/*
* linux/arch/x86_64/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.
* Pavel Machek and
* Mikael Pettersson : PM converted to driver model. Disable/enable API.
*/
#include <linux/config.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/bootmem.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/mc146818rtc.h>
#include <linux/kernel_stat.h>
#include <linux/module.h>
#include <linux/sysdev.h>
#include <linux/nmi.h>
#include <linux/sysctl.h>
#include <linux/kprobes.h>
#include <asm/smp.h>
#include <asm/mtrr.h>
#include <asm/mpspec.h>
#include <asm/nmi.h>
#include <asm/msr.h>
#include <asm/proto.h>
#include <asm/kdebug.h>
#include <asm/local.h>
/*
* lapic_nmi_owner tracks the ownership of the lapic NMI hardware:
* - it may be reserved by some other driver, or not
* - when not reserved by some other driver, it may be used for
* the NMI watchdog, or not
*
* This is maintained separately from nmi_active because the NMI
* watchdog may also be driven from the I/O APIC timer.
*/
static DEFINE_SPINLOCK(lapic_nmi_owner_lock);
static unsigned int lapic_nmi_owner;
#define LAPIC_NMI_WATCHDOG (1<<0)
#define LAPIC_NMI_RESERVED (1<<1)
/* nmi_active:
* +1: the lapic NMI watchdog is active, but can be disabled
* 0: the lapic NMI watchdog has not been set up, and cannot
* be enabled
* -1: the lapic NMI watchdog is disabled, but can be enabled
*/
int nmi_active; /* oprofile uses this */
int panic_on_timeout;
unsigned int nmi_watchdog = NMI_DEFAULT;
static unsigned int nmi_hz = HZ;
static unsigned int nmi_perfctr_msr; /* the MSR to reset in NMI handler */
static unsigned int nmi_p4_cccr_val;
/* Note that these events don't tick when the CPU idles. This means
the frequency varies with CPU load. */
#define K7_EVNTSEL_ENABLE (1 << 22)
#define K7_EVNTSEL_INT (1 << 20)
#define K7_EVNTSEL_OS (1 << 17)
#define K7_EVNTSEL_USR (1 << 16)
#define K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING 0x76
#define K7_NMI_EVENT K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING
#define MSR_P4_MISC_ENABLE 0x1A0
#define MSR_P4_MISC_ENABLE_PERF_AVAIL (1<<7)
#define MSR_P4_MISC_ENABLE_PEBS_UNAVAIL (1<<12)
#define MSR_P4_PERFCTR0 0x300
#define MSR_P4_CCCR0 0x360
#define P4_ESCR_EVENT_SELECT(N) ((N)<<25)
#define P4_ESCR_OS (1<<3)
#define P4_ESCR_USR (1<<2)
#define P4_CCCR_OVF_PMI0 (1<<26)
#define P4_CCCR_OVF_PMI1 (1<<27)
#define P4_CCCR_THRESHOLD(N) ((N)<<20)
#define P4_CCCR_COMPLEMENT (1<<19)
#define P4_CCCR_COMPARE (1<<18)
#define P4_CCCR_REQUIRED (3<<16)
#define P4_CCCR_ESCR_SELECT(N) ((N)<<13)
#define P4_CCCR_ENABLE (1<<12)
/* Set up IQ_COUNTER0 to behave like a clock, by having IQ_CCCR0 filter
CRU_ESCR0 (with any non-null event selector) through a complemented
max threshold. [IA32-Vol3, Section 14.9.9] */
#define MSR_P4_IQ_COUNTER0 0x30C
#define P4_NMI_CRU_ESCR0 (P4_ESCR_EVENT_SELECT(0x3F)|P4_ESCR_OS|P4_ESCR_USR)
#define P4_NMI_IQ_CCCR0 \
(P4_CCCR_OVF_PMI0|P4_CCCR_THRESHOLD(15)|P4_CCCR_COMPLEMENT| \
P4_CCCR_COMPARE|P4_CCCR_REQUIRED|P4_CCCR_ESCR_SELECT(4)|P4_CCCR_ENABLE)
static __cpuinit inline int nmi_known_cpu(void)
{
switch (boot_cpu_data.x86_vendor) {
case X86_VENDOR_AMD:
return boot_cpu_data.x86 == 15;
case X86_VENDOR_INTEL:
return boot_cpu_data.x86 == 15;
}
return 0;
}
/* Run after command line and cpu_init init, but before all other checks */
void __cpuinit nmi_watchdog_default(void)
{
if (nmi_watchdog != NMI_DEFAULT)
return;
if (nmi_known_cpu())
nmi_watchdog = NMI_LOCAL_APIC;
else
nmi_watchdog = NMI_IO_APIC;
}
#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)
{
volatile int *endflag = data;
local_irq_enable();
/* 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)
barrier();
}
#endif
int __init check_nmi_watchdog (void)
{
volatile int endflag = 0;
int *counts;
int cpu;
counts = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
if (!counts)
return -1;
printk(KERN_INFO "testing NMI watchdog ... ");
#ifdef CONFIG_SMP
if (nmi_watchdog == NMI_LOCAL_APIC)
smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0);
#endif
for (cpu = 0; cpu < NR_CPUS; cpu++)
counts[cpu] = cpu_pda(cpu)->__nmi_count;
local_irq_enable();
mdelay((10*1000)/nmi_hz); // wait 10 ticks
for (cpu = 0; cpu < NR_CPUS; cpu++) {
if (!cpu_online(cpu))
continue;
if (cpu_pda(cpu)->__nmi_count - counts[cpu] <= 5) {
endflag = 1;
printk("CPU#%d: NMI appears to be stuck (%d->%d)!\n",
cpu,
counts[cpu],
cpu_pda(cpu)->__nmi_count);
nmi_active = 0;
lapic_nmi_owner &= ~LAPIC_NMI_WATCHDOG;
nmi_perfctr_msr = 0;
kfree(counts);
return -1;
}
}
endflag = 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 = 1;
kfree(counts);
return 0;
}
int __init setup_nmi_watchdog(char *str)
{
int nmi;
if (!strncmp(str,"panic",5)) {
panic_on_timeout = 1;
str = strchr(str, ',');
if (!str)
return 1;
++str;
}
get_option(&str, &nmi);
if (nmi >= NMI_INVALID)
return 0;
nmi_watchdog = nmi;
return 1;
}
__setup("nmi_watchdog=", setup_nmi_watchdog);
static void disable_lapic_nmi_watchdog(void)
{
if (nmi_active <= 0)
return;
switch (boot_cpu_data.x86_vendor) {
case X86_VENDOR_AMD:
wrmsr(MSR_K7_EVNTSEL0, 0, 0);
break;
case X86_VENDOR_INTEL:
if (boot_cpu_data.x86 == 15) {
wrmsr(MSR_P4_IQ_CCCR0, 0, 0);
wrmsr(MSR_P4_CRU_ESCR0, 0, 0);
}
break;
}
nmi_active = -1;
/* tell do_nmi() and others that we're not active any more */
nmi_watchdog = 0;
}
static void enable_lapic_nmi_watchdog(void)
{
if (nmi_active < 0) {
nmi_watchdog = NMI_LOCAL_APIC;
touch_nmi_watchdog();
setup_apic_nmi_watchdog();
}
}
int reserve_lapic_nmi(void)
{
unsigned int old_owner;
spin_lock(&lapic_nmi_owner_lock);
old_owner = lapic_nmi_owner;
lapic_nmi_owner |= LAPIC_NMI_RESERVED;
spin_unlock(&lapic_nmi_owner_lock);
if (old_owner & LAPIC_NMI_RESERVED)
return -EBUSY;
if (old_owner & LAPIC_NMI_WATCHDOG)
disable_lapic_nmi_watchdog();
return 0;
}
void release_lapic_nmi(void)
{
unsigned int new_owner;
spin_lock(&lapic_nmi_owner_lock);
new_owner = lapic_nmi_owner & ~LAPIC_NMI_RESERVED;
lapic_nmi_owner = new_owner;
spin_unlock(&lapic_nmi_owner_lock);
if (new_owner & LAPIC_NMI_WATCHDOG)
enable_lapic_nmi_watchdog();
}
void disable_timer_nmi_watchdog(void)
{
if ((nmi_watchdog != NMI_IO_APIC) || (nmi_active <= 0))
return;
disable_irq(0);
unset_nmi_callback();
nmi_active = -1;
nmi_watchdog = NMI_NONE;
}
void enable_timer_nmi_watchdog(void)
{
if (nmi_active < 0) {
nmi_watchdog = NMI_IO_APIC;
touch_nmi_watchdog();
nmi_active = 1;
enable_irq(0);
}
}
#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)
{
nmi_pm_active = nmi_active;
disable_lapic_nmi_watchdog();
return 0;
}
static int lapic_nmi_resume(struct sys_device *dev)
{
if (nmi_pm_active > 0)
enable_lapic_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;
if (nmi_active == 0 || nmi_watchdog != NMI_LOCAL_APIC)
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 */
/*
* Activate the NMI watchdog via the local APIC.
* Original code written by Keith Owens.
*/
static void clear_msr_range(unsigned int base, unsigned int n)
{
unsigned int i;
for(i = 0; i < n; ++i)
wrmsr(base+i, 0, 0);
}
static void setup_k7_watchdog(void)
{
int i;
unsigned int evntsel;
nmi_perfctr_msr = MSR_K7_PERFCTR0;
for(i = 0; i < 4; ++i) {
/* Simulator may not support it */
if (checking_wrmsrl(MSR_K7_EVNTSEL0+i, 0UL)) {
nmi_perfctr_msr = 0;
return;
}
wrmsrl(MSR_K7_PERFCTR0+i, 0UL);
}
evntsel = K7_EVNTSEL_INT
| K7_EVNTSEL_OS
| K7_EVNTSEL_USR
| K7_NMI_EVENT;
wrmsr(MSR_K7_EVNTSEL0, evntsel, 0);
wrmsrl(MSR_K7_PERFCTR0, -((u64)cpu_khz * 1000 / nmi_hz));
apic_write(APIC_LVTPC, APIC_DM_NMI);
evntsel |= K7_EVNTSEL_ENABLE;
wrmsr(MSR_K7_EVNTSEL0, evntsel, 0);
}
static int setup_p4_watchdog(void)
{
unsigned int misc_enable, dummy;
rdmsr(MSR_P4_MISC_ENABLE, misc_enable, dummy);
if (!(misc_enable & MSR_P4_MISC_ENABLE_PERF_AVAIL))
return 0;
nmi_perfctr_msr = MSR_P4_IQ_COUNTER0;
nmi_p4_cccr_val = P4_NMI_IQ_CCCR0;
#ifdef CONFIG_SMP
if (smp_num_siblings == 2)
nmi_p4_cccr_val |= P4_CCCR_OVF_PMI1;
#endif
if (!(misc_enable & MSR_P4_MISC_ENABLE_PEBS_UNAVAIL))
clear_msr_range(0x3F1, 2);
/* MSR 0x3F0 seems to have a default value of 0xFC00, but current
docs doesn't fully define it, so leave it alone for now. */
if (boot_cpu_data.x86_model >= 0x3) {
/* MSR_P4_IQ_ESCR0/1 (0x3ba/0x3bb) removed */
clear_msr_range(0x3A0, 26);
clear_msr_range(0x3BC, 3);
} else {
clear_msr_range(0x3A0, 31);
}
clear_msr_range(0x3C0, 6);
clear_msr_range(0x3C8, 6);
clear_msr_range(0x3E0, 2);
clear_msr_range(MSR_P4_CCCR0, 18);
clear_msr_range(MSR_P4_PERFCTR0, 18);
wrmsr(MSR_P4_CRU_ESCR0, P4_NMI_CRU_ESCR0, 0);
wrmsr(MSR_P4_IQ_CCCR0, P4_NMI_IQ_CCCR0 & ~P4_CCCR_ENABLE, 0);
Dprintk("setting P4_IQ_COUNTER0 to 0x%08lx\n", -(cpu_khz * 1000UL / nmi_hz));
wrmsrl(MSR_P4_IQ_COUNTER0, -((u64)cpu_khz * 1000 / nmi_hz));
apic_write(APIC_LVTPC, APIC_DM_NMI);
wrmsr(MSR_P4_IQ_CCCR0, nmi_p4_cccr_val, 0);
return 1;
}
void setup_apic_nmi_watchdog(void)
{
switch (boot_cpu_data.x86_vendor) {
case X86_VENDOR_AMD:
if (boot_cpu_data.x86 != 15)
return;
if (strstr(boot_cpu_data.x86_model_id, "Screwdriver"))
return;
setup_k7_watchdog();
break;
case X86_VENDOR_INTEL:
if (boot_cpu_data.x86 != 15)
return;
if (!setup_p4_watchdog())
return;
break;
default:
return;
}
lapic_nmi_owner = LAPIC_NMI_WATCHDOG;
nmi_active = 1;
}
/*
* 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.
*/
static DEFINE_PER_CPU(unsigned, last_irq_sum);
static DEFINE_PER_CPU(local_t, alert_counter);
static DEFINE_PER_CPU(int, nmi_touch);
void touch_nmi_watchdog (void)
{
if (nmi_watchdog > 0) {
unsigned cpu;
/*
* Tell other CPUs to reset their alert counters. We cannot
* do it ourselves because the alert count increase is not
* atomic.
*/
for_each_present_cpu (cpu)
per_cpu(nmi_touch, cpu) = 1;
}
touch_softlockup_watchdog();
}
void __kprobes nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
{
int sum;
int touched = 0;
sum = read_pda(apic_timer_irqs);
if (__get_cpu_var(nmi_touch)) {
__get_cpu_var(nmi_touch) = 0;
touched = 1;
}
if (!touched && __get_cpu_var(last_irq_sum) == sum) {
/*
* Ayiee, looks like this CPU is stuck ...
* wait a few IRQs (5 seconds) before doing the oops ...
*/
local_inc(&__get_cpu_var(alert_counter));
if (local_read(&__get_cpu_var(alert_counter)) == 5*nmi_hz) {
if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
== NOTIFY_STOP) {
local_set(&__get_cpu_var(alert_counter), 0);
return;
}
die_nmi("NMI Watchdog detected LOCKUP on CPU %d\n", regs);
}
} else {
__get_cpu_var(last_irq_sum) = sum;
local_set(&__get_cpu_var(alert_counter), 0);
}
if (nmi_perfctr_msr) {
if (nmi_perfctr_msr == MSR_P4_IQ_COUNTER0) {
/*
* P4 quirks:
* - An overflown perfctr will assert its interrupt
* until the OVF flag in its CCCR is cleared.
* - LVTPC is masked on interrupt and must be
* unmasked by the LVTPC handler.
*/
wrmsr(MSR_P4_IQ_CCCR0, nmi_p4_cccr_val, 0);
apic_write(APIC_LVTPC, APIC_DM_NMI);
}
wrmsrl(nmi_perfctr_msr, -((u64)cpu_khz * 1000 / nmi_hz));
}
}
static __kprobes int dummy_nmi_callback(struct pt_regs * regs, int cpu)
{
return 0;
}
static nmi_callback_t nmi_callback = dummy_nmi_callback;
asmlinkage __kprobes void do_nmi(struct pt_regs * regs, long error_code)
{
int cpu = safe_smp_processor_id();
nmi_enter();
add_pda(__nmi_count,1);
if (!rcu_dereference(nmi_callback)(regs, cpu))
default_do_nmi(regs);
nmi_exit();
}
void set_nmi_callback(nmi_callback_t callback)
{
rcu_assign_pointer(nmi_callback, callback);
}
void unset_nmi_callback(void)
{
nmi_callback = dummy_nmi_callback;
}
#ifdef CONFIG_SYSCTL
static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
{
unsigned char reason = get_nmi_reason();
char buf[64];
if (!(reason & 0xc0)) {
sprintf(buf, "NMI received for unknown reason %02x\n", reason);
die_nmi(buf,regs);
}
return 0;
}
/*
* proc handler for /proc/sys/kernel/unknown_nmi_panic
*/
int proc_unknown_nmi_panic(struct ctl_table *table, int write, struct file *file,
void __user *buffer, size_t *length, loff_t *ppos)
{
int old_state;
old_state = unknown_nmi_panic;
proc_dointvec(table, write, file, buffer, length, ppos);
if (!!old_state == !!unknown_nmi_panic)
return 0;
if (unknown_nmi_panic) {
if (reserve_lapic_nmi() < 0) {
unknown_nmi_panic = 0;
return -EBUSY;
} else {
set_nmi_callback(unknown_nmi_panic_callback);
}
} else {
release_lapic_nmi();
unset_nmi_callback();
}
return 0;
}
#endif
EXPORT_SYMBOL(nmi_active);
EXPORT_SYMBOL(nmi_watchdog);
EXPORT_SYMBOL(reserve_lapic_nmi);
EXPORT_SYMBOL(release_lapic_nmi);
EXPORT_SYMBOL(disable_timer_nmi_watchdog);
EXPORT_SYMBOL(enable_timer_nmi_watchdog);
EXPORT_SYMBOL(touch_nmi_watchdog);
