[ARM] copypage: provide our own copy_user_highpage()

We used to override the copy_user_page() function.  However, this
is not only inefficient, it also causes additional complexity for
highmem support, since we convert from a struct page to a kernel
direct mapped address and back to a struct page again.

Moreover, with highmem support, we end up pointlessly setting up
kmap entries for pages which we're going to remap.  So, push the
kmapping down into the copypage implementation files where it's
required.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 14 insertions, 9 deletions

diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h
index bed1c0a0036..1581b8cf8f3 100644
--- a/arch/arm/include/asm/page.h
+++ b/arch/arm/include/asm/page.h
@@ -108,30 +108,35 @@
 #error Unknown user operations model
 #endif
 
+struct page;
+
 struct cpu_user_fns {
 	void (*cpu_clear_user_page)(void *p, unsigned long user);
-	void (*cpu_copy_user_page)(void *to, const void *from,
-				   unsigned long user);
+	void (*cpu_copy_user_highpage)(struct page *to, struct page *from,
+			unsigned long vaddr);
 };
 
 #ifdef MULTI_USER
 extern struct cpu_user_fns cpu_user;
 
-#define __cpu_clear_user_page	cpu_user.cpu_clear_user_page
-#define __cpu_copy_user_page	cpu_user.cpu_copy_user_page
+#define __cpu_clear_user_page		cpu_user.cpu_clear_user_page
+#define __cpu_copy_user_highpage	cpu_user.cpu_copy_user_highpage
 
 #else
 
-#define __cpu_clear_user_page	__glue(_USER,_clear_user_page)
-#define __cpu_copy_user_page	__glue(_USER,_copy_user_page)
+#define __cpu_clear_user_page		__glue(_USER,_clear_user_page)
+#define __cpu_copy_user_highpage	__glue(_USER,_copy_user_highpage)
 
 extern void __cpu_clear_user_page(void *p, unsigned long user);
-extern void __cpu_copy_user_page(void *to, const void *from,
-				 unsigned long user);
+extern void __cpu_copy_user_highpage(struct page *to, struct page *from,
+			unsigned long vaddr);
 #endif
 
 #define clear_user_page(addr,vaddr,pg)	 __cpu_clear_user_page(addr, vaddr)
-#define copy_user_page(to,from,vaddr,pg) __cpu_copy_user_page(to, from, vaddr)
+
+#define __HAVE_ARCH_COPY_USER_HIGHPAGE
+#define copy_user_highpage(to,from,vaddr,vma)	\
+	__cpu_copy_user_highpage(to, from, vaddr)
 
 #define clear_page(page)	memzero((void *)(page), PAGE_SIZE)
 extern void copy_page(void *to, const void *from);