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
40static struct vfsmount *proc_mnt = NULL;
41
42static int do_unlink_socket(struct notifier_block *notifier,
43 unsigned long what, void *data)
44{
45 return mconsole_unlink_socket();
46}
47
48
49static 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
59static LIST_HEAD(mc_requests);
60
61static void mc_work_proc(struct work_struct *unused)
62{
63 struct mconsole_entry *req;
64 unsigned long flags;
65
66 while (!list_empty(head: &mc_requests)) {
67 local_irq_save(flags);
68 req = list_entry(mc_requests.next, struct mconsole_entry, list);
69 list_del(entry: &req->list);
70 local_irq_restore(flags);
71 req->request.cmd->handler(&req->request);
72 kfree(objp: req);
73 }
74}
75
76static DECLARE_WORK(mconsole_work, mc_work_proc);
77
78static 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: &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: &req, str: "Out of memory", err: 1, more: 0);
93 else {
94 new->request = req;
95 new->request.regs = get_irq_regs()->regs;
96 list_add(new: &new->list, head: &mc_requests);
97 }
98 }
99 }
100 if (!list_empty(head: &mc_requests))
101 schedule_work(work: &mconsole_work);
102 return IRQ_HANDLED;
103}
104
105void mconsole_version(struct mc_request *req)
106{
107 char version[256];
108
109 sprintf(buf: version, fmt: "%s %s %s %s %s", utsname()->sysname,
110 utsname()->nodename, utsname()->release, utsname()->version,
111 utsname()->machine);
112 mconsole_reply(req, str: version, err: 0, more: 0);
113}
114
115void 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, str: "", err: 0, more: 0);
125}
126
127void 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, str: "Proc not available", err: 1, more: 0);
142 goto out;
143 }
144 file = file_open_root_mnt(mnt, name: ptr, O_RDONLY, mode: 0);
145 if (IS_ERR(ptr: file)) {
146 mconsole_reply(req, str: "Failed to open file", err: 1, more: 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, str: "Failed to allocate buffer", err: 1, more: 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, str: "Read of file failed", err: 1, more: 0);
161 goto out_free;
162 }
163 /* Begin the file content on his own line. */
164 if (first_chunk) {
165 mconsole_reply(req, str: "\n", err: 0, more: 1);
166 first_chunk = 0;
167 }
168 buf[len] = '\0';
169 mconsole_reply(req, str: buf, err: 0, more: (len > 0));
170 } while (len > 0);
171 out_free:
172 kfree(objp: 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
197void mconsole_help(struct mc_request *req)
198{
199 mconsole_reply(req, UML_MCONSOLE_HELPTEXT, err: 0, more: 0);
200}
201
202void mconsole_halt(struct mc_request *req)
203{
204 mconsole_reply(req, str: "", err: 0, more: 0);
205 machine_halt();
206}
207
208void mconsole_reboot(struct mc_request *req)
209{
210 mconsole_reply(req, str: "", err: 0, more: 0);
211 machine_restart(NULL);
212}
213
214void mconsole_cad(struct mc_request *req)
215{
216 mconsole_reply(req, str: "", err: 0, more: 0);
217 ctrl_alt_del();
218}
219
220void mconsole_go(struct mc_request *req)
221{
222 mconsole_reply(req, str: "Not stopped", err: 1, more: 0);
223}
224
225void mconsole_stop(struct mc_request *req)
226{
227 block_signals();
228 os_set_fd_block(req->originating_fd, 1);
229 mconsole_reply(req, str: "stopped", err: 0, more: 0);
230 for (;;) {
231 if (!mconsole_get_request(fd: 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, str: "Already stopped", err: 1, more: 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, str: "", err: 0, more: 0);
250 unblock_signals();
251}
252
253static DEFINE_SPINLOCK(mc_devices_lock);
254static LIST_HEAD(mconsole_devices);
255
256void mconsole_register_dev(struct mc_device *new)
257{
258 spin_lock(lock: &mc_devices_lock);
259 BUG_ON(!list_empty(&new->list));
260 list_add(new: &new->list, head: &mconsole_devices);
261 spin_unlock(lock: &mc_devices_lock);
262}
263
264static 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
280struct unplugged_pages {
281 struct list_head list;
282 void *pages[UNPLUGGED_PER_PAGE];
283};
284
285static DEFINE_MUTEX(plug_mem_mutex);
286static unsigned long long unplugged_pages_count;
287static LIST_HEAD(unplugged_pages);
288static int unplug_index = UNPLUGGED_PER_PAGE;
289
290static 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(ptr: str, retptr: &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(head: &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(entry: &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(new: &unplugged->list, head: &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;
377out_unlock:
378 mutex_unlock(lock: &plug_mem_mutex);
379out:
380 return err;
381}
382
383static 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, fmt: "%ld", uml_physmem);
389 CONFIG_CHUNK(str, size, len, buf, 1);
390
391 return len;
392}
393
394static 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
402static int mem_remove(int n, char **error_out)
403{
404 *error_out = "Memory doesn't support the remove operation";
405 return -EBUSY;
406}
407
408static 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
417static 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
430static 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, str: "No get_config routine defined", err: 1, more: 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, str: error, err: 1, more: 0);
450 goto out;
451 }
452
453 if (n <= size) {
454 mconsole_reply(req, str: buf, err: 0, more: 0);
455 goto out;
456 }
457
458 if (buf != default_buf)
459 kfree(objp: buf);
460
461 size = n;
462 buf = kmalloc(size, GFP_KERNEL);
463 if (buf == NULL) {
464 mconsole_reply(req, str: "Failed to allocate buffer", err: 1, more: 0);
465 return;
466 }
467 }
468 out:
469 if (buf != default_buf)
470 kfree(objp: buf);
471}
472
473void 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(name: ptr);
482 if (dev == NULL) {
483 mconsole_reply(req, str: "Bad configuration option", err: 1, more: 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, str: error_string, err, more: 0);
495 }
496 else mconsole_get_config(get_config: dev->get_config, req, name);
497}
498
499void 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(name: ptr);
509 if (dev == NULL) {
510 mconsole_reply(req, str: "Bad remove option", err: 1, more: 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(buf: error, fmt: "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 }
546out:
547 mconsole_reply(req, str: err_msg, err, more: 0);
548}
549
550struct mconsole_output {
551 struct list_head list;
552 struct mc_request *req;
553};
554
555static DEFINE_SPINLOCK(client_lock);
556static LIST_HEAD(clients);
557static char console_buf[MCONSOLE_MAX_DATA] __nonstring;
558
559static 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(head: &clients))
566 return;
567
568 while (len > 0) {
569 n = min((size_t) len, ARRAY_SIZE(console_buf));
570 memcpy(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(req: entry->req, reply: console_buf, len: n, err: 0, more: 1);
579 }
580 }
581}
582
583static struct console mc_console = { .name = "mc",
584 .write = console_write,
585 .flags = CON_ENABLED,
586 .index = -1 };
587
588static int mc_add_console(void)
589{
590 register_console(&mc_console);
591 return 0;
592}
593
594late_initcall(mc_add_console);
595
596static 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(new: &entry.list, head: &clients);
605 spin_unlock_irqrestore(lock: &client_lock, flags);
606
607 (*proc)(arg);
608
609 mconsole_reply_len(req, reply: "", len: 0, err: 0, more: 0);
610
611 spin_lock_irqsave(&client_lock, flags);
612 list_del(entry: &entry.list);
613 spin_unlock_irqrestore(lock: &client_lock, flags);
614}
615
616#ifdef CONFIG_MAGIC_SYSRQ
617
618#include <linux/sysrq.h>
619
620static void sysrq_proc(void *arg)
621{
622 char *op = arg;
623 handle_sysrq(key: *op);
624}
625
626void 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, str: "", err: 0, more: 0);
639
640 with_console(req, proc: sysrq_proc, arg: ptr);
641}
642#else
643void mconsole_sysrq(struct mc_request *req)
644{
645 mconsole_reply(req, "Sysrq not compiled in", 1, 0);
646}
647#endif
648
649static 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 */
662void 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, str: "Please specify a pid", err: 1, more: 0);
683 return;
684 }
685
686 to = find_task_by_pid_ns(nr: pid_requested, ns: &init_pid_ns);
687 if ((to == NULL) || (pid_requested == 0)) {
688 mconsole_reply(req, str: "Couldn't find that pid", err: 1, more: 0);
689 return;
690 }
691 with_console(req, proc: stack_proc, arg: to);
692}
693
694static 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(name: "proc");
700 if (!proc_fs_type)
701 return -ENODEV;
702
703 mnt = kern_mount(proc_fs_type);
704 put_filesystem(fs: proc_fs_type);
705 if (IS_ERR(ptr: mnt))
706 return PTR_ERR(ptr: 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 */
716static char *notify_socket = NULL;
717
718static 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(buf: mconsole_socket_name, size: sizeof(file), fmt: "%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(s: notify_socket, GFP_KERNEL);
750 if (notify_socket != NULL)
751 mconsole_notify(sock_name: notify_socket, type: MCONSOLE_SOCKET,
752 data: 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
769static 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(ptr: buf))
776 return PTR_ERR(ptr: buf);
777
778 mconsole_notify(sock_name: notify_socket, type: MCONSOLE_USER_NOTIFY, data: buf, len: count);
779 kfree(objp: buf);
780 return count;
781}
782
783static const struct proc_ops mconsole_proc_ops = {
784 .proc_write = mconsole_proc_write,
785 .proc_lseek = noop_llseek,
786};
787
788static 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(name: "mconsole", mode: 0200, NULL, proc_ops: &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
803static DEFINE_SPINLOCK(notify_spinlock);
804
805void lock_notify(void)
806{
807 spin_lock(lock: &notify_spinlock);
808}
809
810void unlock_notify(void)
811{
812 spin_unlock(lock: &notify_spinlock);
813}
814
815__initcall(create_proc_mconsole);
816
817#define NOTIFY "notify:"
818
819static 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
839static 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(sock_name: notify_socket, type: MCONSOLE_PANIC, data: message,
848 strlen(message) + 1);
849 return NOTIFY_DONE;
850}
851
852static struct notifier_block panic_exit_notifier = {
853 .notifier_call = notify_panic,
854 .priority = INT_MAX, /* run as soon as possible */
855};
856
857static int add_notifier(void)
858{
859 atomic_notifier_chain_register(nh: &panic_notifier_list,
860 nb: &panic_exit_notifier);
861 return 0;
862}
863
864__initcall(add_notifier);
865
866char *mconsole_notify_socket(void)
867{
868 return notify_socket;
869}
870
871EXPORT_SYMBOL(mconsole_notify_socket);
872

source code of linux/arch/um/drivers/mconsole_kern.c