Re: [RFC][PATCH 3/3] x86/entry, ORC: Teach objtool/unwind_orc about stack irq swizzles

From: Peter Zijlstra
Date: Fri May 08 2020 - 06:12:34 EST


On Thu, May 07, 2020 at 11:24:49PM +0200, Thomas Gleixner wrote:
> But over our IRC conversation I came up with a 3rd variant:
>
> For most of the vectors the indirect call overhead is just noise, so
> we can run them through the ASM switcher, but for the resched IPI
> we can just use a separate direct call stub in ASM.

Are we sure the rat-poison crap is noise for all the other system
vectors? I suppose it is for most since they'll do indirect calls
themselves anyway, right?

> I can live with that. I might have to pay up for Peter's headaches to
> teach objtool, but that's a different story. Let me check how many beers
> he owes me first ...

We're going to be so massively drunk if we ever settle that :-) For now
I'll just have to live with knowing more about the unwinders.