fs/pstore/platform.c

   1 /*
   2  * Persistent Storage - platform driver interface parts.
   3  *
   4  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License version 2 as
   8  *  published by the Free Software Foundation.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19
  20 #include <linux/atomic.h>
  21 #include <linux/types.h>
  22 #include <linux/errno.h>
  23 #include <linux/init.h>
  24 #include <linux/kmsg_dump.h>
  25 #include <linux/module.h>
  26 #include <linux/pstore.h>
  27 #include <linux/string.h>
  28 #include <linux/timer.h>
  29 #include <linux/slab.h>
  30 #include <linux/uaccess.h>
  31 #include <linux/hardirq.h>
  32 #include <linux/workqueue.h>
  33
  34 #include "internal.h"
  35
  36 /*
  37  * We defer making "oops" entries appear in pstore - see
  38  * whether the system is actually still running well enough
  39  * to let someone see the entry
  40  */
  41 #define PSTORE_INTERVAL (60 * HZ)
  42
  43 static int pstore_new_entry;
  44
  45 static void pstore_timefunc(unsigned long);
  46 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
  47
  48 static void pstore_dowork(struct work_struct *);
  49 static DECLARE_WORK(pstore_work, pstore_dowork);
  50
  51 /*
  52  * pstore_lock just protects "psinfo" during
  53  * calls to pstore_register()
  54  */
  55 static DEFINE_SPINLOCK(pstore_lock);
  56 static struct pstore_info *psinfo;
  57
  58 static char *backend;
  59
  60 /* How much of the console log to snapshot */
  61 static unsigned long kmsg_bytes = 10240;
  62
  63 void pstore_set_kmsg_bytes(int bytes)
  64 {
  65         kmsg_bytes = bytes;
  66 }
  67
  68 /* Tag each group of saved records with a sequence number */
  69 static int      oopscount;
  70
  71 static const char *get_reason_str(enum kmsg_dump_reason reason)
  72 {
  73         switch (reason) {
  74         case KMSG_DUMP_PANIC:
  75                 return "Panic";
  76         case KMSG_DUMP_OOPS:
  77                 return "Oops";
  78         case KMSG_DUMP_EMERG:
  79                 return "Emergency";
  80         case KMSG_DUMP_RESTART:
  81                 return "Restart";
  82         case KMSG_DUMP_HALT:
  83                 return "Halt";
  84         case KMSG_DUMP_POWEROFF:
  85                 return "Poweroff";
  86         default:
  87                 return "Unknown";
  88         }
  89 }
  90
  91 /*
  92  * callback from kmsg_dump. (s2,l2) has the most recently
  93  * written bytes, older bytes are in (s1,l1). Save as much
  94  * as we can from the end of the buffer.
  95  */
  96 static void pstore_dump(struct kmsg_dumper *dumper,
  97                         enum kmsg_dump_reason reason)
  98 {
  99         unsigned long   total = 0;
 100         const char      *why;
 101         u64             id;
 102         unsigned int    part = 1;
 103         unsigned long   flags = 0;
 104         int             is_locked = 0;
 105         int             ret;
 106
 107         why = get_reason_str(reason);
 108
 109         if (in_nmi()) {
 110                 is_locked = spin_trylock(&psinfo->buf_lock);
 111                 if (!is_locked)
 112                         pr_err("pstore dump routine blocked in NMI, may corrupt error record\n");
 113         } else
 114                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 115         oopscount++;
 116         while (total < kmsg_bytes) {
 117                 char *dst;
 118                 unsigned long size;
 119                 int hsize;
 120                 size_t len;
 121
 122                 dst = psinfo->buf;
 123                 hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
 124                 size = psinfo->bufsize - hsize;
 125                 dst += hsize;
 126
 127                 if (!kmsg_dump_get_buffer(dumper, true, dst, size, &len))
 128                         break;
 129
 130                 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
 131                                     hsize + len, psinfo);
 132                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 133                         pstore_new_entry = 1;
 134
 135                 total += hsize + len;
 136                 part++;
 137         }
 138         if (in_nmi()) {
 139                 if (is_locked)
 140                         spin_unlock(&psinfo->buf_lock);
 141         } else
 142                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 143 }
 144
 145 static struct kmsg_dumper pstore_dumper = {
 146         .dump = pstore_dump,
 147 };
 148
 149 /*
 150  * platform specific persistent storage driver registers with
 151  * us here. If pstore is already mounted, call the platform
 152  * read function right away to populate the file system. If not
 153  * then the pstore mount code will call us later to fill out
 154  * the file system.
 155  *
 156  * Register with kmsg_dump to save last part of console log on panic.
 157  */
 158 int pstore_register(struct pstore_info *psi)
 159 {
 160         struct module *owner = psi->owner;
 161
 162         spin_lock(&pstore_lock);
 163         if (psinfo) {
 164                 spin_unlock(&pstore_lock);
 165                 return -EBUSY;
 166         }
 167
 168         if (backend && strcmp(backend, psi->name)) {
 169                 spin_unlock(&pstore_lock);
 170                 return -EINVAL;
 171         }
 172
 173         psinfo = psi;
 174         mutex_init(&psinfo->read_mutex);
 175         spin_unlock(&pstore_lock);
 176
 177         if (owner && !try_module_get(owner)) {
 178                 psinfo = NULL;
 179                 return -EINVAL;
 180         }
 181
 182         if (pstore_is_mounted())
 183                 pstore_get_records(0);
 184
 185         kmsg_dump_register(&pstore_dumper);
 186
 187         pstore_timer.expires = jiffies + PSTORE_INTERVAL;
 188         add_timer(&pstore_timer);
 189
 190         return 0;
 191 }
 192 EXPORT_SYMBOL_GPL(pstore_register);
 193
 194 /*
 195  * Read all the records from the persistent store. Create
 196  * files in our filesystem.  Don't warn about -EEXIST errors
 197  * when we are re-scanning the backing store looking to add new
 198  * error records.
 199  */
 200 void pstore_get_records(int quiet)
 201 {
 202         struct pstore_info *psi = psinfo;
 203         char                    *buf = NULL;
 204         ssize_t                 size;
 205         u64                     id;
 206         enum pstore_type_id     type;
 207         struct timespec         time;
 208         int                     failed = 0, rc;
 209
 210         if (!psi)
 211                 return;
 212
 213         mutex_lock(&psi->read_mutex);
 214         if (psi->open && psi->open(psi))
 215                 goto out;
 216
 217         while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
 218                 rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size,
 219                                   time, psi);
 220                 kfree(buf);
 221                 buf = NULL;
 222                 if (rc && (rc != -EEXIST || !quiet))
 223                         failed++;
 224         }
 225         if (psi->close)
 226                 psi->close(psi);
 227 out:
 228         mutex_unlock(&psi->read_mutex);
 229
 230         if (failed)
 231                 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
 232                        failed, psi->name);
 233 }
 234
 235 static void pstore_dowork(struct work_struct *work)
 236 {
 237         pstore_get_records(1);
 238 }
 239
 240 static void pstore_timefunc(unsigned long dummy)
 241 {
 242         if (pstore_new_entry) {
 243                 pstore_new_entry = 0;
 244                 schedule_work(&pstore_work);
 245         }
 246
 247         mod_timer(&pstore_timer, jiffies + PSTORE_INTERVAL);
 248 }
 249
 250 module_param(backend, charp, 0444);
 251 MODULE_PARM_DESC(backend, "Pstore backend to use");