s390/sclp: fix addressing mode clobber

The early mini sclp driver may be called in zArch mode either in
31 or 64 bit addressing mode.
If called in 31 bit addressing mode the new external interrupt psw
however would switch to 64 bit addressing mode. This would cause an
addressing exception within the interrupt handler, since the code
didn't expect the zArch/31 bit addressing mode combination.

Fix this by setting the new psw addressing mode bits so they fit
the current addressing mode.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/sclp.S

@@ -44,6 +44,12 @@ _sclp_wait_int:
 #endif
 	mvc	.LoldpswS1-.LbaseS1(16,%r13),0(%r8)
 	mvc	0(16,%r8),0(%r9)
+#ifdef CONFIG_64BIT
+	epsw	%r6,%r7				# set current addressing mode
+	nill	%r6,0x1				# in new psw (31 or 64 bit mode)
+	nilh	%r7,0x8000
+	stm	%r6,%r7,0(%r8)
+#endif
 	lhi	%r6,0x0200			# cr mask for ext int (cr0.54)
 	ltr	%r2,%r2
 	jz	.LsetctS1
@@ -87,7 +93,7 @@ _sclp_wait_int:
 	.long	0x00080000, 0x80000000+.LwaitS1	# PSW to handle ext int
 #ifdef CONFIG_64BIT
 .LextpswS1_64:
-	.quad	0x0000000180000000, .LwaitS1	# PSW to handle ext int, 64 bit
+	.quad	0, .LwaitS1			# PSW to handle ext int, 64 bit
 #endif
 .LwaitpswS1:
 	.long	0x010a0000, 0x00000000+.LloopS1	# PSW to wait for ext int