gold/x86_64.cc

   1 // x86_64.cc -- x86_64 target support for gold.
   2
   3 // Copyright 2006, 2007, 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
   9 // modify it under the terms of the GNU Library General Public License
  10 // as published by the Free Software Foundation; either version 2, or
  11 // (at your option) any later version.
  12
  13 // In addition to the permissions in the GNU Library General Public
  14 // License, the Free Software Foundation gives you unlimited
  15 // permission to link the compiled version of this file into
  16 // combinations with other programs, and to distribute those
  17 // combinations without any restriction coming from the use of this
  18 // file.  (The Library Public License restrictions do apply in other
  19 // respects; for example, they cover modification of the file, and
  20 /// distribution when not linked into a combined executable.)
  21
  22 // This program is distributed in the hope that it will be useful, but
  23 // WITHOUT ANY WARRANTY; without even the implied warranty of
  24 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  25 // Library General Public License for more details.
  26
  27 // You should have received a copy of the GNU Library General Public
  28 // License along with this program; if not, write to the Free Software
  29 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
  30 // 02110-1301, USA.
  31
  32 #include "gold.h"
  33
  34 #include <cstring>
  35
  36 #include "elfcpp.h"
  37 #include "parameters.h"
  38 #include "reloc.h"
  39 #include "x86_64.h"
  40 #include "object.h"
  41 #include "symtab.h"
  42 #include "layout.h"
  43 #include "output.h"
  44 #include "target.h"
  45 #include "target-reloc.h"
  46 #include "target-select.h"
  47 #include "tls.h"
  48
  49 namespace
  50 {
  51
  52 using namespace gold;
  53
  54 class Output_data_plt_x86_64;
  55
  56 // The x86_64 target class.
  57 // See the ABI at
  58 //   http://www.x86-64.org/documentation/abi.pdf
  59 // TLS info comes from
  60 //   http://people.redhat.com/drepper/tls.pdf
  61 //   http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
  62
  63 class Target_x86_64 : public Sized_target<64, false>
  64 {
  65  public:
  66   // In the x86_64 ABI (p 68), it says "The AMD64 ABI architectures
  67   // uses only Elf64_Rela relocation entries with explicit addends."
  68   typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
  69
  70   Target_x86_64()
  71     : Sized_target<64, false>(&x86_64_info),
  72       got_(NULL), plt_(NULL), got_plt_(NULL), rela_dyn_(NULL),
  73       copy_relocs_(NULL), dynbss_(NULL)
  74   { }
  75
  76   // Scan the relocations to look for symbol adjustments.
  77   void
  78   scan_relocs(const General_options& options,
  79               Symbol_table* symtab,
  80               Layout* layout,
  81               Sized_relobj<64, false>* object,
  82               unsigned int data_shndx,
  83               unsigned int sh_type,
  84               const unsigned char* prelocs,
  85               size_t reloc_count,
  86               Output_section* output_section,
  87               bool needs_special_offset_handling,
  88               size_t local_symbol_count,
  89               const unsigned char* plocal_symbols);
  90
  91   // Finalize the sections.
  92   void
  93   do_finalize_sections(Layout*);
  94
  95   // Return the value to use for a dynamic which requires special
  96   // treatment.
  97   uint64_t
  98   do_dynsym_value(const Symbol*) const;
  99
 100   // Relocate a section.
 101   void
 102   relocate_section(const Relocate_info<64, false>*,
 103                    unsigned int sh_type,
 104                    const unsigned char* prelocs,
 105                    size_t reloc_count,
 106                    Output_section* output_section,
 107                    bool needs_special_offset_handling,
 108                    unsigned char* view,
 109                    elfcpp::Elf_types<64>::Elf_Addr view_address,
 110                    off_t view_size);
 111
 112   // Return a string used to fill a code section with nops.
 113   std::string
 114   do_code_fill(off_t length);
 115
 116   // Return whether SYM is defined by the ABI.
 117   bool
 118   do_is_defined_by_abi(Symbol* sym) const
 119   { return strcmp(sym->name(), "__tls_get_addr") == 0; }
 120
 121   // Return the size of the GOT section.
 122   off_t
 123   got_size()
 124   {
 125     gold_assert(this->got_ != NULL);
 126     return this->got_->data_size();
 127   }
 128
 129  private:
 130   // The class which scans relocations.
 131   struct Scan
 132   {
 133     inline void
 134     local(const General_options& options, Symbol_table* symtab,
 135           Layout* layout, Target_x86_64* target,
 136           Sized_relobj<64, false>* object,
 137           unsigned int data_shndx,
 138           Output_section* output_section,
 139           const elfcpp::Rela<64, false>& reloc, unsigned int r_type,
 140           const elfcpp::Sym<64, false>& lsym);
 141
 142     inline void
 143     global(const General_options& options, Symbol_table* symtab,
 144            Layout* layout, Target_x86_64* target,
 145            Sized_relobj<64, false>* object,
 146            unsigned int data_shndx,
 147            Output_section* output_section,
 148            const elfcpp::Rela<64, false>& reloc, unsigned int r_type,
 149            Symbol* gsym);
 150
 151     static void
 152     unsupported_reloc_local(Sized_relobj<64, false>*, unsigned int r_type);
 153
 154     static void
 155     unsupported_reloc_global(Sized_relobj<64, false>*, unsigned int r_type,
 156                              Symbol*);
 157   };
 158
 159   // The class which implements relocation.
 160   class Relocate
 161   {
 162    public:
 163     Relocate()
 164       : skip_call_tls_get_addr_(false)
 165     { }
 166
 167     ~Relocate()
 168     {
 169       if (this->skip_call_tls_get_addr_)
 170         {
 171           // FIXME: This needs to specify the location somehow.
 172           gold_error(_("missing expected TLS relocation"));
 173         }
 174     }
 175
 176     // Do a relocation.  Return false if the caller should not issue
 177     // any warnings about this relocation.
 178     inline bool
 179     relocate(const Relocate_info<64, false>*, Target_x86_64*, size_t relnum,
 180              const elfcpp::Rela<64, false>&,
 181              unsigned int r_type, const Sized_symbol<64>*,
 182              const Symbol_value<64>*,
 183              unsigned char*, elfcpp::Elf_types<64>::Elf_Addr,
 184              off_t);
 185
 186    private:
 187     // Do a TLS relocation.
 188     inline void
 189     relocate_tls(const Relocate_info<64, false>*, size_t relnum,
 190                  const elfcpp::Rela<64, false>&,
 191                  unsigned int r_type, const Sized_symbol<64>*,
 192                  const Symbol_value<64>*,
 193                  unsigned char*, elfcpp::Elf_types<64>::Elf_Addr, off_t);
 194
 195     // Do a TLS General-Dynamic to Local-Exec transition.
 196     inline void
 197     tls_gd_to_le(const Relocate_info<64, false>*, size_t relnum,
 198                  Output_segment* tls_segment,
 199                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 200                  elfcpp::Elf_types<64>::Elf_Addr value,
 201                  unsigned char* view,
 202                  off_t view_size);
 203
 204     // Do a TLS Local-Dynamic to Local-Exec transition.
 205     inline void
 206     tls_ld_to_le(const Relocate_info<64, false>*, size_t relnum,
 207                  Output_segment* tls_segment,
 208                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 209                  elfcpp::Elf_types<64>::Elf_Addr value,
 210                  unsigned char* view,
 211                  off_t view_size);
 212
 213     // Do a TLS Initial-Exec to Local-Exec transition.
 214     static inline void
 215     tls_ie_to_le(const Relocate_info<64, false>*, size_t relnum,
 216                  Output_segment* tls_segment,
 217                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 218                  elfcpp::Elf_types<64>::Elf_Addr value,
 219                  unsigned char* view,
 220                  off_t view_size);
 221
 222     // This is set if we should skip the next reloc, which should be a
 223     // PLT32 reloc against ___tls_get_addr.
 224     bool skip_call_tls_get_addr_;
 225   };
 226
 227   // Adjust TLS relocation type based on the options and whether this
 228   // is a local symbol.
 229   static tls::Tls_optimization
 230   optimize_tls_reloc(bool is_final, int r_type);
 231
 232   // Get the GOT section, creating it if necessary.
 233   Output_data_got<64, false>*
 234   got_section(Symbol_table*, Layout*);
 235
 236   // Get the GOT PLT section.
 237   Output_data_space*
 238   got_plt_section() const
 239   {
 240     gold_assert(this->got_plt_ != NULL);
 241     return this->got_plt_;
 242   }
 243
 244   // Create a PLT entry for a global symbol.
 245   void
 246   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 247
 248   // Get the PLT section.
 249   Output_data_plt_x86_64*
 250   plt_section() const
 251   {
 252     gold_assert(this->plt_ != NULL);
 253     return this->plt_;
 254   }
 255
 256   // Get the dynamic reloc section, creating it if necessary.
 257   Reloc_section*
 258   rela_dyn_section(Layout*);
 259
 260   // Return true if the symbol may need a COPY relocation.
 261   // References from an executable object to non-function symbols
 262   // defined in a dynamic object may need a COPY relocation.
 263   bool
 264   may_need_copy_reloc(Symbol* gsym)
 265   {
 266     return (!parameters->output_is_shared()
 267             && gsym->is_from_dynobj()
 268             && gsym->type() != elfcpp::STT_FUNC);
 269   }
 270
 271   // Copy a relocation against a global symbol.
 272   void
 273   copy_reloc(const General_options*, Symbol_table*, Layout*,
 274              Sized_relobj<64, false>*, unsigned int,
 275              Symbol*, const elfcpp::Rela<64, false>&);
 276
 277   // Information about this specific target which we pass to the
 278   // general Target structure.
 279   static const Target::Target_info x86_64_info;
 280
 281   // The GOT section.
 282   Output_data_got<64, false>* got_;
 283   // The PLT section.
 284   Output_data_plt_x86_64* plt_;
 285   // The GOT PLT section.
 286   Output_data_space* got_plt_;
 287   // The dynamic reloc section.
 288   Reloc_section* rela_dyn_;
 289   // Relocs saved to avoid a COPY reloc.
 290   Copy_relocs<64, false>* copy_relocs_;
 291   // Space for variables copied with a COPY reloc.
 292   Output_data_space* dynbss_;
 293 };
 294
 295 const Target::Target_info Target_x86_64::x86_64_info =
 296 {
 297   64,                   // size
 298   false,                // is_big_endian
 299   elfcpp::EM_X86_64,    // machine_code
 300   false,                // has_make_symbol
 301   false,                // has_resolve
 302   true,                 // has_code_fill
 303   true,                 // is_default_stack_executable
 304   "/lib/ld64.so.1",     // program interpreter
 305   0x400000,             // default_text_segment_address
 306   0x1000,               // abi_pagesize
 307   0x1000                // common_pagesize
 308 };
 309
 310 // Get the GOT section, creating it if necessary.
 311
 312 Output_data_got<64, false>*
 313 Target_x86_64::got_section(Symbol_table* symtab, Layout* layout)
 314 {
 315   if (this->got_ == NULL)
 316     {
 317       gold_assert(symtab != NULL && layout != NULL);
 318
 319       this->got_ = new Output_data_got<64, false>();
 320
 321       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 322                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 323                                       this->got_);
 324
 325       // The old GNU linker creates a .got.plt section.  We just
 326       // create another set of data in the .got section.  Note that we
 327       // always create a PLT if we create a GOT, although the PLT
 328       // might be empty.
 329       this->got_plt_ = new Output_data_space(8);
 330       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 331                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 332                                       this->got_plt_);
 333
 334       // The first three entries are reserved.
 335       this->got_plt_->set_space_size(3 * 8);
 336
 337       // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
 338       symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
 339                                     this->got_plt_,
 340                                     0, 0, elfcpp::STT_OBJECT,
 341                                     elfcpp::STB_LOCAL,
 342                                     elfcpp::STV_HIDDEN, 0,
 343                                     false, false);
 344     }
 345
 346   return this->got_;
 347 }
 348
 349 // Get the dynamic reloc section, creating it if necessary.
 350
 351 Target_x86_64::Reloc_section*
 352 Target_x86_64::rela_dyn_section(Layout* layout)
 353 {
 354   if (this->rela_dyn_ == NULL)
 355     {
 356       gold_assert(layout != NULL);
 357       this->rela_dyn_ = new Reloc_section();
 358       layout->add_output_section_data(".rela.dyn", elfcpp::SHT_RELA,
 359                                       elfcpp::SHF_ALLOC, this->rela_dyn_);
 360     }
 361   return this->rela_dyn_;
 362 }
 363
 364 // A class to handle the PLT data.
 365
 366 class Output_data_plt_x86_64 : public Output_section_data
 367 {
 368  public:
 369   typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
 370
 371   Output_data_plt_x86_64(Layout*, Output_data_space*);
 372
 373   // Add an entry to the PLT.
 374   void
 375   add_entry(Symbol* gsym);
 376
 377   // Return the .rel.plt section data.
 378   const Reloc_section*
 379   rel_plt() const
 380   { return this->rel_; }
 381
 382  protected:
 383   void
 384   do_adjust_output_section(Output_section* os);
 385
 386  private:
 387   // The size of an entry in the PLT.
 388   static const int plt_entry_size = 16;
 389
 390   // The first entry in the PLT.
 391   // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same
 392   // procedure linkage table for both programs and shared objects."
 393   static unsigned char first_plt_entry[plt_entry_size];
 394
 395   // Other entries in the PLT for an executable.
 396   static unsigned char plt_entry[plt_entry_size];
 397
 398   // Set the final size.
 399   void
 400   do_set_address(uint64_t, off_t)
 401   { this->set_data_size((this->count_ + 1) * plt_entry_size); }
 402
 403   // Write out the PLT data.
 404   void
 405   do_write(Output_file*);
 406
 407   // The reloc section.
 408   Reloc_section* rel_;
 409   // The .got.plt section.
 410   Output_data_space* got_plt_;
 411   // The number of PLT entries.
 412   unsigned int count_;
 413 };
 414
 415 // Create the PLT section.  The ordinary .got section is an argument,
 416 // since we need to refer to the start.  We also create our own .got
 417 // section just for PLT entries.
 418
 419 Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout,
 420                                                Output_data_space* got_plt)
 421   : Output_section_data(8), got_plt_(got_plt), count_(0)
 422 {
 423   this->rel_ = new Reloc_section();
 424   layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
 425                                   elfcpp::SHF_ALLOC, this->rel_);
 426 }
 427
 428 void
 429 Output_data_plt_x86_64::do_adjust_output_section(Output_section* os)
 430 {
 431   // UnixWare sets the entsize of .plt to 4, and so does the old GNU
 432   // linker, and so do we.
 433   os->set_entsize(4);
 434 }
 435
 436 // Add an entry to the PLT.
 437
 438 void
 439 Output_data_plt_x86_64::add_entry(Symbol* gsym)
 440 {
 441   gold_assert(!gsym->has_plt_offset());
 442
 443   // Note that when setting the PLT offset we skip the initial
 444   // reserved PLT entry.
 445   gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
 446
 447   ++this->count_;
 448
 449   off_t got_offset = this->got_plt_->data_size();
 450
 451   // Every PLT entry needs a GOT entry which points back to the PLT
 452   // entry (this will be changed by the dynamic linker, normally
 453   // lazily when the function is called).
 454   this->got_plt_->set_space_size(got_offset + 8);
 455
 456   // Every PLT entry needs a reloc.
 457   gsym->set_needs_dynsym_entry();
 458   this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_,
 459                          got_offset, 0);
 460
 461   // Note that we don't need to save the symbol.  The contents of the
 462   // PLT are independent of which symbols are used.  The symbols only
 463   // appear in the relocations.
 464 }
 465
 466 // The first entry in the PLT for an executable.
 467
 468 unsigned char Output_data_plt_x86_64::first_plt_entry[plt_entry_size] =
 469 {
 470   // From AMD64 ABI Draft 0.98, page 76
 471   0xff, 0x35,   // pushq contents of memory address
 472   0, 0, 0, 0,   // replaced with address of .got + 4
 473   0xff, 0x25,   // jmp indirect
 474   0, 0, 0, 0,   // replaced with address of .got + 8
 475   0x90, 0x90, 0x90, 0x90   // noop (x4)
 476 };
 477
 478 // Subsequent entries in the PLT for an executable.
 479
 480 unsigned char Output_data_plt_x86_64::plt_entry[plt_entry_size] =
 481 {
 482   // From AMD64 ABI Draft 0.98, page 76
 483   0xff, 0x25,   // jmpq indirect
 484   0, 0, 0, 0,   // replaced with address of symbol in .got
 485   0x68,         // pushq immediate
 486   0, 0, 0, 0,   // replaced with offset into relocation table
 487   0xe9,         // jmpq relative
 488   0, 0, 0, 0    // replaced with offset to start of .plt
 489 };
 490
 491 // Write out the PLT.  This uses the hand-coded instructions above,
 492 // and adjusts them as needed.  This is specified by the AMD64 ABI.
 493
 494 void
 495 Output_data_plt_x86_64::do_write(Output_file* of)
 496 {
 497   const off_t offset = this->offset();
 498   const off_t oview_size = this->data_size();
 499   unsigned char* const oview = of->get_output_view(offset, oview_size);
 500
 501   const off_t got_file_offset = this->got_plt_->offset();
 502   const off_t got_size = this->got_plt_->data_size();
 503   unsigned char* const got_view = of->get_output_view(got_file_offset,
 504                                                       got_size);
 505
 506   unsigned char* pov = oview;
 507
 508   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
 509   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 510
 511   memcpy(pov, first_plt_entry, plt_entry_size);
 512   if (!parameters->output_is_shared())
 513     {
 514       // We do a jmp relative to the PC at the end of this instruction.
 515       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 8
 516                                                   - (plt_address + 6));
 517       elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 16
 518                                         - (plt_address + 12));
 519     }
 520   pov += plt_entry_size;
 521
 522   unsigned char* got_pov = got_view;
 523
 524   memset(got_pov, 0, 24);
 525   got_pov += 24;
 526
 527   unsigned int plt_offset = plt_entry_size;
 528   unsigned int got_offset = 24;
 529   const unsigned int count = this->count_;
 530   for (unsigned int plt_index = 0;
 531        plt_index < count;
 532        ++plt_index,
 533          pov += plt_entry_size,
 534          got_pov += 8,
 535          plt_offset += plt_entry_size,
 536          got_offset += 8)
 537     {
 538       // Set and adjust the PLT entry itself.
 539       memcpy(pov, plt_entry, plt_entry_size);
 540       if (parameters->output_is_shared())
 541         // FIXME(csilvers): what's the right thing to write here?
 542         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
 543       else
 544         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 545                                                     (got_address + got_offset
 546                                                      - (plt_address + plt_offset
 547                                                         + 6)));
 548
 549       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_index);
 550       elfcpp::Swap<32, false>::writeval(pov + 12,
 551                                         - (plt_offset + plt_entry_size));
 552
 553       // Set the entry in the GOT.
 554       elfcpp::Swap<64, false>::writeval(got_pov, plt_address + plt_offset + 6);
 555     }
 556
 557   gold_assert(pov - oview == oview_size);
 558   gold_assert(got_pov - got_view == got_size);
 559
 560   of->write_output_view(offset, oview_size, oview);
 561   of->write_output_view(got_file_offset, got_size, got_view);
 562 }
 563
 564 // Create a PLT entry for a global symbol.
 565
 566 void
 567 Target_x86_64::make_plt_entry(Symbol_table* symtab, Layout* layout,
 568                               Symbol* gsym)
 569 {
 570   if (gsym->has_plt_offset())
 571     return;
 572
 573   if (this->plt_ == NULL)
 574     {
 575       // Create the GOT sections first.
 576       this->got_section(symtab, layout);
 577
 578       this->plt_ = new Output_data_plt_x86_64(layout, this->got_plt_);
 579       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 580                                       (elfcpp::SHF_ALLOC
 581                                        | elfcpp::SHF_EXECINSTR),
 582                                       this->plt_);
 583     }
 584
 585   this->plt_->add_entry(gsym);
 586 }
 587
 588 // Handle a relocation against a non-function symbol defined in a
 589 // dynamic object.  The traditional way to handle this is to generate
 590 // a COPY relocation to copy the variable at runtime from the shared
 591 // object into the executable's data segment.  However, this is
 592 // undesirable in general, as if the size of the object changes in the
 593 // dynamic object, the executable will no longer work correctly.  If
 594 // this relocation is in a writable section, then we can create a
 595 // dynamic reloc and the dynamic linker will resolve it to the correct
 596 // address at runtime.  However, we do not want do that if the
 597 // relocation is in a read-only section, as it would prevent the
 598 // readonly segment from being shared.  And if we have to eventually
 599 // generate a COPY reloc, then any dynamic relocations will be
 600 // useless.  So this means that if this is a writable section, we need
 601 // to save the relocation until we see whether we have to create a
 602 // COPY relocation for this symbol for any other relocation.
 603
 604 void
 605 Target_x86_64::copy_reloc(const General_options* options,
 606                           Symbol_table* symtab,
 607                           Layout* layout,
 608                           Sized_relobj<64, false>* object,
 609                           unsigned int data_shndx, Symbol* gsym,
 610                           const elfcpp::Rela<64, false>& rela)
 611 {
 612   Sized_symbol<64>* ssym;
 613   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(64) (gsym
 614                                                         SELECT_SIZE(64));
 615
 616   if (!Copy_relocs<64, false>::need_copy_reloc(options, object,
 617                                                data_shndx, ssym))
 618     {
 619       // So far we do not need a COPY reloc.  Save this relocation.
 620       // If it turns out that we never need a COPY reloc for this
 621       // symbol, then we will emit the relocation.
 622       if (this->copy_relocs_ == NULL)
 623         this->copy_relocs_ = new Copy_relocs<64, false>();
 624       this->copy_relocs_->save(ssym, object, data_shndx, rela);
 625     }
 626   else
 627     {
 628       // Allocate space for this symbol in the .bss section.
 629
 630       elfcpp::Elf_types<64>::Elf_WXword symsize = ssym->symsize();
 631
 632       // There is no defined way to determine the required alignment
 633       // of the symbol.  We pick the alignment based on the size.  We
 634       // set an arbitrary maximum of 256.
 635       unsigned int align;
 636       for (align = 1; align < 512; align <<= 1)
 637         if ((symsize & align) != 0)
 638           break;
 639
 640       if (this->dynbss_ == NULL)
 641         {
 642           this->dynbss_ = new Output_data_space(align);
 643           layout->add_output_section_data(".bss",
 644                                           elfcpp::SHT_NOBITS,
 645                                           (elfcpp::SHF_ALLOC
 646                                            | elfcpp::SHF_WRITE),
 647                                           this->dynbss_);
 648         }
 649
 650       Output_data_space* dynbss = this->dynbss_;
 651
 652       if (align > dynbss->addralign())
 653         dynbss->set_space_alignment(align);
 654
 655       off_t dynbss_size = dynbss->data_size();
 656       dynbss_size = align_address(dynbss_size, align);
 657       off_t offset = dynbss_size;
 658       dynbss->set_space_size(dynbss_size + symsize);
 659
 660       symtab->define_with_copy_reloc(this, ssym, dynbss, offset);
 661
 662       // Add the COPY reloc.
 663       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
 664       rela_dyn->add_global(ssym, elfcpp::R_X86_64_COPY, dynbss, offset, 0);
 665     }
 666 }
 667
 668
 669 // Optimize the TLS relocation type based on what we know about the
 670 // symbol.  IS_FINAL is true if the final address of this symbol is
 671 // known at link time.
 672
 673 tls::Tls_optimization
 674 Target_x86_64::optimize_tls_reloc(bool is_final, int r_type)
 675 {
 676   // If we are generating a shared library, then we can't do anything
 677   // in the linker.
 678   if (parameters->output_is_shared())
 679     return tls::TLSOPT_NONE;
 680
 681   switch (r_type)
 682     {
 683     case elfcpp::R_X86_64_TLSGD:
 684     case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 685     case elfcpp::R_X86_64_TLSDESC_CALL:
 686       // These are General-Dynamic which permits fully general TLS
 687       // access.  Since we know that we are generating an executable,
 688       // we can convert this to Initial-Exec.  If we also know that
 689       // this is a local symbol, we can further switch to Local-Exec.
 690       if (is_final)
 691         return tls::TLSOPT_TO_LE;
 692       return tls::TLSOPT_TO_IE;
 693
 694     case elfcpp::R_X86_64_TLSLD:
 695       // This is Local-Dynamic, which refers to a local symbol in the
 696       // dynamic TLS block.  Since we know that we generating an
 697       // executable, we can switch to Local-Exec.
 698       return tls::TLSOPT_TO_LE;
 699
 700     case elfcpp::R_X86_64_DTPOFF32:
 701     case elfcpp::R_X86_64_DTPOFF64:
 702       // Another Local-Dynamic reloc.
 703       return tls::TLSOPT_TO_LE;
 704
 705     case elfcpp::R_X86_64_GOTTPOFF:
 706       // These are Initial-Exec relocs which get the thread offset
 707       // from the GOT.  If we know that we are linking against the
 708       // local symbol, we can switch to Local-Exec, which links the
 709       // thread offset into the instruction.
 710       if (is_final)
 711         return tls::TLSOPT_TO_LE;
 712       return tls::TLSOPT_NONE;
 713
 714     case elfcpp::R_X86_64_TPOFF32:
 715       // When we already have Local-Exec, there is nothing further we
 716       // can do.
 717       return tls::TLSOPT_NONE;
 718
 719     default:
 720       gold_unreachable();
 721     }
 722 }
 723
 724 // Report an unsupported relocation against a local symbol.
 725
 726 void
 727 Target_x86_64::Scan::unsupported_reloc_local(Sized_relobj<64, false>* object,
 728                                              unsigned int r_type)
 729 {
 730   gold_error(_("%s: unsupported reloc %u against local symbol"),
 731              object->name().c_str(), r_type);
 732 }
 733
 734 // Scan a relocation for a local symbol.
 735
 736 inline void
 737 Target_x86_64::Scan::local(const General_options&,
 738                            Symbol_table* symtab,
 739                            Layout* layout,
 740                            Target_x86_64* target,
 741                            Sized_relobj<64, false>* object,
 742                            unsigned int data_shndx,
 743                            Output_section*,
 744                            const elfcpp::Rela<64, false>& reloc,
 745                            unsigned int r_type,
 746                            const elfcpp::Sym<64, false>&)
 747 {
 748   switch (r_type)
 749     {
 750     case elfcpp::R_X86_64_NONE:
 751     case elfcpp::R_386_GNU_VTINHERIT:
 752     case elfcpp::R_386_GNU_VTENTRY:
 753       break;
 754
 755     case elfcpp::R_X86_64_64:
 756       // If building a shared library (or a position-independent
 757       // executable), we need to create a dynamic relocation for
 758       // this location. The relocation applied at link time will
 759       // apply the link-time value, so we flag the location with
 760       // an R_386_RELATIVE relocation so the dynamic loader can
 761       // relocate it easily.
 762       if (parameters->output_is_position_independent())
 763         {
 764           Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 765           rela_dyn->add_local(object, 0, elfcpp::R_X86_64_RELATIVE,
 766                               data_shndx, reloc.get_r_offset(), 0);
 767         }
 768       break;
 769
 770     case elfcpp::R_X86_64_32:
 771     case elfcpp::R_X86_64_32S:
 772     case elfcpp::R_X86_64_16:
 773     case elfcpp::R_X86_64_8:
 774       // If building a shared library (or a position-independent
 775       // executable), we need to create a dynamic relocation for
 776       // this location. The relocation applied at link time will
 777       // apply the link-time value, so we flag the location with
 778       // an R_386_RELATIVE relocation so the dynamic loader can
 779       // relocate it easily.
 780       if (parameters->output_is_position_independent())
 781         {
 782           Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 783           unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 784           rela_dyn->add_local(object, r_sym, r_type, data_shndx,
 785                               reloc.get_r_offset(),
 786                               reloc.get_r_addend());
 787         }
 788       break;
 789
 790     case elfcpp::R_X86_64_PC64:
 791     case elfcpp::R_X86_64_PC32:
 792     case elfcpp::R_X86_64_PC16:
 793     case elfcpp::R_X86_64_PC8:
 794       break;
 795
 796     case elfcpp::R_X86_64_PLT32:
 797       // Since we know this is a local symbol, we can handle this as a
 798       // PC32 reloc.
 799       break;
 800
 801     case elfcpp::R_X86_64_GOTPC32:
 802     case elfcpp::R_X86_64_GOTOFF64:
 803     case elfcpp::R_X86_64_GOTPC64:
 804     case elfcpp::R_X86_64_PLTOFF64:
 805       // We need a GOT section.
 806       target->got_section(symtab, layout);
 807       // For PLTOFF64, we'd normally want a PLT section, but since we
 808       // know this is a local symbol, no PLT is needed.
 809       break;
 810
 811     case elfcpp::R_X86_64_GOT64:
 812     case elfcpp::R_X86_64_GOT32:
 813     case elfcpp::R_X86_64_GOTPCREL64:
 814     case elfcpp::R_X86_64_GOTPCREL:
 815     case elfcpp::R_X86_64_GOTPLT64:
 816       {
 817         // The symbol requires a GOT entry.
 818         Output_data_got<64, false>* got = target->got_section(symtab, layout);
 819         unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 820         if (got->add_local(object, r_sym))
 821           {
 822             // If we are generating a shared object, we need to add a
 823             // dynamic RELATIVE relocation for this symbol.
 824             if (parameters->output_is_position_independent())
 825               {
 826                 // FIXME: R_X86_64_RELATIVE assumes a 64-bit relocation.
 827                 gold_assert(r_type != elfcpp::R_X86_64_GOT32);
 828
 829                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 830                 rela_dyn->add_local(object, 0, elfcpp::R_X86_64_RELATIVE,
 831                                     data_shndx, reloc.get_r_offset(), 0);
 832               }
 833           }
 834         // For GOTPLT64, we'd normally want a PLT section, but since
 835         // we know this is a local symbol, no PLT is needed.
 836       }
 837       break;
 838
 839     case elfcpp::R_X86_64_COPY:
 840     case elfcpp::R_X86_64_GLOB_DAT:
 841     case elfcpp::R_X86_64_JUMP_SLOT:
 842     case elfcpp::R_X86_64_RELATIVE:
 843       // These are outstanding tls relocs, which are unexpected when linking
 844     case elfcpp::R_X86_64_TPOFF64:
 845     case elfcpp::R_X86_64_DTPMOD64:
 846     case elfcpp::R_X86_64_TLSDESC:
 847       gold_error(_("%s: unexpected reloc %u in object file"),
 848                  object->name().c_str(), r_type);
 849       break;
 850
 851       // These are initial tls relocs, which are expected when linking
 852     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
 853     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
 854     case elfcpp::R_X86_64_TLSDESC_CALL:
 855     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
 856     case elfcpp::R_X86_64_DTPOFF32:
 857     case elfcpp::R_X86_64_DTPOFF64:
 858     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
 859     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
 860       {
 861         bool output_is_shared = parameters->output_is_shared();
 862         const tls::Tls_optimization optimized_type
 863             = Target_x86_64::optimize_tls_reloc(!output_is_shared, r_type);
 864         switch (r_type)
 865           {
 866           case elfcpp::R_X86_64_TLSGD:       // General-dynamic
 867           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 868           case elfcpp::R_X86_64_TLSDESC_CALL:
 869             // FIXME: If not relaxing to LE, we need to generate
 870             // DTPMOD64 and DTPOFF64 relocs.
 871             if (optimized_type != tls::TLSOPT_TO_LE)
 872               unsupported_reloc_local(object, r_type);
 873             break;
 874
 875           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
 876           case elfcpp::R_X86_64_DTPOFF32:
 877           case elfcpp::R_X86_64_DTPOFF64:
 878             // FIXME: If not relaxing to LE, we need to generate a
 879             // DTPMOD64 reloc.
 880             if (optimized_type != tls::TLSOPT_TO_LE)
 881               unsupported_reloc_local(object, r_type);
 882             break;
 883
 884           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
 885             // FIXME: If not relaxing to LE, we need to generate a
 886             // TPOFF64 reloc.
 887             if (optimized_type != tls::TLSOPT_TO_LE)
 888               unsupported_reloc_local(object, r_type);
 889             break;
 890
 891           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
 892             // FIXME: If generating a shared object, we need to copy
 893             // this relocation into the object.
 894             gold_assert(!output_is_shared);
 895             break;
 896
 897           default:
 898             gold_unreachable();
 899           }
 900       }
 901       break;
 902
 903     case elfcpp::R_X86_64_SIZE32:
 904     case elfcpp::R_X86_64_SIZE64:
 905     default:
 906       gold_error(_("%s: unsupported reloc %u against local symbol"),
 907                  object->name().c_str(), r_type);
 908       break;
 909     }
 910 }
 911
 912
 913 // Report an unsupported relocation against a global symbol.
 914
 915 void
 916 Target_x86_64::Scan::unsupported_reloc_global(Sized_relobj<64, false>* object,
 917                                               unsigned int r_type,
 918                                               Symbol* gsym)
 919 {
 920   gold_error(_("%s: unsupported reloc %u against global symbol %s"),
 921              object->name().c_str(), r_type, gsym->demangled_name().c_str());
 922 }
 923
 924 // Scan a relocation for a global symbol.
 925
 926 inline void
 927 Target_x86_64::Scan::global(const General_options& options,
 928                             Symbol_table* symtab,
 929                             Layout* layout,
 930                             Target_x86_64* target,
 931                             Sized_relobj<64, false>* object,
 932                             unsigned int data_shndx,
 933                             Output_section*,
 934                             const elfcpp::Rela<64, false>& reloc,
 935                             unsigned int r_type,
 936                             Symbol* gsym)
 937 {
 938   switch (r_type)
 939     {
 940     case elfcpp::R_X86_64_NONE:
 941     case elfcpp::R_386_GNU_VTINHERIT:
 942     case elfcpp::R_386_GNU_VTENTRY:
 943       break;
 944
 945     case elfcpp::R_X86_64_64:
 946     case elfcpp::R_X86_64_32:
 947     case elfcpp::R_X86_64_32S:
 948     case elfcpp::R_X86_64_16:
 949     case elfcpp::R_X86_64_8:
 950       {
 951         // Make a PLT entry if necessary.
 952         if (gsym->needs_plt_entry())
 953           {
 954             target->make_plt_entry(symtab, layout, gsym);
 955             // Since this is not a PC-relative relocation, we may be
 956             // taking the address of a function. In that case we need to
 957             // set the entry in the dynamic symbol table to the address of
 958             // the PLT entry.
 959             if (gsym->is_from_dynobj())
 960               gsym->set_needs_dynsym_value();
 961           }
 962         // Make a dynamic relocation if necessary.
 963         if (gsym->needs_dynamic_reloc(true, false))
 964           {
 965             if (target->may_need_copy_reloc(gsym))
 966               {
 967                 target->copy_reloc(&options, symtab, layout, object, data_shndx,
 968                                    gsym, reloc);
 969               }
 970             else if (r_type == elfcpp::R_X86_64_64
 971                      && gsym->can_use_relative_reloc(false))
 972               {
 973                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 974                 rela_dyn->add_local(object, 0, elfcpp::R_X86_64_RELATIVE,
 975                                     data_shndx,
 976                                     reloc.get_r_offset(), 0);
 977               }
 978             else
 979               {
 980                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 981                 rela_dyn->add_global(gsym, r_type, object, data_shndx,
 982                                      reloc.get_r_offset(),
 983                                      reloc.get_r_addend());
 984               }
 985           }
 986       }
 987       break;
 988
 989     case elfcpp::R_X86_64_PC64:
 990     case elfcpp::R_X86_64_PC32:
 991     case elfcpp::R_X86_64_PC16:
 992     case elfcpp::R_X86_64_PC8:
 993       {
 994         // Make a PLT entry if necessary.
 995         if (gsym->needs_plt_entry())
 996           target->make_plt_entry(symtab, layout, gsym);
 997         // Make a dynamic relocation if necessary.
 998         bool is_function_call = (gsym->type() == elfcpp::STT_FUNC);
 999         if (gsym->needs_dynamic_reloc(true, is_function_call))
1000           {
1001             if (target->may_need_copy_reloc(gsym))
1002               {
1003                 target->copy_reloc(&options, symtab, layout, object, data_shndx,
1004                                    gsym, reloc);
1005               }
1006             else
1007               {
1008                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
1009                 rela_dyn->add_global(gsym, r_type, object, data_shndx,
1010                                      reloc.get_r_offset(),
1011                                      reloc.get_r_addend());
1012               }
1013           }
1014       }
1015       break;
1016
1017     case elfcpp::R_X86_64_GOT64:
1018     case elfcpp::R_X86_64_GOT32:
1019     case elfcpp::R_X86_64_GOTPCREL64:
1020     case elfcpp::R_X86_64_GOTPCREL:
1021     case elfcpp::R_X86_64_GOTPLT64:
1022       {
1023         // The symbol requires a GOT entry.
1024         Output_data_got<64, false>* got = target->got_section(symtab, layout);
1025         if (got->add_global(gsym))
1026           {
1027             // If this symbol is not fully resolved, we need to add a
1028             // dynamic relocation for it.
1029             if (!gsym->final_value_is_known())
1030               {
1031                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
1032                 if (gsym->is_from_dynobj()
1033                     || gsym->is_preemptible())
1034                   rela_dyn->add_global(gsym, elfcpp::R_X86_64_GLOB_DAT, got,
1035                                        gsym->got_offset(), 0);
1036                 else
1037                   {
1038                     rela_dyn->add_local(object, 0, elfcpp::R_X86_64_RELATIVE,
1039                                         got, gsym->got_offset(), 0);
1040                     // Make sure we write the link-time value to the GOT.
1041                     gsym->set_needs_value_in_got();
1042                   }
1043               }
1044           }
1045         // For GOTPLT64, we also need a PLT entry (but only if the
1046         // symbol is not fully resolved).
1047         if (r_type == elfcpp::R_X86_64_GOTPLT64
1048             && !gsym->final_value_is_known())
1049           target->make_plt_entry(symtab, layout, gsym);
1050       }
1051       break;
1052
1053     case elfcpp::R_X86_64_PLT32:
1054       // If the symbol is fully resolved, this is just a PC32 reloc.
1055       // Otherwise we need a PLT entry.
1056       if (gsym->final_value_is_known())
1057         break;
1058       // If building a shared library, we can also skip the PLT entry
1059       // if the symbol is defined in the output file and is protected
1060       // or hidden.
1061       if (gsym->is_defined()
1062           && !gsym->is_from_dynobj()
1063           && !gsym->is_preemptible())
1064         break;
1065       target->make_plt_entry(symtab, layout, gsym);
1066       break;
1067
1068     case elfcpp::R_X86_64_GOTPC32:
1069     case elfcpp::R_X86_64_GOTOFF64:
1070     case elfcpp::R_X86_64_GOTPC64:
1071     case elfcpp::R_X86_64_PLTOFF64:
1072       // We need a GOT section.
1073       target->got_section(symtab, layout);
1074       // For PLTOFF64, we also need a PLT entry (but only if the
1075       // symbol is not fully resolved).
1076       if (r_type == elfcpp::R_X86_64_PLTOFF64
1077           && !gsym->final_value_is_known())
1078         target->make_plt_entry(symtab, layout, gsym);
1079       break;
1080
1081     case elfcpp::R_X86_64_COPY:
1082     case elfcpp::R_X86_64_GLOB_DAT:
1083     case elfcpp::R_X86_64_JUMP_SLOT:
1084     case elfcpp::R_X86_64_RELATIVE:
1085       // These are outstanding tls relocs, which are unexpected when linking
1086     case elfcpp::R_X86_64_TPOFF64:
1087     case elfcpp::R_X86_64_DTPMOD64:
1088     case elfcpp::R_X86_64_TLSDESC:
1089       gold_error(_("%s: unexpected reloc %u in object file"),
1090                  object->name().c_str(), r_type);
1091       break;
1092
1093       // These are initial tls relocs, which are expected for global()
1094     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1095     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1096     case elfcpp::R_X86_64_TLSDESC_CALL:
1097     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1098     case elfcpp::R_X86_64_DTPOFF32:
1099     case elfcpp::R_X86_64_DTPOFF64:
1100     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1101     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1102       {
1103         const bool is_final = gsym->final_value_is_known();
1104         const tls::Tls_optimization optimized_type
1105             = Target_x86_64::optimize_tls_reloc(is_final, r_type);
1106         switch (r_type)
1107           {
1108           case elfcpp::R_X86_64_TLSGD:       // General-dynamic
1109           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
1110           case elfcpp::R_X86_64_TLSDESC_CALL:
1111             // FIXME: If not relaxing to LE, we need to generate
1112             // DTPMOD64 and DTPOFF64, or TLSDESC, relocs.
1113             if (optimized_type != tls::TLSOPT_TO_LE)
1114               unsupported_reloc_global(object, r_type, gsym);
1115             break;
1116
1117           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
1118           case elfcpp::R_X86_64_DTPOFF32:
1119           case elfcpp::R_X86_64_DTPOFF64:
1120             // FIXME: If not relaxing to LE, we need to generate a
1121             // DTPMOD64 reloc.
1122             if (optimized_type != tls::TLSOPT_TO_LE)
1123               unsupported_reloc_global(object, r_type, gsym);
1124             break;
1125
1126           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
1127             // FIXME: If not relaxing to LE, we need to generate a
1128             // TPOFF64 reloc.
1129             if (optimized_type != tls::TLSOPT_TO_LE)
1130               unsupported_reloc_global(object, r_type, gsym);
1131             break;
1132
1133           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
1134             // FIXME: If generating a shared object, we need to copy
1135             // this relocation into the object.
1136             gold_assert(is_final);
1137             break;
1138
1139           default:
1140             gold_unreachable();
1141           }
1142       }
1143       break;
1144
1145     case elfcpp::R_X86_64_SIZE32:
1146     case elfcpp::R_X86_64_SIZE64:
1147     default:
1148       gold_error(_("%s: unsupported reloc %u against global symbol %s"),
1149                  object->name().c_str(), r_type,
1150                  gsym->demangled_name().c_str());
1151       break;
1152     }
1153 }
1154
1155 // Scan relocations for a section.
1156
1157 void
1158 Target_x86_64::scan_relocs(const General_options& options,
1159                            Symbol_table* symtab,
1160                            Layout* layout,
1161                            Sized_relobj<64, false>* object,
1162                            unsigned int data_shndx,
1163                            unsigned int sh_type,
1164                            const unsigned char* prelocs,
1165                            size_t reloc_count,
1166                            Output_section* output_section,
1167                            bool needs_special_offset_handling,
1168                            size_t local_symbol_count,
1169                            const unsigned char* plocal_symbols)
1170 {
1171   if (sh_type == elfcpp::SHT_REL)
1172     {
1173       gold_error(_("%s: unsupported REL reloc section"),
1174                  object->name().c_str());
1175       return;
1176     }
1177
1178   gold::scan_relocs<64, false, Target_x86_64, elfcpp::SHT_RELA,
1179       Target_x86_64::Scan>(
1180     options,
1181     symtab,
1182     layout,
1183     this,
1184     object,
1185     data_shndx,
1186     prelocs,
1187     reloc_count,
1188     output_section,
1189     needs_special_offset_handling,
1190     local_symbol_count,
1191     plocal_symbols);
1192 }
1193
1194 // Finalize the sections.
1195
1196 void
1197 Target_x86_64::do_finalize_sections(Layout* layout)
1198 {
1199   // Fill in some more dynamic tags.
1200   Output_data_dynamic* const odyn = layout->dynamic_data();
1201   if (odyn != NULL)
1202     {
1203       if (this->got_plt_ != NULL)
1204         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1205
1206       if (this->plt_ != NULL)
1207         {
1208           const Output_data* od = this->plt_->rel_plt();
1209           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1210           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1211           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_RELA);
1212         }
1213
1214       if (this->rela_dyn_ != NULL)
1215         {
1216           const Output_data* od = this->rela_dyn_;
1217           odyn->add_section_address(elfcpp::DT_RELA, od);
1218           odyn->add_section_size(elfcpp::DT_RELASZ, od);
1219           odyn->add_constant(elfcpp::DT_RELAENT,
1220                              elfcpp::Elf_sizes<64>::rela_size);
1221         }
1222
1223       if (!parameters->output_is_shared())
1224         {
1225           // The value of the DT_DEBUG tag is filled in by the dynamic
1226           // linker at run time, and used by the debugger.
1227           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1228         }
1229     }
1230
1231   // Emit any relocs we saved in an attempt to avoid generating COPY
1232   // relocs.
1233   if (this->copy_relocs_ == NULL)
1234     return;
1235   if (this->copy_relocs_->any_to_emit())
1236     {
1237       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
1238       this->copy_relocs_->emit(rela_dyn);
1239     }
1240   delete this->copy_relocs_;
1241   this->copy_relocs_ = NULL;
1242 }
1243
1244 // Perform a relocation.
1245
1246 inline bool
1247 Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo,
1248                                   Target_x86_64* target,
1249                                   size_t relnum,
1250                                   const elfcpp::Rela<64, false>& rela,
1251                                   unsigned int r_type,
1252                                   const Sized_symbol<64>* gsym,
1253                                   const Symbol_value<64>* psymval,
1254                                   unsigned char* view,
1255                                   elfcpp::Elf_types<64>::Elf_Addr address,
1256                                   off_t view_size)
1257 {
1258   if (this->skip_call_tls_get_addr_)
1259     {
1260       if (r_type != elfcpp::R_X86_64_PLT32
1261           || gsym == NULL
1262           || strcmp(gsym->name(), "__tls_get_addr") != 0)
1263         {
1264           gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1265                                  _("missing expected TLS relocation"));
1266         }
1267       else
1268         {
1269           this->skip_call_tls_get_addr_ = false;
1270           return false;
1271         }
1272     }
1273
1274   // Pick the value to use for symbols defined in shared objects.
1275   Symbol_value<64> symval;
1276   if (gsym != NULL
1277       && (gsym->is_from_dynobj()
1278           || (parameters->output_is_shared()
1279               && gsym->is_preemptible()))
1280       && gsym->has_plt_offset())
1281     {
1282       symval.set_output_value(target->plt_section()->address()
1283                               + gsym->plt_offset());
1284       psymval = &symval;
1285     }
1286
1287   const Sized_relobj<64, false>* object = relinfo->object;
1288   const elfcpp::Elf_Xword addend = rela.get_r_addend();
1289
1290   // Get the GOT offset if needed.
1291   // The GOT pointer points to the end of the GOT section.
1292   // We need to subtract the size of the GOT section to get
1293   // the actual offset to use in the relocation.
1294   bool have_got_offset = false;
1295   unsigned int got_offset = 0;
1296   switch (r_type)
1297     {
1298     case elfcpp::R_X86_64_GOT32:
1299     case elfcpp::R_X86_64_GOT64:
1300     case elfcpp::R_X86_64_GOTPLT64:
1301     case elfcpp::R_X86_64_GOTPCREL:
1302     case elfcpp::R_X86_64_GOTPCREL64:
1303       if (gsym != NULL)
1304         {
1305           gold_assert(gsym->has_got_offset());
1306           got_offset = gsym->got_offset() - target->got_size();
1307         }
1308       else
1309         {
1310           unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1311           got_offset = object->local_got_offset(r_sym) - target->got_size();
1312         }
1313       have_got_offset = true;
1314       break;
1315
1316     default:
1317       break;
1318     }
1319
1320   switch (r_type)
1321     {
1322     case elfcpp::R_X86_64_NONE:
1323     case elfcpp::R_386_GNU_VTINHERIT:
1324     case elfcpp::R_386_GNU_VTENTRY:
1325       break;
1326
1327     case elfcpp::R_X86_64_64:
1328       Relocate_functions<64, false>::rela64(view, object, psymval, addend);
1329       break;
1330
1331     case elfcpp::R_X86_64_PC64:
1332       Relocate_functions<64, false>::pcrela64(view, object, psymval, addend,
1333                                               address);
1334       break;
1335
1336     case elfcpp::R_X86_64_32:
1337       // FIXME: we need to verify that value + addend fits into 32 bits:
1338       //    uint64_t x = value + addend;
1339       //    x == static_cast<uint64_t>(static_cast<uint32_t>(x))
1340       // Likewise for other <=32-bit relocations (but see R_X86_64_32S).
1341       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1342       break;
1343
1344     case elfcpp::R_X86_64_32S:
1345       // FIXME: we need to verify that value + addend fits into 32 bits:
1346       //    int64_t x = value + addend;   // note this quantity is signed!
1347       //    x == static_cast<int64_t>(static_cast<int32_t>(x))
1348       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1349       break;
1350
1351     case elfcpp::R_X86_64_PC32:
1352       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1353                                               address);
1354       break;
1355
1356     case elfcpp::R_X86_64_16:
1357       Relocate_functions<64, false>::rela16(view, object, psymval, addend);
1358       break;
1359
1360     case elfcpp::R_X86_64_PC16:
1361       Relocate_functions<64, false>::pcrela16(view, object, psymval, addend,
1362                                               address);
1363       break;
1364
1365     case elfcpp::R_X86_64_8:
1366       Relocate_functions<64, false>::rela8(view, object, psymval, addend);
1367       break;
1368
1369     case elfcpp::R_X86_64_PC8:
1370       Relocate_functions<64, false>::pcrela8(view, object, psymval, addend,
1371                                              address);
1372       break;
1373
1374     case elfcpp::R_X86_64_PLT32:
1375       gold_assert(gsym == NULL
1376                   || gsym->has_plt_offset()
1377                   || gsym->final_value_is_known());
1378       // Note: while this code looks the same as for R_X86_64_PC32, it
1379       // behaves differently because psymval was set to point to
1380       // the PLT entry, rather than the symbol, in Scan::global().
1381       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1382                                               address);
1383       break;
1384
1385     case elfcpp::R_X86_64_PLTOFF64:
1386       {
1387         gold_assert(gsym);
1388         gold_assert(gsym->has_plt_offset()
1389                     || gsym->final_value_is_known());
1390         elfcpp::Elf_types<64>::Elf_Addr got_address;
1391         got_address = target->got_section(NULL, NULL)->address();
1392         Relocate_functions<64, false>::rela64(view, object, psymval,
1393                                               addend - got_address);
1394       }
1395
1396     case elfcpp::R_X86_64_GOT32:
1397       gold_assert(have_got_offset);
1398       Relocate_functions<64, false>::rela32(view, got_offset, addend);
1399       break;
1400
1401     case elfcpp::R_X86_64_GOTPC32:
1402       {
1403         gold_assert(gsym);
1404         elfcpp::Elf_types<64>::Elf_Addr value;
1405         value = target->got_plt_section()->address();
1406         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1407       }
1408       break;
1409
1410     case elfcpp::R_X86_64_GOT64:
1411       // The ABI doc says "Like GOT64, but indicates a PLT entry is needed."
1412       // Since we always add a PLT entry, this is equivalent.
1413     case elfcpp::R_X86_64_GOTPLT64:
1414       gold_assert(have_got_offset);
1415       Relocate_functions<64, false>::rela64(view, got_offset, addend);
1416       break;
1417
1418     case elfcpp::R_X86_64_GOTPC64:
1419       {
1420         gold_assert(gsym);
1421         elfcpp::Elf_types<64>::Elf_Addr value;
1422         value = target->got_plt_section()->address();
1423         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1424       }
1425       break;
1426
1427     case elfcpp::R_X86_64_GOTOFF64:
1428       {
1429         elfcpp::Elf_types<64>::Elf_Addr value;
1430         value = (psymval->value(object, 0)
1431                  - target->got_plt_section()->address());
1432         Relocate_functions<64, false>::rela64(view, value, addend);
1433       }
1434       break;
1435
1436     case elfcpp::R_X86_64_GOTPCREL:
1437       {
1438         gold_assert(have_got_offset);
1439         elfcpp::Elf_types<64>::Elf_Addr value;
1440         value = target->got_plt_section()->address() + got_offset;
1441         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1442       }
1443       break;
1444
1445     case elfcpp::R_X86_64_GOTPCREL64:
1446       {
1447         gold_assert(have_got_offset);
1448         elfcpp::Elf_types<64>::Elf_Addr value;
1449         value = target->got_plt_section()->address() + got_offset;
1450         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1451       }
1452       break;
1453
1454     case elfcpp::R_X86_64_COPY:
1455     case elfcpp::R_X86_64_GLOB_DAT:
1456     case elfcpp::R_X86_64_JUMP_SLOT:
1457     case elfcpp::R_X86_64_RELATIVE:
1458       // These are outstanding tls relocs, which are unexpected when linking
1459     case elfcpp::R_X86_64_TPOFF64:
1460     case elfcpp::R_X86_64_DTPMOD64:
1461     case elfcpp::R_X86_64_TLSDESC:
1462       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1463                              _("unexpected reloc %u in object file"),
1464                              r_type);
1465       break;
1466
1467       // These are initial tls relocs, which are expected when linking
1468     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1469     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1470     case elfcpp::R_X86_64_TLSDESC_CALL:
1471     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1472     case elfcpp::R_X86_64_DTPOFF32:
1473     case elfcpp::R_X86_64_DTPOFF64:
1474     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1475     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1476       this->relocate_tls(relinfo, relnum, rela, r_type, gsym, psymval, view,
1477                          address, view_size);
1478       break;
1479
1480     case elfcpp::R_X86_64_SIZE32:
1481     case elfcpp::R_X86_64_SIZE64:
1482     default:
1483       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1484                              _("unsupported reloc %u"),
1485                              r_type);
1486       break;
1487     }
1488
1489   return true;
1490 }
1491
1492 // Perform a TLS relocation.
1493
1494 inline void
1495 Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo,
1496                                       size_t relnum,
1497                                       const elfcpp::Rela<64, false>& rela,
1498                                       unsigned int r_type,
1499                                       const Sized_symbol<64>* gsym,
1500                                       const Symbol_value<64>* psymval,
1501                                       unsigned char* view,
1502                                       elfcpp::Elf_types<64>::Elf_Addr,
1503                                       off_t view_size)
1504 {
1505   Output_segment* tls_segment = relinfo->layout->tls_segment();
1506   if (tls_segment == NULL)
1507     {
1508       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1509                              _("TLS reloc but no TLS segment"));
1510       return;
1511     }
1512
1513   elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0);
1514
1515   const bool is_final = (gsym == NULL
1516                          ? !parameters->output_is_position_independent()
1517                          : gsym->final_value_is_known());
1518   const tls::Tls_optimization optimized_type
1519       = Target_x86_64::optimize_tls_reloc(is_final, r_type);
1520   switch (r_type)
1521     {
1522     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1523     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1524     case elfcpp::R_X86_64_TLSDESC_CALL:
1525       if (optimized_type == tls::TLSOPT_TO_LE)
1526         {
1527           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1528                              rela, r_type, value, view,
1529                              view_size);
1530           break;
1531         }
1532       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1533                              _("unsupported reloc %u"), r_type);
1534       break;
1535
1536     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1537       if (optimized_type == tls::TLSOPT_TO_LE)
1538         {
1539           this->tls_ld_to_le(relinfo, relnum, tls_segment, rela, r_type,
1540                              value, view, view_size);
1541           break;
1542         }
1543       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1544                              _("unsupported reloc %u"), r_type);
1545       break;
1546
1547     case elfcpp::R_X86_64_DTPOFF32:
1548       if (optimized_type == tls::TLSOPT_TO_LE)
1549         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1550       else
1551         value = value - tls_segment->vaddr();
1552       Relocate_functions<64, false>::rel32(view, value);
1553       break;
1554
1555     case elfcpp::R_X86_64_DTPOFF64:
1556       if (optimized_type == tls::TLSOPT_TO_LE)
1557         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1558       else
1559         value = value - tls_segment->vaddr();
1560       Relocate_functions<64, false>::rel64(view, value);
1561       break;
1562
1563     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1564       if (optimized_type == tls::TLSOPT_TO_LE)
1565         {
1566           Target_x86_64::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1567                                                 rela, r_type, value, view,
1568                                                 view_size);
1569           break;
1570         }
1571       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1572                              _("unsupported reloc type %u"),
1573                              r_type);
1574       break;
1575
1576     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1577       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1578       Relocate_functions<64, false>::rel32(view, value);
1579       break;
1580     }
1581 }
1582
1583 // Do a relocation in which we convert a TLS General-Dynamic to a
1584 // Local-Exec.
1585
1586 inline void
1587 Target_x86_64::Relocate::tls_gd_to_le(const Relocate_info<64, false>* relinfo,
1588                                       size_t relnum,
1589                                       Output_segment* tls_segment,
1590                                       const elfcpp::Rela<64, false>& rela,
1591                                       unsigned int,
1592                                       elfcpp::Elf_types<64>::Elf_Addr value,
1593                                       unsigned char* view,
1594                                       off_t view_size)
1595 {
1596   // .byte 0x66; leaq foo@tlsgd(%rip),%rdi;
1597   // .word 0x6666; rex64; call __tls_get_addr
1598   // ==> movq %fs:0,%rax; leaq x@tpoff(%rax),%rax
1599
1600   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4);
1601   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12);
1602
1603   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1604                  (memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0));
1605   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1606                  (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0));
1607
1608   memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x8d\x80\0\0\0\0", 16);
1609
1610   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1611   Relocate_functions<64, false>::rela32(view + 8, value, 0);
1612
1613   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1614   // We can skip it.
1615   this->skip_call_tls_get_addr_ = true;
1616 }
1617
1618 inline void
1619 Target_x86_64::Relocate::tls_ld_to_le(const Relocate_info<64, false>* relinfo,
1620                                       size_t relnum,
1621                                       Output_segment*,
1622                                       const elfcpp::Rela<64, false>& rela,
1623                                       unsigned int,
1624                                       elfcpp::Elf_types<64>::Elf_Addr,
1625                                       unsigned char* view,
1626                                       off_t view_size)
1627 {
1628   // leaq foo@tlsld(%rip),%rdi; call __tls_get_addr@plt;
1629   // ... leq foo@dtpoff(%rax),%reg
1630   // ==> .word 0x6666; .byte 0x66; movq %fs:0,%rax ... leaq x@tpoff(%rax),%rdx
1631
1632   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1633   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 9);
1634
1635   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1636                  view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x3d);
1637
1638   tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[4] == 0xe8);
1639
1640   memcpy(view - 3, "\x66\x66\x66\x64\x48\x8b\x04\x25\0\0\0\0", 12);
1641
1642   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1643   // We can skip it.
1644   this->skip_call_tls_get_addr_ = true;
1645 }
1646
1647 // Do a relocation in which we convert a TLS Initial-Exec to a
1648 // Local-Exec.
1649
1650 inline void
1651 Target_x86_64::Relocate::tls_ie_to_le(const Relocate_info<64, false>* relinfo,
1652                                       size_t relnum,
1653                                       Output_segment* tls_segment,
1654                                       const elfcpp::Rela<64, false>& rela,
1655                                       unsigned int,
1656                                       elfcpp::Elf_types<64>::Elf_Addr value,
1657                                       unsigned char* view,
1658                                       off_t view_size)
1659 {
1660   // We need to examine the opcodes to figure out which instruction we
1661   // are looking at.
1662
1663   // movq foo@gottpoff(%rip),%reg  ==>  movq $YY,%reg
1664   // addq foo@gottpoff(%rip),%reg  ==>  addq $YY,%reg
1665
1666   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1667   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 4);
1668
1669   unsigned char op1 = view[-3];
1670   unsigned char op2 = view[-2];
1671   unsigned char op3 = view[-1];
1672   unsigned char reg = op3 >> 3;
1673
1674   if (op2 == 0x8b)
1675     {
1676       // movq
1677       if (op1 == 0x4c)
1678         view[-3] = 0x49;
1679       view[-2] = 0xc7;
1680       view[-1] = 0xc0 | reg;
1681     }
1682   else if (reg == 4)
1683     {
1684       // Special handling for %rsp.
1685       if (op1 == 0x4c)
1686         view[-3] = 0x49;
1687       view[-2] = 0x81;
1688       view[-1] = 0xc0 | reg;
1689     }
1690   else
1691     {
1692       // addq
1693       if (op1 == 0x4c)
1694         view[-3] = 0x4d;
1695       view[-2] = 0x8d;
1696       view[-1] = 0x80 | reg | (reg << 3);
1697     }
1698
1699   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1700   Relocate_functions<64, false>::rela32(view, value, 0);
1701 }
1702
1703 // Relocate section data.
1704
1705 void
1706 Target_x86_64::relocate_section(const Relocate_info<64, false>* relinfo,
1707                                 unsigned int sh_type,
1708                                 const unsigned char* prelocs,
1709                                 size_t reloc_count,
1710                                 Output_section* output_section,
1711                                 bool needs_special_offset_handling,
1712                                 unsigned char* view,
1713                                 elfcpp::Elf_types<64>::Elf_Addr address,
1714                                 off_t view_size)
1715 {
1716   gold_assert(sh_type == elfcpp::SHT_RELA);
1717
1718   gold::relocate_section<64, false, Target_x86_64, elfcpp::SHT_RELA,
1719                          Target_x86_64::Relocate>(
1720     relinfo,
1721     this,
1722     prelocs,
1723     reloc_count,
1724     output_section,
1725     needs_special_offset_handling,
1726     view,
1727     address,
1728     view_size);
1729 }
1730
1731 // Return the value to use for a dynamic which requires special
1732 // treatment.  This is how we support equality comparisons of function
1733 // pointers across shared library boundaries, as described in the
1734 // processor specific ABI supplement.
1735
1736 uint64_t
1737 Target_x86_64::do_dynsym_value(const Symbol* gsym) const
1738 {
1739   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1740   return this->plt_section()->address() + gsym->plt_offset();
1741 }
1742
1743 // Return a string used to fill a code section with nops to take up
1744 // the specified length.
1745
1746 std::string
1747 Target_x86_64::do_code_fill(off_t length)
1748 {
1749   if (length >= 16)
1750     {
1751       // Build a jmpq instruction to skip over the bytes.
1752       unsigned char jmp[5];
1753       jmp[0] = 0xe9;
1754       elfcpp::Swap_unaligned<64, false>::writeval(jmp + 1, length - 5);
1755       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1756               + std::string(length - 5, '\0'));
1757     }
1758
1759   // Nop sequences of various lengths.
1760   const char nop1[1] = { 0x90 };                   // nop
1761   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1762   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1763   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1764   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1765                          0x00 };                   // leal 0(%esi,1),%esi
1766   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1767                          0x00, 0x00 };
1768   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1769                          0x00, 0x00, 0x00 };
1770   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1771                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1772   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1773                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1774                          0x00 };
1775   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1776                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1777                            0x00, 0x00 };
1778   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1779                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1780                            0x00, 0x00, 0x00 };
1781   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1782                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1783                            0x00, 0x00, 0x00, 0x00 };
1784   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1785                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1786                            0x27, 0x00, 0x00, 0x00,
1787                            0x00 };
1788   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1789                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1790                            0xbc, 0x27, 0x00, 0x00,
1791                            0x00, 0x00 };
1792   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1793                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1794                            0x90, 0x90, 0x90, 0x90,
1795                            0x90, 0x90, 0x90 };
1796
1797   const char* nops[16] = {
1798     NULL,
1799     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1800     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1801   };
1802
1803   return std::string(nops[length], length);
1804 }
1805
1806 // The selector for x86_64 object files.
1807
1808 class Target_selector_x86_64 : public Target_selector
1809 {
1810 public:
1811   Target_selector_x86_64()
1812     : Target_selector(elfcpp::EM_X86_64, 64, false)
1813   { }
1814
1815   Target*
1816   recognize(int machine, int osabi, int abiversion);
1817
1818  private:
1819   Target_x86_64* target_;
1820 };
1821
1822 // Recognize an x86_64 object file when we already know that the machine
1823 // number is EM_X86_64.
1824
1825 Target*
1826 Target_selector_x86_64::recognize(int, int, int)
1827 {
1828   if (this->target_ == NULL)
1829     this->target_ = new Target_x86_64();
1830   return this->target_;
1831 }
1832
1833 Target_selector_x86_64 target_selector_x86_64;
1834
1835 } // End anonymous namespace.