On 31.05.23 14:38, Sascha Hauer wrote:
> On Wed, May 31, 2023 at 01:58:33PM +0200, Ahmad Fatoum wrote:
>>> From b6e5c92682467496bd9c57918996f1feffda2dd6 Mon Sep 17 00:00:00 2001
>>> From: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
>>> Date: Wed, 31 May 2023 11:58:51 +0200
>>> Subject: [PATCH] ARM: mmu_32: fix setting up zero page when it is in SDRAM
>>>
>>> We used to skip setting the zero page to faulting when SDRAM starts at
>>> 0x0. As bootm code now explicitly sets the zero page accessible before
>>> copying ATAGs there this should no longer be necessary, so
>>> unconditionally set the zero page to faulting during MMU startup. This
>>> also moves the zero page and vector table setup after the point the
>>> SDRAM has been mapped cachable, because otherwise the zero page and
>>> possibly the vector table mapping would be overwritten.
>>>
>>> Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
>>> ---
>>> arch/arm/cpu/mmu_32.c | 23 +++++++++--------------
>>> 1 file changed, 9 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/arch/arm/cpu/mmu_32.c b/arch/arm/cpu/mmu_32.c
>>> index c4e5a3bb0a..14775768a3 100644
>>> --- a/arch/arm/cpu/mmu_32.c
>>> +++ b/arch/arm/cpu/mmu_32.c
>>> @@ -461,19 +461,14 @@ static int set_vector_table(unsigned long adr)
>>>
>>> static void create_zero_page(void)
>>
>> Is this commit incomplete? Vectors should be set up unconditionally and
>> create_zero_page should be called after it.
>
> Vectors are set up unconditionally and create_zero_page() is called the
> same way as before.
So zero page is requested first and then on platforms with vector at
address 0 requesting fails and we are left without configured IVT?
>
> Sascha
>
>>
>>> {
>>> - struct resource *zero_sdram;
>>> + /*
>>> + * In case the zero page is in SDRAM request it to prevent others
>>> + * from using it
>>> + */
>>> + request_sdram_region("zero page", 0x0, PAGE_SIZE);
>>>
>>> - zero_sdram = request_sdram_region("zero page", 0x0, PAGE_SIZE);
>>> - if (zero_sdram) {
>>> - /*
>>> - * Here we would need to set the second level page table
>>> - * entry to faulting. This is not yet implemented.
>>> - */
>>> - pr_debug("zero page is in SDRAM area, currently not supported\n");
>>> - } else {
>>> - zero_page_faulting();
>>> - pr_debug("Created zero page\n");
>>> - }
>>> + zero_page_faulting();
>>> + pr_debug("Created zero page\n");
>>> }
>>>
>>> /*
>>> @@ -530,8 +525,6 @@ void __mmu_init(bool mmu_on)
>>>
>>> pr_debug("ttb: 0x%p\n", ttb);
>>>
>>> - vectors_init();
>>> -
>>> /*
>>> * Early mmu init will have mapped everything but the initial memory area
>>> * (excluding final OPTEE_SIZE bytes) uncached. We have now discovered
>>> @@ -552,6 +545,8 @@ void __mmu_init(bool mmu_on)
>>>
>>> remap_range((void *)pos, bank->start + bank->size - pos, MAP_CACHED);
>>> }
>>> +
>>> + vectors_init();
>>> }
>>>
>>> /*
>>
>> --
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>> Steuerwalder Str. 21 | http://www.pengutronix.de/ |
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>>
>>
>
--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
