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- /*
- * Persistent Storage - platform driver interface parts.
- *
- * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
- *
- * 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/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/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
- */
- #define PSTORE_INTERVAL (60 * HZ)
- 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);
- static 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";
- }
- }
- bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
- {
- /*
- * In case of NMI path, pstore shouldn't be blocked
- * regardless of reason.
- */
- if (in_nmi())
- return true;
- switch (reason) {
- /* In panic case, other cpus are stopped by smp_send_stop(). */
- case KMSG_DUMP_PANIC:
- /* Emergency restart shouldn't be blocked by spin lock. */
- case KMSG_DUMP_EMERG:
- return true;
- default:
- return false;
- }
- }
- EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
- /*
- * 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,
- const char *s1, unsigned long l1,
- const char *s2, unsigned long l2)
- {
- unsigned long s1_start, s2_start;
- unsigned long l1_cpy, l2_cpy;
- unsigned long size, total = 0;
- char *dst;
- const char *why;
- u64 id;
- int hsize, ret;
- unsigned int part = 1;
- unsigned long flags = 0;
- int is_locked = 0;
- why = get_reason_str(reason);
- if (pstore_cannot_block_path(reason)) {
- is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
- if (!is_locked) {
- pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
- , in_nmi() ? "NMI" : why);
- }
- } else
- spin_lock_irqsave(&psinfo->buf_lock, flags);
- oopscount++;
- while (total < kmsg_bytes) {
- dst = psinfo->buf;
- hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
- size = psinfo->bufsize - hsize;
- dst += hsize;
- l2_cpy = min(l2, size);
- l1_cpy = min(l1, size - l2_cpy);
- if (l1_cpy + l2_cpy == 0)
- break;
- s2_start = l2 - l2_cpy;
- s1_start = l1 - l1_cpy;
- memcpy(dst, s1 + s1_start, l1_cpy);
- memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
- ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
- hsize + l1_cpy + l2_cpy, psinfo);
- if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
- pstore_new_entry = 1;
- l1 -= l1_cpy;
- l2 -= l2_cpy;
- total += l1_cpy + l2_cpy;
- part++;
- }
- if (pstore_cannot_block_path(reason)) {
- if (is_locked)
- spin_unlock_irqrestore(&psinfo->buf_lock, flags);
- } else
- spin_unlock_irqrestore(&psinfo->buf_lock, flags);
- }
- static struct kmsg_dumper pstore_dumper = {
- .dump = pstore_dump,
- };
- /*
- * 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;
- }
- 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_timer.expires = jiffies + PSTORE_INTERVAL;
- 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 + PSTORE_INTERVAL);
- }
- module_param(backend, charp, 0444);
- MODULE_PARM_DESC(backend, "Pstore backend to use");
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