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arm64: choose memstart_addr based on minimum sparsemem section alignment 

This redefines ARM64_MEMSTART_ALIGN in terms of the minimal alignment
required by sparsemem vmemmap. This comes down to using 1 GB for all
translation granules if CONFIG_SPARSEMEM_VMEMMAP is enabled.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Ard Biesheuvel 2016-03-30 14:25:47 +02:00 committed by Will Deacon
parent 2958987f5d
commit 06e9bf2fd9
1 changed files with 18 additions and 3 deletions
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21
arch/arm64/include/asm/kernel-pgtable.h
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@ -19,6 +19,7 @@
#ifndef __ASM_KERNEL_PGTABLE_H
#define __ASM_KERNEL_PGTABLE_H
#include <asm/sparsemem.h>
/*
* The linear mapping and the start of memory are both 2M aligned (per
@ -86,10 +87,24 @@
* (64k granule), or a multiple that can be mapped using contiguous bits
* in the page tables: 32 * PMD_SIZE (16k granule)
*/
#ifdef CONFIG_ARM64_64K_PAGES
#define ARM64_MEMSTART_ALIGN SZ_512M
#if defined(CONFIG_ARM64_4K_PAGES)
#define ARM64_MEMSTART_SHIFT PUD_SHIFT
#elif defined(CONFIG_ARM64_16K_PAGES)
#define ARM64_MEMSTART_SHIFT (PMD_SHIFT + 5)
#else
#define ARM64_MEMSTART_ALIGN SZ_1G
#define ARM64_MEMSTART_SHIFT PMD_SHIFT
#endif
/*
* sparsemem vmemmap imposes an additional requirement on the alignment of
* memstart_addr, due to the fact that the base of the vmemmap region
* has a direct correspondence, and needs to appear sufficiently aligned
* in the virtual address space.
*/
#if defined(CONFIG_SPARSEMEM_VMEMMAP) && ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
#define ARM64_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS)
#else
#define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT)
#endif
#endif /* __ASM_KERNEL_PGTABLE_H */