fs/pstore/platform.c

   1 /*
   2  * Persistent Storage - platform driver interface parts.
   3  *
   4  * Copyright (C) 2007-2008 Google, Inc.
   5  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2 as
   9  *  published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include <linux/atomic.h>
  22 #include <linux/types.h>
  23 #include <linux/errno.h>
  24 #include <linux/init.h>
  25 #include <linux/kmsg_dump.h>
  26 #include <linux/console.h>
  27 #include <linux/module.h>
  28 #include <linux/pstore.h>
  29 #include <linux/string.h>
  30 #include <linux/timer.h>
  31 #include <linux/slab.h>
  32 #include <linux/uaccess.h>
  33 #include <linux/hardirq.h>
  34 #include <linux/jiffies.h>
  35 #include <linux/workqueue.h>
  36
  37 #include "internal.h"
  38
  39 /*
  40  * We defer making "oops" entries appear in pstore - see
  41  * whether the system is actually still running well enough
  42  * to let someone see the entry
  43  */
  44 static int pstore_update_ms = -1;
  45 module_param_named(update_ms, pstore_update_ms, int, 0600);
  46 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
  47                  "(default is -1, which means runtime updates are disabled; "
  48                  "enabling this option is not safe, it may lead to further "
  49                  "corruption on Oopses)");
  50
  51 static int pstore_new_entry;
  52
  53 static void pstore_timefunc(unsigned long);
  54 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
  55
  56 static void pstore_dowork(struct work_struct *);
  57 static DECLARE_WORK(pstore_work, pstore_dowork);
  58
  59 /*
  60  * pstore_lock just protects "psinfo" during
  61  * calls to pstore_register()
  62  */
  63 static DEFINE_SPINLOCK(pstore_lock);
  64 struct pstore_info *psinfo;
  65
  66 static char *backend;
  67
  68 /* How much of the console log to snapshot */
  69 static unsigned long kmsg_bytes = 10240;
  70
  71 void pstore_set_kmsg_bytes(int bytes)
  72 {
  73         kmsg_bytes = bytes;
  74 }
  75
  76 /* Tag each group of saved records with a sequence number */
  77 static int      oopscount;
  78
  79 static const char *get_reason_str(enum kmsg_dump_reason reason)
  80 {
  81         switch (reason) {
  82         case KMSG_DUMP_PANIC:
  83                 return "Panic";
  84         case KMSG_DUMP_OOPS:
  85                 return "Oops";
  86         case KMSG_DUMP_EMERG:
  87                 return "Emergency";
  88         case KMSG_DUMP_RESTART:
  89                 return "Restart";
  90         case KMSG_DUMP_HALT:
  91                 return "Halt";
  92         case KMSG_DUMP_POWEROFF:
  93                 return "Poweroff";
  94         default:
  95                 return "Unknown";
  96         }
  97 }
  98
  99 /*
 100  * callback from kmsg_dump. (s2,l2) has the most recently
 101  * written bytes, older bytes are in (s1,l1). Save as much
 102  * as we can from the end of the buffer.
 103  */
 104 static void pstore_dump(struct kmsg_dumper *dumper,
 105                         enum kmsg_dump_reason reason)
 106 {
 107         unsigned long   total = 0;
 108         const char      *why;
 109         u64             id;
 110         unsigned int    part = 1;
 111         unsigned long   flags = 0;
 112         int             is_locked = 0;
 113         int             ret;
 114
 115         why = get_reason_str(reason);
 116
 117         if (in_nmi()) {
 118                 is_locked = spin_trylock(&psinfo->buf_lock);
 119                 if (!is_locked)
 120                         pr_err("pstore dump routine blocked in NMI, may corrupt error record\n");
 121         } else
 122                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 123         oopscount++;
 124         while (total < kmsg_bytes) {
 125                 char *dst;
 126                 unsigned long size;
 127                 int hsize;
 128                 size_t len;
 129
 130                 dst = psinfo->buf;
 131                 hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
 132                 size = psinfo->bufsize - hsize;
 133                 dst += hsize;
 134
 135                 if (!kmsg_dump_get_buffer(dumper, true, dst, size, &len))
 136                         break;
 137
 138                 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
 139                                     hsize + len, psinfo);
 140                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 141                         pstore_new_entry = 1;
 142
 143                 total += hsize + len;
 144                 part++;
 145         }
 146         if (in_nmi()) {
 147                 if (is_locked)
 148                         spin_unlock(&psinfo->buf_lock);
 149         } else
 150                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 151 }
 152
 153 static struct kmsg_dumper pstore_dumper = {
 154         .dump = pstore_dump,
 155 };
 156
 157 #ifdef CONFIG_PSTORE_CONSOLE
 158 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 159 {
 160         const char *e = s + c;
 161
 162         while (s < e) {
 163                 unsigned long flags;
 164
 165                 if (c > psinfo->bufsize)
 166                         c = psinfo->bufsize;
 167                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 168                 memcpy(psinfo->buf, s, c);
 169                 psinfo->write(PSTORE_TYPE_CONSOLE, 0, NULL, 0, c, psinfo);
 170                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 171                 s += c;
 172                 c = e - s;
 173         }
 174 }
 175
 176 static struct console pstore_console = {
 177         .name   = "pstore",
 178         .write  = pstore_console_write,
 179         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 180         .index  = -1,
 181 };
 182
 183 static void pstore_register_console(void)
 184 {
 185         register_console(&pstore_console);
 186 }
 187 #else
 188 static void pstore_register_console(void) {}
 189 #endif
 190
 191 static int pstore_write_compat(enum pstore_type_id type,
 192                                enum kmsg_dump_reason reason,
 193                                u64 *id, unsigned int part,
 194                                size_t size, struct pstore_info *psi)
 195 {
 196         return psi->write_buf(type, reason, id, part, psinfo->buf, size, psi);
 197 }
 198
 199 /*
 200  * platform specific persistent storage driver registers with
 201  * us here. If pstore is already mounted, call the platform
 202  * read function right away to populate the file system. If not
 203  * then the pstore mount code will call us later to fill out
 204  * the file system.
 205  *
 206  * Register with kmsg_dump to save last part of console log on panic.
 207  */
 208 int pstore_register(struct pstore_info *psi)
 209 {
 210         struct module *owner = psi->owner;
 211
 212         spin_lock(&pstore_lock);
 213         if (psinfo) {
 214                 spin_unlock(&pstore_lock);
 215                 return -EBUSY;
 216         }
 217
 218         if (backend && strcmp(backend, psi->name)) {
 219                 spin_unlock(&pstore_lock);
 220                 return -EINVAL;
 221         }
 222
 223         if (!psi->write)
 224                 psi->write = pstore_write_compat;
 225         psinfo = psi;
 226         mutex_init(&psinfo->read_mutex);
 227         spin_unlock(&pstore_lock);
 228
 229         if (owner && !try_module_get(owner)) {
 230                 psinfo = NULL;
 231                 return -EINVAL;
 232         }
 233
 234         if (pstore_is_mounted())
 235                 pstore_get_records(0);
 236
 237         kmsg_dump_register(&pstore_dumper);
 238         pstore_register_console();
 239
 240         if (pstore_update_ms >= 0) {
 241                 pstore_timer.expires = jiffies +
 242                         msecs_to_jiffies(pstore_update_ms);
 243                 add_timer(&pstore_timer);
 244         }
 245
 246         return 0;
 247 }
 248 EXPORT_SYMBOL_GPL(pstore_register);
 249
 250 /*
 251  * Read all the records from the persistent store. Create
 252  * files in our filesystem.  Don't warn about -EEXIST errors
 253  * when we are re-scanning the backing store looking to add new
 254  * error records.
 255  */
 256 void pstore_get_records(int quiet)
 257 {
 258         struct pstore_info *psi = psinfo;
 259         char                    *buf = NULL;
 260         ssize_t                 size;
 261         u64                     id;
 262         enum pstore_type_id     type;
 263         struct timespec         time;
 264         int                     failed = 0, rc;
 265
 266         if (!psi)
 267                 return;
 268
 269         mutex_lock(&psi->read_mutex);
 270         if (psi->open && psi->open(psi))
 271                 goto out;
 272
 273         while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
 274                 rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size,
 275                                   time, psi);
 276                 kfree(buf);
 277                 buf = NULL;
 278                 if (rc && (rc != -EEXIST || !quiet))
 279                         failed++;
 280         }
 281         if (psi->close)
 282                 psi->close(psi);
 283 out:
 284         mutex_unlock(&psi->read_mutex);
 285
 286         if (failed)
 287                 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
 288                        failed, psi->name);
 289 }
 290
 291 static void pstore_dowork(struct work_struct *work)
 292 {
 293         pstore_get_records(1);
 294 }
 295
 296 static void pstore_timefunc(unsigned long dummy)
 297 {
 298         if (pstore_new_entry) {
 299                 pstore_new_entry = 0;
 300                 schedule_work(&pstore_work);
 301         }
 302
 303         mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
 304 }
 305
 306 module_param(backend, charp, 0444);
 307 MODULE_PARM_DESC(backend, "Pstore backend to use");