Re: [PATCH] x86/speculation: Use AMD specific retpoline for inline asm on AMD

[Zhenzhong Duan]

On 2018/9/18 18:59, Peter Zijlstra wrote:
> On Tue, Sep 18, 2018 at 06:31:07PM +0800, Zhenzhong Duan wrote:
> > On 2018/9/18 17:50, Peter Zijlstra wrote:
> > > On Mon, Sep 17, 2018 at 10:17:30PM -0700, Zhenzhong Duan wrote:
> > > > -#elif defined(CONFIG_X86_32) && defined(CONFIG_RETPOLINE)
> > > > +#elif defined(CONFIG_RETPOLINE)
> > >
> > > This doesn't make any sense..
> > This change is used for x86_64 to have minimal Retpoline support when
> > CONFIG_RETPOLINE is defined but RETPOLINE isn't defined, or I missed
> > something?
>
> No it doesn't.
>
> #if defined(X86_64) && defined(RETPOLINE)
>
>   /* x86_64 retpoline goes here */
>
> #elif defined(RETPOLINE)
>
>   /* !x86_64 retpoline goes here */
>
> #else
>
>   /* !retpoline goes here
>
> #endif

Sorry, but I am confused.
So where is 'if defined(x86_64) && !defined(RETPOLINE) && 
defined(CONFIG_RETPOLINE)' go?
In original code, it will go to "call *%[thunk_target]\n" while
we have set SPECTRE_V2_RETPOLINE_MINIMAL or 
SPECTRE_V2_RETPOLINE_MINIMAL_AMD. Is this expected?

Thanks
Zhenzhong