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
26static void *erst_dbg_buf;
27static unsigned int erst_dbg_buf_len;
28
29/* Prevent erst_dbg_read/write from being invoked concurrently */
30static DEFINE_MUTEX(erst_dbg_mutex);
31
32static 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, filp: file);
46}
47
48static int erst_dbg_release(struct inode *inode, struct file *file)
49{
50 erst_get_record_id_end();
51
52 return 0;
53}
54
55static 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(to: &record_id, from: (void __user *)arg,
64 n: 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
82static 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
97retry_next:
98 rc = erst_get_record_id_next(pos, record_id: &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 }
113retry:
114 rc = len = erst_read_record(record_id: id, record: erst_dbg_buf, buflen: erst_dbg_buf_len,
115 recordlen: 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(size: len, GFP_KERNEL);
131 if (!p)
132 goto out;
133 kfree(objp: 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(to: ubuf, from: erst_dbg_buf, n: len))
145 goto out;
146 rc = 0;
147out:
148 mutex_unlock(lock: &erst_dbg_mutex);
149 return rc ? rc : len;
150}
151
152static 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(size: usize, GFP_KERNEL);
172 if (!p)
173 goto out;
174 kfree(objp: erst_dbg_buf);
175 erst_dbg_buf = p;
176 erst_dbg_buf_len = usize;
177 }
178 rc = copy_from_user(to: erst_dbg_buf, from: ubuf, n: 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(record: erst_dbg_buf);
189
190out:
191 mutex_unlock(lock: &erst_dbg_mutex);
192 return rc < 0 ? rc : usize;
193}
194
195static 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
205static struct miscdevice erst_dbg_dev = {
206 .minor = MISC_DYNAMIC_MINOR,
207 .name = "erst_dbg",
208 .fops = &erst_dbg_ops,
209};
210
211static __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(misc: &erst_dbg_dev);
218}
219
220static __exit void erst_dbg_exit(void)
221{
222 misc_deregister(misc: &erst_dbg_dev);
223 kfree(objp: erst_dbg_buf);
224}
225
226module_init(erst_dbg_init);
227module_exit(erst_dbg_exit);
228
229MODULE_AUTHOR("Huang Ying");
230MODULE_DESCRIPTION("APEI Error Record Serialization Table debug support");
231MODULE_LICENSE("GPL");
232

source code of linux/drivers/acpi/apei/erst-dbg.c