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