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