Patchwork [U-Boot] armv7: Fix infinite loop for the spl boot

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Submitter seedshope
Date July 6, 2012, 11:42 a.m.
Message ID <4FF6CF0A.7010300@gmail.com>
Download mbox | patch
Permalink /patch/169454/
State Superseded
Delegated to: Albert ARIBAUD
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seedshope - July 6, 2012, 11:42 a.m.
On 07/06/2012 01:35 AM, Albert ARIBAUD <albert.u.boot@aribaud.net> (by
way of Albert ARIBAUD wrote:
> Hi Zhong Hongbo,
> 
> On Thu, 05 Jul 2012 19:53:46 +0800, Zhong Hongbo <bocui107@gmail.com>
> wrote:
>> Hi Albert,
>>
>> Could you applied the patch to the arm tree?
>>
>> Thanks,
>> hongbo
>> On 07/03/2012 07:46 AM, Zhong Hongbo wrote:
>>> From: Zhong Hongbo <bocui107@gmail.com>
>>>
>>> In the spl booting step, When __bss_start is equal to __bss_end__,
>>> The loop will clear all the things in CPU space. If there are have
>>> the same address for this symbol, To skip the clear bss section.
>>>
>>> Signed-off-by: Hongbo Zhong <bocui107@gmail.com>
>>> ---
>>>  arch/arm/cpu/armv7/start.S |    3 +++
>>>  1 files changed, 3 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
>>> index 76ccef1..c72f337 100644
>>> --- a/arch/arm/cpu/armv7/start.S
>>> +++ b/arch/arm/cpu/armv7/start.S
>>> @@ -258,6 +258,8 @@ clear_bss:
>>>  	/* No relocation for SPL */
>>>  	ldr	r0, =__bss_start
>>>  	ldr	r1, =__bss_end__
>>> +	cmp	r0, r1
>>> +	beq	skip_clbss
>>>  #else
>>>  	ldr	r0, _bss_start_ofs
>>>  	ldr	r1, _bss_end_ofs
>>> @@ -271,6 +273,7 @@ clbss_l:str	r2, [r0]		/*
>>> clear loop...		    */ add	r0, r0, #4
>>>  	cmp	r0, r1
>>>  	bne	clbss_l
>>> +skip_clbss:
> 
> Clearly the loop was wrong in that it should implement a "for (r0 =
> start; r0 < end; r0++)" but actually implements a "for (r0 =
> start; r0 != end; r0++)".
> 

Yes， My new patch have do this.
> I'd rather the loop be fixed to match the intended implementation
> rather than worked around. Please rewrite your patch to turn:
> 

Ok, I just found the issue have found in other arm platfor 2011 yeas,
the detail information as following:

commit 8f1da53508c78789ebeea98a92a3f55c3f84dc5d
Author: Christian Riesch <christian.riesch@omicron.at>
Date:   Wed Nov 30 22:27:37 2011 +0000

    arm, arm926ejs: Fix clear bss loop for zero length bss

    This patch fixes the clear bss loop for bss sections that have
    zero length, i.e., where __bss_start == __bss_end__.

    Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
    Cc: Albert Aribaud <albert.u.boot@aribaud.net>

>>         add     r0, r0, #4
>>         cmp     r0, r1
>>         bne     clbss_l
> 
> Into something like
> 
>> clbss_l:cmp     r0, r1
>>         blo     clbss_d
>>         str     r2, [r0]  /* clear loop...*/
>>         add     r0, r0, #4
>>         b       clbss_l
>> clbss_d:
> 
> Also, as Andreas points out, make sure the same fix is applied to all ARM start.S files which need it.

Ok，

Thanks,
hongbo
> 
> Thanks in advance.
> 
> Amicalement,
>
Andreas Bießmann - July 6, 2012, 11:49 a.m.
Dear Zhong Hongbo,

On 06.07.2012 13:42, Zhong Hongbo wrote:
> On 07/06/2012 01:35 AM, Albert ARIBAUD <albert.u.boot@aribaud.net> (by
> way of Albert ARIBAUD wrote:
>> Hi Zhong Hongbo,
>>
>> On Thu, 05 Jul 2012 19:53:46 +0800, Zhong Hongbo <bocui107@gmail.com>
>> wrote:

<snip>

> 
> Ok, I just found the issue have found in other arm platfor 2011 yeas,
> the detail information as following:
> 
> commit 8f1da53508c78789ebeea98a92a3f55c3f84dc5d
> Author: Christian Riesch <christian.riesch@omicron.at>
> Date:   Wed Nov 30 22:27:37 2011 +0000
> 
>     arm, arm926ejs: Fix clear bss loop for zero length bss
> 
>     This patch fixes the clear bss loop for bss sections that have
>     zero length, i.e., where __bss_start == __bss_end__.
> 
>     Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
>     Cc: Albert Aribaud <albert.u.boot@aribaud.net>
> 
> diff --git a/arch/arm/cpu/arm926ejs/start.S b/arch/arm/cpu/arm926ejs/start.S
> index 339c5ed..bb4d00b 100644
> --- a/arch/arm/cpu/arm926ejs/start.S
> +++ b/arch/arm/cpu/arm926ejs/start.S
> @@ -301,10 +301,12 @@ clear_bss:
>  #endif
>         mov     r2, #0x00000000         /* clear
>     */
> 
> -clbss_l:str    r2, [r0]                /* clear loop...
>     */
> +clbss_l:cmp    r0, r1                  /* clear loop... */
> +       bhs     clbss_e                 /* if reached end of bss, exit */
> +       str     r2, [r0]
>         add     r0, r0, #4
> -       cmp     r0, r1
> -       bne     clbss_l
> +       b       clbss_l
> +clbss_e:
>>> clbss_l:str     r2, [r0]  /* clear loop...*/
>>>         add     r0, r0, #4
>>>         cmp     r0, r1
>>>         bne     clbss_l
>>
>> Into something like
>>
>>> clbss_l:cmp     r0, r1
>>>         blo     clbss_d
>>>         str     r2, [r0]  /* clear loop...*/
>>>         add     r0, r0, #4
>>>         b       clbss_l
>>> clbss_d:
>>
>> Also, as Andreas points out, make sure the same fix is applied to all ARM start.S files which need it.
> 
> Ok，

I think this is the thread we will proceed.
So as I understand we had missed in 2011 to update the other start.S
with a fix found by Christian Riesch for arm926ejs. So please do update
_all_ start.S (of arm;) now. I think they do have all the same error
cause we copied it over from one to the other when implementing the 'new
relocation' stuff.

Best regards

Andreas Bießmann
seedshope - July 6, 2012, 11:53 a.m.
On 07/06/2012 07:49 PM, Andreas Bießmann wrote:
> Dear Zhong Hongbo,
> 
> On 06.07.2012 13:42, Zhong Hongbo wrote:
>> On 07/06/2012 01:35 AM, Albert ARIBAUD <albert.u.boot@aribaud.net> (by
>> way of Albert ARIBAUD wrote:
>>> Hi Zhong Hongbo,
>>>
>>> On Thu, 05 Jul 2012 19:53:46 +0800, Zhong Hongbo <bocui107@gmail.com>
>>> wrote:
> 
> <snip>
> 
>>
>> Ok, I just found the issue have found in other arm platfor 2011 yeas,
>> the detail information as following:
>>
>> commit 8f1da53508c78789ebeea98a92a3f55c3f84dc5d
>> Author: Christian Riesch <christian.riesch@omicron.at>
>> Date:   Wed Nov 30 22:27:37 2011 +0000
>>
>>     arm, arm926ejs: Fix clear bss loop for zero length bss
>>
>>     This patch fixes the clear bss loop for bss sections that have
>>     zero length, i.e., where __bss_start == __bss_end__.
>>
>>     Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
>>     Cc: Albert Aribaud <albert.u.boot@aribaud.net>
>>
>> diff --git a/arch/arm/cpu/arm926ejs/start.S b/arch/arm/cpu/arm926ejs/start.S
>> index 339c5ed..bb4d00b 100644
>> --- a/arch/arm/cpu/arm926ejs/start.S
>> +++ b/arch/arm/cpu/arm926ejs/start.S
>> @@ -301,10 +301,12 @@ clear_bss:
>>  #endif
>>         mov     r2, #0x00000000         /* clear
>>     */
>>
>> -clbss_l:str    r2, [r0]                /* clear loop...
>>     */
>> +clbss_l:cmp    r0, r1                  /* clear loop... */
>> +       bhs     clbss_e                 /* if reached end of bss, exit */
>> +       str     r2, [r0]
>>         add     r0, r0, #4
>> -       cmp     r0, r1
>> -       bne     clbss_l
>> +       b       clbss_l
>> +clbss_e:
>>>> clbss_l:str     r2, [r0]  /* clear loop...*/
>>>>         add     r0, r0, #4
>>>>         cmp     r0, r1
>>>>         bne     clbss_l
>>>
>>> Into something like
>>>
>>>> clbss_l:cmp     r0, r1
>>>>         blo     clbss_d
>>>>         str     r2, [r0]  /* clear loop...*/
>>>>         add     r0, r0, #4
>>>>         b       clbss_l
>>>> clbss_d:
>>>
>>> Also, as Andreas points out, make sure the same fix is applied to all ARM start.S files which need it.
>>
>> Ok，
> 
> I think this is the thread we will proceed.
> So as I understand we had missed in 2011 to update the other start.S
> with a fix found by Christian Riesch for arm926ejs. So please do update
> _all_ start.S (of arm;) now. I think they do have all the same error
> cause we copied it over from one to the other when implementing the 'new
> relocation' stuff.
Agree, I will do it now.

Thanks,
hongbo
> 
> Best regards
> 
> Andreas Bießmann
> 
>

Patch

diff --git a/arch/arm/cpu/arm926ejs/start.S b/arch/arm/cpu/arm926ejs/start.S
index 339c5ed..bb4d00b 100644
--- a/arch/arm/cpu/arm926ejs/start.S
+++ b/arch/arm/cpu/arm926ejs/start.S
@@ -301,10 +301,12 @@  clear_bss:
 #endif
        mov     r2, #0x00000000         /* clear
    */

-clbss_l:str    r2, [r0]                /* clear loop...
    */
+clbss_l:cmp    r0, r1                  /* clear loop... */
+       bhs     clbss_e                 /* if reached end of bss, exit */
+       str     r2, [r0]
        add     r0, r0, #4
-       cmp     r0, r1
-       bne     clbss_l
+       b       clbss_l
+clbss_e:
>> clbss_l:str     r2, [r0]  /* clear loop...*/