Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1015 insertions, 0 deletions

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
new file mode 100644
index 000000000..a9530e866
--- /dev/null
+++ b/kernel/time/tick-broadcast.c
@@ -0,0 +1,1015 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file contains functions which emulate a local clock-event
+ * device via a broadcast event source.
+ *
+ * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
+ * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
+ * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
+ */
+#include <linux/cpu.h>
+#include <linux/err.h>
+#include <linux/hrtimer.h>
+#include <linux/interrupt.h>
+#include <linux/percpu.h>
+#include <linux/profile.h>
+#include <linux/sched.h>
+#include <linux/smp.h>
+#include <linux/module.h>
+
+#include "tick-internal.h"
+
+/*
+ * Broadcast support for broken x86 hardware, where the local apic
+ * timer stops in C3 state.
+ */
+
+static struct tick_device tick_broadcast_device;
+static cpumask_var_t tick_broadcast_mask __cpumask_var_read_mostly;
+static cpumask_var_t tick_broadcast_on __cpumask_var_read_mostly;
+static cpumask_var_t tmpmask __cpumask_var_read_mostly;
+static int tick_broadcast_forced;
+
+static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
+
+#ifdef CONFIG_TICK_ONESHOT
+static void tick_broadcast_setup_oneshot(struct clock_event_device *bc);
+static void tick_broadcast_clear_oneshot(int cpu);
+static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
+# ifdef CONFIG_HOTPLUG_CPU
+static void tick_broadcast_oneshot_offline(unsigned int cpu);
+# endif
+#else
+static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { BUG(); }
+static inline void tick_broadcast_clear_oneshot(int cpu) { }
+static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
+# ifdef CONFIG_HOTPLUG_CPU
+static inline void tick_broadcast_oneshot_offline(unsigned int cpu) { }
+# endif
+#endif
+
+/*
+ * Debugging: see timer_list.c
+ */
+struct tick_device *tick_get_broadcast_device(void)
+{
+	return &tick_broadcast_device;
+}
+
+struct cpumask *tick_get_broadcast_mask(void)
+{
+	return tick_broadcast_mask;
+}
+
+/*
+ * Start the device in periodic mode
+ */
+static void tick_broadcast_start_periodic(struct clock_event_device *bc)
+{
+	if (bc)
+		tick_setup_periodic(bc, 1);
+}
+
+/*
+ * Check, if the device can be utilized as broadcast device:
+ */
+static bool tick_check_broadcast_device(struct clock_event_device *curdev,
+					struct clock_event_device *newdev)
+{
+	if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
+	    (newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
+	    (newdev->features & CLOCK_EVT_FEAT_C3STOP))
+		return false;
+
+	if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
+	    !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
+		return false;
+
+	return !curdev || newdev->rating > curdev->rating;
+}
+
+/*
+ * Conditionally install/replace broadcast device
+ */
+void tick_install_broadcast_device(struct clock_event_device *dev)
+{
+	struct clock_event_device *cur = tick_broadcast_device.evtdev;
+
+	if (!tick_check_broadcast_device(cur, dev))
+		return;
+
+	if (!try_module_get(dev->owner))
+		return;
+
+	clockevents_exchange_device(cur, dev);
+	if (cur)
+		cur->event_handler = clockevents_handle_noop;
+	tick_broadcast_device.evtdev = dev;
+	if (!cpumask_empty(tick_broadcast_mask))
+		tick_broadcast_start_periodic(dev);
+	/*
+	 * Inform all cpus about this. We might be in a situation
+	 * where we did not switch to oneshot mode because the per cpu
+	 * devices are affected by CLOCK_EVT_FEAT_C3STOP and the lack
+	 * of a oneshot capable broadcast device. Without that
+	 * notification the systems stays stuck in periodic mode
+	 * forever.
+	 */
+	if (dev->features & CLOCK_EVT_FEAT_ONESHOT)
+		tick_clock_notify();
+}
+
+/*
+ * Check, if the device is the broadcast device
+ */
+int tick_is_broadcast_device(struct clock_event_device *dev)
+{
+	return (dev && tick_broadcast_device.evtdev == dev);
+}
+
+int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
+{
+	int ret = -ENODEV;
+
+	if (tick_is_broadcast_device(dev)) {
+		raw_spin_lock(&tick_broadcast_lock);
+		ret = __clockevents_update_freq(dev, freq);
+		raw_spin_unlock(&tick_broadcast_lock);
+	}
+	return ret;
+}
+
+
+static void err_broadcast(const struct cpumask *mask)
+{
+	pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
+}
+
+static void tick_device_setup_broadcast_func(struct clock_event_device *dev)
+{
+	if (!dev->broadcast)
+		dev->broadcast = tick_broadcast;
+	if (!dev->broadcast) {
+		pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
+			     dev->name);
+		dev->broadcast = err_broadcast;
+	}
+}
+
+/*
+ * Check, if the device is disfunctional and a place holder, which
+ * needs to be handled by the broadcast device.
+ */
+int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
+{
+	struct clock_event_device *bc = tick_broadcast_device.evtdev;
+	unsigned long flags;
+	int ret = 0;
+
+	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	/*
+	 * Devices might be registered with both periodic and oneshot
+	 * mode disabled. This signals, that the device needs to be
+	 * operated from the broadcast device and is a placeholder for
+	 * the cpu local device.
+	 */
+	if (!tick_device_is_functional(dev)) {
+		dev->event_handler = tick_handle_periodic;
+		tick_device_setup_broadcast_func(dev);
+		cpumask_set_cpu(cpu, tick_broadcast_mask);
+		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+			tick_broadcast_start_periodic(bc);
+		else
+			tick_broadcast_setup_oneshot(bc);
+		ret = 1;
+	} else {
+		/*
+		 * Clear the broadcast bit for this cpu if the
+		 * device is not power state affected.
+		 */
+		if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
+			cpumask_clear_cpu(cpu, tick_broadcast_mask);
+		else
+			tick_device_setup_broadcast_func(dev);
+
+		/*
+		 * Clear the broadcast bit if the CPU is not in
+		 * periodic broadcast on state.
+		 */
+		if (!cpumask_test_cpu(cpu, tick_broadcast_on))
+			cpumask_clear_cpu(cpu, tick_broadcast_mask);
+
+		switch (tick_broadcast_device.mode) {
+		case TICKDEV_MODE_ONESHOT:
+			/*
+			 * If the system is in oneshot mode we can
+			 * unconditionally clear the oneshot mask bit,
+			 * because the CPU is running and therefore
+			 * not in an idle state which causes the power
+			 * state affected device to stop. Let the
+			 * caller initialize the device.
+			 */
+			tick_broadcast_clear_oneshot(cpu);
+			ret = 0;
+			break;
+
+		case TICKDEV_MODE_PERIODIC:
+			/*
+			 * If the system is in periodic mode, check
+			 * whether the broadcast device can be
+			 * switched off now.
+			 */
+			if (cpumask_empty(tick_broadcast_mask) && bc)
+				clockevents_shutdown(bc);
+			/*
+			 * If we kept the cpu in the broadcast mask,
+			 * tell the caller to leave the per cpu device
+			 * in shutdown state. The periodic interrupt
+			 * is delivered by the broadcast device, if
+			 * the broadcast device exists and is not
+			 * hrtimer based.
+			 */
+			if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER))
+				ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
+			break;
+		default:
+			break;
+		}
+	}
+	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+	return ret;
+}
+
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+int tick_receive_broadcast(void)
+{
+	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
+	struct clock_event_device *evt = td->evtdev;
+
+	if (!evt)
+		return -ENODEV;
+
+	if (!evt->event_handler)
+		return -EINVAL;
+
+	evt->event_handler(evt);
+	return 0;
+}
+#endif
+
+/*
+ * Broadcast the event to the cpus, which are set in the mask (mangled).
+ */
+static bool tick_do_broadcast(struct cpumask *mask)
+{
+	int cpu = smp_processor_id();
+	struct tick_device *td;
+	bool local = false;
+
+	/*
+	 * Check, if the current cpu is in the mask
+	 */
+	if (cpumask_test_cpu(cpu, mask)) {
+		struct clock_event_device *bc = tick_broadcast_device.evtdev;
+
+		cpumask_clear_cpu(cpu, mask);
+		/*
+		 * We only run the local handler, if the broadcast
+		 * device is not hrtimer based. Otherwise we run into
+		 * a hrtimer recursion.
+		 *
+		 * local timer_interrupt()
+		 *   local_handler()
+		 *     expire_hrtimers()
+		 *       bc_handler()
+		 *         local_handler()
+		 *	     expire_hrtimers()
+		 */
+		local = !(bc->features & CLOCK_EVT_FEAT_HRTIMER);
+	}
+
+	if (!cpumask_empty(mask)) {
+		/*
+		 * It might be necessary to actually check whether the devices
+		 * have different broadcast functions. For now, just use the
+		 * one of the first device. This works as long as we have this
+		 * misfeature only on x86 (lapic)
+		 */
+		td = &per_cpu(tick_cpu_device, cpumask_first(mask));
+		td->evtdev->broadcast(mask);
+	}
+	return local;
+}
+
+/*
+ * Periodic broadcast:
+ * - invoke the broadcast handlers
+ */
+static bool tick_do_periodic_broadcast(void)
+{
+	cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
+	return tick_do_broadcast(tmpmask);
+}
+
+/*
+ * Event handler for periodic broadcast ticks
+ */
+static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
+{
+	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
+	bool bc_local;
+
+	raw_spin_lock(&tick_broadcast_lock);
+
+	/* Handle spurious interrupts gracefully */
+	if (clockevent_state_shutdown(tick_broadcast_device.evtdev)) {
+		raw_spin_unlock(&tick_broadcast_lock);
+		return;
+	}
+
+	bc_local = tick_do_periodic_broadcast();
+
+	if (clockevent_state_oneshot(dev)) {
+		ktime_t next = ktime_add_ns(dev->next_event, TICK_NSEC);
+
+		clockevents_program_event(dev, next, true);
+	}
+	raw_spin_unlock(&tick_broadcast_lock);
+
+	/*
+	 * We run the handler of the local cpu after dropping
+	 * tick_broadcast_lock because the handler might deadlock when
+	 * trying to switch to oneshot mode.
+	 */
+	if (bc_local)
+		td->evtdev->event_handler(td->evtdev);
+}
+
+/**
+ * tick_broadcast_control - Enable/disable or force broadcast mode
+ * @mode:	The selected broadcast mode
+ *
+ * Called when the system enters a state where affected tick devices
+ * might stop. Note: TICK_BROADCAST_FORCE cannot be undone.
+ */
+void tick_broadcast_control(enum tick_broadcast_mode mode)
+{
+	struct clock_event_device *bc, *dev;
+	struct tick_device *td;
+	int cpu, bc_stopped;
+	unsigned long flags;
+
+	/* Protects also the local clockevent device. */
+	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
+	td = this_cpu_ptr(&tick_cpu_device);
+	dev = td->evtdev;
+
+	/*
+	 * Is the device not affected by the powerstate ?
+	 */
+	if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
+		goto out;
+
+	if (!tick_device_is_functional(dev))
+		goto out;
+
+	cpu = smp_processor_id();
+	bc = tick_broadcast_device.evtdev;
+	bc_stopped = cpumask_empty(tick_broadcast_mask);
+
+	switch (mode) {
+	case TICK_BROADCAST_FORCE:
+		tick_broadcast_forced = 1;
+		fallthrough;
+	case TICK_BROADCAST_ON:
+		cpumask_set_cpu(cpu, tick_broadcast_on);
+		if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
+			/*
+			 * Only shutdown the cpu local device, if:
+			 *
+			 * - the broadcast device exists
+			 * - the broadcast device is not a hrtimer based one
+			 * - the broadcast device is in periodic mode to
+			 *   avoid a hickup during switch to oneshot mode
+			 */
+			if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER) &&
+			    tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+				clockevents_shutdown(dev);
+		}
+		break;
+
+	case TICK_BROADCAST_OFF:
+		if (tick_broadcast_forced)
+			break;
+		cpumask_clear_cpu(cpu, tick_broadcast_on);
+		if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
+			if (tick_broadcast_device.mode ==
+			    TICKDEV_MODE_PERIODIC)
+				tick_setup_periodic(dev, 0);
+		}
+		break;
+	}
+
+	if (bc) {
+		if (cpumask_empty(tick_broadcast_mask)) {
+			if (!bc_stopped)
+				clockevents_shutdown(bc);
+		} else if (bc_stopped) {
+			if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+				tick_broadcast_start_periodic(bc);
+			else
+				tick_broadcast_setup_oneshot(bc);
+		}
+	}
+out:
+	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+EXPORT_SYMBOL_GPL(tick_broadcast_control);
+
+/*
+ * Set the periodic handler depending on broadcast on/off
+ */
+void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
+{
+	if (!broadcast)
+		dev->event_handler = tick_handle_periodic;
+	else
+		dev->event_handler = tick_handle_periodic_broadcast;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void tick_shutdown_broadcast(void)
+{
+	struct clock_event_device *bc = tick_broadcast_device.evtdev;
+
+	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
+		if (bc && cpumask_empty(tick_broadcast_mask))
+			clockevents_shutdown(bc);
+	}
+}
+
+/*
+ * Remove a CPU from broadcasting
+ */
+void tick_broadcast_offline(unsigned int cpu)
+{
+	raw_spin_lock(&tick_broadcast_lock);
+	cpumask_clear_cpu(cpu, tick_broadcast_mask);
+	cpumask_clear_cpu(cpu, tick_broadcast_on);
+	tick_broadcast_oneshot_offline(cpu);
+	tick_shutdown_broadcast();
+	raw_spin_unlock(&tick_broadcast_lock);
+}
+
+#endif
+
+void tick_suspend_broadcast(void)
+{
+	struct clock_event_device *bc;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	bc = tick_broadcast_device.evtdev;
+	if (bc)
+		clockevents_shutdown(bc);
+
+	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+/*
+ * This is called from tick_resume_local() on a resuming CPU. That's
+ * called from the core resume function, tick_unfreeze() and the magic XEN
+ * resume hackery.
+ *
+ * In none of these cases the broadcast device mode can change and the
+ * bit of the resuming CPU in the broadcast mask is safe as well.
+ */
+bool tick_resume_check_broadcast(void)
+{
+	if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT)
+		return false;
+	else
+		return cpumask_test_cpu(smp_processor_id(), tick_broadcast_mask);
+}
+
+void tick_resume_broadcast(void)
+{
+	struct clock_event_device *bc;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	bc = tick_broadcast_device.evtdev;
+
+	if (bc) {
+		clockevents_tick_resume(bc);
+
+		switch (tick_broadcast_device.mode) {
+		case TICKDEV_MODE_PERIODIC:
+			if (!cpumask_empty(tick_broadcast_mask))
+				tick_broadcast_start_periodic(bc);
+			break;
+		case TICKDEV_MODE_ONESHOT:
+			if (!cpumask_empty(tick_broadcast_mask))
+				tick_resume_broadcast_oneshot(bc);
+			break;
+		}
+	}
+	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+#ifdef CONFIG_TICK_ONESHOT
+
+static cpumask_var_t tick_broadcast_oneshot_mask __cpumask_var_read_mostly;
+static cpumask_var_t tick_broadcast_pending_mask __cpumask_var_read_mostly;
+static cpumask_var_t tick_broadcast_force_mask __cpumask_var_read_mostly;
+
+/*
+ * Exposed for debugging: see timer_list.c
+ */
+struct cpumask *tick_get_broadcast_oneshot_mask(void)
+{
+	return tick_broadcast_oneshot_mask;
+}
+
+/*
+ * Called before going idle with interrupts disabled. Checks whether a
+ * broadcast event from the other core is about to happen. We detected
+ * that in tick_broadcast_oneshot_control(). The callsite can use this
+ * to avoid a deep idle transition as we are about to get the
+ * broadcast IPI right away.
+ */
+int tick_check_broadcast_expired(void)
+{
+	return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask);
+}
+
+/*
+ * Set broadcast interrupt affinity
+ */
+static void tick_broadcast_set_affinity(struct clock_event_device *bc,
+					const struct cpumask *cpumask)
+{
+	if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ))
+		return;
+
+	if (cpumask_equal(bc->cpumask, cpumask))
+		return;
+
+	bc->cpumask = cpumask;
+	irq_set_affinity(bc->irq, bc->cpumask);
+}
+
+static void tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
+				     ktime_t expires)
+{
+	if (!clockevent_state_oneshot(bc))
+		clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
+
+	clockevents_program_event(bc, expires, 1);
+	tick_broadcast_set_affinity(bc, cpumask_of(cpu));
+}
+
+static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
+{
+	clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
+}
+
+/*
+ * Called from irq_enter() when idle was interrupted to reenable the
+ * per cpu device.
+ */
+void tick_check_oneshot_broadcast_this_cpu(void)
+{
+	if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) {
+		struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
+
+		/*
+		 * We might be in the middle of switching over from
+		 * periodic to oneshot. If the CPU has not yet
+		 * switched over, leave the device alone.
+		 */
+		if (td->mode == TICKDEV_MODE_ONESHOT) {
+			clockevents_switch_state(td->evtdev,
+					      CLOCK_EVT_STATE_ONESHOT);
+		}
+	}
+}
+
+/*
+ * Handle oneshot mode broadcasting
+ */
+static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
+{
+	struct tick_device *td;
+	ktime_t now, next_event;
+	int cpu, next_cpu = 0;
+	bool bc_local;
+
+	raw_spin_lock(&tick_broadcast_lock);
+	dev->next_event = KTIME_MAX;
+	next_event = KTIME_MAX;
+	cpumask_clear(tmpmask);
+	now = ktime_get();
+	/* Find all expired events */
+	for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
+		/*
+		 * Required for !SMP because for_each_cpu() reports
+		 * unconditionally CPU0 as set on UP kernels.
+		 */
+		if (!IS_ENABLED(CONFIG_SMP) &&
+		    cpumask_empty(tick_broadcast_oneshot_mask))
+			break;
+
+		td = &per_cpu(tick_cpu_device, cpu);
+		if (td->evtdev->next_event <= now) {
+			cpumask_set_cpu(cpu, tmpmask);
+			/*
+			 * Mark the remote cpu in the pending mask, so
+			 * it can avoid reprogramming the cpu local
+			 * timer in tick_broadcast_oneshot_control().
+			 */
+			cpumask_set_cpu(cpu, tick_broadcast_pending_mask);
+		} else if (td->evtdev->next_event < next_event) {
+			next_event = td->evtdev->next_event;
+			next_cpu = cpu;
+		}
+	}
+
+	/*
+	 * Remove the current cpu from the pending mask. The event is
+	 * delivered immediately in tick_do_broadcast() !
+	 */
+	cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask);
+
+	/* Take care of enforced broadcast requests */
+	cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask);
+	cpumask_clear(tick_broadcast_force_mask);
+
+	/*
+	 * Sanity check. Catch the case where we try to broadcast to
+	 * offline cpus.
+	 */
+	if (WARN_ON_ONCE(!cpumask_subset(tmpmask, cpu_online_mask)))
+		cpumask_and(tmpmask, tmpmask, cpu_online_mask);
+
+	/*
+	 * Wakeup the cpus which have an expired event.
+	 */
+	bc_local = tick_do_broadcast(tmpmask);
+
+	/*
+	 * Two reasons for reprogram:
+	 *
+	 * - The global event did not expire any CPU local
+	 * events. This happens in dyntick mode, as the maximum PIT
+	 * delta is quite small.
+	 *
+	 * - There are pending events on sleeping CPUs which were not
+	 * in the event mask
+	 */
+	if (next_event != KTIME_MAX)
+		tick_broadcast_set_event(dev, next_cpu, next_event);
+
+	raw_spin_unlock(&tick_broadcast_lock);
+
+	if (bc_local) {
+		td = this_cpu_ptr(&tick_cpu_device);
+		td->evtdev->event_handler(td->evtdev);
+	}
+}
+
+static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu)
+{
+	if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER))
+		return 0;
+	if (bc->next_event == KTIME_MAX)
+		return 0;
+	return bc->bound_on == cpu ? -EBUSY : 0;
+}
+
+static void broadcast_shutdown_local(struct clock_event_device *bc,
+				     struct clock_event_device *dev)
+{
+	/*
+	 * For hrtimer based broadcasting we cannot shutdown the cpu
+	 * local device if our own event is the first one to expire or
+	 * if we own the broadcast timer.
+	 */
+	if (bc->features & CLOCK_EVT_FEAT_HRTIMER) {
+		if (broadcast_needs_cpu(bc, smp_processor_id()))
+			return;
+		if (dev->next_event < bc->next_event)
+			return;
+	}
+	clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
+}
+
+int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
+{
+	struct clock_event_device *bc, *dev;
+	int cpu, ret = 0;
+	ktime_t now;
+
+	/*
+	 * If there is no broadcast device, tell the caller not to go
+	 * into deep idle.
+	 */
+	if (!tick_broadcast_device.evtdev)
+		return -EBUSY;
+
+	dev = this_cpu_ptr(&tick_cpu_device)->evtdev;
+
+	raw_spin_lock(&tick_broadcast_lock);
+	bc = tick_broadcast_device.evtdev;
+	cpu = smp_processor_id();
+
+	if (state == TICK_BROADCAST_ENTER) {
+		/*
+		 * If the current CPU owns the hrtimer broadcast
+		 * mechanism, it cannot go deep idle and we do not add
+		 * the CPU to the broadcast mask. We don't have to go
+		 * through the EXIT path as the local timer is not
+		 * shutdown.
+		 */
+		ret = broadcast_needs_cpu(bc, cpu);
+		if (ret)
+			goto out;
+
+		/*
+		 * If the broadcast device is in periodic mode, we
+		 * return.
+		 */
+		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
+			/* If it is a hrtimer based broadcast, return busy */
+			if (bc->features & CLOCK_EVT_FEAT_HRTIMER)
+				ret = -EBUSY;
+			goto out;
+		}
+
+		if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
+			WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
+
+			/* Conditionally shut down the local timer. */
+			broadcast_shutdown_local(bc, dev);
+
+			/*
+			 * We only reprogram the broadcast timer if we
+			 * did not mark ourself in the force mask and
+			 * if the cpu local event is earlier than the
+			 * broadcast event. If the current CPU is in
+			 * the force mask, then we are going to be
+			 * woken by the IPI right away; we return
+			 * busy, so the CPU does not try to go deep
+			 * idle.
+			 */
+			if (cpumask_test_cpu(cpu, tick_broadcast_force_mask)) {
+				ret = -EBUSY;
+			} else if (dev->next_event < bc->next_event) {
+				tick_broadcast_set_event(bc, cpu, dev->next_event);
+				/*
+				 * In case of hrtimer broadcasts the
+				 * programming might have moved the
+				 * timer to this cpu. If yes, remove
+				 * us from the broadcast mask and
+				 * return busy.
+				 */
+				ret = broadcast_needs_cpu(bc, cpu);
+				if (ret) {
+					cpumask_clear_cpu(cpu,
+						tick_broadcast_oneshot_mask);
+				}
+			}
+		}
+	} else {
+		if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) {
+			clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
+			/*
+			 * The cpu which was handling the broadcast
+			 * timer marked this cpu in the broadcast
+			 * pending mask and fired the broadcast
+			 * IPI. So we are going to handle the expired
+			 * event anyway via the broadcast IPI
+			 * handler. No need to reprogram the timer
+			 * with an already expired event.
+			 */
+			if (cpumask_test_and_clear_cpu(cpu,
+				       tick_broadcast_pending_mask))
+				goto out;
+
+			/*
+			 * Bail out if there is no next event.
+			 */
+			if (dev->next_event == KTIME_MAX)
+				goto out;
+			/*
+			 * If the pending bit is not set, then we are
+			 * either the CPU handling the broadcast
+			 * interrupt or we got woken by something else.
+			 *
+			 * We are no longer in the broadcast mask, so
+			 * if the cpu local expiry time is already
+			 * reached, we would reprogram the cpu local
+			 * timer with an already expired event.
+			 *
+			 * This can lead to a ping-pong when we return
+			 * to idle and therefore rearm the broadcast
+			 * timer before the cpu local timer was able
+			 * to fire. This happens because the forced
+			 * reprogramming makes sure that the event
+			 * will happen in the future and depending on
+			 * the min_delta setting this might be far
+			 * enough out that the ping-pong starts.
+			 *
+			 * If the cpu local next_event has expired
+			 * then we know that the broadcast timer
+			 * next_event has expired as well and
+			 * broadcast is about to be handled. So we
+			 * avoid reprogramming and enforce that the
+			 * broadcast handler, which did not run yet,
+			 * will invoke the cpu local handler.
+			 *
+			 * We cannot call the handler directly from
+			 * here, because we might be in a NOHZ phase
+			 * and we did not go through the irq_enter()
+			 * nohz fixups.
+			 */
+			now = ktime_get();
+			if (dev->next_event <= now) {
+				cpumask_set_cpu(cpu, tick_broadcast_force_mask);
+				goto out;
+			}
+			/*
+			 * We got woken by something else. Reprogram
+			 * the cpu local timer device.
+			 */
+			tick_program_event(dev->next_event, 1);
+		}
+	}
+out:
+	raw_spin_unlock(&tick_broadcast_lock);
+	return ret;
+}
+
+/*
+ * Reset the one shot broadcast for a cpu
+ *
+ * Called with tick_broadcast_lock held
+ */
+static void tick_broadcast_clear_oneshot(int cpu)
+{
+	cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
+	cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
+}
+
+static void tick_broadcast_init_next_event(struct cpumask *mask,
+					   ktime_t expires)
+{
+	struct tick_device *td;
+	int cpu;
+
+	for_each_cpu(cpu, mask) {
+		td = &per_cpu(tick_cpu_device, cpu);
+		if (td->evtdev)
+			td->evtdev->next_event = expires;
+	}
+}
+
+/**
+ * tick_broadcast_setup_oneshot - setup the broadcast device
+ */
+static void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
+{
+	int cpu = smp_processor_id();
+
+	if (!bc)
+		return;
+
+	/* Set it up only once ! */
+	if (bc->event_handler != tick_handle_oneshot_broadcast) {
+		int was_periodic = clockevent_state_periodic(bc);
+
+		bc->event_handler = tick_handle_oneshot_broadcast;
+
+		/*
+		 * We must be careful here. There might be other CPUs
+		 * waiting for periodic broadcast. We need to set the
+		 * oneshot_mask bits for those and program the
+		 * broadcast device to fire.
+		 */
+		cpumask_copy(tmpmask, tick_broadcast_mask);
+		cpumask_clear_cpu(cpu, tmpmask);
+		cpumask_or(tick_broadcast_oneshot_mask,
+			   tick_broadcast_oneshot_mask, tmpmask);
+
+		if (was_periodic && !cpumask_empty(tmpmask)) {
+			clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
+			tick_broadcast_init_next_event(tmpmask,
+						       tick_next_period);
+			tick_broadcast_set_event(bc, cpu, tick_next_period);
+		} else
+			bc->next_event = KTIME_MAX;
+	} else {
+		/*
+		 * The first cpu which switches to oneshot mode sets
+		 * the bit for all other cpus which are in the general
+		 * (periodic) broadcast mask. So the bit is set and
+		 * would prevent the first broadcast enter after this
+		 * to program the bc device.
+		 */
+		tick_broadcast_clear_oneshot(cpu);
+	}
+}
+
+/*
+ * Select oneshot operating mode for the broadcast device
+ */
+void tick_broadcast_switch_to_oneshot(void)
+{
+	struct clock_event_device *bc;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
+	bc = tick_broadcast_device.evtdev;
+	if (bc)
+		tick_broadcast_setup_oneshot(bc);
+
+	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+void hotplug_cpu__broadcast_tick_pull(int deadcpu)
+{
+	struct clock_event_device *bc;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
+	bc = tick_broadcast_device.evtdev;
+
+	if (bc && broadcast_needs_cpu(bc, deadcpu)) {
+		/* This moves the broadcast assignment to this CPU: */
+		clockevents_program_event(bc, bc->next_event, 1);
+	}
+	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+/*
+ * Remove a dying CPU from broadcasting
+ */
+static void tick_broadcast_oneshot_offline(unsigned int cpu)
+{
+	/*
+	 * Clear the broadcast masks for the dead cpu, but do not stop
+	 * the broadcast device!
+	 */
+	cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
+	cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
+	cpumask_clear_cpu(cpu, tick_broadcast_force_mask);
+}
+#endif
+
+/*
+ * Check, whether the broadcast device is in one shot mode
+ */
+int tick_broadcast_oneshot_active(void)
+{
+	return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
+}
+
+/*
+ * Check whether the broadcast device supports oneshot.
+ */
+bool tick_broadcast_oneshot_available(void)
+{
+	struct clock_event_device *bc = tick_broadcast_device.evtdev;
+
+	return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
+}
+
+#else
+int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
+{
+	struct clock_event_device *bc = tick_broadcast_device.evtdev;
+
+	if (!bc || (bc->features & CLOCK_EVT_FEAT_HRTIMER))
+		return -EBUSY;
+
+	return 0;
+}
+#endif
+
+void __init tick_broadcast_init(void)
+{
+	zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT);
+	zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT);
+	zalloc_cpumask_var(&tmpmask, GFP_NOWAIT);
+#ifdef CONFIG_TICK_ONESHOT
+	zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT);
+	zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT);
+	zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT);
+#endif
+}