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9d5438f4 MS |
1 | /* |
2 | * Copyright 2014 Google, Inc. | |
3 | * | |
4 | * This software is licensed under the terms of the GNU General Public | |
5 | * License version 2, as published by the Free Software Foundation, and | |
6 | * may be copied, distributed, and modified under those terms. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, | |
9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
11 | * GNU General Public License for more details. | |
12 | */ | |
13 | ||
14 | #include <linux/cdev.h> | |
15 | #include <linux/device.h> | |
16 | #include <linux/fs.h> | |
17 | #include <linux/uaccess.h> | |
18 | #include <linux/vmalloc.h> | |
19 | #include "internal.h" | |
20 | ||
21 | static DEFINE_MUTEX(pmsg_lock); | |
9d5438f4 MS |
22 | |
23 | static ssize_t write_pmsg(struct file *file, const char __user *buf, | |
24 | size_t count, loff_t *ppos) | |
25 | { | |
5bf6d1b9 MS |
26 | u64 id; |
27 | int ret; | |
9d5438f4 MS |
28 | |
29 | if (!count) | |
30 | return 0; | |
31 | ||
5bf6d1b9 | 32 | /* check outside lock, page in any data. write_buf_user also checks */ |
9d5438f4 MS |
33 | if (!access_ok(VERIFY_READ, buf, count)) |
34 | return -EFAULT; | |
35 | ||
9d5438f4 | 36 | mutex_lock(&pmsg_lock); |
5bf6d1b9 MS |
37 | ret = psinfo->write_buf_user(PSTORE_TYPE_PMSG, 0, &id, 0, buf, 0, count, |
38 | psinfo); | |
9d5438f4 | 39 | mutex_unlock(&pmsg_lock); |
5bf6d1b9 | 40 | return ret ? ret : count; |
9d5438f4 MS |
41 | } |
42 | ||
43 | static const struct file_operations pmsg_fops = { | |
44 | .owner = THIS_MODULE, | |
45 | .llseek = noop_llseek, | |
46 | .write = write_pmsg, | |
47 | }; | |
48 | ||
49 | static struct class *pmsg_class; | |
50 | static int pmsg_major; | |
51 | #define PMSG_NAME "pmsg" | |
52 | #undef pr_fmt | |
53 | #define pr_fmt(fmt) PMSG_NAME ": " fmt | |
54 | ||
55 | static char *pmsg_devnode(struct device *dev, umode_t *mode) | |
56 | { | |
57 | if (mode) | |
58 | *mode = 0220; | |
59 | return NULL; | |
60 | } | |
61 | ||
62 | void pstore_register_pmsg(void) | |
63 | { | |
64 | struct device *pmsg_device; | |
65 | ||
66 | pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops); | |
67 | if (pmsg_major < 0) { | |
68 | pr_err("register_chrdev failed\n"); | |
69 | goto err; | |
70 | } | |
71 | ||
72 | pmsg_class = class_create(THIS_MODULE, PMSG_NAME); | |
73 | if (IS_ERR(pmsg_class)) { | |
74 | pr_err("device class file already in use\n"); | |
75 | goto err_class; | |
76 | } | |
77 | pmsg_class->devnode = pmsg_devnode; | |
78 | ||
79 | pmsg_device = device_create(pmsg_class, NULL, MKDEV(pmsg_major, 0), | |
80 | NULL, "%s%d", PMSG_NAME, 0); | |
81 | if (IS_ERR(pmsg_device)) { | |
82 | pr_err("failed to create device\n"); | |
83 | goto err_device; | |
84 | } | |
85 | return; | |
86 | ||
87 | err_device: | |
88 | class_destroy(pmsg_class); | |
89 | err_class: | |
90 | unregister_chrdev(pmsg_major, PMSG_NAME); | |
91 | err: | |
92 | return; | |
93 | } | |
ee1d2674 GT |
94 | |
95 | void pstore_unregister_pmsg(void) | |
96 | { | |
97 | device_destroy(pmsg_class, MKDEV(pmsg_major, 0)); | |
98 | class_destroy(pmsg_class); | |
99 | unregister_chrdev(pmsg_major, PMSG_NAME); | |
100 | } |