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

[Peter Zijlstra]

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.