xref: /openbmc/linux/arch/powerpc/kernel/smp.c (revision b34e08d5)
1 /*
2  * SMP support for ppc.
3  *
4  * Written by Cort Dougan (cort@cs.nmt.edu) borrowing a great
5  * deal of code from the sparc and intel versions.
6  *
7  * Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
8  *
9  * PowerPC-64 Support added by Dave Engebretsen, Peter Bergner, and
10  * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
11  *
12  *      This program is free software; you can redistribute it and/or
13  *      modify it under the terms of the GNU General Public License
14  *      as published by the Free Software Foundation; either version
15  *      2 of the License, or (at your option) any later version.
16  */
17 
18 #undef DEBUG
19 
20 #include <linux/kernel.h>
21 #include <linux/export.h>
22 #include <linux/sched.h>
23 #include <linux/smp.h>
24 #include <linux/interrupt.h>
25 #include <linux/delay.h>
26 #include <linux/init.h>
27 #include <linux/spinlock.h>
28 #include <linux/cache.h>
29 #include <linux/err.h>
30 #include <linux/device.h>
31 #include <linux/cpu.h>
32 #include <linux/notifier.h>
33 #include <linux/topology.h>
34 
35 #include <asm/ptrace.h>
36 #include <linux/atomic.h>
37 #include <asm/irq.h>
38 #include <asm/hw_irq.h>
39 #include <asm/page.h>
40 #include <asm/pgtable.h>
41 #include <asm/prom.h>
42 #include <asm/smp.h>
43 #include <asm/time.h>
44 #include <asm/machdep.h>
45 #include <asm/cputhreads.h>
46 #include <asm/cputable.h>
47 #include <asm/mpic.h>
48 #include <asm/vdso_datapage.h>
49 #ifdef CONFIG_PPC64
50 #include <asm/paca.h>
51 #endif
52 #include <asm/vdso.h>
53 #include <asm/debug.h>
54 
55 #ifdef DEBUG
56 #include <asm/udbg.h>
57 #define DBG(fmt...) udbg_printf(fmt)
58 #else
59 #define DBG(fmt...)
60 #endif
61 
62 #ifdef CONFIG_HOTPLUG_CPU
63 /* State of each CPU during hotplug phases */
64 static DEFINE_PER_CPU(int, cpu_state) = { 0 };
65 #endif
66 
67 struct thread_info *secondary_ti;
68 
69 DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
70 DEFINE_PER_CPU(cpumask_var_t, cpu_core_map);
71 
72 EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
73 EXPORT_PER_CPU_SYMBOL(cpu_core_map);
74 
75 /* SMP operations for this machine */
76 struct smp_ops_t *smp_ops;
77 
78 /* Can't be static due to PowerMac hackery */
79 volatile unsigned int cpu_callin_map[NR_CPUS];
80 
81 int smt_enabled_at_boot = 1;
82 
83 static void (*crash_ipi_function_ptr)(struct pt_regs *) = NULL;
84 
85 /*
86  * Returns 1 if the specified cpu should be brought up during boot.
87  * Used to inhibit booting threads if they've been disabled or
88  * limited on the command line
89  */
90 int smp_generic_cpu_bootable(unsigned int nr)
91 {
92 	/* Special case - we inhibit secondary thread startup
93 	 * during boot if the user requests it.
94 	 */
95 	if (system_state == SYSTEM_BOOTING && cpu_has_feature(CPU_FTR_SMT)) {
96 		if (!smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
97 			return 0;
98 		if (smt_enabled_at_boot
99 		    && cpu_thread_in_core(nr) >= smt_enabled_at_boot)
100 			return 0;
101 	}
102 
103 	return 1;
104 }
105 
106 
107 #ifdef CONFIG_PPC64
108 int smp_generic_kick_cpu(int nr)
109 {
110 	BUG_ON(nr < 0 || nr >= NR_CPUS);
111 
112 	/*
113 	 * The processor is currently spinning, waiting for the
114 	 * cpu_start field to become non-zero After we set cpu_start,
115 	 * the processor will continue on to secondary_start
116 	 */
117 	if (!paca[nr].cpu_start) {
118 		paca[nr].cpu_start = 1;
119 		smp_mb();
120 		return 0;
121 	}
122 
123 #ifdef CONFIG_HOTPLUG_CPU
124 	/*
125 	 * Ok it's not there, so it might be soft-unplugged, let's
126 	 * try to bring it back
127 	 */
128 	generic_set_cpu_up(nr);
129 	smp_wmb();
130 	smp_send_reschedule(nr);
131 #endif /* CONFIG_HOTPLUG_CPU */
132 
133 	return 0;
134 }
135 #endif /* CONFIG_PPC64 */
136 
137 static irqreturn_t call_function_action(int irq, void *data)
138 {
139 	generic_smp_call_function_interrupt();
140 	return IRQ_HANDLED;
141 }
142 
143 static irqreturn_t reschedule_action(int irq, void *data)
144 {
145 	scheduler_ipi();
146 	return IRQ_HANDLED;
147 }
148 
149 static irqreturn_t tick_broadcast_ipi_action(int irq, void *data)
150 {
151 	tick_broadcast_ipi_handler();
152 	return IRQ_HANDLED;
153 }
154 
155 static irqreturn_t debug_ipi_action(int irq, void *data)
156 {
157 	if (crash_ipi_function_ptr) {
158 		crash_ipi_function_ptr(get_irq_regs());
159 		return IRQ_HANDLED;
160 	}
161 
162 #ifdef CONFIG_DEBUGGER
163 	debugger_ipi(get_irq_regs());
164 #endif /* CONFIG_DEBUGGER */
165 
166 	return IRQ_HANDLED;
167 }
168 
169 static irq_handler_t smp_ipi_action[] = {
170 	[PPC_MSG_CALL_FUNCTION] =  call_function_action,
171 	[PPC_MSG_RESCHEDULE] = reschedule_action,
172 	[PPC_MSG_TICK_BROADCAST] = tick_broadcast_ipi_action,
173 	[PPC_MSG_DEBUGGER_BREAK] = debug_ipi_action,
174 };
175 
176 const char *smp_ipi_name[] = {
177 	[PPC_MSG_CALL_FUNCTION] =  "ipi call function",
178 	[PPC_MSG_RESCHEDULE] = "ipi reschedule",
179 	[PPC_MSG_TICK_BROADCAST] = "ipi tick-broadcast",
180 	[PPC_MSG_DEBUGGER_BREAK] = "ipi debugger",
181 };
182 
183 /* optional function to request ipi, for controllers with >= 4 ipis */
184 int smp_request_message_ipi(int virq, int msg)
185 {
186 	int err;
187 
188 	if (msg < 0 || msg > PPC_MSG_DEBUGGER_BREAK) {
189 		return -EINVAL;
190 	}
191 #if !defined(CONFIG_DEBUGGER) && !defined(CONFIG_KEXEC)
192 	if (msg == PPC_MSG_DEBUGGER_BREAK) {
193 		return 1;
194 	}
195 #endif
196 	err = request_irq(virq, smp_ipi_action[msg],
197 			  IRQF_PERCPU | IRQF_NO_THREAD | IRQF_NO_SUSPEND,
198 			  smp_ipi_name[msg], NULL);
199 	WARN(err < 0, "unable to request_irq %d for %s (rc %d)\n",
200 		virq, smp_ipi_name[msg], err);
201 
202 	return err;
203 }
204 
205 #ifdef CONFIG_PPC_SMP_MUXED_IPI
206 struct cpu_messages {
207 	int messages;			/* current messages */
208 	unsigned long data;		/* data for cause ipi */
209 };
210 static DEFINE_PER_CPU_SHARED_ALIGNED(struct cpu_messages, ipi_message);
211 
212 void smp_muxed_ipi_set_data(int cpu, unsigned long data)
213 {
214 	struct cpu_messages *info = &per_cpu(ipi_message, cpu);
215 
216 	info->data = data;
217 }
218 
219 void smp_muxed_ipi_message_pass(int cpu, int msg)
220 {
221 	struct cpu_messages *info = &per_cpu(ipi_message, cpu);
222 	char *message = (char *)&info->messages;
223 
224 	/*
225 	 * Order previous accesses before accesses in the IPI handler.
226 	 */
227 	smp_mb();
228 	message[msg] = 1;
229 	/*
230 	 * cause_ipi functions are required to include a full barrier
231 	 * before doing whatever causes the IPI.
232 	 */
233 	smp_ops->cause_ipi(cpu, info->data);
234 }
235 
236 #ifdef __BIG_ENDIAN__
237 #define IPI_MESSAGE(A) (1 << (24 - 8 * (A)))
238 #else
239 #define IPI_MESSAGE(A) (1 << (8 * (A)))
240 #endif
241 
242 irqreturn_t smp_ipi_demux(void)
243 {
244 	struct cpu_messages *info = &__get_cpu_var(ipi_message);
245 	unsigned int all;
246 
247 	mb();	/* order any irq clear */
248 
249 	do {
250 		all = xchg(&info->messages, 0);
251 		if (all & IPI_MESSAGE(PPC_MSG_CALL_FUNCTION))
252 			generic_smp_call_function_interrupt();
253 		if (all & IPI_MESSAGE(PPC_MSG_RESCHEDULE))
254 			scheduler_ipi();
255 		if (all & IPI_MESSAGE(PPC_MSG_TICK_BROADCAST))
256 			tick_broadcast_ipi_handler();
257 		if (all & IPI_MESSAGE(PPC_MSG_DEBUGGER_BREAK))
258 			debug_ipi_action(0, NULL);
259 	} while (info->messages);
260 
261 	return IRQ_HANDLED;
262 }
263 #endif /* CONFIG_PPC_SMP_MUXED_IPI */
264 
265 static inline void do_message_pass(int cpu, int msg)
266 {
267 	if (smp_ops->message_pass)
268 		smp_ops->message_pass(cpu, msg);
269 #ifdef CONFIG_PPC_SMP_MUXED_IPI
270 	else
271 		smp_muxed_ipi_message_pass(cpu, msg);
272 #endif
273 }
274 
275 void smp_send_reschedule(int cpu)
276 {
277 	if (likely(smp_ops))
278 		do_message_pass(cpu, PPC_MSG_RESCHEDULE);
279 }
280 EXPORT_SYMBOL_GPL(smp_send_reschedule);
281 
282 void arch_send_call_function_single_ipi(int cpu)
283 {
284 	do_message_pass(cpu, PPC_MSG_CALL_FUNCTION);
285 }
286 
287 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
288 {
289 	unsigned int cpu;
290 
291 	for_each_cpu(cpu, mask)
292 		do_message_pass(cpu, PPC_MSG_CALL_FUNCTION);
293 }
294 
295 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
296 void tick_broadcast(const struct cpumask *mask)
297 {
298 	unsigned int cpu;
299 
300 	for_each_cpu(cpu, mask)
301 		do_message_pass(cpu, PPC_MSG_TICK_BROADCAST);
302 }
303 #endif
304 
305 #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
306 void smp_send_debugger_break(void)
307 {
308 	int cpu;
309 	int me = raw_smp_processor_id();
310 
311 	if (unlikely(!smp_ops))
312 		return;
313 
314 	for_each_online_cpu(cpu)
315 		if (cpu != me)
316 			do_message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
317 }
318 #endif
319 
320 #ifdef CONFIG_KEXEC
321 void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *))
322 {
323 	crash_ipi_function_ptr = crash_ipi_callback;
324 	if (crash_ipi_callback) {
325 		mb();
326 		smp_send_debugger_break();
327 	}
328 }
329 #endif
330 
331 static void stop_this_cpu(void *dummy)
332 {
333 	/* Remove this CPU */
334 	set_cpu_online(smp_processor_id(), false);
335 
336 	local_irq_disable();
337 	while (1)
338 		;
339 }
340 
341 void smp_send_stop(void)
342 {
343 	smp_call_function(stop_this_cpu, NULL, 0);
344 }
345 
346 struct thread_info *current_set[NR_CPUS];
347 
348 static void smp_store_cpu_info(int id)
349 {
350 	per_cpu(cpu_pvr, id) = mfspr(SPRN_PVR);
351 #ifdef CONFIG_PPC_FSL_BOOK3E
352 	per_cpu(next_tlbcam_idx, id)
353 		= (mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY) - 1;
354 #endif
355 }
356 
357 void __init smp_prepare_cpus(unsigned int max_cpus)
358 {
359 	unsigned int cpu;
360 
361 	DBG("smp_prepare_cpus\n");
362 
363 	/*
364 	 * setup_cpu may need to be called on the boot cpu. We havent
365 	 * spun any cpus up but lets be paranoid.
366 	 */
367 	BUG_ON(boot_cpuid != smp_processor_id());
368 
369 	/* Fixup boot cpu */
370 	smp_store_cpu_info(boot_cpuid);
371 	cpu_callin_map[boot_cpuid] = 1;
372 
373 	for_each_possible_cpu(cpu) {
374 		zalloc_cpumask_var_node(&per_cpu(cpu_sibling_map, cpu),
375 					GFP_KERNEL, cpu_to_node(cpu));
376 		zalloc_cpumask_var_node(&per_cpu(cpu_core_map, cpu),
377 					GFP_KERNEL, cpu_to_node(cpu));
378 	}
379 
380 	cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid));
381 	cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid));
382 
383 	if (smp_ops && smp_ops->probe)
384 		smp_ops->probe();
385 }
386 
387 void smp_prepare_boot_cpu(void)
388 {
389 	BUG_ON(smp_processor_id() != boot_cpuid);
390 #ifdef CONFIG_PPC64
391 	paca[boot_cpuid].__current = current;
392 #endif
393 	current_set[boot_cpuid] = task_thread_info(current);
394 }
395 
396 #ifdef CONFIG_HOTPLUG_CPU
397 
398 int generic_cpu_disable(void)
399 {
400 	unsigned int cpu = smp_processor_id();
401 
402 	if (cpu == boot_cpuid)
403 		return -EBUSY;
404 
405 	set_cpu_online(cpu, false);
406 #ifdef CONFIG_PPC64
407 	vdso_data->processorCount--;
408 #endif
409 	migrate_irqs();
410 	return 0;
411 }
412 
413 void generic_cpu_die(unsigned int cpu)
414 {
415 	int i;
416 
417 	for (i = 0; i < 100; i++) {
418 		smp_rmb();
419 		if (per_cpu(cpu_state, cpu) == CPU_DEAD)
420 			return;
421 		msleep(100);
422 	}
423 	printk(KERN_ERR "CPU%d didn't die...\n", cpu);
424 }
425 
426 void generic_mach_cpu_die(void)
427 {
428 	unsigned int cpu;
429 
430 	local_irq_disable();
431 	idle_task_exit();
432 	cpu = smp_processor_id();
433 	printk(KERN_DEBUG "CPU%d offline\n", cpu);
434 	__get_cpu_var(cpu_state) = CPU_DEAD;
435 	smp_wmb();
436 	while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
437 		cpu_relax();
438 }
439 
440 void generic_set_cpu_dead(unsigned int cpu)
441 {
442 	per_cpu(cpu_state, cpu) = CPU_DEAD;
443 }
444 
445 /*
446  * The cpu_state should be set to CPU_UP_PREPARE in kick_cpu(), otherwise
447  * the cpu_state is always CPU_DEAD after calling generic_set_cpu_dead(),
448  * which makes the delay in generic_cpu_die() not happen.
449  */
450 void generic_set_cpu_up(unsigned int cpu)
451 {
452 	per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
453 }
454 
455 int generic_check_cpu_restart(unsigned int cpu)
456 {
457 	return per_cpu(cpu_state, cpu) == CPU_UP_PREPARE;
458 }
459 
460 static atomic_t secondary_inhibit_count;
461 
462 /*
463  * Don't allow secondary CPU threads to come online
464  */
465 void inhibit_secondary_onlining(void)
466 {
467 	/*
468 	 * This makes secondary_inhibit_count stable during cpu
469 	 * online/offline operations.
470 	 */
471 	get_online_cpus();
472 
473 	atomic_inc(&secondary_inhibit_count);
474 	put_online_cpus();
475 }
476 EXPORT_SYMBOL_GPL(inhibit_secondary_onlining);
477 
478 /*
479  * Allow secondary CPU threads to come online again
480  */
481 void uninhibit_secondary_onlining(void)
482 {
483 	get_online_cpus();
484 	atomic_dec(&secondary_inhibit_count);
485 	put_online_cpus();
486 }
487 EXPORT_SYMBOL_GPL(uninhibit_secondary_onlining);
488 
489 static int secondaries_inhibited(void)
490 {
491 	return atomic_read(&secondary_inhibit_count);
492 }
493 
494 #else /* HOTPLUG_CPU */
495 
496 #define secondaries_inhibited()		0
497 
498 #endif
499 
500 static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle)
501 {
502 	struct thread_info *ti = task_thread_info(idle);
503 
504 #ifdef CONFIG_PPC64
505 	paca[cpu].__current = idle;
506 	paca[cpu].kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD;
507 #endif
508 	ti->cpu = cpu;
509 	secondary_ti = current_set[cpu] = ti;
510 }
511 
512 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
513 {
514 	int rc, c;
515 
516 	/*
517 	 * Don't allow secondary threads to come online if inhibited
518 	 */
519 	if (threads_per_core > 1 && secondaries_inhibited() &&
520 	    cpu % threads_per_core != 0)
521 		return -EBUSY;
522 
523 	if (smp_ops == NULL ||
524 	    (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
525 		return -EINVAL;
526 
527 	cpu_idle_thread_init(cpu, tidle);
528 
529 	/* Make sure callin-map entry is 0 (can be leftover a CPU
530 	 * hotplug
531 	 */
532 	cpu_callin_map[cpu] = 0;
533 
534 	/* The information for processor bringup must
535 	 * be written out to main store before we release
536 	 * the processor.
537 	 */
538 	smp_mb();
539 
540 	/* wake up cpus */
541 	DBG("smp: kicking cpu %d\n", cpu);
542 	rc = smp_ops->kick_cpu(cpu);
543 	if (rc) {
544 		pr_err("smp: failed starting cpu %d (rc %d)\n", cpu, rc);
545 		return rc;
546 	}
547 
548 	/*
549 	 * wait to see if the cpu made a callin (is actually up).
550 	 * use this value that I found through experimentation.
551 	 * -- Cort
552 	 */
553 	if (system_state < SYSTEM_RUNNING)
554 		for (c = 50000; c && !cpu_callin_map[cpu]; c--)
555 			udelay(100);
556 #ifdef CONFIG_HOTPLUG_CPU
557 	else
558 		/*
559 		 * CPUs can take much longer to come up in the
560 		 * hotplug case.  Wait five seconds.
561 		 */
562 		for (c = 5000; c && !cpu_callin_map[cpu]; c--)
563 			msleep(1);
564 #endif
565 
566 	if (!cpu_callin_map[cpu]) {
567 		printk(KERN_ERR "Processor %u is stuck.\n", cpu);
568 		return -ENOENT;
569 	}
570 
571 	DBG("Processor %u found.\n", cpu);
572 
573 	if (smp_ops->give_timebase)
574 		smp_ops->give_timebase();
575 
576 	/* Wait until cpu puts itself in the online map */
577 	while (!cpu_online(cpu))
578 		cpu_relax();
579 
580 	return 0;
581 }
582 
583 /* Return the value of the reg property corresponding to the given
584  * logical cpu.
585  */
586 int cpu_to_core_id(int cpu)
587 {
588 	struct device_node *np;
589 	const __be32 *reg;
590 	int id = -1;
591 
592 	np = of_get_cpu_node(cpu, NULL);
593 	if (!np)
594 		goto out;
595 
596 	reg = of_get_property(np, "reg", NULL);
597 	if (!reg)
598 		goto out;
599 
600 	id = be32_to_cpup(reg);
601 out:
602 	of_node_put(np);
603 	return id;
604 }
605 
606 /* Helper routines for cpu to core mapping */
607 int cpu_core_index_of_thread(int cpu)
608 {
609 	return cpu >> threads_shift;
610 }
611 EXPORT_SYMBOL_GPL(cpu_core_index_of_thread);
612 
613 int cpu_first_thread_of_core(int core)
614 {
615 	return core << threads_shift;
616 }
617 EXPORT_SYMBOL_GPL(cpu_first_thread_of_core);
618 
619 static void traverse_siblings_chip_id(int cpu, bool add, int chipid)
620 {
621 	const struct cpumask *mask;
622 	struct device_node *np;
623 	int i, plen;
624 	const __be32 *prop;
625 
626 	mask = add ? cpu_online_mask : cpu_present_mask;
627 	for_each_cpu(i, mask) {
628 		np = of_get_cpu_node(i, NULL);
629 		if (!np)
630 			continue;
631 		prop = of_get_property(np, "ibm,chip-id", &plen);
632 		if (prop && plen == sizeof(int) &&
633 		    of_read_number(prop, 1) == chipid) {
634 			if (add) {
635 				cpumask_set_cpu(cpu, cpu_core_mask(i));
636 				cpumask_set_cpu(i, cpu_core_mask(cpu));
637 			} else {
638 				cpumask_clear_cpu(cpu, cpu_core_mask(i));
639 				cpumask_clear_cpu(i, cpu_core_mask(cpu));
640 			}
641 		}
642 		of_node_put(np);
643 	}
644 }
645 
646 /* Must be called when no change can occur to cpu_present_mask,
647  * i.e. during cpu online or offline.
648  */
649 static struct device_node *cpu_to_l2cache(int cpu)
650 {
651 	struct device_node *np;
652 	struct device_node *cache;
653 
654 	if (!cpu_present(cpu))
655 		return NULL;
656 
657 	np = of_get_cpu_node(cpu, NULL);
658 	if (np == NULL)
659 		return NULL;
660 
661 	cache = of_find_next_cache_node(np);
662 
663 	of_node_put(np);
664 
665 	return cache;
666 }
667 
668 static void traverse_core_siblings(int cpu, bool add)
669 {
670 	struct device_node *l2_cache, *np;
671 	const struct cpumask *mask;
672 	int i, chip, plen;
673 	const __be32 *prop;
674 
675 	/* First see if we have ibm,chip-id properties in cpu nodes */
676 	np = of_get_cpu_node(cpu, NULL);
677 	if (np) {
678 		chip = -1;
679 		prop = of_get_property(np, "ibm,chip-id", &plen);
680 		if (prop && plen == sizeof(int))
681 			chip = of_read_number(prop, 1);
682 		of_node_put(np);
683 		if (chip >= 0) {
684 			traverse_siblings_chip_id(cpu, add, chip);
685 			return;
686 		}
687 	}
688 
689 	l2_cache = cpu_to_l2cache(cpu);
690 	mask = add ? cpu_online_mask : cpu_present_mask;
691 	for_each_cpu(i, mask) {
692 		np = cpu_to_l2cache(i);
693 		if (!np)
694 			continue;
695 		if (np == l2_cache) {
696 			if (add) {
697 				cpumask_set_cpu(cpu, cpu_core_mask(i));
698 				cpumask_set_cpu(i, cpu_core_mask(cpu));
699 			} else {
700 				cpumask_clear_cpu(cpu, cpu_core_mask(i));
701 				cpumask_clear_cpu(i, cpu_core_mask(cpu));
702 			}
703 		}
704 		of_node_put(np);
705 	}
706 	of_node_put(l2_cache);
707 }
708 
709 /* Activate a secondary processor. */
710 void start_secondary(void *unused)
711 {
712 	unsigned int cpu = smp_processor_id();
713 	int i, base;
714 
715 	atomic_inc(&init_mm.mm_count);
716 	current->active_mm = &init_mm;
717 
718 	smp_store_cpu_info(cpu);
719 	set_dec(tb_ticks_per_jiffy);
720 	preempt_disable();
721 	cpu_callin_map[cpu] = 1;
722 
723 	if (smp_ops->setup_cpu)
724 		smp_ops->setup_cpu(cpu);
725 	if (smp_ops->take_timebase)
726 		smp_ops->take_timebase();
727 
728 	secondary_cpu_time_init();
729 
730 #ifdef CONFIG_PPC64
731 	if (system_state == SYSTEM_RUNNING)
732 		vdso_data->processorCount++;
733 
734 	vdso_getcpu_init();
735 #endif
736 	/* Update sibling maps */
737 	base = cpu_first_thread_sibling(cpu);
738 	for (i = 0; i < threads_per_core; i++) {
739 		if (cpu_is_offline(base + i) && (cpu != base + i))
740 			continue;
741 		cpumask_set_cpu(cpu, cpu_sibling_mask(base + i));
742 		cpumask_set_cpu(base + i, cpu_sibling_mask(cpu));
743 
744 		/* cpu_core_map should be a superset of
745 		 * cpu_sibling_map even if we don't have cache
746 		 * information, so update the former here, too.
747 		 */
748 		cpumask_set_cpu(cpu, cpu_core_mask(base + i));
749 		cpumask_set_cpu(base + i, cpu_core_mask(cpu));
750 	}
751 	traverse_core_siblings(cpu, true);
752 
753 	smp_wmb();
754 	notify_cpu_starting(cpu);
755 	set_cpu_online(cpu, true);
756 
757 	local_irq_enable();
758 
759 	cpu_startup_entry(CPUHP_ONLINE);
760 
761 	BUG();
762 }
763 
764 int setup_profiling_timer(unsigned int multiplier)
765 {
766 	return 0;
767 }
768 
769 void __init smp_cpus_done(unsigned int max_cpus)
770 {
771 	cpumask_var_t old_mask;
772 
773 	/* We want the setup_cpu() here to be called from CPU 0, but our
774 	 * init thread may have been "borrowed" by another CPU in the meantime
775 	 * se we pin us down to CPU 0 for a short while
776 	 */
777 	alloc_cpumask_var(&old_mask, GFP_NOWAIT);
778 	cpumask_copy(old_mask, tsk_cpus_allowed(current));
779 	set_cpus_allowed_ptr(current, cpumask_of(boot_cpuid));
780 
781 	if (smp_ops && smp_ops->setup_cpu)
782 		smp_ops->setup_cpu(boot_cpuid);
783 
784 	set_cpus_allowed_ptr(current, old_mask);
785 
786 	free_cpumask_var(old_mask);
787 
788 	if (smp_ops && smp_ops->bringup_done)
789 		smp_ops->bringup_done();
790 
791 	dump_numa_cpu_topology();
792 
793 }
794 
795 int arch_sd_sibling_asym_packing(void)
796 {
797 	if (cpu_has_feature(CPU_FTR_ASYM_SMT)) {
798 		printk_once(KERN_INFO "Enabling Asymmetric SMT scheduling\n");
799 		return SD_ASYM_PACKING;
800 	}
801 	return 0;
802 }
803 
804 #ifdef CONFIG_HOTPLUG_CPU
805 int __cpu_disable(void)
806 {
807 	int cpu = smp_processor_id();
808 	int base, i;
809 	int err;
810 
811 	if (!smp_ops->cpu_disable)
812 		return -ENOSYS;
813 
814 	err = smp_ops->cpu_disable();
815 	if (err)
816 		return err;
817 
818 	/* Update sibling maps */
819 	base = cpu_first_thread_sibling(cpu);
820 	for (i = 0; i < threads_per_core; i++) {
821 		cpumask_clear_cpu(cpu, cpu_sibling_mask(base + i));
822 		cpumask_clear_cpu(base + i, cpu_sibling_mask(cpu));
823 		cpumask_clear_cpu(cpu, cpu_core_mask(base + i));
824 		cpumask_clear_cpu(base + i, cpu_core_mask(cpu));
825 	}
826 	traverse_core_siblings(cpu, false);
827 
828 	return 0;
829 }
830 
831 void __cpu_die(unsigned int cpu)
832 {
833 	if (smp_ops->cpu_die)
834 		smp_ops->cpu_die(cpu);
835 }
836 
837 void cpu_die(void)
838 {
839 	if (ppc_md.cpu_die)
840 		ppc_md.cpu_die();
841 
842 	/* If we return, we re-enter start_secondary */
843 	start_secondary_resume();
844 }
845 
846 #endif
847