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); 220