On Mon, Feb 22, 2016 at 12:00:02PM -0800, Dave Hansen wrote:
> On 02/22/2016 11:00 AM, Yu-cheng Yu wrote:
> > + if (xsave->header.xfeatures & XFEATURE_MASK_SUPERVISOR)
> > + xsave->header.xfeatures = xfeatures | XFEATURE_MASK_SUPERVISOR;
> > + else
> > + xsave->header.xfeatures = xfeatures;
>
> This is dangerous. It says, "if any supervisor feature bit is set, then
> set *ALL* of the known bits". There's no way that can work.
>
> Don't you just want to or in the new bits that were in the passed-in
> 'xfeatures':
>
> xsave->header.xfeatures |= xfeatures;
>
> 'xfeatures' is known not to contain any supervisor bits.
>
It should have been:
xsave->header.xfeatures = xfeatures |
(xsave->header.xfeatures & XFEATURE_MASK_SUPERVISOR);
I'll fix it.
--Yu-cheng
