#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/init.h>
#include <linux/percpu.h>
#include <linux/nmi.h>
#include <linux/export.h>
#include <linux/kprobes.h>
#include <linux/kernel_stat.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/kdebug.h>
#include <linux/delay.h>
#include <linux/smp.h>
#include <asm/perf_event.h>
#include <asm/ptrace.h>
#include <asm/pcr.h>
#include "kstack.h"
static int panic_on_timeout;
atomic_t nmi_active = ATOMIC_INIT(0);
EXPORT_SYMBOL(nmi_active);
static int nmi_init_done;
static unsigned int nmi_hz = HZ;
static DEFINE_PER_CPU(short, wd_enabled);
static int endflag __initdata;
static DEFINE_PER_CPU(unsigned int, last_irq_sum);
static DEFINE_PER_CPU(long, alert_counter);
static DEFINE_PER_CPU(int, nmi_touch);
void arch_touch_nmi_watchdog(void)
{
if (atomic_read(&nmi_active)) {
int cpu;
for_each_present_cpu(cpu) {
if (per_cpu(nmi_touch, cpu) != 1)
per_cpu(nmi_touch, cpu) = 1;
}
}
}
EXPORT_SYMBOL(arch_touch_nmi_watchdog);
int __init watchdog_hardlockup_probe(void)
{
return 0;
}
static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
{
int this_cpu = smp_processor_id();
if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
return;
if (do_panic || panic_on_oops)
panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
else
WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
}
notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
{
unsigned int sum, touched = 0;
void *orig_sp;
clear_softint(1 << irq);
local_cpu_data().__nmi_count++;
nmi_enter();
orig_sp = set_hardirq_stack();
if (notify_die(DIE_NMI, "nmi", regs, 0,
pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
touched = 1;
else
pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
sum = local_cpu_data().irq0_irqs;
if (__this_cpu_read(nmi_touch)) {
__this_cpu_write(nmi_touch, 0);
touched = 1;
}
if (!touched && __this_cpu_read(last_irq_sum) == sum) {
__this_cpu_inc(alert_counter);
if (__this_cpu_read(alert_counter) == 30 * nmi_hz)
die_nmi("BUG: NMI Watchdog detected LOCKUP",
regs, panic_on_timeout);
} else {
__this_cpu_write(last_irq_sum, sum);
__this_cpu_write(alert_counter, 0);
}
if (__this_cpu_read(wd_enabled)) {
pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
}
restore_hardirq_stack(orig_sp);
nmi_exit();
}
static inline unsigned int get_nmi_count(int cpu)
{
return cpu_data(cpu).__nmi_count;
}
static __init void nmi_cpu_busy(void *data)
{
while (endflag == 0)
mb();
}
static void report_broken_nmi(int cpu, int *prev_nmi_count)
{
printk(KERN_CONT "\n");
printk(KERN_WARNING
"WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
printk(KERN_WARNING
"Please report this to bugzilla.kernel.org,\n");
printk(KERN_WARNING
"and attach the output of the 'dmesg' command.\n");
per_cpu(wd_enabled, cpu) = 0;
atomic_dec(&nmi_active);
}
void stop_nmi_watchdog(void *unused)
{
if (!__this_cpu_read(wd_enabled))
return;
pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
__this_cpu_write(wd_enabled, 0);
atomic_dec(&nmi_active);
}
static int __init check_nmi_watchdog(void)
{
unsigned int *prev_nmi_count;
int cpu, err;
if (!atomic_read(&nmi_active))
return 0;
prev_nmi_count = kmalloc_array(nr_cpu_ids, sizeof(unsigned int),
GFP_KERNEL);
if (!prev_nmi_count) {
err = -ENOMEM;
goto error;
}
printk(KERN_INFO "Testing NMI watchdog ... ");
smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
for_each_possible_cpu(cpu)
prev_nmi_count[cpu] = get_nmi_count(cpu);
local_irq_enable();
mdelay((20 * 1000) / nmi_hz);
for_each_online_cpu(cpu) {
if (!per_cpu(wd_enabled, cpu))
continue;
if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
report_broken_nmi(cpu, prev_nmi_count);
}
endflag = 1;
if (!atomic_read(&nmi_active)) {
kfree(prev_nmi_count);
atomic_set(&nmi_active, -1);
err = -ENODEV;
goto error;
}
printk("OK.\n");
nmi_hz = 1;
kfree(prev_nmi_count);
return 0;
error:
on_each_cpu(stop_nmi_watchdog, NULL, 1);
return err;
}
void start_nmi_watchdog(void *unused)
{
if (__this_cpu_read(wd_enabled))
return;
__this_cpu_write(wd_enabled, 1);
atomic_inc(&nmi_active);
pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
}
static void nmi_adjust_hz_one(void *unused)
{
if (!__this_cpu_read(wd_enabled))
return;
pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
}
void nmi_adjust_hz(unsigned int new_hz)
{
nmi_hz = new_hz;
on_each_cpu(nmi_adjust_hz_one, NULL, 1);
}
EXPORT_SYMBOL_GPL(nmi_adjust_hz);
static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
{
on_each_cpu(stop_nmi_watchdog, NULL, 1);
return 0;
}
static struct notifier_block nmi_reboot_notifier = {
.notifier_call = nmi_shutdown,
};
int __init nmi_init(void)
{
int err;
on_each_cpu(start_nmi_watchdog, NULL, 1);
err = check_nmi_watchdog();
if (!err) {
err = register_reboot_notifier(&nmi_reboot_notifier);
if (err) {
on_each_cpu(stop_nmi_watchdog, NULL, 1);
atomic_set(&nmi_active, -1);
}
}
nmi_init_done = 1;
return err;
}
static int __init setup_nmi_watchdog(char *str)
{
if (!strncmp(str, "panic", 5))
panic_on_timeout = 1;
return 1;
}
__setup("nmi_watchdog=", setup_nmi_watchdog);
void watchdog_hardlockup_enable(unsigned int cpu)
{
if (atomic_read(&nmi_active) == -1) {
pr_warn("NMI watchdog cannot be enabled or disabled\n");
return;
}
if (!nmi_init_done)
return;
smp_call_function_single(cpu, start_nmi_watchdog, NULL, 1);
}
void watchdog_hardlockup_disable(unsigned int cpu)
{
if (atomic_read(&nmi_active) == -1)
pr_warn_once("NMI watchdog cannot be enabled or disabled\n");
else
smp_call_function_single(cpu, stop_nmi_watchdog, NULL, 1);
}
