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
12static DEFINE_MUTEX(pmsg_lock);
13
14static 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
37static const struct file_operations pmsg_fops = {
38 .owner = THIS_MODULE,
39 .llseek = noop_llseek,
40 .write = write_pmsg,
41};
42
43static struct class *pmsg_class;
44static int pmsg_major;
45#define PMSG_NAME "pmsg"
46#undef pr_fmt
47#define pr_fmt(fmt) PMSG_NAME ": " fmt
48
49static char *pmsg_devnode(const struct device *dev, umode_t *mode)
50{
51 if (mode)
52 *mode = 0220;
53 return NULL;
54}
55
56void 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
81err_device:
82 class_destroy(cls: pmsg_class);
83err_class:
84 unregister_chrdev(major: pmsg_major, PMSG_NAME);
85err:
86 return;
87}
88
89void 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

source code of linux/fs/pstore/pmsg.c