1 /* 2 * Copyright IBM Corp. 2004, 2010 3 * Interface implementation for communication with the z/VM control program 4 * 5 * Author(s): Christian Borntraeger <borntraeger@de.ibm.com> 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/compat.h> 17 #include <linux/kernel.h> 18 #include <linux/miscdevice.h> 19 #include <linux/slab.h> 20 #include <linux/uaccess.h> 21 #include <linux/export.h> 22 #include <linux/mutex.h> 23 #include <linux/cma.h> 24 #include <linux/mm.h> 25 #include <asm/compat.h> 26 #include <asm/cpcmd.h> 27 #include <asm/debug.h> 28 #include <asm/vmcp.h> 29 30 struct vmcp_session { 31 char *response; 32 unsigned int bufsize; 33 unsigned int cma_alloc : 1; 34 int resp_size; 35 int resp_code; 36 struct mutex mutex; 37 }; 38 39 static debug_info_t *vmcp_debug; 40 41 static unsigned long vmcp_cma_size __initdata = CONFIG_VMCP_CMA_SIZE * 1024 * 1024; 42 static struct cma *vmcp_cma; 43 44 static int __init early_parse_vmcp_cma(char *p) 45 { 46 vmcp_cma_size = ALIGN(memparse(p, NULL), PAGE_SIZE); 47 return 0; 48 } 49 early_param("vmcp_cma", early_parse_vmcp_cma); 50 51 void __init vmcp_cma_reserve(void) 52 { 53 if (!MACHINE_IS_VM) 54 return; 55 cma_declare_contiguous(0, vmcp_cma_size, 0, 0, 0, false, "vmcp", &vmcp_cma); 56 } 57 58 static void vmcp_response_alloc(struct vmcp_session *session) 59 { 60 struct page *page = NULL; 61 int nr_pages, order; 62 63 order = get_order(session->bufsize); 64 nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT; 65 /* 66 * For anything below order 3 allocations rely on the buddy 67 * allocator. If such low-order allocations can't be handled 68 * anymore the system won't work anyway. 69 */ 70 if (order > 2) 71 page = cma_alloc(vmcp_cma, nr_pages, 0, GFP_KERNEL); 72 if (page) { 73 session->response = (char *)page_to_phys(page); 74 session->cma_alloc = 1; 75 return; 76 } 77 session->response = (char *)__get_free_pages(GFP_KERNEL | __GFP_RETRY_MAYFAIL, order); 78 } 79 80 static void vmcp_response_free(struct vmcp_session *session) 81 { 82 int nr_pages, order; 83 struct page *page; 84 85 if (!session->response) 86 return; 87 order = get_order(session->bufsize); 88 nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT; 89 if (session->cma_alloc) { 90 page = phys_to_page((unsigned long)session->response); 91 cma_release(vmcp_cma, page, nr_pages); 92 session->cma_alloc = 0; 93 goto out; 94 } 95 free_pages((unsigned long)session->response, order); 96 out: 97 session->response = NULL; 98 } 99 100 static int vmcp_open(struct inode *inode, struct file *file) 101 { 102 struct vmcp_session *session; 103 104 if (!capable(CAP_SYS_ADMIN)) 105 return -EPERM; 106 107 session = kmalloc(sizeof(*session), GFP_KERNEL); 108 if (!session) 109 return -ENOMEM; 110 111 session->bufsize = PAGE_SIZE; 112 session->response = NULL; 113 session->resp_size = 0; 114 mutex_init(&session->mutex); 115 file->private_data = session; 116 return nonseekable_open(inode, file); 117 } 118 119 static int vmcp_release(struct inode *inode, struct file *file) 120 { 121 struct vmcp_session *session; 122 123 session = file->private_data; 124 file->private_data = NULL; 125 vmcp_response_free(session); 126 kfree(session); 127 return 0; 128 } 129 130 static ssize_t 131 vmcp_read(struct file *file, char __user *buff, size_t count, loff_t *ppos) 132 { 133 ssize_t ret; 134 size_t size; 135 struct vmcp_session *session; 136 137 session = file->private_data; 138 if (mutex_lock_interruptible(&session->mutex)) 139 return -ERESTARTSYS; 140 if (!session->response) { 141 mutex_unlock(&session->mutex); 142 return 0; 143 } 144 size = min_t(size_t, session->resp_size, session->bufsize); 145 ret = simple_read_from_buffer(buff, count, ppos, 146 session->response, size); 147 148 mutex_unlock(&session->mutex); 149 150 return ret; 151 } 152 153 static ssize_t 154 vmcp_write(struct file *file, const char __user *buff, size_t count, 155 loff_t *ppos) 156 { 157 char *cmd; 158 struct vmcp_session *session; 159 160 if (count > 240) 161 return -EINVAL; 162 cmd = memdup_user_nul(buff, count); 163 if (IS_ERR(cmd)) 164 return PTR_ERR(cmd); 165 session = file->private_data; 166 if (mutex_lock_interruptible(&session->mutex)) { 167 kfree(cmd); 168 return -ERESTARTSYS; 169 } 170 if (!session->response) 171 vmcp_response_alloc(session); 172 if (!session->response) { 173 mutex_unlock(&session->mutex); 174 kfree(cmd); 175 return -ENOMEM; 176 } 177 debug_text_event(vmcp_debug, 1, cmd); 178 session->resp_size = cpcmd(cmd, session->response, session->bufsize, 179 &session->resp_code); 180 mutex_unlock(&session->mutex); 181 kfree(cmd); 182 *ppos = 0; /* reset the file pointer after a command */ 183 return count; 184 } 185 186 187 /* 188 * These ioctls are available, as the semantics of the diagnose 8 call 189 * does not fit very well into a Linux call. Diagnose X'08' is described in 190 * CP Programming Services SC24-6084-00 191 * 192 * VMCP_GETCODE: gives the CP return code back to user space 193 * VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8 194 * expects adjacent pages in real storage and to make matters worse, we 195 * dont know the size of the response. Therefore we default to PAGESIZE and 196 * let userspace to change the response size, if userspace expects a bigger 197 * response 198 */ 199 static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 200 { 201 struct vmcp_session *session; 202 int ret = -ENOTTY; 203 int __user *argp; 204 205 session = file->private_data; 206 if (is_compat_task()) 207 argp = compat_ptr(arg); 208 else 209 argp = (int __user *)arg; 210 if (mutex_lock_interruptible(&session->mutex)) 211 return -ERESTARTSYS; 212 switch (cmd) { 213 case VMCP_GETCODE: 214 ret = put_user(session->resp_code, argp); 215 break; 216 case VMCP_SETBUF: 217 vmcp_response_free(session); 218 ret = get_user(session->bufsize, argp); 219 if (ret) 220 session->bufsize = PAGE_SIZE; 221 if (!session->bufsize || get_order(session->bufsize) > 8) { 222 session->bufsize = PAGE_SIZE; 223 ret = -EINVAL; 224 } 225 break; 226 case VMCP_GETSIZE: 227 ret = put_user(session->resp_size, argp); 228 break; 229 default: 230 break; 231 } 232 mutex_unlock(&session->mutex); 233 return ret; 234 } 235 236 static const struct file_operations vmcp_fops = { 237 .owner = THIS_MODULE, 238 .open = vmcp_open, 239 .release = vmcp_release, 240 .read = vmcp_read, 241 .write = vmcp_write, 242 .unlocked_ioctl = vmcp_ioctl, 243 .compat_ioctl = vmcp_ioctl, 244 .llseek = no_llseek, 245 }; 246 247 static struct miscdevice vmcp_dev = { 248 .name = "vmcp", 249 .minor = MISC_DYNAMIC_MINOR, 250 .fops = &vmcp_fops, 251 }; 252 253 static int __init vmcp_init(void) 254 { 255 int ret; 256 257 if (!MACHINE_IS_VM) 258 return 0; 259 260 vmcp_debug = debug_register("vmcp", 1, 1, 240); 261 if (!vmcp_debug) 262 return -ENOMEM; 263 264 ret = debug_register_view(vmcp_debug, &debug_hex_ascii_view); 265 if (ret) { 266 debug_unregister(vmcp_debug); 267 return ret; 268 } 269 270 ret = misc_register(&vmcp_dev); 271 if (ret) 272 debug_unregister(vmcp_debug); 273 return ret; 274 } 275 device_initcall(vmcp_init); 276