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 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 43 static inline uint8_t elf_sym__type(const GElf_Sym *sym) 44 { 45 return GELF_ST_TYPE(sym->st_info); 46 } 47 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 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 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 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 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 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 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 } 99 100 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 } 105 106 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 } 118 119 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 } 137 138 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 */ 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) 315 316 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 } 394 395 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 } 421 422 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 } 466 467 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 } 516 517 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 } 543 544 bool symsrc__possibly_runtime(struct symsrc *ss) 545 { 546 return ss->dynsym || ss->opdsec; 547 } 548 549 bool symsrc__has_symtab(struct symsrc *ss) 550 { 551 return ss->symtab != NULL; 552 } 553 554 void symsrc__destroy(struct symsrc *ss) 555 { 556 free(ss->name); 557 elf_end(ss->elf); 558 close(ss->fd); 559 } 560 561 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 */ 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 */ 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 } 675 676 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 } 969 970 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 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 1021 void symbol__elf_init(void) 1022 { 1023 elf_version(EV_CURRENT); 1024 } 1025
