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[/] [or1k_soc_on_altera_embedded_dev_kit/] [trunk/] [linux-2.6/] [linux-2.6.24/] [arch/] [x86/] [kernel/] [nmi_32.c] - Rev 3
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/* * NMI watchdog support on APIC systems * * Started by Ingo Molnar <mingo@redhat.com> * * Fixes: * Mikael Pettersson : AMD K7 support for local APIC NMI watchdog. * Mikael Pettersson : Power Management for local APIC NMI watchdog. * Mikael Pettersson : Pentium 4 support for local APIC NMI watchdog. * Pavel Machek and * Mikael Pettersson : PM converted to driver model. Disable/enable API. */ #include <linux/delay.h> #include <linux/interrupt.h> #include <linux/module.h> #include <linux/nmi.h> #include <linux/sysdev.h> #include <linux/sysctl.h> #include <linux/percpu.h> #include <linux/kprobes.h> #include <linux/cpumask.h> #include <linux/kernel_stat.h> #include <linux/kdebug.h> #include <asm/smp.h> #include <asm/nmi.h> #include "mach_traps.h" int unknown_nmi_panic; int nmi_watchdog_enabled; static cpumask_t backtrace_mask = CPU_MASK_NONE; /* nmi_active: * >0: the lapic NMI watchdog is active, but can be disabled * <0: the lapic NMI watchdog has not been set up, and cannot * be enabled * 0: the lapic NMI watchdog is disabled, but can be enabled */ atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */ unsigned int nmi_watchdog = NMI_DEFAULT; static unsigned int nmi_hz = HZ; static DEFINE_PER_CPU(short, wd_enabled); /* local prototypes */ static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu); static int endflag __initdata = 0; /* The performance counters used by NMI_LOCAL_APIC don't trigger when * the CPU is idle. To make sure the NMI watchdog really ticks on all * CPUs during the test make them busy. */ static __init void nmi_cpu_busy(void *data) { #ifdef CONFIG_SMP local_irq_enable_in_hardirq(); /* Intentionally don't use cpu_relax here. This is to make sure that the performance counter really ticks, even if there is a simulator or similar that catches the pause instruction. On a real HT machine this is fine because all other CPUs are busy with "useless" delay loops and don't care if they get somewhat less cycles. */ while (endflag == 0) mb(); #endif } static int __init check_nmi_watchdog(void) { unsigned int *prev_nmi_count; int cpu; if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DISABLED)) return 0; if (!atomic_read(&nmi_active)) return 0; prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL); if (!prev_nmi_count) return -1; printk(KERN_INFO "Testing NMI watchdog ... "); if (nmi_watchdog == NMI_LOCAL_APIC) smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0); for_each_possible_cpu(cpu) prev_nmi_count[cpu] = per_cpu(irq_stat, cpu).__nmi_count; local_irq_enable(); mdelay((20*1000)/nmi_hz); // wait 20 ticks for_each_possible_cpu(cpu) { #ifdef CONFIG_SMP /* Check cpu_callin_map here because that is set after the timer is started. */ if (!cpu_isset(cpu, cpu_callin_map)) continue; #endif if (!per_cpu(wd_enabled, cpu)) continue; if (nmi_count(cpu) - prev_nmi_count[cpu] <= 5) { printk(KERN_WARNING "WARNING: CPU#%d: NMI " "appears to be stuck (%d->%d)!\n", cpu, prev_nmi_count[cpu], nmi_count(cpu)); per_cpu(wd_enabled, cpu) = 0; atomic_dec(&nmi_active); } } endflag = 1; if (!atomic_read(&nmi_active)) { kfree(prev_nmi_count); atomic_set(&nmi_active, -1); return -1; } printk("OK.\n"); /* now that we know it works we can reduce NMI frequency to something more reasonable; makes a difference in some configs */ if (nmi_watchdog == NMI_LOCAL_APIC) nmi_hz = lapic_adjust_nmi_hz(1); kfree(prev_nmi_count); return 0; } /* This needs to happen later in boot so counters are working */ late_initcall(check_nmi_watchdog); static int __init setup_nmi_watchdog(char *str) { int nmi; get_option(&str, &nmi); if ((nmi >= NMI_INVALID) || (nmi < NMI_NONE)) return 0; nmi_watchdog = nmi; return 1; } __setup("nmi_watchdog=", setup_nmi_watchdog); /* Suspend/resume support */ #ifdef CONFIG_PM static int nmi_pm_active; /* nmi_active before suspend */ static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state) { /* only CPU0 goes here, other CPUs should be offline */ nmi_pm_active = atomic_read(&nmi_active); stop_apic_nmi_watchdog(NULL); BUG_ON(atomic_read(&nmi_active) != 0); return 0; } static int lapic_nmi_resume(struct sys_device *dev) { /* only CPU0 goes here, other CPUs should be offline */ if (nmi_pm_active > 0) { setup_apic_nmi_watchdog(NULL); touch_nmi_watchdog(); } return 0; } static struct sysdev_class nmi_sysclass = { set_kset_name("lapic_nmi"), .resume = lapic_nmi_resume, .suspend = lapic_nmi_suspend, }; static struct sys_device device_lapic_nmi = { .id = 0, .cls = &nmi_sysclass, }; static int __init init_lapic_nmi_sysfs(void) { int error; /* should really be a BUG_ON but b/c this is an * init call, it just doesn't work. -dcz */ if (nmi_watchdog != NMI_LOCAL_APIC) return 0; if (atomic_read(&nmi_active) < 0) return 0; error = sysdev_class_register(&nmi_sysclass); if (!error) error = sysdev_register(&device_lapic_nmi); return error; } /* must come after the local APIC's device_initcall() */ late_initcall(init_lapic_nmi_sysfs); #endif /* CONFIG_PM */ static void __acpi_nmi_enable(void *__unused) { apic_write_around(APIC_LVT0, APIC_DM_NMI); } /* * Enable timer based NMIs on all CPUs: */ void acpi_nmi_enable(void) { if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC) on_each_cpu(__acpi_nmi_enable, NULL, 0, 1); } static void __acpi_nmi_disable(void *__unused) { apic_write(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED); } /* * Disable timer based NMIs on all CPUs: */ void acpi_nmi_disable(void) { if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC) on_each_cpu(__acpi_nmi_disable, NULL, 0, 1); } void setup_apic_nmi_watchdog (void *unused) { if (__get_cpu_var(wd_enabled)) return; /* cheap hack to support suspend/resume */ /* if cpu0 is not active neither should the other cpus */ if ((smp_processor_id() != 0) && (atomic_read(&nmi_active) <= 0)) return; switch (nmi_watchdog) { case NMI_LOCAL_APIC: __get_cpu_var(wd_enabled) = 1; /* enable it before to avoid race with handler */ if (lapic_watchdog_init(nmi_hz) < 0) { __get_cpu_var(wd_enabled) = 0; return; } /* FALL THROUGH */ case NMI_IO_APIC: __get_cpu_var(wd_enabled) = 1; atomic_inc(&nmi_active); } } void stop_apic_nmi_watchdog(void *unused) { /* only support LOCAL and IO APICs for now */ if ((nmi_watchdog != NMI_LOCAL_APIC) && (nmi_watchdog != NMI_IO_APIC)) return; if (__get_cpu_var(wd_enabled) == 0) return; if (nmi_watchdog == NMI_LOCAL_APIC) lapic_watchdog_stop(); __get_cpu_var(wd_enabled) = 0; atomic_dec(&nmi_active); } /* * the best way to detect whether a CPU has a 'hard lockup' problem * is to check it's local APIC timer IRQ counts. If they are not * changing then that CPU has some problem. * * as these watchdog NMI IRQs are generated on every CPU, we only * have to check the current processor. * * since NMIs don't listen to _any_ locks, we have to be extremely * careful not to rely on unsafe variables. The printk might lock * up though, so we have to break up any console locks first ... * [when there will be more tty-related locks, break them up * here too!] */ static unsigned int last_irq_sums [NR_CPUS], alert_counter [NR_CPUS]; void touch_nmi_watchdog(void) { if (nmi_watchdog > 0) { unsigned cpu; /* * Just reset the alert counters, (other CPUs might be * spinning on locks we hold): */ for_each_present_cpu(cpu) { if (alert_counter[cpu]) alert_counter[cpu] = 0; } } /* * Tickle the softlockup detector too: */ touch_softlockup_watchdog(); } EXPORT_SYMBOL(touch_nmi_watchdog); extern void die_nmi(struct pt_regs *, const char *msg); __kprobes int nmi_watchdog_tick(struct pt_regs * regs, unsigned reason) { /* * Since current_thread_info()-> is always on the stack, and we * always switch the stack NMI-atomically, it's safe to use * smp_processor_id(). */ unsigned int sum; int touched = 0; int cpu = smp_processor_id(); int rc=0; /* check for other users first */ if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP) { rc = 1; touched = 1; } if (cpu_isset(cpu, backtrace_mask)) { static DEFINE_SPINLOCK(lock); /* Serialise the printks */ spin_lock(&lock); printk("NMI backtrace for cpu %d\n", cpu); dump_stack(); spin_unlock(&lock); cpu_clear(cpu, backtrace_mask); } /* * Take the local apic timer and PIT/HPET into account. We don't * know which one is active, when we have highres/dyntick on */ sum = per_cpu(irq_stat, cpu).apic_timer_irqs + per_cpu(irq_stat, cpu).irq0_irqs; /* if the none of the timers isn't firing, this cpu isn't doing much */ if (!touched && last_irq_sums[cpu] == sum) { /* * Ayiee, looks like this CPU is stuck ... * wait a few IRQs (5 seconds) before doing the oops ... */ alert_counter[cpu]++; if (alert_counter[cpu] == 5*nmi_hz) /* * die_nmi will return ONLY if NOTIFY_STOP happens.. */ die_nmi(regs, "BUG: NMI Watchdog detected LOCKUP"); } else { last_irq_sums[cpu] = sum; alert_counter[cpu] = 0; } /* see if the nmi watchdog went off */ if (!__get_cpu_var(wd_enabled)) return rc; switch (nmi_watchdog) { case NMI_LOCAL_APIC: rc |= lapic_wd_event(nmi_hz); break; case NMI_IO_APIC: /* don't know how to accurately check for this. * just assume it was a watchdog timer interrupt * This matches the old behaviour. */ rc = 1; break; } return rc; } int do_nmi_callback(struct pt_regs * regs, int cpu) { #ifdef CONFIG_SYSCTL if (unknown_nmi_panic) return unknown_nmi_panic_callback(regs, cpu); #endif return 0; } #ifdef CONFIG_SYSCTL static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu) { unsigned char reason = get_nmi_reason(); char buf[64]; sprintf(buf, "NMI received for unknown reason %02x\n", reason); die_nmi(regs, buf); return 0; } /* * proc handler for /proc/sys/kernel/nmi */ int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file, void __user *buffer, size_t *length, loff_t *ppos) { int old_state; nmi_watchdog_enabled = (atomic_read(&nmi_active) > 0) ? 1 : 0; old_state = nmi_watchdog_enabled; proc_dointvec(table, write, file, buffer, length, ppos); if (!!old_state == !!nmi_watchdog_enabled) return 0; if (atomic_read(&nmi_active) < 0 || nmi_watchdog == NMI_DISABLED) { printk( KERN_WARNING "NMI watchdog is permanently disabled\n"); return -EIO; } if (nmi_watchdog == NMI_DEFAULT) { if (lapic_watchdog_ok()) nmi_watchdog = NMI_LOCAL_APIC; else nmi_watchdog = NMI_IO_APIC; } if (nmi_watchdog == NMI_LOCAL_APIC) { if (nmi_watchdog_enabled) enable_lapic_nmi_watchdog(); else disable_lapic_nmi_watchdog(); } else { printk( KERN_WARNING "NMI watchdog doesn't know what hardware to touch\n"); return -EIO; } return 0; } #endif void __trigger_all_cpu_backtrace(void) { int i; backtrace_mask = cpu_online_map; /* Wait for up to 10 seconds for all CPUs to do the backtrace */ for (i = 0; i < 10 * 1000; i++) { if (cpus_empty(backtrace_mask)) break; mdelay(1); } } EXPORT_SYMBOL(nmi_active); EXPORT_SYMBOL(nmi_watchdog);