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 "demangle-java.h"
  10 #include "demangle-rust.h"
  11 #include "machine.h"
  12 #include "vdso.h"
  13 #include <symbol/kallsyms.h>
  14 #include "debug.h"
  15
  16 #ifndef EM_AARCH64
  17 #define EM_AARCH64      183  /* ARM 64 bit */
  18 #endif
  19
  20 typedef Elf64_Nhdr GElf_Nhdr;
  21
  22 #ifdef HAVE_CPLUS_DEMANGLE_SUPPORT
  23 extern char *cplus_demangle(const char *, int);
  24
  25 static inline char *bfd_demangle(void __maybe_unused *v, const char *c, int i)
  26 {
  27         return cplus_demangle(c, i);
  28 }
  29 #else
  30 #ifdef NO_DEMANGLE
  31 static inline char *bfd_demangle(void __maybe_unused *v,
  32                                  const char __maybe_unused *c,
  33                                  int __maybe_unused i)
  34 {
  35         return NULL;
  36 }
  37 #else
  38 #define PACKAGE 'perf'
  39 #include <bfd.h>
  40 #endif
  41 #endif
  42
  43 #ifndef HAVE_ELF_GETPHDRNUM_SUPPORT
  44 static int elf_getphdrnum(Elf *elf, size_t *dst)
  45 {
  46         GElf_Ehdr gehdr;
  47         GElf_Ehdr *ehdr;
  48
  49         ehdr = gelf_getehdr(elf, &gehdr);
  50         if (!ehdr)
  51                 return -1;
  52
  53         *dst = ehdr->e_phnum;
  54
  55         return 0;
  56 }
  57 #endif
  58
  59 #ifndef HAVE_ELF_GETSHDRSTRNDX_SUPPORT
  60 static int elf_getshdrstrndx(Elf *elf __maybe_unused, size_t *dst __maybe_unused)
  61 {
  62         pr_err("%s: update your libelf to > 0.140, this one lacks elf_getshdrstrndx().\n", __func__);
  63         return -1;
  64 }
  65 #endif
  66
  67 #ifndef NT_GNU_BUILD_ID
  68 #define NT_GNU_BUILD_ID 3
  69 #endif
  70
  71 /**
  72  * elf_symtab__for_each_symbol - iterate thru all the symbols
  73  *
  74  * @syms: struct elf_symtab instance to iterate
  75  * @idx: uint32_t idx
  76  * @sym: GElf_Sym iterator
  77  */
  78 #define elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) \
  79         for (idx = 0, gelf_getsym(syms, idx, &sym);\
  80              idx < nr_syms; \
  81              idx++, gelf_getsym(syms, idx, &sym))
  82
  83 static inline uint8_t elf_sym__type(const GElf_Sym *sym)
  84 {
  85         return GELF_ST_TYPE(sym->st_info);
  86 }
  87
  88 #ifndef STT_GNU_IFUNC
  89 #define STT_GNU_IFUNC 10
  90 #endif
  91
  92 static inline int elf_sym__is_function(const GElf_Sym *sym)
  93 {
  94         return (elf_sym__type(sym) == STT_FUNC ||
  95                 elf_sym__type(sym) == STT_GNU_IFUNC) &&
  96                sym->st_name != 0 &&
  97                sym->st_shndx != SHN_UNDEF;
  98 }
  99
 100 static inline bool elf_sym__is_object(const GElf_Sym *sym)
 101 {
 102         return elf_sym__type(sym) == STT_OBJECT &&
 103                 sym->st_name != 0 &&
 104                 sym->st_shndx != SHN_UNDEF;
 105 }
 106
 107 static inline int elf_sym__is_label(const GElf_Sym *sym)
 108 {
 109         return elf_sym__type(sym) == STT_NOTYPE &&
 110                 sym->st_name != 0 &&
 111                 sym->st_shndx != SHN_UNDEF &&
 112                 sym->st_shndx != SHN_ABS;
 113 }
 114
 115 static bool elf_sym__is_a(GElf_Sym *sym, enum map_type type)
 116 {
 117         switch (type) {
 118         case MAP__FUNCTION:
 119                 return elf_sym__is_function(sym);
 120         case MAP__VARIABLE:
 121                 return elf_sym__is_object(sym);
 122         default:
 123                 return false;
 124         }
 125 }
 126
 127 static inline const char *elf_sym__name(const GElf_Sym *sym,
 128                                         const Elf_Data *symstrs)
 129 {
 130         return symstrs->d_buf + sym->st_name;
 131 }
 132
 133 static inline const char *elf_sec__name(const GElf_Shdr *shdr,
 134                                         const Elf_Data *secstrs)
 135 {
 136         return secstrs->d_buf + shdr->sh_name;
 137 }
 138
 139 static inline int elf_sec__is_text(const GElf_Shdr *shdr,
 140                                         const Elf_Data *secstrs)
 141 {
 142         return strstr(elf_sec__name(shdr, secstrs), "text") != NULL;
 143 }
 144
 145 static inline bool elf_sec__is_data(const GElf_Shdr *shdr,
 146                                     const Elf_Data *secstrs)
 147 {
 148         return strstr(elf_sec__name(shdr, secstrs), "data") != NULL;
 149 }
 150
 151 static bool elf_sec__is_a(GElf_Shdr *shdr, Elf_Data *secstrs,
 152                           enum map_type type)
 153 {
 154         switch (type) {
 155         case MAP__FUNCTION:
 156                 return elf_sec__is_text(shdr, secstrs);
 157         case MAP__VARIABLE:
 158                 return elf_sec__is_data(shdr, secstrs);
 159         default:
 160                 return false;
 161         }
 162 }
 163
 164 static size_t elf_addr_to_index(Elf *elf, GElf_Addr addr)
 165 {
 166         Elf_Scn *sec = NULL;
 167         GElf_Shdr shdr;
 168         size_t cnt = 1;
 169
 170         while ((sec = elf_nextscn(elf, sec)) != NULL) {
 171                 gelf_getshdr(sec, &shdr);
 172
 173                 if ((addr >= shdr.sh_addr) &&
 174                     (addr < (shdr.sh_addr + shdr.sh_size)))
 175                         return cnt;
 176
 177                 ++cnt;
 178         }
 179
 180         return -1;
 181 }
 182
 183 Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
 184                              GElf_Shdr *shp, const char *name, size_t *idx)
 185 {
 186         Elf_Scn *sec = NULL;
 187         size_t cnt = 1;
 188
 189         /* Elf is corrupted/truncated, avoid calling elf_strptr. */
 190         if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL))
 191                 return NULL;
 192
 193         while ((sec = elf_nextscn(elf, sec)) != NULL) {
 194                 char *str;
 195
 196                 gelf_getshdr(sec, shp);
 197                 str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
 198                 if (str && !strcmp(name, str)) {
 199                         if (idx)
 200                                 *idx = cnt;
 201                         return sec;
 202                 }
 203                 ++cnt;
 204         }
 205
 206         return NULL;
 207 }
 208
 209 #define elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_entries) \
 210         for (idx = 0, pos = gelf_getrel(reldata, 0, &pos_mem); \
 211              idx < nr_entries; \
 212              ++idx, pos = gelf_getrel(reldata, idx, &pos_mem))
 213
 214 #define elf_section__for_each_rela(reldata, pos, pos_mem, idx, nr_entries) \
 215         for (idx = 0, pos = gelf_getrela(reldata, 0, &pos_mem); \
 216              idx < nr_entries; \
 217              ++idx, pos = gelf_getrela(reldata, idx, &pos_mem))
 218
 219 /*
 220  * We need to check if we have a .dynsym, so that we can handle the
 221  * .plt, synthesizing its symbols, that aren't on the symtabs (be it
 222  * .dynsym or .symtab).
 223  * And always look at the original dso, not at debuginfo packages, that
 224  * have the PLT data stripped out (shdr_rel_plt.sh_type == SHT_NOBITS).
 225  */
 226 int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss, struct map *map,
 227                                 symbol_filter_t filter)
 228 {
 229         uint32_t nr_rel_entries, idx;
 230         GElf_Sym sym;
 231         u64 plt_offset;
 232         GElf_Shdr shdr_plt;
 233         struct symbol *f;
 234         GElf_Shdr shdr_rel_plt, shdr_dynsym;
 235         Elf_Data *reldata, *syms, *symstrs;
 236         Elf_Scn *scn_plt_rel, *scn_symstrs, *scn_dynsym;
 237         size_t dynsym_idx;
 238         GElf_Ehdr ehdr;
 239         char sympltname[1024];
 240         Elf *elf;
 241         int nr = 0, symidx, err = 0;
 242
 243         if (!ss->dynsym)
 244                 return 0;
 245
 246         elf = ss->elf;
 247         ehdr = ss->ehdr;
 248
 249         scn_dynsym = ss->dynsym;
 250         shdr_dynsym = ss->dynshdr;
 251         dynsym_idx = ss->dynsym_idx;
 252
 253         if (scn_dynsym == NULL)
 254                 goto out_elf_end;
 255
 256         scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
 257                                           ".rela.plt", NULL);
 258         if (scn_plt_rel == NULL) {
 259                 scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
 260                                                   ".rel.plt", NULL);
 261                 if (scn_plt_rel == NULL)
 262                         goto out_elf_end;
 263         }
 264
 265         err = -1;
 266
 267         if (shdr_rel_plt.sh_link != dynsym_idx)
 268                 goto out_elf_end;
 269
 270         if (elf_section_by_name(elf, &ehdr, &shdr_plt, ".plt", NULL) == NULL)
 271                 goto out_elf_end;
 272
 273         /*
 274          * Fetch the relocation section to find the idxes to the GOT
 275          * and the symbols in the .dynsym they refer to.
 276          */
 277         reldata = elf_getdata(scn_plt_rel, NULL);
 278         if (reldata == NULL)
 279                 goto out_elf_end;
 280
 281         syms = elf_getdata(scn_dynsym, NULL);
 282         if (syms == NULL)
 283                 goto out_elf_end;
 284
 285         scn_symstrs = elf_getscn(elf, shdr_dynsym.sh_link);
 286         if (scn_symstrs == NULL)
 287                 goto out_elf_end;
 288
 289         symstrs = elf_getdata(scn_symstrs, NULL);
 290         if (symstrs == NULL)
 291                 goto out_elf_end;
 292
 293         if (symstrs->d_size == 0)
 294                 goto out_elf_end;
 295
 296         nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize;
 297         plt_offset = shdr_plt.sh_offset;
 298
 299         if (shdr_rel_plt.sh_type == SHT_RELA) {
 300                 GElf_Rela pos_mem, *pos;
 301
 302                 elf_section__for_each_rela(reldata, pos, pos_mem, idx,
 303                                            nr_rel_entries) {
 304                         symidx = GELF_R_SYM(pos->r_info);
 305                         plt_offset += shdr_plt.sh_entsize;
 306                         gelf_getsym(syms, symidx, &sym);
 307                         snprintf(sympltname, sizeof(sympltname),
 308                                  "%s@plt", elf_sym__name(&sym, symstrs));
 309
 310                         f = symbol__new(plt_offset, shdr_plt.sh_entsize,
 311                                         STB_GLOBAL, sympltname);
 312                         if (!f)
 313                                 goto out_elf_end;
 314
 315                         if (filter && filter(map, f))
 316                                 symbol__delete(f);
 317                         else {
 318                                 symbols__insert(&dso->symbols[map->type], f);
 319                                 ++nr;
 320                         }
 321                 }
 322         } else if (shdr_rel_plt.sh_type == SHT_REL) {
 323                 GElf_Rel pos_mem, *pos;
 324                 elf_section__for_each_rel(reldata, pos, pos_mem, idx,
 325                                           nr_rel_entries) {
 326                         symidx = GELF_R_SYM(pos->r_info);
 327                         plt_offset += shdr_plt.sh_entsize;
 328                         gelf_getsym(syms, symidx, &sym);
 329                         snprintf(sympltname, sizeof(sympltname),
 330                                  "%s@plt", elf_sym__name(&sym, symstrs));
 331
 332                         f = symbol__new(plt_offset, shdr_plt.sh_entsize,
 333                                         STB_GLOBAL, sympltname);
 334                         if (!f)
 335                                 goto out_elf_end;
 336
 337                         if (filter && filter(map, f))
 338                                 symbol__delete(f);
 339                         else {
 340                                 symbols__insert(&dso->symbols[map->type], f);
 341                                 ++nr;
 342                         }
 343                 }
 344         }
 345
 346         err = 0;
 347 out_elf_end:
 348         if (err == 0)
 349                 return nr;
 350         pr_debug("%s: problems reading %s PLT info.\n",
 351                  __func__, dso->long_name);
 352         return 0;
 353 }
 354
 355 /*
 356  * Align offset to 4 bytes as needed for note name and descriptor data.
 357  */
 358 #define NOTE_ALIGN(n) (((n) + 3) & -4U)
 359
 360 static int elf_read_build_id(Elf *elf, void *bf, size_t size)
 361 {
 362         int err = -1;
 363         GElf_Ehdr ehdr;
 364         GElf_Shdr shdr;
 365         Elf_Data *data;
 366         Elf_Scn *sec;
 367         Elf_Kind ek;
 368         void *ptr;
 369
 370         if (size < BUILD_ID_SIZE)
 371                 goto out;
 372
 373         ek = elf_kind(elf);
 374         if (ek != ELF_K_ELF)
 375                 goto out;
 376
 377         if (gelf_getehdr(elf, &ehdr) == NULL) {
 378                 pr_err("%s: cannot get elf header.\n", __func__);
 379                 goto out;
 380         }
 381
 382         /*
 383          * Check following sections for notes:
 384          *   '.note.gnu.build-id'
 385          *   '.notes'
 386          *   '.note' (VDSO specific)
 387          */
 388         do {
 389                 sec = elf_section_by_name(elf, &ehdr, &shdr,
 390                                           ".note.gnu.build-id", NULL);
 391                 if (sec)
 392                         break;
 393
 394                 sec = elf_section_by_name(elf, &ehdr, &shdr,
 395                                           ".notes", NULL);
 396                 if (sec)
 397                         break;
 398
 399                 sec = elf_section_by_name(elf, &ehdr, &shdr,
 400                                           ".note", NULL);
 401                 if (sec)
 402                         break;
 403
 404                 return err;
 405
 406         } while (0);
 407
 408         data = elf_getdata(sec, NULL);
 409         if (data == NULL)
 410                 goto out;
 411
 412         ptr = data->d_buf;
 413         while (ptr < (data->d_buf + data->d_size)) {
 414                 GElf_Nhdr *nhdr = ptr;
 415                 size_t namesz = NOTE_ALIGN(nhdr->n_namesz),
 416                        descsz = NOTE_ALIGN(nhdr->n_descsz);
 417                 const char *name;
 418
 419                 ptr += sizeof(*nhdr);
 420                 name = ptr;
 421                 ptr += namesz;
 422                 if (nhdr->n_type == NT_GNU_BUILD_ID &&
 423                     nhdr->n_namesz == sizeof("GNU")) {
 424                         if (memcmp(name, "GNU", sizeof("GNU")) == 0) {
 425                                 size_t sz = min(size, descsz);
 426                                 memcpy(bf, ptr, sz);
 427                                 memset(bf + sz, 0, size - sz);
 428                                 err = descsz;
 429                                 break;
 430                         }
 431                 }
 432                 ptr += descsz;
 433         }
 434
 435 out:
 436         return err;
 437 }
 438
 439 int filename__read_build_id(const char *filename, void *bf, size_t size)
 440 {
 441         int fd, err = -1;
 442         Elf *elf;
 443
 444         if (size < BUILD_ID_SIZE)
 445                 goto out;
 446
 447         fd = open(filename, O_RDONLY);
 448         if (fd < 0)
 449                 goto out;
 450
 451         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
 452         if (elf == NULL) {
 453                 pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
 454                 goto out_close;
 455         }
 456
 457         err = elf_read_build_id(elf, bf, size);
 458
 459         elf_end(elf);
 460 out_close:
 461         close(fd);
 462 out:
 463         return err;
 464 }
 465
 466 int sysfs__read_build_id(const char *filename, void *build_id, size_t size)
 467 {
 468         int fd, err = -1;
 469
 470         if (size < BUILD_ID_SIZE)
 471                 goto out;
 472
 473         fd = open(filename, O_RDONLY);
 474         if (fd < 0)
 475                 goto out;
 476
 477         while (1) {
 478                 char bf[BUFSIZ];
 479                 GElf_Nhdr nhdr;
 480                 size_t namesz, descsz;
 481
 482                 if (read(fd, &nhdr, sizeof(nhdr)) != sizeof(nhdr))
 483                         break;
 484
 485                 namesz = NOTE_ALIGN(nhdr.n_namesz);
 486                 descsz = NOTE_ALIGN(nhdr.n_descsz);
 487                 if (nhdr.n_type == NT_GNU_BUILD_ID &&
 488                     nhdr.n_namesz == sizeof("GNU")) {
 489                         if (read(fd, bf, namesz) != (ssize_t)namesz)
 490                                 break;
 491                         if (memcmp(bf, "GNU", sizeof("GNU")) == 0) {
 492                                 size_t sz = min(descsz, size);
 493                                 if (read(fd, build_id, sz) == (ssize_t)sz) {
 494                                         memset(build_id + sz, 0, size - sz);
 495                                         err = 0;
 496                                         break;
 497                                 }
 498                         } else if (read(fd, bf, descsz) != (ssize_t)descsz)
 499                                 break;
 500                 } else {
 501                         int n = namesz + descsz;
 502                         if (read(fd, bf, n) != n)
 503                                 break;
 504                 }
 505         }
 506         close(fd);
 507 out:
 508         return err;
 509 }
 510
 511 int filename__read_debuglink(const char *filename, char *debuglink,
 512                              size_t size)
 513 {
 514         int fd, err = -1;
 515         Elf *elf;
 516         GElf_Ehdr ehdr;
 517         GElf_Shdr shdr;
 518         Elf_Data *data;
 519         Elf_Scn *sec;
 520         Elf_Kind ek;
 521
 522         fd = open(filename, O_RDONLY);
 523         if (fd < 0)
 524                 goto out;
 525
 526         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
 527         if (elf == NULL) {
 528                 pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
 529                 goto out_close;
 530         }
 531
 532         ek = elf_kind(elf);
 533         if (ek != ELF_K_ELF)
 534                 goto out_elf_end;
 535
 536         if (gelf_getehdr(elf, &ehdr) == NULL) {
 537                 pr_err("%s: cannot get elf header.\n", __func__);
 538                 goto out_elf_end;
 539         }
 540
 541         sec = elf_section_by_name(elf, &ehdr, &shdr,
 542                                   ".gnu_debuglink", NULL);
 543         if (sec == NULL)
 544                 goto out_elf_end;
 545
 546         data = elf_getdata(sec, NULL);
 547         if (data == NULL)
 548                 goto out_elf_end;
 549
 550         /* the start of this section is a zero-terminated string */
 551         strncpy(debuglink, data->d_buf, size);
 552
 553         err = 0;
 554
 555 out_elf_end:
 556         elf_end(elf);
 557 out_close:
 558         close(fd);
 559 out:
 560         return err;
 561 }
 562
 563 static int dso__swap_init(struct dso *dso, unsigned char eidata)
 564 {
 565         static unsigned int const endian = 1;
 566
 567         dso->needs_swap = DSO_SWAP__NO;
 568
 569         switch (eidata) {
 570         case ELFDATA2LSB:
 571                 /* We are big endian, DSO is little endian. */
 572                 if (*(unsigned char const *)&endian != 1)
 573                         dso->needs_swap = DSO_SWAP__YES;
 574                 break;
 575
 576         case ELFDATA2MSB:
 577                 /* We are little endian, DSO is big endian. */
 578                 if (*(unsigned char const *)&endian != 0)
 579                         dso->needs_swap = DSO_SWAP__YES;
 580                 break;
 581
 582         default:
 583                 pr_err("unrecognized DSO data encoding %d\n", eidata);
 584                 return -EINVAL;
 585         }
 586
 587         return 0;
 588 }
 589
 590 static int decompress_kmodule(struct dso *dso, const char *name,
 591                               enum dso_binary_type type)
 592 {
 593         int fd = -1;
 594         char tmpbuf[] = "/tmp/perf-kmod-XXXXXX";
 595         struct kmod_path m;
 596
 597         if (type != DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP &&
 598             type != DSO_BINARY_TYPE__GUEST_KMODULE_COMP &&
 599             type != DSO_BINARY_TYPE__BUILD_ID_CACHE)
 600                 return -1;
 601
 602         if (type == DSO_BINARY_TYPE__BUILD_ID_CACHE)
 603                 name = dso->long_name;
 604
 605         if (kmod_path__parse_ext(&m, name) || !m.comp)
 606                 return -1;
 607
 608         fd = mkstemp(tmpbuf);
 609         if (fd < 0) {
 610                 dso->load_errno = errno;
 611                 goto out;
 612         }
 613
 614         if (!decompress_to_file(m.ext, name, fd)) {
 615                 dso->load_errno = DSO_LOAD_ERRNO__DECOMPRESSION_FAILURE;
 616                 close(fd);
 617                 fd = -1;
 618         }
 619
 620         unlink(tmpbuf);
 621
 622 out:
 623         free(m.ext);
 624         return fd;
 625 }
 626
 627 bool symsrc__possibly_runtime(struct symsrc *ss)
 628 {
 629         return ss->dynsym || ss->opdsec;
 630 }
 631
 632 bool symsrc__has_symtab(struct symsrc *ss)
 633 {
 634         return ss->symtab != NULL;
 635 }
 636
 637 void symsrc__destroy(struct symsrc *ss)
 638 {
 639         zfree(&ss->name);
 640         elf_end(ss->elf);
 641         close(ss->fd);
 642 }
 643
 644 bool __weak elf__needs_adjust_symbols(GElf_Ehdr ehdr)
 645 {
 646         return ehdr.e_type == ET_EXEC || ehdr.e_type == ET_REL;
 647 }
 648
 649 int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
 650                  enum dso_binary_type type)
 651 {
 652         int err = -1;
 653         GElf_Ehdr ehdr;
 654         Elf *elf;
 655         int fd;
 656
 657         if (dso__needs_decompress(dso)) {
 658                 fd = decompress_kmodule(dso, name, type);
 659                 if (fd < 0)
 660                         return -1;
 661         } else {
 662                 fd = open(name, O_RDONLY);
 663                 if (fd < 0) {
 664                         dso->load_errno = errno;
 665                         return -1;
 666                 }
 667         }
 668
 669         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
 670         if (elf == NULL) {
 671                 pr_debug("%s: cannot read %s ELF file.\n", __func__, name);
 672                 dso->load_errno = DSO_LOAD_ERRNO__INVALID_ELF;
 673                 goto out_close;
 674         }
 675
 676         if (gelf_getehdr(elf, &ehdr) == NULL) {
 677                 dso->load_errno = DSO_LOAD_ERRNO__INVALID_ELF;
 678                 pr_debug("%s: cannot get elf header.\n", __func__);
 679                 goto out_elf_end;
 680         }
 681
 682         if (dso__swap_init(dso, ehdr.e_ident[EI_DATA])) {
 683                 dso->load_errno = DSO_LOAD_ERRNO__INTERNAL_ERROR;
 684                 goto out_elf_end;
 685         }
 686
 687         /* Always reject images with a mismatched build-id: */
 688         if (dso->has_build_id) {
 689                 u8 build_id[BUILD_ID_SIZE];
 690
 691                 if (elf_read_build_id(elf, build_id, BUILD_ID_SIZE) < 0) {
 692                         dso->load_errno = DSO_LOAD_ERRNO__CANNOT_READ_BUILDID;
 693                         goto out_elf_end;
 694                 }
 695
 696                 if (!dso__build_id_equal(dso, build_id)) {
 697                         pr_debug("%s: build id mismatch for %s.\n", __func__, name);
 698                         dso->load_errno = DSO_LOAD_ERRNO__MISMATCHING_BUILDID;
 699                         goto out_elf_end;
 700                 }
 701         }
 702
 703         ss->is_64_bit = (gelf_getclass(elf) == ELFCLASS64);
 704
 705         ss->symtab = elf_section_by_name(elf, &ehdr, &ss->symshdr, ".symtab",
 706                         NULL);
 707         if (ss->symshdr.sh_type != SHT_SYMTAB)
 708                 ss->symtab = NULL;
 709
 710         ss->dynsym_idx = 0;
 711         ss->dynsym = elf_section_by_name(elf, &ehdr, &ss->dynshdr, ".dynsym",
 712                         &ss->dynsym_idx);
 713         if (ss->dynshdr.sh_type != SHT_DYNSYM)
 714                 ss->dynsym = NULL;
 715
 716         ss->opdidx = 0;
 717         ss->opdsec = elf_section_by_name(elf, &ehdr, &ss->opdshdr, ".opd",
 718                         &ss->opdidx);
 719         if (ss->opdshdr.sh_type != SHT_PROGBITS)
 720                 ss->opdsec = NULL;
 721
 722         if (dso->kernel == DSO_TYPE_USER)
 723                 ss->adjust_symbols = true;
 724         else
 725                 ss->adjust_symbols = elf__needs_adjust_symbols(ehdr);
 726
 727         ss->name   = strdup(name);
 728         if (!ss->name) {
 729                 dso->load_errno = errno;
 730                 goto out_elf_end;
 731         }
 732
 733         ss->elf    = elf;
 734         ss->fd     = fd;
 735         ss->ehdr   = ehdr;
 736         ss->type   = type;
 737
 738         return 0;
 739
 740 out_elf_end:
 741         elf_end(elf);
 742 out_close:
 743         close(fd);
 744         return err;
 745 }
 746
 747 /**
 748  * ref_reloc_sym_not_found - has kernel relocation symbol been found.
 749  * @kmap: kernel maps and relocation reference symbol
 750  *
 751  * This function returns %true if we are dealing with the kernel maps and the
 752  * relocation reference symbol has not yet been found.  Otherwise %false is
 753  * returned.
 754  */
 755 static bool ref_reloc_sym_not_found(struct kmap *kmap)
 756 {
 757         return kmap && kmap->ref_reloc_sym && kmap->ref_reloc_sym->name &&
 758                !kmap->ref_reloc_sym->unrelocated_addr;
 759 }
 760
 761 /**
 762  * ref_reloc - kernel relocation offset.
 763  * @kmap: kernel maps and relocation reference symbol
 764  *
 765  * This function returns the offset of kernel addresses as determined by using
 766  * the relocation reference symbol i.e. if the kernel has not been relocated
 767  * then the return value is zero.
 768  */
 769 static u64 ref_reloc(struct kmap *kmap)
 770 {
 771         if (kmap && kmap->ref_reloc_sym &&
 772             kmap->ref_reloc_sym->unrelocated_addr)
 773                 return kmap->ref_reloc_sym->addr -
 774                        kmap->ref_reloc_sym->unrelocated_addr;
 775         return 0;
 776 }
 777
 778 static bool want_demangle(bool is_kernel_sym)
 779 {
 780         return is_kernel_sym ? symbol_conf.demangle_kernel : symbol_conf.demangle;
 781 }
 782
 783 void __weak arch__sym_update(struct symbol *s __maybe_unused,
 784                 GElf_Sym *sym __maybe_unused) { }
 785
 786 int dso__load_sym(struct dso *dso, struct map *map,
 787                   struct symsrc *syms_ss, struct symsrc *runtime_ss,
 788                   symbol_filter_t filter, int kmodule)
 789 {
 790         struct kmap *kmap = dso->kernel ? map__kmap(map) : NULL;
 791         struct map_groups *kmaps = kmap ? map__kmaps(map) : NULL;
 792         struct map *curr_map = map;
 793         struct dso *curr_dso = dso;
 794         Elf_Data *symstrs, *secstrs;
 795         uint32_t nr_syms;
 796         int err = -1;
 797         uint32_t idx;
 798         GElf_Ehdr ehdr;
 799         GElf_Shdr shdr;
 800         GElf_Shdr tshdr;
 801         Elf_Data *syms, *opddata = NULL;
 802         GElf_Sym sym;
 803         Elf_Scn *sec, *sec_strndx;
 804         Elf *elf;
 805         int nr = 0;
 806         bool remap_kernel = false, adjust_kernel_syms = false;
 807
 808         if (kmap && !kmaps)
 809                 return -1;
 810
 811         dso->symtab_type = syms_ss->type;
 812         dso->is_64_bit = syms_ss->is_64_bit;
 813         dso->rel = syms_ss->ehdr.e_type == ET_REL;
 814
 815         /*
 816          * Modules may already have symbols from kallsyms, but those symbols
 817          * have the wrong values for the dso maps, so remove them.
 818          */
 819         if (kmodule && syms_ss->symtab)
 820                 symbols__delete(&dso->symbols[map->type]);
 821
 822         if (!syms_ss->symtab) {
 823                 /*
 824                  * If the vmlinux is stripped, fail so we will fall back
 825                  * to using kallsyms. The vmlinux runtime symbols aren't
 826                  * of much use.
 827                  */
 828                 if (dso->kernel)
 829                         goto out_elf_end;
 830
 831                 syms_ss->symtab  = syms_ss->dynsym;
 832                 syms_ss->symshdr = syms_ss->dynshdr;
 833         }
 834
 835         elf = syms_ss->elf;
 836         ehdr = syms_ss->ehdr;
 837         sec = syms_ss->symtab;
 838         shdr = syms_ss->symshdr;
 839
 840         if (elf_section_by_name(runtime_ss->elf, &runtime_ss->ehdr, &tshdr,
 841                                 ".text", NULL))
 842                 dso->text_offset = tshdr.sh_addr - tshdr.sh_offset;
 843
 844         if (runtime_ss->opdsec)
 845                 opddata = elf_rawdata(runtime_ss->opdsec, NULL);
 846
 847         syms = elf_getdata(sec, NULL);
 848         if (syms == NULL)
 849                 goto out_elf_end;
 850
 851         sec = elf_getscn(elf, shdr.sh_link);
 852         if (sec == NULL)
 853                 goto out_elf_end;
 854
 855         symstrs = elf_getdata(sec, NULL);
 856         if (symstrs == NULL)
 857                 goto out_elf_end;
 858
 859         sec_strndx = elf_getscn(runtime_ss->elf, runtime_ss->ehdr.e_shstrndx);
 860         if (sec_strndx == NULL)
 861                 goto out_elf_end;
 862
 863         secstrs = elf_getdata(sec_strndx, NULL);
 864         if (secstrs == NULL)
 865                 goto out_elf_end;
 866
 867         nr_syms = shdr.sh_size / shdr.sh_entsize;
 868
 869         memset(&sym, 0, sizeof(sym));
 870
 871         /*
 872          * The kernel relocation symbol is needed in advance in order to adjust
 873          * kernel maps correctly.
 874          */
 875         if (ref_reloc_sym_not_found(kmap)) {
 876                 elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
 877                         const char *elf_name = elf_sym__name(&sym, symstrs);
 878
 879                         if (strcmp(elf_name, kmap->ref_reloc_sym->name))
 880                                 continue;
 881                         kmap->ref_reloc_sym->unrelocated_addr = sym.st_value;
 882                         map->reloc = kmap->ref_reloc_sym->addr -
 883                                      kmap->ref_reloc_sym->unrelocated_addr;
 884                         break;
 885                 }
 886         }
 887
 888         /*
 889          * Handle any relocation of vdso necessary because older kernels
 890          * attempted to prelink vdso to its virtual address.
 891          */
 892         if (dso__is_vdso(dso))
 893                 map->reloc = map->start - dso->text_offset;
 894
 895         dso->adjust_symbols = runtime_ss->adjust_symbols || ref_reloc(kmap);
 896         /*
 897          * Initial kernel and module mappings do not map to the dso.  For
 898          * function mappings, flag the fixups.
 899          */
 900         if (map->type == MAP__FUNCTION && (dso->kernel || kmodule)) {
 901                 remap_kernel = true;
 902                 adjust_kernel_syms = dso->adjust_symbols;
 903         }
 904         elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
 905                 struct symbol *f;
 906                 const char *elf_name = elf_sym__name(&sym, symstrs);
 907                 char *demangled = NULL;
 908                 int is_label = elf_sym__is_label(&sym);
 909                 const char *section_name;
 910                 bool used_opd = false;
 911
 912                 if (!is_label && !elf_sym__is_a(&sym, map->type))
 913                         continue;
 914
 915                 /* Reject ARM ELF "mapping symbols": these aren't unique and
 916                  * don't identify functions, so will confuse the profile
 917                  * output: */
 918                 if (ehdr.e_machine == EM_ARM || ehdr.e_machine == EM_AARCH64) {
 919                         if (elf_name[0] == '$' && strchr("adtx", elf_name[1])
 920                             && (elf_name[2] == '\0' || elf_name[2] == '.'))
 921                                 continue;
 922                 }
 923
 924                 if (runtime_ss->opdsec && sym.st_shndx == runtime_ss->opdidx) {
 925                         u32 offset = sym.st_value - syms_ss->opdshdr.sh_addr;
 926                         u64 *opd = opddata->d_buf + offset;
 927                         sym.st_value = DSO__SWAP(dso, u64, *opd);
 928                         sym.st_shndx = elf_addr_to_index(runtime_ss->elf,
 929                                         sym.st_value);
 930                         used_opd = true;
 931                 }
 932                 /*
 933                  * When loading symbols in a data mapping, ABS symbols (which
 934                  * has a value of SHN_ABS in its st_shndx) failed at
 935                  * elf_getscn().  And it marks the loading as a failure so
 936                  * already loaded symbols cannot be fixed up.
 937                  *
 938                  * I'm not sure what should be done. Just ignore them for now.
 939                  * - Namhyung Kim
 940                  */
 941                 if (sym.st_shndx == SHN_ABS)
 942                         continue;
 943
 944                 sec = elf_getscn(runtime_ss->elf, sym.st_shndx);
 945                 if (!sec)
 946                         goto out_elf_end;
 947
 948                 gelf_getshdr(sec, &shdr);
 949
 950                 if (is_label && !elf_sec__is_a(&shdr, secstrs, map->type))
 951                         continue;
 952
 953                 section_name = elf_sec__name(&shdr, secstrs);
 954
 955                 /* On ARM, symbols for thumb functions have 1 added to
 956                  * the symbol address as a flag - remove it */
 957                 if ((ehdr.e_machine == EM_ARM) &&
 958                     (map->type == MAP__FUNCTION) &&
 959                     (sym.st_value & 1))
 960                         --sym.st_value;
 961
 962                 if (dso->kernel || kmodule) {
 963                         char dso_name[PATH_MAX];
 964
 965                         /* Adjust symbol to map to file offset */
 966                         if (adjust_kernel_syms)
 967                                 sym.st_value -= shdr.sh_addr - shdr.sh_offset;
 968
 969                         if (strcmp(section_name,
 970                                    (curr_dso->short_name +
 971                                     dso->short_name_len)) == 0)
 972                                 goto new_symbol;
 973
 974                         if (strcmp(section_name, ".text") == 0) {
 975                                 /*
 976                                  * The initial kernel mapping is based on
 977                                  * kallsyms and identity maps.  Overwrite it to
 978                                  * map to the kernel dso.
 979                                  */
 980                                 if (remap_kernel && dso->kernel) {
 981                                         remap_kernel = false;
 982                                         map->start = shdr.sh_addr +
 983                                                      ref_reloc(kmap);
 984                                         map->end = map->start + shdr.sh_size;
 985                                         map->pgoff = shdr.sh_offset;
 986                                         map->map_ip = map__map_ip;
 987                                         map->unmap_ip = map__unmap_ip;
 988                                         /* Ensure maps are correctly ordered */
 989                                         if (kmaps) {
 990                                                 map__get(map);
 991                                                 map_groups__remove(kmaps, map);
 992                                                 map_groups__insert(kmaps, map);
 993                                                 map__put(map);
 994                                         }
 995                                 }
 996
 997                                 /*
 998                                  * The initial module mapping is based on
 999                                  * /proc/modules mapped to offset zero.
1000                                  * Overwrite it to map to the module dso.
1001                                  */
1002                                 if (remap_kernel && kmodule) {
1003                                         remap_kernel = false;
1004                                         map->pgoff = shdr.sh_offset;
1005                                 }
1006
1007                                 curr_map = map;
1008                                 curr_dso = dso;
1009                                 goto new_symbol;
1010                         }
1011
1012                         if (!kmap)
1013                                 goto new_symbol;
1014
1015                         snprintf(dso_name, sizeof(dso_name),
1016                                  "%s%s", dso->short_name, section_name);
1017
1018                         curr_map = map_groups__find_by_name(kmaps, map->type, dso_name);
1019                         if (curr_map == NULL) {
1020                                 u64 start = sym.st_value;
1021
1022                                 if (kmodule)
1023                                         start += map->start + shdr.sh_offset;
1024
1025                                 curr_dso = dso__new(dso_name);
1026                                 if (curr_dso == NULL)
1027                                         goto out_elf_end;
1028                                 curr_dso->kernel = dso->kernel;
1029                                 curr_dso->long_name = dso->long_name;
1030                                 curr_dso->long_name_len = dso->long_name_len;
1031                                 curr_map = map__new2(start, curr_dso,
1032                                                      map->type);
1033                                 dso__put(curr_dso);
1034                                 if (curr_map == NULL) {
1035                                         goto out_elf_end;
1036                                 }
1037                                 if (adjust_kernel_syms) {
1038                                         curr_map->start = shdr.sh_addr +
1039                                                           ref_reloc(kmap);
1040                                         curr_map->end = curr_map->start +
1041                                                         shdr.sh_size;
1042                                         curr_map->pgoff = shdr.sh_offset;
1043                                 } else {
1044                                         curr_map->map_ip = identity__map_ip;
1045                                         curr_map->unmap_ip = identity__map_ip;
1046                                 }
1047                                 curr_dso->symtab_type = dso->symtab_type;
1048                                 map_groups__insert(kmaps, curr_map);
1049                                 /*
1050                                  * Add it before we drop the referece to curr_map,
1051                                  * i.e. while we still are sure to have a reference
1052                                  * to this DSO via curr_map->dso.
1053                                  */
1054                                 dsos__add(&map->groups->machine->dsos, curr_dso);
1055                                 /* kmaps already got it */
1056                                 map__put(curr_map);
1057                                 dso__set_loaded(curr_dso, map->type);
1058                         } else
1059                                 curr_dso = curr_map->dso;
1060
1061                         goto new_symbol;
1062                 }
1063
1064                 if ((used_opd && runtime_ss->adjust_symbols)
1065                                 || (!used_opd && syms_ss->adjust_symbols)) {
1066                         pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
1067                                   "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
1068                                   (u64)sym.st_value, (u64)shdr.sh_addr,
1069                                   (u64)shdr.sh_offset);
1070                         sym.st_value -= shdr.sh_addr - shdr.sh_offset;
1071                 }
1072 new_symbol:
1073                 /*
1074                  * We need to figure out if the object was created from C++ sources
1075                  * DWARF DW_compile_unit has this, but we don't always have access
1076                  * to it...
1077                  */
1078                 if (want_demangle(dso->kernel || kmodule)) {
1079                         int demangle_flags = DMGL_NO_OPTS;
1080                         if (verbose)
1081                                 demangle_flags = DMGL_PARAMS | DMGL_ANSI;
1082
1083                         demangled = bfd_demangle(NULL, elf_name, demangle_flags);
1084                         if (demangled == NULL)
1085                                 demangled = java_demangle_sym(elf_name, JAVA_DEMANGLE_NORET);
1086                         else if (rust_is_mangled(demangled))
1087                                 /*
1088                                  * Input to Rust demangling is the BFD-demangled
1089                                  * name which it Rust-demangles in place.
1090                                  */
1091                                 rust_demangle_sym(demangled);
1092
1093                         if (demangled != NULL)
1094                                 elf_name = demangled;
1095                 }
1096                 f = symbol__new(sym.st_value, sym.st_size,
1097                                 GELF_ST_BIND(sym.st_info), elf_name);
1098                 free(demangled);
1099                 if (!f)
1100                         goto out_elf_end;
1101
1102                 arch__sym_update(f, &sym);
1103
1104                 if (filter && filter(curr_map, f))
1105                         symbol__delete(f);
1106                 else {
1107                         symbols__insert(&curr_dso->symbols[curr_map->type], f);
1108                         nr++;
1109                 }
1110         }
1111
1112         /*
1113          * For misannotated, zeroed, ASM function sizes.
1114          */
1115         if (nr > 0) {
1116                 if (!symbol_conf.allow_aliases)
1117                         symbols__fixup_duplicate(&dso->symbols[map->type]);
1118                 symbols__fixup_end(&dso->symbols[map->type]);
1119                 if (kmap) {
1120                         /*
1121                          * We need to fixup this here too because we create new
1122                          * maps here, for things like vsyscall sections.
1123                          */
1124                         __map_groups__fixup_end(kmaps, map->type);
1125                 }
1126         }
1127         err = nr;
1128 out_elf_end:
1129         return err;
1130 }
1131
1132 static int elf_read_maps(Elf *elf, bool exe, mapfn_t mapfn, void *data)
1133 {
1134         GElf_Phdr phdr;
1135         size_t i, phdrnum;
1136         int err;
1137         u64 sz;
1138
1139         if (elf_getphdrnum(elf, &phdrnum))
1140                 return -1;
1141
1142         for (i = 0; i < phdrnum; i++) {
1143                 if (gelf_getphdr(elf, i, &phdr) == NULL)
1144                         return -1;
1145                 if (phdr.p_type != PT_LOAD)
1146                         continue;
1147                 if (exe) {
1148                         if (!(phdr.p_flags & PF_X))
1149                                 continue;
1150                 } else {
1151                         if (!(phdr.p_flags & PF_R))
1152                                 continue;
1153                 }
1154                 sz = min(phdr.p_memsz, phdr.p_filesz);
1155                 if (!sz)
1156                         continue;
1157                 err = mapfn(phdr.p_vaddr, sz, phdr.p_offset, data);
1158                 if (err)
1159                         return err;
1160         }
1161         return 0;
1162 }
1163
1164 int file__read_maps(int fd, bool exe, mapfn_t mapfn, void *data,
1165                     bool *is_64_bit)
1166 {
1167         int err;
1168         Elf *elf;
1169
1170         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
1171         if (elf == NULL)
1172                 return -1;
1173
1174         if (is_64_bit)
1175                 *is_64_bit = (gelf_getclass(elf) == ELFCLASS64);
1176
1177         err = elf_read_maps(elf, exe, mapfn, data);
1178
1179         elf_end(elf);
1180         return err;
1181 }
1182
1183 enum dso_type dso__type_fd(int fd)
1184 {
1185         enum dso_type dso_type = DSO__TYPE_UNKNOWN;
1186         GElf_Ehdr ehdr;
1187         Elf_Kind ek;
1188         Elf *elf;
1189
1190         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
1191         if (elf == NULL)
1192                 goto out;
1193
1194         ek = elf_kind(elf);
1195         if (ek != ELF_K_ELF)
1196                 goto out_end;
1197
1198         if (gelf_getclass(elf) == ELFCLASS64) {
1199                 dso_type = DSO__TYPE_64BIT;
1200                 goto out_end;
1201         }
1202
1203         if (gelf_getehdr(elf, &ehdr) == NULL)
1204                 goto out_end;
1205
1206         if (ehdr.e_machine == EM_X86_64)
1207                 dso_type = DSO__TYPE_X32BIT;
1208         else
1209                 dso_type = DSO__TYPE_32BIT;
1210 out_end:
1211         elf_end(elf);
1212 out:
1213         return dso_type;
1214 }
1215
1216 static int copy_bytes(int from, off_t from_offs, int to, off_t to_offs, u64 len)
1217 {
1218         ssize_t r;
1219         size_t n;
1220         int err = -1;
1221         char *buf = malloc(page_size);
1222
1223         if (buf == NULL)
1224                 return -1;
1225
1226         if (lseek(to, to_offs, SEEK_SET) != to_offs)
1227                 goto out;
1228
1229         if (lseek(from, from_offs, SEEK_SET) != from_offs)
1230                 goto out;
1231
1232         while (len) {
1233                 n = page_size;
1234                 if (len < n)
1235                         n = len;
1236                 /* Use read because mmap won't work on proc files */
1237                 r = read(from, buf, n);
1238                 if (r < 0)
1239                         goto out;
1240                 if (!r)
1241                         break;
1242                 n = r;
1243                 r = write(to, buf, n);
1244                 if (r < 0)
1245                         goto out;
1246                 if ((size_t)r != n)
1247                         goto out;
1248                 len -= n;
1249         }
1250
1251         err = 0;
1252 out:
1253         free(buf);
1254         return err;
1255 }
1256
1257 struct kcore {
1258         int fd;
1259         int elfclass;
1260         Elf *elf;
1261         GElf_Ehdr ehdr;
1262 };
1263
1264 static int kcore__open(struct kcore *kcore, const char *filename)
1265 {
1266         GElf_Ehdr *ehdr;
1267
1268         kcore->fd = open(filename, O_RDONLY);
1269         if (kcore->fd == -1)
1270                 return -1;
1271
1272         kcore->elf = elf_begin(kcore->fd, ELF_C_READ, NULL);
1273         if (!kcore->elf)
1274                 goto out_close;
1275
1276         kcore->elfclass = gelf_getclass(kcore->elf);
1277         if (kcore->elfclass == ELFCLASSNONE)
1278                 goto out_end;
1279
1280         ehdr = gelf_getehdr(kcore->elf, &kcore->ehdr);
1281         if (!ehdr)
1282                 goto out_end;
1283
1284         return 0;
1285
1286 out_end:
1287         elf_end(kcore->elf);
1288 out_close:
1289         close(kcore->fd);
1290         return -1;
1291 }
1292
1293 static int kcore__init(struct kcore *kcore, char *filename, int elfclass,
1294                        bool temp)
1295 {
1296         kcore->elfclass = elfclass;
1297
1298         if (temp)
1299                 kcore->fd = mkstemp(filename);
1300         else
1301                 kcore->fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0400);
1302         if (kcore->fd == -1)
1303                 return -1;
1304
1305         kcore->elf = elf_begin(kcore->fd, ELF_C_WRITE, NULL);
1306         if (!kcore->elf)
1307                 goto out_close;
1308
1309         if (!gelf_newehdr(kcore->elf, elfclass))
1310                 goto out_end;
1311
1312         memset(&kcore->ehdr, 0, sizeof(GElf_Ehdr));
1313
1314         return 0;
1315
1316 out_end:
1317         elf_end(kcore->elf);
1318 out_close:
1319         close(kcore->fd);
1320         unlink(filename);
1321         return -1;
1322 }
1323
1324 static void kcore__close(struct kcore *kcore)
1325 {
1326         elf_end(kcore->elf);
1327         close(kcore->fd);
1328 }
1329
1330 static int kcore__copy_hdr(struct kcore *from, struct kcore *to, size_t count)
1331 {
1332         GElf_Ehdr *ehdr = &to->ehdr;
1333         GElf_Ehdr *kehdr = &from->ehdr;
1334
1335         memcpy(ehdr->e_ident, kehdr->e_ident, EI_NIDENT);
1336         ehdr->e_type      = kehdr->e_type;
1337         ehdr->e_machine   = kehdr->e_machine;
1338         ehdr->e_version   = kehdr->e_version;
1339         ehdr->e_entry     = 0;
1340         ehdr->e_shoff     = 0;
1341         ehdr->e_flags     = kehdr->e_flags;
1342         ehdr->e_phnum     = count;
1343         ehdr->e_shentsize = 0;
1344         ehdr->e_shnum     = 0;
1345         ehdr->e_shstrndx  = 0;
1346
1347         if (from->elfclass == ELFCLASS32) {
1348                 ehdr->e_phoff     = sizeof(Elf32_Ehdr);
1349                 ehdr->e_ehsize    = sizeof(Elf32_Ehdr);
1350                 ehdr->e_phentsize = sizeof(Elf32_Phdr);
1351         } else {
1352                 ehdr->e_phoff     = sizeof(Elf64_Ehdr);
1353                 ehdr->e_ehsize    = sizeof(Elf64_Ehdr);
1354                 ehdr->e_phentsize = sizeof(Elf64_Phdr);
1355         }
1356
1357         if (!gelf_update_ehdr(to->elf, ehdr))
1358                 return -1;
1359
1360         if (!gelf_newphdr(to->elf, count))
1361                 return -1;
1362
1363         return 0;
1364 }
1365
1366 static int kcore__add_phdr(struct kcore *kcore, int idx, off_t offset,
1367                            u64 addr, u64 len)
1368 {
1369         GElf_Phdr phdr = {
1370                 .p_type         = PT_LOAD,
1371                 .p_flags        = PF_R | PF_W | PF_X,
1372                 .p_offset       = offset,
1373                 .p_vaddr        = addr,
1374                 .p_paddr        = 0,
1375                 .p_filesz       = len,
1376                 .p_memsz        = len,
1377                 .p_align        = page_size,
1378         };
1379
1380         if (!gelf_update_phdr(kcore->elf, idx, &phdr))
1381                 return -1;
1382
1383         return 0;
1384 }
1385
1386 static off_t kcore__write(struct kcore *kcore)
1387 {
1388         return elf_update(kcore->elf, ELF_C_WRITE);
1389 }
1390
1391 struct phdr_data {
1392         off_t offset;
1393         u64 addr;
1394         u64 len;
1395 };
1396
1397 struct kcore_copy_info {
1398         u64 stext;
1399         u64 etext;
1400         u64 first_symbol;
1401         u64 last_symbol;
1402         u64 first_module;
1403         u64 last_module_symbol;
1404         struct phdr_data kernel_map;
1405         struct phdr_data modules_map;
1406 };
1407
1408 static int kcore_copy__process_kallsyms(void *arg, const char *name, char type,
1409                                         u64 start)
1410 {
1411         struct kcore_copy_info *kci = arg;
1412
1413         if (!symbol_type__is_a(type, MAP__FUNCTION))
1414                 return 0;
1415
1416         if (strchr(name, '[')) {
1417                 if (start > kci->last_module_symbol)
1418                         kci->last_module_symbol = start;
1419                 return 0;
1420         }
1421
1422         if (!kci->first_symbol || start < kci->first_symbol)
1423                 kci->first_symbol = start;
1424
1425         if (!kci->last_symbol || start > kci->last_symbol)
1426                 kci->last_symbol = start;
1427
1428         if (!strcmp(name, "_stext")) {
1429                 kci->stext = start;
1430                 return 0;
1431         }
1432
1433         if (!strcmp(name, "_etext")) {
1434                 kci->etext = start;
1435                 return 0;
1436         }
1437
1438         return 0;
1439 }
1440
1441 static int kcore_copy__parse_kallsyms(struct kcore_copy_info *kci,
1442                                       const char *dir)
1443 {
1444         char kallsyms_filename[PATH_MAX];
1445
1446         scnprintf(kallsyms_filename, PATH_MAX, "%s/kallsyms", dir);
1447
1448         if (symbol__restricted_filename(kallsyms_filename, "/proc/kallsyms"))
1449                 return -1;
1450
1451         if (kallsyms__parse(kallsyms_filename, kci,
1452                             kcore_copy__process_kallsyms) < 0)
1453                 return -1;
1454
1455         return 0;
1456 }
1457
1458 static int kcore_copy__process_modules(void *arg,
1459                                        const char *name __maybe_unused,
1460                                        u64 start)
1461 {
1462         struct kcore_copy_info *kci = arg;
1463
1464         if (!kci->first_module || start < kci->first_module)
1465                 kci->first_module = start;
1466
1467         return 0;
1468 }
1469
1470 static int kcore_copy__parse_modules(struct kcore_copy_info *kci,
1471                                      const char *dir)
1472 {
1473         char modules_filename[PATH_MAX];
1474
1475         scnprintf(modules_filename, PATH_MAX, "%s/modules", dir);
1476
1477         if (symbol__restricted_filename(modules_filename, "/proc/modules"))
1478                 return -1;
1479
1480         if (modules__parse(modules_filename, kci,
1481                            kcore_copy__process_modules) < 0)
1482                 return -1;
1483
1484         return 0;
1485 }
1486
1487 static void kcore_copy__map(struct phdr_data *p, u64 start, u64 end, u64 pgoff,
1488                             u64 s, u64 e)
1489 {
1490         if (p->addr || s < start || s >= end)
1491                 return;
1492
1493         p->addr = s;
1494         p->offset = (s - start) + pgoff;
1495         p->len = e < end ? e - s : end - s;
1496 }
1497
1498 static int kcore_copy__read_map(u64 start, u64 len, u64 pgoff, void *data)
1499 {
1500         struct kcore_copy_info *kci = data;
1501         u64 end = start + len;
1502
1503         kcore_copy__map(&kci->kernel_map, start, end, pgoff, kci->stext,
1504                         kci->etext);
1505
1506         kcore_copy__map(&kci->modules_map, start, end, pgoff, kci->first_module,
1507                         kci->last_module_symbol);
1508
1509         return 0;
1510 }
1511
1512 static int kcore_copy__read_maps(struct kcore_copy_info *kci, Elf *elf)
1513 {
1514         if (elf_read_maps(elf, true, kcore_copy__read_map, kci) < 0)
1515                 return -1;
1516
1517         return 0;
1518 }
1519
1520 static int kcore_copy__calc_maps(struct kcore_copy_info *kci, const char *dir,
1521                                  Elf *elf)
1522 {
1523         if (kcore_copy__parse_kallsyms(kci, dir))
1524                 return -1;
1525
1526         if (kcore_copy__parse_modules(kci, dir))
1527                 return -1;
1528
1529         if (kci->stext)
1530                 kci->stext = round_down(kci->stext, page_size);
1531         else
1532                 kci->stext = round_down(kci->first_symbol, page_size);
1533
1534         if (kci->etext) {
1535                 kci->etext = round_up(kci->etext, page_size);
1536         } else if (kci->last_symbol) {
1537                 kci->etext = round_up(kci->last_symbol, page_size);
1538                 kci->etext += page_size;
1539         }
1540
1541         kci->first_module = round_down(kci->first_module, page_size);
1542
1543         if (kci->last_module_symbol) {
1544                 kci->last_module_symbol = round_up(kci->last_module_symbol,
1545                                                    page_size);
1546                 kci->last_module_symbol += page_size;
1547         }
1548
1549         if (!kci->stext || !kci->etext)
1550                 return -1;
1551
1552         if (kci->first_module && !kci->last_module_symbol)
1553                 return -1;
1554
1555         return kcore_copy__read_maps(kci, elf);
1556 }
1557
1558 static int kcore_copy__copy_file(const char *from_dir, const char *to_dir,
1559                                  const char *name)
1560 {
1561         char from_filename[PATH_MAX];
1562         char to_filename[PATH_MAX];
1563
1564         scnprintf(from_filename, PATH_MAX, "%s/%s", from_dir, name);
1565         scnprintf(to_filename, PATH_MAX, "%s/%s", to_dir, name);
1566
1567         return copyfile_mode(from_filename, to_filename, 0400);
1568 }
1569
1570 static int kcore_copy__unlink(const char *dir, const char *name)
1571 {
1572         char filename[PATH_MAX];
1573
1574         scnprintf(filename, PATH_MAX, "%s/%s", dir, name);
1575
1576         return unlink(filename);
1577 }
1578
1579 static int kcore_copy__compare_fds(int from, int to)
1580 {
1581         char *buf_from;
1582         char *buf_to;
1583         ssize_t ret;
1584         size_t len;
1585         int err = -1;
1586
1587         buf_from = malloc(page_size);
1588         buf_to = malloc(page_size);
1589         if (!buf_from || !buf_to)
1590                 goto out;
1591
1592         while (1) {
1593                 /* Use read because mmap won't work on proc files */
1594                 ret = read(from, buf_from, page_size);
1595                 if (ret < 0)
1596                         goto out;
1597
1598                 if (!ret)
1599                         break;
1600
1601                 len = ret;
1602
1603                 if (readn(to, buf_to, len) != (int)len)
1604                         goto out;
1605
1606                 if (memcmp(buf_from, buf_to, len))
1607                         goto out;
1608         }
1609
1610         err = 0;
1611 out:
1612         free(buf_to);
1613         free(buf_from);
1614         return err;
1615 }
1616
1617 static int kcore_copy__compare_files(const char *from_filename,
1618                                      const char *to_filename)
1619 {
1620         int from, to, err = -1;
1621
1622         from = open(from_filename, O_RDONLY);
1623         if (from < 0)
1624                 return -1;
1625
1626         to = open(to_filename, O_RDONLY);
1627         if (to < 0)
1628                 goto out_close_from;
1629
1630         err = kcore_copy__compare_fds(from, to);
1631
1632         close(to);
1633 out_close_from:
1634         close(from);
1635         return err;
1636 }
1637
1638 static int kcore_copy__compare_file(const char *from_dir, const char *to_dir,
1639                                     const char *name)
1640 {
1641         char from_filename[PATH_MAX];
1642         char to_filename[PATH_MAX];
1643
1644         scnprintf(from_filename, PATH_MAX, "%s/%s", from_dir, name);
1645         scnprintf(to_filename, PATH_MAX, "%s/%s", to_dir, name);
1646
1647         return kcore_copy__compare_files(from_filename, to_filename);
1648 }
1649
1650 /**
1651  * kcore_copy - copy kallsyms, modules and kcore from one directory to another.
1652  * @from_dir: from directory
1653  * @to_dir: to directory
1654  *
1655  * This function copies kallsyms, modules and kcore files from one directory to
1656  * another.  kallsyms and modules are copied entirely.  Only code segments are
1657  * copied from kcore.  It is assumed that two segments suffice: one for the
1658  * kernel proper and one for all the modules.  The code segments are determined
1659  * from kallsyms and modules files.  The kernel map starts at _stext or the
1660  * lowest function symbol, and ends at _etext or the highest function symbol.
1661  * The module map starts at the lowest module address and ends at the highest
1662  * module symbol.  Start addresses are rounded down to the nearest page.  End
1663  * addresses are rounded up to the nearest page.  An extra page is added to the
1664  * highest kernel symbol and highest module symbol to, hopefully, encompass that
1665  * symbol too.  Because it contains only code sections, the resulting kcore is
1666  * unusual.  One significant peculiarity is that the mapping (start -> pgoff)
1667  * is not the same for the kernel map and the modules map.  That happens because
1668  * the data is copied adjacently whereas the original kcore has gaps.  Finally,
1669  * kallsyms and modules files are compared with their copies to check that
1670  * modules have not been loaded or unloaded while the copies were taking place.
1671  *
1672  * Return: %0 on success, %-1 on failure.
1673  */
1674 int kcore_copy(const char *from_dir, const char *to_dir)
1675 {
1676         struct kcore kcore;
1677         struct kcore extract;
1678         size_t count = 2;
1679         int idx = 0, err = -1;
1680         off_t offset = page_size, sz, modules_offset = 0;
1681         struct kcore_copy_info kci = { .stext = 0, };
1682         char kcore_filename[PATH_MAX];
1683         char extract_filename[PATH_MAX];
1684
1685         if (kcore_copy__copy_file(from_dir, to_dir, "kallsyms"))
1686                 return -1;
1687
1688         if (kcore_copy__copy_file(from_dir, to_dir, "modules"))
1689                 goto out_unlink_kallsyms;
1690
1691         scnprintf(kcore_filename, PATH_MAX, "%s/kcore", from_dir);
1692         scnprintf(extract_filename, PATH_MAX, "%s/kcore", to_dir);
1693
1694         if (kcore__open(&kcore, kcore_filename))
1695                 goto out_unlink_modules;
1696
1697         if (kcore_copy__calc_maps(&kci, from_dir, kcore.elf))
1698                 goto out_kcore_close;
1699
1700         if (kcore__init(&extract, extract_filename, kcore.elfclass, false))
1701                 goto out_kcore_close;
1702
1703         if (!kci.modules_map.addr)
1704                 count -= 1;
1705
1706         if (kcore__copy_hdr(&kcore, &extract, count))
1707                 goto out_extract_close;
1708
1709         if (kcore__add_phdr(&extract, idx++, offset, kci.kernel_map.addr,
1710                             kci.kernel_map.len))
1711                 goto out_extract_close;
1712
1713         if (kci.modules_map.addr) {
1714                 modules_offset = offset + kci.kernel_map.len;
1715                 if (kcore__add_phdr(&extract, idx, modules_offset,
1716                                     kci.modules_map.addr, kci.modules_map.len))
1717                         goto out_extract_close;
1718         }
1719
1720         sz = kcore__write(&extract);
1721         if (sz < 0 || sz > offset)
1722                 goto out_extract_close;
1723
1724         if (copy_bytes(kcore.fd, kci.kernel_map.offset, extract.fd, offset,
1725                        kci.kernel_map.len))
1726                 goto out_extract_close;
1727
1728         if (modules_offset && copy_bytes(kcore.fd, kci.modules_map.offset,
1729                                          extract.fd, modules_offset,
1730                                          kci.modules_map.len))
1731                 goto out_extract_close;
1732
1733         if (kcore_copy__compare_file(from_dir, to_dir, "modules"))
1734                 goto out_extract_close;
1735
1736         if (kcore_copy__compare_file(from_dir, to_dir, "kallsyms"))
1737                 goto out_extract_close;
1738
1739         err = 0;
1740
1741 out_extract_close:
1742         kcore__close(&extract);
1743         if (err)
1744                 unlink(extract_filename);
1745 out_kcore_close:
1746         kcore__close(&kcore);
1747 out_unlink_modules:
1748         if (err)
1749                 kcore_copy__unlink(to_dir, "modules");
1750 out_unlink_kallsyms:
1751         if (err)
1752                 kcore_copy__unlink(to_dir, "kallsyms");
1753
1754         return err;
1755 }
1756
1757 int kcore_extract__create(struct kcore_extract *kce)
1758 {
1759         struct kcore kcore;
1760         struct kcore extract;
1761         size_t count = 1;
1762         int idx = 0, err = -1;
1763         off_t offset = page_size, sz;
1764
1765         if (kcore__open(&kcore, kce->kcore_filename))
1766                 return -1;
1767
1768         strcpy(kce->extract_filename, PERF_KCORE_EXTRACT);
1769         if (kcore__init(&extract, kce->extract_filename, kcore.elfclass, true))
1770                 goto out_kcore_close;
1771
1772         if (kcore__copy_hdr(&kcore, &extract, count))
1773                 goto out_extract_close;
1774
1775         if (kcore__add_phdr(&extract, idx, offset, kce->addr, kce->len))
1776                 goto out_extract_close;
1777
1778         sz = kcore__write(&extract);
1779         if (sz < 0 || sz > offset)
1780                 goto out_extract_close;
1781
1782         if (copy_bytes(kcore.fd, kce->offs, extract.fd, offset, kce->len))
1783                 goto out_extract_close;
1784
1785         err = 0;
1786
1787 out_extract_close:
1788         kcore__close(&extract);
1789         if (err)
1790                 unlink(kce->extract_filename);
1791 out_kcore_close:
1792         kcore__close(&kcore);
1793
1794         return err;
1795 }
1796
1797 void kcore_extract__delete(struct kcore_extract *kce)
1798 {
1799         unlink(kce->extract_filename);
1800 }
1801
1802 #ifdef HAVE_GELF_GETNOTE_SUPPORT
1803 /**
1804  * populate_sdt_note : Parse raw data and identify SDT note
1805  * @elf: elf of the opened file
1806  * @data: raw data of a section with description offset applied
1807  * @len: note description size
1808  * @type: type of the note
1809  * @sdt_notes: List to add the SDT note
1810  *
1811  * Responsible for parsing the @data in section .note.stapsdt in @elf and
1812  * if its an SDT note, it appends to @sdt_notes list.
1813  */
1814 static int populate_sdt_note(Elf **elf, const char *data, size_t len,
1815                              struct list_head *sdt_notes)
1816 {
1817         const char *provider, *name;
1818         struct sdt_note *tmp = NULL;
1819         GElf_Ehdr ehdr;
1820         GElf_Addr base_off = 0;
1821         GElf_Shdr shdr;
1822         int ret = -EINVAL;
1823
1824         union {
1825                 Elf64_Addr a64[NR_ADDR];
1826                 Elf32_Addr a32[NR_ADDR];
1827         } buf;
1828
1829         Elf_Data dst = {
1830                 .d_buf = &buf, .d_type = ELF_T_ADDR, .d_version = EV_CURRENT,
1831                 .d_size = gelf_fsize((*elf), ELF_T_ADDR, NR_ADDR, EV_CURRENT),
1832                 .d_off = 0, .d_align = 0
1833         };
1834         Elf_Data src = {
1835                 .d_buf = (void *) data, .d_type = ELF_T_ADDR,
1836                 .d_version = EV_CURRENT, .d_size = dst.d_size, .d_off = 0,
1837                 .d_align = 0
1838         };
1839
1840         tmp = (struct sdt_note *)calloc(1, sizeof(struct sdt_note));
1841         if (!tmp) {
1842                 ret = -ENOMEM;
1843                 goto out_err;
1844         }
1845
1846         INIT_LIST_HEAD(&tmp->note_list);
1847
1848         if (len < dst.d_size + 3)
1849                 goto out_free_note;
1850
1851         /* Translation from file representation to memory representation */
1852         if (gelf_xlatetom(*elf, &dst, &src,
1853                           elf_getident(*elf, NULL)[EI_DATA]) == NULL) {
1854                 pr_err("gelf_xlatetom : %s\n", elf_errmsg(-1));
1855                 goto out_free_note;
1856         }
1857
1858         /* Populate the fields of sdt_note */
1859         provider = data + dst.d_size;
1860
1861         name = (const char *)memchr(provider, '\0', data + len - provider);
1862         if (name++ == NULL)
1863                 goto out_free_note;
1864
1865         tmp->provider = strdup(provider);
1866         if (!tmp->provider) {
1867                 ret = -ENOMEM;
1868                 goto out_free_note;
1869         }
1870         tmp->name = strdup(name);
1871         if (!tmp->name) {
1872                 ret = -ENOMEM;
1873                 goto out_free_prov;
1874         }
1875
1876         if (gelf_getclass(*elf) == ELFCLASS32) {
1877                 memcpy(&tmp->addr, &buf, 3 * sizeof(Elf32_Addr));
1878                 tmp->bit32 = true;
1879         } else {
1880                 memcpy(&tmp->addr, &buf, 3 * sizeof(Elf64_Addr));
1881                 tmp->bit32 = false;
1882         }
1883
1884         if (!gelf_getehdr(*elf, &ehdr)) {
1885                 pr_debug("%s : cannot get elf header.\n", __func__);
1886                 ret = -EBADF;
1887                 goto out_free_name;
1888         }
1889
1890         /* Adjust the prelink effect :
1891          * Find out the .stapsdt.base section.
1892          * This scn will help us to handle prelinking (if present).
1893          * Compare the retrieved file offset of the base section with the
1894          * base address in the description of the SDT note. If its different,
1895          * then accordingly, adjust the note location.
1896          */
1897         if (elf_section_by_name(*elf, &ehdr, &shdr, SDT_BASE_SCN, NULL)) {
1898                 base_off = shdr.sh_offset;
1899                 if (base_off) {
1900                         if (tmp->bit32)
1901                                 tmp->addr.a32[0] = tmp->addr.a32[0] + base_off -
1902                                         tmp->addr.a32[1];
1903                         else
1904                                 tmp->addr.a64[0] = tmp->addr.a64[0] + base_off -
1905                                         tmp->addr.a64[1];
1906                 }
1907         }
1908
1909         list_add_tail(&tmp->note_list, sdt_notes);
1910         return 0;
1911
1912 out_free_name:
1913         free(tmp->name);
1914 out_free_prov:
1915         free(tmp->provider);
1916 out_free_note:
1917         free(tmp);
1918 out_err:
1919         return ret;
1920 }
1921
1922 /**
1923  * construct_sdt_notes_list : constructs a list of SDT notes
1924  * @elf : elf to look into
1925  * @sdt_notes : empty list_head
1926  *
1927  * Scans the sections in 'elf' for the section
1928  * .note.stapsdt. It, then calls populate_sdt_note to find
1929  * out the SDT events and populates the 'sdt_notes'.
1930  */
1931 static int construct_sdt_notes_list(Elf *elf, struct list_head *sdt_notes)
1932 {
1933         GElf_Ehdr ehdr;
1934         Elf_Scn *scn = NULL;
1935         Elf_Data *data;
1936         GElf_Shdr shdr;
1937         size_t shstrndx, next;
1938         GElf_Nhdr nhdr;
1939         size_t name_off, desc_off, offset;
1940         int ret = 0;
1941
1942         if (gelf_getehdr(elf, &ehdr) == NULL) {
1943                 ret = -EBADF;
1944                 goto out_ret;
1945         }
1946         if (elf_getshdrstrndx(elf, &shstrndx) != 0) {
1947                 ret = -EBADF;
1948                 goto out_ret;
1949         }
1950
1951         /* Look for the required section */
1952         scn = elf_section_by_name(elf, &ehdr, &shdr, SDT_NOTE_SCN, NULL);
1953         if (!scn) {
1954                 ret = -ENOENT;
1955                 goto out_ret;
1956         }
1957
1958         if ((shdr.sh_type != SHT_NOTE) || (shdr.sh_flags & SHF_ALLOC)) {
1959                 ret = -ENOENT;
1960                 goto out_ret;
1961         }
1962
1963         data = elf_getdata(scn, NULL);
1964
1965         /* Get the SDT notes */
1966         for (offset = 0; (next = gelf_getnote(data, offset, &nhdr, &name_off,
1967                                               &desc_off)) > 0; offset = next) {
1968                 if (nhdr.n_namesz == sizeof(SDT_NOTE_NAME) &&
1969                     !memcmp(data->d_buf + name_off, SDT_NOTE_NAME,
1970                             sizeof(SDT_NOTE_NAME))) {
1971                         /* Check the type of the note */
1972                         if (nhdr.n_type != SDT_NOTE_TYPE)
1973                                 goto out_ret;
1974
1975                         ret = populate_sdt_note(&elf, ((data->d_buf) + desc_off),
1976                                                 nhdr.n_descsz, sdt_notes);
1977                         if (ret < 0)
1978                                 goto out_ret;
1979                 }
1980         }
1981         if (list_empty(sdt_notes))
1982                 ret = -ENOENT;
1983
1984 out_ret:
1985         return ret;
1986 }
1987
1988 /**
1989  * get_sdt_note_list : Wrapper to construct a list of sdt notes
1990  * @head : empty list_head
1991  * @target : file to find SDT notes from
1992  *
1993  * This opens the file, initializes
1994  * the ELF and then calls construct_sdt_notes_list.
1995  */
1996 int get_sdt_note_list(struct list_head *head, const char *target)
1997 {
1998         Elf *elf;
1999         int fd, ret;
2000
2001         fd = open(target, O_RDONLY);
2002         if (fd < 0)
2003                 return -EBADF;
2004
2005         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
2006         if (!elf) {
2007                 ret = -EBADF;
2008                 goto out_close;
2009         }
2010         ret = construct_sdt_notes_list(elf, head);
2011         elf_end(elf);
2012 out_close:
2013         close(fd);
2014         return ret;
2015 }
2016
2017 /**
2018  * cleanup_sdt_note_list : free the sdt notes' list
2019  * @sdt_notes: sdt notes' list
2020  *
2021  * Free up the SDT notes in @sdt_notes.
2022  * Returns the number of SDT notes free'd.
2023  */
2024 int cleanup_sdt_note_list(struct list_head *sdt_notes)
2025 {
2026         struct sdt_note *tmp, *pos;
2027         int nr_free = 0;
2028
2029         list_for_each_entry_safe(pos, tmp, sdt_notes, note_list) {
2030                 list_del(&pos->note_list);
2031                 free(pos->name);
2032                 free(pos->provider);
2033                 free(pos);
2034                 nr_free++;
2035         }
2036         return nr_free;
2037 }
2038
2039 /**
2040  * sdt_notes__get_count: Counts the number of sdt events
2041  * @start: list_head to sdt_notes list
2042  *
2043  * Returns the number of SDT notes in a list
2044  */
2045 int sdt_notes__get_count(struct list_head *start)
2046 {
2047         struct sdt_note *sdt_ptr;
2048         int count = 0;
2049
2050         list_for_each_entry(sdt_ptr, start, note_list)
2051                 count++;
2052         return count;
2053 }
2054 #endif
2055
2056 void symbol__elf_init(void)
2057 {
2058         elf_version(EV_CURRENT);
2059 }