/* Pseudo NMI support on sparc64 systems.
*
* Copyright (C) 2009 David S. Miller <davem@davemloft.net>
*
* The NMI watchdog support and infrastructure is based almost
* entirely upon the x86 NMI support code.
*/
#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"
/* We don't have a real NMI on sparc64, but we can fake one
* up using profiling counter overflow interrupts and interrupt
* levels.
*
* The profile overflow interrupts at level 15, so we use
* level 14 as our IRQ off level.
*/
static int panic_on_timeout;
/* nmi_active:
* >0: the NMI watchdog is active, but can be disabled
* <0: the NMI watchdog has not been set up, and cannot be enabled
* 0: the NMI watchdog is disabled, but can be enabled
*/
atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */
EXPORT_SYMBOL(nmi_active);
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 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;
}
}
touch_softlockup_watchdog();
}
EXPORT_SYMBOL(touch_nmi_watchdog);
static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
{
if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
return;
console_verbose();
bust_spinlocks(1);
printk(KERN_EMERG "%s", str);
printk(" on CPU%d, ip %08lx, registers:\n",
smp_processor_id(), regs->tpc);
show_regs(regs);
dump_stack();
bust_spinlocks(0);
if (do_panic || panic_on_oops)
panic("Non maskable interrupt");
nmi_exit();
local_irq_enable();
do_exit(SIGBUS);
}
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 (__get_cpu_var(nmi_touch)) {
__get_cpu_var(nmi_touch) = 0;
touched = 1;
}
if (!touched && __get_cpu_var(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 {
__get_cpu_var(last_irq_sum) = sum;
__this_cpu_write(alert_counter, 0);
}
if (__get_cpu_var(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)
{
local_irq_enable_in_hardirq();
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)
{
pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
__get_cpu_var(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(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); /* wait 20 ticks */
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)
{
__get_cpu_var(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 (!__get_cpu_var(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);
}
}
return err;
}
static int __init setup_nmi_watchdog(char *str)
{
if (!strncmp(str, "panic", 5))
panic_on_timeout = 1;
return 0;
}
__setup("nmi_watchdog=", setup_nmi_watchdog);
