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

[Peter Zijlstra]

On Wed, May 31, 2017 at 06:17:16AM -0700, Kees Cook wrote:
> 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?

IIRC 6+