1 files changed, 273 insertions, 0 deletions
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
new file mode 100644
index 00000000000..cf009fb0bc2
--- /dev/null
+++ b/kernel/sched/idle.c
@@ -0,0 +1,273 @@
+/*
+ * Generic entry point for the idle threads
+ */
+#include <linux/sched.h>
+#include <linux/cpu.h>
+#include <linux/cpuidle.h>
+#include <linux/tick.h>
+#include <linux/mm.h>
+#include <linux/stackprotector.h>
+
+#include <asm/tlb.h>
+
+#include <trace/events/power.h>
+
+#include "sched.h"
+
+static int __read_mostly cpu_idle_force_poll;
+
+void cpu_idle_poll_ctrl(bool enable)
+{
+	if (enable) {
+		cpu_idle_force_poll++;
+	} else {
+		cpu_idle_force_poll--;
+		WARN_ON_ONCE(cpu_idle_force_poll < 0);
+	}
+}
+
+#ifdef CONFIG_GENERIC_IDLE_POLL_SETUP
+static int __init cpu_idle_poll_setup(char *__unused)
+{
+	cpu_idle_force_poll = 1;
+	return 1;
+}
+__setup("nohlt", cpu_idle_poll_setup);
+
+static int __init cpu_idle_nopoll_setup(char *__unused)
+{
+	cpu_idle_force_poll = 0;
+	return 1;
+}
+__setup("hlt", cpu_idle_nopoll_setup);
+#endif
+
+static inline int cpu_idle_poll(void)
+{
+	rcu_idle_enter();
+	trace_cpu_idle_rcuidle(0, smp_processor_id());
+	local_irq_enable();
+	while (!tif_need_resched())
+		cpu_relax();
+	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
+	rcu_idle_exit();
+	return 1;
+}
+
+/* Weak implementations for optional arch specific functions */
+void __weak arch_cpu_idle_prepare(void) { }
+void __weak arch_cpu_idle_enter(void) { }
+void __weak arch_cpu_idle_exit(void) { }
+void __weak arch_cpu_idle_dead(void) { }
+void __weak arch_cpu_idle(void)
+{
+	cpu_idle_force_poll = 1;
+	local_irq_enable();
+}
+
+/**
+ * cpuidle_idle_call - the main idle function
+ *
+ * NOTE: no locks or semaphores should be used here
+ *
+ * On archs that support TIF_POLLING_NRFLAG, is called with polling
+ * set, and it returns with polling set.  If it ever stops polling, it
+ * must clear the polling bit.
+ */
+static void cpuidle_idle_call(void)
+{
+	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
+	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
+	int next_state, entered_state;
+	bool broadcast;
+
+	/*
+	 * Check if the idle task must be rescheduled. If it is the
+	 * case, exit the function after re-enabling the local irq.
+	 */
+	if (need_resched()) {
+		local_irq_enable();
+		return;
+	}
+
+	/*
+	 * During the idle period, stop measuring the disabled irqs
+	 * critical sections latencies
+	 */
+	stop_critical_timings();
+
+	/*
+	 * Tell the RCU framework we are entering an idle section,
+	 * so no more rcu read side critical sections and one more
+	 * step to the grace period
+	 */
+	rcu_idle_enter();
+
+	/*
+	 * Ask the cpuidle framework to choose a convenient idle state.
+	 * Fall back to the default arch idle method on errors.
+	 */
+	next_state = cpuidle_select(drv, dev);
+	if (next_state < 0) {
+use_default:
+		/*
+		 * We can't use the cpuidle framework, let's use the default
+		 * idle routine.
+		 */
+		if (current_clr_polling_and_test())
+			local_irq_enable();
+		else
+			arch_cpu_idle();
+
+		goto exit_idle;
+	}
+
+
+	/*
+	 * The idle task must be scheduled, it is pointless to
+	 * go to idle, just update no idle residency and get
+	 * out of this function
+	 */
+	if (current_clr_polling_and_test()) {
+		dev->last_residency = 0;
+		entered_state = next_state;
+		local_irq_enable();
+		goto exit_idle;
+	}
+
+	broadcast = !!(drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP);
+
+	/*
+	 * Tell the time framework to switch to a broadcast timer
+	 * because our local timer will be shutdown. If a local timer
+	 * is used from another cpu as a broadcast timer, this call may
+	 * fail if it is not available
+	 */
+	if (broadcast &&
+	    clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu))
+		goto use_default;
+
+	trace_cpu_idle_rcuidle(next_state, dev->cpu);
+
+	/*
+	 * Enter the idle state previously returned by the governor decision.
+	 * This function will block until an interrupt occurs and will take
+	 * care of re-enabling the local interrupts
+	 */
+	entered_state = cpuidle_enter(drv, dev, next_state);
+
+	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
+
+	if (broadcast)
+		clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
+
+	/*
+	 * Give the governor an opportunity to reflect on the outcome
+	 */
+	cpuidle_reflect(dev, entered_state);
+
+exit_idle:
+	__current_set_polling();
+
+	/*
+	 * It is up to the idle functions to reenable local interrupts
+	 */
+	if (WARN_ON_ONCE(irqs_disabled()))
+		local_irq_enable();
+
+	rcu_idle_exit();
+	start_critical_timings();
+}
+
+/*
+ * Generic idle loop implementation
+ *
+ * Called with polling cleared.
+ */
+static void cpu_idle_loop(void)
+{
+	while (1) {
+		/*
+		 * If the arch has a polling bit, we maintain an invariant:
+		 *
+		 * Our polling bit is clear if we're not scheduled (i.e. if
+		 * rq->curr != rq->idle).  This means that, if rq->idle has
+		 * the polling bit set, then setting need_resched is
+		 * guaranteed to cause the cpu to reschedule.
+		 */
+
+		__current_set_polling();
+		tick_nohz_idle_enter();
+
+		while (!need_resched()) {
+			check_pgt_cache();
+			rmb();
+
+			if (cpu_is_offline(smp_processor_id()))
+				arch_cpu_idle_dead();
+
+			local_irq_disable();
+			arch_cpu_idle_enter();
+
+			/*
+			 * In poll mode we reenable interrupts and spin.
+			 *
+			 * Also if we detected in the wakeup from idle
+			 * path that the tick broadcast device expired
+			 * for us, we don't want to go deep idle as we
+			 * know that the IPI is going to arrive right
+			 * away
+			 */
+			if (cpu_idle_force_poll || tick_check_broadcast_expired())
+				cpu_idle_poll();
+			else
+				cpuidle_idle_call();
+
+			arch_cpu_idle_exit();
+		}
+
+		/*
+		 * Since we fell out of the loop above, we know
+		 * TIF_NEED_RESCHED must be set, propagate it into
+		 * PREEMPT_NEED_RESCHED.
+		 *
+		 * This is required because for polling idle loops we will
+		 * not have had an IPI to fold the state for us.
+		 */
+		preempt_set_need_resched();
+		tick_nohz_idle_exit();
+		__current_clr_polling();
+
+		/*
+		 * We promise to call sched_ttwu_pending and reschedule
+		 * if need_resched is set while polling is set.  That
+		 * means that clearing polling needs to be visible
+		 * before doing these things.
+		 */
+		smp_mb__after_atomic();
+
+		sched_ttwu_pending();
+		schedule_preempt_disabled();
+	}
+}
+
+void cpu_startup_entry(enum cpuhp_state state)
+{
+	/*
+	 * This #ifdef needs to die, but it's too late in the cycle to
+	 * make this generic (arm and sh have never invoked the canary
+	 * init for the non boot cpus!). Will be fixed in 3.11
+	 */
+#ifdef CONFIG_X86
+	/*
+	 * If we're the non-boot CPU, nothing set the stack canary up
+	 * for us. The boot CPU already has it initialized but no harm
+	 * in doing it again. This is a good place for updating it, as
+	 * we wont ever return from this function (so the invalid
+	 * canaries already on the stack wont ever trigger).
+	 */
+	boot_init_stack_canary();
+#endif
+	arch_cpu_idle_prepare();
+	cpu_idle_loop();
+}