[PATCH] s390: use __cpcmd in vmcp_write
[linux-2.6.git] / drivers / s390 / char / vmcp.c
1 /*
2  * Copyright (C) 2004,2005 IBM Corporation
3  * Interface implementation for communication with the v/VM control program
4  * Author(s): Christian Borntraeger <cborntra@de.ibm.com>
5  *
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/module.h>
19 #include <asm/cpcmd.h>
20 #include <asm/debug.h>
21 #include <asm/uaccess.h>
22 #include "vmcp.h"
23
24 MODULE_LICENSE("GPL");
25 MODULE_AUTHOR("Christian Borntraeger <cborntra@de.ibm.com>");
26 MODULE_DESCRIPTION("z/VM CP interface");
27
28 static debug_info_t *vmcp_debug;
29
30 static int vmcp_open(struct inode *inode, struct file *file)
31 {
32         struct vmcp_session *session;
33
34         if (!capable(CAP_SYS_ADMIN))
35                 return -EPERM;
36
37         session = kmalloc(sizeof(*session), GFP_KERNEL);
38         if (!session)
39                 return -ENOMEM;
40         session->bufsize = PAGE_SIZE;
41         session->response = NULL;
42         session->resp_size = 0;
43         init_MUTEX(&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 = (struct vmcp_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         size_t tocopy;
63         struct vmcp_session *session;
64
65         session = (struct vmcp_session *)file->private_data;
66         if (down_interruptible(&session->mutex))
67                 return -ERESTARTSYS;
68         if (!session->response) {
69                 up(&session->mutex);
70                 return 0;
71         }
72         if (*ppos > session->resp_size) {
73                 up(&session->mutex);
74                 return 0;
75         }
76         tocopy = min(session->resp_size - (size_t) (*ppos), count);
77         tocopy = min(tocopy,session->bufsize - (size_t) (*ppos));
78
79         if (copy_to_user(buff, session->response + (*ppos), tocopy)) {
80                 up(&session->mutex);
81                 return -EFAULT;
82         }
83         up(&session->mutex);
84         *ppos += tocopy;
85         return tocopy;
86 }
87
88 static ssize_t
89 vmcp_write(struct file *file, const char __user * buff, size_t count,
90            loff_t * ppos)
91 {
92         char *cmd;
93         struct vmcp_session *session;
94
95         if (count > 240)
96                 return -EINVAL;
97         cmd = kmalloc(count + 1, GFP_KERNEL);
98         if (!cmd)
99                 return -ENOMEM;
100         if (copy_from_user(cmd, buff, count)) {
101                 kfree(cmd);
102                 return -EFAULT;
103         }
104         cmd[count] = '\0';
105         session = (struct vmcp_session *)file->private_data;
106         if (down_interruptible(&session->mutex))
107                 return -ERESTARTSYS;
108         if (!session->response)
109                 session->response = (char *)__get_free_pages(GFP_KERNEL
110                                                 | __GFP_REPEAT  | GFP_DMA,
111                                                 get_order(session->bufsize));
112         if (!session->response) {
113                 up(&session->mutex);
114                 kfree(cmd);
115                 return -ENOMEM;
116         }
117         debug_text_event(vmcp_debug, 1, cmd);
118         session->resp_size = __cpcmd(cmd, session->response,
119                                      session->bufsize,
120                                      &session->resp_code);
121         up(&session->mutex);
122         kfree(cmd);
123         *ppos = 0;              /* reset the file pointer after a command */
124         return count;
125 }
126
127
128 /*
129  * These ioctls are available, as the semantics of the diagnose 8 call
130  * does not fit very well into a Linux call. Diagnose X'08' is described in
131  * CP Programming Services SC24-6084-00
132  *
133  * VMCP_GETCODE: gives the CP return code back to user space
134  * VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8
135  * expects adjacent pages in real storage and to make matters worse, we
136  * dont know the size of the response. Therefore we default to PAGESIZE and
137  * let userspace to change the response size, if userspace expects a bigger
138  * response
139  */
140 static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
141 {
142         struct vmcp_session *session;
143         int temp;
144
145         session = (struct vmcp_session *)file->private_data;
146         if (down_interruptible(&session->mutex))
147                 return -ERESTARTSYS;
148         switch (cmd) {
149         case VMCP_GETCODE:
150                 temp = session->resp_code;
151                 up(&session->mutex);
152                 return put_user(temp, (int __user *)arg);
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, (int __user *)arg);
158                 if (get_order(session->bufsize) > 8) {
159                         session->bufsize = PAGE_SIZE;
160                         temp = -EINVAL;
161                 }
162                 up(&session->mutex);
163                 return temp;
164         case VMCP_GETSIZE:
165                 temp = session->resp_size;
166                 up(&session->mutex);
167                 return put_user(temp, (int __user *)arg);
168         default:
169                 up(&session->mutex);
170                 return -ENOIOCTLCMD;
171         }
172 }
173
174 static struct file_operations vmcp_fops = {
175         .owner          = THIS_MODULE,
176         .open           = &vmcp_open,
177         .release        = &vmcp_release,
178         .read           = &vmcp_read,
179         .llseek         = &no_llseek,
180         .write          = &vmcp_write,
181         .unlocked_ioctl = &vmcp_ioctl,
182         .compat_ioctl   = &vmcp_ioctl
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                 printk(KERN_WARNING
197                        "z/VM CP interface is only available under z/VM\n");
198                 return -ENODEV;
199         }
200         ret = misc_register(&vmcp_dev);
201         if (!ret)
202                 printk(KERN_INFO "z/VM CP interface loaded\n");
203         else
204                 printk(KERN_WARNING
205                        "z/VM CP interface not loaded. Could not register misc device.\n");
206         vmcp_debug = debug_register("vmcp", 1, 1, 240);
207         debug_register_view(vmcp_debug, &debug_hex_ascii_view);
208         return ret;
209 }
210
211 static void __exit vmcp_exit(void)
212 {
213         WARN_ON(misc_deregister(&vmcp_dev) != 0);
214         debug_unregister(vmcp_debug);
215         printk(KERN_INFO "z/VM CP interface unloaded.\n");
216 }
217
218 module_init(vmcp_init);
219 module_exit(vmcp_exit);