gold/target-reloc.h

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