kernel/cpu.c

   1 /* CPU control.
   2  * (C) 2001, 2002, 2003, 2004 Rusty Russell
   3  *
   4  * This code is licenced under the GPL.
   5  */
   6 #include <linux/proc_fs.h>
   7 #include <linux/smp.h>
   8 #include <linux/init.h>
   9 #include <linux/notifier.h>
  10 #include <linux/sched.h>
  11 #include <linux/unistd.h>
  12 #include <linux/cpu.h>
  13 #include <linux/oom.h>
  14 #include <linux/rcupdate.h>
  15 #include <linux/export.h>
  16 #include <linux/bug.h>
  17 #include <linux/kthread.h>
  18 #include <linux/stop_machine.h>
  19 #include <linux/mutex.h>
  20 #include <linux/gfp.h>
  21 #include <linux/suspend.h>
  22 #include <linux/lockdep.h>
  23 #include <linux/tick.h>
  24 #include <linux/irq.h>
  25
  26 #include <trace/events/power.h>
  27 #define CREATE_TRACE_POINTS
  28 #include <trace/events/cpuhp.h>
  29
  30 #include "smpboot.h"
  31
  32 /**
  33  * cpuhp_cpu_state - Per cpu hotplug state storage
  34  * @state:      The current cpu state
  35  * @target:     The target state
  36  */
  37 struct cpuhp_cpu_state {
  38         enum cpuhp_state        state;
  39         enum cpuhp_state        target;
  40 };
  41
  42 static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state);
  43
  44 /**
  45  * cpuhp_step - Hotplug state machine step
  46  * @name:       Name of the step
  47  * @startup:    Startup function of the step
  48  * @teardown:   Teardown function of the step
  49  * @skip_onerr: Do not invoke the functions on error rollback
  50  *              Will go away once the notifiers are gone
  51  * @cant_stop:  Bringup/teardown can't be stopped at this step
  52  */
  53 struct cpuhp_step {
  54         const char      *name;
  55         int             (*startup)(unsigned int cpu);
  56         int             (*teardown)(unsigned int cpu);
  57         bool            skip_onerr;
  58         bool            cant_stop;
  59 };
  60
  61 static DEFINE_MUTEX(cpuhp_state_mutex);
  62 static struct cpuhp_step cpuhp_bp_states[];
  63 static struct cpuhp_step cpuhp_ap_states[];
  64
  65 /**
  66  * cpuhp_invoke_callback _ Invoke the callbacks for a given state
  67  * @cpu:        The cpu for which the callback should be invoked
  68  * @step:       The step in the state machine
  69  * @cb:         The callback function to invoke
  70  *
  71  * Called from cpu hotplug and from the state register machinery
  72  */
  73 static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state step,
  74                                  int (*cb)(unsigned int))
  75 {
  76         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
  77         int ret = 0;
  78
  79         if (cb) {
  80                 trace_cpuhp_enter(cpu, st->target, step, cb);
  81                 ret = cb(cpu);
  82                 trace_cpuhp_exit(cpu, st->state, step, ret);
  83         }
  84         return ret;
  85 }
  86
  87 #ifdef CONFIG_SMP
  88 /* Serializes the updates to cpu_online_mask, cpu_present_mask */
  89 static DEFINE_MUTEX(cpu_add_remove_lock);
  90 bool cpuhp_tasks_frozen;
  91 EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen);
  92
  93 /*
  94  * The following two APIs (cpu_maps_update_begin/done) must be used when
  95  * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
  96  * The APIs cpu_notifier_register_begin/done() must be used to protect CPU
  97  * hotplug callback (un)registration performed using __register_cpu_notifier()
  98  * or __unregister_cpu_notifier().
  99  */
 100 void cpu_maps_update_begin(void)
 101 {
 102         mutex_lock(&cpu_add_remove_lock);
 103 }
 104 EXPORT_SYMBOL(cpu_notifier_register_begin);
 105
 106 void cpu_maps_update_done(void)
 107 {
 108         mutex_unlock(&cpu_add_remove_lock);
 109 }
 110 EXPORT_SYMBOL(cpu_notifier_register_done);
 111
 112 static RAW_NOTIFIER_HEAD(cpu_chain);
 113
 114 /* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
 115  * Should always be manipulated under cpu_add_remove_lock
 116  */
 117 static int cpu_hotplug_disabled;
 118
 119 #ifdef CONFIG_HOTPLUG_CPU
 120
 121 static struct {
 122         struct task_struct *active_writer;
 123         /* wait queue to wake up the active_writer */
 124         wait_queue_head_t wq;
 125         /* verifies that no writer will get active while readers are active */
 126         struct mutex lock;
 127         /*
 128          * Also blocks the new readers during
 129          * an ongoing cpu hotplug operation.
 130          */
 131         atomic_t refcount;
 132
 133 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 134         struct lockdep_map dep_map;
 135 #endif
 136 } cpu_hotplug = {
 137         .active_writer = NULL,
 138         .wq = __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug.wq),
 139         .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
 140 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 141         .dep_map = {.name = "cpu_hotplug.lock" },
 142 #endif
 143 };
 144
 145 /* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */
 146 #define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map)
 147 #define cpuhp_lock_acquire_tryread() \
 148                                   lock_map_acquire_tryread(&cpu_hotplug.dep_map)
 149 #define cpuhp_lock_acquire()      lock_map_acquire(&cpu_hotplug.dep_map)
 150 #define cpuhp_lock_release()      lock_map_release(&cpu_hotplug.dep_map)
 151
 152
 153 void get_online_cpus(void)
 154 {
 155         might_sleep();
 156         if (cpu_hotplug.active_writer == current)
 157                 return;
 158         cpuhp_lock_acquire_read();
 159         mutex_lock(&cpu_hotplug.lock);
 160         atomic_inc(&cpu_hotplug.refcount);
 161         mutex_unlock(&cpu_hotplug.lock);
 162 }
 163 EXPORT_SYMBOL_GPL(get_online_cpus);
 164
 165 void put_online_cpus(void)
 166 {
 167         int refcount;
 168
 169         if (cpu_hotplug.active_writer == current)
 170                 return;
 171
 172         refcount = atomic_dec_return(&cpu_hotplug.refcount);
 173         if (WARN_ON(refcount < 0)) /* try to fix things up */
 174                 atomic_inc(&cpu_hotplug.refcount);
 175
 176         if (refcount <= 0 && waitqueue_active(&cpu_hotplug.wq))
 177                 wake_up(&cpu_hotplug.wq);
 178
 179         cpuhp_lock_release();
 180
 181 }
 182 EXPORT_SYMBOL_GPL(put_online_cpus);
 183
 184 /*
 185  * This ensures that the hotplug operation can begin only when the
 186  * refcount goes to zero.
 187  *
 188  * Note that during a cpu-hotplug operation, the new readers, if any,
 189  * will be blocked by the cpu_hotplug.lock
 190  *
 191  * Since cpu_hotplug_begin() is always called after invoking
 192  * cpu_maps_update_begin(), we can be sure that only one writer is active.
 193  *
 194  * Note that theoretically, there is a possibility of a livelock:
 195  * - Refcount goes to zero, last reader wakes up the sleeping
 196  *   writer.
 197  * - Last reader unlocks the cpu_hotplug.lock.
 198  * - A new reader arrives at this moment, bumps up the refcount.
 199  * - The writer acquires the cpu_hotplug.lock finds the refcount
 200  *   non zero and goes to sleep again.
 201  *
 202  * However, this is very difficult to achieve in practice since
 203  * get_online_cpus() not an api which is called all that often.
 204  *
 205  */
 206 void cpu_hotplug_begin(void)
 207 {
 208         DEFINE_WAIT(wait);
 209
 210         cpu_hotplug.active_writer = current;
 211         cpuhp_lock_acquire();
 212
 213         for (;;) {
 214                 mutex_lock(&cpu_hotplug.lock);
 215                 prepare_to_wait(&cpu_hotplug.wq, &wait, TASK_UNINTERRUPTIBLE);
 216                 if (likely(!atomic_read(&cpu_hotplug.refcount)))
 217                                 break;
 218                 mutex_unlock(&cpu_hotplug.lock);
 219                 schedule();
 220         }
 221         finish_wait(&cpu_hotplug.wq, &wait);
 222 }
 223
 224 void cpu_hotplug_done(void)
 225 {
 226         cpu_hotplug.active_writer = NULL;
 227         mutex_unlock(&cpu_hotplug.lock);
 228         cpuhp_lock_release();
 229 }
 230
 231 /*
 232  * Wait for currently running CPU hotplug operations to complete (if any) and
 233  * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
 234  * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
 235  * hotplug path before performing hotplug operations. So acquiring that lock
 236  * guarantees mutual exclusion from any currently running hotplug operations.
 237  */
 238 void cpu_hotplug_disable(void)
 239 {
 240         cpu_maps_update_begin();
 241         cpu_hotplug_disabled++;
 242         cpu_maps_update_done();
 243 }
 244 EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
 245
 246 void cpu_hotplug_enable(void)
 247 {
 248         cpu_maps_update_begin();
 249         WARN_ON(--cpu_hotplug_disabled < 0);
 250         cpu_maps_update_done();
 251 }
 252 EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
 253 #endif  /* CONFIG_HOTPLUG_CPU */
 254
 255 /* Need to know about CPUs going up/down? */
 256 int register_cpu_notifier(struct notifier_block *nb)
 257 {
 258         int ret;
 259         cpu_maps_update_begin();
 260         ret = raw_notifier_chain_register(&cpu_chain, nb);
 261         cpu_maps_update_done();
 262         return ret;
 263 }
 264
 265 int __register_cpu_notifier(struct notifier_block *nb)
 266 {
 267         return raw_notifier_chain_register(&cpu_chain, nb);
 268 }
 269
 270 static int __cpu_notify(unsigned long val, unsigned int cpu, int nr_to_call,
 271                         int *nr_calls)
 272 {
 273         unsigned long mod = cpuhp_tasks_frozen ? CPU_TASKS_FROZEN : 0;
 274         void *hcpu = (void *)(long)cpu;
 275
 276         int ret;
 277
 278         ret = __raw_notifier_call_chain(&cpu_chain, val | mod, hcpu, nr_to_call,
 279                                         nr_calls);
 280
 281         return notifier_to_errno(ret);
 282 }
 283
 284 static int cpu_notify(unsigned long val, unsigned int cpu)
 285 {
 286         return __cpu_notify(val, cpu, -1, NULL);
 287 }
 288
 289 /* Notifier wrappers for transitioning to state machine */
 290 static int notify_prepare(unsigned int cpu)
 291 {
 292         int nr_calls = 0;
 293         int ret;
 294
 295         ret = __cpu_notify(CPU_UP_PREPARE, cpu, -1, &nr_calls);
 296         if (ret) {
 297                 nr_calls--;
 298                 printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
 299                                 __func__, cpu);
 300                 __cpu_notify(CPU_UP_CANCELED, cpu, nr_calls, NULL);
 301         }
 302         return ret;
 303 }
 304
 305 static int notify_online(unsigned int cpu)
 306 {
 307         cpu_notify(CPU_ONLINE, cpu);
 308         return 0;
 309 }
 310
 311 static int notify_starting(unsigned int cpu)
 312 {
 313         cpu_notify(CPU_STARTING, cpu);
 314         return 0;
 315 }
 316
 317 static int bringup_cpu(unsigned int cpu)
 318 {
 319         struct task_struct *idle = idle_thread_get(cpu);
 320         int ret;
 321
 322         /* Arch-specific enabling code. */
 323         ret = __cpu_up(cpu, idle);
 324         if (ret) {
 325                 cpu_notify(CPU_UP_CANCELED, cpu);
 326                 return ret;
 327         }
 328         BUG_ON(!cpu_online(cpu));
 329         return 0;
 330 }
 331
 332 #ifdef CONFIG_HOTPLUG_CPU
 333 EXPORT_SYMBOL(register_cpu_notifier);
 334 EXPORT_SYMBOL(__register_cpu_notifier);
 335
 336 void unregister_cpu_notifier(struct notifier_block *nb)
 337 {
 338         cpu_maps_update_begin();
 339         raw_notifier_chain_unregister(&cpu_chain, nb);
 340         cpu_maps_update_done();
 341 }
 342 EXPORT_SYMBOL(unregister_cpu_notifier);
 343
 344 void __unregister_cpu_notifier(struct notifier_block *nb)
 345 {
 346         raw_notifier_chain_unregister(&cpu_chain, nb);
 347 }
 348 EXPORT_SYMBOL(__unregister_cpu_notifier);
 349
 350 /**
 351  * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
 352  * @cpu: a CPU id
 353  *
 354  * This function walks all processes, finds a valid mm struct for each one and
 355  * then clears a corresponding bit in mm's cpumask.  While this all sounds
 356  * trivial, there are various non-obvious corner cases, which this function
 357  * tries to solve in a safe manner.
 358  *
 359  * Also note that the function uses a somewhat relaxed locking scheme, so it may
 360  * be called only for an already offlined CPU.
 361  */
 362 void clear_tasks_mm_cpumask(int cpu)
 363 {
 364         struct task_struct *p;
 365
 366         /*
 367          * This function is called after the cpu is taken down and marked
 368          * offline, so its not like new tasks will ever get this cpu set in
 369          * their mm mask. -- Peter Zijlstra
 370          * Thus, we may use rcu_read_lock() here, instead of grabbing
 371          * full-fledged tasklist_lock.
 372          */
 373         WARN_ON(cpu_online(cpu));
 374         rcu_read_lock();
 375         for_each_process(p) {
 376                 struct task_struct *t;
 377
 378                 /*
 379                  * Main thread might exit, but other threads may still have
 380                  * a valid mm. Find one.
 381                  */
 382                 t = find_lock_task_mm(p);
 383                 if (!t)
 384                         continue;
 385                 cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
 386                 task_unlock(t);
 387         }
 388         rcu_read_unlock();
 389 }
 390
 391 static inline void check_for_tasks(int dead_cpu)
 392 {
 393         struct task_struct *g, *p;
 394
 395         read_lock(&tasklist_lock);
 396         for_each_process_thread(g, p) {
 397                 if (!p->on_rq)
 398                         continue;
 399                 /*
 400                  * We do the check with unlocked task_rq(p)->lock.
 401                  * Order the reading to do not warn about a task,
 402                  * which was running on this cpu in the past, and
 403                  * it's just been woken on another cpu.
 404                  */
 405                 rmb();
 406                 if (task_cpu(p) != dead_cpu)
 407                         continue;
 408
 409                 pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
 410                         p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags);
 411         }
 412         read_unlock(&tasklist_lock);
 413 }
 414
 415 static void cpu_notify_nofail(unsigned long val, unsigned int cpu)
 416 {
 417         BUG_ON(cpu_notify(val, cpu));
 418 }
 419
 420 static int notify_down_prepare(unsigned int cpu)
 421 {
 422         int err, nr_calls = 0;
 423
 424         err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls);
 425         if (err) {
 426                 nr_calls--;
 427                 __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL);
 428                 pr_warn("%s: attempt to take down CPU %u failed\n",
 429                                 __func__, cpu);
 430         }
 431         return err;
 432 }
 433
 434 static int notify_dying(unsigned int cpu)
 435 {
 436         cpu_notify(CPU_DYING, cpu);
 437         return 0;
 438 }
 439
 440 /* Take this CPU down. */
 441 static int take_cpu_down(void *_param)
 442 {
 443         struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
 444         enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE);
 445         int err, cpu = smp_processor_id();
 446
 447         /* Ensure this CPU doesn't handle any more interrupts. */
 448         err = __cpu_disable();
 449         if (err < 0)
 450                 return err;
 451
 452         /* Invoke the former CPU_DYING callbacks */
 453         for (; st->state > target; st->state--) {
 454                 struct cpuhp_step *step = cpuhp_ap_states + st->state;
 455
 456                 cpuhp_invoke_callback(cpu, st->state, step->teardown);
 457         }
 458         /* Give up timekeeping duties */
 459         tick_handover_do_timer();
 460         /* Park the stopper thread */
 461         stop_machine_park(cpu);
 462         return 0;
 463 }
 464
 465 static int takedown_cpu(unsigned int cpu)
 466 {
 467         int err;
 468
 469         /*
 470          * By now we've cleared cpu_active_mask, wait for all preempt-disabled
 471          * and RCU users of this state to go away such that all new such users
 472          * will observe it.
 473          *
 474          * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might
 475          * not imply sync_sched(), so wait for both.
 476          *
 477          * Do sync before park smpboot threads to take care the rcu boost case.
 478          */
 479         if (IS_ENABLED(CONFIG_PREEMPT))
 480                 synchronize_rcu_mult(call_rcu, call_rcu_sched);
 481         else
 482                 synchronize_rcu();
 483
 484         /*
 485          * Prevent irq alloc/free while the dying cpu reorganizes the
 486          * interrupt affinities.
 487          */
 488         irq_lock_sparse();
 489
 490         /*
 491          * So now all preempt/rcu users must observe !cpu_active().
 492          */
 493         err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu));
 494         if (err) {
 495                 /* CPU didn't die: tell everyone.  Can't complain. */
 496                 cpu_notify_nofail(CPU_DOWN_FAILED, cpu);
 497                 irq_unlock_sparse();
 498                 return err;
 499         }
 500         BUG_ON(cpu_online(cpu));
 501
 502         /*
 503          * The migration_call() CPU_DYING callback will have removed all
 504          * runnable tasks from the cpu, there's only the idle task left now
 505          * that the migration thread is done doing the stop_machine thing.
 506          *
 507          * Wait for the stop thread to go away.
 508          */
 509         while (!per_cpu(cpu_dead_idle, cpu))
 510                 cpu_relax();
 511         smp_mb(); /* Read from cpu_dead_idle before __cpu_die(). */
 512         per_cpu(cpu_dead_idle, cpu) = false;
 513
 514         /* Interrupts are moved away from the dying cpu, reenable alloc/free */
 515         irq_unlock_sparse();
 516
 517         hotplug_cpu__broadcast_tick_pull(cpu);
 518         /* This actually kills the CPU. */
 519         __cpu_die(cpu);
 520
 521         tick_cleanup_dead_cpu(cpu);
 522         return 0;
 523 }
 524
 525 static int notify_dead(unsigned int cpu)
 526 {
 527         cpu_notify_nofail(CPU_DEAD, cpu);
 528         check_for_tasks(cpu);
 529         return 0;
 530 }
 531
 532 #else
 533 #define notify_down_prepare     NULL
 534 #define takedown_cpu            NULL
 535 #define notify_dead             NULL
 536 #define notify_dying            NULL
 537 #endif
 538
 539 #ifdef CONFIG_HOTPLUG_CPU
 540 static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st)
 541 {
 542         for (st->state++; st->state < st->target; st->state++) {
 543                 struct cpuhp_step *step = cpuhp_bp_states + st->state;
 544
 545                 if (!step->skip_onerr)
 546                         cpuhp_invoke_callback(cpu, st->state, step->startup);
 547         }
 548 }
 549
 550 /* Requires cpu_add_remove_lock to be held */
 551 static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
 552                            enum cpuhp_state target)
 553 {
 554         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
 555         int prev_state, ret = 0;
 556         bool hasdied = false;
 557
 558         if (num_online_cpus() == 1)
 559                 return -EBUSY;
 560
 561         if (!cpu_present(cpu))
 562                 return -EINVAL;
 563
 564         cpu_hotplug_begin();
 565
 566         cpuhp_tasks_frozen = tasks_frozen;
 567
 568         prev_state = st->state;
 569         st->target = target;
 570         for (; st->state > st->target; st->state--) {
 571                 struct cpuhp_step *step = cpuhp_bp_states + st->state;
 572
 573                 ret = cpuhp_invoke_callback(cpu, st->state, step->teardown);
 574                 if (ret) {
 575                         st->target = prev_state;
 576                         undo_cpu_down(cpu, st);
 577                         break;
 578                 }
 579         }
 580         hasdied = prev_state != st->state && st->state == CPUHP_OFFLINE;
 581
 582         cpu_hotplug_done();
 583         /* This post dead nonsense must die */
 584         if (!ret && hasdied)
 585                 cpu_notify_nofail(CPU_POST_DEAD, cpu);
 586         return ret;
 587 }
 588
 589 static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
 590 {
 591         int err;
 592
 593         cpu_maps_update_begin();
 594
 595         if (cpu_hotplug_disabled) {
 596                 err = -EBUSY;
 597                 goto out;
 598         }
 599
 600         err = _cpu_down(cpu, 0, target);
 601
 602 out:
 603         cpu_maps_update_done();
 604         return err;
 605 }
 606 int cpu_down(unsigned int cpu)
 607 {
 608         return do_cpu_down(cpu, CPUHP_OFFLINE);
 609 }
 610 EXPORT_SYMBOL(cpu_down);
 611 #endif /*CONFIG_HOTPLUG_CPU*/
 612
 613 /**
 614  * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
 615  * @cpu: cpu that just started
 616  *
 617  * This function calls the cpu_chain notifiers with CPU_STARTING.
 618  * It must be called by the arch code on the new cpu, before the new cpu
 619  * enables interrupts and before the "boot" cpu returns from __cpu_up().
 620  */
 621 void notify_cpu_starting(unsigned int cpu)
 622 {
 623         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
 624         enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
 625
 626         while (st->state < target) {
 627                 struct cpuhp_step *step;
 628
 629                 st->state++;
 630                 step = cpuhp_ap_states + st->state;
 631                 cpuhp_invoke_callback(cpu, st->state, step->startup);
 632         }
 633 }
 634
 635 /*
 636  * Called from the idle task. We need to set active here, so we can kick off
 637  * the stopper thread.
 638  */
 639 static int cpuhp_set_cpu_active(unsigned int cpu)
 640 {
 641         /* The cpu is marked online, set it active now */
 642         set_cpu_active(cpu, true);
 643         /* Unpark the stopper thread */
 644         stop_machine_unpark(cpu);
 645         return 0;
 646 }
 647
 648 static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st)
 649 {
 650         for (st->state--; st->state > st->target; st->state--) {
 651                 struct cpuhp_step *step = cpuhp_bp_states + st->state;
 652
 653                 if (!step->skip_onerr)
 654                         cpuhp_invoke_callback(cpu, st->state, step->teardown);
 655         }
 656 }
 657
 658 /* Requires cpu_add_remove_lock to be held */
 659 static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
 660 {
 661         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
 662         struct task_struct *idle;
 663         int prev_state, ret = 0;
 664
 665         cpu_hotplug_begin();
 666
 667         if (!cpu_present(cpu)) {
 668                 ret = -EINVAL;
 669                 goto out;
 670         }
 671
 672         /*
 673          * The caller of do_cpu_up might have raced with another
 674          * caller. Ignore it for now.
 675          */
 676         if (st->state >= target)
 677                 goto out;
 678
 679         if (st->state == CPUHP_OFFLINE) {
 680                 /* Let it fail before we try to bring the cpu up */
 681                 idle = idle_thread_get(cpu);
 682                 if (IS_ERR(idle)) {
 683                         ret = PTR_ERR(idle);
 684                         goto out;
 685                 }
 686         }
 687
 688         cpuhp_tasks_frozen = tasks_frozen;
 689
 690         prev_state = st->state;
 691         st->target = target;
 692         while (st->state < st->target) {
 693                 struct cpuhp_step *step;
 694
 695                 st->state++;
 696                 step = cpuhp_bp_states + st->state;
 697                 ret = cpuhp_invoke_callback(cpu, st->state, step->startup);
 698                 if (ret) {
 699                         st->target = prev_state;
 700                         undo_cpu_up(cpu, st);
 701                         break;
 702                 }
 703         }
 704 out:
 705         cpu_hotplug_done();
 706         return ret;
 707 }
 708
 709 static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
 710 {
 711         int err = 0;
 712
 713         if (!cpu_possible(cpu)) {
 714                 pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
 715                        cpu);
 716 #if defined(CONFIG_IA64)
 717                 pr_err("please check additional_cpus= boot parameter\n");
 718 #endif
 719                 return -EINVAL;
 720         }
 721
 722         err = try_online_node(cpu_to_node(cpu));
 723         if (err)
 724                 return err;
 725
 726         cpu_maps_update_begin();
 727
 728         if (cpu_hotplug_disabled) {
 729                 err = -EBUSY;
 730                 goto out;
 731         }
 732
 733         err = _cpu_up(cpu, 0, target);
 734 out:
 735         cpu_maps_update_done();
 736         return err;
 737 }
 738
 739 int cpu_up(unsigned int cpu)
 740 {
 741         return do_cpu_up(cpu, CPUHP_ONLINE);
 742 }
 743 EXPORT_SYMBOL_GPL(cpu_up);
 744
 745 #ifdef CONFIG_PM_SLEEP_SMP
 746 static cpumask_var_t frozen_cpus;
 747
 748 int disable_nonboot_cpus(void)
 749 {
 750         int cpu, first_cpu, error = 0;
 751
 752         cpu_maps_update_begin();
 753         first_cpu = cpumask_first(cpu_online_mask);
 754         /*
 755          * We take down all of the non-boot CPUs in one shot to avoid races
 756          * with the userspace trying to use the CPU hotplug at the same time
 757          */
 758         cpumask_clear(frozen_cpus);
 759
 760         pr_info("Disabling non-boot CPUs ...\n");
 761         for_each_online_cpu(cpu) {
 762                 if (cpu == first_cpu)
 763                         continue;
 764                 trace_suspend_resume(TPS("CPU_OFF"), cpu, true);
 765                 error = _cpu_down(cpu, 1, CPUHP_OFFLINE);
 766                 trace_suspend_resume(TPS("CPU_OFF"), cpu, false);
 767                 if (!error)
 768                         cpumask_set_cpu(cpu, frozen_cpus);
 769                 else {
 770                         pr_err("Error taking CPU%d down: %d\n", cpu, error);
 771                         break;
 772                 }
 773         }
 774
 775         if (!error)
 776                 BUG_ON(num_online_cpus() > 1);
 777         else
 778                 pr_err("Non-boot CPUs are not disabled\n");
 779
 780         /*
 781          * Make sure the CPUs won't be enabled by someone else. We need to do
 782          * this even in case of failure as all disable_nonboot_cpus() users are
 783          * supposed to do enable_nonboot_cpus() on the failure path.
 784          */
 785         cpu_hotplug_disabled++;
 786
 787         cpu_maps_update_done();
 788         return error;
 789 }
 790
 791 void __weak arch_enable_nonboot_cpus_begin(void)
 792 {
 793 }
 794
 795 void __weak arch_enable_nonboot_cpus_end(void)
 796 {
 797 }
 798
 799 void enable_nonboot_cpus(void)
 800 {
 801         int cpu, error;
 802
 803         /* Allow everyone to use the CPU hotplug again */
 804         cpu_maps_update_begin();
 805         WARN_ON(--cpu_hotplug_disabled < 0);
 806         if (cpumask_empty(frozen_cpus))
 807                 goto out;
 808
 809         pr_info("Enabling non-boot CPUs ...\n");
 810
 811         arch_enable_nonboot_cpus_begin();
 812
 813         for_each_cpu(cpu, frozen_cpus) {
 814                 trace_suspend_resume(TPS("CPU_ON"), cpu, true);
 815                 error = _cpu_up(cpu, 1, CPUHP_ONLINE);
 816                 trace_suspend_resume(TPS("CPU_ON"), cpu, false);
 817                 if (!error) {
 818                         pr_info("CPU%d is up\n", cpu);
 819                         continue;
 820                 }
 821                 pr_warn("Error taking CPU%d up: %d\n", cpu, error);
 822         }
 823
 824         arch_enable_nonboot_cpus_end();
 825
 826         cpumask_clear(frozen_cpus);
 827 out:
 828         cpu_maps_update_done();
 829 }
 830
 831 static int __init alloc_frozen_cpus(void)
 832 {
 833         if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
 834                 return -ENOMEM;
 835         return 0;
 836 }
 837 core_initcall(alloc_frozen_cpus);
 838
 839 /*
 840  * When callbacks for CPU hotplug notifications are being executed, we must
 841  * ensure that the state of the system with respect to the tasks being frozen
 842  * or not, as reported by the notification, remains unchanged *throughout the
 843  * duration* of the execution of the callbacks.
 844  * Hence we need to prevent the freezer from racing with regular CPU hotplug.
 845  *
 846  * This synchronization is implemented by mutually excluding regular CPU
 847  * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
 848  * Hibernate notifications.
 849  */
 850 static int
 851 cpu_hotplug_pm_callback(struct notifier_block *nb,
 852                         unsigned long action, void *ptr)
 853 {
 854         switch (action) {
 855
 856         case PM_SUSPEND_PREPARE:
 857         case PM_HIBERNATION_PREPARE:
 858                 cpu_hotplug_disable();
 859                 break;
 860
 861         case PM_POST_SUSPEND:
 862         case PM_POST_HIBERNATION:
 863                 cpu_hotplug_enable();
 864                 break;
 865
 866         default:
 867                 return NOTIFY_DONE;
 868         }
 869
 870         return NOTIFY_OK;
 871 }
 872
 873
 874 static int __init cpu_hotplug_pm_sync_init(void)
 875 {
 876         /*
 877          * cpu_hotplug_pm_callback has higher priority than x86
 878          * bsp_pm_callback which depends on cpu_hotplug_pm_callback
 879          * to disable cpu hotplug to avoid cpu hotplug race.
 880          */
 881         pm_notifier(cpu_hotplug_pm_callback, 0);
 882         return 0;
 883 }
 884 core_initcall(cpu_hotplug_pm_sync_init);
 885
 886 #endif /* CONFIG_PM_SLEEP_SMP */
 887
 888 #endif /* CONFIG_SMP */
 889
 890 /* Boot processor state steps */
 891 static struct cpuhp_step cpuhp_bp_states[] = {
 892         [CPUHP_OFFLINE] = {
 893                 .name                   = "offline",
 894                 .startup                = NULL,
 895                 .teardown               = NULL,
 896         },
 897 #ifdef CONFIG_SMP
 898         [CPUHP_CREATE_THREADS]= {
 899                 .name                   = "threads:create",
 900                 .startup                = smpboot_create_threads,
 901                 .teardown               = NULL,
 902                 .cant_stop              = true,
 903         },
 904         [CPUHP_NOTIFY_PREPARE] = {
 905                 .name                   = "notify:prepare",
 906                 .startup                = notify_prepare,
 907                 .teardown               = notify_dead,
 908                 .skip_onerr             = true,
 909                 .cant_stop              = true,
 910         },
 911         [CPUHP_BRINGUP_CPU] = {
 912                 .name                   = "cpu:bringup",
 913                 .startup                = bringup_cpu,
 914                 .teardown               = NULL,
 915                 .cant_stop              = true,
 916         },
 917         [CPUHP_TEARDOWN_CPU] = {
 918                 .name                   = "cpu:teardown",
 919                 .startup                = NULL,
 920                 .teardown               = takedown_cpu,
 921                 .cant_stop              = true,
 922         },
 923         [CPUHP_CPU_SET_ACTIVE] = {
 924                 .name                   = "cpu:active",
 925                 .startup                = cpuhp_set_cpu_active,
 926                 .teardown               = NULL,
 927         },
 928         [CPUHP_SMPBOOT_THREADS] = {
 929                 .name                   = "smpboot:threads",
 930                 .startup                = smpboot_unpark_threads,
 931                 .teardown               = smpboot_park_threads,
 932         },
 933         [CPUHP_NOTIFY_ONLINE] = {
 934                 .name                   = "notify:online",
 935                 .startup                = notify_online,
 936                 .teardown               = notify_down_prepare,
 937                 .cant_stop              = true,
 938         },
 939 #endif
 940         [CPUHP_ONLINE] = {
 941                 .name                   = "online",
 942                 .startup                = NULL,
 943                 .teardown               = NULL,
 944         },
 945 };
 946
 947 /* Application processor state steps */
 948 static struct cpuhp_step cpuhp_ap_states[] = {
 949 #ifdef CONFIG_SMP
 950         [CPUHP_AP_NOTIFY_STARTING] = {
 951                 .name                   = "notify:starting",
 952                 .startup                = notify_starting,
 953                 .teardown               = notify_dying,
 954                 .skip_onerr             = true,
 955                 .cant_stop              = true,
 956         },
 957 #endif
 958         [CPUHP_ONLINE] = {
 959                 .name                   = "online",
 960                 .startup                = NULL,
 961                 .teardown               = NULL,
 962         },
 963 };
 964
 965 /* Sanity check for callbacks */
 966 static int cpuhp_cb_check(enum cpuhp_state state)
 967 {
 968         if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE)
 969                 return -EINVAL;
 970         return 0;
 971 }
 972
 973 static bool cpuhp_is_ap_state(enum cpuhp_state state)
 974 {
 975         return (state > CPUHP_AP_OFFLINE && state < CPUHP_AP_ONLINE);
 976 }
 977
 978 static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
 979 {
 980         struct cpuhp_step *sp;
 981
 982         sp = cpuhp_is_ap_state(state) ? cpuhp_ap_states : cpuhp_bp_states;
 983         return sp + state;
 984 }
 985
 986 static void cpuhp_store_callbacks(enum cpuhp_state state,
 987                                   const char *name,
 988                                   int (*startup)(unsigned int cpu),
 989                                   int (*teardown)(unsigned int cpu))
 990 {
 991         /* (Un)Install the callbacks for further cpu hotplug operations */
 992         struct cpuhp_step *sp;
 993
 994         mutex_lock(&cpuhp_state_mutex);
 995         sp = cpuhp_get_step(state);
 996         sp->startup = startup;
 997         sp->teardown = teardown;
 998         sp->name = name;
 999         mutex_unlock(&cpuhp_state_mutex);
1000 }
1001
1002 static void *cpuhp_get_teardown_cb(enum cpuhp_state state)
1003 {
1004         return cpuhp_get_step(state)->teardown;
1005 }
1006
1007 /* Helper function to run callback on the target cpu */
1008 static void cpuhp_on_cpu_cb(void *__cb)
1009 {
1010         int (*cb)(unsigned int cpu) = __cb;
1011
1012         BUG_ON(cb(smp_processor_id()));
1013 }
1014
1015 /*
1016  * Call the startup/teardown function for a step either on the AP or
1017  * on the current CPU.
1018  */
1019 static int cpuhp_issue_call(int cpu, enum cpuhp_state state,
1020                             int (*cb)(unsigned int), bool bringup)
1021 {
1022         int ret;
1023
1024         if (!cb)
1025                 return 0;
1026
1027         /*
1028          * This invokes the callback directly for now. In a later step we
1029          * convert that to use cpuhp_invoke_callback().
1030          */
1031         if (cpuhp_is_ap_state(state)) {
1032                 /*
1033                  * Note, that a function called on the AP is not
1034                  * allowed to fail.
1035                  */
1036                 if (cpu_online(cpu))
1037                         smp_call_function_single(cpu, cpuhp_on_cpu_cb, cb, 1);
1038                 return 0;
1039         }
1040
1041         /*
1042          * The non AP bound callbacks can fail on bringup. On teardown
1043          * e.g. module removal we crash for now.
1044          */
1045         ret = cb(cpu);
1046         BUG_ON(ret && !bringup);
1047         return ret;
1048 }
1049
1050 /*
1051  * Called from __cpuhp_setup_state on a recoverable failure.
1052  *
1053  * Note: The teardown callbacks for rollback are not allowed to fail!
1054  */
1055 static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
1056                                    int (*teardown)(unsigned int cpu))
1057 {
1058         int cpu;
1059
1060         if (!teardown)
1061                 return;
1062
1063         /* Roll back the already executed steps on the other cpus */
1064         for_each_present_cpu(cpu) {
1065                 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1066                 int cpustate = st->state;
1067
1068                 if (cpu >= failedcpu)
1069                         break;
1070
1071                 /* Did we invoke the startup call on that cpu ? */
1072                 if (cpustate >= state)
1073                         cpuhp_issue_call(cpu, state, teardown, false);
1074         }
1075 }
1076
1077 /*
1078  * Returns a free for dynamic slot assignment of the Online state. The states
1079  * are protected by the cpuhp_slot_states mutex and an empty slot is identified
1080  * by having no name assigned.
1081  */
1082 static int cpuhp_reserve_state(enum cpuhp_state state)
1083 {
1084         enum cpuhp_state i;
1085
1086         mutex_lock(&cpuhp_state_mutex);
1087         for (i = CPUHP_ONLINE_DYN; i <= CPUHP_ONLINE_DYN_END; i++) {
1088                 if (cpuhp_bp_states[i].name)
1089                         continue;
1090
1091                 cpuhp_bp_states[i].name = "Reserved";
1092                 mutex_unlock(&cpuhp_state_mutex);
1093                 return i;
1094         }
1095         mutex_unlock(&cpuhp_state_mutex);
1096         WARN(1, "No more dynamic states available for CPU hotplug\n");
1097         return -ENOSPC;
1098 }
1099
1100 /**
1101  * __cpuhp_setup_state - Setup the callbacks for an hotplug machine state
1102  * @state:      The state to setup
1103  * @invoke:     If true, the startup function is invoked for cpus where
1104  *              cpu state >= @state
1105  * @startup:    startup callback function
1106  * @teardown:   teardown callback function
1107  *
1108  * Returns 0 if successful, otherwise a proper error code
1109  */
1110 int __cpuhp_setup_state(enum cpuhp_state state,
1111                         const char *name, bool invoke,
1112                         int (*startup)(unsigned int cpu),
1113                         int (*teardown)(unsigned int cpu))
1114 {
1115         int cpu, ret = 0;
1116         int dyn_state = 0;
1117
1118         if (cpuhp_cb_check(state) || !name)
1119                 return -EINVAL;
1120
1121         get_online_cpus();
1122
1123         /* currently assignments for the ONLINE state are possible */
1124         if (state == CPUHP_ONLINE_DYN) {
1125                 dyn_state = 1;
1126                 ret = cpuhp_reserve_state(state);
1127                 if (ret < 0)
1128                         goto out;
1129                 state = ret;
1130         }
1131
1132         cpuhp_store_callbacks(state, name, startup, teardown);
1133
1134         if (!invoke || !startup)
1135                 goto out;
1136
1137         /*
1138          * Try to call the startup callback for each present cpu
1139          * depending on the hotplug state of the cpu.
1140          */
1141         for_each_present_cpu(cpu) {
1142                 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1143                 int cpustate = st->state;
1144
1145                 if (cpustate < state)
1146                         continue;
1147
1148                 ret = cpuhp_issue_call(cpu, state, startup, true);
1149                 if (ret) {
1150                         cpuhp_rollback_install(cpu, state, teardown);
1151                         cpuhp_store_callbacks(state, NULL, NULL, NULL);
1152                         goto out;
1153                 }
1154         }
1155 out:
1156         put_online_cpus();
1157         if (!ret && dyn_state)
1158                 return state;
1159         return ret;
1160 }
1161 EXPORT_SYMBOL(__cpuhp_setup_state);
1162
1163 /**
1164  * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state
1165  * @state:      The state to remove
1166  * @invoke:     If true, the teardown function is invoked for cpus where
1167  *              cpu state >= @state
1168  *
1169  * The teardown callback is currently not allowed to fail. Think
1170  * about module removal!
1171  */
1172 void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
1173 {
1174         int (*teardown)(unsigned int cpu) = cpuhp_get_teardown_cb(state);
1175         int cpu;
1176
1177         BUG_ON(cpuhp_cb_check(state));
1178
1179         get_online_cpus();
1180
1181         if (!invoke || !teardown)
1182                 goto remove;
1183
1184         /*
1185          * Call the teardown callback for each present cpu depending
1186          * on the hotplug state of the cpu. This function is not
1187          * allowed to fail currently!
1188          */
1189         for_each_present_cpu(cpu) {
1190                 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1191                 int cpustate = st->state;
1192
1193                 if (cpustate >= state)
1194                         cpuhp_issue_call(cpu, state, teardown, false);
1195         }
1196 remove:
1197         cpuhp_store_callbacks(state, NULL, NULL, NULL);
1198         put_online_cpus();
1199 }
1200 EXPORT_SYMBOL(__cpuhp_remove_state);
1201
1202 #if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
1203 static ssize_t show_cpuhp_state(struct device *dev,
1204                                 struct device_attribute *attr, char *buf)
1205 {
1206         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1207
1208         return sprintf(buf, "%d\n", st->state);
1209 }
1210 static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);
1211
1212 static ssize_t write_cpuhp_target(struct device *dev,
1213                                   struct device_attribute *attr,
1214                                   const char *buf, size_t count)
1215 {
1216         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1217         struct cpuhp_step *sp;
1218         int target, ret;
1219
1220         ret = kstrtoint(buf, 10, &target);
1221         if (ret)
1222                 return ret;
1223
1224 #ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL
1225         if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE)
1226                 return -EINVAL;
1227 #else
1228         if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE)
1229                 return -EINVAL;
1230 #endif
1231
1232         ret = lock_device_hotplug_sysfs();
1233         if (ret)
1234                 return ret;
1235
1236         mutex_lock(&cpuhp_state_mutex);
1237         sp = cpuhp_get_step(target);
1238         ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
1239         mutex_unlock(&cpuhp_state_mutex);
1240         if (ret)
1241                 return ret;
1242
1243         if (st->state < target)
1244                 ret = do_cpu_up(dev->id, target);
1245         else
1246                 ret = do_cpu_down(dev->id, target);
1247
1248         unlock_device_hotplug();
1249         return ret ? ret : count;
1250 }
1251
1252 static ssize_t show_cpuhp_target(struct device *dev,
1253                                  struct device_attribute *attr, char *buf)
1254 {
1255         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1256
1257         return sprintf(buf, "%d\n", st->target);
1258 }
1259 static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);
1260
1261 static struct attribute *cpuhp_cpu_attrs[] = {
1262         &dev_attr_state.attr,
1263         &dev_attr_target.attr,
1264         NULL
1265 };
1266
1267 static struct attribute_group cpuhp_cpu_attr_group = {
1268         .attrs = cpuhp_cpu_attrs,
1269         .name = "hotplug",
1270         NULL
1271 };
1272
1273 static ssize_t show_cpuhp_states(struct device *dev,
1274                                  struct device_attribute *attr, char *buf)
1275 {
1276         ssize_t cur, res = 0;
1277         int i;
1278
1279         mutex_lock(&cpuhp_state_mutex);
1280         for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) {
1281                 struct cpuhp_step *sp = cpuhp_get_step(i);
1282
1283                 if (sp->name) {
1284                         cur = sprintf(buf, "%3d: %s\n", i, sp->name);
1285                         buf += cur;
1286                         res += cur;
1287                 }
1288         }
1289         mutex_unlock(&cpuhp_state_mutex);
1290         return res;
1291 }
1292 static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL);
1293
1294 static struct attribute *cpuhp_cpu_root_attrs[] = {
1295         &dev_attr_states.attr,
1296         NULL
1297 };
1298
1299 static struct attribute_group cpuhp_cpu_root_attr_group = {
1300         .attrs = cpuhp_cpu_root_attrs,
1301         .name = "hotplug",
1302         NULL
1303 };
1304
1305 static int __init cpuhp_sysfs_init(void)
1306 {
1307         int cpu, ret;
1308
1309         ret = sysfs_create_group(&cpu_subsys.dev_root->kobj,
1310                                  &cpuhp_cpu_root_attr_group);
1311         if (ret)
1312                 return ret;
1313
1314         for_each_possible_cpu(cpu) {
1315                 struct device *dev = get_cpu_device(cpu);
1316
1317                 if (!dev)
1318                         continue;
1319                 ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group);
1320                 if (ret)
1321                         return ret;
1322         }
1323         return 0;
1324 }
1325 device_initcall(cpuhp_sysfs_init);
1326 #endif
1327
1328 /*
1329  * cpu_bit_bitmap[] is a special, "compressed" data structure that
1330  * represents all NR_CPUS bits binary values of 1<<nr.
1331  *
1332  * It is used by cpumask_of() to get a constant address to a CPU
1333  * mask value that has a single bit set only.
1334  */
1335
1336 /* cpu_bit_bitmap[0] is empty - so we can back into it */
1337 #define MASK_DECLARE_1(x)       [x+1][0] = (1UL << (x))
1338 #define MASK_DECLARE_2(x)       MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
1339 #define MASK_DECLARE_4(x)       MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
1340 #define MASK_DECLARE_8(x)       MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
1341
1342 const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
1343
1344         MASK_DECLARE_8(0),      MASK_DECLARE_8(8),
1345         MASK_DECLARE_8(16),     MASK_DECLARE_8(24),
1346 #if BITS_PER_LONG > 32
1347         MASK_DECLARE_8(32),     MASK_DECLARE_8(40),
1348         MASK_DECLARE_8(48),     MASK_DECLARE_8(56),
1349 #endif
1350 };
1351 EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
1352
1353 const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
1354 EXPORT_SYMBOL(cpu_all_bits);
1355
1356 #ifdef CONFIG_INIT_ALL_POSSIBLE
1357 struct cpumask __cpu_possible_mask __read_mostly
1358         = {CPU_BITS_ALL};
1359 #else
1360 struct cpumask __cpu_possible_mask __read_mostly;
1361 #endif
1362 EXPORT_SYMBOL(__cpu_possible_mask);
1363
1364 struct cpumask __cpu_online_mask __read_mostly;
1365 EXPORT_SYMBOL(__cpu_online_mask);
1366
1367 struct cpumask __cpu_present_mask __read_mostly;
1368 EXPORT_SYMBOL(__cpu_present_mask);
1369
1370 struct cpumask __cpu_active_mask __read_mostly;
1371 EXPORT_SYMBOL(__cpu_active_mask);
1372
1373 void init_cpu_present(const struct cpumask *src)
1374 {
1375         cpumask_copy(&__cpu_present_mask, src);
1376 }
1377
1378 void init_cpu_possible(const struct cpumask *src)
1379 {
1380         cpumask_copy(&__cpu_possible_mask, src);
1381 }
1382
1383 void init_cpu_online(const struct cpumask *src)
1384 {
1385         cpumask_copy(&__cpu_online_mask, src);
1386 }
1387
1388 /*
1389  * Activate the first processor.
1390  */
1391 void __init boot_cpu_init(void)
1392 {
1393         int cpu = smp_processor_id();
1394
1395         /* Mark the boot cpu "present", "online" etc for SMP and UP case */
1396         set_cpu_online(cpu, true);
1397         set_cpu_active(cpu, true);
1398         set_cpu_present(cpu, true);
1399         set_cpu_possible(cpu, true);
1400 }
1401
1402 /*
1403  * Must be called _AFTER_ setting up the per_cpu areas
1404  */
1405 void __init boot_cpu_state_init(void)
1406 {
1407         per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE;
1408 }