[PATCH] Check _PAGE_RW and _PAGE_PRESENT on kernel addresses.

[Scott Wood]

On Wed, Aug 22, 2007 at 01:52:49PM +1000, Paul Mackerras wrote:
> Scott Wood writes:
> 
> > Previously, the TLB miss handlers assumed that pages above KERNELBASE are
> > always present and read/write.  This assumption is false in the case of
> > CONFIG_DEBUG_PAGEALLOC.
> 
> >  	blt+	112f
> > +	mfspr	r2,SPRN_SRR1		/* and MSR_PR bit from SRR1 */
> > +	rlwinm	r1,r2,32-12,29,29	/* shift MSR_PR to _PAGE_USER posn */
> >  	lis	r2,swapper_pg_dir at ha	/* if kernel address, use */
> >  	addi	r2,r2,swapper_pg_dir at l	/* kernel page table */
> > -	mfspr	r1,SPRN_SRR1		/* and MSR_PR bit from SRR1 */
> > -	rlwinm	r1,r1,32-12,29,29	/* shift MSR_PR to _PAGE_USER posn */
> 
> I don't see that just moving those two lines up changes anything.  If
> you turned the rlwinm into an rlwimi (as you did in the DataStoreTLBMiss
> case) then it might make more sense.  Is this just an oversight?

Sorry, rlwimi was what I meant...

The data store path was what I found the problem and tested with, the
others were an apparently botched replication to the other handlers.

-Scott