// copy-relocs.cc -- handle COPY relocations for gold. // Copyright 2006, 2007, 2008, 2009, 2010 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, 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>* 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, Sized_relobj<size, big_endian>* object, unsigned int shndx) const { if (!parameters->options().copyreloc()) return false; 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) { // We should not be here if -z nocopyreloc is given. gold_assert(parameters->options().copyreloc()); 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()); bool is_ordinary; unsigned int shndx = sym->shndx(&is_ordinary); gold_assert(is_ordinary); typename elfcpp::Elf_types<size>::Elf_WXword addralign = sym->object()->section_addralign(shndx); typename Sized_symbol<size>::Value_type value = sym->value(); while ((value & (addralign - 1)) != 0) addralign >>= 1; // Mark the dynamic object as needed for the --as-needed option. sym->object()->set_is_needed(); if (this->dynbss_ == NULL) { this->dynbss_ = new Output_data_space(addralign, "** dynbss"); layout->add_output_section_data(".bss", elfcpp::SHT_NOBITS, elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, this->dynbss_, false, false, false, false); } 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, Sized_relobj<size, big_endian>* 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.