From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- kernel/time/tick-common.c | 578 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 578 insertions(+) create mode 100644 kernel/time/tick-common.c (limited to 'kernel/time/tick-common.c') diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c new file mode 100644 index 000000000..e9138cd7a --- /dev/null +++ b/kernel/time/tick-common.c @@ -0,0 +1,578 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This file contains the base functions to manage periodic tick + * related events. + * + * Copyright(C) 2005-2006, Thomas Gleixner + * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar + * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "tick-internal.h" + +/* + * Tick devices + */ +DEFINE_PER_CPU(struct tick_device, tick_cpu_device); +/* + * Tick next event: keeps track of the tick time. It's updated by the + * CPU which handles the tick and protected by jiffies_lock. There is + * no requirement to write hold the jiffies seqcount for it. + */ +ktime_t tick_next_period; + +/* + * tick_do_timer_cpu is a timer core internal variable which holds the CPU NR + * which is responsible for calling do_timer(), i.e. the timekeeping stuff. This + * variable has two functions: + * + * 1) Prevent a thundering herd issue of a gazillion of CPUs trying to grab the + * timekeeping lock all at once. Only the CPU which is assigned to do the + * update is handling it. + * + * 2) Hand off the duty in the NOHZ idle case by setting the value to + * TICK_DO_TIMER_NONE, i.e. a non existing CPU. So the next cpu which looks + * at it will take over and keep the time keeping alive. The handover + * procedure also covers cpu hotplug. + */ +int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT; +#ifdef CONFIG_NO_HZ_FULL +/* + * tick_do_timer_boot_cpu indicates the boot CPU temporarily owns + * tick_do_timer_cpu and it should be taken over by an eligible secondary + * when one comes online. + */ +static int tick_do_timer_boot_cpu __read_mostly = -1; +#endif + +/* + * Debugging: see timer_list.c + */ +struct tick_device *tick_get_device(int cpu) +{ + return &per_cpu(tick_cpu_device, cpu); +} + +/** + * tick_is_oneshot_available - check for a oneshot capable event device + */ +int tick_is_oneshot_available(void) +{ + struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); + + if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT)) + return 0; + if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) + return 1; + return tick_broadcast_oneshot_available(); +} + +/* + * Periodic tick + */ +static void tick_periodic(int cpu) +{ + if (tick_do_timer_cpu == cpu) { + raw_spin_lock(&jiffies_lock); + write_seqcount_begin(&jiffies_seq); + + /* Keep track of the next tick event */ + tick_next_period = ktime_add_ns(tick_next_period, TICK_NSEC); + + do_timer(1); + write_seqcount_end(&jiffies_seq); + raw_spin_unlock(&jiffies_lock); + update_wall_time(); + } + + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); +} + +/* + * Event handler for periodic ticks + */ +void tick_handle_periodic(struct clock_event_device *dev) +{ + int cpu = smp_processor_id(); + ktime_t next = dev->next_event; + + tick_periodic(cpu); + +#if defined(CONFIG_HIGH_RES_TIMERS) || defined(CONFIG_NO_HZ_COMMON) + /* + * The cpu might have transitioned to HIGHRES or NOHZ mode via + * update_process_times() -> run_local_timers() -> + * hrtimer_run_queues(). + */ + if (dev->event_handler != tick_handle_periodic) + return; +#endif + + if (!clockevent_state_oneshot(dev)) + return; + for (;;) { + /* + * Setup the next period for devices, which do not have + * periodic mode: + */ + next = ktime_add_ns(next, TICK_NSEC); + + if (!clockevents_program_event(dev, next, false)) + return; + /* + * Have to be careful here. If we're in oneshot mode, + * before we call tick_periodic() in a loop, we need + * to be sure we're using a real hardware clocksource. + * Otherwise we could get trapped in an infinite + * loop, as the tick_periodic() increments jiffies, + * which then will increment time, possibly causing + * the loop to trigger again and again. + */ + if (timekeeping_valid_for_hres()) + tick_periodic(cpu); + } +} + +/* + * Setup the device for a periodic tick + */ +void tick_setup_periodic(struct clock_event_device *dev, int broadcast) +{ + tick_set_periodic_handler(dev, broadcast); + + /* Broadcast setup ? */ + if (!tick_device_is_functional(dev)) + return; + + if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) && + !tick_broadcast_oneshot_active()) { + clockevents_switch_state(dev, CLOCK_EVT_STATE_PERIODIC); + } else { + unsigned int seq; + ktime_t next; + + do { + seq = read_seqcount_begin(&jiffies_seq); + next = tick_next_period; + } while (read_seqcount_retry(&jiffies_seq, seq)); + + clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT); + + for (;;) { + if (!clockevents_program_event(dev, next, false)) + return; + next = ktime_add_ns(next, TICK_NSEC); + } + } +} + +#ifdef CONFIG_NO_HZ_FULL +static void giveup_do_timer(void *info) +{ + int cpu = *(unsigned int *)info; + + WARN_ON(tick_do_timer_cpu != smp_processor_id()); + + tick_do_timer_cpu = cpu; +} + +static void tick_take_do_timer_from_boot(void) +{ + int cpu = smp_processor_id(); + int from = tick_do_timer_boot_cpu; + + if (from >= 0 && from != cpu) + smp_call_function_single(from, giveup_do_timer, &cpu, 1); +} +#endif + +/* + * Setup the tick device + */ +static void tick_setup_device(struct tick_device *td, + struct clock_event_device *newdev, int cpu, + const struct cpumask *cpumask) +{ + void (*handler)(struct clock_event_device *) = NULL; + ktime_t next_event = 0; + + /* + * First device setup ? + */ + if (!td->evtdev) { + /* + * If no cpu took the do_timer update, assign it to + * this cpu: + */ + if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) { + tick_do_timer_cpu = cpu; + tick_next_period = ktime_get(); +#ifdef CONFIG_NO_HZ_FULL + /* + * The boot CPU may be nohz_full, in which case set + * tick_do_timer_boot_cpu so the first housekeeping + * secondary that comes up will take do_timer from + * us. + */ + if (tick_nohz_full_cpu(cpu)) + tick_do_timer_boot_cpu = cpu; + + } else if (tick_do_timer_boot_cpu != -1 && + !tick_nohz_full_cpu(cpu)) { + tick_take_do_timer_from_boot(); + tick_do_timer_boot_cpu = -1; + WARN_ON(tick_do_timer_cpu != cpu); +#endif + } + + /* + * Startup in periodic mode first. + */ + td->mode = TICKDEV_MODE_PERIODIC; + } else { + handler = td->evtdev->event_handler; + next_event = td->evtdev->next_event; + td->evtdev->event_handler = clockevents_handle_noop; + } + + td->evtdev = newdev; + + /* + * When the device is not per cpu, pin the interrupt to the + * current cpu: + */ + if (!cpumask_equal(newdev->cpumask, cpumask)) + irq_set_affinity(newdev->irq, cpumask); + + /* + * When global broadcasting is active, check if the current + * device is registered as a placeholder for broadcast mode. + * This allows us to handle this x86 misfeature in a generic + * way. This function also returns !=0 when we keep the + * current active broadcast state for this CPU. + */ + if (tick_device_uses_broadcast(newdev, cpu)) + return; + + if (td->mode == TICKDEV_MODE_PERIODIC) + tick_setup_periodic(newdev, 0); + else + tick_setup_oneshot(newdev, handler, next_event); +} + +void tick_install_replacement(struct clock_event_device *newdev) +{ + struct tick_device *td = this_cpu_ptr(&tick_cpu_device); + int cpu = smp_processor_id(); + + clockevents_exchange_device(td->evtdev, newdev); + tick_setup_device(td, newdev, cpu, cpumask_of(cpu)); + if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) + tick_oneshot_notify(); +} + +static bool tick_check_percpu(struct clock_event_device *curdev, + struct clock_event_device *newdev, int cpu) +{ + if (!cpumask_test_cpu(cpu, newdev->cpumask)) + return false; + if (cpumask_equal(newdev->cpumask, cpumask_of(cpu))) + return true; + /* Check if irq affinity can be set */ + if (newdev->irq >= 0 && !irq_can_set_affinity(newdev->irq)) + return false; + /* Prefer an existing cpu local device */ + if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu))) + return false; + return true; +} + +static bool tick_check_preferred(struct clock_event_device *curdev, + struct clock_event_device *newdev) +{ + /* Prefer oneshot capable device */ + if (!(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) { + if (curdev && (curdev->features & CLOCK_EVT_FEAT_ONESHOT)) + return false; + if (tick_oneshot_mode_active()) + return false; + } + + /* + * Use the higher rated one, but prefer a CPU local device with a lower + * rating than a non-CPU local device + */ + return !curdev || + newdev->rating > curdev->rating || + !cpumask_equal(curdev->cpumask, newdev->cpumask); +} + +/* + * Check whether the new device is a better fit than curdev. curdev + * can be NULL ! + */ +bool tick_check_replacement(struct clock_event_device *curdev, + struct clock_event_device *newdev) +{ + if (!tick_check_percpu(curdev, newdev, smp_processor_id())) + return false; + + return tick_check_preferred(curdev, newdev); +} + +/* + * Check, if the new registered device should be used. Called with + * clockevents_lock held and interrupts disabled. + */ +void tick_check_new_device(struct clock_event_device *newdev) +{ + struct clock_event_device *curdev; + struct tick_device *td; + int cpu; + + cpu = smp_processor_id(); + td = &per_cpu(tick_cpu_device, cpu); + curdev = td->evtdev; + + if (!tick_check_replacement(curdev, newdev)) + goto out_bc; + + if (!try_module_get(newdev->owner)) + return; + + /* + * Replace the eventually existing device by the new + * device. If the current device is the broadcast device, do + * not give it back to the clockevents layer ! + */ + if (tick_is_broadcast_device(curdev)) { + clockevents_shutdown(curdev); + curdev = NULL; + } + clockevents_exchange_device(curdev, newdev); + tick_setup_device(td, newdev, cpu, cpumask_of(cpu)); + if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) + tick_oneshot_notify(); + return; + +out_bc: + /* + * Can the new device be used as a broadcast device ? + */ + tick_install_broadcast_device(newdev, cpu); +} + +/** + * tick_broadcast_oneshot_control - Enter/exit broadcast oneshot mode + * @state: The target state (enter/exit) + * + * The system enters/leaves a state, where affected devices might stop + * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups. + * + * Called with interrupts disabled, so clockevents_lock is not + * required here because the local clock event device cannot go away + * under us. + */ +int tick_broadcast_oneshot_control(enum tick_broadcast_state state) +{ + struct tick_device *td = this_cpu_ptr(&tick_cpu_device); + + if (!(td->evtdev->features & CLOCK_EVT_FEAT_C3STOP)) + return 0; + + return __tick_broadcast_oneshot_control(state); +} +EXPORT_SYMBOL_GPL(tick_broadcast_oneshot_control); + +#ifdef CONFIG_HOTPLUG_CPU +/* + * Transfer the do_timer job away from a dying cpu. + * + * Called with interrupts disabled. No locking required. If + * tick_do_timer_cpu is owned by this cpu, nothing can change it. + */ +void tick_handover_do_timer(void) +{ + if (tick_do_timer_cpu == smp_processor_id()) + tick_do_timer_cpu = cpumask_first(cpu_online_mask); +} + +/* + * Shutdown an event device on a given cpu: + * + * This is called on a life CPU, when a CPU is dead. So we cannot + * access the hardware device itself. + * We just set the mode and remove it from the lists. + */ +void tick_shutdown(unsigned int cpu) +{ + struct tick_device *td = &per_cpu(tick_cpu_device, cpu); + struct clock_event_device *dev = td->evtdev; + + td->mode = TICKDEV_MODE_PERIODIC; + if (dev) { + /* + * Prevent that the clock events layer tries to call + * the set mode function! + */ + clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED); + clockevents_exchange_device(dev, NULL); + dev->event_handler = clockevents_handle_noop; + td->evtdev = NULL; + } +} +#endif + +/** + * tick_suspend_local - Suspend the local tick device + * + * Called from the local cpu for freeze with interrupts disabled. + * + * No locks required. Nothing can change the per cpu device. + */ +void tick_suspend_local(void) +{ + struct tick_device *td = this_cpu_ptr(&tick_cpu_device); + + clockevents_shutdown(td->evtdev); +} + +/** + * tick_resume_local - Resume the local tick device + * + * Called from the local CPU for unfreeze or XEN resume magic. + * + * No locks required. Nothing can change the per cpu device. + */ +void tick_resume_local(void) +{ + struct tick_device *td = this_cpu_ptr(&tick_cpu_device); + bool broadcast = tick_resume_check_broadcast(); + + clockevents_tick_resume(td->evtdev); + if (!broadcast) { + if (td->mode == TICKDEV_MODE_PERIODIC) + tick_setup_periodic(td->evtdev, 0); + else + tick_resume_oneshot(); + } + + /* + * Ensure that hrtimers are up to date and the clockevents device + * is reprogrammed correctly when high resolution timers are + * enabled. + */ + hrtimers_resume_local(); +} + +/** + * tick_suspend - Suspend the tick and the broadcast device + * + * Called from syscore_suspend() via timekeeping_suspend with only one + * CPU online and interrupts disabled or from tick_unfreeze() under + * tick_freeze_lock. + * + * No locks required. Nothing can change the per cpu device. + */ +void tick_suspend(void) +{ + tick_suspend_local(); + tick_suspend_broadcast(); +} + +/** + * tick_resume - Resume the tick and the broadcast device + * + * Called from syscore_resume() via timekeeping_resume with only one + * CPU online and interrupts disabled. + * + * No locks required. Nothing can change the per cpu device. + */ +void tick_resume(void) +{ + tick_resume_broadcast(); + tick_resume_local(); +} + +#ifdef CONFIG_SUSPEND +static DEFINE_RAW_SPINLOCK(tick_freeze_lock); +static unsigned int tick_freeze_depth; + +/** + * tick_freeze - Suspend the local tick and (possibly) timekeeping. + * + * Check if this is the last online CPU executing the function and if so, + * suspend timekeeping. Otherwise suspend the local tick. + * + * Call with interrupts disabled. Must be balanced with %tick_unfreeze(). + * Interrupts must not be enabled before the subsequent %tick_unfreeze(). + */ +void tick_freeze(void) +{ + raw_spin_lock(&tick_freeze_lock); + + tick_freeze_depth++; + if (tick_freeze_depth == num_online_cpus()) { + trace_suspend_resume(TPS("timekeeping_freeze"), + smp_processor_id(), true); + system_state = SYSTEM_SUSPEND; + sched_clock_suspend(); + timekeeping_suspend(); + } else { + tick_suspend_local(); + } + + raw_spin_unlock(&tick_freeze_lock); +} + +/** + * tick_unfreeze - Resume the local tick and (possibly) timekeeping. + * + * Check if this is the first CPU executing the function and if so, resume + * timekeeping. Otherwise resume the local tick. + * + * Call with interrupts disabled. Must be balanced with %tick_freeze(). + * Interrupts must not be enabled after the preceding %tick_freeze(). + */ +void tick_unfreeze(void) +{ + raw_spin_lock(&tick_freeze_lock); + + if (tick_freeze_depth == num_online_cpus()) { + timekeeping_resume(); + sched_clock_resume(); + system_state = SYSTEM_RUNNING; + trace_suspend_resume(TPS("timekeeping_freeze"), + smp_processor_id(), false); + } else { + touch_softlockup_watchdog(); + tick_resume_local(); + } + + tick_freeze_depth--; + + raw_spin_unlock(&tick_freeze_lock); +} +#endif /* CONFIG_SUSPEND */ + +/** + * tick_init - initialize the tick control + */ +void __init tick_init(void) +{ + tick_broadcast_init(); + tick_nohz_init(); +} -- cgit v1.2.3