Subject: [PATCH v2 1/1] ARM: LPAE: Fix mapping in alloc_init_pte for unaligned addresses.

From: [email-masked] (Sricharan R)
Date: Fri, 15 Mar 2013 12:28:51 +0530

Hi,
On Friday 15 March 2013 01:49 AM, Laura Abbott wrote:
> On 3/13/2013 10:14 PM, Catalin Marinas wrote:
>> (sorry for if you got this message twice, gmail's new reply method
>> decided to send html)
>>
>> On 18 September 2012 12:52, R, Sricharan <[email-masked]> wrote:
>>> Hi,
>>> On Fri, Aug 17, 2012 at 4:32 PM, R, Sricharan <[email-masked]> wrote:
>>>> Hi,
>>>>
>>>>> With LPAE, When either the start address or end address
>>>>> or physical address to be mapped is unaligned,
>>>>> alloc_init_section creates page granularity mappings.
>>>>> alloc_init_section calls alloc_init_pte which populates
>>>>> one pmd entry and sets up the ptes. But if the size is
>>>>> greater than what can be mapped by one pmd entry,
>>>>> then the rest remains unmapped.
>>>>>
>>>>> The issue becomes visible when LPAE is enabled, where we have
>>>>> the 3 levels with seperate pgd and pmd's.
>>>>> When a static mapping for 3MB is requested, only 2MB is mapped
>>>>> and the remaining 1MB is unmapped. Fixing this here, by looping
>>>>> in to map the entire unaligned address range.
>>>>>
>>>>> Boot tested on OMAP5 evm with both LPAE enabled/disabled
>>>>> and verified that static mappings with unaligned addresses
>>>>> are properly mapped.
>>>>>
>>>>> Signed-off-by: R Sricharan <[email-masked]>
>>>>> Reviewed-by: Santosh Shilimkar <[email-masked]>
>>>>> Cc: Catalin Marinas <[email-masked]>
>>>>> ---
>>>>> [V2] Moved the loop to alloc_init_pte as per Russell's
>>>>>       feedback and changed the subject accordingly.
>>>>>       Using PMD_XXX instead of SECTION_XXX to avoid
>>>>>       different loop increments with/without LPAE.
>>>>>
>>>>>   arch/arm/mm/mmu.c |   22 ++++++++++++++++++----
>>>>>   1 file changed, 18 insertions(+), 4 deletions(-)
>>>>>
>>>>> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
>>>>> index cf4528d..0ed8808 100644
>>>>> --- a/arch/arm/mm/mmu.c
>>>>> +++ b/arch/arm/mm/mmu.c
>>>>> @@ -585,11 +585,25 @@ static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr,
>>>>>                                    unsigned long end, unsigned long pfn,
>>>>>                                    const struct mem_type *type)
>>>>>   {
>>>>> -       pte_t *pte = early_pte_alloc(pmd, addr, type->prot_l1);
>>>>> +       unsigned long next;
>>>>> +       pte_t *pte;
>>>>> +       phys_addr_t phys;
>>>>> +
>>>>>          do {
>>>>> -               set_pte_ext(pte, pfn_pte(pfn, __pgprot(type->prot_pte)), 0);
>>>>> -               pfn++;
>>>>> -       } while (pte++, addr += PAGE_SIZE, addr != end);
>>>>> +               if ((end-addr) & PMD_MASK)
>>>>> +                       next = (addr + PMD_SIZE) & PMD_MASK;
>>>>> +               else
>>>>> +                       next = end;
>>>>> +
>>>>> +               pte = early_pte_alloc(pmd, addr, type->prot_l1);
>>>>> +               do {
>>>>> +                       set_pte_ext(pte, pfn_pte(pfn,
>>>>> +                                       __pgprot(type->prot_pte)), 0);
>>>>> +                       pfn++;
>>>>> +               } while (pte++, addr += PAGE_SIZE, addr != next);
>>>>> +
>>>>> +               phys += next - addr;
>>>>> +       } while (pmd++, addr = next, addr != end);
>>>>>   }
>>>>>
>>>>    ping..
>>>
>>>    Ping again.
>>>    The issue is reproducible in mainline with CMA + LPAE enabled.
>>>    CMA tries to reserve/map 16 MB with 2 level table entries and
>>>     crashes in alloc_init_pte.
>>>
>>>    This patch fixes that. Just posted a V3 of the same patch.
>>>
>>>           https://patchwork.kernel.org/patch/1472031/
>>
>> I thought there was another patch where the looping was in an
>> alloc_init_pmd() function, or there are just two different threads. I
>> acked the other but not this one as I don't think looping over pmd
>> inside the alloc_init_pte() function is the right thing.
>>
> 
> I submitted a patch last week for what I think is the same issue ("arm: mm: Populate initial page tables across sections") but I don't think I ever saw any feedback on the patch. Do we have three patches floating around fixing the same issue?
> 
> Laura
> 
 your patch is looking like the intial version that i posted. So after some reviews,
 finally ended up with the below patch [1]. Can you please check if your issue gets
 fixed with this.

 [1] http://permalink.gmane.org/gmane.linux.ports.arm.kernel/216880

Regards,
 Sricharan