[S390] kprobes: forbid probing of stnsm/stosm/epsw

The probed instructions will be executed in a single stepped and irq
disabled context. Therefore the results of stnsm, stosm and epsw would
be wrong if probed.
So let's just disallow probing of these functions. If really needed a
fixup could be written for each of them, but I doubt it's worth it.

Signed-off-by: Heiko Carstens <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

arch/s390/kernel/kprobes.c

···
 	case 0x0b:	/* bsm	 */
 	case 0x83:	/* diag  */
 	case 0x44:	/* ex	 */
+	case 0xac:	/* stnsm */
+	case 0xad:	/* stosm */
 		return -EINVAL;
 	}
 	switch (*(__u16 *) instruction) {
···
 	case 0xb258:	/* bsg	 */
 	case 0xb218:	/* pc	 */
 	case 0xb228:	/* pt	 */
+	case 0xb98d:	/* epsw	 */
 		return -EINVAL;
 	}
 	return 0;