xref: /openbmc/linux/drivers/tty/vt/vt_ioctl.c (revision 24b1944f)
1 /*
2  *  Copyright (C) 1992 obz under the linux copyright
3  *
4  *  Dynamic diacritical handling - aeb@cwi.nl - Dec 1993
5  *  Dynamic keymap and string allocation - aeb@cwi.nl - May 1994
6  *  Restrict VT switching via ioctl() - grif@cs.ucr.edu - Dec 1995
7  *  Some code moved for less code duplication - Andi Kleen - Mar 1997
8  *  Check put/get_user, cleanups - acme@conectiva.com.br - Jun 2001
9  */
10 
11 #include <linux/types.h>
12 #include <linux/errno.h>
13 #include <linux/sched.h>
14 #include <linux/tty.h>
15 #include <linux/timer.h>
16 #include <linux/kernel.h>
17 #include <linux/compat.h>
18 #include <linux/module.h>
19 #include <linux/kd.h>
20 #include <linux/vt.h>
21 #include <linux/string.h>
22 #include <linux/slab.h>
23 #include <linux/major.h>
24 #include <linux/fs.h>
25 #include <linux/console.h>
26 #include <linux/consolemap.h>
27 #include <linux/signal.h>
28 #include <linux/suspend.h>
29 #include <linux/timex.h>
30 
31 #include <asm/io.h>
32 #include <asm/uaccess.h>
33 
34 #include <linux/kbd_kern.h>
35 #include <linux/vt_kern.h>
36 #include <linux/kbd_diacr.h>
37 #include <linux/selection.h>
38 
39 char vt_dont_switch;
40 extern struct tty_driver *console_driver;
41 
42 #define VT_IS_IN_USE(i)	(console_driver->ttys[i] && console_driver->ttys[i]->count)
43 #define VT_BUSY(i)	(VT_IS_IN_USE(i) || i == fg_console || vc_cons[i].d == sel_cons)
44 
45 /*
46  * Console (vt and kd) routines, as defined by USL SVR4 manual, and by
47  * experimentation and study of X386 SYSV handling.
48  *
49  * One point of difference: SYSV vt's are /dev/vtX, which X >= 0, and
50  * /dev/console is a separate ttyp. Under Linux, /dev/tty0 is /dev/console,
51  * and the vc start at /dev/ttyX, X >= 1. We maintain that here, so we will
52  * always treat our set of vt as numbered 1..MAX_NR_CONSOLES (corresponding to
53  * ttys 0..MAX_NR_CONSOLES-1). Explicitly naming VT 0 is illegal, but using
54  * /dev/tty0 (fg_console) as a target is legal, since an implicit aliasing
55  * to the current console is done by the main ioctl code.
56  */
57 
58 #ifdef CONFIG_X86
59 #include <linux/syscalls.h>
60 #endif
61 
62 static void complete_change_console(struct vc_data *vc);
63 
64 /*
65  *	User space VT_EVENT handlers
66  */
67 
68 struct vt_event_wait {
69 	struct list_head list;
70 	struct vt_event event;
71 	int done;
72 };
73 
74 static LIST_HEAD(vt_events);
75 static DEFINE_SPINLOCK(vt_event_lock);
76 static DECLARE_WAIT_QUEUE_HEAD(vt_event_waitqueue);
77 
78 /**
79  *	vt_event_post
80  *	@event: the event that occurred
81  *	@old: old console
82  *	@new: new console
83  *
84  *	Post an VT event to interested VT handlers
85  */
86 
87 void vt_event_post(unsigned int event, unsigned int old, unsigned int new)
88 {
89 	struct list_head *pos, *head;
90 	unsigned long flags;
91 	int wake = 0;
92 
93 	spin_lock_irqsave(&vt_event_lock, flags);
94 	head = &vt_events;
95 
96 	list_for_each(pos, head) {
97 		struct vt_event_wait *ve = list_entry(pos,
98 						struct vt_event_wait, list);
99 		if (!(ve->event.event & event))
100 			continue;
101 		ve->event.event = event;
102 		/* kernel view is consoles 0..n-1, user space view is
103 		   console 1..n with 0 meaning current, so we must bias */
104 		ve->event.oldev = old + 1;
105 		ve->event.newev = new + 1;
106 		wake = 1;
107 		ve->done = 1;
108 	}
109 	spin_unlock_irqrestore(&vt_event_lock, flags);
110 	if (wake)
111 		wake_up_interruptible(&vt_event_waitqueue);
112 }
113 
114 static void __vt_event_queue(struct vt_event_wait *vw)
115 {
116 	unsigned long flags;
117 	/* Prepare the event */
118 	INIT_LIST_HEAD(&vw->list);
119 	vw->done = 0;
120 	/* Queue our event */
121 	spin_lock_irqsave(&vt_event_lock, flags);
122 	list_add(&vw->list, &vt_events);
123 	spin_unlock_irqrestore(&vt_event_lock, flags);
124 }
125 
126 static void __vt_event_wait(struct vt_event_wait *vw)
127 {
128 	/* Wait for it to pass */
129 	wait_event_interruptible(vt_event_waitqueue, vw->done);
130 }
131 
132 static void __vt_event_dequeue(struct vt_event_wait *vw)
133 {
134 	unsigned long flags;
135 
136 	/* Dequeue it */
137 	spin_lock_irqsave(&vt_event_lock, flags);
138 	list_del(&vw->list);
139 	spin_unlock_irqrestore(&vt_event_lock, flags);
140 }
141 
142 /**
143  *	vt_event_wait		-	wait for an event
144  *	@vw: our event
145  *
146  *	Waits for an event to occur which completes our vt_event_wait
147  *	structure. On return the structure has wv->done set to 1 for success
148  *	or 0 if some event such as a signal ended the wait.
149  */
150 
151 static void vt_event_wait(struct vt_event_wait *vw)
152 {
153 	__vt_event_queue(vw);
154 	__vt_event_wait(vw);
155 	__vt_event_dequeue(vw);
156 }
157 
158 /**
159  *	vt_event_wait_ioctl	-	event ioctl handler
160  *	@arg: argument to ioctl
161  *
162  *	Implement the VT_WAITEVENT ioctl using the VT event interface
163  */
164 
165 static int vt_event_wait_ioctl(struct vt_event __user *event)
166 {
167 	struct vt_event_wait vw;
168 
169 	if (copy_from_user(&vw.event, event, sizeof(struct vt_event)))
170 		return -EFAULT;
171 	/* Highest supported event for now */
172 	if (vw.event.event & ~VT_MAX_EVENT)
173 		return -EINVAL;
174 
175 	vt_event_wait(&vw);
176 	/* If it occurred report it */
177 	if (vw.done) {
178 		if (copy_to_user(event, &vw.event, sizeof(struct vt_event)))
179 			return -EFAULT;
180 		return 0;
181 	}
182 	return -EINTR;
183 }
184 
185 /**
186  *	vt_waitactive	-	active console wait
187  *	@event: event code
188  *	@n: new console
189  *
190  *	Helper for event waits. Used to implement the legacy
191  *	event waiting ioctls in terms of events
192  */
193 
194 int vt_waitactive(int n)
195 {
196 	struct vt_event_wait vw;
197 	do {
198 		vw.event.event = VT_EVENT_SWITCH;
199 		__vt_event_queue(&vw);
200 		if (n == fg_console + 1) {
201 			__vt_event_dequeue(&vw);
202 			break;
203 		}
204 		__vt_event_wait(&vw);
205 		__vt_event_dequeue(&vw);
206 		if (vw.done == 0)
207 			return -EINTR;
208 	} while (vw.event.newev != n);
209 	return 0;
210 }
211 
212 /*
213  * these are the valid i/o ports we're allowed to change. they map all the
214  * video ports
215  */
216 #define GPFIRST 0x3b4
217 #define GPLAST 0x3df
218 #define GPNUM (GPLAST - GPFIRST + 1)
219 
220 
221 
222 static inline int
223 do_fontx_ioctl(int cmd, struct consolefontdesc __user *user_cfd, int perm, struct console_font_op *op)
224 {
225 	struct consolefontdesc cfdarg;
226 	int i;
227 
228 	if (copy_from_user(&cfdarg, user_cfd, sizeof(struct consolefontdesc)))
229 		return -EFAULT;
230 
231 	switch (cmd) {
232 	case PIO_FONTX:
233 		if (!perm)
234 			return -EPERM;
235 		op->op = KD_FONT_OP_SET;
236 		op->flags = KD_FONT_FLAG_OLD;
237 		op->width = 8;
238 		op->height = cfdarg.charheight;
239 		op->charcount = cfdarg.charcount;
240 		op->data = cfdarg.chardata;
241 		return con_font_op(vc_cons[fg_console].d, op);
242 	case GIO_FONTX: {
243 		op->op = KD_FONT_OP_GET;
244 		op->flags = KD_FONT_FLAG_OLD;
245 		op->width = 8;
246 		op->height = cfdarg.charheight;
247 		op->charcount = cfdarg.charcount;
248 		op->data = cfdarg.chardata;
249 		i = con_font_op(vc_cons[fg_console].d, op);
250 		if (i)
251 			return i;
252 		cfdarg.charheight = op->height;
253 		cfdarg.charcount = op->charcount;
254 		if (copy_to_user(user_cfd, &cfdarg, sizeof(struct consolefontdesc)))
255 			return -EFAULT;
256 		return 0;
257 		}
258 	}
259 	return -EINVAL;
260 }
261 
262 static inline int
263 do_unimap_ioctl(int cmd, struct unimapdesc __user *user_ud, int perm, struct vc_data *vc)
264 {
265 	struct unimapdesc tmp;
266 
267 	if (copy_from_user(&tmp, user_ud, sizeof tmp))
268 		return -EFAULT;
269 	if (tmp.entries)
270 		if (!access_ok(VERIFY_WRITE, tmp.entries,
271 				tmp.entry_ct*sizeof(struct unipair)))
272 			return -EFAULT;
273 	switch (cmd) {
274 	case PIO_UNIMAP:
275 		if (!perm)
276 			return -EPERM;
277 		return con_set_unimap(vc, tmp.entry_ct, tmp.entries);
278 	case GIO_UNIMAP:
279 		if (!perm && fg_console != vc->vc_num)
280 			return -EPERM;
281 		return con_get_unimap(vc, tmp.entry_ct, &(user_ud->entry_ct), tmp.entries);
282 	}
283 	return 0;
284 }
285 
286 /* deallocate a single console, if possible (leave 0) */
287 static int vt_disallocate(unsigned int vc_num)
288 {
289 	struct vc_data *vc = NULL;
290 	int ret = 0;
291 
292 	if (!vc_num)
293 		return 0;
294 
295 	console_lock();
296 	if (VT_BUSY(vc_num))
297 		ret = -EBUSY;
298 	else
299 		vc = vc_deallocate(vc_num);
300 	console_unlock();
301 
302 	if (vc && vc_num >= MIN_NR_CONSOLES) {
303 		tty_port_destroy(&vc->port);
304 		kfree(vc);
305 	}
306 
307 	return ret;
308 }
309 
310 /* deallocate all unused consoles, but leave 0 */
311 static void vt_disallocate_all(void)
312 {
313 	struct vc_data *vc[MAX_NR_CONSOLES];
314 	int i;
315 
316 	console_lock();
317 	for (i = 1; i < MAX_NR_CONSOLES; i++)
318 		if (!VT_BUSY(i))
319 			vc[i] = vc_deallocate(i);
320 		else
321 			vc[i] = NULL;
322 	console_unlock();
323 
324 	for (i = 1; i < MAX_NR_CONSOLES; i++) {
325 		if (vc[i] && i >= MIN_NR_CONSOLES) {
326 			tty_port_destroy(&vc[i]->port);
327 			kfree(vc[i]);
328 		}
329 	}
330 }
331 
332 
333 /*
334  * We handle the console-specific ioctl's here.  We allow the
335  * capability to modify any console, not just the fg_console.
336  */
337 int vt_ioctl(struct tty_struct *tty,
338 	     unsigned int cmd, unsigned long arg)
339 {
340 	struct vc_data *vc = tty->driver_data;
341 	struct console_font_op op;	/* used in multiple places here */
342 	unsigned int console;
343 	unsigned char ucval;
344 	unsigned int uival;
345 	void __user *up = (void __user *)arg;
346 	int i, perm;
347 	int ret = 0;
348 
349 	console = vc->vc_num;
350 
351 
352 	if (!vc_cons_allocated(console)) { 	/* impossible? */
353 		ret = -ENOIOCTLCMD;
354 		goto out;
355 	}
356 
357 
358 	/*
359 	 * To have permissions to do most of the vt ioctls, we either have
360 	 * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
361 	 */
362 	perm = 0;
363 	if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
364 		perm = 1;
365 
366 	switch (cmd) {
367 	case TIOCLINUX:
368 		ret = tioclinux(tty, arg);
369 		break;
370 	case KIOCSOUND:
371 		if (!perm)
372 			return -EPERM;
373 		/*
374 		 * The use of PIT_TICK_RATE is historic, it used to be
375 		 * the platform-dependent CLOCK_TICK_RATE between 2.6.12
376 		 * and 2.6.36, which was a minor but unfortunate ABI
377 		 * change. kd_mksound is locked by the input layer.
378 		 */
379 		if (arg)
380 			arg = PIT_TICK_RATE / arg;
381 		kd_mksound(arg, 0);
382 		break;
383 
384 	case KDMKTONE:
385 		if (!perm)
386 			return -EPERM;
387 	{
388 		unsigned int ticks, count;
389 
390 		/*
391 		 * Generate the tone for the appropriate number of ticks.
392 		 * If the time is zero, turn off sound ourselves.
393 		 */
394 		ticks = HZ * ((arg >> 16) & 0xffff) / 1000;
395 		count = ticks ? (arg & 0xffff) : 0;
396 		if (count)
397 			count = PIT_TICK_RATE / count;
398 		kd_mksound(count, ticks);
399 		break;
400 	}
401 
402 	case KDGKBTYPE:
403 		/*
404 		 * this is naïve.
405 		 */
406 		ucval = KB_101;
407 		ret = put_user(ucval, (char __user *)arg);
408 		break;
409 
410 		/*
411 		 * These cannot be implemented on any machine that implements
412 		 * ioperm() in user level (such as Alpha PCs) or not at all.
413 		 *
414 		 * XXX: you should never use these, just call ioperm directly..
415 		 */
416 #ifdef CONFIG_X86
417 	case KDADDIO:
418 	case KDDELIO:
419 		/*
420 		 * KDADDIO and KDDELIO may be able to add ports beyond what
421 		 * we reject here, but to be safe...
422 		 *
423 		 * These are locked internally via sys_ioperm
424 		 */
425 		if (arg < GPFIRST || arg > GPLAST) {
426 			ret = -EINVAL;
427 			break;
428 		}
429 		ret = sys_ioperm(arg, 1, (cmd == KDADDIO)) ? -ENXIO : 0;
430 		break;
431 
432 	case KDENABIO:
433 	case KDDISABIO:
434 		ret = sys_ioperm(GPFIRST, GPNUM,
435 				  (cmd == KDENABIO)) ? -ENXIO : 0;
436 		break;
437 #endif
438 
439 	/* Linux m68k/i386 interface for setting the keyboard delay/repeat rate */
440 
441 	case KDKBDREP:
442 	{
443 		struct kbd_repeat kbrep;
444 
445 		if (!capable(CAP_SYS_TTY_CONFIG))
446 			return -EPERM;
447 
448 		if (copy_from_user(&kbrep, up, sizeof(struct kbd_repeat))) {
449 			ret =  -EFAULT;
450 			break;
451 		}
452 		ret = kbd_rate(&kbrep);
453 		if (ret)
454 			break;
455 		if (copy_to_user(up, &kbrep, sizeof(struct kbd_repeat)))
456 			ret = -EFAULT;
457 		break;
458 	}
459 
460 	case KDSETMODE:
461 		/*
462 		 * currently, setting the mode from KD_TEXT to KD_GRAPHICS
463 		 * doesn't do a whole lot. i'm not sure if it should do any
464 		 * restoration of modes or what...
465 		 *
466 		 * XXX It should at least call into the driver, fbdev's definitely
467 		 * need to restore their engine state. --BenH
468 		 */
469 		if (!perm)
470 			return -EPERM;
471 		switch (arg) {
472 		case KD_GRAPHICS:
473 			break;
474 		case KD_TEXT0:
475 		case KD_TEXT1:
476 			arg = KD_TEXT;
477 		case KD_TEXT:
478 			break;
479 		default:
480 			ret = -EINVAL;
481 			goto out;
482 		}
483 		/* FIXME: this needs the console lock extending */
484 		if (vc->vc_mode == (unsigned char) arg)
485 			break;
486 		vc->vc_mode = (unsigned char) arg;
487 		if (console != fg_console)
488 			break;
489 		/*
490 		 * explicitly blank/unblank the screen if switching modes
491 		 */
492 		console_lock();
493 		if (arg == KD_TEXT)
494 			do_unblank_screen(1);
495 		else
496 			do_blank_screen(1);
497 		console_unlock();
498 		break;
499 
500 	case KDGETMODE:
501 		uival = vc->vc_mode;
502 		goto setint;
503 
504 	case KDMAPDISP:
505 	case KDUNMAPDISP:
506 		/*
507 		 * these work like a combination of mmap and KDENABIO.
508 		 * this could be easily finished.
509 		 */
510 		ret = -EINVAL;
511 		break;
512 
513 	case KDSKBMODE:
514 		if (!perm)
515 			return -EPERM;
516 		ret = vt_do_kdskbmode(console, arg);
517 		if (ret == 0)
518 			tty_ldisc_flush(tty);
519 		break;
520 
521 	case KDGKBMODE:
522 		uival = vt_do_kdgkbmode(console);
523 		ret = put_user(uival, (int __user *)arg);
524 		break;
525 
526 	/* this could be folded into KDSKBMODE, but for compatibility
527 	   reasons it is not so easy to fold KDGKBMETA into KDGKBMODE */
528 	case KDSKBMETA:
529 		ret = vt_do_kdskbmeta(console, arg);
530 		break;
531 
532 	case KDGKBMETA:
533 		/* FIXME: should review whether this is worth locking */
534 		uival = vt_do_kdgkbmeta(console);
535 	setint:
536 		ret = put_user(uival, (int __user *)arg);
537 		break;
538 
539 	case KDGETKEYCODE:
540 	case KDSETKEYCODE:
541 		if(!capable(CAP_SYS_TTY_CONFIG))
542 			perm = 0;
543 		ret = vt_do_kbkeycode_ioctl(cmd, up, perm);
544 		break;
545 
546 	case KDGKBENT:
547 	case KDSKBENT:
548 		ret = vt_do_kdsk_ioctl(cmd, up, perm, console);
549 		break;
550 
551 	case KDGKBSENT:
552 	case KDSKBSENT:
553 		ret = vt_do_kdgkb_ioctl(cmd, up, perm);
554 		break;
555 
556 	/* Diacritical processing. Handled in keyboard.c as it has
557 	   to operate on the keyboard locks and structures */
558 	case KDGKBDIACR:
559 	case KDGKBDIACRUC:
560 	case KDSKBDIACR:
561 	case KDSKBDIACRUC:
562 		ret = vt_do_diacrit(cmd, up, perm);
563 		break;
564 
565 	/* the ioctls below read/set the flags usually shown in the leds */
566 	/* don't use them - they will go away without warning */
567 	case KDGKBLED:
568 	case KDSKBLED:
569 	case KDGETLED:
570 	case KDSETLED:
571 		ret = vt_do_kdskled(console, cmd, arg, perm);
572 		break;
573 
574 	/*
575 	 * A process can indicate its willingness to accept signals
576 	 * generated by pressing an appropriate key combination.
577 	 * Thus, one can have a daemon that e.g. spawns a new console
578 	 * upon a keypress and then changes to it.
579 	 * See also the kbrequest field of inittab(5).
580 	 */
581 	case KDSIGACCEPT:
582 	{
583 		if (!perm || !capable(CAP_KILL))
584 			return -EPERM;
585 		if (!valid_signal(arg) || arg < 1 || arg == SIGKILL)
586 			ret = -EINVAL;
587 		else {
588 			spin_lock_irq(&vt_spawn_con.lock);
589 			put_pid(vt_spawn_con.pid);
590 			vt_spawn_con.pid = get_pid(task_pid(current));
591 			vt_spawn_con.sig = arg;
592 			spin_unlock_irq(&vt_spawn_con.lock);
593 		}
594 		break;
595 	}
596 
597 	case VT_SETMODE:
598 	{
599 		struct vt_mode tmp;
600 
601 		if (!perm)
602 			return -EPERM;
603 		if (copy_from_user(&tmp, up, sizeof(struct vt_mode))) {
604 			ret = -EFAULT;
605 			goto out;
606 		}
607 		if (tmp.mode != VT_AUTO && tmp.mode != VT_PROCESS) {
608 			ret = -EINVAL;
609 			goto out;
610 		}
611 		console_lock();
612 		vc->vt_mode = tmp;
613 		/* the frsig is ignored, so we set it to 0 */
614 		vc->vt_mode.frsig = 0;
615 		put_pid(vc->vt_pid);
616 		vc->vt_pid = get_pid(task_pid(current));
617 		/* no switch is required -- saw@shade.msu.ru */
618 		vc->vt_newvt = -1;
619 		console_unlock();
620 		break;
621 	}
622 
623 	case VT_GETMODE:
624 	{
625 		struct vt_mode tmp;
626 		int rc;
627 
628 		console_lock();
629 		memcpy(&tmp, &vc->vt_mode, sizeof(struct vt_mode));
630 		console_unlock();
631 
632 		rc = copy_to_user(up, &tmp, sizeof(struct vt_mode));
633 		if (rc)
634 			ret = -EFAULT;
635 		break;
636 	}
637 
638 	/*
639 	 * Returns global vt state. Note that VT 0 is always open, since
640 	 * it's an alias for the current VT, and people can't use it here.
641 	 * We cannot return state for more than 16 VTs, since v_state is short.
642 	 */
643 	case VT_GETSTATE:
644 	{
645 		struct vt_stat __user *vtstat = up;
646 		unsigned short state, mask;
647 
648 		/* Review: FIXME: Console lock ? */
649 		if (put_user(fg_console + 1, &vtstat->v_active))
650 			ret = -EFAULT;
651 		else {
652 			state = 1;	/* /dev/tty0 is always open */
653 			for (i = 0, mask = 2; i < MAX_NR_CONSOLES && mask;
654 							++i, mask <<= 1)
655 				if (VT_IS_IN_USE(i))
656 					state |= mask;
657 			ret = put_user(state, &vtstat->v_state);
658 		}
659 		break;
660 	}
661 
662 	/*
663 	 * Returns the first available (non-opened) console.
664 	 */
665 	case VT_OPENQRY:
666 		/* FIXME: locking ? - but then this is a stupid API */
667 		for (i = 0; i < MAX_NR_CONSOLES; ++i)
668 			if (! VT_IS_IN_USE(i))
669 				break;
670 		uival = i < MAX_NR_CONSOLES ? (i+1) : -1;
671 		goto setint;
672 
673 	/*
674 	 * ioctl(fd, VT_ACTIVATE, num) will cause us to switch to vt # num,
675 	 * with num >= 1 (switches to vt 0, our console, are not allowed, just
676 	 * to preserve sanity).
677 	 */
678 	case VT_ACTIVATE:
679 		if (!perm)
680 			return -EPERM;
681 		if (arg == 0 || arg > MAX_NR_CONSOLES)
682 			ret =  -ENXIO;
683 		else {
684 			arg--;
685 			console_lock();
686 			ret = vc_allocate(arg);
687 			console_unlock();
688 			if (ret)
689 				break;
690 			set_console(arg);
691 		}
692 		break;
693 
694 	case VT_SETACTIVATE:
695 	{
696 		struct vt_setactivate vsa;
697 
698 		if (!perm)
699 			return -EPERM;
700 
701 		if (copy_from_user(&vsa, (struct vt_setactivate __user *)arg,
702 					sizeof(struct vt_setactivate))) {
703 			ret = -EFAULT;
704 			goto out;
705 		}
706 		if (vsa.console == 0 || vsa.console > MAX_NR_CONSOLES)
707 			ret = -ENXIO;
708 		else {
709 			vsa.console--;
710 			console_lock();
711 			ret = vc_allocate(vsa.console);
712 			if (ret == 0) {
713 				struct vc_data *nvc;
714 				/* This is safe providing we don't drop the
715 				   console sem between vc_allocate and
716 				   finishing referencing nvc */
717 				nvc = vc_cons[vsa.console].d;
718 				nvc->vt_mode = vsa.mode;
719 				nvc->vt_mode.frsig = 0;
720 				put_pid(nvc->vt_pid);
721 				nvc->vt_pid = get_pid(task_pid(current));
722 			}
723 			console_unlock();
724 			if (ret)
725 				break;
726 			/* Commence switch and lock */
727 			/* Review set_console locks */
728 			set_console(vsa.console);
729 		}
730 		break;
731 	}
732 
733 	/*
734 	 * wait until the specified VT has been activated
735 	 */
736 	case VT_WAITACTIVE:
737 		if (!perm)
738 			return -EPERM;
739 		if (arg == 0 || arg > MAX_NR_CONSOLES)
740 			ret = -ENXIO;
741 		else
742 			ret = vt_waitactive(arg);
743 		break;
744 
745 	/*
746 	 * If a vt is under process control, the kernel will not switch to it
747 	 * immediately, but postpone the operation until the process calls this
748 	 * ioctl, allowing the switch to complete.
749 	 *
750 	 * According to the X sources this is the behavior:
751 	 *	0:	pending switch-from not OK
752 	 *	1:	pending switch-from OK
753 	 *	2:	completed switch-to OK
754 	 */
755 	case VT_RELDISP:
756 		if (!perm)
757 			return -EPERM;
758 
759 		console_lock();
760 		if (vc->vt_mode.mode != VT_PROCESS) {
761 			console_unlock();
762 			ret = -EINVAL;
763 			break;
764 		}
765 		/*
766 		 * Switching-from response
767 		 */
768 		if (vc->vt_newvt >= 0) {
769 			if (arg == 0)
770 				/*
771 				 * Switch disallowed, so forget we were trying
772 				 * to do it.
773 				 */
774 				vc->vt_newvt = -1;
775 
776 			else {
777 				/*
778 				 * The current vt has been released, so
779 				 * complete the switch.
780 				 */
781 				int newvt;
782 				newvt = vc->vt_newvt;
783 				vc->vt_newvt = -1;
784 				ret = vc_allocate(newvt);
785 				if (ret) {
786 					console_unlock();
787 					break;
788 				}
789 				/*
790 				 * When we actually do the console switch,
791 				 * make sure we are atomic with respect to
792 				 * other console switches..
793 				 */
794 				complete_change_console(vc_cons[newvt].d);
795 			}
796 		} else {
797 			/*
798 			 * Switched-to response
799 			 */
800 			/*
801 			 * If it's just an ACK, ignore it
802 			 */
803 			if (arg != VT_ACKACQ)
804 				ret = -EINVAL;
805 		}
806 		console_unlock();
807 		break;
808 
809 	 /*
810 	  * Disallocate memory associated to VT (but leave VT1)
811 	  */
812 	 case VT_DISALLOCATE:
813 		if (arg > MAX_NR_CONSOLES) {
814 			ret = -ENXIO;
815 			break;
816 		}
817 		if (arg == 0)
818 			vt_disallocate_all();
819 		else
820 			ret = vt_disallocate(--arg);
821 		break;
822 
823 	case VT_RESIZE:
824 	{
825 		struct vt_sizes __user *vtsizes = up;
826 		struct vc_data *vc;
827 
828 		ushort ll,cc;
829 		if (!perm)
830 			return -EPERM;
831 		if (get_user(ll, &vtsizes->v_rows) ||
832 		    get_user(cc, &vtsizes->v_cols))
833 			ret = -EFAULT;
834 		else {
835 			console_lock();
836 			for (i = 0; i < MAX_NR_CONSOLES; i++) {
837 				vc = vc_cons[i].d;
838 
839 				if (vc) {
840 					vc->vc_resize_user = 1;
841 					/* FIXME: review v tty lock */
842 					vc_resize(vc_cons[i].d, cc, ll);
843 				}
844 			}
845 			console_unlock();
846 		}
847 		break;
848 	}
849 
850 	case VT_RESIZEX:
851 	{
852 		struct vt_consize __user *vtconsize = up;
853 		ushort ll,cc,vlin,clin,vcol,ccol;
854 		if (!perm)
855 			return -EPERM;
856 		if (!access_ok(VERIFY_READ, vtconsize,
857 				sizeof(struct vt_consize))) {
858 			ret = -EFAULT;
859 			break;
860 		}
861 		/* FIXME: Should check the copies properly */
862 		__get_user(ll, &vtconsize->v_rows);
863 		__get_user(cc, &vtconsize->v_cols);
864 		__get_user(vlin, &vtconsize->v_vlin);
865 		__get_user(clin, &vtconsize->v_clin);
866 		__get_user(vcol, &vtconsize->v_vcol);
867 		__get_user(ccol, &vtconsize->v_ccol);
868 		vlin = vlin ? vlin : vc->vc_scan_lines;
869 		if (clin) {
870 			if (ll) {
871 				if (ll != vlin/clin) {
872 					/* Parameters don't add up */
873 					ret = -EINVAL;
874 					break;
875 				}
876 			} else
877 				ll = vlin/clin;
878 		}
879 		if (vcol && ccol) {
880 			if (cc) {
881 				if (cc != vcol/ccol) {
882 					ret = -EINVAL;
883 					break;
884 				}
885 			} else
886 				cc = vcol/ccol;
887 		}
888 
889 		if (clin > 32) {
890 			ret =  -EINVAL;
891 			break;
892 		}
893 
894 		for (i = 0; i < MAX_NR_CONSOLES; i++) {
895 			if (!vc_cons[i].d)
896 				continue;
897 			console_lock();
898 			if (vlin)
899 				vc_cons[i].d->vc_scan_lines = vlin;
900 			if (clin)
901 				vc_cons[i].d->vc_font.height = clin;
902 			vc_cons[i].d->vc_resize_user = 1;
903 			vc_resize(vc_cons[i].d, cc, ll);
904 			console_unlock();
905 		}
906 		break;
907 	}
908 
909 	case PIO_FONT: {
910 		if (!perm)
911 			return -EPERM;
912 		op.op = KD_FONT_OP_SET;
913 		op.flags = KD_FONT_FLAG_OLD | KD_FONT_FLAG_DONT_RECALC;	/* Compatibility */
914 		op.width = 8;
915 		op.height = 0;
916 		op.charcount = 256;
917 		op.data = up;
918 		ret = con_font_op(vc_cons[fg_console].d, &op);
919 		break;
920 	}
921 
922 	case GIO_FONT: {
923 		op.op = KD_FONT_OP_GET;
924 		op.flags = KD_FONT_FLAG_OLD;
925 		op.width = 8;
926 		op.height = 32;
927 		op.charcount = 256;
928 		op.data = up;
929 		ret = con_font_op(vc_cons[fg_console].d, &op);
930 		break;
931 	}
932 
933 	case PIO_CMAP:
934                 if (!perm)
935 			ret = -EPERM;
936 		else
937 	                ret = con_set_cmap(up);
938 		break;
939 
940 	case GIO_CMAP:
941                 ret = con_get_cmap(up);
942 		break;
943 
944 	case PIO_FONTX:
945 	case GIO_FONTX:
946 		ret = do_fontx_ioctl(cmd, up, perm, &op);
947 		break;
948 
949 	case PIO_FONTRESET:
950 	{
951 		if (!perm)
952 			return -EPERM;
953 
954 #ifdef BROKEN_GRAPHICS_PROGRAMS
955 		/* With BROKEN_GRAPHICS_PROGRAMS defined, the default
956 		   font is not saved. */
957 		ret = -ENOSYS;
958 		break;
959 #else
960 		{
961 		op.op = KD_FONT_OP_SET_DEFAULT;
962 		op.data = NULL;
963 		ret = con_font_op(vc_cons[fg_console].d, &op);
964 		if (ret)
965 			break;
966 		console_lock();
967 		con_set_default_unimap(vc_cons[fg_console].d);
968 		console_unlock();
969 		break;
970 		}
971 #endif
972 	}
973 
974 	case KDFONTOP: {
975 		if (copy_from_user(&op, up, sizeof(op))) {
976 			ret = -EFAULT;
977 			break;
978 		}
979 		if (!perm && op.op != KD_FONT_OP_GET)
980 			return -EPERM;
981 		ret = con_font_op(vc, &op);
982 		if (ret)
983 			break;
984 		if (copy_to_user(up, &op, sizeof(op)))
985 			ret = -EFAULT;
986 		break;
987 	}
988 
989 	case PIO_SCRNMAP:
990 		if (!perm)
991 			ret = -EPERM;
992 		else
993 			ret = con_set_trans_old(up);
994 		break;
995 
996 	case GIO_SCRNMAP:
997 		ret = con_get_trans_old(up);
998 		break;
999 
1000 	case PIO_UNISCRNMAP:
1001 		if (!perm)
1002 			ret = -EPERM;
1003 		else
1004 			ret = con_set_trans_new(up);
1005 		break;
1006 
1007 	case GIO_UNISCRNMAP:
1008 		ret = con_get_trans_new(up);
1009 		break;
1010 
1011 	case PIO_UNIMAPCLR:
1012 	      { struct unimapinit ui;
1013 		if (!perm)
1014 			return -EPERM;
1015 		ret = copy_from_user(&ui, up, sizeof(struct unimapinit));
1016 		if (ret)
1017 			ret = -EFAULT;
1018 		else
1019 			con_clear_unimap(vc, &ui);
1020 		break;
1021 	      }
1022 
1023 	case PIO_UNIMAP:
1024 	case GIO_UNIMAP:
1025 		ret = do_unimap_ioctl(cmd, up, perm, vc);
1026 		break;
1027 
1028 	case VT_LOCKSWITCH:
1029 		if (!capable(CAP_SYS_TTY_CONFIG))
1030 			return -EPERM;
1031 		vt_dont_switch = 1;
1032 		break;
1033 	case VT_UNLOCKSWITCH:
1034 		if (!capable(CAP_SYS_TTY_CONFIG))
1035 			return -EPERM;
1036 		vt_dont_switch = 0;
1037 		break;
1038 	case VT_GETHIFONTMASK:
1039 		ret = put_user(vc->vc_hi_font_mask,
1040 					(unsigned short __user *)arg);
1041 		break;
1042 	case VT_WAITEVENT:
1043 		ret = vt_event_wait_ioctl((struct vt_event __user *)arg);
1044 		break;
1045 	default:
1046 		ret = -ENOIOCTLCMD;
1047 	}
1048 out:
1049 	return ret;
1050 }
1051 
1052 void reset_vc(struct vc_data *vc)
1053 {
1054 	vc->vc_mode = KD_TEXT;
1055 	vt_reset_unicode(vc->vc_num);
1056 	vc->vt_mode.mode = VT_AUTO;
1057 	vc->vt_mode.waitv = 0;
1058 	vc->vt_mode.relsig = 0;
1059 	vc->vt_mode.acqsig = 0;
1060 	vc->vt_mode.frsig = 0;
1061 	put_pid(vc->vt_pid);
1062 	vc->vt_pid = NULL;
1063 	vc->vt_newvt = -1;
1064 	if (!in_interrupt())    /* Via keyboard.c:SAK() - akpm */
1065 		reset_palette(vc);
1066 }
1067 
1068 void vc_SAK(struct work_struct *work)
1069 {
1070 	struct vc *vc_con =
1071 		container_of(work, struct vc, SAK_work);
1072 	struct vc_data *vc;
1073 	struct tty_struct *tty;
1074 
1075 	console_lock();
1076 	vc = vc_con->d;
1077 	if (vc) {
1078 		/* FIXME: review tty ref counting */
1079 		tty = vc->port.tty;
1080 		/*
1081 		 * SAK should also work in all raw modes and reset
1082 		 * them properly.
1083 		 */
1084 		if (tty)
1085 			__do_SAK(tty);
1086 		reset_vc(vc);
1087 	}
1088 	console_unlock();
1089 }
1090 
1091 #ifdef CONFIG_COMPAT
1092 
1093 struct compat_consolefontdesc {
1094 	unsigned short charcount;       /* characters in font (256 or 512) */
1095 	unsigned short charheight;      /* scan lines per character (1-32) */
1096 	compat_caddr_t chardata;	/* font data in expanded form */
1097 };
1098 
1099 static inline int
1100 compat_fontx_ioctl(int cmd, struct compat_consolefontdesc __user *user_cfd,
1101 			 int perm, struct console_font_op *op)
1102 {
1103 	struct compat_consolefontdesc cfdarg;
1104 	int i;
1105 
1106 	if (copy_from_user(&cfdarg, user_cfd, sizeof(struct compat_consolefontdesc)))
1107 		return -EFAULT;
1108 
1109 	switch (cmd) {
1110 	case PIO_FONTX:
1111 		if (!perm)
1112 			return -EPERM;
1113 		op->op = KD_FONT_OP_SET;
1114 		op->flags = KD_FONT_FLAG_OLD;
1115 		op->width = 8;
1116 		op->height = cfdarg.charheight;
1117 		op->charcount = cfdarg.charcount;
1118 		op->data = compat_ptr(cfdarg.chardata);
1119 		return con_font_op(vc_cons[fg_console].d, op);
1120 	case GIO_FONTX:
1121 		op->op = KD_FONT_OP_GET;
1122 		op->flags = KD_FONT_FLAG_OLD;
1123 		op->width = 8;
1124 		op->height = cfdarg.charheight;
1125 		op->charcount = cfdarg.charcount;
1126 		op->data = compat_ptr(cfdarg.chardata);
1127 		i = con_font_op(vc_cons[fg_console].d, op);
1128 		if (i)
1129 			return i;
1130 		cfdarg.charheight = op->height;
1131 		cfdarg.charcount = op->charcount;
1132 		if (copy_to_user(user_cfd, &cfdarg, sizeof(struct compat_consolefontdesc)))
1133 			return -EFAULT;
1134 		return 0;
1135 	}
1136 	return -EINVAL;
1137 }
1138 
1139 struct compat_console_font_op {
1140 	compat_uint_t op;        /* operation code KD_FONT_OP_* */
1141 	compat_uint_t flags;     /* KD_FONT_FLAG_* */
1142 	compat_uint_t width, height;     /* font size */
1143 	compat_uint_t charcount;
1144 	compat_caddr_t data;    /* font data with height fixed to 32 */
1145 };
1146 
1147 static inline int
1148 compat_kdfontop_ioctl(struct compat_console_font_op __user *fontop,
1149 			 int perm, struct console_font_op *op, struct vc_data *vc)
1150 {
1151 	int i;
1152 
1153 	if (copy_from_user(op, fontop, sizeof(struct compat_console_font_op)))
1154 		return -EFAULT;
1155 	if (!perm && op->op != KD_FONT_OP_GET)
1156 		return -EPERM;
1157 	op->data = compat_ptr(((struct compat_console_font_op *)op)->data);
1158 	i = con_font_op(vc, op);
1159 	if (i)
1160 		return i;
1161 	((struct compat_console_font_op *)op)->data = (unsigned long)op->data;
1162 	if (copy_to_user(fontop, op, sizeof(struct compat_console_font_op)))
1163 		return -EFAULT;
1164 	return 0;
1165 }
1166 
1167 struct compat_unimapdesc {
1168 	unsigned short entry_ct;
1169 	compat_caddr_t entries;
1170 };
1171 
1172 static inline int
1173 compat_unimap_ioctl(unsigned int cmd, struct compat_unimapdesc __user *user_ud,
1174 			 int perm, struct vc_data *vc)
1175 {
1176 	struct compat_unimapdesc tmp;
1177 	struct unipair __user *tmp_entries;
1178 
1179 	if (copy_from_user(&tmp, user_ud, sizeof tmp))
1180 		return -EFAULT;
1181 	tmp_entries = compat_ptr(tmp.entries);
1182 	if (tmp_entries)
1183 		if (!access_ok(VERIFY_WRITE, tmp_entries,
1184 				tmp.entry_ct*sizeof(struct unipair)))
1185 			return -EFAULT;
1186 	switch (cmd) {
1187 	case PIO_UNIMAP:
1188 		if (!perm)
1189 			return -EPERM;
1190 		return con_set_unimap(vc, tmp.entry_ct, tmp_entries);
1191 	case GIO_UNIMAP:
1192 		if (!perm && fg_console != vc->vc_num)
1193 			return -EPERM;
1194 		return con_get_unimap(vc, tmp.entry_ct, &(user_ud->entry_ct), tmp_entries);
1195 	}
1196 	return 0;
1197 }
1198 
1199 long vt_compat_ioctl(struct tty_struct *tty,
1200 	     unsigned int cmd, unsigned long arg)
1201 {
1202 	struct vc_data *vc = tty->driver_data;
1203 	struct console_font_op op;	/* used in multiple places here */
1204 	unsigned int console;
1205 	void __user *up = (void __user *)arg;
1206 	int perm;
1207 	int ret = 0;
1208 
1209 	console = vc->vc_num;
1210 
1211 	if (!vc_cons_allocated(console)) { 	/* impossible? */
1212 		ret = -ENOIOCTLCMD;
1213 		goto out;
1214 	}
1215 
1216 	/*
1217 	 * To have permissions to do most of the vt ioctls, we either have
1218 	 * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
1219 	 */
1220 	perm = 0;
1221 	if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
1222 		perm = 1;
1223 
1224 	switch (cmd) {
1225 	/*
1226 	 * these need special handlers for incompatible data structures
1227 	 */
1228 	case PIO_FONTX:
1229 	case GIO_FONTX:
1230 		ret = compat_fontx_ioctl(cmd, up, perm, &op);
1231 		break;
1232 
1233 	case KDFONTOP:
1234 		ret = compat_kdfontop_ioctl(up, perm, &op, vc);
1235 		break;
1236 
1237 	case PIO_UNIMAP:
1238 	case GIO_UNIMAP:
1239 		ret = compat_unimap_ioctl(cmd, up, perm, vc);
1240 		break;
1241 
1242 	/*
1243 	 * all these treat 'arg' as an integer
1244 	 */
1245 	case KIOCSOUND:
1246 	case KDMKTONE:
1247 #ifdef CONFIG_X86
1248 	case KDADDIO:
1249 	case KDDELIO:
1250 #endif
1251 	case KDSETMODE:
1252 	case KDMAPDISP:
1253 	case KDUNMAPDISP:
1254 	case KDSKBMODE:
1255 	case KDSKBMETA:
1256 	case KDSKBLED:
1257 	case KDSETLED:
1258 	case KDSIGACCEPT:
1259 	case VT_ACTIVATE:
1260 	case VT_WAITACTIVE:
1261 	case VT_RELDISP:
1262 	case VT_DISALLOCATE:
1263 	case VT_RESIZE:
1264 	case VT_RESIZEX:
1265 		goto fallback;
1266 
1267 	/*
1268 	 * the rest has a compatible data structure behind arg,
1269 	 * but we have to convert it to a proper 64 bit pointer.
1270 	 */
1271 	default:
1272 		arg = (unsigned long)compat_ptr(arg);
1273 		goto fallback;
1274 	}
1275 out:
1276 	return ret;
1277 
1278 fallback:
1279 	return vt_ioctl(tty, cmd, arg);
1280 }
1281 
1282 
1283 #endif /* CONFIG_COMPAT */
1284 
1285 
1286 /*
1287  * Performs the back end of a vt switch. Called under the console
1288  * semaphore.
1289  */
1290 static void complete_change_console(struct vc_data *vc)
1291 {
1292 	unsigned char old_vc_mode;
1293 	int old = fg_console;
1294 
1295 	last_console = fg_console;
1296 
1297 	/*
1298 	 * If we're switching, we could be going from KD_GRAPHICS to
1299 	 * KD_TEXT mode or vice versa, which means we need to blank or
1300 	 * unblank the screen later.
1301 	 */
1302 	old_vc_mode = vc_cons[fg_console].d->vc_mode;
1303 	switch_screen(vc);
1304 
1305 	/*
1306 	 * This can't appear below a successful kill_pid().  If it did,
1307 	 * then the *blank_screen operation could occur while X, having
1308 	 * received acqsig, is waking up on another processor.  This
1309 	 * condition can lead to overlapping accesses to the VGA range
1310 	 * and the framebuffer (causing system lockups).
1311 	 *
1312 	 * To account for this we duplicate this code below only if the
1313 	 * controlling process is gone and we've called reset_vc.
1314 	 */
1315 	if (old_vc_mode != vc->vc_mode) {
1316 		if (vc->vc_mode == KD_TEXT)
1317 			do_unblank_screen(1);
1318 		else
1319 			do_blank_screen(1);
1320 	}
1321 
1322 	/*
1323 	 * If this new console is under process control, send it a signal
1324 	 * telling it that it has acquired. Also check if it has died and
1325 	 * clean up (similar to logic employed in change_console())
1326 	 */
1327 	if (vc->vt_mode.mode == VT_PROCESS) {
1328 		/*
1329 		 * Send the signal as privileged - kill_pid() will
1330 		 * tell us if the process has gone or something else
1331 		 * is awry
1332 		 */
1333 		if (kill_pid(vc->vt_pid, vc->vt_mode.acqsig, 1) != 0) {
1334 		/*
1335 		 * The controlling process has died, so we revert back to
1336 		 * normal operation. In this case, we'll also change back
1337 		 * to KD_TEXT mode. I'm not sure if this is strictly correct
1338 		 * but it saves the agony when the X server dies and the screen
1339 		 * remains blanked due to KD_GRAPHICS! It would be nice to do
1340 		 * this outside of VT_PROCESS but there is no single process
1341 		 * to account for and tracking tty count may be undesirable.
1342 		 */
1343 			reset_vc(vc);
1344 
1345 			if (old_vc_mode != vc->vc_mode) {
1346 				if (vc->vc_mode == KD_TEXT)
1347 					do_unblank_screen(1);
1348 				else
1349 					do_blank_screen(1);
1350 			}
1351 		}
1352 	}
1353 
1354 	/*
1355 	 * Wake anyone waiting for their VT to activate
1356 	 */
1357 	vt_event_post(VT_EVENT_SWITCH, old, vc->vc_num);
1358 	return;
1359 }
1360 
1361 /*
1362  * Performs the front-end of a vt switch
1363  */
1364 void change_console(struct vc_data *new_vc)
1365 {
1366 	struct vc_data *vc;
1367 
1368 	if (!new_vc || new_vc->vc_num == fg_console || vt_dont_switch)
1369 		return;
1370 
1371 	/*
1372 	 * If this vt is in process mode, then we need to handshake with
1373 	 * that process before switching. Essentially, we store where that
1374 	 * vt wants to switch to and wait for it to tell us when it's done
1375 	 * (via VT_RELDISP ioctl).
1376 	 *
1377 	 * We also check to see if the controlling process still exists.
1378 	 * If it doesn't, we reset this vt to auto mode and continue.
1379 	 * This is a cheap way to track process control. The worst thing
1380 	 * that can happen is: we send a signal to a process, it dies, and
1381 	 * the switch gets "lost" waiting for a response; hopefully, the
1382 	 * user will try again, we'll detect the process is gone (unless
1383 	 * the user waits just the right amount of time :-) and revert the
1384 	 * vt to auto control.
1385 	 */
1386 	vc = vc_cons[fg_console].d;
1387 	if (vc->vt_mode.mode == VT_PROCESS) {
1388 		/*
1389 		 * Send the signal as privileged - kill_pid() will
1390 		 * tell us if the process has gone or something else
1391 		 * is awry.
1392 		 *
1393 		 * We need to set vt_newvt *before* sending the signal or we
1394 		 * have a race.
1395 		 */
1396 		vc->vt_newvt = new_vc->vc_num;
1397 		if (kill_pid(vc->vt_pid, vc->vt_mode.relsig, 1) == 0) {
1398 			/*
1399 			 * It worked. Mark the vt to switch to and
1400 			 * return. The process needs to send us a
1401 			 * VT_RELDISP ioctl to complete the switch.
1402 			 */
1403 			return;
1404 		}
1405 
1406 		/*
1407 		 * The controlling process has died, so we revert back to
1408 		 * normal operation. In this case, we'll also change back
1409 		 * to KD_TEXT mode. I'm not sure if this is strictly correct
1410 		 * but it saves the agony when the X server dies and the screen
1411 		 * remains blanked due to KD_GRAPHICS! It would be nice to do
1412 		 * this outside of VT_PROCESS but there is no single process
1413 		 * to account for and tracking tty count may be undesirable.
1414 		 */
1415 		reset_vc(vc);
1416 
1417 		/*
1418 		 * Fall through to normal (VT_AUTO) handling of the switch...
1419 		 */
1420 	}
1421 
1422 	/*
1423 	 * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
1424 	 */
1425 	if (vc->vc_mode == KD_GRAPHICS)
1426 		return;
1427 
1428 	complete_change_console(new_vc);
1429 }
1430 
1431 /* Perform a kernel triggered VT switch for suspend/resume */
1432 
1433 static int disable_vt_switch;
1434 
1435 int vt_move_to_console(unsigned int vt, int alloc)
1436 {
1437 	int prev;
1438 
1439 	console_lock();
1440 	/* Graphics mode - up to X */
1441 	if (disable_vt_switch) {
1442 		console_unlock();
1443 		return 0;
1444 	}
1445 	prev = fg_console;
1446 
1447 	if (alloc && vc_allocate(vt)) {
1448 		/* we can't have a free VC for now. Too bad,
1449 		 * we don't want to mess the screen for now. */
1450 		console_unlock();
1451 		return -ENOSPC;
1452 	}
1453 
1454 	if (set_console(vt)) {
1455 		/*
1456 		 * We're unable to switch to the SUSPEND_CONSOLE.
1457 		 * Let the calling function know so it can decide
1458 		 * what to do.
1459 		 */
1460 		console_unlock();
1461 		return -EIO;
1462 	}
1463 	console_unlock();
1464 	if (vt_waitactive(vt + 1)) {
1465 		pr_debug("Suspend: Can't switch VCs.");
1466 		return -EINTR;
1467 	}
1468 	return prev;
1469 }
1470 
1471 /*
1472  * Normally during a suspend, we allocate a new console and switch to it.
1473  * When we resume, we switch back to the original console.  This switch
1474  * can be slow, so on systems where the framebuffer can handle restoration
1475  * of video registers anyways, there's little point in doing the console
1476  * switch.  This function allows you to disable it by passing it '0'.
1477  */
1478 void pm_set_vt_switch(int do_switch)
1479 {
1480 	console_lock();
1481 	disable_vt_switch = !do_switch;
1482 	console_unlock();
1483 }
1484 EXPORT_SYMBOL(pm_set_vt_switch);
1485