arch/arm/kernel/smp.c

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This source file includes following definitions.
smp_set_ops
get_arch_pgd
secondary_biglittle_prepare
secondary_biglittle_init
secondary_biglittle_prepare
secondary_biglittle_init
__cpu_up
smp_init_cpus
platform_can_secondary_boot
platform_can_cpu_hotplug
platform_cpu_kill
platform_cpu_disable
platform_can_hotplug_cpu
__cpu_disable
__cpu_die
arch_cpu_idle_dead
smp_store_cpu_info
secondary_start_kernel
smp_cpus_done
smp_prepare_boot_cpu
smp_prepare_cpus
set_smp_cross_call
smp_cross_call
show_ipi_list
smp_irq_stat_cpu
arch_send_call_function_ipi_mask
arch_send_wakeup_ipi_mask
arch_send_call_function_single_ipi
arch_irq_work_raise
tick_broadcast
ipi_cpu_stop
register_ipi_completion
ipi_complete
do_IPI
handle_IPI
smp_send_reschedule
smp_send_stop
panic_smp_self_stop
setup_profiling_timer
cpufreq_callback
register_cpufreq_notifier
raise_nmi
arch_trigger_cpumask_backtrace
   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 
  30 #include <linux/atomic.h>
  31 #include <asm/bugs.h>
  32 #include <asm/smp.h>
  33 #include <asm/cacheflush.h>
  34 #include <asm/cpu.h>
  35 #include <asm/cputype.h>
  36 #include <asm/exception.h>
  37 #include <asm/idmap.h>
  38 #include <asm/topology.h>
  39 #include <asm/mmu_context.h>
  40 #include <asm/pgtable.h>
  41 #include <asm/pgalloc.h>
  42 #include <asm/procinfo.h>
  43 #include <asm/processor.h>
  44 #include <asm/sections.h>
  45 #include <asm/tlbflush.h>
  46 #include <asm/ptrace.h>
  47 #include <asm/smp_plat.h>
  48 #include <asm/virt.h>
  49 #include <asm/mach/arch.h>
  50 #include <asm/mpu.h>
  51 
  52 #define CREATE_TRACE_POINTS
  53 #include <trace/events/ipi.h>
  54 
  55 /*
  56  * as from 2.5, kernels no longer have an init_tasks structure
  57  * so we need some other way of telling a new secondary core
  58  * where to place its SVC stack
  59  */
  60 struct secondary_data secondary_data;
  61 
  62 enum ipi_msg_type {
  63         IPI_WAKEUP,
  64         IPI_TIMER,
  65         IPI_RESCHEDULE,
  66         IPI_CALL_FUNC,
  67         IPI_CPU_STOP,
  68         IPI_IRQ_WORK,
  69         IPI_COMPLETION,
  70         /*
  71          * CPU_BACKTRACE is special and not included in NR_IPI
  72          * or tracable with trace_ipi_*
  73          */
  74         IPI_CPU_BACKTRACE,
  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 };
  81 
  82 static DECLARE_COMPLETION(cpu_running);
  83 
  84 static struct smp_operations smp_ops __ro_after_init;
  85 
  86 void __init smp_set_ops(const struct smp_operations *ops)
  87 {
  88         if (ops)
  89                 smp_ops = *ops;
  90 };
  91 
  92 static unsigned long get_arch_pgd(pgd_t *pgd)
  93 {
  94 #ifdef CONFIG_ARM_LPAE
  95         return __phys_to_pfn(virt_to_phys(pgd));
  96 #else
  97         return virt_to_phys(pgd);
  98 #endif
  99 }
 100 
 101 #if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
 102 static int secondary_biglittle_prepare(unsigned int cpu)
 103 {
 104         if (!cpu_vtable[cpu])
 105                 cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL);
 106 
 107         return cpu_vtable[cpu] ? 0 : -ENOMEM;
 108 }
 109 
 110 static void secondary_biglittle_init(void)
 111 {
 112         init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
 113 }
 114 #else
 115 static int secondary_biglittle_prepare(unsigned int cpu)
 116 {
 117         return 0;
 118 }
 119 
 120 static void secondary_biglittle_init(void)
 121 {
 122 }
 123 #endif
 124 
 125 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 126 {
 127         int ret;
 128 
 129         if (!smp_ops.smp_boot_secondary)
 130                 return -ENOSYS;
 131 
 132         ret = secondary_biglittle_prepare(cpu);
 133         if (ret)
 134                 return ret;
 135 
 136         /*
 137          * We need to tell the secondary core where to find
 138          * its stack and the page tables.
 139          */
 140         secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
 141 #ifdef CONFIG_ARM_MPU
 142         secondary_data.mpu_rgn_info = &mpu_rgn_info;
 143 #endif
 144 
 145 #ifdef CONFIG_MMU
 146         secondary_data.pgdir = virt_to_phys(idmap_pgd);
 147         secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
 148 #endif
 149         sync_cache_w(&secondary_data);
 150 
 151         /*
 152          * Now bring the CPU into our world.
 153          */
 154         ret = smp_ops.smp_boot_secondary(cpu, idle);
 155         if (ret == 0) {
 156                 /*
 157                  * CPU was successfully started, wait for it
 158                  * to come online or time out.
 159                  */
 160                 wait_for_completion_timeout(&cpu_running,
 161                                                  msecs_to_jiffies(1000));
 162 
 163                 if (!cpu_online(cpu)) {
 164                         pr_crit("CPU%u: failed to come online\n", cpu);
 165                         ret = -EIO;
 166                 }
 167         } else {
 168                 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
 169         }
 170 
 171 
 172         memset(&secondary_data, 0, sizeof(secondary_data));
 173         return ret;
 174 }
 175 
 176 /* platform specific SMP operations */
 177 void __init smp_init_cpus(void)
 178 {
 179         if (smp_ops.smp_init_cpus)
 180                 smp_ops.smp_init_cpus();
 181 }
 182 
 183 int platform_can_secondary_boot(void)
 184 {
 185         return !!smp_ops.smp_boot_secondary;
 186 }
 187 
 188 int platform_can_cpu_hotplug(void)
 189 {
 190 #ifdef CONFIG_HOTPLUG_CPU
 191         if (smp_ops.cpu_kill)
 192                 return 1;
 193 #endif
 194 
 195         return 0;
 196 }
 197 
 198 #ifdef CONFIG_HOTPLUG_CPU
 199 static int platform_cpu_kill(unsigned int cpu)
 200 {
 201         if (smp_ops.cpu_kill)
 202                 return smp_ops.cpu_kill(cpu);
 203         return 1;
 204 }
 205 
 206 static int platform_cpu_disable(unsigned int cpu)
 207 {
 208         if (smp_ops.cpu_disable)
 209                 return smp_ops.cpu_disable(cpu);
 210 
 211         return 0;
 212 }
 213 
 214 int platform_can_hotplug_cpu(unsigned int cpu)
 215 {
 216         /* cpu_die must be specified to support hotplug */
 217         if (!smp_ops.cpu_die)
 218                 return 0;
 219 
 220         if (smp_ops.cpu_can_disable)
 221                 return smp_ops.cpu_can_disable(cpu);
 222 
 223         /*
 224          * By default, allow disabling all CPUs except the first one,
 225          * since this is special on a lot of platforms, e.g. because
 226          * of clock tick interrupts.
 227          */
 228         return cpu != 0;
 229 }
 230 
 231 /*
 232  * __cpu_disable runs on the processor to be shutdown.
 233  */
 234 int __cpu_disable(void)
 235 {
 236         unsigned int cpu = smp_processor_id();
 237         int ret;
 238 
 239         ret = platform_cpu_disable(cpu);
 240         if (ret)
 241                 return ret;
 242 
 243 #ifdef CONFIG_GENERIC_ARCH_TOPOLOGY
 244         remove_cpu_topology(cpu);
 245 #endif
 246 
 247         /*
 248          * Take this CPU offline.  Once we clear this, we can't return,
 249          * and we must not schedule until we're ready to give up the cpu.
 250          */
 251         set_cpu_online(cpu, false);
 252 
 253         /*
 254          * OK - migrate IRQs away from this CPU
 255          */
 256         irq_migrate_all_off_this_cpu();
 257 
 258         /*
 259          * Flush user cache and TLB mappings, and then remove this CPU
 260          * from the vm mask set of all processes.
 261          *
 262          * Caches are flushed to the Level of Unification Inner Shareable
 263          * to write-back dirty lines to unified caches shared by all CPUs.
 264          */
 265         flush_cache_louis();
 266         local_flush_tlb_all();
 267 
 268         return 0;
 269 }
 270 
 271 /*
 272  * called on the thread which is asking for a CPU to be shutdown -
 273  * waits until shutdown has completed, or it is timed out.
 274  */
 275 void __cpu_die(unsigned int cpu)
 276 {
 277         if (!cpu_wait_death(cpu, 5)) {
 278                 pr_err("CPU%u: cpu didn't die\n", cpu);
 279                 return;
 280         }
 281         pr_debug("CPU%u: shutdown\n", cpu);
 282 
 283         clear_tasks_mm_cpumask(cpu);
 284         /*
 285          * platform_cpu_kill() is generally expected to do the powering off
 286          * and/or cutting of clocks to the dying CPU.  Optionally, this may
 287          * be done by the CPU which is dying in preference to supporting
 288          * this call, but that means there is _no_ synchronisation between
 289          * the requesting CPU and the dying CPU actually losing power.
 290          */
 291         if (!platform_cpu_kill(cpu))
 292                 pr_err("CPU%u: unable to kill\n", cpu);
 293 }
 294 
 295 /*
 296  * Called from the idle thread for the CPU which has been shutdown.
 297  *
 298  * Note that we disable IRQs here, but do not re-enable them
 299  * before returning to the caller. This is also the behaviour
 300  * of the other hotplug-cpu capable cores, so presumably coming
 301  * out of idle fixes this.
 302  */
 303 void arch_cpu_idle_dead(void)
 304 {
 305         unsigned int cpu = smp_processor_id();
 306 
 307         idle_task_exit();
 308 
 309         local_irq_disable();
 310 
 311         /*
 312          * Flush the data out of the L1 cache for this CPU.  This must be
 313          * before the completion to ensure that data is safely written out
 314          * before platform_cpu_kill() gets called - which may disable
 315          * *this* CPU and power down its cache.
 316          */
 317         flush_cache_louis();
 318 
 319         /*
 320          * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
 321          * this returns, power and/or clocks can be removed at any point
 322          * from this CPU and its cache by platform_cpu_kill().
 323          */
 324         (void)cpu_report_death();
 325 
 326         /*
 327          * Ensure that the cache lines associated with that completion are
 328          * written out.  This covers the case where _this_ CPU is doing the
 329          * powering down, to ensure that the completion is visible to the
 330          * CPU waiting for this one.
 331          */
 332         flush_cache_louis();
 333 
 334         /*
 335          * The actual CPU shutdown procedure is at least platform (if not
 336          * CPU) specific.  This may remove power, or it may simply spin.
 337          *
 338          * Platforms are generally expected *NOT* to return from this call,
 339          * although there are some which do because they have no way to
 340          * power down the CPU.  These platforms are the _only_ reason we
 341          * have a return path which uses the fragment of assembly below.
 342          *
 343          * The return path should not be used for platforms which can
 344          * power off the CPU.
 345          */
 346         if (smp_ops.cpu_die)
 347                 smp_ops.cpu_die(cpu);
 348 
 349         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 350                 cpu);
 351 
 352         /*
 353          * Do not return to the idle loop - jump back to the secondary
 354          * cpu initialisation.  There's some initialisation which needs
 355          * to be repeated to undo the effects of taking the CPU offline.
 356          */
 357         __asm__("mov    sp, %0\n"
 358         "       mov     fp, #0\n"
 359         "       b       secondary_start_kernel"
 360                 :
 361                 : "r" (task_stack_page(current) + THREAD_SIZE - 8));
 362 }
 363 #endif /* CONFIG_HOTPLUG_CPU */
 364 
 365 /*
 366  * Called by both boot and secondaries to move global data into
 367  * per-processor storage.
 368  */
 369 static void smp_store_cpu_info(unsigned int cpuid)
 370 {
 371         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 372 
 373         cpu_info->loops_per_jiffy = loops_per_jiffy;
 374         cpu_info->cpuid = read_cpuid_id();
 375 
 376         store_cpu_topology(cpuid);
 377         check_cpu_icache_size(cpuid);
 378 }
 379 
 380 /*
 381  * This is the secondary CPU boot entry.  We're using this CPUs
 382  * idle thread stack, but a set of temporary page tables.
 383  */
 384 asmlinkage void secondary_start_kernel(void)
 385 {
 386         struct mm_struct *mm = &init_mm;
 387         unsigned int cpu;
 388 
 389         secondary_biglittle_init();
 390 
 391         /*
 392          * The identity mapping is uncached (strongly ordered), so
 393          * switch away from it before attempting any exclusive accesses.
 394          */
 395         cpu_switch_mm(mm->pgd, mm);
 396         local_flush_bp_all();
 397         enter_lazy_tlb(mm, current);
 398         local_flush_tlb_all();
 399 
 400         /*
 401          * All kernel threads share the same mm context; grab a
 402          * reference and switch to it.
 403          */
 404         cpu = smp_processor_id();
 405         mmgrab(mm);
 406         current->active_mm = mm;
 407         cpumask_set_cpu(cpu, mm_cpumask(mm));
 408 
 409         cpu_init();
 410 
 411 #ifndef CONFIG_MMU
 412         setup_vectors_base();
 413 #endif
 414         pr_debug("CPU%u: Booted secondary processor\n", cpu);
 415 
 416         preempt_disable();
 417         trace_hardirqs_off();
 418 
 419         /*
 420          * Give the platform a chance to do its own initialisation.
 421          */
 422         if (smp_ops.smp_secondary_init)
 423                 smp_ops.smp_secondary_init(cpu);
 424 
 425         notify_cpu_starting(cpu);
 426 
 427         calibrate_delay();
 428 
 429         smp_store_cpu_info(cpu);
 430 
 431         /*
 432          * OK, now it's safe to let the boot CPU continue.  Wait for
 433          * the CPU migration code to notice that the CPU is online
 434          * before we continue - which happens after __cpu_up returns.
 435          */
 436         set_cpu_online(cpu, true);
 437 
 438         check_other_bugs();
 439 
 440         complete(&cpu_running);
 441 
 442         local_irq_enable();
 443         local_fiq_enable();
 444         local_abt_enable();
 445 
 446         /*
 447          * OK, it's off to the idle thread for us
 448          */
 449         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 450 }
 451 
 452 void __init smp_cpus_done(unsigned int max_cpus)
 453 {
 454         int cpu;
 455         unsigned long bogosum = 0;
 456 
 457         for_each_online_cpu(cpu)
 458                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 459 
 460         printk(KERN_INFO "SMP: Total of %d processors activated "
 461                "(%lu.%02lu BogoMIPS).\n",
 462                num_online_cpus(),
 463                bogosum / (500000/HZ),
 464                (bogosum / (5000/HZ)) % 100);
 465 
 466         hyp_mode_check();
 467 }
 468 
 469 void __init smp_prepare_boot_cpu(void)
 470 {
 471         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 472 }
 473 
 474 void __init smp_prepare_cpus(unsigned int max_cpus)
 475 {
 476         unsigned int ncores = num_possible_cpus();
 477 
 478         init_cpu_topology();
 479 
 480         smp_store_cpu_info(smp_processor_id());
 481 
 482         /*
 483          * are we trying to boot more cores than exist?
 484          */
 485         if (max_cpus > ncores)
 486                 max_cpus = ncores;
 487         if (ncores > 1 && max_cpus) {
 488                 /*
 489                  * Initialise the present map, which describes the set of CPUs
 490                  * actually populated at the present time. A platform should
 491                  * re-initialize the map in the platforms smp_prepare_cpus()
 492                  * if present != possible (e.g. physical hotplug).
 493                  */
 494                 init_cpu_present(cpu_possible_mask);
 495 
 496                 /*
 497                  * Initialise the SCU if there are more than one CPU
 498                  * and let them know where to start.
 499                  */
 500                 if (smp_ops.smp_prepare_cpus)
 501                         smp_ops.smp_prepare_cpus(max_cpus);
 502         }
 503 }
 504 
 505 static void (*__smp_cross_call)(const struct cpumask *, unsigned int);
 506 
 507 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
 508 {
 509         if (!__smp_cross_call)
 510                 __smp_cross_call = fn;
 511 }
 512 
 513 static const char *ipi_types[NR_IPI] __tracepoint_string = {
 514 #define S(x,s)  [x] = s
 515         S(IPI_WAKEUP, "CPU wakeup interrupts"),
 516         S(IPI_TIMER, "Timer broadcast interrupts"),
 517         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
 518         S(IPI_CALL_FUNC, "Function call interrupts"),
 519         S(IPI_CPU_STOP, "CPU stop interrupts"),
 520         S(IPI_IRQ_WORK, "IRQ work interrupts"),
 521         S(IPI_COMPLETION, "completion interrupts"),
 522 };
 523 
 524 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 525 {
 526         trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
 527         __smp_cross_call(target, ipinr);
 528 }
 529 
 530 void show_ipi_list(struct seq_file *p, int prec)
 531 {
 532         unsigned int cpu, i;
 533 
 534         for (i = 0; i < NR_IPI; i++) {
 535                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 536 
 537                 for_each_online_cpu(cpu)
 538                         seq_printf(p, "%10u ",
 539                                    __get_irq_stat(cpu, ipi_irqs[i]));
 540 
 541                 seq_printf(p, " %s\n", ipi_types[i]);
 542         }
 543 }
 544 
 545 u64 smp_irq_stat_cpu(unsigned int cpu)
 546 {
 547         u64 sum = 0;
 548         int i;
 549 
 550         for (i = 0; i < NR_IPI; i++)
 551                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
 552 
 553         return sum;
 554 }
 555 
 556 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 557 {
 558         smp_cross_call(mask, IPI_CALL_FUNC);
 559 }
 560 
 561 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 562 {
 563         smp_cross_call(mask, IPI_WAKEUP);
 564 }
 565 
 566 void arch_send_call_function_single_ipi(int cpu)
 567 {
 568         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
 569 }
 570 
 571 #ifdef CONFIG_IRQ_WORK
 572 void arch_irq_work_raise(void)
 573 {
 574         if (arch_irq_work_has_interrupt())
 575                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 576 }
 577 #endif
 578 
 579 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 580 void tick_broadcast(const struct cpumask *mask)
 581 {
 582         smp_cross_call(mask, IPI_TIMER);
 583 }
 584 #endif
 585 
 586 static DEFINE_RAW_SPINLOCK(stop_lock);
 587 
 588 /*
 589  * ipi_cpu_stop - handle IPI from smp_send_stop()
 590  */
 591 static void ipi_cpu_stop(unsigned int cpu)
 592 {
 593         if (system_state <= SYSTEM_RUNNING) {
 594                 raw_spin_lock(&stop_lock);
 595                 pr_crit("CPU%u: stopping\n", cpu);
 596                 dump_stack();
 597                 raw_spin_unlock(&stop_lock);
 598         }
 599 
 600         set_cpu_online(cpu, false);
 601 
 602         local_fiq_disable();
 603         local_irq_disable();
 604 
 605         while (1) {
 606                 cpu_relax();
 607                 wfe();
 608         }
 609 }
 610 
 611 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 612 
 613 int register_ipi_completion(struct completion *completion, int cpu)
 614 {
 615         per_cpu(cpu_completion, cpu) = completion;
 616         return IPI_COMPLETION;
 617 }
 618 
 619 static void ipi_complete(unsigned int cpu)
 620 {
 621         complete(per_cpu(cpu_completion, cpu));
 622 }
 623 
 624 /*
 625  * Main handler for inter-processor interrupts
 626  */
 627 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 628 {
 629         handle_IPI(ipinr, regs);
 630 }
 631 
 632 void handle_IPI(int ipinr, struct pt_regs *regs)
 633 {
 634         unsigned int cpu = smp_processor_id();
 635         struct pt_regs *old_regs = set_irq_regs(regs);
 636 
 637         if ((unsigned)ipinr < NR_IPI) {
 638                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 639                 __inc_irq_stat(cpu, ipi_irqs[ipinr]);
 640         }
 641 
 642         switch (ipinr) {
 643         case IPI_WAKEUP:
 644                 break;
 645 
 646 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 647         case IPI_TIMER:
 648                 irq_enter();
 649                 tick_receive_broadcast();
 650                 irq_exit();
 651                 break;
 652 #endif
 653 
 654         case IPI_RESCHEDULE:
 655                 scheduler_ipi();
 656                 break;
 657 
 658         case IPI_CALL_FUNC:
 659                 irq_enter();
 660                 generic_smp_call_function_interrupt();
 661                 irq_exit();
 662                 break;
 663 
 664         case IPI_CPU_STOP:
 665                 irq_enter();
 666                 ipi_cpu_stop(cpu);
 667                 irq_exit();
 668                 break;
 669 
 670 #ifdef CONFIG_IRQ_WORK
 671         case IPI_IRQ_WORK:
 672                 irq_enter();
 673                 irq_work_run();
 674                 irq_exit();
 675                 break;
 676 #endif
 677 
 678         case IPI_COMPLETION:
 679                 irq_enter();
 680                 ipi_complete(cpu);
 681                 irq_exit();
 682                 break;
 683 
 684         case IPI_CPU_BACKTRACE:
 685                 printk_nmi_enter();
 686                 irq_enter();
 687                 nmi_cpu_backtrace(regs);
 688                 irq_exit();
 689                 printk_nmi_exit();
 690                 break;
 691 
 692         default:
 693                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 694                         cpu, ipinr);
 695                 break;
 696         }
 697 
 698         if ((unsigned)ipinr < NR_IPI)
 699                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 700         set_irq_regs(old_regs);
 701 }
 702 
 703 void smp_send_reschedule(int cpu)
 704 {
 705         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 706 }
 707 
 708 void smp_send_stop(void)
 709 {
 710         unsigned long timeout;
 711         struct cpumask mask;
 712 
 713         cpumask_copy(&mask, cpu_online_mask);
 714         cpumask_clear_cpu(smp_processor_id(), &mask);
 715         if (!cpumask_empty(&mask))
 716                 smp_cross_call(&mask, IPI_CPU_STOP);
 717 
 718         /* Wait up to one second for other CPUs to stop */
 719         timeout = USEC_PER_SEC;
 720         while (num_online_cpus() > 1 && timeout--)
 721                 udelay(1);
 722 
 723         if (num_online_cpus() > 1)
 724                 pr_warn("SMP: failed to stop secondary CPUs\n");
 725 }
 726 
 727 /* In case panic() and panic() called at the same time on CPU1 and CPU2,
 728  * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
 729  * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
 730  * kdump fails. So split out the panic_smp_self_stop() and add
 731  * set_cpu_online(smp_processor_id(), false).
 732  */
 733 void panic_smp_self_stop(void)
 734 {
 735         pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
 736                  smp_processor_id());
 737         set_cpu_online(smp_processor_id(), false);
 738         while (1)
 739                 cpu_relax();
 740 }
 741 
 742 /*
 743  * not supported here
 744  */
 745 int setup_profiling_timer(unsigned int multiplier)
 746 {
 747         return -EINVAL;
 748 }
 749 
 750 #ifdef CONFIG_CPU_FREQ
 751 
 752 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 753 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 754 static unsigned long global_l_p_j_ref;
 755 static unsigned long global_l_p_j_ref_freq;
 756 
 757 static int cpufreq_callback(struct notifier_block *nb,
 758                                         unsigned long val, void *data)
 759 {
 760         struct cpufreq_freqs *freq = data;
 761         struct cpumask *cpus = freq->policy->cpus;
 762         int cpu, first = cpumask_first(cpus);
 763         unsigned int lpj;
 764 
 765         if (freq->flags & CPUFREQ_CONST_LOOPS)
 766                 return NOTIFY_OK;
 767 
 768         if (!per_cpu(l_p_j_ref, first)) {
 769                 for_each_cpu(cpu, cpus) {
 770                         per_cpu(l_p_j_ref, cpu) =
 771                                 per_cpu(cpu_data, cpu).loops_per_jiffy;
 772                         per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 773                 }
 774 
 775                 if (!global_l_p_j_ref) {
 776                         global_l_p_j_ref = loops_per_jiffy;
 777                         global_l_p_j_ref_freq = freq->old;
 778                 }
 779         }
 780 
 781         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 782             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 783                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 784                                                 global_l_p_j_ref_freq,
 785                                                 freq->new);
 786 
 787                 lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
 788                                     per_cpu(l_p_j_ref_freq, first), freq->new);
 789                 for_each_cpu(cpu, cpus)
 790                         per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
 791         }
 792         return NOTIFY_OK;
 793 }
 794 
 795 static struct notifier_block cpufreq_notifier = {
 796         .notifier_call  = cpufreq_callback,
 797 };
 798 
 799 static int __init register_cpufreq_notifier(void)
 800 {
 801         return cpufreq_register_notifier(&cpufreq_notifier,
 802                                                 CPUFREQ_TRANSITION_NOTIFIER);
 803 }
 804 core_initcall(register_cpufreq_notifier);
 805 
 806 #endif
 807 
 808 static void raise_nmi(cpumask_t *mask)
 809 {
 810         __smp_cross_call(mask, IPI_CPU_BACKTRACE);
 811 }
 812 
 813 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 814 {
 815         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
 816 }
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root/arch/arm/kernel/smp.c

DEFINITIONS
