xref: /openbmc/linux/drivers/tty/vt/vc_screen.c (revision 8fb9ea65)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Provide access to virtual console memory.
4  * /dev/vcs: the screen as it is being viewed right now (possibly scrolled)
5  * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
6  *            [minor: N]
7  *
8  * /dev/vcsaN: idem, but including attributes, and prefixed with
9  *	the 4 bytes lines,columns,x,y (as screendump used to give).
10  *	Attribute/character pair is in native endianity.
11  *            [minor: N+128]
12  *
13  * /dev/vcsuN: similar to /dev/vcsaN but using 4-byte unicode values
14  *	instead of 1-byte screen glyph values.
15  *            [minor: N+64]
16  *
17  * /dev/vcsuaN: same idea as /dev/vcsaN for unicode (not yet implemented).
18  *
19  * This replaces screendump and part of selection, so that the system
20  * administrator can control access using file system permissions.
21  *
22  * aeb@cwi.nl - efter Friedas begravelse - 950211
23  *
24  * machek@k332.feld.cvut.cz - modified not to send characters to wrong console
25  *	 - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
26  *	 - making it shorter - scr_readw are macros which expand in PRETTY long code
27  */
28 
29 #include <linux/kernel.h>
30 #include <linux/major.h>
31 #include <linux/errno.h>
32 #include <linux/export.h>
33 #include <linux/tty.h>
34 #include <linux/interrupt.h>
35 #include <linux/mm.h>
36 #include <linux/init.h>
37 #include <linux/vt_kern.h>
38 #include <linux/selection.h>
39 #include <linux/kbd_kern.h>
40 #include <linux/console.h>
41 #include <linux/device.h>
42 #include <linux/sched.h>
43 #include <linux/fs.h>
44 #include <linux/poll.h>
45 #include <linux/signal.h>
46 #include <linux/slab.h>
47 #include <linux/notifier.h>
48 
49 #include <linux/uaccess.h>
50 #include <asm/byteorder.h>
51 #include <asm/unaligned.h>
52 
53 #define HEADER_SIZE	4u
54 #define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
55 
56 /*
57  * Our minor space:
58  *
59  *   0 ... 63	glyph mode without attributes
60  *  64 ... 127	unicode mode without attributes
61  * 128 ... 191	glyph mode with attributes
62  * 192 ... 255	unused (reserved for unicode with attributes)
63  *
64  * This relies on MAX_NR_CONSOLES being  <= 63, meaning 63 actual consoles
65  * with minors 0, 64, 128 and 192 being proxies for the foreground console.
66  */
67 #if MAX_NR_CONSOLES > 63
68 #warning "/dev/vcs* devices may not accommodate more than 63 consoles"
69 #endif
70 
71 #define console(inode)		(iminor(inode) & 63)
72 #define use_unicode(inode)	(iminor(inode) & 64)
73 #define use_attributes(inode)	(iminor(inode) & 128)
74 
75 
76 struct vcs_poll_data {
77 	struct notifier_block notifier;
78 	unsigned int cons_num;
79 	int event;
80 	wait_queue_head_t waitq;
81 	struct fasync_struct *fasync;
82 };
83 
84 static int
vcs_notifier(struct notifier_block * nb,unsigned long code,void * _param)85 vcs_notifier(struct notifier_block *nb, unsigned long code, void *_param)
86 {
87 	struct vt_notifier_param *param = _param;
88 	struct vc_data *vc = param->vc;
89 	struct vcs_poll_data *poll =
90 		container_of(nb, struct vcs_poll_data, notifier);
91 	int currcons = poll->cons_num;
92 	int fa_band;
93 
94 	switch (code) {
95 	case VT_UPDATE:
96 		fa_band = POLL_PRI;
97 		break;
98 	case VT_DEALLOCATE:
99 		fa_band = POLL_HUP;
100 		break;
101 	default:
102 		return NOTIFY_DONE;
103 	}
104 
105 	if (currcons == 0)
106 		currcons = fg_console;
107 	else
108 		currcons--;
109 	if (currcons != vc->vc_num)
110 		return NOTIFY_DONE;
111 
112 	poll->event = code;
113 	wake_up_interruptible(&poll->waitq);
114 	kill_fasync(&poll->fasync, SIGIO, fa_band);
115 	return NOTIFY_OK;
116 }
117 
118 static void
vcs_poll_data_free(struct vcs_poll_data * poll)119 vcs_poll_data_free(struct vcs_poll_data *poll)
120 {
121 	unregister_vt_notifier(&poll->notifier);
122 	kfree(poll);
123 }
124 
125 static struct vcs_poll_data *
vcs_poll_data_get(struct file * file)126 vcs_poll_data_get(struct file *file)
127 {
128 	struct vcs_poll_data *poll = file->private_data, *kill = NULL;
129 
130 	if (poll)
131 		return poll;
132 
133 	poll = kzalloc(sizeof(*poll), GFP_KERNEL);
134 	if (!poll)
135 		return NULL;
136 	poll->cons_num = console(file_inode(file));
137 	init_waitqueue_head(&poll->waitq);
138 	poll->notifier.notifier_call = vcs_notifier;
139 	/*
140 	 * In order not to lose any update event, we must pretend one might
141 	 * have occurred before we have a chance to register our notifier.
142 	 * This is also how user space has come to detect which kernels
143 	 * support POLLPRI on /dev/vcs* devices i.e. using poll() with
144 	 * POLLPRI and a zero timeout.
145 	 */
146 	poll->event = VT_UPDATE;
147 
148 	if (register_vt_notifier(&poll->notifier) != 0) {
149 		kfree(poll);
150 		return NULL;
151 	}
152 
153 	/*
154 	 * This code may be called either through ->poll() or ->fasync().
155 	 * If we have two threads using the same file descriptor, they could
156 	 * both enter this function, both notice that the structure hasn't
157 	 * been allocated yet and go ahead allocating it in parallel, but
158 	 * only one of them must survive and be shared otherwise we'd leak
159 	 * memory with a dangling notifier callback.
160 	 */
161 	spin_lock(&file->f_lock);
162 	if (!file->private_data) {
163 		file->private_data = poll;
164 	} else {
165 		/* someone else raced ahead of us */
166 		kill = poll;
167 		poll = file->private_data;
168 	}
169 	spin_unlock(&file->f_lock);
170 	if (kill)
171 		vcs_poll_data_free(kill);
172 
173 	return poll;
174 }
175 
176 /**
177  * vcs_vc -- return VC for @inode
178  * @inode: inode for which to return a VC
179  * @viewed: returns whether this console is currently foreground (viewed)
180  *
181  * Must be called with console_lock.
182  */
vcs_vc(struct inode * inode,bool * viewed)183 static struct vc_data *vcs_vc(struct inode *inode, bool *viewed)
184 {
185 	unsigned int currcons = console(inode);
186 
187 	WARN_CONSOLE_UNLOCKED();
188 
189 	if (currcons == 0) {
190 		currcons = fg_console;
191 		if (viewed)
192 			*viewed = true;
193 	} else {
194 		currcons--;
195 		if (viewed)
196 			*viewed = false;
197 	}
198 	return vc_cons[currcons].d;
199 }
200 
201 /**
202  * vcs_size -- return size for a VC in @vc
203  * @vc: which VC
204  * @attr: does it use attributes?
205  * @unicode: is it unicode?
206  *
207  * Must be called with console_lock.
208  */
vcs_size(const struct vc_data * vc,bool attr,bool unicode)209 static int vcs_size(const struct vc_data *vc, bool attr, bool unicode)
210 {
211 	int size;
212 
213 	WARN_CONSOLE_UNLOCKED();
214 
215 	size = vc->vc_rows * vc->vc_cols;
216 
217 	if (attr) {
218 		if (unicode)
219 			return -EOPNOTSUPP;
220 
221 		size = 2 * size + HEADER_SIZE;
222 	} else if (unicode)
223 		size *= 4;
224 
225 	return size;
226 }
227 
vcs_lseek(struct file * file,loff_t offset,int orig)228 static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
229 {
230 	struct inode *inode = file_inode(file);
231 	struct vc_data *vc;
232 	int size;
233 
234 	console_lock();
235 	vc = vcs_vc(inode, NULL);
236 	if (!vc) {
237 		console_unlock();
238 		return -ENXIO;
239 	}
240 
241 	size = vcs_size(vc, use_attributes(inode), use_unicode(inode));
242 	console_unlock();
243 	if (size < 0)
244 		return size;
245 	return fixed_size_llseek(file, offset, orig, size);
246 }
247 
vcs_read_buf_uni(struct vc_data * vc,char * con_buf,unsigned int pos,unsigned int count,bool viewed)248 static int vcs_read_buf_uni(struct vc_data *vc, char *con_buf,
249 		unsigned int pos, unsigned int count, bool viewed)
250 {
251 	unsigned int nr, row, col, maxcol = vc->vc_cols;
252 	int ret;
253 
254 	ret = vc_uniscr_check(vc);
255 	if (ret)
256 		return ret;
257 
258 	pos /= 4;
259 	row = pos / maxcol;
260 	col = pos % maxcol;
261 	nr = maxcol - col;
262 	do {
263 		if (nr > count / 4)
264 			nr = count / 4;
265 		vc_uniscr_copy_line(vc, con_buf, viewed, row, col, nr);
266 		con_buf += nr * 4;
267 		count -= nr * 4;
268 		row++;
269 		col = 0;
270 		nr = maxcol;
271 	} while (count);
272 
273 	return 0;
274 }
275 
vcs_read_buf_noattr(const struct vc_data * vc,char * con_buf,unsigned int pos,unsigned int count,bool viewed)276 static void vcs_read_buf_noattr(const struct vc_data *vc, char *con_buf,
277 		unsigned int pos, unsigned int count, bool viewed)
278 {
279 	u16 *org;
280 	unsigned int col, maxcol = vc->vc_cols;
281 
282 	org = screen_pos(vc, pos, viewed);
283 	col = pos % maxcol;
284 	pos += maxcol - col;
285 
286 	while (count-- > 0) {
287 		*con_buf++ = (vcs_scr_readw(vc, org++) & 0xff);
288 		if (++col == maxcol) {
289 			org = screen_pos(vc, pos, viewed);
290 			col = 0;
291 			pos += maxcol;
292 		}
293 	}
294 }
295 
vcs_read_buf(const struct vc_data * vc,char * con_buf,unsigned int pos,unsigned int count,bool viewed,unsigned int * skip)296 static unsigned int vcs_read_buf(const struct vc_data *vc, char *con_buf,
297 		unsigned int pos, unsigned int count, bool viewed,
298 		unsigned int *skip)
299 {
300 	u16 *org, *con_buf16;
301 	unsigned int col, maxcol = vc->vc_cols;
302 	unsigned int filled = count;
303 
304 	if (pos < HEADER_SIZE) {
305 		/* clamp header values if they don't fit */
306 		con_buf[0] = min(vc->vc_rows, 0xFFu);
307 		con_buf[1] = min(vc->vc_cols, 0xFFu);
308 		getconsxy(vc, con_buf + 2);
309 
310 		*skip += pos;
311 		count += pos;
312 		if (count > CON_BUF_SIZE) {
313 			count = CON_BUF_SIZE;
314 			filled = count - pos;
315 		}
316 
317 		/* Advance state pointers and move on. */
318 		count -= min(HEADER_SIZE, count);
319 		pos = HEADER_SIZE;
320 		con_buf += HEADER_SIZE;
321 		/* If count >= 0, then pos is even... */
322 	} else if (pos & 1) {
323 		/*
324 		 * Skip first byte for output if start address is odd. Update
325 		 * region sizes up/down depending on free space in buffer.
326 		 */
327 		(*skip)++;
328 		if (count < CON_BUF_SIZE)
329 			count++;
330 		else
331 			filled--;
332 	}
333 
334 	if (!count)
335 		return filled;
336 
337 	pos -= HEADER_SIZE;
338 	pos /= 2;
339 	col = pos % maxcol;
340 
341 	org = screen_pos(vc, pos, viewed);
342 	pos += maxcol - col;
343 
344 	/*
345 	 * Buffer has even length, so we can always copy character + attribute.
346 	 * We do not copy last byte to userspace if count is odd.
347 	 */
348 	count = (count + 1) / 2;
349 	con_buf16 = (u16 *)con_buf;
350 
351 	while (count) {
352 		*con_buf16++ = vcs_scr_readw(vc, org++);
353 		count--;
354 		if (++col == maxcol) {
355 			org = screen_pos(vc, pos, viewed);
356 			col = 0;
357 			pos += maxcol;
358 		}
359 	}
360 
361 	return filled;
362 }
363 
364 static ssize_t
vcs_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)365 vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
366 {
367 	struct inode *inode = file_inode(file);
368 	struct vc_data *vc;
369 	struct vcs_poll_data *poll;
370 	unsigned int read;
371 	ssize_t ret;
372 	char *con_buf;
373 	loff_t pos;
374 	bool viewed, attr, uni_mode;
375 
376 	con_buf = (char *) __get_free_page(GFP_KERNEL);
377 	if (!con_buf)
378 		return -ENOMEM;
379 
380 	pos = *ppos;
381 
382 	/* Select the proper current console and verify
383 	 * sanity of the situation under the console lock.
384 	 */
385 	console_lock();
386 
387 	uni_mode = use_unicode(inode);
388 	attr = use_attributes(inode);
389 
390 	ret = -EINVAL;
391 	if (pos < 0)
392 		goto unlock_out;
393 	/* we enforce 32-bit alignment for pos and count in unicode mode */
394 	if (uni_mode && (pos | count) & 3)
395 		goto unlock_out;
396 
397 	poll = file->private_data;
398 	if (count && poll)
399 		poll->event = 0;
400 	read = 0;
401 	ret = 0;
402 	while (count) {
403 		unsigned int this_round, skip = 0;
404 		int size;
405 
406 		vc = vcs_vc(inode, &viewed);
407 		if (!vc) {
408 			ret = -ENXIO;
409 			break;
410 		}
411 
412 		/* Check whether we are above size each round,
413 		 * as copy_to_user at the end of this loop
414 		 * could sleep.
415 		 */
416 		size = vcs_size(vc, attr, uni_mode);
417 		if (size < 0) {
418 			ret = size;
419 			break;
420 		}
421 		if (pos >= size)
422 			break;
423 		if (count > size - pos)
424 			count = size - pos;
425 
426 		this_round = count;
427 		if (this_round > CON_BUF_SIZE)
428 			this_round = CON_BUF_SIZE;
429 
430 		/* Perform the whole read into the local con_buf.
431 		 * Then we can drop the console spinlock and safely
432 		 * attempt to move it to userspace.
433 		 */
434 
435 		if (uni_mode) {
436 			ret = vcs_read_buf_uni(vc, con_buf, pos, this_round,
437 					viewed);
438 			if (ret)
439 				break;
440 		} else if (!attr) {
441 			vcs_read_buf_noattr(vc, con_buf, pos, this_round,
442 					viewed);
443 		} else {
444 			this_round = vcs_read_buf(vc, con_buf, pos, this_round,
445 					viewed, &skip);
446 		}
447 
448 		/* Finally, release the console semaphore while we push
449 		 * all the data to userspace from our temporary buffer.
450 		 *
451 		 * AKPM: Even though it's a semaphore, we should drop it because
452 		 * the pagefault handling code may want to call printk().
453 		 */
454 
455 		console_unlock();
456 		ret = copy_to_user(buf, con_buf + skip, this_round);
457 		console_lock();
458 
459 		if (ret) {
460 			read += this_round - ret;
461 			ret = -EFAULT;
462 			break;
463 		}
464 		buf += this_round;
465 		pos += this_round;
466 		read += this_round;
467 		count -= this_round;
468 	}
469 	*ppos += read;
470 	if (read)
471 		ret = read;
472 unlock_out:
473 	console_unlock();
474 	free_page((unsigned long) con_buf);
475 	return ret;
476 }
477 
vcs_write_buf_noattr(struct vc_data * vc,const char * con_buf,unsigned int pos,unsigned int count,bool viewed,u16 ** org0)478 static u16 *vcs_write_buf_noattr(struct vc_data *vc, const char *con_buf,
479 		unsigned int pos, unsigned int count, bool viewed, u16 **org0)
480 {
481 	u16 *org;
482 	unsigned int col, maxcol = vc->vc_cols;
483 
484 	*org0 = org = screen_pos(vc, pos, viewed);
485 	col = pos % maxcol;
486 	pos += maxcol - col;
487 
488 	while (count > 0) {
489 		unsigned char c = *con_buf++;
490 
491 		count--;
492 		vcs_scr_writew(vc,
493 			       (vcs_scr_readw(vc, org) & 0xff00) | c, org);
494 		org++;
495 		if (++col == maxcol) {
496 			org = screen_pos(vc, pos, viewed);
497 			col = 0;
498 			pos += maxcol;
499 		}
500 	}
501 
502 	return org;
503 }
504 
505 /*
506  * Compilers (gcc 10) are unable to optimize the swap in cpu_to_le16. So do it
507  * the poor man way.
508  */
vc_compile_le16(u8 hi,u8 lo)509 static inline u16 vc_compile_le16(u8 hi, u8 lo)
510 {
511 #ifdef __BIG_ENDIAN
512 	return (lo << 8u) | hi;
513 #else
514 	return (hi << 8u) | lo;
515 #endif
516 }
517 
vcs_write_buf(struct vc_data * vc,const char * con_buf,unsigned int pos,unsigned int count,bool viewed,u16 ** org0)518 static u16 *vcs_write_buf(struct vc_data *vc, const char *con_buf,
519 		unsigned int pos, unsigned int count, bool viewed, u16 **org0)
520 {
521 	u16 *org;
522 	unsigned int col, maxcol = vc->vc_cols;
523 	unsigned char c;
524 
525 	/* header */
526 	if (pos < HEADER_SIZE) {
527 		char header[HEADER_SIZE];
528 
529 		getconsxy(vc, header + 2);
530 		while (pos < HEADER_SIZE && count > 0) {
531 			count--;
532 			header[pos++] = *con_buf++;
533 		}
534 		if (!viewed)
535 			putconsxy(vc, header + 2);
536 	}
537 
538 	if (!count)
539 		return NULL;
540 
541 	pos -= HEADER_SIZE;
542 	col = (pos/2) % maxcol;
543 
544 	*org0 = org = screen_pos(vc, pos/2, viewed);
545 
546 	/* odd pos -- the first single character */
547 	if (pos & 1) {
548 		count--;
549 		c = *con_buf++;
550 		vcs_scr_writew(vc, vc_compile_le16(c, vcs_scr_readw(vc, org)),
551 				org);
552 		org++;
553 		pos++;
554 		if (++col == maxcol) {
555 			org = screen_pos(vc, pos/2, viewed);
556 			col = 0;
557 		}
558 	}
559 
560 	pos /= 2;
561 	pos += maxcol - col;
562 
563 	/* even pos -- handle attr+character pairs */
564 	while (count > 1) {
565 		unsigned short w;
566 
567 		w = get_unaligned(((unsigned short *)con_buf));
568 		vcs_scr_writew(vc, w, org++);
569 		con_buf += 2;
570 		count -= 2;
571 		if (++col == maxcol) {
572 			org = screen_pos(vc, pos, viewed);
573 			col = 0;
574 			pos += maxcol;
575 		}
576 	}
577 
578 	if (!count)
579 		return org;
580 
581 	/* odd pos -- the remaining character */
582 	c = *con_buf++;
583 	vcs_scr_writew(vc, vc_compile_le16(vcs_scr_readw(vc, org) >> 8, c),
584 				org);
585 
586 	return org;
587 }
588 
589 static ssize_t
vcs_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)590 vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
591 {
592 	struct inode *inode = file_inode(file);
593 	struct vc_data *vc;
594 	char *con_buf;
595 	u16 *org0, *org;
596 	unsigned int written;
597 	int size;
598 	ssize_t ret;
599 	loff_t pos;
600 	bool viewed, attr;
601 
602 	if (use_unicode(inode))
603 		return -EOPNOTSUPP;
604 
605 	con_buf = (char *) __get_free_page(GFP_KERNEL);
606 	if (!con_buf)
607 		return -ENOMEM;
608 
609 	pos = *ppos;
610 
611 	/* Select the proper current console and verify
612 	 * sanity of the situation under the console lock.
613 	 */
614 	console_lock();
615 
616 	attr = use_attributes(inode);
617 	ret = -ENXIO;
618 	vc = vcs_vc(inode, &viewed);
619 	if (!vc)
620 		goto unlock_out;
621 
622 	size = vcs_size(vc, attr, false);
623 	if (size < 0) {
624 		ret = size;
625 		goto unlock_out;
626 	}
627 	ret = -EINVAL;
628 	if (pos < 0 || pos > size)
629 		goto unlock_out;
630 	if (count > size - pos)
631 		count = size - pos;
632 	written = 0;
633 	while (count) {
634 		unsigned int this_round = count;
635 
636 		if (this_round > CON_BUF_SIZE)
637 			this_round = CON_BUF_SIZE;
638 
639 		/* Temporarily drop the console lock so that we can read
640 		 * in the write data from userspace safely.
641 		 */
642 		console_unlock();
643 		ret = copy_from_user(con_buf, buf, this_round);
644 		console_lock();
645 
646 		if (ret) {
647 			this_round -= ret;
648 			if (!this_round) {
649 				/* Abort loop if no data were copied. Otherwise
650 				 * fail with -EFAULT.
651 				 */
652 				if (written)
653 					break;
654 				ret = -EFAULT;
655 				goto unlock_out;
656 			}
657 		}
658 
659 		/* The vc might have been freed or vcs_size might have changed
660 		 * while we slept to grab the user buffer, so recheck.
661 		 * Return data written up to now on failure.
662 		 */
663 		vc = vcs_vc(inode, &viewed);
664 		if (!vc) {
665 			if (written)
666 				break;
667 			ret = -ENXIO;
668 			goto unlock_out;
669 		}
670 		size = vcs_size(vc, attr, false);
671 		if (size < 0) {
672 			if (written)
673 				break;
674 			ret = size;
675 			goto unlock_out;
676 		}
677 		if (pos >= size)
678 			break;
679 		if (this_round > size - pos)
680 			this_round = size - pos;
681 
682 		/* OK, now actually push the write to the console
683 		 * under the lock using the local kernel buffer.
684 		 */
685 
686 		if (attr)
687 			org = vcs_write_buf(vc, con_buf, pos, this_round,
688 					viewed, &org0);
689 		else
690 			org = vcs_write_buf_noattr(vc, con_buf, pos, this_round,
691 					viewed, &org0);
692 
693 		count -= this_round;
694 		written += this_round;
695 		buf += this_round;
696 		pos += this_round;
697 		if (org)
698 			update_region(vc, (unsigned long)(org0), org - org0);
699 	}
700 	*ppos += written;
701 	ret = written;
702 	if (written)
703 		vcs_scr_updated(vc);
704 
705 unlock_out:
706 	console_unlock();
707 	free_page((unsigned long) con_buf);
708 	return ret;
709 }
710 
711 static __poll_t
vcs_poll(struct file * file,poll_table * wait)712 vcs_poll(struct file *file, poll_table *wait)
713 {
714 	struct vcs_poll_data *poll = vcs_poll_data_get(file);
715 	__poll_t ret = DEFAULT_POLLMASK|EPOLLERR;
716 
717 	if (poll) {
718 		poll_wait(file, &poll->waitq, wait);
719 		switch (poll->event) {
720 		case VT_UPDATE:
721 			ret = DEFAULT_POLLMASK|EPOLLPRI;
722 			break;
723 		case VT_DEALLOCATE:
724 			ret = DEFAULT_POLLMASK|EPOLLHUP|EPOLLERR;
725 			break;
726 		case 0:
727 			ret = DEFAULT_POLLMASK;
728 			break;
729 		}
730 	}
731 	return ret;
732 }
733 
734 static int
vcs_fasync(int fd,struct file * file,int on)735 vcs_fasync(int fd, struct file *file, int on)
736 {
737 	struct vcs_poll_data *poll = file->private_data;
738 
739 	if (!poll) {
740 		/* don't allocate anything if all we want is disable fasync */
741 		if (!on)
742 			return 0;
743 		poll = vcs_poll_data_get(file);
744 		if (!poll)
745 			return -ENOMEM;
746 	}
747 
748 	return fasync_helper(fd, file, on, &poll->fasync);
749 }
750 
751 static int
vcs_open(struct inode * inode,struct file * filp)752 vcs_open(struct inode *inode, struct file *filp)
753 {
754 	unsigned int currcons = console(inode);
755 	bool attr = use_attributes(inode);
756 	bool uni_mode = use_unicode(inode);
757 	int ret = 0;
758 
759 	/* we currently don't support attributes in unicode mode */
760 	if (attr && uni_mode)
761 		return -EOPNOTSUPP;
762 
763 	console_lock();
764 	if(currcons && !vc_cons_allocated(currcons-1))
765 		ret = -ENXIO;
766 	console_unlock();
767 	return ret;
768 }
769 
vcs_release(struct inode * inode,struct file * file)770 static int vcs_release(struct inode *inode, struct file *file)
771 {
772 	struct vcs_poll_data *poll = file->private_data;
773 
774 	if (poll)
775 		vcs_poll_data_free(poll);
776 	return 0;
777 }
778 
779 static const struct file_operations vcs_fops = {
780 	.llseek		= vcs_lseek,
781 	.read		= vcs_read,
782 	.write		= vcs_write,
783 	.poll		= vcs_poll,
784 	.fasync		= vcs_fasync,
785 	.open		= vcs_open,
786 	.release	= vcs_release,
787 };
788 
789 static struct class *vc_class;
790 
vcs_make_sysfs(int index)791 void vcs_make_sysfs(int index)
792 {
793 	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
794 		      "vcs%u", index + 1);
795 	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 65), NULL,
796 		      "vcsu%u", index + 1);
797 	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
798 		      "vcsa%u", index + 1);
799 }
800 
vcs_remove_sysfs(int index)801 void vcs_remove_sysfs(int index)
802 {
803 	device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
804 	device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 65));
805 	device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
806 }
807 
vcs_init(void)808 int __init vcs_init(void)
809 {
810 	unsigned int i;
811 
812 	if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
813 		panic("unable to get major %d for vcs device", VCS_MAJOR);
814 	vc_class = class_create("vc");
815 
816 	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
817 	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 64), NULL, "vcsu");
818 	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
819 	for (i = 0; i < MIN_NR_CONSOLES; i++)
820 		vcs_make_sysfs(i);
821 	return 0;
822 }
823