PR gold/21066
* gc.h (gc_process_relocs): Track relocations in .eh_frame sections
when ICF is enabled, even though the .eh_frame sections themselves
are not foldable.
* icf.cc (get_section_contents): Change arguments to permit operation
on just part of a section. Include extra identity regions in the
referring section's contents recursively.
(match_sections): Lock object here instead of in get_section_contents
so that get_section_contents can operate recursively.
(Icf::add_ehframe_links): New method.
(Icf::find_identical_sections): Pass .eh_frame sections to
add_ehframe_links(). Increase default iteration count from 2 to 3
because handling exception info typically requires one extra iteration.
* icf.h (Icf::extra_identity_list_): New data member with accessor.
(is_section_foldable_candidate): Include .gcc_except_table sections.
* options.h: Update documentation for new default ICF iteration count.
* testsuite/Makefile.am (icf_test_pr21066): New test case.
* testsuite/Makefile.in: Regenerate.
* testsuite/icf_test_pr21066.cc: New source file.
* testsuite/icf_test_pr21066.sh: New test script.
This option does not merge certain text sections with prefixes
.text.hot, .text.unlikely, .text.startup and .text.exit.
* layout.cc (Layout::default_section_order): Check for text section
prefixes.
(Layout::text_section_name_mapping): New static member.
(Layout::text_section_name_mapping_count): New static member.
(Layout::match_section_name): New static function.
(Layout::output_section_name): Check for text section prefixes.
* layout.h (Output_section_order::ORDER_TEXT_HOT): New enum value.
(Output_section_order::ORDER_TEXT_STARTUP): New enum value.
(Output_section_order::ORDER_TEXT_EXIT): New enum value.
(Output_section_order::ORDER_TEXT_UNLIKELY): New enum value.
(Layout::text_section_name_mapping): New static member.
(Layout::text_section_name_mapping_count): New static member.
(Layout::match_section_name): New static function.
* options.h (keep_text_section_prefix): New -z option.
* testsuite/Makefile.am (keep_text_section_prefix): New test.
* testsuite/Makefile.in: Regenerate.
* testsuite/keep_text_section_prefix.cc: New test source.
* testsuite/keep_text_section_prefix.sh: New test script.
This reverts most of commit 1be5d8d3bb.
Left in place are addition of --no-plt-align to some ppc32 ld tests
and the ld.texinfo --no-plt-thread-safe fix.
This is in preparation for the next patch adding Spectre variant 2
mitigation for PowerPC and PowerPC64. Besides tidying code involved
in stub output (to reduce the number of places where bctr is output),
the patch adds some user visible features:
1) PowerPC64 ELFv2 global entry stubs now are aligned under the
control of --plt-align, with a default alignment of 32 bytes.
2) PowerPC64 __glink_PLTresolve is no longer padded out with nops.
3) PowerPC32 PLT stubs are aligned under the control of --plt-align,
with the default alignment being 16 bytes as before.
4) The PowerPC32 branch/nop table emitted before __glink_PLTresolve
is now smaller in many cases. It was sized incorrectly when the
__tls_get_addr_opt stub was used, and unnecessarily included space
for local ifuncs.
bfd/
* elf32-ppc.c (GLINK_ENTRY_SIZE): Add parameters, handle
__tls_get_addr_opt, and alignment sizing.
(TLS_GET_ADDR_GLINK_SIZE): Delete.
(is_nonpic_glink_stub): Don't use GLINK_ENTRY_SIZE.
(ppc_elf_get_synthetic_symtab): Recognize stubs spaced at 4, 6,
or 8 insns.
(ppc_elf_link_hash_table_create): Init new ppc_elf_params field.
(allocate_dynrelocs): Use new GLINK_ENTRY_SIZE.
(ppc_elf_size_dynamic_sections): Likewise. Size branch table
by PLT reloc count.
(write_glink_stub): Handle __tls_get_addr_opt stub.
Pad out to size given by GLINK_ENTRY_SIZE.
(ppc_elf_relocate_section): Adjust write_glink_stub call.
(ppc_elf_finish_dynamic_symbol): Likewise.
(ppc_elf_finish_dynamic_sections): Write PLTresolve without using
insn array since so many need rewriting.
* elf32-ppc.h (struct ppc_elf_params): Add plt_stub_align.
* elf64-ppc.c (GLINK_PLTRESOLVE_SIZE): Rename from
GLINK_CALL_STUB_SIZE. Add htab param and evaluate to size without
nops. Adjust all uses.
(ppc64_elf_get_synthetic_symtab): Don't use GLINK_CALL_STUB_SIZE
in glink_vma calculation.
(struct ppc_link_hash_table): Add global_entry section pointer.
(create_linkage_sections): Create separate section for global
entry stubs.
(PPC_LO, PPC_HI, PPC_HA): Move earlier.
(size_global_entry_stubs): Handle sizing for aligned stubs.
(ppc64_elf_size_dynamic_sections): Handle global_entry alloc,
and don't stash end of glink branch table in rawsize.
(ppc_build_one_stub): Rewrite stub size calculations.
(build_global_entry_stubs): Use new section.
(ppc64_elf_build_stubs): Don't pad __glink_PLTresolve with nops.
Build lazy link stubs out to end of section. Build global entry
stubs in new section.
gold/
* options.h (plt_align): Support for PowerPC32 too.
* powerpc.cc (Stub_table::stub_align): Heed --plt-align for 32-bit.
(Stub_table::plt_call_size, branch_stub_size): Tidy.
(Stub_table::plt_call_align): Implement using stub_align.
(Output_data_glink::global_entry_align): New function.
(Output_data_glink::global_entry_off): New function.
(Output_data_glink::global_entry_address): Use global_entry_off.
(Output_data_glink::pltresolve_size): New function, replacing
pltresolve_size_ constant. Update all uses.
(Output_data_glink::add_global_entry): Align offset.
(Output_data_glink::set_final_data_size): Use global_entry_align.
(Stub_table::do_write): Don't pad __glink_PLTrelsolve with nops.
Tidy stub output. Use global_entry_off.
ld/
* emultempl/ppc32elf.em (params): Init new field.
(enum ppc32_opt): New enum to define OPTION_* values. Add
OPTION_PLT_ALIGN and OPTION_NO_PLT_ALIGN.
(PARSE_AND_LIST_LONGOPTS): Handle new options.
(PARSE_AND_LIST_ARGS_CASES): Likewise.
(PARSE_AND_LIST_OPTIONS): Likewise. Break up help output.
* emultempl/ppc64elf.em (ppc_add_stub_section): Init alignment
correctly for negative --plt-stub-align.
* testsuite/ld-powerpc/elfv2exe.d,
* testsuite/ld-powerpc/elfv2so.d,
* testsuite/ld-powerpc/relbrlt.d,
* testsuite/ld-powerpc/relbrlt.s,
* testsuite/ld-powerpc/tlsexe.d,
* testsuite/ld-powerpc/tlsexe.r,
* testsuite/ld-powerpc/tlsexe32.d,
* testsuite/ld-powerpc/tlsexe32.g,
* testsuite/ld-powerpc/tlsexe32.r,
* testsuite/ld-powerpc/tlsexetoc.d,
* testsuite/ld-powerpc/tlsexetoc.r,
* testsuite/ld-powerpc/tlsopt5_32.d,
* testsuite/ld-powerpc/tlsso.d,
* testsuite/ld-powerpc/tlstocso.d: Update for changed stub order.
PR 22042 complained that garbage text was being printed in the help
for the -fuse-ld option; this was caused by passing an empty string
to the gettext() function, which sometimes returns garbage when passed
an empty string. The quick fix was to replace "" with NULL as the helparg,
but that changed the parsing of the option, as gold uses the helparg to
determine whether an option takes an argument. This patch adds a
non-empty helparg string to fix both problems.
gold/
PR gold/22694
* options.h (-fuse-ld): Add correct helparg.
2017-10-04 Sriraman Tallam <tmsriram@google.com>
* options.h (-z,text_unlikely_segment): New option.
* layout.cc (Layout::layout): Create new output section
for .text.unlikely sections with the new option.
(Layout::segment_precedes): Check for the new option
when segment flags match.
* testsuite/text_unlikely_segment.cc: New test source.
* testsuite/text_unlikely_segment.sh: New test script.
* testsuite/Makefile.am (text_unlikely_segment): New test.
* testsuite/Makefile.in: Regenerate.
gold/
* arm.cc (Stub::do_fixed_endian_write):Far call stubs support for arm
in the be8 mode.
* testsuite/Makefile.am: New test cases.
* testsuite/Makefile.in: Regenerate.
* testsuite/arm_farcall_arm_arm_be8.sh: New script for arm to arm far
call stubs.
* testsuite/arm_farcall_thumb_thumb_be8.sh: New script for thumb to
thumb far call stubs.
The trouble with stubs per output section is that ppc32 uses a plt
stub as the address of a global function. This needs to be unique,
otherwise we'll get multiple addresses for a function.
Obviously this is only a partial solution, since ppc32 will get
multiple stubs when code is larger than 33M. A proper fix will
involve selecting a unique stub to use for non-branch relocs.
* options.h (stub-group-multi): Default to true. Add
--no-stub-group-multi.
This implements the special __tls_get_addr_opt call stub for powerpc
gold that returns __thread variable addresses without actually making
a call to __tls_get_addr in most cases. Shared libraries that are
loaded at program load time (ie. dlopen is not used) have a known
layout for their __thread variables, and thus DTPMOD64/DPTREL64 pairs
describing those variables can be set up by ld.so for the
__tls_get_addr_opt call stub fast exit.
Ref https://sourceware.org/ml/libc-alpha/2015-03/msg00626.html
I really, really wish I'd used a differently versioned __tls_get_addr
symbol than the base symbol to indicate glibc support for the
optimized call, rather than having glibc export __tls_get_addr_opt. A
lot of the messing around here, flipping symbols from __tls_get_addr
to __tls_get_addr_opt, is caused by that decision. About the only
benefit is that a user can see at a glance that their disassembled
code is calling __tls_get_addr via the fancy call stub.. Anyway, we
need references to __tls_get_addr to seem like they were to
__tls_get_addr_opt, and in cases like the tsan interceptor, a
definition of __tls_get_addr to seem like one of __tls_get_addr_opt
as well. That's the reason for Symbol::clear_in_reg and
Symbol_table::clone, and why symbols are substituted in Scan::global
and other places dealing with dynamic linking.
elfcpp/
* elfcpp.h (DT_PPC_OPT): Define.
* powerpc.h (PPC_OPT_TLS): Define.
gold/
* options.h (tls_get_addr_optimize): New option.
* symtab.h (Symbol::clear_in_reg, clone): New functions.
(Sized_symbol::clone): New function.
(Symbol_table::clone): New function.
* resolve.cc (Symbol::clone, Sized_symbol::clone): New functions.
* powerpc.cc (Target_powerpc::has_tls_get_addr_opt_,
tls_get_addr_, tls_get_addr_opt_): New vars.
(Target_powerpc::tls_get_addr_opt, tls_get_addr,
is_tls_get_addr_opt, replace_tls_get_addr,
set_has_tls_get_addr_opt, stk_linker): New functions.
(Target_powerpc::Track_tls::maybe_skip_tls_get_addr_call): Add
target param. Update callers. Compare symbols rather than names.
(Target_powerpc::do_define_standard_symbols): Init tls_get_addr_
and tls_get_addr_opt_.
(Target_powerpc::Branch_info::mark_pltcall): Translate tls_get_addr
sym to tls_get_addr_opt.
(Target_powerpc::Branch_info::make_stub): Likewise.
(Stub_table::define_stub_syms): Likewise.
(Target_powerpc::Scan::global): Likewise.
(Target_powerpc::Relocate::relocate): Likewise.
(add_3_12_2, add_3_12_13, bctrl, beqlr, cmpdi_11_0, cmpwi_11_0,
ld_11_1, ld_11_3, ld_12_3, lwz_11_3, lwz_12_3, mr_0_3, mr_3_0,
mtlr_11, std_11_1): New constants.
(Stub_table::eh_frame_added_): Delete.
(Stub_table::tls_get_addr_opt_bctrl_, plt_fde_len_, plt_fde_): New vars.
(Stub_table::init_plt_fde): New functions.
(Stub_table::add_eh_frame, replace_eh_frame): Move definition out
of line. Init and use plt_fde_.
(Stub_table::plt_call_size): Return size for tls_get_addr stub.
Extract alignment code to..
(Stub_table::plt_call_align): ..this new function. Adjust all callers.
(Stub_table::add_plt_call_entry): Set has_tls_get_addr_opt and
tls_get_addr_opt_bctrl, and align after that.
(Stub_table::do_write): Write out tls_get_addr stub.
(Target_powerpc::do_finalize_sections): Emit DT_PPC_OPT
PPC_OPT_TLS/PPC64_OPT_TLS bit.
(Target_powerpc::Relocate::relocate): Don't check for or modify
nop following bl for tls_get_addr stub.
This adds a --no-tls-optimize option for people who want to keep
__tls_get_addr calls in an executable rather than optimizing such code
sequences to IE/LE.
Also tidy some formatting errors, rename a variable to better reflect
its use, and tweak two functions that create pairs of GOT entries to
first check whether the GOT entry already exists before potentially
inserting the header via reserve(2). Without the check it is possible
to waste one GOT entry.
* options.h (no_tls_optimize): New powerpc option.
* powerpc.cc (Target_powerpc::abiversion, set_abiversion): Formatting.
(Target_powerpc::stk_toc): Formatting, fix comment.
(Target_powerpc::Track_tls::tls_get_addr_state): Rename from
tls_get_addr.
(Target_powerpc::optimize_tls_gd, optimize_tls_ld, optimize_tls_ie):
Return TLSOPT_NONE when !tls_optimize.
(Target_powerpc::add_global_pair_with_rel): Check
for existing reloc before reserving.
(Target_powerpc::add_local_tls_pair): Likewise.
elfcpp/
* elfcpp.h (DT_PPC64_OPT): Define.
* powerpc.h (PPC64_OPT_TLS, PPC64_OPT_MULTI_TOC,
PPC64_OPT_LOCALENTRY): Define.
gold/
* options.h (General_options): Add plt_localentry.
* powerpc.cc (Target_powerpc::st_other): New function.
(Target_powerpc::plt_localentry0_, plt_localentry0_init_,
has_localentry0_): New vars.
(Target_powerpc::plt_localentry0, set_has_localentry0,
is_elfv2_localentry0): New functions.
(Target_powerpc::Branch_info::mark_pltcall): Don't set tocsave or
return true for localentry:0 calls.
(Stub_table::Plt_stub_ent::localentry0_): New var.
(Stub_table::add_plt_call_entry): Set localentry0_ and has_localentry0_.
Don't set r2save_ for localentry:0 calls.
(Output_data_glink::do_write): Save r2 in __glink_PLTresolve for elfv2.
(Target_powerpc::scan_relocs): Default plt_localentry0_.
(Target_powerpc::do_finalize_sections): Set DT_PPC64_OPT.
(Target_powerpc::Relocate::relocate): Don't require nop following
calls for localentry:0 plt calls, and don't change nop.
Added just to accept, and ignore. gcc since 2015-10-21, when
configured with --enable-secureplt passes this option to the linker.
As powerpc gold cannot link --bss-plt code successfully, gold needs to
accept the option or the gcc specs file needs to be changed.
The patch also make gold detect --bss-plt code and error out rather
than producing a binary that crashes.
* options.h: Add --secure-plt option.
* powerpc.cc (Target_powerpc::Scan::local): Detect and error
on -fPIC -mbss-plt code.
(Target_powerpc::Scan::global): Likewise.
gold/
PR gold/17643
* options.h (-z bndplt): New option.
* x86_64.cc (Output_data_plt_x86_64::regular_count): New method.
(Output_data_plt_x86_64::address_for_global): Move implementation into
virtual method.
(Output_data_plt_x86_64::address_for_local): Likewise.
(Output_data_plt_x86_64::got): New method.
(Output_data_plt_x86_64::got_plt): New method.
(Output_data_plt_x86_64::got_irelative): New method.
(Output_data_plt_x86_64::do_address_for_global): New virtual method.
(Output_data_plt_x86_64::do_address_for_local): New virtual method.
(class Output_data_plt_x86_64_bnd): New class.
(Target_x86_64::do_make_data_plt): Move out of line and specialize
for each size (both overloads).
(Output_data_plt_x86_64::set_final_data_size): Cosmetic changes.
* testsuite/Makefile.am (bnd_plt_1): New test case.
(bnd_ifunc_1): New test case.
(bnd_ifunc_2): New test case.
* testsuite/Makefile.in: Regenerate.
* testsuite/bnd_ifunc_1.s: New source file.
* testsuite/bnd_ifunc_1.sh: New shell script.
* testsuite/bnd_ifunc_2.s: New source file.
* testsuite/bnd_ifunc_2.sh: New shell script.
* testsuite/bnd_plt_1.s: New source file.
* testsuite/bnd_plt_1.sh: New shell script.
gold/
PR gold/20749
* options.h (--orphan-handling): New option.
(General_options::Orphan_handling): New enum.
(General_options::orphan_handling_enum): New method.
(General_options::set_orphan_handling_enum): New method.
(General_options::orphan_handling_enum_): New data member.
* options.cc (General_options::General_options): Initialize new member.
(General_options::finalize): Convert --orphan-handling argument to enum.
* script-sections.cc (Script_sections::output_section_name): Check it.
Adds a new option, defaulting to off, that allows a group of stubs to
serve multiple output sections. Prior to this patch powerpc gold
allowed this unconditionally, which is a little unsafe with clever
code that discards/reuses sections at runtime.
* options.h (--stub-group-multi): New PowerPC option.
* powerpc.cc (Stub_control): Add multi_os_ var and param
to constructor. Sort start_ var later. Comment State.
(Stub_control::can_add_to_stub_group): Heed multi_os_.
(Target_powerpc::group_sections): Update.
Gold attaches stubs to an existing section in contrast to ld.bfd which
inserts a new section for stubs. If we want stubs before branches,
then the stubs must be added to the previous section. Adding to the
previous section is a disaster if there is a large gap between the
previous section and the group.
PR gold/20878
* powerpc.cc (Stub_control): Replace stubs_always_before_branch_
with stubs_always_after_branch_, group_end_addr_ with
group_start_addr_.
(Stub_control::can_add_to_stub_group): Rewrite to suit scanning
sections by increasing address.
(Target_powerpc::group_sections): Scan that way. Delete corner
case.
* options.h (--stub-group-size): Update help string.
gold/
PR gold/18989
* options.cc (General_options::object_format_to_string): New function.
(General_options::copy_from_posdep_options): New function.
(General_options::parse_push_state): New function.
(General_options::parse_pop_state): New function.
* options.h (--push-state, --pop-state): New options.
(General_options::object_format_to_string): New method.
(General_options::set_incremental_disposition): New method.
(General_options::copy_from_posdep_options): New method.
(General_options::options_stack_): New data member.
gold/
PR gold/20346
* options.cc (One_option::print): Print "(default)" when appropriate.
* options.h: Clean up and re-sort options.
(One_option::is_default): New data member.
(One_option::One_option): Add is_default parameter; adjust all calls.
(DEFINE_var): Add is_default__ parameter; adjust all calls.
(DEFINE_bool): Set is_default based on default_value__.
(DEFINE_bool_ignore): New macro.
(--no-eh-frame-hdr): New option.
(--enable-new-dtags): Remove mention of DT_FLAGS.
Add a configure option --enable-relro to decide whether -z relro should
be enabled by default. Default to yes.
PR ld/20283
* NEWS: Mention --enable-relro.
* configure.ac: Add --enable-relro.
(DEFAULT_LD_Z_RELRO): New. Set by --enable-relro and default
to 1.
* config.in: Regenerated.
* configure: Likewise.
* options.h (General_options::relro): Default to
DEFAULT_LD_Z_RELRO.
gold/
PR gold/18780
* arm.cc (Target_arm::do_make_data_plt): Choose PLT generator based
on value of --long-plt flag.
(Output_data_plt_arm_standard::do_get_plt_entry_size): Moved to
Output_data_plt_arm_short.
(Output_data_plt_arm_standard::do_fill_plt_entry): Likewise.
(Output_data_plt_arm_standard::plt_entry): Likewise.
(Output_data_plt_arm_standard::do_fill_first_plt_entry): Fix
variable reference.
(Output_data_plt_arm_short): New class.
(Output_data_plt_arm_short::do_fill_plt_entry): Error out on too large
PLT offsets instead of asserting.
(Output_data_plt_arm_long): New class.
* options.h (General_options): Define --long-plt flag.
Gold does not support all the emulations that Gnu ld does, and supports
only one spelling per target. The -m option is used only in the rare case
where there are no ELF input files, and we produce an empty output file.
In those cases, users are expected to supply a -m option naming one of
the supported emulations. In the many cases where a build script provides
an unnecessary -m option naming an emulation that gold does not support,
we will simply ignore the option, as we did before the reverted patch.
gold/
PR gold/19119
PR gold/19172
PR gold/19197
Revert commit 6457197210:
2015-10-16 H.J. Lu <hongjiu.lu@intel.com>
* options.h (General_options): Remove "obsolete" from -m.
* parameters.cc (set_parameters_target): Check if input target
is compatible with output emulation set by "-m emulation".
With --no-apply-dynamic-relocs on aarch64 targets, gold will not apply
link-time values for absolute relocations that become dynamic relocations.
This provides a workaround for broken Android dynamic linkers that use
the link-time value as an extra addend to the relocation.
gold/
PR gold/19163
* aarch64.cc (Target_aarch64::Relocate::relocate): Don't apply
certain relocations if --no-apply-dynamic-relocs is set.
* options.h (--apply-dynamic-relocs): New aarch64-specific option.
Gold shouldn't ignore "-m emulation" command line option, which may
lead to incorrect output.
PR gold/19119
* options.h (General_options): Remove "obsolete" from -m.
* parameters.cc (set_parameters_target): Check if input target
is compatible with output emulation set by "-m emulation".
gold/ChangeLog:
* aarch64.cc (AArch64_insn_utilities::BYTES_PER_INSN): Move
defintion outside class definition.
(AArch64_insn_utilities::AARCH64_ZR): New static constant.
(AArch64_insn_utilities::aarch64_op31): New member.
(AArch64_insn_utilities::aarch64_ra): New member.
(AArch64_insn_utilities::aarch64_mac): New member.
(AArch64_insn_utilities::aarch64_mlxl): New member.
(ST_E_835769): New global enum member.
(Stub_table::relocate_stubs): Add 835769 handler.
(Stub_template_repertoire::Stub_template_repertoire): Install new
stub type.
(AArch64_relobj::scan_errata): This func is renamed from
scan_erratum_843419.
(AArch64_relobj::do_count_local_symbols): Add 835769 handler.
(AArch64_relobj::do_relocate_sections): Add 835769 handler.
(AArch64_relobj::scan_sections_for_stubs): Add 835769 handler.
(Target_aarch64::scan_erratum_835769_span): New method.
(Target_aarch64::create_erratum_stub): New method.
(Target_aarch64::is_erratum_835769_sequence): New method.
(Target_aarch64::scan_erratum_843419_sequence): Move part of the
code into create_erratum_stub.
* options.h (fix_cortex_a53_835769): New option.
Add --discard-none to keep all local symbols.
gold/
PR gold/17498
* object.cc (Sized_relobj_file::do_count_local_symbols): Discard
temporary locals in merge sections.
* options.cc (General_options::parse_discard_all): New method.
(General_options::parse_discard_locals): New method.
(General_options::parse_discard_none): New method.
(General_options::General_options): Initialize discard_locals_.
* options.h (--discard-all): Convert to special option.
(--discard-locals): Likewise.
(--discard-none): New option.
(General_options::discard_all): New method.
(General_options::discard_locals): New method.
(General_options::discard_sec_merge): New method.
(General_options::Discard_locals): New enum.
(General_options::discard_locals_): New data member.
Keep gold consistent with bfd erratum-fixing option names, so as to
ease life in Makefile/scripts.
gold/
* options.h (--fix-cortex-a53-843419): Rename option.
* aarch64.cc (AArch64_relobj::do_count_local_symbols): Use renamed
option.
(AArch64_relobj::scan_sections_for_stubs): Use renamed option.
This patch adds option --weak-unresolved-symbols to treat unresolved symbols as
weak references. This is helpful when we want the link to succeed with unresolved
symbols and the dynamic loader to not complain at run-time. Option
--warn-unresolved-symbols lets the link succeed but could fail at run-time with
unresolved symbol warnings especially when the unresolved symbols have GOT entries
and dynamic relocations against them, like when -fPIE is used.
It implemented scanning the binary and reporting occurrences to users
when '--fix-cortex-a53' is turned on. With this, gold users will be
able to see if or not there are such erratum occurrences in the output
binary. Also included in the CL is reading/recording mapping symbols,
which is needed during scan.
gold/ChangeLog:
* aarch64.cc (AArch64_insn_utilities): New utility class.
(AArch64_relobj::Mapping_symbol_position): New struct.
(AArch64_relobj::Mapping_symbol_info): New typedef.
(AArch64_relobj::do_count_local_symbols): New function overriding
parent's implementation.
(AArch64_relobj::mapping_symbol_info_): New member
(AArch64_relobj::scan_erratum_843419): New method.
(Target_aarch64::scan_erratum_843419_span): New method.
(Target_aarch64::is_erratum_843419_sequence): New method.
* options.h (fix_cortex_a53): New option.
