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             const char *s1, unsigned long l1,
  99             const char *s2, unsigned long l2)
 100 {
 101         unsigned long   s1_start, s2_start;
 102         unsigned long   l1_cpy, l2_cpy;
 103         unsigned long   size, total = 0;
 104         char            *dst;
 105         const char      *why;
 106         u64             id;
 107         int             hsize, ret;
 108         unsigned int    part = 1;
 109         unsigned long   flags = 0;
 110         int             is_locked = 0;
 111
 112         why = get_reason_str(reason);
 113
 114         if (in_nmi()) {
 115                 is_locked = spin_trylock(&psinfo->buf_lock);
 116                 if (!is_locked)
 117                         pr_err("pstore dump routine blocked in NMI, may corrupt error record\n");
 118         } else
 119                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 120         oopscount++;
 121         while (total < kmsg_bytes) {
 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                 l2_cpy = min(l2, size);
 128                 l1_cpy = min(l1, size - l2_cpy);
 129
 130                 if (l1_cpy + l2_cpy == 0)
 131                         break;
 132
 133                 s2_start = l2 - l2_cpy;
 134                 s1_start = l1 - l1_cpy;
 135
 136                 memcpy(dst, s1 + s1_start, l1_cpy);
 137                 memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
 138
 139                 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
 140                                    hsize + l1_cpy + l2_cpy, psinfo);
 141                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 142                         pstore_new_entry = 1;
 143                 l1 -= l1_cpy;
 144                 l2 -= l2_cpy;
 145                 total += l1_cpy + l2_cpy;
 146                 part++;
 147         }
 148         if (in_nmi()) {
 149                 if (is_locked)
 150                         spin_unlock(&psinfo->buf_lock);
 151         } else
 152                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 153 }
 154
 155 static struct kmsg_dumper pstore_dumper = {
 156         .dump = pstore_dump,
 157 };
 158
 159 /*
 160  * platform specific persistent storage driver registers with
 161  * us here. If pstore is already mounted, call the platform
 162  * read function right away to populate the file system. If not
 163  * then the pstore mount code will call us later to fill out
 164  * the file system.
 165  *
 166  * Register with kmsg_dump to save last part of console log on panic.
 167  */
 168 int pstore_register(struct pstore_info *psi)
 169 {
 170         struct module *owner = psi->owner;
 171
 172         spin_lock(&pstore_lock);
 173         if (psinfo) {
 174                 spin_unlock(&pstore_lock);
 175                 return -EBUSY;
 176         }
 177
 178         if (backend && strcmp(backend, psi->name)) {
 179                 spin_unlock(&pstore_lock);
 180                 return -EINVAL;
 181         }
 182
 183         psinfo = psi;
 184         mutex_init(&psinfo->read_mutex);
 185         spin_unlock(&pstore_lock);
 186
 187         if (owner && !try_module_get(owner)) {
 188                 psinfo = NULL;
 189                 return -EINVAL;
 190         }
 191
 192         if (pstore_is_mounted())
 193                 pstore_get_records(0);
 194
 195         kmsg_dump_register(&pstore_dumper);
 196
 197         pstore_timer.expires = jiffies + PSTORE_INTERVAL;
 198         add_timer(&pstore_timer);
 199
 200         return 0;
 201 }
 202 EXPORT_SYMBOL_GPL(pstore_register);
 203
 204 /*
 205  * Read all the records from the persistent store. Create
 206  * files in our filesystem.  Don't warn about -EEXIST errors
 207  * when we are re-scanning the backing store looking to add new
 208  * error records.
 209  */
 210 void pstore_get_records(int quiet)
 211 {
 212         struct pstore_info *psi = psinfo;
 213         char                    *buf = NULL;
 214         ssize_t                 size;
 215         u64                     id;
 216         enum pstore_type_id     type;
 217         struct timespec         time;
 218         int                     failed = 0, rc;
 219
 220         if (!psi)
 221                 return;
 222
 223         mutex_lock(&psi->read_mutex);
 224         if (psi->open && psi->open(psi))
 225                 goto out;
 226
 227         while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
 228                 rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size,
 229                                   time, psi);
 230                 kfree(buf);
 231                 buf = NULL;
 232                 if (rc && (rc != -EEXIST || !quiet))
 233                         failed++;
 234         }
 235         if (psi->close)
 236                 psi->close(psi);
 237 out:
 238         mutex_unlock(&psi->read_mutex);
 239
 240         if (failed)
 241                 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
 242                        failed, psi->name);
 243 }
 244
 245 static void pstore_dowork(struct work_struct *work)
 246 {
 247         pstore_get_records(1);
 248 }
 249
 250 static void pstore_timefunc(unsigned long dummy)
 251 {
 252         if (pstore_new_entry) {
 253                 pstore_new_entry = 0;
 254                 schedule_work(&pstore_work);
 255         }
 256
 257         mod_timer(&pstore_timer, jiffies + PSTORE_INTERVAL);
 258 }
 259
 260 module_param(backend, charp, 0444);
 261 MODULE_PARM_DESC(backend, "Pstore backend to use");