1 /* 2 * Copyright (C) 2004,2005 IBM Corporation 3 * Interface implementation for communication with the z/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 kfree(cmd); 108 return -ERESTARTSYS; 109 } 110 if (!session->response) 111 session->response = (char *)__get_free_pages(GFP_KERNEL 112 | __GFP_REPEAT | GFP_DMA, 113 get_order(session->bufsize)); 114 if (!session->response) { 115 up(&session->mutex); 116 kfree(cmd); 117 return -ENOMEM; 118 } 119 debug_text_event(vmcp_debug, 1, cmd); 120 session->resp_size = __cpcmd(cmd, session->response, 121 session->bufsize, 122 &session->resp_code); 123 up(&session->mutex); 124 kfree(cmd); 125 *ppos = 0; /* reset the file pointer after a command */ 126 return count; 127 } 128 129 130 /* 131 * These ioctls are available, as the semantics of the diagnose 8 call 132 * does not fit very well into a Linux call. Diagnose X'08' is described in 133 * CP Programming Services SC24-6084-00 134 * 135 * VMCP_GETCODE: gives the CP return code back to user space 136 * VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8 137 * expects adjacent pages in real storage and to make matters worse, we 138 * dont know the size of the response. Therefore we default to PAGESIZE and 139 * let userspace to change the response size, if userspace expects a bigger 140 * response 141 */ 142 static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 143 { 144 struct vmcp_session *session; 145 int temp; 146 147 session = (struct vmcp_session *)file->private_data; 148 if (down_interruptible(&session->mutex)) 149 return -ERESTARTSYS; 150 switch (cmd) { 151 case VMCP_GETCODE: 152 temp = session->resp_code; 153 up(&session->mutex); 154 return put_user(temp, (int __user *)arg); 155 case VMCP_SETBUF: 156 free_pages((unsigned long)session->response, 157 get_order(session->bufsize)); 158 session->response=NULL; 159 temp = get_user(session->bufsize, (int __user *)arg); 160 if (get_order(session->bufsize) > 8) { 161 session->bufsize = PAGE_SIZE; 162 temp = -EINVAL; 163 } 164 up(&session->mutex); 165 return temp; 166 case VMCP_GETSIZE: 167 temp = session->resp_size; 168 up(&session->mutex); 169 return put_user(temp, (int __user *)arg); 170 default: 171 up(&session->mutex); 172 return -ENOIOCTLCMD; 173 } 174 } 175 176 static struct file_operations vmcp_fops = { 177 .owner = THIS_MODULE, 178 .open = &vmcp_open, 179 .release = &vmcp_release, 180 .read = &vmcp_read, 181 .llseek = &no_llseek, 182 .write = &vmcp_write, 183 .unlocked_ioctl = &vmcp_ioctl, 184 .compat_ioctl = &vmcp_ioctl 185 }; 186 187 static struct miscdevice vmcp_dev = { 188 .name = "vmcp", 189 .minor = MISC_DYNAMIC_MINOR, 190 .fops = &vmcp_fops, 191 }; 192 193 static int __init vmcp_init(void) 194 { 195 int ret; 196 197 if (!MACHINE_IS_VM) { 198 printk(KERN_WARNING 199 "z/VM CP interface is only available under z/VM\n"); 200 return -ENODEV; 201 } 202 ret = misc_register(&vmcp_dev); 203 if (!ret) 204 printk(KERN_INFO "z/VM CP interface loaded\n"); 205 else 206 printk(KERN_WARNING 207 "z/VM CP interface not loaded. Could not register misc device.\n"); 208 vmcp_debug = debug_register("vmcp", 1, 1, 240); 209 debug_register_view(vmcp_debug, &debug_hex_ascii_view); 210 return ret; 211 } 212 213 static void __exit vmcp_exit(void) 214 { 215 WARN_ON(misc_deregister(&vmcp_dev) != 0); 216 debug_unregister(vmcp_debug); 217 printk(KERN_INFO "z/VM CP interface unloaded.\n"); 218 } 219 220 module_init(vmcp_init); 221 module_exit(vmcp_exit); 222