Merge tag 'wireless-drivers-2019-12-17' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6-microblaze.git] / 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");