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 #define KMSG_COMPONENT "vmcp" 15 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt 16 17 #include <linux/fs.h> 18 #include <linux/init.h> 19 #include <linux/kernel.h> 20 #include <linux/miscdevice.h> 21 #include <linux/module.h> 22 #include <asm/compat.h> 23 #include <asm/cpcmd.h> 24 #include <asm/debug.h> 25 #include <asm/uaccess.h> 26 #include "vmcp.h" 27 28 MODULE_LICENSE("GPL"); 29 MODULE_AUTHOR("Christian Borntraeger <borntraeger@de.ibm.com>"); 30 MODULE_DESCRIPTION("z/VM CP interface"); 31 32 static debug_info_t *vmcp_debug; 33 34 static int vmcp_open(struct inode *inode, struct file *file) 35 { 36 struct vmcp_session *session; 37 38 if (!capable(CAP_SYS_ADMIN)) 39 return -EPERM; 40 41 session = kmalloc(sizeof(*session), GFP_KERNEL); 42 if (!session) 43 return -ENOMEM; 44 45 session->bufsize = PAGE_SIZE; 46 session->response = NULL; 47 session->resp_size = 0; 48 mutex_init(&session->mutex); 49 file->private_data = session; 50 return nonseekable_open(inode, file); 51 } 52 53 static int vmcp_release(struct inode *inode, struct file *file) 54 { 55 struct vmcp_session *session; 56 57 session = (struct vmcp_session *)file->private_data; 58 file->private_data = NULL; 59 free_pages((unsigned long)session->response, get_order(session->bufsize)); 60 kfree(session); 61 return 0; 62 } 63 64 static ssize_t 65 vmcp_read(struct file *file, char __user *buff, size_t count, loff_t *ppos) 66 { 67 ssize_t ret; 68 size_t size; 69 struct vmcp_session *session; 70 71 session = file->private_data; 72 if (mutex_lock_interruptible(&session->mutex)) 73 return -ERESTARTSYS; 74 if (!session->response) { 75 mutex_unlock(&session->mutex); 76 return 0; 77 } 78 size = min_t(size_t, session->resp_size, session->bufsize); 79 ret = simple_read_from_buffer(buff, count, ppos, 80 session->response, size); 81 82 mutex_unlock(&session->mutex); 83 84 return ret; 85 } 86 87 static ssize_t 88 vmcp_write(struct file *file, const char __user *buff, size_t count, 89 loff_t *ppos) 90 { 91 char *cmd; 92 struct vmcp_session *session; 93 94 if (count > 240) 95 return -EINVAL; 96 cmd = kmalloc(count + 1, GFP_KERNEL); 97 if (!cmd) 98 return -ENOMEM; 99 if (copy_from_user(cmd, buff, count)) { 100 kfree(cmd); 101 return -EFAULT; 102 } 103 cmd[count] = '\0'; 104 session = (struct vmcp_session *)file->private_data; 105 if (mutex_lock_interruptible(&session->mutex)) { 106 kfree(cmd); 107 return -ERESTARTSYS; 108 } 109 if (!session->response) 110 session->response = (char *)__get_free_pages(GFP_KERNEL 111 | __GFP_REPEAT | GFP_DMA, 112 get_order(session->bufsize)); 113 if (!session->response) { 114 mutex_unlock(&session->mutex); 115 kfree(cmd); 116 return -ENOMEM; 117 } 118 debug_text_event(vmcp_debug, 1, cmd); 119 session->resp_size = cpcmd(cmd, session->response, session->bufsize, 120 &session->resp_code); 121 mutex_unlock(&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 __user *argp; 144 int temp; 145 146 session = (struct vmcp_session *)file->private_data; 147 if (is_compat_task()) 148 argp = compat_ptr(arg); 149 else 150 argp = (int __user *)arg; 151 if (mutex_lock_interruptible(&session->mutex)) 152 return -ERESTARTSYS; 153 switch (cmd) { 154 case VMCP_GETCODE: 155 temp = session->resp_code; 156 mutex_unlock(&session->mutex); 157 return put_user(temp, argp); 158 case VMCP_SETBUF: 159 free_pages((unsigned long)session->response, 160 get_order(session->bufsize)); 161 session->response=NULL; 162 temp = get_user(session->bufsize, argp); 163 if (get_order(session->bufsize) > 8) { 164 session->bufsize = PAGE_SIZE; 165 temp = -EINVAL; 166 } 167 mutex_unlock(&session->mutex); 168 return temp; 169 case VMCP_GETSIZE: 170 temp = session->resp_size; 171 mutex_unlock(&session->mutex); 172 return put_user(temp, argp); 173 default: 174 mutex_unlock(&session->mutex); 175 return -ENOIOCTLCMD; 176 } 177 } 178 179 static const struct file_operations vmcp_fops = { 180 .owner = THIS_MODULE, 181 .open = vmcp_open, 182 .release = vmcp_release, 183 .read = vmcp_read, 184 .write = vmcp_write, 185 .unlocked_ioctl = vmcp_ioctl, 186 .compat_ioctl = vmcp_ioctl, 187 }; 188 189 static struct miscdevice vmcp_dev = { 190 .name = "vmcp", 191 .minor = MISC_DYNAMIC_MINOR, 192 .fops = &vmcp_fops, 193 }; 194 195 static int __init vmcp_init(void) 196 { 197 int ret; 198 199 if (!MACHINE_IS_VM) { 200 pr_warning("The z/VM CP interface device driver cannot be " 201 "loaded without z/VM\n"); 202 return -ENODEV; 203 } 204 205 vmcp_debug = debug_register("vmcp", 1, 1, 240); 206 if (!vmcp_debug) 207 return -ENOMEM; 208 209 ret = debug_register_view(vmcp_debug, &debug_hex_ascii_view); 210 if (ret) { 211 debug_unregister(vmcp_debug); 212 return ret; 213 } 214 215 ret = misc_register(&vmcp_dev); 216 if (ret) { 217 debug_unregister(vmcp_debug); 218 return ret; 219 } 220 221 return 0; 222 } 223 224 static void __exit vmcp_exit(void) 225 { 226 misc_deregister(&vmcp_dev); 227 debug_unregister(vmcp_debug); 228 } 229 230 module_init(vmcp_init); 231 module_exit(vmcp_exit); 232