Message-ID: <20220919101521.206622076@infradead.org>
Date:   Mon, 19 Sep 2022 11:59:52 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     peterz@...radead.org
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Subject: [PATCH v2 13/44] cpuidle: Fix ct_idle_*() usage

The whole disable-RCU, enable-IRQS dance is very intricate since
changing IRQ state is traced, which depends on RCU.

Add two helpers for the cpuidle case that mirror the entry code.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/arm/mach-imx/cpuidle-imx6q.c    |    4 +--
 arch/arm/mach-imx/cpuidle-imx6sx.c   |    4 +--
 arch/arm/mach-omap2/cpuidle34xx.c    |    4 +--
 arch/arm/mach-omap2/cpuidle44xx.c    |    8 +++---
 drivers/acpi/processor_idle.c        |    8 ++++--
 drivers/cpuidle/cpuidle-big_little.c |    4 +--
 drivers/cpuidle/cpuidle-mvebu-v7.c   |    4 +--
 drivers/cpuidle/cpuidle-psci.c       |    4 +--
 drivers/cpuidle/cpuidle-riscv-sbi.c  |    4 +--
 drivers/cpuidle/cpuidle-tegra.c      |    8 +++---
 drivers/cpuidle/cpuidle.c            |   11 ++++----
 include/linux/cpuidle.h              |   38 ++++++++++++++++++++++++++---
 kernel/sched/idle.c                  |   45 ++++++++++-------------------------
 kernel/time/tick-broadcast.c         |    6 +++-
 14 files changed, 86 insertions(+), 66 deletions(-)

--- a/arch/arm/mach-imx/cpuidle-imx6q.c
+++ b/arch/arm/mach-imx/cpuidle-imx6q.c
@@ -25,9 +25,9 @@ static int imx6q_enter_wait(struct cpuid
 		imx6_set_lpm(WAIT_UNCLOCKED);
 	raw_spin_unlock(&cpuidle_lock);
 
-	ct_idle_enter();
+	ct_cpuidle_enter();
 	cpu_do_idle();
-	ct_idle_exit();
+	ct_cpuidle_exit();
 
 	raw_spin_lock(&cpuidle_lock);
 	if (num_idle_cpus-- == num_online_cpus())
--- a/arch/arm/mach-imx/cpuidle-imx6sx.c
+++ b/arch/arm/mach-imx/cpuidle-imx6sx.c
@@ -47,9 +47,9 @@ static int imx6sx_enter_wait(struct cpui
 		cpu_pm_enter();
 		cpu_cluster_pm_enter();
 
-		ct_idle_enter();
+		ct_cpuidle_enter();
 		cpu_suspend(0, imx6sx_idle_finish);
-		ct_idle_exit();
+		ct_cpuidle_exit();
 
 		cpu_cluster_pm_exit();
 		cpu_pm_exit();
--- a/arch/arm/mach-omap2/cpuidle34xx.c
+++ b/arch/arm/mach-omap2/cpuidle34xx.c
@@ -133,9 +133,9 @@ static int omap3_enter_idle(struct cpuid
 	}
 
 	/* Execute ARM wfi */
-	ct_idle_enter();
+	ct_cpuidle_enter();
 	omap_sram_idle();
-	ct_idle_exit();
+	ct_cpuidle_exit();
 
 	/*
 	 * Call idle CPU PM enter notifier chain to restore
--- a/arch/arm/mach-omap2/cpuidle44xx.c
+++ b/arch/arm/mach-omap2/cpuidle44xx.c
@@ -105,9 +105,9 @@ static int omap_enter_idle_smp(struct cp
 	}
 	raw_spin_unlock_irqrestore(&mpu_lock, flag);
 
-	ct_idle_enter();
+	ct_cpuidle_enter();
 	omap4_enter_lowpower(dev->cpu, cx->cpu_state);
-	ct_idle_exit();
+	ct_cpuidle_exit();
 
 	raw_spin_lock_irqsave(&mpu_lock, flag);
 	if (cx->mpu_state_vote == num_online_cpus())
@@ -186,10 +186,10 @@ static int omap_enter_idle_coupled(struc
 		}
 	}
 
-	ct_idle_enter();
+	ct_cpuidle_enter();
 	omap4_enter_lowpower(dev->cpu, cx->cpu_state);
 	cpu_done[dev->cpu] = true;
-	ct_idle_exit();
+	ct_cpuidle_exit();
 
 	/* Wakeup CPU1 only if it is not offlined */
 	if (dev->cpu == 0 && cpumask_test_cpu(1, cpu_online_mask)) {
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -627,6 +627,8 @@ static int __cpuidle acpi_idle_enter_bm(
 	 */
 	bool dis_bm = pr->flags.bm_control;
 
+	instrumentation_begin();
+
 	/* If we can skip BM, demote to a safe state. */
 	if (!cx->bm_sts_skip && acpi_idle_bm_check()) {
 		dis_bm = false;
@@ -648,11 +650,11 @@ static int __cpuidle acpi_idle_enter_bm(
 		raw_spin_unlock(&c3_lock);
 	}
 
-	ct_idle_enter();
+	ct_cpuidle_enter();
 
 	acpi_idle_do_entry(cx);
 
-	ct_idle_exit();
+	ct_cpuidle_exit();
 
 	/* Re-enable bus master arbitration */
 	if (dis_bm) {
@@ -662,6 +664,8 @@ static int __cpuidle acpi_idle_enter_bm(
 		raw_spin_unlock(&c3_lock);
 	}
 
+	instrumentation_end();
+
 	return index;
 }
 
--- a/drivers/cpuidle/cpuidle-big_little.c
+++ b/drivers/cpuidle/cpuidle-big_little.c
@@ -126,13 +126,13 @@ static int bl_enter_powerdown(struct cpu
 				struct cpuidle_driver *drv, int idx)
 {
 	cpu_pm_enter();
-	ct_idle_enter();
+	ct_cpuidle_enter();
 
 	cpu_suspend(0, bl_powerdown_finisher);
 
 	/* signals the MCPM core that CPU is out of low power state */
 	mcpm_cpu_powered_up();
-	ct_idle_exit();
+	ct_cpuidle_exit();
 
 	cpu_pm_exit();
 
--- a/drivers/cpuidle/cpuidle-mvebu-v7.c
+++ b/drivers/cpuidle/cpuidle-mvebu-v7.c
@@ -36,9 +36,9 @@ static int mvebu_v7_enter_idle(struct cp
 	if (drv->states[index].flags & MVEBU_V7_FLAG_DEEP_IDLE)
 		deepidle = true;
 
-	ct_idle_enter();
+	ct_cpuidle_enter();
 	ret = mvebu_v7_cpu_suspend(deepidle);
-	ct_idle_exit();
+	ct_cpuidle_exit();
 
 	cpu_pm_exit();
 
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -74,7 +74,7 @@ static int __psci_enter_domain_idle_stat
 	else
 		pm_runtime_put_sync_suspend(pd_dev);
 
-	ct_idle_enter();
+	ct_cpuidle_enter();
 
 	state = psci_get_domain_state();
 	if (!state)
@@ -82,7 +82,7 @@ static int __psci_enter_domain_idle_stat
 
 	ret = psci_cpu_suspend_enter(state) ? -1 : idx;
 
-	ct_idle_exit();
+	ct_cpuidle_exit();
 
 	if (s2idle)
 		dev_pm_genpd_resume(pd_dev);
--- a/drivers/cpuidle/cpuidle-riscv-sbi.c
+++ b/drivers/cpuidle/cpuidle-riscv-sbi.c
@@ -121,7 +121,7 @@ static int __sbi_enter_domain_idle_state
 	else
 		pm_runtime_put_sync_suspend(pd_dev);
 
-	ct_idle_enter();
+	ct_cpuidle_enter();
 
 	if (sbi_is_domain_state_available())
 		state = sbi_get_domain_state();
@@ -130,7 +130,7 @@ static int __sbi_enter_domain_idle_state
 
 	ret = sbi_suspend(state) ? -1 : idx;
 
-	ct_idle_exit();
+	ct_cpuidle_exit();
 
 	if (s2idle)
 		dev_pm_genpd_resume(pd_dev);
--- a/drivers/cpuidle/cpuidle-tegra.c
+++ b/drivers/cpuidle/cpuidle-tegra.c
@@ -183,7 +183,7 @@ static int tegra_cpuidle_state_enter(str
 	tegra_pm_set_cpu_in_lp2();
 	cpu_pm_enter();
 
-	ct_idle_enter();
+	ct_cpuidle_enter();
 
 	switch (index) {
 	case TEGRA_C7:
@@ -199,7 +199,7 @@ static int tegra_cpuidle_state_enter(str
 		break;
 	}
 
-	ct_idle_exit();
+	ct_cpuidle_exit();
 
 	cpu_pm_exit();
 	tegra_pm_clear_cpu_in_lp2();
@@ -240,10 +240,10 @@ static int tegra_cpuidle_enter(struct cp
 
 	if (index == TEGRA_C1) {
 		if (do_rcu)
-			ct_idle_enter();
+			ct_cpuidle_enter();
 		ret = arm_cpuidle_simple_enter(dev, drv, index);
 		if (do_rcu)
-			ct_idle_exit();
+			ct_cpuidle_exit();
 	} else
 		ret = tegra_cpuidle_state_enter(dev, index, cpu);
 
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -14,6 +14,7 @@
 #include <linux/mutex.h>
 #include <linux/sched.h>
 #include <linux/sched/clock.h>
+#include <linux/sched/idle.h>
 #include <linux/notifier.h>
 #include <linux/pm_qos.h>
 #include <linux/cpu.h>
@@ -152,12 +153,12 @@ static void enter_s2idle_proper(struct c
 	 */
 	stop_critical_timings();
 	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
-		ct_idle_enter();
+		ct_cpuidle_enter();
 	target_state->enter_s2idle(dev, drv, index);
 	if (WARN_ON_ONCE(!irqs_disabled()))
-		local_irq_disable();
+		raw_local_irq_disable();
 	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
-		ct_idle_exit();
+		ct_cpuidle_exit();
 	tick_unfreeze();
 	start_critical_timings();
 
@@ -235,14 +236,14 @@ int cpuidle_enter_state(struct cpuidle_d
 
 	stop_critical_timings();
 	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
-		ct_idle_enter();
+		ct_cpuidle_enter();
 
 	entered_state = target_state->enter(dev, drv, index);
 	if (WARN_ONCE(!irqs_disabled(), "%ps leaked IRQ state", target_state->enter))
 		raw_local_irq_disable();
 
 	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
-		ct_idle_exit();
+		ct_cpuidle_exit();
 	start_critical_timings();
 
 	sched_clock_idle_wakeup_event();
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -14,6 +14,7 @@
 #include <linux/percpu.h>
 #include <linux/list.h>
 #include <linux/hrtimer.h>
+#include <linux/context_tracking.h>
 
 #define CPUIDLE_STATE_MAX	10
 #define CPUIDLE_NAME_LEN	16
@@ -115,6 +116,35 @@ struct cpuidle_device {
 DECLARE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
 DECLARE_PER_CPU(struct cpuidle_device, cpuidle_dev);
 
+static __always_inline void ct_cpuidle_enter(void)
+{
+	lockdep_assert_irqs_disabled();
+	/*
+	 * Idle is allowed to (temporary) enable IRQs. It
+	 * will return with IRQs disabled.
+	 *
+	 * Trace IRQs enable here, then switch off RCU, and have
+	 * arch_cpu_idle() use raw_local_irq_enable(). Note that
+	 * ct_idle_enter() relies on lockdep IRQ state, so switch that
+	 * last -- this is very similar to the entry code.
+	 */
+	trace_hardirqs_on_prepare();
+	lockdep_hardirqs_on_prepare();
+	instrumentation_end();
+	ct_idle_enter();
+	lockdep_hardirqs_on(_THIS_IP_);
+}
+
+static __always_inline void ct_cpuidle_exit(void)
+{
+	/*
+	 * Carefully undo the above.
+	 */
+	lockdep_hardirqs_off(_THIS_IP_);
+	ct_idle_exit();
+	instrumentation_begin();
+}
+
 /****************************
  * CPUIDLE DRIVER INTERFACE *
  ****************************/
@@ -282,18 +312,18 @@ extern s64 cpuidle_governor_latency_req(
 	int __ret = 0;							\
 									\
 	if (!idx) {							\
-		ct_idle_enter();					\
+		ct_cpuidle_enter();					\
 		cpu_do_idle();						\
-		ct_idle_exit();						\
+		ct_cpuidle_exit();					\
 		return idx;						\
 	}								\
 									\
 	if (!is_retention)						\
 		__ret =  cpu_pm_enter();				\
 	if (!__ret) {							\
-		ct_idle_enter();					\
+		ct_cpuidle_enter();					\
 		__ret = low_level_idle_enter(state);			\
-		ct_idle_exit();						\
+		ct_cpuidle_exit();					\
 		if (!is_retention)					\
 			cpu_pm_exit();					\
 	}								\
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -51,18 +51,22 @@ __setup("hlt", cpu_idle_nopoll_setup);
 
 static noinline int __cpuidle cpu_idle_poll(void)
 {
+	instrumentation_begin();
 	trace_cpu_idle(0, smp_processor_id());
 	stop_critical_timings();
-	ct_idle_enter();
-	local_irq_enable();
+	ct_cpuidle_enter();
 
+	raw_local_irq_enable();
 	while (!tif_need_resched() &&
 	       (cpu_idle_force_poll || tick_check_broadcast_expired()))
 		cpu_relax();
+	raw_local_irq_disable();
 
-	ct_idle_exit();
+	ct_cpuidle_exit();
 	start_critical_timings();
 	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
+	local_irq_enable();
+	instrumentation_end();
 
 	return 1;
 }
@@ -85,44 +89,21 @@ void __weak arch_cpu_idle(void)
  */
 void __cpuidle default_idle_call(void)
 {
-	if (current_clr_polling_and_test()) {
-		local_irq_enable();
-	} else {
-
+	instrumentation_begin();
+	if (!current_clr_polling_and_test()) {
 		trace_cpu_idle(1, smp_processor_id());
 		stop_critical_timings();
 
-		/*
-		 * arch_cpu_idle() is supposed to enable IRQs, however
-		 * we can't do that because of RCU and tracing.
-		 *
-		 * Trace IRQs enable here, then switch off RCU, and have
-		 * arch_cpu_idle() use raw_local_irq_enable(). Note that
-		 * ct_idle_enter() relies on lockdep IRQ state, so switch that
-		 * last -- this is very similar to the entry code.
-		 */
-		trace_hardirqs_on_prepare();
-		lockdep_hardirqs_on_prepare();
-		ct_idle_enter();
-		lockdep_hardirqs_on(_THIS_IP_);
-
+		ct_cpuidle_enter();
 		arch_cpu_idle();
-
-		/*
-		 * OK, so IRQs are enabled here, but RCU needs them disabled to
-		 * turn itself back on.. funny thing is that disabling IRQs
-		 * will cause tracing, which needs RCU. Jump through hoops to
-		 * make it 'work'.
-		 */
 		raw_local_irq_disable();
-		lockdep_hardirqs_off(_THIS_IP_);
-		ct_idle_exit();
-		lockdep_hardirqs_on(_THIS_IP_);
-		raw_local_irq_enable();
+		ct_cpuidle_exit();
 
 		start_critical_timings();
 		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 	}
+	local_irq_enable();
+	instrumentation_end();
 }
 
 static int call_cpuidle_s2idle(struct cpuidle_driver *drv,
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -622,9 +622,13 @@ struct cpumask *tick_get_broadcast_onesh
  * to avoid a deep idle transition as we are about to get the
  * broadcast IPI right away.
  */
-int tick_check_broadcast_expired(void)
+noinstr int tick_check_broadcast_expired(void)
 {
+#ifdef _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H
+	return arch_test_bit(smp_processor_id(), cpumask_bits(tick_broadcast_force_mask));
+#else
 	return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask);
+#endif
 }
 
 /*

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