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Commit ab9e0848 authored by Andrey Ignatov's avatar Andrey Ignatov Committed by Alexei Starovoitov
Browse files

libbpf: Per-symbol visibility for DSO 

Make global symbols in libbpf DSO hidden by default with
-fvisibility=hidden and export symbols that are part of ABI explicitly
with __attribute__((visibility("default"))).

This is common practice that should prevent from accidentally exporting
a symbol, that is not supposed to be a part of ABI what, in turn,
improves both libbpf developer- and user-experiences. See [1] for more
details.

Export control becomes more important since more and more projects use
libbpf.

The patch doesn't export a bunch of netlink related functions since as
agreed in [2] they'll be reworked. That doesn't break bpftool since
bpftool links libbpf statically.

[1] https://www.akkadia.org/drepper/dsohowto.pdf (2.2 Export Control)
[2] https://www.mail-archive.com/netdev@vger.kernel.org/msg251434.html



Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 421f4292

tools/lib/bpf/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -125,6 +125,7 @@ override CFLAGS += $(EXTRA_WARNINGS) 
override CFLAGS += -Werror -Wall

override CFLAGS += -fPIC

override CFLAGS += $(INCLUDES)

override CFLAGS += -fvisibility=hidden



ifeq ($(VERBOSE),1)

  Q =

tools/lib/bpf/bpf.h

+65 −53
Original line number Diff line number Diff line
@@ -27,6 +27,10 @@ 
#include <stdbool.h>

#include <stddef.h>



#ifndef LIBBPF_API

#define LIBBPF_API __attribute__((visibility("default")))

#endif



struct bpf_create_map_attr {

	const char *name;

	enum bpf_map_type map_type;
@@ -42,20 +46,23 @@ struct bpf_create_map_attr { 
	__u32 inner_map_fd;

};



int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr);

int bpf_create_map_node(enum bpf_map_type map_type, const char *name,

			int key_size, int value_size, int max_entries,

			__u32 map_flags, int node);

int bpf_create_map_name(enum bpf_map_type map_type, const char *name,

			int key_size, int value_size, int max_entries,

			__u32 map_flags);

int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size,

LIBBPF_API int

bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr);

LIBBPF_API int bpf_create_map_node(enum bpf_map_type map_type, const char *name,

				   int key_size, int value_size,

				   int max_entries, __u32 map_flags, int node);

LIBBPF_API int bpf_create_map_name(enum bpf_map_type map_type, const char *name,

				   int key_size, int value_size,

				   int max_entries, __u32 map_flags);

int bpf_create_map_in_map_node(enum bpf_map_type map_type, const char *name,

			       int key_size, int inner_map_fd, int max_entries,

LIBBPF_API int bpf_create_map(enum bpf_map_type map_type, int key_size,

			      int value_size, int max_entries, __u32 map_flags);

LIBBPF_API int bpf_create_map_in_map_node(enum bpf_map_type map_type,

					  const char *name, int key_size,

					  int inner_map_fd, int max_entries,

					  __u32 map_flags, int node);

int bpf_create_map_in_map(enum bpf_map_type map_type, const char *name,

			  int key_size, int inner_map_fd, int max_entries,

LIBBPF_API int bpf_create_map_in_map(enum bpf_map_type map_type,

				     const char *name, int key_size,

				     int inner_map_fd, int max_entries,

				     __u32 map_flags);



struct bpf_load_program_attr {
@@ -74,44 +81,49 @@ struct bpf_load_program_attr { 


/* Recommend log buffer size */

#define BPF_LOG_BUF_SIZE (256 * 1024)

int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,

LIBBPF_API int

bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,

		       char *log_buf, size_t log_buf_sz);

LIBBPF_API int bpf_load_program(enum bpf_prog_type type,

				const struct bpf_insn *insns, size_t insns_cnt,

				const char *license, __u32 kern_version,

				char *log_buf, size_t log_buf_sz);

int bpf_load_program(enum bpf_prog_type type, const struct bpf_insn *insns,

		     size_t insns_cnt, const char *license,

		     __u32 kern_version, char *log_buf,

		     size_t log_buf_sz);

int bpf_verify_program(enum bpf_prog_type type, const struct bpf_insn *insns,

LIBBPF_API int bpf_verify_program(enum bpf_prog_type type,

				  const struct bpf_insn *insns,

				  size_t insns_cnt, int strict_alignment,

				  const char *license, __u32 kern_version,

		       char *log_buf, size_t log_buf_sz, int log_level);

				  char *log_buf, size_t log_buf_sz,

				  int log_level);



int bpf_map_update_elem(int fd, const void *key, const void *value,

LIBBPF_API int bpf_map_update_elem(int fd, const void *key, const void *value,

				   __u64 flags);



int bpf_map_lookup_elem(int fd, const void *key, void *value);

int bpf_map_delete_elem(int fd, const void *key);

int bpf_map_get_next_key(int fd, const void *key, void *next_key);

int bpf_obj_pin(int fd, const char *pathname);

int bpf_obj_get(const char *pathname);

int bpf_prog_attach(int prog_fd, int attachable_fd, enum bpf_attach_type type,

		    unsigned int flags);

int bpf_prog_detach(int attachable_fd, enum bpf_attach_type type);

int bpf_prog_detach2(int prog_fd, int attachable_fd, enum bpf_attach_type type);

int bpf_prog_test_run(int prog_fd, int repeat, void *data, __u32 size,

		      void *data_out, __u32 *size_out, __u32 *retval,

		      __u32 *duration);

int bpf_prog_get_next_id(__u32 start_id, __u32 *next_id);

int bpf_map_get_next_id(__u32 start_id, __u32 *next_id);

int bpf_prog_get_fd_by_id(__u32 id);

int bpf_map_get_fd_by_id(__u32 id);

int bpf_btf_get_fd_by_id(__u32 id);

int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len);

int bpf_prog_query(int target_fd, enum bpf_attach_type type, __u32 query_flags,

		   __u32 *attach_flags, __u32 *prog_ids, __u32 *prog_cnt);

int bpf_raw_tracepoint_open(const char *name, int prog_fd);

int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf, __u32 log_buf_size,

		 bool do_log);

int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf, __u32 *buf_len,

		      __u32 *prog_id, __u32 *fd_type, __u64 *probe_offset,

		      __u64 *probe_addr);

LIBBPF_API int bpf_map_lookup_elem(int fd, const void *key, void *value);

LIBBPF_API int bpf_map_delete_elem(int fd, const void *key);

LIBBPF_API int bpf_map_get_next_key(int fd, const void *key, void *next_key);

LIBBPF_API int bpf_obj_pin(int fd, const char *pathname);

LIBBPF_API int bpf_obj_get(const char *pathname);

LIBBPF_API int bpf_prog_attach(int prog_fd, int attachable_fd,

			       enum bpf_attach_type type, unsigned int flags);

LIBBPF_API int bpf_prog_detach(int attachable_fd, enum bpf_attach_type type);

LIBBPF_API int bpf_prog_detach2(int prog_fd, int attachable_fd,

				enum bpf_attach_type type);

LIBBPF_API int bpf_prog_test_run(int prog_fd, int repeat, void *data,

				 __u32 size, void *data_out, __u32 *size_out,

				 __u32 *retval, __u32 *duration);

LIBBPF_API int bpf_prog_get_next_id(__u32 start_id, __u32 *next_id);

LIBBPF_API int bpf_map_get_next_id(__u32 start_id, __u32 *next_id);

LIBBPF_API int bpf_prog_get_fd_by_id(__u32 id);

LIBBPF_API int bpf_map_get_fd_by_id(__u32 id);

LIBBPF_API int bpf_btf_get_fd_by_id(__u32 id);

LIBBPF_API int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len);

LIBBPF_API int bpf_prog_query(int target_fd, enum bpf_attach_type type,

			      __u32 query_flags, __u32 *attach_flags,

			      __u32 *prog_ids, __u32 *prog_cnt);

LIBBPF_API int bpf_raw_tracepoint_open(const char *name, int prog_fd);

LIBBPF_API int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf,

			    __u32 log_buf_size, bool do_log);

LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,

				 __u32 *buf_len, __u32 *prog_id, __u32 *fd_type,

				 __u64 *probe_offset, __u64 *probe_addr);

#endif /* __LIBBPF_BPF_H */

tools/lib/bpf/btf.h

+14 −8
Original line number Diff line number Diff line
@@ -6,6 +6,10 @@ 


#include <linux/types.h>



#ifndef LIBBPF_API

#define LIBBPF_API __attribute__((visibility("default")))

#endif



#define BTF_ELF_SEC ".BTF"



struct btf;
@@ -14,13 +18,15 @@ struct btf_type; 
typedef int (*btf_print_fn_t)(const char *, ...)

	__attribute__((format(printf, 1, 2)));



void btf__free(struct btf *btf);

struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log);

__s32 btf__find_by_name(const struct btf *btf, const char *type_name);

const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 id);

__s64 btf__resolve_size(const struct btf *btf, __u32 type_id);

int btf__resolve_type(const struct btf *btf, __u32 type_id);

int btf__fd(const struct btf *btf);

const char *btf__name_by_offset(const struct btf *btf, __u32 offset);

LIBBPF_API void btf__free(struct btf *btf);

LIBBPF_API struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log);

LIBBPF_API __s32 btf__find_by_name(const struct btf *btf,

				   const char *type_name);

LIBBPF_API const struct btf_type *btf__type_by_id(const struct btf *btf,

						  __u32 id);

LIBBPF_API __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);

LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);

LIBBPF_API int btf__fd(const struct btf *btf);

LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);



#endif /* __LIBBPF_BTF_H */

tools/lib/bpf/libbpf.h

+99 −87
Original line number Diff line number Diff line
@@ -16,6 +16,10 @@ 
#include <sys/types.h>  // for size_t

#include <linux/bpf.h>



#ifndef LIBBPF_API

#define LIBBPF_API __attribute__((visibility("default")))

#endif



enum libbpf_errno {

	__LIBBPF_ERRNO__START = 4000,
@@ -37,7 +41,7 @@ enum libbpf_errno { 
	__LIBBPF_ERRNO__END,

};



int libbpf_strerror(int err, char *buf, size_t size);

LIBBPF_API int libbpf_strerror(int err, char *buf, size_t size);



/*

 * __printf is defined in include/linux/compiler-gcc.h. However,
@@ -47,7 +51,7 @@ int libbpf_strerror(int err, char *buf, size_t size); 
typedef int (*libbpf_print_fn_t)(const char *, ...)

	__attribute__((format(printf, 1, 2)));



void libbpf_set_print(libbpf_print_fn_t warn,

LIBBPF_API void libbpf_set_print(libbpf_print_fn_t warn,

				 libbpf_print_fn_t info,

				 libbpf_print_fn_t debug);
@@ -59,27 +63,28 @@ struct bpf_object_open_attr { 
	enum bpf_prog_type prog_type;

};



struct bpf_object *bpf_object__open(const char *path);

struct bpf_object *bpf_object__open_xattr(struct bpf_object_open_attr *attr);

LIBBPF_API struct bpf_object *bpf_object__open(const char *path);

LIBBPF_API struct bpf_object *

bpf_object__open_xattr(struct bpf_object_open_attr *attr);

struct bpf_object *__bpf_object__open_xattr(struct bpf_object_open_attr *attr,

					    int flags);

struct bpf_object *bpf_object__open_buffer(void *obj_buf,

LIBBPF_API struct bpf_object *bpf_object__open_buffer(void *obj_buf,

						      size_t obj_buf_sz,

						      const char *name);

int bpf_object__pin(struct bpf_object *object, const char *path);

void bpf_object__close(struct bpf_object *object);

LIBBPF_API int bpf_object__pin(struct bpf_object *object, const char *path);

LIBBPF_API void bpf_object__close(struct bpf_object *object);



/* Load/unload object into/from kernel */

int bpf_object__load(struct bpf_object *obj);

int bpf_object__unload(struct bpf_object *obj);

const char *bpf_object__name(struct bpf_object *obj);

unsigned int bpf_object__kversion(struct bpf_object *obj);

int bpf_object__btf_fd(const struct bpf_object *obj);

LIBBPF_API int bpf_object__load(struct bpf_object *obj);

LIBBPF_API int bpf_object__unload(struct bpf_object *obj);

LIBBPF_API const char *bpf_object__name(struct bpf_object *obj);

LIBBPF_API unsigned int bpf_object__kversion(struct bpf_object *obj);

LIBBPF_API int bpf_object__btf_fd(const struct bpf_object *obj);



struct bpf_program *

LIBBPF_API struct bpf_program *

bpf_object__find_program_by_title(struct bpf_object *obj, const char *title);



struct bpf_object *bpf_object__next(struct bpf_object *prev);

LIBBPF_API struct bpf_object *bpf_object__next(struct bpf_object *prev);

#define bpf_object__for_each_safe(pos, tmp)			\

	for ((pos) = bpf_object__next(NULL),		\

		(tmp) = bpf_object__next(pos);		\
@@ -87,18 +92,19 @@ struct bpf_object *bpf_object__next(struct bpf_object *prev); 
	     (pos) = (tmp), (tmp) = bpf_object__next(tmp))



typedef void (*bpf_object_clear_priv_t)(struct bpf_object *, void *);

int bpf_object__set_priv(struct bpf_object *obj, void *priv,

LIBBPF_API int bpf_object__set_priv(struct bpf_object *obj, void *priv,

				    bpf_object_clear_priv_t clear_priv);

void *bpf_object__priv(struct bpf_object *prog);

LIBBPF_API void *bpf_object__priv(struct bpf_object *prog);



int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,

LIBBPF_API int

libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,

			 enum bpf_attach_type *expected_attach_type);

int libbpf_attach_type_by_name(const char *name,

LIBBPF_API int libbpf_attach_type_by_name(const char *name,

					  enum bpf_attach_type *attach_type);



/* Accessors of bpf_program */

struct bpf_program;

struct bpf_program *bpf_program__next(struct bpf_program *prog,

LIBBPF_API struct bpf_program *bpf_program__next(struct bpf_program *prog,

						 struct bpf_object *obj);



#define bpf_object__for_each_program(pos, obj)		\
@@ -109,21 +115,24 @@ struct bpf_program *bpf_program__next(struct bpf_program *prog, 
typedef void (*bpf_program_clear_priv_t)(struct bpf_program *,

					 void *);



int bpf_program__set_priv(struct bpf_program *prog, void *priv,

LIBBPF_API int bpf_program__set_priv(struct bpf_program *prog, void *priv,

				     bpf_program_clear_priv_t clear_priv);



void *bpf_program__priv(struct bpf_program *prog);

void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex);

LIBBPF_API void *bpf_program__priv(struct bpf_program *prog);

LIBBPF_API void bpf_program__set_ifindex(struct bpf_program *prog,

					 __u32 ifindex);



const char *bpf_program__title(struct bpf_program *prog, bool needs_copy);

LIBBPF_API const char *bpf_program__title(struct bpf_program *prog,

					  bool needs_copy);



int bpf_program__load(struct bpf_program *prog, char *license,

LIBBPF_API int bpf_program__load(struct bpf_program *prog, char *license,

				 __u32 kern_version);

int bpf_program__fd(struct bpf_program *prog);

int bpf_program__pin_instance(struct bpf_program *prog, const char *path,

LIBBPF_API int bpf_program__fd(struct bpf_program *prog);

LIBBPF_API int bpf_program__pin_instance(struct bpf_program *prog,

					 const char *path,

					 int instance);

int bpf_program__pin(struct bpf_program *prog, const char *path);

void bpf_program__unload(struct bpf_program *prog);

LIBBPF_API int bpf_program__pin(struct bpf_program *prog, const char *path);

LIBBPF_API void bpf_program__unload(struct bpf_program *prog);



struct bpf_insn;
@@ -184,34 +193,36 @@ typedef int (*bpf_program_prep_t)(struct bpf_program *prog, int n, 
				  struct bpf_insn *insns, int insns_cnt,

				  struct bpf_prog_prep_result *res);



int bpf_program__set_prep(struct bpf_program *prog, int nr_instance,

LIBBPF_API int bpf_program__set_prep(struct bpf_program *prog, int nr_instance,

				     bpf_program_prep_t prep);



int bpf_program__nth_fd(struct bpf_program *prog, int n);

LIBBPF_API int bpf_program__nth_fd(struct bpf_program *prog, int n);



/*

 * Adjust type of BPF program. Default is kprobe.

 */

int bpf_program__set_socket_filter(struct bpf_program *prog);

int bpf_program__set_tracepoint(struct bpf_program *prog);

int bpf_program__set_raw_tracepoint(struct bpf_program *prog);

int bpf_program__set_kprobe(struct bpf_program *prog);

int bpf_program__set_sched_cls(struct bpf_program *prog);

int bpf_program__set_sched_act(struct bpf_program *prog);

int bpf_program__set_xdp(struct bpf_program *prog);

int bpf_program__set_perf_event(struct bpf_program *prog);

void bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type);

void bpf_program__set_expected_attach_type(struct bpf_program *prog,

LIBBPF_API int bpf_program__set_socket_filter(struct bpf_program *prog);

LIBBPF_API int bpf_program__set_tracepoint(struct bpf_program *prog);

LIBBPF_API int bpf_program__set_raw_tracepoint(struct bpf_program *prog);

LIBBPF_API int bpf_program__set_kprobe(struct bpf_program *prog);

LIBBPF_API int bpf_program__set_sched_cls(struct bpf_program *prog);

LIBBPF_API int bpf_program__set_sched_act(struct bpf_program *prog);

LIBBPF_API int bpf_program__set_xdp(struct bpf_program *prog);

LIBBPF_API int bpf_program__set_perf_event(struct bpf_program *prog);

LIBBPF_API void bpf_program__set_type(struct bpf_program *prog,

				      enum bpf_prog_type type);

LIBBPF_API void

bpf_program__set_expected_attach_type(struct bpf_program *prog,

				      enum bpf_attach_type type);



bool bpf_program__is_socket_filter(struct bpf_program *prog);

bool bpf_program__is_tracepoint(struct bpf_program *prog);

bool bpf_program__is_raw_tracepoint(struct bpf_program *prog);

bool bpf_program__is_kprobe(struct bpf_program *prog);

bool bpf_program__is_sched_cls(struct bpf_program *prog);

bool bpf_program__is_sched_act(struct bpf_program *prog);

bool bpf_program__is_xdp(struct bpf_program *prog);

bool bpf_program__is_perf_event(struct bpf_program *prog);

LIBBPF_API bool bpf_program__is_socket_filter(struct bpf_program *prog);

LIBBPF_API bool bpf_program__is_tracepoint(struct bpf_program *prog);

LIBBPF_API bool bpf_program__is_raw_tracepoint(struct bpf_program *prog);

LIBBPF_API bool bpf_program__is_kprobe(struct bpf_program *prog);

LIBBPF_API bool bpf_program__is_sched_cls(struct bpf_program *prog);

LIBBPF_API bool bpf_program__is_sched_act(struct bpf_program *prog);

LIBBPF_API bool bpf_program__is_xdp(struct bpf_program *prog);

LIBBPF_API bool bpf_program__is_perf_event(struct bpf_program *prog);



/*

 * No need for __attribute__((packed)), all members of 'bpf_map_def'
@@ -232,39 +243,39 @@ struct bpf_map_def { 
 * so no need to worry about a name clash.

 */

struct bpf_map;

struct bpf_map *

LIBBPF_API struct bpf_map *

bpf_object__find_map_by_name(struct bpf_object *obj, const char *name);



/*

 * Get bpf_map through the offset of corresponding struct bpf_map_def

 * in the BPF object file.

 */

struct bpf_map *

LIBBPF_API struct bpf_map *

bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset);



struct bpf_map *

LIBBPF_API struct bpf_map *

bpf_map__next(struct bpf_map *map, struct bpf_object *obj);

#define bpf_map__for_each(pos, obj)		\

	for ((pos) = bpf_map__next(NULL, (obj));	\

	     (pos) != NULL;				\

	     (pos) = bpf_map__next((pos), (obj)))



int bpf_map__fd(struct bpf_map *map);

const struct bpf_map_def *bpf_map__def(struct bpf_map *map);

const char *bpf_map__name(struct bpf_map *map);

__u32 bpf_map__btf_key_type_id(const struct bpf_map *map);

__u32 bpf_map__btf_value_type_id(const struct bpf_map *map);

LIBBPF_API int bpf_map__fd(struct bpf_map *map);

LIBBPF_API const struct bpf_map_def *bpf_map__def(struct bpf_map *map);

LIBBPF_API const char *bpf_map__name(struct bpf_map *map);

LIBBPF_API __u32 bpf_map__btf_key_type_id(const struct bpf_map *map);

LIBBPF_API __u32 bpf_map__btf_value_type_id(const struct bpf_map *map);



typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);

int bpf_map__set_priv(struct bpf_map *map, void *priv,

LIBBPF_API int bpf_map__set_priv(struct bpf_map *map, void *priv,

				 bpf_map_clear_priv_t clear_priv);

void *bpf_map__priv(struct bpf_map *map);

int bpf_map__reuse_fd(struct bpf_map *map, int fd);

bool bpf_map__is_offload_neutral(struct bpf_map *map);

void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex);

int bpf_map__pin(struct bpf_map *map, const char *path);

LIBBPF_API void *bpf_map__priv(struct bpf_map *map);

LIBBPF_API int bpf_map__reuse_fd(struct bpf_map *map, int fd);

LIBBPF_API bool bpf_map__is_offload_neutral(struct bpf_map *map);

LIBBPF_API void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex);

LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path);



long libbpf_get_error(const void *ptr);

LIBBPF_API long libbpf_get_error(const void *ptr);



struct bpf_prog_load_attr {

	const char *file;
@@ -273,12 +284,12 @@ struct bpf_prog_load_attr { 
	int ifindex;

};



int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,

LIBBPF_API int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,

				   struct bpf_object **pobj, int *prog_fd);

int bpf_prog_load(const char *file, enum bpf_prog_type type,

LIBBPF_API int bpf_prog_load(const char *file, enum bpf_prog_type type,

			     struct bpf_object **pobj, int *prog_fd);



int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags);

LIBBPF_API int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags);



enum bpf_perf_event_ret {

	LIBBPF_PERF_EVENT_DONE	= 0,
@@ -288,10 +299,11 @@ enum bpf_perf_event_ret { 


typedef enum bpf_perf_event_ret (*bpf_perf_event_print_t)(void *event,

							  void *priv);

int bpf_perf_event_read_simple(void *mem, unsigned long size,

LIBBPF_API int bpf_perf_event_read_simple(void *mem, unsigned long size,

					  unsigned long page_size,

					  void **buf, size_t *buf_len,

			       bpf_perf_event_print_t fn, void *priv);

					  bpf_perf_event_print_t fn,

					  void *priv);



struct nlattr;

typedef int (*libbpf_dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);