kernel/arch/arm/kernel/smp.c

   1 /*
   2  *  linux/arch/arm/kernel/smp.c
   3  *
   4  *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/module.h>
  11 #include <linux/delay.h>
  12 #include <linux/init.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/sched.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/cache.h>
  17 #include <linux/profile.h>
  18 #include <linux/errno.h>
  19 #include <linux/mm.h>
  20 #include <linux/err.h>
  21 #include <linux/cpu.h>
  22 #include <linux/seq_file.h>
  23 #include <linux/irq.h>
  24 #include <linux/nmi.h>
  25 #include <linux/percpu.h>
  26 #include <linux/clockchips.h>
  27 #include <linux/completion.h>
  28 #include <linux/cpufreq.h>
  29 #include <linux/irq_work.h>
  30
  31 #include <linux/atomic.h>
  32 #include <asm/smp.h>
  33 #include <asm/cacheflush.h>
  34 #include <asm/cpu.h>
  35 #include <asm/cputype.h>
  36 #include <asm/exception.h>
  37 #include <asm/idmap.h>
  38 #include <asm/topology.h>
  39 #include <asm/mmu_context.h>
  40 #include <asm/pgtable.h>
  41 #include <asm/pgalloc.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 /*
  62  * control for which core is the next to come out of the secondary
  63  * boot "holding pen"
  64  */
  65 volatile int pen_release = -1;
  66
  67 enum ipi_msg_type {
  68         IPI_WAKEUP,
  69         IPI_TIMER,
  70         IPI_RESCHEDULE,
  71         IPI_CALL_FUNC,
  72         IPI_CALL_FUNC_SINGLE,
  73         IPI_CPU_STOP,
  74         IPI_IRQ_WORK,
  75         IPI_COMPLETION,
  76         IPI_CPU_BACKTRACE = 15,
  77 };
  78
  79 static DECLARE_COMPLETION(cpu_running);
  80
  81 static struct smp_operations smp_ops;
  82
  83 void __init smp_set_ops(const struct smp_operations *ops)
  84 {
  85         if (ops)
  86                 smp_ops = *ops;
  87 };
  88
  89 static unsigned long get_arch_pgd(pgd_t *pgd)
  90 {
  91 #ifdef CONFIG_ARM_LPAE
  92         return __phys_to_pfn(virt_to_phys(pgd));
  93 #else
  94         return virt_to_phys(pgd);
  95 #endif
  96 }
  97
  98 int __cpu_up(unsigned int cpu, struct task_struct *idle)
  99 {
 100         int ret;
 101
 102         if (!smp_ops.smp_boot_secondary)
 103                 return -ENOSYS;
 104
 105         /*
 106          * We need to tell the secondary core where to find
 107          * its stack and the page tables.
 108          */
 109         secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
 110 #ifdef CONFIG_ARM_MPU
 111         secondary_data.mpu_rgn_szr = mpu_rgn_info.rgns[MPU_RAM_REGION].drsr;
 112 #endif
 113
 114 #ifdef CONFIG_MMU
 115         secondary_data.pgdir = virt_to_phys(idmap_pgd);
 116         secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
 117 #endif
 118         sync_cache_w(&secondary_data);
 119
 120         /*
 121          * Now bring the CPU into our world.
 122          */
 123         ret = smp_ops.smp_boot_secondary(cpu, idle);
 124         if (ret == 0) {
 125                 /*
 126                  * CPU was successfully started, wait for it
 127                  * to come online or time out.
 128                  */
 129                 wait_for_completion_timeout(&cpu_running,
 130                                                  msecs_to_jiffies(1000));
 131
 132                 if (!cpu_online(cpu)) {
 133                         pr_crit("CPU%u: failed to come online\n", cpu);
 134                         ret = -EIO;
 135                 }
 136         } else {
 137                 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
 138         }
 139
 140
 141         memset(&secondary_data, 0, sizeof(secondary_data));
 142         return ret;
 143 }
 144
 145 /* platform specific SMP operations */
 146 void __init smp_init_cpus(void)
 147 {
 148         if (smp_ops.smp_init_cpus)
 149                 smp_ops.smp_init_cpus();
 150 }
 151
 152 int platform_can_secondary_boot(void)
 153 {
 154         return !!smp_ops.smp_boot_secondary;
 155 }
 156
 157 int platform_can_cpu_hotplug(void)
 158 {
 159 #ifdef CONFIG_HOTPLUG_CPU
 160         if (smp_ops.cpu_kill)
 161                 return 1;
 162 #endif
 163
 164         return 0;
 165 }
 166
 167 #ifdef CONFIG_HOTPLUG_CPU
 168 static int platform_cpu_kill(unsigned int cpu)
 169 {
 170         if (smp_ops.cpu_kill)
 171                 return smp_ops.cpu_kill(cpu);
 172         return 1;
 173 }
 174
 175 static int platform_cpu_disable(unsigned int cpu)
 176 {
 177         if (smp_ops.cpu_disable)
 178                 return smp_ops.cpu_disable(cpu);
 179
 180         return 0;
 181 }
 182
 183 int platform_can_hotplug_cpu(unsigned int cpu)
 184 {
 185         /* cpu_die must be specified to support hotplug */
 186         if (!smp_ops.cpu_die)
 187                 return 0;
 188
 189         if (smp_ops.cpu_can_disable)
 190                 return smp_ops.cpu_can_disable(cpu);
 191
 192         /*
 193          * By default, allow disabling all CPUs except the first one,
 194          * since this is special on a lot of platforms, e.g. because
 195          * of clock tick interrupts.
 196          */
 197         return cpu != 0;
 198 }
 199
 200 /*
 201  * __cpu_disable runs on the processor to be shutdown.
 202  */
 203 int __cpu_disable(void)
 204 {
 205         unsigned int cpu = smp_processor_id();
 206         int ret;
 207
 208         ret = platform_cpu_disable(cpu);
 209         if (ret)
 210                 return ret;
 211
 212         /*
 213          * Take this CPU offline.  Once we clear this, we can't return,
 214          * and we must not schedule until we're ready to give up the cpu.
 215          */
 216         set_cpu_online(cpu, false);
 217
 218         /*
 219          * OK - migrate IRQs away from this CPU
 220          */
 221         migrate_irqs();
 222
 223         /*
 224          * Flush user cache and TLB mappings, and then remove this CPU
 225          * from the vm mask set of all processes.
 226          *
 227          * Caches are flushed to the Level of Unification Inner Shareable
 228          * to write-back dirty lines to unified caches shared by all CPUs.
 229          */
 230         flush_cache_louis();
 231         local_flush_tlb_all();
 232
 233         return 0;
 234 }
 235
 236 static DECLARE_COMPLETION(cpu_died);
 237
 238 /*
 239  * called on the thread which is asking for a CPU to be shutdown -
 240  * waits until shutdown has completed, or it is timed out.
 241  */
 242 void __cpu_die(unsigned int cpu)
 243 {
 244         if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
 245                 pr_err("CPU%u: cpu didn't die\n", cpu);
 246                 return;
 247         }
 248
 249         clear_tasks_mm_cpumask(cpu);
 250
 251         pr_notice("CPU%u: shutdown\n", cpu);
 252
 253         /*
 254          * platform_cpu_kill() is generally expected to do the powering off
 255          * and/or cutting of clocks to the dying CPU.  Optionally, this may
 256          * be done by the CPU which is dying in preference to supporting
 257          * this call, but that means there is _no_ synchronisation between
 258          * the requesting CPU and the dying CPU actually losing power.
 259          */
 260         if (!platform_cpu_kill(cpu))
 261                 pr_err("CPU%u: unable to kill\n", cpu);
 262 }
 263
 264 /*
 265  * Called from the idle thread for the CPU which has been shutdown.
 266  *
 267  * Note that we disable IRQs here, but do not re-enable them
 268  * before returning to the caller. This is also the behaviour
 269  * of the other hotplug-cpu capable cores, so presumably coming
 270  * out of idle fixes this.
 271  */
 272 void arch_cpu_idle_dead(void)
 273 {
 274         unsigned int cpu = smp_processor_id();
 275
 276         idle_task_exit();
 277
 278         local_irq_disable();
 279
 280         /*
 281          * Flush the data out of the L1 cache for this CPU.  This must be
 282          * before the completion to ensure that data is safely written out
 283          * before platform_cpu_kill() gets called - which may disable
 284          * *this* CPU and power down its cache.
 285          */
 286         flush_cache_louis();
 287
 288         /*
 289          * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
 290          * this returns, power and/or clocks can be removed at any point
 291          * from this CPU and its cache by platform_cpu_kill().
 292          */
 293         complete(&cpu_died);
 294
 295         /*
 296          * Ensure that the cache lines associated with that completion are
 297          * written out.  This covers the case where _this_ CPU is doing the
 298          * powering down, to ensure that the completion is visible to the
 299          * CPU waiting for this one.
 300          */
 301         flush_cache_louis();
 302
 303         /*
 304          * The actual CPU shutdown procedure is at least platform (if not
 305          * CPU) specific.  This may remove power, or it may simply spin.
 306          *
 307          * Platforms are generally expected *NOT* to return from this call,
 308          * although there are some which do because they have no way to
 309          * power down the CPU.  These platforms are the _only_ reason we
 310          * have a return path which uses the fragment of assembly below.
 311          *
 312          * The return path should not be used for platforms which can
 313          * power off the CPU.
 314          */
 315         if (smp_ops.cpu_die)
 316                 smp_ops.cpu_die(cpu);
 317
 318         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 319                 cpu);
 320
 321         /*
 322          * Do not return to the idle loop - jump back to the secondary
 323          * cpu initialisation.  There's some initialisation which needs
 324          * to be repeated to undo the effects of taking the CPU offline.
 325          */
 326         __asm__("mov    sp, %0\n"
 327         "       mov     fp, #0\n"
 328         "       b       secondary_start_kernel"
 329                 :
 330                 : "r" (task_stack_page(current) + THREAD_SIZE - 8));
 331 }
 332 #endif /* CONFIG_HOTPLUG_CPU */
 333
 334 /*
 335  * Called by both boot and secondaries to move global data into
 336  * per-processor storage.
 337  */
 338 static void smp_store_cpu_info(unsigned int cpuid)
 339 {
 340         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 341
 342         cpu_info->loops_per_jiffy = loops_per_jiffy;
 343         cpu_info->cpuid = read_cpuid_id();
 344
 345         store_cpu_topology(cpuid);
 346 }
 347
 348 /*
 349  * This is the secondary CPU boot entry.  We're using this CPUs
 350  * idle thread stack, but a set of temporary page tables.
 351  */
 352 asmlinkage void secondary_start_kernel(void)
 353 {
 354         struct mm_struct *mm = &init_mm;
 355         unsigned int cpu;
 356
 357         /*
 358          * The identity mapping is uncached (strongly ordered), so
 359          * switch away from it before attempting any exclusive accesses.
 360          */
 361         cpu_switch_mm(mm->pgd, mm);
 362         local_flush_bp_all();
 363         enter_lazy_tlb(mm, current);
 364         local_flush_tlb_all();
 365
 366         /*
 367          * All kernel threads share the same mm context; grab a
 368          * reference and switch to it.
 369          */
 370         cpu = smp_processor_id();
 371         atomic_inc(&mm->mm_count);
 372         current->active_mm = mm;
 373         cpumask_set_cpu(cpu, mm_cpumask(mm));
 374
 375         cpu_init();
 376
 377         pr_debug("CPU%u: Booted secondary processor\n", cpu);
 378
 379         preempt_disable();
 380         trace_hardirqs_off();
 381
 382         /*
 383          * Give the platform a chance to do its own initialisation.
 384          */
 385         if (smp_ops.smp_secondary_init)
 386                 smp_ops.smp_secondary_init(cpu);
 387
 388         notify_cpu_starting(cpu);
 389
 390         calibrate_delay();
 391
 392         smp_store_cpu_info(cpu);
 393
 394         /*
 395          * OK, now it's safe to let the boot CPU continue.  Wait for
 396          * the CPU migration code to notice that the CPU is online
 397          * before we continue - which happens after __cpu_up returns.
 398          */
 399         set_cpu_online(cpu, true);
 400         complete(&cpu_running);
 401
 402         local_irq_enable();
 403         local_fiq_enable();
 404         local_abt_enable();
 405
 406         /*
 407          * OK, it's off to the idle thread for us
 408          */
 409         cpu_startup_entry(CPUHP_ONLINE);
 410 }
 411
 412 void __init smp_cpus_done(unsigned int max_cpus)
 413 {
 414         int cpu;
 415         unsigned long bogosum = 0;
 416
 417         for_each_online_cpu(cpu)
 418                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 419
 420         printk(KERN_INFO "SMP: Total of %d processors activated "
 421                "(%lu.%02lu BogoMIPS).\n",
 422                num_online_cpus(),
 423                bogosum / (500000/HZ),
 424                (bogosum / (5000/HZ)) % 100);
 425
 426         hyp_mode_check();
 427 }
 428
 429 void __init smp_prepare_boot_cpu(void)
 430 {
 431         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 432 }
 433
 434 void __init smp_prepare_cpus(unsigned int max_cpus)
 435 {
 436         unsigned int ncores = num_possible_cpus();
 437
 438         init_cpu_topology();
 439
 440         smp_store_cpu_info(smp_processor_id());
 441
 442         /*
 443          * are we trying to boot more cores than exist?
 444          */
 445         if (max_cpus > ncores)
 446                 max_cpus = ncores;
 447         if (ncores > 1 && max_cpus) {
 448                 /*
 449                  * Initialise the present map, which describes the set of CPUs
 450                  * actually populated at the present time. A platform should
 451                  * re-initialize the map in the platforms smp_prepare_cpus()
 452                  * if present != possible (e.g. physical hotplug).
 453                  */
 454                 init_cpu_present(cpu_possible_mask);
 455
 456                 /*
 457                  * Initialise the SCU if there are more than one CPU
 458                  * and let them know where to start.
 459                  */
 460                 if (smp_ops.smp_prepare_cpus)
 461                         smp_ops.smp_prepare_cpus(max_cpus);
 462         }
 463 }
 464
 465 static void (*__smp_cross_call)(const struct cpumask *, unsigned int);
 466
 467 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
 468 {
 469         if (!__smp_cross_call)
 470                 __smp_cross_call = fn;
 471 }
 472
 473 static const char *ipi_types[NR_IPI] __tracepoint_string = {
 474 #define S(x,s)  [x] = s
 475         S(IPI_WAKEUP, "CPU wakeup interrupts"),
 476         S(IPI_TIMER, "Timer broadcast interrupts"),
 477         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
 478         S(IPI_CALL_FUNC, "Function call interrupts"),
 479         S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
 480         S(IPI_CPU_STOP, "CPU stop interrupts"),
 481         S(IPI_IRQ_WORK, "IRQ work interrupts"),
 482         S(IPI_COMPLETION, "completion interrupts"),
 483 };
 484
 485 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 486 {
 487         trace_ipi_raise(target, ipi_types[ipinr]);
 488         __smp_cross_call(target, ipinr);
 489 }
 490
 491 void show_ipi_list(struct seq_file *p, int prec)
 492 {
 493         unsigned int cpu, i;
 494
 495         for (i = 0; i < NR_IPI; i++) {
 496                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 497
 498                 for_each_online_cpu(cpu)
 499                         seq_printf(p, "%10u ",
 500                                    __get_irq_stat(cpu, ipi_irqs[i]));
 501
 502                 seq_printf(p, " %s\n", ipi_types[i]);
 503         }
 504 }
 505
 506 u64 smp_irq_stat_cpu(unsigned int cpu)
 507 {
 508         u64 sum = 0;
 509         int i;
 510
 511         for (i = 0; i < NR_IPI; i++)
 512                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
 513
 514         return sum;
 515 }
 516
 517 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 518 {
 519         smp_cross_call(mask, IPI_CALL_FUNC);
 520 }
 521
 522 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 523 {
 524         smp_cross_call(mask, IPI_WAKEUP);
 525 }
 526
 527 void arch_send_call_function_single_ipi(int cpu)
 528 {
 529         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 530 }
 531
 532 #ifdef CONFIG_IRQ_WORK
 533 void arch_irq_work_raise(void)
 534 {
 535         if (arch_irq_work_has_interrupt())
 536                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 537 }
 538 #endif
 539
 540 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 541 void tick_broadcast(const struct cpumask *mask)
 542 {
 543         smp_cross_call(mask, IPI_TIMER);
 544 }
 545 #endif
 546
 547 static DEFINE_RAW_SPINLOCK(stop_lock);
 548
 549 /*
 550  * ipi_cpu_stop - handle IPI from smp_send_stop()
 551  */
 552 static void ipi_cpu_stop(unsigned int cpu)
 553 {
 554         if (system_state == SYSTEM_BOOTING ||
 555             system_state == SYSTEM_RUNNING) {
 556                 raw_spin_lock(&stop_lock);
 557                 pr_crit("CPU%u: stopping\n", cpu);
 558                 dump_stack();
 559                 raw_spin_unlock(&stop_lock);
 560         }
 561
 562         set_cpu_online(cpu, false);
 563
 564         local_fiq_disable();
 565         local_irq_disable();
 566
 567         while (1)
 568                 cpu_relax();
 569 }
 570
 571 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 572
 573 int register_ipi_completion(struct completion *completion, int cpu)
 574 {
 575         per_cpu(cpu_completion, cpu) = completion;
 576         return IPI_COMPLETION;
 577 }
 578
 579 static void ipi_complete(unsigned int cpu)
 580 {
 581         complete(per_cpu(cpu_completion, cpu));
 582 }
 583
 584 /*
 585  * Main handler for inter-processor interrupts
 586  */
 587 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 588 {
 589         handle_IPI(ipinr, regs);
 590 }
 591
 592 void handle_IPI(int ipinr, struct pt_regs *regs)
 593 {
 594         unsigned int cpu = smp_processor_id();
 595         struct pt_regs *old_regs = set_irq_regs(regs);
 596
 597         if ((unsigned)ipinr < NR_IPI) {
 598                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 599                 __inc_irq_stat(cpu, ipi_irqs[ipinr]);
 600         }
 601
 602         switch (ipinr) {
 603         case IPI_WAKEUP:
 604                 break;
 605
 606 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 607         case IPI_TIMER:
 608                 irq_enter();
 609                 tick_receive_broadcast();
 610                 irq_exit();
 611                 break;
 612 #endif
 613
 614         case IPI_RESCHEDULE:
 615                 scheduler_ipi();
 616                 break;
 617
 618         case IPI_CALL_FUNC:
 619                 irq_enter();
 620                 generic_smp_call_function_interrupt();
 621                 irq_exit();
 622                 break;
 623
 624         case IPI_CALL_FUNC_SINGLE:
 625                 irq_enter();
 626                 generic_smp_call_function_single_interrupt();
 627                 irq_exit();
 628                 break;
 629
 630         case IPI_CPU_STOP:
 631                 irq_enter();
 632                 ipi_cpu_stop(cpu);
 633                 irq_exit();
 634                 break;
 635
 636 #ifdef CONFIG_IRQ_WORK
 637         case IPI_IRQ_WORK:
 638                 irq_enter();
 639                 irq_work_run();
 640                 irq_exit();
 641                 break;
 642 #endif
 643
 644         case IPI_COMPLETION:
 645                 irq_enter();
 646                 ipi_complete(cpu);
 647                 irq_exit();
 648                 break;
 649
 650         case IPI_CPU_BACKTRACE:
 651                 irq_enter();
 652                 nmi_cpu_backtrace(regs);
 653                 irq_exit();
 654                 break;
 655
 656         default:
 657                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 658                         cpu, ipinr);
 659                 break;
 660         }
 661
 662         if ((unsigned)ipinr < NR_IPI)
 663                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 664         set_irq_regs(old_regs);
 665 }
 666
 667 void smp_send_reschedule(int cpu)
 668 {
 669         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 670 }
 671
 672 void smp_send_stop(void)
 673 {
 674         unsigned long timeout;
 675         struct cpumask mask;
 676
 677         cpumask_copy(&mask, cpu_online_mask);
 678         cpumask_clear_cpu(smp_processor_id(), &mask);
 679         if (!cpumask_empty(&mask))
 680                 smp_cross_call(&mask, IPI_CPU_STOP);
 681
 682         /* Wait up to one second for other CPUs to stop */
 683         timeout = USEC_PER_SEC;
 684         while (num_online_cpus() > 1 && timeout--)
 685                 udelay(1);
 686
 687         if (num_online_cpus() > 1)
 688                 pr_warn("SMP: failed to stop secondary CPUs\n");
 689 }
 690
 691 /*
 692  * not supported here
 693  */
 694 int setup_profiling_timer(unsigned int multiplier)
 695 {
 696         return -EINVAL;
 697 }
 698
 699 #ifdef CONFIG_CPU_FREQ
 700
 701 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 702 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 703 static unsigned long global_l_p_j_ref;
 704 static unsigned long global_l_p_j_ref_freq;
 705
 706 static int cpufreq_callback(struct notifier_block *nb,
 707                                         unsigned long val, void *data)
 708 {
 709         struct cpufreq_freqs *freq = data;
 710         int cpu = freq->cpu;
 711
 712         if (freq->flags & CPUFREQ_CONST_LOOPS)
 713                 return NOTIFY_OK;
 714
 715         if (!per_cpu(l_p_j_ref, cpu)) {
 716                 per_cpu(l_p_j_ref, cpu) =
 717                         per_cpu(cpu_data, cpu).loops_per_jiffy;
 718                 per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 719                 if (!global_l_p_j_ref) {
 720                         global_l_p_j_ref = loops_per_jiffy;
 721                         global_l_p_j_ref_freq = freq->old;
 722                 }
 723         }
 724
 725         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 726             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 727                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 728                                                 global_l_p_j_ref_freq,
 729                                                 freq->new);
 730                 per_cpu(cpu_data, cpu).loops_per_jiffy =
 731                         cpufreq_scale(per_cpu(l_p_j_ref, cpu),
 732                                         per_cpu(l_p_j_ref_freq, cpu),
 733                                         freq->new);
 734         }
 735         return NOTIFY_OK;
 736 }
 737
 738 static struct notifier_block cpufreq_notifier = {
 739         .notifier_call  = cpufreq_callback,
 740 };
 741
 742 static int __init register_cpufreq_notifier(void)
 743 {
 744         return cpufreq_register_notifier(&cpufreq_notifier,
 745                                                 CPUFREQ_TRANSITION_NOTIFIER);
 746 }
 747 core_initcall(register_cpufreq_notifier);
 748
 749 #endif
 750
 751 static void raise_nmi(cpumask_t *mask)
 752 {
 753         /*
 754          * Generate the backtrace directly if we are running in a calling
 755          * context that is not preemptible by the backtrace IPI. Note
 756          * that nmi_cpu_backtrace() automatically removes the current cpu
 757          * from mask.
 758          */
 759         if (cpumask_test_cpu(smp_processor_id(), mask) && irqs_disabled())
 760                 nmi_cpu_backtrace(NULL);
 761
 762         smp_cross_call(mask, IPI_CPU_BACKTRACE);
 763 }
 764
 765 void arch_trigger_all_cpu_backtrace(bool include_self)
 766 {
 767         nmi_trigger_all_cpu_backtrace(include_self, raise_nmi);
 768 }