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
erst_dbg_open(struct inode * inode,struct file * file)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
erst_dbg_release(struct inode * inode,struct file * file)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
erst_dbg_ioctl(struct file * f,unsigned int cmd,unsigned long arg)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
erst_dbg_read(struct file * filp,char __user * ubuf,size_t usize,loff_t * off)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
erst_dbg_write(struct file * filp,const char __user * ubuf,size_t usize,loff_t * off)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
erst_dbg_init(void)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
erst_dbg_exit(void)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");
231