kasan, arm64: use ARCH_SLAB_MINALIGN instead of manual aligning

Instead of changing cache->align to be aligned to KASAN_SHADOW_SCALE_SIZE
in kasan_cache_create() we can reuse the ARCH_SLAB_MINALIGN macro.

Link: http://lkml.kernel.org/r/52ddd881916bcc153a9924c154daacde78522227.1546540962.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Suggested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/arm64/include/asm/cache.h

@@ -58,6 +58,12 @@
  */
 #define ARCH_DMA_MINALIGN	(128)
 
+#ifdef CONFIG_KASAN_SW_TAGS
+#define ARCH_SLAB_MINALIGN	(1ULL << KASAN_SHADOW_SCALE_SHIFT)
+#else
+#define ARCH_SLAB_MINALIGN	__alignof__(unsigned long long)
+#endif
+
 #ifndef __ASSEMBLY__
 
 #include <linux/bitops.h>

mm/kasan/common.c

@@ -298,8 +298,6 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
 		return;
 	}
 
-	cache->align = round_up(cache->align, KASAN_SHADOW_SCALE_SIZE);
-
 	*flags |= SLAB_KASAN;
 }