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