Merge branch 'spectre' of git://git.armlinux.org.uk/~rmk/linux-arm
[sfrench/cifs-2.6.git] / arch / arm / kernel / smp.c
1 /*
2  *  linux/arch/arm/kernel/smp.c
3  *
4  *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 #include <linux/module.h>
11 #include <linux/delay.h>
12 #include <linux/init.h>
13 #include <linux/spinlock.h>
14 #include <linux/sched/mm.h>
15 #include <linux/sched/hotplug.h>
16 #include <linux/sched/task_stack.h>
17 #include <linux/interrupt.h>
18 #include <linux/cache.h>
19 #include <linux/profile.h>
20 #include <linux/errno.h>
21 #include <linux/mm.h>
22 #include <linux/err.h>
23 #include <linux/cpu.h>
24 #include <linux/seq_file.h>
25 #include <linux/irq.h>
26 #include <linux/nmi.h>
27 #include <linux/percpu.h>
28 #include <linux/clockchips.h>
29 #include <linux/completion.h>
30 #include <linux/cpufreq.h>
31 #include <linux/irq_work.h>
32
33 #include <linux/atomic.h>
34 #include <asm/bugs.h>
35 #include <asm/smp.h>
36 #include <asm/cacheflush.h>
37 #include <asm/cpu.h>
38 #include <asm/cputype.h>
39 #include <asm/exception.h>
40 #include <asm/idmap.h>
41 #include <asm/topology.h>
42 #include <asm/mmu_context.h>
43 #include <asm/pgtable.h>
44 #include <asm/pgalloc.h>
45 #include <asm/procinfo.h>
46 #include <asm/processor.h>
47 #include <asm/sections.h>
48 #include <asm/tlbflush.h>
49 #include <asm/ptrace.h>
50 #include <asm/smp_plat.h>
51 #include <asm/virt.h>
52 #include <asm/mach/arch.h>
53 #include <asm/mpu.h>
54
55 #define CREATE_TRACE_POINTS
56 #include <trace/events/ipi.h>
57
58 /*
59  * as from 2.5, kernels no longer have an init_tasks structure
60  * so we need some other way of telling a new secondary core
61  * where to place its SVC stack
62  */
63 struct secondary_data secondary_data;
64
65 /*
66  * control for which core is the next to come out of the secondary
67  * boot "holding pen"
68  */
69 volatile int pen_release = -1;
70
71 enum ipi_msg_type {
72         IPI_WAKEUP,
73         IPI_TIMER,
74         IPI_RESCHEDULE,
75         IPI_CALL_FUNC,
76         IPI_CPU_STOP,
77         IPI_IRQ_WORK,
78         IPI_COMPLETION,
79         IPI_CPU_BACKTRACE,
80         /*
81          * SGI8-15 can be reserved by secure firmware, and thus may
82          * not be usable by the kernel. Please keep the above limited
83          * to at most 8 entries.
84          */
85 };
86
87 static DECLARE_COMPLETION(cpu_running);
88
89 static struct smp_operations smp_ops __ro_after_init;
90
91 void __init smp_set_ops(const struct smp_operations *ops)
92 {
93         if (ops)
94                 smp_ops = *ops;
95 };
96
97 static unsigned long get_arch_pgd(pgd_t *pgd)
98 {
99 #ifdef CONFIG_ARM_LPAE
100         return __phys_to_pfn(virt_to_phys(pgd));
101 #else
102         return virt_to_phys(pgd);
103 #endif
104 }
105
106 #if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
107 static int secondary_biglittle_prepare(unsigned int cpu)
108 {
109         if (!cpu_vtable[cpu])
110                 cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL);
111
112         return cpu_vtable[cpu] ? 0 : -ENOMEM;
113 }
114
115 static void secondary_biglittle_init(void)
116 {
117         init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
118 }
119 #else
120 static int secondary_biglittle_prepare(unsigned int cpu)
121 {
122         return 0;
123 }
124
125 static void secondary_biglittle_init(void)
126 {
127 }
128 #endif
129
130 int __cpu_up(unsigned int cpu, struct task_struct *idle)
131 {
132         int ret;
133
134         if (!smp_ops.smp_boot_secondary)
135                 return -ENOSYS;
136
137         ret = secondary_biglittle_prepare(cpu);
138         if (ret)
139                 return ret;
140
141         /*
142          * We need to tell the secondary core where to find
143          * its stack and the page tables.
144          */
145         secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
146 #ifdef CONFIG_ARM_MPU
147         secondary_data.mpu_rgn_info = &mpu_rgn_info;
148 #endif
149
150 #ifdef CONFIG_MMU
151         secondary_data.pgdir = virt_to_phys(idmap_pgd);
152         secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
153 #endif
154         sync_cache_w(&secondary_data);
155
156         /*
157          * Now bring the CPU into our world.
158          */
159         ret = smp_ops.smp_boot_secondary(cpu, idle);
160         if (ret == 0) {
161                 /*
162                  * CPU was successfully started, wait for it
163                  * to come online or time out.
164                  */
165                 wait_for_completion_timeout(&cpu_running,
166                                                  msecs_to_jiffies(1000));
167
168                 if (!cpu_online(cpu)) {
169                         pr_crit("CPU%u: failed to come online\n", cpu);
170                         ret = -EIO;
171                 }
172         } else {
173                 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
174         }
175
176
177         memset(&secondary_data, 0, sizeof(secondary_data));
178         return ret;
179 }
180
181 /* platform specific SMP operations */
182 void __init smp_init_cpus(void)
183 {
184         if (smp_ops.smp_init_cpus)
185                 smp_ops.smp_init_cpus();
186 }
187
188 int platform_can_secondary_boot(void)
189 {
190         return !!smp_ops.smp_boot_secondary;
191 }
192
193 int platform_can_cpu_hotplug(void)
194 {
195 #ifdef CONFIG_HOTPLUG_CPU
196         if (smp_ops.cpu_kill)
197                 return 1;
198 #endif
199
200         return 0;
201 }
202
203 #ifdef CONFIG_HOTPLUG_CPU
204 static int platform_cpu_kill(unsigned int cpu)
205 {
206         if (smp_ops.cpu_kill)
207                 return smp_ops.cpu_kill(cpu);
208         return 1;
209 }
210
211 static int platform_cpu_disable(unsigned int cpu)
212 {
213         if (smp_ops.cpu_disable)
214                 return smp_ops.cpu_disable(cpu);
215
216         return 0;
217 }
218
219 int platform_can_hotplug_cpu(unsigned int cpu)
220 {
221         /* cpu_die must be specified to support hotplug */
222         if (!smp_ops.cpu_die)
223                 return 0;
224
225         if (smp_ops.cpu_can_disable)
226                 return smp_ops.cpu_can_disable(cpu);
227
228         /*
229          * By default, allow disabling all CPUs except the first one,
230          * since this is special on a lot of platforms, e.g. because
231          * of clock tick interrupts.
232          */
233         return cpu != 0;
234 }
235
236 /*
237  * __cpu_disable runs on the processor to be shutdown.
238  */
239 int __cpu_disable(void)
240 {
241         unsigned int cpu = smp_processor_id();
242         int ret;
243
244         ret = platform_cpu_disable(cpu);
245         if (ret)
246                 return ret;
247
248         /*
249          * Take this CPU offline.  Once we clear this, we can't return,
250          * and we must not schedule until we're ready to give up the cpu.
251          */
252         set_cpu_online(cpu, false);
253
254         /*
255          * OK - migrate IRQs away from this CPU
256          */
257         migrate_irqs();
258
259         /*
260          * Flush user cache and TLB mappings, and then remove this CPU
261          * from the vm mask set of all processes.
262          *
263          * Caches are flushed to the Level of Unification Inner Shareable
264          * to write-back dirty lines to unified caches shared by all CPUs.
265          */
266         flush_cache_louis();
267         local_flush_tlb_all();
268
269         return 0;
270 }
271
272 static DECLARE_COMPLETION(cpu_died);
273
274 /*
275  * called on the thread which is asking for a CPU to be shutdown -
276  * waits until shutdown has completed, or it is timed out.
277  */
278 void __cpu_die(unsigned int cpu)
279 {
280         if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
281                 pr_err("CPU%u: cpu didn't die\n", cpu);
282                 return;
283         }
284         pr_debug("CPU%u: shutdown\n", cpu);
285
286         clear_tasks_mm_cpumask(cpu);
287         /*
288          * platform_cpu_kill() is generally expected to do the powering off
289          * and/or cutting of clocks to the dying CPU.  Optionally, this may
290          * be done by the CPU which is dying in preference to supporting
291          * this call, but that means there is _no_ synchronisation between
292          * the requesting CPU and the dying CPU actually losing power.
293          */
294         if (!platform_cpu_kill(cpu))
295                 pr_err("CPU%u: unable to kill\n", cpu);
296 }
297
298 /*
299  * Called from the idle thread for the CPU which has been shutdown.
300  *
301  * Note that we disable IRQs here, but do not re-enable them
302  * before returning to the caller. This is also the behaviour
303  * of the other hotplug-cpu capable cores, so presumably coming
304  * out of idle fixes this.
305  */
306 void arch_cpu_idle_dead(void)
307 {
308         unsigned int cpu = smp_processor_id();
309
310         idle_task_exit();
311
312         local_irq_disable();
313
314         /*
315          * Flush the data out of the L1 cache for this CPU.  This must be
316          * before the completion to ensure that data is safely written out
317          * before platform_cpu_kill() gets called - which may disable
318          * *this* CPU and power down its cache.
319          */
320         flush_cache_louis();
321
322         /*
323          * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
324          * this returns, power and/or clocks can be removed at any point
325          * from this CPU and its cache by platform_cpu_kill().
326          */
327         complete(&cpu_died);
328
329         /*
330          * Ensure that the cache lines associated with that completion are
331          * written out.  This covers the case where _this_ CPU is doing the
332          * powering down, to ensure that the completion is visible to the
333          * CPU waiting for this one.
334          */
335         flush_cache_louis();
336
337         /*
338          * The actual CPU shutdown procedure is at least platform (if not
339          * CPU) specific.  This may remove power, or it may simply spin.
340          *
341          * Platforms are generally expected *NOT* to return from this call,
342          * although there are some which do because they have no way to
343          * power down the CPU.  These platforms are the _only_ reason we
344          * have a return path which uses the fragment of assembly below.
345          *
346          * The return path should not be used for platforms which can
347          * power off the CPU.
348          */
349         if (smp_ops.cpu_die)
350                 smp_ops.cpu_die(cpu);
351
352         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
353                 cpu);
354
355         /*
356          * Do not return to the idle loop - jump back to the secondary
357          * cpu initialisation.  There's some initialisation which needs
358          * to be repeated to undo the effects of taking the CPU offline.
359          */
360         __asm__("mov    sp, %0\n"
361         "       mov     fp, #0\n"
362         "       b       secondary_start_kernel"
363                 :
364                 : "r" (task_stack_page(current) + THREAD_SIZE - 8));
365 }
366 #endif /* CONFIG_HOTPLUG_CPU */
367
368 /*
369  * Called by both boot and secondaries to move global data into
370  * per-processor storage.
371  */
372 static void smp_store_cpu_info(unsigned int cpuid)
373 {
374         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
375
376         cpu_info->loops_per_jiffy = loops_per_jiffy;
377         cpu_info->cpuid = read_cpuid_id();
378
379         store_cpu_topology(cpuid);
380 }
381
382 /*
383  * This is the secondary CPU boot entry.  We're using this CPUs
384  * idle thread stack, but a set of temporary page tables.
385  */
386 asmlinkage void secondary_start_kernel(void)
387 {
388         struct mm_struct *mm = &init_mm;
389         unsigned int cpu;
390
391         secondary_biglittle_init();
392
393         /*
394          * The identity mapping is uncached (strongly ordered), so
395          * switch away from it before attempting any exclusive accesses.
396          */
397         cpu_switch_mm(mm->pgd, mm);
398         local_flush_bp_all();
399         enter_lazy_tlb(mm, current);
400         local_flush_tlb_all();
401
402         /*
403          * All kernel threads share the same mm context; grab a
404          * reference and switch to it.
405          */
406         cpu = smp_processor_id();
407         mmgrab(mm);
408         current->active_mm = mm;
409         cpumask_set_cpu(cpu, mm_cpumask(mm));
410
411         cpu_init();
412
413 #ifndef CONFIG_MMU
414         setup_vectors_base();
415 #endif
416         pr_debug("CPU%u: Booted secondary processor\n", cpu);
417
418         preempt_disable();
419         trace_hardirqs_off();
420
421         /*
422          * Give the platform a chance to do its own initialisation.
423          */
424         if (smp_ops.smp_secondary_init)
425                 smp_ops.smp_secondary_init(cpu);
426
427         notify_cpu_starting(cpu);
428
429         calibrate_delay();
430
431         smp_store_cpu_info(cpu);
432
433         /*
434          * OK, now it's safe to let the boot CPU continue.  Wait for
435          * the CPU migration code to notice that the CPU is online
436          * before we continue - which happens after __cpu_up returns.
437          */
438         set_cpu_online(cpu, true);
439
440         check_other_bugs();
441
442         complete(&cpu_running);
443
444         local_irq_enable();
445         local_fiq_enable();
446         local_abt_enable();
447
448         /*
449          * OK, it's off to the idle thread for us
450          */
451         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
452 }
453
454 void __init smp_cpus_done(unsigned int max_cpus)
455 {
456         int cpu;
457         unsigned long bogosum = 0;
458
459         for_each_online_cpu(cpu)
460                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
461
462         printk(KERN_INFO "SMP: Total of %d processors activated "
463                "(%lu.%02lu BogoMIPS).\n",
464                num_online_cpus(),
465                bogosum / (500000/HZ),
466                (bogosum / (5000/HZ)) % 100);
467
468         hyp_mode_check();
469 }
470
471 void __init smp_prepare_boot_cpu(void)
472 {
473         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
474 }
475
476 void __init smp_prepare_cpus(unsigned int max_cpus)
477 {
478         unsigned int ncores = num_possible_cpus();
479
480         init_cpu_topology();
481
482         smp_store_cpu_info(smp_processor_id());
483
484         /*
485          * are we trying to boot more cores than exist?
486          */
487         if (max_cpus > ncores)
488                 max_cpus = ncores;
489         if (ncores > 1 && max_cpus) {
490                 /*
491                  * Initialise the present map, which describes the set of CPUs
492                  * actually populated at the present time. A platform should
493                  * re-initialize the map in the platforms smp_prepare_cpus()
494                  * if present != possible (e.g. physical hotplug).
495                  */
496                 init_cpu_present(cpu_possible_mask);
497
498                 /*
499                  * Initialise the SCU if there are more than one CPU
500                  * and let them know where to start.
501                  */
502                 if (smp_ops.smp_prepare_cpus)
503                         smp_ops.smp_prepare_cpus(max_cpus);
504         }
505 }
506
507 static void (*__smp_cross_call)(const struct cpumask *, unsigned int);
508
509 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
510 {
511         if (!__smp_cross_call)
512                 __smp_cross_call = fn;
513 }
514
515 static const char *ipi_types[NR_IPI] __tracepoint_string = {
516 #define S(x,s)  [x] = s
517         S(IPI_WAKEUP, "CPU wakeup interrupts"),
518         S(IPI_TIMER, "Timer broadcast interrupts"),
519         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
520         S(IPI_CALL_FUNC, "Function call interrupts"),
521         S(IPI_CPU_STOP, "CPU stop interrupts"),
522         S(IPI_IRQ_WORK, "IRQ work interrupts"),
523         S(IPI_COMPLETION, "completion interrupts"),
524 };
525
526 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
527 {
528         trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
529         __smp_cross_call(target, ipinr);
530 }
531
532 void show_ipi_list(struct seq_file *p, int prec)
533 {
534         unsigned int cpu, i;
535
536         for (i = 0; i < NR_IPI; i++) {
537                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
538
539                 for_each_online_cpu(cpu)
540                         seq_printf(p, "%10u ",
541                                    __get_irq_stat(cpu, ipi_irqs[i]));
542
543                 seq_printf(p, " %s\n", ipi_types[i]);
544         }
545 }
546
547 u64 smp_irq_stat_cpu(unsigned int cpu)
548 {
549         u64 sum = 0;
550         int i;
551
552         for (i = 0; i < NR_IPI; i++)
553                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
554
555         return sum;
556 }
557
558 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
559 {
560         smp_cross_call(mask, IPI_CALL_FUNC);
561 }
562
563 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
564 {
565         smp_cross_call(mask, IPI_WAKEUP);
566 }
567
568 void arch_send_call_function_single_ipi(int cpu)
569 {
570         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
571 }
572
573 #ifdef CONFIG_IRQ_WORK
574 void arch_irq_work_raise(void)
575 {
576         if (arch_irq_work_has_interrupt())
577                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
578 }
579 #endif
580
581 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
582 void tick_broadcast(const struct cpumask *mask)
583 {
584         smp_cross_call(mask, IPI_TIMER);
585 }
586 #endif
587
588 static DEFINE_RAW_SPINLOCK(stop_lock);
589
590 /*
591  * ipi_cpu_stop - handle IPI from smp_send_stop()
592  */
593 static void ipi_cpu_stop(unsigned int cpu)
594 {
595         if (system_state <= SYSTEM_RUNNING) {
596                 raw_spin_lock(&stop_lock);
597                 pr_crit("CPU%u: stopping\n", cpu);
598                 dump_stack();
599                 raw_spin_unlock(&stop_lock);
600         }
601
602         set_cpu_online(cpu, false);
603
604         local_fiq_disable();
605         local_irq_disable();
606
607         while (1)
608                 cpu_relax();
609 }
610
611 static DEFINE_PER_CPU(struct completion *, cpu_completion);
612
613 int register_ipi_completion(struct completion *completion, int cpu)
614 {
615         per_cpu(cpu_completion, cpu) = completion;
616         return IPI_COMPLETION;
617 }
618
619 static void ipi_complete(unsigned int cpu)
620 {
621         complete(per_cpu(cpu_completion, cpu));
622 }
623
624 /*
625  * Main handler for inter-processor interrupts
626  */
627 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
628 {
629         handle_IPI(ipinr, regs);
630 }
631
632 void handle_IPI(int ipinr, struct pt_regs *regs)
633 {
634         unsigned int cpu = smp_processor_id();
635         struct pt_regs *old_regs = set_irq_regs(regs);
636
637         if ((unsigned)ipinr < NR_IPI) {
638                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
639                 __inc_irq_stat(cpu, ipi_irqs[ipinr]);
640         }
641
642         switch (ipinr) {
643         case IPI_WAKEUP:
644                 break;
645
646 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
647         case IPI_TIMER:
648                 irq_enter();
649                 tick_receive_broadcast();
650                 irq_exit();
651                 break;
652 #endif
653
654         case IPI_RESCHEDULE:
655                 scheduler_ipi();
656                 break;
657
658         case IPI_CALL_FUNC:
659                 irq_enter();
660                 generic_smp_call_function_interrupt();
661                 irq_exit();
662                 break;
663
664         case IPI_CPU_STOP:
665                 irq_enter();
666                 ipi_cpu_stop(cpu);
667                 irq_exit();
668                 break;
669
670 #ifdef CONFIG_IRQ_WORK
671         case IPI_IRQ_WORK:
672                 irq_enter();
673                 irq_work_run();
674                 irq_exit();
675                 break;
676 #endif
677
678         case IPI_COMPLETION:
679                 irq_enter();
680                 ipi_complete(cpu);
681                 irq_exit();
682                 break;
683
684         case IPI_CPU_BACKTRACE:
685                 printk_nmi_enter();
686                 irq_enter();
687                 nmi_cpu_backtrace(regs);
688                 irq_exit();
689                 printk_nmi_exit();
690                 break;
691
692         default:
693                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
694                         cpu, ipinr);
695                 break;
696         }
697
698         if ((unsigned)ipinr < NR_IPI)
699                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
700         set_irq_regs(old_regs);
701 }
702
703 void smp_send_reschedule(int cpu)
704 {
705         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
706 }
707
708 void smp_send_stop(void)
709 {
710         unsigned long timeout;
711         struct cpumask mask;
712
713         cpumask_copy(&mask, cpu_online_mask);
714         cpumask_clear_cpu(smp_processor_id(), &mask);
715         if (!cpumask_empty(&mask))
716                 smp_cross_call(&mask, IPI_CPU_STOP);
717
718         /* Wait up to one second for other CPUs to stop */
719         timeout = USEC_PER_SEC;
720         while (num_online_cpus() > 1 && timeout--)
721                 udelay(1);
722
723         if (num_online_cpus() > 1)
724                 pr_warn("SMP: failed to stop secondary CPUs\n");
725 }
726
727 /*
728  * not supported here
729  */
730 int setup_profiling_timer(unsigned int multiplier)
731 {
732         return -EINVAL;
733 }
734
735 #ifdef CONFIG_CPU_FREQ
736
737 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
738 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
739 static unsigned long global_l_p_j_ref;
740 static unsigned long global_l_p_j_ref_freq;
741
742 static int cpufreq_callback(struct notifier_block *nb,
743                                         unsigned long val, void *data)
744 {
745         struct cpufreq_freqs *freq = data;
746         int cpu = freq->cpu;
747
748         if (freq->flags & CPUFREQ_CONST_LOOPS)
749                 return NOTIFY_OK;
750
751         if (!per_cpu(l_p_j_ref, cpu)) {
752                 per_cpu(l_p_j_ref, cpu) =
753                         per_cpu(cpu_data, cpu).loops_per_jiffy;
754                 per_cpu(l_p_j_ref_freq, cpu) = freq->old;
755                 if (!global_l_p_j_ref) {
756                         global_l_p_j_ref = loops_per_jiffy;
757                         global_l_p_j_ref_freq = freq->old;
758                 }
759         }
760
761         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
762             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
763                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
764                                                 global_l_p_j_ref_freq,
765                                                 freq->new);
766                 per_cpu(cpu_data, cpu).loops_per_jiffy =
767                         cpufreq_scale(per_cpu(l_p_j_ref, cpu),
768                                         per_cpu(l_p_j_ref_freq, cpu),
769                                         freq->new);
770         }
771         return NOTIFY_OK;
772 }
773
774 static struct notifier_block cpufreq_notifier = {
775         .notifier_call  = cpufreq_callback,
776 };
777
778 static int __init register_cpufreq_notifier(void)
779 {
780         return cpufreq_register_notifier(&cpufreq_notifier,
781                                                 CPUFREQ_TRANSITION_NOTIFIER);
782 }
783 core_initcall(register_cpufreq_notifier);
784
785 #endif
786
787 static void raise_nmi(cpumask_t *mask)
788 {
789         smp_cross_call(mask, IPI_CPU_BACKTRACE);
790 }
791
792 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
793 {
794         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
795 }