• Haavard Skinnemoen's avatar
    [PATCH] Generic ioremap_page_range: flush_cache_vmap · db71daab
    Haavard Skinnemoen authored
    
    
    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: default avatarHaavard 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: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    db71daab