[PATCH] powerpc/mm: Fix _PAGE_COHERENT support on classic ppc32 HW

[Becky Bruce]

On Feb 10, 2009, at 2:57 PM, Kumar Gala wrote:

> The following commit:
>
> commit 64b3d0e8122b422e879b23d42f9e0e8efbbf9744
> Author: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> Date:   Thu Dec 18 19:13:51 2008 +0000
>
>    powerpc/mm: Rework usage of _PAGE_COHERENT/NO_CACHE/GUARDED
>
> broke setting of the _PAGE_COHERENT bit in the PPC HW PTE.  Since we  
> now
> actually set _PAGE_COHERENT in the Linux PTE we shouldn't be  
> clearing it
> out before we propogate it to the PPC HW PTE.
>
> Reported-by: Martyn Welch <martyn.welch at gefanuc.com>
> Signed-off-by: Kumar Gala <galak at kernel.crashing.org>

I've booted 8641 dual-core and run LTP to completion with an expected  
number of fails.  So....

Acked-by: Becky Bruce <beckyb at kernel.crashing.org>

-B

>
> ---
> arch/powerpc/mm/hash_low_32.S |    2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/powerpc/mm/hash_low_32.S b/arch/powerpc/mm/ 
> hash_low_32.S
> index 67850ec..14af8ce 100644
> --- a/arch/powerpc/mm/hash_low_32.S
> +++ b/arch/powerpc/mm/hash_low_32.S
> @@ -320,7 +320,7 @@ _GLOBAL(create_hpte)
> 	and	r8,r8,r0		/* writable if _RW & _DIRTY */
> 	rlwimi	r5,r5,32-1,30,30	/* _PAGE_USER -> PP msb */
> 	rlwimi	r5,r5,32-2,31,31	/* _PAGE_USER -> PP lsb */
> -	ori	r8,r8,0xe14		/* clear out reserved bits and M */
> +	ori	r8,r8,0xe04		/* clear out reserved bits */
> 	andc	r8,r5,r8		/* PP = user? (rw&dirty? 2: 3): 0 */
> BEGIN_FTR_SECTION
> 	rlwinm	r8,r8,0,~_PAGE_COHERENT	/* clear M (coherence not required) */
> -- 
> 1.5.6.6