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