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SubjectRe: [PATCH v2 06/22] ARM: LPAE: use signed arithmetic for mask definitions
On Fri, 10 Aug 2012, Cyril Chemparathy wrote:

> This patch applies to PAGE_MASK, PMD_MASK, and PGDIR_MASK, where forcing
> unsigned long math truncates the mask at the 32-bits. This clearly does bad
> things on PAE systems.
>
> This patch fixes this problem by defining these masks as signed quantities.
> We then rely on sign extension to do the right thing.
>
> Signed-off-by: Cyril Chemparathy <cyril@ti.com>
> Signed-off-by: Vitaly Andrianov <vitalya@ti.com>

Reviewed-by: Nicolas Pitre <nico@linaro.org>

> ---
> arch/arm/include/asm/page.h | 2 +-
> arch/arm/include/asm/pgtable-3level.h | 6 +++---
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h
> index ecf9019..1e0fe08 100644
> --- a/arch/arm/include/asm/page.h
> +++ b/arch/arm/include/asm/page.h
> @@ -13,7 +13,7 @@
> /* PAGE_SHIFT determines the page size */
> #define PAGE_SHIFT 12
> #define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT)
> -#define PAGE_MASK (~(PAGE_SIZE-1))
> +#define PAGE_MASK (~((1 << PAGE_SHIFT) - 1))
>
> #ifndef __ASSEMBLY__
>
> diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h
> index b249035..ae39d11 100644
> --- a/arch/arm/include/asm/pgtable-3level.h
> +++ b/arch/arm/include/asm/pgtable-3level.h
> @@ -48,16 +48,16 @@
> #define PMD_SHIFT 21
>
> #define PMD_SIZE (1UL << PMD_SHIFT)
> -#define PMD_MASK (~(PMD_SIZE-1))
> +#define PMD_MASK (~((1 << PMD_SHIFT) - 1))
> #define PGDIR_SIZE (1UL << PGDIR_SHIFT)
> -#define PGDIR_MASK (~(PGDIR_SIZE-1))
> +#define PGDIR_MASK (~((1 << PGDIR_SHIFT) - 1))
>
> /*
> * section address mask and size definitions.
> */
> #define SECTION_SHIFT 21
> #define SECTION_SIZE (1UL << SECTION_SHIFT)
> -#define SECTION_MASK (~(SECTION_SIZE-1))
> +#define SECTION_MASK (~((1 << SECTION_SHIFT) - 1))
>
> #define USER_PTRS_PER_PGD (PAGE_OFFSET / PGDIR_SIZE)
>
> --
> 1.7.9.5
>


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