// target-reloc.h -- target specific relocation support -*- C++ -*-
-// Copyright 2006, 2007 Free Software Foundation, Inc.
+// Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013
+// 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 "object.h"
#include "reloc.h"
#include "reloc-types.h"
// 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
+// avoid making 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,
+ Sized_relobj_file<size, big_endian>* object,
unsigned int data_shndx,
const unsigned char* prelocs,
size_t reloc_count,
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
- && shndx != elfcpp::SHN_UNDEF
- && !object->is_section_included(lsym.get_st_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);
+ unsigned int shndx = lsym.get_st_shndx();
+ bool is_ordinary;
+ shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
+ // If RELOC is a relocation against a local symbol in a
+ // section we are discarding then we can ignore it. 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.
+ bool is_discarded = (is_ordinary
+ && shndx != elfcpp::SHN_UNDEF
+ && !object->is_section_included(shndx)
+ && !symtab->is_section_folded(object, shndx));
+ scan.local(symtab, layout, target, object, data_shndx,
+ output_section, reloc, r_type, lsym, is_discarded);
}
else
{
if (gsym->is_forwarder())
gsym = symtab->resolve_forwards(gsym);
- scan.global(options, symtab, layout, target, object, data_shndx,
+ scan.global(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.
+};
+
+class Default_comdat_behavior
+{
+ public:
+ // 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(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;
+ }
+};
+
+// Give an error for a symbol with non-default visibility which is not
+// defined locally.
+
+inline void
+visibility_error(const Symbol* sym)
+{
+ const char* v;
+ switch (sym->visibility())
+ {
+ case elfcpp::STV_INTERNAL:
+ v = _("internal");
+ break;
+ case elfcpp::STV_HIDDEN:
+ v = _("hidden");
+ break;
+ case elfcpp::STV_PROTECTED:
+ v = _("protected");
+ break;
+ default:
+ gold_unreachable();
+ }
+ gold_error(_("%s symbol '%s' is not defined locally"),
+ v, sym->name());
+}
+
+// Return true if we are should issue an error saying that SYM is an
+// undefined symbol. This is called if there is a relocation against
+// SYM.
+
+inline bool
+issue_undefined_symbol_error(const Symbol* sym)
+{
+ // We only report global symbols.
+ if (sym == NULL)
+ return false;
+
+ // We only report undefined symbols.
+ if (!sym->is_undefined() && !sym->is_placeholder())
+ return false;
+
+ // We don't report weak symbols.
+ if (sym->binding() == elfcpp::STB_WEAK)
+ return false;
+
+ // We don't report symbols defined in discarded sections.
+ if (sym->is_defined_in_discarded_section())
+ return false;
+
+ // If the target defines this symbol, don't report it here.
+ if (parameters->target().is_defined_by_abi(sym))
+ return false;
+
+ // See if we've been told to ignore whether this symbol is
+ // undefined.
+ const char* const u = parameters->options().unresolved_symbols();
+ if (u != NULL)
+ {
+ if (strcmp(u, "ignore-all") == 0)
+ return false;
+ if (strcmp(u, "report-all") == 0)
+ return true;
+ if (strcmp(u, "ignore-in-object-files") == 0 && !sym->in_dyn())
+ return false;
+ if (strcmp(u, "ignore-in-shared-libs") == 0 && !sym->in_reg())
+ return false;
+ }
+
+ // When creating a shared library, only report unresolved symbols if
+ // -z defs was used.
+ if (parameters->options().shared() && !parameters->options().defs())
+ return false;
+
+ // Otherwise issue a warning.
+ return true;
+}
+
// 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.
+// The template parameter Relocate_comdat_behavior is a class type
+// which provides a single function, get(), which determines what the
+// linker should do for relocations that refer to discarded comdat
+// sections.
+
// 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.
// 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>
+ typename Relocate,
+ typename Relocate_comdat_behavior>
inline void
relocate_section(
const Relocate_info<size, big_endian>* relinfo,
bool needs_special_offset_handling,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr view_address,
- section_size_type view_size)
+ 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;
+ Relocate_comdat_behavior relocate_comdat_behavior;
- Sized_relobj<size, big_endian>* object = relinfo->object;
+ Sized_relobj_file<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);
Symbol_value<size> symval;
const Symbol_value<size> *psymval;
- if (r_sym < local_count)
+ bool is_defined_in_discarded_section;
+ unsigned int shndx;
+ 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;
+ shndx = psymval->input_shndx(&is_ordinary);
+ is_defined_in_discarded_section =
+ (is_ordinary
+ && shndx != elfcpp::SHN_UNDEF
+ && !object->is_section_included(shndx)
+ && !relinfo->symtab->is_section_folded(object, shndx));
}
else
{
- const Symbol* gsym = object->global_symbol(r_sym);
- gold_assert(gsym != NULL);
- if (gsym->is_forwarder())
- gsym = relinfo->symtab->resolve_forwards(gsym);
+ 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())
+ if (sym->has_symtab_index() && sym->symtab_index() != -1U)
symval.set_output_symtab_index(sym->symtab_index());
else
symval.set_no_output_symtab_entry();
symval.set_output_value(sym->value());
+ if (gsym->type() == elfcpp::STT_TLS)
+ symval.set_is_tls_symbol();
+ else if (gsym->type() == elfcpp::STT_GNU_IFUNC)
+ symval.set_is_ifunc_symbol();
psymval = &symval;
+
+ is_defined_in_discarded_section =
+ (gsym->is_defined_in_discarded_section()
+ && gsym->is_undefined());
+ shndx = 0;
}
- if (!relocate.relocate(relinfo, target, i, reloc, r_type, sym, psymval,
- view + offset, view_address + offset, view_size))
- continue;
+ Symbol_value<size> symval2;
+ if (is_defined_in_discarded_section)
+ {
+ if (comdat_behavior == CB_UNDETERMINED)
+ {
+ std::string name = object->section_name(relinfo->data_shndx);
+ comdat_behavior = relocate_comdat_behavior.get(name.c_str());
+ }
+ if (comdat_behavior == CB_PRETEND)
+ {
+ // FIXME: This case does not work for global symbols.
+ // We have no place to store the original section index.
+ // Fortunately this does not matter for comdat sections,
+ // only for sections explicitly discarded by a linker
+ // script.
+ bool found;
+ typename elfcpp::Elf_types<size>::Elf_Addr value =
+ object->map_to_kept_section(shndx, &found);
+ if (found)
+ symval2.set_output_value(value + psymval->input_value());
+ else
+ symval2.set_output_value(0);
+ }
+ else
+ {
+ if (comdat_behavior == CB_WARNING)
+ gold_warning_at_location(relinfo, i, offset,
+ _("relocation refers to discarded "
+ "section"));
+ symval2.set_output_value(0);
+ }
+ symval2.set_no_output_symtab_entry();
+ psymval = &symval2;
+ }
+ // If OFFSET is out of range, still let the target decide to
+ // ignore the relocation. Pass in NULL as the VIEW argument so
+ // that it can return quickly without trashing an invalid memory
+ // address.
+ unsigned char *v = view + offset;
if (offset < 0 || static_cast<section_size_type>(offset) >= view_size)
+ v = NULL;
+
+ if (!relocate.relocate(relinfo, target, output_section, i, reloc,
+ r_type, sym, psymval, v, view_address + offset,
+ view_size))
+ continue;
+
+ if (v == NULL)
{
gold_error_at_location(relinfo, i, offset,
_("reloc has bad offset %zu"),
continue;
}
- if (sym != NULL
- && sym->is_undefined()
- && sym->binding() != elfcpp::STB_WEAK
- && !parameters->options().shared())
- gold_undefined_symbol(sym, relinfo, i, offset);
+ if (issue_undefined_symbol_error(sym))
+ {
+ gold_undefined_symbol_at_location(sym, relinfo, i, offset);
+ if (sym->is_cxx_vtable())
+ gold_info(_("%s: the vtable symbol may be undefined because "
+ "the class is missing its key function"),
+ program_name);
+ }
+ else if (sym != NULL
+ && sym->visibility() != elfcpp::STV_DEFAULT
+ && (sym->is_undefined() || sym->is_from_dynobj()))
+ visibility_error(sym);
if (sym != NULL && sym->has_warning())
relinfo->symtab->issue_warning(sym, relinfo, i, offset);
}
}
+// Apply an incremental relocation.
+
+template<int size, bool big_endian, typename Target_type,
+ typename Relocate>
+void
+apply_relocation(const Relocate_info<size, big_endian>* relinfo,
+ Target_type* target,
+ typename elfcpp::Elf_types<size>::Elf_Addr r_offset,
+ unsigned int r_type,
+ typename elfcpp::Elf_types<size>::Elf_Swxword r_addend,
+ const Symbol* gsym,
+ unsigned char* view,
+ typename elfcpp::Elf_types<size>::Elf_Addr address,
+ section_size_type view_size)
+{
+ // Construct the ELF relocation in a temporary buffer.
+ const int reloc_size = elfcpp::Elf_sizes<size>::rela_size;
+ unsigned char relbuf[reloc_size];
+ elfcpp::Rela<size, big_endian> rel(relbuf);
+ elfcpp::Rela_write<size, big_endian> orel(relbuf);
+ orel.put_r_offset(r_offset);
+ orel.put_r_info(elfcpp::elf_r_info<size>(0, r_type));
+ orel.put_r_addend(r_addend);
+
+ // Setup a Symbol_value for the global symbol.
+ const Sized_symbol<size>* sym = static_cast<const Sized_symbol<size>*>(gsym);
+ Symbol_value<size> symval;
+ gold_assert(sym->has_symtab_index() && sym->symtab_index() != -1U);
+ symval.set_output_symtab_index(sym->symtab_index());
+ symval.set_output_value(sym->value());
+ if (gsym->type() == elfcpp::STT_TLS)
+ symval.set_is_tls_symbol();
+ else if (gsym->type() == elfcpp::STT_GNU_IFUNC)
+ symval.set_is_ifunc_symbol();
+
+ Relocate relocate;
+ relocate.relocate(relinfo, target, NULL, -1U, rel, r_type, sym, &symval,
+ view + r_offset, address + r_offset, view_size);
+}
+
// 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
// 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; }
+ 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.
typename Scan_relocatable_reloc>
void
scan_relocatable_relocs(
- const General_options&,
Symbol_table*,
Layout*,
- Sized_relobj<size, big_endian>* object,
+ Sized_relobj_file<size, big_endian>* object,
unsigned int data_shndx,
const unsigned char* prelocs,
size_t reloc_count,
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
// defined in a section we are discarding. Discard
strategy = Relocatable_relocs::RELOC_DISCARD;
}
else if (lsym.get_st_type() != elfcpp::STT_SECTION)
- strategy = scan.local_non_section_strategy(r_type, object);
+ 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)
- {
- section_offset_type dummy;
- Output_section* os = object->output_section(shndx,
- &dummy);
- os->set_needs_symtab_index();
- }
+ object->output_section(shndx)->set_needs_symtab_index();
}
+
+ if (strategy == Relocatable_relocs::RELOC_COPY)
+ object->set_must_have_output_symtab_entry(r_sym);
}
}
}
}
-// Relocate relocs during a relocatable link. This is a default
-// definition which should work for most targets.
+// Relocate relocs. Called for a relocatable link, and for --emit-relocs.
+// This is a default definition which should work for most targets.
template<int size, bool big_endian, int sh_type>
void
-relocate_for_relocatable(
+relocate_relocs(
const Relocate_info<size, big_endian>* relinfo,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
- off_t offset_in_output_section,
+ typename elfcpp::Elf_types<size>::Elf_Off offset_in_output_section,
const Relocatable_relocs* rr,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr view_address,
- section_size_type,
+ section_size_type view_size,
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;
+ Sized_relobj_file<size, big_endian>* const object = relinfo->object;
const unsigned int local_count = object->local_symbol_count();
unsigned char* pwrite = reloc_view;
if (strategy == Relocatable_relocs::RELOC_DISCARD)
continue;
+ if (strategy == Relocatable_relocs::RELOC_SPECIAL)
+ {
+ // Target wants to handle this relocation.
+ Sized_target<size, big_endian>* target =
+ parameters->sized_target<size, big_endian>();
+ target->relocate_special_relocatable(relinfo, sh_type, prelocs,
+ i, output_section,
+ offset_in_output_section,
+ view, view_address,
+ view_size, pwrite);
+ pwrite += reloc_size;
+ continue;
+ }
Reltype reloc(prelocs);
Reltype_write reloc_write(pwrite);
switch (strategy)
{
case Relocatable_relocs::RELOC_COPY:
- new_symndx = object->symtab_index(r_sym);
- gold_assert(new_symndx != -1U);
+ if (r_sym == 0)
+ new_symndx = 0;
+ else
+ {
+ 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_2:
case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4:
case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8:
+ case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4_UNALIGNED:
{
// 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);
- unsigned int shndx = object->local_symbol_input_shndx(r_sym);
- section_offset_type dummy;
- Output_section* os = object->output_section(shndx, &dummy);
+ 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();
// 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)
+ Address offset = reloc.get_r_offset();
+ Address new_offset;
+ if (offset_in_output_section != invalid_address)
new_offset = offset + offset_in_output_section;
else
{
- new_offset = output_section->output_offset(object,
- relinfo->data_shndx,
- offset);
- gold_assert(new_offset != -1);
+ 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;
+ {
+ 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));
psymval);
break;
+ case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4_UNALIGNED:
+ Relocate_functions<size, big_endian>::rel32_unaligned(padd,
+ object,
+ psymval);
+ break;
+
default:
gold_unreachable();
}