[patch] powerpc: implement pte_special for 64K pages

[Benjamin Herrenschmidt]

On Thu, 2008-07-17 at 12:44 +0200, Nick Piggin wrote:
> This can be folded into powerpc-implement-pte_special.patch
> 
> --
> Ben has now freed up a pte bit on 64k pages. Use it for special pte bit.
> 
> Signed-off-by: Nick Piggin <npiggin at suse.de>
> ---

Ack.

Andrew, will you merge this or do you want me to ?

Cheers,
Ben.

> Index: linux-2.6/include/asm-powerpc/pgtable-64k.h
> ===================================================================
> --- linux-2.6.orig/include/asm-powerpc/pgtable-64k.h	2008-07-17 18:53:03.000000000 +1000
> +++ linux-2.6/include/asm-powerpc/pgtable-64k.h	2008-07-17 20:30:06.000000000 +1000
> @@ -70,11 +70,12 @@
>  #define PGDIR_MASK	(~(PGDIR_SIZE-1))
>  
>  /* Additional PTE bits (don't change without checking asm in hash_low.S) */
> +#define __HAVE_ARCH_PTE_SPECIAL
> +#define _PAGE_SPECIAL	0x00000400 /* software: special page */
>  #define _PAGE_HPTE_SUB	0x0ffff000 /* combo only: sub pages HPTE bits */
>  #define _PAGE_HPTE_SUB0	0x08000000 /* combo only: first sub page */
>  #define _PAGE_COMBO	0x10000000 /* this is a combo 4k page */
>  #define _PAGE_4K_PFN	0x20000000 /* PFN is for a single 4k page */
> -#define _PAGE_SPECIAL	0x0	   /* don't have enough room for this yet */
>  
>  /* For 64K page, we don't have a separate _PAGE_HASHPTE bit. Instead,
>   * we set that to be the whole sub-bits mask. The C code will only