Messages in this thread | | | Date | Mon, 14 Sep 2015 09:17:43 +0800 | From | Xishi Qiu <> | Subject | Re: [PATCH] kasan: use IS_ALIGNED in memory_is_poisoned_8() |
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On 2015/9/12 6:47, Andrew Morton wrote:
> On Fri, 11 Sep 2015 10:02:29 +0800 Xishi Qiu <qiuxishi@huawei.com> wrote: > >> Use IS_ALIGNED() to determine whether the shadow span two bytes. >> It generates less code and more readable. >> > > Please cc Andrey Ryabinin on kasan patches.
Sorry, my mistake.
> >> --- a/mm/kasan/kasan.c >> +++ b/mm/kasan/kasan.c >> @@ -120,7 +120,7 @@ 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 (likely(IS_ALIGNED(addr, 8))) >> return false; > > Wouldn't IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE) be more appropriate? >
OK, I'll send V2.
> But I'm not really sure what the original code is trying to do. > > if ((addr + 7) & 7) >= 7) > > can only evaluate true if ((addr + 7) & 7) equals 7, so the ">=" could > be "==". >
I think it should be "==", the value will not "> 7"
> I think. The code looks a bit weird. A code comment would help. > > And how come memory_is_poisoned_16() does IS_ALIGNED(addr, 8)? Should > it be 16?
No, it is to determine whether the shadow span two bytes(8 bytes, not 16).
Thanks, Xishi Qiu
> > > . >
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