Subject: [PATCH V6] ARM: LPAE: Fix mapping in alloc_init_section for unaligned addresses

From: [email-masked] (Sricharan R)
Date: Mon, 18 Mar 2013 16:24:16 +0530

Hi Russell,

On Monday 18 March 2013 04:15 PM, Russell King - ARM Linux wrote:
> On Mon, Mar 18, 2013 at 11:20:47AM +0530, Sricharan R wrote:
>> Hi Russell,
>>
>> On Monday 18 March 2013 01:22 AM, Christoffer Dall wrote:
>>> On Sat, Mar 16, 2013 at 10:05 PM, Sricharan R <[email-masked]> wrote:
>>>> From: R Sricharan <[email-masked]>
>>>>
>>>> With LPAE enabled, alloc_init_section() does not map the entire
>>>> address space for unaligned addresses.
>>>>
>>>> The issue also reproduced with CMA + LPAE. CMA tries to map 16MB
>>>> with page granularity mappings during boot. alloc_init_pte()
>>>> is called and out of 16MB, only 2MB gets mapped and rest remains
>>>> unaccessible.
>>>>
>>>> Because of this OMAP5 boot is broken with CMA + LPAE enabled.
>>>> Fix the issue by ensuring that the entire addresses are
>>>> mapped.
>>>>
>>>> Signed-off-by: R Sricharan <[email-masked]>
>>>> Cc: Catalin Marinas <[email-masked]>
>>>> Cc: Christoffer Dall <[email-masked]>
>>>> Cc: Russell King <[email-masked]>
>>>> Cc: Santosh Shilimkar <[email-masked]>
>>>> Tested-by: Laura Abbott <[email-masked]>
>>>> Acked-by: 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.
>>>>
>>>>  [v3] Removed the dummy variable phys and updated
>>>>       the commit log for CMA case.
>>>>
>>>>  [v4] Resending with updated change log and
>>>>       updating the tags.
>>>>
>>>>  [v5] Renamed alloc_init_section to alloc_init_pmd
>>>>       and moved the loop back there. Also introduced
>>>>       map_init_section as per Catalin's comments.
>>>>
>>>>  [v6] Corrected tags and updated the comments for code.
>>>>
>>>>  arch/arm/mm/mmu.c |   73 ++++++++++++++++++++++++++++++++++-------------------
>>>>  1 file changed, 47 insertions(+), 26 deletions(-)
>>>>
>>>> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
>>>> index e95a996..7897894 100644
>>>> --- a/arch/arm/mm/mmu.c
>>>> +++ b/arch/arm/mm/mmu.c
>>>> @@ -598,39 +598,60 @@ static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr,
>>>>         } while (pte++, addr += PAGE_SIZE, addr != end);
>>>>  }
>>>>
>>>> -static void __init alloc_init_section(pud_t *pud, unsigned long addr,
>>>> -                                     unsigned long end, phys_addr_t phys,
>>>> -                                     const struct mem_type *type)
>>>> +static void __init map_init_section(pmd_t *pmd, unsigned long addr,
>>>> +                       unsigned long end, phys_addr_t phys,
>>>> +                       const struct mem_type *type)
>>>>  {
>>>> -       pmd_t *pmd = pmd_offset(pud, addr);
>>>> -
>>>> +#ifndef CONFIG_ARM_LPAE
>>>>         /*
>>>> -        * Try a section mapping - end, addr and phys must all be aligned
>>>> -        * to a section boundary.  Note that PMDs refer to the individual
>>>> -        * L1 entries, whereas PGDs refer to a group of L1 entries making
>>>> -        * up one logical pointer to an L2 table.
>>>> +        * In classic MMU format, puds and pmds are folded in to
>>>> +        * the pgds. pmd_offset gives the PGD entry. PGDs refer to a
>>>> +        * group of L1 entries making up one logical pointer to
>>>> +        * an L2 table (2MB), where as PMDs refer to the individual
>>>> +        * L1 entries (1MB). Hence increment to get the correct
>>>> +        * offset for odd 1MB sections.
>>>> +        * (See arch/arm/include/asm/pgtable-2level.h)
>>>>          */
>>>> -       if (type->prot_sect && ((addr | end | phys) & ~SECTION_MASK) == 0) {
>>>> -               pmd_t *p = pmd;
>>>> -
>>>> -#ifndef CONFIG_ARM_LPAE
>>>> -               if (addr & SECTION_SIZE)
>>>> -                       pmd++;
>>>> +       if (addr & SECTION_SIZE)
>>>> +               pmd++;
>>>>  #endif
>>>> +       do {
>>>> +               *pmd = __pmd(phys | type->prot_sect);
>>>> +               phys += SECTION_SIZE;
>>>> +       } while (pmd++, addr += SECTION_SIZE, addr != end);
>>>>
>>>> -               do {
>>>> -                       *pmd = __pmd(phys | type->prot_sect);
>>>> -                       phys += SECTION_SIZE;
>>>> -               } while (pmd++, addr += SECTION_SIZE, addr != end);
>>>> +       flush_pmd_entry(pmd);
>>>> +}
>>>>
>>>> -               flush_pmd_entry(p);
>>>> -       } else {
>>>> +static void __init alloc_init_pmd(pud_t *pud, unsigned long addr,
>>>> +                                     unsigned long end, phys_addr_t phys,
>>>> +                                     const struct mem_type *type)
>>>> +{
>>>> +       pmd_t *pmd = pmd_offset(pud, addr);
>>>> +       unsigned long next;
>>>> +
>>>> +       do {
>>>>                 /*
>>>> -                * No need to loop; pte's aren't interested in the
>>>> -                * individual L1 entries.
>>>> +                * With LPAE, we must loop over to map
>>>> +                * all the pmds for the given range.
>>>>                  */
>>>> -               alloc_init_pte(pmd, addr, end, __phys_to_pfn(phys), type);
>>>> -       }
>>>> +               next = pmd_addr_end(addr, end);
>>>> +
>>>> +               /*
>>>> +                * Try a section mapping - addr, next and phys must all be
>>>> +                * aligned to a section boundary.
>>>> +                */
>>>> +               if (type->prot_sect &&
>>>> +                               ((addr | next | phys) & ~SECTION_MASK) == 0) {
>>>> +                       map_init_section(pmd, addr, next, phys, type);
>>>> +               } else {
>>>> +                       alloc_init_pte(pmd, addr, next,
>>>> +                                               __phys_to_pfn(phys), type);
>>>> +               }
>>>> +
>>>> +               phys += next - addr;
>>>> +
>>>> +       } while (pmd++, addr = next, addr != end);
>>>>  }
>>>>
>>>>  static void __init alloc_init_pud(pgd_t *pgd, unsigned long addr,
>>>> @@ -641,7 +662,7 @@ static void __init alloc_init_pud(pgd_t *pgd, unsigned long addr,
>>>>
>>>>         do {
>>>>                 next = pud_addr_end(addr, end);
>>>> -               alloc_init_section(pud, addr, next, phys, type);
>>>> +               alloc_init_pmd(pud, addr, next, phys, type);
>>>>                 phys += next - addr;
>>>>         } while (pud++, addr = next, addr != end);
>>>>  }
>>>> --
>>>> 1.7.9.5
>>>>
>>> Acked-by: Christoffer Dall <[email-masked]>
>>
>> I am not able to add this in to the patch system because my login fails.
>> I was trying using the credentials registered with linux-arm-kernel
>>  mailing list. Can you please help me here ?
> 
> The mailing list and my site are two entirely separate and independent
> sites.  In fact now, the mailing list is hosted by a separate
> individual.
   ok, Thanks. Got registered separately now.

Regards,
 Sricharan