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>
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@ -86,6 +86,11 @@ static __always_inline bool memory_is_poisoned_2(unsigned long addr)
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if (memory_is_poisoned_1(addr + 1))
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return true;
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/*
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* If single shadow byte covers 2-byte access, we don't
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* need to do anything more. Otherwise, test the first
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* shadow byte.
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*/
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if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
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return false;
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@ -103,6 +108,11 @@ static __always_inline bool memory_is_poisoned_4(unsigned long addr)
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if (memory_is_poisoned_1(addr + 3))
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return true;
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/*
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* If single shadow byte covers 4-byte access, we don't
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* need to do anything more. Otherwise, test the first
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* shadow byte.
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*/
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if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
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return false;
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@ -120,7 +130,12 @@ static __always_inline bool memory_is_poisoned_8(unsigned long addr)
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if (memory_is_poisoned_1(addr + 7))
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return true;
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if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7))
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/*
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* If single shadow byte covers 8-byte access, we don't
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* need to do anything more. Otherwise, test the first
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* shadow byte.
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*/
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if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
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return false;
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return unlikely(*(u8 *)shadow_addr);
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@ -139,7 +154,12 @@ static __always_inline bool memory_is_poisoned_16(unsigned long addr)
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if (unlikely(shadow_first_bytes))
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return true;
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if (likely(IS_ALIGNED(addr, 8)))
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/*
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* If two shadow bytes covers 16-byte access, we don't
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* need to do anything more. Otherwise, test the last
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* shadow byte.
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*/
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if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
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return false;
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return memory_is_poisoned_1(addr + 15);
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