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

[Catalin Marinas]

(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 <r.sricharan at ti.com> wrote:
> Hi,
> On Fri, Aug 17, 2012 at 4:32 PM, R, Sricharan <r.sricharan at ti.com> 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 <r.sricharan at ti.com>
>>> Reviewed-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
>>> Cc: Catalin Marinas <catalin.marinas at arm.com>
>>> ---
>>> [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.

-- 
Catalin