gold/layout.cc

   1 // layout.cc -- lay out output file sections for gold
   2
   3 #include "gold.h"
   4
   5 #include <cstring>
   6 #include <algorithm>
   7 #include <iostream>
   8 #include <utility>
   9
  10 #include "output.h"
  11 #include "symtab.h"
  12 #include "dynobj.h"
  13 #include "layout.h"
  14
  15 namespace gold
  16 {
  17
  18 // Layout_task_runner methods.
  19
  20 // Lay out the sections.  This is called after all the input objects
  21 // have been read.
  22
  23 void
  24 Layout_task_runner::run(Workqueue* workqueue)
  25 {
  26   off_t file_size = this->layout_->finalize(this->input_objects_,
  27                                             this->symtab_);
  28
  29   // Now we know the final size of the output file and we know where
  30   // each piece of information goes.
  31   Output_file* of = new Output_file(this->options_);
  32   of->open(file_size);
  33
  34   // Queue up the final set of tasks.
  35   gold::queue_final_tasks(this->options_, this->input_objects_,
  36                           this->symtab_, this->layout_, workqueue, of);
  37 }
  38
  39 // Layout methods.
  40
  41 Layout::Layout(const General_options& options)
  42   : options_(options), namepool_(), sympool_(), dynpool_(), signatures_(),
  43     section_name_map_(), segment_list_(), section_list_(),
  44     unattached_section_list_(), special_output_list_(),
  45     tls_segment_(NULL), symtab_section_(NULL),
  46     dynsym_section_(NULL), dynamic_section_(NULL), dynamic_data_(NULL)
  47 {
  48   // Make space for more than enough segments for a typical file.
  49   // This is just for efficiency--it's OK if we wind up needing more.
  50   this->segment_list_.reserve(12);
  51
  52   // We expect three unattached Output_data objects: the file header,
  53   // the segment headers, and the section headers.
  54   this->special_output_list_.reserve(3);
  55 }
  56
  57 // Hash a key we use to look up an output section mapping.
  58
  59 size_t
  60 Layout::Hash_key::operator()(const Layout::Key& k) const
  61 {
  62  return k.first + k.second.first + k.second.second;
  63 }
  64
  65 // Whether to include this section in the link.
  66
  67 template<int size, bool big_endian>
  68 bool
  69 Layout::include_section(Object*, const char*,
  70                         const elfcpp::Shdr<size, big_endian>& shdr)
  71 {
  72   // Some section types are never linked.  Some are only linked when
  73   // doing a relocateable link.
  74   switch (shdr.get_sh_type())
  75     {
  76     case elfcpp::SHT_NULL:
  77     case elfcpp::SHT_SYMTAB:
  78     case elfcpp::SHT_DYNSYM:
  79     case elfcpp::SHT_STRTAB:
  80     case elfcpp::SHT_HASH:
  81     case elfcpp::SHT_DYNAMIC:
  82     case elfcpp::SHT_SYMTAB_SHNDX:
  83       return false;
  84
  85     case elfcpp::SHT_RELA:
  86     case elfcpp::SHT_REL:
  87     case elfcpp::SHT_GROUP:
  88       return this->options_.is_relocatable();
  89
  90     default:
  91       // FIXME: Handle stripping debug sections here.
  92       return true;
  93     }
  94 }
  95
  96 // Return an output section named NAME, or NULL if there is none.
  97
  98 Output_section*
  99 Layout::find_output_section(const char* name) const
 100 {
 101   for (Section_name_map::const_iterator p = this->section_name_map_.begin();
 102        p != this->section_name_map_.end();
 103        ++p)
 104     if (strcmp(p->second->name(), name) == 0)
 105       return p->second;
 106   return NULL;
 107 }
 108
 109 // Return an output segment of type TYPE, with segment flags SET set
 110 // and segment flags CLEAR clear.  Return NULL if there is none.
 111
 112 Output_segment*
 113 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
 114                             elfcpp::Elf_Word clear) const
 115 {
 116   for (Segment_list::const_iterator p = this->segment_list_.begin();
 117        p != this->segment_list_.end();
 118        ++p)
 119     if (static_cast<elfcpp::PT>((*p)->type()) == type
 120         && ((*p)->flags() & set) == set
 121         && ((*p)->flags() & clear) == 0)
 122       return *p;
 123   return NULL;
 124 }
 125
 126 // Return the output section to use for section NAME with type TYPE
 127 // and section flags FLAGS.
 128
 129 Output_section*
 130 Layout::get_output_section(const char* name, Stringpool::Key name_key,
 131                            elfcpp::Elf_Word type, elfcpp::Elf_Xword flags)
 132 {
 133   // We should ignore some flags.
 134   flags &= ~ (elfcpp::SHF_INFO_LINK
 135               | elfcpp::SHF_LINK_ORDER
 136               | elfcpp::SHF_GROUP);
 137
 138   const Key key(name_key, std::make_pair(type, flags));
 139   const std::pair<Key, Output_section*> v(key, NULL);
 140   std::pair<Section_name_map::iterator, bool> ins(
 141     this->section_name_map_.insert(v));
 142
 143   if (!ins.second)
 144     return ins.first->second;
 145   else
 146     {
 147       // This is the first time we've seen this name/type/flags
 148       // combination.
 149       Output_section* os = this->make_output_section(name, type, flags);
 150       ins.first->second = os;
 151       return os;
 152     }
 153 }
 154
 155 // Return the output section to use for input section SHNDX, with name
 156 // NAME, with header HEADER, from object OBJECT.  Set *OFF to the
 157 // offset of this input section without the output section.
 158
 159 template<int size, bool big_endian>
 160 Output_section*
 161 Layout::layout(Relobj* object, unsigned int shndx, const char* name,
 162                const elfcpp::Shdr<size, big_endian>& shdr, off_t* off)
 163 {
 164   if (!this->include_section(object, name, shdr))
 165     return NULL;
 166
 167   // If we are not doing a relocateable link, choose the name to use
 168   // for the output section.
 169   size_t len = strlen(name);
 170   if (!this->options_.is_relocatable())
 171     name = Layout::output_section_name(name, &len);
 172
 173   // FIXME: Handle SHF_OS_NONCONFORMING here.
 174
 175   // Canonicalize the section name.
 176   Stringpool::Key name_key;
 177   name = this->namepool_.add(name, len, &name_key);
 178
 179   // Find the output section.  The output section is selected based on
 180   // the section name, type, and flags.
 181   Output_section* os = this->get_output_section(name, name_key,
 182                                                 shdr.get_sh_type(),
 183                                                 shdr.get_sh_flags());
 184
 185   // FIXME: Handle SHF_LINK_ORDER somewhere.
 186
 187   *off = os->add_input_section(object, shndx, name, shdr);
 188
 189   return os;
 190 }
 191
 192 // Add POSD to an output section using NAME, TYPE, and FLAGS.
 193
 194 void
 195 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
 196                                 elfcpp::Elf_Xword flags,
 197                                 Output_section_data* posd)
 198 {
 199   // Canonicalize the name.
 200   Stringpool::Key name_key;
 201   name = this->namepool_.add(name, &name_key);
 202
 203   Output_section* os = this->get_output_section(name, name_key, type, flags);
 204   os->add_output_section_data(posd);
 205 }
 206
 207 // Map section flags to segment flags.
 208
 209 elfcpp::Elf_Word
 210 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
 211 {
 212   elfcpp::Elf_Word ret = elfcpp::PF_R;
 213   if ((flags & elfcpp::SHF_WRITE) != 0)
 214     ret |= elfcpp::PF_W;
 215   if ((flags & elfcpp::SHF_EXECINSTR) != 0)
 216     ret |= elfcpp::PF_X;
 217   return ret;
 218 }
 219
 220 // Make a new Output_section, and attach it to segments as
 221 // appropriate.
 222
 223 Output_section*
 224 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
 225                             elfcpp::Elf_Xword flags)
 226 {
 227   Output_section* os = new Output_section(name, type, flags, true);
 228   this->section_list_.push_back(os);
 229
 230   if ((flags & elfcpp::SHF_ALLOC) == 0)
 231     this->unattached_section_list_.push_back(os);
 232   else
 233     {
 234       // This output section goes into a PT_LOAD segment.
 235
 236       elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
 237
 238       // The only thing we really care about for PT_LOAD segments is
 239       // whether or not they are writable, so that is how we search
 240       // for them.  People who need segments sorted on some other
 241       // basis will have to wait until we implement a mechanism for
 242       // them to describe the segments they want.
 243
 244       Segment_list::const_iterator p;
 245       for (p = this->segment_list_.begin();
 246            p != this->segment_list_.end();
 247            ++p)
 248         {
 249           if ((*p)->type() == elfcpp::PT_LOAD
 250               && ((*p)->flags() & elfcpp::PF_W) == (seg_flags & elfcpp::PF_W))
 251             {
 252               (*p)->add_output_section(os, seg_flags);
 253               break;
 254             }
 255         }
 256
 257       if (p == this->segment_list_.end())
 258         {
 259           Output_segment* oseg = new Output_segment(elfcpp::PT_LOAD,
 260                                                     seg_flags);
 261           this->segment_list_.push_back(oseg);
 262           oseg->add_output_section(os, seg_flags);
 263         }
 264
 265       // If we see a loadable SHT_NOTE section, we create a PT_NOTE
 266       // segment.
 267       if (type == elfcpp::SHT_NOTE)
 268         {
 269           // See if we already have an equivalent PT_NOTE segment.
 270           for (p = this->segment_list_.begin();
 271                p != segment_list_.end();
 272                ++p)
 273             {
 274               if ((*p)->type() == elfcpp::PT_NOTE
 275                   && (((*p)->flags() & elfcpp::PF_W)
 276                       == (seg_flags & elfcpp::PF_W)))
 277                 {
 278                   (*p)->add_output_section(os, seg_flags);
 279                   break;
 280                 }
 281             }
 282
 283           if (p == this->segment_list_.end())
 284             {
 285               Output_segment* oseg = new Output_segment(elfcpp::PT_NOTE,
 286                                                         seg_flags);
 287               this->segment_list_.push_back(oseg);
 288               oseg->add_output_section(os, seg_flags);
 289             }
 290         }
 291
 292       // If we see a loadable SHF_TLS section, we create a PT_TLS
 293       // segment.  There can only be one such segment.
 294       if ((flags & elfcpp::SHF_TLS) != 0)
 295         {
 296           if (this->tls_segment_ == NULL)
 297             {
 298               this->tls_segment_ = new Output_segment(elfcpp::PT_TLS,
 299                                                       seg_flags);
 300               this->segment_list_.push_back(this->tls_segment_);
 301             }
 302           this->tls_segment_->add_output_section(os, seg_flags);
 303         }
 304     }
 305
 306   return os;
 307 }
 308
 309 // Create the dynamic sections which are needed before we read the
 310 // relocs.
 311
 312 void
 313 Layout::create_initial_dynamic_sections(const Input_objects* input_objects,
 314                                         Symbol_table* symtab)
 315 {
 316   if (!input_objects->any_dynamic())
 317     return;
 318
 319   const char* dynamic_name = this->namepool_.add(".dynamic", NULL);
 320   this->dynamic_section_ = this->make_output_section(dynamic_name,
 321                                                      elfcpp::SHT_DYNAMIC,
 322                                                      (elfcpp::SHF_ALLOC
 323                                                       | elfcpp::SHF_WRITE));
 324
 325   symtab->define_in_output_data(input_objects->target(), "_DYNAMIC", NULL,
 326                                 this->dynamic_section_, 0, 0,
 327                                 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
 328                                 elfcpp::STV_HIDDEN, 0, false, false);
 329
 330   this->dynamic_data_ =  new Output_data_dynamic(input_objects->target(),
 331                                                  &this->dynpool_);
 332
 333   this->dynamic_section_->add_output_section_data(this->dynamic_data_);
 334 }
 335
 336 // Find the first read-only PT_LOAD segment, creating one if
 337 // necessary.
 338
 339 Output_segment*
 340 Layout::find_first_load_seg()
 341 {
 342   for (Segment_list::const_iterator p = this->segment_list_.begin();
 343        p != this->segment_list_.end();
 344        ++p)
 345     {
 346       if ((*p)->type() == elfcpp::PT_LOAD
 347           && ((*p)->flags() & elfcpp::PF_R) != 0
 348           && ((*p)->flags() & elfcpp::PF_W) == 0)
 349         return *p;
 350     }
 351
 352   Output_segment* load_seg = new Output_segment(elfcpp::PT_LOAD, elfcpp::PF_R);
 353   this->segment_list_.push_back(load_seg);
 354   return load_seg;
 355 }
 356
 357 // Finalize the layout.  When this is called, we have created all the
 358 // output sections and all the output segments which are based on
 359 // input sections.  We have several things to do, and we have to do
 360 // them in the right order, so that we get the right results correctly
 361 // and efficiently.
 362
 363 // 1) Finalize the list of output segments and create the segment
 364 // table header.
 365
 366 // 2) Finalize the dynamic symbol table and associated sections.
 367
 368 // 3) Determine the final file offset of all the output segments.
 369
 370 // 4) Determine the final file offset of all the SHF_ALLOC output
 371 // sections.
 372
 373 // 5) Create the symbol table sections and the section name table
 374 // section.
 375
 376 // 6) Finalize the symbol table: set symbol values to their final
 377 // value and make a final determination of which symbols are going
 378 // into the output symbol table.
 379
 380 // 7) Create the section table header.
 381
 382 // 8) Determine the final file offset of all the output sections which
 383 // are not SHF_ALLOC, including the section table header.
 384
 385 // 9) Finalize the ELF file header.
 386
 387 // This function returns the size of the output file.
 388
 389 off_t
 390 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab)
 391 {
 392   Target* const target = input_objects->target();
 393   const int size = target->get_size();
 394
 395   target->finalize_sections(&this->options_, this);
 396
 397   Output_segment* phdr_seg = NULL;
 398   if (input_objects->any_dynamic())
 399     {
 400       // There was a dynamic object in the link.  We need to create
 401       // some information for the dynamic linker.
 402
 403       // Create the PT_PHDR segment which will hold the program
 404       // headers.
 405       phdr_seg = new Output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
 406       this->segment_list_.push_back(phdr_seg);
 407
 408       // Create the dynamic symbol table, including the hash table.
 409       Output_section* dynstr;
 410       std::vector<Symbol*> dynamic_symbols;
 411       unsigned int local_dynamic_count;
 412       Versions versions;
 413       this->create_dynamic_symtab(target, symtab, &dynstr,
 414                                   &local_dynamic_count, &dynamic_symbols,
 415                                   &versions);
 416
 417       // Create the .interp section to hold the name of the
 418       // interpreter, and put it in a PT_INTERP segment.
 419       this->create_interp(target);
 420
 421       // Finish the .dynamic section to hold the dynamic data, and put
 422       // it in a PT_DYNAMIC segment.
 423       this->finish_dynamic_section(input_objects, symtab);
 424
 425       // We should have added everything we need to the dynamic string
 426       // table.
 427       this->dynpool_.set_string_offsets();
 428
 429       // Create the version sections.  We can't do this until the
 430       // dynamic string table is complete.
 431       this->create_version_sections(target, &versions, local_dynamic_count,
 432                                     dynamic_symbols, dynstr);
 433     }
 434
 435   // FIXME: Handle PT_GNU_STACK.
 436
 437   Output_segment* load_seg = this->find_first_load_seg();
 438
 439   // Lay out the segment headers.
 440   bool big_endian = target->is_big_endian();
 441   Output_segment_headers* segment_headers;
 442   segment_headers = new Output_segment_headers(size, big_endian,
 443                                                this->segment_list_);
 444   load_seg->add_initial_output_data(segment_headers);
 445   this->special_output_list_.push_back(segment_headers);
 446   if (phdr_seg != NULL)
 447     phdr_seg->add_initial_output_data(segment_headers);
 448
 449   // Lay out the file header.
 450   Output_file_header* file_header;
 451   file_header = new Output_file_header(size,
 452                                        big_endian,
 453                                        this->options_,
 454                                        target,
 455                                        symtab,
 456                                        segment_headers);
 457   load_seg->add_initial_output_data(file_header);
 458   this->special_output_list_.push_back(file_header);
 459
 460   // We set the output section indexes in set_segment_offsets and
 461   // set_section_offsets.
 462   unsigned int shndx = 1;
 463
 464   // Set the file offsets of all the segments, and all the sections
 465   // they contain.
 466   off_t off = this->set_segment_offsets(target, load_seg, &shndx);
 467
 468   // Create the symbol table sections.
 469   // FIXME: We don't need to do this if we are stripping symbols.
 470   this->create_symtab_sections(size, input_objects, symtab, &off);
 471
 472   // Create the .shstrtab section.
 473   Output_section* shstrtab_section = this->create_shstrtab();
 474
 475   // Set the file offsets of all the sections not associated with
 476   // segments.
 477   off = this->set_section_offsets(off, &shndx);
 478
 479   // Create the section table header.
 480   Output_section_headers* oshdrs = this->create_shdrs(size, big_endian, &off);
 481
 482   file_header->set_section_info(oshdrs, shstrtab_section);
 483
 484   // Now we know exactly where everything goes in the output file.
 485   Output_data::layout_complete();
 486
 487   return off;
 488 }
 489
 490 // Return whether SEG1 should be before SEG2 in the output file.  This
 491 // is based entirely on the segment type and flags.  When this is
 492 // called the segment addresses has normally not yet been set.
 493
 494 bool
 495 Layout::segment_precedes(const Output_segment* seg1,
 496                          const Output_segment* seg2)
 497 {
 498   elfcpp::Elf_Word type1 = seg1->type();
 499   elfcpp::Elf_Word type2 = seg2->type();
 500
 501   // The single PT_PHDR segment is required to precede any loadable
 502   // segment.  We simply make it always first.
 503   if (type1 == elfcpp::PT_PHDR)
 504     {
 505       gold_assert(type2 != elfcpp::PT_PHDR);
 506       return true;
 507     }
 508   if (type2 == elfcpp::PT_PHDR)
 509     return false;
 510
 511   // The single PT_INTERP segment is required to precede any loadable
 512   // segment.  We simply make it always second.
 513   if (type1 == elfcpp::PT_INTERP)
 514     {
 515       gold_assert(type2 != elfcpp::PT_INTERP);
 516       return true;
 517     }
 518   if (type2 == elfcpp::PT_INTERP)
 519     return false;
 520
 521   // We then put PT_LOAD segments before any other segments.
 522   if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
 523     return true;
 524   if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
 525     return false;
 526
 527   // We put the PT_TLS segment last, because that is where the dynamic
 528   // linker expects to find it (this is just for efficiency; other
 529   // positions would also work correctly).
 530   if (type1 == elfcpp::PT_TLS && type2 != elfcpp::PT_TLS)
 531     return false;
 532   if (type2 == elfcpp::PT_TLS && type1 != elfcpp::PT_TLS)
 533     return true;
 534
 535   const elfcpp::Elf_Word flags1 = seg1->flags();
 536   const elfcpp::Elf_Word flags2 = seg2->flags();
 537
 538   // The order of non-PT_LOAD segments is unimportant.  We simply sort
 539   // by the numeric segment type and flags values.  There should not
 540   // be more than one segment with the same type and flags.
 541   if (type1 != elfcpp::PT_LOAD)
 542     {
 543       if (type1 != type2)
 544         return type1 < type2;
 545       gold_assert(flags1 != flags2);
 546       return flags1 < flags2;
 547     }
 548
 549   // We sort PT_LOAD segments based on the flags.  Readonly segments
 550   // come before writable segments.  Then executable segments come
 551   // before non-executable segments.  Then the unlikely case of a
 552   // non-readable segment comes before the normal case of a readable
 553   // segment.  If there are multiple segments with the same type and
 554   // flags, we require that the address be set, and we sort by
 555   // virtual address and then physical address.
 556   if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
 557     return (flags1 & elfcpp::PF_W) == 0;
 558   if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
 559     return (flags1 & elfcpp::PF_X) != 0;
 560   if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
 561     return (flags1 & elfcpp::PF_R) == 0;
 562
 563   uint64_t vaddr1 = seg1->vaddr();
 564   uint64_t vaddr2 = seg2->vaddr();
 565   if (vaddr1 != vaddr2)
 566     return vaddr1 < vaddr2;
 567
 568   uint64_t paddr1 = seg1->paddr();
 569   uint64_t paddr2 = seg2->paddr();
 570   gold_assert(paddr1 != paddr2);
 571   return paddr1 < paddr2;
 572 }
 573
 574 // Set the file offsets of all the segments, and all the sections they
 575 // contain.  They have all been created.  LOAD_SEG must be be laid out
 576 // first.  Return the offset of the data to follow.
 577
 578 off_t
 579 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
 580                             unsigned int *pshndx)
 581 {
 582   // Sort them into the final order.
 583   std::sort(this->segment_list_.begin(), this->segment_list_.end(),
 584             Layout::Compare_segments());
 585
 586   // Find the PT_LOAD segments, and set their addresses and offsets
 587   // and their section's addresses and offsets.
 588   uint64_t addr = target->text_segment_address();
 589   off_t off = 0;
 590   bool was_readonly = false;
 591   for (Segment_list::iterator p = this->segment_list_.begin();
 592        p != this->segment_list_.end();
 593        ++p)
 594     {
 595       if ((*p)->type() == elfcpp::PT_LOAD)
 596         {
 597           if (load_seg != NULL && load_seg != *p)
 598             gold_unreachable();
 599           load_seg = NULL;
 600
 601           // If the last segment was readonly, and this one is not,
 602           // then skip the address forward one page, maintaining the
 603           // same position within the page.  This lets us store both
 604           // segments overlapping on a single page in the file, but
 605           // the loader will put them on different pages in memory.
 606
 607           uint64_t orig_addr = addr;
 608           uint64_t orig_off = off;
 609
 610           uint64_t aligned_addr = addr;
 611           uint64_t abi_pagesize = target->abi_pagesize();
 612           if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0)
 613             {
 614               uint64_t align = (*p)->addralign();
 615
 616               addr = align_address(addr, align);
 617               aligned_addr = addr;
 618               if ((addr & (abi_pagesize - 1)) != 0)
 619                 addr = addr + abi_pagesize;
 620             }
 621
 622           unsigned int shndx_hold = *pshndx;
 623           off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
 624           uint64_t new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
 625
 626           // Now that we know the size of this segment, we may be able
 627           // to save a page in memory, at the cost of wasting some
 628           // file space, by instead aligning to the start of a new
 629           // page.  Here we use the real machine page size rather than
 630           // the ABI mandated page size.
 631
 632           if (aligned_addr != addr)
 633             {
 634               uint64_t common_pagesize = target->common_pagesize();
 635               uint64_t first_off = (common_pagesize
 636                                     - (aligned_addr
 637                                        & (common_pagesize - 1)));
 638               uint64_t last_off = new_addr & (common_pagesize - 1);
 639               if (first_off > 0
 640                   && last_off > 0
 641                   && ((aligned_addr & ~ (common_pagesize - 1))
 642                       != (new_addr & ~ (common_pagesize - 1)))
 643                   && first_off + last_off <= common_pagesize)
 644                 {
 645                   *pshndx = shndx_hold;
 646                   addr = align_address(aligned_addr, common_pagesize);
 647                   off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
 648                   new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
 649                 }
 650             }
 651
 652           addr = new_addr;
 653
 654           if (((*p)->flags() & elfcpp::PF_W) == 0)
 655             was_readonly = true;
 656         }
 657     }
 658
 659   // Handle the non-PT_LOAD segments, setting their offsets from their
 660   // section's offsets.
 661   for (Segment_list::iterator p = this->segment_list_.begin();
 662        p != this->segment_list_.end();
 663        ++p)
 664     {
 665       if ((*p)->type() != elfcpp::PT_LOAD)
 666         (*p)->set_offset();
 667     }
 668
 669   return off;
 670 }
 671
 672 // Set the file offset of all the sections not associated with a
 673 // segment.
 674
 675 off_t
 676 Layout::set_section_offsets(off_t off, unsigned int* pshndx)
 677 {
 678   for (Section_list::iterator p = this->unattached_section_list_.begin();
 679        p != this->unattached_section_list_.end();
 680        ++p)
 681     {
 682       (*p)->set_out_shndx(*pshndx);
 683       ++*pshndx;
 684       if ((*p)->offset() != -1)
 685         continue;
 686       off = align_address(off, (*p)->addralign());
 687       (*p)->set_address(0, off);
 688       off += (*p)->data_size();
 689     }
 690   return off;
 691 }
 692
 693 // Create the symbol table sections.
 694
 695 void
 696 Layout::create_symtab_sections(int size, const Input_objects* input_objects,
 697                                Symbol_table* symtab,
 698                                off_t* poff)
 699 {
 700   int symsize;
 701   unsigned int align;
 702   if (size == 32)
 703     {
 704       symsize = elfcpp::Elf_sizes<32>::sym_size;
 705       align = 4;
 706     }
 707   else if (size == 64)
 708     {
 709       symsize = elfcpp::Elf_sizes<64>::sym_size;
 710       align = 8;
 711     }
 712   else
 713     gold_unreachable();
 714
 715   off_t off = *poff;
 716   off = align_address(off, align);
 717   off_t startoff = off;
 718
 719   // Save space for the dummy symbol at the start of the section.  We
 720   // never bother to write this out--it will just be left as zero.
 721   off += symsize;
 722   unsigned int local_symbol_index = 1;
 723
 724   // Add STT_SECTION symbols for each Output section which needs one.
 725   for (Section_list::iterator p = this->section_list_.begin();
 726        p != this->section_list_.end();
 727        ++p)
 728     {
 729       if (!(*p)->needs_symtab_index())
 730         (*p)->set_symtab_index(-1U);
 731       else
 732         {
 733           (*p)->set_symtab_index(local_symbol_index);
 734           ++local_symbol_index;
 735           off += symsize;
 736         }
 737     }
 738
 739   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
 740        p != input_objects->relobj_end();
 741        ++p)
 742     {
 743       Task_lock_obj<Object> tlo(**p);
 744       unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
 745                                                         off,
 746                                                         &this->sympool_);
 747       off += (index - local_symbol_index) * symsize;
 748       local_symbol_index = index;
 749     }
 750
 751   unsigned int local_symcount = local_symbol_index;
 752   gold_assert(local_symcount * symsize == off - startoff);
 753
 754   off_t dynoff;
 755   size_t dyn_global_index;
 756   size_t dyncount;
 757   if (this->dynsym_section_ == NULL)
 758     {
 759       dynoff = 0;
 760       dyn_global_index = 0;
 761       dyncount = 0;
 762     }
 763   else
 764     {
 765       dyn_global_index = this->dynsym_section_->info();
 766       off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
 767       dynoff = this->dynsym_section_->offset() + locsize;
 768       dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
 769       gold_assert(dyncount * symsize
 770                   == this->dynsym_section_->data_size() - locsize);
 771     }
 772
 773   off = symtab->finalize(local_symcount, off, dynoff, dyn_global_index,
 774                          dyncount, &this->sympool_);
 775
 776   this->sympool_.set_string_offsets();
 777
 778   const char* symtab_name = this->namepool_.add(".symtab", NULL);
 779   Output_section* osymtab = this->make_output_section(symtab_name,
 780                                                       elfcpp::SHT_SYMTAB,
 781                                                       0);
 782   this->symtab_section_ = osymtab;
 783
 784   Output_section_data* pos = new Output_data_space(off - startoff,
 785                                                    align);
 786   osymtab->add_output_section_data(pos);
 787
 788   const char* strtab_name = this->namepool_.add(".strtab", NULL);
 789   Output_section* ostrtab = this->make_output_section(strtab_name,
 790                                                       elfcpp::SHT_STRTAB,
 791                                                       0);
 792
 793   Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
 794   ostrtab->add_output_section_data(pstr);
 795
 796   osymtab->set_address(0, startoff);
 797   osymtab->set_link_section(ostrtab);
 798   osymtab->set_info(local_symcount);
 799   osymtab->set_entsize(symsize);
 800
 801   *poff = off;
 802 }
 803
 804 // Create the .shstrtab section, which holds the names of the
 805 // sections.  At the time this is called, we have created all the
 806 // output sections except .shstrtab itself.
 807
 808 Output_section*
 809 Layout::create_shstrtab()
 810 {
 811   // FIXME: We don't need to create a .shstrtab section if we are
 812   // stripping everything.
 813
 814   const char* name = this->namepool_.add(".shstrtab", NULL);
 815
 816   this->namepool_.set_string_offsets();
 817
 818   Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0);
 819
 820   Output_section_data* posd = new Output_data_strtab(&this->namepool_);
 821   os->add_output_section_data(posd);
 822
 823   return os;
 824 }
 825
 826 // Create the section headers.  SIZE is 32 or 64.  OFF is the file
 827 // offset.
 828
 829 Output_section_headers*
 830 Layout::create_shdrs(int size, bool big_endian, off_t* poff)
 831 {
 832   Output_section_headers* oshdrs;
 833   oshdrs = new Output_section_headers(size, big_endian, this,
 834                                       &this->segment_list_,
 835                                       &this->unattached_section_list_,
 836                                       &this->namepool_);
 837   off_t off = align_address(*poff, oshdrs->addralign());
 838   oshdrs->set_address(0, off);
 839   off += oshdrs->data_size();
 840   *poff = off;
 841   this->special_output_list_.push_back(oshdrs);
 842   return oshdrs;
 843 }
 844
 845 // Create the dynamic symbol table.
 846
 847 void
 848 Layout::create_dynamic_symtab(const Target* target, Symbol_table* symtab,
 849                               Output_section **pdynstr,
 850                               unsigned int* plocal_dynamic_count,
 851                               std::vector<Symbol*>* pdynamic_symbols,
 852                               Versions* pversions)
 853 {
 854   // Count all the symbols in the dynamic symbol table, and set the
 855   // dynamic symbol indexes.
 856
 857   // Skip symbol 0, which is always all zeroes.
 858   unsigned int index = 1;
 859
 860   // Add STT_SECTION symbols for each Output section which needs one.
 861   for (Section_list::iterator p = this->section_list_.begin();
 862        p != this->section_list_.end();
 863        ++p)
 864     {
 865       if (!(*p)->needs_dynsym_index())
 866         (*p)->set_dynsym_index(-1U);
 867       else
 868         {
 869           (*p)->set_dynsym_index(index);
 870           ++index;
 871         }
 872     }
 873
 874   // FIXME: Some targets apparently require local symbols in the
 875   // dynamic symbol table.  Here is where we will have to count them,
 876   // and set the dynamic symbol indexes, and add the names to
 877   // this->dynpool_.
 878
 879   unsigned int local_symcount = index;
 880   *plocal_dynamic_count = local_symcount;
 881
 882   // FIXME: We have to tell set_dynsym_indexes whether the
 883   // -E/--export-dynamic option was used.
 884   index = symtab->set_dynsym_indexes(&this->options_, target, index,
 885                                      pdynamic_symbols, &this->dynpool_,
 886                                      pversions);
 887
 888   int symsize;
 889   unsigned int align;
 890   const int size = target->get_size();
 891   if (size == 32)
 892     {
 893       symsize = elfcpp::Elf_sizes<32>::sym_size;
 894       align = 4;
 895     }
 896   else if (size == 64)
 897     {
 898       symsize = elfcpp::Elf_sizes<64>::sym_size;
 899       align = 8;
 900     }
 901   else
 902     gold_unreachable();
 903
 904   // Create the dynamic symbol table section.
 905
 906   const char* dynsym_name = this->namepool_.add(".dynsym", NULL);
 907   Output_section* dynsym = this->make_output_section(dynsym_name,
 908                                                      elfcpp::SHT_DYNSYM,
 909                                                      elfcpp::SHF_ALLOC);
 910
 911   Output_section_data* odata = new Output_data_space(index * symsize,
 912                                                      align);
 913   dynsym->add_output_section_data(odata);
 914
 915   dynsym->set_info(local_symcount);
 916   dynsym->set_entsize(symsize);
 917   dynsym->set_addralign(align);
 918
 919   this->dynsym_section_ = dynsym;
 920
 921   Output_data_dynamic* const odyn = this->dynamic_data_;
 922   odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
 923   odyn->add_constant(elfcpp::DT_SYMENT, symsize);
 924
 925   // Create the dynamic string table section.
 926
 927   const char* dynstr_name = this->namepool_.add(".dynstr", NULL);
 928   Output_section* dynstr = this->make_output_section(dynstr_name,
 929                                                      elfcpp::SHT_STRTAB,
 930                                                      elfcpp::SHF_ALLOC);
 931
 932   Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
 933   dynstr->add_output_section_data(strdata);
 934
 935   dynsym->set_link_section(dynstr);
 936   this->dynamic_section_->set_link_section(dynstr);
 937
 938   odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
 939   odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
 940
 941   *pdynstr = dynstr;
 942
 943   // Create the hash tables.
 944
 945   // FIXME: We need an option to create a GNU hash table.
 946
 947   unsigned char* phash;
 948   unsigned int hashlen;
 949   Dynobj::create_elf_hash_table(target, *pdynamic_symbols, local_symcount,
 950                                 &phash, &hashlen);
 951
 952   const char* hash_name = this->namepool_.add(".hash", NULL);
 953   Output_section* hashsec = this->make_output_section(hash_name,
 954                                                       elfcpp::SHT_HASH,
 955                                                       elfcpp::SHF_ALLOC);
 956
 957   Output_section_data* hashdata = new Output_data_const_buffer(phash,
 958                                                                hashlen,
 959                                                                align);
 960   hashsec->add_output_section_data(hashdata);
 961
 962   hashsec->set_link_section(dynsym);
 963   hashsec->set_entsize(4);
 964
 965   odyn->add_section_address(elfcpp::DT_HASH, hashsec);
 966 }
 967
 968 // Create the version sections.
 969
 970 void
 971 Layout::create_version_sections(const Target* target, const Versions* versions,
 972                                 unsigned int local_symcount,
 973                                 const std::vector<Symbol*>& dynamic_symbols,
 974                                 const Output_section* dynstr)
 975 {
 976   if (!versions->any_defs() && !versions->any_needs())
 977     return;
 978
 979   if (target->get_size() == 32)
 980     {
 981       if (target->is_big_endian())
 982         this->sized_create_version_sections<32, true>(versions,
 983                                                       local_symcount,
 984                                                       dynamic_symbols,
 985                                                       dynstr);
 986       else
 987         this->sized_create_version_sections<32, false>(versions,
 988                                                        local_symcount,
 989                                                        dynamic_symbols,
 990                                                        dynstr);
 991     }
 992   else if (target->get_size() == 64)
 993     {
 994       if (target->is_big_endian())
 995         this->sized_create_version_sections<64, true>(versions,
 996                                                       local_symcount,
 997                                                       dynamic_symbols,
 998                                                       dynstr);
 999       else
1000         this->sized_create_version_sections<64, false>(versions,
1001                                                        local_symcount,
1002                                                        dynamic_symbols,
1003                                                        dynstr);
1004     }
1005   else
1006     gold_unreachable();
1007 }
1008
1009 // Create the version sections, sized version.
1010
1011 template<int size, bool big_endian>
1012 void
1013 Layout::sized_create_version_sections(
1014     const Versions* versions,
1015     unsigned int local_symcount,
1016     const std::vector<Symbol*>& dynamic_symbols,
1017     const Output_section* dynstr)
1018 {
1019   const char* vname = this->namepool_.add(".gnu.version", NULL);
1020   Output_section* vsec = this->make_output_section(vname,
1021                                                    elfcpp::SHT_GNU_versym,
1022                                                    elfcpp::SHF_ALLOC);
1023
1024   unsigned char* vbuf;
1025   unsigned int vsize;
1026   versions->symbol_section_contents<size, big_endian>(&this->dynpool_,
1027                                                       local_symcount,
1028                                                       dynamic_symbols,
1029                                                       &vbuf, &vsize);
1030
1031   Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2);
1032
1033   vsec->add_output_section_data(vdata);
1034   vsec->set_entsize(2);
1035   vsec->set_link_section(this->dynsym_section_);
1036
1037   Output_data_dynamic* const odyn = this->dynamic_data_;
1038   odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
1039
1040   if (versions->any_defs())
1041     {
1042       const char* vdname = this->namepool_.add(".gnu.version_d", NULL);
1043       Output_section *vdsec;
1044       vdsec = this->make_output_section(vdname, elfcpp::SHT_GNU_verdef,
1045                                         elfcpp::SHF_ALLOC);
1046
1047       unsigned char* vdbuf;
1048       unsigned int vdsize;
1049       unsigned int vdentries;
1050       versions->def_section_contents<size, big_endian>(&this->dynpool_,
1051                                                        &vdbuf, &vdsize,
1052                                                        &vdentries);
1053
1054       Output_section_data* vddata = new Output_data_const_buffer(vdbuf,
1055                                                                  vdsize,
1056                                                                  4);
1057
1058       vdsec->add_output_section_data(vddata);
1059       vdsec->set_link_section(dynstr);
1060       vdsec->set_info(vdentries);
1061
1062       odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
1063       odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
1064     }
1065
1066   if (versions->any_needs())
1067     {
1068       const char* vnname = this->namepool_.add(".gnu.version_r", NULL);
1069       Output_section* vnsec;
1070       vnsec = this->make_output_section(vnname, elfcpp::SHT_GNU_verneed,
1071                                         elfcpp::SHF_ALLOC);
1072
1073       unsigned char* vnbuf;
1074       unsigned int vnsize;
1075       unsigned int vnentries;
1076       versions->need_section_contents<size, big_endian>(&this->dynpool_,
1077                                                         &vnbuf, &vnsize,
1078                                                         &vnentries);
1079
1080       Output_section_data* vndata = new Output_data_const_buffer(vnbuf,
1081                                                                  vnsize,
1082                                                                  4);
1083
1084       vnsec->add_output_section_data(vndata);
1085       vnsec->set_link_section(dynstr);
1086       vnsec->set_info(vnentries);
1087
1088       odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
1089       odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
1090     }
1091 }
1092
1093 // Create the .interp section and PT_INTERP segment.
1094
1095 void
1096 Layout::create_interp(const Target* target)
1097 {
1098   const char* interp = this->options_.dynamic_linker();
1099   if (interp == NULL)
1100     {
1101       interp = target->dynamic_linker();
1102       gold_assert(interp != NULL);
1103     }
1104
1105   size_t len = strlen(interp) + 1;
1106
1107   Output_section_data* odata = new Output_data_const(interp, len, 1);
1108
1109   const char* interp_name = this->namepool_.add(".interp", NULL);
1110   Output_section* osec = this->make_output_section(interp_name,
1111                                                    elfcpp::SHT_PROGBITS,
1112                                                    elfcpp::SHF_ALLOC);
1113   osec->add_output_section_data(odata);
1114
1115   Output_segment* oseg = new Output_segment(elfcpp::PT_INTERP, elfcpp::PF_R);
1116   this->segment_list_.push_back(oseg);
1117   oseg->add_initial_output_section(osec, elfcpp::PF_R);
1118 }
1119
1120 // Finish the .dynamic section and PT_DYNAMIC segment.
1121
1122 void
1123 Layout::finish_dynamic_section(const Input_objects* input_objects,
1124                                const Symbol_table* symtab)
1125 {
1126   Output_segment* oseg = new Output_segment(elfcpp::PT_DYNAMIC,
1127                                             elfcpp::PF_R | elfcpp::PF_W);
1128   this->segment_list_.push_back(oseg);
1129   oseg->add_initial_output_section(this->dynamic_section_,
1130                                    elfcpp::PF_R | elfcpp::PF_W);
1131
1132   Output_data_dynamic* const odyn = this->dynamic_data_;
1133
1134   for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
1135        p != input_objects->dynobj_end();
1136        ++p)
1137     {
1138       // FIXME: Handle --as-needed.
1139       odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
1140     }
1141
1142   // FIXME: Support --init and --fini.
1143   Symbol* sym = symtab->lookup("_init");
1144   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
1145     odyn->add_symbol(elfcpp::DT_INIT, sym);
1146
1147   sym = symtab->lookup("_fini");
1148   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
1149     odyn->add_symbol(elfcpp::DT_FINI, sym);
1150
1151   // FIXME: Support DT_INIT_ARRAY and DT_FINI_ARRAY.
1152 }
1153
1154 // The mapping of .gnu.linkonce section names to real section names.
1155
1156 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
1157 const Layout::Linkonce_mapping Layout::linkonce_mapping[] =
1158 {
1159   MAPPING_INIT("d.rel.ro", ".data.rel.ro"),     // Must be before "d".
1160   MAPPING_INIT("t", ".text"),
1161   MAPPING_INIT("r", ".rodata"),
1162   MAPPING_INIT("d", ".data"),
1163   MAPPING_INIT("b", ".bss"),
1164   MAPPING_INIT("s", ".sdata"),
1165   MAPPING_INIT("sb", ".sbss"),
1166   MAPPING_INIT("s2", ".sdata2"),
1167   MAPPING_INIT("sb2", ".sbss2"),
1168   MAPPING_INIT("wi", ".debug_info"),
1169   MAPPING_INIT("td", ".tdata"),
1170   MAPPING_INIT("tb", ".tbss"),
1171   MAPPING_INIT("lr", ".lrodata"),
1172   MAPPING_INIT("l", ".ldata"),
1173   MAPPING_INIT("lb", ".lbss"),
1174 };
1175 #undef MAPPING_INIT
1176
1177 const int Layout::linkonce_mapping_count =
1178   sizeof(Layout::linkonce_mapping) / sizeof(Layout::linkonce_mapping[0]);
1179
1180 // Return the name of the output section to use for a .gnu.linkonce
1181 // section.  This is based on the default ELF linker script of the old
1182 // GNU linker.  For example, we map a name like ".gnu.linkonce.t.foo"
1183 // to ".text".  Set *PLEN to the length of the name.  *PLEN is
1184 // initialized to the length of NAME.
1185
1186 const char*
1187 Layout::linkonce_output_name(const char* name, size_t *plen)
1188 {
1189   const char* s = name + sizeof(".gnu.linkonce") - 1;
1190   if (*s != '.')
1191     return name;
1192   ++s;
1193   const Linkonce_mapping* plm = linkonce_mapping;
1194   for (int i = 0; i < linkonce_mapping_count; ++i, ++plm)
1195     {
1196       if (strncmp(s, plm->from, plm->fromlen) == 0 && s[plm->fromlen] == '.')
1197         {
1198           *plen = plm->tolen;
1199           return plm->to;
1200         }
1201     }
1202   return name;
1203 }
1204
1205 // Choose the output section name to use given an input section name.
1206 // Set *PLEN to the length of the name.  *PLEN is initialized to the
1207 // length of NAME.
1208
1209 const char*
1210 Layout::output_section_name(const char* name, size_t* plen)
1211 {
1212   if (Layout::is_linkonce(name))
1213     {
1214       // .gnu.linkonce sections are laid out as though they were named
1215       // for the sections are placed into.
1216       return Layout::linkonce_output_name(name, plen);
1217     }
1218
1219   // If the section name has no '.', or only an initial '.', we use
1220   // the name unchanged (i.e., ".text" is unchanged).
1221
1222   // Otherwise, if the section name does not include ".rel", we drop
1223   // the last '.'  and everything that follows (i.e., ".text.XXX"
1224   // becomes ".text").
1225
1226   // Otherwise, if the section name has zero or one '.' after the
1227   // ".rel", we use the name unchanged (i.e., ".rel.text" is
1228   // unchanged).
1229
1230   // Otherwise, we drop the last '.' and everything that follows
1231   // (i.e., ".rel.text.XXX" becomes ".rel.text").
1232
1233   const char* s = name;
1234   if (*s == '.')
1235     ++s;
1236   const char* sdot = strchr(s, '.');
1237   if (sdot == NULL)
1238     return name;
1239
1240   const char* srel = strstr(s, ".rel");
1241   if (srel == NULL)
1242     {
1243       *plen = sdot - name;
1244       return name;
1245     }
1246
1247   sdot = strchr(srel + 1, '.');
1248   if (sdot == NULL)
1249     return name;
1250   sdot = strchr(sdot + 1, '.');
1251   if (sdot == NULL)
1252     return name;
1253
1254   *plen = sdot - name;
1255   return name;
1256 }
1257
1258 // Record the signature of a comdat section, and return whether to
1259 // include it in the link.  If GROUP is true, this is a regular
1260 // section group.  If GROUP is false, this is a group signature
1261 // derived from the name of a linkonce section.  We want linkonce
1262 // signatures and group signatures to block each other, but we don't
1263 // want a linkonce signature to block another linkonce signature.
1264
1265 bool
1266 Layout::add_comdat(const char* signature, bool group)
1267 {
1268   std::string sig(signature);
1269   std::pair<Signatures::iterator, bool> ins(
1270     this->signatures_.insert(std::make_pair(sig, group)));
1271
1272   if (ins.second)
1273     {
1274       // This is the first time we've seen this signature.
1275       return true;
1276     }
1277
1278   if (ins.first->second)
1279     {
1280       // We've already seen a real section group with this signature.
1281       return false;
1282     }
1283   else if (group)
1284     {
1285       // This is a real section group, and we've already seen a
1286       // linkonce section with tihs signature.  Record that we've seen
1287       // a section group, and don't include this section group.
1288       ins.first->second = true;
1289       return false;
1290     }
1291   else
1292     {
1293       // We've already seen a linkonce section and this is a linkonce
1294       // section.  These don't block each other--this may be the same
1295       // symbol name with different section types.
1296       return true;
1297     }
1298 }
1299
1300 // Write out data not associated with a section or the symbol table.
1301
1302 void
1303 Layout::write_data(const Symbol_table* symtab, const Target* target,
1304                    Output_file* of) const
1305 {
1306   const Output_section* symtab_section = this->symtab_section_;
1307   for (Section_list::const_iterator p = this->section_list_.begin();
1308        p != this->section_list_.end();
1309        ++p)
1310     {
1311       if ((*p)->needs_symtab_index())
1312         {
1313           gold_assert(symtab_section != NULL);
1314           unsigned int index = (*p)->symtab_index();
1315           gold_assert(index > 0 && index != -1U);
1316           off_t off = (symtab_section->offset()
1317                        + index * symtab_section->entsize());
1318           symtab->write_section_symbol(target, *p, of, off);
1319         }
1320     }
1321
1322   const Output_section* dynsym_section = this->dynsym_section_;
1323   for (Section_list::const_iterator p = this->section_list_.begin();
1324        p != this->section_list_.end();
1325        ++p)
1326     {
1327       if ((*p)->needs_dynsym_index())
1328         {
1329           gold_assert(dynsym_section != NULL);
1330           unsigned int index = (*p)->dynsym_index();
1331           gold_assert(index > 0 && index != -1U);
1332           off_t off = (dynsym_section->offset()
1333                        + index * dynsym_section->entsize());
1334           symtab->write_section_symbol(target, *p, of, off);
1335         }
1336     }
1337
1338   // Write out the Output_sections.  Most won't have anything to
1339   // write, since most of the data will come from input sections which
1340   // are handled elsewhere.  But some Output_sections do have
1341   // Output_data.
1342   for (Section_list::const_iterator p = this->section_list_.begin();
1343        p != this->section_list_.end();
1344        ++p)
1345     (*p)->write(of);
1346
1347   // Write out the Output_data which are not in an Output_section.
1348   for (Data_list::const_iterator p = this->special_output_list_.begin();
1349        p != this->special_output_list_.end();
1350        ++p)
1351     (*p)->write(of);
1352 }
1353
1354 // Write_data_task methods.
1355
1356 // We can always run this task.
1357
1358 Task::Is_runnable_type
1359 Write_data_task::is_runnable(Workqueue*)
1360 {
1361   return IS_RUNNABLE;
1362 }
1363
1364 // We need to unlock FINAL_BLOCKER when finished.
1365
1366 Task_locker*
1367 Write_data_task::locks(Workqueue* workqueue)
1368 {
1369   return new Task_locker_block(*this->final_blocker_, workqueue);
1370 }
1371
1372 // Run the task--write out the data.
1373
1374 void
1375 Write_data_task::run(Workqueue*)
1376 {
1377   this->layout_->write_data(this->symtab_, this->target_, this->of_);
1378 }
1379
1380 // Write_symbols_task methods.
1381
1382 // We can always run this task.
1383
1384 Task::Is_runnable_type
1385 Write_symbols_task::is_runnable(Workqueue*)
1386 {
1387   return IS_RUNNABLE;
1388 }
1389
1390 // We need to unlock FINAL_BLOCKER when finished.
1391
1392 Task_locker*
1393 Write_symbols_task::locks(Workqueue* workqueue)
1394 {
1395   return new Task_locker_block(*this->final_blocker_, workqueue);
1396 }
1397
1398 // Run the task--write out the symbols.
1399
1400 void
1401 Write_symbols_task::run(Workqueue*)
1402 {
1403   this->symtab_->write_globals(this->target_, this->sympool_, this->dynpool_,
1404                                this->of_);
1405 }
1406
1407 // Close_task_runner methods.
1408
1409 // Run the task--close the file.
1410
1411 void
1412 Close_task_runner::run(Workqueue*)
1413 {
1414   this->of_->close();
1415 }
1416
1417 // Instantiate the templates we need.  We could use the configure
1418 // script to restrict this to only the ones for implemented targets.
1419
1420 template
1421 Output_section*
1422 Layout::layout<32, false>(Relobj* object, unsigned int shndx, const char* name,
1423                           const elfcpp::Shdr<32, false>& shdr, off_t*);
1424
1425 template
1426 Output_section*
1427 Layout::layout<32, true>(Relobj* object, unsigned int shndx, const char* name,
1428                          const elfcpp::Shdr<32, true>& shdr, off_t*);
1429
1430 template
1431 Output_section*
1432 Layout::layout<64, false>(Relobj* object, unsigned int shndx, const char* name,
1433                           const elfcpp::Shdr<64, false>& shdr, off_t*);
1434
1435 template
1436 Output_section*
1437 Layout::layout<64, true>(Relobj* object, unsigned int shndx, const char* name,
1438                          const elfcpp::Shdr<64, true>& shdr, off_t*);
1439
1440
1441 } // End namespace gold.