arch/x86/kernel/apic/nmi.c

   1 /*
   2  *  NMI watchdog support on APIC systems
   3  *
   4  *  Started by Ingo Molnar <mingo@redhat.com>
   5  *
   6  *  Fixes:
   7  *  Mikael Pettersson   : AMD K7 support for local APIC NMI watchdog.
   8  *  Mikael Pettersson   : Power Management for local APIC NMI watchdog.
   9  *  Mikael Pettersson   : Pentium 4 support for local APIC NMI watchdog.
  10  *  Pavel Machek and
  11  *  Mikael Pettersson   : PM converted to driver model. Disable/enable API.
  12  */
  13
  14 #include <asm/apic.h>
  15
  16 #include <linux/nmi.h>
  17 #include <linux/mm.h>
  18 #include <linux/delay.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/module.h>
  21 #include <linux/slab.h>
  22 #include <linux/sysdev.h>
  23 #include <linux/sysctl.h>
  24 #include <linux/percpu.h>
  25 #include <linux/kprobes.h>
  26 #include <linux/cpumask.h>
  27 #include <linux/kernel_stat.h>
  28 #include <linux/kdebug.h>
  29 #include <linux/smp.h>
  30
  31 #include <asm/i8259.h>
  32 #include <asm/io_apic.h>
  33 #include <asm/proto.h>
  34 #include <asm/timer.h>
  35
  36 #include <asm/mce.h>
  37
  38 #include <asm/mach_traps.h>
  39
  40 int unknown_nmi_panic;
  41 int nmi_watchdog_enabled;
  42
  43 /* For reliability, we're prepared to waste bits here. */
  44 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
  45
  46 /* nmi_active:
  47  * >0: the lapic NMI watchdog is active, but can be disabled
  48  * <0: the lapic NMI watchdog has not been set up, and cannot
  49  *     be enabled
  50  *  0: the lapic NMI watchdog is disabled, but can be enabled
  51  */
  52 atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
  53 EXPORT_SYMBOL(nmi_active);
  54
  55 unsigned int nmi_watchdog = NMI_NONE;
  56 EXPORT_SYMBOL(nmi_watchdog);
  57
  58 static int panic_on_timeout;
  59
  60 static unsigned int nmi_hz = HZ;
  61 static DEFINE_PER_CPU(short, wd_enabled);
  62 static int endflag __initdata;
  63
  64 static inline unsigned int get_nmi_count(int cpu)
  65 {
  66         return per_cpu(irq_stat, cpu).__nmi_count;
  67 }
  68
  69 static inline int mce_in_progress(void)
  70 {
  71 #if defined(CONFIG_X86_MCE)
  72         return atomic_read(&mce_entry) > 0;
  73 #endif
  74         return 0;
  75 }
  76
  77 /*
  78  * Take the local apic timer and PIT/HPET into account. We don't
  79  * know which one is active, when we have highres/dyntick on
  80  */
  81 static inline unsigned int get_timer_irqs(int cpu)
  82 {
  83         return per_cpu(irq_stat, cpu).apic_timer_irqs +
  84                 per_cpu(irq_stat, cpu).irq0_irqs;
  85 }
  86
  87 #ifdef CONFIG_SMP
  88 /*
  89  * The performance counters used by NMI_LOCAL_APIC don't trigger when
  90  * the CPU is idle. To make sure the NMI watchdog really ticks on all
  91  * CPUs during the test make them busy.
  92  */
  93 static __init void nmi_cpu_busy(void *data)
  94 {
  95         local_irq_enable_in_hardirq();
  96         /*
  97          * Intentionally don't use cpu_relax here. This is
  98          * to make sure that the performance counter really ticks,
  99          * even if there is a simulator or similar that catches the
 100          * pause instruction. On a real HT machine this is fine because
 101          * all other CPUs are busy with "useless" delay loops and don't
 102          * care if they get somewhat less cycles.
 103          */
 104         while (endflag == 0)
 105                 mb();
 106 }
 107 #endif
 108
 109 static void report_broken_nmi(int cpu, unsigned int *prev_nmi_count)
 110 {
 111         printk(KERN_CONT "\n");
 112
 113         printk(KERN_WARNING
 114                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
 115                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
 116
 117         printk(KERN_WARNING
 118                 "Please report this to bugzilla.kernel.org,\n");
 119         printk(KERN_WARNING
 120                 "and attach the output of the 'dmesg' command.\n");
 121
 122         per_cpu(wd_enabled, cpu) = 0;
 123         atomic_dec(&nmi_active);
 124 }
 125
 126 static void __acpi_nmi_disable(void *__unused)
 127 {
 128         apic_write(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED);
 129 }
 130
 131 int __init check_nmi_watchdog(void)
 132 {
 133         unsigned int *prev_nmi_count;
 134         int cpu;
 135
 136         if (!nmi_watchdog_active() || !atomic_read(&nmi_active))
 137                 return 0;
 138
 139         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
 140         if (!prev_nmi_count)
 141                 goto error;
 142
 143         printk(KERN_INFO "Testing NMI watchdog ... ");
 144
 145 #ifdef CONFIG_SMP
 146         if (nmi_watchdog == NMI_LOCAL_APIC)
 147                 smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
 148 #endif
 149
 150         for_each_possible_cpu(cpu)
 151                 prev_nmi_count[cpu] = get_nmi_count(cpu);
 152         local_irq_enable();
 153         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
 154
 155         for_each_online_cpu(cpu) {
 156                 if (!per_cpu(wd_enabled, cpu))
 157                         continue;
 158                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
 159                         report_broken_nmi(cpu, prev_nmi_count);
 160         }
 161         endflag = 1;
 162         if (!atomic_read(&nmi_active)) {
 163                 kfree(prev_nmi_count);
 164                 atomic_set(&nmi_active, -1);
 165                 goto error;
 166         }
 167         printk("OK.\n");
 168
 169         /*
 170          * now that we know it works we can reduce NMI frequency to
 171          * something more reasonable; makes a difference in some configs
 172          */
 173         if (nmi_watchdog == NMI_LOCAL_APIC)
 174                 nmi_hz = lapic_adjust_nmi_hz(1);
 175
 176         kfree(prev_nmi_count);
 177         return 0;
 178 error:
 179         if (nmi_watchdog == NMI_IO_APIC) {
 180                 if (!timer_through_8259)
 181                         legacy_pic->chip->mask(0);
 182                 on_each_cpu(__acpi_nmi_disable, NULL, 1);
 183         }
 184
 185 #ifdef CONFIG_X86_32
 186         timer_ack = 0;
 187 #endif
 188         return -1;
 189 }
 190
 191 static int __init setup_nmi_watchdog(char *str)
 192 {
 193         unsigned int nmi;
 194
 195         if (!strncmp(str, "panic", 5)) {
 196                 panic_on_timeout = 1;
 197                 str = strchr(str, ',');
 198                 if (!str)
 199                         return 1;
 200                 ++str;
 201         }
 202
 203         if (!strncmp(str, "lapic", 5))
 204                 nmi_watchdog = NMI_LOCAL_APIC;
 205         else if (!strncmp(str, "ioapic", 6))
 206                 nmi_watchdog = NMI_IO_APIC;
 207         else {
 208                 get_option(&str, &nmi);
 209                 if (nmi >= NMI_INVALID)
 210                         return 0;
 211                 nmi_watchdog = nmi;
 212         }
 213
 214         return 1;
 215 }
 216 __setup("nmi_watchdog=", setup_nmi_watchdog);
 217
 218 /*
 219  * Suspend/resume support
 220  */
 221 #ifdef CONFIG_PM
 222
 223 static int nmi_pm_active; /* nmi_active before suspend */
 224
 225 static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state)
 226 {
 227         /* only CPU0 goes here, other CPUs should be offline */
 228         nmi_pm_active = atomic_read(&nmi_active);
 229         stop_apic_nmi_watchdog(NULL);
 230         BUG_ON(atomic_read(&nmi_active) != 0);
 231         return 0;
 232 }
 233
 234 static int lapic_nmi_resume(struct sys_device *dev)
 235 {
 236         /* only CPU0 goes here, other CPUs should be offline */
 237         if (nmi_pm_active > 0) {
 238                 setup_apic_nmi_watchdog(NULL);
 239                 touch_nmi_watchdog();
 240         }
 241         return 0;
 242 }
 243
 244 static struct sysdev_class nmi_sysclass = {
 245         .name           = "lapic_nmi",
 246         .resume         = lapic_nmi_resume,
 247         .suspend        = lapic_nmi_suspend,
 248 };
 249
 250 static struct sys_device device_lapic_nmi = {
 251         .id     = 0,
 252         .cls    = &nmi_sysclass,
 253 };
 254
 255 static int __init init_lapic_nmi_sysfs(void)
 256 {
 257         int error;
 258
 259         /*
 260          * should really be a BUG_ON but b/c this is an
 261          * init call, it just doesn't work.  -dcz
 262          */
 263         if (nmi_watchdog != NMI_LOCAL_APIC)
 264                 return 0;
 265
 266         if (atomic_read(&nmi_active) < 0)
 267                 return 0;
 268
 269         error = sysdev_class_register(&nmi_sysclass);
 270         if (!error)
 271                 error = sysdev_register(&device_lapic_nmi);
 272         return error;
 273 }
 274
 275 /* must come after the local APIC's device_initcall() */
 276 late_initcall(init_lapic_nmi_sysfs);
 277
 278 #endif  /* CONFIG_PM */
 279
 280 static void __acpi_nmi_enable(void *__unused)
 281 {
 282         apic_write(APIC_LVT0, APIC_DM_NMI);
 283 }
 284
 285 /*
 286  * Enable timer based NMIs on all CPUs:
 287  */
 288 void acpi_nmi_enable(void)
 289 {
 290         if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
 291                 on_each_cpu(__acpi_nmi_enable, NULL, 1);
 292 }
 293
 294 /*
 295  * Disable timer based NMIs on all CPUs:
 296  */
 297 void acpi_nmi_disable(void)
 298 {
 299         if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
 300                 on_each_cpu(__acpi_nmi_disable, NULL, 1);
 301 }
 302
 303 /*
 304  * This function is called as soon the LAPIC NMI watchdog driver has everything
 305  * in place and it's ready to check if the NMIs belong to the NMI watchdog
 306  */
 307 void cpu_nmi_set_wd_enabled(void)
 308 {
 309         __get_cpu_var(wd_enabled) = 1;
 310 }
 311
 312 void setup_apic_nmi_watchdog(void *unused)
 313 {
 314         if (__get_cpu_var(wd_enabled))
 315                 return;
 316
 317         /* cheap hack to support suspend/resume */
 318         /* if cpu0 is not active neither should the other cpus */
 319         if (smp_processor_id() != 0 && atomic_read(&nmi_active) <= 0)
 320                 return;
 321
 322         switch (nmi_watchdog) {
 323         case NMI_LOCAL_APIC:
 324                 if (lapic_watchdog_init(nmi_hz) < 0) {
 325                         __get_cpu_var(wd_enabled) = 0;
 326                         return;
 327                 }
 328                 /* FALL THROUGH */
 329         case NMI_IO_APIC:
 330                 __get_cpu_var(wd_enabled) = 1;
 331                 atomic_inc(&nmi_active);
 332         }
 333 }
 334
 335 void stop_apic_nmi_watchdog(void *unused)
 336 {
 337         /* only support LOCAL and IO APICs for now */
 338         if (!nmi_watchdog_active())
 339                 return;
 340         if (__get_cpu_var(wd_enabled) == 0)
 341                 return;
 342         if (nmi_watchdog == NMI_LOCAL_APIC)
 343                 lapic_watchdog_stop();
 344         else
 345                 __acpi_nmi_disable(NULL);
 346         __get_cpu_var(wd_enabled) = 0;
 347         atomic_dec(&nmi_active);
 348 }
 349
 350 /*
 351  * the best way to detect whether a CPU has a 'hard lockup' problem
 352  * is to check it's local APIC timer IRQ counts. If they are not
 353  * changing then that CPU has some problem.
 354  *
 355  * as these watchdog NMI IRQs are generated on every CPU, we only
 356  * have to check the current processor.
 357  *
 358  * since NMIs don't listen to _any_ locks, we have to be extremely
 359  * careful not to rely on unsafe variables. The printk might lock
 360  * up though, so we have to break up any console locks first ...
 361  * [when there will be more tty-related locks, break them up here too!]
 362  */
 363
 364 static DEFINE_PER_CPU(unsigned, last_irq_sum);
 365 static DEFINE_PER_CPU(long, alert_counter);
 366 static DEFINE_PER_CPU(int, nmi_touch);
 367
 368 void touch_nmi_watchdog(void)
 369 {
 370         if (nmi_watchdog_active()) {
 371                 unsigned cpu;
 372
 373                 /*
 374                  * Tell other CPUs to reset their alert counters. We cannot
 375                  * do it ourselves because the alert count increase is not
 376                  * atomic.
 377                  */
 378                 for_each_present_cpu(cpu) {
 379                         if (per_cpu(nmi_touch, cpu) != 1)
 380                                 per_cpu(nmi_touch, cpu) = 1;
 381                 }
 382         }
 383
 384         /*
 385          * Tickle the softlockup detector too:
 386          */
 387         touch_softlockup_watchdog();
 388 }
 389 EXPORT_SYMBOL(touch_nmi_watchdog);
 390
 391 notrace __kprobes int
 392 nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
 393 {
 394         /*
 395          * Since current_thread_info()-> is always on the stack, and we
 396          * always switch the stack NMI-atomically, it's safe to use
 397          * smp_processor_id().
 398          */
 399         unsigned int sum;
 400         int touched = 0;
 401         int cpu = smp_processor_id();
 402         int rc = 0;
 403
 404         /* check for other users first */
 405         if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
 406                         == NOTIFY_STOP) {
 407                 rc = 1;
 408                 touched = 1;
 409         }
 410
 411         sum = get_timer_irqs(cpu);
 412
 413         if (__get_cpu_var(nmi_touch)) {
 414                 __get_cpu_var(nmi_touch) = 0;
 415                 touched = 1;
 416         }
 417
 418         /* We can be called before check_nmi_watchdog, hence NULL check. */
 419         if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
 420                 static DEFINE_RAW_SPINLOCK(lock); /* Serialise the printks */
 421
 422                 raw_spin_lock(&lock);
 423                 printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
 424                 show_regs(regs);
 425                 dump_stack();
 426                 raw_spin_unlock(&lock);
 427                 cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
 428
 429                 rc = 1;
 430         }
 431
 432         /* Could check oops_in_progress here too, but it's safer not to */
 433         if (mce_in_progress())
 434                 touched = 1;
 435
 436         /* if the none of the timers isn't firing, this cpu isn't doing much */
 437         if (!touched && __get_cpu_var(last_irq_sum) == sum) {
 438                 /*
 439                  * Ayiee, looks like this CPU is stuck ...
 440                  * wait a few IRQs (5 seconds) before doing the oops ...
 441                  */
 442                 __this_cpu_inc(alert_counter);
 443                 if (__this_cpu_read(alert_counter) == 5 * nmi_hz)
 444                         /*
 445                          * die_nmi will return ONLY if NOTIFY_STOP happens..
 446                          */
 447                         die_nmi("BUG: NMI Watchdog detected LOCKUP",
 448                                 regs, panic_on_timeout);
 449         } else {
 450                 __get_cpu_var(last_irq_sum) = sum;
 451                 __this_cpu_write(alert_counter, 0);
 452         }
 453
 454         /* see if the nmi watchdog went off */
 455         if (!__get_cpu_var(wd_enabled))
 456                 return rc;
 457         switch (nmi_watchdog) {
 458         case NMI_LOCAL_APIC:
 459                 rc |= lapic_wd_event(nmi_hz);
 460                 break;
 461         case NMI_IO_APIC:
 462                 /*
 463                  * don't know how to accurately check for this.
 464                  * just assume it was a watchdog timer interrupt
 465                  * This matches the old behaviour.
 466                  */
 467                 rc = 1;
 468                 break;
 469         }
 470         return rc;
 471 }
 472
 473 #ifdef CONFIG_SYSCTL
 474
 475 static void enable_ioapic_nmi_watchdog_single(void *unused)
 476 {
 477         __get_cpu_var(wd_enabled) = 1;
 478         atomic_inc(&nmi_active);
 479         __acpi_nmi_enable(NULL);
 480 }
 481
 482 static void enable_ioapic_nmi_watchdog(void)
 483 {
 484         on_each_cpu(enable_ioapic_nmi_watchdog_single, NULL, 1);
 485         touch_nmi_watchdog();
 486 }
 487
 488 static void disable_ioapic_nmi_watchdog(void)
 489 {
 490         on_each_cpu(stop_apic_nmi_watchdog, NULL, 1);
 491 }
 492
 493 static int __init setup_unknown_nmi_panic(char *str)
 494 {
 495         unknown_nmi_panic = 1;
 496         return 1;
 497 }
 498 __setup("unknown_nmi_panic", setup_unknown_nmi_panic);
 499
 500 static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
 501 {
 502         unsigned char reason = get_nmi_reason();
 503         char buf[64];
 504
 505         sprintf(buf, "NMI received for unknown reason %02x\n", reason);
 506         die_nmi(buf, regs, 1); /* Always panic here */
 507         return 0;
 508 }
 509
 510 /*
 511  * proc handler for /proc/sys/kernel/nmi
 512  */
 513 int proc_nmi_enabled(struct ctl_table *table, int write,
 514                         void __user *buffer, size_t *length, loff_t *ppos)
 515 {
 516         int old_state;
 517
 518         nmi_watchdog_enabled = (atomic_read(&nmi_active) > 0) ? 1 : 0;
 519         old_state = nmi_watchdog_enabled;
 520         proc_dointvec(table, write, buffer, length, ppos);
 521         if (!!old_state == !!nmi_watchdog_enabled)
 522                 return 0;
 523
 524         if (atomic_read(&nmi_active) < 0 || !nmi_watchdog_active()) {
 525                 printk(KERN_WARNING
 526                         "NMI watchdog is permanently disabled\n");
 527                 return -EIO;
 528         }
 529
 530         if (nmi_watchdog == NMI_LOCAL_APIC) {
 531                 if (nmi_watchdog_enabled)
 532                         enable_lapic_nmi_watchdog();
 533                 else
 534                         disable_lapic_nmi_watchdog();
 535         } else if (nmi_watchdog == NMI_IO_APIC) {
 536                 if (nmi_watchdog_enabled)
 537                         enable_ioapic_nmi_watchdog();
 538                 else
 539                         disable_ioapic_nmi_watchdog();
 540         } else {
 541                 printk(KERN_WARNING
 542                         "NMI watchdog doesn't know what hardware to touch\n");
 543                 return -EIO;
 544         }
 545         return 0;
 546 }
 547
 548 #endif /* CONFIG_SYSCTL */
 549
 550 int do_nmi_callback(struct pt_regs *regs, int cpu)
 551 {
 552 #ifdef CONFIG_SYSCTL
 553         if (unknown_nmi_panic)
 554                 return unknown_nmi_panic_callback(regs, cpu);
 555 #endif
 556         return 0;
 557 }
 558
 559 void arch_trigger_all_cpu_backtrace(void)
 560 {
 561         int i;
 562
 563         cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
 564
 565         printk(KERN_INFO "sending NMI to all CPUs:\n");
 566         apic->send_IPI_all(NMI_VECTOR);
 567
 568         /* Wait for up to 10 seconds for all CPUs to do the backtrace */
 569         for (i = 0; i < 10 * 1000; i++) {
 570                 if (cpumask_empty(to_cpumask(backtrace_mask)))
 571                         break;
 572                 mdelay(1);
 573         }
 574 }