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Subject[PATCH 2/8] asm-generic: improve the nommu {get,put}_user handling
Date
Instead of reusing raw_{copy,to}_from_user implement separate handlers
using {get,put}_unaligned. This ensures unaligned access is handled
correctly, and avoid the need for the small constant size optimization
in raw_{copy,to}_from_user.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
include/asm-generic/uaccess.h | 91 ++++++++++++++++++++---------------
1 file changed, 51 insertions(+), 40 deletions(-)

diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index ba68ee4dabfaa7..6de5f524e9e631 100644
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -10,28 +10,60 @@
#include <linux/string.h>

#ifdef CONFIG_UACCESS_MEMCPY
-static inline __must_check unsigned long
-raw_copy_from_user(void *to, const void __user * from, unsigned long n)
+#include <asm/unaligned.h>
+
+static inline int __get_user_fn(size_t size, const void __user *from, void *to)
{
- if (__builtin_constant_p(n)) {
- switch(n) {
- case 1:
- *(u8 *)to = *(u8 __force *)from;
- return 0;
- case 2:
- *(u16 *)to = *(u16 __force *)from;
- return 0;
- case 4:
- *(u32 *)to = *(u32 __force *)from;
- return 0;
-#ifdef CONFIG_64BIT
- case 8:
- *(u64 *)to = *(u64 __force *)from;
- return 0;
-#endif
- }
+ BUILD_BUG_ON(!__builtin_constant_p(size));
+
+ switch (size) {
+ case 1:
+ *(u8 *)to = get_unaligned((u8 __force *)from);
+ return 0;
+ case 2:
+ *(u16 *)to = get_unaligned((u16 __force *)from);
+ return 0;
+ case 4:
+ *(u32 *)to = get_unaligned((u32 __force *)from);
+ return 0;
+ case 8:
+ *(u64 *)to = get_unaligned((u64 __force *)from);
+ return 0;
+ default:
+ BUILD_BUG();
+ return 0;
+ }
+
+}
+#define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k)
+
+static inline int __put_user_fn(size_t size, void __user *to, void *from)
+{
+ BUILD_BUG_ON(!__builtin_constant_p(size));
+
+ switch (size) {
+ case 1:
+ put_unaligned(*(u8 *)from, (u8 __force *)to);
+ return 0;
+ case 2:
+ put_unaligned(*(u16 *)from, (u16 __force *)to);
+ return 0;
+ case 4:
+ put_unaligned(*(u32 *)from, (u32 __force *)to);
+ return 0;
+ case 8:
+ put_unaligned(*(u64 *)from, (u64 __force *)to);
+ return 0;
+ default:
+ BUILD_BUG();
+ return 0;
}
+}
+#define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k)

+static inline __must_check unsigned long
+raw_copy_from_user(void *to, const void __user * from, unsigned long n)
+{
memcpy(to, (const void __force *)from, n);
return 0;
}
@@ -39,27 +71,6 @@ raw_copy_from_user(void *to, const void __user * from, unsigned long n)
static inline __must_check unsigned long
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
- if (__builtin_constant_p(n)) {
- switch(n) {
- case 1:
- *(u8 __force *)to = *(u8 *)from;
- return 0;
- case 2:
- *(u16 __force *)to = *(u16 *)from;
- return 0;
- case 4:
- *(u32 __force *)to = *(u32 *)from;
- return 0;
-#ifdef CONFIG_64BIT
- case 8:
- *(u64 __force *)to = *(u64 *)from;
- return 0;
-#endif
- default:
- break;
- }
- }
-
memcpy((void __force *)to, from, n);
return 0;
}
--
2.28.0
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