| // target.cc -- target support for gold. |
| |
| // Copyright (C) 2009-2021 Free Software Foundation, Inc. |
| // Written by Doug Kwan <dougkwan@google.com>. |
| |
| // This file is part of gold. |
| |
| // This program is free software; you can redistribute it and/or modify |
| // it under the terms of the GNU General Public License as published by |
| // the Free Software Foundation; either version 3 of the License, or |
| // (at your option) any later version. |
| |
| // This program is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // You should have received a copy of the GNU General Public License |
| // along with this program; if not, write to the Free Software |
| // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| // MA 02110-1301, USA. |
| |
| #include "gold.h" |
| #include "elfcpp.h" |
| #include "dynobj.h" |
| #include "symtab.h" |
| #include "output.h" |
| #include "target.h" |
| |
| namespace gold |
| { |
| |
| // Return whether NAME is a local label name. This is used to implement the |
| // --discard-locals options and can be overridden by child classes to |
| // implement system-specific behaviour. The logic here is the same as that |
| // in _bfd_elf_is_local_label_name(). |
| |
| bool |
| Target::do_is_local_label_name(const char* name) const |
| { |
| // Normal local symbols start with ``.L''. |
| if (name[0] == '.' && name[1] == 'L') |
| return true; |
| |
| // At least some SVR4 compilers (e.g., UnixWare 2.1 cc) generate |
| // DWARF debugging symbols starting with ``..''. |
| if (name[0] == '.' && name[1] == '.') |
| return true; |
| |
| // gcc will sometimes generate symbols beginning with ``_.L_'' when |
| // emitting DWARF debugging output. I suspect this is actually a |
| // small bug in gcc (it calls ASM_OUTPUT_LABEL when it should call |
| // ASM_GENERATE_INTERNAL_LABEL, and this causes the leading |
| // underscore to be emitted on some ELF targets). For ease of use, |
| // we treat such symbols as local. |
| if (name[0] == '_' && name[1] == '.' && name[2] == 'L' && name[3] == '_') |
| return true; |
| |
| return false; |
| } |
| |
| // Implementations of methods Target::do_make_elf_object are almost identical |
| // except for the address sizes and endianities. So we extract this |
| // into a template. |
| |
| template<int size, bool big_endian> |
| inline Object* |
| Target::do_make_elf_object_implementation( |
| const std::string& name, |
| Input_file* input_file, |
| off_t offset, |
| const elfcpp::Ehdr<size, big_endian>& ehdr) |
| { |
| int et = ehdr.get_e_type(); |
| // ET_EXEC files are valid input for --just-symbols/-R, |
| // and we treat them as relocatable objects. |
| if (et == elfcpp::ET_REL |
| || (et == elfcpp::ET_EXEC && input_file->just_symbols())) |
| { |
| Sized_relobj_file<size, big_endian>* obj = |
| new Sized_relobj_file<size, big_endian>(name, input_file, offset, ehdr); |
| obj->setup(); |
| return obj; |
| } |
| else if (et == elfcpp::ET_DYN) |
| { |
| Sized_dynobj<size, big_endian>* obj = |
| new Sized_dynobj<size, big_endian>(name, input_file, offset, ehdr); |
| obj->setup(); |
| return obj; |
| } |
| else |
| { |
| gold_error(_("%s: unsupported ELF file type %d"), |
| name.c_str(), et); |
| return NULL; |
| } |
| } |
| |
| // Make an ELF object called NAME by reading INPUT_FILE at OFFSET. EHDR |
| // is the ELF header of the object. There are four versions of this |
| // for different address sizes and endianities. |
| |
| #ifdef HAVE_TARGET_32_LITTLE |
| Object* |
| Target::do_make_elf_object(const std::string& name, Input_file* input_file, |
| off_t offset, const elfcpp::Ehdr<32, false>& ehdr) |
| { |
| return this->do_make_elf_object_implementation<32, false>(name, input_file, |
| offset, ehdr); |
| } |
| #endif |
| |
| #ifdef HAVE_TARGET_32_BIG |
| Object* |
| Target::do_make_elf_object(const std::string& name, Input_file* input_file, |
| off_t offset, const elfcpp::Ehdr<32, true>& ehdr) |
| { |
| return this->do_make_elf_object_implementation<32, true>(name, input_file, |
| offset, ehdr); |
| } |
| #endif |
| |
| #ifdef HAVE_TARGET_64_LITTLE |
| Object* |
| Target::do_make_elf_object(const std::string& name, Input_file* input_file, |
| off_t offset, const elfcpp::Ehdr<64, false>& ehdr) |
| { |
| return this->do_make_elf_object_implementation<64, false>(name, input_file, |
| offset, ehdr); |
| } |
| #endif |
| |
| #ifdef HAVE_TARGET_64_BIG |
| Object* |
| Target::do_make_elf_object(const std::string& name, Input_file* input_file, |
| off_t offset, const elfcpp::Ehdr<64, true>& ehdr) |
| { |
| return this->do_make_elf_object_implementation<64, true>(name, input_file, |
| offset, ehdr); |
| } |
| #endif |
| |
| Output_section* |
| Target::do_make_output_section(const char* name, elfcpp::Elf_Word type, |
| elfcpp::Elf_Xword flags) |
| { |
| return new Output_section(name, type, flags); |
| } |
| |
| // Default for whether a reloc is a call to a non-split function is |
| // whether the symbol is a function. |
| |
| bool |
| Target::do_is_call_to_non_split(const Symbol* sym, const unsigned char*, |
| const unsigned char*, section_size_type) const |
| { |
| return sym->type() == elfcpp::STT_FUNC; |
| } |
| |
| // Default conversion for -fsplit-stack is to give an error. |
| |
| void |
| Target::do_calls_non_split(Relobj* object, unsigned int, section_offset_type, |
| section_size_type, const unsigned char*, size_t, |
| unsigned char*, section_size_type, |
| std::string*, std::string*) const |
| { |
| static bool warned; |
| if (!warned) |
| { |
| gold_error(_("linker does not include stack split support " |
| "required by %s"), |
| object->name().c_str()); |
| warned = true; |
| } |
| } |
| |
| // Return whether BYTES/LEN matches VIEW/VIEW_SIZE at OFFSET. |
| |
| bool |
| Target::match_view(const unsigned char* view, section_size_type view_size, |
| section_offset_type offset, const char* bytes, |
| size_t len) const |
| { |
| if (offset + len > view_size) |
| return false; |
| return memcmp(view + offset, bytes, len) == 0; |
| } |
| |
| // Set the contents of a VIEW/VIEW_SIZE to nops starting at OFFSET |
| // for LEN bytes. |
| |
| void |
| Target::set_view_to_nop(unsigned char* view, section_size_type view_size, |
| section_offset_type offset, size_t len) const |
| { |
| gold_assert(offset >= 0 && offset + len <= view_size); |
| if (!this->has_code_fill()) |
| memset(view + offset, 0, len); |
| else |
| { |
| std::string fill = this->code_fill(len); |
| memcpy(view + offset, fill.data(), len); |
| } |
| } |
| |
| // Return address and size to plug into eh_frame FDEs associated with a PLT. |
| void |
| Target::do_plt_fde_location(const Output_data* plt, unsigned char*, |
| uint64_t* address, off_t* len) const |
| { |
| *address = plt->address(); |
| *len = plt->data_size(); |
| } |
| |
| // Class Sized_target. |
| |
| // Set the EI_OSABI field of the ELF header if requested. |
| |
| template<int size, bool big_endian> |
| void |
| Sized_target<size, big_endian>::do_adjust_elf_header(unsigned char* view, |
| int len) |
| { |
| elfcpp::ELFOSABI osabi = this->osabi(); |
| if (osabi != elfcpp::ELFOSABI_NONE) |
| { |
| gold_assert(len == elfcpp::Elf_sizes<size>::ehdr_size); |
| |
| elfcpp::Ehdr<size, big_endian> ehdr(view); |
| unsigned char e_ident[elfcpp::EI_NIDENT]; |
| memcpy(e_ident, ehdr.get_e_ident(), elfcpp::EI_NIDENT); |
| |
| e_ident[elfcpp::EI_OSABI] = osabi; |
| |
| elfcpp::Ehdr_write<size, big_endian> oehdr(view); |
| oehdr.put_e_ident(e_ident); |
| } |
| } |
| |
| #ifdef HAVE_TARGET_32_LITTLE |
| template |
| class Sized_target<32, false>; |
| #endif |
| |
| #ifdef HAVE_TARGET_32_BIG |
| template |
| class Sized_target<32, true>; |
| #endif |
| |
| #ifdef HAVE_TARGET_64_LITTLE |
| template |
| class Sized_target<64, false>; |
| #endif |
| |
| #ifdef HAVE_TARGET_64_BIG |
| template |
| class Sized_target<64, true>; |
| #endif |
| |
| } // End namespace gold. |