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         if (IS_ENABLED(CONFIG_THREAD_INFO_IN_TASK))
 158                 task_thread_info(idle)->cpu = cpu;
 159
 160         sync_cache_w(&secondary_data);
 161
 162         /*
 163          * Now bring the CPU into our world.
 164          */
 165         ret = smp_ops.smp_boot_secondary(cpu, idle);
 166         if (ret == 0) {
 167                 /*
 168                  * CPU was successfully started, wait for it
 169                  * to come online or time out.
 170                  */
 171                 wait_for_completion_timeout(&cpu_running,
 172                                                  msecs_to_jiffies(1000));
 173
 174                 if (!cpu_online(cpu)) {
 175                         pr_crit("CPU%u: failed to come online\n", cpu);
 176                         ret = -EIO;
 177                 }
 178         } else {
 179                 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
 180         }
 181
 182
 183         memset(&secondary_data, 0, sizeof(secondary_data));
 184         return ret;
 185 }
 186
 187 /* platform specific SMP operations */
 188 void __init smp_init_cpus(void)
 189 {
 190         if (smp_ops.smp_init_cpus)
 191                 smp_ops.smp_init_cpus();
 192 }
 193
 194 int platform_can_secondary_boot(void)
 195 {
 196         return !!smp_ops.smp_boot_secondary;
 197 }
 198
 199 int platform_can_cpu_hotplug(void)
 200 {
 201 #ifdef CONFIG_HOTPLUG_CPU
 202         if (smp_ops.cpu_kill)
 203                 return 1;
 204 #endif
 205
 206         return 0;
 207 }
 208
 209 #ifdef CONFIG_HOTPLUG_CPU
 210 static int platform_cpu_kill(unsigned int cpu)
 211 {
 212         if (smp_ops.cpu_kill)
 213                 return smp_ops.cpu_kill(cpu);
 214         return 1;
 215 }
 216
 217 static int platform_cpu_disable(unsigned int cpu)
 218 {
 219         if (smp_ops.cpu_disable)
 220                 return smp_ops.cpu_disable(cpu);
 221
 222         return 0;
 223 }
 224
 225 int platform_can_hotplug_cpu(unsigned int cpu)
 226 {
 227         /* cpu_die must be specified to support hotplug */
 228         if (!smp_ops.cpu_die)
 229                 return 0;
 230
 231         if (smp_ops.cpu_can_disable)
 232                 return smp_ops.cpu_can_disable(cpu);
 233
 234         /*
 235          * By default, allow disabling all CPUs except the first one,
 236          * since this is special on a lot of platforms, e.g. because
 237          * of clock tick interrupts.
 238          */
 239         return cpu != 0;
 240 }
 241
 242 static void ipi_teardown(int cpu)
 243 {
 244         int i;
 245
 246         if (WARN_ON_ONCE(!ipi_irq_base))
 247                 return;
 248
 249         for (i = 0; i < nr_ipi; i++)
 250                 disable_percpu_irq(ipi_irq_base + i);
 251 }
 252
 253 /*
 254  * __cpu_disable runs on the processor to be shutdown.
 255  */
 256 int __cpu_disable(void)
 257 {
 258         unsigned int cpu = smp_processor_id();
 259         int ret;
 260
 261         ret = platform_cpu_disable(cpu);
 262         if (ret)
 263                 return ret;
 264
 265 #ifdef CONFIG_GENERIC_ARCH_TOPOLOGY
 266         remove_cpu_topology(cpu);
 267 #endif
 268
 269         /*
 270          * Take this CPU offline.  Once we clear this, we can't return,
 271          * and we must not schedule until we're ready to give up the cpu.
 272          */
 273         set_cpu_online(cpu, false);
 274         ipi_teardown(cpu);
 275
 276         /*
 277          * OK - migrate IRQs away from this CPU
 278          */
 279         irq_migrate_all_off_this_cpu();
 280
 281         /*
 282          * Flush user cache and TLB mappings, and then remove this CPU
 283          * from the vm mask set of all processes.
 284          *
 285          * Caches are flushed to the Level of Unification Inner Shareable
 286          * to write-back dirty lines to unified caches shared by all CPUs.
 287          */
 288         flush_cache_louis();
 289         local_flush_tlb_all();
 290
 291         return 0;
 292 }
 293
 294 /*
 295  * called on the thread which is asking for a CPU to be shutdown -
 296  * waits until shutdown has completed, or it is timed out.
 297  */
 298 void __cpu_die(unsigned int cpu)
 299 {
 300         if (!cpu_wait_death(cpu, 5)) {
 301                 pr_err("CPU%u: cpu didn't die\n", cpu);
 302                 return;
 303         }
 304         pr_debug("CPU%u: shutdown\n", cpu);
 305
 306         clear_tasks_mm_cpumask(cpu);
 307         /*
 308          * platform_cpu_kill() is generally expected to do the powering off
 309          * and/or cutting of clocks to the dying CPU.  Optionally, this may
 310          * be done by the CPU which is dying in preference to supporting
 311          * this call, but that means there is _no_ synchronisation between
 312          * the requesting CPU and the dying CPU actually losing power.
 313          */
 314         if (!platform_cpu_kill(cpu))
 315                 pr_err("CPU%u: unable to kill\n", cpu);
 316 }
 317
 318 /*
 319  * Called from the idle thread for the CPU which has been shutdown.
 320  *
 321  * Note that we disable IRQs here, but do not re-enable them
 322  * before returning to the caller. This is also the behaviour
 323  * of the other hotplug-cpu capable cores, so presumably coming
 324  * out of idle fixes this.
 325  */
 326 void arch_cpu_idle_dead(void)
 327 {
 328         unsigned int cpu = smp_processor_id();
 329
 330         idle_task_exit();
 331
 332         local_irq_disable();
 333
 334         /*
 335          * Flush the data out of the L1 cache for this CPU.  This must be
 336          * before the completion to ensure that data is safely written out
 337          * before platform_cpu_kill() gets called - which may disable
 338          * *this* CPU and power down its cache.
 339          */
 340         flush_cache_louis();
 341
 342         /*
 343          * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
 344          * this returns, power and/or clocks can be removed at any point
 345          * from this CPU and its cache by platform_cpu_kill().
 346          */
 347         (void)cpu_report_death();
 348
 349         /*
 350          * Ensure that the cache lines associated with that completion are
 351          * written out.  This covers the case where _this_ CPU is doing the
 352          * powering down, to ensure that the completion is visible to the
 353          * CPU waiting for this one.
 354          */
 355         flush_cache_louis();
 356
 357         /*
 358          * The actual CPU shutdown procedure is at least platform (if not
 359          * CPU) specific.  This may remove power, or it may simply spin.
 360          *
 361          * Platforms are generally expected *NOT* to return from this call,
 362          * although there are some which do because they have no way to
 363          * power down the CPU.  These platforms are the _only_ reason we
 364          * have a return path which uses the fragment of assembly below.
 365          *
 366          * The return path should not be used for platforms which can
 367          * power off the CPU.
 368          */
 369         if (smp_ops.cpu_die)
 370                 smp_ops.cpu_die(cpu);
 371
 372         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 373                 cpu);
 374
 375         /*
 376          * Do not return to the idle loop - jump back to the secondary
 377          * cpu initialisation.  There's some initialisation which needs
 378          * to be repeated to undo the effects of taking the CPU offline.
 379          */
 380         __asm__("mov    sp, %0\n"
 381         "       mov     fp, #0\n"
 382         "       mov     r0, %1\n"
 383         "       b       secondary_start_kernel"
 384                 :
 385                 : "r" (task_stack_page(current) + THREAD_SIZE - 8),
 386                   "r" (current)
 387                 : "r0");
 388 }
 389 #endif /* CONFIG_HOTPLUG_CPU */
 390
 391 /*
 392  * Called by both boot and secondaries to move global data into
 393  * per-processor storage.
 394  */
 395 static void smp_store_cpu_info(unsigned int cpuid)
 396 {
 397         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 398
 399         cpu_info->loops_per_jiffy = loops_per_jiffy;
 400         cpu_info->cpuid = read_cpuid_id();
 401
 402         store_cpu_topology(cpuid);
 403         check_cpu_icache_size(cpuid);
 404 }
 405
 406 /*
 407  * This is the secondary CPU boot entry.  We're using this CPUs
 408  * idle thread stack, but a set of temporary page tables.
 409  */
 410 asmlinkage void secondary_start_kernel(struct task_struct *task)
 411 {
 412         struct mm_struct *mm = &init_mm;
 413         unsigned int cpu;
 414
 415         set_current(task);
 416
 417         secondary_biglittle_init();
 418
 419         /*
 420          * The identity mapping is uncached (strongly ordered), so
 421          * switch away from it before attempting any exclusive accesses.
 422          */
 423         cpu_switch_mm(mm->pgd, mm);
 424         local_flush_bp_all();
 425         enter_lazy_tlb(mm, current);
 426         local_flush_tlb_all();
 427
 428         /*
 429          * All kernel threads share the same mm context; grab a
 430          * reference and switch to it.
 431          */
 432         cpu = smp_processor_id();
 433         mmgrab(mm);
 434         current->active_mm = mm;
 435         cpumask_set_cpu(cpu, mm_cpumask(mm));
 436
 437         cpu_init();
 438
 439 #ifndef CONFIG_MMU
 440         setup_vectors_base();
 441 #endif
 442         pr_debug("CPU%u: Booted secondary processor\n", cpu);
 443
 444         trace_hardirqs_off();
 445
 446         /*
 447          * Give the platform a chance to do its own initialisation.
 448          */
 449         if (smp_ops.smp_secondary_init)
 450                 smp_ops.smp_secondary_init(cpu);
 451
 452         notify_cpu_starting(cpu);
 453
 454         ipi_setup(cpu);
 455
 456         calibrate_delay();
 457
 458         smp_store_cpu_info(cpu);
 459
 460         /*
 461          * OK, now it's safe to let the boot CPU continue.  Wait for
 462          * the CPU migration code to notice that the CPU is online
 463          * before we continue - which happens after __cpu_up returns.
 464          */
 465         set_cpu_online(cpu, true);
 466
 467         check_other_bugs();
 468
 469         complete(&cpu_running);
 470
 471         local_irq_enable();
 472         local_fiq_enable();
 473         local_abt_enable();
 474
 475         /*
 476          * OK, it's off to the idle thread for us
 477          */
 478         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 479 }
 480
 481 void __init smp_cpus_done(unsigned int max_cpus)
 482 {
 483         int cpu;
 484         unsigned long bogosum = 0;
 485
 486         for_each_online_cpu(cpu)
 487                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 488
 489         printk(KERN_INFO "SMP: Total of %d processors activated "
 490                "(%lu.%02lu BogoMIPS).\n",
 491                num_online_cpus(),
 492                bogosum / (500000/HZ),
 493                (bogosum / (5000/HZ)) % 100);
 494
 495         hyp_mode_check();
 496 }
 497
 498 void __init smp_prepare_boot_cpu(void)
 499 {
 500         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 501 }
 502
 503 void __init smp_prepare_cpus(unsigned int max_cpus)
 504 {
 505         unsigned int ncores = num_possible_cpus();
 506
 507         init_cpu_topology();
 508
 509         smp_store_cpu_info(smp_processor_id());
 510
 511         /*
 512          * are we trying to boot more cores than exist?
 513          */
 514         if (max_cpus > ncores)
 515                 max_cpus = ncores;
 516         if (ncores > 1 && max_cpus) {
 517                 /*
 518                  * Initialise the present map, which describes the set of CPUs
 519                  * actually populated at the present time. A platform should
 520                  * re-initialize the map in the platforms smp_prepare_cpus()
 521                  * if present != possible (e.g. physical hotplug).
 522                  */
 523                 init_cpu_present(cpu_possible_mask);
 524
 525                 /*
 526                  * Initialise the SCU if there are more than one CPU
 527                  * and let them know where to start.
 528                  */
 529                 if (smp_ops.smp_prepare_cpus)
 530                         smp_ops.smp_prepare_cpus(max_cpus);
 531         }
 532 }
 533
 534 static const char *ipi_types[NR_IPI] __tracepoint_string = {
 535         [IPI_WAKEUP]            = "CPU wakeup interrupts",
 536         [IPI_TIMER]             = "Timer broadcast interrupts",
 537         [IPI_RESCHEDULE]        = "Rescheduling interrupts",
 538         [IPI_CALL_FUNC]         = "Function call interrupts",
 539         [IPI_CPU_STOP]          = "CPU stop interrupts",
 540         [IPI_IRQ_WORK]          = "IRQ work interrupts",
 541         [IPI_COMPLETION]        = "completion interrupts",
 542 };
 543
 544 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr);
 545
 546 void show_ipi_list(struct seq_file *p, int prec)
 547 {
 548         unsigned int cpu, i;
 549
 550         for (i = 0; i < NR_IPI; i++) {
 551                 if (!ipi_desc[i])
 552                         continue;
 553
 554                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 555
 556                 for_each_online_cpu(cpu)
 557                         seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
 558
 559                 seq_printf(p, " %s\n", ipi_types[i]);
 560         }
 561 }
 562
 563 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 564 {
 565         smp_cross_call(mask, IPI_CALL_FUNC);
 566 }
 567
 568 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 569 {
 570         smp_cross_call(mask, IPI_WAKEUP);
 571 }
 572
 573 void arch_send_call_function_single_ipi(int cpu)
 574 {
 575         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
 576 }
 577
 578 #ifdef CONFIG_IRQ_WORK
 579 void arch_irq_work_raise(void)
 580 {
 581         if (arch_irq_work_has_interrupt())
 582                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 583 }
 584 #endif
 585
 586 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 587 void tick_broadcast(const struct cpumask *mask)
 588 {
 589         smp_cross_call(mask, IPI_TIMER);
 590 }
 591 #endif
 592
 593 static DEFINE_RAW_SPINLOCK(stop_lock);
 594
 595 /*
 596  * ipi_cpu_stop - handle IPI from smp_send_stop()
 597  */
 598 static void ipi_cpu_stop(unsigned int cpu)
 599 {
 600         if (system_state <= SYSTEM_RUNNING) {
 601                 raw_spin_lock(&stop_lock);
 602                 pr_crit("CPU%u: stopping\n", cpu);
 603                 dump_stack();
 604                 raw_spin_unlock(&stop_lock);
 605         }
 606
 607         set_cpu_online(cpu, false);
 608
 609         local_fiq_disable();
 610         local_irq_disable();
 611
 612         while (1) {
 613                 cpu_relax();
 614                 wfe();
 615         }
 616 }
 617
 618 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 619
 620 int register_ipi_completion(struct completion *completion, int cpu)
 621 {
 622         per_cpu(cpu_completion, cpu) = completion;
 623         return IPI_COMPLETION;
 624 }
 625
 626 static void ipi_complete(unsigned int cpu)
 627 {
 628         complete(per_cpu(cpu_completion, cpu));
 629 }
 630
 631 /*
 632  * Main handler for inter-processor interrupts
 633  */
 634 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 635 {
 636         handle_IPI(ipinr, regs);
 637 }
 638
 639 static void do_handle_IPI(int ipinr)
 640 {
 641         unsigned int cpu = smp_processor_id();
 642
 643         if ((unsigned)ipinr < NR_IPI)
 644                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 645
 646         switch (ipinr) {
 647         case IPI_WAKEUP:
 648                 break;
 649
 650 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 651         case IPI_TIMER:
 652                 tick_receive_broadcast();
 653                 break;
 654 #endif
 655
 656         case IPI_RESCHEDULE:
 657                 scheduler_ipi();
 658                 break;
 659
 660         case IPI_CALL_FUNC:
 661                 generic_smp_call_function_interrupt();
 662                 break;
 663
 664         case IPI_CPU_STOP:
 665                 ipi_cpu_stop(cpu);
 666                 break;
 667
 668 #ifdef CONFIG_IRQ_WORK
 669         case IPI_IRQ_WORK:
 670                 irq_work_run();
 671                 break;
 672 #endif
 673
 674         case IPI_COMPLETION:
 675                 ipi_complete(cpu);
 676                 break;
 677
 678         case IPI_CPU_BACKTRACE:
 679                 printk_deferred_enter();
 680                 nmi_cpu_backtrace(get_irq_regs());
 681                 printk_deferred_exit();
 682                 break;
 683
 684         default:
 685                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 686                         cpu, ipinr);
 687                 break;
 688         }
 689
 690         if ((unsigned)ipinr < NR_IPI)
 691                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 692 }
 693
 694 /* Legacy version, should go away once all irqchips have been converted */
 695 void handle_IPI(int ipinr, struct pt_regs *regs)
 696 {
 697         struct pt_regs *old_regs = set_irq_regs(regs);
 698
 699         irq_enter();
 700         do_handle_IPI(ipinr);
 701         irq_exit();
 702
 703         set_irq_regs(old_regs);
 704 }
 705
 706 static irqreturn_t ipi_handler(int irq, void *data)
 707 {
 708         do_handle_IPI(irq - ipi_irq_base);
 709         return IRQ_HANDLED;
 710 }
 711
 712 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 713 {
 714         trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
 715         __ipi_send_mask(ipi_desc[ipinr], target);
 716 }
 717
 718 static void ipi_setup(int cpu)
 719 {
 720         int i;
 721
 722         if (WARN_ON_ONCE(!ipi_irq_base))
 723                 return;
 724
 725         for (i = 0; i < nr_ipi; i++)
 726                 enable_percpu_irq(ipi_irq_base + i, 0);
 727 }
 728
 729 void __init set_smp_ipi_range(int ipi_base, int n)
 730 {
 731         int i;
 732
 733         WARN_ON(n < MAX_IPI);
 734         nr_ipi = min(n, MAX_IPI);
 735
 736         for (i = 0; i < nr_ipi; i++) {
 737                 int err;
 738
 739                 err = request_percpu_irq(ipi_base + i, ipi_handler,
 740                                          "IPI", &irq_stat);
 741                 WARN_ON(err);
 742
 743                 ipi_desc[i] = irq_to_desc(ipi_base + i);
 744                 irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
 745         }
 746
 747         ipi_irq_base = ipi_base;
 748
 749         /* Setup the boot CPU immediately */
 750         ipi_setup(smp_processor_id());
 751 }
 752
 753 void smp_send_reschedule(int cpu)
 754 {
 755         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 756 }
 757
 758 void smp_send_stop(void)
 759 {
 760         unsigned long timeout;
 761         struct cpumask mask;
 762
 763         cpumask_copy(&mask, cpu_online_mask);
 764         cpumask_clear_cpu(smp_processor_id(), &mask);
 765         if (!cpumask_empty(&mask))
 766                 smp_cross_call(&mask, IPI_CPU_STOP);
 767
 768         /* Wait up to one second for other CPUs to stop */
 769         timeout = USEC_PER_SEC;
 770         while (num_online_cpus() > 1 && timeout--)
 771                 udelay(1);
 772
 773         if (num_online_cpus() > 1)
 774                 pr_warn("SMP: failed to stop secondary CPUs\n");
 775 }
 776
 777 /* In case panic() and panic() called at the same time on CPU1 and CPU2,
 778  * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
 779  * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
 780  * kdump fails. So split out the panic_smp_self_stop() and add
 781  * set_cpu_online(smp_processor_id(), false).
 782  */
 783 void panic_smp_self_stop(void)
 784 {
 785         pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
 786                  smp_processor_id());
 787         set_cpu_online(smp_processor_id(), false);
 788         while (1)
 789                 cpu_relax();
 790 }
 791
 792 /*
 793  * not supported here
 794  */
 795 int setup_profiling_timer(unsigned int multiplier)
 796 {
 797         return -EINVAL;
 798 }
 799
 800 #ifdef CONFIG_CPU_FREQ
 801
 802 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 803 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 804 static unsigned long global_l_p_j_ref;
 805 static unsigned long global_l_p_j_ref_freq;
 806
 807 static int cpufreq_callback(struct notifier_block *nb,
 808                                         unsigned long val, void *data)
 809 {
 810         struct cpufreq_freqs *freq = data;
 811         struct cpumask *cpus = freq->policy->cpus;
 812         int cpu, first = cpumask_first(cpus);
 813         unsigned int lpj;
 814
 815         if (freq->flags & CPUFREQ_CONST_LOOPS)
 816                 return NOTIFY_OK;
 817
 818         if (!per_cpu(l_p_j_ref, first)) {
 819                 for_each_cpu(cpu, cpus) {
 820                         per_cpu(l_p_j_ref, cpu) =
 821                                 per_cpu(cpu_data, cpu).loops_per_jiffy;
 822                         per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 823                 }
 824
 825                 if (!global_l_p_j_ref) {
 826                         global_l_p_j_ref = loops_per_jiffy;
 827                         global_l_p_j_ref_freq = freq->old;
 828                 }
 829         }
 830
 831         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 832             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 833                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 834                                                 global_l_p_j_ref_freq,
 835                                                 freq->new);
 836
 837                 lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
 838                                     per_cpu(l_p_j_ref_freq, first), freq->new);
 839                 for_each_cpu(cpu, cpus)
 840                         per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
 841         }
 842         return NOTIFY_OK;
 843 }
 844
 845 static struct notifier_block cpufreq_notifier = {
 846         .notifier_call  = cpufreq_callback,
 847 };
 848
 849 static int __init register_cpufreq_notifier(void)
 850 {
 851         return cpufreq_register_notifier(&cpufreq_notifier,
 852                                                 CPUFREQ_TRANSITION_NOTIFIER);
 853 }
 854 core_initcall(register_cpufreq_notifier);
 855
 856 #endif
 857
 858 static void raise_nmi(cpumask_t *mask)
 859 {
 860         __ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask);
 861 }
 862
 863 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 864 {
 865         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
 866 }