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authorCatalin Marinas <catalin.marinas@arm.com>2014-10-10 15:37:28 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2014-10-20 17:47:02 +0100
commit2a0b5c0d19298cad54573682321b5fe015fa5a0d (patch)
treed1b64ac1f1ce289bb1184fa4563930a2be9519e8 /arch/arm64/mm
parent04f905a9569ca2b6964a35563f135fabbb2470bc (diff)
downloadlinux-2a0b5c0d19298cad54573682321b5fe015fa5a0d.tar.bz2
arm64: Align less than PAGE_SIZE pgds naturally
When the pgd size is smaller than PAGE_SIZE, pgd_alloc() uses kzalloc() to save space. However, this is not always naturally aligned as required by the architecture. This patch creates a kmem_cache for pgd allocations with the correct alignment. The current kernel configurations with 4K pages + 39-bit VA and 64K pages + 42-bit VA use a full page for the pgd and are not affected. The patch is required for 48-bit VA with 64K pages where the pgd is 512 bytes. Reported-by: Christoffer Dall <christoffer.dall@linaro.org> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/mm')
-rw-r--r--arch/arm64/mm/pgd.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/arch/arm64/mm/pgd.c b/arch/arm64/mm/pgd.c
index 62c6101df260..6682b361d3ac 100644
--- a/arch/arm64/mm/pgd.c
+++ b/arch/arm64/mm/pgd.c
@@ -30,12 +30,14 @@
#define PGD_SIZE (PTRS_PER_PGD * sizeof(pgd_t))
+static struct kmem_cache *pgd_cache;
+
pgd_t *pgd_alloc(struct mm_struct *mm)
{
if (PGD_SIZE == PAGE_SIZE)
return (pgd_t *)get_zeroed_page(GFP_KERNEL);
else
- return kzalloc(PGD_SIZE, GFP_KERNEL);
+ return kmem_cache_zalloc(pgd_cache, GFP_KERNEL);
}
void pgd_free(struct mm_struct *mm, pgd_t *pgd)
@@ -43,5 +45,17 @@ void pgd_free(struct mm_struct *mm, pgd_t *pgd)
if (PGD_SIZE == PAGE_SIZE)
free_page((unsigned long)pgd);
else
- kfree(pgd);
+ kmem_cache_free(pgd_cache, pgd);
+}
+
+static int __init pgd_cache_init(void)
+{
+ /*
+ * Naturally aligned pgds required by the architecture.
+ */
+ if (PGD_SIZE != PAGE_SIZE)
+ pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
+ SLAB_PANIC, NULL);
+ return 0;
}
+core_initcall(pgd_cache_init);