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
  39 namespace
  40 {
  41
  42 using namespace gold;
  43
  44 class Output_data_plt_i386;
  45
  46 // The i386 target class.
  47
  48 class Target_i386 : public Sized_target<32, false>
  49 {
  50  public:
  51   typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
  52
  53   Target_i386()
  54     : Sized_target<32, false>(&i386_info),
  55       got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
  56       copy_relocs_(NULL), dynbss_(NULL)
  57   { }
  58
  59   // Scan the relocations to look for symbol adjustments.
  60   void
  61   scan_relocs(const General_options& options,
  62               Symbol_table* symtab,
  63               Layout* layout,
  64               Sized_relobj<32, false>* object,
  65               unsigned int data_shndx,
  66               unsigned int sh_type,
  67               const unsigned char* prelocs,
  68               size_t reloc_count,
  69               size_t local_symbol_count,
  70               const unsigned char* plocal_symbols,
  71               Symbol** global_symbols);
  72
  73   // Finalize the sections.
  74   void
  75   do_finalize_sections(Layout*);
  76
  77   // Return the value to use for a dynamic which requires special
  78   // treatment.
  79   uint64_t
  80   do_dynsym_value(const Symbol*) const;
  81
  82   // Relocate a section.
  83   void
  84   relocate_section(const Relocate_info<32, false>*,
  85                    unsigned int sh_type,
  86                    const unsigned char* prelocs,
  87                    size_t reloc_count,
  88                    unsigned char* view,
  89                    elfcpp::Elf_types<32>::Elf_Addr view_address,
  90                    off_t view_size);
  91
  92   // Return a string used to fill a code section with nops.
  93   std::string
  94   do_code_fill(off_t length);
  95
  96  private:
  97   // The class which scans relocations.
  98   struct Scan
  99   {
 100     inline void
 101     local(const General_options& options, Symbol_table* symtab,
 102           Layout* layout, Target_i386* target,
 103           Sized_relobj<32, false>* object,
 104           unsigned int data_shndx,
 105           const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
 106           const elfcpp::Sym<32, false>& lsym);
 107
 108     inline void
 109     global(const General_options& options, Symbol_table* symtab,
 110            Layout* layout, Target_i386* target,
 111            Sized_relobj<32, false>* object,
 112            unsigned int data_shndx,
 113            const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
 114            Symbol* gsym);
 115   };
 116
 117   // The class which implements relocation.
 118   class Relocate
 119   {
 120    public:
 121     Relocate()
 122       : skip_call_tls_get_addr_(false),
 123         local_dynamic_type_(LOCAL_DYNAMIC_NONE)
 124     { }
 125
 126     ~Relocate()
 127     {
 128       if (this->skip_call_tls_get_addr_)
 129         {
 130           // FIXME: This needs to specify the location somehow.
 131           fprintf(stderr, _("%s: missing expected TLS relocation\n"),
 132                   program_name);
 133           gold_exit(false);
 134         }
 135     }
 136
 137     // Do a relocation.  Return false if the caller should not issue
 138     // any warnings about this relocation.
 139     inline bool
 140     relocate(const Relocate_info<32, false>*, Target_i386*, size_t relnum,
 141              const elfcpp::Rel<32, false>&,
 142              unsigned int r_type, const Sized_symbol<32>*,
 143              const Symbol_value<32>*,
 144              unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
 145              off_t);
 146
 147    private:
 148     // Do a TLS relocation.
 149     inline void
 150     relocate_tls(const Relocate_info<32, false>*, size_t relnum,
 151                  const elfcpp::Rel<32, false>&,
 152                  unsigned int r_type, const Sized_symbol<32>*,
 153                  const Symbol_value<32>*,
 154                  unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, off_t);
 155
 156     // Do a TLS Initial-Exec to Local-Exec transition.
 157     static inline void
 158     tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum,
 159                  Output_segment* tls_segment,
 160                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 161                  elfcpp::Elf_types<32>::Elf_Addr value,
 162                  unsigned char* view,
 163                  off_t view_size);
 164
 165     // Do a TLS Global-Dynamic to Local-Exec transition.
 166     inline void
 167     tls_gd_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 Local-Dynamic to Local-Exec transition.
 175     inline void
 176     tls_ld_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     // Check the range for a TLS relocation.
 184     static inline void
 185     check_range(const Relocate_info<32, false>*, size_t relnum,
 186                 const elfcpp::Rel<32, false>&, off_t, off_t);
 187
 188     // Check the validity of a TLS relocation.  This is like assert.
 189     static inline void
 190     check_tls(const Relocate_info<32, false>*, size_t relnum,
 191               const elfcpp::Rel<32, false>&, bool);
 192
 193     // We need to keep track of which type of local dynamic relocation
 194     // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
 195     enum Local_dynamic_type
 196     {
 197       LOCAL_DYNAMIC_NONE,
 198       LOCAL_DYNAMIC_SUN,
 199       LOCAL_DYNAMIC_GNU
 200     };
 201
 202     // This is set if we should skip the next reloc, which should be a
 203     // PLT32 reloc against ___tls_get_addr.
 204     bool skip_call_tls_get_addr_;
 205     // The type of local dynamic relocation we have seen in the section
 206     // being relocated, if any.
 207     Local_dynamic_type local_dynamic_type_;
 208   };
 209
 210   // Adjust TLS relocation type based on the options and whether this
 211   // is a local symbol.
 212   static unsigned int
 213   optimize_tls_reloc(bool is_final, int r_type);
 214
 215   // Get the GOT section, creating it if necessary.
 216   Output_data_got<32, false>*
 217   got_section(Symbol_table*, Layout*);
 218
 219   // Create a PLT entry for a global symbol.
 220   void
 221   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 222
 223   // Get the PLT section.
 224   const Output_data_plt_i386*
 225   plt_section() const
 226   {
 227     gold_assert(this->plt_ != NULL);
 228     return this->plt_;
 229   }
 230
 231   // Get the dynamic reloc section, creating it if necessary.
 232   Reloc_section*
 233   rel_dyn_section(Layout*);
 234
 235   // Copy a relocation against a global symbol.
 236   void
 237   copy_reloc(const General_options*, Symbol_table*, Layout*,
 238              Sized_relobj<32, false>*, unsigned int,
 239              Symbol*, const elfcpp::Rel<32, false>&);
 240
 241   // Information about this specific target which we pass to the
 242   // general Target structure.
 243   static const Target::Target_info i386_info;
 244
 245   // The GOT section.
 246   Output_data_got<32, false>* got_;
 247   // The PLT section.
 248   Output_data_plt_i386* plt_;
 249   // The GOT PLT section.
 250   Output_data_space* got_plt_;
 251   // The dynamic reloc section.
 252   Reloc_section* rel_dyn_;
 253   // Relocs saved to avoid a COPY reloc.
 254   Copy_relocs<32, false>* copy_relocs_;
 255   // Space for variables copied with a COPY reloc.
 256   Output_data_space* dynbss_;
 257 };
 258
 259 const Target::Target_info Target_i386::i386_info =
 260 {
 261   32,                   // size
 262   false,                // is_big_endian
 263   elfcpp::EM_386,       // machine_code
 264   false,                // has_make_symbol
 265   false,                // has_resolve
 266   true,                 // has_code_fill
 267   "/usr/lib/libc.so.1", // dynamic_linker
 268   0x08048000,           // 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       // Define the symbol in the .dynbss section.
 654       symtab->define_in_output_data(this, ssym->name(), ssym->version(),
 655                                     dynbss, offset, symsize, ssym->type(),
 656                                     ssym->binding(), ssym->visibility(),
 657                                     ssym->nonvis(), false, false);
 658
 659       // Add the COPY reloc.
 660       ssym->set_needs_dynsym_entry();
 661       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
 662       rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset);
 663     }
 664 }
 665
 666 // Optimize the TLS relocation type based on what we know about the
 667 // symbol.  IS_FINAL is true if the final address of this symbol is
 668 // known at link time.
 669
 670 unsigned int
 671 Target_i386::optimize_tls_reloc(bool is_final, int r_type)
 672 {
 673   // If we are generating a shared library, then we can't do anything
 674   // in the linker.
 675   if (parameters->output_is_shared())
 676     return r_type;
 677
 678   switch (r_type)
 679     {
 680     case elfcpp::R_386_TLS_GD:
 681     case elfcpp::R_386_TLS_GOTDESC:
 682     case elfcpp::R_386_TLS_DESC_CALL:
 683       // These are Global-Dynamic which permits fully general TLS
 684       // access.  Since we know that we are generating an executable,
 685       // we can convert this to Initial-Exec.  If we also know that
 686       // this is a local symbol, we can further switch to Local-Exec.
 687       if (is_final)
 688         return elfcpp::R_386_TLS_LE_32;
 689       return elfcpp::R_386_TLS_IE_32;
 690
 691     case elfcpp::R_386_TLS_LDM:
 692       // This is Local-Dynamic, which refers to a local symbol in the
 693       // dynamic TLS block.  Since we know that we generating an
 694       // executable, we can switch to Local-Exec.
 695       return elfcpp::R_386_TLS_LE_32;
 696
 697     case elfcpp::R_386_TLS_LDO_32:
 698       // Another type of Local-Dynamic relocation.  We return a
 699       // different value as we need to negate the thread segment
 700       // offset.  FIXME: Returning reloc types makes no sense.
 701       return elfcpp::R_386_TLS_LE;
 702
 703     case elfcpp::R_386_TLS_IE:
 704     case elfcpp::R_386_TLS_GOTIE:
 705     case elfcpp::R_386_TLS_IE_32:
 706       // These are Initial-Exec relocs which get the thread offset
 707       // from the GOT.  If we know that we are linking against the
 708       // local symbol, we can switch to Local-Exec, which links the
 709       // thread offset into the instruction.
 710       if (is_final)
 711         return elfcpp::R_386_TLS_LE_32;
 712       return r_type;
 713
 714     case elfcpp::R_386_TLS_LE:
 715     case elfcpp::R_386_TLS_LE_32:
 716       // When we already have Local-Exec, there is nothing further we
 717       // can do.
 718       return r_type;
 719
 720     default:
 721       gold_unreachable();
 722     }
 723 }
 724
 725 // Scan a relocation for a local symbol.
 726
 727 inline void
 728 Target_i386::Scan::local(const General_options&,
 729                          Symbol_table* symtab,
 730                          Layout* layout,
 731                          Target_i386* target,
 732                          Sized_relobj<32, false>* object,
 733                          unsigned int,
 734                          const elfcpp::Rel<32, false>&,
 735                          unsigned int r_type,
 736                          const elfcpp::Sym<32, false>&)
 737 {
 738   switch (r_type)
 739     {
 740     case elfcpp::R_386_NONE:
 741     case elfcpp::R_386_GNU_VTINHERIT:
 742     case elfcpp::R_386_GNU_VTENTRY:
 743       break;
 744
 745     case elfcpp::R_386_32:
 746     case elfcpp::R_386_16:
 747     case elfcpp::R_386_8:
 748       // FIXME: If we are generating a shared object we need to copy
 749       // this relocation into the object.
 750       gold_assert(!parameters->output_is_shared());
 751       break;
 752
 753     case elfcpp::R_386_PC32:
 754     case elfcpp::R_386_PC16:
 755     case elfcpp::R_386_PC8:
 756       break;
 757
 758     case elfcpp::R_386_GOTOFF:
 759     case elfcpp::R_386_GOTPC:
 760       // We need a GOT section.
 761       target->got_section(symtab, layout);
 762       break;
 763
 764     case elfcpp::R_386_COPY:
 765     case elfcpp::R_386_GLOB_DAT:
 766     case elfcpp::R_386_JUMP_SLOT:
 767     case elfcpp::R_386_RELATIVE:
 768       // These are outstanding tls relocs, which are unexpected when
 769       // linking.
 770     case elfcpp::R_386_TLS_TPOFF:
 771     case elfcpp::R_386_TLS_DTPMOD32:
 772     case elfcpp::R_386_TLS_DTPOFF32:
 773     case elfcpp::R_386_TLS_TPOFF32:
 774     case elfcpp::R_386_TLS_DESC:
 775       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
 776               program_name, object->name().c_str(), r_type);
 777       gold_exit(false);
 778       break;
 779
 780       // These are initial tls relocs, which are expected when
 781       // linking.
 782     case elfcpp::R_386_TLS_IE:
 783     case elfcpp::R_386_TLS_GOTIE:
 784     case elfcpp::R_386_TLS_LE:
 785     case elfcpp::R_386_TLS_GD:
 786     case elfcpp::R_386_TLS_LDM:
 787     case elfcpp::R_386_TLS_LDO_32:
 788     case elfcpp::R_386_TLS_IE_32:
 789     case elfcpp::R_386_TLS_LE_32:
 790     case elfcpp::R_386_TLS_GOTDESC:
 791     case elfcpp::R_386_TLS_DESC_CALL:
 792       {
 793         bool output_is_shared = parameters->output_is_shared();
 794         r_type = Target_i386::optimize_tls_reloc(!output_is_shared,
 795                                                  r_type);
 796         switch (r_type)
 797           {
 798           case elfcpp::R_386_TLS_LE:
 799           case elfcpp::R_386_TLS_LE_32:
 800             // FIXME: If generating a shared object, we need to copy
 801             // this relocation into the object.
 802             gold_assert(!output_is_shared);
 803             break;
 804
 805           case elfcpp::R_386_TLS_LDM:
 806           case elfcpp::R_386_TLS_LDO_32:
 807             break;
 808
 809           case elfcpp::R_386_TLS_IE:
 810           case elfcpp::R_386_TLS_GOTIE:
 811           case elfcpp::R_386_TLS_GD:
 812           case elfcpp::R_386_TLS_IE_32:
 813           case elfcpp::R_386_TLS_GOTDESC:
 814           case elfcpp::R_386_TLS_DESC_CALL:
 815             fprintf(stderr,
 816                     _("%s: %s: unsupported reloc %u against local symbol\n"),
 817                     program_name, object->name().c_str(), r_type);
 818             break;
 819           }
 820       }
 821       break;
 822
 823     case elfcpp::R_386_GOT32:
 824     case elfcpp::R_386_PLT32:
 825     case elfcpp::R_386_32PLT:
 826     case elfcpp::R_386_TLS_GD_32:
 827     case elfcpp::R_386_TLS_GD_PUSH:
 828     case elfcpp::R_386_TLS_GD_CALL:
 829     case elfcpp::R_386_TLS_GD_POP:
 830     case elfcpp::R_386_TLS_LDM_32:
 831     case elfcpp::R_386_TLS_LDM_PUSH:
 832     case elfcpp::R_386_TLS_LDM_CALL:
 833     case elfcpp::R_386_TLS_LDM_POP:
 834     case elfcpp::R_386_USED_BY_INTEL_200:
 835     default:
 836       fprintf(stderr, _("%s: %s: unsupported reloc %u against local symbol\n"),
 837               program_name, object->name().c_str(), r_type);
 838       break;
 839     }
 840 }
 841
 842 // Scan a relocation for a global symbol.
 843
 844 inline void
 845 Target_i386::Scan::global(const General_options& options,
 846                           Symbol_table* symtab,
 847                           Layout* layout,
 848                           Target_i386* target,
 849                           Sized_relobj<32, false>* object,
 850                           unsigned int data_shndx,
 851                           const elfcpp::Rel<32, false>& reloc,
 852                           unsigned int r_type,
 853                           Symbol* gsym)
 854 {
 855   switch (r_type)
 856     {
 857     case elfcpp::R_386_NONE:
 858     case elfcpp::R_386_GNU_VTINHERIT:
 859     case elfcpp::R_386_GNU_VTENTRY:
 860       break;
 861
 862     case elfcpp::R_386_32:
 863     case elfcpp::R_386_PC32:
 864     case elfcpp::R_386_16:
 865     case elfcpp::R_386_PC16:
 866     case elfcpp::R_386_8:
 867     case elfcpp::R_386_PC8:
 868       // FIXME: If we are generating a shared object we may need to
 869       // copy this relocation into the object.  If this symbol is
 870       // defined in a shared object, we may need to copy this
 871       // relocation in order to avoid a COPY relocation.
 872       gold_assert(!parameters->output_is_shared());
 873
 874       if (gsym->is_from_dynobj())
 875         {
 876           // This symbol is defined in a dynamic object.  If it is a
 877           // function, we make a PLT entry.  Otherwise we need to
 878           // either generate a COPY reloc or copy this reloc.
 879           if (gsym->type() == elfcpp::STT_FUNC)
 880             {
 881               target->make_plt_entry(symtab, layout, gsym);
 882
 883               // If this is not a PC relative reference, then we may
 884               // be taking the address of the function.  In that case
 885               // we need to set the entry in the dynamic symbol table
 886               // to the address of the PLT entry.
 887               if (r_type != elfcpp::R_386_PC32
 888                   && r_type != elfcpp::R_386_PC16
 889                   && r_type != elfcpp::R_386_PC8)
 890                 gsym->set_needs_dynsym_value();
 891             }
 892           else
 893             target->copy_reloc(&options, symtab, layout, object, data_shndx,
 894                                gsym, reloc);
 895         }
 896
 897       break;
 898
 899     case elfcpp::R_386_GOT32:
 900       {
 901         // The symbol requires a GOT entry.
 902         Output_data_got<32, false>* got = target->got_section(symtab, layout);
 903         if (got->add_global(gsym))
 904           {
 905             // If this symbol is not fully resolved, we need to add a
 906             // dynamic relocation for it.
 907             if (!gsym->final_value_is_known())
 908               {
 909                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 910                 rel_dyn->add_global(gsym, elfcpp::R_386_GLOB_DAT, got,
 911                                     gsym->got_offset());
 912               }
 913           }
 914       }
 915       break;
 916
 917     case elfcpp::R_386_PLT32:
 918       // If the symbol is fully resolved, this is just a PC32 reloc.
 919       // Otherwise we need a PLT entry.
 920       if (gsym->final_value_is_known())
 921         break;
 922       target->make_plt_entry(symtab, layout, gsym);
 923       break;
 924
 925     case elfcpp::R_386_GOTOFF:
 926     case elfcpp::R_386_GOTPC:
 927       // We need a GOT section.
 928       target->got_section(symtab, layout);
 929       break;
 930
 931     case elfcpp::R_386_COPY:
 932     case elfcpp::R_386_GLOB_DAT:
 933     case elfcpp::R_386_JUMP_SLOT:
 934     case elfcpp::R_386_RELATIVE:
 935       // These are outstanding tls relocs, which are unexpected when
 936       // linking.
 937     case elfcpp::R_386_TLS_TPOFF:
 938     case elfcpp::R_386_TLS_DTPMOD32:
 939     case elfcpp::R_386_TLS_DTPOFF32:
 940     case elfcpp::R_386_TLS_TPOFF32:
 941     case elfcpp::R_386_TLS_DESC:
 942       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
 943               program_name, object->name().c_str(), r_type);
 944       gold_exit(false);
 945       break;
 946
 947       // These are initial tls relocs, which are expected when
 948       // linking.
 949     case elfcpp::R_386_TLS_IE:
 950     case elfcpp::R_386_TLS_GOTIE:
 951     case elfcpp::R_386_TLS_LE:
 952     case elfcpp::R_386_TLS_GD:
 953     case elfcpp::R_386_TLS_LDM:
 954     case elfcpp::R_386_TLS_LDO_32:
 955     case elfcpp::R_386_TLS_IE_32:
 956     case elfcpp::R_386_TLS_LE_32:
 957     case elfcpp::R_386_TLS_GOTDESC:
 958     case elfcpp::R_386_TLS_DESC_CALL:
 959       {
 960         const bool is_final = gsym->final_value_is_known();
 961         r_type = Target_i386::optimize_tls_reloc(is_final, r_type);
 962         switch (r_type)
 963           {
 964           case elfcpp::R_386_TLS_LE:
 965           case elfcpp::R_386_TLS_LE_32:
 966             // FIXME: If generating a shared object, we need to copy
 967             // this relocation into the object.
 968             gold_assert(!parameters->output_is_shared());
 969             break;
 970
 971           case elfcpp::R_386_TLS_LDM:
 972           case elfcpp::R_386_TLS_LDO_32:
 973             break;
 974
 975           case elfcpp::R_386_TLS_IE:
 976           case elfcpp::R_386_TLS_GOTIE:
 977           case elfcpp::R_386_TLS_GD:
 978           case elfcpp::R_386_TLS_IE_32:
 979           case elfcpp::R_386_TLS_GOTDESC:
 980           case elfcpp::R_386_TLS_DESC_CALL:
 981             fprintf(stderr,
 982                     _("%s: %s: unsupported reloc %u "
 983                       "against global symbol %s\n"),
 984                     program_name, object->name().c_str(), r_type,
 985                     gsym->name());
 986             break;
 987           }
 988       }
 989       break;
 990
 991     case elfcpp::R_386_32PLT:
 992     case elfcpp::R_386_TLS_GD_32:
 993     case elfcpp::R_386_TLS_GD_PUSH:
 994     case elfcpp::R_386_TLS_GD_CALL:
 995     case elfcpp::R_386_TLS_GD_POP:
 996     case elfcpp::R_386_TLS_LDM_32:
 997     case elfcpp::R_386_TLS_LDM_PUSH:
 998     case elfcpp::R_386_TLS_LDM_CALL:
 999     case elfcpp::R_386_TLS_LDM_POP:
1000     case elfcpp::R_386_USED_BY_INTEL_200:
1001     default:
1002       fprintf(stderr,
1003               _("%s: %s: unsupported reloc %u against global symbol %s\n"),
1004               program_name, object->name().c_str(), r_type, gsym->name());
1005       break;
1006     }
1007 }
1008
1009 // Scan relocations for a section.
1010
1011 void
1012 Target_i386::scan_relocs(const General_options& options,
1013                          Symbol_table* symtab,
1014                          Layout* layout,
1015                          Sized_relobj<32, false>* object,
1016                          unsigned int data_shndx,
1017                          unsigned int sh_type,
1018                          const unsigned char* prelocs,
1019                          size_t reloc_count,
1020                          size_t local_symbol_count,
1021                          const unsigned char* plocal_symbols,
1022                          Symbol** global_symbols)
1023 {
1024   if (sh_type == elfcpp::SHT_RELA)
1025     {
1026       fprintf(stderr, _("%s: %s: unsupported RELA reloc section\n"),
1027               program_name, object->name().c_str());
1028       gold_exit(false);
1029     }
1030
1031   gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
1032                     Target_i386::Scan>(
1033     options,
1034     symtab,
1035     layout,
1036     this,
1037     object,
1038     data_shndx,
1039     prelocs,
1040     reloc_count,
1041     local_symbol_count,
1042     plocal_symbols,
1043     global_symbols);
1044 }
1045
1046 // Finalize the sections.
1047
1048 void
1049 Target_i386::do_finalize_sections(Layout* layout)
1050 {
1051   // Fill in some more dynamic tags.
1052   Output_data_dynamic* const odyn = layout->dynamic_data();
1053   if (odyn != NULL)
1054     {
1055       if (this->got_plt_ != NULL)
1056         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1057
1058       if (this->plt_ != NULL)
1059         {
1060           const Output_data* od = this->plt_->rel_plt();
1061           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1062           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1063           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL);
1064         }
1065
1066       if (this->rel_dyn_ != NULL)
1067         {
1068           const Output_data* od = this->rel_dyn_;
1069           odyn->add_section_address(elfcpp::DT_REL, od);
1070           odyn->add_section_size(elfcpp::DT_RELSZ, od);
1071           odyn->add_constant(elfcpp::DT_RELENT,
1072                              elfcpp::Elf_sizes<32>::rel_size);
1073         }
1074
1075       if (!parameters->output_is_shared())
1076         {
1077           // The value of the DT_DEBUG tag is filled in by the dynamic
1078           // linker at run time, and used by the debugger.
1079           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1080         }
1081     }
1082
1083   // Emit any relocs we saved in an attempt to avoid generating COPY
1084   // relocs.
1085   if (this->copy_relocs_ == NULL)
1086     return;
1087   if (this->copy_relocs_->any_to_emit())
1088     {
1089       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1090       this->copy_relocs_->emit(rel_dyn);
1091     }
1092   delete this->copy_relocs_;
1093   this->copy_relocs_ = NULL;
1094 }
1095
1096 // Perform a relocation.
1097
1098 inline bool
1099 Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
1100                                 Target_i386* target,
1101                                 size_t relnum,
1102                                 const elfcpp::Rel<32, false>& rel,
1103                                 unsigned int r_type,
1104                                 const Sized_symbol<32>* gsym,
1105                                 const Symbol_value<32>* psymval,
1106                                 unsigned char* view,
1107                                 elfcpp::Elf_types<32>::Elf_Addr address,
1108                                 off_t view_size)
1109 {
1110   if (this->skip_call_tls_get_addr_)
1111     {
1112       if (r_type != elfcpp::R_386_PLT32
1113           || gsym == NULL
1114           || strcmp(gsym->name(), "___tls_get_addr") != 0)
1115         {
1116           fprintf(stderr, _("%s: %s: missing expected TLS relocation\n"),
1117                   program_name,
1118                   relinfo->location(relnum, rel.get_r_offset()).c_str());
1119           gold_exit(false);
1120         }
1121
1122       this->skip_call_tls_get_addr_ = false;
1123
1124       return false;
1125     }
1126
1127   // Pick the value to use for symbols defined in shared objects.
1128   Symbol_value<32> symval;
1129   if (gsym != NULL && gsym->is_from_dynobj() && gsym->has_plt_offset())
1130     {
1131       symval.set_output_value(target->plt_section()->address()
1132                               + gsym->plt_offset());
1133       psymval = &symval;
1134     }
1135
1136   const Sized_relobj<32, false>* object = relinfo->object;
1137
1138   switch (r_type)
1139     {
1140     case elfcpp::R_386_NONE:
1141     case elfcpp::R_386_GNU_VTINHERIT:
1142     case elfcpp::R_386_GNU_VTENTRY:
1143       break;
1144
1145     case elfcpp::R_386_32:
1146       Relocate_functions<32, false>::rel32(view, object, psymval);
1147       break;
1148
1149     case elfcpp::R_386_PC32:
1150       Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1151       break;
1152
1153     case elfcpp::R_386_16:
1154       Relocate_functions<32, false>::rel16(view, object, psymval);
1155       break;
1156
1157     case elfcpp::R_386_PC16:
1158       Relocate_functions<32, false>::pcrel16(view, object, psymval, address);
1159       break;
1160
1161     case elfcpp::R_386_8:
1162       Relocate_functions<32, false>::rel8(view, object, psymval);
1163       break;
1164
1165     case elfcpp::R_386_PC8:
1166       Relocate_functions<32, false>::pcrel8(view, object, psymval, address);
1167       break;
1168
1169     case elfcpp::R_386_PLT32:
1170       gold_assert(gsym->has_plt_offset()
1171                   || gsym->final_value_is_known());
1172       Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1173       break;
1174
1175     case elfcpp::R_386_GOT32:
1176       // Local GOT offsets not yet supported.
1177       gold_assert(gsym);
1178       gold_assert(gsym->has_got_offset());
1179       Relocate_functions<32, false>::rel32(view, gsym->got_offset());
1180       break;
1181
1182     case elfcpp::R_386_GOTOFF:
1183       {
1184         elfcpp::Elf_types<32>::Elf_Addr value;
1185         value = (psymval->value(object, 0)
1186                  - target->got_section(NULL, NULL)->address());
1187         Relocate_functions<32, false>::rel32(view, value);
1188       }
1189       break;
1190
1191     case elfcpp::R_386_GOTPC:
1192       {
1193         elfcpp::Elf_types<32>::Elf_Addr value;
1194         value = target->got_section(NULL, NULL)->address();
1195         Relocate_functions<32, false>::pcrel32(view, value, address);
1196       }
1197       break;
1198
1199     case elfcpp::R_386_COPY:
1200     case elfcpp::R_386_GLOB_DAT:
1201     case elfcpp::R_386_JUMP_SLOT:
1202     case elfcpp::R_386_RELATIVE:
1203       // These are outstanding tls relocs, which are unexpected when
1204       // linking.
1205     case elfcpp::R_386_TLS_TPOFF:
1206     case elfcpp::R_386_TLS_DTPMOD32:
1207     case elfcpp::R_386_TLS_DTPOFF32:
1208     case elfcpp::R_386_TLS_TPOFF32:
1209     case elfcpp::R_386_TLS_DESC:
1210       fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"),
1211               program_name,
1212               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1213               r_type);
1214       gold_exit(false);
1215       break;
1216
1217       // These are initial tls relocs, which are expected when
1218       // linking.
1219     case elfcpp::R_386_TLS_IE:
1220     case elfcpp::R_386_TLS_GOTIE:
1221     case elfcpp::R_386_TLS_LE:
1222     case elfcpp::R_386_TLS_GD:
1223     case elfcpp::R_386_TLS_LDM:
1224     case elfcpp::R_386_TLS_LDO_32:
1225     case elfcpp::R_386_TLS_IE_32:
1226     case elfcpp::R_386_TLS_LE_32:
1227     case elfcpp::R_386_TLS_GOTDESC:
1228     case elfcpp::R_386_TLS_DESC_CALL:
1229       this->relocate_tls(relinfo, relnum, rel, r_type, gsym, psymval, view,
1230                          address, view_size);
1231       break;
1232
1233     case elfcpp::R_386_32PLT:
1234     case elfcpp::R_386_TLS_GD_32:
1235     case elfcpp::R_386_TLS_GD_PUSH:
1236     case elfcpp::R_386_TLS_GD_CALL:
1237     case elfcpp::R_386_TLS_GD_POP:
1238     case elfcpp::R_386_TLS_LDM_32:
1239     case elfcpp::R_386_TLS_LDM_PUSH:
1240     case elfcpp::R_386_TLS_LDM_CALL:
1241     case elfcpp::R_386_TLS_LDM_POP:
1242     case elfcpp::R_386_USED_BY_INTEL_200:
1243     default:
1244       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1245               program_name,
1246               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1247               r_type);
1248       // gold_exit(false);
1249       break;
1250     }
1251
1252   return true;
1253 }
1254
1255 // Perform a TLS relocation.
1256
1257 inline void
1258 Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
1259                                     size_t relnum,
1260                                     const elfcpp::Rel<32, false>& rel,
1261                                     unsigned int r_type,
1262                                     const Sized_symbol<32>* gsym,
1263                                     const Symbol_value<32>* psymval,
1264                                     unsigned char* view,
1265                                     elfcpp::Elf_types<32>::Elf_Addr,
1266                                     off_t view_size)
1267 {
1268   Output_segment* tls_segment = relinfo->layout->tls_segment();
1269   if (tls_segment == NULL)
1270     {
1271       fprintf(stderr, _("%s: %s: TLS reloc but no TLS segment\n"),
1272               program_name,
1273               relinfo->location(relnum, rel.get_r_offset()).c_str());
1274       gold_exit(false);
1275     }
1276
1277   elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(relinfo->object, 0);
1278
1279   const bool is_final = (gsym == NULL
1280                          ? !parameters->output_is_shared()
1281                          : gsym->final_value_is_known());
1282   const unsigned int opt_r_type =
1283     Target_i386::optimize_tls_reloc(is_final, r_type);
1284   switch (r_type)
1285     {
1286     case elfcpp::R_386_TLS_LE_32:
1287       value = tls_segment->vaddr() + tls_segment->memsz() - value;
1288       Relocate_functions<32, false>::rel32(view, value);
1289       break;
1290
1291     case elfcpp::R_386_TLS_LE:
1292       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1293       Relocate_functions<32, false>::rel32(view, value);
1294       break;
1295
1296     case elfcpp::R_386_TLS_IE:
1297     case elfcpp::R_386_TLS_GOTIE:
1298     case elfcpp::R_386_TLS_IE_32:
1299       if (opt_r_type == elfcpp::R_386_TLS_LE_32)
1300         {
1301           Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1302                                               rel, r_type, value, view,
1303                                               view_size);
1304           break;
1305         }
1306       fprintf(stderr, _("%s: %s: unsupported reloc type %u\n"),
1307               program_name,
1308               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1309               r_type);
1310       // gold_exit(false);
1311       break;
1312
1313     case elfcpp::R_386_TLS_GD:
1314       if (opt_r_type == elfcpp::R_386_TLS_LE_32)
1315         {
1316           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1317                              rel, r_type, value, view,
1318                              view_size);
1319           break;
1320         }
1321       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1322               program_name,
1323               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1324               r_type);
1325       // gold_exit(false);
1326       break;
1327
1328     case elfcpp::R_386_TLS_LDM:
1329       if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
1330         {
1331           fprintf(stderr,
1332                   _("%s: %s: both SUN and GNU model TLS relocations\n"),
1333                   program_name,
1334                   relinfo->location(relnum, rel.get_r_offset()).c_str());
1335           gold_exit(false);
1336         }
1337       this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
1338       if (opt_r_type == elfcpp::R_386_TLS_LE_32)
1339         {
1340           this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
1341                              value, view, view_size);
1342           break;
1343         }
1344       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1345               program_name,
1346               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1347               r_type);
1348       // gold_exit(false);
1349       break;
1350
1351     case elfcpp::R_386_TLS_LDO_32:
1352       // This reloc can appear in debugging sections, in which case we
1353       // won't see the TLS_LDM reloc.  The local_dynamic_type field
1354       // tells us this.
1355       if (opt_r_type == elfcpp::R_386_TLS_LDO_32
1356           || this->local_dynamic_type_ == LOCAL_DYNAMIC_NONE)
1357         value = value - tls_segment->vaddr();
1358       else if (this->local_dynamic_type_ == LOCAL_DYNAMIC_GNU)
1359         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1360       else
1361         value = tls_segment->vaddr() + tls_segment->memsz() - value;
1362       Relocate_functions<32, false>::rel32(view, value);
1363       break;
1364
1365     case elfcpp::R_386_TLS_GOTDESC:
1366     case elfcpp::R_386_TLS_DESC_CALL:
1367       fprintf(stderr, _("%s: %s: unsupported reloc %u\n"),
1368               program_name,
1369               relinfo->location(relnum, rel.get_r_offset()).c_str(),
1370               r_type);
1371       // gold_exit(false);
1372       break;
1373     }
1374 }
1375
1376 // Do a relocation in which we convert a TLS Initial-Exec to a
1377 // Local-Exec.
1378
1379 inline void
1380 Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
1381                                     size_t relnum,
1382                                     Output_segment* tls_segment,
1383                                     const elfcpp::Rel<32, false>& rel,
1384                                     unsigned int r_type,
1385                                     elfcpp::Elf_types<32>::Elf_Addr value,
1386                                     unsigned char* view,
1387                                     off_t view_size)
1388 {
1389   // We have to actually change the instructions, which means that we
1390   // need to examine the opcodes to figure out which instruction we
1391   // are looking at.
1392   if (r_type == elfcpp::R_386_TLS_IE)
1393     {
1394       // movl %gs:XX,%eax  ==>  movl $YY,%eax
1395       // movl %gs:XX,%reg  ==>  movl $YY,%reg
1396       // addl %gs:XX,%reg  ==>  addl $YY,%reg
1397       Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, -1);
1398       Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, 4);
1399
1400       unsigned char op1 = view[-1];
1401       if (op1 == 0xa1)
1402         {
1403           // movl XX,%eax  ==>  movl $YY,%eax
1404           view[-1] = 0xb8;
1405         }
1406       else
1407         {
1408           Target_i386::Relocate::check_range(relinfo, relnum, rel,
1409                                              view_size, -2);
1410
1411           unsigned char op2 = view[-2];
1412           if (op2 == 0x8b)
1413             {
1414               // movl XX,%reg  ==>  movl $YY,%reg
1415               Target_i386::Relocate::check_tls(relinfo, relnum, rel,
1416                                                (op1 & 0xc7) == 0x05);
1417               view[-2] = 0xc7;
1418               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1419             }
1420           else if (op2 == 0x03)
1421             {
1422               // addl XX,%reg  ==>  addl $YY,%reg
1423               Target_i386::Relocate::check_tls(relinfo, relnum, rel,
1424                                                (op1 & 0xc7) == 0x05);
1425               view[-2] = 0x81;
1426               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1427             }
1428           else
1429             Target_i386::Relocate::check_tls(relinfo, relnum, rel, 0);
1430         }
1431     }
1432   else
1433     {
1434       // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1435       // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1436       // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1437       Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, -2);
1438       Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, 4);
1439
1440       unsigned char op1 = view[-1];
1441       unsigned char op2 = view[-2];
1442       Target_i386::Relocate::check_tls(relinfo, relnum, rel,
1443                                        (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
1444       if (op2 == 0x8b)
1445         {
1446           // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1447           view[-2] = 0xc7;
1448           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1449         }
1450       else if (op2 == 0x2b)
1451         {
1452           // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1453           view[-2] = 0x81;
1454           view[-1] = 0xe8 | ((op1 >> 3) & 7);
1455         }
1456       else if (op2 == 0x03)
1457         {
1458           // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1459           view[-2] = 0x81;
1460           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1461         }
1462       else
1463         Target_i386::Relocate::check_tls(relinfo, relnum, rel, 0);
1464     }
1465
1466   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1467   if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
1468     value = - value;
1469
1470   Relocate_functions<32, false>::rel32(view, value);
1471 }
1472
1473 // Do a relocation in which we convert a TLS Global-Dynamic to a
1474 // Local-Exec.
1475
1476 inline void
1477 Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
1478                                     size_t relnum,
1479                                     Output_segment* tls_segment,
1480                                     const elfcpp::Rel<32, false>& rel,
1481                                     unsigned int,
1482                                     elfcpp::Elf_types<32>::Elf_Addr value,
1483                                     unsigned char* view,
1484                                     off_t view_size)
1485 {
1486   // leal foo(,%reg,1),%eax; call ___tls_get_addr
1487   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1488   // leal foo(%reg),%eax; call ___tls_get_addr
1489   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1490
1491   Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, -2);
1492   Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, 9);
1493
1494   unsigned char op1 = view[-1];
1495   unsigned char op2 = view[-2];
1496
1497   Target_i386::Relocate::check_tls(relinfo, relnum, rel,
1498                                    op2 == 0x8d || op2 == 0x04);
1499   Target_i386::Relocate::check_tls(relinfo, relnum, rel,
1500                                    view[4] == 0xe8);
1501
1502   int roff = 5;
1503
1504   if (op2 == 0x04)
1505     {
1506       Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, -3);
1507       Target_i386::Relocate::check_tls(relinfo, relnum, rel,
1508                                        view[-3] == 0x8d);
1509       Target_i386::Relocate::check_tls(relinfo, relnum, rel,
1510                                        ((op1 & 0xc7) == 0x05
1511                                         && op1 != (4 << 3)));
1512       memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1513     }
1514   else
1515     {
1516       Target_i386::Relocate::check_tls(relinfo, relnum, rel,
1517                                        (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1518       if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
1519           && view[9] == 0x90)
1520         {
1521           // There is a trailing nop.  Use the size byte subl.
1522           memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1523           roff = 6;
1524         }
1525       else
1526         {
1527           // Use the five byte subl.
1528           memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1529         }
1530     }
1531
1532   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1533   Relocate_functions<32, false>::rel32(view + roff, value);
1534
1535   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1536   // We can skip it.
1537   this->skip_call_tls_get_addr_ = true;
1538 }
1539
1540 // Do a relocation in which we convert a TLS Local-Dynamic to a
1541 // Local-Exec.
1542
1543 inline void
1544 Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
1545                                     size_t relnum,
1546                                     Output_segment*,
1547                                     const elfcpp::Rel<32, false>& rel,
1548                                     unsigned int,
1549                                     elfcpp::Elf_types<32>::Elf_Addr,
1550                                     unsigned char* view,
1551                                     off_t view_size)
1552 {
1553   // leal foo(%reg), %eax; call ___tls_get_addr
1554   // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
1555
1556   Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, -2);
1557   Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, 9);
1558
1559   // FIXME: Does this test really always pass?
1560   Target_i386::Relocate::check_tls(relinfo, relnum, rel,
1561                                    view[-2] == 0x8d && view[-1] == 0x83);
1562
1563   Target_i386::Relocate::check_tls(relinfo, relnum, rel,
1564                                    view[4] == 0xe8);
1565
1566   memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
1567
1568   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1569   // We can skip it.
1570   this->skip_call_tls_get_addr_ = true;
1571 }
1572
1573 // Check the range for a TLS relocation.
1574
1575 inline void
1576 Target_i386::Relocate::check_range(const Relocate_info<32, false>* relinfo,
1577                                    size_t relnum,
1578                                    const elfcpp::Rel<32, false>& rel,
1579                                    off_t view_size, off_t off)
1580 {
1581   off_t offset = rel.get_r_offset() + off;
1582   if (offset < 0 || offset > view_size)
1583     {
1584       fprintf(stderr, _("%s: %s: TLS relocation out of range\n"),
1585               program_name,
1586               relinfo->location(relnum, rel.get_r_offset()).c_str());
1587       gold_exit(false);
1588     }
1589 }
1590
1591 // Check the validity of a TLS relocation.  This is like assert.
1592
1593 inline void
1594 Target_i386::Relocate::check_tls(const Relocate_info<32, false>* relinfo,
1595                                  size_t relnum,
1596                                  const elfcpp::Rel<32, false>& rel,
1597                                  bool valid)
1598 {
1599   if (!valid)
1600     {
1601       fprintf(stderr,
1602               _("%s: %s: TLS relocation against invalid instruction\n"),
1603               program_name,
1604               relinfo->location(relnum, rel.get_r_offset()).c_str());
1605       gold_exit(false);
1606     }
1607 }
1608
1609 // Relocate section data.
1610
1611 void
1612 Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
1613                               unsigned int sh_type,
1614                               const unsigned char* prelocs,
1615                               size_t reloc_count,
1616                               unsigned char* view,
1617                               elfcpp::Elf_types<32>::Elf_Addr address,
1618                               off_t view_size)
1619 {
1620   gold_assert(sh_type == elfcpp::SHT_REL);
1621
1622   gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
1623                          Target_i386::Relocate>(
1624     relinfo,
1625     this,
1626     prelocs,
1627     reloc_count,
1628     view,
1629     address,
1630     view_size);
1631 }
1632
1633 // Return the value to use for a dynamic which requires special
1634 // treatment.  This is how we support equality comparisons of function
1635 // pointers across shared library boundaries, as described in the
1636 // processor specific ABI supplement.
1637
1638 uint64_t
1639 Target_i386::do_dynsym_value(const Symbol* gsym) const
1640 {
1641   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1642   return this->plt_section()->address() + gsym->plt_offset();
1643 }
1644
1645 // Return a string used to fill a code section with nops to take up
1646 // the specified length.
1647
1648 std::string
1649 Target_i386::do_code_fill(off_t length)
1650 {
1651   if (length >= 16)
1652     {
1653       // Build a jmp instruction to skip over the bytes.
1654       unsigned char jmp[5];
1655       jmp[0] = 0xe9;
1656       elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
1657       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1658               + std::string(length - 5, '\0'));
1659     }
1660
1661   // Nop sequences of various lengths.
1662   const char nop1[1] = { 0x90 };                   // nop
1663   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1664   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1665   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1666   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1667                          0x00 };                   // leal 0(%esi,1),%esi
1668   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1669                          0x00, 0x00 };
1670   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1671                          0x00, 0x00, 0x00 };
1672   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1673                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1674   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1675                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1676                          0x00 };
1677   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1678                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1679                            0x00, 0x00 };
1680   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1681                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1682                            0x00, 0x00, 0x00 };
1683   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1684                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1685                            0x00, 0x00, 0x00, 0x00 };
1686   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1687                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1688                            0x27, 0x00, 0x00, 0x00,
1689                            0x00 };
1690   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1691                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1692                            0xbc, 0x27, 0x00, 0x00,
1693                            0x00, 0x00 };
1694   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1695                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1696                            0x90, 0x90, 0x90, 0x90,
1697                            0x90, 0x90, 0x90 };
1698
1699   const char* nops[16] = {
1700     NULL,
1701     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1702     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1703   };
1704
1705   return std::string(nops[length], length);
1706 }
1707
1708 // The selector for i386 object files.
1709
1710 class Target_selector_i386 : public Target_selector
1711 {
1712 public:
1713   Target_selector_i386()
1714     : Target_selector(elfcpp::EM_386, 32, false)
1715   { }
1716
1717   Target*
1718   recognize(int machine, int osabi, int abiversion);
1719
1720  private:
1721   Target_i386* target_;
1722 };
1723
1724 // Recognize an i386 object file when we already know that the machine
1725 // number is EM_386.
1726
1727 Target*
1728 Target_selector_i386::recognize(int, int, int)
1729 {
1730   if (this->target_ == NULL)
1731     this->target_ = new Target_i386();
1732   return this->target_;
1733 }
1734
1735 Target_selector_i386 target_selector_i386;
1736
1737 } // End anonymous namespace.