gold/i386.cc

   1 // i386.cc -- i386 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 modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #include "gold.h"
  24
  25 #include <cstring>
  26
  27 #include "elfcpp.h"
  28 #include "parameters.h"
  29 #include "reloc.h"
  30 #include "i386.h"
  31 #include "object.h"
  32 #include "symtab.h"
  33 #include "layout.h"
  34 #include "output.h"
  35 #include "target.h"
  36 #include "target-reloc.h"
  37 #include "target-select.h"
  38 #include "tls.h"
  39
  40 namespace
  41 {
  42
  43 using namespace gold;
  44
  45 class Output_data_plt_i386;
  46
  47 // The i386 target class.
  48 // TLS info comes from
  49 //   http://people.redhat.com/drepper/tls.pdf
  50 //   http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
  51
  52 class Target_i386 : public Sized_target<32, false>
  53 {
  54  public:
  55   typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
  56
  57   Target_i386()
  58     : Sized_target<32, false>(&i386_info),
  59       got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
  60       copy_relocs_(NULL), dynbss_(NULL)
  61   { }
  62
  63   // Scan the relocations to look for symbol adjustments.
  64   void
  65   scan_relocs(const General_options& options,
  66               Symbol_table* symtab,
  67               Layout* layout,
  68               Sized_relobj<32, false>* object,
  69               unsigned int data_shndx,
  70               unsigned int sh_type,
  71               const unsigned char* prelocs,
  72               size_t reloc_count,
  73               size_t local_symbol_count,
  74               const unsigned char* plocal_symbols,
  75               Symbol** global_symbols);
  76
  77   // Finalize the sections.
  78   void
  79   do_finalize_sections(Layout*);
  80
  81   // Return the value to use for a dynamic which requires special
  82   // treatment.
  83   uint64_t
  84   do_dynsym_value(const Symbol*) const;
  85
  86   // Relocate a section.
  87   void
  88   relocate_section(const Relocate_info<32, false>*,
  89                    unsigned int sh_type,
  90                    const unsigned char* prelocs,
  91                    size_t reloc_count,
  92                    unsigned char* view,
  93                    elfcpp::Elf_types<32>::Elf_Addr view_address,
  94                    off_t view_size);
  95
  96   // Return a string used to fill a code section with nops.
  97   std::string
  98   do_code_fill(off_t length);
  99
 100  private:
 101   // The class which scans relocations.
 102   struct Scan
 103   {
 104     inline void
 105     local(const General_options& options, Symbol_table* symtab,
 106           Layout* layout, Target_i386* target,
 107           Sized_relobj<32, false>* object,
 108           unsigned int data_shndx,
 109           const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
 110           const elfcpp::Sym<32, false>& lsym);
 111
 112     inline void
 113     global(const General_options& options, Symbol_table* symtab,
 114            Layout* layout, Target_i386* target,
 115            Sized_relobj<32, false>* object,
 116            unsigned int data_shndx,
 117            const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
 118            Symbol* gsym);
 119
 120     static void
 121     unsupported_reloc_local(Sized_relobj<32, false>*, unsigned int r_type);
 122
 123     static void
 124     unsupported_reloc_global(Sized_relobj<32, false>*, unsigned int r_type,
 125                              Symbol*);
 126   };
 127
 128   // The class which implements relocation.
 129   class Relocate
 130   {
 131    public:
 132     Relocate()
 133       : skip_call_tls_get_addr_(false),
 134         local_dynamic_type_(LOCAL_DYNAMIC_NONE)
 135     { }
 136
 137     ~Relocate()
 138     {
 139       if (this->skip_call_tls_get_addr_)
 140         {
 141           // FIXME: This needs to specify the location somehow.
 142           fprintf(stderr, _("%s: missing expected TLS relocation\n"),
 143                   program_name);
 144           gold_exit(false);
 145         }
 146     }
 147
 148     // Do a relocation.  Return false if the caller should not issue
 149     // any warnings about this relocation.
 150     inline bool
 151     relocate(const Relocate_info<32, false>*, Target_i386*, size_t relnum,
 152              const elfcpp::Rel<32, false>&,
 153              unsigned int r_type, const Sized_symbol<32>*,
 154              const Symbol_value<32>*,
 155              unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
 156              off_t);
 157
 158    private:
 159     // Do a TLS relocation.
 160     inline void
 161     relocate_tls(const Relocate_info<32, false>*, size_t relnum,
 162                  const elfcpp::Rel<32, false>&,
 163                  unsigned int r_type, const Sized_symbol<32>*,
 164                  const Symbol_value<32>*,
 165                  unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, off_t);
 166
 167     // Do a TLS Initial-Exec to Local-Exec transition.
 168     static inline void
 169     tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum,
 170                  Output_segment* tls_segment,
 171                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 172                  elfcpp::Elf_types<32>::Elf_Addr value,
 173                  unsigned char* view,
 174                  off_t view_size);
 175
 176     // Do a TLS General-Dynamic to Local-Exec transition.
 177     inline void
 178     tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
 179                  Output_segment* tls_segment,
 180                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 181                  elfcpp::Elf_types<32>::Elf_Addr value,
 182                  unsigned char* view,
 183                  off_t view_size);
 184
 185     // Do a TLS Local-Dynamic to Local-Exec transition.
 186     inline void
 187     tls_ld_to_le(const Relocate_info<32, false>*, size_t relnum,
 188                  Output_segment* tls_segment,
 189                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 190                  elfcpp::Elf_types<32>::Elf_Addr value,
 191                  unsigned char* view,
 192                  off_t view_size);
 193
 194     // We need to keep track of which type of local dynamic relocation
 195     // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
 196     enum Local_dynamic_type
 197     {
 198       LOCAL_DYNAMIC_NONE,
 199       LOCAL_DYNAMIC_SUN,
 200       LOCAL_DYNAMIC_GNU
 201     };
 202
 203     // This is set if we should skip the next reloc, which should be a
 204     // PLT32 reloc against ___tls_get_addr.
 205     bool skip_call_tls_get_addr_;
 206     // The type of local dynamic relocation we have seen in the section
 207     // being relocated, if any.
 208     Local_dynamic_type local_dynamic_type_;
 209   };
 210
 211   // Adjust TLS relocation type based on the options and whether this
 212   // is a local symbol.
 213   static tls::Tls_optimization
 214   optimize_tls_reloc(bool is_final, int r_type);
 215
 216   // Get the GOT section, creating it if necessary.
 217   Output_data_got<32, false>*
 218   got_section(Symbol_table*, Layout*);
 219
 220   // Create a PLT entry for a global symbol.
 221   void
 222   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 223
 224   // Get the PLT section.
 225   const Output_data_plt_i386*
 226   plt_section() const
 227   {
 228     gold_assert(this->plt_ != NULL);
 229     return this->plt_;
 230   }
 231
 232   // Get the dynamic reloc section, creating it if necessary.
 233   Reloc_section*
 234   rel_dyn_section(Layout*);
 235
 236   // Copy a relocation against a global symbol.
 237   void
 238   copy_reloc(const General_options*, Symbol_table*, Layout*,
 239              Sized_relobj<32, false>*, unsigned int,
 240              Symbol*, const elfcpp::Rel<32, false>&);
 241
 242   // Information about this specific target which we pass to the
 243   // general Target structure.
 244   static const Target::Target_info i386_info;
 245
 246   // The GOT section.
 247   Output_data_got<32, false>* got_;
 248   // The PLT section.
 249   Output_data_plt_i386* plt_;
 250   // The GOT PLT section.
 251   Output_data_space* got_plt_;
 252   // The dynamic reloc section.
 253   Reloc_section* rel_dyn_;
 254   // Relocs saved to avoid a COPY reloc.
 255   Copy_relocs<32, false>* copy_relocs_;
 256   // Space for variables copied with a COPY reloc.
 257   Output_data_space* dynbss_;
 258 };
 259
 260 const Target::Target_info Target_i386::i386_info =
 261 {
 262   32,                   // size
 263   false,                // is_big_endian
 264   elfcpp::EM_386,       // machine_code
 265   false,                // has_make_symbol
 266   false,                // has_resolve
 267   true,                 // has_code_fill
 268   "/usr/lib/libc.so.1", // dynamic_linker
 269   0x08048000,           // text_segment_address
 270   0x1000,               // abi_pagesize
 271   0x1000                // common_pagesize
 272 };
 273
 274 // Get the GOT section, creating it if necessary.
 275
 276 Output_data_got<32, false>*
 277 Target_i386::got_section(Symbol_table* symtab, Layout* layout)
 278 {
 279   if (this->got_ == NULL)
 280     {
 281       gold_assert(symtab != NULL && layout != NULL);
 282
 283       this->got_ = new Output_data_got<32, false>();
 284
 285       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 286                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 287                                       this->got_);
 288
 289       // The old GNU linker creates a .got.plt section.  We just
 290       // create another set of data in the .got section.  Note that we
 291       // always create a PLT if we create a GOT, although the PLT
 292       // might be empty.
 293       this->got_plt_ = new Output_data_space(4);
 294       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 295                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 296                                       this->got_plt_);
 297
 298       // The first three entries are reserved.
 299       this->got_plt_->set_space_size(3 * 4);
 300
 301       // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
 302       symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
 303                                     this->got_plt_,
 304                                     0, 0, elfcpp::STT_OBJECT,
 305                                     elfcpp::STB_LOCAL,
 306                                     elfcpp::STV_HIDDEN, 0,
 307                                     false, false);
 308     }
 309
 310   return this->got_;
 311 }
 312
 313 // Get the dynamic reloc section, creating it if necessary.
 314
 315 Target_i386::Reloc_section*
 316 Target_i386::rel_dyn_section(Layout* layout)
 317 {
 318   if (this->rel_dyn_ == NULL)
 319     {
 320       gold_assert(layout != NULL);
 321       this->rel_dyn_ = new Reloc_section();
 322       layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
 323                                       elfcpp::SHF_ALLOC, this->rel_dyn_);
 324     }
 325   return this->rel_dyn_;
 326 }
 327
 328 // A class to handle the PLT data.
 329
 330 class Output_data_plt_i386 : public Output_section_data
 331 {
 332  public:
 333   typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
 334
 335   Output_data_plt_i386(Layout*, Output_data_space*);
 336
 337   // Add an entry to the PLT.
 338   void
 339   add_entry(Symbol* gsym);
 340
 341   // Return the .rel.plt section data.
 342   const Reloc_section*
 343   rel_plt() const
 344   { return this->rel_; }
 345
 346  protected:
 347   void
 348   do_adjust_output_section(Output_section* os);
 349
 350  private:
 351   // The size of an entry in the PLT.
 352   static const int plt_entry_size = 16;
 353
 354   // The first entry in the PLT for an executable.
 355   static unsigned char exec_first_plt_entry[plt_entry_size];
 356
 357   // The first entry in the PLT for a shared object.
 358   static unsigned char dyn_first_plt_entry[plt_entry_size];
 359
 360   // Other entries in the PLT for an executable.
 361   static unsigned char exec_plt_entry[plt_entry_size];
 362
 363   // Other entries in the PLT for a shared object.
 364   static unsigned char dyn_plt_entry[plt_entry_size];
 365
 366   // Set the final size.
 367   void
 368   do_set_address(uint64_t, off_t)
 369   { this->set_data_size((this->count_ + 1) * plt_entry_size); }
 370
 371   // Write out the PLT data.
 372   void
 373   do_write(Output_file*);
 374
 375   // The reloc section.
 376   Reloc_section* rel_;
 377   // The .got.plt section.
 378   Output_data_space* got_plt_;
 379   // The number of PLT entries.
 380   unsigned int count_;
 381 };
 382
 383 // Create the PLT section.  The ordinary .got section is an argument,
 384 // since we need to refer to the start.  We also create our own .got
 385 // section just for PLT entries.
 386
 387 Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
 388                                            Output_data_space* got_plt)
 389   : Output_section_data(4), got_plt_(got_plt), count_(0)
 390 {
 391   this->rel_ = new Reloc_section();
 392   layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
 393                                   elfcpp::SHF_ALLOC, this->rel_);
 394 }
 395
 396 void
 397 Output_data_plt_i386::do_adjust_output_section(Output_section* os)
 398 {
 399   // UnixWare sets the entsize of .plt to 4, and so does the old GNU
 400   // linker, and so do we.
 401   os->set_entsize(4);
 402 }
 403
 404 // Add an entry to the PLT.
 405
 406 void
 407 Output_data_plt_i386::add_entry(Symbol* gsym)
 408 {
 409   gold_assert(!gsym->has_plt_offset());
 410
 411   // Note that when setting the PLT offset we skip the initial
 412   // reserved PLT entry.
 413   gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
 414
 415   ++this->count_;
 416
 417   off_t got_offset = this->got_plt_->data_size();
 418
 419   // Every PLT entry needs a GOT entry which points back to the PLT
 420   // entry (this will be changed by the dynamic linker, normally
 421   // lazily when the function is called).
 422   this->got_plt_->set_space_size(got_offset + 4);
 423
 424   // Every PLT entry needs a reloc.
 425   gsym->set_needs_dynsym_entry();
 426   this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_,
 427                          got_offset);
 428
 429   // Note that we don't need to save the symbol.  The contents of the
 430   // PLT are independent of which symbols are used.  The symbols only
 431   // appear in the relocations.
 432 }
 433
 434 // The first entry in the PLT for an executable.
 435
 436 unsigned char Output_data_plt_i386::exec_first_plt_entry[plt_entry_size] =
 437 {
 438   0xff, 0x35,   // pushl contents of memory address
 439   0, 0, 0, 0,   // replaced with address of .got + 4
 440   0xff, 0x25,   // jmp indirect
 441   0, 0, 0, 0,   // replaced with address of .got + 8
 442   0, 0, 0, 0    // unused
 443 };
 444
 445 // The first entry in the PLT for a shared object.
 446
 447 unsigned char Output_data_plt_i386::dyn_first_plt_entry[plt_entry_size] =
 448 {
 449   0xff, 0xb3, 4, 0, 0, 0,       // pushl 4(%ebx)
 450   0xff, 0xa3, 8, 0, 0, 0,       // jmp *8(%ebx)
 451   0, 0, 0, 0                    // unused
 452 };
 453
 454 // Subsequent entries in the PLT for an executable.
 455
 456 unsigned char Output_data_plt_i386::exec_plt_entry[plt_entry_size] =
 457 {
 458   0xff, 0x25,   // jmp indirect
 459   0, 0, 0, 0,   // replaced with address of symbol in .got
 460   0x68,         // pushl immediate
 461   0, 0, 0, 0,   // replaced with offset into relocation table
 462   0xe9,         // jmp relative
 463   0, 0, 0, 0    // replaced with offset to start of .plt
 464 };
 465
 466 // Subsequent entries in the PLT for a shared object.
 467
 468 unsigned char Output_data_plt_i386::dyn_plt_entry[plt_entry_size] =
 469 {
 470   0xff, 0xa3,   // jmp *offset(%ebx)
 471   0, 0, 0, 0,   // replaced with offset of symbol in .got
 472   0x68,         // pushl immediate
 473   0, 0, 0, 0,   // replaced with offset into relocation table
 474   0xe9,         // jmp relative
 475   0, 0, 0, 0    // replaced with offset to start of .plt
 476 };
 477
 478 // Write out the PLT.  This uses the hand-coded instructions above,
 479 // and adjusts them as needed.  This is all specified by the i386 ELF
 480 // Processor Supplement.
 481
 482 void
 483 Output_data_plt_i386::do_write(Output_file* of)
 484 {
 485   const off_t offset = this->offset();
 486   const off_t oview_size = this->data_size();
 487   unsigned char* const oview = of->get_output_view(offset, oview_size);
 488
 489   const off_t got_file_offset = this->got_plt_->offset();
 490   const off_t got_size = this->got_plt_->data_size();
 491   unsigned char* const got_view = of->get_output_view(got_file_offset,
 492                                                       got_size);
 493
 494   unsigned char* pov = oview;
 495
 496   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
 497   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 498
 499   if (parameters->output_is_shared())
 500     memcpy(pov, dyn_first_plt_entry, plt_entry_size);
 501   else
 502     {
 503       memcpy(pov, exec_first_plt_entry, plt_entry_size);
 504       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
 505       elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
 506     }
 507   pov += plt_entry_size;
 508
 509   unsigned char* got_pov = got_view;
 510
 511   memset(got_pov, 0, 12);
 512   got_pov += 12;
 513
 514   const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
 515
 516   unsigned int plt_offset = plt_entry_size;
 517   unsigned int plt_rel_offset = 0;
 518   unsigned int got_offset = 12;
 519   const unsigned int count = this->count_;
 520   for (unsigned int i = 0;
 521        i < count;
 522        ++i,
 523          pov += plt_entry_size,
 524          got_pov += 4,
 525          plt_offset += plt_entry_size,
 526          plt_rel_offset += rel_size,
 527          got_offset += 4)
 528     {
 529       // Set and adjust the PLT entry itself.
 530
 531       if (parameters->output_is_shared())
 532         {
 533           memcpy(pov, dyn_plt_entry, plt_entry_size);
 534           elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
 535         }
 536       else
 537         {
 538           memcpy(pov, exec_plt_entry, plt_entry_size);
 539           elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 540                                                       (got_address
 541                                                        + got_offset));
 542         }
 543
 544       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
 545       elfcpp::Swap<32, false>::writeval(pov + 12,
 546                                         - (plt_offset + plt_entry_size));
 547
 548       // Set the entry in the GOT.
 549       elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6);
 550     }
 551
 552   gold_assert(pov - oview == oview_size);
 553   gold_assert(got_pov - got_view == got_size);
 554
 555   of->write_output_view(offset, oview_size, oview);
 556   of->write_output_view(got_file_offset, got_size, got_view);
 557 }
 558
 559 // Create a PLT entry for a global symbol.
 560
 561 void
 562 Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym)
 563 {
 564   if (gsym->has_plt_offset())
 565     return;
 566
 567   if (this->plt_ == NULL)
 568     {
 569       // Create the GOT sections first.
 570       this->got_section(symtab, layout);
 571
 572       this->plt_ = new Output_data_plt_i386(layout, this->got_plt_);
 573       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 574                                       (elfcpp::SHF_ALLOC
 575                                        | elfcpp::SHF_EXECINSTR),
 576                                       this->plt_);
 577     }
 578
 579   this->plt_->add_entry(gsym);
 580 }
 581
 582 // Handle a relocation against a non-function symbol defined in a
 583 // dynamic object.  The traditional way to handle this is to generate
 584 // a COPY relocation to copy the variable at runtime from the shared
 585 // object into the executable's data segment.  However, this is
 586 // undesirable in general, as if the size of the object changes in the
 587 // dynamic object, the executable will no longer work correctly.  If
 588 // this relocation is in a writable section, then we can create a
 589 // dynamic reloc and the dynamic linker will resolve it to the correct
 590 // address at runtime.  However, we do not want do that if the
 591 // relocation is in a read-only section, as it would prevent the
 592 // readonly segment from being shared.  And if we have to eventually
 593 // generate a COPY reloc, then any dynamic relocations will be
 594 // useless.  So this means that if this is a writable section, we need
 595 // to save the relocation until we see whether we have to create a
 596 // COPY relocation for this symbol for any other relocation.
 597
 598 void
 599 Target_i386::copy_reloc(const General_options* options,
 600                         Symbol_table* symtab,
 601                         Layout* layout,
 602                         Sized_relobj<32, false>* object,
 603                         unsigned int data_shndx, Symbol* gsym,
 604                         const elfcpp::Rel<32, false>& rel)
 605 {
 606   Sized_symbol<32>* ssym;
 607   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(32) (gsym
 608                                                         SELECT_SIZE(32));
 609
 610   if (!Copy_relocs<32, false>::need_copy_reloc(options, object,
 611                                                data_shndx, ssym))
 612     {
 613       // So far we do not need a COPY reloc.  Save this relocation.
 614       // If it turns out that we never need a COPY reloc for this
 615       // symbol, then we will emit the relocation.
 616       if (this->copy_relocs_ == NULL)
 617         this->copy_relocs_ = new Copy_relocs<32, false>();
 618       this->copy_relocs_->save(ssym, object, data_shndx, rel);
 619     }
 620   else
 621     {
 622       // Allocate space for this symbol in the .bss section.
 623
 624       elfcpp::Elf_types<32>::Elf_WXword symsize = ssym->symsize();
 625
 626       // There is no defined way to determine the required alignment
 627       // of the symbol.  We pick the alignment based on the size.  We
 628       // set an arbitrary maximum of 256.
 629       unsigned int align;
 630       for (align = 1; align < 512; align <<= 1)
 631         if ((symsize & align) != 0)
 632           break;
 633
 634       if (this->dynbss_ == NULL)
 635         {
 636           this->dynbss_ = new Output_data_space(align);
 637           layout->add_output_section_data(".bss",
 638                                           elfcpp::SHT_NOBITS,
 639                                           (elfcpp::SHF_ALLOC
 640                                            | elfcpp::SHF_WRITE),
 641                                           this->dynbss_);
 642         }
 643
 644       Output_data_space* dynbss = this->dynbss_;
 645
 646       if (align > dynbss->addralign())
 647         dynbss->set_space_alignment(align);
 648
 649       off_t dynbss_size = dynbss->data_size();
 650       dynbss_size = align_address(dynbss_size, align);
 651       off_t offset = dynbss_size;
 652       dynbss->set_space_size(dynbss_size + symsize);
 653
 654       // Define the symbol in the .dynbss section.
 655       symtab->define_in_output_data(this, ssym->name(), ssym->version(),
 656                                     dynbss, offset, symsize, ssym->type(),
 657                                     ssym->binding(), ssym->visibility(),
 658                                     ssym->nonvis(), false, false);
 659
 660       // Add the COPY reloc.
 661       ssym->set_needs_dynsym_entry();
 662       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
 663       rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset);
 664     }
 665 }
 666
 667 // Optimize the TLS relocation type based on what we know about the
 668 // symbol.  IS_FINAL is true if the final address of this symbol is
 669 // known at link time.
 670
 671 tls::Tls_optimization
 672 Target_i386::optimize_tls_reloc(bool is_final, int r_type)
 673 {
 674   // If we are generating a shared library, then we can't do anything
 675   // in the linker.
 676   if (parameters->output_is_shared())
 677     return tls::TLSOPT_NONE;
 678
 679   switch (r_type)
 680     {
 681     case elfcpp::R_386_TLS_GD:
 682     case elfcpp::R_386_TLS_GOTDESC:
 683     case elfcpp::R_386_TLS_DESC_CALL:
 684       // These are General-Dynamic which permits fully general TLS
 685       // access.  Since we know that we are generating an executable,
 686       // we can convert this to Initial-Exec.  If we also know that
 687       // this is a local symbol, we can further switch to Local-Exec.
 688       if (is_final)
 689         return tls::TLSOPT_TO_LE;
 690       return tls::TLSOPT_TO_IE;
 691
 692     case elfcpp::R_386_TLS_LDM:
 693       // This is Local-Dynamic, which refers to a local symbol in the
 694       // dynamic TLS block.  Since we know that we generating an
 695       // executable, we can switch to Local-Exec.
 696       return tls::TLSOPT_TO_LE;
 697
 698     case elfcpp::R_386_TLS_LDO_32:
 699       // Another type of Local-Dynamic relocation.
 700       return tls::TLSOPT_TO_LE;
 701
 702     case elfcpp::R_386_TLS_IE:
 703     case elfcpp::R_386_TLS_GOTIE:
 704     case elfcpp::R_386_TLS_IE_32:
 705       // These are Initial-Exec relocs which get the thread offset
 706       // from the GOT.  If we know that we are linking against the
 707       // local symbol, we can switch to Local-Exec, which links the
 708       // thread offset into the instruction.
 709       if (is_final)
 710         return tls::TLSOPT_TO_LE;
 711       return tls::TLSOPT_NONE;
 712
 713     case elfcpp::R_386_TLS_LE:
 714     case elfcpp::R_386_TLS_LE_32:
 715       // When we already have Local-Exec, there is nothing further we
 716       // can do.
 717       return tls::TLSOPT_NONE;
 718
 719     default:
 720       gold_unreachable();
 721     }
 722 }
 723
 724 // Report an unsupported relocation against a local symbol.
 725
 726 void
 727 Target_i386::Scan::unsupported_reloc_local(Sized_relobj<32, false>* object,
 728                                            unsigned int r_type)
 729 {
 730   fprintf(stderr, _("%s: %s: unsupported reloc %u against local symbol\n"),
 731           program_name, object->name().c_str(), r_type);
 732 }
 733
 734 // Scan a relocation for a local symbol.
 735
 736 inline void
 737 Target_i386::Scan::local(const General_options&,
 738                          Symbol_table* symtab,
 739                          Layout* layout,
 740                          Target_i386* target,
 741                          Sized_relobj<32, false>* object,
 742                          unsigned int,
 743                          const elfcpp::Rel<32, false>&,
 744                          unsigned int r_type,
 745                          const elfcpp::Sym<32, false>&)
 746 {
 747   switch (r_type)
 748     {
 749     case elfcpp::R_386_NONE:
 750     case elfcpp::R_386_GNU_VTINHERIT:
 751     case elfcpp::R_386_GNU_VTENTRY:
 752       break;
 753
 754     case elfcpp::R_386_32:
 755     case elfcpp::R_386_16:
 756     case elfcpp::R_386_8:
 757       // FIXME: If we are generating a shared object we need to copy
 758       // this relocation into the object.
 759       gold_assert(!parameters->output_is_shared());
 760       break;
 761
 762     case elfcpp::R_386_PC32:
 763     case elfcpp::R_386_PC16:
 764     case elfcpp::R_386_PC8:
 765       break;
 766
 767     case elfcpp::R_386_GOTOFF:
 768     case elfcpp::R_386_GOTPC:
 769       // We need a GOT section.
 770       target->got_section(symtab, layout);
 771       break;
 772
 773       // These are relocations which should only be seen by the
 774       // dynamic linker, and should never be seen here.
 775     case elfcpp::R_386_COPY:
 776     case elfcpp::R_386_GLOB_DAT:
 777     case elfcpp::R_386_JUMP_SLOT:
 778     case elfcpp::R_386_RELATIVE:
 779     case elfcpp::R_386_TLS_TPOFF:
 780     case elfcpp::R_386_TLS_DTPMOD32:
 781     case elfcpp::R_386_TLS_DTPOFF32:
 782     case elfcpp::R_386_TLS_TPOFF32:
 783     case elfcpp::R_386_TLS_DESC:
 784       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
 785               program_name, object->name().c_str(), r_type);
 786       gold_exit(false);
 787       break;
 788
 789       // These are initial TLS relocs, which are expected when
 790       // linking.
 791     case elfcpp::R_386_TLS_IE:
 792     case elfcpp::R_386_TLS_GOTIE:
 793     case elfcpp::R_386_TLS_LE:
 794     case elfcpp::R_386_TLS_GD:
 795     case elfcpp::R_386_TLS_LDM:
 796     case elfcpp::R_386_TLS_LDO_32:
 797     case elfcpp::R_386_TLS_IE_32:
 798     case elfcpp::R_386_TLS_LE_32:
 799     case elfcpp::R_386_TLS_GOTDESC:
 800     case elfcpp::R_386_TLS_DESC_CALL:
 801       {
 802         bool output_is_shared = parameters->output_is_shared();
 803         const tls::Tls_optimization optimized_type
 804             = Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
 805         switch (r_type)
 806           {
 807           case elfcpp::R_386_TLS_LE:
 808           case elfcpp::R_386_TLS_LE_32:
 809             // FIXME: If generating a shared object, we need to copy
 810             // this relocation into the object.
 811             gold_assert(!output_is_shared);
 812             break;
 813
 814           case elfcpp::R_386_TLS_IE:
 815           case elfcpp::R_386_TLS_IE_32:
 816           case elfcpp::R_386_TLS_GOTIE:
 817             // FIXME: If not relaxing to LE, we need to generate a
 818             // TPOFF or TPOFF32 reloc.
 819             if (optimized_type != tls::TLSOPT_TO_LE)
 820               unsupported_reloc_local(object, r_type);
 821             break;
 822
 823           case elfcpp::R_386_TLS_LDM:
 824             // FIXME: If not relaxing to LE, we need to generate a
 825             // DTPMOD32 reloc.
 826             if (optimized_type != tls::TLSOPT_TO_LE)
 827               unsupported_reloc_local(object, r_type);
 828             break;
 829
 830           case elfcpp::R_386_TLS_LDO_32:
 831             break;
 832
 833           case elfcpp::R_386_TLS_GD:
 834           case elfcpp::R_386_TLS_GOTDESC:
 835           case elfcpp::R_386_TLS_DESC_CALL:
 836             // FIXME: If not relaxing to LE, we need to generate
 837             // DTPMOD32 and DTPOFF32 relocs.
 838             if (optimized_type != tls::TLSOPT_TO_LE)
 839               unsupported_reloc_local(object, r_type);
 840             break;
 841
 842           default:
 843             gold_unreachable();
 844           }
 845       }
 846       break;
 847
 848     case elfcpp::R_386_GOT32:
 849     case elfcpp::R_386_PLT32:
 850     case elfcpp::R_386_32PLT:
 851     case elfcpp::R_386_TLS_GD_32:
 852     case elfcpp::R_386_TLS_GD_PUSH:
 853     case elfcpp::R_386_TLS_GD_CALL:
 854     case elfcpp::R_386_TLS_GD_POP:
 855     case elfcpp::R_386_TLS_LDM_32:
 856     case elfcpp::R_386_TLS_LDM_PUSH:
 857     case elfcpp::R_386_TLS_LDM_CALL:
 858     case elfcpp::R_386_TLS_LDM_POP:
 859     case elfcpp::R_386_USED_BY_INTEL_200:
 860     default:
 861       unsupported_reloc_local(object, r_type);
 862       break;
 863     }
 864 }
 865
 866 // Report an unsupported relocation against a global symbol.
 867
 868 void
 869 Target_i386::Scan::unsupported_reloc_global(Sized_relobj<32, false>* object,
 870                                             unsigned int r_type,
 871                                             Symbol* gsym)
 872 {
 873   fprintf(stderr,
 874           _("%s: %s: unsupported reloc %u against global symbol %s\n"),
 875           program_name, object->name().c_str(), r_type, gsym->name());
 876 }
 877
 878 // Scan a relocation for a global symbol.
 879
 880 inline void
 881 Target_i386::Scan::global(const General_options& options,
 882                           Symbol_table* symtab,
 883                           Layout* layout,
 884                           Target_i386* target,
 885                           Sized_relobj<32, false>* object,
 886                           unsigned int data_shndx,
 887                           const elfcpp::Rel<32, false>& reloc,
 888                           unsigned int r_type,
 889                           Symbol* gsym)
 890 {
 891   switch (r_type)
 892     {
 893     case elfcpp::R_386_NONE:
 894     case elfcpp::R_386_GNU_VTINHERIT:
 895     case elfcpp::R_386_GNU_VTENTRY:
 896       break;
 897
 898     case elfcpp::R_386_32:
 899     case elfcpp::R_386_PC32:
 900     case elfcpp::R_386_16:
 901     case elfcpp::R_386_PC16:
 902     case elfcpp::R_386_8:
 903     case elfcpp::R_386_PC8:
 904       // FIXME: If we are generating a shared object we may need to
 905       // copy this relocation into the object.  If this symbol is
 906       // defined in a shared object, we may need to copy this
 907       // relocation in order to avoid a COPY relocation.
 908       gold_assert(!parameters->output_is_shared());
 909
 910       if (gsym->is_from_dynobj())
 911         {
 912           // This symbol is defined in a dynamic object.  If it is a
 913           // function, we make a PLT entry.  Otherwise we need to
 914           // either generate a COPY reloc or copy this reloc.
 915           if (gsym->type() == elfcpp::STT_FUNC)
 916             {
 917               target->make_plt_entry(symtab, layout, gsym);
 918
 919               // If this is not a PC relative reference, then we may
 920               // be taking the address of the function.  In that case
 921               // we need to set the entry in the dynamic symbol table
 922               // to the address of the PLT entry.
 923               if (r_type != elfcpp::R_386_PC32
 924                   && r_type != elfcpp::R_386_PC16
 925                   && r_type != elfcpp::R_386_PC8)
 926                 gsym->set_needs_dynsym_value();
 927             }
 928           else
 929             target->copy_reloc(&options, symtab, layout, object, data_shndx,
 930                                gsym, reloc);
 931         }
 932
 933       break;
 934
 935     case elfcpp::R_386_GOT32:
 936       {
 937         // The symbol requires a GOT entry.
 938         Output_data_got<32, false>* got = target->got_section(symtab, layout);
 939         if (got->add_global(gsym))
 940           {
 941             // If this symbol is not fully resolved, we need to add a
 942             // dynamic relocation for it.
 943             if (!gsym->final_value_is_known())
 944               {
 945                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 946                 rel_dyn->add_global(gsym, elfcpp::R_386_GLOB_DAT, got,
 947                                     gsym->got_offset());
 948               }
 949           }
 950       }
 951       break;
 952
 953     case elfcpp::R_386_PLT32:
 954       // If the symbol is fully resolved, this is just a PC32 reloc.
 955       // Otherwise we need a PLT entry.
 956       if (gsym->final_value_is_known())
 957         break;
 958       target->make_plt_entry(symtab, layout, gsym);
 959       break;
 960
 961     case elfcpp::R_386_GOTOFF:
 962     case elfcpp::R_386_GOTPC:
 963       // We need a GOT section.
 964       target->got_section(symtab, layout);
 965       break;
 966
 967       // These are relocations which should only be seen by the
 968       // dynamic linker, and should never be seen here.
 969     case elfcpp::R_386_COPY:
 970     case elfcpp::R_386_GLOB_DAT:
 971     case elfcpp::R_386_JUMP_SLOT:
 972     case elfcpp::R_386_RELATIVE:
 973     case elfcpp::R_386_TLS_TPOFF:
 974     case elfcpp::R_386_TLS_DTPMOD32:
 975     case elfcpp::R_386_TLS_DTPOFF32:
 976     case elfcpp::R_386_TLS_TPOFF32:
 977     case elfcpp::R_386_TLS_DESC:
 978       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
 979               program_name, object->name().c_str(), r_type);
 980       gold_exit(false);
 981       break;
 982
 983       // These are initial tls relocs, which are expected when
 984       // linking.
 985     case elfcpp::R_386_TLS_IE:
 986     case elfcpp::R_386_TLS_GOTIE:
 987     case elfcpp::R_386_TLS_LE:
 988     case elfcpp::R_386_TLS_GD:
 989     case elfcpp::R_386_TLS_LDM:
 990     case elfcpp::R_386_TLS_LDO_32:
 991     case elfcpp::R_386_TLS_IE_32:
 992     case elfcpp::R_386_TLS_LE_32:
 993     case elfcpp::R_386_TLS_GOTDESC:
 994     case elfcpp::R_386_TLS_DESC_CALL:
 995       {
 996         const bool is_final = gsym->final_value_is_known();
 997         const tls::Tls_optimization optimized_type
 998             = Target_i386::optimize_tls_reloc(is_final, r_type);
 999         switch (r_type)
1000           {
1001           case elfcpp::R_386_TLS_LE:
1002           case elfcpp::R_386_TLS_LE_32:
1003             // FIXME: If generating a shared object, we need to copy
1004             // this relocation into the object.
1005             gold_assert(!parameters->output_is_shared());
1006             break;
1007
1008           case elfcpp::R_386_TLS_IE:
1009           case elfcpp::R_386_TLS_IE_32:
1010           case elfcpp::R_386_TLS_GOTIE:
1011             // FIXME: If not relaxing to LE, we need to generate a
1012             // TPOFF or TPOFF32 reloc.
1013             if (optimized_type != tls::TLSOPT_TO_LE)
1014               unsupported_reloc_global(object, r_type, gsym);
1015             break;
1016
1017           case elfcpp::R_386_TLS_LDM:
1018             // FIXME: If not relaxing to LE, we need to generate a
1019             // DTPMOD32 reloc.
1020             if (optimized_type != tls::TLSOPT_TO_LE)
1021               unsupported_reloc_global(object, r_type, gsym);
1022             break;
1023
1024           case elfcpp::R_386_TLS_LDO_32:
1025             break;
1026
1027           case elfcpp::R_386_TLS_GD:
1028           case elfcpp::R_386_TLS_GOTDESC:
1029           case elfcpp::R_386_TLS_DESC_CALL:
1030             // FIXME: If not relaxing to LE, we need to generate
1031             // DTPMOD32 and DTPOFF32 relocs.
1032             if (optimized_type != tls::TLSOPT_TO_LE)
1033               unsupported_reloc_global(object, r_type, gsym);
1034             break;
1035
1036           default:
1037             gold_unreachable();
1038           }
1039       }
1040       break;
1041
1042     case elfcpp::R_386_32PLT:
1043     case elfcpp::R_386_TLS_GD_32:
1044     case elfcpp::R_386_TLS_GD_PUSH:
1045     case elfcpp::R_386_TLS_GD_CALL:
1046     case elfcpp::R_386_TLS_GD_POP:
1047     case elfcpp::R_386_TLS_LDM_32:
1048     case elfcpp::R_386_TLS_LDM_PUSH:
1049     case elfcpp::R_386_TLS_LDM_CALL:
1050     case elfcpp::R_386_TLS_LDM_POP:
1051     case elfcpp::R_386_USED_BY_INTEL_200:
1052     default:
1053       unsupported_reloc_global(object, r_type, gsym);
1054       break;
1055     }
1056 }
1057
1058 // Scan relocations for a section.
1059
1060 void
1061 Target_i386::scan_relocs(const General_options& options,
1062                          Symbol_table* symtab,
1063                          Layout* layout,
1064                          Sized_relobj<32, false>* object,
1065                          unsigned int data_shndx,
1066                          unsigned int sh_type,
1067                          const unsigned char* prelocs,
1068                          size_t reloc_count,
1069                          size_t local_symbol_count,
1070                          const unsigned char* plocal_symbols,
1071                          Symbol** global_symbols)
1072 {
1073   if (sh_type == elfcpp::SHT_RELA)
1074     {
1075       fprintf(stderr, _("%s: %s: unsupported RELA reloc section\n"),
1076               program_name, object->name().c_str());
1077       gold_exit(false);
1078     }
1079
1080   gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
1081                     Target_i386::Scan>(
1082     options,
1083     symtab,
1084     layout,
1085     this,
1086     object,
1087     data_shndx,
1088     prelocs,
1089     reloc_count,
1090     local_symbol_count,
1091     plocal_symbols,
1092     global_symbols);
1093 }
1094
1095 // Finalize the sections.
1096
1097 void
1098 Target_i386::do_finalize_sections(Layout* layout)
1099 {
1100   // Fill in some more dynamic tags.
1101   Output_data_dynamic* const odyn = layout->dynamic_data();
1102   if (odyn != NULL)
1103     {
1104       if (this->got_plt_ != NULL)
1105         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1106
1107       if (this->plt_ != NULL)
1108         {
1109           const Output_data* od = this->plt_->rel_plt();
1110           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1111           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1112           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL);
1113         }
1114
1115       if (this->rel_dyn_ != NULL)
1116         {
1117           const Output_data* od = this->rel_dyn_;
1118           odyn->add_section_address(elfcpp::DT_REL, od);
1119           odyn->add_section_size(elfcpp::DT_RELSZ, od);
1120           odyn->add_constant(elfcpp::DT_RELENT,
1121                              elfcpp::Elf_sizes<32>::rel_size);
1122         }
1123
1124       if (!parameters->output_is_shared())
1125         {
1126           // The value of the DT_DEBUG tag is filled in by the dynamic
1127           // linker at run time, and used by the debugger.
1128           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1129         }
1130     }
1131
1132   // Emit any relocs we saved in an attempt to avoid generating COPY
1133   // relocs.
1134   if (this->copy_relocs_ == NULL)
1135     return;
1136   if (this->copy_relocs_->any_to_emit())
1137     {
1138       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1139       this->copy_relocs_->emit(rel_dyn);
1140     }
1141   delete this->copy_relocs_;
1142   this->copy_relocs_ = NULL;
1143 }
1144
1145 // Perform a relocation.
1146
1147 inline bool
1148 Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
1149                                 Target_i386* target,
1150                                 size_t relnum,
1151                                 const elfcpp::Rel<32, false>& rel,
1152                                 unsigned int r_type,
1153                                 const Sized_symbol<32>* gsym,
1154                                 const Symbol_value<32>* psymval,
1155                                 unsigned char* view,
1156                                 elfcpp::Elf_types<32>::Elf_Addr address,
1157                                 off_t view_size)
1158 {
1159   if (this->skip_call_tls_get_addr_)
1160     {
1161       if (r_type != elfcpp::R_386_PLT32
1162           || gsym == NULL
1163           || strcmp(gsym->name(), "___tls_get_addr") != 0)
1164         {
1165           fprintf(stderr, _("%s: %s: missing expected TLS relocation\n"),
1166                   program_name,
1167                   relinfo->location(relnum, rel.get_r_offset()).c_str());
1168           gold_exit(false);
1169         }
1170
1171       this->skip_call_tls_get_addr_ = false;
1172
1173       return false;
1174     }
1175
1176   // Pick the value to use for symbols defined in shared objects.
1177   Symbol_value<32> symval;
1178   if (gsym != NULL && gsym->is_from_dynobj() && gsym->has_plt_offset())
1179     {
1180       symval.set_output_value(target->plt_section()->address()
1181                               + gsym->plt_offset());
1182       psymval = &symval;
1183     }
1184
1185   const Sized_relobj<32, false>* object = relinfo->object;
1186
1187   switch (r_type)
1188     {
1189     case elfcpp::R_386_NONE:
1190     case elfcpp::R_386_GNU_VTINHERIT:
1191     case elfcpp::R_386_GNU_VTENTRY:
1192       break;
1193
1194     case elfcpp::R_386_32:
1195       Relocate_functions<32, false>::rel32(view, object, psymval);
1196       break;
1197
1198     case elfcpp::R_386_PC32:
1199       Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1200       break;
1201
1202     case elfcpp::R_386_16:
1203       Relocate_functions<32, false>::rel16(view, object, psymval);
1204       break;
1205
1206     case elfcpp::R_386_PC16:
1207       Relocate_functions<32, false>::pcrel16(view, object, psymval, address);
1208       break;
1209
1210     case elfcpp::R_386_8:
1211       Relocate_functions<32, false>::rel8(view, object, psymval);
1212       break;
1213
1214     case elfcpp::R_386_PC8:
1215       Relocate_functions<32, false>::pcrel8(view, object, psymval, address);
1216       break;
1217
1218     case elfcpp::R_386_PLT32:
1219       gold_assert(gsym->has_plt_offset()
1220                   || gsym->final_value_is_known());
1221       Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1222       break;
1223
1224     case elfcpp::R_386_GOT32:
1225       // Local GOT offsets not yet supported.
1226       gold_assert(gsym);
1227       gold_assert(gsym->has_got_offset());
1228       Relocate_functions<32, false>::rel32(view, gsym->got_offset());
1229       break;
1230
1231     case elfcpp::R_386_GOTOFF:
1232       {
1233         elfcpp::Elf_types<32>::Elf_Addr value;
1234         value = (psymval->value(object, 0)
1235                  - target->got_section(NULL, NULL)->address());
1236         Relocate_functions<32, false>::rel32(view, value);
1237       }
1238       break;
1239
1240     case elfcpp::R_386_GOTPC:
1241       {
1242         elfcpp::Elf_types<32>::Elf_Addr value;
1243         value = target->got_section(NULL, NULL)->address();
1244         Relocate_functions<32, false>::pcrel32(view, value, address);
1245       }
1246       break;
1247
1248     case elfcpp::R_386_COPY:
1249     case elfcpp::R_386_GLOB_DAT:
1250     case elfcpp::R_386_JUMP_SLOT:
1251     case elfcpp::R_386_RELATIVE:
1252       // These are outstanding tls relocs, which are unexpected when
1253       // linking.
1254     case elfcpp::R_386_TLS_TPOFF:
1255     case elfcpp::R_386_TLS_DTPMOD32:
1256     case elfcpp::R_386_TLS_DTPOFF32:
1257     case elfcpp::R_386_TLS_TPOFF32:
1258     case elfcpp::R_386_TLS_DESC:
1259       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
1260               program_name,
1261               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1262               r_type);
1263       gold_exit(false);
1264       break;
1265
1266       // These are initial tls relocs, which are expected when
1267       // linking.
1268     case elfcpp::R_386_TLS_IE:
1269     case elfcpp::R_386_TLS_GOTIE:
1270     case elfcpp::R_386_TLS_LE:
1271     case elfcpp::R_386_TLS_GD:
1272     case elfcpp::R_386_TLS_LDM:
1273     case elfcpp::R_386_TLS_LDO_32:
1274     case elfcpp::R_386_TLS_IE_32:
1275     case elfcpp::R_386_TLS_LE_32:
1276     case elfcpp::R_386_TLS_GOTDESC:
1277     case elfcpp::R_386_TLS_DESC_CALL:
1278       this->relocate_tls(relinfo, relnum, rel, r_type, gsym, psymval, view,
1279                          address, view_size);
1280       break;
1281
1282     case elfcpp::R_386_32PLT:
1283     case elfcpp::R_386_TLS_GD_32:
1284     case elfcpp::R_386_TLS_GD_PUSH:
1285     case elfcpp::R_386_TLS_GD_CALL:
1286     case elfcpp::R_386_TLS_GD_POP:
1287     case elfcpp::R_386_TLS_LDM_32:
1288     case elfcpp::R_386_TLS_LDM_PUSH:
1289     case elfcpp::R_386_TLS_LDM_CALL:
1290     case elfcpp::R_386_TLS_LDM_POP:
1291     case elfcpp::R_386_USED_BY_INTEL_200:
1292     default:
1293       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1294               program_name,
1295               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1296               r_type);
1297       gold_exit(false);
1298       break;
1299     }
1300
1301   return true;
1302 }
1303
1304 // Perform a TLS relocation.
1305
1306 inline void
1307 Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
1308                                     size_t relnum,
1309                                     const elfcpp::Rel<32, false>& rel,
1310                                     unsigned int r_type,
1311                                     const Sized_symbol<32>* gsym,
1312                                     const Symbol_value<32>* psymval,
1313                                     unsigned char* view,
1314                                     elfcpp::Elf_types<32>::Elf_Addr,
1315                                     off_t view_size)
1316 {
1317   Output_segment* tls_segment = relinfo->layout->tls_segment();
1318   if (tls_segment == NULL)
1319     {
1320       fprintf(stderr, _("%s: %s: TLS reloc but no TLS segment\n"),
1321               program_name,
1322               relinfo->location(relnum, rel.get_r_offset()).c_str());
1323       gold_exit(false);
1324     }
1325
1326   elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(relinfo->object, 0);
1327
1328   const bool is_final = (gsym == NULL
1329                          ? !parameters->output_is_shared()
1330                          : gsym->final_value_is_known());
1331   const tls::Tls_optimization optimized_type
1332       = Target_i386::optimize_tls_reloc(is_final, r_type);
1333   switch (r_type)
1334     {
1335     case elfcpp::R_386_TLS_LE_32:
1336       value = tls_segment->vaddr() + tls_segment->memsz() - value;
1337       Relocate_functions<32, false>::rel32(view, value);
1338       break;
1339
1340     case elfcpp::R_386_TLS_LE:
1341       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1342       Relocate_functions<32, false>::rel32(view, value);
1343       break;
1344
1345     case elfcpp::R_386_TLS_IE:
1346     case elfcpp::R_386_TLS_GOTIE:
1347     case elfcpp::R_386_TLS_IE_32:
1348       if (optimized_type == tls::TLSOPT_TO_LE)
1349         {
1350           Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1351                                               rel, r_type, value, view,
1352                                               view_size);
1353           break;
1354         }
1355       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1356               program_name,
1357               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1358               r_type);
1359       gold_exit(false);
1360       break;
1361
1362     case elfcpp::R_386_TLS_GD:
1363       if (optimized_type == tls::TLSOPT_TO_LE)
1364         {
1365           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1366                              rel, r_type, value, view,
1367                              view_size);
1368           break;
1369         }
1370       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1371               program_name,
1372               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1373               r_type);
1374       gold_exit(false);
1375       break;
1376
1377     case elfcpp::R_386_TLS_LDM:
1378       if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
1379         {
1380           fprintf(stderr,
1381                   _("%s: %s: both SUN and GNU model TLS relocations\n"),
1382                   program_name,
1383                   relinfo->location(relnum, rel.get_r_offset()).c_str());
1384           gold_exit(false);
1385         }
1386       this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
1387       if (optimized_type == tls::TLSOPT_TO_LE)
1388         {
1389           this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
1390                              value, view, view_size);
1391           break;
1392         }
1393       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1394               program_name,
1395               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1396               r_type);
1397       gold_exit(false);
1398       break;
1399
1400     case elfcpp::R_386_TLS_LDO_32:
1401       // This reloc can appear in debugging sections, in which case we
1402       // won't see the TLS_LDM reloc.  The local_dynamic_type field
1403       // tells us this.
1404       if (optimized_type != tls::TLSOPT_TO_LE
1405           || this->local_dynamic_type_ == LOCAL_DYNAMIC_NONE)
1406         value = value - tls_segment->vaddr();
1407       else if (this->local_dynamic_type_ == LOCAL_DYNAMIC_GNU)
1408         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1409       else
1410         value = tls_segment->vaddr() + tls_segment->memsz() - value;
1411       Relocate_functions<32, false>::rel32(view, value);
1412       break;
1413
1414     case elfcpp::R_386_TLS_GOTDESC:
1415     case elfcpp::R_386_TLS_DESC_CALL:
1416       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1417               program_name,
1418               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1419               r_type);
1420       gold_exit(false);
1421       break;
1422     }
1423 }
1424
1425 // Do a relocation in which we convert a TLS Initial-Exec to a
1426 // Local-Exec.
1427
1428 inline void
1429 Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
1430                                     size_t relnum,
1431                                     Output_segment* tls_segment,
1432                                     const elfcpp::Rel<32, false>& rel,
1433                                     unsigned int r_type,
1434                                     elfcpp::Elf_types<32>::Elf_Addr value,
1435                                     unsigned char* view,
1436                                     off_t view_size)
1437 {
1438   // We have to actually change the instructions, which means that we
1439   // need to examine the opcodes to figure out which instruction we
1440   // are looking at.
1441   if (r_type == elfcpp::R_386_TLS_IE)
1442     {
1443       // movl %gs:XX,%eax  ==>  movl $YY,%eax
1444       // movl %gs:XX,%reg  ==>  movl $YY,%reg
1445       // addl %gs:XX,%reg  ==>  addl $YY,%reg
1446       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
1447       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
1448
1449       unsigned char op1 = view[-1];
1450       if (op1 == 0xa1)
1451         {
1452           // movl XX,%eax  ==>  movl $YY,%eax
1453           view[-1] = 0xb8;
1454         }
1455       else
1456         {
1457           tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1458
1459           unsigned char op2 = view[-2];
1460           if (op2 == 0x8b)
1461             {
1462               // movl XX,%reg  ==>  movl $YY,%reg
1463               tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1464                              (op1 & 0xc7) == 0x05);
1465               view[-2] = 0xc7;
1466               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1467             }
1468           else if (op2 == 0x03)
1469             {
1470               // addl XX,%reg  ==>  addl $YY,%reg
1471               tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1472                              (op1 & 0xc7) == 0x05);
1473               view[-2] = 0x81;
1474               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1475             }
1476           else
1477             tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
1478         }
1479     }
1480   else
1481     {
1482       // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1483       // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1484       // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1485       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1486       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
1487
1488       unsigned char op1 = view[-1];
1489       unsigned char op2 = view[-2];
1490       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1491                      (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
1492       if (op2 == 0x8b)
1493         {
1494           // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1495           view[-2] = 0xc7;
1496           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1497         }
1498       else if (op2 == 0x2b)
1499         {
1500           // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1501           view[-2] = 0x81;
1502           view[-1] = 0xe8 | ((op1 >> 3) & 7);
1503         }
1504       else if (op2 == 0x03)
1505         {
1506           // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1507           view[-2] = 0x81;
1508           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1509         }
1510       else
1511         tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
1512     }
1513
1514   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1515   if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
1516     value = - value;
1517
1518   Relocate_functions<32, false>::rel32(view, value);
1519 }
1520
1521 // Do a relocation in which we convert a TLS General-Dynamic to a
1522 // Local-Exec.
1523
1524 inline void
1525 Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
1526                                     size_t relnum,
1527                                     Output_segment* tls_segment,
1528                                     const elfcpp::Rel<32, false>& rel,
1529                                     unsigned int,
1530                                     elfcpp::Elf_types<32>::Elf_Addr value,
1531                                     unsigned char* view,
1532                                     off_t view_size)
1533 {
1534   // leal foo(,%reg,1),%eax; call ___tls_get_addr
1535   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1536   // leal foo(%reg),%eax; call ___tls_get_addr
1537   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1538
1539   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1540   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1541
1542   unsigned char op1 = view[-1];
1543   unsigned char op2 = view[-2];
1544
1545   tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1546                  op2 == 0x8d || op2 == 0x04);
1547   tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1548
1549   int roff = 5;
1550
1551   if (op2 == 0x04)
1552     {
1553       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
1554       tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
1555       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1556                      ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
1557       memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1558     }
1559   else
1560     {
1561       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1562                      (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1563       if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
1564           && view[9] == 0x90)
1565         {
1566           // There is a trailing nop.  Use the size byte subl.
1567           memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1568           roff = 6;
1569         }
1570       else
1571         {
1572           // Use the five byte subl.
1573           memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1574         }
1575     }
1576
1577   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1578   Relocate_functions<32, false>::rel32(view + roff, value);
1579
1580   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1581   // We can skip it.
1582   this->skip_call_tls_get_addr_ = true;
1583 }
1584
1585 // Do a relocation in which we convert a TLS Local-Dynamic to a
1586 // Local-Exec.
1587
1588 inline void
1589 Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
1590                                     size_t relnum,
1591                                     Output_segment*,
1592                                     const elfcpp::Rel<32, false>& rel,
1593                                     unsigned int,
1594                                     elfcpp::Elf_types<32>::Elf_Addr,
1595                                     unsigned char* view,
1596                                     off_t view_size)
1597 {
1598   // leal foo(%reg), %eax; call ___tls_get_addr
1599   // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
1600
1601   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1602   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1603
1604   // FIXME: Does this test really always pass?
1605   tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1606                  view[-2] == 0x8d && view[-1] == 0x83);
1607
1608   tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1609
1610   memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
1611
1612   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1613   // We can skip it.
1614   this->skip_call_tls_get_addr_ = true;
1615 }
1616
1617 // Relocate section data.
1618
1619 void
1620 Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
1621                               unsigned int sh_type,
1622                               const unsigned char* prelocs,
1623                               size_t reloc_count,
1624                               unsigned char* view,
1625                               elfcpp::Elf_types<32>::Elf_Addr address,
1626                               off_t view_size)
1627 {
1628   gold_assert(sh_type == elfcpp::SHT_REL);
1629
1630   gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
1631                          Target_i386::Relocate>(
1632     relinfo,
1633     this,
1634     prelocs,
1635     reloc_count,
1636     view,
1637     address,
1638     view_size);
1639 }
1640
1641 // Return the value to use for a dynamic which requires special
1642 // treatment.  This is how we support equality comparisons of function
1643 // pointers across shared library boundaries, as described in the
1644 // processor specific ABI supplement.
1645
1646 uint64_t
1647 Target_i386::do_dynsym_value(const Symbol* gsym) const
1648 {
1649   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1650   return this->plt_section()->address() + gsym->plt_offset();
1651 }
1652
1653 // Return a string used to fill a code section with nops to take up
1654 // the specified length.
1655
1656 std::string
1657 Target_i386::do_code_fill(off_t length)
1658 {
1659   if (length >= 16)
1660     {
1661       // Build a jmp instruction to skip over the bytes.
1662       unsigned char jmp[5];
1663       jmp[0] = 0xe9;
1664       elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
1665       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1666               + std::string(length - 5, '\0'));
1667     }
1668
1669   // Nop sequences of various lengths.
1670   const char nop1[1] = { 0x90 };                   // nop
1671   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1672   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1673   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1674   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1675                          0x00 };                   // leal 0(%esi,1),%esi
1676   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1677                          0x00, 0x00 };
1678   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1679                          0x00, 0x00, 0x00 };
1680   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1681                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1682   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1683                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1684                          0x00 };
1685   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1686                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1687                            0x00, 0x00 };
1688   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1689                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1690                            0x00, 0x00, 0x00 };
1691   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1692                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1693                            0x00, 0x00, 0x00, 0x00 };
1694   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1695                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1696                            0x27, 0x00, 0x00, 0x00,
1697                            0x00 };
1698   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1699                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1700                            0xbc, 0x27, 0x00, 0x00,
1701                            0x00, 0x00 };
1702   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1703                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1704                            0x90, 0x90, 0x90, 0x90,
1705                            0x90, 0x90, 0x90 };
1706
1707   const char* nops[16] = {
1708     NULL,
1709     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1710     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1711   };
1712
1713   return std::string(nops[length], length);
1714 }
1715
1716 // The selector for i386 object files.
1717
1718 class Target_selector_i386 : public Target_selector
1719 {
1720 public:
1721   Target_selector_i386()
1722     : Target_selector(elfcpp::EM_386, 32, false)
1723   { }
1724
1725   Target*
1726   recognize(int machine, int osabi, int abiversion);
1727
1728  private:
1729   Target_i386* target_;
1730 };
1731
1732 // Recognize an i386 object file when we already know that the machine
1733 // number is EM_386.
1734
1735 Target*
1736 Target_selector_i386::recognize(int, int, int)
1737 {
1738   if (this->target_ == NULL)
1739     this->target_ = new Target_i386();
1740   return this->target_;
1741 }
1742
1743 Target_selector_i386 target_selector_i386;
1744
1745 } // End anonymous namespace.