From: Heiko Carstens <hca@linux.ibm.com>
Date: Tue, 2 Feb 2021 15:45:37 +0000 (+0100)
Subject: s390/vtime: fix inline assembly clobber list
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=b29c5093820d333eef22f58cd04ec0d089059c39;p=linux.git

s390/vtime: fix inline assembly clobber list

The stck/stckf instruction used within the inline assembly within
do_account_vtime() changes the condition code. This is not reflected
with the clobber list, and therefore might result in incorrect code
generation.

It seems unlikely that the compiler could generate incorrect code
considering the surrounding C code, but it must still be fixed.

Cc: <stable@vger.kernel.org>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
---

diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 5aaa2ca6a9286..978a35ea6081f 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -136,7 +136,8 @@ static int do_account_vtime(struct task_struct *tsk)
 		"	stck	%1"	/* Store current tod clock value */
 #endif
 		: "=Q" (S390_lowcore.last_update_timer),
-		  "=Q" (S390_lowcore.last_update_clock));
+		  "=Q" (S390_lowcore.last_update_clock)
+		: : "cc");
 	clock = S390_lowcore.last_update_clock - clock;
 	timer -= S390_lowcore.last_update_timer;