]>
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> | |
1da177e4 LT |
23 | #include <linux/console.h> |
24 | #include <linux/init.h> | |
25 | #include <linux/module.h> | |
3b9c0410 | 26 | #include <linux/moduleparam.h> |
1da177e4 | 27 | #include <linux/interrupt.h> /* For in_interrupt() */ |
1da177e4 LT |
28 | #include <linux/delay.h> |
29 | #include <linux/smp.h> | |
30 | #include <linux/security.h> | |
31 | #include <linux/bootmem.h> | |
32 | #include <linux/syscalls.h> | |
f46c4833 | 33 | #include <linux/jiffies.h> |
1da177e4 LT |
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 | ||
1da177e4 | 55 | /* |
0bbfb7c2 | 56 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
57 | * their unblank() callback or not. So let's export it. |
58 | */ | |
59 | int oops_in_progress; | |
60 | EXPORT_SYMBOL(oops_in_progress); | |
61 | ||
62 | /* | |
63 | * console_sem protects the console_drivers list, and also | |
64 | * provides serialisation for access to the entire console | |
65 | * driver system. | |
66 | */ | |
67 | static DECLARE_MUTEX(console_sem); | |
557240b4 | 68 | static DECLARE_MUTEX(secondary_console_sem); |
1da177e4 LT |
69 | struct console *console_drivers; |
70 | /* | |
71 | * This is used for debugging the mess that is the VT code by | |
72 | * keeping track if we have the console semaphore held. It's | |
73 | * definitely not the perfect debug tool (we don't know if _WE_ | |
74 | * hold it are racing, but it helps tracking those weird code | |
75 | * path in the console code where we end up in places I want | |
76 | * locked without the console sempahore held | |
77 | */ | |
557240b4 | 78 | static int console_locked, console_suspended; |
1da177e4 LT |
79 | |
80 | /* | |
81 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
82 | * It is also used in interesting ways to provide interlocking in | |
83 | * release_console_sem(). | |
84 | */ | |
85 | static DEFINE_SPINLOCK(logbuf_lock); | |
86 | ||
1da177e4 LT |
87 | #define LOG_BUF_MASK (log_buf_len-1) |
88 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) | |
89 | ||
90 | /* | |
91 | * The indices into log_buf are not constrained to log_buf_len - they | |
92 | * must be masked before subscripting | |
93 | */ | |
94 | static unsigned long log_start; /* Index into log_buf: next char to be read by syslog() */ | |
95 | static unsigned long con_start; /* Index into log_buf: next char to be sent to consoles */ | |
96 | static unsigned long log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
97 | |
98 | /* | |
99 | * Array of consoles built from command line options (console=) | |
100 | */ | |
101 | struct console_cmdline | |
102 | { | |
103 | char name[8]; /* Name of the driver */ | |
104 | int index; /* Minor dev. to use */ | |
105 | char *options; /* Options for the driver */ | |
106 | }; | |
107 | ||
108 | #define MAX_CMDLINECONSOLES 8 | |
109 | ||
110 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
111 | static int selected_console = -1; | |
112 | static int preferred_console = -1; | |
113 | ||
114 | /* Flag: console code may call schedule() */ | |
115 | static int console_may_schedule; | |
116 | ||
d59745ce MM |
117 | #ifdef CONFIG_PRINTK |
118 | ||
119 | static char __log_buf[__LOG_BUF_LEN]; | |
120 | static char *log_buf = __log_buf; | |
121 | static int log_buf_len = __LOG_BUF_LEN; | |
122 | static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */ | |
123 | ||
1da177e4 LT |
124 | static int __init log_buf_len_setup(char *str) |
125 | { | |
126 | unsigned long size = memparse(str, &str); | |
127 | unsigned long flags; | |
128 | ||
129 | if (size) | |
130 | size = roundup_pow_of_two(size); | |
131 | if (size > log_buf_len) { | |
132 | unsigned long start, dest_idx, offset; | |
40dc5651 | 133 | char *new_log_buf; |
1da177e4 LT |
134 | |
135 | new_log_buf = alloc_bootmem(size); | |
136 | if (!new_log_buf) { | |
40dc5651 | 137 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
138 | goto out; |
139 | } | |
140 | ||
141 | spin_lock_irqsave(&logbuf_lock, flags); | |
142 | log_buf_len = size; | |
143 | log_buf = new_log_buf; | |
144 | ||
145 | offset = start = min(con_start, log_start); | |
146 | dest_idx = 0; | |
147 | while (start != log_end) { | |
148 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
149 | start++; | |
150 | dest_idx++; | |
151 | } | |
152 | log_start -= offset; | |
153 | con_start -= offset; | |
154 | log_end -= offset; | |
155 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
156 | ||
40dc5651 | 157 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
158 | } |
159 | out: | |
1da177e4 LT |
160 | return 1; |
161 | } | |
162 | ||
163 | __setup("log_buf_len=", log_buf_len_setup); | |
164 | ||
165 | /* | |
166 | * Commands to do_syslog: | |
167 | * | |
168 | * 0 -- Close the log. Currently a NOP. | |
169 | * 1 -- Open the log. Currently a NOP. | |
170 | * 2 -- Read from the log. | |
171 | * 3 -- Read all messages remaining in the ring buffer. | |
172 | * 4 -- Read and clear all messages remaining in the ring buffer | |
173 | * 5 -- Clear ring buffer. | |
174 | * 6 -- Disable printk's to console | |
175 | * 7 -- Enable printk's to console | |
176 | * 8 -- Set level of messages printed to console | |
177 | * 9 -- Return number of unread characters in the log buffer | |
178 | * 10 -- Return size of the log buffer | |
179 | */ | |
40dc5651 | 180 | int do_syslog(int type, char __user *buf, int len) |
1da177e4 LT |
181 | { |
182 | unsigned long i, j, limit, count; | |
183 | int do_clear = 0; | |
184 | char c; | |
185 | int error = 0; | |
186 | ||
187 | error = security_syslog(type); | |
188 | if (error) | |
189 | return error; | |
190 | ||
191 | switch (type) { | |
192 | case 0: /* Close log */ | |
193 | break; | |
194 | case 1: /* Open log */ | |
195 | break; | |
196 | case 2: /* Read from log */ | |
197 | error = -EINVAL; | |
198 | if (!buf || len < 0) | |
199 | goto out; | |
200 | error = 0; | |
201 | if (!len) | |
202 | goto out; | |
203 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
204 | error = -EFAULT; | |
205 | goto out; | |
206 | } | |
40dc5651 JJ |
207 | error = wait_event_interruptible(log_wait, |
208 | (log_start - log_end)); | |
1da177e4 LT |
209 | if (error) |
210 | goto out; | |
211 | i = 0; | |
212 | spin_lock_irq(&logbuf_lock); | |
213 | while (!error && (log_start != log_end) && i < len) { | |
214 | c = LOG_BUF(log_start); | |
215 | log_start++; | |
216 | spin_unlock_irq(&logbuf_lock); | |
217 | error = __put_user(c,buf); | |
218 | buf++; | |
219 | i++; | |
220 | cond_resched(); | |
221 | spin_lock_irq(&logbuf_lock); | |
222 | } | |
223 | spin_unlock_irq(&logbuf_lock); | |
224 | if (!error) | |
225 | error = i; | |
226 | break; | |
227 | case 4: /* Read/clear last kernel messages */ | |
40dc5651 | 228 | do_clear = 1; |
1da177e4 LT |
229 | /* FALL THRU */ |
230 | case 3: /* Read last kernel messages */ | |
231 | error = -EINVAL; | |
232 | if (!buf || len < 0) | |
233 | goto out; | |
234 | error = 0; | |
235 | if (!len) | |
236 | goto out; | |
237 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
238 | error = -EFAULT; | |
239 | goto out; | |
240 | } | |
241 | count = len; | |
242 | if (count > log_buf_len) | |
243 | count = log_buf_len; | |
244 | spin_lock_irq(&logbuf_lock); | |
245 | if (count > logged_chars) | |
246 | count = logged_chars; | |
247 | if (do_clear) | |
248 | logged_chars = 0; | |
249 | limit = log_end; | |
250 | /* | |
251 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 252 | * printk() could overwrite the messages |
1da177e4 LT |
253 | * we try to copy to user space. Therefore |
254 | * the messages are copied in reverse. <manfreds> | |
255 | */ | |
40dc5651 | 256 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
257 | j = limit-1-i; |
258 | if (j + log_buf_len < log_end) | |
259 | break; | |
260 | c = LOG_BUF(j); | |
261 | spin_unlock_irq(&logbuf_lock); | |
262 | error = __put_user(c,&buf[count-1-i]); | |
263 | cond_resched(); | |
264 | spin_lock_irq(&logbuf_lock); | |
265 | } | |
266 | spin_unlock_irq(&logbuf_lock); | |
267 | if (error) | |
268 | break; | |
269 | error = i; | |
40dc5651 | 270 | if (i != count) { |
1da177e4 LT |
271 | int offset = count-error; |
272 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 273 | for (i = 0; i < error; i++) { |
1da177e4 LT |
274 | if (__get_user(c,&buf[i+offset]) || |
275 | __put_user(c,&buf[i])) { | |
276 | error = -EFAULT; | |
277 | break; | |
278 | } | |
279 | cond_resched(); | |
280 | } | |
281 | } | |
282 | break; | |
283 | case 5: /* Clear ring buffer */ | |
284 | logged_chars = 0; | |
285 | break; | |
286 | case 6: /* Disable logging to console */ | |
287 | console_loglevel = minimum_console_loglevel; | |
288 | break; | |
289 | case 7: /* Enable logging to console */ | |
290 | console_loglevel = default_console_loglevel; | |
291 | break; | |
292 | case 8: /* Set level of messages printed to console */ | |
293 | error = -EINVAL; | |
294 | if (len < 1 || len > 8) | |
295 | goto out; | |
296 | if (len < minimum_console_loglevel) | |
297 | len = minimum_console_loglevel; | |
298 | console_loglevel = len; | |
299 | error = 0; | |
300 | break; | |
301 | case 9: /* Number of chars in the log buffer */ | |
302 | error = log_end - log_start; | |
303 | break; | |
304 | case 10: /* Size of the log buffer */ | |
305 | error = log_buf_len; | |
306 | break; | |
307 | default: | |
308 | error = -EINVAL; | |
309 | break; | |
310 | } | |
311 | out: | |
312 | return error; | |
313 | } | |
314 | ||
40dc5651 | 315 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
1da177e4 LT |
316 | { |
317 | return do_syslog(type, buf, len); | |
318 | } | |
319 | ||
320 | /* | |
321 | * Call the console drivers on a range of log_buf | |
322 | */ | |
323 | static void __call_console_drivers(unsigned long start, unsigned long end) | |
324 | { | |
325 | struct console *con; | |
326 | ||
327 | for (con = console_drivers; con; con = con->next) { | |
76a8ad29 ME |
328 | if ((con->flags & CON_ENABLED) && con->write && |
329 | (cpu_online(smp_processor_id()) || | |
330 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
331 | con->write(con, &LOG_BUF(start), end - start); |
332 | } | |
333 | } | |
334 | ||
79290822 IM |
335 | static int __read_mostly ignore_loglevel; |
336 | ||
99eea6a1 | 337 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
338 | { |
339 | ignore_loglevel = 1; | |
340 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
341 | ||
342 | return 1; | |
343 | } | |
344 | ||
345 | __setup("ignore_loglevel", ignore_loglevel_setup); | |
346 | ||
1da177e4 LT |
347 | /* |
348 | * Write out chars from start to end - 1 inclusive | |
349 | */ | |
350 | static void _call_console_drivers(unsigned long start, | |
351 | unsigned long end, int msg_log_level) | |
352 | { | |
79290822 | 353 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
354 | console_drivers && start != end) { |
355 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
356 | /* wrapped write */ | |
357 | __call_console_drivers(start & LOG_BUF_MASK, | |
358 | log_buf_len); | |
359 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
360 | } else { | |
361 | __call_console_drivers(start, end); | |
362 | } | |
363 | } | |
364 | } | |
365 | ||
366 | /* | |
367 | * Call the console drivers, asking them to write out | |
368 | * log_buf[start] to log_buf[end - 1]. | |
369 | * The console_sem must be held. | |
370 | */ | |
371 | static void call_console_drivers(unsigned long start, unsigned long end) | |
372 | { | |
373 | unsigned long cur_index, start_print; | |
374 | static int msg_level = -1; | |
375 | ||
8abd8e29 | 376 | BUG_ON(((long)(start - end)) > 0); |
1da177e4 LT |
377 | |
378 | cur_index = start; | |
379 | start_print = start; | |
380 | while (cur_index != end) { | |
40dc5651 JJ |
381 | if (msg_level < 0 && ((end - cur_index) > 2) && |
382 | LOG_BUF(cur_index + 0) == '<' && | |
383 | LOG_BUF(cur_index + 1) >= '0' && | |
384 | LOG_BUF(cur_index + 1) <= '7' && | |
385 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
386 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
387 | cur_index += 3; | |
388 | start_print = cur_index; | |
389 | } | |
390 | while (cur_index != end) { | |
391 | char c = LOG_BUF(cur_index); | |
1da177e4 | 392 | |
40dc5651 | 393 | cur_index++; |
1da177e4 LT |
394 | if (c == '\n') { |
395 | if (msg_level < 0) { | |
396 | /* | |
397 | * printk() has already given us loglevel tags in | |
398 | * the buffer. This code is here in case the | |
399 | * log buffer has wrapped right round and scribbled | |
400 | * on those tags | |
401 | */ | |
402 | msg_level = default_message_loglevel; | |
403 | } | |
404 | _call_console_drivers(start_print, cur_index, msg_level); | |
405 | msg_level = -1; | |
406 | start_print = cur_index; | |
407 | break; | |
408 | } | |
409 | } | |
410 | } | |
411 | _call_console_drivers(start_print, end, msg_level); | |
412 | } | |
413 | ||
414 | static void emit_log_char(char c) | |
415 | { | |
416 | LOG_BUF(log_end) = c; | |
417 | log_end++; | |
418 | if (log_end - log_start > log_buf_len) | |
419 | log_start = log_end - log_buf_len; | |
420 | if (log_end - con_start > log_buf_len) | |
421 | con_start = log_end - log_buf_len; | |
422 | if (logged_chars < log_buf_len) | |
423 | logged_chars++; | |
424 | } | |
425 | ||
426 | /* | |
427 | * Zap console related locks when oopsing. Only zap at most once | |
428 | * every 10 seconds, to leave time for slow consoles to print a | |
429 | * full oops. | |
430 | */ | |
431 | static void zap_locks(void) | |
432 | { | |
433 | static unsigned long oops_timestamp; | |
434 | ||
435 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 436 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
437 | return; |
438 | ||
439 | oops_timestamp = jiffies; | |
440 | ||
441 | /* If a crash is occurring, make sure we can't deadlock */ | |
442 | spin_lock_init(&logbuf_lock); | |
443 | /* And make sure that we print immediately */ | |
444 | init_MUTEX(&console_sem); | |
445 | } | |
446 | ||
447 | #if defined(CONFIG_PRINTK_TIME) | |
448 | static int printk_time = 1; | |
449 | #else | |
450 | static int printk_time = 0; | |
451 | #endif | |
3b9c0410 | 452 | module_param(printk_time, int, S_IRUGO | S_IWUSR); |
1da177e4 LT |
453 | |
454 | static int __init printk_time_setup(char *str) | |
455 | { | |
456 | if (*str) | |
457 | return 0; | |
458 | printk_time = 1; | |
459 | return 1; | |
460 | } | |
461 | ||
462 | __setup("time", printk_time_setup); | |
463 | ||
31f6d9d6 AM |
464 | __attribute__((weak)) unsigned long long printk_clock(void) |
465 | { | |
466 | return sched_clock(); | |
467 | } | |
468 | ||
76a8ad29 ME |
469 | /* Check if we have any console registered that can be called early in boot. */ |
470 | static int have_callable_console(void) | |
471 | { | |
472 | struct console *con; | |
473 | ||
474 | for (con = console_drivers; con; con = con->next) | |
475 | if (con->flags & CON_ANYTIME) | |
476 | return 1; | |
477 | ||
478 | return 0; | |
479 | } | |
480 | ||
ddad86c2 MW |
481 | /** |
482 | * printk - print a kernel message | |
483 | * @fmt: format string | |
484 | * | |
72fd4a35 | 485 | * This is printk(). It can be called from any context. We want it to work. |
40dc5651 | 486 | * |
1da177e4 LT |
487 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
488 | * call the console drivers. If we fail to get the semaphore we place the output | |
489 | * into the log buffer and return. The current holder of the console_sem will | |
490 | * notice the new output in release_console_sem() and will send it to the | |
491 | * consoles before releasing the semaphore. | |
492 | * | |
493 | * One effect of this deferred printing is that code which calls printk() and | |
494 | * then changes console_loglevel may break. This is because console_loglevel | |
495 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
496 | * |
497 | * See also: | |
498 | * printf(3) | |
1da177e4 | 499 | */ |
d59745ce | 500 | |
1da177e4 LT |
501 | asmlinkage int printk(const char *fmt, ...) |
502 | { | |
503 | va_list args; | |
504 | int r; | |
505 | ||
506 | va_start(args, fmt); | |
507 | r = vprintk(fmt, args); | |
508 | va_end(args); | |
509 | ||
510 | return r; | |
511 | } | |
512 | ||
fe21773d DH |
513 | /* cpu currently holding logbuf_lock */ |
514 | static volatile unsigned int printk_cpu = UINT_MAX; | |
515 | ||
1da177e4 LT |
516 | asmlinkage int vprintk(const char *fmt, va_list args) |
517 | { | |
518 | unsigned long flags; | |
519 | int printed_len; | |
520 | char *p; | |
521 | static char printk_buf[1024]; | |
522 | static int log_level_unknown = 1; | |
523 | ||
fe21773d DH |
524 | preempt_disable(); |
525 | if (unlikely(oops_in_progress) && printk_cpu == smp_processor_id()) | |
526 | /* If a crash is occurring during printk() on this CPU, | |
527 | * make sure we can't deadlock */ | |
1da177e4 LT |
528 | zap_locks(); |
529 | ||
530 | /* This stops the holder of console_sem just where we want him */ | |
1efc5da3 | 531 | raw_local_irq_save(flags); |
a0f1ccfd IM |
532 | lockdep_off(); |
533 | spin_lock(&logbuf_lock); | |
fe21773d | 534 | printk_cpu = smp_processor_id(); |
1da177e4 LT |
535 | |
536 | /* Emit the output into the temporary buffer */ | |
537 | printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args); | |
538 | ||
539 | /* | |
540 | * Copy the output into log_buf. If the caller didn't provide | |
541 | * appropriate log level tags, we insert them here | |
542 | */ | |
543 | for (p = printk_buf; *p; p++) { | |
544 | if (log_level_unknown) { | |
545 | /* log_level_unknown signals the start of a new line */ | |
546 | if (printk_time) { | |
547 | int loglev_char; | |
548 | char tbuf[50], *tp; | |
549 | unsigned tlen; | |
550 | unsigned long long t; | |
551 | unsigned long nanosec_rem; | |
552 | ||
553 | /* | |
554 | * force the log level token to be | |
555 | * before the time output. | |
556 | */ | |
557 | if (p[0] == '<' && p[1] >='0' && | |
558 | p[1] <= '7' && p[2] == '>') { | |
559 | loglev_char = p[1]; | |
560 | p += 3; | |
025510cd | 561 | printed_len -= 3; |
1da177e4 LT |
562 | } else { |
563 | loglev_char = default_message_loglevel | |
564 | + '0'; | |
565 | } | |
31f6d9d6 | 566 | t = printk_clock(); |
1da177e4 LT |
567 | nanosec_rem = do_div(t, 1000000000); |
568 | tlen = sprintf(tbuf, | |
569 | "<%c>[%5lu.%06lu] ", | |
570 | loglev_char, | |
571 | (unsigned long)t, | |
572 | nanosec_rem/1000); | |
573 | ||
574 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
575 | emit_log_char(*tp); | |
025510cd | 576 | printed_len += tlen; |
1da177e4 LT |
577 | } else { |
578 | if (p[0] != '<' || p[1] < '0' || | |
579 | p[1] > '7' || p[2] != '>') { | |
580 | emit_log_char('<'); | |
581 | emit_log_char(default_message_loglevel | |
582 | + '0'); | |
583 | emit_log_char('>'); | |
025510cd | 584 | printed_len += 3; |
1da177e4 | 585 | } |
1da177e4 LT |
586 | } |
587 | log_level_unknown = 0; | |
588 | if (!*p) | |
589 | break; | |
590 | } | |
591 | emit_log_char(*p); | |
592 | if (*p == '\n') | |
593 | log_level_unknown = 1; | |
594 | } | |
595 | ||
76a8ad29 | 596 | if (!down_trylock(&console_sem)) { |
1da177e4 | 597 | /* |
76a8ad29 ME |
598 | * We own the drivers. We can drop the spinlock and |
599 | * let release_console_sem() print the text, maybe ... | |
1da177e4 | 600 | */ |
76a8ad29 | 601 | console_locked = 1; |
fe21773d | 602 | printk_cpu = UINT_MAX; |
a0f1ccfd | 603 | spin_unlock(&logbuf_lock); |
76a8ad29 | 604 | |
1da177e4 | 605 | /* |
76a8ad29 ME |
606 | * Console drivers may assume that per-cpu resources have |
607 | * been allocated. So unless they're explicitly marked as | |
608 | * being able to cope (CON_ANYTIME) don't call them until | |
609 | * this CPU is officially up. | |
1da177e4 | 610 | */ |
76a8ad29 ME |
611 | if (cpu_online(smp_processor_id()) || have_callable_console()) { |
612 | console_may_schedule = 0; | |
613 | release_console_sem(); | |
614 | } else { | |
615 | /* Release by hand to avoid flushing the buffer. */ | |
616 | console_locked = 0; | |
617 | up(&console_sem); | |
618 | } | |
a0f1ccfd | 619 | lockdep_on(); |
1efc5da3 | 620 | raw_local_irq_restore(flags); |
1da177e4 LT |
621 | } else { |
622 | /* | |
623 | * Someone else owns the drivers. We drop the spinlock, which | |
624 | * allows the semaphore holder to proceed and to call the | |
625 | * console drivers with the output which we just produced. | |
626 | */ | |
fe21773d | 627 | printk_cpu = UINT_MAX; |
a0f1ccfd IM |
628 | spin_unlock(&logbuf_lock); |
629 | lockdep_on(); | |
1efc5da3 | 630 | raw_local_irq_restore(flags); |
1da177e4 | 631 | } |
76a8ad29 | 632 | |
fe21773d | 633 | preempt_enable(); |
1da177e4 LT |
634 | return printed_len; |
635 | } | |
636 | EXPORT_SYMBOL(printk); | |
637 | EXPORT_SYMBOL(vprintk); | |
638 | ||
d59745ce MM |
639 | #else |
640 | ||
40dc5651 | 641 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
d59745ce | 642 | { |
c36264df | 643 | return -ENOSYS; |
40dc5651 JJ |
644 | } |
645 | ||
646 | static void call_console_drivers(unsigned long start, unsigned long end) | |
647 | { | |
648 | } | |
d59745ce MM |
649 | |
650 | #endif | |
651 | ||
2ea1c539 JB |
652 | /* |
653 | * Set up a list of consoles. Called from init/main.c | |
654 | */ | |
655 | static int __init console_setup(char *str) | |
656 | { | |
eaa944af | 657 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
2ea1c539 JB |
658 | char *s, *options; |
659 | int idx; | |
660 | ||
661 | /* | |
662 | * Decode str into name, index, options. | |
663 | */ | |
664 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
665 | strcpy(buf, "ttyS"); |
666 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 667 | } else { |
eaa944af | 668 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 669 | } |
eaa944af | 670 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
671 | if ((options = strchr(str, ',')) != NULL) |
672 | *(options++) = 0; | |
673 | #ifdef __sparc__ | |
674 | if (!strcmp(str, "ttya")) | |
eaa944af | 675 | strcpy(buf, "ttyS0"); |
2ea1c539 | 676 | if (!strcmp(str, "ttyb")) |
eaa944af | 677 | strcpy(buf, "ttyS1"); |
2ea1c539 | 678 | #endif |
eaa944af | 679 | for (s = buf; *s; s++) |
2ea1c539 JB |
680 | if ((*s >= '0' && *s <= '9') || *s == ',') |
681 | break; | |
682 | idx = simple_strtoul(s, NULL, 10); | |
683 | *s = 0; | |
684 | ||
eaa944af | 685 | add_preferred_console(buf, idx, options); |
2ea1c539 JB |
686 | return 1; |
687 | } | |
688 | __setup("console=", console_setup); | |
689 | ||
3c0547ba MM |
690 | /** |
691 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
692 | * @name: device name |
693 | * @idx: device index | |
694 | * @options: options for this console | |
3c0547ba MM |
695 | * |
696 | * The last preferred console added will be used for kernel messages | |
697 | * and stdin/out/err for init. Normally this is used by console_setup | |
698 | * above to handle user-supplied console arguments; however it can also | |
699 | * be used by arch-specific code either to override the user or more | |
700 | * commonly to provide a default console (ie from PROM variables) when | |
701 | * the user has not supplied one. | |
702 | */ | |
703 | int __init add_preferred_console(char *name, int idx, char *options) | |
704 | { | |
705 | struct console_cmdline *c; | |
706 | int i; | |
707 | ||
708 | /* | |
709 | * See if this tty is not yet registered, and | |
710 | * if we have a slot free. | |
711 | */ | |
eaa944af | 712 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
3c0547ba MM |
713 | if (strcmp(console_cmdline[i].name, name) == 0 && |
714 | console_cmdline[i].index == idx) { | |
715 | selected_console = i; | |
716 | return 0; | |
717 | } | |
718 | if (i == MAX_CMDLINECONSOLES) | |
719 | return -E2BIG; | |
720 | selected_console = i; | |
721 | c = &console_cmdline[i]; | |
722 | memcpy(c->name, name, sizeof(c->name)); | |
723 | c->name[sizeof(c->name) - 1] = 0; | |
724 | c->options = options; | |
725 | c->index = idx; | |
726 | return 0; | |
727 | } | |
728 | ||
c8eb8b40 | 729 | #ifndef CONFIG_DISABLE_CONSOLE_SUSPEND |
557240b4 LT |
730 | /** |
731 | * suspend_console - suspend the console subsystem | |
732 | * | |
733 | * This disables printk() while we go into suspend states | |
734 | */ | |
735 | void suspend_console(void) | |
736 | { | |
c8eb8b40 | 737 | printk("Suspending console(s)\n"); |
557240b4 LT |
738 | acquire_console_sem(); |
739 | console_suspended = 1; | |
740 | } | |
741 | ||
742 | void resume_console(void) | |
743 | { | |
744 | console_suspended = 0; | |
745 | release_console_sem(); | |
746 | } | |
c8eb8b40 | 747 | #endif /* CONFIG_DISABLE_CONSOLE_SUSPEND */ |
557240b4 | 748 | |
1da177e4 LT |
749 | /** |
750 | * acquire_console_sem - lock the console system for exclusive use. | |
751 | * | |
752 | * Acquires a semaphore which guarantees that the caller has | |
753 | * exclusive access to the console system and the console_drivers list. | |
754 | * | |
755 | * Can sleep, returns nothing. | |
756 | */ | |
757 | void acquire_console_sem(void) | |
758 | { | |
8abd8e29 | 759 | BUG_ON(in_interrupt()); |
557240b4 LT |
760 | if (console_suspended) { |
761 | down(&secondary_console_sem); | |
762 | return; | |
763 | } | |
1da177e4 LT |
764 | down(&console_sem); |
765 | console_locked = 1; | |
766 | console_may_schedule = 1; | |
767 | } | |
768 | EXPORT_SYMBOL(acquire_console_sem); | |
769 | ||
770 | int try_acquire_console_sem(void) | |
771 | { | |
772 | if (down_trylock(&console_sem)) | |
773 | return -1; | |
774 | console_locked = 1; | |
775 | console_may_schedule = 0; | |
776 | return 0; | |
777 | } | |
778 | EXPORT_SYMBOL(try_acquire_console_sem); | |
779 | ||
780 | int is_console_locked(void) | |
781 | { | |
782 | return console_locked; | |
783 | } | |
1da177e4 | 784 | |
e3e8a75d KK |
785 | void wake_up_klogd(void) |
786 | { | |
787 | if (!oops_in_progress && waitqueue_active(&log_wait)) | |
788 | wake_up_interruptible(&log_wait); | |
789 | } | |
790 | ||
1da177e4 LT |
791 | /** |
792 | * release_console_sem - unlock the console system | |
793 | * | |
794 | * Releases the semaphore which the caller holds on the console system | |
795 | * and the console driver list. | |
796 | * | |
797 | * While the semaphore was held, console output may have been buffered | |
798 | * by printk(). If this is the case, release_console_sem() emits | |
799 | * the output prior to releasing the semaphore. | |
800 | * | |
801 | * If there is output waiting for klogd, we wake it up. | |
802 | * | |
803 | * release_console_sem() may be called from any context. | |
804 | */ | |
805 | void release_console_sem(void) | |
806 | { | |
807 | unsigned long flags; | |
808 | unsigned long _con_start, _log_end; | |
809 | unsigned long wake_klogd = 0; | |
810 | ||
557240b4 LT |
811 | if (console_suspended) { |
812 | up(&secondary_console_sem); | |
813 | return; | |
814 | } | |
78944e54 AD |
815 | |
816 | console_may_schedule = 0; | |
817 | ||
1da177e4 LT |
818 | for ( ; ; ) { |
819 | spin_lock_irqsave(&logbuf_lock, flags); | |
820 | wake_klogd |= log_start - log_end; | |
821 | if (con_start == log_end) | |
822 | break; /* Nothing to print */ | |
823 | _con_start = con_start; | |
824 | _log_end = log_end; | |
825 | con_start = log_end; /* Flush */ | |
826 | spin_unlock(&logbuf_lock); | |
827 | call_console_drivers(_con_start, _log_end); | |
828 | local_irq_restore(flags); | |
829 | } | |
830 | console_locked = 0; | |
1da177e4 LT |
831 | up(&console_sem); |
832 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
833 | if (wake_klogd) |
834 | wake_up_klogd(); | |
1da177e4 LT |
835 | } |
836 | EXPORT_SYMBOL(release_console_sem); | |
837 | ||
ddad86c2 MW |
838 | /** |
839 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
840 | * |
841 | * If the console code is currently allowed to sleep, and | |
842 | * if this CPU should yield the CPU to another task, do | |
843 | * so here. | |
844 | * | |
845 | * Must be called within acquire_console_sem(). | |
846 | */ | |
847 | void __sched console_conditional_schedule(void) | |
848 | { | |
849 | if (console_may_schedule) | |
850 | cond_resched(); | |
851 | } | |
852 | EXPORT_SYMBOL(console_conditional_schedule); | |
853 | ||
854 | void console_print(const char *s) | |
855 | { | |
856 | printk(KERN_EMERG "%s", s); | |
857 | } | |
858 | EXPORT_SYMBOL(console_print); | |
859 | ||
860 | void console_unblank(void) | |
861 | { | |
862 | struct console *c; | |
863 | ||
864 | /* | |
865 | * console_unblank can no longer be called in interrupt context unless | |
866 | * oops_in_progress is set to 1.. | |
867 | */ | |
868 | if (oops_in_progress) { | |
869 | if (down_trylock(&console_sem) != 0) | |
870 | return; | |
871 | } else | |
872 | acquire_console_sem(); | |
873 | ||
874 | console_locked = 1; | |
875 | console_may_schedule = 0; | |
876 | for (c = console_drivers; c != NULL; c = c->next) | |
877 | if ((c->flags & CON_ENABLED) && c->unblank) | |
878 | c->unblank(); | |
879 | release_console_sem(); | |
880 | } | |
1da177e4 LT |
881 | |
882 | /* | |
883 | * Return the console tty driver structure and its associated index | |
884 | */ | |
885 | struct tty_driver *console_device(int *index) | |
886 | { | |
887 | struct console *c; | |
888 | struct tty_driver *driver = NULL; | |
889 | ||
890 | acquire_console_sem(); | |
891 | for (c = console_drivers; c != NULL; c = c->next) { | |
892 | if (!c->device) | |
893 | continue; | |
894 | driver = c->device(c, index); | |
895 | if (driver) | |
896 | break; | |
897 | } | |
898 | release_console_sem(); | |
899 | return driver; | |
900 | } | |
901 | ||
902 | /* | |
903 | * Prevent further output on the passed console device so that (for example) | |
904 | * serial drivers can disable console output before suspending a port, and can | |
905 | * re-enable output afterwards. | |
906 | */ | |
907 | void console_stop(struct console *console) | |
908 | { | |
909 | acquire_console_sem(); | |
910 | console->flags &= ~CON_ENABLED; | |
911 | release_console_sem(); | |
912 | } | |
913 | EXPORT_SYMBOL(console_stop); | |
914 | ||
915 | void console_start(struct console *console) | |
916 | { | |
917 | acquire_console_sem(); | |
918 | console->flags |= CON_ENABLED; | |
919 | release_console_sem(); | |
920 | } | |
921 | EXPORT_SYMBOL(console_start); | |
922 | ||
923 | /* | |
924 | * The console driver calls this routine during kernel initialization | |
925 | * to register the console printing procedure with printk() and to | |
926 | * print any messages that were printed by the kernel before the | |
927 | * console driver was initialized. | |
928 | */ | |
40dc5651 | 929 | void register_console(struct console *console) |
1da177e4 | 930 | { |
40dc5651 | 931 | int i; |
1da177e4 | 932 | unsigned long flags; |
69331af7 | 933 | struct console *bootconsole = NULL; |
1da177e4 | 934 | |
69331af7 GH |
935 | if (console_drivers) { |
936 | if (console->flags & CON_BOOT) | |
937 | return; | |
938 | if (console_drivers->flags & CON_BOOT) | |
939 | bootconsole = console_drivers; | |
940 | } | |
941 | ||
942 | if (preferred_console < 0 || bootconsole || !console_drivers) | |
1da177e4 LT |
943 | preferred_console = selected_console; |
944 | ||
945 | /* | |
946 | * See if we want to use this console driver. If we | |
947 | * didn't select a console we take the first one | |
948 | * that registers here. | |
949 | */ | |
950 | if (preferred_console < 0) { | |
951 | if (console->index < 0) | |
952 | console->index = 0; | |
953 | if (console->setup == NULL || | |
954 | console->setup(console, NULL) == 0) { | |
955 | console->flags |= CON_ENABLED | CON_CONSDEV; | |
956 | preferred_console = 0; | |
957 | } | |
958 | } | |
959 | ||
960 | /* | |
961 | * See if this console matches one we selected on | |
962 | * the command line. | |
963 | */ | |
40dc5651 JJ |
964 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
965 | i++) { | |
1da177e4 LT |
966 | if (strcmp(console_cmdline[i].name, console->name) != 0) |
967 | continue; | |
968 | if (console->index >= 0 && | |
969 | console->index != console_cmdline[i].index) | |
970 | continue; | |
971 | if (console->index < 0) | |
972 | console->index = console_cmdline[i].index; | |
973 | if (console->setup && | |
974 | console->setup(console, console_cmdline[i].options) != 0) | |
975 | break; | |
976 | console->flags |= CON_ENABLED; | |
977 | console->index = console_cmdline[i].index; | |
ab4af03a | 978 | if (i == selected_console) { |
1da177e4 | 979 | console->flags |= CON_CONSDEV; |
ab4af03a GE |
980 | preferred_console = selected_console; |
981 | } | |
1da177e4 LT |
982 | break; |
983 | } | |
984 | ||
985 | if (!(console->flags & CON_ENABLED)) | |
986 | return; | |
987 | ||
d37bf60d | 988 | if (bootconsole && (console->flags & CON_CONSDEV)) { |
69331af7 GH |
989 | printk(KERN_INFO "console handover: boot [%s%d] -> real [%s%d]\n", |
990 | bootconsole->name, bootconsole->index, | |
991 | console->name, console->index); | |
992 | unregister_console(bootconsole); | |
1da177e4 | 993 | console->flags &= ~CON_PRINTBUFFER; |
d37bf60d YL |
994 | } else { |
995 | printk(KERN_INFO "console [%s%d] enabled\n", | |
996 | console->name, console->index); | |
1da177e4 LT |
997 | } |
998 | ||
999 | /* | |
1000 | * Put this console in the list - keep the | |
1001 | * preferred driver at the head of the list. | |
1002 | */ | |
1003 | acquire_console_sem(); | |
1004 | if ((console->flags & CON_CONSDEV) || console_drivers == NULL) { | |
1005 | console->next = console_drivers; | |
1006 | console_drivers = console; | |
ab4af03a GE |
1007 | if (console->next) |
1008 | console->next->flags &= ~CON_CONSDEV; | |
1da177e4 LT |
1009 | } else { |
1010 | console->next = console_drivers->next; | |
1011 | console_drivers->next = console; | |
1012 | } | |
1013 | if (console->flags & CON_PRINTBUFFER) { | |
1014 | /* | |
1015 | * release_console_sem() will print out the buffered messages | |
1016 | * for us. | |
1017 | */ | |
1018 | spin_lock_irqsave(&logbuf_lock, flags); | |
1019 | con_start = log_start; | |
1020 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1021 | } | |
1022 | release_console_sem(); | |
1023 | } | |
1024 | EXPORT_SYMBOL(register_console); | |
1025 | ||
40dc5651 | 1026 | int unregister_console(struct console *console) |
1da177e4 | 1027 | { |
40dc5651 | 1028 | struct console *a, *b; |
1da177e4 LT |
1029 | int res = 1; |
1030 | ||
1031 | acquire_console_sem(); | |
1032 | if (console_drivers == console) { | |
1033 | console_drivers=console->next; | |
1034 | res = 0; | |
e9b15b54 | 1035 | } else if (console_drivers) { |
1da177e4 LT |
1036 | for (a=console_drivers->next, b=console_drivers ; |
1037 | a; b=a, a=b->next) { | |
1038 | if (a == console) { | |
1039 | b->next = a->next; | |
1040 | res = 0; | |
1041 | break; | |
40dc5651 | 1042 | } |
1da177e4 LT |
1043 | } |
1044 | } | |
40dc5651 | 1045 | |
69331af7 | 1046 | /* |
ab4af03a GE |
1047 | * If this isn't the last console and it has CON_CONSDEV set, we |
1048 | * need to set it on the next preferred console. | |
1da177e4 | 1049 | */ |
69331af7 | 1050 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1051 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 LT |
1052 | |
1053 | release_console_sem(); | |
1054 | return res; | |
1055 | } | |
1056 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1057 | |
1da177e4 LT |
1058 | /** |
1059 | * tty_write_message - write a message to a certain tty, not just the console. | |
ddad86c2 MW |
1060 | * @tty: the destination tty_struct |
1061 | * @msg: the message to write | |
1da177e4 LT |
1062 | * |
1063 | * This is used for messages that need to be redirected to a specific tty. | |
1064 | * We don't put it into the syslog queue right now maybe in the future if | |
1065 | * really needed. | |
1066 | */ | |
1067 | void tty_write_message(struct tty_struct *tty, char *msg) | |
1068 | { | |
1069 | if (tty && tty->driver->write) | |
1070 | tty->driver->write(tty, msg, strlen(msg)); | |
1071 | return; | |
1072 | } | |
1073 | ||
1074 | /* | |
1075 | * printk rate limiting, lifted from the networking subsystem. | |
1076 | * | |
1077 | * This enforces a rate limit: not more than one kernel message | |
1078 | * every printk_ratelimit_jiffies to make a denial-of-service | |
1079 | * attack impossible. | |
1080 | */ | |
1081 | int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst) | |
1082 | { | |
1083 | static DEFINE_SPINLOCK(ratelimit_lock); | |
40dc5651 | 1084 | static unsigned long toks = 10 * 5 * HZ; |
1da177e4 LT |
1085 | static unsigned long last_msg; |
1086 | static int missed; | |
1087 | unsigned long flags; | |
1088 | unsigned long now = jiffies; | |
1089 | ||
1090 | spin_lock_irqsave(&ratelimit_lock, flags); | |
1091 | toks += now - last_msg; | |
1092 | last_msg = now; | |
1093 | if (toks > (ratelimit_burst * ratelimit_jiffies)) | |
1094 | toks = ratelimit_burst * ratelimit_jiffies; | |
1095 | if (toks >= ratelimit_jiffies) { | |
1096 | int lost = missed; | |
40dc5651 | 1097 | |
1da177e4 LT |
1098 | missed = 0; |
1099 | toks -= ratelimit_jiffies; | |
1100 | spin_unlock_irqrestore(&ratelimit_lock, flags); | |
1101 | if (lost) | |
1102 | printk(KERN_WARNING "printk: %d messages suppressed.\n", lost); | |
1103 | return 1; | |
1104 | } | |
1105 | missed++; | |
1106 | spin_unlock_irqrestore(&ratelimit_lock, flags); | |
1107 | return 0; | |
1108 | } | |
1109 | EXPORT_SYMBOL(__printk_ratelimit); | |
1110 | ||
1111 | /* minimum time in jiffies between messages */ | |
40dc5651 | 1112 | int printk_ratelimit_jiffies = 5 * HZ; |
1da177e4 LT |
1113 | |
1114 | /* number of messages we send before ratelimiting */ | |
1115 | int printk_ratelimit_burst = 10; | |
1116 | ||
1117 | int printk_ratelimit(void) | |
1118 | { | |
1119 | return __printk_ratelimit(printk_ratelimit_jiffies, | |
1120 | printk_ratelimit_burst); | |
1121 | } | |
1122 | EXPORT_SYMBOL(printk_ratelimit); | |
f46c4833 AM |
1123 | |
1124 | /** | |
1125 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1126 | * @caller_jiffies: pointer to caller's state | |
1127 | * @interval_msecs: minimum interval between prints | |
1128 | * | |
1129 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1130 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1131 | * returned true. | |
1132 | */ | |
1133 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1134 | unsigned int interval_msecs) | |
1135 | { | |
1136 | if (*caller_jiffies == 0 || time_after(jiffies, *caller_jiffies)) { | |
1137 | *caller_jiffies = jiffies + msecs_to_jiffies(interval_msecs); | |
1138 | return true; | |
1139 | } | |
1140 | return false; | |
1141 | } | |
1142 | EXPORT_SYMBOL(printk_timed_ratelimit); |