}
+}
+
+struct bpf_link *
+bpf_program__attach_iter(const struct bpf_program *prog,
+			 const struct bpf_iter_attach_opts *opts)
+{
+	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int prog_fd, link_fd;
+	__u32 target_fd = 0;
+
+	if (!OPTS_VALID(opts, bpf_iter_attach_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	link_create_opts.iter_info = OPTS_GET(opts, link_info, (void *)0);
+	link_create_opts.iter_info_len = OPTS_GET(opts, link_info_len, 0);
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+		return libbpf_err_ptr(-EINVAL);
+	}
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-ENOMEM);
+	link->detach = &bpf_link__detach_fd;
+
+	link_fd = bpf_link_create(prog_fd, target_fd, BPF_TRACE_ITER,
+				  &link_create_opts);
+	if (link_fd < 0) {
+		link_fd = -errno;
+		free(link);
+		pr_warn("prog '%s': failed to attach to iterator: %s\n",
+			prog->name, libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
+		return libbpf_err_ptr(link_fd);
+	}
+	link->fd = link_fd;
+	return link;
+}
+
+static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	*link = bpf_program__attach_iter(prog, NULL);
+	return libbpf_get_error(*link);
+}
+
+struct bpf_link *bpf_program__attach(const struct bpf_program *prog)
+{
+	struct bpf_link *link = NULL;
+	int err;
+
+	if (!prog->sec_def || !prog->sec_def->prog_attach_fn)
+		return libbpf_err_ptr(-EOPNOTSUPP);
+
+	err = prog->sec_def->prog_attach_fn(prog, prog->sec_def->cookie, &link);
+	if (err)
+		return libbpf_err_ptr(err);
+
+	/* When calling bpf_program__attach() explicitly, auto-attach support
+	 * is expected to work, so NULL returned link is considered an error.
+	 * This is different for skeleton's attach, see comment in
+	 * bpf_object__attach_skeleton().
+	 */
+	if (!link)
+		return libbpf_err_ptr(-EOPNOTSUPP);
+
+	return link;
+}
+
+static int bpf_link__detach_struct_ops(struct bpf_link *link)
+{
+	__u32 zero = 0;
+
+	if (bpf_map_delete_elem(link->fd, &zero))
+		return -errno;
+
+	return 0;
+}
+
+struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map)
+{
+	struct bpf_struct_ops *st_ops;
+	struct bpf_link *link;
+	__u32 i, zero = 0;
+	int err;
+
+	if (!bpf_map__is_struct_ops(map) || map->fd == -1)
+		return libbpf_err_ptr(-EINVAL);
+
+	link = calloc(1, sizeof(*link));
+	if (!link)
+		return libbpf_err_ptr(-EINVAL);
+
+	st_ops = map->st_ops;
+	for (i = 0; i < btf_vlen(st_ops->type); i++) {
+		struct bpf_program *prog = st_ops->progs[i];
+		void *kern_data;
+		int prog_fd;
+
+		if (!prog)
+			continue;
+
+		prog_fd = bpf_program__fd(prog);
+		kern_data = st_ops->kern_vdata + st_ops->kern_func_off[i];
+		*(unsigned long *)kern_data = prog_fd;
+	}
+
+	err = bpf_map_update_elem(map->fd, &zero, st_ops->kern_vdata, 0);
+	if (err) {
+		err = -errno;
+		free(link);
+		return libbpf_err_ptr(err);
+	}
+
+	link->detach = bpf_link__detach_struct_ops;
+	link->fd = map->fd;
+
+	return link;
+}
+
+typedef enum bpf_perf_event_ret (*bpf_perf_event_print_t)(struct perf_event_header *hdr,
+							  void *private_data);
+
+static enum bpf_perf_event_ret
+perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
+		       void **copy_mem, size_t *copy_size,
+		       bpf_perf_event_print_t fn, void *private_data)
+{
+	struct perf_event_mmap_page *header = mmap_mem;
+	__u64 data_head = ring_buffer_read_head(header);
+	__u64 data_tail = header->data_tail;
+	void *base = ((__u8 *)header) + page_size;
+	int ret = LIBBPF_PERF_EVENT_CONT;
+	struct perf_event_header *ehdr;
+	size_t ehdr_size;
+
+	while (data_head != data_tail) {
+		ehdr = base + (data_tail & (mmap_size - 1));
+		ehdr_size = ehdr->size;
+
+		if (((void *)ehdr) + ehdr_size > base + mmap_size) {
+			void *copy_start = ehdr;
+			size_t len_first = base + mmap_size - copy_start;
+			size_t len_secnd = ehdr_size - len_first;
+
+			if (*copy_size < ehdr_size) {
+				free(*copy_mem);
+				*copy_mem = malloc(ehdr_size);
+				if (!*copy_mem) {
+					*copy_size = 0;
+					ret = LIBBPF_PERF_EVENT_ERROR;
+					break;
+				}
+				*copy_size = ehdr_size;
+			}
+
+			memcpy(*copy_mem, copy_start, len_first);
+			memcpy(*copy_mem + len_first, base, len_secnd);
+			ehdr = *copy_mem;
+		}
+
+		ret = fn(ehdr, private_data);
+		data_tail += ehdr_size;
+		if (ret != LIBBPF_PERF_EVENT_CONT)
+			break;
+	}
+
+	ring_buffer_write_tail(header, data_tail);
+	return libbpf_err(ret);
+}
+
+struct perf_buffer;
+
+struct perf_buffer_params {
+	struct perf_event_attr *attr;
+	/* if event_cb is specified, it takes precendence */
+	perf_buffer_event_fn event_cb;
+	/* sample_cb and lost_cb are higher-level common-case callbacks */
+	perf_buffer_sample_fn sample_cb;
+	perf_buffer_lost_fn lost_cb;
+	void *ctx;
+	int cpu_cnt;
+	int *cpus;
+	int *map_keys;
+};
+
+struct perf_cpu_buf {
+	struct perf_buffer *pb;
+	void *base; /* mmap()'ed memory */
+	void *buf; /* for reconstructing segmented data */
+	size_t buf_size;
+	int fd;
+	int cpu;
+	int map_key;
+};
+
+struct perf_buffer {
+	perf_buffer_event_fn event_cb;
+	perf_buffer_sample_fn sample_cb;
+	perf_buffer_lost_fn lost_cb;
+	void *ctx; /* passed into callbacks */
+
+	size_t page_size;
+	size_t mmap_size;
+	struct perf_cpu_buf **cpu_bufs;
+	struct epoll_event *events;
+	int cpu_cnt; /* number of allocated CPU buffers */
+	int epoll_fd; /* perf event FD */
+	int map_fd; /* BPF_MAP_TYPE_PERF_EVENT_ARRAY BPF map FD */
+};
+
+static void perf_buffer__free_cpu_buf(struct perf_buffer *pb,
+				      struct perf_cpu_buf *cpu_buf)
+{
+	if (!cpu_buf)
+		return;
+	if (cpu_buf->base &&
+	    munmap(cpu_buf->base, pb->mmap_size + pb->page_size))
+		pr_warn("failed to munmap cpu_buf #%d\n", cpu_buf->cpu);
+	if (cpu_buf->fd >= 0) {
+		ioctl(cpu_buf->fd, PERF_EVENT_IOC_DISABLE, 0);
+		close(cpu_buf->fd);
+	}
+	free(cpu_buf->buf);
+	free(cpu_buf);
+}
+
+void perf_buffer__free(struct perf_buffer *pb)
+{
+	int i;
+
+	if (IS_ERR_OR_NULL(pb))
+		return;
+	if (pb->cpu_bufs) {
+		for (i = 0; i < pb->cpu_cnt; i++) {
+			struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
+
+			if (!cpu_buf)
+				continue;
+
+			bpf_map_delete_elem(pb->map_fd, &cpu_buf->map_key);
+			perf_buffer__free_cpu_buf(pb, cpu_buf);
+		}
+		free(pb->cpu_bufs);
+	}
+	if (pb->epoll_fd >= 0)
+		close(pb->epoll_fd);
+	free(pb->events);
+	free(pb);
+}
+
+static struct perf_cpu_buf *
+perf_buffer__open_cpu_buf(struct perf_buffer *pb, struct perf_event_attr *attr,
+			  int cpu, int map_key)
+{
+	struct perf_cpu_buf *cpu_buf;
+	char msg[STRERR_BUFSIZE];
+	int err;
+
+	cpu_buf = calloc(1, sizeof(*cpu_buf));
+	if (!cpu_buf)
+		return ERR_PTR(-ENOMEM);
+
+	cpu_buf->pb = pb;
+	cpu_buf->cpu = cpu;
+	cpu_buf->map_key = map_key;
+
+	cpu_buf->fd = syscall(__NR_perf_event_open, attr, -1 /* pid */, cpu,
+			      -1, PERF_FLAG_FD_CLOEXEC);
+	if (cpu_buf->fd < 0) {
+		err = -errno;
+		pr_warn("failed to open perf buffer event on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	cpu_buf->base = mmap(NULL, pb->mmap_size + pb->page_size,
+			     PROT_READ | PROT_WRITE, MAP_SHARED,
+			     cpu_buf->fd, 0);
+	if (cpu_buf->base == MAP_FAILED) {
+		cpu_buf->base = NULL;
+		err = -errno;
+		pr_warn("failed to mmap perf buffer on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	if (ioctl(cpu_buf->fd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
+		err = -errno;
+		pr_warn("failed to enable perf buffer event on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	return cpu_buf;
+
+error:
+	perf_buffer__free_cpu_buf(pb, cpu_buf);
+	return (struct perf_cpu_buf *)ERR_PTR(err);
+}
+
+static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
+					      struct perf_buffer_params *p);
+
+struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
+				     perf_buffer_sample_fn sample_cb,
+				     perf_buffer_lost_fn lost_cb,
+				     void *ctx,
+				     const struct perf_buffer_opts *opts)
+{
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_buffer_params p = {};
+	struct perf_event_attr attr;
+
+	if (!OPTS_VALID(opts, perf_buffer_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.size = attr_sz;
+	attr.config = PERF_COUNT_SW_BPF_OUTPUT;
+	attr.type = PERF_TYPE_SOFTWARE;
+	attr.sample_type = PERF_SAMPLE_RAW;
+	attr.sample_period = 1;
+	attr.wakeup_events = 1;
+
+	p.attr = &attr;
+	p.sample_cb = sample_cb;
+	p.lost_cb = lost_cb;
+	p.ctx = ctx;
+
+	return libbpf_ptr(__perf_buffer__new(map_fd, page_cnt, &p));
+}
+
+struct perf_buffer *perf_buffer__new_raw(int map_fd, size_t page_cnt,
+					 struct perf_event_attr *attr,
+					 perf_buffer_event_fn event_cb, void *ctx,
+					 const struct perf_buffer_raw_opts *opts)
+{
+	struct perf_buffer_params p = {};
+
+	if (!attr)
+		return libbpf_err_ptr(-EINVAL);
+
+	if (!OPTS_VALID(opts, perf_buffer_raw_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	p.attr = attr;
+	p.event_cb = event_cb;
+	p.ctx = ctx;
+	p.cpu_cnt = OPTS_GET(opts, cpu_cnt, 0);
+	p.cpus = OPTS_GET(opts, cpus, NULL);
+	p.map_keys = OPTS_GET(opts, map_keys, NULL);
+
+	return libbpf_ptr(__perf_buffer__new(map_fd, page_cnt, &p));
+}
+
+static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
+					      struct perf_buffer_params *p)
+{
+	const char *online_cpus_file = "/sys/devices/system/cpu/online";
+	struct bpf_map_info map;
+	char msg[STRERR_BUFSIZE];
+	struct perf_buffer *pb;
+	bool *online = NULL;
+	__u32 map_info_len;
+	int err, i, j, n;
+
+	if (page_cnt == 0 || (page_cnt & (page_cnt - 1))) {
+		pr_warn("page count should be power of two, but is %zu\n",
+			page_cnt);
+		return ERR_PTR(-EINVAL);
+	}
+
+	/* best-effort sanity checks */
+	memset(&map, 0, sizeof(map));
+	map_info_len = sizeof(map);
+	err = bpf_obj_get_info_by_fd(map_fd, &map, &map_info_len);
+	if (err) {
+		err = -errno;
+		/* if BPF_OBJ_GET_INFO_BY_FD is supported, will return
+		 * -EBADFD, -EFAULT, or -E2BIG on real error
+		 */
+		if (err != -EINVAL) {
+			pr_warn("failed to get map info for map FD %d: %s\n",
+				map_fd, libbpf_strerror_r(err, msg, sizeof(msg)));
+			return ERR_PTR(err);
+		}
+		pr_debug("failed to get map info for FD %d; API not supported? Ignoring...\n",
+			 map_fd);
+	} else {
+		if (map.type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) {
+			pr_warn("map '%s' should be BPF_MAP_TYPE_PERF_EVENT_ARRAY\n",
+				map.name);
+			return ERR_PTR(-EINVAL);
+		}
+	}
+
+	pb = calloc(1, sizeof(*pb));
+	if (!pb)
+		return ERR_PTR(-ENOMEM);
+
+	pb->event_cb = p->event_cb;
+	pb->sample_cb = p->sample_cb;
+	pb->lost_cb = p->lost_cb;
+	pb->ctx = p->ctx;
+
+	pb->page_size = getpagesize();
+	pb->mmap_size = pb->page_size * page_cnt;
+	pb->map_fd = map_fd;
+
+	pb->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
+	if (pb->epoll_fd < 0) {
+		err = -errno;
+		pr_warn("failed to create epoll instance: %s\n",
+			libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	if (p->cpu_cnt > 0) {
+		pb->cpu_cnt = p->cpu_cnt;
+	} else {
+		pb->cpu_cnt = libbpf_num_possible_cpus();
+		if (pb->cpu_cnt < 0) {
+			err = pb->cpu_cnt;
+			goto error;
+		}
+		if (map.max_entries && map.max_entries < pb->cpu_cnt)
+			pb->cpu_cnt = map.max_entries;
+	}
+
+	pb->events = calloc(pb->cpu_cnt, sizeof(*pb->events));
+	if (!pb->events) {
+		err = -ENOMEM;
+		pr_warn("failed to allocate events: out of memory\n");
+		goto error;
+	}
+	pb->cpu_bufs = calloc(pb->cpu_cnt, sizeof(*pb->cpu_bufs));
+	if (!pb->cpu_bufs) {
+		err = -ENOMEM;
+		pr_warn("failed to allocate buffers: out of memory\n");
+		goto error;
+	}
+
+	err = parse_cpu_mask_file(online_cpus_file, &online, &n);
+	if (err) {
+		pr_warn("failed to get online CPU mask: %d\n", err);
+		goto error;
+	}
+
+	for (i = 0, j = 0; i < pb->cpu_cnt; i++) {
+		struct perf_cpu_buf *cpu_buf;
+		int cpu, map_key;
+
+		cpu = p->cpu_cnt > 0 ? p->cpus[i] : i;
+		map_key = p->cpu_cnt > 0 ? p->map_keys[i] : i;
+
+		/* in case user didn't explicitly requested particular CPUs to
+		 * be attached to, skip offline/not present CPUs
+		 */
+		if (p->cpu_cnt <= 0 && (cpu >= n || !online[cpu]))
+			continue;
+
+		cpu_buf = perf_buffer__open_cpu_buf(pb, p->attr, cpu, map_key);
+		if (IS_ERR(cpu_buf)) {
+			err = PTR_ERR(cpu_buf);
+			goto error;
+		}
+
+		pb->cpu_bufs[j] = cpu_buf;
+
+		err = bpf_map_update_elem(pb->map_fd, &map_key,
+					  &cpu_buf->fd, 0);
+		if (err) {
+			err = -errno;
+			pr_warn("failed to set cpu #%d, key %d -> perf FD %d: %s\n",
+				cpu, map_key, cpu_buf->fd,
+				libbpf_strerror_r(err, msg, sizeof(msg)));
+			goto error;
+		}
+
+		pb->events[j].events = EPOLLIN;
+		pb->events[j].data.ptr = cpu_buf;
+		if (epoll_ctl(pb->epoll_fd, EPOLL_CTL_ADD, cpu_buf->fd,
+			      &pb->events[j]) < 0) {
+			err = -errno;
+			pr_warn("failed to epoll_ctl cpu #%d perf FD %d: %s\n",
+				cpu, cpu_buf->fd,
+				libbpf_strerror_r(err, msg, sizeof(msg)));
+			goto error;
+		}
+		j++;
+	}
+	pb->cpu_cnt = j;
+	free(online);
+
+	return pb;
+
+error:
+	free(online);
+	if (pb)
+		perf_buffer__free(pb);
+	return ERR_PTR(err);
+}
+
+struct perf_sample_raw {
+	struct perf_event_header header;
+	uint32_t size;
+	char data[];
+};
+
+struct perf_sample_lost {
+	struct perf_event_header header;
+	uint64_t id;
+	uint64_t lost;
+	uint64_t sample_id;
+};
+
+static enum bpf_perf_event_ret
+perf_buffer__process_record(struct perf_event_header *e, void *ctx)
+{
+	struct perf_cpu_buf *cpu_buf = ctx;
+	struct perf_buffer *pb = cpu_buf->pb;
+	void *data = e;
+
+	/* user wants full control over parsing perf event */
+	if (pb->event_cb)
+		return pb->event_cb(pb->ctx, cpu_buf->cpu, e);
+
+	switch (e->type) {
+	case PERF_RECORD_SAMPLE: {
+		struct perf_sample_raw *s = data;
+
+		if (pb->sample_cb)
+			pb->sample_cb(pb->ctx, cpu_buf->cpu, s->data, s->size);
+		break;
+	}
+	case PERF_RECORD_LOST: {
+		struct perf_sample_lost *s = data;
+
+		if (pb->lost_cb)
+			pb->lost_cb(pb->ctx, cpu_buf->cpu, s->lost);
+		break;
+	}
+	default:
+		pr_warn("unknown perf sample type %d\n", e->type);
+		return LIBBPF_PERF_EVENT_ERROR;
+	}
+	return LIBBPF_PERF_EVENT_CONT;
+}
+
+static int perf_buffer__process_records(struct perf_buffer *pb,
+					struct perf_cpu_buf *cpu_buf)
+{
+	enum bpf_perf_event_ret ret;
+
+	ret = perf_event_read_simple(cpu_buf->base, pb->mmap_size,
+				     pb->page_size, &cpu_buf->buf,
+				     &cpu_buf->buf_size,
+				     perf_buffer__process_record, cpu_buf);
+	if (ret != LIBBPF_PERF_EVENT_CONT)
+		return ret;
+	return 0;
+}
+
+int perf_buffer__epoll_fd(const struct perf_buffer *pb)
+{
+	return pb->epoll_fd;
+}
+
+int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms)
+{
+	int i, cnt, err;
+
+	cnt = epoll_wait(pb->epoll_fd, pb->events, pb->cpu_cnt, timeout_ms);
+	if (cnt < 0)
+		return -errno;
+
+	for (i = 0; i < cnt; i++) {
+		struct perf_cpu_buf *cpu_buf = pb->events[i].data.ptr;
+
+		err = perf_buffer__process_records(pb, cpu_buf);
+		if (err) {
+			pr_warn("error while processing records: %d\n", err);
+			return libbpf_err(err);
+		}
+	}
+	return cnt;
+}
+
+/* Return number of PERF_EVENT_ARRAY map slots set up by this perf_buffer
+ * manager.
+ */
+size_t perf_buffer__buffer_cnt(const struct perf_buffer *pb)
+{
+	return pb->cpu_cnt;
+}
+
+/*
+ * Return perf_event FD of a ring buffer in *buf_idx* slot of
+ * PERF_EVENT_ARRAY BPF map. This FD can be polled for new data using
+ * select()/poll()/epoll() Linux syscalls.
+ */
+int perf_buffer__buffer_fd(const struct perf_buffer *pb, size_t buf_idx)
+{
+	struct perf_cpu_buf *cpu_buf;
+
+	if (buf_idx >= pb->cpu_cnt)
+		return libbpf_err(-EINVAL);
+
+	cpu_buf = pb->cpu_bufs[buf_idx];
+	if (!cpu_buf)
+		return libbpf_err(-ENOENT);
+
+	return cpu_buf->fd;
+}
+
+int perf_buffer__buffer(struct perf_buffer *pb, int buf_idx, void **buf, size_t *buf_size)
+{
+	struct perf_cpu_buf *cpu_buf;
+
+	if (buf_idx >= pb->cpu_cnt)
+		return libbpf_err(-EINVAL);
+
+	cpu_buf = pb->cpu_bufs[buf_idx];
+	if (!cpu_buf)
+		return libbpf_err(-ENOENT);
+
+	*buf = cpu_buf->base;
+	*buf_size = pb->mmap_size;
+	return 0;
+}
+
+/*
+ * Consume data from perf ring buffer corresponding to slot *buf_idx* in
+ * PERF_EVENT_ARRAY BPF map without waiting/polling. If there is no data to
+ * consume, do nothing and return success.
+ * Returns:
+ *   - 0 on success;
+ *   - <0 on failure.
+ */
+int perf_buffer__consume_buffer(struct perf_buffer *pb, size_t buf_idx)
+{
+	struct perf_cpu_buf *cpu_buf;
+
+	if (buf_idx >= pb->cpu_cnt)
+		return libbpf_err(-EINVAL);
+
+	cpu_buf = pb->cpu_bufs[buf_idx];
+	if (!cpu_buf)
+		return libbpf_err(-ENOENT);
+
+	return perf_buffer__process_records(pb, cpu_buf);
+}
+
+int perf_buffer__consume(struct perf_buffer *pb)
+{
+	int i, err;
+
+	for (i = 0; i < pb->cpu_cnt; i++) {
+		struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
+
+		if (!cpu_buf)
+			continue;
+
+		err = perf_buffer__process_records(pb, cpu_buf);
+		if (err) {
+			pr_warn("perf_buffer: failed to process records in buffer #%d: %d\n", i, err);
+			return libbpf_err(err);
+		}
+	}
+	return 0;
+}
+
+int bpf_program__set_attach_target(struct bpf_program *prog,
+				   int attach_prog_fd,
+				   const char *attach_func_name)
+{
+	int btf_obj_fd = 0, btf_id = 0, err;
+
+	if (!prog || attach_prog_fd < 0)
+		return libbpf_err(-EINVAL);
+
+	if (prog->obj->loaded)
+		return libbpf_err(-EINVAL);
+
+	if (attach_prog_fd && !attach_func_name) {
+		/* remember attach_prog_fd and let bpf_program__load() find
+		 * BTF ID during the program load
+		 */
+		prog->attach_prog_fd = attach_prog_fd;
+		return 0;
+	}
+
+	if (attach_prog_fd) {
+		btf_id = libbpf_find_prog_btf_id(attach_func_name,
+						 attach_prog_fd);
+		if (btf_id < 0)
+			return libbpf_err(btf_id);
+	} else {
+		if (!attach_func_name)
+			return libbpf_err(-EINVAL);
+
+		/* load btf_vmlinux, if not yet */
+		err = bpf_object__load_vmlinux_btf(prog->obj, true);
+		if (err)
+			return libbpf_err(err);
+		err = find_kernel_btf_id(prog->obj, attach_func_name,
+					 prog->expected_attach_type,
+					 &btf_obj_fd, &btf_id);
+		if (err)
+			return libbpf_err(err);
+	}
+
+	prog->attach_btf_id = btf_id;
+	prog->attach_btf_obj_fd = btf_obj_fd;
+	prog->attach_prog_fd = attach_prog_fd;
+	return 0;
+}
+
+int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz)
+{
+	int err = 0, n, len, start, end = -1;
+	bool *tmp;
+
+	*mask = NULL;
+	*mask_sz = 0;
+
+	/* Each sub string separated by ',' has format \d+-\d+ or \d+ */
+	while (*s) {
+		if (*s == ',' || *s == '\n') {
+			s++;
+			continue;
+		}
+		n = sscanf(s, "%d%n-%d%n", &start, &len, &end, &len);
+		if (n <= 0 || n > 2) {
+			pr_warn("Failed to get CPU range %s: %d\n", s, n);
+			err = -EINVAL;
+			goto cleanup;
+		} else if (n == 1) {
+			end = start;
+		}
+		if (start < 0 || start > end) {
+			pr_warn("Invalid CPU range [%d,%d] in %s\n",
+				start, end, s);
+			err = -EINVAL;
+			goto cleanup;
+		}
+		tmp = realloc(*mask, end + 1);
+		if (!tmp) {
+			err = -ENOMEM;
+			goto cleanup;
+		}
+		*mask = tmp;
+		memset(tmp + *mask_sz, 0, start - *mask_sz);
+		memset(tmp + start, 1, end - start + 1);
+		*mask_sz = end + 1;
+		s += len;
+	}
+	if (!*mask_sz) {
+		pr_warn("Empty CPU range\n");
+		return -EINVAL;
+	}
+	return 0;
+cleanup:
+	free(*mask);
+	*mask = NULL;
+	return err;
+}
+
+int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz)
+{
+	int fd, err = 0, len;
+	char buf[128];
+
+	fd = open(fcpu, O_RDONLY | O_CLOEXEC);
+	if (fd < 0) {
+		err = -errno;
+		pr_warn("Failed to open cpu mask file %s: %d\n", fcpu, err);
+		return err;
+	}
+	len = read(fd, buf, sizeof(buf));
+	close(fd);
+	if (len <= 0) {
+		err = len ? -errno : -EINVAL;
+		pr_warn("Failed to read cpu mask from %s: %d\n", fcpu, err);
+		return err;
+	}
+	if (len >= sizeof(buf)) {
+		pr_warn("CPU mask is too big in file %s\n", fcpu);
+		return -E2BIG;
+	}
+	buf[len] = '\0';
+
+	return parse_cpu_mask_str(buf, mask, mask_sz);
+}
+
+int libbpf_num_possible_cpus(void)
+{
+	static const char *fcpu = "/sys/devices/system/cpu/possible";
+	static int cpus;
+	int err, n, i, tmp_cpus;
+	bool *mask;
+
+	tmp_cpus = READ_ONCE(cpus);
+	if (tmp_cpus > 0)
+		return tmp_cpus;
+
+	err = parse_cpu_mask_file(fcpu, &mask, &n);
+	if (err)
+		return libbpf_err(err);
+
+	tmp_cpus = 0;
+	for (i = 0; i < n; i++) {
+		if (mask[i])
+			tmp_cpus++;
+	}
+	free(mask);
+
+	WRITE_ONCE(cpus, tmp_cpus);
+	return tmp_cpus;
+}
+
+static int populate_skeleton_maps(const struct bpf_object *obj,
+				  struct bpf_map_skeleton *maps,
+				  size_t map_cnt)
+{
+	int i;
+
+	for (i = 0; i < map_cnt; i++) {
+		struct bpf_map **map = maps[i].map;
+		const char *name = maps[i].name;
+		void **mmaped = maps[i].mmaped;
+
+		*map = bpf_object__find_map_by_name(obj, name);
+		if (!*map) {
+			pr_warn("failed to find skeleton map '%s'\n", name);
+			return -ESRCH;
+		}
+
+		/* externs shouldn't be pre-setup from user code */
+		if (mmaped && (*map)->libbpf_type != LIBBPF_MAP_KCONFIG)
+			*mmaped = (*map)->mmaped;
+	}
+	return 0;
+}
+
+static int populate_skeleton_progs(const struct bpf_object *obj,
+				   struct bpf_prog_skeleton *progs,
+				   size_t prog_cnt)
+{
+	int i;
+
+	for (i = 0; i < prog_cnt; i++) {
+		struct bpf_program **prog = progs[i].prog;
+		const char *name = progs[i].name;
+
+		*prog = bpf_object__find_program_by_name(obj, name);
+		if (!*prog) {
+			pr_warn("failed to find skeleton program '%s'\n", name);
+			return -ESRCH;
+		}
+	}
+	return 0;
+}
+
+int bpf_object__open_skeleton(struct bpf_object_skeleton *s,
+			      const struct bpf_object_open_opts *opts)
+{
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, skel_opts,
+		.object_name = s->name,
+	);
+	struct bpf_object *obj;
+	int err;
+
+	/* Attempt to preserve opts->object_name, unless overriden by user
+	 * explicitly. Overwriting object name for skeletons is discouraged,
+	 * as it breaks global data maps, because they contain object name
+	 * prefix as their own map name prefix. When skeleton is generated,
+	 * bpftool is making an assumption that this name will stay the same.
+	 */
+	if (opts) {
+		memcpy(&skel_opts, opts, sizeof(*opts));
+		if (!opts->object_name)
+			skel_opts.object_name = s->name;
+	}
+
+	obj = bpf_object__open_mem(s->data, s->data_sz, &skel_opts);
+	err = libbpf_get_error(obj);
+	if (err) {
+		pr_warn("failed to initialize skeleton BPF object '%s': %d\n",
+			s->name, err);
+		return libbpf_err(err);
+	}
+
+	*s->obj = obj;
+	err = populate_skeleton_maps(obj, s->maps, s->map_cnt);
+	if (err) {
+		pr_warn("failed to populate skeleton maps for '%s': %d\n", s->name, err);
+		return libbpf_err(err);
+	}
+
+	err = populate_skeleton_progs(obj, s->progs, s->prog_cnt);
+	if (err) {
+		pr_warn("failed to populate skeleton progs for '%s': %d\n", s->name, err);
+		return libbpf_err(err);
+	}
+
+	return 0;
+}
+
+int bpf_object__open_subskeleton(struct bpf_object_subskeleton *s)
+{
+	int err, len, var_idx, i;
+	const char *var_name;
+	const struct bpf_map *map;
+	struct btf *btf;
+	__u32 map_type_id;
+	const struct btf_type *map_type, *var_type;
+	const struct bpf_var_skeleton *var_skel;
+	struct btf_var_secinfo *var;
+
+	if (!s->obj)
+		return libbpf_err(-EINVAL);
+
+	btf = bpf_object__btf(s->obj);
+	if (!btf) {
+		pr_warn("subskeletons require BTF at runtime (object %s)\n",
+		        bpf_object__name(s->obj));
+		return libbpf_err(-errno);
+	}
+
+	err = populate_skeleton_maps(s->obj, s->maps, s->map_cnt);
+	if (err) {
+		pr_warn("failed to populate subskeleton maps: %d\n", err);
+		return libbpf_err(err);
+	}
+
+	err = populate_skeleton_progs(s->obj, s->progs, s->prog_cnt);
+	if (err) {
+		pr_warn("failed to populate subskeleton maps: %d\n", err);
+		return libbpf_err(err);
+	}
+
+	for (var_idx = 0; var_idx < s->var_cnt; var_idx++) {
+		var_skel = &s->vars[var_idx];
+		map = *var_skel->map;
+		map_type_id = bpf_map__btf_value_type_id(map);
+		map_type = btf__type_by_id(btf, map_type_id);
+
+		if (!btf_is_datasec(map_type)) {
+			pr_warn("type for map '%1$s' is not a datasec: %2$s",
+				bpf_map__name(map),
+				__btf_kind_str(btf_kind(map_type)));
+			return libbpf_err(-EINVAL);
+		}
+
+		len = btf_vlen(map_type);
+		var = btf_var_secinfos(map_type);
+		for (i = 0; i < len; i++, var++) {
+			var_type = btf__type_by_id(btf, var->type);
+			var_name = btf__name_by_offset(btf, var_type->name_off);
+			if (strcmp(var_name, var_skel->name) == 0) {
+				*var_skel->addr = map->mmaped + var->offset;
+				break;
+			}
+		}
+	}
+	return 0;
+}
+
+void bpf_object__destroy_subskeleton(struct bpf_object_subskeleton *s)
+{
+	if (!s)
+		return;
+	free(s->maps);
+	free(s->progs);
+	free(s->vars);
+	free(s);
+}
+
+int bpf_object__load_skeleton(struct bpf_object_skeleton *s)
+{
+	int i, err;
+
+	err = bpf_object__load(*s->obj);
+	if (err) {
+		pr_warn("failed to load BPF skeleton '%s': %d\n", s->name, err);
+		return libbpf_err(err);
+	}
+
+	for (i = 0; i < s->map_cnt; i++) {
+		struct bpf_map *map = *s->maps[i].map;
+		size_t mmap_sz = bpf_map_mmap_sz(map);
+		int prot, map_fd = bpf_map__fd(map);
+		void **mmaped = s->maps[i].mmaped;
+
+		if (!mmaped)
+			continue;
+
+		if (!(map->def.map_flags & BPF_F_MMAPABLE)) {
+			*mmaped = NULL;
+			continue;
+		}
+
+		if (map->def.map_flags & BPF_F_RDONLY_PROG)
+			prot = PROT_READ;
+		else
+			prot = PROT_READ | PROT_WRITE;
+
+		/* Remap anonymous mmap()-ed "map initialization image" as
+		 * a BPF map-backed mmap()-ed memory, but preserving the same
+		 * memory address. This will cause kernel to change process'
+		 * page table to point to a different piece of kernel memory,
+		 * but from userspace point of view memory address (and its
+		 * contents, being identical at this point) will stay the
+		 * same. This mapping will be released by bpf_object__close()
+		 * as per normal clean up procedure, so we don't need to worry
+		 * about it from skeleton's clean up perspective.
+		 */
+		*mmaped = mmap(map->mmaped, mmap_sz, prot,
+				MAP_SHARED | MAP_FIXED, map_fd, 0);
+		if (*mmaped == MAP_FAILED) {
+			err = -errno;
+			*mmaped = NULL;
+			pr_warn("failed to re-mmap() map '%s': %d\n",
+				 bpf_map__name(map), err);
+			return libbpf_err(err);
+		}
+	}
+
+	return 0;
+}
+
+int bpf_object__attach_skeleton(struct bpf_object_skeleton *s)
+{
+	int i, err;
+
+	for (i = 0; i < s->prog_cnt; i++) {
+		struct bpf_program *prog = *s->progs[i].prog;
+		struct bpf_link **link = s->progs[i].link;
+
+		if (!prog->autoload || !prog->autoattach)
+			continue;
+
+		/* auto-attaching not supported for this program */
+		if (!prog->sec_def || !prog->sec_def->prog_attach_fn)
+			continue;
+
+		/* if user already set the link manually, don't attempt auto-attach */
+		if (*link)
+			continue;
+
+		err = prog->sec_def->prog_attach_fn(prog, prog->sec_def->cookie, link);
+		if (err) {
+			pr_warn("prog '%s': failed to auto-attach: %d\n",
+				bpf_program__name(prog), err);
+			return libbpf_err(err);
+		}
+
+		/* It's possible that for some SEC() definitions auto-attach
+		 * is supported in some cases (e.g., if definition completely
+		 * specifies target information), but is not in other cases.
+		 * SEC("uprobe") is one such case. If user specified target
+		 * binary and function name, such BPF program can be
+		 * auto-attached. But if not, it shouldn't trigger skeleton's
+		 * attach to fail. It should just be skipped.
+		 * attach_fn signals such case with returning 0 (no error) and
+		 * setting link to NULL.
+		 */
+	}
+
+	return 0;
+}
+
+void bpf_object__detach_skeleton(struct bpf_object_skeleton *s)
+{
+	int i;
+
+	for (i = 0; i < s->prog_cnt; i++) {
+		struct bpf_link **link = s->progs[i].link;
+
+		bpf_link__destroy(*link);
+		*link = NULL;
+	}
+}
+
+void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s)
+{
+	if (!s)
+		return;
+
+	if (s->progs)
+		bpf_object__detach_skeleton(s);
+	if (s->obj)
+		bpf_object__close(*s->obj);
+	free(s->maps);
+	free(s->progs);
+	free(s);
+}