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 char *reason_str[] = {
  72         "Oops", "Panic", "Kexec", "Restart", "Halt", "Poweroff", "Emergency"
  73 };
  74
  75 /*
  76  * callback from kmsg_dump. (s2,l2) has the most recently
  77  * written bytes, older bytes are in (s1,l1). Save as much
  78  * as we can from the end of the buffer.
  79  */
  80 static void pstore_dump(struct kmsg_dumper *dumper,
  81             enum kmsg_dump_reason reason,
  82             const char *s1, unsigned long l1,
  83             const char *s2, unsigned long l2)
  84 {
  85         unsigned long   s1_start, s2_start;
  86         unsigned long   l1_cpy, l2_cpy;
  87         unsigned long   size, total = 0;
  88         char            *dst, *why;
  89         u64             id;
  90         int             hsize, ret;
  91         unsigned int    part = 1;
  92         unsigned long   flags = 0;
  93         int             is_locked = 0;
  94
  95         if (reason < ARRAY_SIZE(reason_str))
  96                 why = reason_str[reason];
  97         else
  98                 why = "Unknown";
  99
 100         if (in_nmi()) {
 101                 is_locked = spin_trylock(&psinfo->buf_lock);
 102                 if (!is_locked)
 103                         pr_err("pstore dump routine blocked in NMI, may corrupt error record\n");
 104         } else
 105                 spin_lock_irqsave(&psinfo->buf_lock, flags);
 106         oopscount++;
 107         while (total < kmsg_bytes) {
 108                 dst = psinfo->buf;
 109                 hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
 110                 size = psinfo->bufsize - hsize;
 111                 dst += hsize;
 112
 113                 l2_cpy = min(l2, size);
 114                 l1_cpy = min(l1, size - l2_cpy);
 115
 116                 if (l1_cpy + l2_cpy == 0)
 117                         break;
 118
 119                 s2_start = l2 - l2_cpy;
 120                 s1_start = l1 - l1_cpy;
 121
 122                 memcpy(dst, s1 + s1_start, l1_cpy);
 123                 memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
 124
 125                 ret = psinfo->write(PSTORE_TYPE_DMESG, &id, part,
 126                                    hsize + l1_cpy + l2_cpy, psinfo);
 127                 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 128                         pstore_new_entry = 1;
 129                 l1 -= l1_cpy;
 130                 l2 -= l2_cpy;
 131                 total += l1_cpy + l2_cpy;
 132                 part++;
 133         }
 134         if (in_nmi()) {
 135                 if (is_locked)
 136                         spin_unlock(&psinfo->buf_lock);
 137         } else
 138                 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 139 }
 140
 141 static struct kmsg_dumper pstore_dumper = {
 142         .dump = pstore_dump,
 143 };
 144
 145 /*
 146  * platform specific persistent storage driver registers with
 147  * us here. If pstore is already mounted, call the platform
 148  * read function right away to populate the file system. If not
 149  * then the pstore mount code will call us later to fill out
 150  * the file system.
 151  *
 152  * Register with kmsg_dump to save last part of console log on panic.
 153  */
 154 int pstore_register(struct pstore_info *psi)
 155 {
 156         struct module *owner = psi->owner;
 157
 158         spin_lock(&pstore_lock);
 159         if (psinfo) {
 160                 spin_unlock(&pstore_lock);
 161                 return -EBUSY;
 162         }
 163
 164         if (backend && strcmp(backend, psi->name)) {
 165                 spin_unlock(&pstore_lock);
 166                 return -EINVAL;
 167         }
 168
 169         psinfo = psi;
 170         mutex_init(&psinfo->read_mutex);
 171         spin_unlock(&pstore_lock);
 172
 173         if (owner && !try_module_get(owner)) {
 174                 psinfo = NULL;
 175                 return -EINVAL;
 176         }
 177
 178         if (pstore_is_mounted())
 179                 pstore_get_records(0);
 180
 181         kmsg_dump_register(&pstore_dumper);
 182
 183         pstore_timer.expires = jiffies + PSTORE_INTERVAL;
 184         add_timer(&pstore_timer);
 185
 186         return 0;
 187 }
 188 EXPORT_SYMBOL_GPL(pstore_register);
 189
 190 /*
 191  * Read all the records from the persistent store. Create
 192  * files in our filesystem.  Don't warn about -EEXIST errors
 193  * when we are re-scanning the backing store looking to add new
 194  * error records.
 195  */
 196 void pstore_get_records(int quiet)
 197 {
 198         struct pstore_info *psi = psinfo;
 199         char                    *buf = NULL;
 200         ssize_t                 size;
 201         u64                     id;
 202         enum pstore_type_id     type;
 203         struct timespec         time;
 204         int                     failed = 0, rc;
 205
 206         if (!psi)
 207                 return;
 208
 209         mutex_lock(&psi->read_mutex);
 210         rc = psi->open(psi);
 211         if (rc)
 212                 goto out;
 213
 214         while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
 215                 rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size,
 216                                   time, psi);
 217                 kfree(buf);
 218                 buf = NULL;
 219                 if (rc && (rc != -EEXIST || !quiet))
 220                         failed++;
 221         }
 222         psi->close(psi);
 223 out:
 224         mutex_unlock(&psi->read_mutex);
 225
 226         if (failed)
 227                 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
 228                        failed, psi->name);
 229 }
 230
 231 static void pstore_dowork(struct work_struct *work)
 232 {
 233         pstore_get_records(1);
 234 }
 235
 236 static void pstore_timefunc(unsigned long dummy)
 237 {
 238         if (pstore_new_entry) {
 239                 pstore_new_entry = 0;
 240                 schedule_work(&pstore_work);
 241         }
 242
 243         mod_timer(&pstore_timer, jiffies + PSTORE_INTERVAL);
 244 }
 245
 246 /*
 247  * Call platform driver to write a record to the
 248  * persistent store.
 249  */
 250 int pstore_write(enum pstore_type_id type, char *buf, size_t size)
 251 {
 252         u64             id;
 253         int             ret;
 254         unsigned long   flags;
 255
 256         if (!psinfo)
 257                 return -ENODEV;
 258
 259         if (size > psinfo->bufsize)
 260                 return -EFBIG;
 261
 262         spin_lock_irqsave(&psinfo->buf_lock, flags);
 263         memcpy(psinfo->buf, buf, size);
 264         ret = psinfo->write(type, &id, 0, size, psinfo);
 265         if (ret == 0 && pstore_is_mounted())
 266                 pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, psinfo->buf,
 267                               size, CURRENT_TIME, psinfo);
 268         spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 269
 270         return 0;
 271 }
 272 EXPORT_SYMBOL_GPL(pstore_write);
 273
 274 module_param(backend, charp, 0444);
 275 MODULE_PARM_DESC(backend, "Pstore backend to use");