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

On Sun, Jul 22, 2012 at 5:09 PM, Will Deacon [off-list ref] wrote:

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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 <redacted>

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

Thanks,
Uros.