gold/target-reloc.h

   1 // target-reloc.h -- target specific relocation support  -*- C++ -*-
   2
   3 #ifndef GOLD_TARGET_RELOC_H
   4 #define GOLD_TARGET_RELOC_H
   5
   6 #include "elfcpp.h"
   7 #include "object.h"
   8 #include "symtab.h"
   9
  10 namespace gold
  11 {
  12
  13 // Pick the ELF relocation accessor class and the size based on
  14 // SH_TYPE, which is either SHT_REL or SHT_RELA.
  15
  16 template<int sh_type, int size, bool big_endian>
  17 struct Reloc_types;
  18
  19 template<int size, bool big_endian>
  20 struct Reloc_types<elfcpp::SHT_REL, size, big_endian>
  21 {
  22   typedef typename elfcpp::Rel<size, big_endian> Reloc;
  23   static const int reloc_size = elfcpp::Elf_sizes<size>::rel_size;
  24 };
  25
  26 template<int size, bool big_endian>
  27 struct Reloc_types<elfcpp::SHT_RELA, size, big_endian>
  28 {
  29   typedef typename elfcpp::Rela<size, big_endian> Reloc;
  30   static const int reloc_size = elfcpp::Elf_sizes<size>::rela_size;
  31 };
  32
  33 // This function implements the generic part of reloc scanning.  This
  34 // is an inline function which takes a class whose operator()
  35 // implements the machine specific part of scanning.  We do it this
  36 // way to avoidmaking a function call for each relocation, and to
  37 // avoid repeating the generic code for each target.
  38
  39 template<int size, bool big_endian, typename Target_type, int sh_type,
  40          typename Scan>
  41 inline void
  42 scan_relocs(
  43     const General_options& options,
  44     Symbol_table* symtab,
  45     Layout* layout,
  46     Target_type* target,
  47     Sized_object<size, big_endian>* object,
  48     const unsigned char* prelocs,
  49     size_t reloc_count,
  50     size_t local_count,
  51     const unsigned char* plocal_syms,
  52     Symbol** global_syms)
  53 {
  54   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
  55   const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
  56   const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
  57   Scan scan;
  58
  59   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
  60     {
  61       Reltype reloc(prelocs);
  62
  63       typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info();
  64       unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
  65       unsigned int r_type = elfcpp::elf_r_type<size>(r_info);
  66
  67       if (r_sym < local_count)
  68         {
  69           assert(plocal_syms != NULL);
  70           typename elfcpp::Sym<size, big_endian> lsym(plocal_syms
  71                                                       + r_sym * sym_size);
  72           const unsigned int shndx = lsym.get_st_shndx();
  73           if (shndx < elfcpp::SHN_LORESERVE
  74               && shndx != elfcpp::SHN_UNDEF
  75               && !object->is_section_included(lsym.get_st_shndx()))
  76             {
  77               // RELOC is a relocation against a local symbol in a
  78               // section we are discarding.  We can ignore this
  79               // relocation.  It will eventually become a reloc
  80               // against the value zero.
  81               //
  82               // FIXME: We should issue a warning if this is an
  83               // allocated section; is this the best place to do it?
  84               //
  85               // FIXME: The old GNU linker would in some cases look
  86               // for the linkonce section which caused this section to
  87               // be discarded, and, if the other section was the same
  88               // size, change the reloc to refer to the other section.
  89               // That seems risky and weird to me, and I don't know of
  90               // any case where it is actually required.
  91
  92               continue;
  93             }
  94
  95           scan.local(options, symtab, layout, target, object, reloc, r_type,
  96                      lsym);
  97         }
  98       else
  99         {
 100           Symbol* gsym = global_syms[r_sym - local_count];
 101           assert(gsym != NULL);
 102           if (gsym->is_forwarder())
 103             gsym = symtab->resolve_forwards(gsym);
 104
 105           scan.global(options, symtab, layout, target, object, reloc, r_type,
 106                       gsym);
 107         }
 108     }
 109 }
 110
 111 // This function implements the generic part of relocation processing.
 112 // This is an inline function which take a class whose operator()
 113 // implements the machine specific part of relocation.  We do it this
 114 // way to avoid making a function call for each relocation, and to
 115 // avoid repeating the generic relocation handling code for each
 116 // target.
 117
 118 // SIZE is the ELF size: 32 or 64.  BIG_ENDIAN is the endianness of
 119 // the data.  SH_TYPE is the section type: SHT_REL or SHT_RELA.
 120 // RELOCATE implements operator() to do a relocation.
 121
 122 // PRELOCS points to the relocation data.  RELOC_COUNT is the number
 123 // of relocs.  VIEW is the section data, VIEW_ADDRESS is its memory
 124 // address, and VIEW_SIZE is the size.
 125
 126 template<int size, bool big_endian, typename Target_type, int sh_type,
 127          typename Relocate>
 128 inline void
 129 relocate_section(
 130     const Relocate_info<size, big_endian>* relinfo,
 131     Target_type* target,
 132     const unsigned char* prelocs,
 133     size_t reloc_count,
 134     unsigned char* view,
 135     typename elfcpp::Elf_types<size>::Elf_Addr view_address,
 136     off_t view_size)
 137 {
 138   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
 139   const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
 140   Relocate relocate;
 141
 142   unsigned int local_count = relinfo->local_symbol_count;
 143   typename elfcpp::Elf_types<size>::Elf_Addr *local_values = relinfo->values;
 144   Symbol** global_syms = relinfo->symbols;
 145
 146   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
 147     {
 148       Reltype reloc(prelocs);
 149
 150       off_t offset = reloc.get_r_offset();
 151
 152       typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info();
 153       unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
 154       unsigned int r_type = elfcpp::elf_r_type<size>(r_info);
 155
 156       Sized_symbol<size>* sym;
 157       typename elfcpp::Elf_types<size>::Elf_Addr value;
 158
 159       if (r_sym < local_count)
 160         {
 161           sym = NULL;
 162           value = local_values[r_sym];
 163         }
 164       else
 165         {
 166           Symbol* gsym = global_syms[r_sym - local_count];
 167           assert(gsym != NULL);
 168           if (gsym->is_forwarder())
 169             gsym = relinfo->symtab->resolve_forwards(gsym);
 170
 171           sym = static_cast<Sized_symbol<size>*>(gsym);
 172           value = sym->value();
 173         }
 174
 175       if (!relocate.relocate(relinfo, target, i, reloc, r_type, sym, value,
 176                              view + offset, view_address + offset, view_size))
 177         continue;
 178
 179       if (offset < 0 || offset >= view_size)
 180         {
 181           fprintf(stderr, _("%s: %s: reloc has bad offset %zu\n"),
 182                   program_name, relinfo->location(i, offset).c_str(),
 183                   static_cast<size_t>(offset));
 184           gold_exit(false);
 185         }
 186
 187       if (sym != NULL
 188           && sym->is_undefined()
 189           && sym->binding() != elfcpp::STB_WEAK)
 190         {
 191           fprintf(stderr, _("%s: %s: undefined reference to '%s'\n"),
 192                   program_name, relinfo->location(i, offset).c_str(),
 193                   sym->name());
 194           // gold_exit(false);
 195         }
 196     }
 197 }
 198
 199 } // End namespace gold.
 200
 201 #endif // !defined(GOLD_TARGET_RELOC_H)