platform.c

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/*
 * Persistent Storage - platform driver interface parts.
 *
 * Copyright (C) 2007-2008 Google, Inc.
 * Copyright (C) 2010 Intel Corporation <[email protected]>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  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/atomic.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kmsg_dump.h>
#include <linux/console.h>
#include <linux/module.h>
#include <linux/pstore.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/jiffies.h>
#include <linux/workqueue.h>

#include "internal.h"

/*
 * We defer making "oops" entries appear in pstore - see
 * whether the system is actually still running well enough
 * to let someone see the entry
 */
static int pstore_update_ms = -1;
module_param_named(update_ms, pstore_update_ms, int, 0600);
MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
         "(default is -1, which means runtime updates are disabled; "
         "enabling this option is not safe, it may lead to further "
         "corruption on Oopses)");

static int pstore_new_entry;

static void pstore_timefunc(unsigned long);
static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);

static void pstore_dowork(struct work_struct *);
static DECLARE_WORK(pstore_work, pstore_dowork);

/*
 * pstore_lock just protects "psinfo" during
 * calls to pstore_register()
 */
static DEFINE_SPINLOCK(pstore_lock);
struct pstore_info *psinfo;

static char *backend;

/* How much of the console log to snapshot */
static unsigned long kmsg_bytes = 10240;

void pstore_set_kmsg_bytes(int bytes)
{
    kmsg_bytes = bytes;
}

/* Tag each group of saved records with a sequence number */
static int  oopscount;

static const char *get_reason_str(enum kmsg_dump_reason reason)
{
    switch (reason) {
    case KMSG_DUMP_PANIC:
        return "Panic";
    case KMSG_DUMP_OOPS:
        return "Oops";
    case KMSG_DUMP_EMERG:
        return "Emergency";
    case KMSG_DUMP_RESTART:
        return "Restart";
    case KMSG_DUMP_HALT:
        return "Halt";
    case KMSG_DUMP_POWEROFF:
        return "Poweroff";
    default:
        return "Unknown";
    }
}

/*
 * callback from kmsg_dump. (s2,l2) has the most recently
 * written bytes, older bytes are in (s1,l1). Save as much
 * as we can from the end of the buffer.
 */
static void pstore_dump(struct kmsg_dumper *dumper,
            enum kmsg_dump_reason reason)
{
    unsigned long   total = 0;
    const char  *why;
    u64     id;
    unsigned int    part = 1;
    unsigned long   flags = 0;
    int     is_locked = 0;
    int     ret;

    why = get_reason_str(reason);

    if (in_nmi()) {
        is_locked = spin_trylock(&psinfo->buf_lock);
        if (!is_locked)
            pr_err("pstore dump routine blocked in NMI, may corrupt error record\n");
    } else
        spin_lock_irqsave(&psinfo->buf_lock, flags);
    oopscount++;
    while (total < kmsg_bytes) {
        char *dst;
        unsigned long size;
        int hsize;
        size_t len;

        dst = psinfo->buf;
        hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
        size = psinfo->bufsize - hsize;
        dst += hsize;

        if (!kmsg_dump_get_buffer(dumper, true, dst, size, &len))
            break;

        ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
                    hsize + len, psinfo);
        if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
            pstore_new_entry = 1;

        total += hsize + len;
        part++;
    }
    if (in_nmi()) {
        if (is_locked)
            spin_unlock(&psinfo->buf_lock);
    } else
        spin_unlock_irqrestore(&psinfo->buf_lock, flags);
}

static struct kmsg_dumper pstore_dumper = {
    .dump = pstore_dump,
};

#ifdef CONFIG_PSTORE_CONSOLE
static void pstore_console_write(struct console *con, const char *s, unsigned c)
{
    const char *e = s + c;

    while (s < e) {
        unsigned long flags;
        u64 id;

        if (c > psinfo->bufsize)
            c = psinfo->bufsize;

        if (oops_in_progress) {
            if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
                break;
        } else {
            spin_lock_irqsave(&psinfo->buf_lock, flags);
        }
        memcpy(psinfo->buf, s, c);
        psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, c, psinfo);
        spin_unlock_irqrestore(&psinfo->buf_lock, flags);
        s += c;
        c = e - s;
    }
}

static struct console pstore_console = {
    .name   = "pstore",
    .write  = pstore_console_write,
    .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
    .index  = -1,
};

static void pstore_register_console(void)
{
    register_console(&pstore_console);
}
#else
static void pstore_register_console(void) {}
#endif

static int pstore_write_compat(enum pstore_type_id type,
                   enum kmsg_dump_reason reason,
                   u64 *id, unsigned int part,
                   size_t size, struct pstore_info *psi)
{
    return psi->write_buf(type, reason, id, part, psinfo->buf, size, psi);
}

/*
 * platform specific persistent storage driver registers with
 * us here. If pstore is already mounted, call the platform
 * read function right away to populate the file system. If not
 * then the pstore mount code will call us later to fill out
 * the file system.
 *
 * Register with kmsg_dump to save last part of console log on panic.
 */
int pstore_register(struct pstore_info *psi)
{
    struct module *owner = psi->owner;

    spin_lock(&pstore_lock);
    if (psinfo) {
        spin_unlock(&pstore_lock);
        return -EBUSY;
    }

    if (backend && strcmp(backend, psi->name)) {
        spin_unlock(&pstore_lock);
        return -EINVAL;
    }

    if (!psi->write)
        psi->write = pstore_write_compat;
    psinfo = psi;
    mutex_init(&psinfo->read_mutex);
    spin_unlock(&pstore_lock);

    if (owner && !try_module_get(owner)) {
        psinfo = NULL;
        return -EINVAL;
    }

    if (pstore_is_mounted())
        pstore_get_records(0);

    kmsg_dump_register(&pstore_dumper);
    pstore_register_console();
    pstore_register_ftrace();

    if (pstore_update_ms >= 0) {
        pstore_timer.expires = jiffies +
            msecs_to_jiffies(pstore_update_ms);
        add_timer(&pstore_timer);
    }

    return 0;
}
EXPORT_SYMBOL_GPL(pstore_register);

/*
 * Read all the records from the persistent store. Create
 * files in our filesystem.  Don't warn about -EEXIST errors
 * when we are re-scanning the backing store looking to add new
 * error records.
 */
void pstore_get_records(int quiet)
{
    struct pstore_info *psi = psinfo;
    char            *buf = NULL;
    ssize_t         size;
    u64         id;
    enum pstore_type_id type;
    struct timespec     time;
    int         failed = 0, rc;

    if (!psi)
        return;

    mutex_lock(&psi->read_mutex);
    if (psi->open && psi->open(psi))
        goto out;

    while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
        rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size,
                  time, psi);
        kfree(buf);
        buf = NULL;
        if (rc && (rc != -EEXIST || !quiet))
            failed++;
    }
    if (psi->close)
        psi->close(psi);
out:
    mutex_unlock(&psi->read_mutex);

    if (failed)
        printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
               failed, psi->name);
}

static void pstore_dowork(struct work_struct *work)
{
    pstore_get_records(1);
}

static void pstore_timefunc(unsigned long dummy)
{
    if (pstore_new_entry) {
        pstore_new_entry = 0;
        schedule_work(&pstore_work);
    }

    mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
}

module_param(backend, charp, 0444);
MODULE_PARM_DESC(backend, "Pstore backend to use");