ras.c

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/*
 * Copyright (C) 2001 Dave Engebretsen IBM Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/of.h>
#include <linux/fs.h>
#include <linux/reboot.h>

#include <asm/machdep.h>
#include <asm/rtas.h>
#include <asm/firmware.h>

#include "pseries.h"

static unsigned char ras_log_buf[RTAS_ERROR_LOG_MAX];
static DEFINE_SPINLOCK(ras_log_buf_lock);

static char global_mce_data_buf[RTAS_ERROR_LOG_MAX];
static DEFINE_PER_CPU(__u64, mce_data_buf);

static int ras_check_exception_token;

#define EPOW_SENSOR_TOKEN   9
#define EPOW_SENSOR_INDEX   0

static irqreturn_t ras_epow_interrupt(int irq, void *dev_id);
static irqreturn_t ras_error_interrupt(int irq, void *dev_id);


/*
 * Initialize handlers for the set of interrupts caused by hardware errors
 * and power system events.
 */
static int __init init_ras_IRQ(void)
{
    struct device_node *np;

    ras_check_exception_token = rtas_token("check-exception");

    /* Internal Errors */
    np = of_find_node_by_path("/event-sources/internal-errors");
    if (np != NULL) {
        request_event_sources_irqs(np, ras_error_interrupt,
                       "RAS_ERROR");
        of_node_put(np);
    }

    /* EPOW Events */
    np = of_find_node_by_path("/event-sources/epow-events");
    if (np != NULL) {
        request_event_sources_irqs(np, ras_epow_interrupt, "RAS_EPOW");
        of_node_put(np);
    }

    return 0;
}
subsys_initcall(init_ras_IRQ);

#define EPOW_SHUTDOWN_NORMAL                1
#define EPOW_SHUTDOWN_ON_UPS                2
#define EPOW_SHUTDOWN_LOSS_OF_CRITICAL_FUNCTIONS    3
#define EPOW_SHUTDOWN_AMBIENT_TEMPERATURE_TOO_HIGH  4

static void handle_system_shutdown(char event_modifier)
{
    switch (event_modifier) {
    case EPOW_SHUTDOWN_NORMAL:
        pr_emerg("Firmware initiated power off");
        orderly_poweroff(1);
        break;

    case EPOW_SHUTDOWN_ON_UPS:
        pr_emerg("Loss of power reported by firmware, system is "
            "running on UPS/battery");
        break;

    case EPOW_SHUTDOWN_LOSS_OF_CRITICAL_FUNCTIONS:
        pr_emerg("Loss of system critical functions reported by "
            "firmware");
        pr_emerg("Check RTAS error log for details");
        orderly_poweroff(1);
        break;

    case EPOW_SHUTDOWN_AMBIENT_TEMPERATURE_TOO_HIGH:
        pr_emerg("Ambient temperature too high reported by firmware");
        pr_emerg("Check RTAS error log for details");
        orderly_poweroff(1);
        break;

    default:
        pr_err("Unknown power/cooling shutdown event (modifier %d)",
            event_modifier);
    }
}

struct epow_errorlog {
    unsigned char sensor_value;
    unsigned char event_modifier;
    unsigned char extended_modifier;
    unsigned char reserved;
    unsigned char platform_reason;
};

#define EPOW_RESET          0
#define EPOW_WARN_COOLING       1
#define EPOW_WARN_POWER         2
#define EPOW_SYSTEM_SHUTDOWN        3
#define EPOW_SYSTEM_HALT        4
#define EPOW_MAIN_ENCLOSURE     5
#define EPOW_POWER_OFF          7

void rtas_parse_epow_errlog(struct rtas_error_log *log)
{
    struct pseries_errorlog *pseries_log;
    struct epow_errorlog *epow_log;
    char action_code;
    char modifier;

    pseries_log = get_pseries_errorlog(log, PSERIES_ELOG_SECT_ID_EPOW);
    if (pseries_log == NULL)
        return;

    epow_log = (struct epow_errorlog *)pseries_log->data;
    action_code = epow_log->sensor_value & 0xF; /* bottom 4 bits */
    modifier = epow_log->event_modifier & 0xF;  /* bottom 4 bits */

    switch (action_code) {
    case EPOW_RESET:
        pr_err("Non critical power or cooling issue cleared");
        break;

    case EPOW_WARN_COOLING:
        pr_err("Non critical cooling issue reported by firmware");
        pr_err("Check RTAS error log for details");
        break;

    case EPOW_WARN_POWER:
        pr_err("Non critical power issue reported by firmware");
        pr_err("Check RTAS error log for details");
        break;

    case EPOW_SYSTEM_SHUTDOWN:
        handle_system_shutdown(epow_log->event_modifier);
        break;

    case EPOW_SYSTEM_HALT:
        pr_emerg("Firmware initiated power off");
        orderly_poweroff(1);
        break;

    case EPOW_MAIN_ENCLOSURE:
    case EPOW_POWER_OFF:
        pr_emerg("Critical power/cooling issue reported by firmware");
        pr_emerg("Check RTAS error log for details");
        pr_emerg("Immediate power off");
        emergency_sync();
        kernel_power_off();
        break;

    default:
        pr_err("Unknown power/cooling event (action code %d)",
            action_code);
    }
}

/* Handle environmental and power warning (EPOW) interrupts. */
static irqreturn_t ras_epow_interrupt(int irq, void *dev_id)
{
    int status;
    int state;
    int critical;

    status = rtas_get_sensor(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, &state);

    if (state > 3)
        critical = 1;       /* Time Critical */
    else
        critical = 0;

    spin_lock(&ras_log_buf_lock);

    status = rtas_call(ras_check_exception_token, 6, 1, NULL,
               RTAS_VECTOR_EXTERNAL_INTERRUPT,
               virq_to_hw(irq),
               RTAS_EPOW_WARNING,
               critical, __pa(&ras_log_buf),
                rtas_get_error_log_max());

    log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, 0);

    rtas_parse_epow_errlog((struct rtas_error_log *)ras_log_buf);

    spin_unlock(&ras_log_buf_lock);
    return IRQ_HANDLED;
}

/*
 * Handle hardware error interrupts.
 *
 * RTAS check-exception is called to collect data on the exception.  If
 * the error is deemed recoverable, we log a warning and return.
 * For nonrecoverable errors, an error is logged and we stop all processing
 * as quickly as possible in order to prevent propagation of the failure.
 */
static irqreturn_t ras_error_interrupt(int irq, void *dev_id)
{
    struct rtas_error_log *rtas_elog;
    int status;
    int fatal;

    spin_lock(&ras_log_buf_lock);

    status = rtas_call(ras_check_exception_token, 6, 1, NULL,
               RTAS_VECTOR_EXTERNAL_INTERRUPT,
               virq_to_hw(irq),
               RTAS_INTERNAL_ERROR, 1 /* Time Critical */,
               __pa(&ras_log_buf),
                rtas_get_error_log_max());

    rtas_elog = (struct rtas_error_log *)ras_log_buf;

    if ((status == 0) && (rtas_elog->severity >= RTAS_SEVERITY_ERROR_SYNC))
        fatal = 1;
    else
        fatal = 0;

    /* format and print the extended information */
    log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, fatal);

    if (fatal) {
        pr_emerg("Fatal hardware error reported by firmware");
        pr_emerg("Check RTAS error log for details");
        pr_emerg("Immediate power off");
        emergency_sync();
        kernel_power_off();
    } else {
        pr_err("Recoverable hardware error reported by firmware");
    }

    spin_unlock(&ras_log_buf_lock);
    return IRQ_HANDLED;
}

/*
 * Some versions of FWNMI place the buffer inside the 4kB page starting at
 * 0x7000. Other versions place it inside the rtas buffer. We check both.
 */
#define VALID_FWNMI_BUFFER(A) \
    ((((A) >= 0x7000) && ((A) < 0x7ff0)) || \
    (((A) >= rtas.base) && ((A) < (rtas.base + rtas.size - 16))))

/*
 * Get the error information for errors coming through the
 * FWNMI vectors.  The pt_regs' r3 will be updated to reflect
 * the actual r3 if possible, and a ptr to the error log entry
 * will be returned if found.
 *
 * If the RTAS error is not of the extended type, then we put it in a per
 * cpu 64bit buffer. If it is the extended type we use global_mce_data_buf.
 *
 * The global_mce_data_buf does not have any locks or protection around it,
 * if a second machine check comes in, or a system reset is done
 * before we have logged the error, then we will get corruption in the
 * error log.  This is preferable over holding off on calling
 * ibm,nmi-interlock which would result in us checkstopping if a
 * second machine check did come in.
 */
static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
{
    unsigned long *savep;
    struct rtas_error_log *h, *errhdr = NULL;

    if (!VALID_FWNMI_BUFFER(regs->gpr[3])) {
        printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
        return NULL;
    }

    savep = __va(regs->gpr[3]);
    regs->gpr[3] = savep[0];    /* restore original r3 */

    /* If it isn't an extended log we can use the per cpu 64bit buffer */
    h = (struct rtas_error_log *)&savep[1];
    if (!h->extended) {
        memcpy(&__get_cpu_var(mce_data_buf), h, sizeof(__u64));
        errhdr = (struct rtas_error_log *)&__get_cpu_var(mce_data_buf);
    } else {
        int len;

        len = max_t(int, 8+h->extended_log_length, RTAS_ERROR_LOG_MAX);
        memset(global_mce_data_buf, 0, RTAS_ERROR_LOG_MAX);
        memcpy(global_mce_data_buf, h, len);
        errhdr = (struct rtas_error_log *)global_mce_data_buf;
    }

    return errhdr;
}

/* Call this when done with the data returned by FWNMI_get_errinfo.
 * It will release the saved data area for other CPUs in the
 * partition to receive FWNMI errors.
 */
static void fwnmi_release_errinfo(void)
{
    int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
    if (ret != 0)
        printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
}

int pSeries_system_reset_exception(struct pt_regs *regs)
{
    if (fwnmi_active) {
        struct rtas_error_log *errhdr = fwnmi_get_errinfo(regs);
        if (errhdr) {
            /* XXX Should look at FWNMI information */
        }
        fwnmi_release_errinfo();
    }
    return 0; /* need to perform reset */
}

/*
 * See if we can recover from a machine check exception.
 * This is only called on power4 (or above) and only via
 * the Firmware Non-Maskable Interrupts (fwnmi) handler
 * which provides the error analysis for us.
 *
 * Return 1 if corrected (or delivered a signal).
 * Return 0 if there is nothing we can do.
 */
static int recover_mce(struct pt_regs *regs, struct rtas_error_log *err)
{
    int recovered = 0;

    if (!(regs->msr & MSR_RI)) {
        /* If MSR_RI isn't set, we cannot recover */
        recovered = 0;

    } else if (err->disposition == RTAS_DISP_FULLY_RECOVERED) {
        /* Platform corrected itself */
        recovered = 1;

    } else if (err->disposition == RTAS_DISP_LIMITED_RECOVERY) {
        /* Platform corrected itself but could be degraded */
        printk(KERN_ERR "MCE: limited recovery, system may "
               "be degraded\n");
        recovered = 1;

    } else if (user_mode(regs) && !is_global_init(current) &&
           err->severity == RTAS_SEVERITY_ERROR_SYNC) {

        /*
         * If we received a synchronous error when in userspace
         * kill the task. Firmware may report details of the fail
         * asynchronously, so we can't rely on the target and type
         * fields being valid here.
         */
        printk(KERN_ERR "MCE: uncorrectable error, killing task "
               "%s:%d\n", current->comm, current->pid);

        _exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);
        recovered = 1;
    }

    log_error((char *)err, ERR_TYPE_RTAS_LOG, 0);

    return recovered;
}

/*
 * Handle a machine check.
 *
 * Note that on Power 4 and beyond Firmware Non-Maskable Interrupts (fwnmi)
 * should be present.  If so the handler which called us tells us if the
 * error was recovered (never true if RI=0).
 *
 * On hardware prior to Power 4 these exceptions were asynchronous which
 * means we can't tell exactly where it occurred and so we can't recover.
 */
int pSeries_machine_check_exception(struct pt_regs *regs)
{
    struct rtas_error_log *errp;

    if (fwnmi_active) {
        errp = fwnmi_get_errinfo(regs);
        fwnmi_release_errinfo();
        if (errp && recover_mce(regs, errp))
            return 1;
    }

    return 0;
}