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               | elfcpp::SHF_MERGE
 138               | elfcpp::SHF_STRINGS);
 139
 140   const Key key(name_key, std::make_pair(type, flags));
 141   const std::pair<Key, Output_section*> v(key, NULL);
 142   std::pair<Section_name_map::iterator, bool> ins(
 143     this->section_name_map_.insert(v));
 144
 145   if (!ins.second)
 146     return ins.first->second;
 147   else
 148     {
 149       // This is the first time we've seen this name/type/flags
 150       // combination.
 151       Output_section* os = this->make_output_section(name, type, flags);
 152       ins.first->second = os;
 153       return os;
 154     }
 155 }
 156
 157 // Return the output section to use for input section SHNDX, with name
 158 // NAME, with header HEADER, from object OBJECT.  Set *OFF to the
 159 // offset of this input section without the output section.
 160
 161 template<int size, bool big_endian>
 162 Output_section*
 163 Layout::layout(Relobj* object, unsigned int shndx, const char* name,
 164                const elfcpp::Shdr<size, big_endian>& shdr, off_t* off)
 165 {
 166   if (!this->include_section(object, name, shdr))
 167     return NULL;
 168
 169   // If we are not doing a relocateable link, choose the name to use
 170   // for the output section.
 171   size_t len = strlen(name);
 172   if (!this->options_.is_relocatable())
 173     name = Layout::output_section_name(name, &len);
 174
 175   // FIXME: Handle SHF_OS_NONCONFORMING here.
 176
 177   // Canonicalize the section name.
 178   Stringpool::Key name_key;
 179   name = this->namepool_.add(name, len, &name_key);
 180
 181   // Find the output section.  The output section is selected based on
 182   // the section name, type, and flags.
 183   Output_section* os = this->get_output_section(name, name_key,
 184                                                 shdr.get_sh_type(),
 185                                                 shdr.get_sh_flags());
 186
 187   // FIXME: Handle SHF_LINK_ORDER somewhere.
 188
 189   *off = os->add_input_section(object, shndx, name, shdr);
 190
 191   return os;
 192 }
 193
 194 // Add POSD to an output section using NAME, TYPE, and FLAGS.
 195
 196 void
 197 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
 198                                 elfcpp::Elf_Xword flags,
 199                                 Output_section_data* posd)
 200 {
 201   // Canonicalize the name.
 202   Stringpool::Key name_key;
 203   name = this->namepool_.add(name, &name_key);
 204
 205   Output_section* os = this->get_output_section(name, name_key, type, flags);
 206   os->add_output_section_data(posd);
 207 }
 208
 209 // Map section flags to segment flags.
 210
 211 elfcpp::Elf_Word
 212 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
 213 {
 214   elfcpp::Elf_Word ret = elfcpp::PF_R;
 215   if ((flags & elfcpp::SHF_WRITE) != 0)
 216     ret |= elfcpp::PF_W;
 217   if ((flags & elfcpp::SHF_EXECINSTR) != 0)
 218     ret |= elfcpp::PF_X;
 219   return ret;
 220 }
 221
 222 // Make a new Output_section, and attach it to segments as
 223 // appropriate.
 224
 225 Output_section*
 226 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
 227                             elfcpp::Elf_Xword flags)
 228 {
 229   Output_section* os = new Output_section(name, type, flags);
 230   this->section_list_.push_back(os);
 231
 232   if ((flags & elfcpp::SHF_ALLOC) == 0)
 233     this->unattached_section_list_.push_back(os);
 234   else
 235     {
 236       // This output section goes into a PT_LOAD segment.
 237
 238       elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
 239
 240       // The only thing we really care about for PT_LOAD segments is
 241       // whether or not they are writable, so that is how we search
 242       // for them.  People who need segments sorted on some other
 243       // basis will have to wait until we implement a mechanism for
 244       // them to describe the segments they want.
 245
 246       Segment_list::const_iterator p;
 247       for (p = this->segment_list_.begin();
 248            p != this->segment_list_.end();
 249            ++p)
 250         {
 251           if ((*p)->type() == elfcpp::PT_LOAD
 252               && ((*p)->flags() & elfcpp::PF_W) == (seg_flags & elfcpp::PF_W))
 253             {
 254               (*p)->add_output_section(os, seg_flags);
 255               break;
 256             }
 257         }
 258
 259       if (p == this->segment_list_.end())
 260         {
 261           Output_segment* oseg = new Output_segment(elfcpp::PT_LOAD,
 262                                                     seg_flags);
 263           this->segment_list_.push_back(oseg);
 264           oseg->add_output_section(os, seg_flags);
 265         }
 266
 267       // If we see a loadable SHT_NOTE section, we create a PT_NOTE
 268       // segment.
 269       if (type == elfcpp::SHT_NOTE)
 270         {
 271           // See if we already have an equivalent PT_NOTE segment.
 272           for (p = this->segment_list_.begin();
 273                p != segment_list_.end();
 274                ++p)
 275             {
 276               if ((*p)->type() == elfcpp::PT_NOTE
 277                   && (((*p)->flags() & elfcpp::PF_W)
 278                       == (seg_flags & elfcpp::PF_W)))
 279                 {
 280                   (*p)->add_output_section(os, seg_flags);
 281                   break;
 282                 }
 283             }
 284
 285           if (p == this->segment_list_.end())
 286             {
 287               Output_segment* oseg = new Output_segment(elfcpp::PT_NOTE,
 288                                                         seg_flags);
 289               this->segment_list_.push_back(oseg);
 290               oseg->add_output_section(os, seg_flags);
 291             }
 292         }
 293
 294       // If we see a loadable SHF_TLS section, we create a PT_TLS
 295       // segment.  There can only be one such segment.
 296       if ((flags & elfcpp::SHF_TLS) != 0)
 297         {
 298           if (this->tls_segment_ == NULL)
 299             {
 300               this->tls_segment_ = new Output_segment(elfcpp::PT_TLS,
 301                                                       seg_flags);
 302               this->segment_list_.push_back(this->tls_segment_);
 303             }
 304           this->tls_segment_->add_output_section(os, seg_flags);
 305         }
 306     }
 307
 308   return os;
 309 }
 310
 311 // Create the dynamic sections which are needed before we read the
 312 // relocs.
 313
 314 void
 315 Layout::create_initial_dynamic_sections(const Input_objects* input_objects,
 316                                         Symbol_table* symtab)
 317 {
 318   if (!input_objects->any_dynamic())
 319     return;
 320
 321   const char* dynamic_name = this->namepool_.add(".dynamic", NULL);
 322   this->dynamic_section_ = this->make_output_section(dynamic_name,
 323                                                      elfcpp::SHT_DYNAMIC,
 324                                                      (elfcpp::SHF_ALLOC
 325                                                       | elfcpp::SHF_WRITE));
 326
 327   symtab->define_in_output_data(input_objects->target(), "_DYNAMIC", NULL,
 328                                 this->dynamic_section_, 0, 0,
 329                                 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
 330                                 elfcpp::STV_HIDDEN, 0, false, false);
 331
 332   this->dynamic_data_ =  new Output_data_dynamic(input_objects->target(),
 333                                                  &this->dynpool_);
 334
 335   this->dynamic_section_->add_output_section_data(this->dynamic_data_);
 336 }
 337
 338 // Find the first read-only PT_LOAD segment, creating one if
 339 // necessary.
 340
 341 Output_segment*
 342 Layout::find_first_load_seg()
 343 {
 344   for (Segment_list::const_iterator p = this->segment_list_.begin();
 345        p != this->segment_list_.end();
 346        ++p)
 347     {
 348       if ((*p)->type() == elfcpp::PT_LOAD
 349           && ((*p)->flags() & elfcpp::PF_R) != 0
 350           && ((*p)->flags() & elfcpp::PF_W) == 0)
 351         return *p;
 352     }
 353
 354   Output_segment* load_seg = new Output_segment(elfcpp::PT_LOAD, elfcpp::PF_R);
 355   this->segment_list_.push_back(load_seg);
 356   return load_seg;
 357 }
 358
 359 // Finalize the layout.  When this is called, we have created all the
 360 // output sections and all the output segments which are based on
 361 // input sections.  We have several things to do, and we have to do
 362 // them in the right order, so that we get the right results correctly
 363 // and efficiently.
 364
 365 // 1) Finalize the list of output segments and create the segment
 366 // table header.
 367
 368 // 2) Finalize the dynamic symbol table and associated sections.
 369
 370 // 3) Determine the final file offset of all the output segments.
 371
 372 // 4) Determine the final file offset of all the SHF_ALLOC output
 373 // sections.
 374
 375 // 5) Create the symbol table sections and the section name table
 376 // section.
 377
 378 // 6) Finalize the symbol table: set symbol values to their final
 379 // value and make a final determination of which symbols are going
 380 // into the output symbol table.
 381
 382 // 7) Create the section table header.
 383
 384 // 8) Determine the final file offset of all the output sections which
 385 // are not SHF_ALLOC, including the section table header.
 386
 387 // 9) Finalize the ELF file header.
 388
 389 // This function returns the size of the output file.
 390
 391 off_t
 392 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab)
 393 {
 394   Target* const target = input_objects->target();
 395   const int size = target->get_size();
 396
 397   target->finalize_sections(&this->options_, this);
 398
 399   Output_segment* phdr_seg = NULL;
 400   if (input_objects->any_dynamic())
 401     {
 402       // There was a dynamic object in the link.  We need to create
 403       // some information for the dynamic linker.
 404
 405       // Create the PT_PHDR segment which will hold the program
 406       // headers.
 407       phdr_seg = new Output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
 408       this->segment_list_.push_back(phdr_seg);
 409
 410       // Create the dynamic symbol table, including the hash table.
 411       Output_section* dynstr;
 412       std::vector<Symbol*> dynamic_symbols;
 413       unsigned int local_dynamic_count;
 414       Versions versions;
 415       this->create_dynamic_symtab(target, symtab, &dynstr,
 416                                   &local_dynamic_count, &dynamic_symbols,
 417                                   &versions);
 418
 419       // Create the .interp section to hold the name of the
 420       // interpreter, and put it in a PT_INTERP segment.
 421       this->create_interp(target);
 422
 423       // Finish the .dynamic section to hold the dynamic data, and put
 424       // it in a PT_DYNAMIC segment.
 425       this->finish_dynamic_section(input_objects, symtab);
 426
 427       // We should have added everything we need to the dynamic string
 428       // table.
 429       this->dynpool_.set_string_offsets();
 430
 431       // Create the version sections.  We can't do this until the
 432       // dynamic string table is complete.
 433       this->create_version_sections(target, &versions, local_dynamic_count,
 434                                     dynamic_symbols, dynstr);
 435     }
 436
 437   // FIXME: Handle PT_GNU_STACK.
 438
 439   Output_segment* load_seg = this->find_first_load_seg();
 440
 441   // Lay out the segment headers.
 442   bool big_endian = target->is_big_endian();
 443   Output_segment_headers* segment_headers;
 444   segment_headers = new Output_segment_headers(size, big_endian,
 445                                                this->segment_list_);
 446   load_seg->add_initial_output_data(segment_headers);
 447   this->special_output_list_.push_back(segment_headers);
 448   if (phdr_seg != NULL)
 449     phdr_seg->add_initial_output_data(segment_headers);
 450
 451   // Lay out the file header.
 452   Output_file_header* file_header;
 453   file_header = new Output_file_header(size,
 454                                        big_endian,
 455                                        this->options_,
 456                                        target,
 457                                        symtab,
 458                                        segment_headers);
 459   load_seg->add_initial_output_data(file_header);
 460   this->special_output_list_.push_back(file_header);
 461
 462   // We set the output section indexes in set_segment_offsets and
 463   // set_section_offsets.
 464   unsigned int shndx = 1;
 465
 466   // Set the file offsets of all the segments, and all the sections
 467   // they contain.
 468   off_t off = this->set_segment_offsets(target, load_seg, &shndx);
 469
 470   // Create the symbol table sections.
 471   this->create_symtab_sections(size, input_objects, symtab, &off);
 472
 473   // Create the .shstrtab section.
 474   Output_section* shstrtab_section = this->create_shstrtab();
 475
 476   // Set the file offsets of all the sections not associated with
 477   // segments.
 478   off = this->set_section_offsets(off, &shndx);
 479
 480   // Create the section table header.
 481   Output_section_headers* oshdrs = this->create_shdrs(size, big_endian, &off);
 482
 483   file_header->set_section_info(oshdrs, shstrtab_section);
 484
 485   // Now we know exactly where everything goes in the output file.
 486   Output_data::layout_complete();
 487
 488   return off;
 489 }
 490
 491 // Return whether SEG1 should be before SEG2 in the output file.  This
 492 // is based entirely on the segment type and flags.  When this is
 493 // called the segment addresses has normally not yet been set.
 494
 495 bool
 496 Layout::segment_precedes(const Output_segment* seg1,
 497                          const Output_segment* seg2)
 498 {
 499   elfcpp::Elf_Word type1 = seg1->type();
 500   elfcpp::Elf_Word type2 = seg2->type();
 501
 502   // The single PT_PHDR segment is required to precede any loadable
 503   // segment.  We simply make it always first.
 504   if (type1 == elfcpp::PT_PHDR)
 505     {
 506       gold_assert(type2 != elfcpp::PT_PHDR);
 507       return true;
 508     }
 509   if (type2 == elfcpp::PT_PHDR)
 510     return false;
 511
 512   // The single PT_INTERP segment is required to precede any loadable
 513   // segment.  We simply make it always second.
 514   if (type1 == elfcpp::PT_INTERP)
 515     {
 516       gold_assert(type2 != elfcpp::PT_INTERP);
 517       return true;
 518     }
 519   if (type2 == elfcpp::PT_INTERP)
 520     return false;
 521
 522   // We then put PT_LOAD segments before any other segments.
 523   if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
 524     return true;
 525   if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
 526     return false;
 527
 528   // We put the PT_TLS segment last, because that is where the dynamic
 529   // linker expects to find it (this is just for efficiency; other
 530   // positions would also work correctly).
 531   if (type1 == elfcpp::PT_TLS && type2 != elfcpp::PT_TLS)
 532     return false;
 533   if (type2 == elfcpp::PT_TLS && type1 != elfcpp::PT_TLS)
 534     return true;
 535
 536   const elfcpp::Elf_Word flags1 = seg1->flags();
 537   const elfcpp::Elf_Word flags2 = seg2->flags();
 538
 539   // The order of non-PT_LOAD segments is unimportant.  We simply sort
 540   // by the numeric segment type and flags values.  There should not
 541   // be more than one segment with the same type and flags.
 542   if (type1 != elfcpp::PT_LOAD)
 543     {
 544       if (type1 != type2)
 545         return type1 < type2;
 546       gold_assert(flags1 != flags2);
 547       return flags1 < flags2;
 548     }
 549
 550   // We sort PT_LOAD segments based on the flags.  Readonly segments
 551   // come before writable segments.  Then executable segments come
 552   // before non-executable segments.  Then the unlikely case of a
 553   // non-readable segment comes before the normal case of a readable
 554   // segment.  If there are multiple segments with the same type and
 555   // flags, we require that the address be set, and we sort by
 556   // virtual address and then physical address.
 557   if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
 558     return (flags1 & elfcpp::PF_W) == 0;
 559   if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
 560     return (flags1 & elfcpp::PF_X) != 0;
 561   if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
 562     return (flags1 & elfcpp::PF_R) == 0;
 563
 564   uint64_t vaddr1 = seg1->vaddr();
 565   uint64_t vaddr2 = seg2->vaddr();
 566   if (vaddr1 != vaddr2)
 567     return vaddr1 < vaddr2;
 568
 569   uint64_t paddr1 = seg1->paddr();
 570   uint64_t paddr2 = seg2->paddr();
 571   gold_assert(paddr1 != paddr2);
 572   return paddr1 < paddr2;
 573 }
 574
 575 // Set the file offsets of all the segments, and all the sections they
 576 // contain.  They have all been created.  LOAD_SEG must be be laid out
 577 // first.  Return the offset of the data to follow.
 578
 579 off_t
 580 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
 581                             unsigned int *pshndx)
 582 {
 583   // Sort them into the final order.
 584   std::sort(this->segment_list_.begin(), this->segment_list_.end(),
 585             Layout::Compare_segments());
 586
 587   // Find the PT_LOAD segments, and set their addresses and offsets
 588   // and their section's addresses and offsets.
 589   uint64_t addr = target->text_segment_address();
 590   off_t off = 0;
 591   bool was_readonly = false;
 592   for (Segment_list::iterator p = this->segment_list_.begin();
 593        p != this->segment_list_.end();
 594        ++p)
 595     {
 596       if ((*p)->type() == elfcpp::PT_LOAD)
 597         {
 598           if (load_seg != NULL && load_seg != *p)
 599             gold_unreachable();
 600           load_seg = NULL;
 601
 602           // If the last segment was readonly, and this one is not,
 603           // then skip the address forward one page, maintaining the
 604           // same position within the page.  This lets us store both
 605           // segments overlapping on a single page in the file, but
 606           // the loader will put them on different pages in memory.
 607
 608           uint64_t orig_addr = addr;
 609           uint64_t orig_off = off;
 610
 611           uint64_t aligned_addr = addr;
 612           uint64_t abi_pagesize = target->abi_pagesize();
 613           if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0)
 614             {
 615               uint64_t align = (*p)->addralign();
 616
 617               addr = align_address(addr, align);
 618               aligned_addr = addr;
 619               if ((addr & (abi_pagesize - 1)) != 0)
 620                 addr = addr + abi_pagesize;
 621             }
 622
 623           unsigned int shndx_hold = *pshndx;
 624           off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
 625           uint64_t new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
 626
 627           // Now that we know the size of this segment, we may be able
 628           // to save a page in memory, at the cost of wasting some
 629           // file space, by instead aligning to the start of a new
 630           // page.  Here we use the real machine page size rather than
 631           // the ABI mandated page size.
 632
 633           if (aligned_addr != addr)
 634             {
 635               uint64_t common_pagesize = target->common_pagesize();
 636               uint64_t first_off = (common_pagesize
 637                                     - (aligned_addr
 638                                        & (common_pagesize - 1)));
 639               uint64_t last_off = new_addr & (common_pagesize - 1);
 640               if (first_off > 0
 641                   && last_off > 0
 642                   && ((aligned_addr & ~ (common_pagesize - 1))
 643                       != (new_addr & ~ (common_pagesize - 1)))
 644                   && first_off + last_off <= common_pagesize)
 645                 {
 646                   *pshndx = shndx_hold;
 647                   addr = align_address(aligned_addr, common_pagesize);
 648                   off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
 649                   new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
 650                 }
 651             }
 652
 653           addr = new_addr;
 654
 655           if (((*p)->flags() & elfcpp::PF_W) == 0)
 656             was_readonly = true;
 657         }
 658     }
 659
 660   // Handle the non-PT_LOAD segments, setting their offsets from their
 661   // section's offsets.
 662   for (Segment_list::iterator p = this->segment_list_.begin();
 663        p != this->segment_list_.end();
 664        ++p)
 665     {
 666       if ((*p)->type() != elfcpp::PT_LOAD)
 667         (*p)->set_offset();
 668     }
 669
 670   return off;
 671 }
 672
 673 // Set the file offset of all the sections not associated with a
 674 // segment.
 675
 676 off_t
 677 Layout::set_section_offsets(off_t off, unsigned int* pshndx)
 678 {
 679   for (Section_list::iterator p = this->unattached_section_list_.begin();
 680        p != this->unattached_section_list_.end();
 681        ++p)
 682     {
 683       (*p)->set_out_shndx(*pshndx);
 684       ++*pshndx;
 685       if ((*p)->offset() != -1)
 686         continue;
 687       off = align_address(off, (*p)->addralign());
 688       (*p)->set_address(0, off);
 689       off += (*p)->data_size();
 690     }
 691   return off;
 692 }
 693
 694 // Create the symbol table sections.  Here we also set the final
 695 // values of the symbols.  At this point all the loadable sections are
 696 // fully laid out.
 697
 698 void
 699 Layout::create_symtab_sections(int size, const Input_objects* input_objects,
 700                                Symbol_table* symtab,
 701                                off_t* poff)
 702 {
 703   int symsize;
 704   unsigned int align;
 705   if (size == 32)
 706     {
 707       symsize = elfcpp::Elf_sizes<32>::sym_size;
 708       align = 4;
 709     }
 710   else if (size == 64)
 711     {
 712       symsize = elfcpp::Elf_sizes<64>::sym_size;
 713       align = 8;
 714     }
 715   else
 716     gold_unreachable();
 717
 718   off_t off = *poff;
 719   off = align_address(off, align);
 720   off_t startoff = off;
 721
 722   // Save space for the dummy symbol at the start of the section.  We
 723   // never bother to write this out--it will just be left as zero.
 724   off += symsize;
 725   unsigned int local_symbol_index = 1;
 726
 727   // Add STT_SECTION symbols for each Output section which needs one.
 728   for (Section_list::iterator p = this->section_list_.begin();
 729        p != this->section_list_.end();
 730        ++p)
 731     {
 732       if (!(*p)->needs_symtab_index())
 733         (*p)->set_symtab_index(-1U);
 734       else
 735         {
 736           (*p)->set_symtab_index(local_symbol_index);
 737           ++local_symbol_index;
 738           off += symsize;
 739         }
 740     }
 741
 742   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
 743        p != input_objects->relobj_end();
 744        ++p)
 745     {
 746       Task_lock_obj<Object> tlo(**p);
 747       unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
 748                                                         off,
 749                                                         &this->sympool_);
 750       off += (index - local_symbol_index) * symsize;
 751       local_symbol_index = index;
 752     }
 753
 754   unsigned int local_symcount = local_symbol_index;
 755   gold_assert(local_symcount * symsize == off - startoff);
 756
 757   off_t dynoff;
 758   size_t dyn_global_index;
 759   size_t dyncount;
 760   if (this->dynsym_section_ == NULL)
 761     {
 762       dynoff = 0;
 763       dyn_global_index = 0;
 764       dyncount = 0;
 765     }
 766   else
 767     {
 768       dyn_global_index = this->dynsym_section_->info();
 769       off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
 770       dynoff = this->dynsym_section_->offset() + locsize;
 771       dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
 772       gold_assert(dyncount * symsize
 773                   == this->dynsym_section_->data_size() - locsize);
 774     }
 775
 776   off = symtab->finalize(local_symcount, off, dynoff, dyn_global_index,
 777                          dyncount, &this->sympool_);
 778
 779   this->sympool_.set_string_offsets();
 780
 781   const char* symtab_name = this->namepool_.add(".symtab", NULL);
 782   Output_section* osymtab = this->make_output_section(symtab_name,
 783                                                       elfcpp::SHT_SYMTAB,
 784                                                       0);
 785   this->symtab_section_ = osymtab;
 786
 787   Output_section_data* pos = new Output_data_space(off - startoff,
 788                                                    align);
 789   osymtab->add_output_section_data(pos);
 790
 791   const char* strtab_name = this->namepool_.add(".strtab", NULL);
 792   Output_section* ostrtab = this->make_output_section(strtab_name,
 793                                                       elfcpp::SHT_STRTAB,
 794                                                       0);
 795
 796   Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
 797   ostrtab->add_output_section_data(pstr);
 798
 799   osymtab->set_address(0, startoff);
 800   osymtab->set_link_section(ostrtab);
 801   osymtab->set_info(local_symcount);
 802   osymtab->set_entsize(symsize);
 803
 804   *poff = off;
 805 }
 806
 807 // Create the .shstrtab section, which holds the names of the
 808 // sections.  At the time this is called, we have created all the
 809 // output sections except .shstrtab itself.
 810
 811 Output_section*
 812 Layout::create_shstrtab()
 813 {
 814   // FIXME: We don't need to create a .shstrtab section if we are
 815   // stripping everything.
 816
 817   const char* name = this->namepool_.add(".shstrtab", NULL);
 818
 819   this->namepool_.set_string_offsets();
 820
 821   Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0);
 822
 823   Output_section_data* posd = new Output_data_strtab(&this->namepool_);
 824   os->add_output_section_data(posd);
 825
 826   return os;
 827 }
 828
 829 // Create the section headers.  SIZE is 32 or 64.  OFF is the file
 830 // offset.
 831
 832 Output_section_headers*
 833 Layout::create_shdrs(int size, bool big_endian, off_t* poff)
 834 {
 835   Output_section_headers* oshdrs;
 836   oshdrs = new Output_section_headers(size, big_endian, this,
 837                                       &this->segment_list_,
 838                                       &this->unattached_section_list_,
 839                                       &this->namepool_);
 840   off_t off = align_address(*poff, oshdrs->addralign());
 841   oshdrs->set_address(0, off);
 842   off += oshdrs->data_size();
 843   *poff = off;
 844   this->special_output_list_.push_back(oshdrs);
 845   return oshdrs;
 846 }
 847
 848 // Create the dynamic symbol table.
 849
 850 void
 851 Layout::create_dynamic_symtab(const Target* target, Symbol_table* symtab,
 852                               Output_section **pdynstr,
 853                               unsigned int* plocal_dynamic_count,
 854                               std::vector<Symbol*>* pdynamic_symbols,
 855                               Versions* pversions)
 856 {
 857   // Count all the symbols in the dynamic symbol table, and set the
 858   // dynamic symbol indexes.
 859
 860   // Skip symbol 0, which is always all zeroes.
 861   unsigned int index = 1;
 862
 863   // Add STT_SECTION symbols for each Output section which needs one.
 864   for (Section_list::iterator p = this->section_list_.begin();
 865        p != this->section_list_.end();
 866        ++p)
 867     {
 868       if (!(*p)->needs_dynsym_index())
 869         (*p)->set_dynsym_index(-1U);
 870       else
 871         {
 872           (*p)->set_dynsym_index(index);
 873           ++index;
 874         }
 875     }
 876
 877   // FIXME: Some targets apparently require local symbols in the
 878   // dynamic symbol table.  Here is where we will have to count them,
 879   // and set the dynamic symbol indexes, and add the names to
 880   // this->dynpool_.
 881
 882   unsigned int local_symcount = index;
 883   *plocal_dynamic_count = local_symcount;
 884
 885   // FIXME: We have to tell set_dynsym_indexes whether the
 886   // -E/--export-dynamic option was used.
 887   index = symtab->set_dynsym_indexes(&this->options_, target, index,
 888                                      pdynamic_symbols, &this->dynpool_,
 889                                      pversions);
 890
 891   int symsize;
 892   unsigned int align;
 893   const int size = target->get_size();
 894   if (size == 32)
 895     {
 896       symsize = elfcpp::Elf_sizes<32>::sym_size;
 897       align = 4;
 898     }
 899   else if (size == 64)
 900     {
 901       symsize = elfcpp::Elf_sizes<64>::sym_size;
 902       align = 8;
 903     }
 904   else
 905     gold_unreachable();
 906
 907   // Create the dynamic symbol table section.
 908
 909   const char* dynsym_name = this->namepool_.add(".dynsym", NULL);
 910   Output_section* dynsym = this->make_output_section(dynsym_name,
 911                                                      elfcpp::SHT_DYNSYM,
 912                                                      elfcpp::SHF_ALLOC);
 913
 914   Output_section_data* odata = new Output_data_space(index * symsize,
 915                                                      align);
 916   dynsym->add_output_section_data(odata);
 917
 918   dynsym->set_info(local_symcount);
 919   dynsym->set_entsize(symsize);
 920   dynsym->set_addralign(align);
 921
 922   this->dynsym_section_ = dynsym;
 923
 924   Output_data_dynamic* const odyn = this->dynamic_data_;
 925   odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
 926   odyn->add_constant(elfcpp::DT_SYMENT, symsize);
 927
 928   // Create the dynamic string table section.
 929
 930   const char* dynstr_name = this->namepool_.add(".dynstr", NULL);
 931   Output_section* dynstr = this->make_output_section(dynstr_name,
 932                                                      elfcpp::SHT_STRTAB,
 933                                                      elfcpp::SHF_ALLOC);
 934
 935   Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
 936   dynstr->add_output_section_data(strdata);
 937
 938   dynsym->set_link_section(dynstr);
 939   this->dynamic_section_->set_link_section(dynstr);
 940
 941   odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
 942   odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
 943
 944   *pdynstr = dynstr;
 945
 946   // Create the hash tables.
 947
 948   // FIXME: We need an option to create a GNU hash table.
 949
 950   unsigned char* phash;
 951   unsigned int hashlen;
 952   Dynobj::create_elf_hash_table(target, *pdynamic_symbols, local_symcount,
 953                                 &phash, &hashlen);
 954
 955   const char* hash_name = this->namepool_.add(".hash", NULL);
 956   Output_section* hashsec = this->make_output_section(hash_name,
 957                                                       elfcpp::SHT_HASH,
 958                                                       elfcpp::SHF_ALLOC);
 959
 960   Output_section_data* hashdata = new Output_data_const_buffer(phash,
 961                                                                hashlen,
 962                                                                align);
 963   hashsec->add_output_section_data(hashdata);
 964
 965   hashsec->set_link_section(dynsym);
 966   hashsec->set_entsize(4);
 967
 968   odyn->add_section_address(elfcpp::DT_HASH, hashsec);
 969 }
 970
 971 // Create the version sections.
 972
 973 void
 974 Layout::create_version_sections(const Target* target, const Versions* versions,
 975                                 unsigned int local_symcount,
 976                                 const std::vector<Symbol*>& dynamic_symbols,
 977                                 const Output_section* dynstr)
 978 {
 979   if (!versions->any_defs() && !versions->any_needs())
 980     return;
 981
 982   if (target->get_size() == 32)
 983     {
 984       if (target->is_big_endian())
 985         this->sized_create_version_sections SELECT_SIZE_ENDIAN_NAME(32, true)(
 986             versions, local_symcount, dynamic_symbols, dynstr
 987             SELECT_SIZE_ENDIAN(32, true));
 988       else
 989         this->sized_create_version_sections SELECT_SIZE_ENDIAN_NAME(32, false)(
 990             versions, local_symcount, dynamic_symbols, dynstr
 991             SELECT_SIZE_ENDIAN(32, false));
 992     }
 993   else if (target->get_size() == 64)
 994     {
 995       if (target->is_big_endian())
 996         this->sized_create_version_sections SELECT_SIZE_ENDIAN_NAME(64, true)(
 997             versions, local_symcount, dynamic_symbols, dynstr
 998             SELECT_SIZE_ENDIAN(64, true));
 999       else
1000         this->sized_create_version_sections SELECT_SIZE_ENDIAN_NAME(64, false)(
1001             versions, local_symcount, dynamic_symbols, dynstr
1002             SELECT_SIZE_ENDIAN(64, false));
1003     }
1004   else
1005     gold_unreachable();
1006 }
1007
1008 // Create the version sections, sized version.
1009
1010 template<int size, bool big_endian>
1011 void
1012 Layout::sized_create_version_sections(
1013     const Versions* versions,
1014     unsigned int local_symcount,
1015     const std::vector<Symbol*>& dynamic_symbols,
1016     const Output_section* dynstr
1017     ACCEPT_SIZE_ENDIAN)
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 SELECT_SIZE_ENDIAN_NAME(size, big_endian)(
1027       &this->dynpool_, local_symcount, dynamic_symbols, &vbuf, &vsize
1028       SELECT_SIZE_ENDIAN(size, big_endian));
1029
1030   Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2);
1031
1032   vsec->add_output_section_data(vdata);
1033   vsec->set_entsize(2);
1034   vsec->set_link_section(this->dynsym_section_);
1035
1036   Output_data_dynamic* const odyn = this->dynamic_data_;
1037   odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
1038
1039   if (versions->any_defs())
1040     {
1041       const char* vdname = this->namepool_.add(".gnu.version_d", NULL);
1042       Output_section *vdsec;
1043       vdsec = this->make_output_section(vdname, elfcpp::SHT_GNU_verdef,
1044                                         elfcpp::SHF_ALLOC);
1045
1046       unsigned char* vdbuf;
1047       unsigned int vdsize;
1048       unsigned int vdentries;
1049       versions->def_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)(
1050           &this->dynpool_, &vdbuf, &vdsize, &vdentries
1051           SELECT_SIZE_ENDIAN(size, big_endian));
1052
1053       Output_section_data* vddata = new Output_data_const_buffer(vdbuf,
1054                                                                  vdsize,
1055                                                                  4);
1056
1057       vdsec->add_output_section_data(vddata);
1058       vdsec->set_link_section(dynstr);
1059       vdsec->set_info(vdentries);
1060
1061       odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
1062       odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
1063     }
1064
1065   if (versions->any_needs())
1066     {
1067       const char* vnname = this->namepool_.add(".gnu.version_r", NULL);
1068       Output_section* vnsec;
1069       vnsec = this->make_output_section(vnname, elfcpp::SHT_GNU_verneed,
1070                                         elfcpp::SHF_ALLOC);
1071
1072       unsigned char* vnbuf;
1073       unsigned int vnsize;
1074       unsigned int vnentries;
1075       versions->need_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)
1076         (&this->dynpool_, &vnbuf, &vnsize, &vnentries
1077          SELECT_SIZE_ENDIAN(size, big_endian));
1078
1079       Output_section_data* vndata = new Output_data_const_buffer(vnbuf,
1080                                                                  vnsize,
1081                                                                  4);
1082
1083       vnsec->add_output_section_data(vndata);
1084       vnsec->set_link_section(dynstr);
1085       vnsec->set_info(vnentries);
1086
1087       odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
1088       odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
1089     }
1090 }
1091
1092 // Create the .interp section and PT_INTERP segment.
1093
1094 void
1095 Layout::create_interp(const Target* target)
1096 {
1097   const char* interp = this->options_.dynamic_linker();
1098   if (interp == NULL)
1099     {
1100       interp = target->dynamic_linker();
1101       gold_assert(interp != NULL);
1102     }
1103
1104   size_t len = strlen(interp) + 1;
1105
1106   Output_section_data* odata = new Output_data_const(interp, len, 1);
1107
1108   const char* interp_name = this->namepool_.add(".interp", NULL);
1109   Output_section* osec = this->make_output_section(interp_name,
1110                                                    elfcpp::SHT_PROGBITS,
1111                                                    elfcpp::SHF_ALLOC);
1112   osec->add_output_section_data(odata);
1113
1114   Output_segment* oseg = new Output_segment(elfcpp::PT_INTERP, elfcpp::PF_R);
1115   this->segment_list_.push_back(oseg);
1116   oseg->add_initial_output_section(osec, elfcpp::PF_R);
1117 }
1118
1119 // Finish the .dynamic section and PT_DYNAMIC segment.
1120
1121 void
1122 Layout::finish_dynamic_section(const Input_objects* input_objects,
1123                                const Symbol_table* symtab)
1124 {
1125   Output_segment* oseg = new Output_segment(elfcpp::PT_DYNAMIC,
1126                                             elfcpp::PF_R | elfcpp::PF_W);
1127   this->segment_list_.push_back(oseg);
1128   oseg->add_initial_output_section(this->dynamic_section_,
1129                                    elfcpp::PF_R | elfcpp::PF_W);
1130
1131   Output_data_dynamic* const odyn = this->dynamic_data_;
1132
1133   for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
1134        p != input_objects->dynobj_end();
1135        ++p)
1136     {
1137       // FIXME: Handle --as-needed.
1138       odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
1139     }
1140
1141   // FIXME: Support --init and --fini.
1142   Symbol* sym = symtab->lookup("_init");
1143   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
1144     odyn->add_symbol(elfcpp::DT_INIT, sym);
1145
1146   sym = symtab->lookup("_fini");
1147   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
1148     odyn->add_symbol(elfcpp::DT_FINI, sym);
1149
1150   // FIXME: Support DT_INIT_ARRAY and DT_FINI_ARRAY.
1151
1152   // Add a DT_RPATH entry if needed.
1153   const General_options::Dir_list& rpath(this->options_.rpath());
1154   if (!rpath.empty())
1155     {
1156       std::string rpath_val;
1157       for (General_options::Dir_list::const_iterator p = rpath.begin();
1158            p != rpath.end();
1159            ++p)
1160         {
1161           if (rpath_val.empty())
1162             rpath_val = *p;
1163           else
1164             {
1165               // Eliminate duplicates.
1166               General_options::Dir_list::const_iterator q;
1167               for (q = rpath.begin(); q != p; ++q)
1168                 if (strcmp(*q, *p) == 0)
1169                   break;
1170               if (q == p)
1171                 {
1172                   rpath_val += ':';
1173                   rpath_val += *p;
1174                 }
1175             }
1176         }
1177
1178       odyn->add_string(elfcpp::DT_RPATH, rpath_val);
1179     }
1180 }
1181
1182 // The mapping of .gnu.linkonce section names to real section names.
1183
1184 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
1185 const Layout::Linkonce_mapping Layout::linkonce_mapping[] =
1186 {
1187   MAPPING_INIT("d.rel.ro", ".data.rel.ro"),     // Must be before "d".
1188   MAPPING_INIT("t", ".text"),
1189   MAPPING_INIT("r", ".rodata"),
1190   MAPPING_INIT("d", ".data"),
1191   MAPPING_INIT("b", ".bss"),
1192   MAPPING_INIT("s", ".sdata"),
1193   MAPPING_INIT("sb", ".sbss"),
1194   MAPPING_INIT("s2", ".sdata2"),
1195   MAPPING_INIT("sb2", ".sbss2"),
1196   MAPPING_INIT("wi", ".debug_info"),
1197   MAPPING_INIT("td", ".tdata"),
1198   MAPPING_INIT("tb", ".tbss"),
1199   MAPPING_INIT("lr", ".lrodata"),
1200   MAPPING_INIT("l", ".ldata"),
1201   MAPPING_INIT("lb", ".lbss"),
1202 };
1203 #undef MAPPING_INIT
1204
1205 const int Layout::linkonce_mapping_count =
1206   sizeof(Layout::linkonce_mapping) / sizeof(Layout::linkonce_mapping[0]);
1207
1208 // Return the name of the output section to use for a .gnu.linkonce
1209 // section.  This is based on the default ELF linker script of the old
1210 // GNU linker.  For example, we map a name like ".gnu.linkonce.t.foo"
1211 // to ".text".  Set *PLEN to the length of the name.  *PLEN is
1212 // initialized to the length of NAME.
1213
1214 const char*
1215 Layout::linkonce_output_name(const char* name, size_t *plen)
1216 {
1217   const char* s = name + sizeof(".gnu.linkonce") - 1;
1218   if (*s != '.')
1219     return name;
1220   ++s;
1221   const Linkonce_mapping* plm = linkonce_mapping;
1222   for (int i = 0; i < linkonce_mapping_count; ++i, ++plm)
1223     {
1224       if (strncmp(s, plm->from, plm->fromlen) == 0 && s[plm->fromlen] == '.')
1225         {
1226           *plen = plm->tolen;
1227           return plm->to;
1228         }
1229     }
1230   return name;
1231 }
1232
1233 // Choose the output section name to use given an input section name.
1234 // Set *PLEN to the length of the name.  *PLEN is initialized to the
1235 // length of NAME.
1236
1237 const char*
1238 Layout::output_section_name(const char* name, size_t* plen)
1239 {
1240   if (Layout::is_linkonce(name))
1241     {
1242       // .gnu.linkonce sections are laid out as though they were named
1243       // for the sections are placed into.
1244       return Layout::linkonce_output_name(name, plen);
1245     }
1246
1247   // If the section name has no '.', or only an initial '.', we use
1248   // the name unchanged (i.e., ".text" is unchanged).
1249
1250   // Otherwise, if the section name does not include ".rel", we drop
1251   // the last '.'  and everything that follows (i.e., ".text.XXX"
1252   // becomes ".text").
1253
1254   // Otherwise, if the section name has zero or one '.' after the
1255   // ".rel", we use the name unchanged (i.e., ".rel.text" is
1256   // unchanged).
1257
1258   // Otherwise, we drop the last '.' and everything that follows
1259   // (i.e., ".rel.text.XXX" becomes ".rel.text").
1260
1261   const char* s = name;
1262   if (*s == '.')
1263     ++s;
1264   const char* sdot = strchr(s, '.');
1265   if (sdot == NULL)
1266     return name;
1267
1268   const char* srel = strstr(s, ".rel");
1269   if (srel == NULL)
1270     {
1271       *plen = sdot - name;
1272       return name;
1273     }
1274
1275   sdot = strchr(srel + 1, '.');
1276   if (sdot == NULL)
1277     return name;
1278   sdot = strchr(sdot + 1, '.');
1279   if (sdot == NULL)
1280     return name;
1281
1282   *plen = sdot - name;
1283   return name;
1284 }
1285
1286 // Record the signature of a comdat section, and return whether to
1287 // include it in the link.  If GROUP is true, this is a regular
1288 // section group.  If GROUP is false, this is a group signature
1289 // derived from the name of a linkonce section.  We want linkonce
1290 // signatures and group signatures to block each other, but we don't
1291 // want a linkonce signature to block another linkonce signature.
1292
1293 bool
1294 Layout::add_comdat(const char* signature, bool group)
1295 {
1296   std::string sig(signature);
1297   std::pair<Signatures::iterator, bool> ins(
1298     this->signatures_.insert(std::make_pair(sig, group)));
1299
1300   if (ins.second)
1301     {
1302       // This is the first time we've seen this signature.
1303       return true;
1304     }
1305
1306   if (ins.first->second)
1307     {
1308       // We've already seen a real section group with this signature.
1309       return false;
1310     }
1311   else if (group)
1312     {
1313       // This is a real section group, and we've already seen a
1314       // linkonce section with tihs signature.  Record that we've seen
1315       // a section group, and don't include this section group.
1316       ins.first->second = true;
1317       return false;
1318     }
1319   else
1320     {
1321       // We've already seen a linkonce section and this is a linkonce
1322       // section.  These don't block each other--this may be the same
1323       // symbol name with different section types.
1324       return true;
1325     }
1326 }
1327
1328 // Write out data not associated with a section or the symbol table.
1329
1330 void
1331 Layout::write_data(const Symbol_table* symtab, const Target* target,
1332                    Output_file* of) const
1333 {
1334   const Output_section* symtab_section = this->symtab_section_;
1335   for (Section_list::const_iterator p = this->section_list_.begin();
1336        p != this->section_list_.end();
1337        ++p)
1338     {
1339       if ((*p)->needs_symtab_index())
1340         {
1341           gold_assert(symtab_section != NULL);
1342           unsigned int index = (*p)->symtab_index();
1343           gold_assert(index > 0 && index != -1U);
1344           off_t off = (symtab_section->offset()
1345                        + index * symtab_section->entsize());
1346           symtab->write_section_symbol(target, *p, of, off);
1347         }
1348     }
1349
1350   const Output_section* dynsym_section = this->dynsym_section_;
1351   for (Section_list::const_iterator p = this->section_list_.begin();
1352        p != this->section_list_.end();
1353        ++p)
1354     {
1355       if ((*p)->needs_dynsym_index())
1356         {
1357           gold_assert(dynsym_section != NULL);
1358           unsigned int index = (*p)->dynsym_index();
1359           gold_assert(index > 0 && index != -1U);
1360           off_t off = (dynsym_section->offset()
1361                        + index * dynsym_section->entsize());
1362           symtab->write_section_symbol(target, *p, of, off);
1363         }
1364     }
1365
1366   // Write out the Output_sections.  Most won't have anything to
1367   // write, since most of the data will come from input sections which
1368   // are handled elsewhere.  But some Output_sections do have
1369   // Output_data.
1370   for (Section_list::const_iterator p = this->section_list_.begin();
1371        p != this->section_list_.end();
1372        ++p)
1373     (*p)->write(of);
1374
1375   // Write out the Output_data which are not in an Output_section.
1376   for (Data_list::const_iterator p = this->special_output_list_.begin();
1377        p != this->special_output_list_.end();
1378        ++p)
1379     (*p)->write(of);
1380 }
1381
1382 // Write_data_task methods.
1383
1384 // We can always run this task.
1385
1386 Task::Is_runnable_type
1387 Write_data_task::is_runnable(Workqueue*)
1388 {
1389   return IS_RUNNABLE;
1390 }
1391
1392 // We need to unlock FINAL_BLOCKER when finished.
1393
1394 Task_locker*
1395 Write_data_task::locks(Workqueue* workqueue)
1396 {
1397   return new Task_locker_block(*this->final_blocker_, workqueue);
1398 }
1399
1400 // Run the task--write out the data.
1401
1402 void
1403 Write_data_task::run(Workqueue*)
1404 {
1405   this->layout_->write_data(this->symtab_, this->target_, this->of_);
1406 }
1407
1408 // Write_symbols_task methods.
1409
1410 // We can always run this task.
1411
1412 Task::Is_runnable_type
1413 Write_symbols_task::is_runnable(Workqueue*)
1414 {
1415   return IS_RUNNABLE;
1416 }
1417
1418 // We need to unlock FINAL_BLOCKER when finished.
1419
1420 Task_locker*
1421 Write_symbols_task::locks(Workqueue* workqueue)
1422 {
1423   return new Task_locker_block(*this->final_blocker_, workqueue);
1424 }
1425
1426 // Run the task--write out the symbols.
1427
1428 void
1429 Write_symbols_task::run(Workqueue*)
1430 {
1431   this->symtab_->write_globals(this->target_, this->sympool_, this->dynpool_,
1432                                this->of_);
1433 }
1434
1435 // Close_task_runner methods.
1436
1437 // Run the task--close the file.
1438
1439 void
1440 Close_task_runner::run(Workqueue*)
1441 {
1442   this->of_->close();
1443 }
1444
1445 // Instantiate the templates we need.  We could use the configure
1446 // script to restrict this to only the ones for implemented targets.
1447
1448 template
1449 Output_section*
1450 Layout::layout<32, false>(Relobj* object, unsigned int shndx, const char* name,
1451                           const elfcpp::Shdr<32, false>& shdr, off_t*);
1452
1453 template
1454 Output_section*
1455 Layout::layout<32, true>(Relobj* object, unsigned int shndx, const char* name,
1456                          const elfcpp::Shdr<32, true>& shdr, off_t*);
1457
1458 template
1459 Output_section*
1460 Layout::layout<64, false>(Relobj* object, unsigned int shndx, const char* name,
1461                           const elfcpp::Shdr<64, false>& shdr, off_t*);
1462
1463 template
1464 Output_section*
1465 Layout::layout<64, true>(Relobj* object, unsigned int shndx, const char* name,
1466                          const elfcpp::Shdr<64, true>& shdr, off_t*);
1467
1468
1469 } // End namespace gold.