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                                     oopscount, 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                 u64 id;
 165
 166                 if (c > psinfo->bufsize)
 167                         c = psinfo->bufsize;
 168
 169                 if (oops_in_progress) {
 170                         if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
 171                                 break;
 172                 } else {
 173                         spin_lock_irqsave(&psinfo->buf_lock, flags);
 174                 }
 175                 memcpy(psinfo->buf, s, c);
 176                 psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, c, psinfo);
 177                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 178                 s += c;
 179                 c = e - s;
 180         }
 181 }
 182
 183 static struct console pstore_console = {
 184         .name   = "pstore",
 185         .write  = pstore_console_write,
 186         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 187         .index  = -1,
 188 };
 189
 190 static void pstore_register_console(void)
 191 {
 192         register_console(&pstore_console);
 193 }
 194 #else
 195 static void pstore_register_console(void) {}
 196 #endif
 197
 198 static int pstore_write_compat(enum pstore_type_id type,
 199                                enum kmsg_dump_reason reason,
 200                                u64 *id, unsigned int part, int count,
 201                                size_t size, struct pstore_info *psi)
 202 {
 203         return psi->write_buf(type, reason, id, part, psinfo->buf, size, psi);
 204 }
 205
 206 /*
 207  * platform specific persistent storage driver registers with
 208  * us here. If pstore is already mounted, call the platform
 209  * read function right away to populate the file system. If not
 210  * then the pstore mount code will call us later to fill out
 211  * the file system.
 212  *
 213  * Register with kmsg_dump to save last part of console log on panic.
 214  */
 215 int pstore_register(struct pstore_info *psi)
 216 {
 217         struct module *owner = psi->owner;
 218
 219         spin_lock(&pstore_lock);
 220         if (psinfo) {
 221                 spin_unlock(&pstore_lock);
 222                 return -EBUSY;
 223         }
 224
 225         if (backend && strcmp(backend, psi->name)) {
 226                 spin_unlock(&pstore_lock);
 227                 return -EINVAL;
 228         }
 229
 230         if (!psi->write)
 231                 psi->write = pstore_write_compat;
 232         psinfo = psi;
 233         mutex_init(&psinfo->read_mutex);
 234         spin_unlock(&pstore_lock);
 235
 236         if (owner && !try_module_get(owner)) {
 237                 psinfo = NULL;
 238                 return -EINVAL;
 239         }
 240
 241         if (pstore_is_mounted())
 242                 pstore_get_records(0);
 243
 244         kmsg_dump_register(&pstore_dumper);
 245         pstore_register_console();
 246         pstore_register_ftrace();
 247
 248         if (pstore_update_ms >= 0) {
 249                 pstore_timer.expires = jiffies +
 250                         msecs_to_jiffies(pstore_update_ms);
 251                 add_timer(&pstore_timer);
 252         }
 253
 254         return 0;
 255 }
 256 EXPORT_SYMBOL_GPL(pstore_register);
 257
 258 /*
 259  * Read all the records from the persistent store. Create
 260  * files in our filesystem.  Don't warn about -EEXIST errors
 261  * when we are re-scanning the backing store looking to add new
 262  * error records.
 263  */
 264 void pstore_get_records(int quiet)
 265 {
 266         struct pstore_info *psi = psinfo;
 267         char                    *buf = NULL;
 268         ssize_t                 size;
 269         u64                     id;
 270         int                     count;
 271         enum pstore_type_id     type;
 272         struct timespec         time;
 273         int                     failed = 0, rc;
 274
 275         if (!psi)
 276                 return;
 277
 278         mutex_lock(&psi->read_mutex);
 279         if (psi->open && psi->open(psi))
 280                 goto out;
 281
 282         while ((size = psi->read(&id, &type, &count, &time, &buf, psi)) > 0) {
 283                 rc = pstore_mkfile(type, psi->name, id, count, buf,
 284                                   (size_t)size, time, psi);
 285                 kfree(buf);
 286                 buf = NULL;
 287                 if (rc && (rc != -EEXIST || !quiet))
 288                         failed++;
 289         }
 290         if (psi->close)
 291                 psi->close(psi);
 292 out:
 293         mutex_unlock(&psi->read_mutex);
 294
 295         if (failed)
 296                 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
 297                        failed, psi->name);
 298 }
 299
 300 static void pstore_dowork(struct work_struct *work)
 301 {
 302         pstore_get_records(1);
 303 }
 304
 305 static void pstore_timefunc(unsigned long dummy)
 306 {
 307         if (pstore_new_entry) {
 308                 pstore_new_entry = 0;
 309                 schedule_work(&pstore_work);
 310         }
 311
 312         mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
 313 }
 314
 315 module_param(backend, charp, 0444);
 316 MODULE_PARM_DESC(backend, "Pstore backend to use");