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"));
 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 General-Dynamic to Local-Exec transition.
 178     inline void
 179     tls_gd_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 Local-Dynamic to Local-Exec transition.
 187     inline void
 188     tls_ld_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     // Do a TLS Initial-Exec to Local-Exec transition.
 196     static inline void
 197     tls_ie_to_le(const Relocate_info<64, false>*, size_t relnum,
 198                  Output_segment* tls_segment,
 199                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 200                  elfcpp::Elf_types<64>::Elf_Addr value,
 201                  unsigned char* view,
 202                  off_t view_size);
 203
 204     // This is set if we should skip the next reloc, which should be a
 205     // PLT32 reloc against ___tls_get_addr.
 206     bool skip_call_tls_get_addr_;
 207   };
 208
 209   // Adjust TLS relocation type based on the options and whether this
 210   // is a local symbol.
 211   static tls::Tls_optimization
 212   optimize_tls_reloc(bool is_final, int r_type);
 213
 214   // Get the GOT section, creating it if necessary.
 215   Output_data_got<64, false>*
 216   got_section(Symbol_table*, Layout*);
 217
 218   // Create a PLT entry for a global symbol.
 219   void
 220   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 221
 222   // Get the PLT section.
 223   Output_data_plt_x86_64*
 224   plt_section() const
 225   {
 226     gold_assert(this->plt_ != NULL);
 227     return this->plt_;
 228   }
 229
 230   // Get the dynamic reloc section, creating it if necessary.
 231   Reloc_section*
 232   rela_dyn_section(Layout*);
 233
 234   // Copy a relocation against a global symbol.
 235   void
 236   copy_reloc(const General_options*, Symbol_table*, Layout*,
 237              Sized_relobj<64, false>*, unsigned int,
 238              Symbol*, const elfcpp::Rela<64, false>&);
 239
 240   // Information about this specific target which we pass to the
 241   // general Target structure.
 242   static const Target::Target_info x86_64_info;
 243
 244   // The GOT section.
 245   Output_data_got<64, false>* got_;
 246   // The PLT section.
 247   Output_data_plt_x86_64* plt_;
 248   // The GOT PLT section.
 249   Output_data_space* got_plt_;
 250   // The dynamic reloc section.
 251   Reloc_section* rela_dyn_;
 252   // Relocs saved to avoid a COPY reloc.
 253   Copy_relocs<64, false>* copy_relocs_;
 254   // Space for variables copied with a COPY reloc.
 255   Output_data_space* dynbss_;
 256 };
 257
 258 const Target::Target_info Target_x86_64::x86_64_info =
 259 {
 260   64,                   // size
 261   false,                // is_big_endian
 262   elfcpp::EM_X86_64,    // machine_code
 263   false,                // has_make_symbol
 264   false,                // has_resolve
 265   true,                 // has_code_fill
 266   true,                 // is_default_stack_executable
 267   "/lib/ld64.so.1",     // program interpreter
 268   0x400000,             // default_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>& rela)
 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, rela);
 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       symtab->define_with_copy_reloc(this, ssym, dynbss, offset);
 626
 627       // Add the COPY reloc.
 628       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
 629       rela_dyn->add_global(ssym, elfcpp::R_X86_64_COPY, dynbss, offset, 0);
 630     }
 631 }
 632
 633
 634 // Optimize the TLS relocation type based on what we know about the
 635 // symbol.  IS_FINAL is true if the final address of this symbol is
 636 // known at link time.
 637
 638 tls::Tls_optimization
 639 Target_x86_64::optimize_tls_reloc(bool is_final, int r_type)
 640 {
 641   // If we are generating a shared library, then we can't do anything
 642   // in the linker.
 643   if (parameters->output_is_shared())
 644     return tls::TLSOPT_NONE;
 645
 646   switch (r_type)
 647     {
 648     case elfcpp::R_X86_64_TLSGD:
 649     case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 650     case elfcpp::R_X86_64_TLSDESC_CALL:
 651       // These are General-Dynamic which permits fully general TLS
 652       // access.  Since we know that we are generating an executable,
 653       // we can convert this to Initial-Exec.  If we also know that
 654       // this is a local symbol, we can further switch to Local-Exec.
 655       if (is_final)
 656         return tls::TLSOPT_TO_LE;
 657       return tls::TLSOPT_TO_IE;
 658
 659     case elfcpp::R_X86_64_TLSLD:
 660       // This is Local-Dynamic, which refers to a local symbol in the
 661       // dynamic TLS block.  Since we know that we generating an
 662       // executable, we can switch to Local-Exec.
 663       return tls::TLSOPT_TO_LE;
 664
 665     case elfcpp::R_X86_64_DTPOFF32:
 666     case elfcpp::R_X86_64_DTPOFF64:
 667       // Another Local-Dynamic reloc.
 668       return tls::TLSOPT_TO_LE;
 669
 670     case elfcpp::R_X86_64_GOTTPOFF:
 671       // These are Initial-Exec relocs which get the thread offset
 672       // from the GOT.  If we know that we are linking against the
 673       // local symbol, we can switch to Local-Exec, which links the
 674       // thread offset into the instruction.
 675       if (is_final)
 676         return tls::TLSOPT_TO_LE;
 677       return tls::TLSOPT_NONE;
 678
 679     case elfcpp::R_X86_64_TPOFF32:
 680       // When we already have Local-Exec, there is nothing further we
 681       // can do.
 682       return tls::TLSOPT_NONE;
 683
 684     default:
 685       gold_unreachable();
 686     }
 687 }
 688
 689 // Report an unsupported relocation against a local symbol.
 690
 691 void
 692 Target_x86_64::Scan::unsupported_reloc_local(Sized_relobj<64, false>* object,
 693                                              unsigned int r_type)
 694 {
 695   gold_error(_("%s: unsupported reloc %u against local symbol"),
 696              object->name().c_str(), r_type);
 697 }
 698
 699 // Scan a relocation for a local symbol.
 700
 701 inline void
 702 Target_x86_64::Scan::local(const General_options&,
 703                            Symbol_table* symtab,
 704                            Layout* layout,
 705                            Target_x86_64* target,
 706                            Sized_relobj<64, false>* object,
 707                            unsigned int data_shndx,
 708                            const elfcpp::Rela<64, false>& reloc,
 709                            unsigned int r_type,
 710                            const elfcpp::Sym<64, false>&)
 711 {
 712   switch (r_type)
 713     {
 714     case elfcpp::R_X86_64_NONE:
 715     case elfcpp::R_386_GNU_VTINHERIT:
 716     case elfcpp::R_386_GNU_VTENTRY:
 717       break;
 718
 719     case elfcpp::R_X86_64_64:
 720     case elfcpp::R_X86_64_32:
 721     case elfcpp::R_X86_64_32S:
 722     case elfcpp::R_X86_64_16:
 723     case elfcpp::R_X86_64_8:
 724       // FIXME: If we are generating a shared object we need to copy
 725       // this relocation into the object.
 726       gold_assert(!parameters->output_is_shared());
 727       break;
 728
 729     case elfcpp::R_X86_64_PC64:
 730     case elfcpp::R_X86_64_PC32:
 731     case elfcpp::R_X86_64_PC16:
 732     case elfcpp::R_X86_64_PC8:
 733       break;
 734
 735     case elfcpp::R_X86_64_PLT32:
 736       // Since we know this is a local symbol, we can handle this as a
 737       // PC32 reloc.
 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:            // Global-dynamic
 784     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
 785     case elfcpp::R_X86_64_TLSDESC_CALL:
 786     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
 787     case elfcpp::R_X86_64_DTPOFF32:
 788     case elfcpp::R_X86_64_DTPOFF64:
 789     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
 790     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
 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_TLSGD:       // General-dynamic
 798           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 799           case elfcpp::R_X86_64_TLSDESC_CALL:
 800             // FIXME: If not relaxing to LE, we need to generate
 801             // DTPMOD64 and DTPOFF64 relocs.
 802             if (optimized_type != tls::TLSOPT_TO_LE)
 803               unsupported_reloc_local(object, r_type);
 804             break;
 805
 806           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
 807           case elfcpp::R_X86_64_DTPOFF32:
 808           case elfcpp::R_X86_64_DTPOFF64:
 809             // FIXME: If not relaxing to LE, we need to generate a
 810             // DTPMOD64 reloc.
 811             if (optimized_type != tls::TLSOPT_TO_LE)
 812               unsupported_reloc_local(object, r_type);
 813             break;
 814
 815           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
 816             // FIXME: If not relaxing to LE, we need to generate a
 817             // TPOFF64 reloc.
 818             if (optimized_type != tls::TLSOPT_TO_LE)
 819               unsupported_reloc_local(object, r_type);
 820             break;
 821
 822           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
 823             // FIXME: If generating a shared object, we need to copy
 824             // this relocation into the object.
 825             gold_assert(!output_is_shared);
 826             break;
 827
 828           default:
 829             gold_unreachable();
 830           }
 831       }
 832       break;
 833
 834     case elfcpp::R_X86_64_GOTPLT64:
 835     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
 836     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
 837     default:
 838       gold_error(_("%s: unsupported reloc %u against local symbol"),
 839                  object->name().c_str(), r_type);
 840       break;
 841     }
 842 }
 843
 844
 845 // Report an unsupported relocation against a global symbol.
 846
 847 void
 848 Target_x86_64::Scan::unsupported_reloc_global(Sized_relobj<64, false>* object,
 849                                               unsigned int r_type,
 850                                               Symbol* gsym)
 851 {
 852   gold_error(_("%s: unsupported reloc %u against global symbol %s"),
 853              object->name().c_str(), r_type, gsym->name());
 854 }
 855
 856 // Scan a relocation for a global symbol.
 857
 858 inline void
 859 Target_x86_64::Scan::global(const General_options& options,
 860                             Symbol_table* symtab,
 861                             Layout* layout,
 862                             Target_x86_64* target,
 863                             Sized_relobj<64, false>* object,
 864                             unsigned int data_shndx,
 865                             const elfcpp::Rela<64, false>& reloc,
 866                             unsigned int r_type,
 867                             Symbol* gsym)
 868 {
 869   switch (r_type)
 870     {
 871     case elfcpp::R_X86_64_NONE:
 872     case elfcpp::R_386_GNU_VTINHERIT:
 873     case elfcpp::R_386_GNU_VTENTRY:
 874       break;
 875
 876     case elfcpp::R_X86_64_64:
 877     case elfcpp::R_X86_64_PC64:
 878     case elfcpp::R_X86_64_32:
 879     case elfcpp::R_X86_64_32S:
 880     case elfcpp::R_X86_64_PC32:
 881     case elfcpp::R_X86_64_16:
 882     case elfcpp::R_X86_64_PC16:
 883     case elfcpp::R_X86_64_8:
 884     case elfcpp::R_X86_64_PC8:
 885       // FIXME: If we are generating a shared object we may need to
 886       // copy this relocation into the object.  If this symbol is
 887       // defined in a shared object, we may need to copy this
 888       // relocation in order to avoid a COPY relocation.
 889       gold_assert(!parameters->output_is_shared());
 890
 891       if (gsym->is_from_dynobj())
 892         {
 893           // This symbol is defined in a dynamic object.  If it is a
 894           // function, we make a PLT entry.  Otherwise we need to
 895           // either generate a COPY reloc or copy this reloc.
 896           if (gsym->type() == elfcpp::STT_FUNC)
 897             {
 898               target->make_plt_entry(symtab, layout, gsym);
 899
 900               // If this is not a PC relative reference, then we may
 901               // be taking the address of the function.  In that case
 902               // we need to set the entry in the dynamic symbol table
 903               // to the address of the PLT entry.
 904               if (r_type != elfcpp::R_X86_64_PC64
 905                   && r_type != elfcpp::R_X86_64_PC32
 906                   && r_type != elfcpp::R_X86_64_PC16
 907                   && r_type != elfcpp::R_X86_64_PC8)
 908                 gsym->set_needs_dynsym_value();
 909             }
 910           else
 911             target->copy_reloc(&options, symtab, layout, object, data_shndx,
 912                                gsym, reloc);
 913         }
 914
 915       break;
 916
 917     case elfcpp::R_X86_64_GOT64:
 918     case elfcpp::R_X86_64_GOT32:
 919     case elfcpp::R_X86_64_GOTPCREL64:
 920     case elfcpp::R_X86_64_GOTPCREL:
 921     case elfcpp::R_X86_64_GOTPLT64:
 922       {
 923         // The symbol requires a GOT entry.
 924         Output_data_got<64, false>* got = target->got_section(symtab, layout);
 925         if (got->add_global(gsym))
 926           {
 927             // If this symbol is not fully resolved, we need to add a
 928             // dynamic relocation for it.
 929             if (!gsym->final_value_is_known())
 930               {
 931                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 932                 rela_dyn->add_global(gsym, elfcpp::R_X86_64_GLOB_DAT, got,
 933                                      gsym->got_offset(), 0);
 934               }
 935           }
 936       }
 937       break;
 938
 939     case elfcpp::R_X86_64_PLT32:
 940       // If the symbol is fully resolved, this is just a PC32 reloc.
 941       // Otherwise we need a PLT entry.
 942       if (gsym->final_value_is_known())
 943         break;
 944       target->make_plt_entry(symtab, layout, gsym);
 945       break;
 946
 947     case elfcpp::R_X86_64_GOTPC32:  // TODO(csilvers): correct?
 948     case elfcpp::R_X86_64_GOTOFF64:
 949     case elfcpp::R_X86_64_GOTPC64:  // TODO(csilvers): correct?
 950     case elfcpp::R_X86_64_PLTOFF64:  // TODO(csilvers): correct?
 951       // We need a GOT section.
 952       target->got_section(symtab, layout);
 953       break;
 954
 955     case elfcpp::R_X86_64_COPY:
 956     case elfcpp::R_X86_64_GLOB_DAT:
 957     case elfcpp::R_X86_64_JUMP_SLOT:
 958     case elfcpp::R_X86_64_RELATIVE:
 959       // These are outstanding tls relocs, which are unexpected when linking
 960     case elfcpp::R_X86_64_TPOFF64:
 961     case elfcpp::R_X86_64_DTPMOD64:
 962     case elfcpp::R_X86_64_TLSDESC:
 963       gold_error(_("%s: unexpected reloc %u in object file"),
 964                  object->name().c_str(), r_type);
 965       break;
 966
 967       // These are initial tls relocs, which are expected for global()
 968     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
 969     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
 970     case elfcpp::R_X86_64_TLSDESC_CALL:
 971     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
 972     case elfcpp::R_X86_64_DTPOFF32:
 973     case elfcpp::R_X86_64_DTPOFF64:
 974     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
 975     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
 976       {
 977         const bool is_final = gsym->final_value_is_known();
 978         const tls::Tls_optimization optimized_type
 979             = Target_x86_64::optimize_tls_reloc(is_final, r_type);
 980         switch (r_type)
 981           {
 982           case elfcpp::R_X86_64_TLSGD:       // General-dynamic
 983           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 984           case elfcpp::R_X86_64_TLSDESC_CALL:
 985             // FIXME: If not relaxing to LE, we need to generate
 986             // DTPMOD64 and DTPOFF64, or TLSDESC, relocs.
 987             if (optimized_type != tls::TLSOPT_TO_LE)
 988               unsupported_reloc_global(object, r_type, gsym);
 989             break;
 990
 991           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
 992           case elfcpp::R_X86_64_DTPOFF32:
 993           case elfcpp::R_X86_64_DTPOFF64:
 994             // FIXME: If not relaxing to LE, we need to generate a
 995             // DTPMOD64 reloc.
 996             if (optimized_type != tls::TLSOPT_TO_LE)
 997               unsupported_reloc_global(object, r_type, gsym);
 998             break;
 999
1000           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
1001             // FIXME: If not relaxing to LE, we need to generate a
1002             // TPOFF64 reloc.
1003             if (optimized_type != tls::TLSOPT_TO_LE)
1004               unsupported_reloc_global(object, r_type, gsym);
1005             break;
1006
1007           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
1008             // FIXME: If generating a shared object, we need to copy
1009             // this relocation into the object.
1010             gold_assert(is_final);
1011             break;
1012
1013           default:
1014             gold_unreachable();
1015           }
1016       }
1017       break;
1018     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
1019     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
1020     default:
1021       gold_error(_("%s: unsupported reloc %u against global symbol %s"),
1022                  object->name().c_str(), r_type, gsym->name());
1023       break;
1024     }
1025 }
1026
1027 // Scan relocations for a section.
1028
1029 void
1030 Target_x86_64::scan_relocs(const General_options& options,
1031                            Symbol_table* symtab,
1032                            Layout* layout,
1033                            Sized_relobj<64, false>* object,
1034                            unsigned int data_shndx,
1035                            unsigned int sh_type,
1036                            const unsigned char* prelocs,
1037                            size_t reloc_count,
1038                            size_t local_symbol_count,
1039                            const unsigned char* plocal_symbols,
1040                            Symbol** global_symbols)
1041 {
1042   if (sh_type == elfcpp::SHT_REL)
1043     {
1044       gold_error(_("%s: unsupported REL reloc section"),
1045                  object->name().c_str());
1046       return;
1047     }
1048
1049   gold::scan_relocs<64, false, Target_x86_64, elfcpp::SHT_RELA,
1050       Target_x86_64::Scan>(
1051     options,
1052     symtab,
1053     layout,
1054     this,
1055     object,
1056     data_shndx,
1057     prelocs,
1058     reloc_count,
1059     local_symbol_count,
1060     plocal_symbols,
1061     global_symbols);
1062 }
1063
1064 // Finalize the sections.
1065
1066 void
1067 Target_x86_64::do_finalize_sections(Layout* layout)
1068 {
1069   // Fill in some more dynamic tags.
1070   Output_data_dynamic* const odyn = layout->dynamic_data();
1071   if (odyn != NULL)
1072     {
1073       if (this->got_plt_ != NULL)
1074         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1075
1076       if (this->plt_ != NULL)
1077         {
1078           const Output_data* od = this->plt_->rel_plt();
1079           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1080           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1081           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_RELA);
1082         }
1083
1084       if (this->rela_dyn_ != NULL)
1085         {
1086           const Output_data* od = this->rela_dyn_;
1087           odyn->add_section_address(elfcpp::DT_RELA, od);
1088           odyn->add_section_size(elfcpp::DT_RELASZ, od);
1089           odyn->add_constant(elfcpp::DT_RELAENT,
1090                              elfcpp::Elf_sizes<64>::rela_size);
1091         }
1092
1093       if (!parameters->output_is_shared())
1094         {
1095           // The value of the DT_DEBUG tag is filled in by the dynamic
1096           // linker at run time, and used by the debugger.
1097           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1098         }
1099     }
1100
1101   // Emit any relocs we saved in an attempt to avoid generating COPY
1102   // relocs.
1103   if (this->copy_relocs_ == NULL)
1104     return;
1105   if (this->copy_relocs_->any_to_emit())
1106     {
1107       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
1108       this->copy_relocs_->emit(rela_dyn);
1109     }
1110   delete this->copy_relocs_;
1111   this->copy_relocs_ = NULL;
1112 }
1113
1114 // Perform a relocation.
1115
1116 inline bool
1117 Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo,
1118                                   Target_x86_64* target,
1119                                   size_t relnum,
1120                                   const elfcpp::Rela<64, false>& rela,
1121                                   unsigned int r_type,
1122                                   const Sized_symbol<64>* gsym,
1123                                   const Symbol_value<64>* psymval,
1124                                   unsigned char* view,
1125                                   elfcpp::Elf_types<64>::Elf_Addr address,
1126                                   off_t view_size)
1127 {
1128   if (this->skip_call_tls_get_addr_)
1129     {
1130       if (r_type != elfcpp::R_X86_64_PLT32
1131           || gsym == NULL
1132           || strcmp(gsym->name(), "__tls_get_addr") != 0)
1133         {
1134           gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1135                                  _("missing expected TLS relocation"));
1136         }
1137       else
1138         {
1139           this->skip_call_tls_get_addr_ = false;
1140           return false;
1141         }
1142     }
1143
1144   // Pick the value to use for symbols defined in shared objects.
1145   Symbol_value<64> symval;
1146   if (gsym != NULL && gsym->is_from_dynobj() && gsym->has_plt_offset())
1147     {
1148       symval.set_output_value(target->plt_section()->address()
1149                               + gsym->plt_offset());
1150       psymval = &symval;
1151     }
1152
1153   const Sized_relobj<64, false>* object = relinfo->object;
1154   const elfcpp::Elf_Xword addend = rela.get_r_addend();
1155
1156   // Get the GOT offset if needed.
1157   bool have_got_offset = false;
1158   unsigned int got_offset = 0;
1159   switch (r_type)
1160     {
1161     case elfcpp::R_X86_64_GOT32:
1162     case elfcpp::R_X86_64_GOT64:
1163     case elfcpp::R_X86_64_GOTPLT64:
1164     case elfcpp::R_X86_64_GOTPCREL:
1165     case elfcpp::R_X86_64_GOTPCREL64:
1166       if (gsym != NULL)
1167         {
1168           gold_assert(gsym->has_got_offset());
1169           got_offset = gsym->got_offset();
1170         }
1171       else
1172         {
1173           unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1174           got_offset = object->local_got_offset(r_sym);
1175         }
1176       have_got_offset = true;
1177       break;
1178
1179     default:
1180       break;
1181     }
1182
1183   switch (r_type)
1184     {
1185     case elfcpp::R_X86_64_NONE:
1186     case elfcpp::R_386_GNU_VTINHERIT:
1187     case elfcpp::R_386_GNU_VTENTRY:
1188       break;
1189
1190     case elfcpp::R_X86_64_64:
1191       Relocate_functions<64, false>::rela64(view, object, psymval, addend);
1192       break;
1193
1194     case elfcpp::R_X86_64_PC64:
1195       Relocate_functions<64, false>::pcrela64(view, object, psymval, addend,
1196                                               address);
1197       break;
1198
1199     case elfcpp::R_X86_64_32:
1200       // FIXME: we need to verify that value + addend fits into 32 bits:
1201       //    uint64_t x = value + addend;
1202       //    x == static_cast<uint64_t>(static_cast<uint32_t>(x))
1203       // Likewise for other <=32-bit relocations (but see R_X86_64_32S).
1204       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1205       break;
1206
1207     case elfcpp::R_X86_64_32S:
1208       // FIXME: we need to verify that value + addend fits into 32 bits:
1209       //    int64_t x = value + addend;   // note this quantity is signed!
1210       //    x == static_cast<int64_t>(static_cast<int32_t>(x))
1211       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1212       break;
1213
1214     case elfcpp::R_X86_64_PC32:
1215       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1216                                               address);
1217       break;
1218
1219     case elfcpp::R_X86_64_16:
1220       Relocate_functions<64, false>::rela16(view, object, psymval, addend);
1221       break;
1222
1223     case elfcpp::R_X86_64_PC16:
1224       Relocate_functions<64, false>::pcrela16(view, object, psymval, addend,
1225                                               address);
1226       break;
1227
1228     case elfcpp::R_X86_64_8:
1229       Relocate_functions<64, false>::rela8(view, object, psymval, addend);
1230       break;
1231
1232     case elfcpp::R_X86_64_PC8:
1233       Relocate_functions<64, false>::pcrela8(view, object, psymval, addend,
1234                                              address);
1235       break;
1236
1237     case elfcpp::R_X86_64_PLT32:
1238       gold_assert(gsym == NULL
1239                   || gsym->has_plt_offset()
1240                   || gsym->final_value_is_known());
1241       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1242                                               address);
1243       break;
1244
1245     case elfcpp::R_X86_64_GOT32:
1246       gold_assert(have_got_offset);
1247       Relocate_functions<64, false>::rela32(view, got_offset, addend);
1248       break;
1249
1250     case elfcpp::R_X86_64_GOTPC32:
1251       {
1252         gold_assert(gsym);
1253         elfcpp::Elf_types<64>::Elf_Addr value;
1254         value = target->got_section(NULL, NULL)->address();
1255         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1256       }
1257       break;
1258
1259     case elfcpp::R_X86_64_GOT64:
1260       // The ABI doc says "Like GOT64, but indicates a PLT entry is needed."
1261       // Since we always add a PLT entry, this is equivalent.
1262     case elfcpp::R_X86_64_GOTPLT64:  // TODO(csilvers): correct?
1263       gold_assert(have_got_offset);
1264       Relocate_functions<64, false>::rela64(view, got_offset, addend);
1265       break;
1266
1267     case elfcpp::R_X86_64_GOTPC64:
1268       {
1269         gold_assert(gsym);
1270         elfcpp::Elf_types<64>::Elf_Addr value;
1271         value = target->got_section(NULL, NULL)->address();
1272         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1273       }
1274       break;
1275
1276     case elfcpp::R_X86_64_GOTOFF64:
1277       {
1278         elfcpp::Elf_types<64>::Elf_Addr value;
1279         value = (psymval->value(object, 0)
1280                  - target->got_section(NULL, NULL)->address());
1281         Relocate_functions<64, false>::rela64(view, value, addend);
1282       }
1283       break;
1284
1285     case elfcpp::R_X86_64_GOTPCREL:
1286       {
1287         gold_assert(have_got_offset);
1288         elfcpp::Elf_types<64>::Elf_Addr value;
1289         value = target->got_section(NULL, NULL)->address() + got_offset;
1290         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1291       }
1292       break;
1293
1294     case elfcpp::R_X86_64_GOTPCREL64:
1295       {
1296         gold_assert(have_got_offset);
1297         elfcpp::Elf_types<64>::Elf_Addr value;
1298         value = target->got_section(NULL, NULL)->address() + got_offset;
1299         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1300       }
1301       break;
1302
1303     case elfcpp::R_X86_64_COPY:
1304     case elfcpp::R_X86_64_GLOB_DAT:
1305     case elfcpp::R_X86_64_JUMP_SLOT:
1306     case elfcpp::R_X86_64_RELATIVE:
1307       // These are outstanding tls relocs, which are unexpected when linking
1308     case elfcpp::R_X86_64_TPOFF64:
1309     case elfcpp::R_X86_64_DTPMOD64:
1310     case elfcpp::R_X86_64_TLSDESC:
1311       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1312                              _("unexpected reloc %u in object file"),
1313                              r_type);
1314       break;
1315
1316       // These are initial tls relocs, which are expected when linking
1317     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1318     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1319     case elfcpp::R_X86_64_TLSDESC_CALL:
1320     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1321     case elfcpp::R_X86_64_DTPOFF32:
1322     case elfcpp::R_X86_64_DTPOFF64:
1323     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1324     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1325       this->relocate_tls(relinfo, relnum, rela, r_type, gsym, psymval, view,
1326                          address, view_size);
1327       break;
1328
1329     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
1330     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
1331     case elfcpp::R_X86_64_PLTOFF64:  // TODO(csilvers): implement me!
1332     default:
1333       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1334                              _("unsupported reloc %u"),
1335                              r_type);
1336       break;
1337     }
1338
1339   return true;
1340 }
1341
1342 // Perform a TLS relocation.
1343
1344 inline void
1345 Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo,
1346                                       size_t relnum,
1347                                       const elfcpp::Rela<64, false>& rela,
1348                                       unsigned int r_type,
1349                                       const Sized_symbol<64>* gsym,
1350                                       const Symbol_value<64>* psymval,
1351                                       unsigned char* view,
1352                                       elfcpp::Elf_types<64>::Elf_Addr,
1353                                       off_t view_size)
1354 {
1355   Output_segment* tls_segment = relinfo->layout->tls_segment();
1356   if (tls_segment == NULL)
1357     {
1358       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1359                              _("TLS reloc but no TLS segment"));
1360       return;
1361     }
1362
1363   elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0);
1364
1365   const bool is_final = (gsym == NULL
1366                          ? !parameters->output_is_shared()
1367                          : gsym->final_value_is_known());
1368   const tls::Tls_optimization optimized_type
1369       = Target_x86_64::optimize_tls_reloc(is_final, r_type);
1370   switch (r_type)
1371     {
1372     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1373     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1374     case elfcpp::R_X86_64_TLSDESC_CALL:
1375       if (optimized_type == tls::TLSOPT_TO_LE)
1376         {
1377           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1378                              rela, r_type, value, view,
1379                              view_size);
1380           break;
1381         }
1382       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1383                              _("unsupported reloc %u"), r_type);
1384       break;
1385
1386     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1387       if (optimized_type == tls::TLSOPT_TO_LE)
1388         {
1389           this->tls_ld_to_le(relinfo, relnum, tls_segment, rela, r_type,
1390                              value, view, view_size);
1391           break;
1392         }
1393       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1394                              _("unsupported reloc %u"), r_type);
1395       break;
1396
1397     case elfcpp::R_X86_64_DTPOFF32:
1398       if (optimized_type == tls::TLSOPT_TO_LE)
1399         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1400       else
1401         value = value - tls_segment->vaddr();
1402       Relocate_functions<64, false>::rel32(view, value);
1403       break;
1404
1405     case elfcpp::R_X86_64_DTPOFF64:
1406       if (optimized_type == tls::TLSOPT_TO_LE)
1407         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1408       else
1409         value = value - tls_segment->vaddr();
1410       Relocate_functions<64, false>::rel64(view, value);
1411       break;
1412
1413     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1414       if (optimized_type == tls::TLSOPT_TO_LE)
1415         {
1416           Target_x86_64::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1417                                                 rela, r_type, value, view,
1418                                                 view_size);
1419           break;
1420         }
1421       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1422                              _("unsupported reloc type %u"),
1423                              r_type);
1424       break;
1425
1426     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1427       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1428       Relocate_functions<64, false>::rel32(view, value);
1429       break;
1430     }
1431 }
1432
1433 // Do a relocation in which we convert a TLS General-Dynamic to a
1434 // Local-Exec.
1435
1436 inline void
1437 Target_x86_64::Relocate::tls_gd_to_le(const Relocate_info<64, false>* relinfo,
1438                                       size_t relnum,
1439                                       Output_segment* tls_segment,
1440                                       const elfcpp::Rela<64, false>& rela,
1441                                       unsigned int,
1442                                       elfcpp::Elf_types<64>::Elf_Addr value,
1443                                       unsigned char* view,
1444                                       off_t view_size)
1445 {
1446   // .byte 0x66; leaq foo@tlsgd(%rip),%rdi;
1447   // .word 0x6666; rex64; call __tls_get_addr
1448   // ==> movq %fs:0,%rax; leaq x@tpoff(%rax),%rax
1449
1450   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4);
1451   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12);
1452
1453   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1454                  (memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0));
1455   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1456                  (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0));
1457
1458   memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x8d\x80\0\0\0\0", 16);
1459
1460   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1461   Relocate_functions<64, false>::rela32(view + 8, value, 0);
1462
1463   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1464   // We can skip it.
1465   this->skip_call_tls_get_addr_ = true;
1466 }
1467
1468 inline void
1469 Target_x86_64::Relocate::tls_ld_to_le(const Relocate_info<64, false>* relinfo,
1470                                       size_t relnum,
1471                                       Output_segment*,
1472                                       const elfcpp::Rela<64, false>& rela,
1473                                       unsigned int,
1474                                       elfcpp::Elf_types<64>::Elf_Addr,
1475                                       unsigned char* view,
1476                                       off_t view_size)
1477 {
1478   // leaq foo@tlsld(%rip),%rdi; call __tls_get_addr@plt;
1479   // ... leq foo@dtpoff(%rax),%reg
1480   // ==> .word 0x6666; .byte 0x66; movq %fs:0,%rax ... leaq x@tpoff(%rax),%rdx
1481
1482   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1483   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 9);
1484
1485   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1486                  view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x3d);
1487
1488   tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[4] == 0xe8);
1489
1490   memcpy(view - 3, "\x66\x66\x66\x64\x48\x8b\x04\x25\0\0\0\0", 12);
1491
1492   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1493   // We can skip it.
1494   this->skip_call_tls_get_addr_ = true;
1495 }
1496
1497 // Do a relocation in which we convert a TLS Initial-Exec to a
1498 // Local-Exec.
1499
1500 inline void
1501 Target_x86_64::Relocate::tls_ie_to_le(const Relocate_info<64, false>* relinfo,
1502                                       size_t relnum,
1503                                       Output_segment* tls_segment,
1504                                       const elfcpp::Rela<64, false>& rela,
1505                                       unsigned int,
1506                                       elfcpp::Elf_types<64>::Elf_Addr value,
1507                                       unsigned char* view,
1508                                       off_t view_size)
1509 {
1510   // We need to examine the opcodes to figure out which instruction we
1511   // are looking at.
1512
1513   // movq foo@gottpoff(%rip),%reg  ==>  movq $YY,%reg
1514   // addq foo@gottpoff(%rip),%reg  ==>  addq $YY,%reg
1515
1516   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1517   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 4);
1518
1519   unsigned char op1 = view[-3];
1520   unsigned char op2 = view[-2];
1521   unsigned char op3 = view[-1];
1522   unsigned char reg = op3 >> 3;
1523
1524   if (op2 == 0x8b)
1525     {
1526       // movq
1527       if (op1 == 0x4c)
1528         view[-3] = 0x49;
1529       view[-2] = 0xc7;
1530       view[-1] = 0xc0 | reg;
1531     }
1532   else if (reg == 4)
1533     {
1534       // Special handling for %rsp.
1535       if (op1 == 0x4c)
1536         view[-3] = 0x49;
1537       view[-2] = 0x81;
1538       view[-1] = 0xc0 | reg;
1539     }
1540   else
1541     {
1542       // addq
1543       if (op1 == 0x4c)
1544         view[-3] = 0x4d;
1545       view[-2] = 0x8d;
1546       view[-1] = 0x80 | reg | (reg << 3);
1547     }
1548
1549   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1550   Relocate_functions<64, false>::rela32(view, value, 0);
1551 }
1552
1553 // Relocate section data.
1554
1555 void
1556 Target_x86_64::relocate_section(const Relocate_info<64, false>* relinfo,
1557                                 unsigned int sh_type,
1558                                 const unsigned char* prelocs,
1559                                 size_t reloc_count,
1560                                 unsigned char* view,
1561                                 elfcpp::Elf_types<64>::Elf_Addr address,
1562                                 off_t view_size)
1563 {
1564   gold_assert(sh_type == elfcpp::SHT_RELA);
1565
1566   gold::relocate_section<64, false, Target_x86_64, elfcpp::SHT_RELA,
1567                          Target_x86_64::Relocate>(
1568     relinfo,
1569     this,
1570     prelocs,
1571     reloc_count,
1572     view,
1573     address,
1574     view_size);
1575 }
1576
1577 // Return the value to use for a dynamic which requires special
1578 // treatment.  This is how we support equality comparisons of function
1579 // pointers across shared library boundaries, as described in the
1580 // processor specific ABI supplement.
1581
1582 uint64_t
1583 Target_x86_64::do_dynsym_value(const Symbol* gsym) const
1584 {
1585   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1586   return this->plt_section()->address() + gsym->plt_offset();
1587 }
1588
1589 // Return a string used to fill a code section with nops to take up
1590 // the specified length.
1591
1592 std::string
1593 Target_x86_64::do_code_fill(off_t length)
1594 {
1595   if (length >= 16)
1596     {
1597       // Build a jmpq instruction to skip over the bytes.
1598       unsigned char jmp[5];
1599       jmp[0] = 0xe9;
1600       elfcpp::Swap_unaligned<64, false>::writeval(jmp + 1, length - 5);
1601       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1602               + std::string(length - 5, '\0'));
1603     }
1604
1605   // Nop sequences of various lengths.
1606   const char nop1[1] = { 0x90 };                   // nop
1607   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1608   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1609   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1610   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1611                          0x00 };                   // leal 0(%esi,1),%esi
1612   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1613                          0x00, 0x00 };
1614   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1615                          0x00, 0x00, 0x00 };
1616   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1617                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1618   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1619                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1620                          0x00 };
1621   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1622                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1623                            0x00, 0x00 };
1624   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1625                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1626                            0x00, 0x00, 0x00 };
1627   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1628                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1629                            0x00, 0x00, 0x00, 0x00 };
1630   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1631                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1632                            0x27, 0x00, 0x00, 0x00,
1633                            0x00 };
1634   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1635                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1636                            0xbc, 0x27, 0x00, 0x00,
1637                            0x00, 0x00 };
1638   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1639                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1640                            0x90, 0x90, 0x90, 0x90,
1641                            0x90, 0x90, 0x90 };
1642
1643   const char* nops[16] = {
1644     NULL,
1645     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1646     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1647   };
1648
1649   return std::string(nops[length], length);
1650 }
1651
1652 // The selector for x86_64 object files.
1653
1654 class Target_selector_x86_64 : public Target_selector
1655 {
1656 public:
1657   Target_selector_x86_64()
1658     : Target_selector(elfcpp::EM_X86_64, 64, false)
1659   { }
1660
1661   Target*
1662   recognize(int machine, int osabi, int abiversion);
1663
1664  private:
1665   Target_x86_64* target_;
1666 };
1667
1668 // Recognize an x86_64 object file when we already know that the machine
1669 // number is EM_X86_64.
1670
1671 Target*
1672 Target_selector_x86_64::recognize(int, int, int)
1673 {
1674   if (this->target_ == NULL)
1675     this->target_ = new Target_x86_64();
1676   return this->target_;
1677 }
1678
1679 Target_selector_x86_64 target_selector_x86_64;
1680
1681 } // End anonymous namespace.