gold/target-reloc.h

   1 // target-reloc.h -- target specific relocation support  -*- C++ -*-
   2
   3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012
   4 // Free Software Foundation, Inc.
   5 // Written by Ian Lance Taylor <iant@google.com>.
   6
   7 // This file is part of gold.
   8
   9 // This program is free software; you can redistribute it and/or modify
  10 // it under the terms of the GNU General Public License as published by
  11 // the Free Software Foundation; either version 3 of the License, or
  12 // (at your option) any later version.
  13
  14 // This program is distributed in the hope that it will be useful,
  15 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 // GNU General Public License for more details.
  18
  19 // You should have received a copy of the GNU General Public License
  20 // along with this program; if not, write to the Free Software
  21 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  22 // MA 02110-1301, USA.
  23
  24 #ifndef GOLD_TARGET_RELOC_H
  25 #define GOLD_TARGET_RELOC_H
  26
  27 #include "elfcpp.h"
  28 #include "symtab.h"
  29 #include "object.h"
  30 #include "reloc.h"
  31 #include "reloc-types.h"
  32
  33 namespace gold
  34 {
  35
  36 // This function implements the generic part of reloc scanning.  The
  37 // template parameter Scan must be a class type which provides two
  38 // functions: local() and global().  Those functions implement the
  39 // machine specific part of scanning.  We do it this way to
  40 // avoid making a function call for each relocation, and to avoid
  41 // repeating the generic code for each target.
  42
  43 template<int size, bool big_endian, typename Target_type, int sh_type,
  44          typename Scan>
  45 inline void
  46 scan_relocs(
  47     Symbol_table* symtab,
  48     Layout* layout,
  49     Target_type* target,
  50     Sized_relobj_file<size, big_endian>* object,
  51     unsigned int data_shndx,
  52     const unsigned char* prelocs,
  53     size_t reloc_count,
  54     Output_section* output_section,
  55     bool needs_special_offset_handling,
  56     size_t local_count,
  57     const unsigned char* plocal_syms)
  58 {
  59   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
  60   const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
  61   const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
  62   Scan scan;
  63
  64   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
  65     {
  66       Reltype reloc(prelocs);
  67
  68       if (needs_special_offset_handling
  69           && !output_section->is_input_address_mapped(object, data_shndx,
  70                                                       reloc.get_r_offset()))
  71         continue;
  72
  73       typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info();
  74       unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
  75       unsigned int r_type = elfcpp::elf_r_type<size>(r_info);
  76
  77       if (r_sym < local_count)
  78         {
  79           gold_assert(plocal_syms != NULL);
  80           typename elfcpp::Sym<size, big_endian> lsym(plocal_syms
  81                                                       + r_sym * sym_size);
  82           unsigned int shndx = lsym.get_st_shndx();
  83           bool is_ordinary;
  84           shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
  85           // If RELOC is a relocation against a local symbol in a
  86           // section we are discarding then we can ignore it.  It will
  87           // eventually become a reloc against the value zero.
  88           //
  89           // FIXME: We should issue a warning if this is an
  90           // allocated section; is this the best place to do it?
  91           //
  92           // FIXME: The old GNU linker would in some cases look
  93           // for the linkonce section which caused this section to
  94           // be discarded, and, if the other section was the same
  95           // size, change the reloc to refer to the other section.
  96           // That seems risky and weird to me, and I don't know of
  97           // any case where it is actually required.
  98           bool is_discarded = (is_ordinary
  99                                && shndx != elfcpp::SHN_UNDEF
 100                                && !object->is_section_included(shndx)
 101                                && !symtab->is_section_folded(object, shndx));
 102           scan.local(symtab, layout, target, object, data_shndx,
 103                      output_section, reloc, r_type, lsym, is_discarded);
 104         }
 105       else
 106         {
 107           Symbol* gsym = object->global_symbol(r_sym);
 108           gold_assert(gsym != NULL);
 109           if (gsym->is_forwarder())
 110             gsym = symtab->resolve_forwards(gsym);
 111
 112           scan.global(symtab, layout, target, object, data_shndx,
 113                       output_section, reloc, r_type, gsym);
 114         }
 115     }
 116 }
 117
 118 // Behavior for relocations to discarded comdat sections.
 119
 120 enum Comdat_behavior
 121 {
 122   CB_UNDETERMINED,   // Not yet determined -- need to look at section name.
 123   CB_PRETEND,        // Attempt to map to the corresponding kept section.
 124   CB_IGNORE,         // Ignore the relocation.
 125   CB_WARNING         // Print a warning.
 126 };
 127
 128 class Default_comdat_behavior
 129 {
 130  public:
 131   // Decide what the linker should do for relocations that refer to
 132   // discarded comdat sections.  This decision is based on the name of
 133   // the section being relocated.
 134
 135   inline Comdat_behavior
 136   get(const char* name)
 137   {
 138     if (Layout::is_debug_info_section(name))
 139       return CB_PRETEND;
 140     if (strcmp(name, ".eh_frame") == 0
 141         || strcmp(name, ".gcc_except_table") == 0)
 142       return CB_IGNORE;
 143     return CB_WARNING;
 144   }
 145 };
 146
 147 // Give an error for a symbol with non-default visibility which is not
 148 // defined locally.
 149
 150 inline void
 151 visibility_error(const Symbol* sym)
 152 {
 153   const char* v;
 154   switch (sym->visibility())
 155     {
 156     case elfcpp::STV_INTERNAL:
 157       v = _("internal");
 158       break;
 159     case elfcpp::STV_HIDDEN:
 160       v = _("hidden");
 161       break;
 162     case elfcpp::STV_PROTECTED:
 163       v = _("protected");
 164       break;
 165     default:
 166       gold_unreachable();
 167     }
 168   gold_error(_("%s symbol '%s' is not defined locally"),
 169              v, sym->name());
 170 }
 171
 172 // Return true if we are should issue an error saying that SYM is an
 173 // undefined symbol.  This is called if there is a relocation against
 174 // SYM.
 175
 176 inline bool
 177 issue_undefined_symbol_error(const Symbol* sym)
 178 {
 179   // We only report global symbols.
 180   if (sym == NULL)
 181     return false;
 182
 183   // We only report undefined symbols.
 184   if (!sym->is_undefined() && !sym->is_placeholder())
 185     return false;
 186
 187   // We don't report weak symbols.
 188   if (sym->binding() == elfcpp::STB_WEAK)
 189     return false;
 190
 191   // We don't report symbols defined in discarded sections.
 192   if (sym->is_defined_in_discarded_section())
 193     return false;
 194
 195   // If the target defines this symbol, don't report it here.
 196   if (parameters->target().is_defined_by_abi(sym))
 197     return false;
 198
 199   // See if we've been told to ignore whether this symbol is
 200   // undefined.
 201   const char* const u = parameters->options().unresolved_symbols();
 202   if (u != NULL)
 203     {
 204       if (strcmp(u, "ignore-all") == 0)
 205         return false;
 206       if (strcmp(u, "report-all") == 0)
 207         return true;
 208       if (strcmp(u, "ignore-in-object-files") == 0 && !sym->in_dyn())
 209         return false;
 210       if (strcmp(u, "ignore-in-shared-libs") == 0 && !sym->in_reg())
 211         return false;
 212     }
 213
 214   // When creating a shared library, only report unresolved symbols if
 215   // -z defs was used.
 216   if (parameters->options().shared() && !parameters->options().defs())
 217     return false;
 218
 219   // Otherwise issue a warning.
 220   return true;
 221 }
 222
 223 // This function implements the generic part of relocation processing.
 224 // The template parameter Relocate must be a class type which provides
 225 // a single function, relocate(), which implements the machine
 226 // specific part of a relocation.
 227
 228 // The template parameter Relocate_comdat_behavior is a class type
 229 // which provides a single function, get(), which determines what the
 230 // linker should do for relocations that refer to discarded comdat
 231 // sections.
 232
 233 // SIZE is the ELF size: 32 or 64.  BIG_ENDIAN is the endianness of
 234 // the data.  SH_TYPE is the section type: SHT_REL or SHT_RELA.
 235 // RELOCATE implements operator() to do a relocation.
 236
 237 // PRELOCS points to the relocation data.  RELOC_COUNT is the number
 238 // of relocs.  OUTPUT_SECTION is the output section.
 239 // NEEDS_SPECIAL_OFFSET_HANDLING is true if input offsets need to be
 240 // mapped to output offsets.
 241
 242 // VIEW is the section data, VIEW_ADDRESS is its memory address, and
 243 // VIEW_SIZE is the size.  These refer to the input section, unless
 244 // NEEDS_SPECIAL_OFFSET_HANDLING is true, in which case they refer to
 245 // the output section.
 246
 247 // RELOC_SYMBOL_CHANGES is used for -fsplit-stack support.  If it is
 248 // not NULL, it is a vector indexed by relocation index.  If that
 249 // entry is not NULL, it points to a global symbol which used as the
 250 // symbol for the relocation, ignoring the symbol index in the
 251 // relocation.
 252
 253 template<int size, bool big_endian, typename Target_type, int sh_type,
 254          typename Relocate,
 255          typename Relocate_comdat_behavior>
 256 inline void
 257 relocate_section(
 258     const Relocate_info<size, big_endian>* relinfo,
 259     Target_type* target,
 260     const unsigned char* prelocs,
 261     size_t reloc_count,
 262     Output_section* output_section,
 263     bool needs_special_offset_handling,
 264     unsigned char* view,
 265     typename elfcpp::Elf_types<size>::Elf_Addr view_address,
 266     section_size_type view_size,
 267     const Reloc_symbol_changes* reloc_symbol_changes)
 268 {
 269   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
 270   const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
 271   Relocate relocate;
 272   Relocate_comdat_behavior relocate_comdat_behavior;
 273
 274   Sized_relobj_file<size, big_endian>* object = relinfo->object;
 275   unsigned int local_count = object->local_symbol_count();
 276
 277   Comdat_behavior comdat_behavior = CB_UNDETERMINED;
 278
 279   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
 280     {
 281       Reltype reloc(prelocs);
 282
 283       section_offset_type offset =
 284         convert_to_section_size_type(reloc.get_r_offset());
 285
 286       if (needs_special_offset_handling)
 287         {
 288           offset = output_section->output_offset(relinfo->object,
 289                                                  relinfo->data_shndx,
 290                                                  offset);
 291           if (offset == -1)
 292             continue;
 293         }
 294
 295       typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info();
 296       unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
 297       unsigned int r_type = elfcpp::elf_r_type<size>(r_info);
 298
 299       const Sized_symbol<size>* sym;
 300
 301       Symbol_value<size> symval;
 302       const Symbol_value<size> *psymval;
 303       bool is_defined_in_discarded_section;
 304       unsigned int shndx;
 305       if (r_sym < local_count
 306           && (reloc_symbol_changes == NULL
 307               || (*reloc_symbol_changes)[i] == NULL))
 308         {
 309           sym = NULL;
 310           psymval = object->local_symbol(r_sym);
 311
 312           // If the local symbol belongs to a section we are discarding,
 313           // and that section is a debug section, try to find the
 314           // corresponding kept section and map this symbol to its
 315           // counterpart in the kept section.  The symbol must not
 316           // correspond to a section we are folding.
 317           bool is_ordinary;
 318           shndx = psymval->input_shndx(&is_ordinary);
 319           is_defined_in_discarded_section =
 320             (is_ordinary
 321              && shndx != elfcpp::SHN_UNDEF
 322              && !object->is_section_included(shndx)
 323              && !relinfo->symtab->is_section_folded(object, shndx));
 324         }
 325       else
 326         {
 327           const Symbol* gsym;
 328           if (reloc_symbol_changes != NULL
 329               && (*reloc_symbol_changes)[i] != NULL)
 330             gsym = (*reloc_symbol_changes)[i];
 331           else
 332             {
 333               gsym = object->global_symbol(r_sym);
 334               gold_assert(gsym != NULL);
 335               if (gsym->is_forwarder())
 336                 gsym = relinfo->symtab->resolve_forwards(gsym);
 337             }
 338
 339           sym = static_cast<const Sized_symbol<size>*>(gsym);
 340           if (sym->has_symtab_index() && sym->symtab_index() != -1U)
 341             symval.set_output_symtab_index(sym->symtab_index());
 342           else
 343             symval.set_no_output_symtab_entry();
 344           symval.set_output_value(sym->value());
 345           if (gsym->type() == elfcpp::STT_TLS)
 346             symval.set_is_tls_symbol();
 347           else if (gsym->type() == elfcpp::STT_GNU_IFUNC)
 348             symval.set_is_ifunc_symbol();
 349           psymval = &symval;
 350
 351           is_defined_in_discarded_section =
 352             (gsym->is_defined_in_discarded_section()
 353              && gsym->is_undefined());
 354           shndx = 0;
 355         }
 356
 357       Symbol_value<size> symval2;
 358       if (is_defined_in_discarded_section)
 359         {
 360           if (comdat_behavior == CB_UNDETERMINED)
 361             {
 362               std::string name = object->section_name(relinfo->data_shndx);
 363               comdat_behavior = relocate_comdat_behavior.get(name.c_str());
 364             }
 365           if (comdat_behavior == CB_PRETEND)
 366             {
 367               // FIXME: This case does not work for global symbols.
 368               // We have no place to store the original section index.
 369               // Fortunately this does not matter for comdat sections,
 370               // only for sections explicitly discarded by a linker
 371               // script.
 372               bool found;
 373               typename elfcpp::Elf_types<size>::Elf_Addr value =
 374                 object->map_to_kept_section(shndx, &found);
 375               if (found)
 376                 symval2.set_output_value(value + psymval->input_value());
 377               else
 378                 symval2.set_output_value(0);
 379             }
 380           else
 381             {
 382               if (comdat_behavior == CB_WARNING)
 383                 gold_warning_at_location(relinfo, i, offset,
 384                                          _("relocation refers to discarded "
 385                                            "section"));
 386               symval2.set_output_value(0);
 387             }
 388           symval2.set_no_output_symtab_entry();
 389           psymval = &symval2;
 390         }
 391
 392       if (!relocate.relocate(relinfo, target, output_section, i, reloc,
 393                              r_type, sym, psymval, view + offset,
 394                              view_address + offset, view_size))
 395         continue;
 396
 397       if (offset < 0 || static_cast<section_size_type>(offset) >= view_size)
 398         {
 399           gold_error_at_location(relinfo, i, offset,
 400                                  _("reloc has bad offset %zu"),
 401                                  static_cast<size_t>(offset));
 402           continue;
 403         }
 404
 405       if (issue_undefined_symbol_error(sym))
 406         gold_undefined_symbol_at_location(sym, relinfo, i, offset);
 407       else if (sym != NULL
 408                && sym->visibility() != elfcpp::STV_DEFAULT
 409                && (sym->is_undefined() || sym->is_from_dynobj()))
 410         visibility_error(sym);
 411
 412       if (sym != NULL && sym->has_warning())
 413         relinfo->symtab->issue_warning(sym, relinfo, i, offset);
 414     }
 415 }
 416
 417 // Apply an incremental relocation.
 418
 419 template<int size, bool big_endian, typename Target_type,
 420          typename Relocate>
 421 void
 422 apply_relocation(const Relocate_info<size, big_endian>* relinfo,
 423                  Target_type* target,
 424                  typename elfcpp::Elf_types<size>::Elf_Addr r_offset,
 425                  unsigned int r_type,
 426                  typename elfcpp::Elf_types<size>::Elf_Swxword r_addend,
 427                  const Symbol* gsym,
 428                  unsigned char* view,
 429                  typename elfcpp::Elf_types<size>::Elf_Addr address,
 430                  section_size_type view_size)
 431 {
 432   // Construct the ELF relocation in a temporary buffer.
 433   const int reloc_size = elfcpp::Elf_sizes<size>::rela_size;
 434   unsigned char relbuf[reloc_size];
 435   elfcpp::Rela<size, big_endian> rel(relbuf);
 436   elfcpp::Rela_write<size, big_endian> orel(relbuf);
 437   orel.put_r_offset(r_offset);
 438   orel.put_r_info(elfcpp::elf_r_info<size>(0, r_type));
 439   orel.put_r_addend(r_addend);
 440
 441   // Setup a Symbol_value for the global symbol.
 442   const Sized_symbol<size>* sym = static_cast<const Sized_symbol<size>*>(gsym);
 443   Symbol_value<size> symval;
 444   gold_assert(sym->has_symtab_index() && sym->symtab_index() != -1U);
 445   symval.set_output_symtab_index(sym->symtab_index());
 446   symval.set_output_value(sym->value());
 447   if (gsym->type() == elfcpp::STT_TLS)
 448     symval.set_is_tls_symbol();
 449   else if (gsym->type() == elfcpp::STT_GNU_IFUNC)
 450     symval.set_is_ifunc_symbol();
 451
 452   Relocate relocate;
 453   relocate.relocate(relinfo, target, NULL, -1U, rel, r_type, sym, &symval,
 454                     view + r_offset, address + r_offset, view_size);
 455 }
 456
 457 // This class may be used as a typical class for the
 458 // Scan_relocatable_reloc parameter to scan_relocatable_relocs.  The
 459 // template parameter Classify_reloc must be a class type which
 460 // provides a function get_size_for_reloc which returns the number of
 461 // bytes to which a reloc applies.  This class is intended to capture
 462 // the most typical target behaviour, while still permitting targets
 463 // to define their own independent class for Scan_relocatable_reloc.
 464
 465 template<int sh_type, typename Classify_reloc>
 466 class Default_scan_relocatable_relocs
 467 {
 468  public:
 469   // Return the strategy to use for a local symbol which is not a
 470   // section symbol, given the relocation type.
 471   inline Relocatable_relocs::Reloc_strategy
 472   local_non_section_strategy(unsigned int r_type, Relobj*, unsigned int r_sym)
 473   {
 474     // We assume that relocation type 0 is NONE.  Targets which are
 475     // different must override.
 476     if (r_type == 0 && r_sym == 0)
 477       return Relocatable_relocs::RELOC_DISCARD;
 478     return Relocatable_relocs::RELOC_COPY;
 479   }
 480
 481   // Return the strategy to use for a local symbol which is a section
 482   // symbol, given the relocation type.
 483   inline Relocatable_relocs::Reloc_strategy
 484   local_section_strategy(unsigned int r_type, Relobj* object)
 485   {
 486     if (sh_type == elfcpp::SHT_RELA)
 487       return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA;
 488     else
 489       {
 490         Classify_reloc classify;
 491         switch (classify.get_size_for_reloc(r_type, object))
 492           {
 493           case 0:
 494             return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0;
 495           case 1:
 496             return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1;
 497           case 2:
 498             return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2;
 499           case 4:
 500             return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4;
 501           case 8:
 502             return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8;
 503           default:
 504             gold_unreachable();
 505           }
 506       }
 507   }
 508
 509   // Return the strategy to use for a global symbol, given the
 510   // relocation type, the object, and the symbol index.
 511   inline Relocatable_relocs::Reloc_strategy
 512   global_strategy(unsigned int, Relobj*, unsigned int)
 513   { return Relocatable_relocs::RELOC_COPY; }
 514 };
 515
 516 // Scan relocs during a relocatable link.  This is a default
 517 // definition which should work for most targets.
 518 // Scan_relocatable_reloc must name a class type which provides three
 519 // functions which return a Relocatable_relocs::Reloc_strategy code:
 520 // global_strategy, local_non_section_strategy, and
 521 // local_section_strategy.  Most targets should be able to use
 522 // Default_scan_relocatable_relocs as this class.
 523
 524 template<int size, bool big_endian, int sh_type,
 525          typename Scan_relocatable_reloc>
 526 void
 527 scan_relocatable_relocs(
 528     Symbol_table*,
 529     Layout*,
 530     Sized_relobj_file<size, big_endian>* object,
 531     unsigned int data_shndx,
 532     const unsigned char* prelocs,
 533     size_t reloc_count,
 534     Output_section* output_section,
 535     bool needs_special_offset_handling,
 536     size_t local_symbol_count,
 537     const unsigned char* plocal_syms,
 538     Relocatable_relocs* rr)
 539 {
 540   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
 541   const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
 542   const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 543   Scan_relocatable_reloc scan;
 544
 545   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
 546     {
 547       Reltype reloc(prelocs);
 548
 549       Relocatable_relocs::Reloc_strategy strategy;
 550
 551       if (needs_special_offset_handling
 552           && !output_section->is_input_address_mapped(object, data_shndx,
 553                                                       reloc.get_r_offset()))
 554         strategy = Relocatable_relocs::RELOC_DISCARD;
 555       else
 556         {
 557           typename elfcpp::Elf_types<size>::Elf_WXword r_info =
 558             reloc.get_r_info();
 559           const unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
 560           const unsigned int r_type = elfcpp::elf_r_type<size>(r_info);
 561
 562           if (r_sym >= local_symbol_count)
 563             strategy = scan.global_strategy(r_type, object, r_sym);
 564           else
 565             {
 566               gold_assert(plocal_syms != NULL);
 567               typename elfcpp::Sym<size, big_endian> lsym(plocal_syms
 568                                                           + r_sym * sym_size);
 569               unsigned int shndx = lsym.get_st_shndx();
 570               bool is_ordinary;
 571               shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
 572               if (is_ordinary
 573                   && shndx != elfcpp::SHN_UNDEF
 574                   && !object->is_section_included(shndx))
 575                 {
 576                   // RELOC is a relocation against a local symbol
 577                   // defined in a section we are discarding.  Discard
 578                   // the reloc.  FIXME: Should we issue a warning?
 579                   strategy = Relocatable_relocs::RELOC_DISCARD;
 580                 }
 581               else if (lsym.get_st_type() != elfcpp::STT_SECTION)
 582                 strategy = scan.local_non_section_strategy(r_type, object,
 583                                                            r_sym);
 584               else
 585                 {
 586                   strategy = scan.local_section_strategy(r_type, object);
 587                   if (strategy != Relocatable_relocs::RELOC_DISCARD)
 588                     object->output_section(shndx)->set_needs_symtab_index();
 589                 }
 590
 591               if (strategy == Relocatable_relocs::RELOC_COPY)
 592                 object->set_must_have_output_symtab_entry(r_sym);
 593             }
 594         }
 595
 596       rr->set_next_reloc_strategy(strategy);
 597     }
 598 }
 599
 600 // Relocate relocs.  Called for a relocatable link, and for --emit-relocs.
 601 // This is a default definition which should work for most targets.
 602
 603 template<int size, bool big_endian, int sh_type>
 604 void
 605 relocate_relocs(
 606     const Relocate_info<size, big_endian>* relinfo,
 607     const unsigned char* prelocs,
 608     size_t reloc_count,
 609     Output_section* output_section,
 610     typename elfcpp::Elf_types<size>::Elf_Off offset_in_output_section,
 611     const Relocatable_relocs* rr,
 612     unsigned char* view,
 613     typename elfcpp::Elf_types<size>::Elf_Addr view_address,
 614     section_size_type view_size,
 615     unsigned char* reloc_view,
 616     section_size_type reloc_view_size)
 617 {
 618   typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
 619   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
 620   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc_write
 621     Reltype_write;
 622   const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
 623   const Address invalid_address = static_cast<Address>(0) - 1;
 624
 625   Sized_relobj_file<size, big_endian>* const object = relinfo->object;
 626   const unsigned int local_count = object->local_symbol_count();
 627
 628   unsigned char* pwrite = reloc_view;
 629
 630   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
 631     {
 632       Relocatable_relocs::Reloc_strategy strategy = rr->strategy(i);
 633       if (strategy == Relocatable_relocs::RELOC_DISCARD)
 634         continue;
 635
 636       if (strategy == Relocatable_relocs::RELOC_SPECIAL)
 637         {
 638           // Target wants to handle this relocation.
 639           Sized_target<size, big_endian>* target =
 640             parameters->sized_target<size, big_endian>();
 641           target->relocate_special_relocatable(relinfo, sh_type, prelocs,
 642                                                i, output_section,
 643                                                offset_in_output_section,
 644                                                view, view_address,
 645                                                view_size, pwrite);
 646           pwrite += reloc_size;
 647           continue;
 648         }
 649       Reltype reloc(prelocs);
 650       Reltype_write reloc_write(pwrite);
 651
 652       typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info();
 653       const unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
 654       const unsigned int r_type = elfcpp::elf_r_type<size>(r_info);
 655
 656       // Get the new symbol index.
 657
 658       unsigned int new_symndx;
 659       if (r_sym < local_count)
 660         {
 661           switch (strategy)
 662             {
 663             case Relocatable_relocs::RELOC_COPY:
 664               if (r_sym == 0)
 665                 new_symndx = 0;
 666               else
 667                 {
 668                   new_symndx = object->symtab_index(r_sym);
 669                   gold_assert(new_symndx != -1U);
 670                 }
 671               break;
 672
 673             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA:
 674             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0:
 675             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1:
 676             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2:
 677             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4:
 678             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8:
 679             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4_UNALIGNED:
 680               {
 681                 // We are adjusting a section symbol.  We need to find
 682                 // the symbol table index of the section symbol for
 683                 // the output section corresponding to input section
 684                 // in which this symbol is defined.
 685                 gold_assert(r_sym < local_count);
 686                 bool is_ordinary;
 687                 unsigned int shndx =
 688                   object->local_symbol_input_shndx(r_sym, &is_ordinary);
 689                 gold_assert(is_ordinary);
 690                 Output_section* os = object->output_section(shndx);
 691                 gold_assert(os != NULL);
 692                 gold_assert(os->needs_symtab_index());
 693                 new_symndx = os->symtab_index();
 694               }
 695               break;
 696
 697             default:
 698               gold_unreachable();
 699             }
 700         }
 701       else
 702         {
 703           const Symbol* gsym = object->global_symbol(r_sym);
 704           gold_assert(gsym != NULL);
 705           if (gsym->is_forwarder())
 706             gsym = relinfo->symtab->resolve_forwards(gsym);
 707
 708           gold_assert(gsym->has_symtab_index());
 709           new_symndx = gsym->symtab_index();
 710         }
 711
 712       // Get the new offset--the location in the output section where
 713       // this relocation should be applied.
 714
 715       Address offset = reloc.get_r_offset();
 716       Address new_offset;
 717       if (offset_in_output_section != invalid_address)
 718         new_offset = offset + offset_in_output_section;
 719       else
 720         {
 721           section_offset_type sot_offset =
 722               convert_types<section_offset_type, Address>(offset);
 723           section_offset_type new_sot_offset =
 724               output_section->output_offset(object, relinfo->data_shndx,
 725                                             sot_offset);
 726           gold_assert(new_sot_offset != -1);
 727           new_offset = new_sot_offset;
 728         }
 729
 730       // In an object file, r_offset is an offset within the section.
 731       // In an executable or dynamic object, generated by
 732       // --emit-relocs, r_offset is an absolute address.
 733       if (!parameters->options().relocatable())
 734         {
 735           new_offset += view_address;
 736           if (offset_in_output_section != invalid_address)
 737             new_offset -= offset_in_output_section;
 738         }
 739
 740       reloc_write.put_r_offset(new_offset);
 741       reloc_write.put_r_info(elfcpp::elf_r_info<size>(new_symndx, r_type));
 742
 743       // Handle the reloc addend based on the strategy.
 744
 745       if (strategy == Relocatable_relocs::RELOC_COPY)
 746         {
 747           if (sh_type == elfcpp::SHT_RELA)
 748             Reloc_types<sh_type, size, big_endian>::
 749               copy_reloc_addend(&reloc_write,
 750                                 &reloc);
 751         }
 752       else
 753         {
 754           // The relocation uses a section symbol in the input file.
 755           // We are adjusting it to use a section symbol in the output
 756           // file.  The input section symbol refers to some address in
 757           // the input section.  We need the relocation in the output
 758           // file to refer to that same address.  This adjustment to
 759           // the addend is the same calculation we use for a simple
 760           // absolute relocation for the input section symbol.
 761
 762           const Symbol_value<size>* psymval = object->local_symbol(r_sym);
 763
 764           unsigned char* padd = view + offset;
 765           switch (strategy)
 766             {
 767             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA:
 768               {
 769                 typename elfcpp::Elf_types<size>::Elf_Swxword addend;
 770                 addend = Reloc_types<sh_type, size, big_endian>::
 771                            get_reloc_addend(&reloc);
 772                 addend = psymval->value(object, addend);
 773                 Reloc_types<sh_type, size, big_endian>::
 774                   set_reloc_addend(&reloc_write, addend);
 775               }
 776               break;
 777
 778             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0:
 779               break;
 780
 781             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1:
 782               Relocate_functions<size, big_endian>::rel8(padd, object,
 783                                                          psymval);
 784               break;
 785
 786             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2:
 787               Relocate_functions<size, big_endian>::rel16(padd, object,
 788                                                           psymval);
 789               break;
 790
 791             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4:
 792               Relocate_functions<size, big_endian>::rel32(padd, object,
 793                                                           psymval);
 794               break;
 795
 796             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8:
 797               Relocate_functions<size, big_endian>::rel64(padd, object,
 798                                                           psymval);
 799               break;
 800
 801             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4_UNALIGNED:
 802               Relocate_functions<size, big_endian>::rel32_unaligned(padd,
 803                                                                     object,
 804                                                                     psymval);
 805               break;
 806
 807             default:
 808               gold_unreachable();
 809             }
 810         }
 811
 812       pwrite += reloc_size;
 813     }
 814
 815   gold_assert(static_cast<section_size_type>(pwrite - reloc_view)
 816               == reloc_view_size);
 817 }
 818
 819 } // End namespace gold.
 820
 821 #endif // !defined(GOLD_TARGET_RELOC_H)