Merge tag 'armsoc-dt' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
[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 enum ipi_msg_type {
66         IPI_WAKEUP,
67         IPI_TIMER,
68         IPI_RESCHEDULE,
69         IPI_CALL_FUNC,
70         IPI_CPU_STOP,
71         IPI_IRQ_WORK,
72         IPI_COMPLETION,
73         /*
74          * CPU_BACKTRACE is special and not included in NR_IPI
75          * or tracable with trace_ipi_*
76          */
77         IPI_CPU_BACKTRACE,
78         /*
79          * SGI8-15 can be reserved by secure firmware, and thus may
80          * not be usable by the kernel. Please keep the above limited
81          * to at most 8 entries.
82          */
83 };
84
85 static DECLARE_COMPLETION(cpu_running);
86
87 static struct smp_operations smp_ops __ro_after_init;
88
89 void __init smp_set_ops(const struct smp_operations *ops)
90 {
91         if (ops)
92                 smp_ops = *ops;
93 };
94
95 static unsigned long get_arch_pgd(pgd_t *pgd)
96 {
97 #ifdef CONFIG_ARM_LPAE
98         return __phys_to_pfn(virt_to_phys(pgd));
99 #else
100         return virt_to_phys(pgd);
101 #endif
102 }
103
104 #if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
105 static int secondary_biglittle_prepare(unsigned int cpu)
106 {
107         if (!cpu_vtable[cpu])
108                 cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL);
109
110         return cpu_vtable[cpu] ? 0 : -ENOMEM;
111 }
112
113 static void secondary_biglittle_init(void)
114 {
115         init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
116 }
117 #else
118 static int secondary_biglittle_prepare(unsigned int cpu)
119 {
120         return 0;
121 }
122
123 static void secondary_biglittle_init(void)
124 {
125 }
126 #endif
127
128 int __cpu_up(unsigned int cpu, struct task_struct *idle)
129 {
130         int ret;
131
132         if (!smp_ops.smp_boot_secondary)
133                 return -ENOSYS;
134
135         ret = secondary_biglittle_prepare(cpu);
136         if (ret)
137                 return ret;
138
139         /*
140          * We need to tell the secondary core where to find
141          * its stack and the page tables.
142          */
143         secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
144 #ifdef CONFIG_ARM_MPU
145         secondary_data.mpu_rgn_info = &mpu_rgn_info;
146 #endif
147
148 #ifdef CONFIG_MMU
149         secondary_data.pgdir = virt_to_phys(idmap_pgd);
150         secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
151 #endif
152         sync_cache_w(&secondary_data);
153
154         /*
155          * Now bring the CPU into our world.
156          */
157         ret = smp_ops.smp_boot_secondary(cpu, idle);
158         if (ret == 0) {
159                 /*
160                  * CPU was successfully started, wait for it
161                  * to come online or time out.
162                  */
163                 wait_for_completion_timeout(&cpu_running,
164                                                  msecs_to_jiffies(1000));
165
166                 if (!cpu_online(cpu)) {
167                         pr_crit("CPU%u: failed to come online\n", cpu);
168                         ret = -EIO;
169                 }
170         } else {
171                 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
172         }
173
174
175         memset(&secondary_data, 0, sizeof(secondary_data));
176         return ret;
177 }
178
179 /* platform specific SMP operations */
180 void __init smp_init_cpus(void)
181 {
182         if (smp_ops.smp_init_cpus)
183                 smp_ops.smp_init_cpus();
184 }
185
186 int platform_can_secondary_boot(void)
187 {
188         return !!smp_ops.smp_boot_secondary;
189 }
190
191 int platform_can_cpu_hotplug(void)
192 {
193 #ifdef CONFIG_HOTPLUG_CPU
194         if (smp_ops.cpu_kill)
195                 return 1;
196 #endif
197
198         return 0;
199 }
200
201 #ifdef CONFIG_HOTPLUG_CPU
202 static int platform_cpu_kill(unsigned int cpu)
203 {
204         if (smp_ops.cpu_kill)
205                 return smp_ops.cpu_kill(cpu);
206         return 1;
207 }
208
209 static int platform_cpu_disable(unsigned int cpu)
210 {
211         if (smp_ops.cpu_disable)
212                 return smp_ops.cpu_disable(cpu);
213
214         return 0;
215 }
216
217 int platform_can_hotplug_cpu(unsigned int cpu)
218 {
219         /* cpu_die must be specified to support hotplug */
220         if (!smp_ops.cpu_die)
221                 return 0;
222
223         if (smp_ops.cpu_can_disable)
224                 return smp_ops.cpu_can_disable(cpu);
225
226         /*
227          * By default, allow disabling all CPUs except the first one,
228          * since this is special on a lot of platforms, e.g. because
229          * of clock tick interrupts.
230          */
231         return cpu != 0;
232 }
233
234 /*
235  * __cpu_disable runs on the processor to be shutdown.
236  */
237 int __cpu_disable(void)
238 {
239         unsigned int cpu = smp_processor_id();
240         int ret;
241
242         ret = platform_cpu_disable(cpu);
243         if (ret)
244                 return ret;
245
246         /*
247          * Take this CPU offline.  Once we clear this, we can't return,
248          * and we must not schedule until we're ready to give up the cpu.
249          */
250         set_cpu_online(cpu, false);
251
252         /*
253          * OK - migrate IRQs away from this CPU
254          */
255         irq_migrate_all_off_this_cpu();
256
257         /*
258          * Flush user cache and TLB mappings, and then remove this CPU
259          * from the vm mask set of all processes.
260          *
261          * Caches are flushed to the Level of Unification Inner Shareable
262          * to write-back dirty lines to unified caches shared by all CPUs.
263          */
264         flush_cache_louis();
265         local_flush_tlb_all();
266
267         return 0;
268 }
269
270 static DECLARE_COMPLETION(cpu_died);
271
272 /*
273  * called on the thread which is asking for a CPU to be shutdown -
274  * waits until shutdown has completed, or it is timed out.
275  */
276 void __cpu_die(unsigned int cpu)
277 {
278         if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
279                 pr_err("CPU%u: cpu didn't die\n", cpu);
280                 return;
281         }
282         pr_debug("CPU%u: shutdown\n", cpu);
283
284         clear_tasks_mm_cpumask(cpu);
285         /*
286          * platform_cpu_kill() is generally expected to do the powering off
287          * and/or cutting of clocks to the dying CPU.  Optionally, this may
288          * be done by the CPU which is dying in preference to supporting
289          * this call, but that means there is _no_ synchronisation between
290          * the requesting CPU and the dying CPU actually losing power.
291          */
292         if (!platform_cpu_kill(cpu))
293                 pr_err("CPU%u: unable to kill\n", cpu);
294 }
295
296 /*
297  * Called from the idle thread for the CPU which has been shutdown.
298  *
299  * Note that we disable IRQs here, but do not re-enable them
300  * before returning to the caller. This is also the behaviour
301  * of the other hotplug-cpu capable cores, so presumably coming
302  * out of idle fixes this.
303  */
304 void arch_cpu_idle_dead(void)
305 {
306         unsigned int cpu = smp_processor_id();
307
308         idle_task_exit();
309
310         local_irq_disable();
311
312         /*
313          * Flush the data out of the L1 cache for this CPU.  This must be
314          * before the completion to ensure that data is safely written out
315          * before platform_cpu_kill() gets called - which may disable
316          * *this* CPU and power down its cache.
317          */
318         flush_cache_louis();
319
320         /*
321          * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
322          * this returns, power and/or clocks can be removed at any point
323          * from this CPU and its cache by platform_cpu_kill().
324          */
325         complete(&cpu_died);
326
327         /*
328          * Ensure that the cache lines associated with that completion are
329          * written out.  This covers the case where _this_ CPU is doing the
330          * powering down, to ensure that the completion is visible to the
331          * CPU waiting for this one.
332          */
333         flush_cache_louis();
334
335         /*
336          * The actual CPU shutdown procedure is at least platform (if not
337          * CPU) specific.  This may remove power, or it may simply spin.
338          *
339          * Platforms are generally expected *NOT* to return from this call,
340          * although there are some which do because they have no way to
341          * power down the CPU.  These platforms are the _only_ reason we
342          * have a return path which uses the fragment of assembly below.
343          *
344          * The return path should not be used for platforms which can
345          * power off the CPU.
346          */
347         if (smp_ops.cpu_die)
348                 smp_ops.cpu_die(cpu);
349
350         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
351                 cpu);
352
353         /*
354          * Do not return to the idle loop - jump back to the secondary
355          * cpu initialisation.  There's some initialisation which needs
356          * to be repeated to undo the effects of taking the CPU offline.
357          */
358         __asm__("mov    sp, %0\n"
359         "       mov     fp, #0\n"
360         "       b       secondary_start_kernel"
361                 :
362                 : "r" (task_stack_page(current) + THREAD_SIZE - 8));
363 }
364 #endif /* CONFIG_HOTPLUG_CPU */
365
366 /*
367  * Called by both boot and secondaries to move global data into
368  * per-processor storage.
369  */
370 static void smp_store_cpu_info(unsigned int cpuid)
371 {
372         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
373
374         cpu_info->loops_per_jiffy = loops_per_jiffy;
375         cpu_info->cpuid = read_cpuid_id();
376
377         store_cpu_topology(cpuid);
378 }
379
380 /*
381  * This is the secondary CPU boot entry.  We're using this CPUs
382  * idle thread stack, but a set of temporary page tables.
383  */
384 asmlinkage void secondary_start_kernel(void)
385 {
386         struct mm_struct *mm = &init_mm;
387         unsigned int cpu;
388
389         secondary_biglittle_init();
390
391         /*
392          * The identity mapping is uncached (strongly ordered), so
393          * switch away from it before attempting any exclusive accesses.
394          */
395         cpu_switch_mm(mm->pgd, mm);
396         local_flush_bp_all();
397         enter_lazy_tlb(mm, current);
398         local_flush_tlb_all();
399
400         /*
401          * All kernel threads share the same mm context; grab a
402          * reference and switch to it.
403          */
404         cpu = smp_processor_id();
405         mmgrab(mm);
406         current->active_mm = mm;
407         cpumask_set_cpu(cpu, mm_cpumask(mm));
408
409         cpu_init();
410
411 #ifndef CONFIG_MMU
412         setup_vectors_base();
413 #endif
414         pr_debug("CPU%u: Booted secondary processor\n", cpu);
415
416         preempt_disable();
417         trace_hardirqs_off();
418
419         /*
420          * Give the platform a chance to do its own initialisation.
421          */
422         if (smp_ops.smp_secondary_init)
423                 smp_ops.smp_secondary_init(cpu);
424
425         notify_cpu_starting(cpu);
426
427         calibrate_delay();
428
429         smp_store_cpu_info(cpu);
430
431         /*
432          * OK, now it's safe to let the boot CPU continue.  Wait for
433          * the CPU migration code to notice that the CPU is online
434          * before we continue - which happens after __cpu_up returns.
435          */
436         set_cpu_online(cpu, true);
437
438         check_other_bugs();
439
440         complete(&cpu_running);
441
442         local_irq_enable();
443         local_fiq_enable();
444         local_abt_enable();
445
446         /*
447          * OK, it's off to the idle thread for us
448          */
449         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
450 }
451
452 void __init smp_cpus_done(unsigned int max_cpus)
453 {
454         int cpu;
455         unsigned long bogosum = 0;
456
457         for_each_online_cpu(cpu)
458                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
459
460         printk(KERN_INFO "SMP: Total of %d processors activated "
461                "(%lu.%02lu BogoMIPS).\n",
462                num_online_cpus(),
463                bogosum / (500000/HZ),
464                (bogosum / (5000/HZ)) % 100);
465
466         hyp_mode_check();
467 }
468
469 void __init smp_prepare_boot_cpu(void)
470 {
471         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
472 }
473
474 void __init smp_prepare_cpus(unsigned int max_cpus)
475 {
476         unsigned int ncores = num_possible_cpus();
477
478         init_cpu_topology();
479
480         smp_store_cpu_info(smp_processor_id());
481
482         /*
483          * are we trying to boot more cores than exist?
484          */
485         if (max_cpus > ncores)
486                 max_cpus = ncores;
487         if (ncores > 1 && max_cpus) {
488                 /*
489                  * Initialise the present map, which describes the set of CPUs
490                  * actually populated at the present time. A platform should
491                  * re-initialize the map in the platforms smp_prepare_cpus()
492                  * if present != possible (e.g. physical hotplug).
493                  */
494                 init_cpu_present(cpu_possible_mask);
495
496                 /*
497                  * Initialise the SCU if there are more than one CPU
498                  * and let them know where to start.
499                  */
500                 if (smp_ops.smp_prepare_cpus)
501                         smp_ops.smp_prepare_cpus(max_cpus);
502         }
503 }
504
505 static void (*__smp_cross_call)(const struct cpumask *, unsigned int);
506
507 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
508 {
509         if (!__smp_cross_call)
510                 __smp_cross_call = fn;
511 }
512
513 static const char *ipi_types[NR_IPI] __tracepoint_string = {
514 #define S(x,s)  [x] = s
515         S(IPI_WAKEUP, "CPU wakeup interrupts"),
516         S(IPI_TIMER, "Timer broadcast interrupts"),
517         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
518         S(IPI_CALL_FUNC, "Function call interrupts"),
519         S(IPI_CPU_STOP, "CPU stop interrupts"),
520         S(IPI_IRQ_WORK, "IRQ work interrupts"),
521         S(IPI_COMPLETION, "completion interrupts"),
522 };
523
524 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
525 {
526         trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
527         __smp_cross_call(target, ipinr);
528 }
529
530 void show_ipi_list(struct seq_file *p, int prec)
531 {
532         unsigned int cpu, i;
533
534         for (i = 0; i < NR_IPI; i++) {
535                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
536
537                 for_each_online_cpu(cpu)
538                         seq_printf(p, "%10u ",
539                                    __get_irq_stat(cpu, ipi_irqs[i]));
540
541                 seq_printf(p, " %s\n", ipi_types[i]);
542         }
543 }
544
545 u64 smp_irq_stat_cpu(unsigned int cpu)
546 {
547         u64 sum = 0;
548         int i;
549
550         for (i = 0; i < NR_IPI; i++)
551                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
552
553         return sum;
554 }
555
556 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
557 {
558         smp_cross_call(mask, IPI_CALL_FUNC);
559 }
560
561 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
562 {
563         smp_cross_call(mask, IPI_WAKEUP);
564 }
565
566 void arch_send_call_function_single_ipi(int cpu)
567 {
568         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
569 }
570
571 #ifdef CONFIG_IRQ_WORK
572 void arch_irq_work_raise(void)
573 {
574         if (arch_irq_work_has_interrupt())
575                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
576 }
577 #endif
578
579 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
580 void tick_broadcast(const struct cpumask *mask)
581 {
582         smp_cross_call(mask, IPI_TIMER);
583 }
584 #endif
585
586 static DEFINE_RAW_SPINLOCK(stop_lock);
587
588 /*
589  * ipi_cpu_stop - handle IPI from smp_send_stop()
590  */
591 static void ipi_cpu_stop(unsigned int cpu)
592 {
593         if (system_state <= SYSTEM_RUNNING) {
594                 raw_spin_lock(&stop_lock);
595                 pr_crit("CPU%u: stopping\n", cpu);
596                 dump_stack();
597                 raw_spin_unlock(&stop_lock);
598         }
599
600         set_cpu_online(cpu, false);
601
602         local_fiq_disable();
603         local_irq_disable();
604
605         while (1) {
606                 cpu_relax();
607                 wfe();
608         }
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 /* In case panic() and panic() called at the same time on CPU1 and CPU2,
728  * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
729  * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
730  * kdump fails. So split out the panic_smp_self_stop() and add
731  * set_cpu_online(smp_processor_id(), false).
732  */
733 void panic_smp_self_stop(void)
734 {
735         pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
736                  smp_processor_id());
737         set_cpu_online(smp_processor_id(), false);
738         while (1)
739                 cpu_relax();
740 }
741
742 /*
743  * not supported here
744  */
745 int setup_profiling_timer(unsigned int multiplier)
746 {
747         return -EINVAL;
748 }
749
750 #ifdef CONFIG_CPU_FREQ
751
752 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
753 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
754 static unsigned long global_l_p_j_ref;
755 static unsigned long global_l_p_j_ref_freq;
756
757 static int cpufreq_callback(struct notifier_block *nb,
758                                         unsigned long val, void *data)
759 {
760         struct cpufreq_freqs *freq = data;
761         struct cpumask *cpus = freq->policy->cpus;
762         int cpu, first = cpumask_first(cpus);
763         unsigned int lpj;
764
765         if (freq->flags & CPUFREQ_CONST_LOOPS)
766                 return NOTIFY_OK;
767
768         if (!per_cpu(l_p_j_ref, first)) {
769                 for_each_cpu(cpu, cpus) {
770                         per_cpu(l_p_j_ref, cpu) =
771                                 per_cpu(cpu_data, cpu).loops_per_jiffy;
772                         per_cpu(l_p_j_ref_freq, cpu) = freq->old;
773                 }
774
775                 if (!global_l_p_j_ref) {
776                         global_l_p_j_ref = loops_per_jiffy;
777                         global_l_p_j_ref_freq = freq->old;
778                 }
779         }
780
781         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
782             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
783                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
784                                                 global_l_p_j_ref_freq,
785                                                 freq->new);
786
787                 lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
788                                     per_cpu(l_p_j_ref_freq, first), freq->new);
789                 for_each_cpu(cpu, cpus)
790                         per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
791         }
792         return NOTIFY_OK;
793 }
794
795 static struct notifier_block cpufreq_notifier = {
796         .notifier_call  = cpufreq_callback,
797 };
798
799 static int __init register_cpufreq_notifier(void)
800 {
801         return cpufreq_register_notifier(&cpufreq_notifier,
802                                                 CPUFREQ_TRANSITION_NOTIFIER);
803 }
804 core_initcall(register_cpufreq_notifier);
805
806 #endif
807
808 static void raise_nmi(cpumask_t *mask)
809 {
810         __smp_cross_call(mask, IPI_CPU_BACKTRACE);
811 }
812
813 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
814 {
815         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
816 }