1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
|
/* Copyright (C) 2005 - 2008 Jeff Dike <jdike@{linux.intel,addtoit}.com> */
/* Much of this ripped from drivers/char/hw_random.c, see there for other
* copyright.
*
* This software may be used and distributed according to the terms
* of the GNU General Public License, incorporated herein by reference.
*/
#include <linux/sched/signal.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/miscdevice.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include <irq_kern.h>
#include <os.h>
/*
* core module and version information
*/
#define RNG_VERSION "1.0.0"
#define RNG_MODULE_NAME "hw_random"
#define RNG_MISCDEV_MINOR 183 /* official */
/* Changed at init time, in the non-modular case, and at module load
* time, in the module case. Presumably, the module subsystem
* protects against a module being loaded twice at the same time.
*/
static int random_fd = -1;
static DECLARE_WAIT_QUEUE_HEAD(host_read_wait);
static int rng_dev_open (struct inode *inode, struct file *filp)
{
/* enforce read-only access to this chrdev */
if ((filp->f_mode & FMODE_READ) == 0)
return -EINVAL;
if ((filp->f_mode & FMODE_WRITE) != 0)
return -EINVAL;
return 0;
}
static atomic_t host_sleep_count = ATOMIC_INIT(0);
static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size,
loff_t *offp)
{
u32 data;
int n, ret = 0, have_data;
while (size) {
n = os_read_file(random_fd, &data, sizeof(data));
if (n > 0) {
have_data = n;
while (have_data && size) {
if (put_user((u8) data, buf++)) {
ret = ret ? : -EFAULT;
break;
}
size--;
ret++;
have_data--;
data >>= 8;
}
}
else if (n == -EAGAIN) {
DECLARE_WAITQUEUE(wait, current);
if (filp->f_flags & O_NONBLOCK)
return ret ? : -EAGAIN;
atomic_inc(&host_sleep_count);
reactivate_fd(random_fd, RANDOM_IRQ);
add_sigio_fd(random_fd);
add_wait_queue(&host_read_wait, &wait);
set_current_state(TASK_INTERRUPTIBLE);
schedule();
remove_wait_queue(&host_read_wait, &wait);
if (atomic_dec_and_test(&host_sleep_count)) {
ignore_sigio_fd(random_fd);
deactivate_fd(random_fd, RANDOM_IRQ);
}
}
else
return n;
if (signal_pending (current))
return ret ? : -ERESTARTSYS;
}
return ret;
}
static const struct file_operations rng_chrdev_ops = {
.owner = THIS_MODULE,
.open = rng_dev_open,
.read = rng_dev_read,
.llseek = noop_llseek,
};
/* rng_init shouldn't be called more than once at boot time */
static struct miscdevice rng_miscdev = {
RNG_MISCDEV_MINOR,
RNG_MODULE_NAME,
&rng_chrdev_ops,
};
static irqreturn_t random_interrupt(int irq, void *data)
{
wake_up(&host_read_wait);
return IRQ_HANDLED;
}
/*
* rng_init - initialize RNG module
*/
static int __init rng_init (void)
{
int err;
err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0);
if (err < 0)
goto out;
random_fd = err;
err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt,
0, "random", NULL);
if (err)
goto err_out_cleanup_hw;
sigio_broken(random_fd, 1);
err = misc_register (&rng_miscdev);
if (err) {
printk (KERN_ERR RNG_MODULE_NAME ": misc device register "
"failed\n");
goto err_out_cleanup_hw;
}
out:
return err;
err_out_cleanup_hw:
os_close_file(random_fd);
random_fd = -1;
goto out;
}
/*
* rng_cleanup - shutdown RNG module
*/
static void __exit rng_cleanup (void)
{
os_close_file(random_fd);
misc_deregister (&rng_miscdev);
}
module_init (rng_init);
module_exit (rng_cleanup);
MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver");
MODULE_LICENSE("GPL");
|
