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We currently use a padding NOP after a Thumb to Arm interworking veneer (BX pc).
The NOP is never executed but may result in a performance penalty on some cores.
For this reason this patch changes the NOPs after Thumb to Arm veneers into B .-2
and adds a note to this in the source code for future reference.
bfd/ChangeLog:
* elf32-arm.c (elf32_thumb2_plt_entry, elf32_arm_plt_thumb_stub,
elf32_arm_stub_long_branch_v4t_thumb_thumb,
elf32_arm_stub_long_branch_v4t_thumb_arm,
elf32_arm_stub_short_branch_v4t_thumb_arm,
elf32_arm_stub_long_branch_v4t_thumb_arm_pic,
elf32_arm_stub_long_branch_v4t_thumb_thumb_pic,
elf32_arm_stub_long_branch_v4t_thumb_tls_pic): Change nop to branch to
previous instruction.
ld/ChangeLog:
* testsuite/ld-arm/cortex-a8-fix-b-plt.d: Update Testcase.
* testsuite/ld-arm/cortex-a8-fix-b-rel-arm.d: Likewise.
* testsuite/ld-arm/cortex-a8-fix-bcc-plt.d: Likewise.
* testsuite/ld-arm/farcall-cond-thumb-arm.d: Likewise.
* testsuite/ld-arm/farcall-mixed-app.d: Likewise.
* testsuite/ld-arm/farcall-mixed-app2.d: Likewise.
* testsuite/ld-arm/farcall-mixed-lib-v4t.d: Likewise.
* testsuite/ld-arm/farcall-thumb-arm-pic-veneer.d: Likewise.
* testsuite/ld-arm/farcall-thumb-arm-short.d: Likewise.
* testsuite/ld-arm/farcall-thumb-arm.d: Likewise.
* testsuite/ld-arm/farcall-thumb-thumb-pic-veneer.d: Likewise.
* testsuite/ld-arm/farcall-thumb-thumb.d: Likewise.
* testsuite/ld-arm/fix-arm1176-on.d: Likewise.
* testsuite/ld-arm/ifunc-10.dd: Likewise.
* testsuite/ld-arm/ifunc-2.dd: Likewise.
* testsuite/ld-arm/ifunc-4.dd: Likewise.
* testsuite/ld-arm/ifunc-6.dd: Likewise.
* testsuite/ld-arm/ifunc-8.dd: Likewise.
* testsuite/ld-arm/jump-reloc-veneers-long.d: Likewise.
* testsuite/ld-arm/mixed-app.d: Likewise.
* testsuite/ld-arm/thumb2-b-interwork.d: Likewise.
* testsuite/ld-arm/tls-longplt.d: Likewise.
* testsuite/ld-arm/tls-thumb1.d: Likewise.
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BFD's bfd_get_mach () function returns a bfd specific value representing
the architecture of the target which is populated from the Tag_CPU_arch
build attribute value of that target. Among other users of that
interfacem, objdump which uses it to print the architecture version of
the binary being examinated and to decide what instruction is available
if run with "-m arm" via its own mapping from bfd_mach_arm_X values to
feature bits available.
However, both BFD and objdump's most recent known architecture is
Armv5TE. When encountering a newer architecture bfd_get_mach will return
bfd_mach_arm_unknown. This is unfortunate since objdump uses that value
to allow all instructions on all architectures which is already what it
does by default, making the "-m arm" trick useless.
This patch updates BFD and objdump's knowledge of Arm architecture
versions up to the latest Armv8-M Baseline and Mainline, Armv8-R and
Armv8.4-A architectures. Since several architecture versions (eg. 8.X-A)
share the same Tag_CPU_arch build attribute value and
bfd_mach_arm values, the mapping from bfd machine value to feature bits
need to return the most featureful feature bits that would yield the
given bfd machine value otherwise some instruction would not disassemble
under "-m arm" mode. The patch rework that mapping to make this clearer
and simplify writing the mapping rules. In particular, for simplicity
all FPU instructions are allowed in all cases.
Finally, the patch also rewrite the cpu_arch_ver table in GAS to use the
TAG_CPU_ARCH_X macros rather than hardcode their value.
2018-07-02 Thomas Preud'homme <thomas.preudhomme@arm.com>
bfd/
* archures.c (bfd_mach_arm_5TEJ, bfd_mach_arm_6, bfd_mach_arm_6KZ,
bfd_mach_arm_6T2, bfd_mach_arm_6K, bfd_mach_arm_7, bfd_mach_arm_6M,
bfd_mach_arm_6SM, bfd_mach_arm_7EM, bfd_mach_arm_8, bfd_mach_arm_8R,
bfd_mach_arm_8M_BASE, bfd_mach_arm_8M_MAIN): Define.
* bfd-in2.h: Regenerate.
* cpu-arm.c (arch_info_struct): Add entries for above new
bfd_mach_arm values.
* elf32-arm.c (bfd_arm_get_mach_from_attributes): Add Tag_CPU_arch to
bfd_mach_arm mapping logic for pre Armv4 and Armv5TEJ and later
architectures. Force assert failure for any new Tag_CPU_arch value.
gas/
* config/tc-arm.c (cpu_arch_ver): Use symbolic TAG_CPU_ARCH macros
rather than hardcode their values.
ld/
* arm-dis.c (select_arm_features): Fix typo in heading comment. Allow
all FPU features and add mapping from new bfd_mach_arm values to
allowed CPU feature bits.
opcodes/
* testsuite/ld-arm/tls-descrelax-be8.d: Add architecture version in
expected result.
* testsuite/ld-arm/tls-descrelax-v7.d: Likewise.
* testsuite/ld-arm/tls-longplt-lib.d: Likewise.
* testsuite/ld-arm/tls-longplt.d: Likewise.
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gas/
2014-11-21 Terry Guo <terry.guo@arm.com>
* config/tc-arm.c (md_assemble): Do not consider relaxation.
(md_convert_frag): Test and set target arch attribute accordingly.
(aeabi_set_attribute_string): Turn it into a global function.
* config/tc-arm.h (md_post_relax_hook): Enable it for ARM target.
(aeabi_set_public_attributes): Declare it.
gas/testsuite/
2014-11-21 Terry Guo <terry.guo@arm.com>
* gas/arm/attr-arch-assumption.d: New file.
* gas/arm/attr-arch-assumption.s: Likewise.
ld/testsuite/
2014-11-21 Terry Guo <terry.guo@arm.com>
* ld-arm/tls-longplt-lib.s: Require ARMv6T2.
* ld-arm/tls-longplt.s: Likewise.
* ld-arm/tls-longplt-lib.d: Updated.
* ld-arm/tls-longplt.d: Likewise.
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bfd/
* elf32-arm.c (arm_stub_is_thumb): Add
arm_stub_long_branch_v4t_thumb_tls_pic.
(elf32_arm_final_link_relocate): TLS stubs are always ARM.
Handle Thumb stubs.
ld/testsuite/
* ld-arm/tls-longplt.d: Update expected output.
* ld-arm/tls-thumb1.d: Ditto.
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* reloc.c (BFD_RELOC_ARM_TLS_GOTDESC, BFD_RELOC_ARM_TLS_CALL,
BFD_RELOC_ARM_THM_TLS_CALL, BFD_RELOC_ARM_TLS_DESCSEQ,
BFD_RELOC_ARM_THM_TLS_DESCSEQ, BFD_RELOC_ARM_TLS_DESC): New
relocations.
* libbfd.h: Rebuilt.
* bfd-in2.h: Rebuilt.
* elf32-arm.c (elf32_arm_howto_table_1): Add new relocations.
(elf32_arm_reloc_map): Likewise.
(tls_trampoline, dl_tlsdesc_lazy_trampoline): New PLT templates.
(elf32_arm_stub_long_branch_any_tls_pic,
elf32_arm_stub_long_branch_v4t_thumb_tls_pic): New stub templates.
(DEF_STUBS): Add new stubs.
(struct_elf_arm_obj_data): Add local_tlsdesc_gotent field.
(elf32_arm_local_tlsdesc_gotent): New.
(GOT_TLS_GDESC): New mask.
(GOT_TLS_GD_ANY): Define.
(struct elf32_arm_link_hash_entry): Add tlsdesc_got field.
(elf32_arm_compute_jump_table_size): New.
(struct elf32_arm_link_hash_table): Add next_tls_desc_index,
num_tls_desc, dt_tlsdesc_plt, dt_tlsdesc_got, tls_trampoline,
sgotplt_jump_table_size fields.
(elf32_arm_link_hash_newfunc): Initialize tlsdesc_got field.
(elf32_arm_link_hash_table_create): Initialize new fields.
(arm_type_of_stub): Check TLS desc relocs too.
(elf32_arm_stub_name): TLS desc relocs can be shared.
(elf32_arm_tls_transition): Determine relaxation.
(arm_stub_required_alignment): Add tls stubs.
(elf32_arm_size_stubs): Likewise.
(elf32_arm_tls_relax): Perform TLS relaxing.
(elf32_arm_final_link_relocate): Process TLS DESC relocations.
(IS_ARM_TLS_GNU_RELOC): New.
(IS_ARM_TLS_RELOC): Use it.
(elf32_arm_relocate_section): Perform TLS relaxing.
(elf32_arm_check_relocs): Anticipate TLS relaxing, process tls
desc relocations.
(allocate_dynrelocs): Allocate tls desc relcoations.
(elf32_arm_output_arch_local_syms): Emit tls trampoline mapping
symbols.
(elf32_arm_size_dynamic_sections): Allocate tls trampolines and
got slots.
(elf32_arm_always_size_sections): New. Create _TLS_MODULE_BASE
symbol.
(elf32_arm_finish_dynamic_symbol): Adjust.
(arm_put_trampoline): New.
(elf32_arm_finish_dynamic_sections): Emit new dynamic tags and tls
trampolines.
(elf_backend_always_size_sections): Define.
include/elf/
* arm.h (R_ARM_TLS_DESC, R_ARM_TLS_GOTDESC, R_ARM_TLS_CALL,
R_ARM_TLS_DESCSEQ, T_ARM_THM_TLS_CALL, R_ARM_THM_TLS_DESCSEQ): New
relocations.
gas/
* doc/c-arm.texi: Document TLSDESC and TLSCALL relocations, and
.tlsdescseq directive.
* config/tc-arm.c (arm_typed_reg_parse): Check for potential reloc
following a symbol.
(s_arm_tls_descseq): New directive.
(md_pseudo_table): Add it.
(encode_branch): Allow TLS_CALL relocs too.
(do_t_blx, do_t_branch23): Use encode_branch.
(reloc_names): Add tlsdesc and tlscall.
(md_apply_fix): Process tls desc relocations.
(tc_gen_reloc): Likewise.
(arm_fix_adjustable): Likewise.
gas/testsuite/
* gas/arm/tls.s: Add tlsdesc tests.
* gas/arm/tls.d: Adjust.
ld/testsuite/
* ld-arm/arm-elf.exp: Added tests for new TLS handling
relocations.
* ld-arm/tls-descrelax-be32.d: New.
* ld-arm/tls-descrelax-be32.s: New.
* ld-arm/tls-descrelax-be8.d: New.
* ld-arm/tls-descrelax-be8.s: New.
* ld-arm/tls-descrelax-v7.d: New.
* ld-arm/tls-descrelax-v7.s: New.
* ld-arm/tls-descrelax.d: New.
* ld-arm/tls-descrelax.s: New.
* ld-arm/tls-descseq.d: New.
* ld-arm/tls-descseq.r: New.
* ld-arm/tls-descseq.s: New.
* ld-arm/tls-gdesc-got.d: New.
* ld-arm/tls-gdesc-got.s: New.
* ld-arm/tls-gdesc-nlazy.g: New.
* ld-arm/tls-gdesc-nlazy.s: New.
* ld-arm/tls-gdesc.d: New.
* ld-arm/tls-gdesc.r: New.
* ld-arm/tls-gdesc.s: New.
* ld-arm/tls-gdierelax.d: New.
* ld-arm/tls-gdierelax.s: New.
* ld-arm/tls-gdierelax2.d: New.
* ld-arm/tls-gdierelax2.s: New.
* ld-arm/tls-gdlerelax.d: New.
* ld-arm/tls-gdlerelax.s: New.
* ld-arm/tls-lib-loc.d: New.
* ld-arm/tls-lib-loc.r: New.
* ld-arm/tls-lib-loc.s: New.
* ld-arm/tls-longplt-lib.d: New.
* ld-arm/tls-longplt-lib.s: New.
* ld-arm/tls-longplt.d: New.
* ld-arm/tls-longplt.s: New.
* ld-arm/tls-mixed.r: New.
* ld-arm/tls-mixed.s: New.
* ld-arm/tls-thumb1.d: New.
* ld-arm/tls-thumb1.s: New.
* ld-arm/arm-elf.exp: New.
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