diff options
| author | Xishi Qiu <qiuxishi@huawei.com> | 2015-11-05 18:51:21 -0800 |
|---|---|---|
| committer | Alex Shi <alex.shi@linaro.org> | 2016-04-11 16:10:25 +0800 |
| commit | 9060ab15af2fc9fda3e0eff7f322ceca62982109 (patch) | |
| tree | b7f3355084886494530ca5c25a2bbaefceb9fe69 | |
| parent | 9c937a3526e99b33ee5b9e693aa0272bccbd04d0 (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>
(cherry picked from commit 10f702627e139e21465f4c9d44f63527bbca163c)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
| -rw-r--r-- | mm/kasan/kasan.c | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c index 1a665070fbe9..7f97c85e0d44 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); |