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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>
This commit is contained in:
Suzuki K. Poulose 2015-10-19 14:19:29 +01:00 committed by Catalin Marinas
parent b433dce056
commit 686e783869
1 changed files with 36 additions and 3 deletions
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39
arch/arm64/include/asm/pgtable-hwdef.h
View File

@ -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))