#include #include #include #include #include #include #include #include #include #include "symbol.h" #include "debug.h" #ifndef NT_GNU_BUILD_ID #define NT_GNU_BUILD_ID 3 #endif /** * elf_symtab__for_each_symbol - iterate thru all the symbols * * @syms: struct elf_symtab instance to iterate * @idx: uint32_t idx * @sym: GElf_Sym iterator */ #define elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) \ for (idx = 0, gelf_getsym(syms, idx, &sym);\ idx < nr_syms; \ idx++, gelf_getsym(syms, idx, &sym)) static inline uint8_t elf_sym__type(const GElf_Sym *sym) { return GELF_ST_TYPE(sym->st_info); } static inline int elf_sym__is_function(const GElf_Sym *sym) { return elf_sym__type(sym) == STT_FUNC && sym->st_name != 0 && sym->st_shndx != SHN_UNDEF; } static inline bool elf_sym__is_object(const GElf_Sym *sym) { return elf_sym__type(sym) == STT_OBJECT && sym->st_name != 0 && sym->st_shndx != SHN_UNDEF; } static inline int elf_sym__is_label(const GElf_Sym *sym) { return elf_sym__type(sym) == STT_NOTYPE && sym->st_name != 0 && sym->st_shndx != SHN_UNDEF && sym->st_shndx != SHN_ABS; } static bool elf_sym__is_a(GElf_Sym *sym, enum map_type type) { switch (type) { case MAP__FUNCTION: return elf_sym__is_function(sym); case MAP__VARIABLE: return elf_sym__is_object(sym); default: return false; } } static inline const char *elf_sym__name(const GElf_Sym *sym, const Elf_Data *symstrs) { return symstrs->d_buf + sym->st_name; } static inline const char *elf_sec__name(const GElf_Shdr *shdr, const Elf_Data *secstrs) { return secstrs->d_buf + shdr->sh_name; } static inline int elf_sec__is_text(const GElf_Shdr *shdr, const Elf_Data *secstrs) { return strstr(elf_sec__name(shdr, secstrs), "text") != NULL; } static inline bool elf_sec__is_data(const GElf_Shdr *shdr, const Elf_Data *secstrs) { return strstr(elf_sec__name(shdr, secstrs), "data") != NULL; } static bool elf_sec__is_a(GElf_Shdr *shdr, Elf_Data *secstrs, enum map_type type) { switch (type) { case MAP__FUNCTION: return elf_sec__is_text(shdr, secstrs); case MAP__VARIABLE: return elf_sec__is_data(shdr, secstrs); default: return false; } } static size_t elf_addr_to_index(Elf *elf, GElf_Addr addr) { Elf_Scn *sec = NULL; GElf_Shdr shdr; size_t cnt = 1; while ((sec = elf_nextscn(elf, sec)) != NULL) { gelf_getshdr(sec, &shdr); if ((addr >= shdr.sh_addr) && (addr < (shdr.sh_addr + shdr.sh_size))) return cnt; ++cnt; } return -1; } static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep, GElf_Shdr *shp, const char *name, size_t *idx) { Elf_Scn *sec = NULL; size_t cnt = 1; /* Elf is corrupted/truncated, avoid calling elf_strptr. */ if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) return NULL; while ((sec = elf_nextscn(elf, sec)) != NULL) { char *str; gelf_getshdr(sec, shp); str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name); if (!strcmp(name, str)) { if (idx) *idx = cnt; break; } ++cnt; } return sec; } #define elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_entries) \ for (idx = 0, pos = gelf_getrel(reldata, 0, &pos_mem); \ idx < nr_entries; \ ++idx, pos = gelf_getrel(reldata, idx, &pos_mem)) #define elf_section__for_each_rela(reldata, pos, pos_mem, idx, nr_entries) \ for (idx = 0, pos = gelf_getrela(reldata, 0, &pos_mem); \ idx < nr_entries; \ ++idx, pos = gelf_getrela(reldata, idx, &pos_mem)) /* * We need to check if we have a .dynsym, so that we can handle the * .plt, synthesizing its symbols, that aren't on the symtabs (be it * .dynsym or .symtab). * And always look at the original dso, not at debuginfo packages, that * have the PLT data stripped out (shdr_rel_plt.sh_type == SHT_NOBITS). */ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss, struct map *map, symbol_filter_t filter) { uint32_t nr_rel_entries, idx; GElf_Sym sym; u64 plt_offset; GElf_Shdr shdr_plt; struct symbol *f; GElf_Shdr shdr_rel_plt, shdr_dynsym; Elf_Data *reldata, *syms, *symstrs; Elf_Scn *scn_plt_rel, *scn_symstrs, *scn_dynsym; size_t dynsym_idx; GElf_Ehdr ehdr; char sympltname[1024]; Elf *elf; int nr = 0, symidx, err = 0; if (!ss->dynsym) return 0; elf = ss->elf; ehdr = ss->ehdr; scn_dynsym = ss->dynsym; shdr_dynsym = ss->dynshdr; dynsym_idx = ss->dynsym_idx; if (scn_dynsym == NULL) goto out_elf_end; scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt, ".rela.plt", NULL); if (scn_plt_rel == NULL) { scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt, ".rel.plt", NULL); if (scn_plt_rel == NULL) goto out_elf_end; } err = -1; if (shdr_rel_plt.sh_link != dynsym_idx) goto out_elf_end; if (elf_section_by_name(elf, &ehdr, &shdr_plt, ".plt", NULL) == NULL) goto out_elf_end; /* * Fetch the relocation section to find the idxes to the GOT * and the symbols in the .dynsym they refer to. */ reldata = elf_getdata(scn_plt_rel, NULL); if (reldata == NULL) goto out_elf_end; syms = elf_getdata(scn_dynsym, NULL); if (syms == NULL) goto out_elf_end; scn_symstrs = elf_getscn(elf, shdr_dynsym.sh_link); if (scn_symstrs == NULL) goto out_elf_end; symstrs = elf_getdata(scn_symstrs, NULL); if (symstrs == NULL) goto out_elf_end; if (symstrs->d_size == 0) goto out_elf_end; nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize; plt_offset = shdr_plt.sh_offset; if (shdr_rel_plt.sh_type == SHT_RELA) { GElf_Rela pos_mem, *pos; elf_section__for_each_rela(reldata, pos, pos_mem, idx, nr_rel_entries) { symidx = GELF_R_SYM(pos->r_info); plt_offset += shdr_plt.sh_entsize; gelf_getsym(syms, symidx, &sym); snprintf(sympltname, sizeof(sympltname), "%s@plt", elf_sym__name(&sym, symstrs)); f = symbol__new(plt_offset, shdr_plt.sh_entsize, STB_GLOBAL, sympltname); if (!f) goto out_elf_end; if (filter && filter(map, f)) symbol__delete(f); else { symbols__insert(&dso->symbols[map->type], f); ++nr; } } } else if (shdr_rel_plt.sh_type == SHT_REL) { GElf_Rel pos_mem, *pos; elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_rel_entries) { symidx = GELF_R_SYM(pos->r_info); plt_offset += shdr_plt.sh_entsize; gelf_getsym(syms, symidx, &sym); snprintf(sympltname, sizeof(sympltname), "%s@plt", elf_sym__name(&sym, symstrs)); f = symbol__new(plt_offset, shdr_plt.sh_entsize, STB_GLOBAL, sympltname); if (!f) goto out_elf_end; if (filter && filter(map, f)) symbol__delete(f); else { symbols__insert(&dso->symbols[map->type], f); ++nr; } } } err = 0; out_elf_end: if (err == 0) return nr; pr_debug("%s: problems reading %s PLT info.\n", __func__, dso->long_name); return 0; } /* * Align offset to 4 bytes as needed for note name and descriptor data. */ #define NOTE_ALIGN(n) (((n) + 3) & -4U) static int elf_read_build_id(Elf *elf, void *bf, size_t size) { int err = -1; GElf_Ehdr ehdr; GElf_Shdr shdr; Elf_Data *data; Elf_Scn *sec; Elf_Kind ek; void *ptr; if (size < BUILD_ID_SIZE) goto out; ek = elf_kind(elf); if (ek != ELF_K_ELF) goto out; if (gelf_getehdr(elf, &ehdr) == NULL) { pr_err("%s: cannot get elf header.\n", __func__); goto out; } /* * Check following sections for notes: * '.note.gnu.build-id' * '.notes' * '.note' (VDSO specific) */ do { sec = elf_section_by_name(elf, &ehdr, &shdr, ".note.gnu.build-id", NULL); if (sec) break; sec = elf_section_by_name(elf, &ehdr, &shdr, ".notes", NULL); if (sec) break; sec = elf_section_by_name(elf, &ehdr, &shdr, ".note", NULL); if (sec) break; return err; } while (0); data = elf_getdata(sec, NULL); if (data == NULL) goto out; ptr = data->d_buf; while (ptr < (data->d_buf + data->d_size)) { GElf_Nhdr *nhdr = ptr; size_t namesz = NOTE_ALIGN(nhdr->n_namesz), descsz = NOTE_ALIGN(nhdr->n_descsz); const char *name; ptr += sizeof(*nhdr); name = ptr; ptr += namesz; if (nhdr->n_type == NT_GNU_BUILD_ID && nhdr->n_namesz == sizeof("GNU")) { if (memcmp(name, "GNU", sizeof("GNU")) == 0) { size_t sz = min(size, descsz); memcpy(bf, ptr, sz); memset(bf + sz, 0, size - sz); err = descsz; break; } } ptr += descsz; } out: return err; } int filename__read_build_id(const char *filename, void *bf, size_t size) { int fd, err = -1; Elf *elf; if (size < BUILD_ID_SIZE) goto out; fd = open(filename, O_RDONLY); if (fd < 0) goto out; elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); if (elf == NULL) { pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename); goto out_close; } err = elf_read_build_id(elf, bf, size); elf_end(elf); out_close: close(fd); out: return err; } int sysfs__read_build_id(const char *filename, void *build_id, size_t size) { int fd, err = -1; if (size < BUILD_ID_SIZE) goto out; fd = open(filename, O_RDONLY); if (fd < 0) goto out; while (1) { char bf[BUFSIZ]; GElf_Nhdr nhdr; size_t namesz, descsz; if (read(fd, &nhdr, sizeof(nhdr)) != sizeof(nhdr)) break; namesz = NOTE_ALIGN(nhdr.n_namesz); descsz = NOTE_ALIGN(nhdr.n_descsz); if (nhdr.n_type == NT_GNU_BUILD_ID && nhdr.n_namesz == sizeof("GNU")) { if (read(fd, bf, namesz) != (ssize_t)namesz) break; if (memcmp(bf, "GNU", sizeof("GNU")) == 0) { size_t sz = min(descsz, size); if (read(fd, build_id, sz) == (ssize_t)sz) { memset(build_id + sz, 0, size - sz); err = 0; break; } } else if (read(fd, bf, descsz) != (ssize_t)descsz) break; } else { int n = namesz + descsz; if (read(fd, bf, n) != n) break; } } close(fd); out: return err; } int filename__read_debuglink(const char *filename, char *debuglink, size_t size) { int fd, err = -1; Elf *elf; GElf_Ehdr ehdr; GElf_Shdr shdr; Elf_Data *data; Elf_Scn *sec; Elf_Kind ek; fd = open(filename, O_RDONLY); if (fd < 0) goto out; elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); if (elf == NULL) { pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename); goto out_close; } ek = elf_kind(elf); if (ek != ELF_K_ELF) goto out_close; if (gelf_getehdr(elf, &ehdr) == NULL) { pr_err("%s: cannot get elf header.\n", __func__); goto out_close; } sec = elf_section_by_name(elf, &ehdr, &shdr, ".gnu_debuglink", NULL); if (sec == NULL) goto out_close; data = elf_getdata(sec, NULL); if (data == NULL) goto out_close; /* the start of this section is a zero-terminated string */ strncpy(debuglink, data->d_buf, size); elf_end(elf); out_close: close(fd); out: return err; } static int dso__swap_init(struct dso *dso, unsigned char eidata) { static unsigned int const endian = 1; dso->needs_swap = DSO_SWAP__NO; switch (eidata) { case ELFDATA2LSB: /* We are big endian, DSO is little endian. */ if (*(unsigned char const *)&endian != 1) dso->needs_swap = DSO_SWAP__YES; break; case ELFDATA2MSB: /* We are little endian, DSO is big endian. */ if (*(unsigned char const *)&endian != 0) dso->needs_swap = DSO_SWAP__YES; break; default: pr_err("unrecognized DSO data encoding %d\n", eidata); return -EINVAL; } return 0; } bool symsrc__possibly_runtime(struct symsrc *ss) { return ss->dynsym || ss->opdsec; } bool symsrc__has_symtab(struct symsrc *ss) { return ss->symtab != NULL; } void symsrc__destroy(struct symsrc *ss) { free(ss->name); elf_end(ss->elf); close(ss->fd); } int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, enum dso_binary_type type) { int err = -1; GElf_Ehdr ehdr; Elf *elf; int fd; fd = open(name, O_RDONLY); if (fd < 0) return -1; elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); if (elf == NULL) { pr_debug("%s: cannot read %s ELF file.\n", __func__, name); goto out_close; } if (gelf_getehdr(elf, &ehdr) == NULL) { pr_debug("%s: cannot get elf header.\n", __func__); goto out_elf_end; } if (dso__swap_init(dso, ehdr.e_ident[EI_DATA])) goto out_elf_end; /* Always reject images with a mismatched build-id: */ if (dso->has_build_id) { u8 build_id[BUILD_ID_SIZE]; if (elf_read_build_id(elf, build_id, BUILD_ID_SIZE) < 0) goto out_elf_end; if (!dso__build_id_equal(dso, build_id)) goto out_elf_end; } ss->symtab = elf_section_by_name(elf, &ehdr, &ss->symshdr, ".symtab", NULL); if (ss->symshdr.sh_type != SHT_SYMTAB) ss->symtab = NULL; ss->dynsym_idx = 0; ss->dynsym = elf_section_by_name(elf, &ehdr, &ss->dynshdr, ".dynsym", &ss->dynsym_idx); if (ss->dynshdr.sh_type != SHT_DYNSYM) ss->dynsym = NULL; ss->opdidx = 0; ss->opdsec = elf_section_by_name(elf, &ehdr, &ss->opdshdr, ".opd", &ss->opdidx); if (ss->opdshdr.sh_type != SHT_PROGBITS) ss->opdsec = NULL; if (dso->kernel == DSO_TYPE_USER) { GElf_Shdr shdr; ss->adjust_symbols = (ehdr.e_type == ET_EXEC || elf_section_by_name(elf, &ehdr, &shdr, ".gnu.prelink_undo", NULL) != NULL); } else { ss->adjust_symbols = 0; } ss->name = strdup(name); if (!ss->name) goto out_elf_end; ss->elf = elf; ss->fd = fd; ss->ehdr = ehdr; ss->type = type; return 0; out_elf_end: elf_end(elf); out_close: close(fd); return err; } int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *syms_ss, struct symsrc *runtime_ss, symbol_filter_t filter, int kmodule) { struct kmap *kmap = dso->kernel ? map__kmap(map) : NULL; struct map *curr_map = map; struct dso *curr_dso = dso; Elf_Data *symstrs, *secstrs; uint32_t nr_syms; int err = -1; uint32_t idx; GElf_Ehdr ehdr; GElf_Shdr shdr; Elf_Data *syms, *opddata = NULL; GElf_Sym sym; Elf_Scn *sec, *sec_strndx; Elf *elf; int nr = 0; dso->symtab_type = syms_ss->type; if (!syms_ss->symtab) { syms_ss->symtab = syms_ss->dynsym; syms_ss->symshdr = syms_ss->dynshdr; } elf = syms_ss->elf; ehdr = syms_ss->ehdr; sec = syms_ss->symtab; shdr = syms_ss->symshdr; if (runtime_ss->opdsec) opddata = elf_rawdata(runtime_ss->opdsec, NULL); syms = elf_getdata(sec, NULL); if (syms == NULL) goto out_elf_end; sec = elf_getscn(elf, shdr.sh_link); if (sec == NULL) goto out_elf_end; symstrs = elf_getdata(sec, NULL); if (symstrs == NULL) goto out_elf_end; sec_strndx = elf_getscn(elf, ehdr.e_shstrndx); if (sec_strndx == NULL) goto out_elf_end; secstrs = elf_getdata(sec_strndx, NULL); if (secstrs == NULL) goto out_elf_end; nr_syms = shdr.sh_size / shdr.sh_entsize; memset(&sym, 0, sizeof(sym)); dso->adjust_symbols = runtime_ss->adjust_symbols; elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) { struct symbol *f; const char *elf_name = elf_sym__name(&sym, symstrs); char *demangled = NULL; int is_label = elf_sym__is_label(&sym); const char *section_name; bool used_opd = false; if (kmap && kmap->ref_reloc_sym && kmap->ref_reloc_sym->name && strcmp(elf_name, kmap->ref_reloc_sym->name) == 0) kmap->ref_reloc_sym->unrelocated_addr = sym.st_value; if (!is_label && !elf_sym__is_a(&sym, map->type)) continue; /* Reject ARM ELF "mapping symbols": these aren't unique and * don't identify functions, so will confuse the profile * output: */ if (ehdr.e_machine == EM_ARM) { if (!strcmp(elf_name, "$a") || !strcmp(elf_name, "$d") || !strcmp(elf_name, "$t")) continue; } if (runtime_ss->opdsec && sym.st_shndx == runtime_ss->opdidx) { u32 offset = sym.st_value - syms_ss->opdshdr.sh_addr; u64 *opd = opddata->d_buf + offset; sym.st_value = DSO__SWAP(dso, u64, *opd); sym.st_shndx = elf_addr_to_index(runtime_ss->elf, sym.st_value); used_opd = true; } sec = elf_getscn(runtime_ss->elf, sym.st_shndx); if (!sec) goto out_elf_end; gelf_getshdr(sec, &shdr); if (is_label && !elf_sec__is_a(&shdr, secstrs, map->type)) continue; section_name = elf_sec__name(&shdr, secstrs); /* On ARM, symbols for thumb functions have 1 added to * the symbol address as a flag - remove it */ if ((ehdr.e_machine == EM_ARM) && (map->type == MAP__FUNCTION) && (sym.st_value & 1)) --sym.st_value; if (dso->kernel != DSO_TYPE_USER || kmodule) { char dso_name[PATH_MAX]; if (strcmp(section_name, (curr_dso->short_name + dso->short_name_len)) == 0) goto new_symbol; if (strcmp(section_name, ".text") == 0) { curr_map = map; curr_dso = dso; goto new_symbol; } snprintf(dso_name, sizeof(dso_name), "%s%s", dso->short_name, section_name); curr_map = map_groups__find_by_name(kmap->kmaps, map->type, dso_name); if (curr_map == NULL) { u64 start = sym.st_value; if (kmodule) start += map->start + shdr.sh_offset; curr_dso = dso__new(dso_name); if (curr_dso == NULL) goto out_elf_end; curr_dso->kernel = dso->kernel; curr_dso->long_name = dso->long_name; curr_dso->long_name_len = dso->long_name_len; curr_map = map__new2(start, curr_dso, map->type); if (curr_map == NULL) { dso__delete(curr_dso); goto out_elf_end; } curr_map->map_ip = identity__map_ip; curr_map->unmap_ip = identity__map_ip; curr_dso->symtab_type = dso->symtab_type; map_groups__insert(kmap->kmaps, curr_map); dsos__add(&dso->node, curr_dso); dso__set_loaded(curr_dso, map->type); } else curr_dso = curr_map->dso; goto new_symbol; } if ((used_opd && runtime_ss->adjust_symbols) || (!used_opd && syms_ss->adjust_symbols)) { pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " " "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__, (u64)sym.st_value, (u64)shdr.sh_addr, (u64)shdr.sh_offset); sym.st_value -= shdr.sh_addr - shdr.sh_offset; } /* * We need to figure out if the object was created from C++ sources * DWARF DW_compile_unit has this, but we don't always have access * to it... */ demangled = bfd_demangle(NULL, elf_name, DMGL_PARAMS | DMGL_ANSI); if (demangled != NULL) elf_name = demangled; new_symbol: f = symbol__new(sym.st_value, sym.st_size, GELF_ST_BIND(sym.st_info), elf_name); free(demangled); if (!f) goto out_elf_end; if (filter && filter(curr_map, f)) symbol__delete(f); else { symbols__insert(&curr_dso->symbols[curr_map->type], f); nr++; } } /* * For misannotated, zeroed, ASM function sizes. */ if (nr > 0) { symbols__fixup_duplicate(&dso->symbols[map->type]); symbols__fixup_end(&dso->symbols[map->type]); if (kmap) { /* * We need to fixup this here too because we create new * maps here, for things like vsyscall sections. */ __map_groups__fixup_end(kmap->kmaps, map->type); } } err = nr; out_elf_end: return err; } void symbol__elf_init(void) { elf_version(EV_CURRENT); }