From: amit.virdi@st•com (Amit Virdi)
To: linux-arm-kernel@lists•infradead.org
Subject: copy from user broken on no-MMU (Was: Need advice: unable to mount filesystem)
Date: Mon, 21 Oct 2013 16:59:54 +0530 [thread overview]
Message-ID: <52651032.3040505@st.com> (raw)
In-Reply-To: <20131016082019.GA10079@pengutronix.de>
Dear Uwe,
On 10/16/2013 1:50 PM, Uwe Kleine-K?nig wrote:
> Hello Amit,
>
> (fixed subject and added Nico to Cc:)
>
> On Wed, Oct 16, 2013 at 10:55:17AM +0530, Amit Virdi wrote:
>> I'm using cortex-R4 in my SoC. I figured earlier that the support
>> for MMU-less kernel was broken from Kernel v3.6 onwards. As a
>> result, I was facing problem in mounting the filesystem. Using git
>> bisect, I figured out that as a result of:
>>
>>> ARM: 7449/1: use generic strnlen_user and strncpy_from_user functions
>>
>> the file system was unable to mount on MMU-less kernel. Till date, I
>> have been using the following local fix [1]:
>>
>> ---
>> diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
>> index 479a635..e5d549f 100644
>> --- a/arch/arm/include/asm/uaccess.h
>> +++ b/arch/arm/include/asm/uaccess.h
>> @@ -190,7 +190,7 @@ static inline void set_fs(mm_segment_t fs)
>> #define access_ok(type,addr,size) (__range_ok(addr,size) == 0)
>>
>> #define user_addr_max() \
>> - (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
>> + (segment_eq(get_fs(), KERNEL_DL) ? ~0UL : TASK_SIZE)
>>
>> /*
>> * The "__xxx" versions of the user access functions do not verify the
> I did:
>
> http://git.pengutronix.de/?p=ukl/linux.git;a=commitdiff;h=089c629270ccd7499a083b530ec6aecc101d078b
>
> but I'm not sure either this is correct. I asked here on the list back
> then with the same patch as your's[1].
>
> [1] http://thread.gmane.org/gmane.linux.ports.arm.kernel/170980/focus=191855
Yes, I see. So what do you think is the best way to resolve this
problem? It is already lingering around for so long.
>> [2] The patch "ARM: move signal handlers into a vdso-like page"
>> introduced in v3.11-rc4 generates Prefetch abort while booting
>> kernel in MMU-less systems
> My M3 happily runs on v3.12-rc4.
>
I fixed a local problem and now I'm able to execute the Kernel on v3.12-rc5.
Regards
Amit Virdi
prev parent reply other threads:[~2013-10-21 11:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-13 12:29 Need advice: unable to mount filesystem Amit Virdi
2013-02-13 13:14 ` Linus Walleij
2013-02-14 2:57 ` Anil Kumar
2013-02-14 5:34 ` Amit Virdi
2013-02-14 5:24 ` Amit Virdi
2013-02-14 9:36 ` Linus Walleij
2013-02-15 11:55 ` Amit Virdi
2013-10-16 5:25 ` Amit Virdi
[not found] ` <20131016082019.GA10079@pengutronix.de>
2013-10-21 11:29 ` Amit Virdi [this message]
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