[PATCH 4.9 29/62] s390/uaccess: avoid (false positive) compiler warnings

Greg Kroah-Hartman
2019-11-04T22:27:24Z

From: Christian Borntraeger <borntraeger@de.ibm.com>

[ Upstream commit 062795fcdcb2d22822fb42644b1d76a8ad8439b3 ]

Depending on inlining decisions by the compiler, __get/put_user_fn
might become out of line. Then the compiler is no longer able to tell
that size can only be 1,2,4 or 8 due to the check in __get/put_user
resulting in false positives like

./arch/s390/include/asm/uaccess.h: In function ‘__put_user_fn’:
./arch/s390/include/asm/uaccess.h:113:9: warning: ‘rc’ may be used uninitialized in this function [-Wmaybe-uninitialized]
113 | return rc;
| ^~
./arch/s390/include/asm/uaccess.h: In function ‘__get_user_fn’:
./arch/s390/include/asm/uaccess.h:143:9: warning: ‘rc’ may be used uninitialized in this function [-Wmaybe-uninitialized]
143 | return rc;
| ^~

These functions are supposed to be always inlined. Mark it as such.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/include/asm/uaccess.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index a7ef702201260..31b2913372b56 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -151,7 +151,7 @@ unsigned long __must_check __copy_to_user(void __user *to, const void *from,
__rc; \
})

-static inline int __put_user_fn(void *x, void __user *ptr, unsigned long size)
+static __always_inline int __put_user_fn(void *x, void __user *ptr, unsigned long size)
{
unsigned long spec = 0x810000UL;
int rc;
@@ -181,7 +181,7 @@ static inline int __put_user_fn(void *x, void __user *ptr, unsigned long size)
return rc;
}

-static inline int __get_user_fn(void *x, const void __user *ptr, unsigned long size)
+static __always_inline int __get_user_fn(void *x, const void __user *ptr, unsigned long size)
{
unsigned long spec = 0x81UL;
int rc;
--
2.20.1