xref: /openbmc/linux/arch/um/drivers/mconsole_kern.c (revision 22246614)
1 /*
2  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
3  * Copyright (C) 2001 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4  * Licensed under the GPL
5  */
6 
7 #include <linux/console.h>
8 #include <linux/ctype.h>
9 #include <linux/interrupt.h>
10 #include <linux/list.h>
11 #include <linux/mm.h>
12 #include <linux/module.h>
13 #include <linux/notifier.h>
14 #include <linux/reboot.h>
15 #include <linux/proc_fs.h>
16 #include <linux/slab.h>
17 #include <linux/syscalls.h>
18 #include <linux/utsname.h>
19 #include <linux/workqueue.h>
20 #include <linux/mutex.h>
21 #include <asm/uaccess.h>
22 
23 #include "init.h"
24 #include "irq_kern.h"
25 #include "irq_user.h"
26 #include "kern_util.h"
27 #include "mconsole.h"
28 #include "mconsole_kern.h"
29 #include "os.h"
30 
31 static int do_unlink_socket(struct notifier_block *notifier,
32 			    unsigned long what, void *data)
33 {
34 	return mconsole_unlink_socket();
35 }
36 
37 
38 static struct notifier_block reboot_notifier = {
39 	.notifier_call		= do_unlink_socket,
40 	.priority		= 0,
41 };
42 
43 /* Safe without explicit locking for now.  Tasklets provide their own
44  * locking, and the interrupt handler is safe because it can't interrupt
45  * itself and it can only happen on CPU 0.
46  */
47 
48 static LIST_HEAD(mc_requests);
49 
50 static void mc_work_proc(struct work_struct *unused)
51 {
52 	struct mconsole_entry *req;
53 	unsigned long flags;
54 
55 	while (!list_empty(&mc_requests)) {
56 		local_irq_save(flags);
57 		req = list_entry(mc_requests.next, struct mconsole_entry, list);
58 		list_del(&req->list);
59 		local_irq_restore(flags);
60 		req->request.cmd->handler(&req->request);
61 		kfree(req);
62 	}
63 }
64 
65 static DECLARE_WORK(mconsole_work, mc_work_proc);
66 
67 static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
68 {
69 	/* long to avoid size mismatch warnings from gcc */
70 	long fd;
71 	struct mconsole_entry *new;
72 	static struct mc_request req;	/* that's OK */
73 
74 	fd = (long) dev_id;
75 	while (mconsole_get_request(fd, &req)) {
76 		if (req.cmd->context == MCONSOLE_INTR)
77 			(*req.cmd->handler)(&req);
78 		else {
79 			new = kmalloc(sizeof(*new), GFP_NOWAIT);
80 			if (new == NULL)
81 				mconsole_reply(&req, "Out of memory", 1, 0);
82 			else {
83 				new->request = req;
84 				new->request.regs = get_irq_regs()->regs;
85 				list_add(&new->list, &mc_requests);
86 			}
87 		}
88 	}
89 	if (!list_empty(&mc_requests))
90 		schedule_work(&mconsole_work);
91 	reactivate_fd(fd, MCONSOLE_IRQ);
92 	return IRQ_HANDLED;
93 }
94 
95 void mconsole_version(struct mc_request *req)
96 {
97 	char version[256];
98 
99 	sprintf(version, "%s %s %s %s %s", utsname()->sysname,
100 		utsname()->nodename, utsname()->release, utsname()->version,
101 		utsname()->machine);
102 	mconsole_reply(req, version, 0, 0);
103 }
104 
105 void mconsole_log(struct mc_request *req)
106 {
107 	int len;
108 	char *ptr = req->request.data;
109 
110 	ptr += strlen("log ");
111 
112 	len = req->len - (ptr - req->request.data);
113 	printk(KERN_WARNING "%.*s", len, ptr);
114 	mconsole_reply(req, "", 0, 0);
115 }
116 
117 /* This is a more convoluted version of mconsole_proc, which has some stability
118  * problems; however, we need it fixed, because it is expected that UML users
119  * mount HPPFS instead of procfs on /proc. And we want mconsole_proc to still
120  * show the real procfs content, not the ones from hppfs.*/
121 #if 0
122 void mconsole_proc(struct mc_request *req)
123 {
124 	struct nameidata nd;
125 	struct file_system_type *proc;
126 	struct super_block *super;
127 	struct file *file;
128 	int n, err;
129 	char *ptr = req->request.data, *buf;
130 
131 	ptr += strlen("proc");
132 	while (isspace(*ptr)) ptr++;
133 
134 	proc = get_fs_type("proc");
135 	if (proc == NULL) {
136 		mconsole_reply(req, "procfs not registered", 1, 0);
137 		goto out;
138 	}
139 
140 	super = (*proc->get_sb)(proc, 0, NULL, NULL);
141 	put_filesystem(proc);
142 	if (super == NULL) {
143 		mconsole_reply(req, "Failed to get procfs superblock", 1, 0);
144 		goto out;
145 	}
146 	up_write(&super->s_umount);
147 
148 	nd.path.dentry = super->s_root;
149 	nd.path.mnt = NULL;
150 	nd.flags = O_RDONLY + 1;
151 	nd.last_type = LAST_ROOT;
152 
153 	/* START: it was experienced that the stability problems are closed
154 	 * if commenting out these two calls + the below read cycle. To
155 	 * make UML crash again, it was enough to readd either one.*/
156 	err = link_path_walk(ptr, &nd);
157 	if (err) {
158 		mconsole_reply(req, "Failed to look up file", 1, 0);
159 		goto out_kill;
160 	}
161 
162 	file = dentry_open(nd.path.dentry, nd.path.mnt, O_RDONLY);
163 	if (IS_ERR(file)) {
164 		mconsole_reply(req, "Failed to open file", 1, 0);
165 		goto out_kill;
166 	}
167 	/*END*/
168 
169 	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
170 	if (buf == NULL) {
171 		mconsole_reply(req, "Failed to allocate buffer", 1, 0);
172 		goto out_fput;
173 	}
174 
175 	if ((file->f_op != NULL) && (file->f_op->read != NULL)) {
176 		do {
177 			n = (*file->f_op->read)(file, buf, PAGE_SIZE - 1,
178 						&file->f_pos);
179 			if (n >= 0) {
180 				buf[n] = '\0';
181 				mconsole_reply(req, buf, 0, (n > 0));
182 			}
183 			else {
184 				mconsole_reply(req, "Read of file failed",
185 					       1, 0);
186 				goto out_free;
187 			}
188 		} while (n > 0);
189 	}
190 	else mconsole_reply(req, "", 0, 0);
191 
192  out_free:
193 	kfree(buf);
194  out_fput:
195 	fput(file);
196  out_kill:
197 	deactivate_super(super);
198  out: ;
199 }
200 #endif
201 
202 void mconsole_proc(struct mc_request *req)
203 {
204 	char path[64];
205 	char *buf;
206 	int len;
207 	int fd;
208 	int first_chunk = 1;
209 	char *ptr = req->request.data;
210 
211 	ptr += strlen("proc");
212 	while (isspace(*ptr))
213 		ptr++;
214 	snprintf(path, sizeof(path), "/proc/%s", ptr);
215 
216 	fd = sys_open(path, 0, 0);
217 	if (fd < 0) {
218 		mconsole_reply(req, "Failed to open file", 1, 0);
219 		printk(KERN_ERR "open %s: %d\n",path,fd);
220 		goto out;
221 	}
222 
223 	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
224 	if (buf == NULL) {
225 		mconsole_reply(req, "Failed to allocate buffer", 1, 0);
226 		goto out_close;
227 	}
228 
229 	for (;;) {
230 		len = sys_read(fd, buf, PAGE_SIZE-1);
231 		if (len < 0) {
232 			mconsole_reply(req, "Read of file failed", 1, 0);
233 			goto out_free;
234 		}
235 		/* Begin the file content on his own line. */
236 		if (first_chunk) {
237 			mconsole_reply(req, "\n", 0, 1);
238 			first_chunk = 0;
239 		}
240 		if (len == PAGE_SIZE-1) {
241 			buf[len] = '\0';
242 			mconsole_reply(req, buf, 0, 1);
243 		} else {
244 			buf[len] = '\0';
245 			mconsole_reply(req, buf, 0, 0);
246 			break;
247 		}
248 	}
249 
250  out_free:
251 	kfree(buf);
252  out_close:
253 	sys_close(fd);
254  out:
255 	/* nothing */;
256 }
257 
258 #define UML_MCONSOLE_HELPTEXT \
259 "Commands: \n\
260     version - Get kernel version \n\
261     help - Print this message \n\
262     halt - Halt UML \n\
263     reboot - Reboot UML \n\
264     config <dev>=<config> - Add a new device to UML;  \n\
265 	same syntax as command line \n\
266     config <dev> - Query the configuration of a device \n\
267     remove <dev> - Remove a device from UML \n\
268     sysrq <letter> - Performs the SysRq action controlled by the letter \n\
269     cad - invoke the Ctrl-Alt-Del handler \n\
270     stop - pause the UML; it will do nothing until it receives a 'go' \n\
271     go - continue the UML after a 'stop' \n\
272     log <string> - make UML enter <string> into the kernel log\n\
273     proc <file> - returns the contents of the UML's /proc/<file>\n\
274     stack <pid> - returns the stack of the specified pid\n\
275 "
276 
277 void mconsole_help(struct mc_request *req)
278 {
279 	mconsole_reply(req, UML_MCONSOLE_HELPTEXT, 0, 0);
280 }
281 
282 void mconsole_halt(struct mc_request *req)
283 {
284 	mconsole_reply(req, "", 0, 0);
285 	machine_halt();
286 }
287 
288 void mconsole_reboot(struct mc_request *req)
289 {
290 	mconsole_reply(req, "", 0, 0);
291 	machine_restart(NULL);
292 }
293 
294 void mconsole_cad(struct mc_request *req)
295 {
296 	mconsole_reply(req, "", 0, 0);
297 	ctrl_alt_del();
298 }
299 
300 void mconsole_go(struct mc_request *req)
301 {
302 	mconsole_reply(req, "Not stopped", 1, 0);
303 }
304 
305 void mconsole_stop(struct mc_request *req)
306 {
307 	deactivate_fd(req->originating_fd, MCONSOLE_IRQ);
308 	os_set_fd_block(req->originating_fd, 1);
309 	mconsole_reply(req, "stopped", 0, 0);
310 	for (;;) {
311 		if (!mconsole_get_request(req->originating_fd, req))
312 			continue;
313 		if (req->cmd->handler == mconsole_go)
314 			break;
315 		if (req->cmd->handler == mconsole_stop) {
316 			mconsole_reply(req, "Already stopped", 1, 0);
317 			continue;
318 		}
319 		if (req->cmd->handler == mconsole_sysrq) {
320 			struct pt_regs *old_regs;
321 			old_regs = set_irq_regs((struct pt_regs *)&req->regs);
322 			mconsole_sysrq(req);
323 			set_irq_regs(old_regs);
324 			continue;
325 		}
326 		(*req->cmd->handler)(req);
327 	}
328 	os_set_fd_block(req->originating_fd, 0);
329 	reactivate_fd(req->originating_fd, MCONSOLE_IRQ);
330 	mconsole_reply(req, "", 0, 0);
331 }
332 
333 static DEFINE_SPINLOCK(mc_devices_lock);
334 static LIST_HEAD(mconsole_devices);
335 
336 void mconsole_register_dev(struct mc_device *new)
337 {
338 	spin_lock(&mc_devices_lock);
339 	BUG_ON(!list_empty(&new->list));
340 	list_add(&new->list, &mconsole_devices);
341 	spin_unlock(&mc_devices_lock);
342 }
343 
344 static struct mc_device *mconsole_find_dev(char *name)
345 {
346 	struct list_head *ele;
347 	struct mc_device *dev;
348 
349 	list_for_each(ele, &mconsole_devices) {
350 		dev = list_entry(ele, struct mc_device, list);
351 		if (!strncmp(name, dev->name, strlen(dev->name)))
352 			return dev;
353 	}
354 	return NULL;
355 }
356 
357 #define UNPLUGGED_PER_PAGE \
358 	((PAGE_SIZE - sizeof(struct list_head)) / sizeof(unsigned long))
359 
360 struct unplugged_pages {
361 	struct list_head list;
362 	void *pages[UNPLUGGED_PER_PAGE];
363 };
364 
365 static DEFINE_MUTEX(plug_mem_mutex);
366 static unsigned long long unplugged_pages_count = 0;
367 static LIST_HEAD(unplugged_pages);
368 static int unplug_index = UNPLUGGED_PER_PAGE;
369 
370 static int mem_config(char *str, char **error_out)
371 {
372 	unsigned long long diff;
373 	int err = -EINVAL, i, add;
374 	char *ret;
375 
376 	if (str[0] != '=') {
377 		*error_out = "Expected '=' after 'mem'";
378 		goto out;
379 	}
380 
381 	str++;
382 	if (str[0] == '-')
383 		add = 0;
384 	else if (str[0] == '+') {
385 		add = 1;
386 	}
387 	else {
388 		*error_out = "Expected increment to start with '-' or '+'";
389 		goto out;
390 	}
391 
392 	str++;
393 	diff = memparse(str, &ret);
394 	if (*ret != '\0') {
395 		*error_out = "Failed to parse memory increment";
396 		goto out;
397 	}
398 
399 	diff /= PAGE_SIZE;
400 
401 	mutex_lock(&plug_mem_mutex);
402 	for (i = 0; i < diff; i++) {
403 		struct unplugged_pages *unplugged;
404 		void *addr;
405 
406 		if (add) {
407 			if (list_empty(&unplugged_pages))
408 				break;
409 
410 			unplugged = list_entry(unplugged_pages.next,
411 					       struct unplugged_pages, list);
412 			if (unplug_index > 0)
413 				addr = unplugged->pages[--unplug_index];
414 			else {
415 				list_del(&unplugged->list);
416 				addr = unplugged;
417 				unplug_index = UNPLUGGED_PER_PAGE;
418 			}
419 
420 			free_page((unsigned long) addr);
421 			unplugged_pages_count--;
422 		}
423 		else {
424 			struct page *page;
425 
426 			page = alloc_page(GFP_ATOMIC);
427 			if (page == NULL)
428 				break;
429 
430 			unplugged = page_address(page);
431 			if (unplug_index == UNPLUGGED_PER_PAGE) {
432 				list_add(&unplugged->list, &unplugged_pages);
433 				unplug_index = 0;
434 			}
435 			else {
436 				struct list_head *entry = unplugged_pages.next;
437 				addr = unplugged;
438 
439 				unplugged = list_entry(entry,
440 						       struct unplugged_pages,
441 						       list);
442 				err = os_drop_memory(addr, PAGE_SIZE);
443 				if (err) {
444 					printk(KERN_ERR "Failed to release "
445 					       "memory - errno = %d\n", err);
446 					*error_out = "Failed to release memory";
447 					goto out_unlock;
448 				}
449 				unplugged->pages[unplug_index++] = addr;
450 			}
451 
452 			unplugged_pages_count++;
453 		}
454 	}
455 
456 	err = 0;
457 out_unlock:
458 	mutex_unlock(&plug_mem_mutex);
459 out:
460 	return err;
461 }
462 
463 static int mem_get_config(char *name, char *str, int size, char **error_out)
464 {
465 	char buf[sizeof("18446744073709551615")];
466 	int len = 0;
467 
468 	sprintf(buf, "%ld", uml_physmem);
469 	CONFIG_CHUNK(str, size, len, buf, 1);
470 
471 	return len;
472 }
473 
474 static int mem_id(char **str, int *start_out, int *end_out)
475 {
476 	*start_out = 0;
477 	*end_out = 0;
478 
479 	return 0;
480 }
481 
482 static int mem_remove(int n, char **error_out)
483 {
484 	*error_out = "Memory doesn't support the remove operation";
485 	return -EBUSY;
486 }
487 
488 static struct mc_device mem_mc = {
489 	.list		= LIST_HEAD_INIT(mem_mc.list),
490 	.name		= "mem",
491 	.config		= mem_config,
492 	.get_config	= mem_get_config,
493 	.id		= mem_id,
494 	.remove		= mem_remove,
495 };
496 
497 static int __init mem_mc_init(void)
498 {
499 	if (can_drop_memory())
500 		mconsole_register_dev(&mem_mc);
501 	else printk(KERN_ERR "Can't release memory to the host - memory "
502 		    "hotplug won't be supported\n");
503 	return 0;
504 }
505 
506 __initcall(mem_mc_init);
507 
508 #define CONFIG_BUF_SIZE 64
509 
510 static void mconsole_get_config(int (*get_config)(char *, char *, int,
511 						  char **),
512 				struct mc_request *req, char *name)
513 {
514 	char default_buf[CONFIG_BUF_SIZE], *error, *buf;
515 	int n, size;
516 
517 	if (get_config == NULL) {
518 		mconsole_reply(req, "No get_config routine defined", 1, 0);
519 		return;
520 	}
521 
522 	error = NULL;
523 	size = ARRAY_SIZE(default_buf);
524 	buf = default_buf;
525 
526 	while (1) {
527 		n = (*get_config)(name, buf, size, &error);
528 		if (error != NULL) {
529 			mconsole_reply(req, error, 1, 0);
530 			goto out;
531 		}
532 
533 		if (n <= size) {
534 			mconsole_reply(req, buf, 0, 0);
535 			goto out;
536 		}
537 
538 		if (buf != default_buf)
539 			kfree(buf);
540 
541 		size = n;
542 		buf = kmalloc(size, GFP_KERNEL);
543 		if (buf == NULL) {
544 			mconsole_reply(req, "Failed to allocate buffer", 1, 0);
545 			return;
546 		}
547 	}
548  out:
549 	if (buf != default_buf)
550 		kfree(buf);
551 }
552 
553 void mconsole_config(struct mc_request *req)
554 {
555 	struct mc_device *dev;
556 	char *ptr = req->request.data, *name, *error_string = "";
557 	int err;
558 
559 	ptr += strlen("config");
560 	while (isspace(*ptr))
561 		ptr++;
562 	dev = mconsole_find_dev(ptr);
563 	if (dev == NULL) {
564 		mconsole_reply(req, "Bad configuration option", 1, 0);
565 		return;
566 	}
567 
568 	name = &ptr[strlen(dev->name)];
569 	ptr = name;
570 	while ((*ptr != '=') && (*ptr != '\0'))
571 		ptr++;
572 
573 	if (*ptr == '=') {
574 		err = (*dev->config)(name, &error_string);
575 		mconsole_reply(req, error_string, err, 0);
576 	}
577 	else mconsole_get_config(dev->get_config, req, name);
578 }
579 
580 void mconsole_remove(struct mc_request *req)
581 {
582 	struct mc_device *dev;
583 	char *ptr = req->request.data, *err_msg = "";
584 	char error[256];
585 	int err, start, end, n;
586 
587 	ptr += strlen("remove");
588 	while (isspace(*ptr)) ptr++;
589 	dev = mconsole_find_dev(ptr);
590 	if (dev == NULL) {
591 		mconsole_reply(req, "Bad remove option", 1, 0);
592 		return;
593 	}
594 
595 	ptr = &ptr[strlen(dev->name)];
596 
597 	err = 1;
598 	n = (*dev->id)(&ptr, &start, &end);
599 	if (n < 0) {
600 		err_msg = "Couldn't parse device number";
601 		goto out;
602 	}
603 	else if ((n < start) || (n > end)) {
604 		sprintf(error, "Invalid device number - must be between "
605 			"%d and %d", start, end);
606 		err_msg = error;
607 		goto out;
608 	}
609 
610 	err_msg = NULL;
611 	err = (*dev->remove)(n, &err_msg);
612 	switch(err) {
613 	case 0:
614 		err_msg = "";
615 		break;
616 	case -ENODEV:
617 		if (err_msg == NULL)
618 			err_msg = "Device doesn't exist";
619 		break;
620 	case -EBUSY:
621 		if (err_msg == NULL)
622 			err_msg = "Device is currently open";
623 		break;
624 	default:
625 		break;
626 	}
627 out:
628 	mconsole_reply(req, err_msg, err, 0);
629 }
630 
631 struct mconsole_output {
632 	struct list_head list;
633 	struct mc_request *req;
634 };
635 
636 static DEFINE_SPINLOCK(client_lock);
637 static LIST_HEAD(clients);
638 static char console_buf[MCONSOLE_MAX_DATA];
639 
640 static void console_write(struct console *console, const char *string,
641 			  unsigned int len)
642 {
643 	struct list_head *ele;
644 	int n;
645 
646 	if (list_empty(&clients))
647 		return;
648 
649 	while (len > 0) {
650 		n = min((size_t) len, ARRAY_SIZE(console_buf));
651 		strncpy(console_buf, string, n);
652 		string += n;
653 		len -= n;
654 
655 		list_for_each(ele, &clients) {
656 			struct mconsole_output *entry;
657 
658 			entry = list_entry(ele, struct mconsole_output, list);
659 			mconsole_reply_len(entry->req, console_buf, n, 0, 1);
660 		}
661 	}
662 }
663 
664 static struct console mc_console = { .name	= "mc",
665 				     .write	= console_write,
666 				     .flags	= CON_ENABLED,
667 				     .index	= -1 };
668 
669 static int mc_add_console(void)
670 {
671 	register_console(&mc_console);
672 	return 0;
673 }
674 
675 late_initcall(mc_add_console);
676 
677 static void with_console(struct mc_request *req, void (*proc)(void *),
678 			 void *arg)
679 {
680 	struct mconsole_output entry;
681 	unsigned long flags;
682 
683 	entry.req = req;
684 	spin_lock_irqsave(&client_lock, flags);
685 	list_add(&entry.list, &clients);
686 	spin_unlock_irqrestore(&client_lock, flags);
687 
688 	(*proc)(arg);
689 
690 	mconsole_reply_len(req, "", 0, 0, 0);
691 
692 	spin_lock_irqsave(&client_lock, flags);
693 	list_del(&entry.list);
694 	spin_unlock_irqrestore(&client_lock, flags);
695 }
696 
697 #ifdef CONFIG_MAGIC_SYSRQ
698 
699 #include <linux/sysrq.h>
700 
701 static void sysrq_proc(void *arg)
702 {
703 	char *op = arg;
704 	handle_sysrq(*op, NULL);
705 }
706 
707 void mconsole_sysrq(struct mc_request *req)
708 {
709 	char *ptr = req->request.data;
710 
711 	ptr += strlen("sysrq");
712 	while (isspace(*ptr)) ptr++;
713 
714 	/*
715 	 * With 'b', the system will shut down without a chance to reply,
716 	 * so in this case, we reply first.
717 	 */
718 	if (*ptr == 'b')
719 		mconsole_reply(req, "", 0, 0);
720 
721 	with_console(req, sysrq_proc, ptr);
722 }
723 #else
724 void mconsole_sysrq(struct mc_request *req)
725 {
726 	mconsole_reply(req, "Sysrq not compiled in", 1, 0);
727 }
728 #endif
729 
730 static void stack_proc(void *arg)
731 {
732 	struct task_struct *from = current, *to = arg;
733 
734 	to->thread.saved_task = from;
735 	switch_to(from, to, from);
736 }
737 
738 /*
739  * Mconsole stack trace
740  *  Added by Allan Graves, Jeff Dike
741  *  Dumps a stacks registers to the linux console.
742  *  Usage stack <pid>.
743  */
744 void mconsole_stack(struct mc_request *req)
745 {
746 	char *ptr = req->request.data;
747 	int pid_requested= -1;
748 	struct task_struct *to = NULL;
749 
750 	/*
751 	 * Would be nice:
752 	 * 1) Send showregs output to mconsole.
753 	 * 2) Add a way to stack dump all pids.
754 	 */
755 
756 	ptr += strlen("stack");
757 	while (isspace(*ptr))
758 		ptr++;
759 
760 	/*
761 	 * Should really check for multiple pids or reject bad args here
762 	 */
763 	/* What do the arguments in mconsole_reply mean? */
764 	if (sscanf(ptr, "%d", &pid_requested) == 0) {
765 		mconsole_reply(req, "Please specify a pid", 1, 0);
766 		return;
767 	}
768 
769 	to = find_task_by_pid_ns(pid_requested, &init_pid_ns);
770 	if ((to == NULL) || (pid_requested == 0)) {
771 		mconsole_reply(req, "Couldn't find that pid", 1, 0);
772 		return;
773 	}
774 	with_console(req, stack_proc, to);
775 }
776 
777 /*
778  * Changed by mconsole_setup, which is __setup, and called before SMP is
779  * active.
780  */
781 static char *notify_socket = NULL;
782 
783 static int __init mconsole_init(void)
784 {
785 	/* long to avoid size mismatch warnings from gcc */
786 	long sock;
787 	int err;
788 	char file[256];
789 
790 	if (umid_file_name("mconsole", file, sizeof(file)))
791 		return -1;
792 	snprintf(mconsole_socket_name, sizeof(file), "%s", file);
793 
794 	sock = os_create_unix_socket(file, sizeof(file), 1);
795 	if (sock < 0) {
796 		printk(KERN_ERR "Failed to initialize management console\n");
797 		return 1;
798 	}
799 	if (os_set_fd_block(sock, 0))
800 		goto out;
801 
802 	register_reboot_notifier(&reboot_notifier);
803 
804 	err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt,
805 			     IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
806 			     "mconsole", (void *)sock);
807 	if (err) {
808 		printk(KERN_ERR "Failed to get IRQ for management console\n");
809 		goto out;
810 	}
811 
812 	if (notify_socket != NULL) {
813 		notify_socket = kstrdup(notify_socket, GFP_KERNEL);
814 		if (notify_socket != NULL)
815 			mconsole_notify(notify_socket, MCONSOLE_SOCKET,
816 					mconsole_socket_name,
817 					strlen(mconsole_socket_name) + 1);
818 		else printk(KERN_ERR "mconsole_setup failed to strdup "
819 			    "string\n");
820 	}
821 
822 	printk(KERN_INFO "mconsole (version %d) initialized on %s\n",
823 	       MCONSOLE_VERSION, mconsole_socket_name);
824 	return 0;
825 
826  out:
827 	os_close_file(sock);
828 	return 1;
829 }
830 
831 __initcall(mconsole_init);
832 
833 static int write_proc_mconsole(struct file *file, const char __user *buffer,
834 			       unsigned long count, void *data)
835 {
836 	char *buf;
837 
838 	buf = kmalloc(count + 1, GFP_KERNEL);
839 	if (buf == NULL)
840 		return -ENOMEM;
841 
842 	if (copy_from_user(buf, buffer, count)) {
843 		count = -EFAULT;
844 		goto out;
845 	}
846 
847 	buf[count] = '\0';
848 
849 	mconsole_notify(notify_socket, MCONSOLE_USER_NOTIFY, buf, count);
850  out:
851 	kfree(buf);
852 	return count;
853 }
854 
855 static int create_proc_mconsole(void)
856 {
857 	struct proc_dir_entry *ent;
858 
859 	if (notify_socket == NULL)
860 		return 0;
861 
862 	ent = create_proc_entry("mconsole", S_IFREG | 0200, NULL);
863 	if (ent == NULL) {
864 		printk(KERN_INFO "create_proc_mconsole : create_proc_entry "
865 		       "failed\n");
866 		return 0;
867 	}
868 
869 	ent->read_proc = NULL;
870 	ent->write_proc = write_proc_mconsole;
871 	return 0;
872 }
873 
874 static DEFINE_SPINLOCK(notify_spinlock);
875 
876 void lock_notify(void)
877 {
878 	spin_lock(&notify_spinlock);
879 }
880 
881 void unlock_notify(void)
882 {
883 	spin_unlock(&notify_spinlock);
884 }
885 
886 __initcall(create_proc_mconsole);
887 
888 #define NOTIFY "notify:"
889 
890 static int mconsole_setup(char *str)
891 {
892 	if (!strncmp(str, NOTIFY, strlen(NOTIFY))) {
893 		str += strlen(NOTIFY);
894 		notify_socket = str;
895 	}
896 	else printk(KERN_ERR "mconsole_setup : Unknown option - '%s'\n", str);
897 	return 1;
898 }
899 
900 __setup("mconsole=", mconsole_setup);
901 
902 __uml_help(mconsole_setup,
903 "mconsole=notify:<socket>\n"
904 "    Requests that the mconsole driver send a message to the named Unix\n"
905 "    socket containing the name of the mconsole socket.  This also serves\n"
906 "    to notify outside processes when UML has booted far enough to respond\n"
907 "    to mconsole requests.\n\n"
908 );
909 
910 static int notify_panic(struct notifier_block *self, unsigned long unused1,
911 			void *ptr)
912 {
913 	char *message = ptr;
914 
915 	if (notify_socket == NULL)
916 		return 0;
917 
918 	mconsole_notify(notify_socket, MCONSOLE_PANIC, message,
919 			strlen(message) + 1);
920 	return 0;
921 }
922 
923 static struct notifier_block panic_exit_notifier = {
924 	.notifier_call 		= notify_panic,
925 	.next 			= NULL,
926 	.priority 		= 1
927 };
928 
929 static int add_notifier(void)
930 {
931 	atomic_notifier_chain_register(&panic_notifier_list,
932 			&panic_exit_notifier);
933 	return 0;
934 }
935 
936 __initcall(add_notifier);
937 
938 char *mconsole_notify_socket(void)
939 {
940 	return notify_socket;
941 }
942 
943 EXPORT_SYMBOL(mconsole_notify_socket);
944