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 }
 376
 377 /*
 378  * This is the secondary CPU boot entry.  We're using this CPUs
 379  * idle thread stack, but a set of temporary page tables.
 380  */
 381 asmlinkage void secondary_start_kernel(void)
 382 {
 383         struct mm_struct *mm = &init_mm;
 384         unsigned int cpu;
 385
 386         secondary_biglittle_init();
 387
 388         /*
 389          * The identity mapping is uncached (strongly ordered), so
 390          * switch away from it before attempting any exclusive accesses.
 391          */
 392         cpu_switch_mm(mm->pgd, mm);
 393         local_flush_bp_all();
 394         enter_lazy_tlb(mm, current);
 395         local_flush_tlb_all();
 396
 397         /*
 398          * All kernel threads share the same mm context; grab a
 399          * reference and switch to it.
 400          */
 401         cpu = smp_processor_id();
 402         mmgrab(mm);
 403         current->active_mm = mm;
 404         cpumask_set_cpu(cpu, mm_cpumask(mm));
 405
 406         cpu_init();
 407
 408 #ifndef CONFIG_MMU
 409         setup_vectors_base();
 410 #endif
 411         pr_debug("CPU%u: Booted secondary processor\n", cpu);
 412
 413         preempt_disable();
 414         trace_hardirqs_off();
 415
 416         /*
 417          * Give the platform a chance to do its own initialisation.
 418          */
 419         if (smp_ops.smp_secondary_init)
 420                 smp_ops.smp_secondary_init(cpu);
 421
 422         notify_cpu_starting(cpu);
 423
 424         calibrate_delay();
 425
 426         smp_store_cpu_info(cpu);
 427
 428         /*
 429          * OK, now it's safe to let the boot CPU continue.  Wait for
 430          * the CPU migration code to notice that the CPU is online
 431          * before we continue - which happens after __cpu_up returns.
 432          */
 433         set_cpu_online(cpu, true);
 434
 435         check_other_bugs();
 436
 437         complete(&cpu_running);
 438
 439         local_irq_enable();
 440         local_fiq_enable();
 441         local_abt_enable();
 442
 443         /*
 444          * OK, it's off to the idle thread for us
 445          */
 446         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 447 }
 448
 449 void __init smp_cpus_done(unsigned int max_cpus)
 450 {
 451         int cpu;
 452         unsigned long bogosum = 0;
 453
 454         for_each_online_cpu(cpu)
 455                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 456
 457         printk(KERN_INFO "SMP: Total of %d processors activated "
 458                "(%lu.%02lu BogoMIPS).\n",
 459                num_online_cpus(),
 460                bogosum / (500000/HZ),
 461                (bogosum / (5000/HZ)) % 100);
 462
 463         hyp_mode_check();
 464 }
 465
 466 void __init smp_prepare_boot_cpu(void)
 467 {
 468         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 469 }
 470
 471 void __init smp_prepare_cpus(unsigned int max_cpus)
 472 {
 473         unsigned int ncores = num_possible_cpus();
 474
 475         init_cpu_topology();
 476
 477         smp_store_cpu_info(smp_processor_id());
 478
 479         /*
 480          * are we trying to boot more cores than exist?
 481          */
 482         if (max_cpus > ncores)
 483                 max_cpus = ncores;
 484         if (ncores > 1 && max_cpus) {
 485                 /*
 486                  * Initialise the present map, which describes the set of CPUs
 487                  * actually populated at the present time. A platform should
 488                  * re-initialize the map in the platforms smp_prepare_cpus()
 489                  * if present != possible (e.g. physical hotplug).
 490                  */
 491                 init_cpu_present(cpu_possible_mask);
 492
 493                 /*
 494                  * Initialise the SCU if there are more than one CPU
 495                  * and let them know where to start.
 496                  */
 497                 if (smp_ops.smp_prepare_cpus)
 498                         smp_ops.smp_prepare_cpus(max_cpus);
 499         }
 500 }
 501
 502 static void (*__smp_cross_call)(const struct cpumask *, unsigned int);
 503
 504 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
 505 {
 506         if (!__smp_cross_call)
 507                 __smp_cross_call = fn;
 508 }
 509
 510 static const char *ipi_types[NR_IPI] __tracepoint_string = {
 511 #define S(x,s)  [x] = s
 512         S(IPI_WAKEUP, "CPU wakeup interrupts"),
 513         S(IPI_TIMER, "Timer broadcast interrupts"),
 514         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
 515         S(IPI_CALL_FUNC, "Function call interrupts"),
 516         S(IPI_CPU_STOP, "CPU stop interrupts"),
 517         S(IPI_IRQ_WORK, "IRQ work interrupts"),
 518         S(IPI_COMPLETION, "completion interrupts"),
 519 };
 520
 521 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 522 {
 523         trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
 524         __smp_cross_call(target, ipinr);
 525 }
 526
 527 void show_ipi_list(struct seq_file *p, int prec)
 528 {
 529         unsigned int cpu, i;
 530
 531         for (i = 0; i < NR_IPI; i++) {
 532                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 533
 534                 for_each_online_cpu(cpu)
 535                         seq_printf(p, "%10u ",
 536                                    __get_irq_stat(cpu, ipi_irqs[i]));
 537
 538                 seq_printf(p, " %s\n", ipi_types[i]);
 539         }
 540 }
 541
 542 u64 smp_irq_stat_cpu(unsigned int cpu)
 543 {
 544         u64 sum = 0;
 545         int i;
 546
 547         for (i = 0; i < NR_IPI; i++)
 548                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
 549
 550         return sum;
 551 }
 552
 553 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 554 {
 555         smp_cross_call(mask, IPI_CALL_FUNC);
 556 }
 557
 558 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 559 {
 560         smp_cross_call(mask, IPI_WAKEUP);
 561 }
 562
 563 void arch_send_call_function_single_ipi(int cpu)
 564 {
 565         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
 566 }
 567
 568 #ifdef CONFIG_IRQ_WORK
 569 void arch_irq_work_raise(void)
 570 {
 571         if (arch_irq_work_has_interrupt())
 572                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 573 }
 574 #endif
 575
 576 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 577 void tick_broadcast(const struct cpumask *mask)
 578 {
 579         smp_cross_call(mask, IPI_TIMER);
 580 }
 581 #endif
 582
 583 static DEFINE_RAW_SPINLOCK(stop_lock);
 584
 585 /*
 586  * ipi_cpu_stop - handle IPI from smp_send_stop()
 587  */
 588 static void ipi_cpu_stop(unsigned int cpu)
 589 {
 590         if (system_state <= SYSTEM_RUNNING) {
 591                 raw_spin_lock(&stop_lock);
 592                 pr_crit("CPU%u: stopping\n", cpu);
 593                 dump_stack();
 594                 raw_spin_unlock(&stop_lock);
 595         }
 596
 597         set_cpu_online(cpu, false);
 598
 599         local_fiq_disable();
 600         local_irq_disable();
 601
 602         while (1) {
 603                 cpu_relax();
 604                 wfe();
 605         }
 606 }
 607
 608 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 609
 610 int register_ipi_completion(struct completion *completion, int cpu)
 611 {
 612         per_cpu(cpu_completion, cpu) = completion;
 613         return IPI_COMPLETION;
 614 }
 615
 616 static void ipi_complete(unsigned int cpu)
 617 {
 618         complete(per_cpu(cpu_completion, cpu));
 619 }
 620
 621 /*
 622  * Main handler for inter-processor interrupts
 623  */
 624 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 625 {
 626         handle_IPI(ipinr, regs);
 627 }
 628
 629 void handle_IPI(int ipinr, struct pt_regs *regs)
 630 {
 631         unsigned int cpu = smp_processor_id();
 632         struct pt_regs *old_regs = set_irq_regs(regs);
 633
 634         if ((unsigned)ipinr < NR_IPI) {
 635                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 636                 __inc_irq_stat(cpu, ipi_irqs[ipinr]);
 637         }
 638
 639         switch (ipinr) {
 640         case IPI_WAKEUP:
 641                 break;
 642
 643 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 644         case IPI_TIMER:
 645                 irq_enter();
 646                 tick_receive_broadcast();
 647                 irq_exit();
 648                 break;
 649 #endif
 650
 651         case IPI_RESCHEDULE:
 652                 scheduler_ipi();
 653                 break;
 654
 655         case IPI_CALL_FUNC:
 656                 irq_enter();
 657                 generic_smp_call_function_interrupt();
 658                 irq_exit();
 659                 break;
 660
 661         case IPI_CPU_STOP:
 662                 irq_enter();
 663                 ipi_cpu_stop(cpu);
 664                 irq_exit();
 665                 break;
 666
 667 #ifdef CONFIG_IRQ_WORK
 668         case IPI_IRQ_WORK:
 669                 irq_enter();
 670                 irq_work_run();
 671                 irq_exit();
 672                 break;
 673 #endif
 674
 675         case IPI_COMPLETION:
 676                 irq_enter();
 677                 ipi_complete(cpu);
 678                 irq_exit();
 679                 break;
 680
 681         case IPI_CPU_BACKTRACE:
 682                 printk_nmi_enter();
 683                 irq_enter();
 684                 nmi_cpu_backtrace(regs);
 685                 irq_exit();
 686                 printk_nmi_exit();
 687                 break;
 688
 689         default:
 690                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 691                         cpu, ipinr);
 692                 break;
 693         }
 694
 695         if ((unsigned)ipinr < NR_IPI)
 696                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 697         set_irq_regs(old_regs);
 698 }
 699
 700 void smp_send_reschedule(int cpu)
 701 {
 702         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 703 }
 704
 705 void smp_send_stop(void)
 706 {
 707         unsigned long timeout;
 708         struct cpumask mask;
 709
 710         cpumask_copy(&mask, cpu_online_mask);
 711         cpumask_clear_cpu(smp_processor_id(), &mask);
 712         if (!cpumask_empty(&mask))
 713                 smp_cross_call(&mask, IPI_CPU_STOP);
 714
 715         /* Wait up to one second for other CPUs to stop */
 716         timeout = USEC_PER_SEC;
 717         while (num_online_cpus() > 1 && timeout--)
 718                 udelay(1);
 719
 720         if (num_online_cpus() > 1)
 721                 pr_warn("SMP: failed to stop secondary CPUs\n");
 722 }
 723
 724 /* In case panic() and panic() called at the same time on CPU1 and CPU2,
 725  * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
 726  * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
 727  * kdump fails. So split out the panic_smp_self_stop() and add
 728  * set_cpu_online(smp_processor_id(), false).
 729  */
 730 void panic_smp_self_stop(void)
 731 {
 732         pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
 733                  smp_processor_id());
 734         set_cpu_online(smp_processor_id(), false);
 735         while (1)
 736                 cpu_relax();
 737 }
 738
 739 /*
 740  * not supported here
 741  */
 742 int setup_profiling_timer(unsigned int multiplier)
 743 {
 744         return -EINVAL;
 745 }
 746
 747 #ifdef CONFIG_CPU_FREQ
 748
 749 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 750 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 751 static unsigned long global_l_p_j_ref;
 752 static unsigned long global_l_p_j_ref_freq;
 753
 754 static int cpufreq_callback(struct notifier_block *nb,
 755                                         unsigned long val, void *data)
 756 {
 757         struct cpufreq_freqs *freq = data;
 758         struct cpumask *cpus = freq->policy->cpus;
 759         int cpu, first = cpumask_first(cpus);
 760         unsigned int lpj;
 761
 762         if (freq->flags & CPUFREQ_CONST_LOOPS)
 763                 return NOTIFY_OK;
 764
 765         if (!per_cpu(l_p_j_ref, first)) {
 766                 for_each_cpu(cpu, cpus) {
 767                         per_cpu(l_p_j_ref, cpu) =
 768                                 per_cpu(cpu_data, cpu).loops_per_jiffy;
 769                         per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 770                 }
 771
 772                 if (!global_l_p_j_ref) {
 773                         global_l_p_j_ref = loops_per_jiffy;
 774                         global_l_p_j_ref_freq = freq->old;
 775                 }
 776         }
 777
 778         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 779             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 780                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 781                                                 global_l_p_j_ref_freq,
 782                                                 freq->new);
 783
 784                 lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
 785                                     per_cpu(l_p_j_ref_freq, first), freq->new);
 786                 for_each_cpu(cpu, cpus)
 787                         per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
 788         }
 789         return NOTIFY_OK;
 790 }
 791
 792 static struct notifier_block cpufreq_notifier = {
 793         .notifier_call  = cpufreq_callback,
 794 };
 795
 796 static int __init register_cpufreq_notifier(void)
 797 {
 798         return cpufreq_register_notifier(&cpufreq_notifier,
 799                                                 CPUFREQ_TRANSITION_NOTIFIER);
 800 }
 801 core_initcall(register_cpufreq_notifier);
 802
 803 #endif
 804
 805 static void raise_nmi(cpumask_t *mask)
 806 {
 807         __smp_cross_call(mask, IPI_CPU_BACKTRACE);
 808 }
 809
 810 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 811 {
 812         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
 813 }