asm-generic: uaccess: Allow arches to over-ride __{get,put}_user_fn()

As of now these default to calling the arch provided __copy_{to,from}_user()
routines which being general purpose (w.r.t buffer alignment and lengths)
would lead to alignment checks in generated code (for arches which don't
support unaligned load/stores).

Given that in this case we already know that data involved is "unit"
sized and aligned, using the vanilla copy backend is a bit wasteful.

This change thus allows arches to over-ride the aforementioned routines.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index 5f6ee6138f9a..c184aa8ec8cd 100644
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -169,12 +169,18 @@ static inline __must_check long __copy_to_user(void __user *to,
                 -EFAULT;                                        \
 })
 
+#ifndef __put_user_fn
+
 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
 {
         size = __copy_to_user(ptr, x, size);
         return size ? -EFAULT : size;
 }
 
+#define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k)
+
+#endif
+
 extern int __put_user_bad(void) __attribute__((noreturn));
 
 #define __get_user(x, ptr)                                      \
@@ -225,12 +231,17 @@ extern int __put_user_bad(void) __attribute__((noreturn));
                 -EFAULT;                                        \
 })
 
+#ifndef __get_user_fn
 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 {
         size = __copy_from_user(x, ptr, size);
         return size ? -EFAULT : size;
 }
 
+#define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k)
+
+#endif
+
 extern int __get_user_bad(void) __attribute__((noreturn));
 
 #ifndef __copy_from_user_inatomic