linux-kernel - [PATCH v2 18/40] blackfin: fix put

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Date:	Tue, 6 Jan 2015 17:44:31 +0200
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org,
	Steven Miao <realmz6@...il.com>,
	adi-buildroot-devel@...ts.sourceforge.net
Subject: [PATCH v2 18/40] blackfin: fix put_user sparse errors

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 caller
assigns x to typeof(*p), which in turn forces all the necessary type
checks.

Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---
 arch/blackfin/include/asm/uaccess.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/blackfin/include/asm/uaccess.h b/arch/blackfin/include/asm/uaccess.h
index 2dcc930..4bf968c 100644
--- a/arch/blackfin/include/asm/uaccess.h
+++ b/arch/blackfin/include/asm/uaccess.h
@@ -89,10 +89,10 @@ struct exception_table_entry {
 			break;					\
 		case 8: {					\
 			long _xl, _xh;				\
-			_xl = ((long *)&_x)[0];			\
-			_xh = ((long *)&_x)[1];			\
-			__put_user_asm(_xl, ((long __user *)_p)+0, );	\
-			__put_user_asm(_xh, ((long __user *)_p)+1, );	\
+			_xl = ((__force long *)&_x)[0];		\
+			_xh = ((__force long *)&_x)[1];		\
+			__put_user_asm(_xl, ((__force long __user *)_p)+0, );\
+			__put_user_asm(_xh, ((__force long __user *)_p)+1, );\
 		} break;					\
 		default:					\
 			_err = __put_user_bad();		\
-- 
MST

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