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