/* CPU control. * (C) 2001, 2002, 2003, 2004 Rusty Russell * * This code is licenced under the GPL. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "smpboot.h" #include "sched/sched.h" #ifdef CONFIG_SMP /* Serializes the updates to cpu_online_mask, cpu_present_mask */ static DEFINE_MUTEX(cpu_add_remove_lock); static DEFINE_PER_CPU(bool, booted_once); /* * The following two APIs (cpu_maps_update_begin/done) must be used when * attempting to serialize the updates to cpu_online_mask & cpu_present_mask. * The APIs cpu_notifier_register_begin/done() must be used to protect CPU * hotplug callback (un)registration performed using __register_cpu_notifier() * or __unregister_cpu_notifier(). */ void cpu_maps_update_begin(void) { mutex_lock(&cpu_add_remove_lock); } EXPORT_SYMBOL(cpu_notifier_register_begin); void cpu_maps_update_done(void) { mutex_unlock(&cpu_add_remove_lock); } EXPORT_SYMBOL(cpu_notifier_register_done); static RAW_NOTIFIER_HEAD(cpu_chain); /* If set, cpu_up and cpu_down will return -EBUSY and do nothing. * Should always be manipulated under cpu_add_remove_lock */ static int cpu_hotplug_disabled; #ifdef CONFIG_HOTPLUG_CPU static struct { struct task_struct *active_writer; struct mutex lock; /* Synchronizes accesses to refcount, */ /* * Also blocks the new readers during * an ongoing cpu hotplug operation. */ int refcount; #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map; #endif } cpu_hotplug = { .active_writer = NULL, .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock), .refcount = 0, #ifdef CONFIG_DEBUG_LOCK_ALLOC .dep_map = {.name = "cpu_hotplug.lock" }, #endif }; /* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */ #define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map) #define cpuhp_lock_acquire_tryread() \ lock_map_acquire_tryread(&cpu_hotplug.dep_map) #define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map) #define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map) void get_online_cpus(void) { might_sleep(); if (cpu_hotplug.active_writer == current) return; cpuhp_lock_acquire_read(); mutex_lock(&cpu_hotplug.lock); cpu_hotplug.refcount++; mutex_unlock(&cpu_hotplug.lock); } EXPORT_SYMBOL_GPL(get_online_cpus); bool try_get_online_cpus(void) { if (cpu_hotplug.active_writer == current) return true; if (!mutex_trylock(&cpu_hotplug.lock)) return false; cpuhp_lock_acquire_tryread(); cpu_hotplug.refcount++; mutex_unlock(&cpu_hotplug.lock); return true; } EXPORT_SYMBOL_GPL(try_get_online_cpus); void put_online_cpus(void) { if (cpu_hotplug.active_writer == current) return; mutex_lock(&cpu_hotplug.lock); if (WARN_ON(!cpu_hotplug.refcount)) cpu_hotplug.refcount++; /* try to fix things up */ if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer)) wake_up_process(cpu_hotplug.active_writer); mutex_unlock(&cpu_hotplug.lock); cpuhp_lock_release(); } EXPORT_SYMBOL_GPL(put_online_cpus); #ifdef CONFIG_PROVE_LOCKING /* * The cpu_hotplug structure actually has 2 separate lockdep allocation * debug structures. One is the core dep_map in the structure itself and * the other one is in the cpu_hotplug.lock mutex. The core dep_map is * tracked as a rwlock with get_online_cpus() treated as a read lock and * cpu_hotplug_begin() as a write lock. * * The try_get_online_cpus() can work around potential recursive lock * taking issue reported by lockdep. However, the lockdep structure in * the mutex will still report lockdep error because of the mutex_lock() * in put_online_cpus(). It is actually not a real problem as the success * of try_get_online_cpus() means other cpus cannot start a hotplug event * sequence before put_onlines_cpus(). Other mutex lock holders can only * increment and decrement the reference count which is pretty quick. * * To avoid false positive of this kind, the lockdep tracking in the mutex * itself is turned off. Lockdep tracking will still be done in the core * dep_map structure as a rwlock. */ static int __init disable_cpu_hotplug_mutex_lockdep(void) { lockdep_set_novalidate_class(&cpu_hotplug.lock); return 0; } pure_initcall(disable_cpu_hotplug_mutex_lockdep); #endif /* * This ensures that the hotplug operation can begin only when the * refcount goes to zero. * * Note that during a cpu-hotplug operation, the new readers, if any, * will be blocked by the cpu_hotplug.lock * * Since cpu_hotplug_begin() is always called after invoking * cpu_maps_update_begin(), we can be sure that only one writer is active. * * Note that theoretically, there is a possibility of a livelock: * - Refcount goes to zero, last reader wakes up the sleeping * writer. * - Last reader unlocks the cpu_hotplug.lock. * - A new reader arrives at this moment, bumps up the refcount. * - The writer acquires the cpu_hotplug.lock finds the refcount * non zero and goes to sleep again. * * However, this is very difficult to achieve in practice since * get_online_cpus() not an api which is called all that often. * */ static void cpu_hotplug_begin(void) { cpu_hotplug.active_writer = current; cpuhp_lock_acquire(); for (;;) { mutex_lock(&cpu_hotplug.lock); if (likely(!cpu_hotplug.refcount)) break; __set_current_state(TASK_UNINTERRUPTIBLE); mutex_unlock(&cpu_hotplug.lock); schedule(); } } static void cpu_hotplug_done(void) { cpu_hotplug.active_writer = NULL; mutex_unlock(&cpu_hotplug.lock); cpuhp_lock_release(); } /* * Wait for currently running CPU hotplug operations to complete (if any) and * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the * hotplug path before performing hotplug operations. So acquiring that lock * guarantees mutual exclusion from any currently running hotplug operations. */ void cpu_hotplug_disable(void) { cpu_maps_update_begin(); cpu_hotplug_disabled = 1; cpu_maps_update_done(); } void cpu_hotplug_enable(void) { cpu_maps_update_begin(); cpu_hotplug_disabled = 0; cpu_maps_update_done(); } #else /* #if CONFIG_HOTPLUG_CPU */ static void cpu_hotplug_begin(void) {} static void cpu_hotplug_done(void) {} #endif /* #else #if CONFIG_HOTPLUG_CPU */ /* * Architectures that need SMT-specific errata handling during SMT hotplug * should override this. */ void __weak arch_smt_update(void) { } #ifdef CONFIG_HOTPLUG_SMT enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED; void __init cpu_smt_disable(bool force) { if (cpu_smt_control == CPU_SMT_FORCE_DISABLED || cpu_smt_control == CPU_SMT_NOT_SUPPORTED) return; if (force) { pr_info("SMT: Force disabled\n"); cpu_smt_control = CPU_SMT_FORCE_DISABLED; } else { cpu_smt_control = CPU_SMT_DISABLED; } } /* * The decision whether SMT is supported can only be done after the full * CPU identification. Called from architecture code. */ void __init cpu_smt_check_topology(void) { if (!topology_smt_supported()) cpu_smt_control = CPU_SMT_NOT_SUPPORTED; } static int __init smt_cmdline_disable(char *str) { cpu_smt_disable(str && !strcmp(str, "force")); return 0; } early_param("nosmt", smt_cmdline_disable); bool cpu_smt_allowed(unsigned int cpu) { if (cpu_smt_control == CPU_SMT_ENABLED) return true; if (topology_is_primary_thread(cpu)) return true; /* * On x86 it's required to boot all logical CPUs at least once so * that the init code can get a chance to set CR4.MCE on each * CPU. Otherwise, a broadacasted MCE observing CR4.MCE=0b on any * core will shutdown the machine. */ return !per_cpu(booted_once, cpu); } #endif /* Need to know about CPUs going up/down? */ int __ref register_cpu_notifier(struct notifier_block *nb) { int ret; cpu_maps_update_begin(); ret = raw_notifier_chain_register(&cpu_chain, nb); cpu_maps_update_done(); return ret; } int __ref __register_cpu_notifier(struct notifier_block *nb) { return raw_notifier_chain_register(&cpu_chain, nb); } static int __cpu_notify(unsigned long val, void *v, int nr_to_call, int *nr_calls) { int ret; ret = __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call, nr_calls); return notifier_to_errno(ret); } static int cpu_notify(unsigned long val, void *v) { return __cpu_notify(val, v, -1, NULL); } #ifdef CONFIG_HOTPLUG_CPU static void cpu_notify_nofail(unsigned long val, void *v) { BUG_ON(cpu_notify(val, v)); } EXPORT_SYMBOL(register_cpu_notifier); EXPORT_SYMBOL(__register_cpu_notifier); void __ref unregister_cpu_notifier(struct notifier_block *nb) { cpu_maps_update_begin(); raw_notifier_chain_unregister(&cpu_chain, nb); cpu_maps_update_done(); } EXPORT_SYMBOL(unregister_cpu_notifier); void __ref __unregister_cpu_notifier(struct notifier_block *nb) { raw_notifier_chain_unregister(&cpu_chain, nb); } EXPORT_SYMBOL(__unregister_cpu_notifier); /** * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU * @cpu: a CPU id * * This function walks all processes, finds a valid mm struct for each one and * then clears a corresponding bit in mm's cpumask. While this all sounds * trivial, there are various non-obvious corner cases, which this function * tries to solve in a safe manner. * * Also note that the function uses a somewhat relaxed locking scheme, so it may * be called only for an already offlined CPU. */ void clear_tasks_mm_cpumask(int cpu) { struct task_struct *p; /* * This function is called after the cpu is taken down and marked * offline, so its not like new tasks will ever get this cpu set in * their mm mask. -- Peter Zijlstra * Thus, we may use rcu_read_lock() here, instead of grabbing * full-fledged tasklist_lock. */ WARN_ON(cpu_online(cpu)); rcu_read_lock(); for_each_process(p) { struct task_struct *t; /* * Main thread might exit, but other threads may still have * a valid mm. Find one. */ t = find_lock_task_mm(p); if (!t) continue; cpumask_clear_cpu(cpu, mm_cpumask(t->mm)); task_unlock(t); } rcu_read_unlock(); } static inline void check_for_tasks(int cpu) { struct task_struct *p; cputime_t utime, stime; qwrite_lock_irq(&tasklist_lock); for_each_process(p) { task_cputime(p, &utime, &stime); if (task_cpu(p) == cpu && p->state == TASK_RUNNING && (utime || stime)) printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d " "(state = %ld, flags = %x)\n", p->comm, task_pid_nr(p), cpu, p->state, p->flags); } qwrite_unlock_irq(&tasklist_lock); } struct take_cpu_down_param { unsigned long mod; void *hcpu; }; /* Take this CPU down. */ static int __ref take_cpu_down(void *_param) { struct take_cpu_down_param *param = _param; int err; /* Ensure this CPU doesn't handle any more interrupts. */ err = __cpu_disable(); if (err < 0) return err; cpu_notify(CPU_DYING | param->mod, param->hcpu); /* Park the stopper thread */ stop_machine_park((long)param->hcpu); return 0; } /* Requires cpu_add_remove_lock to be held */ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) { int err, nr_calls = 0; void *hcpu = (void *)(long)cpu; unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0; struct take_cpu_down_param tcd_param = { .mod = mod, .hcpu = hcpu, }; if (num_online_cpus() == 1) return -EBUSY; if (!cpu_online(cpu)) return -EINVAL; /* * The sibling_mask will be cleared in take_cpu_down when the * operation succeeds. So we can't test the sibling mask after * that. We needs to call sched_cpu_activate() if it fails. */ sched_cpu_deactivate(cpu); cpu_hotplug_begin(); err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls); if (err) { nr_calls--; __cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL); printk("%s: attempt to take down CPU %u failed\n", __func__, cpu); goto out_release; } /* * By now we've cleared cpu_active_mask, wait for all preempt-disabled * and RCU users of this state to go away such that all new such users * will observe it. * * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might * not imply sync_sched(), so explicitly call both. * * Do sync before park smpboot threads to take care the rcu boost case. */ #ifdef CONFIG_PREEMPT synchronize_sched(); #endif synchronize_rcu(); smpboot_park_threads(cpu); /* * So now all preempt/rcu users must observe !cpu_active(). */ err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu)); if (err) { /* CPU didn't die: tell everyone. Can't complain. */ smpboot_unpark_threads(cpu); cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu); goto out_release; } BUG_ON(cpu_online(cpu)); /* * The migration_call() CPU_DYING callback will have removed all * runnable tasks from the cpu, there's only the idle task left now * that the migration thread is done doing the stop_machine thing. * * Wait for the stop thread to go away. */ while (!idle_cpu(cpu)) cpu_relax(); hotplug_cpu__broadcast_tick_pull(cpu); /* This actually kills the CPU. */ __cpu_die(cpu); /* CPU is completely dead: tell everyone. Too late to complain. */ cpu_notify_nofail(CPU_DEAD | mod, hcpu); check_for_tasks(cpu); out_release: cpu_hotplug_done(); if (!err) cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu); else sched_cpu_activate(cpu); /* Revert sched_cpu_deactivate() */ arch_smt_update(); return err; } static int cpu_down_maps_locked(unsigned int cpu) { if (cpu_hotplug_disabled) return -EBUSY; return _cpu_down(cpu, 0); } int __ref cpu_down(unsigned int cpu) { int err; cpu_maps_update_begin(); err = cpu_down_maps_locked(cpu); cpu_maps_update_done(); return err; } EXPORT_SYMBOL(cpu_down); #endif /*CONFIG_HOTPLUG_CPU*/ /* Requires cpu_add_remove_lock to be held */ static int _cpu_up(unsigned int cpu, int tasks_frozen) { int ret, nr_calls = 0; void *hcpu = (void *)(long)cpu; unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0; struct task_struct *idle; cpu_hotplug_begin(); if (cpu_online(cpu) || !cpu_present(cpu)) { ret = -EINVAL; goto out; } idle = idle_thread_get(cpu); if (IS_ERR(idle)) { ret = PTR_ERR(idle); goto out; } ret = smpboot_create_threads(cpu); if (ret) goto out; ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls); if (ret) { nr_calls--; printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n", __func__, cpu); goto out_notify; } /* Arch-specific enabling code. */ ret = __cpu_up(cpu, idle); if (ret != 0) goto out_notify; BUG_ON(!cpu_online(cpu)); /* Wake the per cpu threads */ smpboot_unpark_threads(cpu); /* Now call notifier in preparation. */ cpu_notify(CPU_ONLINE | mod, hcpu); out_notify: if (ret != 0) __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL); out: cpu_hotplug_done(); if (!ret) sched_cpu_activate(cpu); arch_smt_update(); return ret; } int cpu_up(unsigned int cpu) { int err = 0; if (!cpu_possible(cpu)) { printk(KERN_ERR "can't online cpu %d because it is not " "configured as may-hotadd at boot time\n", cpu); #if defined(CONFIG_IA64) printk(KERN_ERR "please check additional_cpus= boot " "parameter\n"); #endif return -EINVAL; } err = try_online_node(cpu_to_node(cpu)); if (err) return err; cpu_maps_update_begin(); if (cpu_hotplug_disabled) { err = -EBUSY; goto out; } if (!cpu_smt_allowed(cpu)) { err = -EPERM; goto out; } err = _cpu_up(cpu, 0); out: cpu_maps_update_done(); return err; } EXPORT_SYMBOL_GPL(cpu_up); #ifdef CONFIG_PM_SLEEP_SMP static cpumask_var_t frozen_cpus; int disable_nonboot_cpus(void) { int cpu, first_cpu, error = 0; cpu_maps_update_begin(); first_cpu = cpumask_first(cpu_online_mask); /* * We take down all of the non-boot CPUs in one shot to avoid races * with the userspace trying to use the CPU hotplug at the same time */ cpumask_clear(frozen_cpus); printk("Disabling non-boot CPUs ...\n"); for_each_online_cpu(cpu) { if (cpu == first_cpu) continue; error = _cpu_down(cpu, 1); if (!error) cpumask_set_cpu(cpu, frozen_cpus); else { printk(KERN_ERR "Error taking CPU%d down: %d\n", cpu, error); break; } } if (!error) { BUG_ON(num_online_cpus() > 1); /* Make sure the CPUs won't be enabled by someone else */ cpu_hotplug_disabled = 1; } else { printk(KERN_ERR "Non-boot CPUs are not disabled\n"); } cpu_maps_update_done(); return error; } void __weak arch_enable_nonboot_cpus_begin(void) { } void __weak arch_enable_nonboot_cpus_end(void) { } void __ref enable_nonboot_cpus(void) { int cpu, error; /* Allow everyone to use the CPU hotplug again */ cpu_maps_update_begin(); cpu_hotplug_disabled = 0; if (cpumask_empty(frozen_cpus)) goto out; printk(KERN_INFO "Enabling non-boot CPUs ...\n"); arch_enable_nonboot_cpus_begin(); for_each_cpu(cpu, frozen_cpus) { error = _cpu_up(cpu, 1); if (!error) { printk(KERN_INFO "CPU%d is up\n", cpu); continue; } printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error); } arch_enable_nonboot_cpus_end(); cpumask_clear(frozen_cpus); out: cpu_maps_update_done(); } static int __init alloc_frozen_cpus(void) { if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO)) return -ENOMEM; return 0; } core_initcall(alloc_frozen_cpus); /* * When callbacks for CPU hotplug notifications are being executed, we must * ensure that the state of the system with respect to the tasks being frozen * or not, as reported by the notification, remains unchanged *throughout the * duration* of the execution of the callbacks. * Hence we need to prevent the freezer from racing with regular CPU hotplug. * * This synchronization is implemented by mutually excluding regular CPU * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/ * Hibernate notifications. */ static int cpu_hotplug_pm_callback(struct notifier_block *nb, unsigned long action, void *ptr) { switch (action) { case PM_SUSPEND_PREPARE: case PM_HIBERNATION_PREPARE: cpu_hotplug_disable(); break; case PM_POST_SUSPEND: case PM_POST_HIBERNATION: cpu_hotplug_enable(); break; default: return NOTIFY_DONE; } return NOTIFY_OK; } static int __init cpu_hotplug_pm_sync_init(void) { /* * cpu_hotplug_pm_callback has higher priority than x86 * bsp_pm_callback which depends on cpu_hotplug_pm_callback * to disable cpu hotplug to avoid cpu hotplug race. */ pm_notifier(cpu_hotplug_pm_callback, 0); return 0; } core_initcall(cpu_hotplug_pm_sync_init); #endif /* CONFIG_PM_SLEEP_SMP */ /** * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers * @cpu: cpu that just started * * This function calls the cpu_chain notifiers with CPU_STARTING. * It must be called by the arch code on the new cpu, before the new cpu * enables interrupts and before the "boot" cpu returns from __cpu_up(). */ void notify_cpu_starting(unsigned int cpu) { unsigned long val = CPU_STARTING; per_cpu(booted_once, cpu) = true; #ifdef CONFIG_PM_SLEEP_SMP if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus)) val = CPU_STARTING_FROZEN; #endif /* CONFIG_PM_SLEEP_SMP */ cpu_notify(val, (void *)(long)cpu); } #endif /* CONFIG_SMP */ #if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU) #ifdef CONFIG_HOTPLUG_SMT static void cpuhp_offline_cpu_device(unsigned int cpu) { struct device *dev = get_cpu_device(cpu); dev->offline = true; /* Tell user space about the state change */ kobject_uevent(&dev->kobj, KOBJ_OFFLINE); } static void cpuhp_online_cpu_device(unsigned int cpu) { struct device *dev = get_cpu_device(cpu); dev->offline = false; /* Tell user space about the state change */ kobject_uevent(&dev->kobj, KOBJ_ONLINE); } static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) { int cpu, ret = 0; cpu_maps_update_begin(); for_each_online_cpu(cpu) { if (topology_is_primary_thread(cpu)) continue; ret = cpu_down_maps_locked(cpu); if (ret) break; /* * As this needs to hold the cpu maps lock it's impossible * to call device_offline() because that ends up calling * cpu_down() which takes cpu maps lock. cpu maps lock * needs to be held as this might race against in kernel * abusers of the hotplug machinery (thermal management). * * So nothing would update device:offline state. That would * leave the sysfs entry stale and prevent onlining after * smt control has been changed to 'off' again. This is * called under the sysfs hotplug lock, so it is properly * serialized against the regular offline usage. */ cpuhp_offline_cpu_device(cpu); } if (!ret) cpu_smt_control = ctrlval; cpu_maps_update_done(); return ret; } static int cpuhp_smt_enable(void) { int cpu, ret = 0; cpu_maps_update_begin(); cpu_smt_control = CPU_SMT_ENABLED; for_each_present_cpu(cpu) { /* Skip online CPUs and CPUs on offline nodes */ if (cpu_online(cpu) || !node_online(cpu_to_node(cpu))) continue; ret = _cpu_up(cpu, 0); if (ret) break; /* See comment in cpuhp_smt_disable() */ cpuhp_online_cpu_device(cpu); } cpu_maps_update_done(); return ret; } static ssize_t __store_smt_control(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { int ctrlval, ret; if (sysfs_streq(buf, "on")) ctrlval = CPU_SMT_ENABLED; else if (sysfs_streq(buf, "off")) ctrlval = CPU_SMT_DISABLED; else if (sysfs_streq(buf, "forceoff")) ctrlval = CPU_SMT_FORCE_DISABLED; else return -EINVAL; if (cpu_smt_control == CPU_SMT_FORCE_DISABLED) return -EPERM; if (cpu_smt_control == CPU_SMT_NOT_SUPPORTED) return -ENODEV; ret = lock_device_hotplug_sysfs(); if (ret) return ret; if (ctrlval != cpu_smt_control) { switch (ctrlval) { case CPU_SMT_ENABLED: ret = cpuhp_smt_enable(); break; case CPU_SMT_DISABLED: case CPU_SMT_FORCE_DISABLED: ret = cpuhp_smt_disable(ctrlval); break; } } unlock_device_hotplug(); return ret ? ret : count; } #else /* !CONFIG_HOTPLUG_SMT */ static ssize_t __store_smt_control(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { return -ENODEV; } #endif /* CONFIG_HOTPLUG_SMT */ static const char *smt_states[] = { [CPU_SMT_ENABLED] = "on", [CPU_SMT_DISABLED] = "off", [CPU_SMT_FORCE_DISABLED] = "forceoff", [CPU_SMT_NOT_SUPPORTED] = "notsupported", [CPU_SMT_NOT_IMPLEMENTED] = "notimplemented", }; static ssize_t show_smt_control(struct device *dev, struct device_attribute *attr, char *buf) { const char *state = smt_states[cpu_smt_control]; return snprintf(buf, PAGE_SIZE - 2, "%s\n", state); } static ssize_t store_smt_control(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { return __store_smt_control(dev, attr, buf, count); } static DEVICE_ATTR(control, 0644, show_smt_control, store_smt_control); static ssize_t show_smt_active(struct device *dev, struct device_attribute *attr, char *buf) { return snprintf(buf, PAGE_SIZE - 2, "%d\n", sched_smt_active()); } static DEVICE_ATTR(active, 0444, show_smt_active, NULL); static struct attribute *cpuhp_smt_attrs[] = { &dev_attr_control.attr, &dev_attr_active.attr, NULL }; static const struct attribute_group cpuhp_smt_attr_group = { .attrs = cpuhp_smt_attrs, .name = "smt", NULL }; static int __init cpu_smt_sysfs_init(void) { return sysfs_create_group(&cpu_subsys.dev_root->kobj, &cpuhp_smt_attr_group); } static int __init cpuhp_sysfs_init(void) { return cpu_smt_sysfs_init(); } device_initcall(cpuhp_sysfs_init); #endif /* CONFIG_SYSFS && CONFIG_HOTPLUG_CPU */ /* * cpu_bit_bitmap[] is a special, "compressed" data structure that * represents all NR_CPUS bits binary values of 1< 32 MASK_DECLARE_8(32), MASK_DECLARE_8(40), MASK_DECLARE_8(48), MASK_DECLARE_8(56), #endif }; EXPORT_SYMBOL_GPL(cpu_bit_bitmap); const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL; EXPORT_SYMBOL(cpu_all_bits); #ifdef CONFIG_INIT_ALL_POSSIBLE static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly = CPU_BITS_ALL; #else static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly; #endif const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits); EXPORT_SYMBOL(cpu_possible_mask); static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly; const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits); EXPORT_SYMBOL(cpu_online_mask); static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly; const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits); EXPORT_SYMBOL(cpu_present_mask); static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly; const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits); EXPORT_SYMBOL(cpu_active_mask); void set_cpu_possible(unsigned int cpu, bool possible) { if (possible) cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits)); else cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits)); } void set_cpu_present(unsigned int cpu, bool present) { if (present) cpumask_set_cpu(cpu, to_cpumask(cpu_present_bits)); else cpumask_clear_cpu(cpu, to_cpumask(cpu_present_bits)); } void set_cpu_online(unsigned int cpu, bool online) { if (online) cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits)); else cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits)); } void set_cpu_active(unsigned int cpu, bool active) { if (active) cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits)); else cpumask_clear_cpu(cpu, to_cpumask(cpu_active_bits)); } void reset_cpu_possible_mask(void) { bitmap_zero(cpu_possible_bits, NR_CPUS); } void init_cpu_present(const struct cpumask *src) { cpumask_copy(to_cpumask(cpu_present_bits), src); } void init_cpu_possible(const struct cpumask *src) { cpumask_copy(to_cpumask(cpu_possible_bits), src); } void init_cpu_online(const struct cpumask *src) { cpumask_copy(to_cpumask(cpu_online_bits), src); } void __init boot_cpu_state_init(void) { this_cpu_write(booted_once, true); } /* * These are used for a global "mitigations=" cmdline option for toggling * optional CPU mitigations. */ enum cpu_mitigations { CPU_MITIGATIONS_OFF, CPU_MITIGATIONS_AUTO, CPU_MITIGATIONS_AUTO_NOSMT, }; static enum cpu_mitigations cpu_mitigations __read_mostly = CPU_MITIGATIONS_AUTO; static int __init mitigations_parse_cmdline(char *arg) { if (!strcmp(arg, "off")) cpu_mitigations = CPU_MITIGATIONS_OFF; else if (!strcmp(arg, "auto")) cpu_mitigations = CPU_MITIGATIONS_AUTO; else if (!strcmp(arg, "auto,nosmt")) cpu_mitigations = CPU_MITIGATIONS_AUTO_NOSMT; return 0; } early_param("mitigations", mitigations_parse_cmdline); /* mitigations=off */ bool cpu_mitigations_off(void) { return cpu_mitigations == CPU_MITIGATIONS_OFF; } EXPORT_SYMBOL_GPL(cpu_mitigations_off); /* mitigations=auto,nosmt */ bool cpu_mitigations_auto_nosmt(void) { return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT; } EXPORT_SYMBOL_GPL(cpu_mitigations_auto_nosmt);