1 files changed, 468 insertions, 0 deletions
diff --git a/arch/x86/kernel/nmi_32.c b/arch/x86/kernel/nmi_32.c
new file mode 100644
index 000000000000..c7227e2180f8
--- /dev/null
+++ b/arch/x86/kernel/nmi_32.c
@@ -0,0 +1,468 @@
+/*
+ *  linux/arch/i386/nmi.c
+ *
+ *  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;
+
+#ifdef CONFIG_SMP
+/* 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)
+{
+	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("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 + kstat_cpu(cpu).irqs[0];
+
+	/* 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);