v4.19.13 snapshot.
diff --git a/arch/s390/kernel/idle.c b/arch/s390/kernel/idle.c
new file mode 100644
index 0000000..b9d8fe4
--- /dev/null
+++ b/arch/s390/kernel/idle.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Idle functions for s390.
+ *
+ * Copyright IBM Corp. 2014
+ *
+ * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/kernel_stat.h>
+#include <linux/kprobes.h>
+#include <linux/notifier.h>
+#include <linux/init.h>
+#include <linux/cpu.h>
+#include <linux/sched/cputime.h>
+#include <asm/nmi.h>
+#include <asm/smp.h>
+#include "entry.h"
+
+static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
+
+void enabled_wait(void)
+{
+ struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
+ unsigned long long idle_time;
+ unsigned long psw_mask;
+
+ trace_hardirqs_on();
+
+ /* Wait for external, I/O or machine check interrupt. */
+ psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT | PSW_MASK_DAT |
+ PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
+ clear_cpu_flag(CIF_NOHZ_DELAY);
+
+ /* Call the assembler magic in entry.S */
+ psw_idle(idle, psw_mask);
+
+ trace_hardirqs_off();
+
+ /* Account time spent with enabled wait psw loaded as idle time. */
+ write_seqcount_begin(&idle->seqcount);
+ idle_time = idle->clock_idle_exit - idle->clock_idle_enter;
+ idle->clock_idle_enter = idle->clock_idle_exit = 0ULL;
+ idle->idle_time += idle_time;
+ idle->idle_count++;
+ account_idle_time(cputime_to_nsecs(idle_time));
+ write_seqcount_end(&idle->seqcount);
+}
+NOKPROBE_SYMBOL(enabled_wait);
+
+static ssize_t show_idle_count(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
+ unsigned long long idle_count;
+ unsigned int seq;
+
+ do {
+ seq = read_seqcount_begin(&idle->seqcount);
+ idle_count = READ_ONCE(idle->idle_count);
+ if (READ_ONCE(idle->clock_idle_enter))
+ idle_count++;
+ } while (read_seqcount_retry(&idle->seqcount, seq));
+ return sprintf(buf, "%llu\n", idle_count);
+}
+DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
+
+static ssize_t show_idle_time(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
+ unsigned long long now, idle_time, idle_enter, idle_exit;
+ unsigned int seq;
+
+ do {
+ now = get_tod_clock();
+ seq = read_seqcount_begin(&idle->seqcount);
+ idle_time = READ_ONCE(idle->idle_time);
+ idle_enter = READ_ONCE(idle->clock_idle_enter);
+ idle_exit = READ_ONCE(idle->clock_idle_exit);
+ } while (read_seqcount_retry(&idle->seqcount, seq));
+ idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0;
+ return sprintf(buf, "%llu\n", idle_time >> 12);
+}
+DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
+
+u64 arch_cpu_idle_time(int cpu)
+{
+ struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
+ unsigned long long now, idle_enter, idle_exit;
+ unsigned int seq;
+
+ do {
+ now = get_tod_clock();
+ seq = read_seqcount_begin(&idle->seqcount);
+ idle_enter = READ_ONCE(idle->clock_idle_enter);
+ idle_exit = READ_ONCE(idle->clock_idle_exit);
+ } while (read_seqcount_retry(&idle->seqcount, seq));
+
+ return cputime_to_nsecs(idle_enter ? ((idle_exit ?: now) - idle_enter) : 0);
+}
+
+void arch_cpu_idle_enter(void)
+{
+ local_mcck_disable();
+}
+
+void arch_cpu_idle(void)
+{
+ if (!test_cpu_flag(CIF_MCCK_PENDING))
+ /* Halt the cpu and keep track of cpu time accounting. */
+ enabled_wait();
+ local_irq_enable();
+}
+
+void arch_cpu_idle_exit(void)
+{
+ local_mcck_enable();
+ if (test_cpu_flag(CIF_MCCK_PENDING))
+ s390_handle_mcck();
+}
+
+void arch_cpu_idle_dead(void)
+{
+ cpu_die();
+}