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         secondary_data.task = idle;
 157         sync_cache_w(&secondary_data);
 158
 159         /*
 160          * Now bring the CPU into our world.
 161          */
 162         ret = smp_ops.smp_boot_secondary(cpu, idle);
 163         if (ret == 0) {
 164                 /*
 165                  * CPU was successfully started, wait for it
 166                  * to come online or time out.
 167                  */
 168                 wait_for_completion_timeout(&cpu_running,
 169                                                  msecs_to_jiffies(1000));
 170
 171                 if (!cpu_online(cpu)) {
 172                         pr_crit("CPU%u: failed to come online\n", cpu);
 173                         ret = -EIO;
 174                 }
 175         } else {
 176                 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
 177         }
 178
 179
 180         memset(&secondary_data, 0, sizeof(secondary_data));
 181         return ret;
 182 }
 183
 184 /* platform specific SMP operations */
 185 void __init smp_init_cpus(void)
 186 {
 187         if (smp_ops.smp_init_cpus)
 188                 smp_ops.smp_init_cpus();
 189 }
 190
 191 int platform_can_secondary_boot(void)
 192 {
 193         return !!smp_ops.smp_boot_secondary;
 194 }
 195
 196 int platform_can_cpu_hotplug(void)
 197 {
 198 #ifdef CONFIG_HOTPLUG_CPU
 199         if (smp_ops.cpu_kill)
 200                 return 1;
 201 #endif
 202
 203         return 0;
 204 }
 205
 206 #ifdef CONFIG_HOTPLUG_CPU
 207 static int platform_cpu_kill(unsigned int cpu)
 208 {
 209         if (smp_ops.cpu_kill)
 210                 return smp_ops.cpu_kill(cpu);
 211         return 1;
 212 }
 213
 214 static int platform_cpu_disable(unsigned int cpu)
 215 {
 216         if (smp_ops.cpu_disable)
 217                 return smp_ops.cpu_disable(cpu);
 218
 219         return 0;
 220 }
 221
 222 int platform_can_hotplug_cpu(unsigned int cpu)
 223 {
 224         /* cpu_die must be specified to support hotplug */
 225         if (!smp_ops.cpu_die)
 226                 return 0;
 227
 228         if (smp_ops.cpu_can_disable)
 229                 return smp_ops.cpu_can_disable(cpu);
 230
 231         /*
 232          * By default, allow disabling all CPUs except the first one,
 233          * since this is special on a lot of platforms, e.g. because
 234          * of clock tick interrupts.
 235          */
 236         return cpu != 0;
 237 }
 238
 239 static void ipi_teardown(int cpu)
 240 {
 241         int i;
 242
 243         if (WARN_ON_ONCE(!ipi_irq_base))
 244                 return;
 245
 246         for (i = 0; i < nr_ipi; i++)
 247                 disable_percpu_irq(ipi_irq_base + i);
 248 }
 249
 250 /*
 251  * __cpu_disable runs on the processor to be shutdown.
 252  */
 253 int __cpu_disable(void)
 254 {
 255         unsigned int cpu = smp_processor_id();
 256         int ret;
 257
 258         ret = platform_cpu_disable(cpu);
 259         if (ret)
 260                 return ret;
 261
 262 #ifdef CONFIG_GENERIC_ARCH_TOPOLOGY
 263         remove_cpu_topology(cpu);
 264 #endif
 265
 266         /*
 267          * Take this CPU offline.  Once we clear this, we can't return,
 268          * and we must not schedule until we're ready to give up the cpu.
 269          */
 270         set_cpu_online(cpu, false);
 271         ipi_teardown(cpu);
 272
 273         /*
 274          * OK - migrate IRQs away from this CPU
 275          */
 276         irq_migrate_all_off_this_cpu();
 277
 278         /*
 279          * Flush user cache and TLB mappings, and then remove this CPU
 280          * from the vm mask set of all processes.
 281          *
 282          * Caches are flushed to the Level of Unification Inner Shareable
 283          * to write-back dirty lines to unified caches shared by all CPUs.
 284          */
 285         flush_cache_louis();
 286         local_flush_tlb_all();
 287
 288         return 0;
 289 }
 290
 291 /*
 292  * called on the thread which is asking for a CPU to be shutdown -
 293  * waits until shutdown has completed, or it is timed out.
 294  */
 295 void __cpu_die(unsigned int cpu)
 296 {
 297         if (!cpu_wait_death(cpu, 5)) {
 298                 pr_err("CPU%u: cpu didn't die\n", cpu);
 299                 return;
 300         }
 301         pr_debug("CPU%u: shutdown\n", cpu);
 302
 303         clear_tasks_mm_cpumask(cpu);
 304         /*
 305          * platform_cpu_kill() is generally expected to do the powering off
 306          * and/or cutting of clocks to the dying CPU.  Optionally, this may
 307          * be done by the CPU which is dying in preference to supporting
 308          * this call, but that means there is _no_ synchronisation between
 309          * the requesting CPU and the dying CPU actually losing power.
 310          */
 311         if (!platform_cpu_kill(cpu))
 312                 pr_err("CPU%u: unable to kill\n", cpu);
 313 }
 314
 315 /*
 316  * Called from the idle thread for the CPU which has been shutdown.
 317  *
 318  * Note that we disable IRQs here, but do not re-enable them
 319  * before returning to the caller. This is also the behaviour
 320  * of the other hotplug-cpu capable cores, so presumably coming
 321  * out of idle fixes this.
 322  */
 323 void arch_cpu_idle_dead(void)
 324 {
 325         unsigned int cpu = smp_processor_id();
 326
 327         idle_task_exit();
 328
 329         local_irq_disable();
 330
 331         /*
 332          * Flush the data out of the L1 cache for this CPU.  This must be
 333          * before the completion to ensure that data is safely written out
 334          * before platform_cpu_kill() gets called - which may disable
 335          * *this* CPU and power down its cache.
 336          */
 337         flush_cache_louis();
 338
 339         /*
 340          * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
 341          * this returns, power and/or clocks can be removed at any point
 342          * from this CPU and its cache by platform_cpu_kill().
 343          */
 344         (void)cpu_report_death();
 345
 346         /*
 347          * Ensure that the cache lines associated with that completion are
 348          * written out.  This covers the case where _this_ CPU is doing the
 349          * powering down, to ensure that the completion is visible to the
 350          * CPU waiting for this one.
 351          */
 352         flush_cache_louis();
 353
 354         /*
 355          * The actual CPU shutdown procedure is at least platform (if not
 356          * CPU) specific.  This may remove power, or it may simply spin.
 357          *
 358          * Platforms are generally expected *NOT* to return from this call,
 359          * although there are some which do because they have no way to
 360          * power down the CPU.  These platforms are the _only_ reason we
 361          * have a return path which uses the fragment of assembly below.
 362          *
 363          * The return path should not be used for platforms which can
 364          * power off the CPU.
 365          */
 366         if (smp_ops.cpu_die)
 367                 smp_ops.cpu_die(cpu);
 368
 369         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 370                 cpu);
 371
 372         /*
 373          * Do not return to the idle loop - jump back to the secondary
 374          * cpu initialisation.  There's some initialisation which needs
 375          * to be repeated to undo the effects of taking the CPU offline.
 376          */
 377         __asm__("mov    sp, %0\n"
 378         "       mov     fp, #0\n"
 379         "       mov     r0, %1\n"
 380         "       b       secondary_start_kernel"
 381                 :
 382                 : "r" (task_stack_page(current) + THREAD_SIZE - 8),
 383                   "r" (current)
 384                 : "r0");
 385 }
 386 #endif /* CONFIG_HOTPLUG_CPU */
 387
 388 /*
 389  * Called by both boot and secondaries to move global data into
 390  * per-processor storage.
 391  */
 392 static void smp_store_cpu_info(unsigned int cpuid)
 393 {
 394         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 395
 396         cpu_info->loops_per_jiffy = loops_per_jiffy;
 397         cpu_info->cpuid = read_cpuid_id();
 398
 399         store_cpu_topology(cpuid);
 400         check_cpu_icache_size(cpuid);
 401 }
 402
 403 static void set_current(struct task_struct *cur)
 404 {
 405         /* Set TPIDRURO */
 406         asm("mcr p15, 0, %0, c13, c0, 3" :: "r"(cur) : "memory");
 407 }
 408
 409 /*
 410  * This is the secondary CPU boot entry.  We're using this CPUs
 411  * idle thread stack, but a set of temporary page tables.
 412  */
 413 asmlinkage void secondary_start_kernel(struct task_struct *task)
 414 {
 415         struct mm_struct *mm = &init_mm;
 416         unsigned int cpu;
 417
 418         set_current(task);
 419
 420         secondary_biglittle_init();
 421
 422         /*
 423          * The identity mapping is uncached (strongly ordered), so
 424          * switch away from it before attempting any exclusive accesses.
 425          */
 426         cpu_switch_mm(mm->pgd, mm);
 427         local_flush_bp_all();
 428         enter_lazy_tlb(mm, current);
 429         local_flush_tlb_all();
 430
 431         /*
 432          * All kernel threads share the same mm context; grab a
 433          * reference and switch to it.
 434          */
 435         cpu = smp_processor_id();
 436         mmgrab(mm);
 437         current->active_mm = mm;
 438         cpumask_set_cpu(cpu, mm_cpumask(mm));
 439
 440         cpu_init();
 441
 442 #ifndef CONFIG_MMU
 443         setup_vectors_base();
 444 #endif
 445         pr_debug("CPU%u: Booted secondary processor\n", cpu);
 446
 447         trace_hardirqs_off();
 448
 449         /*
 450          * Give the platform a chance to do its own initialisation.
 451          */
 452         if (smp_ops.smp_secondary_init)
 453                 smp_ops.smp_secondary_init(cpu);
 454
 455         notify_cpu_starting(cpu);
 456
 457         ipi_setup(cpu);
 458
 459         calibrate_delay();
 460
 461         smp_store_cpu_info(cpu);
 462
 463         /*
 464          * OK, now it's safe to let the boot CPU continue.  Wait for
 465          * the CPU migration code to notice that the CPU is online
 466          * before we continue - which happens after __cpu_up returns.
 467          */
 468         set_cpu_online(cpu, true);
 469
 470         check_other_bugs();
 471
 472         complete(&cpu_running);
 473
 474         local_irq_enable();
 475         local_fiq_enable();
 476         local_abt_enable();
 477
 478         /*
 479          * OK, it's off to the idle thread for us
 480          */
 481         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 482 }
 483
 484 void __init smp_cpus_done(unsigned int max_cpus)
 485 {
 486         int cpu;
 487         unsigned long bogosum = 0;
 488
 489         for_each_online_cpu(cpu)
 490                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 491
 492         printk(KERN_INFO "SMP: Total of %d processors activated "
 493                "(%lu.%02lu BogoMIPS).\n",
 494                num_online_cpus(),
 495                bogosum / (500000/HZ),
 496                (bogosum / (5000/HZ)) % 100);
 497
 498         hyp_mode_check();
 499 }
 500
 501 void __init smp_prepare_boot_cpu(void)
 502 {
 503         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 504 }
 505
 506 void __init smp_prepare_cpus(unsigned int max_cpus)
 507 {
 508         unsigned int ncores = num_possible_cpus();
 509
 510         init_cpu_topology();
 511
 512         smp_store_cpu_info(smp_processor_id());
 513
 514         /*
 515          * are we trying to boot more cores than exist?
 516          */
 517         if (max_cpus > ncores)
 518                 max_cpus = ncores;
 519         if (ncores > 1 && max_cpus) {
 520                 /*
 521                  * Initialise the present map, which describes the set of CPUs
 522                  * actually populated at the present time. A platform should
 523                  * re-initialize the map in the platforms smp_prepare_cpus()
 524                  * if present != possible (e.g. physical hotplug).
 525                  */
 526                 init_cpu_present(cpu_possible_mask);
 527
 528                 /*
 529                  * Initialise the SCU if there are more than one CPU
 530                  * and let them know where to start.
 531                  */
 532                 if (smp_ops.smp_prepare_cpus)
 533                         smp_ops.smp_prepare_cpus(max_cpus);
 534         }
 535 }
 536
 537 static const char *ipi_types[NR_IPI] __tracepoint_string = {
 538         [IPI_WAKEUP]            = "CPU wakeup interrupts",
 539         [IPI_TIMER]             = "Timer broadcast interrupts",
 540         [IPI_RESCHEDULE]        = "Rescheduling interrupts",
 541         [IPI_CALL_FUNC]         = "Function call interrupts",
 542         [IPI_CPU_STOP]          = "CPU stop interrupts",
 543         [IPI_IRQ_WORK]          = "IRQ work interrupts",
 544         [IPI_COMPLETION]        = "completion interrupts",
 545 };
 546
 547 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr);
 548
 549 void show_ipi_list(struct seq_file *p, int prec)
 550 {
 551         unsigned int cpu, i;
 552
 553         for (i = 0; i < NR_IPI; i++) {
 554                 if (!ipi_desc[i])
 555                         continue;
 556
 557                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 558
 559                 for_each_online_cpu(cpu)
 560                         seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
 561
 562                 seq_printf(p, " %s\n", ipi_types[i]);
 563         }
 564 }
 565
 566 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 567 {
 568         smp_cross_call(mask, IPI_CALL_FUNC);
 569 }
 570
 571 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 572 {
 573         smp_cross_call(mask, IPI_WAKEUP);
 574 }
 575
 576 void arch_send_call_function_single_ipi(int cpu)
 577 {
 578         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
 579 }
 580
 581 #ifdef CONFIG_IRQ_WORK
 582 void arch_irq_work_raise(void)
 583 {
 584         if (arch_irq_work_has_interrupt())
 585                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 586 }
 587 #endif
 588
 589 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 590 void tick_broadcast(const struct cpumask *mask)
 591 {
 592         smp_cross_call(mask, IPI_TIMER);
 593 }
 594 #endif
 595
 596 static DEFINE_RAW_SPINLOCK(stop_lock);
 597
 598 /*
 599  * ipi_cpu_stop - handle IPI from smp_send_stop()
 600  */
 601 static void ipi_cpu_stop(unsigned int cpu)
 602 {
 603         if (system_state <= SYSTEM_RUNNING) {
 604                 raw_spin_lock(&stop_lock);
 605                 pr_crit("CPU%u: stopping\n", cpu);
 606                 dump_stack();
 607                 raw_spin_unlock(&stop_lock);
 608         }
 609
 610         set_cpu_online(cpu, false);
 611
 612         local_fiq_disable();
 613         local_irq_disable();
 614
 615         while (1) {
 616                 cpu_relax();
 617                 wfe();
 618         }
 619 }
 620
 621 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 622
 623 int register_ipi_completion(struct completion *completion, int cpu)
 624 {
 625         per_cpu(cpu_completion, cpu) = completion;
 626         return IPI_COMPLETION;
 627 }
 628
 629 static void ipi_complete(unsigned int cpu)
 630 {
 631         complete(per_cpu(cpu_completion, cpu));
 632 }
 633
 634 /*
 635  * Main handler for inter-processor interrupts
 636  */
 637 static void do_handle_IPI(int ipinr)
 638 {
 639         unsigned int cpu = smp_processor_id();
 640
 641         if ((unsigned)ipinr < NR_IPI)
 642                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 643
 644         switch (ipinr) {
 645         case IPI_WAKEUP:
 646                 break;
 647
 648 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 649         case IPI_TIMER:
 650                 tick_receive_broadcast();
 651                 break;
 652 #endif
 653
 654         case IPI_RESCHEDULE:
 655                 scheduler_ipi();
 656                 break;
 657
 658         case IPI_CALL_FUNC:
 659                 generic_smp_call_function_interrupt();
 660                 break;
 661
 662         case IPI_CPU_STOP:
 663                 ipi_cpu_stop(cpu);
 664                 break;
 665
 666 #ifdef CONFIG_IRQ_WORK
 667         case IPI_IRQ_WORK:
 668                 irq_work_run();
 669                 break;
 670 #endif
 671
 672         case IPI_COMPLETION:
 673                 ipi_complete(cpu);
 674                 break;
 675
 676         case IPI_CPU_BACKTRACE:
 677                 printk_deferred_enter();
 678                 nmi_cpu_backtrace(get_irq_regs());
 679                 printk_deferred_exit();
 680                 break;
 681
 682         default:
 683                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 684                         cpu, ipinr);
 685                 break;
 686         }
 687
 688         if ((unsigned)ipinr < NR_IPI)
 689                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 690 }
 691
 692 /* Legacy version, should go away once all irqchips have been converted */
 693 void handle_IPI(int ipinr, struct pt_regs *regs)
 694 {
 695         struct pt_regs *old_regs = set_irq_regs(regs);
 696
 697         irq_enter();
 698         do_handle_IPI(ipinr);
 699         irq_exit();
 700
 701         set_irq_regs(old_regs);
 702 }
 703
 704 static irqreturn_t ipi_handler(int irq, void *data)
 705 {
 706         do_handle_IPI(irq - ipi_irq_base);
 707         return IRQ_HANDLED;
 708 }
 709
 710 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 711 {
 712         trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
 713         __ipi_send_mask(ipi_desc[ipinr], target);
 714 }
 715
 716 static void ipi_setup(int cpu)
 717 {
 718         int i;
 719
 720         if (WARN_ON_ONCE(!ipi_irq_base))
 721                 return;
 722
 723         for (i = 0; i < nr_ipi; i++)
 724                 enable_percpu_irq(ipi_irq_base + i, 0);
 725 }
 726
 727 void __init set_smp_ipi_range(int ipi_base, int n)
 728 {
 729         int i;
 730
 731         WARN_ON(n < MAX_IPI);
 732         nr_ipi = min(n, MAX_IPI);
 733
 734         for (i = 0; i < nr_ipi; i++) {
 735                 int err;
 736
 737                 err = request_percpu_irq(ipi_base + i, ipi_handler,
 738                                          "IPI", &irq_stat);
 739                 WARN_ON(err);
 740
 741                 ipi_desc[i] = irq_to_desc(ipi_base + i);
 742                 irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
 743         }
 744
 745         ipi_irq_base = ipi_base;
 746
 747         /* Setup the boot CPU immediately */
 748         ipi_setup(smp_processor_id());
 749 }
 750
 751 void smp_send_reschedule(int cpu)
 752 {
 753         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 754 }
 755
 756 void smp_send_stop(void)
 757 {
 758         unsigned long timeout;
 759         struct cpumask mask;
 760
 761         cpumask_copy(&mask, cpu_online_mask);
 762         cpumask_clear_cpu(smp_processor_id(), &mask);
 763         if (!cpumask_empty(&mask))
 764                 smp_cross_call(&mask, IPI_CPU_STOP);
 765
 766         /* Wait up to one second for other CPUs to stop */
 767         timeout = USEC_PER_SEC;
 768         while (num_online_cpus() > 1 && timeout--)
 769                 udelay(1);
 770
 771         if (num_online_cpus() > 1)
 772                 pr_warn("SMP: failed to stop secondary CPUs\n");
 773 }
 774
 775 /* In case panic() and panic() called at the same time on CPU1 and CPU2,
 776  * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
 777  * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
 778  * kdump fails. So split out the panic_smp_self_stop() and add
 779  * set_cpu_online(smp_processor_id(), false).
 780  */
 781 void panic_smp_self_stop(void)
 782 {
 783         pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
 784                  smp_processor_id());
 785         set_cpu_online(smp_processor_id(), false);
 786         while (1)
 787                 cpu_relax();
 788 }
 789
 790 /*
 791  * not supported here
 792  */
 793 int setup_profiling_timer(unsigned int multiplier)
 794 {
 795         return -EINVAL;
 796 }
 797
 798 #ifdef CONFIG_CPU_FREQ
 799
 800 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 801 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 802 static unsigned long global_l_p_j_ref;
 803 static unsigned long global_l_p_j_ref_freq;
 804
 805 static int cpufreq_callback(struct notifier_block *nb,
 806                                         unsigned long val, void *data)
 807 {
 808         struct cpufreq_freqs *freq = data;
 809         struct cpumask *cpus = freq->policy->cpus;
 810         int cpu, first = cpumask_first(cpus);
 811         unsigned int lpj;
 812
 813         if (freq->flags & CPUFREQ_CONST_LOOPS)
 814                 return NOTIFY_OK;
 815
 816         if (!per_cpu(l_p_j_ref, first)) {
 817                 for_each_cpu(cpu, cpus) {
 818                         per_cpu(l_p_j_ref, cpu) =
 819                                 per_cpu(cpu_data, cpu).loops_per_jiffy;
 820                         per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 821                 }
 822
 823                 if (!global_l_p_j_ref) {
 824                         global_l_p_j_ref = loops_per_jiffy;
 825                         global_l_p_j_ref_freq = freq->old;
 826                 }
 827         }
 828
 829         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 830             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 831                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 832                                                 global_l_p_j_ref_freq,
 833                                                 freq->new);
 834
 835                 lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
 836                                     per_cpu(l_p_j_ref_freq, first), freq->new);
 837                 for_each_cpu(cpu, cpus)
 838                         per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
 839         }
 840         return NOTIFY_OK;
 841 }
 842
 843 static struct notifier_block cpufreq_notifier = {
 844         .notifier_call  = cpufreq_callback,
 845 };
 846
 847 static int __init register_cpufreq_notifier(void)
 848 {
 849         return cpufreq_register_notifier(&cpufreq_notifier,
 850                                                 CPUFREQ_TRANSITION_NOTIFIER);
 851 }
 852 core_initcall(register_cpufreq_notifier);
 853
 854 #endif
 855
 856 static void raise_nmi(cpumask_t *mask)
 857 {
 858         __ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask);
 859 }
 860
 861 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 862 {
 863         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
 864 }