[PATCH 4.4 13/50] s390/dasd: fix diag 0x250 inline assembly

From: Greg Kroah-Hartman
Date: Mon Mar 14 2016 - 14:01:30 EST

4.4-stable review patch. If anyone has any objections, please let me know.


From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>

commit ce0c12b633846a47e103842149a5bac2e5d261ec upstream.

git commit 1ec2772e0c3c ("s390/diag: add a statistic for diagnose
calls") added function calls to gather diagnose statistics.

In case of the dasd diag driver the function call was added between a
register asm statement which initialized register r2 and the inline
assembly itself. The function call clobbers the contents of register
r2 and therefore the diag 0x250 call behaves in a more or less random

Fix this by extracting the function call into a separate function like
we do everywhere else.

Fixes: 1ec2772e0c3c ("s390/diag: add a statistic for diagnose calls")
Reported-and-tested-by: Stefan Haberland <sth@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/s390/block/dasd_diag.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

--- a/drivers/s390/block/dasd_diag.c
+++ b/drivers/s390/block/dasd_diag.c
@@ -67,7 +67,7 @@ static const u8 DASD_DIAG_CMS1[] = { 0xc
* and function code cmd.
* In case of an exception return 3. Otherwise return result of bitwise OR of
* resulting condition code and DIAG return code. */
-static inline int dia250(void *iob, int cmd)
+static inline int __dia250(void *iob, int cmd)
register unsigned long reg2 asm ("2") = (unsigned long) iob;
typedef union {
@@ -77,7 +77,6 @@ static inline int dia250(void *iob, int
int rc;

rc = 3;
- diag_stat_inc(DIAG_STAT_X250);
asm volatile(
" diag 2,%2,0x250\n"
"0: ipm %0\n"
@@ -91,6 +90,12 @@ static inline int dia250(void *iob, int
return rc;

+static inline int dia250(void *iob, int cmd)
+ diag_stat_inc(DIAG_STAT_X250);
+ return __dia250(iob, cmd);
/* Initialize block I/O to DIAG device using the specified blocksize and
* block offset. On success, return zero and set end_block to contain the
* number of blocks on the device minus the specified offset. Return non-zero