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 0x4000 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 /* 116 * If the persistent store is empty initially, the function 117 * 'erst_read' below will return "-ENOENT" value. This causes 118 * 'retry_next' label is entered again. The returned value 119 * should be zero indicating the read operation is EOF. 120 */ 121 len = 0; 122 123 goto out; 124 } 125 retry: 126 rc = len = erst_read(id, erst_dbg_buf, erst_dbg_buf_len); 127 /* The record may be cleared by others, try read next record */ 128 if (rc == -ENOENT) 129 goto retry_next; 130 if (rc < 0) 131 goto out; 132 if (len > ERST_DBG_RECORD_LEN_MAX) { 133 pr_warning(ERST_DBG_PFX 134 "Record (ID: 0x%llx) length is too long: %zd\n", 135 id, len); 136 rc = -EIO; 137 goto out; 138 } 139 if (len > erst_dbg_buf_len) { 140 void *p; 141 rc = -ENOMEM; 142 p = kmalloc(len, GFP_KERNEL); 143 if (!p) 144 goto out; 145 kfree(erst_dbg_buf); 146 erst_dbg_buf = p; 147 erst_dbg_buf_len = len; 148 goto retry; 149 } 150 151 rc = -EINVAL; 152 if (len > usize) 153 goto out; 154 155 rc = -EFAULT; 156 if (copy_to_user(ubuf, erst_dbg_buf, len)) 157 goto out; 158 rc = 0; 159 out: 160 mutex_unlock(&erst_dbg_mutex); 161 return rc ? rc : len; 162 } 163 164 static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf, 165 size_t usize, loff_t *off) 166 { 167 int rc; 168 struct cper_record_header *rcd; 169 170 if (!capable(CAP_SYS_ADMIN)) 171 return -EPERM; 172 173 if (usize > ERST_DBG_RECORD_LEN_MAX) { 174 pr_err(ERST_DBG_PFX "Too long record to be written\n"); 175 return -EINVAL; 176 } 177 178 if (mutex_lock_interruptible(&erst_dbg_mutex)) 179 return -EINTR; 180 if (usize > erst_dbg_buf_len) { 181 void *p; 182 rc = -ENOMEM; 183 p = kmalloc(usize, GFP_KERNEL); 184 if (!p) 185 goto out; 186 kfree(erst_dbg_buf); 187 erst_dbg_buf = p; 188 erst_dbg_buf_len = usize; 189 } 190 rc = copy_from_user(erst_dbg_buf, ubuf, usize); 191 if (rc) { 192 rc = -EFAULT; 193 goto out; 194 } 195 rcd = erst_dbg_buf; 196 rc = -EINVAL; 197 if (rcd->record_length != usize) 198 goto out; 199 200 rc = erst_write(erst_dbg_buf); 201 202 out: 203 mutex_unlock(&erst_dbg_mutex); 204 return rc < 0 ? rc : usize; 205 } 206 207 static const struct file_operations erst_dbg_ops = { 208 .owner = THIS_MODULE, 209 .open = erst_dbg_open, 210 .release = erst_dbg_release, 211 .read = erst_dbg_read, 212 .write = erst_dbg_write, 213 .unlocked_ioctl = erst_dbg_ioctl, 214 .llseek = no_llseek, 215 }; 216 217 static struct miscdevice erst_dbg_dev = { 218 .minor = MISC_DYNAMIC_MINOR, 219 .name = "erst_dbg", 220 .fops = &erst_dbg_ops, 221 }; 222 223 static __init int erst_dbg_init(void) 224 { 225 if (erst_disable) { 226 pr_info(ERST_DBG_PFX "ERST support is disabled.\n"); 227 return -ENODEV; 228 } 229 return misc_register(&erst_dbg_dev); 230 } 231 232 static __exit void erst_dbg_exit(void) 233 { 234 misc_deregister(&erst_dbg_dev); 235 kfree(erst_dbg_buf); 236 } 237 238 module_init(erst_dbg_init); 239 module_exit(erst_dbg_exit); 240 241 MODULE_AUTHOR("Huang Ying"); 242 MODULE_DESCRIPTION("APEI Error Record Serialization Table debug support"); 243 MODULE_LICENSE("GPL"); 244