diff options
| author | Suzuki K. Poulose <suzuki.poulose@arm.com> | 2015-10-19 16:19:29 +0300 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2015-10-19 19:53:08 +0300 |
| commit | 686e783869d37935510b4d2c266948677be82665 (patch) | |
| tree | c172cadcb0556474062dbe772e0b4ed5c3bf23d4 /arch/arm64/include/asm/pgtable-hwdef.h | |
| parent | b433dce056d3814dc4b33e5a8a533d6401ffcfb0 (diff) | |
| download | linux-686e783869d37935510b4d2c266948677be82665.tar.xz | |
arm64: Introduce helpers for page table levels
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@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/pgtable-hwdef.h')
| -rw-r--r-- | arch/arm64/include/asm/pgtable-hwdef.h | 39 |
1 files changed, 36 insertions, 3 deletions
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h index 95c1ec04a9ed..d6739e836f7b 100644 --- a/arch/arm64/include/asm/pgtable-hwdef.h +++ b/arch/arm64/include/asm/pgtable-hwdef.h @@ -16,13 +16,46 @@ #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. We resolve the top (va_bits - PAGE_SHIFT) + * bits with (PAGE_SHIFT - 3) bits at each page table level. Hence: + * + * levels = DIV_ROUND_UP((va_bits - PAGE_SHIFT), (PAGE_SHIFT - 3)) + * + * where DIV_ROUND_UP(n, d) => (((n) + (d) - 1) / (d)) + * + * We cannot include linux/kernel.h which defines DIV_ROUND_UP here + * due to build issues. So we open code DIV_ROUND_UP here: + * + * ((((va_bits) - PAGE_SHIFT) + (PAGE_SHIFT - 3) - 1) / (PAGE_SHIFT - 3)) + * + * which gets simplified as : + */ +#define ARM64_HW_PGTABLE_LEVELS(va_bits) (((va_bits) - 4) / (PAGE_SHIFT - 3)) + +/* + * Size mapped by an entry at level n ( 0 <= n <= 3) + * We map (PAGE_SHIFT - 3) at all translation levels and PAGE_SHIFT bits + * in the final page. The maximum number of translation levels supported by + * the architecture is 4. Hence, starting at at level n, we have further + * ((4 - n) - 1) levels of translation excluding the offset within the page. + * So, the total number of bits mapped by an entry at level n is : + * + * ((4 - n) - 1) * (PAGE_SHIFT - 3) + PAGE_SHIFT + * + * Rearranging it a bit we get : + * (4 - n) * (PAGE_SHIFT - 3) + 3 + */ +#define ARM64_HW_PGTABLE_LEVEL_SHIFT(n) ((PAGE_SHIFT - 3) * (4 - (n)) + 3) + #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 +65,7 @@ * 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(1) #define PUD_SIZE (_AC(1, UL) << PUD_SHIFT) #define PUD_MASK (~(PUD_SIZE-1)) #define PTRS_PER_PUD PTRS_PER_PTE @@ -42,7 +75,7 @@ * 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(4 - 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)) |