1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Character device driver for reading z/VM *MONITOR service records. 4 * 5 * Copyright IBM Corp. 2004, 2009 6 * 7 * Author: Gerald Schaefer <gerald.schaefer@de.ibm.com> 8 */ 9 10 #define KMSG_COMPONENT "monreader" 11 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt 12 13 #include <linux/module.h> 14 #include <linux/moduleparam.h> 15 #include <linux/init.h> 16 #include <linux/errno.h> 17 #include <linux/types.h> 18 #include <linux/kernel.h> 19 #include <linux/miscdevice.h> 20 #include <linux/ctype.h> 21 #include <linux/spinlock.h> 22 #include <linux/interrupt.h> 23 #include <linux/poll.h> 24 #include <linux/slab.h> 25 #include <net/iucv/iucv.h> 26 #include <linux/uaccess.h> 27 #include <asm/ebcdic.h> 28 #include <asm/extmem.h> 29 30 31 #define MON_COLLECT_SAMPLE 0x80 32 #define MON_COLLECT_EVENT 0x40 33 #define MON_SERVICE "*MONITOR" 34 #define MON_IN_USE 0x01 35 #define MON_MSGLIM 255 36 37 static char mon_dcss_name[9] = "MONDCSS\0"; 38 39 struct mon_msg { 40 u32 pos; 41 u32 mca_offset; 42 struct iucv_message msg; 43 char msglim_reached; 44 char replied_msglim; 45 }; 46 47 struct mon_private { 48 struct iucv_path *path; 49 struct mon_msg *msg_array[MON_MSGLIM]; 50 unsigned int write_index; 51 unsigned int read_index; 52 atomic_t msglim_count; 53 atomic_t read_ready; 54 atomic_t iucv_connected; 55 atomic_t iucv_severed; 56 }; 57 58 static unsigned long mon_in_use = 0; 59 60 static unsigned long mon_dcss_start; 61 static unsigned long mon_dcss_end; 62 63 static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue); 64 static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue); 65 66 static u8 user_data_connect[16] = { 67 /* Version code, must be 0x01 for shared mode */ 68 0x01, 69 /* what to collect */ 70 MON_COLLECT_SAMPLE | MON_COLLECT_EVENT, 71 /* DCSS name in EBCDIC, 8 bytes padded with blanks */ 72 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 73 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 74 }; 75 76 static u8 user_data_sever[16] = { 77 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 78 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 79 }; 80 81 /****************************************************************************** 82 * helper functions * 83 *****************************************************************************/ 84 /* 85 * Create the 8 bytes EBCDIC DCSS segment name from 86 * an ASCII name, incl. padding 87 */ 88 static void dcss_mkname(char *ascii_name, char *ebcdic_name) 89 { 90 int i; 91 92 for (i = 0; i < 8; i++) { 93 if (ascii_name[i] == '\0') 94 break; 95 ebcdic_name[i] = toupper(ascii_name[i]); 96 } 97 for (; i < 8; i++) 98 ebcdic_name[i] = ' '; 99 ASCEBC(ebcdic_name, 8); 100 } 101 102 static inline unsigned long mon_mca_start(struct mon_msg *monmsg) 103 { 104 return *(u32 *) &monmsg->msg.rmmsg; 105 } 106 107 static inline unsigned long mon_mca_end(struct mon_msg *monmsg) 108 { 109 return *(u32 *) &monmsg->msg.rmmsg[4]; 110 } 111 112 static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index) 113 { 114 return *((u8 *) mon_mca_start(monmsg) + monmsg->mca_offset + index); 115 } 116 117 static inline u32 mon_mca_size(struct mon_msg *monmsg) 118 { 119 return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1; 120 } 121 122 static inline u32 mon_rec_start(struct mon_msg *monmsg) 123 { 124 return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4)); 125 } 126 127 static inline u32 mon_rec_end(struct mon_msg *monmsg) 128 { 129 return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8)); 130 } 131 132 static int mon_check_mca(struct mon_msg *monmsg) 133 { 134 if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) || 135 (mon_rec_start(monmsg) < mon_dcss_start) || 136 (mon_rec_end(monmsg) > mon_dcss_end) || 137 (mon_mca_type(monmsg, 0) == 0) || 138 (mon_mca_size(monmsg) % 12 != 0) || 139 (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) || 140 (mon_mca_end(monmsg) > mon_dcss_end) || 141 (mon_mca_start(monmsg) < mon_dcss_start) || 142 ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0))) 143 return -EINVAL; 144 return 0; 145 } 146 147 static int mon_send_reply(struct mon_msg *monmsg, 148 struct mon_private *monpriv) 149 { 150 int rc; 151 152 rc = iucv_message_reply(monpriv->path, &monmsg->msg, 153 IUCV_IPRMDATA, NULL, 0); 154 atomic_dec(&monpriv->msglim_count); 155 if (likely(!monmsg->msglim_reached)) { 156 monmsg->pos = 0; 157 monmsg->mca_offset = 0; 158 monpriv->read_index = (monpriv->read_index + 1) % 159 MON_MSGLIM; 160 atomic_dec(&monpriv->read_ready); 161 } else 162 monmsg->replied_msglim = 1; 163 if (rc) { 164 pr_err("Reading monitor data failed with rc=%i\n", rc); 165 return -EIO; 166 } 167 return 0; 168 } 169 170 static void mon_free_mem(struct mon_private *monpriv) 171 { 172 int i; 173 174 for (i = 0; i < MON_MSGLIM; i++) 175 kfree(monpriv->msg_array[i]); 176 kfree(monpriv); 177 } 178 179 static struct mon_private *mon_alloc_mem(void) 180 { 181 int i; 182 struct mon_private *monpriv; 183 184 monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL); 185 if (!monpriv) 186 return NULL; 187 for (i = 0; i < MON_MSGLIM; i++) { 188 monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg), 189 GFP_KERNEL); 190 if (!monpriv->msg_array[i]) { 191 mon_free_mem(monpriv); 192 return NULL; 193 } 194 } 195 return monpriv; 196 } 197 198 static inline void mon_next_mca(struct mon_msg *monmsg) 199 { 200 if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12)) 201 return; 202 monmsg->mca_offset += 12; 203 monmsg->pos = 0; 204 } 205 206 static struct mon_msg *mon_next_message(struct mon_private *monpriv) 207 { 208 struct mon_msg *monmsg; 209 210 if (!atomic_read(&monpriv->read_ready)) 211 return NULL; 212 monmsg = monpriv->msg_array[monpriv->read_index]; 213 if (unlikely(monmsg->replied_msglim)) { 214 monmsg->replied_msglim = 0; 215 monmsg->msglim_reached = 0; 216 monmsg->pos = 0; 217 monmsg->mca_offset = 0; 218 monpriv->read_index = (monpriv->read_index + 1) % 219 MON_MSGLIM; 220 atomic_dec(&monpriv->read_ready); 221 return ERR_PTR(-EOVERFLOW); 222 } 223 return monmsg; 224 } 225 226 227 /****************************************************************************** 228 * IUCV handler * 229 *****************************************************************************/ 230 static void mon_iucv_path_complete(struct iucv_path *path, u8 *ipuser) 231 { 232 struct mon_private *monpriv = path->private; 233 234 atomic_set(&monpriv->iucv_connected, 1); 235 wake_up(&mon_conn_wait_queue); 236 } 237 238 static void mon_iucv_path_severed(struct iucv_path *path, u8 *ipuser) 239 { 240 struct mon_private *monpriv = path->private; 241 242 pr_err("z/VM *MONITOR system service disconnected with rc=%i\n", 243 ipuser[0]); 244 iucv_path_sever(path, NULL); 245 atomic_set(&monpriv->iucv_severed, 1); 246 wake_up(&mon_conn_wait_queue); 247 wake_up_interruptible(&mon_read_wait_queue); 248 } 249 250 static void mon_iucv_message_pending(struct iucv_path *path, 251 struct iucv_message *msg) 252 { 253 struct mon_private *monpriv = path->private; 254 255 memcpy(&monpriv->msg_array[monpriv->write_index]->msg, 256 msg, sizeof(*msg)); 257 if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) { 258 pr_warn("The read queue for monitor data is full\n"); 259 monpriv->msg_array[monpriv->write_index]->msglim_reached = 1; 260 } 261 monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM; 262 atomic_inc(&monpriv->read_ready); 263 wake_up_interruptible(&mon_read_wait_queue); 264 } 265 266 static struct iucv_handler monreader_iucv_handler = { 267 .path_complete = mon_iucv_path_complete, 268 .path_severed = mon_iucv_path_severed, 269 .message_pending = mon_iucv_message_pending, 270 }; 271 272 /****************************************************************************** 273 * file operations * 274 *****************************************************************************/ 275 static int mon_open(struct inode *inode, struct file *filp) 276 { 277 struct mon_private *monpriv; 278 int rc; 279 280 /* 281 * only one user allowed 282 */ 283 rc = -EBUSY; 284 if (test_and_set_bit(MON_IN_USE, &mon_in_use)) 285 goto out; 286 287 rc = -ENOMEM; 288 monpriv = mon_alloc_mem(); 289 if (!monpriv) 290 goto out_use; 291 292 /* 293 * Connect to *MONITOR service 294 */ 295 monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL); 296 if (!monpriv->path) 297 goto out_priv; 298 rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler, 299 MON_SERVICE, NULL, user_data_connect, monpriv); 300 if (rc) { 301 pr_err("Connecting to the z/VM *MONITOR system service " 302 "failed with rc=%i\n", rc); 303 rc = -EIO; 304 goto out_path; 305 } 306 /* 307 * Wait for connection confirmation 308 */ 309 wait_event(mon_conn_wait_queue, 310 atomic_read(&monpriv->iucv_connected) || 311 atomic_read(&monpriv->iucv_severed)); 312 if (atomic_read(&monpriv->iucv_severed)) { 313 atomic_set(&monpriv->iucv_severed, 0); 314 atomic_set(&monpriv->iucv_connected, 0); 315 rc = -EIO; 316 goto out_path; 317 } 318 filp->private_data = monpriv; 319 return nonseekable_open(inode, filp); 320 321 out_path: 322 iucv_path_free(monpriv->path); 323 out_priv: 324 mon_free_mem(monpriv); 325 out_use: 326 clear_bit(MON_IN_USE, &mon_in_use); 327 out: 328 return rc; 329 } 330 331 static int mon_close(struct inode *inode, struct file *filp) 332 { 333 int rc, i; 334 struct mon_private *monpriv = filp->private_data; 335 336 /* 337 * Close IUCV connection and unregister 338 */ 339 if (monpriv->path) { 340 rc = iucv_path_sever(monpriv->path, user_data_sever); 341 if (rc) 342 pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n", 343 rc); 344 iucv_path_free(monpriv->path); 345 } 346 347 atomic_set(&monpriv->iucv_severed, 0); 348 atomic_set(&monpriv->iucv_connected, 0); 349 atomic_set(&monpriv->read_ready, 0); 350 atomic_set(&monpriv->msglim_count, 0); 351 monpriv->write_index = 0; 352 monpriv->read_index = 0; 353 354 for (i = 0; i < MON_MSGLIM; i++) 355 kfree(monpriv->msg_array[i]); 356 kfree(monpriv); 357 clear_bit(MON_IN_USE, &mon_in_use); 358 return 0; 359 } 360 361 static ssize_t mon_read(struct file *filp, char __user *data, 362 size_t count, loff_t *ppos) 363 { 364 struct mon_private *monpriv = filp->private_data; 365 struct mon_msg *monmsg; 366 int ret; 367 u32 mce_start; 368 369 monmsg = mon_next_message(monpriv); 370 if (IS_ERR(monmsg)) 371 return PTR_ERR(monmsg); 372 373 if (!monmsg) { 374 if (filp->f_flags & O_NONBLOCK) 375 return -EAGAIN; 376 ret = wait_event_interruptible(mon_read_wait_queue, 377 atomic_read(&monpriv->read_ready) || 378 atomic_read(&monpriv->iucv_severed)); 379 if (ret) 380 return ret; 381 if (unlikely(atomic_read(&monpriv->iucv_severed))) 382 return -EIO; 383 monmsg = monpriv->msg_array[monpriv->read_index]; 384 } 385 386 if (!monmsg->pos) 387 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset; 388 if (mon_check_mca(monmsg)) 389 goto reply; 390 391 /* read monitor control element (12 bytes) first */ 392 mce_start = mon_mca_start(monmsg) + monmsg->mca_offset; 393 if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) { 394 count = min(count, (size_t) mce_start + 12 - monmsg->pos); 395 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos, 396 count); 397 if (ret) 398 return -EFAULT; 399 monmsg->pos += count; 400 if (monmsg->pos == mce_start + 12) 401 monmsg->pos = mon_rec_start(monmsg); 402 goto out_copy; 403 } 404 405 /* read records */ 406 if (monmsg->pos <= mon_rec_end(monmsg)) { 407 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos 408 + 1); 409 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos, 410 count); 411 if (ret) 412 return -EFAULT; 413 monmsg->pos += count; 414 if (monmsg->pos > mon_rec_end(monmsg)) 415 mon_next_mca(monmsg); 416 goto out_copy; 417 } 418 reply: 419 ret = mon_send_reply(monmsg, monpriv); 420 return ret; 421 422 out_copy: 423 *ppos += count; 424 return count; 425 } 426 427 static __poll_t mon_poll(struct file *filp, struct poll_table_struct *p) 428 { 429 struct mon_private *monpriv = filp->private_data; 430 431 poll_wait(filp, &mon_read_wait_queue, p); 432 if (unlikely(atomic_read(&monpriv->iucv_severed))) 433 return EPOLLERR; 434 if (atomic_read(&monpriv->read_ready)) 435 return EPOLLIN | EPOLLRDNORM; 436 return 0; 437 } 438 439 static const struct file_operations mon_fops = { 440 .owner = THIS_MODULE, 441 .open = &mon_open, 442 .release = &mon_close, 443 .read = &mon_read, 444 .poll = &mon_poll, 445 .llseek = noop_llseek, 446 }; 447 448 static struct miscdevice mon_dev = { 449 .name = "monreader", 450 .fops = &mon_fops, 451 .minor = MISC_DYNAMIC_MINOR, 452 }; 453 454 /****************************************************************************** 455 * module init/exit * 456 *****************************************************************************/ 457 static int __init mon_init(void) 458 { 459 int rc; 460 461 if (!MACHINE_IS_VM) { 462 pr_err("The z/VM *MONITOR record device driver cannot be " 463 "loaded without z/VM\n"); 464 return -ENODEV; 465 } 466 467 /* 468 * Register with IUCV and connect to *MONITOR service 469 */ 470 rc = iucv_register(&monreader_iucv_handler, 1); 471 if (rc) { 472 pr_err("The z/VM *MONITOR record device driver failed to " 473 "register with IUCV\n"); 474 return rc; 475 } 476 477 rc = segment_type(mon_dcss_name); 478 if (rc < 0) { 479 segment_warning(rc, mon_dcss_name); 480 goto out_iucv; 481 } 482 if (rc != SEG_TYPE_SC) { 483 pr_err("The specified *MONITOR DCSS %s does not have the " 484 "required type SC\n", mon_dcss_name); 485 rc = -EINVAL; 486 goto out_iucv; 487 } 488 489 rc = segment_load(mon_dcss_name, SEGMENT_SHARED, 490 &mon_dcss_start, &mon_dcss_end); 491 if (rc < 0) { 492 segment_warning(rc, mon_dcss_name); 493 rc = -EINVAL; 494 goto out_iucv; 495 } 496 dcss_mkname(mon_dcss_name, &user_data_connect[8]); 497 498 /* 499 * misc_register() has to be the last action in module_init(), because 500 * file operations will be available right after this. 501 */ 502 rc = misc_register(&mon_dev); 503 if (rc < 0 ) 504 goto out; 505 return 0; 506 507 out: 508 segment_unload(mon_dcss_name); 509 out_iucv: 510 iucv_unregister(&monreader_iucv_handler, 1); 511 return rc; 512 } 513 514 static void __exit mon_exit(void) 515 { 516 segment_unload(mon_dcss_name); 517 misc_deregister(&mon_dev); 518 iucv_unregister(&monreader_iucv_handler, 1); 519 return; 520 } 521 522 523 module_init(mon_init); 524 module_exit(mon_exit); 525 526 module_param_string(mondcss, mon_dcss_name, 9, 0444); 527 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR " 528 "service, max. 8 chars. Default is MONDCSS"); 529 530 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>"); 531 MODULE_DESCRIPTION("Character device driver for reading z/VM " 532 "monitor service records."); 533 MODULE_LICENSE("GPL"); 534