[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 bed1c0a00368..1581b8cf8f33 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);