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
 614           // FIXME: This should depend on the -n and -N options.
 615           (*p)->set_minimum_addralign(target->common_pagesize());
 616
 617           if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0)
 618             {
 619               uint64_t align = (*p)->addralign();
 620
 621               addr = align_address(addr, align);
 622               aligned_addr = addr;
 623               if ((addr & (abi_pagesize - 1)) != 0)
 624                 addr = addr + abi_pagesize;
 625             }
 626
 627           unsigned int shndx_hold = *pshndx;
 628           off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
 629           uint64_t new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
 630
 631           // Now that we know the size of this segment, we may be able
 632           // to save a page in memory, at the cost of wasting some
 633           // file space, by instead aligning to the start of a new
 634           // page.  Here we use the real machine page size rather than
 635           // the ABI mandated page size.
 636
 637           if (aligned_addr != addr)
 638             {
 639               uint64_t common_pagesize = target->common_pagesize();
 640               uint64_t first_off = (common_pagesize
 641                                     - (aligned_addr
 642                                        & (common_pagesize - 1)));
 643               uint64_t last_off = new_addr & (common_pagesize - 1);
 644               if (first_off > 0
 645                   && last_off > 0
 646                   && ((aligned_addr & ~ (common_pagesize - 1))
 647                       != (new_addr & ~ (common_pagesize - 1)))
 648                   && first_off + last_off <= common_pagesize)
 649                 {
 650                   *pshndx = shndx_hold;
 651                   addr = align_address(aligned_addr, common_pagesize);
 652                   off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
 653                   new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
 654                 }
 655             }
 656
 657           addr = new_addr;
 658
 659           if (((*p)->flags() & elfcpp::PF_W) == 0)
 660             was_readonly = true;
 661         }
 662     }
 663
 664   // Handle the non-PT_LOAD segments, setting their offsets from their
 665   // section's offsets.
 666   for (Segment_list::iterator p = this->segment_list_.begin();
 667        p != this->segment_list_.end();
 668        ++p)
 669     {
 670       if ((*p)->type() != elfcpp::PT_LOAD)
 671         (*p)->set_offset();
 672     }
 673
 674   return off;
 675 }
 676
 677 // Set the file offset of all the sections not associated with a
 678 // segment.
 679
 680 off_t
 681 Layout::set_section_offsets(off_t off, unsigned int* pshndx)
 682 {
 683   for (Section_list::iterator p = this->unattached_section_list_.begin();
 684        p != this->unattached_section_list_.end();
 685        ++p)
 686     {
 687       (*p)->set_out_shndx(*pshndx);
 688       ++*pshndx;
 689       if ((*p)->offset() != -1)
 690         continue;
 691       off = align_address(off, (*p)->addralign());
 692       (*p)->set_address(0, off);
 693       off += (*p)->data_size();
 694     }
 695   return off;
 696 }
 697
 698 // Create the symbol table sections.  Here we also set the final
 699 // values of the symbols.  At this point all the loadable sections are
 700 // fully laid out.
 701
 702 void
 703 Layout::create_symtab_sections(int size, const Input_objects* input_objects,
 704                                Symbol_table* symtab,
 705                                off_t* poff)
 706 {
 707   int symsize;
 708   unsigned int align;
 709   if (size == 32)
 710     {
 711       symsize = elfcpp::Elf_sizes<32>::sym_size;
 712       align = 4;
 713     }
 714   else if (size == 64)
 715     {
 716       symsize = elfcpp::Elf_sizes<64>::sym_size;
 717       align = 8;
 718     }
 719   else
 720     gold_unreachable();
 721
 722   off_t off = *poff;
 723   off = align_address(off, align);
 724   off_t startoff = off;
 725
 726   // Save space for the dummy symbol at the start of the section.  We
 727   // never bother to write this out--it will just be left as zero.
 728   off += symsize;
 729   unsigned int local_symbol_index = 1;
 730
 731   // Add STT_SECTION symbols for each Output section which needs one.
 732   for (Section_list::iterator p = this->section_list_.begin();
 733        p != this->section_list_.end();
 734        ++p)
 735     {
 736       if (!(*p)->needs_symtab_index())
 737         (*p)->set_symtab_index(-1U);
 738       else
 739         {
 740           (*p)->set_symtab_index(local_symbol_index);
 741           ++local_symbol_index;
 742           off += symsize;
 743         }
 744     }
 745
 746   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
 747        p != input_objects->relobj_end();
 748        ++p)
 749     {
 750       Task_lock_obj<Object> tlo(**p);
 751       unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
 752                                                         off,
 753                                                         &this->sympool_);
 754       off += (index - local_symbol_index) * symsize;
 755       local_symbol_index = index;
 756     }
 757
 758   unsigned int local_symcount = local_symbol_index;
 759   gold_assert(local_symcount * symsize == off - startoff);
 760
 761   off_t dynoff;
 762   size_t dyn_global_index;
 763   size_t dyncount;
 764   if (this->dynsym_section_ == NULL)
 765     {
 766       dynoff = 0;
 767       dyn_global_index = 0;
 768       dyncount = 0;
 769     }
 770   else
 771     {
 772       dyn_global_index = this->dynsym_section_->info();
 773       off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
 774       dynoff = this->dynsym_section_->offset() + locsize;
 775       dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
 776       gold_assert(dyncount * symsize
 777                   == this->dynsym_section_->data_size() - locsize);
 778     }
 779
 780   off = symtab->finalize(local_symcount, off, dynoff, dyn_global_index,
 781                          dyncount, &this->sympool_);
 782
 783   this->sympool_.set_string_offsets();
 784
 785   const char* symtab_name = this->namepool_.add(".symtab", NULL);
 786   Output_section* osymtab = this->make_output_section(symtab_name,
 787                                                       elfcpp::SHT_SYMTAB,
 788                                                       0);
 789   this->symtab_section_ = osymtab;
 790
 791   Output_section_data* pos = new Output_data_space(off - startoff,
 792                                                    align);
 793   osymtab->add_output_section_data(pos);
 794
 795   const char* strtab_name = this->namepool_.add(".strtab", NULL);
 796   Output_section* ostrtab = this->make_output_section(strtab_name,
 797                                                       elfcpp::SHT_STRTAB,
 798                                                       0);
 799
 800   Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
 801   ostrtab->add_output_section_data(pstr);
 802
 803   osymtab->set_address(0, startoff);
 804   osymtab->set_link_section(ostrtab);
 805   osymtab->set_info(local_symcount);
 806   osymtab->set_entsize(symsize);
 807
 808   *poff = off;
 809 }
 810
 811 // Create the .shstrtab section, which holds the names of the
 812 // sections.  At the time this is called, we have created all the
 813 // output sections except .shstrtab itself.
 814
 815 Output_section*
 816 Layout::create_shstrtab()
 817 {
 818   // FIXME: We don't need to create a .shstrtab section if we are
 819   // stripping everything.
 820
 821   const char* name = this->namepool_.add(".shstrtab", NULL);
 822
 823   this->namepool_.set_string_offsets();
 824
 825   Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0);
 826
 827   Output_section_data* posd = new Output_data_strtab(&this->namepool_);
 828   os->add_output_section_data(posd);
 829
 830   return os;
 831 }
 832
 833 // Create the section headers.  SIZE is 32 or 64.  OFF is the file
 834 // offset.
 835
 836 Output_section_headers*
 837 Layout::create_shdrs(int size, bool big_endian, off_t* poff)
 838 {
 839   Output_section_headers* oshdrs;
 840   oshdrs = new Output_section_headers(size, big_endian, this,
 841                                       &this->segment_list_,
 842                                       &this->unattached_section_list_,
 843                                       &this->namepool_);
 844   off_t off = align_address(*poff, oshdrs->addralign());
 845   oshdrs->set_address(0, off);
 846   off += oshdrs->data_size();
 847   *poff = off;
 848   this->special_output_list_.push_back(oshdrs);
 849   return oshdrs;
 850 }
 851
 852 // Create the dynamic symbol table.
 853
 854 void
 855 Layout::create_dynamic_symtab(const Target* target, Symbol_table* symtab,
 856                               Output_section **pdynstr,
 857                               unsigned int* plocal_dynamic_count,
 858                               std::vector<Symbol*>* pdynamic_symbols,
 859                               Versions* pversions)
 860 {
 861   // Count all the symbols in the dynamic symbol table, and set the
 862   // dynamic symbol indexes.
 863
 864   // Skip symbol 0, which is always all zeroes.
 865   unsigned int index = 1;
 866
 867   // Add STT_SECTION symbols for each Output section which needs one.
 868   for (Section_list::iterator p = this->section_list_.begin();
 869        p != this->section_list_.end();
 870        ++p)
 871     {
 872       if (!(*p)->needs_dynsym_index())
 873         (*p)->set_dynsym_index(-1U);
 874       else
 875         {
 876           (*p)->set_dynsym_index(index);
 877           ++index;
 878         }
 879     }
 880
 881   // FIXME: Some targets apparently require local symbols in the
 882   // dynamic symbol table.  Here is where we will have to count them,
 883   // and set the dynamic symbol indexes, and add the names to
 884   // this->dynpool_.
 885
 886   unsigned int local_symcount = index;
 887   *plocal_dynamic_count = local_symcount;
 888
 889   // FIXME: We have to tell set_dynsym_indexes whether the
 890   // -E/--export-dynamic option was used.
 891   index = symtab->set_dynsym_indexes(&this->options_, target, index,
 892                                      pdynamic_symbols, &this->dynpool_,
 893                                      pversions);
 894
 895   int symsize;
 896   unsigned int align;
 897   const int size = target->get_size();
 898   if (size == 32)
 899     {
 900       symsize = elfcpp::Elf_sizes<32>::sym_size;
 901       align = 4;
 902     }
 903   else if (size == 64)
 904     {
 905       symsize = elfcpp::Elf_sizes<64>::sym_size;
 906       align = 8;
 907     }
 908   else
 909     gold_unreachable();
 910
 911   // Create the dynamic symbol table section.
 912
 913   const char* dynsym_name = this->namepool_.add(".dynsym", NULL);
 914   Output_section* dynsym = this->make_output_section(dynsym_name,
 915                                                      elfcpp::SHT_DYNSYM,
 916                                                      elfcpp::SHF_ALLOC);
 917
 918   Output_section_data* odata = new Output_data_space(index * symsize,
 919                                                      align);
 920   dynsym->add_output_section_data(odata);
 921
 922   dynsym->set_info(local_symcount);
 923   dynsym->set_entsize(symsize);
 924   dynsym->set_addralign(align);
 925
 926   this->dynsym_section_ = dynsym;
 927
 928   Output_data_dynamic* const odyn = this->dynamic_data_;
 929   odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
 930   odyn->add_constant(elfcpp::DT_SYMENT, symsize);
 931
 932   // Create the dynamic string table section.
 933
 934   const char* dynstr_name = this->namepool_.add(".dynstr", NULL);
 935   Output_section* dynstr = this->make_output_section(dynstr_name,
 936                                                      elfcpp::SHT_STRTAB,
 937                                                      elfcpp::SHF_ALLOC);
 938
 939   Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
 940   dynstr->add_output_section_data(strdata);
 941
 942   dynsym->set_link_section(dynstr);
 943   this->dynamic_section_->set_link_section(dynstr);
 944
 945   odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
 946   odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
 947
 948   *pdynstr = dynstr;
 949
 950   // Create the hash tables.
 951
 952   // FIXME: We need an option to create a GNU hash table.
 953
 954   unsigned char* phash;
 955   unsigned int hashlen;
 956   Dynobj::create_elf_hash_table(target, *pdynamic_symbols, local_symcount,
 957                                 &phash, &hashlen);
 958
 959   const char* hash_name = this->namepool_.add(".hash", NULL);
 960   Output_section* hashsec = this->make_output_section(hash_name,
 961                                                       elfcpp::SHT_HASH,
 962                                                       elfcpp::SHF_ALLOC);
 963
 964   Output_section_data* hashdata = new Output_data_const_buffer(phash,
 965                                                                hashlen,
 966                                                                align);
 967   hashsec->add_output_section_data(hashdata);
 968
 969   hashsec->set_link_section(dynsym);
 970   hashsec->set_entsize(4);
 971
 972   odyn->add_section_address(elfcpp::DT_HASH, hashsec);
 973 }
 974
 975 // Create the version sections.
 976
 977 void
 978 Layout::create_version_sections(const Target* target, const Versions* versions,
 979                                 unsigned int local_symcount,
 980                                 const std::vector<Symbol*>& dynamic_symbols,
 981                                 const Output_section* dynstr)
 982 {
 983   if (!versions->any_defs() && !versions->any_needs())
 984     return;
 985
 986   if (target->get_size() == 32)
 987     {
 988       if (target->is_big_endian())
 989         this->sized_create_version_sections SELECT_SIZE_ENDIAN_NAME(32, true)(
 990             versions, local_symcount, dynamic_symbols, dynstr
 991             SELECT_SIZE_ENDIAN(32, true));
 992       else
 993         this->sized_create_version_sections SELECT_SIZE_ENDIAN_NAME(32, false)(
 994             versions, local_symcount, dynamic_symbols, dynstr
 995             SELECT_SIZE_ENDIAN(32, false));
 996     }
 997   else if (target->get_size() == 64)
 998     {
 999       if (target->is_big_endian())
1000         this->sized_create_version_sections SELECT_SIZE_ENDIAN_NAME(64, true)(
1001             versions, local_symcount, dynamic_symbols, dynstr
1002             SELECT_SIZE_ENDIAN(64, true));
1003       else
1004         this->sized_create_version_sections SELECT_SIZE_ENDIAN_NAME(64, false)(
1005             versions, local_symcount, dynamic_symbols, dynstr
1006             SELECT_SIZE_ENDIAN(64, false));
1007     }
1008   else
1009     gold_unreachable();
1010 }
1011
1012 // Create the version sections, sized version.
1013
1014 template<int size, bool big_endian>
1015 void
1016 Layout::sized_create_version_sections(
1017     const Versions* versions,
1018     unsigned int local_symcount,
1019     const std::vector<Symbol*>& dynamic_symbols,
1020     const Output_section* dynstr
1021     ACCEPT_SIZE_ENDIAN)
1022 {
1023   const char* vname = this->namepool_.add(".gnu.version", NULL);
1024   Output_section* vsec = this->make_output_section(vname,
1025                                                    elfcpp::SHT_GNU_versym,
1026                                                    elfcpp::SHF_ALLOC);
1027
1028   unsigned char* vbuf;
1029   unsigned int vsize;
1030   versions->symbol_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)(
1031       &this->dynpool_, local_symcount, dynamic_symbols, &vbuf, &vsize
1032       SELECT_SIZE_ENDIAN(size, big_endian));
1033
1034   Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2);
1035
1036   vsec->add_output_section_data(vdata);
1037   vsec->set_entsize(2);
1038   vsec->set_link_section(this->dynsym_section_);
1039
1040   Output_data_dynamic* const odyn = this->dynamic_data_;
1041   odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
1042
1043   if (versions->any_defs())
1044     {
1045       const char* vdname = this->namepool_.add(".gnu.version_d", NULL);
1046       Output_section *vdsec;
1047       vdsec = this->make_output_section(vdname, elfcpp::SHT_GNU_verdef,
1048                                         elfcpp::SHF_ALLOC);
1049
1050       unsigned char* vdbuf;
1051       unsigned int vdsize;
1052       unsigned int vdentries;
1053       versions->def_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)(
1054           &this->dynpool_, &vdbuf, &vdsize, &vdentries
1055           SELECT_SIZE_ENDIAN(size, big_endian));
1056
1057       Output_section_data* vddata = new Output_data_const_buffer(vdbuf,
1058                                                                  vdsize,
1059                                                                  4);
1060
1061       vdsec->add_output_section_data(vddata);
1062       vdsec->set_link_section(dynstr);
1063       vdsec->set_info(vdentries);
1064
1065       odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
1066       odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
1067     }
1068
1069   if (versions->any_needs())
1070     {
1071       const char* vnname = this->namepool_.add(".gnu.version_r", NULL);
1072       Output_section* vnsec;
1073       vnsec = this->make_output_section(vnname, elfcpp::SHT_GNU_verneed,
1074                                         elfcpp::SHF_ALLOC);
1075
1076       unsigned char* vnbuf;
1077       unsigned int vnsize;
1078       unsigned int vnentries;
1079       versions->need_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)
1080         (&this->dynpool_, &vnbuf, &vnsize, &vnentries
1081          SELECT_SIZE_ENDIAN(size, big_endian));
1082
1083       Output_section_data* vndata = new Output_data_const_buffer(vnbuf,
1084                                                                  vnsize,
1085                                                                  4);
1086
1087       vnsec->add_output_section_data(vndata);
1088       vnsec->set_link_section(dynstr);
1089       vnsec->set_info(vnentries);
1090
1091       odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
1092       odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
1093     }
1094 }
1095
1096 // Create the .interp section and PT_INTERP segment.
1097
1098 void
1099 Layout::create_interp(const Target* target)
1100 {
1101   const char* interp = this->options_.dynamic_linker();
1102   if (interp == NULL)
1103     {
1104       interp = target->dynamic_linker();
1105       gold_assert(interp != NULL);
1106     }
1107
1108   size_t len = strlen(interp) + 1;
1109
1110   Output_section_data* odata = new Output_data_const(interp, len, 1);
1111
1112   const char* interp_name = this->namepool_.add(".interp", NULL);
1113   Output_section* osec = this->make_output_section(interp_name,
1114                                                    elfcpp::SHT_PROGBITS,
1115                                                    elfcpp::SHF_ALLOC);
1116   osec->add_output_section_data(odata);
1117
1118   Output_segment* oseg = new Output_segment(elfcpp::PT_INTERP, elfcpp::PF_R);
1119   this->segment_list_.push_back(oseg);
1120   oseg->add_initial_output_section(osec, elfcpp::PF_R);
1121 }
1122
1123 // Finish the .dynamic section and PT_DYNAMIC segment.
1124
1125 void
1126 Layout::finish_dynamic_section(const Input_objects* input_objects,
1127                                const Symbol_table* symtab)
1128 {
1129   Output_segment* oseg = new Output_segment(elfcpp::PT_DYNAMIC,
1130                                             elfcpp::PF_R | elfcpp::PF_W);
1131   this->segment_list_.push_back(oseg);
1132   oseg->add_initial_output_section(this->dynamic_section_,
1133                                    elfcpp::PF_R | elfcpp::PF_W);
1134
1135   Output_data_dynamic* const odyn = this->dynamic_data_;
1136
1137   for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
1138        p != input_objects->dynobj_end();
1139        ++p)
1140     {
1141       // FIXME: Handle --as-needed.
1142       odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
1143     }
1144
1145   // FIXME: Support --init and --fini.
1146   Symbol* sym = symtab->lookup("_init");
1147   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
1148     odyn->add_symbol(elfcpp::DT_INIT, sym);
1149
1150   sym = symtab->lookup("_fini");
1151   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
1152     odyn->add_symbol(elfcpp::DT_FINI, sym);
1153
1154   // FIXME: Support DT_INIT_ARRAY and DT_FINI_ARRAY.
1155
1156   // Add a DT_RPATH entry if needed.
1157   const General_options::Dir_list& rpath(this->options_.rpath());
1158   if (!rpath.empty())
1159     {
1160       std::string rpath_val;
1161       for (General_options::Dir_list::const_iterator p = rpath.begin();
1162            p != rpath.end();
1163            ++p)
1164         {
1165           if (rpath_val.empty())
1166             rpath_val = *p;
1167           else
1168             {
1169               // Eliminate duplicates.
1170               General_options::Dir_list::const_iterator q;
1171               for (q = rpath.begin(); q != p; ++q)
1172                 if (strcmp(*q, *p) == 0)
1173                   break;
1174               if (q == p)
1175                 {
1176                   rpath_val += ':';
1177                   rpath_val += *p;
1178                 }
1179             }
1180         }
1181
1182       odyn->add_string(elfcpp::DT_RPATH, rpath_val);
1183     }
1184 }
1185
1186 // The mapping of .gnu.linkonce section names to real section names.
1187
1188 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
1189 const Layout::Linkonce_mapping Layout::linkonce_mapping[] =
1190 {
1191   MAPPING_INIT("d.rel.ro", ".data.rel.ro"),     // Must be before "d".
1192   MAPPING_INIT("t", ".text"),
1193   MAPPING_INIT("r", ".rodata"),
1194   MAPPING_INIT("d", ".data"),
1195   MAPPING_INIT("b", ".bss"),
1196   MAPPING_INIT("s", ".sdata"),
1197   MAPPING_INIT("sb", ".sbss"),
1198   MAPPING_INIT("s2", ".sdata2"),
1199   MAPPING_INIT("sb2", ".sbss2"),
1200   MAPPING_INIT("wi", ".debug_info"),
1201   MAPPING_INIT("td", ".tdata"),
1202   MAPPING_INIT("tb", ".tbss"),
1203   MAPPING_INIT("lr", ".lrodata"),
1204   MAPPING_INIT("l", ".ldata"),
1205   MAPPING_INIT("lb", ".lbss"),
1206 };
1207 #undef MAPPING_INIT
1208
1209 const int Layout::linkonce_mapping_count =
1210   sizeof(Layout::linkonce_mapping) / sizeof(Layout::linkonce_mapping[0]);
1211
1212 // Return the name of the output section to use for a .gnu.linkonce
1213 // section.  This is based on the default ELF linker script of the old
1214 // GNU linker.  For example, we map a name like ".gnu.linkonce.t.foo"
1215 // to ".text".  Set *PLEN to the length of the name.  *PLEN is
1216 // initialized to the length of NAME.
1217
1218 const char*
1219 Layout::linkonce_output_name(const char* name, size_t *plen)
1220 {
1221   const char* s = name + sizeof(".gnu.linkonce") - 1;
1222   if (*s != '.')
1223     return name;
1224   ++s;
1225   const Linkonce_mapping* plm = linkonce_mapping;
1226   for (int i = 0; i < linkonce_mapping_count; ++i, ++plm)
1227     {
1228       if (strncmp(s, plm->from, plm->fromlen) == 0 && s[plm->fromlen] == '.')
1229         {
1230           *plen = plm->tolen;
1231           return plm->to;
1232         }
1233     }
1234   return name;
1235 }
1236
1237 // Choose the output section name to use given an input section name.
1238 // Set *PLEN to the length of the name.  *PLEN is initialized to the
1239 // length of NAME.
1240
1241 const char*
1242 Layout::output_section_name(const char* name, size_t* plen)
1243 {
1244   if (Layout::is_linkonce(name))
1245     {
1246       // .gnu.linkonce sections are laid out as though they were named
1247       // for the sections are placed into.
1248       return Layout::linkonce_output_name(name, plen);
1249     }
1250
1251   // If the section name has no '.', or only an initial '.', we use
1252   // the name unchanged (i.e., ".text" is unchanged).
1253
1254   // Otherwise, if the section name does not include ".rel", we drop
1255   // the last '.'  and everything that follows (i.e., ".text.XXX"
1256   // becomes ".text").
1257
1258   // Otherwise, if the section name has zero or one '.' after the
1259   // ".rel", we use the name unchanged (i.e., ".rel.text" is
1260   // unchanged).
1261
1262   // Otherwise, we drop the last '.' and everything that follows
1263   // (i.e., ".rel.text.XXX" becomes ".rel.text").
1264
1265   const char* s = name;
1266   if (*s == '.')
1267     ++s;
1268   const char* sdot = strchr(s, '.');
1269   if (sdot == NULL)
1270     return name;
1271
1272   const char* srel = strstr(s, ".rel");
1273   if (srel == NULL)
1274     {
1275       *plen = sdot - name;
1276       return name;
1277     }
1278
1279   sdot = strchr(srel + 1, '.');
1280   if (sdot == NULL)
1281     return name;
1282   sdot = strchr(sdot + 1, '.');
1283   if (sdot == NULL)
1284     return name;
1285
1286   *plen = sdot - name;
1287   return name;
1288 }
1289
1290 // Record the signature of a comdat section, and return whether to
1291 // include it in the link.  If GROUP is true, this is a regular
1292 // section group.  If GROUP is false, this is a group signature
1293 // derived from the name of a linkonce section.  We want linkonce
1294 // signatures and group signatures to block each other, but we don't
1295 // want a linkonce signature to block another linkonce signature.
1296
1297 bool
1298 Layout::add_comdat(const char* signature, bool group)
1299 {
1300   std::string sig(signature);
1301   std::pair<Signatures::iterator, bool> ins(
1302     this->signatures_.insert(std::make_pair(sig, group)));
1303
1304   if (ins.second)
1305     {
1306       // This is the first time we've seen this signature.
1307       return true;
1308     }
1309
1310   if (ins.first->second)
1311     {
1312       // We've already seen a real section group with this signature.
1313       return false;
1314     }
1315   else if (group)
1316     {
1317       // This is a real section group, and we've already seen a
1318       // linkonce section with tihs signature.  Record that we've seen
1319       // a section group, and don't include this section group.
1320       ins.first->second = true;
1321       return false;
1322     }
1323   else
1324     {
1325       // We've already seen a linkonce section and this is a linkonce
1326       // section.  These don't block each other--this may be the same
1327       // symbol name with different section types.
1328       return true;
1329     }
1330 }
1331
1332 // Write out data not associated with a section or the symbol table.
1333
1334 void
1335 Layout::write_data(const Symbol_table* symtab, const Target* target,
1336                    Output_file* of) const
1337 {
1338   const Output_section* symtab_section = this->symtab_section_;
1339   for (Section_list::const_iterator p = this->section_list_.begin();
1340        p != this->section_list_.end();
1341        ++p)
1342     {
1343       if ((*p)->needs_symtab_index())
1344         {
1345           gold_assert(symtab_section != NULL);
1346           unsigned int index = (*p)->symtab_index();
1347           gold_assert(index > 0 && index != -1U);
1348           off_t off = (symtab_section->offset()
1349                        + index * symtab_section->entsize());
1350           symtab->write_section_symbol(target, *p, of, off);
1351         }
1352     }
1353
1354   const Output_section* dynsym_section = this->dynsym_section_;
1355   for (Section_list::const_iterator p = this->section_list_.begin();
1356        p != this->section_list_.end();
1357        ++p)
1358     {
1359       if ((*p)->needs_dynsym_index())
1360         {
1361           gold_assert(dynsym_section != NULL);
1362           unsigned int index = (*p)->dynsym_index();
1363           gold_assert(index > 0 && index != -1U);
1364           off_t off = (dynsym_section->offset()
1365                        + index * dynsym_section->entsize());
1366           symtab->write_section_symbol(target, *p, of, off);
1367         }
1368     }
1369
1370   // Write out the Output_sections.  Most won't have anything to
1371   // write, since most of the data will come from input sections which
1372   // are handled elsewhere.  But some Output_sections do have
1373   // Output_data.
1374   for (Section_list::const_iterator p = this->section_list_.begin();
1375        p != this->section_list_.end();
1376        ++p)
1377     (*p)->write(of);
1378
1379   // Write out the Output_data which are not in an Output_section.
1380   for (Data_list::const_iterator p = this->special_output_list_.begin();
1381        p != this->special_output_list_.end();
1382        ++p)
1383     (*p)->write(of);
1384 }
1385
1386 // Write_data_task methods.
1387
1388 // We can always run this task.
1389
1390 Task::Is_runnable_type
1391 Write_data_task::is_runnable(Workqueue*)
1392 {
1393   return IS_RUNNABLE;
1394 }
1395
1396 // We need to unlock FINAL_BLOCKER when finished.
1397
1398 Task_locker*
1399 Write_data_task::locks(Workqueue* workqueue)
1400 {
1401   return new Task_locker_block(*this->final_blocker_, workqueue);
1402 }
1403
1404 // Run the task--write out the data.
1405
1406 void
1407 Write_data_task::run(Workqueue*)
1408 {
1409   this->layout_->write_data(this->symtab_, this->target_, this->of_);
1410 }
1411
1412 // Write_symbols_task methods.
1413
1414 // We can always run this task.
1415
1416 Task::Is_runnable_type
1417 Write_symbols_task::is_runnable(Workqueue*)
1418 {
1419   return IS_RUNNABLE;
1420 }
1421
1422 // We need to unlock FINAL_BLOCKER when finished.
1423
1424 Task_locker*
1425 Write_symbols_task::locks(Workqueue* workqueue)
1426 {
1427   return new Task_locker_block(*this->final_blocker_, workqueue);
1428 }
1429
1430 // Run the task--write out the symbols.
1431
1432 void
1433 Write_symbols_task::run(Workqueue*)
1434 {
1435   this->symtab_->write_globals(this->target_, this->sympool_, this->dynpool_,
1436                                this->of_);
1437 }
1438
1439 // Close_task_runner methods.
1440
1441 // Run the task--close the file.
1442
1443 void
1444 Close_task_runner::run(Workqueue*)
1445 {
1446   this->of_->close();
1447 }
1448
1449 // Instantiate the templates we need.  We could use the configure
1450 // script to restrict this to only the ones for implemented targets.
1451
1452 template
1453 Output_section*
1454 Layout::layout<32, false>(Relobj* object, unsigned int shndx, const char* name,
1455                           const elfcpp::Shdr<32, false>& shdr, off_t*);
1456
1457 template
1458 Output_section*
1459 Layout::layout<32, true>(Relobj* object, unsigned int shndx, const char* name,
1460                          const elfcpp::Shdr<32, true>& shdr, off_t*);
1461
1462 template
1463 Output_section*
1464 Layout::layout<64, false>(Relobj* object, unsigned int shndx, const char* name,
1465                           const elfcpp::Shdr<64, false>& shdr, off_t*);
1466
1467 template
1468 Output_section*
1469 Layout::layout<64, true>(Relobj* object, unsigned int shndx, const char* name,
1470                          const elfcpp::Shdr<64, true>& shdr, off_t*);
1471
1472
1473 } // End namespace gold.