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s390/vtime: fix inline assembly clobber list

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commit b29c509382 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Heiko Carstens 2021-02-02 16:45:37 +01:00 committed by Greg Kroah-Hartman
parent 13fb0e1ecf
commit 93c5029fb8
1 changed files with 2 additions and 1 deletions
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3
arch/s390/kernel/vtime.c
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@ -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;