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Replace <asm/uaccess.h> with <linux/uaccess.h> globally
[mirror_ubuntu-hirsute-kernel.git] / drivers / tty / vt / vc_screen.c
1 /*
2 * Provide access to virtual console memory.
3 * /dev/vcs0: the screen as it is being viewed right now (possibly scrolled)
4 * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
5 * [minor: N]
6 *
7 * /dev/vcsaN: idem, but including attributes, and prefixed with
8 * the 4 bytes lines,columns,x,y (as screendump used to give).
9 * Attribute/character pair is in native endianity.
10 * [minor: N+128]
11 *
12 * This replaces screendump and part of selection, so that the system
13 * administrator can control access using file system permissions.
14 *
15 * aeb@cwi.nl - efter Friedas begravelse - 950211
16 *
17 * machek@k332.feld.cvut.cz - modified not to send characters to wrong console
18 * - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
19 * - making it shorter - scr_readw are macros which expand in PRETTY long code
20 */
21
22 #include <linux/kernel.h>
23 #include <linux/major.h>
24 #include <linux/errno.h>
25 #include <linux/export.h>
26 #include <linux/tty.h>
27 #include <linux/interrupt.h>
28 #include <linux/mm.h>
29 #include <linux/init.h>
30 #include <linux/vt_kern.h>
31 #include <linux/selection.h>
32 #include <linux/kbd_kern.h>
33 #include <linux/console.h>
34 #include <linux/device.h>
35 #include <linux/sched.h>
36 #include <linux/fs.h>
37 #include <linux/poll.h>
38 #include <linux/signal.h>
39 #include <linux/slab.h>
40 #include <linux/notifier.h>
41
42 #include <linux/uaccess.h>
43 #include <asm/byteorder.h>
44 #include <asm/unaligned.h>
45
46 #undef attr
47 #undef org
48 #undef addr
49 #define HEADER_SIZE 4
50
51 #define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
52
53 struct vcs_poll_data {
54 struct notifier_block notifier;
55 unsigned int cons_num;
56 bool seen_last_update;
57 wait_queue_head_t waitq;
58 struct fasync_struct *fasync;
59 };
60
61 static int
62 vcs_notifier(struct notifier_block *nb, unsigned long code, void *_param)
63 {
64 struct vt_notifier_param *param = _param;
65 struct vc_data *vc = param->vc;
66 struct vcs_poll_data *poll =
67 container_of(nb, struct vcs_poll_data, notifier);
68 int currcons = poll->cons_num;
69
70 if (code != VT_UPDATE)
71 return NOTIFY_DONE;
72
73 if (currcons == 0)
74 currcons = fg_console;
75 else
76 currcons--;
77 if (currcons != vc->vc_num)
78 return NOTIFY_DONE;
79
80 poll->seen_last_update = false;
81 wake_up_interruptible(&poll->waitq);
82 kill_fasync(&poll->fasync, SIGIO, POLL_IN);
83 return NOTIFY_OK;
84 }
85
86 static void
87 vcs_poll_data_free(struct vcs_poll_data *poll)
88 {
89 unregister_vt_notifier(&poll->notifier);
90 kfree(poll);
91 }
92
93 static struct vcs_poll_data *
94 vcs_poll_data_get(struct file *file)
95 {
96 struct vcs_poll_data *poll = file->private_data, *kill = NULL;
97
98 if (poll)
99 return poll;
100
101 poll = kzalloc(sizeof(*poll), GFP_KERNEL);
102 if (!poll)
103 return NULL;
104 poll->cons_num = iminor(file_inode(file)) & 127;
105 init_waitqueue_head(&poll->waitq);
106 poll->notifier.notifier_call = vcs_notifier;
107 if (register_vt_notifier(&poll->notifier) != 0) {
108 kfree(poll);
109 return NULL;
110 }
111
112 /*
113 * This code may be called either through ->poll() or ->fasync().
114 * If we have two threads using the same file descriptor, they could
115 * both enter this function, both notice that the structure hasn't
116 * been allocated yet and go ahead allocating it in parallel, but
117 * only one of them must survive and be shared otherwise we'd leak
118 * memory with a dangling notifier callback.
119 */
120 spin_lock(&file->f_lock);
121 if (!file->private_data) {
122 file->private_data = poll;
123 } else {
124 /* someone else raced ahead of us */
125 kill = poll;
126 poll = file->private_data;
127 }
128 spin_unlock(&file->f_lock);
129 if (kill)
130 vcs_poll_data_free(kill);
131
132 return poll;
133 }
134
135 /*
136 * Returns VC for inode.
137 * Must be called with console_lock.
138 */
139 static struct vc_data*
140 vcs_vc(struct inode *inode, int *viewed)
141 {
142 unsigned int currcons = iminor(inode) & 127;
143
144 WARN_CONSOLE_UNLOCKED();
145
146 if (currcons == 0) {
147 currcons = fg_console;
148 if (viewed)
149 *viewed = 1;
150 } else {
151 currcons--;
152 if (viewed)
153 *viewed = 0;
154 }
155 return vc_cons[currcons].d;
156 }
157
158 /*
159 * Returns size for VC carried by inode.
160 * Must be called with console_lock.
161 */
162 static int
163 vcs_size(struct inode *inode)
164 {
165 int size;
166 int minor = iminor(inode);
167 struct vc_data *vc;
168
169 WARN_CONSOLE_UNLOCKED();
170
171 vc = vcs_vc(inode, NULL);
172 if (!vc)
173 return -ENXIO;
174
175 size = vc->vc_rows * vc->vc_cols;
176
177 if (minor & 128)
178 size = 2*size + HEADER_SIZE;
179 return size;
180 }
181
182 static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
183 {
184 int size;
185
186 console_lock();
187 size = vcs_size(file_inode(file));
188 console_unlock();
189 if (size < 0)
190 return size;
191 return fixed_size_llseek(file, offset, orig, size);
192 }
193
194
195 static ssize_t
196 vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
197 {
198 struct inode *inode = file_inode(file);
199 unsigned int currcons = iminor(inode);
200 struct vc_data *vc;
201 struct vcs_poll_data *poll;
202 long pos;
203 long attr, read;
204 int col, maxcol, viewed;
205 unsigned short *org = NULL;
206 ssize_t ret;
207 char *con_buf;
208
209 con_buf = (char *) __get_free_page(GFP_KERNEL);
210 if (!con_buf)
211 return -ENOMEM;
212
213 pos = *ppos;
214
215 /* Select the proper current console and verify
216 * sanity of the situation under the console lock.
217 */
218 console_lock();
219
220 attr = (currcons & 128);
221 ret = -ENXIO;
222 vc = vcs_vc(inode, &viewed);
223 if (!vc)
224 goto unlock_out;
225
226 ret = -EINVAL;
227 if (pos < 0)
228 goto unlock_out;
229 poll = file->private_data;
230 if (count && poll)
231 poll->seen_last_update = true;
232 read = 0;
233 ret = 0;
234 while (count) {
235 char *con_buf0, *con_buf_start;
236 long this_round, size;
237 ssize_t orig_count;
238 long p = pos;
239
240 /* Check whether we are above size each round,
241 * as copy_to_user at the end of this loop
242 * could sleep.
243 */
244 size = vcs_size(inode);
245 if (size < 0) {
246 if (read)
247 break;
248 ret = size;
249 goto unlock_out;
250 }
251 if (pos >= size)
252 break;
253 if (count > size - pos)
254 count = size - pos;
255
256 this_round = count;
257 if (this_round > CON_BUF_SIZE)
258 this_round = CON_BUF_SIZE;
259
260 /* Perform the whole read into the local con_buf.
261 * Then we can drop the console spinlock and safely
262 * attempt to move it to userspace.
263 */
264
265 con_buf_start = con_buf0 = con_buf;
266 orig_count = this_round;
267 maxcol = vc->vc_cols;
268 if (!attr) {
269 org = screen_pos(vc, p, viewed);
270 col = p % maxcol;
271 p += maxcol - col;
272 while (this_round-- > 0) {
273 *con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
274 if (++col == maxcol) {
275 org = screen_pos(vc, p, viewed);
276 col = 0;
277 p += maxcol;
278 }
279 }
280 } else {
281 if (p < HEADER_SIZE) {
282 size_t tmp_count;
283
284 con_buf0[0] = (char)vc->vc_rows;
285 con_buf0[1] = (char)vc->vc_cols;
286 getconsxy(vc, con_buf0 + 2);
287
288 con_buf_start += p;
289 this_round += p;
290 if (this_round > CON_BUF_SIZE) {
291 this_round = CON_BUF_SIZE;
292 orig_count = this_round - p;
293 }
294
295 tmp_count = HEADER_SIZE;
296 if (tmp_count > this_round)
297 tmp_count = this_round;
298
299 /* Advance state pointers and move on. */
300 this_round -= tmp_count;
301 p = HEADER_SIZE;
302 con_buf0 = con_buf + HEADER_SIZE;
303 /* If this_round >= 0, then p is even... */
304 } else if (p & 1) {
305 /* Skip first byte for output if start address is odd
306 * Update region sizes up/down depending on free
307 * space in buffer.
308 */
309 con_buf_start++;
310 if (this_round < CON_BUF_SIZE)
311 this_round++;
312 else
313 orig_count--;
314 }
315 if (this_round > 0) {
316 unsigned short *tmp_buf = (unsigned short *)con_buf0;
317
318 p -= HEADER_SIZE;
319 p /= 2;
320 col = p % maxcol;
321
322 org = screen_pos(vc, p, viewed);
323 p += maxcol - col;
324
325 /* Buffer has even length, so we can always copy
326 * character + attribute. We do not copy last byte
327 * to userspace if this_round is odd.
328 */
329 this_round = (this_round + 1) >> 1;
330
331 while (this_round) {
332 *tmp_buf++ = vcs_scr_readw(vc, org++);
333 this_round --;
334 if (++col == maxcol) {
335 org = screen_pos(vc, p, viewed);
336 col = 0;
337 p += maxcol;
338 }
339 }
340 }
341 }
342
343 /* Finally, release the console semaphore while we push
344 * all the data to userspace from our temporary buffer.
345 *
346 * AKPM: Even though it's a semaphore, we should drop it because
347 * the pagefault handling code may want to call printk().
348 */
349
350 console_unlock();
351 ret = copy_to_user(buf, con_buf_start, orig_count);
352 console_lock();
353
354 if (ret) {
355 read += (orig_count - ret);
356 ret = -EFAULT;
357 break;
358 }
359 buf += orig_count;
360 pos += orig_count;
361 read += orig_count;
362 count -= orig_count;
363 }
364 *ppos += read;
365 if (read)
366 ret = read;
367 unlock_out:
368 console_unlock();
369 free_page((unsigned long) con_buf);
370 return ret;
371 }
372
373 static ssize_t
374 vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
375 {
376 struct inode *inode = file_inode(file);
377 unsigned int currcons = iminor(inode);
378 struct vc_data *vc;
379 long pos;
380 long attr, size, written;
381 char *con_buf0;
382 int col, maxcol, viewed;
383 u16 *org0 = NULL, *org = NULL;
384 size_t ret;
385 char *con_buf;
386
387 con_buf = (char *) __get_free_page(GFP_KERNEL);
388 if (!con_buf)
389 return -ENOMEM;
390
391 pos = *ppos;
392
393 /* Select the proper current console and verify
394 * sanity of the situation under the console lock.
395 */
396 console_lock();
397
398 attr = (currcons & 128);
399 ret = -ENXIO;
400 vc = vcs_vc(inode, &viewed);
401 if (!vc)
402 goto unlock_out;
403
404 size = vcs_size(inode);
405 ret = -EINVAL;
406 if (pos < 0 || pos > size)
407 goto unlock_out;
408 if (count > size - pos)
409 count = size - pos;
410 written = 0;
411 while (count) {
412 long this_round = count;
413 size_t orig_count;
414 long p;
415
416 if (this_round > CON_BUF_SIZE)
417 this_round = CON_BUF_SIZE;
418
419 /* Temporarily drop the console lock so that we can read
420 * in the write data from userspace safely.
421 */
422 console_unlock();
423 ret = copy_from_user(con_buf, buf, this_round);
424 console_lock();
425
426 if (ret) {
427 this_round -= ret;
428 if (!this_round) {
429 /* Abort loop if no data were copied. Otherwise
430 * fail with -EFAULT.
431 */
432 if (written)
433 break;
434 ret = -EFAULT;
435 goto unlock_out;
436 }
437 }
438
439 /* The vcs_size might have changed while we slept to grab
440 * the user buffer, so recheck.
441 * Return data written up to now on failure.
442 */
443 size = vcs_size(inode);
444 if (size < 0) {
445 if (written)
446 break;
447 ret = size;
448 goto unlock_out;
449 }
450 if (pos >= size)
451 break;
452 if (this_round > size - pos)
453 this_round = size - pos;
454
455 /* OK, now actually push the write to the console
456 * under the lock using the local kernel buffer.
457 */
458
459 con_buf0 = con_buf;
460 orig_count = this_round;
461 maxcol = vc->vc_cols;
462 p = pos;
463 if (!attr) {
464 org0 = org = screen_pos(vc, p, viewed);
465 col = p % maxcol;
466 p += maxcol - col;
467
468 while (this_round > 0) {
469 unsigned char c = *con_buf0++;
470
471 this_round--;
472 vcs_scr_writew(vc,
473 (vcs_scr_readw(vc, org) & 0xff00) | c, org);
474 org++;
475 if (++col == maxcol) {
476 org = screen_pos(vc, p, viewed);
477 col = 0;
478 p += maxcol;
479 }
480 }
481 } else {
482 if (p < HEADER_SIZE) {
483 char header[HEADER_SIZE];
484
485 getconsxy(vc, header + 2);
486 while (p < HEADER_SIZE && this_round > 0) {
487 this_round--;
488 header[p++] = *con_buf0++;
489 }
490 if (!viewed)
491 putconsxy(vc, header + 2);
492 }
493 p -= HEADER_SIZE;
494 col = (p/2) % maxcol;
495 if (this_round > 0) {
496 org0 = org = screen_pos(vc, p/2, viewed);
497 if ((p & 1) && this_round > 0) {
498 char c;
499
500 this_round--;
501 c = *con_buf0++;
502 #ifdef __BIG_ENDIAN
503 vcs_scr_writew(vc, c |
504 (vcs_scr_readw(vc, org) & 0xff00), org);
505 #else
506 vcs_scr_writew(vc, (c << 8) |
507 (vcs_scr_readw(vc, org) & 0xff), org);
508 #endif
509 org++;
510 p++;
511 if (++col == maxcol) {
512 org = screen_pos(vc, p/2, viewed);
513 col = 0;
514 }
515 }
516 p /= 2;
517 p += maxcol - col;
518 }
519 while (this_round > 1) {
520 unsigned short w;
521
522 w = get_unaligned(((unsigned short *)con_buf0));
523 vcs_scr_writew(vc, w, org++);
524 con_buf0 += 2;
525 this_round -= 2;
526 if (++col == maxcol) {
527 org = screen_pos(vc, p, viewed);
528 col = 0;
529 p += maxcol;
530 }
531 }
532 if (this_round > 0) {
533 unsigned char c;
534
535 c = *con_buf0++;
536 #ifdef __BIG_ENDIAN
537 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
538 #else
539 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
540 #endif
541 }
542 }
543 count -= orig_count;
544 written += orig_count;
545 buf += orig_count;
546 pos += orig_count;
547 if (org0)
548 update_region(vc, (unsigned long)(org0), org - org0);
549 }
550 *ppos += written;
551 ret = written;
552 if (written)
553 vcs_scr_updated(vc);
554
555 unlock_out:
556 console_unlock();
557 free_page((unsigned long) con_buf);
558 return ret;
559 }
560
561 static unsigned int
562 vcs_poll(struct file *file, poll_table *wait)
563 {
564 struct vcs_poll_data *poll = vcs_poll_data_get(file);
565 int ret = DEFAULT_POLLMASK|POLLERR|POLLPRI;
566
567 if (poll) {
568 poll_wait(file, &poll->waitq, wait);
569 if (poll->seen_last_update)
570 ret = DEFAULT_POLLMASK;
571 }
572 return ret;
573 }
574
575 static int
576 vcs_fasync(int fd, struct file *file, int on)
577 {
578 struct vcs_poll_data *poll = file->private_data;
579
580 if (!poll) {
581 /* don't allocate anything if all we want is disable fasync */
582 if (!on)
583 return 0;
584 poll = vcs_poll_data_get(file);
585 if (!poll)
586 return -ENOMEM;
587 }
588
589 return fasync_helper(fd, file, on, &poll->fasync);
590 }
591
592 static int
593 vcs_open(struct inode *inode, struct file *filp)
594 {
595 unsigned int currcons = iminor(inode) & 127;
596 int ret = 0;
597
598 console_lock();
599 if(currcons && !vc_cons_allocated(currcons-1))
600 ret = -ENXIO;
601 console_unlock();
602 return ret;
603 }
604
605 static int vcs_release(struct inode *inode, struct file *file)
606 {
607 struct vcs_poll_data *poll = file->private_data;
608
609 if (poll)
610 vcs_poll_data_free(poll);
611 return 0;
612 }
613
614 static const struct file_operations vcs_fops = {
615 .llseek = vcs_lseek,
616 .read = vcs_read,
617 .write = vcs_write,
618 .poll = vcs_poll,
619 .fasync = vcs_fasync,
620 .open = vcs_open,
621 .release = vcs_release,
622 };
623
624 static struct class *vc_class;
625
626 void vcs_make_sysfs(int index)
627 {
628 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
629 "vcs%u", index + 1);
630 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
631 "vcsa%u", index + 1);
632 }
633
634 void vcs_remove_sysfs(int index)
635 {
636 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
637 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
638 }
639
640 int __init vcs_init(void)
641 {
642 unsigned int i;
643
644 if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
645 panic("unable to get major %d for vcs device", VCS_MAJOR);
646 vc_class = class_create(THIS_MODULE, "vc");
647
648 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
649 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
650 for (i = 0; i < MIN_NR_CONSOLES; i++)
651 vcs_make_sysfs(i);
652 return 0;
653 }
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