Thread (84 messages) 84 messages, 14 authors, 2015-01-27
STALE4192d

[PATCH v2 19/40] ia64: fix put_user sparse errors

From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2015-01-06 15:44:46
Also in: lkml
Subsystem: the rest · Maintainer: Linus Torvalds

virtio wants to write bitwise types to userspace using put_user.
At the moment this triggers sparse errors, since the value is passed
through an integer.

For example:

	__le32 __user *p;
	__le32 x;
	put_user(x, p);

is safe, but currently triggers a sparse warning.

Fix that up using __force.

Note: this does not suppress any useful sparse checks since callers
do a cast (__typeof__(*(ptr))) (x) which in turn forces all the
necessary type checks.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 arch/ia64/include/asm/uaccess.h | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/ia64/include/asm/uaccess.h b/arch/ia64/include/asm/uaccess.h
index 967c312..4f3fb6cc 100644
--- a/arch/ia64/include/asm/uaccess.h
+++ b/arch/ia64/include/asm/uaccess.h
@@ -169,10 +169,11 @@ do {									\
 	(err) = ia64_getreg(_IA64_REG_R8);				\
 	(val) = ia64_getreg(_IA64_REG_R9);				\
 } while (0)
-# define __put_user_size(val, addr, n, err)							\
-do {												\
-	__st_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE, (unsigned long) (val));	\
-	(err) = ia64_getreg(_IA64_REG_R8);							\
+# define __put_user_size(val, addr, n, err)				\
+do {									\
+	__st_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE,	\
+		  (__force unsigned long) (val));			\
+	(err) = ia64_getreg(_IA64_REG_R8);				\
 } while (0)
 #endif /* !ASM_SUPPORTED */
 
-- 
MST
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