[U-Boot] [PATCH V2] spl: Weed out CONFIG_SYS_TEXT_BASE usage

[Marek Vasut]

On 08/14/2018 08:25 PM, Simon Goldschmidt wrote:
> On Tue, Aug 14, 2018 at 8:17 PM Marek Vasut <marex at denx.de> wrote:
>>
>> On 08/14/2018 02:56 PM, Simon Goldschmidt wrote:
>>> On Tue, Aug 14, 2018 at 2:05 PM Marek Vasut <marex at denx.de> wrote:
>>>>
>>>> On 08/14/2018 12:22 PM, Simon Goldschmidt wrote:
>>>>> On Tue, Aug 14, 2018 at 12:10 PM Marek Vasut <marex at denx.de> wrote:
>>>>>>
>>>>>> On 08/14/2018 11:51 AM, Simon Goldschmidt wrote:
>>>>>>> On Tue, Aug 14, 2018 at 11:27 AM Marek Vasut <marex at denx.de> wrote:
>>>>>>>>
>>>>>>>> The SPL loaders assume that the CONFIG_SYS_TEXT_BASE memory location
>>>>>>>> is available and can be corrupted by loading ie. uImage or fitImage
>>>>>>>> headers there. Sometimes it could be beneficial to load the headers
>>>>>>>> elsewhere, ie. if CONFIG_SYS_TEXT_BASE is not yet writable while we
>>>>>>>> still want to parse the image headers in some local onchip memory to
>>>>>>>> ie. extract firmware from that image.
>>>>>>>>
>>>>>>>> Add the possibility to override the location where the headers get
>>>>>>>> loaded by introducing new function, spl_get_load_buffer() which takes
>>>>>>>> two arguments -- offset from the CONFIG_SYS_TEXT_BASE and size of the
>>>>>>>> data that are to be loaded there -- and returns a valid buffer address
>>>>>>>> or hangs the system. The default behavior is the same as before, add
>>>>>>>> the offset to CONFIG_SYS_TEXT_BASE and return that address. User can
>>>>>>>> override the weak spl_get_load_buffer() function though.
>>>>>>>>
>>>>>>>> Signed-off-by: Marek Vasut <marex at denx.de>
>>>>>>>> Cc: Tom Rini <trini at konsulko.com>
>>>>>>>> ---
>>>>>>>> V2: Fix build issues on multiple boards due to incorrect pointer casting
>>>>>>
>>>>>> [...]
>>>>>>
>>>>>>>> diff --git a/common/spl/spl_ram.c b/common/spl/spl_ram.c
>>>>>>>> index e594beaeaa..619b39a537 100644
>>>>>>>> --- a/common/spl/spl_ram.c
>>>>>>>> +++ b/common/spl/spl_ram.c
>>>>>>>> @@ -63,8 +63,9 @@ static int spl_ram_load_image(struct spl_image_info *spl_image,
>>>>>>>>                          * No binman support or no information. For now, fix it
>>>>>>>>                          * to the address pointed to by U-Boot.
>>>>>>>>                          */
>>>>>>>> -                       u_boot_pos = CONFIG_SYS_TEXT_BASE -
>>>>>>>> -                                       sizeof(struct image_header);
>>>>>>>> +                       header = spl_get_load_buffer(-sizeof(*header),
>>>>>>>> +                                                    sizeof(*header));
>>>>>>>> +
>>>>>>>
>>>>>>> Using "spl_get_load_buffer()" here seems to be a bit misleading, as
>>>>>>> the address is used for "execute-in-place", not for loading.
>>>>>>
>>>>>> Do you have a better solution ? Instead of hard-coding the load buffer
>>>>>> address with some macro, this uses function which could be overridden.
>>>>>> Whether it's XIP or not has nothing to do with it.
>>>>>
>>>>> I meant the name is a bit misleading as it implies loading. But since
>>>>> the preferred way to do this is using binman, it's probably not worth
>>>>> adding yet another weak function for RAM boot?
>>>>
>>>> Do you have a better name that fits all the other usecases ? This
>>>> function just gets you buffer into which you can load the image.
>>>
>>> Not really. I just wonder if you have to override the location for
>>> some board, RAM booting might not work any more as it relies on a
>>> fixed address, not some generic buffer.
>>
>> I do, yeah, the board is not upstream completely yet though, so I am
>> just sending this as a cleanup.
>>
>>> Maybe we could add the boot device to your new weak function? If we
>>> add some comment to the new weak function, that would have made it
>>> much more clear for me how to boot U-Boot from FPGA OnChip RAM when I
>>> tried some months ago :-)
>>
>> This really just gives you a buffer. I don't need to know which boot
>> media is used. If there is a usecase, sure, it can be added later.
> 
> I may have a use case for one of our custom boards, but it's probably
> not worth doing that now.

Subsequent patch then ?

>>>>>>>>                 }
>>>>>>>>                 header = (struct image_header *)map_sysmem(u_boot_pos, 0);
>>>>>>>>
>>>>>>>> diff --git a/common/spl/spl_spi.c b/common/spl/spl_spi.c
>>>>>>>> index ba60a3a3c5..e10cf0124f 100644
>>>>>>>> --- a/common/spl/spl_spi.c
>>>>>>>> +++ b/common/spl/spl_spi.c
>>>>>>>> @@ -88,8 +88,7 @@ static int spl_spi_load_image(struct spl_image_info *spl_image,
>>>>>>>>                 return -ENODEV;
>>>>>>>>         }
>>>>>>>>
>>>>>>>> -       /* use CONFIG_SYS_TEXT_BASE as temporary storage area */
>>>>>>>> -       header = (struct image_header *)(CONFIG_SYS_TEXT_BASE);
>>>>>>>> +       header = spl_get_load_buffer(-sizeof(*header), 0x40);
>>>>>>>
>>>>>>> Shouldn't the first argument be 0 here instead of -sizeof(*header)?
>>>>>>
>>>>>> No, because then the payload doesn't end up at CONFIG_SYS_TEXT_BASE .
>>>>>
>>>>> Sorry, I haven't studied the code around the patch, only the patch.
>>>>> And I still think "header" has changed from "CONFIG_SYS_TEXT_BASE" to
>>>>> "CONFIG_SYS_TEXT_BASE - sizeof(*header)" with your patch. That might
>>>>> be a change required to get it work, I don't know that. But as this
>>>>> isn' mentioned in the commit message, to me it seemed like a copy and
>>>>> paste error or something.
>>>>
>>>> I suspect it's the SPI that's weird. Look at the surrounding code, IMO
>>>> this is how it should be.
>>>
>>> Reading the code, I guess the exact location of 'header' is not
>>> important. So the code should still work after applying your patch,
>>> even if it changes the location of 'header'.
>>
>> The thing is, the payload (ie. uboot) is linked against the TEXT_BASE,
>> so putting it at TEXT_BASE + offset can cause trouble.
> 
> Right. All I wanted to say is I saw something that changed but from
> the commit message, it didn't seem like it was intended.
> The rest seems fine to me right now, so if it's of any use:
> 
> Reviewed-by: Simon Goldschmidt <simon.k.r.goldschmidt at gmail.com>
> 


-- 
Best regards,
Marek Vasut