Re: [PATCH 1/1] arm64: fix flush_cache_range

From: Catalin Marinas
Date: Thu May 26 2016 - 12:45:09 EST

On Wed, May 25, 2016 at 06:27:07PM +0100, Russell King - ARM Linux wrote:
> On Wed, May 25, 2016 at 04:22:55PM +0100, Catalin Marinas wrote:
> > That's when we realised that the CoW problem no longer exists for
> > non-aliasing VIPT caches. However, the I-cache counterpart 6060e8df5178
> > has not been reverted.
> I think I mostly agree, except for reverting 6060e8df5178, which I don't
> think would be correct. That reintroduces the possibility of flushing
> the I-cache twice in that path, once for aliasing vipt dcaches, and again
> for asid tagged vivt icaches. I'd rather have the code structured so we
> only do this once.

__sync_icache_dcache() seems to take care of AIVIVT caches as well (i.e.
it invalidates the whole I-cache) so I think we could just remove the
__flush_icache_all() from flush_cache_range().

I can't find a scenario where we still need D-cache clean+invalidate in
flush_cache_range() for aliasing VIPT. As for the I-cache,
__sync_icache_dcache() takes care of all the aliases.