--- /dev/null
+// copy-relocs.h -- handle COPY relocations for gold -*- C++ -*-
+
+// 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.
+
+#ifndef GOLD_COPY_RELOCS_H
+#define GOLD_COPY_RELOCS_H
+
+#include "elfcpp.h"
+#include "reloc-types.h"
+#include "output.h"
+
+namespace gold
+{
+
+// This class is used to manage COPY relocations. We try to avoid
+// them when possible. A COPY relocation may be required when an
+// executable refers to a variable defined in a shared library. COPY
+// relocations are problematic because they tie the executable to the
+// exact size of the variable in the shared library. We can avoid
+// them if all the references to the variable are in a writeable
+// section. In that case we can simply use dynamic relocations.
+// However, when scanning relocs, we don't know when we see the
+// relocation whether we will be forced to use a COPY relocation or
+// not. So we have to save the relocation during the reloc scanning,
+// and then emit it as a dynamic relocation if necessary. This class
+// implements that. It is used by the target specific code.
+
+// The template parameter SH_TYPE is the type of the reloc section to
+// be used for COPY relocs: elfcpp::SHT_REL or elfcpp::SHT_RELA.
+
+template<int sh_type, int size, bool big_endian>
+class Copy_relocs
+{
+ private:
+ typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reloc;
+
+ public:
+ Copy_relocs(unsigned int copy_reloc_type)
+ : copy_reloc_type_(copy_reloc_type), dynbss_(NULL), entries_()
+ { }
+
+ // This is called while scanning relocs if we see a relocation
+ // against a symbol which may force us to generate a COPY reloc.
+ // SYM is the symbol. OBJECT is the object whose relocs we are
+ // scanning. The relocation is being applied to section SHNDX in
+ // OBJECT. OUTPUT_SECTION is the output section where section SHNDX
+ // will wind up. REL is the reloc itself. The Output_data_reloc
+ // section is where the dynamic relocs are put.
+ void
+ copy_reloc(Symbol_table*, Layout*, Sized_symbol<size>* sym,
+ Sized_relobj<size, big_endian>* object,
+ unsigned int shndx, Output_section* output_section,
+ const Reloc& rel,
+ Output_data_reloc<sh_type, true, size, big_endian>*);
+
+ // Return whether there are any saved relocations.
+ bool
+ any_saved_relocs() const
+ { return !this->entries_.empty(); }
+
+ // Emit any saved relocations which turn out to be needed. This is
+ // called after all the relocs have been scanned.
+ void
+ emit(Output_data_reloc<sh_type, true, size, big_endian>*);
+
+ private:
+ typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
+ typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend;
+
+ // This POD class holds the relocations we are saving. We will emit
+ // these relocations if it turns out that the symbol does not
+ // require a COPY relocation.
+ class Copy_reloc_entry
+ {
+ public:
+ Copy_reloc_entry(Symbol* sym, unsigned int reloc_type,
+ Sized_relobj<size, big_endian>* relobj,
+ unsigned int shndx,
+ Output_section* output_section,
+ Address address, Addend addend)
+ : sym_(sym), reloc_type_(reloc_type), relobj_(relobj),
+ shndx_(shndx), output_section_(output_section),
+ address_(address), addend_(addend)
+ { }
+
+ // Emit this reloc if appropriate. This is called after we have
+ // scanned all the relocations, so we know whether we emitted a
+ // COPY relocation for SYM_.
+ void
+ emit(Output_data_reloc<sh_type, true, size, big_endian>*);
+
+ private:
+ Symbol* sym_;
+ unsigned int reloc_type_;
+ Sized_relobj<size, big_endian>* relobj_;
+ unsigned int shndx_;
+ Output_section* output_section_;
+ Address address_;
+ Addend addend_;
+ };
+
+ // A list of relocs to be saved.
+ typedef std::vector<Copy_reloc_entry> Copy_reloc_entries;
+
+ // Return whether we need a COPY reloc.
+ bool
+ need_copy_reloc(Sized_symbol<size>* gsym,
+ Sized_relobj<size, big_endian>* object,
+ unsigned int shndx) const;
+
+ // Emit a COPY reloc.
+ void
+ emit_copy_reloc(Symbol_table*, Layout*, Sized_symbol<size>*,
+ Output_data_reloc<sh_type, true, size, big_endian>*);
+
+ // Add a COPY reloc to the dynamic reloc section.
+ void
+ add_copy_reloc(Symbol*, section_size_type,
+ Output_data_reloc<sh_type, true, size, big_endian>*);
+
+ // Save a reloc against SYM for possible emission later.
+ void
+ save(Symbol*, Sized_relobj<size, big_endian>*, unsigned int shndx,
+ Output_section*, const Reloc& rel);
+
+ // The target specific relocation type of the COPY relocation.
+ const unsigned int copy_reloc_type_;
+ // The dynamic BSS data which goes into the .bss section. This is
+ // where variables which require COPY relocations are placed.
+ Output_data_space* dynbss_;
+ // The list of relocs we are saving.
+ Copy_reloc_entries entries_;
+};
+
+} // End namespace gold.
+
+#endif // !defined(GOLD_COPY_RELOCS_H)
projects / msp430-binutils.git / blobdiff