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