Re: [Xen-devel] [PATCH v8 01/17] x86: Support compiling with indirect branch thunks

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Sun, Jan 14, 2018 at 08:48:26PM +0100, David Woodhouse wrote:
> On Fri, 2018-01-12 at 18:00 +0000, Andrew Cooper wrote:
> > 
> > +.macro IND_THUNK_RETPOLINE reg:req
> > +        call 2f
> > +1:
> 
> Linux and GCC have now settled on 'pause;lfence;jmp' here.

What is the benefit of the 'pause' in that?
> 
> > +        lfence
> > +        jmp 1b
> > +2:
> > +        mov %\reg, (%rsp)
> > +        ret
> > +.endm
> > +



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