header cleaning: don't include smp_lock.h when not used
[linux-3.10.git] / drivers / char / vc_screen.c
1 /*
2  * linux/drivers/char/vc_screen.c
3  *
4  * Provide access to virtual console memory.
5  * /dev/vcs0: the screen as it is being viewed right now (possibly scrolled)
6  * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
7  *            [minor: N]
8  *
9  * /dev/vcsaN: idem, but including attributes, and prefixed with
10  *      the 4 bytes lines,columns,x,y (as screendump used to give).
11  *      Attribute/character pair is in native endianity.
12  *            [minor: N+128]
13  *
14  * This replaces screendump and part of selection, so that the system
15  * administrator can control access using file system permissions.
16  *
17  * aeb@cwi.nl - efter Friedas begravelse - 950211
18  *
19  * machek@k332.feld.cvut.cz - modified not to send characters to wrong console
20  *       - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
21  *       - making it shorter - scr_readw are macros which expand in PRETTY long code
22  */
23
24 #include <linux/kernel.h>
25 #include <linux/major.h>
26 #include <linux/errno.h>
27 #include <linux/tty.h>
28 #include <linux/interrupt.h>
29 #include <linux/mm.h>
30 #include <linux/init.h>
31 #include <linux/vt_kern.h>
32 #include <linux/selection.h>
33 #include <linux/kbd_kern.h>
34 #include <linux/console.h>
35 #include <linux/device.h>
36 #include <asm/uaccess.h>
37 #include <asm/byteorder.h>
38 #include <asm/unaligned.h>
39
40 #undef attr
41 #undef org
42 #undef addr
43 #define HEADER_SIZE     4
44
45 static int
46 vcs_size(struct inode *inode)
47 {
48         int size;
49         int minor = iminor(inode);
50         int currcons = minor & 127;
51         struct vc_data *vc;
52
53         if (currcons == 0)
54                 currcons = fg_console;
55         else
56                 currcons--;
57         if (!vc_cons_allocated(currcons))
58                 return -ENXIO;
59         vc = vc_cons[currcons].d;
60
61         size = vc->vc_rows * vc->vc_cols;
62
63         if (minor & 128)
64                 size = 2*size + HEADER_SIZE;
65         return size;
66 }
67
68 static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
69 {
70         int size;
71
72         down(&con_buf_sem);
73         size = vcs_size(file->f_path.dentry->d_inode);
74         switch (orig) {
75                 default:
76                         up(&con_buf_sem);
77                         return -EINVAL;
78                 case 2:
79                         offset += size;
80                         break;
81                 case 1:
82                         offset += file->f_pos;
83                 case 0:
84                         break;
85         }
86         if (offset < 0 || offset > size) {
87                 up(&con_buf_sem);
88                 return -EINVAL;
89         }
90         file->f_pos = offset;
91         up(&con_buf_sem);
92         return file->f_pos;
93 }
94
95
96 static ssize_t
97 vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
98 {
99         struct inode *inode = file->f_path.dentry->d_inode;
100         unsigned int currcons = iminor(inode);
101         struct vc_data *vc;
102         long pos;
103         long viewed, attr, read;
104         int col, maxcol;
105         unsigned short *org = NULL;
106         ssize_t ret;
107
108         down(&con_buf_sem);
109
110         pos = *ppos;
111
112         /* Select the proper current console and verify
113          * sanity of the situation under the console lock.
114          */
115         acquire_console_sem();
116
117         attr = (currcons & 128);
118         currcons = (currcons & 127);
119         if (currcons == 0) {
120                 currcons = fg_console;
121                 viewed = 1;
122         } else {
123                 currcons--;
124                 viewed = 0;
125         }
126         ret = -ENXIO;
127         if (!vc_cons_allocated(currcons))
128                 goto unlock_out;
129         vc = vc_cons[currcons].d;
130
131         ret = -EINVAL;
132         if (pos < 0)
133                 goto unlock_out;
134         read = 0;
135         ret = 0;
136         while (count) {
137                 char *con_buf0, *con_buf_start;
138                 long this_round, size;
139                 ssize_t orig_count;
140                 long p = pos;
141
142                 /* Check whether we are above size each round,
143                  * as copy_to_user at the end of this loop
144                  * could sleep.
145                  */
146                 size = vcs_size(inode);
147                 if (pos >= size)
148                         break;
149                 if (count > size - pos)
150                         count = size - pos;
151
152                 this_round = count;
153                 if (this_round > CON_BUF_SIZE)
154                         this_round = CON_BUF_SIZE;
155
156                 /* Perform the whole read into the local con_buf.
157                  * Then we can drop the console spinlock and safely
158                  * attempt to move it to userspace.
159                  */
160
161                 con_buf_start = con_buf0 = con_buf;
162                 orig_count = this_round;
163                 maxcol = vc->vc_cols;
164                 if (!attr) {
165                         org = screen_pos(vc, p, viewed);
166                         col = p % maxcol;
167                         p += maxcol - col;
168                         while (this_round-- > 0) {
169                                 *con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
170                                 if (++col == maxcol) {
171                                         org = screen_pos(vc, p, viewed);
172                                         col = 0;
173                                         p += maxcol;
174                                 }
175                         }
176                 } else {
177                         if (p < HEADER_SIZE) {
178                                 size_t tmp_count;
179
180                                 con_buf0[0] = (char)vc->vc_rows;
181                                 con_buf0[1] = (char)vc->vc_cols;
182                                 getconsxy(vc, con_buf0 + 2);
183
184                                 con_buf_start += p;
185                                 this_round += p;
186                                 if (this_round > CON_BUF_SIZE) {
187                                         this_round = CON_BUF_SIZE;
188                                         orig_count = this_round - p;
189                                 }
190
191                                 tmp_count = HEADER_SIZE;
192                                 if (tmp_count > this_round)
193                                         tmp_count = this_round;
194
195                                 /* Advance state pointers and move on. */
196                                 this_round -= tmp_count;
197                                 p = HEADER_SIZE;
198                                 con_buf0 = con_buf + HEADER_SIZE;
199                                 /* If this_round >= 0, then p is even... */
200                         } else if (p & 1) {
201                                 /* Skip first byte for output if start address is odd
202                                  * Update region sizes up/down depending on free
203                                  * space in buffer.
204                                  */
205                                 con_buf_start++;
206                                 if (this_round < CON_BUF_SIZE)
207                                         this_round++;
208                                 else
209                                         orig_count--;
210                         }
211                         if (this_round > 0) {
212                                 unsigned short *tmp_buf = (unsigned short *)con_buf0;
213
214                                 p -= HEADER_SIZE;
215                                 p /= 2;
216                                 col = p % maxcol;
217
218                                 org = screen_pos(vc, p, viewed);
219                                 p += maxcol - col;
220
221                                 /* Buffer has even length, so we can always copy
222                                  * character + attribute. We do not copy last byte
223                                  * to userspace if this_round is odd.
224                                  */
225                                 this_round = (this_round + 1) >> 1;
226
227                                 while (this_round) {
228                                         *tmp_buf++ = vcs_scr_readw(vc, org++);
229                                         this_round --;
230                                         if (++col == maxcol) {
231                                                 org = screen_pos(vc, p, viewed);
232                                                 col = 0;
233                                                 p += maxcol;
234                                         }
235                                 }
236                         }
237                 }
238
239                 /* Finally, release the console semaphore while we push
240                  * all the data to userspace from our temporary buffer.
241                  *
242                  * AKPM: Even though it's a semaphore, we should drop it because
243                  * the pagefault handling code may want to call printk().
244                  */
245
246                 release_console_sem();
247                 ret = copy_to_user(buf, con_buf_start, orig_count);
248                 acquire_console_sem();
249
250                 if (ret) {
251                         read += (orig_count - ret);
252                         ret = -EFAULT;
253                         break;
254                 }
255                 buf += orig_count;
256                 pos += orig_count;
257                 read += orig_count;
258                 count -= orig_count;
259         }
260         *ppos += read;
261         if (read)
262                 ret = read;
263 unlock_out:
264         release_console_sem();
265         up(&con_buf_sem);
266         return ret;
267 }
268
269 static ssize_t
270 vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
271 {
272         struct inode *inode = file->f_path.dentry->d_inode;
273         unsigned int currcons = iminor(inode);
274         struct vc_data *vc;
275         long pos;
276         long viewed, attr, size, written;
277         char *con_buf0;
278         int col, maxcol;
279         u16 *org0 = NULL, *org = NULL;
280         size_t ret;
281
282         down(&con_buf_sem);
283
284         pos = *ppos;
285
286         /* Select the proper current console and verify
287          * sanity of the situation under the console lock.
288          */
289         acquire_console_sem();
290
291         attr = (currcons & 128);
292         currcons = (currcons & 127);
293
294         if (currcons == 0) {
295                 currcons = fg_console;
296                 viewed = 1;
297         } else {
298                 currcons--;
299                 viewed = 0;
300         }
301         ret = -ENXIO;
302         if (!vc_cons_allocated(currcons))
303                 goto unlock_out;
304         vc = vc_cons[currcons].d;
305
306         size = vcs_size(inode);
307         ret = -EINVAL;
308         if (pos < 0 || pos > size)
309                 goto unlock_out;
310         if (count > size - pos)
311                 count = size - pos;
312         written = 0;
313         while (count) {
314                 long this_round = count;
315                 size_t orig_count;
316                 long p;
317
318                 if (this_round > CON_BUF_SIZE)
319                         this_round = CON_BUF_SIZE;
320
321                 /* Temporarily drop the console lock so that we can read
322                  * in the write data from userspace safely.
323                  */
324                 release_console_sem();
325                 ret = copy_from_user(con_buf, buf, this_round);
326                 acquire_console_sem();
327
328                 if (ret) {
329                         this_round -= ret;
330                         if (!this_round) {
331                                 /* Abort loop if no data were copied. Otherwise
332                                  * fail with -EFAULT.
333                                  */
334                                 if (written)
335                                         break;
336                                 ret = -EFAULT;
337                                 goto unlock_out;
338                         }
339                 }
340
341                 /* The vcs_size might have changed while we slept to grab
342                  * the user buffer, so recheck.
343                  * Return data written up to now on failure.
344                  */
345                 size = vcs_size(inode);
346                 if (pos >= size)
347                         break;
348                 if (this_round > size - pos)
349                         this_round = size - pos;
350
351                 /* OK, now actually push the write to the console
352                  * under the lock using the local kernel buffer.
353                  */
354
355                 con_buf0 = con_buf;
356                 orig_count = this_round;
357                 maxcol = vc->vc_cols;
358                 p = pos;
359                 if (!attr) {
360                         org0 = org = screen_pos(vc, p, viewed);
361                         col = p % maxcol;
362                         p += maxcol - col;
363
364                         while (this_round > 0) {
365                                 unsigned char c = *con_buf0++;
366
367                                 this_round--;
368                                 vcs_scr_writew(vc,
369                                                (vcs_scr_readw(vc, org) & 0xff00) | c, org);
370                                 org++;
371                                 if (++col == maxcol) {
372                                         org = screen_pos(vc, p, viewed);
373                                         col = 0;
374                                         p += maxcol;
375                                 }
376                         }
377                 } else {
378                         if (p < HEADER_SIZE) {
379                                 char header[HEADER_SIZE];
380
381                                 getconsxy(vc, header + 2);
382                                 while (p < HEADER_SIZE && this_round > 0) {
383                                         this_round--;
384                                         header[p++] = *con_buf0++;
385                                 }
386                                 if (!viewed)
387                                         putconsxy(vc, header + 2);
388                         }
389                         p -= HEADER_SIZE;
390                         col = (p/2) % maxcol;
391                         if (this_round > 0) {
392                                 org0 = org = screen_pos(vc, p/2, viewed);
393                                 if ((p & 1) && this_round > 0) {
394                                         char c;
395
396                                         this_round--;
397                                         c = *con_buf0++;
398 #ifdef __BIG_ENDIAN
399                                         vcs_scr_writew(vc, c |
400                                              (vcs_scr_readw(vc, org) & 0xff00), org);
401 #else
402                                         vcs_scr_writew(vc, (c << 8) |
403                                              (vcs_scr_readw(vc, org) & 0xff), org);
404 #endif
405                                         org++;
406                                         p++;
407                                         if (++col == maxcol) {
408                                                 org = screen_pos(vc, p/2, viewed);
409                                                 col = 0;
410                                         }
411                                 }
412                                 p /= 2;
413                                 p += maxcol - col;
414                         }
415                         while (this_round > 1) {
416                                 unsigned short w;
417
418                                 w = get_unaligned(((unsigned short *)con_buf0));
419                                 vcs_scr_writew(vc, w, org++);
420                                 con_buf0 += 2;
421                                 this_round -= 2;
422                                 if (++col == maxcol) {
423                                         org = screen_pos(vc, p, viewed);
424                                         col = 0;
425                                         p += maxcol;
426                                 }
427                         }
428                         if (this_round > 0) {
429                                 unsigned char c;
430
431                                 c = *con_buf0++;
432 #ifdef __BIG_ENDIAN
433                                 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
434 #else
435                                 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
436 #endif
437                         }
438                 }
439                 count -= orig_count;
440                 written += orig_count;
441                 buf += orig_count;
442                 pos += orig_count;
443                 if (org0)
444                         update_region(vc, (unsigned long)(org0), org - org0);
445         }
446         *ppos += written;
447         ret = written;
448
449 unlock_out:
450         release_console_sem();
451
452         up(&con_buf_sem);
453
454         return ret;
455 }
456
457 static int
458 vcs_open(struct inode *inode, struct file *filp)
459 {
460         unsigned int currcons = iminor(inode) & 127;
461         if(currcons && !vc_cons_allocated(currcons-1))
462                 return -ENXIO;
463         return 0;
464 }
465
466 static const struct file_operations vcs_fops = {
467         .llseek         = vcs_lseek,
468         .read           = vcs_read,
469         .write          = vcs_write,
470         .open           = vcs_open,
471 };
472
473 static struct class *vc_class;
474
475 void vcs_make_sysfs(struct tty_struct *tty)
476 {
477         device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 1),
478                         "vcs%u", tty->index + 1);
479         device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 129),
480                         "vcsa%u", tty->index + 1);
481 }
482
483 void vcs_remove_sysfs(struct tty_struct *tty)
484 {
485         device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 1));
486         device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 129));
487 }
488
489 int __init vcs_init(void)
490 {
491         if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
492                 panic("unable to get major %d for vcs device", VCS_MAJOR);
493         vc_class = class_create(THIS_MODULE, "vc");
494
495         device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), "vcs");
496         device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), "vcsa");
497         return 0;
498 }