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