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/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/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/mpic.h>
  47 #include <asm/vdso_datapage.h>
  48 #ifdef CONFIG_PPC64
  49 #include <asm/paca.h>
  50 #endif
  51 #include <asm/debug.h>
  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 #ifdef CONFIG_HOTPLUG_CPU
  61 /* State of each CPU during hotplug phases */
  62 static DEFINE_PER_CPU(int, cpu_state) = { 0 };
  63 #endif
  64
  65 struct thread_info *secondary_ti;
  66
  67 DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
  68 DEFINE_PER_CPU(cpumask_var_t, cpu_core_map);
  69
  70 EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
  71 EXPORT_PER_CPU_SYMBOL(cpu_core_map);
  72
  73 /* SMP operations for this machine */
  74 struct smp_ops_t *smp_ops;
  75
  76 /* Can't be static due to PowerMac hackery */
  77 volatile unsigned int cpu_callin_map[NR_CPUS];
  78
  79 int smt_enabled_at_boot = 1;
  80
  81 static void (*crash_ipi_function_ptr)(struct pt_regs *) = NULL;
  82
  83 #ifdef CONFIG_PPC64
  84 int __devinit smp_generic_kick_cpu(int nr)
  85 {
  86         BUG_ON(nr < 0 || nr >= NR_CPUS);
  87
  88         /*
  89          * The processor is currently spinning, waiting for the
  90          * cpu_start field to become non-zero After we set cpu_start,
  91          * the processor will continue on to secondary_start
  92          */
  93         if (!paca[nr].cpu_start) {
  94                 paca[nr].cpu_start = 1;
  95                 smp_mb();
  96                 return 0;
  97         }
  98
  99 #ifdef CONFIG_HOTPLUG_CPU
 100         /*
 101          * Ok it's not there, so it might be soft-unplugged, let's
 102          * try to bring it back
 103          */
 104         per_cpu(cpu_state, nr) = CPU_UP_PREPARE;
 105         smp_wmb();
 106         smp_send_reschedule(nr);
 107 #endif /* CONFIG_HOTPLUG_CPU */
 108
 109         return 0;
 110 }
 111 #endif /* CONFIG_PPC64 */
 112
 113 static irqreturn_t call_function_action(int irq, void *data)
 114 {
 115         generic_smp_call_function_interrupt();
 116         return IRQ_HANDLED;
 117 }
 118
 119 static irqreturn_t reschedule_action(int irq, void *data)
 120 {
 121         scheduler_ipi();
 122         return IRQ_HANDLED;
 123 }
 124
 125 static irqreturn_t call_function_single_action(int irq, void *data)
 126 {
 127         generic_smp_call_function_single_interrupt();
 128         return IRQ_HANDLED;
 129 }
 130
 131 static irqreturn_t debug_ipi_action(int irq, void *data)
 132 {
 133         if (crash_ipi_function_ptr) {
 134                 crash_ipi_function_ptr(get_irq_regs());
 135                 return IRQ_HANDLED;
 136         }
 137
 138 #ifdef CONFIG_DEBUGGER
 139         debugger_ipi(get_irq_regs());
 140 #endif /* CONFIG_DEBUGGER */
 141
 142         return IRQ_HANDLED;
 143 }
 144
 145 static irq_handler_t smp_ipi_action[] = {
 146         [PPC_MSG_CALL_FUNCTION] =  call_function_action,
 147         [PPC_MSG_RESCHEDULE] = reschedule_action,
 148         [PPC_MSG_CALL_FUNC_SINGLE] = call_function_single_action,
 149         [PPC_MSG_DEBUGGER_BREAK] = debug_ipi_action,
 150 };
 151
 152 const char *smp_ipi_name[] = {
 153         [PPC_MSG_CALL_FUNCTION] =  "ipi call function",
 154         [PPC_MSG_RESCHEDULE] = "ipi reschedule",
 155         [PPC_MSG_CALL_FUNC_SINGLE] = "ipi call function single",
 156         [PPC_MSG_DEBUGGER_BREAK] = "ipi debugger",
 157 };
 158
 159 /* optional function to request ipi, for controllers with >= 4 ipis */
 160 int smp_request_message_ipi(int virq, int msg)
 161 {
 162         int err;
 163
 164         if (msg < 0 || msg > PPC_MSG_DEBUGGER_BREAK) {
 165                 return -EINVAL;
 166         }
 167 #if !defined(CONFIG_DEBUGGER) && !defined(CONFIG_KEXEC)
 168         if (msg == PPC_MSG_DEBUGGER_BREAK) {
 169                 return 1;
 170         }
 171 #endif
 172         err = request_irq(virq, smp_ipi_action[msg],
 173                           IRQF_PERCPU | IRQF_NO_THREAD,
 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 EXPORT_SYMBOL_GPL(smp_send_reschedule);
 249
 250 void arch_send_call_function_single_ipi(int cpu)
 251 {
 252         do_message_pass(cpu, PPC_MSG_CALL_FUNC_SINGLE);
 253 }
 254
 255 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 256 {
 257         unsigned int cpu;
 258
 259         for_each_cpu(cpu, mask)
 260                 do_message_pass(cpu, PPC_MSG_CALL_FUNCTION);
 261 }
 262
 263 #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
 264 void smp_send_debugger_break(void)
 265 {
 266         int cpu;
 267         int me = raw_smp_processor_id();
 268
 269         if (unlikely(!smp_ops))
 270                 return;
 271
 272         for_each_online_cpu(cpu)
 273                 if (cpu != me)
 274                         do_message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
 275 }
 276 #endif
 277
 278 #ifdef CONFIG_KEXEC
 279 void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *))
 280 {
 281         crash_ipi_function_ptr = crash_ipi_callback;
 282         if (crash_ipi_callback) {
 283                 mb();
 284                 smp_send_debugger_break();
 285         }
 286 }
 287 #endif
 288
 289 static void stop_this_cpu(void *dummy)
 290 {
 291         /* Remove this CPU */
 292         set_cpu_online(smp_processor_id(), false);
 293
 294         local_irq_disable();
 295         while (1)
 296                 ;
 297 }
 298
 299 void smp_send_stop(void)
 300 {
 301         smp_call_function(stop_this_cpu, NULL, 0);
 302 }
 303
 304 struct thread_info *current_set[NR_CPUS];
 305
 306 static void __devinit smp_store_cpu_info(int id)
 307 {
 308         per_cpu(cpu_pvr, id) = mfspr(SPRN_PVR);
 309 #ifdef CONFIG_PPC_FSL_BOOK3E
 310         per_cpu(next_tlbcam_idx, id)
 311                 = (mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY) - 1;
 312 #endif
 313 }
 314
 315 void __init smp_prepare_cpus(unsigned int max_cpus)
 316 {
 317         unsigned int cpu;
 318
 319         DBG("smp_prepare_cpus\n");
 320
 321         /*
 322          * setup_cpu may need to be called on the boot cpu. We havent
 323          * spun any cpus up but lets be paranoid.
 324          */
 325         BUG_ON(boot_cpuid != smp_processor_id());
 326
 327         /* Fixup boot cpu */
 328         smp_store_cpu_info(boot_cpuid);
 329         cpu_callin_map[boot_cpuid] = 1;
 330
 331         for_each_possible_cpu(cpu) {
 332                 zalloc_cpumask_var_node(&per_cpu(cpu_sibling_map, cpu),
 333                                         GFP_KERNEL, cpu_to_node(cpu));
 334                 zalloc_cpumask_var_node(&per_cpu(cpu_core_map, cpu),
 335                                         GFP_KERNEL, cpu_to_node(cpu));
 336         }
 337
 338         cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid));
 339         cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid));
 340
 341         if (smp_ops)
 342                 if (smp_ops->probe)
 343                         max_cpus = smp_ops->probe();
 344                 else
 345                         max_cpus = NR_CPUS;
 346         else
 347                 max_cpus = 1;
 348 }
 349
 350 void __devinit smp_prepare_boot_cpu(void)
 351 {
 352         BUG_ON(smp_processor_id() != boot_cpuid);
 353 #ifdef CONFIG_PPC64
 354         paca[boot_cpuid].__current = current;
 355 #endif
 356         current_set[boot_cpuid] = task_thread_info(current);
 357 }
 358
 359 #ifdef CONFIG_HOTPLUG_CPU
 360
 361 int generic_cpu_disable(void)
 362 {
 363         unsigned int cpu = smp_processor_id();
 364
 365         if (cpu == boot_cpuid)
 366                 return -EBUSY;
 367
 368         set_cpu_online(cpu, false);
 369 #ifdef CONFIG_PPC64
 370         vdso_data->processorCount--;
 371 #endif
 372         migrate_irqs();
 373         return 0;
 374 }
 375
 376 void generic_cpu_die(unsigned int cpu)
 377 {
 378         int i;
 379
 380         for (i = 0; i < 100; i++) {
 381                 smp_rmb();
 382                 if (per_cpu(cpu_state, cpu) == CPU_DEAD)
 383                         return;
 384                 msleep(100);
 385         }
 386         printk(KERN_ERR "CPU%d didn't die...\n", cpu);
 387 }
 388
 389 void generic_mach_cpu_die(void)
 390 {
 391         unsigned int cpu;
 392
 393         local_irq_disable();
 394         idle_task_exit();
 395         cpu = smp_processor_id();
 396         printk(KERN_DEBUG "CPU%d offline\n", cpu);
 397         __get_cpu_var(cpu_state) = CPU_DEAD;
 398         smp_wmb();
 399         while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
 400                 cpu_relax();
 401 }
 402
 403 void generic_set_cpu_dead(unsigned int cpu)
 404 {
 405         per_cpu(cpu_state, cpu) = CPU_DEAD;
 406 }
 407
 408 int generic_check_cpu_restart(unsigned int cpu)
 409 {
 410         return per_cpu(cpu_state, cpu) == CPU_UP_PREPARE;
 411 }
 412 #endif
 413
 414 static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle)
 415 {
 416         struct thread_info *ti = task_thread_info(idle);
 417
 418 #ifdef CONFIG_PPC64
 419         paca[cpu].__current = idle;
 420         paca[cpu].kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD;
 421 #endif
 422         ti->cpu = cpu;
 423         secondary_ti = current_set[cpu] = ti;
 424 }
 425
 426 int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
 427 {
 428         int rc, c;
 429
 430         if (smp_ops == NULL ||
 431             (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
 432                 return -EINVAL;
 433
 434         cpu_idle_thread_init(cpu, tidle);
 435
 436         /* Make sure callin-map entry is 0 (can be leftover a CPU
 437          * hotplug
 438          */
 439         cpu_callin_map[cpu] = 0;
 440
 441         /* The information for processor bringup must
 442          * be written out to main store before we release
 443          * the processor.
 444          */
 445         smp_mb();
 446
 447         /* wake up cpus */
 448         DBG("smp: kicking cpu %d\n", cpu);
 449         rc = smp_ops->kick_cpu(cpu);
 450         if (rc) {
 451                 pr_err("smp: failed starting cpu %d (rc %d)\n", cpu, rc);
 452                 return rc;
 453         }
 454
 455         /*
 456          * wait to see if the cpu made a callin (is actually up).
 457          * use this value that I found through experimentation.
 458          * -- Cort
 459          */
 460         if (system_state < SYSTEM_RUNNING)
 461                 for (c = 50000; c && !cpu_callin_map[cpu]; c--)
 462                         udelay(100);
 463 #ifdef CONFIG_HOTPLUG_CPU
 464         else
 465                 /*
 466                  * CPUs can take much longer to come up in the
 467                  * hotplug case.  Wait five seconds.
 468                  */
 469                 for (c = 5000; c && !cpu_callin_map[cpu]; c--)
 470                         msleep(1);
 471 #endif
 472
 473         if (!cpu_callin_map[cpu]) {
 474                 printk(KERN_ERR "Processor %u is stuck.\n", cpu);
 475                 return -ENOENT;
 476         }
 477
 478         DBG("Processor %u found.\n", cpu);
 479
 480         if (smp_ops->give_timebase)
 481                 smp_ops->give_timebase();
 482
 483         /* Wait until cpu puts itself in the online map */
 484         while (!cpu_online(cpu))
 485                 cpu_relax();
 486
 487         return 0;
 488 }
 489
 490 /* Return the value of the reg property corresponding to the given
 491  * logical cpu.
 492  */
 493 int cpu_to_core_id(int cpu)
 494 {
 495         struct device_node *np;
 496         const int *reg;
 497         int id = -1;
 498
 499         np = of_get_cpu_node(cpu, NULL);
 500         if (!np)
 501                 goto out;
 502
 503         reg = of_get_property(np, "reg", NULL);
 504         if (!reg)
 505                 goto out;
 506
 507         id = *reg;
 508 out:
 509         of_node_put(np);
 510         return id;
 511 }
 512
 513 /* Helper routines for cpu to core mapping */
 514 int cpu_core_index_of_thread(int cpu)
 515 {
 516         return cpu >> threads_shift;
 517 }
 518 EXPORT_SYMBOL_GPL(cpu_core_index_of_thread);
 519
 520 int cpu_first_thread_of_core(int core)
 521 {
 522         return core << threads_shift;
 523 }
 524 EXPORT_SYMBOL_GPL(cpu_first_thread_of_core);
 525
 526 /* Must be called when no change can occur to cpu_present_mask,
 527  * i.e. during cpu online or offline.
 528  */
 529 static struct device_node *cpu_to_l2cache(int cpu)
 530 {
 531         struct device_node *np;
 532         struct device_node *cache;
 533
 534         if (!cpu_present(cpu))
 535                 return NULL;
 536
 537         np = of_get_cpu_node(cpu, NULL);
 538         if (np == NULL)
 539                 return NULL;
 540
 541         cache = of_find_next_cache_node(np);
 542
 543         of_node_put(np);
 544
 545         return cache;
 546 }
 547
 548 /* Activate a secondary processor. */
 549 void __devinit start_secondary(void *unused)
 550 {
 551         unsigned int cpu = smp_processor_id();
 552         struct device_node *l2_cache;
 553         int i, base;
 554
 555         atomic_inc(&init_mm.mm_count);
 556         current->active_mm = &init_mm;
 557
 558         smp_store_cpu_info(cpu);
 559         set_dec(tb_ticks_per_jiffy);
 560         preempt_disable();
 561         cpu_callin_map[cpu] = 1;
 562
 563         if (smp_ops->setup_cpu)
 564                 smp_ops->setup_cpu(cpu);
 565         if (smp_ops->take_timebase)
 566                 smp_ops->take_timebase();
 567
 568         secondary_cpu_time_init();
 569
 570 #ifdef CONFIG_PPC64
 571         if (system_state == SYSTEM_RUNNING)
 572                 vdso_data->processorCount++;
 573 #endif
 574         notify_cpu_starting(cpu);
 575         set_cpu_online(cpu, true);
 576         /* Update sibling maps */
 577         base = cpu_first_thread_sibling(cpu);
 578         for (i = 0; i < threads_per_core; i++) {
 579                 if (cpu_is_offline(base + i))
 580                         continue;
 581                 cpumask_set_cpu(cpu, cpu_sibling_mask(base + i));
 582                 cpumask_set_cpu(base + i, cpu_sibling_mask(cpu));
 583
 584                 /* cpu_core_map should be a superset of
 585                  * cpu_sibling_map even if we don't have cache
 586                  * information, so update the former here, too.
 587                  */
 588                 cpumask_set_cpu(cpu, cpu_core_mask(base + i));
 589                 cpumask_set_cpu(base + i, cpu_core_mask(cpu));
 590         }
 591         l2_cache = cpu_to_l2cache(cpu);
 592         for_each_online_cpu(i) {
 593                 struct device_node *np = cpu_to_l2cache(i);
 594                 if (!np)
 595                         continue;
 596                 if (np == l2_cache) {
 597                         cpumask_set_cpu(cpu, cpu_core_mask(i));
 598                         cpumask_set_cpu(i, cpu_core_mask(cpu));
 599                 }
 600                 of_node_put(np);
 601         }
 602         of_node_put(l2_cache);
 603
 604         local_irq_enable();
 605
 606         cpu_idle();
 607
 608         BUG();
 609 }
 610
 611 int setup_profiling_timer(unsigned int multiplier)
 612 {
 613         return 0;
 614 }
 615
 616 void __init smp_cpus_done(unsigned int max_cpus)
 617 {
 618         cpumask_var_t old_mask;
 619
 620         /* We want the setup_cpu() here to be called from CPU 0, but our
 621          * init thread may have been "borrowed" by another CPU in the meantime
 622          * se we pin us down to CPU 0 for a short while
 623          */
 624         alloc_cpumask_var(&old_mask, GFP_NOWAIT);
 625         cpumask_copy(old_mask, tsk_cpus_allowed(current));
 626         set_cpus_allowed_ptr(current, cpumask_of(boot_cpuid));
 627
 628         if (smp_ops && smp_ops->setup_cpu)
 629                 smp_ops->setup_cpu(boot_cpuid);
 630
 631         set_cpus_allowed_ptr(current, old_mask);
 632
 633         free_cpumask_var(old_mask);
 634
 635         if (smp_ops && smp_ops->bringup_done)
 636                 smp_ops->bringup_done();
 637
 638         dump_numa_cpu_topology();
 639
 640 }
 641
 642 int arch_sd_sibling_asym_packing(void)
 643 {
 644         if (cpu_has_feature(CPU_FTR_ASYM_SMT)) {
 645                 printk_once(KERN_INFO "Enabling Asymmetric SMT scheduling\n");
 646                 return SD_ASYM_PACKING;
 647         }
 648         return 0;
 649 }
 650
 651 #ifdef CONFIG_HOTPLUG_CPU
 652 int __cpu_disable(void)
 653 {
 654         struct device_node *l2_cache;
 655         int cpu = smp_processor_id();
 656         int base, i;
 657         int err;
 658
 659         if (!smp_ops->cpu_disable)
 660                 return -ENOSYS;
 661
 662         err = smp_ops->cpu_disable();
 663         if (err)
 664                 return err;
 665
 666         /* Update sibling maps */
 667         base = cpu_first_thread_sibling(cpu);
 668         for (i = 0; i < threads_per_core; i++) {
 669                 cpumask_clear_cpu(cpu, cpu_sibling_mask(base + i));
 670                 cpumask_clear_cpu(base + i, cpu_sibling_mask(cpu));
 671                 cpumask_clear_cpu(cpu, cpu_core_mask(base + i));
 672                 cpumask_clear_cpu(base + i, cpu_core_mask(cpu));
 673         }
 674
 675         l2_cache = cpu_to_l2cache(cpu);
 676         for_each_present_cpu(i) {
 677                 struct device_node *np = cpu_to_l2cache(i);
 678                 if (!np)
 679                         continue;
 680                 if (np == l2_cache) {
 681                         cpumask_clear_cpu(cpu, cpu_core_mask(i));
 682                         cpumask_clear_cpu(i, cpu_core_mask(cpu));
 683                 }
 684                 of_node_put(np);
 685         }
 686         of_node_put(l2_cache);
 687
 688
 689         return 0;
 690 }
 691
 692 void __cpu_die(unsigned int cpu)
 693 {
 694         if (smp_ops->cpu_die)
 695                 smp_ops->cpu_die(cpu);
 696 }
 697
 698 static DEFINE_MUTEX(powerpc_cpu_hotplug_driver_mutex);
 699
 700 void cpu_hotplug_driver_lock()
 701 {
 702         mutex_lock(&powerpc_cpu_hotplug_driver_mutex);
 703 }
 704
 705 void cpu_hotplug_driver_unlock()
 706 {
 707         mutex_unlock(&powerpc_cpu_hotplug_driver_mutex);
 708 }
 709
 710 void cpu_die(void)
 711 {
 712         if (ppc_md.cpu_die)
 713                 ppc_md.cpu_die();
 714
 715         /* If we return, we re-enter start_secondary */
 716         start_secondary_resume();
 717 }
 718
 719 #endif