arch/arm/kernel/smp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/arch/arm/kernel/smp.c
   4  *
   5  *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
   6  */
   7 #include <linux/module.h>
   8 #include <linux/delay.h>
   9 #include <linux/init.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/sched/mm.h>
  12 #include <linux/sched/hotplug.h>
  13 #include <linux/sched/task_stack.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/cache.h>
  16 #include <linux/profile.h>
  17 #include <linux/errno.h>
  18 #include <linux/mm.h>
  19 #include <linux/err.h>
  20 #include <linux/cpu.h>
  21 #include <linux/seq_file.h>
  22 #include <linux/irq.h>
  23 #include <linux/nmi.h>
  24 #include <linux/percpu.h>
  25 #include <linux/clockchips.h>
  26 #include <linux/completion.h>
  27 #include <linux/cpufreq.h>
  28 #include <linux/irq_work.h>
  29
  30 #include <linux/atomic.h>
  31 #include <asm/bugs.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/procinfo.h>
  43 #include <asm/processor.h>
  44 #include <asm/sections.h>
  45 #include <asm/tlbflush.h>
  46 #include <asm/ptrace.h>
  47 #include <asm/smp_plat.h>
  48 #include <asm/virt.h>
  49 #include <asm/mach/arch.h>
  50 #include <asm/mpu.h>
  51
  52 #define CREATE_TRACE_POINTS
  53 #include <trace/events/ipi.h>
  54
  55 /*
  56  * as from 2.5, kernels no longer have an init_tasks structure
  57  * so we need some other way of telling a new secondary core
  58  * where to place its SVC stack
  59  */
  60 struct secondary_data secondary_data;
  61
  62 enum ipi_msg_type {
  63         IPI_WAKEUP,
  64         IPI_TIMER,
  65         IPI_RESCHEDULE,
  66         IPI_CALL_FUNC,
  67         IPI_CPU_STOP,
  68         IPI_IRQ_WORK,
  69         IPI_COMPLETION,
  70         /*
  71          * CPU_BACKTRACE is special and not included in NR_IPI
  72          * or tracable with trace_ipi_*
  73          */
  74         IPI_CPU_BACKTRACE,
  75         /*
  76          * SGI8-15 can be reserved by secure firmware, and thus may
  77          * not be usable by the kernel. Please keep the above limited
  78          * to at most 8 entries.
  79          */
  80 };
  81
  82 static DECLARE_COMPLETION(cpu_running);
  83
  84 static struct smp_operations smp_ops __ro_after_init;
  85
  86 void __init smp_set_ops(const struct smp_operations *ops)
  87 {
  88         if (ops)
  89                 smp_ops = *ops;
  90 };
  91
  92 static unsigned long get_arch_pgd(pgd_t *pgd)
  93 {
  94 #ifdef CONFIG_ARM_LPAE
  95         return __phys_to_pfn(virt_to_phys(pgd));
  96 #else
  97         return virt_to_phys(pgd);
  98 #endif
  99 }
 100
 101 #if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
 102 static int secondary_biglittle_prepare(unsigned int cpu)
 103 {
 104         if (!cpu_vtable[cpu])
 105                 cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL);
 106
 107         return cpu_vtable[cpu] ? 0 : -ENOMEM;
 108 }
 109
 110 static void secondary_biglittle_init(void)
 111 {
 112         init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
 113 }
 114 #else
 115 static int secondary_biglittle_prepare(unsigned int cpu)
 116 {
 117         return 0;
 118 }
 119
 120 static void secondary_biglittle_init(void)
 121 {
 122 }
 123 #endif
 124
 125 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 126 {
 127         int ret;
 128
 129         if (!smp_ops.smp_boot_secondary)
 130                 return -ENOSYS;
 131
 132         ret = secondary_biglittle_prepare(cpu);
 133         if (ret)
 134                 return ret;
 135
 136         /*
 137          * We need to tell the secondary core where to find
 138          * its stack and the page tables.
 139          */
 140         secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
 141 #ifdef CONFIG_ARM_MPU
 142         secondary_data.mpu_rgn_info = &mpu_rgn_info;
 143 #endif
 144
 145 #ifdef CONFIG_MMU
 146         secondary_data.pgdir = virt_to_phys(idmap_pgd);
 147         secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
 148 #endif
 149         sync_cache_w(&secondary_data);
 150
 151         /*
 152          * Now bring the CPU into our world.
 153          */
 154         ret = smp_ops.smp_boot_secondary(cpu, idle);
 155         if (ret == 0) {
 156                 /*
 157                  * CPU was successfully started, wait for it
 158                  * to come online or time out.
 159                  */
 160                 wait_for_completion_timeout(&cpu_running,
 161                                                  msecs_to_jiffies(1000));
 162
 163                 if (!cpu_online(cpu)) {
 164                         pr_crit("CPU%u: failed to come online\n", cpu);
 165                         ret = -EIO;
 166                 }
 167         } else {
 168                 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
 169         }
 170
 171
 172         memset(&secondary_data, 0, sizeof(secondary_data));
 173         return ret;
 174 }
 175
 176 /* platform specific SMP operations */
 177 void __init smp_init_cpus(void)
 178 {
 179         if (smp_ops.smp_init_cpus)
 180                 smp_ops.smp_init_cpus();
 181 }
 182
 183 int platform_can_secondary_boot(void)
 184 {
 185         return !!smp_ops.smp_boot_secondary;
 186 }
 187
 188 int platform_can_cpu_hotplug(void)
 189 {
 190 #ifdef CONFIG_HOTPLUG_CPU
 191         if (smp_ops.cpu_kill)
 192                 return 1;
 193 #endif
 194
 195         return 0;
 196 }
 197
 198 #ifdef CONFIG_HOTPLUG_CPU
 199 static int platform_cpu_kill(unsigned int cpu)
 200 {
 201         if (smp_ops.cpu_kill)
 202                 return smp_ops.cpu_kill(cpu);
 203         return 1;
 204 }
 205
 206 static int platform_cpu_disable(unsigned int cpu)
 207 {
 208         if (smp_ops.cpu_disable)
 209                 return smp_ops.cpu_disable(cpu);
 210
 211         return 0;
 212 }
 213
 214 int platform_can_hotplug_cpu(unsigned int cpu)
 215 {
 216         /* cpu_die must be specified to support hotplug */
 217         if (!smp_ops.cpu_die)
 218                 return 0;
 219
 220         if (smp_ops.cpu_can_disable)
 221                 return smp_ops.cpu_can_disable(cpu);
 222
 223         /*
 224          * By default, allow disabling all CPUs except the first one,
 225          * since this is special on a lot of platforms, e.g. because
 226          * of clock tick interrupts.
 227          */
 228         return cpu != 0;
 229 }
 230
 231 /*
 232  * __cpu_disable runs on the processor to be shutdown.
 233  */
 234 int __cpu_disable(void)
 235 {
 236         unsigned int cpu = smp_processor_id();
 237         int ret;
 238
 239         ret = platform_cpu_disable(cpu);
 240         if (ret)
 241                 return ret;
 242
 243         /*
 244          * Take this CPU offline.  Once we clear this, we can't return,
 245          * and we must not schedule until we're ready to give up the cpu.
 246          */
 247         set_cpu_online(cpu, false);
 248
 249         /*
 250          * OK - migrate IRQs away from this CPU
 251          */
 252         irq_migrate_all_off_this_cpu();
 253
 254         /*
 255          * Flush user cache and TLB mappings, and then remove this CPU
 256          * from the vm mask set of all processes.
 257          *
 258          * Caches are flushed to the Level of Unification Inner Shareable
 259          * to write-back dirty lines to unified caches shared by all CPUs.
 260          */
 261         flush_cache_louis();
 262         local_flush_tlb_all();
 263
 264         return 0;
 265 }
 266
 267 static DECLARE_COMPLETION(cpu_died);
 268
 269 /*
 270  * called on the thread which is asking for a CPU to be shutdown -
 271  * waits until shutdown has completed, or it is timed out.
 272  */
 273 void __cpu_die(unsigned int cpu)
 274 {
 275         if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
 276                 pr_err("CPU%u: cpu didn't die\n", cpu);
 277                 return;
 278         }
 279         pr_debug("CPU%u: shutdown\n", cpu);
 280
 281         clear_tasks_mm_cpumask(cpu);
 282         /*
 283          * platform_cpu_kill() is generally expected to do the powering off
 284          * and/or cutting of clocks to the dying CPU.  Optionally, this may
 285          * be done by the CPU which is dying in preference to supporting
 286          * this call, but that means there is _no_ synchronisation between
 287          * the requesting CPU and the dying CPU actually losing power.
 288          */
 289         if (!platform_cpu_kill(cpu))
 290                 pr_err("CPU%u: unable to kill\n", cpu);
 291 }
 292
 293 /*
 294  * Called from the idle thread for the CPU which has been shutdown.
 295  *
 296  * Note that we disable IRQs here, but do not re-enable them
 297  * before returning to the caller. This is also the behaviour
 298  * of the other hotplug-cpu capable cores, so presumably coming
 299  * out of idle fixes this.
 300  */
 301 void arch_cpu_idle_dead(void)
 302 {
 303         unsigned int cpu = smp_processor_id();
 304
 305         idle_task_exit();
 306
 307         local_irq_disable();
 308
 309         /*
 310          * Flush the data out of the L1 cache for this CPU.  This must be
 311          * before the completion to ensure that data is safely written out
 312          * before platform_cpu_kill() gets called - which may disable
 313          * *this* CPU and power down its cache.
 314          */
 315         flush_cache_louis();
 316
 317         /*
 318          * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
 319          * this returns, power and/or clocks can be removed at any point
 320          * from this CPU and its cache by platform_cpu_kill().
 321          */
 322         complete(&cpu_died);
 323
 324         /*
 325          * Ensure that the cache lines associated with that completion are
 326          * written out.  This covers the case where _this_ CPU is doing the
 327          * powering down, to ensure that the completion is visible to the
 328          * CPU waiting for this one.
 329          */
 330         flush_cache_louis();
 331
 332         /*
 333          * The actual CPU shutdown procedure is at least platform (if not
 334          * CPU) specific.  This may remove power, or it may simply spin.
 335          *
 336          * Platforms are generally expected *NOT* to return from this call,
 337          * although there are some which do because they have no way to
 338          * power down the CPU.  These platforms are the _only_ reason we
 339          * have a return path which uses the fragment of assembly below.
 340          *
 341          * The return path should not be used for platforms which can
 342          * power off the CPU.
 343          */
 344         if (smp_ops.cpu_die)
 345                 smp_ops.cpu_die(cpu);
 346
 347         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 348                 cpu);
 349
 350         /*
 351          * Do not return to the idle loop - jump back to the secondary
 352          * cpu initialisation.  There's some initialisation which needs
 353          * to be repeated to undo the effects of taking the CPU offline.
 354          */
 355         __asm__("mov    sp, %0\n"
 356         "       mov     fp, #0\n"
 357         "       b       secondary_start_kernel"
 358                 :
 359                 : "r" (task_stack_page(current) + THREAD_SIZE - 8));
 360 }
 361 #endif /* CONFIG_HOTPLUG_CPU */
 362
 363 /*
 364  * Called by both boot and secondaries to move global data into
 365  * per-processor storage.
 366  */
 367 static void smp_store_cpu_info(unsigned int cpuid)
 368 {
 369         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 370
 371         cpu_info->loops_per_jiffy = loops_per_jiffy;
 372         cpu_info->cpuid = read_cpuid_id();
 373
 374         store_cpu_topology(cpuid);
 375         check_cpu_icache_size(cpuid);
 376 }
 377
 378 /*
 379  * This is the secondary CPU boot entry.  We're using this CPUs
 380  * idle thread stack, but a set of temporary page tables.
 381  */
 382 asmlinkage void secondary_start_kernel(void)
 383 {
 384         struct mm_struct *mm = &init_mm;
 385         unsigned int cpu;
 386
 387         secondary_biglittle_init();
 388
 389         /*
 390          * The identity mapping is uncached (strongly ordered), so
 391          * switch away from it before attempting any exclusive accesses.
 392          */
 393         cpu_switch_mm(mm->pgd, mm);
 394         local_flush_bp_all();
 395         enter_lazy_tlb(mm, current);
 396         local_flush_tlb_all();
 397
 398         /*
 399          * All kernel threads share the same mm context; grab a
 400          * reference and switch to it.
 401          */
 402         cpu = smp_processor_id();
 403         mmgrab(mm);
 404         current->active_mm = mm;
 405         cpumask_set_cpu(cpu, mm_cpumask(mm));
 406
 407         cpu_init();
 408
 409 #ifndef CONFIG_MMU
 410         setup_vectors_base();
 411 #endif
 412         pr_debug("CPU%u: Booted secondary processor\n", cpu);
 413
 414         preempt_disable();
 415         trace_hardirqs_off();
 416
 417         /*
 418          * Give the platform a chance to do its own initialisation.
 419          */
 420         if (smp_ops.smp_secondary_init)
 421                 smp_ops.smp_secondary_init(cpu);
 422
 423         notify_cpu_starting(cpu);
 424
 425         calibrate_delay();
 426
 427         smp_store_cpu_info(cpu);
 428
 429         /*
 430          * OK, now it's safe to let the boot CPU continue.  Wait for
 431          * the CPU migration code to notice that the CPU is online
 432          * before we continue - which happens after __cpu_up returns.
 433          */
 434         set_cpu_online(cpu, true);
 435
 436         check_other_bugs();
 437
 438         complete(&cpu_running);
 439
 440         local_irq_enable();
 441         local_fiq_enable();
 442         local_abt_enable();
 443
 444         /*
 445          * OK, it's off to the idle thread for us
 446          */
 447         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 448 }
 449
 450 void __init smp_cpus_done(unsigned int max_cpus)
 451 {
 452         int cpu;
 453         unsigned long bogosum = 0;
 454
 455         for_each_online_cpu(cpu)
 456                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 457
 458         printk(KERN_INFO "SMP: Total of %d processors activated "
 459                "(%lu.%02lu BogoMIPS).\n",
 460                num_online_cpus(),
 461                bogosum / (500000/HZ),
 462                (bogosum / (5000/HZ)) % 100);
 463
 464         hyp_mode_check();
 465 }
 466
 467 void __init smp_prepare_boot_cpu(void)
 468 {
 469         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 470 }
 471
 472 void __init smp_prepare_cpus(unsigned int max_cpus)
 473 {
 474         unsigned int ncores = num_possible_cpus();
 475
 476         init_cpu_topology();
 477
 478         smp_store_cpu_info(smp_processor_id());
 479
 480         /*
 481          * are we trying to boot more cores than exist?
 482          */
 483         if (max_cpus > ncores)
 484                 max_cpus = ncores;
 485         if (ncores > 1 && max_cpus) {
 486                 /*
 487                  * Initialise the present map, which describes the set of CPUs
 488                  * actually populated at the present time. A platform should
 489                  * re-initialize the map in the platforms smp_prepare_cpus()
 490                  * if present != possible (e.g. physical hotplug).
 491                  */
 492                 init_cpu_present(cpu_possible_mask);
 493
 494                 /*
 495                  * Initialise the SCU if there are more than one CPU
 496                  * and let them know where to start.
 497                  */
 498                 if (smp_ops.smp_prepare_cpus)
 499                         smp_ops.smp_prepare_cpus(max_cpus);
 500         }
 501 }
 502
 503 static void (*__smp_cross_call)(const struct cpumask *, unsigned int);
 504
 505 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
 506 {
 507         if (!__smp_cross_call)
 508                 __smp_cross_call = fn;
 509 }
 510
 511 static const char *ipi_types[NR_IPI] __tracepoint_string = {
 512 #define S(x,s)  [x] = s
 513         S(IPI_WAKEUP, "CPU wakeup interrupts"),
 514         S(IPI_TIMER, "Timer broadcast interrupts"),
 515         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
 516         S(IPI_CALL_FUNC, "Function call interrupts"),
 517         S(IPI_CPU_STOP, "CPU stop interrupts"),
 518         S(IPI_IRQ_WORK, "IRQ work interrupts"),
 519         S(IPI_COMPLETION, "completion interrupts"),
 520 };
 521
 522 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 523 {
 524         trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
 525         __smp_cross_call(target, ipinr);
 526 }
 527
 528 void show_ipi_list(struct seq_file *p, int prec)
 529 {
 530         unsigned int cpu, i;
 531
 532         for (i = 0; i < NR_IPI; i++) {
 533                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 534
 535                 for_each_online_cpu(cpu)
 536                         seq_printf(p, "%10u ",
 537                                    __get_irq_stat(cpu, ipi_irqs[i]));
 538
 539                 seq_printf(p, " %s\n", ipi_types[i]);
 540         }
 541 }
 542
 543 u64 smp_irq_stat_cpu(unsigned int cpu)
 544 {
 545         u64 sum = 0;
 546         int i;
 547
 548         for (i = 0; i < NR_IPI; i++)
 549                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
 550
 551         return sum;
 552 }
 553
 554 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 555 {
 556         smp_cross_call(mask, IPI_CALL_FUNC);
 557 }
 558
 559 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 560 {
 561         smp_cross_call(mask, IPI_WAKEUP);
 562 }
 563
 564 void arch_send_call_function_single_ipi(int cpu)
 565 {
 566         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
 567 }
 568
 569 #ifdef CONFIG_IRQ_WORK
 570 void arch_irq_work_raise(void)
 571 {
 572         if (arch_irq_work_has_interrupt())
 573                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 574 }
 575 #endif
 576
 577 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 578 void tick_broadcast(const struct cpumask *mask)
 579 {
 580         smp_cross_call(mask, IPI_TIMER);
 581 }
 582 #endif
 583
 584 static DEFINE_RAW_SPINLOCK(stop_lock);
 585
 586 /*
 587  * ipi_cpu_stop - handle IPI from smp_send_stop()
 588  */
 589 static void ipi_cpu_stop(unsigned int cpu)
 590 {
 591         if (system_state <= SYSTEM_RUNNING) {
 592                 raw_spin_lock(&stop_lock);
 593                 pr_crit("CPU%u: stopping\n", cpu);
 594                 dump_stack();
 595                 raw_spin_unlock(&stop_lock);
 596         }
 597
 598         set_cpu_online(cpu, false);
 599
 600         local_fiq_disable();
 601         local_irq_disable();
 602
 603         while (1) {
 604                 cpu_relax();
 605                 wfe();
 606         }
 607 }
 608
 609 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 610
 611 int register_ipi_completion(struct completion *completion, int cpu)
 612 {
 613         per_cpu(cpu_completion, cpu) = completion;
 614         return IPI_COMPLETION;
 615 }
 616
 617 static void ipi_complete(unsigned int cpu)
 618 {
 619         complete(per_cpu(cpu_completion, cpu));
 620 }
 621
 622 /*
 623  * Main handler for inter-processor interrupts
 624  */
 625 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 626 {
 627         handle_IPI(ipinr, regs);
 628 }
 629
 630 void handle_IPI(int ipinr, struct pt_regs *regs)
 631 {
 632         unsigned int cpu = smp_processor_id();
 633         struct pt_regs *old_regs = set_irq_regs(regs);
 634
 635         if ((unsigned)ipinr < NR_IPI) {
 636                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 637                 __inc_irq_stat(cpu, ipi_irqs[ipinr]);
 638         }
 639
 640         switch (ipinr) {
 641         case IPI_WAKEUP:
 642                 break;
 643
 644 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 645         case IPI_TIMER:
 646                 irq_enter();
 647                 tick_receive_broadcast();
 648                 irq_exit();
 649                 break;
 650 #endif
 651
 652         case IPI_RESCHEDULE:
 653                 scheduler_ipi();
 654                 break;
 655
 656         case IPI_CALL_FUNC:
 657                 irq_enter();
 658                 generic_smp_call_function_interrupt();
 659                 irq_exit();
 660                 break;
 661
 662         case IPI_CPU_STOP:
 663                 irq_enter();
 664                 ipi_cpu_stop(cpu);
 665                 irq_exit();
 666                 break;
 667
 668 #ifdef CONFIG_IRQ_WORK
 669         case IPI_IRQ_WORK:
 670                 irq_enter();
 671                 irq_work_run();
 672                 irq_exit();
 673                 break;
 674 #endif
 675
 676         case IPI_COMPLETION:
 677                 irq_enter();
 678                 ipi_complete(cpu);
 679                 irq_exit();
 680                 break;
 681
 682         case IPI_CPU_BACKTRACE:
 683                 printk_nmi_enter();
 684                 irq_enter();
 685                 nmi_cpu_backtrace(regs);
 686                 irq_exit();
 687                 printk_nmi_exit();
 688                 break;
 689
 690         default:
 691                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 692                         cpu, ipinr);
 693                 break;
 694         }
 695
 696         if ((unsigned)ipinr < NR_IPI)
 697                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 698         set_irq_regs(old_regs);
 699 }
 700
 701 void smp_send_reschedule(int cpu)
 702 {
 703         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 704 }
 705
 706 void smp_send_stop(void)
 707 {
 708         unsigned long timeout;
 709         struct cpumask mask;
 710
 711         cpumask_copy(&mask, cpu_online_mask);
 712         cpumask_clear_cpu(smp_processor_id(), &mask);
 713         if (!cpumask_empty(&mask))
 714                 smp_cross_call(&mask, IPI_CPU_STOP);
 715
 716         /* Wait up to one second for other CPUs to stop */
 717         timeout = USEC_PER_SEC;
 718         while (num_online_cpus() > 1 && timeout--)
 719                 udelay(1);
 720
 721         if (num_online_cpus() > 1)
 722                 pr_warn("SMP: failed to stop secondary CPUs\n");
 723 }
 724
 725 /* In case panic() and panic() called at the same time on CPU1 and CPU2,
 726  * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
 727  * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
 728  * kdump fails. So split out the panic_smp_self_stop() and add
 729  * set_cpu_online(smp_processor_id(), false).
 730  */
 731 void panic_smp_self_stop(void)
 732 {
 733         pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
 734                  smp_processor_id());
 735         set_cpu_online(smp_processor_id(), false);
 736         while (1)
 737                 cpu_relax();
 738 }
 739
 740 /*
 741  * not supported here
 742  */
 743 int setup_profiling_timer(unsigned int multiplier)
 744 {
 745         return -EINVAL;
 746 }
 747
 748 #ifdef CONFIG_CPU_FREQ
 749
 750 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 751 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 752 static unsigned long global_l_p_j_ref;
 753 static unsigned long global_l_p_j_ref_freq;
 754
 755 static int cpufreq_callback(struct notifier_block *nb,
 756                                         unsigned long val, void *data)
 757 {
 758         struct cpufreq_freqs *freq = data;
 759         struct cpumask *cpus = freq->policy->cpus;
 760         int cpu, first = cpumask_first(cpus);
 761         unsigned int lpj;
 762
 763         if (freq->flags & CPUFREQ_CONST_LOOPS)
 764                 return NOTIFY_OK;
 765
 766         if (!per_cpu(l_p_j_ref, first)) {
 767                 for_each_cpu(cpu, cpus) {
 768                         per_cpu(l_p_j_ref, cpu) =
 769                                 per_cpu(cpu_data, cpu).loops_per_jiffy;
 770                         per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 771                 }
 772
 773                 if (!global_l_p_j_ref) {
 774                         global_l_p_j_ref = loops_per_jiffy;
 775                         global_l_p_j_ref_freq = freq->old;
 776                 }
 777         }
 778
 779         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 780             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 781                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 782                                                 global_l_p_j_ref_freq,
 783                                                 freq->new);
 784
 785                 lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
 786                                     per_cpu(l_p_j_ref_freq, first), freq->new);
 787                 for_each_cpu(cpu, cpus)
 788                         per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
 789         }
 790         return NOTIFY_OK;
 791 }
 792
 793 static struct notifier_block cpufreq_notifier = {
 794         .notifier_call  = cpufreq_callback,
 795 };
 796
 797 static int __init register_cpufreq_notifier(void)
 798 {
 799         return cpufreq_register_notifier(&cpufreq_notifier,
 800                                                 CPUFREQ_TRANSITION_NOTIFIER);
 801 }
 802 core_initcall(register_cpufreq_notifier);
 803
 804 #endif
 805
 806 static void raise_nmi(cpumask_t *mask)
 807 {
 808         __smp_cross_call(mask, IPI_CPU_BACKTRACE);
 809 }
 810
 811 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 812 {
 813         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
 814 }