PING^2: [PATCH] i386: Add __x86_indirect_thunk_nt_reg for -fcf-protection -mcet

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Feb 8, 2018 at 10:09 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Fri, Feb 2, 2018 at 8:54 AM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>> nocf_check attribute can be used with -fcf-protection -mcet to disable
>> control-flow check by adding NOTRACK prefix before indirect branch.
>> When -mindirect-branch=thunk-extern -mindirect-branch-register is added,
>> indirect branch via register, "notrack call/jmp reg", is converted to
>>
>>     call/jmp __x86_indirect_thunk_nt_reg
>>
>> When running on machines with CET enabled, __x86_indirect_thunk_nt_reg
>> can be updated to
>>
>>     notrack jmp reg
>>
>> at run-time to restore NOTRACK prefix in the original indirect branch.
>>
>> Since we don't support -mindirect-branch=thunk-extern, CET and MPX at
>> the same time, -mindirect-branch=thunk-extern is disallowed with
>> -fcf-protection=branch and -fcheck-pointer-bounds.
>>
>> Tested on i686 and x86-64.  OK for trunk?
>>
>> Thanks.
>>
>> H.J.
>> ---
>> gcc/
>>
>>         PR target/84176
>>         * config/i386/i386.c (ix86_set_indirect_branch_type): Issue an
>>         error when -mindirect-branch=thunk-extern, -fcf-protection=branch
>>         and -fcheck-pointer-bounds are used together.
>>         (indirect_thunk_prefix): New enum.
>>         (indirect_thunk_need_prefix): New function.
>>         (indirect_thunk_name): Replace need_bnd_p with need_prefix.  Use
>>         "_nt" instead of "_bnd" for NOTRACK prefix.
>>         (output_indirect_thunk): Replace need_bnd_p with need_prefix.
>>         (output_indirect_thunk_function): Likewise.
>>         (): Likewise.
>>         (ix86_code_end): Update output_indirect_thunk_function calls.
>>         (ix86_output_indirect_branch_via_reg): Replace
>>         ix86_bnd_prefixed_insn_p with indirect_thunk_need_prefix.
>>         (ix86_output_indirect_branch_via_push): Likewise.
>>         (ix86_output_function_return): Likewise.
>>         * doc/invoke.texi: Document -mindirect-branch=thunk-extern is
>>         incompatible with -fcf-protection=branch and
>>         -fcheck-pointer-bounds.
>>
>> gcc/testsuite/
>>
>>         PR target/84176
>>         * gcc.target/i386/indirect-thunk-11.c: New test.
>>         * gcc.target/i386/indirect-thunk-12.c: Likewise.
>>         * gcc.target/i386/indirect-thunk-attr-12.c: Likewise.
>>         * gcc.target/i386/indirect-thunk-attr-13.c: Likewise.
>>         * gcc.target/i386/indirect-thunk-attr-14.c: Likewise.
>>         * gcc.target/i386/indirect-thunk-attr-15.c: Likewise.
>>         * gcc.target/i386/indirect-thunk-attr-16.c: Likewise.
>>         * gcc.target/i386/indirect-thunk-extern-10.c: Likewise.
>>         * gcc.target/i386/indirect-thunk-extern-8.c: Likewise.
>>         * gcc.target/i386/indirect-thunk-extern-9.c: Likewise.
>
> Hi Jan,
>
> Can you review it:
>
> https://gcc.gnu.org/ml/gcc-patches/2018-02/msg00113.html
>

Hi Jan,

Can you take a look?  I have more retpoline patches which
depend on this one.

Thanks.

-- 
H.J.