Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame^] | 1 | /* Relocate debug information. |
| 2 | Copyright (C) 2005-2010 Red Hat, Inc. |
| 3 | This file is part of Red Hat elfutils. |
| 4 | |
| 5 | Red Hat elfutils is free software; you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by the |
| 7 | Free Software Foundation; version 2 of the License. |
| 8 | |
| 9 | Red Hat elfutils is distributed in the hope that it will be useful, but |
| 10 | WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU General Public License along |
| 15 | with Red Hat elfutils; if not, write to the Free Software Foundation, |
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| 17 | |
| 18 | In addition, as a special exception, Red Hat, Inc. gives You the |
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| 25 | those well defined interfaces identified in the file named EXCEPTION |
| 26 | found in the source code files (the "Approved Interfaces"). The files |
| 27 | of Non-GPL Code may instantiate templates or use macros or inline |
| 28 | functions from the Approved Interfaces without causing the resulting |
| 29 | work to be covered by the GNU General Public License. Only Red Hat, |
| 30 | Inc. may make changes or additions to the list of Approved Interfaces. |
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| 33 | exception, please contact Red Hat. You must obey the GNU General Public |
| 34 | License in all respects for all of the Red Hat elfutils code and other |
| 35 | code used in conjunction with Red Hat elfutils except the Non-GPL Code |
| 36 | covered by this exception. If you modify this file, you may extend this |
| 37 | exception to your version of the file, but you are not obligated to do |
| 38 | so. If you do not wish to provide this exception without modification, |
| 39 | you must delete this exception statement from your version and license |
| 40 | this file solely under the GPL without exception. |
| 41 | |
| 42 | Red Hat elfutils is an included package of the Open Invention Network. |
| 43 | An included package of the Open Invention Network is a package for which |
| 44 | Open Invention Network licensees cross-license their patents. No patent |
| 45 | license is granted, either expressly or impliedly, by designation as an |
| 46 | included package. Should you wish to participate in the Open Invention |
| 47 | Network licensing program, please visit www.openinventionnetwork.com |
| 48 | <http://www.openinventionnetwork.com>. */ |
| 49 | |
| 50 | #include "libdwflP.h" |
| 51 | |
| 52 | typedef uint8_t GElf_Byte; |
| 53 | |
| 54 | /* Adjust *VALUE to add the load address of the SHNDX section. |
| 55 | We update the section header in place to cache the result. */ |
| 56 | |
| 57 | Dwfl_Error |
| 58 | internal_function |
| 59 | __libdwfl_relocate_value (Dwfl_Module *mod, Elf *elf, size_t *shstrndx, |
| 60 | Elf32_Word shndx, GElf_Addr *value) |
| 61 | { |
| 62 | assert (mod->e_type == ET_REL); |
| 63 | |
| 64 | Elf_Scn *refscn = elf_getscn (elf, shndx); |
| 65 | GElf_Shdr refshdr_mem, *refshdr = gelf_getshdr (refscn, &refshdr_mem); |
| 66 | if (refshdr == NULL) |
| 67 | return DWFL_E_LIBELF; |
| 68 | |
| 69 | if (refshdr->sh_addr == 0 && (refshdr->sh_flags & SHF_ALLOC)) |
| 70 | { |
| 71 | /* This is a loaded section. Find its actual |
| 72 | address and update the section header. */ |
| 73 | |
| 74 | if (*shstrndx == SHN_UNDEF |
| 75 | && unlikely (elf_getshdrstrndx (elf, shstrndx) < 0)) |
| 76 | return DWFL_E_LIBELF; |
| 77 | |
| 78 | const char *name = elf_strptr (elf, *shstrndx, refshdr->sh_name); |
| 79 | if (unlikely (name == NULL)) |
| 80 | return DWFL_E_LIBELF; |
| 81 | |
| 82 | if ((*mod->dwfl->callbacks->section_address) (MODCB_ARGS (mod), |
| 83 | name, shndx, refshdr, |
| 84 | &refshdr->sh_addr)) |
| 85 | return CBFAIL; |
| 86 | |
| 87 | if (refshdr->sh_addr == (Dwarf_Addr) -1l) |
| 88 | /* The callback indicated this section wasn't really loaded but we |
| 89 | don't really care. */ |
| 90 | refshdr->sh_addr = 0; /* Make no adjustment below. */ |
| 91 | |
| 92 | /* Update the in-core file's section header to show the final |
| 93 | load address (or unloadedness). This serves as a cache, |
| 94 | so we won't get here again for the same section. */ |
| 95 | if (likely (refshdr->sh_addr != 0) |
| 96 | && unlikely (! gelf_update_shdr (refscn, refshdr))) |
| 97 | return DWFL_E_LIBELF; |
| 98 | } |
| 99 | |
| 100 | if (refshdr->sh_flags & SHF_ALLOC) |
| 101 | /* Apply the adjustment. */ |
| 102 | *value += dwfl_adjusted_address (mod, refshdr->sh_addr); |
| 103 | |
| 104 | return DWFL_E_NOERROR; |
| 105 | } |
| 106 | |
| 107 | |
| 108 | /* Cache used by relocate_getsym. */ |
| 109 | struct reloc_symtab_cache |
| 110 | { |
| 111 | Elf *symelf; |
| 112 | Elf_Data *symdata; |
| 113 | Elf_Data *symxndxdata; |
| 114 | Elf_Data *symstrdata; |
| 115 | size_t symshstrndx; |
| 116 | size_t strtabndx; |
| 117 | }; |
| 118 | #define RELOC_SYMTAB_CACHE(cache) \ |
| 119 | struct reloc_symtab_cache cache = \ |
| 120 | { NULL, NULL, NULL, NULL, SHN_UNDEF, SHN_UNDEF } |
| 121 | |
| 122 | /* This is just doing dwfl_module_getsym, except that we must always use |
| 123 | the symbol table in RELOCATED itself when it has one, not MOD->symfile. */ |
| 124 | static Dwfl_Error |
| 125 | relocate_getsym (Dwfl_Module *mod, |
| 126 | Elf *relocated, struct reloc_symtab_cache *cache, |
| 127 | int symndx, GElf_Sym *sym, GElf_Word *shndx) |
| 128 | { |
| 129 | if (cache->symdata == NULL) |
| 130 | { |
| 131 | if (mod->symfile == NULL || mod->symfile->elf != relocated) |
| 132 | { |
| 133 | /* We have to look up the symbol table in the file we are |
| 134 | relocating, if it has its own. These reloc sections refer to |
| 135 | the symbol table in this file, and a symbol table in the main |
| 136 | file might not match. However, some tools did produce ET_REL |
| 137 | .debug files with relocs but no symtab of their own. */ |
| 138 | Elf_Scn *scn = NULL; |
| 139 | while ((scn = elf_nextscn (relocated, scn)) != NULL) |
| 140 | { |
| 141 | GElf_Shdr shdr_mem, *shdr = gelf_getshdr (scn, &shdr_mem); |
| 142 | if (shdr != NULL) |
| 143 | switch (shdr->sh_type) |
| 144 | { |
| 145 | default: |
| 146 | continue; |
| 147 | case SHT_SYMTAB: |
| 148 | cache->symelf = relocated; |
| 149 | cache->symdata = elf_getdata (scn, NULL); |
| 150 | cache->strtabndx = shdr->sh_link; |
| 151 | if (unlikely (cache->symdata == NULL)) |
| 152 | return DWFL_E_LIBELF; |
| 153 | break; |
| 154 | case SHT_SYMTAB_SHNDX: |
| 155 | cache->symxndxdata = elf_getdata (scn, NULL); |
| 156 | if (unlikely (cache->symxndxdata == NULL)) |
| 157 | return DWFL_E_LIBELF; |
| 158 | break; |
| 159 | } |
| 160 | if (cache->symdata != NULL && cache->symxndxdata != NULL) |
| 161 | break; |
| 162 | } |
| 163 | } |
| 164 | if (cache->symdata == NULL) |
| 165 | { |
| 166 | /* We might not have looked for a symbol table file yet, |
| 167 | when coming from __libdwfl_relocate_section. */ |
| 168 | if (unlikely (mod->symfile == NULL) |
| 169 | && unlikely (INTUSE(dwfl_module_getsymtab) (mod) < 0)) |
| 170 | return dwfl_errno (); |
| 171 | |
| 172 | /* The symbol table we have already cached is the one from |
| 173 | the file being relocated, so it's what we need. Or else |
| 174 | this is an ET_REL .debug file with no .symtab of its own; |
| 175 | the symbols refer to the section indices in the main file. */ |
| 176 | cache->symelf = mod->symfile->elf; |
| 177 | cache->symdata = mod->symdata; |
| 178 | cache->symxndxdata = mod->symxndxdata; |
| 179 | cache->symstrdata = mod->symstrdata; |
| 180 | } |
| 181 | } |
| 182 | |
| 183 | if (unlikely (gelf_getsymshndx (cache->symdata, cache->symxndxdata, |
| 184 | symndx, sym, shndx) == NULL)) |
| 185 | return DWFL_E_LIBELF; |
| 186 | |
| 187 | if (sym->st_shndx != SHN_XINDEX) |
| 188 | *shndx = sym->st_shndx; |
| 189 | |
| 190 | switch (sym->st_shndx) |
| 191 | { |
| 192 | case SHN_ABS: |
| 193 | case SHN_UNDEF: |
| 194 | return DWFL_E_NOERROR; |
| 195 | |
| 196 | case SHN_COMMON: |
| 197 | sym->st_value = 0; /* Value is size, not helpful. */ |
| 198 | return DWFL_E_NOERROR; |
| 199 | } |
| 200 | |
| 201 | return __libdwfl_relocate_value (mod, cache->symelf, &cache->symshstrndx, |
| 202 | *shndx, &sym->st_value); |
| 203 | } |
| 204 | |
| 205 | /* Handle an undefined symbol. We really only support ET_REL for Linux |
| 206 | kernel modules, and offline archives. The behavior of the Linux module |
| 207 | loader is very simple and easy to mimic. It only matches magically |
| 208 | exported symbols, and we match any defined symbols. But we get the same |
| 209 | answer except when the module's symbols are undefined and would prevent |
| 210 | it from being loaded. */ |
| 211 | static Dwfl_Error |
| 212 | resolve_symbol (Dwfl_Module *referer, struct reloc_symtab_cache *symtab, |
| 213 | GElf_Sym *sym, GElf_Word shndx) |
| 214 | { |
| 215 | /* First we need its name. */ |
| 216 | if (sym->st_name != 0) |
| 217 | { |
| 218 | if (symtab->symstrdata == NULL) |
| 219 | { |
| 220 | /* Cache the strtab for this symtab. */ |
| 221 | assert (referer->symfile == NULL |
| 222 | || referer->symfile->elf != symtab->symelf); |
| 223 | symtab->symstrdata = elf_getdata (elf_getscn (symtab->symelf, |
| 224 | symtab->strtabndx), |
| 225 | NULL); |
| 226 | if (unlikely (symtab->symstrdata == NULL)) |
| 227 | return DWFL_E_LIBELF; |
| 228 | } |
| 229 | if (unlikely (sym->st_name >= symtab->symstrdata->d_size)) |
| 230 | return DWFL_E_BADSTROFF; |
| 231 | |
| 232 | const char *name = symtab->symstrdata->d_buf; |
| 233 | name += sym->st_name; |
| 234 | |
| 235 | for (Dwfl_Module *m = referer->dwfl->modulelist; m != NULL; m = m->next) |
| 236 | if (m != referer) |
| 237 | { |
| 238 | /* Get this module's symtab. |
| 239 | If we got a fresh error reading the table, report it. |
| 240 | If we just have no symbols in this module, no harm done. */ |
| 241 | if (m->symdata == NULL |
| 242 | && m->symerr == DWFL_E_NOERROR |
| 243 | && INTUSE(dwfl_module_getsymtab) (m) < 0 |
| 244 | && m->symerr != DWFL_E_NO_SYMTAB) |
| 245 | return m->symerr; |
| 246 | |
| 247 | for (size_t ndx = 1; ndx < m->syments; ++ndx) |
| 248 | { |
| 249 | sym = gelf_getsymshndx (m->symdata, m->symxndxdata, |
| 250 | ndx, sym, &shndx); |
| 251 | if (unlikely (sym == NULL)) |
| 252 | return DWFL_E_LIBELF; |
| 253 | if (sym->st_shndx != SHN_XINDEX) |
| 254 | shndx = sym->st_shndx; |
| 255 | |
| 256 | /* We are looking for a defined global symbol with a name. */ |
| 257 | if (shndx == SHN_UNDEF || shndx == SHN_COMMON |
| 258 | || GELF_ST_BIND (sym->st_info) == STB_LOCAL |
| 259 | || sym->st_name == 0) |
| 260 | continue; |
| 261 | |
| 262 | /* Get this candidate symbol's name. */ |
| 263 | if (unlikely (sym->st_name >= m->symstrdata->d_size)) |
| 264 | return DWFL_E_BADSTROFF; |
| 265 | const char *n = m->symstrdata->d_buf; |
| 266 | n += sym->st_name; |
| 267 | |
| 268 | /* Does the name match? */ |
| 269 | if (strcmp (name, n)) |
| 270 | continue; |
| 271 | |
| 272 | /* We found it! */ |
| 273 | if (shndx == SHN_ABS) /* XXX maybe should apply bias? */ |
| 274 | return DWFL_E_NOERROR; |
| 275 | |
| 276 | if (m->e_type != ET_REL) |
| 277 | { |
| 278 | sym->st_value = dwfl_adjusted_st_value (m, sym->st_value); |
| 279 | return DWFL_E_NOERROR; |
| 280 | } |
| 281 | |
| 282 | /* In an ET_REL file, the symbol table values are relative |
| 283 | to the section, not to the module's load base. */ |
| 284 | size_t symshstrndx = SHN_UNDEF; |
| 285 | return __libdwfl_relocate_value (m, m->symfile->elf, |
| 286 | &symshstrndx, |
| 287 | shndx, &sym->st_value); |
| 288 | } |
| 289 | } |
| 290 | } |
| 291 | |
| 292 | return DWFL_E_RELUNDEF; |
| 293 | } |
| 294 | |
| 295 | static Dwfl_Error |
| 296 | relocate_section (Dwfl_Module *mod, Elf *relocated, const GElf_Ehdr *ehdr, |
| 297 | size_t shstrndx, struct reloc_symtab_cache *reloc_symtab, |
| 298 | Elf_Scn *scn, GElf_Shdr *shdr, |
| 299 | Elf_Scn *tscn, bool debugscn, bool partial) |
| 300 | { |
| 301 | /* First, fetch the name of the section these relocations apply to. */ |
| 302 | GElf_Shdr tshdr_mem; |
| 303 | GElf_Shdr *tshdr = gelf_getshdr (tscn, &tshdr_mem); |
| 304 | const char *tname = elf_strptr (relocated, shstrndx, tshdr->sh_name); |
| 305 | if (tname == NULL) |
| 306 | return DWFL_E_LIBELF; |
| 307 | |
| 308 | if (unlikely (tshdr->sh_type == SHT_NOBITS) || unlikely (tshdr->sh_size == 0)) |
| 309 | /* No contents to relocate. */ |
| 310 | return DWFL_E_NOERROR; |
| 311 | |
| 312 | if (debugscn && ! ebl_debugscn_p (mod->ebl, tname)) |
| 313 | /* This relocation section is not for a debugging section. |
| 314 | Nothing to do here. */ |
| 315 | return DWFL_E_NOERROR; |
| 316 | |
| 317 | /* Fetch the section data that needs the relocations applied. */ |
| 318 | Elf_Data *tdata = elf_rawdata (tscn, NULL); |
| 319 | if (tdata == NULL) |
| 320 | return DWFL_E_LIBELF; |
| 321 | |
| 322 | /* Apply one relocation. Returns true for any invalid data. */ |
| 323 | Dwfl_Error relocate (GElf_Addr offset, const GElf_Sxword *addend, |
| 324 | int rtype, int symndx) |
| 325 | { |
| 326 | /* First see if this is a reloc we can handle. |
| 327 | If we are skipping it, don't bother resolving the symbol. */ |
| 328 | |
| 329 | if (unlikely (rtype == 0)) |
| 330 | /* In some odd situations, the linker can leave R_*_NONE relocs |
| 331 | behind. This is probably bogus ld -r behavior, but the only |
| 332 | cases it's known to appear in are harmless: DWARF data |
| 333 | referring to addresses in a section that has been discarded. |
| 334 | So we just pretend it's OK without further relocation. */ |
| 335 | return DWFL_E_NOERROR; |
| 336 | |
| 337 | Elf_Type type = ebl_reloc_simple_type (mod->ebl, rtype); |
| 338 | if (unlikely (type == ELF_T_NUM)) |
| 339 | return DWFL_E_BADRELTYPE; |
| 340 | |
| 341 | /* First, resolve the symbol to an absolute value. */ |
| 342 | GElf_Addr value; |
| 343 | |
| 344 | if (symndx == STN_UNDEF) |
| 345 | /* When strip removes a section symbol referring to a |
| 346 | section moved into the debuginfo file, it replaces |
| 347 | that symbol index in relocs with STN_UNDEF. We |
| 348 | don't actually need the symbol, because those relocs |
| 349 | are always references relative to the nonallocated |
| 350 | debugging sections, which start at zero. */ |
| 351 | value = 0; |
| 352 | else |
| 353 | { |
| 354 | GElf_Sym sym; |
| 355 | GElf_Word shndx; |
| 356 | Dwfl_Error error = relocate_getsym (mod, relocated, reloc_symtab, |
| 357 | symndx, &sym, &shndx); |
| 358 | if (unlikely (error != DWFL_E_NOERROR)) |
| 359 | return error; |
| 360 | |
| 361 | if (shndx == SHN_UNDEF || shndx == SHN_COMMON) |
| 362 | { |
| 363 | /* Maybe we can figure it out anyway. */ |
| 364 | error = resolve_symbol (mod, reloc_symtab, &sym, shndx); |
| 365 | if (error != DWFL_E_NOERROR |
| 366 | && !(error == DWFL_E_RELUNDEF && shndx == SHN_COMMON)) |
| 367 | return error; |
| 368 | } |
| 369 | |
| 370 | value = sym.st_value; |
| 371 | } |
| 372 | |
| 373 | /* These are the types we can relocate. */ |
| 374 | #define TYPES DO_TYPE (BYTE, Byte); DO_TYPE (HALF, Half); \ |
| 375 | DO_TYPE (WORD, Word); DO_TYPE (SWORD, Sword); \ |
| 376 | DO_TYPE (XWORD, Xword); DO_TYPE (SXWORD, Sxword) |
| 377 | size_t size; |
| 378 | switch (type) |
| 379 | { |
| 380 | #define DO_TYPE(NAME, Name) \ |
| 381 | case ELF_T_##NAME: \ |
| 382 | size = sizeof (GElf_##Name); \ |
| 383 | break |
| 384 | TYPES; |
| 385 | #undef DO_TYPE |
| 386 | default: |
| 387 | return DWFL_E_BADRELTYPE; |
| 388 | } |
| 389 | |
| 390 | if (offset + size > tdata->d_size) |
| 391 | return DWFL_E_BADRELOFF; |
| 392 | |
| 393 | #define DO_TYPE(NAME, Name) GElf_##Name Name; |
| 394 | union { TYPES; } tmpbuf; |
| 395 | #undef DO_TYPE |
| 396 | Elf_Data tmpdata = |
| 397 | { |
| 398 | .d_type = type, |
| 399 | .d_buf = &tmpbuf, |
| 400 | .d_size = size, |
| 401 | .d_version = EV_CURRENT, |
| 402 | }; |
| 403 | Elf_Data rdata = |
| 404 | { |
| 405 | .d_type = type, |
| 406 | .d_buf = tdata->d_buf + offset, |
| 407 | .d_size = size, |
| 408 | .d_version = EV_CURRENT, |
| 409 | }; |
| 410 | |
| 411 | /* XXX check for overflow? */ |
| 412 | if (addend) |
| 413 | { |
| 414 | /* For the addend form, we have the value already. */ |
| 415 | value += *addend; |
| 416 | switch (type) |
| 417 | { |
| 418 | #define DO_TYPE(NAME, Name) \ |
| 419 | case ELF_T_##NAME: \ |
| 420 | tmpbuf.Name = value; \ |
| 421 | break |
| 422 | TYPES; |
| 423 | #undef DO_TYPE |
| 424 | default: |
| 425 | abort (); |
| 426 | } |
| 427 | } |
| 428 | else |
| 429 | { |
| 430 | /* Extract the original value and apply the reloc. */ |
| 431 | Elf_Data *d = gelf_xlatetom (relocated, &tmpdata, &rdata, |
| 432 | ehdr->e_ident[EI_DATA]); |
| 433 | if (d == NULL) |
| 434 | return DWFL_E_LIBELF; |
| 435 | assert (d == &tmpdata); |
| 436 | switch (type) |
| 437 | { |
| 438 | #define DO_TYPE(NAME, Name) \ |
| 439 | case ELF_T_##NAME: \ |
| 440 | tmpbuf.Name += (GElf_##Name) value; \ |
| 441 | break |
| 442 | TYPES; |
| 443 | #undef DO_TYPE |
| 444 | default: |
| 445 | abort (); |
| 446 | } |
| 447 | } |
| 448 | |
| 449 | /* Now convert the relocated datum back to the target |
| 450 | format. This will write into rdata.d_buf, which |
| 451 | points into the raw section data being relocated. */ |
| 452 | Elf_Data *s = gelf_xlatetof (relocated, &rdata, &tmpdata, |
| 453 | ehdr->e_ident[EI_DATA]); |
| 454 | if (s == NULL) |
| 455 | return DWFL_E_LIBELF; |
| 456 | assert (s == &rdata); |
| 457 | |
| 458 | /* We have applied this relocation! */ |
| 459 | return DWFL_E_NOERROR; |
| 460 | } |
| 461 | |
| 462 | /* Fetch the relocation section and apply each reloc in it. */ |
| 463 | Elf_Data *reldata = elf_getdata (scn, NULL); |
| 464 | if (reldata == NULL) |
| 465 | return DWFL_E_LIBELF; |
| 466 | |
| 467 | Dwfl_Error result = DWFL_E_NOERROR; |
| 468 | bool first_badreltype = true; |
| 469 | inline void check_badreltype (void) |
| 470 | { |
| 471 | if (first_badreltype) |
| 472 | { |
| 473 | first_badreltype = false; |
| 474 | if (ebl_get_elfmachine (mod->ebl) == EM_NONE) |
| 475 | /* This might be because ebl_openbackend failed to find |
| 476 | any libebl_CPU.so library. Diagnose that clearly. */ |
| 477 | result = DWFL_E_UNKNOWN_MACHINE; |
| 478 | } |
| 479 | } |
| 480 | |
| 481 | size_t nrels = shdr->sh_size / shdr->sh_entsize; |
| 482 | size_t complete = 0; |
| 483 | if (shdr->sh_type == SHT_REL) |
| 484 | for (size_t relidx = 0; !result && relidx < nrels; ++relidx) |
| 485 | { |
| 486 | GElf_Rel rel_mem, *r = gelf_getrel (reldata, relidx, &rel_mem); |
| 487 | if (r == NULL) |
| 488 | return DWFL_E_LIBELF; |
| 489 | result = relocate (r->r_offset, NULL, |
| 490 | GELF_R_TYPE (r->r_info), |
| 491 | GELF_R_SYM (r->r_info)); |
| 492 | check_badreltype (); |
| 493 | if (partial) |
| 494 | switch (result) |
| 495 | { |
| 496 | case DWFL_E_NOERROR: |
| 497 | /* We applied the relocation. Elide it. */ |
| 498 | memset (&rel_mem, 0, sizeof rel_mem); |
| 499 | gelf_update_rel (reldata, relidx, &rel_mem); |
| 500 | ++complete; |
| 501 | break; |
| 502 | case DWFL_E_BADRELTYPE: |
| 503 | case DWFL_E_RELUNDEF: |
| 504 | /* We couldn't handle this relocation. Skip it. */ |
| 505 | result = DWFL_E_NOERROR; |
| 506 | break; |
| 507 | default: |
| 508 | break; |
| 509 | } |
| 510 | } |
| 511 | else |
| 512 | for (size_t relidx = 0; !result && relidx < nrels; ++relidx) |
| 513 | { |
| 514 | GElf_Rela rela_mem, *r = gelf_getrela (reldata, relidx, |
| 515 | &rela_mem); |
| 516 | if (r == NULL) |
| 517 | return DWFL_E_LIBELF; |
| 518 | result = relocate (r->r_offset, &r->r_addend, |
| 519 | GELF_R_TYPE (r->r_info), |
| 520 | GELF_R_SYM (r->r_info)); |
| 521 | check_badreltype (); |
| 522 | if (partial) |
| 523 | switch (result) |
| 524 | { |
| 525 | case DWFL_E_NOERROR: |
| 526 | /* We applied the relocation. Elide it. */ |
| 527 | memset (&rela_mem, 0, sizeof rela_mem); |
| 528 | gelf_update_rela (reldata, relidx, &rela_mem); |
| 529 | ++complete; |
| 530 | break; |
| 531 | case DWFL_E_BADRELTYPE: |
| 532 | case DWFL_E_RELUNDEF: |
| 533 | /* We couldn't handle this relocation. Skip it. */ |
| 534 | result = DWFL_E_NOERROR; |
| 535 | break; |
| 536 | default: |
| 537 | break; |
| 538 | } |
| 539 | } |
| 540 | |
| 541 | if (likely (result == DWFL_E_NOERROR)) |
| 542 | { |
| 543 | if (!partial || complete == nrels) |
| 544 | /* Mark this relocation section as being empty now that we have |
| 545 | done its work. This affects unstrip -R, so e.g. it emits an |
| 546 | empty .rela.debug_info along with a .debug_info that has |
| 547 | already been fully relocated. */ |
| 548 | nrels = 0; |
| 549 | else if (complete != 0) |
| 550 | { |
| 551 | /* We handled some of the relocations but not all. |
| 552 | We've zeroed out the ones we processed. |
| 553 | Now remove them from the section. */ |
| 554 | |
| 555 | size_t next = 0; |
| 556 | if (shdr->sh_type == SHT_REL) |
| 557 | for (size_t relidx = 0; relidx < nrels; ++relidx) |
| 558 | { |
| 559 | GElf_Rel rel_mem; |
| 560 | GElf_Rel *r = gelf_getrel (reldata, relidx, &rel_mem); |
| 561 | if (r->r_info != 0 || r->r_offset != 0) |
| 562 | { |
| 563 | if (next != relidx) |
| 564 | gelf_update_rel (reldata, next, r); |
| 565 | ++next; |
| 566 | } |
| 567 | } |
| 568 | else |
| 569 | for (size_t relidx = 0; relidx < nrels; ++relidx) |
| 570 | { |
| 571 | GElf_Rela rela_mem; |
| 572 | GElf_Rela *r = gelf_getrela (reldata, relidx, &rela_mem); |
| 573 | if (r->r_info != 0 || r->r_offset != 0 || r->r_addend != 0) |
| 574 | { |
| 575 | if (next != relidx) |
| 576 | gelf_update_rela (reldata, next, r); |
| 577 | ++next; |
| 578 | } |
| 579 | } |
| 580 | nrels = next; |
| 581 | } |
| 582 | |
| 583 | shdr->sh_size = reldata->d_size = nrels * shdr->sh_entsize; |
| 584 | gelf_update_shdr (scn, shdr); |
| 585 | } |
| 586 | |
| 587 | return result; |
| 588 | } |
| 589 | |
| 590 | Dwfl_Error |
| 591 | internal_function |
| 592 | __libdwfl_relocate (Dwfl_Module *mod, Elf *debugfile, bool debug) |
| 593 | { |
| 594 | assert (mod->e_type == ET_REL); |
| 595 | |
| 596 | GElf_Ehdr ehdr_mem; |
| 597 | const GElf_Ehdr *ehdr = gelf_getehdr (debugfile, &ehdr_mem); |
| 598 | if (ehdr == NULL) |
| 599 | return DWFL_E_LIBELF; |
| 600 | |
| 601 | size_t d_shstrndx; |
| 602 | if (elf_getshdrstrndx (debugfile, &d_shstrndx) < 0) |
| 603 | return DWFL_E_LIBELF; |
| 604 | |
| 605 | RELOC_SYMTAB_CACHE (reloc_symtab); |
| 606 | |
| 607 | /* Look at each section in the debuginfo file, and process the |
| 608 | relocation sections for debugging sections. */ |
| 609 | Dwfl_Error result = DWFL_E_NOERROR; |
| 610 | Elf_Scn *scn = NULL; |
| 611 | while (result == DWFL_E_NOERROR |
| 612 | && (scn = elf_nextscn (debugfile, scn)) != NULL) |
| 613 | { |
| 614 | GElf_Shdr shdr_mem; |
| 615 | GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); |
| 616 | |
| 617 | if ((shdr->sh_type == SHT_REL || shdr->sh_type == SHT_RELA) |
| 618 | && shdr->sh_size != 0) |
| 619 | { |
| 620 | /* It's a relocation section. */ |
| 621 | |
| 622 | Elf_Scn *tscn = elf_getscn (debugfile, shdr->sh_info); |
| 623 | if (unlikely (tscn == NULL)) |
| 624 | result = DWFL_E_LIBELF; |
| 625 | else |
| 626 | result = relocate_section (mod, debugfile, ehdr, d_shstrndx, |
| 627 | &reloc_symtab, scn, shdr, tscn, |
| 628 | debug, !debug); |
| 629 | } |
| 630 | } |
| 631 | |
| 632 | return result; |
| 633 | } |
| 634 | |
| 635 | Dwfl_Error |
| 636 | internal_function |
| 637 | __libdwfl_relocate_section (Dwfl_Module *mod, Elf *relocated, |
| 638 | Elf_Scn *relocscn, Elf_Scn *tscn, bool partial) |
| 639 | { |
| 640 | GElf_Ehdr ehdr_mem; |
| 641 | GElf_Shdr shdr_mem; |
| 642 | |
| 643 | RELOC_SYMTAB_CACHE (reloc_symtab); |
| 644 | |
| 645 | size_t shstrndx; |
| 646 | if (elf_getshdrstrndx (relocated, &shstrndx) < 0) |
| 647 | return DWFL_E_LIBELF; |
| 648 | |
| 649 | return (__libdwfl_module_getebl (mod) |
| 650 | ?: relocate_section (mod, relocated, |
| 651 | gelf_getehdr (relocated, &ehdr_mem), shstrndx, |
| 652 | &reloc_symtab, |
| 653 | relocscn, gelf_getshdr (relocscn, &shdr_mem), |
| 654 | tscn, false, partial)); |
| 655 | } |