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 block_signals(); 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 unblock_signals(); 251 } 252 253 static DEFINE_SPINLOCK(mc_devices_lock); 254 static LIST_HEAD(mconsole_devices); 255 256 void mconsole_register_dev(struct mc_device *new) 257 { 258 spin_lock(&mc_devices_lock); 259 BUG_ON(!list_empty(&new->list)); 260 list_add(&new->list, &mconsole_devices); 261 spin_unlock(&mc_devices_lock); 262 } 263 264 static struct mc_device *mconsole_find_dev(char *name) 265 { 266 struct list_head *ele; 267 struct mc_device *dev; 268 269 list_for_each(ele, &mconsole_devices) { 270 dev = list_entry(ele, struct mc_device, list); 271 if (!strncmp(name, dev->name, strlen(dev->name))) 272 return dev; 273 } 274 return NULL; 275 } 276 277 #define UNPLUGGED_PER_PAGE \ 278 ((PAGE_SIZE - sizeof(struct list_head)) / sizeof(unsigned long)) 279 280 struct unplugged_pages { 281 struct list_head list; 282 void *pages[UNPLUGGED_PER_PAGE]; 283 }; 284 285 static DEFINE_MUTEX(plug_mem_mutex); 286 static unsigned long long unplugged_pages_count; 287 static LIST_HEAD(unplugged_pages); 288 static int unplug_index = UNPLUGGED_PER_PAGE; 289 290 static int mem_config(char *str, char **error_out) 291 { 292 unsigned long long diff; 293 int err = -EINVAL, i, add; 294 char *ret; 295 296 if (str[0] != '=') { 297 *error_out = "Expected '=' after 'mem'"; 298 goto out; 299 } 300 301 str++; 302 if (str[0] == '-') 303 add = 0; 304 else if (str[0] == '+') { 305 add = 1; 306 } 307 else { 308 *error_out = "Expected increment to start with '-' or '+'"; 309 goto out; 310 } 311 312 str++; 313 diff = memparse(str, &ret); 314 if (*ret != '\0') { 315 *error_out = "Failed to parse memory increment"; 316 goto out; 317 } 318 319 diff /= PAGE_SIZE; 320 321 mutex_lock(&plug_mem_mutex); 322 for (i = 0; i < diff; i++) { 323 struct unplugged_pages *unplugged; 324 void *addr; 325 326 if (add) { 327 if (list_empty(&unplugged_pages)) 328 break; 329 330 unplugged = list_entry(unplugged_pages.next, 331 struct unplugged_pages, list); 332 if (unplug_index > 0) 333 addr = unplugged->pages[--unplug_index]; 334 else { 335 list_del(&unplugged->list); 336 addr = unplugged; 337 unplug_index = UNPLUGGED_PER_PAGE; 338 } 339 340 free_page((unsigned long) addr); 341 unplugged_pages_count--; 342 } 343 else { 344 struct page *page; 345 346 page = alloc_page(GFP_ATOMIC); 347 if (page == NULL) 348 break; 349 350 unplugged = page_address(page); 351 if (unplug_index == UNPLUGGED_PER_PAGE) { 352 list_add(&unplugged->list, &unplugged_pages); 353 unplug_index = 0; 354 } 355 else { 356 struct list_head *entry = unplugged_pages.next; 357 addr = unplugged; 358 359 unplugged = list_entry(entry, 360 struct unplugged_pages, 361 list); 362 err = os_drop_memory(addr, PAGE_SIZE); 363 if (err) { 364 printk(KERN_ERR "Failed to release " 365 "memory - errno = %d\n", err); 366 *error_out = "Failed to release memory"; 367 goto out_unlock; 368 } 369 unplugged->pages[unplug_index++] = addr; 370 } 371 372 unplugged_pages_count++; 373 } 374 } 375 376 err = 0; 377 out_unlock: 378 mutex_unlock(&plug_mem_mutex); 379 out: 380 return err; 381 } 382 383 static int mem_get_config(char *name, char *str, int size, char **error_out) 384 { 385 char buf[sizeof("18446744073709551615")]; 386 int len = 0; 387 388 sprintf(buf, "%ld", uml_physmem); 389 CONFIG_CHUNK(str, size, len, buf, 1); 390 391 return len; 392 } 393 394 static int mem_id(char **str, int *start_out, int *end_out) 395 { 396 *start_out = 0; 397 *end_out = 0; 398 399 return 0; 400 } 401 402 static int mem_remove(int n, char **error_out) 403 { 404 *error_out = "Memory doesn't support the remove operation"; 405 return -EBUSY; 406 } 407 408 static struct mc_device mem_mc = { 409 .list = LIST_HEAD_INIT(mem_mc.list), 410 .name = "mem", 411 .config = mem_config, 412 .get_config = mem_get_config, 413 .id = mem_id, 414 .remove = mem_remove, 415 }; 416 417 static int __init mem_mc_init(void) 418 { 419 if (can_drop_memory()) 420 mconsole_register_dev(&mem_mc); 421 else printk(KERN_ERR "Can't release memory to the host - memory " 422 "hotplug won't be supported\n"); 423 return 0; 424 } 425 426 __initcall(mem_mc_init); 427 428 #define CONFIG_BUF_SIZE 64 429 430 static void mconsole_get_config(int (*get_config)(char *, char *, int, 431 char **), 432 struct mc_request *req, char *name) 433 { 434 char default_buf[CONFIG_BUF_SIZE], *error, *buf; 435 int n, size; 436 437 if (get_config == NULL) { 438 mconsole_reply(req, "No get_config routine defined", 1, 0); 439 return; 440 } 441 442 error = NULL; 443 size = ARRAY_SIZE(default_buf); 444 buf = default_buf; 445 446 while (1) { 447 n = (*get_config)(name, buf, size, &error); 448 if (error != NULL) { 449 mconsole_reply(req, error, 1, 0); 450 goto out; 451 } 452 453 if (n <= size) { 454 mconsole_reply(req, buf, 0, 0); 455 goto out; 456 } 457 458 if (buf != default_buf) 459 kfree(buf); 460 461 size = n; 462 buf = kmalloc(size, GFP_KERNEL); 463 if (buf == NULL) { 464 mconsole_reply(req, "Failed to allocate buffer", 1, 0); 465 return; 466 } 467 } 468 out: 469 if (buf != default_buf) 470 kfree(buf); 471 } 472 473 void mconsole_config(struct mc_request *req) 474 { 475 struct mc_device *dev; 476 char *ptr = req->request.data, *name, *error_string = ""; 477 int err; 478 479 ptr += strlen("config"); 480 ptr = skip_spaces(ptr); 481 dev = mconsole_find_dev(ptr); 482 if (dev == NULL) { 483 mconsole_reply(req, "Bad configuration option", 1, 0); 484 return; 485 } 486 487 name = &ptr[strlen(dev->name)]; 488 ptr = name; 489 while ((*ptr != '=') && (*ptr != '\0')) 490 ptr++; 491 492 if (*ptr == '=') { 493 err = (*dev->config)(name, &error_string); 494 mconsole_reply(req, error_string, err, 0); 495 } 496 else mconsole_get_config(dev->get_config, req, name); 497 } 498 499 void mconsole_remove(struct mc_request *req) 500 { 501 struct mc_device *dev; 502 char *ptr = req->request.data, *err_msg = ""; 503 char error[256]; 504 int err, start, end, n; 505 506 ptr += strlen("remove"); 507 ptr = skip_spaces(ptr); 508 dev = mconsole_find_dev(ptr); 509 if (dev == NULL) { 510 mconsole_reply(req, "Bad remove option", 1, 0); 511 return; 512 } 513 514 ptr = &ptr[strlen(dev->name)]; 515 516 err = 1; 517 n = (*dev->id)(&ptr, &start, &end); 518 if (n < 0) { 519 err_msg = "Couldn't parse device number"; 520 goto out; 521 } 522 else if ((n < start) || (n > end)) { 523 sprintf(error, "Invalid device number - must be between " 524 "%d and %d", start, end); 525 err_msg = error; 526 goto out; 527 } 528 529 err_msg = NULL; 530 err = (*dev->remove)(n, &err_msg); 531 switch(err) { 532 case 0: 533 err_msg = ""; 534 break; 535 case -ENODEV: 536 if (err_msg == NULL) 537 err_msg = "Device doesn't exist"; 538 break; 539 case -EBUSY: 540 if (err_msg == NULL) 541 err_msg = "Device is currently open"; 542 break; 543 default: 544 break; 545 } 546 out: 547 mconsole_reply(req, err_msg, err, 0); 548 } 549 550 struct mconsole_output { 551 struct list_head list; 552 struct mc_request *req; 553 }; 554 555 static DEFINE_SPINLOCK(client_lock); 556 static LIST_HEAD(clients); 557 static char console_buf[MCONSOLE_MAX_DATA]; 558 559 static void console_write(struct console *console, const char *string, 560 unsigned int len) 561 { 562 struct list_head *ele; 563 int n; 564 565 if (list_empty(&clients)) 566 return; 567 568 while (len > 0) { 569 n = min((size_t) len, ARRAY_SIZE(console_buf)); 570 strncpy(console_buf, string, n); 571 string += n; 572 len -= n; 573 574 list_for_each(ele, &clients) { 575 struct mconsole_output *entry; 576 577 entry = list_entry(ele, struct mconsole_output, list); 578 mconsole_reply_len(entry->req, console_buf, n, 0, 1); 579 } 580 } 581 } 582 583 static struct console mc_console = { .name = "mc", 584 .write = console_write, 585 .flags = CON_ENABLED, 586 .index = -1 }; 587 588 static int mc_add_console(void) 589 { 590 register_console(&mc_console); 591 return 0; 592 } 593 594 late_initcall(mc_add_console); 595 596 static void with_console(struct mc_request *req, void (*proc)(void *), 597 void *arg) 598 { 599 struct mconsole_output entry; 600 unsigned long flags; 601 602 entry.req = req; 603 spin_lock_irqsave(&client_lock, flags); 604 list_add(&entry.list, &clients); 605 spin_unlock_irqrestore(&client_lock, flags); 606 607 (*proc)(arg); 608 609 mconsole_reply_len(req, "", 0, 0, 0); 610 611 spin_lock_irqsave(&client_lock, flags); 612 list_del(&entry.list); 613 spin_unlock_irqrestore(&client_lock, flags); 614 } 615 616 #ifdef CONFIG_MAGIC_SYSRQ 617 618 #include <linux/sysrq.h> 619 620 static void sysrq_proc(void *arg) 621 { 622 char *op = arg; 623 handle_sysrq(*op); 624 } 625 626 void mconsole_sysrq(struct mc_request *req) 627 { 628 char *ptr = req->request.data; 629 630 ptr += strlen("sysrq"); 631 ptr = skip_spaces(ptr); 632 633 /* 634 * With 'b', the system will shut down without a chance to reply, 635 * so in this case, we reply first. 636 */ 637 if (*ptr == 'b') 638 mconsole_reply(req, "", 0, 0); 639 640 with_console(req, sysrq_proc, ptr); 641 } 642 #else 643 void mconsole_sysrq(struct mc_request *req) 644 { 645 mconsole_reply(req, "Sysrq not compiled in", 1, 0); 646 } 647 #endif 648 649 static void stack_proc(void *arg) 650 { 651 struct task_struct *task = arg; 652 653 show_stack(task, NULL, KERN_INFO); 654 } 655 656 /* 657 * Mconsole stack trace 658 * Added by Allan Graves, Jeff Dike 659 * Dumps a stacks registers to the linux console. 660 * Usage stack <pid>. 661 */ 662 void mconsole_stack(struct mc_request *req) 663 { 664 char *ptr = req->request.data; 665 int pid_requested= -1; 666 struct task_struct *to = NULL; 667 668 /* 669 * Would be nice: 670 * 1) Send showregs output to mconsole. 671 * 2) Add a way to stack dump all pids. 672 */ 673 674 ptr += strlen("stack"); 675 ptr = skip_spaces(ptr); 676 677 /* 678 * Should really check for multiple pids or reject bad args here 679 */ 680 /* What do the arguments in mconsole_reply mean? */ 681 if (sscanf(ptr, "%d", &pid_requested) == 0) { 682 mconsole_reply(req, "Please specify a pid", 1, 0); 683 return; 684 } 685 686 to = find_task_by_pid_ns(pid_requested, &init_pid_ns); 687 if ((to == NULL) || (pid_requested == 0)) { 688 mconsole_reply(req, "Couldn't find that pid", 1, 0); 689 return; 690 } 691 with_console(req, stack_proc, to); 692 } 693 694 static int __init mount_proc(void) 695 { 696 struct file_system_type *proc_fs_type; 697 struct vfsmount *mnt; 698 699 proc_fs_type = get_fs_type("proc"); 700 if (!proc_fs_type) 701 return -ENODEV; 702 703 mnt = kern_mount(proc_fs_type); 704 put_filesystem(proc_fs_type); 705 if (IS_ERR(mnt)) 706 return PTR_ERR(mnt); 707 708 proc_mnt = mnt; 709 return 0; 710 } 711 712 /* 713 * Changed by mconsole_setup, which is __setup, and called before SMP is 714 * active. 715 */ 716 static char *notify_socket = NULL; 717 718 static int __init mconsole_init(void) 719 { 720 /* long to avoid size mismatch warnings from gcc */ 721 long sock; 722 int err; 723 char file[UNIX_PATH_MAX]; 724 725 mount_proc(); 726 727 if (umid_file_name("mconsole", file, sizeof(file))) 728 return -1; 729 snprintf(mconsole_socket_name, sizeof(file), "%s", file); 730 731 sock = os_create_unix_socket(file, sizeof(file), 1); 732 if (sock < 0) { 733 printk(KERN_ERR "Failed to initialize management console\n"); 734 return 1; 735 } 736 if (os_set_fd_block(sock, 0)) 737 goto out; 738 739 register_reboot_notifier(&reboot_notifier); 740 741 err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt, 742 IRQF_SHARED, "mconsole", (void *)sock); 743 if (err < 0) { 744 printk(KERN_ERR "Failed to get IRQ for management console\n"); 745 goto out; 746 } 747 748 if (notify_socket != NULL) { 749 notify_socket = kstrdup(notify_socket, GFP_KERNEL); 750 if (notify_socket != NULL) 751 mconsole_notify(notify_socket, MCONSOLE_SOCKET, 752 mconsole_socket_name, 753 strlen(mconsole_socket_name) + 1); 754 else printk(KERN_ERR "mconsole_setup failed to strdup " 755 "string\n"); 756 } 757 758 printk(KERN_INFO "mconsole (version %d) initialized on %s\n", 759 MCONSOLE_VERSION, mconsole_socket_name); 760 return 0; 761 762 out: 763 os_close_file(sock); 764 return 1; 765 } 766 767 __initcall(mconsole_init); 768 769 static ssize_t mconsole_proc_write(struct file *file, 770 const char __user *buffer, size_t count, loff_t *pos) 771 { 772 char *buf; 773 774 buf = memdup_user_nul(buffer, count); 775 if (IS_ERR(buf)) 776 return PTR_ERR(buf); 777 778 mconsole_notify(notify_socket, MCONSOLE_USER_NOTIFY, buf, count); 779 kfree(buf); 780 return count; 781 } 782 783 static const struct proc_ops mconsole_proc_ops = { 784 .proc_write = mconsole_proc_write, 785 .proc_lseek = noop_llseek, 786 }; 787 788 static int create_proc_mconsole(void) 789 { 790 struct proc_dir_entry *ent; 791 792 if (notify_socket == NULL) 793 return 0; 794 795 ent = proc_create("mconsole", 0200, NULL, &mconsole_proc_ops); 796 if (ent == NULL) { 797 printk(KERN_INFO "create_proc_mconsole : proc_create failed\n"); 798 return 0; 799 } 800 return 0; 801 } 802 803 static DEFINE_SPINLOCK(notify_spinlock); 804 805 void lock_notify(void) 806 { 807 spin_lock(¬ify_spinlock); 808 } 809 810 void unlock_notify(void) 811 { 812 spin_unlock(¬ify_spinlock); 813 } 814 815 __initcall(create_proc_mconsole); 816 817 #define NOTIFY "notify:" 818 819 static int mconsole_setup(char *str) 820 { 821 if (!strncmp(str, NOTIFY, strlen(NOTIFY))) { 822 str += strlen(NOTIFY); 823 notify_socket = str; 824 } 825 else printk(KERN_ERR "mconsole_setup : Unknown option - '%s'\n", str); 826 return 1; 827 } 828 829 __setup("mconsole=", mconsole_setup); 830 831 __uml_help(mconsole_setup, 832 "mconsole=notify:<socket>\n" 833 " Requests that the mconsole driver send a message to the named Unix\n" 834 " socket containing the name of the mconsole socket. This also serves\n" 835 " to notify outside processes when UML has booted far enough to respond\n" 836 " to mconsole requests.\n\n" 837 ); 838 839 static int notify_panic(struct notifier_block *self, unsigned long unused1, 840 void *ptr) 841 { 842 char *message = ptr; 843 844 if (notify_socket == NULL) 845 return 0; 846 847 mconsole_notify(notify_socket, MCONSOLE_PANIC, message, 848 strlen(message) + 1); 849 return NOTIFY_DONE; 850 } 851 852 static struct notifier_block panic_exit_notifier = { 853 .notifier_call = notify_panic, 854 .priority = INT_MAX, /* run as soon as possible */ 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