// copy-relocs.h -- handle COPY relocations for gold -*- C++ -*-
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// copy-relocs.h -- handle COPY relocations for gold -*- C++ -*-
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// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
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// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
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// Written by Ian Lance Taylor <iant@google.com>.
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// Written by Ian Lance Taylor <iant@google.com>.
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// This file is part of gold.
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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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// 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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// 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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// 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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// (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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// 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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// 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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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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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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// 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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// 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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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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// MA 02110-1301, USA.
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#ifndef GOLD_COPY_RELOCS_H
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#ifndef GOLD_COPY_RELOCS_H
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#define GOLD_COPY_RELOCS_H
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#define GOLD_COPY_RELOCS_H
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#include "elfcpp.h"
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#include "elfcpp.h"
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#include "reloc-types.h"
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#include "reloc-types.h"
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#include "output.h"
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#include "output.h"
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namespace gold
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namespace gold
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{
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{
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// This class is used to manage COPY relocations. We try to avoid
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// This class is used to manage COPY relocations. We try to avoid
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// them when possible. A COPY relocation may be required when an
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// them when possible. A COPY relocation may be required when an
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// executable refers to a variable defined in a shared library. COPY
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// executable refers to a variable defined in a shared library. COPY
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// relocations are problematic because they tie the executable to the
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// relocations are problematic because they tie the executable to the
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// exact size of the variable in the shared library. We can avoid
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// exact size of the variable in the shared library. We can avoid
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// them if all the references to the variable are in a writeable
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// them if all the references to the variable are in a writeable
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// section. In that case we can simply use dynamic relocations.
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// section. In that case we can simply use dynamic relocations.
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// However, when scanning relocs, we don't know when we see the
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// However, when scanning relocs, we don't know when we see the
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// relocation whether we will be forced to use a COPY relocation or
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// relocation whether we will be forced to use a COPY relocation or
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// not. So we have to save the relocation during the reloc scanning,
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// not. So we have to save the relocation during the reloc scanning,
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// and then emit it as a dynamic relocation if necessary. This class
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// and then emit it as a dynamic relocation if necessary. This class
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// implements that. It is used by the target specific code.
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// implements that. It is used by the target specific code.
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// The template parameter SH_TYPE is the type of the reloc section to
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// The template parameter SH_TYPE is the type of the reloc section to
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// be used for COPY relocs: elfcpp::SHT_REL or elfcpp::SHT_RELA.
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// be used for COPY relocs: elfcpp::SHT_REL or elfcpp::SHT_RELA.
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template<int sh_type, int size, bool big_endian>
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template<int sh_type, int size, bool big_endian>
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class Copy_relocs
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class Copy_relocs
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{
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{
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private:
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private:
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typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reloc;
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typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reloc;
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public:
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public:
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Copy_relocs(unsigned int copy_reloc_type)
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Copy_relocs(unsigned int copy_reloc_type)
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: copy_reloc_type_(copy_reloc_type), dynbss_(NULL), entries_()
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: copy_reloc_type_(copy_reloc_type), dynbss_(NULL), entries_()
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{ }
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{ }
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// This is called while scanning relocs if we see a relocation
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// This is called while scanning relocs if we see a relocation
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// against a symbol which may force us to generate a COPY reloc.
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// against a symbol which may force us to generate a COPY reloc.
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// SYM is the symbol. OBJECT is the object whose relocs we are
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// SYM is the symbol. OBJECT is the object whose relocs we are
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// scanning. The relocation is being applied to section SHNDX in
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// scanning. The relocation is being applied to section SHNDX in
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// OBJECT. OUTPUT_SECTION is the output section where section SHNDX
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// OBJECT. OUTPUT_SECTION is the output section where section SHNDX
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// will wind up. REL is the reloc itself. The Output_data_reloc
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// will wind up. REL is the reloc itself. The Output_data_reloc
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// section is where the dynamic relocs are put.
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// section is where the dynamic relocs are put.
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void
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void
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copy_reloc(Symbol_table*, Layout*, Sized_symbol<size>* sym,
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copy_reloc(Symbol_table*, Layout*, Sized_symbol<size>* sym,
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Sized_relobj<size, big_endian>* object,
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Sized_relobj<size, big_endian>* object,
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unsigned int shndx, Output_section* output_section,
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unsigned int shndx, Output_section* output_section,
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const Reloc& rel,
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const Reloc& rel,
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Output_data_reloc<sh_type, true, size, big_endian>*);
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Output_data_reloc<sh_type, true, size, big_endian>*);
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// Return whether there are any saved relocations.
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// Return whether there are any saved relocations.
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bool
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bool
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any_saved_relocs() const
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any_saved_relocs() const
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{ return !this->entries_.empty(); }
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{ return !this->entries_.empty(); }
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// Emit any saved relocations which turn out to be needed. This is
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// Emit any saved relocations which turn out to be needed. This is
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// called after all the relocs have been scanned.
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// called after all the relocs have been scanned.
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void
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void
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emit(Output_data_reloc<sh_type, true, size, big_endian>*);
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emit(Output_data_reloc<sh_type, true, size, big_endian>*);
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private:
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private:
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typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
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typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
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typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend;
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typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend;
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// This POD class holds the relocations we are saving. We will emit
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// This POD class holds the relocations we are saving. We will emit
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// these relocations if it turns out that the symbol does not
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// these relocations if it turns out that the symbol does not
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// require a COPY relocation.
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// require a COPY relocation.
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class Copy_reloc_entry
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class Copy_reloc_entry
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{
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{
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public:
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public:
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Copy_reloc_entry(Symbol* sym, unsigned int reloc_type,
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Copy_reloc_entry(Symbol* sym, unsigned int reloc_type,
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Sized_relobj<size, big_endian>* relobj,
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Sized_relobj<size, big_endian>* relobj,
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unsigned int shndx,
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unsigned int shndx,
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Output_section* output_section,
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Output_section* output_section,
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Address address, Addend addend)
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Address address, Addend addend)
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: sym_(sym), reloc_type_(reloc_type), relobj_(relobj),
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: sym_(sym), reloc_type_(reloc_type), relobj_(relobj),
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shndx_(shndx), output_section_(output_section),
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shndx_(shndx), output_section_(output_section),
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address_(address), addend_(addend)
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address_(address), addend_(addend)
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{ }
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{ }
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// Emit this reloc if appropriate. This is called after we have
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// Emit this reloc if appropriate. This is called after we have
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// scanned all the relocations, so we know whether we emitted a
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// scanned all the relocations, so we know whether we emitted a
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// COPY relocation for SYM_.
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// COPY relocation for SYM_.
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void
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void
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emit(Output_data_reloc<sh_type, true, size, big_endian>*);
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emit(Output_data_reloc<sh_type, true, size, big_endian>*);
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private:
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private:
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Symbol* sym_;
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Symbol* sym_;
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unsigned int reloc_type_;
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unsigned int reloc_type_;
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Sized_relobj<size, big_endian>* relobj_;
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Sized_relobj<size, big_endian>* relobj_;
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unsigned int shndx_;
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unsigned int shndx_;
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Output_section* output_section_;
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Output_section* output_section_;
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Address address_;
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Address address_;
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Addend addend_;
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Addend addend_;
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};
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};
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// A list of relocs to be saved.
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// A list of relocs to be saved.
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typedef std::vector<Copy_reloc_entry> Copy_reloc_entries;
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typedef std::vector<Copy_reloc_entry> Copy_reloc_entries;
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// Return whether we need a COPY reloc.
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// Return whether we need a COPY reloc.
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bool
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bool
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need_copy_reloc(Sized_symbol<size>* gsym,
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need_copy_reloc(Sized_symbol<size>* gsym,
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Sized_relobj<size, big_endian>* object,
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Sized_relobj<size, big_endian>* object,
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unsigned int shndx) const;
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unsigned int shndx) const;
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// Emit a COPY reloc.
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// Emit a COPY reloc.
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void
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void
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emit_copy_reloc(Symbol_table*, Layout*, Sized_symbol<size>*,
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emit_copy_reloc(Symbol_table*, Layout*, Sized_symbol<size>*,
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Output_data_reloc<sh_type, true, size, big_endian>*);
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Output_data_reloc<sh_type, true, size, big_endian>*);
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// Add a COPY reloc to the dynamic reloc section.
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// Add a COPY reloc to the dynamic reloc section.
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void
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void
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add_copy_reloc(Symbol*, section_size_type,
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add_copy_reloc(Symbol*, section_size_type,
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Output_data_reloc<sh_type, true, size, big_endian>*);
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Output_data_reloc<sh_type, true, size, big_endian>*);
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// Save a reloc against SYM for possible emission later.
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// Save a reloc against SYM for possible emission later.
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void
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void
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save(Symbol*, Sized_relobj<size, big_endian>*, unsigned int shndx,
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save(Symbol*, Sized_relobj<size, big_endian>*, unsigned int shndx,
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Output_section*, const Reloc& rel);
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Output_section*, const Reloc& rel);
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// The target specific relocation type of the COPY relocation.
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// The target specific relocation type of the COPY relocation.
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const unsigned int copy_reloc_type_;
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const unsigned int copy_reloc_type_;
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// The dynamic BSS data which goes into the .bss section. This is
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// The dynamic BSS data which goes into the .bss section. This is
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// where variables which require COPY relocations are placed.
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// where variables which require COPY relocations are placed.
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Output_data_space* dynbss_;
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Output_data_space* dynbss_;
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// The list of relocs we are saving.
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// The list of relocs we are saving.
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Copy_reloc_entries entries_;
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Copy_reloc_entries entries_;
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};
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};
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} // End namespace gold.
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} // End namespace gold.
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#endif // !defined(GOLD_COPY_RELOCS_H)
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#endif // !defined(GOLD_COPY_RELOCS_H)
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