[PATCH] Check _PAGE_RW and _PAGE_PRESENT on kernel addresses.

[Paul Mackerras]

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?

Paul.