Re: [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64

Peter Zijlstra
2018-11-29T17:15:53Z

On Thu, Nov 29, 2018 at 08:59:31AM -0800, Andy Lutomirski wrote:

> If you make it conditional on CPL, do it for 32-bit as well, add
> comments,

> and convince yourself that there isn’t a better solution
> (like pointing IP at a stub that retpolines to the target by reading
> the function pointer, a la the unoptimizable version), then okay, I
> guess, with only a small amount of grumbling.

Right; so we _could_ grow the trampoline with a retpoline indirect call
and ret. It just makes the trampoline a whole lot bigger, but it could
work.