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