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 + 4
 482   0xff, 0x25,   // jmp indirect
 483   0, 0, 0, 0,   // replaced with address of .got + 8
 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   if (!parameters->output_is_shared())
 522     {
 523       // We do a jmp relative to the PC at the end of this instruction.
 524       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 8
 525                                                   - (plt_address + 6));
 526       elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 16
 527                                         - (plt_address + 12));
 528     }
 529   pov += plt_entry_size;
 530
 531   unsigned char* got_pov = got_view;
 532
 533   memset(got_pov, 0, 24);
 534   got_pov += 24;
 535
 536   unsigned int plt_offset = plt_entry_size;
 537   unsigned int got_offset = 24;
 538   const unsigned int count = this->count_;
 539   for (unsigned int plt_index = 0;
 540        plt_index < count;
 541        ++plt_index,
 542          pov += plt_entry_size,
 543          got_pov += 8,
 544          plt_offset += plt_entry_size,
 545          got_offset += 8)
 546     {
 547       // Set and adjust the PLT entry itself.
 548       memcpy(pov, plt_entry, plt_entry_size);
 549       if (parameters->output_is_shared())
 550         // FIXME(csilvers): what's the right thing to write here?
 551         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
 552       else
 553         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 554                                                     (got_address + got_offset
 555                                                      - (plt_address + plt_offset
 556                                                         + 6)));
 557
 558       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_index);
 559       elfcpp::Swap<32, false>::writeval(pov + 12,
 560                                         - (plt_offset + plt_entry_size));
 561
 562       // Set the entry in the GOT.
 563       elfcpp::Swap<64, false>::writeval(got_pov, plt_address + plt_offset + 6);
 564     }
 565
 566   gold_assert(pov - oview == oview_size);
 567   gold_assert(got_pov - got_view == got_size);
 568
 569   of->write_output_view(offset, oview_size, oview);
 570   of->write_output_view(got_file_offset, got_size, got_view);
 571 }
 572
 573 // Create a PLT entry for a global symbol.
 574
 575 void
 576 Target_x86_64::make_plt_entry(Symbol_table* symtab, Layout* layout,
 577                               Symbol* gsym)
 578 {
 579   if (gsym->has_plt_offset())
 580     return;
 581
 582   if (this->plt_ == NULL)
 583     {
 584       // Create the GOT sections first.
 585       this->got_section(symtab, layout);
 586
 587       this->plt_ = new Output_data_plt_x86_64(layout, this->got_plt_);
 588       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 589                                       (elfcpp::SHF_ALLOC
 590                                        | elfcpp::SHF_EXECINSTR),
 591                                       this->plt_);
 592     }
 593
 594   this->plt_->add_entry(gsym);
 595 }
 596
 597 // Handle a relocation against a non-function symbol defined in a
 598 // dynamic object.  The traditional way to handle this is to generate
 599 // a COPY relocation to copy the variable at runtime from the shared
 600 // object into the executable's data segment.  However, this is
 601 // undesirable in general, as if the size of the object changes in the
 602 // dynamic object, the executable will no longer work correctly.  If
 603 // this relocation is in a writable section, then we can create a
 604 // dynamic reloc and the dynamic linker will resolve it to the correct
 605 // address at runtime.  However, we do not want do that if the
 606 // relocation is in a read-only section, as it would prevent the
 607 // readonly segment from being shared.  And if we have to eventually
 608 // generate a COPY reloc, then any dynamic relocations will be
 609 // useless.  So this means that if this is a writable section, we need
 610 // to save the relocation until we see whether we have to create a
 611 // COPY relocation for this symbol for any other relocation.
 612
 613 void
 614 Target_x86_64::copy_reloc(const General_options* options,
 615                           Symbol_table* symtab,
 616                           Layout* layout,
 617                           Sized_relobj<64, false>* object,
 618                           unsigned int data_shndx,
 619                           Output_section* output_section,
 620                           Symbol* gsym,
 621                           const elfcpp::Rela<64, false>& rela)
 622 {
 623   Sized_symbol<64>* ssym;
 624   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(64) (gsym
 625                                                         SELECT_SIZE(64));
 626
 627   if (!Copy_relocs<64, false>::need_copy_reloc(options, object,
 628                                                data_shndx, ssym))
 629     {
 630       // So far we do not need a COPY reloc.  Save this relocation.
 631       // If it turns out that we never need a COPY reloc for this
 632       // symbol, then we will emit the relocation.
 633       if (this->copy_relocs_ == NULL)
 634         this->copy_relocs_ = new Copy_relocs<64, false>();
 635       this->copy_relocs_->save(ssym, object, data_shndx, output_section, rela);
 636     }
 637   else
 638     {
 639       // Allocate space for this symbol in the .bss section.
 640
 641       elfcpp::Elf_types<64>::Elf_WXword symsize = ssym->symsize();
 642
 643       // There is no defined way to determine the required alignment
 644       // of the symbol.  We pick the alignment based on the size.  We
 645       // set an arbitrary maximum of 256.
 646       unsigned int align;
 647       for (align = 1; align < 512; align <<= 1)
 648         if ((symsize & align) != 0)
 649           break;
 650
 651       if (this->dynbss_ == NULL)
 652         {
 653           this->dynbss_ = new Output_data_space(align);
 654           layout->add_output_section_data(".bss",
 655                                           elfcpp::SHT_NOBITS,
 656                                           (elfcpp::SHF_ALLOC
 657                                            | elfcpp::SHF_WRITE),
 658                                           this->dynbss_);
 659         }
 660
 661       Output_data_space* dynbss = this->dynbss_;
 662
 663       if (align > dynbss->addralign())
 664         dynbss->set_space_alignment(align);
 665
 666       off_t dynbss_size = dynbss->current_data_size();
 667       dynbss_size = align_address(dynbss_size, align);
 668       off_t offset = dynbss_size;
 669       dynbss->set_current_data_size(dynbss_size + symsize);
 670
 671       symtab->define_with_copy_reloc(this, ssym, dynbss, offset);
 672
 673       // Add the COPY reloc.
 674       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
 675       rela_dyn->add_global(ssym, elfcpp::R_X86_64_COPY, dynbss, offset, 0);
 676     }
 677 }
 678
 679
 680 // Optimize the TLS relocation type based on what we know about the
 681 // symbol.  IS_FINAL is true if the final address of this symbol is
 682 // known at link time.
 683
 684 tls::Tls_optimization
 685 Target_x86_64::optimize_tls_reloc(bool is_final, int r_type)
 686 {
 687   // If we are generating a shared library, then we can't do anything
 688   // in the linker.
 689   if (parameters->output_is_shared())
 690     return tls::TLSOPT_NONE;
 691
 692   switch (r_type)
 693     {
 694     case elfcpp::R_X86_64_TLSGD:
 695     case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 696     case elfcpp::R_X86_64_TLSDESC_CALL:
 697       // These are General-Dynamic which permits fully general TLS
 698       // access.  Since we know that we are generating an executable,
 699       // we can convert this to Initial-Exec.  If we also know that
 700       // this is a local symbol, we can further switch to Local-Exec.
 701       if (is_final)
 702         return tls::TLSOPT_TO_LE;
 703       return tls::TLSOPT_TO_IE;
 704
 705     case elfcpp::R_X86_64_TLSLD:
 706       // This is Local-Dynamic, which refers to a local symbol in the
 707       // dynamic TLS block.  Since we know that we generating an
 708       // executable, we can switch to Local-Exec.
 709       return tls::TLSOPT_TO_LE;
 710
 711     case elfcpp::R_X86_64_DTPOFF32:
 712     case elfcpp::R_X86_64_DTPOFF64:
 713       // Another Local-Dynamic reloc.
 714       return tls::TLSOPT_TO_LE;
 715
 716     case elfcpp::R_X86_64_GOTTPOFF:
 717       // These are Initial-Exec relocs which get the thread offset
 718       // from the GOT.  If we know that we are linking against the
 719       // local symbol, we can switch to Local-Exec, which links the
 720       // thread offset into the instruction.
 721       if (is_final)
 722         return tls::TLSOPT_TO_LE;
 723       return tls::TLSOPT_NONE;
 724
 725     case elfcpp::R_X86_64_TPOFF32:
 726       // When we already have Local-Exec, there is nothing further we
 727       // can do.
 728       return tls::TLSOPT_NONE;
 729
 730     default:
 731       gold_unreachable();
 732     }
 733 }
 734
 735 // Report an unsupported relocation against a local symbol.
 736
 737 void
 738 Target_x86_64::Scan::unsupported_reloc_local(Sized_relobj<64, false>* object,
 739                                              unsigned int r_type)
 740 {
 741   gold_error(_("%s: unsupported reloc %u against local symbol"),
 742              object->name().c_str(), r_type);
 743 }
 744
 745 // Scan a relocation for a local symbol.
 746
 747 inline void
 748 Target_x86_64::Scan::local(const General_options&,
 749                            Symbol_table* symtab,
 750                            Layout* layout,
 751                            Target_x86_64* target,
 752                            Sized_relobj<64, false>* object,
 753                            unsigned int data_shndx,
 754                            Output_section* output_section,
 755                            const elfcpp::Rela<64, false>& reloc,
 756                            unsigned int r_type,
 757                            const elfcpp::Sym<64, false>& lsym)
 758 {
 759   switch (r_type)
 760     {
 761     case elfcpp::R_X86_64_NONE:
 762     case elfcpp::R_386_GNU_VTINHERIT:
 763     case elfcpp::R_386_GNU_VTENTRY:
 764       break;
 765
 766     case elfcpp::R_X86_64_64:
 767       // If building a shared library (or a position-independent
 768       // executable), we need to create a dynamic relocation for
 769       // this location. The relocation applied at link time will
 770       // apply the link-time value, so we flag the location with
 771       // an R_386_RELATIVE relocation so the dynamic loader can
 772       // relocate it easily.
 773       if (parameters->output_is_position_independent())
 774         {
 775           Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 776           rela_dyn->add_local(object, 0, elfcpp::R_X86_64_RELATIVE,
 777                               output_section, data_shndx,
 778                               reloc.get_r_offset(), 0);
 779         }
 780       break;
 781
 782     case elfcpp::R_X86_64_32:
 783     case elfcpp::R_X86_64_32S:
 784     case elfcpp::R_X86_64_16:
 785     case elfcpp::R_X86_64_8:
 786       // If building a shared library (or a position-independent
 787       // executable), we need to create a dynamic relocation for
 788       // this location. The relocation applied at link time will
 789       // apply the link-time value, so we flag the location with
 790       // an R_386_RELATIVE relocation so the dynamic loader can
 791       // relocate it easily.
 792       if (parameters->output_is_position_independent())
 793         {
 794           Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 795           unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 796           rela_dyn->add_local(object, r_sym, r_type, output_section,
 797                               data_shndx, reloc.get_r_offset(),
 798                               reloc.get_r_addend());
 799         }
 800       break;
 801
 802     case elfcpp::R_X86_64_PC64:
 803     case elfcpp::R_X86_64_PC32:
 804     case elfcpp::R_X86_64_PC16:
 805     case elfcpp::R_X86_64_PC8:
 806       break;
 807
 808     case elfcpp::R_X86_64_PLT32:
 809       // Since we know this is a local symbol, we can handle this as a
 810       // PC32 reloc.
 811       break;
 812
 813     case elfcpp::R_X86_64_GOTPC32:
 814     case elfcpp::R_X86_64_GOTOFF64:
 815     case elfcpp::R_X86_64_GOTPC64:
 816     case elfcpp::R_X86_64_PLTOFF64:
 817       // We need a GOT section.
 818       target->got_section(symtab, layout);
 819       // For PLTOFF64, we'd normally want a PLT section, but since we
 820       // know this is a local symbol, no PLT is needed.
 821       break;
 822
 823     case elfcpp::R_X86_64_GOT64:
 824     case elfcpp::R_X86_64_GOT32:
 825     case elfcpp::R_X86_64_GOTPCREL64:
 826     case elfcpp::R_X86_64_GOTPCREL:
 827     case elfcpp::R_X86_64_GOTPLT64:
 828       {
 829         // The symbol requires a GOT entry.
 830         Output_data_got<64, false>* got = target->got_section(symtab, layout);
 831         unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 832         if (got->add_local(object, r_sym))
 833           {
 834             // If we are generating a shared object, we need to add a
 835             // dynamic relocation for this symbol's GOT entry.
 836             if (parameters->output_is_position_independent())
 837               {
 838                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 839                 // R_X86_64_RELATIVE assumes a 64-bit relocation.
 840                 if (r_type != elfcpp::R_X86_64_GOT32)
 841                   rela_dyn->add_local(object, 0, elfcpp::R_X86_64_RELATIVE,
 842                                       got, object->local_got_offset(r_sym), 0);
 843                 else
 844                   rela_dyn->add_local(object, r_sym, r_type,
 845                                       got, object->local_got_offset(r_sym), 0);
 846               }
 847           }
 848         // For GOTPLT64, we'd normally want a PLT section, but since
 849         // we know this is a local symbol, no PLT is needed.
 850       }
 851       break;
 852
 853     case elfcpp::R_X86_64_COPY:
 854     case elfcpp::R_X86_64_GLOB_DAT:
 855     case elfcpp::R_X86_64_JUMP_SLOT:
 856     case elfcpp::R_X86_64_RELATIVE:
 857       // These are outstanding tls relocs, which are unexpected when linking
 858     case elfcpp::R_X86_64_TPOFF64:
 859     case elfcpp::R_X86_64_DTPMOD64:
 860     case elfcpp::R_X86_64_TLSDESC:
 861       gold_error(_("%s: unexpected reloc %u in object file"),
 862                  object->name().c_str(), r_type);
 863       break;
 864
 865       // These are initial tls relocs, which are expected when linking
 866     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
 867     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
 868     case elfcpp::R_X86_64_TLSDESC_CALL:
 869     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
 870     case elfcpp::R_X86_64_DTPOFF32:
 871     case elfcpp::R_X86_64_DTPOFF64:
 872     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
 873     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
 874       {
 875         bool output_is_shared = parameters->output_is_shared();
 876         const tls::Tls_optimization optimized_type
 877             = Target_x86_64::optimize_tls_reloc(!output_is_shared, r_type);
 878         switch (r_type)
 879           {
 880           case elfcpp::R_X86_64_TLSGD:       // General-dynamic
 881             if (optimized_type == tls::TLSOPT_NONE)
 882               {
 883                 // Create a pair of GOT entries for the module index and
 884                 // dtv-relative offset.
 885                 Output_data_got<64, false>* got
 886                     = target->got_section(symtab, layout);
 887                 unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 888                 got->add_local_tls_with_rela(object, r_sym,
 889                                              lsym.get_st_shndx(), true,
 890                                              target->rela_dyn_section(layout),
 891                                              elfcpp::R_X86_64_DTPMOD64);
 892               }
 893             else if (optimized_type != tls::TLSOPT_TO_LE)
 894               unsupported_reloc_local(object, r_type);
 895             break;
 896
 897           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 898           case elfcpp::R_X86_64_TLSDESC_CALL:
 899             // FIXME: If not relaxing to LE, we need to generate
 900             // a GOT entry with a R_x86_64_TLSDESC reloc.
 901             if (optimized_type != tls::TLSOPT_TO_LE)
 902               unsupported_reloc_local(object, r_type);
 903             break;
 904
 905           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
 906             if (optimized_type == tls::TLSOPT_NONE)
 907               {
 908                 // Create a GOT entry for the module index.
 909                 Output_data_got<64, false>* got
 910                     = target->got_section(symtab, layout);
 911                 unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 912                 got->add_local_tls_with_rela(object, r_sym,
 913                                              lsym.get_st_shndx(), false,
 914                                              target->rela_dyn_section(layout),
 915                                              elfcpp::R_X86_64_DTPMOD64);
 916               }
 917             else if (optimized_type != tls::TLSOPT_TO_LE)
 918               unsupported_reloc_local(object, r_type);
 919             break;
 920
 921           case elfcpp::R_X86_64_DTPOFF32:
 922           case elfcpp::R_X86_64_DTPOFF64:
 923             break;
 924
 925           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
 926             if (optimized_type == tls::TLSOPT_NONE)
 927               {
 928                 // Create a GOT entry for the tp-relative offset.
 929                 Output_data_got<64, false>* got
 930                     = target->got_section(symtab, layout);
 931                 unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 932                 got->add_local_with_rela(object, r_sym,
 933                                          target->rela_dyn_section(layout),
 934                                          elfcpp::R_X86_64_TPOFF64);
 935               }
 936             else if (optimized_type != tls::TLSOPT_TO_LE)
 937               unsupported_reloc_local(object, r_type);
 938             break;
 939
 940           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
 941             if (output_is_shared)
 942               unsupported_reloc_local(object, r_type);
 943             break;
 944
 945           default:
 946             gold_unreachable();
 947           }
 948       }
 949       break;
 950
 951     case elfcpp::R_X86_64_SIZE32:
 952     case elfcpp::R_X86_64_SIZE64:
 953     default:
 954       gold_error(_("%s: unsupported reloc %u against local symbol"),
 955                  object->name().c_str(), r_type);
 956       break;
 957     }
 958 }
 959
 960
 961 // Report an unsupported relocation against a global symbol.
 962
 963 void
 964 Target_x86_64::Scan::unsupported_reloc_global(Sized_relobj<64, false>* object,
 965                                               unsigned int r_type,
 966                                               Symbol* gsym)
 967 {
 968   gold_error(_("%s: unsupported reloc %u against global symbol %s"),
 969              object->name().c_str(), r_type, gsym->demangled_name().c_str());
 970 }
 971
 972 // Scan a relocation for a global symbol.
 973
 974 inline void
 975 Target_x86_64::Scan::global(const General_options& options,
 976                             Symbol_table* symtab,
 977                             Layout* layout,
 978                             Target_x86_64* target,
 979                             Sized_relobj<64, false>* object,
 980                             unsigned int data_shndx,
 981                             Output_section* output_section,
 982                             const elfcpp::Rela<64, false>& reloc,
 983                             unsigned int r_type,
 984                             Symbol* gsym)
 985 {
 986   switch (r_type)
 987     {
 988     case elfcpp::R_X86_64_NONE:
 989     case elfcpp::R_386_GNU_VTINHERIT:
 990     case elfcpp::R_386_GNU_VTENTRY:
 991       break;
 992
 993     case elfcpp::R_X86_64_64:
 994     case elfcpp::R_X86_64_32:
 995     case elfcpp::R_X86_64_32S:
 996     case elfcpp::R_X86_64_16:
 997     case elfcpp::R_X86_64_8:
 998       {
 999         // Make a PLT entry if necessary.
1000         if (gsym->needs_plt_entry())
1001           {
1002             target->make_plt_entry(symtab, layout, gsym);
1003             // Since this is not a PC-relative relocation, we may be
1004             // taking the address of a function. In that case we need to
1005             // set the entry in the dynamic symbol table to the address of
1006             // the PLT entry.
1007             if (gsym->is_from_dynobj())
1008               gsym->set_needs_dynsym_value();
1009           }
1010         // Make a dynamic relocation if necessary.
1011         if (gsym->needs_dynamic_reloc(true, false))
1012           {
1013             if (target->may_need_copy_reloc(gsym))
1014               {
1015                 target->copy_reloc(&options, symtab, layout, object,
1016                                    data_shndx, output_section, gsym, reloc);
1017               }
1018             else if (r_type == elfcpp::R_X86_64_64
1019                      && gsym->can_use_relative_reloc(false))
1020               {
1021                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
1022                 rela_dyn->add_local(object, 0, elfcpp::R_X86_64_RELATIVE,
1023                                     output_section, data_shndx,
1024                                     reloc.get_r_offset(), 0);
1025               }
1026             else
1027               {
1028                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
1029                 rela_dyn->add_global(gsym, r_type, output_section, object,
1030                                      data_shndx, reloc.get_r_offset(),
1031                                      reloc.get_r_addend());
1032               }
1033           }
1034       }
1035       break;
1036
1037     case elfcpp::R_X86_64_PC64:
1038     case elfcpp::R_X86_64_PC32:
1039     case elfcpp::R_X86_64_PC16:
1040     case elfcpp::R_X86_64_PC8:
1041       {
1042         // Make a PLT entry if necessary.
1043         if (gsym->needs_plt_entry())
1044           target->make_plt_entry(symtab, layout, gsym);
1045         // Make a dynamic relocation if necessary.
1046         bool is_function_call = (gsym->type() == elfcpp::STT_FUNC);
1047         if (gsym->needs_dynamic_reloc(true, is_function_call))
1048           {
1049             if (target->may_need_copy_reloc(gsym))
1050               {
1051                 target->copy_reloc(&options, symtab, layout, object,
1052                                    data_shndx, output_section, gsym, reloc);
1053               }
1054             else
1055               {
1056                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
1057                 rela_dyn->add_global(gsym, r_type, output_section, object,
1058                                      data_shndx, reloc.get_r_offset(),
1059                                      reloc.get_r_addend());
1060               }
1061           }
1062       }
1063       break;
1064
1065     case elfcpp::R_X86_64_GOT64:
1066     case elfcpp::R_X86_64_GOT32:
1067     case elfcpp::R_X86_64_GOTPCREL64:
1068     case elfcpp::R_X86_64_GOTPCREL:
1069     case elfcpp::R_X86_64_GOTPLT64:
1070       {
1071         // The symbol requires a GOT entry.
1072         Output_data_got<64, false>* got = target->got_section(symtab, layout);
1073         if (gsym->final_value_is_known())
1074           got->add_global(gsym);
1075         else
1076           {
1077             // If this symbol is not fully resolved, we need to add a
1078             // dynamic relocation for it.
1079             Reloc_section* rela_dyn = target->rela_dyn_section(layout);
1080             if (gsym->is_from_dynobj() || gsym->is_preemptible())
1081               got->add_global_with_rela(gsym, rela_dyn,
1082                                         elfcpp::R_X86_64_GLOB_DAT);
1083             else
1084               {
1085                 if (got->add_global(gsym))
1086                   {
1087                     rela_dyn->add_local(object, 0, elfcpp::R_X86_64_RELATIVE,
1088                                         got, gsym->got_offset(), 0);
1089                     // Make sure we write the link-time value to the GOT.
1090                     gsym->set_needs_value_in_got();
1091                   }
1092               }
1093           }
1094         // For GOTPLT64, we also need a PLT entry (but only if the
1095         // symbol is not fully resolved).
1096         if (r_type == elfcpp::R_X86_64_GOTPLT64
1097             && !gsym->final_value_is_known())
1098           target->make_plt_entry(symtab, layout, gsym);
1099       }
1100       break;
1101
1102     case elfcpp::R_X86_64_PLT32:
1103       // If the symbol is fully resolved, this is just a PC32 reloc.
1104       // Otherwise we need a PLT entry.
1105       if (gsym->final_value_is_known())
1106         break;
1107       // If building a shared library, we can also skip the PLT entry
1108       // if the symbol is defined in the output file and is protected
1109       // or hidden.
1110       if (gsym->is_defined()
1111           && !gsym->is_from_dynobj()
1112           && !gsym->is_preemptible())
1113         break;
1114       target->make_plt_entry(symtab, layout, gsym);
1115       break;
1116
1117     case elfcpp::R_X86_64_GOTPC32:
1118     case elfcpp::R_X86_64_GOTOFF64:
1119     case elfcpp::R_X86_64_GOTPC64:
1120     case elfcpp::R_X86_64_PLTOFF64:
1121       // We need a GOT section.
1122       target->got_section(symtab, layout);
1123       // For PLTOFF64, we also need a PLT entry (but only if the
1124       // symbol is not fully resolved).
1125       if (r_type == elfcpp::R_X86_64_PLTOFF64
1126           && !gsym->final_value_is_known())
1127         target->make_plt_entry(symtab, layout, gsym);
1128       break;
1129
1130     case elfcpp::R_X86_64_COPY:
1131     case elfcpp::R_X86_64_GLOB_DAT:
1132     case elfcpp::R_X86_64_JUMP_SLOT:
1133     case elfcpp::R_X86_64_RELATIVE:
1134       // These are outstanding tls relocs, which are unexpected when linking
1135     case elfcpp::R_X86_64_TPOFF64:
1136     case elfcpp::R_X86_64_DTPMOD64:
1137     case elfcpp::R_X86_64_TLSDESC:
1138       gold_error(_("%s: unexpected reloc %u in object file"),
1139                  object->name().c_str(), r_type);
1140       break;
1141
1142       // These are initial tls relocs, which are expected for global()
1143     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1144     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1145     case elfcpp::R_X86_64_TLSDESC_CALL:
1146     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1147     case elfcpp::R_X86_64_DTPOFF32:
1148     case elfcpp::R_X86_64_DTPOFF64:
1149     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1150     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1151       {
1152         const bool is_final = gsym->final_value_is_known();
1153         const tls::Tls_optimization optimized_type
1154             = Target_x86_64::optimize_tls_reloc(is_final, r_type);
1155         switch (r_type)
1156           {
1157           case elfcpp::R_X86_64_TLSGD:       // General-dynamic
1158             if (optimized_type == tls::TLSOPT_NONE)
1159               {
1160                 // Create a pair of GOT entries for the module index and
1161                 // dtv-relative offset.
1162                 Output_data_got<64, false>* got
1163                     = target->got_section(symtab, layout);
1164                 got->add_global_tls_with_rela(gsym,
1165                                               target->rela_dyn_section(layout),
1166                                               elfcpp::R_X86_64_DTPMOD64,
1167                                               elfcpp::R_X86_64_DTPOFF64);
1168               }
1169             else if (optimized_type == tls::TLSOPT_TO_IE)
1170               {
1171                 // Create a GOT entry for the tp-relative offset.
1172                 Output_data_got<64, false>* got
1173                     = target->got_section(symtab, layout);
1174                 got->add_global_with_rela(gsym,
1175                                           target->rela_dyn_section(layout),
1176                                           elfcpp::R_X86_64_TPOFF64);
1177               }
1178             else if (optimized_type != tls::TLSOPT_TO_LE)
1179               unsupported_reloc_global(object, r_type, gsym);
1180             break;
1181
1182           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
1183           case elfcpp::R_X86_64_TLSDESC_CALL:
1184             // FIXME: If not relaxing to LE, we need to generate
1185             // DTPMOD64 and DTPOFF64, or TLSDESC, relocs.
1186             if (optimized_type != tls::TLSOPT_TO_LE)
1187               unsupported_reloc_global(object, r_type, gsym);
1188             break;
1189
1190           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
1191             if (optimized_type == tls::TLSOPT_NONE)
1192               {
1193                 // Create a GOT entry for the module index.
1194                 Output_data_got<64, false>* got
1195                     = target->got_section(symtab, layout);
1196                 got->add_global_tls_with_rela(gsym,
1197                                               target->rela_dyn_section(layout),
1198                                               elfcpp::R_X86_64_DTPMOD64);
1199               }
1200             else if (optimized_type != tls::TLSOPT_TO_LE)
1201               unsupported_reloc_global(object, r_type, gsym);
1202             break;
1203
1204           case elfcpp::R_X86_64_DTPOFF32:
1205           case elfcpp::R_X86_64_DTPOFF64:
1206             break;
1207
1208           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
1209             if (optimized_type == tls::TLSOPT_NONE)
1210               {
1211                 // Create a GOT entry for the tp-relative offset.
1212                 Output_data_got<64, false>* got
1213                     = target->got_section(symtab, layout);
1214                 got->add_global_with_rela(gsym,
1215                                           target->rela_dyn_section(layout),
1216                                           elfcpp::R_X86_64_TPOFF64);
1217               }
1218             else if (optimized_type != tls::TLSOPT_TO_LE)
1219               unsupported_reloc_global(object, r_type, gsym);
1220             break;
1221
1222           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
1223             if (parameters->output_is_shared())
1224               unsupported_reloc_local(object, r_type);
1225             break;
1226
1227           default:
1228             gold_unreachable();
1229           }
1230       }
1231       break;
1232
1233     case elfcpp::R_X86_64_SIZE32:
1234     case elfcpp::R_X86_64_SIZE64:
1235     default:
1236       gold_error(_("%s: unsupported reloc %u against global symbol %s"),
1237                  object->name().c_str(), r_type,
1238                  gsym->demangled_name().c_str());
1239       break;
1240     }
1241 }
1242
1243 // Scan relocations for a section.
1244
1245 void
1246 Target_x86_64::scan_relocs(const General_options& options,
1247                            Symbol_table* symtab,
1248                            Layout* layout,
1249                            Sized_relobj<64, false>* object,
1250                            unsigned int data_shndx,
1251                            unsigned int sh_type,
1252                            const unsigned char* prelocs,
1253                            size_t reloc_count,
1254                            Output_section* output_section,
1255                            bool needs_special_offset_handling,
1256                            size_t local_symbol_count,
1257                            const unsigned char* plocal_symbols)
1258 {
1259   if (sh_type == elfcpp::SHT_REL)
1260     {
1261       gold_error(_("%s: unsupported REL reloc section"),
1262                  object->name().c_str());
1263       return;
1264     }
1265
1266   gold::scan_relocs<64, false, Target_x86_64, elfcpp::SHT_RELA,
1267       Target_x86_64::Scan>(
1268     options,
1269     symtab,
1270     layout,
1271     this,
1272     object,
1273     data_shndx,
1274     prelocs,
1275     reloc_count,
1276     output_section,
1277     needs_special_offset_handling,
1278     local_symbol_count,
1279     plocal_symbols);
1280 }
1281
1282 // Finalize the sections.
1283
1284 void
1285 Target_x86_64::do_finalize_sections(Layout* layout)
1286 {
1287   // Fill in some more dynamic tags.
1288   Output_data_dynamic* const odyn = layout->dynamic_data();
1289   if (odyn != NULL)
1290     {
1291       if (this->got_plt_ != NULL)
1292         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1293
1294       if (this->plt_ != NULL)
1295         {
1296           const Output_data* od = this->plt_->rel_plt();
1297           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1298           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1299           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_RELA);
1300         }
1301
1302       if (this->rela_dyn_ != NULL)
1303         {
1304           const Output_data* od = this->rela_dyn_;
1305           odyn->add_section_address(elfcpp::DT_RELA, od);
1306           odyn->add_section_size(elfcpp::DT_RELASZ, od);
1307           odyn->add_constant(elfcpp::DT_RELAENT,
1308                              elfcpp::Elf_sizes<64>::rela_size);
1309         }
1310
1311       if (!parameters->output_is_shared())
1312         {
1313           // The value of the DT_DEBUG tag is filled in by the dynamic
1314           // linker at run time, and used by the debugger.
1315           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1316         }
1317     }
1318
1319   // Emit any relocs we saved in an attempt to avoid generating COPY
1320   // relocs.
1321   if (this->copy_relocs_ == NULL)
1322     return;
1323   if (this->copy_relocs_->any_to_emit())
1324     {
1325       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
1326       this->copy_relocs_->emit(rela_dyn);
1327     }
1328   delete this->copy_relocs_;
1329   this->copy_relocs_ = NULL;
1330 }
1331
1332 // Perform a relocation.
1333
1334 inline bool
1335 Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo,
1336                                   Target_x86_64* target,
1337                                   size_t relnum,
1338                                   const elfcpp::Rela<64, false>& rela,
1339                                   unsigned int r_type,
1340                                   const Sized_symbol<64>* gsym,
1341                                   const Symbol_value<64>* psymval,
1342                                   unsigned char* view,
1343                                   elfcpp::Elf_types<64>::Elf_Addr address,
1344                                   off_t view_size)
1345 {
1346   if (this->skip_call_tls_get_addr_)
1347     {
1348       if (r_type != elfcpp::R_X86_64_PLT32
1349           || gsym == NULL
1350           || strcmp(gsym->name(), "__tls_get_addr") != 0)
1351         {
1352           gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1353                                  _("missing expected TLS relocation"));
1354         }
1355       else
1356         {
1357           this->skip_call_tls_get_addr_ = false;
1358           return false;
1359         }
1360     }
1361
1362   // Pick the value to use for symbols defined in shared objects.
1363   Symbol_value<64> symval;
1364   if (gsym != NULL
1365       && (gsym->is_from_dynobj()
1366           || (parameters->output_is_shared()
1367               && gsym->is_preemptible()))
1368       && gsym->has_plt_offset())
1369     {
1370       symval.set_output_value(target->plt_section()->address()
1371                               + gsym->plt_offset());
1372       psymval = &symval;
1373     }
1374
1375   const Sized_relobj<64, false>* object = relinfo->object;
1376   const elfcpp::Elf_Xword addend = rela.get_r_addend();
1377
1378   // Get the GOT offset if needed.
1379   // The GOT pointer points to the end of the GOT section.
1380   // We need to subtract the size of the GOT section to get
1381   // the actual offset to use in the relocation.
1382   bool have_got_offset = false;
1383   unsigned int got_offset = 0;
1384   switch (r_type)
1385     {
1386     case elfcpp::R_X86_64_GOT32:
1387     case elfcpp::R_X86_64_GOT64:
1388     case elfcpp::R_X86_64_GOTPLT64:
1389     case elfcpp::R_X86_64_GOTPCREL:
1390     case elfcpp::R_X86_64_GOTPCREL64:
1391       if (gsym != NULL)
1392         {
1393           gold_assert(gsym->has_got_offset());
1394           got_offset = gsym->got_offset() - target->got_size();
1395         }
1396       else
1397         {
1398           unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1399           gold_assert(object->local_has_got_offset(r_sym));
1400           got_offset = object->local_got_offset(r_sym) - target->got_size();
1401         }
1402       have_got_offset = true;
1403       break;
1404
1405     default:
1406       break;
1407     }
1408
1409   switch (r_type)
1410     {
1411     case elfcpp::R_X86_64_NONE:
1412     case elfcpp::R_386_GNU_VTINHERIT:
1413     case elfcpp::R_386_GNU_VTENTRY:
1414       break;
1415
1416     case elfcpp::R_X86_64_64:
1417       Relocate_functions<64, false>::rela64(view, object, psymval, addend);
1418       break;
1419
1420     case elfcpp::R_X86_64_PC64:
1421       Relocate_functions<64, false>::pcrela64(view, object, psymval, addend,
1422                                               address);
1423       break;
1424
1425     case elfcpp::R_X86_64_32:
1426       // FIXME: we need to verify that value + addend fits into 32 bits:
1427       //    uint64_t x = value + addend;
1428       //    x == static_cast<uint64_t>(static_cast<uint32_t>(x))
1429       // Likewise for other <=32-bit relocations (but see R_X86_64_32S).
1430       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1431       break;
1432
1433     case elfcpp::R_X86_64_32S:
1434       // FIXME: we need to verify that value + addend fits into 32 bits:
1435       //    int64_t x = value + addend;   // note this quantity is signed!
1436       //    x == static_cast<int64_t>(static_cast<int32_t>(x))
1437       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1438       break;
1439
1440     case elfcpp::R_X86_64_PC32:
1441       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1442                                               address);
1443       break;
1444
1445     case elfcpp::R_X86_64_16:
1446       Relocate_functions<64, false>::rela16(view, object, psymval, addend);
1447       break;
1448
1449     case elfcpp::R_X86_64_PC16:
1450       Relocate_functions<64, false>::pcrela16(view, object, psymval, addend,
1451                                               address);
1452       break;
1453
1454     case elfcpp::R_X86_64_8:
1455       Relocate_functions<64, false>::rela8(view, object, psymval, addend);
1456       break;
1457
1458     case elfcpp::R_X86_64_PC8:
1459       Relocate_functions<64, false>::pcrela8(view, object, psymval, addend,
1460                                              address);
1461       break;
1462
1463     case elfcpp::R_X86_64_PLT32:
1464       gold_assert(gsym == NULL
1465                   || gsym->has_plt_offset()
1466                   || gsym->final_value_is_known());
1467       // Note: while this code looks the same as for R_X86_64_PC32, it
1468       // behaves differently because psymval was set to point to
1469       // the PLT entry, rather than the symbol, in Scan::global().
1470       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1471                                               address);
1472       break;
1473
1474     case elfcpp::R_X86_64_PLTOFF64:
1475       {
1476         gold_assert(gsym);
1477         gold_assert(gsym->has_plt_offset()
1478                     || gsym->final_value_is_known());
1479         elfcpp::Elf_types<64>::Elf_Addr got_address;
1480         got_address = target->got_section(NULL, NULL)->address();
1481         Relocate_functions<64, false>::rela64(view, object, psymval,
1482                                               addend - got_address);
1483       }
1484
1485     case elfcpp::R_X86_64_GOT32:
1486       gold_assert(have_got_offset);
1487       Relocate_functions<64, false>::rela32(view, got_offset, addend);
1488       break;
1489
1490     case elfcpp::R_X86_64_GOTPC32:
1491       {
1492         gold_assert(gsym);
1493         elfcpp::Elf_types<64>::Elf_Addr value;
1494         value = target->got_plt_section()->address();
1495         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1496       }
1497       break;
1498
1499     case elfcpp::R_X86_64_GOT64:
1500       // The ABI doc says "Like GOT64, but indicates a PLT entry is needed."
1501       // Since we always add a PLT entry, this is equivalent.
1502     case elfcpp::R_X86_64_GOTPLT64:
1503       gold_assert(have_got_offset);
1504       Relocate_functions<64, false>::rela64(view, got_offset, addend);
1505       break;
1506
1507     case elfcpp::R_X86_64_GOTPC64:
1508       {
1509         gold_assert(gsym);
1510         elfcpp::Elf_types<64>::Elf_Addr value;
1511         value = target->got_plt_section()->address();
1512         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1513       }
1514       break;
1515
1516     case elfcpp::R_X86_64_GOTOFF64:
1517       {
1518         elfcpp::Elf_types<64>::Elf_Addr value;
1519         value = (psymval->value(object, 0)
1520                  - target->got_plt_section()->address());
1521         Relocate_functions<64, false>::rela64(view, value, addend);
1522       }
1523       break;
1524
1525     case elfcpp::R_X86_64_GOTPCREL:
1526       {
1527         gold_assert(have_got_offset);
1528         elfcpp::Elf_types<64>::Elf_Addr value;
1529         value = target->got_plt_section()->address() + got_offset;
1530         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1531       }
1532       break;
1533
1534     case elfcpp::R_X86_64_GOTPCREL64:
1535       {
1536         gold_assert(have_got_offset);
1537         elfcpp::Elf_types<64>::Elf_Addr value;
1538         value = target->got_plt_section()->address() + got_offset;
1539         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1540       }
1541       break;
1542
1543     case elfcpp::R_X86_64_COPY:
1544     case elfcpp::R_X86_64_GLOB_DAT:
1545     case elfcpp::R_X86_64_JUMP_SLOT:
1546     case elfcpp::R_X86_64_RELATIVE:
1547       // These are outstanding tls relocs, which are unexpected when linking
1548     case elfcpp::R_X86_64_TPOFF64:
1549     case elfcpp::R_X86_64_DTPMOD64:
1550     case elfcpp::R_X86_64_TLSDESC:
1551       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1552                              _("unexpected reloc %u in object file"),
1553                              r_type);
1554       break;
1555
1556       // These are initial tls relocs, which are expected when linking
1557     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1558     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1559     case elfcpp::R_X86_64_TLSDESC_CALL:
1560     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1561     case elfcpp::R_X86_64_DTPOFF32:
1562     case elfcpp::R_X86_64_DTPOFF64:
1563     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1564     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1565       this->relocate_tls(relinfo, target, relnum, rela, r_type, gsym, psymval,
1566                          view, address, view_size);
1567       break;
1568
1569     case elfcpp::R_X86_64_SIZE32:
1570     case elfcpp::R_X86_64_SIZE64:
1571     default:
1572       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1573                              _("unsupported reloc %u"),
1574                              r_type);
1575       break;
1576     }
1577
1578   return true;
1579 }
1580
1581 // Perform a TLS relocation.
1582
1583 inline void
1584 Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo,
1585                                       Target_x86_64* target,
1586                                       size_t relnum,
1587                                       const elfcpp::Rela<64, false>& rela,
1588                                       unsigned int r_type,
1589                                       const Sized_symbol<64>* gsym,
1590                                       const Symbol_value<64>* psymval,
1591                                       unsigned char* view,
1592                                       elfcpp::Elf_types<64>::Elf_Addr,
1593                                       off_t view_size)
1594 {
1595   Output_segment* tls_segment = relinfo->layout->tls_segment();
1596
1597   const Sized_relobj<64, false>* object = relinfo->object;
1598
1599   elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0);
1600
1601   const bool is_final = (gsym == NULL
1602                          ? !parameters->output_is_position_independent()
1603                          : gsym->final_value_is_known());
1604   const tls::Tls_optimization optimized_type
1605       = Target_x86_64::optimize_tls_reloc(is_final, r_type);
1606   switch (r_type)
1607     {
1608     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1609     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1610     case elfcpp::R_X86_64_TLSDESC_CALL:
1611       if (optimized_type == tls::TLSOPT_TO_LE)
1612         {
1613           gold_assert(tls_segment != NULL);
1614           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1615                              rela, r_type, value, view,
1616                              view_size);
1617           break;
1618         }
1619       else
1620         {
1621           unsigned int got_offset;
1622           if (gsym != NULL)
1623             {
1624               gold_assert(gsym->has_tls_got_offset(true));
1625               got_offset = gsym->tls_got_offset(true) - target->got_size();
1626             }
1627           else
1628             {
1629               unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1630               gold_assert(object->local_has_tls_got_offset(r_sym, true));
1631               got_offset = (object->local_tls_got_offset(r_sym, true)
1632                             - target->got_size());
1633             }
1634           if (optimized_type == tls::TLSOPT_TO_IE)
1635             {
1636               gold_assert(tls_segment != NULL);
1637               this->tls_gd_to_ie(relinfo, relnum, tls_segment, rela, r_type,
1638                                  got_offset, view, view_size);
1639               break;
1640             }
1641           else if (optimized_type == tls::TLSOPT_NONE)
1642             {
1643               // Relocate the field with the offset of the pair of GOT
1644               // entries.
1645               Relocate_functions<64, false>::rel64(view, got_offset);
1646               break;
1647             }
1648         }
1649       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1650                              _("unsupported reloc %u"), r_type);
1651       break;
1652
1653     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1654       if (optimized_type == tls::TLSOPT_TO_LE)
1655         {
1656           gold_assert(tls_segment != NULL);
1657           this->tls_ld_to_le(relinfo, relnum, tls_segment, rela, r_type,
1658                              value, view, view_size);
1659           break;
1660         }
1661       else if (optimized_type == tls::TLSOPT_NONE)
1662         {
1663           // Relocate the field with the offset of the GOT entry for
1664           // the module index.
1665           unsigned int got_offset;
1666           if (gsym != NULL)
1667             {
1668               gold_assert(gsym->has_tls_got_offset(false));
1669               got_offset = gsym->tls_got_offset(false) - target->got_size();
1670             }
1671           else
1672             {
1673               unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1674               gold_assert(object->local_has_tls_got_offset(r_sym, false));
1675               got_offset = (object->local_tls_got_offset(r_sym, false)
1676                             - target->got_size());
1677             }
1678           Relocate_functions<64, false>::rel64(view, got_offset);
1679           break;
1680         }
1681       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1682                              _("unsupported reloc %u"), r_type);
1683       break;
1684
1685     case elfcpp::R_X86_64_DTPOFF32:
1686       gold_assert(tls_segment != NULL);
1687       if (optimized_type == tls::TLSOPT_TO_LE)
1688         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1689       else
1690         value = value - tls_segment->vaddr();
1691       Relocate_functions<64, false>::rel32(view, value);
1692       break;
1693
1694     case elfcpp::R_X86_64_DTPOFF64:
1695       gold_assert(tls_segment != NULL);
1696       if (optimized_type == tls::TLSOPT_TO_LE)
1697         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1698       else
1699         value = value - tls_segment->vaddr();
1700       Relocate_functions<64, false>::rel64(view, value);
1701       break;
1702
1703     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1704       if (optimized_type == tls::TLSOPT_TO_LE)
1705         {
1706           gold_assert(tls_segment != NULL);
1707           Target_x86_64::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1708                                                 rela, r_type, value, view,
1709                                                 view_size);
1710           break;
1711         }
1712       else if (optimized_type == tls::TLSOPT_NONE)
1713         {
1714           // Relocate the field with the offset of the GOT entry for
1715           // the tp-relative offset of the symbol.
1716           unsigned int got_offset;
1717           if (gsym != NULL)
1718             {
1719               gold_assert(gsym->has_got_offset());
1720               got_offset = gsym->got_offset() - target->got_size();
1721             }
1722           else
1723             {
1724               unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1725               gold_assert(object->local_has_got_offset(r_sym));
1726               got_offset = (object->local_got_offset(r_sym)
1727                             - target->got_size());
1728             }
1729           Relocate_functions<64, false>::rel64(view, got_offset);
1730           break;
1731         }
1732       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1733                              _("unsupported reloc type %u"),
1734                              r_type);
1735       break;
1736
1737     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1738       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1739       Relocate_functions<64, false>::rel32(view, value);
1740       break;
1741     }
1742 }
1743
1744 // Do a relocation in which we convert a TLS General-Dynamic to an
1745 // Initial-Exec.
1746
1747 inline void
1748 Target_x86_64::Relocate::tls_gd_to_ie(const Relocate_info<64, false>* relinfo,
1749                                       size_t relnum,
1750                                       Output_segment* tls_segment,
1751                                       const elfcpp::Rela<64, false>& rela,
1752                                       unsigned int,
1753                                       elfcpp::Elf_types<64>::Elf_Addr value,
1754                                       unsigned char* view,
1755                                       off_t view_size)
1756 {
1757   // .byte 0x66; leaq foo@tlsgd(%rip),%rdi;
1758   // .word 0x6666; rex64; call __tls_get_addr
1759   // ==> movq %fs:0,%rax; addq x@gottpoff(%rip),%rax
1760
1761   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4);
1762   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12);
1763
1764   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1765                  (memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0));
1766   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1767                  (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0));
1768
1769   memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x03\x05\0\0\0\0", 16);
1770
1771   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1772   Relocate_functions<64, false>::rela32(view + 8, value, 0);
1773
1774   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1775   // We can skip it.
1776   this->skip_call_tls_get_addr_ = true;
1777 }
1778
1779 // Do a relocation in which we convert a TLS General-Dynamic to a
1780 // Local-Exec.
1781
1782 inline void
1783 Target_x86_64::Relocate::tls_gd_to_le(const Relocate_info<64, false>* relinfo,
1784                                       size_t relnum,
1785                                       Output_segment* tls_segment,
1786                                       const elfcpp::Rela<64, false>& rela,
1787                                       unsigned int,
1788                                       elfcpp::Elf_types<64>::Elf_Addr value,
1789                                       unsigned char* view,
1790                                       off_t view_size)
1791 {
1792   // .byte 0x66; leaq foo@tlsgd(%rip),%rdi;
1793   // .word 0x6666; rex64; call __tls_get_addr
1794   // ==> movq %fs:0,%rax; leaq x@tpoff(%rax),%rax
1795
1796   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4);
1797   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12);
1798
1799   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1800                  (memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0));
1801   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1802                  (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0));
1803
1804   memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x8d\x80\0\0\0\0", 16);
1805
1806   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1807   Relocate_functions<64, false>::rela32(view + 8, value, 0);
1808
1809   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1810   // We can skip it.
1811   this->skip_call_tls_get_addr_ = true;
1812 }
1813
1814 inline void
1815 Target_x86_64::Relocate::tls_ld_to_le(const Relocate_info<64, false>* relinfo,
1816                                       size_t relnum,
1817                                       Output_segment*,
1818                                       const elfcpp::Rela<64, false>& rela,
1819                                       unsigned int,
1820                                       elfcpp::Elf_types<64>::Elf_Addr,
1821                                       unsigned char* view,
1822                                       off_t view_size)
1823 {
1824   // leaq foo@tlsld(%rip),%rdi; call __tls_get_addr@plt;
1825   // ... leq foo@dtpoff(%rax),%reg
1826   // ==> .word 0x6666; .byte 0x66; movq %fs:0,%rax ... leaq x@tpoff(%rax),%rdx
1827
1828   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1829   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 9);
1830
1831   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1832                  view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x3d);
1833
1834   tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[4] == 0xe8);
1835
1836   memcpy(view - 3, "\x66\x66\x66\x64\x48\x8b\x04\x25\0\0\0\0", 12);
1837
1838   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1839   // We can skip it.
1840   this->skip_call_tls_get_addr_ = true;
1841 }
1842
1843 // Do a relocation in which we convert a TLS Initial-Exec to a
1844 // Local-Exec.
1845
1846 inline void
1847 Target_x86_64::Relocate::tls_ie_to_le(const Relocate_info<64, false>* relinfo,
1848                                       size_t relnum,
1849                                       Output_segment* tls_segment,
1850                                       const elfcpp::Rela<64, false>& rela,
1851                                       unsigned int,
1852                                       elfcpp::Elf_types<64>::Elf_Addr value,
1853                                       unsigned char* view,
1854                                       off_t view_size)
1855 {
1856   // We need to examine the opcodes to figure out which instruction we
1857   // are looking at.
1858
1859   // movq foo@gottpoff(%rip),%reg  ==>  movq $YY,%reg
1860   // addq foo@gottpoff(%rip),%reg  ==>  addq $YY,%reg
1861
1862   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1863   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 4);
1864
1865   unsigned char op1 = view[-3];
1866   unsigned char op2 = view[-2];
1867   unsigned char op3 = view[-1];
1868   unsigned char reg = op3 >> 3;
1869
1870   if (op2 == 0x8b)
1871     {
1872       // movq
1873       if (op1 == 0x4c)
1874         view[-3] = 0x49;
1875       view[-2] = 0xc7;
1876       view[-1] = 0xc0 | reg;
1877     }
1878   else if (reg == 4)
1879     {
1880       // Special handling for %rsp.
1881       if (op1 == 0x4c)
1882         view[-3] = 0x49;
1883       view[-2] = 0x81;
1884       view[-1] = 0xc0 | reg;
1885     }
1886   else
1887     {
1888       // addq
1889       if (op1 == 0x4c)
1890         view[-3] = 0x4d;
1891       view[-2] = 0x8d;
1892       view[-1] = 0x80 | reg | (reg << 3);
1893     }
1894
1895   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1896   Relocate_functions<64, false>::rela32(view, value, 0);
1897 }
1898
1899 // Relocate section data.
1900
1901 void
1902 Target_x86_64::relocate_section(const Relocate_info<64, false>* relinfo,
1903                                 unsigned int sh_type,
1904                                 const unsigned char* prelocs,
1905                                 size_t reloc_count,
1906                                 Output_section* output_section,
1907                                 bool needs_special_offset_handling,
1908                                 unsigned char* view,
1909                                 elfcpp::Elf_types<64>::Elf_Addr address,
1910                                 off_t view_size)
1911 {
1912   gold_assert(sh_type == elfcpp::SHT_RELA);
1913
1914   gold::relocate_section<64, false, Target_x86_64, elfcpp::SHT_RELA,
1915                          Target_x86_64::Relocate>(
1916     relinfo,
1917     this,
1918     prelocs,
1919     reloc_count,
1920     output_section,
1921     needs_special_offset_handling,
1922     view,
1923     address,
1924     view_size);
1925 }
1926
1927 // Return the value to use for a dynamic which requires special
1928 // treatment.  This is how we support equality comparisons of function
1929 // pointers across shared library boundaries, as described in the
1930 // processor specific ABI supplement.
1931
1932 uint64_t
1933 Target_x86_64::do_dynsym_value(const Symbol* gsym) const
1934 {
1935   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1936   return this->plt_section()->address() + gsym->plt_offset();
1937 }
1938
1939 // Return a string used to fill a code section with nops to take up
1940 // the specified length.
1941
1942 std::string
1943 Target_x86_64::do_code_fill(off_t length)
1944 {
1945   if (length >= 16)
1946     {
1947       // Build a jmpq instruction to skip over the bytes.
1948       unsigned char jmp[5];
1949       jmp[0] = 0xe9;
1950       elfcpp::Swap_unaligned<64, false>::writeval(jmp + 1, length - 5);
1951       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1952               + std::string(length - 5, '\0'));
1953     }
1954
1955   // Nop sequences of various lengths.
1956   const char nop1[1] = { 0x90 };                   // nop
1957   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1958   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1959   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1960   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1961                          0x00 };                   // leal 0(%esi,1),%esi
1962   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1963                          0x00, 0x00 };
1964   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1965                          0x00, 0x00, 0x00 };
1966   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1967                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1968   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1969                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1970                          0x00 };
1971   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1972                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1973                            0x00, 0x00 };
1974   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1975                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1976                            0x00, 0x00, 0x00 };
1977   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1978                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1979                            0x00, 0x00, 0x00, 0x00 };
1980   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1981                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1982                            0x27, 0x00, 0x00, 0x00,
1983                            0x00 };
1984   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1985                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1986                            0xbc, 0x27, 0x00, 0x00,
1987                            0x00, 0x00 };
1988   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1989                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1990                            0x90, 0x90, 0x90, 0x90,
1991                            0x90, 0x90, 0x90 };
1992
1993   const char* nops[16] = {
1994     NULL,
1995     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1996     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1997   };
1998
1999   return std::string(nops[length], length);
2000 }
2001
2002 // The selector for x86_64 object files.
2003
2004 class Target_selector_x86_64 : public Target_selector
2005 {
2006 public:
2007   Target_selector_x86_64()
2008     : Target_selector(elfcpp::EM_X86_64, 64, false)
2009   { }
2010
2011   Target*
2012   recognize(int machine, int osabi, int abiversion);
2013
2014  private:
2015   Target_x86_64* target_;
2016 };
2017
2018 // Recognize an x86_64 object file when we already know that the machine
2019 // number is EM_X86_64.
2020
2021 Target*
2022 Target_selector_x86_64::recognize(int, int, int)
2023 {
2024   if (this->target_ == NULL)
2025     this->target_ = new Target_x86_64();
2026   return this->target_;
2027 }
2028
2029 Target_selector_x86_64 target_selector_x86_64;
2030
2031 } // End anonymous namespace.