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// copy-relocs.cc -- handle COPY relocations for gold.
// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@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 "symtab.h"
#include "copy-relocs.h"
namespace gold
{
// Copy_relocs::Copy_reloc_entry methods.
// Emit the reloc if appropriate.
template<int sh_type, int size, bool big_endian>
void
Copy_relocs<sh_type, size, big_endian>::Copy_reloc_entry::emit(
Output_data_reloc<sh_type, true, size, big_endian>* reloc_section)
{
// If the symbol is no longer defined in a dynamic object, then we
// emitted a COPY relocation, and we do not want to emit this
// dynamic relocation.
if (this->sym_->is_from_dynobj())
reloc_section->add_global(this->sym_, this->reloc_type_,
this->output_section_, this->relobj_,
this->shndx_, this->address_,
this->addend_);
}
// Copy_relocs methods.
// Handle a relocation against a symbol which may force us to generate
// a COPY reloc.
template<int sh_type, int size, bool big_endian>
void
Copy_relocs<sh_type, size, big_endian>::copy_reloc(
Symbol_table* symtab,
Layout* layout,
Sized_symbol<size>* sym,
Relobj* object,
unsigned int shndx,
Output_section *output_section,
const Reloc& rel,
Output_data_reloc<sh_type, true, size, big_endian>* reloc_section)
{
if (this->need_copy_reloc(sym, object, shndx))
this->emit_copy_reloc(symtab, layout, sym, reloc_section);
else
{
// We may not need a COPY relocation. Save this relocation to
// possibly be emitted later.
this->save(sym, object, shndx, output_section, rel);
}
}
// Return whether we need a COPY reloc for a relocation against SYM.
// The relocation is begin applied to section SHNDX in OBJECT.
template<int sh_type, int size, bool big_endian>
bool
Copy_relocs<sh_type, size, big_endian>::need_copy_reloc(
Sized_symbol<size>* sym,
Relobj* object,
unsigned int shndx) const
{
// FIXME: Handle -z nocopyrelocs.
if (sym->symsize() == 0)
return false;
// If this is a readonly section, then we need a COPY reloc.
// Otherwise we can use a dynamic reloc. Note that calling
// section_flags here can be slow, as the information is not cached;
// fortunately we shouldn't see too many potential COPY relocs.
if ((object->section_flags(shndx) & elfcpp::SHF_WRITE) == 0)
return true;
return false;
}
// Emit a COPY relocation for SYM.
template<int sh_type, int size, bool big_endian>
void
Copy_relocs<sh_type, size, big_endian>::emit_copy_reloc(
Symbol_table* symtab,
Layout* layout,
Sized_symbol<size>* sym,
Output_data_reloc<sh_type, true, size, big_endian>* reloc_section)
{
typename elfcpp::Elf_types<size>::Elf_WXword symsize = sym->symsize();
// There is no defined way to determine the required alignment of
// the symbol. We know that the symbol is defined in a dynamic
// object. We start with the alignment of the section in which it
// is defined; presumably we do not require an alignment larger than
// that. Then we reduce that alignment if the symbol is not aligned
// within the section.
gold_assert(sym->is_from_dynobj());
typename elfcpp::Elf_types<size>::Elf_WXword addralign =
sym->object()->section_addralign(sym->shndx());
typename Sized_symbol<size>::Value_type value = sym->value();
while ((value & (addralign - 1)) != 0)
addralign >>= 1;
if (this->dynbss_ == NULL)
{
this->dynbss_ = new Output_data_space(addralign);
layout->add_output_section_data(".bss",
elfcpp::SHT_NOBITS,
elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
this->dynbss_);
}
Output_data_space* dynbss = this->dynbss_;
if (addralign > dynbss->addralign())
dynbss->set_space_alignment(addralign);
section_size_type dynbss_size =
convert_to_section_size_type(dynbss->current_data_size());
dynbss_size = align_address(dynbss_size, addralign);
section_size_type offset = dynbss_size;
dynbss->set_current_data_size(dynbss_size + symsize);
// Define the symbol as being copied.
symtab->define_with_copy_reloc(sym, dynbss, offset);
// Add the COPY relocation to the dynamic reloc section.
this->add_copy_reloc(sym, offset, reloc_section);
}
// Add a COPY relocation for SYM to RELOC_SECTION.
template<int sh_type, int size, bool big_endian>
void
Copy_relocs<sh_type, size, big_endian>::add_copy_reloc(
Symbol* sym,
section_size_type offset,
Output_data_reloc<sh_type, true, size, big_endian>* reloc_section)
{
reloc_section->add_global(sym, this->copy_reloc_type_, this->dynbss_,
offset, 0);
}
// Save a relocation to possibly be emitted later.
template<int sh_type, int size, bool big_endian>
void
Copy_relocs<sh_type, size, big_endian>::save(Symbol* sym, Relobj* object,
unsigned int shndx,
Output_section* output_section,
const Reloc& rel)
{
unsigned int reloc_type = elfcpp::elf_r_type<size>(rel.get_r_info());
typename elfcpp::Elf_types<size>::Elf_Addr addend =
Reloc_types<sh_type, size, big_endian>::get_reloc_addend_noerror(&rel);
this->entries_.push_back(Copy_reloc_entry(sym, reloc_type, object, shndx,
output_section, rel.get_r_offset(),
addend));
}
// Emit any saved relocs.
template<int sh_type, int size, bool big_endian>
void
Copy_relocs<sh_type, size, big_endian>::emit(
Output_data_reloc<sh_type, true, size, big_endian>* reloc_section)
{
for (typename Copy_reloc_entries::iterator p = this->entries_.begin();
p != this->entries_.end();
++p)
p->emit(reloc_section);
// We no longer need the saved information.
this->entries_.clear();
}
// Instantiate the templates we need.
#ifdef HAVE_TARGET_32_LITTLE
template
class Copy_relocs<elfcpp::SHT_REL, 32, false>;
template
class Copy_relocs<elfcpp::SHT_RELA, 32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Copy_relocs<elfcpp::SHT_REL, 32, true>;
template
class Copy_relocs<elfcpp::SHT_RELA, 32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Copy_relocs<elfcpp::SHT_REL, 64, false>;
template
class Copy_relocs<elfcpp::SHT_RELA, 64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Copy_relocs<elfcpp::SHT_REL, 64, true>;
template
class Copy_relocs<elfcpp::SHT_RELA, 64, true>;
#endif
} // End namespace gold.
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