gold/target.cc

   1 // target.cc
   2
   3 // Copyright 2009 Free Software Foundation, Inc.
   4 // Written by Doug Kwan <dougkwan@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 #include "gold.h"
  24 #include "target.h"
  25 #include "dynobj.h"
  26 #include "elfcpp.h"
  27
  28 namespace gold
  29 {
  30
  31 // Return whether NAME is a local label name.  This is used to implement the
  32 // --discard-locals options and can be overriden by children classes to
  33 // implement system-specific behaviour.  The logic here is the same as that
  34 // in _bfd_elf_is_local_label_name().
  35
  36 bool
  37 Target::do_is_local_label_name (const char* name) const
  38 {
  39   // Normal local symbols start with ``.L''.
  40   if (name[0] == '.' && name[1] == 'L')
  41     return true;
  42
  43   // At least some SVR4 compilers (e.g., UnixWare 2.1 cc) generate
  44   // DWARF debugging symbols starting with ``..''.
  45   if (name[0] == '.' && name[1] == '.')
  46     return true;
  47
  48   // gcc will sometimes generate symbols beginning with ``_.L_'' when
  49   // emitting DWARF debugging output.  I suspect this is actually a
  50   // small bug in gcc (it calls ASM_OUTPUT_LABEL when it should call
  51   // ASM_GENERATE_INTERNAL_LABEL, and this causes the leading
  52   // underscore to be emitted on some ELF targets).  For ease of use,
  53   // we treat such symbols as local.
  54   if (name[0] == '_' && name[1] == '.' && name[2] == 'L' && name[3] == '_')
  55     return true;
  56
  57   return false;
  58 }
  59
  60 // Implementations of methods Target::do_make_elf_object are almost identical
  61 // except for the address sizes and endianities.  So we extract this
  62 // into a template.
  63
  64 template<int size, bool big_endian>
  65 inline Object*
  66 Target::do_make_elf_object_implementation(
  67     const std::string& name,
  68     Input_file* input_file,
  69     off_t offset,
  70     const elfcpp::Ehdr<size, big_endian>& ehdr)
  71 {
  72   int et = ehdr.get_e_type();
  73   if (et == elfcpp::ET_REL)
  74     {
  75       Sized_relobj<size, big_endian>* obj =
  76         new Sized_relobj<size, big_endian>(name, input_file, offset, ehdr);
  77       obj->setup();
  78       return obj;
  79     }
  80   else if (et == elfcpp::ET_DYN)
  81     {
  82       Sized_dynobj<size, big_endian>* obj =
  83         new Sized_dynobj<size, big_endian>(name, input_file, offset, ehdr);
  84       obj->setup();
  85       return obj;
  86     }
  87   else
  88     {
  89       gold_error(_("%s: unsupported ELF file type %d"),
  90                  name.c_str(), et);
  91       return NULL;
  92     }
  93 }
  94
  95 // Make an ELF object called NAME by reading INPUT_FILE at OFFSET.  EHDR
  96 // is the ELF header of the object.  There are four versions of this
  97 // for different address sizes and endianities.
  98
  99 #ifdef HAVE_TARGET_32_LITTLE
 100 Object*
 101 Target::do_make_elf_object(const std::string& name, Input_file* input_file,
 102                            off_t offset, const elfcpp::Ehdr<32, false>& ehdr)
 103 {
 104   return this->do_make_elf_object_implementation<32, false>(name, input_file,
 105                                                             offset, ehdr);
 106 }
 107 #endif
 108
 109 #ifdef HAVE_TARGET_32_BIG
 110 Object*
 111 Target::do_make_elf_object(const std::string& name, Input_file* input_file,
 112                            off_t offset, const elfcpp::Ehdr<32, true>& ehdr)
 113 {
 114   return this->do_make_elf_object_implementation<32, true>(name, input_file,
 115                                                            offset, ehdr);
 116 }
 117 #endif
 118
 119 #ifdef HAVE_TARGET_64_LITTLE
 120 Object*
 121 Target::do_make_elf_object(const std::string& name, Input_file* input_file,
 122                            off_t offset, const elfcpp::Ehdr<64, false>& ehdr)
 123 {
 124   return this->do_make_elf_object_implementation<64, false>(name, input_file,
 125                                                             offset, ehdr);
 126 }
 127 #endif
 128
 129 #ifdef HAVE_TARGET_64_BIG
 130 Object*
 131 Target::do_make_elf_object(const std::string& name, Input_file* input_file,
 132                            off_t offset, const elfcpp::Ehdr<64, true>& ehdr)
 133 {
 134   return this->do_make_elf_object_implementation<64, true>(name, input_file,
 135                                                            offset, ehdr);
 136 }
 137 #endif
 138
 139 // Default conversion for -fsplit-stack is to give an error.
 140
 141 void
 142 Target::do_calls_non_split(Relobj* object, unsigned int, section_offset_type,
 143                            section_size_type, unsigned char*, section_size_type,
 144                            std::string*, std::string*) const
 145 {
 146   static bool warned;
 147   if (!warned)
 148     {
 149       gold_error(_("linker does not include stack split support "
 150                    "required by %s"),
 151                  object->name().c_str());
 152       warned = true;
 153     }
 154 }
 155
 156 //  Return whether BYTES/LEN matches VIEW/VIEW_SIZE at OFFSET.
 157
 158 bool
 159 Target::match_view(const unsigned char* view, section_size_type view_size,
 160                    section_offset_type offset, const char* bytes,
 161                    size_t len) const
 162 {
 163   if (offset + len > view_size)
 164     return false;
 165   return memcmp(view + offset, bytes, len) == 0;
 166 }
 167
 168 // Set the contents of a VIEW/VIEW_SIZE to nops starting at OFFSET
 169 // for LEN bytes.
 170
 171 void
 172 Target::set_view_to_nop(unsigned char* view, section_size_type view_size,
 173                         section_offset_type offset, size_t len) const
 174 {
 175   gold_assert(offset >= 0 && offset + len <= view_size);
 176   if (!this->has_code_fill())
 177     memset(view + offset, 0, len);
 178   else
 179     {
 180       std::string fill = this->code_fill(len);
 181       memcpy(view + offset, fill.data(), len);
 182     }
 183 }
 184
 185 } // End namespace gold.