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/device.h> 25 #include <linux/slab.h> 26 #include <net/iucv/iucv.h> 27 #include <linux/uaccess.h> 28 #include <asm/ebcdic.h> 29 #include <asm/extmem.h> 30 31 32 #define MON_COLLECT_SAMPLE 0x80 33 #define MON_COLLECT_EVENT 0x40 34 #define MON_SERVICE "*MONITOR" 35 #define MON_IN_USE 0x01 36 #define MON_MSGLIM 255 37 38 static char mon_dcss_name[9] = "MONDCSS\0"; 39 40 struct mon_msg { 41 u32 pos; 42 u32 mca_offset; 43 struct iucv_message msg; 44 char msglim_reached; 45 char replied_msglim; 46 }; 47 48 struct mon_private { 49 struct iucv_path *path; 50 struct mon_msg *msg_array[MON_MSGLIM]; 51 unsigned int write_index; 52 unsigned int read_index; 53 atomic_t msglim_count; 54 atomic_t read_ready; 55 atomic_t iucv_connected; 56 atomic_t iucv_severed; 57 }; 58 59 static unsigned long mon_in_use = 0; 60 61 static unsigned long mon_dcss_start; 62 static unsigned long mon_dcss_end; 63 64 static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue); 65 static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue); 66 67 static u8 user_data_connect[16] = { 68 /* Version code, must be 0x01 for shared mode */ 69 0x01, 70 /* what to collect */ 71 MON_COLLECT_SAMPLE | MON_COLLECT_EVENT, 72 /* DCSS name in EBCDIC, 8 bytes padded with blanks */ 73 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 74 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 75 }; 76 77 static u8 user_data_sever[16] = { 78 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 79 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 80 }; 81 82 static struct device *monreader_device; 83 84 /****************************************************************************** 85 * helper functions * 86 *****************************************************************************/ 87 /* 88 * Create the 8 bytes EBCDIC DCSS segment name from 89 * an ASCII name, incl. padding 90 */ 91 static void dcss_mkname(char *ascii_name, char *ebcdic_name) 92 { 93 int i; 94 95 for (i = 0; i < 8; i++) { 96 if (ascii_name[i] == '\0') 97 break; 98 ebcdic_name[i] = toupper(ascii_name[i]); 99 } 100 for (; i < 8; i++) 101 ebcdic_name[i] = ' '; 102 ASCEBC(ebcdic_name, 8); 103 } 104 105 static inline unsigned long mon_mca_start(struct mon_msg *monmsg) 106 { 107 return *(u32 *) &monmsg->msg.rmmsg; 108 } 109 110 static inline unsigned long mon_mca_end(struct mon_msg *monmsg) 111 { 112 return *(u32 *) &monmsg->msg.rmmsg[4]; 113 } 114 115 static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index) 116 { 117 return *((u8 *) mon_mca_start(monmsg) + monmsg->mca_offset + index); 118 } 119 120 static inline u32 mon_mca_size(struct mon_msg *monmsg) 121 { 122 return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1; 123 } 124 125 static inline u32 mon_rec_start(struct mon_msg *monmsg) 126 { 127 return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4)); 128 } 129 130 static inline u32 mon_rec_end(struct mon_msg *monmsg) 131 { 132 return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8)); 133 } 134 135 static int mon_check_mca(struct mon_msg *monmsg) 136 { 137 if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) || 138 (mon_rec_start(monmsg) < mon_dcss_start) || 139 (mon_rec_end(monmsg) > mon_dcss_end) || 140 (mon_mca_type(monmsg, 0) == 0) || 141 (mon_mca_size(monmsg) % 12 != 0) || 142 (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) || 143 (mon_mca_end(monmsg) > mon_dcss_end) || 144 (mon_mca_start(monmsg) < mon_dcss_start) || 145 ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0))) 146 return -EINVAL; 147 return 0; 148 } 149 150 static int mon_send_reply(struct mon_msg *monmsg, 151 struct mon_private *monpriv) 152 { 153 int rc; 154 155 rc = iucv_message_reply(monpriv->path, &monmsg->msg, 156 IUCV_IPRMDATA, NULL, 0); 157 atomic_dec(&monpriv->msglim_count); 158 if (likely(!monmsg->msglim_reached)) { 159 monmsg->pos = 0; 160 monmsg->mca_offset = 0; 161 monpriv->read_index = (monpriv->read_index + 1) % 162 MON_MSGLIM; 163 atomic_dec(&monpriv->read_ready); 164 } else 165 monmsg->replied_msglim = 1; 166 if (rc) { 167 pr_err("Reading monitor data failed with rc=%i\n", rc); 168 return -EIO; 169 } 170 return 0; 171 } 172 173 static void mon_free_mem(struct mon_private *monpriv) 174 { 175 int i; 176 177 for (i = 0; i < MON_MSGLIM; i++) 178 kfree(monpriv->msg_array[i]); 179 kfree(monpriv); 180 } 181 182 static struct mon_private *mon_alloc_mem(void) 183 { 184 int i; 185 struct mon_private *monpriv; 186 187 monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL); 188 if (!monpriv) 189 return NULL; 190 for (i = 0; i < MON_MSGLIM; i++) { 191 monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg), 192 GFP_KERNEL); 193 if (!monpriv->msg_array[i]) { 194 mon_free_mem(monpriv); 195 return NULL; 196 } 197 } 198 return monpriv; 199 } 200 201 static inline void mon_next_mca(struct mon_msg *monmsg) 202 { 203 if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12)) 204 return; 205 monmsg->mca_offset += 12; 206 monmsg->pos = 0; 207 } 208 209 static struct mon_msg *mon_next_message(struct mon_private *monpriv) 210 { 211 struct mon_msg *monmsg; 212 213 if (!atomic_read(&monpriv->read_ready)) 214 return NULL; 215 monmsg = monpriv->msg_array[monpriv->read_index]; 216 if (unlikely(monmsg->replied_msglim)) { 217 monmsg->replied_msglim = 0; 218 monmsg->msglim_reached = 0; 219 monmsg->pos = 0; 220 monmsg->mca_offset = 0; 221 monpriv->read_index = (monpriv->read_index + 1) % 222 MON_MSGLIM; 223 atomic_dec(&monpriv->read_ready); 224 return ERR_PTR(-EOVERFLOW); 225 } 226 return monmsg; 227 } 228 229 230 /****************************************************************************** 231 * IUCV handler * 232 *****************************************************************************/ 233 static void mon_iucv_path_complete(struct iucv_path *path, u8 *ipuser) 234 { 235 struct mon_private *monpriv = path->private; 236 237 atomic_set(&monpriv->iucv_connected, 1); 238 wake_up(&mon_conn_wait_queue); 239 } 240 241 static void mon_iucv_path_severed(struct iucv_path *path, u8 *ipuser) 242 { 243 struct mon_private *monpriv = path->private; 244 245 pr_err("z/VM *MONITOR system service disconnected with rc=%i\n", 246 ipuser[0]); 247 iucv_path_sever(path, NULL); 248 atomic_set(&monpriv->iucv_severed, 1); 249 wake_up(&mon_conn_wait_queue); 250 wake_up_interruptible(&mon_read_wait_queue); 251 } 252 253 static void mon_iucv_message_pending(struct iucv_path *path, 254 struct iucv_message *msg) 255 { 256 struct mon_private *monpriv = path->private; 257 258 memcpy(&monpriv->msg_array[monpriv->write_index]->msg, 259 msg, sizeof(*msg)); 260 if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) { 261 pr_warn("The read queue for monitor data is full\n"); 262 monpriv->msg_array[monpriv->write_index]->msglim_reached = 1; 263 } 264 monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM; 265 atomic_inc(&monpriv->read_ready); 266 wake_up_interruptible(&mon_read_wait_queue); 267 } 268 269 static struct iucv_handler monreader_iucv_handler = { 270 .path_complete = mon_iucv_path_complete, 271 .path_severed = mon_iucv_path_severed, 272 .message_pending = mon_iucv_message_pending, 273 }; 274 275 /****************************************************************************** 276 * file operations * 277 *****************************************************************************/ 278 static int mon_open(struct inode *inode, struct file *filp) 279 { 280 struct mon_private *monpriv; 281 int rc; 282 283 /* 284 * only one user allowed 285 */ 286 rc = -EBUSY; 287 if (test_and_set_bit(MON_IN_USE, &mon_in_use)) 288 goto out; 289 290 rc = -ENOMEM; 291 monpriv = mon_alloc_mem(); 292 if (!monpriv) 293 goto out_use; 294 295 /* 296 * Connect to *MONITOR service 297 */ 298 monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL); 299 if (!monpriv->path) 300 goto out_priv; 301 rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler, 302 MON_SERVICE, NULL, user_data_connect, monpriv); 303 if (rc) { 304 pr_err("Connecting to the z/VM *MONITOR system service " 305 "failed with rc=%i\n", rc); 306 rc = -EIO; 307 goto out_path; 308 } 309 /* 310 * Wait for connection confirmation 311 */ 312 wait_event(mon_conn_wait_queue, 313 atomic_read(&monpriv->iucv_connected) || 314 atomic_read(&monpriv->iucv_severed)); 315 if (atomic_read(&monpriv->iucv_severed)) { 316 atomic_set(&monpriv->iucv_severed, 0); 317 atomic_set(&monpriv->iucv_connected, 0); 318 rc = -EIO; 319 goto out_path; 320 } 321 filp->private_data = monpriv; 322 dev_set_drvdata(monreader_device, monpriv); 323 return nonseekable_open(inode, filp); 324 325 out_path: 326 iucv_path_free(monpriv->path); 327 out_priv: 328 mon_free_mem(monpriv); 329 out_use: 330 clear_bit(MON_IN_USE, &mon_in_use); 331 out: 332 return rc; 333 } 334 335 static int mon_close(struct inode *inode, struct file *filp) 336 { 337 int rc, i; 338 struct mon_private *monpriv = filp->private_data; 339 340 /* 341 * Close IUCV connection and unregister 342 */ 343 if (monpriv->path) { 344 rc = iucv_path_sever(monpriv->path, user_data_sever); 345 if (rc) 346 pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n", 347 rc); 348 iucv_path_free(monpriv->path); 349 } 350 351 atomic_set(&monpriv->iucv_severed, 0); 352 atomic_set(&monpriv->iucv_connected, 0); 353 atomic_set(&monpriv->read_ready, 0); 354 atomic_set(&monpriv->msglim_count, 0); 355 monpriv->write_index = 0; 356 monpriv->read_index = 0; 357 dev_set_drvdata(monreader_device, NULL); 358 359 for (i = 0; i < MON_MSGLIM; i++) 360 kfree(monpriv->msg_array[i]); 361 kfree(monpriv); 362 clear_bit(MON_IN_USE, &mon_in_use); 363 return 0; 364 } 365 366 static ssize_t mon_read(struct file *filp, char __user *data, 367 size_t count, loff_t *ppos) 368 { 369 struct mon_private *monpriv = filp->private_data; 370 struct mon_msg *monmsg; 371 int ret; 372 u32 mce_start; 373 374 monmsg = mon_next_message(monpriv); 375 if (IS_ERR(monmsg)) 376 return PTR_ERR(monmsg); 377 378 if (!monmsg) { 379 if (filp->f_flags & O_NONBLOCK) 380 return -EAGAIN; 381 ret = wait_event_interruptible(mon_read_wait_queue, 382 atomic_read(&monpriv->read_ready) || 383 atomic_read(&monpriv->iucv_severed)); 384 if (ret) 385 return ret; 386 if (unlikely(atomic_read(&monpriv->iucv_severed))) 387 return -EIO; 388 monmsg = monpriv->msg_array[monpriv->read_index]; 389 } 390 391 if (!monmsg->pos) 392 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset; 393 if (mon_check_mca(monmsg)) 394 goto reply; 395 396 /* read monitor control element (12 bytes) first */ 397 mce_start = mon_mca_start(monmsg) + monmsg->mca_offset; 398 if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) { 399 count = min(count, (size_t) mce_start + 12 - monmsg->pos); 400 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos, 401 count); 402 if (ret) 403 return -EFAULT; 404 monmsg->pos += count; 405 if (monmsg->pos == mce_start + 12) 406 monmsg->pos = mon_rec_start(monmsg); 407 goto out_copy; 408 } 409 410 /* read records */ 411 if (monmsg->pos <= mon_rec_end(monmsg)) { 412 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos 413 + 1); 414 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos, 415 count); 416 if (ret) 417 return -EFAULT; 418 monmsg->pos += count; 419 if (monmsg->pos > mon_rec_end(monmsg)) 420 mon_next_mca(monmsg); 421 goto out_copy; 422 } 423 reply: 424 ret = mon_send_reply(monmsg, monpriv); 425 return ret; 426 427 out_copy: 428 *ppos += count; 429 return count; 430 } 431 432 static __poll_t mon_poll(struct file *filp, struct poll_table_struct *p) 433 { 434 struct mon_private *monpriv = filp->private_data; 435 436 poll_wait(filp, &mon_read_wait_queue, p); 437 if (unlikely(atomic_read(&monpriv->iucv_severed))) 438 return EPOLLERR; 439 if (atomic_read(&monpriv->read_ready)) 440 return EPOLLIN | EPOLLRDNORM; 441 return 0; 442 } 443 444 static const struct file_operations mon_fops = { 445 .owner = THIS_MODULE, 446 .open = &mon_open, 447 .release = &mon_close, 448 .read = &mon_read, 449 .poll = &mon_poll, 450 .llseek = noop_llseek, 451 }; 452 453 static struct miscdevice mon_dev = { 454 .name = "monreader", 455 .fops = &mon_fops, 456 .minor = MISC_DYNAMIC_MINOR, 457 }; 458 459 460 /****************************************************************************** 461 * suspend / resume * 462 *****************************************************************************/ 463 static int monreader_freeze(struct device *dev) 464 { 465 struct mon_private *monpriv = dev_get_drvdata(dev); 466 int rc; 467 468 if (!monpriv) 469 return 0; 470 if (monpriv->path) { 471 rc = iucv_path_sever(monpriv->path, user_data_sever); 472 if (rc) 473 pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n", 474 rc); 475 iucv_path_free(monpriv->path); 476 } 477 atomic_set(&monpriv->iucv_severed, 0); 478 atomic_set(&monpriv->iucv_connected, 0); 479 atomic_set(&monpriv->read_ready, 0); 480 atomic_set(&monpriv->msglim_count, 0); 481 monpriv->write_index = 0; 482 monpriv->read_index = 0; 483 monpriv->path = NULL; 484 return 0; 485 } 486 487 static int monreader_thaw(struct device *dev) 488 { 489 struct mon_private *monpriv = dev_get_drvdata(dev); 490 int rc; 491 492 if (!monpriv) 493 return 0; 494 rc = -ENOMEM; 495 monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL); 496 if (!monpriv->path) 497 goto out; 498 rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler, 499 MON_SERVICE, NULL, user_data_connect, monpriv); 500 if (rc) { 501 pr_err("Connecting to the z/VM *MONITOR system service " 502 "failed with rc=%i\n", rc); 503 goto out_path; 504 } 505 wait_event(mon_conn_wait_queue, 506 atomic_read(&monpriv->iucv_connected) || 507 atomic_read(&monpriv->iucv_severed)); 508 if (atomic_read(&monpriv->iucv_severed)) 509 goto out_path; 510 return 0; 511 out_path: 512 rc = -EIO; 513 iucv_path_free(monpriv->path); 514 monpriv->path = NULL; 515 out: 516 atomic_set(&monpriv->iucv_severed, 1); 517 return rc; 518 } 519 520 static int monreader_restore(struct device *dev) 521 { 522 int rc; 523 524 segment_unload(mon_dcss_name); 525 rc = segment_load(mon_dcss_name, SEGMENT_SHARED, 526 &mon_dcss_start, &mon_dcss_end); 527 if (rc < 0) { 528 segment_warning(rc, mon_dcss_name); 529 panic("fatal monreader resume error: no monitor dcss\n"); 530 } 531 return monreader_thaw(dev); 532 } 533 534 static const struct dev_pm_ops monreader_pm_ops = { 535 .freeze = monreader_freeze, 536 .thaw = monreader_thaw, 537 .restore = monreader_restore, 538 }; 539 540 static struct device_driver monreader_driver = { 541 .name = "monreader", 542 .bus = &iucv_bus, 543 .pm = &monreader_pm_ops, 544 }; 545 546 547 /****************************************************************************** 548 * module init/exit * 549 *****************************************************************************/ 550 static int __init mon_init(void) 551 { 552 int rc; 553 554 if (!MACHINE_IS_VM) { 555 pr_err("The z/VM *MONITOR record device driver cannot be " 556 "loaded without z/VM\n"); 557 return -ENODEV; 558 } 559 560 /* 561 * Register with IUCV and connect to *MONITOR service 562 */ 563 rc = iucv_register(&monreader_iucv_handler, 1); 564 if (rc) { 565 pr_err("The z/VM *MONITOR record device driver failed to " 566 "register with IUCV\n"); 567 return rc; 568 } 569 570 rc = driver_register(&monreader_driver); 571 if (rc) 572 goto out_iucv; 573 monreader_device = kzalloc(sizeof(struct device), GFP_KERNEL); 574 if (!monreader_device) { 575 rc = -ENOMEM; 576 goto out_driver; 577 } 578 579 dev_set_name(monreader_device, "monreader-dev"); 580 monreader_device->bus = &iucv_bus; 581 monreader_device->parent = iucv_root; 582 monreader_device->driver = &monreader_driver; 583 monreader_device->release = (void (*)(struct device *))kfree; 584 rc = device_register(monreader_device); 585 if (rc) { 586 put_device(monreader_device); 587 goto out_driver; 588 } 589 590 rc = segment_type(mon_dcss_name); 591 if (rc < 0) { 592 segment_warning(rc, mon_dcss_name); 593 goto out_device; 594 } 595 if (rc != SEG_TYPE_SC) { 596 pr_err("The specified *MONITOR DCSS %s does not have the " 597 "required type SC\n", mon_dcss_name); 598 rc = -EINVAL; 599 goto out_device; 600 } 601 602 rc = segment_load(mon_dcss_name, SEGMENT_SHARED, 603 &mon_dcss_start, &mon_dcss_end); 604 if (rc < 0) { 605 segment_warning(rc, mon_dcss_name); 606 rc = -EINVAL; 607 goto out_device; 608 } 609 dcss_mkname(mon_dcss_name, &user_data_connect[8]); 610 611 /* 612 * misc_register() has to be the last action in module_init(), because 613 * file operations will be available right after this. 614 */ 615 rc = misc_register(&mon_dev); 616 if (rc < 0 ) 617 goto out; 618 return 0; 619 620 out: 621 segment_unload(mon_dcss_name); 622 out_device: 623 device_unregister(monreader_device); 624 out_driver: 625 driver_unregister(&monreader_driver); 626 out_iucv: 627 iucv_unregister(&monreader_iucv_handler, 1); 628 return rc; 629 } 630 631 static void __exit mon_exit(void) 632 { 633 segment_unload(mon_dcss_name); 634 misc_deregister(&mon_dev); 635 device_unregister(monreader_device); 636 driver_unregister(&monreader_driver); 637 iucv_unregister(&monreader_iucv_handler, 1); 638 return; 639 } 640 641 642 module_init(mon_init); 643 module_exit(mon_exit); 644 645 module_param_string(mondcss, mon_dcss_name, 9, 0444); 646 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR " 647 "service, max. 8 chars. Default is MONDCSS"); 648 649 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>"); 650 MODULE_DESCRIPTION("Character device driver for reading z/VM " 651 "monitor service records."); 652 MODULE_LICENSE("GPL"); 653