[mirror_ubuntu-artful-kernel.git] / arch / i386 / kernel / nmi.c

/*
 *  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/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/nmi.h>
#include <linux/sysdev.h>
#include <linux/sysctl.h>

#include <asm/smp.h>
#include <asm/div64.h>
#include <asm/nmi.h>

#include "mach_traps.h"

unsigned int nmi_watchdog = NMI_NONE;
extern int unknown_nmi_panic;
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;
extern void show_registers(struct pt_regs *regs);

/*
 * 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;

#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 P6_EVNTSEL0_ENABLE      (1 << 22)
#define P6_EVNTSEL_INT          (1 << 20)
#define P6_EVNTSEL_OS           (1 << 17)
#define P6_EVNTSEL_USR          (1 << 16)
#define P6_EVENT_CPU_CLOCKS_NOT_HALTED  0x79
#define P6_NMI_EVENT            P6_EVENT_CPU_CLOCKS_NOT_HALTED

#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)

#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

static int __init check_nmi_watchdog(void)
{
        volatile int endflag = 0;
        unsigned int *prev_nmi_count;
        int cpu;

        if (nmi_watchdog == NMI_NONE)
                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_cpu(cpu)
                prev_nmi_count[cpu] = per_cpu(irq_stat, cpu).__nmi_count;
        local_irq_enable();
        mdelay((10*1000)/nmi_hz); // wait 10 ticks

        for (cpu = 0; cpu < NR_CPUS; 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 (nmi_count(cpu) - prev_nmi_count[cpu] <= 5) {
                        endflag = 1;
                        printk("CPU#%d: NMI appears to be stuck (%d->%d)!\n",
                                cpu,
                                prev_nmi_count[cpu],
                                nmi_count(cpu));
                        nmi_active = 0;
                        lapic_nmi_owner &= ~LAPIC_NMI_WATCHDOG;
                        kfree(prev_nmi_count);
                        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(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)
                return 0;
        if (nmi == NMI_NONE)
                nmi_watchdog = nmi;
        /*
         * If any other x86 CPU has a local APIC, then
         * please test the NMI stuff there and send me the
         * missing bits. Right now Intel P6/P4 and AMD K7 only.
         */
        if ((nmi == NMI_LOCAL_APIC) &&
                        (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) &&
                        (boot_cpu_data.x86 == 6 || boot_cpu_data.x86 == 15))
                nmi_watchdog = nmi;
        if ((nmi == NMI_LOCAL_APIC) &&
                        (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
                        (boot_cpu_data.x86 == 6 || boot_cpu_data.x86 == 15))
                nmi_watchdog = nmi;
        /*
         * We can enable the IO-APIC watchdog
         * unconditionally.
         */
        if (nmi == NMI_IO_APIC) {
                nmi_active = 1;
                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:
                switch (boot_cpu_data.x86) {
                case 6:
                        if (boot_cpu_data.x86_model > 0xd)
                                break;

                        wrmsr(MSR_P6_EVNTSEL0, 0, 0);
                        break;
                case 15:
                        if (boot_cpu_data.x86_model > 0x4)
                                break;

                        wrmsr(MSR_P4_IQ_CCCR0, 0, 0);
                        wrmsr(MSR_P4_CRU_ESCR0, 0, 0);
                        break;
                }
                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;
                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;

        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;
        }
}

#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 inline void write_watchdog_counter(const char *descr)
{
        u64 count = (u64)cpu_khz * 1000;

        do_div(count, nmi_hz);
        if(descr)
                Dprintk("setting %s to -0x%08Lx\n", descr, count);
        wrmsrl(nmi_perfctr_msr, 0 - count);
}

static void setup_k7_watchdog(void)
{
        unsigned int evntsel;

        nmi_perfctr_msr = MSR_K7_PERFCTR0;

        clear_msr_range(MSR_K7_EVNTSEL0, 4);
        clear_msr_range(MSR_K7_PERFCTR0, 4);

        evntsel = K7_EVNTSEL_INT
                | K7_EVNTSEL_OS
                | K7_EVNTSEL_USR
                | K7_NMI_EVENT;

        wrmsr(MSR_K7_EVNTSEL0, evntsel, 0);
        write_watchdog_counter("K7_PERFCTR0");
        apic_write(APIC_LVTPC, APIC_DM_NMI);
        evntsel |= K7_EVNTSEL_ENABLE;
        wrmsr(MSR_K7_EVNTSEL0, evntsel, 0);
}

static void setup_p6_watchdog(void)
{
        unsigned int evntsel;

        nmi_perfctr_msr = MSR_P6_PERFCTR0;

        clear_msr_range(MSR_P6_EVNTSEL0, 2);
        clear_msr_range(MSR_P6_PERFCTR0, 2);

        evntsel = P6_EVNTSEL_INT
                | P6_EVNTSEL_OS
                | P6_EVNTSEL_USR
                | P6_NMI_EVENT;

        wrmsr(MSR_P6_EVNTSEL0, evntsel, 0);
        write_watchdog_counter("P6_PERFCTR0");
        apic_write(APIC_LVTPC, APIC_DM_NMI);
        evntsel |= P6_EVNTSEL0_ENABLE;
        wrmsr(MSR_P6_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);
        write_watchdog_counter("P4_IQ_COUNTER0");
        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 != 6 && boot_cpu_data.x86 != 15)
                        return;
                setup_k7_watchdog();
                break;
        case X86_VENDOR_INTEL:
                switch (boot_cpu_data.x86) {
                case 6:
                        if (boot_cpu_data.x86_model > 0xd)
                                return;

                        setup_p6_watchdog();
                        break;
                case 15:
                        if (boot_cpu_data.x86_model > 0x4)
                                return;

                        if (!setup_p4_watchdog())
                                return;
                        break;
                default:
                        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.
 *
 * 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)
{
        int i;

        /*
         * Just reset the alert counters, (other CPUs might be
         * spinning on locks we hold):
         */
        for (i = 0; i < NR_CPUS; i++)
                alert_counter[i] = 0;

        /*
         * Tickle the softlockup detector too:
         */
        touch_softlockup_watchdog();
}

extern void die_nmi(struct pt_regs *, const char *msg);

void nmi_watchdog_tick (struct pt_regs * regs)
{

        /*
         * 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().
         */
        int sum, cpu = smp_processor_id();

        sum = per_cpu(irq_stat, cpu).apic_timer_irqs;

        if (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, "NMI Watchdog detected LOCKUP");

                last_irq_sums[cpu] = sum;
                alert_counter[cpu] = 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);
                }
                else if (nmi_perfctr_msr == MSR_P6_PERFCTR0) {
                        /* Only P6 based Pentium M need to re-unmask
                         * the apic vector but it doesn't hurt
                         * other P6 variant */
                        apic_write(APIC_LVTPC, APIC_DM_NMI);
                }
                write_watchdog_counter(NULL);
        }
}

#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(regs, buf);
        }
        return 0;
}

/*
 * proc handler for /proc/sys/kernel/unknown_nmi_panic
 */
int proc_unknown_nmi_panic(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);