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_absolute_ref,
 161                               bool is_function_call,
 162                               bool is_32bit);
 163
 164     // Do a relocation.  Return false if the caller should not issue
 165     // any warnings about this relocation.
 166     inline bool
 167     relocate(const Relocate_info<32, false>*, Target_i386*, size_t relnum,
 168              const elfcpp::Rel<32, false>&,
 169              unsigned int r_type, const Sized_symbol<32>*,
 170              const Symbol_value<32>*,
 171              unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
 172              off_t);
 173
 174    private:
 175     // Do a TLS relocation.
 176     inline void
 177     relocate_tls(const Relocate_info<32, false>*, size_t relnum,
 178                  const elfcpp::Rel<32, false>&,
 179                  unsigned int r_type, const Sized_symbol<32>*,
 180                  const Symbol_value<32>*,
 181                  unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, off_t);
 182
 183     // Do a TLS General-Dynamic to Local-Exec transition.
 184     inline void
 185     tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
 186                  Output_segment* tls_segment,
 187                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 188                  elfcpp::Elf_types<32>::Elf_Addr value,
 189                  unsigned char* view,
 190                  off_t view_size);
 191
 192     // Do a TLS Local-Dynamic to Local-Exec transition.
 193     inline void
 194     tls_ld_to_le(const Relocate_info<32, false>*, size_t relnum,
 195                  Output_segment* tls_segment,
 196                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 197                  elfcpp::Elf_types<32>::Elf_Addr value,
 198                  unsigned char* view,
 199                  off_t view_size);
 200
 201     // Do a TLS Initial-Exec to Local-Exec transition.
 202     static inline void
 203     tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum,
 204                  Output_segment* tls_segment,
 205                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 206                  elfcpp::Elf_types<32>::Elf_Addr value,
 207                  unsigned char* view,
 208                  off_t view_size);
 209
 210     // We need to keep track of which type of local dynamic relocation
 211     // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
 212     enum Local_dynamic_type
 213     {
 214       LOCAL_DYNAMIC_NONE,
 215       LOCAL_DYNAMIC_SUN,
 216       LOCAL_DYNAMIC_GNU
 217     };
 218
 219     // This is set if we should skip the next reloc, which should be a
 220     // PLT32 reloc against ___tls_get_addr.
 221     bool skip_call_tls_get_addr_;
 222     // The type of local dynamic relocation we have seen in the section
 223     // being relocated, if any.
 224     Local_dynamic_type local_dynamic_type_;
 225   };
 226
 227   // Adjust TLS relocation type based on the options and whether this
 228   // is a local symbol.
 229   static tls::Tls_optimization
 230   optimize_tls_reloc(bool is_final, int r_type);
 231
 232   // Get the GOT section, creating it if necessary.
 233   Output_data_got<32, false>*
 234   got_section(Symbol_table*, Layout*);
 235
 236   // Get the GOT PLT section.
 237   Output_data_space*
 238   got_plt_section() const
 239   {
 240     gold_assert(this->got_plt_ != NULL);
 241     return this->got_plt_;
 242   }
 243
 244   // Create a PLT entry for a global symbol.
 245   void
 246   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 247
 248   // Get the PLT section.
 249   const Output_data_plt_i386*
 250   plt_section() const
 251   {
 252     gold_assert(this->plt_ != NULL);
 253     return this->plt_;
 254   }
 255
 256   // Get the dynamic reloc section, creating it if necessary.
 257   Reloc_section*
 258   rel_dyn_section(Layout*);
 259
 260   // Return true if the symbol may need a COPY relocation.
 261   // References from an executable object to non-function symbols
 262   // defined in a dynamic object may need a COPY relocation.
 263   bool
 264   may_need_copy_reloc(Symbol* gsym)
 265   {
 266     return (!parameters->output_is_shared()
 267             && gsym->is_from_dynobj()
 268             && gsym->type() != elfcpp::STT_FUNC);
 269   }
 270
 271   // Copy a relocation against a global symbol.
 272   void
 273   copy_reloc(const General_options*, Symbol_table*, Layout*,
 274              Sized_relobj<32, false>*, unsigned int,
 275              Symbol*, const elfcpp::Rel<32, false>&);
 276
 277   // Information about this specific target which we pass to the
 278   // general Target structure.
 279   static const Target::Target_info i386_info;
 280
 281   // The GOT section.
 282   Output_data_got<32, false>* got_;
 283   // The PLT section.
 284   Output_data_plt_i386* plt_;
 285   // The GOT PLT section.
 286   Output_data_space* got_plt_;
 287   // The dynamic reloc section.
 288   Reloc_section* rel_dyn_;
 289   // Relocs saved to avoid a COPY reloc.
 290   Copy_relocs<32, false>* copy_relocs_;
 291   // Space for variables copied with a COPY reloc.
 292   Output_data_space* dynbss_;
 293 };
 294
 295 const Target::Target_info Target_i386::i386_info =
 296 {
 297   32,                   // size
 298   false,                // is_big_endian
 299   elfcpp::EM_386,       // machine_code
 300   false,                // has_make_symbol
 301   false,                // has_resolve
 302   true,                 // has_code_fill
 303   true,                 // is_default_stack_executable
 304   "/usr/lib/libc.so.1", // dynamic_linker
 305   0x08048000,           // default_text_segment_address
 306   0x1000,               // abi_pagesize
 307   0x1000                // common_pagesize
 308 };
 309
 310 // Get the GOT section, creating it if necessary.
 311
 312 Output_data_got<32, false>*
 313 Target_i386::got_section(Symbol_table* symtab, Layout* layout)
 314 {
 315   if (this->got_ == NULL)
 316     {
 317       gold_assert(symtab != NULL && layout != NULL);
 318
 319       this->got_ = new Output_data_got<32, false>();
 320
 321       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 322                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 323                                       this->got_);
 324
 325       // The old GNU linker creates a .got.plt section.  We just
 326       // create another set of data in the .got section.  Note that we
 327       // always create a PLT if we create a GOT, although the PLT
 328       // might be empty.
 329       this->got_plt_ = new Output_data_space(4);
 330       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 331                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 332                                       this->got_plt_);
 333
 334       // The first three entries are reserved.
 335       this->got_plt_->set_space_size(3 * 4);
 336
 337       // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
 338       symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
 339                                     this->got_plt_,
 340                                     0, 0, elfcpp::STT_OBJECT,
 341                                     elfcpp::STB_LOCAL,
 342                                     elfcpp::STV_HIDDEN, 0,
 343                                     false, false);
 344     }
 345
 346   return this->got_;
 347 }
 348
 349 // Get the dynamic reloc section, creating it if necessary.
 350
 351 Target_i386::Reloc_section*
 352 Target_i386::rel_dyn_section(Layout* layout)
 353 {
 354   if (this->rel_dyn_ == NULL)
 355     {
 356       gold_assert(layout != NULL);
 357       this->rel_dyn_ = new Reloc_section();
 358       layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
 359                                       elfcpp::SHF_ALLOC, this->rel_dyn_);
 360     }
 361   return this->rel_dyn_;
 362 }
 363
 364 // A class to handle the PLT data.
 365
 366 class Output_data_plt_i386 : public Output_section_data
 367 {
 368  public:
 369   typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
 370
 371   Output_data_plt_i386(Layout*, Output_data_space*);
 372
 373   // Add an entry to the PLT.
 374   void
 375   add_entry(Symbol* gsym);
 376
 377   // Return the .rel.plt section data.
 378   const Reloc_section*
 379   rel_plt() const
 380   { return this->rel_; }
 381
 382  protected:
 383   void
 384   do_adjust_output_section(Output_section* os);
 385
 386  private:
 387   // The size of an entry in the PLT.
 388   static const int plt_entry_size = 16;
 389
 390   // The first entry in the PLT for an executable.
 391   static unsigned char exec_first_plt_entry[plt_entry_size];
 392
 393   // The first entry in the PLT for a shared object.
 394   static unsigned char dyn_first_plt_entry[plt_entry_size];
 395
 396   // Other entries in the PLT for an executable.
 397   static unsigned char exec_plt_entry[plt_entry_size];
 398
 399   // Other entries in the PLT for a shared object.
 400   static unsigned char dyn_plt_entry[plt_entry_size];
 401
 402   // Set the final size.
 403   void
 404   do_set_address(uint64_t, off_t)
 405   { this->set_data_size((this->count_ + 1) * plt_entry_size); }
 406
 407   // Write out the PLT data.
 408   void
 409   do_write(Output_file*);
 410
 411   // The reloc section.
 412   Reloc_section* rel_;
 413   // The .got.plt section.
 414   Output_data_space* got_plt_;
 415   // The number of PLT entries.
 416   unsigned int count_;
 417 };
 418
 419 // Create the PLT section.  The ordinary .got section is an argument,
 420 // since we need to refer to the start.  We also create our own .got
 421 // section just for PLT entries.
 422
 423 Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
 424                                            Output_data_space* got_plt)
 425   : Output_section_data(4), got_plt_(got_plt), count_(0)
 426 {
 427   this->rel_ = new Reloc_section();
 428   layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
 429                                   elfcpp::SHF_ALLOC, this->rel_);
 430 }
 431
 432 void
 433 Output_data_plt_i386::do_adjust_output_section(Output_section* os)
 434 {
 435   // UnixWare sets the entsize of .plt to 4, and so does the old GNU
 436   // linker, and so do we.
 437   os->set_entsize(4);
 438 }
 439
 440 // Add an entry to the PLT.
 441
 442 void
 443 Output_data_plt_i386::add_entry(Symbol* gsym)
 444 {
 445   gold_assert(!gsym->has_plt_offset());
 446
 447   // Note that when setting the PLT offset we skip the initial
 448   // reserved PLT entry.
 449   gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
 450
 451   ++this->count_;
 452
 453   off_t got_offset = this->got_plt_->data_size();
 454
 455   // Every PLT entry needs a GOT entry which points back to the PLT
 456   // entry (this will be changed by the dynamic linker, normally
 457   // lazily when the function is called).
 458   this->got_plt_->set_space_size(got_offset + 4);
 459
 460   // Every PLT entry needs a reloc.
 461   gsym->set_needs_dynsym_entry();
 462   this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_,
 463                          got_offset);
 464
 465   // Note that we don't need to save the symbol.  The contents of the
 466   // PLT are independent of which symbols are used.  The symbols only
 467   // appear in the relocations.
 468 }
 469
 470 // The first entry in the PLT for an executable.
 471
 472 unsigned char Output_data_plt_i386::exec_first_plt_entry[plt_entry_size] =
 473 {
 474   0xff, 0x35,   // pushl contents of memory address
 475   0, 0, 0, 0,   // replaced with address of .got + 4
 476   0xff, 0x25,   // jmp indirect
 477   0, 0, 0, 0,   // replaced with address of .got + 8
 478   0, 0, 0, 0    // unused
 479 };
 480
 481 // The first entry in the PLT for a shared object.
 482
 483 unsigned char Output_data_plt_i386::dyn_first_plt_entry[plt_entry_size] =
 484 {
 485   0xff, 0xb3, 4, 0, 0, 0,       // pushl 4(%ebx)
 486   0xff, 0xa3, 8, 0, 0, 0,       // jmp *8(%ebx)
 487   0, 0, 0, 0                    // unused
 488 };
 489
 490 // Subsequent entries in the PLT for an executable.
 491
 492 unsigned char Output_data_plt_i386::exec_plt_entry[plt_entry_size] =
 493 {
 494   0xff, 0x25,   // jmp indirect
 495   0, 0, 0, 0,   // replaced with address 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 // Subsequent entries in the PLT for a shared object.
 503
 504 unsigned char Output_data_plt_i386::dyn_plt_entry[plt_entry_size] =
 505 {
 506   0xff, 0xa3,   // jmp *offset(%ebx)
 507   0, 0, 0, 0,   // replaced with offset of symbol in .got
 508   0x68,         // pushl immediate
 509   0, 0, 0, 0,   // replaced with offset into relocation table
 510   0xe9,         // jmp relative
 511   0, 0, 0, 0    // replaced with offset to start of .plt
 512 };
 513
 514 // Write out the PLT.  This uses the hand-coded instructions above,
 515 // and adjusts them as needed.  This is all specified by the i386 ELF
 516 // Processor Supplement.
 517
 518 void
 519 Output_data_plt_i386::do_write(Output_file* of)
 520 {
 521   const off_t offset = this->offset();
 522   const off_t oview_size = this->data_size();
 523   unsigned char* const oview = of->get_output_view(offset, oview_size);
 524
 525   const off_t got_file_offset = this->got_plt_->offset();
 526   const off_t got_size = this->got_plt_->data_size();
 527   unsigned char* const got_view = of->get_output_view(got_file_offset,
 528                                                       got_size);
 529
 530   unsigned char* pov = oview;
 531
 532   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
 533   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 534
 535   if (parameters->output_is_shared())
 536     memcpy(pov, dyn_first_plt_entry, plt_entry_size);
 537   else
 538     {
 539       memcpy(pov, exec_first_plt_entry, plt_entry_size);
 540       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
 541       elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
 542     }
 543   pov += plt_entry_size;
 544
 545   unsigned char* got_pov = got_view;
 546
 547   memset(got_pov, 0, 12);
 548   got_pov += 12;
 549
 550   const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
 551
 552   unsigned int plt_offset = plt_entry_size;
 553   unsigned int plt_rel_offset = 0;
 554   unsigned int got_offset = 12;
 555   const unsigned int count = this->count_;
 556   for (unsigned int i = 0;
 557        i < count;
 558        ++i,
 559          pov += plt_entry_size,
 560          got_pov += 4,
 561          plt_offset += plt_entry_size,
 562          plt_rel_offset += rel_size,
 563          got_offset += 4)
 564     {
 565       // Set and adjust the PLT entry itself.
 566
 567       if (parameters->output_is_shared())
 568         {
 569           memcpy(pov, dyn_plt_entry, plt_entry_size);
 570           elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
 571         }
 572       else
 573         {
 574           memcpy(pov, exec_plt_entry, plt_entry_size);
 575           elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 576                                                       (got_address
 577                                                        + got_offset));
 578         }
 579
 580       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
 581       elfcpp::Swap<32, false>::writeval(pov + 12,
 582                                         - (plt_offset + plt_entry_size));
 583
 584       // Set the entry in the GOT.
 585       elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6);
 586     }
 587
 588   gold_assert(pov - oview == oview_size);
 589   gold_assert(got_pov - got_view == got_size);
 590
 591   of->write_output_view(offset, oview_size, oview);
 592   of->write_output_view(got_file_offset, got_size, got_view);
 593 }
 594
 595 // Create a PLT entry for a global symbol.
 596
 597 void
 598 Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym)
 599 {
 600   if (gsym->has_plt_offset())
 601     return;
 602
 603   if (this->plt_ == NULL)
 604     {
 605       // Create the GOT sections first.
 606       this->got_section(symtab, layout);
 607
 608       this->plt_ = new Output_data_plt_i386(layout, this->got_plt_);
 609       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 610                                       (elfcpp::SHF_ALLOC
 611                                        | elfcpp::SHF_EXECINSTR),
 612                                       this->plt_);
 613     }
 614
 615   this->plt_->add_entry(gsym);
 616 }
 617
 618 // Handle a relocation against a non-function symbol defined in a
 619 // dynamic object.  The traditional way to handle this is to generate
 620 // a COPY relocation to copy the variable at runtime from the shared
 621 // object into the executable's data segment.  However, this is
 622 // undesirable in general, as if the size of the object changes in the
 623 // dynamic object, the executable will no longer work correctly.  If
 624 // this relocation is in a writable section, then we can create a
 625 // dynamic reloc and the dynamic linker will resolve it to the correct
 626 // address at runtime.  However, we do not want do that if the
 627 // relocation is in a read-only section, as it would prevent the
 628 // readonly segment from being shared.  And if we have to eventually
 629 // generate a COPY reloc, then any dynamic relocations will be
 630 // useless.  So this means that if this is a writable section, we need
 631 // to save the relocation until we see whether we have to create a
 632 // COPY relocation for this symbol for any other relocation.
 633
 634 void
 635 Target_i386::copy_reloc(const General_options* options,
 636                         Symbol_table* symtab,
 637                         Layout* layout,
 638                         Sized_relobj<32, false>* object,
 639                         unsigned int data_shndx, Symbol* gsym,
 640                         const elfcpp::Rel<32, false>& rel)
 641 {
 642   Sized_symbol<32>* ssym;
 643   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(32) (gsym
 644                                                         SELECT_SIZE(32));
 645
 646   if (!Copy_relocs<32, false>::need_copy_reloc(options, object,
 647                                                data_shndx, ssym))
 648     {
 649       // So far we do not need a COPY reloc.  Save this relocation.
 650       // If it turns out that we never need a COPY reloc for this
 651       // symbol, then we will emit the relocation.
 652       if (this->copy_relocs_ == NULL)
 653         this->copy_relocs_ = new Copy_relocs<32, false>();
 654       this->copy_relocs_->save(ssym, object, data_shndx, rel);
 655     }
 656   else
 657     {
 658       // Allocate space for this symbol in the .bss section.
 659
 660       elfcpp::Elf_types<32>::Elf_WXword symsize = ssym->symsize();
 661
 662       // There is no defined way to determine the required alignment
 663       // of the symbol.  We pick the alignment based on the size.  We
 664       // set an arbitrary maximum of 256.
 665       unsigned int align;
 666       for (align = 1; align < 512; align <<= 1)
 667         if ((symsize & align) != 0)
 668           break;
 669
 670       if (this->dynbss_ == NULL)
 671         {
 672           this->dynbss_ = new Output_data_space(align);
 673           layout->add_output_section_data(".bss",
 674                                           elfcpp::SHT_NOBITS,
 675                                           (elfcpp::SHF_ALLOC
 676                                            | elfcpp::SHF_WRITE),
 677                                           this->dynbss_);
 678         }
 679
 680       Output_data_space* dynbss = this->dynbss_;
 681
 682       if (align > dynbss->addralign())
 683         dynbss->set_space_alignment(align);
 684
 685       off_t dynbss_size = dynbss->data_size();
 686       dynbss_size = align_address(dynbss_size, align);
 687       off_t offset = dynbss_size;
 688       dynbss->set_space_size(dynbss_size + symsize);
 689
 690       symtab->define_with_copy_reloc(this, ssym, dynbss, offset);
 691
 692       // Add the COPY reloc.
 693       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
 694       rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset);
 695     }
 696 }
 697
 698 // Optimize the TLS relocation type based on what we know about the
 699 // symbol.  IS_FINAL is true if the final address of this symbol is
 700 // known at link time.
 701
 702 tls::Tls_optimization
 703 Target_i386::optimize_tls_reloc(bool is_final, int r_type)
 704 {
 705   // If we are generating a shared library, then we can't do anything
 706   // in the linker.
 707   if (parameters->output_is_shared())
 708     return tls::TLSOPT_NONE;
 709
 710   switch (r_type)
 711     {
 712     case elfcpp::R_386_TLS_GD:
 713     case elfcpp::R_386_TLS_GOTDESC:
 714     case elfcpp::R_386_TLS_DESC_CALL:
 715       // These are General-Dynamic which permits fully general TLS
 716       // access.  Since we know that we are generating an executable,
 717       // we can convert this to Initial-Exec.  If we also know that
 718       // this is a local symbol, we can further switch to Local-Exec.
 719       if (is_final)
 720         return tls::TLSOPT_TO_LE;
 721       return tls::TLSOPT_TO_IE;
 722
 723     case elfcpp::R_386_TLS_LDM:
 724       // This is Local-Dynamic, which refers to a local symbol in the
 725       // dynamic TLS block.  Since we know that we generating an
 726       // executable, we can switch to Local-Exec.
 727       return tls::TLSOPT_TO_LE;
 728
 729     case elfcpp::R_386_TLS_LDO_32:
 730       // Another type of Local-Dynamic relocation.
 731       return tls::TLSOPT_TO_LE;
 732
 733     case elfcpp::R_386_TLS_IE:
 734     case elfcpp::R_386_TLS_GOTIE:
 735     case elfcpp::R_386_TLS_IE_32:
 736       // These are Initial-Exec relocs which get the thread offset
 737       // from the GOT.  If we know that we are linking against the
 738       // local symbol, we can switch to Local-Exec, which links the
 739       // thread offset into the instruction.
 740       if (is_final)
 741         return tls::TLSOPT_TO_LE;
 742       return tls::TLSOPT_NONE;
 743
 744     case elfcpp::R_386_TLS_LE:
 745     case elfcpp::R_386_TLS_LE_32:
 746       // When we already have Local-Exec, there is nothing further we
 747       // can do.
 748       return tls::TLSOPT_NONE;
 749
 750     default:
 751       gold_unreachable();
 752     }
 753 }
 754
 755 // Report an unsupported relocation against a local symbol.
 756
 757 void
 758 Target_i386::Scan::unsupported_reloc_local(Sized_relobj<32, false>* object,
 759                                            unsigned int r_type)
 760 {
 761   gold_error(_("%s: unsupported reloc %u against local symbol"),
 762              object->name().c_str(), r_type);
 763 }
 764
 765 // Scan a relocation for a local symbol.
 766
 767 inline void
 768 Target_i386::Scan::local(const General_options&,
 769                          Symbol_table* symtab,
 770                          Layout* layout,
 771                          Target_i386* target,
 772                          Sized_relobj<32, false>* object,
 773                          unsigned int data_shndx,
 774                          const elfcpp::Rel<32, false>& reloc,
 775                          unsigned int r_type,
 776                          const elfcpp::Sym<32, false>&)
 777 {
 778   switch (r_type)
 779     {
 780     case elfcpp::R_386_NONE:
 781     case elfcpp::R_386_GNU_VTINHERIT:
 782     case elfcpp::R_386_GNU_VTENTRY:
 783       break;
 784
 785     case elfcpp::R_386_32:
 786       // If building a shared library (or a position-independent
 787       // executable), we need to create a dynamic relocation for
 788       // this location. The relocation applied at link time will
 789       // apply the link-time value, so we flag the location with
 790       // an R_386_RELATIVE relocation so the dynamic loader can
 791       // relocate it easily.
 792       if (parameters->output_is_position_independent())
 793         {
 794           Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 795           rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE, data_shndx,
 796                              reloc.get_r_offset());
 797         }
 798       break;
 799
 800     case elfcpp::R_386_16:
 801     case elfcpp::R_386_8:
 802       // If building a shared library (or a position-independent
 803       // executable), we need to create a dynamic relocation for
 804       // this location. Because the addend needs to remain in the
 805       // data section, we need to be careful not to apply this
 806       // relocation statically.
 807       if (parameters->output_is_position_independent())
 808         {
 809           Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 810           unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
 811           rel_dyn->add_local(object, r_sym, r_type, data_shndx,
 812                              reloc.get_r_offset());
 813         }
 814       break;
 815
 816     case elfcpp::R_386_PC32:
 817     case elfcpp::R_386_PC16:
 818     case elfcpp::R_386_PC8:
 819       break;
 820
 821     case elfcpp::R_386_PLT32:
 822       // Since we know this is a local symbol, we can handle this as a
 823       // PC32 reloc.
 824       break;
 825
 826     case elfcpp::R_386_GOTOFF:
 827     case elfcpp::R_386_GOTPC:
 828       // We need a GOT section.
 829       target->got_section(symtab, layout);
 830       break;
 831
 832     case elfcpp::R_386_GOT32:
 833       {
 834         // The symbol requires a GOT entry.
 835         Output_data_got<32, false>* got = target->got_section(symtab, layout);
 836         unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
 837         if (got->add_local(object, r_sym))
 838           {
 839             // If we are generating a shared object, we need to add a
 840             // dynamic RELATIVE relocation for this symbol.
 841             if (parameters->output_is_position_independent())
 842               {
 843                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 844                 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE,
 845                                    data_shndx, reloc.get_r_offset());
 846               }
 847           }
 848       }
 849       break;
 850
 851       // These are relocations which should only be seen by the
 852       // dynamic linker, and should never be seen here.
 853     case elfcpp::R_386_COPY:
 854     case elfcpp::R_386_GLOB_DAT:
 855     case elfcpp::R_386_JUMP_SLOT:
 856     case elfcpp::R_386_RELATIVE:
 857     case elfcpp::R_386_TLS_TPOFF:
 858     case elfcpp::R_386_TLS_DTPMOD32:
 859     case elfcpp::R_386_TLS_DTPOFF32:
 860     case elfcpp::R_386_TLS_TPOFF32:
 861     case elfcpp::R_386_TLS_DESC:
 862       gold_error(_("%s: unexpected reloc %u in object file"),
 863                  object->name().c_str(), r_type);
 864       break;
 865
 866       // These are initial TLS relocs, which are expected when
 867       // linking.
 868     case elfcpp::R_386_TLS_GD:            // Global-dynamic
 869     case elfcpp::R_386_TLS_GOTDESC:       // Global-dynamic (from ~oliva url)
 870     case elfcpp::R_386_TLS_DESC_CALL:
 871     case elfcpp::R_386_TLS_LDM:           // Local-dynamic
 872     case elfcpp::R_386_TLS_LDO_32:        // Alternate local-dynamic
 873     case elfcpp::R_386_TLS_IE:            // Initial-exec
 874     case elfcpp::R_386_TLS_IE_32:
 875     case elfcpp::R_386_TLS_GOTIE:
 876     case elfcpp::R_386_TLS_LE:            // Local-exec
 877     case elfcpp::R_386_TLS_LE_32:
 878       {
 879         bool output_is_shared = parameters->output_is_shared();
 880         const tls::Tls_optimization optimized_type
 881             = Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
 882         switch (r_type)
 883           {
 884           case elfcpp::R_386_TLS_GD:          // Global-dynamic
 885           case elfcpp::R_386_TLS_GOTDESC:     // Global-dynamic (from ~oliva)
 886           case elfcpp::R_386_TLS_DESC_CALL:
 887             // FIXME: If not relaxing to LE, we need to generate
 888             // DTPMOD32 and DTPOFF32 relocs.
 889             if (optimized_type != tls::TLSOPT_TO_LE)
 890               unsupported_reloc_local(object, r_type);
 891             break;
 892
 893           case elfcpp::R_386_TLS_LDM:         // Local-dynamic
 894             // FIXME: If not relaxing to LE, we need to generate a
 895             // DTPMOD32 reloc.
 896             if (optimized_type != tls::TLSOPT_TO_LE)
 897               unsupported_reloc_local(object, r_type);
 898             break;
 899
 900           case elfcpp::R_386_TLS_LDO_32:      // Alternate local-dynamic
 901             break;
 902
 903           case elfcpp::R_386_TLS_IE:          // Initial-exec
 904           case elfcpp::R_386_TLS_IE_32:
 905           case elfcpp::R_386_TLS_GOTIE:
 906             // FIXME: If not relaxing to LE, we need to generate a
 907             // TPOFF or TPOFF32 reloc.
 908             if (optimized_type != tls::TLSOPT_TO_LE)
 909               unsupported_reloc_local(object, r_type);
 910             break;
 911
 912           case elfcpp::R_386_TLS_LE:          // Local-exec
 913           case elfcpp::R_386_TLS_LE_32:
 914             // FIXME: If generating a shared object, we need to copy
 915             // this relocation into the object.
 916             gold_assert(!output_is_shared);
 917             break;
 918
 919           default:
 920             gold_unreachable();
 921           }
 922       }
 923       break;
 924
 925     case elfcpp::R_386_32PLT:
 926     case elfcpp::R_386_TLS_GD_32:
 927     case elfcpp::R_386_TLS_GD_PUSH:
 928     case elfcpp::R_386_TLS_GD_CALL:
 929     case elfcpp::R_386_TLS_GD_POP:
 930     case elfcpp::R_386_TLS_LDM_32:
 931     case elfcpp::R_386_TLS_LDM_PUSH:
 932     case elfcpp::R_386_TLS_LDM_CALL:
 933     case elfcpp::R_386_TLS_LDM_POP:
 934     case elfcpp::R_386_USED_BY_INTEL_200:
 935     default:
 936       unsupported_reloc_local(object, r_type);
 937       break;
 938     }
 939 }
 940
 941 // Report an unsupported relocation against a global symbol.
 942
 943 void
 944 Target_i386::Scan::unsupported_reloc_global(Sized_relobj<32, false>* object,
 945                                             unsigned int r_type,
 946                                             Symbol* gsym)
 947 {
 948   gold_error(_("%s: unsupported reloc %u against global symbol %s"),
 949              object->name().c_str(), r_type, gsym->name());
 950 }
 951
 952 // Scan a relocation for a global symbol.
 953
 954 inline void
 955 Target_i386::Scan::global(const General_options& options,
 956                           Symbol_table* symtab,
 957                           Layout* layout,
 958                           Target_i386* target,
 959                           Sized_relobj<32, false>* object,
 960                           unsigned int data_shndx,
 961                           const elfcpp::Rel<32, false>& reloc,
 962                           unsigned int r_type,
 963                           Symbol* gsym)
 964 {
 965   switch (r_type)
 966     {
 967     case elfcpp::R_386_NONE:
 968     case elfcpp::R_386_GNU_VTINHERIT:
 969     case elfcpp::R_386_GNU_VTENTRY:
 970       break;
 971
 972     case elfcpp::R_386_32:
 973     case elfcpp::R_386_16:
 974     case elfcpp::R_386_8:
 975       {
 976         // Make a PLT entry if necessary.
 977         if (gsym->needs_plt_entry())
 978           {
 979             target->make_plt_entry(symtab, layout, gsym);
 980             // Since this is not a PC-relative relocation, we may be
 981             // taking the address of a function. In that case we need to
 982             // set the entry in the dynamic symbol table to the address of
 983             // the PLT entry.
 984             if (gsym->is_from_dynobj())
 985               gsym->set_needs_dynsym_value();
 986           }
 987         // Make a dynamic relocation if necessary.
 988         if (gsym->needs_dynamic_reloc(true, false))
 989           {
 990             if (target->may_need_copy_reloc(gsym))
 991               {
 992                 target->copy_reloc(&options, symtab, layout, object, data_shndx,
 993                                    gsym, reloc);
 994               }
 995             else if (r_type == elfcpp::R_386_32
 996                      && gsym->can_use_relative_reloc(false))
 997               {
 998                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 999                 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE, data_shndx,
1000                                    reloc.get_r_offset());
1001               }
1002             else
1003               {
1004                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1005                 rel_dyn->add_global(gsym, r_type, object, data_shndx,
1006                                     reloc.get_r_offset());
1007               }
1008           }
1009       }
1010       break;
1011
1012     case elfcpp::R_386_PC32:
1013     case elfcpp::R_386_PC16:
1014     case elfcpp::R_386_PC8:
1015       {
1016         // Make a PLT entry if necessary.
1017         if (gsym->needs_plt_entry())
1018           target->make_plt_entry(symtab, layout, gsym);
1019         // Make a dynamic relocation if necessary.
1020         bool is_function_call = (gsym->type() == elfcpp::STT_FUNC);
1021         if (gsym->needs_dynamic_reloc(false, is_function_call))
1022           {
1023             if (target->may_need_copy_reloc(gsym))
1024               {
1025                 target->copy_reloc(&options, symtab, layout, object, data_shndx,
1026                                    gsym, reloc);
1027               }
1028             else
1029               {
1030                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1031                 rel_dyn->add_global(gsym, r_type, object, data_shndx,
1032                                     reloc.get_r_offset());
1033               }
1034           }
1035       }
1036       break;
1037
1038     case elfcpp::R_386_GOT32:
1039       {
1040         // The symbol requires a GOT entry.
1041         Output_data_got<32, false>* got = target->got_section(symtab, layout);
1042         if (got->add_global(gsym))
1043           {
1044             // If this symbol is not fully resolved, we need to add a
1045             // dynamic relocation for it.
1046             if (!gsym->final_value_is_known())
1047               {
1048                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1049                 if (gsym->is_from_dynobj()
1050                     || gsym->is_preemptible())
1051                   rel_dyn->add_global(gsym, elfcpp::R_386_GLOB_DAT, got,
1052                                       gsym->got_offset());
1053                 else
1054                   {
1055                     rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE,
1056                                        got, gsym->got_offset());
1057                     // Make sure we write the link-time value to the GOT.
1058                     gsym->set_needs_value_in_got();
1059                   }
1060               }
1061           }
1062       }
1063       break;
1064
1065     case elfcpp::R_386_PLT32:
1066       // If the symbol is fully resolved, this is just a PC32 reloc.
1067       // Otherwise we need a PLT entry.
1068       if (gsym->final_value_is_known())
1069         break;
1070       // If building a shared library, we can also skip the PLT entry
1071       // if the symbol is defined in the output file and is protected
1072       // or hidden.
1073       if (gsym->is_defined()
1074           && !gsym->is_from_dynobj()
1075           && !gsym->is_preemptible())
1076         break;
1077       target->make_plt_entry(symtab, layout, gsym);
1078       break;
1079
1080     case elfcpp::R_386_GOTOFF:
1081     case elfcpp::R_386_GOTPC:
1082       // We need a GOT section.
1083       target->got_section(symtab, layout);
1084       break;
1085
1086       // These are relocations which should only be seen by the
1087       // dynamic linker, and should never be seen here.
1088     case elfcpp::R_386_COPY:
1089     case elfcpp::R_386_GLOB_DAT:
1090     case elfcpp::R_386_JUMP_SLOT:
1091     case elfcpp::R_386_RELATIVE:
1092     case elfcpp::R_386_TLS_TPOFF:
1093     case elfcpp::R_386_TLS_DTPMOD32:
1094     case elfcpp::R_386_TLS_DTPOFF32:
1095     case elfcpp::R_386_TLS_TPOFF32:
1096     case elfcpp::R_386_TLS_DESC:
1097       gold_error(_("%s: unexpected reloc %u in object file"),
1098                  object->name().c_str(), r_type);
1099       break;
1100
1101       // These are initial tls relocs, which are expected when
1102       // linking.
1103     case elfcpp::R_386_TLS_GD:            // Global-dynamic
1104     case elfcpp::R_386_TLS_GOTDESC:       // Global-dynamic (from ~oliva url)
1105     case elfcpp::R_386_TLS_DESC_CALL:
1106     case elfcpp::R_386_TLS_LDM:           // Local-dynamic
1107     case elfcpp::R_386_TLS_LDO_32:        // Alternate local-dynamic
1108     case elfcpp::R_386_TLS_IE:            // Initial-exec
1109     case elfcpp::R_386_TLS_IE_32:
1110     case elfcpp::R_386_TLS_GOTIE:
1111     case elfcpp::R_386_TLS_LE:            // Local-exec
1112     case elfcpp::R_386_TLS_LE_32:
1113       {
1114         const bool is_final = gsym->final_value_is_known();
1115         const tls::Tls_optimization optimized_type
1116             = Target_i386::optimize_tls_reloc(is_final, r_type);
1117         switch (r_type)
1118           {
1119           case elfcpp::R_386_TLS_GD:          // Global-dynamic
1120           case elfcpp::R_386_TLS_GOTDESC:     // Global-dynamic (~oliva url)
1121           case elfcpp::R_386_TLS_DESC_CALL:
1122             // FIXME: If not relaxing to LE, we need to generate
1123             // DTPMOD32 and DTPOFF32 relocs.
1124             if (optimized_type != tls::TLSOPT_TO_LE)
1125               unsupported_reloc_global(object, r_type, gsym);
1126             break;
1127
1128           case elfcpp::R_386_TLS_LDM:         // Local-dynamic
1129             // FIXME: If not relaxing to LE, we need to generate a
1130             // DTPMOD32 reloc.
1131             if (optimized_type != tls::TLSOPT_TO_LE)
1132               unsupported_reloc_global(object, r_type, gsym);
1133             break;
1134
1135           case elfcpp::R_386_TLS_LDO_32:      // Alternate local-dynamic
1136             break;
1137
1138           case elfcpp::R_386_TLS_IE:          // Initial-exec
1139           case elfcpp::R_386_TLS_IE_32:
1140           case elfcpp::R_386_TLS_GOTIE:
1141             // FIXME: If not relaxing to LE, we need to generate a
1142             // TPOFF or TPOFF32 reloc.
1143             if (optimized_type != tls::TLSOPT_TO_LE)
1144               unsupported_reloc_global(object, r_type, gsym);
1145             break;
1146
1147           case elfcpp::R_386_TLS_LE:          // Local-exec
1148           case elfcpp::R_386_TLS_LE_32:
1149             // FIXME: If generating a shared object, we need to copy
1150             // this relocation into the object.
1151             gold_assert(!parameters->output_is_shared());
1152             break;
1153
1154           default:
1155             gold_unreachable();
1156           }
1157       }
1158       break;
1159
1160     case elfcpp::R_386_32PLT:
1161     case elfcpp::R_386_TLS_GD_32:
1162     case elfcpp::R_386_TLS_GD_PUSH:
1163     case elfcpp::R_386_TLS_GD_CALL:
1164     case elfcpp::R_386_TLS_GD_POP:
1165     case elfcpp::R_386_TLS_LDM_32:
1166     case elfcpp::R_386_TLS_LDM_PUSH:
1167     case elfcpp::R_386_TLS_LDM_CALL:
1168     case elfcpp::R_386_TLS_LDM_POP:
1169     case elfcpp::R_386_USED_BY_INTEL_200:
1170     default:
1171       unsupported_reloc_global(object, r_type, gsym);
1172       break;
1173     }
1174 }
1175
1176 // Scan relocations for a section.
1177
1178 void
1179 Target_i386::scan_relocs(const General_options& options,
1180                          Symbol_table* symtab,
1181                          Layout* layout,
1182                          Sized_relobj<32, false>* object,
1183                          unsigned int data_shndx,
1184                          unsigned int sh_type,
1185                          const unsigned char* prelocs,
1186                          size_t reloc_count,
1187                          Output_section* output_section,
1188                          bool needs_special_offset_handling,
1189                          size_t local_symbol_count,
1190                          const unsigned char* plocal_symbols)
1191 {
1192   if (sh_type == elfcpp::SHT_RELA)
1193     {
1194       gold_error(_("%s: unsupported RELA reloc section"),
1195                  object->name().c_str());
1196       return;
1197     }
1198
1199   gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
1200                     Target_i386::Scan>(
1201     options,
1202     symtab,
1203     layout,
1204     this,
1205     object,
1206     data_shndx,
1207     prelocs,
1208     reloc_count,
1209     output_section,
1210     needs_special_offset_handling,
1211     local_symbol_count,
1212     plocal_symbols);
1213 }
1214
1215 // Finalize the sections.
1216
1217 void
1218 Target_i386::do_finalize_sections(Layout* layout)
1219 {
1220   // Fill in some more dynamic tags.
1221   Output_data_dynamic* const odyn = layout->dynamic_data();
1222   if (odyn != NULL)
1223     {
1224       if (this->got_plt_ != NULL)
1225         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1226
1227       if (this->plt_ != NULL)
1228         {
1229           const Output_data* od = this->plt_->rel_plt();
1230           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1231           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1232           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL);
1233         }
1234
1235       if (this->rel_dyn_ != NULL)
1236         {
1237           const Output_data* od = this->rel_dyn_;
1238           odyn->add_section_address(elfcpp::DT_REL, od);
1239           odyn->add_section_size(elfcpp::DT_RELSZ, od);
1240           odyn->add_constant(elfcpp::DT_RELENT,
1241                              elfcpp::Elf_sizes<32>::rel_size);
1242         }
1243
1244       if (!parameters->output_is_shared())
1245         {
1246           // The value of the DT_DEBUG tag is filled in by the dynamic
1247           // linker at run time, and used by the debugger.
1248           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1249         }
1250     }
1251
1252   // Emit any relocs we saved in an attempt to avoid generating COPY
1253   // relocs.
1254   if (this->copy_relocs_ == NULL)
1255     return;
1256   if (this->copy_relocs_->any_to_emit())
1257     {
1258       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1259       this->copy_relocs_->emit(rel_dyn);
1260     }
1261   delete this->copy_relocs_;
1262   this->copy_relocs_ = NULL;
1263 }
1264
1265 // Return whether a direct absolute static relocation needs to be applied.
1266 // In cases where Scan::local() or Scan::global() has created
1267 // a dynamic relocation other than R_386_RELATIVE, the addend
1268 // of the relocation is carried in the data, and we must not
1269 // apply the static relocation.
1270
1271 inline bool
1272 Target_i386::Relocate::should_apply_static_reloc(const Sized_symbol<32>* gsym,
1273                                                  bool is_absolute_ref,
1274                                                  bool is_function_call,
1275                                                  bool is_32bit)
1276 {
1277   // For local symbols, we will have created a non-RELATIVE dynamic
1278   // relocation only if (a) the output is position independent,
1279   // (b) the relocation is absolute (not pc- or segment-relative), and
1280   // (c) the relocation is not 32 bits wide.
1281   if (gsym == NULL)
1282     return !(parameters->output_is_position_independent()
1283              && is_absolute_ref
1284              && !is_32bit);
1285
1286   // For global symbols, we use the same helper routines used in the scan pass.
1287   return !(gsym->needs_dynamic_reloc(is_absolute_ref, is_function_call)
1288            && !gsym->can_use_relative_reloc(is_function_call));
1289 }
1290
1291 // Perform a relocation.
1292
1293 inline bool
1294 Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
1295                                 Target_i386* target,
1296                                 size_t relnum,
1297                                 const elfcpp::Rel<32, false>& rel,
1298                                 unsigned int r_type,
1299                                 const Sized_symbol<32>* gsym,
1300                                 const Symbol_value<32>* psymval,
1301                                 unsigned char* view,
1302                                 elfcpp::Elf_types<32>::Elf_Addr address,
1303                                 off_t view_size)
1304 {
1305   if (this->skip_call_tls_get_addr_)
1306     {
1307       if (r_type != elfcpp::R_386_PLT32
1308           || gsym == NULL
1309           || strcmp(gsym->name(), "___tls_get_addr") != 0)
1310         gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1311                                _("missing expected TLS relocation"));
1312       else
1313         {
1314           this->skip_call_tls_get_addr_ = false;
1315           return false;
1316         }
1317     }
1318
1319   // Pick the value to use for symbols defined in shared objects.
1320   Symbol_value<32> symval;
1321   if (gsym != NULL
1322       && (gsym->is_from_dynobj()
1323           || (parameters->output_is_shared()
1324               && gsym->is_preemptible()))
1325       && gsym->has_plt_offset())
1326     {
1327       symval.set_output_value(target->plt_section()->address()
1328                               + gsym->plt_offset());
1329       psymval = &symval;
1330     }
1331
1332   const Sized_relobj<32, false>* object = relinfo->object;
1333
1334   // Get the GOT offset if needed.
1335   // The GOT pointer points to the end of the GOT section.
1336   // We need to subtract the size of the GOT section to get
1337   // the actual offset to use in the relocation.
1338   bool have_got_offset = false;
1339   unsigned int got_offset = 0;
1340   switch (r_type)
1341     {
1342     case elfcpp::R_386_GOT32:
1343       if (gsym != NULL)
1344         {
1345           gold_assert(gsym->has_got_offset());
1346           got_offset = gsym->got_offset() - target->got_size();
1347         }
1348       else
1349         {
1350           unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1351           got_offset = object->local_got_offset(r_sym) - target->got_size();
1352         }
1353       have_got_offset = true;
1354       break;
1355
1356     default:
1357       break;
1358     }
1359
1360   switch (r_type)
1361     {
1362     case elfcpp::R_386_NONE:
1363     case elfcpp::R_386_GNU_VTINHERIT:
1364     case elfcpp::R_386_GNU_VTENTRY:
1365       break;
1366
1367     case elfcpp::R_386_32:
1368       if (should_apply_static_reloc(gsym, true, false, true))
1369         Relocate_functions<32, false>::rel32(view, object, psymval);
1370       break;
1371
1372     case elfcpp::R_386_PC32:
1373       {
1374         bool is_function_call = (gsym != NULL
1375                                  && gsym->type() == elfcpp::STT_FUNC);
1376         if (should_apply_static_reloc(gsym, false, is_function_call, true))
1377           Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1378       }
1379       break;
1380
1381     case elfcpp::R_386_16:
1382       if (should_apply_static_reloc(gsym, true, false, false))
1383         Relocate_functions<32, false>::rel16(view, object, psymval);
1384       break;
1385
1386     case elfcpp::R_386_PC16:
1387       {
1388         bool is_function_call = (gsym != NULL
1389                                  && gsym->type() == elfcpp::STT_FUNC);
1390         if (should_apply_static_reloc(gsym, false, is_function_call, false))
1391           Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1392       }
1393       break;
1394
1395     case elfcpp::R_386_8:
1396       if (should_apply_static_reloc(gsym, true, false, false))
1397         Relocate_functions<32, false>::rel8(view, object, psymval);
1398       break;
1399
1400     case elfcpp::R_386_PC8:
1401       {
1402         bool is_function_call = (gsym != NULL
1403                                  && gsym->type() == elfcpp::STT_FUNC);
1404         if (should_apply_static_reloc(gsym, false, is_function_call, false))
1405           Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1406       }
1407       break;
1408
1409     case elfcpp::R_386_PLT32:
1410       gold_assert(gsym == NULL
1411                   || gsym->has_plt_offset()
1412                   || gsym->final_value_is_known());
1413       Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1414       break;
1415
1416     case elfcpp::R_386_GOT32:
1417       gold_assert(have_got_offset);
1418       Relocate_functions<32, false>::rel32(view, got_offset);
1419       break;
1420
1421     case elfcpp::R_386_GOTOFF:
1422       {
1423         elfcpp::Elf_types<32>::Elf_Addr value;
1424         value = (psymval->value(object, 0)
1425                  - target->got_plt_section()->address());
1426         Relocate_functions<32, false>::rel32(view, value);
1427       }
1428       break;
1429
1430     case elfcpp::R_386_GOTPC:
1431       {
1432         elfcpp::Elf_types<32>::Elf_Addr value;
1433         value = target->got_plt_section()->address();
1434         Relocate_functions<32, false>::pcrel32(view, value, address);
1435       }
1436       break;
1437
1438     case elfcpp::R_386_COPY:
1439     case elfcpp::R_386_GLOB_DAT:
1440     case elfcpp::R_386_JUMP_SLOT:
1441     case elfcpp::R_386_RELATIVE:
1442       // These are outstanding tls relocs, which are unexpected when
1443       // linking.
1444     case elfcpp::R_386_TLS_TPOFF:
1445     case elfcpp::R_386_TLS_DTPMOD32:
1446     case elfcpp::R_386_TLS_DTPOFF32:
1447     case elfcpp::R_386_TLS_TPOFF32:
1448     case elfcpp::R_386_TLS_DESC:
1449       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1450                              _("unexpected reloc %u in object file"),
1451                              r_type);
1452       break;
1453
1454       // These are initial tls relocs, which are expected when
1455       // linking.
1456     case elfcpp::R_386_TLS_GD:             // Global-dynamic
1457     case elfcpp::R_386_TLS_GOTDESC:        // Global-dynamic (from ~oliva url)
1458     case elfcpp::R_386_TLS_DESC_CALL:
1459     case elfcpp::R_386_TLS_LDM:            // Local-dynamic
1460     case elfcpp::R_386_TLS_LDO_32:         // Alternate local-dynamic
1461     case elfcpp::R_386_TLS_IE:             // Initial-exec
1462     case elfcpp::R_386_TLS_IE_32:
1463     case elfcpp::R_386_TLS_GOTIE:
1464     case elfcpp::R_386_TLS_LE:             // Local-exec
1465     case elfcpp::R_386_TLS_LE_32:
1466       this->relocate_tls(relinfo, relnum, rel, r_type, gsym, psymval, view,
1467                          address, view_size);
1468       break;
1469
1470     case elfcpp::R_386_32PLT:
1471     case elfcpp::R_386_TLS_GD_32:
1472     case elfcpp::R_386_TLS_GD_PUSH:
1473     case elfcpp::R_386_TLS_GD_CALL:
1474     case elfcpp::R_386_TLS_GD_POP:
1475     case elfcpp::R_386_TLS_LDM_32:
1476     case elfcpp::R_386_TLS_LDM_PUSH:
1477     case elfcpp::R_386_TLS_LDM_CALL:
1478     case elfcpp::R_386_TLS_LDM_POP:
1479     case elfcpp::R_386_USED_BY_INTEL_200:
1480     default:
1481       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1482                              _("unsupported reloc %u"),
1483                              r_type);
1484       break;
1485     }
1486
1487   return true;
1488 }
1489
1490 // Perform a TLS relocation.
1491
1492 inline void
1493 Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
1494                                     size_t relnum,
1495                                     const elfcpp::Rel<32, false>& rel,
1496                                     unsigned int r_type,
1497                                     const Sized_symbol<32>* gsym,
1498                                     const Symbol_value<32>* psymval,
1499                                     unsigned char* view,
1500                                     elfcpp::Elf_types<32>::Elf_Addr,
1501                                     off_t view_size)
1502 {
1503   Output_segment* tls_segment = relinfo->layout->tls_segment();
1504   if (tls_segment == NULL)
1505     {
1506       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1507                              _("TLS reloc but no TLS segment"));
1508       return;
1509     }
1510
1511   elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(relinfo->object, 0);
1512
1513   const bool is_final = (gsym == NULL
1514                          ? !parameters->output_is_position_independent()
1515                          : gsym->final_value_is_known());
1516   const tls::Tls_optimization optimized_type
1517       = Target_i386::optimize_tls_reloc(is_final, r_type);
1518   switch (r_type)
1519     {
1520     case elfcpp::R_386_TLS_GD:           // Global-dynamic
1521       if (optimized_type == tls::TLSOPT_TO_LE)
1522         {
1523           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1524                              rel, r_type, value, view,
1525                              view_size);
1526           break;
1527         }
1528       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1529                              _("unsupported reloc %u"),
1530                              r_type);
1531       break;
1532
1533     case elfcpp::R_386_TLS_GOTDESC:      // Global-dynamic (from ~oliva url)
1534     case elfcpp::R_386_TLS_DESC_CALL:
1535       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1536                              _("unsupported reloc %u"),
1537                              r_type);
1538       break;
1539
1540     case elfcpp::R_386_TLS_LDM:          // Local-dynamic
1541       if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
1542         {
1543           gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1544                                  _("both SUN and GNU model "
1545                                    "TLS relocations"));
1546           break;
1547         }
1548       this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
1549       if (optimized_type == tls::TLSOPT_TO_LE)
1550         {
1551           this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
1552                              value, view, view_size);
1553           break;
1554         }
1555       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1556                              _("unsupported reloc %u"),
1557                              r_type);
1558       break;
1559
1560     case elfcpp::R_386_TLS_LDO_32:       // Alternate local-dynamic
1561       // This reloc can appear in debugging sections, in which case we
1562       // won't see the TLS_LDM reloc.  The local_dynamic_type field
1563       // tells us this.
1564       if (optimized_type != tls::TLSOPT_TO_LE
1565           || this->local_dynamic_type_ == LOCAL_DYNAMIC_NONE)
1566         value = value - tls_segment->vaddr();
1567       else if (this->local_dynamic_type_ == LOCAL_DYNAMIC_GNU)
1568         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1569       else
1570         value = tls_segment->vaddr() + tls_segment->memsz() - value;
1571       Relocate_functions<32, false>::rel32(view, value);
1572       break;
1573
1574     case elfcpp::R_386_TLS_IE:           // Initial-exec
1575     case elfcpp::R_386_TLS_GOTIE:
1576     case elfcpp::R_386_TLS_IE_32:
1577       if (optimized_type == tls::TLSOPT_TO_LE)
1578         {
1579           Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1580                                               rel, r_type, value, view,
1581                                               view_size);
1582           break;
1583         }
1584       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1585                              _("unsupported reloc %u"),
1586                              r_type);
1587       break;
1588
1589     case elfcpp::R_386_TLS_LE:           // Local-exec
1590       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1591       Relocate_functions<32, false>::rel32(view, value);
1592       break;
1593
1594     case elfcpp::R_386_TLS_LE_32:
1595       value = tls_segment->vaddr() + tls_segment->memsz() - value;
1596       Relocate_functions<32, false>::rel32(view, value);
1597       break;
1598     }
1599 }
1600
1601 // Do a relocation in which we convert a TLS General-Dynamic to a
1602 // Local-Exec.
1603
1604 inline void
1605 Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
1606                                     size_t relnum,
1607                                     Output_segment* tls_segment,
1608                                     const elfcpp::Rel<32, false>& rel,
1609                                     unsigned int,
1610                                     elfcpp::Elf_types<32>::Elf_Addr value,
1611                                     unsigned char* view,
1612                                     off_t view_size)
1613 {
1614   // leal foo(,%reg,1),%eax; call ___tls_get_addr
1615   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1616   // leal foo(%reg),%eax; call ___tls_get_addr
1617   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1618
1619   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1620   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1621
1622   unsigned char op1 = view[-1];
1623   unsigned char op2 = view[-2];
1624
1625   tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1626                  op2 == 0x8d || op2 == 0x04);
1627   tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1628
1629   int roff = 5;
1630
1631   if (op2 == 0x04)
1632     {
1633       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
1634       tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
1635       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1636                      ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
1637       memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1638     }
1639   else
1640     {
1641       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1642                      (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1643       if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
1644           && view[9] == 0x90)
1645         {
1646           // There is a trailing nop.  Use the size byte subl.
1647           memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1648           roff = 6;
1649         }
1650       else
1651         {
1652           // Use the five byte subl.
1653           memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1654         }
1655     }
1656
1657   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1658   Relocate_functions<32, false>::rel32(view + roff, value);
1659
1660   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1661   // We can skip it.
1662   this->skip_call_tls_get_addr_ = true;
1663 }
1664
1665 // Do a relocation in which we convert a TLS Local-Dynamic to a
1666 // Local-Exec.
1667
1668 inline void
1669 Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
1670                                     size_t relnum,
1671                                     Output_segment*,
1672                                     const elfcpp::Rel<32, false>& rel,
1673                                     unsigned int,
1674                                     elfcpp::Elf_types<32>::Elf_Addr,
1675                                     unsigned char* view,
1676                                     off_t view_size)
1677 {
1678   // leal foo(%reg), %eax; call ___tls_get_addr
1679   // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
1680
1681   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1682   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1683
1684   // FIXME: Does this test really always pass?
1685   tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1686                  view[-2] == 0x8d && view[-1] == 0x83);
1687
1688   tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1689
1690   memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
1691
1692   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1693   // We can skip it.
1694   this->skip_call_tls_get_addr_ = true;
1695 }
1696
1697 // Do a relocation in which we convert a TLS Initial-Exec to a
1698 // Local-Exec.
1699
1700 inline void
1701 Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
1702                                     size_t relnum,
1703                                     Output_segment* tls_segment,
1704                                     const elfcpp::Rel<32, false>& rel,
1705                                     unsigned int r_type,
1706                                     elfcpp::Elf_types<32>::Elf_Addr value,
1707                                     unsigned char* view,
1708                                     off_t view_size)
1709 {
1710   // We have to actually change the instructions, which means that we
1711   // need to examine the opcodes to figure out which instruction we
1712   // are looking at.
1713   if (r_type == elfcpp::R_386_TLS_IE)
1714     {
1715       // movl %gs:XX,%eax  ==>  movl $YY,%eax
1716       // movl %gs:XX,%reg  ==>  movl $YY,%reg
1717       // addl %gs:XX,%reg  ==>  addl $YY,%reg
1718       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
1719       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
1720
1721       unsigned char op1 = view[-1];
1722       if (op1 == 0xa1)
1723         {
1724           // movl XX,%eax  ==>  movl $YY,%eax
1725           view[-1] = 0xb8;
1726         }
1727       else
1728         {
1729           tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1730
1731           unsigned char op2 = view[-2];
1732           if (op2 == 0x8b)
1733             {
1734               // movl XX,%reg  ==>  movl $YY,%reg
1735               tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1736                              (op1 & 0xc7) == 0x05);
1737               view[-2] = 0xc7;
1738               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1739             }
1740           else if (op2 == 0x03)
1741             {
1742               // addl XX,%reg  ==>  addl $YY,%reg
1743               tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1744                              (op1 & 0xc7) == 0x05);
1745               view[-2] = 0x81;
1746               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1747             }
1748           else
1749             tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
1750         }
1751     }
1752   else
1753     {
1754       // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1755       // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1756       // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1757       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1758       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
1759
1760       unsigned char op1 = view[-1];
1761       unsigned char op2 = view[-2];
1762       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1763                      (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
1764       if (op2 == 0x8b)
1765         {
1766           // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1767           view[-2] = 0xc7;
1768           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1769         }
1770       else if (op2 == 0x2b)
1771         {
1772           // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1773           view[-2] = 0x81;
1774           view[-1] = 0xe8 | ((op1 >> 3) & 7);
1775         }
1776       else if (op2 == 0x03)
1777         {
1778           // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1779           view[-2] = 0x81;
1780           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1781         }
1782       else
1783         tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
1784     }
1785
1786   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1787   if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
1788     value = - value;
1789
1790   Relocate_functions<32, false>::rel32(view, value);
1791 }
1792
1793 // Relocate section data.
1794
1795 void
1796 Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
1797                               unsigned int sh_type,
1798                               const unsigned char* prelocs,
1799                               size_t reloc_count,
1800                               Output_section* output_section,
1801                               bool needs_special_offset_handling,
1802                               unsigned char* view,
1803                               elfcpp::Elf_types<32>::Elf_Addr address,
1804                               off_t view_size)
1805 {
1806   gold_assert(sh_type == elfcpp::SHT_REL);
1807
1808   gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
1809                          Target_i386::Relocate>(
1810     relinfo,
1811     this,
1812     prelocs,
1813     reloc_count,
1814     output_section,
1815     needs_special_offset_handling,
1816     view,
1817     address,
1818     view_size);
1819 }
1820
1821 // Return the value to use for a dynamic which requires special
1822 // treatment.  This is how we support equality comparisons of function
1823 // pointers across shared library boundaries, as described in the
1824 // processor specific ABI supplement.
1825
1826 uint64_t
1827 Target_i386::do_dynsym_value(const Symbol* gsym) const
1828 {
1829   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1830   return this->plt_section()->address() + gsym->plt_offset();
1831 }
1832
1833 // Return a string used to fill a code section with nops to take up
1834 // the specified length.
1835
1836 std::string
1837 Target_i386::do_code_fill(off_t length)
1838 {
1839   if (length >= 16)
1840     {
1841       // Build a jmp instruction to skip over the bytes.
1842       unsigned char jmp[5];
1843       jmp[0] = 0xe9;
1844       elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
1845       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1846               + std::string(length - 5, '\0'));
1847     }
1848
1849   // Nop sequences of various lengths.
1850   const char nop1[1] = { 0x90 };                   // nop
1851   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1852   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1853   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1854   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1855                          0x00 };                   // leal 0(%esi,1),%esi
1856   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1857                          0x00, 0x00 };
1858   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1859                          0x00, 0x00, 0x00 };
1860   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1861                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1862   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1863                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1864                          0x00 };
1865   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1866                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1867                            0x00, 0x00 };
1868   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1869                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1870                            0x00, 0x00, 0x00 };
1871   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1872                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1873                            0x00, 0x00, 0x00, 0x00 };
1874   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1875                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1876                            0x27, 0x00, 0x00, 0x00,
1877                            0x00 };
1878   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1879                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1880                            0xbc, 0x27, 0x00, 0x00,
1881                            0x00, 0x00 };
1882   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1883                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1884                            0x90, 0x90, 0x90, 0x90,
1885                            0x90, 0x90, 0x90 };
1886
1887   const char* nops[16] = {
1888     NULL,
1889     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1890     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1891   };
1892
1893   return std::string(nops[length], length);
1894 }
1895
1896 // The selector for i386 object files.
1897
1898 class Target_selector_i386 : public Target_selector
1899 {
1900 public:
1901   Target_selector_i386()
1902     : Target_selector(elfcpp::EM_386, 32, false)
1903   { }
1904
1905   Target*
1906   recognize(int machine, int osabi, int abiversion);
1907
1908  private:
1909   Target_i386* target_;
1910 };
1911
1912 // Recognize an i386 object file when we already know that the machine
1913 // number is EM_386.
1914
1915 Target*
1916 Target_selector_i386::recognize(int, int, int)
1917 {
1918   if (this->target_ == NULL)
1919     this->target_ = new Target_i386();
1920   return this->target_;
1921 }
1922
1923 Target_selector_i386 target_selector_i386;
1924
1925 } // End anonymous namespace.