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/slab.h>
  29 #include <linux/uaccess.h>
  30
  31 #include "internal.h"
  32
  33 /*
  34  * pstore_lock just protects "psinfo" during
  35  * calls to pstore_register()
  36  */
  37 static DEFINE_SPINLOCK(pstore_lock);
  38 static struct pstore_info *psinfo;
  39
  40 static char *backend;
  41
  42 /* How much of the console log to snapshot */
  43 static unsigned long kmsg_bytes = 10240;
  44
  45 void pstore_set_kmsg_bytes(int bytes)
  46 {
  47         kmsg_bytes = bytes;
  48 }
  49
  50 /* Tag each group of saved records with a sequence number */
  51 static int      oopscount;
  52
  53 static char *reason_str[] = {
  54         "Oops", "Panic", "Kexec", "Restart", "Halt", "Poweroff", "Emergency"
  55 };
  56
  57 /*
  58  * callback from kmsg_dump. (s2,l2) has the most recently
  59  * written bytes, older bytes are in (s1,l1). Save as much
  60  * as we can from the end of the buffer.
  61  */
  62 static void pstore_dump(struct kmsg_dumper *dumper,
  63             enum kmsg_dump_reason reason,
  64             const char *s1, unsigned long l1,
  65             const char *s2, unsigned long l2)
  66 {
  67         unsigned long   s1_start, s2_start;
  68         unsigned long   l1_cpy, l2_cpy;
  69         unsigned long   size, total = 0;
  70         char            *dst, *why;
  71         u64             id;
  72         int             hsize;
  73         unsigned int    part = 1;
  74
  75         if (reason < ARRAY_SIZE(reason_str))
  76                 why = reason_str[reason];
  77         else
  78                 why = "Unknown";
  79
  80         mutex_lock(&psinfo->buf_mutex);
  81         oopscount++;
  82         while (total < kmsg_bytes) {
  83                 dst = psinfo->buf;
  84                 hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
  85                 size = psinfo->bufsize - hsize;
  86                 dst += hsize;
  87
  88                 l2_cpy = min(l2, size);
  89                 l1_cpy = min(l1, size - l2_cpy);
  90
  91                 if (l1_cpy + l2_cpy == 0)
  92                         break;
  93
  94                 s2_start = l2 - l2_cpy;
  95                 s1_start = l1 - l1_cpy;
  96
  97                 memcpy(dst, s1 + s1_start, l1_cpy);
  98                 memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
  99
 100                 id = psinfo->write(PSTORE_TYPE_DMESG, part,
 101                                    hsize + l1_cpy + l2_cpy, psinfo);
 102                 if (reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 103                         pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id,
 104                                       psinfo->buf, hsize + l1_cpy + l2_cpy,
 105                                       CURRENT_TIME, psinfo);
 106                 l1 -= l1_cpy;
 107                 l2 -= l2_cpy;
 108                 total += l1_cpy + l2_cpy;
 109                 part++;
 110         }
 111         mutex_unlock(&psinfo->buf_mutex);
 112 }
 113
 114 static struct kmsg_dumper pstore_dumper = {
 115         .dump = pstore_dump,
 116 };
 117
 118 /*
 119  * platform specific persistent storage driver registers with
 120  * us here. If pstore is already mounted, call the platform
 121  * read function right away to populate the file system. If not
 122  * then the pstore mount code will call us later to fill out
 123  * the file system.
 124  *
 125  * Register with kmsg_dump to save last part of console log on panic.
 126  */
 127 int pstore_register(struct pstore_info *psi)
 128 {
 129         struct module *owner = psi->owner;
 130
 131         spin_lock(&pstore_lock);
 132         if (psinfo) {
 133                 spin_unlock(&pstore_lock);
 134                 return -EBUSY;
 135         }
 136
 137         if (backend && strcmp(backend, psi->name)) {
 138                 spin_unlock(&pstore_lock);
 139                 return -EINVAL;
 140         }
 141
 142         psinfo = psi;
 143         spin_unlock(&pstore_lock);
 144
 145         if (owner && !try_module_get(owner)) {
 146                 psinfo = NULL;
 147                 return -EINVAL;
 148         }
 149
 150         if (pstore_is_mounted())
 151                 pstore_get_records();
 152
 153         kmsg_dump_register(&pstore_dumper);
 154
 155         return 0;
 156 }
 157 EXPORT_SYMBOL_GPL(pstore_register);
 158
 159 /*
 160  * Read all the records from the persistent store. Create and
 161  * file files in our filesystem.
 162  */
 163 void pstore_get_records(void)
 164 {
 165         struct pstore_info *psi = psinfo;
 166         ssize_t                 size;
 167         u64                     id;
 168         enum pstore_type_id     type;
 169         struct timespec         time;
 170         int                     failed = 0, rc;
 171
 172         if (!psi)
 173                 return;
 174
 175         mutex_lock(&psinfo->buf_mutex);
 176         rc = psi->open(psi);
 177         if (rc)
 178                 goto out;
 179
 180         while ((size = psi->read(&id, &type, &time, psi)) > 0) {
 181                 if (pstore_mkfile(type, psi->name, id, psi->buf, (size_t)size,
 182                                   time, psi))
 183                         failed++;
 184         }
 185         psi->close(psi);
 186 out:
 187         mutex_unlock(&psinfo->buf_mutex);
 188
 189         if (failed)
 190                 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
 191                        failed, psi->name);
 192 }
 193
 194 /*
 195  * Call platform driver to write a record to the
 196  * persistent store.
 197  */
 198 int pstore_write(enum pstore_type_id type, char *buf, size_t size)
 199 {
 200         u64     id;
 201
 202         if (!psinfo)
 203                 return -ENODEV;
 204
 205         if (size > psinfo->bufsize)
 206                 return -EFBIG;
 207
 208         mutex_lock(&psinfo->buf_mutex);
 209         memcpy(psinfo->buf, buf, size);
 210         id = psinfo->write(type, 0, size, psinfo);
 211         if (pstore_is_mounted())
 212                 pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, psinfo->buf,
 213                               size, CURRENT_TIME, psinfo);
 214         mutex_unlock(&psinfo->buf_mutex);
 215
 216         return 0;
 217 }
 218 EXPORT_SYMBOL_GPL(pstore_write);
 219
 220 module_param(backend, charp, 0444);
 221 MODULE_PARM_DESC(backend, "Pstore backend to use");