gold/reloc.cc

   1 // reloc.cc -- relocate input files for gold.
   2
   3 #include "gold.h"
   4
   5 #include "workqueue.h"
   6 #include "object.h"
   7 #include "output.h"
   8 #include "reloc.h"
   9
  10 namespace gold
  11 {
  12
  13 // Read_relocs methods.
  14
  15 // These tasks just read the relocation information from the file.
  16 // After reading it, the start another task to process the
  17 // information.  These tasks requires access to the file.
  18
  19 Task::Is_runnable_type
  20 Read_relocs::is_runnable(Workqueue*)
  21 {
  22   return this->object_->is_locked() ? IS_LOCKED : IS_RUNNABLE;
  23 }
  24
  25 // Lock the file.
  26
  27 Task_locker*
  28 Read_relocs::locks(Workqueue*)
  29 {
  30   return new Task_locker_obj<Object>(*this->object_);
  31 }
  32
  33 // Read the relocations and then start a Scan_relocs_task.
  34
  35 void
  36 Read_relocs::run(Workqueue* workqueue)
  37 {
  38   Read_relocs_data *rd = new Read_relocs_data;
  39   this->object_->read_relocs(rd);
  40   workqueue->queue_front(new Scan_relocs(this->options_, this->symtab_,
  41                                          this->object_, rd, this->symtab_lock_,
  42                                          this->blocker_));
  43 }
  44
  45 // Scan_relocs methods.
  46
  47 // These tasks scan the relocations read by Read_relocs and mark up
  48 // the symbol table to indicate which relocations are required.  We
  49 // use a lock on the symbol table to keep them from interfering with
  50 // each other.
  51
  52 Task::Is_runnable_type
  53 Scan_relocs::is_runnable(Workqueue*)
  54 {
  55   return this->symtab_lock_->is_writable() ? IS_RUNNABLE : IS_LOCKED;
  56 }
  57
  58 // Return the locks we hold: one on the file, one on the symbol table
  59 // and one blocker.
  60
  61 class Scan_relocs::Scan_relocs_locker : public Task_locker
  62 {
  63  public:
  64   Scan_relocs_locker(Object* object, Task_token& symtab_lock, Task* task,
  65                      Task_token& blocker, Workqueue* workqueue)
  66     : objlock_(*object), symtab_locker_(symtab_lock, task),
  67       blocker_(blocker, workqueue)
  68   { }
  69
  70  private:
  71   Task_locker_obj<Object> objlock_;
  72   Task_locker_write symtab_locker_;
  73   Task_locker_block blocker_;
  74 };
  75
  76 Task_locker*
  77 Scan_relocs::locks(Workqueue* workqueue)
  78 {
  79   return new Scan_relocs_locker(this->object_, *this->symtab_lock_, this,
  80                                 *this->blocker_, workqueue);
  81 }
  82
  83 // Scan the relocs.
  84
  85 void
  86 Scan_relocs::run(Workqueue*)
  87 {
  88   this->object_->scan_relocs(this->options_, this->symtab_, this->rd_);
  89   delete this->rd_;
  90   this->rd_ = NULL;
  91 }
  92
  93 // Relocate_task methods.
  94
  95 // These tasks are always runnable.
  96
  97 Task::Is_runnable_type
  98 Relocate_task::is_runnable(Workqueue*)
  99 {
 100   return IS_RUNNABLE;
 101 }
 102
 103 // We want to lock the file while we run.  We want to unblock
 104 // FINAL_BLOCKER when we are done.
 105
 106 class Relocate_task::Relocate_locker : public Task_locker
 107 {
 108  public:
 109   Relocate_locker(Task_token& token, Workqueue* workqueue,
 110                   Object* object)
 111     : blocker_(token, workqueue), objlock_(*object)
 112   { }
 113
 114  private:
 115   Task_locker_block blocker_;
 116   Task_locker_obj<Object> objlock_;
 117 };
 118
 119 Task_locker*
 120 Relocate_task::locks(Workqueue* workqueue)
 121 {
 122   return new Relocate_locker(*this->final_blocker_, workqueue,
 123                              this->object_);
 124 }
 125
 126 // Run the task.
 127
 128 void
 129 Relocate_task::run(Workqueue*)
 130 {
 131   this->object_->relocate(this->options_, this->symtab_, this->layout_,
 132                           this->of_);
 133 }
 134
 135 // Read the relocs and local symbols from the object file and store
 136 // the information in RD.
 137
 138 template<int size, bool big_endian>
 139 void
 140 Sized_object<size, big_endian>::do_read_relocs(Read_relocs_data* rd)
 141 {
 142   rd->relocs.clear();
 143
 144   unsigned int shnum = this->shnum();
 145   if (shnum == 0)
 146     return;
 147
 148   rd->relocs.reserve(shnum / 2);
 149
 150   const unsigned char *pshdrs = this->get_view(this->shoff_,
 151                                                shnum * This::shdr_size);
 152   // Skip the first, dummy, section.
 153   const unsigned char *ps = pshdrs + This::shdr_size;
 154   for (unsigned int i = 1; i < shnum; ++i, ps += This::shdr_size)
 155     {
 156       typename This::Shdr shdr(ps);
 157
 158       unsigned int sh_type = shdr.get_sh_type();
 159       if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
 160         continue;
 161
 162       unsigned int shndx = shdr.get_sh_info();
 163       if (shndx >= shnum)
 164         {
 165           fprintf(stderr, _("%s: %s: relocation section %u has bad info %u\n"),
 166                   program_name, this->name().c_str(), i, shndx);
 167           gold_exit(false);
 168         }
 169
 170       if (!this->is_section_included(shndx))
 171         continue;
 172
 173       if (shdr.get_sh_link() != this->symtab_shnum_)
 174         {
 175           fprintf(stderr,
 176                   _("%s: %s: relocation section %u uses unexpected "
 177                     "symbol table %u\n"),
 178                   program_name, this->name().c_str(), i, shdr.get_sh_link());
 179           gold_exit(false);
 180         }
 181
 182       off_t sh_size = shdr.get_sh_size();
 183
 184       unsigned int reloc_size;
 185       if (sh_type == elfcpp::SHT_REL)
 186         reloc_size = elfcpp::Elf_sizes<size>::rel_size;
 187       else
 188         reloc_size = elfcpp::Elf_sizes<size>::rela_size;
 189       if (reloc_size != shdr.get_sh_entsize())
 190         {
 191           fprintf(stderr,
 192                   _("%s: %s: unexpected entsize for reloc section %u: "
 193                     "%lu != %u"),
 194                   program_name, this->name().c_str(), i,
 195                   static_cast<unsigned long>(shdr.get_sh_entsize()),
 196                   reloc_size);
 197           gold_exit(false);
 198         }
 199
 200       size_t reloc_count = sh_size / reloc_size;
 201       if (reloc_count * reloc_size != sh_size)
 202         {
 203           fprintf(stderr, _("%s: %s: reloc section %u size %lu uneven"),
 204                   program_name, this->name().c_str(), i,
 205                   static_cast<unsigned long>(sh_size));
 206           gold_exit(false);
 207         }
 208
 209       rd->relocs.push_back(Section_relocs());
 210       Section_relocs& sr(rd->relocs.back());
 211       sr.reloc_shndx = i;
 212       sr.data_shndx = shndx;
 213       sr.contents = this->get_lasting_view(shdr.get_sh_offset(), sh_size);
 214       sr.sh_type = sh_type;
 215       sr.reloc_count = reloc_count;
 216     }
 217
 218   // Read the local symbols.
 219   if (this->symtab_shnum_ == 0 || this->local_symbol_count_ == 0)
 220     rd->local_symbols = NULL;
 221   else
 222     {
 223       typename This::Shdr symtabshdr(pshdrs
 224                                      + this->symtab_shnum_ * This::shdr_size);
 225       assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
 226       const int sym_size = This::sym_size;
 227       const unsigned int loccount = this->local_symbol_count_;
 228       assert(loccount == symtabshdr.get_sh_info());
 229       off_t locsize = loccount * sym_size;
 230       rd->local_symbols = this->get_lasting_view(symtabshdr.get_sh_offset(),
 231                                                  locsize);
 232     }
 233 }
 234
 235 // Scan the relocs and adjust the symbol table.  This looks for
 236 // relocations which require GOT/PLT/COPY relocations.
 237
 238 template<int size, bool big_endian>
 239 void
 240 Sized_object<size, big_endian>::do_scan_relocs(const General_options& options,
 241                                                Symbol_table* symtab,
 242                                                Read_relocs_data* rd)
 243 {
 244   Sized_target<size, big_endian>* target = this->sized_target();
 245
 246   const unsigned char* local_symbols;
 247   if (rd->local_symbols == NULL)
 248     local_symbols = NULL;
 249   else
 250     local_symbols = rd->local_symbols->data();
 251
 252   for (Read_relocs_data::Relocs_list::iterator p = rd->relocs.begin();
 253        p != rd->relocs.end();
 254        ++p)
 255     {
 256       target->scan_relocs(options, symtab, this, p->sh_type,
 257                           p->contents->data(), p->reloc_count,
 258                           this->local_symbol_count_,
 259                           local_symbols,
 260                           this->symbols_);
 261       delete p->contents;
 262       p->contents = NULL;
 263     }
 264
 265   if (rd->local_symbols != NULL)
 266     {
 267       delete rd->local_symbols;
 268       rd->local_symbols = NULL;
 269     }
 270 }
 271
 272 // Relocate the input sections and write out the local symbols.
 273
 274 template<int size, bool big_endian>
 275 void
 276 Sized_object<size, big_endian>::do_relocate(const General_options& options,
 277                                             const Symbol_table* symtab,
 278                                             const Layout* layout,
 279                                             Output_file* of)
 280 {
 281   unsigned int shnum = this->shnum();
 282
 283   // Read the section headers.
 284   const unsigned char* pshdrs = this->get_view(this->shoff_,
 285                                                shnum * This::shdr_size);
 286
 287   Views views;
 288   views.resize(shnum);
 289
 290   // Make two passes over the sections.  The first one copies the
 291   // section data to the output file.  The second one applies
 292   // relocations.
 293
 294   this->write_sections(pshdrs, of, &views);
 295
 296   // Apply relocations.
 297
 298   this->relocate_sections(options, symtab, layout, pshdrs, &views);
 299
 300   // Write out the accumulated views.
 301   for (unsigned int i = 1; i < shnum; ++i)
 302     {
 303       if (views[i].view != NULL)
 304         of->write_output_view(views[i].offset, views[i].view_size,
 305                               views[i].view);
 306     }
 307
 308   // Write out the local symbols.
 309   this->write_local_symbols(of, layout->sympool());
 310 }
 311
 312 // Write section data to the output file.  PSHDRS points to the
 313 // section headers.  Record the views in *PVIEWS for use when
 314 // relocating.
 315
 316 template<int size, bool big_endian>
 317 void
 318 Sized_object<size, big_endian>::write_sections(const unsigned char* pshdrs,
 319                                                Output_file* of,
 320                                                Views* pviews)
 321 {
 322   unsigned int shnum = this->shnum();
 323   std::vector<Map_to_output>& map_sections(this->map_to_output());
 324
 325   const unsigned char* p = pshdrs + This::shdr_size;
 326   for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
 327     {
 328       View_size* pvs = &(*pviews)[i];
 329
 330       pvs->view = NULL;
 331
 332       const Output_section* os = map_sections[i].output_section;
 333       if (os == NULL)
 334         continue;
 335
 336       typename This::Shdr shdr(p);
 337
 338       if (shdr.get_sh_type() == elfcpp::SHT_NOBITS)
 339         continue;
 340
 341       assert(map_sections[i].offset >= 0
 342              && map_sections[i].offset < os->data_size());
 343       off_t start = os->offset() + map_sections[i].offset;
 344       off_t sh_size = shdr.get_sh_size();
 345
 346       unsigned char* view = of->get_output_view(start, sh_size);
 347       this->read(shdr.get_sh_offset(), sh_size, view);
 348
 349       pvs->view = view;
 350       pvs->address = os->address() + map_sections[i].offset;
 351       pvs->offset = start;
 352       pvs->view_size = sh_size;
 353     }
 354 }
 355
 356 // Relocate section data.  VIEWS points to the section data as views
 357 // in the output file.
 358
 359 template<int size, bool big_endian>
 360 void
 361 Sized_object<size, big_endian>::relocate_sections(
 362     const General_options& options,
 363     const Symbol_table* symtab,
 364     const Layout* layout,
 365     const unsigned char* pshdrs,
 366     Views* pviews)
 367 {
 368   unsigned int shnum = this->shnum();
 369   Sized_target<size, big_endian>* target = this->sized_target();
 370
 371   Relocate_info<size, big_endian> relinfo;
 372   relinfo.options = &options;
 373   relinfo.symtab = symtab;
 374   relinfo.layout = layout;
 375   relinfo.object = this;
 376   relinfo.local_symbol_count = this->local_symbol_count_;
 377   relinfo.values = this->values_;
 378   relinfo.symbols = this->symbols_;
 379
 380   const unsigned char* p = pshdrs + This::shdr_size;
 381   for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
 382     {
 383       typename This::Shdr shdr(p);
 384
 385       unsigned int sh_type = shdr.get_sh_type();
 386       if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
 387         continue;
 388
 389       unsigned int index = shdr.get_sh_info();
 390       if (index >= this->shnum())
 391         {
 392           fprintf(stderr, _("%s: %s: relocation section %u has bad info %u\n"),
 393                   program_name, this->name().c_str(), i, index);
 394           gold_exit(false);
 395         }
 396
 397       if (!this->is_section_included(index))
 398         {
 399           // This relocation section is against a section which we
 400           // discarded.
 401           continue;
 402         }
 403
 404       assert((*pviews)[index].view != NULL);
 405
 406       if (shdr.get_sh_link() != this->symtab_shnum_)
 407         {
 408           fprintf(stderr,
 409                   _("%s: %s: relocation section %u uses unexpected "
 410                     "symbol table %u\n"),
 411                   program_name, this->name().c_str(), i, shdr.get_sh_link());
 412           gold_exit(false);
 413         }
 414
 415       off_t sh_size = shdr.get_sh_size();
 416       const unsigned char* prelocs = this->get_view(shdr.get_sh_offset(),
 417                                                     sh_size);
 418
 419       unsigned int reloc_size;
 420       if (sh_type == elfcpp::SHT_REL)
 421         reloc_size = elfcpp::Elf_sizes<size>::rel_size;
 422       else
 423         reloc_size = elfcpp::Elf_sizes<size>::rela_size;
 424
 425       if (reloc_size != shdr.get_sh_entsize())
 426         {
 427           fprintf(stderr,
 428                   _("%s: %s: unexpected entsize for reloc section %u: "
 429                     "%lu != %u"),
 430                   program_name, this->name().c_str(), i,
 431                   static_cast<unsigned long>(shdr.get_sh_entsize()),
 432                   reloc_size);
 433           gold_exit(false);
 434         }
 435
 436       size_t reloc_count = sh_size / reloc_size;
 437       if (reloc_count * reloc_size != sh_size)
 438         {
 439           fprintf(stderr, _("%s: %s: reloc section %u size %lu uneven"),
 440                   program_name, this->name().c_str(), i,
 441                   static_cast<unsigned long>(sh_size));
 442           gold_exit(false);
 443         }
 444
 445       relinfo.reloc_shndx = i;
 446       relinfo.data_shndx = index;
 447       target->relocate_section(&relinfo,
 448                                sh_type,
 449                                prelocs,
 450                                reloc_count,
 451                                (*pviews)[index].view,
 452                                (*pviews)[index].address,
 453                                (*pviews)[index].view_size);
 454     }
 455 }
 456
 457 // Instantiate the templates we need.  We could use the configure
 458 // script to restrict this to only the ones for implemented targets.
 459
 460 template
 461 void
 462 Sized_object<32, false>::do_read_relocs(Read_relocs_data* rd);
 463
 464 template
 465 void
 466 Sized_object<32, true>::do_read_relocs(Read_relocs_data* rd);
 467
 468 template
 469 void
 470 Sized_object<64, false>::do_read_relocs(Read_relocs_data* rd);
 471
 472 template
 473 void
 474 Sized_object<64, true>::do_read_relocs(Read_relocs_data* rd);
 475
 476 template
 477 void
 478 Sized_object<32, false>::do_scan_relocs(const General_options& options,
 479                                         Symbol_table* symtab,
 480                                         Read_relocs_data* rd);
 481
 482 template
 483 void
 484 Sized_object<32, true>::do_scan_relocs(const General_options& options,
 485                                        Symbol_table* symtab,
 486                                        Read_relocs_data* rd);
 487
 488 template
 489 void
 490 Sized_object<64, false>::do_scan_relocs(const General_options& options,
 491                                         Symbol_table* symtab,
 492                                         Read_relocs_data* rd);
 493
 494 template
 495 void
 496 Sized_object<64, true>::do_scan_relocs(const General_options& options,
 497                                        Symbol_table* symtab,
 498                                        Read_relocs_data* rd);
 499
 500 template
 501 void
 502 Sized_object<32, false>::do_relocate(const General_options& options,
 503                                      const Symbol_table* symtab,
 504                                      const Layout* layout,
 505                                      Output_file* of);
 506
 507 template
 508 void
 509 Sized_object<32, true>::do_relocate(const General_options& options,
 510                                     const Symbol_table* symtab,
 511                                     const Layout* layout,
 512                                     Output_file* of);
 513
 514 template
 515 void
 516 Sized_object<64, false>::do_relocate(const General_options& options,
 517                                      const Symbol_table* symtab,
 518                                      const Layout* layout,
 519                                      Output_file* of);
 520
 521 template
 522 void
 523 Sized_object<64, true>::do_relocate(const General_options& options,
 524                                     const Symbol_table* symtab,
 525                                     const Layout* layout,
 526                                     Output_file* of);
 527
 528
 529 } // End namespace gold.