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

From: [email-masked] (Sricharan R)
Date: Mon, 18 Mar 2013 11:20:47 +0530

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 ?

Regards,
 Sricharan