1 files changed, 265 insertions, 0 deletions

diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
new file mode 100644
index 000000000000..8f4390a079c7
--- /dev/null
+++ b/kernel/sched/idle.c
@@ -0,0 +1,265 @@
+/*
+ * 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>
+
+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
+ * return non-zero on failure
+ */
+static int 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, ret;
+        bool broadcast;
+
+        /*
+         * Check if the idle task must be rescheduled. If it is the
+         * case, exit the function after re-enabling the local irq and
+         * set again the polling flag
+         */
+        if (current_clr_polling_and_test()) {
+                local_irq_enable();
+                __current_set_polling();
+                return 0;
+        }
+
+        /*
+         * 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();
+
+        /*
+         * Check if the cpuidle framework is ready, otherwise fallback
+         * to the default arch specific idle method
+         */
+        ret = cpuidle_enabled(drv, dev);
+
+        if (!ret) {
+                /*
+                 * Ask the governor to choose an idle state it thinks
+                 * it is convenient to go to. There is *always* a
+                 * convenient idle state
+                 */
+                next_state = cpuidle_select(drv, dev);
+
+                /*
+                 * 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();
+                } else {
+                        broadcast = !!(drv->states[next_state].flags &
+                                       CPUIDLE_FLAG_TIMER_STOP);
+
+                        if (broadcast)
+                                /*
+                                 * 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
+                                 */
+                                ret = clockevents_notify(
+                                        CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
+                                        &dev->cpu);
+
+                        if (!ret) {
+                                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);
+                        }
+                }
+        }
+
+        /*
+         * We can't use the cpuidle framework, let's use the default
+         * idle routine
+         */
+        if (ret)
+                arch_cpu_idle();
+
+        __current_set_polling();
+
+        /*
+         * It is up to the idle functions to enable back the local
+         * interrupt
+         */
+        if (WARN_ON_ONCE(irqs_disabled()))
+                local_irq_enable();
+
+        rcu_idle_exit();
+        start_critical_timings();
+
+        return 0;
+}
+
+/*
+ * Generic idle loop implementation
+ */
+static void cpu_idle_loop(void)
+{
+        while (1) {
+                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();
+                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
+        __current_set_polling();
+        arch_cpu_idle_prepare();
+        cpu_idle_loop();
+}