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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#undef attr
54#undef org
55#undef addr
56#define HEADER_SIZE 4
57
58#define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
59
60/*
61 * Our minor space:
62 *
63 * 0 ... 63 glyph mode without attributes
64 * 64 ... 127 unicode mode without attributes
65 * 128 ... 191 glyph mode with attributes
66 * 192 ... 255 unused (reserved for unicode with attributes)
67 *
68 * This relies on MAX_NR_CONSOLES being <= 63, meaning 63 actual consoles
69 * with minors 0, 64, 128 and 192 being proxies for the foreground console.
70 */
71#if MAX_NR_CONSOLES > 63
72#warning "/dev/vcs* devices may not accommodate more than 63 consoles"
73#endif
74
75#define console(inode) (iminor(inode) & 63)
76#define use_unicode(inode) (iminor(inode) & 64)
77#define use_attributes(inode) (iminor(inode) & 128)
78
79
80struct vcs_poll_data {
81 struct notifier_block notifier;
82 unsigned int cons_num;
83 int event;
84 wait_queue_head_t waitq;
85 struct fasync_struct *fasync;
86};
87
88static int
89vcs_notifier(struct notifier_block *nb, unsigned long code, void *_param)
90{
91 struct vt_notifier_param *param = _param;
92 struct vc_data *vc = param->vc;
93 struct vcs_poll_data *poll =
94 container_of(nb, struct vcs_poll_data, notifier);
95 int currcons = poll->cons_num;
96 int fa_band;
97
98 switch (code) {
99 case VT_UPDATE:
100 fa_band = POLL_PRI;
101 break;
102 case VT_DEALLOCATE:
103 fa_band = POLL_HUP;
104 break;
105 default:
106 return NOTIFY_DONE;
107 }
108
109 if (currcons == 0)
110 currcons = fg_console;
111 else
112 currcons--;
113 if (currcons != vc->vc_num)
114 return NOTIFY_DONE;
115
116 poll->event = code;
117 wake_up_interruptible(&poll->waitq);
118 kill_fasync(&poll->fasync, SIGIO, fa_band);
119 return NOTIFY_OK;
120}
121
122static void
123vcs_poll_data_free(struct vcs_poll_data *poll)
124{
125 unregister_vt_notifier(&poll->notifier);
126 kfree(poll);
127}
128
129static struct vcs_poll_data *
130vcs_poll_data_get(struct file *file)
131{
132 struct vcs_poll_data *poll = file->private_data, *kill = NULL;
133
134 if (poll)
135 return poll;
136
137 poll = kzalloc(sizeof(*poll), GFP_KERNEL);
138 if (!poll)
139 return NULL;
140 poll->cons_num = console(file_inode(file));
141 init_waitqueue_head(&poll->waitq);
142 poll->notifier.notifier_call = vcs_notifier;
143 /*
144 * In order not to lose any update event, we must pretend one might
145 * have occurred before we have a chance to register our notifier.
146 * This is also how user space has come to detect which kernels
147 * support POLLPRI on /dev/vcs* devices i.e. using poll() with
148 * POLLPRI and a zero timeout.
149 */
150 poll->event = VT_UPDATE;
151
152 if (register_vt_notifier(&poll->notifier) != 0) {
153 kfree(poll);
154 return NULL;
155 }
156
157 /*
158 * This code may be called either through ->poll() or ->fasync().
159 * If we have two threads using the same file descriptor, they could
160 * both enter this function, both notice that the structure hasn't
161 * been allocated yet and go ahead allocating it in parallel, but
162 * only one of them must survive and be shared otherwise we'd leak
163 * memory with a dangling notifier callback.
164 */
165 spin_lock(&file->f_lock);
166 if (!file->private_data) {
167 file->private_data = poll;
168 } else {
169 /* someone else raced ahead of us */
170 kill = poll;
171 poll = file->private_data;
172 }
173 spin_unlock(&file->f_lock);
174 if (kill)
175 vcs_poll_data_free(kill);
176
177 return poll;
178}
179
180/*
181 * Returns VC for inode.
182 * Must be called with console_lock.
183 */
184static struct vc_data*
185vcs_vc(struct inode *inode, int *viewed)
186{
187 unsigned int currcons = console(inode);
188
189 WARN_CONSOLE_UNLOCKED();
190
191 if (currcons == 0) {
192 currcons = fg_console;
193 if (viewed)
194 *viewed = 1;
195 } else {
196 currcons--;
197 if (viewed)
198 *viewed = 0;
199 }
200 return vc_cons[currcons].d;
201}
202
203/*
204 * Returns size for VC carried by inode.
205 * Must be called with console_lock.
206 */
207static int
208vcs_size(struct inode *inode)
209{
210 int size;
211 struct vc_data *vc;
212
213 WARN_CONSOLE_UNLOCKED();
214
215 vc = vcs_vc(inode, NULL);
216 if (!vc)
217 return -ENXIO;
218
219 size = vc->vc_rows * vc->vc_cols;
220
221 if (use_attributes(inode)) {
222 if (use_unicode(inode))
223 return -EOPNOTSUPP;
224 size = 2*size + HEADER_SIZE;
225 } else if (use_unicode(inode))
226 size *= 4;
227 return size;
228}
229
230static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
231{
232 int size;
233
234 console_lock();
235 size = vcs_size(file_inode(file));
236 console_unlock();
237 if (size < 0)
238 return size;
239 return fixed_size_llseek(file, offset, orig, size);
240}
241
242
243static ssize_t
244vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
245{
246 struct inode *inode = file_inode(file);
247 struct vc_data *vc;
248 struct vcs_poll_data *poll;
249 long pos, read;
250 int attr, uni_mode, row, col, maxcol, viewed;
251 unsigned short *org = NULL;
252 ssize_t ret;
253 char *con_buf;
254
255 con_buf = (char *) __get_free_page(GFP_KERNEL);
256 if (!con_buf)
257 return -ENOMEM;
258
259 pos = *ppos;
260
261 /* Select the proper current console and verify
262 * sanity of the situation under the console lock.
263 */
264 console_lock();
265
266 uni_mode = use_unicode(inode);
267 attr = use_attributes(inode);
268 ret = -ENXIO;
269 vc = vcs_vc(inode, &viewed);
270 if (!vc)
271 goto unlock_out;
272
273 ret = -EINVAL;
274 if (pos < 0)
275 goto unlock_out;
276 /* we enforce 32-bit alignment for pos and count in unicode mode */
277 if (uni_mode && (pos | count) & 3)
278 goto unlock_out;
279
280 poll = file->private_data;
281 if (count && poll)
282 poll->event = 0;
283 read = 0;
284 ret = 0;
285 while (count) {
286 char *con_buf0, *con_buf_start;
287 long this_round, size;
288 ssize_t orig_count;
289 long p = pos;
290
291 /* Check whether we are above size each round,
292 * as copy_to_user at the end of this loop
293 * could sleep.
294 */
295 size = vcs_size(inode);
296 if (size < 0) {
297 if (read)
298 break;
299 ret = size;
300 goto unlock_out;
301 }
302 if (pos >= size)
303 break;
304 if (count > size - pos)
305 count = size - pos;
306
307 this_round = count;
308 if (this_round > CON_BUF_SIZE)
309 this_round = CON_BUF_SIZE;
310
311 /* Perform the whole read into the local con_buf.
312 * Then we can drop the console spinlock and safely
313 * attempt to move it to userspace.
314 */
315
316 con_buf_start = con_buf0 = con_buf;
317 orig_count = this_round;
318 maxcol = vc->vc_cols;
319 if (uni_mode) {
320 unsigned int nr;
321
322 ret = vc_uniscr_check(vc);
323 if (ret)
324 break;
325 p /= 4;
326 row = p / vc->vc_cols;
327 col = p % maxcol;
328 nr = maxcol - col;
329 do {
330 if (nr > this_round/4)
331 nr = this_round/4;
332 vc_uniscr_copy_line(vc, con_buf0, viewed,
333 row, col, nr);
334 con_buf0 += nr * 4;
335 this_round -= nr * 4;
336 row++;
337 col = 0;
338 nr = maxcol;
339 } while (this_round);
340 } else if (!attr) {
341 org = screen_pos(vc, p, viewed);
342 col = p % maxcol;
343 p += maxcol - col;
344 while (this_round-- > 0) {
345 *con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
346 if (++col == maxcol) {
347 org = screen_pos(vc, p, viewed);
348 col = 0;
349 p += maxcol;
350 }
351 }
352 } else {
353 if (p < HEADER_SIZE) {
354 size_t tmp_count;
355
356 /* clamp header values if they don't fit */
357 con_buf0[0] = min(vc->vc_rows, 0xFFu);
358 con_buf0[1] = min(vc->vc_cols, 0xFFu);
359 getconsxy(vc, con_buf0 + 2);
360
361 con_buf_start += p;
362 this_round += p;
363 if (this_round > CON_BUF_SIZE) {
364 this_round = CON_BUF_SIZE;
365 orig_count = this_round - p;
366 }
367
368 tmp_count = HEADER_SIZE;
369 if (tmp_count > this_round)
370 tmp_count = this_round;
371
372 /* Advance state pointers and move on. */
373 this_round -= tmp_count;
374 p = HEADER_SIZE;
375 con_buf0 = con_buf + HEADER_SIZE;
376 /* If this_round >= 0, then p is even... */
377 } else if (p & 1) {
378 /* Skip first byte for output if start address is odd
379 * Update region sizes up/down depending on free
380 * space in buffer.
381 */
382 con_buf_start++;
383 if (this_round < CON_BUF_SIZE)
384 this_round++;
385 else
386 orig_count--;
387 }
388 if (this_round > 0) {
389 unsigned short *tmp_buf = (unsigned short *)con_buf0;
390
391 p -= HEADER_SIZE;
392 p /= 2;
393 col = p % maxcol;
394
395 org = screen_pos(vc, p, viewed);
396 p += maxcol - col;
397
398 /* Buffer has even length, so we can always copy
399 * character + attribute. We do not copy last byte
400 * to userspace if this_round is odd.
401 */
402 this_round = (this_round + 1) >> 1;
403
404 while (this_round) {
405 *tmp_buf++ = vcs_scr_readw(vc, org++);
406 this_round --;
407 if (++col == maxcol) {
408 org = screen_pos(vc, p, viewed);
409 col = 0;
410 p += maxcol;
411 }
412 }
413 }
414 }
415
416 /* Finally, release the console semaphore while we push
417 * all the data to userspace from our temporary buffer.
418 *
419 * AKPM: Even though it's a semaphore, we should drop it because
420 * the pagefault handling code may want to call printk().
421 */
422
423 console_unlock();
424 ret = copy_to_user(buf, con_buf_start, orig_count);
425 console_lock();
426
427 if (ret) {
428 read += (orig_count - ret);
429 ret = -EFAULT;
430 break;
431 }
432 buf += orig_count;
433 pos += orig_count;
434 read += orig_count;
435 count -= orig_count;
436 }
437 *ppos += read;
438 if (read)
439 ret = read;
440unlock_out:
441 console_unlock();
442 free_page((unsigned long) con_buf);
443 return ret;
444}
445
446static ssize_t
447vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
448{
449 struct inode *inode = file_inode(file);
450 struct vc_data *vc;
451 long pos;
452 long attr, size, written;
453 char *con_buf0;
454 int col, maxcol, viewed;
455 u16 *org0 = NULL, *org = NULL;
456 size_t ret;
457 char *con_buf;
458
459 if (use_unicode(inode))
460 return -EOPNOTSUPP;
461
462 con_buf = (char *) __get_free_page(GFP_KERNEL);
463 if (!con_buf)
464 return -ENOMEM;
465
466 pos = *ppos;
467
468 /* Select the proper current console and verify
469 * sanity of the situation under the console lock.
470 */
471 console_lock();
472
473 attr = use_attributes(inode);
474 ret = -ENXIO;
475 vc = vcs_vc(inode, &viewed);
476 if (!vc)
477 goto unlock_out;
478
479 size = vcs_size(inode);
480 ret = -EINVAL;
481 if (pos < 0 || pos > size)
482 goto unlock_out;
483 if (count > size - pos)
484 count = size - pos;
485 written = 0;
486 while (count) {
487 long this_round = count;
488 size_t orig_count;
489 long p;
490
491 if (this_round > CON_BUF_SIZE)
492 this_round = CON_BUF_SIZE;
493
494 /* Temporarily drop the console lock so that we can read
495 * in the write data from userspace safely.
496 */
497 console_unlock();
498 ret = copy_from_user(con_buf, buf, this_round);
499 console_lock();
500
501 if (ret) {
502 this_round -= ret;
503 if (!this_round) {
504 /* Abort loop if no data were copied. Otherwise
505 * fail with -EFAULT.
506 */
507 if (written)
508 break;
509 ret = -EFAULT;
510 goto unlock_out;
511 }
512 }
513
514 /* The vcs_size might have changed while we slept to grab
515 * the user buffer, so recheck.
516 * Return data written up to now on failure.
517 */
518 size = vcs_size(inode);
519 if (size < 0) {
520 if (written)
521 break;
522 ret = size;
523 goto unlock_out;
524 }
525 if (pos >= size)
526 break;
527 if (this_round > size - pos)
528 this_round = size - pos;
529
530 /* OK, now actually push the write to the console
531 * under the lock using the local kernel buffer.
532 */
533
534 con_buf0 = con_buf;
535 orig_count = this_round;
536 maxcol = vc->vc_cols;
537 p = pos;
538 if (!attr) {
539 org0 = org = screen_pos(vc, p, viewed);
540 col = p % maxcol;
541 p += maxcol - col;
542
543 while (this_round > 0) {
544 unsigned char c = *con_buf0++;
545
546 this_round--;
547 vcs_scr_writew(vc,
548 (vcs_scr_readw(vc, org) & 0xff00) | c, org);
549 org++;
550 if (++col == maxcol) {
551 org = screen_pos(vc, p, viewed);
552 col = 0;
553 p += maxcol;
554 }
555 }
556 } else {
557 if (p < HEADER_SIZE) {
558 char header[HEADER_SIZE];
559
560 getconsxy(vc, header + 2);
561 while (p < HEADER_SIZE && this_round > 0) {
562 this_round--;
563 header[p++] = *con_buf0++;
564 }
565 if (!viewed)
566 putconsxy(vc, header + 2);
567 }
568 p -= HEADER_SIZE;
569 col = (p/2) % maxcol;
570 if (this_round > 0) {
571 org0 = org = screen_pos(vc, p/2, viewed);
572 if ((p & 1) && this_round > 0) {
573 char c;
574
575 this_round--;
576 c = *con_buf0++;
577#ifdef __BIG_ENDIAN
578 vcs_scr_writew(vc, c |
579 (vcs_scr_readw(vc, org) & 0xff00), org);
580#else
581 vcs_scr_writew(vc, (c << 8) |
582 (vcs_scr_readw(vc, org) & 0xff), org);
583#endif
584 org++;
585 p++;
586 if (++col == maxcol) {
587 org = screen_pos(vc, p/2, viewed);
588 col = 0;
589 }
590 }
591 p /= 2;
592 p += maxcol - col;
593 }
594 while (this_round > 1) {
595 unsigned short w;
596
597 w = get_unaligned(((unsigned short *)con_buf0));
598 vcs_scr_writew(vc, w, org++);
599 con_buf0 += 2;
600 this_round -= 2;
601 if (++col == maxcol) {
602 org = screen_pos(vc, p, viewed);
603 col = 0;
604 p += maxcol;
605 }
606 }
607 if (this_round > 0) {
608 unsigned char c;
609
610 c = *con_buf0++;
611#ifdef __BIG_ENDIAN
612 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
613#else
614 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
615#endif
616 }
617 }
618 count -= orig_count;
619 written += orig_count;
620 buf += orig_count;
621 pos += orig_count;
622 if (org0)
623 update_region(vc, (unsigned long)(org0), org - org0);
624 }
625 *ppos += written;
626 ret = written;
627 if (written)
628 vcs_scr_updated(vc);
629
630unlock_out:
631 console_unlock();
632 free_page((unsigned long) con_buf);
633 return ret;
634}
635
636static __poll_t
637vcs_poll(struct file *file, poll_table *wait)
638{
639 struct vcs_poll_data *poll = vcs_poll_data_get(file);
640 __poll_t ret = DEFAULT_POLLMASK|EPOLLERR;
641
642 if (poll) {
643 poll_wait(file, &poll->waitq, wait);
644 switch (poll->event) {
645 case VT_UPDATE:
646 ret = DEFAULT_POLLMASK|EPOLLPRI;
647 break;
648 case VT_DEALLOCATE:
649 ret = DEFAULT_POLLMASK|EPOLLHUP|EPOLLERR;
650 break;
651 case 0:
652 ret = DEFAULT_POLLMASK;
653 break;
654 }
655 }
656 return ret;
657}
658
659static int
660vcs_fasync(int fd, struct file *file, int on)
661{
662 struct vcs_poll_data *poll = file->private_data;
663
664 if (!poll) {
665 /* don't allocate anything if all we want is disable fasync */
666 if (!on)
667 return 0;
668 poll = vcs_poll_data_get(file);
669 if (!poll)
670 return -ENOMEM;
671 }
672
673 return fasync_helper(fd, file, on, &poll->fasync);
674}
675
676static int
677vcs_open(struct inode *inode, struct file *filp)
678{
679 unsigned int currcons = console(inode);
680 bool attr = use_attributes(inode);
681 bool uni_mode = use_unicode(inode);
682 int ret = 0;
683
684 /* we currently don't support attributes in unicode mode */
685 if (attr && uni_mode)
686 return -EOPNOTSUPP;
687
688 console_lock();
689 if(currcons && !vc_cons_allocated(currcons-1))
690 ret = -ENXIO;
691 console_unlock();
692 return ret;
693}
694
695static int vcs_release(struct inode *inode, struct file *file)
696{
697 struct vcs_poll_data *poll = file->private_data;
698
699 if (poll)
700 vcs_poll_data_free(poll);
701 return 0;
702}
703
704static const struct file_operations vcs_fops = {
705 .llseek = vcs_lseek,
706 .read = vcs_read,
707 .write = vcs_write,
708 .poll = vcs_poll,
709 .fasync = vcs_fasync,
710 .open = vcs_open,
711 .release = vcs_release,
712};
713
714static struct class *vc_class;
715
716void vcs_make_sysfs(int index)
717{
718 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
719 "vcs%u", index + 1);
720 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 65), NULL,
721 "vcsu%u", index + 1);
722 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
723 "vcsa%u", index + 1);
724}
725
726void vcs_remove_sysfs(int index)
727{
728 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
729 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 65));
730 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
731}
732
733int __init vcs_init(void)
734{
735 unsigned int i;
736
737 if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
738 panic("unable to get major %d for vcs device", VCS_MAJOR);
739 vc_class = class_create(THIS_MODULE, "vc");
740
741 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
742 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 64), NULL, "vcsu");
743 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
744 for (i = 0; i < MIN_NR_CONSOLES; i++)
745 vcs_make_sysfs(i);
746 return 0;
747}
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
76struct 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
84static int
85vcs_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
118static void
119vcs_poll_data_free(struct vcs_poll_data *poll)
120{
121 unregister_vt_notifier(&poll->notifier);
122 kfree(poll);
123}
124
125static struct vcs_poll_data *
126vcs_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 */
183static 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 */
209static 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
228static 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
248static 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
276static 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
296static 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
364static ssize_t
365vcs_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 ret = -ENXIO;
407 vc = vcs_vc(inode, &viewed);
408 if (!vc)
409 goto unlock_out;
410
411 /* Check whether we are above size each round,
412 * as copy_to_user at the end of this loop
413 * could sleep.
414 */
415 size = vcs_size(vc, attr, uni_mode);
416 if (size < 0) {
417 if (read)
418 break;
419 ret = size;
420 goto unlock_out;
421 }
422 if (pos >= size)
423 break;
424 if (count > size - pos)
425 count = size - pos;
426
427 this_round = count;
428 if (this_round > CON_BUF_SIZE)
429 this_round = CON_BUF_SIZE;
430
431 /* Perform the whole read into the local con_buf.
432 * Then we can drop the console spinlock and safely
433 * attempt to move it to userspace.
434 */
435
436 if (uni_mode) {
437 ret = vcs_read_buf_uni(vc, con_buf, pos, this_round,
438 viewed);
439 if (ret)
440 break;
441 } else if (!attr) {
442 vcs_read_buf_noattr(vc, con_buf, pos, this_round,
443 viewed);
444 } else {
445 this_round = vcs_read_buf(vc, con_buf, pos, this_round,
446 viewed, &skip);
447 }
448
449 /* Finally, release the console semaphore while we push
450 * all the data to userspace from our temporary buffer.
451 *
452 * AKPM: Even though it's a semaphore, we should drop it because
453 * the pagefault handling code may want to call printk().
454 */
455
456 console_unlock();
457 ret = copy_to_user(buf, con_buf + skip, this_round);
458 console_lock();
459
460 if (ret) {
461 read += this_round - ret;
462 ret = -EFAULT;
463 break;
464 }
465 buf += this_round;
466 pos += this_round;
467 read += this_round;
468 count -= this_round;
469 }
470 *ppos += read;
471 if (read)
472 ret = read;
473unlock_out:
474 console_unlock();
475 free_page((unsigned long) con_buf);
476 return ret;
477}
478
479static u16 *vcs_write_buf_noattr(struct vc_data *vc, const char *con_buf,
480 unsigned int pos, unsigned int count, bool viewed, u16 **org0)
481{
482 u16 *org;
483 unsigned int col, maxcol = vc->vc_cols;
484
485 *org0 = org = screen_pos(vc, pos, viewed);
486 col = pos % maxcol;
487 pos += maxcol - col;
488
489 while (count > 0) {
490 unsigned char c = *con_buf++;
491
492 count--;
493 vcs_scr_writew(vc,
494 (vcs_scr_readw(vc, org) & 0xff00) | c, org);
495 org++;
496 if (++col == maxcol) {
497 org = screen_pos(vc, pos, viewed);
498 col = 0;
499 pos += maxcol;
500 }
501 }
502
503 return org;
504}
505
506/*
507 * Compilers (gcc 10) are unable to optimize the swap in cpu_to_le16. So do it
508 * the poor man way.
509 */
510static inline u16 vc_compile_le16(u8 hi, u8 lo)
511{
512#ifdef __BIG_ENDIAN
513 return (lo << 8u) | hi;
514#else
515 return (hi << 8u) | lo;
516#endif
517}
518
519static u16 *vcs_write_buf(struct vc_data *vc, const char *con_buf,
520 unsigned int pos, unsigned int count, bool viewed, u16 **org0)
521{
522 u16 *org;
523 unsigned int col, maxcol = vc->vc_cols;
524 unsigned char c;
525
526 /* header */
527 if (pos < HEADER_SIZE) {
528 char header[HEADER_SIZE];
529
530 getconsxy(vc, header + 2);
531 while (pos < HEADER_SIZE && count > 0) {
532 count--;
533 header[pos++] = *con_buf++;
534 }
535 if (!viewed)
536 putconsxy(vc, header + 2);
537 }
538
539 if (!count)
540 return NULL;
541
542 pos -= HEADER_SIZE;
543 col = (pos/2) % maxcol;
544
545 *org0 = org = screen_pos(vc, pos/2, viewed);
546
547 /* odd pos -- the first single character */
548 if (pos & 1) {
549 count--;
550 c = *con_buf++;
551 vcs_scr_writew(vc, vc_compile_le16(c, vcs_scr_readw(vc, org)),
552 org);
553 org++;
554 pos++;
555 if (++col == maxcol) {
556 org = screen_pos(vc, pos/2, viewed);
557 col = 0;
558 }
559 }
560
561 pos /= 2;
562 pos += maxcol - col;
563
564 /* even pos -- handle attr+character pairs */
565 while (count > 1) {
566 unsigned short w;
567
568 w = get_unaligned(((unsigned short *)con_buf));
569 vcs_scr_writew(vc, w, org++);
570 con_buf += 2;
571 count -= 2;
572 if (++col == maxcol) {
573 org = screen_pos(vc, pos, viewed);
574 col = 0;
575 pos += maxcol;
576 }
577 }
578
579 if (!count)
580 return org;
581
582 /* odd pos -- the remaining character */
583 c = *con_buf++;
584 vcs_scr_writew(vc, vc_compile_le16(vcs_scr_readw(vc, org) >> 8, c),
585 org);
586
587 return org;
588}
589
590static ssize_t
591vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
592{
593 struct inode *inode = file_inode(file);
594 struct vc_data *vc;
595 char *con_buf;
596 u16 *org0, *org;
597 unsigned int written;
598 int size;
599 ssize_t ret;
600 loff_t pos;
601 bool viewed, attr;
602
603 if (use_unicode(inode))
604 return -EOPNOTSUPP;
605
606 con_buf = (char *) __get_free_page(GFP_KERNEL);
607 if (!con_buf)
608 return -ENOMEM;
609
610 pos = *ppos;
611
612 /* Select the proper current console and verify
613 * sanity of the situation under the console lock.
614 */
615 console_lock();
616
617 attr = use_attributes(inode);
618 ret = -ENXIO;
619 vc = vcs_vc(inode, &viewed);
620 if (!vc)
621 goto unlock_out;
622
623 size = vcs_size(vc, attr, false);
624 if (size < 0) {
625 ret = size;
626 goto unlock_out;
627 }
628 ret = -EINVAL;
629 if (pos < 0 || pos > size)
630 goto unlock_out;
631 if (count > size - pos)
632 count = size - pos;
633 written = 0;
634 while (count) {
635 unsigned int this_round = count;
636
637 if (this_round > CON_BUF_SIZE)
638 this_round = CON_BUF_SIZE;
639
640 /* Temporarily drop the console lock so that we can read
641 * in the write data from userspace safely.
642 */
643 console_unlock();
644 ret = copy_from_user(con_buf, buf, this_round);
645 console_lock();
646
647 if (ret) {
648 this_round -= ret;
649 if (!this_round) {
650 /* Abort loop if no data were copied. Otherwise
651 * fail with -EFAULT.
652 */
653 if (written)
654 break;
655 ret = -EFAULT;
656 goto unlock_out;
657 }
658 }
659
660 /* The vcs_size might have changed while we slept to grab
661 * the user buffer, so recheck.
662 * Return data written up to now on failure.
663 */
664 size = vcs_size(vc, attr, false);
665 if (size < 0) {
666 if (written)
667 break;
668 ret = size;
669 goto unlock_out;
670 }
671 if (pos >= size)
672 break;
673 if (this_round > size - pos)
674 this_round = size - pos;
675
676 /* OK, now actually push the write to the console
677 * under the lock using the local kernel buffer.
678 */
679
680 if (attr)
681 org = vcs_write_buf(vc, con_buf, pos, this_round,
682 viewed, &org0);
683 else
684 org = vcs_write_buf_noattr(vc, con_buf, pos, this_round,
685 viewed, &org0);
686
687 count -= this_round;
688 written += this_round;
689 buf += this_round;
690 pos += this_round;
691 if (org)
692 update_region(vc, (unsigned long)(org0), org - org0);
693 }
694 *ppos += written;
695 ret = written;
696 if (written)
697 vcs_scr_updated(vc);
698
699unlock_out:
700 console_unlock();
701 free_page((unsigned long) con_buf);
702 return ret;
703}
704
705static __poll_t
706vcs_poll(struct file *file, poll_table *wait)
707{
708 struct vcs_poll_data *poll = vcs_poll_data_get(file);
709 __poll_t ret = DEFAULT_POLLMASK|EPOLLERR;
710
711 if (poll) {
712 poll_wait(file, &poll->waitq, wait);
713 switch (poll->event) {
714 case VT_UPDATE:
715 ret = DEFAULT_POLLMASK|EPOLLPRI;
716 break;
717 case VT_DEALLOCATE:
718 ret = DEFAULT_POLLMASK|EPOLLHUP|EPOLLERR;
719 break;
720 case 0:
721 ret = DEFAULT_POLLMASK;
722 break;
723 }
724 }
725 return ret;
726}
727
728static int
729vcs_fasync(int fd, struct file *file, int on)
730{
731 struct vcs_poll_data *poll = file->private_data;
732
733 if (!poll) {
734 /* don't allocate anything if all we want is disable fasync */
735 if (!on)
736 return 0;
737 poll = vcs_poll_data_get(file);
738 if (!poll)
739 return -ENOMEM;
740 }
741
742 return fasync_helper(fd, file, on, &poll->fasync);
743}
744
745static int
746vcs_open(struct inode *inode, struct file *filp)
747{
748 unsigned int currcons = console(inode);
749 bool attr = use_attributes(inode);
750 bool uni_mode = use_unicode(inode);
751 int ret = 0;
752
753 /* we currently don't support attributes in unicode mode */
754 if (attr && uni_mode)
755 return -EOPNOTSUPP;
756
757 console_lock();
758 if(currcons && !vc_cons_allocated(currcons-1))
759 ret = -ENXIO;
760 console_unlock();
761 return ret;
762}
763
764static int vcs_release(struct inode *inode, struct file *file)
765{
766 struct vcs_poll_data *poll = file->private_data;
767
768 if (poll)
769 vcs_poll_data_free(poll);
770 return 0;
771}
772
773static const struct file_operations vcs_fops = {
774 .llseek = vcs_lseek,
775 .read = vcs_read,
776 .write = vcs_write,
777 .poll = vcs_poll,
778 .fasync = vcs_fasync,
779 .open = vcs_open,
780 .release = vcs_release,
781};
782
783static struct class *vc_class;
784
785void vcs_make_sysfs(int index)
786{
787 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
788 "vcs%u", index + 1);
789 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 65), NULL,
790 "vcsu%u", index + 1);
791 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
792 "vcsa%u", index + 1);
793}
794
795void vcs_remove_sysfs(int index)
796{
797 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
798 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 65));
799 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
800}
801
802int __init vcs_init(void)
803{
804 unsigned int i;
805
806 if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
807 panic("unable to get major %d for vcs device", VCS_MAJOR);
808 vc_class = class_create(THIS_MODULE, "vc");
809
810 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
811 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 64), NULL, "vcsu");
812 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
813 for (i = 0; i < MIN_NR_CONSOLES; i++)
814 vcs_make_sysfs(i);
815 return 0;
816}