ia64/linux-2.6.18-xen.hg

view drivers/char/vc_screen.c @ 893:f994bfe9b93b

linux/blktap2: reduce TLB flush scope

c/s 885 added very coarse TLB flushing. Since these flushes always
follow single page updates, single page flushes (when available) are
sufficient.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
author Keir Fraser <keir.fraser@citrix.com>
date Thu Jun 04 10:32:57 2009 +0100 (2009-06-04)
parents 831230e53067
children
line source
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 */
24 #include <linux/kernel.h>
25 #include <linux/major.h>
26 #include <linux/errno.h>
27 #include <linux/tty.h>
28 #include <linux/sched.h>
29 #include <linux/interrupt.h>
30 #include <linux/mm.h>
31 #include <linux/init.h>
32 #include <linux/vt_kern.h>
33 #include <linux/selection.h>
34 #include <linux/kbd_kern.h>
35 #include <linux/console.h>
36 #include <linux/smp_lock.h>
37 #include <linux/device.h>
38 #include <asm/uaccess.h>
39 #include <asm/byteorder.h>
40 #include <asm/unaligned.h>
42 #undef attr
43 #undef org
44 #undef addr
45 #define HEADER_SIZE 4
47 static int
48 vcs_size(struct inode *inode)
49 {
50 int size;
51 int minor = iminor(inode);
52 int currcons = minor & 127;
53 struct vc_data *vc;
55 if (currcons == 0)
56 currcons = fg_console;
57 else
58 currcons--;
59 if (!vc_cons_allocated(currcons))
60 return -ENXIO;
61 vc = vc_cons[currcons].d;
63 size = vc->vc_rows * vc->vc_cols;
65 if (minor & 128)
66 size = 2*size + HEADER_SIZE;
67 return size;
68 }
70 static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
71 {
72 int size;
74 down(&con_buf_sem);
75 size = vcs_size(file->f_dentry->d_inode);
76 switch (orig) {
77 default:
78 up(&con_buf_sem);
79 return -EINVAL;
80 case 2:
81 offset += size;
82 break;
83 case 1:
84 offset += file->f_pos;
85 case 0:
86 break;
87 }
88 if (offset < 0 || offset > size) {
89 up(&con_buf_sem);
90 return -EINVAL;
91 }
92 file->f_pos = offset;
93 up(&con_buf_sem);
94 return file->f_pos;
95 }
98 static ssize_t
99 vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
100 {
101 struct inode *inode = file->f_dentry->d_inode;
102 unsigned int currcons = iminor(inode);
103 struct vc_data *vc;
104 long pos;
105 long viewed, attr, read;
106 int col, maxcol;
107 unsigned short *org = NULL;
108 ssize_t ret;
110 down(&con_buf_sem);
112 pos = *ppos;
114 /* Select the proper current console and verify
115 * sanity of the situation under the console lock.
116 */
117 acquire_console_sem();
119 attr = (currcons & 128);
120 currcons = (currcons & 127);
121 if (currcons == 0) {
122 currcons = fg_console;
123 viewed = 1;
124 } else {
125 currcons--;
126 viewed = 0;
127 }
128 ret = -ENXIO;
129 if (!vc_cons_allocated(currcons))
130 goto unlock_out;
131 vc = vc_cons[currcons].d;
133 ret = -EINVAL;
134 if (pos < 0)
135 goto unlock_out;
136 read = 0;
137 ret = 0;
138 while (count) {
139 char *con_buf0, *con_buf_start;
140 long this_round, size;
141 ssize_t orig_count;
142 long p = pos;
144 /* Check whether we are above size each round,
145 * as copy_to_user at the end of this loop
146 * could sleep.
147 */
148 size = vcs_size(inode);
149 if (pos >= size)
150 break;
151 if (count > size - pos)
152 count = size - pos;
154 this_round = count;
155 if (this_round > CON_BUF_SIZE)
156 this_round = CON_BUF_SIZE;
158 /* Perform the whole read into the local con_buf.
159 * Then we can drop the console spinlock and safely
160 * attempt to move it to userspace.
161 */
163 con_buf_start = con_buf0 = con_buf;
164 orig_count = this_round;
165 maxcol = vc->vc_cols;
166 if (!attr) {
167 org = screen_pos(vc, p, viewed);
168 col = p % maxcol;
169 p += maxcol - col;
170 while (this_round-- > 0) {
171 *con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
172 if (++col == maxcol) {
173 org = screen_pos(vc, p, viewed);
174 col = 0;
175 p += maxcol;
176 }
177 }
178 } else {
179 if (p < HEADER_SIZE) {
180 size_t tmp_count;
182 con_buf0[0] = (char)vc->vc_rows;
183 con_buf0[1] = (char)vc->vc_cols;
184 getconsxy(vc, con_buf0 + 2);
186 con_buf_start += p;
187 this_round += p;
188 if (this_round > CON_BUF_SIZE) {
189 this_round = CON_BUF_SIZE;
190 orig_count = this_round - p;
191 }
193 tmp_count = HEADER_SIZE;
194 if (tmp_count > this_round)
195 tmp_count = this_round;
197 /* Advance state pointers and move on. */
198 this_round -= tmp_count;
199 p = HEADER_SIZE;
200 con_buf0 = con_buf + HEADER_SIZE;
201 /* If this_round >= 0, then p is even... */
202 } else if (p & 1) {
203 /* Skip first byte for output if start address is odd
204 * Update region sizes up/down depending on free
205 * space in buffer.
206 */
207 con_buf_start++;
208 if (this_round < CON_BUF_SIZE)
209 this_round++;
210 else
211 orig_count--;
212 }
213 if (this_round > 0) {
214 unsigned short *tmp_buf = (unsigned short *)con_buf0;
216 p -= HEADER_SIZE;
217 p /= 2;
218 col = p % maxcol;
220 org = screen_pos(vc, p, viewed);
221 p += maxcol - col;
223 /* Buffer has even length, so we can always copy
224 * character + attribute. We do not copy last byte
225 * to userspace if this_round is odd.
226 */
227 this_round = (this_round + 1) >> 1;
229 while (this_round) {
230 *tmp_buf++ = vcs_scr_readw(vc, org++);
231 this_round --;
232 if (++col == maxcol) {
233 org = screen_pos(vc, p, viewed);
234 col = 0;
235 p += maxcol;
236 }
237 }
238 }
239 }
241 /* Finally, release the console semaphore while we push
242 * all the data to userspace from our temporary buffer.
243 *
244 * AKPM: Even though it's a semaphore, we should drop it because
245 * the pagefault handling code may want to call printk().
246 */
248 release_console_sem();
249 ret = copy_to_user(buf, con_buf_start, orig_count);
250 acquire_console_sem();
252 if (ret) {
253 read += (orig_count - ret);
254 ret = -EFAULT;
255 break;
256 }
257 buf += orig_count;
258 pos += orig_count;
259 read += orig_count;
260 count -= orig_count;
261 }
262 *ppos += read;
263 if (read)
264 ret = read;
265 unlock_out:
266 release_console_sem();
267 up(&con_buf_sem);
268 return ret;
269 }
271 static ssize_t
272 vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
273 {
274 struct inode *inode = file->f_dentry->d_inode;
275 unsigned int currcons = iminor(inode);
276 struct vc_data *vc;
277 long pos;
278 long viewed, attr, size, written;
279 char *con_buf0;
280 int col, maxcol;
281 u16 *org0 = NULL, *org = NULL;
282 size_t ret;
284 down(&con_buf_sem);
286 pos = *ppos;
288 /* Select the proper current console and verify
289 * sanity of the situation under the console lock.
290 */
291 acquire_console_sem();
293 attr = (currcons & 128);
294 currcons = (currcons & 127);
296 if (currcons == 0) {
297 currcons = fg_console;
298 viewed = 1;
299 } else {
300 currcons--;
301 viewed = 0;
302 }
303 ret = -ENXIO;
304 if (!vc_cons_allocated(currcons))
305 goto unlock_out;
306 vc = vc_cons[currcons].d;
308 size = vcs_size(inode);
309 ret = -EINVAL;
310 if (pos < 0 || pos > size)
311 goto unlock_out;
312 if (count > size - pos)
313 count = size - pos;
314 written = 0;
315 while (count) {
316 long this_round = count;
317 size_t orig_count;
318 long p;
320 if (this_round > CON_BUF_SIZE)
321 this_round = CON_BUF_SIZE;
323 /* Temporarily drop the console lock so that we can read
324 * in the write data from userspace safely.
325 */
326 release_console_sem();
327 ret = copy_from_user(con_buf, buf, this_round);
328 acquire_console_sem();
330 if (ret) {
331 this_round -= ret;
332 if (!this_round) {
333 /* Abort loop if no data were copied. Otherwise
334 * fail with -EFAULT.
335 */
336 if (written)
337 break;
338 ret = -EFAULT;
339 goto unlock_out;
340 }
341 }
343 /* The vcs_size might have changed while we slept to grab
344 * the user buffer, so recheck.
345 * Return data written up to now on failure.
346 */
347 size = vcs_size(inode);
348 if (pos >= size)
349 break;
350 if (this_round > size - pos)
351 this_round = size - pos;
353 /* OK, now actually push the write to the console
354 * under the lock using the local kernel buffer.
355 */
357 con_buf0 = con_buf;
358 orig_count = this_round;
359 maxcol = vc->vc_cols;
360 p = pos;
361 if (!attr) {
362 org0 = org = screen_pos(vc, p, viewed);
363 col = p % maxcol;
364 p += maxcol - col;
366 while (this_round > 0) {
367 unsigned char c = *con_buf0++;
369 this_round--;
370 vcs_scr_writew(vc,
371 (vcs_scr_readw(vc, org) & 0xff00) | c, org);
372 org++;
373 if (++col == maxcol) {
374 org = screen_pos(vc, p, viewed);
375 col = 0;
376 p += maxcol;
377 }
378 }
379 } else {
380 if (p < HEADER_SIZE) {
381 char header[HEADER_SIZE];
383 getconsxy(vc, header + 2);
384 while (p < HEADER_SIZE && this_round > 0) {
385 this_round--;
386 header[p++] = *con_buf0++;
387 }
388 if (!viewed)
389 putconsxy(vc, header + 2);
390 }
391 p -= HEADER_SIZE;
392 col = (p/2) % maxcol;
393 if (this_round > 0) {
394 org0 = org = screen_pos(vc, p/2, viewed);
395 if ((p & 1) && this_round > 0) {
396 char c;
398 this_round--;
399 c = *con_buf0++;
400 #ifdef __BIG_ENDIAN
401 vcs_scr_writew(vc, c |
402 (vcs_scr_readw(vc, org) & 0xff00), org);
403 #else
404 vcs_scr_writew(vc, (c << 8) |
405 (vcs_scr_readw(vc, org) & 0xff), org);
406 #endif
407 org++;
408 p++;
409 if (++col == maxcol) {
410 org = screen_pos(vc, p/2, viewed);
411 col = 0;
412 }
413 }
414 p /= 2;
415 p += maxcol - col;
416 }
417 while (this_round > 1) {
418 unsigned short w;
420 w = get_unaligned(((unsigned short *)con_buf0));
421 vcs_scr_writew(vc, w, org++);
422 con_buf0 += 2;
423 this_round -= 2;
424 if (++col == maxcol) {
425 org = screen_pos(vc, p, viewed);
426 col = 0;
427 p += maxcol;
428 }
429 }
430 if (this_round > 0) {
431 unsigned char c;
433 c = *con_buf0++;
434 #ifdef __BIG_ENDIAN
435 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
436 #else
437 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
438 #endif
439 }
440 }
441 count -= orig_count;
442 written += orig_count;
443 buf += orig_count;
444 pos += orig_count;
445 if (org0)
446 update_region(vc, (unsigned long)(org0), org - org0);
447 }
448 *ppos += written;
449 ret = written;
451 unlock_out:
452 release_console_sem();
454 up(&con_buf_sem);
456 return ret;
457 }
459 static int
460 vcs_open(struct inode *inode, struct file *filp)
461 {
462 unsigned int currcons = iminor(inode) & 127;
463 if(currcons && !vc_cons_allocated(currcons-1))
464 return -ENXIO;
465 return 0;
466 }
468 static const struct file_operations vcs_fops = {
469 .llseek = vcs_lseek,
470 .read = vcs_read,
471 .write = vcs_write,
472 .open = vcs_open,
473 };
475 static struct class *vc_class;
477 void vcs_make_devfs(struct tty_struct *tty)
478 {
479 class_device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 1),
480 NULL, "vcs%u", tty->index + 1);
481 class_device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 129),
482 NULL, "vcsa%u", tty->index + 1);
483 }
484 void vcs_remove_devfs(struct tty_struct *tty)
485 {
486 class_device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 1));
487 class_device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 129));
488 }
490 int __init vcs_init(void)
491 {
492 if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
493 panic("unable to get major %d for vcs device", VCS_MAJOR);
494 vc_class = class_create(THIS_MODULE, "vc");
496 class_device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
497 class_device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
498 return 0;
499 }