Re: [PATCH v3 01/13] x86/retpoline: Add initial retpoline support

[Linus Torvalds]

On Thu, Jan 4, 2018 at 10:17 AM, Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> Clearly Paul's approach to retpoline without lfence is faster.
> I'm guessing it wasn't shared with amazon/intel until now and
> this set of patches going to adopt it, right?
>
> Paul, could you share a link to a set of alternative gcc patches
> that do retpoline similar to llvm diff ?

What is the alternative approach? Is it literally just doing a

      call 1f
1:    mov real_target,(%rsp)
       ret

on the assumption that the "ret" will always just predict to that "1"
due to the call stack?

                Linus