linux/arch/arm/kernel/smp.c
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   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#include <linux/kernel_stat.h>
  30
  31#include <linux/atomic.h>
  32#include <asm/bugs.h>
  33#include <asm/smp.h>
  34#include <asm/cacheflush.h>
  35#include <asm/cpu.h>
  36#include <asm/cputype.h>
  37#include <asm/exception.h>
  38#include <asm/idmap.h>
  39#include <asm/topology.h>
  40#include <asm/mmu_context.h>
  41#include <asm/procinfo.h>
  42#include <asm/processor.h>
  43#include <asm/sections.h>
  44#include <asm/tlbflush.h>
  45#include <asm/ptrace.h>
  46#include <asm/smp_plat.h>
  47#include <asm/virt.h>
  48#include <asm/mach/arch.h>
  49#include <asm/mpu.h>
  50
  51#define CREATE_TRACE_POINTS
  52#include <trace/events/ipi.h>
  53
  54/*
  55 * as from 2.5, kernels no longer have an init_tasks structure
  56 * so we need some other way of telling a new secondary core
  57 * where to place its SVC stack
  58 */
  59struct secondary_data secondary_data;
  60
  61enum ipi_msg_type {
  62        IPI_WAKEUP,
  63        IPI_TIMER,
  64        IPI_RESCHEDULE,
  65        IPI_CALL_FUNC,
  66        IPI_CPU_STOP,
  67        IPI_IRQ_WORK,
  68        IPI_COMPLETION,
  69        NR_IPI,
  70        /*
  71         * CPU_BACKTRACE is special and not included in NR_IPI
  72         * or tracable with trace_ipi_*
  73         */
  74        IPI_CPU_BACKTRACE = NR_IPI,
  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        MAX_IPI
  81};
  82
  83static int ipi_irq_base __read_mostly;
  84static int nr_ipi __read_mostly = NR_IPI;
  85static struct irq_desc *ipi_desc[MAX_IPI] __read_mostly;
  86
  87static void ipi_setup(int cpu);
  88
  89static DECLARE_COMPLETION(cpu_running);
  90
  91static struct smp_operations smp_ops __ro_after_init;
  92
  93void __init smp_set_ops(const struct smp_operations *ops)
  94{
  95        if (ops)
  96                smp_ops = *ops;
  97};
  98
  99static unsigned long get_arch_pgd(pgd_t *pgd)
 100{
 101#ifdef CONFIG_ARM_LPAE
 102        return __phys_to_pfn(virt_to_phys(pgd));
 103#else
 104        return virt_to_phys(pgd);
 105#endif
 106}
 107
 108#if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
 109static int secondary_biglittle_prepare(unsigned int cpu)
 110{
 111        if (!cpu_vtable[cpu])
 112                cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL);
 113
 114        return cpu_vtable[cpu] ? 0 : -ENOMEM;
 115}
 116
 117static void secondary_biglittle_init(void)
 118{
 119        init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
 120}
 121#else
 122static int secondary_biglittle_prepare(unsigned int cpu)
 123{
 124        return 0;
 125}
 126
 127static void secondary_biglittle_init(void)
 128{
 129}
 130#endif
 131
 132int __cpu_up(unsigned int cpu, struct task_struct *idle)
 133{
 134        int ret;
 135
 136        if (!smp_ops.smp_boot_secondary)
 137                return -ENOSYS;
 138
 139        ret = secondary_biglittle_prepare(cpu);
 140        if (ret)
 141                return ret;
 142
 143        /*
 144         * We need to tell the secondary core where to find
 145         * its stack and the page tables.
 146         */
 147        secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
 148#ifdef CONFIG_ARM_MPU
 149        secondary_data.mpu_rgn_info = &mpu_rgn_info;
 150#endif
 151
 152#ifdef CONFIG_MMU
 153        secondary_data.pgdir = virt_to_phys(idmap_pgd);
 154        secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
 155#endif
 156        sync_cache_w(&secondary_data);
 157
 158        /*
 159         * Now bring the CPU into our world.
 160         */
 161        ret = smp_ops.smp_boot_secondary(cpu, idle);
 162        if (ret == 0) {
 163                /*
 164                 * CPU was successfully started, wait for it
 165                 * to come online or time out.
 166                 */
 167                wait_for_completion_timeout(&cpu_running,
 168                                                 msecs_to_jiffies(1000));
 169
 170                if (!cpu_online(cpu)) {
 171                        pr_crit("CPU%u: failed to come online\n", cpu);
 172                        ret = -EIO;
 173                }
 174        } else {
 175                pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
 176        }
 177
 178
 179        memset(&secondary_data, 0, sizeof(secondary_data));
 180        return ret;
 181}
 182
 183/* platform specific SMP operations */
 184void __init smp_init_cpus(void)
 185{
 186        if (smp_ops.smp_init_cpus)
 187                smp_ops.smp_init_cpus();
 188}
 189
 190int platform_can_secondary_boot(void)
 191{
 192        return !!smp_ops.smp_boot_secondary;
 193}
 194
 195int platform_can_cpu_hotplug(void)
 196{
 197#ifdef CONFIG_HOTPLUG_CPU
 198        if (smp_ops.cpu_kill)
 199                return 1;
 200#endif
 201
 202        return 0;
 203}
 204
 205#ifdef CONFIG_HOTPLUG_CPU
 206static int platform_cpu_kill(unsigned int cpu)
 207{
 208        if (smp_ops.cpu_kill)
 209                return smp_ops.cpu_kill(cpu);
 210        return 1;
 211}
 212
 213static int platform_cpu_disable(unsigned int cpu)
 214{
 215        if (smp_ops.cpu_disable)
 216                return smp_ops.cpu_disable(cpu);
 217
 218        return 0;
 219}
 220
 221int platform_can_hotplug_cpu(unsigned int cpu)
 222{
 223        /* cpu_die must be specified to support hotplug */
 224        if (!smp_ops.cpu_die)
 225                return 0;
 226
 227        if (smp_ops.cpu_can_disable)
 228                return smp_ops.cpu_can_disable(cpu);
 229
 230        /*
 231         * By default, allow disabling all CPUs except the first one,
 232         * since this is special on a lot of platforms, e.g. because
 233         * of clock tick interrupts.
 234         */
 235        return cpu != 0;
 236}
 237
 238static void ipi_teardown(int cpu)
 239{
 240        int i;
 241
 242        if (WARN_ON_ONCE(!ipi_irq_base))
 243                return;
 244
 245        for (i = 0; i < nr_ipi; i++)
 246                disable_percpu_irq(ipi_irq_base + i);
 247}
 248
 249/*
 250 * __cpu_disable runs on the processor to be shutdown.
 251 */
 252int __cpu_disable(void)
 253{
 254        unsigned int cpu = smp_processor_id();
 255        int ret;
 256
 257        ret = platform_cpu_disable(cpu);
 258        if (ret)
 259                return ret;
 260
 261#ifdef CONFIG_GENERIC_ARCH_TOPOLOGY
 262        remove_cpu_topology(cpu);
 263#endif
 264
 265        /*
 266         * Take this CPU offline.  Once we clear this, we can't return,
 267         * and we must not schedule until we're ready to give up the cpu.
 268         */
 269        set_cpu_online(cpu, false);
 270        ipi_teardown(cpu);
 271
 272        /*
 273         * OK - migrate IRQs away from this CPU
 274         */
 275        irq_migrate_all_off_this_cpu();
 276
 277        /*
 278         * Flush user cache and TLB mappings, and then remove this CPU
 279         * from the vm mask set of all processes.
 280         *
 281         * Caches are flushed to the Level of Unification Inner Shareable
 282         * to write-back dirty lines to unified caches shared by all CPUs.
 283         */
 284        flush_cache_louis();
 285        local_flush_tlb_all();
 286
 287        return 0;
 288}
 289
 290/*
 291 * called on the thread which is asking for a CPU to be shutdown -
 292 * waits until shutdown has completed, or it is timed out.
 293 */
 294void __cpu_die(unsigned int cpu)
 295{
 296        if (!cpu_wait_death(cpu, 5)) {
 297                pr_err("CPU%u: cpu didn't die\n", cpu);
 298                return;
 299        }
 300        pr_debug("CPU%u: shutdown\n", cpu);
 301
 302        clear_tasks_mm_cpumask(cpu);
 303        /*
 304         * platform_cpu_kill() is generally expected to do the powering off
 305         * and/or cutting of clocks to the dying CPU.  Optionally, this may
 306         * be done by the CPU which is dying in preference to supporting
 307         * this call, but that means there is _no_ synchronisation between
 308         * the requesting CPU and the dying CPU actually losing power.
 309         */
 310        if (!platform_cpu_kill(cpu))
 311                pr_err("CPU%u: unable to kill\n", cpu);
 312}
 313
 314/*
 315 * Called from the idle thread for the CPU which has been shutdown.
 316 *
 317 * Note that we disable IRQs here, but do not re-enable them
 318 * before returning to the caller. This is also the behaviour
 319 * of the other hotplug-cpu capable cores, so presumably coming
 320 * out of idle fixes this.
 321 */
 322void arch_cpu_idle_dead(void)
 323{
 324        unsigned int cpu = smp_processor_id();
 325
 326        idle_task_exit();
 327
 328        local_irq_disable();
 329
 330        /*
 331         * Flush the data out of the L1 cache for this CPU.  This must be
 332         * before the completion to ensure that data is safely written out
 333         * before platform_cpu_kill() gets called - which may disable
 334         * *this* CPU and power down its cache.
 335         */
 336        flush_cache_louis();
 337
 338        /*
 339         * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
 340         * this returns, power and/or clocks can be removed at any point
 341         * from this CPU and its cache by platform_cpu_kill().
 342         */
 343        (void)cpu_report_death();
 344
 345        /*
 346         * Ensure that the cache lines associated with that completion are
 347         * written out.  This covers the case where _this_ CPU is doing the
 348         * powering down, to ensure that the completion is visible to the
 349         * CPU waiting for this one.
 350         */
 351        flush_cache_louis();
 352
 353        /*
 354         * The actual CPU shutdown procedure is at least platform (if not
 355         * CPU) specific.  This may remove power, or it may simply spin.
 356         *
 357         * Platforms are generally expected *NOT* to return from this call,
 358         * although there are some which do because they have no way to
 359         * power down the CPU.  These platforms are the _only_ reason we
 360         * have a return path which uses the fragment of assembly below.
 361         *
 362         * The return path should not be used for platforms which can
 363         * power off the CPU.
 364         */
 365        if (smp_ops.cpu_die)
 366                smp_ops.cpu_die(cpu);
 367
 368        pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 369                cpu);
 370
 371        /*
 372         * Do not return to the idle loop - jump back to the secondary
 373         * cpu initialisation.  There's some initialisation which needs
 374         * to be repeated to undo the effects of taking the CPU offline.
 375         */
 376        __asm__("mov    sp, %0\n"
 377        "       mov     fp, #0\n"
 378        "       b       secondary_start_kernel"
 379                :
 380                : "r" (task_stack_page(current) + THREAD_SIZE - 8));
 381}
 382#endif /* CONFIG_HOTPLUG_CPU */
 383
 384/*
 385 * Called by both boot and secondaries to move global data into
 386 * per-processor storage.
 387 */
 388static void smp_store_cpu_info(unsigned int cpuid)
 389{
 390        struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 391
 392        cpu_info->loops_per_jiffy = loops_per_jiffy;
 393        cpu_info->cpuid = read_cpuid_id();
 394
 395        store_cpu_topology(cpuid);
 396        check_cpu_icache_size(cpuid);
 397}
 398
 399/*
 400 * This is the secondary CPU boot entry.  We're using this CPUs
 401 * idle thread stack, but a set of temporary page tables.
 402 */
 403asmlinkage void secondary_start_kernel(void)
 404{
 405        struct mm_struct *mm = &init_mm;
 406        unsigned int cpu;
 407
 408        secondary_biglittle_init();
 409
 410        /*
 411         * The identity mapping is uncached (strongly ordered), so
 412         * switch away from it before attempting any exclusive accesses.
 413         */
 414        cpu_switch_mm(mm->pgd, mm);
 415        local_flush_bp_all();
 416        enter_lazy_tlb(mm, current);
 417        local_flush_tlb_all();
 418
 419        /*
 420         * All kernel threads share the same mm context; grab a
 421         * reference and switch to it.
 422         */
 423        cpu = smp_processor_id();
 424        mmgrab(mm);
 425        current->active_mm = mm;
 426        cpumask_set_cpu(cpu, mm_cpumask(mm));
 427
 428        cpu_init();
 429
 430#ifndef CONFIG_MMU
 431        setup_vectors_base();
 432#endif
 433        pr_debug("CPU%u: Booted secondary processor\n", cpu);
 434
 435        trace_hardirqs_off();
 436
 437        /*
 438         * Give the platform a chance to do its own initialisation.
 439         */
 440        if (smp_ops.smp_secondary_init)
 441                smp_ops.smp_secondary_init(cpu);
 442
 443        notify_cpu_starting(cpu);
 444
 445        ipi_setup(cpu);
 446
 447        calibrate_delay();
 448
 449        smp_store_cpu_info(cpu);
 450
 451        /*
 452         * OK, now it's safe to let the boot CPU continue.  Wait for
 453         * the CPU migration code to notice that the CPU is online
 454         * before we continue - which happens after __cpu_up returns.
 455         */
 456        set_cpu_online(cpu, true);
 457
 458        check_other_bugs();
 459
 460        complete(&cpu_running);
 461
 462        local_irq_enable();
 463        local_fiq_enable();
 464        local_abt_enable();
 465
 466        /*
 467         * OK, it's off to the idle thread for us
 468         */
 469        cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 470}
 471
 472void __init smp_cpus_done(unsigned int max_cpus)
 473{
 474        int cpu;
 475        unsigned long bogosum = 0;
 476
 477        for_each_online_cpu(cpu)
 478                bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 479
 480        printk(KERN_INFO "SMP: Total of %d processors activated "
 481               "(%lu.%02lu BogoMIPS).\n",
 482               num_online_cpus(),
 483               bogosum / (500000/HZ),
 484               (bogosum / (5000/HZ)) % 100);
 485
 486        hyp_mode_check();
 487}
 488
 489void __init smp_prepare_boot_cpu(void)
 490{
 491        set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 492}
 493
 494void __init smp_prepare_cpus(unsigned int max_cpus)
 495{
 496        unsigned int ncores = num_possible_cpus();
 497
 498        init_cpu_topology();
 499
 500        smp_store_cpu_info(smp_processor_id());
 501
 502        /*
 503         * are we trying to boot more cores than exist?
 504         */
 505        if (max_cpus > ncores)
 506                max_cpus = ncores;
 507        if (ncores > 1 && max_cpus) {
 508                /*
 509                 * Initialise the present map, which describes the set of CPUs
 510                 * actually populated at the present time. A platform should
 511                 * re-initialize the map in the platforms smp_prepare_cpus()
 512                 * if present != possible (e.g. physical hotplug).
 513                 */
 514                init_cpu_present(cpu_possible_mask);
 515
 516                /*
 517                 * Initialise the SCU if there are more than one CPU
 518                 * and let them know where to start.
 519                 */
 520                if (smp_ops.smp_prepare_cpus)
 521                        smp_ops.smp_prepare_cpus(max_cpus);
 522        }
 523}
 524
 525static const char *ipi_types[NR_IPI] __tracepoint_string = {
 526        [IPI_WAKEUP]            = "CPU wakeup interrupts",
 527        [IPI_TIMER]             = "Timer broadcast interrupts",
 528        [IPI_RESCHEDULE]        = "Rescheduling interrupts",
 529        [IPI_CALL_FUNC]         = "Function call interrupts",
 530        [IPI_CPU_STOP]          = "CPU stop interrupts",
 531        [IPI_IRQ_WORK]          = "IRQ work interrupts",
 532        [IPI_COMPLETION]        = "completion interrupts",
 533};
 534
 535static void smp_cross_call(const struct cpumask *target, unsigned int ipinr);
 536
 537void show_ipi_list(struct seq_file *p, int prec)
 538{
 539        unsigned int cpu, i;
 540
 541        for (i = 0; i < NR_IPI; i++) {
 542                if (!ipi_desc[i])
 543                        continue;
 544
 545                seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 546
 547                for_each_online_cpu(cpu)
 548                        seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
 549
 550                seq_printf(p, " %s\n", ipi_types[i]);
 551        }
 552}
 553
 554void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 555{
 556        smp_cross_call(mask, IPI_CALL_FUNC);
 557}
 558
 559void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 560{
 561        smp_cross_call(mask, IPI_WAKEUP);
 562}
 563
 564void 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
 570void 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
 578void tick_broadcast(const struct cpumask *mask)
 579{
 580        smp_cross_call(mask, IPI_TIMER);
 581}
 582#endif
 583
 584static DEFINE_RAW_SPINLOCK(stop_lock);
 585
 586/*
 587 * ipi_cpu_stop - handle IPI from smp_send_stop()
 588 */
 589static 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
 609static DEFINE_PER_CPU(struct completion *, cpu_completion);
 610
 611int register_ipi_completion(struct completion *completion, int cpu)
 612{
 613        per_cpu(cpu_completion, cpu) = completion;
 614        return IPI_COMPLETION;
 615}
 616
 617static 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 */
 625asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 626{
 627        handle_IPI(ipinr, regs);
 628}
 629
 630static void do_handle_IPI(int ipinr)
 631{
 632        unsigned int cpu = smp_processor_id();
 633
 634        if ((unsigned)ipinr < NR_IPI)
 635                trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 636
 637        switch (ipinr) {
 638        case IPI_WAKEUP:
 639                break;
 640
 641#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 642        case IPI_TIMER:
 643                tick_receive_broadcast();
 644                break;
 645#endif
 646
 647        case IPI_RESCHEDULE:
 648                scheduler_ipi();
 649                break;
 650
 651        case IPI_CALL_FUNC:
 652                generic_smp_call_function_interrupt();
 653                break;
 654
 655        case IPI_CPU_STOP:
 656                ipi_cpu_stop(cpu);
 657                break;
 658
 659#ifdef CONFIG_IRQ_WORK
 660        case IPI_IRQ_WORK:
 661                irq_work_run();
 662                break;
 663#endif
 664
 665        case IPI_COMPLETION:
 666                ipi_complete(cpu);
 667                break;
 668
 669        case IPI_CPU_BACKTRACE:
 670                printk_nmi_enter();
 671                nmi_cpu_backtrace(get_irq_regs());
 672                printk_nmi_exit();
 673                break;
 674
 675        default:
 676                pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 677                        cpu, ipinr);
 678                break;
 679        }
 680
 681        if ((unsigned)ipinr < NR_IPI)
 682                trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 683}
 684
 685/* Legacy version, should go away once all irqchips have been converted */
 686void handle_IPI(int ipinr, struct pt_regs *regs)
 687{
 688        struct pt_regs *old_regs = set_irq_regs(regs);
 689
 690        irq_enter();
 691        do_handle_IPI(ipinr);
 692        irq_exit();
 693
 694        set_irq_regs(old_regs);
 695}
 696
 697static irqreturn_t ipi_handler(int irq, void *data)
 698{
 699        do_handle_IPI(irq - ipi_irq_base);
 700        return IRQ_HANDLED;
 701}
 702
 703static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 704{
 705        trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
 706        __ipi_send_mask(ipi_desc[ipinr], target);
 707}
 708
 709static void ipi_setup(int cpu)
 710{
 711        int i;
 712
 713        if (WARN_ON_ONCE(!ipi_irq_base))
 714                return;
 715
 716        for (i = 0; i < nr_ipi; i++)
 717                enable_percpu_irq(ipi_irq_base + i, 0);
 718}
 719
 720void __init set_smp_ipi_range(int ipi_base, int n)
 721{
 722        int i;
 723
 724        WARN_ON(n < MAX_IPI);
 725        nr_ipi = min(n, MAX_IPI);
 726
 727        for (i = 0; i < nr_ipi; i++) {
 728                int err;
 729
 730                err = request_percpu_irq(ipi_base + i, ipi_handler,
 731                                         "IPI", &irq_stat);
 732                WARN_ON(err);
 733
 734                ipi_desc[i] = irq_to_desc(ipi_base + i);
 735                irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
 736        }
 737
 738        ipi_irq_base = ipi_base;
 739
 740        /* Setup the boot CPU immediately */
 741        ipi_setup(smp_processor_id());
 742}
 743
 744void smp_send_reschedule(int cpu)
 745{
 746        smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 747}
 748
 749void smp_send_stop(void)
 750{
 751        unsigned long timeout;
 752        struct cpumask mask;
 753
 754        cpumask_copy(&mask, cpu_online_mask);
 755        cpumask_clear_cpu(smp_processor_id(), &mask);
 756        if (!cpumask_empty(&mask))
 757                smp_cross_call(&mask, IPI_CPU_STOP);
 758
 759        /* Wait up to one second for other CPUs to stop */
 760        timeout = USEC_PER_SEC;
 761        while (num_online_cpus() > 1 && timeout--)
 762                udelay(1);
 763
 764        if (num_online_cpus() > 1)
 765                pr_warn("SMP: failed to stop secondary CPUs\n");
 766}
 767
 768/* In case panic() and panic() called at the same time on CPU1 and CPU2,
 769 * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
 770 * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
 771 * kdump fails. So split out the panic_smp_self_stop() and add
 772 * set_cpu_online(smp_processor_id(), false).
 773 */
 774void panic_smp_self_stop(void)
 775{
 776        pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
 777                 smp_processor_id());
 778        set_cpu_online(smp_processor_id(), false);
 779        while (1)
 780                cpu_relax();
 781}
 782
 783/*
 784 * not supported here
 785 */
 786int setup_profiling_timer(unsigned int multiplier)
 787{
 788        return -EINVAL;
 789}
 790
 791#ifdef CONFIG_CPU_FREQ
 792
 793static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 794static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 795static unsigned long global_l_p_j_ref;
 796static unsigned long global_l_p_j_ref_freq;
 797
 798static int cpufreq_callback(struct notifier_block *nb,
 799                                        unsigned long val, void *data)
 800{
 801        struct cpufreq_freqs *freq = data;
 802        struct cpumask *cpus = freq->policy->cpus;
 803        int cpu, first = cpumask_first(cpus);
 804        unsigned int lpj;
 805
 806        if (freq->flags & CPUFREQ_CONST_LOOPS)
 807                return NOTIFY_OK;
 808
 809        if (!per_cpu(l_p_j_ref, first)) {
 810                for_each_cpu(cpu, cpus) {
 811                        per_cpu(l_p_j_ref, cpu) =
 812                                per_cpu(cpu_data, cpu).loops_per_jiffy;
 813                        per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 814                }
 815
 816                if (!global_l_p_j_ref) {
 817                        global_l_p_j_ref = loops_per_jiffy;
 818                        global_l_p_j_ref_freq = freq->old;
 819                }
 820        }
 821
 822        if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 823            (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 824                loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 825                                                global_l_p_j_ref_freq,
 826                                                freq->new);
 827
 828                lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
 829                                    per_cpu(l_p_j_ref_freq, first), freq->new);
 830                for_each_cpu(cpu, cpus)
 831                        per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
 832        }
 833        return NOTIFY_OK;
 834}
 835
 836static struct notifier_block cpufreq_notifier = {
 837        .notifier_call  = cpufreq_callback,
 838};
 839
 840static int __init register_cpufreq_notifier(void)
 841{
 842        return cpufreq_register_notifier(&cpufreq_notifier,
 843                                                CPUFREQ_TRANSITION_NOTIFIER);
 844}
 845core_initcall(register_cpufreq_notifier);
 846
 847#endif
 848
 849static void raise_nmi(cpumask_t *mask)
 850{
 851        __ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask);
 852}
 853
 854void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 855{
 856        nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
 857}
 858