Commit e613d1d0 authored by Jiri Olsa's avatar Jiri Olsa Committed by Alexei Starovoitov
Browse files

libbpf: Add elf_resolve_pattern_offsets function 



Adding elf_resolve_pattern_offsets function that looks up
offsets for symbols specified by pattern argument.

The 'pattern' argument allows wildcards (*?' supported).

Offsets are returned in allocated array together with its
size and needs to be released by the caller.

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230809083440.3209381-13-jolsa@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 7ace84c6

tools/lib/bpf/elf.c

+61 −0
Original line number Diff line number Diff line
@@ -377,3 +377,64 @@ int elf_resolve_syms_offsets(const char *binary_path, int cnt, 
	elf_close(&elf_fd);

	return err;

}



/*

 * Return offsets in @poffsets for symbols specified by @pattern argument.

 * On success returns 0 and offsets are returned in allocated @poffsets

 * array with the @pctn size, that needs to be released by the caller.

 */

int elf_resolve_pattern_offsets(const char *binary_path, const char *pattern,

				unsigned long **poffsets, size_t *pcnt)

{

	int sh_types[2] = { SHT_SYMTAB, SHT_DYNSYM };

	unsigned long *offsets = NULL;

	size_t cap = 0, cnt = 0;

	struct elf_fd elf_fd;

	int err = 0, i;



	err = elf_open(binary_path, &elf_fd);

	if (err)

		return err;



	for (i = 0; i < ARRAY_SIZE(sh_types); i++) {

		struct elf_sym_iter iter;

		struct elf_sym *sym;



		err = elf_sym_iter_new(&iter, elf_fd.elf, binary_path, sh_types[i], STT_FUNC);

		if (err == -ENOENT)

			continue;

		if (err)

			goto out;



		while ((sym = elf_sym_iter_next(&iter))) {

			if (!glob_match(sym->name, pattern))

				continue;



			err = libbpf_ensure_mem((void **) &offsets, &cap, sizeof(*offsets),

						cnt + 1);

			if (err)

				goto out;



			offsets[cnt++] = elf_sym_offset(sym);

		}



		/* If we found anything in the first symbol section,

		 * do not search others to avoid duplicates.

		 */

		if (cnt)

			break;

	}



	if (cnt) {

		*poffsets = offsets;

		*pcnt = cnt;

	} else {

		err = -ENOENT;

	}



out:

	if (err)

		free(offsets);

	elf_close(&elf_fd);

	return err;

}

tools/lib/bpf/libbpf.c

+1 −1
Original line number Diff line number Diff line
@@ -10569,7 +10569,7 @@ struct bpf_link *bpf_program__attach_ksyscall(const struct bpf_program *prog, 
}



/* Adapted from perf/util/string.c */

static bool glob_match(const char *str, const char *pat)

bool glob_match(const char *str, const char *pat)

{

	while (*str && *pat && *pat != '*') {

		if (*pat == '?') {      /* Matches any single character */

tools/lib/bpf/libbpf_internal.h

+5 −0
Original line number Diff line number Diff line
@@ -578,6 +578,8 @@ static inline bool is_pow_of_2(size_t x) 
#define PROG_LOAD_ATTEMPTS 5

int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts);



bool glob_match(const char *str, const char *pat);



long elf_find_func_offset(Elf *elf, const char *binary_path, const char *name);

long elf_find_func_offset_from_file(const char *binary_path, const char *name);
@@ -591,4 +593,7 @@ void elf_close(struct elf_fd *elf_fd); 


int elf_resolve_syms_offsets(const char *binary_path, int cnt,

			     const char **syms, unsigned long **poffsets);

int elf_resolve_pattern_offsets(const char *binary_path, const char *pattern,

				 unsigned long **poffsets, size_t *pcnt);



#endif /* __LIBBPF_LIBBPF_INTERNAL_H */