tools/perf/util/symbol.c

   1 #include "util.h"
   2 #include "../perf.h"
   3 #include "string.h"
   4 #include "symbol.h"
   5
   6 #include <libelf.h>
   7 #include <gelf.h>
   8 #include <elf.h>
   9
  10 const char *sym_hist_filter;
  11
  12 static struct symbol *symbol__new(uint64_t start, uint64_t len,
  13                                   const char *name, unsigned int priv_size,
  14                                   uint64_t obj_start, int verbose)
  15 {
  16         size_t namelen = strlen(name) + 1;
  17         struct symbol *self = calloc(1, priv_size + sizeof(*self) + namelen);
  18
  19         if (!self)
  20                 return NULL;
  21
  22         if (verbose >= 2)
  23                 printf("new symbol: %016Lx [%08lx]: %s, hist: %p, obj_start: %p\n",
  24                         (__u64)start, (unsigned long)len, name, self->hist, (void *)(unsigned long)obj_start);
  25
  26         self->obj_start= obj_start;
  27         self->hist = NULL;
  28         self->hist_sum = 0;
  29
  30         if (sym_hist_filter && !strcmp(name, sym_hist_filter))
  31                 self->hist = calloc(sizeof(__u64), len);
  32
  33         if (priv_size) {
  34                 memset(self, 0, priv_size);
  35                 self = ((void *)self) + priv_size;
  36         }
  37         self->start = start;
  38         self->end   = start + len - 1;
  39         memcpy(self->name, name, namelen);
  40
  41         return self;
  42 }
  43
  44 static void symbol__delete(struct symbol *self, unsigned int priv_size)
  45 {
  46         free(((void *)self) - priv_size);
  47 }
  48
  49 static size_t symbol__fprintf(struct symbol *self, FILE *fp)
  50 {
  51         return fprintf(fp, " %llx-%llx %s\n",
  52                        self->start, self->end, self->name);
  53 }
  54
  55 struct dso *dso__new(const char *name, unsigned int sym_priv_size)
  56 {
  57         struct dso *self = malloc(sizeof(*self) + strlen(name) + 1);
  58
  59         if (self != NULL) {
  60                 strcpy(self->name, name);
  61                 self->syms = RB_ROOT;
  62                 self->sym_priv_size = sym_priv_size;
  63                 self->find_symbol = dso__find_symbol;
  64         }
  65
  66         return self;
  67 }
  68
  69 static void dso__delete_symbols(struct dso *self)
  70 {
  71         struct symbol *pos;
  72         struct rb_node *next = rb_first(&self->syms);
  73
  74         while (next) {
  75                 pos = rb_entry(next, struct symbol, rb_node);
  76                 next = rb_next(&pos->rb_node);
  77                 rb_erase(&pos->rb_node, &self->syms);
  78                 symbol__delete(pos, self->sym_priv_size);
  79         }
  80 }
  81
  82 void dso__delete(struct dso *self)
  83 {
  84         dso__delete_symbols(self);
  85         free(self);
  86 }
  87
  88 static void dso__insert_symbol(struct dso *self, struct symbol *sym)
  89 {
  90         struct rb_node **p = &self->syms.rb_node;
  91         struct rb_node *parent = NULL;
  92         const uint64_t ip = sym->start;
  93         struct symbol *s;
  94
  95         while (*p != NULL) {
  96                 parent = *p;
  97                 s = rb_entry(parent, struct symbol, rb_node);
  98                 if (ip < s->start)
  99                         p = &(*p)->rb_left;
 100                 else
 101                         p = &(*p)->rb_right;
 102         }
 103         rb_link_node(&sym->rb_node, parent, p);
 104         rb_insert_color(&sym->rb_node, &self->syms);
 105 }
 106
 107 struct symbol *dso__find_symbol(struct dso *self, uint64_t ip)
 108 {
 109         struct rb_node *n;
 110
 111         if (self == NULL)
 112                 return NULL;
 113
 114         n = self->syms.rb_node;
 115
 116         while (n) {
 117                 struct symbol *s = rb_entry(n, struct symbol, rb_node);
 118
 119                 if (ip < s->start)
 120                         n = n->rb_left;
 121                 else if (ip > s->end)
 122                         n = n->rb_right;
 123                 else
 124                         return s;
 125         }
 126
 127         return NULL;
 128 }
 129
 130 size_t dso__fprintf(struct dso *self, FILE *fp)
 131 {
 132         size_t ret = fprintf(fp, "dso: %s\n", self->name);
 133
 134         struct rb_node *nd;
 135         for (nd = rb_first(&self->syms); nd; nd = rb_next(nd)) {
 136                 struct symbol *pos = rb_entry(nd, struct symbol, rb_node);
 137                 ret += symbol__fprintf(pos, fp);
 138         }
 139
 140         return ret;
 141 }
 142
 143 static int dso__load_kallsyms(struct dso *self, symbol_filter_t filter, int verbose)
 144 {
 145         struct rb_node *nd, *prevnd;
 146         char *line = NULL;
 147         size_t n;
 148         FILE *file = fopen("/proc/kallsyms", "r");
 149
 150         if (file == NULL)
 151                 goto out_failure;
 152
 153         while (!feof(file)) {
 154                 __u64 start;
 155                 struct symbol *sym;
 156                 int line_len, len;
 157                 char symbol_type;
 158
 159                 line_len = getline(&line, &n, file);
 160                 if (line_len < 0)
 161                         break;
 162
 163                 if (!line)
 164                         goto out_failure;
 165
 166                 line[--line_len] = '\0'; /* \n */
 167
 168                 len = hex2u64(line, &start);
 169
 170                 len++;
 171                 if (len + 2 >= line_len)
 172                         continue;
 173
 174                 symbol_type = toupper(line[len]);
 175                 /*
 176                  * We're interested only in code ('T'ext)
 177                  */
 178                 if (symbol_type != 'T' && symbol_type != 'W')
 179                         continue;
 180                 /*
 181                  * Well fix up the end later, when we have all sorted.
 182                  */
 183                 sym = symbol__new(start, 0xdead, line + len + 2,
 184                                   self->sym_priv_size, 0, verbose);
 185
 186                 if (sym == NULL)
 187                         goto out_delete_line;
 188
 189                 if (filter && filter(self, sym))
 190                         symbol__delete(sym, self->sym_priv_size);
 191                 else
 192                         dso__insert_symbol(self, sym);
 193         }
 194
 195         /*
 196          * Now that we have all sorted out, just set the ->end of all
 197          * symbols
 198          */
 199         prevnd = rb_first(&self->syms);
 200
 201         if (prevnd == NULL)
 202                 goto out_delete_line;
 203
 204         for (nd = rb_next(prevnd); nd; nd = rb_next(nd)) {
 205                 struct symbol *prev = rb_entry(prevnd, struct symbol, rb_node),
 206                               *curr = rb_entry(nd, struct symbol, rb_node);
 207
 208                 prev->end = curr->start - 1;
 209                 prevnd = nd;
 210         }
 211
 212         free(line);
 213         fclose(file);
 214
 215         return 0;
 216
 217 out_delete_line:
 218         free(line);
 219 out_failure:
 220         return -1;
 221 }
 222
 223 /**
 224  * elf_symtab__for_each_symbol - iterate thru all the symbols
 225  *
 226  * @self: struct elf_symtab instance to iterate
 227  * @index: uint32_t index
 228  * @sym: GElf_Sym iterator
 229  */
 230 #define elf_symtab__for_each_symbol(syms, nr_syms, index, sym) \
 231         for (index = 0, gelf_getsym(syms, index, &sym);\
 232              index < nr_syms; \
 233              index++, gelf_getsym(syms, index, &sym))
 234
 235 static inline uint8_t elf_sym__type(const GElf_Sym *sym)
 236 {
 237         return GELF_ST_TYPE(sym->st_info);
 238 }
 239
 240 static inline int elf_sym__is_function(const GElf_Sym *sym)
 241 {
 242         return elf_sym__type(sym) == STT_FUNC &&
 243                sym->st_name != 0 &&
 244                sym->st_shndx != SHN_UNDEF &&
 245                sym->st_size != 0;
 246 }
 247
 248 static inline const char *elf_sym__name(const GElf_Sym *sym,
 249                                         const Elf_Data *symstrs)
 250 {
 251         return symstrs->d_buf + sym->st_name;
 252 }
 253
 254 static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
 255                                     GElf_Shdr *shp, const char *name,
 256                                     size_t *index)
 257 {
 258         Elf_Scn *sec = NULL;
 259         size_t cnt = 1;
 260
 261         while ((sec = elf_nextscn(elf, sec)) != NULL) {
 262                 char *str;
 263
 264                 gelf_getshdr(sec, shp);
 265                 str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
 266                 if (!strcmp(name, str)) {
 267                         if (index)
 268                                 *index = cnt;
 269                         break;
 270                 }
 271                 ++cnt;
 272         }
 273
 274         return sec;
 275 }
 276
 277 #define elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_entries) \
 278         for (idx = 0, pos = gelf_getrel(reldata, 0, &pos_mem); \
 279              idx < nr_entries; \
 280              ++idx, pos = gelf_getrel(reldata, idx, &pos_mem))
 281
 282 #define elf_section__for_each_rela(reldata, pos, pos_mem, idx, nr_entries) \
 283         for (idx = 0, pos = gelf_getrela(reldata, 0, &pos_mem); \
 284              idx < nr_entries; \
 285              ++idx, pos = gelf_getrela(reldata, idx, &pos_mem))
 286
 287 static int dso__synthesize_plt_symbols(struct  dso *self, Elf *elf,
 288                                        GElf_Ehdr *ehdr, Elf_Scn *scn_dynsym,
 289                                        GElf_Shdr *shdr_dynsym,
 290                                        size_t dynsym_idx, int verbose)
 291 {
 292         uint32_t nr_rel_entries, idx;
 293         GElf_Sym sym;
 294         __u64 plt_offset;
 295         GElf_Shdr shdr_plt;
 296         struct symbol *f;
 297         GElf_Shdr shdr_rel_plt;
 298         Elf_Data *reldata, *syms, *symstrs;
 299         Elf_Scn *scn_plt_rel, *scn_symstrs;
 300         char sympltname[1024];
 301         int nr = 0, symidx;
 302
 303         scn_plt_rel = elf_section_by_name(elf, ehdr, &shdr_rel_plt,
 304                                           ".rela.plt", NULL);
 305         if (scn_plt_rel == NULL) {
 306                 scn_plt_rel = elf_section_by_name(elf, ehdr, &shdr_rel_plt,
 307                                                   ".rel.plt", NULL);
 308                 if (scn_plt_rel == NULL)
 309                         return 0;
 310         }
 311
 312         if (shdr_rel_plt.sh_link != dynsym_idx)
 313                 return 0;
 314
 315         if (elf_section_by_name(elf, ehdr, &shdr_plt, ".plt", NULL) == NULL)
 316                 return 0;
 317
 318         /*
 319          * Fetch the relocation section to find the indexes to the GOT
 320          * and the symbols in the .dynsym they refer to.
 321          */
 322         reldata = elf_getdata(scn_plt_rel, NULL);
 323         if (reldata == NULL)
 324                 return -1;
 325
 326         syms = elf_getdata(scn_dynsym, NULL);
 327         if (syms == NULL)
 328                 return -1;
 329
 330         scn_symstrs = elf_getscn(elf, shdr_dynsym->sh_link);
 331         if (scn_symstrs == NULL)
 332                 return -1;
 333
 334         symstrs = elf_getdata(scn_symstrs, NULL);
 335         if (symstrs == NULL)
 336                 return -1;
 337
 338         nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize;
 339         plt_offset = shdr_plt.sh_offset;
 340
 341         if (shdr_rel_plt.sh_type == SHT_RELA) {
 342                 GElf_Rela pos_mem, *pos;
 343
 344                 elf_section__for_each_rela(reldata, pos, pos_mem, idx,
 345                                            nr_rel_entries) {
 346                         symidx = GELF_R_SYM(pos->r_info);
 347                         plt_offset += shdr_plt.sh_entsize;
 348                         gelf_getsym(syms, symidx, &sym);
 349                         snprintf(sympltname, sizeof(sympltname),
 350                                  "%s@plt", elf_sym__name(&sym, symstrs));
 351
 352                         f = symbol__new(plt_offset, shdr_plt.sh_entsize,
 353                                         sympltname, self->sym_priv_size, 0, verbose);
 354                         if (!f)
 355                                 return -1;
 356
 357                         dso__insert_symbol(self, f);
 358                         ++nr;
 359                 }
 360         } else if (shdr_rel_plt.sh_type == SHT_REL) {
 361                 GElf_Rel pos_mem, *pos;
 362                 elf_section__for_each_rel(reldata, pos, pos_mem, idx,
 363                                           nr_rel_entries) {
 364                         symidx = GELF_R_SYM(pos->r_info);
 365                         plt_offset += shdr_plt.sh_entsize;
 366                         gelf_getsym(syms, symidx, &sym);
 367                         snprintf(sympltname, sizeof(sympltname),
 368                                  "%s@plt", elf_sym__name(&sym, symstrs));
 369
 370                         f = symbol__new(plt_offset, shdr_plt.sh_entsize,
 371                                         sympltname, self->sym_priv_size, 0, verbose);
 372                         if (!f)
 373                                 return -1;
 374
 375                         dso__insert_symbol(self, f);
 376                         ++nr;
 377                 }
 378         } else {
 379                 /*
 380                  * TODO: There are still one more shdr_rel_plt.sh_type
 381                  * I have to investigate, but probably should be ignored.
 382                  */
 383         }
 384
 385         return nr;
 386 }
 387
 388 static int dso__load_sym(struct dso *self, int fd, const char *name,
 389                          symbol_filter_t filter, int verbose)
 390 {
 391         Elf_Data *symstrs;
 392         uint32_t nr_syms;
 393         int err = -1;
 394         uint32_t index;
 395         GElf_Ehdr ehdr;
 396         GElf_Shdr shdr;
 397         Elf_Data *syms;
 398         GElf_Sym sym;
 399         Elf_Scn *sec, *sec_dynsym;
 400         Elf *elf;
 401         size_t dynsym_idx;
 402         int nr = 0;
 403
 404         elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
 405         if (elf == NULL) {
 406                 if (verbose)
 407                         fprintf(stderr, "%s: cannot read %s ELF file.\n",
 408                                 __func__, name);
 409                 goto out_close;
 410         }
 411
 412         if (gelf_getehdr(elf, &ehdr) == NULL) {
 413                 if (verbose)
 414                         fprintf(stderr, "%s: cannot get elf header.\n", __func__);
 415                 goto out_elf_end;
 416         }
 417
 418         /*
 419          * We need to check if we have a .dynsym, so that we can handle the
 420          * .plt, synthesizing its symbols, that aren't on the symtabs (be it
 421          * .dynsym or .symtab)
 422          */
 423         sec_dynsym = elf_section_by_name(elf, &ehdr, &shdr,
 424                                          ".dynsym", &dynsym_idx);
 425         if (sec_dynsym != NULL) {
 426                 nr = dso__synthesize_plt_symbols(self, elf, &ehdr,
 427                                                  sec_dynsym, &shdr,
 428                                                  dynsym_idx, verbose);
 429                 if (nr < 0)
 430                         goto out_elf_end;
 431         }
 432
 433         /*
 434          * But if we have a full .symtab (that is a superset of .dynsym) we
 435          * should add the symbols not in the .dynsyn
 436          */
 437         sec = elf_section_by_name(elf, &ehdr, &shdr, ".symtab", NULL);
 438         if (sec == NULL) {
 439                 if (sec_dynsym == NULL)
 440                         goto out_elf_end;
 441
 442                 sec = sec_dynsym;
 443                 gelf_getshdr(sec, &shdr);
 444         }
 445
 446         syms = elf_getdata(sec, NULL);
 447         if (syms == NULL)
 448                 goto out_elf_end;
 449
 450         sec = elf_getscn(elf, shdr.sh_link);
 451         if (sec == NULL)
 452                 goto out_elf_end;
 453
 454         symstrs = elf_getdata(sec, NULL);
 455         if (symstrs == NULL)
 456                 goto out_elf_end;
 457
 458         nr_syms = shdr.sh_size / shdr.sh_entsize;
 459
 460         elf_symtab__for_each_symbol(syms, nr_syms, index, sym) {
 461                 struct symbol *f;
 462                 uint64_t obj_start;
 463
 464                 if (!elf_sym__is_function(&sym))
 465                         continue;
 466
 467                 sec = elf_getscn(elf, sym.st_shndx);
 468                 if (!sec)
 469                         goto out_elf_end;
 470
 471                 gelf_getshdr(sec, &shdr);
 472                 obj_start = sym.st_value;
 473
 474                 sym.st_value -= shdr.sh_addr - shdr.sh_offset;
 475
 476                 f = symbol__new(sym.st_value, sym.st_size,
 477                                 elf_sym__name(&sym, symstrs),
 478                                 self->sym_priv_size, obj_start, verbose);
 479                 if (!f)
 480                         goto out_elf_end;
 481
 482                 if (filter && filter(self, f))
 483                         symbol__delete(f, self->sym_priv_size);
 484                 else {
 485                         dso__insert_symbol(self, f);
 486                         nr++;
 487                 }
 488         }
 489
 490         err = nr;
 491 out_elf_end:
 492         elf_end(elf);
 493 out_close:
 494         return err;
 495 }
 496
 497 int dso__load(struct dso *self, symbol_filter_t filter, int verbose)
 498 {
 499         int size = strlen(self->name) + sizeof("/usr/lib/debug%s.debug");
 500         char *name = malloc(size);
 501         int variant = 0;
 502         int ret = -1;
 503         int fd;
 504
 505         if (!name)
 506                 return -1;
 507
 508 more:
 509         do {
 510                 switch (variant) {
 511                 case 0: /* Fedora */
 512                         snprintf(name, size, "/usr/lib/debug%s.debug", self->name);
 513                         break;
 514                 case 1: /* Ubuntu */
 515                         snprintf(name, size, "/usr/lib/debug%s", self->name);
 516                         break;
 517                 case 2: /* Sane people */
 518                         snprintf(name, size, "%s", self->name);
 519                         break;
 520
 521                 default:
 522                         goto out;
 523                 }
 524                 variant++;
 525
 526                 fd = open(name, O_RDONLY);
 527         } while (fd < 0);
 528
 529         ret = dso__load_sym(self, fd, name, filter, verbose);
 530         close(fd);
 531
 532         /*
 533          * Some people seem to have debuginfo files _WITHOUT_ debug info!?!?
 534          */
 535         if (!ret)
 536                 goto more;
 537
 538 out:
 539         free(name);
 540         return ret;
 541 }
 542
 543 static int dso__load_vmlinux(struct dso *self, const char *vmlinux,
 544                              symbol_filter_t filter, int verbose)
 545 {
 546         int err, fd = open(vmlinux, O_RDONLY);
 547
 548         if (fd < 0)
 549                 return -1;
 550
 551         err = dso__load_sym(self, fd, vmlinux, filter, verbose);
 552         close(fd);
 553
 554         return err;
 555 }
 556
 557 int dso__load_kernel(struct dso *self, const char *vmlinux,
 558                      symbol_filter_t filter, int verbose)
 559 {
 560         int err = -1;
 561
 562         if (vmlinux)
 563                 err = dso__load_vmlinux(self, vmlinux, filter, verbose);
 564
 565         if (err)
 566                 err = dso__load_kallsyms(self, filter, verbose);
 567
 568         return err;
 569 }
 570
 571 void symbol__init(void)
 572 {
 573         elf_version(EV_CURRENT);
 574 }