summaryrefslogtreecommitdiffstats
path: root/drivers/s390/char/vmcp.c
blob: af616aeaa9380c28abdb05b1399398d63ffb4843 (plain)
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
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
/*
 * Copyright IBM Corp. 2004,2007
 * Interface implementation for communication with the z/VM control program
 * Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
 *
 *
 * z/VMs CP offers the possibility to issue commands via the diagnose code 8
 * this driver implements a character device that issues these commands and
 * returns the answer of CP.

 * The idea of this driver is based on cpint from Neale Ferguson and #CP in CMS
 */

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <asm/cpcmd.h>
#include <asm/debug.h>
#include <asm/uaccess.h>
#include "vmcp.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Borntraeger <borntraeger@de.ibm.com>");
MODULE_DESCRIPTION("z/VM CP interface");

#define PRINTK_HEADER "vmcp: "

static debug_info_t *vmcp_debug;

static int vmcp_open(struct inode *inode, struct file *file)
{
	struct vmcp_session *session;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	session = kmalloc(sizeof(*session), GFP_KERNEL);
	if (!session)
		return -ENOMEM;
	session->bufsize = PAGE_SIZE;
	session->response = NULL;
	session->resp_size = 0;
	mutex_init(&session->mutex);
	file->private_data = session;
	return nonseekable_open(inode, file);
}

static int vmcp_release(struct inode *inode, struct file *file)
{
	struct vmcp_session *session;

	session = (struct vmcp_session *)file->private_data;
	file->private_data = NULL;
	free_pages((unsigned long)session->response, get_order(session->bufsize));
	kfree(session);
	return 0;
}

static ssize_t
vmcp_read(struct file *file, char __user *buff, size_t count, loff_t *ppos)
{
	ssize_t ret;
	size_t size;
	struct vmcp_session *session;

	session = file->private_data;
	if (mutex_lock_interruptible(&session->mutex))
		return -ERESTARTSYS;
	if (!session->response) {
		mutex_unlock(&session->mutex);
		return 0;
	}
	size = min_t(size_t, session->resp_size, session->bufsize);
	ret = simple_read_from_buffer(buff, count, ppos,
					session->response, size);

	mutex_unlock(&session->mutex);

	return ret;
}

static ssize_t
vmcp_write(struct file *file, const char __user *buff, size_t count,
	   loff_t *ppos)
{
	char *cmd;
	struct vmcp_session *session;

	if (count > 240)
		return -EINVAL;
	cmd = kmalloc(count + 1, GFP_KERNEL);
	if (!cmd)
		return -ENOMEM;
	if (copy_from_user(cmd, buff, count)) {
		kfree(cmd);
		return -EFAULT;
	}
	cmd[count] = '\0';
	session = (struct vmcp_session *)file->private_data;
	if (mutex_lock_interruptible(&session->mutex)) {
		kfree(cmd);
		return -ERESTARTSYS;
	}
	if (!session->response)
		session->response = (char *)__get_free_pages(GFP_KERNEL
						| __GFP_REPEAT | GFP_DMA,
						get_order(session->bufsize));
	if (!session->response) {
		mutex_unlock(&session->mutex);
		kfree(cmd);
		return -ENOMEM;
	}
	debug_text_event(vmcp_debug, 1, cmd);
	session->resp_size = cpcmd(cmd, session->response, session->bufsize,
				   &session->resp_code);
	mutex_unlock(&session->mutex);
	kfree(cmd);
	*ppos = 0;		/* reset the file pointer after a command */
	return count;
}


/*
 * These ioctls are available, as the semantics of the diagnose 8 call
 * does not fit very well into a Linux call. Diagnose X'08' is described in
 * CP Programming Services SC24-6084-00
 *
 * VMCP_GETCODE: gives the CP return code back to user space
 * VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8
 * expects adjacent pages in real storage and to make matters worse, we
 * dont know the size of the response. Therefore we default to PAGESIZE and
 * let userspace to change the response size, if userspace expects a bigger
 * response
 */
static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct vmcp_session *session;
	int temp;

	session = (struct vmcp_session *)file->private_data;
	if (mutex_lock_interruptible(&session->mutex))
		return -ERESTARTSYS;
	switch (cmd) {
	case VMCP_GETCODE:
		temp = session->resp_code;
		mutex_unlock(&session->mutex);
		return put_user(temp, (int __user *)arg);
	case VMCP_SETBUF:
		free_pages((unsigned long)session->response,
				get_order(session->bufsize));
		session->response=NULL;
		temp = get_user(session->bufsize, (int __user *)arg);
		if (get_order(session->bufsize) > 8) {
			session->bufsize = PAGE_SIZE;
			temp = -EINVAL;
		}
		mutex_unlock(&session->mutex);
		return temp;
	case VMCP_GETSIZE:
		temp = session->resp_size;
		mutex_unlock(&session->mutex);
		return put_user(temp, (int __user *)arg);
	default:
		mutex_unlock(&session->mutex);
		return -ENOIOCTLCMD;
	}
}

static const struct file_operations vmcp_fops = {
	.owner		= THIS_MODULE,
	.open		= vmcp_open,
	.release	= vmcp_release,
	.read		= vmcp_read,
	.write		= vmcp_write,
	.unlocked_ioctl	= vmcp_ioctl,
	.compat_ioctl	= vmcp_ioctl,
};

static struct miscdevice vmcp_dev = {
	.name	= "vmcp",
	.minor	= MISC_DYNAMIC_MINOR,
	.fops	= &vmcp_fops,
};

static int __init vmcp_init(void)
{
	int ret;

	if (!MACHINE_IS_VM) {
		PRINT_WARN("z/VM CP interface is only available under z/VM\n");
		return -ENODEV;
	}
	vmcp_debug = debug_register("vmcp", 1, 1, 240);
	if (!vmcp_debug) {
		PRINT_ERR("z/VM CP interface not loaded. Could not register "
			   "debug feature\n");
		return -ENOMEM;
	}
	ret = debug_register_view(vmcp_debug, &debug_hex_ascii_view);
	if (ret) {
		PRINT_ERR("z/VM CP interface not loaded. Could not register "
			  "debug feature view. Error code: %d\n", ret);
		debug_unregister(vmcp_debug);
		return ret;
	}
	ret = misc_register(&vmcp_dev);
	if (ret) {
		PRINT_ERR("z/VM CP interface not loaded. Could not register "
			   "misc device. Error code: %d\n", ret);
		debug_unregister(vmcp_debug);
		return ret;
	}
	PRINT_INFO("z/VM CP interface loaded\n");
	return 0;
}

static void __exit vmcp_exit(void)
{
	misc_deregister(&vmcp_dev);
	debug_unregister(vmcp_debug);
	PRINT_INFO("z/VM CP interface unloaded.\n");
}

module_init(vmcp_init);
module_exit(vmcp_exit);