1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) 4 * Copyright (C) 2001 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com) 5 */ 6 7 #include <linux/console.h> 8 #include <linux/ctype.h> 9 #include <linux/string.h> 10 #include <linux/interrupt.h> 11 #include <linux/list.h> 12 #include <linux/mm.h> 13 #include <linux/module.h> 14 #include <linux/notifier.h> 15 #include <linux/panic_notifier.h> 16 #include <linux/reboot.h> 17 #include <linux/sched/debug.h> 18 #include <linux/proc_fs.h> 19 #include <linux/slab.h> 20 #include <linux/syscalls.h> 21 #include <linux/utsname.h> 22 #include <linux/socket.h> 23 #include <linux/un.h> 24 #include <linux/workqueue.h> 25 #include <linux/mutex.h> 26 #include <linux/fs.h> 27 #include <linux/mount.h> 28 #include <linux/file.h> 29 #include <linux/uaccess.h> 30 #include <asm/switch_to.h> 31 32 #include <init.h> 33 #include <irq_kern.h> 34 #include <irq_user.h> 35 #include <kern_util.h> 36 #include "mconsole.h" 37 #include "mconsole_kern.h" 38 #include <os.h> 39 40 static struct vfsmount *proc_mnt = NULL; 41 42 static int do_unlink_socket(struct notifier_block *notifier, 43 unsigned long what, void *data) 44 { 45 return mconsole_unlink_socket(); 46 } 47 48 49 static struct notifier_block reboot_notifier = { 50 .notifier_call = do_unlink_socket, 51 .priority = 0, 52 }; 53 54 /* Safe without explicit locking for now. Tasklets provide their own 55 * locking, and the interrupt handler is safe because it can't interrupt 56 * itself and it can only happen on CPU 0. 57 */ 58 59 static LIST_HEAD(mc_requests); 60 61 static void mc_work_proc(struct work_struct *unused) 62 { 63 struct mconsole_entry *req; 64 unsigned long flags; 65 66 while (!list_empty(&mc_requests)) { 67 local_irq_save(flags); 68 req = list_entry(mc_requests.next, struct mconsole_entry, list); 69 list_del(&req->list); 70 local_irq_restore(flags); 71 req->request.cmd->handler(&req->request); 72 kfree(req); 73 } 74 } 75 76 static DECLARE_WORK(mconsole_work, mc_work_proc); 77 78 static irqreturn_t mconsole_interrupt(int irq, void *dev_id) 79 { 80 /* long to avoid size mismatch warnings from gcc */ 81 long fd; 82 struct mconsole_entry *new; 83 static struct mc_request req; /* that's OK */ 84 85 fd = (long) dev_id; 86 while (mconsole_get_request(fd, &req)) { 87 if (req.cmd->context == MCONSOLE_INTR) 88 (*req.cmd->handler)(&req); 89 else { 90 new = kmalloc(sizeof(*new), GFP_NOWAIT); 91 if (new == NULL) 92 mconsole_reply(&req, "Out of memory", 1, 0); 93 else { 94 new->request = req; 95 new->request.regs = get_irq_regs()->regs; 96 list_add(&new->list, &mc_requests); 97 } 98 } 99 } 100 if (!list_empty(&mc_requests)) 101 schedule_work(&mconsole_work); 102 return IRQ_HANDLED; 103 } 104 105 void mconsole_version(struct mc_request *req) 106 { 107 char version[256]; 108 109 sprintf(version, "%s %s %s %s %s", utsname()->sysname, 110 utsname()->nodename, utsname()->release, utsname()->version, 111 utsname()->machine); 112 mconsole_reply(req, version, 0, 0); 113 } 114 115 void mconsole_log(struct mc_request *req) 116 { 117 int len; 118 char *ptr = req->request.data; 119 120 ptr += strlen("log "); 121 122 len = req->len - (ptr - req->request.data); 123 printk(KERN_WARNING "%.*s", len, ptr); 124 mconsole_reply(req, "", 0, 0); 125 } 126 127 void mconsole_proc(struct mc_request *req) 128 { 129 struct vfsmount *mnt = proc_mnt; 130 char *buf; 131 int len; 132 struct file *file; 133 int first_chunk = 1; 134 char *ptr = req->request.data; 135 loff_t pos = 0; 136 137 ptr += strlen("proc"); 138 ptr = skip_spaces(ptr); 139 140 if (!mnt) { 141 mconsole_reply(req, "Proc not available", 1, 0); 142 goto out; 143 } 144 file = file_open_root_mnt(mnt, ptr, O_RDONLY, 0); 145 if (IS_ERR(file)) { 146 mconsole_reply(req, "Failed to open file", 1, 0); 147 printk(KERN_ERR "open /proc/%s: %ld\n", ptr, PTR_ERR(file)); 148 goto out; 149 } 150 151 buf = kmalloc(PAGE_SIZE, GFP_KERNEL); 152 if (buf == NULL) { 153 mconsole_reply(req, "Failed to allocate buffer", 1, 0); 154 goto out_fput; 155 } 156 157 do { 158 len = kernel_read(file, buf, PAGE_SIZE - 1, &pos); 159 if (len < 0) { 160 mconsole_reply(req, "Read of file failed", 1, 0); 161 goto out_free; 162 } 163 /* Begin the file content on his own line. */ 164 if (first_chunk) { 165 mconsole_reply(req, "\n", 0, 1); 166 first_chunk = 0; 167 } 168 buf[len] = '\0'; 169 mconsole_reply(req, buf, 0, (len > 0)); 170 } while (len > 0); 171 out_free: 172 kfree(buf); 173 out_fput: 174 fput(file); 175 out: ; 176 } 177 178 #define UML_MCONSOLE_HELPTEXT \ 179 "Commands: \n\ 180 version - Get kernel version \n\ 181 help - Print this message \n\ 182 halt - Halt UML \n\ 183 reboot - Reboot UML \n\ 184 config <dev>=<config> - Add a new device to UML; \n\ 185 same syntax as command line \n\ 186 config <dev> - Query the configuration of a device \n\ 187 remove <dev> - Remove a device from UML \n\ 188 sysrq <letter> - Performs the SysRq action controlled by the letter \n\ 189 cad - invoke the Ctrl-Alt-Del handler \n\ 190 stop - pause the UML; it will do nothing until it receives a 'go' \n\ 191 go - continue the UML after a 'stop' \n\ 192 log <string> - make UML enter <string> into the kernel log\n\ 193 proc <file> - returns the contents of the UML's /proc/<file>\n\ 194 stack <pid> - returns the stack of the specified pid\n\ 195 " 196 197 void mconsole_help(struct mc_request *req) 198 { 199 mconsole_reply(req, UML_MCONSOLE_HELPTEXT, 0, 0); 200 } 201 202 void mconsole_halt(struct mc_request *req) 203 { 204 mconsole_reply(req, "", 0, 0); 205 machine_halt(); 206 } 207 208 void mconsole_reboot(struct mc_request *req) 209 { 210 mconsole_reply(req, "", 0, 0); 211 machine_restart(NULL); 212 } 213 214 void mconsole_cad(struct mc_request *req) 215 { 216 mconsole_reply(req, "", 0, 0); 217 ctrl_alt_del(); 218 } 219 220 void mconsole_go(struct mc_request *req) 221 { 222 mconsole_reply(req, "Not stopped", 1, 0); 223 } 224 225 void mconsole_stop(struct mc_request *req) 226 { 227 deactivate_fd(req->originating_fd, MCONSOLE_IRQ); 228 os_set_fd_block(req->originating_fd, 1); 229 mconsole_reply(req, "stopped", 0, 0); 230 for (;;) { 231 if (!mconsole_get_request(req->originating_fd, req)) 232 continue; 233 if (req->cmd->handler == mconsole_go) 234 break; 235 if (req->cmd->handler == mconsole_stop) { 236 mconsole_reply(req, "Already stopped", 1, 0); 237 continue; 238 } 239 if (req->cmd->handler == mconsole_sysrq) { 240 struct pt_regs *old_regs; 241 old_regs = set_irq_regs((struct pt_regs *)&req->regs); 242 mconsole_sysrq(req); 243 set_irq_regs(old_regs); 244 continue; 245 } 246 (*req->cmd->handler)(req); 247 } 248 os_set_fd_block(req->originating_fd, 0); 249 mconsole_reply(req, "", 0, 0); 250 } 251 252 static DEFINE_SPINLOCK(mc_devices_lock); 253 static LIST_HEAD(mconsole_devices); 254 255 void mconsole_register_dev(struct mc_device *new) 256 { 257 spin_lock(&mc_devices_lock); 258 BUG_ON(!list_empty(&new->list)); 259 list_add(&new->list, &mconsole_devices); 260 spin_unlock(&mc_devices_lock); 261 } 262 263 static struct mc_device *mconsole_find_dev(char *name) 264 { 265 struct list_head *ele; 266 struct mc_device *dev; 267 268 list_for_each(ele, &mconsole_devices) { 269 dev = list_entry(ele, struct mc_device, list); 270 if (!strncmp(name, dev->name, strlen(dev->name))) 271 return dev; 272 } 273 return NULL; 274 } 275 276 #define UNPLUGGED_PER_PAGE \ 277 ((PAGE_SIZE - sizeof(struct list_head)) / sizeof(unsigned long)) 278 279 struct unplugged_pages { 280 struct list_head list; 281 void *pages[UNPLUGGED_PER_PAGE]; 282 }; 283 284 static DEFINE_MUTEX(plug_mem_mutex); 285 static unsigned long long unplugged_pages_count = 0; 286 static LIST_HEAD(unplugged_pages); 287 static int unplug_index = UNPLUGGED_PER_PAGE; 288 289 static int mem_config(char *str, char **error_out) 290 { 291 unsigned long long diff; 292 int err = -EINVAL, i, add; 293 char *ret; 294 295 if (str[0] != '=') { 296 *error_out = "Expected '=' after 'mem'"; 297 goto out; 298 } 299 300 str++; 301 if (str[0] == '-') 302 add = 0; 303 else if (str[0] == '+') { 304 add = 1; 305 } 306 else { 307 *error_out = "Expected increment to start with '-' or '+'"; 308 goto out; 309 } 310 311 str++; 312 diff = memparse(str, &ret); 313 if (*ret != '\0') { 314 *error_out = "Failed to parse memory increment"; 315 goto out; 316 } 317 318 diff /= PAGE_SIZE; 319 320 mutex_lock(&plug_mem_mutex); 321 for (i = 0; i < diff; i++) { 322 struct unplugged_pages *unplugged; 323 void *addr; 324 325 if (add) { 326 if (list_empty(&unplugged_pages)) 327 break; 328 329 unplugged = list_entry(unplugged_pages.next, 330 struct unplugged_pages, list); 331 if (unplug_index > 0) 332 addr = unplugged->pages[--unplug_index]; 333 else { 334 list_del(&unplugged->list); 335 addr = unplugged; 336 unplug_index = UNPLUGGED_PER_PAGE; 337 } 338 339 free_page((unsigned long) addr); 340 unplugged_pages_count--; 341 } 342 else { 343 struct page *page; 344 345 page = alloc_page(GFP_ATOMIC); 346 if (page == NULL) 347 break; 348 349 unplugged = page_address(page); 350 if (unplug_index == UNPLUGGED_PER_PAGE) { 351 list_add(&unplugged->list, &unplugged_pages); 352 unplug_index = 0; 353 } 354 else { 355 struct list_head *entry = unplugged_pages.next; 356 addr = unplugged; 357 358 unplugged = list_entry(entry, 359 struct unplugged_pages, 360 list); 361 err = os_drop_memory(addr, PAGE_SIZE); 362 if (err) { 363 printk(KERN_ERR "Failed to release " 364 "memory - errno = %d\n", err); 365 *error_out = "Failed to release memory"; 366 goto out_unlock; 367 } 368 unplugged->pages[unplug_index++] = addr; 369 } 370 371 unplugged_pages_count++; 372 } 373 } 374 375 err = 0; 376 out_unlock: 377 mutex_unlock(&plug_mem_mutex); 378 out: 379 return err; 380 } 381 382 static int mem_get_config(char *name, char *str, int size, char **error_out) 383 { 384 char buf[sizeof("18446744073709551615")]; 385 int len = 0; 386 387 sprintf(buf, "%ld", uml_physmem); 388 CONFIG_CHUNK(str, size, len, buf, 1); 389 390 return len; 391 } 392 393 static int mem_id(char **str, int *start_out, int *end_out) 394 { 395 *start_out = 0; 396 *end_out = 0; 397 398 return 0; 399 } 400 401 static int mem_remove(int n, char **error_out) 402 { 403 *error_out = "Memory doesn't support the remove operation"; 404 return -EBUSY; 405 } 406 407 static struct mc_device mem_mc = { 408 .list = LIST_HEAD_INIT(mem_mc.list), 409 .name = "mem", 410 .config = mem_config, 411 .get_config = mem_get_config, 412 .id = mem_id, 413 .remove = mem_remove, 414 }; 415 416 static int __init mem_mc_init(void) 417 { 418 if (can_drop_memory()) 419 mconsole_register_dev(&mem_mc); 420 else printk(KERN_ERR "Can't release memory to the host - memory " 421 "hotplug won't be supported\n"); 422 return 0; 423 } 424 425 __initcall(mem_mc_init); 426 427 #define CONFIG_BUF_SIZE 64 428 429 static void mconsole_get_config(int (*get_config)(char *, char *, int, 430 char **), 431 struct mc_request *req, char *name) 432 { 433 char default_buf[CONFIG_BUF_SIZE], *error, *buf; 434 int n, size; 435 436 if (get_config == NULL) { 437 mconsole_reply(req, "No get_config routine defined", 1, 0); 438 return; 439 } 440 441 error = NULL; 442 size = ARRAY_SIZE(default_buf); 443 buf = default_buf; 444 445 while (1) { 446 n = (*get_config)(name, buf, size, &error); 447 if (error != NULL) { 448 mconsole_reply(req, error, 1, 0); 449 goto out; 450 } 451 452 if (n <= size) { 453 mconsole_reply(req, buf, 0, 0); 454 goto out; 455 } 456 457 if (buf != default_buf) 458 kfree(buf); 459 460 size = n; 461 buf = kmalloc(size, GFP_KERNEL); 462 if (buf == NULL) { 463 mconsole_reply(req, "Failed to allocate buffer", 1, 0); 464 return; 465 } 466 } 467 out: 468 if (buf != default_buf) 469 kfree(buf); 470 } 471 472 void mconsole_config(struct mc_request *req) 473 { 474 struct mc_device *dev; 475 char *ptr = req->request.data, *name, *error_string = ""; 476 int err; 477 478 ptr += strlen("config"); 479 ptr = skip_spaces(ptr); 480 dev = mconsole_find_dev(ptr); 481 if (dev == NULL) { 482 mconsole_reply(req, "Bad configuration option", 1, 0); 483 return; 484 } 485 486 name = &ptr[strlen(dev->name)]; 487 ptr = name; 488 while ((*ptr != '=') && (*ptr != '\0')) 489 ptr++; 490 491 if (*ptr == '=') { 492 err = (*dev->config)(name, &error_string); 493 mconsole_reply(req, error_string, err, 0); 494 } 495 else mconsole_get_config(dev->get_config, req, name); 496 } 497 498 void mconsole_remove(struct mc_request *req) 499 { 500 struct mc_device *dev; 501 char *ptr = req->request.data, *err_msg = ""; 502 char error[256]; 503 int err, start, end, n; 504 505 ptr += strlen("remove"); 506 ptr = skip_spaces(ptr); 507 dev = mconsole_find_dev(ptr); 508 if (dev == NULL) { 509 mconsole_reply(req, "Bad remove option", 1, 0); 510 return; 511 } 512 513 ptr = &ptr[strlen(dev->name)]; 514 515 err = 1; 516 n = (*dev->id)(&ptr, &start, &end); 517 if (n < 0) { 518 err_msg = "Couldn't parse device number"; 519 goto out; 520 } 521 else if ((n < start) || (n > end)) { 522 sprintf(error, "Invalid device number - must be between " 523 "%d and %d", start, end); 524 err_msg = error; 525 goto out; 526 } 527 528 err_msg = NULL; 529 err = (*dev->remove)(n, &err_msg); 530 switch(err) { 531 case 0: 532 err_msg = ""; 533 break; 534 case -ENODEV: 535 if (err_msg == NULL) 536 err_msg = "Device doesn't exist"; 537 break; 538 case -EBUSY: 539 if (err_msg == NULL) 540 err_msg = "Device is currently open"; 541 break; 542 default: 543 break; 544 } 545 out: 546 mconsole_reply(req, err_msg, err, 0); 547 } 548 549 struct mconsole_output { 550 struct list_head list; 551 struct mc_request *req; 552 }; 553 554 static DEFINE_SPINLOCK(client_lock); 555 static LIST_HEAD(clients); 556 static char console_buf[MCONSOLE_MAX_DATA]; 557 558 static void console_write(struct console *console, const char *string, 559 unsigned int len) 560 { 561 struct list_head *ele; 562 int n; 563 564 if (list_empty(&clients)) 565 return; 566 567 while (len > 0) { 568 n = min((size_t) len, ARRAY_SIZE(console_buf)); 569 strncpy(console_buf, string, n); 570 string += n; 571 len -= n; 572 573 list_for_each(ele, &clients) { 574 struct mconsole_output *entry; 575 576 entry = list_entry(ele, struct mconsole_output, list); 577 mconsole_reply_len(entry->req, console_buf, n, 0, 1); 578 } 579 } 580 } 581 582 static struct console mc_console = { .name = "mc", 583 .write = console_write, 584 .flags = CON_ENABLED, 585 .index = -1 }; 586 587 static int mc_add_console(void) 588 { 589 register_console(&mc_console); 590 return 0; 591 } 592 593 late_initcall(mc_add_console); 594 595 static void with_console(struct mc_request *req, void (*proc)(void *), 596 void *arg) 597 { 598 struct mconsole_output entry; 599 unsigned long flags; 600 601 entry.req = req; 602 spin_lock_irqsave(&client_lock, flags); 603 list_add(&entry.list, &clients); 604 spin_unlock_irqrestore(&client_lock, flags); 605 606 (*proc)(arg); 607 608 mconsole_reply_len(req, "", 0, 0, 0); 609 610 spin_lock_irqsave(&client_lock, flags); 611 list_del(&entry.list); 612 spin_unlock_irqrestore(&client_lock, flags); 613 } 614 615 #ifdef CONFIG_MAGIC_SYSRQ 616 617 #include <linux/sysrq.h> 618 619 static void sysrq_proc(void *arg) 620 { 621 char *op = arg; 622 handle_sysrq(*op); 623 } 624 625 void mconsole_sysrq(struct mc_request *req) 626 { 627 char *ptr = req->request.data; 628 629 ptr += strlen("sysrq"); 630 ptr = skip_spaces(ptr); 631 632 /* 633 * With 'b', the system will shut down without a chance to reply, 634 * so in this case, we reply first. 635 */ 636 if (*ptr == 'b') 637 mconsole_reply(req, "", 0, 0); 638 639 with_console(req, sysrq_proc, ptr); 640 } 641 #else 642 void mconsole_sysrq(struct mc_request *req) 643 { 644 mconsole_reply(req, "Sysrq not compiled in", 1, 0); 645 } 646 #endif 647 648 static void stack_proc(void *arg) 649 { 650 struct task_struct *task = arg; 651 652 show_stack(task, NULL, KERN_INFO); 653 } 654 655 /* 656 * Mconsole stack trace 657 * Added by Allan Graves, Jeff Dike 658 * Dumps a stacks registers to the linux console. 659 * Usage stack <pid>. 660 */ 661 void mconsole_stack(struct mc_request *req) 662 { 663 char *ptr = req->request.data; 664 int pid_requested= -1; 665 struct task_struct *to = NULL; 666 667 /* 668 * Would be nice: 669 * 1) Send showregs output to mconsole. 670 * 2) Add a way to stack dump all pids. 671 */ 672 673 ptr += strlen("stack"); 674 ptr = skip_spaces(ptr); 675 676 /* 677 * Should really check for multiple pids or reject bad args here 678 */ 679 /* What do the arguments in mconsole_reply mean? */ 680 if (sscanf(ptr, "%d", &pid_requested) == 0) { 681 mconsole_reply(req, "Please specify a pid", 1, 0); 682 return; 683 } 684 685 to = find_task_by_pid_ns(pid_requested, &init_pid_ns); 686 if ((to == NULL) || (pid_requested == 0)) { 687 mconsole_reply(req, "Couldn't find that pid", 1, 0); 688 return; 689 } 690 with_console(req, stack_proc, to); 691 } 692 693 static int __init mount_proc(void) 694 { 695 struct file_system_type *proc_fs_type; 696 struct vfsmount *mnt; 697 698 proc_fs_type = get_fs_type("proc"); 699 if (!proc_fs_type) 700 return -ENODEV; 701 702 mnt = kern_mount(proc_fs_type); 703 put_filesystem(proc_fs_type); 704 if (IS_ERR(mnt)) 705 return PTR_ERR(mnt); 706 707 proc_mnt = mnt; 708 return 0; 709 } 710 711 /* 712 * Changed by mconsole_setup, which is __setup, and called before SMP is 713 * active. 714 */ 715 static char *notify_socket = NULL; 716 717 static int __init mconsole_init(void) 718 { 719 /* long to avoid size mismatch warnings from gcc */ 720 long sock; 721 int err; 722 char file[UNIX_PATH_MAX]; 723 724 mount_proc(); 725 726 if (umid_file_name("mconsole", file, sizeof(file))) 727 return -1; 728 snprintf(mconsole_socket_name, sizeof(file), "%s", file); 729 730 sock = os_create_unix_socket(file, sizeof(file), 1); 731 if (sock < 0) { 732 printk(KERN_ERR "Failed to initialize management console\n"); 733 return 1; 734 } 735 if (os_set_fd_block(sock, 0)) 736 goto out; 737 738 register_reboot_notifier(&reboot_notifier); 739 740 err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt, 741 IRQF_SHARED, "mconsole", (void *)sock); 742 if (err < 0) { 743 printk(KERN_ERR "Failed to get IRQ for management console\n"); 744 goto out; 745 } 746 747 if (notify_socket != NULL) { 748 notify_socket = kstrdup(notify_socket, GFP_KERNEL); 749 if (notify_socket != NULL) 750 mconsole_notify(notify_socket, MCONSOLE_SOCKET, 751 mconsole_socket_name, 752 strlen(mconsole_socket_name) + 1); 753 else printk(KERN_ERR "mconsole_setup failed to strdup " 754 "string\n"); 755 } 756 757 printk(KERN_INFO "mconsole (version %d) initialized on %s\n", 758 MCONSOLE_VERSION, mconsole_socket_name); 759 return 0; 760 761 out: 762 os_close_file(sock); 763 return 1; 764 } 765 766 __initcall(mconsole_init); 767 768 static ssize_t mconsole_proc_write(struct file *file, 769 const char __user *buffer, size_t count, loff_t *pos) 770 { 771 char *buf; 772 773 buf = memdup_user_nul(buffer, count); 774 if (IS_ERR(buf)) 775 return PTR_ERR(buf); 776 777 mconsole_notify(notify_socket, MCONSOLE_USER_NOTIFY, buf, count); 778 kfree(buf); 779 return count; 780 } 781 782 static const struct proc_ops mconsole_proc_ops = { 783 .proc_write = mconsole_proc_write, 784 .proc_lseek = noop_llseek, 785 }; 786 787 static int create_proc_mconsole(void) 788 { 789 struct proc_dir_entry *ent; 790 791 if (notify_socket == NULL) 792 return 0; 793 794 ent = proc_create("mconsole", 0200, NULL, &mconsole_proc_ops); 795 if (ent == NULL) { 796 printk(KERN_INFO "create_proc_mconsole : proc_create failed\n"); 797 return 0; 798 } 799 return 0; 800 } 801 802 static DEFINE_SPINLOCK(notify_spinlock); 803 804 void lock_notify(void) 805 { 806 spin_lock(¬ify_spinlock); 807 } 808 809 void unlock_notify(void) 810 { 811 spin_unlock(¬ify_spinlock); 812 } 813 814 __initcall(create_proc_mconsole); 815 816 #define NOTIFY "notify:" 817 818 static int mconsole_setup(char *str) 819 { 820 if (!strncmp(str, NOTIFY, strlen(NOTIFY))) { 821 str += strlen(NOTIFY); 822 notify_socket = str; 823 } 824 else printk(KERN_ERR "mconsole_setup : Unknown option - '%s'\n", str); 825 return 1; 826 } 827 828 __setup("mconsole=", mconsole_setup); 829 830 __uml_help(mconsole_setup, 831 "mconsole=notify:<socket>\n" 832 " Requests that the mconsole driver send a message to the named Unix\n" 833 " socket containing the name of the mconsole socket. This also serves\n" 834 " to notify outside processes when UML has booted far enough to respond\n" 835 " to mconsole requests.\n\n" 836 ); 837 838 static int notify_panic(struct notifier_block *self, unsigned long unused1, 839 void *ptr) 840 { 841 char *message = ptr; 842 843 if (notify_socket == NULL) 844 return 0; 845 846 mconsole_notify(notify_socket, MCONSOLE_PANIC, message, 847 strlen(message) + 1); 848 return 0; 849 } 850 851 static struct notifier_block panic_exit_notifier = { 852 .notifier_call = notify_panic, 853 .next = NULL, 854 .priority = 1 855 }; 856 857 static int add_notifier(void) 858 { 859 atomic_notifier_chain_register(&panic_notifier_list, 860 &panic_exit_notifier); 861 return 0; 862 } 863 864 __initcall(add_notifier); 865 866 char *mconsole_notify_socket(void) 867 { 868 return notify_socket; 869 } 870 871 EXPORT_SYMBOL(mconsole_notify_socket); 872