On Fri, Sep 21, 2012 at 11:56:04AM -0400, 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 <cy...@ti.com> > Signed-off-by: Vitaly Andrianov <vita...@ti.com> > Reviewed-by: Nicolas Pitre <n...@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))
It's strange. Every other platform in the kernel, including those with PAE, manage to get away with defining PAGE_MASK as the original above (see asm-generic/pgtable.h) Why is ARM any different? Note that PAGE_MASK gets used at the moment on ARM for both virtual and physical addresses. x86 has PHYSICAL_PAGE_MASK for masking physical addresses. Maybe we should adopt the same approach? Whatever, I feel that we should not deviate from the established definitions across every other architecture. > > #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)) These masks are applied to a _virtual_ kernel address, not the physical addresses, Even with LPAE, the virtual address space is still 32-bit. So this is definitely wrong. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
