gold/i386.cc

   1 // i386.cc -- i386 target support for gold.
   2
   3 // Copyright 2006, 2007 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #include "gold.h"
  24
  25 #include <cstring>
  26
  27 #include "elfcpp.h"
  28 #include "parameters.h"
  29 #include "reloc.h"
  30 #include "i386.h"
  31 #include "object.h"
  32 #include "symtab.h"
  33 #include "layout.h"
  34 #include "output.h"
  35 #include "target.h"
  36 #include "target-reloc.h"
  37 #include "target-select.h"
  38 #include "tls.h"
  39
  40 namespace
  41 {
  42
  43 using namespace gold;
  44
  45 class Output_data_plt_i386;
  46
  47 // The i386 target class.
  48 // TLS info comes from
  49 //   http://people.redhat.com/drepper/tls.pdf
  50 //   http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
  51
  52 class Target_i386 : public Sized_target<32, false>
  53 {
  54  public:
  55   typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
  56
  57   Target_i386()
  58     : Sized_target<32, false>(&i386_info),
  59       got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
  60       copy_relocs_(NULL), dynbss_(NULL)
  61   { }
  62
  63   // Scan the relocations to look for symbol adjustments.
  64   void
  65   scan_relocs(const General_options& options,
  66               Symbol_table* symtab,
  67               Layout* layout,
  68               Sized_relobj<32, false>* object,
  69               unsigned int data_shndx,
  70               unsigned int sh_type,
  71               const unsigned char* prelocs,
  72               size_t reloc_count,
  73               size_t local_symbol_count,
  74               const unsigned char* plocal_symbols,
  75               Symbol** global_symbols);
  76
  77   // Finalize the sections.
  78   void
  79   do_finalize_sections(Layout*);
  80
  81   // Return the value to use for a dynamic which requires special
  82   // treatment.
  83   uint64_t
  84   do_dynsym_value(const Symbol*) const;
  85
  86   // Relocate a section.
  87   void
  88   relocate_section(const Relocate_info<32, false>*,
  89                    unsigned int sh_type,
  90                    const unsigned char* prelocs,
  91                    size_t reloc_count,
  92                    unsigned char* view,
  93                    elfcpp::Elf_types<32>::Elf_Addr view_address,
  94                    off_t view_size);
  95
  96   // Return a string used to fill a code section with nops.
  97   std::string
  98   do_code_fill(off_t length);
  99
 100  private:
 101   // The class which scans relocations.
 102   struct Scan
 103   {
 104     inline void
 105     local(const General_options& options, Symbol_table* symtab,
 106           Layout* layout, Target_i386* target,
 107           Sized_relobj<32, false>* object,
 108           unsigned int data_shndx,
 109           const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
 110           const elfcpp::Sym<32, false>& lsym);
 111
 112     inline void
 113     global(const General_options& options, Symbol_table* symtab,
 114            Layout* layout, Target_i386* target,
 115            Sized_relobj<32, false>* object,
 116            unsigned int data_shndx,
 117            const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
 118            Symbol* gsym);
 119
 120     static void
 121     unsupported_reloc_local(Sized_relobj<32, false>*, unsigned int r_type);
 122
 123     static void
 124     unsupported_reloc_global(Sized_relobj<32, false>*, unsigned int r_type,
 125                              Symbol*);
 126   };
 127
 128   // The class which implements relocation.
 129   class Relocate
 130   {
 131    public:
 132     Relocate()
 133       : skip_call_tls_get_addr_(false),
 134         local_dynamic_type_(LOCAL_DYNAMIC_NONE)
 135     { }
 136
 137     ~Relocate()
 138     {
 139       if (this->skip_call_tls_get_addr_)
 140         {
 141           // FIXME: This needs to specify the location somehow.
 142           gold_error(_("missing expected TLS relocation"));
 143         }
 144     }
 145
 146     // Do a relocation.  Return false if the caller should not issue
 147     // any warnings about this relocation.
 148     inline bool
 149     relocate(const Relocate_info<32, false>*, Target_i386*, size_t relnum,
 150              const elfcpp::Rel<32, false>&,
 151              unsigned int r_type, const Sized_symbol<32>*,
 152              const Symbol_value<32>*,
 153              unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
 154              off_t);
 155
 156    private:
 157     // Do a TLS relocation.
 158     inline void
 159     relocate_tls(const Relocate_info<32, false>*, size_t relnum,
 160                  const elfcpp::Rel<32, false>&,
 161                  unsigned int r_type, const Sized_symbol<32>*,
 162                  const Symbol_value<32>*,
 163                  unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, off_t);
 164
 165     // Do a TLS Initial-Exec to Local-Exec transition.
 166     static inline void
 167     tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum,
 168                  Output_segment* tls_segment,
 169                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 170                  elfcpp::Elf_types<32>::Elf_Addr value,
 171                  unsigned char* view,
 172                  off_t view_size);
 173
 174     // Do a TLS General-Dynamic to Local-Exec transition.
 175     inline void
 176     tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
 177                  Output_segment* tls_segment,
 178                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 179                  elfcpp::Elf_types<32>::Elf_Addr value,
 180                  unsigned char* view,
 181                  off_t view_size);
 182
 183     // Do a TLS Local-Dynamic to Local-Exec transition.
 184     inline void
 185     tls_ld_to_le(const Relocate_info<32, false>*, size_t relnum,
 186                  Output_segment* tls_segment,
 187                  const elfcpp::Rel<32, false>&, unsigned int r_type,
 188                  elfcpp::Elf_types<32>::Elf_Addr value,
 189                  unsigned char* view,
 190                  off_t view_size);
 191
 192     // We need to keep track of which type of local dynamic relocation
 193     // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
 194     enum Local_dynamic_type
 195     {
 196       LOCAL_DYNAMIC_NONE,
 197       LOCAL_DYNAMIC_SUN,
 198       LOCAL_DYNAMIC_GNU
 199     };
 200
 201     // This is set if we should skip the next reloc, which should be a
 202     // PLT32 reloc against ___tls_get_addr.
 203     bool skip_call_tls_get_addr_;
 204     // The type of local dynamic relocation we have seen in the section
 205     // being relocated, if any.
 206     Local_dynamic_type local_dynamic_type_;
 207   };
 208
 209   // Adjust TLS relocation type based on the options and whether this
 210   // is a local symbol.
 211   static tls::Tls_optimization
 212   optimize_tls_reloc(bool is_final, int r_type);
 213
 214   // Get the GOT section, creating it if necessary.
 215   Output_data_got<32, false>*
 216   got_section(Symbol_table*, Layout*);
 217
 218   // Create a PLT entry for a global symbol.
 219   void
 220   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 221
 222   // Get the PLT section.
 223   const Output_data_plt_i386*
 224   plt_section() const
 225   {
 226     gold_assert(this->plt_ != NULL);
 227     return this->plt_;
 228   }
 229
 230   // Get the dynamic reloc section, creating it if necessary.
 231   Reloc_section*
 232   rel_dyn_section(Layout*);
 233
 234   // Copy a relocation against a global symbol.
 235   void
 236   copy_reloc(const General_options*, Symbol_table*, Layout*,
 237              Sized_relobj<32, false>*, unsigned int,
 238              Symbol*, const elfcpp::Rel<32, false>&);
 239
 240   // Information about this specific target which we pass to the
 241   // general Target structure.
 242   static const Target::Target_info i386_info;
 243
 244   // The GOT section.
 245   Output_data_got<32, false>* got_;
 246   // The PLT section.
 247   Output_data_plt_i386* plt_;
 248   // The GOT PLT section.
 249   Output_data_space* got_plt_;
 250   // The dynamic reloc section.
 251   Reloc_section* rel_dyn_;
 252   // Relocs saved to avoid a COPY reloc.
 253   Copy_relocs<32, false>* copy_relocs_;
 254   // Space for variables copied with a COPY reloc.
 255   Output_data_space* dynbss_;
 256 };
 257
 258 const Target::Target_info Target_i386::i386_info =
 259 {
 260   32,                   // size
 261   false,                // is_big_endian
 262   elfcpp::EM_386,       // machine_code
 263   false,                // has_make_symbol
 264   false,                // has_resolve
 265   true,                 // has_code_fill
 266   "/usr/lib/libc.so.1", // dynamic_linker
 267   0x08048000,           // default_text_segment_address
 268   0x1000,               // abi_pagesize
 269   0x1000                // common_pagesize
 270 };
 271
 272 // Get the GOT section, creating it if necessary.
 273
 274 Output_data_got<32, false>*
 275 Target_i386::got_section(Symbol_table* symtab, Layout* layout)
 276 {
 277   if (this->got_ == NULL)
 278     {
 279       gold_assert(symtab != NULL && layout != NULL);
 280
 281       this->got_ = new Output_data_got<32, false>();
 282
 283       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 284                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 285                                       this->got_);
 286
 287       // The old GNU linker creates a .got.plt section.  We just
 288       // create another set of data in the .got section.  Note that we
 289       // always create a PLT if we create a GOT, although the PLT
 290       // might be empty.
 291       this->got_plt_ = new Output_data_space(4);
 292       layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
 293                                       elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
 294                                       this->got_plt_);
 295
 296       // The first three entries are reserved.
 297       this->got_plt_->set_space_size(3 * 4);
 298
 299       // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
 300       symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
 301                                     this->got_plt_,
 302                                     0, 0, elfcpp::STT_OBJECT,
 303                                     elfcpp::STB_LOCAL,
 304                                     elfcpp::STV_HIDDEN, 0,
 305                                     false, false);
 306     }
 307
 308   return this->got_;
 309 }
 310
 311 // Get the dynamic reloc section, creating it if necessary.
 312
 313 Target_i386::Reloc_section*
 314 Target_i386::rel_dyn_section(Layout* layout)
 315 {
 316   if (this->rel_dyn_ == NULL)
 317     {
 318       gold_assert(layout != NULL);
 319       this->rel_dyn_ = new Reloc_section();
 320       layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
 321                                       elfcpp::SHF_ALLOC, this->rel_dyn_);
 322     }
 323   return this->rel_dyn_;
 324 }
 325
 326 // A class to handle the PLT data.
 327
 328 class Output_data_plt_i386 : public Output_section_data
 329 {
 330  public:
 331   typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
 332
 333   Output_data_plt_i386(Layout*, Output_data_space*);
 334
 335   // Add an entry to the PLT.
 336   void
 337   add_entry(Symbol* gsym);
 338
 339   // Return the .rel.plt section data.
 340   const Reloc_section*
 341   rel_plt() const
 342   { return this->rel_; }
 343
 344  protected:
 345   void
 346   do_adjust_output_section(Output_section* os);
 347
 348  private:
 349   // The size of an entry in the PLT.
 350   static const int plt_entry_size = 16;
 351
 352   // The first entry in the PLT for an executable.
 353   static unsigned char exec_first_plt_entry[plt_entry_size];
 354
 355   // The first entry in the PLT for a shared object.
 356   static unsigned char dyn_first_plt_entry[plt_entry_size];
 357
 358   // Other entries in the PLT for an executable.
 359   static unsigned char exec_plt_entry[plt_entry_size];
 360
 361   // Other entries in the PLT for a shared object.
 362   static unsigned char dyn_plt_entry[plt_entry_size];
 363
 364   // Set the final size.
 365   void
 366   do_set_address(uint64_t, off_t)
 367   { this->set_data_size((this->count_ + 1) * plt_entry_size); }
 368
 369   // Write out the PLT data.
 370   void
 371   do_write(Output_file*);
 372
 373   // The reloc section.
 374   Reloc_section* rel_;
 375   // The .got.plt section.
 376   Output_data_space* got_plt_;
 377   // The number of PLT entries.
 378   unsigned int count_;
 379 };
 380
 381 // Create the PLT section.  The ordinary .got section is an argument,
 382 // since we need to refer to the start.  We also create our own .got
 383 // section just for PLT entries.
 384
 385 Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
 386                                            Output_data_space* got_plt)
 387   : Output_section_data(4), got_plt_(got_plt), count_(0)
 388 {
 389   this->rel_ = new Reloc_section();
 390   layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
 391                                   elfcpp::SHF_ALLOC, this->rel_);
 392 }
 393
 394 void
 395 Output_data_plt_i386::do_adjust_output_section(Output_section* os)
 396 {
 397   // UnixWare sets the entsize of .plt to 4, and so does the old GNU
 398   // linker, and so do we.
 399   os->set_entsize(4);
 400 }
 401
 402 // Add an entry to the PLT.
 403
 404 void
 405 Output_data_plt_i386::add_entry(Symbol* gsym)
 406 {
 407   gold_assert(!gsym->has_plt_offset());
 408
 409   // Note that when setting the PLT offset we skip the initial
 410   // reserved PLT entry.
 411   gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
 412
 413   ++this->count_;
 414
 415   off_t got_offset = this->got_plt_->data_size();
 416
 417   // Every PLT entry needs a GOT entry which points back to the PLT
 418   // entry (this will be changed by the dynamic linker, normally
 419   // lazily when the function is called).
 420   this->got_plt_->set_space_size(got_offset + 4);
 421
 422   // Every PLT entry needs a reloc.
 423   gsym->set_needs_dynsym_entry();
 424   this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_,
 425                          got_offset);
 426
 427   // Note that we don't need to save the symbol.  The contents of the
 428   // PLT are independent of which symbols are used.  The symbols only
 429   // appear in the relocations.
 430 }
 431
 432 // The first entry in the PLT for an executable.
 433
 434 unsigned char Output_data_plt_i386::exec_first_plt_entry[plt_entry_size] =
 435 {
 436   0xff, 0x35,   // pushl contents of memory address
 437   0, 0, 0, 0,   // replaced with address of .got + 4
 438   0xff, 0x25,   // jmp indirect
 439   0, 0, 0, 0,   // replaced with address of .got + 8
 440   0, 0, 0, 0    // unused
 441 };
 442
 443 // The first entry in the PLT for a shared object.
 444
 445 unsigned char Output_data_plt_i386::dyn_first_plt_entry[plt_entry_size] =
 446 {
 447   0xff, 0xb3, 4, 0, 0, 0,       // pushl 4(%ebx)
 448   0xff, 0xa3, 8, 0, 0, 0,       // jmp *8(%ebx)
 449   0, 0, 0, 0                    // unused
 450 };
 451
 452 // Subsequent entries in the PLT for an executable.
 453
 454 unsigned char Output_data_plt_i386::exec_plt_entry[plt_entry_size] =
 455 {
 456   0xff, 0x25,   // jmp indirect
 457   0, 0, 0, 0,   // replaced with address of symbol in .got
 458   0x68,         // pushl immediate
 459   0, 0, 0, 0,   // replaced with offset into relocation table
 460   0xe9,         // jmp relative
 461   0, 0, 0, 0    // replaced with offset to start of .plt
 462 };
 463
 464 // Subsequent entries in the PLT for a shared object.
 465
 466 unsigned char Output_data_plt_i386::dyn_plt_entry[plt_entry_size] =
 467 {
 468   0xff, 0xa3,   // jmp *offset(%ebx)
 469   0, 0, 0, 0,   // replaced with offset of symbol in .got
 470   0x68,         // pushl immediate
 471   0, 0, 0, 0,   // replaced with offset into relocation table
 472   0xe9,         // jmp relative
 473   0, 0, 0, 0    // replaced with offset to start of .plt
 474 };
 475
 476 // Write out the PLT.  This uses the hand-coded instructions above,
 477 // and adjusts them as needed.  This is all specified by the i386 ELF
 478 // Processor Supplement.
 479
 480 void
 481 Output_data_plt_i386::do_write(Output_file* of)
 482 {
 483   const off_t offset = this->offset();
 484   const off_t oview_size = this->data_size();
 485   unsigned char* const oview = of->get_output_view(offset, oview_size);
 486
 487   const off_t got_file_offset = this->got_plt_->offset();
 488   const off_t got_size = this->got_plt_->data_size();
 489   unsigned char* const got_view = of->get_output_view(got_file_offset,
 490                                                       got_size);
 491
 492   unsigned char* pov = oview;
 493
 494   elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
 495   elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
 496
 497   if (parameters->output_is_shared())
 498     memcpy(pov, dyn_first_plt_entry, plt_entry_size);
 499   else
 500     {
 501       memcpy(pov, exec_first_plt_entry, plt_entry_size);
 502       elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
 503       elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
 504     }
 505   pov += plt_entry_size;
 506
 507   unsigned char* got_pov = got_view;
 508
 509   memset(got_pov, 0, 12);
 510   got_pov += 12;
 511
 512   const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
 513
 514   unsigned int plt_offset = plt_entry_size;
 515   unsigned int plt_rel_offset = 0;
 516   unsigned int got_offset = 12;
 517   const unsigned int count = this->count_;
 518   for (unsigned int i = 0;
 519        i < count;
 520        ++i,
 521          pov += plt_entry_size,
 522          got_pov += 4,
 523          plt_offset += plt_entry_size,
 524          plt_rel_offset += rel_size,
 525          got_offset += 4)
 526     {
 527       // Set and adjust the PLT entry itself.
 528
 529       if (parameters->output_is_shared())
 530         {
 531           memcpy(pov, dyn_plt_entry, plt_entry_size);
 532           elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
 533         }
 534       else
 535         {
 536           memcpy(pov, exec_plt_entry, plt_entry_size);
 537           elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
 538                                                       (got_address
 539                                                        + got_offset));
 540         }
 541
 542       elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
 543       elfcpp::Swap<32, false>::writeval(pov + 12,
 544                                         - (plt_offset + plt_entry_size));
 545
 546       // Set the entry in the GOT.
 547       elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6);
 548     }
 549
 550   gold_assert(pov - oview == oview_size);
 551   gold_assert(got_pov - got_view == got_size);
 552
 553   of->write_output_view(offset, oview_size, oview);
 554   of->write_output_view(got_file_offset, got_size, got_view);
 555 }
 556
 557 // Create a PLT entry for a global symbol.
 558
 559 void
 560 Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym)
 561 {
 562   if (gsym->has_plt_offset())
 563     return;
 564
 565   if (this->plt_ == NULL)
 566     {
 567       // Create the GOT sections first.
 568       this->got_section(symtab, layout);
 569
 570       this->plt_ = new Output_data_plt_i386(layout, this->got_plt_);
 571       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
 572                                       (elfcpp::SHF_ALLOC
 573                                        | elfcpp::SHF_EXECINSTR),
 574                                       this->plt_);
 575     }
 576
 577   this->plt_->add_entry(gsym);
 578 }
 579
 580 // Handle a relocation against a non-function symbol defined in a
 581 // dynamic object.  The traditional way to handle this is to generate
 582 // a COPY relocation to copy the variable at runtime from the shared
 583 // object into the executable's data segment.  However, this is
 584 // undesirable in general, as if the size of the object changes in the
 585 // dynamic object, the executable will no longer work correctly.  If
 586 // this relocation is in a writable section, then we can create a
 587 // dynamic reloc and the dynamic linker will resolve it to the correct
 588 // address at runtime.  However, we do not want do that if the
 589 // relocation is in a read-only section, as it would prevent the
 590 // readonly segment from being shared.  And if we have to eventually
 591 // generate a COPY reloc, then any dynamic relocations will be
 592 // useless.  So this means that if this is a writable section, we need
 593 // to save the relocation until we see whether we have to create a
 594 // COPY relocation for this symbol for any other relocation.
 595
 596 void
 597 Target_i386::copy_reloc(const General_options* options,
 598                         Symbol_table* symtab,
 599                         Layout* layout,
 600                         Sized_relobj<32, false>* object,
 601                         unsigned int data_shndx, Symbol* gsym,
 602                         const elfcpp::Rel<32, false>& rel)
 603 {
 604   Sized_symbol<32>* ssym;
 605   ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(32) (gsym
 606                                                         SELECT_SIZE(32));
 607
 608   if (!Copy_relocs<32, false>::need_copy_reloc(options, object,
 609                                                data_shndx, ssym))
 610     {
 611       // So far we do not need a COPY reloc.  Save this relocation.
 612       // If it turns out that we never need a COPY reloc for this
 613       // symbol, then we will emit the relocation.
 614       if (this->copy_relocs_ == NULL)
 615         this->copy_relocs_ = new Copy_relocs<32, false>();
 616       this->copy_relocs_->save(ssym, object, data_shndx, rel);
 617     }
 618   else
 619     {
 620       // Allocate space for this symbol in the .bss section.
 621
 622       elfcpp::Elf_types<32>::Elf_WXword symsize = ssym->symsize();
 623
 624       // There is no defined way to determine the required alignment
 625       // of the symbol.  We pick the alignment based on the size.  We
 626       // set an arbitrary maximum of 256.
 627       unsigned int align;
 628       for (align = 1; align < 512; align <<= 1)
 629         if ((symsize & align) != 0)
 630           break;
 631
 632       if (this->dynbss_ == NULL)
 633         {
 634           this->dynbss_ = new Output_data_space(align);
 635           layout->add_output_section_data(".bss",
 636                                           elfcpp::SHT_NOBITS,
 637                                           (elfcpp::SHF_ALLOC
 638                                            | elfcpp::SHF_WRITE),
 639                                           this->dynbss_);
 640         }
 641
 642       Output_data_space* dynbss = this->dynbss_;
 643
 644       if (align > dynbss->addralign())
 645         dynbss->set_space_alignment(align);
 646
 647       off_t dynbss_size = dynbss->data_size();
 648       dynbss_size = align_address(dynbss_size, align);
 649       off_t offset = dynbss_size;
 650       dynbss->set_space_size(dynbss_size + symsize);
 651
 652       symtab->define_with_copy_reloc(this, ssym, dynbss, offset);
 653
 654       // Add the COPY reloc.
 655       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
 656       rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset);
 657     }
 658 }
 659
 660 // Optimize the TLS relocation type based on what we know about the
 661 // symbol.  IS_FINAL is true if the final address of this symbol is
 662 // known at link time.
 663
 664 tls::Tls_optimization
 665 Target_i386::optimize_tls_reloc(bool is_final, int r_type)
 666 {
 667   // If we are generating a shared library, then we can't do anything
 668   // in the linker.
 669   if (parameters->output_is_shared())
 670     return tls::TLSOPT_NONE;
 671
 672   switch (r_type)
 673     {
 674     case elfcpp::R_386_TLS_GD:
 675     case elfcpp::R_386_TLS_GOTDESC:
 676     case elfcpp::R_386_TLS_DESC_CALL:
 677       // These are General-Dynamic which permits fully general TLS
 678       // access.  Since we know that we are generating an executable,
 679       // we can convert this to Initial-Exec.  If we also know that
 680       // this is a local symbol, we can further switch to Local-Exec.
 681       if (is_final)
 682         return tls::TLSOPT_TO_LE;
 683       return tls::TLSOPT_TO_IE;
 684
 685     case elfcpp::R_386_TLS_LDM:
 686       // This is Local-Dynamic, which refers to a local symbol in the
 687       // dynamic TLS block.  Since we know that we generating an
 688       // executable, we can switch to Local-Exec.
 689       return tls::TLSOPT_TO_LE;
 690
 691     case elfcpp::R_386_TLS_LDO_32:
 692       // Another type of Local-Dynamic relocation.
 693       return tls::TLSOPT_TO_LE;
 694
 695     case elfcpp::R_386_TLS_IE:
 696     case elfcpp::R_386_TLS_GOTIE:
 697     case elfcpp::R_386_TLS_IE_32:
 698       // These are Initial-Exec relocs which get the thread offset
 699       // from the GOT.  If we know that we are linking against the
 700       // local symbol, we can switch to Local-Exec, which links the
 701       // thread offset into the instruction.
 702       if (is_final)
 703         return tls::TLSOPT_TO_LE;
 704       return tls::TLSOPT_NONE;
 705
 706     case elfcpp::R_386_TLS_LE:
 707     case elfcpp::R_386_TLS_LE_32:
 708       // When we already have Local-Exec, there is nothing further we
 709       // can do.
 710       return tls::TLSOPT_NONE;
 711
 712     default:
 713       gold_unreachable();
 714     }
 715 }
 716
 717 // Report an unsupported relocation against a local symbol.
 718
 719 void
 720 Target_i386::Scan::unsupported_reloc_local(Sized_relobj<32, false>* object,
 721                                            unsigned int r_type)
 722 {
 723   gold_error(_("%s: unsupported reloc %u against local symbol"),
 724              object->name().c_str(), r_type);
 725 }
 726
 727 // Scan a relocation for a local symbol.
 728
 729 inline void
 730 Target_i386::Scan::local(const General_options&,
 731                          Symbol_table* symtab,
 732                          Layout* layout,
 733                          Target_i386* target,
 734                          Sized_relobj<32, false>* object,
 735                          unsigned int data_shndx,
 736                          const elfcpp::Rel<32, false>& reloc,
 737                          unsigned int r_type,
 738                          const elfcpp::Sym<32, false>&)
 739 {
 740   switch (r_type)
 741     {
 742     case elfcpp::R_386_NONE:
 743     case elfcpp::R_386_GNU_VTINHERIT:
 744     case elfcpp::R_386_GNU_VTENTRY:
 745       break;
 746
 747     case elfcpp::R_386_32:
 748     case elfcpp::R_386_16:
 749     case elfcpp::R_386_8:
 750       // If building a shared library (or a position-independent
 751       // executable), we need to create a dynamic relocation for
 752       // this location. The relocation applied at link time will
 753       // apply the link-time value, so we flag the location with
 754       // an R_386_RELATIVE relocation so the dynamic loader can
 755       // relocate it easily.
 756       if (parameters->output_is_position_independent())
 757         {
 758           Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 759           rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE, data_shndx,
 760                              reloc.get_r_offset());
 761         }
 762       break;
 763
 764     case elfcpp::R_386_PC32:
 765     case elfcpp::R_386_PC16:
 766     case elfcpp::R_386_PC8:
 767       break;
 768
 769     case elfcpp::R_386_PLT32:
 770       // Since we know this is a local symbol, we can handle this as a
 771       // PC32 reloc.
 772       break;
 773
 774     case elfcpp::R_386_GOTOFF:
 775     case elfcpp::R_386_GOTPC:
 776       // We need a GOT section.
 777       target->got_section(symtab, layout);
 778       break;
 779
 780     case elfcpp::R_386_GOT32:
 781       {
 782         // The symbol requires a GOT entry.
 783         Output_data_got<32, false>* got = target->got_section(symtab, layout);
 784         unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
 785         if (got->add_local(object, r_sym))
 786           {
 787             // If we are generating a shared object, we need to add a
 788             // dynamic RELATIVE relocation for this symbol.
 789             if (parameters->output_is_position_independent())
 790               {
 791                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 792                 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE,
 793                                    data_shndx, reloc.get_r_offset());
 794               }
 795           }
 796       }
 797       break;
 798
 799       // These are relocations which should only be seen by the
 800       // dynamic linker, and should never be seen here.
 801     case elfcpp::R_386_COPY:
 802     case elfcpp::R_386_GLOB_DAT:
 803     case elfcpp::R_386_JUMP_SLOT:
 804     case elfcpp::R_386_RELATIVE:
 805     case elfcpp::R_386_TLS_TPOFF:
 806     case elfcpp::R_386_TLS_DTPMOD32:
 807     case elfcpp::R_386_TLS_DTPOFF32:
 808     case elfcpp::R_386_TLS_TPOFF32:
 809     case elfcpp::R_386_TLS_DESC:
 810       gold_error(_("%s: unexpected reloc %u in object file"),
 811                  object->name().c_str(), r_type);
 812       break;
 813
 814       // These are initial TLS relocs, which are expected when
 815       // linking.
 816     case elfcpp::R_386_TLS_IE:
 817     case elfcpp::R_386_TLS_GOTIE:
 818     case elfcpp::R_386_TLS_LE:
 819     case elfcpp::R_386_TLS_GD:
 820     case elfcpp::R_386_TLS_LDM:
 821     case elfcpp::R_386_TLS_LDO_32:
 822     case elfcpp::R_386_TLS_IE_32:
 823     case elfcpp::R_386_TLS_LE_32:
 824     case elfcpp::R_386_TLS_GOTDESC:
 825     case elfcpp::R_386_TLS_DESC_CALL:
 826       {
 827         bool output_is_shared = parameters->output_is_shared();
 828         const tls::Tls_optimization optimized_type
 829             = Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
 830         switch (r_type)
 831           {
 832           case elfcpp::R_386_TLS_LE:
 833           case elfcpp::R_386_TLS_LE_32:
 834             // FIXME: If generating a shared object, we need to copy
 835             // this relocation into the object.
 836             gold_assert(!output_is_shared);
 837             break;
 838
 839           case elfcpp::R_386_TLS_IE:
 840           case elfcpp::R_386_TLS_IE_32:
 841           case elfcpp::R_386_TLS_GOTIE:
 842             // FIXME: If not relaxing to LE, we need to generate a
 843             // TPOFF or TPOFF32 reloc.
 844             if (optimized_type != tls::TLSOPT_TO_LE)
 845               unsupported_reloc_local(object, r_type);
 846             break;
 847
 848           case elfcpp::R_386_TLS_LDM:
 849             // FIXME: If not relaxing to LE, we need to generate a
 850             // DTPMOD32 reloc.
 851             if (optimized_type != tls::TLSOPT_TO_LE)
 852               unsupported_reloc_local(object, r_type);
 853             break;
 854
 855           case elfcpp::R_386_TLS_LDO_32:
 856             break;
 857
 858           case elfcpp::R_386_TLS_GD:
 859           case elfcpp::R_386_TLS_GOTDESC:
 860           case elfcpp::R_386_TLS_DESC_CALL:
 861             // FIXME: If not relaxing to LE, we need to generate
 862             // DTPMOD32 and DTPOFF32 relocs.
 863             if (optimized_type != tls::TLSOPT_TO_LE)
 864               unsupported_reloc_local(object, r_type);
 865             break;
 866
 867           default:
 868             gold_unreachable();
 869           }
 870       }
 871       break;
 872
 873     case elfcpp::R_386_32PLT:
 874     case elfcpp::R_386_TLS_GD_32:
 875     case elfcpp::R_386_TLS_GD_PUSH:
 876     case elfcpp::R_386_TLS_GD_CALL:
 877     case elfcpp::R_386_TLS_GD_POP:
 878     case elfcpp::R_386_TLS_LDM_32:
 879     case elfcpp::R_386_TLS_LDM_PUSH:
 880     case elfcpp::R_386_TLS_LDM_CALL:
 881     case elfcpp::R_386_TLS_LDM_POP:
 882     case elfcpp::R_386_USED_BY_INTEL_200:
 883     default:
 884       unsupported_reloc_local(object, r_type);
 885       break;
 886     }
 887 }
 888
 889 // Report an unsupported relocation against a global symbol.
 890
 891 void
 892 Target_i386::Scan::unsupported_reloc_global(Sized_relobj<32, false>* object,
 893                                             unsigned int r_type,
 894                                             Symbol* gsym)
 895 {
 896   gold_error(_("%s: unsupported reloc %u against global symbol %s"),
 897              object->name().c_str(), r_type, gsym->name());
 898 }
 899
 900 // Scan a relocation for a global symbol.
 901
 902 inline void
 903 Target_i386::Scan::global(const General_options& options,
 904                           Symbol_table* symtab,
 905                           Layout* layout,
 906                           Target_i386* target,
 907                           Sized_relobj<32, false>* object,
 908                           unsigned int data_shndx,
 909                           const elfcpp::Rel<32, false>& reloc,
 910                           unsigned int r_type,
 911                           Symbol* gsym)
 912 {
 913   switch (r_type)
 914     {
 915     case elfcpp::R_386_NONE:
 916     case elfcpp::R_386_GNU_VTINHERIT:
 917     case elfcpp::R_386_GNU_VTENTRY:
 918       break;
 919
 920     case elfcpp::R_386_32:
 921     case elfcpp::R_386_PC32:
 922     case elfcpp::R_386_16:
 923     case elfcpp::R_386_PC16:
 924     case elfcpp::R_386_8:
 925     case elfcpp::R_386_PC8:
 926       if (gsym->is_from_dynobj()
 927           || (parameters->output_is_shared()
 928               && gsym->is_preemptible()))
 929         {
 930           // (a) This symbol is defined in a dynamic object.  If it is a
 931           // function, we make a PLT entry.  Otherwise we need to
 932           // either generate a COPY reloc or copy this reloc.
 933           // (b) We are building a shared object and this symbol is
 934           // preemptible. If it is a function, we make a PLT entry.
 935           // Otherwise, we copy the reloc. We do not make COPY relocs
 936           // in shared objects.
 937           if (gsym->type() == elfcpp::STT_FUNC)
 938             {
 939               target->make_plt_entry(symtab, layout, gsym);
 940
 941               // If this is not a PC relative reference, then we may
 942               // be taking the address of the function.  In that case
 943               // we need to set the entry in the dynamic symbol table
 944               // to the address of the PLT entry.
 945               if (r_type != elfcpp::R_386_PC32
 946                   && r_type != elfcpp::R_386_PC16
 947                   && r_type != elfcpp::R_386_PC8
 948                   && gsym->is_from_dynobj())
 949                 gsym->set_needs_dynsym_value();
 950             }
 951           else if (parameters->output_is_shared())
 952             {
 953               Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 954               rel_dyn->add_global(gsym, r_type, object, data_shndx,
 955                                   reloc.get_r_offset());
 956             }
 957           else
 958             target->copy_reloc(&options, symtab, layout, object, data_shndx,
 959                                gsym, reloc);
 960         }
 961
 962       break;
 963
 964     case elfcpp::R_386_GOT32:
 965       {
 966         // The symbol requires a GOT entry.
 967         Output_data_got<32, false>* got = target->got_section(symtab, layout);
 968         if (got->add_global(gsym))
 969           {
 970             // If this symbol is not fully resolved, we need to add a
 971             // dynamic relocation for it.
 972             if (!gsym->final_value_is_known())
 973               {
 974                 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
 975                 rel_dyn->add_global(gsym, elfcpp::R_386_GLOB_DAT, got,
 976                                     gsym->got_offset());
 977               }
 978           }
 979       }
 980       break;
 981
 982     case elfcpp::R_386_PLT32:
 983       // If the symbol is fully resolved, this is just a PC32 reloc.
 984       // Otherwise we need a PLT entry.
 985       if (gsym->final_value_is_known())
 986         break;
 987       // If building a shared library, we can also skip the PLT entry
 988       // if the symbol is defined in the output file and is protected
 989       // or hidden.
 990       if (gsym->is_defined()
 991           && !gsym->is_from_dynobj()
 992           && !gsym->is_preemptible())
 993         break;
 994       target->make_plt_entry(symtab, layout, gsym);
 995       break;
 996
 997     case elfcpp::R_386_GOTOFF:
 998     case elfcpp::R_386_GOTPC:
 999       // We need a GOT section.
1000       target->got_section(symtab, layout);
1001       break;
1002
1003       // These are relocations which should only be seen by the
1004       // dynamic linker, and should never be seen here.
1005     case elfcpp::R_386_COPY:
1006     case elfcpp::R_386_GLOB_DAT:
1007     case elfcpp::R_386_JUMP_SLOT:
1008     case elfcpp::R_386_RELATIVE:
1009     case elfcpp::R_386_TLS_TPOFF:
1010     case elfcpp::R_386_TLS_DTPMOD32:
1011     case elfcpp::R_386_TLS_DTPOFF32:
1012     case elfcpp::R_386_TLS_TPOFF32:
1013     case elfcpp::R_386_TLS_DESC:
1014       gold_error(_("%s: unexpected reloc %u in object file"),
1015                  object->name().c_str(), r_type);
1016       break;
1017
1018       // These are initial tls relocs, which are expected when
1019       // linking.
1020     case elfcpp::R_386_TLS_IE:
1021     case elfcpp::R_386_TLS_GOTIE:
1022     case elfcpp::R_386_TLS_LE:
1023     case elfcpp::R_386_TLS_GD:
1024     case elfcpp::R_386_TLS_LDM:
1025     case elfcpp::R_386_TLS_LDO_32:
1026     case elfcpp::R_386_TLS_IE_32:
1027     case elfcpp::R_386_TLS_LE_32:
1028     case elfcpp::R_386_TLS_GOTDESC:
1029     case elfcpp::R_386_TLS_DESC_CALL:
1030       {
1031         const bool is_final = gsym->final_value_is_known();
1032         const tls::Tls_optimization optimized_type
1033             = Target_i386::optimize_tls_reloc(is_final, r_type);
1034         switch (r_type)
1035           {
1036           case elfcpp::R_386_TLS_LE:
1037           case elfcpp::R_386_TLS_LE_32:
1038             // FIXME: If generating a shared object, we need to copy
1039             // this relocation into the object.
1040             gold_assert(!parameters->output_is_shared());
1041             break;
1042
1043           case elfcpp::R_386_TLS_IE:
1044           case elfcpp::R_386_TLS_IE_32:
1045           case elfcpp::R_386_TLS_GOTIE:
1046             // FIXME: If not relaxing to LE, we need to generate a
1047             // TPOFF or TPOFF32 reloc.
1048             if (optimized_type != tls::TLSOPT_TO_LE)
1049               unsupported_reloc_global(object, r_type, gsym);
1050             break;
1051
1052           case elfcpp::R_386_TLS_LDM:
1053             // FIXME: If not relaxing to LE, we need to generate a
1054             // DTPMOD32 reloc.
1055             if (optimized_type != tls::TLSOPT_TO_LE)
1056               unsupported_reloc_global(object, r_type, gsym);
1057             break;
1058
1059           case elfcpp::R_386_TLS_LDO_32:
1060             break;
1061
1062           case elfcpp::R_386_TLS_GD:
1063           case elfcpp::R_386_TLS_GOTDESC:
1064           case elfcpp::R_386_TLS_DESC_CALL:
1065             // FIXME: If not relaxing to LE, we need to generate
1066             // DTPMOD32 and DTPOFF32 relocs.
1067             if (optimized_type != tls::TLSOPT_TO_LE)
1068               unsupported_reloc_global(object, r_type, gsym);
1069             break;
1070
1071           default:
1072             gold_unreachable();
1073           }
1074       }
1075       break;
1076
1077     case elfcpp::R_386_32PLT:
1078     case elfcpp::R_386_TLS_GD_32:
1079     case elfcpp::R_386_TLS_GD_PUSH:
1080     case elfcpp::R_386_TLS_GD_CALL:
1081     case elfcpp::R_386_TLS_GD_POP:
1082     case elfcpp::R_386_TLS_LDM_32:
1083     case elfcpp::R_386_TLS_LDM_PUSH:
1084     case elfcpp::R_386_TLS_LDM_CALL:
1085     case elfcpp::R_386_TLS_LDM_POP:
1086     case elfcpp::R_386_USED_BY_INTEL_200:
1087     default:
1088       unsupported_reloc_global(object, r_type, gsym);
1089       break;
1090     }
1091 }
1092
1093 // Scan relocations for a section.
1094
1095 void
1096 Target_i386::scan_relocs(const General_options& options,
1097                          Symbol_table* symtab,
1098                          Layout* layout,
1099                          Sized_relobj<32, false>* object,
1100                          unsigned int data_shndx,
1101                          unsigned int sh_type,
1102                          const unsigned char* prelocs,
1103                          size_t reloc_count,
1104                          size_t local_symbol_count,
1105                          const unsigned char* plocal_symbols,
1106                          Symbol** global_symbols)
1107 {
1108   if (sh_type == elfcpp::SHT_RELA)
1109     {
1110       gold_error(_("%s: unsupported RELA reloc section"),
1111                  object->name().c_str());
1112       return;
1113     }
1114
1115   gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
1116                     Target_i386::Scan>(
1117     options,
1118     symtab,
1119     layout,
1120     this,
1121     object,
1122     data_shndx,
1123     prelocs,
1124     reloc_count,
1125     local_symbol_count,
1126     plocal_symbols,
1127     global_symbols);
1128 }
1129
1130 // Finalize the sections.
1131
1132 void
1133 Target_i386::do_finalize_sections(Layout* layout)
1134 {
1135   // Fill in some more dynamic tags.
1136   Output_data_dynamic* const odyn = layout->dynamic_data();
1137   if (odyn != NULL)
1138     {
1139       if (this->got_plt_ != NULL)
1140         odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1141
1142       if (this->plt_ != NULL)
1143         {
1144           const Output_data* od = this->plt_->rel_plt();
1145           odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1146           odyn->add_section_address(elfcpp::DT_JMPREL, od);
1147           odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL);
1148         }
1149
1150       if (this->rel_dyn_ != NULL)
1151         {
1152           const Output_data* od = this->rel_dyn_;
1153           odyn->add_section_address(elfcpp::DT_REL, od);
1154           odyn->add_section_size(elfcpp::DT_RELSZ, od);
1155           odyn->add_constant(elfcpp::DT_RELENT,
1156                              elfcpp::Elf_sizes<32>::rel_size);
1157         }
1158
1159       if (!parameters->output_is_shared())
1160         {
1161           // The value of the DT_DEBUG tag is filled in by the dynamic
1162           // linker at run time, and used by the debugger.
1163           odyn->add_constant(elfcpp::DT_DEBUG, 0);
1164         }
1165     }
1166
1167   // Emit any relocs we saved in an attempt to avoid generating COPY
1168   // relocs.
1169   if (this->copy_relocs_ == NULL)
1170     return;
1171   if (this->copy_relocs_->any_to_emit())
1172     {
1173       Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1174       this->copy_relocs_->emit(rel_dyn);
1175     }
1176   delete this->copy_relocs_;
1177   this->copy_relocs_ = NULL;
1178 }
1179
1180 // Perform a relocation.
1181
1182 inline bool
1183 Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
1184                                 Target_i386* target,
1185                                 size_t relnum,
1186                                 const elfcpp::Rel<32, false>& rel,
1187                                 unsigned int r_type,
1188                                 const Sized_symbol<32>* gsym,
1189                                 const Symbol_value<32>* psymval,
1190                                 unsigned char* view,
1191                                 elfcpp::Elf_types<32>::Elf_Addr address,
1192                                 off_t view_size)
1193 {
1194   if (this->skip_call_tls_get_addr_)
1195     {
1196       if (r_type != elfcpp::R_386_PLT32
1197           || gsym == NULL
1198           || strcmp(gsym->name(), "___tls_get_addr") != 0)
1199         gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1200                                _("missing expected TLS relocation"));
1201       else
1202         {
1203           this->skip_call_tls_get_addr_ = false;
1204           return false;
1205         }
1206     }
1207
1208   // Pick the value to use for symbols defined in shared objects.
1209   Symbol_value<32> symval;
1210   if (gsym != NULL
1211       && (gsym->is_from_dynobj()
1212           || (parameters->output_is_shared()
1213               && gsym->is_preemptible()))
1214       && gsym->has_plt_offset())
1215     {
1216       symval.set_output_value(target->plt_section()->address()
1217                               + gsym->plt_offset());
1218       psymval = &symval;
1219     }
1220
1221   const Sized_relobj<32, false>* object = relinfo->object;
1222
1223   // Get the GOT offset if needed.
1224   bool have_got_offset = false;
1225   unsigned int got_offset = 0;
1226   switch (r_type)
1227     {
1228     case elfcpp::R_386_GOT32:
1229       if (gsym != NULL)
1230         {
1231           gold_assert(gsym->has_got_offset());
1232           got_offset = gsym->got_offset();
1233         }
1234       else
1235         {
1236           unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1237           got_offset = object->local_got_offset(r_sym);
1238         }
1239       have_got_offset = true;
1240       break;
1241
1242     default:
1243       break;
1244     }
1245
1246   switch (r_type)
1247     {
1248     case elfcpp::R_386_NONE:
1249     case elfcpp::R_386_GNU_VTINHERIT:
1250     case elfcpp::R_386_GNU_VTENTRY:
1251       break;
1252
1253     case elfcpp::R_386_32:
1254       Relocate_functions<32, false>::rel32(view, object, psymval);
1255       break;
1256
1257     case elfcpp::R_386_PC32:
1258       Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1259       break;
1260
1261     case elfcpp::R_386_16:
1262       Relocate_functions<32, false>::rel16(view, object, psymval);
1263       break;
1264
1265     case elfcpp::R_386_PC16:
1266       Relocate_functions<32, false>::pcrel16(view, object, psymval, address);
1267       break;
1268
1269     case elfcpp::R_386_8:
1270       Relocate_functions<32, false>::rel8(view, object, psymval);
1271       break;
1272
1273     case elfcpp::R_386_PC8:
1274       Relocate_functions<32, false>::pcrel8(view, object, psymval, address);
1275       break;
1276
1277     case elfcpp::R_386_PLT32:
1278       gold_assert(gsym == NULL
1279                   || gsym->has_plt_offset()
1280                   || gsym->final_value_is_known());
1281       Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1282       break;
1283
1284     case elfcpp::R_386_GOT32:
1285       gold_assert(have_got_offset);
1286       Relocate_functions<32, false>::rel32(view, got_offset);
1287       break;
1288
1289     case elfcpp::R_386_GOTOFF:
1290       {
1291         elfcpp::Elf_types<32>::Elf_Addr value;
1292         value = (psymval->value(object, 0)
1293                  - target->got_section(NULL, NULL)->address());
1294         Relocate_functions<32, false>::rel32(view, value);
1295       }
1296       break;
1297
1298     case elfcpp::R_386_GOTPC:
1299       {
1300         elfcpp::Elf_types<32>::Elf_Addr value;
1301         value = target->got_section(NULL, NULL)->address();
1302         Relocate_functions<32, false>::pcrel32(view, value, address);
1303       }
1304       break;
1305
1306     case elfcpp::R_386_COPY:
1307     case elfcpp::R_386_GLOB_DAT:
1308     case elfcpp::R_386_JUMP_SLOT:
1309     case elfcpp::R_386_RELATIVE:
1310       // These are outstanding tls relocs, which are unexpected when
1311       // linking.
1312     case elfcpp::R_386_TLS_TPOFF:
1313     case elfcpp::R_386_TLS_DTPMOD32:
1314     case elfcpp::R_386_TLS_DTPOFF32:
1315     case elfcpp::R_386_TLS_TPOFF32:
1316     case elfcpp::R_386_TLS_DESC:
1317       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1318                              _("unexpected reloc %u in object file"),
1319                              r_type);
1320       break;
1321
1322       // These are initial tls relocs, which are expected when
1323       // linking.
1324     case elfcpp::R_386_TLS_IE:
1325     case elfcpp::R_386_TLS_GOTIE:
1326     case elfcpp::R_386_TLS_LE:
1327     case elfcpp::R_386_TLS_GD:
1328     case elfcpp::R_386_TLS_LDM:
1329     case elfcpp::R_386_TLS_LDO_32:
1330     case elfcpp::R_386_TLS_IE_32:
1331     case elfcpp::R_386_TLS_LE_32:
1332     case elfcpp::R_386_TLS_GOTDESC:
1333     case elfcpp::R_386_TLS_DESC_CALL:
1334       this->relocate_tls(relinfo, relnum, rel, r_type, gsym, psymval, view,
1335                          address, view_size);
1336       break;
1337
1338     case elfcpp::R_386_32PLT:
1339     case elfcpp::R_386_TLS_GD_32:
1340     case elfcpp::R_386_TLS_GD_PUSH:
1341     case elfcpp::R_386_TLS_GD_CALL:
1342     case elfcpp::R_386_TLS_GD_POP:
1343     case elfcpp::R_386_TLS_LDM_32:
1344     case elfcpp::R_386_TLS_LDM_PUSH:
1345     case elfcpp::R_386_TLS_LDM_CALL:
1346     case elfcpp::R_386_TLS_LDM_POP:
1347     case elfcpp::R_386_USED_BY_INTEL_200:
1348     default:
1349       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1350                              _("unsupported reloc %u"),
1351                              r_type);
1352       break;
1353     }
1354
1355   return true;
1356 }
1357
1358 // Perform a TLS relocation.
1359
1360 inline void
1361 Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
1362                                     size_t relnum,
1363                                     const elfcpp::Rel<32, false>& rel,
1364                                     unsigned int r_type,
1365                                     const Sized_symbol<32>* gsym,
1366                                     const Symbol_value<32>* psymval,
1367                                     unsigned char* view,
1368                                     elfcpp::Elf_types<32>::Elf_Addr,
1369                                     off_t view_size)
1370 {
1371   Output_segment* tls_segment = relinfo->layout->tls_segment();
1372   if (tls_segment == NULL)
1373     {
1374       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1375                              _("TLS reloc but no TLS segment"));
1376       return;
1377     }
1378
1379   elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(relinfo->object, 0);
1380
1381   const bool is_final = (gsym == NULL
1382                          ? !parameters->output_is_position_independent()
1383                          : gsym->final_value_is_known());
1384   const tls::Tls_optimization optimized_type
1385       = Target_i386::optimize_tls_reloc(is_final, r_type);
1386   switch (r_type)
1387     {
1388     case elfcpp::R_386_TLS_LE_32:
1389       value = tls_segment->vaddr() + tls_segment->memsz() - value;
1390       Relocate_functions<32, false>::rel32(view, value);
1391       break;
1392
1393     case elfcpp::R_386_TLS_LE:
1394       value = value - (tls_segment->vaddr() + tls_segment->memsz());
1395       Relocate_functions<32, false>::rel32(view, value);
1396       break;
1397
1398     case elfcpp::R_386_TLS_IE:
1399     case elfcpp::R_386_TLS_GOTIE:
1400     case elfcpp::R_386_TLS_IE_32:
1401       if (optimized_type == tls::TLSOPT_TO_LE)
1402         {
1403           Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1404                                               rel, r_type, value, view,
1405                                               view_size);
1406           break;
1407         }
1408       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1409                              _("unsupported reloc %u"),
1410                              r_type);
1411       break;
1412
1413     case elfcpp::R_386_TLS_GD:
1414       if (optimized_type == tls::TLSOPT_TO_LE)
1415         {
1416           this->tls_gd_to_le(relinfo, relnum, tls_segment,
1417                              rel, r_type, value, view,
1418                              view_size);
1419           break;
1420         }
1421       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1422                              _("unsupported reloc %u"),
1423                              r_type);
1424       break;
1425
1426     case elfcpp::R_386_TLS_LDM:
1427       if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
1428         {
1429           gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1430                                  _("both SUN and GNU model "
1431                                    "TLS relocations"));
1432           break;
1433         }
1434       this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
1435       if (optimized_type == tls::TLSOPT_TO_LE)
1436         {
1437           this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
1438                              value, view, view_size);
1439           break;
1440         }
1441       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1442                              _("unsupported reloc %u"),
1443                              r_type);
1444       break;
1445
1446     case elfcpp::R_386_TLS_LDO_32:
1447       // This reloc can appear in debugging sections, in which case we
1448       // won't see the TLS_LDM reloc.  The local_dynamic_type field
1449       // tells us this.
1450       if (optimized_type != tls::TLSOPT_TO_LE
1451           || this->local_dynamic_type_ == LOCAL_DYNAMIC_NONE)
1452         value = value - tls_segment->vaddr();
1453       else if (this->local_dynamic_type_ == LOCAL_DYNAMIC_GNU)
1454         value = value - (tls_segment->vaddr() + tls_segment->memsz());
1455       else
1456         value = tls_segment->vaddr() + tls_segment->memsz() - value;
1457       Relocate_functions<32, false>::rel32(view, value);
1458       break;
1459
1460     case elfcpp::R_386_TLS_GOTDESC:
1461     case elfcpp::R_386_TLS_DESC_CALL:
1462       gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1463                              _("unsupported reloc %u"),
1464                              r_type);
1465       break;
1466     }
1467 }
1468
1469 // Do a relocation in which we convert a TLS Initial-Exec to a
1470 // Local-Exec.
1471
1472 inline void
1473 Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
1474                                     size_t relnum,
1475                                     Output_segment* tls_segment,
1476                                     const elfcpp::Rel<32, false>& rel,
1477                                     unsigned int r_type,
1478                                     elfcpp::Elf_types<32>::Elf_Addr value,
1479                                     unsigned char* view,
1480                                     off_t view_size)
1481 {
1482   // We have to actually change the instructions, which means that we
1483   // need to examine the opcodes to figure out which instruction we
1484   // are looking at.
1485   if (r_type == elfcpp::R_386_TLS_IE)
1486     {
1487       // movl %gs:XX,%eax  ==>  movl $YY,%eax
1488       // movl %gs:XX,%reg  ==>  movl $YY,%reg
1489       // addl %gs:XX,%reg  ==>  addl $YY,%reg
1490       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
1491       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
1492
1493       unsigned char op1 = view[-1];
1494       if (op1 == 0xa1)
1495         {
1496           // movl XX,%eax  ==>  movl $YY,%eax
1497           view[-1] = 0xb8;
1498         }
1499       else
1500         {
1501           tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1502
1503           unsigned char op2 = view[-2];
1504           if (op2 == 0x8b)
1505             {
1506               // movl XX,%reg  ==>  movl $YY,%reg
1507               tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1508                              (op1 & 0xc7) == 0x05);
1509               view[-2] = 0xc7;
1510               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1511             }
1512           else if (op2 == 0x03)
1513             {
1514               // addl XX,%reg  ==>  addl $YY,%reg
1515               tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1516                              (op1 & 0xc7) == 0x05);
1517               view[-2] = 0x81;
1518               view[-1] = 0xc0 | ((op1 >> 3) & 7);
1519             }
1520           else
1521             tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
1522         }
1523     }
1524   else
1525     {
1526       // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1527       // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1528       // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1529       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1530       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
1531
1532       unsigned char op1 = view[-1];
1533       unsigned char op2 = view[-2];
1534       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1535                      (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
1536       if (op2 == 0x8b)
1537         {
1538           // movl %gs:XX(%reg1),%reg2  ==>  movl $YY,%reg2
1539           view[-2] = 0xc7;
1540           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1541         }
1542       else if (op2 == 0x2b)
1543         {
1544           // subl %gs:XX(%reg1),%reg2  ==>  subl $YY,%reg2
1545           view[-2] = 0x81;
1546           view[-1] = 0xe8 | ((op1 >> 3) & 7);
1547         }
1548       else if (op2 == 0x03)
1549         {
1550           // addl %gs:XX(%reg1),%reg2  ==>  addl $YY,$reg2
1551           view[-2] = 0x81;
1552           view[-1] = 0xc0 | ((op1 >> 3) & 7);
1553         }
1554       else
1555         tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
1556     }
1557
1558   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1559   if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
1560     value = - value;
1561
1562   Relocate_functions<32, false>::rel32(view, value);
1563 }
1564
1565 // Do a relocation in which we convert a TLS General-Dynamic to a
1566 // Local-Exec.
1567
1568 inline void
1569 Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
1570                                     size_t relnum,
1571                                     Output_segment* tls_segment,
1572                                     const elfcpp::Rel<32, false>& rel,
1573                                     unsigned int,
1574                                     elfcpp::Elf_types<32>::Elf_Addr value,
1575                                     unsigned char* view,
1576                                     off_t view_size)
1577 {
1578   // leal foo(,%reg,1),%eax; call ___tls_get_addr
1579   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1580   // leal foo(%reg),%eax; call ___tls_get_addr
1581   //  ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1582
1583   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1584   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1585
1586   unsigned char op1 = view[-1];
1587   unsigned char op2 = view[-2];
1588
1589   tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1590                  op2 == 0x8d || op2 == 0x04);
1591   tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1592
1593   int roff = 5;
1594
1595   if (op2 == 0x04)
1596     {
1597       tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
1598       tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
1599       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1600                      ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
1601       memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1602     }
1603   else
1604     {
1605       tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1606                      (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1607       if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
1608           && view[9] == 0x90)
1609         {
1610           // There is a trailing nop.  Use the size byte subl.
1611           memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1612           roff = 6;
1613         }
1614       else
1615         {
1616           // Use the five byte subl.
1617           memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1618         }
1619     }
1620
1621   value = tls_segment->vaddr() + tls_segment->memsz() - value;
1622   Relocate_functions<32, false>::rel32(view + roff, value);
1623
1624   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1625   // We can skip it.
1626   this->skip_call_tls_get_addr_ = true;
1627 }
1628
1629 // Do a relocation in which we convert a TLS Local-Dynamic to a
1630 // Local-Exec.
1631
1632 inline void
1633 Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
1634                                     size_t relnum,
1635                                     Output_segment*,
1636                                     const elfcpp::Rel<32, false>& rel,
1637                                     unsigned int,
1638                                     elfcpp::Elf_types<32>::Elf_Addr,
1639                                     unsigned char* view,
1640                                     off_t view_size)
1641 {
1642   // leal foo(%reg), %eax; call ___tls_get_addr
1643   // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
1644
1645   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1646   tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1647
1648   // FIXME: Does this test really always pass?
1649   tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1650                  view[-2] == 0x8d && view[-1] == 0x83);
1651
1652   tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1653
1654   memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
1655
1656   // The next reloc should be a PLT32 reloc against __tls_get_addr.
1657   // We can skip it.
1658   this->skip_call_tls_get_addr_ = true;
1659 }
1660
1661 // Relocate section data.
1662
1663 void
1664 Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
1665                               unsigned int sh_type,
1666                               const unsigned char* prelocs,
1667                               size_t reloc_count,
1668                               unsigned char* view,
1669                               elfcpp::Elf_types<32>::Elf_Addr address,
1670                               off_t view_size)
1671 {
1672   gold_assert(sh_type == elfcpp::SHT_REL);
1673
1674   gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
1675                          Target_i386::Relocate>(
1676     relinfo,
1677     this,
1678     prelocs,
1679     reloc_count,
1680     view,
1681     address,
1682     view_size);
1683 }
1684
1685 // Return the value to use for a dynamic which requires special
1686 // treatment.  This is how we support equality comparisons of function
1687 // pointers across shared library boundaries, as described in the
1688 // processor specific ABI supplement.
1689
1690 uint64_t
1691 Target_i386::do_dynsym_value(const Symbol* gsym) const
1692 {
1693   gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
1694   return this->plt_section()->address() + gsym->plt_offset();
1695 }
1696
1697 // Return a string used to fill a code section with nops to take up
1698 // the specified length.
1699
1700 std::string
1701 Target_i386::do_code_fill(off_t length)
1702 {
1703   if (length >= 16)
1704     {
1705       // Build a jmp instruction to skip over the bytes.
1706       unsigned char jmp[5];
1707       jmp[0] = 0xe9;
1708       elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
1709       return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
1710               + std::string(length - 5, '\0'));
1711     }
1712
1713   // Nop sequences of various lengths.
1714   const char nop1[1] = { 0x90 };                   // nop
1715   const char nop2[2] = { 0x66, 0x90 };             // xchg %ax %ax
1716   const char nop3[3] = { 0x8d, 0x76, 0x00 };       // leal 0(%esi),%esi
1717   const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00};  // leal 0(%esi,1),%esi
1718   const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26,   // nop
1719                          0x00 };                   // leal 0(%esi,1),%esi
1720   const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00,   // leal 0L(%esi),%esi
1721                          0x00, 0x00 };
1722   const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00,   // leal 0L(%esi,1),%esi
1723                          0x00, 0x00, 0x00 };
1724   const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26,   // nop
1725                          0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
1726   const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc,   // movl %esi,%esi
1727                          0x27, 0x00, 0x00, 0x00,   // leal 0L(%edi,1),%edi
1728                          0x00 };
1729   const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
1730                            0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
1731                            0x00, 0x00 };
1732   const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
1733                            0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
1734                            0x00, 0x00, 0x00 };
1735   const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1736                            0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
1737                            0x00, 0x00, 0x00, 0x00 };
1738   const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
1739                            0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
1740                            0x27, 0x00, 0x00, 0x00,
1741                            0x00 };
1742   const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
1743                            0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
1744                            0xbc, 0x27, 0x00, 0x00,
1745                            0x00, 0x00 };
1746   const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
1747                            0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
1748                            0x90, 0x90, 0x90, 0x90,
1749                            0x90, 0x90, 0x90 };
1750
1751   const char* nops[16] = {
1752     NULL,
1753     nop1, nop2, nop3, nop4, nop5, nop6, nop7,
1754     nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
1755   };
1756
1757   return std::string(nops[length], length);
1758 }
1759
1760 // The selector for i386 object files.
1761
1762 class Target_selector_i386 : public Target_selector
1763 {
1764 public:
1765   Target_selector_i386()
1766     : Target_selector(elfcpp::EM_386, 32, false)
1767   { }
1768
1769   Target*
1770   recognize(int machine, int osabi, int abiversion);
1771
1772  private:
1773   Target_i386* target_;
1774 };
1775
1776 // Recognize an i386 object file when we already know that the machine
1777 // number is EM_386.
1778
1779 Target*
1780 Target_selector_i386::recognize(int, int, int)
1781 {
1782   if (this->target_ == NULL)
1783     this->target_ = new Target_i386();
1784   return this->target_;
1785 }
1786
1787 Target_selector_i386 target_selector_i386;
1788
1789 } // End anonymous namespace.