nmi.c

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/*
 *   Machine check handler
 *
 *    Copyright IBM Corp. 2000, 2009
 *    Author(s): Ingo Adlung <[email protected]>,
 *       Martin Schwidefsky <[email protected]>,
 *       Cornelia Huck <[email protected]>,
 *       Heiko Carstens <[email protected]>,
 */

#include <linux/kernel_stat.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/hardirq.h>
#include <linux/time.h>
#include <linux/module.h>
#include <asm/lowcore.h>
#include <asm/smp.h>
#include <asm/etr.h>
#include <asm/cputime.h>
#include <asm/nmi.h>
#include <asm/crw.h>

struct mcck_struct {
    int kill_task;
    int channel_report;
    int warning;
    unsigned long long mcck_code;
};

static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);

static void s390_handle_damage(char *msg)
{
    smp_send_stop();
    disabled_wait((unsigned long) __builtin_return_address(0));
    while (1);
}

/*
 * Main machine check handler function. Will be called with interrupts enabled
 * or disabled and machine checks enabled or disabled.
 */
void s390_handle_mcck(void)
{
    unsigned long flags;
    struct mcck_struct mcck;

    /*
     * Disable machine checks and get the current state of accumulated
     * machine checks. Afterwards delete the old state and enable machine
     * checks again.
     */
    local_irq_save(flags);
    local_mcck_disable();
    mcck = __get_cpu_var(cpu_mcck);
    memset(&__get_cpu_var(cpu_mcck), 0, sizeof(struct mcck_struct));
    clear_thread_flag(TIF_MCCK_PENDING);
    local_mcck_enable();
    local_irq_restore(flags);

    if (mcck.channel_report)
        crw_handle_channel_report();
    /*
     * A warning may remain for a prolonged period on the bare iron.
     * (actually until the machine is powered off, or the problem is gone)
     * So we just stop listening for the WARNING MCH and avoid continuously
     * being interrupted.  One caveat is however, that we must do this per
     * processor and cannot use the smp version of ctl_clear_bit().
     * On VM we only get one interrupt per virtally presented machinecheck.
     * Though one suffices, we may get one interrupt per (virtual) cpu.
     */
    if (mcck.warning) { /* WARNING pending ? */
        static int mchchk_wng_posted = 0;

        /* Use single cpu clear, as we cannot handle smp here. */
        __ctl_clear_bit(14, 24);    /* Disable WARNING MCH */
        if (xchg(&mchchk_wng_posted, 1) == 0)
            kill_cad_pid(SIGPWR, 1);
    }
    if (mcck.kill_task) {
        local_irq_enable();
        printk(KERN_EMERG "mcck: Terminating task because of machine "
               "malfunction (code 0x%016llx).\n", mcck.mcck_code);
        printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
               current->comm, current->pid);
        do_exit(SIGSEGV);
    }
}
EXPORT_SYMBOL_GPL(s390_handle_mcck);

/*
 * returns 0 if all registers could be validated
 * returns 1 otherwise
 */
static int notrace s390_revalidate_registers(struct mci *mci)
{
    int kill_task;
    u64 zero;
    void *fpt_save_area, *fpt_creg_save_area;

    kill_task = 0;
    zero = 0;

    if (!mci->gr) {
        /*
         * General purpose registers couldn't be restored and have
         * unknown contents. Process needs to be terminated.
         */
        kill_task = 1;
    }
    if (!mci->fp) {
        /*
         * Floating point registers can't be restored and
         * therefore the process needs to be terminated.
         */
        kill_task = 1;
    }
#ifndef CONFIG_64BIT
    asm volatile(
        "   ld  0,0(%0)\n"
        "   ld  2,8(%0)\n"
        "   ld  4,16(%0)\n"
        "   ld  6,24(%0)"
        : : "a" (&S390_lowcore.floating_pt_save_area));
#endif

    if (MACHINE_HAS_IEEE) {
#ifdef CONFIG_64BIT
        fpt_save_area = &S390_lowcore.floating_pt_save_area;
        fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
#else
        fpt_save_area = (void *) S390_lowcore.extended_save_area_addr;
        fpt_creg_save_area = fpt_save_area + 128;
#endif
        if (!mci->fc) {
            /*
             * Floating point control register can't be restored.
             * Task will be terminated.
             */
            asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
            kill_task = 1;

        } else
            asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));

        asm volatile(
            "   ld  0,0(%0)\n"
            "   ld  1,8(%0)\n"
            "   ld  2,16(%0)\n"
            "   ld  3,24(%0)\n"
            "   ld  4,32(%0)\n"
            "   ld  5,40(%0)\n"
            "   ld  6,48(%0)\n"
            "   ld  7,56(%0)\n"
            "   ld  8,64(%0)\n"
            "   ld  9,72(%0)\n"
            "   ld  10,80(%0)\n"
            "   ld  11,88(%0)\n"
            "   ld  12,96(%0)\n"
            "   ld  13,104(%0)\n"
            "   ld  14,112(%0)\n"
            "   ld  15,120(%0)\n"
            : : "a" (fpt_save_area));
    }
    /* Revalidate access registers */
    asm volatile(
        "   lam 0,15,0(%0)"
        : : "a" (&S390_lowcore.access_regs_save_area));
    if (!mci->ar) {
        /*
         * Access registers have unknown contents.
         * Terminating task.
         */
        kill_task = 1;
    }
    /* Revalidate control registers */
    if (!mci->cr) {
        /*
         * Control registers have unknown contents.
         * Can't recover and therefore stopping machine.
         */
        s390_handle_damage("invalid control registers.");
    } else {
#ifdef CONFIG_64BIT
        asm volatile(
            "   lctlg   0,15,0(%0)"
            : : "a" (&S390_lowcore.cregs_save_area));
#else
        asm volatile(
            "   lctl    0,15,0(%0)"
            : : "a" (&S390_lowcore.cregs_save_area));
#endif
    }
    /*
     * We don't even try to revalidate the TOD register, since we simply
     * can't write something sensible into that register.
     */
#ifdef CONFIG_64BIT
    /*
     * See if we can revalidate the TOD programmable register with its
     * old contents (should be zero) otherwise set it to zero.
     */
    if (!mci->pr)
        asm volatile(
            "   sr  0,0\n"
            "   sckpf"
            : : : "0", "cc");
    else
        asm volatile(
            "   l   0,0(%0)\n"
            "   sckpf"
            : : "a" (&S390_lowcore.tod_progreg_save_area)
            : "0", "cc");
#endif
    /* Revalidate clock comparator register */
    if (S390_lowcore.clock_comparator == -1)
        set_clock_comparator(S390_lowcore.mcck_clock);
    else
        set_clock_comparator(S390_lowcore.clock_comparator);
    /* Check if old PSW is valid */
    if (!mci->wp)
        /*
         * Can't tell if we come from user or kernel mode
         * -> stopping machine.
         */
        s390_handle_damage("old psw invalid.");

    if (!mci->ms || !mci->pm || !mci->ia)
        kill_task = 1;

    return kill_task;
}

#define MAX_IPD_COUNT   29
#define MAX_IPD_TIME    (5 * 60 * USEC_PER_SEC) /* 5 minutes */

#define ED_STP_ISLAND   6   /* External damage STP island check */
#define ED_STP_SYNC 7   /* External damage STP sync check */
#define ED_ETR_SYNC 12  /* External damage ETR sync check */
#define ED_ETR_SWITCH   13  /* External damage ETR switch to local */

/*
 * machine check handler.
 */
void notrace s390_do_machine_check(struct pt_regs *regs)
{
    static int ipd_count;
    static DEFINE_SPINLOCK(ipd_lock);
    static unsigned long long last_ipd;
    struct mcck_struct *mcck;
    unsigned long long tmp;
    struct mci *mci;
    int umode;

    nmi_enter();
    kstat_cpu(smp_processor_id()).irqs[NMI_NMI]++;
    mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
    mcck = &__get_cpu_var(cpu_mcck);
    umode = user_mode(regs);

    if (mci->sd) {
        /* System damage -> stopping machine */
        s390_handle_damage("received system damage machine check.");
    }
    if (mci->pd) {
        if (mci->b) {
            /* Processing backup -> verify if we can survive this */
            u64 z_mcic, o_mcic, t_mcic;
#ifdef CONFIG_64BIT
            z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
            o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
                  1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
                  1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
                  1ULL<<16);
#else
            z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<57 | 1ULL<<50 |
                  1ULL<<29);
            o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
                  1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
                  1ULL<<30 | 1ULL<<20 | 1ULL<<17 | 1ULL<<16);
#endif
            t_mcic = *(u64 *)mci;

            if (((t_mcic & z_mcic) != 0) ||
                ((t_mcic & o_mcic) != o_mcic)) {
                s390_handle_damage("processing backup machine "
                           "check with damage.");
            }

            /*
             * Nullifying exigent condition, therefore we might
             * retry this instruction.
             */
            spin_lock(&ipd_lock);
            tmp = get_clock();
            if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
                ipd_count++;
            else
                ipd_count = 1;
            last_ipd = tmp;
            if (ipd_count == MAX_IPD_COUNT)
                s390_handle_damage("too many ipd retries.");
            spin_unlock(&ipd_lock);
        } else {
            /* Processing damage -> stopping machine */
            s390_handle_damage("received instruction processing "
                       "damage machine check.");
        }
    }
    if (s390_revalidate_registers(mci)) {
        if (umode) {
            /*
             * Couldn't restore all register contents while in
             * user mode -> mark task for termination.
             */
            mcck->kill_task = 1;
            mcck->mcck_code = *(unsigned long long *) mci;
            set_thread_flag(TIF_MCCK_PENDING);
        } else {
            /*
             * Couldn't restore all register contents while in
             * kernel mode -> stopping machine.
             */
            s390_handle_damage("unable to revalidate registers.");
        }
    }
    if (mci->cd) {
        /* Timing facility damage */
        s390_handle_damage("TOD clock damaged");
    }
    if (mci->ed && mci->ec) {
        /* External damage */
        if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
            etr_sync_check();
        if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
            etr_switch_to_local();
        if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
            stp_sync_check();
        if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
            stp_island_check();
    }
    if (mci->se)
        /* Storage error uncorrected */
        s390_handle_damage("received storage error uncorrected "
                   "machine check.");
    if (mci->ke)
        /* Storage key-error uncorrected */
        s390_handle_damage("received storage key-error uncorrected "
                   "machine check.");
    if (mci->ds && mci->fa)
        /* Storage degradation */
        s390_handle_damage("received storage degradation machine "
                   "check.");
    if (mci->cp) {
        /* Channel report word pending */
        mcck->channel_report = 1;
        set_thread_flag(TIF_MCCK_PENDING);
    }
    if (mci->w) {
        /* Warning pending */
        mcck->warning = 1;
        set_thread_flag(TIF_MCCK_PENDING);
    }
    nmi_exit();
}

static int __init machine_check_init(void)
{
    ctl_set_bit(14, 25);    /* enable external damage MCH */
    ctl_set_bit(14, 27);    /* enable system recovery MCH */
    ctl_set_bit(14, 24);    /* enable warning MCH */
    return 0;
}
arch_initcall(machine_check_init);