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/vdso.h>
  52 #include <asm/debug.h>
  53
  54 #ifdef DEBUG
  55 #include <asm/udbg.h>
  56 #define DBG(fmt...) udbg_printf(fmt)
  57 #else
  58 #define DBG(fmt...)
  59 #endif
  60
  61 #ifdef CONFIG_HOTPLUG_CPU
  62 /* State of each CPU during hotplug phases */
  63 static DEFINE_PER_CPU(int, cpu_state) = { 0 };
  64 #endif
  65
  66 struct thread_info *secondary_ti;
  67
  68 DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
  69 DEFINE_PER_CPU(cpumask_var_t, cpu_core_map);
  70
  71 EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
  72 EXPORT_PER_CPU_SYMBOL(cpu_core_map);
  73
  74 /* SMP operations for this machine */
  75 struct smp_ops_t *smp_ops;
  76
  77 /* Can't be static due to PowerMac hackery */
  78 volatile unsigned int cpu_callin_map[NR_CPUS];
  79
  80 int smt_enabled_at_boot = 1;
  81
  82 static void (*crash_ipi_function_ptr)(struct pt_regs *) = NULL;
  83
  84 #ifdef CONFIG_PPC64
  85 int __devinit smp_generic_kick_cpu(int nr)
  86 {
  87         BUG_ON(nr < 0 || nr >= NR_CPUS);
  88
  89         /*
  90          * The processor is currently spinning, waiting for the
  91          * cpu_start field to become non-zero After we set cpu_start,
  92          * the processor will continue on to secondary_start
  93          */
  94         if (!paca[nr].cpu_start) {
  95                 paca[nr].cpu_start = 1;
  96                 smp_mb();
  97                 return 0;
  98         }
  99
 100 #ifdef CONFIG_HOTPLUG_CPU
 101         /*
 102          * Ok it's not there, so it might be soft-unplugged, let's
 103          * try to bring it back
 104          */
 105         per_cpu(cpu_state, nr) = CPU_UP_PREPARE;
 106         smp_wmb();
 107         smp_send_reschedule(nr);
 108 #endif /* CONFIG_HOTPLUG_CPU */
 109
 110         return 0;
 111 }
 112 #endif /* CONFIG_PPC64 */
 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],
 174                           IRQF_PERCPU | IRQF_NO_THREAD,
 175                           smp_ipi_name[msg], 0);
 176         WARN(err < 0, "unable to request_irq %d for %s (rc %d)\n",
 177                 virq, smp_ipi_name[msg], err);
 178
 179         return err;
 180 }
 181
 182 #ifdef CONFIG_PPC_SMP_MUXED_IPI
 183 struct cpu_messages {
 184         int messages;                   /* current messages */
 185         unsigned long data;             /* data for cause ipi */
 186 };
 187 static DEFINE_PER_CPU_SHARED_ALIGNED(struct cpu_messages, ipi_message);
 188
 189 void smp_muxed_ipi_set_data(int cpu, unsigned long data)
 190 {
 191         struct cpu_messages *info = &per_cpu(ipi_message, cpu);
 192
 193         info->data = data;
 194 }
 195
 196 void smp_muxed_ipi_message_pass(int cpu, int msg)
 197 {
 198         struct cpu_messages *info = &per_cpu(ipi_message, cpu);
 199         char *message = (char *)&info->messages;
 200
 201         message[msg] = 1;
 202         mb();
 203         smp_ops->cause_ipi(cpu, info->data);
 204 }
 205
 206 irqreturn_t smp_ipi_demux(void)
 207 {
 208         struct cpu_messages *info = &__get_cpu_var(ipi_message);
 209         unsigned int all;
 210
 211         mb();   /* order any irq clear */
 212
 213         do {
 214                 all = xchg_local(&info->messages, 0);
 215
 216 #ifdef __BIG_ENDIAN
 217                 if (all & (1 << (24 - 8 * PPC_MSG_CALL_FUNCTION)))
 218                         generic_smp_call_function_interrupt();
 219                 if (all & (1 << (24 - 8 * PPC_MSG_RESCHEDULE)))
 220                         scheduler_ipi();
 221                 if (all & (1 << (24 - 8 * PPC_MSG_CALL_FUNC_SINGLE)))
 222                         generic_smp_call_function_single_interrupt();
 223                 if (all & (1 << (24 - 8 * PPC_MSG_DEBUGGER_BREAK)))
 224                         debug_ipi_action(0, NULL);
 225 #else
 226 #error Unsupported ENDIAN
 227 #endif
 228         } while (info->messages);
 229
 230         return IRQ_HANDLED;
 231 }
 232 #endif /* CONFIG_PPC_SMP_MUXED_IPI */
 233
 234 static inline void do_message_pass(int cpu, int msg)
 235 {
 236         if (smp_ops->message_pass)
 237                 smp_ops->message_pass(cpu, msg);
 238 #ifdef CONFIG_PPC_SMP_MUXED_IPI
 239         else
 240                 smp_muxed_ipi_message_pass(cpu, msg);
 241 #endif
 242 }
 243
 244 void smp_send_reschedule(int cpu)
 245 {
 246         if (likely(smp_ops))
 247                 do_message_pass(cpu, PPC_MSG_RESCHEDULE);
 248 }
 249 EXPORT_SYMBOL_GPL(smp_send_reschedule);
 250
 251 void arch_send_call_function_single_ipi(int cpu)
 252 {
 253         do_message_pass(cpu, PPC_MSG_CALL_FUNC_SINGLE);
 254 }
 255
 256 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 257 {
 258         unsigned int cpu;
 259
 260         for_each_cpu(cpu, mask)
 261                 do_message_pass(cpu, PPC_MSG_CALL_FUNCTION);
 262 }
 263
 264 #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
 265 void smp_send_debugger_break(void)
 266 {
 267         int cpu;
 268         int me = raw_smp_processor_id();
 269
 270         if (unlikely(!smp_ops))
 271                 return;
 272
 273         for_each_online_cpu(cpu)
 274                 if (cpu != me)
 275                         do_message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
 276 }
 277 #endif
 278
 279 #ifdef CONFIG_KEXEC
 280 void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *))
 281 {
 282         crash_ipi_function_ptr = crash_ipi_callback;
 283         if (crash_ipi_callback) {
 284                 mb();
 285                 smp_send_debugger_break();
 286         }
 287 }
 288 #endif
 289
 290 static void stop_this_cpu(void *dummy)
 291 {
 292         /* Remove this CPU */
 293         set_cpu_online(smp_processor_id(), false);
 294
 295         local_irq_disable();
 296         while (1)
 297                 ;
 298 }
 299
 300 void smp_send_stop(void)
 301 {
 302         smp_call_function(stop_this_cpu, NULL, 0);
 303 }
 304
 305 struct thread_info *current_set[NR_CPUS];
 306
 307 static void __devinit smp_store_cpu_info(int id)
 308 {
 309         per_cpu(cpu_pvr, id) = mfspr(SPRN_PVR);
 310 #ifdef CONFIG_PPC_FSL_BOOK3E
 311         per_cpu(next_tlbcam_idx, id)
 312                 = (mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY) - 1;
 313 #endif
 314 }
 315
 316 void __init smp_prepare_cpus(unsigned int max_cpus)
 317 {
 318         unsigned int cpu;
 319
 320         DBG("smp_prepare_cpus\n");
 321
 322         /*
 323          * setup_cpu may need to be called on the boot cpu. We havent
 324          * spun any cpus up but lets be paranoid.
 325          */
 326         BUG_ON(boot_cpuid != smp_processor_id());
 327
 328         /* Fixup boot cpu */
 329         smp_store_cpu_info(boot_cpuid);
 330         cpu_callin_map[boot_cpuid] = 1;
 331
 332         for_each_possible_cpu(cpu) {
 333                 zalloc_cpumask_var_node(&per_cpu(cpu_sibling_map, cpu),
 334                                         GFP_KERNEL, cpu_to_node(cpu));
 335                 zalloc_cpumask_var_node(&per_cpu(cpu_core_map, cpu),
 336                                         GFP_KERNEL, cpu_to_node(cpu));
 337         }
 338
 339         cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid));
 340         cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid));
 341
 342         if (smp_ops)
 343                 if (smp_ops->probe)
 344                         max_cpus = smp_ops->probe();
 345                 else
 346                         max_cpus = NR_CPUS;
 347         else
 348                 max_cpus = 1;
 349 }
 350
 351 void __devinit smp_prepare_boot_cpu(void)
 352 {
 353         BUG_ON(smp_processor_id() != boot_cpuid);
 354 #ifdef CONFIG_PPC64
 355         paca[boot_cpuid].__current = current;
 356 #endif
 357         current_set[boot_cpuid] = task_thread_info(current);
 358 }
 359
 360 #ifdef CONFIG_HOTPLUG_CPU
 361
 362 int generic_cpu_disable(void)
 363 {
 364         unsigned int cpu = smp_processor_id();
 365
 366         if (cpu == boot_cpuid)
 367                 return -EBUSY;
 368
 369         set_cpu_online(cpu, false);
 370 #ifdef CONFIG_PPC64
 371         vdso_data->processorCount--;
 372 #endif
 373         migrate_irqs();
 374         return 0;
 375 }
 376
 377 void generic_cpu_die(unsigned int cpu)
 378 {
 379         int i;
 380
 381         for (i = 0; i < 100; i++) {
 382                 smp_rmb();
 383                 if (per_cpu(cpu_state, cpu) == CPU_DEAD)
 384                         return;
 385                 msleep(100);
 386         }
 387         printk(KERN_ERR "CPU%d didn't die...\n", cpu);
 388 }
 389
 390 void generic_mach_cpu_die(void)
 391 {
 392         unsigned int cpu;
 393
 394         local_irq_disable();
 395         idle_task_exit();
 396         cpu = smp_processor_id();
 397         printk(KERN_DEBUG "CPU%d offline\n", cpu);
 398         __get_cpu_var(cpu_state) = CPU_DEAD;
 399         smp_wmb();
 400         while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
 401                 cpu_relax();
 402 }
 403
 404 void generic_set_cpu_dead(unsigned int cpu)
 405 {
 406         per_cpu(cpu_state, cpu) = CPU_DEAD;
 407 }
 408
 409 int generic_check_cpu_restart(unsigned int cpu)
 410 {
 411         return per_cpu(cpu_state, cpu) == CPU_UP_PREPARE;
 412 }
 413 #endif
 414
 415 static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle)
 416 {
 417         struct thread_info *ti = task_thread_info(idle);
 418
 419 #ifdef CONFIG_PPC64
 420         paca[cpu].__current = idle;
 421         paca[cpu].kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD;
 422 #endif
 423         ti->cpu = cpu;
 424         secondary_ti = current_set[cpu] = ti;
 425 }
 426
 427 int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
 428 {
 429         int rc, c;
 430
 431         if (smp_ops == NULL ||
 432             (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
 433                 return -EINVAL;
 434
 435         cpu_idle_thread_init(cpu, tidle);
 436
 437         /* Make sure callin-map entry is 0 (can be leftover a CPU
 438          * hotplug
 439          */
 440         cpu_callin_map[cpu] = 0;
 441
 442         /* The information for processor bringup must
 443          * be written out to main store before we release
 444          * the processor.
 445          */
 446         smp_mb();
 447
 448         /* wake up cpus */
 449         DBG("smp: kicking cpu %d\n", cpu);
 450         rc = smp_ops->kick_cpu(cpu);
 451         if (rc) {
 452                 pr_err("smp: failed starting cpu %d (rc %d)\n", cpu, rc);
 453                 return rc;
 454         }
 455
 456         /*
 457          * wait to see if the cpu made a callin (is actually up).
 458          * use this value that I found through experimentation.
 459          * -- Cort
 460          */
 461         if (system_state < SYSTEM_RUNNING)
 462                 for (c = 50000; c && !cpu_callin_map[cpu]; c--)
 463                         udelay(100);
 464 #ifdef CONFIG_HOTPLUG_CPU
 465         else
 466                 /*
 467                  * CPUs can take much longer to come up in the
 468                  * hotplug case.  Wait five seconds.
 469                  */
 470                 for (c = 5000; c && !cpu_callin_map[cpu]; c--)
 471                         msleep(1);
 472 #endif
 473
 474         if (!cpu_callin_map[cpu]) {
 475                 printk(KERN_ERR "Processor %u is stuck.\n", cpu);
 476                 return -ENOENT;
 477         }
 478
 479         DBG("Processor %u found.\n", cpu);
 480
 481         if (smp_ops->give_timebase)
 482                 smp_ops->give_timebase();
 483
 484         /* Wait until cpu puts itself in the online map */
 485         while (!cpu_online(cpu))
 486                 cpu_relax();
 487
 488         return 0;
 489 }
 490
 491 /* Return the value of the reg property corresponding to the given
 492  * logical cpu.
 493  */
 494 int cpu_to_core_id(int cpu)
 495 {
 496         struct device_node *np;
 497         const int *reg;
 498         int id = -1;
 499
 500         np = of_get_cpu_node(cpu, NULL);
 501         if (!np)
 502                 goto out;
 503
 504         reg = of_get_property(np, "reg", NULL);
 505         if (!reg)
 506                 goto out;
 507
 508         id = *reg;
 509 out:
 510         of_node_put(np);
 511         return id;
 512 }
 513
 514 /* Helper routines for cpu to core mapping */
 515 int cpu_core_index_of_thread(int cpu)
 516 {
 517         return cpu >> threads_shift;
 518 }
 519 EXPORT_SYMBOL_GPL(cpu_core_index_of_thread);
 520
 521 int cpu_first_thread_of_core(int core)
 522 {
 523         return core << threads_shift;
 524 }
 525 EXPORT_SYMBOL_GPL(cpu_first_thread_of_core);
 526
 527 /* Must be called when no change can occur to cpu_present_mask,
 528  * i.e. during cpu online or offline.
 529  */
 530 static struct device_node *cpu_to_l2cache(int cpu)
 531 {
 532         struct device_node *np;
 533         struct device_node *cache;
 534
 535         if (!cpu_present(cpu))
 536                 return NULL;
 537
 538         np = of_get_cpu_node(cpu, NULL);
 539         if (np == NULL)
 540                 return NULL;
 541
 542         cache = of_find_next_cache_node(np);
 543
 544         of_node_put(np);
 545
 546         return cache;
 547 }
 548
 549 /* Activate a secondary processor. */
 550 void __devinit start_secondary(void *unused)
 551 {
 552         unsigned int cpu = smp_processor_id();
 553         struct device_node *l2_cache;
 554         int i, base;
 555
 556         atomic_inc(&init_mm.mm_count);
 557         current->active_mm = &init_mm;
 558
 559         smp_store_cpu_info(cpu);
 560         set_dec(tb_ticks_per_jiffy);
 561         preempt_disable();
 562         cpu_callin_map[cpu] = 1;
 563
 564         if (smp_ops->setup_cpu)
 565                 smp_ops->setup_cpu(cpu);
 566         if (smp_ops->take_timebase)
 567                 smp_ops->take_timebase();
 568
 569         secondary_cpu_time_init();
 570
 571 #ifdef CONFIG_PPC64
 572         if (system_state == SYSTEM_RUNNING)
 573                 vdso_data->processorCount++;
 574
 575         vdso_getcpu_init();
 576 #endif
 577         notify_cpu_starting(cpu);
 578         set_cpu_online(cpu, true);
 579         /* Update sibling maps */
 580         base = cpu_first_thread_sibling(cpu);
 581         for (i = 0; i < threads_per_core; i++) {
 582                 if (cpu_is_offline(base + i))
 583                         continue;
 584                 cpumask_set_cpu(cpu, cpu_sibling_mask(base + i));
 585                 cpumask_set_cpu(base + i, cpu_sibling_mask(cpu));
 586
 587                 /* cpu_core_map should be a superset of
 588                  * cpu_sibling_map even if we don't have cache
 589                  * information, so update the former here, too.
 590                  */
 591                 cpumask_set_cpu(cpu, cpu_core_mask(base + i));
 592                 cpumask_set_cpu(base + i, cpu_core_mask(cpu));
 593         }
 594         l2_cache = cpu_to_l2cache(cpu);
 595         for_each_online_cpu(i) {
 596                 struct device_node *np = cpu_to_l2cache(i);
 597                 if (!np)
 598                         continue;
 599                 if (np == l2_cache) {
 600                         cpumask_set_cpu(cpu, cpu_core_mask(i));
 601                         cpumask_set_cpu(i, cpu_core_mask(cpu));
 602                 }
 603                 of_node_put(np);
 604         }
 605         of_node_put(l2_cache);
 606
 607         local_irq_enable();
 608
 609         cpu_idle();
 610
 611         BUG();
 612 }
 613
 614 int setup_profiling_timer(unsigned int multiplier)
 615 {
 616         return 0;
 617 }
 618
 619 void __init smp_cpus_done(unsigned int max_cpus)
 620 {
 621         cpumask_var_t old_mask;
 622
 623         /* We want the setup_cpu() here to be called from CPU 0, but our
 624          * init thread may have been "borrowed" by another CPU in the meantime
 625          * se we pin us down to CPU 0 for a short while
 626          */
 627         alloc_cpumask_var(&old_mask, GFP_NOWAIT);
 628         cpumask_copy(old_mask, tsk_cpus_allowed(current));
 629         set_cpus_allowed_ptr(current, cpumask_of(boot_cpuid));
 630
 631         if (smp_ops && smp_ops->setup_cpu)
 632                 smp_ops->setup_cpu(boot_cpuid);
 633
 634         set_cpus_allowed_ptr(current, old_mask);
 635
 636         free_cpumask_var(old_mask);
 637
 638         if (smp_ops && smp_ops->bringup_done)
 639                 smp_ops->bringup_done();
 640
 641         dump_numa_cpu_topology();
 642
 643 }
 644
 645 int arch_sd_sibling_asym_packing(void)
 646 {
 647         if (cpu_has_feature(CPU_FTR_ASYM_SMT)) {
 648                 printk_once(KERN_INFO "Enabling Asymmetric SMT scheduling\n");
 649                 return SD_ASYM_PACKING;
 650         }
 651         return 0;
 652 }
 653
 654 #ifdef CONFIG_HOTPLUG_CPU
 655 int __cpu_disable(void)
 656 {
 657         struct device_node *l2_cache;
 658         int cpu = smp_processor_id();
 659         int base, i;
 660         int err;
 661
 662         if (!smp_ops->cpu_disable)
 663                 return -ENOSYS;
 664
 665         err = smp_ops->cpu_disable();
 666         if (err)
 667                 return err;
 668
 669         /* Update sibling maps */
 670         base = cpu_first_thread_sibling(cpu);
 671         for (i = 0; i < threads_per_core; i++) {
 672                 cpumask_clear_cpu(cpu, cpu_sibling_mask(base + i));
 673                 cpumask_clear_cpu(base + i, cpu_sibling_mask(cpu));
 674                 cpumask_clear_cpu(cpu, cpu_core_mask(base + i));
 675                 cpumask_clear_cpu(base + i, cpu_core_mask(cpu));
 676         }
 677
 678         l2_cache = cpu_to_l2cache(cpu);
 679         for_each_present_cpu(i) {
 680                 struct device_node *np = cpu_to_l2cache(i);
 681                 if (!np)
 682                         continue;
 683                 if (np == l2_cache) {
 684                         cpumask_clear_cpu(cpu, cpu_core_mask(i));
 685                         cpumask_clear_cpu(i, cpu_core_mask(cpu));
 686                 }
 687                 of_node_put(np);
 688         }
 689         of_node_put(l2_cache);
 690
 691
 692         return 0;
 693 }
 694
 695 void __cpu_die(unsigned int cpu)
 696 {
 697         if (smp_ops->cpu_die)
 698                 smp_ops->cpu_die(cpu);
 699 }
 700
 701 static DEFINE_MUTEX(powerpc_cpu_hotplug_driver_mutex);
 702
 703 void cpu_hotplug_driver_lock()
 704 {
 705         mutex_lock(&powerpc_cpu_hotplug_driver_mutex);
 706 }
 707
 708 void cpu_hotplug_driver_unlock()
 709 {
 710         mutex_unlock(&powerpc_cpu_hotplug_driver_mutex);
 711 }
 712
 713 void cpu_die(void)
 714 {
 715         if (ppc_md.cpu_die)
 716                 ppc_md.cpu_die();
 717
 718         /* If we return, we re-enter start_secondary */
 719         start_secondary_resume();
 720 }
 721
 722 #endif