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