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 #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  */
  59 struct secondary_data secondary_data;
  60
  61 enum 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
  83 static int ipi_irq_base __read_mostly;
  84 static int nr_ipi __read_mostly = NR_IPI;
  85 static struct irq_desc *ipi_desc[MAX_IPI] __read_mostly;
  86
  87 static void ipi_setup(int cpu);
  88
  89 static DECLARE_COMPLETION(cpu_running);
  90
  91 static struct smp_operations smp_ops __ro_after_init;
  92
  93 void __init smp_set_ops(const struct smp_operations *ops)
  94 {
  95         if (ops)
  96                 smp_ops = *ops;
  97 };
  98
  99 static 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)
 109 static 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
 117 static void secondary_biglittle_init(void)
 118 {
 119         init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
 120 }
 121 #else
 122 static int secondary_biglittle_prepare(unsigned int cpu)
 123 {
 124         return 0;
 125 }
 126
 127 static void secondary_biglittle_init(void)
 128 {
 129 }
 130 #endif
 131
 132 int __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 */
 184 void __init smp_init_cpus(void)
 185 {
 186         if (smp_ops.smp_init_cpus)
 187                 smp_ops.smp_init_cpus();
 188 }
 189
 190 int platform_can_secondary_boot(void)
 191 {
 192         return !!smp_ops.smp_boot_secondary;
 193 }
 194
 195 int 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
 206 static 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
 213 static 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
 221 int 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
 238 static 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  */
 252 int __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  */
 294 void __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  */
 322 void 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  */
 388 static 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  */
 403 asmlinkage 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         preempt_disable();
 436         trace_hardirqs_off();
 437
 438         /*
 439          * Give the platform a chance to do its own initialisation.
 440          */
 441         if (smp_ops.smp_secondary_init)
 442                 smp_ops.smp_secondary_init(cpu);
 443
 444         notify_cpu_starting(cpu);
 445
 446         ipi_setup(cpu);
 447
 448         calibrate_delay();
 449
 450         smp_store_cpu_info(cpu);
 451
 452         /*
 453          * OK, now it's safe to let the boot CPU continue.  Wait for
 454          * the CPU migration code to notice that the CPU is online
 455          * before we continue - which happens after __cpu_up returns.
 456          */
 457         set_cpu_online(cpu, true);
 458
 459         check_other_bugs();
 460
 461         complete(&cpu_running);
 462
 463         local_irq_enable();
 464         local_fiq_enable();
 465         local_abt_enable();
 466
 467         /*
 468          * OK, it's off to the idle thread for us
 469          */
 470         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 471 }
 472
 473 void __init smp_cpus_done(unsigned int max_cpus)
 474 {
 475         int cpu;
 476         unsigned long bogosum = 0;
 477
 478         for_each_online_cpu(cpu)
 479                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 480
 481         printk(KERN_INFO "SMP: Total of %d processors activated "
 482                "(%lu.%02lu BogoMIPS).\n",
 483                num_online_cpus(),
 484                bogosum / (500000/HZ),
 485                (bogosum / (5000/HZ)) % 100);
 486
 487         hyp_mode_check();
 488 }
 489
 490 void __init smp_prepare_boot_cpu(void)
 491 {
 492         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 493 }
 494
 495 void __init smp_prepare_cpus(unsigned int max_cpus)
 496 {
 497         unsigned int ncores = num_possible_cpus();
 498
 499         init_cpu_topology();
 500
 501         smp_store_cpu_info(smp_processor_id());
 502
 503         /*
 504          * are we trying to boot more cores than exist?
 505          */
 506         if (max_cpus > ncores)
 507                 max_cpus = ncores;
 508         if (ncores > 1 && max_cpus) {
 509                 /*
 510                  * Initialise the present map, which describes the set of CPUs
 511                  * actually populated at the present time. A platform should
 512                  * re-initialize the map in the platforms smp_prepare_cpus()
 513                  * if present != possible (e.g. physical hotplug).
 514                  */
 515                 init_cpu_present(cpu_possible_mask);
 516
 517                 /*
 518                  * Initialise the SCU if there are more than one CPU
 519                  * and let them know where to start.
 520                  */
 521                 if (smp_ops.smp_prepare_cpus)
 522                         smp_ops.smp_prepare_cpus(max_cpus);
 523         }
 524 }
 525
 526 static const char *ipi_types[NR_IPI] __tracepoint_string = {
 527         [IPI_WAKEUP]            = "CPU wakeup interrupts",
 528         [IPI_TIMER]             = "Timer broadcast interrupts",
 529         [IPI_RESCHEDULE]        = "Rescheduling interrupts",
 530         [IPI_CALL_FUNC]         = "Function call interrupts",
 531         [IPI_CPU_STOP]          = "CPU stop interrupts",
 532         [IPI_IRQ_WORK]          = "IRQ work interrupts",
 533         [IPI_COMPLETION]        = "completion interrupts",
 534 };
 535
 536 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr);
 537
 538 void show_ipi_list(struct seq_file *p, int prec)
 539 {
 540         unsigned int cpu, i;
 541
 542         for (i = 0; i < NR_IPI; i++) {
 543                 unsigned int irq;
 544
 545                 if (!ipi_desc[i])
 546                         continue;
 547
 548                 irq = irq_desc_get_irq(ipi_desc[i]);
 549                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 550
 551                 for_each_online_cpu(cpu)
 552                         seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
 553
 554                 seq_printf(p, " %s\n", ipi_types[i]);
 555         }
 556 }
 557
 558 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 559 {
 560         smp_cross_call(mask, IPI_CALL_FUNC);
 561 }
 562
 563 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 564 {
 565         smp_cross_call(mask, IPI_WAKEUP);
 566 }
 567
 568 void arch_send_call_function_single_ipi(int cpu)
 569 {
 570         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
 571 }
 572
 573 #ifdef CONFIG_IRQ_WORK
 574 void arch_irq_work_raise(void)
 575 {
 576         if (arch_irq_work_has_interrupt())
 577                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 578 }
 579 #endif
 580
 581 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 582 void tick_broadcast(const struct cpumask *mask)
 583 {
 584         smp_cross_call(mask, IPI_TIMER);
 585 }
 586 #endif
 587
 588 static DEFINE_RAW_SPINLOCK(stop_lock);
 589
 590 /*
 591  * ipi_cpu_stop - handle IPI from smp_send_stop()
 592  */
 593 static void ipi_cpu_stop(unsigned int cpu)
 594 {
 595         if (system_state <= SYSTEM_RUNNING) {
 596                 raw_spin_lock(&stop_lock);
 597                 pr_crit("CPU%u: stopping\n", cpu);
 598                 dump_stack();
 599                 raw_spin_unlock(&stop_lock);
 600         }
 601
 602         set_cpu_online(cpu, false);
 603
 604         local_fiq_disable();
 605         local_irq_disable();
 606
 607         while (1) {
 608                 cpu_relax();
 609                 wfe();
 610         }
 611 }
 612
 613 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 614
 615 int register_ipi_completion(struct completion *completion, int cpu)
 616 {
 617         per_cpu(cpu_completion, cpu) = completion;
 618         return IPI_COMPLETION;
 619 }
 620
 621 static void ipi_complete(unsigned int cpu)
 622 {
 623         complete(per_cpu(cpu_completion, cpu));
 624 }
 625
 626 /*
 627  * Main handler for inter-processor interrupts
 628  */
 629 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 630 {
 631         handle_IPI(ipinr, regs);
 632 }
 633
 634 static void do_handle_IPI(int ipinr)
 635 {
 636         unsigned int cpu = smp_processor_id();
 637
 638         if ((unsigned)ipinr < NR_IPI)
 639                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 640
 641         switch (ipinr) {
 642         case IPI_WAKEUP:
 643                 break;
 644
 645 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 646         case IPI_TIMER:
 647                 tick_receive_broadcast();
 648                 break;
 649 #endif
 650
 651         case IPI_RESCHEDULE:
 652                 scheduler_ipi();
 653                 break;
 654
 655         case IPI_CALL_FUNC:
 656                 generic_smp_call_function_interrupt();
 657                 break;
 658
 659         case IPI_CPU_STOP:
 660                 ipi_cpu_stop(cpu);
 661                 break;
 662
 663 #ifdef CONFIG_IRQ_WORK
 664         case IPI_IRQ_WORK:
 665                 irq_work_run();
 666                 break;
 667 #endif
 668
 669         case IPI_COMPLETION:
 670                 ipi_complete(cpu);
 671                 break;
 672
 673         case IPI_CPU_BACKTRACE:
 674                 printk_nmi_enter();
 675                 nmi_cpu_backtrace(get_irq_regs());
 676                 printk_nmi_exit();
 677                 break;
 678
 679         default:
 680                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 681                         cpu, ipinr);
 682                 break;
 683         }
 684
 685         if ((unsigned)ipinr < NR_IPI)
 686                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 687 }
 688
 689 /* Legacy version, should go away once all irqchips have been converted */
 690 void handle_IPI(int ipinr, struct pt_regs *regs)
 691 {
 692         struct pt_regs *old_regs = set_irq_regs(regs);
 693
 694         irq_enter();
 695         do_handle_IPI(ipinr);
 696         irq_exit();
 697
 698         set_irq_regs(old_regs);
 699 }
 700
 701 static irqreturn_t ipi_handler(int irq, void *data)
 702 {
 703         do_handle_IPI(irq - ipi_irq_base);
 704         return IRQ_HANDLED;
 705 }
 706
 707 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 708 {
 709         trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
 710         __ipi_send_mask(ipi_desc[ipinr], target);
 711 }
 712
 713 static void ipi_setup(int cpu)
 714 {
 715         int i;
 716
 717         if (WARN_ON_ONCE(!ipi_irq_base))
 718                 return;
 719
 720         for (i = 0; i < nr_ipi; i++)
 721                 enable_percpu_irq(ipi_irq_base + i, 0);
 722 }
 723
 724 void __init set_smp_ipi_range(int ipi_base, int n)
 725 {
 726         int i;
 727
 728         WARN_ON(n < MAX_IPI);
 729         nr_ipi = min(n, MAX_IPI);
 730
 731         for (i = 0; i < nr_ipi; i++) {
 732                 int err;
 733
 734                 err = request_percpu_irq(ipi_base + i, ipi_handler,
 735                                          "IPI", &irq_stat);
 736                 WARN_ON(err);
 737
 738                 ipi_desc[i] = irq_to_desc(ipi_base + i);
 739                 irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
 740         }
 741
 742         ipi_irq_base = ipi_base;
 743
 744         /* Setup the boot CPU immediately */
 745         ipi_setup(smp_processor_id());
 746 }
 747
 748 void smp_send_reschedule(int cpu)
 749 {
 750         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 751 }
 752
 753 void smp_send_stop(void)
 754 {
 755         unsigned long timeout;
 756         struct cpumask mask;
 757
 758         cpumask_copy(&mask, cpu_online_mask);
 759         cpumask_clear_cpu(smp_processor_id(), &mask);
 760         if (!cpumask_empty(&mask))
 761                 smp_cross_call(&mask, IPI_CPU_STOP);
 762
 763         /* Wait up to one second for other CPUs to stop */
 764         timeout = USEC_PER_SEC;
 765         while (num_online_cpus() > 1 && timeout--)
 766                 udelay(1);
 767
 768         if (num_online_cpus() > 1)
 769                 pr_warn("SMP: failed to stop secondary CPUs\n");
 770 }
 771
 772 /* In case panic() and panic() called at the same time on CPU1 and CPU2,
 773  * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
 774  * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
 775  * kdump fails. So split out the panic_smp_self_stop() and add
 776  * set_cpu_online(smp_processor_id(), false).
 777  */
 778 void panic_smp_self_stop(void)
 779 {
 780         pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
 781                  smp_processor_id());
 782         set_cpu_online(smp_processor_id(), false);
 783         while (1)
 784                 cpu_relax();
 785 }
 786
 787 /*
 788  * not supported here
 789  */
 790 int setup_profiling_timer(unsigned int multiplier)
 791 {
 792         return -EINVAL;
 793 }
 794
 795 #ifdef CONFIG_CPU_FREQ
 796
 797 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 798 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 799 static unsigned long global_l_p_j_ref;
 800 static unsigned long global_l_p_j_ref_freq;
 801
 802 static int cpufreq_callback(struct notifier_block *nb,
 803                                         unsigned long val, void *data)
 804 {
 805         struct cpufreq_freqs *freq = data;
 806         struct cpumask *cpus = freq->policy->cpus;
 807         int cpu, first = cpumask_first(cpus);
 808         unsigned int lpj;
 809
 810         if (freq->flags & CPUFREQ_CONST_LOOPS)
 811                 return NOTIFY_OK;
 812
 813         if (!per_cpu(l_p_j_ref, first)) {
 814                 for_each_cpu(cpu, cpus) {
 815                         per_cpu(l_p_j_ref, cpu) =
 816                                 per_cpu(cpu_data, cpu).loops_per_jiffy;
 817                         per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 818                 }
 819
 820                 if (!global_l_p_j_ref) {
 821                         global_l_p_j_ref = loops_per_jiffy;
 822                         global_l_p_j_ref_freq = freq->old;
 823                 }
 824         }
 825
 826         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 827             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 828                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 829                                                 global_l_p_j_ref_freq,
 830                                                 freq->new);
 831
 832                 lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
 833                                     per_cpu(l_p_j_ref_freq, first), freq->new);
 834                 for_each_cpu(cpu, cpus)
 835                         per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
 836         }
 837         return NOTIFY_OK;
 838 }
 839
 840 static struct notifier_block cpufreq_notifier = {
 841         .notifier_call  = cpufreq_callback,
 842 };
 843
 844 static int __init register_cpufreq_notifier(void)
 845 {
 846         return cpufreq_register_notifier(&cpufreq_notifier,
 847                                                 CPUFREQ_TRANSITION_NOTIFIER);
 848 }
 849 core_initcall(register_cpufreq_notifier);
 850
 851 #endif
 852
 853 static void raise_nmi(cpumask_t *mask)
 854 {
 855         __ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask);
 856 }
 857
 858 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 859 {
 860         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
 861 }