gold/x86_64.cc

   1 // x86_64.cc -- x86_64 target support for gold.
   2
   3 // Copyright 2006, 2007, Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or
   9 // modify it under the terms of the GNU Library General Public License
  10 // as published by the Free Software Foundation; either version 2, or
  11 // (at your option) any later version.
  12
  13 // In addition to the permissions in the GNU Library General Public
  14 // License, the Free Software Foundation gives you unlimited
  15 // permission to link the compiled version of this file into
  16 // combinations with other programs, and to distribute those
  17 // combinations without any restriction coming from the use of this
  18 // file.  (The Library Public License restrictions do apply in other
  19 // respects; for example, they cover modification of the file, and
  20 /// distribution when not linked into a combined executable.)
  21
  22 // This program is distributed in the hope that it will be useful, but
  23 // WITHOUT ANY WARRANTY; without even the implied warranty of
  24 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  25 // Library General Public License for more details.
  26
  27 // You should have received a copy of the GNU Library General Public
  28 // License along with this program; if not, write to the Free Software
  29 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
  30 // 02110-1301, USA.
  31
  32 #include "gold.h"
  33
  34 #include <cstring>
  35
  36 #include "elfcpp.h"
  37 #include "parameters.h"
  38 #include "reloc.h"
  39 #include "x86_64.h"
  40 #include "object.h"
  41 #include "symtab.h"
  42 #include "layout.h"
  43 #include "output.h"
  44 #include "target.h"
  45 #include "target-reloc.h"
  46 #include "target-select.h"
  47 #include "tls.h"
  48
  49 namespace
  50 {
  51
  52 using namespace gold;
  53
  54 class Output_data_plt_x86_64;
  55
  56 // The x86_64 target class.
  57 // See the ABI at
  58 //   http://www.x86-64.org/documentation/abi.pdf
  59 // TLS info comes from
  60 //   http://people.redhat.com/drepper/tls.pdf
  61 //   http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
  62
  63 class Target_x86_64 : public Sized_target<64, false>
  64 {
  65  public:
  66   // In the x86_64 ABI (p 68), it says "The AMD64 ABI architectures
  67   // uses only Elf64_Rela relocation entries with explicit addends."
  68   typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
  69
  70   Target_x86_64()
  71     : Sized_target<64, false>(&x86_64_info),
  72       got_(NULL), plt_(NULL), got_plt_(NULL), rela_dyn_(NULL),
  73       copy_relocs_(NULL), dynbss_(NULL)
  74   { }
  75
  76   // Scan the relocations to look for symbol adjustments.
  77   void
  78   scan_relocs(const General_options& options,
  79               Symbol_table* symtab,
  80               Layout* layout,
  81               Sized_relobj<64, false>* object,
  82               unsigned int data_shndx,
  83               unsigned int sh_type,
  84               const unsigned char* prelocs,
  85               size_t reloc_count,
  86               size_t local_symbol_count,
  87               const unsigned char* plocal_symbols,
  88               Symbol** global_symbols);
  89
  90   // Finalize the sections.
  91   void
  92   do_finalize_sections(Layout*);
  93
  94   // Return the value to use for a dynamic which requires special
  95   // treatment.
  96   uint64_t
  97   do_dynsym_value(const Symbol*) const;
  98
  99   // Relocate a section.
 100   void
 101   relocate_section(const Relocate_info<64, false>*,
 102                    unsigned int sh_type,
 103                    const unsigned char* prelocs,
 104                    size_t reloc_count,
 105                    unsigned char* view,
 106                    elfcpp::Elf_types<64>::Elf_Addr view_address,
 107                    off_t view_size);
 108
 109   // Return a string used to fill a code section with nops.
 110   std::string
 111   do_code_fill(off_t length);
 112
 113  private:
 114   // The class which scans relocations.
 115   struct Scan
 116   {
 117     inline void
 118     local(const General_options& options, Symbol_table* symtab,
 119           Layout* layout, Target_x86_64* target,
 120           Sized_relobj<64, false>* object,
 121           unsigned int data_shndx,
 122           const elfcpp::Rela<64, false>& reloc, unsigned int r_type,
 123           const elfcpp::Sym<64, false>& lsym);
 124
 125     inline void
 126     global(const General_options& options, Symbol_table* symtab,
 127            Layout* layout, Target_x86_64* target,
 128            Sized_relobj<64, false>* object,
 129            unsigned int data_shndx,
 130            const elfcpp::Rela<64, false>& reloc, unsigned int r_type,
 131            Symbol* gsym);
 132
 133     static void
 134     unsupported_reloc_local(Sized_relobj<64, false>*, unsigned int r_type);
 135
 136     static void
 137     unsupported_reloc_global(Sized_relobj<64, false>*, unsigned int r_type,
 138                              Symbol*);
 139   };
 140
 141   // The class which implements relocation.
 142   class Relocate
 143   {
 144    public:
 145     Relocate()
 146       : skip_call_tls_get_addr_(false)
 147     { }
 148
 149     ~Relocate()
 150     {
 151       if (this->skip_call_tls_get_addr_)
 152         {
 153           // FIXME: This needs to specify the location somehow.
 154           gold_error(_("missing expected TLS relocation"));
 155         }
 156     }
 157
 158     // Do a relocation.  Return false if the caller should not issue
 159     // any warnings about this relocation.
 160     inline bool
 161     relocate(const Relocate_info<64, false>*, Target_x86_64*, size_t relnum,
 162              const elfcpp::Rela<64, false>&,
 163              unsigned int r_type, const Sized_symbol<64>*,
 164              const Symbol_value<64>*,
 165              unsigned char*, elfcpp::Elf_types<64>::Elf_Addr,
 166              off_t);
 167
 168    private:
 169     // Do a TLS relocation.
 170     inline void
 171     relocate_tls(const Relocate_info<64, false>*, size_t relnum,
 172                  const elfcpp::Rela<64, false>&,
 173                  unsigned int r_type, const Sized_symbol<64>*,
 174                  const Symbol_value<64>*,
 175                  unsigned char*, elfcpp::Elf_types<64>::Elf_Addr, off_t);
 176
 177     // Do a TLS General-Dynamic to Local-Exec transition.
 178     inline void
 179     tls_gd_to_le(const Relocate_info<64, false>*, size_t relnum,
 180                  Output_segment* tls_segment,
 181                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 182                  elfcpp::Elf_types<64>::Elf_Addr value,
 183                  unsigned char* view,
 184                  off_t view_size);
 185
 186     // Do a TLS Local-Dynamic to Local-Exec transition.
 187     inline void
 188     tls_ld_to_le(const Relocate_info<64, false>*, size_t relnum,
 189                  Output_segment* tls_segment,
 190                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 191                  elfcpp::Elf_types<64>::Elf_Addr value,
 192                  unsigned char* view,
 193                  off_t view_size);
 194
 195     // Do a TLS Initial-Exec to Local-Exec transition.
 196     static inline void
 197     tls_ie_to_le(const Relocate_info<64, false>*, size_t relnum,
 198                  Output_segment* tls_segment,
 199                  const elfcpp::Rela<64, false>&, unsigned int r_type,
 200                  elfcpp::Elf_types<64>::Elf_Addr value,
 201                  unsigned char* view,
 202                  off_t view_size);
 203
 204     // This is set if we should skip the next reloc, which should be a
 205     // PLT32 reloc against ___tls_get_addr.
 206     bool skip_call_tls_get_addr_;
 207   };
 208
 209   // Adjust TLS relocation type based on the options and whether this
 210   // is a local symbol.
 211   static tls::Tls_optimization
 212   optimize_tls_reloc(bool is_final, int r_type);
 213
 214   // Get the GOT section, creating it if necessary.
 215   Output_data_got<64, false>*
 216   got_section(Symbol_table*, Layout*);
 217
 218   // Create a PLT entry for a global symbol.
 219   void
 220   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 221
 222   // Get the PLT section.
 223   Output_data_plt_x86_64*
 224   plt_section() const
 225   {
 226     gold_assert(this->plt_ != NULL);
 227     return this->plt_;
 228   }
 229
 230   // Get the dynamic reloc section, creating it if necessary.
 231   Reloc_section*
 232   rela_dyn_section(Layout*);
 233
 234   // Copy a relocation against a global symbol.
 235   void
 236   copy_reloc(const General_options*, Symbol_table*, Layout*,
 237              Sized_relobj<64, false>*, unsigned int,
 238              Symbol*, const elfcpp::Rela<64, false>&);
 239
 240   // Information about this specific target which we pass to the
 241   // general Target structure.
 242   static const Target::Target_info x86_64_info;
 243
 244   // The GOT section.
 245   Output_data_got<64, false>* got_;
 246   // The PLT section.
 247   Output_data_plt_x86_64* plt_;
 248   // The GOT PLT section.
 249   Output_data_space* got_plt_;
 250   // The dynamic reloc section.
 251   Reloc_section* rela_dyn_;
 252   // Relocs saved to avoid a COPY reloc.
 253   Copy_relocs<64, false>* copy_relocs_;
 254   // Space for variables copied with a COPY reloc.
 255   Output_data_space* dynbss_;
 256 };
 257
 258 const Target::Target_info Target_x86_64::x86_64_info =
 259 {
 260   64,                   // size
 261   false,                // is_big_endian
 262   elfcpp::EM_X86_64,    // machine_code
 263   false,                // has_make_symbol
 264   false,                // has_resolve
 265   true,                 // has_code_fill
 266   true,                 // is_default_stack_executable
 267   "/lib/ld64.so.1",     // program interpreter
 268   0x400000,             // default_text_segment_address
 269   0x1000,               // abi_pagesize
 270   0x1000                // common_pagesize
 271 };
 272
 273 // Get the GOT section, creating it if necessary.
 274
 275 Output_data_got<64, false>*
 276 Target_x86_64::got_section(Symbol_table* symtab, Layout* layout)
 277 {
 278   if (this->got_ == NULL)
 279     {
 280       gold_assert(symtab != NULL && layout != NULL);
 281
 282       this->got_ = new Output_data_got<64, false>();
 283
 284       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 285                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 286                                       this->got_);
 287
 288       // The old GNU linker creates a .got.plt section.  We just
 289       // create another set of data in the .got section.  Note that we
 290       // always create a PLT if we create a GOT, although the PLT
 291       // might be empty.
 292       this->got_plt_ = new Output_data_space(8);
 293       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 294                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 295                                       this->got_plt_);
 296
 297       // The first three entries are reserved.
 298       this->got_plt_->set_space_size(3 * 8);
 299
 300       // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
 301       symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
 302                                     this->got_plt_,
 303                                     0, 0, elfcpp::STT_OBJECT,
 304                                     elfcpp::STB_LOCAL,
 305                                     elfcpp::STV_HIDDEN, 0,
 306                                     false, false);
 307     }
 308
 309   return this->got_;
 310 }
 311
 312 // Get the dynamic reloc section, creating it if necessary.
 313
 314 Target_x86_64::Reloc_section*
 315 Target_x86_64::rela_dyn_section(Layout* layout)
 316 {
 317   if (this->rela_dyn_ == NULL)
 318     {
 319       gold_assert(layout != NULL);
 320       this->rela_dyn_ = new Reloc_section();
 321       layout->add_output_section_data(".rela.dyn", elfcpp::SHT_RELA,
 322                                       elfcpp::SHF_ALLOC, this->rela_dyn_);
 323     }
 324   return this->rela_dyn_;
 325 }
 326
 327 // A class to handle the PLT data.
 328
 329 class Output_data_plt_x86_64 : public Output_section_data
 330 {
 331  public:
 332   typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
 333
 334   Output_data_plt_x86_64(Layout*, Output_data_space*);
 335
 336   // Add an entry to the PLT.
 337   void
 338   add_entry(Symbol* gsym);
 339
 340   // Return the .rel.plt section data.
 341   const Reloc_section*
 342   rel_plt() const
 343   { return this->rel_; }
 344
 345  protected:
 346   void
 347   do_adjust_output_section(Output_section* os);
 348
 349  private:
 350   // The size of an entry in the PLT.
 351   static const int plt_entry_size = 16;
 352
 353   // The first entry in the PLT.
 354   // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same
 355   // procedure linkage table for both programs and shared objects."
 356   static unsigned char first_plt_entry[plt_entry_size];
 357
 358   // Other entries in the PLT for an executable.
 359   static unsigned char plt_entry[plt_entry_size];
 360
 361   // Set the final size.
 362   void
 363   do_set_address(uint64_t, off_t)
 364   { this->set_data_size((this->count_ + 1) * plt_entry_size); }
 365
 366   // Write out the PLT data.
 367   void
 368   do_write(Output_file*);
 369
 370   // The reloc section.
 371   Reloc_section* rel_;
 372   // The .got.plt section.
 373   Output_data_space* got_plt_;
 374   // The number of PLT entries.
 375   unsigned int count_;
 376 };
 377
 378 // Create the PLT section.  The ordinary .got section is an argument,
 379 // since we need to refer to the start.  We also create our own .got
 380 // section just for PLT entries.
 381
 382 Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout,
 383                                                Output_data_space* got_plt)
 384   : Output_section_data(8), got_plt_(got_plt), count_(0)
 385 {
 386   this->rel_ = new Reloc_section();
 387   layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
 388                                   elfcpp::SHF_ALLOC, this->rel_);
 389 }
 390
 391 void
 392 Output_data_plt_x86_64::do_adjust_output_section(Output_section* os)
 393 {
 394   // UnixWare sets the entsize of .plt to 4, and so does the old GNU
 395   // linker, and so do we.
 396   os->set_entsize(4);
 397 }
 398
 399 // Add an entry to the PLT.
 400
 401 void
 402 Output_data_plt_x86_64::add_entry(Symbol* gsym)
 403 {
 404   gold_assert(!gsym->has_plt_offset());
 405
 406   // Note that when setting the PLT offset we skip the initial
 407   // reserved PLT entry.
 408   gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
 409
 410   ++this->count_;
 411
 412   off_t got_offset = this->got_plt_->data_size();
 413
 414   // Every PLT entry needs a GOT entry which points back to the PLT
 415   // entry (this will be changed by the dynamic linker, normally
 416   // lazily when the function is called).
 417   this->got_plt_->set_space_size(got_offset + 8);
 418
 419   // Every PLT entry needs a reloc.
 420   gsym->set_needs_dynsym_entry();
 421   this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_,
 422                          got_offset, 0);
 423
 424   // Note that we don't need to save the symbol.  The contents of the
 425   // PLT are independent of which symbols are used.  The symbols only
 426   // appear in the relocations.
 427 }
 428
 429 // The first entry in the PLT for an executable.
 430
 431 unsigned char Output_data_plt_x86_64::first_plt_entry[plt_entry_size] =
 432 {
 433   // From AMD64 ABI Draft 0.98, page 76
 434   0xff, 0x35,   // pushq contents of memory address
 435   0, 0, 0, 0,   // replaced with address of .got + 4
 436   0xff, 0x25,   // jmp indirect
 437   0, 0, 0, 0,   // replaced with address of .got + 8
 438   0x90, 0x90, 0x90, 0x90   // noop (x4)
 439 };
 440
 441 // Subsequent entries in the PLT for an executable.
 442
 443 unsigned char Output_data_plt_x86_64::plt_entry[plt_entry_size] =
 444 {
 445   // From AMD64 ABI Draft 0.98, page 76
 446   0xff, 0x25,   // jmpq indirect
 447   0, 0, 0, 0,   // replaced with address of symbol in .got
 448   0x68,         // pushq immediate
 449   0, 0, 0, 0,   // replaced with offset into relocation table
 450   0xe9,         // jmpq relative
 451   0, 0, 0, 0    // replaced with offset to start of .plt
 452 };
 453
 454 // Write out the PLT.  This uses the hand-coded instructions above,
 455 // and adjusts them as needed.  This is specified by the AMD64 ABI.
 456
 457 void
 458 Output_data_plt_x86_64::do_write(Output_file* of)
 459 {
 460   const off_t offset = this->offset();
 461   const off_t oview_size = this->data_size();
 462   unsigned char* const oview = of->get_output_view(offset, oview_size);
 463
 464   const off_t got_file_offset = this->got_plt_->offset();
 465   const off_t got_size = this->got_plt_->data_size();
 466   unsigned char* const got_view = of->get_output_view(got_file_offset,
 467                                                       got_size);
 468
 469   unsigned char* pov = oview;
 470
 471   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
 472   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 473
 474   memcpy(pov, first_plt_entry, plt_entry_size);
 475   if (!parameters->output_is_shared())
 476     {
 477       // We do a jmp relative to the PC at the end of this instruction.
 478       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 8
 479                                                   - (plt_address + 6));
 480       elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 16
 481                                         - (plt_address + 12));
 482     }
 483   pov += plt_entry_size;
 484
 485   unsigned char* got_pov = got_view;
 486
 487   memset(got_pov, 0, 24);
 488   got_pov += 24;
 489
 490   unsigned int plt_offset = plt_entry_size;
 491   unsigned int got_offset = 24;
 492   const unsigned int count = this->count_;
 493   for (unsigned int plt_index = 0;
 494        plt_index < count;
 495        ++plt_index,
 496          pov += plt_entry_size,
 497          got_pov += 8,
 498          plt_offset += plt_entry_size,
 499          got_offset += 8)
 500     {
 501       // Set and adjust the PLT entry itself.
 502       memcpy(pov, plt_entry, plt_entry_size);
 503       if (parameters->output_is_shared())
 504         // FIXME(csilvers): what's the right thing to write here?
 505         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
 506       else
 507         elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 508                                                     (got_address + got_offset
 509                                                      - (plt_address + plt_offset
 510                                                         + 6)));
 511
 512       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_index);
 513       elfcpp::Swap<32, false>::writeval(pov + 12,
 514                                         - (plt_offset + plt_entry_size));
 515
 516       // Set the entry in the GOT.
 517       elfcpp::Swap<64, false>::writeval(got_pov, plt_address + plt_offset + 6);
 518     }
 519
 520   gold_assert(pov - oview == oview_size);
 521   gold_assert(got_pov - got_view == got_size);
 522
 523   of->write_output_view(offset, oview_size, oview);
 524   of->write_output_view(got_file_offset, got_size, got_view);
 525 }
 526
 527 // Create a PLT entry for a global symbol.
 528
 529 void
 530 Target_x86_64::make_plt_entry(Symbol_table* symtab, Layout* layout,
 531                               Symbol* gsym)
 532 {
 533   if (gsym->has_plt_offset())
 534     return;
 535
 536   if (this->plt_ == NULL)
 537     {
 538       // Create the GOT sections first.
 539       this->got_section(symtab, layout);
 540
 541       this->plt_ = new Output_data_plt_x86_64(layout, this->got_plt_);
 542       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 543                                       (elfcpp::SHF_ALLOC
 544                                        | elfcpp::SHF_EXECINSTR),
 545                                       this->plt_);
 546     }
 547
 548   this->plt_->add_entry(gsym);
 549 }
 550
 551 // Handle a relocation against a non-function symbol defined in a
 552 // dynamic object.  The traditional way to handle this is to generate
 553 // a COPY relocation to copy the variable at runtime from the shared
 554 // object into the executable's data segment.  However, this is
 555 // undesirable in general, as if the size of the object changes in the
 556 // dynamic object, the executable will no longer work correctly.  If
 557 // this relocation is in a writable section, then we can create a
 558 // dynamic reloc and the dynamic linker will resolve it to the correct
 559 // address at runtime.  However, we do not want do that if the
 560 // relocation is in a read-only section, as it would prevent the
 561 // readonly segment from being shared.  And if we have to eventually
 562 // generate a COPY reloc, then any dynamic relocations will be
 563 // useless.  So this means that if this is a writable section, we need
 564 // to save the relocation until we see whether we have to create a
 565 // COPY relocation for this symbol for any other relocation.
 566
 567 void
 568 Target_x86_64::copy_reloc(const General_options* options,
 569                           Symbol_table* symtab,
 570                           Layout* layout,
 571                           Sized_relobj<64, false>* object,
 572                           unsigned int data_shndx, Symbol* gsym,
 573                           const elfcpp::Rela<64, false>& rela)
 574 {
 575   Sized_symbol<64>* ssym;
 576   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(64) (gsym
 577                                                         SELECT_SIZE(64));
 578
 579   if (!Copy_relocs<64, false>::need_copy_reloc(options, object,
 580                                                data_shndx, ssym))
 581     {
 582       // So far we do not need a COPY reloc.  Save this relocation.
 583       // If it turns out that we never need a COPY reloc for this
 584       // symbol, then we will emit the relocation.
 585       if (this->copy_relocs_ == NULL)
 586         this->copy_relocs_ = new Copy_relocs<64, false>();
 587       this->copy_relocs_->save(ssym, object, data_shndx, rela);
 588     }
 589   else
 590     {
 591       // Allocate space for this symbol in the .bss section.
 592
 593       elfcpp::Elf_types<64>::Elf_WXword symsize = ssym->symsize();
 594
 595       // There is no defined way to determine the required alignment
 596       // of the symbol.  We pick the alignment based on the size.  We
 597       // set an arbitrary maximum of 256.
 598       unsigned int align;
 599       for (align = 1; align < 512; align <<= 1)
 600         if ((symsize & align) != 0)
 601           break;
 602
 603       if (this->dynbss_ == NULL)
 604         {
 605           this->dynbss_ = new Output_data_space(align);
 606           layout->add_output_section_data(".bss",
 607                                           elfcpp::SHT_NOBITS,
 608                                           (elfcpp::SHF_ALLOC
 609                                            | elfcpp::SHF_WRITE),
 610                                           this->dynbss_);
 611         }
 612
 613       Output_data_space* dynbss = this->dynbss_;
 614
 615       if (align > dynbss->addralign())
 616         dynbss->set_space_alignment(align);
 617
 618       off_t dynbss_size = dynbss->data_size();
 619       dynbss_size = align_address(dynbss_size, align);
 620       off_t offset = dynbss_size;
 621       dynbss->set_space_size(dynbss_size + symsize);
 622
 623       symtab->define_with_copy_reloc(this, ssym, dynbss, offset);
 624
 625       // Add the COPY reloc.
 626       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
 627       rela_dyn->add_global(ssym, elfcpp::R_X86_64_COPY, dynbss, offset, 0);
 628     }
 629 }
 630
 631
 632 // Optimize the TLS relocation type based on what we know about the
 633 // symbol.  IS_FINAL is true if the final address of this symbol is
 634 // known at link time.
 635
 636 tls::Tls_optimization
 637 Target_x86_64::optimize_tls_reloc(bool is_final, int r_type)
 638 {
 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 tls::TLSOPT_NONE;
 643
 644   switch (r_type)
 645     {
 646     case elfcpp::R_X86_64_TLSGD:
 647     case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 648     case elfcpp::R_X86_64_TLSDESC_CALL:
 649       // These are General-Dynamic which permits fully general TLS
 650       // access.  Since we know that we are generating an executable,
 651       // we can convert this to Initial-Exec.  If we also know that
 652       // this is a local symbol, we can further switch to Local-Exec.
 653       if (is_final)
 654         return tls::TLSOPT_TO_LE;
 655       return tls::TLSOPT_TO_IE;
 656
 657     case elfcpp::R_X86_64_TLSLD:
 658       // This is Local-Dynamic, which refers to a local symbol in the
 659       // dynamic TLS block.  Since we know that we generating an
 660       // executable, we can switch to Local-Exec.
 661       return tls::TLSOPT_TO_LE;
 662
 663     case elfcpp::R_X86_64_DTPOFF32:
 664     case elfcpp::R_X86_64_DTPOFF64:
 665       // Another Local-Dynamic reloc.
 666       return tls::TLSOPT_TO_LE;
 667
 668     case elfcpp::R_X86_64_GOTTPOFF:
 669       // These are Initial-Exec relocs which get the thread offset
 670       // from the GOT.  If we know that we are linking against the
 671       // local symbol, we can switch to Local-Exec, which links the
 672       // thread offset into the instruction.
 673       if (is_final)
 674         return tls::TLSOPT_TO_LE;
 675       return tls::TLSOPT_NONE;
 676
 677     case elfcpp::R_X86_64_TPOFF32:
 678       // When we already have Local-Exec, there is nothing further we
 679       // can do.
 680       return tls::TLSOPT_NONE;
 681
 682     default:
 683       gold_unreachable();
 684     }
 685 }
 686
 687 // Report an unsupported relocation against a local symbol.
 688
 689 void
 690 Target_x86_64::Scan::unsupported_reloc_local(Sized_relobj<64, false>* object,
 691                                              unsigned int r_type)
 692 {
 693   gold_error(_("%s: unsupported reloc %u against local symbol"),
 694              object->name().c_str(), r_type);
 695 }
 696
 697 // Scan a relocation for a local symbol.
 698
 699 inline void
 700 Target_x86_64::Scan::local(const General_options&,
 701                            Symbol_table* symtab,
 702                            Layout* layout,
 703                            Target_x86_64* target,
 704                            Sized_relobj<64, false>* object,
 705                            unsigned int data_shndx,
 706                            const elfcpp::Rela<64, false>& reloc,
 707                            unsigned int r_type,
 708                            const elfcpp::Sym<64, false>&)
 709 {
 710   switch (r_type)
 711     {
 712     case elfcpp::R_X86_64_NONE:
 713     case elfcpp::R_386_GNU_VTINHERIT:
 714     case elfcpp::R_386_GNU_VTENTRY:
 715       break;
 716
 717     case elfcpp::R_X86_64_64:
 718     case elfcpp::R_X86_64_32:
 719     case elfcpp::R_X86_64_32S:
 720     case elfcpp::R_X86_64_16:
 721     case elfcpp::R_X86_64_8:
 722       // FIXME: If we are generating a shared object we need to copy
 723       // this relocation into the object.
 724       gold_assert(!parameters->output_is_shared());
 725       break;
 726
 727     case elfcpp::R_X86_64_PC64:
 728     case elfcpp::R_X86_64_PC32:
 729     case elfcpp::R_X86_64_PC16:
 730     case elfcpp::R_X86_64_PC8:
 731       break;
 732
 733     case elfcpp::R_X86_64_PLT32:
 734       // Since we know this is a local symbol, we can handle this as a
 735       // PC32 reloc.
 736       break;
 737
 738     case elfcpp::R_X86_64_GOTPC32:
 739     case elfcpp::R_X86_64_GOTOFF64:
 740     case elfcpp::R_X86_64_GOTPC64:
 741     case elfcpp::R_X86_64_PLTOFF64:
 742       // We need a GOT section.
 743       target->got_section(symtab, layout);
 744       // For PLTOFF64, we'd normally want a PLT section, but since we
 745       // know this is a local symbol, no PLT is needed.
 746       break;
 747
 748     case elfcpp::R_X86_64_GOT64:
 749     case elfcpp::R_X86_64_GOT32:
 750     case elfcpp::R_X86_64_GOTPCREL64:
 751     case elfcpp::R_X86_64_GOTPCREL:
 752     case elfcpp::R_X86_64_GOTPLT64:
 753       {
 754         // The symbol requires a GOT entry.
 755         Output_data_got<64, false>* got = target->got_section(symtab, layout);
 756         unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
 757         if (got->add_local(object, r_sym))
 758           {
 759             // If we are generating a shared object, we need to add a
 760             // dynamic RELATIVE relocation for this symbol.
 761             if (parameters->output_is_shared())
 762               {
 763                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 764                 rela_dyn->add_local(object, 0, elfcpp::R_X86_64_RELATIVE,
 765                                     data_shndx, reloc.get_r_offset(), 0);
 766               }
 767           }
 768         // For GOTPLT64, we'd normally want a PLT section, but since
 769         // we know this is a local symbol, no PLT is needed.
 770       }
 771       break;
 772
 773     case elfcpp::R_X86_64_COPY:
 774     case elfcpp::R_X86_64_GLOB_DAT:
 775     case elfcpp::R_X86_64_JUMP_SLOT:
 776     case elfcpp::R_X86_64_RELATIVE:
 777       // These are outstanding tls relocs, which are unexpected when linking
 778     case elfcpp::R_X86_64_TPOFF64:
 779     case elfcpp::R_X86_64_DTPMOD64:
 780     case elfcpp::R_X86_64_TLSDESC:
 781       gold_error(_("%s: unexpected reloc %u in object file"),
 782                  object->name().c_str(), r_type);
 783       break;
 784
 785       // These are initial tls relocs, which are expected when linking
 786     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
 787     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
 788     case elfcpp::R_X86_64_TLSDESC_CALL:
 789     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
 790     case elfcpp::R_X86_64_DTPOFF32:
 791     case elfcpp::R_X86_64_DTPOFF64:
 792     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
 793     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
 794       {
 795         bool output_is_shared = parameters->output_is_shared();
 796         const tls::Tls_optimization optimized_type
 797             = Target_x86_64::optimize_tls_reloc(!output_is_shared, r_type);
 798         switch (r_type)
 799           {
 800           case elfcpp::R_X86_64_TLSGD:       // General-dynamic
 801           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 802           case elfcpp::R_X86_64_TLSDESC_CALL:
 803             // FIXME: If not relaxing to LE, we need to generate
 804             // DTPMOD64 and DTPOFF64 relocs.
 805             if (optimized_type != tls::TLSOPT_TO_LE)
 806               unsupported_reloc_local(object, r_type);
 807             break;
 808
 809           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
 810           case elfcpp::R_X86_64_DTPOFF32:
 811           case elfcpp::R_X86_64_DTPOFF64:
 812             // FIXME: If not relaxing to LE, we need to generate a
 813             // DTPMOD64 reloc.
 814             if (optimized_type != tls::TLSOPT_TO_LE)
 815               unsupported_reloc_local(object, r_type);
 816             break;
 817
 818           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
 819             // FIXME: If not relaxing to LE, we need to generate a
 820             // TPOFF64 reloc.
 821             if (optimized_type != tls::TLSOPT_TO_LE)
 822               unsupported_reloc_local(object, r_type);
 823             break;
 824
 825           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
 826             // FIXME: If generating a shared object, we need to copy
 827             // this relocation into the object.
 828             gold_assert(!output_is_shared);
 829             break;
 830
 831           default:
 832             gold_unreachable();
 833           }
 834       }
 835       break;
 836
 837     case elfcpp::R_X86_64_SIZE32:
 838     case elfcpp::R_X86_64_SIZE64:
 839     default:
 840       gold_error(_("%s: unsupported reloc %u against local symbol"),
 841                  object->name().c_str(), r_type);
 842       break;
 843     }
 844 }
 845
 846
 847 // Report an unsupported relocation against a global symbol.
 848
 849 void
 850 Target_x86_64::Scan::unsupported_reloc_global(Sized_relobj<64, false>* object,
 851                                               unsigned int r_type,
 852                                               Symbol* gsym)
 853 {
 854   gold_error(_("%s: unsupported reloc %u against global symbol %s"),
 855              object->name().c_str(), r_type, gsym->name());
 856 }
 857
 858 // Scan a relocation for a global symbol.
 859
 860 inline void
 861 Target_x86_64::Scan::global(const General_options& options,
 862                             Symbol_table* symtab,
 863                             Layout* layout,
 864                             Target_x86_64* target,
 865                             Sized_relobj<64, false>* object,
 866                             unsigned int data_shndx,
 867                             const elfcpp::Rela<64, false>& reloc,
 868                             unsigned int r_type,
 869                             Symbol* gsym)
 870 {
 871   switch (r_type)
 872     {
 873     case elfcpp::R_X86_64_NONE:
 874     case elfcpp::R_386_GNU_VTINHERIT:
 875     case elfcpp::R_386_GNU_VTENTRY:
 876       break;
 877
 878     case elfcpp::R_X86_64_64:
 879     case elfcpp::R_X86_64_PC64:
 880     case elfcpp::R_X86_64_32:
 881     case elfcpp::R_X86_64_32S:
 882     case elfcpp::R_X86_64_PC32:
 883     case elfcpp::R_X86_64_16:
 884     case elfcpp::R_X86_64_PC16:
 885     case elfcpp::R_X86_64_8:
 886     case elfcpp::R_X86_64_PC8:
 887       // FIXME: If we are generating a shared object we may need to
 888       // copy this relocation into the object.  If this symbol is
 889       // defined in a shared object, we may need to copy this
 890       // relocation in order to avoid a COPY relocation.
 891       gold_assert(!parameters->output_is_shared());
 892
 893       if (gsym->is_from_dynobj())
 894         {
 895           // This symbol is defined in a dynamic object.  If it is a
 896           // function, we make a PLT entry.  Otherwise we need to
 897           // either generate a COPY reloc or copy this reloc.
 898           if (gsym->type() == elfcpp::STT_FUNC)
 899             {
 900               target->make_plt_entry(symtab, layout, gsym);
 901
 902               // If this is not a PC relative reference, then we may
 903               // be taking the address of the function.  In that case
 904               // we need to set the entry in the dynamic symbol table
 905               // to the address of the PLT entry.
 906               if (r_type != elfcpp::R_X86_64_PC64
 907                   && r_type != elfcpp::R_X86_64_PC32
 908                   && r_type != elfcpp::R_X86_64_PC16
 909                   && r_type != elfcpp::R_X86_64_PC8)
 910                 gsym->set_needs_dynsym_value();
 911             }
 912           else
 913             target->copy_reloc(&options, symtab, layout, object, data_shndx,
 914                                gsym, reloc);
 915         }
 916
 917       break;
 918
 919     case elfcpp::R_X86_64_GOT64:
 920     case elfcpp::R_X86_64_GOT32:
 921     case elfcpp::R_X86_64_GOTPCREL64:
 922     case elfcpp::R_X86_64_GOTPCREL:
 923     case elfcpp::R_X86_64_GOTPLT64:
 924       {
 925         // The symbol requires a GOT entry.
 926         Output_data_got<64, false>* got = target->got_section(symtab, layout);
 927         if (got->add_global(gsym))
 928           {
 929             // If this symbol is not fully resolved, we need to add a
 930             // dynamic relocation for it.
 931             if (!gsym->final_value_is_known())
 932               {
 933                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
 934                 rela_dyn->add_global(gsym, elfcpp::R_X86_64_GLOB_DAT, got,
 935                                      gsym->got_offset(), 0);
 936               }
 937           }
 938         // For GOTPLT64, we also need a PLT entry (but only if the
 939         // symbol is not fully resolved).
 940         if (r_type == elfcpp::R_X86_64_GOTPLT64
 941             && !gsym->final_value_is_known())
 942           target->make_plt_entry(symtab, layout, gsym);
 943       }
 944       break;
 945
 946     case elfcpp::R_X86_64_PLT32:
 947       // If the symbol is fully resolved, this is just a PC32 reloc.
 948       // Otherwise we need a PLT entry.
 949       if (gsym->final_value_is_known())
 950         break;
 951       target->make_plt_entry(symtab, layout, gsym);
 952       break;
 953
 954     case elfcpp::R_X86_64_GOTPC32:
 955     case elfcpp::R_X86_64_GOTOFF64:
 956     case elfcpp::R_X86_64_GOTPC64:
 957     case elfcpp::R_X86_64_PLTOFF64:
 958       // We need a GOT section.
 959       target->got_section(symtab, layout);
 960       // For PLTOFF64, we also need a PLT entry (but only if the
 961       // symbol is not fully resolved).
 962       if (r_type == elfcpp::R_X86_64_PLTOFF64
 963           && !gsym->final_value_is_known())
 964         target->make_plt_entry(symtab, layout, gsym);
 965       break;
 966
 967     case elfcpp::R_X86_64_COPY:
 968     case elfcpp::R_X86_64_GLOB_DAT:
 969     case elfcpp::R_X86_64_JUMP_SLOT:
 970     case elfcpp::R_X86_64_RELATIVE:
 971       // These are outstanding tls relocs, which are unexpected when linking
 972     case elfcpp::R_X86_64_TPOFF64:
 973     case elfcpp::R_X86_64_DTPMOD64:
 974     case elfcpp::R_X86_64_TLSDESC:
 975       gold_error(_("%s: unexpected reloc %u in object file"),
 976                  object->name().c_str(), r_type);
 977       break;
 978
 979       // These are initial tls relocs, which are expected for global()
 980     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
 981     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
 982     case elfcpp::R_X86_64_TLSDESC_CALL:
 983     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
 984     case elfcpp::R_X86_64_DTPOFF32:
 985     case elfcpp::R_X86_64_DTPOFF64:
 986     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
 987     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
 988       {
 989         const bool is_final = gsym->final_value_is_known();
 990         const tls::Tls_optimization optimized_type
 991             = Target_x86_64::optimize_tls_reloc(is_final, r_type);
 992         switch (r_type)
 993           {
 994           case elfcpp::R_X86_64_TLSGD:       // General-dynamic
 995           case elfcpp::R_X86_64_GOTPC32_TLSDESC:
 996           case elfcpp::R_X86_64_TLSDESC_CALL:
 997             // FIXME: If not relaxing to LE, we need to generate
 998             // DTPMOD64 and DTPOFF64, or TLSDESC, relocs.
 999             if (optimized_type != tls::TLSOPT_TO_LE)
1000               unsupported_reloc_global(object, r_type, gsym);
1001             break;
1002
1003           case elfcpp::R_X86_64_TLSLD:       // Local-dynamic
1004           case elfcpp::R_X86_64_DTPOFF32:
1005           case elfcpp::R_X86_64_DTPOFF64:
1006             // FIXME: If not relaxing to LE, we need to generate a
1007             // DTPMOD64 reloc.
1008             if (optimized_type != tls::TLSOPT_TO_LE)
1009               unsupported_reloc_global(object, r_type, gsym);
1010             break;
1011
1012           case elfcpp::R_X86_64_GOTTPOFF:    // Initial-exec
1013             // FIXME: If not relaxing to LE, we need to generate a
1014             // TPOFF64 reloc.
1015             if (optimized_type != tls::TLSOPT_TO_LE)
1016               unsupported_reloc_global(object, r_type, gsym);
1017             break;
1018
1019           case elfcpp::R_X86_64_TPOFF32:     // Local-exec
1020             // FIXME: If generating a shared object, we need to copy
1021             // this relocation into the object.
1022             gold_assert(is_final);
1023             break;
1024
1025           default:
1026             gold_unreachable();
1027           }
1028       }
1029       break;
1030
1031     case elfcpp::R_X86_64_SIZE32:
1032     case elfcpp::R_X86_64_SIZE64:
1033     default:
1034       gold_error(_("%s: unsupported reloc %u against global symbol %s"),
1035                  object->name().c_str(), r_type, gsym->name());
1036       break;
1037     }
1038 }
1039
1040 // Scan relocations for a section.
1041
1042 void
1043 Target_x86_64::scan_relocs(const General_options& options,
1044                            Symbol_table* symtab,
1045                            Layout* layout,
1046                            Sized_relobj<64, false>* object,
1047                            unsigned int data_shndx,
1048                            unsigned int sh_type,
1049                            const unsigned char* prelocs,
1050                            size_t reloc_count,
1051                            size_t local_symbol_count,
1052                            const unsigned char* plocal_symbols,
1053                            Symbol** global_symbols)
1054 {
1055   if (sh_type == elfcpp::SHT_REL)
1056     {
1057       gold_error(_("%s: unsupported REL reloc section"),
1058                  object->name().c_str());
1059       return;
1060     }
1061
1062   gold::scan_relocs<64, false, Target_x86_64, elfcpp::SHT_RELA,
1063       Target_x86_64::Scan>(
1064     options,
1065     symtab,
1066     layout,
1067     this,
1068     object,
1069     data_shndx,
1070     prelocs,
1071     reloc_count,
1072     local_symbol_count,
1073     plocal_symbols,
1074     global_symbols);
1075 }
1076
1077 // Finalize the sections.
1078
1079 void
1080 Target_x86_64::do_finalize_sections(Layout* layout)
1081 {
1082   // Fill in some more dynamic tags.
1083   Output_data_dynamic* const odyn = layout->dynamic_data();
1084   if (odyn != NULL)
1085     {
1086       if (this->got_plt_ != NULL)
1087         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1088
1089       if (this->plt_ != NULL)
1090         {
1091           const Output_data* od = this->plt_->rel_plt();
1092           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1093           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1094           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_RELA);
1095         }
1096
1097       if (this->rela_dyn_ != NULL)
1098         {
1099           const Output_data* od = this->rela_dyn_;
1100           odyn->add_section_address(elfcpp::DT_RELA, od);
1101           odyn->add_section_size(elfcpp::DT_RELASZ, od);
1102           odyn->add_constant(elfcpp::DT_RELAENT,
1103                              elfcpp::Elf_sizes<64>::rela_size);
1104         }
1105
1106       if (!parameters->output_is_shared())
1107         {
1108           // The value of the DT_DEBUG tag is filled in by the dynamic
1109           // linker at run time, and used by the debugger.
1110           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1111         }
1112     }
1113
1114   // Emit any relocs we saved in an attempt to avoid generating COPY
1115   // relocs.
1116   if (this->copy_relocs_ == NULL)
1117     return;
1118   if (this->copy_relocs_->any_to_emit())
1119     {
1120       Reloc_section* rela_dyn = this->rela_dyn_section(layout);
1121       this->copy_relocs_->emit(rela_dyn);
1122     }
1123   delete this->copy_relocs_;
1124   this->copy_relocs_ = NULL;
1125 }
1126
1127 // Perform a relocation.
1128
1129 inline bool
1130 Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo,
1131                                   Target_x86_64* target,
1132                                   size_t relnum,
1133                                   const elfcpp::Rela<64, false>& rela,
1134                                   unsigned int r_type,
1135                                   const Sized_symbol<64>* gsym,
1136                                   const Symbol_value<64>* psymval,
1137                                   unsigned char* view,
1138                                   elfcpp::Elf_types<64>::Elf_Addr address,
1139                                   off_t view_size)
1140 {
1141   if (this->skip_call_tls_get_addr_)
1142     {
1143       if (r_type != elfcpp::R_X86_64_PLT32
1144           || gsym == NULL
1145           || strcmp(gsym->name(), "__tls_get_addr") != 0)
1146         {
1147           gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1148                                  _("missing expected TLS relocation"));
1149         }
1150       else
1151         {
1152           this->skip_call_tls_get_addr_ = false;
1153           return false;
1154         }
1155     }
1156
1157   // Pick the value to use for symbols defined in shared objects.
1158   Symbol_value<64> symval;
1159   if (gsym != NULL && gsym->is_from_dynobj() && gsym->has_plt_offset())
1160     {
1161       symval.set_output_value(target->plt_section()->address()
1162                               + gsym->plt_offset());
1163       psymval = &symval;
1164     }
1165
1166   const Sized_relobj<64, false>* object = relinfo->object;
1167   const elfcpp::Elf_Xword addend = rela.get_r_addend();
1168
1169   // Get the GOT offset if needed.
1170   bool have_got_offset = false;
1171   unsigned int got_offset = 0;
1172   switch (r_type)
1173     {
1174     case elfcpp::R_X86_64_GOT32:
1175     case elfcpp::R_X86_64_GOT64:
1176     case elfcpp::R_X86_64_GOTPLT64:
1177     case elfcpp::R_X86_64_GOTPCREL:
1178     case elfcpp::R_X86_64_GOTPCREL64:
1179       if (gsym != NULL)
1180         {
1181           gold_assert(gsym->has_got_offset());
1182           got_offset = gsym->got_offset();
1183         }
1184       else
1185         {
1186           unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
1187           got_offset = object->local_got_offset(r_sym);
1188         }
1189       have_got_offset = true;
1190       break;
1191
1192     default:
1193       break;
1194     }
1195
1196   switch (r_type)
1197     {
1198     case elfcpp::R_X86_64_NONE:
1199     case elfcpp::R_386_GNU_VTINHERIT:
1200     case elfcpp::R_386_GNU_VTENTRY:
1201       break;
1202
1203     case elfcpp::R_X86_64_64:
1204       Relocate_functions<64, false>::rela64(view, object, psymval, addend);
1205       break;
1206
1207     case elfcpp::R_X86_64_PC64:
1208       Relocate_functions<64, false>::pcrela64(view, object, psymval, addend,
1209                                               address);
1210       break;
1211
1212     case elfcpp::R_X86_64_32:
1213       // FIXME: we need to verify that value + addend fits into 32 bits:
1214       //    uint64_t x = value + addend;
1215       //    x == static_cast<uint64_t>(static_cast<uint32_t>(x))
1216       // Likewise for other <=32-bit relocations (but see R_X86_64_32S).
1217       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1218       break;
1219
1220     case elfcpp::R_X86_64_32S:
1221       // FIXME: we need to verify that value + addend fits into 32 bits:
1222       //    int64_t x = value + addend;   // note this quantity is signed!
1223       //    x == static_cast<int64_t>(static_cast<int32_t>(x))
1224       Relocate_functions<64, false>::rela32(view, object, psymval, addend);
1225       break;
1226
1227     case elfcpp::R_X86_64_PC32:
1228       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1229                                               address);
1230       break;
1231
1232     case elfcpp::R_X86_64_16:
1233       Relocate_functions<64, false>::rela16(view, object, psymval, addend);
1234       break;
1235
1236     case elfcpp::R_X86_64_PC16:
1237       Relocate_functions<64, false>::pcrela16(view, object, psymval, addend,
1238                                               address);
1239       break;
1240
1241     case elfcpp::R_X86_64_8:
1242       Relocate_functions<64, false>::rela8(view, object, psymval, addend);
1243       break;
1244
1245     case elfcpp::R_X86_64_PC8:
1246       Relocate_functions<64, false>::pcrela8(view, object, psymval, addend,
1247                                              address);
1248       break;
1249
1250     case elfcpp::R_X86_64_PLT32:
1251       gold_assert(gsym == NULL
1252                   || gsym->has_plt_offset()
1253                   || gsym->final_value_is_known());
1254       // Note: while this code looks the same as for R_X86_64_PC32, it
1255       // behaves differently because psymval was set to point to
1256       // the PLT entry, rather than the symbol, in Scan::global().
1257       Relocate_functions<64, false>::pcrela32(view, object, psymval, addend,
1258                                               address);
1259       break;
1260
1261     case elfcpp::R_X86_64_PLTOFF64:
1262       {
1263         gold_assert(gsym);
1264         gold_assert(gsym->has_plt_offset()
1265                     || gsym->final_value_is_known());
1266         elfcpp::Elf_types<64>::Elf_Addr got_address;
1267         got_address = target->got_section(NULL, NULL)->address();
1268         Relocate_functions<64, false>::pcrela64(view, object, psymval, addend,
1269                                                 - got_address);
1270       }
1271
1272     case elfcpp::R_X86_64_GOT32:
1273       gold_assert(have_got_offset);
1274       Relocate_functions<64, false>::rela32(view, got_offset, addend);
1275       break;
1276
1277     case elfcpp::R_X86_64_GOTPC32:
1278       {
1279         gold_assert(gsym);
1280         elfcpp::Elf_types<64>::Elf_Addr value;
1281         value = target->got_section(NULL, NULL)->address();
1282         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1283       }
1284       break;
1285
1286     case elfcpp::R_X86_64_GOT64:
1287       // The ABI doc says "Like GOT64, but indicates a PLT entry is needed."
1288       // Since we always add a PLT entry, this is equivalent.
1289     case elfcpp::R_X86_64_GOTPLT64:
1290       gold_assert(have_got_offset);
1291       Relocate_functions<64, false>::rela64(view, got_offset, addend);
1292       break;
1293
1294     case elfcpp::R_X86_64_GOTPC64:
1295       {
1296         gold_assert(gsym);
1297         elfcpp::Elf_types<64>::Elf_Addr value;
1298         value = target->got_section(NULL, NULL)->address();
1299         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1300       }
1301       break;
1302
1303     case elfcpp::R_X86_64_GOTOFF64:
1304       {
1305         elfcpp::Elf_types<64>::Elf_Addr value;
1306         value = (psymval->value(object, 0)
1307                  - target->got_section(NULL, NULL)->address());
1308         Relocate_functions<64, false>::rela64(view, value, addend);
1309       }
1310       break;
1311
1312     case elfcpp::R_X86_64_GOTPCREL:
1313       {
1314         gold_assert(have_got_offset);
1315         elfcpp::Elf_types<64>::Elf_Addr value;
1316         value = target->got_section(NULL, NULL)->address() + got_offset;
1317         Relocate_functions<64, false>::pcrela32(view, value, addend, address);
1318       }
1319       break;
1320
1321     case elfcpp::R_X86_64_GOTPCREL64:
1322       {
1323         gold_assert(have_got_offset);
1324         elfcpp::Elf_types<64>::Elf_Addr value;
1325         value = target->got_section(NULL, NULL)->address() + got_offset;
1326         Relocate_functions<64, false>::pcrela64(view, value, addend, address);
1327       }
1328       break;
1329
1330     case elfcpp::R_X86_64_COPY:
1331     case elfcpp::R_X86_64_GLOB_DAT:
1332     case elfcpp::R_X86_64_JUMP_SLOT:
1333     case elfcpp::R_X86_64_RELATIVE:
1334       // These are outstanding tls relocs, which are unexpected when linking
1335     case elfcpp::R_X86_64_TPOFF64:
1336     case elfcpp::R_X86_64_DTPMOD64:
1337     case elfcpp::R_X86_64_TLSDESC:
1338       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1339                              _("unexpected reloc %u in object file"),
1340                              r_type);
1341       break;
1342
1343       // These are initial tls relocs, which are expected when linking
1344     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1345     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1346     case elfcpp::R_X86_64_TLSDESC_CALL:
1347     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1348     case elfcpp::R_X86_64_DTPOFF32:
1349     case elfcpp::R_X86_64_DTPOFF64:
1350     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1351     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1352       this->relocate_tls(relinfo, relnum, rela, r_type, gsym, psymval, view,
1353                          address, view_size);
1354       break;
1355
1356     case elfcpp::R_X86_64_SIZE32:
1357     case elfcpp::R_X86_64_SIZE64:
1358     default:
1359       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1360                              _("unsupported reloc %u"),
1361                              r_type);
1362       break;
1363     }
1364
1365   return true;
1366 }
1367
1368 // Perform a TLS relocation.
1369
1370 inline void
1371 Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo,
1372                                       size_t relnum,
1373                                       const elfcpp::Rela<64, false>& rela,
1374                                       unsigned int r_type,
1375                                       const Sized_symbol<64>* gsym,
1376                                       const Symbol_value<64>* psymval,
1377                                       unsigned char* view,
1378                                       elfcpp::Elf_types<64>::Elf_Addr,
1379                                       off_t view_size)
1380 {
1381   Output_segment* tls_segment = relinfo->layout->tls_segment();
1382   if (tls_segment == NULL)
1383     {
1384       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1385                              _("TLS reloc but no TLS segment"));
1386       return;
1387     }
1388
1389   elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0);
1390
1391   const bool is_final = (gsym == NULL
1392                          ? !parameters->output_is_shared()
1393                          : gsym->final_value_is_known());
1394   const tls::Tls_optimization optimized_type
1395       = Target_x86_64::optimize_tls_reloc(is_final, r_type);
1396   switch (r_type)
1397     {
1398     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
1399     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
1400     case elfcpp::R_X86_64_TLSDESC_CALL:
1401       if (optimized_type == tls::TLSOPT_TO_LE)
1402         {
1403           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1404                              rela, r_type, value, view,
1405                              view_size);
1406           break;
1407         }
1408       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1409                              _("unsupported reloc %u"), r_type);
1410       break;
1411
1412     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
1413       if (optimized_type == tls::TLSOPT_TO_LE)
1414         {
1415           this->tls_ld_to_le(relinfo, relnum, tls_segment, rela, r_type,
1416                              value, view, view_size);
1417           break;
1418         }
1419       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1420                              _("unsupported reloc %u"), r_type);
1421       break;
1422
1423     case elfcpp::R_X86_64_DTPOFF32:
1424       if (optimized_type == tls::TLSOPT_TO_LE)
1425         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1426       else
1427         value = value - tls_segment->vaddr();
1428       Relocate_functions<64, false>::rel32(view, value);
1429       break;
1430
1431     case elfcpp::R_X86_64_DTPOFF64:
1432       if (optimized_type == tls::TLSOPT_TO_LE)
1433         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1434       else
1435         value = value - tls_segment->vaddr();
1436       Relocate_functions<64, false>::rel64(view, value);
1437       break;
1438
1439     case elfcpp::R_X86_64_GOTTPOFF:         // Initial-exec
1440       if (optimized_type == tls::TLSOPT_TO_LE)
1441         {
1442           Target_x86_64::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1443                                                 rela, r_type, value, view,
1444                                                 view_size);
1445           break;
1446         }
1447       gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
1448                              _("unsupported reloc type %u"),
1449                              r_type);
1450       break;
1451
1452     case elfcpp::R_X86_64_TPOFF32:          // Local-exec
1453       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1454       Relocate_functions<64, false>::rel32(view, value);
1455       break;
1456     }
1457 }
1458
1459 // Do a relocation in which we convert a TLS General-Dynamic to a
1460 // Local-Exec.
1461
1462 inline void
1463 Target_x86_64::Relocate::tls_gd_to_le(const Relocate_info<64, false>* relinfo,
1464                                       size_t relnum,
1465                                       Output_segment* tls_segment,
1466                                       const elfcpp::Rela<64, false>& rela,
1467                                       unsigned int,
1468                                       elfcpp::Elf_types<64>::Elf_Addr value,
1469                                       unsigned char* view,
1470                                       off_t view_size)
1471 {
1472   // .byte 0x66; leaq foo@tlsgd(%rip),%rdi;
1473   // .word 0x6666; rex64; call __tls_get_addr
1474   // ==> movq %fs:0,%rax; leaq x@tpoff(%rax),%rax
1475
1476   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -4);
1477   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12);
1478
1479   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1480                  (memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0));
1481   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1482                  (memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0));
1483
1484   memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x8d\x80\0\0\0\0", 16);
1485
1486   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1487   Relocate_functions<64, false>::rela32(view + 8, value, 0);
1488
1489   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1490   // We can skip it.
1491   this->skip_call_tls_get_addr_ = true;
1492 }
1493
1494 inline void
1495 Target_x86_64::Relocate::tls_ld_to_le(const Relocate_info<64, false>* relinfo,
1496                                       size_t relnum,
1497                                       Output_segment*,
1498                                       const elfcpp::Rela<64, false>& rela,
1499                                       unsigned int,
1500                                       elfcpp::Elf_types<64>::Elf_Addr,
1501                                       unsigned char* view,
1502                                       off_t view_size)
1503 {
1504   // leaq foo@tlsld(%rip),%rdi; call __tls_get_addr@plt;
1505   // ... leq foo@dtpoff(%rax),%reg
1506   // ==> .word 0x6666; .byte 0x66; movq %fs:0,%rax ... leaq x@tpoff(%rax),%rdx
1507
1508   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1509   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 9);
1510
1511   tls::check_tls(relinfo, relnum, rela.get_r_offset(),
1512                  view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x3d);
1513
1514   tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[4] == 0xe8);
1515
1516   memcpy(view - 3, "\x66\x66\x66\x64\x48\x8b\x04\x25\0\0\0\0", 12);
1517
1518   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1519   // We can skip it.
1520   this->skip_call_tls_get_addr_ = true;
1521 }
1522
1523 // Do a relocation in which we convert a TLS Initial-Exec to a
1524 // Local-Exec.
1525
1526 inline void
1527 Target_x86_64::Relocate::tls_ie_to_le(const Relocate_info<64, false>* relinfo,
1528                                       size_t relnum,
1529                                       Output_segment* tls_segment,
1530                                       const elfcpp::Rela<64, false>& rela,
1531                                       unsigned int,
1532                                       elfcpp::Elf_types<64>::Elf_Addr value,
1533                                       unsigned char* view,
1534                                       off_t view_size)
1535 {
1536   // We need to examine the opcodes to figure out which instruction we
1537   // are looking at.
1538
1539   // movq foo@gottpoff(%rip),%reg  ==>  movq $YY,%reg
1540   // addq foo@gottpoff(%rip),%reg  ==>  addq $YY,%reg
1541
1542   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
1543   tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 4);
1544
1545   unsigned char op1 = view[-3];
1546   unsigned char op2 = view[-2];
1547   unsigned char op3 = view[-1];
1548   unsigned char reg = op3 >> 3;
1549
1550   if (op2 == 0x8b)
1551     {
1552       // movq
1553       if (op1 == 0x4c)
1554         view[-3] = 0x49;
1555       view[-2] = 0xc7;
1556       view[-1] = 0xc0 | reg;
1557     }
1558   else if (reg == 4)
1559     {
1560       // Special handling for %rsp.
1561       if (op1 == 0x4c)
1562         view[-3] = 0x49;
1563       view[-2] = 0x81;
1564       view[-1] = 0xc0 | reg;
1565     }
1566   else
1567     {
1568       // addq
1569       if (op1 == 0x4c)
1570         view[-3] = 0x4d;
1571       view[-2] = 0x8d;
1572       view[-1] = 0x80 | reg | (reg << 3);
1573     }
1574
1575   value = value - (tls_segment->vaddr() + tls_segment->memsz());
1576   Relocate_functions<64, false>::rela32(view, value, 0);
1577 }
1578
1579 // Relocate section data.
1580
1581 void
1582 Target_x86_64::relocate_section(const Relocate_info<64, false>* relinfo,
1583                                 unsigned int sh_type,
1584                                 const unsigned char* prelocs,
1585                                 size_t reloc_count,
1586                                 unsigned char* view,
1587                                 elfcpp::Elf_types<64>::Elf_Addr address,
1588                                 off_t view_size)
1589 {
1590   gold_assert(sh_type == elfcpp::SHT_RELA);
1591
1592   gold::relocate_section<64, false, Target_x86_64, elfcpp::SHT_RELA,
1593                          Target_x86_64::Relocate>(
1594     relinfo,
1595     this,
1596     prelocs,
1597     reloc_count,
1598     view,
1599     address,
1600     view_size);
1601 }
1602
1603 // Return the value to use for a dynamic which requires special
1604 // treatment.  This is how we support equality comparisons of function
1605 // pointers across shared library boundaries, as described in the
1606 // processor specific ABI supplement.
1607
1608 uint64_t
1609 Target_x86_64::do_dynsym_value(const Symbol* gsym) const
1610 {
1611   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1612   return this->plt_section()->address() + gsym->plt_offset();
1613 }
1614
1615 // Return a string used to fill a code section with nops to take up
1616 // the specified length.
1617
1618 std::string
1619 Target_x86_64::do_code_fill(off_t length)
1620 {
1621   if (length >= 16)
1622     {
1623       // Build a jmpq instruction to skip over the bytes.
1624       unsigned char jmp[5];
1625       jmp[0] = 0xe9;
1626       elfcpp::Swap_unaligned<64, false>::writeval(jmp + 1, length - 5);
1627       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1628               + std::string(length - 5, '\0'));
1629     }
1630
1631   // Nop sequences of various lengths.
1632   const char nop1[1] = { 0x90 };                   // nop
1633   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1634   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1635   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1636   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1637                          0x00 };                   // leal 0(%esi,1),%esi
1638   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1639                          0x00, 0x00 };
1640   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1641                          0x00, 0x00, 0x00 };
1642   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1643                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1644   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1645                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1646                          0x00 };
1647   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1648                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1649                            0x00, 0x00 };
1650   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1651                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1652                            0x00, 0x00, 0x00 };
1653   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1654                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1655                            0x00, 0x00, 0x00, 0x00 };
1656   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1657                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1658                            0x27, 0x00, 0x00, 0x00,
1659                            0x00 };
1660   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1661                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1662                            0xbc, 0x27, 0x00, 0x00,
1663                            0x00, 0x00 };
1664   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1665                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1666                            0x90, 0x90, 0x90, 0x90,
1667                            0x90, 0x90, 0x90 };
1668
1669   const char* nops[16] = {
1670     NULL,
1671     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1672     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1673   };
1674
1675   return std::string(nops[length], length);
1676 }
1677
1678 // The selector for x86_64 object files.
1679
1680 class Target_selector_x86_64 : public Target_selector
1681 {
1682 public:
1683   Target_selector_x86_64()
1684     : Target_selector(elfcpp::EM_X86_64, 64, false)
1685   { }
1686
1687   Target*
1688   recognize(int machine, int osabi, int abiversion);
1689
1690  private:
1691   Target_x86_64* target_;
1692 };
1693
1694 // Recognize an x86_64 object file when we already know that the machine
1695 // number is EM_X86_64.
1696
1697 Target*
1698 Target_selector_x86_64::recognize(int, int, int)
1699 {
1700   if (this->target_ == NULL)
1701     this->target_ = new Target_x86_64();
1702   return this->target_;
1703 }
1704
1705 Target_selector_x86_64 target_selector_x86_64;
1706
1707 } // End anonymous namespace.