Re: [PATCH 1/1] x86/fpu: math_state_restore() should not blindly disable irqs

From: Andy Lutomirski
Date: Sun Mar 08 2015 - 10:39:01 EST

On Sun, Mar 8, 2015 at 6:59 AM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> There's another problem, though: We don't have a real stack pointer
> just after syscall and just before sysexit, and therefore we *must*
> use IST for anything that can happen while we still have
> user-controlled rsp. That includes #DB, #NM, and #MC.

I think I faked myself out here. Why do #DB and #BP use IST? We
could remove a decent (large?) amount of crud if we changed that.

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