// 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 <iant@google.com>.
// This file is part of gold.
#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<int size, bool big_endian, typename Target_type, int sh_type,
typename Scan>
gold_assert(plocal_syms != NULL);
typename elfcpp::Sym<size, big_endian> 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
}
scan.local(options, symtab, layout, target, object, data_shndx,
- reloc, r_type, lsym);
+ output_section, reloc, r_type, lsym);
}
else
{
gsym = symtab->resolve_forwards(gsym);
scan.global(options, symtab, layout, target, object, data_shndx,
- reloc, r_type, gsym);
+ 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.
-// 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.
bool needs_special_offset_handling,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr view_address,
- off_t view_size)
+ section_size_type view_size)
{
typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
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);
- off_t offset = reloc.get_r_offset();
+ section_offset_type offset =
+ convert_to_section_size_type(reloc.get_r_offset());
if (needs_special_offset_handling)
{
{
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
{
psymval = &symval;
}
- if (!relocate.relocate(relinfo, target, i, reloc, r_type, sym, psymval,
- view + offset, view_address + offset, view_size))
+ if (!relocate.relocate(relinfo, target, output_section, i, reloc,
+ r_type, sym, psymval, view + offset,
+ view_address + offset, view_size))
continue;
- if (offset < 0 || offset >= view_size)
+ if (offset < 0 || static_cast<section_size_type>(offset) >= view_size)
{
gold_error_at_location(relinfo, i, offset,
_("reloc has bad offset %zu"),
if (sym != NULL
&& sym->is_undefined()
&& sym->binding() != elfcpp::STB_WEAK
- && !parameters->output_is_shared())
- gold_undefined_symbol(sym, relinfo, i, offset);
+ && !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)
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