Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/kernel/printk.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * Modified to make sys_syslog() more flexible: added commands to | |
7 | * return the last 4k of kernel messages, regardless of whether | |
8 | * they've been read or not. Added option to suppress kernel printk's | |
9 | * to the console. Added hook for sending the console messages | |
10 | * elsewhere, in preparation for a serial line console (someday). | |
11 | * Ted Ts'o, 2/11/93. | |
12 | * Modified for sysctl support, 1/8/97, Chris Horn. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 LT |
15 | * Rewrote bits to get rid of console_lock |
16 | * 01Mar01 Andrew Morton <andrewm@uow.edu.au> | |
17 | */ | |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
23 | #include <linux/smp_lock.h> | |
24 | #include <linux/console.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/interrupt.h> /* For in_interrupt() */ | |
28 | #include <linux/config.h> | |
29 | #include <linux/delay.h> | |
30 | #include <linux/smp.h> | |
31 | #include <linux/security.h> | |
32 | #include <linux/bootmem.h> | |
33 | #include <linux/syscalls.h> | |
34 | ||
35 | #include <asm/uaccess.h> | |
36 | ||
37 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) | |
38 | ||
39 | /* printk's without a loglevel use this.. */ | |
40 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ | |
41 | ||
42 | /* We show everything that is MORE important than this.. */ | |
43 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
44 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
45 | ||
46 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
47 | ||
48 | int console_printk[4] = { | |
49 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
50 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
51 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
52 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
53 | }; | |
54 | ||
55 | EXPORT_SYMBOL(console_printk); | |
56 | ||
57 | /* | |
58 | * Low lever drivers may need that to know if they can schedule in | |
59 | * their unblank() callback or not. So let's export it. | |
60 | */ | |
61 | int oops_in_progress; | |
62 | EXPORT_SYMBOL(oops_in_progress); | |
63 | ||
64 | /* | |
65 | * console_sem protects the console_drivers list, and also | |
66 | * provides serialisation for access to the entire console | |
67 | * driver system. | |
68 | */ | |
69 | static DECLARE_MUTEX(console_sem); | |
70 | struct console *console_drivers; | |
71 | /* | |
72 | * This is used for debugging the mess that is the VT code by | |
73 | * keeping track if we have the console semaphore held. It's | |
74 | * definitely not the perfect debug tool (we don't know if _WE_ | |
75 | * hold it are racing, but it helps tracking those weird code | |
76 | * path in the console code where we end up in places I want | |
77 | * locked without the console sempahore held | |
78 | */ | |
79 | static int console_locked; | |
80 | ||
81 | /* | |
82 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
83 | * It is also used in interesting ways to provide interlocking in | |
84 | * release_console_sem(). | |
85 | */ | |
86 | static DEFINE_SPINLOCK(logbuf_lock); | |
87 | ||
1da177e4 LT |
88 | #define LOG_BUF_MASK (log_buf_len-1) |
89 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) | |
90 | ||
91 | /* | |
92 | * The indices into log_buf are not constrained to log_buf_len - they | |
93 | * must be masked before subscripting | |
94 | */ | |
95 | static unsigned long log_start; /* Index into log_buf: next char to be read by syslog() */ | |
96 | static unsigned long con_start; /* Index into log_buf: next char to be sent to consoles */ | |
97 | static unsigned long log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
98 | |
99 | /* | |
100 | * Array of consoles built from command line options (console=) | |
101 | */ | |
102 | struct console_cmdline | |
103 | { | |
104 | char name[8]; /* Name of the driver */ | |
105 | int index; /* Minor dev. to use */ | |
106 | char *options; /* Options for the driver */ | |
107 | }; | |
108 | ||
109 | #define MAX_CMDLINECONSOLES 8 | |
110 | ||
111 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
112 | static int selected_console = -1; | |
113 | static int preferred_console = -1; | |
114 | ||
115 | /* Flag: console code may call schedule() */ | |
116 | static int console_may_schedule; | |
117 | ||
d59745ce MM |
118 | #ifdef CONFIG_PRINTK |
119 | ||
120 | static char __log_buf[__LOG_BUF_LEN]; | |
121 | static char *log_buf = __log_buf; | |
122 | static int log_buf_len = __LOG_BUF_LEN; | |
123 | static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */ | |
124 | ||
1da177e4 LT |
125 | static int __init log_buf_len_setup(char *str) |
126 | { | |
127 | unsigned long size = memparse(str, &str); | |
128 | unsigned long flags; | |
129 | ||
130 | if (size) | |
131 | size = roundup_pow_of_two(size); | |
132 | if (size > log_buf_len) { | |
133 | unsigned long start, dest_idx, offset; | |
40dc5651 | 134 | char *new_log_buf; |
1da177e4 LT |
135 | |
136 | new_log_buf = alloc_bootmem(size); | |
137 | if (!new_log_buf) { | |
40dc5651 | 138 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
139 | goto out; |
140 | } | |
141 | ||
142 | spin_lock_irqsave(&logbuf_lock, flags); | |
143 | log_buf_len = size; | |
144 | log_buf = new_log_buf; | |
145 | ||
146 | offset = start = min(con_start, log_start); | |
147 | dest_idx = 0; | |
148 | while (start != log_end) { | |
149 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
150 | start++; | |
151 | dest_idx++; | |
152 | } | |
153 | log_start -= offset; | |
154 | con_start -= offset; | |
155 | log_end -= offset; | |
156 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
157 | ||
40dc5651 | 158 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
159 | } |
160 | out: | |
1da177e4 LT |
161 | return 1; |
162 | } | |
163 | ||
164 | __setup("log_buf_len=", log_buf_len_setup); | |
165 | ||
166 | /* | |
167 | * Commands to do_syslog: | |
168 | * | |
169 | * 0 -- Close the log. Currently a NOP. | |
170 | * 1 -- Open the log. Currently a NOP. | |
171 | * 2 -- Read from the log. | |
172 | * 3 -- Read all messages remaining in the ring buffer. | |
173 | * 4 -- Read and clear all messages remaining in the ring buffer | |
174 | * 5 -- Clear ring buffer. | |
175 | * 6 -- Disable printk's to console | |
176 | * 7 -- Enable printk's to console | |
177 | * 8 -- Set level of messages printed to console | |
178 | * 9 -- Return number of unread characters in the log buffer | |
179 | * 10 -- Return size of the log buffer | |
180 | */ | |
40dc5651 | 181 | int do_syslog(int type, char __user *buf, int len) |
1da177e4 LT |
182 | { |
183 | unsigned long i, j, limit, count; | |
184 | int do_clear = 0; | |
185 | char c; | |
186 | int error = 0; | |
187 | ||
188 | error = security_syslog(type); | |
189 | if (error) | |
190 | return error; | |
191 | ||
192 | switch (type) { | |
193 | case 0: /* Close log */ | |
194 | break; | |
195 | case 1: /* Open log */ | |
196 | break; | |
197 | case 2: /* Read from log */ | |
198 | error = -EINVAL; | |
199 | if (!buf || len < 0) | |
200 | goto out; | |
201 | error = 0; | |
202 | if (!len) | |
203 | goto out; | |
204 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
205 | error = -EFAULT; | |
206 | goto out; | |
207 | } | |
40dc5651 JJ |
208 | error = wait_event_interruptible(log_wait, |
209 | (log_start - log_end)); | |
1da177e4 LT |
210 | if (error) |
211 | goto out; | |
212 | i = 0; | |
213 | spin_lock_irq(&logbuf_lock); | |
214 | while (!error && (log_start != log_end) && i < len) { | |
215 | c = LOG_BUF(log_start); | |
216 | log_start++; | |
217 | spin_unlock_irq(&logbuf_lock); | |
218 | error = __put_user(c,buf); | |
219 | buf++; | |
220 | i++; | |
221 | cond_resched(); | |
222 | spin_lock_irq(&logbuf_lock); | |
223 | } | |
224 | spin_unlock_irq(&logbuf_lock); | |
225 | if (!error) | |
226 | error = i; | |
227 | break; | |
228 | case 4: /* Read/clear last kernel messages */ | |
40dc5651 | 229 | do_clear = 1; |
1da177e4 LT |
230 | /* FALL THRU */ |
231 | case 3: /* Read last kernel messages */ | |
232 | error = -EINVAL; | |
233 | if (!buf || len < 0) | |
234 | goto out; | |
235 | error = 0; | |
236 | if (!len) | |
237 | goto out; | |
238 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
239 | error = -EFAULT; | |
240 | goto out; | |
241 | } | |
242 | count = len; | |
243 | if (count > log_buf_len) | |
244 | count = log_buf_len; | |
245 | spin_lock_irq(&logbuf_lock); | |
246 | if (count > logged_chars) | |
247 | count = logged_chars; | |
248 | if (do_clear) | |
249 | logged_chars = 0; | |
250 | limit = log_end; | |
251 | /* | |
252 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 253 | * printk() could overwrite the messages |
1da177e4 LT |
254 | * we try to copy to user space. Therefore |
255 | * the messages are copied in reverse. <manfreds> | |
256 | */ | |
40dc5651 | 257 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
258 | j = limit-1-i; |
259 | if (j + log_buf_len < log_end) | |
260 | break; | |
261 | c = LOG_BUF(j); | |
262 | spin_unlock_irq(&logbuf_lock); | |
263 | error = __put_user(c,&buf[count-1-i]); | |
264 | cond_resched(); | |
265 | spin_lock_irq(&logbuf_lock); | |
266 | } | |
267 | spin_unlock_irq(&logbuf_lock); | |
268 | if (error) | |
269 | break; | |
270 | error = i; | |
40dc5651 | 271 | if (i != count) { |
1da177e4 LT |
272 | int offset = count-error; |
273 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 274 | for (i = 0; i < error; i++) { |
1da177e4 LT |
275 | if (__get_user(c,&buf[i+offset]) || |
276 | __put_user(c,&buf[i])) { | |
277 | error = -EFAULT; | |
278 | break; | |
279 | } | |
280 | cond_resched(); | |
281 | } | |
282 | } | |
283 | break; | |
284 | case 5: /* Clear ring buffer */ | |
285 | logged_chars = 0; | |
286 | break; | |
287 | case 6: /* Disable logging to console */ | |
288 | console_loglevel = minimum_console_loglevel; | |
289 | break; | |
290 | case 7: /* Enable logging to console */ | |
291 | console_loglevel = default_console_loglevel; | |
292 | break; | |
293 | case 8: /* Set level of messages printed to console */ | |
294 | error = -EINVAL; | |
295 | if (len < 1 || len > 8) | |
296 | goto out; | |
297 | if (len < minimum_console_loglevel) | |
298 | len = minimum_console_loglevel; | |
299 | console_loglevel = len; | |
300 | error = 0; | |
301 | break; | |
302 | case 9: /* Number of chars in the log buffer */ | |
303 | error = log_end - log_start; | |
304 | break; | |
305 | case 10: /* Size of the log buffer */ | |
306 | error = log_buf_len; | |
307 | break; | |
308 | default: | |
309 | error = -EINVAL; | |
310 | break; | |
311 | } | |
312 | out: | |
313 | return error; | |
314 | } | |
315 | ||
40dc5651 | 316 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
1da177e4 LT |
317 | { |
318 | return do_syslog(type, buf, len); | |
319 | } | |
320 | ||
321 | /* | |
322 | * Call the console drivers on a range of log_buf | |
323 | */ | |
324 | static void __call_console_drivers(unsigned long start, unsigned long end) | |
325 | { | |
326 | struct console *con; | |
327 | ||
328 | for (con = console_drivers; con; con = con->next) { | |
329 | if ((con->flags & CON_ENABLED) && con->write) | |
330 | con->write(con, &LOG_BUF(start), end - start); | |
331 | } | |
332 | } | |
333 | ||
334 | /* | |
335 | * Write out chars from start to end - 1 inclusive | |
336 | */ | |
337 | static void _call_console_drivers(unsigned long start, | |
338 | unsigned long end, int msg_log_level) | |
339 | { | |
340 | if (msg_log_level < console_loglevel && | |
341 | console_drivers && start != end) { | |
342 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
343 | /* wrapped write */ | |
344 | __call_console_drivers(start & LOG_BUF_MASK, | |
345 | log_buf_len); | |
346 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
347 | } else { | |
348 | __call_console_drivers(start, end); | |
349 | } | |
350 | } | |
351 | } | |
352 | ||
353 | /* | |
354 | * Call the console drivers, asking them to write out | |
355 | * log_buf[start] to log_buf[end - 1]. | |
356 | * The console_sem must be held. | |
357 | */ | |
358 | static void call_console_drivers(unsigned long start, unsigned long end) | |
359 | { | |
360 | unsigned long cur_index, start_print; | |
361 | static int msg_level = -1; | |
362 | ||
363 | if (((long)(start - end)) > 0) | |
364 | BUG(); | |
365 | ||
366 | cur_index = start; | |
367 | start_print = start; | |
368 | while (cur_index != end) { | |
40dc5651 JJ |
369 | if (msg_level < 0 && ((end - cur_index) > 2) && |
370 | LOG_BUF(cur_index + 0) == '<' && | |
371 | LOG_BUF(cur_index + 1) >= '0' && | |
372 | LOG_BUF(cur_index + 1) <= '7' && | |
373 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
374 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
375 | cur_index += 3; | |
376 | start_print = cur_index; | |
377 | } | |
378 | while (cur_index != end) { | |
379 | char c = LOG_BUF(cur_index); | |
1da177e4 | 380 | |
40dc5651 | 381 | cur_index++; |
1da177e4 LT |
382 | if (c == '\n') { |
383 | if (msg_level < 0) { | |
384 | /* | |
385 | * printk() has already given us loglevel tags in | |
386 | * the buffer. This code is here in case the | |
387 | * log buffer has wrapped right round and scribbled | |
388 | * on those tags | |
389 | */ | |
390 | msg_level = default_message_loglevel; | |
391 | } | |
392 | _call_console_drivers(start_print, cur_index, msg_level); | |
393 | msg_level = -1; | |
394 | start_print = cur_index; | |
395 | break; | |
396 | } | |
397 | } | |
398 | } | |
399 | _call_console_drivers(start_print, end, msg_level); | |
400 | } | |
401 | ||
402 | static void emit_log_char(char c) | |
403 | { | |
404 | LOG_BUF(log_end) = c; | |
405 | log_end++; | |
406 | if (log_end - log_start > log_buf_len) | |
407 | log_start = log_end - log_buf_len; | |
408 | if (log_end - con_start > log_buf_len) | |
409 | con_start = log_end - log_buf_len; | |
410 | if (logged_chars < log_buf_len) | |
411 | logged_chars++; | |
412 | } | |
413 | ||
414 | /* | |
415 | * Zap console related locks when oopsing. Only zap at most once | |
416 | * every 10 seconds, to leave time for slow consoles to print a | |
417 | * full oops. | |
418 | */ | |
419 | static void zap_locks(void) | |
420 | { | |
421 | static unsigned long oops_timestamp; | |
422 | ||
423 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 424 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
425 | return; |
426 | ||
427 | oops_timestamp = jiffies; | |
428 | ||
429 | /* If a crash is occurring, make sure we can't deadlock */ | |
430 | spin_lock_init(&logbuf_lock); | |
431 | /* And make sure that we print immediately */ | |
432 | init_MUTEX(&console_sem); | |
433 | } | |
434 | ||
435 | #if defined(CONFIG_PRINTK_TIME) | |
436 | static int printk_time = 1; | |
437 | #else | |
438 | static int printk_time = 0; | |
439 | #endif | |
440 | ||
441 | static int __init printk_time_setup(char *str) | |
442 | { | |
443 | if (*str) | |
444 | return 0; | |
445 | printk_time = 1; | |
446 | return 1; | |
447 | } | |
448 | ||
449 | __setup("time", printk_time_setup); | |
450 | ||
31f6d9d6 AM |
451 | __attribute__((weak)) unsigned long long printk_clock(void) |
452 | { | |
453 | return sched_clock(); | |
454 | } | |
455 | ||
ddad86c2 MW |
456 | /** |
457 | * printk - print a kernel message | |
458 | * @fmt: format string | |
459 | * | |
1da177e4 | 460 | * This is printk. It can be called from any context. We want it to work. |
40dc5651 | 461 | * |
1da177e4 LT |
462 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
463 | * call the console drivers. If we fail to get the semaphore we place the output | |
464 | * into the log buffer and return. The current holder of the console_sem will | |
465 | * notice the new output in release_console_sem() and will send it to the | |
466 | * consoles before releasing the semaphore. | |
467 | * | |
468 | * One effect of this deferred printing is that code which calls printk() and | |
469 | * then changes console_loglevel may break. This is because console_loglevel | |
470 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
471 | * |
472 | * See also: | |
473 | * printf(3) | |
1da177e4 | 474 | */ |
d59745ce | 475 | |
1da177e4 LT |
476 | asmlinkage int printk(const char *fmt, ...) |
477 | { | |
478 | va_list args; | |
479 | int r; | |
480 | ||
481 | va_start(args, fmt); | |
482 | r = vprintk(fmt, args); | |
483 | va_end(args); | |
484 | ||
485 | return r; | |
486 | } | |
487 | ||
fe21773d DH |
488 | /* cpu currently holding logbuf_lock */ |
489 | static volatile unsigned int printk_cpu = UINT_MAX; | |
490 | ||
1da177e4 LT |
491 | asmlinkage int vprintk(const char *fmt, va_list args) |
492 | { | |
493 | unsigned long flags; | |
494 | int printed_len; | |
495 | char *p; | |
496 | static char printk_buf[1024]; | |
497 | static int log_level_unknown = 1; | |
498 | ||
fe21773d DH |
499 | preempt_disable(); |
500 | if (unlikely(oops_in_progress) && printk_cpu == smp_processor_id()) | |
501 | /* If a crash is occurring during printk() on this CPU, | |
502 | * make sure we can't deadlock */ | |
1da177e4 LT |
503 | zap_locks(); |
504 | ||
505 | /* This stops the holder of console_sem just where we want him */ | |
506 | spin_lock_irqsave(&logbuf_lock, flags); | |
fe21773d | 507 | printk_cpu = smp_processor_id(); |
1da177e4 LT |
508 | |
509 | /* Emit the output into the temporary buffer */ | |
510 | printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args); | |
511 | ||
512 | /* | |
513 | * Copy the output into log_buf. If the caller didn't provide | |
514 | * appropriate log level tags, we insert them here | |
515 | */ | |
516 | for (p = printk_buf; *p; p++) { | |
517 | if (log_level_unknown) { | |
518 | /* log_level_unknown signals the start of a new line */ | |
519 | if (printk_time) { | |
520 | int loglev_char; | |
521 | char tbuf[50], *tp; | |
522 | unsigned tlen; | |
523 | unsigned long long t; | |
524 | unsigned long nanosec_rem; | |
525 | ||
526 | /* | |
527 | * force the log level token to be | |
528 | * before the time output. | |
529 | */ | |
530 | if (p[0] == '<' && p[1] >='0' && | |
531 | p[1] <= '7' && p[2] == '>') { | |
532 | loglev_char = p[1]; | |
533 | p += 3; | |
025510cd | 534 | printed_len -= 3; |
1da177e4 LT |
535 | } else { |
536 | loglev_char = default_message_loglevel | |
537 | + '0'; | |
538 | } | |
31f6d9d6 | 539 | t = printk_clock(); |
1da177e4 LT |
540 | nanosec_rem = do_div(t, 1000000000); |
541 | tlen = sprintf(tbuf, | |
542 | "<%c>[%5lu.%06lu] ", | |
543 | loglev_char, | |
544 | (unsigned long)t, | |
545 | nanosec_rem/1000); | |
546 | ||
547 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
548 | emit_log_char(*tp); | |
025510cd | 549 | printed_len += tlen; |
1da177e4 LT |
550 | } else { |
551 | if (p[0] != '<' || p[1] < '0' || | |
552 | p[1] > '7' || p[2] != '>') { | |
553 | emit_log_char('<'); | |
554 | emit_log_char(default_message_loglevel | |
555 | + '0'); | |
556 | emit_log_char('>'); | |
025510cd | 557 | printed_len += 3; |
1da177e4 | 558 | } |
1da177e4 LT |
559 | } |
560 | log_level_unknown = 0; | |
561 | if (!*p) | |
562 | break; | |
563 | } | |
564 | emit_log_char(*p); | |
565 | if (*p == '\n') | |
566 | log_level_unknown = 1; | |
567 | } | |
568 | ||
ac255752 | 569 | if (!cpu_online(smp_processor_id())) { |
1da177e4 LT |
570 | /* |
571 | * Some console drivers may assume that per-cpu resources have | |
572 | * been allocated. So don't allow them to be called by this | |
573 | * CPU until it is officially up. We shouldn't be calling into | |
574 | * random console drivers on a CPU which doesn't exist yet.. | |
575 | */ | |
fe21773d | 576 | printk_cpu = UINT_MAX; |
1da177e4 LT |
577 | spin_unlock_irqrestore(&logbuf_lock, flags); |
578 | goto out; | |
579 | } | |
580 | if (!down_trylock(&console_sem)) { | |
581 | console_locked = 1; | |
582 | /* | |
583 | * We own the drivers. We can drop the spinlock and let | |
584 | * release_console_sem() print the text | |
585 | */ | |
fe21773d | 586 | printk_cpu = UINT_MAX; |
1da177e4 LT |
587 | spin_unlock_irqrestore(&logbuf_lock, flags); |
588 | console_may_schedule = 0; | |
589 | release_console_sem(); | |
590 | } else { | |
591 | /* | |
592 | * Someone else owns the drivers. We drop the spinlock, which | |
593 | * allows the semaphore holder to proceed and to call the | |
594 | * console drivers with the output which we just produced. | |
595 | */ | |
fe21773d | 596 | printk_cpu = UINT_MAX; |
1da177e4 LT |
597 | spin_unlock_irqrestore(&logbuf_lock, flags); |
598 | } | |
599 | out: | |
fe21773d | 600 | preempt_enable(); |
1da177e4 LT |
601 | return printed_len; |
602 | } | |
603 | EXPORT_SYMBOL(printk); | |
604 | EXPORT_SYMBOL(vprintk); | |
605 | ||
d59745ce MM |
606 | #else |
607 | ||
40dc5651 | 608 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
d59745ce MM |
609 | { |
610 | return 0; | |
611 | } | |
612 | ||
40dc5651 JJ |
613 | int do_syslog(int type, char __user *buf, int len) |
614 | { | |
615 | return 0; | |
616 | } | |
617 | ||
618 | static void call_console_drivers(unsigned long start, unsigned long end) | |
619 | { | |
620 | } | |
d59745ce MM |
621 | |
622 | #endif | |
623 | ||
2ea1c539 JB |
624 | /* |
625 | * Set up a list of consoles. Called from init/main.c | |
626 | */ | |
627 | static int __init console_setup(char *str) | |
628 | { | |
629 | char name[sizeof(console_cmdline[0].name)]; | |
630 | char *s, *options; | |
631 | int idx; | |
632 | ||
633 | /* | |
634 | * Decode str into name, index, options. | |
635 | */ | |
636 | if (str[0] >= '0' && str[0] <= '9') { | |
637 | strcpy(name, "ttyS"); | |
638 | strncpy(name + 4, str, sizeof(name) - 5); | |
639 | } else { | |
640 | strncpy(name, str, sizeof(name) - 1); | |
641 | } | |
642 | name[sizeof(name) - 1] = 0; | |
643 | if ((options = strchr(str, ',')) != NULL) | |
644 | *(options++) = 0; | |
645 | #ifdef __sparc__ | |
646 | if (!strcmp(str, "ttya")) | |
647 | strcpy(name, "ttyS0"); | |
648 | if (!strcmp(str, "ttyb")) | |
649 | strcpy(name, "ttyS1"); | |
650 | #endif | |
651 | for (s = name; *s; s++) | |
652 | if ((*s >= '0' && *s <= '9') || *s == ',') | |
653 | break; | |
654 | idx = simple_strtoul(s, NULL, 10); | |
655 | *s = 0; | |
656 | ||
657 | add_preferred_console(name, idx, options); | |
658 | return 1; | |
659 | } | |
660 | __setup("console=", console_setup); | |
661 | ||
3c0547ba MM |
662 | /** |
663 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
664 | * @name: device name |
665 | * @idx: device index | |
666 | * @options: options for this console | |
3c0547ba MM |
667 | * |
668 | * The last preferred console added will be used for kernel messages | |
669 | * and stdin/out/err for init. Normally this is used by console_setup | |
670 | * above to handle user-supplied console arguments; however it can also | |
671 | * be used by arch-specific code either to override the user or more | |
672 | * commonly to provide a default console (ie from PROM variables) when | |
673 | * the user has not supplied one. | |
674 | */ | |
675 | int __init add_preferred_console(char *name, int idx, char *options) | |
676 | { | |
677 | struct console_cmdline *c; | |
678 | int i; | |
679 | ||
680 | /* | |
681 | * See if this tty is not yet registered, and | |
682 | * if we have a slot free. | |
683 | */ | |
684 | for(i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
685 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
686 | console_cmdline[i].index == idx) { | |
687 | selected_console = i; | |
688 | return 0; | |
689 | } | |
690 | if (i == MAX_CMDLINECONSOLES) | |
691 | return -E2BIG; | |
692 | selected_console = i; | |
693 | c = &console_cmdline[i]; | |
694 | memcpy(c->name, name, sizeof(c->name)); | |
695 | c->name[sizeof(c->name) - 1] = 0; | |
696 | c->options = options; | |
697 | c->index = idx; | |
698 | return 0; | |
699 | } | |
700 | ||
1da177e4 LT |
701 | /** |
702 | * acquire_console_sem - lock the console system for exclusive use. | |
703 | * | |
704 | * Acquires a semaphore which guarantees that the caller has | |
705 | * exclusive access to the console system and the console_drivers list. | |
706 | * | |
707 | * Can sleep, returns nothing. | |
708 | */ | |
709 | void acquire_console_sem(void) | |
710 | { | |
711 | if (in_interrupt()) | |
712 | BUG(); | |
713 | down(&console_sem); | |
714 | console_locked = 1; | |
715 | console_may_schedule = 1; | |
716 | } | |
717 | EXPORT_SYMBOL(acquire_console_sem); | |
718 | ||
719 | int try_acquire_console_sem(void) | |
720 | { | |
721 | if (down_trylock(&console_sem)) | |
722 | return -1; | |
723 | console_locked = 1; | |
724 | console_may_schedule = 0; | |
725 | return 0; | |
726 | } | |
727 | EXPORT_SYMBOL(try_acquire_console_sem); | |
728 | ||
729 | int is_console_locked(void) | |
730 | { | |
731 | return console_locked; | |
732 | } | |
733 | EXPORT_SYMBOL(is_console_locked); | |
734 | ||
735 | /** | |
736 | * release_console_sem - unlock the console system | |
737 | * | |
738 | * Releases the semaphore which the caller holds on the console system | |
739 | * and the console driver list. | |
740 | * | |
741 | * While the semaphore was held, console output may have been buffered | |
742 | * by printk(). If this is the case, release_console_sem() emits | |
743 | * the output prior to releasing the semaphore. | |
744 | * | |
745 | * If there is output waiting for klogd, we wake it up. | |
746 | * | |
747 | * release_console_sem() may be called from any context. | |
748 | */ | |
749 | void release_console_sem(void) | |
750 | { | |
751 | unsigned long flags; | |
752 | unsigned long _con_start, _log_end; | |
753 | unsigned long wake_klogd = 0; | |
754 | ||
755 | for ( ; ; ) { | |
756 | spin_lock_irqsave(&logbuf_lock, flags); | |
757 | wake_klogd |= log_start - log_end; | |
758 | if (con_start == log_end) | |
759 | break; /* Nothing to print */ | |
760 | _con_start = con_start; | |
761 | _log_end = log_end; | |
762 | con_start = log_end; /* Flush */ | |
763 | spin_unlock(&logbuf_lock); | |
764 | call_console_drivers(_con_start, _log_end); | |
765 | local_irq_restore(flags); | |
766 | } | |
767 | console_locked = 0; | |
768 | console_may_schedule = 0; | |
769 | up(&console_sem); | |
770 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
771 | if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait)) | |
772 | wake_up_interruptible(&log_wait); | |
773 | } | |
774 | EXPORT_SYMBOL(release_console_sem); | |
775 | ||
ddad86c2 MW |
776 | /** |
777 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
778 | * |
779 | * If the console code is currently allowed to sleep, and | |
780 | * if this CPU should yield the CPU to another task, do | |
781 | * so here. | |
782 | * | |
783 | * Must be called within acquire_console_sem(). | |
784 | */ | |
785 | void __sched console_conditional_schedule(void) | |
786 | { | |
787 | if (console_may_schedule) | |
788 | cond_resched(); | |
789 | } | |
790 | EXPORT_SYMBOL(console_conditional_schedule); | |
791 | ||
792 | void console_print(const char *s) | |
793 | { | |
794 | printk(KERN_EMERG "%s", s); | |
795 | } | |
796 | EXPORT_SYMBOL(console_print); | |
797 | ||
798 | void console_unblank(void) | |
799 | { | |
800 | struct console *c; | |
801 | ||
802 | /* | |
803 | * console_unblank can no longer be called in interrupt context unless | |
804 | * oops_in_progress is set to 1.. | |
805 | */ | |
806 | if (oops_in_progress) { | |
807 | if (down_trylock(&console_sem) != 0) | |
808 | return; | |
809 | } else | |
810 | acquire_console_sem(); | |
811 | ||
812 | console_locked = 1; | |
813 | console_may_schedule = 0; | |
814 | for (c = console_drivers; c != NULL; c = c->next) | |
815 | if ((c->flags & CON_ENABLED) && c->unblank) | |
816 | c->unblank(); | |
817 | release_console_sem(); | |
818 | } | |
1da177e4 LT |
819 | |
820 | /* | |
821 | * Return the console tty driver structure and its associated index | |
822 | */ | |
823 | struct tty_driver *console_device(int *index) | |
824 | { | |
825 | struct console *c; | |
826 | struct tty_driver *driver = NULL; | |
827 | ||
828 | acquire_console_sem(); | |
829 | for (c = console_drivers; c != NULL; c = c->next) { | |
830 | if (!c->device) | |
831 | continue; | |
832 | driver = c->device(c, index); | |
833 | if (driver) | |
834 | break; | |
835 | } | |
836 | release_console_sem(); | |
837 | return driver; | |
838 | } | |
839 | ||
840 | /* | |
841 | * Prevent further output on the passed console device so that (for example) | |
842 | * serial drivers can disable console output before suspending a port, and can | |
843 | * re-enable output afterwards. | |
844 | */ | |
845 | void console_stop(struct console *console) | |
846 | { | |
847 | acquire_console_sem(); | |
848 | console->flags &= ~CON_ENABLED; | |
849 | release_console_sem(); | |
850 | } | |
851 | EXPORT_SYMBOL(console_stop); | |
852 | ||
853 | void console_start(struct console *console) | |
854 | { | |
855 | acquire_console_sem(); | |
856 | console->flags |= CON_ENABLED; | |
857 | release_console_sem(); | |
858 | } | |
859 | EXPORT_SYMBOL(console_start); | |
860 | ||
861 | /* | |
862 | * The console driver calls this routine during kernel initialization | |
863 | * to register the console printing procedure with printk() and to | |
864 | * print any messages that were printed by the kernel before the | |
865 | * console driver was initialized. | |
866 | */ | |
40dc5651 | 867 | void register_console(struct console *console) |
1da177e4 | 868 | { |
40dc5651 | 869 | int i; |
1da177e4 LT |
870 | unsigned long flags; |
871 | ||
872 | if (preferred_console < 0) | |
873 | preferred_console = selected_console; | |
874 | ||
875 | /* | |
876 | * See if we want to use this console driver. If we | |
877 | * didn't select a console we take the first one | |
878 | * that registers here. | |
879 | */ | |
880 | if (preferred_console < 0) { | |
881 | if (console->index < 0) | |
882 | console->index = 0; | |
883 | if (console->setup == NULL || | |
884 | console->setup(console, NULL) == 0) { | |
885 | console->flags |= CON_ENABLED | CON_CONSDEV; | |
886 | preferred_console = 0; | |
887 | } | |
888 | } | |
889 | ||
890 | /* | |
891 | * See if this console matches one we selected on | |
892 | * the command line. | |
893 | */ | |
40dc5651 JJ |
894 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
895 | i++) { | |
1da177e4 LT |
896 | if (strcmp(console_cmdline[i].name, console->name) != 0) |
897 | continue; | |
898 | if (console->index >= 0 && | |
899 | console->index != console_cmdline[i].index) | |
900 | continue; | |
901 | if (console->index < 0) | |
902 | console->index = console_cmdline[i].index; | |
903 | if (console->setup && | |
904 | console->setup(console, console_cmdline[i].options) != 0) | |
905 | break; | |
906 | console->flags |= CON_ENABLED; | |
907 | console->index = console_cmdline[i].index; | |
ab4af03a | 908 | if (i == selected_console) { |
1da177e4 | 909 | console->flags |= CON_CONSDEV; |
ab4af03a GE |
910 | preferred_console = selected_console; |
911 | } | |
1da177e4 LT |
912 | break; |
913 | } | |
914 | ||
915 | if (!(console->flags & CON_ENABLED)) | |
916 | return; | |
917 | ||
918 | if (console_drivers && (console_drivers->flags & CON_BOOT)) { | |
919 | unregister_console(console_drivers); | |
920 | console->flags &= ~CON_PRINTBUFFER; | |
921 | } | |
922 | ||
923 | /* | |
924 | * Put this console in the list - keep the | |
925 | * preferred driver at the head of the list. | |
926 | */ | |
927 | acquire_console_sem(); | |
928 | if ((console->flags & CON_CONSDEV) || console_drivers == NULL) { | |
929 | console->next = console_drivers; | |
930 | console_drivers = console; | |
ab4af03a GE |
931 | if (console->next) |
932 | console->next->flags &= ~CON_CONSDEV; | |
1da177e4 LT |
933 | } else { |
934 | console->next = console_drivers->next; | |
935 | console_drivers->next = console; | |
936 | } | |
937 | if (console->flags & CON_PRINTBUFFER) { | |
938 | /* | |
939 | * release_console_sem() will print out the buffered messages | |
940 | * for us. | |
941 | */ | |
942 | spin_lock_irqsave(&logbuf_lock, flags); | |
943 | con_start = log_start; | |
944 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
945 | } | |
946 | release_console_sem(); | |
947 | } | |
948 | EXPORT_SYMBOL(register_console); | |
949 | ||
40dc5651 | 950 | int unregister_console(struct console *console) |
1da177e4 | 951 | { |
40dc5651 | 952 | struct console *a, *b; |
1da177e4 LT |
953 | int res = 1; |
954 | ||
955 | acquire_console_sem(); | |
956 | if (console_drivers == console) { | |
957 | console_drivers=console->next; | |
958 | res = 0; | |
e9b15b54 | 959 | } else if (console_drivers) { |
1da177e4 LT |
960 | for (a=console_drivers->next, b=console_drivers ; |
961 | a; b=a, a=b->next) { | |
962 | if (a == console) { | |
963 | b->next = a->next; | |
964 | res = 0; | |
965 | break; | |
40dc5651 | 966 | } |
1da177e4 LT |
967 | } |
968 | } | |
40dc5651 | 969 | |
1da177e4 LT |
970 | /* If last console is removed, we re-enable picking the first |
971 | * one that gets registered. Without that, pmac early boot console | |
972 | * would prevent fbcon from taking over. | |
ab4af03a GE |
973 | * |
974 | * If this isn't the last console and it has CON_CONSDEV set, we | |
975 | * need to set it on the next preferred console. | |
1da177e4 LT |
976 | */ |
977 | if (console_drivers == NULL) | |
978 | preferred_console = selected_console; | |
ab4af03a GE |
979 | else if (console->flags & CON_CONSDEV) |
980 | console_drivers->flags |= CON_CONSDEV; | |
1da177e4 LT |
981 | |
982 | release_console_sem(); | |
983 | return res; | |
984 | } | |
985 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 986 | |
1da177e4 LT |
987 | /** |
988 | * tty_write_message - write a message to a certain tty, not just the console. | |
ddad86c2 MW |
989 | * @tty: the destination tty_struct |
990 | * @msg: the message to write | |
1da177e4 LT |
991 | * |
992 | * This is used for messages that need to be redirected to a specific tty. | |
993 | * We don't put it into the syslog queue right now maybe in the future if | |
994 | * really needed. | |
995 | */ | |
996 | void tty_write_message(struct tty_struct *tty, char *msg) | |
997 | { | |
998 | if (tty && tty->driver->write) | |
999 | tty->driver->write(tty, msg, strlen(msg)); | |
1000 | return; | |
1001 | } | |
1002 | ||
1003 | /* | |
1004 | * printk rate limiting, lifted from the networking subsystem. | |
1005 | * | |
1006 | * This enforces a rate limit: not more than one kernel message | |
1007 | * every printk_ratelimit_jiffies to make a denial-of-service | |
1008 | * attack impossible. | |
1009 | */ | |
1010 | int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst) | |
1011 | { | |
1012 | static DEFINE_SPINLOCK(ratelimit_lock); | |
40dc5651 | 1013 | static unsigned long toks = 10 * 5 * HZ; |
1da177e4 LT |
1014 | static unsigned long last_msg; |
1015 | static int missed; | |
1016 | unsigned long flags; | |
1017 | unsigned long now = jiffies; | |
1018 | ||
1019 | spin_lock_irqsave(&ratelimit_lock, flags); | |
1020 | toks += now - last_msg; | |
1021 | last_msg = now; | |
1022 | if (toks > (ratelimit_burst * ratelimit_jiffies)) | |
1023 | toks = ratelimit_burst * ratelimit_jiffies; | |
1024 | if (toks >= ratelimit_jiffies) { | |
1025 | int lost = missed; | |
40dc5651 | 1026 | |
1da177e4 LT |
1027 | missed = 0; |
1028 | toks -= ratelimit_jiffies; | |
1029 | spin_unlock_irqrestore(&ratelimit_lock, flags); | |
1030 | if (lost) | |
1031 | printk(KERN_WARNING "printk: %d messages suppressed.\n", lost); | |
1032 | return 1; | |
1033 | } | |
1034 | missed++; | |
1035 | spin_unlock_irqrestore(&ratelimit_lock, flags); | |
1036 | return 0; | |
1037 | } | |
1038 | EXPORT_SYMBOL(__printk_ratelimit); | |
1039 | ||
1040 | /* minimum time in jiffies between messages */ | |
40dc5651 | 1041 | int printk_ratelimit_jiffies = 5 * HZ; |
1da177e4 LT |
1042 | |
1043 | /* number of messages we send before ratelimiting */ | |
1044 | int printk_ratelimit_burst = 10; | |
1045 | ||
1046 | int printk_ratelimit(void) | |
1047 | { | |
1048 | return __printk_ratelimit(printk_ratelimit_jiffies, | |
1049 | printk_ratelimit_burst); | |
1050 | } | |
1051 | EXPORT_SYMBOL(printk_ratelimit); |