gold/i386.cc

   1 // i386.cc -- i386 target support for gold.
   2
   3 // Copyright 2006, 2007 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #include "gold.h"
  24
  25 #include <cstring>
  26
  27 #include "elfcpp.h"
  28 #include "parameters.h"
  29 #include "reloc.h"
  30 #include "i386.h"
  31 #include "object.h"
  32 #include "symtab.h"
  33 #include "layout.h"
  34 #include "output.h"
  35 #include "target.h"
  36 #include "target-reloc.h"
  37 #include "target-select.h"
  38 #include "tls.h"
  39
  40 namespace
  41 {
  42
  43 using namespace gold;
  44
  45 class Output_data_plt_i386;
  46
  47 // The i386 target class.
  48 // TLS info comes from
  49 //   http://people.redhat.com/drepper/tls.pdf
  50 //   http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
  51
  52 class Target_i386 : public Sized_target<32, false>
  53 {
  54  public:
  55   typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
  56
  57   Target_i386()
  58     : Sized_target<32, false>(&i386_info),
  59       got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
  60       copy_relocs_(NULL), dynbss_(NULL)
  61   { }
  62
  63   // Scan the relocations to look for symbol adjustments.
  64   void
  65   scan_relocs(const General_options& options,
  66               Symbol_table* symtab,
  67               Layout* layout,
  68               Sized_relobj<32, false>* object,
  69               unsigned int data_shndx,
  70               unsigned int sh_type,
  71               const unsigned char* prelocs,
  72               size_t reloc_count,
  73               size_t local_symbol_count,
  74               const unsigned char* plocal_symbols,
  75               Symbol** global_symbols);
  76
  77   // Finalize the sections.
  78   void
  79   do_finalize_sections(Layout*);
  80
  81   // Return the value to use for a dynamic which requires special
  82   // treatment.
  83   uint64_t
  84   do_dynsym_value(const Symbol*) const;
  85
  86   // Relocate a section.
  87   void
  88   relocate_section(const Relocate_info<32, false>*,
  89                    unsigned int sh_type,
  90                    const unsigned char* prelocs,
  91                    size_t reloc_count,
  92                    unsigned char* view,
  93                    elfcpp::Elf_types<32>::Elf_Addr view_address,
  94                    off_t view_size);
  95
  96   // Return a string used to fill a code section with nops.
  97   std::string
  98   do_code_fill(off_t length);
  99
 100  private:
 101   // The class which scans relocations.
 102   struct Scan
 103   {
 104     inline void
 105     local(const General_options& options, Symbol_table* symtab,
 106           Layout* layout, Target_i386* target,
 107           Sized_relobj<32, false>* object,
 108           unsigned int data_shndx,
 109           const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
 110           const elfcpp::Sym<32, false>& lsym);
 111
 112     inline void
 113     global(const General_options& options, Symbol_table* symtab,
 114            Layout* layout, Target_i386* target,
 115            Sized_relobj<32, false>* object,
 116            unsigned int data_shndx,
 117            const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
 118            Symbol* gsym);
 119
 120     static void
 121     unsupported_reloc_local(Sized_relobj<32, false>*, unsigned int r_type);
 122
 123     static void
 124     unsupported_reloc_global(Sized_relobj<32, false>*, unsigned int r_type,
 125                              Symbol*);
 126   };
 127
 128   // The class which implements relocation.
 129   class Relocate
 130   {
 131    public:
 132     Relocate()
 133       : skip_call_tls_get_addr_(false),
 134         local_dynamic_type_(LOCAL_DYNAMIC_NONE)
 135     { }
 136
 137     ~Relocate()
 138     {
 139       if (this->skip_call_tls_get_addr_)
 140         {
 141           // FIXME: This needs to specify the location somehow.
 142           gold_error(_("missing expected TLS relocation"));
 143         }
 144     }
 145
 146     // Do a relocation.  Return false if the caller should not issue
 147     // any warnings about this relocation.
 148     inline bool
 149     relocate(const Relocate_info<32, false>*, Target_i386*, size_t relnum,
 150              const elfcpp::Rel<32, false>&,
 151              unsigned int r_type, const Sized_symbol<32>*,
 152              const Symbol_value<32>*,
 153              unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
 154              off_t);
 155
 156    private:
 157     // Do a TLS relocation.
 158     inline void
 159     relocate_tls(const Relocate_info<32, false>*, size_t relnum,
 160                  const elfcpp::Rel<32, false>&,
 161                  unsigned int r_type, const Sized_symbol<32>*,
 162                  const Symbol_value<32>*,
 163                  unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, off_t);
 164
 165     // Do a TLS Initial-Exec to Local-Exec transition.
 166     static inline void
 167     tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum,
 168                  Output_segment* tls_segment,
 169                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 170                  elfcpp::Elf_types<32>::Elf_Addr value,
 171                  unsigned char* view,
 172                  off_t view_size);
 173
 174     // Do a TLS General-Dynamic to Local-Exec transition.
 175     inline void
 176     tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
 177                  Output_segment* tls_segment,
 178                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 179                  elfcpp::Elf_types<32>::Elf_Addr value,
 180                  unsigned char* view,
 181                  off_t view_size);
 182
 183     // Do a TLS Local-Dynamic to Local-Exec transition.
 184     inline void
 185     tls_ld_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     // We need to keep track of which type of local dynamic relocation
 193     // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
 194     enum Local_dynamic_type
 195     {
 196       LOCAL_DYNAMIC_NONE,
 197       LOCAL_DYNAMIC_SUN,
 198       LOCAL_DYNAMIC_GNU
 199     };
 200
 201     // This is set if we should skip the next reloc, which should be a
 202     // PLT32 reloc against ___tls_get_addr.
 203     bool skip_call_tls_get_addr_;
 204     // The type of local dynamic relocation we have seen in the section
 205     // being relocated, if any.
 206     Local_dynamic_type local_dynamic_type_;
 207   };
 208
 209   // Adjust TLS relocation type based on the options and whether this
 210   // is a local symbol.
 211   static tls::Tls_optimization
 212   optimize_tls_reloc(bool is_final, int r_type);
 213
 214   // Get the GOT section, creating it if necessary.
 215   Output_data_got<32, false>*
 216   got_section(Symbol_table*, Layout*);
 217
 218   // Create a PLT entry for a global symbol.
 219   void
 220   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 221
 222   // Get the PLT section.
 223   const Output_data_plt_i386*
 224   plt_section() const
 225   {
 226     gold_assert(this->plt_ != NULL);
 227     return this->plt_;
 228   }
 229
 230   // Get the dynamic reloc section, creating it if necessary.
 231   Reloc_section*
 232   rel_dyn_section(Layout*);
 233
 234   // Copy a relocation against a global symbol.
 235   void
 236   copy_reloc(const General_options*, Symbol_table*, Layout*,
 237              Sized_relobj<32, false>*, unsigned int,
 238              Symbol*, const elfcpp::Rel<32, false>&);
 239
 240   // Information about this specific target which we pass to the
 241   // general Target structure.
 242   static const Target::Target_info i386_info;
 243
 244   // The GOT section.
 245   Output_data_got<32, false>* got_;
 246   // The PLT section.
 247   Output_data_plt_i386* plt_;
 248   // The GOT PLT section.
 249   Output_data_space* got_plt_;
 250   // The dynamic reloc section.
 251   Reloc_section* rel_dyn_;
 252   // Relocs saved to avoid a COPY reloc.
 253   Copy_relocs<32, false>* copy_relocs_;
 254   // Space for variables copied with a COPY reloc.
 255   Output_data_space* dynbss_;
 256 };
 257
 258 const Target::Target_info Target_i386::i386_info =
 259 {
 260   32,                   // size
 261   false,                // is_big_endian
 262   elfcpp::EM_386,       // machine_code
 263   false,                // has_make_symbol
 264   false,                // has_resolve
 265   true,                 // has_code_fill
 266   "/usr/lib/libc.so.1", // dynamic_linker
 267   0x08048000,           // text_segment_address
 268   0x1000,               // abi_pagesize
 269   0x1000                // common_pagesize
 270 };
 271
 272 // Get the GOT section, creating it if necessary.
 273
 274 Output_data_got<32, false>*
 275 Target_i386::got_section(Symbol_table* symtab, Layout* layout)
 276 {
 277   if (this->got_ == NULL)
 278     {
 279       gold_assert(symtab != NULL && layout != NULL);
 280
 281       this->got_ = new Output_data_got<32, false>();
 282
 283       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 284                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 285                                       this->got_);
 286
 287       // The old GNU linker creates a .got.plt section.  We just
 288       // create another set of data in the .got section.  Note that we
 289       // always create a PLT if we create a GOT, although the PLT
 290       // might be empty.
 291       this->got_plt_ = new Output_data_space(4);
 292       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 293                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 294                                       this->got_plt_);
 295
 296       // The first three entries are reserved.
 297       this->got_plt_->set_space_size(3 * 4);
 298
 299       // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
 300       symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
 301                                     this->got_plt_,
 302                                     0, 0, elfcpp::STT_OBJECT,
 303                                     elfcpp::STB_LOCAL,
 304                                     elfcpp::STV_HIDDEN, 0,
 305                                     false, false);
 306     }
 307
 308   return this->got_;
 309 }
 310
 311 // Get the dynamic reloc section, creating it if necessary.
 312
 313 Target_i386::Reloc_section*
 314 Target_i386::rel_dyn_section(Layout* layout)
 315 {
 316   if (this->rel_dyn_ == NULL)
 317     {
 318       gold_assert(layout != NULL);
 319       this->rel_dyn_ = new Reloc_section();
 320       layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
 321                                       elfcpp::SHF_ALLOC, this->rel_dyn_);
 322     }
 323   return this->rel_dyn_;
 324 }
 325
 326 // A class to handle the PLT data.
 327
 328 class Output_data_plt_i386 : public Output_section_data
 329 {
 330  public:
 331   typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
 332
 333   Output_data_plt_i386(Layout*, Output_data_space*);
 334
 335   // Add an entry to the PLT.
 336   void
 337   add_entry(Symbol* gsym);
 338
 339   // Return the .rel.plt section data.
 340   const Reloc_section*
 341   rel_plt() const
 342   { return this->rel_; }
 343
 344  protected:
 345   void
 346   do_adjust_output_section(Output_section* os);
 347
 348  private:
 349   // The size of an entry in the PLT.
 350   static const int plt_entry_size = 16;
 351
 352   // The first entry in the PLT for an executable.
 353   static unsigned char exec_first_plt_entry[plt_entry_size];
 354
 355   // The first entry in the PLT for a shared object.
 356   static unsigned char dyn_first_plt_entry[plt_entry_size];
 357
 358   // Other entries in the PLT for an executable.
 359   static unsigned char exec_plt_entry[plt_entry_size];
 360
 361   // Other entries in the PLT for a shared object.
 362   static unsigned char dyn_plt_entry[plt_entry_size];
 363
 364   // Set the final size.
 365   void
 366   do_set_address(uint64_t, off_t)
 367   { this->set_data_size((this->count_ + 1) * plt_entry_size); }
 368
 369   // Write out the PLT data.
 370   void
 371   do_write(Output_file*);
 372
 373   // The reloc section.
 374   Reloc_section* rel_;
 375   // The .got.plt section.
 376   Output_data_space* got_plt_;
 377   // The number of PLT entries.
 378   unsigned int count_;
 379 };
 380
 381 // Create the PLT section.  The ordinary .got section is an argument,
 382 // since we need to refer to the start.  We also create our own .got
 383 // section just for PLT entries.
 384
 385 Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
 386                                            Output_data_space* got_plt)
 387   : Output_section_data(4), got_plt_(got_plt), count_(0)
 388 {
 389   this->rel_ = new Reloc_section();
 390   layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
 391                                   elfcpp::SHF_ALLOC, this->rel_);
 392 }
 393
 394 void
 395 Output_data_plt_i386::do_adjust_output_section(Output_section* os)
 396 {
 397   // UnixWare sets the entsize of .plt to 4, and so does the old GNU
 398   // linker, and so do we.
 399   os->set_entsize(4);
 400 }
 401
 402 // Add an entry to the PLT.
 403
 404 void
 405 Output_data_plt_i386::add_entry(Symbol* gsym)
 406 {
 407   gold_assert(!gsym->has_plt_offset());
 408
 409   // Note that when setting the PLT offset we skip the initial
 410   // reserved PLT entry.
 411   gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
 412
 413   ++this->count_;
 414
 415   off_t got_offset = this->got_plt_->data_size();
 416
 417   // Every PLT entry needs a GOT entry which points back to the PLT
 418   // entry (this will be changed by the dynamic linker, normally
 419   // lazily when the function is called).
 420   this->got_plt_->set_space_size(got_offset + 4);
 421
 422   // Every PLT entry needs a reloc.
 423   gsym->set_needs_dynsym_entry();
 424   this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_,
 425                          got_offset);
 426
 427   // Note that we don't need to save the symbol.  The contents of the
 428   // PLT are independent of which symbols are used.  The symbols only
 429   // appear in the relocations.
 430 }
 431
 432 // The first entry in the PLT for an executable.
 433
 434 unsigned char Output_data_plt_i386::exec_first_plt_entry[plt_entry_size] =
 435 {
 436   0xff, 0x35,   // pushl contents of memory address
 437   0, 0, 0, 0,   // replaced with address of .got + 4
 438   0xff, 0x25,   // jmp indirect
 439   0, 0, 0, 0,   // replaced with address of .got + 8
 440   0, 0, 0, 0    // unused
 441 };
 442
 443 // The first entry in the PLT for a shared object.
 444
 445 unsigned char Output_data_plt_i386::dyn_first_plt_entry[plt_entry_size] =
 446 {
 447   0xff, 0xb3, 4, 0, 0, 0,       // pushl 4(%ebx)
 448   0xff, 0xa3, 8, 0, 0, 0,       // jmp *8(%ebx)
 449   0, 0, 0, 0                    // unused
 450 };
 451
 452 // Subsequent entries in the PLT for an executable.
 453
 454 unsigned char Output_data_plt_i386::exec_plt_entry[plt_entry_size] =
 455 {
 456   0xff, 0x25,   // jmp indirect
 457   0, 0, 0, 0,   // replaced with address of symbol in .got
 458   0x68,         // pushl immediate
 459   0, 0, 0, 0,   // replaced with offset into relocation table
 460   0xe9,         // jmp relative
 461   0, 0, 0, 0    // replaced with offset to start of .plt
 462 };
 463
 464 // Subsequent entries in the PLT for a shared object.
 465
 466 unsigned char Output_data_plt_i386::dyn_plt_entry[plt_entry_size] =
 467 {
 468   0xff, 0xa3,   // jmp *offset(%ebx)
 469   0, 0, 0, 0,   // replaced with offset of symbol in .got
 470   0x68,         // pushl immediate
 471   0, 0, 0, 0,   // replaced with offset into relocation table
 472   0xe9,         // jmp relative
 473   0, 0, 0, 0    // replaced with offset to start of .plt
 474 };
 475
 476 // Write out the PLT.  This uses the hand-coded instructions above,
 477 // and adjusts them as needed.  This is all specified by the i386 ELF
 478 // Processor Supplement.
 479
 480 void
 481 Output_data_plt_i386::do_write(Output_file* of)
 482 {
 483   const off_t offset = this->offset();
 484   const off_t oview_size = this->data_size();
 485   unsigned char* const oview = of->get_output_view(offset, oview_size);
 486
 487   const off_t got_file_offset = this->got_plt_->offset();
 488   const off_t got_size = this->got_plt_->data_size();
 489   unsigned char* const got_view = of->get_output_view(got_file_offset,
 490                                                       got_size);
 491
 492   unsigned char* pov = oview;
 493
 494   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
 495   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 496
 497   if (parameters->output_is_shared())
 498     memcpy(pov, dyn_first_plt_entry, plt_entry_size);
 499   else
 500     {
 501       memcpy(pov, exec_first_plt_entry, plt_entry_size);
 502       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
 503       elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
 504     }
 505   pov += plt_entry_size;
 506
 507   unsigned char* got_pov = got_view;
 508
 509   memset(got_pov, 0, 12);
 510   got_pov += 12;
 511
 512   const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
 513
 514   unsigned int plt_offset = plt_entry_size;
 515   unsigned int plt_rel_offset = 0;
 516   unsigned int got_offset = 12;
 517   const unsigned int count = this->count_;
 518   for (unsigned int i = 0;
 519        i < count;
 520        ++i,
 521          pov += plt_entry_size,
 522          got_pov += 4,
 523          plt_offset += plt_entry_size,
 524          plt_rel_offset += rel_size,
 525          got_offset += 4)
 526     {
 527       // Set and adjust the PLT entry itself.
 528
 529       if (parameters->output_is_shared())
 530         {
 531           memcpy(pov, dyn_plt_entry, plt_entry_size);
 532           elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
 533         }
 534       else
 535         {
 536           memcpy(pov, exec_plt_entry, plt_entry_size);
 537           elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 538                                                       (got_address
 539                                                        + got_offset));
 540         }
 541
 542       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
 543       elfcpp::Swap<32, false>::writeval(pov + 12,
 544                                         - (plt_offset + plt_entry_size));
 545
 546       // Set the entry in the GOT.
 547       elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6);
 548     }
 549
 550   gold_assert(pov - oview == oview_size);
 551   gold_assert(got_pov - got_view == got_size);
 552
 553   of->write_output_view(offset, oview_size, oview);
 554   of->write_output_view(got_file_offset, got_size, got_view);
 555 }
 556
 557 // Create a PLT entry for a global symbol.
 558
 559 void
 560 Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym)
 561 {
 562   if (gsym->has_plt_offset())
 563     return;
 564
 565   if (this->plt_ == NULL)
 566     {
 567       // Create the GOT sections first.
 568       this->got_section(symtab, layout);
 569
 570       this->plt_ = new Output_data_plt_i386(layout, this->got_plt_);
 571       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 572                                       (elfcpp::SHF_ALLOC
 573                                        | elfcpp::SHF_EXECINSTR),
 574                                       this->plt_);
 575     }
 576
 577   this->plt_->add_entry(gsym);
 578 }
 579
 580 // Handle a relocation against a non-function symbol defined in a
 581 // dynamic object.  The traditional way to handle this is to generate
 582 // a COPY relocation to copy the variable at runtime from the shared
 583 // object into the executable's data segment.  However, this is
 584 // undesirable in general, as if the size of the object changes in the
 585 // dynamic object, the executable will no longer work correctly.  If
 586 // this relocation is in a writable section, then we can create a
 587 // dynamic reloc and the dynamic linker will resolve it to the correct
 588 // address at runtime.  However, we do not want do that if the
 589 // relocation is in a read-only section, as it would prevent the
 590 // readonly segment from being shared.  And if we have to eventually
 591 // generate a COPY reloc, then any dynamic relocations will be
 592 // useless.  So this means that if this is a writable section, we need
 593 // to save the relocation until we see whether we have to create a
 594 // COPY relocation for this symbol for any other relocation.
 595
 596 void
 597 Target_i386::copy_reloc(const General_options* options,
 598                         Symbol_table* symtab,
 599                         Layout* layout,
 600                         Sized_relobj<32, false>* object,
 601                         unsigned int data_shndx, Symbol* gsym,
 602                         const elfcpp::Rel<32, false>& rel)
 603 {
 604   Sized_symbol<32>* ssym;
 605   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(32) (gsym
 606                                                         SELECT_SIZE(32));
 607
 608   if (!Copy_relocs<32, false>::need_copy_reloc(options, object,
 609                                                data_shndx, ssym))
 610     {
 611       // So far we do not need a COPY reloc.  Save this relocation.
 612       // If it turns out that we never need a COPY reloc for this
 613       // symbol, then we will emit the relocation.
 614       if (this->copy_relocs_ == NULL)
 615         this->copy_relocs_ = new Copy_relocs<32, false>();
 616       this->copy_relocs_->save(ssym, object, data_shndx, rel);
 617     }
 618   else
 619     {
 620       // Allocate space for this symbol in the .bss section.
 621
 622       elfcpp::Elf_types<32>::Elf_WXword symsize = ssym->symsize();
 623
 624       // There is no defined way to determine the required alignment
 625       // of the symbol.  We pick the alignment based on the size.  We
 626       // set an arbitrary maximum of 256.
 627       unsigned int align;
 628       for (align = 1; align < 512; align <<= 1)
 629         if ((symsize & align) != 0)
 630           break;
 631
 632       if (this->dynbss_ == NULL)
 633         {
 634           this->dynbss_ = new Output_data_space(align);
 635           layout->add_output_section_data(".bss",
 636                                           elfcpp::SHT_NOBITS,
 637                                           (elfcpp::SHF_ALLOC
 638                                            | elfcpp::SHF_WRITE),
 639                                           this->dynbss_);
 640         }
 641
 642       Output_data_space* dynbss = this->dynbss_;
 643
 644       if (align > dynbss->addralign())
 645         dynbss->set_space_alignment(align);
 646
 647       off_t dynbss_size = dynbss->data_size();
 648       dynbss_size = align_address(dynbss_size, align);
 649       off_t offset = dynbss_size;
 650       dynbss->set_space_size(dynbss_size + symsize);
 651
 652       // Define the symbol in the .dynbss section.
 653       symtab->define_in_output_data(this, ssym->name(), ssym->version(),
 654                                     dynbss, offset, symsize, ssym->type(),
 655                                     ssym->binding(), ssym->visibility(),
 656                                     ssym->nonvis(), false, false);
 657
 658       // Add the COPY reloc.
 659       ssym->set_needs_dynsym_entry();
 660       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
 661       rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset);
 662     }
 663 }
 664
 665 // Optimize the TLS relocation type based on what we know about the
 666 // symbol.  IS_FINAL is true if the final address of this symbol is
 667 // known at link time.
 668
 669 tls::Tls_optimization
 670 Target_i386::optimize_tls_reloc(bool is_final, int r_type)
 671 {
 672   // If we are generating a shared library, then we can't do anything
 673   // in the linker.
 674   if (parameters->output_is_shared())
 675     return tls::TLSOPT_NONE;
 676
 677   switch (r_type)
 678     {
 679     case elfcpp::R_386_TLS_GD:
 680     case elfcpp::R_386_TLS_GOTDESC:
 681     case elfcpp::R_386_TLS_DESC_CALL:
 682       // These are General-Dynamic which permits fully general TLS
 683       // access.  Since we know that we are generating an executable,
 684       // we can convert this to Initial-Exec.  If we also know that
 685       // this is a local symbol, we can further switch to Local-Exec.
 686       if (is_final)
 687         return tls::TLSOPT_TO_LE;
 688       return tls::TLSOPT_TO_IE;
 689
 690     case elfcpp::R_386_TLS_LDM:
 691       // This is Local-Dynamic, which refers to a local symbol in the
 692       // dynamic TLS block.  Since we know that we generating an
 693       // executable, we can switch to Local-Exec.
 694       return tls::TLSOPT_TO_LE;
 695
 696     case elfcpp::R_386_TLS_LDO_32:
 697       // Another type of Local-Dynamic relocation.
 698       return tls::TLSOPT_TO_LE;
 699
 700     case elfcpp::R_386_TLS_IE:
 701     case elfcpp::R_386_TLS_GOTIE:
 702     case elfcpp::R_386_TLS_IE_32:
 703       // These are Initial-Exec relocs which get the thread offset
 704       // from the GOT.  If we know that we are linking against the
 705       // local symbol, we can switch to Local-Exec, which links the
 706       // thread offset into the instruction.
 707       if (is_final)
 708         return tls::TLSOPT_TO_LE;
 709       return tls::TLSOPT_NONE;
 710
 711     case elfcpp::R_386_TLS_LE:
 712     case elfcpp::R_386_TLS_LE_32:
 713       // When we already have Local-Exec, there is nothing further we
 714       // can do.
 715       return tls::TLSOPT_NONE;
 716
 717     default:
 718       gold_unreachable();
 719     }
 720 }
 721
 722 // Report an unsupported relocation against a local symbol.
 723
 724 void
 725 Target_i386::Scan::unsupported_reloc_local(Sized_relobj<32, false>* object,
 726                                            unsigned int r_type)
 727 {
 728   gold_error(_("%s: unsupported reloc %u against local symbol"),
 729              object->name().c_str(), r_type);
 730 }
 731
 732 // Scan a relocation for a local symbol.
 733
 734 inline void
 735 Target_i386::Scan::local(const General_options&,
 736                          Symbol_table* symtab,
 737                          Layout* layout,
 738                          Target_i386* target,
 739                          Sized_relobj<32, false>* object,
 740                          unsigned int,
 741                          const elfcpp::Rel<32, false>&,
 742                          unsigned int r_type,
 743                          const elfcpp::Sym<32, false>&)
 744 {
 745   switch (r_type)
 746     {
 747     case elfcpp::R_386_NONE:
 748     case elfcpp::R_386_GNU_VTINHERIT:
 749     case elfcpp::R_386_GNU_VTENTRY:
 750       break;
 751
 752     case elfcpp::R_386_32:
 753     case elfcpp::R_386_16:
 754     case elfcpp::R_386_8:
 755       // FIXME: If we are generating a shared object we need to copy
 756       // this relocation into the object.
 757       gold_assert(!parameters->output_is_shared());
 758       break;
 759
 760     case elfcpp::R_386_PC32:
 761     case elfcpp::R_386_PC16:
 762     case elfcpp::R_386_PC8:
 763       break;
 764
 765     case elfcpp::R_386_GOTOFF:
 766     case elfcpp::R_386_GOTPC:
 767       // We need a GOT section.
 768       target->got_section(symtab, layout);
 769       break;
 770
 771       // These are relocations which should only be seen by the
 772       // dynamic linker, and should never be seen here.
 773     case elfcpp::R_386_COPY:
 774     case elfcpp::R_386_GLOB_DAT:
 775     case elfcpp::R_386_JUMP_SLOT:
 776     case elfcpp::R_386_RELATIVE:
 777     case elfcpp::R_386_TLS_TPOFF:
 778     case elfcpp::R_386_TLS_DTPMOD32:
 779     case elfcpp::R_386_TLS_DTPOFF32:
 780     case elfcpp::R_386_TLS_TPOFF32:
 781     case elfcpp::R_386_TLS_DESC:
 782       gold_error(_("%s: unexpected reloc %u in object file\n"),
 783                  object->name().c_str(), r_type);
 784       break;
 785
 786       // These are initial TLS relocs, which are expected when
 787       // linking.
 788     case elfcpp::R_386_TLS_IE:
 789     case elfcpp::R_386_TLS_GOTIE:
 790     case elfcpp::R_386_TLS_LE:
 791     case elfcpp::R_386_TLS_GD:
 792     case elfcpp::R_386_TLS_LDM:
 793     case elfcpp::R_386_TLS_LDO_32:
 794     case elfcpp::R_386_TLS_IE_32:
 795     case elfcpp::R_386_TLS_LE_32:
 796     case elfcpp::R_386_TLS_GOTDESC:
 797     case elfcpp::R_386_TLS_DESC_CALL:
 798       {
 799         bool output_is_shared = parameters->output_is_shared();
 800         const tls::Tls_optimization optimized_type
 801             = Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
 802         switch (r_type)
 803           {
 804           case elfcpp::R_386_TLS_LE:
 805           case elfcpp::R_386_TLS_LE_32:
 806             // FIXME: If generating a shared object, we need to copy
 807             // this relocation into the object.
 808             gold_assert(!output_is_shared);
 809             break;
 810
 811           case elfcpp::R_386_TLS_IE:
 812           case elfcpp::R_386_TLS_IE_32:
 813           case elfcpp::R_386_TLS_GOTIE:
 814             // FIXME: If not relaxing to LE, we need to generate a
 815             // TPOFF or TPOFF32 reloc.
 816             if (optimized_type != tls::TLSOPT_TO_LE)
 817               unsupported_reloc_local(object, r_type);
 818             break;
 819
 820           case elfcpp::R_386_TLS_LDM:
 821             // FIXME: If not relaxing to LE, we need to generate a
 822             // DTPMOD32 reloc.
 823             if (optimized_type != tls::TLSOPT_TO_LE)
 824               unsupported_reloc_local(object, r_type);
 825             break;
 826
 827           case elfcpp::R_386_TLS_LDO_32:
 828             break;
 829
 830           case elfcpp::R_386_TLS_GD:
 831           case elfcpp::R_386_TLS_GOTDESC:
 832           case elfcpp::R_386_TLS_DESC_CALL:
 833             // FIXME: If not relaxing to LE, we need to generate
 834             // DTPMOD32 and DTPOFF32 relocs.
 835             if (optimized_type != tls::TLSOPT_TO_LE)
 836               unsupported_reloc_local(object, r_type);
 837             break;
 838
 839           default:
 840             gold_unreachable();
 841           }
 842       }
 843       break;
 844
 845     case elfcpp::R_386_GOT32:
 846     case elfcpp::R_386_PLT32:
 847     case elfcpp::R_386_32PLT:
 848     case elfcpp::R_386_TLS_GD_32:
 849     case elfcpp::R_386_TLS_GD_PUSH:
 850     case elfcpp::R_386_TLS_GD_CALL:
 851     case elfcpp::R_386_TLS_GD_POP:
 852     case elfcpp::R_386_TLS_LDM_32:
 853     case elfcpp::R_386_TLS_LDM_PUSH:
 854     case elfcpp::R_386_TLS_LDM_CALL:
 855     case elfcpp::R_386_TLS_LDM_POP:
 856     case elfcpp::R_386_USED_BY_INTEL_200:
 857     default:
 858       unsupported_reloc_local(object, r_type);
 859       break;
 860     }
 861 }
 862
 863 // Report an unsupported relocation against a global symbol.
 864
 865 void
 866 Target_i386::Scan::unsupported_reloc_global(Sized_relobj<32, false>* object,
 867                                             unsigned int r_type,
 868                                             Symbol* gsym)
 869 {
 870   gold_error(_("%s: unsupported reloc %u against global symbol %s"),
 871              object->name().c_str(), r_type, gsym->name());
 872 }
 873
 874 // Scan a relocation for a global symbol.
 875
 876 inline void
 877 Target_i386::Scan::global(const General_options& options,
 878                           Symbol_table* symtab,
 879                           Layout* layout,
 880                           Target_i386* target,
 881                           Sized_relobj<32, false>* object,
 882                           unsigned int data_shndx,
 883                           const elfcpp::Rel<32, false>& reloc,
 884                           unsigned int r_type,
 885                           Symbol* gsym)
 886 {
 887   switch (r_type)
 888     {
 889     case elfcpp::R_386_NONE:
 890     case elfcpp::R_386_GNU_VTINHERIT:
 891     case elfcpp::R_386_GNU_VTENTRY:
 892       break;
 893
 894     case elfcpp::R_386_32:
 895     case elfcpp::R_386_PC32:
 896     case elfcpp::R_386_16:
 897     case elfcpp::R_386_PC16:
 898     case elfcpp::R_386_8:
 899     case elfcpp::R_386_PC8:
 900       // FIXME: If we are generating a shared object we may need to
 901       // copy this relocation into the object.  If this symbol is
 902       // defined in a shared object, we may need to copy this
 903       // relocation in order to avoid a COPY relocation.
 904       gold_assert(!parameters->output_is_shared());
 905
 906       if (gsym->is_from_dynobj())
 907         {
 908           // This symbol is defined in a dynamic object.  If it is a
 909           // function, we make a PLT entry.  Otherwise we need to
 910           // either generate a COPY reloc or copy this reloc.
 911           if (gsym->type() == elfcpp::STT_FUNC)
 912             {
 913               target->make_plt_entry(symtab, layout, gsym);
 914
 915               // If this is not a PC relative reference, then we may
 916               // be taking the address of the function.  In that case
 917               // we need to set the entry in the dynamic symbol table
 918               // to the address of the PLT entry.
 919               if (r_type != elfcpp::R_386_PC32
 920                   && r_type != elfcpp::R_386_PC16
 921                   && r_type != elfcpp::R_386_PC8)
 922                 gsym->set_needs_dynsym_value();
 923             }
 924           else
 925             target->copy_reloc(&options, symtab, layout, object, data_shndx,
 926                                gsym, reloc);
 927         }
 928
 929       break;
 930
 931     case elfcpp::R_386_GOT32:
 932       {
 933         // The symbol requires a GOT entry.
 934         Output_data_got<32, false>* got = target->got_section(symtab, layout);
 935         if (got->add_global(gsym))
 936           {
 937             // If this symbol is not fully resolved, we need to add a
 938             // dynamic relocation for it.
 939             if (!gsym->final_value_is_known())
 940               {
 941                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 942                 rel_dyn->add_global(gsym, elfcpp::R_386_GLOB_DAT, got,
 943                                     gsym->got_offset());
 944               }
 945           }
 946       }
 947       break;
 948
 949     case elfcpp::R_386_PLT32:
 950       // If the symbol is fully resolved, this is just a PC32 reloc.
 951       // Otherwise we need a PLT entry.
 952       if (gsym->final_value_is_known())
 953         break;
 954       target->make_plt_entry(symtab, layout, gsym);
 955       break;
 956
 957     case elfcpp::R_386_GOTOFF:
 958     case elfcpp::R_386_GOTPC:
 959       // We need a GOT section.
 960       target->got_section(symtab, layout);
 961       break;
 962
 963       // These are relocations which should only be seen by the
 964       // dynamic linker, and should never be seen here.
 965     case elfcpp::R_386_COPY:
 966     case elfcpp::R_386_GLOB_DAT:
 967     case elfcpp::R_386_JUMP_SLOT:
 968     case elfcpp::R_386_RELATIVE:
 969     case elfcpp::R_386_TLS_TPOFF:
 970     case elfcpp::R_386_TLS_DTPMOD32:
 971     case elfcpp::R_386_TLS_DTPOFF32:
 972     case elfcpp::R_386_TLS_TPOFF32:
 973     case elfcpp::R_386_TLS_DESC:
 974       gold_error(_("%s: unexpected reloc %u in object file"),
 975                  object->name().c_str(), r_type);
 976       break;
 977
 978       // These are initial tls relocs, which are expected when
 979       // linking.
 980     case elfcpp::R_386_TLS_IE:
 981     case elfcpp::R_386_TLS_GOTIE:
 982     case elfcpp::R_386_TLS_LE:
 983     case elfcpp::R_386_TLS_GD:
 984     case elfcpp::R_386_TLS_LDM:
 985     case elfcpp::R_386_TLS_LDO_32:
 986     case elfcpp::R_386_TLS_IE_32:
 987     case elfcpp::R_386_TLS_LE_32:
 988     case elfcpp::R_386_TLS_GOTDESC:
 989     case elfcpp::R_386_TLS_DESC_CALL:
 990       {
 991         const bool is_final = gsym->final_value_is_known();
 992         const tls::Tls_optimization optimized_type
 993             = Target_i386::optimize_tls_reloc(is_final, r_type);
 994         switch (r_type)
 995           {
 996           case elfcpp::R_386_TLS_LE:
 997           case elfcpp::R_386_TLS_LE_32:
 998             // FIXME: If generating a shared object, we need to copy
 999             // this relocation into the object.
1000             gold_assert(!parameters->output_is_shared());
1001             break;
1002
1003           case elfcpp::R_386_TLS_IE:
1004           case elfcpp::R_386_TLS_IE_32:
1005           case elfcpp::R_386_TLS_GOTIE:
1006             // FIXME: If not relaxing to LE, we need to generate a
1007             // TPOFF or TPOFF32 reloc.
1008             if (optimized_type != tls::TLSOPT_TO_LE)
1009               unsupported_reloc_global(object, r_type, gsym);
1010             break;
1011
1012           case elfcpp::R_386_TLS_LDM:
1013             // FIXME: If not relaxing to LE, we need to generate a
1014             // DTPMOD32 reloc.
1015             if (optimized_type != tls::TLSOPT_TO_LE)
1016               unsupported_reloc_global(object, r_type, gsym);
1017             break;
1018
1019           case elfcpp::R_386_TLS_LDO_32:
1020             break;
1021
1022           case elfcpp::R_386_TLS_GD:
1023           case elfcpp::R_386_TLS_GOTDESC:
1024           case elfcpp::R_386_TLS_DESC_CALL:
1025             // FIXME: If not relaxing to LE, we need to generate
1026             // DTPMOD32 and DTPOFF32 relocs.
1027             if (optimized_type != tls::TLSOPT_TO_LE)
1028               unsupported_reloc_global(object, r_type, gsym);
1029             break;
1030
1031           default:
1032             gold_unreachable();
1033           }
1034       }
1035       break;
1036
1037     case elfcpp::R_386_32PLT:
1038     case elfcpp::R_386_TLS_GD_32:
1039     case elfcpp::R_386_TLS_GD_PUSH:
1040     case elfcpp::R_386_TLS_GD_CALL:
1041     case elfcpp::R_386_TLS_GD_POP:
1042     case elfcpp::R_386_TLS_LDM_32:
1043     case elfcpp::R_386_TLS_LDM_PUSH:
1044     case elfcpp::R_386_TLS_LDM_CALL:
1045     case elfcpp::R_386_TLS_LDM_POP:
1046     case elfcpp::R_386_USED_BY_INTEL_200:
1047     default:
1048       unsupported_reloc_global(object, r_type, gsym);
1049       break;
1050     }
1051 }
1052
1053 // Scan relocations for a section.
1054
1055 void
1056 Target_i386::scan_relocs(const General_options& options,
1057                          Symbol_table* symtab,
1058                          Layout* layout,
1059                          Sized_relobj<32, false>* object,
1060                          unsigned int data_shndx,
1061                          unsigned int sh_type,
1062                          const unsigned char* prelocs,
1063                          size_t reloc_count,
1064                          size_t local_symbol_count,
1065                          const unsigned char* plocal_symbols,
1066                          Symbol** global_symbols)
1067 {
1068   if (sh_type == elfcpp::SHT_RELA)
1069     {
1070       gold_error(_("%s: unsupported RELA reloc section"),
1071                  object->name().c_str());
1072       return;
1073     }
1074
1075   gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
1076                     Target_i386::Scan>(
1077     options,
1078     symtab,
1079     layout,
1080     this,
1081     object,
1082     data_shndx,
1083     prelocs,
1084     reloc_count,
1085     local_symbol_count,
1086     plocal_symbols,
1087     global_symbols);
1088 }
1089
1090 // Finalize the sections.
1091
1092 void
1093 Target_i386::do_finalize_sections(Layout* layout)
1094 {
1095   // Fill in some more dynamic tags.
1096   Output_data_dynamic* const odyn = layout->dynamic_data();
1097   if (odyn != NULL)
1098     {
1099       if (this->got_plt_ != NULL)
1100         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1101
1102       if (this->plt_ != NULL)
1103         {
1104           const Output_data* od = this->plt_->rel_plt();
1105           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1106           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1107           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL);
1108         }
1109
1110       if (this->rel_dyn_ != NULL)
1111         {
1112           const Output_data* od = this->rel_dyn_;
1113           odyn->add_section_address(elfcpp::DT_REL, od);
1114           odyn->add_section_size(elfcpp::DT_RELSZ, od);
1115           odyn->add_constant(elfcpp::DT_RELENT,
1116                              elfcpp::Elf_sizes<32>::rel_size);
1117         }
1118
1119       if (!parameters->output_is_shared())
1120         {
1121           // The value of the DT_DEBUG tag is filled in by the dynamic
1122           // linker at run time, and used by the debugger.
1123           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1124         }
1125     }
1126
1127   // Emit any relocs we saved in an attempt to avoid generating COPY
1128   // relocs.
1129   if (this->copy_relocs_ == NULL)
1130     return;
1131   if (this->copy_relocs_->any_to_emit())
1132     {
1133       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1134       this->copy_relocs_->emit(rel_dyn);
1135     }
1136   delete this->copy_relocs_;
1137   this->copy_relocs_ = NULL;
1138 }
1139
1140 // Perform a relocation.
1141
1142 inline bool
1143 Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
1144                                 Target_i386* target,
1145                                 size_t relnum,
1146                                 const elfcpp::Rel<32, false>& rel,
1147                                 unsigned int r_type,
1148                                 const Sized_symbol<32>* gsym,
1149                                 const Symbol_value<32>* psymval,
1150                                 unsigned char* view,
1151                                 elfcpp::Elf_types<32>::Elf_Addr address,
1152                                 off_t view_size)
1153 {
1154   if (this->skip_call_tls_get_addr_)
1155     {
1156       if (r_type != elfcpp::R_386_PLT32
1157           || gsym == NULL
1158           || strcmp(gsym->name(), "___tls_get_addr") != 0)
1159         gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1160                                _("missing expected TLS relocation"));
1161       else
1162         {
1163           this->skip_call_tls_get_addr_ = false;
1164           return false;
1165         }
1166     }
1167
1168   // Pick the value to use for symbols defined in shared objects.
1169   Symbol_value<32> symval;
1170   if (gsym != NULL && gsym->is_from_dynobj() && gsym->has_plt_offset())
1171     {
1172       symval.set_output_value(target->plt_section()->address()
1173                               + gsym->plt_offset());
1174       psymval = &symval;
1175     }
1176
1177   const Sized_relobj<32, false>* object = relinfo->object;
1178
1179   switch (r_type)
1180     {
1181     case elfcpp::R_386_NONE:
1182     case elfcpp::R_386_GNU_VTINHERIT:
1183     case elfcpp::R_386_GNU_VTENTRY:
1184       break;
1185
1186     case elfcpp::R_386_32:
1187       Relocate_functions<32, false>::rel32(view, object, psymval);
1188       break;
1189
1190     case elfcpp::R_386_PC32:
1191       Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1192       break;
1193
1194     case elfcpp::R_386_16:
1195       Relocate_functions<32, false>::rel16(view, object, psymval);
1196       break;
1197
1198     case elfcpp::R_386_PC16:
1199       Relocate_functions<32, false>::pcrel16(view, object, psymval, address);
1200       break;
1201
1202     case elfcpp::R_386_8:
1203       Relocate_functions<32, false>::rel8(view, object, psymval);
1204       break;
1205
1206     case elfcpp::R_386_PC8:
1207       Relocate_functions<32, false>::pcrel8(view, object, psymval, address);
1208       break;
1209
1210     case elfcpp::R_386_PLT32:
1211       gold_assert(gsym->has_plt_offset()
1212                   || gsym->final_value_is_known());
1213       Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1214       break;
1215
1216     case elfcpp::R_386_GOT32:
1217       // Local GOT offsets not yet supported.
1218       gold_assert(gsym);
1219       gold_assert(gsym->has_got_offset());
1220       Relocate_functions<32, false>::rel32(view, gsym->got_offset());
1221       break;
1222
1223     case elfcpp::R_386_GOTOFF:
1224       {
1225         elfcpp::Elf_types<32>::Elf_Addr value;
1226         value = (psymval->value(object, 0)
1227                  - target->got_section(NULL, NULL)->address());
1228         Relocate_functions<32, false>::rel32(view, value);
1229       }
1230       break;
1231
1232     case elfcpp::R_386_GOTPC:
1233       {
1234         elfcpp::Elf_types<32>::Elf_Addr value;
1235         value = target->got_section(NULL, NULL)->address();
1236         Relocate_functions<32, false>::pcrel32(view, value, address);
1237       }
1238       break;
1239
1240     case elfcpp::R_386_COPY:
1241     case elfcpp::R_386_GLOB_DAT:
1242     case elfcpp::R_386_JUMP_SLOT:
1243     case elfcpp::R_386_RELATIVE:
1244       // These are outstanding tls relocs, which are unexpected when
1245       // linking.
1246     case elfcpp::R_386_TLS_TPOFF:
1247     case elfcpp::R_386_TLS_DTPMOD32:
1248     case elfcpp::R_386_TLS_DTPOFF32:
1249     case elfcpp::R_386_TLS_TPOFF32:
1250     case elfcpp::R_386_TLS_DESC:
1251       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1252                              _("unexpected reloc %u in object file"),
1253                              r_type);
1254       break;
1255
1256       // These are initial tls relocs, which are expected when
1257       // linking.
1258     case elfcpp::R_386_TLS_IE:
1259     case elfcpp::R_386_TLS_GOTIE:
1260     case elfcpp::R_386_TLS_LE:
1261     case elfcpp::R_386_TLS_GD:
1262     case elfcpp::R_386_TLS_LDM:
1263     case elfcpp::R_386_TLS_LDO_32:
1264     case elfcpp::R_386_TLS_IE_32:
1265     case elfcpp::R_386_TLS_LE_32:
1266     case elfcpp::R_386_TLS_GOTDESC:
1267     case elfcpp::R_386_TLS_DESC_CALL:
1268       this->relocate_tls(relinfo, relnum, rel, r_type, gsym, psymval, view,
1269                          address, view_size);
1270       break;
1271
1272     case elfcpp::R_386_32PLT:
1273     case elfcpp::R_386_TLS_GD_32:
1274     case elfcpp::R_386_TLS_GD_PUSH:
1275     case elfcpp::R_386_TLS_GD_CALL:
1276     case elfcpp::R_386_TLS_GD_POP:
1277     case elfcpp::R_386_TLS_LDM_32:
1278     case elfcpp::R_386_TLS_LDM_PUSH:
1279     case elfcpp::R_386_TLS_LDM_CALL:
1280     case elfcpp::R_386_TLS_LDM_POP:
1281     case elfcpp::R_386_USED_BY_INTEL_200:
1282     default:
1283       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1284                              _("unsupported reloc %u"),
1285                              r_type);
1286       break;
1287     }
1288
1289   return true;
1290 }
1291
1292 // Perform a TLS relocation.
1293
1294 inline void
1295 Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
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,
1303                                     off_t view_size)
1304 {
1305   Output_segment* tls_segment = relinfo->layout->tls_segment();
1306   if (tls_segment == NULL)
1307     {
1308       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1309                              _("TLS reloc but no TLS segment"));
1310       return;
1311     }
1312
1313   elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(relinfo->object, 0);
1314
1315   const bool is_final = (gsym == NULL
1316                          ? !parameters->output_is_shared()
1317                          : gsym->final_value_is_known());
1318   const tls::Tls_optimization optimized_type
1319       = Target_i386::optimize_tls_reloc(is_final, r_type);
1320   switch (r_type)
1321     {
1322     case elfcpp::R_386_TLS_LE_32:
1323       value = tls_segment->vaddr() + tls_segment->memsz() - value;
1324       Relocate_functions<32, false>::rel32(view, value);
1325       break;
1326
1327     case elfcpp::R_386_TLS_LE:
1328       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1329       Relocate_functions<32, false>::rel32(view, value);
1330       break;
1331
1332     case elfcpp::R_386_TLS_IE:
1333     case elfcpp::R_386_TLS_GOTIE:
1334     case elfcpp::R_386_TLS_IE_32:
1335       if (optimized_type == tls::TLSOPT_TO_LE)
1336         {
1337           Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1338                                               rel, r_type, value, view,
1339                                               view_size);
1340           break;
1341         }
1342       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1343                              _("unsupported reloc %u"),
1344                              r_type);
1345       break;
1346
1347     case elfcpp::R_386_TLS_GD:
1348       if (optimized_type == tls::TLSOPT_TO_LE)
1349         {
1350           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1351                              rel, r_type, value, view,
1352                              view_size);
1353           break;
1354         }
1355       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1356                              _("unsupported reloc %u"),
1357                              r_type);
1358       break;
1359
1360     case elfcpp::R_386_TLS_LDM:
1361       if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
1362         {
1363           gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1364                                  _("both SUN and GNU model "
1365                                    "TLS relocations"));
1366           break;
1367         }
1368       this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
1369       if (optimized_type == tls::TLSOPT_TO_LE)
1370         {
1371           this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
1372                              value, view, view_size);
1373           break;
1374         }
1375       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1376                              _("unsupported reloc %u"),
1377                              r_type);
1378       break;
1379
1380     case elfcpp::R_386_TLS_LDO_32:
1381       // This reloc can appear in debugging sections, in which case we
1382       // won't see the TLS_LDM reloc.  The local_dynamic_type field
1383       // tells us this.
1384       if (optimized_type != tls::TLSOPT_TO_LE
1385           || this->local_dynamic_type_ == LOCAL_DYNAMIC_NONE)
1386         value = value - tls_segment->vaddr();
1387       else if (this->local_dynamic_type_ == LOCAL_DYNAMIC_GNU)
1388         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1389       else
1390         value = tls_segment->vaddr() + tls_segment->memsz() - value;
1391       Relocate_functions<32, false>::rel32(view, value);
1392       break;
1393
1394     case elfcpp::R_386_TLS_GOTDESC:
1395     case elfcpp::R_386_TLS_DESC_CALL:
1396       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1397                              _("unsupported reloc %u"),
1398                              r_type);
1399       break;
1400     }
1401 }
1402
1403 // Do a relocation in which we convert a TLS Initial-Exec to a
1404 // Local-Exec.
1405
1406 inline void
1407 Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
1408                                     size_t relnum,
1409                                     Output_segment* tls_segment,
1410                                     const elfcpp::Rel<32, false>& rel,
1411                                     unsigned int r_type,
1412                                     elfcpp::Elf_types<32>::Elf_Addr value,
1413                                     unsigned char* view,
1414                                     off_t view_size)
1415 {
1416   // We have to actually change the instructions, which means that we
1417   // need to examine the opcodes to figure out which instruction we
1418   // are looking at.
1419   if (r_type == elfcpp::R_386_TLS_IE)
1420     {
1421       // movl %gs:XX,%eax  ==>  movl $YY,%eax
1422       // movl %gs:XX,%reg  ==>  movl $YY,%reg
1423       // addl %gs:XX,%reg  ==>  addl $YY,%reg
1424       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
1425       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
1426
1427       unsigned char op1 = view[-1];
1428       if (op1 == 0xa1)
1429         {
1430           // movl XX,%eax  ==>  movl $YY,%eax
1431           view[-1] = 0xb8;
1432         }
1433       else
1434         {
1435           tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1436
1437           unsigned char op2 = view[-2];
1438           if (op2 == 0x8b)
1439             {
1440               // movl XX,%reg  ==>  movl $YY,%reg
1441               tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1442                              (op1 & 0xc7) == 0x05);
1443               view[-2] = 0xc7;
1444               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1445             }
1446           else if (op2 == 0x03)
1447             {
1448               // addl XX,%reg  ==>  addl $YY,%reg
1449               tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1450                              (op1 & 0xc7) == 0x05);
1451               view[-2] = 0x81;
1452               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1453             }
1454           else
1455             tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
1456         }
1457     }
1458   else
1459     {
1460       // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1461       // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1462       // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1463       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1464       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
1465
1466       unsigned char op1 = view[-1];
1467       unsigned char op2 = view[-2];
1468       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1469                      (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
1470       if (op2 == 0x8b)
1471         {
1472           // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1473           view[-2] = 0xc7;
1474           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1475         }
1476       else if (op2 == 0x2b)
1477         {
1478           // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1479           view[-2] = 0x81;
1480           view[-1] = 0xe8 | ((op1 >> 3) & 7);
1481         }
1482       else if (op2 == 0x03)
1483         {
1484           // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1485           view[-2] = 0x81;
1486           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1487         }
1488       else
1489         tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
1490     }
1491
1492   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1493   if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
1494     value = - value;
1495
1496   Relocate_functions<32, false>::rel32(view, value);
1497 }
1498
1499 // Do a relocation in which we convert a TLS General-Dynamic to a
1500 // Local-Exec.
1501
1502 inline void
1503 Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
1504                                     size_t relnum,
1505                                     Output_segment* tls_segment,
1506                                     const elfcpp::Rel<32, false>& rel,
1507                                     unsigned int,
1508                                     elfcpp::Elf_types<32>::Elf_Addr value,
1509                                     unsigned char* view,
1510                                     off_t view_size)
1511 {
1512   // leal foo(,%reg,1),%eax; call ___tls_get_addr
1513   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1514   // leal foo(%reg),%eax; call ___tls_get_addr
1515   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1516
1517   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1518   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1519
1520   unsigned char op1 = view[-1];
1521   unsigned char op2 = view[-2];
1522
1523   tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1524                  op2 == 0x8d || op2 == 0x04);
1525   tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1526
1527   int roff = 5;
1528
1529   if (op2 == 0x04)
1530     {
1531       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
1532       tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
1533       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1534                      ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
1535       memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1536     }
1537   else
1538     {
1539       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1540                      (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1541       if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
1542           && view[9] == 0x90)
1543         {
1544           // There is a trailing nop.  Use the size byte subl.
1545           memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1546           roff = 6;
1547         }
1548       else
1549         {
1550           // Use the five byte subl.
1551           memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1552         }
1553     }
1554
1555   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1556   Relocate_functions<32, false>::rel32(view + roff, value);
1557
1558   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1559   // We can skip it.
1560   this->skip_call_tls_get_addr_ = true;
1561 }
1562
1563 // Do a relocation in which we convert a TLS Local-Dynamic to a
1564 // Local-Exec.
1565
1566 inline void
1567 Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
1568                                     size_t relnum,
1569                                     Output_segment*,
1570                                     const elfcpp::Rel<32, false>& rel,
1571                                     unsigned int,
1572                                     elfcpp::Elf_types<32>::Elf_Addr,
1573                                     unsigned char* view,
1574                                     off_t view_size)
1575 {
1576   // leal foo(%reg), %eax; call ___tls_get_addr
1577   // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
1578
1579   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1580   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1581
1582   // FIXME: Does this test really always pass?
1583   tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1584                  view[-2] == 0x8d && view[-1] == 0x83);
1585
1586   tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1587
1588   memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
1589
1590   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1591   // We can skip it.
1592   this->skip_call_tls_get_addr_ = true;
1593 }
1594
1595 // Relocate section data.
1596
1597 void
1598 Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
1599                               unsigned int sh_type,
1600                               const unsigned char* prelocs,
1601                               size_t reloc_count,
1602                               unsigned char* view,
1603                               elfcpp::Elf_types<32>::Elf_Addr address,
1604                               off_t view_size)
1605 {
1606   gold_assert(sh_type == elfcpp::SHT_REL);
1607
1608   gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
1609                          Target_i386::Relocate>(
1610     relinfo,
1611     this,
1612     prelocs,
1613     reloc_count,
1614     view,
1615     address,
1616     view_size);
1617 }
1618
1619 // Return the value to use for a dynamic which requires special
1620 // treatment.  This is how we support equality comparisons of function
1621 // pointers across shared library boundaries, as described in the
1622 // processor specific ABI supplement.
1623
1624 uint64_t
1625 Target_i386::do_dynsym_value(const Symbol* gsym) const
1626 {
1627   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1628   return this->plt_section()->address() + gsym->plt_offset();
1629 }
1630
1631 // Return a string used to fill a code section with nops to take up
1632 // the specified length.
1633
1634 std::string
1635 Target_i386::do_code_fill(off_t length)
1636 {
1637   if (length >= 16)
1638     {
1639       // Build a jmp instruction to skip over the bytes.
1640       unsigned char jmp[5];
1641       jmp[0] = 0xe9;
1642       elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
1643       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1644               + std::string(length - 5, '\0'));
1645     }
1646
1647   // Nop sequences of various lengths.
1648   const char nop1[1] = { 0x90 };                   // nop
1649   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1650   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1651   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1652   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1653                          0x00 };                   // leal 0(%esi,1),%esi
1654   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1655                          0x00, 0x00 };
1656   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1657                          0x00, 0x00, 0x00 };
1658   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1659                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1660   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1661                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1662                          0x00 };
1663   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1664                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1665                            0x00, 0x00 };
1666   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1667                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1668                            0x00, 0x00, 0x00 };
1669   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1670                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1671                            0x00, 0x00, 0x00, 0x00 };
1672   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1673                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1674                            0x27, 0x00, 0x00, 0x00,
1675                            0x00 };
1676   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1677                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1678                            0xbc, 0x27, 0x00, 0x00,
1679                            0x00, 0x00 };
1680   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1681                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1682                            0x90, 0x90, 0x90, 0x90,
1683                            0x90, 0x90, 0x90 };
1684
1685   const char* nops[16] = {
1686     NULL,
1687     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1688     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1689   };
1690
1691   return std::string(nops[length], length);
1692 }
1693
1694 // The selector for i386 object files.
1695
1696 class Target_selector_i386 : public Target_selector
1697 {
1698 public:
1699   Target_selector_i386()
1700     : Target_selector(elfcpp::EM_386, 32, false)
1701   { }
1702
1703   Target*
1704   recognize(int machine, int osabi, int abiversion);
1705
1706  private:
1707   Target_i386* target_;
1708 };
1709
1710 // Recognize an i386 object file when we already know that the machine
1711 // number is EM_386.
1712
1713 Target*
1714 Target_selector_i386::recognize(int, int, int)
1715 {
1716   if (this->target_ == NULL)
1717     this->target_ = new Target_i386();
1718   return this->target_;
1719 }
1720
1721 Target_selector_i386 target_selector_i386;
1722
1723 } // End anonymous namespace.