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
  48 namespace
  49 {
  50
  51 using namespace gold;
  52
  53 class Output_data_plt_x86_64;
  54
  55 // The x86_64 target class.
  56 // See the ABI at http://www.x86-64.org/documentation/abi.pdf
  57
  58 class Target_x86_64 : public Sized_target<64, false>
  59 {
  60  public:
  61   // In the x86_64 ABI (p 68), it says "The AMD64 ABI architectures
  62   // uses only Elf64_Rela relocation entries with explicit addends."
  63   typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
  64
  65   Target_x86_64()
  66     : Sized_target<64, false>(&x86_64_info),
  67       got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
  68       copy_relocs_(NULL), dynbss_(NULL)
  69   { }
  70
  71   // Scan the relocations to look for symbol adjustments.
  72   void
  73   scan_relocs(const General_options& options,
  74               Symbol_table* symtab,
  75               Layout* layout,
  76               Sized_relobj<64, false>* object,
  77               unsigned int data_shndx,
  78               unsigned int sh_type,
  79               const unsigned char* prelocs,
  80               size_t reloc_count,
  81               size_t local_symbol_count,
  82               const unsigned char* plocal_symbols,
  83               Symbol** global_symbols);
  84
  85   // Finalize the sections.
  86   void
  87   do_finalize_sections(Layout*);
  88
  89   // Return the value to use for a dynamic which requires special
  90   // treatment.
  91   uint64_t
  92   do_dynsym_value(const Symbol*) const;
  93
  94   // Relocate a section.
  95   void
  96   relocate_section(const Relocate_info<64, false>*,
  97                    unsigned int sh_type,
  98                    const unsigned char* prelocs,
  99                    size_t reloc_count,
 100                    unsigned char* view,
 101                    elfcpp::Elf_types<64>::Elf_Addr view_address,
 102                    off_t view_size);
 103
 104   // Return a string used to fill a code section with nops.
 105   std::string
 106   do_code_fill(off_t length);
 107
 108  private:
 109   // The class which scans relocations.
 110   struct Scan
 111   {
 112     inline void
 113     local(const General_options& options, Symbol_table* symtab,
 114           Layout* layout, Target_x86_64* target,
 115           Sized_relobj<64, false>* object,
 116           unsigned int data_shndx,
 117           const elfcpp::Rela<64, false>& reloc, unsigned int r_type,
 118           const elfcpp::Sym<64, false>& lsym);
 119
 120     inline void
 121     global(const General_options& options, Symbol_table* symtab,
 122            Layout* layout, Target_x86_64* target,
 123            Sized_relobj<64, false>* object,
 124            unsigned int data_shndx,
 125            const elfcpp::Rela<64, false>& reloc, unsigned int r_type,
 126            Symbol* gsym);
 127   };
 128
 129   // The class which implements relocation.
 130   class Relocate
 131   {
 132    public:
 133     Relocate()
 134       : skip_call_tls_get_addr_(false)
 135     { }
 136
 137     ~Relocate()
 138     {
 139       if (this->skip_call_tls_get_addr_)
 140         {
 141           // FIXME: This needs to specify the location somehow.
 142           fprintf(stderr, _("%s: missing expected TLS relocation\n"),
 143                   program_name);
 144           gold_exit(false);
 145         }
 146     }
 147
 148     // Do a relocation.  Return false if the caller should not issue
 149     // any warnings about this relocation.
 150     inline bool
 151     relocate(const Relocate_info<64, false>*, Target_x86_64*, size_t relnum,
 152              const elfcpp::Rela<64, false>&,
 153              unsigned int r_type, const Sized_symbol<64>*,
 154              const Symbol_value<64>*,
 155              unsigned char*, elfcpp::Elf_types<64>::Elf_Addr,
 156              off_t);
 157
 158    private:
 159     // Do a TLS relocation.
 160     inline void
 161     relocate_tls(const Relocate_info<64, false>*, 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, off_t);
 166
 167     // Do a TLS Initial-Exec to Local-Exec transition.
 168     static inline void
 169     tls_ie_to_le(const Relocate_info<64, false>*, size_t relnum,
 170                  Output_segment* tls_segment,
 171                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 172                  elfcpp::Elf_types<64>::Elf_Addr value,
 173                  unsigned char* view,
 174                  off_t view_size);
 175
 176     // Do a TLS Global-Dynamic to Local-Exec transition.
 177     inline void
 178     tls_gd_to_le(const Relocate_info<64, false>*, size_t relnum,
 179                  Output_segment* tls_segment,
 180                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 181                  elfcpp::Elf_types<64>::Elf_Addr value,
 182                  unsigned char* view,
 183                  off_t view_size);
 184
 185     // Check the range for a TLS relocation.
 186     static inline void
 187     check_range(const Relocate_info<64, false>*, size_t relnum,
 188                 const elfcpp::Rela<64, false>&, off_t, off_t);
 189
 190     // Check the validity of a TLS relocation.  This is like assert.
 191     static inline void
 192     check_tls(const Relocate_info<64, false>*, size_t relnum,
 193               const elfcpp::Rela<64, false>&, bool);
 194
 195     // This is set if we should skip the next reloc, which should be a
 196     // PLT32 reloc against ___tls_get_addr.
 197     bool skip_call_tls_get_addr_;
 198   };
 199
 200   // Adjust TLS relocation type based on the options and whether this
 201   // is a local symbol.
 202   static unsigned int
 203   optimize_tls_reloc(bool is_final, int r_type);
 204
 205   // Get the GOT section, creating it if necessary.
 206   Output_data_got<64, false>*
 207   got_section(Symbol_table*, Layout*);
 208
 209   // Create a PLT entry for a global symbol.
 210   void
 211   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 212
 213   // Get the PLT section.
 214   Output_data_plt_x86_64*
 215   plt_section() const
 216   {
 217     gold_assert(this->plt_ != NULL);
 218     return this->plt_;
 219   }
 220
 221   // Get the dynamic reloc section, creating it if necessary.
 222   Reloc_section*
 223   rel_dyn_section(Layout*);
 224
 225   // Copy a relocation against a global symbol.
 226   void
 227   copy_reloc(const General_options*, Symbol_table*, Layout*,
 228              Sized_relobj<64, false>*, unsigned int,
 229              Symbol*, const elfcpp::Rela<64, false>&);
 230
 231   // Information about this specific target which we pass to the
 232   // general Target structure.
 233   static const Target::Target_info x86_64_info;
 234
 235   // The GOT section.
 236   Output_data_got<64, false>* got_;
 237   // The PLT section.
 238   Output_data_plt_x86_64* plt_;
 239   // The GOT PLT section.
 240   Output_data_space* got_plt_;
 241   // The dynamic reloc section.
 242   Reloc_section* rel_dyn_;
 243   // Relocs saved to avoid a COPY reloc.
 244   Copy_relocs<64, false>* copy_relocs_;
 245   // Space for variables copied with a COPY reloc.
 246   Output_data_space* dynbss_;
 247 };
 248
 249 const Target::Target_info Target_x86_64::x86_64_info =
 250 {
 251   64,                   // size
 252   false,                // is_big_endian
 253   elfcpp::EM_X86_64,    // machine_code
 254   false,                // has_make_symbol
 255   false,                // has_resolve
 256   true,                 // has_code_fill
 257   "/lib/ld64.so.1",     // program interpreter
 258   0x400000,             // text_segment_address
 259   0x1000,               // abi_pagesize
 260   0x1000                // common_pagesize
 261 };
 262
 263 // Get the GOT section, creating it if necessary.
 264
 265 Output_data_got<64, false>*
 266 Target_x86_64::got_section(Symbol_table* symtab, Layout* layout)
 267 {
 268   if (this->got_ == NULL)
 269     {
 270       gold_assert(symtab != NULL && layout != NULL);
 271
 272       this->got_ = new Output_data_got<64, false>();
 273
 274       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 275                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 276                                       this->got_);
 277
 278       // The old GNU linker creates a .got.plt section.  We just
 279       // create another set of data in the .got section.  Note that we
 280       // always create a PLT if we create a GOT, although the PLT
 281       // might be empty.
 282       // TODO(csilvers): do we really need an alignment of 8?
 283       this->got_plt_ = new Output_data_space(8);
 284       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 285                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 286                                       this->got_plt_);
 287
 288       // The first three entries are reserved.
 289       this->got_plt_->set_space_size(3 * 8);
 290
 291       // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
 292       symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
 293                                     this->got_plt_,
 294                                     0, 0, elfcpp::STT_OBJECT,
 295                                     elfcpp::STB_LOCAL,
 296                                     elfcpp::STV_HIDDEN, 0,
 297                                     false, false);
 298     }
 299
 300   return this->got_;
 301 }
 302
 303 // Get the dynamic reloc section, creating it if necessary.
 304
 305 Target_x86_64::Reloc_section*
 306 Target_x86_64::rel_dyn_section(Layout* layout)
 307 {
 308   if (this->rel_dyn_ == NULL)
 309     {
 310       gold_assert(layout != NULL);
 311       this->rel_dyn_ = new Reloc_section();
 312       layout->add_output_section_data(".rela.dyn", elfcpp::SHT_RELA,
 313                                       elfcpp::SHF_ALLOC, this->rel_dyn_);
 314     }
 315   return this->rel_dyn_;
 316 }
 317
 318 // A class to handle the PLT data.
 319
 320 class Output_data_plt_x86_64 : public Output_section_data
 321 {
 322  public:
 323   typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
 324
 325   Output_data_plt_x86_64(Layout*, Output_data_space*);
 326
 327   // Add an entry to the PLT.
 328   void
 329   add_entry(Symbol* gsym);
 330
 331   // Return the .rel.plt section data.
 332   const Reloc_section*
 333   rel_plt() const
 334   { return this->rel_; }
 335
 336  protected:
 337   void
 338   do_adjust_output_section(Output_section* os);
 339
 340  private:
 341   // The size of an entry in the PLT.
 342   static const int plt_entry_size = 16;
 343
 344   // The first entry in the PLT.
 345   // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same
 346   // procedure linkage table for both programs and shared objects."
 347   static unsigned char first_plt_entry[plt_entry_size];
 348
 349   // Other entries in the PLT for an executable.
 350   static unsigned char plt_entry[plt_entry_size];
 351
 352   // Set the final size.
 353   void
 354   do_set_address(uint64_t, off_t)
 355   { this->set_data_size((this->count_ + 1) * plt_entry_size); }
 356
 357   // Write out the PLT data.
 358   void
 359   do_write(Output_file*);
 360
 361   // The reloc section.
 362   Reloc_section* rel_;
 363   // The .got.plt section.
 364   Output_data_space* got_plt_;
 365   // The number of PLT entries.
 366   unsigned int count_;
 367 };
 368
 369 // Create the PLT section.  The ordinary .got section is an argument,
 370 // since we need to refer to the start.  We also create our own .got
 371 // section just for PLT entries.
 372
 373 Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout,
 374                                                Output_data_space* got_plt)
 375     // TODO(csilvers): do we really need an alignment of 8?
 376   : Output_section_data(8), got_plt_(got_plt), count_(0)
 377 {
 378   this->rel_ = new Reloc_section();
 379   layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
 380                                   elfcpp::SHF_ALLOC, this->rel_);
 381 }
 382
 383 void
 384 Output_data_plt_x86_64::do_adjust_output_section(Output_section* os)
 385 {
 386   // UnixWare sets the entsize of .plt to 4, and so does the old GNU
 387   // linker, and so do we.
 388   os->set_entsize(4);
 389 }
 390
 391 // Add an entry to the PLT.
 392
 393 void
 394 Output_data_plt_x86_64::add_entry(Symbol* gsym)
 395 {
 396   gold_assert(!gsym->has_plt_offset());
 397
 398   // Note that when setting the PLT offset we skip the initial
 399   // reserved PLT entry.
 400   gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
 401
 402   ++this->count_;
 403
 404   off_t got_offset = this->got_plt_->data_size();
 405
 406   // Every PLT entry needs a GOT entry which points back to the PLT
 407   // entry (this will be changed by the dynamic linker, normally
 408   // lazily when the function is called).
 409   this->got_plt_->set_space_size(got_offset + 8);
 410
 411   // Every PLT entry needs a reloc.
 412   gsym->set_needs_dynsym_entry();
 413   this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_,
 414                          got_offset, 0);
 415
 416   // Note that we don't need to save the symbol.  The contents of the
 417   // PLT are independent of which symbols are used.  The symbols only
 418   // appear in the relocations.
 419 }
 420
 421 // The first entry in the PLT for an executable.
 422
 423 unsigned char Output_data_plt_x86_64::first_plt_entry[plt_entry_size] =
 424 {
 425   // From AMD64 ABI Draft 0.98, page 76
 426   0xff, 0x35,   // pushq contents of memory address
 427   0, 0, 0, 0,   // replaced with address of .got + 4
 428   0xff, 0x25,   // jmp indirect
 429   0, 0, 0, 0,   // replaced with address of .got + 8
 430   0x90, 0x90, 0x90, 0x90   // noop (x4)
 431 };
 432
 433 // Subsequent entries in the PLT for an executable.
 434
 435 unsigned char Output_data_plt_x86_64::plt_entry[plt_entry_size] =
 436 {
 437   // From AMD64 ABI Draft 0.98, page 76
 438   0xff, 0x25,   // jmpq indirect
 439   0, 0, 0, 0,   // replaced with address of symbol in .got
 440   0x68,         // pushq immediate
 441   0, 0, 0, 0,   // replaced with offset into relocation table
 442   0xe9,         // jmpq relative
 443   0, 0, 0, 0    // replaced with offset to start of .plt
 444 };
 445
 446 // Write out the PLT.  This uses the hand-coded instructions above,
 447 // and adjusts them as needed.  This is specified by the AMD64 ABI.
 448
 449 void
 450 Output_data_plt_x86_64::do_write(Output_file* of)
 451 {
 452   const off_t offset = this->offset();
 453   const off_t oview_size = this->data_size();
 454   unsigned char* const oview = of->get_output_view(offset, oview_size);
 455
 456   const off_t got_file_offset = this->got_plt_->offset();
 457   const off_t got_size = this->got_plt_->data_size();
 458   unsigned char* const got_view = of->get_output_view(got_file_offset,
 459                                                       got_size);
 460
 461   unsigned char* pov = oview;
 462
 463   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
 464   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 465
 466   memcpy(pov, first_plt_entry, plt_entry_size);
 467   if (!parameters->output_is_shared())
 468     {
 469       // We do a jmp relative to the PC at the end of this instruction.
 470       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 8
 471                                                   - (plt_address + 6));
 472       elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 16
 473                                         - (plt_address + 12));
 474     }
 475   pov += plt_entry_size;
 476
 477   unsigned char* got_pov = got_view;
 478
 479   memset(got_pov, 0, 24);
 480   got_pov += 24;
 481
 482   unsigned int plt_offset = plt_entry_size;
 483   unsigned int got_offset = 24;
 484   const unsigned int count = this->count_;
 485   for (unsigned int plt_index = 0;
 486        plt_index < count;
 487        ++plt_index,
 488          pov += plt_entry_size,
 489          got_pov += 8,
 490          plt_offset += plt_entry_size,
 491          got_offset += 8)
 492     {
 493       // Set and adjust the PLT entry itself.
 494       memcpy(pov, plt_entry, plt_entry_size);
 495       if (parameters->output_is_shared())
 496         // FIXME(csilvers): what's the right thing to write here?
 497         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
 498       else
 499         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 500                                                     (got_address + got_offset
 501                                                      - (plt_address + plt_offset
 502                                                         + 6)));
 503
 504       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_index);
 505       elfcpp::Swap<32, false>::writeval(pov + 12,
 506                                         - (plt_offset + plt_entry_size));
 507
 508       // Set the entry in the GOT.
 509       elfcpp::Swap<64, false>::writeval(got_pov, plt_address + plt_offset + 6);
 510     }
 511
 512   gold_assert(pov - oview == oview_size);
 513   gold_assert(got_pov - got_view == got_size);
 514
 515   of->write_output_view(offset, oview_size, oview);
 516   of->write_output_view(got_file_offset, got_size, got_view);
 517 }
 518
 519 // Create a PLT entry for a global symbol.
 520
 521 void
 522 Target_x86_64::make_plt_entry(Symbol_table* symtab, Layout* layout,
 523                               Symbol* gsym)
 524 {
 525   if (gsym->has_plt_offset())
 526     return;
 527
 528   if (this->plt_ == NULL)
 529     {
 530       // Create the GOT sections first.
 531       this->got_section(symtab, layout);
 532
 533       this->plt_ = new Output_data_plt_x86_64(layout, this->got_plt_);
 534       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 535                                       (elfcpp::SHF_ALLOC
 536                                        | elfcpp::SHF_EXECINSTR),
 537                                       this->plt_);
 538     }
 539
 540   this->plt_->add_entry(gsym);
 541 }
 542
 543 // Handle a relocation against a non-function symbol defined in a
 544 // dynamic object.  The traditional way to handle this is to generate
 545 // a COPY relocation to copy the variable at runtime from the shared
 546 // object into the executable's data segment.  However, this is
 547 // undesirable in general, as if the size of the object changes in the
 548 // dynamic object, the executable will no longer work correctly.  If
 549 // this relocation is in a writable section, then we can create a
 550 // dynamic reloc and the dynamic linker will resolve it to the correct
 551 // address at runtime.  However, we do not want do that if the
 552 // relocation is in a read-only section, as it would prevent the
 553 // readonly segment from being shared.  And if we have to eventually
 554 // generate a COPY reloc, then any dynamic relocations will be
 555 // useless.  So this means that if this is a writable section, we need
 556 // to save the relocation until we see whether we have to create a
 557 // COPY relocation for this symbol for any other relocation.
 558
 559 void
 560 Target_x86_64::copy_reloc(const General_options* options,
 561                         Symbol_table* symtab,
 562                         Layout* layout,
 563                         Sized_relobj<64, false>* object,
 564                         unsigned int data_shndx, Symbol* gsym,
 565                         const elfcpp::Rela<64, false>& rel)
 566 {
 567   Sized_symbol<64>* ssym;
 568   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(64) (gsym
 569                                                         SELECT_SIZE(64));
 570
 571   if (!Copy_relocs<64, false>::need_copy_reloc(options, object,
 572                                                data_shndx, ssym))
 573     {
 574       // So far we do not need a COPY reloc.  Save this relocation.
 575       // If it turns out that we never need a COPY reloc for this
 576       // symbol, then we will emit the relocation.
 577       if (this->copy_relocs_ == NULL)
 578         this->copy_relocs_ = new Copy_relocs<64, false>();
 579       this->copy_relocs_->save(ssym, object, data_shndx, rel);
 580     }
 581   else
 582     {
 583       // Allocate space for this symbol in the .bss section.
 584
 585       elfcpp::Elf_types<64>::Elf_WXword symsize = ssym->symsize();
 586
 587       // There is no defined way to determine the required alignment
 588       // of the symbol.  We pick the alignment based on the size.  We
 589       // set an arbitrary maximum of 256.
 590       unsigned int align;
 591       for (align = 1; align < 512; align <<= 1)
 592         if ((symsize & align) != 0)
 593           break;
 594
 595       if (this->dynbss_ == NULL)
 596         {
 597           this->dynbss_ = new Output_data_space(align);
 598           layout->add_output_section_data(".bss",
 599                                           elfcpp::SHT_NOBITS,
 600                                           (elfcpp::SHF_ALLOC
 601                                            | elfcpp::SHF_WRITE),
 602                                           this->dynbss_);
 603         }
 604
 605       Output_data_space* dynbss = this->dynbss_;
 606
 607       if (align > dynbss->addralign())
 608         dynbss->set_space_alignment(align);
 609
 610       off_t dynbss_size = dynbss->data_size();
 611       dynbss_size = align_address(dynbss_size, align);
 612       off_t offset = dynbss_size;
 613       dynbss->set_space_size(dynbss_size + symsize);
 614
 615       // Define the symbol in the .dynbss section.
 616       symtab->define_in_output_data(this, ssym->name(), ssym->version(),
 617                                     dynbss, offset, symsize, ssym->type(),
 618                                     ssym->binding(), ssym->visibility(),
 619                                     ssym->nonvis(), false, false);
 620
 621       // Add the COPY reloc.
 622       ssym->set_needs_dynsym_entry();
 623       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
 624       // TODO(csilvers): should last arg here be rel.get_r_addend?
 625       rel_dyn->add_global(ssym, elfcpp::R_X86_64_COPY, dynbss, offset, 0);
 626     }
 627 }
 628
 629
 630 // Optimize the TLS relocation type based on what we know about the
 631 // symbol.  IS_FINAL is true if the final address of this symbol is
 632 // known at link time.
 633
 634 unsigned int
 635 Target_x86_64::optimize_tls_reloc(bool is_final, int r_type)
 636 {
 637   return is_final ? r_type : 0;
 638 #if 0
 639   // If we are generating a shared library, then we can't do anything
 640   // in the linker.
 641   if (parameters->output_is_shared())
 642     return r_type;
 643
 644   switch (r_type)
 645     {
 646     case elfcpp::R_X86_64_TLSGD:
 647       // These are Global-Dynamic which permits fully general TLS
 648       // access.  Since we know that we are generating an executable,
 649       // we can convert this to Initial-Exec.  If we also know that
 650       // this is a local symbol, we can further switch to Local-Exec.
 651       if (is_final)
 652         return elfcpp::R_X86_64_TLS_LE_64;
 653       return elfcpp::R_X86_64_TLS_IE_64;
 654
 655     case elfcpp::R_X86_64_TLS_LDM:
 656       // This is Local-Dynamic, which refers to a local symbol in the
 657       // dynamic TLS block.  Since we know that we generating an
 658       // executable, we can switch to Local-Exec.
 659       return elfcpp::R_X86_64_TLS_LE_64;
 660
 661     case elfcpp::R_X86_64_TLS_LDO_64:
 662       // Another type of Local-Dynamic relocation.
 663       return elfcpp::R_X86_64_TLS_LE;
 664
 665     case elfcpp::R_X86_64_TLS_IE:
 666     case elfcpp::R_X86_64_TLS_GOTIE:
 667     case elfcpp::R_X86_64_TLS_IE_64:
 668       // These are Initial-Exec relocs which get the thread offset
 669       // from the GOT.  If we know that we are linking against the
 670       // local symbol, we can switch to Local-Exec, which links the
 671       // thread offset into the instruction.
 672       if (is_final)
 673         return elfcpp::R_X86_64_TLS_LE_64;
 674       return r_type;
 675
 676     case elfcpp::R_X86_64_TLS_LE:
 677     case elfcpp::R_X86_64_TLS_LE_64:
 678       // When we already have Local-Exec, there is nothing further we
 679       // can do.
 680       return r_type;
 681
 682     default:
 683       gold_unreachable();
 684     }
 685 #endif
 686 }
 687
 688 // Scan a relocation for a local symbol.
 689
 690 inline void
 691 Target_x86_64::Scan::local(const General_options&,
 692                          Symbol_table* symtab,
 693                          Layout* layout,
 694                          Target_x86_64* target,
 695                          Sized_relobj<64, false>* object,
 696                          unsigned int,
 697                          const elfcpp::Rela<64, false>&,
 698                          unsigned int r_type,
 699                          const elfcpp::Sym<64, false>&)
 700 {
 701   switch (r_type)
 702     {
 703     case elfcpp::R_X86_64_NONE:
 704     case elfcpp::R_386_GNU_VTINHERIT:
 705     case elfcpp::R_386_GNU_VTENTRY:
 706       break;
 707
 708     case elfcpp::R_X86_64_64:
 709     case elfcpp::R_X86_64_32:
 710     case elfcpp::R_X86_64_32S:
 711     case elfcpp::R_X86_64_16:
 712     case elfcpp::R_X86_64_8:
 713       // FIXME: If we are generating a shared object we need to copy
 714       // this relocation into the object.
 715       gold_assert(!parameters->output_is_shared());
 716       break;
 717
 718     case elfcpp::R_X86_64_PC64:
 719     case elfcpp::R_X86_64_PC32:
 720     case elfcpp::R_X86_64_PC16:
 721     case elfcpp::R_X86_64_PC8:
 722       break;
 723
 724     case elfcpp::R_X86_64_GOTPC32:  // TODO(csilvers): correct?
 725     case elfcpp::R_X86_64_GOTOFF64:
 726     case elfcpp::R_X86_64_GOTPC64:  // TODO(csilvers): correct?
 727     case elfcpp::R_X86_64_PLTOFF64:  // TODO(csilvers): correct?
 728       // We need a GOT section.
 729       target->got_section(symtab, layout);
 730       break;
 731
 732     case elfcpp::R_X86_64_COPY:
 733     case elfcpp::R_X86_64_GLOB_DAT:
 734     case elfcpp::R_X86_64_JUMP_SLOT:
 735     case elfcpp::R_X86_64_RELATIVE:
 736     case elfcpp::R_X86_64_TPOFF64:
 737     case elfcpp::R_X86_64_TPOFF32:
 738     case elfcpp::R_X86_64_DTPMOD64:
 739     case elfcpp::R_X86_64_DTPOFF64:
 740     case elfcpp::R_X86_64_DTPOFF32:
 741     case elfcpp::R_X86_64_GOTTPOFF:  // TODO(csilvers): correct?
 742     case elfcpp::R_X86_64_TLSDESC:
 743     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // TODO(csilvers): correct?
 744     case elfcpp::R_X86_64_TLSDESC_CALL:  // TODO(csilvers): correct?
 745       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
 746               program_name, object->name().c_str(), r_type);
 747       gold_exit(false);
 748       break;
 749
 750 #if 0
 751     case elfcpp::R_X86_64_TLSGD:  // TODO(csilvers): correct?
 752     case elfcpp::R_X86_64_TLSLD:  // TODO(csilvers): correct?
 753
 754     case elfcpp::R_386_TLS_IE:
 755     case elfcpp::R_386_TLS_GOTIE:
 756     case elfcpp::R_386_TLS_LE:
 757     case elfcpp::R_386_TLS_GD:
 758     case elfcpp::R_386_TLS_LDM:
 759     case elfcpp::R_386_TLS_LDO_64:
 760     case elfcpp::R_386_TLS_IE_64:
 761     case elfcpp::R_386_TLS_LE_64:
 762       {
 763         bool output_is_shared = parameters->output_is_shared();
 764         r_type = Target_x86_64::optimize_tls_reloc(!output_is_shared,
 765                                                  r_type);
 766         switch (r_type)
 767           {
 768           case elfcpp::R_X86_64_TLS_LE:
 769           case elfcpp::R_X86_64_TLS_LE_64:
 770             // FIXME: If generating a shared object, we need to copy
 771             // this relocation into the object.
 772             gold_assert(!output_is_shared);
 773             break;
 774
 775           case elfcpp::R_X86_64_TLS_IE:
 776           case elfcpp::R_X86_64_TLS_GOTIE:
 777           case elfcpp::R_X86_64_TLS_GD:
 778           case elfcpp::R_X86_64_TLS_LDM:
 779           case elfcpp::R_X86_64_TLS_LDO_64:
 780           case elfcpp::R_X86_64_TLS_IE_64:
 781             fprintf(stderr,
 782                     _("%s: %s: unsupported reloc %u against local symbol\n"),
 783                     program_name, object->name().c_str(), r_type);
 784             break;
 785           }
 786       }
 787       break;
 788 #endif
 789
 790     case elfcpp::R_X86_64_GOT64:  // TODO(csilvers): correct?
 791     case elfcpp::R_X86_64_GOT32:
 792     case elfcpp::R_X86_64_GOTPCREL64:  // TODO(csilvers): correct?
 793     case elfcpp::R_X86_64_GOTPCREL:
 794     case elfcpp::R_X86_64_GOTPLT64:  // TODO(csilvers): correct?
 795     case elfcpp::R_X86_64_PLT32:
 796     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
 797     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
 798 #if 0
 799     case elfcpp::R_386_TLS_GD_64:
 800     case elfcpp::R_386_TLS_GD_PUSH:
 801     case elfcpp::R_386_TLS_GD_CALL:
 802     case elfcpp::R_386_TLS_GD_POP:
 803     case elfcpp::R_386_TLS_LDM_64:
 804     case elfcpp::R_386_TLS_LDM_PUSH:
 805     case elfcpp::R_386_TLS_LDM_CALL:
 806     case elfcpp::R_386_TLS_LDM_POP:
 807 #endif
 808     default:
 809       fprintf(stderr, _("%s: %s: unsupported reloc %u against local symbol\n"),
 810               program_name, object->name().c_str(), r_type);
 811       break;
 812     }
 813 }
 814
 815
 816 // Scan a relocation for a global symbol.
 817
 818 inline void
 819 Target_x86_64::Scan::global(const General_options& options,
 820                           Symbol_table* symtab,
 821                           Layout* layout,
 822                           Target_x86_64* target,
 823                           Sized_relobj<64, false>* object,
 824                           unsigned int data_shndx,
 825                           const elfcpp::Rela<64, false>& reloc,
 826                           unsigned int r_type,
 827                           Symbol* gsym)
 828 {
 829   switch (r_type)
 830     {
 831     case elfcpp::R_X86_64_NONE:
 832     case elfcpp::R_386_GNU_VTINHERIT:
 833     case elfcpp::R_386_GNU_VTENTRY:
 834       break;
 835
 836     case elfcpp::R_X86_64_64:
 837     case elfcpp::R_X86_64_PC64:
 838     case elfcpp::R_X86_64_32:
 839     case elfcpp::R_X86_64_32S:
 840     case elfcpp::R_X86_64_PC32:
 841     case elfcpp::R_X86_64_16:
 842     case elfcpp::R_X86_64_PC16:
 843     case elfcpp::R_X86_64_8:
 844     case elfcpp::R_X86_64_PC8:
 845       // FIXME: If we are generating a shared object we may need to
 846       // copy this relocation into the object.  If this symbol is
 847       // defined in a shared object, we may need to copy this
 848       // relocation in order to avoid a COPY relocation.
 849       gold_assert(!parameters->output_is_shared());
 850
 851       if (gsym->is_from_dynobj())
 852         {
 853           // This symbol is defined in a dynamic object.  If it is a
 854           // function, we make a PLT entry.  Otherwise we need to
 855           // either generate a COPY reloc or copy this reloc.
 856           if (gsym->type() == elfcpp::STT_FUNC)
 857             {
 858               target->make_plt_entry(symtab, layout, gsym);
 859
 860               // If this is not a PC relative reference, then we may
 861               // be taking the address of the function.  In that case
 862               // we need to set the entry in the dynamic symbol table
 863               // to the address of the PLT entry.
 864               if (r_type != elfcpp::R_X86_64_PC64
 865                   && r_type != elfcpp::R_X86_64_PC32
 866                   && r_type != elfcpp::R_X86_64_PC16
 867                   && r_type != elfcpp::R_X86_64_PC8)
 868                 gsym->set_needs_dynsym_value();
 869             }
 870           else
 871             target->copy_reloc(&options, symtab, layout, object, data_shndx,
 872                                gsym, reloc);
 873         }
 874
 875       break;
 876
 877     case elfcpp::R_X86_64_GOT64:
 878     case elfcpp::R_X86_64_GOT32:
 879     case elfcpp::R_X86_64_GOTPCREL64:
 880     case elfcpp::R_X86_64_GOTPCREL:
 881     case elfcpp::R_X86_64_GOTPLT64:
 882       {
 883         // The symbol requires a GOT entry.
 884         Output_data_got<64, false>* got = target->got_section(symtab, layout);
 885         if (got->add_global(gsym))
 886           {
 887             // If this symbol is not fully resolved, we need to add a
 888             // dynamic relocation for it.
 889             if (!gsym->final_value_is_known())
 890               {
 891                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 892                 rel_dyn->add_global(gsym, elfcpp::R_X86_64_GLOB_DAT, got,
 893                                     gsym->got_offset(), 0);
 894               }
 895           }
 896       }
 897       break;
 898
 899     case elfcpp::R_X86_64_PLT32:
 900       // If the symbol is fully resolved, this is just a PC32 reloc.
 901       // Otherwise we need a PLT entry.
 902       if (gsym->final_value_is_known())
 903         break;
 904       target->make_plt_entry(symtab, layout, gsym);
 905       break;
 906
 907     case elfcpp::R_X86_64_GOTPC32:  // TODO(csilvers): correct?
 908     case elfcpp::R_X86_64_GOTOFF64:
 909     case elfcpp::R_X86_64_GOTPC64:  // TODO(csilvers): correct?
 910     case elfcpp::R_X86_64_PLTOFF64:  // TODO(csilvers): correct?
 911       // We need a GOT section.
 912       target->got_section(symtab, layout);
 913       break;
 914
 915     case elfcpp::R_X86_64_COPY:
 916     case elfcpp::R_X86_64_GLOB_DAT:
 917     case elfcpp::R_X86_64_JUMP_SLOT:
 918     case elfcpp::R_X86_64_RELATIVE:
 919     case elfcpp::R_X86_64_TPOFF64:
 920     case elfcpp::R_X86_64_TPOFF32:
 921     case elfcpp::R_X86_64_DTPMOD64:
 922     case elfcpp::R_X86_64_DTPOFF64:
 923     case elfcpp::R_X86_64_DTPOFF32:
 924     case elfcpp::R_X86_64_GOTTPOFF:  // TODO(csilvers): correct?
 925     case elfcpp::R_X86_64_TLSDESC:
 926     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // TODO(csilvers): correct?
 927     case elfcpp::R_X86_64_TLSDESC_CALL:  // TODO(csilvers): correct?
 928       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
 929               program_name, object->name().c_str(), r_type);
 930       gold_exit(false);
 931       break;
 932
 933 #if 0
 934     case elfcpp::R_X86_64_TLSGD:  // TODO(csilvers): correct?
 935     case elfcpp::R_X86_64_TLSLD:  // TODO(csilvers): correct?
 936
 937     case elfcpp::R_386_TLS_IE:
 938     case elfcpp::R_386_TLS_GOTIE:
 939     case elfcpp::R_386_TLS_LE:
 940     case elfcpp::R_386_TLS_GD:
 941     case elfcpp::R_386_TLS_LDM:
 942     case elfcpp::R_386_TLS_LDO_64:
 943     case elfcpp::R_386_TLS_IE_64:
 944     case elfcpp::R_386_TLS_LE_64:
 945       {
 946         const bool is_final = gsym->final_value_is_known();
 947         r_type = Target_x86_64::optimize_tls_reloc(is_final, r_type);
 948         switch (r_type)
 949           {
 950           case elfcpp::R_386_TLS_LE:
 951           case elfcpp::R_386_TLS_LE_64:
 952             // FIXME: If generating a shared object, we need to copy
 953             // this relocation into the object.
 954             gold_assert(!parameters->output_is_shared());
 955             break;
 956
 957           case elfcpp::R_386_TLS_IE:
 958           case elfcpp::R_386_TLS_GOTIE:
 959           case elfcpp::R_386_TLS_GD:
 960           case elfcpp::R_386_TLS_LDM:
 961           case elfcpp::R_386_TLS_LDO_64:
 962           case elfcpp::R_386_TLS_IE_64:
 963             fprintf(stderr,
 964                     _("%s: %s: unsupported reloc %u "
 965                       "against global symbol %s\n"),
 966                     program_name, object->name().c_str(), r_type,
 967                     gsym->name());
 968             break;
 969           }
 970       }
 971       break;
 972 #endif
 973
 974     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
 975     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
 976 #if 0
 977     case elfcpp::R_386_TLS_GD_64:
 978     case elfcpp::R_386_TLS_GD_PUSH:
 979     case elfcpp::R_386_TLS_GD_CALL:
 980     case elfcpp::R_386_TLS_GD_POP:
 981     case elfcpp::R_386_TLS_LDM_64:
 982     case elfcpp::R_386_TLS_LDM_PUSH:
 983     case elfcpp::R_386_TLS_LDM_CALL:
 984     case elfcpp::R_386_TLS_LDM_POP:
 985 #endif
 986     default:
 987       fprintf(stderr,
 988               _("%s: %s: unsupported reloc %u against global symbol %s\n"),
 989               program_name, object->name().c_str(), r_type, gsym->name());
 990       break;
 991     }
 992 }
 993
 994 // Scan relocations for a section.
 995
 996 void
 997 Target_x86_64::scan_relocs(const General_options& options,
 998                          Symbol_table* symtab,
 999                          Layout* layout,
1000                          Sized_relobj<64, false>* object,
1001                          unsigned int data_shndx,
1002                          unsigned int sh_type,
1003                          const unsigned char* prelocs,
1004                          size_t reloc_count,
1005                          size_t local_symbol_count,
1006                          const unsigned char* plocal_symbols,
1007                          Symbol** global_symbols)
1008 {
1009   if (sh_type == elfcpp::SHT_REL)
1010     {
1011       fprintf(stderr, _("%s: %s: unsupported REL reloc section\n"),
1012               program_name, object->name().c_str());
1013       gold_exit(false);
1014     }
1015
1016   gold::scan_relocs<64, false, Target_x86_64, elfcpp::SHT_RELA,
1017       Target_x86_64::Scan>(
1018     options,
1019     symtab,
1020     layout,
1021     this,
1022     object,
1023     data_shndx,
1024     prelocs,
1025     reloc_count,
1026     local_symbol_count,
1027     plocal_symbols,
1028     global_symbols);
1029 }
1030
1031 // Finalize the sections.
1032
1033 void
1034 Target_x86_64::do_finalize_sections(Layout* layout)
1035 {
1036   // Fill in some more dynamic tags.
1037   Output_data_dynamic* const odyn = layout->dynamic_data();
1038   if (odyn != NULL)
1039     {
1040       if (this->got_plt_ != NULL)
1041         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1042
1043       if (this->plt_ != NULL)
1044         {
1045           const Output_data* od = this->plt_->rel_plt();
1046           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1047           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1048           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_RELA);
1049         }
1050
1051       if (this->rel_dyn_ != NULL)
1052         {
1053           const Output_data* od = this->rel_dyn_;
1054           odyn->add_section_address(elfcpp::DT_RELA, od);
1055           odyn->add_section_size(elfcpp::DT_RELASZ, od);
1056           odyn->add_constant(elfcpp::DT_RELAENT,
1057                              elfcpp::Elf_sizes<64>::rela_size);
1058         }
1059
1060       if (!parameters->output_is_shared())
1061         {
1062           // The value of the DT_DEBUG tag is filled in by the dynamic
1063           // linker at run time, and used by the debugger.
1064           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1065         }
1066     }
1067
1068   // Emit any relocs we saved in an attempt to avoid generating COPY
1069   // relocs.
1070   if (this->copy_relocs_ == NULL)
1071     return;
1072   if (this->copy_relocs_->any_to_emit())
1073     {
1074       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1075       this->copy_relocs_->emit(rel_dyn);
1076     }
1077   delete this->copy_relocs_;
1078   this->copy_relocs_ = NULL;
1079 }
1080
1081 // Perform a relocation.
1082
1083 inline bool
1084 Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo,
1085                                   Target_x86_64* target,
1086                                   size_t relnum,
1087                                   const elfcpp::Rela<64, false>& rel,
1088                                   unsigned int r_type,
1089                                   const Sized_symbol<64>* gsym,
1090                                   const Symbol_value<64>* psymval,
1091                                   unsigned char* view,
1092                                   elfcpp::Elf_types<64>::Elf_Addr address,
1093                                   off_t view_size)
1094 {
1095   if (this->skip_call_tls_get_addr_)
1096     {
1097       if (r_type != elfcpp::R_X86_64_PLT32
1098           || gsym == NULL
1099           || strcmp(gsym->name(), "___tls_get_addr") != 0)
1100         {
1101           fprintf(stderr, _("%s: %s: missing expected TLS relocation\n"),
1102                   program_name,
1103                   relinfo->location(relnum, rel.get_r_offset()).c_str());
1104           gold_exit(false);
1105         }
1106
1107       this->skip_call_tls_get_addr_ = false;
1108
1109       return false;
1110     }
1111
1112   // Pick the value to use for symbols defined in shared objects.
1113   Symbol_value<64> symval;
1114   if (gsym != NULL && gsym->is_from_dynobj() && gsym->has_plt_offset())
1115     {
1116       symval.set_output_value(target->plt_section()->address()
1117                               + gsym->plt_offset());
1118       psymval = &symval;
1119     }
1120
1121   const Sized_relobj<64, false>* object = relinfo->object;
1122   const elfcpp::Elf_Xword addend = rel.get_r_addend();
1123
1124   switch (r_type)
1125     {
1126     case elfcpp::R_X86_64_NONE:
1127     case elfcpp::R_386_GNU_VTINHERIT:
1128     case elfcpp::R_386_GNU_VTENTRY:
1129       break;
1130
1131     case elfcpp::R_X86_64_64:
1132       Relocate_functions<64, false>::rela64(view, object, psymval, addend);
1133       break;
1134
1135     case elfcpp::R_X86_64_PC64:
1136       Relocate_functions<64, false>::pcrela64(view, object, psymval, addend,
1137                                               address);
1138       break;
1139
1140     case elfcpp::R_X86_64_32:
1141       // FIXME: we need to verify that value + addend fits into 32 bits:
1142       //    uint64_t x = value + addend;
1143       //    x == static_cast<uint64_t>(static_cast<uint32_t>(x))
1144       // Likewise for other <=32-bit relocations (but see R_X86_64_32S).
1145       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1146       break;
1147
1148     case elfcpp::R_X86_64_32S:
1149       // FIXME: we need to verify that value + addend fits into 32 bits:
1150       //    int64_t x = value + addend;   // note this quantity is signed!
1151       //    x == static_cast<int64_t>(static_cast<int32_t>(x))
1152       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1153       break;
1154
1155     case elfcpp::R_X86_64_PC32:
1156       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1157                                               address);
1158       break;
1159
1160     case elfcpp::R_X86_64_16:
1161       Relocate_functions<64, false>::rela16(view, object, psymval, addend);
1162       break;
1163
1164     case elfcpp::R_X86_64_PC16:
1165       Relocate_functions<64, false>::pcrela16(view, object, psymval, addend,
1166                                               address);
1167       break;
1168
1169     case elfcpp::R_X86_64_8:
1170       Relocate_functions<64, false>::rela8(view, object, psymval, addend);
1171       break;
1172
1173     case elfcpp::R_X86_64_PC8:
1174       Relocate_functions<64, false>::pcrela8(view, object, psymval, addend,
1175                                              address);
1176       break;
1177
1178     case elfcpp::R_X86_64_PLT32:
1179       gold_assert(gsym->has_plt_offset()
1180                   || gsym->final_value_is_known());
1181       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1182                                               address);
1183       break;
1184
1185     case elfcpp::R_X86_64_GOT32:
1186       // Local GOT offsets not yet supported.
1187       gold_assert(gsym);
1188       gold_assert(gsym->has_got_offset());
1189       Relocate_functions<64, false>::rela32(view, gsym->got_offset(), addend);
1190       break;
1191
1192     case elfcpp::R_X86_64_GOTPC32:
1193       {
1194         gold_assert(gsym);
1195         elfcpp::Elf_types<64>::Elf_Addr value;
1196         value = target->got_section(NULL, NULL)->address();
1197         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1198       }
1199       break;
1200
1201     case elfcpp::R_X86_64_GOT64:
1202       // The ABI doc says "Like GOT64, but indicates a PLT entry is needed."
1203       // Since we always add a PLT entry, this is equivalent.
1204     case elfcpp::R_X86_64_GOTPLT64:  // TODO(csilvers): correct?
1205       // Local GOT offsets not yet supported.
1206       gold_assert(gsym);
1207       gold_assert(gsym->has_got_offset());
1208       Relocate_functions<64, false>::rela64(view, gsym->got_offset(), addend);
1209       break;
1210
1211     case elfcpp::R_X86_64_GOTPC64:
1212       {
1213         gold_assert(gsym);
1214         elfcpp::Elf_types<64>::Elf_Addr value;
1215         value = target->got_section(NULL, NULL)->address();
1216         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1217       }
1218       break;
1219
1220     case elfcpp::R_X86_64_GOTOFF64:
1221       {
1222         elfcpp::Elf_types<64>::Elf_Addr value;
1223         value = (psymval->value(object, 0)
1224                  - target->got_section(NULL, NULL)->address());
1225         Relocate_functions<64, false>::rela64(view, value, addend);
1226       }
1227       break;
1228
1229     case elfcpp::R_X86_64_GOTPCREL:
1230       {
1231         // Local GOT offsets not yet supported.
1232         gold_assert(gsym);
1233         gold_assert(gsym->has_got_offset());
1234         elfcpp::Elf_types<64>::Elf_Addr value;
1235         value = (target->got_section(NULL, NULL)->address()
1236                  + gsym->got_offset());
1237         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1238       }
1239       break;
1240
1241     case elfcpp::R_X86_64_GOTPCREL64:
1242       {
1243         // Local GOT offsets not yet supported.
1244         gold_assert(gsym);
1245         gold_assert(gsym->has_got_offset());
1246         elfcpp::Elf_types<64>::Elf_Addr value;
1247         value = (target->got_section(NULL, NULL)->address()
1248                  + gsym->got_offset());
1249         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1250       }
1251       break;
1252
1253     case elfcpp::R_X86_64_COPY:
1254     case elfcpp::R_X86_64_GLOB_DAT:
1255     case elfcpp::R_X86_64_JUMP_SLOT:
1256     case elfcpp::R_X86_64_RELATIVE:
1257     case elfcpp::R_X86_64_TPOFF64:
1258     case elfcpp::R_X86_64_TPOFF32:
1259     case elfcpp::R_X86_64_DTPMOD64:
1260     case elfcpp::R_X86_64_DTPOFF64:
1261     case elfcpp::R_X86_64_DTPOFF32:
1262     case elfcpp::R_X86_64_GOTTPOFF:  // TODO(csilvers): correct?
1263     case elfcpp::R_X86_64_TLSDESC:
1264     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // TODO(csilvers): correct?
1265     case elfcpp::R_X86_64_TLSDESC_CALL:  // TODO(csilvers): correct?
1266       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
1267               program_name,
1268               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1269               r_type);
1270       gold_exit(false);
1271       break;
1272
1273 #if 0
1274     case elfcpp::R_X86_64_TLSGD:  // TODO(csilvers): correct?
1275     case elfcpp::R_X86_64_TLSLD:  // TODO(csilvers): correct?
1276
1277     case elfcpp::R_386_TLS_IE:
1278     case elfcpp::R_386_TLS_GOTIE:
1279     case elfcpp::R_386_TLS_LE:
1280     case elfcpp::R_386_TLS_GD:
1281     case elfcpp::R_386_TLS_LDM:
1282     case elfcpp::R_386_TLS_LDO_64:
1283     case elfcpp::R_386_TLS_IE_64:
1284     case elfcpp::R_386_TLS_LE_64:
1285       this->relocate_tls(relinfo, relnum, rel, r_type, gsym, psymval, view,
1286                          address, view_size);
1287       break;
1288 #else
1289       view_size++;      // this is to make view_size used
1290 #endif
1291
1292     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
1293     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
1294     case elfcpp::R_X86_64_PLTOFF64:  // TODO(csilvers): implement me!
1295 #if 0
1296     case elfcpp::R_386_TLS_GD_64:
1297     case elfcpp::R_386_TLS_GD_PUSH:
1298     case elfcpp::R_386_TLS_GD_CALL:
1299     case elfcpp::R_386_TLS_GD_POP:
1300     case elfcpp::R_386_TLS_LDM_64:
1301     case elfcpp::R_386_TLS_LDM_PUSH:
1302     case elfcpp::R_386_TLS_LDM_CALL:
1303     case elfcpp::R_386_TLS_LDM_POP:
1304 #endif
1305     default:
1306       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1307               program_name,
1308               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1309               r_type);
1310       // gold_exit(false);
1311       break;
1312     }
1313
1314   return true;
1315 }
1316
1317 // Perform a TLS relocation.
1318
1319 inline void
1320 Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>*, // relinfo,
1321                                       size_t , // relnum,
1322                                       const elfcpp::Rela<64, false>& , // rel,
1323                                       unsigned int , // r_type,
1324                                       const Sized_symbol<64>* , // gsym,
1325                                       const Symbol_value<64>* , // psymval,
1326                                       unsigned char* , // view,
1327                                       elfcpp::Elf_types<64>::Elf_Addr,
1328                                       off_t)// view_size)
1329 {
1330 #if 0
1331   Output_segment* tls_segment = relinfo->layout->tls_segment();
1332   if (tls_segment == NULL)
1333     {
1334       fprintf(stderr, _("%s: %s: TLS reloc but no TLS segment\n"),
1335               program_name,
1336               relinfo->location(relnum, rel.get_r_offset()).c_str());
1337       gold_exit(false);
1338     }
1339
1340   elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0);
1341
1342   const bool is_final = (gsym == NULL
1343                          ? !parameters->output_is_shared()
1344                          : gsym->final_value_is_known());
1345   const unsigned int opt_r_type =
1346     Target_x86_64::optimize_tls_reloc(is_final, r_type);
1347   switch (r_type)
1348     {
1349     case elfcpp::R_X86_64_TLS_LE_64:
1350       value = tls_segment->vaddr() + tls_segment->memsz() - value;
1351       Relocate_functions<64, false>::rel64(view, value);
1352       break;
1353
1354     case elfcpp::R_X86_64_TLS_LE:
1355       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1356       Relocate_functions<64, false>::rel64(view, value);
1357       break;
1358
1359     case elfcpp::R_X86_64_TLS_IE:
1360     case elfcpp::R_X86_64_TLS_GOTIE:
1361     case elfcpp::R_X86_64_TLS_IE_64:
1362       if (opt_r_type == elfcpp::R_X86_64_TLS_LE_64)
1363         {
1364           Target_x86_64::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1365                                               rel, r_type, value, view,
1366                                               view_size);
1367           break;
1368         }
1369       fprintf(stderr, _("%s: %s: unsupported reloc type %u\n"),
1370               program_name,
1371               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1372               r_type);
1373       // gold_exit(false);
1374       break;
1375
1376     case elfcpp::R_X86_64_TLS_GD:
1377       if (opt_r_type == elfcpp::R_X86_64_TLS_LE_64)
1378         {
1379           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1380                              rel, r_type, value, view,
1381                              view_size);
1382           break;
1383         }
1384       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1385               program_name,
1386               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1387               r_type);
1388       // gold_exit(false);
1389       break;
1390
1391     case elfcpp::R_X86_64_TLS_LDM:
1392     case elfcpp::R_X86_64_TLS_LDO_64:
1393       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1394               program_name,
1395               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1396               r_type);
1397       // gold_exit(false);
1398       break;
1399     }
1400 #endif
1401 }
1402
1403 // Do a relocation in which we convert a TLS Initial-Exec to a
1404 // Local-Exec.
1405
1406 inline void
1407 Target_x86_64::Relocate::tls_ie_to_le(const Relocate_info<64, false>* , // relinfo,
1408                                     size_t , // relnum,
1409                                     Output_segment* , // tls_segment,
1410                                     const elfcpp::Rela<64, false>& , // rel,
1411                                     unsigned int , // r_type,
1412                                     elfcpp::Elf_types<64>::Elf_Addr , // value,
1413                                     unsigned char* , // view,
1414                                       off_t) // view_size)
1415 {
1416 #if 0
1417   // We have to actually change the instructions, which means that we
1418   // need to examine the opcodes to figure out which instruction we
1419   // are looking at.
1420   if (r_type == elfcpp::R_X86_64_TLS_IE)
1421     {
1422       // movl %gs:XX,%eax  ==>  movl $YY,%eax
1423       // movl %gs:XX,%reg  ==>  movl $YY,%reg
1424       // addl %gs:XX,%reg  ==>  addl $YY,%reg
1425       Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, -1);
1426       Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, 4);
1427
1428       unsigned char op1 = view[-1];
1429       if (op1 == 0xa1)
1430         {
1431           // movl XX,%eax  ==>  movl $YY,%eax
1432           view[-1] = 0xb8;
1433         }
1434       else
1435         {
1436           Target_x86_64::Relocate::check_range(relinfo, relnum, rel,
1437                                              view_size, -2);
1438
1439           unsigned char op2 = view[-2];
1440           if (op2 == 0x8b)
1441             {
1442               // movl XX,%reg  ==>  movl $YY,%reg
1443               Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1444                                                (op1 & 0xc7) == 0x05);
1445               view[-2] = 0xc7;
1446               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1447             }
1448           else if (op2 == 0x03)
1449             {
1450               // addl XX,%reg  ==>  addl $YY,%reg
1451               Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1452                                                (op1 & 0xc7) == 0x05);
1453               view[-2] = 0x81;
1454               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1455             }
1456           else
1457             Target_x86_64::Relocate::check_tls(relinfo, relnum, rel, 0);
1458         }
1459     }
1460   else
1461     {
1462       // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1463       // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1464       // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1465       Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, -2);
1466       Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, 4);
1467
1468       unsigned char op1 = view[-1];
1469       unsigned char op2 = view[-2];
1470       Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1471                                        (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
1472       if (op2 == 0x8b)
1473         {
1474           // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1475           view[-2] = 0xc7;
1476           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1477         }
1478       else if (op2 == 0x2b)
1479         {
1480           // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1481           view[-2] = 0x81;
1482           view[-1] = 0xe8 | ((op1 >> 3) & 7);
1483         }
1484       else if (op2 == 0x03)
1485         {
1486           // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1487           view[-2] = 0x81;
1488           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1489         }
1490       else
1491         Target_x86_64::Relocate::check_tls(relinfo, relnum, rel, 0);
1492     }
1493
1494   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1495   if (r_type == elfcpp::R_X86_64_TLS_IE || r_type == elfcpp::R_X86_64_TLS_GOTIE)
1496     value = - value;
1497
1498   Relocate_functions<64, false>::rel64(view, value);
1499 #endif
1500 }
1501
1502 // Do a relocation in which we convert a TLS Global-Dynamic to a
1503 // Local-Exec.
1504
1505 inline void
1506 Target_x86_64::Relocate::tls_gd_to_le(const Relocate_info<64, false>* , // relinfo,
1507                                     size_t , // relnum,
1508                                     Output_segment* , // tls_segment,
1509                                     const elfcpp::Rela<64, false>& , // rel,
1510                                     unsigned int,
1511                                     elfcpp::Elf_types<64>::Elf_Addr , // value,
1512                                     unsigned char* , // view,
1513                                       off_t)// view_size)
1514 {
1515 #if 0
1516   // leal foo(,%reg,1),%eax; call ___tls_get_addr
1517   //  ==> movl %gs,0,%eax; subl $foo@tpoff,%eax
1518   // leal foo(%reg),%eax; call ___tls_get_addr
1519   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1520
1521   Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, -2);
1522   Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, 9);
1523
1524   unsigned char op1 = view[-1];
1525   unsigned char op2 = view[-2];
1526
1527   Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1528                                    op2 == 0x8d || op2 == 0x04);
1529   Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1530                                    view[4] == 0xe8);
1531
1532   int roff = 5;
1533
1534   if (op2 == 0x04)
1535     {
1536       Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, -3);
1537       Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1538                                        view[-3] == 0x8d);
1539       Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1540                                        ((op1 & 0xc7) == 0x05
1541                                         && op1 != (4 << 3)));
1542       memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1543     }
1544   else
1545     {
1546       Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1547                                        (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1548       if (rel.get_r_offset() + 9 < view_size && view[9] == 0x90)
1549         {
1550           // There is a trailing nop.  Use the size byte subl.
1551           memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1552           roff = 6;
1553         }
1554       else
1555         {
1556           // Use the five byte subl.
1557           memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1558         }
1559     }
1560
1561   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1562   Relocate_functions<64, false>::rel64(view + roff, value);
1563
1564   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1565   // We can skip it.
1566   this->skip_call_tls_get_addr_ = true;
1567 #endif
1568 }
1569
1570 // Check the range for a TLS relocation.
1571
1572 inline void
1573 Target_x86_64::Relocate::check_range(const Relocate_info<64, false>* relinfo,
1574                                    size_t relnum,
1575                                    const elfcpp::Rela<64, false>& rel,
1576                                    off_t view_size, off_t off)
1577 {
1578   off_t offset = rel.get_r_offset() + off;
1579   if (offset < 0 || offset > view_size)
1580     {
1581       fprintf(stderr, _("%s: %s: TLS relocation out of range\n"),
1582               program_name,
1583               relinfo->location(relnum, rel.get_r_offset()).c_str());
1584       gold_exit(false);
1585     }
1586 }
1587
1588 // Check the validity of a TLS relocation.  This is like assert.
1589
1590 inline void
1591 Target_x86_64::Relocate::check_tls(const Relocate_info<64, false>* relinfo,
1592                                  size_t relnum,
1593                                  const elfcpp::Rela<64, false>& rel,
1594                                  bool valid)
1595 {
1596   if (!valid)
1597     {
1598       fprintf(stderr,
1599               _("%s: %s: TLS relocation against invalid instruction\n"),
1600               program_name,
1601               relinfo->location(relnum, rel.get_r_offset()).c_str());
1602       gold_exit(false);
1603     }
1604 }
1605
1606 // Relocate section data.
1607
1608 void
1609 Target_x86_64::relocate_section(const Relocate_info<64, false>* relinfo,
1610                               unsigned int sh_type,
1611                               const unsigned char* prelocs,
1612                               size_t reloc_count,
1613                               unsigned char* view,
1614                               elfcpp::Elf_types<64>::Elf_Addr address,
1615                               off_t view_size)
1616 {
1617   gold_assert(sh_type == elfcpp::SHT_RELA);
1618
1619   gold::relocate_section<64, false, Target_x86_64, elfcpp::SHT_RELA,
1620                          Target_x86_64::Relocate>(
1621     relinfo,
1622     this,
1623     prelocs,
1624     reloc_count,
1625     view,
1626     address,
1627     view_size);
1628 }
1629
1630 // Return the value to use for a dynamic which requires special
1631 // treatment.  This is how we support equality comparisons of function
1632 // pointers across shared library boundaries, as described in the
1633 // processor specific ABI supplement.
1634
1635 uint64_t
1636 Target_x86_64::do_dynsym_value(const Symbol* gsym) const
1637 {
1638   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1639   return this->plt_section()->address() + gsym->plt_offset();
1640 }
1641
1642 // Return a string used to fill a code section with nops to take up
1643 // the specified length.
1644
1645 std::string
1646 Target_x86_64::do_code_fill(off_t length)
1647 {
1648   if (length >= 16)
1649     {
1650       // Build a jmpq instruction to skip over the bytes.
1651       unsigned char jmp[5];
1652       jmp[0] = 0xe9;
1653       elfcpp::Swap_unaligned<64, false>::writeval(jmp + 1, length - 5);
1654       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1655               + std::string(length - 5, '\0'));
1656     }
1657
1658   // Nop sequences of various lengths.
1659   const char nop1[1] = { 0x90 };                   // nop
1660   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1661   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1662   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1663   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1664                          0x00 };                   // leal 0(%esi,1),%esi
1665   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1666                          0x00, 0x00 };
1667   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1668                          0x00, 0x00, 0x00 };
1669   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1670                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1671   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1672                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1673                          0x00 };
1674   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1675                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1676                            0x00, 0x00 };
1677   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1678                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1679                            0x00, 0x00, 0x00 };
1680   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1681                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1682                            0x00, 0x00, 0x00, 0x00 };
1683   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1684                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1685                            0x27, 0x00, 0x00, 0x00,
1686                            0x00 };
1687   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1688                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1689                            0xbc, 0x27, 0x00, 0x00,
1690                            0x00, 0x00 };
1691   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1692                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1693                            0x90, 0x90, 0x90, 0x90,
1694                            0x90, 0x90, 0x90 };
1695
1696   const char* nops[16] = {
1697     NULL,
1698     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1699     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1700   };
1701
1702   return std::string(nops[length], length);
1703 }
1704
1705 // The selector for x86_64 object files.
1706
1707 class Target_selector_x86_64 : public Target_selector
1708 {
1709 public:
1710   Target_selector_x86_64()
1711     : Target_selector(elfcpp::EM_X86_64, 64, false)
1712   { }
1713
1714   Target*
1715   recognize(int machine, int osabi, int abiversion);
1716
1717  private:
1718   Target_x86_64* target_;
1719 };
1720
1721 // Recognize an x86_64 object file when we already know that the machine
1722 // number is EM_X86_64.
1723
1724 Target*
1725 Target_selector_x86_64::recognize(int, int, int)
1726 {
1727   if (this->target_ == NULL)
1728     this->target_ = new Target_x86_64();
1729   return this->target_;
1730 }
1731
1732 Target_selector_x86_64 target_selector_x86_64;
1733
1734 } // End anonymous namespace.