sched/idle: Move cpu/idle.c to sched/idle.c

Integration of cpuidle with the scheduler requires that the idle loop be
closely integrated with the scheduler proper. Moving cpu/idle.c into the
sched directory will allow for a smoother integration, and eliminate a
subdirectory which contained only one source file.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/alpine.LFD.2.11.1401301102210.1652@knanqh.ubzr
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 175 insertions, 0 deletions

diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile
index deaf90e4a..078c9feb3 100644
--- a/kernel/sched/Makefile
+++ b/kernel/sched/Makefile
@@ -12,6 +12,7 @@ CFLAGS_core.o := $(PROFILING) -fno-omit-frame-pointer
 endif
 
 obj-y += core.o clock.o cputime.o idle_task.o fair.o rt.o stop_task.o
+obj-y += idle.o
 obj-$(CONFIG_SMP) += cpupri.o
 obj-$(CONFIG_SCHED_AUTOGROUP) += auto_group.o
 obj-$(CONFIG_SCHEDSTATS) += stats.o
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
new file mode 100644
index 000000000..c378dc659
--- /dev/null
+++ b/kernel/sched/idle.c
@@ -0,0 +1,174 @@
+/*
+ * Generic entry point for the idle threads
+ */
+#include <linux/sched.h>
+#include <linux/cpu.h>
+#include <linux/tick.h>
+#include <linux/mm.h>
+#ifdef CONFIG_MT_LOAD_BALANCE_PROFILER
+#include <mtlbprof/mtlbprof.h>
+#endif
+#include <linux/stackprotector.h>
+#include <linux/percpu.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);
+	}
+
+	/* Make sure poll mode is entered on all CPUs after the flag is set */
+	mb();
+}
+
+static DEFINE_PER_CPU(int, idle_force_poll);
+
+void per_cpu_idle_poll_ctrl(int cpu, bool enable)
+{
+	if (enable) {
+		per_cpu(idle_force_poll, cpu)++;
+	} else {
+		per_cpu(idle_force_poll, cpu)--;
+		WARN_ON_ONCE(per_cpu(idle_force_poll, cpu) < 0);
+	}
+
+	/*
+	 * Make sure poll mode is entered on the relevant CPU after the flag is
+	 * set
+	 */
+	mb();
+}
+
+#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_idle_force_poll ||
+		__get_cpu_var(idle_force_poll)))
+		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();
+}
+
+/*
+ * Generic idle loop implementation
+ */
+static void cpu_idle_loop(void)
+{
+#ifdef CONFIG_MT_LOAD_BALANCE_PROFILER
+	mt_lbprof_update_state(smp_processor_id(), MT_LBPROF_NO_TASK_STATE);
+#endif
+
+	while (1) {
+		tick_nohz_idle_enter();
+
+		while (!need_resched()) {
+			check_pgt_cache();
+			rmb();
+
+			if (cpu_is_offline(smp_processor_id()))
+				arch_cpu_idle_dead();
+
+#ifdef CONFIG_MT_LOAD_BALANCE_PROFILER
+			mt_lbprof_update_state(smp_processor_id(), MT_LBPROF_IDLE_STATE);
+#endif
+
+			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() ||
+			    __get_cpu_var(idle_force_poll)) {
+				cpu_idle_poll();
+			} else {
+				if (!current_clr_polling_and_test()) {
+					stop_critical_timings();
+					rcu_idle_enter();
+					arch_cpu_idle();
+					WARN_ON_ONCE(irqs_disabled());
+					rcu_idle_exit();
+					start_critical_timings();
+#ifdef CONFIG_MT_LOAD_BALANCE_PROFILER				
+					mt_lbprof_update_state(smp_processor_id(), MT_LBPROF_NO_TASK_STATE);
+#endif				
+				} else {
+					local_irq_enable();
+				}
+				__current_set_polling();
+			}
+			arch_cpu_idle_exit();
+		}
+		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();
+	per_cpu(idle_force_poll, smp_processor_id()) = 0;
+	cpu_idle_loop();
+}