s390: add trace events for idle enter/exit

Helpful for debugging.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/kernel/idle.c

@@ -14,6 +14,7 @@
 #include <linux/init.h>
 #include <linux/cpu.h>
 #include <linux/sched/cputime.h>
+#include <trace/events/power.h>
 #include <asm/nmi.h>
 #include <asm/smp.h>
 #include "entry.h"
@@ -32,11 +33,12 @@ void enabled_wait(void)
 		PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 	clear_cpu_flag(CIF_NOHZ_DELAY);
 
+	trace_cpu_idle_rcuidle(1, smp_processor_id());
 	local_irq_save(flags);
 	/* Call the assembler magic in entry.S */
 	psw_idle(idle, psw_mask);
 	local_irq_restore(flags);
-
+	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
 
 	/* Account time spent with enabled wait psw loaded as idle time. */
 	write_seqcount_begin(&idle->seqcount);