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: &record, psi: 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(lock: &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(major: 0, PMSG_NAME, fops: &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(ptr: 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(cls: pmsg_class, NULL, MKDEV(pmsg_major, 0), |
74 | NULL, fmt: "%s%d" , PMSG_NAME, 0); |
75 | if (IS_ERR(ptr: pmsg_device)) { |
76 | pr_err("failed to create device\n" ); |
77 | goto err_device; |
78 | } |
79 | return; |
80 | |
81 | err_device: |
82 | class_destroy(cls: pmsg_class); |
83 | err_class: |
84 | unregister_chrdev(major: pmsg_major, PMSG_NAME); |
85 | err: |
86 | return; |
87 | } |
88 | |
89 | void pstore_unregister_pmsg(void) |
90 | { |
91 | device_destroy(cls: pmsg_class, MKDEV(pmsg_major, 0)); |
92 | class_destroy(cls: pmsg_class); |
93 | unregister_chrdev(major: pmsg_major, PMSG_NAME); |
94 | } |
95 | |