262 lines
7.3 KiB
C++
262 lines
7.3 KiB
C++
// target.cc -- target support for gold.
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// Copyright (C) 2009-2022 Free Software Foundation, Inc.
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// Written by Doug Kwan <dougkwan@google.com>.
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// This file is part of gold.
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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#include "gold.h"
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#include "elfcpp.h"
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#include "dynobj.h"
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#include "symtab.h"
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#include "output.h"
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#include "target.h"
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namespace gold
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{
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// Return whether NAME is a local label name. This is used to implement the
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// --discard-locals options and can be overridden by child classes to
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// implement system-specific behaviour. The logic here is the same as that
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// in _bfd_elf_is_local_label_name().
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bool
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Target::do_is_local_label_name(const char* name) const
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{
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// Normal local symbols start with ``.L''.
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if (name[0] == '.' && name[1] == 'L')
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return true;
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// At least some SVR4 compilers (e.g., UnixWare 2.1 cc) generate
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// DWARF debugging symbols starting with ``..''.
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if (name[0] == '.' && name[1] == '.')
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return true;
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// gcc will sometimes generate symbols beginning with ``_.L_'' when
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// emitting DWARF debugging output. I suspect this is actually a
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// small bug in gcc (it calls ASM_OUTPUT_LABEL when it should call
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// ASM_GENERATE_INTERNAL_LABEL, and this causes the leading
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// underscore to be emitted on some ELF targets). For ease of use,
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// we treat such symbols as local.
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if (name[0] == '_' && name[1] == '.' && name[2] == 'L' && name[3] == '_')
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return true;
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return false;
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}
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// Implementations of methods Target::do_make_elf_object are almost identical
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// except for the address sizes and endianities. So we extract this
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// into a template.
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template<int size, bool big_endian>
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inline Object*
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Target::do_make_elf_object_implementation(
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const std::string& name,
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Input_file* input_file,
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off_t offset,
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const elfcpp::Ehdr<size, big_endian>& ehdr)
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{
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int et = ehdr.get_e_type();
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// ET_EXEC files are valid input for --just-symbols/-R,
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// and we treat them as relocatable objects.
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if (et == elfcpp::ET_REL
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|| (et == elfcpp::ET_EXEC && input_file->just_symbols()))
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{
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Sized_relobj_file<size, big_endian>* obj =
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new Sized_relobj_file<size, big_endian>(name, input_file, offset, ehdr);
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obj->setup();
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return obj;
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}
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else if (et == elfcpp::ET_DYN)
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{
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Sized_dynobj<size, big_endian>* obj =
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new Sized_dynobj<size, big_endian>(name, input_file, offset, ehdr);
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obj->setup();
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return obj;
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}
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else
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{
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gold_error(_("%s: unsupported ELF file type %d"),
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name.c_str(), et);
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return NULL;
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}
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}
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// Make an ELF object called NAME by reading INPUT_FILE at OFFSET. EHDR
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// is the ELF header of the object. There are four versions of this
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// for different address sizes and endianities.
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#ifdef HAVE_TARGET_32_LITTLE
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Object*
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Target::do_make_elf_object(const std::string& name, Input_file* input_file,
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off_t offset, const elfcpp::Ehdr<32, false>& ehdr)
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{
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return this->do_make_elf_object_implementation<32, false>(name, input_file,
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offset, ehdr);
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}
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#endif
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#ifdef HAVE_TARGET_32_BIG
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Object*
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Target::do_make_elf_object(const std::string& name, Input_file* input_file,
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off_t offset, const elfcpp::Ehdr<32, true>& ehdr)
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{
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return this->do_make_elf_object_implementation<32, true>(name, input_file,
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offset, ehdr);
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}
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#endif
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#ifdef HAVE_TARGET_64_LITTLE
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Object*
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Target::do_make_elf_object(const std::string& name, Input_file* input_file,
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off_t offset, const elfcpp::Ehdr<64, false>& ehdr)
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{
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return this->do_make_elf_object_implementation<64, false>(name, input_file,
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offset, ehdr);
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}
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#endif
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#ifdef HAVE_TARGET_64_BIG
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Object*
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Target::do_make_elf_object(const std::string& name, Input_file* input_file,
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off_t offset, const elfcpp::Ehdr<64, true>& ehdr)
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{
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return this->do_make_elf_object_implementation<64, true>(name, input_file,
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offset, ehdr);
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}
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#endif
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Output_section*
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Target::do_make_output_section(const char* name, elfcpp::Elf_Word type,
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elfcpp::Elf_Xword flags)
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{
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return new Output_section(name, type, flags);
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}
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// Default for whether a reloc is a call to a non-split function is
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// whether the symbol is a function.
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bool
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Target::do_is_call_to_non_split(const Symbol* sym, const unsigned char*,
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const unsigned char*, section_size_type) const
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{
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return sym->type() == elfcpp::STT_FUNC;
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}
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// Default conversion for -fsplit-stack is to give an error.
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void
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Target::do_calls_non_split(Relobj* object, unsigned int, section_offset_type,
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section_size_type, const unsigned char*, size_t,
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unsigned char*, section_size_type,
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std::string*, std::string*) const
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{
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static bool warned;
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if (!warned)
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{
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gold_error(_("linker does not include stack split support "
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"required by %s"),
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object->name().c_str());
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warned = true;
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}
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}
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// Return whether BYTES/LEN matches VIEW/VIEW_SIZE at OFFSET.
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bool
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Target::match_view(const unsigned char* view, section_size_type view_size,
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section_offset_type offset, const char* bytes,
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size_t len) const
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{
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if (offset + len > view_size)
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return false;
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return memcmp(view + offset, bytes, len) == 0;
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}
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// Set the contents of a VIEW/VIEW_SIZE to nops starting at OFFSET
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// for LEN bytes.
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void
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Target::set_view_to_nop(unsigned char* view, section_size_type view_size,
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section_offset_type offset, size_t len) const
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{
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gold_assert(offset >= 0 && offset + len <= view_size);
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if (!this->has_code_fill())
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memset(view + offset, 0, len);
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else
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{
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std::string fill = this->code_fill(len);
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memcpy(view + offset, fill.data(), len);
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}
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}
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// Return address and size to plug into eh_frame FDEs associated with a PLT.
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void
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Target::do_plt_fde_location(const Output_data* plt, unsigned char*,
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uint64_t* address, off_t* len) const
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{
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*address = plt->address();
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*len = plt->data_size();
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}
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// Class Sized_target.
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// Set the EI_OSABI field of the ELF header if requested.
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template<int size, bool big_endian>
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void
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Sized_target<size, big_endian>::do_adjust_elf_header(unsigned char* view,
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int len)
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{
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elfcpp::ELFOSABI osabi = this->osabi();
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if (osabi != elfcpp::ELFOSABI_NONE)
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{
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gold_assert(len == elfcpp::Elf_sizes<size>::ehdr_size);
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elfcpp::Ehdr<size, big_endian> ehdr(view);
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unsigned char e_ident[elfcpp::EI_NIDENT];
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memcpy(e_ident, ehdr.get_e_ident(), elfcpp::EI_NIDENT);
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e_ident[elfcpp::EI_OSABI] = osabi;
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elfcpp::Ehdr_write<size, big_endian> oehdr(view);
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oehdr.put_e_ident(e_ident);
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}
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}
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#ifdef HAVE_TARGET_32_LITTLE
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template
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class Sized_target<32, false>;
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#endif
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#ifdef HAVE_TARGET_32_BIG
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template
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class Sized_target<32, true>;
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#endif
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#ifdef HAVE_TARGET_64_LITTLE
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template
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class Sized_target<64, false>;
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#endif
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#ifdef HAVE_TARGET_64_BIG
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template
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class Sized_target<64, true>;
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#endif
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} // End namespace gold.
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