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

[Zhong Hongbo]

On 07/06/2012 01:35 AM, Albert ARIBAUD <albert.u.boot at aribaud.net> (by
way of Albert ARIBAUD wrote:
> Hi Zhong Hongbo,
> 
> On Thu, 05 Jul 2012 19:53:46 +0800, Zhong Hongbo <bocui107 at 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 at 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 at 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 at 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 at omicron.at>
    Cc: Albert Aribaud <albert.u.boot at 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，

Thanks,
hongbo
> 
> Thanks in advance.
> 
> Amicalement,
>