unsigned int r_sym_;
// If r_sym_ is invalid index. This points to a global symbol.
// Otherwise, this points a relobj. We used the unsized and target
- // independent Symbol and Relobj classes instead of Arm_symbol and
+ // independent Symbol and Relobj classes instead of Sized_symbol<32> and
// Arm_relobj. This is done to avoid making the stub class a template
// as most of the stub machinery is endianity-neutral. However, it
// may require a bit of casting done by users of this class.
got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
copy_relocs_(elfcpp::R_ARM_COPY), dynbss_(NULL), stub_tables_(),
stub_factory_(Stub_factory::get_instance()),
- may_use_blx_(true), should_force_pic_veneer_(false)
+ may_use_blx_(true), should_force_pic_veneer_(false),
+ arm_input_section_map_()
{ }
// Whether we can use BLX.
Stub_table<big_endian>*
new_stub_table(Arm_input_section<big_endian>*);
+ // Scan a section for stub generation.
+ void
+ scan_section_for_stubs(const Relocate_info<32, big_endian>*, unsigned int,
+ const unsigned char*, size_t, Output_section*,
+ bool, const unsigned char*, Arm_address,
+ section_size_type);
+
// Get the default ARM target.
static const Target_arm<big_endian>&
default_target()
reloc_uses_thumb_bit(unsigned int r_type);
protected:
+ // Make an ELF object.
+ Object*
+ do_make_elf_object(const std::string&, Input_file*, off_t,
+ const elfcpp::Ehdr<32, big_endian>& ehdr);
+
+ Object*
+ do_make_elf_object(const std::string&, Input_file*, off_t,
+ const elfcpp::Ehdr<32, !big_endian>&)
+ { gold_unreachable(); }
+
+ Object*
+ do_make_elf_object(const std::string&, Input_file*, off_t,
+ const elfcpp::Ehdr<64, false>&)
+ { gold_unreachable(); }
+
+ Object*
+ do_make_elf_object(const std::string&, Input_file*, off_t,
+ const elfcpp::Ehdr<64, true>&)
+ { gold_unreachable(); }
+
+ // Make an output section.
+ Output_section*
+ do_make_output_section(const char* name, elfcpp::Elf_Word type,
+ elfcpp::Elf_Xword flags)
+ { return new Arm_output_section<big_endian>(name, type, flags); }
+
void
do_adjust_elf_header(unsigned char* view, int len) const;
+ // We only need to generate stubs, and hence perform relaxation if we are
+ // not doing relocatable linking.
+ bool
+ do_may_relax() const
+ { return !parameters->options().relocatable(); }
+
+ bool
+ do_relax(int, const Input_objects*, Symbol_table*, Layout*);
+
private:
// The class which scans relocations.
class Scan
void
merge_processor_specific_flags(const std::string&, elfcpp::Elf_Word);
- Object*
- do_make_elf_object(const std::string&, Input_file*, off_t,
- const elfcpp::Ehdr<32, big_endian>& ehdr);
+ //
+ // Methods to support stub-generations.
+ //
- Object*
- do_make_elf_object(const std::string&, Input_file*, off_t,
- const elfcpp::Ehdr<32, !big_endian>&)
- { gold_unreachable(); }
+ // Group input sections for stub generation.
+ void
+ group_sections(Layout*, section_size_type, bool);
- Object*
- do_make_elf_object(const std::string&, Input_file*, off_t,
- const elfcpp::Ehdr<64, false>&)
- { gold_unreachable(); }
+ // Scan a relocation for stub generation.
+ void
+ scan_reloc_for_stub(const Relocate_info<32, big_endian>*, unsigned int,
+ const Sized_symbol<32>*, unsigned int,
+ const Symbol_value<32>*,
+ elfcpp::Elf_types<32>::Elf_Swxword, Arm_address);
- Object*
- do_make_elf_object(const std::string&, Input_file*, off_t,
- const elfcpp::Ehdr<64, true>&)
- { gold_unreachable(); }
+ // Scan a relocation section for stub.
+ template<int sh_type>
+ void
+ scan_reloc_section_for_stubs(
+ const Relocate_info<32, big_endian>* relinfo,
+ const unsigned char* prelocs,
+ size_t reloc_count,
+ Output_section* output_section,
+ bool needs_special_offset_handling,
+ const unsigned char* view,
+ elfcpp::Elf_types<32>::Elf_Addr view_address,
+ section_size_type);
// Information about this specific target which we pass to the
// general Target structure.
bool may_use_blx_;
// Whether we force PIC branch veneers.
bool should_force_pic_veneer_;
+ // Map for locating Arm_input_sections.
+ Arm_input_section_map arm_input_section_map_;
};
template<bool big_endian>
return stub_table;
}
+// Scan a relocation for stub generation.
+
+template<bool big_endian>
+void
+Target_arm<big_endian>::scan_reloc_for_stub(
+ const Relocate_info<32, big_endian>* relinfo,
+ unsigned int r_type,
+ const Sized_symbol<32>* gsym,
+ unsigned int r_sym,
+ const Symbol_value<32>* psymval,
+ elfcpp::Elf_types<32>::Elf_Swxword addend,
+ Arm_address address)
+{
+ typedef typename Target_arm<big_endian>::Relocate Relocate;
+
+ const Arm_relobj<big_endian>* arm_relobj =
+ Arm_relobj<big_endian>::as_arm_relobj(relinfo->object);
+
+ bool target_is_thumb;
+ Symbol_value<32> symval;
+ if (gsym != NULL)
+ {
+ // This is a global symbol. Determine if we use PLT and if the
+ // final target is THUMB.
+ if (gsym->use_plt_offset(Relocate::reloc_is_non_pic(r_type)))
+ {
+ // This uses a PLT, change the symbol value.
+ symval.set_output_value(this->plt_section()->address()
+ + gsym->plt_offset());
+ psymval = &symval;
+ target_is_thumb = false;
+ }
+ else if (gsym->is_undefined())
+ // There is no need to generate a stub symbol is undefined.
+ return;
+ else
+ {
+ target_is_thumb =
+ ((gsym->type() == elfcpp::STT_ARM_TFUNC)
+ || (gsym->type() == elfcpp::STT_FUNC
+ && !gsym->is_undefined()
+ && ((psymval->value(arm_relobj, 0) & 1) != 0)));
+ }
+ }
+ else
+ {
+ // This is a local symbol. Determine if the final target is THUMB.
+ target_is_thumb = arm_relobj->local_symbol_is_thumb_function(r_sym);
+ }
+
+ // Strip LSB if this points to a THUMB target.
+ if (target_is_thumb
+ && Target_arm<big_endian>::reloc_uses_thumb_bit(r_type)
+ && ((psymval->value(arm_relobj, 0) & 1) != 0))
+ {
+ Arm_address stripped_value =
+ psymval->value(arm_relobj, 0) & ~static_cast<Arm_address>(1);
+ symval.set_output_value(stripped_value);
+ psymval = &symval;
+ }
+
+ // Get the symbol value.
+ Symbol_value<32>::Value value = psymval->value(arm_relobj, 0);
+
+ // Owing to pipelining, the PC relative branches below actually skip
+ // two instructions when the branch offset is 0.
+ Arm_address destination;
+ switch (r_type)
+ {
+ case elfcpp::R_ARM_CALL:
+ case elfcpp::R_ARM_JUMP24:
+ case elfcpp::R_ARM_PLT32:
+ // ARM branches.
+ destination = value + addend + 8;
+ break;
+ case elfcpp::R_ARM_THM_CALL:
+ case elfcpp::R_ARM_THM_XPC22:
+ case elfcpp::R_ARM_THM_JUMP24:
+ case elfcpp::R_ARM_THM_JUMP19:
+ // THUMB branches.
+ destination = value + addend + 4;
+ break;
+ default:
+ gold_unreachable();
+ }
+
+ Stub_type stub_type =
+ Reloc_stub::stub_type_for_reloc(r_type, address, destination,
+ target_is_thumb);
+
+ // This reloc does not need a stub.
+ if (stub_type == arm_stub_none)
+ return;
+
+ // Try looking up an existing stub from a stub table.
+ Stub_table<big_endian>* stub_table =
+ arm_relobj->stub_table(relinfo->data_shndx);
+ gold_assert(stub_table != NULL);
+
+ // Locate stub by destination.
+ Reloc_stub::Key stub_key(stub_type, gsym, arm_relobj, r_sym, addend);
+
+ // Create a stub if there is not one already
+ Reloc_stub* stub = stub_table->find_reloc_stub(stub_key);
+ if (stub == NULL)
+ {
+ // create a new stub and add it to stub table.
+ stub = this->stub_factory().make_reloc_stub(stub_type);
+ stub_table->add_reloc_stub(stub, stub_key);
+ }
+
+ // Record the destination address.
+ stub->set_destination_address(destination
+ | (target_is_thumb ? 1 : 0));
+}
+
+// This function scans a relocation sections for stub generation.
+// The template parameter Relocate must be a class type which provides
+// a single function, relocate(), which implements the machine
+// specific part of a relocation.
+
+// BIG_ENDIAN is the endianness of the data. SH_TYPE is the section type:
+// SHT_REL or SHT_RELA.
+
+// 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.
+
+template<bool big_endian>
+template<int sh_type>
+void inline
+Target_arm<big_endian>::scan_reloc_section_for_stubs(
+ const Relocate_info<32, big_endian>* relinfo,
+ const unsigned char* prelocs,
+ size_t reloc_count,
+ Output_section* output_section,
+ bool needs_special_offset_handling,
+ const unsigned char* view,
+ elfcpp::Elf_types<32>::Elf_Addr view_address,
+ section_size_type)
+{
+ typedef typename Reloc_types<sh_type, 32, big_endian>::Reloc Reltype;
+ const int reloc_size =
+ Reloc_types<sh_type, 32, big_endian>::reloc_size;
+
+ Arm_relobj<big_endian>* arm_object =
+ Arm_relobj<big_endian>::as_arm_relobj(relinfo->object);
+ unsigned int local_count = arm_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);
+
+ typename elfcpp::Elf_types<32>::Elf_WXword r_info = reloc.get_r_info();
+ unsigned int r_sym = elfcpp::elf_r_sym<32>(r_info);
+ unsigned int r_type = elfcpp::elf_r_type<32>(r_info);
+
+ r_type = this->get_real_reloc_type(r_type);
+
+ // Only a few relocation types need stubs.
+ if ((r_type != elfcpp::R_ARM_CALL)
+ && (r_type != elfcpp::R_ARM_JUMP24)
+ && (r_type != elfcpp::R_ARM_PLT32)
+ && (r_type != elfcpp::R_ARM_THM_CALL)
+ && (r_type != elfcpp::R_ARM_THM_XPC22)
+ && (r_type != elfcpp::R_ARM_THM_JUMP24)
+ && (r_type != elfcpp::R_ARM_THM_JUMP19))
+ continue;
+
+ 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;
+ }
+
+ // Get the addend.
+ Stub_addend_reader<sh_type, big_endian> stub_addend_reader;
+ elfcpp::Elf_types<32>::Elf_Swxword addend =
+ stub_addend_reader(r_type, view + offset, reloc);
+
+ const Sized_symbol<32>* sym;
+
+ Symbol_value<32> symval;
+ const Symbol_value<32> *psymval;
+ if (r_sym < local_count)
+ {
+ sym = NULL;
+ psymval = arm_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
+ && !arm_object->is_section_included(shndx)
+ && !(relinfo->symtab->is_section_folded(arm_object, shndx)))
+ {
+ if (comdat_behavior == CB_UNDETERMINED)
+ {
+ std::string name =
+ arm_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<32>::Elf_Addr value =
+ arm_object->map_to_kept_section(shndx, &found);
+ if (found)
+ symval.set_output_value(value + psymval->input_value());
+ else
+ symval.set_output_value(0);
+ }
+ else
+ {
+ symval.set_output_value(0);
+ }
+ symval.set_no_output_symtab_entry();
+ psymval = &symval;
+ }
+ }
+ else
+ {
+ const Symbol* gsym = arm_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<32>*>(gsym);
+ if (sym->has_symtab_index())
+ symval.set_output_symtab_index(sym->symtab_index());
+ else
+ symval.set_no_output_symtab_entry();
+
+ // We need to compute the would-be final value of this global
+ // symbol.
+ const Symbol_table* symtab = relinfo->symtab;
+ const Sized_symbol<32>* sized_symbol =
+ symtab->get_sized_symbol<32>(gsym);
+ Symbol_table::Compute_final_value_status status;
+ Arm_address value =
+ symtab->compute_final_value<32>(sized_symbol, &status);
+
+ // Skip this if the symbol has not output section.
+ if (status == Symbol_table::CFVS_NO_OUTPUT_SECTION)
+ continue;
+
+ symval.set_output_value(value);
+ psymval = &symval;
+ }
+
+ // If symbol is a section symbol, we don't know the actual type of
+ // destination. Give up.
+ if (psymval->is_section_symbol())
+ continue;
+
+ this->scan_reloc_for_stub(relinfo, r_type, sym, r_sym, psymval,
+ addend, view_address + offset);
+ }
+}
+
+// Scan an input section for stub generation.
+
+template<bool big_endian>
+void
+Target_arm<big_endian>::scan_section_for_stubs(
+ const Relocate_info<32, big_endian>* relinfo,
+ unsigned int sh_type,
+ const unsigned char* prelocs,
+ size_t reloc_count,
+ Output_section* output_section,
+ bool needs_special_offset_handling,
+ const unsigned char* view,
+ Arm_address view_address,
+ section_size_type view_size)
+{
+ if (sh_type == elfcpp::SHT_REL)
+ this->scan_reloc_section_for_stubs<elfcpp::SHT_REL>(
+ relinfo,
+ prelocs,
+ reloc_count,
+ output_section,
+ needs_special_offset_handling,
+ view,
+ view_address,
+ view_size);
+ else if (sh_type == elfcpp::SHT_RELA)
+ // We do not support RELA type relocations yet. This is provided for
+ // completeness.
+ this->scan_reloc_section_for_stubs<elfcpp::SHT_RELA>(
+ relinfo,
+ prelocs,
+ reloc_count,
+ output_section,
+ needs_special_offset_handling,
+ view,
+ view_address,
+ view_size);
+ else
+ gold_unreachable();
+}
+
+// Group input sections for stub generation.
+//
+// We goup input sections in an output sections so that the total size,
+// including any padding space due to alignment is smaller than GROUP_SIZE
+// unless the only input section in group is bigger than GROUP_SIZE already.
+// Then an ARM stub table is created to follow the last input section
+// in group. For each group an ARM stub table is created an is placed
+// after the last group. If STUB_ALWATS_AFTER_BRANCH is false, we further
+// extend the group after the stub table.
+
+template<bool big_endian>
+void
+Target_arm<big_endian>::group_sections(
+ Layout* layout,
+ section_size_type group_size,
+ bool stubs_always_after_branch)
+{
+ // Group input sections and insert stub table
+ Layout::Section_list section_list;
+ layout->get_allocated_sections(§ion_list);
+ for (Layout::Section_list::const_iterator p = section_list.begin();
+ p != section_list.end();
+ ++p)
+ {
+ Arm_output_section<big_endian>* output_section =
+ Arm_output_section<big_endian>::as_arm_output_section(*p);
+ output_section->group_sections(group_size, stubs_always_after_branch,
+ this);
+ }
+}
+
+// Relaxation hook. This is where we do stub generation.
+
+template<bool big_endian>
+bool
+Target_arm<big_endian>::do_relax(
+ int pass,
+ const Input_objects* input_objects,
+ Symbol_table* symtab,
+ Layout* layout)
+{
+ // No need to generate stubs if this is a relocatable link.
+ gold_assert(!parameters->options().relocatable());
+
+ // If this is the first pass, we need to group input sections into
+ // stub groups.
+ if (pass == 1)
+ {
+ // Determine the stub group size. The group size is the absolute
+ // value of the parameter --stub-group-size. If --stub-group-size
+ // is passed a negative value, we restict stubs to be always after
+ // the stubbed branches.
+ int32_t stub_group_size_param =
+ parameters->options().stub_group_size();
+ bool stubs_always_after_branch = stub_group_size_param < 0;
+ section_size_type stub_group_size = abs(stub_group_size_param);
+
+ if (stub_group_size == 1)
+ {
+ // Default value.
+ // Thumb branch range is +-4MB has to be used as the default
+ // maximum size (a given section can contain both ARM and Thumb
+ // code, so the worst case has to be taken into account).
+ //
+ // This value is 24K less than that, which allows for 2025
+ // 12-byte stubs. If we exceed that, then we will fail to link.
+ // The user will have to relink with an explicit group size
+ // option.
+ stub_group_size = 4170000;
+ }
+
+ group_sections(layout, stub_group_size, stubs_always_after_branch);
+ }
+
+ // clear changed flags for all stub_tables
+ typedef typename Stub_table_list::iterator Stub_table_iterator;
+ for (Stub_table_iterator sp = this->stub_tables_.begin();
+ sp != this->stub_tables_.end();
+ ++sp)
+ (*sp)->set_has_been_changed(false);
+
+ // scan relocs for stubs
+ for (Input_objects::Relobj_iterator op = input_objects->relobj_begin();
+ op != input_objects->relobj_end();
+ ++op)
+ {
+ Arm_relobj<big_endian>* arm_relobj =
+ Arm_relobj<big_endian>::as_arm_relobj(*op);
+ arm_relobj->scan_sections_for_stubs(this, symtab, layout);
+ }
+
+ bool any_stub_table_changed = false;
+ for (Stub_table_iterator sp = this->stub_tables_.begin();
+ (sp != this->stub_tables_.end()) && !any_stub_table_changed;
+ ++sp)
+ {
+ if ((*sp)->has_been_changed())
+ any_stub_table_changed = true;
+ }
+
+ return any_stub_table_changed;
+}
+
// The selector for arm object files.
template<bool big_endian>
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