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.biesheu...@linaro.org>
Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Marc Zyngier <marc.zyng...@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poul...@arm.com>
---
Changes since V2:
- Add comments around the macros
- Change ARM64_HW_PGTABLE_LEVEL_SHIFT to accept pagetable level as
described by ARM ARM
---
arch/arm64/include/asm/pgtable-hwdef.h | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h
b/arch/arm64/include/asm/pgtable-hwdef.h
index 95c1ec0..c6194ab 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -16,13 +16,31 @@
#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))
+ *
+ * We cannot include linux/kernel.h which defines DIV_ROUND_UP here
+ * due to build issues. So we use the following magic formula.
+ */
+#define ARM64_HW_PGTABLE_LEVELS(va_bits) (((va_bits) - 4) / (PAGE_SHIFT - 3))
+
+/*
+ * Size mapped by an entry at level n
+ * We map PAGE_SHIFT - 3 at all levels, except the PAGE_SHIFT bits at the last
level
+ */
+#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 +50,7 @@
* 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 +60,8 @@
* 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(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))
--
1.7.9.5
--
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