v4.19.13 snapshot.
diff --git a/kernel/cpu.c b/kernel/cpu.c
new file mode 100644
index 0000000..1699ff6
--- /dev/null
+++ b/kernel/cpu.c
@@ -0,0 +1,2280 @@
+/* CPU control.
+ * (C) 2001, 2002, 2003, 2004 Rusty Russell
+ *
+ * This code is licenced under the GPL.
+ */
+#include <linux/proc_fs.h>
+#include <linux/smp.h>
+#include <linux/init.h>
+#include <linux/notifier.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/hotplug.h>
+#include <linux/sched/task.h>
+#include <linux/sched/smt.h>
+#include <linux/unistd.h>
+#include <linux/cpu.h>
+#include <linux/oom.h>
+#include <linux/rcupdate.h>
+#include <linux/export.h>
+#include <linux/bug.h>
+#include <linux/kthread.h>
+#include <linux/stop_machine.h>
+#include <linux/mutex.h>
+#include <linux/gfp.h>
+#include <linux/suspend.h>
+#include <linux/lockdep.h>
+#include <linux/tick.h>
+#include <linux/irq.h>
+#include <linux/nmi.h>
+#include <linux/smpboot.h>
+#include <linux/relay.h>
+#include <linux/slab.h>
+#include <linux/percpu-rwsem.h>
+
+#include <trace/events/power.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/cpuhp.h>
+
+#include "smpboot.h"
+
+/**
+ * cpuhp_cpu_state - Per cpu hotplug state storage
+ * @state: The current cpu state
+ * @target: The target state
+ * @thread: Pointer to the hotplug thread
+ * @should_run: Thread should execute
+ * @rollback: Perform a rollback
+ * @single: Single callback invocation
+ * @bringup: Single callback bringup or teardown selector
+ * @cb_state: The state for a single callback (install/uninstall)
+ * @result: Result of the operation
+ * @done_up: Signal completion to the issuer of the task for cpu-up
+ * @done_down: Signal completion to the issuer of the task for cpu-down
+ */
+struct cpuhp_cpu_state {
+ enum cpuhp_state state;
+ enum cpuhp_state target;
+ enum cpuhp_state fail;
+#ifdef CONFIG_SMP
+ struct task_struct *thread;
+ bool should_run;
+ bool rollback;
+ bool single;
+ bool bringup;
+ bool booted_once;
+ struct hlist_node *node;
+ struct hlist_node *last;
+ enum cpuhp_state cb_state;
+ int result;
+ struct completion done_up;
+ struct completion done_down;
+#endif
+};
+
+static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state) = {
+ .fail = CPUHP_INVALID,
+};
+
+#if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP)
+static struct lockdep_map cpuhp_state_up_map =
+ STATIC_LOCKDEP_MAP_INIT("cpuhp_state-up", &cpuhp_state_up_map);
+static struct lockdep_map cpuhp_state_down_map =
+ STATIC_LOCKDEP_MAP_INIT("cpuhp_state-down", &cpuhp_state_down_map);
+
+
+static inline void cpuhp_lock_acquire(bool bringup)
+{
+ lock_map_acquire(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map);
+}
+
+static inline void cpuhp_lock_release(bool bringup)
+{
+ lock_map_release(bringup ? &cpuhp_state_up_map : &cpuhp_state_down_map);
+}
+#else
+
+static inline void cpuhp_lock_acquire(bool bringup) { }
+static inline void cpuhp_lock_release(bool bringup) { }
+
+#endif
+
+/**
+ * cpuhp_step - Hotplug state machine step
+ * @name: Name of the step
+ * @startup: Startup function of the step
+ * @teardown: Teardown function of the step
+ * @cant_stop: Bringup/teardown can't be stopped at this step
+ */
+struct cpuhp_step {
+ const char *name;
+ union {
+ int (*single)(unsigned int cpu);
+ int (*multi)(unsigned int cpu,
+ struct hlist_node *node);
+ } startup;
+ union {
+ int (*single)(unsigned int cpu);
+ int (*multi)(unsigned int cpu,
+ struct hlist_node *node);
+ } teardown;
+ struct hlist_head list;
+ bool cant_stop;
+ bool multi_instance;
+};
+
+static DEFINE_MUTEX(cpuhp_state_mutex);
+static struct cpuhp_step cpuhp_hp_states[];
+
+static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
+{
+ return cpuhp_hp_states + state;
+}
+
+/**
+ * cpuhp_invoke_callback _ Invoke the callbacks for a given state
+ * @cpu: The cpu for which the callback should be invoked
+ * @state: The state to do callbacks for
+ * @bringup: True if the bringup callback should be invoked
+ * @node: For multi-instance, do a single entry callback for install/remove
+ * @lastp: For multi-instance rollback, remember how far we got
+ *
+ * Called from cpu hotplug and from the state register machinery.
+ */
+static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,
+ bool bringup, struct hlist_node *node,
+ struct hlist_node **lastp)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ struct cpuhp_step *step = cpuhp_get_step(state);
+ int (*cbm)(unsigned int cpu, struct hlist_node *node);
+ int (*cb)(unsigned int cpu);
+ int ret, cnt;
+
+ if (st->fail == state) {
+ st->fail = CPUHP_INVALID;
+
+ if (!(bringup ? step->startup.single : step->teardown.single))
+ return 0;
+
+ return -EAGAIN;
+ }
+
+ if (!step->multi_instance) {
+ WARN_ON_ONCE(lastp && *lastp);
+ cb = bringup ? step->startup.single : step->teardown.single;
+ if (!cb)
+ return 0;
+ trace_cpuhp_enter(cpu, st->target, state, cb);
+ ret = cb(cpu);
+ trace_cpuhp_exit(cpu, st->state, state, ret);
+ return ret;
+ }
+ cbm = bringup ? step->startup.multi : step->teardown.multi;
+ if (!cbm)
+ return 0;
+
+ /* Single invocation for instance add/remove */
+ if (node) {
+ WARN_ON_ONCE(lastp && *lastp);
+ trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
+ ret = cbm(cpu, node);
+ trace_cpuhp_exit(cpu, st->state, state, ret);
+ return ret;
+ }
+
+ /* State transition. Invoke on all instances */
+ cnt = 0;
+ hlist_for_each(node, &step->list) {
+ if (lastp && node == *lastp)
+ break;
+
+ trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
+ ret = cbm(cpu, node);
+ trace_cpuhp_exit(cpu, st->state, state, ret);
+ if (ret) {
+ if (!lastp)
+ goto err;
+
+ *lastp = node;
+ return ret;
+ }
+ cnt++;
+ }
+ if (lastp)
+ *lastp = NULL;
+ return 0;
+err:
+ /* Rollback the instances if one failed */
+ cbm = !bringup ? step->startup.multi : step->teardown.multi;
+ if (!cbm)
+ return ret;
+
+ hlist_for_each(node, &step->list) {
+ if (!cnt--)
+ break;
+
+ trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
+ ret = cbm(cpu, node);
+ trace_cpuhp_exit(cpu, st->state, state, ret);
+ /*
+ * Rollback must not fail,
+ */
+ WARN_ON_ONCE(ret);
+ }
+ return ret;
+}
+
+#ifdef CONFIG_SMP
+static bool cpuhp_is_ap_state(enum cpuhp_state state)
+{
+ /*
+ * The extra check for CPUHP_TEARDOWN_CPU is only for documentation
+ * purposes as that state is handled explicitly in cpu_down.
+ */
+ return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU;
+}
+
+static inline void wait_for_ap_thread(struct cpuhp_cpu_state *st, bool bringup)
+{
+ struct completion *done = bringup ? &st->done_up : &st->done_down;
+ wait_for_completion(done);
+}
+
+static inline void complete_ap_thread(struct cpuhp_cpu_state *st, bool bringup)
+{
+ struct completion *done = bringup ? &st->done_up : &st->done_down;
+ complete(done);
+}
+
+/*
+ * The former STARTING/DYING states, ran with IRQs disabled and must not fail.
+ */
+static bool cpuhp_is_atomic_state(enum cpuhp_state state)
+{
+ return CPUHP_AP_IDLE_DEAD <= state && state < CPUHP_AP_ONLINE;
+}
+
+/* Serializes the updates to cpu_online_mask, cpu_present_mask */
+static DEFINE_MUTEX(cpu_add_remove_lock);
+bool cpuhp_tasks_frozen;
+EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen);
+
+/*
+ * 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.
+ */
+void cpu_maps_update_begin(void)
+{
+ mutex_lock(&cpu_add_remove_lock);
+}
+
+void cpu_maps_update_done(void)
+{
+ mutex_unlock(&cpu_add_remove_lock);
+}
+
+/*
+ * 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
+
+DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock);
+
+void cpus_read_lock(void)
+{
+ percpu_down_read(&cpu_hotplug_lock);
+}
+EXPORT_SYMBOL_GPL(cpus_read_lock);
+
+int cpus_read_trylock(void)
+{
+ return percpu_down_read_trylock(&cpu_hotplug_lock);
+}
+EXPORT_SYMBOL_GPL(cpus_read_trylock);
+
+void cpus_read_unlock(void)
+{
+ percpu_up_read(&cpu_hotplug_lock);
+}
+EXPORT_SYMBOL_GPL(cpus_read_unlock);
+
+void cpus_write_lock(void)
+{
+ percpu_down_write(&cpu_hotplug_lock);
+}
+
+void cpus_write_unlock(void)
+{
+ percpu_up_write(&cpu_hotplug_lock);
+}
+
+void lockdep_assert_cpus_held(void)
+{
+ percpu_rwsem_assert_held(&cpu_hotplug_lock);
+}
+
+/*
+ * 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++;
+ cpu_maps_update_done();
+}
+EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
+
+static void __cpu_hotplug_enable(void)
+{
+ if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
+ return;
+ cpu_hotplug_disabled--;
+}
+
+void cpu_hotplug_enable(void)
+{
+ cpu_maps_update_begin();
+ __cpu_hotplug_enable();
+ cpu_maps_update_done();
+}
+EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
+#endif /* 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;
+EXPORT_SYMBOL_GPL(cpu_smt_control);
+
+static bool cpu_smt_available __read_mostly;
+
+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 before non boot CPUs
+ * are brought up.
+ */
+void __init cpu_smt_check_topology_early(void)
+{
+ if (!topology_smt_supported())
+ cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
+}
+
+/*
+ * If SMT was disabled by BIOS, detect it here, after the CPUs have been
+ * brought online. This ensures the smt/l1tf sysfs entries are consistent
+ * with reality. cpu_smt_available is set to true during the bringup of non
+ * boot CPUs when a SMT sibling is detected. Note, this may overwrite
+ * cpu_smt_control's previous setting.
+ */
+void __init cpu_smt_check_topology(void)
+{
+ if (!cpu_smt_available)
+ 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);
+
+static inline bool cpu_smt_allowed(unsigned int cpu)
+{
+ if (topology_is_primary_thread(cpu))
+ return true;
+
+ /*
+ * If the CPU is not a 'primary' thread and the booted_once bit is
+ * set then the processor has SMT support. Store this information
+ * for the late check of SMT support in cpu_smt_check_topology().
+ */
+ if (per_cpu(cpuhp_state, cpu).booted_once)
+ cpu_smt_available = true;
+
+ if (cpu_smt_control == CPU_SMT_ENABLED)
+ 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(cpuhp_state, cpu).booted_once;
+}
+#else
+static inline bool cpu_smt_allowed(unsigned int cpu) { return true; }
+#endif
+
+static inline enum cpuhp_state
+cpuhp_set_state(struct cpuhp_cpu_state *st, enum cpuhp_state target)
+{
+ enum cpuhp_state prev_state = st->state;
+
+ st->rollback = false;
+ st->last = NULL;
+
+ st->target = target;
+ st->single = false;
+ st->bringup = st->state < target;
+
+ return prev_state;
+}
+
+static inline void
+cpuhp_reset_state(struct cpuhp_cpu_state *st, enum cpuhp_state prev_state)
+{
+ st->rollback = true;
+
+ /*
+ * If we have st->last we need to undo partial multi_instance of this
+ * state first. Otherwise start undo at the previous state.
+ */
+ if (!st->last) {
+ if (st->bringup)
+ st->state--;
+ else
+ st->state++;
+ }
+
+ st->target = prev_state;
+ st->bringup = !st->bringup;
+}
+
+/* Regular hotplug invocation of the AP hotplug thread */
+static void __cpuhp_kick_ap(struct cpuhp_cpu_state *st)
+{
+ if (!st->single && st->state == st->target)
+ return;
+
+ st->result = 0;
+ /*
+ * Make sure the above stores are visible before should_run becomes
+ * true. Paired with the mb() above in cpuhp_thread_fun()
+ */
+ smp_mb();
+ st->should_run = true;
+ wake_up_process(st->thread);
+ wait_for_ap_thread(st, st->bringup);
+}
+
+static int cpuhp_kick_ap(struct cpuhp_cpu_state *st, enum cpuhp_state target)
+{
+ enum cpuhp_state prev_state;
+ int ret;
+
+ prev_state = cpuhp_set_state(st, target);
+ __cpuhp_kick_ap(st);
+ if ((ret = st->result)) {
+ cpuhp_reset_state(st, prev_state);
+ __cpuhp_kick_ap(st);
+ }
+
+ return ret;
+}
+
+static int bringup_wait_for_ap(unsigned int cpu)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+
+ /* Wait for the CPU to reach CPUHP_AP_ONLINE_IDLE */
+ wait_for_ap_thread(st, true);
+ if (WARN_ON_ONCE((!cpu_online(cpu))))
+ return -ECANCELED;
+
+ /* Unpark the stopper thread and the hotplug thread of the target cpu */
+ stop_machine_unpark(cpu);
+ kthread_unpark(st->thread);
+
+ /*
+ * SMT soft disabling on X86 requires to bring the CPU out of the
+ * BIOS 'wait for SIPI' state in order to set the CR4.MCE bit. The
+ * CPU marked itself as booted_once in cpu_notify_starting() so the
+ * cpu_smt_allowed() check will now return false if this is not the
+ * primary sibling.
+ */
+ if (!cpu_smt_allowed(cpu))
+ return -ECANCELED;
+
+ if (st->target <= CPUHP_AP_ONLINE_IDLE)
+ return 0;
+
+ return cpuhp_kick_ap(st, st->target);
+}
+
+static int bringup_cpu(unsigned int cpu)
+{
+ struct task_struct *idle = idle_thread_get(cpu);
+ int ret;
+
+ /*
+ * Some architectures have to walk the irq descriptors to
+ * setup the vector space for the cpu which comes online.
+ * Prevent irq alloc/free across the bringup.
+ */
+ irq_lock_sparse();
+
+ /* Arch-specific enabling code. */
+ ret = __cpu_up(cpu, idle);
+ irq_unlock_sparse();
+ if (ret)
+ return ret;
+ return bringup_wait_for_ap(cpu);
+}
+
+/*
+ * Hotplug state machine related functions
+ */
+
+static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st)
+{
+ for (st->state--; st->state > st->target; st->state--)
+ cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
+}
+
+static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
+ enum cpuhp_state target)
+{
+ enum cpuhp_state prev_state = st->state;
+ int ret = 0;
+
+ while (st->state < target) {
+ st->state++;
+ ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);
+ if (ret) {
+ st->target = prev_state;
+ undo_cpu_up(cpu, st);
+ break;
+ }
+ }
+ return ret;
+}
+
+/*
+ * The cpu hotplug threads manage the bringup and teardown of the cpus
+ */
+static void cpuhp_create(unsigned int cpu)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+
+ init_completion(&st->done_up);
+ init_completion(&st->done_down);
+}
+
+static int cpuhp_should_run(unsigned int cpu)
+{
+ struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
+
+ return st->should_run;
+}
+
+/*
+ * Execute teardown/startup callbacks on the plugged cpu. Also used to invoke
+ * callbacks when a state gets [un]installed at runtime.
+ *
+ * Each invocation of this function by the smpboot thread does a single AP
+ * state callback.
+ *
+ * It has 3 modes of operation:
+ * - single: runs st->cb_state
+ * - up: runs ++st->state, while st->state < st->target
+ * - down: runs st->state--, while st->state > st->target
+ *
+ * When complete or on error, should_run is cleared and the completion is fired.
+ */
+static void cpuhp_thread_fun(unsigned int cpu)
+{
+ struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
+ bool bringup = st->bringup;
+ enum cpuhp_state state;
+
+ if (WARN_ON_ONCE(!st->should_run))
+ return;
+
+ /*
+ * ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures
+ * that if we see ->should_run we also see the rest of the state.
+ */
+ smp_mb();
+
+ cpuhp_lock_acquire(bringup);
+
+ if (st->single) {
+ state = st->cb_state;
+ st->should_run = false;
+ } else {
+ if (bringup) {
+ st->state++;
+ state = st->state;
+ st->should_run = (st->state < st->target);
+ WARN_ON_ONCE(st->state > st->target);
+ } else {
+ state = st->state;
+ st->state--;
+ st->should_run = (st->state > st->target);
+ WARN_ON_ONCE(st->state < st->target);
+ }
+ }
+
+ WARN_ON_ONCE(!cpuhp_is_ap_state(state));
+
+ if (cpuhp_is_atomic_state(state)) {
+ local_irq_disable();
+ st->result = cpuhp_invoke_callback(cpu, state, bringup, st->node, &st->last);
+ local_irq_enable();
+
+ /*
+ * STARTING/DYING must not fail!
+ */
+ WARN_ON_ONCE(st->result);
+ } else {
+ st->result = cpuhp_invoke_callback(cpu, state, bringup, st->node, &st->last);
+ }
+
+ if (st->result) {
+ /*
+ * If we fail on a rollback, we're up a creek without no
+ * paddle, no way forward, no way back. We loose, thanks for
+ * playing.
+ */
+ WARN_ON_ONCE(st->rollback);
+ st->should_run = false;
+ }
+
+ cpuhp_lock_release(bringup);
+
+ if (!st->should_run)
+ complete_ap_thread(st, bringup);
+}
+
+/* Invoke a single callback on a remote cpu */
+static int
+cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state, bool bringup,
+ struct hlist_node *node)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ int ret;
+
+ if (!cpu_online(cpu))
+ return 0;
+
+ cpuhp_lock_acquire(false);
+ cpuhp_lock_release(false);
+
+ cpuhp_lock_acquire(true);
+ cpuhp_lock_release(true);
+
+ /*
+ * If we are up and running, use the hotplug thread. For early calls
+ * we invoke the thread function directly.
+ */
+ if (!st->thread)
+ return cpuhp_invoke_callback(cpu, state, bringup, node, NULL);
+
+ st->rollback = false;
+ st->last = NULL;
+
+ st->node = node;
+ st->bringup = bringup;
+ st->cb_state = state;
+ st->single = true;
+
+ __cpuhp_kick_ap(st);
+
+ /*
+ * If we failed and did a partial, do a rollback.
+ */
+ if ((ret = st->result) && st->last) {
+ st->rollback = true;
+ st->bringup = !bringup;
+
+ __cpuhp_kick_ap(st);
+ }
+
+ /*
+ * Clean up the leftovers so the next hotplug operation wont use stale
+ * data.
+ */
+ st->node = st->last = NULL;
+ return ret;
+}
+
+static int cpuhp_kick_ap_work(unsigned int cpu)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ enum cpuhp_state prev_state = st->state;
+ int ret;
+
+ cpuhp_lock_acquire(false);
+ cpuhp_lock_release(false);
+
+ cpuhp_lock_acquire(true);
+ cpuhp_lock_release(true);
+
+ trace_cpuhp_enter(cpu, st->target, prev_state, cpuhp_kick_ap_work);
+ ret = cpuhp_kick_ap(st, st->target);
+ trace_cpuhp_exit(cpu, st->state, prev_state, ret);
+
+ return ret;
+}
+
+static struct smp_hotplug_thread cpuhp_threads = {
+ .store = &cpuhp_state.thread,
+ .create = &cpuhp_create,
+ .thread_should_run = cpuhp_should_run,
+ .thread_fn = cpuhp_thread_fun,
+ .thread_comm = "cpuhp/%u",
+ .selfparking = true,
+};
+
+void __init cpuhp_threads_init(void)
+{
+ BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads));
+ kthread_unpark(this_cpu_read(cpuhp_state.thread));
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+/**
+ * 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();
+}
+
+/* Take this CPU down. */
+static int take_cpu_down(void *_param)
+{
+ struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
+ enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE);
+ int err, cpu = smp_processor_id();
+ int ret;
+
+ /* Ensure this CPU doesn't handle any more interrupts. */
+ err = __cpu_disable();
+ if (err < 0)
+ return err;
+
+ /*
+ * We get here while we are in CPUHP_TEARDOWN_CPU state and we must not
+ * do this step again.
+ */
+ WARN_ON(st->state != CPUHP_TEARDOWN_CPU);
+ st->state--;
+ /* Invoke the former CPU_DYING callbacks */
+ for (; st->state > target; st->state--) {
+ ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
+ /*
+ * DYING must not fail!
+ */
+ WARN_ON_ONCE(ret);
+ }
+
+ /* Give up timekeeping duties */
+ tick_handover_do_timer();
+ /* Park the stopper thread */
+ stop_machine_park(cpu);
+ return 0;
+}
+
+static int takedown_cpu(unsigned int cpu)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ int err;
+
+ /* Park the smpboot threads */
+ kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread);
+
+ /*
+ * Prevent irq alloc/free while the dying cpu reorganizes the
+ * interrupt affinities.
+ */
+ irq_lock_sparse();
+
+ /*
+ * So now all preempt/rcu users must observe !cpu_active().
+ */
+ err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu));
+ if (err) {
+ /* CPU refused to die */
+ irq_unlock_sparse();
+ /* Unpark the hotplug thread so we can rollback there */
+ kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread);
+ return err;
+ }
+ BUG_ON(cpu_online(cpu));
+
+ /*
+ * The teardown callback for CPUHP_AP_SCHED_STARTING 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.
+ */
+ wait_for_ap_thread(st, false);
+ BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
+
+ /* Interrupts are moved away from the dying cpu, reenable alloc/free */
+ irq_unlock_sparse();
+
+ hotplug_cpu__broadcast_tick_pull(cpu);
+ /* This actually kills the CPU. */
+ __cpu_die(cpu);
+
+ tick_cleanup_dead_cpu(cpu);
+ rcutree_migrate_callbacks(cpu);
+ return 0;
+}
+
+static void cpuhp_complete_idle_dead(void *arg)
+{
+ struct cpuhp_cpu_state *st = arg;
+
+ complete_ap_thread(st, false);
+}
+
+void cpuhp_report_idle_dead(void)
+{
+ struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
+
+ BUG_ON(st->state != CPUHP_AP_OFFLINE);
+ rcu_report_dead(smp_processor_id());
+ st->state = CPUHP_AP_IDLE_DEAD;
+ /*
+ * We cannot call complete after rcu_report_dead() so we delegate it
+ * to an online cpu.
+ */
+ smp_call_function_single(cpumask_first(cpu_online_mask),
+ cpuhp_complete_idle_dead, st, 0);
+}
+
+static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st)
+{
+ for (st->state++; st->state < st->target; st->state++)
+ cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);
+}
+
+static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
+ enum cpuhp_state target)
+{
+ enum cpuhp_state prev_state = st->state;
+ int ret = 0;
+
+ for (; st->state > target; st->state--) {
+ ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
+ if (ret) {
+ st->target = prev_state;
+ if (st->state < prev_state)
+ undo_cpu_down(cpu, st);
+ break;
+ }
+ }
+ return ret;
+}
+
+/* Requires cpu_add_remove_lock to be held */
+static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
+ enum cpuhp_state target)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ int prev_state, ret = 0;
+
+ if (num_online_cpus() == 1)
+ return -EBUSY;
+
+ if (!cpu_present(cpu))
+ return -EINVAL;
+
+ cpus_write_lock();
+
+ cpuhp_tasks_frozen = tasks_frozen;
+
+ prev_state = cpuhp_set_state(st, target);
+ /*
+ * If the current CPU state is in the range of the AP hotplug thread,
+ * then we need to kick the thread.
+ */
+ if (st->state > CPUHP_TEARDOWN_CPU) {
+ st->target = max((int)target, CPUHP_TEARDOWN_CPU);
+ ret = cpuhp_kick_ap_work(cpu);
+ /*
+ * The AP side has done the error rollback already. Just
+ * return the error code..
+ */
+ if (ret)
+ goto out;
+
+ /*
+ * We might have stopped still in the range of the AP hotplug
+ * thread. Nothing to do anymore.
+ */
+ if (st->state > CPUHP_TEARDOWN_CPU)
+ goto out;
+
+ st->target = target;
+ }
+ /*
+ * The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need
+ * to do the further cleanups.
+ */
+ ret = cpuhp_down_callbacks(cpu, st, target);
+ if (ret && st->state == CPUHP_TEARDOWN_CPU && st->state < prev_state) {
+ cpuhp_reset_state(st, prev_state);
+ __cpuhp_kick_ap(st);
+ }
+
+out:
+ cpus_write_unlock();
+ /*
+ * Do post unplug cleanup. This is still protected against
+ * concurrent CPU hotplug via cpu_add_remove_lock.
+ */
+ lockup_detector_cleanup();
+ arch_smt_update();
+ return ret;
+}
+
+static int cpu_down_maps_locked(unsigned int cpu, enum cpuhp_state target)
+{
+ if (cpu_hotplug_disabled)
+ return -EBUSY;
+ return _cpu_down(cpu, 0, target);
+}
+
+static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
+{
+ int err;
+
+ cpu_maps_update_begin();
+ err = cpu_down_maps_locked(cpu, target);
+ cpu_maps_update_done();
+ return err;
+}
+
+int cpu_down(unsigned int cpu)
+{
+ return do_cpu_down(cpu, CPUHP_OFFLINE);
+}
+EXPORT_SYMBOL(cpu_down);
+
+#else
+#define takedown_cpu NULL
+#endif /*CONFIG_HOTPLUG_CPU*/
+
+/**
+ * notify_cpu_starting(cpu) - Invoke the callbacks on the starting CPU
+ * @cpu: cpu that just started
+ *
+ * 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)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
+ int ret;
+
+ rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */
+ st->booted_once = true;
+ while (st->state < target) {
+ st->state++;
+ ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);
+ /*
+ * STARTING must not fail!
+ */
+ WARN_ON_ONCE(ret);
+ }
+}
+
+/*
+ * Called from the idle task. Wake up the controlling task which brings the
+ * stopper and the hotplug thread of the upcoming CPU up and then delegates
+ * the rest of the online bringup to the hotplug thread.
+ */
+void cpuhp_online_idle(enum cpuhp_state state)
+{
+ struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
+
+ /* Happens for the boot cpu */
+ if (state != CPUHP_AP_ONLINE_IDLE)
+ return;
+
+ st->state = CPUHP_AP_ONLINE_IDLE;
+ complete_ap_thread(st, true);
+}
+
+/* Requires cpu_add_remove_lock to be held */
+static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ struct task_struct *idle;
+ int ret = 0;
+
+ cpus_write_lock();
+
+ if (!cpu_present(cpu)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /*
+ * The caller of do_cpu_up might have raced with another
+ * caller. Ignore it for now.
+ */
+ if (st->state >= target)
+ goto out;
+
+ if (st->state == CPUHP_OFFLINE) {
+ /* Let it fail before we try to bring the cpu up */
+ idle = idle_thread_get(cpu);
+ if (IS_ERR(idle)) {
+ ret = PTR_ERR(idle);
+ goto out;
+ }
+ }
+
+ cpuhp_tasks_frozen = tasks_frozen;
+
+ cpuhp_set_state(st, target);
+ /*
+ * If the current CPU state is in the range of the AP hotplug thread,
+ * then we need to kick the thread once more.
+ */
+ if (st->state > CPUHP_BRINGUP_CPU) {
+ ret = cpuhp_kick_ap_work(cpu);
+ /*
+ * The AP side has done the error rollback already. Just
+ * return the error code..
+ */
+ if (ret)
+ goto out;
+ }
+
+ /*
+ * Try to reach the target state. We max out on the BP at
+ * CPUHP_BRINGUP_CPU. After that the AP hotplug thread is
+ * responsible for bringing it up to the target state.
+ */
+ target = min((int)target, CPUHP_BRINGUP_CPU);
+ ret = cpuhp_up_callbacks(cpu, st, target);
+out:
+ cpus_write_unlock();
+ arch_smt_update();
+ return ret;
+}
+
+static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
+{
+ int err = 0;
+
+ if (!cpu_possible(cpu)) {
+ pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
+ cpu);
+#if defined(CONFIG_IA64)
+ pr_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, target);
+out:
+ cpu_maps_update_done();
+ return err;
+}
+
+int cpu_up(unsigned int cpu)
+{
+ return do_cpu_up(cpu, CPUHP_ONLINE);
+}
+EXPORT_SYMBOL_GPL(cpu_up);
+
+#ifdef CONFIG_PM_SLEEP_SMP
+static cpumask_var_t frozen_cpus;
+
+int freeze_secondary_cpus(int primary)
+{
+ int cpu, error = 0;
+
+ cpu_maps_update_begin();
+ if (!cpu_online(primary))
+ primary = 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);
+
+ pr_info("Disabling non-boot CPUs ...\n");
+ for_each_online_cpu(cpu) {
+ if (cpu == primary)
+ continue;
+ trace_suspend_resume(TPS("CPU_OFF"), cpu, true);
+ error = _cpu_down(cpu, 1, CPUHP_OFFLINE);
+ trace_suspend_resume(TPS("CPU_OFF"), cpu, false);
+ if (!error)
+ cpumask_set_cpu(cpu, frozen_cpus);
+ else {
+ pr_err("Error taking CPU%d down: %d\n", cpu, error);
+ break;
+ }
+ }
+
+ if (!error)
+ BUG_ON(num_online_cpus() > 1);
+ else
+ pr_err("Non-boot CPUs are not disabled\n");
+
+ /*
+ * Make sure the CPUs won't be enabled by someone else. We need to do
+ * this even in case of failure as all disable_nonboot_cpus() users are
+ * supposed to do enable_nonboot_cpus() on the failure path.
+ */
+ cpu_hotplug_disabled++;
+
+ cpu_maps_update_done();
+ return error;
+}
+
+void __weak arch_enable_nonboot_cpus_begin(void)
+{
+}
+
+void __weak arch_enable_nonboot_cpus_end(void)
+{
+}
+
+void enable_nonboot_cpus(void)
+{
+ int cpu, error;
+
+ /* Allow everyone to use the CPU hotplug again */
+ cpu_maps_update_begin();
+ __cpu_hotplug_enable();
+ if (cpumask_empty(frozen_cpus))
+ goto out;
+
+ pr_info("Enabling non-boot CPUs ...\n");
+
+ arch_enable_nonboot_cpus_begin();
+
+ for_each_cpu(cpu, frozen_cpus) {
+ trace_suspend_resume(TPS("CPU_ON"), cpu, true);
+ error = _cpu_up(cpu, 1, CPUHP_ONLINE);
+ trace_suspend_resume(TPS("CPU_ON"), cpu, false);
+ if (!error) {
+ pr_info("CPU%d is up\n", cpu);
+ continue;
+ }
+ pr_warn("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 */
+
+int __boot_cpu_id;
+
+#endif /* CONFIG_SMP */
+
+/* Boot processor state steps */
+static struct cpuhp_step cpuhp_hp_states[] = {
+ [CPUHP_OFFLINE] = {
+ .name = "offline",
+ .startup.single = NULL,
+ .teardown.single = NULL,
+ },
+#ifdef CONFIG_SMP
+ [CPUHP_CREATE_THREADS]= {
+ .name = "threads:prepare",
+ .startup.single = smpboot_create_threads,
+ .teardown.single = NULL,
+ .cant_stop = true,
+ },
+ [CPUHP_PERF_PREPARE] = {
+ .name = "perf:prepare",
+ .startup.single = perf_event_init_cpu,
+ .teardown.single = perf_event_exit_cpu,
+ },
+ [CPUHP_WORKQUEUE_PREP] = {
+ .name = "workqueue:prepare",
+ .startup.single = workqueue_prepare_cpu,
+ .teardown.single = NULL,
+ },
+ [CPUHP_HRTIMERS_PREPARE] = {
+ .name = "hrtimers:prepare",
+ .startup.single = hrtimers_prepare_cpu,
+ .teardown.single = hrtimers_dead_cpu,
+ },
+ [CPUHP_SMPCFD_PREPARE] = {
+ .name = "smpcfd:prepare",
+ .startup.single = smpcfd_prepare_cpu,
+ .teardown.single = smpcfd_dead_cpu,
+ },
+ [CPUHP_RELAY_PREPARE] = {
+ .name = "relay:prepare",
+ .startup.single = relay_prepare_cpu,
+ .teardown.single = NULL,
+ },
+ [CPUHP_SLAB_PREPARE] = {
+ .name = "slab:prepare",
+ .startup.single = slab_prepare_cpu,
+ .teardown.single = slab_dead_cpu,
+ },
+ [CPUHP_RCUTREE_PREP] = {
+ .name = "RCU/tree:prepare",
+ .startup.single = rcutree_prepare_cpu,
+ .teardown.single = rcutree_dead_cpu,
+ },
+ /*
+ * On the tear-down path, timers_dead_cpu() must be invoked
+ * before blk_mq_queue_reinit_notify() from notify_dead(),
+ * otherwise a RCU stall occurs.
+ */
+ [CPUHP_TIMERS_PREPARE] = {
+ .name = "timers:prepare",
+ .startup.single = timers_prepare_cpu,
+ .teardown.single = timers_dead_cpu,
+ },
+ /* Kicks the plugged cpu into life */
+ [CPUHP_BRINGUP_CPU] = {
+ .name = "cpu:bringup",
+ .startup.single = bringup_cpu,
+ .teardown.single = NULL,
+ .cant_stop = true,
+ },
+ /* Final state before CPU kills itself */
+ [CPUHP_AP_IDLE_DEAD] = {
+ .name = "idle:dead",
+ },
+ /*
+ * Last state before CPU enters the idle loop to die. Transient state
+ * for synchronization.
+ */
+ [CPUHP_AP_OFFLINE] = {
+ .name = "ap:offline",
+ .cant_stop = true,
+ },
+ /* First state is scheduler control. Interrupts are disabled */
+ [CPUHP_AP_SCHED_STARTING] = {
+ .name = "sched:starting",
+ .startup.single = sched_cpu_starting,
+ .teardown.single = sched_cpu_dying,
+ },
+ [CPUHP_AP_RCUTREE_DYING] = {
+ .name = "RCU/tree:dying",
+ .startup.single = NULL,
+ .teardown.single = rcutree_dying_cpu,
+ },
+ [CPUHP_AP_SMPCFD_DYING] = {
+ .name = "smpcfd:dying",
+ .startup.single = NULL,
+ .teardown.single = smpcfd_dying_cpu,
+ },
+ /* Entry state on starting. Interrupts enabled from here on. Transient
+ * state for synchronsization */
+ [CPUHP_AP_ONLINE] = {
+ .name = "ap:online",
+ },
+ /*
+ * Handled on controll processor until the plugged processor manages
+ * this itself.
+ */
+ [CPUHP_TEARDOWN_CPU] = {
+ .name = "cpu:teardown",
+ .startup.single = NULL,
+ .teardown.single = takedown_cpu,
+ .cant_stop = true,
+ },
+ /* Handle smpboot threads park/unpark */
+ [CPUHP_AP_SMPBOOT_THREADS] = {
+ .name = "smpboot/threads:online",
+ .startup.single = smpboot_unpark_threads,
+ .teardown.single = smpboot_park_threads,
+ },
+ [CPUHP_AP_IRQ_AFFINITY_ONLINE] = {
+ .name = "irq/affinity:online",
+ .startup.single = irq_affinity_online_cpu,
+ .teardown.single = NULL,
+ },
+ [CPUHP_AP_PERF_ONLINE] = {
+ .name = "perf:online",
+ .startup.single = perf_event_init_cpu,
+ .teardown.single = perf_event_exit_cpu,
+ },
+ [CPUHP_AP_WATCHDOG_ONLINE] = {
+ .name = "lockup_detector:online",
+ .startup.single = lockup_detector_online_cpu,
+ .teardown.single = lockup_detector_offline_cpu,
+ },
+ [CPUHP_AP_WORKQUEUE_ONLINE] = {
+ .name = "workqueue:online",
+ .startup.single = workqueue_online_cpu,
+ .teardown.single = workqueue_offline_cpu,
+ },
+ [CPUHP_AP_RCUTREE_ONLINE] = {
+ .name = "RCU/tree:online",
+ .startup.single = rcutree_online_cpu,
+ .teardown.single = rcutree_offline_cpu,
+ },
+#endif
+ /*
+ * The dynamically registered state space is here
+ */
+
+#ifdef CONFIG_SMP
+ /* Last state is scheduler control setting the cpu active */
+ [CPUHP_AP_ACTIVE] = {
+ .name = "sched:active",
+ .startup.single = sched_cpu_activate,
+ .teardown.single = sched_cpu_deactivate,
+ },
+#endif
+
+ /* CPU is fully up and running. */
+ [CPUHP_ONLINE] = {
+ .name = "online",
+ .startup.single = NULL,
+ .teardown.single = NULL,
+ },
+};
+
+/* Sanity check for callbacks */
+static int cpuhp_cb_check(enum cpuhp_state state)
+{
+ if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE)
+ return -EINVAL;
+ return 0;
+}
+
+/*
+ * Returns a free for dynamic slot assignment of the Online state. The states
+ * are protected by the cpuhp_slot_states mutex and an empty slot is identified
+ * by having no name assigned.
+ */
+static int cpuhp_reserve_state(enum cpuhp_state state)
+{
+ enum cpuhp_state i, end;
+ struct cpuhp_step *step;
+
+ switch (state) {
+ case CPUHP_AP_ONLINE_DYN:
+ step = cpuhp_hp_states + CPUHP_AP_ONLINE_DYN;
+ end = CPUHP_AP_ONLINE_DYN_END;
+ break;
+ case CPUHP_BP_PREPARE_DYN:
+ step = cpuhp_hp_states + CPUHP_BP_PREPARE_DYN;
+ end = CPUHP_BP_PREPARE_DYN_END;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ for (i = state; i <= end; i++, step++) {
+ if (!step->name)
+ return i;
+ }
+ WARN(1, "No more dynamic states available for CPU hotplug\n");
+ return -ENOSPC;
+}
+
+static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name,
+ int (*startup)(unsigned int cpu),
+ int (*teardown)(unsigned int cpu),
+ bool multi_instance)
+{
+ /* (Un)Install the callbacks for further cpu hotplug operations */
+ struct cpuhp_step *sp;
+ int ret = 0;
+
+ /*
+ * If name is NULL, then the state gets removed.
+ *
+ * CPUHP_AP_ONLINE_DYN and CPUHP_BP_PREPARE_DYN are handed out on
+ * the first allocation from these dynamic ranges, so the removal
+ * would trigger a new allocation and clear the wrong (already
+ * empty) state, leaving the callbacks of the to be cleared state
+ * dangling, which causes wreckage on the next hotplug operation.
+ */
+ if (name && (state == CPUHP_AP_ONLINE_DYN ||
+ state == CPUHP_BP_PREPARE_DYN)) {
+ ret = cpuhp_reserve_state(state);
+ if (ret < 0)
+ return ret;
+ state = ret;
+ }
+ sp = cpuhp_get_step(state);
+ if (name && sp->name)
+ return -EBUSY;
+
+ sp->startup.single = startup;
+ sp->teardown.single = teardown;
+ sp->name = name;
+ sp->multi_instance = multi_instance;
+ INIT_HLIST_HEAD(&sp->list);
+ return ret;
+}
+
+static void *cpuhp_get_teardown_cb(enum cpuhp_state state)
+{
+ return cpuhp_get_step(state)->teardown.single;
+}
+
+/*
+ * Call the startup/teardown function for a step either on the AP or
+ * on the current CPU.
+ */
+static int cpuhp_issue_call(int cpu, enum cpuhp_state state, bool bringup,
+ struct hlist_node *node)
+{
+ struct cpuhp_step *sp = cpuhp_get_step(state);
+ int ret;
+
+ /*
+ * If there's nothing to do, we done.
+ * Relies on the union for multi_instance.
+ */
+ if ((bringup && !sp->startup.single) ||
+ (!bringup && !sp->teardown.single))
+ return 0;
+ /*
+ * The non AP bound callbacks can fail on bringup. On teardown
+ * e.g. module removal we crash for now.
+ */
+#ifdef CONFIG_SMP
+ if (cpuhp_is_ap_state(state))
+ ret = cpuhp_invoke_ap_callback(cpu, state, bringup, node);
+ else
+ ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL);
+#else
+ ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL);
+#endif
+ BUG_ON(ret && !bringup);
+ return ret;
+}
+
+/*
+ * Called from __cpuhp_setup_state on a recoverable failure.
+ *
+ * Note: The teardown callbacks for rollback are not allowed to fail!
+ */
+static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
+ struct hlist_node *node)
+{
+ int cpu;
+
+ /* Roll back the already executed steps on the other cpus */
+ for_each_present_cpu(cpu) {
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ int cpustate = st->state;
+
+ if (cpu >= failedcpu)
+ break;
+
+ /* Did we invoke the startup call on that cpu ? */
+ if (cpustate >= state)
+ cpuhp_issue_call(cpu, state, false, node);
+ }
+}
+
+int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state,
+ struct hlist_node *node,
+ bool invoke)
+{
+ struct cpuhp_step *sp;
+ int cpu;
+ int ret;
+
+ lockdep_assert_cpus_held();
+
+ sp = cpuhp_get_step(state);
+ if (sp->multi_instance == false)
+ return -EINVAL;
+
+ mutex_lock(&cpuhp_state_mutex);
+
+ if (!invoke || !sp->startup.multi)
+ goto add_node;
+
+ /*
+ * Try to call the startup callback for each present cpu
+ * depending on the hotplug state of the cpu.
+ */
+ for_each_present_cpu(cpu) {
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ int cpustate = st->state;
+
+ if (cpustate < state)
+ continue;
+
+ ret = cpuhp_issue_call(cpu, state, true, node);
+ if (ret) {
+ if (sp->teardown.multi)
+ cpuhp_rollback_install(cpu, state, node);
+ goto unlock;
+ }
+ }
+add_node:
+ ret = 0;
+ hlist_add_head(node, &sp->list);
+unlock:
+ mutex_unlock(&cpuhp_state_mutex);
+ return ret;
+}
+
+int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
+ bool invoke)
+{
+ int ret;
+
+ cpus_read_lock();
+ ret = __cpuhp_state_add_instance_cpuslocked(state, node, invoke);
+ cpus_read_unlock();
+ return ret;
+}
+EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
+
+/**
+ * __cpuhp_setup_state_cpuslocked - Setup the callbacks for an hotplug machine state
+ * @state: The state to setup
+ * @invoke: If true, the startup function is invoked for cpus where
+ * cpu state >= @state
+ * @startup: startup callback function
+ * @teardown: teardown callback function
+ * @multi_instance: State is set up for multiple instances which get
+ * added afterwards.
+ *
+ * The caller needs to hold cpus read locked while calling this function.
+ * Returns:
+ * On success:
+ * Positive state number if @state is CPUHP_AP_ONLINE_DYN
+ * 0 for all other states
+ * On failure: proper (negative) error code
+ */
+int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state,
+ const char *name, bool invoke,
+ int (*startup)(unsigned int cpu),
+ int (*teardown)(unsigned int cpu),
+ bool multi_instance)
+{
+ int cpu, ret = 0;
+ bool dynstate;
+
+ lockdep_assert_cpus_held();
+
+ if (cpuhp_cb_check(state) || !name)
+ return -EINVAL;
+
+ mutex_lock(&cpuhp_state_mutex);
+
+ ret = cpuhp_store_callbacks(state, name, startup, teardown,
+ multi_instance);
+
+ dynstate = state == CPUHP_AP_ONLINE_DYN;
+ if (ret > 0 && dynstate) {
+ state = ret;
+ ret = 0;
+ }
+
+ if (ret || !invoke || !startup)
+ goto out;
+
+ /*
+ * Try to call the startup callback for each present cpu
+ * depending on the hotplug state of the cpu.
+ */
+ for_each_present_cpu(cpu) {
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ int cpustate = st->state;
+
+ if (cpustate < state)
+ continue;
+
+ ret = cpuhp_issue_call(cpu, state, true, NULL);
+ if (ret) {
+ if (teardown)
+ cpuhp_rollback_install(cpu, state, NULL);
+ cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
+ goto out;
+ }
+ }
+out:
+ mutex_unlock(&cpuhp_state_mutex);
+ /*
+ * If the requested state is CPUHP_AP_ONLINE_DYN, return the
+ * dynamically allocated state in case of success.
+ */
+ if (!ret && dynstate)
+ return state;
+ return ret;
+}
+EXPORT_SYMBOL(__cpuhp_setup_state_cpuslocked);
+
+int __cpuhp_setup_state(enum cpuhp_state state,
+ const char *name, bool invoke,
+ int (*startup)(unsigned int cpu),
+ int (*teardown)(unsigned int cpu),
+ bool multi_instance)
+{
+ int ret;
+
+ cpus_read_lock();
+ ret = __cpuhp_setup_state_cpuslocked(state, name, invoke, startup,
+ teardown, multi_instance);
+ cpus_read_unlock();
+ return ret;
+}
+EXPORT_SYMBOL(__cpuhp_setup_state);
+
+int __cpuhp_state_remove_instance(enum cpuhp_state state,
+ struct hlist_node *node, bool invoke)
+{
+ struct cpuhp_step *sp = cpuhp_get_step(state);
+ int cpu;
+
+ BUG_ON(cpuhp_cb_check(state));
+
+ if (!sp->multi_instance)
+ return -EINVAL;
+
+ cpus_read_lock();
+ mutex_lock(&cpuhp_state_mutex);
+
+ if (!invoke || !cpuhp_get_teardown_cb(state))
+ goto remove;
+ /*
+ * Call the teardown callback for each present cpu depending
+ * on the hotplug state of the cpu. This function is not
+ * allowed to fail currently!
+ */
+ for_each_present_cpu(cpu) {
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ int cpustate = st->state;
+
+ if (cpustate >= state)
+ cpuhp_issue_call(cpu, state, false, node);
+ }
+
+remove:
+ hlist_del(node);
+ mutex_unlock(&cpuhp_state_mutex);
+ cpus_read_unlock();
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance);
+
+/**
+ * __cpuhp_remove_state_cpuslocked - Remove the callbacks for an hotplug machine state
+ * @state: The state to remove
+ * @invoke: If true, the teardown function is invoked for cpus where
+ * cpu state >= @state
+ *
+ * The caller needs to hold cpus read locked while calling this function.
+ * The teardown callback is currently not allowed to fail. Think
+ * about module removal!
+ */
+void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke)
+{
+ struct cpuhp_step *sp = cpuhp_get_step(state);
+ int cpu;
+
+ BUG_ON(cpuhp_cb_check(state));
+
+ lockdep_assert_cpus_held();
+
+ mutex_lock(&cpuhp_state_mutex);
+ if (sp->multi_instance) {
+ WARN(!hlist_empty(&sp->list),
+ "Error: Removing state %d which has instances left.\n",
+ state);
+ goto remove;
+ }
+
+ if (!invoke || !cpuhp_get_teardown_cb(state))
+ goto remove;
+
+ /*
+ * Call the teardown callback for each present cpu depending
+ * on the hotplug state of the cpu. This function is not
+ * allowed to fail currently!
+ */
+ for_each_present_cpu(cpu) {
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ int cpustate = st->state;
+
+ if (cpustate >= state)
+ cpuhp_issue_call(cpu, state, false, NULL);
+ }
+remove:
+ cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
+ mutex_unlock(&cpuhp_state_mutex);
+}
+EXPORT_SYMBOL(__cpuhp_remove_state_cpuslocked);
+
+void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
+{
+ cpus_read_lock();
+ __cpuhp_remove_state_cpuslocked(state, invoke);
+ cpus_read_unlock();
+}
+EXPORT_SYMBOL(__cpuhp_remove_state);
+
+#if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
+static ssize_t show_cpuhp_state(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
+
+ return sprintf(buf, "%d\n", st->state);
+}
+static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);
+
+static ssize_t write_cpuhp_target(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
+ struct cpuhp_step *sp;
+ int target, ret;
+
+ ret = kstrtoint(buf, 10, &target);
+ if (ret)
+ return ret;
+
+#ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL
+ if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE)
+ return -EINVAL;
+#else
+ if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE)
+ return -EINVAL;
+#endif
+
+ ret = lock_device_hotplug_sysfs();
+ if (ret)
+ return ret;
+
+ mutex_lock(&cpuhp_state_mutex);
+ sp = cpuhp_get_step(target);
+ ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
+ mutex_unlock(&cpuhp_state_mutex);
+ if (ret)
+ goto out;
+
+ if (st->state < target)
+ ret = do_cpu_up(dev->id, target);
+ else
+ ret = do_cpu_down(dev->id, target);
+out:
+ unlock_device_hotplug();
+ return ret ? ret : count;
+}
+
+static ssize_t show_cpuhp_target(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
+
+ return sprintf(buf, "%d\n", st->target);
+}
+static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);
+
+
+static ssize_t write_cpuhp_fail(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
+ struct cpuhp_step *sp;
+ int fail, ret;
+
+ ret = kstrtoint(buf, 10, &fail);
+ if (ret)
+ return ret;
+
+ /*
+ * Cannot fail STARTING/DYING callbacks.
+ */
+ if (cpuhp_is_atomic_state(fail))
+ return -EINVAL;
+
+ /*
+ * Cannot fail anything that doesn't have callbacks.
+ */
+ mutex_lock(&cpuhp_state_mutex);
+ sp = cpuhp_get_step(fail);
+ if (!sp->startup.single && !sp->teardown.single)
+ ret = -EINVAL;
+ mutex_unlock(&cpuhp_state_mutex);
+ if (ret)
+ return ret;
+
+ st->fail = fail;
+
+ return count;
+}
+
+static ssize_t show_cpuhp_fail(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
+
+ return sprintf(buf, "%d\n", st->fail);
+}
+
+static DEVICE_ATTR(fail, 0644, show_cpuhp_fail, write_cpuhp_fail);
+
+static struct attribute *cpuhp_cpu_attrs[] = {
+ &dev_attr_state.attr,
+ &dev_attr_target.attr,
+ &dev_attr_fail.attr,
+ NULL
+};
+
+static const struct attribute_group cpuhp_cpu_attr_group = {
+ .attrs = cpuhp_cpu_attrs,
+ .name = "hotplug",
+ NULL
+};
+
+static ssize_t show_cpuhp_states(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ ssize_t cur, res = 0;
+ int i;
+
+ mutex_lock(&cpuhp_state_mutex);
+ for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) {
+ struct cpuhp_step *sp = cpuhp_get_step(i);
+
+ if (sp->name) {
+ cur = sprintf(buf, "%3d: %s\n", i, sp->name);
+ buf += cur;
+ res += cur;
+ }
+ }
+ mutex_unlock(&cpuhp_state_mutex);
+ return res;
+}
+static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL);
+
+static struct attribute *cpuhp_cpu_root_attrs[] = {
+ &dev_attr_states.attr,
+ NULL
+};
+
+static const struct attribute_group cpuhp_cpu_root_attr_group = {
+ .attrs = cpuhp_cpu_root_attrs,
+ .name = "hotplug",
+ NULL
+};
+
+#ifdef 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",
+};
+
+static ssize_t
+show_smt_control(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ return snprintf(buf, PAGE_SIZE - 2, "%s\n", smt_states[cpu_smt_control]);
+}
+
+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, CPUHP_OFFLINE);
+ 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;
+ arch_smt_update();
+ }
+ 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;
+ arch_smt_update();
+ 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, CPUHP_ONLINE);
+ 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;
+}
+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)
+{
+ bool active = topology_max_smt_threads() > 1;
+
+ return snprintf(buf, PAGE_SIZE - 2, "%d\n", 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_state_init(void)
+{
+ return sysfs_create_group(&cpu_subsys.dev_root->kobj,
+ &cpuhp_smt_attr_group);
+}
+
+#else
+static inline int cpu_smt_state_init(void) { return 0; }
+#endif
+
+static int __init cpuhp_sysfs_init(void)
+{
+ int cpu, ret;
+
+ ret = cpu_smt_state_init();
+ if (ret)
+ return ret;
+
+ ret = sysfs_create_group(&cpu_subsys.dev_root->kobj,
+ &cpuhp_cpu_root_attr_group);
+ if (ret)
+ return ret;
+
+ for_each_possible_cpu(cpu) {
+ struct device *dev = get_cpu_device(cpu);
+
+ if (!dev)
+ continue;
+ ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group);
+ if (ret)
+ return ret;
+ }
+ return 0;
+}
+device_initcall(cpuhp_sysfs_init);
+#endif
+
+/*
+ * cpu_bit_bitmap[] is a special, "compressed" data structure that
+ * represents all NR_CPUS bits binary values of 1<<nr.
+ *
+ * It is used by cpumask_of() to get a constant address to a CPU
+ * mask value that has a single bit set only.
+ */
+
+/* cpu_bit_bitmap[0] is empty - so we can back into it */
+#define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
+#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
+#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
+#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
+
+const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
+
+ MASK_DECLARE_8(0), MASK_DECLARE_8(8),
+ MASK_DECLARE_8(16), MASK_DECLARE_8(24),
+#if BITS_PER_LONG > 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
+struct cpumask __cpu_possible_mask __read_mostly
+ = {CPU_BITS_ALL};
+#else
+struct cpumask __cpu_possible_mask __read_mostly;
+#endif
+EXPORT_SYMBOL(__cpu_possible_mask);
+
+struct cpumask __cpu_online_mask __read_mostly;
+EXPORT_SYMBOL(__cpu_online_mask);
+
+struct cpumask __cpu_present_mask __read_mostly;
+EXPORT_SYMBOL(__cpu_present_mask);
+
+struct cpumask __cpu_active_mask __read_mostly;
+EXPORT_SYMBOL(__cpu_active_mask);
+
+void init_cpu_present(const struct cpumask *src)
+{
+ cpumask_copy(&__cpu_present_mask, src);
+}
+
+void init_cpu_possible(const struct cpumask *src)
+{
+ cpumask_copy(&__cpu_possible_mask, src);
+}
+
+void init_cpu_online(const struct cpumask *src)
+{
+ cpumask_copy(&__cpu_online_mask, src);
+}
+
+/*
+ * Activate the first processor.
+ */
+void __init boot_cpu_init(void)
+{
+ int cpu = smp_processor_id();
+
+ /* Mark the boot cpu "present", "online" etc for SMP and UP case */
+ set_cpu_online(cpu, true);
+ set_cpu_active(cpu, true);
+ set_cpu_present(cpu, true);
+ set_cpu_possible(cpu, true);
+
+#ifdef CONFIG_SMP
+ __boot_cpu_id = cpu;
+#endif
+}
+
+/*
+ * Must be called _AFTER_ setting up the per_cpu areas
+ */
+void __init boot_cpu_hotplug_init(void)
+{
+#ifdef CONFIG_SMP
+ this_cpu_write(cpuhp_state.booted_once, true);
+#endif
+ this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);
+}