drivers/acpi/apei/erst-dbg.c

   1 /*
   2  * APEI Error Record Serialization Table debug support
   3  *
   4  * ERST is a way provided by APEI to save and retrieve hardware error
   5  * information to and from a persistent store. This file provide the
   6  * debugging/testing support for ERST kernel support and firmware
   7  * implementation.
   8  *
   9  * Copyright 2010 Intel Corp.
  10  *   Author: Huang Ying <ying.huang@intel.com>
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License version
  14  * 2 as published by the Free Software Foundation.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  24  */
  25
  26 #include <linux/kernel.h>
  27 #include <linux/module.h>
  28 #include <linux/uaccess.h>
  29 #include <acpi/apei.h>
  30 #include <linux/miscdevice.h>
  31
  32 #include "apei-internal.h"
  33
  34 #define ERST_DBG_PFX                    "ERST DBG: "
  35
  36 #define ERST_DBG_RECORD_LEN_MAX         4096
  37
  38 static void *erst_dbg_buf;
  39 static unsigned int erst_dbg_buf_len;
  40
  41 /* Prevent erst_dbg_read/write from being invoked concurrently */
  42 static DEFINE_MUTEX(erst_dbg_mutex);
  43
  44 static int erst_dbg_open(struct inode *inode, struct file *file)
  45 {
  46         int rc, *pos;
  47
  48         if (erst_disable)
  49                 return -ENODEV;
  50
  51         pos = (int *)&file->private_data;
  52
  53         rc = erst_get_record_id_begin(pos);
  54         if (rc)
  55                 return rc;
  56
  57         return nonseekable_open(inode, file);
  58 }
  59
  60 static int erst_dbg_release(struct inode *inode, struct file *file)
  61 {
  62         erst_get_record_id_end();
  63
  64         return 0;
  65 }
  66
  67 static long erst_dbg_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
  68 {
  69         int rc;
  70         u64 record_id;
  71         u32 record_count;
  72
  73         switch (cmd) {
  74         case APEI_ERST_CLEAR_RECORD:
  75                 rc = copy_from_user(&record_id, (void __user *)arg,
  76                                     sizeof(record_id));
  77                 if (rc)
  78                         return -EFAULT;
  79                 return erst_clear(record_id);
  80         case APEI_ERST_GET_RECORD_COUNT:
  81                 rc = erst_get_record_count();
  82                 if (rc < 0)
  83                         return rc;
  84                 record_count = rc;
  85                 rc = put_user(record_count, (u32 __user *)arg);
  86                 if (rc)
  87                         return rc;
  88                 return 0;
  89         default:
  90                 return -ENOTTY;
  91         }
  92 }
  93
  94 static ssize_t erst_dbg_read(struct file *filp, char __user *ubuf,
  95                              size_t usize, loff_t *off)
  96 {
  97         int rc, *pos;
  98         ssize_t len = 0;
  99         u64 id;
 100
 101         if (*off)
 102                 return -EINVAL;
 103
 104         if (mutex_lock_interruptible(&erst_dbg_mutex) != 0)
 105                 return -EINTR;
 106
 107         pos = (int *)&filp->private_data;
 108
 109 retry_next:
 110         rc = erst_get_record_id_next(pos, &id);
 111         if (rc)
 112                 goto out;
 113         /* no more record */
 114         if (id == APEI_ERST_INVALID_RECORD_ID)
 115                 goto out;
 116 retry:
 117         rc = len = erst_read(id, erst_dbg_buf, erst_dbg_buf_len);
 118         /* The record may be cleared by others, try read next record */
 119         if (rc == -ENOENT)
 120                 goto retry_next;
 121         if (rc < 0)
 122                 goto out;
 123         if (len > ERST_DBG_RECORD_LEN_MAX) {
 124                 pr_warning(ERST_DBG_PFX
 125                            "Record (ID: 0x%llx) length is too long: %zd\n",
 126                            id, len);
 127                 rc = -EIO;
 128                 goto out;
 129         }
 130         if (len > erst_dbg_buf_len) {
 131                 void *p;
 132                 rc = -ENOMEM;
 133                 p = kmalloc(len, GFP_KERNEL);
 134                 if (!p)
 135                         goto out;
 136                 kfree(erst_dbg_buf);
 137                 erst_dbg_buf = p;
 138                 erst_dbg_buf_len = len;
 139                 goto retry;
 140         }
 141
 142         rc = -EINVAL;
 143         if (len > usize)
 144                 goto out;
 145
 146         rc = -EFAULT;
 147         if (copy_to_user(ubuf, erst_dbg_buf, len))
 148                 goto out;
 149         rc = 0;
 150 out:
 151         mutex_unlock(&erst_dbg_mutex);
 152         return rc ? rc : len;
 153 }
 154
 155 static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf,
 156                               size_t usize, loff_t *off)
 157 {
 158         int rc;
 159         struct cper_record_header *rcd;
 160
 161         if (!capable(CAP_SYS_ADMIN))
 162                 return -EPERM;
 163
 164         if (usize > ERST_DBG_RECORD_LEN_MAX) {
 165                 pr_err(ERST_DBG_PFX "Too long record to be written\n");
 166                 return -EINVAL;
 167         }
 168
 169         if (mutex_lock_interruptible(&erst_dbg_mutex))
 170                 return -EINTR;
 171         if (usize > erst_dbg_buf_len) {
 172                 void *p;
 173                 rc = -ENOMEM;
 174                 p = kmalloc(usize, GFP_KERNEL);
 175                 if (!p)
 176                         goto out;
 177                 kfree(erst_dbg_buf);
 178                 erst_dbg_buf = p;
 179                 erst_dbg_buf_len = usize;
 180         }
 181         rc = copy_from_user(erst_dbg_buf, ubuf, usize);
 182         if (rc) {
 183                 rc = -EFAULT;
 184                 goto out;
 185         }
 186         rcd = erst_dbg_buf;
 187         rc = -EINVAL;
 188         if (rcd->record_length != usize)
 189                 goto out;
 190
 191         rc = erst_write(erst_dbg_buf);
 192
 193 out:
 194         mutex_unlock(&erst_dbg_mutex);
 195         return rc < 0 ? rc : usize;
 196 }
 197
 198 static const struct file_operations erst_dbg_ops = {
 199         .owner          = THIS_MODULE,
 200         .open           = erst_dbg_open,
 201         .release        = erst_dbg_release,
 202         .read           = erst_dbg_read,
 203         .write          = erst_dbg_write,
 204         .unlocked_ioctl = erst_dbg_ioctl,
 205         .llseek         = no_llseek,
 206 };
 207
 208 static struct miscdevice erst_dbg_dev = {
 209         .minor  = MISC_DYNAMIC_MINOR,
 210         .name   = "erst_dbg",
 211         .fops   = &erst_dbg_ops,
 212 };
 213
 214 static __init int erst_dbg_init(void)
 215 {
 216         return misc_register(&erst_dbg_dev);
 217 }
 218
 219 static __exit void erst_dbg_exit(void)
 220 {
 221         misc_deregister(&erst_dbg_dev);
 222         kfree(erst_dbg_buf);
 223 }
 224
 225 module_init(erst_dbg_init);
 226 module_exit(erst_dbg_exit);
 227
 228 MODULE_AUTHOR("Huang Ying");
 229 MODULE_DESCRIPTION("APEI Error Record Serialization Table debug support");
 230 MODULE_LICENSE("GPL");