Re: [PATCH v3 4/9] x86: alternatives: macrofy locks for better inlining

[Peter Zijlstra]

On Sun, Jun 10, 2018 at 07:19:06AM -0700, Nadav Amit wrote:
>  #ifdef CONFIG_SMP
> +.macro LOCK_PREFIX_HERE
>  	.pushsection .smp_locks,"a"
>  	.balign 4
> +	.long 671f - .		# offset
>  	.popsection
> +671:
> +.endm
> +
> +.macro LOCK_PREFIX insn:vararg
> +	LOCK_PREFIX_HERE
> +	lock \insn
> +.endm

Hurmph, the only reason we need to preserve that LOCK_PREFIX_HERE thing
is arch_cmpxchg64 in cmpxchg_32.h. Is there really no other way we can
write that one?

I suppose the problem with using LOCK_PREFIX inside the alternative is
that the .smp_locks fixup address gets computed wrong (inside the
alternative_text section instead of in the regular text)?

Oh well..