compat: fix compile breakage on s390
[linux-2.6.git] / drivers / s390 / char / vmcp.c
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/compat.h>
17 #include <linux/kernel.h>
18 #include <linux/miscdevice.h>
19 #include <linux/slab.h>
20 #include <linux/export.h>
21 #include <asm/compat.h>
22 #include <asm/cpcmd.h>
23 #include <asm/debug.h>
24 #include <asm/uaccess.h>
25 #include "vmcp.h"
26
27 static debug_info_t *vmcp_debug;
28
29 static int vmcp_open(struct inode *inode, struct file *file)
30 {
31         struct vmcp_session *session;
32
33         if (!capable(CAP_SYS_ADMIN))
34                 return -EPERM;
35
36         session = kmalloc(sizeof(*session), GFP_KERNEL);
37         if (!session)
38                 return -ENOMEM;
39
40         session->bufsize = PAGE_SIZE;
41         session->response = NULL;
42         session->resp_size = 0;
43         mutex_init(&session->mutex);
44         file->private_data = session;
45         return nonseekable_open(inode, file);
46 }
47
48 static int vmcp_release(struct inode *inode, struct file *file)
49 {
50         struct vmcp_session *session;
51
52         session = file->private_data;
53         file->private_data = NULL;
54         free_pages((unsigned long)session->response, get_order(session->bufsize));
55         kfree(session);
56         return 0;
57 }
58
59 static ssize_t
60 vmcp_read(struct file *file, char __user *buff, size_t count, loff_t *ppos)
61 {
62         ssize_t ret;
63         size_t size;
64         struct vmcp_session *session;
65
66         session = file->private_data;
67         if (mutex_lock_interruptible(&session->mutex))
68                 return -ERESTARTSYS;
69         if (!session->response) {
70                 mutex_unlock(&session->mutex);
71                 return 0;
72         }
73         size = min_t(size_t, session->resp_size, session->bufsize);
74         ret = simple_read_from_buffer(buff, count, ppos,
75                                         session->response, size);
76
77         mutex_unlock(&session->mutex);
78
79         return ret;
80 }
81
82 static ssize_t
83 vmcp_write(struct file *file, const char __user *buff, size_t count,
84            loff_t *ppos)
85 {
86         char *cmd;
87         struct vmcp_session *session;
88
89         if (count > 240)
90                 return -EINVAL;
91         cmd = kmalloc(count + 1, GFP_KERNEL);
92         if (!cmd)
93                 return -ENOMEM;
94         if (copy_from_user(cmd, buff, count)) {
95                 kfree(cmd);
96                 return -EFAULT;
97         }
98         cmd[count] = '\0';
99         session = file->private_data;
100         if (mutex_lock_interruptible(&session->mutex)) {
101                 kfree(cmd);
102                 return -ERESTARTSYS;
103         }
104         if (!session->response)
105                 session->response = (char *)__get_free_pages(GFP_KERNEL
106                                                 | __GFP_REPEAT | GFP_DMA,
107                                                 get_order(session->bufsize));
108         if (!session->response) {
109                 mutex_unlock(&session->mutex);
110                 kfree(cmd);
111                 return -ENOMEM;
112         }
113         debug_text_event(vmcp_debug, 1, cmd);
114         session->resp_size = cpcmd(cmd, session->response, session->bufsize,
115                                    &session->resp_code);
116         mutex_unlock(&session->mutex);
117         kfree(cmd);
118         *ppos = 0;              /* reset the file pointer after a command */
119         return count;
120 }
121
122
123 /*
124  * These ioctls are available, as the semantics of the diagnose 8 call
125  * does not fit very well into a Linux call. Diagnose X'08' is described in
126  * CP Programming Services SC24-6084-00
127  *
128  * VMCP_GETCODE: gives the CP return code back to user space
129  * VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8
130  * expects adjacent pages in real storage and to make matters worse, we
131  * dont know the size of the response. Therefore we default to PAGESIZE and
132  * let userspace to change the response size, if userspace expects a bigger
133  * response
134  */
135 static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
136 {
137         struct vmcp_session *session;
138         int __user *argp;
139         int temp;
140
141         session = file->private_data;
142         if (is_compat_task())
143                 argp = compat_ptr(arg);
144         else
145                 argp = (int __user *)arg;
146         if (mutex_lock_interruptible(&session->mutex))
147                 return -ERESTARTSYS;
148         switch (cmd) {
149         case VMCP_GETCODE:
150                 temp = session->resp_code;
151                 mutex_unlock(&session->mutex);
152                 return put_user(temp, argp);
153         case VMCP_SETBUF:
154                 free_pages((unsigned long)session->response,
155                                 get_order(session->bufsize));
156                 session->response=NULL;
157                 temp = get_user(session->bufsize, argp);
158                 if (get_order(session->bufsize) > 8) {
159                         session->bufsize = PAGE_SIZE;
160                         temp = -EINVAL;
161                 }
162                 mutex_unlock(&session->mutex);
163                 return temp;
164         case VMCP_GETSIZE:
165                 temp = session->resp_size;
166                 mutex_unlock(&session->mutex);
167                 return put_user(temp, argp);
168         default:
169                 mutex_unlock(&session->mutex);
170                 return -ENOIOCTLCMD;
171         }
172 }
173
174 static const struct file_operations vmcp_fops = {
175         .owner          = THIS_MODULE,
176         .open           = vmcp_open,
177         .release        = vmcp_release,
178         .read           = vmcp_read,
179         .write          = vmcp_write,
180         .unlocked_ioctl = vmcp_ioctl,
181         .compat_ioctl   = vmcp_ioctl,
182         .llseek         = no_llseek,
183 };
184
185 static struct miscdevice vmcp_dev = {
186         .name   = "vmcp",
187         .minor  = MISC_DYNAMIC_MINOR,
188         .fops   = &vmcp_fops,
189 };
190
191 static int __init vmcp_init(void)
192 {
193         int ret;
194
195         if (!MACHINE_IS_VM)
196                 return 0;
197
198         vmcp_debug = debug_register("vmcp", 1, 1, 240);
199         if (!vmcp_debug)
200                 return -ENOMEM;
201
202         ret = debug_register_view(vmcp_debug, &debug_hex_ascii_view);
203         if (ret) {
204                 debug_unregister(vmcp_debug);
205                 return ret;
206         }
207
208         ret = misc_register(&vmcp_dev);
209         if (ret)
210                 debug_unregister(vmcp_debug);
211         return ret;
212 }
213 device_initcall(vmcp_init);