[PATCH] ARM: mm: avoid attempting to flush the gate_vma with VIVT caches

[ubizjak@gmail.com (Uros Bizjak)]

On Sun, Jul 22, 2012 at 5:09 PM, Will Deacon <will.deacon@arm.com> wrote:
>> >>>> It may be writable, but we never actually write to it after it has been
>> >>>> initialised so there's no need to worry about caching issues (the cache is
>> >>>> flushed in devicemaps_init).
>> >>>
>> >>> Except if CONFIG_TLS_REG_EMUL is enabled
>> >>
>> >> is disabled I mean.
>> >
>> > Well spotted! I disagree about the address being flushed though -- it looks
>> > to me like we flush from 0xffff0000 - 0xffff1000, which is what we want. Why
>> > do you think we're flushing from the linear mapping?
>>
>> I do not think we're flushing from the linear mapping, I believe the
>> address used by the elf_core_dump function (elf_core_dump -> kmap ->
>> page_address), to copy the page data to the core is the linear mapping
>> address, which is the reason why we need the flush at all.
>
> Ok, good, sounds like we're singing the same tune at last. If you're happy
> with my proposed change to the original patch and Uros could re-test, then I
> think we're in business again.

The updated patch is effectively the same as the patch at [1], which
works for our target as well. This patch was also tested on 3.4
branch, where it fixes the same problem.

For the patch, I can add:

Tested-by: Uros Bizjak <ubizjak@gmail.com>

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2012-June/105047.html

Thanks,
Uros.