diff options
| -rw-r--r-- | tools/lib/bpf/elf.c | 110 | ||||
| -rw-r--r-- | tools/lib/bpf/libbpf_internal.h | 2 |
2 files changed, 112 insertions, 0 deletions
diff --git a/tools/lib/bpf/elf.c b/tools/lib/bpf/elf.c index 8a3f8a725981..8c512641c1d7 100644 --- a/tools/lib/bpf/elf.c +++ b/tools/lib/bpf/elf.c @@ -267,3 +267,113 @@ long elf_find_func_offset_from_file(const char *binary_path, const char *name) elf_close(&elf_fd); return ret; } + +struct symbol { + const char *name; + int bind; + int idx; +}; + +static int symbol_cmp(const void *a, const void *b) +{ + const struct symbol *sym_a = a; + const struct symbol *sym_b = b; + + return strcmp(sym_a->name, sym_b->name); +} + +/* + * Return offsets in @poffsets for symbols specified in @syms array argument. + * On success returns 0 and offsets are returned in allocated array with @cnt + * size, that needs to be released by the caller. + */ +int elf_resolve_syms_offsets(const char *binary_path, int cnt, + const char **syms, unsigned long **poffsets) +{ + int sh_types[2] = { SHT_DYNSYM, SHT_SYMTAB }; + int err = 0, i, cnt_done = 0; + unsigned long *offsets; + struct symbol *symbols; + struct elf_fd elf_fd; + + err = elf_open(binary_path, &elf_fd); + if (err) + return err; + + offsets = calloc(cnt, sizeof(*offsets)); + symbols = calloc(cnt, sizeof(*symbols)); + + if (!offsets || !symbols) { + err = -ENOMEM; + goto out; + } + + for (i = 0; i < cnt; i++) { + symbols[i].name = syms[i]; + symbols[i].idx = i; + } + + qsort(symbols, cnt, sizeof(*symbols), symbol_cmp); + + 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))) { + unsigned long sym_offset = elf_sym_offset(sym); + int bind = GELF_ST_BIND(sym->sym.st_info); + struct symbol *found, tmp = { + .name = sym->name, + }; + unsigned long *offset; + + found = bsearch(&tmp, symbols, cnt, sizeof(*symbols), symbol_cmp); + if (!found) + continue; + + offset = &offsets[found->idx]; + if (*offset > 0) { + /* same offset, no problem */ + if (*offset == sym_offset) + continue; + /* handle multiple matches */ + if (found->bind != STB_WEAK && bind != STB_WEAK) { + /* Only accept one non-weak bind. */ + pr_warn("elf: ambiguous match found '%s@%lu' in '%s' previous offset %lu\n", + sym->name, sym_offset, binary_path, *offset); + err = -ESRCH; + goto out; + } else if (bind == STB_WEAK) { + /* already have a non-weak bind, and + * this is a weak bind, so ignore. + */ + continue; + } + } else { + cnt_done++; + } + *offset = sym_offset; + found->bind = bind; + } + } + + if (cnt != cnt_done) { + err = -ENOENT; + goto out; + } + + *poffsets = offsets; + +out: + free(symbols); + if (err) + free(offsets); + elf_close(&elf_fd); + return err; +} diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 0bbcd8e6fdc5..92851c5f912d 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -589,4 +589,6 @@ struct elf_fd { int elf_open(const char *binary_path, struct elf_fd *elf_fd); 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); #endif /* __LIBBPF_LIBBPF_INTERNAL_H */ |