sh: Migrate from PG_mapped to PG_dcache_dirty.

This inverts the delayed dcache flush a bit to be more in line with other
platforms. At the same time this also gives us the ability to do some
more optimizations and cleanup. Now that the update_mmu_cache() callsite
only tests for the bit, the implementation can gradually be split out and
made generic, rather than relying on special implementations for each of
the peculiar CPU types.

SH7705 in 32kB mode and SH-4 still need slightly different handling, but
this is something that can remain isolated in the varying page copy/clear
routines. On top of that, SH-X3 is dcache coherent, so there is no need
to bother with any of these tests in the PTEAEX version of
update_mmu_cache(), so we kill that off too.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 9 insertions, 1 deletions

diff --git a/arch/sh/mm/cache-sh4.c b/arch/sh/mm/cache-sh4.c
index 5cfe08dbb59..c3a09b27f8d 100644
--- a/arch/sh/mm/cache-sh4.c
+++ b/arch/sh/mm/cache-sh4.c
@@ -14,6 +14,7 @@
 #include <linux/mm.h>
 #include <linux/io.h>
 #include <linux/mutex.h>
+#include <linux/fs.h>
 #include <asm/mmu_context.h>
 #include <asm/cacheflush.h>
 
@@ -246,7 +247,14 @@ static inline void flush_cache_4096(unsigned long start,
  */
 void flush_dcache_page(struct page *page)
 {
-	if (test_bit(PG_mapped, &page->flags)) {
+	struct address_space *mapping = page_mapping(page);
+
+#ifndef CONFIG_SMP
+	if (mapping && !mapping_mapped(mapping))
+		set_bit(PG_dcache_dirty, &page->flags);
+	else
+#endif
+	{
 		unsigned long phys = PHYSADDR(page_address(page));
 		unsigned long addr = CACHE_OC_ADDRESS_ARRAY;
 		int i, n;