From: gangchen@rdamicro•com (陈刚(Gangchen))
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 1/1] ARM : missing corrupted reg in __do_div_asm
Date: Tue, 29 Mar 2016 10:58:20 +0000 [thread overview]
Message-ID: <56FA5FCB.2050609@rdamicro.com> (raw)
In-Reply-To: <20160329103418.GX19428@n2100.arm.linux.org.uk>
On 03/29/2016 06:34 PM, Russell King - ARM Linux wrote:
> On Tue, Mar 29, 2016 at 11:26:05AM +0100, Dave Martin wrote:
>> On Tue, Mar 29, 2016 at 12:19:49PM +0200, Arnd Bergmann wrote:
>>> On Monday 28 March 2016 12:19:03 Chen Gang wrote:
>>>> __xl(R0 in little endian system, or R1 in big endian system) is corrupted
>>>> after calling __do_div64 and compiler is not informed about this in
>>>> macro __do_div_asm. If n is used again afterwards, __xl won't be
>>>> reloaded and n will contain incorrect value.
>>>>
>>>> Signed-off-by: Chen Gang <gangchen@rdamicro•com>
>>>> Signed-off-by: Chen Gang <chengang.beijing@gmail•com>
>>>> ---
>>> How did you find this? Did you run into this problem on a live system
>>> or see it through inspection?
>>>
We (in RDAMicro) found the problem when we added TLC nand support in
MTD driver.
I submit this patch several time last year.
And this patch also fix one problems of XFS:
http://permalink.gmane.org/gmane.comp.file-systems.xfs.general/69224
>>>> arch/arm/include/asm/div64.h | 6 ++++--
>>>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/arm/include/asm/div64.h b/arch/arm/include/asm/div64.h
>>>> index e1f0776..1a6e91a 100644
>>>> --- a/arch/arm/include/asm/div64.h
>>>> +++ b/arch/arm/include/asm/div64.h
>>>> @@ -35,12 +35,14 @@ static inline uint32_t __div64_32(uint64_t *n, uint32_t base)
>>>> register unsigned long long __n asm("r0") = *n;
>>>> register unsigned long long __res asm("r2");
>>>> register unsigned int __rem asm(__xh);
>>>> + register unsigned int __clobber asm(__xl);
>>>> asm( __asmeq("%0", __xh)
>>>> __asmeq("%1", "r2")
>>>> + __asmeq("%3", "r0")
>>>> + __asmeq("%4", "r4")
>>>> __asmeq("%2", "r0")
>>>> - __asmeq("%3", "r4")
>>>> "bl __do_div64"
>>>> - : "=r" (__rem), "=r" (__res)
>>>> + : "=r" (__rem), "=r" (__res), "=r" (__clobber)
>>>> : "r" (__n), "r" (__base)
>>>> : "ip", "lr", "cc");
>>>> *n = __res;
>>> Doesn't the clobber normally go in the third line along with
>>> "ip" and "lr"?
>> Since __xl is not used for any real argument to the asm, I think
>> we can just add __xl to the clobber list directly, without needing
>> to introduce an extra register variable ... no?
> No, you can't. The clobber list is not allowed to specify registers
> that may be used for input or output operands, and since __xl may be
> r0, and __n _is_ r0, you can't specify r0 in the clobber list.
>
next prev parent reply other threads:[~2016-03-29 10:58 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-28 4:19 [PATCH 1/1] ARM : missing corrupted reg in __do_div_asm Chen Gang
2016-03-29 10:19 ` Arnd Bergmann
2016-03-29 10:26 ` Dave Martin
2016-03-29 10:34 ` Russell King - ARM Linux
2016-03-29 10:56 ` Dave Martin
2016-03-30 3:27 ` 陈刚(Gangchen)
2016-03-30 14:07 ` Dave Martin
2016-03-31 7:56 ` 陈刚(Gangchen)
2016-03-31 10:30 ` Dave Martin
2016-03-31 11:20 ` 陈刚(Gangchen)
2016-03-31 11:41 ` Dave Martin
2016-04-01 4:22 ` [PATCH V3 1/1] ARM : missing corrupted reg in __div64_32 chengang
2016-04-01 8:56 ` Dave Martin
2016-04-01 10:28 ` [PATCH V4 " chengang
2016-04-01 11:03 ` Dave Martin
2016-04-01 11:25 ` [PATCH V5 " chengang
2016-04-01 11:34 ` Dave P Martin
2016-04-01 11:35 ` [PATCH V4 " 陈刚(Gangchen)
2016-03-31 11:41 ` [PATCH v2 " Chen Gang
2016-03-29 10:58 ` 陈刚(Gangchen) [this message]
[not found] </home/gachen/Re: [PATCH 1_1] ARM:r0 is also corrupted after calling __do_div64..eml>
2015-06-02 6:13 ` [PATCH 1/1] ARM : missing corrupted reg in __do_div_asm Chen Gang
2015-06-08 5:30 ` Chen Gang
2015-06-09 13:09 ` Russell King - ARM Linux
2015-06-28 11:29 ` Chen Gang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=56FA5FCB.2050609@rdamicro.com \
--to=gangchen@rdamicro$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox