xref: /openbmc/linux/drivers/acpi/apei/erst-dbg.c (revision a0909315)
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_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 
erst_dbg_write(struct file * filp,const char __user * ubuf,size_t usize,loff_t * off)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 
erst_dbg_init(void)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 
erst_dbg_exit(void)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");
232