On Thu, 3 Dec 2015, Dave Hansen wrote: > > From: Dave Hansen <[email protected]> > > We want to modify the Protection Key rights inside the kernel, so > we need to change PKRU's contents. But, if we do a plain > 'wrpkru', when we return to userspace we might do an XRSTOR and > wipe out the kernel's 'wrpkru'. So, we need to go after PKRU in > the xsave buffer. > > We do this by: > 1. Ensuring that we have the XSAVE registers (fpregs) in the > kernel FPU buffer (fpstate) > 2. Looking up the location of a given state in the buffer > 3. Filling in the stat > 4. Ensuring that the hardware knows that state is present there > (basically that the 'init optimization' is not in place). > 5. Copying the newly-modified state back to the registers if > necessary. > > Signed-off-by: Dave Hansen <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
