Re: [PATCH] Re: SSE related security hole

H. Peter Anvin
2002-04-23T20:06:01Z

Linus Torvalds wrote:
>
> On Sat, 20 Apr 2002, Andrea Arcangeli wrote:
>
>>I mean, if they change the registers layout, and so if they require a
>>different empty FPU state, they must as well add yet another bitflag to
>>enable SSE3, if they don't the chip isn't backwards compatible.
>
>
> I have unofficial confirmation from Intel that the way to architecturally
> initialize the FPU state is indeed something like
>
> memset(&fxsave, 0, sizeof(struct i387_fxsave_struct));
> fxsave.cwd = 0x37f;
> fxsave.mxcsr = 0x1f80;
> fxrstor(&fxsave);
>
> and the person in question is trying to make sure this is documented so
> that we won't be bitten by this in the future.
>

Great!

-hpa