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

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Submitter seedshope
Date July 2, 2012, 11:46 p.m.
Message ID <1341272798-3460-1-git-send-email-bocui107@gmail.com>
Download mbox | patch
Permalink /patch/168659/
State Superseded
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Comments

seedshope - July 2, 2012, 11:46 p.m.
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(-)
seedshope - July 5, 2012, 11:53 a.m.
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:
>  
>  /*
>   * We are done. Do not return, instead branch to second part of board
>
Albert ARIBAUD - July 5, 2012, 12:19 p.m.
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++)".

I'd rather the loop be fixed to match the intended implementation
rather than worked around. Please rewrite your patch to turn:

> 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:

Thanks in advance.

Amicalement,
seedshope - July 5, 2012, 12:34 p.m.
Hi Albert,
On 07/05/2012 08:19 PM, 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++)".
Ok, Good to known, I will send V2
> 
> I'd rather the loop be fixed to match the intended implementation
> rather than worked around. Please rewrite your patch to turn:
Ok,

Thanks,
hongbo
> 
>> 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:
> 
> Thanks in advance.
> 
> Amicalement,
>
Albert ARIBAUD - July 5, 2012, 5:35 p.m.
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++)".

I'd rather the loop be fixed to match the intended implementation
rather than worked around. Please rewrite your patch to turn:

> 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.

Thanks in advance.

Amicalement,

Patch

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:
 
 /*
  * We are done. Do not return, instead branch to second part of board