1/* 2 * linux/arch/x86_64/nmi.c 3 * 4 * NMI watchdog support on APIC systems 5 * 6 * Started by Ingo Molnar <mingo@redhat.com> 7 * 8 * Fixes: 9 * Mikael Pettersson : AMD K7 support for local APIC NMI watchdog. 10 * Mikael Pettersson : Power Management for local APIC NMI watchdog. 11 * Pavel Machek and 12 * Mikael Pettersson : PM converted to driver model. Disable/enable API. 13 */ 14 15#include <linux/nmi.h> 16#include <linux/mm.h> 17#include <linux/delay.h> 18#include <linux/interrupt.h> 19#include <linux/module.h> 20#include <linux/sysdev.h> 21#include <linux/sysctl.h> 22#include <linux/kprobes.h> 23#include <linux/cpumask.h> 24#include <linux/kdebug.h> 25 26#include <asm/smp.h> 27#include <asm/nmi.h> 28#include <asm/proto.h> 29#include <asm/mce.h> 30 31int unknown_nmi_panic; 32int nmi_watchdog_enabled; 33int panic_on_unrecovered_nmi; 34 35static cpumask_t backtrace_mask = CPU_MASK_NONE; 36 37/* nmi_active: 38 * >0: the lapic NMI watchdog is active, but can be disabled 39 * <0: the lapic NMI watchdog has not been set up, and cannot 40 * be enabled 41 * 0: the lapic NMI watchdog is disabled, but can be enabled 42 */ 43atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */ 44int panic_on_timeout; 45 46unsigned int nmi_watchdog = NMI_DEFAULT; 47static unsigned int nmi_hz = HZ; 48 49static DEFINE_PER_CPU(short, wd_enabled); 50 51/* local prototypes */ 52static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu); 53 54/* Run after command line and cpu_init init, but before all other checks */ 55void nmi_watchdog_default(void) 56{ 57 if (nmi_watchdog != NMI_DEFAULT) 58 return; 59 nmi_watchdog = NMI_NONE; 60} 61 62static int endflag __initdata = 0; 63 64#ifdef CONFIG_SMP 65/* The performance counters used by NMI_LOCAL_APIC don't trigger when 66 * the CPU is idle. To make sure the NMI watchdog really ticks on all 67 * CPUs during the test make them busy. 68 */ 69static __init void nmi_cpu_busy(void *data) 70{ 71 local_irq_enable_in_hardirq(); 72 /* Intentionally don't use cpu_relax here. This is 73 to make sure that the performance counter really ticks, 74 even if there is a simulator or similar that catches the 75 pause instruction. On a real HT machine this is fine because 76 all other CPUs are busy with "useless" delay loops and don't 77 care if they get somewhat less cycles. */ 78 while (endflag == 0) 79 mb(); 80} 81#endif 82 83int __init check_nmi_watchdog (void) 84{ 85 int *counts; 86 int cpu; 87 88 if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DEFAULT)) 89 return 0; 90 91 if (!atomic_read(&nmi_active)) 92 return 0; 93 94 counts = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL); 95 if (!counts) 96 return -1; 97 98 printk(KERN_INFO "testing NMI watchdog ... "); 99 100#ifdef CONFIG_SMP 101 if (nmi_watchdog == NMI_LOCAL_APIC) 102 smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0); 103#endif 104 105 for (cpu = 0; cpu < NR_CPUS; cpu++) 106 counts[cpu] = cpu_pda(cpu)->__nmi_count; 107 local_irq_enable(); 108 mdelay((20*1000)/nmi_hz); // wait 20 ticks 109 110 for_each_online_cpu(cpu) { 111 if (!per_cpu(wd_enabled, cpu)) 112 continue; 113 if (cpu_pda(cpu)->__nmi_count - counts[cpu] <= 5) { 114 printk("CPU#%d: NMI appears to be stuck (%d->%d)!\n", 115 cpu, 116 counts[cpu], 117 cpu_pda(cpu)->__nmi_count); 118 per_cpu(wd_enabled, cpu) = 0; 119 atomic_dec(&nmi_active); 120 } 121 } 122 if (!atomic_read(&nmi_active)) { 123 kfree(counts); 124 atomic_set(&nmi_active, -1); 125 endflag = 1; 126 return -1; 127 } 128 endflag = 1; 129 printk("OK.\n"); 130 131 /* now that we know it works we can reduce NMI frequency to 132 something more reasonable; makes a difference in some configs */ 133 if (nmi_watchdog == NMI_LOCAL_APIC) 134 nmi_hz = lapic_adjust_nmi_hz(1); 135 136 kfree(counts); 137 return 0; 138} 139 140int __init setup_nmi_watchdog(char *str) 141{ 142 int nmi; 143 144 if (!strncmp(str,"panic",5)) { 145 panic_on_timeout = 1; 146 str = strchr(str, ','); 147 if (!str) 148 return 1; 149 ++str; 150 } 151 152 get_option(&str, &nmi); 153 154 if ((nmi >= NMI_INVALID) || (nmi < NMI_NONE)) 155 return 0; 156 157 nmi_watchdog = nmi; 158 return 1; 159} 160 161__setup("nmi_watchdog=", setup_nmi_watchdog); 162 163 164static void __acpi_nmi_disable(void *__unused) 165{ 166 apic_write(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED); 167} 168 169/* 170 * Disable timer based NMIs on all CPUs: 171 */ 172void acpi_nmi_disable(void) 173{ 174 if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC) 175 on_each_cpu(__acpi_nmi_disable, NULL, 0, 1); 176} 177 178static void __acpi_nmi_enable(void *__unused) 179{ 180 apic_write(APIC_LVT0, APIC_DM_NMI); 181} 182 183/* 184 * Enable timer based NMIs on all CPUs: 185 */ 186void acpi_nmi_enable(void) 187{ 188 if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC) 189 on_each_cpu(__acpi_nmi_enable, NULL, 0, 1); 190} 191#ifdef CONFIG_PM 192 193static int nmi_pm_active; /* nmi_active before suspend */ 194 195static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state) 196{ 197 /* only CPU0 goes here, other CPUs should be offline */ 198 nmi_pm_active = atomic_read(&nmi_active); 199 stop_apic_nmi_watchdog(NULL); 200 BUG_ON(atomic_read(&nmi_active) != 0); 201 return 0; 202} 203 204static int lapic_nmi_resume(struct sys_device *dev) 205{ 206 /* only CPU0 goes here, other CPUs should be offline */ 207 if (nmi_pm_active > 0) { 208 setup_apic_nmi_watchdog(NULL); 209 touch_nmi_watchdog(); 210 } 211 return 0; 212} 213 214static struct sysdev_class nmi_sysclass = { 215 set_kset_name("lapic_nmi"), 216 .resume = lapic_nmi_resume, 217 .suspend = lapic_nmi_suspend, 218}; 219 220static struct sys_device device_lapic_nmi = { 221 .id = 0, 222 .cls = &nmi_sysclass, 223}; 224 225static int __init init_lapic_nmi_sysfs(void) 226{ 227 int error; 228 229 /* should really be a BUG_ON but b/c this is an 230 * init call, it just doesn't work. -dcz 231 */ 232 if (nmi_watchdog != NMI_LOCAL_APIC) 233 return 0; 234 235 if ( atomic_read(&nmi_active) < 0 ) 236 return 0; 237 238 error = sysdev_class_register(&nmi_sysclass); 239 if (!error) 240 error = sysdev_register(&device_lapic_nmi); 241 return error; 242} 243/* must come after the local APIC's device_initcall() */ 244late_initcall(init_lapic_nmi_sysfs); 245 246#endif /* CONFIG_PM */ 247 248void setup_apic_nmi_watchdog(void *unused) 249{ 250 if (__get_cpu_var(wd_enabled) == 1) 251 return; 252 253 /* cheap hack to support suspend/resume */ 254 /* if cpu0 is not active neither should the other cpus */ 255 if ((smp_processor_id() != 0) && (atomic_read(&nmi_active) <= 0)) 256 return; 257 258 switch (nmi_watchdog) { 259 case NMI_LOCAL_APIC: 260 __get_cpu_var(wd_enabled) = 1; 261 if (lapic_watchdog_init(nmi_hz) < 0) { 262 __get_cpu_var(wd_enabled) = 0; 263 return; 264 } 265 /* FALL THROUGH */ 266 case NMI_IO_APIC: 267 __get_cpu_var(wd_enabled) = 1; 268 atomic_inc(&nmi_active); 269 } 270} 271 272void stop_apic_nmi_watchdog(void *unused) 273{ 274 /* only support LOCAL and IO APICs for now */ 275 if ((nmi_watchdog != NMI_LOCAL_APIC) && 276 (nmi_watchdog != NMI_IO_APIC)) 277 return; 278 if (__get_cpu_var(wd_enabled) == 0) 279 return; 280 if (nmi_watchdog == NMI_LOCAL_APIC) 281 lapic_watchdog_stop(); 282 __get_cpu_var(wd_enabled) = 0; 283 atomic_dec(&nmi_active); 284} 285 286/* 287 * the best way to detect whether a CPU has a 'hard lockup' problem 288 * is to check it's local APIC timer IRQ counts. If they are not 289 * changing then that CPU has some problem. 290 * 291 * as these watchdog NMI IRQs are generated on every CPU, we only 292 * have to check the current processor. 293 */ 294 295static DEFINE_PER_CPU(unsigned, last_irq_sum); 296static DEFINE_PER_CPU(local_t, alert_counter); 297static DEFINE_PER_CPU(int, nmi_touch); 298 299void touch_nmi_watchdog (void) 300{ 301 if (nmi_watchdog > 0) { 302 unsigned cpu; 303 304 /* 305 * Tell other CPUs to reset their alert counters. We cannot 306 * do it ourselves because the alert count increase is not 307 * atomic. 308 */ 309 for_each_present_cpu (cpu) 310 per_cpu(nmi_touch, cpu) = 1; 311 } 312 313 touch_softlockup_watchdog(); 314} 315 316int __kprobes nmi_watchdog_tick(struct pt_regs * regs, unsigned reason) 317{ 318 int sum; 319 int touched = 0; 320 int cpu = smp_processor_id(); 321 int rc = 0; 322 323 /* check for other users first */ 324 if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) 325 == NOTIFY_STOP) { 326 rc = 1; 327 touched = 1; 328 } 329 330 sum = read_pda(apic_timer_irqs); 331 if (__get_cpu_var(nmi_touch)) { 332 __get_cpu_var(nmi_touch) = 0; 333 touched = 1; 334 } 335 336 if (cpu_isset(cpu, backtrace_mask)) { 337 static DEFINE_SPINLOCK(lock); /* Serialise the printks */ 338 339 spin_lock(&lock); 340 printk("NMI backtrace for cpu %d\n", cpu); 341 dump_stack(); 342 spin_unlock(&lock); 343 cpu_clear(cpu, backtrace_mask); 344 } 345 346#ifdef CONFIG_X86_MCE 347 /* Could check oops_in_progress here too, but it's safer 348 not too */ 349 if (atomic_read(&mce_entry) > 0) 350 touched = 1; 351#endif 352 /* if the apic timer isn't firing, this cpu isn't doing much */ 353 if (!touched && __get_cpu_var(last_irq_sum) == sum) { 354 /* 355 * Ayiee, looks like this CPU is stuck ... 356 * wait a few IRQs (5 seconds) before doing the oops ... 357 */ 358 local_inc(&__get_cpu_var(alert_counter)); 359 if (local_read(&__get_cpu_var(alert_counter)) == 5*nmi_hz) 360 die_nmi("NMI Watchdog detected LOCKUP on CPU %d\n", regs, 361 panic_on_timeout); 362 } else { 363 __get_cpu_var(last_irq_sum) = sum; 364 local_set(&__get_cpu_var(alert_counter), 0); 365 } 366 367 /* see if the nmi watchdog went off */ 368 if (!__get_cpu_var(wd_enabled)) 369 return rc; 370 switch (nmi_watchdog) { 371 case NMI_LOCAL_APIC: 372 rc |= lapic_wd_event(nmi_hz); 373 break; 374 case NMI_IO_APIC: 375 /* don't know how to accurately check for this. 376 * just assume it was a watchdog timer interrupt 377 * This matches the old behaviour. 378 */ 379 rc = 1; 380 break; 381 } 382 return rc; 383} 384 385asmlinkage __kprobes void do_nmi(struct pt_regs * regs, long error_code) 386{ 387 nmi_enter(); 388 add_pda(__nmi_count,1); 389 default_do_nmi(regs); 390 nmi_exit(); 391} 392 393int do_nmi_callback(struct pt_regs * regs, int cpu) 394{ 395#ifdef CONFIG_SYSCTL 396 if (unknown_nmi_panic) 397 return unknown_nmi_panic_callback(regs, cpu); 398#endif 399 return 0; 400} 401 402#ifdef CONFIG_SYSCTL 403 404static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu) 405{ 406 unsigned char reason = get_nmi_reason(); 407 char buf[64]; 408 409 sprintf(buf, "NMI received for unknown reason %02x\n", reason); 410 die_nmi(buf, regs, 1); /* Always panic here */ 411 return 0; 412} 413 414/* 415 * proc handler for /proc/sys/kernel/nmi 416 */ 417int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file, 418 void __user *buffer, size_t *length, loff_t *ppos) 419{ 420 int old_state; 421 422 nmi_watchdog_enabled = (atomic_read(&nmi_active) > 0) ? 1 : 0; 423 old_state = nmi_watchdog_enabled; 424 proc_dointvec(table, write, file, buffer, length, ppos); 425 if (!!old_state == !!nmi_watchdog_enabled) 426 return 0; 427 428 if (atomic_read(&nmi_active) < 0) { 429 printk( KERN_WARNING "NMI watchdog is permanently disabled\n"); 430 return -EIO; 431 } 432 433 /* if nmi_watchdog is not set yet, then set it */ 434 nmi_watchdog_default(); 435 436 if (nmi_watchdog == NMI_LOCAL_APIC) { 437 if (nmi_watchdog_enabled) 438 enable_lapic_nmi_watchdog(); 439 else 440 disable_lapic_nmi_watchdog(); 441 } else { 442 printk( KERN_WARNING 443 "NMI watchdog doesn't know what hardware to touch\n"); 444 return -EIO; 445 } 446 return 0; 447} 448 449#endif 450 451void __trigger_all_cpu_backtrace(void) 452{ 453 int i; 454 455 backtrace_mask = cpu_online_map; 456 /* Wait for up to 10 seconds for all CPUs to do the backtrace */ 457 for (i = 0; i < 10 * 1000; i++) { 458 if (cpus_empty(backtrace_mask)) 459 break; 460 mdelay(1); 461 } 462} 463 464EXPORT_SYMBOL(nmi_active); 465EXPORT_SYMBOL(nmi_watchdog); 466EXPORT_SYMBOL(touch_nmi_watchdog); 467