drivers/acpi/apei/erst-dbg.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * APEI Error Record Serialization Table debug support
   4  *
   5  * ERST is a way provided by APEI to save and retrieve hardware error
   6  * information to and from a persistent store. This file provide the
   7  * debugging/testing support for ERST kernel support and firmware
   8  * implementation.
   9  *
  10  * Copyright 2010 Intel Corp.
  11  *   Author: Huang Ying <ying.huang@intel.com>
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/uaccess.h>
  17 #include <acpi/apei.h>
  18 #include <linux/miscdevice.h>
  19
  20 #include "apei-internal.h"
  21
  22 #define ERST_DBG_PFX                    "ERST DBG: "
  23
  24 #define ERST_DBG_RECORD_LEN_MAX         0x4000
  25
  26 static void *erst_dbg_buf;
  27 static unsigned int erst_dbg_buf_len;
  28
  29 /* Prevent erst_dbg_read/write from being invoked concurrently */
  30 static DEFINE_MUTEX(erst_dbg_mutex);
  31
  32 static int erst_dbg_open(struct inode *inode, struct file *file)
  33 {
  34         int rc, *pos;
  35
  36         if (erst_disable)
  37                 return -ENODEV;
  38
  39         pos = (int *)&file->private_data;
  40
  41         rc = erst_get_record_id_begin(pos);
  42         if (rc)
  43                 return rc;
  44
  45         return nonseekable_open(inode, file);
  46 }
  47
  48 static int erst_dbg_release(struct inode *inode, struct file *file)
  49 {
  50         erst_get_record_id_end();
  51
  52         return 0;
  53 }
  54
  55 static long erst_dbg_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
  56 {
  57         int rc;
  58         u64 record_id;
  59         u32 record_count;
  60
  61         switch (cmd) {
  62         case APEI_ERST_CLEAR_RECORD:
  63                 rc = copy_from_user(&record_id, (void __user *)arg,
  64                                     sizeof(record_id));
  65                 if (rc)
  66                         return -EFAULT;
  67                 return erst_clear(record_id);
  68         case APEI_ERST_GET_RECORD_COUNT:
  69                 rc = erst_get_record_count();
  70                 if (rc < 0)
  71                         return rc;
  72                 record_count = rc;
  73                 rc = put_user(record_count, (u32 __user *)arg);
  74                 if (rc)
  75                         return rc;
  76                 return 0;
  77         default:
  78                 return -ENOTTY;
  79         }
  80 }
  81
  82 static ssize_t erst_dbg_read(struct file *filp, char __user *ubuf,
  83                              size_t usize, loff_t *off)
  84 {
  85         int rc, *pos;
  86         ssize_t len = 0;
  87         u64 id;
  88
  89         if (*off)
  90                 return -EINVAL;
  91
  92         if (mutex_lock_interruptible(&erst_dbg_mutex) != 0)
  93                 return -EINTR;
  94
  95         pos = (int *)&filp->private_data;
  96
  97 retry_next:
  98         rc = erst_get_record_id_next(pos, &id);
  99         if (rc)
 100                 goto out;
 101         /* no more record */
 102         if (id == APEI_ERST_INVALID_RECORD_ID) {
 103                 /*
 104                  * If the persistent store is empty initially, the function
 105                  * 'erst_read' below will return "-ENOENT" value. This causes
 106                  * 'retry_next' label is entered again. The returned value
 107                  * should be zero indicating the read operation is EOF.
 108                  */
 109                 len = 0;
 110
 111                 goto out;
 112         }
 113 retry:
 114         rc = len = erst_read(id, erst_dbg_buf, erst_dbg_buf_len);
 115         /* The record may be cleared by others, try read next record */
 116         if (rc == -ENOENT)
 117                 goto retry_next;
 118         if (rc < 0)
 119                 goto out;
 120         if (len > ERST_DBG_RECORD_LEN_MAX) {
 121                 pr_warn(ERST_DBG_PFX
 122                         "Record (ID: 0x%llx) length is too long: %zd\n", id, len);
 123                 rc = -EIO;
 124                 goto out;
 125         }
 126         if (len > erst_dbg_buf_len) {
 127                 void *p;
 128                 rc = -ENOMEM;
 129                 p = kmalloc(len, GFP_KERNEL);
 130                 if (!p)
 131                         goto out;
 132                 kfree(erst_dbg_buf);
 133                 erst_dbg_buf = p;
 134                 erst_dbg_buf_len = len;
 135                 goto retry;
 136         }
 137
 138         rc = -EINVAL;
 139         if (len > usize)
 140                 goto out;
 141
 142         rc = -EFAULT;
 143         if (copy_to_user(ubuf, erst_dbg_buf, len))
 144                 goto out;
 145         rc = 0;
 146 out:
 147         mutex_unlock(&erst_dbg_mutex);
 148         return rc ? rc : len;
 149 }
 150
 151 static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf,
 152                               size_t usize, loff_t *off)
 153 {
 154         int rc;
 155         struct cper_record_header *rcd;
 156
 157         if (!capable(CAP_SYS_ADMIN))
 158                 return -EPERM;
 159
 160         if (usize > ERST_DBG_RECORD_LEN_MAX) {
 161                 pr_err(ERST_DBG_PFX "Too long record to be written\n");
 162                 return -EINVAL;
 163         }
 164
 165         if (mutex_lock_interruptible(&erst_dbg_mutex))
 166                 return -EINTR;
 167         if (usize > erst_dbg_buf_len) {
 168                 void *p;
 169                 rc = -ENOMEM;
 170                 p = kmalloc(usize, GFP_KERNEL);
 171                 if (!p)
 172                         goto out;
 173                 kfree(erst_dbg_buf);
 174                 erst_dbg_buf = p;
 175                 erst_dbg_buf_len = usize;
 176         }
 177         rc = copy_from_user(erst_dbg_buf, ubuf, usize);
 178         if (rc) {
 179                 rc = -EFAULT;
 180                 goto out;
 181         }
 182         rcd = erst_dbg_buf;
 183         rc = -EINVAL;
 184         if (rcd->record_length != usize)
 185                 goto out;
 186
 187         rc = erst_write(erst_dbg_buf);
 188
 189 out:
 190         mutex_unlock(&erst_dbg_mutex);
 191         return rc < 0 ? rc : usize;
 192 }
 193
 194 static const struct file_operations erst_dbg_ops = {
 195         .owner          = THIS_MODULE,
 196         .open           = erst_dbg_open,
 197         .release        = erst_dbg_release,
 198         .read           = erst_dbg_read,
 199         .write          = erst_dbg_write,
 200         .unlocked_ioctl = erst_dbg_ioctl,
 201         .llseek         = no_llseek,
 202 };
 203
 204 static struct miscdevice erst_dbg_dev = {
 205         .minor  = MISC_DYNAMIC_MINOR,
 206         .name   = "erst_dbg",
 207         .fops   = &erst_dbg_ops,
 208 };
 209
 210 static __init int erst_dbg_init(void)
 211 {
 212         if (erst_disable) {
 213                 pr_info(ERST_DBG_PFX "ERST support is disabled.\n");
 214                 return -ENODEV;
 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");