1 // target-reloc.h -- target specific relocation support -*- C++ -*- 2 3 // Copyright (C) 2006-2016 Free Software Foundation, Inc. 4 // Written by Ian Lance Taylor <iant (at) google.com>. 5 6 // This file is part of gold. 7 8 // This program is free software; you can redistribute it and/or modify 9 // it under the terms of the GNU General Public License as published by 10 // the Free Software Foundation; either version 3 of the License, or 11 // (at your option) any later version. 12 13 // This program is distributed in the hope that it will be useful, 14 // but WITHOUT ANY WARRANTY; without even the implied warranty of 15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 // GNU General Public License for more details. 17 18 // You should have received a copy of the GNU General Public License 19 // along with this program; if not, write to the Free Software 20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, 21 // MA 02110-1301, USA. 22 23 #ifndef GOLD_TARGET_RELOC_H 24 #define GOLD_TARGET_RELOC_H 25 26 #include "elfcpp.h" 27 #include "symtab.h" 28 #include "object.h" 29 #include "reloc.h" 30 #include "reloc-types.h" 31 32 namespace gold 33 { 34 35 // This function implements the generic part of reloc scanning. The 36 // template parameter Scan must be a class type which provides two 37 // functions: local() and global(). Those functions implement the 38 // machine specific part of scanning. We do it this way to 39 // avoid making a function call for each relocation, and to avoid 40 // repeating the generic code for each target. 41 42 template<int size, bool big_endian, typename Target_type, 43 typename Scan, typename Classify_reloc> 44 inline void 45 scan_relocs( 46 Symbol_table* symtab, 47 Layout* layout, 48 Target_type* target, 49 Sized_relobj_file<size, big_endian>* object, 50 unsigned int data_shndx, 51 const unsigned char* prelocs, 52 size_t reloc_count, 53 Output_section* output_section, 54 bool needs_special_offset_handling, 55 size_t local_count, 56 const unsigned char* plocal_syms) 57 { 58 typedef typename Classify_reloc::Reltype Reltype; 59 const int reloc_size = Classify_reloc::reloc_size; 60 const int sym_size = elfcpp::Elf_sizes<size>::sym_size; 61 Scan scan; 62 63 for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size) 64 { 65 Reltype reloc(prelocs); 66 67 if (needs_special_offset_handling 68 && !output_section->is_input_address_mapped(object, data_shndx, 69 reloc.get_r_offset())) 70 continue; 71 72 unsigned int r_sym = Classify_reloc::get_r_sym(&reloc); 73 unsigned int r_type = Classify_reloc::get_r_type(&reloc); 74 75 if (r_sym < local_count) 76 { 77 gold_assert(plocal_syms != NULL); 78 typename elfcpp::Sym<size, big_endian> lsym(plocal_syms 79 + r_sym * sym_size); 80 unsigned int shndx = lsym.get_st_shndx(); 81 bool is_ordinary; 82 shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary); 83 // If RELOC is a relocation against a local symbol in a 84 // section we are discarding then we can ignore it. It will 85 // eventually become a reloc against the value zero. 86 // 87 // FIXME: We should issue a warning if this is an 88 // allocated section; is this the best place to do it? 89 // 90 // FIXME: The old GNU linker would in some cases look 91 // for the linkonce section which caused this section to 92 // be discarded, and, if the other section was the same 93 // size, change the reloc to refer to the other section. 94 // That seems risky and weird to me, and I don't know of 95 // any case where it is actually required. 96 bool is_discarded = (is_ordinary 97 && shndx != elfcpp::SHN_UNDEF 98 && !object->is_section_included(shndx) 99 && !symtab->is_section_folded(object, shndx)); 100 scan.local(symtab, layout, target, object, data_shndx, 101 output_section, reloc, r_type, lsym, is_discarded); 102 } 103 else 104 { 105 Symbol* gsym = object->global_symbol(r_sym); 106 gold_assert(gsym != NULL); 107 if (gsym->is_forwarder()) 108 gsym = symtab->resolve_forwards(gsym); 109 110 scan.global(symtab, layout, target, object, data_shndx, 111 output_section, reloc, r_type, gsym); 112 } 113 } 114 } 115 116 // Behavior for relocations to discarded comdat sections. 117 118 enum Comdat_behavior 119 { 120 CB_UNDETERMINED, // Not yet determined -- need to look at section name. 121 CB_PRETEND, // Attempt to map to the corresponding kept section. 122 CB_IGNORE, // Ignore the relocation. 123 CB_WARNING // Print a warning. 124 }; 125 126 class Default_comdat_behavior 127 { 128 public: 129 // Decide what the linker should do for relocations that refer to 130 // discarded comdat sections. This decision is based on the name of 131 // the section being relocated. 132 133 inline Comdat_behavior 134 get(const char* name) 135 { 136 if (Layout::is_debug_info_section(name)) 137 return CB_PRETEND; 138 if (strcmp(name, ".eh_frame") == 0 139 || strcmp(name, ".gcc_except_table") == 0) 140 return CB_IGNORE; 141 return CB_WARNING; 142 } 143 }; 144 145 // Give an error for a symbol with non-default visibility which is not 146 // defined locally. 147 148 inline void 149 visibility_error(const Symbol* sym) 150 { 151 const char* v; 152 switch (sym->visibility()) 153 { 154 case elfcpp::STV_INTERNAL: 155 v = _("internal"); 156 break; 157 case elfcpp::STV_HIDDEN: 158 v = _("hidden"); 159 break; 160 case elfcpp::STV_PROTECTED: 161 v = _("protected"); 162 break; 163 default: 164 gold_unreachable(); 165 } 166 gold_error(_("%s symbol '%s' is not defined locally"), 167 v, sym->name()); 168 } 169 170 // Return true if we are should issue an error saying that SYM is an 171 // undefined symbol. This is called if there is a relocation against 172 // SYM. 173 174 inline bool 175 issue_undefined_symbol_error(const Symbol* sym) 176 { 177 // We only report global symbols. 178 if (sym == NULL) 179 return false; 180 181 // We only report undefined symbols. 182 if (!sym->is_undefined() && !sym->is_placeholder()) 183 return false; 184 185 // We don't report weak symbols. 186 if (sym->is_weak_undefined()) 187 return false; 188 189 // We don't report symbols defined in discarded sections, 190 // unless they're placeholder symbols that should have been 191 // provided by a plugin. 192 if (sym->is_defined_in_discarded_section() && !sym->is_placeholder()) 193 return false; 194 195 // If the target defines this symbol, don't report it here. 196 if (parameters->target().is_defined_by_abi(sym)) 197 return false; 198 199 // See if we've been told to ignore whether this symbol is 200 // undefined. 201 const char* const u = parameters->options().unresolved_symbols(); 202 if (u != NULL) 203 { 204 if (strcmp(u, "ignore-all") == 0) 205 return false; 206 if (strcmp(u, "report-all") == 0) 207 return true; 208 if (strcmp(u, "ignore-in-object-files") == 0 && !sym->in_dyn()) 209 return false; 210 if (strcmp(u, "ignore-in-shared-libs") == 0 && !sym->in_reg()) 211 return false; 212 } 213 214 // If the symbol is hidden, report it. 215 if (sym->visibility() == elfcpp::STV_HIDDEN) 216 return true; 217 218 // When creating a shared library, only report unresolved symbols if 219 // -z defs was used. 220 if (parameters->options().shared() && !parameters->options().defs()) 221 return false; 222 223 // Otherwise issue a warning. 224 return true; 225 } 226 227 // This function implements the generic part of relocation processing. 228 // The template parameter Relocate must be a class type which provides 229 // a single function, relocate(), which implements the machine 230 // specific part of a relocation. 231 232 // The template parameter Relocate_comdat_behavior is a class type 233 // which provides a single function, get(), which determines what the 234 // linker should do for relocations that refer to discarded comdat 235 // sections. 236 237 // SIZE is the ELF size: 32 or 64. BIG_ENDIAN is the endianness of 238 // the data. SH_TYPE is the section type: SHT_REL or SHT_RELA. 239 // RELOCATE implements operator() to do a relocation. 240 241 // PRELOCS points to the relocation data. RELOC_COUNT is the number 242 // of relocs. OUTPUT_SECTION is the output section. 243 // NEEDS_SPECIAL_OFFSET_HANDLING is true if input offsets need to be 244 // mapped to output offsets. 245 246 // VIEW is the section data, VIEW_ADDRESS is its memory address, and 247 // VIEW_SIZE is the size. These refer to the input section, unless 248 // NEEDS_SPECIAL_OFFSET_HANDLING is true, in which case they refer to 249 // the output section. 250 251 // RELOC_SYMBOL_CHANGES is used for -fsplit-stack support. If it is 252 // not NULL, it is a vector indexed by relocation index. If that 253 // entry is not NULL, it points to a global symbol which used as the 254 // symbol for the relocation, ignoring the symbol index in the 255 // relocation. 256 257 template<int size, bool big_endian, typename Target_type, 258 typename Relocate, 259 typename Relocate_comdat_behavior, 260 typename Classify_reloc> 261 inline void 262 relocate_section( 263 const Relocate_info<size, big_endian>* relinfo, 264 Target_type* target, 265 const unsigned char* prelocs, 266 size_t reloc_count, 267 Output_section* output_section, 268 bool needs_special_offset_handling, 269 unsigned char* view, 270 typename elfcpp::Elf_types<size>::Elf_Addr view_address, 271 section_size_type view_size, 272 const Reloc_symbol_changes* reloc_symbol_changes) 273 { 274 typedef typename Classify_reloc::Reltype Reltype; 275 const int reloc_size = Classify_reloc::reloc_size; 276 Relocate relocate; 277 Relocate_comdat_behavior relocate_comdat_behavior; 278 279 Sized_relobj_file<size, big_endian>* object = relinfo->object; 280 unsigned int local_count = object->local_symbol_count(); 281 282 Comdat_behavior comdat_behavior = CB_UNDETERMINED; 283 284 for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size) 285 { 286 Reltype reloc(prelocs); 287 288 section_offset_type offset = 289 convert_to_section_size_type(reloc.get_r_offset()); 290 291 if (needs_special_offset_handling) 292 { 293 offset = output_section->output_offset(relinfo->object, 294 relinfo->data_shndx, 295 offset); 296 if (offset == -1) 297 continue; 298 } 299 300 unsigned int r_sym = Classify_reloc::get_r_sym(&reloc); 301 302 const Sized_symbol<size>* sym; 303 304 Symbol_value<size> symval; 305 const Symbol_value<size> *psymval; 306 bool is_defined_in_discarded_section; 307 unsigned int shndx; 308 if (r_sym < local_count 309 && (reloc_symbol_changes == NULL 310 || (*reloc_symbol_changes)[i] == NULL)) 311 { 312 sym = NULL; 313 psymval = object->local_symbol(r_sym); 314 315 // If the local symbol belongs to a section we are discarding, 316 // and that section is a debug section, try to find the 317 // corresponding kept section and map this symbol to its 318 // counterpart in the kept section. The symbol must not 319 // correspond to a section we are folding. 320 bool is_ordinary; 321 shndx = psymval->input_shndx(&is_ordinary); 322 is_defined_in_discarded_section = 323 (is_ordinary 324 && shndx != elfcpp::SHN_UNDEF 325 && !object->is_section_included(shndx) 326 && !relinfo->symtab->is_section_folded(object, shndx)); 327 } 328 else 329 { 330 const Symbol* gsym; 331 if (reloc_symbol_changes != NULL 332 && (*reloc_symbol_changes)[i] != NULL) 333 gsym = (*reloc_symbol_changes)[i]; 334 else 335 { 336 gsym = object->global_symbol(r_sym); 337 gold_assert(gsym != NULL); 338 if (gsym->is_forwarder()) 339 gsym = relinfo->symtab->resolve_forwards(gsym); 340 } 341 342 sym = static_cast<const Sized_symbol<size>*>(gsym); 343 if (sym->has_symtab_index() && sym->symtab_index() != -1U) 344 symval.set_output_symtab_index(sym->symtab_index()); 345 else 346 symval.set_no_output_symtab_entry(); 347 symval.set_output_value(sym->value()); 348 if (gsym->type() == elfcpp::STT_TLS) 349 symval.set_is_tls_symbol(); 350 else if (gsym->type() == elfcpp::STT_GNU_IFUNC) 351 symval.set_is_ifunc_symbol(); 352 psymval = &symval; 353 354 is_defined_in_discarded_section = 355 (gsym->is_defined_in_discarded_section() 356 && gsym->is_undefined()); 357 shndx = 0; 358 } 359 360 Symbol_value<size> symval2; 361 if (is_defined_in_discarded_section) 362 { 363 if (comdat_behavior == CB_UNDETERMINED) 364 { 365 std::string name = object->section_name(relinfo->data_shndx); 366 comdat_behavior = relocate_comdat_behavior.get(name.c_str()); 367 } 368 if (comdat_behavior == CB_PRETEND) 369 { 370 // FIXME: This case does not work for global symbols. 371 // We have no place to store the original section index. 372 // Fortunately this does not matter for comdat sections, 373 // only for sections explicitly discarded by a linker 374 // script. 375 bool found; 376 typename elfcpp::Elf_types<size>::Elf_Addr value = 377 object->map_to_kept_section(shndx, &found); 378 if (found) 379 symval2.set_output_value(value + psymval->input_value()); 380 else 381 symval2.set_output_value(0); 382 } 383 else 384 { 385 if (comdat_behavior == CB_WARNING) 386 gold_warning_at_location(relinfo, i, offset, 387 _("relocation refers to discarded " 388 "section")); 389 symval2.set_output_value(0); 390 } 391 symval2.set_no_output_symtab_entry(); 392 psymval = &symval2; 393 } 394 395 // If OFFSET is out of range, still let the target decide to 396 // ignore the relocation. Pass in NULL as the VIEW argument so 397 // that it can return quickly without trashing an invalid memory 398 // address. 399 unsigned char *v = view + offset; 400 if (offset < 0 || static_cast<section_size_type>(offset) >= view_size) 401 v = NULL; 402 403 if (!relocate.relocate(relinfo, Classify_reloc::sh_type, target, 404 output_section, i, prelocs, sym, psymval, 405 v, view_address + offset, view_size)) 406 continue; 407 408 if (v == NULL) 409 { 410 gold_error_at_location(relinfo, i, offset, 411 _("reloc has bad offset %zu"), 412 static_cast<size_t>(offset)); 413 continue; 414 } 415 416 if (issue_undefined_symbol_error(sym)) 417 gold_undefined_symbol_at_location(sym, relinfo, i, offset); 418 else if (sym != NULL 419 && sym->visibility() != elfcpp::STV_DEFAULT 420 && (sym->is_strong_undefined() || sym->is_from_dynobj())) 421 visibility_error(sym); 422 423 if (sym != NULL && sym->has_warning()) 424 relinfo->symtab->issue_warning(sym, relinfo, i, offset); 425 } 426 } 427 428 // Apply an incremental relocation. 429 430 template<int size, bool big_endian, typename Target_type, 431 typename Relocate> 432 void 433 apply_relocation(const Relocate_info<size, big_endian>* relinfo, 434 Target_type* target, 435 typename elfcpp::Elf_types<size>::Elf_Addr r_offset, 436 unsigned int r_type, 437 typename elfcpp::Elf_types<size>::Elf_Swxword r_addend, 438 const Symbol* gsym, 439 unsigned char* view, 440 typename elfcpp::Elf_types<size>::Elf_Addr address, 441 section_size_type view_size) 442 { 443 // Construct the ELF relocation in a temporary buffer. 444 const int reloc_size = elfcpp::Elf_sizes<size>::rela_size; 445 unsigned char relbuf[reloc_size]; 446 elfcpp::Rela_write<size, big_endian> orel(relbuf); 447 orel.put_r_offset(r_offset); 448 orel.put_r_info(elfcpp::elf_r_info<size>(0, r_type)); 449 orel.put_r_addend(r_addend); 450 451 // Setup a Symbol_value for the global symbol. 452 const Sized_symbol<size>* sym = static_cast<const Sized_symbol<size>*>(gsym); 453 Symbol_value<size> symval; 454 gold_assert(sym->has_symtab_index() && sym->symtab_index() != -1U); 455 symval.set_output_symtab_index(sym->symtab_index()); 456 symval.set_output_value(sym->value()); 457 if (gsym->type() == elfcpp::STT_TLS) 458 symval.set_is_tls_symbol(); 459 else if (gsym->type() == elfcpp::STT_GNU_IFUNC) 460 symval.set_is_ifunc_symbol(); 461 462 Relocate relocate; 463 relocate.relocate(relinfo, elfcpp::SHT_RELA, target, NULL, 464 -1U, relbuf, sym, &symval, 465 view + r_offset, address + r_offset, view_size); 466 } 467 468 // A class for inquiring about properties of a relocation, 469 // used while scanning relocs during a relocatable link and 470 // garbage collection. This class may be used as the default 471 // for SHT_RELA targets, but SHT_REL targets must implement 472 // a derived class that overrides get_size_for_reloc. 473 // The MIPS-64 target also needs to override the methods 474 // for accessing the r_sym and r_type fields of a relocation, 475 // due to its non-standard use of the r_info field. 476 477 template<int sh_type_, int size, bool big_endian> 478 class Default_classify_reloc 479 { 480 public: 481 typedef typename Reloc_types<sh_type_, size, big_endian>::Reloc 482 Reltype; 483 typedef typename Reloc_types<sh_type_, size, big_endian>::Reloc_write 484 Reltype_write; 485 static const int reloc_size = 486 Reloc_types<sh_type_, size, big_endian>::reloc_size; 487 static const int sh_type = sh_type_; 488 489 // Return the symbol referred to by the relocation. 490 static inline unsigned int 491 get_r_sym(const Reltype* reloc) 492 { return elfcpp::elf_r_sym<size>(reloc->get_r_info()); } 493 494 // Return the type of the relocation. 495 static inline unsigned int 496 get_r_type(const Reltype* reloc) 497 { return elfcpp::elf_r_type<size>(reloc->get_r_info()); } 498 499 // Return the explicit addend of the relocation (return 0 for SHT_REL). 500 static inline typename elfcpp::Elf_types<size>::Elf_Swxword 501 get_r_addend(const Reltype* reloc) 502 { return Reloc_types<sh_type_, size, big_endian>::get_reloc_addend(reloc); } 503 504 // Write the r_info field to a new reloc, using the r_info field from 505 // the original reloc, replacing the r_sym field with R_SYM. 506 static inline void 507 put_r_info(Reltype_write* new_reloc, Reltype* reloc, unsigned int r_sym) 508 { 509 unsigned int r_type = elfcpp::elf_r_type<size>(reloc->get_r_info()); 510 new_reloc->put_r_info(elfcpp::elf_r_info<size>(r_sym, r_type)); 511 } 512 513 // Write the r_addend field to a new reloc. 514 static inline void 515 put_r_addend(Reltype_write* to, 516 typename elfcpp::Elf_types<size>::Elf_Swxword addend) 517 { Reloc_types<sh_type_, size, big_endian>::set_reloc_addend(to, addend); } 518 519 // Return the size of the addend of the relocation (only used for SHT_REL). 520 static unsigned int 521 get_size_for_reloc(unsigned int, Relobj*) 522 { 523 gold_unreachable(); 524 return 0; 525 } 526 }; 527 528 // This class may be used as a typical class for the 529 // Scan_relocatable_reloc parameter to scan_relocatable_relocs. 530 // This class is intended to capture the most typical target behaviour, 531 // while still permitting targets to define their own independent class 532 // for Scan_relocatable_reloc. 533 534 template<typename Classify_reloc> 535 class Default_scan_relocatable_relocs 536 { 537 public: 538 typedef typename Classify_reloc::Reltype Reltype; 539 static const int reloc_size = Classify_reloc::reloc_size; 540 static const int sh_type = Classify_reloc::sh_type; 541 542 // Return the symbol referred to by the relocation. 543 static inline unsigned int 544 get_r_sym(const Reltype* reloc) 545 { return Classify_reloc::get_r_sym(reloc); } 546 547 // Return the type of the relocation. 548 static inline unsigned int 549 get_r_type(const Reltype* reloc) 550 { return Classify_reloc::get_r_type(reloc); } 551 552 // Return the strategy to use for a local symbol which is not a 553 // section symbol, given the relocation type. 554 inline Relocatable_relocs::Reloc_strategy 555 local_non_section_strategy(unsigned int r_type, Relobj*, unsigned int r_sym) 556 { 557 // We assume that relocation type 0 is NONE. Targets which are 558 // different must override. 559 if (r_type == 0 && r_sym == 0) 560 return Relocatable_relocs::RELOC_DISCARD; 561 return Relocatable_relocs::RELOC_COPY; 562 } 563 564 // Return the strategy to use for a local symbol which is a section 565 // symbol, given the relocation type. 566 inline Relocatable_relocs::Reloc_strategy 567 local_section_strategy(unsigned int r_type, Relobj* object) 568 { 569 if (sh_type == elfcpp::SHT_RELA) 570 return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA; 571 else 572 { 573 switch (Classify_reloc::get_size_for_reloc(r_type, object)) 574 { 575 case 0: 576 return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0; 577 case 1: 578 return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1; 579 case 2: 580 return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2; 581 case 4: 582 return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4; 583 case 8: 584 return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8; 585 default: 586 gold_unreachable(); 587 } 588 } 589 } 590 591 // Return the strategy to use for a global symbol, given the 592 // relocation type, the object, and the symbol index. 593 inline Relocatable_relocs::Reloc_strategy 594 global_strategy(unsigned int, Relobj*, unsigned int) 595 { return Relocatable_relocs::RELOC_COPY; } 596 }; 597 598 // This is a strategy class used with scan_relocatable_relocs 599 // and --emit-relocs. 600 601 template<typename Classify_reloc> 602 class Default_emit_relocs_strategy 603 { 604 public: 605 typedef typename Classify_reloc::Reltype Reltype; 606 static const int reloc_size = Classify_reloc::reloc_size; 607 static const int sh_type = Classify_reloc::sh_type; 608 609 // Return the symbol referred to by the relocation. 610 static inline unsigned int 611 get_r_sym(const Reltype* reloc) 612 { return Classify_reloc::get_r_sym(reloc); } 613 614 // Return the type of the relocation. 615 static inline unsigned int 616 get_r_type(const Reltype* reloc) 617 { return Classify_reloc::get_r_type(reloc); } 618 619 // A local non-section symbol. 620 inline Relocatable_relocs::Reloc_strategy 621 local_non_section_strategy(unsigned int, Relobj*, unsigned int) 622 { return Relocatable_relocs::RELOC_COPY; } 623 624 // A local section symbol. 625 inline Relocatable_relocs::Reloc_strategy 626 local_section_strategy(unsigned int, Relobj*) 627 { 628 if (sh_type == elfcpp::SHT_RELA) 629 return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA; 630 else 631 { 632 // The addend is stored in the section contents. Since this 633 // is not a relocatable link, we are going to apply the 634 // relocation contents to the section as usual. This means 635 // that we have no way to record the original addend. If the 636 // original addend is not zero, there is basically no way for 637 // the user to handle this correctly. Caveat emptor. 638 return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0; 639 } 640 } 641 642 // A global symbol. 643 inline Relocatable_relocs::Reloc_strategy 644 global_strategy(unsigned int, Relobj*, unsigned int) 645 { return Relocatable_relocs::RELOC_COPY; } 646 }; 647 648 // Scan relocs during a relocatable link. This is a default 649 // definition which should work for most targets. 650 // Scan_relocatable_reloc must name a class type which provides three 651 // functions which return a Relocatable_relocs::Reloc_strategy code: 652 // global_strategy, local_non_section_strategy, and 653 // local_section_strategy. Most targets should be able to use 654 // Default_scan_relocatable_relocs as this class. 655 656 template<int size, bool big_endian, typename Scan_relocatable_reloc> 657 void 658 scan_relocatable_relocs( 659 Symbol_table*, 660 Layout*, 661 Sized_relobj_file<size, big_endian>* object, 662 unsigned int data_shndx, 663 const unsigned char* prelocs, 664 size_t reloc_count, 665 Output_section* output_section, 666 bool needs_special_offset_handling, 667 size_t local_symbol_count, 668 const unsigned char* plocal_syms, 669 Relocatable_relocs* rr) 670 { 671 typedef typename Scan_relocatable_reloc::Reltype Reltype; 672 const int reloc_size = Scan_relocatable_reloc::reloc_size; 673 const int sym_size = elfcpp::Elf_sizes<size>::sym_size; 674 Scan_relocatable_reloc scan; 675 676 for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size) 677 { 678 Reltype reloc(prelocs); 679 680 Relocatable_relocs::Reloc_strategy strategy; 681 682 if (needs_special_offset_handling 683 && !output_section->is_input_address_mapped(object, data_shndx, 684 reloc.get_r_offset())) 685 strategy = Relocatable_relocs::RELOC_DISCARD; 686 else 687 { 688 const unsigned int r_sym = Scan_relocatable_reloc::get_r_sym(&reloc); 689 const unsigned int r_type = 690 Scan_relocatable_reloc::get_r_type(&reloc); 691 692 if (r_sym >= local_symbol_count) 693 strategy = scan.global_strategy(r_type, object, r_sym); 694 else 695 { 696 gold_assert(plocal_syms != NULL); 697 typename elfcpp::Sym<size, big_endian> lsym(plocal_syms 698 + r_sym * sym_size); 699 unsigned int shndx = lsym.get_st_shndx(); 700 bool is_ordinary; 701 shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary); 702 if (is_ordinary 703 && shndx != elfcpp::SHN_UNDEF 704 && !object->is_section_included(shndx)) 705 { 706 // RELOC is a relocation against a local symbol 707 // defined in a section we are discarding. Discard 708 // the reloc. FIXME: Should we issue a warning? 709 strategy = Relocatable_relocs::RELOC_DISCARD; 710 } 711 else if (lsym.get_st_type() != elfcpp::STT_SECTION) 712 strategy = scan.local_non_section_strategy(r_type, object, 713 r_sym); 714 else 715 { 716 strategy = scan.local_section_strategy(r_type, object); 717 if (strategy != Relocatable_relocs::RELOC_DISCARD) 718 object->output_section(shndx)->set_needs_symtab_index(); 719 } 720 721 if (strategy == Relocatable_relocs::RELOC_COPY) 722 object->set_must_have_output_symtab_entry(r_sym); 723 } 724 } 725 726 rr->set_next_reloc_strategy(strategy); 727 } 728 } 729 730 // Relocate relocs. Called for a relocatable link, and for --emit-relocs. 731 // This is a default definition which should work for most targets. 732 733 template<int size, bool big_endian, typename Classify_reloc> 734 void 735 relocate_relocs( 736 const Relocate_info<size, big_endian>* relinfo, 737 const unsigned char* prelocs, 738 size_t reloc_count, 739 Output_section* output_section, 740 typename elfcpp::Elf_types<size>::Elf_Off offset_in_output_section, 741 unsigned char* view, 742 typename elfcpp::Elf_types<size>::Elf_Addr view_address, 743 section_size_type view_size, 744 unsigned char* reloc_view, 745 section_size_type reloc_view_size) 746 { 747 typedef typename elfcpp::Elf_types<size>::Elf_Addr Address; 748 typedef typename Classify_reloc::Reltype Reltype; 749 typedef typename Classify_reloc::Reltype_write Reltype_write; 750 const int reloc_size = Classify_reloc::reloc_size; 751 const Address invalid_address = static_cast<Address>(0) - 1; 752 753 Sized_relobj_file<size, big_endian>* const object = relinfo->object; 754 const unsigned int local_count = object->local_symbol_count(); 755 756 unsigned char* pwrite = reloc_view; 757 758 for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size) 759 { 760 Relocatable_relocs::Reloc_strategy strategy = relinfo->rr->strategy(i); 761 if (strategy == Relocatable_relocs::RELOC_DISCARD) 762 continue; 763 764 if (strategy == Relocatable_relocs::RELOC_SPECIAL) 765 { 766 // Target wants to handle this relocation. 767 Sized_target<size, big_endian>* target = 768 parameters->sized_target<size, big_endian>(); 769 target->relocate_special_relocatable(relinfo, Classify_reloc::sh_type, 770 prelocs, i, output_section, 771 offset_in_output_section, 772 view, view_address, 773 view_size, pwrite); 774 pwrite += reloc_size; 775 continue; 776 } 777 Reltype reloc(prelocs); 778 Reltype_write reloc_write(pwrite); 779 780 const unsigned int r_sym = Classify_reloc::get_r_sym(&reloc); 781 782 // Get the new symbol index. 783 784 Output_section* os = NULL; 785 unsigned int new_symndx; 786 if (r_sym < local_count) 787 { 788 switch (strategy) 789 { 790 case Relocatable_relocs::RELOC_COPY: 791 if (r_sym == 0) 792 new_symndx = 0; 793 else 794 { 795 new_symndx = object->symtab_index(r_sym); 796 gold_assert(new_symndx != -1U); 797 } 798 break; 799 800 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA: 801 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0: 802 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1: 803 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2: 804 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4: 805 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8: 806 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4_UNALIGNED: 807 { 808 // We are adjusting a section symbol. We need to find 809 // the symbol table index of the section symbol for 810 // the output section corresponding to input section 811 // in which this symbol is defined. 812 gold_assert(r_sym < local_count); 813 bool is_ordinary; 814 unsigned int shndx = 815 object->local_symbol_input_shndx(r_sym, &is_ordinary); 816 gold_assert(is_ordinary); 817 os = object->output_section(shndx); 818 gold_assert(os != NULL); 819 gold_assert(os->needs_symtab_index()); 820 new_symndx = os->symtab_index(); 821 } 822 break; 823 824 default: 825 gold_unreachable(); 826 } 827 } 828 else 829 { 830 const Symbol* gsym = object->global_symbol(r_sym); 831 gold_assert(gsym != NULL); 832 if (gsym->is_forwarder()) 833 gsym = relinfo->symtab->resolve_forwards(gsym); 834 835 gold_assert(gsym->has_symtab_index()); 836 new_symndx = gsym->symtab_index(); 837 } 838 839 // Get the new offset--the location in the output section where 840 // this relocation should be applied. 841 842 Address offset = reloc.get_r_offset(); 843 Address new_offset; 844 if (offset_in_output_section != invalid_address) 845 new_offset = offset + offset_in_output_section; 846 else 847 { 848 section_offset_type sot_offset = 849 convert_types<section_offset_type, Address>(offset); 850 section_offset_type new_sot_offset = 851 output_section->output_offset(object, relinfo->data_shndx, 852 sot_offset); 853 gold_assert(new_sot_offset != -1); 854 new_offset = new_sot_offset; 855 } 856 857 // In an object file, r_offset is an offset within the section. 858 // In an executable or dynamic object, generated by 859 // --emit-relocs, r_offset is an absolute address. 860 if (!parameters->options().relocatable()) 861 { 862 new_offset += view_address; 863 if (offset_in_output_section != invalid_address) 864 new_offset -= offset_in_output_section; 865 } 866 867 reloc_write.put_r_offset(new_offset); 868 Classify_reloc::put_r_info(&reloc_write, &reloc, new_symndx); 869 870 // Handle the reloc addend based on the strategy. 871 872 if (strategy == Relocatable_relocs::RELOC_COPY) 873 { 874 if (Classify_reloc::sh_type == elfcpp::SHT_RELA) 875 Classify_reloc::put_r_addend(&reloc_write, 876 Classify_reloc::get_r_addend(&reloc)); 877 } 878 else 879 { 880 // The relocation uses a section symbol in the input file. 881 // We are adjusting it to use a section symbol in the output 882 // file. The input section symbol refers to some address in 883 // the input section. We need the relocation in the output 884 // file to refer to that same address. This adjustment to 885 // the addend is the same calculation we use for a simple 886 // absolute relocation for the input section symbol. 887 888 const Symbol_value<size>* psymval = object->local_symbol(r_sym); 889 890 unsigned char* padd = view + offset; 891 switch (strategy) 892 { 893 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA: 894 { 895 typename elfcpp::Elf_types<size>::Elf_Swxword addend; 896 addend = Classify_reloc::get_r_addend(&reloc); 897 gold_assert(os != NULL); 898 addend = psymval->value(object, addend) - os->address(); 899 Classify_reloc::put_r_addend(&reloc_write, addend); 900 } 901 break; 902 903 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0: 904 break; 905 906 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1: 907 Relocate_functions<size, big_endian>::rel8(padd, object, 908 psymval); 909 break; 910 911 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2: 912 Relocate_functions<size, big_endian>::rel16(padd, object, 913 psymval); 914 break; 915 916 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4: 917 Relocate_functions<size, big_endian>::rel32(padd, object, 918 psymval); 919 break; 920 921 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8: 922 Relocate_functions<size, big_endian>::rel64(padd, object, 923 psymval); 924 break; 925 926 case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4_UNALIGNED: 927 Relocate_functions<size, big_endian>::rel32_unaligned(padd, 928 object, 929 psymval); 930 break; 931 932 default: 933 gold_unreachable(); 934 } 935 } 936 937 pwrite += reloc_size; 938 } 939 940 gold_assert(static_cast<section_size_type>(pwrite - reloc_view) 941 == reloc_view_size); 942 } 943 944 } // End namespace gold. 945 946 #endif // !defined(GOLD_TARGET_RELOC_H) 947
