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
  57 //   http://www.x86-64.org/documentation/abi.pdf
  58 // TLS info comes from
  59 //   http://people.redhat.com/drepper/tls.pdf
  60 //   http://ia32-abi.googlegroups.com/web/RFC-TLSDESC-x86.txt?gda=kWQJPEQAAACEfYQFX0dubPQ2NuO4whhjkR4HAp8tBMb_I0iuUeQslmG1qiJ7UbTIup-M2XPURDRiZJyPR4BqKR2agJ-5jfT5Ley2_-oiOJ4zLNAGCw24Bg
  61
  62 class Target_x86_64 : public Sized_target<64, false>
  63 {
  64  public:
  65   // In the x86_64 ABI (p 68), it says "The AMD64 ABI architectures
  66   // uses only Elf64_Rela relocation entries with explicit addends."
  67   typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
  68
  69   Target_x86_64()
  70     : Sized_target<64, false>(&x86_64_info),
  71       got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
  72       copy_relocs_(NULL), dynbss_(NULL)
  73   { }
  74
  75   // Scan the relocations to look for symbol adjustments.
  76   void
  77   scan_relocs(const General_options& options,
  78               Symbol_table* symtab,
  79               Layout* layout,
  80               Sized_relobj<64, false>* object,
  81               unsigned int data_shndx,
  82               unsigned int sh_type,
  83               const unsigned char* prelocs,
  84               size_t reloc_count,
  85               size_t local_symbol_count,
  86               const unsigned char* plocal_symbols,
  87               Symbol** global_symbols);
  88
  89   // Finalize the sections.
  90   void
  91   do_finalize_sections(Layout*);
  92
  93   // Return the value to use for a dynamic which requires special
  94   // treatment.
  95   uint64_t
  96   do_dynsym_value(const Symbol*) const;
  97
  98   // Relocate a section.
  99   void
 100   relocate_section(const Relocate_info<64, false>*,
 101                    unsigned int sh_type,
 102                    const unsigned char* prelocs,
 103                    size_t reloc_count,
 104                    unsigned char* view,
 105                    elfcpp::Elf_types<64>::Elf_Addr view_address,
 106                    off_t view_size);
 107
 108   // Return a string used to fill a code section with nops.
 109   std::string
 110   do_code_fill(off_t length);
 111
 112  private:
 113   // The class which scans relocations.
 114   struct Scan
 115   {
 116     inline void
 117     local(const General_options& options, Symbol_table* symtab,
 118           Layout* layout, Target_x86_64* target,
 119           Sized_relobj<64, false>* object,
 120           unsigned int data_shndx,
 121           const elfcpp::Rela<64, false>& reloc, unsigned int r_type,
 122           const elfcpp::Sym<64, false>& lsym);
 123
 124     inline void
 125     global(const General_options& options, Symbol_table* symtab,
 126            Layout* layout, Target_x86_64* target,
 127            Sized_relobj<64, false>* object,
 128            unsigned int data_shndx,
 129            const elfcpp::Rela<64, false>& reloc, unsigned int r_type,
 130            Symbol* gsym);
 131   };
 132
 133   // The class which implements relocation.
 134   class Relocate
 135   {
 136    public:
 137     Relocate()
 138       : skip_call_tls_get_addr_(false)
 139     { }
 140
 141     ~Relocate()
 142     {
 143       if (this->skip_call_tls_get_addr_)
 144         {
 145           // FIXME: This needs to specify the location somehow.
 146           fprintf(stderr, _("%s: missing expected TLS relocation\n"),
 147                   program_name);
 148           gold_exit(false);
 149         }
 150     }
 151
 152     // Do a relocation.  Return false if the caller should not issue
 153     // any warnings about this relocation.
 154     inline bool
 155     relocate(const Relocate_info<64, false>*, Target_x86_64*, size_t relnum,
 156              const elfcpp::Rela<64, false>&,
 157              unsigned int r_type, const Sized_symbol<64>*,
 158              const Symbol_value<64>*,
 159              unsigned char*, elfcpp::Elf_types<64>::Elf_Addr,
 160              off_t);
 161
 162    private:
 163     // Do a TLS relocation.
 164     inline void
 165     relocate_tls(const Relocate_info<64, false>*, size_t relnum,
 166                  const elfcpp::Rela<64, false>&,
 167                  unsigned int r_type, const Sized_symbol<64>*,
 168                  const Symbol_value<64>*,
 169                  unsigned char*, elfcpp::Elf_types<64>::Elf_Addr, off_t);
 170
 171     // Do a TLS Initial-Exec to Local-Exec transition.
 172     static inline void
 173     tls_ie_to_le(const Relocate_info<64, false>*, size_t relnum,
 174                  Output_segment* tls_segment,
 175                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 176                  elfcpp::Elf_types<64>::Elf_Addr value,
 177                  unsigned char* view,
 178                  off_t view_size);
 179
 180     // Do a TLS Global-Dynamic to Local-Exec transition.
 181     inline void
 182     tls_gd_to_le(const Relocate_info<64, false>*, size_t relnum,
 183                  Output_segment* tls_segment,
 184                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 185                  elfcpp::Elf_types<64>::Elf_Addr value,
 186                  unsigned char* view,
 187                  off_t view_size);
 188
 189     // Check the range for a TLS relocation.
 190     static inline void
 191     check_range(const Relocate_info<64, false>*, size_t relnum,
 192                 const elfcpp::Rela<64, false>&, off_t, off_t);
 193
 194     // Check the validity of a TLS relocation.  This is like assert.
 195     static inline void
 196     check_tls(const Relocate_info<64, false>*, size_t relnum,
 197               const elfcpp::Rela<64, false>&, bool);
 198
 199     // This is set if we should skip the next reloc, which should be a
 200     // PLT32 reloc against ___tls_get_addr.
 201     bool skip_call_tls_get_addr_;
 202   };
 203
 204   // Adjust TLS relocation type based on the options and whether this
 205   // is a local symbol.
 206   static unsigned int
 207   optimize_tls_reloc(bool is_final, int r_type);
 208
 209   // Get the GOT section, creating it if necessary.
 210   Output_data_got<64, false>*
 211   got_section(Symbol_table*, Layout*);
 212
 213   // Create a PLT entry for a global symbol.
 214   void
 215   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 216
 217   // Get the PLT section.
 218   Output_data_plt_x86_64*
 219   plt_section() const
 220   {
 221     gold_assert(this->plt_ != NULL);
 222     return this->plt_;
 223   }
 224
 225   // Get the dynamic reloc section, creating it if necessary.
 226   Reloc_section*
 227   rel_dyn_section(Layout*);
 228
 229   // Copy a relocation against a global symbol.
 230   void
 231   copy_reloc(const General_options*, Symbol_table*, Layout*,
 232              Sized_relobj<64, false>*, unsigned int,
 233              Symbol*, const elfcpp::Rela<64, false>&);
 234
 235   // Information about this specific target which we pass to the
 236   // general Target structure.
 237   static const Target::Target_info x86_64_info;
 238
 239   // The GOT section.
 240   Output_data_got<64, false>* got_;
 241   // The PLT section.
 242   Output_data_plt_x86_64* plt_;
 243   // The GOT PLT section.
 244   Output_data_space* got_plt_;
 245   // The dynamic reloc section.
 246   Reloc_section* rel_dyn_;
 247   // Relocs saved to avoid a COPY reloc.
 248   Copy_relocs<64, false>* copy_relocs_;
 249   // Space for variables copied with a COPY reloc.
 250   Output_data_space* dynbss_;
 251 };
 252
 253 const Target::Target_info Target_x86_64::x86_64_info =
 254 {
 255   64,                   // size
 256   false,                // is_big_endian
 257   elfcpp::EM_X86_64,    // machine_code
 258   false,                // has_make_symbol
 259   false,                // has_resolve
 260   true,                 // has_code_fill
 261   "/lib/ld64.so.1",     // program interpreter
 262   0x400000,             // text_segment_address
 263   0x1000,               // abi_pagesize
 264   0x1000                // common_pagesize
 265 };
 266
 267 // Get the GOT section, creating it if necessary.
 268
 269 Output_data_got<64, false>*
 270 Target_x86_64::got_section(Symbol_table* symtab, Layout* layout)
 271 {
 272   if (this->got_ == NULL)
 273     {
 274       gold_assert(symtab != NULL && layout != NULL);
 275
 276       this->got_ = new Output_data_got<64, false>();
 277
 278       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 279                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 280                                       this->got_);
 281
 282       // The old GNU linker creates a .got.plt section.  We just
 283       // create another set of data in the .got section.  Note that we
 284       // always create a PLT if we create a GOT, although the PLT
 285       // might be empty.
 286       // TODO(csilvers): do we really need an alignment of 8?
 287       this->got_plt_ = new Output_data_space(8);
 288       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 289                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 290                                       this->got_plt_);
 291
 292       // The first three entries are reserved.
 293       this->got_plt_->set_space_size(3 * 8);
 294
 295       // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
 296       symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
 297                                     this->got_plt_,
 298                                     0, 0, elfcpp::STT_OBJECT,
 299                                     elfcpp::STB_LOCAL,
 300                                     elfcpp::STV_HIDDEN, 0,
 301                                     false, false);
 302     }
 303
 304   return this->got_;
 305 }
 306
 307 // Get the dynamic reloc section, creating it if necessary.
 308
 309 Target_x86_64::Reloc_section*
 310 Target_x86_64::rel_dyn_section(Layout* layout)
 311 {
 312   if (this->rel_dyn_ == NULL)
 313     {
 314       gold_assert(layout != NULL);
 315       this->rel_dyn_ = new Reloc_section();
 316       layout->add_output_section_data(".rela.dyn", elfcpp::SHT_RELA,
 317                                       elfcpp::SHF_ALLOC, this->rel_dyn_);
 318     }
 319   return this->rel_dyn_;
 320 }
 321
 322 // A class to handle the PLT data.
 323
 324 class Output_data_plt_x86_64 : public Output_section_data
 325 {
 326  public:
 327   typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
 328
 329   Output_data_plt_x86_64(Layout*, Output_data_space*);
 330
 331   // Add an entry to the PLT.
 332   void
 333   add_entry(Symbol* gsym);
 334
 335   // Return the .rel.plt section data.
 336   const Reloc_section*
 337   rel_plt() const
 338   { return this->rel_; }
 339
 340  protected:
 341   void
 342   do_adjust_output_section(Output_section* os);
 343
 344  private:
 345   // The size of an entry in the PLT.
 346   static const int plt_entry_size = 16;
 347
 348   // The first entry in the PLT.
 349   // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same
 350   // procedure linkage table for both programs and shared objects."
 351   static unsigned char first_plt_entry[plt_entry_size];
 352
 353   // Other entries in the PLT for an executable.
 354   static unsigned char plt_entry[plt_entry_size];
 355
 356   // Set the final size.
 357   void
 358   do_set_address(uint64_t, off_t)
 359   { this->set_data_size((this->count_ + 1) * plt_entry_size); }
 360
 361   // Write out the PLT data.
 362   void
 363   do_write(Output_file*);
 364
 365   // The reloc section.
 366   Reloc_section* rel_;
 367   // The .got.plt section.
 368   Output_data_space* got_plt_;
 369   // The number of PLT entries.
 370   unsigned int count_;
 371 };
 372
 373 // Create the PLT section.  The ordinary .got section is an argument,
 374 // since we need to refer to the start.  We also create our own .got
 375 // section just for PLT entries.
 376
 377 Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout,
 378                                                Output_data_space* got_plt)
 379     // TODO(csilvers): do we really need an alignment of 8?
 380   : Output_section_data(8), got_plt_(got_plt), count_(0)
 381 {
 382   this->rel_ = new Reloc_section();
 383   layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
 384                                   elfcpp::SHF_ALLOC, this->rel_);
 385 }
 386
 387 void
 388 Output_data_plt_x86_64::do_adjust_output_section(Output_section* os)
 389 {
 390   // UnixWare sets the entsize of .plt to 4, and so does the old GNU
 391   // linker, and so do we.
 392   os->set_entsize(4);
 393 }
 394
 395 // Add an entry to the PLT.
 396
 397 void
 398 Output_data_plt_x86_64::add_entry(Symbol* gsym)
 399 {
 400   gold_assert(!gsym->has_plt_offset());
 401
 402   // Note that when setting the PLT offset we skip the initial
 403   // reserved PLT entry.
 404   gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
 405
 406   ++this->count_;
 407
 408   off_t got_offset = this->got_plt_->data_size();
 409
 410   // Every PLT entry needs a GOT entry which points back to the PLT
 411   // entry (this will be changed by the dynamic linker, normally
 412   // lazily when the function is called).
 413   this->got_plt_->set_space_size(got_offset + 8);
 414
 415   // Every PLT entry needs a reloc.
 416   gsym->set_needs_dynsym_entry();
 417   this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_,
 418                          got_offset, 0);
 419
 420   // Note that we don't need to save the symbol.  The contents of the
 421   // PLT are independent of which symbols are used.  The symbols only
 422   // appear in the relocations.
 423 }
 424
 425 // The first entry in the PLT for an executable.
 426
 427 unsigned char Output_data_plt_x86_64::first_plt_entry[plt_entry_size] =
 428 {
 429   // From AMD64 ABI Draft 0.98, page 76
 430   0xff, 0x35,   // pushq contents of memory address
 431   0, 0, 0, 0,   // replaced with address of .got + 4
 432   0xff, 0x25,   // jmp indirect
 433   0, 0, 0, 0,   // replaced with address of .got + 8
 434   0x90, 0x90, 0x90, 0x90   // noop (x4)
 435 };
 436
 437 // Subsequent entries in the PLT for an executable.
 438
 439 unsigned char Output_data_plt_x86_64::plt_entry[plt_entry_size] =
 440 {
 441   // From AMD64 ABI Draft 0.98, page 76
 442   0xff, 0x25,   // jmpq indirect
 443   0, 0, 0, 0,   // replaced with address of symbol in .got
 444   0x68,         // pushq immediate
 445   0, 0, 0, 0,   // replaced with offset into relocation table
 446   0xe9,         // jmpq relative
 447   0, 0, 0, 0    // replaced with offset to start of .plt
 448 };
 449
 450 // Write out the PLT.  This uses the hand-coded instructions above,
 451 // and adjusts them as needed.  This is specified by the AMD64 ABI.
 452
 453 void
 454 Output_data_plt_x86_64::do_write(Output_file* of)
 455 {
 456   const off_t offset = this->offset();
 457   const off_t oview_size = this->data_size();
 458   unsigned char* const oview = of->get_output_view(offset, oview_size);
 459
 460   const off_t got_file_offset = this->got_plt_->offset();
 461   const off_t got_size = this->got_plt_->data_size();
 462   unsigned char* const got_view = of->get_output_view(got_file_offset,
 463                                                       got_size);
 464
 465   unsigned char* pov = oview;
 466
 467   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
 468   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 469
 470   memcpy(pov, first_plt_entry, plt_entry_size);
 471   if (!parameters->output_is_shared())
 472     {
 473       // We do a jmp relative to the PC at the end of this instruction.
 474       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 8
 475                                                   - (plt_address + 6));
 476       elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 16
 477                                         - (plt_address + 12));
 478     }
 479   pov += plt_entry_size;
 480
 481   unsigned char* got_pov = got_view;
 482
 483   memset(got_pov, 0, 24);
 484   got_pov += 24;
 485
 486   unsigned int plt_offset = plt_entry_size;
 487   unsigned int got_offset = 24;
 488   const unsigned int count = this->count_;
 489   for (unsigned int plt_index = 0;
 490        plt_index < count;
 491        ++plt_index,
 492          pov += plt_entry_size,
 493          got_pov += 8,
 494          plt_offset += plt_entry_size,
 495          got_offset += 8)
 496     {
 497       // Set and adjust the PLT entry itself.
 498       memcpy(pov, plt_entry, plt_entry_size);
 499       if (parameters->output_is_shared())
 500         // FIXME(csilvers): what's the right thing to write here?
 501         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
 502       else
 503         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 504                                                     (got_address + got_offset
 505                                                      - (plt_address + plt_offset
 506                                                         + 6)));
 507
 508       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_index);
 509       elfcpp::Swap<32, false>::writeval(pov + 12,
 510                                         - (plt_offset + plt_entry_size));
 511
 512       // Set the entry in the GOT.
 513       elfcpp::Swap<64, false>::writeval(got_pov, plt_address + plt_offset + 6);
 514     }
 515
 516   gold_assert(pov - oview == oview_size);
 517   gold_assert(got_pov - got_view == got_size);
 518
 519   of->write_output_view(offset, oview_size, oview);
 520   of->write_output_view(got_file_offset, got_size, got_view);
 521 }
 522
 523 // Create a PLT entry for a global symbol.
 524
 525 void
 526 Target_x86_64::make_plt_entry(Symbol_table* symtab, Layout* layout,
 527                               Symbol* gsym)
 528 {
 529   if (gsym->has_plt_offset())
 530     return;
 531
 532   if (this->plt_ == NULL)
 533     {
 534       // Create the GOT sections first.
 535       this->got_section(symtab, layout);
 536
 537       this->plt_ = new Output_data_plt_x86_64(layout, this->got_plt_);
 538       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 539                                       (elfcpp::SHF_ALLOC
 540                                        | elfcpp::SHF_EXECINSTR),
 541                                       this->plt_);
 542     }
 543
 544   this->plt_->add_entry(gsym);
 545 }
 546
 547 // Handle a relocation against a non-function symbol defined in a
 548 // dynamic object.  The traditional way to handle this is to generate
 549 // a COPY relocation to copy the variable at runtime from the shared
 550 // object into the executable's data segment.  However, this is
 551 // undesirable in general, as if the size of the object changes in the
 552 // dynamic object, the executable will no longer work correctly.  If
 553 // this relocation is in a writable section, then we can create a
 554 // dynamic reloc and the dynamic linker will resolve it to the correct
 555 // address at runtime.  However, we do not want do that if the
 556 // relocation is in a read-only section, as it would prevent the
 557 // readonly segment from being shared.  And if we have to eventually
 558 // generate a COPY reloc, then any dynamic relocations will be
 559 // useless.  So this means that if this is a writable section, we need
 560 // to save the relocation until we see whether we have to create a
 561 // COPY relocation for this symbol for any other relocation.
 562
 563 void
 564 Target_x86_64::copy_reloc(const General_options* options,
 565                           Symbol_table* symtab,
 566                           Layout* layout,
 567                           Sized_relobj<64, false>* object,
 568                           unsigned int data_shndx, Symbol* gsym,
 569                           const elfcpp::Rela<64, false>& rel)
 570 {
 571   Sized_symbol<64>* ssym;
 572   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(64) (gsym
 573                                                         SELECT_SIZE(64));
 574
 575   if (!Copy_relocs<64, false>::need_copy_reloc(options, object,
 576                                                data_shndx, ssym))
 577     {
 578       // So far we do not need a COPY reloc.  Save this relocation.
 579       // If it turns out that we never need a COPY reloc for this
 580       // symbol, then we will emit the relocation.
 581       if (this->copy_relocs_ == NULL)
 582         this->copy_relocs_ = new Copy_relocs<64, false>();
 583       this->copy_relocs_->save(ssym, object, data_shndx, rel);
 584     }
 585   else
 586     {
 587       // Allocate space for this symbol in the .bss section.
 588
 589       elfcpp::Elf_types<64>::Elf_WXword symsize = ssym->symsize();
 590
 591       // There is no defined way to determine the required alignment
 592       // of the symbol.  We pick the alignment based on the size.  We
 593       // set an arbitrary maximum of 256.
 594       unsigned int align;
 595       for (align = 1; align < 512; align <<= 1)
 596         if ((symsize & align) != 0)
 597           break;
 598
 599       if (this->dynbss_ == NULL)
 600         {
 601           this->dynbss_ = new Output_data_space(align);
 602           layout->add_output_section_data(".bss",
 603                                           elfcpp::SHT_NOBITS,
 604                                           (elfcpp::SHF_ALLOC
 605                                            | elfcpp::SHF_WRITE),
 606                                           this->dynbss_);
 607         }
 608
 609       Output_data_space* dynbss = this->dynbss_;
 610
 611       if (align > dynbss->addralign())
 612         dynbss->set_space_alignment(align);
 613
 614       off_t dynbss_size = dynbss->data_size();
 615       dynbss_size = align_address(dynbss_size, align);
 616       off_t offset = dynbss_size;
 617       dynbss->set_space_size(dynbss_size + symsize);
 618
 619       // Define the symbol in the .dynbss section.
 620       symtab->define_in_output_data(this, ssym->name(), ssym->version(),
 621                                     dynbss, offset, symsize, ssym->type(),
 622                                     ssym->binding(), ssym->visibility(),
 623                                     ssym->nonvis(), false, false);
 624
 625       // Add the COPY reloc.
 626       ssym->set_needs_dynsym_entry();
 627       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
 628       rel_dyn->add_global(ssym, elfcpp::R_X86_64_COPY, dynbss, offset, 0);
 629     }
 630 }
 631
 632
 633 // Optimize the TLS relocation type based on what we know about the
 634 // symbol.  IS_FINAL is true if the final address of this symbol is
 635 // known at link time.
 636
 637 unsigned int
 638 Target_x86_64::optimize_tls_reloc(bool is_final, int r_type)
 639 {
 640   // If we are generating a shared library, then we can't do anything
 641   // in the linker.
 642   if (parameters->output_is_shared())
 643     return r_type;
 644
 645   switch (r_type)
 646     {
 647     case elfcpp::R_X86_64_TLSGD:
 648     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // TODO(csilvers): correct?
 649     case elfcpp::R_X86_64_TLSDESC_CALL:  // TODO(csilvers): correct?
 650       // These are Global-Dynamic which permits fully general TLS
 651       // access.  Since we know that we are generating an executable,
 652       // we can convert this to Initial-Exec.  If we also know that
 653       // this is a local symbol, we can further switch to Local-Exec.
 654       if (is_final)
 655         return elfcpp::R_X86_64_TPOFF32;
 656       return elfcpp::R_X86_64_GOTTPOFF;     // used for Initial-exec
 657
 658     case elfcpp::R_X86_64_TLSLD:
 659       // This is Local-Dynamic, which refers to a local symbol in the
 660       // dynamic TLS block.  Since we know that we generating an
 661       // executable, we can switch to Local-Exec.
 662       return elfcpp::R_X86_64_TPOFF32;
 663
 664     case elfcpp::R_X86_64_GOTTPOFF:
 665       // These are Initial-Exec relocs which get the thread offset
 666       // from the GOT.  If we know that we are linking against the
 667       // local symbol, we can switch to Local-Exec, which links the
 668       // thread offset into the instruction.
 669       if (is_final)
 670         return elfcpp::R_X86_64_TPOFF32;
 671       return r_type;
 672
 673     case elfcpp::R_X86_64_TPOFF32:
 674       // When we already have Local-Exec, there is nothing further we
 675       // can do.
 676       return r_type;
 677
 678     default:
 679       gold_unreachable();
 680     }
 681 }
 682
 683 // Scan a relocation for a local symbol.
 684
 685 inline void
 686 Target_x86_64::Scan::local(const General_options&,
 687                            Symbol_table* symtab,
 688                            Layout* layout,
 689                            Target_x86_64* target,
 690                            Sized_relobj<64, false>* object,
 691                            unsigned int,
 692                            const elfcpp::Rela<64, false>&,
 693                            unsigned int r_type,
 694                            const elfcpp::Sym<64, false>&)
 695 {
 696   switch (r_type)
 697     {
 698     case elfcpp::R_X86_64_NONE:
 699     case elfcpp::R_386_GNU_VTINHERIT:
 700     case elfcpp::R_386_GNU_VTENTRY:
 701       break;
 702
 703     case elfcpp::R_X86_64_64:
 704     case elfcpp::R_X86_64_32:
 705     case elfcpp::R_X86_64_32S:
 706     case elfcpp::R_X86_64_16:
 707     case elfcpp::R_X86_64_8:
 708       // FIXME: If we are generating a shared object we need to copy
 709       // this relocation into the object.
 710       gold_assert(!parameters->output_is_shared());
 711       break;
 712
 713     case elfcpp::R_X86_64_PC64:
 714     case elfcpp::R_X86_64_PC32:
 715     case elfcpp::R_X86_64_PC16:
 716     case elfcpp::R_X86_64_PC8:
 717       break;
 718
 719     case elfcpp::R_X86_64_GOTPC32:  // TODO(csilvers): correct?
 720     case elfcpp::R_X86_64_GOTOFF64:
 721     case elfcpp::R_X86_64_GOTPC64:  // TODO(csilvers): correct?
 722     case elfcpp::R_X86_64_PLTOFF64:  // TODO(csilvers): correct?
 723       // We need a GOT section.
 724       target->got_section(symtab, layout);
 725       break;
 726
 727     case elfcpp::R_X86_64_COPY:
 728     case elfcpp::R_X86_64_GLOB_DAT:
 729     case elfcpp::R_X86_64_JUMP_SLOT:
 730     case elfcpp::R_X86_64_RELATIVE:
 731       // These are outstanding tls relocs, which are unexpected when linking
 732     case elfcpp::R_X86_64_TPOFF64:
 733     case elfcpp::R_X86_64_DTPMOD64:
 734     case elfcpp::R_X86_64_DTPOFF64:
 735     case elfcpp::R_X86_64_DTPOFF32:
 736     case elfcpp::R_X86_64_TLSDESC:
 737       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
 738               program_name, object->name().c_str(), r_type);
 739       gold_exit(false);
 740       break;
 741
 742       // These are initial tls relocs, which are expected when linking
 743     case elfcpp::R_X86_64_TLSGD:  // TODO(csilvers): correct?
 744     case elfcpp::R_X86_64_TLSLD:  // TODO(csilvers): correct?
 745     case elfcpp::R_X86_64_GOTTPOFF:  // TODO(csilvers): correct?
 746     case elfcpp::R_X86_64_TPOFF32:  // TODO(csilvers): correct?
 747     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // TODO(csilvers): correct?
 748     case elfcpp::R_X86_64_TLSDESC_CALL:  // TODO(csilvers): correct?
 749       {
 750         bool output_is_shared = parameters->output_is_shared();
 751         r_type = Target_x86_64::optimize_tls_reloc(!output_is_shared, r_type);
 752         switch (r_type)
 753           {
 754           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
 755             // FIXME: If generating a shared object, we need to copy
 756             // this relocation into the object.
 757             gold_assert(!output_is_shared);
 758             break;
 759
 760           case elfcpp::R_X86_64_GOTTPOFF:       // Initial-exec
 761           case elfcpp::R_X86_64_TLSGD:          // General Dynamic
 762           case elfcpp::R_X86_64_TLSLD:          // Local Dynamic
 763           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 764           case elfcpp::R_X86_64_TLSDESC_CALL:
 765             fprintf(stderr,
 766                     _("%s: %s: unsupported reloc %u against local symbol\n"),
 767                     program_name, object->name().c_str(), r_type);
 768             break;
 769           }
 770       }
 771       break;
 772
 773     case elfcpp::R_X86_64_GOT64:  // TODO(csilvers): correct?
 774     case elfcpp::R_X86_64_GOT32:
 775     case elfcpp::R_X86_64_GOTPCREL64:  // TODO(csilvers): correct?
 776     case elfcpp::R_X86_64_GOTPCREL:
 777     case elfcpp::R_X86_64_GOTPLT64:  // TODO(csilvers): correct?
 778     case elfcpp::R_X86_64_PLT32:
 779     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
 780     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
 781     default:
 782       fprintf(stderr, _("%s: %s: unsupported reloc %u against local symbol\n"),
 783               program_name, object->name().c_str(), r_type);
 784       break;
 785     }
 786 }
 787
 788
 789 // Scan a relocation for a global symbol.
 790
 791 inline void
 792 Target_x86_64::Scan::global(const General_options& options,
 793                             Symbol_table* symtab,
 794                             Layout* layout,
 795                             Target_x86_64* target,
 796                             Sized_relobj<64, false>* object,
 797                             unsigned int data_shndx,
 798                             const elfcpp::Rela<64, false>& reloc,
 799                             unsigned int r_type,
 800                             Symbol* gsym)
 801 {
 802   switch (r_type)
 803     {
 804     case elfcpp::R_X86_64_NONE:
 805     case elfcpp::R_386_GNU_VTINHERIT:
 806     case elfcpp::R_386_GNU_VTENTRY:
 807       break;
 808
 809     case elfcpp::R_X86_64_64:
 810     case elfcpp::R_X86_64_PC64:
 811     case elfcpp::R_X86_64_32:
 812     case elfcpp::R_X86_64_32S:
 813     case elfcpp::R_X86_64_PC32:
 814     case elfcpp::R_X86_64_16:
 815     case elfcpp::R_X86_64_PC16:
 816     case elfcpp::R_X86_64_8:
 817     case elfcpp::R_X86_64_PC8:
 818       // FIXME: If we are generating a shared object we may need to
 819       // copy this relocation into the object.  If this symbol is
 820       // defined in a shared object, we may need to copy this
 821       // relocation in order to avoid a COPY relocation.
 822       gold_assert(!parameters->output_is_shared());
 823
 824       if (gsym->is_from_dynobj())
 825         {
 826           // This symbol is defined in a dynamic object.  If it is a
 827           // function, we make a PLT entry.  Otherwise we need to
 828           // either generate a COPY reloc or copy this reloc.
 829           if (gsym->type() == elfcpp::STT_FUNC)
 830             {
 831               target->make_plt_entry(symtab, layout, gsym);
 832
 833               // If this is not a PC relative reference, then we may
 834               // be taking the address of the function.  In that case
 835               // we need to set the entry in the dynamic symbol table
 836               // to the address of the PLT entry.
 837               if (r_type != elfcpp::R_X86_64_PC64
 838                   && r_type != elfcpp::R_X86_64_PC32
 839                   && r_type != elfcpp::R_X86_64_PC16
 840                   && r_type != elfcpp::R_X86_64_PC8)
 841                 gsym->set_needs_dynsym_value();
 842             }
 843           else
 844             target->copy_reloc(&options, symtab, layout, object, data_shndx,
 845                                gsym, reloc);
 846         }
 847
 848       break;
 849
 850     case elfcpp::R_X86_64_GOT64:
 851     case elfcpp::R_X86_64_GOT32:
 852     case elfcpp::R_X86_64_GOTPCREL64:
 853     case elfcpp::R_X86_64_GOTPCREL:
 854     case elfcpp::R_X86_64_GOTPLT64:
 855       {
 856         // The symbol requires a GOT entry.
 857         Output_data_got<64, false>* got = target->got_section(symtab, layout);
 858         if (got->add_global(gsym))
 859           {
 860             // If this symbol is not fully resolved, we need to add a
 861             // dynamic relocation for it.
 862             if (!gsym->final_value_is_known())
 863               {
 864                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 865                 rel_dyn->add_global(gsym, elfcpp::R_X86_64_GLOB_DAT, got,
 866                                     gsym->got_offset(), 0);
 867               }
 868           }
 869       }
 870       break;
 871
 872     case elfcpp::R_X86_64_PLT32:
 873       // If the symbol is fully resolved, this is just a PC32 reloc.
 874       // Otherwise we need a PLT entry.
 875       if (gsym->final_value_is_known())
 876         break;
 877       target->make_plt_entry(symtab, layout, gsym);
 878       break;
 879
 880     case elfcpp::R_X86_64_GOTPC32:  // TODO(csilvers): correct?
 881     case elfcpp::R_X86_64_GOTOFF64:
 882     case elfcpp::R_X86_64_GOTPC64:  // TODO(csilvers): correct?
 883     case elfcpp::R_X86_64_PLTOFF64:  // TODO(csilvers): correct?
 884       // We need a GOT section.
 885       target->got_section(symtab, layout);
 886       break;
 887
 888     case elfcpp::R_X86_64_COPY:
 889     case elfcpp::R_X86_64_GLOB_DAT:
 890     case elfcpp::R_X86_64_JUMP_SLOT:
 891     case elfcpp::R_X86_64_RELATIVE:
 892       // These are outstanding tls relocs, which are unexpected when linking
 893     case elfcpp::R_X86_64_TPOFF64:
 894     case elfcpp::R_X86_64_DTPMOD64:
 895     case elfcpp::R_X86_64_DTPOFF64:
 896     case elfcpp::R_X86_64_DTPOFF32:
 897     case elfcpp::R_X86_64_TLSDESC:
 898       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
 899               program_name, object->name().c_str(), r_type);
 900       gold_exit(false);
 901       break;
 902
 903       // These are initial tls relocs, which are expected for global()
 904     case elfcpp::R_X86_64_TLSGD:  // TODO(csilvers): correct?
 905     case elfcpp::R_X86_64_TLSLD:  // TODO(csilvers): correct?
 906     case elfcpp::R_X86_64_GOTTPOFF:  // TODO(csilvers): correct?
 907     case elfcpp::R_X86_64_TPOFF32:  // TODO(csilvers): correct?
 908     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // TODO(csilvers): correct?
 909     case elfcpp::R_X86_64_TLSDESC_CALL:  // TODO(csilvers): correct?
 910       {
 911         const bool is_final = gsym->final_value_is_known();
 912         r_type = Target_x86_64::optimize_tls_reloc(is_final, r_type);
 913         switch (r_type)
 914           {
 915           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
 916             // FIXME: If generating a shared object, we need to copy
 917             // this relocation into the object.
 918             gold_assert(!parameters->output_is_shared());
 919             break;
 920
 921           case elfcpp::R_X86_64_GOTTPOFF:       // Initial-exec
 922           case elfcpp::R_X86_64_TLSGD:          // General Dynamic
 923           case elfcpp::R_X86_64_TLSLD:          // Local Dynamic
 924           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 925           case elfcpp::R_X86_64_TLSDESC_CALL:
 926             fprintf(stderr,
 927                     _("%s: %s: unsupported reloc %u "
 928                       "against global symbol %s\n"),
 929                     program_name, object->name().c_str(), r_type,
 930                     gsym->name());
 931             break;
 932           }
 933       }
 934       break;
 935
 936     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
 937     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
 938     default:
 939       fprintf(stderr,
 940               _("%s: %s: unsupported reloc %u against global symbol %s\n"),
 941               program_name, object->name().c_str(), r_type, gsym->name());
 942       break;
 943     }
 944 }
 945
 946 // Scan relocations for a section.
 947
 948 void
 949 Target_x86_64::scan_relocs(const General_options& options,
 950                            Symbol_table* symtab,
 951                            Layout* layout,
 952                            Sized_relobj<64, false>* object,
 953                            unsigned int data_shndx,
 954                            unsigned int sh_type,
 955                            const unsigned char* prelocs,
 956                            size_t reloc_count,
 957                            size_t local_symbol_count,
 958                            const unsigned char* plocal_symbols,
 959                            Symbol** global_symbols)
 960 {
 961   if (sh_type == elfcpp::SHT_REL)
 962     {
 963       fprintf(stderr, _("%s: %s: unsupported REL reloc section\n"),
 964               program_name, object->name().c_str());
 965       gold_exit(false);
 966     }
 967
 968   gold::scan_relocs<64, false, Target_x86_64, elfcpp::SHT_RELA,
 969       Target_x86_64::Scan>(
 970     options,
 971     symtab,
 972     layout,
 973     this,
 974     object,
 975     data_shndx,
 976     prelocs,
 977     reloc_count,
 978     local_symbol_count,
 979     plocal_symbols,
 980     global_symbols);
 981 }
 982
 983 // Finalize the sections.
 984
 985 void
 986 Target_x86_64::do_finalize_sections(Layout* layout)
 987 {
 988   // Fill in some more dynamic tags.
 989   Output_data_dynamic* const odyn = layout->dynamic_data();
 990   if (odyn != NULL)
 991     {
 992       if (this->got_plt_ != NULL)
 993         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
 994
 995       if (this->plt_ != NULL)
 996         {
 997           const Output_data* od = this->plt_->rel_plt();
 998           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
 999           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1000           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_RELA);
1001         }
1002
1003       if (this->rel_dyn_ != NULL)
1004         {
1005           const Output_data* od = this->rel_dyn_;
1006           odyn->add_section_address(elfcpp::DT_RELA, od);
1007           odyn->add_section_size(elfcpp::DT_RELASZ, od);
1008           odyn->add_constant(elfcpp::DT_RELAENT,
1009                              elfcpp::Elf_sizes<64>::rela_size);
1010         }
1011
1012       if (!parameters->output_is_shared())
1013         {
1014           // The value of the DT_DEBUG tag is filled in by the dynamic
1015           // linker at run time, and used by the debugger.
1016           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1017         }
1018     }
1019
1020   // Emit any relocs we saved in an attempt to avoid generating COPY
1021   // relocs.
1022   if (this->copy_relocs_ == NULL)
1023     return;
1024   if (this->copy_relocs_->any_to_emit())
1025     {
1026       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1027       this->copy_relocs_->emit(rel_dyn);
1028     }
1029   delete this->copy_relocs_;
1030   this->copy_relocs_ = NULL;
1031 }
1032
1033 // Perform a relocation.
1034
1035 inline bool
1036 Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo,
1037                                   Target_x86_64* target,
1038                                   size_t relnum,
1039                                   const elfcpp::Rela<64, false>& rel,
1040                                   unsigned int r_type,
1041                                   const Sized_symbol<64>* gsym,
1042                                   const Symbol_value<64>* psymval,
1043                                   unsigned char* view,
1044                                   elfcpp::Elf_types<64>::Elf_Addr address,
1045                                   off_t view_size)
1046 {
1047   if (this->skip_call_tls_get_addr_)
1048     {
1049       if (r_type != elfcpp::R_X86_64_PLT32
1050           || gsym == NULL
1051           || strcmp(gsym->name(), "___tls_get_addr") != 0)
1052         {
1053           fprintf(stderr, _("%s: %s: missing expected TLS relocation\n"),
1054                   program_name,
1055                   relinfo->location(relnum, rel.get_r_offset()).c_str());
1056           gold_exit(false);
1057         }
1058
1059       this->skip_call_tls_get_addr_ = false;
1060
1061       return false;
1062     }
1063
1064   // Pick the value to use for symbols defined in shared objects.
1065   Symbol_value<64> symval;
1066   if (gsym != NULL && gsym->is_from_dynobj() && gsym->has_plt_offset())
1067     {
1068       symval.set_output_value(target->plt_section()->address()
1069                               + gsym->plt_offset());
1070       psymval = &symval;
1071     }
1072
1073   const Sized_relobj<64, false>* object = relinfo->object;
1074   const elfcpp::Elf_Xword addend = rel.get_r_addend();
1075
1076   switch (r_type)
1077     {
1078     case elfcpp::R_X86_64_NONE:
1079     case elfcpp::R_386_GNU_VTINHERIT:
1080     case elfcpp::R_386_GNU_VTENTRY:
1081       break;
1082
1083     case elfcpp::R_X86_64_64:
1084       Relocate_functions<64, false>::rela64(view, object, psymval, addend);
1085       break;
1086
1087     case elfcpp::R_X86_64_PC64:
1088       Relocate_functions<64, false>::pcrela64(view, object, psymval, addend,
1089                                               address);
1090       break;
1091
1092     case elfcpp::R_X86_64_32:
1093       // FIXME: we need to verify that value + addend fits into 32 bits:
1094       //    uint64_t x = value + addend;
1095       //    x == static_cast<uint64_t>(static_cast<uint32_t>(x))
1096       // Likewise for other <=32-bit relocations (but see R_X86_64_32S).
1097       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1098       break;
1099
1100     case elfcpp::R_X86_64_32S:
1101       // FIXME: we need to verify that value + addend fits into 32 bits:
1102       //    int64_t x = value + addend;   // note this quantity is signed!
1103       //    x == static_cast<int64_t>(static_cast<int32_t>(x))
1104       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1105       break;
1106
1107     case elfcpp::R_X86_64_PC32:
1108       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1109                                               address);
1110       break;
1111
1112     case elfcpp::R_X86_64_16:
1113       Relocate_functions<64, false>::rela16(view, object, psymval, addend);
1114       break;
1115
1116     case elfcpp::R_X86_64_PC16:
1117       Relocate_functions<64, false>::pcrela16(view, object, psymval, addend,
1118                                               address);
1119       break;
1120
1121     case elfcpp::R_X86_64_8:
1122       Relocate_functions<64, false>::rela8(view, object, psymval, addend);
1123       break;
1124
1125     case elfcpp::R_X86_64_PC8:
1126       Relocate_functions<64, false>::pcrela8(view, object, psymval, addend,
1127                                              address);
1128       break;
1129
1130     case elfcpp::R_X86_64_PLT32:
1131       gold_assert(gsym->has_plt_offset()
1132                   || gsym->final_value_is_known());
1133       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1134                                               address);
1135       break;
1136
1137     case elfcpp::R_X86_64_GOT32:
1138       // Local GOT offsets not yet supported.
1139       gold_assert(gsym);
1140       gold_assert(gsym->has_got_offset());
1141       Relocate_functions<64, false>::rela32(view, gsym->got_offset(), addend);
1142       break;
1143
1144     case elfcpp::R_X86_64_GOTPC32:
1145       {
1146         gold_assert(gsym);
1147         elfcpp::Elf_types<64>::Elf_Addr value;
1148         value = target->got_section(NULL, NULL)->address();
1149         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1150       }
1151       break;
1152
1153     case elfcpp::R_X86_64_GOT64:
1154       // The ABI doc says "Like GOT64, but indicates a PLT entry is needed."
1155       // Since we always add a PLT entry, this is equivalent.
1156     case elfcpp::R_X86_64_GOTPLT64:  // TODO(csilvers): correct?
1157       // Local GOT offsets not yet supported.
1158       gold_assert(gsym);
1159       gold_assert(gsym->has_got_offset());
1160       Relocate_functions<64, false>::rela64(view, gsym->got_offset(), addend);
1161       break;
1162
1163     case elfcpp::R_X86_64_GOTPC64:
1164       {
1165         gold_assert(gsym);
1166         elfcpp::Elf_types<64>::Elf_Addr value;
1167         value = target->got_section(NULL, NULL)->address();
1168         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1169       }
1170       break;
1171
1172     case elfcpp::R_X86_64_GOTOFF64:
1173       {
1174         elfcpp::Elf_types<64>::Elf_Addr value;
1175         value = (psymval->value(object, 0)
1176                  - target->got_section(NULL, NULL)->address());
1177         Relocate_functions<64, false>::rela64(view, value, addend);
1178       }
1179       break;
1180
1181     case elfcpp::R_X86_64_GOTPCREL:
1182       {
1183         // Local GOT offsets not yet supported.
1184         gold_assert(gsym);
1185         gold_assert(gsym->has_got_offset());
1186         elfcpp::Elf_types<64>::Elf_Addr value;
1187         value = (target->got_section(NULL, NULL)->address()
1188                  + gsym->got_offset());
1189         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1190       }
1191       break;
1192
1193     case elfcpp::R_X86_64_GOTPCREL64:
1194       {
1195         // Local GOT offsets not yet supported.
1196         gold_assert(gsym);
1197         gold_assert(gsym->has_got_offset());
1198         elfcpp::Elf_types<64>::Elf_Addr value;
1199         value = (target->got_section(NULL, NULL)->address()
1200                  + gsym->got_offset());
1201         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1202       }
1203       break;
1204
1205     case elfcpp::R_X86_64_COPY:
1206     case elfcpp::R_X86_64_GLOB_DAT:
1207     case elfcpp::R_X86_64_JUMP_SLOT:
1208     case elfcpp::R_X86_64_RELATIVE:
1209       // These are outstanding tls relocs, which are unexpected when linking
1210     case elfcpp::R_X86_64_TPOFF64:
1211     case elfcpp::R_X86_64_DTPMOD64:
1212     case elfcpp::R_X86_64_DTPOFF64:
1213     case elfcpp::R_X86_64_DTPOFF32:
1214     case elfcpp::R_X86_64_TLSDESC:
1215       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
1216               program_name,
1217               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1218               r_type);
1219       gold_exit(false);
1220       break;
1221
1222       // These are initial tls relocs, which are expected when linking
1223     case elfcpp::R_X86_64_TLSGD:  // TODO(csilvers): correct?
1224     case elfcpp::R_X86_64_TLSLD:  // TODO(csilvers): correct?
1225     case elfcpp::R_X86_64_GOTTPOFF:  // TODO(csilvers): correct?
1226     case elfcpp::R_X86_64_TPOFF32:  // TODO(csilvers): correct?
1227     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // TODO(csilvers): correct?
1228     case elfcpp::R_X86_64_TLSDESC_CALL:  // TODO(csilvers): correct?
1229       this->relocate_tls(relinfo, relnum, rel, r_type, gsym, psymval, view,
1230                          address, view_size);
1231       break;
1232
1233     case elfcpp::R_X86_64_SIZE32:  // TODO(csilvers): correct?
1234     case elfcpp::R_X86_64_SIZE64:  // TODO(csilvers): correct?
1235     case elfcpp::R_X86_64_PLTOFF64:  // TODO(csilvers): implement me!
1236     default:
1237       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1238               program_name,
1239               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1240               r_type);
1241       gold_exit(false);
1242       break;
1243     }
1244
1245   return true;
1246 }
1247
1248 // Perform a TLS relocation.
1249
1250 inline void
1251 Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo,
1252                                       size_t relnum,
1253                                       const elfcpp::Rela<64, false>& rel,
1254                                       unsigned int r_type,
1255                                       const Sized_symbol<64>* gsym,
1256                                       const Symbol_value<64>* psymval,
1257                                       unsigned char* view,
1258                                       elfcpp::Elf_types<64>::Elf_Addr,
1259                                       off_t view_size)
1260 {
1261   Output_segment* tls_segment = relinfo->layout->tls_segment();
1262   if (tls_segment == NULL)
1263     {
1264       fprintf(stderr, _("%s: %s: TLS reloc but no TLS segment\n"),
1265               program_name,
1266               relinfo->location(relnum, rel.get_r_offset()).c_str());
1267       gold_exit(false);
1268     }
1269
1270   elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0);
1271
1272   const bool is_final = (gsym == NULL
1273                          ? !parameters->output_is_shared()
1274                          : gsym->final_value_is_known());
1275   const unsigned int opt_r_type =
1276     Target_x86_64::optimize_tls_reloc(is_final, r_type);
1277   switch (r_type)
1278     {
1279     case elfcpp::R_X86_64_TPOFF32:   // Local-exec reloc
1280       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1281       Relocate_functions<64, false>::rel32(view, value);
1282       break;
1283
1284     case elfcpp::R_X86_64_GOTTPOFF:  // Initial-exec reloc
1285       if (opt_r_type == elfcpp::R_X86_64_TPOFF32)
1286         {
1287           Target_x86_64::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1288                                                 rel, r_type, value, view,
1289                                                 view_size);
1290           break;
1291         }
1292       fprintf(stderr, _("%s: %s: unsupported reloc type %u\n"),
1293               program_name,
1294               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1295               r_type);
1296       gold_exit(false);
1297       break;
1298
1299     case elfcpp::R_X86_64_TLSGD:
1300       if (opt_r_type == elfcpp::R_X86_64_TPOFF32)
1301         {
1302           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1303                              rel, r_type, value, view,
1304                              view_size);
1305           break;
1306         }
1307       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1308               program_name,
1309               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1310               r_type);
1311       gold_exit(false);
1312       break;
1313
1314     case elfcpp::R_X86_64_TLSLD:
1315       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1316               program_name,
1317               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1318               r_type);
1319       gold_exit(false);
1320       break;
1321     }
1322 }
1323
1324 // Do a relocation in which we convert a TLS Initial-Exec to a
1325 // Local-Exec.
1326 // TODO(csilvers): verify this is right.
1327
1328 inline void
1329 Target_x86_64::Relocate::tls_ie_to_le(const Relocate_info<64, false>* relinfo,
1330                                       size_t relnum,
1331                                       Output_segment* tls_segment,
1332                                       const elfcpp::Rela<64, false>& rel,
1333                                       unsigned int,
1334                                       elfcpp::Elf_types<64>::Elf_Addr value,
1335                                       unsigned char* view,
1336                                       off_t view_size)
1337 {
1338   // We have to actually change the instructions, which means that we
1339   // need to examine the opcodes to figure out which instruction we
1340   // are looking at.
1341
1342   // movl %gs:XX,%eax  ==>  movl $YY,%eax
1343   // movl %gs:XX,%reg  ==>  movl $YY,%reg
1344   // addl %gs:XX,%reg  ==>  addl $YY,%reg
1345   Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, -1);
1346   Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, 4);
1347
1348   unsigned char op1 = view[-1];
1349   if (op1 == 0xa1)
1350     {
1351       // movl XX,%eax  ==>  movl $YY,%eax
1352       view[-1] = 0xb8;
1353     }
1354   else
1355     {
1356       Target_x86_64::Relocate::check_range(relinfo, relnum, rel,
1357                                            view_size, -2);
1358
1359       unsigned char op2 = view[-2];
1360       if (op2 == 0x8b)
1361         {
1362           // movl XX,%reg  ==>  movl $YY,%reg
1363           Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1364                                              (op1 & 0xc7) == 0x05);
1365           view[-2] = 0xc7;
1366           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1367         }
1368       else if (op2 == 0x03)
1369         {
1370           // addl XX,%reg  ==>  addl $YY,%reg
1371           Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1372                                              (op1 & 0xc7) == 0x05);
1373           view[-2] = 0x81;
1374           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1375         }
1376       else
1377         Target_x86_64::Relocate::check_tls(relinfo, relnum, rel, 0);
1378     }
1379
1380   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1381   Relocate_functions<64, false>::rel32(view, value);
1382 }
1383
1384 // Do a relocation in which we convert a TLS Global-Dynamic to a
1385 // Local-Exec.
1386 // TODO(csilvers): verify this is right.
1387
1388 inline void
1389 Target_x86_64::Relocate::tls_gd_to_le(const Relocate_info<64, false>* relinfo,
1390                                       size_t relnum,
1391                                       Output_segment* tls_segment,
1392                                       const elfcpp::Rela<64, false>& rel,
1393                                       unsigned int,
1394                                       elfcpp::Elf_types<64>::Elf_Addr value,
1395                                       unsigned char* view,
1396                                       off_t view_size)
1397 {
1398   // leal foo(,%reg,1),%eax; call ___tls_get_addr
1399   //  ==> movl %gs,0,%eax; subl $foo@tpoff,%eax
1400   // leal foo(%reg),%eax; call ___tls_get_addr
1401   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1402
1403   Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, -2);
1404   Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, 9);
1405
1406   unsigned char op1 = view[-1];
1407   unsigned char op2 = view[-2];
1408
1409   Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1410                                      op2 == 0x8d || op2 == 0x04);
1411   Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1412                                      view[4] == 0xe8);
1413
1414   int roff = 5;
1415
1416   if (op2 == 0x04)
1417     {
1418       Target_x86_64::Relocate::check_range(relinfo, relnum, rel, view_size, -3);
1419       Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1420                                          view[-3] == 0x8d);
1421       Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1422                                          ((op1 & 0xc7) == 0x05
1423                                           && op1 != (4 << 3)));
1424       memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1425     }
1426   else
1427     {
1428       Target_x86_64::Relocate::check_tls(relinfo, relnum, rel,
1429                                          (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1430       if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
1431           && view[9] == 0x90)
1432         {
1433           // There is a trailing nop.  Use the size byte subl.
1434           memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1435           roff = 6;
1436         }
1437       else
1438         {
1439           // Use the five byte subl.
1440           memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1441         }
1442     }
1443
1444   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1445   Relocate_functions<64, false>::rel32(view + roff, value);
1446
1447   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1448   // We can skip it.
1449   this->skip_call_tls_get_addr_ = true;
1450 }
1451
1452 // Check the range for a TLS relocation.
1453
1454 inline void
1455 Target_x86_64::Relocate::check_range(const Relocate_info<64, false>* relinfo,
1456                                      size_t relnum,
1457                                      const elfcpp::Rela<64, false>& rel,
1458                                      off_t view_size, off_t off)
1459 {
1460   off_t offset = rel.get_r_offset() + off;
1461   if (offset < 0 || offset > view_size)
1462     {
1463       fprintf(stderr, _("%s: %s: TLS relocation out of range\n"),
1464               program_name,
1465               relinfo->location(relnum, rel.get_r_offset()).c_str());
1466       gold_exit(false);
1467     }
1468 }
1469
1470 // Check the validity of a TLS relocation.  This is like assert.
1471
1472 inline void
1473 Target_x86_64::Relocate::check_tls(const Relocate_info<64, false>* relinfo,
1474                                    size_t relnum,
1475                                    const elfcpp::Rela<64, false>& rel,
1476                                    bool valid)
1477 {
1478   if (!valid)
1479     {
1480       fprintf(stderr,
1481               _("%s: %s: TLS relocation against invalid instruction\n"),
1482               program_name,
1483               relinfo->location(relnum, rel.get_r_offset()).c_str());
1484       gold_exit(false);
1485     }
1486 }
1487
1488 // Relocate section data.
1489
1490 void
1491 Target_x86_64::relocate_section(const Relocate_info<64, false>* relinfo,
1492                                 unsigned int sh_type,
1493                                 const unsigned char* prelocs,
1494                                 size_t reloc_count,
1495                                 unsigned char* view,
1496                                 elfcpp::Elf_types<64>::Elf_Addr address,
1497                                 off_t view_size)
1498 {
1499   gold_assert(sh_type == elfcpp::SHT_RELA);
1500
1501   gold::relocate_section<64, false, Target_x86_64, elfcpp::SHT_RELA,
1502                          Target_x86_64::Relocate>(
1503     relinfo,
1504     this,
1505     prelocs,
1506     reloc_count,
1507     view,
1508     address,
1509     view_size);
1510 }
1511
1512 // Return the value to use for a dynamic which requires special
1513 // treatment.  This is how we support equality comparisons of function
1514 // pointers across shared library boundaries, as described in the
1515 // processor specific ABI supplement.
1516
1517 uint64_t
1518 Target_x86_64::do_dynsym_value(const Symbol* gsym) const
1519 {
1520   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1521   return this->plt_section()->address() + gsym->plt_offset();
1522 }
1523
1524 // Return a string used to fill a code section with nops to take up
1525 // the specified length.
1526
1527 std::string
1528 Target_x86_64::do_code_fill(off_t length)
1529 {
1530   if (length >= 16)
1531     {
1532       // Build a jmpq instruction to skip over the bytes.
1533       unsigned char jmp[5];
1534       jmp[0] = 0xe9;
1535       elfcpp::Swap_unaligned<64, false>::writeval(jmp + 1, length - 5);
1536       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1537               + std::string(length - 5, '\0'));
1538     }
1539
1540   // Nop sequences of various lengths.
1541   const char nop1[1] = { 0x90 };                   // nop
1542   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1543   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1544   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1545   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1546                          0x00 };                   // leal 0(%esi,1),%esi
1547   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1548                          0x00, 0x00 };
1549   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1550                          0x00, 0x00, 0x00 };
1551   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1552                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1553   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1554                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1555                          0x00 };
1556   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1557                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1558                            0x00, 0x00 };
1559   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1560                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1561                            0x00, 0x00, 0x00 };
1562   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1563                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1564                            0x00, 0x00, 0x00, 0x00 };
1565   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1566                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1567                            0x27, 0x00, 0x00, 0x00,
1568                            0x00 };
1569   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1570                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1571                            0xbc, 0x27, 0x00, 0x00,
1572                            0x00, 0x00 };
1573   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1574                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1575                            0x90, 0x90, 0x90, 0x90,
1576                            0x90, 0x90, 0x90 };
1577
1578   const char* nops[16] = {
1579     NULL,
1580     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1581     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1582   };
1583
1584   return std::string(nops[length], length);
1585 }
1586
1587 // The selector for x86_64 object files.
1588
1589 class Target_selector_x86_64 : public Target_selector
1590 {
1591 public:
1592   Target_selector_x86_64()
1593     : Target_selector(elfcpp::EM_X86_64, 64, false)
1594   { }
1595
1596   Target*
1597   recognize(int machine, int osabi, int abiversion);
1598
1599  private:
1600   Target_x86_64* target_;
1601 };
1602
1603 // Recognize an x86_64 object file when we already know that the machine
1604 // number is EM_X86_64.
1605
1606 Target*
1607 Target_selector_x86_64::recognize(int, int, int)
1608 {
1609   if (this->target_ == NULL)
1610     this->target_ = new Target_x86_64();
1611   return this->target_;
1612 }
1613
1614 Target_selector_x86_64 target_selector_x86_64;
1615
1616 } // End anonymous namespace.