mm, page_alloc: set alloc_flags only once in slowpath
[linux/fpc-iii.git] / drivers / acpi / apei / erst-dbg.c
blob6330f557a2c8856b3a18a13fa851b1cb64af3b4f
1 /*
2 * APEI Error Record Serialization Table debug support
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.
9 * Copyright 2010 Intel Corp.
10 * Author: Huang Ying <ying.huang@intel.com>
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.
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.
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/uaccess.h>
25 #include <acpi/apei.h>
26 #include <linux/miscdevice.h>
28 #include "apei-internal.h"
30 #define ERST_DBG_PFX "ERST DBG: "
32 #define ERST_DBG_RECORD_LEN_MAX 0x4000
34 static void *erst_dbg_buf;
35 static unsigned int erst_dbg_buf_len;
37 /* Prevent erst_dbg_read/write from being invoked concurrently */
38 static DEFINE_MUTEX(erst_dbg_mutex);
40 static int erst_dbg_open(struct inode *inode, struct file *file)
42 int rc, *pos;
44 if (erst_disable)
45 return -ENODEV;
47 pos = (int *)&file->private_data;
49 rc = erst_get_record_id_begin(pos);
50 if (rc)
51 return rc;
53 return nonseekable_open(inode, file);
56 static int erst_dbg_release(struct inode *inode, struct file *file)
58 erst_get_record_id_end();
60 return 0;
63 static long erst_dbg_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
65 int rc;
66 u64 record_id;
67 u32 record_count;
69 switch (cmd) {
70 case APEI_ERST_CLEAR_RECORD:
71 rc = copy_from_user(&record_id, (void __user *)arg,
72 sizeof(record_id));
73 if (rc)
74 return -EFAULT;
75 return erst_clear(record_id);
76 case APEI_ERST_GET_RECORD_COUNT:
77 rc = erst_get_record_count();
78 if (rc < 0)
79 return rc;
80 record_count = rc;
81 rc = put_user(record_count, (u32 __user *)arg);
82 if (rc)
83 return rc;
84 return 0;
85 default:
86 return -ENOTTY;
90 static ssize_t erst_dbg_read(struct file *filp, char __user *ubuf,
91 size_t usize, loff_t *off)
93 int rc, *pos;
94 ssize_t len = 0;
95 u64 id;
97 if (*off)
98 return -EINVAL;
100 if (mutex_lock_interruptible(&erst_dbg_mutex) != 0)
101 return -EINTR;
103 pos = (int *)&filp->private_data;
105 retry_next:
106 rc = erst_get_record_id_next(pos, &id);
107 if (rc)
108 goto out;
109 /* no more record */
110 if (id == APEI_ERST_INVALID_RECORD_ID) {
112 * If the persistent store is empty initially, the function
113 * 'erst_read' below will return "-ENOENT" value. This causes
114 * 'retry_next' label is entered again. The returned value
115 * should be zero indicating the read operation is EOF.
117 len = 0;
119 goto out;
121 retry:
122 rc = len = erst_read(id, erst_dbg_buf, erst_dbg_buf_len);
123 /* The record may be cleared by others, try read next record */
124 if (rc == -ENOENT)
125 goto retry_next;
126 if (rc < 0)
127 goto out;
128 if (len > ERST_DBG_RECORD_LEN_MAX) {
129 pr_warning(ERST_DBG_PFX
130 "Record (ID: 0x%llx) length is too long: %zd\n",
131 id, len);
132 rc = -EIO;
133 goto out;
135 if (len > erst_dbg_buf_len) {
136 void *p;
137 rc = -ENOMEM;
138 p = kmalloc(len, GFP_KERNEL);
139 if (!p)
140 goto out;
141 kfree(erst_dbg_buf);
142 erst_dbg_buf = p;
143 erst_dbg_buf_len = len;
144 goto retry;
147 rc = -EINVAL;
148 if (len > usize)
149 goto out;
151 rc = -EFAULT;
152 if (copy_to_user(ubuf, erst_dbg_buf, len))
153 goto out;
154 rc = 0;
155 out:
156 mutex_unlock(&erst_dbg_mutex);
157 return rc ? rc : len;
160 static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf,
161 size_t usize, loff_t *off)
163 int rc;
164 struct cper_record_header *rcd;
166 if (!capable(CAP_SYS_ADMIN))
167 return -EPERM;
169 if (usize > ERST_DBG_RECORD_LEN_MAX) {
170 pr_err(ERST_DBG_PFX "Too long record to be written\n");
171 return -EINVAL;
174 if (mutex_lock_interruptible(&erst_dbg_mutex))
175 return -EINTR;
176 if (usize > erst_dbg_buf_len) {
177 void *p;
178 rc = -ENOMEM;
179 p = kmalloc(usize, GFP_KERNEL);
180 if (!p)
181 goto out;
182 kfree(erst_dbg_buf);
183 erst_dbg_buf = p;
184 erst_dbg_buf_len = usize;
186 rc = copy_from_user(erst_dbg_buf, ubuf, usize);
187 if (rc) {
188 rc = -EFAULT;
189 goto out;
191 rcd = erst_dbg_buf;
192 rc = -EINVAL;
193 if (rcd->record_length != usize)
194 goto out;
196 rc = erst_write(erst_dbg_buf);
198 out:
199 mutex_unlock(&erst_dbg_mutex);
200 return rc < 0 ? rc : usize;
203 static const struct file_operations erst_dbg_ops = {
204 .owner = THIS_MODULE,
205 .open = erst_dbg_open,
206 .release = erst_dbg_release,
207 .read = erst_dbg_read,
208 .write = erst_dbg_write,
209 .unlocked_ioctl = erst_dbg_ioctl,
210 .llseek = no_llseek,
213 static struct miscdevice erst_dbg_dev = {
214 .minor = MISC_DYNAMIC_MINOR,
215 .name = "erst_dbg",
216 .fops = &erst_dbg_ops,
219 static __init int erst_dbg_init(void)
221 if (erst_disable) {
222 pr_info(ERST_DBG_PFX "ERST support is disabled.\n");
223 return -ENODEV;
225 return misc_register(&erst_dbg_dev);
228 static __exit void erst_dbg_exit(void)
230 misc_deregister(&erst_dbg_dev);
231 kfree(erst_dbg_buf);
234 module_init(erst_dbg_init);
235 module_exit(erst_dbg_exit);
237 MODULE_AUTHOR("Huang Ying");
238 MODULE_DESCRIPTION("APEI Error Record Serialization Table debug support");
239 MODULE_LICENSE("GPL");