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/mm.h>
  15 #include <linux/sched/hotplug.h>
  16 #include <linux/sched/task_stack.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/cache.h>
  19 #include <linux/profile.h>
  20 #include <linux/errno.h>
  21 #include <linux/mm.h>
  22 #include <linux/err.h>
  23 #include <linux/cpu.h>
  24 #include <linux/seq_file.h>
  25 #include <linux/irq.h>
  26 #include <linux/nmi.h>
  27 #include <linux/percpu.h>
  28 #include <linux/clockchips.h>
  29 #include <linux/completion.h>
  30 #include <linux/cpufreq.h>
  31 #include <linux/irq_work.h>
  32
  33 #include <linux/atomic.h>
  34 #include <asm/bugs.h>
  35 #include <asm/smp.h>
  36 #include <asm/cacheflush.h>
  37 #include <asm/cpu.h>
  38 #include <asm/cputype.h>
  39 #include <asm/exception.h>
  40 #include <asm/idmap.h>
  41 #include <asm/topology.h>
  42 #include <asm/mmu_context.h>
  43 #include <asm/pgtable.h>
  44 #include <asm/pgalloc.h>
  45 #include <asm/procinfo.h>
  46 #include <asm/processor.h>
  47 #include <asm/sections.h>
  48 #include <asm/tlbflush.h>
  49 #include <asm/ptrace.h>
  50 #include <asm/smp_plat.h>
  51 #include <asm/virt.h>
  52 #include <asm/mach/arch.h>
  53 #include <asm/mpu.h>
  54
  55 #define CREATE_TRACE_POINTS
  56 #include <trace/events/ipi.h>
  57
  58 /*
  59  * as from 2.5, kernels no longer have an init_tasks structure
  60  * so we need some other way of telling a new secondary core
  61  * where to place its SVC stack
  62  */
  63 struct secondary_data secondary_data;
  64
  65 enum ipi_msg_type {
  66         IPI_WAKEUP,
  67         IPI_TIMER,
  68         IPI_RESCHEDULE,
  69         IPI_CALL_FUNC,
  70         IPI_CPU_STOP,
  71         IPI_IRQ_WORK,
  72         IPI_COMPLETION,
  73         /*
  74          * CPU_BACKTRACE is special and not included in NR_IPI
  75          * or tracable with trace_ipi_*
  76          */
  77         IPI_CPU_BACKTRACE,
  78         /*
  79          * SGI8-15 can be reserved by secure firmware, and thus may
  80          * not be usable by the kernel. Please keep the above limited
  81          * to at most 8 entries.
  82          */
  83 };
  84
  85 static DECLARE_COMPLETION(cpu_running);
  86
  87 static struct smp_operations smp_ops __ro_after_init;
  88
  89 void __init smp_set_ops(const struct smp_operations *ops)
  90 {
  91         if (ops)
  92                 smp_ops = *ops;
  93 };
  94
  95 static unsigned long get_arch_pgd(pgd_t *pgd)
  96 {
  97 #ifdef CONFIG_ARM_LPAE
  98         return __phys_to_pfn(virt_to_phys(pgd));
  99 #else
 100         return virt_to_phys(pgd);
 101 #endif
 102 }
 103
 104 #if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
 105 static int secondary_biglittle_prepare(unsigned int cpu)
 106 {
 107         if (!cpu_vtable[cpu])
 108                 cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL);
 109
 110         return cpu_vtable[cpu] ? 0 : -ENOMEM;
 111 }
 112
 113 static void secondary_biglittle_init(void)
 114 {
 115         init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
 116 }
 117 #else
 118 static int secondary_biglittle_prepare(unsigned int cpu)
 119 {
 120         return 0;
 121 }
 122
 123 static void secondary_biglittle_init(void)
 124 {
 125 }
 126 #endif
 127
 128 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 129 {
 130         int ret;
 131
 132         if (!smp_ops.smp_boot_secondary)
 133                 return -ENOSYS;
 134
 135         ret = secondary_biglittle_prepare(cpu);
 136         if (ret)
 137                 return ret;
 138
 139         /*
 140          * We need to tell the secondary core where to find
 141          * its stack and the page tables.
 142          */
 143         secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
 144 #ifdef CONFIG_ARM_MPU
 145         secondary_data.mpu_rgn_info = &mpu_rgn_info;
 146 #endif
 147
 148 #ifdef CONFIG_MMU
 149         secondary_data.pgdir = virt_to_phys(idmap_pgd);
 150         secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
 151 #endif
 152         sync_cache_w(&secondary_data);
 153
 154         /*
 155          * Now bring the CPU into our world.
 156          */
 157         ret = smp_ops.smp_boot_secondary(cpu, idle);
 158         if (ret == 0) {
 159                 /*
 160                  * CPU was successfully started, wait for it
 161                  * to come online or time out.
 162                  */
 163                 wait_for_completion_timeout(&cpu_running,
 164                                                  msecs_to_jiffies(1000));
 165
 166                 if (!cpu_online(cpu)) {
 167                         pr_crit("CPU%u: failed to come online\n", cpu);
 168                         ret = -EIO;
 169                 }
 170         } else {
 171                 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
 172         }
 173
 174
 175         memset(&secondary_data, 0, sizeof(secondary_data));
 176         return ret;
 177 }
 178
 179 /* platform specific SMP operations */
 180 void __init smp_init_cpus(void)
 181 {
 182         if (smp_ops.smp_init_cpus)
 183                 smp_ops.smp_init_cpus();
 184 }
 185
 186 int platform_can_secondary_boot(void)
 187 {
 188         return !!smp_ops.smp_boot_secondary;
 189 }
 190
 191 int platform_can_cpu_hotplug(void)
 192 {
 193 #ifdef CONFIG_HOTPLUG_CPU
 194         if (smp_ops.cpu_kill)
 195                 return 1;
 196 #endif
 197
 198         return 0;
 199 }
 200
 201 #ifdef CONFIG_HOTPLUG_CPU
 202 static int platform_cpu_kill(unsigned int cpu)
 203 {
 204         if (smp_ops.cpu_kill)
 205                 return smp_ops.cpu_kill(cpu);
 206         return 1;
 207 }
 208
 209 static int platform_cpu_disable(unsigned int cpu)
 210 {
 211         if (smp_ops.cpu_disable)
 212                 return smp_ops.cpu_disable(cpu);
 213
 214         return 0;
 215 }
 216
 217 int platform_can_hotplug_cpu(unsigned int cpu)
 218 {
 219         /* cpu_die must be specified to support hotplug */
 220         if (!smp_ops.cpu_die)
 221                 return 0;
 222
 223         if (smp_ops.cpu_can_disable)
 224                 return smp_ops.cpu_can_disable(cpu);
 225
 226         /*
 227          * By default, allow disabling all CPUs except the first one,
 228          * since this is special on a lot of platforms, e.g. because
 229          * of clock tick interrupts.
 230          */
 231         return cpu != 0;
 232 }
 233
 234 /*
 235  * __cpu_disable runs on the processor to be shutdown.
 236  */
 237 int __cpu_disable(void)
 238 {
 239         unsigned int cpu = smp_processor_id();
 240         int ret;
 241
 242         ret = platform_cpu_disable(cpu);
 243         if (ret)
 244                 return ret;
 245
 246         /*
 247          * Take this CPU offline.  Once we clear this, we can't return,
 248          * and we must not schedule until we're ready to give up the cpu.
 249          */
 250         set_cpu_online(cpu, false);
 251
 252         /*
 253          * OK - migrate IRQs away from this CPU
 254          */
 255         irq_migrate_all_off_this_cpu();
 256
 257         /*
 258          * Flush user cache and TLB mappings, and then remove this CPU
 259          * from the vm mask set of all processes.
 260          *
 261          * Caches are flushed to the Level of Unification Inner Shareable
 262          * to write-back dirty lines to unified caches shared by all CPUs.
 263          */
 264         flush_cache_louis();
 265         local_flush_tlb_all();
 266
 267         return 0;
 268 }
 269
 270 static DECLARE_COMPLETION(cpu_died);
 271
 272 /*
 273  * called on the thread which is asking for a CPU to be shutdown -
 274  * waits until shutdown has completed, or it is timed out.
 275  */
 276 void __cpu_die(unsigned int cpu)
 277 {
 278         if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
 279                 pr_err("CPU%u: cpu didn't die\n", cpu);
 280                 return;
 281         }
 282         pr_debug("CPU%u: shutdown\n", cpu);
 283
 284         clear_tasks_mm_cpumask(cpu);
 285         /*
 286          * platform_cpu_kill() is generally expected to do the powering off
 287          * and/or cutting of clocks to the dying CPU.  Optionally, this may
 288          * be done by the CPU which is dying in preference to supporting
 289          * this call, but that means there is _no_ synchronisation between
 290          * the requesting CPU and the dying CPU actually losing power.
 291          */
 292         if (!platform_cpu_kill(cpu))
 293                 pr_err("CPU%u: unable to kill\n", cpu);
 294 }
 295
 296 /*
 297  * Called from the idle thread for the CPU which has been shutdown.
 298  *
 299  * Note that we disable IRQs here, but do not re-enable them
 300  * before returning to the caller. This is also the behaviour
 301  * of the other hotplug-cpu capable cores, so presumably coming
 302  * out of idle fixes this.
 303  */
 304 void arch_cpu_idle_dead(void)
 305 {
 306         unsigned int cpu = smp_processor_id();
 307
 308         idle_task_exit();
 309
 310         local_irq_disable();
 311
 312         /*
 313          * Flush the data out of the L1 cache for this CPU.  This must be
 314          * before the completion to ensure that data is safely written out
 315          * before platform_cpu_kill() gets called - which may disable
 316          * *this* CPU and power down its cache.
 317          */
 318         flush_cache_louis();
 319
 320         /*
 321          * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
 322          * this returns, power and/or clocks can be removed at any point
 323          * from this CPU and its cache by platform_cpu_kill().
 324          */
 325         complete(&cpu_died);
 326
 327         /*
 328          * Ensure that the cache lines associated with that completion are
 329          * written out.  This covers the case where _this_ CPU is doing the
 330          * powering down, to ensure that the completion is visible to the
 331          * CPU waiting for this one.
 332          */
 333         flush_cache_louis();
 334
 335         /*
 336          * The actual CPU shutdown procedure is at least platform (if not
 337          * CPU) specific.  This may remove power, or it may simply spin.
 338          *
 339          * Platforms are generally expected *NOT* to return from this call,
 340          * although there are some which do because they have no way to
 341          * power down the CPU.  These platforms are the _only_ reason we
 342          * have a return path which uses the fragment of assembly below.
 343          *
 344          * The return path should not be used for platforms which can
 345          * power off the CPU.
 346          */
 347         if (smp_ops.cpu_die)
 348                 smp_ops.cpu_die(cpu);
 349
 350         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 351                 cpu);
 352
 353         /*
 354          * Do not return to the idle loop - jump back to the secondary
 355          * cpu initialisation.  There's some initialisation which needs
 356          * to be repeated to undo the effects of taking the CPU offline.
 357          */
 358         __asm__("mov    sp, %0\n"
 359         "       mov     fp, #0\n"
 360         "       b       secondary_start_kernel"
 361                 :
 362                 : "r" (task_stack_page(current) + THREAD_SIZE - 8));
 363 }
 364 #endif /* CONFIG_HOTPLUG_CPU */
 365
 366 /*
 367  * Called by both boot and secondaries to move global data into
 368  * per-processor storage.
 369  */
 370 static void smp_store_cpu_info(unsigned int cpuid)
 371 {
 372         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 373
 374         cpu_info->loops_per_jiffy = loops_per_jiffy;
 375         cpu_info->cpuid = read_cpuid_id();
 376
 377         store_cpu_topology(cpuid);
 378 }
 379
 380 /*
 381  * This is the secondary CPU boot entry.  We're using this CPUs
 382  * idle thread stack, but a set of temporary page tables.
 383  */
 384 asmlinkage void secondary_start_kernel(void)
 385 {
 386         struct mm_struct *mm = &init_mm;
 387         unsigned int cpu;
 388
 389         secondary_biglittle_init();
 390
 391         /*
 392          * The identity mapping is uncached (strongly ordered), so
 393          * switch away from it before attempting any exclusive accesses.
 394          */
 395         cpu_switch_mm(mm->pgd, mm);
 396         local_flush_bp_all();
 397         enter_lazy_tlb(mm, current);
 398         local_flush_tlb_all();
 399
 400         /*
 401          * All kernel threads share the same mm context; grab a
 402          * reference and switch to it.
 403          */
 404         cpu = smp_processor_id();
 405         mmgrab(mm);
 406         current->active_mm = mm;
 407         cpumask_set_cpu(cpu, mm_cpumask(mm));
 408
 409         cpu_init();
 410
 411 #ifndef CONFIG_MMU
 412         setup_vectors_base();
 413 #endif
 414         pr_debug("CPU%u: Booted secondary processor\n", cpu);
 415
 416         preempt_disable();
 417         trace_hardirqs_off();
 418
 419         /*
 420          * Give the platform a chance to do its own initialisation.
 421          */
 422         if (smp_ops.smp_secondary_init)
 423                 smp_ops.smp_secondary_init(cpu);
 424
 425         notify_cpu_starting(cpu);
 426
 427         calibrate_delay();
 428
 429         smp_store_cpu_info(cpu);
 430
 431         /*
 432          * OK, now it's safe to let the boot CPU continue.  Wait for
 433          * the CPU migration code to notice that the CPU is online
 434          * before we continue - which happens after __cpu_up returns.
 435          */
 436         set_cpu_online(cpu, true);
 437
 438         check_other_bugs();
 439
 440         complete(&cpu_running);
 441
 442         local_irq_enable();
 443         local_fiq_enable();
 444         local_abt_enable();
 445
 446         /*
 447          * OK, it's off to the idle thread for us
 448          */
 449         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 450 }
 451
 452 void __init smp_cpus_done(unsigned int max_cpus)
 453 {
 454         int cpu;
 455         unsigned long bogosum = 0;
 456
 457         for_each_online_cpu(cpu)
 458                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 459
 460         printk(KERN_INFO "SMP: Total of %d processors activated "
 461                "(%lu.%02lu BogoMIPS).\n",
 462                num_online_cpus(),
 463                bogosum / (500000/HZ),
 464                (bogosum / (5000/HZ)) % 100);
 465
 466         hyp_mode_check();
 467 }
 468
 469 void __init smp_prepare_boot_cpu(void)
 470 {
 471         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 472 }
 473
 474 void __init smp_prepare_cpus(unsigned int max_cpus)
 475 {
 476         unsigned int ncores = num_possible_cpus();
 477
 478         init_cpu_topology();
 479
 480         smp_store_cpu_info(smp_processor_id());
 481
 482         /*
 483          * are we trying to boot more cores than exist?
 484          */
 485         if (max_cpus > ncores)
 486                 max_cpus = ncores;
 487         if (ncores > 1 && max_cpus) {
 488                 /*
 489                  * Initialise the present map, which describes the set of CPUs
 490                  * actually populated at the present time. A platform should
 491                  * re-initialize the map in the platforms smp_prepare_cpus()
 492                  * if present != possible (e.g. physical hotplug).
 493                  */
 494                 init_cpu_present(cpu_possible_mask);
 495
 496                 /*
 497                  * Initialise the SCU if there are more than one CPU
 498                  * and let them know where to start.
 499                  */
 500                 if (smp_ops.smp_prepare_cpus)
 501                         smp_ops.smp_prepare_cpus(max_cpus);
 502         }
 503 }
 504
 505 static void (*__smp_cross_call)(const struct cpumask *, unsigned int);
 506
 507 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
 508 {
 509         if (!__smp_cross_call)
 510                 __smp_cross_call = fn;
 511 }
 512
 513 static const char *ipi_types[NR_IPI] __tracepoint_string = {
 514 #define S(x,s)  [x] = s
 515         S(IPI_WAKEUP, "CPU wakeup interrupts"),
 516         S(IPI_TIMER, "Timer broadcast interrupts"),
 517         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
 518         S(IPI_CALL_FUNC, "Function call interrupts"),
 519         S(IPI_CPU_STOP, "CPU stop interrupts"),
 520         S(IPI_IRQ_WORK, "IRQ work interrupts"),
 521         S(IPI_COMPLETION, "completion interrupts"),
 522 };
 523
 524 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 525 {
 526         trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
 527         __smp_cross_call(target, ipinr);
 528 }
 529
 530 void show_ipi_list(struct seq_file *p, int prec)
 531 {
 532         unsigned int cpu, i;
 533
 534         for (i = 0; i < NR_IPI; i++) {
 535                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 536
 537                 for_each_online_cpu(cpu)
 538                         seq_printf(p, "%10u ",
 539                                    __get_irq_stat(cpu, ipi_irqs[i]));
 540
 541                 seq_printf(p, " %s\n", ipi_types[i]);
 542         }
 543 }
 544
 545 u64 smp_irq_stat_cpu(unsigned int cpu)
 546 {
 547         u64 sum = 0;
 548         int i;
 549
 550         for (i = 0; i < NR_IPI; i++)
 551                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
 552
 553         return sum;
 554 }
 555
 556 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 557 {
 558         smp_cross_call(mask, IPI_CALL_FUNC);
 559 }
 560
 561 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 562 {
 563         smp_cross_call(mask, IPI_WAKEUP);
 564 }
 565
 566 void arch_send_call_function_single_ipi(int cpu)
 567 {
 568         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
 569 }
 570
 571 #ifdef CONFIG_IRQ_WORK
 572 void arch_irq_work_raise(void)
 573 {
 574         if (arch_irq_work_has_interrupt())
 575                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 576 }
 577 #endif
 578
 579 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 580 void tick_broadcast(const struct cpumask *mask)
 581 {
 582         smp_cross_call(mask, IPI_TIMER);
 583 }
 584 #endif
 585
 586 static DEFINE_RAW_SPINLOCK(stop_lock);
 587
 588 /*
 589  * ipi_cpu_stop - handle IPI from smp_send_stop()
 590  */
 591 static void ipi_cpu_stop(unsigned int cpu)
 592 {
 593         if (system_state <= SYSTEM_RUNNING) {
 594                 raw_spin_lock(&stop_lock);
 595                 pr_crit("CPU%u: stopping\n", cpu);
 596                 dump_stack();
 597                 raw_spin_unlock(&stop_lock);
 598         }
 599
 600         set_cpu_online(cpu, false);
 601
 602         local_fiq_disable();
 603         local_irq_disable();
 604
 605         while (1) {
 606                 cpu_relax();
 607                 wfe();
 608         }
 609 }
 610
 611 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 612
 613 int register_ipi_completion(struct completion *completion, int cpu)
 614 {
 615         per_cpu(cpu_completion, cpu) = completion;
 616         return IPI_COMPLETION;
 617 }
 618
 619 static void ipi_complete(unsigned int cpu)
 620 {
 621         complete(per_cpu(cpu_completion, cpu));
 622 }
 623
 624 /*
 625  * Main handler for inter-processor interrupts
 626  */
 627 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 628 {
 629         handle_IPI(ipinr, regs);
 630 }
 631
 632 void handle_IPI(int ipinr, struct pt_regs *regs)
 633 {
 634         unsigned int cpu = smp_processor_id();
 635         struct pt_regs *old_regs = set_irq_regs(regs);
 636
 637         if ((unsigned)ipinr < NR_IPI) {
 638                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 639                 __inc_irq_stat(cpu, ipi_irqs[ipinr]);
 640         }
 641
 642         switch (ipinr) {
 643         case IPI_WAKEUP:
 644                 break;
 645
 646 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 647         case IPI_TIMER:
 648                 irq_enter();
 649                 tick_receive_broadcast();
 650                 irq_exit();
 651                 break;
 652 #endif
 653
 654         case IPI_RESCHEDULE:
 655                 scheduler_ipi();
 656                 break;
 657
 658         case IPI_CALL_FUNC:
 659                 irq_enter();
 660                 generic_smp_call_function_interrupt();
 661                 irq_exit();
 662                 break;
 663
 664         case IPI_CPU_STOP:
 665                 irq_enter();
 666                 ipi_cpu_stop(cpu);
 667                 irq_exit();
 668                 break;
 669
 670 #ifdef CONFIG_IRQ_WORK
 671         case IPI_IRQ_WORK:
 672                 irq_enter();
 673                 irq_work_run();
 674                 irq_exit();
 675                 break;
 676 #endif
 677
 678         case IPI_COMPLETION:
 679                 irq_enter();
 680                 ipi_complete(cpu);
 681                 irq_exit();
 682                 break;
 683
 684         case IPI_CPU_BACKTRACE:
 685                 printk_nmi_enter();
 686                 irq_enter();
 687                 nmi_cpu_backtrace(regs);
 688                 irq_exit();
 689                 printk_nmi_exit();
 690                 break;
 691
 692         default:
 693                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 694                         cpu, ipinr);
 695                 break;
 696         }
 697
 698         if ((unsigned)ipinr < NR_IPI)
 699                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 700         set_irq_regs(old_regs);
 701 }
 702
 703 void smp_send_reschedule(int cpu)
 704 {
 705         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 706 }
 707
 708 void smp_send_stop(void)
 709 {
 710         unsigned long timeout;
 711         struct cpumask mask;
 712
 713         cpumask_copy(&mask, cpu_online_mask);
 714         cpumask_clear_cpu(smp_processor_id(), &mask);
 715         if (!cpumask_empty(&mask))
 716                 smp_cross_call(&mask, IPI_CPU_STOP);
 717
 718         /* Wait up to one second for other CPUs to stop */
 719         timeout = USEC_PER_SEC;
 720         while (num_online_cpus() > 1 && timeout--)
 721                 udelay(1);
 722
 723         if (num_online_cpus() > 1)
 724                 pr_warn("SMP: failed to stop secondary CPUs\n");
 725 }
 726
 727 /* In case panic() and panic() called at the same time on CPU1 and CPU2,
 728  * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
 729  * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
 730  * kdump fails. So split out the panic_smp_self_stop() and add
 731  * set_cpu_online(smp_processor_id(), false).
 732  */
 733 void panic_smp_self_stop(void)
 734 {
 735         pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
 736                  smp_processor_id());
 737         set_cpu_online(smp_processor_id(), false);
 738         while (1)
 739                 cpu_relax();
 740 }
 741
 742 /*
 743  * not supported here
 744  */
 745 int setup_profiling_timer(unsigned int multiplier)
 746 {
 747         return -EINVAL;
 748 }
 749
 750 #ifdef CONFIG_CPU_FREQ
 751
 752 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 753 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 754 static unsigned long global_l_p_j_ref;
 755 static unsigned long global_l_p_j_ref_freq;
 756
 757 static int cpufreq_callback(struct notifier_block *nb,
 758                                         unsigned long val, void *data)
 759 {
 760         struct cpufreq_freqs *freq = data;
 761         struct cpumask *cpus = freq->policy->cpus;
 762         int cpu, first = cpumask_first(cpus);
 763         unsigned int lpj;
 764
 765         if (freq->flags & CPUFREQ_CONST_LOOPS)
 766                 return NOTIFY_OK;
 767
 768         if (!per_cpu(l_p_j_ref, first)) {
 769                 for_each_cpu(cpu, cpus) {
 770                         per_cpu(l_p_j_ref, cpu) =
 771                                 per_cpu(cpu_data, cpu).loops_per_jiffy;
 772                         per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 773                 }
 774
 775                 if (!global_l_p_j_ref) {
 776                         global_l_p_j_ref = loops_per_jiffy;
 777                         global_l_p_j_ref_freq = freq->old;
 778                 }
 779         }
 780
 781         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 782             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 783                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 784                                                 global_l_p_j_ref_freq,
 785                                                 freq->new);
 786
 787                 lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
 788                                     per_cpu(l_p_j_ref_freq, first), freq->new);
 789                 for_each_cpu(cpu, cpus)
 790                         per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
 791         }
 792         return NOTIFY_OK;
 793 }
 794
 795 static struct notifier_block cpufreq_notifier = {
 796         .notifier_call  = cpufreq_callback,
 797 };
 798
 799 static int __init register_cpufreq_notifier(void)
 800 {
 801         return cpufreq_register_notifier(&cpufreq_notifier,
 802                                                 CPUFREQ_TRANSITION_NOTIFIER);
 803 }
 804 core_initcall(register_cpufreq_notifier);
 805
 806 #endif
 807
 808 static void raise_nmi(cpumask_t *mask)
 809 {
 810         __smp_cross_call(mask, IPI_CPU_BACKTRACE);
 811 }
 812
 813 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 814 {
 815         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
 816 }