Re: [PATCH] x86/cpufeature: guard asm_volatile_goto usage with CC_HAVE_ASM_GOTO

From: Yonghong Song
Date: Sat Apr 14 2018 - 16:32:00 EST




On 4/14/18 3:11 AM, Peter Zijlstra wrote:
On Fri, Apr 13, 2018 at 01:42:14PM -0700, Alexei Starovoitov wrote:
On 4/13/18 11:19 AM, Peter Zijlstra wrote:
On Tue, Apr 10, 2018 at 02:28:04PM -0700, Alexei Starovoitov wrote:
Instead of
#ifdef CC_HAVE_ASM_GOTO
we can replace it with
#ifndef __BPF__
or some other name,

I would prefer the BPF specific hack; otherwise we might be encouraging
people to build the kernel proper without asm-goto.


I don't understand this concern.

The thing is; this will be a (temporary) BPF specific hack. Hiding it
behind something that looks 'normal' (CC_HAVE_ASM_GOTO) is just not
right.

This is a fair concern. I will use a different macro and send v2 soon.
Thanks.