Subject: [PATCH v4] ARM: LPAE: Fix mapping in alloc_init_pte for unaligned addresses

From: [email-masked] (R Sricharan)
Date: Mon, 4 Feb 2013 10:14:19 +0530

On Monday 04 February 2013 10:10 AM, R Sricharan wrote:
> Hi Catalin,
>
> [ snip..]
>>
>> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
>> index 9f06102..47154f3 100644
>> --- a/arch/arm/mm/mmu.c
>> +++ b/arch/arm/mm/mmu.c
>> @@ -581,34 +581,36 @@ static void __init alloc_init_section(pud_t
>> *pud, unsigned long addr,
>>                         const struct mem_type *type)
>>   {
>>       pmd_t *pmd = pmd_offset(pud, addr);
>> +    unsigned long next;
>>
>> -    /*
>> -     * 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.
>> -     */
>> -    if (type->prot_sect && ((addr | end | phys) & ~SECTION_MASK) == 0) {
>> -        pmd_t *p = pmd;
>> +    do {
>> +        next = pmd_addr_end(addr, end);
>> +
>> +        /*
>> +         * Try a section mapping - next, 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.
>> +         */
>> +        if (((addr | next | phys) & ~SECTION_MASK) == 0) {
>> +            pmd_t *p = pmd;
>>
>     There is a  need to do page mappings even when all the addresses
>     are aligned. This was added with CMA, which required the initial
>     mappings to be set with 2 level tables.
>
    Sorry, i wanted to ask type->prot_sect is removed here and is that
   intentional?
>>   #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 != next);
>>
>> -        do {
>> -            *pmd = __pmd(phys | type->prot_sect);
>> -            phys += SECTION_SIZE;
>> -        } while (pmd++, addr += SECTION_SIZE, addr != end);
>> -
>> -        flush_pmd_entry(p);
>> -    } else {
>> -        /*
>> -         * No need to loop; pte's aren't interested in the
>> -         * individual L1 entries.
>> -         */
>> -        alloc_init_pte(pmd, addr, end, __phys_to_pfn(phys), type);
>> -    }
>> +            flush_pmd_entry(p);
>> +        } else {
>> +            alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys), type);
>> +            phys += next - addr;
>> +            pmd++;
>> +        }
>> +    } while (addr = next, addr != end);
>>   }
>>
>>   static void __init alloc_init_pud(pgd_t *pgd, unsigned long addr,
>>
   I did a similar kind of patch in my V1 [1].
    I should be using PMD_MASK instead of SECTION_MASK there, and
   updated it in the next version.

    [1] https://patchwork.kernel.org/patch/1272991/

Regards,
   Sricharan