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 "output.h"
  27 #include "elfcpp.h"
  28
  29 namespace gold
  30 {
  31
  32 // Return whether NAME is a local label name.  This is used to implement the
  33 // --discard-locals options and can be overriden by children classes to
  34 // implement system-specific behaviour.  The logic here is the same as that
  35 // in _bfd_elf_is_local_label_name().
  36
  37 bool
  38 Target::do_is_local_label_name (const char* name) const
  39 {
  40   // Normal local symbols start with ``.L''.
  41   if (name[0] == '.' && name[1] == 'L')
  42     return true;
  43
  44   // At least some SVR4 compilers (e.g., UnixWare 2.1 cc) generate
  45   // DWARF debugging symbols starting with ``..''.
  46   if (name[0] == '.' && name[1] == '.')
  47     return true;
  48
  49   // gcc will sometimes generate symbols beginning with ``_.L_'' when
  50   // emitting DWARF debugging output.  I suspect this is actually a
  51   // small bug in gcc (it calls ASM_OUTPUT_LABEL when it should call
  52   // ASM_GENERATE_INTERNAL_LABEL, and this causes the leading
  53   // underscore to be emitted on some ELF targets).  For ease of use,
  54   // we treat such symbols as local.
  55   if (name[0] == '_' && name[1] == '.' && name[2] == 'L' && name[3] == '_')
  56     return true;
  57
  58   return false;
  59 }
  60
  61 // Implementations of methods Target::do_make_elf_object are almost identical
  62 // except for the address sizes and endianities.  So we extract this
  63 // into a template.
  64
  65 template<int size, bool big_endian>
  66 inline Object*
  67 Target::do_make_elf_object_implementation(
  68     const std::string& name,
  69     Input_file* input_file,
  70     off_t offset,
  71     const elfcpp::Ehdr<size, big_endian>& ehdr)
  72 {
  73   int et = ehdr.get_e_type();
  74   if (et == elfcpp::ET_REL)
  75     {
  76       Sized_relobj<size, big_endian>* obj =
  77         new Sized_relobj<size, big_endian>(name, input_file, offset, ehdr);
  78       obj->setup();
  79       return obj;
  80     }
  81   else if (et == elfcpp::ET_DYN)
  82     {
  83       Sized_dynobj<size, big_endian>* obj =
  84         new Sized_dynobj<size, big_endian>(name, input_file, offset, ehdr);
  85       obj->setup();
  86       return obj;
  87     }
  88   else
  89     {
  90       gold_error(_("%s: unsupported ELF file type %d"),
  91                  name.c_str(), et);
  92       return NULL;
  93     }
  94 }
  95
  96 // Make an ELF object called NAME by reading INPUT_FILE at OFFSET.  EHDR
  97 // is the ELF header of the object.  There are four versions of this
  98 // for different address sizes and endianities.
  99
 100 #ifdef HAVE_TARGET_32_LITTLE
 101 Object*
 102 Target::do_make_elf_object(const std::string& name, Input_file* input_file,
 103                            off_t offset, const elfcpp::Ehdr<32, false>& ehdr)
 104 {
 105   return this->do_make_elf_object_implementation<32, false>(name, input_file,
 106                                                             offset, ehdr);
 107 }
 108 #endif
 109
 110 #ifdef HAVE_TARGET_32_BIG
 111 Object*
 112 Target::do_make_elf_object(const std::string& name, Input_file* input_file,
 113                            off_t offset, const elfcpp::Ehdr<32, true>& ehdr)
 114 {
 115   return this->do_make_elf_object_implementation<32, true>(name, input_file,
 116                                                            offset, ehdr);
 117 }
 118 #endif
 119
 120 #ifdef HAVE_TARGET_64_LITTLE
 121 Object*
 122 Target::do_make_elf_object(const std::string& name, Input_file* input_file,
 123                            off_t offset, const elfcpp::Ehdr<64, false>& ehdr)
 124 {
 125   return this->do_make_elf_object_implementation<64, false>(name, input_file,
 126                                                             offset, ehdr);
 127 }
 128 #endif
 129
 130 #ifdef HAVE_TARGET_64_BIG
 131 Object*
 132 Target::do_make_elf_object(const std::string& name, Input_file* input_file,
 133                            off_t offset, const elfcpp::Ehdr<64, true>& ehdr)
 134 {
 135   return this->do_make_elf_object_implementation<64, true>(name, input_file,
 136                                                            offset, ehdr);
 137 }
 138 #endif
 139
 140 Output_section*
 141 Target::do_make_output_section(const char* name, elfcpp::Elf_Word type,
 142                                elfcpp::Elf_Xword flags)
 143 {
 144   return new Output_section(name, type, flags);
 145 }
 146
 147 // Default conversion for -fsplit-stack is to give an error.
 148
 149 void
 150 Target::do_calls_non_split(Relobj* object, unsigned int, section_offset_type,
 151                            section_size_type, unsigned char*, section_size_type,
 152                            std::string*, std::string*) const
 153 {
 154   static bool warned;
 155   if (!warned)
 156     {
 157       gold_error(_("linker does not include stack split support "
 158                    "required by %s"),
 159                  object->name().c_str());
 160       warned = true;
 161     }
 162 }
 163
 164 //  Return whether BYTES/LEN matches VIEW/VIEW_SIZE at OFFSET.
 165
 166 bool
 167 Target::match_view(const unsigned char* view, section_size_type view_size,
 168                    section_offset_type offset, const char* bytes,
 169                    size_t len) const
 170 {
 171   if (offset + len > view_size)
 172     return false;
 173   return memcmp(view + offset, bytes, len) == 0;
 174 }
 175
 176 // Set the contents of a VIEW/VIEW_SIZE to nops starting at OFFSET
 177 // for LEN bytes.
 178
 179 void
 180 Target::set_view_to_nop(unsigned char* view, section_size_type view_size,
 181                         section_offset_type offset, size_t len) const
 182 {
 183   gold_assert(offset >= 0 && offset + len <= view_size);
 184   if (!this->has_code_fill())
 185     memset(view + offset, 0, len);
 186   else
 187     {
 188       std::string fill = this->code_fill(len);
 189       memcpy(view + offset, fill.data(), len);
 190     }
 191 }
 192
 193 } // End namespace gold.