Re: [PATCH v5 2/3] x86/asm: Add suffix macro for GEN_*_RMWcc()

[Kees Cook]

On Wed, May 31, 2017 at 4:13 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Tue, May 30, 2017 at 02:39:51PM -0700, Kees Cook wrote:
>> The coming x86 refcount protection needs to be able to add trailing
>> instructions to the GEN_*_RMWcc() operations. This extracts the
>> difference between the goto/non-goto cases so the helper macros
>> can be defined outside the #ifdef cases. Additionally adds argument
>> naming to the resulting asm for referencing from suffixed
>> instructions, and adds clobbers for "cc", and "cx" to let suffixes
>> use _ASM_CX, and retain any set flags.
>
> Another option is to simply require __GCC_ASM_FLAG_OUTPUT__ for the fast
> refcount stuff. That would result in simpler and more readable code.

What versions of GCC support that?

-Kees

-- 
Kees Cook
Pixel Security