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 "elfcpp.h" 25 #include "dynobj.h" 26 #include "symtab.h" 27 #include "output.h" 28 #include "target.h" 29 30 namespace gold 31 { 32 33 // Return whether NAME is a local label name. This is used to implement the 34 // --discard-locals options and can be overriden by children classes to 35 // implement system-specific behaviour. The logic here is the same as that 36 // in _bfd_elf_is_local_label_name(). 37 38 bool 39 Target::do_is_local_label_name(const char* name) const 40 { 41 // Normal local symbols start with ``.L''. 42 if (name[0] == '.' && name[1] == 'L') 43 return true; 44 45 // At least some SVR4 compilers (e.g., UnixWare 2.1 cc) generate 46 // DWARF debugging symbols starting with ``..''. 47 if (name[0] == '.' && name[1] == '.') 48 return true; 49 50 // gcc will sometimes generate symbols beginning with ``_.L_'' when 51 // emitting DWARF debugging output. I suspect this is actually a 52 // small bug in gcc (it calls ASM_OUTPUT_LABEL when it should call 53 // ASM_GENERATE_INTERNAL_LABEL, and this causes the leading 54 // underscore to be emitted on some ELF targets). For ease of use, 55 // we treat such symbols as local. 56 if (name[0] == '_' && name[1] == '.' && name[2] == 'L' && name[3] == '_') 57 return true; 58 59 return false; 60 } 61 62 // Implementations of methods Target::do_make_elf_object are almost identical 63 // except for the address sizes and endianities. So we extract this 64 // into a template. 65 66 template<int size, bool big_endian> 67 inline Object* 68 Target::do_make_elf_object_implementation( 69 const std::string& name, 70 Input_file* input_file, 71 off_t offset, 72 const elfcpp::Ehdr<size, big_endian>& ehdr) 73 { 74 int et = ehdr.get_e_type(); 75 if (et == elfcpp::ET_REL) 76 { 77 Sized_relobj<size, big_endian>* obj = 78 new Sized_relobj<size, big_endian>(name, input_file, offset, ehdr); 79 obj->setup(); 80 return obj; 81 } 82 else if (et == elfcpp::ET_DYN) 83 { 84 Sized_dynobj<size, big_endian>* obj = 85 new Sized_dynobj<size, big_endian>(name, input_file, offset, ehdr); 86 obj->setup(); 87 return obj; 88 } 89 else 90 { 91 gold_error(_("%s: unsupported ELF file type %d"), 92 name.c_str(), et); 93 return NULL; 94 } 95 } 96 97 // Make an ELF object called NAME by reading INPUT_FILE at OFFSET. EHDR 98 // is the ELF header of the object. There are four versions of this 99 // for different address sizes and endianities. 100 101 #ifdef HAVE_TARGET_32_LITTLE 102 Object* 103 Target::do_make_elf_object(const std::string& name, Input_file* input_file, 104 off_t offset, const elfcpp::Ehdr<32, false>& ehdr) 105 { 106 return this->do_make_elf_object_implementation<32, false>(name, input_file, 107 offset, ehdr); 108 } 109 #endif 110 111 #ifdef HAVE_TARGET_32_BIG 112 Object* 113 Target::do_make_elf_object(const std::string& name, Input_file* input_file, 114 off_t offset, const elfcpp::Ehdr<32, true>& ehdr) 115 { 116 return this->do_make_elf_object_implementation<32, true>(name, input_file, 117 offset, ehdr); 118 } 119 #endif 120 121 #ifdef HAVE_TARGET_64_LITTLE 122 Object* 123 Target::do_make_elf_object(const std::string& name, Input_file* input_file, 124 off_t offset, const elfcpp::Ehdr<64, false>& ehdr) 125 { 126 return this->do_make_elf_object_implementation<64, false>(name, input_file, 127 offset, ehdr); 128 } 129 #endif 130 131 #ifdef HAVE_TARGET_64_BIG 132 Object* 133 Target::do_make_elf_object(const std::string& name, Input_file* input_file, 134 off_t offset, const elfcpp::Ehdr<64, true>& ehdr) 135 { 136 return this->do_make_elf_object_implementation<64, true>(name, input_file, 137 offset, ehdr); 138 } 139 #endif 140 141 Output_section* 142 Target::do_make_output_section(const char* name, elfcpp::Elf_Word type, 143 elfcpp::Elf_Xword flags) 144 { 145 return new Output_section(name, type, flags); 146 } 147 148 // Default for whether a reloc is a call to a non-split function is 149 // whether the symbol is a function. 150 151 bool 152 Target::do_is_call_to_non_split(const Symbol* sym, unsigned int) const 153 { 154 return sym->type() == elfcpp::STT_FUNC; 155 } 156 157 // Default conversion for -fsplit-stack is to give an error. 158 159 void 160 Target::do_calls_non_split(Relobj* object, unsigned int, section_offset_type, 161 section_size_type, unsigned char*, section_size_type, 162 std::string*, std::string*) const 163 { 164 static bool warned; 165 if (!warned) 166 { 167 gold_error(_("linker does not include stack split support " 168 "required by %s"), 169 object->name().c_str()); 170 warned = true; 171 } 172 } 173 174 // Return whether BYTES/LEN matches VIEW/VIEW_SIZE at OFFSET. 175 176 bool 177 Target::match_view(const unsigned char* view, section_size_type view_size, 178 section_offset_type offset, const char* bytes, 179 size_t len) const 180 { 181 if (offset + len > view_size) 182 return false; 183 return memcmp(view + offset, bytes, len) == 0; 184 } 185 186 // Set the contents of a VIEW/VIEW_SIZE to nops starting at OFFSET 187 // for LEN bytes. 188 189 void 190 Target::set_view_to_nop(unsigned char* view, section_size_type view_size, 191 section_offset_type offset, size_t len) const 192 { 193 gold_assert(offset >= 0 && offset + len <= view_size); 194 if (!this->has_code_fill()) 195 memset(view + offset, 0, len); 196 else 197 { 198 std::string fill = this->code_fill(len); 199 memcpy(view + offset, fill.data(), len); 200 } 201 } 202 203 } // End namespace gold. 204