s390/traps: get rid of magic cast for program interruption code

Add a proper union in lowcore to reflect architecture and get rid of a
"magic" cast in order to read the full program interruption code.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Author: hcahca

arch/s390/include/asm/lowcore.h

@@ -34,8 +34,13 @@ struct lowcore {
 		__u32 ext_int_code_addr;
 	};
 	__u32	svc_int_code;			/* 0x0088 */
-	__u16	pgm_ilc;			/* 0x008c */
-	__u16	pgm_code;			/* 0x008e */
+	union {
+		struct {
+			__u16	pgm_ilc;	/* 0x008c */
+			__u16	pgm_code;	/* 0x008e */
+		};
+		__u32 pgm_int_code;
+	};
 	__u32	data_exc_code;			/* 0x0090 */
 	__u16	mon_class_num;			/* 0x0094 */
 	__u8	per_code;			/* 0x0096 */

arch/s390/kernel/traps.c

@@ -297,7 +297,7 @@ void noinstr __do_pgm_check(struct pt_regs *regs)
 	unsigned int trapnr;
 	irqentry_state_t state;
 
-	regs->int_code = *(u32 *)&S390_lowcore.pgm_ilc;
+	regs->int_code = S390_lowcore.pgm_int_code;
 	regs->int_parm_long = S390_lowcore.trans_exc_code;
 
 	state = irqentry_enter(regs);