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Date: Fri, 19 Apr 2002 14:35:57 -0700 (PDT)
Subject: Re: SSE related security hole
From: "H. Peter Anvin" <hpa@zytor.com>
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>>
>> 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.



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