1 #include <fcntl.h>
2 #include <stdio.h>
3 #include <errno.h>
4 #include <string.h>
5 #include <unistd.h>
6 #include <inttypes.h>
7
8 #include "symbol.h"
9 #include "debug.h"
10
11 #ifndef HAVE_ELF_GETPHDRNUM
elf_getphdrnum(Elf * elf,size_t * dst)12 static int elf_getphdrnum(Elf *elf, size_t *dst)
13 {
14 GElf_Ehdr gehdr;
15 GElf_Ehdr *ehdr;
16
17 ehdr = gelf_getehdr(elf, &gehdr);
18 if (!ehdr)
19 return -1;
20
21 *dst = ehdr->e_phnum;
22
23 return 0;
24 }
25 #endif
26
27 #ifndef NT_GNU_BUILD_ID
28 #define NT_GNU_BUILD_ID 3
29 #endif
30
31 /**
32 * elf_symtab__for_each_symbol - iterate thru all the symbols
33 *
34 * @syms: struct elf_symtab instance to iterate
35 * @idx: uint32_t idx
36 * @sym: GElf_Sym iterator
37 */
38 #define elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) \
39 for (idx = 0, gelf_getsym(syms, idx, &sym);\
40 idx < nr_syms; \
41 idx++, gelf_getsym(syms, idx, &sym))
42
elf_sym__type(const GElf_Sym * sym)43 static inline uint8_t elf_sym__type(const GElf_Sym *sym)
44 {
45 return GELF_ST_TYPE(sym->st_info);
46 }
47
elf_sym__is_function(const GElf_Sym * sym)48 static inline int elf_sym__is_function(const GElf_Sym *sym)
49 {
50 return elf_sym__type(sym) == STT_FUNC &&
51 sym->st_name != 0 &&
52 sym->st_shndx != SHN_UNDEF;
53 }
54
elf_sym__is_object(const GElf_Sym * sym)55 static inline bool elf_sym__is_object(const GElf_Sym *sym)
56 {
57 return elf_sym__type(sym) == STT_OBJECT &&
58 sym->st_name != 0 &&
59 sym->st_shndx != SHN_UNDEF;
60 }
61
elf_sym__is_label(const GElf_Sym * sym)62 static inline int elf_sym__is_label(const GElf_Sym *sym)
63 {
64 return elf_sym__type(sym) == STT_NOTYPE &&
65 sym->st_name != 0 &&
66 sym->st_shndx != SHN_UNDEF &&
67 sym->st_shndx != SHN_ABS;
68 }
69
elf_sym__is_a(GElf_Sym * sym,enum map_type type)70 static bool elf_sym__is_a(GElf_Sym *sym, enum map_type type)
71 {
72 switch (type) {
73 case MAP__FUNCTION:
74 return elf_sym__is_function(sym);
75 case MAP__VARIABLE:
76 return elf_sym__is_object(sym);
77 default:
78 return false;
79 }
80 }
81
elf_sym__name(const GElf_Sym * sym,const Elf_Data * symstrs)82 static inline const char *elf_sym__name(const GElf_Sym *sym,
83 const Elf_Data *symstrs)
84 {
85 return symstrs->d_buf + sym->st_name;
86 }
87
elf_sec__name(const GElf_Shdr * shdr,const Elf_Data * secstrs)88 static inline const char *elf_sec__name(const GElf_Shdr *shdr,
89 const Elf_Data *secstrs)
90 {
91 return secstrs->d_buf + shdr->sh_name;
92 }
93
elf_sec__is_text(const GElf_Shdr * shdr,const Elf_Data * secstrs)94 static inline int elf_sec__is_text(const GElf_Shdr *shdr,
95 const Elf_Data *secstrs)
96 {
97 return strstr(elf_sec__name(shdr, secstrs), "text") != NULL;
98 }
99
elf_sec__is_data(const GElf_Shdr * shdr,const Elf_Data * secstrs)100 static inline bool elf_sec__is_data(const GElf_Shdr *shdr,
101 const Elf_Data *secstrs)
102 {
103 return strstr(elf_sec__name(shdr, secstrs), "data") != NULL;
104 }
105
elf_sec__is_a(GElf_Shdr * shdr,Elf_Data * secstrs,enum map_type type)106 static bool elf_sec__is_a(GElf_Shdr *shdr, Elf_Data *secstrs,
107 enum map_type type)
108 {
109 switch (type) {
110 case MAP__FUNCTION:
111 return elf_sec__is_text(shdr, secstrs);
112 case MAP__VARIABLE:
113 return elf_sec__is_data(shdr, secstrs);
114 default:
115 return false;
116 }
117 }
118
elf_addr_to_index(Elf * elf,GElf_Addr addr)119 static size_t elf_addr_to_index(Elf *elf, GElf_Addr addr)
120 {
121 Elf_Scn *sec = NULL;
122 GElf_Shdr shdr;
123 size_t cnt = 1;
124
125 while ((sec = elf_nextscn(elf, sec)) != NULL) {
126 gelf_getshdr(sec, &shdr);
127
128 if ((addr >= shdr.sh_addr) &&
129 (addr < (shdr.sh_addr + shdr.sh_size)))
130 return cnt;
131
132 ++cnt;
133 }
134
135 return -1;
136 }
137
elf_section_by_name(Elf * elf,GElf_Ehdr * ep,GElf_Shdr * shp,const char * name,size_t * idx)138 static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
139 GElf_Shdr *shp, const char *name,
140 size_t *idx)
141 {
142 Elf_Scn *sec = NULL;
143 size_t cnt = 1;
144
145 /* Elf is corrupted/truncated, avoid calling elf_strptr. */
146 if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL))
147 return NULL;
148
149 while ((sec = elf_nextscn(elf, sec)) != NULL) {
150 char *str;
151
152 gelf_getshdr(sec, shp);
153 str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
154 if (!strcmp(name, str)) {
155 if (idx)
156 *idx = cnt;
157 break;
158 }
159 ++cnt;
160 }
161
162 return sec;
163 }
164
165 #define elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_entries) \
166 for (idx = 0, pos = gelf_getrel(reldata, 0, &pos_mem); \
167 idx < nr_entries; \
168 ++idx, pos = gelf_getrel(reldata, idx, &pos_mem))
169
170 #define elf_section__for_each_rela(reldata, pos, pos_mem, idx, nr_entries) \
171 for (idx = 0, pos = gelf_getrela(reldata, 0, &pos_mem); \
172 idx < nr_entries; \
173 ++idx, pos = gelf_getrela(reldata, idx, &pos_mem))
174
175 /*
176 * We need to check if we have a .dynsym, so that we can handle the
177 * .plt, synthesizing its symbols, that aren't on the symtabs (be it
178 * .dynsym or .symtab).
179 * And always look at the original dso, not at debuginfo packages, that
180 * have the PLT data stripped out (shdr_rel_plt.sh_type == SHT_NOBITS).
181 */
dso__synthesize_plt_symbols(struct dso * dso,struct symsrc * ss,struct map * map,symbol_filter_t filter)182 int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss, struct map *map,
183 symbol_filter_t filter)
184 {
185 uint32_t nr_rel_entries, idx;
186 GElf_Sym sym;
187 u64 plt_offset;
188 GElf_Shdr shdr_plt;
189 struct symbol *f;
190 GElf_Shdr shdr_rel_plt, shdr_dynsym;
191 Elf_Data *reldata, *syms, *symstrs;
192 Elf_Scn *scn_plt_rel, *scn_symstrs, *scn_dynsym;
193 size_t dynsym_idx;
194 GElf_Ehdr ehdr;
195 char sympltname[1024];
196 Elf *elf;
197 int nr = 0, symidx, err = 0;
198
199 if (!ss->dynsym)
200 return 0;
201
202 elf = ss->elf;
203 ehdr = ss->ehdr;
204
205 scn_dynsym = ss->dynsym;
206 shdr_dynsym = ss->dynshdr;
207 dynsym_idx = ss->dynsym_idx;
208
209 if (scn_dynsym == NULL)
210 goto out_elf_end;
211
212 scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
213 ".rela.plt", NULL);
214 if (scn_plt_rel == NULL) {
215 scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
216 ".rel.plt", NULL);
217 if (scn_plt_rel == NULL)
218 goto out_elf_end;
219 }
220
221 err = -1;
222
223 if (shdr_rel_plt.sh_link != dynsym_idx)
224 goto out_elf_end;
225
226 if (elf_section_by_name(elf, &ehdr, &shdr_plt, ".plt", NULL) == NULL)
227 goto out_elf_end;
228
229 /*
230 * Fetch the relocation section to find the idxes to the GOT
231 * and the symbols in the .dynsym they refer to.
232 */
233 reldata = elf_getdata(scn_plt_rel, NULL);
234 if (reldata == NULL)
235 goto out_elf_end;
236
237 syms = elf_getdata(scn_dynsym, NULL);
238 if (syms == NULL)
239 goto out_elf_end;
240
241 scn_symstrs = elf_getscn(elf, shdr_dynsym.sh_link);
242 if (scn_symstrs == NULL)
243 goto out_elf_end;
244
245 symstrs = elf_getdata(scn_symstrs, NULL);
246 if (symstrs == NULL)
247 goto out_elf_end;
248
249 if (symstrs->d_size == 0)
250 goto out_elf_end;
251
252 nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize;
253 plt_offset = shdr_plt.sh_offset;
254
255 if (shdr_rel_plt.sh_type == SHT_RELA) {
256 GElf_Rela pos_mem, *pos;
257
258 elf_section__for_each_rela(reldata, pos, pos_mem, idx,
259 nr_rel_entries) {
260 symidx = GELF_R_SYM(pos->r_info);
261 plt_offset += shdr_plt.sh_entsize;
262 gelf_getsym(syms, symidx, &sym);
263 snprintf(sympltname, sizeof(sympltname),
264 "%s@plt", elf_sym__name(&sym, symstrs));
265
266 f = symbol__new(plt_offset, shdr_plt.sh_entsize,
267 STB_GLOBAL, sympltname);
268 if (!f)
269 goto out_elf_end;
270
271 if (filter && filter(map, f))
272 symbol__delete(f);
273 else {
274 symbols__insert(&dso->symbols[map->type], f);
275 ++nr;
276 }
277 }
278 } else if (shdr_rel_plt.sh_type == SHT_REL) {
279 GElf_Rel pos_mem, *pos;
280 elf_section__for_each_rel(reldata, pos, pos_mem, idx,
281 nr_rel_entries) {
282 symidx = GELF_R_SYM(pos->r_info);
283 plt_offset += shdr_plt.sh_entsize;
284 gelf_getsym(syms, symidx, &sym);
285 snprintf(sympltname, sizeof(sympltname),
286 "%s@plt", elf_sym__name(&sym, symstrs));
287
288 f = symbol__new(plt_offset, shdr_plt.sh_entsize,
289 STB_GLOBAL, sympltname);
290 if (!f)
291 goto out_elf_end;
292
293 if (filter && filter(map, f))
294 symbol__delete(f);
295 else {
296 symbols__insert(&dso->symbols[map->type], f);
297 ++nr;
298 }
299 }
300 }
301
302 err = 0;
303 out_elf_end:
304 if (err == 0)
305 return nr;
306 pr_debug("%s: problems reading %s PLT info.\n",
307 __func__, dso->long_name);
308 return 0;
309 }
310
311 /*
312 * Align offset to 4 bytes as needed for note name and descriptor data.
313 */
314 #define NOTE_ALIGN(n) (((n) + 3) & -4U)
315
elf_read_build_id(Elf * elf,void * bf,size_t size)316 static int elf_read_build_id(Elf *elf, void *bf, size_t size)
317 {
318 int err = -1;
319 GElf_Ehdr ehdr;
320 GElf_Shdr shdr;
321 Elf_Data *data;
322 Elf_Scn *sec;
323 Elf_Kind ek;
324 void *ptr;
325
326 if (size < BUILD_ID_SIZE)
327 goto out;
328
329 ek = elf_kind(elf);
330 if (ek != ELF_K_ELF)
331 goto out;
332
333 if (gelf_getehdr(elf, &ehdr) == NULL) {
334 pr_err("%s: cannot get elf header.\n", __func__);
335 goto out;
336 }
337
338 /*
339 * Check following sections for notes:
340 * '.note.gnu.build-id'
341 * '.notes'
342 * '.note' (VDSO specific)
343 */
344 do {
345 sec = elf_section_by_name(elf, &ehdr, &shdr,
346 ".note.gnu.build-id", NULL);
347 if (sec)
348 break;
349
350 sec = elf_section_by_name(elf, &ehdr, &shdr,
351 ".notes", NULL);
352 if (sec)
353 break;
354
355 sec = elf_section_by_name(elf, &ehdr, &shdr,
356 ".note", NULL);
357 if (sec)
358 break;
359
360 return err;
361
362 } while (0);
363
364 data = elf_getdata(sec, NULL);
365 if (data == NULL)
366 goto out;
367
368 ptr = data->d_buf;
369 while (ptr < (data->d_buf + data->d_size)) {
370 GElf_Nhdr *nhdr = ptr;
371 size_t namesz = NOTE_ALIGN(nhdr->n_namesz),
372 descsz = NOTE_ALIGN(nhdr->n_descsz);
373 const char *name;
374
375 ptr += sizeof(*nhdr);
376 name = ptr;
377 ptr += namesz;
378 if (nhdr->n_type == NT_GNU_BUILD_ID &&
379 nhdr->n_namesz == sizeof("GNU")) {
380 if (memcmp(name, "GNU", sizeof("GNU")) == 0) {
381 size_t sz = min(size, descsz);
382 memcpy(bf, ptr, sz);
383 memset(bf + sz, 0, size - sz);
384 err = descsz;
385 break;
386 }
387 }
388 ptr += descsz;
389 }
390
391 out:
392 return err;
393 }
394
filename__read_build_id(const char * filename,void * bf,size_t size)395 int filename__read_build_id(const char *filename, void *bf, size_t size)
396 {
397 int fd, err = -1;
398 Elf *elf;
399
400 if (size < BUILD_ID_SIZE)
401 goto out;
402
403 fd = open(filename, O_RDONLY);
404 if (fd < 0)
405 goto out;
406
407 elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
408 if (elf == NULL) {
409 pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
410 goto out_close;
411 }
412
413 err = elf_read_build_id(elf, bf, size);
414
415 elf_end(elf);
416 out_close:
417 close(fd);
418 out:
419 return err;
420 }
421
sysfs__read_build_id(const char * filename,void * build_id,size_t size)422 int sysfs__read_build_id(const char *filename, void *build_id, size_t size)
423 {
424 int fd, err = -1;
425
426 if (size < BUILD_ID_SIZE)
427 goto out;
428
429 fd = open(filename, O_RDONLY);
430 if (fd < 0)
431 goto out;
432
433 while (1) {
434 char bf[BUFSIZ];
435 GElf_Nhdr nhdr;
436 size_t namesz, descsz;
437
438 if (read(fd, &nhdr, sizeof(nhdr)) != sizeof(nhdr))
439 break;
440
441 namesz = NOTE_ALIGN(nhdr.n_namesz);
442 descsz = NOTE_ALIGN(nhdr.n_descsz);
443 if (nhdr.n_type == NT_GNU_BUILD_ID &&
444 nhdr.n_namesz == sizeof("GNU")) {
445 if (read(fd, bf, namesz) != (ssize_t)namesz)
446 break;
447 if (memcmp(bf, "GNU", sizeof("GNU")) == 0) {
448 size_t sz = min(descsz, size);
449 if (read(fd, build_id, sz) == (ssize_t)sz) {
450 memset(build_id + sz, 0, size - sz);
451 err = 0;
452 break;
453 }
454 } else if (read(fd, bf, descsz) != (ssize_t)descsz)
455 break;
456 } else {
457 int n = namesz + descsz;
458 if (read(fd, bf, n) != n)
459 break;
460 }
461 }
462 close(fd);
463 out:
464 return err;
465 }
466
filename__read_debuglink(const char * filename,char * debuglink,size_t size)467 int filename__read_debuglink(const char *filename, char *debuglink,
468 size_t size)
469 {
470 int fd, err = -1;
471 Elf *elf;
472 GElf_Ehdr ehdr;
473 GElf_Shdr shdr;
474 Elf_Data *data;
475 Elf_Scn *sec;
476 Elf_Kind ek;
477
478 fd = open(filename, O_RDONLY);
479 if (fd < 0)
480 goto out;
481
482 elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
483 if (elf == NULL) {
484 pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
485 goto out_close;
486 }
487
488 ek = elf_kind(elf);
489 if (ek != ELF_K_ELF)
490 goto out_close;
491
492 if (gelf_getehdr(elf, &ehdr) == NULL) {
493 pr_err("%s: cannot get elf header.\n", __func__);
494 goto out_close;
495 }
496
497 sec = elf_section_by_name(elf, &ehdr, &shdr,
498 ".gnu_debuglink", NULL);
499 if (sec == NULL)
500 goto out_close;
501
502 data = elf_getdata(sec, NULL);
503 if (data == NULL)
504 goto out_close;
505
506 /* the start of this section is a zero-terminated string */
507 strncpy(debuglink, data->d_buf, size);
508
509 elf_end(elf);
510
511 out_close:
512 close(fd);
513 out:
514 return err;
515 }
516
dso__swap_init(struct dso * dso,unsigned char eidata)517 static int dso__swap_init(struct dso *dso, unsigned char eidata)
518 {
519 static unsigned int const endian = 1;
520
521 dso->needs_swap = DSO_SWAP__NO;
522
523 switch (eidata) {
524 case ELFDATA2LSB:
525 /* We are big endian, DSO is little endian. */
526 if (*(unsigned char const *)&endian != 1)
527 dso->needs_swap = DSO_SWAP__YES;
528 break;
529
530 case ELFDATA2MSB:
531 /* We are little endian, DSO is big endian. */
532 if (*(unsigned char const *)&endian != 0)
533 dso->needs_swap = DSO_SWAP__YES;
534 break;
535
536 default:
537 pr_err("unrecognized DSO data encoding %d\n", eidata);
538 return -EINVAL;
539 }
540
541 return 0;
542 }
543
symsrc__possibly_runtime(struct symsrc * ss)544 bool symsrc__possibly_runtime(struct symsrc *ss)
545 {
546 return ss->dynsym || ss->opdsec;
547 }
548
symsrc__has_symtab(struct symsrc * ss)549 bool symsrc__has_symtab(struct symsrc *ss)
550 {
551 return ss->symtab != NULL;
552 }
553
symsrc__destroy(struct symsrc * ss)554 void symsrc__destroy(struct symsrc *ss)
555 {
556 free(ss->name);
557 elf_end(ss->elf);
558 close(ss->fd);
559 }
560
symsrc__init(struct symsrc * ss,struct dso * dso,const char * name,enum dso_binary_type type)561 int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
562 enum dso_binary_type type)
563 {
564 int err = -1;
565 GElf_Ehdr ehdr;
566 Elf *elf;
567 int fd;
568
569 fd = open(name, O_RDONLY);
570 if (fd < 0)
571 return -1;
572
573 elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
574 if (elf == NULL) {
575 pr_debug("%s: cannot read %s ELF file.\n", __func__, name);
576 goto out_close;
577 }
578
579 if (gelf_getehdr(elf, &ehdr) == NULL) {
580 pr_debug("%s: cannot get elf header.\n", __func__);
581 goto out_elf_end;
582 }
583
584 if (dso__swap_init(dso, ehdr.e_ident[EI_DATA]))
585 goto out_elf_end;
586
587 /* Always reject images with a mismatched build-id: */
588 if (dso->has_build_id) {
589 u8 build_id[BUILD_ID_SIZE];
590
591 if (elf_read_build_id(elf, build_id, BUILD_ID_SIZE) < 0)
592 goto out_elf_end;
593
594 if (!dso__build_id_equal(dso, build_id))
595 goto out_elf_end;
596 }
597
598 ss->symtab = elf_section_by_name(elf, &ehdr, &ss->symshdr, ".symtab",
599 NULL);
600 if (ss->symshdr.sh_type != SHT_SYMTAB)
601 ss->symtab = NULL;
602
603 ss->dynsym_idx = 0;
604 ss->dynsym = elf_section_by_name(elf, &ehdr, &ss->dynshdr, ".dynsym",
605 &ss->dynsym_idx);
606 if (ss->dynshdr.sh_type != SHT_DYNSYM)
607 ss->dynsym = NULL;
608
609 ss->opdidx = 0;
610 ss->opdsec = elf_section_by_name(elf, &ehdr, &ss->opdshdr, ".opd",
611 &ss->opdidx);
612 if (ss->opdshdr.sh_type != SHT_PROGBITS)
613 ss->opdsec = NULL;
614
615 if (dso->kernel == DSO_TYPE_USER) {
616 GElf_Shdr shdr;
617 ss->adjust_symbols = (ehdr.e_type == ET_EXEC ||
618 ehdr.e_type == ET_REL ||
619 elf_section_by_name(elf, &ehdr, &shdr,
620 ".gnu.prelink_undo",
621 NULL) != NULL);
622 } else {
623 ss->adjust_symbols = ehdr.e_type == ET_EXEC ||
624 ehdr.e_type == ET_REL;
625 }
626
627 ss->name = strdup(name);
628 if (!ss->name)
629 goto out_elf_end;
630
631 ss->elf = elf;
632 ss->fd = fd;
633 ss->ehdr = ehdr;
634 ss->type = type;
635
636 return 0;
637
638 out_elf_end:
639 elf_end(elf);
640 out_close:
641 close(fd);
642 return err;
643 }
644
645 /**
646 * ref_reloc_sym_not_found - has kernel relocation symbol been found.
647 * @kmap: kernel maps and relocation reference symbol
648 *
649 * This function returns %true if we are dealing with the kernel maps and the
650 * relocation reference symbol has not yet been found. Otherwise %false is
651 * returned.
652 */
ref_reloc_sym_not_found(struct kmap * kmap)653 static bool ref_reloc_sym_not_found(struct kmap *kmap)
654 {
655 return kmap && kmap->ref_reloc_sym && kmap->ref_reloc_sym->name &&
656 !kmap->ref_reloc_sym->unrelocated_addr;
657 }
658
659 /**
660 * ref_reloc - kernel relocation offset.
661 * @kmap: kernel maps and relocation reference symbol
662 *
663 * This function returns the offset of kernel addresses as determined by using
664 * the relocation reference symbol i.e. if the kernel has not been relocated
665 * then the return value is zero.
666 */
ref_reloc(struct kmap * kmap)667 static u64 ref_reloc(struct kmap *kmap)
668 {
669 if (kmap && kmap->ref_reloc_sym &&
670 kmap->ref_reloc_sym->unrelocated_addr)
671 return kmap->ref_reloc_sym->addr -
672 kmap->ref_reloc_sym->unrelocated_addr;
673 return 0;
674 }
675
dso__load_sym(struct dso * dso,struct map * map,struct symsrc * syms_ss,struct symsrc * runtime_ss,symbol_filter_t filter,int kmodule)676 int dso__load_sym(struct dso *dso, struct map *map,
677 struct symsrc *syms_ss, struct symsrc *runtime_ss,
678 symbol_filter_t filter, int kmodule)
679 {
680 struct kmap *kmap = dso->kernel ? map__kmap(map) : NULL;
681 struct map *curr_map = map;
682 struct dso *curr_dso = dso;
683 Elf_Data *symstrs, *secstrs;
684 uint32_t nr_syms;
685 int err = -1;
686 uint32_t idx;
687 GElf_Ehdr ehdr;
688 GElf_Shdr shdr;
689 Elf_Data *syms, *opddata = NULL;
690 GElf_Sym sym;
691 Elf_Scn *sec, *sec_strndx;
692 Elf *elf;
693 int nr = 0;
694 bool remap_kernel = false, adjust_kernel_syms = false;
695
696 dso->symtab_type = syms_ss->type;
697 dso->rel = syms_ss->ehdr.e_type == ET_REL;
698
699 /*
700 * Modules may already have symbols from kallsyms, but those symbols
701 * have the wrong values for the dso maps, so remove them.
702 */
703 if (kmodule && syms_ss->symtab)
704 symbols__delete(&dso->symbols[map->type]);
705
706 if (!syms_ss->symtab) {
707 syms_ss->symtab = syms_ss->dynsym;
708 syms_ss->symshdr = syms_ss->dynshdr;
709 }
710
711 elf = syms_ss->elf;
712 ehdr = syms_ss->ehdr;
713 sec = syms_ss->symtab;
714 shdr = syms_ss->symshdr;
715
716 if (runtime_ss->opdsec)
717 opddata = elf_rawdata(runtime_ss->opdsec, NULL);
718
719 syms = elf_getdata(sec, NULL);
720 if (syms == NULL)
721 goto out_elf_end;
722
723 sec = elf_getscn(elf, shdr.sh_link);
724 if (sec == NULL)
725 goto out_elf_end;
726
727 symstrs = elf_getdata(sec, NULL);
728 if (symstrs == NULL)
729 goto out_elf_end;
730
731 sec_strndx = elf_getscn(elf, ehdr.e_shstrndx);
732 if (sec_strndx == NULL)
733 goto out_elf_end;
734
735 secstrs = elf_getdata(sec_strndx, NULL);
736 if (secstrs == NULL)
737 goto out_elf_end;
738
739 nr_syms = shdr.sh_size / shdr.sh_entsize;
740
741 memset(&sym, 0, sizeof(sym));
742
743 /*
744 * The kernel relocation symbol is needed in advance in order to adjust
745 * kernel maps correctly.
746 */
747 if (ref_reloc_sym_not_found(kmap)) {
748 elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
749 const char *elf_name = elf_sym__name(&sym, symstrs);
750
751 if (strcmp(elf_name, kmap->ref_reloc_sym->name))
752 continue;
753 kmap->ref_reloc_sym->unrelocated_addr = sym.st_value;
754 break;
755 }
756 }
757
758 dso->adjust_symbols = runtime_ss->adjust_symbols || ref_reloc(kmap);
759 /*
760 * Initial kernel and module mappings do not map to the dso. For
761 * function mappings, flag the fixups.
762 */
763 if (map->type == MAP__FUNCTION && (dso->kernel || kmodule)) {
764 remap_kernel = true;
765 adjust_kernel_syms = dso->adjust_symbols;
766 }
767 elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
768 struct symbol *f;
769 const char *elf_name = elf_sym__name(&sym, symstrs);
770 char *demangled = NULL;
771 int is_label = elf_sym__is_label(&sym);
772 const char *section_name;
773 bool used_opd = false;
774
775 if (!is_label && !elf_sym__is_a(&sym, map->type))
776 continue;
777
778 /* Reject ARM ELF "mapping symbols": these aren't unique and
779 * don't identify functions, so will confuse the profile
780 * output: */
781 if (ehdr.e_machine == EM_ARM) {
782 if (!strcmp(elf_name, "$a") ||
783 !strcmp(elf_name, "$d") ||
784 !strcmp(elf_name, "$t"))
785 continue;
786 }
787
788 if (runtime_ss->opdsec && sym.st_shndx == runtime_ss->opdidx) {
789 u32 offset = sym.st_value - syms_ss->opdshdr.sh_addr;
790 u64 *opd = opddata->d_buf + offset;
791 sym.st_value = DSO__SWAP(dso, u64, *opd);
792 sym.st_shndx = elf_addr_to_index(runtime_ss->elf,
793 sym.st_value);
794 used_opd = true;
795 }
796 /*
797 * When loading symbols in a data mapping, ABS symbols (which
798 * has a value of SHN_ABS in its st_shndx) failed at
799 * elf_getscn(). And it marks the loading as a failure so
800 * already loaded symbols cannot be fixed up.
801 *
802 * I'm not sure what should be done. Just ignore them for now.
803 * - Namhyung Kim
804 */
805 if (sym.st_shndx == SHN_ABS)
806 continue;
807
808 sec = elf_getscn(runtime_ss->elf, sym.st_shndx);
809 if (!sec)
810 goto out_elf_end;
811
812 gelf_getshdr(sec, &shdr);
813
814 if (is_label && !elf_sec__is_a(&shdr, secstrs, map->type))
815 continue;
816
817 section_name = elf_sec__name(&shdr, secstrs);
818
819 /* On ARM, symbols for thumb functions have 1 added to
820 * the symbol address as a flag - remove it */
821 if ((ehdr.e_machine == EM_ARM) &&
822 (map->type == MAP__FUNCTION) &&
823 (sym.st_value & 1))
824 --sym.st_value;
825
826 if (dso->kernel || kmodule) {
827 char dso_name[PATH_MAX];
828
829 /* Adjust symbol to map to file offset */
830 if (adjust_kernel_syms)
831 sym.st_value -= shdr.sh_addr - shdr.sh_offset;
832
833 if (strcmp(section_name,
834 (curr_dso->short_name +
835 dso->short_name_len)) == 0)
836 goto new_symbol;
837
838 if (strcmp(section_name, ".text") == 0) {
839 /*
840 * The initial kernel mapping is based on
841 * kallsyms and identity maps. Overwrite it to
842 * map to the kernel dso.
843 */
844 if (remap_kernel && dso->kernel) {
845 remap_kernel = false;
846 map->start = shdr.sh_addr +
847 ref_reloc(kmap);
848 map->end = map->start + shdr.sh_size;
849 map->pgoff = shdr.sh_offset;
850 map->map_ip = map__map_ip;
851 map->unmap_ip = map__unmap_ip;
852 /* Ensure maps are correctly ordered */
853 map_groups__remove(kmap->kmaps, map);
854 map_groups__insert(kmap->kmaps, map);
855 }
856
857 /*
858 * The initial module mapping is based on
859 * /proc/modules mapped to offset zero.
860 * Overwrite it to map to the module dso.
861 */
862 if (remap_kernel && kmodule) {
863 remap_kernel = false;
864 map->pgoff = shdr.sh_offset;
865 }
866
867 curr_map = map;
868 curr_dso = dso;
869 goto new_symbol;
870 }
871
872 if (!kmap)
873 goto new_symbol;
874
875 snprintf(dso_name, sizeof(dso_name),
876 "%s%s", dso->short_name, section_name);
877
878 curr_map = map_groups__find_by_name(kmap->kmaps, map->type, dso_name);
879 if (curr_map == NULL) {
880 u64 start = sym.st_value;
881
882 if (kmodule)
883 start += map->start + shdr.sh_offset;
884
885 curr_dso = dso__new(dso_name);
886 if (curr_dso == NULL)
887 goto out_elf_end;
888 curr_dso->kernel = dso->kernel;
889 curr_dso->long_name = dso->long_name;
890 curr_dso->long_name_len = dso->long_name_len;
891 curr_map = map__new2(start, curr_dso,
892 map->type);
893 if (curr_map == NULL) {
894 dso__delete(curr_dso);
895 goto out_elf_end;
896 }
897 if (adjust_kernel_syms) {
898 curr_map->start = shdr.sh_addr +
899 ref_reloc(kmap);
900 curr_map->end = curr_map->start +
901 shdr.sh_size;
902 curr_map->pgoff = shdr.sh_offset;
903 } else {
904 curr_map->map_ip = identity__map_ip;
905 curr_map->unmap_ip = identity__map_ip;
906 }
907 curr_dso->symtab_type = dso->symtab_type;
908 map_groups__insert(kmap->kmaps, curr_map);
909 dsos__add(&dso->node, curr_dso);
910 dso__set_loaded(curr_dso, map->type);
911 } else
912 curr_dso = curr_map->dso;
913
914 goto new_symbol;
915 }
916
917 if ((used_opd && runtime_ss->adjust_symbols)
918 || (!used_opd && syms_ss->adjust_symbols)) {
919 pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
920 "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
921 (u64)sym.st_value, (u64)shdr.sh_addr,
922 (u64)shdr.sh_offset);
923 sym.st_value -= shdr.sh_addr - shdr.sh_offset;
924 }
925 /*
926 * We need to figure out if the object was created from C++ sources
927 * DWARF DW_compile_unit has this, but we don't always have access
928 * to it...
929 */
930 if (symbol_conf.demangle) {
931 demangled = bfd_demangle(NULL, elf_name,
932 DMGL_PARAMS | DMGL_ANSI);
933 if (demangled != NULL)
934 elf_name = demangled;
935 }
936 new_symbol:
937 f = symbol__new(sym.st_value, sym.st_size,
938 GELF_ST_BIND(sym.st_info), elf_name);
939 free(demangled);
940 if (!f)
941 goto out_elf_end;
942
943 if (filter && filter(curr_map, f))
944 symbol__delete(f);
945 else {
946 symbols__insert(&curr_dso->symbols[curr_map->type], f);
947 nr++;
948 }
949 }
950
951 /*
952 * For misannotated, zeroed, ASM function sizes.
953 */
954 if (nr > 0) {
955 symbols__fixup_duplicate(&dso->symbols[map->type]);
956 symbols__fixup_end(&dso->symbols[map->type]);
957 if (kmap) {
958 /*
959 * We need to fixup this here too because we create new
960 * maps here, for things like vsyscall sections.
961 */
962 __map_groups__fixup_end(kmap->kmaps, map->type);
963 }
964 }
965 err = nr;
966 out_elf_end:
967 return err;
968 }
969
elf_read_maps(Elf * elf,bool exe,mapfn_t mapfn,void * data)970 static int elf_read_maps(Elf *elf, bool exe, mapfn_t mapfn, void *data)
971 {
972 GElf_Phdr phdr;
973 size_t i, phdrnum;
974 int err;
975 u64 sz;
976
977 if (elf_getphdrnum(elf, &phdrnum))
978 return -1;
979
980 for (i = 0; i < phdrnum; i++) {
981 if (gelf_getphdr(elf, i, &phdr) == NULL)
982 return -1;
983 if (phdr.p_type != PT_LOAD)
984 continue;
985 if (exe) {
986 if (!(phdr.p_flags & PF_X))
987 continue;
988 } else {
989 if (!(phdr.p_flags & PF_R))
990 continue;
991 }
992 sz = min(phdr.p_memsz, phdr.p_filesz);
993 if (!sz)
994 continue;
995 err = mapfn(phdr.p_vaddr, sz, phdr.p_offset, data);
996 if (err)
997 return err;
998 }
999 return 0;
1000 }
1001
file__read_maps(int fd,bool exe,mapfn_t mapfn,void * data,bool * is_64_bit)1002 int file__read_maps(int fd, bool exe, mapfn_t mapfn, void *data,
1003 bool *is_64_bit)
1004 {
1005 int err;
1006 Elf *elf;
1007
1008 elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
1009 if (elf == NULL)
1010 return -1;
1011
1012 if (is_64_bit)
1013 *is_64_bit = (gelf_getclass(elf) == ELFCLASS64);
1014
1015 err = elf_read_maps(elf, exe, mapfn, data);
1016
1017 elf_end(elf);
1018 return err;
1019 }
1020
symbol__elf_init(void)1021 void symbol__elf_init(void)
1022 {
1023 elf_version(EV_CURRENT);
1024 }
1025