Patchwork [U-Boot,1/1] nios2 - adjust gbl data off to account for bd_info

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Submitter Alex Hornung
Date Feb. 20, 2012, 11:45 p.m.
Message ID <1329781545-18177-1-git-send-email-alex@alexhornung.com>
Download mbox | patch
Permalink /patch/142260/
State Accepted
Commit bb60db634c26d609b289e114f44cc2c94ee64c4f
Delegated to: Thomas Chou
Headers show

Comments

Alex Hornung - Feb. 20, 2012, 11:45 p.m.
* Adjust the GBL_DATA_OFFSET to account for the fact that we'll be
   using the space between that offset and the start of the malloc
   region to allocate both a gd structure and a board info structure.

 * This fixes a memory corruption bug due to overlap of the malloc
   region and the bd_info structure.

Signed-off-by: Alex Hornung <alex@alexhornung.com>
---
 include/configs/nios2-generic.h |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
Graeme Russ - Feb. 21, 2012, 10:33 a.m.
Hi Alex,

On 02/21/2012 10:45 AM, Alex Hornung wrote:
>  * Adjust the GBL_DATA_OFFSET to account for the fact that we'll be
>    using the space between that offset and the start of the malloc
>    region to allocate both a gd structure and a board info structure.
> 
>  * This fixes a memory corruption bug due to overlap of the malloc
>    region and the bd_info structure.
> 
> Signed-off-by: Alex Hornung <alex@alexhornung.com>
> ---
>  include/configs/nios2-generic.h |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/include/configs/nios2-generic.h b/include/configs/nios2-generic.h
> index 9ba35e8..17017a5 100644
> --- a/include/configs/nios2-generic.h
> +++ b/include/configs/nios2-generic.h
> @@ -131,7 +131,8 @@
>  #define CONFIG_SYS_MALLOC_BASE		(CONFIG_SYS_MONITOR_BASE - \
>  					 CONFIG_SYS_MALLOC_LEN)
>  #define CONFIG_SYS_GBL_DATA_OFFSET	(CONFIG_SYS_MALLOC_BASE - \
> -					 GENERATED_GBL_DATA_SIZE)
> +					 GENERATED_GBL_DATA_SIZE - \
> +					 GENERATED_BD_INFO_SIZE)
>  #define CONFIG_SYS_INIT_SP		CONFIG_SYS_GBL_DATA_OFFSET
>  
>  /*

Oh I really want to NAK this, but I think I might be out-voted

in arch/x86/lib/init_helpers.c I do:

bd_t bd_data;

int init_bd_struct_r(void)
{
	gd->bd = &bd_data;
	memset(gd->bd, 0, sizeof(bd_t));

	return 0;
}

So the bd struct is in bss

But everyone else (ARM, PPC) seems to do:

	addr_sp -= sizeof(bd_t);
	bd = (bd_t *) addr_sp;

Why?

Well I see that a lot of bd is setup while still running from flash, so bss
is not available. But is this really necessary?

And for the sake of one more copy and pointer adjustment, even gd could be
moved into bss which would save all the hackish calculations of sticking gd
and bd in a magic void below the stack

But maybe that's a battle for another day...

Oh, and Nios is particularly nasty - It has no init_r / init_f so there is
no support for relocation - Will there every be an intent to enable
relocation for Nios or is it pointless?

Regards,

Graeme
Alex Hornung - Feb. 23, 2012, 8:13 a.m.
Hi Graeme,

On 21/02/12 10:33, Graeme Russ wrote:
> Hi Alex,
> 
> On 02/21/2012 10:45 AM, Alex Hornung wrote:
>>  * Adjust the GBL_DATA_OFFSET to account for the fact that we'll be
>>    using the space between that offset and the start of the malloc
>>    region to allocate both a gd structure and a board info structure.
>>
>>  * This fixes a memory corruption bug due to overlap of the malloc
>>    region and the bd_info structure.
>>
>> Signed-off-by: Alex Hornung <alex@alexhornung.com>
>> ---
>>  include/configs/nios2-generic.h |    3 ++-
>>  1 files changed, 2 insertions(+), 1 deletions(-)
>>
>> diff --git a/include/configs/nios2-generic.h b/include/configs/nios2-generic.h
>> index 9ba35e8..17017a5 100644
>> --- a/include/configs/nios2-generic.h
>> +++ b/include/configs/nios2-generic.h
>> @@ -131,7 +131,8 @@
>>  #define CONFIG_SYS_MALLOC_BASE		(CONFIG_SYS_MONITOR_BASE - \
>>  					 CONFIG_SYS_MALLOC_LEN)
>>  #define CONFIG_SYS_GBL_DATA_OFFSET	(CONFIG_SYS_MALLOC_BASE - \
>> -					 GENERATED_GBL_DATA_SIZE)
>> +					 GENERATED_GBL_DATA_SIZE - \
>> +					 GENERATED_BD_INFO_SIZE)
>>  #define CONFIG_SYS_INIT_SP		CONFIG_SYS_GBL_DATA_OFFSET
>>  
>>  /*
> 
> Oh I really want to NAK this, but I think I might be out-voted
> 
> in arch/x86/lib/init_helpers.c I do:
> 
> bd_t bd_data;
> 
> int init_bd_struct_r(void)
> {
> 	gd->bd = &bd_data;
> 	memset(gd->bd, 0, sizeof(bd_t));
> 
> 	return 0;
> }
> 
> So the bd struct is in bss
> 
> But everyone else (ARM, PPC) seems to do:
> 
> 	addr_sp -= sizeof(bd_t);
> 	bd = (bd_t *) addr_sp;
> 
> Why?
> 
> Well I see that a lot of bd is setup while still running from flash, so bss
> is not available. But is this really necessary?
> 
> And for the sake of one more copy and pointer adjustment, even gd could be
> moved into bss which would save all the hackish calculations of sticking gd
> and bd in a magic void below the stack
> 
> But maybe that's a battle for another day...

To be honest I just started using u-boot, and for that matter, just
started using Nios2. I just ran across the issue and had to fix it to
get u-boot working on my system.

Nonetheless I'd generally agree that less hackery is a better idea, and
putting it in BSS is a good option - but reality is, as you point out,
that most other platforms don't do that, either. For now I think the
above patch should do.

> Oh, and Nios is particularly nasty - It has no init_r / init_f so there is
> no support for relocation - Will there every be an intent to enable
> relocation for Nios or is it pointless?

As I mentioned I'm not really involved with u-boot on Nios, so I can't
answer that question.


Cheers,
Alex
Graeme Russ - Feb. 23, 2012, 8:49 a.m.
Hi Alex,

On 02/23/2012 07:13 PM, Alex Hornung wrote:
> Hi Graeme,
> 
> On 21/02/12 10:33, Graeme Russ wrote:
>> Hi Alex,
>>
>> On 02/21/2012 10:45 AM, Alex Hornung wrote:
>>>  * Adjust the GBL_DATA_OFFSET to account for the fact that we'll be
>>>    using the space between that offset and the start of the malloc
>>>    region to allocate both a gd structure and a board info structure.
>>>
>>>  * This fixes a memory corruption bug due to overlap of the malloc
>>>    region and the bd_info structure.
>>>
>>> Signed-off-by: Alex Hornung <alex@alexhornung.com>
>>> ---
>>>  include/configs/nios2-generic.h |    3 ++-
>>>  1 files changed, 2 insertions(+), 1 deletions(-)
>>>

[snip]

>> And for the sake of one more copy and pointer adjustment, even gd could be
>> moved into bss which would save all the hackish calculations of sticking gd
>> and bd in a magic void below the stack
>>
>> But maybe that's a battle for another day...
> 
> To be honest I just started using u-boot, and for that matter, just
> started using Nios2. I just ran across the issue and had to fix it to
> get u-boot working on my system.
> 
> Nonetheless I'd generally agree that less hackery is a better idea, and
> putting it in BSS is a good option - but reality is, as you point out,
> that most other platforms don't do that, either. For now I think the
> above patch should do.

I agree - as I said, a battle for another day :)

Regards,

Graeme
Mike Frysinger - Feb. 23, 2012, 11:54 p.m.
On Monday 20 February 2012 18:45:45 Alex Hornung wrote:
>  * Adjust the GBL_DATA_OFFSET to account for the fact that we'll be
>    using the space between that offset and the start of the malloc
>    region to allocate both a gd structure and a board info structure.
> 
>  * This fixes a memory corruption bug due to overlap of the malloc
>    region and the bd_info structure.
> 
> Signed-off-by: Alex Hornung <alex@alexhornung.com>
> ---
>  include/configs/nios2-generic.h |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/include/configs/nios2-generic.h
> b/include/configs/nios2-generic.h index 9ba35e8..17017a5 100644
> --- a/include/configs/nios2-generic.h
> +++ b/include/configs/nios2-generic.h
> @@ -131,7 +131,8 @@
>  #define CONFIG_SYS_MALLOC_BASE		(CONFIG_SYS_MONITOR_BASE - \
>  					 CONFIG_SYS_MALLOC_LEN)
>  #define CONFIG_SYS_GBL_DATA_OFFSET	(CONFIG_SYS_MALLOC_BASE - \
> -					 GENERATED_GBL_DATA_SIZE)
> +					 GENERATED_GBL_DATA_SIZE - \
> +					 GENERATED_BD_INFO_SIZE)
>  #define CONFIG_SYS_INIT_SP		CONFIG_SYS_GBL_DATA_OFFSET
> 
>  /*

+cc the nios maintainers ...
-mike
Thomas Chou - Feb. 24, 2012, 3:03 a.m.
On 02/21/2012 07:45 AM, Alex Hornung wrote:
>   * Adjust the GBL_DATA_OFFSET to account for the fact that we'll be
>     using the space between that offset and the start of the malloc
>     region to allocate both a gd structure and a board info structure.
>
>   * This fixes a memory corruption bug due to overlap of the malloc
>     region and the bd_info structure.
>
> Signed-off-by: Alex Hornung<alex@alexhornung.com>
> ---
>   include/configs/nios2-generic.h |    3 ++-
>   1 files changed, 2 insertions(+), 1 deletions(-)
>

Dear Alex,

Applied. Thanks.

Best regards,
Thomas

Patch

diff --git a/include/configs/nios2-generic.h b/include/configs/nios2-generic.h
index 9ba35e8..17017a5 100644
--- a/include/configs/nios2-generic.h
+++ b/include/configs/nios2-generic.h
@@ -131,7 +131,8 @@ 
 #define CONFIG_SYS_MALLOC_BASE		(CONFIG_SYS_MONITOR_BASE - \
 					 CONFIG_SYS_MALLOC_LEN)
 #define CONFIG_SYS_GBL_DATA_OFFSET	(CONFIG_SYS_MALLOC_BASE - \
-					 GENERATED_GBL_DATA_SIZE)
+					 GENERATED_GBL_DATA_SIZE - \
+					 GENERATED_BD_INFO_SIZE)
 #define CONFIG_SYS_INIT_SP		CONFIG_SYS_GBL_DATA_OFFSET
 
 /*