RE: [PATCH v2 3/4] x86, head_32/64.S: Enable SMEP

[Yu, Fenghua]

> -----Original Message-----
> From: H. Peter Anvin [mailto:hpa@xxxxxxxxx]
> Sent: Tuesday, May 17, 2011 4:13 PM
> To: Yu, Fenghua
> Cc: Matthew Garrett; Ingo Molnar; Thomas Gleixner; Mallick, Asit K;
> Linus Torvalds; Avi Kivity; Arjan van de Ven; Andrew Morton; Andi
> Kleen; linux-kernel
> Subject: Re: [PATCH v2 3/4] x86, head_32/64.S: Enable SMEP
> 
> On 05/17/2011 04:08 PM, Yu, Fenghua wrote:
> >>
> >> Are EFI runtime service pages currently set up appropriately?
> >
> > They are not set up yet. efi init is called after this.
> >
> > But at this time there is no user space code yet. So there is no SMEP
> violation chance until later when any user space page table is setup.
> >
> 
> Are EFI runtime pages set up with U=0?  I would argue it is a bug if
> they aren't, but we want to make sure that there isn't such a bug.
> 
> 	-hpa

The runtime services are ioremapped. So they should be U=0.

Thanks.

-Fenghua
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