On 18/08/2022 01:00, Andrew Pinski via Gcc-patches wrote:
On Fri, Nov 2, 2018 at 11:39 AM Sudakshina Das <sudi....@arm.com> wrote:
Hi
This patch is part of a series that enables ARMv8.5-A in GCC and
adds Branch Target Identification Mechanism.
(https://developer.arm.com/products/architecture/cpu-architecture/a-profile/exploration-tools)
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/PACIBSP". We exempt the functions that are
only called directly.
Coming back to this because the check only_called_directly_p does not
work if the linker will insert a veneer as the compiler does not know
about that.
This is recorded as https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106671 .
I think the linker has to make sure to insert a veneer that ends with a
branch in that case.
R.
Thanks,
Andrew Pinski
* 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).
Bootstrapped and regression tested with aarch64-none-linux-gnu. Added
new tests.
Is this ok for trunk?
Thanks
Sudi
*** gcc/ChangeLog ***
2018-xx-xx Sudakshina Das <sudi....@arm.com>
Ramana Radhakrishnan <ramana.radhakrish...@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 (bti_nop): Define.
* config/aarch64/t-aarch64: Add rule for aarch64-bti-insert.o.
*** gcc/testsuite/ChangeLog ***
2018-xx-xx Sudakshina Das <sudi....@arm.com>
* gcc.target/aarch64/bti-1.c: New test.
* gcc.target/aarch64/bti-2.c: New test.
* lib/target-supports.exp
(check_effective_target_aarch64_bti_hw): Add new check for
BTI hw.
