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_record(id, erst_dbg_buf, erst_dbg_buf_len,
 115                         erst_dbg_buf_len, NULL);
 116         /* The record may be cleared by others, try read next record */
 117         if (rc == -ENOENT)
 118                 goto retry_next;
 119         if (rc < 0)
 120                 goto out;
 121         if (len > ERST_DBG_RECORD_LEN_MAX) {
 122                 pr_warn(ERST_DBG_PFX
 123                         "Record (ID: 0x%llx) length is too long: %zd\n", id, len);
 124                 rc = -EIO;
 125                 goto out;
 126         }
 127         if (len > erst_dbg_buf_len) {
 128                 void *p;
 129                 rc = -ENOMEM;
 130                 p = kmalloc(len, GFP_KERNEL);
 131                 if (!p)
 132                         goto out;
 133                 kfree(erst_dbg_buf);
 134                 erst_dbg_buf = p;
 135                 erst_dbg_buf_len = len;
 136                 goto retry;
 137         }
 138
 139         rc = -EINVAL;
 140         if (len > usize)
 141                 goto out;
 142
 143         rc = -EFAULT;
 144         if (copy_to_user(ubuf, erst_dbg_buf, len))
 145                 goto out;
 146         rc = 0;
 147 out:
 148         mutex_unlock(&erst_dbg_mutex);
 149         return rc ? rc : len;
 150 }
 151
 152 static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf,
 153                               size_t usize, loff_t *off)
 154 {
 155         int rc;
 156         struct cper_record_header *rcd;
 157
 158         if (!capable(CAP_SYS_ADMIN))
 159                 return -EPERM;
 160
 161         if (usize > ERST_DBG_RECORD_LEN_MAX) {
 162                 pr_err(ERST_DBG_PFX "Too long record to be written\n");
 163                 return -EINVAL;
 164         }
 165
 166         if (mutex_lock_interruptible(&erst_dbg_mutex))
 167                 return -EINTR;
 168         if (usize > erst_dbg_buf_len) {
 169                 void *p;
 170                 rc = -ENOMEM;
 171                 p = kmalloc(usize, GFP_KERNEL);
 172                 if (!p)
 173                         goto out;
 174                 kfree(erst_dbg_buf);
 175                 erst_dbg_buf = p;
 176                 erst_dbg_buf_len = usize;
 177         }
 178         rc = copy_from_user(erst_dbg_buf, ubuf, usize);
 179         if (rc) {
 180                 rc = -EFAULT;
 181                 goto out;
 182         }
 183         rcd = erst_dbg_buf;
 184         rc = -EINVAL;
 185         if (rcd->record_length != usize)
 186                 goto out;
 187
 188         rc = erst_write(erst_dbg_buf);
 189
 190 out:
 191         mutex_unlock(&erst_dbg_mutex);
 192         return rc < 0 ? rc : usize;
 193 }
 194
 195 static const struct file_operations erst_dbg_ops = {
 196         .owner          = THIS_MODULE,
 197         .open           = erst_dbg_open,
 198         .release        = erst_dbg_release,
 199         .read           = erst_dbg_read,
 200         .write          = erst_dbg_write,
 201         .unlocked_ioctl = erst_dbg_ioctl,
 202         .llseek         = no_llseek,
 203 };
 204
 205 static struct miscdevice erst_dbg_dev = {
 206         .minor  = MISC_DYNAMIC_MINOR,
 207         .name   = "erst_dbg",
 208         .fops   = &erst_dbg_ops,
 209 };
 210
 211 static __init int erst_dbg_init(void)
 212 {
 213         if (erst_disable) {
 214                 pr_info(ERST_DBG_PFX "ERST support is disabled.\n");
 215                 return -ENODEV;
 216         }
 217         return misc_register(&erst_dbg_dev);
 218 }
 219
 220 static __exit void erst_dbg_exit(void)
 221 {
 222         misc_deregister(&erst_dbg_dev);
 223         kfree(erst_dbg_buf);
 224 }
 225
 226 module_init(erst_dbg_init);
 227 module_exit(erst_dbg_exit);
 228
 229 MODULE_AUTHOR("Huang Ying");
 230 MODULE_DESCRIPTION("APEI Error Record Serialization Table debug support");
 231 MODULE_LICENSE("GPL");