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 pr_fmt(fmt) "monreader: " fmt 11 12 #include <linux/module.h> 13 #include <linux/moduleparam.h> 14 #include <linux/init.h> 15 #include <linux/errno.h> 16 #include <linux/types.h> 17 #include <linux/kernel.h> 18 #include <linux/miscdevice.h> 19 #include <linux/ctype.h> 20 #include <linux/spinlock.h> 21 #include <linux/interrupt.h> 22 #include <linux/poll.h> 23 #include <linux/slab.h> 24 #include <net/iucv/iucv.h> 25 #include <linux/uaccess.h> 26 #include <asm/machine.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 *)__va(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 *)(__va(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 *)(__va(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_obj(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_obj(struct mon_msg, GFP_KERNEL); 189 if (!monpriv->msg_array[i]) { 190 mon_free_mem(monpriv); 191 return NULL; 192 } 193 } 194 return monpriv; 195 } 196 197 static inline void mon_next_mca(struct mon_msg *monmsg) 198 { 199 if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12)) 200 return; 201 monmsg->mca_offset += 12; 202 monmsg->pos = 0; 203 } 204 205 static struct mon_msg *mon_next_message(struct mon_private *monpriv) 206 { 207 struct mon_msg *monmsg; 208 209 if (!atomic_read(&monpriv->read_ready)) 210 return NULL; 211 monmsg = monpriv->msg_array[monpriv->read_index]; 212 if (unlikely(monmsg->replied_msglim)) { 213 monmsg->replied_msglim = 0; 214 monmsg->msglim_reached = 0; 215 monmsg->pos = 0; 216 monmsg->mca_offset = 0; 217 monpriv->read_index = (monpriv->read_index + 1) % 218 MON_MSGLIM; 219 atomic_dec(&monpriv->read_ready); 220 return ERR_PTR(-EOVERFLOW); 221 } 222 return monmsg; 223 } 224 225 226 /****************************************************************************** 227 * IUCV handler * 228 *****************************************************************************/ 229 static void mon_iucv_path_complete(struct iucv_path *path, u8 *ipuser) 230 { 231 struct mon_private *monpriv = path->private; 232 233 atomic_set(&monpriv->iucv_connected, 1); 234 wake_up(&mon_conn_wait_queue); 235 } 236 237 static void mon_iucv_path_severed(struct iucv_path *path, u8 *ipuser) 238 { 239 struct mon_private *monpriv = path->private; 240 241 pr_err("z/VM *MONITOR system service disconnected with rc=%i\n", 242 ipuser[0]); 243 iucv_path_sever(path, NULL); 244 atomic_set(&monpriv->iucv_severed, 1); 245 wake_up(&mon_conn_wait_queue); 246 wake_up_interruptible(&mon_read_wait_queue); 247 } 248 249 static void mon_iucv_message_pending(struct iucv_path *path, 250 struct iucv_message *msg) 251 { 252 struct mon_private *monpriv = path->private; 253 254 memcpy(&monpriv->msg_array[monpriv->write_index]->msg, 255 msg, sizeof(*msg)); 256 if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) { 257 pr_warn("The read queue for monitor data is full\n"); 258 monpriv->msg_array[monpriv->write_index]->msglim_reached = 1; 259 } 260 monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM; 261 atomic_inc(&monpriv->read_ready); 262 wake_up_interruptible(&mon_read_wait_queue); 263 } 264 265 static struct iucv_handler monreader_iucv_handler = { 266 .path_complete = mon_iucv_path_complete, 267 .path_severed = mon_iucv_path_severed, 268 .message_pending = mon_iucv_message_pending, 269 }; 270 271 /****************************************************************************** 272 * file operations * 273 *****************************************************************************/ 274 static int mon_open(struct inode *inode, struct file *filp) 275 { 276 struct mon_private *monpriv; 277 int rc; 278 279 /* 280 * only one user allowed 281 */ 282 rc = -EBUSY; 283 if (test_and_set_bit(MON_IN_USE, &mon_in_use)) 284 goto out; 285 286 rc = -ENOMEM; 287 monpriv = mon_alloc_mem(); 288 if (!monpriv) 289 goto out_use; 290 291 /* 292 * Connect to *MONITOR service 293 */ 294 monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL); 295 if (!monpriv->path) 296 goto out_priv; 297 rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler, 298 MON_SERVICE, NULL, user_data_connect, monpriv); 299 if (rc) { 300 pr_err("Connecting to the z/VM *MONITOR system service " 301 "failed with rc=%i\n", rc); 302 rc = -EIO; 303 goto out_path; 304 } 305 /* 306 * Wait for connection confirmation 307 */ 308 wait_event(mon_conn_wait_queue, 309 atomic_read(&monpriv->iucv_connected) || 310 atomic_read(&monpriv->iucv_severed)); 311 if (atomic_read(&monpriv->iucv_severed)) { 312 atomic_set(&monpriv->iucv_severed, 0); 313 atomic_set(&monpriv->iucv_connected, 0); 314 rc = -EIO; 315 goto out_path; 316 } 317 filp->private_data = monpriv; 318 return nonseekable_open(inode, filp); 319 320 out_path: 321 iucv_path_free(monpriv->path); 322 out_priv: 323 mon_free_mem(monpriv); 324 out_use: 325 clear_bit(MON_IN_USE, &mon_in_use); 326 out: 327 return rc; 328 } 329 330 static int mon_close(struct inode *inode, struct file *filp) 331 { 332 int rc, i; 333 struct mon_private *monpriv = filp->private_data; 334 335 /* 336 * Close IUCV connection and unregister 337 */ 338 if (monpriv->path) { 339 rc = iucv_path_sever(monpriv->path, user_data_sever); 340 if (rc) 341 pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n", 342 rc); 343 iucv_path_free(monpriv->path); 344 } 345 346 atomic_set(&monpriv->iucv_severed, 0); 347 atomic_set(&monpriv->iucv_connected, 0); 348 atomic_set(&monpriv->read_ready, 0); 349 atomic_set(&monpriv->msglim_count, 0); 350 monpriv->write_index = 0; 351 monpriv->read_index = 0; 352 353 for (i = 0; i < MON_MSGLIM; i++) 354 kfree(monpriv->msg_array[i]); 355 kfree(monpriv); 356 clear_bit(MON_IN_USE, &mon_in_use); 357 return 0; 358 } 359 360 static ssize_t mon_read(struct file *filp, char __user *data, 361 size_t count, loff_t *ppos) 362 { 363 struct mon_private *monpriv = filp->private_data; 364 struct mon_msg *monmsg; 365 int ret; 366 u32 mce_start; 367 368 monmsg = mon_next_message(monpriv); 369 if (IS_ERR(monmsg)) 370 return PTR_ERR(monmsg); 371 372 if (!monmsg) { 373 if (filp->f_flags & O_NONBLOCK) 374 return -EAGAIN; 375 ret = wait_event_interruptible(mon_read_wait_queue, 376 atomic_read(&monpriv->read_ready) || 377 atomic_read(&monpriv->iucv_severed)); 378 if (ret) 379 return ret; 380 if (unlikely(atomic_read(&monpriv->iucv_severed))) 381 return -EIO; 382 monmsg = monpriv->msg_array[monpriv->read_index]; 383 } 384 385 if (!monmsg->pos) 386 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset; 387 if (mon_check_mca(monmsg)) 388 goto reply; 389 390 /* read monitor control element (12 bytes) first */ 391 mce_start = mon_mca_start(monmsg) + monmsg->mca_offset; 392 if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) { 393 count = min(count, (size_t) mce_start + 12 - monmsg->pos); 394 ret = copy_to_user(data, __va(monmsg->pos), count); 395 if (ret) 396 return -EFAULT; 397 monmsg->pos += count; 398 if (monmsg->pos == mce_start + 12) 399 monmsg->pos = mon_rec_start(monmsg); 400 goto out_copy; 401 } 402 403 /* read records */ 404 if (monmsg->pos <= mon_rec_end(monmsg)) { 405 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos 406 + 1); 407 ret = copy_to_user(data, __va(monmsg->pos), count); 408 if (ret) 409 return -EFAULT; 410 monmsg->pos += count; 411 if (monmsg->pos > mon_rec_end(monmsg)) 412 mon_next_mca(monmsg); 413 goto out_copy; 414 } 415 reply: 416 ret = mon_send_reply(monmsg, monpriv); 417 return ret; 418 419 out_copy: 420 *ppos += count; 421 return count; 422 } 423 424 static __poll_t mon_poll(struct file *filp, struct poll_table_struct *p) 425 { 426 struct mon_private *monpriv = filp->private_data; 427 428 poll_wait(filp, &mon_read_wait_queue, p); 429 if (unlikely(atomic_read(&monpriv->iucv_severed))) 430 return EPOLLERR; 431 if (atomic_read(&monpriv->read_ready)) 432 return EPOLLIN | EPOLLRDNORM; 433 return 0; 434 } 435 436 static const struct file_operations mon_fops = { 437 .owner = THIS_MODULE, 438 .open = &mon_open, 439 .release = &mon_close, 440 .read = &mon_read, 441 .poll = &mon_poll, 442 .llseek = noop_llseek, 443 }; 444 445 static struct miscdevice mon_dev = { 446 .name = "monreader", 447 .fops = &mon_fops, 448 .minor = MISC_DYNAMIC_MINOR, 449 }; 450 451 /****************************************************************************** 452 * module init/exit * 453 *****************************************************************************/ 454 static int __init mon_init(void) 455 { 456 int rc; 457 458 if (!machine_is_vm()) { 459 pr_err("The z/VM *MONITOR record device driver cannot be " 460 "loaded without z/VM\n"); 461 return -ENODEV; 462 } 463 464 /* 465 * Register with IUCV and connect to *MONITOR service 466 */ 467 rc = iucv_register(&monreader_iucv_handler, 1); 468 if (rc) { 469 pr_err("The z/VM *MONITOR record device driver failed to " 470 "register with IUCV\n"); 471 return rc; 472 } 473 474 rc = segment_type(mon_dcss_name); 475 if (rc < 0) { 476 segment_warning(rc, mon_dcss_name); 477 goto out_iucv; 478 } 479 if (rc != SEG_TYPE_SC) { 480 pr_err("The specified *MONITOR DCSS %s does not have the " 481 "required type SC\n", mon_dcss_name); 482 rc = -EINVAL; 483 goto out_iucv; 484 } 485 486 rc = segment_load(mon_dcss_name, SEGMENT_SHARED, 487 &mon_dcss_start, &mon_dcss_end); 488 if (rc < 0) { 489 segment_warning(rc, mon_dcss_name); 490 rc = -EINVAL; 491 goto out_iucv; 492 } 493 dcss_mkname(mon_dcss_name, &user_data_connect[8]); 494 495 /* 496 * misc_register() has to be the last action in module_init(), because 497 * file operations will be available right after this. 498 */ 499 rc = misc_register(&mon_dev); 500 if (rc < 0 ) 501 goto out; 502 return 0; 503 504 out: 505 segment_unload(mon_dcss_name); 506 out_iucv: 507 iucv_unregister(&monreader_iucv_handler, 1); 508 return rc; 509 } 510 511 static void __exit mon_exit(void) 512 { 513 segment_unload(mon_dcss_name); 514 misc_deregister(&mon_dev); 515 iucv_unregister(&monreader_iucv_handler, 1); 516 return; 517 } 518 519 520 module_init(mon_init); 521 module_exit(mon_exit); 522 523 module_param_string(mondcss, mon_dcss_name, 9, 0444); 524 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR " 525 "service, max. 8 chars. Default is MONDCSS"); 526 527 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>"); 528 MODULE_DESCRIPTION("Character device driver for reading z/VM " 529 "monitor service records."); 530 MODULE_LICENSE("GPL"); 531