From: Vineet Gupta <vgupta@synopsys.com>
Date: Thu, 9 May 2013 16:24:51 +0000 (+0530)
Subject: ARC: [mm] Aliasing VIPT dcache support 2/4
X-Git-Tag: v3.10-rc1~16^2~3
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4102b53392d6397d80b6e09b516517efacf7ea77;p=pandora-kernel.git

ARC: [mm] Aliasing VIPT dcache support 2/4

This is the meat of the series which prevents any dcache alias creation
by always keeping the U and K mapping of a page congruent.
If a mapping already exists, and other tries to access the page, prev
one is flushed to physical page (wback+inv)

Essentially flush_dcache_page()/copy_user_highpage() create K-mapping
of a page, but try to defer flushing, unless U-mapping exist.
When page is actually mapped to userspace, update_mmu_cache() flushes
the K-mapping (in certain cases this can be optimised out)

Additonally flush_cache_mm(), flush_cache_range(), flush_cache_page()
handle the puring of stale userspace mappings on exit/munmap...

flush_anon_page() handles the existing U-mapping for anon page before
kernel reads it via the GUP path.

Note that while not complete, this is enough to boot a simple
dynamically linked Busybox based rootfs

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
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