1 /*
2 * Copyright IBM Corp. 2004,2010
3 * Interface implementation for communication with the z/VM control program
4 *
5 * Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
6 *
7 * z/VMs CP offers the possibility to issue commands via the diagnose code 8
8 * this driver implements a character device that issues these commands and
9 * returns the answer of CP.
10 *
11 * The idea of this driver is based on cpint from Neale Ferguson and #CP in CMS
12 */
13
14 #include <linux/fs.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/miscdevice.h>
18 #include <linux/slab.h>
19 #include <asm/compat.h>
20 #include <asm/cpcmd.h>
21 #include <asm/debug.h>
22 #include <asm/uaccess.h>
23 #include "vmcp.h"
24
25 static debug_info_t *vmcp_debug;
26
vmcp_open(struct inode * inode,struct file * file)27 static int vmcp_open(struct inode *inode, struct file *file)
28 {
29 struct vmcp_session *session;
30
31 if (!capable(CAP_SYS_ADMIN))
32 return -EPERM;
33
34 session = kmalloc(sizeof(*session), GFP_KERNEL);
35 if (!session)
36 return -ENOMEM;
37
38 session->bufsize = PAGE_SIZE;
39 session->response = NULL;
40 session->resp_size = 0;
41 mutex_init(&session->mutex);
42 file->private_data = session;
43 return nonseekable_open(inode, file);
44 }
45
vmcp_release(struct inode * inode,struct file * file)46 static int vmcp_release(struct inode *inode, struct file *file)
47 {
48 struct vmcp_session *session;
49
50 session = file->private_data;
51 file->private_data = NULL;
52 free_pages((unsigned long)session->response, get_order(session->bufsize));
53 kfree(session);
54 return 0;
55 }
56
57 static ssize_t
vmcp_read(struct file * file,char __user * buff,size_t count,loff_t * ppos)58 vmcp_read(struct file *file, char __user *buff, size_t count, loff_t *ppos)
59 {
60 ssize_t ret;
61 size_t size;
62 struct vmcp_session *session;
63
64 session = file->private_data;
65 if (mutex_lock_interruptible(&session->mutex))
66 return -ERESTARTSYS;
67 if (!session->response) {
68 mutex_unlock(&session->mutex);
69 return 0;
70 }
71 size = min_t(size_t, session->resp_size, session->bufsize);
72 ret = simple_read_from_buffer(buff, count, ppos,
73 session->response, size);
74
75 mutex_unlock(&session->mutex);
76
77 return ret;
78 }
79
80 static ssize_t
vmcp_write(struct file * file,const char __user * buff,size_t count,loff_t * ppos)81 vmcp_write(struct file *file, const char __user *buff, size_t count,
82 loff_t *ppos)
83 {
84 char *cmd;
85 struct vmcp_session *session;
86
87 if (count > 240)
88 return -EINVAL;
89 cmd = kmalloc(count + 1, GFP_KERNEL);
90 if (!cmd)
91 return -ENOMEM;
92 if (copy_from_user(cmd, buff, count)) {
93 kfree(cmd);
94 return -EFAULT;
95 }
96 cmd[count] = '\0';
97 session = file->private_data;
98 if (mutex_lock_interruptible(&session->mutex)) {
99 kfree(cmd);
100 return -ERESTARTSYS;
101 }
102 if (!session->response)
103 session->response = (char *)__get_free_pages(GFP_KERNEL
104 | __GFP_REPEAT | GFP_DMA,
105 get_order(session->bufsize));
106 if (!session->response) {
107 mutex_unlock(&session->mutex);
108 kfree(cmd);
109 return -ENOMEM;
110 }
111 debug_text_event(vmcp_debug, 1, cmd);
112 session->resp_size = cpcmd(cmd, session->response, session->bufsize,
113 &session->resp_code);
114 mutex_unlock(&session->mutex);
115 kfree(cmd);
116 *ppos = 0; /* reset the file pointer after a command */
117 return count;
118 }
119
120
121 /*
122 * These ioctls are available, as the semantics of the diagnose 8 call
123 * does not fit very well into a Linux call. Diagnose X'08' is described in
124 * CP Programming Services SC24-6084-00
125 *
126 * VMCP_GETCODE: gives the CP return code back to user space
127 * VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8
128 * expects adjacent pages in real storage and to make matters worse, we
129 * dont know the size of the response. Therefore we default to PAGESIZE and
130 * let userspace to change the response size, if userspace expects a bigger
131 * response
132 */
vmcp_ioctl(struct file * file,unsigned int cmd,unsigned long arg)133 static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
134 {
135 struct vmcp_session *session;
136 int __user *argp;
137 int temp;
138
139 session = file->private_data;
140 if (is_compat_task())
141 argp = compat_ptr(arg);
142 else
143 argp = (int __user *)arg;
144 if (mutex_lock_interruptible(&session->mutex))
145 return -ERESTARTSYS;
146 switch (cmd) {
147 case VMCP_GETCODE:
148 temp = session->resp_code;
149 mutex_unlock(&session->mutex);
150 return put_user(temp, argp);
151 case VMCP_SETBUF:
152 free_pages((unsigned long)session->response,
153 get_order(session->bufsize));
154 session->response=NULL;
155 temp = get_user(session->bufsize, argp);
156 if (get_order(session->bufsize) > 8) {
157 session->bufsize = PAGE_SIZE;
158 temp = -EINVAL;
159 }
160 mutex_unlock(&session->mutex);
161 return temp;
162 case VMCP_GETSIZE:
163 temp = session->resp_size;
164 mutex_unlock(&session->mutex);
165 return put_user(temp, argp);
166 default:
167 mutex_unlock(&session->mutex);
168 return -ENOIOCTLCMD;
169 }
170 }
171
172 static const struct file_operations vmcp_fops = {
173 .owner = THIS_MODULE,
174 .open = vmcp_open,
175 .release = vmcp_release,
176 .read = vmcp_read,
177 .write = vmcp_write,
178 .unlocked_ioctl = vmcp_ioctl,
179 .compat_ioctl = vmcp_ioctl,
180 .llseek = no_llseek,
181 };
182
183 static struct miscdevice vmcp_dev = {
184 .name = "vmcp",
185 .minor = MISC_DYNAMIC_MINOR,
186 .fops = &vmcp_fops,
187 };
188
vmcp_init(void)189 static int __init vmcp_init(void)
190 {
191 int ret;
192
193 if (!MACHINE_IS_VM)
194 return 0;
195
196 vmcp_debug = debug_register("vmcp", 1, 1, 240);
197 if (!vmcp_debug)
198 return -ENOMEM;
199
200 ret = debug_register_view(vmcp_debug, &debug_hex_ascii_view);
201 if (ret) {
202 debug_unregister(vmcp_debug);
203 return ret;
204 }
205
206 ret = misc_register(&vmcp_dev);
207 if (ret)
208 debug_unregister(vmcp_debug);
209 return ret;
210 }
211 device_initcall(vmcp_init);
212