This patch is part of a series that enables ARMv8.5-A in GCC and
adds Branch Target Identification Mechanism.
This patch adds a new pass called "bti" which is triggered by the command
line argument -mbranch-protection whenever "bti" is turned on.
The pass iterates through the instructions and adds appropriated BTI
instructions based on the following:
* Add a new "BTI C" at the beginning of a function, unless its already
protected by a "PACIASP". We exempt the functions that are only called
directly.
* Add a new "BTI J" for every target of an indirect jump, jump table
targets, non-local goto targets or labels that might be referenced by
variables, constant pools, etc (NOTE_INSN_DELETED_LABEL).
Since we have already changed the use of indirect tail calls to only x16 and
x17, we do not have to use "BTI JC".
(check patch 3/6).
*** gcc/ChangeLog ***
2018-01-09 Sudakshina Das <sudi.das@arm.com>
Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
* config.gcc (aarch64*-*-*): Add aarch64-bti-insert.o.
* gcc/config/aarch64/aarch64.h: Update comment for TRAMPOLINE_SIZE.
* config/aarch64/aarch64.c (aarch64_asm_trampoline_template): Update
if bti is enabled.
* config/aarch64/aarch64-bti-insert.c: New file.
* config/aarch64/aarch64-passes.def (INSERT_PASS_BEFORE): Insert bti
pass.
* config/aarch64/aarch64-protos.h (make_pass_insert_bti): Declare the
new bti pass.
* config/aarch64/aarch64.md (unspecv): Add UNSPECV_BTI_NOARG,
UNSPECV_BTI_C, UNSPECV_BTI_J and UNSPECV_BTI_JC.
(bti_noarg, bti_j, bti_c, bti_jc): New define_insns.
* config/aarch64/t-aarch64: Add rule for aarch64-bti-insert.o.
*** gcc/testsuite/ChangeLog ***
2018-01-09 Sudakshina Das <sudi.das@arm.com>
* gcc.target/aarch64/bti-1.c: New test.
* gcc.target/aarch64/bti-2.c: New test.
* gcc.target/aarch64/bti-3.c: New test.
* lib/target-supports.exp
(check_effective_target_aarch64_bti_hw): Add new check for BTI hw.
Co-Authored-By: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
From-SVN: r267769
