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
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/uaccess.h>
  25 #include <acpi/apei.h>
  26 #include <linux/miscdevice.h>
  27
  28 #include "apei-internal.h"
  29
  30 #define ERST_DBG_PFX                    "ERST DBG: "
  31
  32 #define ERST_DBG_RECORD_LEN_MAX         0x4000
  33
  34 static void *erst_dbg_buf;
  35 static unsigned int erst_dbg_buf_len;
  36
  37 /* Prevent erst_dbg_read/write from being invoked concurrently */
  38 static DEFINE_MUTEX(erst_dbg_mutex);
  39
  40 static int erst_dbg_open(struct inode *inode, struct file *file)
  41 {
  42         int rc, *pos;
  43
  44         if (erst_disable)
  45                 return -ENODEV;
  46
  47         pos = (int *)&file->private_data;
  48
  49         rc = erst_get_record_id_begin(pos);
  50         if (rc)
  51                 return rc;
  52
  53         return nonseekable_open(inode, file);
  54 }
  55
  56 static int erst_dbg_release(struct inode *inode, struct file *file)
  57 {
  58         erst_get_record_id_end();
  59
  60         return 0;
  61 }
  62
  63 static long erst_dbg_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
  64 {
  65         int rc;
  66         u64 record_id;
  67         u32 record_count;
  68
  69         switch (cmd) {
  70         case APEI_ERST_CLEAR_RECORD:
  71                 rc = copy_from_user(&record_id, (void __user *)arg,
  72                                     sizeof(record_id));
  73                 if (rc)
  74                         return -EFAULT;
  75                 return erst_clear(record_id);
  76         case APEI_ERST_GET_RECORD_COUNT:
  77                 rc = erst_get_record_count();
  78                 if (rc < 0)
  79                         return rc;
  80                 record_count = rc;
  81                 rc = put_user(record_count, (u32 __user *)arg);
  82                 if (rc)
  83                         return rc;
  84                 return 0;
  85         default:
  86                 return -ENOTTY;
  87         }
  88 }
  89
  90 static ssize_t erst_dbg_read(struct file *filp, char __user *ubuf,
  91                              size_t usize, loff_t *off)
  92 {
  93         int rc, *pos;
  94         ssize_t len = 0;
  95         u64 id;
  96
  97         if (*off)
  98                 return -EINVAL;
  99
 100         if (mutex_lock_interruptible(&erst_dbg_mutex) != 0)
 101                 return -EINTR;
 102
 103         pos = (int *)&filp->private_data;
 104
 105 retry_next:
 106         rc = erst_get_record_id_next(pos, &id);
 107         if (rc)
 108                 goto out;
 109         /* no more record */
 110         if (id == APEI_ERST_INVALID_RECORD_ID) {
 111                 /*
 112                  * If the persistent store is empty initially, the function
 113                  * 'erst_read' below will return "-ENOENT" value. This causes
 114                  * 'retry_next' label is entered again. The returned value
 115                  * should be zero indicating the read operation is EOF.
 116                  */
 117                 len = 0;
 118
 119                 goto out;
 120         }
 121 retry:
 122         rc = len = erst_read(id, erst_dbg_buf, erst_dbg_buf_len);
 123         /* The record may be cleared by others, try read next record */
 124         if (rc == -ENOENT)
 125                 goto retry_next;
 126         if (rc < 0)
 127                 goto out;
 128         if (len > ERST_DBG_RECORD_LEN_MAX) {
 129                 pr_warning(ERST_DBG_PFX
 130                            "Record (ID: 0x%llx) length is too long: %zd\n",
 131                            id, len);
 132                 rc = -EIO;
 133                 goto out;
 134         }
 135         if (len > erst_dbg_buf_len) {
 136                 void *p;
 137                 rc = -ENOMEM;
 138                 p = kmalloc(len, GFP_KERNEL);
 139                 if (!p)
 140                         goto out;
 141                 kfree(erst_dbg_buf);
 142                 erst_dbg_buf = p;
 143                 erst_dbg_buf_len = len;
 144                 goto retry;
 145         }
 146
 147         rc = -EINVAL;
 148         if (len > usize)
 149                 goto out;
 150
 151         rc = -EFAULT;
 152         if (copy_to_user(ubuf, erst_dbg_buf, len))
 153                 goto out;
 154         rc = 0;
 155 out:
 156         mutex_unlock(&erst_dbg_mutex);
 157         return rc ? rc : len;
 158 }
 159
 160 static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf,
 161                               size_t usize, loff_t *off)
 162 {
 163         int rc;
 164         struct cper_record_header *rcd;
 165
 166         if (!capable(CAP_SYS_ADMIN))
 167                 return -EPERM;
 168
 169         if (usize > ERST_DBG_RECORD_LEN_MAX) {
 170                 pr_err(ERST_DBG_PFX "Too long record to be written\n");
 171                 return -EINVAL;
 172         }
 173
 174         if (mutex_lock_interruptible(&erst_dbg_mutex))
 175                 return -EINTR;
 176         if (usize > erst_dbg_buf_len) {
 177                 void *p;
 178                 rc = -ENOMEM;
 179                 p = kmalloc(usize, GFP_KERNEL);
 180                 if (!p)
 181                         goto out;
 182                 kfree(erst_dbg_buf);
 183                 erst_dbg_buf = p;
 184                 erst_dbg_buf_len = usize;
 185         }
 186         rc = copy_from_user(erst_dbg_buf, ubuf, usize);
 187         if (rc) {
 188                 rc = -EFAULT;
 189                 goto out;
 190         }
 191         rcd = erst_dbg_buf;
 192         rc = -EINVAL;
 193         if (rcd->record_length != usize)
 194                 goto out;
 195
 196         rc = erst_write(erst_dbg_buf);
 197
 198 out:
 199         mutex_unlock(&erst_dbg_mutex);
 200         return rc < 0 ? rc : usize;
 201 }
 202
 203 static const struct file_operations erst_dbg_ops = {
 204         .owner          = THIS_MODULE,
 205         .open           = erst_dbg_open,
 206         .release        = erst_dbg_release,
 207         .read           = erst_dbg_read,
 208         .write          = erst_dbg_write,
 209         .unlocked_ioctl = erst_dbg_ioctl,
 210         .llseek         = no_llseek,
 211 };
 212
 213 static struct miscdevice erst_dbg_dev = {
 214         .minor  = MISC_DYNAMIC_MINOR,
 215         .name   = "erst_dbg",
 216         .fops   = &erst_dbg_ops,
 217 };
 218
 219 static __init int erst_dbg_init(void)
 220 {
 221         if (erst_disable) {
 222                 pr_info(ERST_DBG_PFX "ERST support is disabled.\n");
 223                 return -ENODEV;
 224         }
 225         return misc_register(&erst_dbg_dev);
 226 }
 227
 228 static __exit void erst_dbg_exit(void)
 229 {
 230         misc_deregister(&erst_dbg_dev);
 231         kfree(erst_dbg_buf);
 232 }
 233
 234 module_init(erst_dbg_init);
 235 module_exit(erst_dbg_exit);
 236
 237 MODULE_AUTHOR("Huang Ying");
 238 MODULE_DESCRIPTION("APEI Error Record Serialization Table debug support");
 239 MODULE_LICENSE("GPL");