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

[R Sricharan]

On Wednesday 06 February 2013 08:46 PM, Catalin Marinas wrote:
> On Wed, Feb 06, 2013 at 01:56:12PM +0000, R Sricharan wrote:
>> On Wednesday 06 February 2013 05:45 PM, Catalin Marinas wrote:
>>> On Mon, Feb 04, 2013 at 04:44:19AM +0000, R Sricharan wrote:
>>>>      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/
>>>
>>> With regards to your current patch, I really don't think looping over
>>> pmd in alloc_init_pte() is the right fix. The alloc_init_pte() function
>>> gets a pmd argument and it is supposed to make it point to a pte and
>>> populate that pte rather than populate a number of pmds.
>>>
>>> create_mapping() loops over pgds. alloc_init_pud() loops over puds
>>> (well, we don't have any but we have the function for consistency).
>>> alloc_init_section() should loop over pmds (we can even change the name
>>> to alloc_init_pmd()).
>>>
>>> Your original patch from August was better as it kept the looping
>>> consistent but as you said, it should be using pmd_addr_end(). We can
>>> use something simpler like alloc_init_pmd() on arm64 and instead of
>>> set_pmd() there just call a separate map_init_section() which for
>>> 2-levels it sets both entries. This may address Russell's comment that
>>> the resulting code was ugly.
>>
>>    Thanks. So just to understand, you mean alloc_init_pmd loops over
>>    map_init_section. map_init_section populates either one pmd
>>    or calls alloc_init_pte. correct ? . I can send a v5 for this.
>
> alloc_init_pmd() loops over pmd (similar to alloc_init_pud). If
> (type->prot_sect && ((addr | next | phys) & ~SECTION_MASK) == 0) you
> call a map_init_section (whatever name you think is better) function
> which contains the current section code from alloc_init_section().
> Something like below (easier than explaining):
>
> static void __init map_init_section(pmd_t *pmd, unsigned long addr,
> 				    unsigned long end, phys_addr_t phys,
> 				    const struct mem_type *type)
> {
> #ifndef CONFIG_ARM_LPAE
> 	if (addr & SECTION_SIZE)
> 		pmd++;
> #endif
>
> 	do {
> 		*pmd = __pmd(phys | type->prot_sect);
> 		phys += SECTION_SIZE;
> 	} while (pmd++, addr += SECTION_SIZE, addr != end);
>
> 	flush_pmd_entry(p);
> }
>
> Pretty much avoiding the indentation level in alloc_init_section() with
> multiple loops.
Thanks for explaining. will post V5 for this.

Regards,
  Sricharan