1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright 2014 Google, Inc.
4 */
5
6 #include <linux/cdev.h>
7 #include <linux/device.h>
8 #include <linux/fs.h>
9 #include <linux/uaccess.h>
10 #include "internal.h"
11
12 static DEFINE_MUTEX(pmsg_lock);
13
14 static ssize_t write_pmsg(struct file *file, const char __user *buf,
15 size_t count, loff_t *ppos)
16 {
17 struct pstore_record record;
18 int ret;
19
20 if (!count)
21 return 0;
22
23 pstore_record_init(&record, psinfo);
24 record.type = PSTORE_TYPE_PMSG;
25 record.size = count;
26
27 /* check outside lock, page in any data. write_user also checks */
28 if (!access_ok(buf, count))
29 return -EFAULT;
30
31 mutex_lock(&pmsg_lock);
32 ret = psinfo->write_user(&record, buf);
33 mutex_unlock(&pmsg_lock);
34 return ret ? ret : count;
35 }
36
37 static const struct file_operations pmsg_fops = {
38 .owner = THIS_MODULE,
39 .llseek = noop_llseek,
40 .write = write_pmsg,
41 };
42
43 static struct class *pmsg_class;
44 static int pmsg_major;
45 #define PMSG_NAME "pmsg"
46 #undef pr_fmt
47 #define pr_fmt(fmt) PMSG_NAME ": " fmt
48
49 static char *pmsg_devnode(const struct device *dev, umode_t *mode)
50 {
51 if (mode)
52 *mode = 0220;
53 return NULL;
54 }
55
56 void pstore_register_pmsg(void)
57 {
58 struct device *pmsg_device;
59
60 pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops);
61 if (pmsg_major < 0) {
62 pr_err("register_chrdev failed\n");
63 goto err;
64 }
65
66 pmsg_class = class_create(PMSG_NAME);
67 if (IS_ERR(pmsg_class)) {
68 pr_err("device class file already in use\n");
69 goto err_class;
70 }
71 pmsg_class->devnode = pmsg_devnode;
72
73 pmsg_device = device_create(pmsg_class, NULL, MKDEV(pmsg_major, 0),
74 NULL, "%s%d", PMSG_NAME, 0);
75 if (IS_ERR(pmsg_device)) {
76 pr_err("failed to create device\n");
77 goto err_device;
78 }
79 return;
80
81 err_device:
82 class_destroy(pmsg_class);
83 err_class:
84 unregister_chrdev(pmsg_major, PMSG_NAME);
85 err:
86 return;
87 }
88
89 void pstore_unregister_pmsg(void)
90 {
91 device_destroy(pmsg_class, MKDEV(pmsg_major, 0));
92 class_destroy(pmsg_class);
93 unregister_chrdev(pmsg_major, PMSG_NAME);
94 }
95
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