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authorXishi Qiu <qiuxishi@huawei.com>2015-11-05 18:51:21 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-05 19:34:48 -0800
commit10f702627e139e21465f4c9d44f63527bbca163c (patch)
tree706cd924235c129fcf30bf766c038025fd227525
parente0d57714394f5e2ce4e2f9bbebf48e3c7a7fd3be (diff)
kasan: use IS_ALIGNED in memory_is_poisoned_8()
Use IS_ALIGNED() to determine whether the shadow span two bytes. It generates less code and more readable. Also add some comments in shadow check functions. Signed-off-by: Xishi Qiu <qiuxishi@huawei.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andrey Konovalov <adech.fo@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/kasan/kasan.c24
1 files changed, 22 insertions, 2 deletions
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 2b21ccd55cd4..d41b21bce6a0 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -86,6 +86,11 @@ static __always_inline bool memory_is_poisoned_2(unsigned long addr)
if (memory_is_poisoned_1(addr + 1))
return true;
+ /*
+ * If single shadow byte covers 2-byte access, we don't
+ * need to do anything more. Otherwise, test the first
+ * shadow byte.
+ */
if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
return false;
@@ -103,6 +108,11 @@ static __always_inline bool memory_is_poisoned_4(unsigned long addr)
if (memory_is_poisoned_1(addr + 3))
return true;
+ /*
+ * If single shadow byte covers 4-byte access, we don't
+ * need to do anything more. Otherwise, test the first
+ * shadow byte.
+ */
if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
return false;
@@ -120,7 +130,12 @@ static __always_inline bool memory_is_poisoned_8(unsigned long addr)
if (memory_is_poisoned_1(addr + 7))
return true;
- if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7))
+ /*
+ * If single shadow byte covers 8-byte access, we don't
+ * need to do anything more. Otherwise, test the first
+ * shadow byte.
+ */
+ if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
return false;
return unlikely(*(u8 *)shadow_addr);
@@ -139,7 +154,12 @@ static __always_inline bool memory_is_poisoned_16(unsigned long addr)
if (unlikely(shadow_first_bytes))
return true;
- if (likely(IS_ALIGNED(addr, 8)))
+ /*
+ * If two shadow bytes covers 16-byte access, we don't
+ * need to do anything more. Otherwise, test the last
+ * shadow byte.
+ */
+ if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
return false;
return memory_is_poisoned_1(addr + 15);