tools/perf/util/symbol-elf.c

   1 #include <fcntl.h>
   2 #include <stdio.h>
   3 #include <errno.h>
   4 #include <string.h>
   5 #include <unistd.h>
   6 #include <inttypes.h>
   7
   8 #include "symbol.h"
   9 #include "debug.h"
  10
  11 #ifndef NT_GNU_BUILD_ID
  12 #define NT_GNU_BUILD_ID 3
  13 #endif
  14
  15 /**
  16  * elf_symtab__for_each_symbol - iterate thru all the symbols
  17  *
  18  * @syms: struct elf_symtab instance to iterate
  19  * @idx: uint32_t idx
  20  * @sym: GElf_Sym iterator
  21  */
  22 #define elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) \
  23         for (idx = 0, gelf_getsym(syms, idx, &sym);\
  24              idx < nr_syms; \
  25              idx++, gelf_getsym(syms, idx, &sym))
  26
  27 static inline uint8_t elf_sym__type(const GElf_Sym *sym)
  28 {
  29         return GELF_ST_TYPE(sym->st_info);
  30 }
  31
  32 static inline int elf_sym__is_function(const GElf_Sym *sym)
  33 {
  34         return elf_sym__type(sym) == STT_FUNC &&
  35                sym->st_name != 0 &&
  36                sym->st_shndx != SHN_UNDEF;
  37 }
  38
  39 static inline bool elf_sym__is_object(const GElf_Sym *sym)
  40 {
  41         return elf_sym__type(sym) == STT_OBJECT &&
  42                 sym->st_name != 0 &&
  43                 sym->st_shndx != SHN_UNDEF;
  44 }
  45
  46 static inline int elf_sym__is_label(const GElf_Sym *sym)
  47 {
  48         return elf_sym__type(sym) == STT_NOTYPE &&
  49                 sym->st_name != 0 &&
  50                 sym->st_shndx != SHN_UNDEF &&
  51                 sym->st_shndx != SHN_ABS;
  52 }
  53
  54 static bool elf_sym__is_a(GElf_Sym *sym, enum map_type type)
  55 {
  56         switch (type) {
  57         case MAP__FUNCTION:
  58                 return elf_sym__is_function(sym);
  59         case MAP__VARIABLE:
  60                 return elf_sym__is_object(sym);
  61         default:
  62                 return false;
  63         }
  64 }
  65
  66 static inline const char *elf_sym__name(const GElf_Sym *sym,
  67                                         const Elf_Data *symstrs)
  68 {
  69         return symstrs->d_buf + sym->st_name;
  70 }
  71
  72 static inline const char *elf_sec__name(const GElf_Shdr *shdr,
  73                                         const Elf_Data *secstrs)
  74 {
  75         return secstrs->d_buf + shdr->sh_name;
  76 }
  77
  78 static inline int elf_sec__is_text(const GElf_Shdr *shdr,
  79                                         const Elf_Data *secstrs)
  80 {
  81         return strstr(elf_sec__name(shdr, secstrs), "text") != NULL;
  82 }
  83
  84 static inline bool elf_sec__is_data(const GElf_Shdr *shdr,
  85                                     const Elf_Data *secstrs)
  86 {
  87         return strstr(elf_sec__name(shdr, secstrs), "data") != NULL;
  88 }
  89
  90 static bool elf_sec__is_a(GElf_Shdr *shdr, Elf_Data *secstrs,
  91                           enum map_type type)
  92 {
  93         switch (type) {
  94         case MAP__FUNCTION:
  95                 return elf_sec__is_text(shdr, secstrs);
  96         case MAP__VARIABLE:
  97                 return elf_sec__is_data(shdr, secstrs);
  98         default:
  99                 return false;
 100         }
 101 }
 102
 103 static size_t elf_addr_to_index(Elf *elf, GElf_Addr addr)
 104 {
 105         Elf_Scn *sec = NULL;
 106         GElf_Shdr shdr;
 107         size_t cnt = 1;
 108
 109         while ((sec = elf_nextscn(elf, sec)) != NULL) {
 110                 gelf_getshdr(sec, &shdr);
 111
 112                 if ((addr >= shdr.sh_addr) &&
 113                     (addr < (shdr.sh_addr + shdr.sh_size)))
 114                         return cnt;
 115
 116                 ++cnt;
 117         }
 118
 119         return -1;
 120 }
 121
 122 static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
 123                                     GElf_Shdr *shp, const char *name,
 124                                     size_t *idx)
 125 {
 126         Elf_Scn *sec = NULL;
 127         size_t cnt = 1;
 128
 129         /* Elf is corrupted/truncated, avoid calling elf_strptr. */
 130         if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL))
 131                 return NULL;
 132
 133         while ((sec = elf_nextscn(elf, sec)) != NULL) {
 134                 char *str;
 135
 136                 gelf_getshdr(sec, shp);
 137                 str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
 138                 if (!strcmp(name, str)) {
 139                         if (idx)
 140                                 *idx = cnt;
 141                         break;
 142                 }
 143                 ++cnt;
 144         }
 145
 146         return sec;
 147 }
 148
 149 #define elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_entries) \
 150         for (idx = 0, pos = gelf_getrel(reldata, 0, &pos_mem); \
 151              idx < nr_entries; \
 152              ++idx, pos = gelf_getrel(reldata, idx, &pos_mem))
 153
 154 #define elf_section__for_each_rela(reldata, pos, pos_mem, idx, nr_entries) \
 155         for (idx = 0, pos = gelf_getrela(reldata, 0, &pos_mem); \
 156              idx < nr_entries; \
 157              ++idx, pos = gelf_getrela(reldata, idx, &pos_mem))
 158
 159 /*
 160  * We need to check if we have a .dynsym, so that we can handle the
 161  * .plt, synthesizing its symbols, that aren't on the symtabs (be it
 162  * .dynsym or .symtab).
 163  * And always look at the original dso, not at debuginfo packages, that
 164  * have the PLT data stripped out (shdr_rel_plt.sh_type == SHT_NOBITS).
 165  */
 166 int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss, struct map *map,
 167                                 symbol_filter_t filter)
 168 {
 169         uint32_t nr_rel_entries, idx;
 170         GElf_Sym sym;
 171         u64 plt_offset;
 172         GElf_Shdr shdr_plt;
 173         struct symbol *f;
 174         GElf_Shdr shdr_rel_plt, shdr_dynsym;
 175         Elf_Data *reldata, *syms, *symstrs;
 176         Elf_Scn *scn_plt_rel, *scn_symstrs, *scn_dynsym;
 177         size_t dynsym_idx;
 178         GElf_Ehdr ehdr;
 179         char sympltname[1024];
 180         Elf *elf;
 181         int nr = 0, symidx, err = 0;
 182
 183         if (!ss->dynsym)
 184                 return 0;
 185
 186         elf = ss->elf;
 187         ehdr = ss->ehdr;
 188
 189         scn_dynsym = ss->dynsym;
 190         shdr_dynsym = ss->dynshdr;
 191         dynsym_idx = ss->dynsym_idx;
 192
 193         if (scn_dynsym == NULL)
 194                 goto out_elf_end;
 195
 196         scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
 197                                           ".rela.plt", NULL);
 198         if (scn_plt_rel == NULL) {
 199                 scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
 200                                                   ".rel.plt", NULL);
 201                 if (scn_plt_rel == NULL)
 202                         goto out_elf_end;
 203         }
 204
 205         err = -1;
 206
 207         if (shdr_rel_plt.sh_link != dynsym_idx)
 208                 goto out_elf_end;
 209
 210         if (elf_section_by_name(elf, &ehdr, &shdr_plt, ".plt", NULL) == NULL)
 211                 goto out_elf_end;
 212
 213         /*
 214          * Fetch the relocation section to find the idxes to the GOT
 215          * and the symbols in the .dynsym they refer to.
 216          */
 217         reldata = elf_getdata(scn_plt_rel, NULL);
 218         if (reldata == NULL)
 219                 goto out_elf_end;
 220
 221         syms = elf_getdata(scn_dynsym, NULL);
 222         if (syms == NULL)
 223                 goto out_elf_end;
 224
 225         scn_symstrs = elf_getscn(elf, shdr_dynsym.sh_link);
 226         if (scn_symstrs == NULL)
 227                 goto out_elf_end;
 228
 229         symstrs = elf_getdata(scn_symstrs, NULL);
 230         if (symstrs == NULL)
 231                 goto out_elf_end;
 232
 233         if (symstrs->d_size == 0)
 234                 goto out_elf_end;
 235
 236         nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize;
 237         plt_offset = shdr_plt.sh_offset;
 238
 239         if (shdr_rel_plt.sh_type == SHT_RELA) {
 240                 GElf_Rela pos_mem, *pos;
 241
 242                 elf_section__for_each_rela(reldata, pos, pos_mem, idx,
 243                                            nr_rel_entries) {
 244                         symidx = GELF_R_SYM(pos->r_info);
 245                         plt_offset += shdr_plt.sh_entsize;
 246                         gelf_getsym(syms, symidx, &sym);
 247                         snprintf(sympltname, sizeof(sympltname),
 248                                  "%s@plt", elf_sym__name(&sym, symstrs));
 249
 250                         f = symbol__new(plt_offset, shdr_plt.sh_entsize,
 251                                         STB_GLOBAL, sympltname);
 252                         if (!f)
 253                                 goto out_elf_end;
 254
 255                         if (filter && filter(map, f))
 256                                 symbol__delete(f);
 257                         else {
 258                                 symbols__insert(&dso->symbols[map->type], f);
 259                                 ++nr;
 260                         }
 261                 }
 262         } else if (shdr_rel_plt.sh_type == SHT_REL) {
 263                 GElf_Rel pos_mem, *pos;
 264                 elf_section__for_each_rel(reldata, pos, pos_mem, idx,
 265                                           nr_rel_entries) {
 266                         symidx = GELF_R_SYM(pos->r_info);
 267                         plt_offset += shdr_plt.sh_entsize;
 268                         gelf_getsym(syms, symidx, &sym);
 269                         snprintf(sympltname, sizeof(sympltname),
 270                                  "%s@plt", elf_sym__name(&sym, symstrs));
 271
 272                         f = symbol__new(plt_offset, shdr_plt.sh_entsize,
 273                                         STB_GLOBAL, sympltname);
 274                         if (!f)
 275                                 goto out_elf_end;
 276
 277                         if (filter && filter(map, f))
 278                                 symbol__delete(f);
 279                         else {
 280                                 symbols__insert(&dso->symbols[map->type], f);
 281                                 ++nr;
 282                         }
 283                 }
 284         }
 285
 286         err = 0;
 287 out_elf_end:
 288         if (err == 0)
 289                 return nr;
 290         pr_debug("%s: problems reading %s PLT info.\n",
 291                  __func__, dso->long_name);
 292         return 0;
 293 }
 294
 295 /*
 296  * Align offset to 4 bytes as needed for note name and descriptor data.
 297  */
 298 #define NOTE_ALIGN(n) (((n) + 3) & -4U)
 299
 300 static int elf_read_build_id(Elf *elf, void *bf, size_t size)
 301 {
 302         int err = -1;
 303         GElf_Ehdr ehdr;
 304         GElf_Shdr shdr;
 305         Elf_Data *data;
 306         Elf_Scn *sec;
 307         Elf_Kind ek;
 308         void *ptr;
 309
 310         if (size < BUILD_ID_SIZE)
 311                 goto out;
 312
 313         ek = elf_kind(elf);
 314         if (ek != ELF_K_ELF)
 315                 goto out;
 316
 317         if (gelf_getehdr(elf, &ehdr) == NULL) {
 318                 pr_err("%s: cannot get elf header.\n", __func__);
 319                 goto out;
 320         }
 321
 322         /*
 323          * Check following sections for notes:
 324          *   '.note.gnu.build-id'
 325          *   '.notes'
 326          *   '.note' (VDSO specific)
 327          */
 328         do {
 329                 sec = elf_section_by_name(elf, &ehdr, &shdr,
 330                                           ".note.gnu.build-id", NULL);
 331                 if (sec)
 332                         break;
 333
 334                 sec = elf_section_by_name(elf, &ehdr, &shdr,
 335                                           ".notes", NULL);
 336                 if (sec)
 337                         break;
 338
 339                 sec = elf_section_by_name(elf, &ehdr, &shdr,
 340                                           ".note", NULL);
 341                 if (sec)
 342                         break;
 343
 344                 return err;
 345
 346         } while (0);
 347
 348         data = elf_getdata(sec, NULL);
 349         if (data == NULL)
 350                 goto out;
 351
 352         ptr = data->d_buf;
 353         while (ptr < (data->d_buf + data->d_size)) {
 354                 GElf_Nhdr *nhdr = ptr;
 355                 size_t namesz = NOTE_ALIGN(nhdr->n_namesz),
 356                        descsz = NOTE_ALIGN(nhdr->n_descsz);
 357                 const char *name;
 358
 359                 ptr += sizeof(*nhdr);
 360                 name = ptr;
 361                 ptr += namesz;
 362                 if (nhdr->n_type == NT_GNU_BUILD_ID &&
 363                     nhdr->n_namesz == sizeof("GNU")) {
 364                         if (memcmp(name, "GNU", sizeof("GNU")) == 0) {
 365                                 size_t sz = min(size, descsz);
 366                                 memcpy(bf, ptr, sz);
 367                                 memset(bf + sz, 0, size - sz);
 368                                 err = descsz;
 369                                 break;
 370                         }
 371                 }
 372                 ptr += descsz;
 373         }
 374
 375 out:
 376         return err;
 377 }
 378
 379 int filename__read_build_id(const char *filename, void *bf, size_t size)
 380 {
 381         int fd, err = -1;
 382         Elf *elf;
 383
 384         if (size < BUILD_ID_SIZE)
 385                 goto out;
 386
 387         fd = open(filename, O_RDONLY);
 388         if (fd < 0)
 389                 goto out;
 390
 391         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
 392         if (elf == NULL) {
 393                 pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
 394                 goto out_close;
 395         }
 396
 397         err = elf_read_build_id(elf, bf, size);
 398
 399         elf_end(elf);
 400 out_close:
 401         close(fd);
 402 out:
 403         return err;
 404 }
 405
 406 int sysfs__read_build_id(const char *filename, void *build_id, size_t size)
 407 {
 408         int fd, err = -1;
 409
 410         if (size < BUILD_ID_SIZE)
 411                 goto out;
 412
 413         fd = open(filename, O_RDONLY);
 414         if (fd < 0)
 415                 goto out;
 416
 417         while (1) {
 418                 char bf[BUFSIZ];
 419                 GElf_Nhdr nhdr;
 420                 size_t namesz, descsz;
 421
 422                 if (read(fd, &nhdr, sizeof(nhdr)) != sizeof(nhdr))
 423                         break;
 424
 425                 namesz = NOTE_ALIGN(nhdr.n_namesz);
 426                 descsz = NOTE_ALIGN(nhdr.n_descsz);
 427                 if (nhdr.n_type == NT_GNU_BUILD_ID &&
 428                     nhdr.n_namesz == sizeof("GNU")) {
 429                         if (read(fd, bf, namesz) != (ssize_t)namesz)
 430                                 break;
 431                         if (memcmp(bf, "GNU", sizeof("GNU")) == 0) {
 432                                 size_t sz = min(descsz, size);
 433                                 if (read(fd, build_id, sz) == (ssize_t)sz) {
 434                                         memset(build_id + sz, 0, size - sz);
 435                                         err = 0;
 436                                         break;
 437                                 }
 438                         } else if (read(fd, bf, descsz) != (ssize_t)descsz)
 439                                 break;
 440                 } else {
 441                         int n = namesz + descsz;
 442                         if (read(fd, bf, n) != n)
 443                                 break;
 444                 }
 445         }
 446         close(fd);
 447 out:
 448         return err;
 449 }
 450
 451 int filename__read_debuglink(const char *filename, char *debuglink,
 452                              size_t size)
 453 {
 454         int fd, err = -1;
 455         Elf *elf;
 456         GElf_Ehdr ehdr;
 457         GElf_Shdr shdr;
 458         Elf_Data *data;
 459         Elf_Scn *sec;
 460         Elf_Kind ek;
 461
 462         fd = open(filename, O_RDONLY);
 463         if (fd < 0)
 464                 goto out;
 465
 466         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
 467         if (elf == NULL) {
 468                 pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
 469                 goto out_close;
 470         }
 471
 472         ek = elf_kind(elf);
 473         if (ek != ELF_K_ELF)
 474                 goto out_close;
 475
 476         if (gelf_getehdr(elf, &ehdr) == NULL) {
 477                 pr_err("%s: cannot get elf header.\n", __func__);
 478                 goto out_close;
 479         }
 480
 481         sec = elf_section_by_name(elf, &ehdr, &shdr,
 482                                   ".gnu_debuglink", NULL);
 483         if (sec == NULL)
 484                 goto out_close;
 485
 486         data = elf_getdata(sec, NULL);
 487         if (data == NULL)
 488                 goto out_close;
 489
 490         /* the start of this section is a zero-terminated string */
 491         strncpy(debuglink, data->d_buf, size);
 492
 493         elf_end(elf);
 494
 495 out_close:
 496         close(fd);
 497 out:
 498         return err;
 499 }
 500
 501 static int dso__swap_init(struct dso *dso, unsigned char eidata)
 502 {
 503         static unsigned int const endian = 1;
 504
 505         dso->needs_swap = DSO_SWAP__NO;
 506
 507         switch (eidata) {
 508         case ELFDATA2LSB:
 509                 /* We are big endian, DSO is little endian. */
 510                 if (*(unsigned char const *)&endian != 1)
 511                         dso->needs_swap = DSO_SWAP__YES;
 512                 break;
 513
 514         case ELFDATA2MSB:
 515                 /* We are little endian, DSO is big endian. */
 516                 if (*(unsigned char const *)&endian != 0)
 517                         dso->needs_swap = DSO_SWAP__YES;
 518                 break;
 519
 520         default:
 521                 pr_err("unrecognized DSO data encoding %d\n", eidata);
 522                 return -EINVAL;
 523         }
 524
 525         return 0;
 526 }
 527
 528 bool symsrc__possibly_runtime(struct symsrc *ss)
 529 {
 530         return ss->dynsym || ss->opdsec;
 531 }
 532
 533 bool symsrc__has_symtab(struct symsrc *ss)
 534 {
 535         return ss->symtab != NULL;
 536 }
 537
 538 void symsrc__destroy(struct symsrc *ss)
 539 {
 540         free(ss->name);
 541         elf_end(ss->elf);
 542         close(ss->fd);
 543 }
 544
 545 int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
 546                  enum dso_binary_type type)
 547 {
 548         int err = -1;
 549         GElf_Ehdr ehdr;
 550         Elf *elf;
 551         int fd;
 552
 553         fd = open(name, O_RDONLY);
 554         if (fd < 0)
 555                 return -1;
 556
 557         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
 558         if (elf == NULL) {
 559                 pr_debug("%s: cannot read %s ELF file.\n", __func__, name);
 560                 goto out_close;
 561         }
 562
 563         if (gelf_getehdr(elf, &ehdr) == NULL) {
 564                 pr_debug("%s: cannot get elf header.\n", __func__);
 565                 goto out_elf_end;
 566         }
 567
 568         if (dso__swap_init(dso, ehdr.e_ident[EI_DATA]))
 569                 goto out_elf_end;
 570
 571         /* Always reject images with a mismatched build-id: */
 572         if (dso->has_build_id) {
 573                 u8 build_id[BUILD_ID_SIZE];
 574
 575                 if (elf_read_build_id(elf, build_id, BUILD_ID_SIZE) < 0)
 576                         goto out_elf_end;
 577
 578                 if (!dso__build_id_equal(dso, build_id))
 579                         goto out_elf_end;
 580         }
 581
 582         ss->symtab = elf_section_by_name(elf, &ehdr, &ss->symshdr, ".symtab",
 583                         NULL);
 584         if (ss->symshdr.sh_type != SHT_SYMTAB)
 585                 ss->symtab = NULL;
 586
 587         ss->dynsym_idx = 0;
 588         ss->dynsym = elf_section_by_name(elf, &ehdr, &ss->dynshdr, ".dynsym",
 589                         &ss->dynsym_idx);
 590         if (ss->dynshdr.sh_type != SHT_DYNSYM)
 591                 ss->dynsym = NULL;
 592
 593         ss->opdidx = 0;
 594         ss->opdsec = elf_section_by_name(elf, &ehdr, &ss->opdshdr, ".opd",
 595                         &ss->opdidx);
 596         if (ss->opdshdr.sh_type != SHT_PROGBITS)
 597                 ss->opdsec = NULL;
 598
 599         if (dso->kernel == DSO_TYPE_USER) {
 600                 GElf_Shdr shdr;
 601                 ss->adjust_symbols = (ehdr.e_type == ET_EXEC ||
 602                                 elf_section_by_name(elf, &ehdr, &shdr,
 603                                                      ".gnu.prelink_undo",
 604                                                      NULL) != NULL);
 605         } else {
 606                 ss->adjust_symbols = 0;
 607         }
 608
 609         ss->name   = strdup(name);
 610         if (!ss->name)
 611                 goto out_elf_end;
 612
 613         ss->elf    = elf;
 614         ss->fd     = fd;
 615         ss->ehdr   = ehdr;
 616         ss->type   = type;
 617
 618         return 0;
 619
 620 out_elf_end:
 621         elf_end(elf);
 622 out_close:
 623         close(fd);
 624         return err;
 625 }
 626
 627 int dso__load_sym(struct dso *dso, struct map *map,
 628                   struct symsrc *syms_ss, struct symsrc *runtime_ss,
 629                   symbol_filter_t filter, int kmodule)
 630 {
 631         struct kmap *kmap = dso->kernel ? map__kmap(map) : NULL;
 632         struct map *curr_map = map;
 633         struct dso *curr_dso = dso;
 634         Elf_Data *symstrs, *secstrs;
 635         uint32_t nr_syms;
 636         int err = -1;
 637         uint32_t idx;
 638         GElf_Ehdr ehdr;
 639         GElf_Shdr shdr;
 640         Elf_Data *syms, *opddata = NULL;
 641         GElf_Sym sym;
 642         Elf_Scn *sec, *sec_strndx;
 643         Elf *elf;
 644         int nr = 0;
 645
 646         dso->symtab_type = syms_ss->type;
 647
 648         if (!syms_ss->symtab) {
 649                 syms_ss->symtab  = syms_ss->dynsym;
 650                 syms_ss->symshdr = syms_ss->dynshdr;
 651         }
 652
 653         elf = syms_ss->elf;
 654         ehdr = syms_ss->ehdr;
 655         sec = syms_ss->symtab;
 656         shdr = syms_ss->symshdr;
 657
 658         if (runtime_ss->opdsec)
 659                 opddata = elf_rawdata(runtime_ss->opdsec, NULL);
 660
 661         syms = elf_getdata(sec, NULL);
 662         if (syms == NULL)
 663                 goto out_elf_end;
 664
 665         sec = elf_getscn(elf, shdr.sh_link);
 666         if (sec == NULL)
 667                 goto out_elf_end;
 668
 669         symstrs = elf_getdata(sec, NULL);
 670         if (symstrs == NULL)
 671                 goto out_elf_end;
 672
 673         sec_strndx = elf_getscn(elf, ehdr.e_shstrndx);
 674         if (sec_strndx == NULL)
 675                 goto out_elf_end;
 676
 677         secstrs = elf_getdata(sec_strndx, NULL);
 678         if (secstrs == NULL)
 679                 goto out_elf_end;
 680
 681         nr_syms = shdr.sh_size / shdr.sh_entsize;
 682
 683         memset(&sym, 0, sizeof(sym));
 684         dso->adjust_symbols = runtime_ss->adjust_symbols;
 685         elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
 686                 struct symbol *f;
 687                 const char *elf_name = elf_sym__name(&sym, symstrs);
 688                 char *demangled = NULL;
 689                 int is_label = elf_sym__is_label(&sym);
 690                 const char *section_name;
 691                 bool used_opd = false;
 692
 693                 if (kmap && kmap->ref_reloc_sym && kmap->ref_reloc_sym->name &&
 694                     strcmp(elf_name, kmap->ref_reloc_sym->name) == 0)
 695                         kmap->ref_reloc_sym->unrelocated_addr = sym.st_value;
 696
 697                 if (!is_label && !elf_sym__is_a(&sym, map->type))
 698                         continue;
 699
 700                 /* Reject ARM ELF "mapping symbols": these aren't unique and
 701                  * don't identify functions, so will confuse the profile
 702                  * output: */
 703                 if (ehdr.e_machine == EM_ARM) {
 704                         if (!strcmp(elf_name, "$a") ||
 705                             !strcmp(elf_name, "$d") ||
 706                             !strcmp(elf_name, "$t"))
 707                                 continue;
 708                 }
 709
 710                 if (runtime_ss->opdsec && sym.st_shndx == runtime_ss->opdidx) {
 711                         u32 offset = sym.st_value - syms_ss->opdshdr.sh_addr;
 712                         u64 *opd = opddata->d_buf + offset;
 713                         sym.st_value = DSO__SWAP(dso, u64, *opd);
 714                         sym.st_shndx = elf_addr_to_index(runtime_ss->elf,
 715                                         sym.st_value);
 716                         used_opd = true;
 717                 }
 718                 /*
 719                  * When loading symbols in a data mapping, ABS symbols (which
 720                  * has a value of SHN_ABS in its st_shndx) failed at
 721                  * elf_getscn().  And it marks the loading as a failure so
 722                  * already loaded symbols cannot be fixed up.
 723                  *
 724                  * I'm not sure what should be done. Just ignore them for now.
 725                  * - Namhyung Kim
 726                  */
 727                 if (sym.st_shndx == SHN_ABS)
 728                         continue;
 729
 730                 sec = elf_getscn(runtime_ss->elf, sym.st_shndx);
 731                 if (!sec)
 732                         goto out_elf_end;
 733
 734                 gelf_getshdr(sec, &shdr);
 735
 736                 if (is_label && !elf_sec__is_a(&shdr, secstrs, map->type))
 737                         continue;
 738
 739                 section_name = elf_sec__name(&shdr, secstrs);
 740
 741                 /* On ARM, symbols for thumb functions have 1 added to
 742                  * the symbol address as a flag - remove it */
 743                 if ((ehdr.e_machine == EM_ARM) &&
 744                     (map->type == MAP__FUNCTION) &&
 745                     (sym.st_value & 1))
 746                         --sym.st_value;
 747
 748                 if (dso->kernel != DSO_TYPE_USER || kmodule) {
 749                         char dso_name[PATH_MAX];
 750
 751                         if (strcmp(section_name,
 752                                    (curr_dso->short_name +
 753                                     dso->short_name_len)) == 0)
 754                                 goto new_symbol;
 755
 756                         if (strcmp(section_name, ".text") == 0) {
 757                                 curr_map = map;
 758                                 curr_dso = dso;
 759                                 goto new_symbol;
 760                         }
 761
 762                         snprintf(dso_name, sizeof(dso_name),
 763                                  "%s%s", dso->short_name, section_name);
 764
 765                         curr_map = map_groups__find_by_name(kmap->kmaps, map->type, dso_name);
 766                         if (curr_map == NULL) {
 767                                 u64 start = sym.st_value;
 768
 769                                 if (kmodule)
 770                                         start += map->start + shdr.sh_offset;
 771
 772                                 curr_dso = dso__new(dso_name);
 773                                 if (curr_dso == NULL)
 774                                         goto out_elf_end;
 775                                 curr_dso->kernel = dso->kernel;
 776                                 curr_dso->long_name = dso->long_name;
 777                                 curr_dso->long_name_len = dso->long_name_len;
 778                                 curr_map = map__new2(start, curr_dso,
 779                                                      map->type);
 780                                 if (curr_map == NULL) {
 781                                         dso__delete(curr_dso);
 782                                         goto out_elf_end;
 783                                 }
 784                                 curr_map->map_ip = identity__map_ip;
 785                                 curr_map->unmap_ip = identity__map_ip;
 786                                 curr_dso->symtab_type = dso->symtab_type;
 787                                 map_groups__insert(kmap->kmaps, curr_map);
 788                                 dsos__add(&dso->node, curr_dso);
 789                                 dso__set_loaded(curr_dso, map->type);
 790                         } else
 791                                 curr_dso = curr_map->dso;
 792
 793                         goto new_symbol;
 794                 }
 795
 796                 if ((used_opd && runtime_ss->adjust_symbols)
 797                                 || (!used_opd && syms_ss->adjust_symbols)) {
 798                         pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
 799                                   "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
 800                                   (u64)sym.st_value, (u64)shdr.sh_addr,
 801                                   (u64)shdr.sh_offset);
 802                         sym.st_value -= shdr.sh_addr - shdr.sh_offset;
 803                 }
 804                 /*
 805                  * We need to figure out if the object was created from C++ sources
 806                  * DWARF DW_compile_unit has this, but we don't always have access
 807                  * to it...
 808                  */
 809                 demangled = bfd_demangle(NULL, elf_name, DMGL_PARAMS | DMGL_ANSI);
 810                 if (demangled != NULL)
 811                         elf_name = demangled;
 812 new_symbol:
 813                 f = symbol__new(sym.st_value, sym.st_size,
 814                                 GELF_ST_BIND(sym.st_info), elf_name);
 815                 free(demangled);
 816                 if (!f)
 817                         goto out_elf_end;
 818
 819                 if (filter && filter(curr_map, f))
 820                         symbol__delete(f);
 821                 else {
 822                         symbols__insert(&curr_dso->symbols[curr_map->type], f);
 823                         nr++;
 824                 }
 825         }
 826
 827         /*
 828          * For misannotated, zeroed, ASM function sizes.
 829          */
 830         if (nr > 0) {
 831                 symbols__fixup_duplicate(&dso->symbols[map->type]);
 832                 symbols__fixup_end(&dso->symbols[map->type]);
 833                 if (kmap) {
 834                         /*
 835                          * We need to fixup this here too because we create new
 836                          * maps here, for things like vsyscall sections.
 837                          */
 838                         __map_groups__fixup_end(kmap->kmaps, map->type);
 839                 }
 840         }
 841         err = nr;
 842 out_elf_end:
 843         return err;
 844 }
 845
 846 void symbol__elf_init(void)
 847 {
 848         elf_version(EV_CURRENT);
 849 }