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SubjectRe: [v2 PATCH 2/2] powerpc/8xx: use _PAGE_RO instead of _PAGE_RW
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On Wed, 2014-12-17 at 10:14 +0100, Christophe Leroy wrote:
> On powerpc 8xx, in TLB entries, 0x400 bit is set to 1 for read-only pages
> and is set to 0 for RW pages. So we should use _PAGE_RO instead of _PAGE_RW
>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>
> ---
> v2 is a complete rework compared to v1
>
> arch/powerpc/include/asm/pte-8xx.h | 7 +++----
> arch/powerpc/kernel/head_8xx.S | 3 ---
> 2 files changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/pte-8xx.h b/arch/powerpc/include/asm/pte-8xx.h
> index daa4616..4f5583e 100644
> --- a/arch/powerpc/include/asm/pte-8xx.h
> +++ b/arch/powerpc/include/asm/pte-8xx.h
> @@ -46,7 +46,7 @@
> * require a TLB exception handler change. It is assumed unused bits
> * are always zero.
> */
> -#define _PAGE_RW 0x0400 /* lsb PP bits, inverted in HW */
> +#define _PAGE_RO 0x0400 /* lsb PP bits */

It looks like pte_update() needs to be updated to match.

> #define _PAGE_USER 0x0800 /* msb PP bits */
> /* set when neither _PAGE_USER nor _PAGE_RW are set */

Also update this comment.

> #define _PAGE_KNLRO 0x0200
> @@ -62,9 +62,8 @@
> #define PTE_ATOMIC_UPDATES 1
>
> /* We need to add _PAGE_SHARED to kernel pages */
> -#define _PAGE_KERNEL_RO (_PAGE_SHARED | _PAGE_KNLRO)
> -#define _PAGE_KERNEL_ROX (_PAGE_EXEC | _PAGE_KNLRO)
> -#define _PAGE_KERNEL_RW (_PAGE_DIRTY | _PAGE_RW | _PAGE_HWWRITE)
> +#define _PAGE_KERNEL_RO (_PAGE_SHARED | _PAGE_RO | _PAGE_KNLRO)
> +#define _PAGE_KERNEL_ROX (_PAGE_EXEC | _PAGE_RO | _PAGE_KNLRO)
>
> #endif /* __KERNEL__ */
> #endif /* _ASM_POWERPC_PTE_8xx_H */

Where did _PAGE_KERNEL_RW go?

-Scott




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