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