linux-kernel - [PATCH v2 06/76] asm-generic: uaccess: Allow arches to over-ride __{get,put}_user

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Date:	Fri, 18 Jan 2013 17:54:20 +0530
From:	Vineet Gupta <Vineet.Gupta1@...opsys.com>
To:	<linux-arch@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:	<arnd@...db.de>, Vineet Gupta <Vineet.Gupta1@...opsys.com>
Subject: [PATCH v2 06/76] 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@...opsys.com>
Acked-by: Arnd Bergmann <arnd@...db.de>
---
 include/asm-generic/uaccess.h |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index 5f6ee61..c184aa8 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
-- 
1.7.4.1

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