SAFE public projects git trees. - safe/jmp/linux-2.6/blob - Documentation/perf_counter/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 static struct symbol *symbol__new(uint64_t start, uint64_t len,
  11                                   const char *name, unsigned int priv_size)
  12 {
  13         size_t namelen = strlen(name) + 1;
  14         struct symbol *self = malloc(priv_size + sizeof(*self) + namelen);
  15
  16         if (self != NULL) {
  17                 if (priv_size) {
  18                         memset(self, 0, priv_size);
  19                         self = ((void *)self) + priv_size;
  20                 }
  21                 self->start = start;
  22                 self->end   = start + len - 1;
  23                 memcpy(self->name, name, namelen);
  24         }
  25
  26         return self;
  27 }
  28
  29 static void symbol__delete(struct symbol *self, unsigned int priv_size)
  30 {
  31         free(((void *)self) - priv_size);
  32 }
  33
  34 static size_t symbol__fprintf(struct symbol *self, FILE *fp)
  35 {
  36         return fprintf(fp, " %llx-%llx %s\n",
  37                        self->start, self->end, self->name);
  38 }
  39
  40 struct dso *dso__new(const char *name, unsigned int sym_priv_size)
  41 {
  42         struct dso *self = malloc(sizeof(*self) + strlen(name) + 1);
  43
  44         if (self != NULL) {
  45                 strcpy(self->name, name);
  46                 self->syms = RB_ROOT;
  47                 self->sym_priv_size = sym_priv_size;
  48         }
  49
  50         return self;
  51 }
  52
  53 static void dso__delete_symbols(struct dso *self)
  54 {
  55         struct symbol *pos;
  56         struct rb_node *next = rb_first(&self->syms);
  57
  58         while (next) {
  59                 pos = rb_entry(next, struct symbol, rb_node);
  60                 next = rb_next(&pos->rb_node);
  61                 rb_erase(&pos->rb_node, &self->syms);
  62                 symbol__delete(pos, self->sym_priv_size);
  63         }
  64 }
  65
  66 void dso__delete(struct dso *self)
  67 {
  68         dso__delete_symbols(self);
  69         free(self);
  70 }
  71
  72 static void dso__insert_symbol(struct dso *self, struct symbol *sym)
  73 {
  74         struct rb_node **p = &self->syms.rb_node;
  75         struct rb_node *parent = NULL;
  76         const uint64_t ip = sym->start;
  77         struct symbol *s;
  78
  79         while (*p != NULL) {
  80                 parent = *p;
  81                 s = rb_entry(parent, struct symbol, rb_node);
  82                 if (ip < s->start)
  83                         p = &(*p)->rb_left;
  84                 else
  85                         p = &(*p)->rb_right;
  86         }
  87         rb_link_node(&sym->rb_node, parent, p);
  88         rb_insert_color(&sym->rb_node, &self->syms);
  89 }
  90
  91 struct symbol *dso__find_symbol(struct dso *self, uint64_t ip)
  92 {
  93         struct rb_node *n;
  94
  95         if (self == NULL)
  96                 return NULL;
  97
  98         n = self->syms.rb_node;
  99
 100         while (n) {
 101                 struct symbol *s = rb_entry(n, struct symbol, rb_node);
 102
 103                 if (ip < s->start)
 104                         n = n->rb_left;
 105                 else if (ip > s->end)
 106                         n = n->rb_right;
 107                 else
 108                         return s;
 109         }
 110
 111         return NULL;
 112 }
 113
 114 size_t dso__fprintf(struct dso *self, FILE *fp)
 115 {
 116         size_t ret = fprintf(fp, "dso: %s\n", self->name);
 117
 118         struct rb_node *nd;
 119         for (nd = rb_first(&self->syms); nd; nd = rb_next(nd)) {
 120                 struct symbol *pos = rb_entry(nd, struct symbol, rb_node);
 121                 ret += symbol__fprintf(pos, fp);
 122         }
 123
 124         return ret;
 125 }
 126
 127 static int dso__load_kallsyms(struct dso *self, symbol_filter_t filter)
 128 {
 129         struct rb_node *nd, *prevnd;
 130         char *line = NULL;
 131         size_t n;
 132         FILE *file = fopen("/proc/kallsyms", "r");
 133
 134         if (file == NULL)
 135                 goto out_failure;
 136
 137         while (!feof(file)) {
 138                 __u64 start;
 139                 struct symbol *sym;
 140                 int line_len, len;
 141                 char symbol_type;
 142
 143                 line_len = getline(&line, &n, file);
 144                 if (line_len < 0)
 145                         break;
 146
 147                 if (!line)
 148                         goto out_failure;
 149
 150                 line[--line_len] = '\0'; /* \n */
 151
 152                 len = hex2u64(line, &start);
 153
 154                 len++;
 155                 if (len + 2 >= line_len)
 156                         continue;
 157
 158                 symbol_type = toupper(line[len]);
 159                 /*
 160                  * We're interested only in code ('T'ext)
 161                  */
 162                 if (symbol_type != 'T' && symbol_type != 'W')
 163                         continue;
 164                 /*
 165                  * Well fix up the end later, when we have all sorted.
 166                  */
 167                 sym = symbol__new(start, 0xdead, line + len + 2,
 168                                   self->sym_priv_size);
 169
 170                 if (sym == NULL)
 171                         goto out_delete_line;
 172
 173                 if (filter && filter(self, sym))
 174                         symbol__delete(sym, self->sym_priv_size);
 175                 else
 176                         dso__insert_symbol(self, sym);
 177         }
 178
 179         /*
 180          * Now that we have all sorted out, just set the ->end of all
 181          * symbols
 182          */
 183         prevnd = rb_first(&self->syms);
 184
 185         if (prevnd == NULL)
 186                 goto out_delete_line;
 187
 188         for (nd = rb_next(prevnd); nd; nd = rb_next(nd)) {
 189                 struct symbol *prev = rb_entry(prevnd, struct symbol, rb_node),
 190                               *curr = rb_entry(nd, struct symbol, rb_node);
 191
 192                 prev->end = curr->start - 1;
 193                 prevnd = nd;
 194         }
 195
 196         free(line);
 197         fclose(file);
 198
 199         return 0;
 200
 201 out_delete_line:
 202         free(line);
 203 out_failure:
 204         return -1;
 205 }
 206
 207 /**
 208  * elf_symtab__for_each_symbol - iterate thru all the symbols
 209  *
 210  * @self: struct elf_symtab instance to iterate
 211  * @index: uint32_t index
 212  * @sym: GElf_Sym iterator
 213  */
 214 #define elf_symtab__for_each_symbol(syms, nr_syms, index, sym) \
 215         for (index = 0, gelf_getsym(syms, index, &sym);\
 216              index < nr_syms; \
 217              index++, gelf_getsym(syms, index, &sym))
 218
 219 static inline uint8_t elf_sym__type(const GElf_Sym *sym)
 220 {
 221         return GELF_ST_TYPE(sym->st_info);
 222 }
 223
 224 static inline int elf_sym__is_function(const GElf_Sym *sym)
 225 {
 226         return elf_sym__type(sym) == STT_FUNC &&
 227                sym->st_name != 0 &&
 228                sym->st_shndx != SHN_UNDEF &&
 229                sym->st_size != 0;
 230 }
 231
 232 static inline const char *elf_sym__name(const GElf_Sym *sym,
 233                                         const Elf_Data *symstrs)
 234 {
 235         return symstrs->d_buf + sym->st_name;
 236 }
 237
 238 static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
 239                                     GElf_Shdr *shp, const char *name,
 240                                     size_t *index)
 241 {
 242         Elf_Scn *sec = NULL;
 243         size_t cnt = 1;
 244
 245         while ((sec = elf_nextscn(elf, sec)) != NULL) {
 246                 char *str;
 247
 248                 gelf_getshdr(sec, shp);
 249                 str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
 250                 if (!strcmp(name, str)) {
 251                         if (index)
 252                                 *index = cnt;
 253                         break;
 254                 }
 255                 ++cnt;
 256         }
 257
 258         return sec;
 259 }
 260
 261 #define elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_entries) \
 262         for (idx = 0, pos = gelf_getrel(reldata, 0, &pos_mem); \
 263              idx < nr_entries; \
 264              ++idx, pos = gelf_getrel(reldata, idx, &pos_mem))
 265
 266 #define elf_section__for_each_rela(reldata, pos, pos_mem, idx, nr_entries) \
 267         for (idx = 0, pos = gelf_getrela(reldata, 0, &pos_mem); \
 268              idx < nr_entries; \
 269              ++idx, pos = gelf_getrela(reldata, idx, &pos_mem))
 270
 271 static int dso__synthesize_plt_symbols(struct  dso *self, Elf *elf,
 272                                        GElf_Ehdr *ehdr, Elf_Scn *scn_dynsym,
 273                                        GElf_Shdr *shdr_dynsym,
 274                                        size_t dynsym_idx)
 275 {
 276         uint32_t nr_rel_entries, idx;
 277         GElf_Sym sym;
 278         __u64 plt_offset;
 279         GElf_Shdr shdr_plt;
 280         struct symbol *f;
 281         GElf_Shdr shdr_rel_plt;
 282         Elf_Data *reldata, *syms, *symstrs;
 283         Elf_Scn *scn_plt_rel, *scn_symstrs;
 284         char sympltname[1024];
 285         int nr = 0, symidx;
 286
 287         scn_plt_rel = elf_section_by_name(elf, ehdr, &shdr_rel_plt,
 288                                           ".rela.plt", NULL);
 289         if (scn_plt_rel == NULL) {
 290                 scn_plt_rel = elf_section_by_name(elf, ehdr, &shdr_rel_plt,
 291                                                   ".rel.plt", NULL);
 292                 if (scn_plt_rel == NULL)
 293                         return 0;
 294         }
 295
 296         if (shdr_rel_plt.sh_link != dynsym_idx)
 297                 return 0;
 298
 299         if (elf_section_by_name(elf, ehdr, &shdr_plt, ".plt", NULL) == NULL)
 300                 return 0;
 301
 302         /*
 303          * Fetch the relocation section to find the indexes to the GOT
 304          * and the symbols in the .dynsym they refer to.
 305          */
 306         reldata = elf_getdata(scn_plt_rel, NULL);
 307         if (reldata == NULL)
 308                 return -1;
 309
 310         syms = elf_getdata(scn_dynsym, NULL);
 311         if (syms == NULL)
 312                 return -1;
 313
 314         scn_symstrs = elf_getscn(elf, shdr_dynsym->sh_link);
 315         if (scn_symstrs == NULL)
 316                 return -1;
 317
 318         symstrs = elf_getdata(scn_symstrs, NULL);
 319         if (symstrs == NULL)
 320                 return -1;
 321
 322         nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize;
 323         plt_offset = shdr_plt.sh_offset;
 324
 325         if (shdr_rel_plt.sh_type == SHT_RELA) {
 326                 GElf_Rela pos_mem, *pos;
 327
 328                 elf_section__for_each_rela(reldata, pos, pos_mem, idx,
 329                                            nr_rel_entries) {
 330                         symidx = GELF_R_SYM(pos->r_info);
 331                         plt_offset += shdr_plt.sh_entsize;
 332                         gelf_getsym(syms, symidx, &sym);
 333                         snprintf(sympltname, sizeof(sympltname),
 334                                  "%s@plt", elf_sym__name(&sym, symstrs));
 335
 336                         f = symbol__new(plt_offset, shdr_plt.sh_entsize,
 337                                         sympltname, self->sym_priv_size);
 338                         if (!f)
 339                                 return -1;
 340
 341                         dso__insert_symbol(self, f);
 342                         ++nr;
 343                 }
 344         } else if (shdr_rel_plt.sh_type == SHT_REL) {
 345                 GElf_Rel pos_mem, *pos;
 346                 elf_section__for_each_rel(reldata, pos, pos_mem, idx,
 347                                           nr_rel_entries) {
 348                         symidx = GELF_R_SYM(pos->r_info);
 349                         plt_offset += shdr_plt.sh_entsize;
 350                         gelf_getsym(syms, symidx, &sym);
 351                         snprintf(sympltname, sizeof(sympltname),
 352                                  "%s@plt", elf_sym__name(&sym, symstrs));
 353
 354                         f = symbol__new(plt_offset, shdr_plt.sh_entsize,
 355                                         sympltname, self->sym_priv_size);
 356                         if (!f)
 357                                 return -1;
 358
 359                         dso__insert_symbol(self, f);
 360                         ++nr;
 361                 }
 362         } else {
 363                 /*
 364                  * TODO: There are still one more shdr_rel_plt.sh_type
 365                  * I have to investigate, but probably should be ignored.
 366                  */
 367         }
 368
 369         return nr;
 370 }
 371
 372 static int dso__load_sym(struct dso *self, int fd, const char *name,
 373                          symbol_filter_t filter)
 374 {
 375         Elf_Data *symstrs;
 376         uint32_t nr_syms;
 377         int err = -1;
 378         uint32_t index;
 379         GElf_Ehdr ehdr;
 380         GElf_Shdr shdr;
 381         Elf_Data *syms;
 382         GElf_Sym sym;
 383         Elf_Scn *sec, *sec_dynsym;
 384         Elf *elf;
 385         size_t dynsym_idx;
 386         int nr = 0;
 387
 388         elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
 389         if (elf == NULL) {
 390                 fprintf(stderr, "%s: cannot read %s ELF file.\n",
 391                         __func__, name);
 392                 goto out_close;
 393         }
 394
 395         if (gelf_getehdr(elf, &ehdr) == NULL) {
 396                 fprintf(stderr, "%s: cannot get elf header.\n", __func__);
 397                 goto out_elf_end;
 398         }
 399
 400         /*
 401          * We need to check if we have a .dynsym, so that we can handle the
 402          * .plt, synthesizing its symbols, that aren't on the symtabs (be it
 403          * .dynsym or .symtab)
 404          */
 405         sec_dynsym = elf_section_by_name(elf, &ehdr, &shdr,
 406                                          ".dynsym", &dynsym_idx);
 407         if (sec_dynsym != NULL) {
 408                 nr = dso__synthesize_plt_symbols(self, elf, &ehdr,
 409                                                  sec_dynsym, &shdr,
 410                                                  dynsym_idx);
 411                 if (nr < 0)
 412                         goto out_elf_end;
 413         }
 414
 415         /*
 416          * But if we have a full .symtab (that is a superset of .dynsym) we
 417          * should add the symbols not in the .dynsyn
 418          */
 419         sec = elf_section_by_name(elf, &ehdr, &shdr, ".symtab", NULL);
 420         if (sec == NULL) {
 421                 if (sec_dynsym == NULL)
 422                         goto out_elf_end;
 423
 424                 sec = sec_dynsym;
 425                 gelf_getshdr(sec, &shdr);
 426         }
 427
 428         syms = elf_getdata(sec, NULL);
 429         if (syms == NULL)
 430                 goto out_elf_end;
 431
 432         sec = elf_getscn(elf, shdr.sh_link);
 433         if (sec == NULL)
 434                 goto out_elf_end;
 435
 436         symstrs = elf_getdata(sec, NULL);
 437         if (symstrs == NULL)
 438                 goto out_elf_end;
 439
 440         nr_syms = shdr.sh_size / shdr.sh_entsize;
 441
 442         elf_symtab__for_each_symbol(syms, nr_syms, index, sym) {
 443                 struct symbol *f;
 444
 445                 if (!elf_sym__is_function(&sym))
 446                         continue;
 447
 448                 sec = elf_getscn(elf, sym.st_shndx);
 449                 if (!sec)
 450                         goto out_elf_end;
 451
 452                 gelf_getshdr(sec, &shdr);
 453                 sym.st_value -= shdr.sh_addr - shdr.sh_offset;
 454
 455                 f = symbol__new(sym.st_value, sym.st_size,
 456                                 elf_sym__name(&sym, symstrs),
 457                                 self->sym_priv_size);
 458                 if (!f)
 459                         goto out_elf_end;
 460
 461                 if (filter && filter(self, f))
 462                         symbol__delete(f, self->sym_priv_size);
 463                 else {
 464                         dso__insert_symbol(self, f);
 465                         nr++;
 466                 }
 467         }
 468
 469         err = nr;
 470 out_elf_end:
 471         elf_end(elf);
 472 out_close:
 473         return err;
 474 }
 475
 476 int dso__load(struct dso *self, symbol_filter_t filter)
 477 {
 478         int size = strlen(self->name) + sizeof("/usr/lib/debug%s.debug");
 479         char *name = malloc(size);
 480         int variant = 0;
 481         int ret = -1;
 482         int fd;
 483
 484         if (!name)
 485                 return -1;
 486
 487 more:
 488         do {
 489                 switch (variant) {
 490                 case 0: /* Fedora */
 491                         snprintf(name, size, "/usr/lib/debug%s.debug", self->name);
 492                         break;
 493                 case 1: /* Ubuntu */
 494                         snprintf(name, size, "/usr/lib/debug%s", self->name);
 495                         break;
 496                 case 2: /* Sane people */
 497                         snprintf(name, size, "%s", self->name);
 498                         break;
 499
 500                 default:
 501                         goto out;
 502                 }
 503                 variant++;
 504
 505                 fd = open(name, O_RDONLY);
 506         } while (fd < 0);
 507
 508         ret = dso__load_sym(self, fd, name, filter);
 509         close(fd);
 510
 511         /*
 512          * Some people seem to have debuginfo files _WITHOUT_ debug info!?!?
 513          */
 514         if (!ret)
 515                 goto more;
 516
 517 out:
 518         free(name);
 519         return ret;
 520 }
 521
 522 static int dso__load_vmlinux(struct dso *self, const char *vmlinux,
 523                              symbol_filter_t filter)
 524 {
 525         int err, fd = open(vmlinux, O_RDONLY);
 526
 527         if (fd < 0)
 528                 return -1;
 529
 530         err = dso__load_sym(self, fd, vmlinux, filter);
 531         close(fd);
 532
 533         return err;
 534 }
 535
 536 int dso__load_kernel(struct dso *self, const char *vmlinux, symbol_filter_t filter)
 537 {
 538         int err = -1;
 539
 540         if (vmlinux)
 541                 err = dso__load_vmlinux(self, vmlinux, filter);
 542
 543         if (err)
 544                 err = dso__load_kallsyms(self, filter);
 545
 546         return err;
 547 }
 548
 549 void symbol__init(void)
 550 {
 551         elf_version(EV_CURRENT);
 552 }