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         clear_tasks_mm_cpumask(cpu);
 234
 235         return 0;
 236 }
 237
 238 static DECLARE_COMPLETION(cpu_died);
 239
 240 /*
 241  * called on the thread which is asking for a CPU to be shutdown -
 242  * waits until shutdown has completed, or it is timed out.
 243  */
 244 void __cpu_die(unsigned int cpu)
 245 {
 246         if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
 247                 pr_err("CPU%u: cpu didn't die\n", cpu);
 248                 return;
 249         }
 250         pr_notice("CPU%u: shutdown\n", cpu);
 251
 252         /*
 253          * platform_cpu_kill() is generally expected to do the powering off
 254          * and/or cutting of clocks to the dying CPU.  Optionally, this may
 255          * be done by the CPU which is dying in preference to supporting
 256          * this call, but that means there is _no_ synchronisation between
 257          * the requesting CPU and the dying CPU actually losing power.
 258          */
 259         if (!platform_cpu_kill(cpu))
 260                 pr_err("CPU%u: unable to kill\n", cpu);
 261 }
 262
 263 /*
 264  * Called from the idle thread for the CPU which has been shutdown.
 265  *
 266  * Note that we disable IRQs here, but do not re-enable them
 267  * before returning to the caller. This is also the behaviour
 268  * of the other hotplug-cpu capable cores, so presumably coming
 269  * out of idle fixes this.
 270  */
 271 void arch_cpu_idle_dead(void)
 272 {
 273         unsigned int cpu = smp_processor_id();
 274
 275         idle_task_exit();
 276
 277         local_irq_disable();
 278
 279         /*
 280          * Flush the data out of the L1 cache for this CPU.  This must be
 281          * before the completion to ensure that data is safely written out
 282          * before platform_cpu_kill() gets called - which may disable
 283          * *this* CPU and power down its cache.
 284          */
 285         flush_cache_louis();
 286
 287         /*
 288          * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
 289          * this returns, power and/or clocks can be removed at any point
 290          * from this CPU and its cache by platform_cpu_kill().
 291          */
 292         complete(&cpu_died);
 293
 294         /*
 295          * Ensure that the cache lines associated with that completion are
 296          * written out.  This covers the case where _this_ CPU is doing the
 297          * powering down, to ensure that the completion is visible to the
 298          * CPU waiting for this one.
 299          */
 300         flush_cache_louis();
 301
 302         /*
 303          * The actual CPU shutdown procedure is at least platform (if not
 304          * CPU) specific.  This may remove power, or it may simply spin.
 305          *
 306          * Platforms are generally expected *NOT* to return from this call,
 307          * although there are some which do because they have no way to
 308          * power down the CPU.  These platforms are the _only_ reason we
 309          * have a return path which uses the fragment of assembly below.
 310          *
 311          * The return path should not be used for platforms which can
 312          * power off the CPU.
 313          */
 314         if (smp_ops.cpu_die)
 315                 smp_ops.cpu_die(cpu);
 316
 317         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 318                 cpu);
 319
 320         /*
 321          * Do not return to the idle loop - jump back to the secondary
 322          * cpu initialisation.  There's some initialisation which needs
 323          * to be repeated to undo the effects of taking the CPU offline.
 324          */
 325         __asm__("mov    sp, %0\n"
 326         "       mov     fp, #0\n"
 327         "       b       secondary_start_kernel"
 328                 :
 329                 : "r" (task_stack_page(current) + THREAD_SIZE - 8));
 330 }
 331 #endif /* CONFIG_HOTPLUG_CPU */
 332
 333 /*
 334  * Called by both boot and secondaries to move global data into
 335  * per-processor storage.
 336  */
 337 static void smp_store_cpu_info(unsigned int cpuid)
 338 {
 339         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 340
 341         cpu_info->loops_per_jiffy = loops_per_jiffy;
 342         cpu_info->cpuid = read_cpuid_id();
 343
 344         store_cpu_topology(cpuid);
 345 }
 346
 347 /*
 348  * This is the secondary CPU boot entry.  We're using this CPUs
 349  * idle thread stack, but a set of temporary page tables.
 350  */
 351 asmlinkage void secondary_start_kernel(void)
 352 {
 353         struct mm_struct *mm = &init_mm;
 354         unsigned int cpu;
 355
 356         /*
 357          * The identity mapping is uncached (strongly ordered), so
 358          * switch away from it before attempting any exclusive accesses.
 359          */
 360         cpu_switch_mm(mm->pgd, mm);
 361         local_flush_bp_all();
 362         enter_lazy_tlb(mm, current);
 363         local_flush_tlb_all();
 364
 365         /*
 366          * All kernel threads share the same mm context; grab a
 367          * reference and switch to it.
 368          */
 369         cpu = smp_processor_id();
 370         atomic_inc(&mm->mm_count);
 371         current->active_mm = mm;
 372         cpumask_set_cpu(cpu, mm_cpumask(mm));
 373
 374         cpu_init();
 375
 376         pr_debug("CPU%u: Booted secondary processor\n", cpu);
 377
 378         preempt_disable();
 379         trace_hardirqs_off();
 380
 381         /*
 382          * Give the platform a chance to do its own initialisation.
 383          */
 384         if (smp_ops.smp_secondary_init)
 385                 smp_ops.smp_secondary_init(cpu);
 386
 387         notify_cpu_starting(cpu);
 388
 389         calibrate_delay();
 390
 391         smp_store_cpu_info(cpu);
 392
 393         /*
 394          * OK, now it's safe to let the boot CPU continue.  Wait for
 395          * the CPU migration code to notice that the CPU is online
 396          * before we continue - which happens after __cpu_up returns.
 397          */
 398         set_cpu_online(cpu, true);
 399         complete(&cpu_running);
 400
 401         local_irq_enable();
 402         local_fiq_enable();
 403         local_abt_enable();
 404
 405         /*
 406          * OK, it's off to the idle thread for us
 407          */
 408         cpu_startup_entry(CPUHP_ONLINE);
 409 }
 410
 411 void __init smp_cpus_done(unsigned int max_cpus)
 412 {
 413         int cpu;
 414         unsigned long bogosum = 0;
 415
 416         for_each_online_cpu(cpu)
 417                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 418
 419         printk(KERN_INFO "SMP: Total of %d processors activated "
 420                "(%lu.%02lu BogoMIPS).\n",
 421                num_online_cpus(),
 422                bogosum / (500000/HZ),
 423                (bogosum / (5000/HZ)) % 100);
 424
 425         hyp_mode_check();
 426 }
 427
 428 void __init smp_prepare_boot_cpu(void)
 429 {
 430         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 431 }
 432
 433 void __init smp_prepare_cpus(unsigned int max_cpus)
 434 {
 435         unsigned int ncores = num_possible_cpus();
 436
 437         init_cpu_topology();
 438
 439         smp_store_cpu_info(smp_processor_id());
 440
 441         /*
 442          * are we trying to boot more cores than exist?
 443          */
 444         if (max_cpus > ncores)
 445                 max_cpus = ncores;
 446         if (ncores > 1 && max_cpus) {
 447                 /*
 448                  * Initialise the present map, which describes the set of CPUs
 449                  * actually populated at the present time. A platform should
 450                  * re-initialize the map in the platforms smp_prepare_cpus()
 451                  * if present != possible (e.g. physical hotplug).
 452                  */
 453                 init_cpu_present(cpu_possible_mask);
 454
 455                 /*
 456                  * Initialise the SCU if there are more than one CPU
 457                  * and let them know where to start.
 458                  */
 459                 if (smp_ops.smp_prepare_cpus)
 460                         smp_ops.smp_prepare_cpus(max_cpus);
 461         }
 462 }
 463
 464 static void (*__smp_cross_call)(const struct cpumask *, unsigned int);
 465
 466 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
 467 {
 468         if (!__smp_cross_call)
 469                 __smp_cross_call = fn;
 470 }
 471
 472 static const char *ipi_types[NR_IPI] __tracepoint_string = {
 473 #define S(x,s)  [x] = s
 474         S(IPI_WAKEUP, "CPU wakeup interrupts"),
 475         S(IPI_TIMER, "Timer broadcast interrupts"),
 476         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
 477         S(IPI_CALL_FUNC, "Function call interrupts"),
 478         S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
 479         S(IPI_CPU_STOP, "CPU stop interrupts"),
 480         S(IPI_IRQ_WORK, "IRQ work interrupts"),
 481         S(IPI_COMPLETION, "completion interrupts"),
 482 };
 483
 484 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 485 {
 486         trace_ipi_raise(target, ipi_types[ipinr]);
 487         __smp_cross_call(target, ipinr);
 488 }
 489
 490 void show_ipi_list(struct seq_file *p, int prec)
 491 {
 492         unsigned int cpu, i;
 493
 494         for (i = 0; i < NR_IPI; i++) {
 495                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 496
 497                 for_each_online_cpu(cpu)
 498                         seq_printf(p, "%10u ",
 499                                    __get_irq_stat(cpu, ipi_irqs[i]));
 500
 501                 seq_printf(p, " %s\n", ipi_types[i]);
 502         }
 503 }
 504
 505 u64 smp_irq_stat_cpu(unsigned int cpu)
 506 {
 507         u64 sum = 0;
 508         int i;
 509
 510         for (i = 0; i < NR_IPI; i++)
 511                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
 512
 513         return sum;
 514 }
 515
 516 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 517 {
 518         smp_cross_call(mask, IPI_CALL_FUNC);
 519 }
 520
 521 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 522 {
 523         smp_cross_call(mask, IPI_WAKEUP);
 524 }
 525
 526 void arch_send_call_function_single_ipi(int cpu)
 527 {
 528         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 529 }
 530
 531 #ifdef CONFIG_IRQ_WORK
 532 void arch_irq_work_raise(void)
 533 {
 534         if (arch_irq_work_has_interrupt())
 535                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 536 }
 537 #endif
 538
 539 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 540 void tick_broadcast(const struct cpumask *mask)
 541 {
 542         smp_cross_call(mask, IPI_TIMER);
 543 }
 544 #endif
 545
 546 static DEFINE_RAW_SPINLOCK(stop_lock);
 547
 548 /*
 549  * ipi_cpu_stop - handle IPI from smp_send_stop()
 550  */
 551 static void ipi_cpu_stop(unsigned int cpu)
 552 {
 553         if (system_state == SYSTEM_BOOTING ||
 554             system_state == SYSTEM_RUNNING) {
 555                 raw_spin_lock(&stop_lock);
 556                 pr_crit("CPU%u: stopping\n", cpu);
 557                 dump_stack();
 558                 raw_spin_unlock(&stop_lock);
 559         }
 560
 561         set_cpu_online(cpu, false);
 562
 563         local_fiq_disable();
 564         local_irq_disable();
 565
 566         while (1)
 567                 cpu_relax();
 568 }
 569
 570 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 571
 572 int register_ipi_completion(struct completion *completion, int cpu)
 573 {
 574         per_cpu(cpu_completion, cpu) = completion;
 575         return IPI_COMPLETION;
 576 }
 577
 578 static void ipi_complete(unsigned int cpu)
 579 {
 580         complete(per_cpu(cpu_completion, cpu));
 581 }
 582
 583 /*
 584  * Main handler for inter-processor interrupts
 585  */
 586 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 587 {
 588         handle_IPI(ipinr, regs);
 589 }
 590
 591 void handle_IPI(int ipinr, struct pt_regs *regs)
 592 {
 593         unsigned int cpu = smp_processor_id();
 594         struct pt_regs *old_regs = set_irq_regs(regs);
 595
 596         if ((unsigned)ipinr < NR_IPI) {
 597                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 598                 __inc_irq_stat(cpu, ipi_irqs[ipinr]);
 599         }
 600
 601         switch (ipinr) {
 602         case IPI_WAKEUP:
 603                 break;
 604
 605 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 606         case IPI_TIMER:
 607                 irq_enter();
 608                 tick_receive_broadcast();
 609                 irq_exit();
 610                 break;
 611 #endif
 612
 613         case IPI_RESCHEDULE:
 614                 scheduler_ipi();
 615                 break;
 616
 617         case IPI_CALL_FUNC:
 618                 irq_enter();
 619                 generic_smp_call_function_interrupt();
 620                 irq_exit();
 621                 break;
 622
 623         case IPI_CALL_FUNC_SINGLE:
 624                 irq_enter();
 625                 generic_smp_call_function_single_interrupt();
 626                 irq_exit();
 627                 break;
 628
 629         case IPI_CPU_STOP:
 630                 irq_enter();
 631                 ipi_cpu_stop(cpu);
 632                 irq_exit();
 633                 break;
 634
 635 #ifdef CONFIG_IRQ_WORK
 636         case IPI_IRQ_WORK:
 637                 irq_enter();
 638                 irq_work_run();
 639                 irq_exit();
 640                 break;
 641 #endif
 642
 643         case IPI_COMPLETION:
 644                 irq_enter();
 645                 ipi_complete(cpu);
 646                 irq_exit();
 647                 break;
 648
 649         case IPI_CPU_BACKTRACE:
 650                 irq_enter();
 651                 nmi_cpu_backtrace(regs);
 652                 irq_exit();
 653                 break;
 654
 655         default:
 656                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 657                         cpu, ipinr);
 658                 break;
 659         }
 660
 661         if ((unsigned)ipinr < NR_IPI)
 662                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 663         set_irq_regs(old_regs);
 664 }
 665
 666 void smp_send_reschedule(int cpu)
 667 {
 668         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 669 }
 670
 671 void smp_send_stop(void)
 672 {
 673         unsigned long timeout;
 674         struct cpumask mask;
 675
 676         cpumask_copy(&mask, cpu_online_mask);
 677         cpumask_clear_cpu(smp_processor_id(), &mask);
 678         if (!cpumask_empty(&mask))
 679                 smp_cross_call(&mask, IPI_CPU_STOP);
 680
 681         /* Wait up to one second for other CPUs to stop */
 682         timeout = USEC_PER_SEC;
 683         while (num_online_cpus() > 1 && timeout--)
 684                 udelay(1);
 685
 686         if (num_online_cpus() > 1)
 687                 pr_warn("SMP: failed to stop secondary CPUs\n");
 688 }
 689
 690 /*
 691  * not supported here
 692  */
 693 int setup_profiling_timer(unsigned int multiplier)
 694 {
 695         return -EINVAL;
 696 }
 697
 698 #ifdef CONFIG_CPU_FREQ
 699
 700 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 701 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 702 static unsigned long global_l_p_j_ref;
 703 static unsigned long global_l_p_j_ref_freq;
 704
 705 static int cpufreq_callback(struct notifier_block *nb,
 706                                         unsigned long val, void *data)
 707 {
 708         struct cpufreq_freqs *freq = data;
 709         int cpu = freq->cpu;
 710
 711         if (freq->flags & CPUFREQ_CONST_LOOPS)
 712                 return NOTIFY_OK;
 713
 714         if (!per_cpu(l_p_j_ref, cpu)) {
 715                 per_cpu(l_p_j_ref, cpu) =
 716                         per_cpu(cpu_data, cpu).loops_per_jiffy;
 717                 per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 718                 if (!global_l_p_j_ref) {
 719                         global_l_p_j_ref = loops_per_jiffy;
 720                         global_l_p_j_ref_freq = freq->old;
 721                 }
 722         }
 723
 724         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 725             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 726                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 727                                                 global_l_p_j_ref_freq,
 728                                                 freq->new);
 729                 per_cpu(cpu_data, cpu).loops_per_jiffy =
 730                         cpufreq_scale(per_cpu(l_p_j_ref, cpu),
 731                                         per_cpu(l_p_j_ref_freq, cpu),
 732                                         freq->new);
 733         }
 734         return NOTIFY_OK;
 735 }
 736
 737 static struct notifier_block cpufreq_notifier = {
 738         .notifier_call  = cpufreq_callback,
 739 };
 740
 741 static int __init register_cpufreq_notifier(void)
 742 {
 743         return cpufreq_register_notifier(&cpufreq_notifier,
 744                                                 CPUFREQ_TRANSITION_NOTIFIER);
 745 }
 746 core_initcall(register_cpufreq_notifier);
 747
 748 #endif
 749
 750 static void raise_nmi(cpumask_t *mask)
 751 {
 752         /*
 753          * Generate the backtrace directly if we are running in a calling
 754          * context that is not preemptible by the backtrace IPI. Note
 755          * that nmi_cpu_backtrace() automatically removes the current cpu
 756          * from mask.
 757          */
 758         if (cpumask_test_cpu(smp_processor_id(), mask) && irqs_disabled())
 759                 nmi_cpu_backtrace(NULL);
 760
 761         smp_cross_call(mask, IPI_CPU_BACKTRACE);
 762 }
 763
 764 void arch_trigger_all_cpu_backtrace(bool include_self)
 765 {
 766         nmi_trigger_all_cpu_backtrace(include_self, raise_nmi);
 767 }