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