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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); | |
22 | #define PMSG_MAX_BOUNCE_BUFFER_SIZE (2*PAGE_SIZE) | |
23 | ||
24 | static ssize_t write_pmsg(struct file *file, const char __user *buf, | |
25 | size_t count, loff_t *ppos) | |
26 | { | |
27 | size_t i, buffer_size; | |
28 | char *buffer; | |
29 | ||
30 | if (!count) | |
31 | return 0; | |
32 | ||
33 | if (!access_ok(VERIFY_READ, buf, count)) | |
34 | return -EFAULT; | |
35 | ||
36 | buffer_size = count; | |
37 | if (buffer_size > PMSG_MAX_BOUNCE_BUFFER_SIZE) | |
38 | buffer_size = PMSG_MAX_BOUNCE_BUFFER_SIZE; | |
39 | buffer = vmalloc(buffer_size); | |
40 | ||
41 | mutex_lock(&pmsg_lock); | |
42 | for (i = 0; i < count; ) { | |
43 | size_t c = min(count - i, buffer_size); | |
44 | u64 id; | |
45 | long ret; | |
46 | ||
47 | ret = __copy_from_user(buffer, buf + i, c); | |
48 | if (unlikely(ret != 0)) { | |
49 | mutex_unlock(&pmsg_lock); | |
50 | vfree(buffer); | |
51 | return -EFAULT; | |
52 | } | |
53 | psinfo->write_buf(PSTORE_TYPE_PMSG, 0, &id, 0, buffer, 0, c, | |
54 | psinfo); | |
55 | ||
56 | i += c; | |
57 | } | |
58 | ||
59 | mutex_unlock(&pmsg_lock); | |
60 | vfree(buffer); | |
61 | return count; | |
62 | } | |
63 | ||
64 | static const struct file_operations pmsg_fops = { | |
65 | .owner = THIS_MODULE, | |
66 | .llseek = noop_llseek, | |
67 | .write = write_pmsg, | |
68 | }; | |
69 | ||
70 | static struct class *pmsg_class; | |
71 | static int pmsg_major; | |
72 | #define PMSG_NAME "pmsg" | |
73 | #undef pr_fmt | |
74 | #define pr_fmt(fmt) PMSG_NAME ": " fmt | |
75 | ||
76 | static char *pmsg_devnode(struct device *dev, umode_t *mode) | |
77 | { | |
78 | if (mode) | |
79 | *mode = 0220; | |
80 | return NULL; | |
81 | } | |
82 | ||
83 | void pstore_register_pmsg(void) | |
84 | { | |
85 | struct device *pmsg_device; | |
86 | ||
87 | pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops); | |
88 | if (pmsg_major < 0) { | |
89 | pr_err("register_chrdev failed\n"); | |
90 | goto err; | |
91 | } | |
92 | ||
93 | pmsg_class = class_create(THIS_MODULE, PMSG_NAME); | |
94 | if (IS_ERR(pmsg_class)) { | |
95 | pr_err("device class file already in use\n"); | |
96 | goto err_class; | |
97 | } | |
98 | pmsg_class->devnode = pmsg_devnode; | |
99 | ||
100 | pmsg_device = device_create(pmsg_class, NULL, MKDEV(pmsg_major, 0), | |
101 | NULL, "%s%d", PMSG_NAME, 0); | |
102 | if (IS_ERR(pmsg_device)) { | |
103 | pr_err("failed to create device\n"); | |
104 | goto err_device; | |
105 | } | |
106 | return; | |
107 | ||
108 | err_device: | |
109 | class_destroy(pmsg_class); | |
110 | err_class: | |
111 | unregister_chrdev(pmsg_major, PMSG_NAME); | |
112 | err: | |
113 | return; | |
114 | } |