powerpc/book3e-64: Reraise doorbell when masked by soft-irq-disable
[linux-2.6.git] / arch / powerpc / kernel / smp.c
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/module.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/sysdev.h>
31 #include <linux/cpu.h>
32 #include <linux/notifier.h>
33 #include <linux/topology.h>
34
35 #include <asm/ptrace.h>
36 #include <asm/atomic.h>
37 #include <asm/irq.h>
38 #include <asm/page.h>
39 #include <asm/pgtable.h>
40 #include <asm/prom.h>
41 #include <asm/smp.h>
42 #include <asm/time.h>
43 #include <asm/machdep.h>
44 #include <asm/cputhreads.h>
45 #include <asm/cputable.h>
46 #include <asm/system.h>
47 #include <asm/mpic.h>
48 #include <asm/vdso_datapage.h>
49 #ifdef CONFIG_PPC64
50 #include <asm/paca.h>
51 #endif
52
53 #ifdef DEBUG
54 #include <asm/udbg.h>
55 #define DBG(fmt...) udbg_printf(fmt)
56 #else
57 #define DBG(fmt...)
58 #endif
59
60
61 /* Store all idle threads, this can be reused instead of creating
62 * a new thread. Also avoids complicated thread destroy functionality
63 * for idle threads.
64 */
65 #ifdef CONFIG_HOTPLUG_CPU
66 /*
67  * Needed only for CONFIG_HOTPLUG_CPU because __cpuinitdata is
68  * removed after init for !CONFIG_HOTPLUG_CPU.
69  */
70 static DEFINE_PER_CPU(struct task_struct *, idle_thread_array);
71 #define get_idle_for_cpu(x)      (per_cpu(idle_thread_array, x))
72 #define set_idle_for_cpu(x, p)   (per_cpu(idle_thread_array, x) = (p))
73 #else
74 static struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ;
75 #define get_idle_for_cpu(x)      (idle_thread_array[(x)])
76 #define set_idle_for_cpu(x, p)   (idle_thread_array[(x)] = (p))
77 #endif
78
79 struct thread_info *secondary_ti;
80
81 DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
82 DEFINE_PER_CPU(cpumask_var_t, cpu_core_map);
83
84 EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
85 EXPORT_PER_CPU_SYMBOL(cpu_core_map);
86
87 /* SMP operations for this machine */
88 struct smp_ops_t *smp_ops;
89
90 /* Can't be static due to PowerMac hackery */
91 volatile unsigned int cpu_callin_map[NR_CPUS];
92
93 int smt_enabled_at_boot = 1;
94
95 static void (*crash_ipi_function_ptr)(struct pt_regs *) = NULL;
96
97 #ifdef CONFIG_PPC64
98 int __devinit smp_generic_kick_cpu(int nr)
99 {
100         BUG_ON(nr < 0 || nr >= NR_CPUS);
101
102         /*
103          * The processor is currently spinning, waiting for the
104          * cpu_start field to become non-zero After we set cpu_start,
105          * the processor will continue on to secondary_start
106          */
107         paca[nr].cpu_start = 1;
108         smp_mb();
109
110         return 0;
111 }
112 #endif
113
114 static irqreturn_t call_function_action(int irq, void *data)
115 {
116         generic_smp_call_function_interrupt();
117         return IRQ_HANDLED;
118 }
119
120 static irqreturn_t reschedule_action(int irq, void *data)
121 {
122         scheduler_ipi();
123         return IRQ_HANDLED;
124 }
125
126 static irqreturn_t call_function_single_action(int irq, void *data)
127 {
128         generic_smp_call_function_single_interrupt();
129         return IRQ_HANDLED;
130 }
131
132 static irqreturn_t debug_ipi_action(int irq, void *data)
133 {
134         if (crash_ipi_function_ptr) {
135                 crash_ipi_function_ptr(get_irq_regs());
136                 return IRQ_HANDLED;
137         }
138
139 #ifdef CONFIG_DEBUGGER
140         debugger_ipi(get_irq_regs());
141 #endif /* CONFIG_DEBUGGER */
142
143         return IRQ_HANDLED;
144 }
145
146 static irq_handler_t smp_ipi_action[] = {
147         [PPC_MSG_CALL_FUNCTION] =  call_function_action,
148         [PPC_MSG_RESCHEDULE] = reschedule_action,
149         [PPC_MSG_CALL_FUNC_SINGLE] = call_function_single_action,
150         [PPC_MSG_DEBUGGER_BREAK] = debug_ipi_action,
151 };
152
153 const char *smp_ipi_name[] = {
154         [PPC_MSG_CALL_FUNCTION] =  "ipi call function",
155         [PPC_MSG_RESCHEDULE] = "ipi reschedule",
156         [PPC_MSG_CALL_FUNC_SINGLE] = "ipi call function single",
157         [PPC_MSG_DEBUGGER_BREAK] = "ipi debugger",
158 };
159
160 /* optional function to request ipi, for controllers with >= 4 ipis */
161 int smp_request_message_ipi(int virq, int msg)
162 {
163         int err;
164
165         if (msg < 0 || msg > PPC_MSG_DEBUGGER_BREAK) {
166                 return -EINVAL;
167         }
168 #if !defined(CONFIG_DEBUGGER) && !defined(CONFIG_KEXEC)
169         if (msg == PPC_MSG_DEBUGGER_BREAK) {
170                 return 1;
171         }
172 #endif
173         err = request_irq(virq, smp_ipi_action[msg], IRQF_DISABLED|IRQF_PERCPU,
174                           smp_ipi_name[msg], 0);
175         WARN(err < 0, "unable to request_irq %d for %s (rc %d)\n",
176                 virq, smp_ipi_name[msg], err);
177
178         return err;
179 }
180
181 #ifdef CONFIG_PPC_SMP_MUXED_IPI
182 struct cpu_messages {
183         int messages;                   /* current messages */
184         unsigned long data;             /* data for cause ipi */
185 };
186 static DEFINE_PER_CPU_SHARED_ALIGNED(struct cpu_messages, ipi_message);
187
188 void smp_muxed_ipi_set_data(int cpu, unsigned long data)
189 {
190         struct cpu_messages *info = &per_cpu(ipi_message, cpu);
191
192         info->data = data;
193 }
194
195 void smp_muxed_ipi_message_pass(int cpu, int msg)
196 {
197         struct cpu_messages *info = &per_cpu(ipi_message, cpu);
198         char *message = (char *)&info->messages;
199
200         message[msg] = 1;
201         mb();
202         smp_ops->cause_ipi(cpu, info->data);
203 }
204
205 irqreturn_t smp_ipi_demux(void)
206 {
207         struct cpu_messages *info = &__get_cpu_var(ipi_message);
208         unsigned int all;
209
210         mb();   /* order any irq clear */
211
212         do {
213                 all = xchg_local(&info->messages, 0);
214
215 #ifdef __BIG_ENDIAN
216                 if (all & (1 << (24 - 8 * PPC_MSG_CALL_FUNCTION)))
217                         generic_smp_call_function_interrupt();
218                 if (all & (1 << (24 - 8 * PPC_MSG_RESCHEDULE)))
219                         scheduler_ipi();
220                 if (all & (1 << (24 - 8 * PPC_MSG_CALL_FUNC_SINGLE)))
221                         generic_smp_call_function_single_interrupt();
222                 if (all & (1 << (24 - 8 * PPC_MSG_DEBUGGER_BREAK)))
223                         debug_ipi_action(0, NULL);
224 #else
225 #error Unsupported ENDIAN
226 #endif
227         } while (info->messages);
228
229         return IRQ_HANDLED;
230 }
231 #endif /* CONFIG_PPC_SMP_MUXED_IPI */
232
233 static inline void do_message_pass(int cpu, int msg)
234 {
235         if (smp_ops->message_pass)
236                 smp_ops->message_pass(cpu, msg);
237 #ifdef CONFIG_PPC_SMP_MUXED_IPI
238         else
239                 smp_muxed_ipi_message_pass(cpu, msg);
240 #endif
241 }
242
243 void smp_send_reschedule(int cpu)
244 {
245         if (likely(smp_ops))
246                 do_message_pass(cpu, PPC_MSG_RESCHEDULE);
247 }
248
249 void arch_send_call_function_single_ipi(int cpu)
250 {
251         do_message_pass(cpu, PPC_MSG_CALL_FUNC_SINGLE);
252 }
253
254 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
255 {
256         unsigned int cpu;
257
258         for_each_cpu(cpu, mask)
259                 do_message_pass(cpu, PPC_MSG_CALL_FUNCTION);
260 }
261
262 #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
263 void smp_send_debugger_break(void)
264 {
265         int cpu;
266         int me = raw_smp_processor_id();
267
268         if (unlikely(!smp_ops))
269                 return;
270
271         for_each_online_cpu(cpu)
272                 if (cpu != me)
273                         do_message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
274 }
275 #endif
276
277 #ifdef CONFIG_KEXEC
278 void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *))
279 {
280         crash_ipi_function_ptr = crash_ipi_callback;
281         if (crash_ipi_callback) {
282                 mb();
283                 smp_send_debugger_break();
284         }
285 }
286 #endif
287
288 static void stop_this_cpu(void *dummy)
289 {
290         /* Remove this CPU */
291         set_cpu_online(smp_processor_id(), false);
292
293         local_irq_disable();
294         while (1)
295                 ;
296 }
297
298 void smp_send_stop(void)
299 {
300         smp_call_function(stop_this_cpu, NULL, 0);
301 }
302
303 struct thread_info *current_set[NR_CPUS];
304
305 static void __devinit smp_store_cpu_info(int id)
306 {
307         per_cpu(cpu_pvr, id) = mfspr(SPRN_PVR);
308 }
309
310 void __init smp_prepare_cpus(unsigned int max_cpus)
311 {
312         unsigned int cpu;
313
314         DBG("smp_prepare_cpus\n");
315
316         /* 
317          * setup_cpu may need to be called on the boot cpu. We havent
318          * spun any cpus up but lets be paranoid.
319          */
320         BUG_ON(boot_cpuid != smp_processor_id());
321
322         /* Fixup boot cpu */
323         smp_store_cpu_info(boot_cpuid);
324         cpu_callin_map[boot_cpuid] = 1;
325
326         for_each_possible_cpu(cpu) {
327                 zalloc_cpumask_var_node(&per_cpu(cpu_sibling_map, cpu),
328                                         GFP_KERNEL, cpu_to_node(cpu));
329                 zalloc_cpumask_var_node(&per_cpu(cpu_core_map, cpu),
330                                         GFP_KERNEL, cpu_to_node(cpu));
331         }
332
333         cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid));
334         cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid));
335
336         if (smp_ops)
337                 if (smp_ops->probe)
338                         max_cpus = smp_ops->probe();
339                 else
340                         max_cpus = NR_CPUS;
341         else
342                 max_cpus = 1;
343 }
344
345 void __devinit smp_prepare_boot_cpu(void)
346 {
347         BUG_ON(smp_processor_id() != boot_cpuid);
348 #ifdef CONFIG_PPC64
349         paca[boot_cpuid].__current = current;
350 #endif
351         current_set[boot_cpuid] = task_thread_info(current);
352 }
353
354 #ifdef CONFIG_HOTPLUG_CPU
355 /* State of each CPU during hotplug phases */
356 static DEFINE_PER_CPU(int, cpu_state) = { 0 };
357
358 int generic_cpu_disable(void)
359 {
360         unsigned int cpu = smp_processor_id();
361
362         if (cpu == boot_cpuid)
363                 return -EBUSY;
364
365         set_cpu_online(cpu, false);
366 #ifdef CONFIG_PPC64
367         vdso_data->processorCount--;
368 #endif
369         migrate_irqs();
370         return 0;
371 }
372
373 void generic_cpu_die(unsigned int cpu)
374 {
375         int i;
376
377         for (i = 0; i < 100; i++) {
378                 smp_rmb();
379                 if (per_cpu(cpu_state, cpu) == CPU_DEAD)
380                         return;
381                 msleep(100);
382         }
383         printk(KERN_ERR "CPU%d didn't die...\n", cpu);
384 }
385
386 void generic_mach_cpu_die(void)
387 {
388         unsigned int cpu;
389
390         local_irq_disable();
391         idle_task_exit();
392         cpu = smp_processor_id();
393         printk(KERN_DEBUG "CPU%d offline\n", cpu);
394         __get_cpu_var(cpu_state) = CPU_DEAD;
395         smp_wmb();
396         while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
397                 cpu_relax();
398 }
399
400 void generic_set_cpu_dead(unsigned int cpu)
401 {
402         per_cpu(cpu_state, cpu) = CPU_DEAD;
403 }
404 #endif
405
406 struct create_idle {
407         struct work_struct work;
408         struct task_struct *idle;
409         struct completion done;
410         int cpu;
411 };
412
413 static void __cpuinit do_fork_idle(struct work_struct *work)
414 {
415         struct create_idle *c_idle =
416                 container_of(work, struct create_idle, work);
417
418         c_idle->idle = fork_idle(c_idle->cpu);
419         complete(&c_idle->done);
420 }
421
422 static int __cpuinit create_idle(unsigned int cpu)
423 {
424         struct thread_info *ti;
425         struct create_idle c_idle = {
426                 .cpu    = cpu,
427                 .done   = COMPLETION_INITIALIZER_ONSTACK(c_idle.done),
428         };
429         INIT_WORK_ONSTACK(&c_idle.work, do_fork_idle);
430
431         c_idle.idle = get_idle_for_cpu(cpu);
432
433         /* We can't use kernel_thread since we must avoid to
434          * reschedule the child. We use a workqueue because
435          * we want to fork from a kernel thread, not whatever
436          * userspace process happens to be trying to online us.
437          */
438         if (!c_idle.idle) {
439                 schedule_work(&c_idle.work);
440                 wait_for_completion(&c_idle.done);
441         } else
442                 init_idle(c_idle.idle, cpu);
443         if (IS_ERR(c_idle.idle)) {              
444                 pr_err("Failed fork for CPU %u: %li", cpu, PTR_ERR(c_idle.idle));
445                 return PTR_ERR(c_idle.idle);
446         }
447         ti = task_thread_info(c_idle.idle);
448
449 #ifdef CONFIG_PPC64
450         paca[cpu].__current = c_idle.idle;
451         paca[cpu].kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD;
452 #endif
453         ti->cpu = cpu;
454         current_set[cpu] = ti;
455
456         return 0;
457 }
458
459 int __cpuinit __cpu_up(unsigned int cpu)
460 {
461         int rc, c;
462
463         if (smp_ops == NULL ||
464             (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
465                 return -EINVAL;
466
467         /* Make sure we have an idle thread */
468         rc = create_idle(cpu);
469         if (rc)
470                 return rc;
471
472         secondary_ti = current_set[cpu];
473
474         /* Make sure callin-map entry is 0 (can be leftover a CPU
475          * hotplug
476          */
477         cpu_callin_map[cpu] = 0;
478
479         /* The information for processor bringup must
480          * be written out to main store before we release
481          * the processor.
482          */
483         smp_mb();
484
485         /* wake up cpus */
486         DBG("smp: kicking cpu %d\n", cpu);
487         rc = smp_ops->kick_cpu(cpu);
488         if (rc) {
489                 pr_err("smp: failed starting cpu %d (rc %d)\n", cpu, rc);
490                 return rc;
491         }
492
493         /*
494          * wait to see if the cpu made a callin (is actually up).
495          * use this value that I found through experimentation.
496          * -- Cort
497          */
498         if (system_state < SYSTEM_RUNNING)
499                 for (c = 50000; c && !cpu_callin_map[cpu]; c--)
500                         udelay(100);
501 #ifdef CONFIG_HOTPLUG_CPU
502         else
503                 /*
504                  * CPUs can take much longer to come up in the
505                  * hotplug case.  Wait five seconds.
506                  */
507                 for (c = 5000; c && !cpu_callin_map[cpu]; c--)
508                         msleep(1);
509 #endif
510
511         if (!cpu_callin_map[cpu]) {
512                 printk(KERN_ERR "Processor %u is stuck.\n", cpu);
513                 return -ENOENT;
514         }
515
516         DBG("Processor %u found.\n", cpu);
517
518         if (smp_ops->give_timebase)
519                 smp_ops->give_timebase();
520
521         /* Wait until cpu puts itself in the online map */
522         while (!cpu_online(cpu))
523                 cpu_relax();
524
525         return 0;
526 }
527
528 /* Return the value of the reg property corresponding to the given
529  * logical cpu.
530  */
531 int cpu_to_core_id(int cpu)
532 {
533         struct device_node *np;
534         const int *reg;
535         int id = -1;
536
537         np = of_get_cpu_node(cpu, NULL);
538         if (!np)
539                 goto out;
540
541         reg = of_get_property(np, "reg", NULL);
542         if (!reg)
543                 goto out;
544
545         id = *reg;
546 out:
547         of_node_put(np);
548         return id;
549 }
550
551 /* Helper routines for cpu to core mapping */
552 int cpu_core_index_of_thread(int cpu)
553 {
554         return cpu >> threads_shift;
555 }
556 EXPORT_SYMBOL_GPL(cpu_core_index_of_thread);
557
558 int cpu_first_thread_of_core(int core)
559 {
560         return core << threads_shift;
561 }
562 EXPORT_SYMBOL_GPL(cpu_first_thread_of_core);
563
564 /* Must be called when no change can occur to cpu_present_mask,
565  * i.e. during cpu online or offline.
566  */
567 static struct device_node *cpu_to_l2cache(int cpu)
568 {
569         struct device_node *np;
570         struct device_node *cache;
571
572         if (!cpu_present(cpu))
573                 return NULL;
574
575         np = of_get_cpu_node(cpu, NULL);
576         if (np == NULL)
577                 return NULL;
578
579         cache = of_find_next_cache_node(np);
580
581         of_node_put(np);
582
583         return cache;
584 }
585
586 /* Activate a secondary processor. */
587 void __devinit start_secondary(void *unused)
588 {
589         unsigned int cpu = smp_processor_id();
590         struct device_node *l2_cache;
591         int i, base;
592
593         atomic_inc(&init_mm.mm_count);
594         current->active_mm = &init_mm;
595
596         smp_store_cpu_info(cpu);
597         set_dec(tb_ticks_per_jiffy);
598         preempt_disable();
599         cpu_callin_map[cpu] = 1;
600
601         if (smp_ops->setup_cpu)
602                 smp_ops->setup_cpu(cpu);
603         if (smp_ops->take_timebase)
604                 smp_ops->take_timebase();
605
606         secondary_cpu_time_init();
607
608 #ifdef CONFIG_PPC64
609         if (system_state == SYSTEM_RUNNING)
610                 vdso_data->processorCount++;
611 #endif
612         ipi_call_lock();
613         notify_cpu_starting(cpu);
614         set_cpu_online(cpu, true);
615         /* Update sibling maps */
616         base = cpu_first_thread_sibling(cpu);
617         for (i = 0; i < threads_per_core; i++) {
618                 if (cpu_is_offline(base + i))
619                         continue;
620                 cpumask_set_cpu(cpu, cpu_sibling_mask(base + i));
621                 cpumask_set_cpu(base + i, cpu_sibling_mask(cpu));
622
623                 /* cpu_core_map should be a superset of
624                  * cpu_sibling_map even if we don't have cache
625                  * information, so update the former here, too.
626                  */
627                 cpumask_set_cpu(cpu, cpu_core_mask(base + i));
628                 cpumask_set_cpu(base + i, cpu_core_mask(cpu));
629         }
630         l2_cache = cpu_to_l2cache(cpu);
631         for_each_online_cpu(i) {
632                 struct device_node *np = cpu_to_l2cache(i);
633                 if (!np)
634                         continue;
635                 if (np == l2_cache) {
636                         cpumask_set_cpu(cpu, cpu_core_mask(i));
637                         cpumask_set_cpu(i, cpu_core_mask(cpu));
638                 }
639                 of_node_put(np);
640         }
641         of_node_put(l2_cache);
642         ipi_call_unlock();
643
644         local_irq_enable();
645
646         cpu_idle();
647
648         BUG();
649 }
650
651 int setup_profiling_timer(unsigned int multiplier)
652 {
653         return 0;
654 }
655
656 void __init smp_cpus_done(unsigned int max_cpus)
657 {
658         cpumask_var_t old_mask;
659
660         /* We want the setup_cpu() here to be called from CPU 0, but our
661          * init thread may have been "borrowed" by another CPU in the meantime
662          * se we pin us down to CPU 0 for a short while
663          */
664         alloc_cpumask_var(&old_mask, GFP_NOWAIT);
665         cpumask_copy(old_mask, tsk_cpus_allowed(current));
666         set_cpus_allowed_ptr(current, cpumask_of(boot_cpuid));
667         
668         if (smp_ops && smp_ops->setup_cpu)
669                 smp_ops->setup_cpu(boot_cpuid);
670
671         set_cpus_allowed_ptr(current, old_mask);
672
673         free_cpumask_var(old_mask);
674
675         if (smp_ops && smp_ops->bringup_done)
676                 smp_ops->bringup_done();
677
678         dump_numa_cpu_topology();
679
680 }
681
682 int arch_sd_sibling_asym_packing(void)
683 {
684         if (cpu_has_feature(CPU_FTR_ASYM_SMT)) {
685                 printk_once(KERN_INFO "Enabling Asymmetric SMT scheduling\n");
686                 return SD_ASYM_PACKING;
687         }
688         return 0;
689 }
690
691 #ifdef CONFIG_HOTPLUG_CPU
692 int __cpu_disable(void)
693 {
694         struct device_node *l2_cache;
695         int cpu = smp_processor_id();
696         int base, i;
697         int err;
698
699         if (!smp_ops->cpu_disable)
700                 return -ENOSYS;
701
702         err = smp_ops->cpu_disable();
703         if (err)
704                 return err;
705
706         /* Update sibling maps */
707         base = cpu_first_thread_sibling(cpu);
708         for (i = 0; i < threads_per_core; i++) {
709                 cpumask_clear_cpu(cpu, cpu_sibling_mask(base + i));
710                 cpumask_clear_cpu(base + i, cpu_sibling_mask(cpu));
711                 cpumask_clear_cpu(cpu, cpu_core_mask(base + i));
712                 cpumask_clear_cpu(base + i, cpu_core_mask(cpu));
713         }
714
715         l2_cache = cpu_to_l2cache(cpu);
716         for_each_present_cpu(i) {
717                 struct device_node *np = cpu_to_l2cache(i);
718                 if (!np)
719                         continue;
720                 if (np == l2_cache) {
721                         cpumask_clear_cpu(cpu, cpu_core_mask(i));
722                         cpumask_clear_cpu(i, cpu_core_mask(cpu));
723                 }
724                 of_node_put(np);
725         }
726         of_node_put(l2_cache);
727
728
729         return 0;
730 }
731
732 void __cpu_die(unsigned int cpu)
733 {
734         if (smp_ops->cpu_die)
735                 smp_ops->cpu_die(cpu);
736 }
737
738 static DEFINE_MUTEX(powerpc_cpu_hotplug_driver_mutex);
739
740 void cpu_hotplug_driver_lock()
741 {
742         mutex_lock(&powerpc_cpu_hotplug_driver_mutex);
743 }
744
745 void cpu_hotplug_driver_unlock()
746 {
747         mutex_unlock(&powerpc_cpu_hotplug_driver_mutex);
748 }
749
750 void cpu_die(void)
751 {
752         if (ppc_md.cpu_die)
753                 ppc_md.cpu_die();
754
755         /* If we return, we re-enter start_secondary */
756         start_secondary_resume();
757 }
758
759 #endif