The existing implementation of ioremap_page_range(), which was taken
from i386, does this:

	flush_cache_all();
	/* modify page tables */
	flush_tlb_all();

I think this is a bit defensive, so this patch changes the generic
implementation to do:

	/* modify page tables */
	flush_cache_vmap(start, end);

instead, which is similar to what vmalloc() does. This should still
be correct because we never modify existing PTEs. According to
James Bottomley:

The problem the flush_tlb_all() is trying to solve is to avoid stale tlb
entries in the ioremap area.  We're just being conservative by flushing
on both map and unmap.  Technically what vmalloc/vfree does (only flush
the tlb on unmap) is just fine because it means that the only tlb
entries in the remap area must belong to in-use mappings.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Andi Kleen <ak@suse.de>
Cc: <linux-m32r@ml.linux-m32r.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>