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 #include <trace/events/ipi.h>
  52
  53 /*
  54  * as from 2.5, kernels no longer have an init_tasks structure
  55  * so we need some other way of telling a new secondary core
  56  * where to place its SVC stack
  57  */
  58 struct secondary_data secondary_data;
  59
  60 enum ipi_msg_type {
  61         IPI_WAKEUP,
  62         IPI_TIMER,
  63         IPI_RESCHEDULE,
  64         IPI_CALL_FUNC,
  65         IPI_CPU_STOP,
  66         IPI_IRQ_WORK,
  67         IPI_COMPLETION,
  68         NR_IPI,
  69         /*
  70          * CPU_BACKTRACE is special and not included in NR_IPI
  71          * or tracable with trace_ipi_*
  72          */
  73         IPI_CPU_BACKTRACE = NR_IPI,
  74         /*
  75          * SGI8-15 can be reserved by secure firmware, and thus may
  76          * not be usable by the kernel. Please keep the above limited
  77          * to at most 8 entries.
  78          */
  79         MAX_IPI
  80 };
  81
  82 static int ipi_irq_base __read_mostly;
  83 static int nr_ipi __read_mostly = NR_IPI;
  84 static struct irq_desc *ipi_desc[MAX_IPI] __read_mostly;
  85
  86 static void ipi_setup(int cpu);
  87
  88 static DECLARE_COMPLETION(cpu_running);
  89
  90 static struct smp_operations smp_ops __ro_after_init;
  91
  92 void __init smp_set_ops(const struct smp_operations *ops)
  93 {
  94         if (ops)
  95                 smp_ops = *ops;
  96 };
  97
  98 static unsigned long get_arch_pgd(pgd_t *pgd)
  99 {
 100 #ifdef CONFIG_ARM_LPAE
 101         return __phys_to_pfn(virt_to_phys(pgd));
 102 #else
 103         return virt_to_phys(pgd);
 104 #endif
 105 }
 106
 107 #if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
 108 static int secondary_biglittle_prepare(unsigned int cpu)
 109 {
 110         if (!cpu_vtable[cpu])
 111                 cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL);
 112
 113         return cpu_vtable[cpu] ? 0 : -ENOMEM;
 114 }
 115
 116 static void secondary_biglittle_init(void)
 117 {
 118         init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
 119 }
 120 #else
 121 static int secondary_biglittle_prepare(unsigned int cpu)
 122 {
 123         return 0;
 124 }
 125
 126 static void secondary_biglittle_init(void)
 127 {
 128 }
 129 #endif
 130
 131 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 132 {
 133         int ret;
 134
 135         if (!smp_ops.smp_boot_secondary)
 136                 return -ENOSYS;
 137
 138         ret = secondary_biglittle_prepare(cpu);
 139         if (ret)
 140                 return ret;
 141
 142         /*
 143          * We need to tell the secondary core where to find
 144          * its stack and the page tables.
 145          */
 146         secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
 147 #ifdef CONFIG_ARM_MPU
 148         secondary_data.mpu_rgn_info = &mpu_rgn_info;
 149 #endif
 150
 151 #ifdef CONFIG_MMU
 152         secondary_data.pgdir = virt_to_phys(idmap_pgd);
 153         secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
 154 #endif
 155         secondary_data.task = idle;
 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 after the
 292  * shutdown completed.
 293  */
 294 void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
 295 {
 296         pr_debug("CPU%u: shutdown\n", cpu);
 297
 298         clear_tasks_mm_cpumask(cpu);
 299         /*
 300          * platform_cpu_kill() is generally expected to do the powering off
 301          * and/or cutting of clocks to the dying CPU.  Optionally, this may
 302          * be done by the CPU which is dying in preference to supporting
 303          * this call, but that means there is _no_ synchronisation between
 304          * the requesting CPU and the dying CPU actually losing power.
 305          */
 306         if (!platform_cpu_kill(cpu))
 307                 pr_err("CPU%u: unable to kill\n", cpu);
 308 }
 309
 310 /*
 311  * Called from the idle thread for the CPU which has been shutdown.
 312  *
 313  * Note that we disable IRQs here, but do not re-enable them
 314  * before returning to the caller. This is also the behaviour
 315  * of the other hotplug-cpu capable cores, so presumably coming
 316  * out of idle fixes this.
 317  */
 318 void __noreturn arch_cpu_idle_dead(void)
 319 {
 320         unsigned int cpu = smp_processor_id();
 321
 322         idle_task_exit();
 323
 324         local_irq_disable();
 325
 326         /*
 327          * Flush the data out of the L1 cache for this CPU.  This must be
 328          * before the completion to ensure that data is safely written out
 329          * before platform_cpu_kill() gets called - which may disable
 330          * *this* CPU and power down its cache.
 331          */
 332         flush_cache_louis();
 333
 334         /*
 335          * Tell cpuhp_bp_sync_dead() that this CPU is now safe to dispose
 336          * of. Once this returns, power and/or clocks can be removed at
 337          * any point from this CPU and its cache by platform_cpu_kill().
 338          */
 339         cpuhp_ap_report_dead();
 340
 341         /*
 342          * Ensure that the cache lines associated with that completion are
 343          * written out.  This covers the case where _this_ CPU is doing the
 344          * powering down, to ensure that the completion is visible to the
 345          * CPU waiting for this one.
 346          */
 347         flush_cache_louis();
 348
 349         /*
 350          * The actual CPU shutdown procedure is at least platform (if not
 351          * CPU) specific.  This may remove power, or it may simply spin.
 352          *
 353          * Platforms are generally expected *NOT* to return from this call,
 354          * although there are some which do because they have no way to
 355          * power down the CPU.  These platforms are the _only_ reason we
 356          * have a return path which uses the fragment of assembly below.
 357          *
 358          * The return path should not be used for platforms which can
 359          * power off the CPU.
 360          */
 361         if (smp_ops.cpu_die)
 362                 smp_ops.cpu_die(cpu);
 363
 364         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 365                 cpu);
 366
 367         /*
 368          * Do not return to the idle loop - jump back to the secondary
 369          * cpu initialisation.  There's some initialisation which needs
 370          * to be repeated to undo the effects of taking the CPU offline.
 371          */
 372         __asm__("mov    sp, %0\n"
 373         "       mov     fp, #0\n"
 374         "       mov     r0, %1\n"
 375         "       b       secondary_start_kernel"
 376                 :
 377                 : "r" (task_stack_page(current) + THREAD_SIZE - 8),
 378                   "r" (current)
 379                 : "r0");
 380
 381         unreachable();
 382 }
 383 #endif /* CONFIG_HOTPLUG_CPU */
 384
 385 /*
 386  * Called by both boot and secondaries to move global data into
 387  * per-processor storage.
 388  */
 389 static void smp_store_cpu_info(unsigned int cpuid)
 390 {
 391         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 392
 393         cpu_info->loops_per_jiffy = loops_per_jiffy;
 394         cpu_info->cpuid = read_cpuid_id();
 395
 396         store_cpu_topology(cpuid);
 397         check_cpu_icache_size(cpuid);
 398 }
 399
 400 static void set_current(struct task_struct *cur)
 401 {
 402         /* Set TPIDRURO */
 403         asm("mcr p15, 0, %0, c13, c0, 3" :: "r"(cur) : "memory");
 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         local_fiq_disable();
 601
 602         if (system_state <= SYSTEM_RUNNING) {
 603                 raw_spin_lock(&stop_lock);
 604                 pr_crit("CPU%u: stopping\n", cpu);
 605                 dump_stack();
 606                 raw_spin_unlock(&stop_lock);
 607         }
 608
 609         set_cpu_online(cpu, false);
 610
 611         while (1) {
 612                 cpu_relax();
 613                 wfe();
 614         }
 615 }
 616
 617 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 618
 619 int register_ipi_completion(struct completion *completion, int cpu)
 620 {
 621         per_cpu(cpu_completion, cpu) = completion;
 622         return IPI_COMPLETION;
 623 }
 624
 625 static void ipi_complete(unsigned int cpu)
 626 {
 627         complete(per_cpu(cpu_completion, cpu));
 628 }
 629
 630 /*
 631  * Main handler for inter-processor interrupts
 632  */
 633 static void do_handle_IPI(int ipinr)
 634 {
 635         unsigned int cpu = smp_processor_id();
 636
 637         if ((unsigned)ipinr < NR_IPI)
 638                 trace_ipi_entry(ipi_types[ipinr]);
 639
 640         switch (ipinr) {
 641         case IPI_WAKEUP:
 642                 break;
 643
 644 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 645         case IPI_TIMER:
 646                 tick_receive_broadcast();
 647                 break;
 648 #endif
 649
 650         case IPI_RESCHEDULE:
 651                 scheduler_ipi();
 652                 break;
 653
 654         case IPI_CALL_FUNC:
 655                 generic_smp_call_function_interrupt();
 656                 break;
 657
 658         case IPI_CPU_STOP:
 659                 ipi_cpu_stop(cpu);
 660                 break;
 661
 662 #ifdef CONFIG_IRQ_WORK
 663         case IPI_IRQ_WORK:
 664                 irq_work_run();
 665                 break;
 666 #endif
 667
 668         case IPI_COMPLETION:
 669                 ipi_complete(cpu);
 670                 break;
 671
 672         case IPI_CPU_BACKTRACE:
 673                 printk_deferred_enter();
 674                 nmi_cpu_backtrace(get_irq_regs());
 675                 printk_deferred_exit();
 676                 break;
 677
 678         default:
 679                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 680                         cpu, ipinr);
 681                 break;
 682         }
 683
 684         if ((unsigned)ipinr < NR_IPI)
 685                 trace_ipi_exit(ipi_types[ipinr]);
 686 }
 687
 688 /* Legacy version, should go away once all irqchips have been converted */
 689 void handle_IPI(int ipinr, struct pt_regs *regs)
 690 {
 691         struct pt_regs *old_regs = set_irq_regs(regs);
 692
 693         irq_enter();
 694         do_handle_IPI(ipinr);
 695         irq_exit();
 696
 697         set_irq_regs(old_regs);
 698 }
 699
 700 static irqreturn_t ipi_handler(int irq, void *data)
 701 {
 702         do_handle_IPI(irq - ipi_irq_base);
 703         return IRQ_HANDLED;
 704 }
 705
 706 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 707 {
 708         trace_ipi_raise(target, ipi_types[ipinr]);
 709         __ipi_send_mask(ipi_desc[ipinr], target);
 710 }
 711
 712 static void ipi_setup(int cpu)
 713 {
 714         int i;
 715
 716         if (WARN_ON_ONCE(!ipi_irq_base))
 717                 return;
 718
 719         for (i = 0; i < nr_ipi; i++)
 720                 enable_percpu_irq(ipi_irq_base + i, 0);
 721 }
 722
 723 void __init set_smp_ipi_range(int ipi_base, int n)
 724 {
 725         int i;
 726
 727         WARN_ON(n < MAX_IPI);
 728         nr_ipi = min(n, MAX_IPI);
 729
 730         for (i = 0; i < nr_ipi; i++) {
 731                 int err;
 732
 733                 err = request_percpu_irq(ipi_base + i, ipi_handler,
 734                                          "IPI", &irq_stat);
 735                 WARN_ON(err);
 736
 737                 ipi_desc[i] = irq_to_desc(ipi_base + i);
 738                 irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
 739         }
 740
 741         ipi_irq_base = ipi_base;
 742
 743         /* Setup the boot CPU immediately */
 744         ipi_setup(smp_processor_id());
 745 }
 746
 747 void arch_smp_send_reschedule(int cpu)
 748 {
 749         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 750 }
 751
 752 void smp_send_stop(void)
 753 {
 754         unsigned long timeout;
 755         struct cpumask mask;
 756
 757         cpumask_copy(&mask, cpu_online_mask);
 758         cpumask_clear_cpu(smp_processor_id(), &mask);
 759         if (!cpumask_empty(&mask))
 760                 smp_cross_call(&mask, IPI_CPU_STOP);
 761
 762         /* Wait up to one second for other CPUs to stop */
 763         timeout = USEC_PER_SEC;
 764         while (num_online_cpus() > 1 && timeout--)
 765                 udelay(1);
 766
 767         if (num_online_cpus() > 1)
 768                 pr_warn("SMP: failed to stop secondary CPUs\n");
 769 }
 770
 771 /* In case panic() and panic() called at the same time on CPU1 and CPU2,
 772  * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
 773  * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
 774  * kdump fails. So split out the panic_smp_self_stop() and add
 775  * set_cpu_online(smp_processor_id(), false).
 776  */
 777 void __noreturn panic_smp_self_stop(void)
 778 {
 779         pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
 780                  smp_processor_id());
 781         set_cpu_online(smp_processor_id(), false);
 782         while (1)
 783                 cpu_relax();
 784 }
 785
 786 #ifdef CONFIG_CPU_FREQ
 787
 788 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 789 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 790 static unsigned long global_l_p_j_ref;
 791 static unsigned long global_l_p_j_ref_freq;
 792
 793 static int cpufreq_callback(struct notifier_block *nb,
 794                                         unsigned long val, void *data)
 795 {
 796         struct cpufreq_freqs *freq = data;
 797         struct cpumask *cpus = freq->policy->cpus;
 798         int cpu, first = cpumask_first(cpus);
 799         unsigned int lpj;
 800
 801         if (freq->flags & CPUFREQ_CONST_LOOPS)
 802                 return NOTIFY_OK;
 803
 804         if (!per_cpu(l_p_j_ref, first)) {
 805                 for_each_cpu(cpu, cpus) {
 806                         per_cpu(l_p_j_ref, cpu) =
 807                                 per_cpu(cpu_data, cpu).loops_per_jiffy;
 808                         per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 809                 }
 810
 811                 if (!global_l_p_j_ref) {
 812                         global_l_p_j_ref = loops_per_jiffy;
 813                         global_l_p_j_ref_freq = freq->old;
 814                 }
 815         }
 816
 817         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 818             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 819                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 820                                                 global_l_p_j_ref_freq,
 821                                                 freq->new);
 822
 823                 lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
 824                                     per_cpu(l_p_j_ref_freq, first), freq->new);
 825                 for_each_cpu(cpu, cpus)
 826                         per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
 827         }
 828         return NOTIFY_OK;
 829 }
 830
 831 static struct notifier_block cpufreq_notifier = {
 832         .notifier_call  = cpufreq_callback,
 833 };
 834
 835 static int __init register_cpufreq_notifier(void)
 836 {
 837         return cpufreq_register_notifier(&cpufreq_notifier,
 838                                                 CPUFREQ_TRANSITION_NOTIFIER);
 839 }
 840 core_initcall(register_cpufreq_notifier);
 841
 842 #endif
 843
 844 static void raise_nmi(cpumask_t *mask)
 845 {
 846         __ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask);
 847 }
 848
 849 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
 850 {
 851         nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_nmi);
 852 }