[PATCH v2 02/12] s390/percpu: Add sanity check to GEN_MVIY macro

[Heiko Carstens <hca@linux.ibm.com>]

Emit an error if the GEN_MVIY macro fails to parse the passed register
string. This will make it more obvious if something similar which was
fixed with [1] happens again.

[1] commit 101782f8945a ("s390/percpu: Fix MVIY_PERCPU() with older binutils")

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
 arch/s390/include/asm/percpu.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h
index 31012abe8292..9888b38dedab 100644
--- a/arch/s390/include/asm/percpu.h
+++ b/arch/s390/include/asm/percpu.h
@@ -100,12 +100,17 @@
  */
 
 #define MVIY_PERCPU(disp, dispalt, reg)						\
-	".macro GEN_MVIY disp reg\n"						\
+	".macro GEN_MVIY disp, reg\n"						\
+	".set	.Lreg,255\n"							\
 	".irp	rs,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15\n"			\
 	"	.ifc \\reg,%%r\\rs\n"						\
-	"	mviy	\\disp(%%r0),\\rs\n"					\
+	"		.set	.Lreg,\\rs\n"					\
 	"	.endif\n"							\
 	".endr\n"								\
+	".if .Lreg == 255\n"							\
+	"	.error \"Illegal register number\"\n"				\
+	".endif\n"								\
+	"mviy	\\disp(%%r0),.Lreg\n"						\
 	".endm\n"								\
 	ALTERNATIVE("GEN_MVIY " disp    ", " reg "\n",				\
 		    "GEN_MVIY " dispalt ", " reg "\n",				\
-- 
2.53.0