sh: Wire up clear_user_highpage().

With the kmap_coherent() API in place, this is trivial to implement,
and lets us avoid the cache flush in certain cases.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/mm/pg-sh4.c

@@ -9,6 +9,8 @@
 #include <linux/mm.h>
 #include <linux/mutex.h>
 #include <linux/fs.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
 #include <asm/mmu_context.h>
 #include <asm/cacheflush.h>
 
@@ -79,6 +81,27 @@ void copy_user_page(void *to, void *from, unsigned long address,
 	}
 }
 
+void copy_user_highpage(struct page *to, struct page *from,
+			unsigned long vaddr, struct vm_area_struct *vma)
+{
+	void *vfrom, *vto;
+
+	__set_bit(PG_mapped, &to->flags);
+
+	vto = kmap_atomic(to, KM_USER1);
+	vfrom = kmap_coherent(from, vaddr);
+	copy_page(vto, vfrom);
+	kunmap_coherent(vfrom);
+
+	if (((vaddr ^ (unsigned long)vto) & CACHE_ALIAS))
+		__flush_wback_region(vto, PAGE_SIZE);
+
+	kunmap_atomic(vto, KM_USER1);
+	/* Make sure this page is cleared on other CPU's too before using it */
+	smp_wmb();
+}
+EXPORT_SYMBOL(copy_user_highpage);
+
 /*
  * For SH-4, we have our own implementation for ptep_get_and_clear
  */

include/asm-sh/page.h

@@ -73,10 +73,16 @@ extern void copy_page_nommu(void *to, void *from);
 #if !defined(CONFIG_CACHE_OFF) && defined(CONFIG_MMU) && \
 	(defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB))
 struct page;
+struct vm_area_struct;
 extern void clear_user_page(void *to, unsigned long address, struct page *pg);
 extern void copy_user_page(void *to, void *from, unsigned long address, struct page *pg);
 extern void __clear_user_page(void *to, void *orig_to);
 extern void __copy_user_page(void *to, void *from, void *orig_to);
+#ifdef CONFIG_CPU_SH4
+extern void copy_user_highpage(struct page *to, struct page *from,
+			       unsigned long vaddr, struct vm_area_struct *vma);
+#define __HAVE_ARCH_COPY_USER_HIGHPAGE
+#endif
 #else
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)