Re: SSE related security hole

Andi Kleen
2002-04-19T21:42:10Z

On Fri, Apr 19, 2002 at 02:35:57PM -0700, H. Peter Anvin wrote:
> >>
> >> Ummm...last I knew, fxrstor is *expensive*. The fninit/xor regs setup
> >> is likely *very* much faster. Someone should check this before we
> >> sacrifice 100 cycles needlessly or something.
> >
> > most probably yes, fxrestor needs to read ram, pxor also takes some
> > icache and bytecode ram but it sounds like it will be faster.
> >
> > Maybe we could also interleave the pxor with the xorps, since they uses
> > different parts of the cpu, Honza?
> >
>
> You almost certainly should. The reason I suggested FXRSTOR is that it
> would initialize the entire FPU, including any state that future
> processors may add, thus reducing the likelihood of any funnies in the
> future.

That's also why I like it.

-Andi