gold/reloc.cc

   1 // reloc.cc -- relocate input files for gold.
   2
   3 // Copyright 2006, 2007, 2008, 2009 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 <algorithm>
  26
  27 #include "workqueue.h"
  28 #include "symtab.h"
  29 #include "output.h"
  30 #include "merge.h"
  31 #include "object.h"
  32 #include "target-reloc.h"
  33 #include "reloc.h"
  34 #include "icf.h"
  35
  36 namespace gold
  37 {
  38
  39 // Read_relocs methods.
  40
  41 // These tasks just read the relocation information from the file.
  42 // After reading it, the start another task to process the
  43 // information.  These tasks requires access to the file.
  44
  45 Task_token*
  46 Read_relocs::is_runnable()
  47 {
  48   return this->object_->is_locked() ? this->object_->token() : NULL;
  49 }
  50
  51 // Lock the file.
  52
  53 void
  54 Read_relocs::locks(Task_locker* tl)
  55 {
  56   tl->add(this, this->object_->token());
  57 }
  58
  59 // Read the relocations and then start a Scan_relocs_task.
  60
  61 void
  62 Read_relocs::run(Workqueue* workqueue)
  63 {
  64   Read_relocs_data *rd = new Read_relocs_data;
  65   this->object_->read_relocs(rd);
  66   this->object_->set_relocs_data(rd);
  67   this->object_->release();
  68
  69   // If garbage collection or identical comdat folding is desired, we
  70   // process the relocs first before scanning them.  Scanning of relocs is
  71   // done only after garbage or identical sections is identified.
  72   if (parameters->options().gc_sections()
  73       || parameters->options().icf_enabled())
  74     {
  75       workqueue->queue_next(new Gc_process_relocs(this->options_,
  76                                                   this->symtab_,
  77                                                   this->layout_,
  78                                                   this->object_, rd,
  79                                                   this->symtab_lock_,
  80                                                   this->blocker_));
  81     }
  82   else
  83     {
  84       workqueue->queue_next(new Scan_relocs(this->options_, this->symtab_,
  85                                             this->layout_, this->object_, rd,
  86                                             this->symtab_lock_,
  87                                             this->blocker_));
  88     }
  89 }
  90
  91 // Return a debugging name for the task.
  92
  93 std::string
  94 Read_relocs::get_name() const
  95 {
  96   return "Read_relocs " + this->object_->name();
  97 }
  98
  99 // Gc_process_relocs methods.
 100
 101 // These tasks process the relocations read by Read_relocs and
 102 // determine which sections are referenced and which are garbage.
 103 // This task is done only when --gc-sections is used.
 104
 105 Task_token*
 106 Gc_process_relocs::is_runnable()
 107 {
 108   if (this->object_->is_locked())
 109     return this->object_->token();
 110   return NULL;
 111 }
 112
 113 void
 114 Gc_process_relocs::locks(Task_locker* tl)
 115 {
 116   tl->add(this, this->object_->token());
 117   tl->add(this, this->blocker_);
 118 }
 119
 120 void
 121 Gc_process_relocs::run(Workqueue*)
 122 {
 123   this->object_->gc_process_relocs(this->options_, this->symtab_, this->layout_,
 124                      this->rd_);
 125   this->object_->release();
 126 }
 127
 128 // Return a debugging name for the task.
 129
 130 std::string
 131 Gc_process_relocs::get_name() const
 132 {
 133   return "Gc_process_relocs " + this->object_->name();
 134 }
 135
 136 // Scan_relocs methods.
 137
 138 // These tasks scan the relocations read by Read_relocs and mark up
 139 // the symbol table to indicate which relocations are required.  We
 140 // use a lock on the symbol table to keep them from interfering with
 141 // each other.
 142
 143 Task_token*
 144 Scan_relocs::is_runnable()
 145 {
 146   if (!this->symtab_lock_->is_writable())
 147     return this->symtab_lock_;
 148   if (this->object_->is_locked())
 149     return this->object_->token();
 150   return NULL;
 151 }
 152
 153 // Return the locks we hold: one on the file, one on the symbol table
 154 // and one blocker.
 155
 156 void
 157 Scan_relocs::locks(Task_locker* tl)
 158 {
 159   tl->add(this, this->object_->token());
 160   tl->add(this, this->symtab_lock_);
 161   tl->add(this, this->blocker_);
 162 }
 163
 164 // Scan the relocs.
 165
 166 void
 167 Scan_relocs::run(Workqueue*)
 168 {
 169   this->object_->scan_relocs(this->options_, this->symtab_, this->layout_,
 170                              this->rd_);
 171   this->object_->release();
 172   delete this->rd_;
 173   this->rd_ = NULL;
 174 }
 175
 176 // Return a debugging name for the task.
 177
 178 std::string
 179 Scan_relocs::get_name() const
 180 {
 181   return "Scan_relocs " + this->object_->name();
 182 }
 183
 184 // Relocate_task methods.
 185
 186 // We may have to wait for the output sections to be written.
 187
 188 Task_token*
 189 Relocate_task::is_runnable()
 190 {
 191   if (this->object_->relocs_must_follow_section_writes()
 192       && this->output_sections_blocker_->is_blocked())
 193     return this->output_sections_blocker_;
 194
 195   if (this->object_->is_locked())
 196     return this->object_->token();
 197
 198   return NULL;
 199 }
 200
 201 // We want to lock the file while we run.  We want to unblock
 202 // INPUT_SECTIONS_BLOCKER and FINAL_BLOCKER when we are done.
 203 // INPUT_SECTIONS_BLOCKER may be NULL.
 204
 205 void
 206 Relocate_task::locks(Task_locker* tl)
 207 {
 208   if (this->input_sections_blocker_ != NULL)
 209     tl->add(this, this->input_sections_blocker_);
 210   tl->add(this, this->final_blocker_);
 211   tl->add(this, this->object_->token());
 212 }
 213
 214 // Run the task.
 215
 216 void
 217 Relocate_task::run(Workqueue*)
 218 {
 219   this->object_->relocate(this->options_, this->symtab_, this->layout_,
 220                           this->of_);
 221
 222   // This is normally the last thing we will do with an object, so
 223   // uncache all views.
 224   this->object_->clear_view_cache_marks();
 225
 226   this->object_->release();
 227 }
 228
 229 // Return a debugging name for the task.
 230
 231 std::string
 232 Relocate_task::get_name() const
 233 {
 234   return "Relocate_task " + this->object_->name();
 235 }
 236
 237 // Read the relocs and local symbols from the object file and store
 238 // the information in RD.
 239
 240 template<int size, bool big_endian>
 241 void
 242 Sized_relobj<size, big_endian>::do_read_relocs(Read_relocs_data* rd)
 243 {
 244   rd->relocs.clear();
 245
 246   unsigned int shnum = this->shnum();
 247   if (shnum == 0)
 248     return;
 249
 250   rd->relocs.reserve(shnum / 2);
 251
 252   const Output_sections& out_sections(this->output_sections());
 253   const std::vector<Address>& out_offsets(this->section_offsets_);
 254
 255   const unsigned char *pshdrs = this->get_view(this->elf_file_.shoff(),
 256                                                shnum * This::shdr_size,
 257                                                true, true);
 258   // Skip the first, dummy, section.
 259   const unsigned char *ps = pshdrs + This::shdr_size;
 260   for (unsigned int i = 1; i < shnum; ++i, ps += This::shdr_size)
 261     {
 262       typename This::Shdr shdr(ps);
 263
 264       unsigned int sh_type = shdr.get_sh_type();
 265       if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
 266         continue;
 267
 268       unsigned int shndx = this->adjust_shndx(shdr.get_sh_info());
 269       if (shndx >= shnum)
 270         {
 271           this->error(_("relocation section %u has bad info %u"),
 272                       i, shndx);
 273           continue;
 274         }
 275
 276       Output_section* os = out_sections[shndx];
 277       if (os == NULL)
 278         continue;
 279
 280       // We are scanning relocations in order to fill out the GOT and
 281       // PLT sections.  Relocations for sections which are not
 282       // allocated (typically debugging sections) should not add new
 283       // GOT and PLT entries.  So we skip them unless this is a
 284       // relocatable link or we need to emit relocations.  FIXME: What
 285       // should we do if a linker script maps a section with SHF_ALLOC
 286       // clear to a section with SHF_ALLOC set?
 287       typename This::Shdr secshdr(pshdrs + shndx * This::shdr_size);
 288       bool is_section_allocated = ((secshdr.get_sh_flags() & elfcpp::SHF_ALLOC)
 289                                    != 0);
 290       if (!is_section_allocated
 291           && !parameters->options().relocatable()
 292           && !parameters->options().emit_relocs())
 293         continue;
 294
 295       if (this->adjust_shndx(shdr.get_sh_link()) != this->symtab_shndx_)
 296         {
 297           this->error(_("relocation section %u uses unexpected "
 298                         "symbol table %u"),
 299                       i, this->adjust_shndx(shdr.get_sh_link()));
 300           continue;
 301         }
 302
 303       off_t sh_size = shdr.get_sh_size();
 304
 305       unsigned int reloc_size;
 306       if (sh_type == elfcpp::SHT_REL)
 307         reloc_size = elfcpp::Elf_sizes<size>::rel_size;
 308       else
 309         reloc_size = elfcpp::Elf_sizes<size>::rela_size;
 310       if (reloc_size != shdr.get_sh_entsize())
 311         {
 312           this->error(_("unexpected entsize for reloc section %u: %lu != %u"),
 313                       i, static_cast<unsigned long>(shdr.get_sh_entsize()),
 314                       reloc_size);
 315           continue;
 316         }
 317
 318       size_t reloc_count = sh_size / reloc_size;
 319       if (static_cast<off_t>(reloc_count * reloc_size) != sh_size)
 320         {
 321           this->error(_("reloc section %u size %lu uneven"),
 322                       i, static_cast<unsigned long>(sh_size));
 323           continue;
 324         }
 325
 326       rd->relocs.push_back(Section_relocs());
 327       Section_relocs& sr(rd->relocs.back());
 328       sr.reloc_shndx = i;
 329       sr.data_shndx = shndx;
 330       sr.contents = this->get_lasting_view(shdr.get_sh_offset(), sh_size,
 331                                            true, true);
 332       sr.sh_type = sh_type;
 333       sr.reloc_count = reloc_count;
 334       sr.output_section = os;
 335       sr.needs_special_offset_handling = out_offsets[shndx] == invalid_address;
 336       sr.is_data_section_allocated = is_section_allocated;
 337     }
 338
 339   // Read the local symbols.
 340   gold_assert(this->symtab_shndx_ != -1U);
 341   if (this->symtab_shndx_ == 0 || this->local_symbol_count_ == 0)
 342     rd->local_symbols = NULL;
 343   else
 344     {
 345       typename This::Shdr symtabshdr(pshdrs
 346                                      + this->symtab_shndx_ * This::shdr_size);
 347       gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
 348       const int sym_size = This::sym_size;
 349       const unsigned int loccount = this->local_symbol_count_;
 350       gold_assert(loccount == symtabshdr.get_sh_info());
 351       off_t locsize = loccount * sym_size;
 352       rd->local_symbols = this->get_lasting_view(symtabshdr.get_sh_offset(),
 353                                                  locsize, true, true);
 354     }
 355 }
 356
 357 // Process the relocs to generate mappings from source sections to referenced
 358 // sections.  This is used during garbage colletion to determine garbage
 359 // sections.
 360
 361 template<int size, bool big_endian>
 362 void
 363 Sized_relobj<size, big_endian>::do_gc_process_relocs(const General_options& options,
 364                                                Symbol_table* symtab,
 365                                                Layout* layout,
 366                                                Read_relocs_data* rd)
 367 {
 368   Sized_target<size, big_endian>* target =
 369     parameters->sized_target<size, big_endian>();
 370
 371   const unsigned char* local_symbols;
 372   if (rd->local_symbols == NULL)
 373     local_symbols = NULL;
 374   else
 375     local_symbols = rd->local_symbols->data();
 376
 377   for (Read_relocs_data::Relocs_list::iterator p = rd->relocs.begin();
 378        p != rd->relocs.end();
 379        ++p)
 380     {
 381       if (!parameters->options().relocatable())
 382           {
 383             // As noted above, when not generating an object file, we
 384             // only scan allocated sections.  We may see a non-allocated
 385             // section here if we are emitting relocs.
 386             if (p->is_data_section_allocated)
 387               target->gc_process_relocs(options, symtab, layout, this,
 388                                         p->data_shndx, p->sh_type,
 389                                         p->contents->data(), p->reloc_count,
 390                                         p->output_section,
 391                                         p->needs_special_offset_handling,
 392                                         this->local_symbol_count_,
 393                                         local_symbols);
 394         }
 395     }
 396 }
 397
 398
 399 // Scan the relocs and adjust the symbol table.  This looks for
 400 // relocations which require GOT/PLT/COPY relocations.
 401
 402 template<int size, bool big_endian>
 403 void
 404 Sized_relobj<size, big_endian>::do_scan_relocs(const General_options& options,
 405                                                Symbol_table* symtab,
 406                                                Layout* layout,
 407                                                Read_relocs_data* rd)
 408 {
 409   Sized_target<size, big_endian>* target =
 410     parameters->sized_target<size, big_endian>();
 411
 412   const unsigned char* local_symbols;
 413   if (rd->local_symbols == NULL)
 414     local_symbols = NULL;
 415   else
 416     local_symbols = rd->local_symbols->data();
 417
 418   for (Read_relocs_data::Relocs_list::iterator p = rd->relocs.begin();
 419        p != rd->relocs.end();
 420        ++p)
 421     {
 422       // When garbage collection is on, unreferenced sections are not included
 423       // in the link that would have been included normally. This is known only
 424       // after Read_relocs hence this check has to be done again.
 425       if (parameters->options().gc_sections()
 426           || parameters->options().icf_enabled())
 427         {
 428           if (p->output_section == NULL)
 429             continue;
 430         }
 431       if (!parameters->options().relocatable())
 432         {
 433           // As noted above, when not generating an object file, we
 434           // only scan allocated sections.  We may see a non-allocated
 435           // section here if we are emitting relocs.
 436           if (p->is_data_section_allocated)
 437             target->scan_relocs(options, symtab, layout, this, p->data_shndx,
 438                                 p->sh_type, p->contents->data(),
 439                                 p->reloc_count, p->output_section,
 440                                 p->needs_special_offset_handling,
 441                                 this->local_symbol_count_,
 442                                 local_symbols);
 443           if (parameters->options().emit_relocs())
 444             this->emit_relocs_scan(options, symtab, layout, local_symbols, p);
 445         }
 446       else
 447         {
 448           Relocatable_relocs* rr = this->relocatable_relocs(p->reloc_shndx);
 449           gold_assert(rr != NULL);
 450           rr->set_reloc_count(p->reloc_count);
 451           target->scan_relocatable_relocs(options, symtab, layout, this,
 452                                           p->data_shndx, p->sh_type,
 453                                           p->contents->data(),
 454                                           p->reloc_count,
 455                                           p->output_section,
 456                                           p->needs_special_offset_handling,
 457                                           this->local_symbol_count_,
 458                                           local_symbols,
 459                                           rr);
 460         }
 461
 462       delete p->contents;
 463       p->contents = NULL;
 464     }
 465
 466   if (rd->local_symbols != NULL)
 467     {
 468       delete rd->local_symbols;
 469       rd->local_symbols = NULL;
 470     }
 471 }
 472
 473 // This is a strategy class we use when scanning for --emit-relocs.
 474
 475 template<int sh_type>
 476 class Emit_relocs_strategy
 477 {
 478  public:
 479   // A local non-section symbol.
 480   inline Relocatable_relocs::Reloc_strategy
 481   local_non_section_strategy(unsigned int, Relobj*, unsigned int)
 482   { return Relocatable_relocs::RELOC_COPY; }
 483
 484   // A local section symbol.
 485   inline Relocatable_relocs::Reloc_strategy
 486   local_section_strategy(unsigned int, Relobj*)
 487   {
 488     if (sh_type == elfcpp::SHT_RELA)
 489       return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA;
 490     else
 491       {
 492         // The addend is stored in the section contents.  Since this
 493         // is not a relocatable link, we are going to apply the
 494         // relocation contents to the section as usual.  This means
 495         // that we have no way to record the original addend.  If the
 496         // original addend is not zero, there is basically no way for
 497         // the user to handle this correctly.  Caveat emptor.
 498         return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0;
 499       }
 500   }
 501
 502   // A global symbol.
 503   inline Relocatable_relocs::Reloc_strategy
 504   global_strategy(unsigned int, Relobj*, unsigned int)
 505   { return Relocatable_relocs::RELOC_COPY; }
 506 };
 507
 508 // Scan the input relocations for --emit-relocs.
 509
 510 template<int size, bool big_endian>
 511 void
 512 Sized_relobj<size, big_endian>::emit_relocs_scan(
 513     const General_options& options,
 514     Symbol_table* symtab,
 515     Layout* layout,
 516     const unsigned char* plocal_syms,
 517     const Read_relocs_data::Relocs_list::iterator& p)
 518 {
 519   Relocatable_relocs* rr = this->relocatable_relocs(p->reloc_shndx);
 520   gold_assert(rr != NULL);
 521   rr->set_reloc_count(p->reloc_count);
 522
 523   if (p->sh_type == elfcpp::SHT_REL)
 524     this->emit_relocs_scan_reltype<elfcpp::SHT_REL>(options, symtab, layout,
 525                                                     plocal_syms, p, rr);
 526   else
 527     {
 528       gold_assert(p->sh_type == elfcpp::SHT_RELA);
 529       this->emit_relocs_scan_reltype<elfcpp::SHT_RELA>(options, symtab,
 530                                                        layout, plocal_syms, p,
 531                                                        rr);
 532     }
 533 }
 534
 535 // Scan the input relocation for --emit-relocs, templatized on the
 536 // type of the relocation section.
 537
 538 template<int size, bool big_endian>
 539 template<int sh_type>
 540 void
 541 Sized_relobj<size, big_endian>::emit_relocs_scan_reltype(
 542     const General_options& options,
 543     Symbol_table* symtab,
 544     Layout* layout,
 545     const unsigned char* plocal_syms,
 546     const Read_relocs_data::Relocs_list::iterator& p,
 547     Relocatable_relocs* rr)
 548 {
 549   scan_relocatable_relocs<size, big_endian, sh_type,
 550                           Emit_relocs_strategy<sh_type> >(
 551     options,
 552     symtab,
 553     layout,
 554     this,
 555     p->data_shndx,
 556     p->contents->data(),
 557     p->reloc_count,
 558     p->output_section,
 559     p->needs_special_offset_handling,
 560     this->local_symbol_count_,
 561     plocal_syms,
 562     rr);
 563 }
 564
 565 // Relocate the input sections and write out the local symbols.
 566
 567 template<int size, bool big_endian>
 568 void
 569 Sized_relobj<size, big_endian>::do_relocate(const General_options& options,
 570                                             const Symbol_table* symtab,
 571                                             const Layout* layout,
 572                                             Output_file* of)
 573 {
 574   unsigned int shnum = this->shnum();
 575
 576   // Read the section headers.
 577   const unsigned char* pshdrs = this->get_view(this->elf_file_.shoff(),
 578                                                shnum * This::shdr_size,
 579                                                true, true);
 580
 581   Views views;
 582   views.resize(shnum);
 583
 584   // Make two passes over the sections.  The first one copies the
 585   // section data to the output file.  The second one applies
 586   // relocations.
 587
 588   this->write_sections(pshdrs, of, &views);
 589
 590   // To speed up relocations, we set up hash tables for fast lookup of
 591   // input offsets to output addresses.
 592   this->initialize_input_to_output_maps();
 593
 594   // Apply relocations.
 595
 596   this->relocate_sections(options, symtab, layout, pshdrs, &views);
 597
 598   // After we've done the relocations, we release the hash tables,
 599   // since we no longer need them.
 600   this->free_input_to_output_maps();
 601
 602   // Write out the accumulated views.
 603   for (unsigned int i = 1; i < shnum; ++i)
 604     {
 605       if (views[i].view != NULL)
 606         {
 607           if (!views[i].is_postprocessing_view)
 608             {
 609               if (views[i].is_input_output_view)
 610                 of->write_input_output_view(views[i].offset,
 611                                             views[i].view_size,
 612                                             views[i].view);
 613               else
 614                 of->write_output_view(views[i].offset, views[i].view_size,
 615                                       views[i].view);
 616             }
 617         }
 618     }
 619
 620   // Write out the local symbols.
 621   this->write_local_symbols(of, layout->sympool(), layout->dynpool(),
 622                             layout->symtab_xindex(), layout->dynsym_xindex());
 623
 624   // We should no longer need the local symbol values.
 625   this->clear_local_symbols();
 626 }
 627
 628 // Sort a Read_multiple vector by file offset.
 629 struct Read_multiple_compare
 630 {
 631   inline bool
 632   operator()(const File_read::Read_multiple_entry& rme1,
 633              const File_read::Read_multiple_entry& rme2) const
 634   { return rme1.file_offset < rme2.file_offset; }
 635 };
 636
 637 // Write section data to the output file.  PSHDRS points to the
 638 // section headers.  Record the views in *PVIEWS for use when
 639 // relocating.
 640
 641 template<int size, bool big_endian>
 642 void
 643 Sized_relobj<size, big_endian>::write_sections(const unsigned char* pshdrs,
 644                                                Output_file* of,
 645                                                Views* pviews)
 646 {
 647   unsigned int shnum = this->shnum();
 648   const Output_sections& out_sections(this->output_sections());
 649   const std::vector<Address>& out_offsets(this->section_offsets_);
 650
 651   File_read::Read_multiple rm;
 652   bool is_sorted = true;
 653
 654   const unsigned char* p = pshdrs + This::shdr_size;
 655   for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
 656     {
 657       View_size* pvs = &(*pviews)[i];
 658
 659       pvs->view = NULL;
 660
 661       const Output_section* os = out_sections[i];
 662       if (os == NULL)
 663         continue;
 664       Address output_offset = out_offsets[i];
 665
 666       typename This::Shdr shdr(p);
 667
 668       if (shdr.get_sh_type() == elfcpp::SHT_NOBITS)
 669         continue;
 670
 671       if ((parameters->options().relocatable()
 672            || parameters->options().emit_relocs())
 673           && (shdr.get_sh_type() == elfcpp::SHT_REL
 674               || shdr.get_sh_type() == elfcpp::SHT_RELA)
 675           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
 676         {
 677           // This is a reloc section in a relocatable link or when
 678           // emitting relocs.  We don't need to read the input file.
 679           // The size and file offset are stored in the
 680           // Relocatable_relocs structure.
 681           Relocatable_relocs* rr = this->relocatable_relocs(i);
 682           gold_assert(rr != NULL);
 683           Output_data* posd = rr->output_data();
 684           gold_assert(posd != NULL);
 685
 686           pvs->offset = posd->offset();
 687           pvs->view_size = posd->data_size();
 688           pvs->view = of->get_output_view(pvs->offset, pvs->view_size);
 689           pvs->address = posd->address();
 690           pvs->is_input_output_view = false;
 691           pvs->is_postprocessing_view = false;
 692
 693           continue;
 694         }
 695
 696       // In the normal case, this input section is simply mapped to
 697       // the output section at offset OUTPUT_OFFSET.
 698
 699       // However, if OUTPUT_OFFSET == INVALID_ADDRESS, then input data is
 700       // handled specially--e.g., a .eh_frame section.  The relocation
 701       // routines need to check for each reloc where it should be
 702       // applied.  For this case, we need an input/output view for the
 703       // entire contents of the section in the output file.  We don't
 704       // want to copy the contents of the input section to the output
 705       // section; the output section contents were already written,
 706       // and we waited for them in Relocate_task::is_runnable because
 707       // relocs_must_follow_section_writes is set for the object.
 708
 709       // Regardless of which of the above cases is true, we have to
 710       // check requires_postprocessing of the output section.  If that
 711       // is false, then we work with views of the output file
 712       // directly.  If it is true, then we work with a separate
 713       // buffer, and the output section is responsible for writing the
 714       // final data to the output file.
 715
 716       off_t output_section_offset;
 717       Address output_section_size;
 718       if (!os->requires_postprocessing())
 719         {
 720           output_section_offset = os->offset();
 721           output_section_size = convert_types<Address, off_t>(os->data_size());
 722         }
 723       else
 724         {
 725           output_section_offset = 0;
 726           output_section_size =
 727               convert_types<Address, off_t>(os->postprocessing_buffer_size());
 728         }
 729
 730       off_t view_start;
 731       section_size_type view_size;
 732       if (output_offset != invalid_address)
 733         {
 734           view_start = output_section_offset + output_offset;
 735           view_size = convert_to_section_size_type(shdr.get_sh_size());
 736         }
 737       else
 738         {
 739           view_start = output_section_offset;
 740           view_size = convert_to_section_size_type(output_section_size);
 741         }
 742
 743       if (view_size == 0)
 744         continue;
 745
 746       gold_assert(output_offset == invalid_address
 747                   || output_offset + view_size <= output_section_size);
 748
 749       unsigned char* view;
 750       if (os->requires_postprocessing())
 751         {
 752           unsigned char* buffer = os->postprocessing_buffer();
 753           view = buffer + view_start;
 754           if (output_offset != invalid_address)
 755             {
 756               off_t sh_offset = shdr.get_sh_offset();
 757               if (!rm.empty() && rm.back().file_offset > sh_offset)
 758                 is_sorted = false;
 759               rm.push_back(File_read::Read_multiple_entry(sh_offset,
 760                                                           view_size, view));
 761             }
 762         }
 763       else
 764         {
 765           if (output_offset == invalid_address)
 766             view = of->get_input_output_view(view_start, view_size);
 767           else
 768             {
 769               view = of->get_output_view(view_start, view_size);
 770               off_t sh_offset = shdr.get_sh_offset();
 771               if (!rm.empty() && rm.back().file_offset > sh_offset)
 772                 is_sorted = false;
 773               rm.push_back(File_read::Read_multiple_entry(sh_offset,
 774                                                           view_size, view));
 775             }
 776         }
 777
 778       pvs->view = view;
 779       pvs->address = os->address();
 780       if (output_offset != invalid_address)
 781         pvs->address += output_offset;
 782       pvs->offset = view_start;
 783       pvs->view_size = view_size;
 784       pvs->is_input_output_view = output_offset == invalid_address;
 785       pvs->is_postprocessing_view = os->requires_postprocessing();
 786     }
 787
 788   // Actually read the data.
 789   if (!rm.empty())
 790     {
 791       if (!is_sorted)
 792         std::sort(rm.begin(), rm.end(), Read_multiple_compare());
 793       this->read_multiple(rm);
 794     }
 795 }
 796
 797 // Relocate section data.  VIEWS points to the section data as views
 798 // in the output file.
 799
 800 template<int size, bool big_endian>
 801 void
 802 Sized_relobj<size, big_endian>::relocate_sections(
 803     const General_options& options,
 804     const Symbol_table* symtab,
 805     const Layout* layout,
 806     const unsigned char* pshdrs,
 807     Views* pviews)
 808 {
 809   unsigned int shnum = this->shnum();
 810   Sized_target<size, big_endian>* target =
 811     parameters->sized_target<size, big_endian>();
 812
 813   const Output_sections& out_sections(this->output_sections());
 814   const std::vector<Address>& out_offsets(this->section_offsets_);
 815
 816   Relocate_info<size, big_endian> relinfo;
 817   relinfo.options = &options;
 818   relinfo.symtab = symtab;
 819   relinfo.layout = layout;
 820   relinfo.object = this;
 821
 822   const unsigned char* p = pshdrs + This::shdr_size;
 823   for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
 824     {
 825       typename This::Shdr shdr(p);
 826
 827       unsigned int sh_type = shdr.get_sh_type();
 828       if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
 829         continue;
 830
 831       off_t sh_size = shdr.get_sh_size();
 832       if (sh_size == 0)
 833         continue;
 834
 835       unsigned int index = this->adjust_shndx(shdr.get_sh_info());
 836       if (index >= this->shnum())
 837         {
 838           this->error(_("relocation section %u has bad info %u"),
 839                       i, index);
 840           continue;
 841         }
 842
 843       Output_section* os = out_sections[index];
 844       if (os == NULL)
 845         {
 846           // This relocation section is against a section which we
 847           // discarded.
 848           continue;
 849         }
 850       Address output_offset = out_offsets[index];
 851
 852       gold_assert((*pviews)[index].view != NULL);
 853       if (parameters->options().relocatable())
 854         gold_assert((*pviews)[i].view != NULL);
 855
 856       if (this->adjust_shndx(shdr.get_sh_link()) != this->symtab_shndx_)
 857         {
 858           gold_error(_("relocation section %u uses unexpected "
 859                        "symbol table %u"),
 860                      i, this->adjust_shndx(shdr.get_sh_link()));
 861           continue;
 862         }
 863
 864       const unsigned char* prelocs = this->get_view(shdr.get_sh_offset(),
 865                                                     sh_size, true, false);
 866
 867       unsigned int reloc_size;
 868       if (sh_type == elfcpp::SHT_REL)
 869         reloc_size = elfcpp::Elf_sizes<size>::rel_size;
 870       else
 871         reloc_size = elfcpp::Elf_sizes<size>::rela_size;
 872
 873       if (reloc_size != shdr.get_sh_entsize())
 874         {
 875           gold_error(_("unexpected entsize for reloc section %u: %lu != %u"),
 876                      i, static_cast<unsigned long>(shdr.get_sh_entsize()),
 877                      reloc_size);
 878           continue;
 879         }
 880
 881       size_t reloc_count = sh_size / reloc_size;
 882       if (static_cast<off_t>(reloc_count * reloc_size) != sh_size)
 883         {
 884           gold_error(_("reloc section %u size %lu uneven"),
 885                      i, static_cast<unsigned long>(sh_size));
 886           continue;
 887         }
 888
 889       gold_assert(output_offset != invalid_address
 890                   || this->relocs_must_follow_section_writes());
 891
 892       relinfo.reloc_shndx = i;
 893       relinfo.data_shndx = index;
 894       unsigned char* view = (*pviews)[index].view;
 895       Address address = (*pviews)[index].address;
 896       section_size_type view_size = (*pviews)[index].view_size;
 897
 898       Reloc_symbol_changes* reloc_map = NULL;
 899       if (this->uses_split_stack() && output_offset != invalid_address)
 900         {
 901           typename This::Shdr data_shdr(pshdrs + index * This::shdr_size);
 902           if ((data_shdr.get_sh_flags() & elfcpp::SHF_EXECINSTR) != 0)
 903             this->split_stack_adjust(symtab, pshdrs, sh_type, index,
 904                                      prelocs, reloc_count, view, view_size,
 905                                      &reloc_map);
 906         }
 907
 908       if (!parameters->options().relocatable())
 909         {
 910           target->relocate_section(&relinfo, sh_type, prelocs, reloc_count, os,
 911                                    output_offset == invalid_address,
 912                                    view, address, view_size, reloc_map);
 913           if (parameters->options().emit_relocs())
 914             this->emit_relocs(&relinfo, i, sh_type, prelocs, reloc_count,
 915                               os, output_offset, view, address, view_size,
 916                               (*pviews)[i].view, (*pviews)[i].view_size);
 917         }
 918       else
 919         {
 920           Relocatable_relocs* rr = this->relocatable_relocs(i);
 921           target->relocate_for_relocatable(&relinfo, sh_type, prelocs,
 922                                            reloc_count, os, output_offset, rr,
 923                                            view, address, view_size,
 924                                            (*pviews)[i].view,
 925                                            (*pviews)[i].view_size);
 926         }
 927     }
 928 }
 929
 930 // Emit the relocs for --emit-relocs.
 931
 932 template<int size, bool big_endian>
 933 void
 934 Sized_relobj<size, big_endian>::emit_relocs(
 935     const Relocate_info<size, big_endian>* relinfo,
 936     unsigned int i,
 937     unsigned int sh_type,
 938     const unsigned char* prelocs,
 939     size_t reloc_count,
 940     Output_section* output_section,
 941     typename elfcpp::Elf_types<size>::Elf_Addr offset_in_output_section,
 942     unsigned char* view,
 943     typename elfcpp::Elf_types<size>::Elf_Addr address,
 944     section_size_type view_size,
 945     unsigned char* reloc_view,
 946     section_size_type reloc_view_size)
 947 {
 948   if (sh_type == elfcpp::SHT_REL)
 949     this->emit_relocs_reltype<elfcpp::SHT_REL>(relinfo, i, prelocs,
 950                                                reloc_count, output_section,
 951                                                offset_in_output_section,
 952                                                view, address, view_size,
 953                                                reloc_view, reloc_view_size);
 954   else
 955     {
 956       gold_assert(sh_type == elfcpp::SHT_RELA);
 957       this->emit_relocs_reltype<elfcpp::SHT_RELA>(relinfo, i, prelocs,
 958                                                   reloc_count, output_section,
 959                                                   offset_in_output_section,
 960                                                   view, address, view_size,
 961                                                   reloc_view, reloc_view_size);
 962     }
 963 }
 964
 965 // Emit the relocs for --emit-relocs, templatized on the type of the
 966 // relocation section.
 967
 968 template<int size, bool big_endian>
 969 template<int sh_type>
 970 void
 971 Sized_relobj<size, big_endian>::emit_relocs_reltype(
 972     const Relocate_info<size, big_endian>* relinfo,
 973     unsigned int i,
 974     const unsigned char* prelocs,
 975     size_t reloc_count,
 976     Output_section* output_section,
 977     typename elfcpp::Elf_types<size>::Elf_Addr offset_in_output_section,
 978     unsigned char* view,
 979     typename elfcpp::Elf_types<size>::Elf_Addr address,
 980     section_size_type view_size,
 981     unsigned char* reloc_view,
 982     section_size_type reloc_view_size)
 983 {
 984   const Relocatable_relocs* rr = this->relocatable_relocs(i);
 985   relocate_for_relocatable<size, big_endian, sh_type>(
 986     relinfo,
 987     prelocs,
 988     reloc_count,
 989     output_section,
 990     offset_in_output_section,
 991     rr,
 992     view,
 993     address,
 994     view_size,
 995     reloc_view,
 996     reloc_view_size);
 997 }
 998
 999 // Create merge hash tables for the local symbols.  These are used to
1000 // speed up relocations.
1001
1002 template<int size, bool big_endian>
1003 void
1004 Sized_relobj<size, big_endian>::initialize_input_to_output_maps()
1005 {
1006   const unsigned int loccount = this->local_symbol_count_;
1007   for (unsigned int i = 1; i < loccount; ++i)
1008     {
1009       Symbol_value<size>& lv(this->local_values_[i]);
1010       lv.initialize_input_to_output_map(this);
1011     }
1012 }
1013
1014 // Free merge hash tables for the local symbols.
1015
1016 template<int size, bool big_endian>
1017 void
1018 Sized_relobj<size, big_endian>::free_input_to_output_maps()
1019 {
1020   const unsigned int loccount = this->local_symbol_count_;
1021   for (unsigned int i = 1; i < loccount; ++i)
1022     {
1023       Symbol_value<size>& lv(this->local_values_[i]);
1024       lv.free_input_to_output_map();
1025     }
1026 }
1027
1028 // If an object was compiled with -fsplit-stack, this is called to
1029 // check whether any relocations refer to functions defined in objects
1030 // which were not compiled with -fsplit-stack.  If they were, then we
1031 // need to apply some target-specific adjustments to request
1032 // additional stack space.
1033
1034 template<int size, bool big_endian>
1035 void
1036 Sized_relobj<size, big_endian>::split_stack_adjust(
1037     const Symbol_table* symtab,
1038     const unsigned char* pshdrs,
1039     unsigned int sh_type,
1040     unsigned int shndx,
1041     const unsigned char* prelocs,
1042     size_t reloc_count,
1043     unsigned char* view,
1044     section_size_type view_size,
1045     Reloc_symbol_changes** reloc_map)
1046 {
1047   if (sh_type == elfcpp::SHT_REL)
1048     this->split_stack_adjust_reltype<elfcpp::SHT_REL>(symtab, pshdrs, shndx,
1049                                                       prelocs, reloc_count,
1050                                                       view, view_size,
1051                                                       reloc_map);
1052   else
1053     {
1054       gold_assert(sh_type == elfcpp::SHT_RELA);
1055       this->split_stack_adjust_reltype<elfcpp::SHT_RELA>(symtab, pshdrs, shndx,
1056                                                          prelocs, reloc_count,
1057                                                          view, view_size,
1058                                                          reloc_map);
1059     }
1060 }
1061
1062 // Adjust for -fsplit-stack, templatized on the type of the relocation
1063 // section.
1064
1065 template<int size, bool big_endian>
1066 template<int sh_type>
1067 void
1068 Sized_relobj<size, big_endian>::split_stack_adjust_reltype(
1069     const Symbol_table* symtab,
1070     const unsigned char* pshdrs,
1071     unsigned int shndx,
1072     const unsigned char* prelocs,
1073     size_t reloc_count,
1074     unsigned char* view,
1075     section_size_type view_size,
1076     Reloc_symbol_changes** reloc_map)
1077 {
1078   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
1079   const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
1080
1081   size_t local_count = this->local_symbol_count();
1082
1083   std::vector<section_offset_type> non_split_refs;
1084
1085   const unsigned char* pr = prelocs;
1086   for (size_t i = 0; i < reloc_count; ++i, pr += reloc_size)
1087     {
1088       Reltype reloc(pr);
1089
1090       typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info();
1091       unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
1092       if (r_sym < local_count)
1093         continue;
1094
1095       const Symbol* gsym = this->global_symbol(r_sym);
1096       gold_assert(gsym != NULL);
1097       if (gsym->is_forwarder())
1098         gsym = symtab->resolve_forwards(gsym);
1099
1100       // See if this relocation refers to a function defined in an
1101       // object compiled without -fsplit-stack.  Note that we don't
1102       // care about the type of relocation--this means that in some
1103       // cases we will ask for a large stack unnecessarily, but this
1104       // is not fatal.  FIXME: Some targets have symbols which are
1105       // functions but are not type STT_FUNC, e.g., STT_ARM_TFUNC.
1106       if (gsym->type() == elfcpp::STT_FUNC
1107           && !gsym->is_undefined()
1108           && gsym->source() == Symbol::FROM_OBJECT
1109           && !gsym->object()->uses_split_stack())
1110         {
1111           section_offset_type offset =
1112             convert_to_section_size_type(reloc.get_r_offset());
1113           non_split_refs.push_back(offset);
1114         }
1115     }
1116
1117   if (non_split_refs.empty())
1118     return;
1119
1120   // At this point, every entry in NON_SPLIT_REFS indicates a
1121   // relocation which refers to a function in an object compiled
1122   // without -fsplit-stack.  We now have to convert that list into a
1123   // set of offsets to functions.  First, we find all the functions.
1124
1125   Function_offsets function_offsets;
1126   this->find_functions(pshdrs, shndx, &function_offsets);
1127   if (function_offsets.empty())
1128     return;
1129
1130   // Now get a list of the function with references to non split-stack
1131   // code.
1132
1133   Function_offsets calls_non_split;
1134   for (std::vector<section_offset_type>::const_iterator p
1135          = non_split_refs.begin();
1136        p != non_split_refs.end();
1137        ++p)
1138     {
1139       Function_offsets::const_iterator low = function_offsets.lower_bound(*p);
1140       if (low == function_offsets.end())
1141         --low;
1142       else if (low->first == *p)
1143         ;
1144       else if (low == function_offsets.begin())
1145         continue;
1146       else
1147         --low;
1148
1149       calls_non_split.insert(*low);
1150     }
1151   if (calls_non_split.empty())
1152     return;
1153
1154   // Now we have a set of functions to adjust.  The adjustments are
1155   // target specific.  Besides changing the output section view
1156   // however, it likes, the target may request a relocation change
1157   // from one global symbol name to another.
1158
1159   for (Function_offsets::const_iterator p = calls_non_split.begin();
1160        p != calls_non_split.end();
1161        ++p)
1162     {
1163       std::string from;
1164       std::string to;
1165       parameters->target().calls_non_split(this, shndx, p->first, p->second,
1166                                            view, view_size, &from, &to);
1167       if (!from.empty())
1168         {
1169           gold_assert(!to.empty());
1170           Symbol* tosym = NULL;
1171
1172           // Find relocations in the relevant function which are for
1173           // FROM.
1174           pr = prelocs;
1175           for (size_t i = 0; i < reloc_count; ++i, pr += reloc_size)
1176             {
1177               Reltype reloc(pr);
1178
1179               typename elfcpp::Elf_types<size>::Elf_WXword r_info =
1180                 reloc.get_r_info();
1181               unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
1182               if (r_sym < local_count)
1183                 continue;
1184
1185               section_offset_type offset =
1186                 convert_to_section_size_type(reloc.get_r_offset());
1187               if (offset < p->first
1188                   || (offset
1189                       >= (p->first
1190                           + static_cast<section_offset_type>(p->second))))
1191                 continue;
1192
1193               const Symbol* gsym = this->global_symbol(r_sym);
1194               if (from == gsym->name())
1195                 {
1196                   if (tosym == NULL)
1197                     {
1198                       tosym = symtab->lookup(to.c_str());
1199                       if (tosym == NULL)
1200                         {
1201                           this->error(_("could not convert call "
1202                                         "to '%s' to '%s'"),
1203                                       from.c_str(), to.c_str());
1204                           break;
1205                         }
1206                     }
1207
1208                   if (*reloc_map == NULL)
1209                     *reloc_map = new Reloc_symbol_changes(reloc_count);
1210                   (*reloc_map)->set(i, tosym);
1211                 }
1212             }
1213         }
1214     }
1215 }
1216
1217 // Find all the function in this object defined in section SHNDX.
1218 // Store their offsets in the section in FUNCTION_OFFSETS.
1219
1220 template<int size, bool big_endian>
1221 void
1222 Sized_relobj<size, big_endian>::find_functions(
1223     const unsigned char* pshdrs,
1224     unsigned int shndx,
1225     Sized_relobj<size, big_endian>::Function_offsets* function_offsets)
1226 {
1227   // We need to read the symbols to find the functions.  If we wanted
1228   // to, we could cache reading the symbols across all sections in the
1229   // object.
1230   const unsigned int symtab_shndx = this->symtab_shndx_;
1231   typename This::Shdr symtabshdr(pshdrs + symtab_shndx * This::shdr_size);
1232   gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
1233
1234   typename elfcpp::Elf_types<size>::Elf_WXword sh_size =
1235     symtabshdr.get_sh_size();
1236   const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
1237                                               sh_size, true, true);
1238
1239   const int sym_size = This::sym_size;
1240   const unsigned int symcount = sh_size / sym_size;
1241   for (unsigned int i = 0; i < symcount; ++i, psyms += sym_size)
1242     {
1243       typename elfcpp::Sym<size, big_endian> isym(psyms);
1244
1245       // FIXME: Some targets can have functions which do not have type
1246       // STT_FUNC, e.g., STT_ARM_TFUNC.
1247       if (isym.get_st_type() != elfcpp::STT_FUNC
1248           || isym.get_st_size() == 0)
1249         continue;
1250
1251       bool is_ordinary;
1252       unsigned int sym_shndx = this->adjust_sym_shndx(i, isym.get_st_shndx(),
1253                                                       &is_ordinary);
1254       if (!is_ordinary || sym_shndx != shndx)
1255         continue;
1256
1257       section_offset_type value =
1258         convert_to_section_size_type(isym.get_st_value());
1259       section_size_type fnsize =
1260         convert_to_section_size_type(isym.get_st_size());
1261
1262       (*function_offsets)[value] = fnsize;
1263     }
1264 }
1265
1266 // Class Merged_symbol_value.
1267
1268 template<int size>
1269 void
1270 Merged_symbol_value<size>::initialize_input_to_output_map(
1271     const Relobj* object,
1272     unsigned int input_shndx)
1273 {
1274   Object_merge_map* map = object->merge_map();
1275   map->initialize_input_to_output_map<size>(input_shndx,
1276                                             this->output_start_address_,
1277                                             &this->output_addresses_);
1278 }
1279
1280 // Get the output value corresponding to an input offset if we
1281 // couldn't find it in the hash table.
1282
1283 template<int size>
1284 typename elfcpp::Elf_types<size>::Elf_Addr
1285 Merged_symbol_value<size>::value_from_output_section(
1286     const Relobj* object,
1287     unsigned int input_shndx,
1288     typename elfcpp::Elf_types<size>::Elf_Addr input_offset) const
1289 {
1290   section_offset_type output_offset;
1291   bool found = object->merge_map()->get_output_offset(NULL, input_shndx,
1292                                                       input_offset,
1293                                                       &output_offset);
1294
1295   // If this assertion fails, it means that some relocation was
1296   // against a portion of an input merge section which we didn't map
1297   // to the output file and we didn't explicitly discard.  We should
1298   // always map all portions of input merge sections.
1299   gold_assert(found);
1300
1301   if (output_offset == -1)
1302     return 0;
1303   else
1304     return this->output_start_address_ + output_offset;
1305 }
1306
1307 // Track_relocs methods.
1308
1309 // Initialize the class to track the relocs.  This gets the object,
1310 // the reloc section index, and the type of the relocs.  This returns
1311 // false if something goes wrong.
1312
1313 template<int size, bool big_endian>
1314 bool
1315 Track_relocs<size, big_endian>::initialize(
1316     Object* object,
1317     unsigned int reloc_shndx,
1318     unsigned int reloc_type)
1319 {
1320   // If RELOC_SHNDX is -1U, it means there is more than one reloc
1321   // section for the .eh_frame section.  We can't handle that case.
1322   if (reloc_shndx == -1U)
1323     return false;
1324
1325   // If RELOC_SHNDX is 0, there is no reloc section.
1326   if (reloc_shndx == 0)
1327     return true;
1328
1329   // Get the contents of the reloc section.
1330   this->prelocs_ = object->section_contents(reloc_shndx, &this->len_, false);
1331
1332   if (reloc_type == elfcpp::SHT_REL)
1333     this->reloc_size_ = elfcpp::Elf_sizes<size>::rel_size;
1334   else if (reloc_type == elfcpp::SHT_RELA)
1335     this->reloc_size_ = elfcpp::Elf_sizes<size>::rela_size;
1336   else
1337     gold_unreachable();
1338
1339   if (this->len_ % this->reloc_size_ != 0)
1340     {
1341       object->error(_("reloc section size %zu is not a multiple of "
1342                       "reloc size %d\n"),
1343                     static_cast<size_t>(this->len_),
1344                     this->reloc_size_);
1345       return false;
1346     }
1347
1348   return true;
1349 }
1350
1351 // Return the offset of the next reloc, or -1 if there isn't one.
1352
1353 template<int size, bool big_endian>
1354 off_t
1355 Track_relocs<size, big_endian>::next_offset() const
1356 {
1357   if (this->pos_ >= this->len_)
1358     return -1;
1359
1360   // Rel and Rela start out the same, so we can always use Rel to find
1361   // the r_offset value.
1362   elfcpp::Rel<size, big_endian> rel(this->prelocs_ + this->pos_);
1363   return rel.get_r_offset();
1364 }
1365
1366 // Return the index of the symbol referenced by the next reloc, or -1U
1367 // if there aren't any more relocs.
1368
1369 template<int size, bool big_endian>
1370 unsigned int
1371 Track_relocs<size, big_endian>::next_symndx() const
1372 {
1373   if (this->pos_ >= this->len_)
1374     return -1U;
1375
1376   // Rel and Rela start out the same, so we can use Rel to find the
1377   // symbol index.
1378   elfcpp::Rel<size, big_endian> rel(this->prelocs_ + this->pos_);
1379   return elfcpp::elf_r_sym<size>(rel.get_r_info());
1380 }
1381
1382 // Advance to the next reloc whose r_offset is greater than or equal
1383 // to OFFSET.  Return the number of relocs we skip.
1384
1385 template<int size, bool big_endian>
1386 int
1387 Track_relocs<size, big_endian>::advance(off_t offset)
1388 {
1389   int ret = 0;
1390   while (this->pos_ < this->len_)
1391     {
1392       // Rel and Rela start out the same, so we can always use Rel to
1393       // find the r_offset value.
1394       elfcpp::Rel<size, big_endian> rel(this->prelocs_ + this->pos_);
1395       if (static_cast<off_t>(rel.get_r_offset()) >= offset)
1396         break;
1397       ++ret;
1398       this->pos_ += this->reloc_size_;
1399     }
1400   return ret;
1401 }
1402
1403 // Instantiate the templates we need.
1404
1405 #ifdef HAVE_TARGET_32_LITTLE
1406 template
1407 void
1408 Sized_relobj<32, false>::do_read_relocs(Read_relocs_data* rd);
1409 #endif
1410
1411 #ifdef HAVE_TARGET_32_BIG
1412 template
1413 void
1414 Sized_relobj<32, true>::do_read_relocs(Read_relocs_data* rd);
1415 #endif
1416
1417 #ifdef HAVE_TARGET_64_LITTLE
1418 template
1419 void
1420 Sized_relobj<64, false>::do_read_relocs(Read_relocs_data* rd);
1421 #endif
1422
1423 #ifdef HAVE_TARGET_64_BIG
1424 template
1425 void
1426 Sized_relobj<64, true>::do_read_relocs(Read_relocs_data* rd);
1427 #endif
1428
1429 #ifdef HAVE_TARGET_32_LITTLE
1430 template
1431 void
1432 Sized_relobj<32, false>::do_gc_process_relocs(const General_options& options,
1433                                         Symbol_table* symtab,
1434                                         Layout* layout,
1435                                         Read_relocs_data* rd);
1436 #endif
1437
1438 #ifdef HAVE_TARGET_32_BIG
1439 template
1440 void
1441 Sized_relobj<32, true>::do_gc_process_relocs(const General_options& options,
1442                                        Symbol_table* symtab,
1443                                        Layout* layout,
1444                                        Read_relocs_data* rd);
1445 #endif
1446
1447 #ifdef HAVE_TARGET_64_LITTLE
1448 template
1449 void
1450 Sized_relobj<64, false>::do_gc_process_relocs(const General_options& options,
1451                                         Symbol_table* symtab,
1452                                         Layout* layout,
1453                                         Read_relocs_data* rd);
1454 #endif
1455
1456 #ifdef HAVE_TARGET_64_BIG
1457 template
1458 void
1459 Sized_relobj<64, true>::do_gc_process_relocs(const General_options& options,
1460                                        Symbol_table* symtab,
1461                                        Layout* layout,
1462                                        Read_relocs_data* rd);
1463 #endif
1464
1465 #ifdef HAVE_TARGET_32_LITTLE
1466 template
1467 void
1468 Sized_relobj<32, false>::do_scan_relocs(const General_options& options,
1469                                         Symbol_table* symtab,
1470                                         Layout* layout,
1471                                         Read_relocs_data* rd);
1472 #endif
1473
1474 #ifdef HAVE_TARGET_32_BIG
1475 template
1476 void
1477 Sized_relobj<32, true>::do_scan_relocs(const General_options& options,
1478                                        Symbol_table* symtab,
1479                                        Layout* layout,
1480                                        Read_relocs_data* rd);
1481 #endif
1482
1483 #ifdef HAVE_TARGET_64_LITTLE
1484 template
1485 void
1486 Sized_relobj<64, false>::do_scan_relocs(const General_options& options,
1487                                         Symbol_table* symtab,
1488                                         Layout* layout,
1489                                         Read_relocs_data* rd);
1490 #endif
1491
1492 #ifdef HAVE_TARGET_64_BIG
1493 template
1494 void
1495 Sized_relobj<64, true>::do_scan_relocs(const General_options& options,
1496                                        Symbol_table* symtab,
1497                                        Layout* layout,
1498                                        Read_relocs_data* rd);
1499 #endif
1500
1501 #ifdef HAVE_TARGET_32_LITTLE
1502 template
1503 void
1504 Sized_relobj<32, false>::do_relocate(const General_options& options,
1505                                      const Symbol_table* symtab,
1506                                      const Layout* layout,
1507                                      Output_file* of);
1508 #endif
1509
1510 #ifdef HAVE_TARGET_32_BIG
1511 template
1512 void
1513 Sized_relobj<32, true>::do_relocate(const General_options& options,
1514                                     const Symbol_table* symtab,
1515                                     const Layout* layout,
1516                                     Output_file* of);
1517 #endif
1518
1519 #ifdef HAVE_TARGET_64_LITTLE
1520 template
1521 void
1522 Sized_relobj<64, false>::do_relocate(const General_options& options,
1523                                      const Symbol_table* symtab,
1524                                      const Layout* layout,
1525                                      Output_file* of);
1526 #endif
1527
1528 #ifdef HAVE_TARGET_64_BIG
1529 template
1530 void
1531 Sized_relobj<64, true>::do_relocate(const General_options& options,
1532                                     const Symbol_table* symtab,
1533                                     const Layout* layout,
1534                                     Output_file* of);
1535 #endif
1536
1537 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
1538 template
1539 class Merged_symbol_value<32>;
1540 #endif
1541
1542 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
1543 template
1544 class Merged_symbol_value<64>;
1545 #endif
1546
1547 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
1548 template
1549 class Symbol_value<32>;
1550 #endif
1551
1552 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
1553 template
1554 class Symbol_value<64>;
1555 #endif
1556
1557 #ifdef HAVE_TARGET_32_LITTLE
1558 template
1559 class Track_relocs<32, false>;
1560 #endif
1561
1562 #ifdef HAVE_TARGET_32_BIG
1563 template
1564 class Track_relocs<32, true>;
1565 #endif
1566
1567 #ifdef HAVE_TARGET_64_LITTLE
1568 template
1569 class Track_relocs<64, false>;
1570 #endif
1571
1572 #ifdef HAVE_TARGET_64_BIG
1573 template
1574 class Track_relocs<64, true>;
1575 #endif
1576
1577 } // End namespace gold.