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 "parameters.h"
  11 #include "output.h"
  12 #include "symtab.h"
  13 #include "dynobj.h"
  14 #include "layout.h"
  15
  16 namespace gold
  17 {
  18
  19 // Layout_task_runner methods.
  20
  21 // Lay out the sections.  This is called after all the input objects
  22 // have been read.
  23
  24 void
  25 Layout_task_runner::run(Workqueue* workqueue)
  26 {
  27   off_t file_size = this->layout_->finalize(this->input_objects_,
  28                                             this->symtab_);
  29
  30   // Now we know the final size of the output file and we know where
  31   // each piece of information goes.
  32   Output_file* of = new Output_file(this->options_,
  33                                     this->input_objects_->target());
  34   of->open(file_size);
  35
  36   // Queue up the final set of tasks.
  37   gold::queue_final_tasks(this->options_, this->input_objects_,
  38                           this->symtab_, this->layout_, workqueue, of);
  39 }
  40
  41 // Layout methods.
  42
  43 Layout::Layout(const General_options& options)
  44   : options_(options), namepool_(), sympool_(), dynpool_(), signatures_(),
  45     section_name_map_(), segment_list_(), section_list_(),
  46     unattached_section_list_(), special_output_list_(),
  47     tls_segment_(NULL), symtab_section_(NULL),
  48     dynsym_section_(NULL), dynamic_section_(NULL), dynamic_data_(NULL)
  49 {
  50   // Make space for more than enough segments for a typical file.
  51   // This is just for efficiency--it's OK if we wind up needing more.
  52   this->segment_list_.reserve(12);
  53
  54   // We expect three unattached Output_data objects: the file header,
  55   // the segment headers, and the section headers.
  56   this->special_output_list_.reserve(3);
  57 }
  58
  59 // Hash a key we use to look up an output section mapping.
  60
  61 size_t
  62 Layout::Hash_key::operator()(const Layout::Key& k) const
  63 {
  64  return k.first + k.second.first + k.second.second;
  65 }
  66
  67 // Whether to include this section in the link.
  68
  69 template<int size, bool big_endian>
  70 bool
  71 Layout::include_section(Object*, const char*,
  72                         const elfcpp::Shdr<size, big_endian>& shdr)
  73 {
  74   // Some section types are never linked.  Some are only linked when
  75   // doing a relocateable link.
  76   switch (shdr.get_sh_type())
  77     {
  78     case elfcpp::SHT_NULL:
  79     case elfcpp::SHT_SYMTAB:
  80     case elfcpp::SHT_DYNSYM:
  81     case elfcpp::SHT_STRTAB:
  82     case elfcpp::SHT_HASH:
  83     case elfcpp::SHT_DYNAMIC:
  84     case elfcpp::SHT_SYMTAB_SHNDX:
  85       return false;
  86
  87     case elfcpp::SHT_RELA:
  88     case elfcpp::SHT_REL:
  89     case elfcpp::SHT_GROUP:
  90       return parameters->output_is_object();
  91
  92     default:
  93       // FIXME: Handle stripping debug sections here.
  94       return true;
  95     }
  96 }
  97
  98 // Return an output section named NAME, or NULL if there is none.
  99
 100 Output_section*
 101 Layout::find_output_section(const char* name) const
 102 {
 103   for (Section_name_map::const_iterator p = this->section_name_map_.begin();
 104        p != this->section_name_map_.end();
 105        ++p)
 106     if (strcmp(p->second->name(), name) == 0)
 107       return p->second;
 108   return NULL;
 109 }
 110
 111 // Return an output segment of type TYPE, with segment flags SET set
 112 // and segment flags CLEAR clear.  Return NULL if there is none.
 113
 114 Output_segment*
 115 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
 116                             elfcpp::Elf_Word clear) const
 117 {
 118   for (Segment_list::const_iterator p = this->segment_list_.begin();
 119        p != this->segment_list_.end();
 120        ++p)
 121     if (static_cast<elfcpp::PT>((*p)->type()) == type
 122         && ((*p)->flags() & set) == set
 123         && ((*p)->flags() & clear) == 0)
 124       return *p;
 125   return NULL;
 126 }
 127
 128 // Return the output section to use for section NAME with type TYPE
 129 // and section flags FLAGS.
 130
 131 Output_section*
 132 Layout::get_output_section(const char* name, Stringpool::Key name_key,
 133                            elfcpp::Elf_Word type, elfcpp::Elf_Xword flags)
 134 {
 135   // We should ignore some flags.
 136   flags &= ~ (elfcpp::SHF_INFO_LINK
 137               | elfcpp::SHF_LINK_ORDER
 138               | elfcpp::SHF_GROUP
 139               | elfcpp::SHF_MERGE
 140               | elfcpp::SHF_STRINGS);
 141
 142   const Key key(name_key, std::make_pair(type, flags));
 143   const std::pair<Key, Output_section*> v(key, NULL);
 144   std::pair<Section_name_map::iterator, bool> ins(
 145     this->section_name_map_.insert(v));
 146
 147   if (!ins.second)
 148     return ins.first->second;
 149   else
 150     {
 151       // This is the first time we've seen this name/type/flags
 152       // combination.
 153       Output_section* os = this->make_output_section(name, type, flags);
 154       ins.first->second = os;
 155       return os;
 156     }
 157 }
 158
 159 // Return the output section to use for input section SHNDX, with name
 160 // NAME, with header HEADER, from object OBJECT.  Set *OFF to the
 161 // offset of this input section without the output section.
 162
 163 template<int size, bool big_endian>
 164 Output_section*
 165 Layout::layout(Relobj* object, unsigned int shndx, const char* name,
 166                const elfcpp::Shdr<size, big_endian>& shdr, off_t* off)
 167 {
 168   if (!this->include_section(object, name, shdr))
 169     return NULL;
 170
 171   // If we are not doing a relocateable link, choose the name to use
 172   // for the output section.
 173   size_t len = strlen(name);
 174   if (!parameters->output_is_object())
 175     name = Layout::output_section_name(name, &len);
 176
 177   // FIXME: Handle SHF_OS_NONCONFORMING here.
 178
 179   // Canonicalize the section name.
 180   Stringpool::Key name_key;
 181   name = this->namepool_.add(name, len, &name_key);
 182
 183   // Find the output section.  The output section is selected based on
 184   // the section name, type, and flags.
 185   Output_section* os = this->get_output_section(name, name_key,
 186                                                 shdr.get_sh_type(),
 187                                                 shdr.get_sh_flags());
 188
 189   // FIXME: Handle SHF_LINK_ORDER somewhere.
 190
 191   *off = os->add_input_section(object, shndx, name, shdr);
 192
 193   return os;
 194 }
 195
 196 // Add POSD to an output section using NAME, TYPE, and FLAGS.
 197
 198 void
 199 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
 200                                 elfcpp::Elf_Xword flags,
 201                                 Output_section_data* posd)
 202 {
 203   // Canonicalize the name.
 204   Stringpool::Key name_key;
 205   name = this->namepool_.add(name, &name_key);
 206
 207   Output_section* os = this->get_output_section(name, name_key, type, flags);
 208   os->add_output_section_data(posd);
 209 }
 210
 211 // Map section flags to segment flags.
 212
 213 elfcpp::Elf_Word
 214 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
 215 {
 216   elfcpp::Elf_Word ret = elfcpp::PF_R;
 217   if ((flags & elfcpp::SHF_WRITE) != 0)
 218     ret |= elfcpp::PF_W;
 219   if ((flags & elfcpp::SHF_EXECINSTR) != 0)
 220     ret |= elfcpp::PF_X;
 221   return ret;
 222 }
 223
 224 // Make a new Output_section, and attach it to segments as
 225 // appropriate.
 226
 227 Output_section*
 228 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
 229                             elfcpp::Elf_Xword flags)
 230 {
 231   Output_section* os = new Output_section(name, type, flags);
 232   this->section_list_.push_back(os);
 233
 234   if ((flags & elfcpp::SHF_ALLOC) == 0)
 235     this->unattached_section_list_.push_back(os);
 236   else
 237     {
 238       // This output section goes into a PT_LOAD segment.
 239
 240       elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
 241
 242       // The only thing we really care about for PT_LOAD segments is
 243       // whether or not they are writable, so that is how we search
 244       // for them.  People who need segments sorted on some other
 245       // basis will have to wait until we implement a mechanism for
 246       // them to describe the segments they want.
 247
 248       Segment_list::const_iterator p;
 249       for (p = this->segment_list_.begin();
 250            p != this->segment_list_.end();
 251            ++p)
 252         {
 253           if ((*p)->type() == elfcpp::PT_LOAD
 254               && ((*p)->flags() & elfcpp::PF_W) == (seg_flags & elfcpp::PF_W))
 255             {
 256               (*p)->add_output_section(os, seg_flags);
 257               break;
 258             }
 259         }
 260
 261       if (p == this->segment_list_.end())
 262         {
 263           Output_segment* oseg = new Output_segment(elfcpp::PT_LOAD,
 264                                                     seg_flags);
 265           this->segment_list_.push_back(oseg);
 266           oseg->add_output_section(os, seg_flags);
 267         }
 268
 269       // If we see a loadable SHT_NOTE section, we create a PT_NOTE
 270       // segment.
 271       if (type == elfcpp::SHT_NOTE)
 272         {
 273           // See if we already have an equivalent PT_NOTE segment.
 274           for (p = this->segment_list_.begin();
 275                p != segment_list_.end();
 276                ++p)
 277             {
 278               if ((*p)->type() == elfcpp::PT_NOTE
 279                   && (((*p)->flags() & elfcpp::PF_W)
 280                       == (seg_flags & elfcpp::PF_W)))
 281                 {
 282                   (*p)->add_output_section(os, seg_flags);
 283                   break;
 284                 }
 285             }
 286
 287           if (p == this->segment_list_.end())
 288             {
 289               Output_segment* oseg = new Output_segment(elfcpp::PT_NOTE,
 290                                                         seg_flags);
 291               this->segment_list_.push_back(oseg);
 292               oseg->add_output_section(os, seg_flags);
 293             }
 294         }
 295
 296       // If we see a loadable SHF_TLS section, we create a PT_TLS
 297       // segment.  There can only be one such segment.
 298       if ((flags & elfcpp::SHF_TLS) != 0)
 299         {
 300           if (this->tls_segment_ == NULL)
 301             {
 302               this->tls_segment_ = new Output_segment(elfcpp::PT_TLS,
 303                                                       seg_flags);
 304               this->segment_list_.push_back(this->tls_segment_);
 305             }
 306           this->tls_segment_->add_output_section(os, seg_flags);
 307         }
 308     }
 309
 310   return os;
 311 }
 312
 313 // Create the dynamic sections which are needed before we read the
 314 // relocs.
 315
 316 void
 317 Layout::create_initial_dynamic_sections(const Input_objects* input_objects,
 318                                         Symbol_table* symtab)
 319 {
 320   if (!input_objects->any_dynamic())
 321     return;
 322
 323   const char* dynamic_name = this->namepool_.add(".dynamic", NULL);
 324   this->dynamic_section_ = this->make_output_section(dynamic_name,
 325                                                      elfcpp::SHT_DYNAMIC,
 326                                                      (elfcpp::SHF_ALLOC
 327                                                       | elfcpp::SHF_WRITE));
 328
 329   symtab->define_in_output_data(input_objects->target(), "_DYNAMIC", NULL,
 330                                 this->dynamic_section_, 0, 0,
 331                                 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
 332                                 elfcpp::STV_HIDDEN, 0, false, false);
 333
 334   this->dynamic_data_ =  new Output_data_dynamic(input_objects->target(),
 335                                                  &this->dynpool_);
 336
 337   this->dynamic_section_->add_output_section_data(this->dynamic_data_);
 338 }
 339
 340 // Find the first read-only PT_LOAD segment, creating one if
 341 // necessary.
 342
 343 Output_segment*
 344 Layout::find_first_load_seg()
 345 {
 346   for (Segment_list::const_iterator p = this->segment_list_.begin();
 347        p != this->segment_list_.end();
 348        ++p)
 349     {
 350       if ((*p)->type() == elfcpp::PT_LOAD
 351           && ((*p)->flags() & elfcpp::PF_R) != 0
 352           && ((*p)->flags() & elfcpp::PF_W) == 0)
 353         return *p;
 354     }
 355
 356   Output_segment* load_seg = new Output_segment(elfcpp::PT_LOAD, elfcpp::PF_R);
 357   this->segment_list_.push_back(load_seg);
 358   return load_seg;
 359 }
 360
 361 // Finalize the layout.  When this is called, we have created all the
 362 // output sections and all the output segments which are based on
 363 // input sections.  We have several things to do, and we have to do
 364 // them in the right order, so that we get the right results correctly
 365 // and efficiently.
 366
 367 // 1) Finalize the list of output segments and create the segment
 368 // table header.
 369
 370 // 2) Finalize the dynamic symbol table and associated sections.
 371
 372 // 3) Determine the final file offset of all the output segments.
 373
 374 // 4) Determine the final file offset of all the SHF_ALLOC output
 375 // sections.
 376
 377 // 5) Create the symbol table sections and the section name table
 378 // section.
 379
 380 // 6) Finalize the symbol table: set symbol values to their final
 381 // value and make a final determination of which symbols are going
 382 // into the output symbol table.
 383
 384 // 7) Create the section table header.
 385
 386 // 8) Determine the final file offset of all the output sections which
 387 // are not SHF_ALLOC, including the section table header.
 388
 389 // 9) Finalize the ELF file header.
 390
 391 // This function returns the size of the output file.
 392
 393 off_t
 394 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab)
 395 {
 396   Target* const target = input_objects->target();
 397   const int size = target->get_size();
 398
 399   target->finalize_sections(this);
 400
 401   Output_segment* phdr_seg = NULL;
 402   if (input_objects->any_dynamic())
 403     {
 404       // There was a dynamic object in the link.  We need to create
 405       // some information for the dynamic linker.
 406
 407       // Create the PT_PHDR segment which will hold the program
 408       // headers.
 409       phdr_seg = new Output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
 410       this->segment_list_.push_back(phdr_seg);
 411
 412       // Create the dynamic symbol table, including the hash table.
 413       Output_section* dynstr;
 414       std::vector<Symbol*> dynamic_symbols;
 415       unsigned int local_dynamic_count;
 416       Versions versions;
 417       this->create_dynamic_symtab(target, symtab, &dynstr,
 418                                   &local_dynamic_count, &dynamic_symbols,
 419                                   &versions);
 420
 421       // Create the .interp section to hold the name of the
 422       // interpreter, and put it in a PT_INTERP segment.
 423       this->create_interp(target);
 424
 425       // Finish the .dynamic section to hold the dynamic data, and put
 426       // it in a PT_DYNAMIC segment.
 427       this->finish_dynamic_section(input_objects, symtab);
 428
 429       // We should have added everything we need to the dynamic string
 430       // table.
 431       this->dynpool_.set_string_offsets();
 432
 433       // Create the version sections.  We can't do this until the
 434       // dynamic string table is complete.
 435       this->create_version_sections(target, &versions, local_dynamic_count,
 436                                     dynamic_symbols, dynstr);
 437     }
 438
 439   // FIXME: Handle PT_GNU_STACK.
 440
 441   Output_segment* load_seg = this->find_first_load_seg();
 442
 443   // Lay out the segment headers.
 444   bool big_endian = target->is_big_endian();
 445   Output_segment_headers* segment_headers;
 446   segment_headers = new Output_segment_headers(size, big_endian,
 447                                                this->segment_list_);
 448   load_seg->add_initial_output_data(segment_headers);
 449   this->special_output_list_.push_back(segment_headers);
 450   if (phdr_seg != NULL)
 451     phdr_seg->add_initial_output_data(segment_headers);
 452
 453   // Lay out the file header.
 454   Output_file_header* file_header;
 455   file_header = new Output_file_header(size,
 456                                        big_endian,
 457                                        target,
 458                                        symtab,
 459                                        segment_headers);
 460   load_seg->add_initial_output_data(file_header);
 461   this->special_output_list_.push_back(file_header);
 462
 463   // We set the output section indexes in set_segment_offsets and
 464   // set_section_offsets.
 465   unsigned int shndx = 1;
 466
 467   // Set the file offsets of all the segments, and all the sections
 468   // they contain.
 469   off_t off = this->set_segment_offsets(target, load_seg, &shndx);
 470
 471   // Create the symbol table sections.
 472   this->create_symtab_sections(size, input_objects, symtab, &off);
 473
 474   // Create the .shstrtab section.
 475   Output_section* shstrtab_section = this->create_shstrtab();
 476
 477   // Set the file offsets of all the sections not associated with
 478   // segments.
 479   off = this->set_section_offsets(off, &shndx);
 480
 481   // Create the section table header.
 482   Output_section_headers* oshdrs = this->create_shdrs(size, big_endian, &off);
 483
 484   file_header->set_section_info(oshdrs, shstrtab_section);
 485
 486   // Now we know exactly where everything goes in the output file.
 487   Output_data::layout_complete();
 488
 489   return off;
 490 }
 491
 492 // Return whether SEG1 should be before SEG2 in the output file.  This
 493 // is based entirely on the segment type and flags.  When this is
 494 // called the segment addresses has normally not yet been set.
 495
 496 bool
 497 Layout::segment_precedes(const Output_segment* seg1,
 498                          const Output_segment* seg2)
 499 {
 500   elfcpp::Elf_Word type1 = seg1->type();
 501   elfcpp::Elf_Word type2 = seg2->type();
 502
 503   // The single PT_PHDR segment is required to precede any loadable
 504   // segment.  We simply make it always first.
 505   if (type1 == elfcpp::PT_PHDR)
 506     {
 507       gold_assert(type2 != elfcpp::PT_PHDR);
 508       return true;
 509     }
 510   if (type2 == elfcpp::PT_PHDR)
 511     return false;
 512
 513   // The single PT_INTERP segment is required to precede any loadable
 514   // segment.  We simply make it always second.
 515   if (type1 == elfcpp::PT_INTERP)
 516     {
 517       gold_assert(type2 != elfcpp::PT_INTERP);
 518       return true;
 519     }
 520   if (type2 == elfcpp::PT_INTERP)
 521     return false;
 522
 523   // We then put PT_LOAD segments before any other segments.
 524   if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
 525     return true;
 526   if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
 527     return false;
 528
 529   // We put the PT_TLS segment last, because that is where the dynamic
 530   // linker expects to find it (this is just for efficiency; other
 531   // positions would also work correctly).
 532   if (type1 == elfcpp::PT_TLS && type2 != elfcpp::PT_TLS)
 533     return false;
 534   if (type2 == elfcpp::PT_TLS && type1 != elfcpp::PT_TLS)
 535     return true;
 536
 537   const elfcpp::Elf_Word flags1 = seg1->flags();
 538   const elfcpp::Elf_Word flags2 = seg2->flags();
 539
 540   // The order of non-PT_LOAD segments is unimportant.  We simply sort
 541   // by the numeric segment type and flags values.  There should not
 542   // be more than one segment with the same type and flags.
 543   if (type1 != elfcpp::PT_LOAD)
 544     {
 545       if (type1 != type2)
 546         return type1 < type2;
 547       gold_assert(flags1 != flags2);
 548       return flags1 < flags2;
 549     }
 550
 551   // We sort PT_LOAD segments based on the flags.  Readonly segments
 552   // come before writable segments.  Then executable segments come
 553   // before non-executable segments.  Then the unlikely case of a
 554   // non-readable segment comes before the normal case of a readable
 555   // segment.  If there are multiple segments with the same type and
 556   // flags, we require that the address be set, and we sort by
 557   // virtual address and then physical address.
 558   if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
 559     return (flags1 & elfcpp::PF_W) == 0;
 560   if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
 561     return (flags1 & elfcpp::PF_X) != 0;
 562   if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
 563     return (flags1 & elfcpp::PF_R) == 0;
 564
 565   uint64_t vaddr1 = seg1->vaddr();
 566   uint64_t vaddr2 = seg2->vaddr();
 567   if (vaddr1 != vaddr2)
 568     return vaddr1 < vaddr2;
 569
 570   uint64_t paddr1 = seg1->paddr();
 571   uint64_t paddr2 = seg2->paddr();
 572   gold_assert(paddr1 != paddr2);
 573   return paddr1 < paddr2;
 574 }
 575
 576 // Set the file offsets of all the segments, and all the sections they
 577 // contain.  They have all been created.  LOAD_SEG must be be laid out
 578 // first.  Return the offset of the data to follow.
 579
 580 off_t
 581 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
 582                             unsigned int *pshndx)
 583 {
 584   // Sort them into the final order.
 585   std::sort(this->segment_list_.begin(), this->segment_list_.end(),
 586             Layout::Compare_segments());
 587
 588   // Find the PT_LOAD segments, and set their addresses and offsets
 589   // and their section's addresses and offsets.
 590   uint64_t addr = target->text_segment_address();
 591   off_t off = 0;
 592   bool was_readonly = false;
 593   for (Segment_list::iterator p = this->segment_list_.begin();
 594        p != this->segment_list_.end();
 595        ++p)
 596     {
 597       if ((*p)->type() == elfcpp::PT_LOAD)
 598         {
 599           if (load_seg != NULL && load_seg != *p)
 600             gold_unreachable();
 601           load_seg = NULL;
 602
 603           // If the last segment was readonly, and this one is not,
 604           // then skip the address forward one page, maintaining the
 605           // same position within the page.  This lets us store both
 606           // segments overlapping on a single page in the file, but
 607           // the loader will put them on different pages in memory.
 608
 609           uint64_t orig_addr = addr;
 610           uint64_t orig_off = off;
 611
 612           uint64_t aligned_addr = addr;
 613           uint64_t abi_pagesize = target->abi_pagesize();
 614
 615           // FIXME: This should depend on the -n and -N options.
 616           (*p)->set_minimum_addralign(target->common_pagesize());
 617
 618           if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0)
 619             {
 620               uint64_t align = (*p)->addralign();
 621
 622               addr = align_address(addr, align);
 623               aligned_addr = addr;
 624               if ((addr & (abi_pagesize - 1)) != 0)
 625                 addr = addr + abi_pagesize;
 626             }
 627
 628           unsigned int shndx_hold = *pshndx;
 629           off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
 630           uint64_t new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
 631
 632           // Now that we know the size of this segment, we may be able
 633           // to save a page in memory, at the cost of wasting some
 634           // file space, by instead aligning to the start of a new
 635           // page.  Here we use the real machine page size rather than
 636           // the ABI mandated page size.
 637
 638           if (aligned_addr != addr)
 639             {
 640               uint64_t common_pagesize = target->common_pagesize();
 641               uint64_t first_off = (common_pagesize
 642                                     - (aligned_addr
 643                                        & (common_pagesize - 1)));
 644               uint64_t last_off = new_addr & (common_pagesize - 1);
 645               if (first_off > 0
 646                   && last_off > 0
 647                   && ((aligned_addr & ~ (common_pagesize - 1))
 648                       != (new_addr & ~ (common_pagesize - 1)))
 649                   && first_off + last_off <= common_pagesize)
 650                 {
 651                   *pshndx = shndx_hold;
 652                   addr = align_address(aligned_addr, common_pagesize);
 653                   off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
 654                   new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
 655                 }
 656             }
 657
 658           addr = new_addr;
 659
 660           if (((*p)->flags() & elfcpp::PF_W) == 0)
 661             was_readonly = true;
 662         }
 663     }
 664
 665   // Handle the non-PT_LOAD segments, setting their offsets from their
 666   // section's offsets.
 667   for (Segment_list::iterator p = this->segment_list_.begin();
 668        p != this->segment_list_.end();
 669        ++p)
 670     {
 671       if ((*p)->type() != elfcpp::PT_LOAD)
 672         (*p)->set_offset();
 673     }
 674
 675   return off;
 676 }
 677
 678 // Set the file offset of all the sections not associated with a
 679 // segment.
 680
 681 off_t
 682 Layout::set_section_offsets(off_t off, unsigned int* pshndx)
 683 {
 684   for (Section_list::iterator p = this->unattached_section_list_.begin();
 685        p != this->unattached_section_list_.end();
 686        ++p)
 687     {
 688       (*p)->set_out_shndx(*pshndx);
 689       ++*pshndx;
 690       if ((*p)->offset() != -1)
 691         continue;
 692       off = align_address(off, (*p)->addralign());
 693       (*p)->set_address(0, off);
 694       off += (*p)->data_size();
 695     }
 696   return off;
 697 }
 698
 699 // Create the symbol table sections.  Here we also set the final
 700 // values of the symbols.  At this point all the loadable sections are
 701 // fully laid out.
 702
 703 void
 704 Layout::create_symtab_sections(int size, const Input_objects* input_objects,
 705                                Symbol_table* symtab,
 706                                off_t* poff)
 707 {
 708   int symsize;
 709   unsigned int align;
 710   if (size == 32)
 711     {
 712       symsize = elfcpp::Elf_sizes<32>::sym_size;
 713       align = 4;
 714     }
 715   else if (size == 64)
 716     {
 717       symsize = elfcpp::Elf_sizes<64>::sym_size;
 718       align = 8;
 719     }
 720   else
 721     gold_unreachable();
 722
 723   off_t off = *poff;
 724   off = align_address(off, align);
 725   off_t startoff = off;
 726
 727   // Save space for the dummy symbol at the start of the section.  We
 728   // never bother to write this out--it will just be left as zero.
 729   off += symsize;
 730   unsigned int local_symbol_index = 1;
 731
 732   // Add STT_SECTION symbols for each Output section which needs one.
 733   for (Section_list::iterator p = this->section_list_.begin();
 734        p != this->section_list_.end();
 735        ++p)
 736     {
 737       if (!(*p)->needs_symtab_index())
 738         (*p)->set_symtab_index(-1U);
 739       else
 740         {
 741           (*p)->set_symtab_index(local_symbol_index);
 742           ++local_symbol_index;
 743           off += symsize;
 744         }
 745     }
 746
 747   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
 748        p != input_objects->relobj_end();
 749        ++p)
 750     {
 751       Task_lock_obj<Object> tlo(**p);
 752       unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
 753                                                         off,
 754                                                         &this->sympool_);
 755       off += (index - local_symbol_index) * symsize;
 756       local_symbol_index = index;
 757     }
 758
 759   unsigned int local_symcount = local_symbol_index;
 760   gold_assert(local_symcount * symsize == off - startoff);
 761
 762   off_t dynoff;
 763   size_t dyn_global_index;
 764   size_t dyncount;
 765   if (this->dynsym_section_ == NULL)
 766     {
 767       dynoff = 0;
 768       dyn_global_index = 0;
 769       dyncount = 0;
 770     }
 771   else
 772     {
 773       dyn_global_index = this->dynsym_section_->info();
 774       off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
 775       dynoff = this->dynsym_section_->offset() + locsize;
 776       dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
 777       gold_assert(dyncount * symsize
 778                   == this->dynsym_section_->data_size() - locsize);
 779     }
 780
 781   off = symtab->finalize(local_symcount, off, dynoff, dyn_global_index,
 782                          dyncount, &this->sympool_);
 783
 784   this->sympool_.set_string_offsets();
 785
 786   const char* symtab_name = this->namepool_.add(".symtab", NULL);
 787   Output_section* osymtab = this->make_output_section(symtab_name,
 788                                                       elfcpp::SHT_SYMTAB,
 789                                                       0);
 790   this->symtab_section_ = osymtab;
 791
 792   Output_section_data* pos = new Output_data_space(off - startoff,
 793                                                    align);
 794   osymtab->add_output_section_data(pos);
 795
 796   const char* strtab_name = this->namepool_.add(".strtab", NULL);
 797   Output_section* ostrtab = this->make_output_section(strtab_name,
 798                                                       elfcpp::SHT_STRTAB,
 799                                                       0);
 800
 801   Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
 802   ostrtab->add_output_section_data(pstr);
 803
 804   osymtab->set_address(0, startoff);
 805   osymtab->set_link_section(ostrtab);
 806   osymtab->set_info(local_symcount);
 807   osymtab->set_entsize(symsize);
 808
 809   *poff = off;
 810 }
 811
 812 // Create the .shstrtab section, which holds the names of the
 813 // sections.  At the time this is called, we have created all the
 814 // output sections except .shstrtab itself.
 815
 816 Output_section*
 817 Layout::create_shstrtab()
 818 {
 819   // FIXME: We don't need to create a .shstrtab section if we are
 820   // stripping everything.
 821
 822   const char* name = this->namepool_.add(".shstrtab", NULL);
 823
 824   this->namepool_.set_string_offsets();
 825
 826   Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0);
 827
 828   Output_section_data* posd = new Output_data_strtab(&this->namepool_);
 829   os->add_output_section_data(posd);
 830
 831   return os;
 832 }
 833
 834 // Create the section headers.  SIZE is 32 or 64.  OFF is the file
 835 // offset.
 836
 837 Output_section_headers*
 838 Layout::create_shdrs(int size, bool big_endian, off_t* poff)
 839 {
 840   Output_section_headers* oshdrs;
 841   oshdrs = new Output_section_headers(size, big_endian, this,
 842                                       &this->segment_list_,
 843                                       &this->unattached_section_list_,
 844                                       &this->namepool_);
 845   off_t off = align_address(*poff, oshdrs->addralign());
 846   oshdrs->set_address(0, off);
 847   off += oshdrs->data_size();
 848   *poff = off;
 849   this->special_output_list_.push_back(oshdrs);
 850   return oshdrs;
 851 }
 852
 853 // Create the dynamic symbol table.
 854
 855 void
 856 Layout::create_dynamic_symtab(const Target* target, Symbol_table* symtab,
 857                               Output_section **pdynstr,
 858                               unsigned int* plocal_dynamic_count,
 859                               std::vector<Symbol*>* pdynamic_symbols,
 860                               Versions* pversions)
 861 {
 862   // Count all the symbols in the dynamic symbol table, and set the
 863   // dynamic symbol indexes.
 864
 865   // Skip symbol 0, which is always all zeroes.
 866   unsigned int index = 1;
 867
 868   // Add STT_SECTION symbols for each Output section which needs one.
 869   for (Section_list::iterator p = this->section_list_.begin();
 870        p != this->section_list_.end();
 871        ++p)
 872     {
 873       if (!(*p)->needs_dynsym_index())
 874         (*p)->set_dynsym_index(-1U);
 875       else
 876         {
 877           (*p)->set_dynsym_index(index);
 878           ++index;
 879         }
 880     }
 881
 882   // FIXME: Some targets apparently require local symbols in the
 883   // dynamic symbol table.  Here is where we will have to count them,
 884   // and set the dynamic symbol indexes, and add the names to
 885   // this->dynpool_.
 886
 887   unsigned int local_symcount = index;
 888   *plocal_dynamic_count = local_symcount;
 889
 890   // FIXME: We have to tell set_dynsym_indexes whether the
 891   // -E/--export-dynamic option was used.
 892   index = symtab->set_dynsym_indexes(&this->options_, target, index,
 893                                      pdynamic_symbols, &this->dynpool_,
 894                                      pversions);
 895
 896   int symsize;
 897   unsigned int align;
 898   const int size = target->get_size();
 899   if (size == 32)
 900     {
 901       symsize = elfcpp::Elf_sizes<32>::sym_size;
 902       align = 4;
 903     }
 904   else if (size == 64)
 905     {
 906       symsize = elfcpp::Elf_sizes<64>::sym_size;
 907       align = 8;
 908     }
 909   else
 910     gold_unreachable();
 911
 912   // Create the dynamic symbol table section.
 913
 914   const char* dynsym_name = this->namepool_.add(".dynsym", NULL);
 915   Output_section* dynsym = this->make_output_section(dynsym_name,
 916                                                      elfcpp::SHT_DYNSYM,
 917                                                      elfcpp::SHF_ALLOC);
 918
 919   Output_section_data* odata = new Output_data_space(index * symsize,
 920                                                      align);
 921   dynsym->add_output_section_data(odata);
 922
 923   dynsym->set_info(local_symcount);
 924   dynsym->set_entsize(symsize);
 925   dynsym->set_addralign(align);
 926
 927   this->dynsym_section_ = dynsym;
 928
 929   Output_data_dynamic* const odyn = this->dynamic_data_;
 930   odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
 931   odyn->add_constant(elfcpp::DT_SYMENT, symsize);
 932
 933   // Create the dynamic string table section.
 934
 935   const char* dynstr_name = this->namepool_.add(".dynstr", NULL);
 936   Output_section* dynstr = this->make_output_section(dynstr_name,
 937                                                      elfcpp::SHT_STRTAB,
 938                                                      elfcpp::SHF_ALLOC);
 939
 940   Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
 941   dynstr->add_output_section_data(strdata);
 942
 943   dynsym->set_link_section(dynstr);
 944   this->dynamic_section_->set_link_section(dynstr);
 945
 946   odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
 947   odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
 948
 949   *pdynstr = dynstr;
 950
 951   // Create the hash tables.
 952
 953   // FIXME: We need an option to create a GNU hash table.
 954
 955   unsigned char* phash;
 956   unsigned int hashlen;
 957   Dynobj::create_elf_hash_table(target, *pdynamic_symbols, local_symcount,
 958                                 &phash, &hashlen);
 959
 960   const char* hash_name = this->namepool_.add(".hash", NULL);
 961   Output_section* hashsec = this->make_output_section(hash_name,
 962                                                       elfcpp::SHT_HASH,
 963                                                       elfcpp::SHF_ALLOC);
 964
 965   Output_section_data* hashdata = new Output_data_const_buffer(phash,
 966                                                                hashlen,
 967                                                                align);
 968   hashsec->add_output_section_data(hashdata);
 969
 970   hashsec->set_link_section(dynsym);
 971   hashsec->set_entsize(4);
 972
 973   odyn->add_section_address(elfcpp::DT_HASH, hashsec);
 974 }
 975
 976 // Create the version sections.
 977
 978 void
 979 Layout::create_version_sections(const Target* target, const Versions* versions,
 980                                 unsigned int local_symcount,
 981                                 const std::vector<Symbol*>& dynamic_symbols,
 982                                 const Output_section* dynstr)
 983 {
 984   if (!versions->any_defs() && !versions->any_needs())
 985     return;
 986
 987   if (target->get_size() == 32)
 988     {
 989       if (target->is_big_endian())
 990         {
 991 #ifdef HAVE_TARGET_32_BIG
 992           this->sized_create_version_sections
 993               SELECT_SIZE_ENDIAN_NAME(32, true)(
 994                   versions, local_symcount, dynamic_symbols, dynstr
 995                   SELECT_SIZE_ENDIAN(32, true));
 996 #else
 997           gold_unreachable();
 998 #endif
 999         }
1000       else
1001         {
1002 #ifdef HAVE_TARGET_32_LITTLE
1003           this->sized_create_version_sections
1004               SELECT_SIZE_ENDIAN_NAME(32, false)(
1005                   versions, local_symcount, dynamic_symbols, dynstr
1006                   SELECT_SIZE_ENDIAN(32, false));
1007 #else
1008           gold_unreachable();
1009 #endif
1010         }
1011     }
1012   else if (target->get_size() == 64)
1013     {
1014       if (target->is_big_endian())
1015         {
1016 #ifdef HAVE_TARGET_64_BIG
1017           this->sized_create_version_sections
1018               SELECT_SIZE_ENDIAN_NAME(64, true)(
1019                   versions, local_symcount, dynamic_symbols, dynstr
1020                   SELECT_SIZE_ENDIAN(64, true));
1021 #else
1022           gold_unreachable();
1023 #endif
1024         }
1025       else
1026         {
1027 #ifdef HAVE_TARGET_64_LITTLE
1028           this->sized_create_version_sections
1029               SELECT_SIZE_ENDIAN_NAME(64, false)(
1030                   versions, local_symcount, dynamic_symbols, dynstr
1031                   SELECT_SIZE_ENDIAN(64, false));
1032 #else
1033           gold_unreachable();
1034 #endif
1035         }
1036     }
1037   else
1038     gold_unreachable();
1039 }
1040
1041 // Create the version sections, sized version.
1042
1043 template<int size, bool big_endian>
1044 void
1045 Layout::sized_create_version_sections(
1046     const Versions* versions,
1047     unsigned int local_symcount,
1048     const std::vector<Symbol*>& dynamic_symbols,
1049     const Output_section* dynstr
1050     ACCEPT_SIZE_ENDIAN)
1051 {
1052   const char* vname = this->namepool_.add(".gnu.version", NULL);
1053   Output_section* vsec = this->make_output_section(vname,
1054                                                    elfcpp::SHT_GNU_versym,
1055                                                    elfcpp::SHF_ALLOC);
1056
1057   unsigned char* vbuf;
1058   unsigned int vsize;
1059   versions->symbol_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)(
1060       &this->dynpool_, local_symcount, dynamic_symbols, &vbuf, &vsize
1061       SELECT_SIZE_ENDIAN(size, big_endian));
1062
1063   Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2);
1064
1065   vsec->add_output_section_data(vdata);
1066   vsec->set_entsize(2);
1067   vsec->set_link_section(this->dynsym_section_);
1068
1069   Output_data_dynamic* const odyn = this->dynamic_data_;
1070   odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
1071
1072   if (versions->any_defs())
1073     {
1074       const char* vdname = this->namepool_.add(".gnu.version_d", NULL);
1075       Output_section *vdsec;
1076       vdsec = this->make_output_section(vdname, elfcpp::SHT_GNU_verdef,
1077                                         elfcpp::SHF_ALLOC);
1078
1079       unsigned char* vdbuf;
1080       unsigned int vdsize;
1081       unsigned int vdentries;
1082       versions->def_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)(
1083           &this->dynpool_, &vdbuf, &vdsize, &vdentries
1084           SELECT_SIZE_ENDIAN(size, big_endian));
1085
1086       Output_section_data* vddata = new Output_data_const_buffer(vdbuf,
1087                                                                  vdsize,
1088                                                                  4);
1089
1090       vdsec->add_output_section_data(vddata);
1091       vdsec->set_link_section(dynstr);
1092       vdsec->set_info(vdentries);
1093
1094       odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
1095       odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
1096     }
1097
1098   if (versions->any_needs())
1099     {
1100       const char* vnname = this->namepool_.add(".gnu.version_r", NULL);
1101       Output_section* vnsec;
1102       vnsec = this->make_output_section(vnname, elfcpp::SHT_GNU_verneed,
1103                                         elfcpp::SHF_ALLOC);
1104
1105       unsigned char* vnbuf;
1106       unsigned int vnsize;
1107       unsigned int vnentries;
1108       versions->need_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)
1109         (&this->dynpool_, &vnbuf, &vnsize, &vnentries
1110          SELECT_SIZE_ENDIAN(size, big_endian));
1111
1112       Output_section_data* vndata = new Output_data_const_buffer(vnbuf,
1113                                                                  vnsize,
1114                                                                  4);
1115
1116       vnsec->add_output_section_data(vndata);
1117       vnsec->set_link_section(dynstr);
1118       vnsec->set_info(vnentries);
1119
1120       odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
1121       odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
1122     }
1123 }
1124
1125 // Create the .interp section and PT_INTERP segment.
1126
1127 void
1128 Layout::create_interp(const Target* target)
1129 {
1130   const char* interp = this->options_.dynamic_linker();
1131   if (interp == NULL)
1132     {
1133       interp = target->dynamic_linker();
1134       gold_assert(interp != NULL);
1135     }
1136
1137   size_t len = strlen(interp) + 1;
1138
1139   Output_section_data* odata = new Output_data_const(interp, len, 1);
1140
1141   const char* interp_name = this->namepool_.add(".interp", NULL);
1142   Output_section* osec = this->make_output_section(interp_name,
1143                                                    elfcpp::SHT_PROGBITS,
1144                                                    elfcpp::SHF_ALLOC);
1145   osec->add_output_section_data(odata);
1146
1147   Output_segment* oseg = new Output_segment(elfcpp::PT_INTERP, elfcpp::PF_R);
1148   this->segment_list_.push_back(oseg);
1149   oseg->add_initial_output_section(osec, elfcpp::PF_R);
1150 }
1151
1152 // Finish the .dynamic section and PT_DYNAMIC segment.
1153
1154 void
1155 Layout::finish_dynamic_section(const Input_objects* input_objects,
1156                                const Symbol_table* symtab)
1157 {
1158   Output_segment* oseg = new Output_segment(elfcpp::PT_DYNAMIC,
1159                                             elfcpp::PF_R | elfcpp::PF_W);
1160   this->segment_list_.push_back(oseg);
1161   oseg->add_initial_output_section(this->dynamic_section_,
1162                                    elfcpp::PF_R | elfcpp::PF_W);
1163
1164   Output_data_dynamic* const odyn = this->dynamic_data_;
1165
1166   for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
1167        p != input_objects->dynobj_end();
1168        ++p)
1169     {
1170       // FIXME: Handle --as-needed.
1171       odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
1172     }
1173
1174   // FIXME: Support --init and --fini.
1175   Symbol* sym = symtab->lookup("_init");
1176   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
1177     odyn->add_symbol(elfcpp::DT_INIT, sym);
1178
1179   sym = symtab->lookup("_fini");
1180   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
1181     odyn->add_symbol(elfcpp::DT_FINI, sym);
1182
1183   // FIXME: Support DT_INIT_ARRAY and DT_FINI_ARRAY.
1184
1185   // Add a DT_RPATH entry if needed.
1186   const General_options::Dir_list& rpath(this->options_.rpath());
1187   if (!rpath.empty())
1188     {
1189       std::string rpath_val;
1190       for (General_options::Dir_list::const_iterator p = rpath.begin();
1191            p != rpath.end();
1192            ++p)
1193         {
1194           if (rpath_val.empty())
1195             rpath_val = *p;
1196           else
1197             {
1198               // Eliminate duplicates.
1199               General_options::Dir_list::const_iterator q;
1200               for (q = rpath.begin(); q != p; ++q)
1201                 if (strcmp(*q, *p) == 0)
1202                   break;
1203               if (q == p)
1204                 {
1205                   rpath_val += ':';
1206                   rpath_val += *p;
1207                 }
1208             }
1209         }
1210
1211       odyn->add_string(elfcpp::DT_RPATH, rpath_val);
1212     }
1213 }
1214
1215 // The mapping of .gnu.linkonce section names to real section names.
1216
1217 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
1218 const Layout::Linkonce_mapping Layout::linkonce_mapping[] =
1219 {
1220   MAPPING_INIT("d.rel.ro", ".data.rel.ro"),     // Must be before "d".
1221   MAPPING_INIT("t", ".text"),
1222   MAPPING_INIT("r", ".rodata"),
1223   MAPPING_INIT("d", ".data"),
1224   MAPPING_INIT("b", ".bss"),
1225   MAPPING_INIT("s", ".sdata"),
1226   MAPPING_INIT("sb", ".sbss"),
1227   MAPPING_INIT("s2", ".sdata2"),
1228   MAPPING_INIT("sb2", ".sbss2"),
1229   MAPPING_INIT("wi", ".debug_info"),
1230   MAPPING_INIT("td", ".tdata"),
1231   MAPPING_INIT("tb", ".tbss"),
1232   MAPPING_INIT("lr", ".lrodata"),
1233   MAPPING_INIT("l", ".ldata"),
1234   MAPPING_INIT("lb", ".lbss"),
1235 };
1236 #undef MAPPING_INIT
1237
1238 const int Layout::linkonce_mapping_count =
1239   sizeof(Layout::linkonce_mapping) / sizeof(Layout::linkonce_mapping[0]);
1240
1241 // Return the name of the output section to use for a .gnu.linkonce
1242 // section.  This is based on the default ELF linker script of the old
1243 // GNU linker.  For example, we map a name like ".gnu.linkonce.t.foo"
1244 // to ".text".  Set *PLEN to the length of the name.  *PLEN is
1245 // initialized to the length of NAME.
1246
1247 const char*
1248 Layout::linkonce_output_name(const char* name, size_t *plen)
1249 {
1250   const char* s = name + sizeof(".gnu.linkonce") - 1;
1251   if (*s != '.')
1252     return name;
1253   ++s;
1254   const Linkonce_mapping* plm = linkonce_mapping;
1255   for (int i = 0; i < linkonce_mapping_count; ++i, ++plm)
1256     {
1257       if (strncmp(s, plm->from, plm->fromlen) == 0 && s[plm->fromlen] == '.')
1258         {
1259           *plen = plm->tolen;
1260           return plm->to;
1261         }
1262     }
1263   return name;
1264 }
1265
1266 // Choose the output section name to use given an input section name.
1267 // Set *PLEN to the length of the name.  *PLEN is initialized to the
1268 // length of NAME.
1269
1270 const char*
1271 Layout::output_section_name(const char* name, size_t* plen)
1272 {
1273   if (Layout::is_linkonce(name))
1274     {
1275       // .gnu.linkonce sections are laid out as though they were named
1276       // for the sections are placed into.
1277       return Layout::linkonce_output_name(name, plen);
1278     }
1279
1280   // If the section name has no '.', or only an initial '.', we use
1281   // the name unchanged (i.e., ".text" is unchanged).
1282
1283   // Otherwise, if the section name does not include ".rel", we drop
1284   // the last '.'  and everything that follows (i.e., ".text.XXX"
1285   // becomes ".text").
1286
1287   // Otherwise, if the section name has zero or one '.' after the
1288   // ".rel", we use the name unchanged (i.e., ".rel.text" is
1289   // unchanged).
1290
1291   // Otherwise, we drop the last '.' and everything that follows
1292   // (i.e., ".rel.text.XXX" becomes ".rel.text").
1293
1294   const char* s = name;
1295   if (*s == '.')
1296     ++s;
1297   const char* sdot = strchr(s, '.');
1298   if (sdot == NULL)
1299     return name;
1300
1301   const char* srel = strstr(s, ".rel");
1302   if (srel == NULL)
1303     {
1304       *plen = sdot - name;
1305       return name;
1306     }
1307
1308   sdot = strchr(srel + 1, '.');
1309   if (sdot == NULL)
1310     return name;
1311   sdot = strchr(sdot + 1, '.');
1312   if (sdot == NULL)
1313     return name;
1314
1315   *plen = sdot - name;
1316   return name;
1317 }
1318
1319 // Record the signature of a comdat section, and return whether to
1320 // include it in the link.  If GROUP is true, this is a regular
1321 // section group.  If GROUP is false, this is a group signature
1322 // derived from the name of a linkonce section.  We want linkonce
1323 // signatures and group signatures to block each other, but we don't
1324 // want a linkonce signature to block another linkonce signature.
1325
1326 bool
1327 Layout::add_comdat(const char* signature, bool group)
1328 {
1329   std::string sig(signature);
1330   std::pair<Signatures::iterator, bool> ins(
1331     this->signatures_.insert(std::make_pair(sig, group)));
1332
1333   if (ins.second)
1334     {
1335       // This is the first time we've seen this signature.
1336       return true;
1337     }
1338
1339   if (ins.first->second)
1340     {
1341       // We've already seen a real section group with this signature.
1342       return false;
1343     }
1344   else if (group)
1345     {
1346       // This is a real section group, and we've already seen a
1347       // linkonce section with tihs signature.  Record that we've seen
1348       // a section group, and don't include this section group.
1349       ins.first->second = true;
1350       return false;
1351     }
1352   else
1353     {
1354       // We've already seen a linkonce section and this is a linkonce
1355       // section.  These don't block each other--this may be the same
1356       // symbol name with different section types.
1357       return true;
1358     }
1359 }
1360
1361 // Write out data not associated with a section or the symbol table.
1362
1363 void
1364 Layout::write_data(const Symbol_table* symtab, const Target* target,
1365                    Output_file* of) const
1366 {
1367   const Output_section* symtab_section = this->symtab_section_;
1368   for (Section_list::const_iterator p = this->section_list_.begin();
1369        p != this->section_list_.end();
1370        ++p)
1371     {
1372       if ((*p)->needs_symtab_index())
1373         {
1374           gold_assert(symtab_section != NULL);
1375           unsigned int index = (*p)->symtab_index();
1376           gold_assert(index > 0 && index != -1U);
1377           off_t off = (symtab_section->offset()
1378                        + index * symtab_section->entsize());
1379           symtab->write_section_symbol(target, *p, of, off);
1380         }
1381     }
1382
1383   const Output_section* dynsym_section = this->dynsym_section_;
1384   for (Section_list::const_iterator p = this->section_list_.begin();
1385        p != this->section_list_.end();
1386        ++p)
1387     {
1388       if ((*p)->needs_dynsym_index())
1389         {
1390           gold_assert(dynsym_section != NULL);
1391           unsigned int index = (*p)->dynsym_index();
1392           gold_assert(index > 0 && index != -1U);
1393           off_t off = (dynsym_section->offset()
1394                        + index * dynsym_section->entsize());
1395           symtab->write_section_symbol(target, *p, of, off);
1396         }
1397     }
1398
1399   // Write out the Output_sections.  Most won't have anything to
1400   // write, since most of the data will come from input sections which
1401   // are handled elsewhere.  But some Output_sections do have
1402   // Output_data.
1403   for (Section_list::const_iterator p = this->section_list_.begin();
1404        p != this->section_list_.end();
1405        ++p)
1406     (*p)->write(of);
1407
1408   // Write out the Output_data which are not in an Output_section.
1409   for (Data_list::const_iterator p = this->special_output_list_.begin();
1410        p != this->special_output_list_.end();
1411        ++p)
1412     (*p)->write(of);
1413 }
1414
1415 // Write_data_task methods.
1416
1417 // We can always run this task.
1418
1419 Task::Is_runnable_type
1420 Write_data_task::is_runnable(Workqueue*)
1421 {
1422   return IS_RUNNABLE;
1423 }
1424
1425 // We need to unlock FINAL_BLOCKER when finished.
1426
1427 Task_locker*
1428 Write_data_task::locks(Workqueue* workqueue)
1429 {
1430   return new Task_locker_block(*this->final_blocker_, workqueue);
1431 }
1432
1433 // Run the task--write out the data.
1434
1435 void
1436 Write_data_task::run(Workqueue*)
1437 {
1438   this->layout_->write_data(this->symtab_, this->target_, this->of_);
1439 }
1440
1441 // Write_symbols_task methods.
1442
1443 // We can always run this task.
1444
1445 Task::Is_runnable_type
1446 Write_symbols_task::is_runnable(Workqueue*)
1447 {
1448   return IS_RUNNABLE;
1449 }
1450
1451 // We need to unlock FINAL_BLOCKER when finished.
1452
1453 Task_locker*
1454 Write_symbols_task::locks(Workqueue* workqueue)
1455 {
1456   return new Task_locker_block(*this->final_blocker_, workqueue);
1457 }
1458
1459 // Run the task--write out the symbols.
1460
1461 void
1462 Write_symbols_task::run(Workqueue*)
1463 {
1464   this->symtab_->write_globals(this->target_, this->sympool_, this->dynpool_,
1465                                this->of_);
1466 }
1467
1468 // Close_task_runner methods.
1469
1470 // Run the task--close the file.
1471
1472 void
1473 Close_task_runner::run(Workqueue*)
1474 {
1475   this->of_->close();
1476 }
1477
1478 // Instantiate the templates we need.  We could use the configure
1479 // script to restrict this to only the ones for implemented targets.
1480
1481 #ifdef HAVE_TARGET_32_LITTLE
1482 template
1483 Output_section*
1484 Layout::layout<32, false>(Relobj* object, unsigned int shndx, const char* name,
1485                           const elfcpp::Shdr<32, false>& shdr, off_t*);
1486 #endif
1487
1488 #ifdef HAVE_TARGET_32_BIG
1489 template
1490 Output_section*
1491 Layout::layout<32, true>(Relobj* object, unsigned int shndx, const char* name,
1492                          const elfcpp::Shdr<32, true>& shdr, off_t*);
1493 #endif
1494
1495 #ifdef HAVE_TARGET_64_LITTLE
1496 template
1497 Output_section*
1498 Layout::layout<64, false>(Relobj* object, unsigned int shndx, const char* name,
1499                           const elfcpp::Shdr<64, false>& shdr, off_t*);
1500 #endif
1501
1502 #ifdef HAVE_TARGET_64_BIG
1503 template
1504 Output_section*
1505 Layout::layout<64, true>(Relobj* object, unsigned int shndx, const char* name,
1506                          const elfcpp::Shdr<64, true>& shdr, off_t*);
1507 #endif
1508
1509
1510 } // End namespace gold.