From: David Laight <David.Laight@ACULAB.COM>
To: 'Guohua Zhong' <zhongguohua1@huawei.com>,
"paubert@iram.es" <paubert@iram.es>
Cc: "wangle6@huawei.com" <wangle6@huawei.com>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"paulus@samba.org" <paulus@samba.org>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
"nixiaoming@huawei.com" <nixiaoming@huawei.com>
Subject: RE: Re：Re: [PATCH] powerpc: Fix a bug in __div64_32 if divisor is zero
Date: Mon, 24 Aug 2020 15:05:13 +0000 [thread overview]
Message-ID: <c200b38836674bbbb928bf76cbb978f1@AcuMS.aculab.com> (raw)
In-Reply-To: <20200824132539.35972-1-zhongguohua1@huawei.com>
From: Guohua Zhong
> Sent: 24 August 2020 14:26
>
> >> >In generic version in lib/math/div64.c, there is no checking of 'base'
> >> >either.
> >> >Do we really want to add this check in the powerpc version only ?
> >>
> >> >The only user of __div64_32() is do_div() in
> >> >include/asm-generic/div64.h. Wouldn't it be better to do the check there ?
> >>
> >> >Christophe
> >>
> >> Yet, I have noticed that there is no checking of 'base' in these functions.
> >> But I am not sure how to check is better.As we know that the result is
> >> undefined when divisor is zero. It maybe good to print error and dump stack.
I thought that the onus was put on the caller to avoid divide by zero.
On x86 divide by zero causes an exception which (I'm pretty sure)
leads to a oops/panic.
David
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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-08-24 15:16 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-20 13:10 [PATCH] powerpc: Fix a bug in __div64_32 if divisor is zero Guohua Zhong
2020-08-20 17:02 ` Christophe Leroy
2020-08-22 16:29 ` Guohua Zhong
2020-08-20 18:23 ` Christophe Leroy
2020-08-22 16:54 ` Re：Re: " Guohua Zhong
2020-08-22 17:25 ` Gabriel Paubert
2020-08-24 13:25 ` Guohua Zhong
2020-08-24 15:05 ` David Laight [this message]
2020-08-23 0:11 ` Segher Boessenkool
2020-08-24 11:54 ` Guohua Zhong
2020-08-24 18:17 ` Segher Boessenkool
2020-08-22 16:06 ` Guohua Zhong
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