1/*
2 * APEI Error Record Serialization Table debug support
3 *
4 * ERST is a way provided by APEI to save and retrieve hardware error
5 * information to and from a persistent store. This file provide the
6 * debugging/testing support for ERST kernel support and firmware
7 * implementation.
8 *
9 * Copyright 2010 Intel Corp.
10 *   Author: Huang Ying <ying.huang@intel.com>
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License version
14 * 2 as published by the Free Software Foundation.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
24 */
25
26#include <linux/kernel.h>
27#include <linux/module.h>
28#include <linux/uaccess.h>
29#include <acpi/apei.h>
30#include <linux/miscdevice.h>
31
32#include "apei-internal.h"
33
34#define ERST_DBG_PFX			"ERST DBG: "
35
36#define ERST_DBG_RECORD_LEN_MAX		0x4000
37
38static void *erst_dbg_buf;
39static unsigned int erst_dbg_buf_len;
40
41/* Prevent erst_dbg_read/write from being invoked concurrently */
42static DEFINE_MUTEX(erst_dbg_mutex);
43
44static int erst_dbg_open(struct inode *inode, struct file *file)
45{
46	int rc, *pos;
47
48	if (erst_disable)
49		return -ENODEV;
50
51	pos = (int *)&file->private_data;
52
53	rc = erst_get_record_id_begin(pos);
54	if (rc)
55		return rc;
56
57	return nonseekable_open(inode, file);
58}
59
60static int erst_dbg_release(struct inode *inode, struct file *file)
61{
62	erst_get_record_id_end();
63
64	return 0;
65}
66
67static long erst_dbg_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
68{
69	int rc;
70	u64 record_id;
71	u32 record_count;
72
73	switch (cmd) {
74	case APEI_ERST_CLEAR_RECORD:
75		rc = copy_from_user(&record_id, (void __user *)arg,
76				    sizeof(record_id));
77		if (rc)
78			return -EFAULT;
79		return erst_clear(record_id);
80	case APEI_ERST_GET_RECORD_COUNT:
81		rc = erst_get_record_count();
82		if (rc < 0)
83			return rc;
84		record_count = rc;
85		rc = put_user(record_count, (u32 __user *)arg);
86		if (rc)
87			return rc;
88		return 0;
89	default:
90		return -ENOTTY;
91	}
92}
93
94static ssize_t erst_dbg_read(struct file *filp, char __user *ubuf,
95			     size_t usize, loff_t *off)
96{
97	int rc, *pos;
98	ssize_t len = 0;
99	u64 id;
100
101	if (*off)
102		return -EINVAL;
103
104	if (mutex_lock_interruptible(&erst_dbg_mutex) != 0)
105		return -EINTR;
106
107	pos = (int *)&filp->private_data;
108
109retry_next:
110	rc = erst_get_record_id_next(pos, &id);
111	if (rc)
112		goto out;
113	/* no more record */
114	if (id == APEI_ERST_INVALID_RECORD_ID) {
115		/*
116		 * If the persistent store is empty initially, the function
117		 * 'erst_read' below will return "-ENOENT" value. This causes
118		 * 'retry_next' label is entered again. The returned value
119		 * should be zero indicating the read operation is EOF.
120		 */
121		len = 0;
122
123		goto out;
124	}
125retry:
126	rc = len = erst_read(id, erst_dbg_buf, erst_dbg_buf_len);
127	/* The record may be cleared by others, try read next record */
128	if (rc == -ENOENT)
129		goto retry_next;
130	if (rc < 0)
131		goto out;
132	if (len > ERST_DBG_RECORD_LEN_MAX) {
133		pr_warning(ERST_DBG_PFX
134			   "Record (ID: 0x%llx) length is too long: %zd\n",
135			   id, len);
136		rc = -EIO;
137		goto out;
138	}
139	if (len > erst_dbg_buf_len) {
140		void *p;
141		rc = -ENOMEM;
142		p = kmalloc(len, GFP_KERNEL);
143		if (!p)
144			goto out;
145		kfree(erst_dbg_buf);
146		erst_dbg_buf = p;
147		erst_dbg_buf_len = len;
148		goto retry;
149	}
150
151	rc = -EINVAL;
152	if (len > usize)
153		goto out;
154
155	rc = -EFAULT;
156	if (copy_to_user(ubuf, erst_dbg_buf, len))
157		goto out;
158	rc = 0;
159out:
160	mutex_unlock(&erst_dbg_mutex);
161	return rc ? rc : len;
162}
163
164static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf,
165			      size_t usize, loff_t *off)
166{
167	int rc;
168	struct cper_record_header *rcd;
169
170	if (!capable(CAP_SYS_ADMIN))
171		return -EPERM;
172
173	if (usize > ERST_DBG_RECORD_LEN_MAX) {
174		pr_err(ERST_DBG_PFX "Too long record to be written\n");
175		return -EINVAL;
176	}
177
178	if (mutex_lock_interruptible(&erst_dbg_mutex))
179		return -EINTR;
180	if (usize > erst_dbg_buf_len) {
181		void *p;
182		rc = -ENOMEM;
183		p = kmalloc(usize, GFP_KERNEL);
184		if (!p)
185			goto out;
186		kfree(erst_dbg_buf);
187		erst_dbg_buf = p;
188		erst_dbg_buf_len = usize;
189	}
190	rc = copy_from_user(erst_dbg_buf, ubuf, usize);
191	if (rc) {
192		rc = -EFAULT;
193		goto out;
194	}
195	rcd = erst_dbg_buf;
196	rc = -EINVAL;
197	if (rcd->record_length != usize)
198		goto out;
199
200	rc = erst_write(erst_dbg_buf);
201
202out:
203	mutex_unlock(&erst_dbg_mutex);
204	return rc < 0 ? rc : usize;
205}
206
207static const struct file_operations erst_dbg_ops = {
208	.owner		= THIS_MODULE,
209	.open		= erst_dbg_open,
210	.release	= erst_dbg_release,
211	.read		= erst_dbg_read,
212	.write		= erst_dbg_write,
213	.unlocked_ioctl	= erst_dbg_ioctl,
214	.llseek		= no_llseek,
215};
216
217static struct miscdevice erst_dbg_dev = {
218	.minor	= MISC_DYNAMIC_MINOR,
219	.name	= "erst_dbg",
220	.fops	= &erst_dbg_ops,
221};
222
223static __init int erst_dbg_init(void)
224{
225	if (erst_disable) {
226		pr_info(ERST_DBG_PFX "ERST support is disabled.\n");
227		return -ENODEV;
228	}
229	return misc_register(&erst_dbg_dev);
230}
231
232static __exit void erst_dbg_exit(void)
233{
234	misc_deregister(&erst_dbg_dev);
235	kfree(erst_dbg_buf);
236}
237
238module_init(erst_dbg_init);
239module_exit(erst_dbg_exit);
240
241MODULE_AUTHOR("Huang Ying");
242MODULE_DESCRIPTION("APEI Error Record Serialization Table debug support");
243MODULE_LICENSE("GPL");
244