gold/i386.cc

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