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 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
 100 {
 101         /*
 102          * In case of NMI path, pstore shouldn't be blocked
 103          * regardless of reason.
 104          */
 105         if (in_nmi())
 106                 return true;
 107
 108         switch (reason) {
 109         /* In panic case, other cpus are stopped by smp_send_stop(). */
 110         case KMSG_DUMP_PANIC:
 111         /* Emergency restart shouldn't be blocked by spin lock. */
 112         case KMSG_DUMP_EMERG:
 113                 return true;
 114         default:
 115                 return false;
 116         }
 117 }
 118 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
 119
 120 /*
 121  * callback from kmsg_dump. (s2,l2) has the most recently
 122  * written bytes, older bytes are in (s1,l1). Save as much
 123  * as we can from the end of the buffer.
 124  */
 125 static void pstore_dump(struct kmsg_dumper *dumper,
 126                         enum kmsg_dump_reason reason)
 127 {
 128         unsigned long   total = 0;
 129         const char      *why;
 130         u64             id;
 131         unsigned int    part = 1;
 132         unsigned long   flags = 0;
 133         int             is_locked = 0;
 134         int             ret;
 135
 136         why = get_reason_str(reason);
 137
 138         if (pstore_cannot_block_path(reason)) {
 139                 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
 140                 if (!is_locked) {
 141                         pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
 142                                        , in_nmi() ? "NMI" : why);
 143                 }
 144         } else
 145                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 146         oopscount++;
 147         while (total < kmsg_bytes) {
 148                 char *dst;
 149                 unsigned long size;
 150                 int hsize;
 151                 size_t len;
 152
 153                 dst = psinfo->buf;
 154                 hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
 155                 size = psinfo->bufsize - hsize;
 156                 dst += hsize;
 157
 158                 if (!kmsg_dump_get_buffer(dumper, true, dst, size, &len))
 159                         break;
 160
 161                 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
 162                                     oopscount, hsize, hsize + len, psinfo);
 163                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 164                         pstore_new_entry = 1;
 165
 166                 total += hsize + len;
 167                 part++;
 168         }
 169         if (pstore_cannot_block_path(reason)) {
 170                 if (is_locked)
 171                         spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 172         } else
 173                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 174 }
 175
 176 static struct kmsg_dumper pstore_dumper = {
 177         .dump = pstore_dump,
 178 };
 179
 180 #ifdef CONFIG_PSTORE_CONSOLE
 181 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 182 {
 183         const char *e = s + c;
 184
 185         while (s < e) {
 186                 unsigned long flags;
 187                 u64 id;
 188
 189                 if (c > psinfo->bufsize)
 190                         c = psinfo->bufsize;
 191
 192                 if (oops_in_progress) {
 193                         if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
 194                                 break;
 195                 } else {
 196                         spin_lock_irqsave(&psinfo->buf_lock, flags);
 197                 }
 198                 memcpy(psinfo->buf, s, c);
 199                 psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);
 200                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 201                 s += c;
 202                 c = e - s;
 203         }
 204 }
 205
 206 static struct console pstore_console = {
 207         .name   = "pstore",
 208         .write  = pstore_console_write,
 209         .flags  = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
 210         .index  = -1,
 211 };
 212
 213 static void pstore_register_console(void)
 214 {
 215         register_console(&pstore_console);
 216 }
 217 #else
 218 static void pstore_register_console(void) {}
 219 #endif
 220
 221 static int pstore_write_compat(enum pstore_type_id type,
 222                                enum kmsg_dump_reason reason,
 223                                u64 *id, unsigned int part, int count,
 224                                size_t hsize, size_t size,
 225                                struct pstore_info *psi)
 226 {
 227         return psi->write_buf(type, reason, id, part, psinfo->buf, hsize,
 228                              size, psi);
 229 }
 230
 231 /*
 232  * platform specific persistent storage driver registers with
 233  * us here. If pstore is already mounted, call the platform
 234  * read function right away to populate the file system. If not
 235  * then the pstore mount code will call us later to fill out
 236  * the file system.
 237  *
 238  * Register with kmsg_dump to save last part of console log on panic.
 239  */
 240 int pstore_register(struct pstore_info *psi)
 241 {
 242         struct module *owner = psi->owner;
 243
 244         if (backend && strcmp(backend, psi->name))
 245                 return -EPERM;
 246
 247         spin_lock(&pstore_lock);
 248         if (psinfo) {
 249                 spin_unlock(&pstore_lock);
 250                 return -EBUSY;
 251         }
 252
 253         if (!psi->write)
 254                 psi->write = pstore_write_compat;
 255         psinfo = psi;
 256         mutex_init(&psinfo->read_mutex);
 257         spin_unlock(&pstore_lock);
 258
 259         if (owner && !try_module_get(owner)) {
 260                 psinfo = NULL;
 261                 return -EINVAL;
 262         }
 263
 264         if (pstore_is_mounted())
 265                 pstore_get_records(0);
 266
 267         kmsg_dump_register(&pstore_dumper);
 268         pstore_register_console();
 269         pstore_register_ftrace();
 270
 271         if (pstore_update_ms >= 0) {
 272                 pstore_timer.expires = jiffies +
 273                         msecs_to_jiffies(pstore_update_ms);
 274                 add_timer(&pstore_timer);
 275         }
 276
 277         pr_info("pstore: Registered %s as persistent store backend\n",
 278                 psi->name);
 279
 280         return 0;
 281 }
 282 EXPORT_SYMBOL_GPL(pstore_register);
 283
 284 /*
 285  * Read all the records from the persistent store. Create
 286  * files in our filesystem.  Don't warn about -EEXIST errors
 287  * when we are re-scanning the backing store looking to add new
 288  * error records.
 289  */
 290 void pstore_get_records(int quiet)
 291 {
 292         struct pstore_info *psi = psinfo;
 293         char                    *buf = NULL;
 294         ssize_t                 size;
 295         u64                     id;
 296         int                     count;
 297         enum pstore_type_id     type;
 298         struct timespec         time;
 299         int                     failed = 0, rc;
 300
 301         if (!psi)
 302                 return;
 303
 304         mutex_lock(&psi->read_mutex);
 305         if (psi->open && psi->open(psi))
 306                 goto out;
 307
 308         while ((size = psi->read(&id, &type, &count, &time, &buf, psi)) > 0) {
 309                 rc = pstore_mkfile(type, psi->name, id, count, buf,
 310                                   (size_t)size, time, psi);
 311                 kfree(buf);
 312                 buf = NULL;
 313                 if (rc && (rc != -EEXIST || !quiet))
 314                         failed++;
 315         }
 316         if (psi->close)
 317                 psi->close(psi);
 318 out:
 319         mutex_unlock(&psi->read_mutex);
 320
 321         if (failed)
 322                 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
 323                        failed, psi->name);
 324 }
 325
 326 static void pstore_dowork(struct work_struct *work)
 327 {
 328         pstore_get_records(1);
 329 }
 330
 331 static void pstore_timefunc(unsigned long dummy)
 332 {
 333         if (pstore_new_entry) {
 334                 pstore_new_entry = 0;
 335                 schedule_work(&pstore_work);
 336         }
 337
 338         mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
 339 }
 340
 341 module_param(backend, charp, 0444);
 342 MODULE_PARM_DESC(backend, "Pstore backend to use");