Hi Suzuki, On Tue, Sep 15, 2015 at 04:41:12PM +0100, Suzuki K. Poulose wrote: > From: "Suzuki K. Poulose" <suzuki.poulose@xxxxxxx> > > Introduce helpers for finding the number of page table > levels required for a given VA width, shift for a particular > page table level. > > Convert the existing users to the new helpers. More users > to follow. > > Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > Cc: Mark Rutland <mark.rutland@xxxxxxx> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx> > Cc: Will Deacon <will.deacon@xxxxxxx> > Signed-off-by: Suzuki K. Poulose <suzuki.poulose@xxxxxxx> > Reviewed-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > Tested-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > --- > arch/arm64/include/asm/pgtable-hwdef.h | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h > index 24154b0..ce18389 100644 > --- a/arch/arm64/include/asm/pgtable-hwdef.h > +++ b/arch/arm64/include/asm/pgtable-hwdef.h > @@ -16,13 +16,21 @@ > #ifndef __ASM_PGTABLE_HWDEF_H > #define __ASM_PGTABLE_HWDEF_H > > +/* > + * Number of page-table levels required to address 'va_bits' wide > + * address, without section mapping > + */ > +#define ARM64_HW_PGTABLE_LEVELS(va_bits) (((va_bits) - 4) / (PAGE_SHIFT - 3)) I don't understand the '(va_bits) - 4' here, can you explain it (and add a comment to that effect) ? > +#define ARM64_HW_PGTABLE_LEVEL_SHIFT(level) \ > + ((PAGE_SHIFT - 3) * (level) + 3) > + While this change is clearly correct, if you can explain the math here in a comment as well, that would be helpful. Thanks, -Christoffer > #define PTRS_PER_PTE (1 << (PAGE_SHIFT - 3)) > > /* > * PMD_SHIFT determines the size a level 2 page table entry can map. > */ > #if CONFIG_PGTABLE_LEVELS > 2 > -#define PMD_SHIFT ((PAGE_SHIFT - 3) * 2 + 3) > +#define PMD_SHIFT ARM64_HW_PGTABLE_LEVEL_SHIFT(2) > #define PMD_SIZE (_AC(1, UL) << PMD_SHIFT) > #define PMD_MASK (~(PMD_SIZE-1)) > #define PTRS_PER_PMD PTRS_PER_PTE > @@ -32,7 +40,7 @@ > * PUD_SHIFT determines the size a level 1 page table entry can map. > */ > #if CONFIG_PGTABLE_LEVELS > 3 > -#define PUD_SHIFT ((PAGE_SHIFT - 3) * 3 + 3) > +#define PUD_SHIFT ARM64_HW_PGTABLE_LEVEL_SHIFT(3) > #define PUD_SIZE (_AC(1, UL) << PUD_SHIFT) > #define PUD_MASK (~(PUD_SIZE-1)) > #define PTRS_PER_PUD PTRS_PER_PTE > @@ -42,7 +50,8 @@ > * PGDIR_SHIFT determines the size a top-level page table entry can map > * (depending on the configuration, this level can be 0, 1 or 2). > */ > -#define PGDIR_SHIFT ((PAGE_SHIFT - 3) * CONFIG_PGTABLE_LEVELS + 3) > +#define PGDIR_SHIFT \ > + ARM64_HW_PGTABLE_LEVEL_SHIFT(CONFIG_PGTABLE_LEVELS) > #define PGDIR_SIZE (_AC(1, UL) << PGDIR_SHIFT) > #define PGDIR_MASK (~(PGDIR_SIZE-1)) > #define PTRS_PER_PGD (1 << (VA_BITS - PGDIR_SHIFT)) > -- > 1.7.9.5 > > _______________________________________________ > kvmarm mailing list > kvmarm@xxxxxxxxxxxxxxxxxxxxx > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
