1 /* 2 * Copyright IBM Corp. 2004,2007 3 * Interface implementation for communication with the z/VM control program 4 * Author(s): Christian Borntraeger <borntraeger@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 <borntraeger@de.ibm.com>"); 26 MODULE_DESCRIPTION("z/VM CP interface"); 27 28 #define PRINTK_HEADER "vmcp: " 29 30 static debug_info_t *vmcp_debug; 31 32 static int vmcp_open(struct inode *inode, struct file *file) 33 { 34 struct vmcp_session *session; 35 36 if (!capable(CAP_SYS_ADMIN)) 37 return -EPERM; 38 39 session = kmalloc(sizeof(*session), GFP_KERNEL); 40 if (!session) 41 return -ENOMEM; 42 session->bufsize = PAGE_SIZE; 43 session->response = NULL; 44 session->resp_size = 0; 45 mutex_init(&session->mutex); 46 file->private_data = session; 47 return nonseekable_open(inode, file); 48 } 49 50 static int vmcp_release(struct inode *inode, struct file *file) 51 { 52 struct vmcp_session *session; 53 54 session = (struct vmcp_session *)file->private_data; 55 file->private_data = NULL; 56 free_pages((unsigned long)session->response, get_order(session->bufsize)); 57 kfree(session); 58 return 0; 59 } 60 61 static ssize_t 62 vmcp_read(struct file *file, char __user *buff, size_t count, loff_t *ppos) 63 { 64 size_t tocopy; 65 struct vmcp_session *session; 66 67 session = (struct vmcp_session *)file->private_data; 68 if (mutex_lock_interruptible(&session->mutex)) 69 return -ERESTARTSYS; 70 if (!session->response) { 71 mutex_unlock(&session->mutex); 72 return 0; 73 } 74 if (*ppos > session->resp_size) { 75 mutex_unlock(&session->mutex); 76 return 0; 77 } 78 tocopy = min(session->resp_size - (size_t) (*ppos), count); 79 tocopy = min(tocopy, session->bufsize - (size_t) (*ppos)); 80 81 if (copy_to_user(buff, session->response + (*ppos), tocopy)) { 82 mutex_unlock(&session->mutex); 83 return -EFAULT; 84 } 85 mutex_unlock(&session->mutex); 86 *ppos += tocopy; 87 return tocopy; 88 } 89 90 static ssize_t 91 vmcp_write(struct file *file, const char __user *buff, size_t count, 92 loff_t *ppos) 93 { 94 char *cmd; 95 struct vmcp_session *session; 96 97 if (count > 240) 98 return -EINVAL; 99 cmd = kmalloc(count + 1, GFP_KERNEL); 100 if (!cmd) 101 return -ENOMEM; 102 if (copy_from_user(cmd, buff, count)) { 103 kfree(cmd); 104 return -EFAULT; 105 } 106 cmd[count] = '\0'; 107 session = (struct vmcp_session *)file->private_data; 108 if (mutex_lock_interruptible(&session->mutex)) { 109 kfree(cmd); 110 return -ERESTARTSYS; 111 } 112 if (!session->response) 113 session->response = (char *)__get_free_pages(GFP_KERNEL 114 | __GFP_REPEAT | GFP_DMA, 115 get_order(session->bufsize)); 116 if (!session->response) { 117 mutex_unlock(&session->mutex); 118 kfree(cmd); 119 return -ENOMEM; 120 } 121 debug_text_event(vmcp_debug, 1, cmd); 122 session->resp_size = cpcmd(cmd, session->response, session->bufsize, 123 &session->resp_code); 124 mutex_unlock(&session->mutex); 125 kfree(cmd); 126 *ppos = 0; /* reset the file pointer after a command */ 127 return count; 128 } 129 130 131 /* 132 * These ioctls are available, as the semantics of the diagnose 8 call 133 * does not fit very well into a Linux call. Diagnose X'08' is described in 134 * CP Programming Services SC24-6084-00 135 * 136 * VMCP_GETCODE: gives the CP return code back to user space 137 * VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8 138 * expects adjacent pages in real storage and to make matters worse, we 139 * dont know the size of the response. Therefore we default to PAGESIZE and 140 * let userspace to change the response size, if userspace expects a bigger 141 * response 142 */ 143 static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 144 { 145 struct vmcp_session *session; 146 int temp; 147 148 session = (struct vmcp_session *)file->private_data; 149 if (mutex_lock_interruptible(&session->mutex)) 150 return -ERESTARTSYS; 151 switch (cmd) { 152 case VMCP_GETCODE: 153 temp = session->resp_code; 154 mutex_unlock(&session->mutex); 155 return put_user(temp, (int __user *)arg); 156 case VMCP_SETBUF: 157 free_pages((unsigned long)session->response, 158 get_order(session->bufsize)); 159 session->response=NULL; 160 temp = get_user(session->bufsize, (int __user *)arg); 161 if (get_order(session->bufsize) > 8) { 162 session->bufsize = PAGE_SIZE; 163 temp = -EINVAL; 164 } 165 mutex_unlock(&session->mutex); 166 return temp; 167 case VMCP_GETSIZE: 168 temp = session->resp_size; 169 mutex_unlock(&session->mutex); 170 return put_user(temp, (int __user *)arg); 171 default: 172 mutex_unlock(&session->mutex); 173 return -ENOIOCTLCMD; 174 } 175 } 176 177 static const struct file_operations vmcp_fops = { 178 .owner = THIS_MODULE, 179 .open = vmcp_open, 180 .release = vmcp_release, 181 .read = vmcp_read, 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 PRINT_WARN("z/VM CP interface is only available under z/VM\n"); 199 return -ENODEV; 200 } 201 vmcp_debug = debug_register("vmcp", 1, 1, 240); 202 if (!vmcp_debug) { 203 PRINT_ERR("z/VM CP interface not loaded. Could not register " 204 "debug feature\n"); 205 return -ENOMEM; 206 } 207 ret = debug_register_view(vmcp_debug, &debug_hex_ascii_view); 208 if (ret) { 209 PRINT_ERR("z/VM CP interface not loaded. Could not register " 210 "debug feature view. Error code: %d\n", ret); 211 debug_unregister(vmcp_debug); 212 return ret; 213 } 214 ret = misc_register(&vmcp_dev); 215 if (ret) { 216 PRINT_ERR("z/VM CP interface not loaded. Could not register " 217 "misc device. Error code: %d\n", ret); 218 debug_unregister(vmcp_debug); 219 return ret; 220 } 221 PRINT_INFO("z/VM CP interface loaded\n"); 222 return 0; 223 } 224 225 static void __exit vmcp_exit(void) 226 { 227 misc_deregister(&vmcp_dev); 228 debug_unregister(vmcp_debug); 229 PRINT_INFO("z/VM CP interface unloaded.\n"); 230 } 231 232 module_init(vmcp_init); 233 module_exit(vmcp_exit); 234