| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Nico Pitre | 2151 | 75.39% | 13 | 46.43% |
| Dave P Martin | 613 | 21.49% | 7 | 25.00% |
| Sebastian Andrzej Siewior | 56 | 1.96% | 1 | 3.57% |
| Lorenzo Pieralisi | 15 | 0.53% | 1 | 3.57% |
| Thomas Gleixner | 9 | 0.32% | 3 | 10.71% |
| Tushar Behera | 5 | 0.18% | 1 | 3.57% |
| Ingo Molnar | 4 | 0.14% | 2 | 7.14% |
| Total | 2853 | 28 |
// SPDX-License-Identifier: GPL-2.0-only /* * arch/arm/common/bL_switcher.c -- big.LITTLE cluster switcher core driver * * Created by: Nicolas Pitre, March 2012 * Copyright: (C) 2012-2013 Linaro Limited */ #include <linux/atomic.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/sched/signal.h> #include <uapi/linux/sched/types.h> #include <linux/interrupt.h> #include <linux/cpu_pm.h> #include <linux/cpu.h> #include <linux/cpumask.h> #include <linux/kthread.h> #include <linux/wait.h> #include <linux/time.h> #include <linux/clockchips.h> #include <linux/hrtimer.h> #include <linux/tick.h> #include <linux/notifier.h> #include <linux/mm.h> #include <linux/mutex.h> #include <linux/smp.h> #include <linux/spinlock.h> #include <linux/string.h> #include <linux/sysfs.h> #include <linux/irqchip/arm-gic.h> #include <linux/moduleparam.h> #include <asm/smp_plat.h> #include <asm/cputype.h> #include <asm/suspend.h> #include <asm/mcpm.h> #include <asm/bL_switcher.h> #define CREATE_TRACE_POINTS #include <trace/events/power_cpu_migrate.h> /* * Use our own MPIDR accessors as the generic ones in asm/cputype.h have * __attribute_const__ and we don't want the compiler to assume any * constness here as the value _does_ change along some code paths. */ static int read_mpidr(void) { unsigned int id; asm volatile ("mrc p15, 0, %0, c0, c0, 5" : "=r" (id)); return id & MPIDR_HWID_BITMASK; } /* * bL switcher core code. */ static void bL_do_switch(void *_arg) { unsigned ib_mpidr, ib_cpu, ib_cluster; long volatile handshake, **handshake_ptr = _arg; pr_debug("%s\n", __func__); ib_mpidr = cpu_logical_map(smp_processor_id()); ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0); ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1); /* Advertise our handshake location */ if (handshake_ptr) { handshake = 0; *handshake_ptr = &handshake; } else handshake = -1; /* * Our state has been saved at this point. Let's release our * inbound CPU. */ mcpm_set_entry_vector(ib_cpu, ib_cluster, cpu_resume); sev(); /* * From this point, we must assume that our counterpart CPU might * have taken over in its parallel world already, as if execution * just returned from cpu_suspend(). It is therefore important to * be very careful not to make any change the other guy is not * expecting. This is why we need stack isolation. * * Fancy under cover tasks could be performed here. For now * we have none. */ /* * Let's wait until our inbound is alive. */ while (!handshake) { wfe(); smp_mb(); } /* Let's put ourself down. */ mcpm_cpu_power_down(); /* should never get here */ BUG(); } /* * Stack isolation. To ensure 'current' remains valid, we just use another * piece of our thread's stack space which should be fairly lightly used. * The selected area starts just above the thread_info structure located * at the very bottom of the stack, aligned to a cache line, and indexed * with the cluster number. */ #define STACK_SIZE 512 extern void call_with_stack(void (*fn)(void *), void *arg, void *sp); static int bL_switchpoint(unsigned long _arg) { unsigned int mpidr = read_mpidr(); unsigned int clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1); void *stack = current_thread_info() + 1; stack = PTR_ALIGN(stack, L1_CACHE_BYTES); stack += clusterid * STACK_SIZE + STACK_SIZE; call_with_stack(bL_do_switch, (void *)_arg, stack); BUG(); } /* * Generic switcher interface */ static unsigned int bL_gic_id[MAX_CPUS_PER_CLUSTER][MAX_NR_CLUSTERS]; static int bL_switcher_cpu_pairing[NR_CPUS]; /* * bL_switch_to - Switch to a specific cluster for the current CPU * @new_cluster_id: the ID of the cluster to switch to. * * This function must be called on the CPU to be switched. * Returns 0 on success, else a negative status code. */ static int bL_switch_to(unsigned int new_cluster_id) { unsigned int mpidr, this_cpu, that_cpu; unsigned int ob_mpidr, ob_cpu, ob_cluster, ib_mpidr, ib_cpu, ib_cluster; struct completion inbound_alive; long volatile *handshake_ptr; int ipi_nr, ret; this_cpu = smp_processor_id(); ob_mpidr = read_mpidr(); ob_cpu = MPIDR_AFFINITY_LEVEL(ob_mpidr, 0); ob_cluster = MPIDR_AFFINITY_LEVEL(ob_mpidr, 1); BUG_ON(cpu_logical_map(this_cpu) != ob_mpidr); if (new_cluster_id == ob_cluster) return 0; that_cpu = bL_switcher_cpu_pairing[this_cpu]; ib_mpidr = cpu_logical_map(that_cpu); ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0); ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1); pr_debug("before switch: CPU %d MPIDR %#x -> %#x\n", this_cpu, ob_mpidr, ib_mpidr); this_cpu = smp_processor_id(); /* Close the gate for our entry vectors */ mcpm_set_entry_vector(ob_cpu, ob_cluster, NULL); mcpm_set_entry_vector(ib_cpu, ib_cluster, NULL); /* Install our "inbound alive" notifier. */ init_completion(&inbound_alive); ipi_nr = register_ipi_completion(&inbound_alive, this_cpu); ipi_nr |= ((1 << 16) << bL_gic_id[ob_cpu][ob_cluster]); mcpm_set_early_poke(ib_cpu, ib_cluster, gic_get_sgir_physaddr(), ipi_nr); /* * Let's wake up the inbound CPU now in case it requires some delay * to come online, but leave it gated in our entry vector code. */ ret = mcpm_cpu_power_up(ib_cpu, ib_cluster); if (ret) { pr_err("%s: mcpm_cpu_power_up() returned %d\n", __func__, ret); return ret; } /* * Raise a SGI on the inbound CPU to make sure it doesn't stall * in a possible WFI, such as in bL_power_down(). */ gic_send_sgi(bL_gic_id[ib_cpu][ib_cluster], 0); /* * Wait for the inbound to come up. This allows for other * tasks to be scheduled in the mean time. */ wait_for_completion(&inbound_alive); mcpm_set_early_poke(ib_cpu, ib_cluster, 0, 0); /* * From this point we are entering the switch critical zone * and can't take any interrupts anymore. */ local_irq_disable(); local_fiq_disable(); trace_cpu_migrate_begin(ktime_get_real_ns(), ob_mpidr); /* redirect GIC's SGIs to our counterpart */ gic_migrate_target(bL_gic_id[ib_cpu][ib_cluster]); tick_suspend_local(); ret = cpu_pm_enter(); /* we can not tolerate errors at this point */ if (ret) panic("%s: cpu_pm_enter() returned %d\n", __func__, ret); /* Swap the physical CPUs in the logical map for this logical CPU. */ cpu_logical_map(this_cpu) = ib_mpidr; cpu_logical_map(that_cpu) = ob_mpidr; /* Let's do the actual CPU switch. */ ret = cpu_suspend((unsigned long)&handshake_ptr, bL_switchpoint); if (ret > 0) panic("%s: cpu_suspend() returned %d\n", __func__, ret); /* We are executing on the inbound CPU at this point */ mpidr = read_mpidr(); pr_debug("after switch: CPU %d MPIDR %#x\n", this_cpu, mpidr); BUG_ON(mpidr != ib_mpidr); mcpm_cpu_powered_up(); ret = cpu_pm_exit(); tick_resume_local(); trace_cpu_migrate_finish(ktime_get_real_ns(), ib_mpidr); local_fiq_enable(); local_irq_enable(); *handshake_ptr = 1; dsb_sev(); if (ret) pr_err("%s exiting with error %d\n", __func__, ret); return ret; } struct bL_thread { spinlock_t lock; struct task_struct *task; wait_queue_head_t wq; int wanted_cluster; struct completion started; bL_switch_completion_handler completer; void *completer_cookie; }; static struct bL_thread bL_threads[NR_CPUS]; static int bL_switcher_thread(void *arg) { struct bL_thread *t = arg; struct sched_param param = { .sched_priority = 1 }; int cluster; bL_switch_completion_handler completer; void *completer_cookie; sched_setscheduler_nocheck(current, SCHED_FIFO, ¶m); complete(&t->started); do { if (signal_pending(current)) flush_signals(current); wait_event_interruptible(t->wq, t->wanted_cluster != -1 || kthread_should_stop()); spin_lock(&t->lock); cluster = t->wanted_cluster; completer = t->completer; completer_cookie = t->completer_cookie; t->wanted_cluster = -1; t->completer = NULL; spin_unlock(&t->lock); if (cluster != -1) { bL_switch_to(cluster); if (completer) completer(completer_cookie); } } while (!kthread_should_stop()); return 0; } static struct task_struct *bL_switcher_thread_create(int cpu, void *arg) { struct task_struct *task; task = kthread_create_on_node(bL_switcher_thread, arg, cpu_to_node(cpu), "kswitcher_%d", cpu); if (!IS_ERR(task)) { kthread_bind(task, cpu); wake_up_process(task); } else pr_err("%s failed for CPU %d\n", __func__, cpu); return task; } /* * bL_switch_request_cb - Switch to a specific cluster for the given CPU, * with completion notification via a callback * * @cpu: the CPU to switch * @new_cluster_id: the ID of the cluster to switch to. * @completer: switch completion callback. if non-NULL, * @completer(@completer_cookie) will be called on completion of * the switch, in non-atomic context. * @completer_cookie: opaque context argument for @completer. * * This function causes a cluster switch on the given CPU by waking up * the appropriate switcher thread. This function may or may not return * before the switch has occurred. * * If a @completer callback function is supplied, it will be called when * the switch is complete. This can be used to determine asynchronously * when the switch is complete, regardless of when bL_switch_request() * returns. When @completer is supplied, no new switch request is permitted * for the affected CPU until after the switch is complete, and @completer * has returned. */ int bL_switch_request_cb(unsigned int cpu, unsigned int new_cluster_id, bL_switch_completion_handler completer, void *completer_cookie) { struct bL_thread *t; if (cpu >= ARRAY_SIZE(bL_threads)) { pr_err("%s: cpu %d out of bounds\n", __func__, cpu); return -EINVAL; } t = &bL_threads[cpu]; if (IS_ERR(t->task)) return PTR_ERR(t->task); if (!t->task) return -ESRCH; spin_lock(&t->lock); if (t->completer) { spin_unlock(&t->lock); return -EBUSY; } t->completer = completer; t->completer_cookie = completer_cookie; t->wanted_cluster = new_cluster_id; spin_unlock(&t->lock); wake_up(&t->wq); return 0; } EXPORT_SYMBOL_GPL(bL_switch_request_cb); /* * Activation and configuration code. */ static DEFINE_MUTEX(bL_switcher_activation_lock); static BLOCKING_NOTIFIER_HEAD(bL_activation_notifier); static unsigned int bL_switcher_active; static unsigned int bL_switcher_cpu_original_cluster[NR_CPUS]; static cpumask_t bL_switcher_removed_logical_cpus; int bL_switcher_register_notifier(struct notifier_block *nb) { return blocking_notifier_chain_register(&bL_activation_notifier, nb); } EXPORT_SYMBOL_GPL(bL_switcher_register_notifier); int bL_switcher_unregister_notifier(struct notifier_block *nb) { return blocking_notifier_chain_unregister(&bL_activation_notifier, nb); } EXPORT_SYMBOL_GPL(bL_switcher_unregister_notifier); static int bL_activation_notify(unsigned long val) { int ret; ret = blocking_notifier_call_chain(&bL_activation_notifier, val, NULL); if (ret & NOTIFY_STOP_MASK) pr_err("%s: notifier chain failed with status 0x%x\n", __func__, ret); return notifier_to_errno(ret); } static void bL_switcher_restore_cpus(void) { int i; for_each_cpu(i, &bL_switcher_removed_logical_cpus) { struct device *cpu_dev = get_cpu_device(i); int ret = device_online(cpu_dev); if (ret) dev_err(cpu_dev, "switcher: unable to restore CPU\n"); } } static int bL_switcher_halve_cpus(void) { int i, j, cluster_0, gic_id, ret; unsigned int cpu, cluster, mask; cpumask_t available_cpus; /* First pass to validate what we have */ mask = 0; for_each_online_cpu(i) { cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0); cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); if (cluster >= 2) { pr_err("%s: only dual cluster systems are supported\n", __func__); return -EINVAL; } if (WARN_ON(cpu >= MAX_CPUS_PER_CLUSTER)) return -EINVAL; mask |= (1 << cluster); } if (mask != 3) { pr_err("%s: no CPU pairing possible\n", __func__); return -EINVAL; } /* * Now let's do the pairing. We match each CPU with another CPU * from a different cluster. To get a uniform scheduling behavior * without fiddling with CPU topology and compute capacity data, * we'll use logical CPUs initially belonging to the same cluster. */ memset(bL_switcher_cpu_pairing, -1, sizeof(bL_switcher_cpu_pairing)); cpumask_copy(&available_cpus, cpu_online_mask); cluster_0 = -1; for_each_cpu(i, &available_cpus) { int match = -1; cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); if (cluster_0 == -1) cluster_0 = cluster; if (cluster != cluster_0) continue; cpumask_clear_cpu(i, &available_cpus); for_each_cpu(j, &available_cpus) { cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(j), 1); /* * Let's remember the last match to create "odd" * pairings on purpose in order for other code not * to assume any relation between physical and * logical CPU numbers. */ if (cluster != cluster_0) match = j; } if (match != -1) { bL_switcher_cpu_pairing[i] = match; cpumask_clear_cpu(match, &available_cpus); pr_info("CPU%d paired with CPU%d\n", i, match); } } /* * Now we disable the unwanted CPUs i.e. everything that has no * pairing information (that includes the pairing counterparts). */ cpumask_clear(&bL_switcher_removed_logical_cpus); for_each_online_cpu(i) { cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0); cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); /* Let's take note of the GIC ID for this CPU */ gic_id = gic_get_cpu_id(i); if (gic_id < 0) { pr_err("%s: bad GIC ID for CPU %d\n", __func__, i); bL_switcher_restore_cpus(); return -EINVAL; } bL_gic_id[cpu][cluster] = gic_id; pr_info("GIC ID for CPU %u cluster %u is %u\n", cpu, cluster, gic_id); if (bL_switcher_cpu_pairing[i] != -1) { bL_switcher_cpu_original_cluster[i] = cluster; continue; } ret = device_offline(get_cpu_device(i)); if (ret) { bL_switcher_restore_cpus(); return ret; } cpumask_set_cpu(i, &bL_switcher_removed_logical_cpus); } return 0; } /* Determine the logical CPU a given physical CPU is grouped on. */ int bL_switcher_get_logical_index(u32 mpidr) { int cpu; if (!bL_switcher_active) return -EUNATCH; mpidr &= MPIDR_HWID_BITMASK; for_each_online_cpu(cpu) { int pairing = bL_switcher_cpu_pairing[cpu]; if (pairing == -1) continue; if ((mpidr == cpu_logical_map(cpu)) || (mpidr == cpu_logical_map(pairing))) return cpu; } return -EINVAL; } static void bL_switcher_trace_trigger_cpu(void *__always_unused info) { trace_cpu_migrate_current(ktime_get_real_ns(), read_mpidr()); } int bL_switcher_trace_trigger(void) { int ret; preempt_disable(); bL_switcher_trace_trigger_cpu(NULL); ret = smp_call_function(bL_switcher_trace_trigger_cpu, NULL, true); preempt_enable(); return ret; } EXPORT_SYMBOL_GPL(bL_switcher_trace_trigger); static int bL_switcher_enable(void) { int cpu, ret; mutex_lock(&bL_switcher_activation_lock); lock_device_hotplug(); if (bL_switcher_active) { unlock_device_hotplug(); mutex_unlock(&bL_switcher_activation_lock); return 0; } pr_info("big.LITTLE switcher initializing\n"); ret = bL_activation_notify(BL_NOTIFY_PRE_ENABLE); if (ret) goto error; ret = bL_switcher_halve_cpus(); if (ret) goto error; bL_switcher_trace_trigger(); for_each_online_cpu(cpu) { struct bL_thread *t = &bL_threads[cpu]; spin_lock_init(&t->lock); init_waitqueue_head(&t->wq); init_completion(&t->started); t->wanted_cluster = -1; t->task = bL_switcher_thread_create(cpu, t); } bL_switcher_active = 1; bL_activation_notify(BL_NOTIFY_POST_ENABLE); pr_info("big.LITTLE switcher initialized\n"); goto out; error: pr_warn("big.LITTLE switcher initialization failed\n"); bL_activation_notify(BL_NOTIFY_POST_DISABLE); out: unlock_device_hotplug(); mutex_unlock(&bL_switcher_activation_lock); return ret; } #ifdef CONFIG_SYSFS static void bL_switcher_disable(void) { unsigned int cpu, cluster; struct bL_thread *t; struct task_struct *task; mutex_lock(&bL_switcher_activation_lock); lock_device_hotplug(); if (!bL_switcher_active) goto out; if (bL_activation_notify(BL_NOTIFY_PRE_DISABLE) != 0) { bL_activation_notify(BL_NOTIFY_POST_ENABLE); goto out; } bL_switcher_active = 0; /* * To deactivate the switcher, we must shut down the switcher * threads to prevent any other requests from being accepted. * Then, if the final cluster for given logical CPU is not the * same as the original one, we'll recreate a switcher thread * just for the purpose of switching the CPU back without any * possibility for interference from external requests. */ for_each_online_cpu(cpu) { t = &bL_threads[cpu]; task = t->task; t->task = NULL; if (!task || IS_ERR(task)) continue; kthread_stop(task); /* no more switch may happen on this CPU at this point */ cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1); if (cluster == bL_switcher_cpu_original_cluster[cpu]) continue; init_completion(&t->started); t->wanted_cluster = bL_switcher_cpu_original_cluster[cpu]; task = bL_switcher_thread_create(cpu, t); if (!IS_ERR(task)) { wait_for_completion(&t->started); kthread_stop(task); cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1); if (cluster == bL_switcher_cpu_original_cluster[cpu]) continue; } /* If execution gets here, we're in trouble. */ pr_crit("%s: unable to restore original cluster for CPU %d\n", __func__, cpu); pr_crit("%s: CPU %d can't be restored\n", __func__, bL_switcher_cpu_pairing[cpu]); cpumask_clear_cpu(bL_switcher_cpu_pairing[cpu], &bL_switcher_removed_logical_cpus); } bL_switcher_restore_cpus(); bL_switcher_trace_trigger(); bL_activation_notify(BL_NOTIFY_POST_DISABLE); out: unlock_device_hotplug(); mutex_unlock(&bL_switcher_activation_lock); } static ssize_t bL_switcher_active_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sprintf(buf, "%u\n", bL_switcher_active); } static ssize_t bL_switcher_active_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { int ret; switch (buf[0]) { case '0': bL_switcher_disable(); ret = 0; break; case '1': ret = bL_switcher_enable(); break; default: ret = -EINVAL; } return (ret >= 0) ? count : ret; } static ssize_t bL_switcher_trace_trigger_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { int ret = bL_switcher_trace_trigger(); return ret ? ret : count; } static struct kobj_attribute bL_switcher_active_attr = __ATTR(active, 0644, bL_switcher_active_show, bL_switcher_active_store); static struct kobj_attribute bL_switcher_trace_trigger_attr = __ATTR(trace_trigger, 0200, NULL, bL_switcher_trace_trigger_store); static struct attribute *bL_switcher_attrs[] = { &bL_switcher_active_attr.attr, &bL_switcher_trace_trigger_attr.attr, NULL, }; static struct attribute_group bL_switcher_attr_group = { .attrs = bL_switcher_attrs, }; static struct kobject *bL_switcher_kobj; static int __init bL_switcher_sysfs_init(void) { int ret; bL_switcher_kobj = kobject_create_and_add("bL_switcher", kernel_kobj); if (!bL_switcher_kobj) return -ENOMEM; ret = sysfs_create_group(bL_switcher_kobj, &bL_switcher_attr_group); if (ret) kobject_put(bL_switcher_kobj); return ret; } #endif /* CONFIG_SYSFS */ bool bL_switcher_get_enabled(void) { mutex_lock(&bL_switcher_activation_lock); return bL_switcher_active; } EXPORT_SYMBOL_GPL(bL_switcher_get_enabled); void bL_switcher_put_enabled(void) { mutex_unlock(&bL_switcher_activation_lock); } EXPORT_SYMBOL_GPL(bL_switcher_put_enabled); /* * Veto any CPU hotplug operation on those CPUs we've removed * while the switcher is active. * We're just not ready to deal with that given the trickery involved. */ static int bL_switcher_cpu_pre(unsigned int cpu) { int pairing; if (!bL_switcher_active) return 0; pairing = bL_switcher_cpu_pairing[cpu]; if (pairing == -1) return -EINVAL; return 0; } static bool no_bL_switcher; core_param(no_bL_switcher, no_bL_switcher, bool, 0644); static int __init bL_switcher_init(void) { int ret; if (!mcpm_is_available()) return -ENODEV; cpuhp_setup_state_nocalls(CPUHP_ARM_BL_PREPARE, "arm/bl:prepare", bL_switcher_cpu_pre, NULL); ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "arm/bl:predown", NULL, bL_switcher_cpu_pre); if (ret < 0) { cpuhp_remove_state_nocalls(CPUHP_ARM_BL_PREPARE); pr_err("bL_switcher: Failed to allocate a hotplug state\n"); return ret; } if (!no_bL_switcher) { ret = bL_switcher_enable(); if (ret) return ret; } #ifdef CONFIG_SYSFS ret = bL_switcher_sysfs_init(); if (ret) pr_err("%s: unable to create sysfs entry\n", __func__); #endif return 0; } late_initcall(bL_switcher_init);
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