tools/perf/util/symbol-elf.c

   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 }