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);