tools/objtool/elf.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * elf.c - ELF access library
   4  *
   5  * Adapted from kpatch (https://github.com/dynup/kpatch):
   6  * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
   7  * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
   8  */
   9
  10 #include <sys/types.h>
  11 #include <sys/stat.h>
  12 #include <fcntl.h>
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <unistd.h>
  17 #include <errno.h>
  18 #include "builtin.h"
  19
  20 #include "elf.h"
  21 #include "warn.h"
  22
  23 #define MAX_NAME_LEN 128
  24
  25 static inline u32 str_hash(const char *str)
  26 {
  27         return jhash(str, strlen(str), 0);
  28 }
  29
  30 static void rb_add(struct rb_root *tree, struct rb_node *node,
  31                    int (*cmp)(struct rb_node *, const struct rb_node *))
  32 {
  33         struct rb_node **link = &tree->rb_node;
  34         struct rb_node *parent = NULL;
  35
  36         while (*link) {
  37                 parent = *link;
  38                 if (cmp(node, parent) < 0)
  39                         link = &parent->rb_left;
  40                 else
  41                         link = &parent->rb_right;
  42         }
  43
  44         rb_link_node(node, parent, link);
  45         rb_insert_color(node, tree);
  46 }
  47
  48 static struct rb_node *rb_find_first(struct rb_root *tree, const void *key,
  49                                int (*cmp)(const void *key, const struct rb_node *))
  50 {
  51         struct rb_node *node = tree->rb_node;
  52         struct rb_node *match = NULL;
  53
  54         while (node) {
  55                 int c = cmp(key, node);
  56                 if (c <= 0) {
  57                         if (!c)
  58                                 match = node;
  59                         node = node->rb_left;
  60                 } else if (c > 0) {
  61                         node = node->rb_right;
  62                 }
  63         }
  64
  65         return match;
  66 }
  67
  68 static struct rb_node *rb_next_match(struct rb_node *node, const void *key,
  69                                     int (*cmp)(const void *key, const struct rb_node *))
  70 {
  71         node = rb_next(node);
  72         if (node && cmp(key, node))
  73                 node = NULL;
  74         return node;
  75 }
  76
  77 #define rb_for_each(tree, node, key, cmp) \
  78         for ((node) = rb_find_first((tree), (key), (cmp)); \
  79              (node); (node) = rb_next_match((node), (key), (cmp)))
  80
  81 static int symbol_to_offset(struct rb_node *a, const struct rb_node *b)
  82 {
  83         struct symbol *sa = rb_entry(a, struct symbol, node);
  84         struct symbol *sb = rb_entry(b, struct symbol, node);
  85
  86         if (sa->offset < sb->offset)
  87                 return -1;
  88         if (sa->offset > sb->offset)
  89                 return 1;
  90
  91         if (sa->len < sb->len)
  92                 return -1;
  93         if (sa->len > sb->len)
  94                 return 1;
  95
  96         sa->alias = sb;
  97
  98         return 0;
  99 }
 100
 101 static int symbol_by_offset(const void *key, const struct rb_node *node)
 102 {
 103         const struct symbol *s = rb_entry(node, struct symbol, node);
 104         const unsigned long *o = key;
 105
 106         if (*o < s->offset)
 107                 return -1;
 108         if (*o > s->offset + s->len)
 109                 return 1;
 110
 111         return 0;
 112 }
 113
 114 struct section *find_section_by_name(struct elf *elf, const char *name)
 115 {
 116         struct section *sec;
 117
 118         hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name))
 119                 if (!strcmp(sec->name, name))
 120                         return sec;
 121
 122         return NULL;
 123 }
 124
 125 static struct section *find_section_by_index(struct elf *elf,
 126                                              unsigned int idx)
 127 {
 128         struct section *sec;
 129
 130         hash_for_each_possible(elf->section_hash, sec, hash, idx)
 131                 if (sec->idx == idx)
 132                         return sec;
 133
 134         return NULL;
 135 }
 136
 137 static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
 138 {
 139         struct symbol *sym;
 140
 141         hash_for_each_possible(elf->symbol_hash, sym, hash, idx)
 142                 if (sym->idx == idx)
 143                         return sym;
 144
 145         return NULL;
 146 }
 147
 148 struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
 149 {
 150         struct rb_node *node;
 151
 152         rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
 153                 struct symbol *s = rb_entry(node, struct symbol, node);
 154
 155                 if (s->offset == offset && s->type != STT_SECTION)
 156                         return s;
 157         }
 158
 159         return NULL;
 160 }
 161
 162 struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
 163 {
 164         struct rb_node *node;
 165
 166         rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
 167                 struct symbol *s = rb_entry(node, struct symbol, node);
 168
 169                 if (s->offset == offset && s->type == STT_FUNC)
 170                         return s;
 171         }
 172
 173         return NULL;
 174 }
 175
 176 struct symbol *find_symbol_containing(struct section *sec, unsigned long offset)
 177 {
 178         struct rb_node *node;
 179
 180         rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
 181                 struct symbol *s = rb_entry(node, struct symbol, node);
 182
 183                 if (s->type != STT_SECTION)
 184                         return s;
 185         }
 186
 187         return NULL;
 188 }
 189
 190 struct symbol *find_func_containing(struct section *sec, unsigned long offset)
 191 {
 192         struct rb_node *node;
 193
 194         rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
 195                 struct symbol *s = rb_entry(node, struct symbol, node);
 196
 197                 if (s->type == STT_FUNC)
 198                         return s;
 199         }
 200
 201         return NULL;
 202 }
 203
 204 struct symbol *find_symbol_by_name(struct elf *elf, const char *name)
 205 {
 206         struct symbol *sym;
 207
 208         hash_for_each_possible(elf->symbol_name_hash, sym, name_hash, str_hash(name))
 209                 if (!strcmp(sym->name, name))
 210                         return sym;
 211
 212         return NULL;
 213 }
 214
 215 struct rela *find_rela_by_dest_range(struct elf *elf, struct section *sec,
 216                                      unsigned long offset, unsigned int len)
 217 {
 218         struct rela *rela, *r = NULL;
 219         unsigned long o;
 220
 221         if (!sec->rela)
 222                 return NULL;
 223
 224         sec = sec->rela;
 225
 226         for_offset_range(o, offset, offset + len) {
 227                 hash_for_each_possible(elf->rela_hash, rela, hash,
 228                                        sec_offset_hash(sec, o)) {
 229                         if (rela->sec != sec)
 230                                 continue;
 231
 232                         if (rela->offset >= offset && rela->offset < offset + len) {
 233                                 if (!r || rela->offset < r->offset)
 234                                         r = rela;
 235                         }
 236                 }
 237                 if (r)
 238                         return r;
 239         }
 240
 241         return NULL;
 242 }
 243
 244 struct rela *find_rela_by_dest(struct elf *elf, struct section *sec, unsigned long offset)
 245 {
 246         return find_rela_by_dest_range(elf, sec, offset, 1);
 247 }
 248
 249 static int read_sections(struct elf *elf)
 250 {
 251         Elf_Scn *s = NULL;
 252         struct section *sec;
 253         size_t shstrndx, sections_nr;
 254         int i;
 255
 256         if (elf_getshdrnum(elf->elf, &sections_nr)) {
 257                 WARN_ELF("elf_getshdrnum");
 258                 return -1;
 259         }
 260
 261         if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
 262                 WARN_ELF("elf_getshdrstrndx");
 263                 return -1;
 264         }
 265
 266         for (i = 0; i < sections_nr; i++) {
 267                 sec = malloc(sizeof(*sec));
 268                 if (!sec) {
 269                         perror("malloc");
 270                         return -1;
 271                 }
 272                 memset(sec, 0, sizeof(*sec));
 273
 274                 INIT_LIST_HEAD(&sec->symbol_list);
 275                 INIT_LIST_HEAD(&sec->rela_list);
 276
 277                 s = elf_getscn(elf->elf, i);
 278                 if (!s) {
 279                         WARN_ELF("elf_getscn");
 280                         return -1;
 281                 }
 282
 283                 sec->idx = elf_ndxscn(s);
 284
 285                 if (!gelf_getshdr(s, &sec->sh)) {
 286                         WARN_ELF("gelf_getshdr");
 287                         return -1;
 288                 }
 289
 290                 sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
 291                 if (!sec->name) {
 292                         WARN_ELF("elf_strptr");
 293                         return -1;
 294                 }
 295
 296                 if (sec->sh.sh_size != 0) {
 297                         sec->data = elf_getdata(s, NULL);
 298                         if (!sec->data) {
 299                                 WARN_ELF("elf_getdata");
 300                                 return -1;
 301                         }
 302                         if (sec->data->d_off != 0 ||
 303                             sec->data->d_size != sec->sh.sh_size) {
 304                                 WARN("unexpected data attributes for %s",
 305                                      sec->name);
 306                                 return -1;
 307                         }
 308                 }
 309                 sec->len = sec->sh.sh_size;
 310
 311                 list_add_tail(&sec->list, &elf->sections);
 312                 hash_add(elf->section_hash, &sec->hash, sec->idx);
 313                 hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
 314         }
 315
 316         if (stats)
 317                 printf("nr_sections: %lu\n", (unsigned long)sections_nr);
 318
 319         /* sanity check, one more call to elf_nextscn() should return NULL */
 320         if (elf_nextscn(elf->elf, s)) {
 321                 WARN("section entry mismatch");
 322                 return -1;
 323         }
 324
 325         return 0;
 326 }
 327
 328 static int read_symbols(struct elf *elf)
 329 {
 330         struct section *symtab, *sec;
 331         struct symbol *sym, *pfunc;
 332         struct list_head *entry;
 333         struct rb_node *pnode;
 334         int symbols_nr, i;
 335         char *coldstr;
 336
 337         symtab = find_section_by_name(elf, ".symtab");
 338         if (!symtab) {
 339                 WARN("missing symbol table");
 340                 return -1;
 341         }
 342
 343         symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
 344
 345         for (i = 0; i < symbols_nr; i++) {
 346                 sym = malloc(sizeof(*sym));
 347                 if (!sym) {
 348                         perror("malloc");
 349                         return -1;
 350                 }
 351                 memset(sym, 0, sizeof(*sym));
 352                 sym->alias = sym;
 353
 354                 sym->idx = i;
 355
 356                 if (!gelf_getsym(symtab->data, i, &sym->sym)) {
 357                         WARN_ELF("gelf_getsym");
 358                         goto err;
 359                 }
 360
 361                 sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
 362                                        sym->sym.st_name);
 363                 if (!sym->name) {
 364                         WARN_ELF("elf_strptr");
 365                         goto err;
 366                 }
 367
 368                 sym->type = GELF_ST_TYPE(sym->sym.st_info);
 369                 sym->bind = GELF_ST_BIND(sym->sym.st_info);
 370
 371                 if (sym->sym.st_shndx > SHN_UNDEF &&
 372                     sym->sym.st_shndx < SHN_LORESERVE) {
 373                         sym->sec = find_section_by_index(elf,
 374                                                          sym->sym.st_shndx);
 375                         if (!sym->sec) {
 376                                 WARN("couldn't find section for symbol %s",
 377                                      sym->name);
 378                                 goto err;
 379                         }
 380                         if (sym->type == STT_SECTION) {
 381                                 sym->name = sym->sec->name;
 382                                 sym->sec->sym = sym;
 383                         }
 384                 } else
 385                         sym->sec = find_section_by_index(elf, 0);
 386
 387                 sym->offset = sym->sym.st_value;
 388                 sym->len = sym->sym.st_size;
 389
 390                 rb_add(&sym->sec->symbol_tree, &sym->node, symbol_to_offset);
 391                 pnode = rb_prev(&sym->node);
 392                 if (pnode)
 393                         entry = &rb_entry(pnode, struct symbol, node)->list;
 394                 else
 395                         entry = &sym->sec->symbol_list;
 396                 list_add(&sym->list, entry);
 397                 hash_add(elf->symbol_hash, &sym->hash, sym->idx);
 398                 hash_add(elf->symbol_name_hash, &sym->name_hash, str_hash(sym->name));
 399         }
 400
 401         if (stats)
 402                 printf("nr_symbols: %lu\n", (unsigned long)symbols_nr);
 403
 404         /* Create parent/child links for any cold subfunctions */
 405         list_for_each_entry(sec, &elf->sections, list) {
 406                 list_for_each_entry(sym, &sec->symbol_list, list) {
 407                         char pname[MAX_NAME_LEN + 1];
 408                         size_t pnamelen;
 409                         if (sym->type != STT_FUNC)
 410                                 continue;
 411                         sym->pfunc = sym->cfunc = sym;
 412                         coldstr = strstr(sym->name, ".cold");
 413                         if (!coldstr)
 414                                 continue;
 415
 416                         pnamelen = coldstr - sym->name;
 417                         if (pnamelen > MAX_NAME_LEN) {
 418                                 WARN("%s(): parent function name exceeds maximum length of %d characters",
 419                                      sym->name, MAX_NAME_LEN);
 420                                 return -1;
 421                         }
 422
 423                         strncpy(pname, sym->name, pnamelen);
 424                         pname[pnamelen] = '\0';
 425                         pfunc = find_symbol_by_name(elf, pname);
 426
 427                         if (!pfunc) {
 428                                 WARN("%s(): can't find parent function",
 429                                      sym->name);
 430                                 return -1;
 431                         }
 432
 433                         sym->pfunc = pfunc;
 434                         pfunc->cfunc = sym;
 435
 436                         /*
 437                          * Unfortunately, -fnoreorder-functions puts the child
 438                          * inside the parent.  Remove the overlap so we can
 439                          * have sane assumptions.
 440                          *
 441                          * Note that pfunc->len now no longer matches
 442                          * pfunc->sym.st_size.
 443                          */
 444                         if (sym->sec == pfunc->sec &&
 445                             sym->offset >= pfunc->offset &&
 446                             sym->offset + sym->len == pfunc->offset + pfunc->len) {
 447                                 pfunc->len -= sym->len;
 448                         }
 449                 }
 450         }
 451
 452         return 0;
 453
 454 err:
 455         free(sym);
 456         return -1;
 457 }
 458
 459 static int read_relas(struct elf *elf)
 460 {
 461         struct section *sec;
 462         struct rela *rela;
 463         int i;
 464         unsigned int symndx;
 465         unsigned long nr_rela, max_rela = 0, tot_rela = 0;
 466
 467         list_for_each_entry(sec, &elf->sections, list) {
 468                 if (sec->sh.sh_type != SHT_RELA)
 469                         continue;
 470
 471                 sec->base = find_section_by_name(elf, sec->name + 5);
 472                 if (!sec->base) {
 473                         WARN("can't find base section for rela section %s",
 474                              sec->name);
 475                         return -1;
 476                 }
 477
 478                 sec->base->rela = sec;
 479
 480                 nr_rela = 0;
 481                 for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
 482                         rela = malloc(sizeof(*rela));
 483                         if (!rela) {
 484                                 perror("malloc");
 485                                 return -1;
 486                         }
 487                         memset(rela, 0, sizeof(*rela));
 488
 489                         if (!gelf_getrela(sec->data, i, &rela->rela)) {
 490                                 WARN_ELF("gelf_getrela");
 491                                 return -1;
 492                         }
 493
 494                         rela->type = GELF_R_TYPE(rela->rela.r_info);
 495                         rela->addend = rela->rela.r_addend;
 496                         rela->offset = rela->rela.r_offset;
 497                         symndx = GELF_R_SYM(rela->rela.r_info);
 498                         rela->sym = find_symbol_by_index(elf, symndx);
 499                         rela->sec = sec;
 500                         if (!rela->sym) {
 501                                 WARN("can't find rela entry symbol %d for %s",
 502                                      symndx, sec->name);
 503                                 return -1;
 504                         }
 505
 506                         list_add_tail(&rela->list, &sec->rela_list);
 507                         hash_add(elf->rela_hash, &rela->hash, rela_hash(rela));
 508                         nr_rela++;
 509                 }
 510                 max_rela = max(max_rela, nr_rela);
 511                 tot_rela += nr_rela;
 512         }
 513
 514         if (stats) {
 515                 printf("max_rela: %lu\n", max_rela);
 516                 printf("tot_rela: %lu\n", tot_rela);
 517         }
 518
 519         return 0;
 520 }
 521
 522 struct elf *elf_read(const char *name, int flags)
 523 {
 524         struct elf *elf;
 525         Elf_Cmd cmd;
 526
 527         elf_version(EV_CURRENT);
 528
 529         elf = malloc(sizeof(*elf));
 530         if (!elf) {
 531                 perror("malloc");
 532                 return NULL;
 533         }
 534         memset(elf, 0, sizeof(*elf));
 535
 536         hash_init(elf->symbol_hash);
 537         hash_init(elf->symbol_name_hash);
 538         hash_init(elf->section_hash);
 539         hash_init(elf->section_name_hash);
 540         hash_init(elf->rela_hash);
 541         INIT_LIST_HEAD(&elf->sections);
 542
 543         elf->fd = open(name, flags);
 544         if (elf->fd == -1) {
 545                 fprintf(stderr, "objtool: Can't open '%s': %s\n",
 546                         name, strerror(errno));
 547                 goto err;
 548         }
 549
 550         if ((flags & O_ACCMODE) == O_RDONLY)
 551                 cmd = ELF_C_READ_MMAP;
 552         else if ((flags & O_ACCMODE) == O_RDWR)
 553                 cmd = ELF_C_RDWR;
 554         else /* O_WRONLY */
 555                 cmd = ELF_C_WRITE;
 556
 557         elf->elf = elf_begin(elf->fd, cmd, NULL);
 558         if (!elf->elf) {
 559                 WARN_ELF("elf_begin");
 560                 goto err;
 561         }
 562
 563         if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
 564                 WARN_ELF("gelf_getehdr");
 565                 goto err;
 566         }
 567
 568         if (read_sections(elf))
 569                 goto err;
 570
 571         if (read_symbols(elf))
 572                 goto err;
 573
 574         if (read_relas(elf))
 575                 goto err;
 576
 577         return elf;
 578
 579 err:
 580         elf_close(elf);
 581         return NULL;
 582 }
 583
 584 struct section *elf_create_section(struct elf *elf, const char *name,
 585                                    size_t entsize, int nr)
 586 {
 587         struct section *sec, *shstrtab;
 588         size_t size = entsize * nr;
 589         Elf_Scn *s;
 590         Elf_Data *data;
 591
 592         sec = malloc(sizeof(*sec));
 593         if (!sec) {
 594                 perror("malloc");
 595                 return NULL;
 596         }
 597         memset(sec, 0, sizeof(*sec));
 598
 599         INIT_LIST_HEAD(&sec->symbol_list);
 600         INIT_LIST_HEAD(&sec->rela_list);
 601
 602         s = elf_newscn(elf->elf);
 603         if (!s) {
 604                 WARN_ELF("elf_newscn");
 605                 return NULL;
 606         }
 607
 608         sec->name = strdup(name);
 609         if (!sec->name) {
 610                 perror("strdup");
 611                 return NULL;
 612         }
 613
 614         sec->idx = elf_ndxscn(s);
 615         sec->len = size;
 616         sec->changed = true;
 617
 618         sec->data = elf_newdata(s);
 619         if (!sec->data) {
 620                 WARN_ELF("elf_newdata");
 621                 return NULL;
 622         }
 623
 624         sec->data->d_size = size;
 625         sec->data->d_align = 1;
 626
 627         if (size) {
 628                 sec->data->d_buf = malloc(size);
 629                 if (!sec->data->d_buf) {
 630                         perror("malloc");
 631                         return NULL;
 632                 }
 633                 memset(sec->data->d_buf, 0, size);
 634         }
 635
 636         if (!gelf_getshdr(s, &sec->sh)) {
 637                 WARN_ELF("gelf_getshdr");
 638                 return NULL;
 639         }
 640
 641         sec->sh.sh_size = size;
 642         sec->sh.sh_entsize = entsize;
 643         sec->sh.sh_type = SHT_PROGBITS;
 644         sec->sh.sh_addralign = 1;
 645         sec->sh.sh_flags = SHF_ALLOC;
 646
 647
 648         /* Add section name to .shstrtab (or .strtab for Clang) */
 649         shstrtab = find_section_by_name(elf, ".shstrtab");
 650         if (!shstrtab)
 651                 shstrtab = find_section_by_name(elf, ".strtab");
 652         if (!shstrtab) {
 653                 WARN("can't find .shstrtab or .strtab section");
 654                 return NULL;
 655         }
 656
 657         s = elf_getscn(elf->elf, shstrtab->idx);
 658         if (!s) {
 659                 WARN_ELF("elf_getscn");
 660                 return NULL;
 661         }
 662
 663         data = elf_newdata(s);
 664         if (!data) {
 665                 WARN_ELF("elf_newdata");
 666                 return NULL;
 667         }
 668
 669         data->d_buf = sec->name;
 670         data->d_size = strlen(name) + 1;
 671         data->d_align = 1;
 672
 673         sec->sh.sh_name = shstrtab->len;
 674
 675         shstrtab->len += strlen(name) + 1;
 676         shstrtab->changed = true;
 677
 678         list_add_tail(&sec->list, &elf->sections);
 679         hash_add(elf->section_hash, &sec->hash, sec->idx);
 680         hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
 681
 682         return sec;
 683 }
 684
 685 struct section *elf_create_rela_section(struct elf *elf, struct section *base)
 686 {
 687         char *relaname;
 688         struct section *sec;
 689
 690         relaname = malloc(strlen(base->name) + strlen(".rela") + 1);
 691         if (!relaname) {
 692                 perror("malloc");
 693                 return NULL;
 694         }
 695         strcpy(relaname, ".rela");
 696         strcat(relaname, base->name);
 697
 698         sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0);
 699         free(relaname);
 700         if (!sec)
 701                 return NULL;
 702
 703         base->rela = sec;
 704         sec->base = base;
 705
 706         sec->sh.sh_type = SHT_RELA;
 707         sec->sh.sh_addralign = 8;
 708         sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
 709         sec->sh.sh_info = base->idx;
 710         sec->sh.sh_flags = SHF_INFO_LINK;
 711
 712         return sec;
 713 }
 714
 715 int elf_rebuild_rela_section(struct section *sec)
 716 {
 717         struct rela *rela;
 718         int nr, idx = 0, size;
 719         GElf_Rela *relas;
 720
 721         nr = 0;
 722         list_for_each_entry(rela, &sec->rela_list, list)
 723                 nr++;
 724
 725         size = nr * sizeof(*relas);
 726         relas = malloc(size);
 727         if (!relas) {
 728                 perror("malloc");
 729                 return -1;
 730         }
 731
 732         sec->data->d_buf = relas;
 733         sec->data->d_size = size;
 734
 735         sec->sh.sh_size = size;
 736
 737         idx = 0;
 738         list_for_each_entry(rela, &sec->rela_list, list) {
 739                 relas[idx].r_offset = rela->offset;
 740                 relas[idx].r_addend = rela->addend;
 741                 relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type);
 742                 idx++;
 743         }
 744
 745         return 0;
 746 }
 747
 748 int elf_write(struct elf *elf)
 749 {
 750         struct section *sec;
 751         Elf_Scn *s;
 752
 753         /* Update section headers for changed sections: */
 754         list_for_each_entry(sec, &elf->sections, list) {
 755                 if (sec->changed) {
 756                         s = elf_getscn(elf->elf, sec->idx);
 757                         if (!s) {
 758                                 WARN_ELF("elf_getscn");
 759                                 return -1;
 760                         }
 761                         if (!gelf_update_shdr(s, &sec->sh)) {
 762                                 WARN_ELF("gelf_update_shdr");
 763                                 return -1;
 764                         }
 765                 }
 766         }
 767
 768         /* Make sure the new section header entries get updated properly. */
 769         elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
 770
 771         /* Write all changes to the file. */
 772         if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
 773                 WARN_ELF("elf_update");
 774                 return -1;
 775         }
 776
 777         return 0;
 778 }
 779
 780 void elf_close(struct elf *elf)
 781 {
 782         struct section *sec, *tmpsec;
 783         struct symbol *sym, *tmpsym;
 784         struct rela *rela, *tmprela;
 785
 786         if (elf->elf)
 787                 elf_end(elf->elf);
 788
 789         if (elf->fd > 0)
 790                 close(elf->fd);
 791
 792         list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
 793                 list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
 794                         list_del(&sym->list);
 795                         hash_del(&sym->hash);
 796                         free(sym);
 797                 }
 798                 list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) {
 799                         list_del(&rela->list);
 800                         hash_del(&rela->hash);
 801                         free(rela);
 802                 }
 803                 list_del(&sec->list);
 804                 free(sec);
 805         }
 806
 807         free(elf);
 808 }