x86/CPU/AMD: Update the Zenbleed microcode revisions
[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_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");