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[/] [open8_urisc/] [trunk/] [gnu/] [binutils/] [gold/] [copy-relocs.h] - Blame information for rev 98

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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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// Written by Ian Lance Taylor <iant@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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#ifndef 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 "reloc-types.h"
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#include "output.h"
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namespace gold
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{
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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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// 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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// 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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// 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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// 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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// 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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// 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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template<int sh_type, int size, bool big_endian>
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class Copy_relocs
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{
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 private:
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  typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reloc;
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 public:
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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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  { }
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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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  // 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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  // 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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  // section is where the dynamic relocs are put.
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  void
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  copy_reloc(Symbol_table*, Layout*, Sized_symbol<size>* sym,
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             Sized_relobj_file<size, big_endian>* object,
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             unsigned int shndx, Output_section* output_section,
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             const Reloc& rel,
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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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  bool
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  any_saved_relocs() const
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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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  // called after all the relocs have been scanned.
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  void
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  emit(Output_data_reloc<sh_type, true, size, big_endian>*);
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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 Addend;
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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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  // require a COPY relocation.
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  class Copy_reloc_entry
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  {
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   public:
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    Copy_reloc_entry(Symbol* sym, unsigned int reloc_type,
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                     Sized_relobj_file<size, big_endian>* relobj,
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                     unsigned int shndx,
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                     Output_section* output_section,
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                     Address address, Addend addend)
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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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        address_(address), addend_(addend)
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    { }
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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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    // COPY relocation for SYM_.
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    void
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    emit(Output_data_reloc<sh_type, true, size, big_endian>*);
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   private:
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    Symbol* sym_;
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    unsigned int reloc_type_;
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    Sized_relobj_file<size, big_endian>* relobj_;
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    unsigned int shndx_;
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    Output_section* output_section_;
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    Address address_;
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    Addend addend_;
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  };
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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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  // Return whether we need a COPY reloc.
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  bool
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  need_copy_reloc(Sized_symbol<size>* gsym,
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                  Sized_relobj_file<size, big_endian>* object,
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                  unsigned int shndx) const;
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  // Emit a COPY reloc.
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  void
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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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  // Add a COPY reloc to the dynamic reloc section.
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  void
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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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  // Save a reloc against SYM for possible emission later.
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  void
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  save(Symbol*, Sized_relobj_file<size, big_endian>*, unsigned int shndx,
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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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  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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  // where variables which require COPY relocations are placed.
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  Output_data_space* dynbss_;
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  // The list of relocs we are saving.
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  Copy_reloc_entries entries_;
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};
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} // End namespace gold.
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#endif // !defined(GOLD_COPY_RELOCS_H)

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