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 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     // Do a TLS Local-Dynamic to Local-Exec transition.
 196     inline void
 197     tls_ld_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   "/lib/ld64.so.1",     // program interpreter
 267   0x400000,             // default_text_segment_address
 268   0x1000,               // abi_pagesize
 269   0x1000                // common_pagesize
 270 };
 271
 272 // Get the GOT section, creating it if necessary.
 273
 274 Output_data_got<64, false>*
 275 Target_x86_64::got_section(Symbol_table* symtab, Layout* layout)
 276 {
 277   if (this->got_ == NULL)
 278     {
 279       gold_assert(symtab != NULL && layout != NULL);
 280
 281       this->got_ = new Output_data_got<64, false>();
 282
 283       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 284                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 285                                       this->got_);
 286
 287       // The old GNU linker creates a .got.plt section.  We just
 288       // create another set of data in the .got section.  Note that we
 289       // always create a PLT if we create a GOT, although the PLT
 290       // might be empty.
 291       // TODO(csilvers): do we really need an alignment of 8?
 292       this->got_plt_ = new Output_data_space(8);
 293       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 294                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 295                                       this->got_plt_);
 296
 297       // The first three entries are reserved.
 298       this->got_plt_->set_space_size(3 * 8);
 299
 300       // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
 301       symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
 302                                     this->got_plt_,
 303                                     0, 0, elfcpp::STT_OBJECT,
 304                                     elfcpp::STB_LOCAL,
 305                                     elfcpp::STV_HIDDEN, 0,
 306                                     false, false);
 307     }
 308
 309   return this->got_;
 310 }
 311
 312 // Get the dynamic reloc section, creating it if necessary.
 313
 314 Target_x86_64::Reloc_section*
 315 Target_x86_64::rela_dyn_section(Layout* layout)
 316 {
 317   if (this->rela_dyn_ == NULL)
 318     {
 319       gold_assert(layout != NULL);
 320       this->rela_dyn_ = new Reloc_section();
 321       layout->add_output_section_data(".rela.dyn", elfcpp::SHT_RELA,
 322                                       elfcpp::SHF_ALLOC, this->rela_dyn_);
 323     }
 324   return this->rela_dyn_;
 325 }
 326
 327 // A class to handle the PLT data.
 328
 329 class Output_data_plt_x86_64 : public Output_section_data
 330 {
 331  public:
 332   typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
 333
 334   Output_data_plt_x86_64(Layout*, Output_data_space*);
 335
 336   // Add an entry to the PLT.
 337   void
 338   add_entry(Symbol* gsym);
 339
 340   // Return the .rel.plt section data.
 341   const Reloc_section*
 342   rel_plt() const
 343   { return this->rel_; }
 344
 345  protected:
 346   void
 347   do_adjust_output_section(Output_section* os);
 348
 349  private:
 350   // The size of an entry in the PLT.
 351   static const int plt_entry_size = 16;
 352
 353   // The first entry in the PLT.
 354   // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same
 355   // procedure linkage table for both programs and shared objects."
 356   static unsigned char first_plt_entry[plt_entry_size];
 357
 358   // Other entries in the PLT for an executable.
 359   static unsigned char plt_entry[plt_entry_size];
 360
 361   // Set the final size.
 362   void
 363   do_set_address(uint64_t, off_t)
 364   { this->set_data_size((this->count_ + 1) * plt_entry_size); }
 365
 366   // Write out the PLT data.
 367   void
 368   do_write(Output_file*);
 369
 370   // The reloc section.
 371   Reloc_section* rel_;
 372   // The .got.plt section.
 373   Output_data_space* got_plt_;
 374   // The number of PLT entries.
 375   unsigned int count_;
 376 };
 377
 378 // Create the PLT section.  The ordinary .got section is an argument,
 379 // since we need to refer to the start.  We also create our own .got
 380 // section just for PLT entries.
 381
 382 Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout,
 383                                                Output_data_space* got_plt)
 384     // TODO(csilvers): do we really need an alignment of 8?
 385   : Output_section_data(8), got_plt_(got_plt), count_(0)
 386 {
 387   this->rel_ = new Reloc_section();
 388   layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
 389                                   elfcpp::SHF_ALLOC, this->rel_);
 390 }
 391
 392 void
 393 Output_data_plt_x86_64::do_adjust_output_section(Output_section* os)
 394 {
 395   // UnixWare sets the entsize of .plt to 4, and so does the old GNU
 396   // linker, and so do we.
 397   os->set_entsize(4);
 398 }
 399
 400 // Add an entry to the PLT.
 401
 402 void
 403 Output_data_plt_x86_64::add_entry(Symbol* gsym)
 404 {
 405   gold_assert(!gsym->has_plt_offset());
 406
 407   // Note that when setting the PLT offset we skip the initial
 408   // reserved PLT entry.
 409   gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
 410
 411   ++this->count_;
 412
 413   off_t got_offset = this->got_plt_->data_size();
 414
 415   // Every PLT entry needs a GOT entry which points back to the PLT
 416   // entry (this will be changed by the dynamic linker, normally
 417   // lazily when the function is called).
 418   this->got_plt_->set_space_size(got_offset + 8);
 419
 420   // Every PLT entry needs a reloc.
 421   gsym->set_needs_dynsym_entry();
 422   this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_,
 423                          got_offset, 0);
 424
 425   // Note that we don't need to save the symbol.  The contents of the
 426   // PLT are independent of which symbols are used.  The symbols only
 427   // appear in the relocations.
 428 }
 429
 430 // The first entry in the PLT for an executable.
 431
 432 unsigned char Output_data_plt_x86_64::first_plt_entry[plt_entry_size] =
 433 {
 434   // From AMD64 ABI Draft 0.98, page 76
 435   0xff, 0x35,   // pushq contents of memory address
 436   0, 0, 0, 0,   // replaced with address of .got + 4
 437   0xff, 0x25,   // jmp indirect
 438   0, 0, 0, 0,   // replaced with address of .got + 8
 439   0x90, 0x90, 0x90, 0x90   // noop (x4)
 440 };
 441
 442 // Subsequent entries in the PLT for an executable.
 443
 444 unsigned char Output_data_plt_x86_64::plt_entry[plt_entry_size] =
 445 {
 446   // From AMD64 ABI Draft 0.98, page 76
 447   0xff, 0x25,   // jmpq indirect
 448   0, 0, 0, 0,   // replaced with address of symbol in .got
 449   0x68,         // pushq immediate
 450   0, 0, 0, 0,   // replaced with offset into relocation table
 451   0xe9,         // jmpq relative
 452   0, 0, 0, 0    // replaced with offset to start of .plt
 453 };
 454
 455 // Write out the PLT.  This uses the hand-coded instructions above,
 456 // and adjusts them as needed.  This is specified by the AMD64 ABI.
 457
 458 void
 459 Output_data_plt_x86_64::do_write(Output_file* of)
 460 {
 461   const off_t offset = this->offset();
 462   const off_t oview_size = this->data_size();
 463   unsigned char* const oview = of->get_output_view(offset, oview_size);
 464
 465   const off_t got_file_offset = this->got_plt_->offset();
 466   const off_t got_size = this->got_plt_->data_size();
 467   unsigned char* const got_view = of->get_output_view(got_file_offset,
 468                                                       got_size);
 469
 470   unsigned char* pov = oview;
 471
 472   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
 473   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 474
 475   memcpy(pov, first_plt_entry, plt_entry_size);
 476   if (!parameters->output_is_shared())
 477     {
 478       // We do a jmp relative to the PC at the end of this instruction.
 479       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 8
 480                                                   - (plt_address + 6));
 481       elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 16
 482                                         - (plt_address + 12));
 483     }
 484   pov += plt_entry_size;
 485
 486   unsigned char* got_pov = got_view;
 487
 488   memset(got_pov, 0, 24);
 489   got_pov += 24;
 490
 491   unsigned int plt_offset = plt_entry_size;
 492   unsigned int got_offset = 24;
 493   const unsigned int count = this->count_;
 494   for (unsigned int plt_index = 0;
 495        plt_index < count;
 496        ++plt_index,
 497          pov += plt_entry_size,
 498          got_pov += 8,
 499          plt_offset += plt_entry_size,
 500          got_offset += 8)
 501     {
 502       // Set and adjust the PLT entry itself.
 503       memcpy(pov, plt_entry, plt_entry_size);
 504       if (parameters->output_is_shared())
 505         // FIXME(csilvers): what's the right thing to write here?
 506         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
 507       else
 508         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 509                                                     (got_address + got_offset
 510                                                      - (plt_address + plt_offset
 511                                                         + 6)));
 512
 513       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_index);
 514       elfcpp::Swap<32, false>::writeval(pov + 12,
 515                                         - (plt_offset + plt_entry_size));
 516
 517       // Set the entry in the GOT.
 518       elfcpp::Swap<64, false>::writeval(got_pov, plt_address + plt_offset + 6);
 519     }
 520
 521   gold_assert(pov - oview == oview_size);
 522   gold_assert(got_pov - got_view == got_size);
 523
 524   of->write_output_view(offset, oview_size, oview);
 525   of->write_output_view(got_file_offset, got_size, got_view);
 526 }
 527
 528 // Create a PLT entry for a global symbol.
 529
 530 void
 531 Target_x86_64::make_plt_entry(Symbol_table* symtab, Layout* layout,
 532                               Symbol* gsym)
 533 {
 534   if (gsym->has_plt_offset())
 535     return;
 536
 537   if (this->plt_ == NULL)
 538     {
 539       // Create the GOT sections first.
 540       this->got_section(symtab, layout);
 541
 542       this->plt_ = new Output_data_plt_x86_64(layout, this->got_plt_);
 543       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 544                                       (elfcpp::SHF_ALLOC
 545                                        | elfcpp::SHF_EXECINSTR),
 546                                       this->plt_);
 547     }
 548
 549   this->plt_->add_entry(gsym);
 550 }
 551
 552 // Handle a relocation against a non-function symbol defined in a
 553 // dynamic object.  The traditional way to handle this is to generate
 554 // a COPY relocation to copy the variable at runtime from the shared
 555 // object into the executable's data segment.  However, this is
 556 // undesirable in general, as if the size of the object changes in the
 557 // dynamic object, the executable will no longer work correctly.  If
 558 // this relocation is in a writable section, then we can create a
 559 // dynamic reloc and the dynamic linker will resolve it to the correct
 560 // address at runtime.  However, we do not want do that if the
 561 // relocation is in a read-only section, as it would prevent the
 562 // readonly segment from being shared.  And if we have to eventually
 563 // generate a COPY reloc, then any dynamic relocations will be
 564 // useless.  So this means that if this is a writable section, we need
 565 // to save the relocation until we see whether we have to create a
 566 // COPY relocation for this symbol for any other relocation.
 567
 568 void
 569 Target_x86_64::copy_reloc(const General_options* options,
 570                           Symbol_table* symtab,
 571                           Layout* layout,
 572                           Sized_relobj<64, false>* object,
 573                           unsigned int data_shndx, Symbol* gsym,
 574                           const elfcpp::Rela<64, false>& rela)
 575 {
 576   Sized_symbol<64>* ssym;
 577   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(64) (gsym
 578                                                         SELECT_SIZE(64));
 579
 580   if (!Copy_relocs<64, false>::need_copy_reloc(options, object,
 581                                                data_shndx, ssym))
 582     {
 583       // So far we do not need a COPY reloc.  Save this relocation.
 584       // If it turns out that we never need a COPY reloc for this
 585       // symbol, then we will emit the relocation.
 586       if (this->copy_relocs_ == NULL)
 587         this->copy_relocs_ = new Copy_relocs<64, false>();
 588       this->copy_relocs_->save(ssym, object, data_shndx, rela);
 589     }
 590   else
 591     {
 592       // Allocate space for this symbol in the .bss section.
 593
 594       elfcpp::Elf_types<64>::Elf_WXword symsize = ssym->symsize();
 595
 596       // There is no defined way to determine the required alignment
 597       // of the symbol.  We pick the alignment based on the size.  We
 598       // set an arbitrary maximum of 256.
 599       unsigned int align;
 600       for (align = 1; align < 512; align <<= 1)
 601         if ((symsize & align) != 0)
 602           break;
 603
 604       if (this->dynbss_ == NULL)
 605         {
 606           this->dynbss_ = new Output_data_space(align);
 607           layout->add_output_section_data(".bss",
 608                                           elfcpp::SHT_NOBITS,
 609                                           (elfcpp::SHF_ALLOC
 610                                            | elfcpp::SHF_WRITE),
 611                                           this->dynbss_);
 612         }
 613
 614       Output_data_space* dynbss = this->dynbss_;
 615
 616       if (align > dynbss->addralign())
 617         dynbss->set_space_alignment(align);
 618
 619       off_t dynbss_size = dynbss->data_size();
 620       dynbss_size = align_address(dynbss_size, align);
 621       off_t offset = dynbss_size;
 622       dynbss->set_space_size(dynbss_size + symsize);
 623
 624       // Define the symbol in the .dynbss section.
 625       symtab->define_in_output_data(this, ssym->name(), ssym->version(),
 626                                     dynbss, offset, symsize, ssym->type(),
 627                                     ssym->binding(), ssym->visibility(),
 628                                     ssym->nonvis(), false, false);
 629
 630       // Add the COPY reloc.
 631       ssym->set_needs_dynsym_entry();
 632       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
 633       rela_dyn->add_global(ssym, elfcpp::R_X86_64_COPY, dynbss, offset, 0);
 634     }
 635 }
 636
 637
 638 // Optimize the TLS relocation type based on what we know about the
 639 // symbol.  IS_FINAL is true if the final address of this symbol is
 640 // known at link time.
 641
 642 tls::Tls_optimization
 643 Target_x86_64::optimize_tls_reloc(bool is_final, int r_type)
 644 {
 645   // If we are generating a shared library, then we can't do anything
 646   // in the linker.
 647   if (parameters->output_is_shared())
 648     return tls::TLSOPT_NONE;
 649
 650   switch (r_type)
 651     {
 652     case elfcpp::R_X86_64_TLSGD:
 653     case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 654     case elfcpp::R_X86_64_TLSDESC_CALL:
 655       // These are General-Dynamic which permits fully general TLS
 656       // access.  Since we know that we are generating an executable,
 657       // we can convert this to Initial-Exec.  If we also know that
 658       // this is a local symbol, we can further switch to Local-Exec.
 659       if (is_final)
 660         return tls::TLSOPT_TO_LE;
 661       return tls::TLSOPT_TO_IE;
 662
 663     case elfcpp::R_X86_64_TLSLD:
 664       // This is Local-Dynamic, which refers to a local symbol in the
 665       // dynamic TLS block.  Since we know that we generating an
 666       // executable, we can switch to Local-Exec.
 667       return tls::TLSOPT_TO_LE;
 668
 669     case elfcpp::R_X86_64_DTPOFF32:
 670     case elfcpp::R_X86_64_DTPOFF64:
 671       // Another Local-Dynamic reloc.
 672       return tls::TLSOPT_TO_LE;
 673
 674     case elfcpp::R_X86_64_GOTTPOFF:
 675       // These are Initial-Exec relocs which get the thread offset
 676       // from the GOT.  If we know that we are linking against the
 677       // local symbol, we can switch to Local-Exec, which links the
 678       // thread offset into the instruction.
 679       if (is_final)
 680         return tls::TLSOPT_TO_LE;
 681       return tls::TLSOPT_NONE;
 682
 683     case elfcpp::R_X86_64_TPOFF32:
 684       // When we already have Local-Exec, there is nothing further we
 685       // can do.
 686       return tls::TLSOPT_NONE;
 687
 688     default:
 689       gold_unreachable();
 690     }
 691 }
 692
 693 // Report an unsupported relocation against a local symbol.
 694
 695 void
 696 Target_x86_64::Scan::unsupported_reloc_local(Sized_relobj<64, false>* object,
 697                                              unsigned int r_type)
 698 {
 699   gold_error(_("%s: unsupported reloc %u against local symbol"),
 700              object->name().c_str(), r_type);
 701 }
 702
 703 // Scan a relocation for a local symbol.
 704
 705 inline void
 706 Target_x86_64::Scan::local(const General_options&,
 707                            Symbol_table* symtab,
 708                            Layout* layout,
 709                            Target_x86_64* target,
 710                            Sized_relobj<64, false>* object,
 711                            unsigned int data_shndx,
 712                            const elfcpp::Rela<64, false>& reloc,
 713                            unsigned int r_type,
 714                            const elfcpp::Sym<64, false>&)
 715 {
 716   switch (r_type)
 717     {
 718     case elfcpp::R_X86_64_NONE:
 719     case elfcpp::R_386_GNU_VTINHERIT:
 720     case elfcpp::R_386_GNU_VTENTRY:
 721       break;
 722
 723     case elfcpp::R_X86_64_64:
 724     case elfcpp::R_X86_64_32:
 725     case elfcpp::R_X86_64_32S:
 726     case elfcpp::R_X86_64_16:
 727     case elfcpp::R_X86_64_8:
 728       // FIXME: If we are generating a shared object we need to copy
 729       // this relocation into the object.
 730       gold_assert(!parameters->output_is_shared());
 731       break;
 732
 733     case elfcpp::R_X86_64_PC64:
 734     case elfcpp::R_X86_64_PC32:
 735     case elfcpp::R_X86_64_PC16:
 736     case elfcpp::R_X86_64_PC8:
 737       break;
 738
 739     case elfcpp::R_X86_64_GOTPC32:  // TODO(csilvers): correct?
 740     case elfcpp::R_X86_64_GOTOFF64:
 741     case elfcpp::R_X86_64_GOTPC64:  // TODO(csilvers): correct?
 742     case elfcpp::R_X86_64_PLTOFF64:  // TODO(csilvers): correct?
 743       // We need a GOT section.
 744       target->got_section(symtab, layout);
 745       break;
 746
 747     case elfcpp::R_X86_64_GOT64:
 748     case elfcpp::R_X86_64_GOT32:
 749     case elfcpp::R_X86_64_GOTPCREL64:
 750     case elfcpp::R_X86_64_GOTPCREL:
 751       {
 752         // The symbol requires a GOT entry.
 753         Output_data_got<64, false>* got = target->got_section(symtab, layout);
 754         unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 755         if (got->add_local(object, r_sym))
 756           {
 757             // If we are generating a shared object, we need to add a
 758             // dynamic RELATIVE relocation for this symbol.
 759             if (parameters->output_is_shared())
 760               {
 761                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 762                 rela_dyn->add_local(object, 0, elfcpp::R_X86_64_RELATIVE,
 763                                     data_shndx, reloc.get_r_offset(), 0);
 764               }
 765           }
 766       }
 767       break;
 768
 769     case elfcpp::R_X86_64_COPY:
 770     case elfcpp::R_X86_64_GLOB_DAT:
 771     case elfcpp::R_X86_64_JUMP_SLOT:
 772     case elfcpp::R_X86_64_RELATIVE:
 773       // These are outstanding tls relocs, which are unexpected when linking
 774     case elfcpp::R_X86_64_TPOFF64:
 775     case elfcpp::R_X86_64_DTPMOD64:
 776     case elfcpp::R_X86_64_TLSDESC:
 777       gold_error(_("%s: unexpected reloc %u in object file"),
 778                  object->name().c_str(), r_type);
 779       break;
 780
 781       // These are initial tls relocs, which are expected when linking
 782     case elfcpp::R_X86_64_TLSGD:
 783     case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 784     case elfcpp::R_X86_64_TLSDESC_CALL:
 785     case elfcpp::R_X86_64_TLSLD:
 786     case elfcpp::R_X86_64_GOTTPOFF:
 787     case elfcpp::R_X86_64_TPOFF32:
 788     case elfcpp::R_X86_64_DTPOFF32:
 789     case elfcpp::R_X86_64_DTPOFF64:
 790       {
 791         bool output_is_shared = parameters->output_is_shared();
 792         const tls::Tls_optimization optimized_type
 793             = Target_x86_64::optimize_tls_reloc(!output_is_shared, r_type);
 794         switch (r_type)
 795           {
 796           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
 797             // FIXME: If generating a shared object, we need to copy
 798             // this relocation into the object.
 799             gold_assert(!output_is_shared);
 800             break;
 801
 802           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
 803             // FIXME: If not relaxing to LE, we need to generate a
 804             // TPOFF64 reloc.
 805             if (optimized_type != tls::TLSOPT_TO_LE)
 806               unsupported_reloc_local(object, r_type);
 807             break;
 808
 809           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
 810           case elfcpp::R_X86_64_DTPOFF32:
 811           case elfcpp::R_X86_64_DTPOFF64:
 812             // FIXME: If not relaxing to LE, we need to generate a
 813             // DTPMOD64 reloc.
 814             if (optimized_type != tls::TLSOPT_TO_LE)
 815               unsupported_reloc_local(object, r_type);
 816             break;
 817
 818
 819           case elfcpp::R_X86_64_TLSGD:       // General-dynamic
 820           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 821           case elfcpp::R_X86_64_TLSDESC_CALL:
 822             // FIXME: If not relaxing to LE, we need to generate
 823             // DTPMOD64 and DTPOFF64 relocs.
 824             if (optimized_type != tls::TLSOPT_TO_LE)
 825               unsupported_reloc_local(object, r_type);
 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_PLT32:
 836     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
 837     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
 838     default:
 839       gold_error(_("%s: unsupported reloc %u against local symbol"),
 840                  object->name().c_str(), r_type);
 841       break;
 842     }
 843 }
 844
 845
 846 // Report an unsupported relocation against a global symbol.
 847
 848 void
 849 Target_x86_64::Scan::unsupported_reloc_global(Sized_relobj<64, false>* object,
 850                                               unsigned int r_type,
 851                                               Symbol* gsym)
 852 {
 853   gold_error(_("%s: unsupported reloc %u against global symbol %s"),
 854              object->name().c_str(), r_type, gsym->name());
 855 }
 856
 857 // Scan a relocation for a global symbol.
 858
 859 inline void
 860 Target_x86_64::Scan::global(const General_options& options,
 861                             Symbol_table* symtab,
 862                             Layout* layout,
 863                             Target_x86_64* target,
 864                             Sized_relobj<64, false>* object,
 865                             unsigned int data_shndx,
 866                             const elfcpp::Rela<64, false>& reloc,
 867                             unsigned int r_type,
 868                             Symbol* gsym)
 869 {
 870   switch (r_type)
 871     {
 872     case elfcpp::R_X86_64_NONE:
 873     case elfcpp::R_386_GNU_VTINHERIT:
 874     case elfcpp::R_386_GNU_VTENTRY:
 875       break;
 876
 877     case elfcpp::R_X86_64_64:
 878     case elfcpp::R_X86_64_PC64:
 879     case elfcpp::R_X86_64_32:
 880     case elfcpp::R_X86_64_32S:
 881     case elfcpp::R_X86_64_PC32:
 882     case elfcpp::R_X86_64_16:
 883     case elfcpp::R_X86_64_PC16:
 884     case elfcpp::R_X86_64_8:
 885     case elfcpp::R_X86_64_PC8:
 886       // FIXME: If we are generating a shared object we may need to
 887       // copy this relocation into the object.  If this symbol is
 888       // defined in a shared object, we may need to copy this
 889       // relocation in order to avoid a COPY relocation.
 890       gold_assert(!parameters->output_is_shared());
 891
 892       if (gsym->is_from_dynobj())
 893         {
 894           // This symbol is defined in a dynamic object.  If it is a
 895           // function, we make a PLT entry.  Otherwise we need to
 896           // either generate a COPY reloc or copy this reloc.
 897           if (gsym->type() == elfcpp::STT_FUNC)
 898             {
 899               target->make_plt_entry(symtab, layout, gsym);
 900
 901               // If this is not a PC relative reference, then we may
 902               // be taking the address of the function.  In that case
 903               // we need to set the entry in the dynamic symbol table
 904               // to the address of the PLT entry.
 905               if (r_type != elfcpp::R_X86_64_PC64
 906                   && r_type != elfcpp::R_X86_64_PC32
 907                   && r_type != elfcpp::R_X86_64_PC16
 908                   && r_type != elfcpp::R_X86_64_PC8)
 909                 gsym->set_needs_dynsym_value();
 910             }
 911           else
 912             target->copy_reloc(&options, symtab, layout, object, data_shndx,
 913                                gsym, reloc);
 914         }
 915
 916       break;
 917
 918     case elfcpp::R_X86_64_GOT64:
 919     case elfcpp::R_X86_64_GOT32:
 920     case elfcpp::R_X86_64_GOTPCREL64:
 921     case elfcpp::R_X86_64_GOTPCREL:
 922     case elfcpp::R_X86_64_GOTPLT64:
 923       {
 924         // The symbol requires a GOT entry.
 925         Output_data_got<64, false>* got = target->got_section(symtab, layout);
 926         if (got->add_global(gsym))
 927           {
 928             // If this symbol is not fully resolved, we need to add a
 929             // dynamic relocation for it.
 930             if (!gsym->final_value_is_known())
 931               {
 932                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 933                 rela_dyn->add_global(gsym, elfcpp::R_X86_64_GLOB_DAT, got,
 934                                      gsym->got_offset(), 0);
 935               }
 936           }
 937       }
 938       break;
 939
 940     case elfcpp::R_X86_64_PLT32:
 941       // If the symbol is fully resolved, this is just a PC32 reloc.
 942       // Otherwise we need a PLT entry.
 943       if (gsym->final_value_is_known())
 944         break;
 945       target->make_plt_entry(symtab, layout, gsym);
 946       break;
 947
 948     case elfcpp::R_X86_64_GOTPC32:  // TODO(csilvers): correct?
 949     case elfcpp::R_X86_64_GOTOFF64:
 950     case elfcpp::R_X86_64_GOTPC64:  // TODO(csilvers): correct?
 951     case elfcpp::R_X86_64_PLTOFF64:  // TODO(csilvers): correct?
 952       // We need a GOT section.
 953       target->got_section(symtab, layout);
 954       break;
 955
 956     case elfcpp::R_X86_64_COPY:
 957     case elfcpp::R_X86_64_GLOB_DAT:
 958     case elfcpp::R_X86_64_JUMP_SLOT:
 959     case elfcpp::R_X86_64_RELATIVE:
 960       // These are outstanding tls relocs, which are unexpected when linking
 961     case elfcpp::R_X86_64_TPOFF64:
 962     case elfcpp::R_X86_64_DTPMOD64:
 963     case elfcpp::R_X86_64_TLSDESC:
 964       gold_error(_("%s: unexpected reloc %u in object file"),
 965                  object->name().c_str(), r_type);
 966       break;
 967
 968       // These are initial tls relocs, which are expected for global()
 969     case elfcpp::R_X86_64_TLSGD:
 970     case elfcpp::R_X86_64_TLSLD:
 971     case elfcpp::R_X86_64_GOTTPOFF:
 972     case elfcpp::R_X86_64_TPOFF32:
 973     case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 974     case elfcpp::R_X86_64_TLSDESC_CALL:
 975     case elfcpp::R_X86_64_DTPOFF32:
 976     case elfcpp::R_X86_64_DTPOFF64:
 977       {
 978         const bool is_final = gsym->final_value_is_known();
 979         const tls::Tls_optimization optimized_type
 980             = Target_x86_64::optimize_tls_reloc(is_final, r_type);
 981         switch (r_type)
 982           {
 983           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
 984             // FIXME: If generating a shared object, we need to copy
 985             // this relocation into the object.
 986             gold_assert(is_final);
 987             break;
 988
 989           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
 990             // FIXME: If not relaxing to LE, we need to generate a
 991             // TPOFF64 reloc.
 992             if (optimized_type != tls::TLSOPT_TO_LE)
 993               unsupported_reloc_global(object, r_type, gsym);
 994             break;
 995
 996           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
 997           case elfcpp::R_X86_64_DTPOFF32:
 998           case elfcpp::R_X86_64_DTPOFF64:
 999             // FIXME: If not relaxing to LE, we need to generate a
1000             // DTPMOD64 reloc.
1001             if (optimized_type != tls::TLSOPT_TO_LE)
1002               unsupported_reloc_global(object, r_type, gsym);
1003             break;
1004
1005
1006           case elfcpp::R_X86_64_TLSGD:       // General-dynamic
1007           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
1008           case elfcpp::R_X86_64_TLSDESC_CALL:
1009             // FIXME: If not relaxing to LE, we need to generate
1010             // DTPMOD64 and DTPOFF64, or TLSDESC, relocs.
1011             if (optimized_type != tls::TLSOPT_TO_LE)
1012               unsupported_reloc_global(object, r_type, gsym);
1013             break;
1014
1015           default:
1016             gold_unreachable();
1017           }
1018       }
1019       break;
1020     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
1021     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
1022     default:
1023       gold_error(_("%s: unsupported reloc %u against global symbol %s"),
1024                  object->name().c_str(), r_type, gsym->name());
1025       break;
1026     }
1027 }
1028
1029 // Scan relocations for a section.
1030
1031 void
1032 Target_x86_64::scan_relocs(const General_options& options,
1033                            Symbol_table* symtab,
1034                            Layout* layout,
1035                            Sized_relobj<64, false>* object,
1036                            unsigned int data_shndx,
1037                            unsigned int sh_type,
1038                            const unsigned char* prelocs,
1039                            size_t reloc_count,
1040                            size_t local_symbol_count,
1041                            const unsigned char* plocal_symbols,
1042                            Symbol** global_symbols)
1043 {
1044   if (sh_type == elfcpp::SHT_REL)
1045     {
1046       gold_error(_("%s: unsupported REL reloc section"),
1047                  object->name().c_str());
1048       return;
1049     }
1050
1051   gold::scan_relocs<64, false, Target_x86_64, elfcpp::SHT_RELA,
1052       Target_x86_64::Scan>(
1053     options,
1054     symtab,
1055     layout,
1056     this,
1057     object,
1058     data_shndx,
1059     prelocs,
1060     reloc_count,
1061     local_symbol_count,
1062     plocal_symbols,
1063     global_symbols);
1064 }
1065
1066 // Finalize the sections.
1067
1068 void
1069 Target_x86_64::do_finalize_sections(Layout* layout)
1070 {
1071   // Fill in some more dynamic tags.
1072   Output_data_dynamic* const odyn = layout->dynamic_data();
1073   if (odyn != NULL)
1074     {
1075       if (this->got_plt_ != NULL)
1076         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1077
1078       if (this->plt_ != NULL)
1079         {
1080           const Output_data* od = this->plt_->rel_plt();
1081           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1082           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1083           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_RELA);
1084         }
1085
1086       if (this->rela_dyn_ != NULL)
1087         {
1088           const Output_data* od = this->rela_dyn_;
1089           odyn->add_section_address(elfcpp::DT_RELA, od);
1090           odyn->add_section_size(elfcpp::DT_RELASZ, od);
1091           odyn->add_constant(elfcpp::DT_RELAENT,
1092                              elfcpp::Elf_sizes<64>::rela_size);
1093         }
1094
1095       if (!parameters->output_is_shared())
1096         {
1097           // The value of the DT_DEBUG tag is filled in by the dynamic
1098           // linker at run time, and used by the debugger.
1099           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1100         }
1101     }
1102
1103   // Emit any relocs we saved in an attempt to avoid generating COPY
1104   // relocs.
1105   if (this->copy_relocs_ == NULL)
1106     return;
1107   if (this->copy_relocs_->any_to_emit())
1108     {
1109       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
1110       this->copy_relocs_->emit(rela_dyn);
1111     }
1112   delete this->copy_relocs_;
1113   this->copy_relocs_ = NULL;
1114 }
1115
1116 // Perform a relocation.
1117
1118 inline bool
1119 Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo,
1120                                   Target_x86_64* target,
1121                                   size_t relnum,
1122                                   const elfcpp::Rela<64, false>& rela,
1123                                   unsigned int r_type,
1124                                   const Sized_symbol<64>* gsym,
1125                                   const Symbol_value<64>* psymval,
1126                                   unsigned char* view,
1127                                   elfcpp::Elf_types<64>::Elf_Addr address,
1128                                   off_t view_size)
1129 {
1130   if (this->skip_call_tls_get_addr_)
1131     {
1132       if (r_type != elfcpp::R_X86_64_PLT32
1133           || gsym == NULL
1134           || strcmp(gsym->name(), "__tls_get_addr") != 0)
1135         {
1136           gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1137                                  _("missing expected TLS relocation"));
1138         }
1139       else
1140         {
1141           this->skip_call_tls_get_addr_ = false;
1142           return false;
1143         }
1144     }
1145
1146   // Pick the value to use for symbols defined in shared objects.
1147   Symbol_value<64> symval;
1148   if (gsym != NULL && gsym->is_from_dynobj() && gsym->has_plt_offset())
1149     {
1150       symval.set_output_value(target->plt_section()->address()
1151                               + gsym->plt_offset());
1152       psymval = &symval;
1153     }
1154
1155   const Sized_relobj<64, false>* object = relinfo->object;
1156   const elfcpp::Elf_Xword addend = rela.get_r_addend();
1157
1158   // Get the GOT offset if needed.
1159   bool have_got_offset = false;
1160   unsigned int got_offset = 0;
1161   switch (r_type)
1162     {
1163     case elfcpp::R_X86_64_GOT32:
1164     case elfcpp::R_X86_64_GOT64:
1165     case elfcpp::R_X86_64_GOTPLT64:
1166     case elfcpp::R_X86_64_GOTPCREL:
1167     case elfcpp::R_X86_64_GOTPCREL64:
1168       if (gsym != NULL)
1169         {
1170           gold_assert(gsym->has_got_offset());
1171           got_offset = gsym->got_offset();
1172         }
1173       else
1174         {
1175           unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1176           got_offset = object->local_got_offset(r_sym);
1177         }
1178       have_got_offset = true;
1179       break;
1180
1181     default:
1182       break;
1183     }
1184
1185   switch (r_type)
1186     {
1187     case elfcpp::R_X86_64_NONE:
1188     case elfcpp::R_386_GNU_VTINHERIT:
1189     case elfcpp::R_386_GNU_VTENTRY:
1190       break;
1191
1192     case elfcpp::R_X86_64_64:
1193       Relocate_functions<64, false>::rela64(view, object, psymval, addend);
1194       break;
1195
1196     case elfcpp::R_X86_64_PC64:
1197       Relocate_functions<64, false>::pcrela64(view, object, psymval, addend,
1198                                               address);
1199       break;
1200
1201     case elfcpp::R_X86_64_32:
1202       // FIXME: we need to verify that value + addend fits into 32 bits:
1203       //    uint64_t x = value + addend;
1204       //    x == static_cast<uint64_t>(static_cast<uint32_t>(x))
1205       // Likewise for other <=32-bit relocations (but see R_X86_64_32S).
1206       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1207       break;
1208
1209     case elfcpp::R_X86_64_32S:
1210       // FIXME: we need to verify that value + addend fits into 32 bits:
1211       //    int64_t x = value + addend;   // note this quantity is signed!
1212       //    x == static_cast<int64_t>(static_cast<int32_t>(x))
1213       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1214       break;
1215
1216     case elfcpp::R_X86_64_PC32:
1217       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1218                                               address);
1219       break;
1220
1221     case elfcpp::R_X86_64_16:
1222       Relocate_functions<64, false>::rela16(view, object, psymval, addend);
1223       break;
1224
1225     case elfcpp::R_X86_64_PC16:
1226       Relocate_functions<64, false>::pcrela16(view, object, psymval, addend,
1227                                               address);
1228       break;
1229
1230     case elfcpp::R_X86_64_8:
1231       Relocate_functions<64, false>::rela8(view, object, psymval, addend);
1232       break;
1233
1234     case elfcpp::R_X86_64_PC8:
1235       Relocate_functions<64, false>::pcrela8(view, object, psymval, addend,
1236                                              address);
1237       break;
1238
1239     case elfcpp::R_X86_64_PLT32:
1240       gold_assert(gsym->has_plt_offset()
1241                   || gsym->final_value_is_known());
1242       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1243                                               address);
1244       break;
1245
1246     case elfcpp::R_X86_64_GOT32:
1247       gold_assert(have_got_offset);
1248       Relocate_functions<64, false>::rela32(view, got_offset, addend);
1249       break;
1250
1251     case elfcpp::R_X86_64_GOTPC32:
1252       {
1253         gold_assert(gsym);
1254         elfcpp::Elf_types<64>::Elf_Addr value;
1255         value = target->got_section(NULL, NULL)->address();
1256         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1257       }
1258       break;
1259
1260     case elfcpp::R_X86_64_GOT64:
1261       // The ABI doc says "Like GOT64, but indicates a PLT entry is needed."
1262       // Since we always add a PLT entry, this is equivalent.
1263     case elfcpp::R_X86_64_GOTPLT64:  // TODO(csilvers): correct?
1264       gold_assert(have_got_offset);
1265       Relocate_functions<64, false>::rela64(view, got_offset, addend);
1266       break;
1267
1268     case elfcpp::R_X86_64_GOTPC64:
1269       {
1270         gold_assert(gsym);
1271         elfcpp::Elf_types<64>::Elf_Addr value;
1272         value = target->got_section(NULL, NULL)->address();
1273         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1274       }
1275       break;
1276
1277     case elfcpp::R_X86_64_GOTOFF64:
1278       {
1279         elfcpp::Elf_types<64>::Elf_Addr value;
1280         value = (psymval->value(object, 0)
1281                  - target->got_section(NULL, NULL)->address());
1282         Relocate_functions<64, false>::rela64(view, value, addend);
1283       }
1284       break;
1285
1286     case elfcpp::R_X86_64_GOTPCREL:
1287       {
1288         gold_assert(have_got_offset);
1289         elfcpp::Elf_types<64>::Elf_Addr value;
1290         value = target->got_section(NULL, NULL)->address() + got_offset;
1291         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1292       }
1293       break;
1294
1295     case elfcpp::R_X86_64_GOTPCREL64:
1296       {
1297         gold_assert(have_got_offset);
1298         elfcpp::Elf_types<64>::Elf_Addr value;
1299         value = target->got_section(NULL, NULL)->address() + got_offset;
1300         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1301       }
1302       break;
1303
1304     case elfcpp::R_X86_64_COPY:
1305     case elfcpp::R_X86_64_GLOB_DAT:
1306     case elfcpp::R_X86_64_JUMP_SLOT:
1307     case elfcpp::R_X86_64_RELATIVE:
1308       // These are outstanding tls relocs, which are unexpected when linking
1309     case elfcpp::R_X86_64_TPOFF64:
1310     case elfcpp::R_X86_64_DTPMOD64:
1311     case elfcpp::R_X86_64_TLSDESC:
1312       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1313                              _("unexpected reloc %u in object file"),
1314                              r_type);
1315       break;
1316
1317       // These are initial tls relocs, which are expected when linking
1318     case elfcpp::R_X86_64_TLSGD:
1319     case elfcpp::R_X86_64_TLSLD:
1320     case elfcpp::R_X86_64_GOTTPOFF:
1321     case elfcpp::R_X86_64_TPOFF32:
1322     case elfcpp::R_X86_64_GOTPC32_TLSDESC:
1323     case elfcpp::R_X86_64_TLSDESC_CALL:
1324     case elfcpp::R_X86_64_DTPOFF32:
1325     case elfcpp::R_X86_64_DTPOFF64:
1326       this->relocate_tls(relinfo, relnum, rela, r_type, gsym, psymval, view,
1327                          address, view_size);
1328       break;
1329
1330     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
1331     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
1332     case elfcpp::R_X86_64_PLTOFF64:  // TODO(csilvers): implement me!
1333     default:
1334       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1335                              _("unsupported reloc %u"),
1336                              r_type);
1337       break;
1338     }
1339
1340   return true;
1341 }
1342
1343 // Perform a TLS relocation.
1344
1345 inline void
1346 Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo,
1347                                       size_t relnum,
1348                                       const elfcpp::Rela<64, false>& rela,
1349                                       unsigned int r_type,
1350                                       const Sized_symbol<64>* gsym,
1351                                       const Symbol_value<64>* psymval,
1352                                       unsigned char* view,
1353                                       elfcpp::Elf_types<64>::Elf_Addr,
1354                                       off_t view_size)
1355 {
1356   Output_segment* tls_segment = relinfo->layout->tls_segment();
1357   if (tls_segment == NULL)
1358     {
1359       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1360                              _("TLS reloc but no TLS segment"));
1361       return;
1362     }
1363
1364   elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0);
1365
1366   const bool is_final = (gsym == NULL
1367                          ? !parameters->output_is_shared()
1368                          : gsym->final_value_is_known());
1369   const tls::Tls_optimization optimized_type
1370       = Target_x86_64::optimize_tls_reloc(is_final, r_type);
1371   switch (r_type)
1372     {
1373     case elfcpp::R_X86_64_TPOFF32:   // Local-exec reloc
1374       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1375       Relocate_functions<64, false>::rel32(view, value);
1376       break;
1377
1378     case elfcpp::R_X86_64_GOTTPOFF:  // Initial-exec reloc
1379       if (optimized_type == tls::TLSOPT_TO_LE)
1380         {
1381           Target_x86_64::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1382                                                 rela, r_type, value, view,
1383                                                 view_size);
1384           break;
1385         }
1386       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1387                              _("unsupported reloc type %u"),
1388                              r_type);
1389       break;
1390
1391     case elfcpp::R_X86_64_TLSGD:
1392     case elfcpp::R_X86_64_GOTPC32_TLSDESC:
1393     case elfcpp::R_X86_64_TLSDESC_CALL:
1394       if (optimized_type == tls::TLSOPT_TO_LE)
1395         {
1396           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1397                              rela, r_type, value, view,
1398                              view_size);
1399           break;
1400         }
1401       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1402                              _("unsupported reloc %u"), r_type);
1403       break;
1404
1405     case elfcpp::R_X86_64_TLSLD:
1406       if (optimized_type == tls::TLSOPT_TO_LE)
1407         {
1408           this->tls_ld_to_le(relinfo, relnum, tls_segment, rela, r_type,
1409                              value, view, view_size);
1410           break;
1411         }
1412       gold_error_at_location(relinfo, relnum, rela.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>& rela,
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   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1454   tls::check_range(relinfo, relnum, rela.get_r_offset(), 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>& rela,
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   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4);
1508   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12);
1509
1510   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1511                  (memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0));
1512   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1513                  (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0));
1514
1515   memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x8d\x80\0\0\0\0", 16);
1516
1517   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1518   Relocate_functions<64, false>::rela32(view + 8, value, 0);
1519
1520   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1521   // We can skip it.
1522   this->skip_call_tls_get_addr_ = true;
1523 }
1524
1525 inline void
1526 Target_x86_64::Relocate::tls_ld_to_le(const Relocate_info<64, false>* relinfo,
1527                                       size_t relnum,
1528                                       Output_segment*,
1529                                       const elfcpp::Rela<64, false>& rela,
1530                                       unsigned int,
1531                                       elfcpp::Elf_types<64>::Elf_Addr,
1532                                       unsigned char* view,
1533                                       off_t view_size)
1534 {
1535   // leaq foo@tlsld(%rip),%rdi; call __tls_get_addr@plt;
1536   // ... leq foo@dtpoff(%rax),%reg
1537   // ==> .word 0x6666; .byte 0x66; movq %fs:0,%rax ... leaq x@tpoff(%rax),%rdx
1538
1539   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1540   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 9);
1541
1542   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1543                  view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x3d);
1544
1545   tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[4] == 0xe8);
1546
1547   memcpy(view - 3, "\x66\x66\x66\x64\x48\x8b\x04\x25\0\0\0\0", 12);
1548
1549   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1550   // We can skip it.
1551   this->skip_call_tls_get_addr_ = true;
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.