| 1 | /* ELF linking support for BFD. |
| 2 | Copyright 1995, 1996, 1997, 1998, 1999, 2000, 2001 |
| 3 | Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of BFD, the Binary File Descriptor library. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 2 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program; if not, write to the Free Software |
| 19 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ |
| 20 | |
| 21 | #include "bfd.h" |
| 22 | #include "sysdep.h" |
| 23 | #include "bfdlink.h" |
| 24 | #include "libbfd.h" |
| 25 | #define ARCH_SIZE 0 |
| 26 | #include "elf-bfd.h" |
| 27 | |
| 28 | boolean |
| 29 | _bfd_elf_create_got_section (abfd, info) |
| 30 | bfd *abfd; |
| 31 | struct bfd_link_info *info; |
| 32 | { |
| 33 | flagword flags; |
| 34 | register asection *s; |
| 35 | struct elf_link_hash_entry *h; |
| 36 | struct elf_backend_data *bed = get_elf_backend_data (abfd); |
| 37 | int ptralign; |
| 38 | |
| 39 | /* This function may be called more than once. */ |
| 40 | if (bfd_get_section_by_name (abfd, ".got") != NULL) |
| 41 | return true; |
| 42 | |
| 43 | switch (bed->s->arch_size) |
| 44 | { |
| 45 | case 32: |
| 46 | ptralign = 2; |
| 47 | break; |
| 48 | |
| 49 | case 64: |
| 50 | ptralign = 3; |
| 51 | break; |
| 52 | |
| 53 | default: |
| 54 | bfd_set_error (bfd_error_bad_value); |
| 55 | return false; |
| 56 | } |
| 57 | |
| 58 | flags = (SEC_ALLOC | SEC_LOAD | SEC_HAS_CONTENTS | SEC_IN_MEMORY |
| 59 | | SEC_LINKER_CREATED); |
| 60 | |
| 61 | s = bfd_make_section (abfd, ".got"); |
| 62 | if (s == NULL |
| 63 | || !bfd_set_section_flags (abfd, s, flags) |
| 64 | || !bfd_set_section_alignment (abfd, s, ptralign)) |
| 65 | return false; |
| 66 | |
| 67 | if (bed->want_got_plt) |
| 68 | { |
| 69 | s = bfd_make_section (abfd, ".got.plt"); |
| 70 | if (s == NULL |
| 71 | || !bfd_set_section_flags (abfd, s, flags) |
| 72 | || !bfd_set_section_alignment (abfd, s, ptralign)) |
| 73 | return false; |
| 74 | } |
| 75 | |
| 76 | if (bed->want_got_sym) |
| 77 | { |
| 78 | /* Define the symbol _GLOBAL_OFFSET_TABLE_ at the start of the .got |
| 79 | (or .got.plt) section. We don't do this in the linker script |
| 80 | because we don't want to define the symbol if we are not creating |
| 81 | a global offset table. */ |
| 82 | h = NULL; |
| 83 | if (!(_bfd_generic_link_add_one_symbol |
| 84 | (info, abfd, "_GLOBAL_OFFSET_TABLE_", BSF_GLOBAL, s, |
| 85 | bed->got_symbol_offset, (const char *) NULL, false, |
| 86 | bed->collect, (struct bfd_link_hash_entry **) &h))) |
| 87 | return false; |
| 88 | h->elf_link_hash_flags |= ELF_LINK_HASH_DEF_REGULAR; |
| 89 | h->type = STT_OBJECT; |
| 90 | |
| 91 | if (info->shared |
| 92 | && ! _bfd_elf_link_record_dynamic_symbol (info, h)) |
| 93 | return false; |
| 94 | |
| 95 | elf_hash_table (info)->hgot = h; |
| 96 | } |
| 97 | |
| 98 | /* The first bit of the global offset table is the header. */ |
| 99 | s->_raw_size += bed->got_header_size + bed->got_symbol_offset; |
| 100 | |
| 101 | return true; |
| 102 | } |
| 103 | \f |
| 104 | /* Create dynamic sections when linking against a dynamic object. */ |
| 105 | |
| 106 | boolean |
| 107 | _bfd_elf_create_dynamic_sections (abfd, info) |
| 108 | bfd *abfd; |
| 109 | struct bfd_link_info *info; |
| 110 | { |
| 111 | flagword flags, pltflags; |
| 112 | register asection *s; |
| 113 | struct elf_backend_data *bed = get_elf_backend_data (abfd); |
| 114 | int ptralign; |
| 115 | |
| 116 | switch (bed->s->arch_size) |
| 117 | { |
| 118 | case 32: |
| 119 | ptralign = 2; |
| 120 | break; |
| 121 | |
| 122 | case 64: |
| 123 | ptralign = 3; |
| 124 | break; |
| 125 | |
| 126 | default: |
| 127 | bfd_set_error (bfd_error_bad_value); |
| 128 | return false; |
| 129 | } |
| 130 | |
| 131 | /* We need to create .plt, .rel[a].plt, .got, .got.plt, .dynbss, and |
| 132 | .rel[a].bss sections. */ |
| 133 | |
| 134 | flags = (SEC_ALLOC | SEC_LOAD | SEC_HAS_CONTENTS | SEC_IN_MEMORY |
| 135 | | SEC_LINKER_CREATED); |
| 136 | |
| 137 | pltflags = flags; |
| 138 | pltflags |= SEC_CODE; |
| 139 | if (bed->plt_not_loaded) |
| 140 | pltflags &= ~ (SEC_LOAD | SEC_HAS_CONTENTS); |
| 141 | if (bed->plt_readonly) |
| 142 | pltflags |= SEC_READONLY; |
| 143 | |
| 144 | s = bfd_make_section (abfd, ".plt"); |
| 145 | if (s == NULL |
| 146 | || ! bfd_set_section_flags (abfd, s, pltflags) |
| 147 | || ! bfd_set_section_alignment (abfd, s, bed->plt_alignment)) |
| 148 | return false; |
| 149 | |
| 150 | if (bed->want_plt_sym) |
| 151 | { |
| 152 | /* Define the symbol _PROCEDURE_LINKAGE_TABLE_ at the start of the |
| 153 | .plt section. */ |
| 154 | struct elf_link_hash_entry *h = NULL; |
| 155 | if (! (_bfd_generic_link_add_one_symbol |
| 156 | (info, abfd, "_PROCEDURE_LINKAGE_TABLE_", BSF_GLOBAL, s, |
| 157 | (bfd_vma) 0, (const char *) NULL, false, |
| 158 | get_elf_backend_data (abfd)->collect, |
| 159 | (struct bfd_link_hash_entry **) &h))) |
| 160 | return false; |
| 161 | h->elf_link_hash_flags |= ELF_LINK_HASH_DEF_REGULAR; |
| 162 | h->type = STT_OBJECT; |
| 163 | |
| 164 | if (info->shared |
| 165 | && ! _bfd_elf_link_record_dynamic_symbol (info, h)) |
| 166 | return false; |
| 167 | } |
| 168 | |
| 169 | s = bfd_make_section (abfd, |
| 170 | bed->default_use_rela_p ? ".rela.plt" : ".rel.plt"); |
| 171 | if (s == NULL |
| 172 | || ! bfd_set_section_flags (abfd, s, flags | SEC_READONLY) |
| 173 | || ! bfd_set_section_alignment (abfd, s, ptralign)) |
| 174 | return false; |
| 175 | |
| 176 | if (! _bfd_elf_create_got_section (abfd, info)) |
| 177 | return false; |
| 178 | |
| 179 | if (bed->want_dynbss) |
| 180 | { |
| 181 | /* The .dynbss section is a place to put symbols which are defined |
| 182 | by dynamic objects, are referenced by regular objects, and are |
| 183 | not functions. We must allocate space for them in the process |
| 184 | image and use a R_*_COPY reloc to tell the dynamic linker to |
| 185 | initialize them at run time. The linker script puts the .dynbss |
| 186 | section into the .bss section of the final image. */ |
| 187 | s = bfd_make_section (abfd, ".dynbss"); |
| 188 | if (s == NULL |
| 189 | || ! bfd_set_section_flags (abfd, s, SEC_ALLOC)) |
| 190 | return false; |
| 191 | |
| 192 | /* The .rel[a].bss section holds copy relocs. This section is not |
| 193 | normally needed. We need to create it here, though, so that the |
| 194 | linker will map it to an output section. We can't just create it |
| 195 | only if we need it, because we will not know whether we need it |
| 196 | until we have seen all the input files, and the first time the |
| 197 | main linker code calls BFD after examining all the input files |
| 198 | (size_dynamic_sections) the input sections have already been |
| 199 | mapped to the output sections. If the section turns out not to |
| 200 | be needed, we can discard it later. We will never need this |
| 201 | section when generating a shared object, since they do not use |
| 202 | copy relocs. */ |
| 203 | if (! info->shared) |
| 204 | { |
| 205 | s = bfd_make_section (abfd, |
| 206 | (bed->default_use_rela_p |
| 207 | ? ".rela.bss" : ".rel.bss")); |
| 208 | if (s == NULL |
| 209 | || ! bfd_set_section_flags (abfd, s, flags | SEC_READONLY) |
| 210 | || ! bfd_set_section_alignment (abfd, s, ptralign)) |
| 211 | return false; |
| 212 | } |
| 213 | } |
| 214 | |
| 215 | return true; |
| 216 | } |
| 217 | \f |
| 218 | /* Record a new dynamic symbol. We record the dynamic symbols as we |
| 219 | read the input files, since we need to have a list of all of them |
| 220 | before we can determine the final sizes of the output sections. |
| 221 | Note that we may actually call this function even though we are not |
| 222 | going to output any dynamic symbols; in some cases we know that a |
| 223 | symbol should be in the dynamic symbol table, but only if there is |
| 224 | one. */ |
| 225 | |
| 226 | boolean |
| 227 | _bfd_elf_link_record_dynamic_symbol (info, h) |
| 228 | struct bfd_link_info *info; |
| 229 | struct elf_link_hash_entry *h; |
| 230 | { |
| 231 | if (h->dynindx == -1) |
| 232 | { |
| 233 | struct elf_strtab_hash *dynstr; |
| 234 | char *p, *alc; |
| 235 | const char *name; |
| 236 | boolean copy; |
| 237 | bfd_size_type indx; |
| 238 | |
| 239 | /* XXX: The ABI draft says the linker must turn hidden and |
| 240 | internal symbols into STB_LOCAL symbols when producing the |
| 241 | DSO. However, if ld.so honors st_other in the dynamic table, |
| 242 | this would not be necessary. */ |
| 243 | switch (ELF_ST_VISIBILITY (h->other)) |
| 244 | { |
| 245 | case STV_INTERNAL: |
| 246 | case STV_HIDDEN: |
| 247 | if (h->root.type != bfd_link_hash_undefined |
| 248 | && h->root.type != bfd_link_hash_undefweak) |
| 249 | { |
| 250 | h->elf_link_hash_flags |= ELF_LINK_FORCED_LOCAL; |
| 251 | return true; |
| 252 | } |
| 253 | |
| 254 | default: |
| 255 | break; |
| 256 | } |
| 257 | |
| 258 | h->dynindx = elf_hash_table (info)->dynsymcount; |
| 259 | ++elf_hash_table (info)->dynsymcount; |
| 260 | |
| 261 | dynstr = elf_hash_table (info)->dynstr; |
| 262 | if (dynstr == NULL) |
| 263 | { |
| 264 | /* Create a strtab to hold the dynamic symbol names. */ |
| 265 | elf_hash_table (info)->dynstr = dynstr = _bfd_elf_strtab_init (); |
| 266 | if (dynstr == NULL) |
| 267 | return false; |
| 268 | } |
| 269 | |
| 270 | /* We don't put any version information in the dynamic string |
| 271 | table. */ |
| 272 | name = h->root.root.string; |
| 273 | p = strchr (name, ELF_VER_CHR); |
| 274 | if (p == NULL) |
| 275 | { |
| 276 | alc = NULL; |
| 277 | copy = false; |
| 278 | } |
| 279 | else |
| 280 | { |
| 281 | alc = bfd_malloc ((bfd_size_type) (p - name + 1)); |
| 282 | if (alc == NULL) |
| 283 | return false; |
| 284 | strncpy (alc, name, (size_t) (p - name)); |
| 285 | alc[p - name] = '\0'; |
| 286 | name = alc; |
| 287 | copy = true; |
| 288 | } |
| 289 | |
| 290 | indx = _bfd_elf_strtab_add (dynstr, name, copy); |
| 291 | |
| 292 | if (alc != NULL) |
| 293 | free (alc); |
| 294 | |
| 295 | if (indx == (bfd_size_type) -1) |
| 296 | return false; |
| 297 | h->dynstr_index = indx; |
| 298 | } |
| 299 | |
| 300 | return true; |
| 301 | } |
| 302 | |
| 303 | /* Return the dynindex of a local dynamic symbol. */ |
| 304 | |
| 305 | long |
| 306 | _bfd_elf_link_lookup_local_dynindx (info, input_bfd, input_indx) |
| 307 | struct bfd_link_info *info; |
| 308 | bfd *input_bfd; |
| 309 | long input_indx; |
| 310 | { |
| 311 | struct elf_link_local_dynamic_entry *e; |
| 312 | |
| 313 | for (e = elf_hash_table (info)->dynlocal; e ; e = e->next) |
| 314 | if (e->input_bfd == input_bfd && e->input_indx == input_indx) |
| 315 | return e->dynindx; |
| 316 | return -1; |
| 317 | } |
| 318 | |
| 319 | /* This function is used to renumber the dynamic symbols, if some of |
| 320 | them are removed because they are marked as local. This is called |
| 321 | via elf_link_hash_traverse. */ |
| 322 | |
| 323 | static boolean elf_link_renumber_hash_table_dynsyms |
| 324 | PARAMS ((struct elf_link_hash_entry *, PTR)); |
| 325 | |
| 326 | static boolean |
| 327 | elf_link_renumber_hash_table_dynsyms (h, data) |
| 328 | struct elf_link_hash_entry *h; |
| 329 | PTR data; |
| 330 | { |
| 331 | size_t *count = (size_t *) data; |
| 332 | |
| 333 | if (h->dynindx != -1) |
| 334 | h->dynindx = ++(*count); |
| 335 | |
| 336 | return true; |
| 337 | } |
| 338 | |
| 339 | /* Assign dynsym indices. In a shared library we generate a section |
| 340 | symbol for each output section, which come first. Next come all of |
| 341 | the back-end allocated local dynamic syms, followed by the rest of |
| 342 | the global symbols. */ |
| 343 | |
| 344 | unsigned long |
| 345 | _bfd_elf_link_renumber_dynsyms (output_bfd, info) |
| 346 | bfd *output_bfd; |
| 347 | struct bfd_link_info *info; |
| 348 | { |
| 349 | unsigned long dynsymcount = 0; |
| 350 | |
| 351 | if (info->shared) |
| 352 | { |
| 353 | asection *p; |
| 354 | for (p = output_bfd->sections; p ; p = p->next) |
| 355 | elf_section_data (p)->dynindx = ++dynsymcount; |
| 356 | } |
| 357 | |
| 358 | if (elf_hash_table (info)->dynlocal) |
| 359 | { |
| 360 | struct elf_link_local_dynamic_entry *p; |
| 361 | for (p = elf_hash_table (info)->dynlocal; p ; p = p->next) |
| 362 | p->dynindx = ++dynsymcount; |
| 363 | } |
| 364 | |
| 365 | elf_link_hash_traverse (elf_hash_table (info), |
| 366 | elf_link_renumber_hash_table_dynsyms, |
| 367 | &dynsymcount); |
| 368 | |
| 369 | /* There is an unused NULL entry at the head of the table which |
| 370 | we must account for in our count. Unless there weren't any |
| 371 | symbols, which means we'll have no table at all. */ |
| 372 | if (dynsymcount != 0) |
| 373 | ++dynsymcount; |
| 374 | |
| 375 | return elf_hash_table (info)->dynsymcount = dynsymcount; |
| 376 | } |
| 377 | \f |
| 378 | /* Create a special linker section, or return a pointer to a linker |
| 379 | section already created */ |
| 380 | |
| 381 | elf_linker_section_t * |
| 382 | _bfd_elf_create_linker_section (abfd, info, which, defaults) |
| 383 | bfd *abfd; |
| 384 | struct bfd_link_info *info; |
| 385 | enum elf_linker_section_enum which; |
| 386 | elf_linker_section_t *defaults; |
| 387 | { |
| 388 | bfd *dynobj = elf_hash_table (info)->dynobj; |
| 389 | elf_linker_section_t *lsect; |
| 390 | |
| 391 | /* Record the first bfd section that needs the special section */ |
| 392 | if (!dynobj) |
| 393 | dynobj = elf_hash_table (info)->dynobj = abfd; |
| 394 | |
| 395 | /* If this is the first time, create the section */ |
| 396 | lsect = elf_linker_section (dynobj, which); |
| 397 | if (!lsect) |
| 398 | { |
| 399 | asection *s; |
| 400 | bfd_size_type amt = sizeof (elf_linker_section_t); |
| 401 | |
| 402 | lsect = (elf_linker_section_t *) bfd_alloc (dynobj, amt); |
| 403 | |
| 404 | *lsect = *defaults; |
| 405 | elf_linker_section (dynobj, which) = lsect; |
| 406 | lsect->which = which; |
| 407 | lsect->hole_written_p = false; |
| 408 | |
| 409 | /* See if the sections already exist */ |
| 410 | lsect->section = s = bfd_get_section_by_name (dynobj, lsect->name); |
| 411 | if (!s || (s->flags & defaults->flags) != defaults->flags) |
| 412 | { |
| 413 | lsect->section = s = bfd_make_section_anyway (dynobj, lsect->name); |
| 414 | |
| 415 | if (s == NULL) |
| 416 | return (elf_linker_section_t *)0; |
| 417 | |
| 418 | bfd_set_section_flags (dynobj, s, defaults->flags); |
| 419 | bfd_set_section_alignment (dynobj, s, lsect->alignment); |
| 420 | } |
| 421 | else if (bfd_get_section_alignment (dynobj, s) < lsect->alignment) |
| 422 | bfd_set_section_alignment (dynobj, s, lsect->alignment); |
| 423 | |
| 424 | s->_raw_size = align_power (s->_raw_size, lsect->alignment); |
| 425 | |
| 426 | /* Is there a hole we have to provide? If so check whether the segment is |
| 427 | too big already */ |
| 428 | if (lsect->hole_size) |
| 429 | { |
| 430 | lsect->hole_offset = s->_raw_size; |
| 431 | s->_raw_size += lsect->hole_size; |
| 432 | if (lsect->hole_offset > lsect->max_hole_offset) |
| 433 | { |
| 434 | (*_bfd_error_handler) (_("%s: Section %s is too large to add hole of %ld bytes"), |
| 435 | bfd_get_filename (abfd), |
| 436 | lsect->name, |
| 437 | (long) lsect->hole_size); |
| 438 | |
| 439 | bfd_set_error (bfd_error_bad_value); |
| 440 | return (elf_linker_section_t *)0; |
| 441 | } |
| 442 | } |
| 443 | |
| 444 | #ifdef DEBUG |
| 445 | fprintf (stderr, "Creating section %s, current size = %ld\n", |
| 446 | lsect->name, (long)s->_raw_size); |
| 447 | #endif |
| 448 | |
| 449 | if (lsect->sym_name) |
| 450 | { |
| 451 | struct elf_link_hash_entry *h = NULL; |
| 452 | #ifdef DEBUG |
| 453 | fprintf (stderr, "Adding %s to section %s\n", |
| 454 | lsect->sym_name, |
| 455 | lsect->name); |
| 456 | #endif |
| 457 | h = (struct elf_link_hash_entry *) |
| 458 | bfd_link_hash_lookup (info->hash, lsect->sym_name, false, false, false); |
| 459 | |
| 460 | if ((h == NULL || h->root.type == bfd_link_hash_undefined) |
| 461 | && !(_bfd_generic_link_add_one_symbol (info, |
| 462 | abfd, |
| 463 | lsect->sym_name, |
| 464 | BSF_GLOBAL, |
| 465 | s, |
| 466 | ((lsect->hole_size) |
| 467 | ? s->_raw_size - lsect->hole_size + lsect->sym_offset |
| 468 | : lsect->sym_offset), |
| 469 | (const char *) NULL, |
| 470 | false, |
| 471 | get_elf_backend_data (abfd)->collect, |
| 472 | (struct bfd_link_hash_entry **) &h))) |
| 473 | return (elf_linker_section_t *)0; |
| 474 | |
| 475 | if ((defaults->which != LINKER_SECTION_SDATA) |
| 476 | && (defaults->which != LINKER_SECTION_SDATA2)) |
| 477 | h->elf_link_hash_flags |= ELF_LINK_HASH_DEF_DYNAMIC; |
| 478 | |
| 479 | h->type = STT_OBJECT; |
| 480 | lsect->sym_hash = h; |
| 481 | |
| 482 | if (info->shared |
| 483 | && ! _bfd_elf_link_record_dynamic_symbol (info, h)) |
| 484 | return (elf_linker_section_t *)0; |
| 485 | } |
| 486 | } |
| 487 | |
| 488 | #if 0 |
| 489 | /* This does not make sense. The sections which may exist in the |
| 490 | object file have nothing to do with the sections we want to |
| 491 | create. */ |
| 492 | |
| 493 | /* Find the related sections if they have been created */ |
| 494 | if (lsect->bss_name && !lsect->bss_section) |
| 495 | lsect->bss_section = bfd_get_section_by_name (dynobj, lsect->bss_name); |
| 496 | |
| 497 | if (lsect->rel_name && !lsect->rel_section) |
| 498 | lsect->rel_section = bfd_get_section_by_name (dynobj, lsect->rel_name); |
| 499 | #endif |
| 500 | |
| 501 | return lsect; |
| 502 | } |
| 503 | \f |
| 504 | /* Find a linker generated pointer with a given addend and type. */ |
| 505 | |
| 506 | elf_linker_section_pointers_t * |
| 507 | _bfd_elf_find_pointer_linker_section (linker_pointers, addend, which) |
| 508 | elf_linker_section_pointers_t *linker_pointers; |
| 509 | bfd_vma addend; |
| 510 | elf_linker_section_enum_t which; |
| 511 | { |
| 512 | for ( ; linker_pointers != NULL; linker_pointers = linker_pointers->next) |
| 513 | { |
| 514 | if (which == linker_pointers->which && addend == linker_pointers->addend) |
| 515 | return linker_pointers; |
| 516 | } |
| 517 | |
| 518 | return (elf_linker_section_pointers_t *)0; |
| 519 | } |
| 520 | \f |
| 521 | /* Make the .rela section corresponding to the generated linker section. */ |
| 522 | |
| 523 | boolean |
| 524 | _bfd_elf_make_linker_section_rela (dynobj, lsect, alignment) |
| 525 | bfd *dynobj; |
| 526 | elf_linker_section_t *lsect; |
| 527 | int alignment; |
| 528 | { |
| 529 | if (lsect->rel_section) |
| 530 | return true; |
| 531 | |
| 532 | lsect->rel_section = bfd_get_section_by_name (dynobj, lsect->rel_name); |
| 533 | if (lsect->rel_section == NULL) |
| 534 | { |
| 535 | lsect->rel_section = bfd_make_section (dynobj, lsect->rel_name); |
| 536 | if (lsect->rel_section == NULL |
| 537 | || ! bfd_set_section_flags (dynobj, |
| 538 | lsect->rel_section, |
| 539 | (SEC_ALLOC |
| 540 | | SEC_LOAD |
| 541 | | SEC_HAS_CONTENTS |
| 542 | | SEC_IN_MEMORY |
| 543 | | SEC_LINKER_CREATED |
| 544 | | SEC_READONLY)) |
| 545 | || ! bfd_set_section_alignment (dynobj, lsect->rel_section, alignment)) |
| 546 | return false; |
| 547 | } |
| 548 | |
| 549 | return true; |
| 550 | } |