gold/layout.cc

   1 // layout.cc -- lay out output file sections for gold
   2
   3 // Copyright 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #include "gold.h"
  24
  25 #include <cerrno>
  26 #include <cstring>
  27 #include <algorithm>
  28 #include <iostream>
  29 #include <utility>
  30 #include <fcntl.h>
  31 #include <unistd.h>
  32 #include "libiberty.h"
  33 #include "md5.h"
  34 #include "sha1.h"
  35
  36 #include "parameters.h"
  37 #include "options.h"
  38 #include "mapfile.h"
  39 #include "script.h"
  40 #include "script-sections.h"
  41 #include "output.h"
  42 #include "symtab.h"
  43 #include "dynobj.h"
  44 #include "ehframe.h"
  45 #include "compressed_output.h"
  46 #include "reduced_debug_output.h"
  47 #include "reloc.h"
  48 #include "descriptors.h"
  49 #include "plugin.h"
  50 #include "incremental.h"
  51 #include "layout.h"
  52
  53 namespace gold
  54 {
  55
  56 // Layout::Relaxation_debug_check methods.
  57
  58 // Check that sections and special data are in reset states.
  59 // We do not save states for Output_sections and special Output_data.
  60 // So we check that they have not assigned any addresses or offsets.
  61 // clean_up_after_relaxation simply resets their addresses and offsets.
  62 void
  63 Layout::Relaxation_debug_check::check_output_data_for_reset_values(
  64     const Layout::Section_list& sections,
  65     const Layout::Data_list& special_outputs)
  66 {
  67   for(Layout::Section_list::const_iterator p = sections.begin();
  68       p != sections.end();
  69       ++p)
  70     gold_assert((*p)->address_and_file_offset_have_reset_values());
  71
  72   for(Layout::Data_list::const_iterator p = special_outputs.begin();
  73       p != special_outputs.end();
  74       ++p)
  75     gold_assert((*p)->address_and_file_offset_have_reset_values());
  76 }
  77
  78 // Save information of SECTIONS for checking later.
  79
  80 void
  81 Layout::Relaxation_debug_check::read_sections(
  82     const Layout::Section_list& sections)
  83 {
  84   for(Layout::Section_list::const_iterator p = sections.begin();
  85       p != sections.end();
  86       ++p)
  87     {
  88       Output_section* os = *p;
  89       Section_info info;
  90       info.output_section = os;
  91       info.address = os->is_address_valid() ? os->address() : 0;
  92       info.data_size = os->is_data_size_valid() ? os->data_size() : -1;
  93       info.offset = os->is_offset_valid()? os->offset() : -1 ;
  94       this->section_infos_.push_back(info);
  95     }
  96 }
  97
  98 // Verify SECTIONS using previously recorded information.
  99
 100 void
 101 Layout::Relaxation_debug_check::verify_sections(
 102     const Layout::Section_list& sections)
 103 {
 104   size_t i = 0;
 105   for(Layout::Section_list::const_iterator p = sections.begin();
 106       p != sections.end();
 107       ++p, ++i)
 108     {
 109       Output_section* os = *p;
 110       uint64_t address = os->is_address_valid() ? os->address() : 0;
 111       off_t data_size = os->is_data_size_valid() ? os->data_size() : -1;
 112       off_t offset = os->is_offset_valid()? os->offset() : -1 ;
 113
 114       if (i >= this->section_infos_.size())
 115         {
 116           gold_fatal("Section_info of %s missing.\n", os->name());
 117         }
 118       const Section_info& info = this->section_infos_[i];
 119       if (os != info.output_section)
 120         gold_fatal("Section order changed.  Expecting %s but see %s\n",
 121                    info.output_section->name(), os->name());
 122       if (address != info.address
 123           || data_size != info.data_size
 124           || offset != info.offset)
 125         gold_fatal("Section %s changed.\n", os->name());
 126     }
 127 }
 128
 129 // Layout_task_runner methods.
 130
 131 // Lay out the sections.  This is called after all the input objects
 132 // have been read.
 133
 134 void
 135 Layout_task_runner::run(Workqueue* workqueue, const Task* task)
 136 {
 137   off_t file_size = this->layout_->finalize(this->input_objects_,
 138                                             this->symtab_,
 139                                             this->target_,
 140                                             task);
 141
 142   // Now we know the final size of the output file and we know where
 143   // each piece of information goes.
 144
 145   if (this->mapfile_ != NULL)
 146     {
 147       this->mapfile_->print_discarded_sections(this->input_objects_);
 148       this->layout_->print_to_mapfile(this->mapfile_);
 149     }
 150
 151   Output_file* of = new Output_file(parameters->options().output_file_name());
 152   if (this->options_.oformat_enum() != General_options::OBJECT_FORMAT_ELF)
 153     of->set_is_temporary();
 154   of->open(file_size);
 155
 156   // Queue up the final set of tasks.
 157   gold::queue_final_tasks(this->options_, this->input_objects_,
 158                           this->symtab_, this->layout_, workqueue, of);
 159 }
 160
 161 // Layout methods.
 162
 163 Layout::Layout(int number_of_input_files, Script_options* script_options)
 164   : number_of_input_files_(number_of_input_files),
 165     script_options_(script_options),
 166     namepool_(),
 167     sympool_(),
 168     dynpool_(),
 169     signatures_(),
 170     section_name_map_(),
 171     segment_list_(),
 172     section_list_(),
 173     unattached_section_list_(),
 174     special_output_list_(),
 175     section_headers_(NULL),
 176     tls_segment_(NULL),
 177     relro_segment_(NULL),
 178     increase_relro_(0),
 179     symtab_section_(NULL),
 180     symtab_xindex_(NULL),
 181     dynsym_section_(NULL),
 182     dynsym_xindex_(NULL),
 183     dynamic_section_(NULL),
 184     dynamic_symbol_(NULL),
 185     dynamic_data_(NULL),
 186     eh_frame_section_(NULL),
 187     eh_frame_data_(NULL),
 188     added_eh_frame_data_(false),
 189     eh_frame_hdr_section_(NULL),
 190     build_id_note_(NULL),
 191     debug_abbrev_(NULL),
 192     debug_info_(NULL),
 193     group_signatures_(),
 194     output_file_size_(-1),
 195     have_added_input_section_(false),
 196     sections_are_attached_(false),
 197     input_requires_executable_stack_(false),
 198     input_with_gnu_stack_note_(false),
 199     input_without_gnu_stack_note_(false),
 200     has_static_tls_(false),
 201     any_postprocessing_sections_(false),
 202     resized_signatures_(false),
 203     have_stabstr_section_(false),
 204     incremental_inputs_(NULL),
 205     record_output_section_data_from_script_(false),
 206     script_output_section_data_list_(),
 207     segment_states_(NULL),
 208     relaxation_debug_check_(NULL)
 209 {
 210   // Make space for more than enough segments for a typical file.
 211   // This is just for efficiency--it's OK if we wind up needing more.
 212   this->segment_list_.reserve(12);
 213
 214   // We expect two unattached Output_data objects: the file header and
 215   // the segment headers.
 216   this->special_output_list_.reserve(2);
 217
 218   // Initialize structure needed for an incremental build.
 219   if (parameters->options().incremental())
 220     this->incremental_inputs_ = new Incremental_inputs;
 221
 222   // The section name pool is worth optimizing in all cases, because
 223   // it is small, but there are often overlaps due to .rel sections.
 224   this->namepool_.set_optimize();
 225 }
 226
 227 // Hash a key we use to look up an output section mapping.
 228
 229 size_t
 230 Layout::Hash_key::operator()(const Layout::Key& k) const
 231 {
 232  return k.first + k.second.first + k.second.second;
 233 }
 234
 235 // Returns whether the given section is in the list of
 236 // debug-sections-used-by-some-version-of-gdb.  Currently,
 237 // we've checked versions of gdb up to and including 6.7.1.
 238
 239 static const char* gdb_sections[] =
 240 { ".debug_abbrev",
 241   // ".debug_aranges",   // not used by gdb as of 6.7.1
 242   ".debug_frame",
 243   ".debug_info",
 244   ".debug_line",
 245   ".debug_loc",
 246   ".debug_macinfo",
 247   // ".debug_pubnames",  // not used by gdb as of 6.7.1
 248   ".debug_ranges",
 249   ".debug_str",
 250 };
 251
 252 static const char* lines_only_debug_sections[] =
 253 { ".debug_abbrev",
 254   // ".debug_aranges",   // not used by gdb as of 6.7.1
 255   // ".debug_frame",
 256   ".debug_info",
 257   ".debug_line",
 258   // ".debug_loc",
 259   // ".debug_macinfo",
 260   // ".debug_pubnames",  // not used by gdb as of 6.7.1
 261   // ".debug_ranges",
 262   ".debug_str",
 263 };
 264
 265 static inline bool
 266 is_gdb_debug_section(const char* str)
 267 {
 268   // We can do this faster: binary search or a hashtable.  But why bother?
 269   for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i)
 270     if (strcmp(str, gdb_sections[i]) == 0)
 271       return true;
 272   return false;
 273 }
 274
 275 static inline bool
 276 is_lines_only_debug_section(const char* str)
 277 {
 278   // We can do this faster: binary search or a hashtable.  But why bother?
 279   for (size_t i = 0;
 280        i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections);
 281        ++i)
 282     if (strcmp(str, lines_only_debug_sections[i]) == 0)
 283       return true;
 284   return false;
 285 }
 286
 287 // Whether to include this section in the link.
 288
 289 template<int size, bool big_endian>
 290 bool
 291 Layout::include_section(Sized_relobj<size, big_endian>*, const char* name,
 292                         const elfcpp::Shdr<size, big_endian>& shdr)
 293 {
 294   if (shdr.get_sh_flags() & elfcpp::SHF_EXCLUDE)
 295     return false;
 296
 297   switch (shdr.get_sh_type())
 298     {
 299     case elfcpp::SHT_NULL:
 300     case elfcpp::SHT_SYMTAB:
 301     case elfcpp::SHT_DYNSYM:
 302     case elfcpp::SHT_HASH:
 303     case elfcpp::SHT_DYNAMIC:
 304     case elfcpp::SHT_SYMTAB_SHNDX:
 305       return false;
 306
 307     case elfcpp::SHT_STRTAB:
 308       // Discard the sections which have special meanings in the ELF
 309       // ABI.  Keep others (e.g., .stabstr).  We could also do this by
 310       // checking the sh_link fields of the appropriate sections.
 311       return (strcmp(name, ".dynstr") != 0
 312               && strcmp(name, ".strtab") != 0
 313               && strcmp(name, ".shstrtab") != 0);
 314
 315     case elfcpp::SHT_RELA:
 316     case elfcpp::SHT_REL:
 317     case elfcpp::SHT_GROUP:
 318       // If we are emitting relocations these should be handled
 319       // elsewhere.
 320       gold_assert(!parameters->options().relocatable()
 321                   && !parameters->options().emit_relocs());
 322       return false;
 323
 324     case elfcpp::SHT_PROGBITS:
 325       if (parameters->options().strip_debug()
 326           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
 327         {
 328           if (is_debug_info_section(name))
 329             return false;
 330         }
 331       if (parameters->options().strip_debug_non_line()
 332           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
 333         {
 334           // Debugging sections can only be recognized by name.
 335           if (is_prefix_of(".debug", name)
 336               && !is_lines_only_debug_section(name))
 337             return false;
 338         }
 339       if (parameters->options().strip_debug_gdb()
 340           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
 341         {
 342           // Debugging sections can only be recognized by name.
 343           if (is_prefix_of(".debug", name)
 344               && !is_gdb_debug_section(name))
 345             return false;
 346         }
 347       if (parameters->options().strip_lto_sections()
 348           && !parameters->options().relocatable()
 349           && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
 350         {
 351           // Ignore LTO sections containing intermediate code.
 352           if (is_prefix_of(".gnu.lto_", name))
 353             return false;
 354         }
 355       // The GNU linker strips .gnu_debuglink sections, so we do too.
 356       // This is a feature used to keep debugging information in
 357       // separate files.
 358       if (strcmp(name, ".gnu_debuglink") == 0)
 359         return false;
 360       return true;
 361
 362     default:
 363       return true;
 364     }
 365 }
 366
 367 // Return an output section named NAME, or NULL if there is none.
 368
 369 Output_section*
 370 Layout::find_output_section(const char* name) const
 371 {
 372   for (Section_list::const_iterator p = this->section_list_.begin();
 373        p != this->section_list_.end();
 374        ++p)
 375     if (strcmp((*p)->name(), name) == 0)
 376       return *p;
 377   return NULL;
 378 }
 379
 380 // Return an output segment of type TYPE, with segment flags SET set
 381 // and segment flags CLEAR clear.  Return NULL if there is none.
 382
 383 Output_segment*
 384 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
 385                             elfcpp::Elf_Word clear) const
 386 {
 387   for (Segment_list::const_iterator p = this->segment_list_.begin();
 388        p != this->segment_list_.end();
 389        ++p)
 390     if (static_cast<elfcpp::PT>((*p)->type()) == type
 391         && ((*p)->flags() & set) == set
 392         && ((*p)->flags() & clear) == 0)
 393       return *p;
 394   return NULL;
 395 }
 396
 397 // Return the output section to use for section NAME with type TYPE
 398 // and section flags FLAGS.  NAME must be canonicalized in the string
 399 // pool, and NAME_KEY is the key.  IS_INTERP is true if this is the
 400 // .interp section.  IS_DYNAMIC_LINKER_SECTION is true if this section
 401 // is used by the dynamic linker.  IS_RELRO is true for a relro
 402 // section.  IS_LAST_RELRO is true for the last relro section.
 403 // IS_FIRST_NON_RELRO is true for the first non-relro section.
 404
 405 Output_section*
 406 Layout::get_output_section(const char* name, Stringpool::Key name_key,
 407                            elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
 408                            bool is_interp, bool is_dynamic_linker_section,
 409                            bool is_relro, bool is_last_relro,
 410                            bool is_first_non_relro)
 411 {
 412   elfcpp::Elf_Xword lookup_flags = flags;
 413
 414   // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
 415   // read-write with read-only sections.  Some other ELF linkers do
 416   // not do this.  FIXME: Perhaps there should be an option
 417   // controlling this.
 418   lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
 419
 420   const Key key(name_key, std::make_pair(type, lookup_flags));
 421   const std::pair<Key, Output_section*> v(key, NULL);
 422   std::pair<Section_name_map::iterator, bool> ins(
 423     this->section_name_map_.insert(v));
 424
 425   if (!ins.second)
 426     return ins.first->second;
 427   else
 428     {
 429       // This is the first time we've seen this name/type/flags
 430       // combination.  For compatibility with the GNU linker, we
 431       // combine sections with contents and zero flags with sections
 432       // with non-zero flags.  This is a workaround for cases where
 433       // assembler code forgets to set section flags.  FIXME: Perhaps
 434       // there should be an option to control this.
 435       Output_section* os = NULL;
 436
 437       if (type == elfcpp::SHT_PROGBITS)
 438         {
 439           if (flags == 0)
 440             {
 441               Output_section* same_name = this->find_output_section(name);
 442               if (same_name != NULL
 443                   && same_name->type() == elfcpp::SHT_PROGBITS
 444                   && (same_name->flags() & elfcpp::SHF_TLS) == 0)
 445                 os = same_name;
 446             }
 447           else if ((flags & elfcpp::SHF_TLS) == 0)
 448             {
 449               elfcpp::Elf_Xword zero_flags = 0;
 450               const Key zero_key(name_key, std::make_pair(type, zero_flags));
 451               Section_name_map::iterator p =
 452                   this->section_name_map_.find(zero_key);
 453               if (p != this->section_name_map_.end())
 454                 os = p->second;
 455             }
 456         }
 457
 458       if (os == NULL)
 459         os = this->make_output_section(name, type, flags, is_interp,
 460                                        is_dynamic_linker_section, is_relro,
 461                                        is_last_relro, is_first_non_relro);
 462       ins.first->second = os;
 463       return os;
 464     }
 465 }
 466
 467 // Pick the output section to use for section NAME, in input file
 468 // RELOBJ, with type TYPE and flags FLAGS.  RELOBJ may be NULL for a
 469 // linker created section.  IS_INPUT_SECTION is true if we are
 470 // choosing an output section for an input section found in a input
 471 // file.  IS_INTERP is true if this is the .interp section.
 472 // IS_DYNAMIC_LINKER_SECTION is true if this section is used by the
 473 // dynamic linker.  IS_RELRO is true for a relro section.
 474 // IS_LAST_RELRO is true for the last relro section.
 475 // IS_FIRST_NON_RELRO is true for the first non-relro section.  This
 476 // will return NULL if the input section should be discarded.
 477
 478 Output_section*
 479 Layout::choose_output_section(const Relobj* relobj, const char* name,
 480                               elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
 481                               bool is_input_section, bool is_interp,
 482                               bool is_dynamic_linker_section, bool is_relro,
 483                               bool is_last_relro, bool is_first_non_relro)
 484 {
 485   // We should not see any input sections after we have attached
 486   // sections to segments.
 487   gold_assert(!is_input_section || !this->sections_are_attached_);
 488
 489   // Some flags in the input section should not be automatically
 490   // copied to the output section.
 491   flags &= ~ (elfcpp::SHF_INFO_LINK
 492               | elfcpp::SHF_LINK_ORDER
 493               | elfcpp::SHF_GROUP
 494               | elfcpp::SHF_MERGE
 495               | elfcpp::SHF_STRINGS);
 496
 497   if (this->script_options_->saw_sections_clause())
 498     {
 499       // We are using a SECTIONS clause, so the output section is
 500       // chosen based only on the name.
 501
 502       Script_sections* ss = this->script_options_->script_sections();
 503       const char* file_name = relobj == NULL ? NULL : relobj->name().c_str();
 504       Output_section** output_section_slot;
 505       name = ss->output_section_name(file_name, name, &output_section_slot);
 506       if (name == NULL)
 507         {
 508           // The SECTIONS clause says to discard this input section.
 509           return NULL;
 510         }
 511
 512       // If this is an orphan section--one not mentioned in the linker
 513       // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the
 514       // default processing below.
 515
 516       if (output_section_slot != NULL)
 517         {
 518           if (*output_section_slot != NULL)
 519             {
 520               (*output_section_slot)->update_flags_for_input_section(flags);
 521               return *output_section_slot;
 522             }
 523
 524           // We don't put sections found in the linker script into
 525           // SECTION_NAME_MAP_.  That keeps us from getting confused
 526           // if an orphan section is mapped to a section with the same
 527           // name as one in the linker script.
 528
 529           name = this->namepool_.add(name, false, NULL);
 530
 531           Output_section* os =
 532             this->make_output_section(name, type, flags, is_interp,
 533                                       is_dynamic_linker_section, is_relro,
 534                                       is_last_relro, is_first_non_relro);
 535           os->set_found_in_sections_clause();
 536           *output_section_slot = os;
 537           return os;
 538         }
 539     }
 540
 541   // FIXME: Handle SHF_OS_NONCONFORMING somewhere.
 542
 543   // Turn NAME from the name of the input section into the name of the
 544   // output section.
 545
 546   size_t len = strlen(name);
 547   if (is_input_section
 548       && !this->script_options_->saw_sections_clause()
 549       && !parameters->options().relocatable())
 550     name = Layout::output_section_name(name, &len);
 551
 552   Stringpool::Key name_key;
 553   name = this->namepool_.add_with_length(name, len, true, &name_key);
 554
 555   // Find or make the output section.  The output section is selected
 556   // based on the section name, type, and flags.
 557   return this->get_output_section(name, name_key, type, flags, is_interp,
 558                                   is_dynamic_linker_section, is_relro,
 559                                   is_last_relro, is_first_non_relro);
 560 }
 561
 562 // Return the output section to use for input section SHNDX, with name
 563 // NAME, with header HEADER, from object OBJECT.  RELOC_SHNDX is the
 564 // index of a relocation section which applies to this section, or 0
 565 // if none, or -1U if more than one.  RELOC_TYPE is the type of the
 566 // relocation section if there is one.  Set *OFF to the offset of this
 567 // input section without the output section.  Return NULL if the
 568 // section should be discarded.  Set *OFF to -1 if the section
 569 // contents should not be written directly to the output file, but
 570 // will instead receive special handling.
 571
 572 template<int size, bool big_endian>
 573 Output_section*
 574 Layout::layout(Sized_relobj<size, big_endian>* object, unsigned int shndx,
 575                const char* name, const elfcpp::Shdr<size, big_endian>& shdr,
 576                unsigned int reloc_shndx, unsigned int, off_t* off)
 577 {
 578   *off = 0;
 579
 580   if (!this->include_section(object, name, shdr))
 581     return NULL;
 582
 583   Output_section* os;
 584
 585   // Sometimes .init_array*, .preinit_array* and .fini_array* do not have
 586   // correct section types.  Force them here.
 587   elfcpp::Elf_Word sh_type = shdr.get_sh_type();
 588   if (sh_type == elfcpp::SHT_PROGBITS)
 589     {
 590       static const char init_array_prefix[] = ".init_array";
 591       static const char preinit_array_prefix[] = ".preinit_array";
 592       static const char fini_array_prefix[] = ".fini_array";
 593       static size_t init_array_prefix_size = sizeof(init_array_prefix) - 1;
 594       static size_t preinit_array_prefix_size =
 595         sizeof(preinit_array_prefix) - 1;
 596       static size_t fini_array_prefix_size = sizeof(fini_array_prefix) - 1;
 597
 598       if (strncmp(name, init_array_prefix, init_array_prefix_size) == 0)
 599         sh_type = elfcpp::SHT_INIT_ARRAY;
 600       else if (strncmp(name, preinit_array_prefix, preinit_array_prefix_size)
 601                == 0)
 602         sh_type = elfcpp::SHT_PREINIT_ARRAY;
 603       else if (strncmp(name, fini_array_prefix, fini_array_prefix_size) == 0)
 604         sh_type = elfcpp::SHT_FINI_ARRAY;
 605     }
 606
 607   // In a relocatable link a grouped section must not be combined with
 608   // any other sections.
 609   if (parameters->options().relocatable()
 610       && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0)
 611     {
 612       name = this->namepool_.add(name, true, NULL);
 613       os = this->make_output_section(name, sh_type, shdr.get_sh_flags(), false,
 614                                      false, false, false, false);
 615     }
 616   else
 617     {
 618       os = this->choose_output_section(object, name, sh_type,
 619                                        shdr.get_sh_flags(), true, false,
 620                                        false, false, false, false);
 621       if (os == NULL)
 622         return NULL;
 623     }
 624
 625   // By default the GNU linker sorts input sections whose names match
 626   // .ctor.*, .dtor.*, .init_array.*, or .fini_array.*.  The sections
 627   // are sorted by name.  This is used to implement constructor
 628   // priority ordering.  We are compatible.
 629   if (!this->script_options_->saw_sections_clause()
 630       && (is_prefix_of(".ctors.", name)
 631           || is_prefix_of(".dtors.", name)
 632           || is_prefix_of(".init_array.", name)
 633           || is_prefix_of(".fini_array.", name)))
 634     os->set_must_sort_attached_input_sections();
 635
 636   // FIXME: Handle SHF_LINK_ORDER somewhere.
 637
 638   *off = os->add_input_section(object, shndx, name, shdr, reloc_shndx,
 639                                this->script_options_->saw_sections_clause());
 640   this->have_added_input_section_ = true;
 641
 642   return os;
 643 }
 644
 645 // Handle a relocation section when doing a relocatable link.
 646
 647 template<int size, bool big_endian>
 648 Output_section*
 649 Layout::layout_reloc(Sized_relobj<size, big_endian>* object,
 650                      unsigned int,
 651                      const elfcpp::Shdr<size, big_endian>& shdr,
 652                      Output_section* data_section,
 653                      Relocatable_relocs* rr)
 654 {
 655   gold_assert(parameters->options().relocatable()
 656               || parameters->options().emit_relocs());
 657
 658   int sh_type = shdr.get_sh_type();
 659
 660   std::string name;
 661   if (sh_type == elfcpp::SHT_REL)
 662     name = ".rel";
 663   else if (sh_type == elfcpp::SHT_RELA)
 664     name = ".rela";
 665   else
 666     gold_unreachable();
 667   name += data_section->name();
 668
 669   Output_section* os = this->choose_output_section(object, name.c_str(),
 670                                                    sh_type,
 671                                                    shdr.get_sh_flags(),
 672                                                    false, false, false,
 673                                                    false, false, false);
 674
 675   os->set_should_link_to_symtab();
 676   os->set_info_section(data_section);
 677
 678   Output_section_data* posd;
 679   if (sh_type == elfcpp::SHT_REL)
 680     {
 681       os->set_entsize(elfcpp::Elf_sizes<size>::rel_size);
 682       posd = new Output_relocatable_relocs<elfcpp::SHT_REL,
 683                                            size,
 684                                            big_endian>(rr);
 685     }
 686   else if (sh_type == elfcpp::SHT_RELA)
 687     {
 688       os->set_entsize(elfcpp::Elf_sizes<size>::rela_size);
 689       posd = new Output_relocatable_relocs<elfcpp::SHT_RELA,
 690                                            size,
 691                                            big_endian>(rr);
 692     }
 693   else
 694     gold_unreachable();
 695
 696   os->add_output_section_data(posd);
 697   rr->set_output_data(posd);
 698
 699   return os;
 700 }
 701
 702 // Handle a group section when doing a relocatable link.
 703
 704 template<int size, bool big_endian>
 705 void
 706 Layout::layout_group(Symbol_table* symtab,
 707                      Sized_relobj<size, big_endian>* object,
 708                      unsigned int,
 709                      const char* group_section_name,
 710                      const char* signature,
 711                      const elfcpp::Shdr<size, big_endian>& shdr,
 712                      elfcpp::Elf_Word flags,
 713                      std::vector<unsigned int>* shndxes)
 714 {
 715   gold_assert(parameters->options().relocatable());
 716   gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP);
 717   group_section_name = this->namepool_.add(group_section_name, true, NULL);
 718   Output_section* os = this->make_output_section(group_section_name,
 719                                                  elfcpp::SHT_GROUP,
 720                                                  shdr.get_sh_flags(),
 721                                                  false, false, false,
 722                                                  false, false);
 723
 724   // We need to find a symbol with the signature in the symbol table.
 725   // If we don't find one now, we need to look again later.
 726   Symbol* sym = symtab->lookup(signature, NULL);
 727   if (sym != NULL)
 728     os->set_info_symndx(sym);
 729   else
 730     {
 731       // Reserve some space to minimize reallocations.
 732       if (this->group_signatures_.empty())
 733         this->group_signatures_.reserve(this->number_of_input_files_ * 16);
 734
 735       // We will wind up using a symbol whose name is the signature.
 736       // So just put the signature in the symbol name pool to save it.
 737       signature = symtab->canonicalize_name(signature);
 738       this->group_signatures_.push_back(Group_signature(os, signature));
 739     }
 740
 741   os->set_should_link_to_symtab();
 742   os->set_entsize(4);
 743
 744   section_size_type entry_count =
 745     convert_to_section_size_type(shdr.get_sh_size() / 4);
 746   Output_section_data* posd =
 747     new Output_data_group<size, big_endian>(object, entry_count, flags,
 748                                             shndxes);
 749   os->add_output_section_data(posd);
 750 }
 751
 752 // Special GNU handling of sections name .eh_frame.  They will
 753 // normally hold exception frame data as defined by the C++ ABI
 754 // (http://codesourcery.com/cxx-abi/).
 755
 756 template<int size, bool big_endian>
 757 Output_section*
 758 Layout::layout_eh_frame(Sized_relobj<size, big_endian>* object,
 759                         const unsigned char* symbols,
 760                         off_t symbols_size,
 761                         const unsigned char* symbol_names,
 762                         off_t symbol_names_size,
 763                         unsigned int shndx,
 764                         const elfcpp::Shdr<size, big_endian>& shdr,
 765                         unsigned int reloc_shndx, unsigned int reloc_type,
 766                         off_t* off)
 767 {
 768   gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS);
 769   gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
 770
 771   const char* const name = ".eh_frame";
 772   Output_section* os = this->choose_output_section(object,
 773                                                    name,
 774                                                    elfcpp::SHT_PROGBITS,
 775                                                    elfcpp::SHF_ALLOC,
 776                                                    false, false, false,
 777                                                    false, false, false);
 778   if (os == NULL)
 779     return NULL;
 780
 781   if (this->eh_frame_section_ == NULL)
 782     {
 783       this->eh_frame_section_ = os;
 784       this->eh_frame_data_ = new Eh_frame();
 785
 786       if (parameters->options().eh_frame_hdr())
 787         {
 788           Output_section* hdr_os =
 789             this->choose_output_section(NULL,
 790                                         ".eh_frame_hdr",
 791                                         elfcpp::SHT_PROGBITS,
 792                                         elfcpp::SHF_ALLOC,
 793                                         false, false, false,
 794                                         false, false, false);
 795
 796           if (hdr_os != NULL)
 797             {
 798               Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os,
 799                                                         this->eh_frame_data_);
 800               hdr_os->add_output_section_data(hdr_posd);
 801
 802               hdr_os->set_after_input_sections();
 803
 804               if (!this->script_options_->saw_phdrs_clause())
 805                 {
 806                   Output_segment* hdr_oseg;
 807                   hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME,
 808                                                        elfcpp::PF_R);
 809                   hdr_oseg->add_output_section(hdr_os, elfcpp::PF_R, false);
 810                 }
 811
 812               this->eh_frame_data_->set_eh_frame_hdr(hdr_posd);
 813             }
 814         }
 815     }
 816
 817   gold_assert(this->eh_frame_section_ == os);
 818
 819   if (this->eh_frame_data_->add_ehframe_input_section(object,
 820                                                       symbols,
 821                                                       symbols_size,
 822                                                       symbol_names,
 823                                                       symbol_names_size,
 824                                                       shndx,
 825                                                       reloc_shndx,
 826                                                       reloc_type))
 827     {
 828       os->update_flags_for_input_section(shdr.get_sh_flags());
 829
 830       // We found a .eh_frame section we are going to optimize, so now
 831       // we can add the set of optimized sections to the output
 832       // section.  We need to postpone adding this until we've found a
 833       // section we can optimize so that the .eh_frame section in
 834       // crtbegin.o winds up at the start of the output section.
 835       if (!this->added_eh_frame_data_)
 836         {
 837           os->add_output_section_data(this->eh_frame_data_);
 838           this->added_eh_frame_data_ = true;
 839         }
 840       *off = -1;
 841     }
 842   else
 843     {
 844       // We couldn't handle this .eh_frame section for some reason.
 845       // Add it as a normal section.
 846       bool saw_sections_clause = this->script_options_->saw_sections_clause();
 847       *off = os->add_input_section(object, shndx, name, shdr, reloc_shndx,
 848                                    saw_sections_clause);
 849       this->have_added_input_section_ = true;
 850     }
 851
 852   return os;
 853 }
 854
 855 // Add POSD to an output section using NAME, TYPE, and FLAGS.  Return
 856 // the output section.
 857
 858 Output_section*
 859 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
 860                                 elfcpp::Elf_Xword flags,
 861                                 Output_section_data* posd,
 862                                 bool is_dynamic_linker_section,
 863                                 bool is_relro, bool is_last_relro,
 864                                 bool is_first_non_relro)
 865 {
 866   Output_section* os = this->choose_output_section(NULL, name, type, flags,
 867                                                    false, false,
 868                                                    is_dynamic_linker_section,
 869                                                    is_relro, is_last_relro,
 870                                                    is_first_non_relro);
 871   if (os != NULL)
 872     os->add_output_section_data(posd);
 873   return os;
 874 }
 875
 876 // Map section flags to segment flags.
 877
 878 elfcpp::Elf_Word
 879 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
 880 {
 881   elfcpp::Elf_Word ret = elfcpp::PF_R;
 882   if ((flags & elfcpp::SHF_WRITE) != 0)
 883     ret |= elfcpp::PF_W;
 884   if ((flags & elfcpp::SHF_EXECINSTR) != 0)
 885     ret |= elfcpp::PF_X;
 886   return ret;
 887 }
 888
 889 // Sometimes we compress sections.  This is typically done for
 890 // sections that are not part of normal program execution (such as
 891 // .debug_* sections), and where the readers of these sections know
 892 // how to deal with compressed sections.  This routine doesn't say for
 893 // certain whether we'll compress -- it depends on commandline options
 894 // as well -- just whether this section is a candidate for compression.
 895 // (The Output_compressed_section class decides whether to compress
 896 // a given section, and picks the name of the compressed section.)
 897
 898 static bool
 899 is_compressible_debug_section(const char* secname)
 900 {
 901   return (strncmp(secname, ".debug", sizeof(".debug") - 1) == 0);
 902 }
 903
 904 // Make a new Output_section, and attach it to segments as
 905 // appropriate.  IS_INTERP is true if this is the .interp section.
 906 // IS_DYNAMIC_LINKER_SECTION is true if this section is used by the
 907 // dynamic linker.  IS_RELRO is true if this is a relro section.
 908 // IS_LAST_RELRO is true if this is the last relro section.
 909 // IS_FIRST_NON_RELRO is true if this is the first non relro section.
 910
 911 Output_section*
 912 Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
 913                             elfcpp::Elf_Xword flags, bool is_interp,
 914                             bool is_dynamic_linker_section, bool is_relro,
 915                             bool is_last_relro, bool is_first_non_relro)
 916 {
 917   Output_section* os;
 918   if ((flags & elfcpp::SHF_ALLOC) == 0
 919       && strcmp(parameters->options().compress_debug_sections(), "none") != 0
 920       && is_compressible_debug_section(name))
 921     os = new Output_compressed_section(&parameters->options(), name, type,
 922                                        flags);
 923   else if ((flags & elfcpp::SHF_ALLOC) == 0
 924            && parameters->options().strip_debug_non_line()
 925            && strcmp(".debug_abbrev", name) == 0)
 926     {
 927       os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section(
 928           name, type, flags);
 929       if (this->debug_info_)
 930         this->debug_info_->set_abbreviations(this->debug_abbrev_);
 931     }
 932   else if ((flags & elfcpp::SHF_ALLOC) == 0
 933            && parameters->options().strip_debug_non_line()
 934            && strcmp(".debug_info", name) == 0)
 935     {
 936       os = this->debug_info_ = new Output_reduced_debug_info_section(
 937           name, type, flags);
 938       if (this->debug_abbrev_)
 939         this->debug_info_->set_abbreviations(this->debug_abbrev_);
 940     }
 941  else
 942     {
 943       // FIXME: const_cast is ugly.
 944       Target* target = const_cast<Target*>(&parameters->target());
 945       os = target->make_output_section(name, type, flags);
 946     }
 947
 948   if (is_interp)
 949     os->set_is_interp();
 950   if (is_dynamic_linker_section)
 951     os->set_is_dynamic_linker_section();
 952   if (is_relro)
 953     os->set_is_relro();
 954   if (is_last_relro)
 955     os->set_is_last_relro();
 956   if (is_first_non_relro)
 957     os->set_is_first_non_relro();
 958
 959   parameters->target().new_output_section(os);
 960
 961   this->section_list_.push_back(os);
 962
 963   // The GNU linker by default sorts some sections by priority, so we
 964   // do the same.  We need to know that this might happen before we
 965   // attach any input sections.
 966   if (!this->script_options_->saw_sections_clause()
 967       && (strcmp(name, ".ctors") == 0
 968           || strcmp(name, ".dtors") == 0
 969           || strcmp(name, ".init_array") == 0
 970           || strcmp(name, ".fini_array") == 0))
 971     os->set_may_sort_attached_input_sections();
 972
 973   // With -z relro, we have to recognize the special sections by name.
 974   // There is no other way.
 975   if (!this->script_options_->saw_sections_clause()
 976       && parameters->options().relro()
 977       && type == elfcpp::SHT_PROGBITS
 978       && (flags & elfcpp::SHF_ALLOC) != 0
 979       && (flags & elfcpp::SHF_WRITE) != 0)
 980     {
 981       if (strcmp(name, ".data.rel.ro") == 0)
 982         os->set_is_relro();
 983       else if (strcmp(name, ".data.rel.ro.local") == 0)
 984         {
 985           os->set_is_relro();
 986           os->set_is_relro_local();
 987         }
 988     }
 989
 990   // Check for .stab*str sections, as .stab* sections need to link to
 991   // them.
 992   if (type == elfcpp::SHT_STRTAB
 993       && !this->have_stabstr_section_
 994       && strncmp(name, ".stab", 5) == 0
 995       && strcmp(name + strlen(name) - 3, "str") == 0)
 996     this->have_stabstr_section_ = true;
 997
 998   // If we have already attached the sections to segments, then we
 999   // need to attach this one now.  This happens for sections created
1000   // directly by the linker.
1001   if (this->sections_are_attached_)
1002     this->attach_section_to_segment(os);
1003
1004   return os;
1005 }
1006
1007 // Attach output sections to segments.  This is called after we have
1008 // seen all the input sections.
1009
1010 void
1011 Layout::attach_sections_to_segments()
1012 {
1013   for (Section_list::iterator p = this->section_list_.begin();
1014        p != this->section_list_.end();
1015        ++p)
1016     this->attach_section_to_segment(*p);
1017
1018   this->sections_are_attached_ = true;
1019 }
1020
1021 // Attach an output section to a segment.
1022
1023 void
1024 Layout::attach_section_to_segment(Output_section* os)
1025 {
1026   if ((os->flags() & elfcpp::SHF_ALLOC) == 0)
1027     this->unattached_section_list_.push_back(os);
1028   else
1029     this->attach_allocated_section_to_segment(os);
1030 }
1031
1032 // Attach an allocated output section to a segment.
1033
1034 void
1035 Layout::attach_allocated_section_to_segment(Output_section* os)
1036 {
1037   elfcpp::Elf_Xword flags = os->flags();
1038   gold_assert((flags & elfcpp::SHF_ALLOC) != 0);
1039
1040   if (parameters->options().relocatable())
1041     return;
1042
1043   // If we have a SECTIONS clause, we can't handle the attachment to
1044   // segments until after we've seen all the sections.
1045   if (this->script_options_->saw_sections_clause())
1046     return;
1047
1048   gold_assert(!this->script_options_->saw_phdrs_clause());
1049
1050   // This output section goes into a PT_LOAD segment.
1051
1052   elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
1053
1054   // Check for --section-start.
1055   uint64_t addr;
1056   bool is_address_set = parameters->options().section_start(os->name(), &addr);
1057
1058   // In general the only thing we really care about for PT_LOAD
1059   // segments is whether or not they are writable, so that is how we
1060   // search for them.  Large data sections also go into their own
1061   // PT_LOAD segment.  People who need segments sorted on some other
1062   // basis will have to use a linker script.
1063
1064   Segment_list::const_iterator p;
1065   for (p = this->segment_list_.begin();
1066        p != this->segment_list_.end();
1067        ++p)
1068     {
1069       if ((*p)->type() != elfcpp::PT_LOAD)
1070         continue;
1071       if (!parameters->options().omagic()
1072           && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
1073         continue;
1074       // If -Tbss was specified, we need to separate the data and BSS
1075       // segments.
1076       if (parameters->options().user_set_Tbss())
1077         {
1078           if ((os->type() == elfcpp::SHT_NOBITS)
1079               == (*p)->has_any_data_sections())
1080             continue;
1081         }
1082       if (os->is_large_data_section() && !(*p)->is_large_data_segment())
1083         continue;
1084
1085       if (is_address_set)
1086         {
1087           if ((*p)->are_addresses_set())
1088             continue;
1089
1090           (*p)->add_initial_output_data(os);
1091           (*p)->update_flags_for_output_section(seg_flags);
1092           (*p)->set_addresses(addr, addr);
1093           break;
1094         }
1095
1096       (*p)->add_output_section(os, seg_flags, true);
1097       break;
1098     }
1099
1100   if (p == this->segment_list_.end())
1101     {
1102       Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
1103                                                        seg_flags);
1104       if (os->is_large_data_section())
1105         oseg->set_is_large_data_segment();
1106       oseg->add_output_section(os, seg_flags, true);
1107       if (is_address_set)
1108         oseg->set_addresses(addr, addr);
1109     }
1110
1111   // If we see a loadable SHT_NOTE section, we create a PT_NOTE
1112   // segment.
1113   if (os->type() == elfcpp::SHT_NOTE)
1114     {
1115       // See if we already have an equivalent PT_NOTE segment.
1116       for (p = this->segment_list_.begin();
1117            p != segment_list_.end();
1118            ++p)
1119         {
1120           if ((*p)->type() == elfcpp::PT_NOTE
1121               && (((*p)->flags() & elfcpp::PF_W)
1122                   == (seg_flags & elfcpp::PF_W)))
1123             {
1124               (*p)->add_output_section(os, seg_flags, false);
1125               break;
1126             }
1127         }
1128
1129       if (p == this->segment_list_.end())
1130         {
1131           Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
1132                                                            seg_flags);
1133           oseg->add_output_section(os, seg_flags, false);
1134         }
1135     }
1136
1137   // If we see a loadable SHF_TLS section, we create a PT_TLS
1138   // segment.  There can only be one such segment.
1139   if ((flags & elfcpp::SHF_TLS) != 0)
1140     {
1141       if (this->tls_segment_ == NULL)
1142         this->make_output_segment(elfcpp::PT_TLS, seg_flags);
1143       this->tls_segment_->add_output_section(os, seg_flags, false);
1144     }
1145
1146   // If -z relro is in effect, and we see a relro section, we create a
1147   // PT_GNU_RELRO segment.  There can only be one such segment.
1148   if (os->is_relro() && parameters->options().relro())
1149     {
1150       gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W));
1151       if (this->relro_segment_ == NULL)
1152         this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags);
1153       this->relro_segment_->add_output_section(os, seg_flags, false);
1154     }
1155 }
1156
1157 // Make an output section for a script.
1158
1159 Output_section*
1160 Layout::make_output_section_for_script(const char* name)
1161 {
1162   name = this->namepool_.add(name, false, NULL);
1163   Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS,
1164                                                  elfcpp::SHF_ALLOC, false,
1165                                                  false, false, false, false);
1166   os->set_found_in_sections_clause();
1167   return os;
1168 }
1169
1170 // Return the number of segments we expect to see.
1171
1172 size_t
1173 Layout::expected_segment_count() const
1174 {
1175   size_t ret = this->segment_list_.size();
1176
1177   // If we didn't see a SECTIONS clause in a linker script, we should
1178   // already have the complete list of segments.  Otherwise we ask the
1179   // SECTIONS clause how many segments it expects, and add in the ones
1180   // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.)
1181
1182   if (!this->script_options_->saw_sections_clause())
1183     return ret;
1184   else
1185     {
1186       const Script_sections* ss = this->script_options_->script_sections();
1187       return ret + ss->expected_segment_count(this);
1188     }
1189 }
1190
1191 // Handle the .note.GNU-stack section at layout time.  SEEN_GNU_STACK
1192 // is whether we saw a .note.GNU-stack section in the object file.
1193 // GNU_STACK_FLAGS is the section flags.  The flags give the
1194 // protection required for stack memory.  We record this in an
1195 // executable as a PT_GNU_STACK segment.  If an object file does not
1196 // have a .note.GNU-stack segment, we must assume that it is an old
1197 // object.  On some targets that will force an executable stack.
1198
1199 void
1200 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags)
1201 {
1202   if (!seen_gnu_stack)
1203     this->input_without_gnu_stack_note_ = true;
1204   else
1205     {
1206       this->input_with_gnu_stack_note_ = true;
1207       if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0)
1208         this->input_requires_executable_stack_ = true;
1209     }
1210 }
1211
1212 // Create automatic note sections.
1213
1214 void
1215 Layout::create_notes()
1216 {
1217   this->create_gold_note();
1218   this->create_executable_stack_info();
1219   this->create_build_id();
1220 }
1221
1222 // Create the dynamic sections which are needed before we read the
1223 // relocs.
1224
1225 void
1226 Layout::create_initial_dynamic_sections(Symbol_table* symtab)
1227 {
1228   if (parameters->doing_static_link())
1229     return;
1230
1231   this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic",
1232                                                        elfcpp::SHT_DYNAMIC,
1233                                                        (elfcpp::SHF_ALLOC
1234                                                         | elfcpp::SHF_WRITE),
1235                                                        false, false, true,
1236                                                        true, false, false);
1237
1238   this->dynamic_symbol_ =
1239     symtab->define_in_output_data("_DYNAMIC", NULL, Symbol_table::PREDEFINED,
1240                                   this->dynamic_section_, 0, 0,
1241                                   elfcpp::STT_OBJECT, elfcpp::STB_LOCAL,
1242                                   elfcpp::STV_HIDDEN, 0, false, false);
1243
1244   this->dynamic_data_ =  new Output_data_dynamic(&this->dynpool_);
1245
1246   this->dynamic_section_->add_output_section_data(this->dynamic_data_);
1247 }
1248
1249 // For each output section whose name can be represented as C symbol,
1250 // define __start and __stop symbols for the section.  This is a GNU
1251 // extension.
1252
1253 void
1254 Layout::define_section_symbols(Symbol_table* symtab)
1255 {
1256   for (Section_list::const_iterator p = this->section_list_.begin();
1257        p != this->section_list_.end();
1258        ++p)
1259     {
1260       const char* const name = (*p)->name();
1261       if (is_cident(name))
1262         {
1263           const std::string name_string(name);
1264           const std::string start_name(cident_section_start_prefix
1265                                        + name_string);
1266           const std::string stop_name(cident_section_stop_prefix
1267                                       + name_string);
1268
1269           symtab->define_in_output_data(start_name.c_str(),
1270                                         NULL, // version
1271                                         Symbol_table::PREDEFINED,
1272                                         *p,
1273                                         0, // value
1274                                         0, // symsize
1275                                         elfcpp::STT_NOTYPE,
1276                                         elfcpp::STB_GLOBAL,
1277                                         elfcpp::STV_DEFAULT,
1278                                         0, // nonvis
1279                                         false, // offset_is_from_end
1280                                         true); // only_if_ref
1281
1282           symtab->define_in_output_data(stop_name.c_str(),
1283                                         NULL, // version
1284                                         Symbol_table::PREDEFINED,
1285                                         *p,
1286                                         0, // value
1287                                         0, // symsize
1288                                         elfcpp::STT_NOTYPE,
1289                                         elfcpp::STB_GLOBAL,
1290                                         elfcpp::STV_DEFAULT,
1291                                         0, // nonvis
1292                                         true, // offset_is_from_end
1293                                         true); // only_if_ref
1294         }
1295     }
1296 }
1297
1298 // Define symbols for group signatures.
1299
1300 void
1301 Layout::define_group_signatures(Symbol_table* symtab)
1302 {
1303   for (Group_signatures::iterator p = this->group_signatures_.begin();
1304        p != this->group_signatures_.end();
1305        ++p)
1306     {
1307       Symbol* sym = symtab->lookup(p->signature, NULL);
1308       if (sym != NULL)
1309         p->section->set_info_symndx(sym);
1310       else
1311         {
1312           // Force the name of the group section to the group
1313           // signature, and use the group's section symbol as the
1314           // signature symbol.
1315           if (strcmp(p->section->name(), p->signature) != 0)
1316             {
1317               const char* name = this->namepool_.add(p->signature,
1318                                                      true, NULL);
1319               p->section->set_name(name);
1320             }
1321           p->section->set_needs_symtab_index();
1322           p->section->set_info_section_symndx(p->section);
1323         }
1324     }
1325
1326   this->group_signatures_.clear();
1327 }
1328
1329 // Find the first read-only PT_LOAD segment, creating one if
1330 // necessary.
1331
1332 Output_segment*
1333 Layout::find_first_load_seg()
1334 {
1335   for (Segment_list::const_iterator p = this->segment_list_.begin();
1336        p != this->segment_list_.end();
1337        ++p)
1338     {
1339       if ((*p)->type() == elfcpp::PT_LOAD
1340           && ((*p)->flags() & elfcpp::PF_R) != 0
1341           && (parameters->options().omagic()
1342               || ((*p)->flags() & elfcpp::PF_W) == 0))
1343         return *p;
1344     }
1345
1346   gold_assert(!this->script_options_->saw_phdrs_clause());
1347
1348   Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD,
1349                                                        elfcpp::PF_R);
1350   return load_seg;
1351 }
1352
1353 // Save states of all current output segments.  Store saved states
1354 // in SEGMENT_STATES.
1355
1356 void
1357 Layout::save_segments(Segment_states* segment_states)
1358 {
1359   for (Segment_list::const_iterator p = this->segment_list_.begin();
1360        p != this->segment_list_.end();
1361        ++p)
1362     {
1363       Output_segment* segment = *p;
1364       // Shallow copy.
1365       Output_segment* copy = new Output_segment(*segment);
1366       (*segment_states)[segment] = copy;
1367     }
1368 }
1369
1370 // Restore states of output segments and delete any segment not found in
1371 // SEGMENT_STATES.
1372
1373 void
1374 Layout::restore_segments(const Segment_states* segment_states)
1375 {
1376   // Go through the segment list and remove any segment added in the
1377   // relaxation loop.
1378   this->tls_segment_ = NULL;
1379   this->relro_segment_ = NULL;
1380   Segment_list::iterator list_iter = this->segment_list_.begin();
1381   while (list_iter != this->segment_list_.end())
1382     {
1383       Output_segment* segment = *list_iter;
1384       Segment_states::const_iterator states_iter =
1385           segment_states->find(segment);
1386       if (states_iter != segment_states->end())
1387         {
1388           const Output_segment* copy = states_iter->second;
1389           // Shallow copy to restore states.
1390           *segment = *copy;
1391
1392           // Also fix up TLS and RELRO segment pointers as appropriate.
1393           if (segment->type() == elfcpp::PT_TLS)
1394             this->tls_segment_ = segment;
1395           else if (segment->type() == elfcpp::PT_GNU_RELRO)
1396             this->relro_segment_ = segment;
1397
1398           ++list_iter;
1399         }
1400       else
1401         {
1402           list_iter = this->segment_list_.erase(list_iter);
1403           // This is a segment created during section layout.  It should be
1404           // safe to remove it since we should have removed all pointers to it.
1405           delete segment;
1406         }
1407     }
1408 }
1409
1410 // Clean up after relaxation so that sections can be laid out again.
1411
1412 void
1413 Layout::clean_up_after_relaxation()
1414 {
1415   // Restore the segments to point state just prior to the relaxation loop.
1416   Script_sections* script_section = this->script_options_->script_sections();
1417   script_section->release_segments();
1418   this->restore_segments(this->segment_states_);
1419
1420   // Reset section addresses and file offsets
1421   for (Section_list::iterator p = this->section_list_.begin();
1422        p != this->section_list_.end();
1423        ++p)
1424     {
1425       (*p)->restore_states();
1426
1427       // If an input section changes size because of relaxation,
1428       // we need to adjust the section offsets of all input sections.
1429       // after such a section.
1430       if ((*p)->section_offsets_need_adjustment())
1431         (*p)->adjust_section_offsets();
1432
1433       (*p)->reset_address_and_file_offset();
1434     }
1435
1436   // Reset special output object address and file offsets.
1437   for (Data_list::iterator p = this->special_output_list_.begin();
1438        p != this->special_output_list_.end();
1439        ++p)
1440     (*p)->reset_address_and_file_offset();
1441
1442   // A linker script may have created some output section data objects.
1443   // They are useless now.
1444   for (Output_section_data_list::const_iterator p =
1445          this->script_output_section_data_list_.begin();
1446        p != this->script_output_section_data_list_.end();
1447        ++p)
1448     delete *p;
1449   this->script_output_section_data_list_.clear();
1450 }
1451
1452 // Prepare for relaxation.
1453
1454 void
1455 Layout::prepare_for_relaxation()
1456 {
1457   // Create an relaxation debug check if in debugging mode.
1458   if (is_debugging_enabled(DEBUG_RELAXATION))
1459     this->relaxation_debug_check_ = new Relaxation_debug_check();
1460
1461   // Save segment states.
1462   this->segment_states_ = new Segment_states();
1463   this->save_segments(this->segment_states_);
1464
1465   for(Section_list::const_iterator p = this->section_list_.begin();
1466       p != this->section_list_.end();
1467       ++p)
1468     (*p)->save_states();
1469
1470   if (is_debugging_enabled(DEBUG_RELAXATION))
1471     this->relaxation_debug_check_->check_output_data_for_reset_values(
1472         this->section_list_, this->special_output_list_);
1473
1474   // Also enable recording of output section data from scripts.
1475   this->record_output_section_data_from_script_ = true;
1476 }
1477
1478 // Relaxation loop body:  If target has no relaxation, this runs only once
1479 // Otherwise, the target relaxation hook is called at the end of
1480 // each iteration.  If the hook returns true, it means re-layout of
1481 // section is required.
1482 //
1483 // The number of segments created by a linking script without a PHDRS
1484 // clause may be affected by section sizes and alignments.  There is
1485 // a remote chance that relaxation causes different number of PT_LOAD
1486 // segments are created and sections are attached to different segments.
1487 // Therefore, we always throw away all segments created during section
1488 // layout.  In order to be able to restart the section layout, we keep
1489 // a copy of the segment list right before the relaxation loop and use
1490 // that to restore the segments.
1491 //
1492 // PASS is the current relaxation pass number.
1493 // SYMTAB is a symbol table.
1494 // PLOAD_SEG is the address of a pointer for the load segment.
1495 // PHDR_SEG is a pointer to the PHDR segment.
1496 // SEGMENT_HEADERS points to the output segment header.
1497 // FILE_HEADER points to the output file header.
1498 // PSHNDX is the address to store the output section index.
1499
1500 off_t inline
1501 Layout::relaxation_loop_body(
1502     int pass,
1503     Target* target,
1504     Symbol_table* symtab,
1505     Output_segment** pload_seg,
1506     Output_segment* phdr_seg,
1507     Output_segment_headers* segment_headers,
1508     Output_file_header* file_header,
1509     unsigned int* pshndx)
1510 {
1511   // If this is not the first iteration, we need to clean up after
1512   // relaxation so that we can lay out the sections again.
1513   if (pass != 0)
1514     this->clean_up_after_relaxation();
1515
1516   // If there is a SECTIONS clause, put all the input sections into
1517   // the required order.
1518   Output_segment* load_seg;
1519   if (this->script_options_->saw_sections_clause())
1520     load_seg = this->set_section_addresses_from_script(symtab);
1521   else if (parameters->options().relocatable())
1522     load_seg = NULL;
1523   else
1524     load_seg = this->find_first_load_seg();
1525
1526   if (parameters->options().oformat_enum()
1527       != General_options::OBJECT_FORMAT_ELF)
1528     load_seg = NULL;
1529
1530   // If the user set the address of the text segment, that may not be
1531   // compatible with putting the segment headers and file headers into
1532   // that segment.
1533   if (parameters->options().user_set_Ttext())
1534     load_seg = NULL;
1535
1536   gold_assert(phdr_seg == NULL
1537               || load_seg != NULL
1538               || this->script_options_->saw_sections_clause());
1539
1540   // If the address of the load segment we found has been set by
1541   // --section-start rather than by a script, then we don't want to
1542   // use it for the file and segment headers.
1543   if (load_seg != NULL
1544       && load_seg->are_addresses_set()
1545       && !this->script_options_->saw_sections_clause())
1546     load_seg = NULL;
1547
1548   // Lay out the segment headers.
1549   if (!parameters->options().relocatable())
1550     {
1551       gold_assert(segment_headers != NULL);
1552       if (load_seg != NULL)
1553         load_seg->add_initial_output_data(segment_headers);
1554       if (phdr_seg != NULL)
1555         phdr_seg->add_initial_output_data(segment_headers);
1556     }
1557
1558   // Lay out the file header.
1559   if (load_seg != NULL)
1560     load_seg->add_initial_output_data(file_header);
1561
1562   if (this->script_options_->saw_phdrs_clause()
1563       && !parameters->options().relocatable())
1564     {
1565       // Support use of FILEHDRS and PHDRS attachments in a PHDRS
1566       // clause in a linker script.
1567       Script_sections* ss = this->script_options_->script_sections();
1568       ss->put_headers_in_phdrs(file_header, segment_headers);
1569     }
1570
1571   // We set the output section indexes in set_segment_offsets and
1572   // set_section_indexes.
1573   *pshndx = 1;
1574
1575   // Set the file offsets of all the segments, and all the sections
1576   // they contain.
1577   off_t off;
1578   if (!parameters->options().relocatable())
1579     off = this->set_segment_offsets(target, load_seg, pshndx);
1580   else
1581     off = this->set_relocatable_section_offsets(file_header, pshndx);
1582
1583    // Verify that the dummy relaxation does not change anything.
1584   if (is_debugging_enabled(DEBUG_RELAXATION))
1585     {
1586       if (pass == 0)
1587         this->relaxation_debug_check_->read_sections(this->section_list_);
1588       else
1589         this->relaxation_debug_check_->verify_sections(this->section_list_);
1590     }
1591
1592   *pload_seg = load_seg;
1593   return off;
1594 }
1595
1596 // Finalize the layout.  When this is called, we have created all the
1597 // output sections and all the output segments which are based on
1598 // input sections.  We have several things to do, and we have to do
1599 // them in the right order, so that we get the right results correctly
1600 // and efficiently.
1601
1602 // 1) Finalize the list of output segments and create the segment
1603 // table header.
1604
1605 // 2) Finalize the dynamic symbol table and associated sections.
1606
1607 // 3) Determine the final file offset of all the output segments.
1608
1609 // 4) Determine the final file offset of all the SHF_ALLOC output
1610 // sections.
1611
1612 // 5) Create the symbol table sections and the section name table
1613 // section.
1614
1615 // 6) Finalize the symbol table: set symbol values to their final
1616 // value and make a final determination of which symbols are going
1617 // into the output symbol table.
1618
1619 // 7) Create the section table header.
1620
1621 // 8) Determine the final file offset of all the output sections which
1622 // are not SHF_ALLOC, including the section table header.
1623
1624 // 9) Finalize the ELF file header.
1625
1626 // This function returns the size of the output file.
1627
1628 off_t
1629 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab,
1630                  Target* target, const Task* task)
1631 {
1632   target->finalize_sections(this, input_objects, symtab);
1633
1634   this->count_local_symbols(task, input_objects);
1635
1636   this->link_stabs_sections();
1637
1638   Output_segment* phdr_seg = NULL;
1639   if (!parameters->options().relocatable() && !parameters->doing_static_link())
1640     {
1641       // There was a dynamic object in the link.  We need to create
1642       // some information for the dynamic linker.
1643
1644       // Create the PT_PHDR segment which will hold the program
1645       // headers.
1646       if (!this->script_options_->saw_phdrs_clause())
1647         phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R);
1648
1649       // Create the dynamic symbol table, including the hash table.
1650       Output_section* dynstr;
1651       std::vector<Symbol*> dynamic_symbols;
1652       unsigned int local_dynamic_count;
1653       Versions versions(*this->script_options()->version_script_info(),
1654                         &this->dynpool_);
1655       this->create_dynamic_symtab(input_objects, symtab, &dynstr,
1656                                   &local_dynamic_count, &dynamic_symbols,
1657                                   &versions);
1658
1659       // Create the .interp section to hold the name of the
1660       // interpreter, and put it in a PT_INTERP segment.
1661       if (!parameters->options().shared())
1662         this->create_interp(target);
1663
1664       // Finish the .dynamic section to hold the dynamic data, and put
1665       // it in a PT_DYNAMIC segment.
1666       this->finish_dynamic_section(input_objects, symtab);
1667
1668       // We should have added everything we need to the dynamic string
1669       // table.
1670       this->dynpool_.set_string_offsets();
1671
1672       // Create the version sections.  We can't do this until the
1673       // dynamic string table is complete.
1674       this->create_version_sections(&versions, symtab, local_dynamic_count,
1675                                     dynamic_symbols, dynstr);
1676
1677       // Set the size of the _DYNAMIC symbol.  We can't do this until
1678       // after we call create_version_sections.
1679       this->set_dynamic_symbol_size(symtab);
1680     }
1681
1682   if (this->incremental_inputs_)
1683     {
1684       this->incremental_inputs_->finalize();
1685       this->create_incremental_info_sections();
1686     }
1687
1688   // Create segment headers.
1689   Output_segment_headers* segment_headers =
1690     (parameters->options().relocatable()
1691      ? NULL
1692      : new Output_segment_headers(this->segment_list_));
1693
1694   // Lay out the file header.
1695   Output_file_header* file_header
1696     = new Output_file_header(target, symtab, segment_headers,
1697                              parameters->options().entry());
1698
1699   this->special_output_list_.push_back(file_header);
1700   if (segment_headers != NULL)
1701     this->special_output_list_.push_back(segment_headers);
1702
1703   // Find approriate places for orphan output sections if we are using
1704   // a linker script.
1705   if (this->script_options_->saw_sections_clause())
1706     this->place_orphan_sections_in_script();
1707
1708   Output_segment* load_seg;
1709   off_t off;
1710   unsigned int shndx;
1711   int pass = 0;
1712
1713   // Take a snapshot of the section layout as needed.
1714   if (target->may_relax())
1715     this->prepare_for_relaxation();
1716
1717   // Run the relaxation loop to lay out sections.
1718   do
1719     {
1720       off = this->relaxation_loop_body(pass, target, symtab, &load_seg,
1721                                        phdr_seg, segment_headers, file_header,
1722                                        &shndx);
1723       pass++;
1724     }
1725   while (target->may_relax()
1726          && target->relax(pass, input_objects, symtab, this));
1727
1728   // Set the file offsets of all the non-data sections we've seen so
1729   // far which don't have to wait for the input sections.  We need
1730   // this in order to finalize local symbols in non-allocated
1731   // sections.
1732   off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
1733
1734   // Set the section indexes of all unallocated sections seen so far,
1735   // in case any of them are somehow referenced by a symbol.
1736   shndx = this->set_section_indexes(shndx);
1737
1738   // Create the symbol table sections.
1739   this->create_symtab_sections(input_objects, symtab, shndx, &off);
1740   if (!parameters->doing_static_link())
1741     this->assign_local_dynsym_offsets(input_objects);
1742
1743   // Process any symbol assignments from a linker script.  This must
1744   // be called after the symbol table has been finalized.
1745   this->script_options_->finalize_symbols(symtab, this);
1746
1747   // Create the .shstrtab section.
1748   Output_section* shstrtab_section = this->create_shstrtab();
1749
1750   // Set the file offsets of the rest of the non-data sections which
1751   // don't have to wait for the input sections.
1752   off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS);
1753
1754   // Now that all sections have been created, set the section indexes
1755   // for any sections which haven't been done yet.
1756   shndx = this->set_section_indexes(shndx);
1757
1758   // Create the section table header.
1759   this->create_shdrs(shstrtab_section, &off);
1760
1761   // If there are no sections which require postprocessing, we can
1762   // handle the section names now, and avoid a resize later.
1763   if (!this->any_postprocessing_sections_)
1764     off = this->set_section_offsets(off,
1765                                     STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
1766
1767   file_header->set_section_info(this->section_headers_, shstrtab_section);
1768
1769   // Now we know exactly where everything goes in the output file
1770   // (except for non-allocated sections which require postprocessing).
1771   Output_data::layout_complete();
1772
1773   this->output_file_size_ = off;
1774
1775   return off;
1776 }
1777
1778 // Create a note header following the format defined in the ELF ABI.
1779 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name
1780 // of the section to create, DESCSZ is the size of the descriptor.
1781 // ALLOCATE is true if the section should be allocated in memory.
1782 // This returns the new note section.  It sets *TRAILING_PADDING to
1783 // the number of trailing zero bytes required.
1784
1785 Output_section*
1786 Layout::create_note(const char* name, int note_type,
1787                     const char* section_name, size_t descsz,
1788                     bool allocate, size_t* trailing_padding)
1789 {
1790   // Authorities all agree that the values in a .note field should
1791   // be aligned on 4-byte boundaries for 32-bit binaries.  However,
1792   // they differ on what the alignment is for 64-bit binaries.
1793   // The GABI says unambiguously they take 8-byte alignment:
1794   //    http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section
1795   // Other documentation says alignment should always be 4 bytes:
1796   //    http://www.netbsd.org/docs/kernel/elf-notes.html#note-format
1797   // GNU ld and GNU readelf both support the latter (at least as of
1798   // version 2.16.91), and glibc always generates the latter for
1799   // .note.ABI-tag (as of version 1.6), so that's the one we go with
1800   // here.
1801 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION   // This is not defined by default.
1802   const int size = parameters->target().get_size();
1803 #else
1804   const int size = 32;
1805 #endif
1806
1807   // The contents of the .note section.
1808   size_t namesz = strlen(name) + 1;
1809   size_t aligned_namesz = align_address(namesz, size / 8);
1810   size_t aligned_descsz = align_address(descsz, size / 8);
1811
1812   size_t notehdrsz = 3 * (size / 8) + aligned_namesz;
1813
1814   unsigned char* buffer = new unsigned char[notehdrsz];
1815   memset(buffer, 0, notehdrsz);
1816
1817   bool is_big_endian = parameters->target().is_big_endian();
1818
1819   if (size == 32)
1820     {
1821       if (!is_big_endian)
1822         {
1823           elfcpp::Swap<32, false>::writeval(buffer, namesz);
1824           elfcpp::Swap<32, false>::writeval(buffer + 4, descsz);
1825           elfcpp::Swap<32, false>::writeval(buffer + 8, note_type);
1826         }
1827       else
1828         {
1829           elfcpp::Swap<32, true>::writeval(buffer, namesz);
1830           elfcpp::Swap<32, true>::writeval(buffer + 4, descsz);
1831           elfcpp::Swap<32, true>::writeval(buffer + 8, note_type);
1832         }
1833     }
1834   else if (size == 64)
1835     {
1836       if (!is_big_endian)
1837         {
1838           elfcpp::Swap<64, false>::writeval(buffer, namesz);
1839           elfcpp::Swap<64, false>::writeval(buffer + 8, descsz);
1840           elfcpp::Swap<64, false>::writeval(buffer + 16, note_type);
1841         }
1842       else
1843         {
1844           elfcpp::Swap<64, true>::writeval(buffer, namesz);
1845           elfcpp::Swap<64, true>::writeval(buffer + 8, descsz);
1846           elfcpp::Swap<64, true>::writeval(buffer + 16, note_type);
1847         }
1848     }
1849   else
1850     gold_unreachable();
1851
1852   memcpy(buffer + 3 * (size / 8), name, namesz);
1853
1854   elfcpp::Elf_Xword flags = 0;
1855   if (allocate)
1856     flags = elfcpp::SHF_ALLOC;
1857   Output_section* os = this->choose_output_section(NULL, section_name,
1858                                                    elfcpp::SHT_NOTE,
1859                                                    flags, false, false,
1860                                                    false, false, false, false);
1861   if (os == NULL)
1862     return NULL;
1863
1864   Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz,
1865                                                            size / 8,
1866                                                            "** note header");
1867   os->add_output_section_data(posd);
1868
1869   *trailing_padding = aligned_descsz - descsz;
1870
1871   return os;
1872 }
1873
1874 // For an executable or shared library, create a note to record the
1875 // version of gold used to create the binary.
1876
1877 void
1878 Layout::create_gold_note()
1879 {
1880   if (parameters->options().relocatable())
1881     return;
1882
1883   std::string desc = std::string("gold ") + gold::get_version_string();
1884
1885   size_t trailing_padding;
1886   Output_section *os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION,
1887                                          ".note.gnu.gold-version", desc.size(),
1888                                          false, &trailing_padding);
1889   if (os == NULL)
1890     return;
1891
1892   Output_section_data* posd = new Output_data_const(desc, 4);
1893   os->add_output_section_data(posd);
1894
1895   if (trailing_padding > 0)
1896     {
1897       posd = new Output_data_zero_fill(trailing_padding, 0);
1898       os->add_output_section_data(posd);
1899     }
1900 }
1901
1902 // Record whether the stack should be executable.  This can be set
1903 // from the command line using the -z execstack or -z noexecstack
1904 // options.  Otherwise, if any input file has a .note.GNU-stack
1905 // section with the SHF_EXECINSTR flag set, the stack should be
1906 // executable.  Otherwise, if at least one input file a
1907 // .note.GNU-stack section, and some input file has no .note.GNU-stack
1908 // section, we use the target default for whether the stack should be
1909 // executable.  Otherwise, we don't generate a stack note.  When
1910 // generating a object file, we create a .note.GNU-stack section with
1911 // the appropriate marking.  When generating an executable or shared
1912 // library, we create a PT_GNU_STACK segment.
1913
1914 void
1915 Layout::create_executable_stack_info()
1916 {
1917   bool is_stack_executable;
1918   if (parameters->options().is_execstack_set())
1919     is_stack_executable = parameters->options().is_stack_executable();
1920   else if (!this->input_with_gnu_stack_note_)
1921     return;
1922   else
1923     {
1924       if (this->input_requires_executable_stack_)
1925         is_stack_executable = true;
1926       else if (this->input_without_gnu_stack_note_)
1927         is_stack_executable =
1928           parameters->target().is_default_stack_executable();
1929       else
1930         is_stack_executable = false;
1931     }
1932
1933   if (parameters->options().relocatable())
1934     {
1935       const char* name = this->namepool_.add(".note.GNU-stack", false, NULL);
1936       elfcpp::Elf_Xword flags = 0;
1937       if (is_stack_executable)
1938         flags |= elfcpp::SHF_EXECINSTR;
1939       this->make_output_section(name, elfcpp::SHT_PROGBITS, flags, false,
1940                                 false, false, false, false);
1941     }
1942   else
1943     {
1944       if (this->script_options_->saw_phdrs_clause())
1945         return;
1946       int flags = elfcpp::PF_R | elfcpp::PF_W;
1947       if (is_stack_executable)
1948         flags |= elfcpp::PF_X;
1949       this->make_output_segment(elfcpp::PT_GNU_STACK, flags);
1950     }
1951 }
1952
1953 // If --build-id was used, set up the build ID note.
1954
1955 void
1956 Layout::create_build_id()
1957 {
1958   if (!parameters->options().user_set_build_id())
1959     return;
1960
1961   const char* style = parameters->options().build_id();
1962   if (strcmp(style, "none") == 0)
1963     return;
1964
1965   // Set DESCSZ to the size of the note descriptor.  When possible,
1966   // set DESC to the note descriptor contents.
1967   size_t descsz;
1968   std::string desc;
1969   if (strcmp(style, "md5") == 0)
1970     descsz = 128 / 8;
1971   else if (strcmp(style, "sha1") == 0)
1972     descsz = 160 / 8;
1973   else if (strcmp(style, "uuid") == 0)
1974     {
1975       const size_t uuidsz = 128 / 8;
1976
1977       char buffer[uuidsz];
1978       memset(buffer, 0, uuidsz);
1979
1980       int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY);
1981       if (descriptor < 0)
1982         gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
1983                    strerror(errno));
1984       else
1985         {
1986           ssize_t got = ::read(descriptor, buffer, uuidsz);
1987           release_descriptor(descriptor, true);
1988           if (got < 0)
1989             gold_error(_("/dev/urandom: read failed: %s"), strerror(errno));
1990           else if (static_cast<size_t>(got) != uuidsz)
1991             gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
1992                        uuidsz, got);
1993         }
1994
1995       desc.assign(buffer, uuidsz);
1996       descsz = uuidsz;
1997     }
1998   else if (strncmp(style, "0x", 2) == 0)
1999     {
2000       hex_init();
2001       const char* p = style + 2;
2002       while (*p != '\0')
2003         {
2004           if (hex_p(p[0]) && hex_p(p[1]))
2005             {
2006               char c = (hex_value(p[0]) << 4) | hex_value(p[1]);
2007               desc += c;
2008               p += 2;
2009             }
2010           else if (*p == '-' || *p == ':')
2011             ++p;
2012           else
2013             gold_fatal(_("--build-id argument '%s' not a valid hex number"),
2014                        style);
2015         }
2016       descsz = desc.size();
2017     }
2018   else
2019     gold_fatal(_("unrecognized --build-id argument '%s'"), style);
2020
2021   // Create the note.
2022   size_t trailing_padding;
2023   Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID,
2024                                          ".note.gnu.build-id", descsz, true,
2025                                          &trailing_padding);
2026   if (os == NULL)
2027     return;
2028
2029   if (!desc.empty())
2030     {
2031       // We know the value already, so we fill it in now.
2032       gold_assert(desc.size() == descsz);
2033
2034       Output_section_data* posd = new Output_data_const(desc, 4);
2035       os->add_output_section_data(posd);
2036
2037       if (trailing_padding != 0)
2038         {
2039           posd = new Output_data_zero_fill(trailing_padding, 0);
2040           os->add_output_section_data(posd);
2041         }
2042     }
2043   else
2044     {
2045       // We need to compute a checksum after we have completed the
2046       // link.
2047       gold_assert(trailing_padding == 0);
2048       this->build_id_note_ = new Output_data_zero_fill(descsz, 4);
2049       os->add_output_section_data(this->build_id_note_);
2050     }
2051 }
2052
2053 // If we have both .stabXX and .stabXXstr sections, then the sh_link
2054 // field of the former should point to the latter.  I'm not sure who
2055 // started this, but the GNU linker does it, and some tools depend
2056 // upon it.
2057
2058 void
2059 Layout::link_stabs_sections()
2060 {
2061   if (!this->have_stabstr_section_)
2062     return;
2063
2064   for (Section_list::iterator p = this->section_list_.begin();
2065        p != this->section_list_.end();
2066        ++p)
2067     {
2068       if ((*p)->type() != elfcpp::SHT_STRTAB)
2069         continue;
2070
2071       const char* name = (*p)->name();
2072       if (strncmp(name, ".stab", 5) != 0)
2073         continue;
2074
2075       size_t len = strlen(name);
2076       if (strcmp(name + len - 3, "str") != 0)
2077         continue;
2078
2079       std::string stab_name(name, len - 3);
2080       Output_section* stab_sec;
2081       stab_sec = this->find_output_section(stab_name.c_str());
2082       if (stab_sec != NULL)
2083         stab_sec->set_link_section(*p);
2084     }
2085 }
2086
2087 // Create .gnu_incremental_inputs and .gnu_incremental_strtab sections needed
2088 // for the next run of incremental linking to check what has changed.
2089
2090 void
2091 Layout::create_incremental_info_sections()
2092 {
2093   gold_assert(this->incremental_inputs_ != NULL);
2094
2095   // Add the .gnu_incremental_inputs section.
2096   const char *incremental_inputs_name =
2097     this->namepool_.add(".gnu_incremental_inputs", false, NULL);
2098   Output_section* inputs_os =
2099     this->make_output_section(incremental_inputs_name,
2100                               elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0,
2101                               false, false, false, false, false);
2102   Output_section_data* posd =
2103       this->incremental_inputs_->create_incremental_inputs_section_data();
2104   inputs_os->add_output_section_data(posd);
2105
2106   // Add the .gnu_incremental_strtab section.
2107   const char *incremental_strtab_name =
2108     this->namepool_.add(".gnu_incremental_strtab", false, NULL);
2109   Output_section* strtab_os = this->make_output_section(incremental_strtab_name,
2110                                                         elfcpp::SHT_STRTAB,
2111                                                         0, false, false,
2112                                                         false, false, false);
2113   Output_data_strtab* strtab_data =
2114     new Output_data_strtab(this->incremental_inputs_->get_stringpool());
2115   strtab_os->add_output_section_data(strtab_data);
2116
2117   inputs_os->set_link_section(strtab_data);
2118 }
2119
2120 // Return whether SEG1 should be before SEG2 in the output file.  This
2121 // is based entirely on the segment type and flags.  When this is
2122 // called the segment addresses has normally not yet been set.
2123
2124 bool
2125 Layout::segment_precedes(const Output_segment* seg1,
2126                          const Output_segment* seg2)
2127 {
2128   elfcpp::Elf_Word type1 = seg1->type();
2129   elfcpp::Elf_Word type2 = seg2->type();
2130
2131   // The single PT_PHDR segment is required to precede any loadable
2132   // segment.  We simply make it always first.
2133   if (type1 == elfcpp::PT_PHDR)
2134     {
2135       gold_assert(type2 != elfcpp::PT_PHDR);
2136       return true;
2137     }
2138   if (type2 == elfcpp::PT_PHDR)
2139     return false;
2140
2141   // The single PT_INTERP segment is required to precede any loadable
2142   // segment.  We simply make it always second.
2143   if (type1 == elfcpp::PT_INTERP)
2144     {
2145       gold_assert(type2 != elfcpp::PT_INTERP);
2146       return true;
2147     }
2148   if (type2 == elfcpp::PT_INTERP)
2149     return false;
2150
2151   // We then put PT_LOAD segments before any other segments.
2152   if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
2153     return true;
2154   if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
2155     return false;
2156
2157   // We put the PT_TLS segment last except for the PT_GNU_RELRO
2158   // segment, because that is where the dynamic linker expects to find
2159   // it (this is just for efficiency; other positions would also work
2160   // correctly).
2161   if (type1 == elfcpp::PT_TLS
2162       && type2 != elfcpp::PT_TLS
2163       && type2 != elfcpp::PT_GNU_RELRO)
2164     return false;
2165   if (type2 == elfcpp::PT_TLS
2166       && type1 != elfcpp::PT_TLS
2167       && type1 != elfcpp::PT_GNU_RELRO)
2168     return true;
2169
2170   // We put the PT_GNU_RELRO segment last, because that is where the
2171   // dynamic linker expects to find it (as with PT_TLS, this is just
2172   // for efficiency).
2173   if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO)
2174     return false;
2175   if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO)
2176     return true;
2177
2178   const elfcpp::Elf_Word flags1 = seg1->flags();
2179   const elfcpp::Elf_Word flags2 = seg2->flags();
2180
2181   // The order of non-PT_LOAD segments is unimportant.  We simply sort
2182   // by the numeric segment type and flags values.  There should not
2183   // be more than one segment with the same type and flags.
2184   if (type1 != elfcpp::PT_LOAD)
2185     {
2186       if (type1 != type2)
2187         return type1 < type2;
2188       gold_assert(flags1 != flags2);
2189       return flags1 < flags2;
2190     }
2191
2192   // If the addresses are set already, sort by load address.
2193   if (seg1->are_addresses_set())
2194     {
2195       if (!seg2->are_addresses_set())
2196         return true;
2197
2198       unsigned int section_count1 = seg1->output_section_count();
2199       unsigned int section_count2 = seg2->output_section_count();
2200       if (section_count1 == 0 && section_count2 > 0)
2201         return true;
2202       if (section_count1 > 0 && section_count2 == 0)
2203         return false;
2204
2205       uint64_t paddr1 = seg1->first_section_load_address();
2206       uint64_t paddr2 = seg2->first_section_load_address();
2207       if (paddr1 != paddr2)
2208         return paddr1 < paddr2;
2209     }
2210   else if (seg2->are_addresses_set())
2211     return false;
2212
2213   // A segment which holds large data comes after a segment which does
2214   // not hold large data.
2215   if (seg1->is_large_data_segment())
2216     {
2217       if (!seg2->is_large_data_segment())
2218         return false;
2219     }
2220   else if (seg2->is_large_data_segment())
2221     return true;
2222
2223   // Otherwise, we sort PT_LOAD segments based on the flags.  Readonly
2224   // segments come before writable segments.  Then writable segments
2225   // with data come before writable segments without data.  Then
2226   // executable segments come before non-executable segments.  Then
2227   // the unlikely case of a non-readable segment comes before the
2228   // normal case of a readable segment.  If there are multiple
2229   // segments with the same type and flags, we require that the
2230   // address be set, and we sort by virtual address and then physical
2231   // address.
2232   if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
2233     return (flags1 & elfcpp::PF_W) == 0;
2234   if ((flags1 & elfcpp::PF_W) != 0
2235       && seg1->has_any_data_sections() != seg2->has_any_data_sections())
2236     return seg1->has_any_data_sections();
2237   if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
2238     return (flags1 & elfcpp::PF_X) != 0;
2239   if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
2240     return (flags1 & elfcpp::PF_R) == 0;
2241
2242   // We shouldn't get here--we shouldn't create segments which we
2243   // can't distinguish.
2244   gold_unreachable();
2245 }
2246
2247 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE.
2248
2249 static off_t
2250 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize)
2251 {
2252   uint64_t unsigned_off = off;
2253   uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1))
2254                           | (addr & (abi_pagesize - 1)));
2255   if (aligned_off < unsigned_off)
2256     aligned_off += abi_pagesize;
2257   return aligned_off;
2258 }
2259
2260 // Set the file offsets of all the segments, and all the sections they
2261 // contain.  They have all been created.  LOAD_SEG must be be laid out
2262 // first.  Return the offset of the data to follow.
2263
2264 off_t
2265 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg,
2266                             unsigned int *pshndx)
2267 {
2268   // Sort them into the final order.
2269   std::sort(this->segment_list_.begin(), this->segment_list_.end(),
2270             Layout::Compare_segments());
2271
2272   // Find the PT_LOAD segments, and set their addresses and offsets
2273   // and their section's addresses and offsets.
2274   uint64_t addr;
2275   if (parameters->options().user_set_Ttext())
2276     addr = parameters->options().Ttext();
2277   else if (parameters->options().output_is_position_independent())
2278     addr = 0;
2279   else
2280     addr = target->default_text_segment_address();
2281   off_t off = 0;
2282
2283   // If LOAD_SEG is NULL, then the file header and segment headers
2284   // will not be loadable.  But they still need to be at offset 0 in
2285   // the file.  Set their offsets now.
2286   if (load_seg == NULL)
2287     {
2288       for (Data_list::iterator p = this->special_output_list_.begin();
2289            p != this->special_output_list_.end();
2290            ++p)
2291         {
2292           off = align_address(off, (*p)->addralign());
2293           (*p)->set_address_and_file_offset(0, off);
2294           off += (*p)->data_size();
2295         }
2296     }
2297
2298   unsigned int increase_relro = this->increase_relro_;
2299   if (this->script_options_->saw_sections_clause())
2300     increase_relro = 0;
2301
2302   const bool check_sections = parameters->options().check_sections();
2303   Output_segment* last_load_segment = NULL;
2304
2305   bool was_readonly = false;
2306   for (Segment_list::iterator p = this->segment_list_.begin();
2307        p != this->segment_list_.end();
2308        ++p)
2309     {
2310       if ((*p)->type() == elfcpp::PT_LOAD)
2311         {
2312           if (load_seg != NULL && load_seg != *p)
2313             gold_unreachable();
2314           load_seg = NULL;
2315
2316           bool are_addresses_set = (*p)->are_addresses_set();
2317           if (are_addresses_set)
2318             {
2319               // When it comes to setting file offsets, we care about
2320               // the physical address.
2321               addr = (*p)->paddr();
2322             }
2323           else if (parameters->options().user_set_Tdata()
2324                    && ((*p)->flags() & elfcpp::PF_W) != 0
2325                    && (!parameters->options().user_set_Tbss()
2326                        || (*p)->has_any_data_sections()))
2327             {
2328               addr = parameters->options().Tdata();
2329               are_addresses_set = true;
2330             }
2331           else if (parameters->options().user_set_Tbss()
2332                    && ((*p)->flags() & elfcpp::PF_W) != 0
2333                    && !(*p)->has_any_data_sections())
2334             {
2335               addr = parameters->options().Tbss();
2336               are_addresses_set = true;
2337             }
2338
2339           uint64_t orig_addr = addr;
2340           uint64_t orig_off = off;
2341
2342           uint64_t aligned_addr = 0;
2343           uint64_t abi_pagesize = target->abi_pagesize();
2344           uint64_t common_pagesize = target->common_pagesize();
2345
2346           if (!parameters->options().nmagic()
2347               && !parameters->options().omagic())
2348             (*p)->set_minimum_p_align(common_pagesize);
2349
2350           if (!are_addresses_set)
2351             {
2352               // If the last segment was readonly, and this one is
2353               // not, then skip the address forward one page,
2354               // maintaining the same position within the page.  This
2355               // lets us store both segments overlapping on a single
2356               // page in the file, but the loader will put them on
2357               // different pages in memory.
2358
2359               addr = align_address(addr, (*p)->maximum_alignment());
2360               aligned_addr = addr;
2361
2362               if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0)
2363                 {
2364                   if ((addr & (abi_pagesize - 1)) != 0)
2365                     addr = addr + abi_pagesize;
2366                 }
2367
2368               off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
2369             }
2370
2371           if (!parameters->options().nmagic()
2372               && !parameters->options().omagic())
2373             off = align_file_offset(off, addr, abi_pagesize);
2374           else if (load_seg == NULL)
2375             {
2376               // This is -N or -n with a section script which prevents
2377               // us from using a load segment.  We need to ensure that
2378               // the file offset is aligned to the alignment of the
2379               // segment.  This is because the linker script
2380               // implicitly assumed a zero offset.  If we don't align
2381               // here, then the alignment of the sections in the
2382               // linker script may not match the alignment of the
2383               // sections in the set_section_addresses call below,
2384               // causing an error about dot moving backward.
2385               off = align_address(off, (*p)->maximum_alignment());
2386             }
2387
2388           unsigned int shndx_hold = *pshndx;
2389           uint64_t new_addr = (*p)->set_section_addresses(this, false, addr,
2390                                                           increase_relro,
2391                                                           &off, pshndx);
2392
2393           // Now that we know the size of this segment, we may be able
2394           // to save a page in memory, at the cost of wasting some
2395           // file space, by instead aligning to the start of a new
2396           // page.  Here we use the real machine page size rather than
2397           // the ABI mandated page size.
2398
2399           if (!are_addresses_set && aligned_addr != addr)
2400             {
2401               uint64_t first_off = (common_pagesize
2402                                     - (aligned_addr
2403                                        & (common_pagesize - 1)));
2404               uint64_t last_off = new_addr & (common_pagesize - 1);
2405               if (first_off > 0
2406                   && last_off > 0
2407                   && ((aligned_addr & ~ (common_pagesize - 1))
2408                       != (new_addr & ~ (common_pagesize - 1)))
2409                   && first_off + last_off <= common_pagesize)
2410                 {
2411                   *pshndx = shndx_hold;
2412                   addr = align_address(aligned_addr, common_pagesize);
2413                   addr = align_address(addr, (*p)->maximum_alignment());
2414                   off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
2415                   off = align_file_offset(off, addr, abi_pagesize);
2416                   new_addr = (*p)->set_section_addresses(this, true, addr,
2417                                                          increase_relro,
2418                                                          &off, pshndx);
2419                 }
2420             }
2421
2422           addr = new_addr;
2423
2424           if (((*p)->flags() & elfcpp::PF_W) == 0)
2425             was_readonly = true;
2426
2427           // Implement --check-sections.  We know that the segments
2428           // are sorted by LMA.
2429           if (check_sections && last_load_segment != NULL)
2430             {
2431               gold_assert(last_load_segment->paddr() <= (*p)->paddr());
2432               if (last_load_segment->paddr() + last_load_segment->memsz()
2433                   > (*p)->paddr())
2434                 {
2435                   unsigned long long lb1 = last_load_segment->paddr();
2436                   unsigned long long le1 = lb1 + last_load_segment->memsz();
2437                   unsigned long long lb2 = (*p)->paddr();
2438                   unsigned long long le2 = lb2 + (*p)->memsz();
2439                   gold_error(_("load segment overlap [0x%llx -> 0x%llx] and "
2440                                "[0x%llx -> 0x%llx]"),
2441                              lb1, le1, lb2, le2);
2442                 }
2443             }
2444           last_load_segment = *p;
2445         }
2446     }
2447
2448   // Handle the non-PT_LOAD segments, setting their offsets from their
2449   // section's offsets.
2450   for (Segment_list::iterator p = this->segment_list_.begin();
2451        p != this->segment_list_.end();
2452        ++p)
2453     {
2454       if ((*p)->type() != elfcpp::PT_LOAD)
2455         (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO
2456                          ? increase_relro
2457                          : 0);
2458     }
2459
2460   // Set the TLS offsets for each section in the PT_TLS segment.
2461   if (this->tls_segment_ != NULL)
2462     this->tls_segment_->set_tls_offsets();
2463
2464   return off;
2465 }
2466
2467 // Set the offsets of all the allocated sections when doing a
2468 // relocatable link.  This does the same jobs as set_segment_offsets,
2469 // only for a relocatable link.
2470
2471 off_t
2472 Layout::set_relocatable_section_offsets(Output_data* file_header,
2473                                         unsigned int *pshndx)
2474 {
2475   off_t off = 0;
2476
2477   file_header->set_address_and_file_offset(0, 0);
2478   off += file_header->data_size();
2479
2480   for (Section_list::iterator p = this->section_list_.begin();
2481        p != this->section_list_.end();
2482        ++p)
2483     {
2484       // We skip unallocated sections here, except that group sections
2485       // have to come first.
2486       if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0
2487           && (*p)->type() != elfcpp::SHT_GROUP)
2488         continue;
2489
2490       off = align_address(off, (*p)->addralign());
2491
2492       // The linker script might have set the address.
2493       if (!(*p)->is_address_valid())
2494         (*p)->set_address(0);
2495       (*p)->set_file_offset(off);
2496       (*p)->finalize_data_size();
2497       off += (*p)->data_size();
2498
2499       (*p)->set_out_shndx(*pshndx);
2500       ++*pshndx;
2501     }
2502
2503   return off;
2504 }
2505
2506 // Set the file offset of all the sections not associated with a
2507 // segment.
2508
2509 off_t
2510 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass)
2511 {
2512   for (Section_list::iterator p = this->unattached_section_list_.begin();
2513        p != this->unattached_section_list_.end();
2514        ++p)
2515     {
2516       // The symtab section is handled in create_symtab_sections.
2517       if (*p == this->symtab_section_)
2518         continue;
2519
2520       // If we've already set the data size, don't set it again.
2521       if ((*p)->is_offset_valid() && (*p)->is_data_size_valid())
2522         continue;
2523
2524       if (pass == BEFORE_INPUT_SECTIONS_PASS
2525           && (*p)->requires_postprocessing())
2526         {
2527           (*p)->create_postprocessing_buffer();
2528           this->any_postprocessing_sections_ = true;
2529         }
2530
2531       if (pass == BEFORE_INPUT_SECTIONS_PASS
2532           && (*p)->after_input_sections())
2533         continue;
2534       else if (pass == POSTPROCESSING_SECTIONS_PASS
2535                && (!(*p)->after_input_sections()
2536                    || (*p)->type() == elfcpp::SHT_STRTAB))
2537         continue;
2538       else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS
2539                && (!(*p)->after_input_sections()
2540                    || (*p)->type() != elfcpp::SHT_STRTAB))
2541         continue;
2542
2543       off = align_address(off, (*p)->addralign());
2544       (*p)->set_file_offset(off);
2545       (*p)->finalize_data_size();
2546       off += (*p)->data_size();
2547
2548       // At this point the name must be set.
2549       if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS)
2550         this->namepool_.add((*p)->name(), false, NULL);
2551     }
2552   return off;
2553 }
2554
2555 // Set the section indexes of all the sections not associated with a
2556 // segment.
2557
2558 unsigned int
2559 Layout::set_section_indexes(unsigned int shndx)
2560 {
2561   for (Section_list::iterator p = this->unattached_section_list_.begin();
2562        p != this->unattached_section_list_.end();
2563        ++p)
2564     {
2565       if (!(*p)->has_out_shndx())
2566         {
2567           (*p)->set_out_shndx(shndx);
2568           ++shndx;
2569         }
2570     }
2571   return shndx;
2572 }
2573
2574 // Set the section addresses according to the linker script.  This is
2575 // only called when we see a SECTIONS clause.  This returns the
2576 // program segment which should hold the file header and segment
2577 // headers, if any.  It will return NULL if they should not be in a
2578 // segment.
2579
2580 Output_segment*
2581 Layout::set_section_addresses_from_script(Symbol_table* symtab)
2582 {
2583   Script_sections* ss = this->script_options_->script_sections();
2584   gold_assert(ss->saw_sections_clause());
2585   return this->script_options_->set_section_addresses(symtab, this);
2586 }
2587
2588 // Place the orphan sections in the linker script.
2589
2590 void
2591 Layout::place_orphan_sections_in_script()
2592 {
2593   Script_sections* ss = this->script_options_->script_sections();
2594   gold_assert(ss->saw_sections_clause());
2595
2596   // Place each orphaned output section in the script.
2597   for (Section_list::iterator p = this->section_list_.begin();
2598        p != this->section_list_.end();
2599        ++p)
2600     {
2601       if (!(*p)->found_in_sections_clause())
2602         ss->place_orphan(*p);
2603     }
2604 }
2605
2606 // Count the local symbols in the regular symbol table and the dynamic
2607 // symbol table, and build the respective string pools.
2608
2609 void
2610 Layout::count_local_symbols(const Task* task,
2611                             const Input_objects* input_objects)
2612 {
2613   // First, figure out an upper bound on the number of symbols we'll
2614   // be inserting into each pool.  This helps us create the pools with
2615   // the right size, to avoid unnecessary hashtable resizing.
2616   unsigned int symbol_count = 0;
2617   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
2618        p != input_objects->relobj_end();
2619        ++p)
2620     symbol_count += (*p)->local_symbol_count();
2621
2622   // Go from "upper bound" to "estimate."  We overcount for two
2623   // reasons: we double-count symbols that occur in more than one
2624   // object file, and we count symbols that are dropped from the
2625   // output.  Add it all together and assume we overcount by 100%.
2626   symbol_count /= 2;
2627
2628   // We assume all symbols will go into both the sympool and dynpool.
2629   this->sympool_.reserve(symbol_count);
2630   this->dynpool_.reserve(symbol_count);
2631
2632   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
2633        p != input_objects->relobj_end();
2634        ++p)
2635     {
2636       Task_lock_obj<Object> tlo(task, *p);
2637       (*p)->count_local_symbols(&this->sympool_, &this->dynpool_);
2638     }
2639 }
2640
2641 // Create the symbol table sections.  Here we also set the final
2642 // values of the symbols.  At this point all the loadable sections are
2643 // fully laid out.  SHNUM is the number of sections so far.
2644
2645 void
2646 Layout::create_symtab_sections(const Input_objects* input_objects,
2647                                Symbol_table* symtab,
2648                                unsigned int shnum,
2649                                off_t* poff)
2650 {
2651   int symsize;
2652   unsigned int align;
2653   if (parameters->target().get_size() == 32)
2654     {
2655       symsize = elfcpp::Elf_sizes<32>::sym_size;
2656       align = 4;
2657     }
2658   else if (parameters->target().get_size() == 64)
2659     {
2660       symsize = elfcpp::Elf_sizes<64>::sym_size;
2661       align = 8;
2662     }
2663   else
2664     gold_unreachable();
2665
2666   off_t off = *poff;
2667   off = align_address(off, align);
2668   off_t startoff = off;
2669
2670   // Save space for the dummy symbol at the start of the section.  We
2671   // never bother to write this out--it will just be left as zero.
2672   off += symsize;
2673   unsigned int local_symbol_index = 1;
2674
2675   // Add STT_SECTION symbols for each Output section which needs one.
2676   for (Section_list::iterator p = this->section_list_.begin();
2677        p != this->section_list_.end();
2678        ++p)
2679     {
2680       if (!(*p)->needs_symtab_index())
2681         (*p)->set_symtab_index(-1U);
2682       else
2683         {
2684           (*p)->set_symtab_index(local_symbol_index);
2685           ++local_symbol_index;
2686           off += symsize;
2687         }
2688     }
2689
2690   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
2691        p != input_objects->relobj_end();
2692        ++p)
2693     {
2694       unsigned int index = (*p)->finalize_local_symbols(local_symbol_index,
2695                                                         off, symtab);
2696       off += (index - local_symbol_index) * symsize;
2697       local_symbol_index = index;
2698     }
2699
2700   unsigned int local_symcount = local_symbol_index;
2701   gold_assert(static_cast<off_t>(local_symcount * symsize) == off - startoff);
2702
2703   off_t dynoff;
2704   size_t dyn_global_index;
2705   size_t dyncount;
2706   if (this->dynsym_section_ == NULL)
2707     {
2708       dynoff = 0;
2709       dyn_global_index = 0;
2710       dyncount = 0;
2711     }
2712   else
2713     {
2714       dyn_global_index = this->dynsym_section_->info();
2715       off_t locsize = dyn_global_index * this->dynsym_section_->entsize();
2716       dynoff = this->dynsym_section_->offset() + locsize;
2717       dyncount = (this->dynsym_section_->data_size() - locsize) / symsize;
2718       gold_assert(static_cast<off_t>(dyncount * symsize)
2719                   == this->dynsym_section_->data_size() - locsize);
2720     }
2721
2722   off = symtab->finalize(off, dynoff, dyn_global_index, dyncount,
2723                          &this->sympool_, &local_symcount);
2724
2725   if (!parameters->options().strip_all())
2726     {
2727       this->sympool_.set_string_offsets();
2728
2729       const char* symtab_name = this->namepool_.add(".symtab", false, NULL);
2730       Output_section* osymtab = this->make_output_section(symtab_name,
2731                                                           elfcpp::SHT_SYMTAB,
2732                                                           0, false, false,
2733                                                           false, false, false);
2734       this->symtab_section_ = osymtab;
2735
2736       Output_section_data* pos = new Output_data_fixed_space(off - startoff,
2737                                                              align,
2738                                                              "** symtab");
2739       osymtab->add_output_section_data(pos);
2740
2741       // We generate a .symtab_shndx section if we have more than
2742       // SHN_LORESERVE sections.  Technically it is possible that we
2743       // don't need one, because it is possible that there are no
2744       // symbols in any of sections with indexes larger than
2745       // SHN_LORESERVE.  That is probably unusual, though, and it is
2746       // easier to always create one than to compute section indexes
2747       // twice (once here, once when writing out the symbols).
2748       if (shnum >= elfcpp::SHN_LORESERVE)
2749         {
2750           const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx",
2751                                                                false, NULL);
2752           Output_section* osymtab_xindex =
2753             this->make_output_section(symtab_xindex_name,
2754                                       elfcpp::SHT_SYMTAB_SHNDX, 0, false,
2755                                       false, false, false, false);
2756
2757           size_t symcount = (off - startoff) / symsize;
2758           this->symtab_xindex_ = new Output_symtab_xindex(symcount);
2759
2760           osymtab_xindex->add_output_section_data(this->symtab_xindex_);
2761
2762           osymtab_xindex->set_link_section(osymtab);
2763           osymtab_xindex->set_addralign(4);
2764           osymtab_xindex->set_entsize(4);
2765
2766           osymtab_xindex->set_after_input_sections();
2767
2768           // This tells the driver code to wait until the symbol table
2769           // has written out before writing out the postprocessing
2770           // sections, including the .symtab_shndx section.
2771           this->any_postprocessing_sections_ = true;
2772         }
2773
2774       const char* strtab_name = this->namepool_.add(".strtab", false, NULL);
2775       Output_section* ostrtab = this->make_output_section(strtab_name,
2776                                                           elfcpp::SHT_STRTAB,
2777                                                           0, false, false,
2778                                                           false, false, false);
2779
2780       Output_section_data* pstr = new Output_data_strtab(&this->sympool_);
2781       ostrtab->add_output_section_data(pstr);
2782
2783       osymtab->set_file_offset(startoff);
2784       osymtab->finalize_data_size();
2785       osymtab->set_link_section(ostrtab);
2786       osymtab->set_info(local_symcount);
2787       osymtab->set_entsize(symsize);
2788
2789       *poff = off;
2790     }
2791 }
2792
2793 // Create the .shstrtab section, which holds the names of the
2794 // sections.  At the time this is called, we have created all the
2795 // output sections except .shstrtab itself.
2796
2797 Output_section*
2798 Layout::create_shstrtab()
2799 {
2800   // FIXME: We don't need to create a .shstrtab section if we are
2801   // stripping everything.
2802
2803   const char* name = this->namepool_.add(".shstrtab", false, NULL);
2804
2805   Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0,
2806                                                  false, false, false, false,
2807                                                  false);
2808
2809   if (strcmp(parameters->options().compress_debug_sections(), "none") != 0)
2810     {
2811       // We can't write out this section until we've set all the
2812       // section names, and we don't set the names of compressed
2813       // output sections until relocations are complete.  FIXME: With
2814       // the current names we use, this is unnecessary.
2815       os->set_after_input_sections();
2816     }
2817
2818   Output_section_data* posd = new Output_data_strtab(&this->namepool_);
2819   os->add_output_section_data(posd);
2820
2821   return os;
2822 }
2823
2824 // Create the section headers.  SIZE is 32 or 64.  OFF is the file
2825 // offset.
2826
2827 void
2828 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff)
2829 {
2830   Output_section_headers* oshdrs;
2831   oshdrs = new Output_section_headers(this,
2832                                       &this->segment_list_,
2833                                       &this->section_list_,
2834                                       &this->unattached_section_list_,
2835                                       &this->namepool_,
2836                                       shstrtab_section);
2837   off_t off = align_address(*poff, oshdrs->addralign());
2838   oshdrs->set_address_and_file_offset(0, off);
2839   off += oshdrs->data_size();
2840   *poff = off;
2841   this->section_headers_ = oshdrs;
2842 }
2843
2844 // Count the allocated sections.
2845
2846 size_t
2847 Layout::allocated_output_section_count() const
2848 {
2849   size_t section_count = 0;
2850   for (Segment_list::const_iterator p = this->segment_list_.begin();
2851        p != this->segment_list_.end();
2852        ++p)
2853     section_count += (*p)->output_section_count();
2854   return section_count;
2855 }
2856
2857 // Create the dynamic symbol table.
2858
2859 void
2860 Layout::create_dynamic_symtab(const Input_objects* input_objects,
2861                               Symbol_table* symtab,
2862                               Output_section **pdynstr,
2863                               unsigned int* plocal_dynamic_count,
2864                               std::vector<Symbol*>* pdynamic_symbols,
2865                               Versions* pversions)
2866 {
2867   // Count all the symbols in the dynamic symbol table, and set the
2868   // dynamic symbol indexes.
2869
2870   // Skip symbol 0, which is always all zeroes.
2871   unsigned int index = 1;
2872
2873   // Add STT_SECTION symbols for each Output section which needs one.
2874   for (Section_list::iterator p = this->section_list_.begin();
2875        p != this->section_list_.end();
2876        ++p)
2877     {
2878       if (!(*p)->needs_dynsym_index())
2879         (*p)->set_dynsym_index(-1U);
2880       else
2881         {
2882           (*p)->set_dynsym_index(index);
2883           ++index;
2884         }
2885     }
2886
2887   // Count the local symbols that need to go in the dynamic symbol table,
2888   // and set the dynamic symbol indexes.
2889   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
2890        p != input_objects->relobj_end();
2891        ++p)
2892     {
2893       unsigned int new_index = (*p)->set_local_dynsym_indexes(index);
2894       index = new_index;
2895     }
2896
2897   unsigned int local_symcount = index;
2898   *plocal_dynamic_count = local_symcount;
2899
2900   index = symtab->set_dynsym_indexes(index, pdynamic_symbols,
2901                                      &this->dynpool_, pversions);
2902
2903   int symsize;
2904   unsigned int align;
2905   const int size = parameters->target().get_size();
2906   if (size == 32)
2907     {
2908       symsize = elfcpp::Elf_sizes<32>::sym_size;
2909       align = 4;
2910     }
2911   else if (size == 64)
2912     {
2913       symsize = elfcpp::Elf_sizes<64>::sym_size;
2914       align = 8;
2915     }
2916   else
2917     gold_unreachable();
2918
2919   // Create the dynamic symbol table section.
2920
2921   Output_section* dynsym = this->choose_output_section(NULL, ".dynsym",
2922                                                        elfcpp::SHT_DYNSYM,
2923                                                        elfcpp::SHF_ALLOC,
2924                                                        false, false, true,
2925                                                        false, false, false);
2926
2927   Output_section_data* odata = new Output_data_fixed_space(index * symsize,
2928                                                            align,
2929                                                            "** dynsym");
2930   dynsym->add_output_section_data(odata);
2931
2932   dynsym->set_info(local_symcount);
2933   dynsym->set_entsize(symsize);
2934   dynsym->set_addralign(align);
2935
2936   this->dynsym_section_ = dynsym;
2937
2938   Output_data_dynamic* const odyn = this->dynamic_data_;
2939   odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym);
2940   odyn->add_constant(elfcpp::DT_SYMENT, symsize);
2941
2942   // If there are more than SHN_LORESERVE allocated sections, we
2943   // create a .dynsym_shndx section.  It is possible that we don't
2944   // need one, because it is possible that there are no dynamic
2945   // symbols in any of the sections with indexes larger than
2946   // SHN_LORESERVE.  This is probably unusual, though, and at this
2947   // time we don't know the actual section indexes so it is
2948   // inconvenient to check.
2949   if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE)
2950     {
2951       Output_section* dynsym_xindex =
2952         this->choose_output_section(NULL, ".dynsym_shndx",
2953                                     elfcpp::SHT_SYMTAB_SHNDX,
2954                                     elfcpp::SHF_ALLOC,
2955                                     false, false, true, false, false, false);
2956
2957       this->dynsym_xindex_ = new Output_symtab_xindex(index);
2958
2959       dynsym_xindex->add_output_section_data(this->dynsym_xindex_);
2960
2961       dynsym_xindex->set_link_section(dynsym);
2962       dynsym_xindex->set_addralign(4);
2963       dynsym_xindex->set_entsize(4);
2964
2965       dynsym_xindex->set_after_input_sections();
2966
2967       // This tells the driver code to wait until the symbol table has
2968       // written out before writing out the postprocessing sections,
2969       // including the .dynsym_shndx section.
2970       this->any_postprocessing_sections_ = true;
2971     }
2972
2973   // Create the dynamic string table section.
2974
2975   Output_section* dynstr = this->choose_output_section(NULL, ".dynstr",
2976                                                        elfcpp::SHT_STRTAB,
2977                                                        elfcpp::SHF_ALLOC,
2978                                                        false, false, true,
2979                                                        false, false, false);
2980
2981   Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
2982   dynstr->add_output_section_data(strdata);
2983
2984   dynsym->set_link_section(dynstr);
2985   this->dynamic_section_->set_link_section(dynstr);
2986
2987   odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
2988   odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
2989
2990   *pdynstr = dynstr;
2991
2992   // Create the hash tables.
2993
2994   if (strcmp(parameters->options().hash_style(), "sysv") == 0
2995       || strcmp(parameters->options().hash_style(), "both") == 0)
2996     {
2997       unsigned char* phash;
2998       unsigned int hashlen;
2999       Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount,
3000                                     &phash, &hashlen);
3001
3002       Output_section* hashsec = this->choose_output_section(NULL, ".hash",
3003                                                             elfcpp::SHT_HASH,
3004                                                             elfcpp::SHF_ALLOC,
3005                                                             false, false, true,
3006                                                             false, false,
3007                                                             false);
3008
3009       Output_section_data* hashdata = new Output_data_const_buffer(phash,
3010                                                                    hashlen,
3011                                                                    align,
3012                                                                    "** hash");
3013       hashsec->add_output_section_data(hashdata);
3014
3015       hashsec->set_link_section(dynsym);
3016       hashsec->set_entsize(4);
3017
3018       odyn->add_section_address(elfcpp::DT_HASH, hashsec);
3019     }
3020
3021   if (strcmp(parameters->options().hash_style(), "gnu") == 0
3022       || strcmp(parameters->options().hash_style(), "both") == 0)
3023     {
3024       unsigned char* phash;
3025       unsigned int hashlen;
3026       Dynobj::create_gnu_hash_table(*pdynamic_symbols, local_symcount,
3027                                     &phash, &hashlen);
3028
3029       Output_section* hashsec = this->choose_output_section(NULL, ".gnu.hash",
3030                                                             elfcpp::SHT_GNU_HASH,
3031                                                             elfcpp::SHF_ALLOC,
3032                                                             false, false, true,
3033                                                             false, false,
3034                                                             false);
3035
3036       Output_section_data* hashdata = new Output_data_const_buffer(phash,
3037                                                                    hashlen,
3038                                                                    align,
3039                                                                    "** hash");
3040       hashsec->add_output_section_data(hashdata);
3041
3042       hashsec->set_link_section(dynsym);
3043
3044       // For a 64-bit target, the entries in .gnu.hash do not have a
3045       // uniform size, so we only set the entry size for a 32-bit
3046       // target.
3047       if (parameters->target().get_size() == 32)
3048         hashsec->set_entsize(4);
3049
3050       odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec);
3051     }
3052 }
3053
3054 // Assign offsets to each local portion of the dynamic symbol table.
3055
3056 void
3057 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects)
3058 {
3059   Output_section* dynsym = this->dynsym_section_;
3060   gold_assert(dynsym != NULL);
3061
3062   off_t off = dynsym->offset();
3063
3064   // Skip the dummy symbol at the start of the section.
3065   off += dynsym->entsize();
3066
3067   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
3068        p != input_objects->relobj_end();
3069        ++p)
3070     {
3071       unsigned int count = (*p)->set_local_dynsym_offset(off);
3072       off += count * dynsym->entsize();
3073     }
3074 }
3075
3076 // Create the version sections.
3077
3078 void
3079 Layout::create_version_sections(const Versions* versions,
3080                                 const Symbol_table* symtab,
3081                                 unsigned int local_symcount,
3082                                 const std::vector<Symbol*>& dynamic_symbols,
3083                                 const Output_section* dynstr)
3084 {
3085   if (!versions->any_defs() && !versions->any_needs())
3086     return;
3087
3088   switch (parameters->size_and_endianness())
3089     {
3090 #ifdef HAVE_TARGET_32_LITTLE
3091     case Parameters::TARGET_32_LITTLE:
3092       this->sized_create_version_sections<32, false>(versions, symtab,
3093                                                      local_symcount,
3094                                                      dynamic_symbols, dynstr);
3095       break;
3096 #endif
3097 #ifdef HAVE_TARGET_32_BIG
3098     case Parameters::TARGET_32_BIG:
3099       this->sized_create_version_sections<32, true>(versions, symtab,
3100                                                     local_symcount,
3101                                                     dynamic_symbols, dynstr);
3102       break;
3103 #endif
3104 #ifdef HAVE_TARGET_64_LITTLE
3105     case Parameters::TARGET_64_LITTLE:
3106       this->sized_create_version_sections<64, false>(versions, symtab,
3107                                                      local_symcount,
3108                                                      dynamic_symbols, dynstr);
3109       break;
3110 #endif
3111 #ifdef HAVE_TARGET_64_BIG
3112     case Parameters::TARGET_64_BIG:
3113       this->sized_create_version_sections<64, true>(versions, symtab,
3114                                                     local_symcount,
3115                                                     dynamic_symbols, dynstr);
3116       break;
3117 #endif
3118     default:
3119       gold_unreachable();
3120     }
3121 }
3122
3123 // Create the version sections, sized version.
3124
3125 template<int size, bool big_endian>
3126 void
3127 Layout::sized_create_version_sections(
3128     const Versions* versions,
3129     const Symbol_table* symtab,
3130     unsigned int local_symcount,
3131     const std::vector<Symbol*>& dynamic_symbols,
3132     const Output_section* dynstr)
3133 {
3134   Output_section* vsec = this->choose_output_section(NULL, ".gnu.version",
3135                                                      elfcpp::SHT_GNU_versym,
3136                                                      elfcpp::SHF_ALLOC,
3137                                                      false, false, true,
3138                                                      false, false, false);
3139
3140   unsigned char* vbuf;
3141   unsigned int vsize;
3142   versions->symbol_section_contents<size, big_endian>(symtab, &this->dynpool_,
3143                                                       local_symcount,
3144                                                       dynamic_symbols,
3145                                                       &vbuf, &vsize);
3146
3147   Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2,
3148                                                             "** versions");
3149
3150   vsec->add_output_section_data(vdata);
3151   vsec->set_entsize(2);
3152   vsec->set_link_section(this->dynsym_section_);
3153
3154   Output_data_dynamic* const odyn = this->dynamic_data_;
3155   odyn->add_section_address(elfcpp::DT_VERSYM, vsec);
3156
3157   if (versions->any_defs())
3158     {
3159       Output_section* vdsec;
3160       vdsec= this->choose_output_section(NULL, ".gnu.version_d",
3161                                          elfcpp::SHT_GNU_verdef,
3162                                          elfcpp::SHF_ALLOC,
3163                                          false, false, true, false, false,
3164                                          false);
3165
3166       unsigned char* vdbuf;
3167       unsigned int vdsize;
3168       unsigned int vdentries;
3169       versions->def_section_contents<size, big_endian>(&this->dynpool_, &vdbuf,
3170                                                        &vdsize, &vdentries);
3171
3172       Output_section_data* vddata =
3173         new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs");
3174
3175       vdsec->add_output_section_data(vddata);
3176       vdsec->set_link_section(dynstr);
3177       vdsec->set_info(vdentries);
3178
3179       odyn->add_section_address(elfcpp::DT_VERDEF, vdsec);
3180       odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries);
3181     }
3182
3183   if (versions->any_needs())
3184     {
3185       Output_section* vnsec;
3186       vnsec = this->choose_output_section(NULL, ".gnu.version_r",
3187                                           elfcpp::SHT_GNU_verneed,
3188                                           elfcpp::SHF_ALLOC,
3189                                           false, false, true, false, false,
3190                                           false);
3191
3192       unsigned char* vnbuf;
3193       unsigned int vnsize;
3194       unsigned int vnentries;
3195       versions->need_section_contents<size, big_endian>(&this->dynpool_,
3196                                                         &vnbuf, &vnsize,
3197                                                         &vnentries);
3198
3199       Output_section_data* vndata =
3200         new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs");
3201
3202       vnsec->add_output_section_data(vndata);
3203       vnsec->set_link_section(dynstr);
3204       vnsec->set_info(vnentries);
3205
3206       odyn->add_section_address(elfcpp::DT_VERNEED, vnsec);
3207       odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries);
3208     }
3209 }
3210
3211 // Create the .interp section and PT_INTERP segment.
3212
3213 void
3214 Layout::create_interp(const Target* target)
3215 {
3216   const char* interp = parameters->options().dynamic_linker();
3217   if (interp == NULL)
3218     {
3219       interp = target->dynamic_linker();
3220       gold_assert(interp != NULL);
3221     }
3222
3223   size_t len = strlen(interp) + 1;
3224
3225   Output_section_data* odata = new Output_data_const(interp, len, 1);
3226
3227   Output_section* osec = this->choose_output_section(NULL, ".interp",
3228                                                      elfcpp::SHT_PROGBITS,
3229                                                      elfcpp::SHF_ALLOC,
3230                                                      false, true, true,
3231                                                      false, false, false);
3232   osec->add_output_section_data(odata);
3233
3234   if (!this->script_options_->saw_phdrs_clause())
3235     {
3236       Output_segment* oseg = this->make_output_segment(elfcpp::PT_INTERP,
3237                                                        elfcpp::PF_R);
3238       oseg->add_output_section(osec, elfcpp::PF_R, false);
3239     }
3240 }
3241
3242 // Add dynamic tags for the PLT and the dynamic relocs.  This is
3243 // called by the target-specific code.  This does nothing if not doing
3244 // a dynamic link.
3245
3246 // USE_REL is true for REL relocs rather than RELA relocs.
3247
3248 // If PLT_GOT is not NULL, then DT_PLTGOT points to it.
3249
3250 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL,
3251 // and we also set DT_PLTREL.  We use PLT_REL's output section, since
3252 // some targets have multiple reloc sections in PLT_REL.
3253
3254 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA,
3255 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT.
3256
3257 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an
3258 // executable.
3259
3260 void
3261 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got,
3262                                 const Output_data* plt_rel,
3263                                 const Output_data_reloc_generic* dyn_rel,
3264                                 bool add_debug, bool dynrel_includes_plt)
3265 {
3266   Output_data_dynamic* odyn = this->dynamic_data_;
3267   if (odyn == NULL)
3268     return;
3269
3270   if (plt_got != NULL && plt_got->output_section() != NULL)
3271     odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got);
3272
3273   if (plt_rel != NULL && plt_rel->output_section() != NULL)
3274     {
3275       odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section());
3276       odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section());
3277       odyn->add_constant(elfcpp::DT_PLTREL,
3278                          use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA);
3279     }
3280
3281   if (dyn_rel != NULL && dyn_rel->output_section() != NULL)
3282     {
3283       odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA,
3284                                 dyn_rel);
3285       if (plt_rel != NULL && dynrel_includes_plt)
3286         odyn->add_section_size(use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ,
3287                                dyn_rel, plt_rel);
3288       else
3289         odyn->add_section_size(use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ,
3290                                dyn_rel);
3291       const int size = parameters->target().get_size();
3292       elfcpp::DT rel_tag;
3293       int rel_size;
3294       if (use_rel)
3295         {
3296           rel_tag = elfcpp::DT_RELENT;
3297           if (size == 32)
3298             rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size;
3299           else if (size == 64)
3300             rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size;
3301           else
3302             gold_unreachable();
3303         }
3304       else
3305         {
3306           rel_tag = elfcpp::DT_RELAENT;
3307           if (size == 32)
3308             rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size;
3309           else if (size == 64)
3310             rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size;
3311           else
3312             gold_unreachable();
3313         }
3314       odyn->add_constant(rel_tag, rel_size);
3315
3316       if (parameters->options().combreloc())
3317         {
3318           size_t c = dyn_rel->relative_reloc_count();
3319           if (c > 0)
3320             odyn->add_constant((use_rel
3321                                 ? elfcpp::DT_RELCOUNT
3322                                 : elfcpp::DT_RELACOUNT),
3323                                c);
3324         }
3325     }
3326
3327   if (add_debug && !parameters->options().shared())
3328     {
3329       // The value of the DT_DEBUG tag is filled in by the dynamic
3330       // linker at run time, and used by the debugger.
3331       odyn->add_constant(elfcpp::DT_DEBUG, 0);
3332     }
3333 }
3334
3335 // Finish the .dynamic section and PT_DYNAMIC segment.
3336
3337 void
3338 Layout::finish_dynamic_section(const Input_objects* input_objects,
3339                                const Symbol_table* symtab)
3340 {
3341   if (!this->script_options_->saw_phdrs_clause())
3342     {
3343       Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC,
3344                                                        (elfcpp::PF_R
3345                                                         | elfcpp::PF_W));
3346       oseg->add_output_section(this->dynamic_section_,
3347                                elfcpp::PF_R | elfcpp::PF_W,
3348                                false);
3349     }
3350
3351   Output_data_dynamic* const odyn = this->dynamic_data_;
3352
3353   for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
3354        p != input_objects->dynobj_end();
3355        ++p)
3356     {
3357       if (!(*p)->is_needed()
3358           && (*p)->input_file()->options().as_needed())
3359         {
3360           // This dynamic object was linked with --as-needed, but it
3361           // is not needed.
3362           continue;
3363         }
3364
3365       odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname());
3366     }
3367
3368   if (parameters->options().shared())
3369     {
3370       const char* soname = parameters->options().soname();
3371       if (soname != NULL)
3372         odyn->add_string(elfcpp::DT_SONAME, soname);
3373     }
3374
3375   Symbol* sym = symtab->lookup(parameters->options().init());
3376   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
3377     odyn->add_symbol(elfcpp::DT_INIT, sym);
3378
3379   sym = symtab->lookup(parameters->options().fini());
3380   if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
3381     odyn->add_symbol(elfcpp::DT_FINI, sym);
3382
3383   // Look for .init_array, .preinit_array and .fini_array by checking
3384   // section types.
3385   for(Layout::Section_list::const_iterator p = this->section_list_.begin();
3386       p != this->section_list_.end();
3387       ++p)
3388     switch((*p)->type())
3389       {
3390       case elfcpp::SHT_FINI_ARRAY:
3391         odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p);
3392         odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p);
3393         break;
3394       case elfcpp::SHT_INIT_ARRAY:
3395         odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p);
3396         odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p);
3397         break;
3398       case elfcpp::SHT_PREINIT_ARRAY:
3399         odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p);
3400         odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p);
3401         break;
3402       default:
3403         break;
3404       }
3405
3406   // Add a DT_RPATH entry if needed.
3407   const General_options::Dir_list& rpath(parameters->options().rpath());
3408   if (!rpath.empty())
3409     {
3410       std::string rpath_val;
3411       for (General_options::Dir_list::const_iterator p = rpath.begin();
3412            p != rpath.end();
3413            ++p)
3414         {
3415           if (rpath_val.empty())
3416             rpath_val = p->name();
3417           else
3418             {
3419               // Eliminate duplicates.
3420               General_options::Dir_list::const_iterator q;
3421               for (q = rpath.begin(); q != p; ++q)
3422                 if (q->name() == p->name())
3423                   break;
3424               if (q == p)
3425                 {
3426                   rpath_val += ':';
3427                   rpath_val += p->name();
3428                 }
3429             }
3430         }
3431
3432       odyn->add_string(elfcpp::DT_RPATH, rpath_val);
3433       if (parameters->options().enable_new_dtags())
3434         odyn->add_string(elfcpp::DT_RUNPATH, rpath_val);
3435     }
3436
3437   // Look for text segments that have dynamic relocations.
3438   bool have_textrel = false;
3439   if (!this->script_options_->saw_sections_clause())
3440     {
3441       for (Segment_list::const_iterator p = this->segment_list_.begin();
3442            p != this->segment_list_.end();
3443            ++p)
3444         {
3445           if (((*p)->flags() & elfcpp::PF_W) == 0
3446               && (*p)->dynamic_reloc_count() > 0)
3447             {
3448               have_textrel = true;
3449               break;
3450             }
3451         }
3452     }
3453   else
3454     {
3455       // We don't know the section -> segment mapping, so we are
3456       // conservative and just look for readonly sections with
3457       // relocations.  If those sections wind up in writable segments,
3458       // then we have created an unnecessary DT_TEXTREL entry.
3459       for (Section_list::const_iterator p = this->section_list_.begin();
3460            p != this->section_list_.end();
3461            ++p)
3462         {
3463           if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0
3464               && ((*p)->flags() & elfcpp::SHF_WRITE) == 0
3465               && ((*p)->dynamic_reloc_count() > 0))
3466             {
3467               have_textrel = true;
3468               break;
3469             }
3470         }
3471     }
3472
3473   // Add a DT_FLAGS entry. We add it even if no flags are set so that
3474   // post-link tools can easily modify these flags if desired.
3475   unsigned int flags = 0;
3476   if (have_textrel)
3477     {
3478       // Add a DT_TEXTREL for compatibility with older loaders.
3479       odyn->add_constant(elfcpp::DT_TEXTREL, 0);
3480       flags |= elfcpp::DF_TEXTREL;
3481
3482       if (parameters->options().text())
3483         gold_error(_("read-only segment has dynamic relocations"));
3484       else if (parameters->options().warn_shared_textrel()
3485                && parameters->options().shared())
3486         gold_warning(_("shared library text segment is not shareable"));
3487     }
3488   if (parameters->options().shared() && this->has_static_tls())
3489     flags |= elfcpp::DF_STATIC_TLS;
3490   if (parameters->options().origin())
3491     flags |= elfcpp::DF_ORIGIN;
3492   if (parameters->options().Bsymbolic())
3493     {
3494       flags |= elfcpp::DF_SYMBOLIC;
3495       // Add DT_SYMBOLIC for compatibility with older loaders.
3496       odyn->add_constant(elfcpp::DT_SYMBOLIC, 0);
3497     }
3498   if (parameters->options().now())
3499     flags |= elfcpp::DF_BIND_NOW;
3500   odyn->add_constant(elfcpp::DT_FLAGS, flags);
3501
3502   flags = 0;
3503   if (parameters->options().initfirst())
3504     flags |= elfcpp::DF_1_INITFIRST;
3505   if (parameters->options().interpose())
3506     flags |= elfcpp::DF_1_INTERPOSE;
3507   if (parameters->options().loadfltr())
3508     flags |= elfcpp::DF_1_LOADFLTR;
3509   if (parameters->options().nodefaultlib())
3510     flags |= elfcpp::DF_1_NODEFLIB;
3511   if (parameters->options().nodelete())
3512     flags |= elfcpp::DF_1_NODELETE;
3513   if (parameters->options().nodlopen())
3514     flags |= elfcpp::DF_1_NOOPEN;
3515   if (parameters->options().nodump())
3516     flags |= elfcpp::DF_1_NODUMP;
3517   if (!parameters->options().shared())
3518     flags &= ~(elfcpp::DF_1_INITFIRST
3519                | elfcpp::DF_1_NODELETE
3520                | elfcpp::DF_1_NOOPEN);
3521   if (parameters->options().origin())
3522     flags |= elfcpp::DF_1_ORIGIN;
3523   if (parameters->options().now())
3524     flags |= elfcpp::DF_1_NOW;
3525   if (flags)
3526     odyn->add_constant(elfcpp::DT_FLAGS_1, flags);
3527 }
3528
3529 // Set the size of the _DYNAMIC symbol table to be the size of the
3530 // dynamic data.
3531
3532 void
3533 Layout::set_dynamic_symbol_size(const Symbol_table* symtab)
3534 {
3535   Output_data_dynamic* const odyn = this->dynamic_data_;
3536   odyn->finalize_data_size();
3537   off_t data_size = odyn->data_size();
3538   const int size = parameters->target().get_size();
3539   if (size == 32)
3540     symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size);
3541   else if (size == 64)
3542     symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size);
3543   else
3544     gold_unreachable();
3545 }
3546
3547 // The mapping of input section name prefixes to output section names.
3548 // In some cases one prefix is itself a prefix of another prefix; in
3549 // such a case the longer prefix must come first.  These prefixes are
3550 // based on the GNU linker default ELF linker script.
3551
3552 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
3553 const Layout::Section_name_mapping Layout::section_name_mapping[] =
3554 {
3555   MAPPING_INIT(".text.", ".text"),
3556   MAPPING_INIT(".ctors.", ".ctors"),
3557   MAPPING_INIT(".dtors.", ".dtors"),
3558   MAPPING_INIT(".rodata.", ".rodata"),
3559   MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"),
3560   MAPPING_INIT(".data.rel.ro", ".data.rel.ro"),
3561   MAPPING_INIT(".data.", ".data"),
3562   MAPPING_INIT(".bss.", ".bss"),
3563   MAPPING_INIT(".tdata.", ".tdata"),
3564   MAPPING_INIT(".tbss.", ".tbss"),
3565   MAPPING_INIT(".init_array.", ".init_array"),
3566   MAPPING_INIT(".fini_array.", ".fini_array"),
3567   MAPPING_INIT(".sdata.", ".sdata"),
3568   MAPPING_INIT(".sbss.", ".sbss"),
3569   // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled
3570   // differently depending on whether it is creating a shared library.
3571   MAPPING_INIT(".sdata2.", ".sdata"),
3572   MAPPING_INIT(".sbss2.", ".sbss"),
3573   MAPPING_INIT(".lrodata.", ".lrodata"),
3574   MAPPING_INIT(".ldata.", ".ldata"),
3575   MAPPING_INIT(".lbss.", ".lbss"),
3576   MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"),
3577   MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"),
3578   MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"),
3579   MAPPING_INIT(".gnu.linkonce.t.", ".text"),
3580   MAPPING_INIT(".gnu.linkonce.r.", ".rodata"),
3581   MAPPING_INIT(".gnu.linkonce.d.", ".data"),
3582   MAPPING_INIT(".gnu.linkonce.b.", ".bss"),
3583   MAPPING_INIT(".gnu.linkonce.s.", ".sdata"),
3584   MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"),
3585   MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"),
3586   MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"),
3587   MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"),
3588   MAPPING_INIT(".gnu.linkonce.td.", ".tdata"),
3589   MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"),
3590   MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"),
3591   MAPPING_INIT(".gnu.linkonce.l.", ".ldata"),
3592   MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"),
3593   MAPPING_INIT(".ARM.extab", ".ARM.extab"),
3594   MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"),
3595   MAPPING_INIT(".ARM.exidx", ".ARM.exidx"),
3596   MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"),
3597 };
3598 #undef MAPPING_INIT
3599
3600 const int Layout::section_name_mapping_count =
3601   (sizeof(Layout::section_name_mapping)
3602    / sizeof(Layout::section_name_mapping[0]));
3603
3604 // Choose the output section name to use given an input section name.
3605 // Set *PLEN to the length of the name.  *PLEN is initialized to the
3606 // length of NAME.
3607
3608 const char*
3609 Layout::output_section_name(const char* name, size_t* plen)
3610 {
3611   // gcc 4.3 generates the following sorts of section names when it
3612   // needs a section name specific to a function:
3613   //   .text.FN
3614   //   .rodata.FN
3615   //   .sdata2.FN
3616   //   .data.FN
3617   //   .data.rel.FN
3618   //   .data.rel.local.FN
3619   //   .data.rel.ro.FN
3620   //   .data.rel.ro.local.FN
3621   //   .sdata.FN
3622   //   .bss.FN
3623   //   .sbss.FN
3624   //   .tdata.FN
3625   //   .tbss.FN
3626
3627   // The GNU linker maps all of those to the part before the .FN,
3628   // except that .data.rel.local.FN is mapped to .data, and
3629   // .data.rel.ro.local.FN is mapped to .data.rel.ro.  The sections
3630   // beginning with .data.rel.ro.local are grouped together.
3631
3632   // For an anonymous namespace, the string FN can contain a '.'.
3633
3634   // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the
3635   // GNU linker maps to .rodata.
3636
3637   // The .data.rel.ro sections are used with -z relro.  The sections
3638   // are recognized by name.  We use the same names that the GNU
3639   // linker does for these sections.
3640
3641   // It is hard to handle this in a principled way, so we don't even
3642   // try.  We use a table of mappings.  If the input section name is
3643   // not found in the table, we simply use it as the output section
3644   // name.
3645
3646   const Section_name_mapping* psnm = section_name_mapping;
3647   for (int i = 0; i < section_name_mapping_count; ++i, ++psnm)
3648     {
3649       if (strncmp(name, psnm->from, psnm->fromlen) == 0)
3650         {
3651           *plen = psnm->tolen;
3652           return psnm->to;
3653         }
3654     }
3655
3656   return name;
3657 }
3658
3659 // Check if a comdat group or .gnu.linkonce section with the given
3660 // NAME is selected for the link.  If there is already a section,
3661 // *KEPT_SECTION is set to point to the existing section and the
3662 // function returns false.  Otherwise, OBJECT, SHNDX, IS_COMDAT, and
3663 // IS_GROUP_NAME are recorded for this NAME in the layout object,
3664 // *KEPT_SECTION is set to the internal copy and the function returns
3665 // true.
3666
3667 bool
3668 Layout::find_or_add_kept_section(const std::string& name,
3669                                  Relobj* object,
3670                                  unsigned int shndx,
3671                                  bool is_comdat,
3672                                  bool is_group_name,
3673                                  Kept_section** kept_section)
3674 {
3675   // It's normal to see a couple of entries here, for the x86 thunk
3676   // sections.  If we see more than a few, we're linking a C++
3677   // program, and we resize to get more space to minimize rehashing.
3678   if (this->signatures_.size() > 4
3679       && !this->resized_signatures_)
3680     {
3681       reserve_unordered_map(&this->signatures_,
3682                             this->number_of_input_files_ * 64);
3683       this->resized_signatures_ = true;
3684     }
3685
3686   Kept_section candidate;
3687   std::pair<Signatures::iterator, bool> ins =
3688     this->signatures_.insert(std::make_pair(name, candidate));
3689
3690   if (kept_section != NULL)
3691     *kept_section = &ins.first->second;
3692   if (ins.second)
3693     {
3694       // This is the first time we've seen this signature.
3695       ins.first->second.set_object(object);
3696       ins.first->second.set_shndx(shndx);
3697       if (is_comdat)
3698         ins.first->second.set_is_comdat();
3699       if (is_group_name)
3700         ins.first->second.set_is_group_name();
3701       return true;
3702     }
3703
3704   // We have already seen this signature.
3705
3706   if (ins.first->second.is_group_name())
3707     {
3708       // We've already seen a real section group with this signature.
3709       // If the kept group is from a plugin object, and we're in the
3710       // replacement phase, accept the new one as a replacement.
3711       if (ins.first->second.object() == NULL
3712           && parameters->options().plugins()->in_replacement_phase())
3713         {
3714           ins.first->second.set_object(object);
3715           ins.first->second.set_shndx(shndx);
3716           return true;
3717         }
3718       return false;
3719     }
3720   else if (is_group_name)
3721     {
3722       // This is a real section group, and we've already seen a
3723       // linkonce section with this signature.  Record that we've seen
3724       // a section group, and don't include this section group.
3725       ins.first->second.set_is_group_name();
3726       return false;
3727     }
3728   else
3729     {
3730       // We've already seen a linkonce section and this is a linkonce
3731       // section.  These don't block each other--this may be the same
3732       // symbol name with different section types.
3733       return true;
3734     }
3735 }
3736
3737 // Store the allocated sections into the section list.
3738
3739 void
3740 Layout::get_allocated_sections(Section_list* section_list) const
3741 {
3742   for (Section_list::const_iterator p = this->section_list_.begin();
3743        p != this->section_list_.end();
3744        ++p)
3745     if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0)
3746       section_list->push_back(*p);
3747 }
3748
3749 // Create an output segment.
3750
3751 Output_segment*
3752 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
3753 {
3754   gold_assert(!parameters->options().relocatable());
3755   Output_segment* oseg = new Output_segment(type, flags);
3756   this->segment_list_.push_back(oseg);
3757
3758   if (type == elfcpp::PT_TLS)
3759     this->tls_segment_ = oseg;
3760   else if (type == elfcpp::PT_GNU_RELRO)
3761     this->relro_segment_ = oseg;
3762
3763   return oseg;
3764 }
3765
3766 // Write out the Output_sections.  Most won't have anything to write,
3767 // since most of the data will come from input sections which are
3768 // handled elsewhere.  But some Output_sections do have Output_data.
3769
3770 void
3771 Layout::write_output_sections(Output_file* of) const
3772 {
3773   for (Section_list::const_iterator p = this->section_list_.begin();
3774        p != this->section_list_.end();
3775        ++p)
3776     {
3777       if (!(*p)->after_input_sections())
3778         (*p)->write(of);
3779     }
3780 }
3781
3782 // Write out data not associated with a section or the symbol table.
3783
3784 void
3785 Layout::write_data(const Symbol_table* symtab, Output_file* of) const
3786 {
3787   if (!parameters->options().strip_all())
3788     {
3789       const Output_section* symtab_section = this->symtab_section_;
3790       for (Section_list::const_iterator p = this->section_list_.begin();
3791            p != this->section_list_.end();
3792            ++p)
3793         {
3794           if ((*p)->needs_symtab_index())
3795             {
3796               gold_assert(symtab_section != NULL);
3797               unsigned int index = (*p)->symtab_index();
3798               gold_assert(index > 0 && index != -1U);
3799               off_t off = (symtab_section->offset()
3800                            + index * symtab_section->entsize());
3801               symtab->write_section_symbol(*p, this->symtab_xindex_, of, off);
3802             }
3803         }
3804     }
3805
3806   const Output_section* dynsym_section = this->dynsym_section_;
3807   for (Section_list::const_iterator p = this->section_list_.begin();
3808        p != this->section_list_.end();
3809        ++p)
3810     {
3811       if ((*p)->needs_dynsym_index())
3812         {
3813           gold_assert(dynsym_section != NULL);
3814           unsigned int index = (*p)->dynsym_index();
3815           gold_assert(index > 0 && index != -1U);
3816           off_t off = (dynsym_section->offset()
3817                        + index * dynsym_section->entsize());
3818           symtab->write_section_symbol(*p, this->dynsym_xindex_, of, off);
3819         }
3820     }
3821
3822   // Write out the Output_data which are not in an Output_section.
3823   for (Data_list::const_iterator p = this->special_output_list_.begin();
3824        p != this->special_output_list_.end();
3825        ++p)
3826     (*p)->write(of);
3827 }
3828
3829 // Write out the Output_sections which can only be written after the
3830 // input sections are complete.
3831
3832 void
3833 Layout::write_sections_after_input_sections(Output_file* of)
3834 {
3835   // Determine the final section offsets, and thus the final output
3836   // file size.  Note we finalize the .shstrab last, to allow the
3837   // after_input_section sections to modify their section-names before
3838   // writing.
3839   if (this->any_postprocessing_sections_)
3840     {
3841       off_t off = this->output_file_size_;
3842       off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS);
3843
3844       // Now that we've finalized the names, we can finalize the shstrab.
3845       off =
3846         this->set_section_offsets(off,
3847                                   STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS);
3848
3849       if (off > this->output_file_size_)
3850         {
3851           of->resize(off);
3852           this->output_file_size_ = off;
3853         }
3854     }
3855
3856   for (Section_list::const_iterator p = this->section_list_.begin();
3857        p != this->section_list_.end();
3858        ++p)
3859     {
3860       if ((*p)->after_input_sections())
3861         (*p)->write(of);
3862     }
3863
3864   this->section_headers_->write(of);
3865 }
3866
3867 // If the build ID requires computing a checksum, do so here, and
3868 // write it out.  We compute a checksum over the entire file because
3869 // that is simplest.
3870
3871 void
3872 Layout::write_build_id(Output_file* of) const
3873 {
3874   if (this->build_id_note_ == NULL)
3875     return;
3876
3877   const unsigned char* iv = of->get_input_view(0, this->output_file_size_);
3878
3879   unsigned char* ov = of->get_output_view(this->build_id_note_->offset(),
3880                                           this->build_id_note_->data_size());
3881
3882   const char* style = parameters->options().build_id();
3883   if (strcmp(style, "sha1") == 0)
3884     {
3885       sha1_ctx ctx;
3886       sha1_init_ctx(&ctx);
3887       sha1_process_bytes(iv, this->output_file_size_, &ctx);
3888       sha1_finish_ctx(&ctx, ov);
3889     }
3890   else if (strcmp(style, "md5") == 0)
3891     {
3892       md5_ctx ctx;
3893       md5_init_ctx(&ctx);
3894       md5_process_bytes(iv, this->output_file_size_, &ctx);
3895       md5_finish_ctx(&ctx, ov);
3896     }
3897   else
3898     gold_unreachable();
3899
3900   of->write_output_view(this->build_id_note_->offset(),
3901                         this->build_id_note_->data_size(),
3902                         ov);
3903
3904   of->free_input_view(0, this->output_file_size_, iv);
3905 }
3906
3907 // Write out a binary file.  This is called after the link is
3908 // complete.  IN is the temporary output file we used to generate the
3909 // ELF code.  We simply walk through the segments, read them from
3910 // their file offset in IN, and write them to their load address in
3911 // the output file.  FIXME: with a bit more work, we could support
3912 // S-records and/or Intel hex format here.
3913
3914 void
3915 Layout::write_binary(Output_file* in) const
3916 {
3917   gold_assert(parameters->options().oformat_enum()
3918               == General_options::OBJECT_FORMAT_BINARY);
3919
3920   // Get the size of the binary file.
3921   uint64_t max_load_address = 0;
3922   for (Segment_list::const_iterator p = this->segment_list_.begin();
3923        p != this->segment_list_.end();
3924        ++p)
3925     {
3926       if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
3927         {
3928           uint64_t max_paddr = (*p)->paddr() + (*p)->filesz();
3929           if (max_paddr > max_load_address)
3930             max_load_address = max_paddr;
3931         }
3932     }
3933
3934   Output_file out(parameters->options().output_file_name());
3935   out.open(max_load_address);
3936
3937   for (Segment_list::const_iterator p = this->segment_list_.begin();
3938        p != this->segment_list_.end();
3939        ++p)
3940     {
3941       if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0)
3942         {
3943           const unsigned char* vin = in->get_input_view((*p)->offset(),
3944                                                         (*p)->filesz());
3945           unsigned char* vout = out.get_output_view((*p)->paddr(),
3946                                                     (*p)->filesz());
3947           memcpy(vout, vin, (*p)->filesz());
3948           out.write_output_view((*p)->paddr(), (*p)->filesz(), vout);
3949           in->free_input_view((*p)->offset(), (*p)->filesz(), vin);
3950         }
3951     }
3952
3953   out.close();
3954 }
3955
3956 // Print the output sections to the map file.
3957
3958 void
3959 Layout::print_to_mapfile(Mapfile* mapfile) const
3960 {
3961   for (Segment_list::const_iterator p = this->segment_list_.begin();
3962        p != this->segment_list_.end();
3963        ++p)
3964     (*p)->print_sections_to_mapfile(mapfile);
3965 }
3966
3967 // Print statistical information to stderr.  This is used for --stats.
3968
3969 void
3970 Layout::print_stats() const
3971 {
3972   this->namepool_.print_stats("section name pool");
3973   this->sympool_.print_stats("output symbol name pool");
3974   this->dynpool_.print_stats("dynamic name pool");
3975
3976   for (Section_list::const_iterator p = this->section_list_.begin();
3977        p != this->section_list_.end();
3978        ++p)
3979     (*p)->print_merge_stats();
3980 }
3981
3982 // Write_sections_task methods.
3983
3984 // We can always run this task.
3985
3986 Task_token*
3987 Write_sections_task::is_runnable()
3988 {
3989   return NULL;
3990 }
3991
3992 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER
3993 // when finished.
3994
3995 void
3996 Write_sections_task::locks(Task_locker* tl)
3997 {
3998   tl->add(this, this->output_sections_blocker_);
3999   tl->add(this, this->final_blocker_);
4000 }
4001
4002 // Run the task--write out the data.
4003
4004 void
4005 Write_sections_task::run(Workqueue*)
4006 {
4007   this->layout_->write_output_sections(this->of_);
4008 }
4009
4010 // Write_data_task methods.
4011
4012 // We can always run this task.
4013
4014 Task_token*
4015 Write_data_task::is_runnable()
4016 {
4017   return NULL;
4018 }
4019
4020 // We need to unlock FINAL_BLOCKER when finished.
4021
4022 void
4023 Write_data_task::locks(Task_locker* tl)
4024 {
4025   tl->add(this, this->final_blocker_);
4026 }
4027
4028 // Run the task--write out the data.
4029
4030 void
4031 Write_data_task::run(Workqueue*)
4032 {
4033   this->layout_->write_data(this->symtab_, this->of_);
4034 }
4035
4036 // Write_symbols_task methods.
4037
4038 // We can always run this task.
4039
4040 Task_token*
4041 Write_symbols_task::is_runnable()
4042 {
4043   return NULL;
4044 }
4045
4046 // We need to unlock FINAL_BLOCKER when finished.
4047
4048 void
4049 Write_symbols_task::locks(Task_locker* tl)
4050 {
4051   tl->add(this, this->final_blocker_);
4052 }
4053
4054 // Run the task--write out the symbols.
4055
4056 void
4057 Write_symbols_task::run(Workqueue*)
4058 {
4059   this->symtab_->write_globals(this->sympool_, this->dynpool_,
4060                                this->layout_->symtab_xindex(),
4061                                this->layout_->dynsym_xindex(), this->of_);
4062 }
4063
4064 // Write_after_input_sections_task methods.
4065
4066 // We can only run this task after the input sections have completed.
4067
4068 Task_token*
4069 Write_after_input_sections_task::is_runnable()
4070 {
4071   if (this->input_sections_blocker_->is_blocked())
4072     return this->input_sections_blocker_;
4073   return NULL;
4074 }
4075
4076 // We need to unlock FINAL_BLOCKER when finished.
4077
4078 void
4079 Write_after_input_sections_task::locks(Task_locker* tl)
4080 {
4081   tl->add(this, this->final_blocker_);
4082 }
4083
4084 // Run the task.
4085
4086 void
4087 Write_after_input_sections_task::run(Workqueue*)
4088 {
4089   this->layout_->write_sections_after_input_sections(this->of_);
4090 }
4091
4092 // Close_task_runner methods.
4093
4094 // Run the task--close the file.
4095
4096 void
4097 Close_task_runner::run(Workqueue*, const Task*)
4098 {
4099   // If we need to compute a checksum for the BUILD if, we do so here.
4100   this->layout_->write_build_id(this->of_);
4101
4102   // If we've been asked to create a binary file, we do so here.
4103   if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF)
4104     this->layout_->write_binary(this->of_);
4105
4106   this->of_->close();
4107 }
4108
4109 // Instantiate the templates we need.  We could use the configure
4110 // script to restrict this to only the ones for implemented targets.
4111
4112 #ifdef HAVE_TARGET_32_LITTLE
4113 template
4114 Output_section*
4115 Layout::layout<32, false>(Sized_relobj<32, false>* object, unsigned int shndx,
4116                           const char* name,
4117                           const elfcpp::Shdr<32, false>& shdr,
4118                           unsigned int, unsigned int, off_t*);
4119 #endif
4120
4121 #ifdef HAVE_TARGET_32_BIG
4122 template
4123 Output_section*
4124 Layout::layout<32, true>(Sized_relobj<32, true>* object, unsigned int shndx,
4125                          const char* name,
4126                          const elfcpp::Shdr<32, true>& shdr,
4127                          unsigned int, unsigned int, off_t*);
4128 #endif
4129
4130 #ifdef HAVE_TARGET_64_LITTLE
4131 template
4132 Output_section*
4133 Layout::layout<64, false>(Sized_relobj<64, false>* object, unsigned int shndx,
4134                           const char* name,
4135                           const elfcpp::Shdr<64, false>& shdr,
4136                           unsigned int, unsigned int, off_t*);
4137 #endif
4138
4139 #ifdef HAVE_TARGET_64_BIG
4140 template
4141 Output_section*
4142 Layout::layout<64, true>(Sized_relobj<64, true>* object, unsigned int shndx,
4143                          const char* name,
4144                          const elfcpp::Shdr<64, true>& shdr,
4145                          unsigned int, unsigned int, off_t*);
4146 #endif
4147
4148 #ifdef HAVE_TARGET_32_LITTLE
4149 template
4150 Output_section*
4151 Layout::layout_reloc<32, false>(Sized_relobj<32, false>* object,
4152                                 unsigned int reloc_shndx,
4153                                 const elfcpp::Shdr<32, false>& shdr,
4154                                 Output_section* data_section,
4155                                 Relocatable_relocs* rr);
4156 #endif
4157
4158 #ifdef HAVE_TARGET_32_BIG
4159 template
4160 Output_section*
4161 Layout::layout_reloc<32, true>(Sized_relobj<32, true>* object,
4162                                unsigned int reloc_shndx,
4163                                const elfcpp::Shdr<32, true>& shdr,
4164                                Output_section* data_section,
4165                                Relocatable_relocs* rr);
4166 #endif
4167
4168 #ifdef HAVE_TARGET_64_LITTLE
4169 template
4170 Output_section*
4171 Layout::layout_reloc<64, false>(Sized_relobj<64, false>* object,
4172                                 unsigned int reloc_shndx,
4173                                 const elfcpp::Shdr<64, false>& shdr,
4174                                 Output_section* data_section,
4175                                 Relocatable_relocs* rr);
4176 #endif
4177
4178 #ifdef HAVE_TARGET_64_BIG
4179 template
4180 Output_section*
4181 Layout::layout_reloc<64, true>(Sized_relobj<64, true>* object,
4182                                unsigned int reloc_shndx,
4183                                const elfcpp::Shdr<64, true>& shdr,
4184                                Output_section* data_section,
4185                                Relocatable_relocs* rr);
4186 #endif
4187
4188 #ifdef HAVE_TARGET_32_LITTLE
4189 template
4190 void
4191 Layout::layout_group<32, false>(Symbol_table* symtab,
4192                                 Sized_relobj<32, false>* object,
4193                                 unsigned int,
4194                                 const char* group_section_name,
4195                                 const char* signature,
4196                                 const elfcpp::Shdr<32, false>& shdr,
4197                                 elfcpp::Elf_Word flags,
4198                                 std::vector<unsigned int>* shndxes);
4199 #endif
4200
4201 #ifdef HAVE_TARGET_32_BIG
4202 template
4203 void
4204 Layout::layout_group<32, true>(Symbol_table* symtab,
4205                                Sized_relobj<32, true>* object,
4206                                unsigned int,
4207                                const char* group_section_name,
4208                                const char* signature,
4209                                const elfcpp::Shdr<32, true>& shdr,
4210                                elfcpp::Elf_Word flags,
4211                                std::vector<unsigned int>* shndxes);
4212 #endif
4213
4214 #ifdef HAVE_TARGET_64_LITTLE
4215 template
4216 void
4217 Layout::layout_group<64, false>(Symbol_table* symtab,
4218                                 Sized_relobj<64, false>* object,
4219                                 unsigned int,
4220                                 const char* group_section_name,
4221                                 const char* signature,
4222                                 const elfcpp::Shdr<64, false>& shdr,
4223                                 elfcpp::Elf_Word flags,
4224                                 std::vector<unsigned int>* shndxes);
4225 #endif
4226
4227 #ifdef HAVE_TARGET_64_BIG
4228 template
4229 void
4230 Layout::layout_group<64, true>(Symbol_table* symtab,
4231                                Sized_relobj<64, true>* object,
4232                                unsigned int,
4233                                const char* group_section_name,
4234                                const char* signature,
4235                                const elfcpp::Shdr<64, true>& shdr,
4236                                elfcpp::Elf_Word flags,
4237                                std::vector<unsigned int>* shndxes);
4238 #endif
4239
4240 #ifdef HAVE_TARGET_32_LITTLE
4241 template
4242 Output_section*
4243 Layout::layout_eh_frame<32, false>(Sized_relobj<32, false>* object,
4244                                    const unsigned char* symbols,
4245                                    off_t symbols_size,
4246                                    const unsigned char* symbol_names,
4247                                    off_t symbol_names_size,
4248                                    unsigned int shndx,
4249                                    const elfcpp::Shdr<32, false>& shdr,
4250                                    unsigned int reloc_shndx,
4251                                    unsigned int reloc_type,
4252                                    off_t* off);
4253 #endif
4254
4255 #ifdef HAVE_TARGET_32_BIG
4256 template
4257 Output_section*
4258 Layout::layout_eh_frame<32, true>(Sized_relobj<32, true>* object,
4259                                    const unsigned char* symbols,
4260                                    off_t symbols_size,
4261                                   const unsigned char* symbol_names,
4262                                   off_t symbol_names_size,
4263                                   unsigned int shndx,
4264                                   const elfcpp::Shdr<32, true>& shdr,
4265                                   unsigned int reloc_shndx,
4266                                   unsigned int reloc_type,
4267                                   off_t* off);
4268 #endif
4269
4270 #ifdef HAVE_TARGET_64_LITTLE
4271 template
4272 Output_section*
4273 Layout::layout_eh_frame<64, false>(Sized_relobj<64, false>* object,
4274                                    const unsigned char* symbols,
4275                                    off_t symbols_size,
4276                                    const unsigned char* symbol_names,
4277                                    off_t symbol_names_size,
4278                                    unsigned int shndx,
4279                                    const elfcpp::Shdr<64, false>& shdr,
4280                                    unsigned int reloc_shndx,
4281                                    unsigned int reloc_type,
4282                                    off_t* off);
4283 #endif
4284
4285 #ifdef HAVE_TARGET_64_BIG
4286 template
4287 Output_section*
4288 Layout::layout_eh_frame<64, true>(Sized_relobj<64, true>* object,
4289                                    const unsigned char* symbols,
4290                                    off_t symbols_size,
4291                                   const unsigned char* symbol_names,
4292                                   off_t symbol_names_size,
4293                                   unsigned int shndx,
4294                                   const elfcpp::Shdr<64, true>& shdr,
4295                                   unsigned int reloc_shndx,
4296                                   unsigned int reloc_type,
4297                                   off_t* off);
4298 #endif
4299
4300 } // End namespace gold.