xref: /openbmc/linux/arch/arm/kernel/smp.c (revision ccc319dc)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/arch/arm/kernel/smp.c
4  *
5  *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
6  */
7 #include <linux/module.h>
8 #include <linux/delay.h>
9 #include <linux/init.h>
10 #include <linux/spinlock.h>
11 #include <linux/sched/mm.h>
12 #include <linux/sched/hotplug.h>
13 #include <linux/sched/task_stack.h>
14 #include <linux/interrupt.h>
15 #include <linux/cache.h>
16 #include <linux/profile.h>
17 #include <linux/errno.h>
18 #include <linux/mm.h>
19 #include <linux/err.h>
20 #include <linux/cpu.h>
21 #include <linux/seq_file.h>
22 #include <linux/irq.h>
23 #include <linux/nmi.h>
24 #include <linux/percpu.h>
25 #include <linux/clockchips.h>
26 #include <linux/completion.h>
27 #include <linux/cpufreq.h>
28 #include <linux/irq_work.h>
29 #include <linux/kernel_stat.h>
30 
31 #include <linux/atomic.h>
32 #include <asm/bugs.h>
33 #include <asm/smp.h>
34 #include <asm/cacheflush.h>
35 #include <asm/cpu.h>
36 #include <asm/cputype.h>
37 #include <asm/exception.h>
38 #include <asm/idmap.h>
39 #include <asm/topology.h>
40 #include <asm/mmu_context.h>
41 #include <asm/procinfo.h>
42 #include <asm/processor.h>
43 #include <asm/sections.h>
44 #include <asm/tlbflush.h>
45 #include <asm/ptrace.h>
46 #include <asm/smp_plat.h>
47 #include <asm/virt.h>
48 #include <asm/mach/arch.h>
49 #include <asm/mpu.h>
50 
51 #define CREATE_TRACE_POINTS
52 #include <trace/events/ipi.h>
53 
54 /*
55  * as from 2.5, kernels no longer have an init_tasks structure
56  * so we need some other way of telling a new secondary core
57  * where to place its SVC stack
58  */
59 struct secondary_data secondary_data;
60 
61 enum ipi_msg_type {
62 	IPI_WAKEUP,
63 	IPI_TIMER,
64 	IPI_RESCHEDULE,
65 	IPI_CALL_FUNC,
66 	IPI_CPU_STOP,
67 	IPI_IRQ_WORK,
68 	IPI_COMPLETION,
69 	NR_IPI,
70 	/*
71 	 * CPU_BACKTRACE is special and not included in NR_IPI
72 	 * or tracable with trace_ipi_*
73 	 */
74 	IPI_CPU_BACKTRACE = NR_IPI,
75 	/*
76 	 * SGI8-15 can be reserved by secure firmware, and thus may
77 	 * not be usable by the kernel. Please keep the above limited
78 	 * to at most 8 entries.
79 	 */
80 	MAX_IPI
81 };
82 
83 static int ipi_irq_base __read_mostly;
84 static int nr_ipi __read_mostly = NR_IPI;
85 static struct irq_desc *ipi_desc[MAX_IPI] __read_mostly;
86 
87 static void ipi_setup(int cpu);
88 
89 static DECLARE_COMPLETION(cpu_running);
90 
91 static struct smp_operations smp_ops __ro_after_init;
92 
93 void __init smp_set_ops(const struct smp_operations *ops)
94 {
95 	if (ops)
96 		smp_ops = *ops;
97 };
98 
99 static unsigned long get_arch_pgd(pgd_t *pgd)
100 {
101 #ifdef CONFIG_ARM_LPAE
102 	return __phys_to_pfn(virt_to_phys(pgd));
103 #else
104 	return virt_to_phys(pgd);
105 #endif
106 }
107 
108 #if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
109 static int secondary_biglittle_prepare(unsigned int cpu)
110 {
111 	if (!cpu_vtable[cpu])
112 		cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL);
113 
114 	return cpu_vtable[cpu] ? 0 : -ENOMEM;
115 }
116 
117 static void secondary_biglittle_init(void)
118 {
119 	init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
120 }
121 #else
122 static int secondary_biglittle_prepare(unsigned int cpu)
123 {
124 	return 0;
125 }
126 
127 static void secondary_biglittle_init(void)
128 {
129 }
130 #endif
131 
132 int __cpu_up(unsigned int cpu, struct task_struct *idle)
133 {
134 	int ret;
135 
136 	if (!smp_ops.smp_boot_secondary)
137 		return -ENOSYS;
138 
139 	ret = secondary_biglittle_prepare(cpu);
140 	if (ret)
141 		return ret;
142 
143 	/*
144 	 * We need to tell the secondary core where to find
145 	 * its stack and the page tables.
146 	 */
147 	secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
148 #ifdef CONFIG_ARM_MPU
149 	secondary_data.mpu_rgn_info = &mpu_rgn_info;
150 #endif
151 
152 #ifdef CONFIG_MMU
153 	secondary_data.pgdir = virt_to_phys(idmap_pgd);
154 	secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
155 #endif
156 	secondary_data.task = idle;
157 	sync_cache_w(&secondary_data);
158 
159 	/*
160 	 * Now bring the CPU into our world.
161 	 */
162 	ret = smp_ops.smp_boot_secondary(cpu, idle);
163 	if (ret == 0) {
164 		/*
165 		 * CPU was successfully started, wait for it
166 		 * to come online or time out.
167 		 */
168 		wait_for_completion_timeout(&cpu_running,
169 						 msecs_to_jiffies(1000));
170 
171 		if (!cpu_online(cpu)) {
172 			pr_crit("CPU%u: failed to come online\n", cpu);
173 			ret = -EIO;
174 		}
175 	} else {
176 		pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
177 	}
178 
179 
180 	memset(&secondary_data, 0, sizeof(secondary_data));
181 	return ret;
182 }
183 
184 /* platform specific SMP operations */
185 void __init smp_init_cpus(void)
186 {
187 	if (smp_ops.smp_init_cpus)
188 		smp_ops.smp_init_cpus();
189 }
190 
191 int platform_can_secondary_boot(void)
192 {
193 	return !!smp_ops.smp_boot_secondary;
194 }
195 
196 int platform_can_cpu_hotplug(void)
197 {
198 #ifdef CONFIG_HOTPLUG_CPU
199 	if (smp_ops.cpu_kill)
200 		return 1;
201 #endif
202 
203 	return 0;
204 }
205 
206 #ifdef CONFIG_HOTPLUG_CPU
207 static int platform_cpu_kill(unsigned int cpu)
208 {
209 	if (smp_ops.cpu_kill)
210 		return smp_ops.cpu_kill(cpu);
211 	return 1;
212 }
213 
214 static int platform_cpu_disable(unsigned int cpu)
215 {
216 	if (smp_ops.cpu_disable)
217 		return smp_ops.cpu_disable(cpu);
218 
219 	return 0;
220 }
221 
222 int platform_can_hotplug_cpu(unsigned int cpu)
223 {
224 	/* cpu_die must be specified to support hotplug */
225 	if (!smp_ops.cpu_die)
226 		return 0;
227 
228 	if (smp_ops.cpu_can_disable)
229 		return smp_ops.cpu_can_disable(cpu);
230 
231 	/*
232 	 * By default, allow disabling all CPUs except the first one,
233 	 * since this is special on a lot of platforms, e.g. because
234 	 * of clock tick interrupts.
235 	 */
236 	return cpu != 0;
237 }
238 
239 static void ipi_teardown(int cpu)
240 {
241 	int i;
242 
243 	if (WARN_ON_ONCE(!ipi_irq_base))
244 		return;
245 
246 	for (i = 0; i < nr_ipi; i++)
247 		disable_percpu_irq(ipi_irq_base + i);
248 }
249 
250 /*
251  * __cpu_disable runs on the processor to be shutdown.
252  */
253 int __cpu_disable(void)
254 {
255 	unsigned int cpu = smp_processor_id();
256 	int ret;
257 
258 	ret = platform_cpu_disable(cpu);
259 	if (ret)
260 		return ret;
261 
262 #ifdef CONFIG_GENERIC_ARCH_TOPOLOGY
263 	remove_cpu_topology(cpu);
264 #endif
265 
266 	/*
267 	 * Take this CPU offline.  Once we clear this, we can't return,
268 	 * and we must not schedule until we're ready to give up the cpu.
269 	 */
270 	set_cpu_online(cpu, false);
271 	ipi_teardown(cpu);
272 
273 	/*
274 	 * OK - migrate IRQs away from this CPU
275 	 */
276 	irq_migrate_all_off_this_cpu();
277 
278 	/*
279 	 * Flush user cache and TLB mappings, and then remove this CPU
280 	 * from the vm mask set of all processes.
281 	 *
282 	 * Caches are flushed to the Level of Unification Inner Shareable
283 	 * to write-back dirty lines to unified caches shared by all CPUs.
284 	 */
285 	flush_cache_louis();
286 	local_flush_tlb_all();
287 
288 	return 0;
289 }
290 
291 /*
292  * called on the thread which is asking for a CPU to be shutdown -
293  * waits until shutdown has completed, or it is timed out.
294  */
295 void __cpu_die(unsigned int cpu)
296 {
297 	if (!cpu_wait_death(cpu, 5)) {
298 		pr_err("CPU%u: cpu didn't die\n", cpu);
299 		return;
300 	}
301 	pr_debug("CPU%u: shutdown\n", cpu);
302 
303 	clear_tasks_mm_cpumask(cpu);
304 	/*
305 	 * platform_cpu_kill() is generally expected to do the powering off
306 	 * and/or cutting of clocks to the dying CPU.  Optionally, this may
307 	 * be done by the CPU which is dying in preference to supporting
308 	 * this call, but that means there is _no_ synchronisation between
309 	 * the requesting CPU and the dying CPU actually losing power.
310 	 */
311 	if (!platform_cpu_kill(cpu))
312 		pr_err("CPU%u: unable to kill\n", cpu);
313 }
314 
315 /*
316  * Called from the idle thread for the CPU which has been shutdown.
317  *
318  * Note that we disable IRQs here, but do not re-enable them
319  * before returning to the caller. This is also the behaviour
320  * of the other hotplug-cpu capable cores, so presumably coming
321  * out of idle fixes this.
322  */
323 void arch_cpu_idle_dead(void)
324 {
325 	unsigned int cpu = smp_processor_id();
326 
327 	idle_task_exit();
328 
329 	local_irq_disable();
330 
331 	/*
332 	 * Flush the data out of the L1 cache for this CPU.  This must be
333 	 * before the completion to ensure that data is safely written out
334 	 * before platform_cpu_kill() gets called - which may disable
335 	 * *this* CPU and power down its cache.
336 	 */
337 	flush_cache_louis();
338 
339 	/*
340 	 * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
341 	 * this returns, power and/or clocks can be removed at any point
342 	 * from this CPU and its cache by platform_cpu_kill().
343 	 */
344 	(void)cpu_report_death();
345 
346 	/*
347 	 * Ensure that the cache lines associated with that completion are
348 	 * written out.  This covers the case where _this_ CPU is doing the
349 	 * powering down, to ensure that the completion is visible to the
350 	 * CPU waiting for this one.
351 	 */
352 	flush_cache_louis();
353 
354 	/*
355 	 * The actual CPU shutdown procedure is at least platform (if not
356 	 * CPU) specific.  This may remove power, or it may simply spin.
357 	 *
358 	 * Platforms are generally expected *NOT* to return from this call,
359 	 * although there are some which do because they have no way to
360 	 * power down the CPU.  These platforms are the _only_ reason we
361 	 * have a return path which uses the fragment of assembly below.
362 	 *
363 	 * The return path should not be used for platforms which can
364 	 * power off the CPU.
365 	 */
366 	if (smp_ops.cpu_die)
367 		smp_ops.cpu_die(cpu);
368 
369 	pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
370 		cpu);
371 
372 	/*
373 	 * Do not return to the idle loop - jump back to the secondary
374 	 * cpu initialisation.  There's some initialisation which needs
375 	 * to be repeated to undo the effects of taking the CPU offline.
376 	 */
377 	__asm__("mov	sp, %0\n"
378 	"	mov	fp, #0\n"
379 	"	mov	r0, %1\n"
380 	"	b	secondary_start_kernel"
381 		:
382 		: "r" (task_stack_page(current) + THREAD_SIZE - 8),
383 		  "r" (current)
384 		: "r0");
385 }
386 #endif /* CONFIG_HOTPLUG_CPU */
387 
388 /*
389  * Called by both boot and secondaries to move global data into
390  * per-processor storage.
391  */
392 static void smp_store_cpu_info(unsigned int cpuid)
393 {
394 	struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
395 
396 	cpu_info->loops_per_jiffy = loops_per_jiffy;
397 	cpu_info->cpuid = read_cpuid_id();
398 
399 	store_cpu_topology(cpuid);
400 	check_cpu_icache_size(cpuid);
401 }
402 
403 static void set_current(struct task_struct *cur)
404 {
405 	/* Set TPIDRURO */
406 	asm("mcr p15, 0, %0, c13, c0, 3" :: "r"(cur) : "memory");
407 }
408 
409 /*
410  * This is the secondary CPU boot entry.  We're using this CPUs
411  * idle thread stack, but a set of temporary page tables.
412  */
413 asmlinkage void secondary_start_kernel(struct task_struct *task)
414 {
415 	struct mm_struct *mm = &init_mm;
416 	unsigned int cpu;
417 
418 	set_current(task);
419 
420 	secondary_biglittle_init();
421 
422 	/*
423 	 * The identity mapping is uncached (strongly ordered), so
424 	 * switch away from it before attempting any exclusive accesses.
425 	 */
426 	cpu_switch_mm(mm->pgd, mm);
427 	local_flush_bp_all();
428 	enter_lazy_tlb(mm, current);
429 	local_flush_tlb_all();
430 
431 	/*
432 	 * All kernel threads share the same mm context; grab a
433 	 * reference and switch to it.
434 	 */
435 	cpu = smp_processor_id();
436 	mmgrab(mm);
437 	current->active_mm = mm;
438 	cpumask_set_cpu(cpu, mm_cpumask(mm));
439 
440 	cpu_init();
441 
442 #ifndef CONFIG_MMU
443 	setup_vectors_base();
444 #endif
445 	pr_debug("CPU%u: Booted secondary processor\n", cpu);
446 
447 	trace_hardirqs_off();
448 
449 	/*
450 	 * Give the platform a chance to do its own initialisation.
451 	 */
452 	if (smp_ops.smp_secondary_init)
453 		smp_ops.smp_secondary_init(cpu);
454 
455 	notify_cpu_starting(cpu);
456 
457 	ipi_setup(cpu);
458 
459 	calibrate_delay();
460 
461 	smp_store_cpu_info(cpu);
462 
463 	/*
464 	 * OK, now it's safe to let the boot CPU continue.  Wait for
465 	 * the CPU migration code to notice that the CPU is online
466 	 * before we continue - which happens after __cpu_up returns.
467 	 */
468 	set_cpu_online(cpu, true);
469 
470 	check_other_bugs();
471 
472 	complete(&cpu_running);
473 
474 	local_irq_enable();
475 	local_fiq_enable();
476 	local_abt_enable();
477 
478 	/*
479 	 * OK, it's off to the idle thread for us
480 	 */
481 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
482 }
483 
484 void __init smp_cpus_done(unsigned int max_cpus)
485 {
486 	int cpu;
487 	unsigned long bogosum = 0;
488 
489 	for_each_online_cpu(cpu)
490 		bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
491 
492 	printk(KERN_INFO "SMP: Total of %d processors activated "
493 	       "(%lu.%02lu BogoMIPS).\n",
494 	       num_online_cpus(),
495 	       bogosum / (500000/HZ),
496 	       (bogosum / (5000/HZ)) % 100);
497 
498 	hyp_mode_check();
499 }
500 
501 void __init smp_prepare_boot_cpu(void)
502 {
503 	set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
504 }
505 
506 void __init smp_prepare_cpus(unsigned int max_cpus)
507 {
508 	unsigned int ncores = num_possible_cpus();
509 
510 	init_cpu_topology();
511 
512 	smp_store_cpu_info(smp_processor_id());
513 
514 	/*
515 	 * are we trying to boot more cores than exist?
516 	 */
517 	if (max_cpus > ncores)
518 		max_cpus = ncores;
519 	if (ncores > 1 && max_cpus) {
520 		/*
521 		 * Initialise the present map, which describes the set of CPUs
522 		 * actually populated at the present time. A platform should
523 		 * re-initialize the map in the platforms smp_prepare_cpus()
524 		 * if present != possible (e.g. physical hotplug).
525 		 */
526 		init_cpu_present(cpu_possible_mask);
527 
528 		/*
529 		 * Initialise the SCU if there are more than one CPU
530 		 * and let them know where to start.
531 		 */
532 		if (smp_ops.smp_prepare_cpus)
533 			smp_ops.smp_prepare_cpus(max_cpus);
534 	}
535 }
536 
537 static const char *ipi_types[NR_IPI] __tracepoint_string = {
538 	[IPI_WAKEUP]		= "CPU wakeup interrupts",
539 	[IPI_TIMER]		= "Timer broadcast interrupts",
540 	[IPI_RESCHEDULE]	= "Rescheduling interrupts",
541 	[IPI_CALL_FUNC]		= "Function call interrupts",
542 	[IPI_CPU_STOP]		= "CPU stop interrupts",
543 	[IPI_IRQ_WORK]		= "IRQ work interrupts",
544 	[IPI_COMPLETION]	= "completion interrupts",
545 };
546 
547 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr);
548 
549 void show_ipi_list(struct seq_file *p, int prec)
550 {
551 	unsigned int cpu, i;
552 
553 	for (i = 0; i < NR_IPI; i++) {
554 		if (!ipi_desc[i])
555 			continue;
556 
557 		seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
558 
559 		for_each_online_cpu(cpu)
560 			seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
561 
562 		seq_printf(p, " %s\n", ipi_types[i]);
563 	}
564 }
565 
566 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
567 {
568 	smp_cross_call(mask, IPI_CALL_FUNC);
569 }
570 
571 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
572 {
573 	smp_cross_call(mask, IPI_WAKEUP);
574 }
575 
576 void arch_send_call_function_single_ipi(int cpu)
577 {
578 	smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
579 }
580 
581 #ifdef CONFIG_IRQ_WORK
582 void arch_irq_work_raise(void)
583 {
584 	if (arch_irq_work_has_interrupt())
585 		smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
586 }
587 #endif
588 
589 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
590 void tick_broadcast(const struct cpumask *mask)
591 {
592 	smp_cross_call(mask, IPI_TIMER);
593 }
594 #endif
595 
596 static DEFINE_RAW_SPINLOCK(stop_lock);
597 
598 /*
599  * ipi_cpu_stop - handle IPI from smp_send_stop()
600  */
601 static void ipi_cpu_stop(unsigned int cpu)
602 {
603 	if (system_state <= SYSTEM_RUNNING) {
604 		raw_spin_lock(&stop_lock);
605 		pr_crit("CPU%u: stopping\n", cpu);
606 		dump_stack();
607 		raw_spin_unlock(&stop_lock);
608 	}
609 
610 	set_cpu_online(cpu, false);
611 
612 	local_fiq_disable();
613 	local_irq_disable();
614 
615 	while (1) {
616 		cpu_relax();
617 		wfe();
618 	}
619 }
620 
621 static DEFINE_PER_CPU(struct completion *, cpu_completion);
622 
623 int register_ipi_completion(struct completion *completion, int cpu)
624 {
625 	per_cpu(cpu_completion, cpu) = completion;
626 	return IPI_COMPLETION;
627 }
628 
629 static void ipi_complete(unsigned int cpu)
630 {
631 	complete(per_cpu(cpu_completion, cpu));
632 }
633 
634 /*
635  * Main handler for inter-processor interrupts
636  */
637 static void do_handle_IPI(int ipinr)
638 {
639 	unsigned int cpu = smp_processor_id();
640 
641 	if ((unsigned)ipinr < NR_IPI)
642 		trace_ipi_entry_rcuidle(ipi_types[ipinr]);
643 
644 	switch (ipinr) {
645 	case IPI_WAKEUP:
646 		break;
647 
648 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
649 	case IPI_TIMER:
650 		tick_receive_broadcast();
651 		break;
652 #endif
653 
654 	case IPI_RESCHEDULE:
655 		scheduler_ipi();
656 		break;
657 
658 	case IPI_CALL_FUNC:
659 		generic_smp_call_function_interrupt();
660 		break;
661 
662 	case IPI_CPU_STOP:
663 		ipi_cpu_stop(cpu);
664 		break;
665 
666 #ifdef CONFIG_IRQ_WORK
667 	case IPI_IRQ_WORK:
668 		irq_work_run();
669 		break;
670 #endif
671 
672 	case IPI_COMPLETION:
673 		ipi_complete(cpu);
674 		break;
675 
676 	case IPI_CPU_BACKTRACE:
677 		printk_deferred_enter();
678 		nmi_cpu_backtrace(get_irq_regs());
679 		printk_deferred_exit();
680 		break;
681 
682 	default:
683 		pr_crit("CPU%u: Unknown IPI message 0x%x\n",
684 		        cpu, ipinr);
685 		break;
686 	}
687 
688 	if ((unsigned)ipinr < NR_IPI)
689 		trace_ipi_exit_rcuidle(ipi_types[ipinr]);
690 }
691 
692 /* Legacy version, should go away once all irqchips have been converted */
693 void handle_IPI(int ipinr, struct pt_regs *regs)
694 {
695 	struct pt_regs *old_regs = set_irq_regs(regs);
696 
697 	irq_enter();
698 	do_handle_IPI(ipinr);
699 	irq_exit();
700 
701 	set_irq_regs(old_regs);
702 }
703 
704 static irqreturn_t ipi_handler(int irq, void *data)
705 {
706 	do_handle_IPI(irq - ipi_irq_base);
707 	return IRQ_HANDLED;
708 }
709 
710 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
711 {
712 	trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
713 	__ipi_send_mask(ipi_desc[ipinr], target);
714 }
715 
716 static void ipi_setup(int cpu)
717 {
718 	int i;
719 
720 	if (WARN_ON_ONCE(!ipi_irq_base))
721 		return;
722 
723 	for (i = 0; i < nr_ipi; i++)
724 		enable_percpu_irq(ipi_irq_base + i, 0);
725 }
726 
727 void __init set_smp_ipi_range(int ipi_base, int n)
728 {
729 	int i;
730 
731 	WARN_ON(n < MAX_IPI);
732 	nr_ipi = min(n, MAX_IPI);
733 
734 	for (i = 0; i < nr_ipi; i++) {
735 		int err;
736 
737 		err = request_percpu_irq(ipi_base + i, ipi_handler,
738 					 "IPI", &irq_stat);
739 		WARN_ON(err);
740 
741 		ipi_desc[i] = irq_to_desc(ipi_base + i);
742 		irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
743 	}
744 
745 	ipi_irq_base = ipi_base;
746 
747 	/* Setup the boot CPU immediately */
748 	ipi_setup(smp_processor_id());
749 }
750 
751 void smp_send_reschedule(int cpu)
752 {
753 	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
754 }
755 
756 void smp_send_stop(void)
757 {
758 	unsigned long timeout;
759 	struct cpumask mask;
760 
761 	cpumask_copy(&mask, cpu_online_mask);
762 	cpumask_clear_cpu(smp_processor_id(), &mask);
763 	if (!cpumask_empty(&mask))
764 		smp_cross_call(&mask, IPI_CPU_STOP);
765 
766 	/* Wait up to one second for other CPUs to stop */
767 	timeout = USEC_PER_SEC;
768 	while (num_online_cpus() > 1 && timeout--)
769 		udelay(1);
770 
771 	if (num_online_cpus() > 1)
772 		pr_warn("SMP: failed to stop secondary CPUs\n");
773 }
774 
775 /* In case panic() and panic() called at the same time on CPU1 and CPU2,
776  * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
777  * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
778  * kdump fails. So split out the panic_smp_self_stop() and add
779  * set_cpu_online(smp_processor_id(), false).
780  */
781 void panic_smp_self_stop(void)
782 {
783 	pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
784 	         smp_processor_id());
785 	set_cpu_online(smp_processor_id(), false);
786 	while (1)
787 		cpu_relax();
788 }
789 
790 /*
791  * not supported here
792  */
793 int setup_profiling_timer(unsigned int multiplier)
794 {
795 	return -EINVAL;
796 }
797 
798 #ifdef CONFIG_CPU_FREQ
799 
800 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
801 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
802 static unsigned long global_l_p_j_ref;
803 static unsigned long global_l_p_j_ref_freq;
804 
805 static int cpufreq_callback(struct notifier_block *nb,
806 					unsigned long val, void *data)
807 {
808 	struct cpufreq_freqs *freq = data;
809 	struct cpumask *cpus = freq->policy->cpus;
810 	int cpu, first = cpumask_first(cpus);
811 	unsigned int lpj;
812 
813 	if (freq->flags & CPUFREQ_CONST_LOOPS)
814 		return NOTIFY_OK;
815 
816 	if (!per_cpu(l_p_j_ref, first)) {
817 		for_each_cpu(cpu, cpus) {
818 			per_cpu(l_p_j_ref, cpu) =
819 				per_cpu(cpu_data, cpu).loops_per_jiffy;
820 			per_cpu(l_p_j_ref_freq, cpu) = freq->old;
821 		}
822 
823 		if (!global_l_p_j_ref) {
824 			global_l_p_j_ref = loops_per_jiffy;
825 			global_l_p_j_ref_freq = freq->old;
826 		}
827 	}
828 
829 	if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
830 	    (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
831 		loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
832 						global_l_p_j_ref_freq,
833 						freq->new);
834 
835 		lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
836 				    per_cpu(l_p_j_ref_freq, first), freq->new);
837 		for_each_cpu(cpu, cpus)
838 			per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
839 	}
840 	return NOTIFY_OK;
841 }
842 
843 static struct notifier_block cpufreq_notifier = {
844 	.notifier_call  = cpufreq_callback,
845 };
846 
847 static int __init register_cpufreq_notifier(void)
848 {
849 	return cpufreq_register_notifier(&cpufreq_notifier,
850 						CPUFREQ_TRANSITION_NOTIFIER);
851 }
852 core_initcall(register_cpufreq_notifier);
853 
854 #endif
855 
856 static void raise_nmi(cpumask_t *mask)
857 {
858 	__ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask);
859 }
860 
861 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
862 {
863 	nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
864 }
865