X-Git-Url: http://drtracing.org/?a=blobdiff_plain;f=gold%2Ftarget-reloc.h;h=e1c3cc37b69892120bc26935a820919dadc9d922;hb=e94cf1277329c4eaba3b398b446e693550463c77;hp=771869149caaac6a35973edcfb822cd24555a673;hpb=fe8718a4637d92b3cd991a8f1a22d6d0a09bc6dd;p=deliverable%2Fbinutils-gdb.git diff --git a/gold/target-reloc.h b/gold/target-reloc.h index 771869149c..e1c3cc37b6 100644 --- a/gold/target-reloc.h +++ b/gold/target-reloc.h @@ -1,6 +1,6 @@ // target-reloc.h -- target specific relocation support -*- C++ -*- -// Copyright 2006, 2007 Free Software Foundation, Inc. +// Copyright 2006, 2007, 2008 Free Software Foundation, Inc. // Written by Ian Lance Taylor . // This file is part of gold. @@ -25,16 +25,18 @@ #include "elfcpp.h" #include "symtab.h" +#include "reloc.h" #include "reloc-types.h" namespace gold { -// This function implements the generic part of reloc scanning. This -// is an inline function which takes a class whose member functions -// local() and global() 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. +// 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 @@ -76,10 +78,12 @@ scan_relocs( gold_assert(plocal_syms != NULL); typename elfcpp::Sym lsym(plocal_syms + r_sym * sym_size); - const unsigned int shndx = lsym.get_st_shndx(); - if (shndx < elfcpp::SHN_LORESERVE + 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(lsym.get_st_shndx())) + && !object->is_section_included(shndx)) { // RELOC is a relocation against a local symbol in a // section we are discarding. We can ignore this @@ -115,12 +119,35 @@ scan_relocs( } } +// 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. -// This is an inline function which take a class whose relocate() -// implements the machine specific part of relocation. We do it this -// way to avoid making a function call for each relocation, and to -// avoid repeating the generic relocation handling code for each -// target. +// 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. @@ -157,6 +184,8 @@ relocate_section( Sized_relobj* 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); @@ -185,6 +214,44 @@ relocate_section( { 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. + bool is_ordinary; + unsigned int shndx = psymval->input_shndx(&is_ordinary); + if (is_ordinary + && shndx != elfcpp::SHN_UNDEF + && !object->is_section_included(shndx)) + { + if (comdat_behavior == CB_UNDETERMINED) + { + const char* name = + object->section_name(relinfo->data_shndx).c_str(); + comdat_behavior = get_comdat_behavior(name); + } + if (comdat_behavior == CB_PRETEND) + { + bool found; + typename elfcpp::Elf_types::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 { @@ -217,7 +284,8 @@ relocate_section( if (sym != NULL && sym->is_undefined() && sym->binding() != elfcpp::STB_WEAK - && !parameters->output_is_shared()) + && (!parameters->options().shared() // -shared + || parameters->options().defs())) // -z defs gold_undefined_symbol(sym, relinfo, i, offset); if (sym != NULL && sym->has_warning()) @@ -225,6 +293,331 @@ relocate_section( } } +// 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 +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, Relobj*) + { 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 +void +scan_relocatable_relocs( + const General_options&, + Symbol_table*, + Layout*, + Sized_relobj* 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::Reloc Reltype; + const int reloc_size = Reloc_types::reloc_size; + const int sym_size = elfcpp::Elf_sizes::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::Elf_WXword r_info = + reloc.get_r_info(); + const unsigned int r_sym = elfcpp::elf_r_sym(r_info); + const unsigned int r_type = elfcpp::elf_r_type(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 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); + else + { + strategy = scan.local_section_strategy(r_type, object); + if (strategy != Relocatable_relocs::RELOC_DISCARD) + { + section_offset_type dummy; + Output_section* os = object->output_section(shndx, + &dummy); + os->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 +void +relocate_for_relocatable( + const Relocate_info* relinfo, + const unsigned char* prelocs, + size_t reloc_count, + Output_section* output_section, + off_t offset_in_output_section, + const Relocatable_relocs* rr, + unsigned char* view, + typename elfcpp::Elf_types::Elf_Addr view_address, + section_size_type, + unsigned char* reloc_view, + section_size_type reloc_view_size) +{ + typedef typename Reloc_types::Reloc Reltype; + typedef typename Reloc_types::Reloc_write + Reltype_write; + const int reloc_size = Reloc_types::reloc_size; + + Sized_relobj* 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::Elf_WXword r_info = reloc.get_r_info(); + const unsigned int r_sym = elfcpp::elf_r_sym(r_info); + const unsigned int r_type = elfcpp::elf_r_type(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); + section_offset_type dummy; + Output_section* os = object->output_section(shndx, &dummy); + 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. + + off_t offset = reloc.get_r_offset(); + off_t new_offset; + if (offset_in_output_section != -1) + new_offset = offset + offset_in_output_section; + else + { + new_offset = output_section->output_offset(object, + relinfo->data_shndx, + offset); + gold_assert(new_offset != -1); + } + + // 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; + + reloc_write.put_r_offset(new_offset); + reloc_write.put_r_info(elfcpp::elf_r_info(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:: + 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* 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::Elf_Swxword addend; + addend = Reloc_types:: + get_reloc_addend(&reloc); + addend = psymval->value(object, addend); + Reloc_types:: + 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::rel8(padd, object, + psymval); + break; + + case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2: + Relocate_functions::rel16(padd, object, + psymval); + break; + + case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4: + Relocate_functions::rel32(padd, object, + psymval); + break; + + case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8: + Relocate_functions::rel64(padd, object, + psymval); + break; + + default: + gold_unreachable(); + } + } + + pwrite += reloc_size; + } + + gold_assert(static_cast(pwrite - reloc_view) + == reloc_view_size); +} + } // End namespace gold. #endif // !defined(GOLD_TARGET_RELOC_H)