URL
https://opencores.org/ocsvn/openrisc_2011-10-31/openrisc_2011-10-31/trunk
Subversion Repositories openrisc_2011-10-31
[/] [openrisc/] [trunk/] [gnu-src/] [binutils-2.20.1/] [gold/] [target-reloc.h] - Rev 410
Go to most recent revision | Compare with Previous | Blame | View Log
// target-reloc.h -- target specific relocation support -*- 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_TARGET_RELOC_H #define GOLD_TARGET_RELOC_H #include "elfcpp.h" #include "symtab.h" #include "object.h" #include "reloc.h" #include "reloc-types.h" namespace gold { // This function implements the generic part of reloc scanning. The // template parameter Scan must be a class type which provides two // functions: local() and global(). Those functions implement the // machine specific part of scanning. We do it this way to // avoidmaking a function call for each relocation, and to avoid // repeating the generic code for each target. template<int size, bool big_endian, typename Target_type, int sh_type, typename Scan> inline void scan_relocs( const General_options& options, Symbol_table* symtab, Layout* layout, Target_type* target, Sized_relobj<size, big_endian>* object, unsigned int data_shndx, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_count, const unsigned char* plocal_syms) { typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype; const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size; const int sym_size = elfcpp::Elf_sizes<size>::sym_size; Scan scan; for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size) { Reltype reloc(prelocs); if (needs_special_offset_handling && !output_section->is_input_address_mapped(object, data_shndx, reloc.get_r_offset())) continue; typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info(); unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info); unsigned int r_type = elfcpp::elf_r_type<size>(r_info); if (r_sym < local_count) { gold_assert(plocal_syms != NULL); typename elfcpp::Sym<size, big_endian> lsym(plocal_syms + r_sym * sym_size); unsigned int shndx = lsym.get_st_shndx(); bool is_ordinary; shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary); if (is_ordinary && shndx != elfcpp::SHN_UNDEF && !object->is_section_included(shndx)) { // RELOC is a relocation against a local symbol in a // section we are discarding. We can ignore this // relocation. It will eventually become a reloc // against the value zero. // // FIXME: We should issue a warning if this is an // allocated section; is this the best place to do it? // // FIXME: The old GNU linker would in some cases look // for the linkonce section which caused this section to // be discarded, and, if the other section was the same // size, change the reloc to refer to the other section. // That seems risky and weird to me, and I don't know of // any case where it is actually required. continue; } scan.local(options, symtab, layout, target, object, data_shndx, output_section, reloc, r_type, lsym); } else { Symbol* gsym = object->global_symbol(r_sym); gold_assert(gsym != NULL); if (gsym->is_forwarder()) gsym = symtab->resolve_forwards(gsym); scan.global(options, symtab, layout, target, object, data_shndx, output_section, reloc, r_type, gsym); } } } // Behavior for relocations to discarded comdat sections. enum Comdat_behavior { CB_UNDETERMINED, // Not yet determined -- need to look at section name. CB_PRETEND, // Attempt to map to the corresponding kept section. CB_IGNORE, // Ignore the relocation. CB_WARNING // Print a warning. }; // Decide what the linker should do for relocations that refer to discarded // comdat sections. This decision is based on the name of the section being // relocated. inline Comdat_behavior get_comdat_behavior(const char* name) { if (Layout::is_debug_info_section(name)) return CB_PRETEND; if (strcmp(name, ".eh_frame") == 0 || strcmp(name, ".gcc_except_table") == 0) return CB_IGNORE; return CB_WARNING; } // This function implements the generic part of relocation processing. // The template parameter Relocate must be a class type which provides // a single function, relocate(), which implements the machine // specific part of a relocation. // SIZE is the ELF size: 32 or 64. BIG_ENDIAN is the endianness of // the data. SH_TYPE is the section type: SHT_REL or SHT_RELA. // RELOCATE implements operator() to do a relocation. // PRELOCS points to the relocation data. RELOC_COUNT is the number // of relocs. OUTPUT_SECTION is the output section. // NEEDS_SPECIAL_OFFSET_HANDLING is true if input offsets need to be // mapped to output offsets. // VIEW is the section data, VIEW_ADDRESS is its memory address, and // VIEW_SIZE is the size. These refer to the input section, unless // NEEDS_SPECIAL_OFFSET_HANDLING is true, in which case they refer to // the output section. // RELOC_SYMBOL_CHANGES is used for -fsplit-stack support. If it is // not NULL, it is a vector indexed by relocation index. If that // entry is not NULL, it points to a global symbol which used as the // symbol for the relocation, ignoring the symbol index in the // relocation. template<int size, bool big_endian, typename Target_type, int sh_type, typename Relocate> inline void relocate_section( const Relocate_info<size, big_endian>* relinfo, Target_type* target, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, unsigned char* view, typename elfcpp::Elf_types<size>::Elf_Addr view_address, section_size_type view_size, const Reloc_symbol_changes* reloc_symbol_changes) { typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype; const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size; Relocate relocate; Sized_relobj<size, big_endian>* object = relinfo->object; unsigned int local_count = object->local_symbol_count(); Comdat_behavior comdat_behavior = CB_UNDETERMINED; for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size) { Reltype reloc(prelocs); section_offset_type offset = convert_to_section_size_type(reloc.get_r_offset()); if (needs_special_offset_handling) { offset = output_section->output_offset(relinfo->object, relinfo->data_shndx, offset); if (offset == -1) continue; } typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info(); unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info); unsigned int r_type = elfcpp::elf_r_type<size>(r_info); const Sized_symbol<size>* sym; Symbol_value<size> symval; const Symbol_value<size> *psymval; if (r_sym < local_count && (reloc_symbol_changes == NULL || (*reloc_symbol_changes)[i] == NULL)) { sym = NULL; psymval = object->local_symbol(r_sym); // If the local symbol belongs to a section we are discarding, // and that section is a debug section, try to find the // corresponding kept section and map this symbol to its // counterpart in the kept section. The symbol must not // correspond to a section we are folding. bool is_ordinary; unsigned int shndx = psymval->input_shndx(&is_ordinary); if (is_ordinary && shndx != elfcpp::SHN_UNDEF && !object->is_section_included(shndx) && !(relinfo->symtab->is_section_folded(object, shndx))) { if (comdat_behavior == CB_UNDETERMINED) { std::string name = object->section_name(relinfo->data_shndx); comdat_behavior = get_comdat_behavior(name.c_str()); } if (comdat_behavior == CB_PRETEND) { bool found; typename elfcpp::Elf_types<size>::Elf_Addr value = object->map_to_kept_section(shndx, &found); if (found) symval.set_output_value(value + psymval->input_value()); else symval.set_output_value(0); } else { if (comdat_behavior == CB_WARNING) gold_warning_at_location(relinfo, i, offset, _("relocation refers to discarded " "comdat section")); symval.set_output_value(0); } symval.set_no_output_symtab_entry(); psymval = &symval; } } else { const Symbol* gsym; if (reloc_symbol_changes != NULL && (*reloc_symbol_changes)[i] != NULL) gsym = (*reloc_symbol_changes)[i]; else { gsym = object->global_symbol(r_sym); gold_assert(gsym != NULL); if (gsym->is_forwarder()) gsym = relinfo->symtab->resolve_forwards(gsym); } sym = static_cast<const Sized_symbol<size>*>(gsym); if (sym->has_symtab_index()) symval.set_output_symtab_index(sym->symtab_index()); else symval.set_no_output_symtab_entry(); symval.set_output_value(sym->value()); psymval = &symval; } if (!relocate.relocate(relinfo, target, output_section, i, reloc, r_type, sym, psymval, view + offset, view_address + offset, view_size)) continue; if (offset < 0 || static_cast<section_size_type>(offset) >= view_size) { gold_error_at_location(relinfo, i, offset, _("reloc has bad offset %zu"), static_cast<size_t>(offset)); continue; } if (sym != NULL && sym->is_undefined() && sym->binding() != elfcpp::STB_WEAK && !target->is_defined_by_abi(sym) && (!parameters->options().shared() // -shared || parameters->options().defs())) // -z defs gold_undefined_symbol_at_location(sym, relinfo, i, offset); if (sym != NULL && sym->has_warning()) relinfo->symtab->issue_warning(sym, relinfo, i, offset); } } // This class may be used as a typical class for the // Scan_relocatable_reloc parameter to scan_relocatable_relocs. The // template parameter Classify_reloc must be a class type which // provides a function get_size_for_reloc which returns the number of // bytes to which a reloc applies. This class is intended to capture // the most typical target behaviour, while still permitting targets // to define their own independent class for Scan_relocatable_reloc. template<int sh_type, typename Classify_reloc> class Default_scan_relocatable_relocs { public: // Return the strategy to use for a local symbol which is not a // section symbol, given the relocation type. inline Relocatable_relocs::Reloc_strategy local_non_section_strategy(unsigned int r_type, Relobj*, unsigned int r_sym) { // We assume that relocation type 0 is NONE. Targets which are // different must override. if (r_type == 0 && r_sym == 0) return Relocatable_relocs::RELOC_DISCARD; return Relocatable_relocs::RELOC_COPY; } // Return the strategy to use for a local symbol which is a section // symbol, given the relocation type. inline Relocatable_relocs::Reloc_strategy local_section_strategy(unsigned int r_type, Relobj* object) { if (sh_type == elfcpp::SHT_RELA) return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA; else { Classify_reloc classify; switch (classify.get_size_for_reloc(r_type, object)) { case 0: return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0; case 1: return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1; case 2: return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2; case 4: return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4; case 8: return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8; default: gold_unreachable(); } } } // Return the strategy to use for a global symbol, given the // relocation type, the object, and the symbol index. inline Relocatable_relocs::Reloc_strategy global_strategy(unsigned int, Relobj*, unsigned int) { return Relocatable_relocs::RELOC_COPY; } }; // Scan relocs during a relocatable link. This is a default // definition which should work for most targets. // Scan_relocatable_reloc must name a class type which provides three // functions which return a Relocatable_relocs::Reloc_strategy code: // global_strategy, local_non_section_strategy, and // local_section_strategy. Most targets should be able to use // Default_scan_relocatable_relocs as this class. template<int size, bool big_endian, int sh_type, typename Scan_relocatable_reloc> void scan_relocatable_relocs( const General_options&, Symbol_table*, Layout*, Sized_relobj<size, big_endian>* object, unsigned int data_shndx, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, bool needs_special_offset_handling, size_t local_symbol_count, const unsigned char* plocal_syms, Relocatable_relocs* rr) { typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype; const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size; const int sym_size = elfcpp::Elf_sizes<size>::sym_size; Scan_relocatable_reloc scan; for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size) { Reltype reloc(prelocs); Relocatable_relocs::Reloc_strategy strategy; if (needs_special_offset_handling && !output_section->is_input_address_mapped(object, data_shndx, reloc.get_r_offset())) strategy = Relocatable_relocs::RELOC_DISCARD; else { typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info(); const unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info); const unsigned int r_type = elfcpp::elf_r_type<size>(r_info); if (r_sym >= local_symbol_count) strategy = scan.global_strategy(r_type, object, r_sym); else { gold_assert(plocal_syms != NULL); typename elfcpp::Sym<size, big_endian> lsym(plocal_syms + r_sym * sym_size); unsigned int shndx = lsym.get_st_shndx(); bool is_ordinary; shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary); if (is_ordinary && shndx != elfcpp::SHN_UNDEF && !object->is_section_included(shndx)) { // RELOC is a relocation against a local symbol // defined in a section we are discarding. Discard // the reloc. FIXME: Should we issue a warning? strategy = Relocatable_relocs::RELOC_DISCARD; } else if (lsym.get_st_type() != elfcpp::STT_SECTION) strategy = scan.local_non_section_strategy(r_type, object, r_sym); else { strategy = scan.local_section_strategy(r_type, object); if (strategy != Relocatable_relocs::RELOC_DISCARD) object->output_section(shndx)->set_needs_symtab_index(); } } } rr->set_next_reloc_strategy(strategy); } } // Relocate relocs during a relocatable link. This is a default // definition which should work for most targets. template<int size, bool big_endian, int sh_type> void relocate_for_relocatable( const Relocate_info<size, big_endian>* relinfo, const unsigned char* prelocs, size_t reloc_count, Output_section* output_section, typename elfcpp::Elf_types<size>::Elf_Addr offset_in_output_section, const Relocatable_relocs* rr, unsigned char* view, typename elfcpp::Elf_types<size>::Elf_Addr view_address, section_size_type, unsigned char* reloc_view, section_size_type reloc_view_size) { typedef typename elfcpp::Elf_types<size>::Elf_Addr Address; typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype; typedef typename Reloc_types<sh_type, size, big_endian>::Reloc_write Reltype_write; const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size; const Address invalid_address = static_cast<Address>(0) - 1; Sized_relobj<size, big_endian>* const object = relinfo->object; const unsigned int local_count = object->local_symbol_count(); unsigned char* pwrite = reloc_view; for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size) { Relocatable_relocs::Reloc_strategy strategy = rr->strategy(i); if (strategy == Relocatable_relocs::RELOC_DISCARD) continue; Reltype reloc(prelocs); Reltype_write reloc_write(pwrite); typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info(); const unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info); const unsigned int r_type = elfcpp::elf_r_type<size>(r_info); // Get the new symbol index. unsigned int new_symndx; if (r_sym < local_count) { switch (strategy) { case Relocatable_relocs::RELOC_COPY: new_symndx = object->symtab_index(r_sym); gold_assert(new_symndx != -1U); break; case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA: case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0: case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1: case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2: case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4: case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8: { // We are adjusting a section symbol. We need to find // the symbol table index of the section symbol for // the output section corresponding to input section // in which this symbol is defined. gold_assert(r_sym < local_count); bool is_ordinary; unsigned int shndx = object->local_symbol_input_shndx(r_sym, &is_ordinary); gold_assert(is_ordinary); Output_section* os = object->output_section(shndx); gold_assert(os != NULL); gold_assert(os->needs_symtab_index()); new_symndx = os->symtab_index(); } break; default: gold_unreachable(); } } else { const Symbol* gsym = object->global_symbol(r_sym); gold_assert(gsym != NULL); if (gsym->is_forwarder()) gsym = relinfo->symtab->resolve_forwards(gsym); gold_assert(gsym->has_symtab_index()); new_symndx = gsym->symtab_index(); } // Get the new offset--the location in the output section where // this relocation should be applied. Address offset = reloc.get_r_offset(); Address new_offset; if (offset_in_output_section != invalid_address) new_offset = offset + offset_in_output_section; else { section_offset_type sot_offset = convert_types<section_offset_type, Address>(offset); section_offset_type new_sot_offset = output_section->output_offset(object, relinfo->data_shndx, sot_offset); gold_assert(new_sot_offset != -1); new_offset = new_sot_offset; } // In an object file, r_offset is an offset within the section. // In an executable or dynamic object, generated by // --emit-relocs, r_offset is an absolute address. if (!parameters->options().relocatable()) { new_offset += view_address; if (offset_in_output_section != invalid_address) new_offset -= offset_in_output_section; } reloc_write.put_r_offset(new_offset); reloc_write.put_r_info(elfcpp::elf_r_info<size>(new_symndx, r_type)); // Handle the reloc addend based on the strategy. if (strategy == Relocatable_relocs::RELOC_COPY) { if (sh_type == elfcpp::SHT_RELA) Reloc_types<sh_type, size, big_endian>:: copy_reloc_addend(&reloc_write, &reloc); } else { // The relocation uses a section symbol in the input file. // We are adjusting it to use a section symbol in the output // file. The input section symbol refers to some address in // the input section. We need the relocation in the output // file to refer to that same address. This adjustment to // the addend is the same calculation we use for a simple // absolute relocation for the input section symbol. const Symbol_value<size>* psymval = object->local_symbol(r_sym); unsigned char* padd = view + offset; switch (strategy) { case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA: { typename elfcpp::Elf_types<size>::Elf_Swxword addend; addend = Reloc_types<sh_type, size, big_endian>:: get_reloc_addend(&reloc); addend = psymval->value(object, addend); Reloc_types<sh_type, size, big_endian>:: set_reloc_addend(&reloc_write, addend); } break; case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0: break; case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1: Relocate_functions<size, big_endian>::rel8(padd, object, psymval); break; case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2: Relocate_functions<size, big_endian>::rel16(padd, object, psymval); break; case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4: Relocate_functions<size, big_endian>::rel32(padd, object, psymval); break; case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8: Relocate_functions<size, big_endian>::rel64(padd, object, psymval); break; default: gold_unreachable(); } } pwrite += reloc_size; } gold_assert(static_cast<section_size_type>(pwrite - reloc_view) == reloc_view_size); } } // End namespace gold. #endif // !defined(GOLD_TARGET_RELOC_H)
Go to most recent revision | Compare with Previous | Blame | View Log