3a603b8f1561f0b2c52cb8e2b5765a559b9501b3
[babeltrace.git] / 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 so->elf_path = strdup(path);
82 if (!so->elf_path) {
83 goto error;
84 }
85
86 so->is_pic = is_pic;
87 so->memsz = memsz;
88 so->low_addr = low_addr;
89 so->high_addr = so->low_addr + so->memsz;
90
91 return so;
92
93 error:
94 so_info_destroy(so);
95 return NULL;
96 }
97
98 BT_HIDDEN
99 void so_info_destroy(struct so_info *so)
100 {
101 if (!so) {
102 return;
103 }
104
105 dwarf_end(so->dwarf_info);
106
107 free(so->elf_path);
108 free(so->dwarf_path);
109 free(so->build_id);
110 free(so->dbg_link_filename);
111
112 elf_end(so->elf_file);
113
114 close(so->elf_fd);
115 close(so->dwarf_fd);
116
117 g_free(so);
118 }
119
120
121 BT_HIDDEN
122 int so_info_set_build_id(struct so_info *so, uint8_t *build_id,
123 size_t build_id_len)
124 {
125 if (!so || !build_id) {
126 goto error;
127 }
128
129 so->build_id = malloc(build_id_len);
130 if (!so->build_id) {
131 goto error;
132 }
133
134 memcpy(so->build_id, build_id, build_id_len);
135 so->build_id_len = build_id_len;
136
137 /*
138 * Reset the is_elf_only flag in case it had been set
139 * previously, because we might find separate debug info using
140 * the new build id information.
141 */
142 so->is_elf_only = false;
143
144 return 0;
145
146 error:
147
148 return -1;
149 }
150
151 BT_HIDDEN
152 int so_info_set_debug_link(struct so_info *so, char *filename, uint32_t crc)
153 {
154 if (!so || !filename) {
155 goto error;
156 }
157
158 so->dbg_link_filename = strdup(filename);
159 if (!so->dbg_link_filename) {
160 goto error;
161 }
162
163 so->dbg_link_crc = crc;
164
165 /*
166 * Reset the is_elf_only flag in case it had been set
167 * previously, because we might find separate debug info using
168 * the new build id information.
169 */
170 so->is_elf_only = false;
171
172 return 0;
173
174 error:
175
176 return -1;
177 }
178
179 /**
180 * Tries to read DWARF info from the location given by path, and
181 * attach it to the given so_info instance if it exists.
182 *
183 * @param so so_info instance for which to set DWARF info
184 * @param path Presumed location of the DWARF info
185 * @returns 0 on success, -1 on failure
186 */
187 static
188 int so_info_set_dwarf_info_from_path(struct so_info *so, char *path)
189 {
190 int fd = -1, ret = 0;
191 struct bt_dwarf_cu *cu = NULL;
192 Dwarf *dwarf_info = NULL;
193
194 if (!so || !path) {
195 goto error;
196 }
197
198 fd = open(path, O_RDONLY);
199 if (fd < 0) {
200 goto error;
201 }
202
203 dwarf_info = dwarf_begin(fd, DWARF_C_READ);
204 if (!dwarf_info) {
205 goto error;
206 }
207
208 /*
209 * Check if the dwarf info has any CU. If not, the SO's object
210 * file contains no DWARF info.
211 */
212 cu = bt_dwarf_cu_create(dwarf_info);
213 if (!cu) {
214 goto error;
215 }
216
217 ret = bt_dwarf_cu_next(cu);
218 if (ret) {
219 goto error;
220 }
221
222 so->dwarf_fd = fd;
223 so->dwarf_path = strdup(path);
224 if (!so->dwarf_path) {
225 goto error;
226 }
227 so->dwarf_info = dwarf_info;
228 free(cu);
229
230 return 0;
231
232 error:
233 close(fd);
234 dwarf_end(dwarf_info);
235 g_free(dwarf_info);
236 free(cu);
237
238 return -1;
239 }
240
241 /**
242 * Try to set the dwarf_info for a given so_info instance via the
243 * build ID method.
244 *
245 * @param so so_info instance for which to retrieve the
246 * DWARF info via build ID
247 * @returns 0 on success (i.e. dwarf_info set), -1 on failure
248 */
249 static
250 int so_info_set_dwarf_info_build_id(struct so_info *so)
251 {
252 int i = 0, ret = 0, dbg_dir_trailing_slash = 0;
253 char *path = NULL, *build_id_file = NULL;
254 const char *dbg_dir = NULL;
255 size_t build_id_file_len, path_len;
256
257 if (!so || !so->build_id) {
258 goto error;
259 }
260
261 dbg_dir = opt_debug_info_dir ? : DEFAULT_DEBUG_DIR;
262
263 dbg_dir_trailing_slash = dbg_dir[strlen(dbg_dir) - 1] == '/';
264
265 /* 2 characters per byte printed in hex, +2 for '/' and '\0' */
266 build_id_file_len = (2 * so->build_id_len) + 2;
267 build_id_file = malloc(build_id_file_len);
268 if (!build_id_file) {
269 goto error;
270 }
271
272 snprintf(build_id_file, 4, "%02x/", so->build_id[0]);
273 for (i = 1; i < so->build_id_len; ++i) {
274 int path_idx = 3 + 2 * (i - 1);
275
276 snprintf(&build_id_file[path_idx], 3, "%02x", so->build_id[i]);
277 }
278
279 path_len = strlen(dbg_dir) + strlen(BUILD_ID_SUBDIR) +
280 strlen(build_id_file) + strlen(BUILD_ID_SUFFIX) + 1;
281 if (!dbg_dir_trailing_slash) {
282 path_len += 1;
283 }
284
285 path = malloc(path_len);
286 if (!path) {
287 goto error;
288 }
289
290 strcpy(path, dbg_dir);
291 if (!dbg_dir_trailing_slash) {
292 strcat(path, "/");
293 }
294 strcat(path, BUILD_ID_SUBDIR);
295 strcat(path, build_id_file);
296 strcat(path, BUILD_ID_SUFFIX);
297
298 ret = so_info_set_dwarf_info_from_path(so, path);
299 if (ret) {
300 goto error;
301 }
302
303 goto end;
304
305 error:
306 ret = -1;
307 end:
308 free(build_id_file);
309 free(path);
310
311 return ret;
312 }
313
314 /**
315 * Tests whether the file located at path exists and has the expected
316 * checksum.
317 *
318 * This predicate is used when looking up separate debug info via the
319 * GNU debuglink method. The expected crc can be found .gnu_debuglink
320 * section in the original ELF file, along with the filename for the
321 * file containing the debug info.
322 *
323 * @param path Full path at which to look for the debug file
324 * @param crc Expected checksum for the debug file
325 * @returns 1 if the file exists and has the correct checksum,
326 * 0 otherwise
327 */
328 static
329 int is_valid_debug_file(char *path, uint32_t crc)
330 {
331 int ret = 0, fd = -1;
332 uint32_t _crc = 0;
333
334 if (!path) {
335 goto end;
336 }
337
338 fd = open(path, O_RDONLY);
339 if (fd < 0) {
340 goto end;
341 }
342
343 ret = crc32(fd, &_crc);
344 if (ret) {
345 ret = 0;
346 goto end;
347 }
348
349 ret = (crc == _crc);
350
351 end:
352 close(fd);
353 return ret;
354 }
355
356 /**
357 * Try to set the dwarf_info for a given so_info instance via the
358 * build ID method.
359 *
360 * @param so so_info instance for which to retrieve the
361 * DWARF info via debug link
362 * @returns 0 on success (i.e. dwarf_info set), -1 on failure
363 */
364 static
365 int so_info_set_dwarf_info_debug_link(struct so_info *so)
366 {
367 int ret = 0;
368 const char *dbg_dir = NULL;
369 char *dir_name = NULL, *so_dir = NULL, *path = NULL;
370 size_t max_path_len = 0;
371
372 if (!so || !so->dbg_link_filename) {
373 goto error;
374 }
375
376 dbg_dir = opt_debug_info_dir ? : DEFAULT_DEBUG_DIR;
377
378 dir_name = dirname(so->elf_path);
379 if (!dir_name) {
380 goto error;
381 }
382
383 /* so_dir is just dir_name with a trailing slash */
384 so_dir = malloc(strlen(dir_name) + 2);
385 if (!so_dir) {
386 goto error;
387 }
388
389 strcpy(so_dir, dir_name);
390 strcat(so_dir, "/");
391
392 max_path_len = strlen(dbg_dir) + strlen(so_dir) +
393 strlen(DEBUG_SUBDIR) + strlen(so->dbg_link_filename)
394 + 1;
395 path = malloc(max_path_len);
396 if (!path) {
397 goto error;
398 }
399
400 /* First look in the SO's dir */
401 strcpy(path, so_dir);
402 strcat(path, so->dbg_link_filename);
403
404 if (is_valid_debug_file(path, so->dbg_link_crc)) {
405 goto found;
406 }
407
408 /* If not found, look in .debug subdir */
409 strcpy(path, so_dir);
410 strcat(path, DEBUG_SUBDIR);
411 strcat(path, so->dbg_link_filename);
412
413 if (is_valid_debug_file(path, so->dbg_link_crc)) {
414 goto found;
415 }
416
417 /* Lastly, look under the global debug directory */
418 strcpy(path, dbg_dir);
419 strcat(path, so_dir);
420 strcat(path, so->dbg_link_filename);
421
422 if (is_valid_debug_file(path, so->dbg_link_crc)) {
423 goto found;
424 }
425
426 error:
427 ret = -1;
428 end:
429 free(path);
430 free(so_dir);
431
432 return ret;
433
434 found:
435 ret = so_info_set_dwarf_info_from_path(so, path);
436 if (ret) {
437 goto error;
438 }
439
440 goto end;
441 }
442
443 /**
444 * Initialize the DWARF info for a given executable.
445 *
446 * @param so so_info instance
447 * @returns 0 on success, -1 on failure
448 */
449 static
450 int so_info_set_dwarf_info(struct so_info *so)
451 {
452 int ret = 0;
453
454 if (!so) {
455 goto error;
456 }
457
458 /* First try to set the DWARF info from the ELF file */
459 ret = so_info_set_dwarf_info_from_path(so, so->elf_path);
460 if (!ret) {
461 goto end;
462 }
463
464 /*
465 * If that fails, try to find separate debug info via build ID
466 * and debug link.
467 */
468 ret = so_info_set_dwarf_info_build_id(so);
469 if (!ret) {
470 goto end;
471 }
472
473 ret = so_info_set_dwarf_info_debug_link(so);
474 if (!ret) {
475 goto end;
476 }
477
478 error:
479 ret = -1;
480 end:
481 return ret;
482 }
483
484 /**
485 * Initialize the ELF file for a given executable.
486 *
487 * @param so so_info instance
488 * @returns 0 on success, -1 on failure
489 */
490 static
491 int so_info_set_elf_file(struct so_info *so)
492 {
493 int elf_fd;
494 Elf *elf_file = NULL;
495
496 if (!so) {
497 goto error;
498 }
499
500 elf_fd = open(so->elf_path, O_RDONLY);
501 if (elf_fd < 0) {
502 fprintf(stderr, "Failed to open %s\n", so->elf_path);
503 goto error;
504 }
505
506 elf_file = elf_begin(elf_fd, ELF_C_READ, NULL);
507 if (!elf_file) {
508 fprintf(stderr, "elf_begin failed: %s\n", elf_errmsg(-1));
509 goto error;
510 }
511
512 if (elf_kind(elf_file) != ELF_K_ELF) {
513 fprintf(stderr, "Error: %s is not an ELF object\n",
514 so->elf_path);
515 goto error;
516 }
517
518 so->elf_fd = elf_fd;
519 so->elf_file = elf_file;
520 return 0;
521
522 error:
523 close(elf_fd);
524 elf_end(elf_file);
525 return -1;
526 }
527
528
529 BT_HIDDEN
530 void source_location_destroy(struct source_location *src_loc)
531 {
532 if (!src_loc) {
533 return;
534 }
535
536 free(src_loc->filename);
537 g_free(src_loc);
538 }
539
540 /**
541 * Try to find the symbol closest to an address within a given ELF
542 * section.
543 *
544 * Only function symbols are taken into account. The symbol's address
545 * must precede `addr`. A symbol with a closer address might exist
546 * after `addr` but is irrelevant because it cannot encompass `addr`.
547 *
548 * On success, if found, the out parameters `sym` and `shdr` are
549 * set. On failure or if none are found, they remain unchanged.
550 *
551 * @param scn ELF section in which to look for the address
552 * @param addr Virtual memory address for which to find the
553 * nearest function symbol
554 * @param sym Out parameter, the nearest function symbol
555 * @param shdr Out parameter, the section header for scn
556 * @returns 0 on success, -1 on failure
557 */
558 static
559 int so_info_get_nearest_symbol_from_section(Elf_Scn *scn, uint64_t addr,
560 GElf_Sym **sym, GElf_Shdr **shdr)
561 {
562 int i;
563 size_t symbol_count;
564 Elf_Data *data = NULL;
565 GElf_Shdr *_shdr = NULL;
566 GElf_Sym *nearest_sym = NULL;
567
568 if (!scn || !sym || !shdr) {
569 goto error;
570 }
571
572 _shdr = g_new0(GElf_Shdr, 1);
573 if (!_shdr) {
574 goto error;
575 }
576
577 _shdr = gelf_getshdr(scn, _shdr);
578 if (!_shdr) {
579 goto error;
580 }
581
582 if (_shdr->sh_type != SHT_SYMTAB) {
583 /*
584 * We are only interested in symbol table (symtab)
585 * sections, skip this one.
586 */
587 goto end;
588 }
589
590 data = elf_getdata(scn, NULL);
591 if (!data) {
592 goto error;
593 }
594
595 symbol_count = _shdr->sh_size / _shdr->sh_entsize;
596
597 for (i = 0; i < symbol_count; ++i) {
598 GElf_Sym *cur_sym = NULL;
599
600 cur_sym = g_new0(GElf_Sym, 1);
601 if (!cur_sym) {
602 goto error;
603 }
604 cur_sym = gelf_getsym(data, i, cur_sym);
605 if (!cur_sym) {
606 goto error;
607 }
608 if (GELF_ST_TYPE(cur_sym->st_info) != STT_FUNC) {
609 /* We're only interested in the functions. */
610 g_free(cur_sym);
611 continue;
612 }
613
614 if (cur_sym->st_value <= addr &&
615 (!nearest_sym ||
616 cur_sym->st_value > nearest_sym->st_value)) {
617 g_free(nearest_sym);
618 nearest_sym = cur_sym;
619 } else {
620 g_free(cur_sym);
621 }
622 }
623
624 end:
625 if (nearest_sym) {
626 *sym = nearest_sym;
627 *shdr = _shdr;
628 } else {
629 g_free(_shdr);
630 }
631
632 return 0;
633
634 error:
635 g_free(nearest_sym);
636 g_free(_shdr);
637 return -1;
638 }
639
640 /**
641 * Get the name of the function containing a given address within an
642 * executable using ELF symbols.
643 *
644 * The function name is in fact the name of the nearest ELF symbol,
645 * followed by the offset in bytes between the address and the symbol
646 * (in hex), separated by a '+' character.
647 *
648 * If found, the out parameter `func_name` is set on success. On failure,
649 * it remains unchanged.
650 *
651 * @param so so_info instance for the executable containing
652 * the address
653 * @param addr Virtual memory address for which to find the
654 * function name
655 * @param func_name Out parameter, the function name
656 * @returns 0 on success, -1 on failure
657 */
658 static
659 int so_info_lookup_elf_function_name(struct so_info *so, uint64_t addr,
660 char **func_name)
661 {
662 /*
663 * TODO (possible optimisation): if an ELF has no symtab
664 * section, it has been stripped. Therefore, it would be wise
665 * to store a flag indicating the stripped status after the
666 * first iteration to prevent subsequent ones.
667 */
668 int ret = 0;
669 Elf_Scn *scn = NULL;
670 GElf_Sym *sym = NULL;
671 GElf_Shdr *shdr = NULL;
672 char *sym_name = NULL;
673 char *_func_name = NULL;
674 char offset_str[ADDR_STR_LEN];
675
676 /* Set ELF file if it hasn't been accessed yet. */
677 if (!so->elf_file) {
678 ret = so_info_set_elf_file(so);
679 if (ret) {
680 /* Failed to set ELF file. */
681 goto error;
682 }
683 }
684
685 scn = elf_nextscn(so->elf_file, scn);
686 if (!scn) {
687 goto error;
688 }
689
690 while (scn && !sym) {
691 ret = so_info_get_nearest_symbol_from_section(
692 scn, addr, &sym, &shdr);
693 if (ret) {
694 goto error;
695 }
696
697 scn = elf_nextscn(so->elf_file, scn);
698 }
699
700 if (sym) {
701 sym_name = elf_strptr(so->elf_file, shdr->sh_link,
702 sym->st_name);
703 if (!sym_name) {
704 goto error;
705 }
706
707 snprintf(offset_str, ADDR_STR_LEN, "+%#0" PRIx64,
708 addr - sym->st_value);
709 _func_name = malloc(strlen(sym_name) + ADDR_STR_LEN);
710 if (!_func_name) {
711 goto error;
712 }
713
714 strcpy(_func_name, sym_name);
715 strcat(_func_name, offset_str);
716 *func_name = _func_name;
717 }
718
719 g_free(shdr);
720 g_free(sym);
721 return 0;
722
723 error:
724 g_free(shdr);
725 g_free(sym);
726 free(_func_name);
727 return -1;
728 }
729
730 /**
731 * Get the name of the function containing a given address within a
732 * given compile unit (CU).
733 *
734 * If found, the out parameter `func_name` is set on success. On
735 * failure, it remains unchanged.
736 *
737 * @param cu bt_dwarf_cu instance which may contain the address
738 * @param addr Virtual memory address for which to find the
739 * function name
740 * @param func_name Out parameter, the function name
741 * @returns 0 on success, -1 on failure
742 */
743 static
744 int so_info_lookup_cu_function_name(struct bt_dwarf_cu *cu, uint64_t addr,
745 char **func_name)
746 {
747 int ret = 0, found = 0;
748 char *_func_name = NULL;
749 struct bt_dwarf_die *die = NULL;
750
751 if (!cu || !func_name) {
752 goto error;
753 }
754
755 die = bt_dwarf_die_create(cu);
756 if (!die) {
757 goto error;
758 }
759
760 while (bt_dwarf_die_next(die) == 0) {
761 int tag;
762
763 ret = bt_dwarf_die_get_tag(die, &tag);
764 if (ret) {
765 goto error;
766 }
767
768 if (tag == DW_TAG_subprogram) {
769 ret = bt_dwarf_die_contains_addr(die, addr, &found);
770 if (ret) {
771 goto error;
772 }
773
774 if (found) {
775 break;
776 }
777 }
778 }
779
780 if (found) {
781 ret = bt_dwarf_die_get_name(die, &_func_name);
782 if (ret) {
783 goto error;
784 }
785
786 *func_name = _func_name;
787 }
788
789 bt_dwarf_die_destroy(die);
790 return 0;
791
792 error:
793 bt_dwarf_die_destroy(die);
794 return -1;
795 }
796
797 /**
798 * Get the name of the function containing a given address within an
799 * executable using DWARF debug info.
800 *
801 * If found, the out parameter `func_name` is set on success. On
802 * failure, it remains unchanged.
803 *
804 * @param so so_info instance for the executable containing
805 * the address
806 * @param addr Virtual memory address for which to find the
807 * function name
808 * @param func_name Out parameter, the function name
809 * @returns 0 on success, -1 on failure
810 */
811 static
812 int so_info_lookup_dwarf_function_name(struct so_info *so, uint64_t addr,
813 char **func_name)
814 {
815 int ret = 0;
816 char *_func_name = NULL;
817 struct bt_dwarf_cu *cu = NULL;
818
819 if (!so || !func_name) {
820 goto error;
821 }
822
823 cu = bt_dwarf_cu_create(so->dwarf_info);
824 if (!cu) {
825 goto error;
826 }
827
828 while (bt_dwarf_cu_next(cu) == 0) {
829 ret = so_info_lookup_cu_function_name(cu, addr, &_func_name);
830 if (ret) {
831 goto error;
832 }
833
834 if (_func_name) {
835 break;
836 }
837 }
838
839 if (_func_name) {
840 *func_name = _func_name;
841 }
842
843 bt_dwarf_cu_destroy(cu);
844 return 0;
845
846 error:
847 bt_dwarf_cu_destroy(cu);
848 return -1;
849 }
850
851 BT_HIDDEN
852 int so_info_lookup_function_name(struct so_info *so, uint64_t ip,
853 char **func_name)
854 {
855 int ret = 0;
856 char *_func_name = NULL;
857 uint64_t relative_addr;
858
859 if (!so || !func_name) {
860 goto error;
861 }
862
863 /* Set DWARF info if it hasn't been accessed yet. */
864 if (!so->dwarf_info && !so->is_elf_only) {
865 ret = so_info_set_dwarf_info(so);
866 if (ret) {
867 /* Failed to set DWARF info, fallback to ELF. */
868 so->is_elf_only = true;
869 }
870 }
871
872 if (!so_info_has_address(so, ip)) {
873 goto error;
874 }
875
876 relative_addr = ip - so->low_addr;
877 /*
878 * Addresses in ELF and DWARF are relative to base address for
879 * PIC, so make the address argument relative too if needed.
880 */
881 if (so->is_elf_only) {
882 ret = so_info_lookup_elf_function_name(so,
883 so->is_pic ? relative_addr : ip,
884 &_func_name);
885 } else {
886 ret = so_info_lookup_dwarf_function_name(so,
887 so->is_pic ? relative_addr : ip,
888 &_func_name);
889 }
890
891 if (ret) {
892 goto error;
893 }
894
895 if (!_func_name) {
896 /*
897 * Can't map to a function; fallback to a generic output of the
898 * form binary+/@address.
899 *
900 * FIXME check position independence flag.
901 */
902 const char *binary_name = get_filename_from_path(so->elf_path);
903
904 ret = asprintf(&_func_name, "%s+%#0" PRIx64, binary_name,
905 relative_addr);
906 if (!_func_name) {
907 goto error;
908 }
909 }
910
911 *func_name = _func_name;
912 return 0;
913
914 error:
915 return -1;
916 }
917
918 /**
919 * Predicate used to determine whether the children of a given DIE
920 * contain a specific address.
921 *
922 * More specifically, the parameter `die` is expected to be a
923 * subprogram (function) DIE, and this predicate tells whether any
924 * subroutines are inlined within this function and would contain
925 * `addr`.
926 *
927 * Do note that this function advances the position of `die`. If the
928 * address is found within one of its children, `die` will be pointing
929 * to that child upon returning from the function, allowing to extract
930 * the information deemed necessary.
931 *
932 * @param die The parent DIE in whose children the address will be
933 * looked for
934 * @param addr The address for which to look for in the DIEs
935 * @returns Returns 1 if the address was found, 0 if not
936 */
937 static
938 int so_info_child_die_has_address(struct bt_dwarf_die *die, uint64_t addr)
939 {
940 int ret = 0, contains = 0;
941
942 if (!die) {
943 goto error;
944 }
945
946 ret = bt_dwarf_die_child(die);
947 if (ret) {
948 goto error;
949 }
950
951 do {
952 int tag;
953
954 ret = bt_dwarf_die_get_tag(die, &tag);
955 if (ret) {
956 goto error;
957 }
958
959 if (tag == DW_TAG_inlined_subroutine) {
960 ret = bt_dwarf_die_contains_addr(die, addr, &contains);
961 if (ret) {
962 goto error;
963 }
964
965 if (contains) {
966 ret = 1;
967 goto end;
968 }
969 }
970 } while (bt_dwarf_die_next(die) == 0);
971
972 end:
973 return ret;
974
975 error:
976 ret = 0;
977 goto end;
978 }
979
980 /**
981 * Lookup the source location for a given address within a CU, making
982 * the assumption that it is contained within an inline routine in a
983 * function.
984 *
985 * @param cu bt_dwarf_cu instance in which to look for the address
986 * @param addr The address for which to look for
987 * @param src_loc Out parameter, the source location (filename and
988 * line number) for the address
989 * @returns 0 on success, -1 on failure
990 */
991 static
992 int so_info_lookup_cu_src_loc_inl(struct bt_dwarf_cu *cu, uint64_t addr,
993 struct source_location **src_loc)
994 {
995 int ret = 0, found = 0;
996 struct bt_dwarf_die *die = NULL;
997 struct source_location *_src_loc = NULL;
998
999 if (!cu || !src_loc) {
1000 goto error;
1001 }
1002
1003 die = bt_dwarf_die_create(cu);
1004 if (!die) {
1005 goto error;
1006 }
1007
1008 while (bt_dwarf_die_next(die) == 0) {
1009 int tag;
1010
1011 ret = bt_dwarf_die_get_tag(die, &tag);
1012 if (ret) {
1013 goto error;
1014 }
1015
1016 if (tag == DW_TAG_subprogram) {
1017 int contains = 0;
1018
1019 ret = bt_dwarf_die_contains_addr(die, addr, &contains);
1020 if (ret) {
1021 goto error;
1022 }
1023
1024 if (contains) {
1025 /*
1026 * Try to find an inlined subroutine
1027 * child of this DIE containing addr.
1028 */
1029 found = so_info_child_die_has_address(
1030 die, addr);
1031 goto end;
1032 }
1033 }
1034 }
1035
1036 end:
1037 if (found) {
1038 char *filename = NULL;
1039 uint64_t line_no;
1040
1041 _src_loc = g_new0(struct source_location, 1);
1042 if (!_src_loc) {
1043 goto error;
1044 }
1045
1046 ret = bt_dwarf_die_get_call_file(die, &filename);
1047 if (ret) {
1048 goto error;
1049 }
1050 ret = bt_dwarf_die_get_call_line(die, &line_no);
1051 if (ret) {
1052 free(filename);
1053 goto error;
1054 }
1055
1056 _src_loc->filename = filename;
1057 _src_loc->line_no = line_no;
1058 *src_loc = _src_loc;
1059 }
1060
1061 bt_dwarf_die_destroy(die);
1062 return 0;
1063
1064 error:
1065 source_location_destroy(_src_loc);
1066 bt_dwarf_die_destroy(die);
1067 return -1;
1068 }
1069
1070 /**
1071 * Lookup the source location for a given address within a CU,
1072 * assuming that it is contained within an inlined function.
1073 *
1074 * A source location can be found regardless of inlining status for
1075 * this method, but in the case of an inlined function, the returned
1076 * source location will point not to the callsite but rather to the
1077 * definition site of the inline function.
1078 *
1079 * @param cu bt_dwarf_cu instance in which to look for the address
1080 * @param addr The address for which to look for
1081 * @param src_loc Out parameter, the source location (filename and
1082 * line number) for the address
1083 * @returns 0 on success, -1 on failure
1084 */
1085 static
1086 int so_info_lookup_cu_src_loc_no_inl(struct bt_dwarf_cu *cu, uint64_t addr,
1087 struct source_location **src_loc)
1088 {
1089 struct source_location *_src_loc = NULL;
1090 struct bt_dwarf_die *die = NULL;
1091 const char *filename = NULL;
1092 Dwarf_Line *line = NULL;
1093 Dwarf_Addr line_addr;
1094 int ret, line_no;
1095
1096 if (!cu || !src_loc) {
1097 goto error;
1098 }
1099
1100 die = bt_dwarf_die_create(cu);
1101 if (!die) {
1102 goto error;
1103 }
1104
1105 line = dwarf_getsrc_die(die->dwarf_die, addr);
1106 if (!line) {
1107 goto error;
1108 }
1109
1110 ret = dwarf_lineaddr(line, &line_addr);
1111 if (ret) {
1112 goto error;
1113 }
1114
1115 filename = dwarf_linesrc(line, NULL, NULL);
1116 if (!filename) {
1117 goto error;
1118 }
1119
1120 if (addr == line_addr) {
1121 _src_loc = g_new0(struct source_location, 1);
1122 if (!_src_loc) {
1123 goto error;
1124 }
1125
1126 ret = dwarf_lineno(line, &line_no);
1127 if (ret) {
1128 goto error;
1129 }
1130
1131 _src_loc->line_no = line_no;
1132 _src_loc->filename = strdup(filename);
1133 }
1134
1135 bt_dwarf_die_destroy(die);
1136
1137 if (_src_loc) {
1138 *src_loc = _src_loc;
1139 }
1140
1141 return 0;
1142
1143 error:
1144 source_location_destroy(_src_loc);
1145 bt_dwarf_die_destroy(die);
1146 return -1;
1147 }
1148
1149 /**
1150 * Get the source location (file name and line number) for a given
1151 * address within a compile unit (CU).
1152 *
1153 * On success, the out parameter `src_loc` is set if found. On
1154 * failure, it remains unchanged.
1155 *
1156 * @param so bt_dwarf_cu instance for the compile unit which
1157 * may contain the address
1158 * @param addr Virtual memory address for which to find the
1159 * source location
1160 * @param src_loc Out parameter, the source location
1161 * @returns 0 on success, -1 on failure
1162 */
1163 static
1164 int so_info_lookup_cu_src_loc(struct bt_dwarf_cu *cu, uint64_t addr,
1165 struct source_location **src_loc)
1166 {
1167 int ret = 0;
1168 struct source_location *_src_loc = NULL;
1169
1170 if (!cu || !src_loc) {
1171 goto error;
1172 }
1173
1174 ret = so_info_lookup_cu_src_loc_inl(cu, addr, &_src_loc);
1175 if (ret) {
1176 goto error;
1177 }
1178
1179 if (_src_loc) {
1180 goto end;
1181 }
1182
1183 ret = so_info_lookup_cu_src_loc_no_inl(cu, addr, &_src_loc);
1184 if (ret) {
1185 goto error;
1186 }
1187
1188 if (_src_loc) {
1189 goto end;
1190 }
1191
1192 end:
1193 if (_src_loc) {
1194 *src_loc = _src_loc;
1195 }
1196
1197 return 0;
1198
1199 error:
1200 source_location_destroy(_src_loc);
1201 return -1;
1202 }
1203
1204 BT_HIDDEN
1205 int so_info_lookup_source_location(struct so_info *so, uint64_t addr,
1206 struct source_location **src_loc)
1207 {
1208 struct bt_dwarf_cu *cu = NULL;
1209 struct source_location *_src_loc = NULL;
1210
1211 if (!so || !src_loc) {
1212 goto error;
1213 }
1214
1215 /* Set DWARF info if it hasn't been accessed yet. */
1216 if (!so->dwarf_info && !so->is_elf_only) {
1217 if (so_info_set_dwarf_info(so)) {
1218 /* Failed to set DWARF info. */
1219 so->is_elf_only = true;
1220 }
1221 }
1222
1223 if (so->is_elf_only) {
1224 /* We cannot lookup source location without DWARF info. */
1225 goto error;
1226 }
1227
1228 if (!so_info_has_address(so, addr)) {
1229 goto error;
1230 }
1231
1232 /*
1233 * Addresses in ELF and DWARF are relative to base address for
1234 * PIC, so make the address argument relative too if needed.
1235 */
1236 if (so->is_pic) {
1237 addr -= so->low_addr;
1238 }
1239
1240 cu = bt_dwarf_cu_create(so->dwarf_info);
1241 if (!cu) {
1242 goto error;
1243 }
1244
1245 while (bt_dwarf_cu_next(cu) == 0) {
1246 int ret;
1247
1248 ret = so_info_lookup_cu_src_loc(cu, addr, &_src_loc);
1249 if (ret) {
1250 goto error;
1251 }
1252
1253 if (_src_loc) {
1254 break;
1255 }
1256 }
1257
1258 bt_dwarf_cu_destroy(cu);
1259 if (_src_loc) {
1260 *src_loc = _src_loc;
1261 }
1262
1263 return 0;
1264
1265 error:
1266 source_location_destroy(_src_loc);
1267 bt_dwarf_cu_destroy(cu);
1268 return -1;
1269 }
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