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		goto out;
116retry:
117	rc = len = erst_read(id, erst_dbg_buf, erst_dbg_buf_len);
118	/* The record may be cleared by others, try read next record */
119	if (rc == -ENOENT)
120		goto retry_next;
121	if (rc < 0)
122		goto out;
123	if (len > ERST_DBG_RECORD_LEN_MAX) {
124		pr_warning(ERST_DBG_PFX
125			   "Record (ID: 0x%llx) length is too long: %zd\n",
126			   id, len);
127		rc = -EIO;
128		goto out;
129	}
130	if (len > erst_dbg_buf_len) {
131		void *p;
132		rc = -ENOMEM;
133		p = kmalloc(len, GFP_KERNEL);
134		if (!p)
135			goto out;
136		kfree(erst_dbg_buf);
137		erst_dbg_buf = p;
138		erst_dbg_buf_len = len;
139		goto retry;
140	}
141
142	rc = -EINVAL;
143	if (len > usize)
144		goto out;
145
146	rc = -EFAULT;
147	if (copy_to_user(ubuf, erst_dbg_buf, len))
148		goto out;
149	rc = 0;
150out:
151	mutex_unlock(&erst_dbg_mutex);
152	return rc ? rc : len;
153}
154
155static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf,
156			      size_t usize, loff_t *off)
157{
158	int rc;
159	struct cper_record_header *rcd;
160
161	if (!capable(CAP_SYS_ADMIN))
162		return -EPERM;
163
164	if (usize > ERST_DBG_RECORD_LEN_MAX) {
165		pr_err(ERST_DBG_PFX "Too long record to be written\n");
166		return -EINVAL;
167	}
168
169	if (mutex_lock_interruptible(&erst_dbg_mutex))
170		return -EINTR;
171	if (usize > erst_dbg_buf_len) {
172		void *p;
173		rc = -ENOMEM;
174		p = kmalloc(usize, GFP_KERNEL);
175		if (!p)
176			goto out;
177		kfree(erst_dbg_buf);
178		erst_dbg_buf = p;
179		erst_dbg_buf_len = usize;
180	}
181	rc = copy_from_user(erst_dbg_buf, ubuf, usize);
182	if (rc) {
183		rc = -EFAULT;
184		goto out;
185	}
186	rcd = erst_dbg_buf;
187	rc = -EINVAL;
188	if (rcd->record_length != usize)
189		goto out;
190
191	rc = erst_write(erst_dbg_buf);
192
193out:
194	mutex_unlock(&erst_dbg_mutex);
195	return rc < 0 ? rc : usize;
196}
197
198static const struct file_operations erst_dbg_ops = {
199	.owner		= THIS_MODULE,
200	.open		= erst_dbg_open,
201	.release	= erst_dbg_release,
202	.read		= erst_dbg_read,
203	.write		= erst_dbg_write,
204	.unlocked_ioctl	= erst_dbg_ioctl,
205	.llseek		= no_llseek,
206};
207
208static struct miscdevice erst_dbg_dev = {
209	.minor	= MISC_DYNAMIC_MINOR,
210	.name	= "erst_dbg",
211	.fops	= &erst_dbg_ops,
212};
213
214static __init int erst_dbg_init(void)
215{
216	if (erst_disable) {
217		pr_info(ERST_DBG_PFX "ERST support is disabled.\n");
218		return -ENODEV;
219	}
220	return misc_register(&erst_dbg_dev);
221}
222
223static __exit void erst_dbg_exit(void)
224{
225	misc_deregister(&erst_dbg_dev);
226	kfree(erst_dbg_buf);
227}
228
229module_init(erst_dbg_init);
230module_exit(erst_dbg_exit);
231
232MODULE_AUTHOR("Huang Ying");
233MODULE_DESCRIPTION("APEI Error Record Serialization Table debug support");
234MODULE_LICENSE("GPL");
235