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