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         smpboot_park_threads(cpu);
 485
 486         /*
 487          * Prevent irq alloc/free while the dying cpu reorganizes the
 488          * interrupt affinities.
 489          */
 490         irq_lock_sparse();
 491
 492         /*
 493          * So now all preempt/rcu users must observe !cpu_active().
 494          */
 495         err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu));
 496         if (err) {
 497                 /* CPU didn't die: tell everyone.  Can't complain. */
 498                 cpu_notify_nofail(CPU_DOWN_FAILED, cpu);
 499                 irq_unlock_sparse();
 500                 return err;
 501         }
 502         BUG_ON(cpu_online(cpu));
 503
 504         /*
 505          * The migration_call() CPU_DYING callback will have removed all
 506          * runnable tasks from the cpu, there's only the idle task left now
 507          * that the migration thread is done doing the stop_machine thing.
 508          *
 509          * Wait for the stop thread to go away.
 510          */
 511         while (!per_cpu(cpu_dead_idle, cpu))
 512                 cpu_relax();
 513         smp_mb(); /* Read from cpu_dead_idle before __cpu_die(). */
 514         per_cpu(cpu_dead_idle, cpu) = false;
 515
 516         /* Interrupts are moved away from the dying cpu, reenable alloc/free */
 517         irq_unlock_sparse();
 518
 519         hotplug_cpu__broadcast_tick_pull(cpu);
 520         /* This actually kills the CPU. */
 521         __cpu_die(cpu);
 522
 523         tick_cleanup_dead_cpu(cpu);
 524         return 0;
 525 }
 526
 527 static int notify_dead(unsigned int cpu)
 528 {
 529         cpu_notify_nofail(CPU_DEAD, cpu);
 530         check_for_tasks(cpu);
 531         return 0;
 532 }
 533
 534 #else
 535 #define notify_down_prepare     NULL
 536 #define takedown_cpu            NULL
 537 #define notify_dead             NULL
 538 #define notify_dying            NULL
 539 #endif
 540
 541 #ifdef CONFIG_HOTPLUG_CPU
 542 static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st)
 543 {
 544         for (st->state++; st->state < st->target; st->state++) {
 545                 struct cpuhp_step *step = cpuhp_bp_states + st->state;
 546
 547                 if (!step->skip_onerr)
 548                         cpuhp_invoke_callback(cpu, st->state, step->startup);
 549         }
 550 }
 551
 552 /* Requires cpu_add_remove_lock to be held */
 553 static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
 554                            enum cpuhp_state target)
 555 {
 556         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
 557         int prev_state, ret = 0;
 558         bool hasdied = false;
 559
 560         if (num_online_cpus() == 1)
 561                 return -EBUSY;
 562
 563         if (!cpu_present(cpu))
 564                 return -EINVAL;
 565
 566         cpu_hotplug_begin();
 567
 568         cpuhp_tasks_frozen = tasks_frozen;
 569
 570         prev_state = st->state;
 571         st->target = target;
 572         for (; st->state > st->target; st->state--) {
 573                 struct cpuhp_step *step = cpuhp_bp_states + st->state;
 574
 575                 ret = cpuhp_invoke_callback(cpu, st->state, step->teardown);
 576                 if (ret) {
 577                         st->target = prev_state;
 578                         undo_cpu_down(cpu, st);
 579                         break;
 580                 }
 581         }
 582         hasdied = prev_state != st->state && st->state == CPUHP_OFFLINE;
 583
 584         cpu_hotplug_done();
 585         /* This post dead nonsense must die */
 586         if (!ret && hasdied)
 587                 cpu_notify_nofail(CPU_POST_DEAD, cpu);
 588         return ret;
 589 }
 590
 591 static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
 592 {
 593         int err;
 594
 595         cpu_maps_update_begin();
 596
 597         if (cpu_hotplug_disabled) {
 598                 err = -EBUSY;
 599                 goto out;
 600         }
 601
 602         err = _cpu_down(cpu, 0, target);
 603
 604 out:
 605         cpu_maps_update_done();
 606         return err;
 607 }
 608 int cpu_down(unsigned int cpu)
 609 {
 610         return do_cpu_down(cpu, CPUHP_OFFLINE);
 611 }
 612 EXPORT_SYMBOL(cpu_down);
 613 #endif /*CONFIG_HOTPLUG_CPU*/
 614
 615 /*
 616  * Unpark per-CPU smpboot kthreads at CPU-online time.
 617  */
 618 static int smpboot_thread_call(struct notifier_block *nfb,
 619                                unsigned long action, void *hcpu)
 620 {
 621         int cpu = (long)hcpu;
 622
 623         switch (action & ~CPU_TASKS_FROZEN) {
 624
 625         case CPU_DOWN_FAILED:
 626         case CPU_ONLINE:
 627                 smpboot_unpark_threads(cpu);
 628                 break;
 629
 630         default:
 631                 break;
 632         }
 633
 634         return NOTIFY_OK;
 635 }
 636
 637 static struct notifier_block smpboot_thread_notifier = {
 638         .notifier_call = smpboot_thread_call,
 639         .priority = CPU_PRI_SMPBOOT,
 640 };
 641
 642 void smpboot_thread_init(void)
 643 {
 644         register_cpu_notifier(&smpboot_thread_notifier);
 645 }
 646
 647 /**
 648  * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers
 649  * @cpu: cpu that just started
 650  *
 651  * This function calls the cpu_chain notifiers with CPU_STARTING.
 652  * It must be called by the arch code on the new cpu, before the new cpu
 653  * enables interrupts and before the "boot" cpu returns from __cpu_up().
 654  */
 655 void notify_cpu_starting(unsigned int cpu)
 656 {
 657         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
 658         enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
 659
 660         while (st->state < target) {
 661                 struct cpuhp_step *step;
 662
 663                 st->state++;
 664                 step = cpuhp_ap_states + st->state;
 665                 cpuhp_invoke_callback(cpu, st->state, step->startup);
 666         }
 667 }
 668
 669 /*
 670  * Called from the idle task. We need to set active here, so we can kick off
 671  * the stopper thread.
 672  */
 673 static int cpuhp_set_cpu_active(unsigned int cpu)
 674 {
 675         /* The cpu is marked online, set it active now */
 676         set_cpu_active(cpu, true);
 677         /* Unpark the stopper thread */
 678         stop_machine_unpark(cpu);
 679         return 0;
 680 }
 681
 682 static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st)
 683 {
 684         for (st->state--; st->state > st->target; st->state--) {
 685                 struct cpuhp_step *step = cpuhp_bp_states + st->state;
 686
 687                 if (!step->skip_onerr)
 688                         cpuhp_invoke_callback(cpu, st->state, step->teardown);
 689         }
 690 }
 691
 692 /* Requires cpu_add_remove_lock to be held */
 693 static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
 694 {
 695         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
 696         struct task_struct *idle;
 697         int prev_state, ret = 0;
 698
 699         cpu_hotplug_begin();
 700
 701         if (!cpu_present(cpu)) {
 702                 ret = -EINVAL;
 703                 goto out;
 704         }
 705
 706         /*
 707          * The caller of do_cpu_up might have raced with another
 708          * caller. Ignore it for now.
 709          */
 710         if (st->state >= target)
 711                 goto out;
 712
 713         if (st->state == CPUHP_OFFLINE) {
 714                 /* Let it fail before we try to bring the cpu up */
 715                 idle = idle_thread_get(cpu);
 716                 if (IS_ERR(idle)) {
 717                         ret = PTR_ERR(idle);
 718                         goto out;
 719                 }
 720         }
 721
 722         cpuhp_tasks_frozen = tasks_frozen;
 723
 724         prev_state = st->state;
 725         st->target = target;
 726         while (st->state < st->target) {
 727                 struct cpuhp_step *step;
 728
 729                 st->state++;
 730                 step = cpuhp_bp_states + st->state;
 731                 ret = cpuhp_invoke_callback(cpu, st->state, step->startup);
 732                 if (ret) {
 733                         st->target = prev_state;
 734                         undo_cpu_up(cpu, st);
 735                         break;
 736                 }
 737         }
 738 out:
 739         cpu_hotplug_done();
 740         return ret;
 741 }
 742
 743 static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
 744 {
 745         int err = 0;
 746
 747         if (!cpu_possible(cpu)) {
 748                 pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
 749                        cpu);
 750 #if defined(CONFIG_IA64)
 751                 pr_err("please check additional_cpus= boot parameter\n");
 752 #endif
 753                 return -EINVAL;
 754         }
 755
 756         err = try_online_node(cpu_to_node(cpu));
 757         if (err)
 758                 return err;
 759
 760         cpu_maps_update_begin();
 761
 762         if (cpu_hotplug_disabled) {
 763                 err = -EBUSY;
 764                 goto out;
 765         }
 766
 767         err = _cpu_up(cpu, 0, target);
 768 out:
 769         cpu_maps_update_done();
 770         return err;
 771 }
 772
 773 int cpu_up(unsigned int cpu)
 774 {
 775         return do_cpu_up(cpu, CPUHP_ONLINE);
 776 }
 777 EXPORT_SYMBOL_GPL(cpu_up);
 778
 779 #ifdef CONFIG_PM_SLEEP_SMP
 780 static cpumask_var_t frozen_cpus;
 781
 782 int disable_nonboot_cpus(void)
 783 {
 784         int cpu, first_cpu, error = 0;
 785
 786         cpu_maps_update_begin();
 787         first_cpu = cpumask_first(cpu_online_mask);
 788         /*
 789          * We take down all of the non-boot CPUs in one shot to avoid races
 790          * with the userspace trying to use the CPU hotplug at the same time
 791          */
 792         cpumask_clear(frozen_cpus);
 793
 794         pr_info("Disabling non-boot CPUs ...\n");
 795         for_each_online_cpu(cpu) {
 796                 if (cpu == first_cpu)
 797                         continue;
 798                 trace_suspend_resume(TPS("CPU_OFF"), cpu, true);
 799                 error = _cpu_down(cpu, 1, CPUHP_OFFLINE);
 800                 trace_suspend_resume(TPS("CPU_OFF"), cpu, false);
 801                 if (!error)
 802                         cpumask_set_cpu(cpu, frozen_cpus);
 803                 else {
 804                         pr_err("Error taking CPU%d down: %d\n", cpu, error);
 805                         break;
 806                 }
 807         }
 808
 809         if (!error)
 810                 BUG_ON(num_online_cpus() > 1);
 811         else
 812                 pr_err("Non-boot CPUs are not disabled\n");
 813
 814         /*
 815          * Make sure the CPUs won't be enabled by someone else. We need to do
 816          * this even in case of failure as all disable_nonboot_cpus() users are
 817          * supposed to do enable_nonboot_cpus() on the failure path.
 818          */
 819         cpu_hotplug_disabled++;
 820
 821         cpu_maps_update_done();
 822         return error;
 823 }
 824
 825 void __weak arch_enable_nonboot_cpus_begin(void)
 826 {
 827 }
 828
 829 void __weak arch_enable_nonboot_cpus_end(void)
 830 {
 831 }
 832
 833 void enable_nonboot_cpus(void)
 834 {
 835         int cpu, error;
 836
 837         /* Allow everyone to use the CPU hotplug again */
 838         cpu_maps_update_begin();
 839         WARN_ON(--cpu_hotplug_disabled < 0);
 840         if (cpumask_empty(frozen_cpus))
 841                 goto out;
 842
 843         pr_info("Enabling non-boot CPUs ...\n");
 844
 845         arch_enable_nonboot_cpus_begin();
 846
 847         for_each_cpu(cpu, frozen_cpus) {
 848                 trace_suspend_resume(TPS("CPU_ON"), cpu, true);
 849                 error = _cpu_up(cpu, 1, CPUHP_ONLINE);
 850                 trace_suspend_resume(TPS("CPU_ON"), cpu, false);
 851                 if (!error) {
 852                         pr_info("CPU%d is up\n", cpu);
 853                         continue;
 854                 }
 855                 pr_warn("Error taking CPU%d up: %d\n", cpu, error);
 856         }
 857
 858         arch_enable_nonboot_cpus_end();
 859
 860         cpumask_clear(frozen_cpus);
 861 out:
 862         cpu_maps_update_done();
 863 }
 864
 865 static int __init alloc_frozen_cpus(void)
 866 {
 867         if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
 868                 return -ENOMEM;
 869         return 0;
 870 }
 871 core_initcall(alloc_frozen_cpus);
 872
 873 /*
 874  * When callbacks for CPU hotplug notifications are being executed, we must
 875  * ensure that the state of the system with respect to the tasks being frozen
 876  * or not, as reported by the notification, remains unchanged *throughout the
 877  * duration* of the execution of the callbacks.
 878  * Hence we need to prevent the freezer from racing with regular CPU hotplug.
 879  *
 880  * This synchronization is implemented by mutually excluding regular CPU
 881  * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
 882  * Hibernate notifications.
 883  */
 884 static int
 885 cpu_hotplug_pm_callback(struct notifier_block *nb,
 886                         unsigned long action, void *ptr)
 887 {
 888         switch (action) {
 889
 890         case PM_SUSPEND_PREPARE:
 891         case PM_HIBERNATION_PREPARE:
 892                 cpu_hotplug_disable();
 893                 break;
 894
 895         case PM_POST_SUSPEND:
 896         case PM_POST_HIBERNATION:
 897                 cpu_hotplug_enable();
 898                 break;
 899
 900         default:
 901                 return NOTIFY_DONE;
 902         }
 903
 904         return NOTIFY_OK;
 905 }
 906
 907
 908 static int __init cpu_hotplug_pm_sync_init(void)
 909 {
 910         /*
 911          * cpu_hotplug_pm_callback has higher priority than x86
 912          * bsp_pm_callback which depends on cpu_hotplug_pm_callback
 913          * to disable cpu hotplug to avoid cpu hotplug race.
 914          */
 915         pm_notifier(cpu_hotplug_pm_callback, 0);
 916         return 0;
 917 }
 918 core_initcall(cpu_hotplug_pm_sync_init);
 919
 920 #endif /* CONFIG_PM_SLEEP_SMP */
 921
 922 #endif /* CONFIG_SMP */
 923
 924 /* Boot processor state steps */
 925 static struct cpuhp_step cpuhp_bp_states[] = {
 926         [CPUHP_OFFLINE] = {
 927                 .name                   = "offline",
 928                 .startup                = NULL,
 929                 .teardown               = NULL,
 930         },
 931 #ifdef CONFIG_SMP
 932         [CPUHP_CREATE_THREADS]= {
 933                 .name                   = "threads:create",
 934                 .startup                = smpboot_create_threads,
 935                 .teardown               = NULL,
 936                 .cant_stop              = true,
 937         },
 938         [CPUHP_NOTIFY_PREPARE] = {
 939                 .name                   = "notify:prepare",
 940                 .startup                = notify_prepare,
 941                 .teardown               = notify_dead,
 942                 .skip_onerr             = true,
 943                 .cant_stop              = true,
 944         },
 945         [CPUHP_BRINGUP_CPU] = {
 946                 .name                   = "cpu:bringup",
 947                 .startup                = bringup_cpu,
 948                 .teardown               = NULL,
 949                 .cant_stop              = true,
 950         },
 951         [CPUHP_TEARDOWN_CPU] = {
 952                 .name                   = "cpu:teardown",
 953                 .startup                = NULL,
 954                 .teardown               = takedown_cpu,
 955                 .cant_stop              = true,
 956         },
 957         [CPUHP_CPU_SET_ACTIVE] = {
 958                 .name                   = "cpu:active",
 959                 .startup                = cpuhp_set_cpu_active,
 960                 .teardown               = NULL,
 961         },
 962         [CPUHP_NOTIFY_ONLINE] = {
 963                 .name                   = "notify:online",
 964                 .startup                = notify_online,
 965                 .teardown               = notify_down_prepare,
 966                 .cant_stop              = true,
 967         },
 968 #endif
 969         [CPUHP_ONLINE] = {
 970                 .name                   = "online",
 971                 .startup                = NULL,
 972                 .teardown               = NULL,
 973         },
 974 };
 975
 976 /* Application processor state steps */
 977 static struct cpuhp_step cpuhp_ap_states[] = {
 978 #ifdef CONFIG_SMP
 979         [CPUHP_AP_NOTIFY_STARTING] = {
 980                 .name                   = "notify:starting",
 981                 .startup                = notify_starting,
 982                 .teardown               = notify_dying,
 983                 .skip_onerr             = true,
 984                 .cant_stop              = true,
 985         },
 986 #endif
 987         [CPUHP_ONLINE] = {
 988                 .name                   = "online",
 989                 .startup                = NULL,
 990                 .teardown               = NULL,
 991         },
 992 };
 993
 994 /* Sanity check for callbacks */
 995 static int cpuhp_cb_check(enum cpuhp_state state)
 996 {
 997         if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE)
 998                 return -EINVAL;
 999         return 0;
1000 }
1001
1002 static bool cpuhp_is_ap_state(enum cpuhp_state state)
1003 {
1004         return (state > CPUHP_AP_OFFLINE && state < CPUHP_AP_ONLINE);
1005 }
1006
1007 static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
1008 {
1009         struct cpuhp_step *sp;
1010
1011         sp = cpuhp_is_ap_state(state) ? cpuhp_ap_states : cpuhp_bp_states;
1012         return sp + state;
1013 }
1014
1015 static void cpuhp_store_callbacks(enum cpuhp_state state,
1016                                   const char *name,
1017                                   int (*startup)(unsigned int cpu),
1018                                   int (*teardown)(unsigned int cpu))
1019 {
1020         /* (Un)Install the callbacks for further cpu hotplug operations */
1021         struct cpuhp_step *sp;
1022
1023         mutex_lock(&cpuhp_state_mutex);
1024         sp = cpuhp_get_step(state);
1025         sp->startup = startup;
1026         sp->teardown = teardown;
1027         sp->name = name;
1028         mutex_unlock(&cpuhp_state_mutex);
1029 }
1030
1031 static void *cpuhp_get_teardown_cb(enum cpuhp_state state)
1032 {
1033         return cpuhp_get_step(state)->teardown;
1034 }
1035
1036 /* Helper function to run callback on the target cpu */
1037 static void cpuhp_on_cpu_cb(void *__cb)
1038 {
1039         int (*cb)(unsigned int cpu) = __cb;
1040
1041         BUG_ON(cb(smp_processor_id()));
1042 }
1043
1044 /*
1045  * Call the startup/teardown function for a step either on the AP or
1046  * on the current CPU.
1047  */
1048 static int cpuhp_issue_call(int cpu, enum cpuhp_state state,
1049                             int (*cb)(unsigned int), bool bringup)
1050 {
1051         int ret;
1052
1053         if (!cb)
1054                 return 0;
1055
1056         /*
1057          * This invokes the callback directly for now. In a later step we
1058          * convert that to use cpuhp_invoke_callback().
1059          */
1060         if (cpuhp_is_ap_state(state)) {
1061                 /*
1062                  * Note, that a function called on the AP is not
1063                  * allowed to fail.
1064                  */
1065                 if (cpu_online(cpu))
1066                         smp_call_function_single(cpu, cpuhp_on_cpu_cb, cb, 1);
1067                 return 0;
1068         }
1069
1070         /*
1071          * The non AP bound callbacks can fail on bringup. On teardown
1072          * e.g. module removal we crash for now.
1073          */
1074         ret = cb(cpu);
1075         BUG_ON(ret && !bringup);
1076         return ret;
1077 }
1078
1079 /*
1080  * Called from __cpuhp_setup_state on a recoverable failure.
1081  *
1082  * Note: The teardown callbacks for rollback are not allowed to fail!
1083  */
1084 static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
1085                                    int (*teardown)(unsigned int cpu))
1086 {
1087         int cpu;
1088
1089         if (!teardown)
1090                 return;
1091
1092         /* Roll back the already executed steps on the other cpus */
1093         for_each_present_cpu(cpu) {
1094                 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1095                 int cpustate = st->state;
1096
1097                 if (cpu >= failedcpu)
1098                         break;
1099
1100                 /* Did we invoke the startup call on that cpu ? */
1101                 if (cpustate >= state)
1102                         cpuhp_issue_call(cpu, state, teardown, false);
1103         }
1104 }
1105
1106 /*
1107  * Returns a free for dynamic slot assignment of the Online state. The states
1108  * are protected by the cpuhp_slot_states mutex and an empty slot is identified
1109  * by having no name assigned.
1110  */
1111 static int cpuhp_reserve_state(enum cpuhp_state state)
1112 {
1113         enum cpuhp_state i;
1114
1115         mutex_lock(&cpuhp_state_mutex);
1116         for (i = CPUHP_ONLINE_DYN; i <= CPUHP_ONLINE_DYN_END; i++) {
1117                 if (cpuhp_bp_states[i].name)
1118                         continue;
1119
1120                 cpuhp_bp_states[i].name = "Reserved";
1121                 mutex_unlock(&cpuhp_state_mutex);
1122                 return i;
1123         }
1124         mutex_unlock(&cpuhp_state_mutex);
1125         WARN(1, "No more dynamic states available for CPU hotplug\n");
1126         return -ENOSPC;
1127 }
1128
1129 /**
1130  * __cpuhp_setup_state - Setup the callbacks for an hotplug machine state
1131  * @state:      The state to setup
1132  * @invoke:     If true, the startup function is invoked for cpus where
1133  *              cpu state >= @state
1134  * @startup:    startup callback function
1135  * @teardown:   teardown callback function
1136  *
1137  * Returns 0 if successful, otherwise a proper error code
1138  */
1139 int __cpuhp_setup_state(enum cpuhp_state state,
1140                         const char *name, bool invoke,
1141                         int (*startup)(unsigned int cpu),
1142                         int (*teardown)(unsigned int cpu))
1143 {
1144         int cpu, ret = 0;
1145         int dyn_state = 0;
1146
1147         if (cpuhp_cb_check(state) || !name)
1148                 return -EINVAL;
1149
1150         get_online_cpus();
1151
1152         /* currently assignments for the ONLINE state are possible */
1153         if (state == CPUHP_ONLINE_DYN) {
1154                 dyn_state = 1;
1155                 ret = cpuhp_reserve_state(state);
1156                 if (ret < 0)
1157                         goto out;
1158                 state = ret;
1159         }
1160
1161         cpuhp_store_callbacks(state, name, startup, teardown);
1162
1163         if (!invoke || !startup)
1164                 goto out;
1165
1166         /*
1167          * Try to call the startup callback for each present cpu
1168          * depending on the hotplug state of the cpu.
1169          */
1170         for_each_present_cpu(cpu) {
1171                 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1172                 int cpustate = st->state;
1173
1174                 if (cpustate < state)
1175                         continue;
1176
1177                 ret = cpuhp_issue_call(cpu, state, startup, true);
1178                 if (ret) {
1179                         cpuhp_rollback_install(cpu, state, teardown);
1180                         cpuhp_store_callbacks(state, NULL, NULL, NULL);
1181                         goto out;
1182                 }
1183         }
1184 out:
1185         put_online_cpus();
1186         if (!ret && dyn_state)
1187                 return state;
1188         return ret;
1189 }
1190 EXPORT_SYMBOL(__cpuhp_setup_state);
1191
1192 /**
1193  * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state
1194  * @state:      The state to remove
1195  * @invoke:     If true, the teardown function is invoked for cpus where
1196  *              cpu state >= @state
1197  *
1198  * The teardown callback is currently not allowed to fail. Think
1199  * about module removal!
1200  */
1201 void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
1202 {
1203         int (*teardown)(unsigned int cpu) = cpuhp_get_teardown_cb(state);
1204         int cpu;
1205
1206         BUG_ON(cpuhp_cb_check(state));
1207
1208         get_online_cpus();
1209
1210         if (!invoke || !teardown)
1211                 goto remove;
1212
1213         /*
1214          * Call the teardown callback for each present cpu depending
1215          * on the hotplug state of the cpu. This function is not
1216          * allowed to fail currently!
1217          */
1218         for_each_present_cpu(cpu) {
1219                 struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
1220                 int cpustate = st->state;
1221
1222                 if (cpustate >= state)
1223                         cpuhp_issue_call(cpu, state, teardown, false);
1224         }
1225 remove:
1226         cpuhp_store_callbacks(state, NULL, NULL, NULL);
1227         put_online_cpus();
1228 }
1229 EXPORT_SYMBOL(__cpuhp_remove_state);
1230
1231 #if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
1232 static ssize_t show_cpuhp_state(struct device *dev,
1233                                 struct device_attribute *attr, char *buf)
1234 {
1235         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1236
1237         return sprintf(buf, "%d\n", st->state);
1238 }
1239 static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);
1240
1241 static ssize_t write_cpuhp_target(struct device *dev,
1242                                   struct device_attribute *attr,
1243                                   const char *buf, size_t count)
1244 {
1245         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1246         struct cpuhp_step *sp;
1247         int target, ret;
1248
1249         ret = kstrtoint(buf, 10, &target);
1250         if (ret)
1251                 return ret;
1252
1253 #ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL
1254         if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE)
1255                 return -EINVAL;
1256 #else
1257         if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE)
1258                 return -EINVAL;
1259 #endif
1260
1261         ret = lock_device_hotplug_sysfs();
1262         if (ret)
1263                 return ret;
1264
1265         mutex_lock(&cpuhp_state_mutex);
1266         sp = cpuhp_get_step(target);
1267         ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
1268         mutex_unlock(&cpuhp_state_mutex);
1269         if (ret)
1270                 return ret;
1271
1272         if (st->state < target)
1273                 ret = do_cpu_up(dev->id, target);
1274         else
1275                 ret = do_cpu_down(dev->id, target);
1276
1277         unlock_device_hotplug();
1278         return ret ? ret : count;
1279 }
1280
1281 static ssize_t show_cpuhp_target(struct device *dev,
1282                                  struct device_attribute *attr, char *buf)
1283 {
1284         struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
1285
1286         return sprintf(buf, "%d\n", st->target);
1287 }
1288 static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);
1289
1290 static struct attribute *cpuhp_cpu_attrs[] = {
1291         &dev_attr_state.attr,
1292         &dev_attr_target.attr,
1293         NULL
1294 };
1295
1296 static struct attribute_group cpuhp_cpu_attr_group = {
1297         .attrs = cpuhp_cpu_attrs,
1298         .name = "hotplug",
1299         NULL
1300 };
1301
1302 static ssize_t show_cpuhp_states(struct device *dev,
1303                                  struct device_attribute *attr, char *buf)
1304 {
1305         ssize_t cur, res = 0;
1306         int i;
1307
1308         mutex_lock(&cpuhp_state_mutex);
1309         for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) {
1310                 struct cpuhp_step *sp = cpuhp_get_step(i);
1311
1312                 if (sp->name) {
1313                         cur = sprintf(buf, "%3d: %s\n", i, sp->name);
1314                         buf += cur;
1315                         res += cur;
1316                 }
1317         }
1318         mutex_unlock(&cpuhp_state_mutex);
1319         return res;
1320 }
1321 static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL);
1322
1323 static struct attribute *cpuhp_cpu_root_attrs[] = {
1324         &dev_attr_states.attr,
1325         NULL
1326 };
1327
1328 static struct attribute_group cpuhp_cpu_root_attr_group = {
1329         .attrs = cpuhp_cpu_root_attrs,
1330         .name = "hotplug",
1331         NULL
1332 };
1333
1334 static int __init cpuhp_sysfs_init(void)
1335 {
1336         int cpu, ret;
1337
1338         ret = sysfs_create_group(&cpu_subsys.dev_root->kobj,
1339                                  &cpuhp_cpu_root_attr_group);
1340         if (ret)
1341                 return ret;
1342
1343         for_each_possible_cpu(cpu) {
1344                 struct device *dev = get_cpu_device(cpu);
1345
1346                 if (!dev)
1347                         continue;
1348                 ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group);
1349                 if (ret)
1350                         return ret;
1351         }
1352         return 0;
1353 }
1354 device_initcall(cpuhp_sysfs_init);
1355 #endif
1356
1357 /*
1358  * cpu_bit_bitmap[] is a special, "compressed" data structure that
1359  * represents all NR_CPUS bits binary values of 1<<nr.
1360  *
1361  * It is used by cpumask_of() to get a constant address to a CPU
1362  * mask value that has a single bit set only.
1363  */
1364
1365 /* cpu_bit_bitmap[0] is empty - so we can back into it */
1366 #define MASK_DECLARE_1(x)       [x+1][0] = (1UL << (x))
1367 #define MASK_DECLARE_2(x)       MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
1368 #define MASK_DECLARE_4(x)       MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
1369 #define MASK_DECLARE_8(x)       MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
1370
1371 const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
1372
1373         MASK_DECLARE_8(0),      MASK_DECLARE_8(8),
1374         MASK_DECLARE_8(16),     MASK_DECLARE_8(24),
1375 #if BITS_PER_LONG > 32
1376         MASK_DECLARE_8(32),     MASK_DECLARE_8(40),
1377         MASK_DECLARE_8(48),     MASK_DECLARE_8(56),
1378 #endif
1379 };
1380 EXPORT_SYMBOL_GPL(cpu_bit_bitmap);
1381
1382 const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
1383 EXPORT_SYMBOL(cpu_all_bits);
1384
1385 #ifdef CONFIG_INIT_ALL_POSSIBLE
1386 struct cpumask __cpu_possible_mask __read_mostly
1387         = {CPU_BITS_ALL};
1388 #else
1389 struct cpumask __cpu_possible_mask __read_mostly;
1390 #endif
1391 EXPORT_SYMBOL(__cpu_possible_mask);
1392
1393 struct cpumask __cpu_online_mask __read_mostly;
1394 EXPORT_SYMBOL(__cpu_online_mask);
1395
1396 struct cpumask __cpu_present_mask __read_mostly;
1397 EXPORT_SYMBOL(__cpu_present_mask);
1398
1399 struct cpumask __cpu_active_mask __read_mostly;
1400 EXPORT_SYMBOL(__cpu_active_mask);
1401
1402 void init_cpu_present(const struct cpumask *src)
1403 {
1404         cpumask_copy(&__cpu_present_mask, src);
1405 }
1406
1407 void init_cpu_possible(const struct cpumask *src)
1408 {
1409         cpumask_copy(&__cpu_possible_mask, src);
1410 }
1411
1412 void init_cpu_online(const struct cpumask *src)
1413 {
1414         cpumask_copy(&__cpu_online_mask, src);
1415 }
1416
1417 /*
1418  * Activate the first processor.
1419  */
1420 void __init boot_cpu_init(void)
1421 {
1422         int cpu = smp_processor_id();
1423
1424         /* Mark the boot cpu "present", "online" etc for SMP and UP case */
1425         set_cpu_online(cpu, true);
1426         set_cpu_active(cpu, true);
1427         set_cpu_present(cpu, true);
1428         set_cpu_possible(cpu, true);
1429 }
1430
1431 /*
1432  * Must be called _AFTER_ setting up the per_cpu areas
1433  */
1434 void __init boot_cpu_state_init(void)
1435 {
1436         per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE;
1437 }