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>*, Target_x86_64*,
 190                  size_t relnum, 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_ie(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 General-Dynamic to Local-Exec transition.
 205     inline void
 206     tls_gd_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 Local-Dynamic to Local-Exec transition.
 214     inline void
 215     tls_ld_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     // Do a TLS Initial-Exec to Local-Exec transition.
 223     static inline void
 224     tls_ie_to_le(const Relocate_info<64, false>*, size_t relnum,
 225                  Output_segment* tls_segment,
 226                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 227                  elfcpp::Elf_types<64>::Elf_Addr value,
 228                  unsigned char* view,
 229                  off_t view_size);
 230
 231     // This is set if we should skip the next reloc, which should be a
 232     // PLT32 reloc against ___tls_get_addr.
 233     bool skip_call_tls_get_addr_;
 234   };
 235
 236   // Adjust TLS relocation type based on the options and whether this
 237   // is a local symbol.
 238   static tls::Tls_optimization
 239   optimize_tls_reloc(bool is_final, int r_type);
 240
 241   // Get the GOT section, creating it if necessary.
 242   Output_data_got<64, false>*
 243   got_section(Symbol_table*, Layout*);
 244
 245   // Get the GOT PLT section.
 246   Output_data_space*
 247   got_plt_section() const
 248   {
 249     gold_assert(this->got_plt_ != NULL);
 250     return this->got_plt_;
 251   }
 252
 253   // Create a PLT entry for a global symbol.
 254   void
 255   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 256
 257   // Get the PLT section.
 258   Output_data_plt_x86_64*
 259   plt_section() const
 260   {
 261     gold_assert(this->plt_ != NULL);
 262     return this->plt_;
 263   }
 264
 265   // Get the dynamic reloc section, creating it if necessary.
 266   Reloc_section*
 267   rela_dyn_section(Layout*);
 268
 269   // Return true if the symbol may need a COPY relocation.
 270   // References from an executable object to non-function symbols
 271   // defined in a dynamic object may need a COPY relocation.
 272   bool
 273   may_need_copy_reloc(Symbol* gsym)
 274   {
 275     return (!parameters->output_is_shared()
 276             && gsym->is_from_dynobj()
 277             && gsym->type() != elfcpp::STT_FUNC);
 278   }
 279
 280   // Copy a relocation against a global symbol.
 281   void
 282   copy_reloc(const General_options*, Symbol_table*, Layout*,
 283              Sized_relobj<64, false>*, unsigned int,
 284              Output_section*, Symbol*, const elfcpp::Rela<64, false>&);
 285
 286   // Information about this specific target which we pass to the
 287   // general Target structure.
 288   static const Target::Target_info x86_64_info;
 289
 290   // The GOT section.
 291   Output_data_got<64, false>* got_;
 292   // The PLT section.
 293   Output_data_plt_x86_64* plt_;
 294   // The GOT PLT section.
 295   Output_data_space* got_plt_;
 296   // The dynamic reloc section.
 297   Reloc_section* rela_dyn_;
 298   // Relocs saved to avoid a COPY reloc.
 299   Copy_relocs<64, false>* copy_relocs_;
 300   // Space for variables copied with a COPY reloc.
 301   Output_data_space* dynbss_;
 302 };
 303
 304 const Target::Target_info Target_x86_64::x86_64_info =
 305 {
 306   64,                   // size
 307   false,                // is_big_endian
 308   elfcpp::EM_X86_64,    // machine_code
 309   false,                // has_make_symbol
 310   false,                // has_resolve
 311   true,                 // has_code_fill
 312   true,                 // is_default_stack_executable
 313   "/lib/ld64.so.1",     // program interpreter
 314   0x400000,             // default_text_segment_address
 315   0x1000,               // abi_pagesize
 316   0x1000                // common_pagesize
 317 };
 318
 319 // Get the GOT section, creating it if necessary.
 320
 321 Output_data_got<64, false>*
 322 Target_x86_64::got_section(Symbol_table* symtab, Layout* layout)
 323 {
 324   if (this->got_ == NULL)
 325     {
 326       gold_assert(symtab != NULL && layout != NULL);
 327
 328       this->got_ = new Output_data_got<64, false>();
 329
 330       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 331                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 332                                       this->got_);
 333
 334       // The old GNU linker creates a .got.plt section.  We just
 335       // create another set of data in the .got section.  Note that we
 336       // always create a PLT if we create a GOT, although the PLT
 337       // might be empty.
 338       this->got_plt_ = new Output_data_space(8);
 339       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 340                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 341                                       this->got_plt_);
 342
 343       // The first three entries are reserved.
 344       this->got_plt_->set_current_data_size(3 * 8);
 345
 346       // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
 347       symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
 348                                     this->got_plt_,
 349                                     0, 0, elfcpp::STT_OBJECT,
 350                                     elfcpp::STB_LOCAL,
 351                                     elfcpp::STV_HIDDEN, 0,
 352                                     false, false);
 353     }
 354
 355   return this->got_;
 356 }
 357
 358 // Get the dynamic reloc section, creating it if necessary.
 359
 360 Target_x86_64::Reloc_section*
 361 Target_x86_64::rela_dyn_section(Layout* layout)
 362 {
 363   if (this->rela_dyn_ == NULL)
 364     {
 365       gold_assert(layout != NULL);
 366       this->rela_dyn_ = new Reloc_section();
 367       layout->add_output_section_data(".rela.dyn", elfcpp::SHT_RELA,
 368                                       elfcpp::SHF_ALLOC, this->rela_dyn_);
 369     }
 370   return this->rela_dyn_;
 371 }
 372
 373 // A class to handle the PLT data.
 374
 375 class Output_data_plt_x86_64 : public Output_section_data
 376 {
 377  public:
 378   typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
 379
 380   Output_data_plt_x86_64(Layout*, Output_data_space*);
 381
 382   // Add an entry to the PLT.
 383   void
 384   add_entry(Symbol* gsym);
 385
 386   // Return the .rel.plt section data.
 387   const Reloc_section*
 388   rel_plt() const
 389   { return this->rel_; }
 390
 391  protected:
 392   void
 393   do_adjust_output_section(Output_section* os);
 394
 395  private:
 396   // The size of an entry in the PLT.
 397   static const int plt_entry_size = 16;
 398
 399   // The first entry in the PLT.
 400   // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same
 401   // procedure linkage table for both programs and shared objects."
 402   static unsigned char first_plt_entry[plt_entry_size];
 403
 404   // Other entries in the PLT for an executable.
 405   static unsigned char plt_entry[plt_entry_size];
 406
 407   // Set the final size.
 408   void
 409   set_final_data_size()
 410   { this->set_data_size((this->count_ + 1) * plt_entry_size); }
 411
 412   // Write out the PLT data.
 413   void
 414   do_write(Output_file*);
 415
 416   // The reloc section.
 417   Reloc_section* rel_;
 418   // The .got.plt section.
 419   Output_data_space* got_plt_;
 420   // The number of PLT entries.
 421   unsigned int count_;
 422 };
 423
 424 // Create the PLT section.  The ordinary .got section is an argument,
 425 // since we need to refer to the start.  We also create our own .got
 426 // section just for PLT entries.
 427
 428 Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout,
 429                                                Output_data_space* got_plt)
 430   : Output_section_data(8), got_plt_(got_plt), count_(0)
 431 {
 432   this->rel_ = new Reloc_section();
 433   layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
 434                                   elfcpp::SHF_ALLOC, this->rel_);
 435 }
 436
 437 void
 438 Output_data_plt_x86_64::do_adjust_output_section(Output_section* os)
 439 {
 440   // UnixWare sets the entsize of .plt to 4, and so does the old GNU
 441   // linker, and so do we.
 442   os->set_entsize(4);
 443 }
 444
 445 // Add an entry to the PLT.
 446
 447 void
 448 Output_data_plt_x86_64::add_entry(Symbol* gsym)
 449 {
 450   gold_assert(!gsym->has_plt_offset());
 451
 452   // Note that when setting the PLT offset we skip the initial
 453   // reserved PLT entry.
 454   gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
 455
 456   ++this->count_;
 457
 458   off_t got_offset = this->got_plt_->current_data_size();
 459
 460   // Every PLT entry needs a GOT entry which points back to the PLT
 461   // entry (this will be changed by the dynamic linker, normally
 462   // lazily when the function is called).
 463   this->got_plt_->set_current_data_size(got_offset + 8);
 464
 465   // Every PLT entry needs a reloc.
 466   gsym->set_needs_dynsym_entry();
 467   this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_,
 468                          got_offset, 0);
 469
 470   // Note that we don't need to save the symbol.  The contents of the
 471   // PLT are independent of which symbols are used.  The symbols only
 472   // appear in the relocations.
 473 }
 474
 475 // The first entry in the PLT for an executable.
 476
 477 unsigned char Output_data_plt_x86_64::first_plt_entry[plt_entry_size] =
 478 {
 479   // From AMD64 ABI Draft 0.98, page 76
 480   0xff, 0x35,   // pushq contents of memory address
 481   0, 0, 0, 0,   // replaced with address of .got + 8
 482   0xff, 0x25,   // jmp indirect
 483   0, 0, 0, 0,   // replaced with address of .got + 16
 484   0x90, 0x90, 0x90, 0x90   // noop (x4)
 485 };
 486
 487 // Subsequent entries in the PLT for an executable.
 488
 489 unsigned char Output_data_plt_x86_64::plt_entry[plt_entry_size] =
 490 {
 491   // From AMD64 ABI Draft 0.98, page 76
 492   0xff, 0x25,   // jmpq indirect
 493   0, 0, 0, 0,   // replaced with address of symbol in .got
 494   0x68,         // pushq immediate
 495   0, 0, 0, 0,   // replaced with offset into relocation table
 496   0xe9,         // jmpq relative
 497   0, 0, 0, 0    // replaced with offset to start of .plt
 498 };
 499
 500 // Write out the PLT.  This uses the hand-coded instructions above,
 501 // and adjusts them as needed.  This is specified by the AMD64 ABI.
 502
 503 void
 504 Output_data_plt_x86_64::do_write(Output_file* of)
 505 {
 506   const off_t offset = this->offset();
 507   const off_t oview_size = this->data_size();
 508   unsigned char* const oview = of->get_output_view(offset, oview_size);
 509
 510   const off_t got_file_offset = this->got_plt_->offset();
 511   const off_t got_size = this->got_plt_->data_size();
 512   unsigned char* const got_view = of->get_output_view(got_file_offset,
 513                                                       got_size);
 514
 515   unsigned char* pov = oview;
 516
 517   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
 518   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 519
 520   memcpy(pov, first_plt_entry, plt_entry_size);
 521   // We do a jmp relative to the PC at the end of this instruction.
 522   elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 8
 523                                               - (plt_address + 6));
 524   elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 16
 525                                     - (plt_address + 12));
 526   pov += plt_entry_size;
 527
 528   unsigned char* got_pov = got_view;
 529
 530   memset(got_pov, 0, 24);
 531   got_pov += 24;
 532
 533   unsigned int plt_offset = plt_entry_size;
 534   unsigned int got_offset = 24;
 535   const unsigned int count = this->count_;
 536   for (unsigned int plt_index = 0;
 537        plt_index < count;
 538        ++plt_index,
 539          pov += plt_entry_size,
 540          got_pov += 8,
 541          plt_offset += plt_entry_size,
 542          got_offset += 8)
 543     {
 544       // Set and adjust the PLT entry itself.
 545       memcpy(pov, plt_entry, plt_entry_size);
 546       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 547                                                   (got_address + got_offset
 548                                                    - (plt_address + plt_offset
 549                                                       + 6)));
 550
 551       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_index);
 552       elfcpp::Swap<32, false>::writeval(pov + 12,
 553                                         - (plt_offset + plt_entry_size));
 554
 555       // Set the entry in the GOT.
 556       elfcpp::Swap<64, false>::writeval(got_pov, plt_address + plt_offset + 6);
 557     }
 558
 559   gold_assert(pov - oview == oview_size);
 560   gold_assert(got_pov - got_view == got_size);
 561
 562   of->write_output_view(offset, oview_size, oview);
 563   of->write_output_view(got_file_offset, got_size, got_view);
 564 }
 565
 566 // Create a PLT entry for a global symbol.
 567
 568 void
 569 Target_x86_64::make_plt_entry(Symbol_table* symtab, Layout* layout,
 570                               Symbol* gsym)
 571 {
 572   if (gsym->has_plt_offset())
 573     return;
 574
 575   if (this->plt_ == NULL)
 576     {
 577       // Create the GOT sections first.
 578       this->got_section(symtab, layout);
 579
 580       this->plt_ = new Output_data_plt_x86_64(layout, this->got_plt_);
 581       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 582                                       (elfcpp::SHF_ALLOC
 583                                        | elfcpp::SHF_EXECINSTR),
 584                                       this->plt_);
 585     }
 586
 587   this->plt_->add_entry(gsym);
 588 }
 589
 590 // Handle a relocation against a non-function symbol defined in a
 591 // dynamic object.  The traditional way to handle this is to generate
 592 // a COPY relocation to copy the variable at runtime from the shared
 593 // object into the executable's data segment.  However, this is
 594 // undesirable in general, as if the size of the object changes in the
 595 // dynamic object, the executable will no longer work correctly.  If
 596 // this relocation is in a writable section, then we can create a
 597 // dynamic reloc and the dynamic linker will resolve it to the correct
 598 // address at runtime.  However, we do not want do that if the
 599 // relocation is in a read-only section, as it would prevent the
 600 // readonly segment from being shared.  And if we have to eventually
 601 // generate a COPY reloc, then any dynamic relocations will be
 602 // useless.  So this means that if this is a writable section, we need
 603 // to save the relocation until we see whether we have to create a
 604 // COPY relocation for this symbol for any other relocation.
 605
 606 void
 607 Target_x86_64::copy_reloc(const General_options* options,
 608                           Symbol_table* symtab,
 609                           Layout* layout,
 610                           Sized_relobj<64, false>* object,
 611                           unsigned int data_shndx,
 612                           Output_section* output_section,
 613                           Symbol* gsym,
 614                           const elfcpp::Rela<64, false>& rela)
 615 {
 616   Sized_symbol<64>* ssym;
 617   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(64) (gsym
 618                                                         SELECT_SIZE(64));
 619
 620   if (!Copy_relocs<64, false>::need_copy_reloc(options, object,
 621                                                data_shndx, ssym))
 622     {
 623       // So far we do not need a COPY reloc.  Save this relocation.
 624       // If it turns out that we never need a COPY reloc for this
 625       // symbol, then we will emit the relocation.
 626       if (this->copy_relocs_ == NULL)
 627         this->copy_relocs_ = new Copy_relocs<64, false>();
 628       this->copy_relocs_->save(ssym, object, data_shndx, output_section, rela);
 629     }
 630   else
 631     {
 632       // Allocate space for this symbol in the .bss section.
 633
 634       elfcpp::Elf_types<64>::Elf_WXword symsize = ssym->symsize();
 635
 636       // There is no defined way to determine the required alignment
 637       // of the symbol.  We pick the alignment based on the size.  We
 638       // set an arbitrary maximum of 256.
 639       unsigned int align;
 640       for (align = 1; align < 512; align <<= 1)
 641         if ((symsize & align) != 0)
 642           break;
 643
 644       if (this->dynbss_ == NULL)
 645         {
 646           this->dynbss_ = new Output_data_space(align);
 647           layout->add_output_section_data(".bss",
 648                                           elfcpp::SHT_NOBITS,
 649                                           (elfcpp::SHF_ALLOC
 650                                            | elfcpp::SHF_WRITE),
 651                                           this->dynbss_);
 652         }
 653
 654       Output_data_space* dynbss = this->dynbss_;
 655
 656       if (align > dynbss->addralign())
 657         dynbss->set_space_alignment(align);
 658
 659       off_t dynbss_size = dynbss->current_data_size();
 660       dynbss_size = align_address(dynbss_size, align);
 661       off_t offset = dynbss_size;
 662       dynbss->set_current_data_size(dynbss_size + symsize);
 663
 664       symtab->define_with_copy_reloc(this, ssym, dynbss, offset);
 665
 666       // Add the COPY reloc.
 667       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
 668       rela_dyn->add_global(ssym, elfcpp::R_X86_64_COPY, dynbss, offset, 0);
 669     }
 670 }
 671
 672
 673 // Optimize the TLS relocation type based on what we know about the
 674 // symbol.  IS_FINAL is true if the final address of this symbol is
 675 // known at link time.
 676
 677 tls::Tls_optimization
 678 Target_x86_64::optimize_tls_reloc(bool is_final, int r_type)
 679 {
 680   // If we are generating a shared library, then we can't do anything
 681   // in the linker.
 682   if (parameters->output_is_shared())
 683     return tls::TLSOPT_NONE;
 684
 685   switch (r_type)
 686     {
 687     case elfcpp::R_X86_64_TLSGD:
 688     case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 689     case elfcpp::R_X86_64_TLSDESC_CALL:
 690       // These are General-Dynamic which permits fully general TLS
 691       // access.  Since we know that we are generating an executable,
 692       // we can convert this to Initial-Exec.  If we also know that
 693       // this is a local symbol, we can further switch to Local-Exec.
 694       if (is_final)
 695         return tls::TLSOPT_TO_LE;
 696       return tls::TLSOPT_TO_IE;
 697
 698     case elfcpp::R_X86_64_TLSLD:
 699       // This is Local-Dynamic, which refers to a local symbol in the
 700       // dynamic TLS block.  Since we know that we generating an
 701       // executable, we can switch to Local-Exec.
 702       return tls::TLSOPT_TO_LE;
 703
 704     case elfcpp::R_X86_64_DTPOFF32:
 705     case elfcpp::R_X86_64_DTPOFF64:
 706       // Another Local-Dynamic reloc.
 707       return tls::TLSOPT_TO_LE;
 708
 709     case elfcpp::R_X86_64_GOTTPOFF:
 710       // These are Initial-Exec relocs which get the thread offset
 711       // from the GOT.  If we know that we are linking against the
 712       // local symbol, we can switch to Local-Exec, which links the
 713       // thread offset into the instruction.
 714       if (is_final)
 715         return tls::TLSOPT_TO_LE;
 716       return tls::TLSOPT_NONE;
 717
 718     case elfcpp::R_X86_64_TPOFF32:
 719       // When we already have Local-Exec, there is nothing further we
 720       // can do.
 721       return tls::TLSOPT_NONE;
 722
 723     default:
 724       gold_unreachable();
 725     }
 726 }
 727
 728 // Report an unsupported relocation against a local symbol.
 729
 730 void
 731 Target_x86_64::Scan::unsupported_reloc_local(Sized_relobj<64, false>* object,
 732                                              unsigned int r_type)
 733 {
 734   gold_error(_("%s: unsupported reloc %u against local symbol"),
 735              object->name().c_str(), r_type);
 736 }
 737
 738 // Scan a relocation for a local symbol.
 739
 740 inline void
 741 Target_x86_64::Scan::local(const General_options&,
 742                            Symbol_table* symtab,
 743                            Layout* layout,
 744                            Target_x86_64* target,
 745                            Sized_relobj<64, false>* object,
 746                            unsigned int data_shndx,
 747                            Output_section* output_section,
 748                            const elfcpp::Rela<64, false>& reloc,
 749                            unsigned int r_type,
 750                            const elfcpp::Sym<64, false>& lsym)
 751 {
 752   switch (r_type)
 753     {
 754     case elfcpp::R_X86_64_NONE:
 755     case elfcpp::R_386_GNU_VTINHERIT:
 756     case elfcpp::R_386_GNU_VTENTRY:
 757       break;
 758
 759     case elfcpp::R_X86_64_64:
 760       // If building a shared library (or a position-independent
 761       // executable), we need to create a dynamic relocation for
 762       // this location. The relocation applied at link time will
 763       // apply the link-time value, so we flag the location with
 764       // an R_386_RELATIVE relocation so the dynamic loader can
 765       // relocate it easily.
 766       if (parameters->output_is_position_independent())
 767         {
 768           unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 769           Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 770           rela_dyn->add_local_relative(object, r_sym,
 771                                        elfcpp::R_X86_64_RELATIVE,
 772                                        output_section, data_shndx,
 773                                        reloc.get_r_offset(),
 774                                        reloc.get_r_addend());
 775         }
 776       break;
 777
 778     case elfcpp::R_X86_64_32:
 779     case elfcpp::R_X86_64_32S:
 780     case elfcpp::R_X86_64_16:
 781     case elfcpp::R_X86_64_8:
 782       // If building a shared library (or a position-independent
 783       // executable), we need to create a dynamic relocation for
 784       // this location. The relocation applied at link time will
 785       // apply the link-time value, so we flag the location with
 786       // an R_386_RELATIVE relocation so the dynamic loader can
 787       // relocate it easily.
 788       if (parameters->output_is_position_independent())
 789         {
 790           Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 791           unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 792           rela_dyn->add_local(object, r_sym, r_type, output_section,
 793                               data_shndx, reloc.get_r_offset(),
 794                               reloc.get_r_addend());
 795         }
 796       break;
 797
 798     case elfcpp::R_X86_64_PC64:
 799     case elfcpp::R_X86_64_PC32:
 800     case elfcpp::R_X86_64_PC16:
 801     case elfcpp::R_X86_64_PC8:
 802       break;
 803
 804     case elfcpp::R_X86_64_PLT32:
 805       // Since we know this is a local symbol, we can handle this as a
 806       // PC32 reloc.
 807       break;
 808
 809     case elfcpp::R_X86_64_GOTPC32:
 810     case elfcpp::R_X86_64_GOTOFF64:
 811     case elfcpp::R_X86_64_GOTPC64:
 812     case elfcpp::R_X86_64_PLTOFF64:
 813       // We need a GOT section.
 814       target->got_section(symtab, layout);
 815       // For PLTOFF64, we'd normally want a PLT section, but since we
 816       // know this is a local symbol, no PLT is needed.
 817       break;
 818
 819     case elfcpp::R_X86_64_GOT64:
 820     case elfcpp::R_X86_64_GOT32:
 821     case elfcpp::R_X86_64_GOTPCREL64:
 822     case elfcpp::R_X86_64_GOTPCREL:
 823     case elfcpp::R_X86_64_GOTPLT64:
 824       {
 825         // The symbol requires a GOT entry.
 826         Output_data_got<64, false>* got = target->got_section(symtab, layout);
 827         unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 828         if (got->add_local(object, r_sym))
 829           {
 830             // If we are generating a shared object, we need to add a
 831             // dynamic relocation for this symbol's GOT entry.
 832             if (parameters->output_is_position_independent())
 833               {
 834                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 835                 // R_X86_64_RELATIVE assumes a 64-bit relocation.
 836                 if (r_type != elfcpp::R_X86_64_GOT32)
 837                   rela_dyn->add_local_relative(object, r_sym,
 838                                                elfcpp::R_X86_64_RELATIVE, got,
 839                                                object->local_got_offset(r_sym),
 840                                                0);
 841                 else
 842                   rela_dyn->add_local(object, r_sym, r_type,
 843                                       got, object->local_got_offset(r_sym), 0);
 844               }
 845           }
 846         // For GOTPLT64, we'd normally want a PLT section, but since
 847         // we know this is a local symbol, no PLT is needed.
 848       }
 849       break;
 850
 851     case elfcpp::R_X86_64_COPY:
 852     case elfcpp::R_X86_64_GLOB_DAT:
 853     case elfcpp::R_X86_64_JUMP_SLOT:
 854     case elfcpp::R_X86_64_RELATIVE:
 855       // These are outstanding tls relocs, which are unexpected when linking
 856     case elfcpp::R_X86_64_TPOFF64:
 857     case elfcpp::R_X86_64_DTPMOD64:
 858     case elfcpp::R_X86_64_TLSDESC:
 859       gold_error(_("%s: unexpected reloc %u in object file"),
 860                  object->name().c_str(), r_type);
 861       break;
 862
 863       // These are initial tls relocs, which are expected when linking
 864     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
 865     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
 866     case elfcpp::R_X86_64_TLSDESC_CALL:
 867     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
 868     case elfcpp::R_X86_64_DTPOFF32:
 869     case elfcpp::R_X86_64_DTPOFF64:
 870     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
 871     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
 872       {
 873         bool output_is_shared = parameters->output_is_shared();
 874         const tls::Tls_optimization optimized_type
 875             = Target_x86_64::optimize_tls_reloc(!output_is_shared, r_type);
 876         switch (r_type)
 877           {
 878           case elfcpp::R_X86_64_TLSGD:       // General-dynamic
 879             if (optimized_type == tls::TLSOPT_NONE)
 880               {
 881                 // Create a pair of GOT entries for the module index and
 882                 // dtv-relative offset.
 883                 Output_data_got<64, false>* got
 884                     = target->got_section(symtab, layout);
 885                 unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 886                 got->add_local_tls_with_rela(object, r_sym,
 887                                              lsym.get_st_shndx(), true,
 888                                              target->rela_dyn_section(layout),
 889                                              elfcpp::R_X86_64_DTPMOD64);
 890               }
 891             else if (optimized_type != tls::TLSOPT_TO_LE)
 892               unsupported_reloc_local(object, r_type);
 893             break;
 894
 895           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 896           case elfcpp::R_X86_64_TLSDESC_CALL:
 897             // FIXME: If not relaxing to LE, we need to generate
 898             // a GOT entry with a R_x86_64_TLSDESC reloc.
 899             if (optimized_type != tls::TLSOPT_TO_LE)
 900               unsupported_reloc_local(object, r_type);
 901             break;
 902
 903           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
 904             if (optimized_type == tls::TLSOPT_NONE)
 905               {
 906                 // Create a GOT entry for the module index.
 907                 Output_data_got<64, false>* got
 908                     = target->got_section(symtab, layout);
 909                 unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 910                 got->add_local_tls_with_rela(object, r_sym,
 911                                              lsym.get_st_shndx(), false,
 912                                              target->rela_dyn_section(layout),
 913                                              elfcpp::R_X86_64_DTPMOD64);
 914               }
 915             else if (optimized_type != tls::TLSOPT_TO_LE)
 916               unsupported_reloc_local(object, r_type);
 917             break;
 918
 919           case elfcpp::R_X86_64_DTPOFF32:
 920           case elfcpp::R_X86_64_DTPOFF64:
 921             break;
 922
 923           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
 924             if (optimized_type == tls::TLSOPT_NONE)
 925               {
 926                 // Create a GOT entry for the tp-relative offset.
 927                 Output_data_got<64, false>* got
 928                     = target->got_section(symtab, layout);
 929                 unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 930                 got->add_local_with_rela(object, r_sym,
 931                                          target->rela_dyn_section(layout),
 932                                          elfcpp::R_X86_64_TPOFF64);
 933               }
 934             else if (optimized_type != tls::TLSOPT_TO_LE)
 935               unsupported_reloc_local(object, r_type);
 936             break;
 937
 938           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
 939             if (output_is_shared)
 940               unsupported_reloc_local(object, r_type);
 941             break;
 942
 943           default:
 944             gold_unreachable();
 945           }
 946       }
 947       break;
 948
 949     case elfcpp::R_X86_64_SIZE32:
 950     case elfcpp::R_X86_64_SIZE64:
 951     default:
 952       gold_error(_("%s: unsupported reloc %u against local symbol"),
 953                  object->name().c_str(), r_type);
 954       break;
 955     }
 956 }
 957
 958
 959 // Report an unsupported relocation against a global symbol.
 960
 961 void
 962 Target_x86_64::Scan::unsupported_reloc_global(Sized_relobj<64, false>* object,
 963                                               unsigned int r_type,
 964                                               Symbol* gsym)
 965 {
 966   gold_error(_("%s: unsupported reloc %u against global symbol %s"),
 967              object->name().c_str(), r_type, gsym->demangled_name().c_str());
 968 }
 969
 970 // Scan a relocation for a global symbol.
 971
 972 inline void
 973 Target_x86_64::Scan::global(const General_options& options,
 974                             Symbol_table* symtab,
 975                             Layout* layout,
 976                             Target_x86_64* target,
 977                             Sized_relobj<64, false>* object,
 978                             unsigned int data_shndx,
 979                             Output_section* output_section,
 980                             const elfcpp::Rela<64, false>& reloc,
 981                             unsigned int r_type,
 982                             Symbol* gsym)
 983 {
 984   switch (r_type)
 985     {
 986     case elfcpp::R_X86_64_NONE:
 987     case elfcpp::R_386_GNU_VTINHERIT:
 988     case elfcpp::R_386_GNU_VTENTRY:
 989       break;
 990
 991     case elfcpp::R_X86_64_64:
 992     case elfcpp::R_X86_64_32:
 993     case elfcpp::R_X86_64_32S:
 994     case elfcpp::R_X86_64_16:
 995     case elfcpp::R_X86_64_8:
 996       {
 997         // Make a PLT entry if necessary.
 998         if (gsym->needs_plt_entry())
 999           {
1000             target->make_plt_entry(symtab, layout, gsym);
1001             // Since this is not a PC-relative relocation, we may be
1002             // taking the address of a function. In that case we need to
1003             // set the entry in the dynamic symbol table to the address of
1004             // the PLT entry.
1005             if (gsym->is_from_dynobj())
1006               gsym->set_needs_dynsym_value();
1007           }
1008         // Make a dynamic relocation if necessary.
1009         if (gsym->needs_dynamic_reloc(true, false))
1010           {
1011             if (target->may_need_copy_reloc(gsym))
1012               {
1013                 target->copy_reloc(&options, symtab, layout, object,
1014                                    data_shndx, output_section, gsym, reloc);
1015               }
1016             else if (r_type == elfcpp::R_X86_64_64
1017                      && gsym->can_use_relative_reloc(false))
1018               {
1019                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
1020                 rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_RELATIVE,
1021                                               output_section, object,
1022                                               data_shndx, reloc.get_r_offset(),
1023                                               reloc.get_r_addend());
1024               }
1025             else
1026               {
1027                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
1028                 rela_dyn->add_global(gsym, r_type, output_section, object,
1029                                      data_shndx, reloc.get_r_offset(),
1030                                      reloc.get_r_addend());
1031               }
1032           }
1033       }
1034       break;
1035
1036     case elfcpp::R_X86_64_PC64:
1037     case elfcpp::R_X86_64_PC32:
1038     case elfcpp::R_X86_64_PC16:
1039     case elfcpp::R_X86_64_PC8:
1040       {
1041         // Make a PLT entry if necessary.
1042         if (gsym->needs_plt_entry())
1043           target->make_plt_entry(symtab, layout, gsym);
1044         // Make a dynamic relocation if necessary.
1045         bool is_function_call = (gsym->type() == elfcpp::STT_FUNC);
1046         if (gsym->needs_dynamic_reloc(false, is_function_call))
1047           {
1048             if (target->may_need_copy_reloc(gsym))
1049               {
1050                 target->copy_reloc(&options, symtab, layout, object,
1051                                    data_shndx, output_section, gsym, reloc);
1052               }
1053             else
1054               {
1055                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
1056                 rela_dyn->add_global(gsym, r_type, output_section, object,
1057                                      data_shndx, reloc.get_r_offset(),
1058                                      reloc.get_r_addend());
1059               }
1060           }
1061       }
1062       break;
1063
1064     case elfcpp::R_X86_64_GOT64:
1065     case elfcpp::R_X86_64_GOT32:
1066     case elfcpp::R_X86_64_GOTPCREL64:
1067     case elfcpp::R_X86_64_GOTPCREL:
1068     case elfcpp::R_X86_64_GOTPLT64:
1069       {
1070         // The symbol requires a GOT entry.
1071         Output_data_got<64, false>* got = target->got_section(symtab, layout);
1072         if (gsym->final_value_is_known())
1073           got->add_global(gsym);
1074         else
1075           {
1076             // If this symbol is not fully resolved, we need to add a
1077             // dynamic relocation for it.
1078             Reloc_section* rela_dyn = target->rela_dyn_section(layout);
1079             if (gsym->is_from_dynobj() || gsym->is_preemptible())
1080               got->add_global_with_rela(gsym, rela_dyn,
1081                                         elfcpp::R_X86_64_GLOB_DAT);
1082             else
1083               {
1084                 if (got->add_global(gsym))
1085                   rela_dyn->add_global_relative(gsym,
1086                                                 elfcpp::R_X86_64_RELATIVE,
1087                                                 got, gsym->got_offset(), 0);
1088               }
1089           }
1090         // For GOTPLT64, we also need a PLT entry (but only if the
1091         // symbol is not fully resolved).
1092         if (r_type == elfcpp::R_X86_64_GOTPLT64
1093             && !gsym->final_value_is_known())
1094           target->make_plt_entry(symtab, layout, gsym);
1095       }
1096       break;
1097
1098     case elfcpp::R_X86_64_PLT32:
1099       // If the symbol is fully resolved, this is just a PC32 reloc.
1100       // Otherwise we need a PLT entry.
1101       if (gsym->final_value_is_known())
1102         break;
1103       // If building a shared library, we can also skip the PLT entry
1104       // if the symbol is defined in the output file and is protected
1105       // or hidden.
1106       if (gsym->is_defined()
1107           && !gsym->is_from_dynobj()
1108           && !gsym->is_preemptible())
1109         break;
1110       target->make_plt_entry(symtab, layout, gsym);
1111       break;
1112
1113     case elfcpp::R_X86_64_GOTPC32:
1114     case elfcpp::R_X86_64_GOTOFF64:
1115     case elfcpp::R_X86_64_GOTPC64:
1116     case elfcpp::R_X86_64_PLTOFF64:
1117       // We need a GOT section.
1118       target->got_section(symtab, layout);
1119       // For PLTOFF64, we also need a PLT entry (but only if the
1120       // symbol is not fully resolved).
1121       if (r_type == elfcpp::R_X86_64_PLTOFF64
1122           && !gsym->final_value_is_known())
1123         target->make_plt_entry(symtab, layout, gsym);
1124       break;
1125
1126     case elfcpp::R_X86_64_COPY:
1127     case elfcpp::R_X86_64_GLOB_DAT:
1128     case elfcpp::R_X86_64_JUMP_SLOT:
1129     case elfcpp::R_X86_64_RELATIVE:
1130       // These are outstanding tls relocs, which are unexpected when linking
1131     case elfcpp::R_X86_64_TPOFF64:
1132     case elfcpp::R_X86_64_DTPMOD64:
1133     case elfcpp::R_X86_64_TLSDESC:
1134       gold_error(_("%s: unexpected reloc %u in object file"),
1135                  object->name().c_str(), r_type);
1136       break;
1137
1138       // These are initial tls relocs, which are expected for global()
1139     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1140     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1141     case elfcpp::R_X86_64_TLSDESC_CALL:
1142     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1143     case elfcpp::R_X86_64_DTPOFF32:
1144     case elfcpp::R_X86_64_DTPOFF64:
1145     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1146     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1147       {
1148         const bool is_final = gsym->final_value_is_known();
1149         const tls::Tls_optimization optimized_type
1150             = Target_x86_64::optimize_tls_reloc(is_final, r_type);
1151         switch (r_type)
1152           {
1153           case elfcpp::R_X86_64_TLSGD:       // General-dynamic
1154             if (optimized_type == tls::TLSOPT_NONE)
1155               {
1156                 // Create a pair of GOT entries for the module index and
1157                 // dtv-relative offset.
1158                 Output_data_got<64, false>* got
1159                     = target->got_section(symtab, layout);
1160                 got->add_global_tls_with_rela(gsym,
1161                                               target->rela_dyn_section(layout),
1162                                               elfcpp::R_X86_64_DTPMOD64,
1163                                               elfcpp::R_X86_64_DTPOFF64);
1164               }
1165             else if (optimized_type == tls::TLSOPT_TO_IE)
1166               {
1167                 // Create a GOT entry for the tp-relative offset.
1168                 Output_data_got<64, false>* got
1169                     = target->got_section(symtab, layout);
1170                 got->add_global_with_rela(gsym,
1171                                           target->rela_dyn_section(layout),
1172                                           elfcpp::R_X86_64_TPOFF64);
1173               }
1174             else if (optimized_type != tls::TLSOPT_TO_LE)
1175               unsupported_reloc_global(object, r_type, gsym);
1176             break;
1177
1178           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
1179           case elfcpp::R_X86_64_TLSDESC_CALL:
1180             // FIXME: If not relaxing to LE, we need to generate
1181             // DTPMOD64 and DTPOFF64, or TLSDESC, relocs.
1182             if (optimized_type != tls::TLSOPT_TO_LE)
1183               unsupported_reloc_global(object, r_type, gsym);
1184             break;
1185
1186           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
1187             if (optimized_type == tls::TLSOPT_NONE)
1188               {
1189                 // Create a GOT entry for the module index.
1190                 Output_data_got<64, false>* got
1191                     = target->got_section(symtab, layout);
1192                 got->add_global_tls_with_rela(gsym,
1193                                               target->rela_dyn_section(layout),
1194                                               elfcpp::R_X86_64_DTPMOD64);
1195               }
1196             else if (optimized_type != tls::TLSOPT_TO_LE)
1197               unsupported_reloc_global(object, r_type, gsym);
1198             break;
1199
1200           case elfcpp::R_X86_64_DTPOFF32:
1201           case elfcpp::R_X86_64_DTPOFF64:
1202             break;
1203
1204           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
1205             if (optimized_type == tls::TLSOPT_NONE)
1206               {
1207                 // Create a GOT entry for the tp-relative offset.
1208                 Output_data_got<64, false>* got
1209                     = target->got_section(symtab, layout);
1210                 got->add_global_with_rela(gsym,
1211                                           target->rela_dyn_section(layout),
1212                                           elfcpp::R_X86_64_TPOFF64);
1213               }
1214             else if (optimized_type != tls::TLSOPT_TO_LE)
1215               unsupported_reloc_global(object, r_type, gsym);
1216             break;
1217
1218           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
1219             if (parameters->output_is_shared())
1220               unsupported_reloc_local(object, r_type);
1221             break;
1222
1223           default:
1224             gold_unreachable();
1225           }
1226       }
1227       break;
1228
1229     case elfcpp::R_X86_64_SIZE32:
1230     case elfcpp::R_X86_64_SIZE64:
1231     default:
1232       gold_error(_("%s: unsupported reloc %u against global symbol %s"),
1233                  object->name().c_str(), r_type,
1234                  gsym->demangled_name().c_str());
1235       break;
1236     }
1237 }
1238
1239 // Scan relocations for a section.
1240
1241 void
1242 Target_x86_64::scan_relocs(const General_options& options,
1243                            Symbol_table* symtab,
1244                            Layout* layout,
1245                            Sized_relobj<64, false>* object,
1246                            unsigned int data_shndx,
1247                            unsigned int sh_type,
1248                            const unsigned char* prelocs,
1249                            size_t reloc_count,
1250                            Output_section* output_section,
1251                            bool needs_special_offset_handling,
1252                            size_t local_symbol_count,
1253                            const unsigned char* plocal_symbols)
1254 {
1255   if (sh_type == elfcpp::SHT_REL)
1256     {
1257       gold_error(_("%s: unsupported REL reloc section"),
1258                  object->name().c_str());
1259       return;
1260     }
1261
1262   gold::scan_relocs<64, false, Target_x86_64, elfcpp::SHT_RELA,
1263       Target_x86_64::Scan>(
1264     options,
1265     symtab,
1266     layout,
1267     this,
1268     object,
1269     data_shndx,
1270     prelocs,
1271     reloc_count,
1272     output_section,
1273     needs_special_offset_handling,
1274     local_symbol_count,
1275     plocal_symbols);
1276 }
1277
1278 // Finalize the sections.
1279
1280 void
1281 Target_x86_64::do_finalize_sections(Layout* layout)
1282 {
1283   // Fill in some more dynamic tags.
1284   Output_data_dynamic* const odyn = layout->dynamic_data();
1285   if (odyn != NULL)
1286     {
1287       if (this->got_plt_ != NULL)
1288         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1289
1290       if (this->plt_ != NULL)
1291         {
1292           const Output_data* od = this->plt_->rel_plt();
1293           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1294           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1295           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_RELA);
1296         }
1297
1298       if (this->rela_dyn_ != NULL)
1299         {
1300           const Output_data* od = this->rela_dyn_;
1301           odyn->add_section_address(elfcpp::DT_RELA, od);
1302           odyn->add_section_size(elfcpp::DT_RELASZ, od);
1303           odyn->add_constant(elfcpp::DT_RELAENT,
1304                              elfcpp::Elf_sizes<64>::rela_size);
1305         }
1306
1307       if (!parameters->output_is_shared())
1308         {
1309           // The value of the DT_DEBUG tag is filled in by the dynamic
1310           // linker at run time, and used by the debugger.
1311           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1312         }
1313     }
1314
1315   // Emit any relocs we saved in an attempt to avoid generating COPY
1316   // relocs.
1317   if (this->copy_relocs_ == NULL)
1318     return;
1319   if (this->copy_relocs_->any_to_emit())
1320     {
1321       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
1322       this->copy_relocs_->emit(rela_dyn);
1323     }
1324   delete this->copy_relocs_;
1325   this->copy_relocs_ = NULL;
1326 }
1327
1328 // Perform a relocation.
1329
1330 inline bool
1331 Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo,
1332                                   Target_x86_64* target,
1333                                   size_t relnum,
1334                                   const elfcpp::Rela<64, false>& rela,
1335                                   unsigned int r_type,
1336                                   const Sized_symbol<64>* gsym,
1337                                   const Symbol_value<64>* psymval,
1338                                   unsigned char* view,
1339                                   elfcpp::Elf_types<64>::Elf_Addr address,
1340                                   off_t view_size)
1341 {
1342   if (this->skip_call_tls_get_addr_)
1343     {
1344       if (r_type != elfcpp::R_X86_64_PLT32
1345           || gsym == NULL
1346           || strcmp(gsym->name(), "__tls_get_addr") != 0)
1347         {
1348           gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1349                                  _("missing expected TLS relocation"));
1350         }
1351       else
1352         {
1353           this->skip_call_tls_get_addr_ = false;
1354           return false;
1355         }
1356     }
1357
1358   // Pick the value to use for symbols defined in shared objects.
1359   Symbol_value<64> symval;
1360   if (gsym != NULL
1361       && (gsym->is_from_dynobj()
1362           || (parameters->output_is_shared()
1363               && gsym->is_preemptible()))
1364       && gsym->has_plt_offset())
1365     {
1366       symval.set_output_value(target->plt_section()->address()
1367                               + gsym->plt_offset());
1368       psymval = &symval;
1369     }
1370
1371   const Sized_relobj<64, false>* object = relinfo->object;
1372   const elfcpp::Elf_Xword addend = rela.get_r_addend();
1373
1374   // Get the GOT offset if needed.
1375   // The GOT pointer points to the end of the GOT section.
1376   // We need to subtract the size of the GOT section to get
1377   // the actual offset to use in the relocation.
1378   bool have_got_offset = false;
1379   unsigned int got_offset = 0;
1380   switch (r_type)
1381     {
1382     case elfcpp::R_X86_64_GOT32:
1383     case elfcpp::R_X86_64_GOT64:
1384     case elfcpp::R_X86_64_GOTPLT64:
1385     case elfcpp::R_X86_64_GOTPCREL:
1386     case elfcpp::R_X86_64_GOTPCREL64:
1387       if (gsym != NULL)
1388         {
1389           gold_assert(gsym->has_got_offset());
1390           got_offset = gsym->got_offset() - target->got_size();
1391         }
1392       else
1393         {
1394           unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1395           gold_assert(object->local_has_got_offset(r_sym));
1396           got_offset = object->local_got_offset(r_sym) - target->got_size();
1397         }
1398       have_got_offset = true;
1399       break;
1400
1401     default:
1402       break;
1403     }
1404
1405   switch (r_type)
1406     {
1407     case elfcpp::R_X86_64_NONE:
1408     case elfcpp::R_386_GNU_VTINHERIT:
1409     case elfcpp::R_386_GNU_VTENTRY:
1410       break;
1411
1412     case elfcpp::R_X86_64_64:
1413       Relocate_functions<64, false>::rela64(view, object, psymval, addend);
1414       break;
1415
1416     case elfcpp::R_X86_64_PC64:
1417       Relocate_functions<64, false>::pcrela64(view, object, psymval, addend,
1418                                               address);
1419       break;
1420
1421     case elfcpp::R_X86_64_32:
1422       // FIXME: we need to verify that value + addend fits into 32 bits:
1423       //    uint64_t x = value + addend;
1424       //    x == static_cast<uint64_t>(static_cast<uint32_t>(x))
1425       // Likewise for other <=32-bit relocations (but see R_X86_64_32S).
1426       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1427       break;
1428
1429     case elfcpp::R_X86_64_32S:
1430       // FIXME: we need to verify that value + addend fits into 32 bits:
1431       //    int64_t x = value + addend;   // note this quantity is signed!
1432       //    x == static_cast<int64_t>(static_cast<int32_t>(x))
1433       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1434       break;
1435
1436     case elfcpp::R_X86_64_PC32:
1437       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1438                                               address);
1439       break;
1440
1441     case elfcpp::R_X86_64_16:
1442       Relocate_functions<64, false>::rela16(view, object, psymval, addend);
1443       break;
1444
1445     case elfcpp::R_X86_64_PC16:
1446       Relocate_functions<64, false>::pcrela16(view, object, psymval, addend,
1447                                               address);
1448       break;
1449
1450     case elfcpp::R_X86_64_8:
1451       Relocate_functions<64, false>::rela8(view, object, psymval, addend);
1452       break;
1453
1454     case elfcpp::R_X86_64_PC8:
1455       Relocate_functions<64, false>::pcrela8(view, object, psymval, addend,
1456                                              address);
1457       break;
1458
1459     case elfcpp::R_X86_64_PLT32:
1460       gold_assert(gsym == NULL
1461                   || gsym->has_plt_offset()
1462                   || gsym->final_value_is_known());
1463       // Note: while this code looks the same as for R_X86_64_PC32, it
1464       // behaves differently because psymval was set to point to
1465       // the PLT entry, rather than the symbol, in Scan::global().
1466       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1467                                               address);
1468       break;
1469
1470     case elfcpp::R_X86_64_PLTOFF64:
1471       {
1472         gold_assert(gsym);
1473         gold_assert(gsym->has_plt_offset()
1474                     || gsym->final_value_is_known());
1475         elfcpp::Elf_types<64>::Elf_Addr got_address;
1476         got_address = target->got_section(NULL, NULL)->address();
1477         Relocate_functions<64, false>::rela64(view, object, psymval,
1478                                               addend - got_address);
1479       }
1480
1481     case elfcpp::R_X86_64_GOT32:
1482       gold_assert(have_got_offset);
1483       Relocate_functions<64, false>::rela32(view, got_offset, addend);
1484       break;
1485
1486     case elfcpp::R_X86_64_GOTPC32:
1487       {
1488         gold_assert(gsym);
1489         elfcpp::Elf_types<64>::Elf_Addr value;
1490         value = target->got_plt_section()->address();
1491         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1492       }
1493       break;
1494
1495     case elfcpp::R_X86_64_GOT64:
1496       // The ABI doc says "Like GOT64, but indicates a PLT entry is needed."
1497       // Since we always add a PLT entry, this is equivalent.
1498     case elfcpp::R_X86_64_GOTPLT64:
1499       gold_assert(have_got_offset);
1500       Relocate_functions<64, false>::rela64(view, got_offset, addend);
1501       break;
1502
1503     case elfcpp::R_X86_64_GOTPC64:
1504       {
1505         gold_assert(gsym);
1506         elfcpp::Elf_types<64>::Elf_Addr value;
1507         value = target->got_plt_section()->address();
1508         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1509       }
1510       break;
1511
1512     case elfcpp::R_X86_64_GOTOFF64:
1513       {
1514         elfcpp::Elf_types<64>::Elf_Addr value;
1515         value = (psymval->value(object, 0)
1516                  - target->got_plt_section()->address());
1517         Relocate_functions<64, false>::rela64(view, value, addend);
1518       }
1519       break;
1520
1521     case elfcpp::R_X86_64_GOTPCREL:
1522       {
1523         gold_assert(have_got_offset);
1524         elfcpp::Elf_types<64>::Elf_Addr value;
1525         value = target->got_plt_section()->address() + got_offset;
1526         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1527       }
1528       break;
1529
1530     case elfcpp::R_X86_64_GOTPCREL64:
1531       {
1532         gold_assert(have_got_offset);
1533         elfcpp::Elf_types<64>::Elf_Addr value;
1534         value = target->got_plt_section()->address() + got_offset;
1535         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1536       }
1537       break;
1538
1539     case elfcpp::R_X86_64_COPY:
1540     case elfcpp::R_X86_64_GLOB_DAT:
1541     case elfcpp::R_X86_64_JUMP_SLOT:
1542     case elfcpp::R_X86_64_RELATIVE:
1543       // These are outstanding tls relocs, which are unexpected when linking
1544     case elfcpp::R_X86_64_TPOFF64:
1545     case elfcpp::R_X86_64_DTPMOD64:
1546     case elfcpp::R_X86_64_TLSDESC:
1547       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1548                              _("unexpected reloc %u in object file"),
1549                              r_type);
1550       break;
1551
1552       // These are initial tls relocs, which are expected when linking
1553     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1554     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1555     case elfcpp::R_X86_64_TLSDESC_CALL:
1556     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1557     case elfcpp::R_X86_64_DTPOFF32:
1558     case elfcpp::R_X86_64_DTPOFF64:
1559     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1560     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1561       this->relocate_tls(relinfo, target, relnum, rela, r_type, gsym, psymval,
1562                          view, address, view_size);
1563       break;
1564
1565     case elfcpp::R_X86_64_SIZE32:
1566     case elfcpp::R_X86_64_SIZE64:
1567     default:
1568       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1569                              _("unsupported reloc %u"),
1570                              r_type);
1571       break;
1572     }
1573
1574   return true;
1575 }
1576
1577 // Perform a TLS relocation.
1578
1579 inline void
1580 Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo,
1581                                       Target_x86_64* target,
1582                                       size_t relnum,
1583                                       const elfcpp::Rela<64, false>& rela,
1584                                       unsigned int r_type,
1585                                       const Sized_symbol<64>* gsym,
1586                                       const Symbol_value<64>* psymval,
1587                                       unsigned char* view,
1588                                       elfcpp::Elf_types<64>::Elf_Addr,
1589                                       off_t view_size)
1590 {
1591   Output_segment* tls_segment = relinfo->layout->tls_segment();
1592
1593   const Sized_relobj<64, false>* object = relinfo->object;
1594
1595   elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0);
1596
1597   const bool is_final = (gsym == NULL
1598                          ? !parameters->output_is_position_independent()
1599                          : gsym->final_value_is_known());
1600   const tls::Tls_optimization optimized_type
1601       = Target_x86_64::optimize_tls_reloc(is_final, r_type);
1602   switch (r_type)
1603     {
1604     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1605     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1606     case elfcpp::R_X86_64_TLSDESC_CALL:
1607       if (optimized_type == tls::TLSOPT_TO_LE)
1608         {
1609           gold_assert(tls_segment != NULL);
1610           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1611                              rela, r_type, value, view,
1612                              view_size);
1613           break;
1614         }
1615       else
1616         {
1617           unsigned int got_offset;
1618           if (gsym != NULL)
1619             {
1620               gold_assert(gsym->has_tls_got_offset(true));
1621               got_offset = gsym->tls_got_offset(true) - target->got_size();
1622             }
1623           else
1624             {
1625               unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1626               gold_assert(object->local_has_tls_got_offset(r_sym, true));
1627               got_offset = (object->local_tls_got_offset(r_sym, true)
1628                             - target->got_size());
1629             }
1630           if (optimized_type == tls::TLSOPT_TO_IE)
1631             {
1632               gold_assert(tls_segment != NULL);
1633               this->tls_gd_to_ie(relinfo, relnum, tls_segment, rela, r_type,
1634                                  got_offset, view, view_size);
1635               break;
1636             }
1637           else if (optimized_type == tls::TLSOPT_NONE)
1638             {
1639               // Relocate the field with the offset of the pair of GOT
1640               // entries.
1641               Relocate_functions<64, false>::rel64(view, got_offset);
1642               break;
1643             }
1644         }
1645       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1646                              _("unsupported reloc %u"), r_type);
1647       break;
1648
1649     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1650       if (optimized_type == tls::TLSOPT_TO_LE)
1651         {
1652           gold_assert(tls_segment != NULL);
1653           this->tls_ld_to_le(relinfo, relnum, tls_segment, rela, r_type,
1654                              value, view, view_size);
1655           break;
1656         }
1657       else if (optimized_type == tls::TLSOPT_NONE)
1658         {
1659           // Relocate the field with the offset of the GOT entry for
1660           // the module index.
1661           unsigned int got_offset;
1662           if (gsym != NULL)
1663             {
1664               gold_assert(gsym->has_tls_got_offset(false));
1665               got_offset = gsym->tls_got_offset(false) - target->got_size();
1666             }
1667           else
1668             {
1669               unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1670               gold_assert(object->local_has_tls_got_offset(r_sym, false));
1671               got_offset = (object->local_tls_got_offset(r_sym, false)
1672                             - target->got_size());
1673             }
1674           Relocate_functions<64, false>::rel64(view, got_offset);
1675           break;
1676         }
1677       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1678                              _("unsupported reloc %u"), r_type);
1679       break;
1680
1681     case elfcpp::R_X86_64_DTPOFF32:
1682       gold_assert(tls_segment != NULL);
1683       if (optimized_type == tls::TLSOPT_TO_LE)
1684         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1685       else
1686         value = value - tls_segment->vaddr();
1687       Relocate_functions<64, false>::rel32(view, value);
1688       break;
1689
1690     case elfcpp::R_X86_64_DTPOFF64:
1691       gold_assert(tls_segment != NULL);
1692       if (optimized_type == tls::TLSOPT_TO_LE)
1693         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1694       else
1695         value = value - tls_segment->vaddr();
1696       Relocate_functions<64, false>::rel64(view, value);
1697       break;
1698
1699     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1700       if (optimized_type == tls::TLSOPT_TO_LE)
1701         {
1702           gold_assert(tls_segment != NULL);
1703           Target_x86_64::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1704                                                 rela, r_type, value, view,
1705                                                 view_size);
1706           break;
1707         }
1708       else if (optimized_type == tls::TLSOPT_NONE)
1709         {
1710           // Relocate the field with the offset of the GOT entry for
1711           // the tp-relative offset of the symbol.
1712           unsigned int got_offset;
1713           if (gsym != NULL)
1714             {
1715               gold_assert(gsym->has_got_offset());
1716               got_offset = gsym->got_offset() - target->got_size();
1717             }
1718           else
1719             {
1720               unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1721               gold_assert(object->local_has_got_offset(r_sym));
1722               got_offset = (object->local_got_offset(r_sym)
1723                             - target->got_size());
1724             }
1725           Relocate_functions<64, false>::rel64(view, got_offset);
1726           break;
1727         }
1728       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1729                              _("unsupported reloc type %u"),
1730                              r_type);
1731       break;
1732
1733     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1734       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1735       Relocate_functions<64, false>::rel32(view, value);
1736       break;
1737     }
1738 }
1739
1740 // Do a relocation in which we convert a TLS General-Dynamic to an
1741 // Initial-Exec.
1742
1743 inline void
1744 Target_x86_64::Relocate::tls_gd_to_ie(const Relocate_info<64, false>* relinfo,
1745                                       size_t relnum,
1746                                       Output_segment* tls_segment,
1747                                       const elfcpp::Rela<64, false>& rela,
1748                                       unsigned int,
1749                                       elfcpp::Elf_types<64>::Elf_Addr value,
1750                                       unsigned char* view,
1751                                       off_t view_size)
1752 {
1753   // .byte 0x66; leaq foo@tlsgd(%rip),%rdi;
1754   // .word 0x6666; rex64; call __tls_get_addr
1755   // ==> movq %fs:0,%rax; addq x@gottpoff(%rip),%rax
1756
1757   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4);
1758   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12);
1759
1760   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1761                  (memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0));
1762   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1763                  (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0));
1764
1765   memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x03\x05\0\0\0\0", 16);
1766
1767   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1768   Relocate_functions<64, false>::rela32(view + 8, value, 0);
1769
1770   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1771   // We can skip it.
1772   this->skip_call_tls_get_addr_ = true;
1773 }
1774
1775 // Do a relocation in which we convert a TLS General-Dynamic to a
1776 // Local-Exec.
1777
1778 inline void
1779 Target_x86_64::Relocate::tls_gd_to_le(const Relocate_info<64, false>* relinfo,
1780                                       size_t relnum,
1781                                       Output_segment* tls_segment,
1782                                       const elfcpp::Rela<64, false>& rela,
1783                                       unsigned int,
1784                                       elfcpp::Elf_types<64>::Elf_Addr value,
1785                                       unsigned char* view,
1786                                       off_t view_size)
1787 {
1788   // .byte 0x66; leaq foo@tlsgd(%rip),%rdi;
1789   // .word 0x6666; rex64; call __tls_get_addr
1790   // ==> movq %fs:0,%rax; leaq x@tpoff(%rax),%rax
1791
1792   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4);
1793   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12);
1794
1795   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1796                  (memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0));
1797   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1798                  (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0));
1799
1800   memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x8d\x80\0\0\0\0", 16);
1801
1802   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1803   Relocate_functions<64, false>::rela32(view + 8, value, 0);
1804
1805   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1806   // We can skip it.
1807   this->skip_call_tls_get_addr_ = true;
1808 }
1809
1810 inline void
1811 Target_x86_64::Relocate::tls_ld_to_le(const Relocate_info<64, false>* relinfo,
1812                                       size_t relnum,
1813                                       Output_segment*,
1814                                       const elfcpp::Rela<64, false>& rela,
1815                                       unsigned int,
1816                                       elfcpp::Elf_types<64>::Elf_Addr,
1817                                       unsigned char* view,
1818                                       off_t view_size)
1819 {
1820   // leaq foo@tlsld(%rip),%rdi; call __tls_get_addr@plt;
1821   // ... leq foo@dtpoff(%rax),%reg
1822   // ==> .word 0x6666; .byte 0x66; movq %fs:0,%rax ... leaq x@tpoff(%rax),%rdx
1823
1824   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1825   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 9);
1826
1827   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1828                  view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x3d);
1829
1830   tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[4] == 0xe8);
1831
1832   memcpy(view - 3, "\x66\x66\x66\x64\x48\x8b\x04\x25\0\0\0\0", 12);
1833
1834   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1835   // We can skip it.
1836   this->skip_call_tls_get_addr_ = true;
1837 }
1838
1839 // Do a relocation in which we convert a TLS Initial-Exec to a
1840 // Local-Exec.
1841
1842 inline void
1843 Target_x86_64::Relocate::tls_ie_to_le(const Relocate_info<64, false>* relinfo,
1844                                       size_t relnum,
1845                                       Output_segment* tls_segment,
1846                                       const elfcpp::Rela<64, false>& rela,
1847                                       unsigned int,
1848                                       elfcpp::Elf_types<64>::Elf_Addr value,
1849                                       unsigned char* view,
1850                                       off_t view_size)
1851 {
1852   // We need to examine the opcodes to figure out which instruction we
1853   // are looking at.
1854
1855   // movq foo@gottpoff(%rip),%reg  ==>  movq $YY,%reg
1856   // addq foo@gottpoff(%rip),%reg  ==>  addq $YY,%reg
1857
1858   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1859   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 4);
1860
1861   unsigned char op1 = view[-3];
1862   unsigned char op2 = view[-2];
1863   unsigned char op3 = view[-1];
1864   unsigned char reg = op3 >> 3;
1865
1866   if (op2 == 0x8b)
1867     {
1868       // movq
1869       if (op1 == 0x4c)
1870         view[-3] = 0x49;
1871       view[-2] = 0xc7;
1872       view[-1] = 0xc0 | reg;
1873     }
1874   else if (reg == 4)
1875     {
1876       // Special handling for %rsp.
1877       if (op1 == 0x4c)
1878         view[-3] = 0x49;
1879       view[-2] = 0x81;
1880       view[-1] = 0xc0 | reg;
1881     }
1882   else
1883     {
1884       // addq
1885       if (op1 == 0x4c)
1886         view[-3] = 0x4d;
1887       view[-2] = 0x8d;
1888       view[-1] = 0x80 | reg | (reg << 3);
1889     }
1890
1891   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1892   Relocate_functions<64, false>::rela32(view, value, 0);
1893 }
1894
1895 // Relocate section data.
1896
1897 void
1898 Target_x86_64::relocate_section(const Relocate_info<64, false>* relinfo,
1899                                 unsigned int sh_type,
1900                                 const unsigned char* prelocs,
1901                                 size_t reloc_count,
1902                                 Output_section* output_section,
1903                                 bool needs_special_offset_handling,
1904                                 unsigned char* view,
1905                                 elfcpp::Elf_types<64>::Elf_Addr address,
1906                                 off_t view_size)
1907 {
1908   gold_assert(sh_type == elfcpp::SHT_RELA);
1909
1910   gold::relocate_section<64, false, Target_x86_64, elfcpp::SHT_RELA,
1911                          Target_x86_64::Relocate>(
1912     relinfo,
1913     this,
1914     prelocs,
1915     reloc_count,
1916     output_section,
1917     needs_special_offset_handling,
1918     view,
1919     address,
1920     view_size);
1921 }
1922
1923 // Return the value to use for a dynamic which requires special
1924 // treatment.  This is how we support equality comparisons of function
1925 // pointers across shared library boundaries, as described in the
1926 // processor specific ABI supplement.
1927
1928 uint64_t
1929 Target_x86_64::do_dynsym_value(const Symbol* gsym) const
1930 {
1931   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1932   return this->plt_section()->address() + gsym->plt_offset();
1933 }
1934
1935 // Return a string used to fill a code section with nops to take up
1936 // the specified length.
1937
1938 std::string
1939 Target_x86_64::do_code_fill(off_t length)
1940 {
1941   if (length >= 16)
1942     {
1943       // Build a jmpq instruction to skip over the bytes.
1944       unsigned char jmp[5];
1945       jmp[0] = 0xe9;
1946       elfcpp::Swap_unaligned<64, false>::writeval(jmp + 1, length - 5);
1947       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1948               + std::string(length - 5, '\0'));
1949     }
1950
1951   // Nop sequences of various lengths.
1952   const char nop1[1] = { 0x90 };                   // nop
1953   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1954   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1955   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1956   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1957                          0x00 };                   // leal 0(%esi,1),%esi
1958   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1959                          0x00, 0x00 };
1960   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1961                          0x00, 0x00, 0x00 };
1962   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1963                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1964   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1965                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1966                          0x00 };
1967   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1968                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1969                            0x00, 0x00 };
1970   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1971                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1972                            0x00, 0x00, 0x00 };
1973   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1974                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1975                            0x00, 0x00, 0x00, 0x00 };
1976   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1977                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1978                            0x27, 0x00, 0x00, 0x00,
1979                            0x00 };
1980   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1981                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1982                            0xbc, 0x27, 0x00, 0x00,
1983                            0x00, 0x00 };
1984   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1985                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1986                            0x90, 0x90, 0x90, 0x90,
1987                            0x90, 0x90, 0x90 };
1988
1989   const char* nops[16] = {
1990     NULL,
1991     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1992     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1993   };
1994
1995   return std::string(nops[length], length);
1996 }
1997
1998 // The selector for x86_64 object files.
1999
2000 class Target_selector_x86_64 : public Target_selector
2001 {
2002 public:
2003   Target_selector_x86_64()
2004     : Target_selector(elfcpp::EM_X86_64, 64, false)
2005   { }
2006
2007   Target*
2008   recognize(int machine, int osabi, int abiversion);
2009
2010  private:
2011   Target_x86_64* target_;
2012 };
2013
2014 // Recognize an x86_64 object file when we already know that the machine
2015 // number is EM_X86_64.
2016
2017 Target*
2018 Target_selector_x86_64::recognize(int, int, int)
2019 {
2020   if (this->target_ == NULL)
2021     this->target_ = new Target_x86_64();
2022   return this->target_;
2023 }
2024
2025 Target_selector_x86_64 target_selector_x86_64;
2026
2027 } // End anonymous namespace.