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