gold/reloc.cc

   1 // reloc.cc -- relocate input files for gold.
   2
   3 // Copyright 2006, 2007 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@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 #include "gold.h"
  24
  25 #include "workqueue.h"
  26 #include "symtab.h"
  27 #include "output.h"
  28 #include "merge.h"
  29 #include "object.h"
  30 #include "reloc.h"
  31
  32 namespace gold
  33 {
  34
  35 // Read_relocs methods.
  36
  37 // These tasks just read the relocation information from the file.
  38 // After reading it, the start another task to process the
  39 // information.  These tasks requires access to the file.
  40
  41 Task_token*
  42 Read_relocs::is_runnable()
  43 {
  44   return this->object_->is_locked() ? this->object_->token() : NULL;
  45 }
  46
  47 // Lock the file.
  48
  49 void
  50 Read_relocs::locks(Task_locker* tl)
  51 {
  52   tl->add(this, this->object_->token());
  53 }
  54
  55 // Read the relocations and then start a Scan_relocs_task.
  56
  57 void
  58 Read_relocs::run(Workqueue* workqueue)
  59 {
  60   Read_relocs_data *rd = new Read_relocs_data;
  61   this->object_->read_relocs(rd);
  62   this->object_->release();
  63
  64   workqueue->queue_front(new Scan_relocs(this->options_, this->symtab_,
  65                                          this->layout_, this->object_, rd,
  66                                          this->symtab_lock_, this->blocker_));
  67 }
  68
  69 // Return a debugging name for the task.
  70
  71 std::string
  72 Read_relocs::get_name() const
  73 {
  74   return "Read_relocs " + this->object_->name();
  75 }
  76
  77 // Scan_relocs methods.
  78
  79 // These tasks scan the relocations read by Read_relocs and mark up
  80 // the symbol table to indicate which relocations are required.  We
  81 // use a lock on the symbol table to keep them from interfering with
  82 // each other.
  83
  84 Task_token*
  85 Scan_relocs::is_runnable()
  86 {
  87   if (!this->symtab_lock_->is_writable())
  88     return this->symtab_lock_;
  89   if (this->object_->is_locked())
  90     return this->object_->token();
  91   return NULL;
  92 }
  93
  94 // Return the locks we hold: one on the file, one on the symbol table
  95 // and one blocker.
  96
  97 void
  98 Scan_relocs::locks(Task_locker* tl)
  99 {
 100   tl->add(this, this->object_->token());
 101   tl->add(this, this->symtab_lock_);
 102   tl->add(this, this->blocker_);
 103 }
 104
 105 // Scan the relocs.
 106
 107 void
 108 Scan_relocs::run(Workqueue*)
 109 {
 110   this->object_->scan_relocs(this->options_, this->symtab_, this->layout_,
 111                              this->rd_);
 112   this->object_->release();
 113   delete this->rd_;
 114   this->rd_ = NULL;
 115 }
 116
 117 // Return a debugging name for the task.
 118
 119 std::string
 120 Scan_relocs::get_name() const
 121 {
 122   return "Scan_relocs " + this->object_->name();
 123 }
 124
 125 // Relocate_task methods.
 126
 127 // We may have to wait for the output sections to be written.
 128
 129 Task_token*
 130 Relocate_task::is_runnable()
 131 {
 132   if (this->object_->relocs_must_follow_section_writes()
 133       && this->output_sections_blocker_->is_blocked())
 134     return this->output_sections_blocker_;
 135
 136   if (this->object_->is_locked())
 137     return this->object_->token();
 138
 139   return NULL;
 140 }
 141
 142 // We want to lock the file while we run.  We want to unblock
 143 // INPUT_SECTIONS_BLOCKER and FINAL_BLOCKER when we are done.
 144 // INPUT_SECTIONS_BLOCKER may be NULL.
 145
 146 void
 147 Relocate_task::locks(Task_locker* tl)
 148 {
 149   if (this->input_sections_blocker_ != NULL)
 150     tl->add(this, this->input_sections_blocker_);
 151   tl->add(this, this->final_blocker_);
 152   tl->add(this, this->object_->token());
 153 }
 154
 155 // Run the task.
 156
 157 void
 158 Relocate_task::run(Workqueue*)
 159 {
 160   this->object_->relocate(this->options_, this->symtab_, this->layout_,
 161                           this->of_);
 162   this->object_->release();
 163 }
 164
 165 // Return a debugging name for the task.
 166
 167 std::string
 168 Relocate_task::get_name() const
 169 {
 170   return "Relocate_task " + this->object_->name();
 171 }
 172
 173 // Read the relocs and local symbols from the object file and store
 174 // the information in RD.
 175
 176 template<int size, bool big_endian>
 177 void
 178 Sized_relobj<size, big_endian>::do_read_relocs(Read_relocs_data* rd)
 179 {
 180   rd->relocs.clear();
 181
 182   unsigned int shnum = this->shnum();
 183   if (shnum == 0)
 184     return;
 185
 186   rd->relocs.reserve(shnum / 2);
 187
 188   std::vector<Map_to_output>& map_sections(this->map_to_output());
 189
 190   const unsigned char *pshdrs = this->get_view(this->elf_file_.shoff(),
 191                                                shnum * This::shdr_size,
 192                                                true);
 193   // Skip the first, dummy, section.
 194   const unsigned char *ps = pshdrs + This::shdr_size;
 195   for (unsigned int i = 1; i < shnum; ++i, ps += This::shdr_size)
 196     {
 197       typename This::Shdr shdr(ps);
 198
 199       unsigned int sh_type = shdr.get_sh_type();
 200       if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
 201         continue;
 202
 203       unsigned int shndx = shdr.get_sh_info();
 204       if (shndx >= shnum)
 205         {
 206           this->error(_("relocation section %u has bad info %u"),
 207                       i, shndx);
 208           continue;
 209         }
 210
 211       Output_section* os = map_sections[shndx].output_section;
 212       if (os == NULL)
 213         continue;
 214
 215       // We are scanning relocations in order to fill out the GOT and
 216       // PLT sections.  Relocations for sections which are not
 217       // allocated (typically debugging sections) should not add new
 218       // GOT and PLT entries.  So we skip them.
 219       typename This::Shdr secshdr(pshdrs + shndx * This::shdr_size);
 220       if ((secshdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
 221         continue;
 222
 223       if (shdr.get_sh_link() != this->symtab_shndx_)
 224         {
 225           this->error(_("relocation section %u uses unexpected "
 226                         "symbol table %u"),
 227                       i, shdr.get_sh_link());
 228           continue;
 229         }
 230
 231       off_t sh_size = shdr.get_sh_size();
 232
 233       unsigned int reloc_size;
 234       if (sh_type == elfcpp::SHT_REL)
 235         reloc_size = elfcpp::Elf_sizes<size>::rel_size;
 236       else
 237         reloc_size = elfcpp::Elf_sizes<size>::rela_size;
 238       if (reloc_size != shdr.get_sh_entsize())
 239         {
 240           this->error(_("unexpected entsize for reloc section %u: %lu != %u"),
 241                       i, static_cast<unsigned long>(shdr.get_sh_entsize()),
 242                       reloc_size);
 243           continue;
 244         }
 245
 246       size_t reloc_count = sh_size / reloc_size;
 247       if (static_cast<off_t>(reloc_count * reloc_size) != sh_size)
 248         {
 249           this->error(_("reloc section %u size %lu uneven"),
 250                       i, static_cast<unsigned long>(sh_size));
 251           continue;
 252         }
 253
 254       rd->relocs.push_back(Section_relocs());
 255       Section_relocs& sr(rd->relocs.back());
 256       sr.reloc_shndx = i;
 257       sr.data_shndx = shndx;
 258       sr.contents = this->get_lasting_view(shdr.get_sh_offset(), sh_size,
 259                                            true);
 260       sr.sh_type = sh_type;
 261       sr.reloc_count = reloc_count;
 262       sr.output_section = os;
 263       sr.needs_special_offset_handling = map_sections[shndx].offset == -1;
 264     }
 265
 266   // Read the local symbols.
 267   gold_assert(this->symtab_shndx_ != -1U);
 268   if (this->symtab_shndx_ == 0 || this->local_symbol_count_ == 0)
 269     rd->local_symbols = NULL;
 270   else
 271     {
 272       typename This::Shdr symtabshdr(pshdrs
 273                                      + this->symtab_shndx_ * This::shdr_size);
 274       gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
 275       const int sym_size = This::sym_size;
 276       const unsigned int loccount = this->local_symbol_count_;
 277       gold_assert(loccount == symtabshdr.get_sh_info());
 278       off_t locsize = loccount * sym_size;
 279       rd->local_symbols = this->get_lasting_view(symtabshdr.get_sh_offset(),
 280                                                  locsize, true);
 281     }
 282 }
 283
 284 // Scan the relocs and adjust the symbol table.  This looks for
 285 // relocations which require GOT/PLT/COPY relocations.
 286
 287 template<int size, bool big_endian>
 288 void
 289 Sized_relobj<size, big_endian>::do_scan_relocs(const General_options& options,
 290                                                Symbol_table* symtab,
 291                                                Layout* layout,
 292                                                Read_relocs_data* rd)
 293 {
 294   Sized_target<size, big_endian>* target = this->sized_target();
 295
 296   const unsigned char* local_symbols;
 297   if (rd->local_symbols == NULL)
 298     local_symbols = NULL;
 299   else
 300     local_symbols = rd->local_symbols->data();
 301
 302   for (Read_relocs_data::Relocs_list::iterator p = rd->relocs.begin();
 303        p != rd->relocs.end();
 304        ++p)
 305     {
 306       target->scan_relocs(options, symtab, layout, this, p->data_shndx,
 307                           p->sh_type, p->contents->data(), p->reloc_count,
 308                           p->output_section, p->needs_special_offset_handling,
 309                           this->local_symbol_count_,
 310                           local_symbols);
 311       delete p->contents;
 312       p->contents = NULL;
 313     }
 314
 315   if (rd->local_symbols != NULL)
 316     {
 317       delete rd->local_symbols;
 318       rd->local_symbols = NULL;
 319     }
 320 }
 321
 322 // Relocate the input sections and write out the local symbols.
 323
 324 template<int size, bool big_endian>
 325 void
 326 Sized_relobj<size, big_endian>::do_relocate(const General_options& options,
 327                                             const Symbol_table* symtab,
 328                                             const Layout* layout,
 329                                             Output_file* of)
 330 {
 331   unsigned int shnum = this->shnum();
 332
 333   // Read the section headers.
 334   const unsigned char* pshdrs = this->get_view(this->elf_file_.shoff(),
 335                                                shnum * This::shdr_size,
 336                                                true);
 337
 338   Views views;
 339   views.resize(shnum);
 340
 341   // Make two passes over the sections.  The first one copies the
 342   // section data to the output file.  The second one applies
 343   // relocations.
 344
 345   this->write_sections(pshdrs, of, &views);
 346
 347   // To speed up relocations, we set up hash tables for fast lookup of
 348   // input offsets to output addresses.
 349   this->initialize_input_to_output_maps();
 350
 351   // Apply relocations.
 352
 353   this->relocate_sections(options, symtab, layout, pshdrs, &views);
 354
 355   // After we've done the relocations, we release the hash tables,
 356   // since we no longer need them.
 357   this->free_input_to_output_maps();
 358
 359   // Write out the accumulated views.
 360   for (unsigned int i = 1; i < shnum; ++i)
 361     {
 362       if (views[i].view != NULL)
 363         {
 364           if (!views[i].is_postprocessing_view)
 365             {
 366               if (views[i].is_input_output_view)
 367                 of->write_input_output_view(views[i].offset,
 368                                             views[i].view_size,
 369                                             views[i].view);
 370               else
 371                 of->write_output_view(views[i].offset, views[i].view_size,
 372                                       views[i].view);
 373             }
 374         }
 375     }
 376
 377   // Write out the local symbols.
 378   this->write_local_symbols(of, layout->sympool(), layout->dynpool());
 379 }
 380
 381 // Write section data to the output file.  PSHDRS points to the
 382 // section headers.  Record the views in *PVIEWS for use when
 383 // relocating.
 384
 385 template<int size, bool big_endian>
 386 void
 387 Sized_relobj<size, big_endian>::write_sections(const unsigned char* pshdrs,
 388                                                Output_file* of,
 389                                                Views* pviews) const
 390 {
 391   unsigned int shnum = this->shnum();
 392   const std::vector<Map_to_output>& map_sections(this->map_to_output());
 393
 394   const unsigned char* p = pshdrs + This::shdr_size;
 395   for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
 396     {
 397       View_size* pvs = &(*pviews)[i];
 398
 399       pvs->view = NULL;
 400
 401       const Output_section* os = map_sections[i].output_section;
 402       if (os == NULL)
 403         continue;
 404       off_t output_offset = map_sections[i].offset;
 405
 406       typename This::Shdr shdr(p);
 407
 408       if (shdr.get_sh_type() == elfcpp::SHT_NOBITS)
 409         continue;
 410
 411       // In the normal case, this input section is simply mapped to
 412       // the output section at offset OUTPUT_OFFSET.
 413
 414       // However, if OUTPUT_OFFSET == -1, then input data is handled
 415       // specially--e.g., a .eh_frame section.  The relocation
 416       // routines need to check for each reloc where it should be
 417       // applied.  For this case, we need an input/output view for the
 418       // entire contents of the section in the output file.  We don't
 419       // want to copy the contents of the input section to the output
 420       // section; the output section contents were already written,
 421       // and we waited for them in Relocate_task::is_runnable because
 422       // relocs_must_follow_section_writes is set for the object.
 423
 424       // Regardless of which of the above cases is true, we have to
 425       // check requires_postprocessing of the output section.  If that
 426       // is false, then we work with views of the output file
 427       // directly.  If it is true, then we work with a separate
 428       // buffer, and the output section is responsible for writing the
 429       // final data to the output file.
 430
 431       off_t output_section_offset;
 432       off_t output_section_size;
 433       if (!os->requires_postprocessing())
 434         {
 435           output_section_offset = os->offset();
 436           output_section_size = os->data_size();
 437         }
 438       else
 439         {
 440           output_section_offset = 0;
 441           output_section_size = os->postprocessing_buffer_size();
 442         }
 443
 444       off_t view_start;
 445       section_size_type view_size;
 446       if (output_offset != -1)
 447         {
 448           view_start = output_section_offset + output_offset;
 449           view_size = convert_to_section_size_type(shdr.get_sh_size());
 450         }
 451       else
 452         {
 453           view_start = output_section_offset;
 454           view_size = convert_to_section_size_type(output_section_size);
 455         }
 456
 457       if (view_size == 0)
 458         continue;
 459
 460       gold_assert(output_offset == -1
 461                   || (output_offset >= 0
 462                       && (output_offset + static_cast<off_t>(view_size)
 463                           <= output_section_size)));
 464
 465       unsigned char* view;
 466       if (os->requires_postprocessing())
 467         {
 468           unsigned char* buffer = os->postprocessing_buffer();
 469           view = buffer + view_start;
 470           if (output_offset != -1)
 471             this->read(shdr.get_sh_offset(), view_size, view);
 472         }
 473       else
 474         {
 475           if (output_offset == -1)
 476             view = of->get_input_output_view(view_start, view_size);
 477           else
 478             {
 479               view = of->get_output_view(view_start, view_size);
 480               this->read(shdr.get_sh_offset(), view_size, view);
 481             }
 482         }
 483
 484       pvs->view = view;
 485       pvs->address = os->address();
 486       if (output_offset != -1)
 487         pvs->address += output_offset;
 488       pvs->offset = view_start;
 489       pvs->view_size = view_size;
 490       pvs->is_input_output_view = output_offset == -1;
 491       pvs->is_postprocessing_view = os->requires_postprocessing();
 492     }
 493 }
 494
 495 // Relocate section data.  VIEWS points to the section data as views
 496 // in the output file.
 497
 498 template<int size, bool big_endian>
 499 void
 500 Sized_relobj<size, big_endian>::relocate_sections(
 501     const General_options& options,
 502     const Symbol_table* symtab,
 503     const Layout* layout,
 504     const unsigned char* pshdrs,
 505     Views* pviews)
 506 {
 507   unsigned int shnum = this->shnum();
 508   Sized_target<size, big_endian>* target = this->sized_target();
 509
 510   const std::vector<Map_to_output>& map_sections(this->map_to_output());
 511
 512   Relocate_info<size, big_endian> relinfo;
 513   relinfo.options = &options;
 514   relinfo.symtab = symtab;
 515   relinfo.layout = layout;
 516   relinfo.object = this;
 517
 518   const unsigned char* p = pshdrs + This::shdr_size;
 519   for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
 520     {
 521       typename This::Shdr shdr(p);
 522
 523       unsigned int sh_type = shdr.get_sh_type();
 524       if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
 525         continue;
 526
 527       unsigned int index = shdr.get_sh_info();
 528       if (index >= this->shnum())
 529         {
 530           this->error(_("relocation section %u has bad info %u"),
 531                       i, index);
 532           continue;
 533         }
 534
 535       Output_section* os = map_sections[index].output_section;
 536       if (os == NULL)
 537         {
 538           // This relocation section is against a section which we
 539           // discarded.
 540           continue;
 541         }
 542       off_t output_offset = map_sections[index].offset;
 543
 544       gold_assert((*pviews)[index].view != NULL);
 545
 546       if (shdr.get_sh_link() != this->symtab_shndx_)
 547         {
 548           gold_error(_("relocation section %u uses unexpected "
 549                        "symbol table %u"),
 550                      i, shdr.get_sh_link());
 551           continue;
 552         }
 553
 554       off_t sh_size = shdr.get_sh_size();
 555       const unsigned char* prelocs = this->get_view(shdr.get_sh_offset(),
 556                                                     sh_size, false);
 557
 558       unsigned int reloc_size;
 559       if (sh_type == elfcpp::SHT_REL)
 560         reloc_size = elfcpp::Elf_sizes<size>::rel_size;
 561       else
 562         reloc_size = elfcpp::Elf_sizes<size>::rela_size;
 563
 564       if (reloc_size != shdr.get_sh_entsize())
 565         {
 566           gold_error(_("unexpected entsize for reloc section %u: %lu != %u"),
 567                      i, static_cast<unsigned long>(shdr.get_sh_entsize()),
 568                      reloc_size);
 569           continue;
 570         }
 571
 572       size_t reloc_count = sh_size / reloc_size;
 573       if (static_cast<off_t>(reloc_count * reloc_size) != sh_size)
 574         {
 575           gold_error(_("reloc section %u size %lu uneven"),
 576                      i, static_cast<unsigned long>(sh_size));
 577           continue;
 578         }
 579
 580       gold_assert(output_offset != -1
 581                   || this->relocs_must_follow_section_writes());
 582
 583       relinfo.reloc_shndx = i;
 584       relinfo.data_shndx = index;
 585       target->relocate_section(&relinfo,
 586                                sh_type,
 587                                prelocs,
 588                                reloc_count,
 589                                os,
 590                                output_offset == -1,
 591                                (*pviews)[index].view,
 592                                (*pviews)[index].address,
 593                                (*pviews)[index].view_size);
 594     }
 595 }
 596
 597 // Create merge hash tables for the local symbols.  These are used to
 598 // speed up relocations.
 599
 600 template<int size, bool big_endian>
 601 void
 602 Sized_relobj<size, big_endian>::initialize_input_to_output_maps()
 603 {
 604   const unsigned int loccount = this->local_symbol_count_;
 605   for (unsigned int i = 1; i < loccount; ++i)
 606     {
 607       Symbol_value<size>& lv(this->local_values_[i]);
 608       lv.initialize_input_to_output_map(this);
 609     }
 610 }
 611
 612 // Free merge hash tables for the local symbols.
 613
 614 template<int size, bool big_endian>
 615 void
 616 Sized_relobj<size, big_endian>::free_input_to_output_maps()
 617 {
 618   const unsigned int loccount = this->local_symbol_count_;
 619   for (unsigned int i = 1; i < loccount; ++i)
 620     {
 621       Symbol_value<size>& lv(this->local_values_[i]);
 622       lv.free_input_to_output_map();
 623     }
 624 }
 625
 626 // Class Merged_symbol_value.
 627
 628 template<int size>
 629 void
 630 Merged_symbol_value<size>::initialize_input_to_output_map(
 631     const Relobj* object,
 632     unsigned int input_shndx)
 633 {
 634   Object_merge_map* map = object->merge_map();
 635   map->initialize_input_to_output_map<size>(input_shndx,
 636                                             this->output_start_address_,
 637                                             &this->output_addresses_);
 638 }
 639
 640 // Get the output value corresponding to an input offset if we
 641 // couldn't find it in the hash table.
 642
 643 template<int size>
 644 typename elfcpp::Elf_types<size>::Elf_Addr
 645 Merged_symbol_value<size>::value_from_output_section(
 646     const Relobj* object,
 647     unsigned int input_shndx,
 648     typename elfcpp::Elf_types<size>::Elf_Addr input_offset) const
 649 {
 650   section_offset_type output_offset;
 651   bool found = object->merge_map()->get_output_offset(NULL, input_shndx,
 652                                                       input_offset,
 653                                                       &output_offset);
 654
 655   // If this assertion fails, it means that some relocation was
 656   // against a portion of an input merge section which we didn't map
 657   // to the output file and we didn't explicitly discard.  We should
 658   // always map all portions of input merge sections.
 659   gold_assert(found);
 660
 661   if (output_offset == -1)
 662     return 0;
 663   else
 664     return this->output_start_address_ + output_offset;
 665 }
 666
 667 // Copy_relocs::Copy_reloc_entry methods.
 668
 669 // Return whether we should emit this reloc.  We should emit it if the
 670 // symbol is still defined in a dynamic object.  If we should not emit
 671 // it, we clear it, to save ourselves the test next time.
 672
 673 template<int size, bool big_endian>
 674 bool
 675 Copy_relocs<size, big_endian>::Copy_reloc_entry::should_emit()
 676 {
 677   if (this->sym_ == NULL)
 678     return false;
 679   if (this->sym_->is_from_dynobj())
 680     return true;
 681   this->sym_ = NULL;
 682   return false;
 683 }
 684
 685 // Emit a reloc into a SHT_REL section.
 686
 687 template<int size, bool big_endian>
 688 void
 689 Copy_relocs<size, big_endian>::Copy_reloc_entry::emit(
 690     Output_data_reloc<elfcpp::SHT_REL, true, size, big_endian>* reloc_data)
 691 {
 692   this->sym_->set_needs_dynsym_entry();
 693   reloc_data->add_global(this->sym_, this->reloc_type_, this->output_section_,
 694                          this->relobj_, this->shndx_, this->address_);
 695 }
 696
 697 // Emit a reloc into a SHT_RELA section.
 698
 699 template<int size, bool big_endian>
 700 void
 701 Copy_relocs<size, big_endian>::Copy_reloc_entry::emit(
 702     Output_data_reloc<elfcpp::SHT_RELA, true, size, big_endian>* reloc_data)
 703 {
 704   this->sym_->set_needs_dynsym_entry();
 705   reloc_data->add_global(this->sym_, this->reloc_type_, this->output_section_,
 706                          this->relobj_, this->shndx_, this->address_,
 707                          this->addend_);
 708 }
 709
 710 // Copy_relocs methods.
 711
 712 // Return whether we need a COPY reloc for a relocation against GSYM.
 713 // The relocation is being applied to section SHNDX in OBJECT.
 714
 715 template<int size, bool big_endian>
 716 bool
 717 Copy_relocs<size, big_endian>::need_copy_reloc(
 718     const General_options*,
 719     Relobj* object,
 720     unsigned int shndx,
 721     Sized_symbol<size>* sym)
 722 {
 723   // FIXME: Handle -z nocopyrelocs.
 724
 725   if (sym->symsize() == 0)
 726     return false;
 727
 728   // If this is a readonly section, then we need a COPY reloc.
 729   // Otherwise we can use a dynamic reloc.
 730   if ((object->section_flags(shndx) & elfcpp::SHF_WRITE) == 0)
 731     return true;
 732
 733   return false;
 734 }
 735
 736 // Save a Rel reloc.
 737
 738 template<int size, bool big_endian>
 739 void
 740 Copy_relocs<size, big_endian>::save(
 741     Symbol* sym,
 742     Relobj* relobj,
 743     unsigned int shndx,
 744     Output_section* output_section,
 745     const elfcpp::Rel<size, big_endian>& rel)
 746 {
 747   unsigned int reloc_type = elfcpp::elf_r_type<size>(rel.get_r_info());
 748   this->entries_.push_back(Copy_reloc_entry(sym, reloc_type, relobj, shndx,
 749                                             output_section,
 750                                             rel.get_r_offset(), 0));
 751 }
 752
 753 // Save a Rela reloc.
 754
 755 template<int size, bool big_endian>
 756 void
 757 Copy_relocs<size, big_endian>::save(
 758     Symbol* sym,
 759     Relobj* relobj,
 760     unsigned int shndx,
 761     Output_section* output_section,
 762     const elfcpp::Rela<size, big_endian>& rela)
 763 {
 764   unsigned int reloc_type = elfcpp::elf_r_type<size>(rela.get_r_info());
 765   this->entries_.push_back(Copy_reloc_entry(sym, reloc_type, relobj, shndx,
 766                                             output_section,
 767                                             rela.get_r_offset(),
 768                                             rela.get_r_addend()));
 769 }
 770
 771 // Return whether there are any relocs to emit.  We don't want to emit
 772 // a reloc if the symbol is no longer defined in a dynamic object.
 773
 774 template<int size, bool big_endian>
 775 bool
 776 Copy_relocs<size, big_endian>::any_to_emit()
 777 {
 778   for (typename Copy_reloc_entries::iterator p = this->entries_.begin();
 779        p != this->entries_.end();
 780        ++p)
 781     {
 782       if (p->should_emit())
 783         return true;
 784     }
 785   return false;
 786 }
 787
 788 // Emit relocs.
 789
 790 template<int size, bool big_endian>
 791 template<int sh_type>
 792 void
 793 Copy_relocs<size, big_endian>::emit(
 794     Output_data_reloc<sh_type, true, size, big_endian>* reloc_data)
 795 {
 796   for (typename Copy_reloc_entries::iterator p = this->entries_.begin();
 797        p != this->entries_.end();
 798        ++p)
 799     {
 800       if (p->should_emit())
 801         p->emit(reloc_data);
 802     }
 803 }
 804
 805 // Track_relocs methods.
 806
 807 // Initialize the class to track the relocs.  This gets the object,
 808 // the reloc section index, and the type of the relocs.  This returns
 809 // false if something goes wrong.
 810
 811 template<int size, bool big_endian>
 812 bool
 813 Track_relocs<size, big_endian>::initialize(
 814     Object* object,
 815     unsigned int reloc_shndx,
 816     unsigned int reloc_type)
 817 {
 818   // If RELOC_SHNDX is -1U, it means there is more than one reloc
 819   // section for the .eh_frame section.  We can't handle that case.
 820   if (reloc_shndx == -1U)
 821     return false;
 822
 823   // If RELOC_SHNDX is 0, there is no reloc section.
 824   if (reloc_shndx == 0)
 825     return true;
 826
 827   // Get the contents of the reloc section.
 828   this->prelocs_ = object->section_contents(reloc_shndx, &this->len_, false);
 829
 830   if (reloc_type == elfcpp::SHT_REL)
 831     this->reloc_size_ = elfcpp::Elf_sizes<size>::rel_size;
 832   else if (reloc_type == elfcpp::SHT_RELA)
 833     this->reloc_size_ = elfcpp::Elf_sizes<size>::rela_size;
 834   else
 835     gold_unreachable();
 836
 837   if (this->len_ % this->reloc_size_ != 0)
 838     {
 839       object->error(_("reloc section size %zu is not a multiple of "
 840                       "reloc size %d\n"),
 841                     static_cast<size_t>(this->len_),
 842                     this->reloc_size_);
 843       return false;
 844     }
 845
 846   return true;
 847 }
 848
 849 // Return the offset of the next reloc, or -1 if there isn't one.
 850
 851 template<int size, bool big_endian>
 852 off_t
 853 Track_relocs<size, big_endian>::next_offset() const
 854 {
 855   if (this->pos_ >= this->len_)
 856     return -1;
 857
 858   // Rel and Rela start out the same, so we can always use Rel to find
 859   // the r_offset value.
 860   elfcpp::Rel<size, big_endian> rel(this->prelocs_ + this->pos_);
 861   return rel.get_r_offset();
 862 }
 863
 864 // Return the index of the symbol referenced by the next reloc, or -1U
 865 // if there aren't any more relocs.
 866
 867 template<int size, bool big_endian>
 868 unsigned int
 869 Track_relocs<size, big_endian>::next_symndx() const
 870 {
 871   if (this->pos_ >= this->len_)
 872     return -1U;
 873
 874   // Rel and Rela start out the same, so we can use Rel to find the
 875   // symbol index.
 876   elfcpp::Rel<size, big_endian> rel(this->prelocs_ + this->pos_);
 877   return elfcpp::elf_r_sym<size>(rel.get_r_info());
 878 }
 879
 880 // Advance to the next reloc whose r_offset is greater than or equal
 881 // to OFFSET.  Return the number of relocs we skip.
 882
 883 template<int size, bool big_endian>
 884 int
 885 Track_relocs<size, big_endian>::advance(off_t offset)
 886 {
 887   int ret = 0;
 888   while (this->pos_ < this->len_)
 889     {
 890       // Rel and Rela start out the same, so we can always use Rel to
 891       // find the r_offset value.
 892       elfcpp::Rel<size, big_endian> rel(this->prelocs_ + this->pos_);
 893       if (static_cast<off_t>(rel.get_r_offset()) >= offset)
 894         break;
 895       ++ret;
 896       this->pos_ += this->reloc_size_;
 897     }
 898   return ret;
 899 }
 900
 901 // Instantiate the templates we need.  We could use the configure
 902 // script to restrict this to only the ones for implemented targets.
 903
 904 #ifdef HAVE_TARGET_32_LITTLE
 905 template
 906 void
 907 Sized_relobj<32, false>::do_read_relocs(Read_relocs_data* rd);
 908 #endif
 909
 910 #ifdef HAVE_TARGET_32_BIG
 911 template
 912 void
 913 Sized_relobj<32, true>::do_read_relocs(Read_relocs_data* rd);
 914 #endif
 915
 916 #ifdef HAVE_TARGET_64_LITTLE
 917 template
 918 void
 919 Sized_relobj<64, false>::do_read_relocs(Read_relocs_data* rd);
 920 #endif
 921
 922 #ifdef HAVE_TARGET_64_BIG
 923 template
 924 void
 925 Sized_relobj<64, true>::do_read_relocs(Read_relocs_data* rd);
 926 #endif
 927
 928 #ifdef HAVE_TARGET_32_LITTLE
 929 template
 930 void
 931 Sized_relobj<32, false>::do_scan_relocs(const General_options& options,
 932                                         Symbol_table* symtab,
 933                                         Layout* layout,
 934                                         Read_relocs_data* rd);
 935 #endif
 936
 937 #ifdef HAVE_TARGET_32_BIG
 938 template
 939 void
 940 Sized_relobj<32, true>::do_scan_relocs(const General_options& options,
 941                                        Symbol_table* symtab,
 942                                        Layout* layout,
 943                                        Read_relocs_data* rd);
 944 #endif
 945
 946 #ifdef HAVE_TARGET_64_LITTLE
 947 template
 948 void
 949 Sized_relobj<64, false>::do_scan_relocs(const General_options& options,
 950                                         Symbol_table* symtab,
 951                                         Layout* layout,
 952                                         Read_relocs_data* rd);
 953 #endif
 954
 955 #ifdef HAVE_TARGET_64_BIG
 956 template
 957 void
 958 Sized_relobj<64, true>::do_scan_relocs(const General_options& options,
 959                                        Symbol_table* symtab,
 960                                        Layout* layout,
 961                                        Read_relocs_data* rd);
 962 #endif
 963
 964 #ifdef HAVE_TARGET_32_LITTLE
 965 template
 966 void
 967 Sized_relobj<32, false>::do_relocate(const General_options& options,
 968                                      const Symbol_table* symtab,
 969                                      const Layout* layout,
 970                                      Output_file* of);
 971 #endif
 972
 973 #ifdef HAVE_TARGET_32_BIG
 974 template
 975 void
 976 Sized_relobj<32, true>::do_relocate(const General_options& options,
 977                                     const Symbol_table* symtab,
 978                                     const Layout* layout,
 979                                     Output_file* of);
 980 #endif
 981
 982 #ifdef HAVE_TARGET_64_LITTLE
 983 template
 984 void
 985 Sized_relobj<64, false>::do_relocate(const General_options& options,
 986                                      const Symbol_table* symtab,
 987                                      const Layout* layout,
 988                                      Output_file* of);
 989 #endif
 990
 991 #ifdef HAVE_TARGET_64_BIG
 992 template
 993 void
 994 Sized_relobj<64, true>::do_relocate(const General_options& options,
 995                                     const Symbol_table* symtab,
 996                                     const Layout* layout,
 997                                     Output_file* of);
 998 #endif
 999
1000 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
1001 template
1002 class Merged_symbol_value<32>;
1003 #endif
1004
1005 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
1006 template
1007 class Merged_symbol_value<64>;
1008 #endif
1009
1010 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
1011 template
1012 class Symbol_value<32>;
1013 #endif
1014
1015 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
1016 template
1017 class Symbol_value<64>;
1018 #endif
1019
1020 #ifdef HAVE_TARGET_32_LITTLE
1021 template
1022 class Copy_relocs<32, false>;
1023 #endif
1024
1025 #ifdef HAVE_TARGET_32_BIG
1026 template
1027 class Copy_relocs<32, true>;
1028 #endif
1029
1030 #ifdef HAVE_TARGET_64_LITTLE
1031 template
1032 class Copy_relocs<64, false>;
1033 #endif
1034
1035 #ifdef HAVE_TARGET_64_BIG
1036 template
1037 class Copy_relocs<64, true>;
1038 #endif
1039
1040 #ifdef HAVE_TARGET_32_LITTLE
1041 template
1042 void
1043 Copy_relocs<32, false>::emit<elfcpp::SHT_REL>(
1044     Output_data_reloc<elfcpp::SHT_REL, true, 32, false>*);
1045 #endif
1046
1047 #ifdef HAVE_TARGET_32_BIG
1048 template
1049 void
1050 Copy_relocs<32, true>::emit<elfcpp::SHT_REL>(
1051     Output_data_reloc<elfcpp::SHT_REL, true, 32, true>*);
1052 #endif
1053
1054 #ifdef HAVE_TARGET_64_LITTLE
1055 template
1056 void
1057 Copy_relocs<64, false>::emit<elfcpp::SHT_REL>(
1058     Output_data_reloc<elfcpp::SHT_REL, true, 64, false>*);
1059 #endif
1060
1061 #ifdef HAVE_TARGET_64_BIG
1062 template
1063 void
1064 Copy_relocs<64, true>::emit<elfcpp::SHT_REL>(
1065     Output_data_reloc<elfcpp::SHT_REL, true, 64, true>*);
1066 #endif
1067
1068 #ifdef HAVE_TARGET_32_LITTLE
1069 template
1070 void
1071 Copy_relocs<32, false>::emit<elfcpp::SHT_RELA>(
1072     Output_data_reloc<elfcpp::SHT_RELA , true, 32, false>*);
1073 #endif
1074
1075 #ifdef HAVE_TARGET_32_BIG
1076 template
1077 void
1078 Copy_relocs<32, true>::emit<elfcpp::SHT_RELA>(
1079     Output_data_reloc<elfcpp::SHT_RELA, true, 32, true>*);
1080 #endif
1081
1082 #ifdef HAVE_TARGET_64_LITTLE
1083 template
1084 void
1085 Copy_relocs<64, false>::emit<elfcpp::SHT_RELA>(
1086     Output_data_reloc<elfcpp::SHT_RELA, true, 64, false>*);
1087 #endif
1088
1089 #ifdef HAVE_TARGET_64_BIG
1090 template
1091 void
1092 Copy_relocs<64, true>::emit<elfcpp::SHT_RELA>(
1093     Output_data_reloc<elfcpp::SHT_RELA, true, 64, true>*);
1094 #endif
1095
1096 #ifdef HAVE_TARGET_32_LITTLE
1097 template
1098 class Track_relocs<32, false>;
1099 #endif
1100
1101 #ifdef HAVE_TARGET_32_BIG
1102 template
1103 class Track_relocs<32, true>;
1104 #endif
1105
1106 #ifdef HAVE_TARGET_64_LITTLE
1107 template
1108 class Track_relocs<64, false>;
1109 #endif
1110
1111 #ifdef HAVE_TARGET_64_BIG
1112 template
1113 class Track_relocs<64, true>;
1114 #endif
1115
1116 } // End namespace gold.