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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: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
hifive-unleashed-5.1
Andrey Ignatov 2018-10-15 22:50:34 -07:00 committed by Alexei Starovoitov
parent 421f4292f4
commit ab9e084821
4 changed files with 178 additions and 147 deletions

View File

@ -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 =

View File

@ -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;
@ -42,21 +46,24 @@ 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,
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,
__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,
__u32 map_flags);
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);
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);
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 {
enum bpf_prog_type prog_type;
@ -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,
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,
size_t insns_cnt, int strict_alignment,
const char *license, __u32 kern_version,
char *log_buf, size_t log_buf_sz, int log_level);
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);
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);
int bpf_map_update_elem(int fd, const void *key, const void *value,
__u64 flags);
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 */

View File

@ -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 */

View File

@ -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,
@ -47,9 +51,9 @@ 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_print_fn_t info,
libbpf_print_fn_t debug);
LIBBPF_API void libbpf_set_print(libbpf_print_fn_t warn,
libbpf_print_fn_t info,
libbpf_print_fn_t debug);
/* Hide internal to user */
struct bpf_object;
@ -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,
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 struct bpf_object *bpf_object__open_buffer(void *obj_buf,
size_t obj_buf_sz,
const char *name);
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); \
@ -87,19 +92,20 @@ 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,
bpf_object_clear_priv_t clear_priv);
void *bpf_object__priv(struct bpf_object *prog);
LIBBPF_API int bpf_object__set_priv(struct bpf_object *obj, void *priv,
bpf_object_clear_priv_t clear_priv);
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,
enum bpf_attach_type *expected_attach_type);
int libbpf_attach_type_by_name(const char *name,
enum bpf_attach_type *attach_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);
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,
struct bpf_object *obj);
LIBBPF_API struct bpf_program *bpf_program__next(struct bpf_program *prog,
struct bpf_object *obj);
#define bpf_object__for_each_program(pos, obj) \
for ((pos) = bpf_program__next(NULL, (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,
bpf_program_clear_priv_t clear_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,
__u32 kern_version);
int bpf_program__fd(struct bpf_program *prog);
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__load(struct bpf_program *prog, char *license,
__u32 kern_version);
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);
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,
bpf_program_prep_t prep);
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,
enum bpf_attach_type type);
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,
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 int bpf_map__set_priv(struct bpf_map *map, void *priv,
bpf_map_clear_priv_t clear_priv);
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,
struct bpf_object **pobj, int *prog_fd);
int bpf_prog_load(const char *file, enum bpf_prog_type type,
struct bpf_object **pobj, int *prog_fd);
LIBBPF_API int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
struct bpf_object **pobj, int *prog_fd);
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,
unsigned long page_size,
void **buf, size_t *buf_len,
bpf_perf_event_print_t fn, void *priv);
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);
struct nlattr;
typedef int (*libbpf_dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);