The patch titled
Subject: kasan: use IS_ALIGNED in memory_is_poisoned_8()
has been added to the -mm tree. Its filename is
kasan-use-is_aligned-in-memory_is_poisoned_8.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kasan-use-is_aligned-in-memory_is_poisoned_8.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kasan-use-is_aligned-in-memory_is_poisoned_8.patch
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------------------------------------------------------
From: Xishi Qiu <qiuxishi@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx>
Acked-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Andrey Konovalov <adech.fo@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kasan/kasan.c | 24 ++++++++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)
diff -puN mm/kasan/kasan.c~kasan-use-is_aligned-in-memory_is_poisoned_8 mm/kasan/kasan.c
--- a/mm/kasan/kasan.c~kasan-use-is_aligned-in-memory_is_poisoned_8
+++ a/mm/kasan/kasan.c
@@ -86,6 +86,11 @@ static __always_inline bool memory_is_po
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_po
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_po
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_po
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);
_
Patches currently in -mm which might be from qiuxishi@xxxxxxxxxx are
kasan-fix-last-shadow-judgement-in-memory_is_poisoned_16.patch
kasan-use-is_aligned-in-memory_is_poisoned_8.patch
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