lib/so-info.c

   1 /*
   2  * so-info.c
   3  *
   4  * Babeltrace - Executable and Shared Object Debug Info Reader
   5  *
   6  * Copyright 2015 Antoine Busque <abusque@efficios.com>
   7  *
   8  * Author: Antoine Busque <abusque@efficios.com>
   9  *
  10  * Permission is hereby granted, free of charge, to any person obtaining a copy
  11  * of this software and associated documentation files (the "Software"), to deal
  12  * in the Software without restriction, including without limitation the rights
  13  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14  * copies of the Software, and to permit persons to whom the Software is
  15  * furnished to do so, subject to the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be included in
  18  * all copies or substantial portions of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  23  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  25  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  26  * SOFTWARE.
  27  */
  28
  29 #include <fcntl.h>
  30 #include <math.h>
  31 #include <libgen.h>
  32 #include <stdio.h>
  33 #include <inttypes.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include <unistd.h>
  37 #include <dwarf.h>
  38 #include <glib.h>
  39 #include <babeltrace/dwarf.h>
  40 #include <babeltrace/so-info.h>
  41 #include <babeltrace/crc32.h>
  42 #include <babeltrace/babeltrace-internal.h>
  43 #include <babeltrace/utils.h>
  44
  45 /*
  46  * An address printed in hex is at most 20 bytes (16 for 64-bits +
  47  * leading 0x + optional leading '+' if addr is an offset + null
  48  * character).
  49  */
  50 #define ADDR_STR_LEN 20
  51
  52 BT_HIDDEN
  53 int so_info_init(void)
  54 {
  55         int ret = 0;
  56
  57         if (elf_version(EV_CURRENT) == EV_NONE) {
  58                 fprintf(stderr, "ELF library initialization failed: %s\n",
  59                         elf_errmsg(-1));
  60                 ret = -1;
  61         }
  62
  63         return ret;
  64 }
  65
  66 BT_HIDDEN
  67 struct so_info *so_info_create(const char *path, uint64_t low_addr,
  68                 uint64_t memsz, bool is_pic)
  69 {
  70         struct so_info *so = NULL;
  71
  72         if (!path) {
  73                 goto error;
  74         }
  75
  76         so = g_new0(struct so_info, 1);
  77         if (!so) {
  78                 goto error;
  79         }
  80
  81         if (opt_debug_info_target_prefix) {
  82                 so->elf_path = g_build_path("/", opt_debug_info_target_prefix,
  83                                                 path, NULL);
  84         } else {
  85                 so->elf_path = strdup(path);
  86         }
  87
  88         if (!so->elf_path) {
  89                 goto error;
  90         }
  91
  92         so->is_pic = is_pic;
  93         so->memsz = memsz;
  94         so->low_addr = low_addr;
  95         so->high_addr = so->low_addr + so->memsz;
  96
  97         return so;
  98
  99 error:
 100         so_info_destroy(so);
 101         return NULL;
 102 }
 103
 104 BT_HIDDEN
 105 void so_info_destroy(struct so_info *so)
 106 {
 107         if (!so) {
 108                 return;
 109         }
 110
 111         dwarf_end(so->dwarf_info);
 112
 113         free(so->elf_path);
 114         free(so->dwarf_path);
 115         free(so->build_id);
 116         free(so->dbg_link_filename);
 117
 118         elf_end(so->elf_file);
 119
 120         close(so->elf_fd);
 121         close(so->dwarf_fd);
 122
 123         g_free(so);
 124 }
 125
 126
 127 BT_HIDDEN
 128 int so_info_set_build_id(struct so_info *so, uint8_t *build_id,
 129                 size_t build_id_len)
 130 {
 131         if (!so || !build_id) {
 132                 goto error;
 133         }
 134
 135         so->build_id = malloc(build_id_len);
 136         if (!so->build_id) {
 137                 goto error;
 138         }
 139
 140         memcpy(so->build_id, build_id, build_id_len);
 141         so->build_id_len = build_id_len;
 142
 143         /*
 144          * Reset the is_elf_only flag in case it had been set
 145          * previously, because we might find separate debug info using
 146          * the new build id information.
 147          */
 148         so->is_elf_only = false;
 149
 150         return 0;
 151
 152 error:
 153
 154         return -1;
 155 }
 156
 157 BT_HIDDEN
 158 int so_info_set_debug_link(struct so_info *so, char *filename, uint32_t crc)
 159 {
 160         if (!so || !filename) {
 161                 goto error;
 162         }
 163
 164         so->dbg_link_filename = strdup(filename);
 165         if (!so->dbg_link_filename) {
 166                 goto error;
 167         }
 168
 169         so->dbg_link_crc = crc;
 170
 171         /*
 172          * Reset the is_elf_only flag in case it had been set
 173          * previously, because we might find separate debug info using
 174          * the new build id information.
 175          */
 176         so->is_elf_only = false;
 177
 178         return 0;
 179
 180 error:
 181
 182         return -1;
 183 }
 184
 185 /**
 186  * Tries to read DWARF info from the location given by path, and
 187  * attach it to the given so_info instance if it exists.
 188  *
 189  * @param so    so_info instance for which to set DWARF info
 190  * @param path  Presumed location of the DWARF info
 191  * @returns     0 on success, -1 on failure
 192  */
 193 static
 194 int so_info_set_dwarf_info_from_path(struct so_info *so, char *path)
 195 {
 196         int fd = -1, ret = 0;
 197         struct bt_dwarf_cu *cu = NULL;
 198         Dwarf *dwarf_info = NULL;
 199
 200         if (!so || !path) {
 201                 goto error;
 202         }
 203
 204         fd = open(path, O_RDONLY);
 205         if (fd < 0) {
 206                 goto error;
 207         }
 208
 209         dwarf_info = dwarf_begin(fd, DWARF_C_READ);
 210         if (!dwarf_info) {
 211                 goto error;
 212         }
 213
 214         /*
 215          * Check if the dwarf info has any CU. If not, the SO's object
 216          * file contains no DWARF info.
 217          */
 218         cu = bt_dwarf_cu_create(dwarf_info);
 219         if (!cu) {
 220                 goto error;
 221         }
 222
 223         ret = bt_dwarf_cu_next(cu);
 224         if (ret) {
 225                 goto error;
 226         }
 227
 228         so->dwarf_fd = fd;
 229         so->dwarf_path = strdup(path);
 230         if (!so->dwarf_path) {
 231                 goto error;
 232         }
 233         so->dwarf_info = dwarf_info;
 234         free(cu);
 235
 236         return 0;
 237
 238 error:
 239         close(fd);
 240         dwarf_end(dwarf_info);
 241         g_free(dwarf_info);
 242         free(cu);
 243
 244         return -1;
 245 }
 246
 247 /**
 248  * Try to set the dwarf_info for a given so_info instance via the
 249  * build ID method.
 250  *
 251  * @param so            so_info instance for which to retrieve the
 252  *                      DWARF info via build ID
 253  * @returns             0 on success (i.e. dwarf_info set), -1 on failure
 254  */
 255 static
 256 int so_info_set_dwarf_info_build_id(struct so_info *so)
 257 {
 258         int i = 0, ret = 0, dbg_dir_trailing_slash = 0;
 259         char *path = NULL, *build_id_file = NULL;
 260         const char *dbg_dir = NULL;
 261         size_t build_id_file_len, path_len;
 262
 263         if (!so || !so->build_id) {
 264                 goto error;
 265         }
 266
 267         dbg_dir = opt_debug_info_dir ? : DEFAULT_DEBUG_DIR;
 268
 269         dbg_dir_trailing_slash = dbg_dir[strlen(dbg_dir) - 1] == '/';
 270
 271         /* 2 characters per byte printed in hex, +2 for '/' and '\0' */
 272         build_id_file_len = (2 * so->build_id_len) + 2;
 273         build_id_file = malloc(build_id_file_len);
 274         if (!build_id_file) {
 275                 goto error;
 276         }
 277
 278         snprintf(build_id_file, 4, "%02x/", so->build_id[0]);
 279         for (i = 1; i < so->build_id_len; ++i) {
 280                 int path_idx = 3 + 2 * (i - 1);
 281
 282                 snprintf(&build_id_file[path_idx], 3, "%02x", so->build_id[i]);
 283         }
 284
 285         path_len = strlen(dbg_dir) + strlen(BUILD_ID_SUBDIR) +
 286                         strlen(build_id_file) + strlen(BUILD_ID_SUFFIX) + 1;
 287         if (!dbg_dir_trailing_slash) {
 288                 path_len += 1;
 289         }
 290
 291         path = malloc(path_len);
 292         if (!path) {
 293                 goto error;
 294         }
 295
 296         strcpy(path, dbg_dir);
 297         if (!dbg_dir_trailing_slash) {
 298                 strcat(path, "/");
 299         }
 300         strcat(path, BUILD_ID_SUBDIR);
 301         strcat(path, build_id_file);
 302         strcat(path, BUILD_ID_SUFFIX);
 303
 304         ret = so_info_set_dwarf_info_from_path(so, path);
 305         if (ret) {
 306                 goto error;
 307         }
 308
 309         goto end;
 310
 311 error:
 312         ret = -1;
 313 end:
 314         free(build_id_file);
 315         free(path);
 316
 317         return ret;
 318 }
 319
 320 /**
 321  * Tests whether the file located at path exists and has the expected
 322  * checksum.
 323  *
 324  * This predicate is used when looking up separate debug info via the
 325  * GNU debuglink method. The expected crc can be found .gnu_debuglink
 326  * section in the original ELF file, along with the filename for the
 327  * file containing the debug info.
 328  *
 329  * @param path  Full path at which to look for the debug file
 330  * @param crc   Expected checksum for the debug file
 331  * @returns     1 if the file exists and has the correct checksum,
 332  *              0 otherwise
 333  */
 334 static
 335 int is_valid_debug_file(char *path, uint32_t crc)
 336 {
 337         int ret = 0, fd = -1;
 338         uint32_t _crc = 0;
 339
 340         if (!path) {
 341                 goto end;
 342         }
 343
 344         fd = open(path, O_RDONLY);
 345         if (fd < 0) {
 346                 goto end;
 347         }
 348
 349         ret = crc32(fd, &_crc);
 350         if (ret) {
 351                 ret = 0;
 352                 goto end;
 353         }
 354
 355         ret = (crc == _crc);
 356
 357 end:
 358         close(fd);
 359         return ret;
 360 }
 361
 362 /**
 363  * Try to set the dwarf_info for a given so_info instance via the
 364  * build ID method.
 365  *
 366  * @param so            so_info instance for which to retrieve the
 367  *                      DWARF info via debug link
 368  * @returns             0 on success (i.e. dwarf_info set), -1 on failure
 369  */
 370 static
 371 int so_info_set_dwarf_info_debug_link(struct so_info *so)
 372 {
 373         int ret = 0;
 374         const char *dbg_dir = NULL;
 375         char *dir_name = NULL, *so_dir = NULL, *path = NULL;
 376         size_t max_path_len = 0;
 377
 378         if (!so || !so->dbg_link_filename) {
 379                 goto error;
 380         }
 381
 382         dbg_dir = opt_debug_info_dir ? : DEFAULT_DEBUG_DIR;
 383
 384         dir_name = dirname(so->elf_path);
 385         if (!dir_name) {
 386                 goto error;
 387         }
 388
 389         /* so_dir is just dir_name with a trailing slash */
 390         so_dir = malloc(strlen(dir_name) + 2);
 391         if (!so_dir) {
 392                 goto error;
 393         }
 394
 395         strcpy(so_dir, dir_name);
 396         strcat(so_dir, "/");
 397
 398         max_path_len = strlen(dbg_dir) + strlen(so_dir) +
 399                         strlen(DEBUG_SUBDIR) + strlen(so->dbg_link_filename)
 400                         + 1;
 401         path = malloc(max_path_len);
 402         if (!path) {
 403                 goto error;
 404         }
 405
 406         /* First look in the SO's dir */
 407         strcpy(path, so_dir);
 408         strcat(path, so->dbg_link_filename);
 409
 410         if (is_valid_debug_file(path, so->dbg_link_crc)) {
 411                 goto found;
 412         }
 413
 414         /* If not found, look in .debug subdir */
 415         strcpy(path, so_dir);
 416         strcat(path, DEBUG_SUBDIR);
 417         strcat(path, so->dbg_link_filename);
 418
 419         if (is_valid_debug_file(path, so->dbg_link_crc)) {
 420                 goto found;
 421         }
 422
 423         /* Lastly, look under the global debug directory */
 424         strcpy(path, dbg_dir);
 425         strcat(path, so_dir);
 426         strcat(path, so->dbg_link_filename);
 427
 428         if (is_valid_debug_file(path, so->dbg_link_crc)) {
 429                 goto found;
 430         }
 431
 432 error:
 433         ret = -1;
 434 end:
 435         free(path);
 436         free(so_dir);
 437
 438         return ret;
 439
 440 found:
 441         ret = so_info_set_dwarf_info_from_path(so, path);
 442         if (ret) {
 443                 goto error;
 444         }
 445
 446         goto end;
 447 }
 448
 449 /**
 450  * Initialize the DWARF info for a given executable.
 451  *
 452  * @param so    so_info instance
 453  * @returns     0 on success, -1 on failure
 454  */
 455 static
 456 int so_info_set_dwarf_info(struct so_info *so)
 457 {
 458         int ret = 0;
 459
 460         if (!so) {
 461                 goto error;
 462         }
 463
 464         /* First try to set the DWARF info from the ELF file */
 465         ret = so_info_set_dwarf_info_from_path(so, so->elf_path);
 466         if (!ret) {
 467                 goto end;
 468         }
 469
 470         /*
 471          * If that fails, try to find separate debug info via build ID
 472          * and debug link.
 473          */
 474         ret = so_info_set_dwarf_info_build_id(so);
 475         if (!ret) {
 476                 goto end;
 477         }
 478
 479         ret = so_info_set_dwarf_info_debug_link(so);
 480         if (!ret) {
 481                 goto end;
 482         }
 483
 484 error:
 485         ret = -1;
 486 end:
 487         return ret;
 488 }
 489
 490 /**
 491  * Initialize the ELF file for a given executable.
 492  *
 493  * @param so    so_info instance
 494  * @returns     0 on success, -1 on failure
 495  */
 496 static
 497 int so_info_set_elf_file(struct so_info *so)
 498 {
 499         int elf_fd;
 500         Elf *elf_file = NULL;
 501
 502         if (!so) {
 503                 goto error;
 504         }
 505
 506         elf_fd = open(so->elf_path, O_RDONLY);
 507         if (elf_fd < 0) {
 508                 fprintf(stderr, "Failed to open %s\n", so->elf_path);
 509                 goto error;
 510         }
 511
 512         elf_file = elf_begin(elf_fd, ELF_C_READ, NULL);
 513         if (!elf_file) {
 514                 fprintf(stderr, "elf_begin failed: %s\n", elf_errmsg(-1));
 515                 goto error;
 516         }
 517
 518         if (elf_kind(elf_file) != ELF_K_ELF) {
 519                 fprintf(stderr, "Error: %s is not an ELF object\n",
 520                                 so->elf_path);
 521                 goto error;
 522         }
 523
 524         so->elf_fd = elf_fd;
 525         so->elf_file = elf_file;
 526         return 0;
 527
 528 error:
 529         close(elf_fd);
 530         elf_end(elf_file);
 531         return -1;
 532 }
 533
 534
 535 BT_HIDDEN
 536 void source_location_destroy(struct source_location *src_loc)
 537 {
 538         if (!src_loc) {
 539                 return;
 540         }
 541
 542         free(src_loc->filename);
 543         g_free(src_loc);
 544 }
 545 /**
 546  * Append a string representation of an address offset to an existing
 547  * string.
 548  *
 549  * On success, the out parameter `result` will contain the base string
 550  * followed by the offset string of the form "+0x1234". On failure,
 551  * `result` remains unchanged.
 552  *
 553  * @param base_str      The string to which to append an offset string
 554  * @param low_addr      The lower virtual memory address, the base from
 555  *                      which the offset is computed
 556  * @param high_addr     The higher virtual memory address
 557  * @param result        Out parameter, the base string followed by the
 558  *                      offset string
 559  * @returns             0 on success, -1 on failure
 560  */
 561 static
 562 int so_info_append_offset_str(const char *base_str, uint64_t low_addr,
 563                                 uint64_t high_addr, char **result)
 564 {
 565         int ret;
 566         uint64_t offset;
 567         char *_result = NULL;
 568         char offset_str[ADDR_STR_LEN];
 569
 570         if (!base_str || !result) {
 571                 goto error;
 572         }
 573
 574         offset = high_addr - low_addr;
 575
 576         _result = malloc(strlen(base_str) + ADDR_STR_LEN);
 577         if (!_result) {
 578                 goto error;
 579         }
 580
 581         ret = snprintf(offset_str, ADDR_STR_LEN, "+%#0" PRIx64, offset);
 582         if (ret < 0) {
 583                 goto error;
 584         }
 585         strcpy(_result, base_str);
 586         strcat(_result, offset_str);
 587         *result = _result;
 588
 589         return 0;
 590
 591 error:
 592         free(_result);
 593         return -1;
 594 }
 595
 596 /**
 597  * Try to find the symbol closest to an address within a given ELF
 598  * section.
 599  *
 600  * Only function symbols are taken into account. The symbol's address
 601  * must precede `addr`. A symbol with a closer address might exist
 602  * after `addr` but is irrelevant because it cannot encompass `addr`.
 603  *
 604  * On success, if found, the out parameters `sym` and `shdr` are
 605  * set. On failure or if none are found, they remain unchanged.
 606  *
 607  * @param scn           ELF section in which to look for the address
 608  * @param addr          Virtual memory address for which to find the
 609  *                      nearest function symbol
 610  * @param sym           Out parameter, the nearest function symbol
 611  * @param shdr          Out parameter, the section header for scn
 612  * @returns             0 on success, -1 on failure
 613  */
 614 static
 615 int so_info_get_nearest_symbol_from_section(Elf_Scn *scn, uint64_t addr,
 616                 GElf_Sym **sym, GElf_Shdr **shdr)
 617 {
 618         int i;
 619         size_t symbol_count;
 620         Elf_Data *data = NULL;
 621         GElf_Shdr *_shdr = NULL;
 622         GElf_Sym *nearest_sym = NULL;
 623
 624         if (!scn || !sym || !shdr) {
 625                 goto error;
 626         }
 627
 628         _shdr = g_new0(GElf_Shdr, 1);
 629         if (!_shdr) {
 630                 goto error;
 631         }
 632
 633         _shdr = gelf_getshdr(scn, _shdr);
 634         if (!_shdr) {
 635                 goto error;
 636         }
 637
 638         if (_shdr->sh_type != SHT_SYMTAB) {
 639                 /*
 640                  * We are only interested in symbol table (symtab)
 641                  * sections, skip this one.
 642                  */
 643                 goto end;
 644         }
 645
 646         data = elf_getdata(scn, NULL);
 647         if (!data) {
 648                 goto error;
 649         }
 650
 651         symbol_count = _shdr->sh_size / _shdr->sh_entsize;
 652
 653         for (i = 0; i < symbol_count; ++i) {
 654                 GElf_Sym *cur_sym = NULL;
 655
 656                 cur_sym = g_new0(GElf_Sym, 1);
 657                 if (!cur_sym) {
 658                         goto error;
 659                 }
 660                 cur_sym = gelf_getsym(data, i, cur_sym);
 661                 if (!cur_sym) {
 662                         goto error;
 663                 }
 664                 if (GELF_ST_TYPE(cur_sym->st_info) != STT_FUNC) {
 665                         /* We're only interested in the functions. */
 666                         g_free(cur_sym);
 667                         continue;
 668                 }
 669
 670                 if (cur_sym->st_value <= addr &&
 671                                 (!nearest_sym ||
 672                                 cur_sym->st_value > nearest_sym->st_value)) {
 673                         g_free(nearest_sym);
 674                         nearest_sym = cur_sym;
 675                 } else {
 676                         g_free(cur_sym);
 677                 }
 678         }
 679
 680 end:
 681         if (nearest_sym) {
 682                 *sym = nearest_sym;
 683                 *shdr = _shdr;
 684         } else {
 685                 g_free(_shdr);
 686         }
 687
 688         return 0;
 689
 690 error:
 691         g_free(nearest_sym);
 692         g_free(_shdr);
 693         return -1;
 694 }
 695
 696 /**
 697  * Get the name of the function containing a given address within an
 698  * executable using ELF symbols.
 699  *
 700  * The function name is in fact the name of the nearest ELF symbol,
 701  * followed by the offset in bytes between the address and the symbol
 702  * (in hex), separated by a '+' character.
 703  *
 704  * If found, the out parameter `func_name` is set on success. On failure,
 705  * it remains unchanged.
 706  *
 707  * @param so            so_info instance for the executable containing
 708  *                      the address
 709  * @param addr          Virtual memory address for which to find the
 710  *                      function name
 711  * @param func_name     Out parameter, the function name
 712  * @returns             0 on success, -1 on failure
 713  */
 714 static
 715 int so_info_lookup_elf_function_name(struct so_info *so, uint64_t addr,
 716                 char **func_name)
 717 {
 718         /*
 719          * TODO (possible optimisation): if an ELF has no symtab
 720          * section, it has been stripped. Therefore, it would be wise
 721          * to store a flag indicating the stripped status after the
 722          * first iteration to prevent subsequent ones.
 723          */
 724         int ret = 0;
 725         Elf_Scn *scn = NULL;
 726         GElf_Sym *sym = NULL;
 727         GElf_Shdr *shdr = NULL;
 728         char *sym_name = NULL;
 729
 730         /* Set ELF file if it hasn't been accessed yet. */
 731         if (!so->elf_file) {
 732                 ret = so_info_set_elf_file(so);
 733                 if (ret) {
 734                         /* Failed to set ELF file. */
 735                         goto error;
 736                 }
 737         }
 738
 739         scn = elf_nextscn(so->elf_file, scn);
 740         if (!scn) {
 741                 goto error;
 742         }
 743
 744         while (scn && !sym) {
 745                 ret = so_info_get_nearest_symbol_from_section(
 746                                 scn, addr, &sym, &shdr);
 747                 if (ret) {
 748                         goto error;
 749                 }
 750
 751                 scn = elf_nextscn(so->elf_file, scn);
 752         }
 753
 754         if (sym) {
 755                 sym_name = elf_strptr(so->elf_file, shdr->sh_link,
 756                                 sym->st_name);
 757                 if (!sym_name) {
 758                         goto error;
 759                 }
 760
 761                 ret = so_info_append_offset_str(sym_name, sym->st_value, addr,
 762                                                 func_name);
 763                 if (ret) {
 764                         goto error;
 765                 }
 766         }
 767
 768         g_free(shdr);
 769         g_free(sym);
 770         return 0;
 771
 772 error:
 773         g_free(shdr);
 774         g_free(sym);
 775         return -1;
 776 }
 777
 778 /**
 779  * Get the name of the function containing a given address within a
 780  * given compile unit (CU).
 781  *
 782  * If found, the out parameter `func_name` is set on success. On
 783  * failure, it remains unchanged.
 784  *
 785  * @param cu            bt_dwarf_cu instance which may contain the address
 786  * @param addr          Virtual memory address for which to find the
 787  *                      function name
 788  * @param func_name     Out parameter, the function name
 789  * @returns             0 on success, -1 on failure
 790  */
 791 static
 792 int so_info_lookup_cu_function_name(struct bt_dwarf_cu *cu, uint64_t addr,
 793                 char **func_name)
 794 {
 795         int ret = 0, found = 0;
 796         struct bt_dwarf_die *die = NULL;
 797
 798         if (!cu || !func_name) {
 799                 goto error;
 800         }
 801
 802         die = bt_dwarf_die_create(cu);
 803         if (!die) {
 804                 goto error;
 805         }
 806
 807         while (bt_dwarf_die_next(die) == 0) {
 808                 int tag;
 809
 810                 ret = bt_dwarf_die_get_tag(die, &tag);
 811                 if (ret) {
 812                         goto error;
 813                 }
 814
 815                 if (tag == DW_TAG_subprogram) {
 816                         ret = bt_dwarf_die_contains_addr(die, addr, &found);
 817                         if (ret) {
 818                                 goto error;
 819                         }
 820
 821                         if (found) {
 822                                 break;
 823                         }
 824                 }
 825         }
 826
 827         if (found) {
 828                 uint64_t low_addr = 0;
 829                 char *die_name = NULL;
 830
 831                 ret = bt_dwarf_die_get_name(die, &die_name);
 832                 if (ret) {
 833                         goto error;
 834                 }
 835
 836                 ret = dwarf_lowpc(die->dwarf_die, &low_addr);
 837                 if (ret) {
 838                         goto error;
 839                 }
 840
 841                 ret = so_info_append_offset_str(die_name, low_addr, addr,
 842                                                 func_name);
 843                 if (ret) {
 844                         goto error;
 845                 }
 846         }
 847
 848         bt_dwarf_die_destroy(die);
 849         return 0;
 850
 851 error:
 852         bt_dwarf_die_destroy(die);
 853         return -1;
 854 }
 855
 856 /**
 857  * Get the name of the function containing a given address within an
 858  * executable using DWARF debug info.
 859  *
 860  * If found, the out parameter `func_name` is set on success. On
 861  * failure, it remains unchanged.
 862  *
 863  * @param so            so_info instance for the executable containing
 864  *                      the address
 865  * @param addr          Virtual memory address for which to find the
 866  *                      function name
 867  * @param func_name     Out parameter, the function name
 868  * @returns             0 on success, -1 on failure
 869  */
 870 static
 871 int so_info_lookup_dwarf_function_name(struct so_info *so, uint64_t addr,
 872                 char **func_name)
 873 {
 874         int ret = 0;
 875         char *_func_name = NULL;
 876         struct bt_dwarf_cu *cu = NULL;
 877
 878         if (!so || !func_name) {
 879                 goto error;
 880         }
 881
 882         cu = bt_dwarf_cu_create(so->dwarf_info);
 883         if (!cu) {
 884                 goto error;
 885         }
 886
 887         while (bt_dwarf_cu_next(cu) == 0) {
 888                 ret = so_info_lookup_cu_function_name(cu, addr, &_func_name);
 889                 if (ret) {
 890                         goto error;
 891                 }
 892
 893                 if (_func_name) {
 894                         break;
 895                 }
 896         }
 897
 898         if (_func_name) {
 899                 *func_name = _func_name;
 900         }
 901
 902         bt_dwarf_cu_destroy(cu);
 903         return 0;
 904
 905 error:
 906         bt_dwarf_cu_destroy(cu);
 907         return -1;
 908 }
 909
 910 BT_HIDDEN
 911 int so_info_lookup_function_name(struct so_info *so, uint64_t addr,
 912                 char **func_name)
 913 {
 914         int ret = 0;
 915         char *_func_name = NULL;
 916
 917         if (!so || !func_name) {
 918                 goto error;
 919         }
 920
 921         /* Set DWARF info if it hasn't been accessed yet. */
 922         if (!so->dwarf_info && !so->is_elf_only) {
 923                 ret = so_info_set_dwarf_info(so);
 924                 if (ret) {
 925                         /* Failed to set DWARF info, fallback to ELF. */
 926                         so->is_elf_only = true;
 927                 }
 928         }
 929
 930         if (!so_info_has_address(so, addr)) {
 931                 goto error;
 932         }
 933
 934         /*
 935          * Addresses in ELF and DWARF are relative to base address for
 936          * PIC, so make the address argument relative too if needed.
 937          */
 938         if (so->is_pic) {
 939                 addr -= so->low_addr;
 940         }
 941
 942         if (so->is_elf_only) {
 943                 ret = so_info_lookup_elf_function_name(so, addr, &_func_name);
 944         } else {
 945                 ret = so_info_lookup_dwarf_function_name(so, addr, &_func_name);
 946         }
 947
 948         if (ret || !_func_name) {
 949                 goto error;
 950         }
 951
 952         *func_name = _func_name;
 953         return 0;
 954
 955 error:
 956         return -1;
 957 }
 958
 959 BT_HIDDEN
 960 int so_info_get_bin_loc(struct so_info *so, uint64_t addr, char **bin_loc)
 961 {
 962         int ret = 0;
 963         char *_bin_loc = NULL;
 964
 965         if (!so || !bin_loc) {
 966                 goto error;
 967         }
 968
 969         if (so->is_pic) {
 970                 addr -= so->low_addr;
 971                 ret = asprintf(&_bin_loc, "+%#0" PRIx64, addr);
 972         } else {
 973                 ret = asprintf(&_bin_loc, "@%#0" PRIx64, addr);
 974         }
 975
 976         if (ret == -1 || !_bin_loc) {
 977                 goto error;
 978         }
 979
 980         *bin_loc = _bin_loc;
 981         return 0;
 982
 983 error:
 984         return -1;
 985 }
 986
 987 /**
 988  * Predicate used to determine whether the children of a given DIE
 989  * contain a specific address.
 990  *
 991  * More specifically, the parameter `die` is expected to be a
 992  * subprogram (function) DIE, and this predicate tells whether any
 993  * subroutines are inlined within this function and would contain
 994  * `addr`.
 995  *
 996  * Do note that this function advances the position of `die`. If the
 997  * address is found within one of its children, `die` will be pointing
 998  * to that child upon returning from the function, allowing to extract
 999  * the information deemed necessary.
1000  *
1001  * @param die   The parent DIE in whose children the address will be
1002  *              looked for
1003  * @param addr  The address for which to look for in the DIEs
1004  * @returns     Returns 1 if the address was found, 0 if not
1005  */
1006 static
1007 int so_info_child_die_has_address(struct bt_dwarf_die *die, uint64_t addr)
1008 {
1009         int ret = 0, contains = 0;
1010
1011         if (!die) {
1012                 goto error;
1013         }
1014
1015         ret = bt_dwarf_die_child(die);
1016         if (ret) {
1017                 goto error;
1018         }
1019
1020         do {
1021                 int tag;
1022
1023                 ret = bt_dwarf_die_get_tag(die, &tag);
1024                 if (ret) {
1025                         goto error;
1026                 }
1027
1028                 if (tag == DW_TAG_inlined_subroutine) {
1029                         ret = bt_dwarf_die_contains_addr(die, addr, &contains);
1030                         if (ret) {
1031                                 goto error;
1032                         }
1033
1034                         if (contains) {
1035                                 ret = 1;
1036                                 goto end;
1037                         }
1038                 }
1039         } while (bt_dwarf_die_next(die) == 0);
1040
1041 end:
1042         return ret;
1043
1044 error:
1045         ret = 0;
1046         goto end;
1047 }
1048
1049 /**
1050  * Lookup the source location for a given address within a CU, making
1051  * the assumption that it is contained within an inline routine in a
1052  * function.
1053  *
1054  * @param cu            bt_dwarf_cu instance in which to look for the address
1055  * @param addr          The address for which to look for
1056  * @param src_loc       Out parameter, the source location (filename and
1057  *                      line number) for the address
1058  * @returns             0 on success, -1 on failure
1059  */
1060 static
1061 int so_info_lookup_cu_src_loc_inl(struct bt_dwarf_cu *cu, uint64_t addr,
1062                 struct source_location **src_loc)
1063 {
1064         int ret = 0, found = 0;
1065         struct bt_dwarf_die *die = NULL;
1066         struct source_location *_src_loc = NULL;
1067
1068         if (!cu || !src_loc) {
1069                 goto error;
1070         }
1071
1072         die = bt_dwarf_die_create(cu);
1073         if (!die) {
1074                 goto error;
1075         }
1076
1077         while (bt_dwarf_die_next(die) == 0) {
1078                 int tag;
1079
1080                 ret = bt_dwarf_die_get_tag(die, &tag);
1081                 if (ret) {
1082                         goto error;
1083                 }
1084
1085                 if (tag == DW_TAG_subprogram) {
1086                         int contains = 0;
1087
1088                         ret = bt_dwarf_die_contains_addr(die, addr, &contains);
1089                         if (ret) {
1090                                 goto error;
1091                         }
1092
1093                         if (contains) {
1094                                 /*
1095                                  * Try to find an inlined subroutine
1096                                  * child of this DIE containing addr.
1097                                  */
1098                                 found = so_info_child_die_has_address(
1099                                                 die, addr);
1100                                 goto end;
1101                         }
1102                 }
1103         }
1104
1105 end:
1106         if (found) {
1107                 char *filename = NULL;
1108                 uint64_t line_no;
1109
1110                 _src_loc = g_new0(struct source_location, 1);
1111                 if (!_src_loc) {
1112                         goto error;
1113                 }
1114
1115                 ret = bt_dwarf_die_get_call_file(die, &filename);
1116                 if (ret) {
1117                         goto error;
1118                 }
1119                 ret = bt_dwarf_die_get_call_line(die, &line_no);
1120                 if (ret) {
1121                         free(filename);
1122                         goto error;
1123                 }
1124
1125                 _src_loc->filename = filename;
1126                 _src_loc->line_no = line_no;
1127                 *src_loc = _src_loc;
1128         }
1129
1130         bt_dwarf_die_destroy(die);
1131         return 0;
1132
1133 error:
1134         source_location_destroy(_src_loc);
1135         bt_dwarf_die_destroy(die);
1136         return -1;
1137 }
1138
1139 /**
1140  * Lookup the source location for a given address within a CU,
1141  * assuming that it is contained within an inlined function.
1142  *
1143  * A source location can be found regardless of inlining status for
1144  * this method, but in the case of an inlined function, the returned
1145  * source location will point not to the callsite but rather to the
1146  * definition site of the inline function.
1147  *
1148  * @param cu            bt_dwarf_cu instance in which to look for the address
1149  * @param addr          The address for which to look for
1150  * @param src_loc       Out parameter, the source location (filename and
1151  *                      line number) for the address
1152  * @returns             0 on success, -1 on failure
1153  */
1154 static
1155 int so_info_lookup_cu_src_loc_no_inl(struct bt_dwarf_cu *cu, uint64_t addr,
1156                 struct source_location **src_loc)
1157 {
1158         struct source_location *_src_loc = NULL;
1159         struct bt_dwarf_die *die = NULL;
1160         const char *filename = NULL;
1161         Dwarf_Line *line = NULL;
1162         Dwarf_Addr line_addr;
1163         int ret, line_no;
1164
1165         if (!cu || !src_loc) {
1166                 goto error;
1167         }
1168
1169         die = bt_dwarf_die_create(cu);
1170         if (!die) {
1171                 goto error;
1172         }
1173
1174         line = dwarf_getsrc_die(die->dwarf_die, addr);
1175         if (!line) {
1176                 goto error;
1177         }
1178
1179         ret = dwarf_lineaddr(line, &line_addr);
1180         if (ret) {
1181                 goto error;
1182         }
1183
1184         filename = dwarf_linesrc(line, NULL, NULL);
1185         if (!filename) {
1186                 goto error;
1187         }
1188
1189         if (addr == line_addr) {
1190                 _src_loc = g_new0(struct source_location, 1);
1191                 if (!_src_loc) {
1192                         goto error;
1193                 }
1194
1195                 ret = dwarf_lineno(line, &line_no);
1196                 if (ret) {
1197                         goto error;
1198                 }
1199
1200                 _src_loc->line_no = line_no;
1201                 _src_loc->filename = strdup(filename);
1202         }
1203
1204         bt_dwarf_die_destroy(die);
1205
1206         if (_src_loc) {
1207                 *src_loc = _src_loc;
1208         }
1209
1210         return 0;
1211
1212 error:
1213         source_location_destroy(_src_loc);
1214         bt_dwarf_die_destroy(die);
1215         return -1;
1216 }
1217
1218 /**
1219  * Get the source location (file name and line number) for a given
1220  * address within a compile unit (CU).
1221  *
1222  * On success, the out parameter `src_loc` is set if found. On
1223  * failure, it remains unchanged.
1224  *
1225  * @param so            bt_dwarf_cu instance for the compile unit which
1226  *                      may contain the address
1227  * @param addr          Virtual memory address for which to find the
1228  *                      source location
1229  * @param src_loc       Out parameter, the source location
1230  * @returns             0 on success, -1 on failure
1231  */
1232 static
1233 int so_info_lookup_cu_src_loc(struct bt_dwarf_cu *cu, uint64_t addr,
1234                 struct source_location **src_loc)
1235 {
1236         int ret = 0;
1237         struct source_location *_src_loc = NULL;
1238
1239         if (!cu || !src_loc) {
1240                 goto error;
1241         }
1242
1243         ret = so_info_lookup_cu_src_loc_inl(cu, addr, &_src_loc);
1244         if (ret) {
1245                 goto error;
1246         }
1247
1248         if (_src_loc) {
1249                 goto end;
1250         }
1251
1252         ret = so_info_lookup_cu_src_loc_no_inl(cu, addr, &_src_loc);
1253         if (ret) {
1254                 goto error;
1255         }
1256
1257         if (_src_loc) {
1258                 goto end;
1259         }
1260
1261 end:
1262         if (_src_loc) {
1263                 *src_loc = _src_loc;
1264         }
1265
1266         return 0;
1267
1268 error:
1269         source_location_destroy(_src_loc);
1270         return -1;
1271 }
1272
1273 BT_HIDDEN
1274 int so_info_lookup_source_location(struct so_info *so, uint64_t addr,
1275                 struct source_location **src_loc)
1276 {
1277         struct bt_dwarf_cu *cu = NULL;
1278         struct source_location *_src_loc = NULL;
1279
1280         if (!so || !src_loc) {
1281                 goto error;
1282         }
1283
1284         /* Set DWARF info if it hasn't been accessed yet. */
1285         if (!so->dwarf_info && !so->is_elf_only) {
1286                 if (so_info_set_dwarf_info(so)) {
1287                         /* Failed to set DWARF info. */
1288                         so->is_elf_only = true;
1289                 }
1290         }
1291
1292         if (so->is_elf_only) {
1293                 /* We cannot lookup source location without DWARF info. */
1294                 goto error;
1295         }
1296
1297         if (!so_info_has_address(so, addr)) {
1298                 goto error;
1299         }
1300
1301         /*
1302          * Addresses in ELF and DWARF are relative to base address for
1303          * PIC, so make the address argument relative too if needed.
1304          */
1305         if (so->is_pic) {
1306                 addr -= so->low_addr;
1307         }
1308
1309         cu = bt_dwarf_cu_create(so->dwarf_info);
1310         if (!cu) {
1311                 goto error;
1312         }
1313
1314         while (bt_dwarf_cu_next(cu) == 0) {
1315                 int ret;
1316
1317                 ret = so_info_lookup_cu_src_loc(cu, addr, &_src_loc);
1318                 if (ret) {
1319                         goto error;
1320                 }
1321
1322                 if (_src_loc) {
1323                         break;
1324                 }
1325         }
1326
1327         bt_dwarf_cu_destroy(cu);
1328         if (_src_loc) {
1329                 *src_loc = _src_loc;
1330         }
1331
1332         return 0;
1333
1334 error:
1335         source_location_destroy(_src_loc);
1336         bt_dwarf_cu_destroy(cu);
1337         return -1;
1338 }