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               Output_section* output_section,
  74               bool needs_special_offset_handling,
  75               size_t local_symbol_count,
  76               const unsigned char* plocal_symbols);
  77
  78   // Finalize the sections.
  79   void
  80   do_finalize_sections(Layout*);
  81
  82   // Return the value to use for a dynamic which requires special
  83   // treatment.
  84   uint64_t
  85   do_dynsym_value(const Symbol*) const;
  86
  87   // Relocate a section.
  88   void
  89   relocate_section(const Relocate_info<32, false>*,
  90                    unsigned int sh_type,
  91                    const unsigned char* prelocs,
  92                    size_t reloc_count,
  93                    Output_section* output_section,
  94                    bool needs_special_offset_handling,
  95                    unsigned char* view,
  96                    elfcpp::Elf_types<32>::Elf_Addr view_address,
  97                    off_t view_size);
  98
  99   // Return a string used to fill a code section with nops.
 100   std::string
 101   do_code_fill(off_t length);
 102
 103   // Return the size of the GOT section.
 104   off_t
 105   got_size()
 106   {
 107     gold_assert(this->got_ != NULL);
 108     return this->got_->data_size();
 109   }
 110
 111  private:
 112   // The class which scans relocations.
 113   struct Scan
 114   {
 115     inline void
 116     local(const General_options& options, Symbol_table* symtab,
 117           Layout* layout, Target_i386* target,
 118           Sized_relobj<32, false>* object,
 119           unsigned int data_shndx,
 120           const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
 121           const elfcpp::Sym<32, false>& lsym);
 122
 123     inline void
 124     global(const General_options& options, Symbol_table* symtab,
 125            Layout* layout, Target_i386* target,
 126            Sized_relobj<32, false>* object,
 127            unsigned int data_shndx,
 128            const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
 129            Symbol* gsym);
 130
 131     static void
 132     unsupported_reloc_local(Sized_relobj<32, false>*, unsigned int r_type);
 133
 134     static void
 135     unsupported_reloc_global(Sized_relobj<32, false>*, unsigned int r_type,
 136                              Symbol*);
 137   };
 138
 139   // The class which implements relocation.
 140   class Relocate
 141   {
 142    public:
 143     Relocate()
 144       : skip_call_tls_get_addr_(false),
 145         local_dynamic_type_(LOCAL_DYNAMIC_NONE)
 146     { }
 147
 148     ~Relocate()
 149     {
 150       if (this->skip_call_tls_get_addr_)
 151         {
 152           // FIXME: This needs to specify the location somehow.
 153           gold_error(_("missing expected TLS relocation"));
 154         }
 155     }
 156
 157     // Return whether the static relocation needs to be applied.
 158     inline bool
 159     should_apply_static_reloc(const Sized_symbol<32>* gsym,
 160                               bool is_pcrel,
 161                               bool is_32bit);
 162
 163     // Do a relocation.  Return false if the caller should not issue
 164     // any warnings about this relocation.
 165     inline bool
 166     relocate(const Relocate_info<32, false>*, Target_i386*, size_t relnum,
 167              const elfcpp::Rel<32, false>&,
 168              unsigned int r_type, const Sized_symbol<32>*,
 169              const Symbol_value<32>*,
 170              unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
 171              off_t);
 172
 173    private:
 174     // Do a TLS relocation.
 175     inline void
 176     relocate_tls(const Relocate_info<32, false>*, size_t relnum,
 177                  const elfcpp::Rel<32, false>&,
 178                  unsigned int r_type, const Sized_symbol<32>*,
 179                  const Symbol_value<32>*,
 180                  unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, off_t);
 181
 182     // Do a TLS General-Dynamic to Local-Exec transition.
 183     inline void
 184     tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
 185                  Output_segment* tls_segment,
 186                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 187                  elfcpp::Elf_types<32>::Elf_Addr value,
 188                  unsigned char* view,
 189                  off_t view_size);
 190
 191     // Do a TLS Local-Dynamic to Local-Exec transition.
 192     inline void
 193     tls_ld_to_le(const Relocate_info<32, false>*, size_t relnum,
 194                  Output_segment* tls_segment,
 195                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 196                  elfcpp::Elf_types<32>::Elf_Addr value,
 197                  unsigned char* view,
 198                  off_t view_size);
 199
 200     // Do a TLS Initial-Exec to Local-Exec transition.
 201     static inline void
 202     tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum,
 203                  Output_segment* tls_segment,
 204                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 205                  elfcpp::Elf_types<32>::Elf_Addr value,
 206                  unsigned char* view,
 207                  off_t view_size);
 208
 209     // We need to keep track of which type of local dynamic relocation
 210     // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
 211     enum Local_dynamic_type
 212     {
 213       LOCAL_DYNAMIC_NONE,
 214       LOCAL_DYNAMIC_SUN,
 215       LOCAL_DYNAMIC_GNU
 216     };
 217
 218     // This is set if we should skip the next reloc, which should be a
 219     // PLT32 reloc against ___tls_get_addr.
 220     bool skip_call_tls_get_addr_;
 221     // The type of local dynamic relocation we have seen in the section
 222     // being relocated, if any.
 223     Local_dynamic_type local_dynamic_type_;
 224   };
 225
 226   // Adjust TLS relocation type based on the options and whether this
 227   // is a local symbol.
 228   static tls::Tls_optimization
 229   optimize_tls_reloc(bool is_final, int r_type);
 230
 231   // Get the GOT section, creating it if necessary.
 232   Output_data_got<32, false>*
 233   got_section(Symbol_table*, Layout*);
 234
 235   // Get the GOT PLT section.
 236   Output_data_space*
 237   got_plt_section() const
 238   {
 239     gold_assert(this->got_plt_ != NULL);
 240     return this->got_plt_;
 241   }
 242
 243   // Create a PLT entry for a global symbol.
 244   void
 245   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 246
 247   // Get the PLT section.
 248   const Output_data_plt_i386*
 249   plt_section() const
 250   {
 251     gold_assert(this->plt_ != NULL);
 252     return this->plt_;
 253   }
 254
 255   // Get the dynamic reloc section, creating it if necessary.
 256   Reloc_section*
 257   rel_dyn_section(Layout*);
 258
 259   // Copy a relocation against a global symbol.
 260   void
 261   copy_reloc(const General_options*, Symbol_table*, Layout*,
 262              Sized_relobj<32, false>*, unsigned int,
 263              Symbol*, const elfcpp::Rel<32, false>&);
 264
 265   // Information about this specific target which we pass to the
 266   // general Target structure.
 267   static const Target::Target_info i386_info;
 268
 269   // The GOT section.
 270   Output_data_got<32, false>* got_;
 271   // The PLT section.
 272   Output_data_plt_i386* plt_;
 273   // The GOT PLT section.
 274   Output_data_space* got_plt_;
 275   // The dynamic reloc section.
 276   Reloc_section* rel_dyn_;
 277   // Relocs saved to avoid a COPY reloc.
 278   Copy_relocs<32, false>* copy_relocs_;
 279   // Space for variables copied with a COPY reloc.
 280   Output_data_space* dynbss_;
 281 };
 282
 283 const Target::Target_info Target_i386::i386_info =
 284 {
 285   32,                   // size
 286   false,                // is_big_endian
 287   elfcpp::EM_386,       // machine_code
 288   false,                // has_make_symbol
 289   false,                // has_resolve
 290   true,                 // has_code_fill
 291   true,                 // is_default_stack_executable
 292   "/usr/lib/libc.so.1", // dynamic_linker
 293   0x08048000,           // default_text_segment_address
 294   0x1000,               // abi_pagesize
 295   0x1000                // common_pagesize
 296 };
 297
 298 // Get the GOT section, creating it if necessary.
 299
 300 Output_data_got<32, false>*
 301 Target_i386::got_section(Symbol_table* symtab, Layout* layout)
 302 {
 303   if (this->got_ == NULL)
 304     {
 305       gold_assert(symtab != NULL && layout != NULL);
 306
 307       this->got_ = new Output_data_got<32, false>();
 308
 309       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 310                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 311                                       this->got_);
 312
 313       // The old GNU linker creates a .got.plt section.  We just
 314       // create another set of data in the .got section.  Note that we
 315       // always create a PLT if we create a GOT, although the PLT
 316       // might be empty.
 317       this->got_plt_ = new Output_data_space(4);
 318       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 319                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 320                                       this->got_plt_);
 321
 322       // The first three entries are reserved.
 323       this->got_plt_->set_space_size(3 * 4);
 324
 325       // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
 326       symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
 327                                     this->got_plt_,
 328                                     0, 0, elfcpp::STT_OBJECT,
 329                                     elfcpp::STB_LOCAL,
 330                                     elfcpp::STV_HIDDEN, 0,
 331                                     false, false);
 332     }
 333
 334   return this->got_;
 335 }
 336
 337 // Get the dynamic reloc section, creating it if necessary.
 338
 339 Target_i386::Reloc_section*
 340 Target_i386::rel_dyn_section(Layout* layout)
 341 {
 342   if (this->rel_dyn_ == NULL)
 343     {
 344       gold_assert(layout != NULL);
 345       this->rel_dyn_ = new Reloc_section();
 346       layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
 347                                       elfcpp::SHF_ALLOC, this->rel_dyn_);
 348     }
 349   return this->rel_dyn_;
 350 }
 351
 352 // A class to handle the PLT data.
 353
 354 class Output_data_plt_i386 : public Output_section_data
 355 {
 356  public:
 357   typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
 358
 359   Output_data_plt_i386(Layout*, Output_data_space*);
 360
 361   // Add an entry to the PLT.
 362   void
 363   add_entry(Symbol* gsym);
 364
 365   // Return the .rel.plt section data.
 366   const Reloc_section*
 367   rel_plt() const
 368   { return this->rel_; }
 369
 370  protected:
 371   void
 372   do_adjust_output_section(Output_section* os);
 373
 374  private:
 375   // The size of an entry in the PLT.
 376   static const int plt_entry_size = 16;
 377
 378   // The first entry in the PLT for an executable.
 379   static unsigned char exec_first_plt_entry[plt_entry_size];
 380
 381   // The first entry in the PLT for a shared object.
 382   static unsigned char dyn_first_plt_entry[plt_entry_size];
 383
 384   // Other entries in the PLT for an executable.
 385   static unsigned char exec_plt_entry[plt_entry_size];
 386
 387   // Other entries in the PLT for a shared object.
 388   static unsigned char dyn_plt_entry[plt_entry_size];
 389
 390   // Set the final size.
 391   void
 392   do_set_address(uint64_t, off_t)
 393   { this->set_data_size((this->count_ + 1) * plt_entry_size); }
 394
 395   // Write out the PLT data.
 396   void
 397   do_write(Output_file*);
 398
 399   // The reloc section.
 400   Reloc_section* rel_;
 401   // The .got.plt section.
 402   Output_data_space* got_plt_;
 403   // The number of PLT entries.
 404   unsigned int count_;
 405 };
 406
 407 // Create the PLT section.  The ordinary .got section is an argument,
 408 // since we need to refer to the start.  We also create our own .got
 409 // section just for PLT entries.
 410
 411 Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
 412                                            Output_data_space* got_plt)
 413   : Output_section_data(4), got_plt_(got_plt), count_(0)
 414 {
 415   this->rel_ = new Reloc_section();
 416   layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
 417                                   elfcpp::SHF_ALLOC, this->rel_);
 418 }
 419
 420 void
 421 Output_data_plt_i386::do_adjust_output_section(Output_section* os)
 422 {
 423   // UnixWare sets the entsize of .plt to 4, and so does the old GNU
 424   // linker, and so do we.
 425   os->set_entsize(4);
 426 }
 427
 428 // Add an entry to the PLT.
 429
 430 void
 431 Output_data_plt_i386::add_entry(Symbol* gsym)
 432 {
 433   gold_assert(!gsym->has_plt_offset());
 434
 435   // Note that when setting the PLT offset we skip the initial
 436   // reserved PLT entry.
 437   gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
 438
 439   ++this->count_;
 440
 441   off_t got_offset = this->got_plt_->data_size();
 442
 443   // Every PLT entry needs a GOT entry which points back to the PLT
 444   // entry (this will be changed by the dynamic linker, normally
 445   // lazily when the function is called).
 446   this->got_plt_->set_space_size(got_offset + 4);
 447
 448   // Every PLT entry needs a reloc.
 449   gsym->set_needs_dynsym_entry();
 450   this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_,
 451                          got_offset);
 452
 453   // Note that we don't need to save the symbol.  The contents of the
 454   // PLT are independent of which symbols are used.  The symbols only
 455   // appear in the relocations.
 456 }
 457
 458 // The first entry in the PLT for an executable.
 459
 460 unsigned char Output_data_plt_i386::exec_first_plt_entry[plt_entry_size] =
 461 {
 462   0xff, 0x35,   // pushl contents of memory address
 463   0, 0, 0, 0,   // replaced with address of .got + 4
 464   0xff, 0x25,   // jmp indirect
 465   0, 0, 0, 0,   // replaced with address of .got + 8
 466   0, 0, 0, 0    // unused
 467 };
 468
 469 // The first entry in the PLT for a shared object.
 470
 471 unsigned char Output_data_plt_i386::dyn_first_plt_entry[plt_entry_size] =
 472 {
 473   0xff, 0xb3, 4, 0, 0, 0,       // pushl 4(%ebx)
 474   0xff, 0xa3, 8, 0, 0, 0,       // jmp *8(%ebx)
 475   0, 0, 0, 0                    // unused
 476 };
 477
 478 // Subsequent entries in the PLT for an executable.
 479
 480 unsigned char Output_data_plt_i386::exec_plt_entry[plt_entry_size] =
 481 {
 482   0xff, 0x25,   // jmp indirect
 483   0, 0, 0, 0,   // replaced with address of symbol in .got
 484   0x68,         // pushl immediate
 485   0, 0, 0, 0,   // replaced with offset into relocation table
 486   0xe9,         // jmp relative
 487   0, 0, 0, 0    // replaced with offset to start of .plt
 488 };
 489
 490 // Subsequent entries in the PLT for a shared object.
 491
 492 unsigned char Output_data_plt_i386::dyn_plt_entry[plt_entry_size] =
 493 {
 494   0xff, 0xa3,   // jmp *offset(%ebx)
 495   0, 0, 0, 0,   // replaced with offset of symbol in .got
 496   0x68,         // pushl immediate
 497   0, 0, 0, 0,   // replaced with offset into relocation table
 498   0xe9,         // jmp relative
 499   0, 0, 0, 0    // replaced with offset to start of .plt
 500 };
 501
 502 // Write out the PLT.  This uses the hand-coded instructions above,
 503 // and adjusts them as needed.  This is all specified by the i386 ELF
 504 // Processor Supplement.
 505
 506 void
 507 Output_data_plt_i386::do_write(Output_file* of)
 508 {
 509   const off_t offset = this->offset();
 510   const off_t oview_size = this->data_size();
 511   unsigned char* const oview = of->get_output_view(offset, oview_size);
 512
 513   const off_t got_file_offset = this->got_plt_->offset();
 514   const off_t got_size = this->got_plt_->data_size();
 515   unsigned char* const got_view = of->get_output_view(got_file_offset,
 516                                                       got_size);
 517
 518   unsigned char* pov = oview;
 519
 520   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
 521   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 522
 523   if (parameters->output_is_shared())
 524     memcpy(pov, dyn_first_plt_entry, plt_entry_size);
 525   else
 526     {
 527       memcpy(pov, exec_first_plt_entry, plt_entry_size);
 528       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
 529       elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
 530     }
 531   pov += plt_entry_size;
 532
 533   unsigned char* got_pov = got_view;
 534
 535   memset(got_pov, 0, 12);
 536   got_pov += 12;
 537
 538   const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
 539
 540   unsigned int plt_offset = plt_entry_size;
 541   unsigned int plt_rel_offset = 0;
 542   unsigned int got_offset = 12;
 543   const unsigned int count = this->count_;
 544   for (unsigned int i = 0;
 545        i < count;
 546        ++i,
 547          pov += plt_entry_size,
 548          got_pov += 4,
 549          plt_offset += plt_entry_size,
 550          plt_rel_offset += rel_size,
 551          got_offset += 4)
 552     {
 553       // Set and adjust the PLT entry itself.
 554
 555       if (parameters->output_is_shared())
 556         {
 557           memcpy(pov, dyn_plt_entry, plt_entry_size);
 558           elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
 559         }
 560       else
 561         {
 562           memcpy(pov, exec_plt_entry, plt_entry_size);
 563           elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 564                                                       (got_address
 565                                                        + got_offset));
 566         }
 567
 568       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
 569       elfcpp::Swap<32, false>::writeval(pov + 12,
 570                                         - (plt_offset + plt_entry_size));
 571
 572       // Set the entry in the GOT.
 573       elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6);
 574     }
 575
 576   gold_assert(pov - oview == oview_size);
 577   gold_assert(got_pov - got_view == got_size);
 578
 579   of->write_output_view(offset, oview_size, oview);
 580   of->write_output_view(got_file_offset, got_size, got_view);
 581 }
 582
 583 // Create a PLT entry for a global symbol.
 584
 585 void
 586 Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym)
 587 {
 588   if (gsym->has_plt_offset())
 589     return;
 590
 591   if (this->plt_ == NULL)
 592     {
 593       // Create the GOT sections first.
 594       this->got_section(symtab, layout);
 595
 596       this->plt_ = new Output_data_plt_i386(layout, this->got_plt_);
 597       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 598                                       (elfcpp::SHF_ALLOC
 599                                        | elfcpp::SHF_EXECINSTR),
 600                                       this->plt_);
 601     }
 602
 603   this->plt_->add_entry(gsym);
 604 }
 605
 606 // Handle a relocation against a non-function symbol defined in a
 607 // dynamic object.  The traditional way to handle this is to generate
 608 // a COPY relocation to copy the variable at runtime from the shared
 609 // object into the executable's data segment.  However, this is
 610 // undesirable in general, as if the size of the object changes in the
 611 // dynamic object, the executable will no longer work correctly.  If
 612 // this relocation is in a writable section, then we can create a
 613 // dynamic reloc and the dynamic linker will resolve it to the correct
 614 // address at runtime.  However, we do not want do that if the
 615 // relocation is in a read-only section, as it would prevent the
 616 // readonly segment from being shared.  And if we have to eventually
 617 // generate a COPY reloc, then any dynamic relocations will be
 618 // useless.  So this means that if this is a writable section, we need
 619 // to save the relocation until we see whether we have to create a
 620 // COPY relocation for this symbol for any other relocation.
 621
 622 void
 623 Target_i386::copy_reloc(const General_options* options,
 624                         Symbol_table* symtab,
 625                         Layout* layout,
 626                         Sized_relobj<32, false>* object,
 627                         unsigned int data_shndx, Symbol* gsym,
 628                         const elfcpp::Rel<32, false>& rel)
 629 {
 630   Sized_symbol<32>* ssym;
 631   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(32) (gsym
 632                                                         SELECT_SIZE(32));
 633
 634   if (!Copy_relocs<32, false>::need_copy_reloc(options, object,
 635                                                data_shndx, ssym))
 636     {
 637       // So far we do not need a COPY reloc.  Save this relocation.
 638       // If it turns out that we never need a COPY reloc for this
 639       // symbol, then we will emit the relocation.
 640       if (this->copy_relocs_ == NULL)
 641         this->copy_relocs_ = new Copy_relocs<32, false>();
 642       this->copy_relocs_->save(ssym, object, data_shndx, rel);
 643     }
 644   else
 645     {
 646       // Allocate space for this symbol in the .bss section.
 647
 648       elfcpp::Elf_types<32>::Elf_WXword symsize = ssym->symsize();
 649
 650       // There is no defined way to determine the required alignment
 651       // of the symbol.  We pick the alignment based on the size.  We
 652       // set an arbitrary maximum of 256.
 653       unsigned int align;
 654       for (align = 1; align < 512; align <<= 1)
 655         if ((symsize & align) != 0)
 656           break;
 657
 658       if (this->dynbss_ == NULL)
 659         {
 660           this->dynbss_ = new Output_data_space(align);
 661           layout->add_output_section_data(".bss",
 662                                           elfcpp::SHT_NOBITS,
 663                                           (elfcpp::SHF_ALLOC
 664                                            | elfcpp::SHF_WRITE),
 665                                           this->dynbss_);
 666         }
 667
 668       Output_data_space* dynbss = this->dynbss_;
 669
 670       if (align > dynbss->addralign())
 671         dynbss->set_space_alignment(align);
 672
 673       off_t dynbss_size = dynbss->data_size();
 674       dynbss_size = align_address(dynbss_size, align);
 675       off_t offset = dynbss_size;
 676       dynbss->set_space_size(dynbss_size + symsize);
 677
 678       symtab->define_with_copy_reloc(this, ssym, dynbss, offset);
 679
 680       // Add the COPY reloc.
 681       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
 682       rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset);
 683     }
 684 }
 685
 686 // Optimize the TLS relocation type based on what we know about the
 687 // symbol.  IS_FINAL is true if the final address of this symbol is
 688 // known at link time.
 689
 690 tls::Tls_optimization
 691 Target_i386::optimize_tls_reloc(bool is_final, int r_type)
 692 {
 693   // If we are generating a shared library, then we can't do anything
 694   // in the linker.
 695   if (parameters->output_is_shared())
 696     return tls::TLSOPT_NONE;
 697
 698   switch (r_type)
 699     {
 700     case elfcpp::R_386_TLS_GD:
 701     case elfcpp::R_386_TLS_GOTDESC:
 702     case elfcpp::R_386_TLS_DESC_CALL:
 703       // These are General-Dynamic which permits fully general TLS
 704       // access.  Since we know that we are generating an executable,
 705       // we can convert this to Initial-Exec.  If we also know that
 706       // this is a local symbol, we can further switch to Local-Exec.
 707       if (is_final)
 708         return tls::TLSOPT_TO_LE;
 709       return tls::TLSOPT_TO_IE;
 710
 711     case elfcpp::R_386_TLS_LDM:
 712       // This is Local-Dynamic, which refers to a local symbol in the
 713       // dynamic TLS block.  Since we know that we generating an
 714       // executable, we can switch to Local-Exec.
 715       return tls::TLSOPT_TO_LE;
 716
 717     case elfcpp::R_386_TLS_LDO_32:
 718       // Another type of Local-Dynamic relocation.
 719       return tls::TLSOPT_TO_LE;
 720
 721     case elfcpp::R_386_TLS_IE:
 722     case elfcpp::R_386_TLS_GOTIE:
 723     case elfcpp::R_386_TLS_IE_32:
 724       // These are Initial-Exec relocs which get the thread offset
 725       // from the GOT.  If we know that we are linking against the
 726       // local symbol, we can switch to Local-Exec, which links the
 727       // thread offset into the instruction.
 728       if (is_final)
 729         return tls::TLSOPT_TO_LE;
 730       return tls::TLSOPT_NONE;
 731
 732     case elfcpp::R_386_TLS_LE:
 733     case elfcpp::R_386_TLS_LE_32:
 734       // When we already have Local-Exec, there is nothing further we
 735       // can do.
 736       return tls::TLSOPT_NONE;
 737
 738     default:
 739       gold_unreachable();
 740     }
 741 }
 742
 743 // Report an unsupported relocation against a local symbol.
 744
 745 void
 746 Target_i386::Scan::unsupported_reloc_local(Sized_relobj<32, false>* object,
 747                                            unsigned int r_type)
 748 {
 749   gold_error(_("%s: unsupported reloc %u against local symbol"),
 750              object->name().c_str(), r_type);
 751 }
 752
 753 // Scan a relocation for a local symbol.
 754
 755 inline void
 756 Target_i386::Scan::local(const General_options&,
 757                          Symbol_table* symtab,
 758                          Layout* layout,
 759                          Target_i386* target,
 760                          Sized_relobj<32, false>* object,
 761                          unsigned int data_shndx,
 762                          const elfcpp::Rel<32, false>& reloc,
 763                          unsigned int r_type,
 764                          const elfcpp::Sym<32, false>&)
 765 {
 766   switch (r_type)
 767     {
 768     case elfcpp::R_386_NONE:
 769     case elfcpp::R_386_GNU_VTINHERIT:
 770     case elfcpp::R_386_GNU_VTENTRY:
 771       break;
 772
 773     case elfcpp::R_386_32:
 774     case elfcpp::R_386_16:
 775     case elfcpp::R_386_8:
 776       // If building a shared library (or a position-independent
 777       // executable), we need to create a dynamic relocation for
 778       // this location. The relocation applied at link time will
 779       // apply the link-time value, so we flag the location with
 780       // an R_386_RELATIVE relocation so the dynamic loader can
 781       // relocate it easily.
 782       if (parameters->output_is_position_independent())
 783         {
 784           Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 785           if (r_type == elfcpp::R_386_32)
 786             rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE, data_shndx,
 787                                reloc.get_r_offset());
 788           else
 789             {
 790               unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
 791               rel_dyn->add_local(object, r_sym, r_type, data_shndx,
 792                                  reloc.get_r_offset());
 793             }
 794         }
 795       break;
 796
 797     case elfcpp::R_386_PC32:
 798     case elfcpp::R_386_PC16:
 799     case elfcpp::R_386_PC8:
 800       break;
 801
 802     case elfcpp::R_386_PLT32:
 803       // Since we know this is a local symbol, we can handle this as a
 804       // PC32 reloc.
 805       break;
 806
 807     case elfcpp::R_386_GOTOFF:
 808     case elfcpp::R_386_GOTPC:
 809       // We need a GOT section.
 810       target->got_section(symtab, layout);
 811       break;
 812
 813     case elfcpp::R_386_GOT32:
 814       {
 815         // The symbol requires a GOT entry.
 816         Output_data_got<32, false>* got = target->got_section(symtab, layout);
 817         unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
 818         if (got->add_local(object, r_sym))
 819           {
 820             // If we are generating a shared object, we need to add a
 821             // dynamic RELATIVE relocation for this symbol.
 822             if (parameters->output_is_position_independent())
 823               {
 824                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 825                 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE,
 826                                    data_shndx, reloc.get_r_offset());
 827               }
 828           }
 829       }
 830       break;
 831
 832       // These are relocations which should only be seen by the
 833       // dynamic linker, and should never be seen here.
 834     case elfcpp::R_386_COPY:
 835     case elfcpp::R_386_GLOB_DAT:
 836     case elfcpp::R_386_JUMP_SLOT:
 837     case elfcpp::R_386_RELATIVE:
 838     case elfcpp::R_386_TLS_TPOFF:
 839     case elfcpp::R_386_TLS_DTPMOD32:
 840     case elfcpp::R_386_TLS_DTPOFF32:
 841     case elfcpp::R_386_TLS_TPOFF32:
 842     case elfcpp::R_386_TLS_DESC:
 843       gold_error(_("%s: unexpected reloc %u in object file"),
 844                  object->name().c_str(), r_type);
 845       break;
 846
 847       // These are initial TLS relocs, which are expected when
 848       // linking.
 849     case elfcpp::R_386_TLS_GD:            // Global-dynamic
 850     case elfcpp::R_386_TLS_GOTDESC:       // Global-dynamic (from ~oliva url)
 851     case elfcpp::R_386_TLS_DESC_CALL:
 852     case elfcpp::R_386_TLS_LDM:           // Local-dynamic
 853     case elfcpp::R_386_TLS_LDO_32:        // Alternate local-dynamic
 854     case elfcpp::R_386_TLS_IE:            // Initial-exec
 855     case elfcpp::R_386_TLS_IE_32:
 856     case elfcpp::R_386_TLS_GOTIE:
 857     case elfcpp::R_386_TLS_LE:            // Local-exec
 858     case elfcpp::R_386_TLS_LE_32:
 859       {
 860         bool output_is_shared = parameters->output_is_shared();
 861         const tls::Tls_optimization optimized_type
 862             = Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
 863         switch (r_type)
 864           {
 865           case elfcpp::R_386_TLS_GD:          // Global-dynamic
 866           case elfcpp::R_386_TLS_GOTDESC:     // Global-dynamic (from ~oliva)
 867           case elfcpp::R_386_TLS_DESC_CALL:
 868             // FIXME: If not relaxing to LE, we need to generate
 869             // DTPMOD32 and DTPOFF32 relocs.
 870             if (optimized_type != tls::TLSOPT_TO_LE)
 871               unsupported_reloc_local(object, r_type);
 872             break;
 873
 874           case elfcpp::R_386_TLS_LDM:         // Local-dynamic
 875             // FIXME: If not relaxing to LE, we need to generate a
 876             // DTPMOD32 reloc.
 877             if (optimized_type != tls::TLSOPT_TO_LE)
 878               unsupported_reloc_local(object, r_type);
 879             break;
 880
 881           case elfcpp::R_386_TLS_LDO_32:      // Alternate local-dynamic
 882             break;
 883
 884           case elfcpp::R_386_TLS_IE:          // Initial-exec
 885           case elfcpp::R_386_TLS_IE_32:
 886           case elfcpp::R_386_TLS_GOTIE:
 887             // FIXME: If not relaxing to LE, we need to generate a
 888             // TPOFF or TPOFF32 reloc.
 889             if (optimized_type != tls::TLSOPT_TO_LE)
 890               unsupported_reloc_local(object, r_type);
 891             break;
 892
 893           case elfcpp::R_386_TLS_LE:          // Local-exec
 894           case elfcpp::R_386_TLS_LE_32:
 895             // FIXME: If generating a shared object, we need to copy
 896             // this relocation into the object.
 897             gold_assert(!output_is_shared);
 898             break;
 899
 900           default:
 901             gold_unreachable();
 902           }
 903       }
 904       break;
 905
 906     case elfcpp::R_386_32PLT:
 907     case elfcpp::R_386_TLS_GD_32:
 908     case elfcpp::R_386_TLS_GD_PUSH:
 909     case elfcpp::R_386_TLS_GD_CALL:
 910     case elfcpp::R_386_TLS_GD_POP:
 911     case elfcpp::R_386_TLS_LDM_32:
 912     case elfcpp::R_386_TLS_LDM_PUSH:
 913     case elfcpp::R_386_TLS_LDM_CALL:
 914     case elfcpp::R_386_TLS_LDM_POP:
 915     case elfcpp::R_386_USED_BY_INTEL_200:
 916     default:
 917       unsupported_reloc_local(object, r_type);
 918       break;
 919     }
 920 }
 921
 922 // Report an unsupported relocation against a global symbol.
 923
 924 void
 925 Target_i386::Scan::unsupported_reloc_global(Sized_relobj<32, false>* object,
 926                                             unsigned int r_type,
 927                                             Symbol* gsym)
 928 {
 929   gold_error(_("%s: unsupported reloc %u against global symbol %s"),
 930              object->name().c_str(), r_type, gsym->name());
 931 }
 932
 933 // Scan a relocation for a global symbol.
 934
 935 inline void
 936 Target_i386::Scan::global(const General_options& options,
 937                           Symbol_table* symtab,
 938                           Layout* layout,
 939                           Target_i386* target,
 940                           Sized_relobj<32, false>* object,
 941                           unsigned int data_shndx,
 942                           const elfcpp::Rel<32, false>& reloc,
 943                           unsigned int r_type,
 944                           Symbol* gsym)
 945 {
 946   switch (r_type)
 947     {
 948     case elfcpp::R_386_NONE:
 949     case elfcpp::R_386_GNU_VTINHERIT:
 950     case elfcpp::R_386_GNU_VTENTRY:
 951       break;
 952
 953     case elfcpp::R_386_32:
 954     case elfcpp::R_386_PC32:
 955     case elfcpp::R_386_16:
 956     case elfcpp::R_386_PC16:
 957     case elfcpp::R_386_8:
 958     case elfcpp::R_386_PC8:
 959       {
 960         bool is_pcrel = (r_type == elfcpp::R_386_PC32
 961                          || r_type == elfcpp::R_386_PC16
 962                          || r_type == elfcpp::R_386_PC8);
 963
 964         if (gsym->is_from_dynobj()
 965             || (parameters->output_is_shared()
 966                 && gsym->is_preemptible()))
 967           {
 968             // (a) This symbol is defined in a dynamic object.  If it is a
 969             // function, we make a PLT entry.  Otherwise we need to
 970             // either generate a COPY reloc or copy this reloc.
 971             // (b) We are building a shared object and this symbol is
 972             // preemptible. If it is a function, we make a PLT entry.
 973             // Otherwise, we copy the reloc.
 974             if (gsym->type() == elfcpp::STT_FUNC)
 975               {
 976                 target->make_plt_entry(symtab, layout, gsym);
 977
 978                 // If this is not a PC relative reference, then we may
 979                 // be taking the address of the function.  In that case
 980                 // we need to set the entry in the dynamic symbol table
 981                 // to the address of the PLT entry. We will also need to
 982                 // create a dynamic relocation.
 983                 if (!is_pcrel)
 984                   {
 985                     if (gsym->is_from_dynobj())
 986                       gsym->set_needs_dynsym_value();
 987                     if (parameters->output_is_position_independent())
 988                       {
 989                         Reloc_section* rel_dyn =
 990                           target->rel_dyn_section(layout);
 991                         rel_dyn->add_global(gsym, r_type, object, data_shndx,
 992                                             reloc.get_r_offset());
 993                       }
 994                   }
 995               }
 996             else if (parameters->output_is_shared())
 997               {
 998                 // We do not make COPY relocs in shared objects.
 999                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1000                 rel_dyn->add_global(gsym, r_type, object, data_shndx,
1001                                     reloc.get_r_offset());
1002               }
1003             else
1004               target->copy_reloc(&options, symtab, layout, object, data_shndx,
1005                                  gsym, reloc);
1006           }
1007         else if (!is_pcrel && parameters->output_is_position_independent())
1008           {
1009             // This is not a PC-relative reference, so we need to generate
1010             // a dynamic relocation. At this point, we know the symbol
1011             // is not preemptible, so we can use the RELATIVE relocation.
1012             Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1013             if (r_type == elfcpp::R_386_32)
1014               rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE, data_shndx,
1015                                  reloc.get_r_offset());
1016             else
1017               rel_dyn->add_global(gsym, r_type, object, data_shndx,
1018                                   reloc.get_r_offset());
1019           }
1020       }
1021       break;
1022
1023     case elfcpp::R_386_GOT32:
1024       {
1025         // The symbol requires a GOT entry.
1026         Output_data_got<32, false>* got = target->got_section(symtab, layout);
1027         if (got->add_global(gsym))
1028           {
1029             // If this symbol is not fully resolved, we need to add a
1030             // dynamic relocation for it.
1031             if (!gsym->final_value_is_known())
1032               {
1033                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1034                 rel_dyn->add_global(gsym, elfcpp::R_386_GLOB_DAT, got,
1035                                     gsym->got_offset());
1036               }
1037           }
1038       }
1039       break;
1040
1041     case elfcpp::R_386_PLT32:
1042       // If the symbol is fully resolved, this is just a PC32 reloc.
1043       // Otherwise we need a PLT entry.
1044       if (gsym->final_value_is_known())
1045         break;
1046       // If building a shared library, we can also skip the PLT entry
1047       // if the symbol is defined in the output file and is protected
1048       // or hidden.
1049       if (gsym->is_defined()
1050           && !gsym->is_from_dynobj()
1051           && !gsym->is_preemptible())
1052         break;
1053       target->make_plt_entry(symtab, layout, gsym);
1054       break;
1055
1056     case elfcpp::R_386_GOTOFF:
1057     case elfcpp::R_386_GOTPC:
1058       // We need a GOT section.
1059       target->got_section(symtab, layout);
1060       break;
1061
1062       // These are relocations which should only be seen by the
1063       // dynamic linker, and should never be seen here.
1064     case elfcpp::R_386_COPY:
1065     case elfcpp::R_386_GLOB_DAT:
1066     case elfcpp::R_386_JUMP_SLOT:
1067     case elfcpp::R_386_RELATIVE:
1068     case elfcpp::R_386_TLS_TPOFF:
1069     case elfcpp::R_386_TLS_DTPMOD32:
1070     case elfcpp::R_386_TLS_DTPOFF32:
1071     case elfcpp::R_386_TLS_TPOFF32:
1072     case elfcpp::R_386_TLS_DESC:
1073       gold_error(_("%s: unexpected reloc %u in object file"),
1074                  object->name().c_str(), r_type);
1075       break;
1076
1077       // These are initial tls relocs, which are expected when
1078       // linking.
1079     case elfcpp::R_386_TLS_GD:            // Global-dynamic
1080     case elfcpp::R_386_TLS_GOTDESC:       // Global-dynamic (from ~oliva url)
1081     case elfcpp::R_386_TLS_DESC_CALL:
1082     case elfcpp::R_386_TLS_LDM:           // Local-dynamic
1083     case elfcpp::R_386_TLS_LDO_32:        // Alternate local-dynamic
1084     case elfcpp::R_386_TLS_IE:            // Initial-exec
1085     case elfcpp::R_386_TLS_IE_32:
1086     case elfcpp::R_386_TLS_GOTIE:
1087     case elfcpp::R_386_TLS_LE:            // Local-exec
1088     case elfcpp::R_386_TLS_LE_32:
1089       {
1090         const bool is_final = gsym->final_value_is_known();
1091         const tls::Tls_optimization optimized_type
1092             = Target_i386::optimize_tls_reloc(is_final, r_type);
1093         switch (r_type)
1094           {
1095           case elfcpp::R_386_TLS_GD:          // Global-dynamic
1096           case elfcpp::R_386_TLS_GOTDESC:     // Global-dynamic (~oliva url)
1097           case elfcpp::R_386_TLS_DESC_CALL:
1098             // FIXME: If not relaxing to LE, we need to generate
1099             // DTPMOD32 and DTPOFF32 relocs.
1100             if (optimized_type != tls::TLSOPT_TO_LE)
1101               unsupported_reloc_global(object, r_type, gsym);
1102             break;
1103
1104           case elfcpp::R_386_TLS_LDM:         // Local-dynamic
1105             // FIXME: If not relaxing to LE, we need to generate a
1106             // DTPMOD32 reloc.
1107             if (optimized_type != tls::TLSOPT_TO_LE)
1108               unsupported_reloc_global(object, r_type, gsym);
1109             break;
1110
1111           case elfcpp::R_386_TLS_LDO_32:      // Alternate local-dynamic
1112             break;
1113
1114           case elfcpp::R_386_TLS_IE:          // Initial-exec
1115           case elfcpp::R_386_TLS_IE_32:
1116           case elfcpp::R_386_TLS_GOTIE:
1117             // FIXME: If not relaxing to LE, we need to generate a
1118             // TPOFF or TPOFF32 reloc.
1119             if (optimized_type != tls::TLSOPT_TO_LE)
1120               unsupported_reloc_global(object, r_type, gsym);
1121             break;
1122
1123           case elfcpp::R_386_TLS_LE:          // Local-exec
1124           case elfcpp::R_386_TLS_LE_32:
1125             // FIXME: If generating a shared object, we need to copy
1126             // this relocation into the object.
1127             gold_assert(!parameters->output_is_shared());
1128             break;
1129
1130           default:
1131             gold_unreachable();
1132           }
1133       }
1134       break;
1135
1136     case elfcpp::R_386_32PLT:
1137     case elfcpp::R_386_TLS_GD_32:
1138     case elfcpp::R_386_TLS_GD_PUSH:
1139     case elfcpp::R_386_TLS_GD_CALL:
1140     case elfcpp::R_386_TLS_GD_POP:
1141     case elfcpp::R_386_TLS_LDM_32:
1142     case elfcpp::R_386_TLS_LDM_PUSH:
1143     case elfcpp::R_386_TLS_LDM_CALL:
1144     case elfcpp::R_386_TLS_LDM_POP:
1145     case elfcpp::R_386_USED_BY_INTEL_200:
1146     default:
1147       unsupported_reloc_global(object, r_type, gsym);
1148       break;
1149     }
1150 }
1151
1152 // Scan relocations for a section.
1153
1154 void
1155 Target_i386::scan_relocs(const General_options& options,
1156                          Symbol_table* symtab,
1157                          Layout* layout,
1158                          Sized_relobj<32, false>* object,
1159                          unsigned int data_shndx,
1160                          unsigned int sh_type,
1161                          const unsigned char* prelocs,
1162                          size_t reloc_count,
1163                          Output_section* output_section,
1164                          bool needs_special_offset_handling,
1165                          size_t local_symbol_count,
1166                          const unsigned char* plocal_symbols)
1167 {
1168   if (sh_type == elfcpp::SHT_RELA)
1169     {
1170       gold_error(_("%s: unsupported RELA reloc section"),
1171                  object->name().c_str());
1172       return;
1173     }
1174
1175   gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
1176                     Target_i386::Scan>(
1177     options,
1178     symtab,
1179     layout,
1180     this,
1181     object,
1182     data_shndx,
1183     prelocs,
1184     reloc_count,
1185     output_section,
1186     needs_special_offset_handling,
1187     local_symbol_count,
1188     plocal_symbols);
1189 }
1190
1191 // Finalize the sections.
1192
1193 void
1194 Target_i386::do_finalize_sections(Layout* layout)
1195 {
1196   // Fill in some more dynamic tags.
1197   Output_data_dynamic* const odyn = layout->dynamic_data();
1198   if (odyn != NULL)
1199     {
1200       if (this->got_plt_ != NULL)
1201         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1202
1203       if (this->plt_ != NULL)
1204         {
1205           const Output_data* od = this->plt_->rel_plt();
1206           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1207           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1208           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL);
1209         }
1210
1211       if (this->rel_dyn_ != NULL)
1212         {
1213           const Output_data* od = this->rel_dyn_;
1214           odyn->add_section_address(elfcpp::DT_REL, od);
1215           odyn->add_section_size(elfcpp::DT_RELSZ, od);
1216           odyn->add_constant(elfcpp::DT_RELENT,
1217                              elfcpp::Elf_sizes<32>::rel_size);
1218         }
1219
1220       if (!parameters->output_is_shared())
1221         {
1222           // The value of the DT_DEBUG tag is filled in by the dynamic
1223           // linker at run time, and used by the debugger.
1224           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1225         }
1226     }
1227
1228   // Emit any relocs we saved in an attempt to avoid generating COPY
1229   // relocs.
1230   if (this->copy_relocs_ == NULL)
1231     return;
1232   if (this->copy_relocs_->any_to_emit())
1233     {
1234       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1235       this->copy_relocs_->emit(rel_dyn);
1236     }
1237   delete this->copy_relocs_;
1238   this->copy_relocs_ = NULL;
1239 }
1240
1241 // Return whether a direct absolute static relocation needs to be applied.
1242 // In cases where Scan::local() or Scan::global() has created
1243 // a dynamic relocation other than R_386_RELATIVE, the addend
1244 // of the relocation is carried in the data, and we must not
1245 // apply the static relocation.
1246
1247 inline bool
1248 Target_i386::Relocate::should_apply_static_reloc(const Sized_symbol<32>* gsym,
1249                                                  bool is_pcrel,
1250                                                  bool is_32bit)
1251 {
1252   // For local symbols, return FALSE if a non-RELATIVE dynamic
1253   // relocation was created; return TRUE otherwise.
1254   if (gsym == NULL)
1255     return (!parameters->output_is_position_independent() || is_32bit);
1256
1257   // For global symbols, mimic the logic in Scan::global()
1258   // to decide whether a non-RELATIVE dynamic relocation was
1259   // created.
1260   // FIXME: This is ugly. Try to refactor this logic so it can be
1261   // shared by Scan::global() and Relocate::relocate().
1262   if (gsym->is_from_dynobj()
1263       || (parameters->output_is_shared()
1264           && gsym->is_preemptible()))
1265     {
1266       if (gsym->type() == elfcpp::STT_FUNC)
1267         {
1268           if (!is_pcrel && parameters->output_is_position_independent())
1269             return false;
1270         }
1271       else
1272         return false;
1273     }
1274   else if (!is_pcrel && parameters->output_is_position_independent())
1275     return is_32bit;
1276
1277   // For all other cases, return TRUE
1278   return true;
1279 }
1280
1281 // Perform a relocation.
1282
1283 inline bool
1284 Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
1285                                 Target_i386* target,
1286                                 size_t relnum,
1287                                 const elfcpp::Rel<32, false>& rel,
1288                                 unsigned int r_type,
1289                                 const Sized_symbol<32>* gsym,
1290                                 const Symbol_value<32>* psymval,
1291                                 unsigned char* view,
1292                                 elfcpp::Elf_types<32>::Elf_Addr address,
1293                                 off_t view_size)
1294 {
1295   if (this->skip_call_tls_get_addr_)
1296     {
1297       if (r_type != elfcpp::R_386_PLT32
1298           || gsym == NULL
1299           || strcmp(gsym->name(), "___tls_get_addr") != 0)
1300         gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1301                                _("missing expected TLS relocation"));
1302       else
1303         {
1304           this->skip_call_tls_get_addr_ = false;
1305           return false;
1306         }
1307     }
1308
1309   // Pick the value to use for symbols defined in shared objects.
1310   Symbol_value<32> symval;
1311   if (gsym != NULL
1312       && (gsym->is_from_dynobj()
1313           || (parameters->output_is_shared()
1314               && gsym->is_preemptible()))
1315       && gsym->has_plt_offset())
1316     {
1317       symval.set_output_value(target->plt_section()->address()
1318                               + gsym->plt_offset());
1319       psymval = &symval;
1320     }
1321
1322   const Sized_relobj<32, false>* object = relinfo->object;
1323
1324   // Get the GOT offset if needed.
1325   // The GOT pointer points to the end of the GOT section.
1326   // We need to subtract the size of the GOT section to get
1327   // the actual offset to use in the relocation.
1328   bool have_got_offset = false;
1329   unsigned int got_offset = 0;
1330   switch (r_type)
1331     {
1332     case elfcpp::R_386_GOT32:
1333       if (gsym != NULL)
1334         {
1335           gold_assert(gsym->has_got_offset());
1336           got_offset = gsym->got_offset() - target->got_size();
1337         }
1338       else
1339         {
1340           unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1341           got_offset = object->local_got_offset(r_sym) - target->got_size();
1342         }
1343       have_got_offset = true;
1344       break;
1345
1346     default:
1347       break;
1348     }
1349
1350   switch (r_type)
1351     {
1352     case elfcpp::R_386_NONE:
1353     case elfcpp::R_386_GNU_VTINHERIT:
1354     case elfcpp::R_386_GNU_VTENTRY:
1355       break;
1356
1357     case elfcpp::R_386_32:
1358       if (should_apply_static_reloc(gsym, false, true))
1359         Relocate_functions<32, false>::rel32(view, object, psymval);
1360       break;
1361
1362     case elfcpp::R_386_PC32:
1363       if (should_apply_static_reloc(gsym, true, true))
1364         Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1365       break;
1366
1367     case elfcpp::R_386_16:
1368       if (should_apply_static_reloc(gsym, false, false))
1369         Relocate_functions<32, false>::rel16(view, object, psymval);
1370       break;
1371
1372     case elfcpp::R_386_PC16:
1373       if (should_apply_static_reloc(gsym, true, false))
1374         Relocate_functions<32, false>::pcrel16(view, object, psymval, address);
1375       break;
1376
1377     case elfcpp::R_386_8:
1378       if (should_apply_static_reloc(gsym, false, false))
1379         Relocate_functions<32, false>::rel8(view, object, psymval);
1380       break;
1381
1382     case elfcpp::R_386_PC8:
1383       if (should_apply_static_reloc(gsym, true, false))
1384         Relocate_functions<32, false>::pcrel8(view, object, psymval, address);
1385       break;
1386
1387     case elfcpp::R_386_PLT32:
1388       gold_assert(gsym == NULL
1389                   || gsym->has_plt_offset()
1390                   || gsym->final_value_is_known());
1391       Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1392       break;
1393
1394     case elfcpp::R_386_GOT32:
1395       gold_assert(have_got_offset);
1396       Relocate_functions<32, false>::rel32(view, got_offset);
1397       break;
1398
1399     case elfcpp::R_386_GOTOFF:
1400       {
1401         elfcpp::Elf_types<32>::Elf_Addr value;
1402         value = (psymval->value(object, 0)
1403                  - target->got_plt_section()->address());
1404         Relocate_functions<32, false>::rel32(view, value);
1405       }
1406       break;
1407
1408     case elfcpp::R_386_GOTPC:
1409       {
1410         elfcpp::Elf_types<32>::Elf_Addr value;
1411         value = target->got_plt_section()->address();
1412         Relocate_functions<32, false>::pcrel32(view, value, address);
1413       }
1414       break;
1415
1416     case elfcpp::R_386_COPY:
1417     case elfcpp::R_386_GLOB_DAT:
1418     case elfcpp::R_386_JUMP_SLOT:
1419     case elfcpp::R_386_RELATIVE:
1420       // These are outstanding tls relocs, which are unexpected when
1421       // linking.
1422     case elfcpp::R_386_TLS_TPOFF:
1423     case elfcpp::R_386_TLS_DTPMOD32:
1424     case elfcpp::R_386_TLS_DTPOFF32:
1425     case elfcpp::R_386_TLS_TPOFF32:
1426     case elfcpp::R_386_TLS_DESC:
1427       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1428                              _("unexpected reloc %u in object file"),
1429                              r_type);
1430       break;
1431
1432       // These are initial tls relocs, which are expected when
1433       // linking.
1434     case elfcpp::R_386_TLS_GD:             // Global-dynamic
1435     case elfcpp::R_386_TLS_GOTDESC:        // Global-dynamic (from ~oliva url)
1436     case elfcpp::R_386_TLS_DESC_CALL:
1437     case elfcpp::R_386_TLS_LDM:            // Local-dynamic
1438     case elfcpp::R_386_TLS_LDO_32:         // Alternate local-dynamic
1439     case elfcpp::R_386_TLS_IE:             // Initial-exec
1440     case elfcpp::R_386_TLS_IE_32:
1441     case elfcpp::R_386_TLS_GOTIE:
1442     case elfcpp::R_386_TLS_LE:             // Local-exec
1443     case elfcpp::R_386_TLS_LE_32:
1444       this->relocate_tls(relinfo, relnum, rel, r_type, gsym, psymval, view,
1445                          address, view_size);
1446       break;
1447
1448     case elfcpp::R_386_32PLT:
1449     case elfcpp::R_386_TLS_GD_32:
1450     case elfcpp::R_386_TLS_GD_PUSH:
1451     case elfcpp::R_386_TLS_GD_CALL:
1452     case elfcpp::R_386_TLS_GD_POP:
1453     case elfcpp::R_386_TLS_LDM_32:
1454     case elfcpp::R_386_TLS_LDM_PUSH:
1455     case elfcpp::R_386_TLS_LDM_CALL:
1456     case elfcpp::R_386_TLS_LDM_POP:
1457     case elfcpp::R_386_USED_BY_INTEL_200:
1458     default:
1459       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1460                              _("unsupported reloc %u"),
1461                              r_type);
1462       break;
1463     }
1464
1465   return true;
1466 }
1467
1468 // Perform a TLS relocation.
1469
1470 inline void
1471 Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
1472                                     size_t relnum,
1473                                     const elfcpp::Rel<32, false>& rel,
1474                                     unsigned int r_type,
1475                                     const Sized_symbol<32>* gsym,
1476                                     const Symbol_value<32>* psymval,
1477                                     unsigned char* view,
1478                                     elfcpp::Elf_types<32>::Elf_Addr,
1479                                     off_t view_size)
1480 {
1481   Output_segment* tls_segment = relinfo->layout->tls_segment();
1482   if (tls_segment == NULL)
1483     {
1484       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1485                              _("TLS reloc but no TLS segment"));
1486       return;
1487     }
1488
1489   elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(relinfo->object, 0);
1490
1491   const bool is_final = (gsym == NULL
1492                          ? !parameters->output_is_position_independent()
1493                          : gsym->final_value_is_known());
1494   const tls::Tls_optimization optimized_type
1495       = Target_i386::optimize_tls_reloc(is_final, r_type);
1496   switch (r_type)
1497     {
1498     case elfcpp::R_386_TLS_GD:           // Global-dynamic
1499       if (optimized_type == tls::TLSOPT_TO_LE)
1500         {
1501           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1502                              rel, r_type, value, view,
1503                              view_size);
1504           break;
1505         }
1506       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1507                              _("unsupported reloc %u"),
1508                              r_type);
1509       break;
1510
1511     case elfcpp::R_386_TLS_GOTDESC:      // Global-dynamic (from ~oliva url)
1512     case elfcpp::R_386_TLS_DESC_CALL:
1513       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1514                              _("unsupported reloc %u"),
1515                              r_type);
1516       break;
1517
1518     case elfcpp::R_386_TLS_LDM:          // Local-dynamic
1519       if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
1520         {
1521           gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1522                                  _("both SUN and GNU model "
1523                                    "TLS relocations"));
1524           break;
1525         }
1526       this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
1527       if (optimized_type == tls::TLSOPT_TO_LE)
1528         {
1529           this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
1530                              value, view, view_size);
1531           break;
1532         }
1533       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1534                              _("unsupported reloc %u"),
1535                              r_type);
1536       break;
1537
1538     case elfcpp::R_386_TLS_LDO_32:       // Alternate local-dynamic
1539       // This reloc can appear in debugging sections, in which case we
1540       // won't see the TLS_LDM reloc.  The local_dynamic_type field
1541       // tells us this.
1542       if (optimized_type != tls::TLSOPT_TO_LE
1543           || this->local_dynamic_type_ == LOCAL_DYNAMIC_NONE)
1544         value = value - tls_segment->vaddr();
1545       else if (this->local_dynamic_type_ == LOCAL_DYNAMIC_GNU)
1546         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1547       else
1548         value = tls_segment->vaddr() + tls_segment->memsz() - value;
1549       Relocate_functions<32, false>::rel32(view, value);
1550       break;
1551
1552     case elfcpp::R_386_TLS_IE:           // Initial-exec
1553     case elfcpp::R_386_TLS_GOTIE:
1554     case elfcpp::R_386_TLS_IE_32:
1555       if (optimized_type == tls::TLSOPT_TO_LE)
1556         {
1557           Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1558                                               rel, r_type, value, view,
1559                                               view_size);
1560           break;
1561         }
1562       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1563                              _("unsupported reloc %u"),
1564                              r_type);
1565       break;
1566
1567     case elfcpp::R_386_TLS_LE:           // Local-exec
1568       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1569       Relocate_functions<32, false>::rel32(view, value);
1570       break;
1571
1572     case elfcpp::R_386_TLS_LE_32:
1573       value = tls_segment->vaddr() + tls_segment->memsz() - value;
1574       Relocate_functions<32, false>::rel32(view, value);
1575       break;
1576     }
1577 }
1578
1579 // Do a relocation in which we convert a TLS General-Dynamic to a
1580 // Local-Exec.
1581
1582 inline void
1583 Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
1584                                     size_t relnum,
1585                                     Output_segment* tls_segment,
1586                                     const elfcpp::Rel<32, false>& rel,
1587                                     unsigned int,
1588                                     elfcpp::Elf_types<32>::Elf_Addr value,
1589                                     unsigned char* view,
1590                                     off_t view_size)
1591 {
1592   // leal foo(,%reg,1),%eax; call ___tls_get_addr
1593   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1594   // leal foo(%reg),%eax; call ___tls_get_addr
1595   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1596
1597   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1598   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1599
1600   unsigned char op1 = view[-1];
1601   unsigned char op2 = view[-2];
1602
1603   tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1604                  op2 == 0x8d || op2 == 0x04);
1605   tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1606
1607   int roff = 5;
1608
1609   if (op2 == 0x04)
1610     {
1611       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
1612       tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
1613       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1614                      ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
1615       memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1616     }
1617   else
1618     {
1619       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1620                      (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1621       if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
1622           && view[9] == 0x90)
1623         {
1624           // There is a trailing nop.  Use the size byte subl.
1625           memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1626           roff = 6;
1627         }
1628       else
1629         {
1630           // Use the five byte subl.
1631           memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1632         }
1633     }
1634
1635   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1636   Relocate_functions<32, false>::rel32(view + roff, value);
1637
1638   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1639   // We can skip it.
1640   this->skip_call_tls_get_addr_ = true;
1641 }
1642
1643 // Do a relocation in which we convert a TLS Local-Dynamic to a
1644 // Local-Exec.
1645
1646 inline void
1647 Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
1648                                     size_t relnum,
1649                                     Output_segment*,
1650                                     const elfcpp::Rel<32, false>& rel,
1651                                     unsigned int,
1652                                     elfcpp::Elf_types<32>::Elf_Addr,
1653                                     unsigned char* view,
1654                                     off_t view_size)
1655 {
1656   // leal foo(%reg), %eax; call ___tls_get_addr
1657   // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
1658
1659   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1660   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1661
1662   // FIXME: Does this test really always pass?
1663   tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1664                  view[-2] == 0x8d && view[-1] == 0x83);
1665
1666   tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1667
1668   memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
1669
1670   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1671   // We can skip it.
1672   this->skip_call_tls_get_addr_ = true;
1673 }
1674
1675 // Do a relocation in which we convert a TLS Initial-Exec to a
1676 // Local-Exec.
1677
1678 inline void
1679 Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
1680                                     size_t relnum,
1681                                     Output_segment* tls_segment,
1682                                     const elfcpp::Rel<32, false>& rel,
1683                                     unsigned int r_type,
1684                                     elfcpp::Elf_types<32>::Elf_Addr value,
1685                                     unsigned char* view,
1686                                     off_t view_size)
1687 {
1688   // We have to actually change the instructions, which means that we
1689   // need to examine the opcodes to figure out which instruction we
1690   // are looking at.
1691   if (r_type == elfcpp::R_386_TLS_IE)
1692     {
1693       // movl %gs:XX,%eax  ==>  movl $YY,%eax
1694       // movl %gs:XX,%reg  ==>  movl $YY,%reg
1695       // addl %gs:XX,%reg  ==>  addl $YY,%reg
1696       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
1697       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
1698
1699       unsigned char op1 = view[-1];
1700       if (op1 == 0xa1)
1701         {
1702           // movl XX,%eax  ==>  movl $YY,%eax
1703           view[-1] = 0xb8;
1704         }
1705       else
1706         {
1707           tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1708
1709           unsigned char op2 = view[-2];
1710           if (op2 == 0x8b)
1711             {
1712               // movl XX,%reg  ==>  movl $YY,%reg
1713               tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1714                              (op1 & 0xc7) == 0x05);
1715               view[-2] = 0xc7;
1716               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1717             }
1718           else if (op2 == 0x03)
1719             {
1720               // addl XX,%reg  ==>  addl $YY,%reg
1721               tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1722                              (op1 & 0xc7) == 0x05);
1723               view[-2] = 0x81;
1724               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1725             }
1726           else
1727             tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
1728         }
1729     }
1730   else
1731     {
1732       // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1733       // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1734       // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1735       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1736       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
1737
1738       unsigned char op1 = view[-1];
1739       unsigned char op2 = view[-2];
1740       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1741                      (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
1742       if (op2 == 0x8b)
1743         {
1744           // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1745           view[-2] = 0xc7;
1746           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1747         }
1748       else if (op2 == 0x2b)
1749         {
1750           // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1751           view[-2] = 0x81;
1752           view[-1] = 0xe8 | ((op1 >> 3) & 7);
1753         }
1754       else if (op2 == 0x03)
1755         {
1756           // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1757           view[-2] = 0x81;
1758           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1759         }
1760       else
1761         tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
1762     }
1763
1764   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1765   if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
1766     value = - value;
1767
1768   Relocate_functions<32, false>::rel32(view, value);
1769 }
1770
1771 // Relocate section data.
1772
1773 void
1774 Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
1775                               unsigned int sh_type,
1776                               const unsigned char* prelocs,
1777                               size_t reloc_count,
1778                               Output_section* output_section,
1779                               bool needs_special_offset_handling,
1780                               unsigned char* view,
1781                               elfcpp::Elf_types<32>::Elf_Addr address,
1782                               off_t view_size)
1783 {
1784   gold_assert(sh_type == elfcpp::SHT_REL);
1785
1786   gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
1787                          Target_i386::Relocate>(
1788     relinfo,
1789     this,
1790     prelocs,
1791     reloc_count,
1792     output_section,
1793     needs_special_offset_handling,
1794     view,
1795     address,
1796     view_size);
1797 }
1798
1799 // Return the value to use for a dynamic which requires special
1800 // treatment.  This is how we support equality comparisons of function
1801 // pointers across shared library boundaries, as described in the
1802 // processor specific ABI supplement.
1803
1804 uint64_t
1805 Target_i386::do_dynsym_value(const Symbol* gsym) const
1806 {
1807   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1808   return this->plt_section()->address() + gsym->plt_offset();
1809 }
1810
1811 // Return a string used to fill a code section with nops to take up
1812 // the specified length.
1813
1814 std::string
1815 Target_i386::do_code_fill(off_t length)
1816 {
1817   if (length >= 16)
1818     {
1819       // Build a jmp instruction to skip over the bytes.
1820       unsigned char jmp[5];
1821       jmp[0] = 0xe9;
1822       elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
1823       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1824               + std::string(length - 5, '\0'));
1825     }
1826
1827   // Nop sequences of various lengths.
1828   const char nop1[1] = { 0x90 };                   // nop
1829   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1830   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1831   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1832   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1833                          0x00 };                   // leal 0(%esi,1),%esi
1834   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1835                          0x00, 0x00 };
1836   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1837                          0x00, 0x00, 0x00 };
1838   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1839                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1840   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1841                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1842                          0x00 };
1843   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1844                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1845                            0x00, 0x00 };
1846   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1847                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1848                            0x00, 0x00, 0x00 };
1849   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1850                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1851                            0x00, 0x00, 0x00, 0x00 };
1852   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1853                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1854                            0x27, 0x00, 0x00, 0x00,
1855                            0x00 };
1856   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1857                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1858                            0xbc, 0x27, 0x00, 0x00,
1859                            0x00, 0x00 };
1860   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1861                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1862                            0x90, 0x90, 0x90, 0x90,
1863                            0x90, 0x90, 0x90 };
1864
1865   const char* nops[16] = {
1866     NULL,
1867     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1868     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1869   };
1870
1871   return std::string(nops[length], length);
1872 }
1873
1874 // The selector for i386 object files.
1875
1876 class Target_selector_i386 : public Target_selector
1877 {
1878 public:
1879   Target_selector_i386()
1880     : Target_selector(elfcpp::EM_386, 32, false)
1881   { }
1882
1883   Target*
1884   recognize(int machine, int osabi, int abiversion);
1885
1886  private:
1887   Target_i386* target_;
1888 };
1889
1890 // Recognize an i386 object file when we already know that the machine
1891 // number is EM_386.
1892
1893 Target*
1894 Target_selector_i386::recognize(int, int, int)
1895 {
1896   if (this->target_ == NULL)
1897     this->target_ = new Target_i386();
1898   return this->target_;
1899 }
1900
1901 Target_selector_i386 target_selector_i386;
1902
1903 } // End anonymous namespace.