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Commit | Line | Data |
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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> | |
3b9c0410 | 27 | #include <linux/moduleparam.h> |
1da177e4 | 28 | #include <linux/interrupt.h> /* For in_interrupt() */ |
1da177e4 LT |
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 | ||
c0fc84d2 | 55 | EXPORT_UNUSED_SYMBOL(console_printk); /* June 2006 */ |
1da177e4 LT |
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); | |
557240b4 | 70 | static DECLARE_MUTEX(secondary_console_sem); |
1da177e4 LT |
71 | struct console *console_drivers; |
72 | /* | |
73 | * This is used for debugging the mess that is the VT code by | |
74 | * keeping track if we have the console semaphore held. It's | |
75 | * definitely not the perfect debug tool (we don't know if _WE_ | |
76 | * hold it are racing, but it helps tracking those weird code | |
77 | * path in the console code where we end up in places I want | |
78 | * locked without the console sempahore held | |
79 | */ | |
557240b4 | 80 | static int console_locked, console_suspended; |
1da177e4 LT |
81 | |
82 | /* | |
83 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
84 | * It is also used in interesting ways to provide interlocking in | |
85 | * release_console_sem(). | |
86 | */ | |
87 | static DEFINE_SPINLOCK(logbuf_lock); | |
88 | ||
1da177e4 LT |
89 | #define LOG_BUF_MASK (log_buf_len-1) |
90 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) | |
91 | ||
92 | /* | |
93 | * The indices into log_buf are not constrained to log_buf_len - they | |
94 | * must be masked before subscripting | |
95 | */ | |
96 | static unsigned long log_start; /* Index into log_buf: next char to be read by syslog() */ | |
97 | static unsigned long con_start; /* Index into log_buf: next char to be sent to consoles */ | |
98 | static unsigned long log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
99 | |
100 | /* | |
101 | * Array of consoles built from command line options (console=) | |
102 | */ | |
103 | struct console_cmdline | |
104 | { | |
105 | char name[8]; /* Name of the driver */ | |
106 | int index; /* Minor dev. to use */ | |
107 | char *options; /* Options for the driver */ | |
108 | }; | |
109 | ||
110 | #define MAX_CMDLINECONSOLES 8 | |
111 | ||
112 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
113 | static int selected_console = -1; | |
114 | static int preferred_console = -1; | |
115 | ||
116 | /* Flag: console code may call schedule() */ | |
117 | static int console_may_schedule; | |
118 | ||
d59745ce MM |
119 | #ifdef CONFIG_PRINTK |
120 | ||
121 | static char __log_buf[__LOG_BUF_LEN]; | |
122 | static char *log_buf = __log_buf; | |
123 | static int log_buf_len = __LOG_BUF_LEN; | |
124 | static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */ | |
125 | ||
1da177e4 LT |
126 | static int __init log_buf_len_setup(char *str) |
127 | { | |
128 | unsigned long size = memparse(str, &str); | |
129 | unsigned long flags; | |
130 | ||
131 | if (size) | |
132 | size = roundup_pow_of_two(size); | |
133 | if (size > log_buf_len) { | |
134 | unsigned long start, dest_idx, offset; | |
40dc5651 | 135 | char *new_log_buf; |
1da177e4 LT |
136 | |
137 | new_log_buf = alloc_bootmem(size); | |
138 | if (!new_log_buf) { | |
40dc5651 | 139 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
140 | goto out; |
141 | } | |
142 | ||
143 | spin_lock_irqsave(&logbuf_lock, flags); | |
144 | log_buf_len = size; | |
145 | log_buf = new_log_buf; | |
146 | ||
147 | offset = start = min(con_start, log_start); | |
148 | dest_idx = 0; | |
149 | while (start != log_end) { | |
150 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
151 | start++; | |
152 | dest_idx++; | |
153 | } | |
154 | log_start -= offset; | |
155 | con_start -= offset; | |
156 | log_end -= offset; | |
157 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
158 | ||
40dc5651 | 159 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
160 | } |
161 | out: | |
1da177e4 LT |
162 | return 1; |
163 | } | |
164 | ||
165 | __setup("log_buf_len=", log_buf_len_setup); | |
166 | ||
167 | /* | |
168 | * Commands to do_syslog: | |
169 | * | |
170 | * 0 -- Close the log. Currently a NOP. | |
171 | * 1 -- Open the log. Currently a NOP. | |
172 | * 2 -- Read from the log. | |
173 | * 3 -- Read all messages remaining in the ring buffer. | |
174 | * 4 -- Read and clear all messages remaining in the ring buffer | |
175 | * 5 -- Clear ring buffer. | |
176 | * 6 -- Disable printk's to console | |
177 | * 7 -- Enable printk's to console | |
178 | * 8 -- Set level of messages printed to console | |
179 | * 9 -- Return number of unread characters in the log buffer | |
180 | * 10 -- Return size of the log buffer | |
181 | */ | |
40dc5651 | 182 | int do_syslog(int type, char __user *buf, int len) |
1da177e4 LT |
183 | { |
184 | unsigned long i, j, limit, count; | |
185 | int do_clear = 0; | |
186 | char c; | |
187 | int error = 0; | |
188 | ||
189 | error = security_syslog(type); | |
190 | if (error) | |
191 | return error; | |
192 | ||
193 | switch (type) { | |
194 | case 0: /* Close log */ | |
195 | break; | |
196 | case 1: /* Open log */ | |
197 | break; | |
198 | case 2: /* Read from log */ | |
199 | error = -EINVAL; | |
200 | if (!buf || len < 0) | |
201 | goto out; | |
202 | error = 0; | |
203 | if (!len) | |
204 | goto out; | |
205 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
206 | error = -EFAULT; | |
207 | goto out; | |
208 | } | |
40dc5651 JJ |
209 | error = wait_event_interruptible(log_wait, |
210 | (log_start - log_end)); | |
1da177e4 LT |
211 | if (error) |
212 | goto out; | |
213 | i = 0; | |
214 | spin_lock_irq(&logbuf_lock); | |
215 | while (!error && (log_start != log_end) && i < len) { | |
216 | c = LOG_BUF(log_start); | |
217 | log_start++; | |
218 | spin_unlock_irq(&logbuf_lock); | |
219 | error = __put_user(c,buf); | |
220 | buf++; | |
221 | i++; | |
222 | cond_resched(); | |
223 | spin_lock_irq(&logbuf_lock); | |
224 | } | |
225 | spin_unlock_irq(&logbuf_lock); | |
226 | if (!error) | |
227 | error = i; | |
228 | break; | |
229 | case 4: /* Read/clear last kernel messages */ | |
40dc5651 | 230 | do_clear = 1; |
1da177e4 LT |
231 | /* FALL THRU */ |
232 | case 3: /* Read last kernel messages */ | |
233 | error = -EINVAL; | |
234 | if (!buf || len < 0) | |
235 | goto out; | |
236 | error = 0; | |
237 | if (!len) | |
238 | goto out; | |
239 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
240 | error = -EFAULT; | |
241 | goto out; | |
242 | } | |
243 | count = len; | |
244 | if (count > log_buf_len) | |
245 | count = log_buf_len; | |
246 | spin_lock_irq(&logbuf_lock); | |
247 | if (count > logged_chars) | |
248 | count = logged_chars; | |
249 | if (do_clear) | |
250 | logged_chars = 0; | |
251 | limit = log_end; | |
252 | /* | |
253 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 254 | * printk() could overwrite the messages |
1da177e4 LT |
255 | * we try to copy to user space. Therefore |
256 | * the messages are copied in reverse. <manfreds> | |
257 | */ | |
40dc5651 | 258 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
259 | j = limit-1-i; |
260 | if (j + log_buf_len < log_end) | |
261 | break; | |
262 | c = LOG_BUF(j); | |
263 | spin_unlock_irq(&logbuf_lock); | |
264 | error = __put_user(c,&buf[count-1-i]); | |
265 | cond_resched(); | |
266 | spin_lock_irq(&logbuf_lock); | |
267 | } | |
268 | spin_unlock_irq(&logbuf_lock); | |
269 | if (error) | |
270 | break; | |
271 | error = i; | |
40dc5651 | 272 | if (i != count) { |
1da177e4 LT |
273 | int offset = count-error; |
274 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 275 | for (i = 0; i < error; i++) { |
1da177e4 LT |
276 | if (__get_user(c,&buf[i+offset]) || |
277 | __put_user(c,&buf[i])) { | |
278 | error = -EFAULT; | |
279 | break; | |
280 | } | |
281 | cond_resched(); | |
282 | } | |
283 | } | |
284 | break; | |
285 | case 5: /* Clear ring buffer */ | |
286 | logged_chars = 0; | |
287 | break; | |
288 | case 6: /* Disable logging to console */ | |
289 | console_loglevel = minimum_console_loglevel; | |
290 | break; | |
291 | case 7: /* Enable logging to console */ | |
292 | console_loglevel = default_console_loglevel; | |
293 | break; | |
294 | case 8: /* Set level of messages printed to console */ | |
295 | error = -EINVAL; | |
296 | if (len < 1 || len > 8) | |
297 | goto out; | |
298 | if (len < minimum_console_loglevel) | |
299 | len = minimum_console_loglevel; | |
300 | console_loglevel = len; | |
301 | error = 0; | |
302 | break; | |
303 | case 9: /* Number of chars in the log buffer */ | |
304 | error = log_end - log_start; | |
305 | break; | |
306 | case 10: /* Size of the log buffer */ | |
307 | error = log_buf_len; | |
308 | break; | |
309 | default: | |
310 | error = -EINVAL; | |
311 | break; | |
312 | } | |
313 | out: | |
314 | return error; | |
315 | } | |
316 | ||
40dc5651 | 317 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
1da177e4 LT |
318 | { |
319 | return do_syslog(type, buf, len); | |
320 | } | |
321 | ||
322 | /* | |
323 | * Call the console drivers on a range of log_buf | |
324 | */ | |
325 | static void __call_console_drivers(unsigned long start, unsigned long end) | |
326 | { | |
327 | struct console *con; | |
328 | ||
329 | for (con = console_drivers; con; con = con->next) { | |
76a8ad29 ME |
330 | if ((con->flags & CON_ENABLED) && con->write && |
331 | (cpu_online(smp_processor_id()) || | |
332 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
333 | con->write(con, &LOG_BUF(start), end - start); |
334 | } | |
335 | } | |
336 | ||
337 | /* | |
338 | * Write out chars from start to end - 1 inclusive | |
339 | */ | |
340 | static void _call_console_drivers(unsigned long start, | |
341 | unsigned long end, int msg_log_level) | |
342 | { | |
343 | if (msg_log_level < console_loglevel && | |
344 | console_drivers && start != end) { | |
345 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
346 | /* wrapped write */ | |
347 | __call_console_drivers(start & LOG_BUF_MASK, | |
348 | log_buf_len); | |
349 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
350 | } else { | |
351 | __call_console_drivers(start, end); | |
352 | } | |
353 | } | |
354 | } | |
355 | ||
356 | /* | |
357 | * Call the console drivers, asking them to write out | |
358 | * log_buf[start] to log_buf[end - 1]. | |
359 | * The console_sem must be held. | |
360 | */ | |
361 | static void call_console_drivers(unsigned long start, unsigned long end) | |
362 | { | |
363 | unsigned long cur_index, start_print; | |
364 | static int msg_level = -1; | |
365 | ||
8abd8e29 | 366 | BUG_ON(((long)(start - end)) > 0); |
1da177e4 LT |
367 | |
368 | cur_index = start; | |
369 | start_print = start; | |
370 | while (cur_index != end) { | |
40dc5651 JJ |
371 | if (msg_level < 0 && ((end - cur_index) > 2) && |
372 | LOG_BUF(cur_index + 0) == '<' && | |
373 | LOG_BUF(cur_index + 1) >= '0' && | |
374 | LOG_BUF(cur_index + 1) <= '7' && | |
375 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
376 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
377 | cur_index += 3; | |
378 | start_print = cur_index; | |
379 | } | |
380 | while (cur_index != end) { | |
381 | char c = LOG_BUF(cur_index); | |
1da177e4 | 382 | |
40dc5651 | 383 | cur_index++; |
1da177e4 LT |
384 | if (c == '\n') { |
385 | if (msg_level < 0) { | |
386 | /* | |
387 | * printk() has already given us loglevel tags in | |
388 | * the buffer. This code is here in case the | |
389 | * log buffer has wrapped right round and scribbled | |
390 | * on those tags | |
391 | */ | |
392 | msg_level = default_message_loglevel; | |
393 | } | |
394 | _call_console_drivers(start_print, cur_index, msg_level); | |
395 | msg_level = -1; | |
396 | start_print = cur_index; | |
397 | break; | |
398 | } | |
399 | } | |
400 | } | |
401 | _call_console_drivers(start_print, end, msg_level); | |
402 | } | |
403 | ||
404 | static void emit_log_char(char c) | |
405 | { | |
406 | LOG_BUF(log_end) = c; | |
407 | log_end++; | |
408 | if (log_end - log_start > log_buf_len) | |
409 | log_start = log_end - log_buf_len; | |
410 | if (log_end - con_start > log_buf_len) | |
411 | con_start = log_end - log_buf_len; | |
412 | if (logged_chars < log_buf_len) | |
413 | logged_chars++; | |
414 | } | |
415 | ||
416 | /* | |
417 | * Zap console related locks when oopsing. Only zap at most once | |
418 | * every 10 seconds, to leave time for slow consoles to print a | |
419 | * full oops. | |
420 | */ | |
421 | static void zap_locks(void) | |
422 | { | |
423 | static unsigned long oops_timestamp; | |
424 | ||
425 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 426 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
427 | return; |
428 | ||
429 | oops_timestamp = jiffies; | |
430 | ||
431 | /* If a crash is occurring, make sure we can't deadlock */ | |
432 | spin_lock_init(&logbuf_lock); | |
433 | /* And make sure that we print immediately */ | |
434 | init_MUTEX(&console_sem); | |
435 | } | |
436 | ||
437 | #if defined(CONFIG_PRINTK_TIME) | |
438 | static int printk_time = 1; | |
439 | #else | |
440 | static int printk_time = 0; | |
441 | #endif | |
3b9c0410 | 442 | module_param(printk_time, int, S_IRUGO | S_IWUSR); |
1da177e4 LT |
443 | |
444 | static int __init printk_time_setup(char *str) | |
445 | { | |
446 | if (*str) | |
447 | return 0; | |
448 | printk_time = 1; | |
449 | return 1; | |
450 | } | |
451 | ||
452 | __setup("time", printk_time_setup); | |
453 | ||
31f6d9d6 AM |
454 | __attribute__((weak)) unsigned long long printk_clock(void) |
455 | { | |
456 | return sched_clock(); | |
457 | } | |
458 | ||
76a8ad29 ME |
459 | /* Check if we have any console registered that can be called early in boot. */ |
460 | static int have_callable_console(void) | |
461 | { | |
462 | struct console *con; | |
463 | ||
464 | for (con = console_drivers; con; con = con->next) | |
465 | if (con->flags & CON_ANYTIME) | |
466 | return 1; | |
467 | ||
468 | return 0; | |
469 | } | |
470 | ||
ddad86c2 MW |
471 | /** |
472 | * printk - print a kernel message | |
473 | * @fmt: format string | |
474 | * | |
1da177e4 | 475 | * This is printk. It can be called from any context. We want it to work. |
40dc5651 | 476 | * |
1da177e4 LT |
477 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
478 | * call the console drivers. If we fail to get the semaphore we place the output | |
479 | * into the log buffer and return. The current holder of the console_sem will | |
480 | * notice the new output in release_console_sem() and will send it to the | |
481 | * consoles before releasing the semaphore. | |
482 | * | |
483 | * One effect of this deferred printing is that code which calls printk() and | |
484 | * then changes console_loglevel may break. This is because console_loglevel | |
485 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
486 | * |
487 | * See also: | |
488 | * printf(3) | |
1da177e4 | 489 | */ |
d59745ce | 490 | |
1da177e4 LT |
491 | asmlinkage int printk(const char *fmt, ...) |
492 | { | |
493 | va_list args; | |
494 | int r; | |
495 | ||
496 | va_start(args, fmt); | |
497 | r = vprintk(fmt, args); | |
498 | va_end(args); | |
499 | ||
500 | return r; | |
501 | } | |
502 | ||
fe21773d DH |
503 | /* cpu currently holding logbuf_lock */ |
504 | static volatile unsigned int printk_cpu = UINT_MAX; | |
505 | ||
1da177e4 LT |
506 | asmlinkage int vprintk(const char *fmt, va_list args) |
507 | { | |
508 | unsigned long flags; | |
509 | int printed_len; | |
510 | char *p; | |
511 | static char printk_buf[1024]; | |
512 | static int log_level_unknown = 1; | |
513 | ||
fe21773d DH |
514 | preempt_disable(); |
515 | if (unlikely(oops_in_progress) && printk_cpu == smp_processor_id()) | |
516 | /* If a crash is occurring during printk() on this CPU, | |
517 | * make sure we can't deadlock */ | |
1da177e4 LT |
518 | zap_locks(); |
519 | ||
520 | /* This stops the holder of console_sem just where we want him */ | |
a0f1ccfd IM |
521 | local_irq_save(flags); |
522 | lockdep_off(); | |
523 | spin_lock(&logbuf_lock); | |
fe21773d | 524 | printk_cpu = smp_processor_id(); |
1da177e4 LT |
525 | |
526 | /* Emit the output into the temporary buffer */ | |
527 | printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args); | |
528 | ||
529 | /* | |
530 | * Copy the output into log_buf. If the caller didn't provide | |
531 | * appropriate log level tags, we insert them here | |
532 | */ | |
533 | for (p = printk_buf; *p; p++) { | |
534 | if (log_level_unknown) { | |
535 | /* log_level_unknown signals the start of a new line */ | |
536 | if (printk_time) { | |
537 | int loglev_char; | |
538 | char tbuf[50], *tp; | |
539 | unsigned tlen; | |
540 | unsigned long long t; | |
541 | unsigned long nanosec_rem; | |
542 | ||
543 | /* | |
544 | * force the log level token to be | |
545 | * before the time output. | |
546 | */ | |
547 | if (p[0] == '<' && p[1] >='0' && | |
548 | p[1] <= '7' && p[2] == '>') { | |
549 | loglev_char = p[1]; | |
550 | p += 3; | |
025510cd | 551 | printed_len -= 3; |
1da177e4 LT |
552 | } else { |
553 | loglev_char = default_message_loglevel | |
554 | + '0'; | |
555 | } | |
31f6d9d6 | 556 | t = printk_clock(); |
1da177e4 LT |
557 | nanosec_rem = do_div(t, 1000000000); |
558 | tlen = sprintf(tbuf, | |
559 | "<%c>[%5lu.%06lu] ", | |
560 | loglev_char, | |
561 | (unsigned long)t, | |
562 | nanosec_rem/1000); | |
563 | ||
564 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
565 | emit_log_char(*tp); | |
025510cd | 566 | printed_len += tlen; |
1da177e4 LT |
567 | } else { |
568 | if (p[0] != '<' || p[1] < '0' || | |
569 | p[1] > '7' || p[2] != '>') { | |
570 | emit_log_char('<'); | |
571 | emit_log_char(default_message_loglevel | |
572 | + '0'); | |
573 | emit_log_char('>'); | |
025510cd | 574 | printed_len += 3; |
1da177e4 | 575 | } |
1da177e4 LT |
576 | } |
577 | log_level_unknown = 0; | |
578 | if (!*p) | |
579 | break; | |
580 | } | |
581 | emit_log_char(*p); | |
582 | if (*p == '\n') | |
583 | log_level_unknown = 1; | |
584 | } | |
585 | ||
76a8ad29 | 586 | if (!down_trylock(&console_sem)) { |
1da177e4 | 587 | /* |
76a8ad29 ME |
588 | * We own the drivers. We can drop the spinlock and |
589 | * let release_console_sem() print the text, maybe ... | |
1da177e4 | 590 | */ |
76a8ad29 | 591 | console_locked = 1; |
fe21773d | 592 | printk_cpu = UINT_MAX; |
a0f1ccfd | 593 | spin_unlock(&logbuf_lock); |
76a8ad29 | 594 | |
1da177e4 | 595 | /* |
76a8ad29 ME |
596 | * Console drivers may assume that per-cpu resources have |
597 | * been allocated. So unless they're explicitly marked as | |
598 | * being able to cope (CON_ANYTIME) don't call them until | |
599 | * this CPU is officially up. | |
1da177e4 | 600 | */ |
76a8ad29 ME |
601 | if (cpu_online(smp_processor_id()) || have_callable_console()) { |
602 | console_may_schedule = 0; | |
603 | release_console_sem(); | |
604 | } else { | |
605 | /* Release by hand to avoid flushing the buffer. */ | |
606 | console_locked = 0; | |
607 | up(&console_sem); | |
608 | } | |
a0f1ccfd IM |
609 | lockdep_on(); |
610 | local_irq_restore(flags); | |
1da177e4 LT |
611 | } else { |
612 | /* | |
613 | * Someone else owns the drivers. We drop the spinlock, which | |
614 | * allows the semaphore holder to proceed and to call the | |
615 | * console drivers with the output which we just produced. | |
616 | */ | |
fe21773d | 617 | printk_cpu = UINT_MAX; |
a0f1ccfd IM |
618 | spin_unlock(&logbuf_lock); |
619 | lockdep_on(); | |
620 | local_irq_restore(flags); | |
1da177e4 | 621 | } |
76a8ad29 | 622 | |
fe21773d | 623 | preempt_enable(); |
1da177e4 LT |
624 | return printed_len; |
625 | } | |
626 | EXPORT_SYMBOL(printk); | |
627 | EXPORT_SYMBOL(vprintk); | |
628 | ||
d59745ce MM |
629 | #else |
630 | ||
40dc5651 | 631 | asmlinkage long sys_syslog(int type, char __user *buf, int len) |
d59745ce MM |
632 | { |
633 | return 0; | |
634 | } | |
635 | ||
40dc5651 JJ |
636 | int do_syslog(int type, char __user *buf, int len) |
637 | { | |
638 | return 0; | |
639 | } | |
640 | ||
641 | static void call_console_drivers(unsigned long start, unsigned long end) | |
642 | { | |
643 | } | |
d59745ce MM |
644 | |
645 | #endif | |
646 | ||
2ea1c539 JB |
647 | /* |
648 | * Set up a list of consoles. Called from init/main.c | |
649 | */ | |
650 | static int __init console_setup(char *str) | |
651 | { | |
652 | char name[sizeof(console_cmdline[0].name)]; | |
653 | char *s, *options; | |
654 | int idx; | |
655 | ||
656 | /* | |
657 | * Decode str into name, index, options. | |
658 | */ | |
659 | if (str[0] >= '0' && str[0] <= '9') { | |
660 | strcpy(name, "ttyS"); | |
661 | strncpy(name + 4, str, sizeof(name) - 5); | |
662 | } else { | |
663 | strncpy(name, str, sizeof(name) - 1); | |
664 | } | |
665 | name[sizeof(name) - 1] = 0; | |
666 | if ((options = strchr(str, ',')) != NULL) | |
667 | *(options++) = 0; | |
668 | #ifdef __sparc__ | |
669 | if (!strcmp(str, "ttya")) | |
670 | strcpy(name, "ttyS0"); | |
671 | if (!strcmp(str, "ttyb")) | |
672 | strcpy(name, "ttyS1"); | |
673 | #endif | |
674 | for (s = name; *s; s++) | |
675 | if ((*s >= '0' && *s <= '9') || *s == ',') | |
676 | break; | |
677 | idx = simple_strtoul(s, NULL, 10); | |
678 | *s = 0; | |
679 | ||
680 | add_preferred_console(name, idx, options); | |
681 | return 1; | |
682 | } | |
683 | __setup("console=", console_setup); | |
684 | ||
3c0547ba MM |
685 | /** |
686 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
687 | * @name: device name |
688 | * @idx: device index | |
689 | * @options: options for this console | |
3c0547ba MM |
690 | * |
691 | * The last preferred console added will be used for kernel messages | |
692 | * and stdin/out/err for init. Normally this is used by console_setup | |
693 | * above to handle user-supplied console arguments; however it can also | |
694 | * be used by arch-specific code either to override the user or more | |
695 | * commonly to provide a default console (ie from PROM variables) when | |
696 | * the user has not supplied one. | |
697 | */ | |
698 | int __init add_preferred_console(char *name, int idx, char *options) | |
699 | { | |
700 | struct console_cmdline *c; | |
701 | int i; | |
702 | ||
703 | /* | |
704 | * See if this tty is not yet registered, and | |
705 | * if we have a slot free. | |
706 | */ | |
707 | for(i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
708 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
709 | console_cmdline[i].index == idx) { | |
710 | selected_console = i; | |
711 | return 0; | |
712 | } | |
713 | if (i == MAX_CMDLINECONSOLES) | |
714 | return -E2BIG; | |
715 | selected_console = i; | |
716 | c = &console_cmdline[i]; | |
717 | memcpy(c->name, name, sizeof(c->name)); | |
718 | c->name[sizeof(c->name) - 1] = 0; | |
719 | c->options = options; | |
720 | c->index = idx; | |
721 | return 0; | |
722 | } | |
723 | ||
557240b4 LT |
724 | /** |
725 | * suspend_console - suspend the console subsystem | |
726 | * | |
727 | * This disables printk() while we go into suspend states | |
728 | */ | |
729 | void suspend_console(void) | |
730 | { | |
731 | acquire_console_sem(); | |
732 | console_suspended = 1; | |
733 | } | |
734 | ||
735 | void resume_console(void) | |
736 | { | |
737 | console_suspended = 0; | |
738 | release_console_sem(); | |
739 | } | |
740 | ||
1da177e4 LT |
741 | /** |
742 | * acquire_console_sem - lock the console system for exclusive use. | |
743 | * | |
744 | * Acquires a semaphore which guarantees that the caller has | |
745 | * exclusive access to the console system and the console_drivers list. | |
746 | * | |
747 | * Can sleep, returns nothing. | |
748 | */ | |
749 | void acquire_console_sem(void) | |
750 | { | |
8abd8e29 | 751 | BUG_ON(in_interrupt()); |
557240b4 LT |
752 | if (console_suspended) { |
753 | down(&secondary_console_sem); | |
754 | return; | |
755 | } | |
1da177e4 LT |
756 | down(&console_sem); |
757 | console_locked = 1; | |
758 | console_may_schedule = 1; | |
759 | } | |
760 | EXPORT_SYMBOL(acquire_console_sem); | |
761 | ||
762 | int try_acquire_console_sem(void) | |
763 | { | |
764 | if (down_trylock(&console_sem)) | |
765 | return -1; | |
766 | console_locked = 1; | |
767 | console_may_schedule = 0; | |
768 | return 0; | |
769 | } | |
770 | EXPORT_SYMBOL(try_acquire_console_sem); | |
771 | ||
772 | int is_console_locked(void) | |
773 | { | |
774 | return console_locked; | |
775 | } | |
c0fc84d2 | 776 | EXPORT_UNUSED_SYMBOL(is_console_locked); /* June 2006 */ |
1da177e4 LT |
777 | |
778 | /** | |
779 | * release_console_sem - unlock the console system | |
780 | * | |
781 | * Releases the semaphore which the caller holds on the console system | |
782 | * and the console driver list. | |
783 | * | |
784 | * While the semaphore was held, console output may have been buffered | |
785 | * by printk(). If this is the case, release_console_sem() emits | |
786 | * the output prior to releasing the semaphore. | |
787 | * | |
788 | * If there is output waiting for klogd, we wake it up. | |
789 | * | |
790 | * release_console_sem() may be called from any context. | |
791 | */ | |
792 | void release_console_sem(void) | |
793 | { | |
794 | unsigned long flags; | |
795 | unsigned long _con_start, _log_end; | |
796 | unsigned long wake_klogd = 0; | |
797 | ||
557240b4 LT |
798 | if (console_suspended) { |
799 | up(&secondary_console_sem); | |
800 | return; | |
801 | } | |
78944e54 AD |
802 | |
803 | console_may_schedule = 0; | |
804 | ||
1da177e4 LT |
805 | for ( ; ; ) { |
806 | spin_lock_irqsave(&logbuf_lock, flags); | |
807 | wake_klogd |= log_start - log_end; | |
808 | if (con_start == log_end) | |
809 | break; /* Nothing to print */ | |
810 | _con_start = con_start; | |
811 | _log_end = log_end; | |
812 | con_start = log_end; /* Flush */ | |
813 | spin_unlock(&logbuf_lock); | |
814 | call_console_drivers(_con_start, _log_end); | |
815 | local_irq_restore(flags); | |
816 | } | |
817 | console_locked = 0; | |
1da177e4 LT |
818 | up(&console_sem); |
819 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
a0f1ccfd IM |
820 | if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait)) { |
821 | /* | |
822 | * If we printk from within the lock dependency code, | |
823 | * from within the scheduler code, then do not lock | |
824 | * up due to self-recursion: | |
825 | */ | |
826 | if (!lockdep_internal()) | |
827 | wake_up_interruptible(&log_wait); | |
828 | } | |
1da177e4 LT |
829 | } |
830 | EXPORT_SYMBOL(release_console_sem); | |
831 | ||
ddad86c2 MW |
832 | /** |
833 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
834 | * |
835 | * If the console code is currently allowed to sleep, and | |
836 | * if this CPU should yield the CPU to another task, do | |
837 | * so here. | |
838 | * | |
839 | * Must be called within acquire_console_sem(). | |
840 | */ | |
841 | void __sched console_conditional_schedule(void) | |
842 | { | |
843 | if (console_may_schedule) | |
844 | cond_resched(); | |
845 | } | |
846 | EXPORT_SYMBOL(console_conditional_schedule); | |
847 | ||
848 | void console_print(const char *s) | |
849 | { | |
850 | printk(KERN_EMERG "%s", s); | |
851 | } | |
852 | EXPORT_SYMBOL(console_print); | |
853 | ||
854 | void console_unblank(void) | |
855 | { | |
856 | struct console *c; | |
857 | ||
858 | /* | |
859 | * console_unblank can no longer be called in interrupt context unless | |
860 | * oops_in_progress is set to 1.. | |
861 | */ | |
862 | if (oops_in_progress) { | |
863 | if (down_trylock(&console_sem) != 0) | |
864 | return; | |
865 | } else | |
866 | acquire_console_sem(); | |
867 | ||
868 | console_locked = 1; | |
869 | console_may_schedule = 0; | |
870 | for (c = console_drivers; c != NULL; c = c->next) | |
871 | if ((c->flags & CON_ENABLED) && c->unblank) | |
872 | c->unblank(); | |
873 | release_console_sem(); | |
874 | } | |
1da177e4 LT |
875 | |
876 | /* | |
877 | * Return the console tty driver structure and its associated index | |
878 | */ | |
879 | struct tty_driver *console_device(int *index) | |
880 | { | |
881 | struct console *c; | |
882 | struct tty_driver *driver = NULL; | |
883 | ||
884 | acquire_console_sem(); | |
885 | for (c = console_drivers; c != NULL; c = c->next) { | |
886 | if (!c->device) | |
887 | continue; | |
888 | driver = c->device(c, index); | |
889 | if (driver) | |
890 | break; | |
891 | } | |
892 | release_console_sem(); | |
893 | return driver; | |
894 | } | |
895 | ||
896 | /* | |
897 | * Prevent further output on the passed console device so that (for example) | |
898 | * serial drivers can disable console output before suspending a port, and can | |
899 | * re-enable output afterwards. | |
900 | */ | |
901 | void console_stop(struct console *console) | |
902 | { | |
903 | acquire_console_sem(); | |
904 | console->flags &= ~CON_ENABLED; | |
905 | release_console_sem(); | |
906 | } | |
907 | EXPORT_SYMBOL(console_stop); | |
908 | ||
909 | void console_start(struct console *console) | |
910 | { | |
911 | acquire_console_sem(); | |
912 | console->flags |= CON_ENABLED; | |
913 | release_console_sem(); | |
914 | } | |
915 | EXPORT_SYMBOL(console_start); | |
916 | ||
917 | /* | |
918 | * The console driver calls this routine during kernel initialization | |
919 | * to register the console printing procedure with printk() and to | |
920 | * print any messages that were printed by the kernel before the | |
921 | * console driver was initialized. | |
922 | */ | |
40dc5651 | 923 | void register_console(struct console *console) |
1da177e4 | 924 | { |
40dc5651 | 925 | int i; |
1da177e4 LT |
926 | unsigned long flags; |
927 | ||
928 | if (preferred_console < 0) | |
929 | preferred_console = selected_console; | |
930 | ||
931 | /* | |
932 | * See if we want to use this console driver. If we | |
933 | * didn't select a console we take the first one | |
934 | * that registers here. | |
935 | */ | |
936 | if (preferred_console < 0) { | |
937 | if (console->index < 0) | |
938 | console->index = 0; | |
939 | if (console->setup == NULL || | |
940 | console->setup(console, NULL) == 0) { | |
941 | console->flags |= CON_ENABLED | CON_CONSDEV; | |
942 | preferred_console = 0; | |
943 | } | |
944 | } | |
945 | ||
946 | /* | |
947 | * See if this console matches one we selected on | |
948 | * the command line. | |
949 | */ | |
40dc5651 JJ |
950 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
951 | i++) { | |
1da177e4 LT |
952 | if (strcmp(console_cmdline[i].name, console->name) != 0) |
953 | continue; | |
954 | if (console->index >= 0 && | |
955 | console->index != console_cmdline[i].index) | |
956 | continue; | |
957 | if (console->index < 0) | |
958 | console->index = console_cmdline[i].index; | |
959 | if (console->setup && | |
960 | console->setup(console, console_cmdline[i].options) != 0) | |
961 | break; | |
962 | console->flags |= CON_ENABLED; | |
963 | console->index = console_cmdline[i].index; | |
ab4af03a | 964 | if (i == selected_console) { |
1da177e4 | 965 | console->flags |= CON_CONSDEV; |
ab4af03a GE |
966 | preferred_console = selected_console; |
967 | } | |
1da177e4 LT |
968 | break; |
969 | } | |
970 | ||
971 | if (!(console->flags & CON_ENABLED)) | |
972 | return; | |
973 | ||
974 | if (console_drivers && (console_drivers->flags & CON_BOOT)) { | |
975 | unregister_console(console_drivers); | |
976 | console->flags &= ~CON_PRINTBUFFER; | |
977 | } | |
978 | ||
979 | /* | |
980 | * Put this console in the list - keep the | |
981 | * preferred driver at the head of the list. | |
982 | */ | |
983 | acquire_console_sem(); | |
984 | if ((console->flags & CON_CONSDEV) || console_drivers == NULL) { | |
985 | console->next = console_drivers; | |
986 | console_drivers = console; | |
ab4af03a GE |
987 | if (console->next) |
988 | console->next->flags &= ~CON_CONSDEV; | |
1da177e4 LT |
989 | } else { |
990 | console->next = console_drivers->next; | |
991 | console_drivers->next = console; | |
992 | } | |
993 | if (console->flags & CON_PRINTBUFFER) { | |
994 | /* | |
995 | * release_console_sem() will print out the buffered messages | |
996 | * for us. | |
997 | */ | |
998 | spin_lock_irqsave(&logbuf_lock, flags); | |
999 | con_start = log_start; | |
1000 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1001 | } | |
1002 | release_console_sem(); | |
1003 | } | |
1004 | EXPORT_SYMBOL(register_console); | |
1005 | ||
40dc5651 | 1006 | int unregister_console(struct console *console) |
1da177e4 | 1007 | { |
40dc5651 | 1008 | struct console *a, *b; |
1da177e4 LT |
1009 | int res = 1; |
1010 | ||
1011 | acquire_console_sem(); | |
1012 | if (console_drivers == console) { | |
1013 | console_drivers=console->next; | |
1014 | res = 0; | |
e9b15b54 | 1015 | } else if (console_drivers) { |
1da177e4 LT |
1016 | for (a=console_drivers->next, b=console_drivers ; |
1017 | a; b=a, a=b->next) { | |
1018 | if (a == console) { | |
1019 | b->next = a->next; | |
1020 | res = 0; | |
1021 | break; | |
40dc5651 | 1022 | } |
1da177e4 LT |
1023 | } |
1024 | } | |
40dc5651 | 1025 | |
1da177e4 LT |
1026 | /* If last console is removed, we re-enable picking the first |
1027 | * one that gets registered. Without that, pmac early boot console | |
1028 | * would prevent fbcon from taking over. | |
ab4af03a GE |
1029 | * |
1030 | * If this isn't the last console and it has CON_CONSDEV set, we | |
1031 | * need to set it on the next preferred console. | |
1da177e4 LT |
1032 | */ |
1033 | if (console_drivers == NULL) | |
1034 | preferred_console = selected_console; | |
ab4af03a GE |
1035 | else if (console->flags & CON_CONSDEV) |
1036 | console_drivers->flags |= CON_CONSDEV; | |
1da177e4 LT |
1037 | |
1038 | release_console_sem(); | |
1039 | return res; | |
1040 | } | |
1041 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1042 | |
1da177e4 LT |
1043 | /** |
1044 | * tty_write_message - write a message to a certain tty, not just the console. | |
ddad86c2 MW |
1045 | * @tty: the destination tty_struct |
1046 | * @msg: the message to write | |
1da177e4 LT |
1047 | * |
1048 | * This is used for messages that need to be redirected to a specific tty. | |
1049 | * We don't put it into the syslog queue right now maybe in the future if | |
1050 | * really needed. | |
1051 | */ | |
1052 | void tty_write_message(struct tty_struct *tty, char *msg) | |
1053 | { | |
1054 | if (tty && tty->driver->write) | |
1055 | tty->driver->write(tty, msg, strlen(msg)); | |
1056 | return; | |
1057 | } | |
1058 | ||
1059 | /* | |
1060 | * printk rate limiting, lifted from the networking subsystem. | |
1061 | * | |
1062 | * This enforces a rate limit: not more than one kernel message | |
1063 | * every printk_ratelimit_jiffies to make a denial-of-service | |
1064 | * attack impossible. | |
1065 | */ | |
1066 | int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst) | |
1067 | { | |
1068 | static DEFINE_SPINLOCK(ratelimit_lock); | |
40dc5651 | 1069 | static unsigned long toks = 10 * 5 * HZ; |
1da177e4 LT |
1070 | static unsigned long last_msg; |
1071 | static int missed; | |
1072 | unsigned long flags; | |
1073 | unsigned long now = jiffies; | |
1074 | ||
1075 | spin_lock_irqsave(&ratelimit_lock, flags); | |
1076 | toks += now - last_msg; | |
1077 | last_msg = now; | |
1078 | if (toks > (ratelimit_burst * ratelimit_jiffies)) | |
1079 | toks = ratelimit_burst * ratelimit_jiffies; | |
1080 | if (toks >= ratelimit_jiffies) { | |
1081 | int lost = missed; | |
40dc5651 | 1082 | |
1da177e4 LT |
1083 | missed = 0; |
1084 | toks -= ratelimit_jiffies; | |
1085 | spin_unlock_irqrestore(&ratelimit_lock, flags); | |
1086 | if (lost) | |
1087 | printk(KERN_WARNING "printk: %d messages suppressed.\n", lost); | |
1088 | return 1; | |
1089 | } | |
1090 | missed++; | |
1091 | spin_unlock_irqrestore(&ratelimit_lock, flags); | |
1092 | return 0; | |
1093 | } | |
1094 | EXPORT_SYMBOL(__printk_ratelimit); | |
1095 | ||
1096 | /* minimum time in jiffies between messages */ | |
40dc5651 | 1097 | int printk_ratelimit_jiffies = 5 * HZ; |
1da177e4 LT |
1098 | |
1099 | /* number of messages we send before ratelimiting */ | |
1100 | int printk_ratelimit_burst = 10; | |
1101 | ||
1102 | int printk_ratelimit(void) | |
1103 | { | |
1104 | return __printk_ratelimit(printk_ratelimit_jiffies, | |
1105 | printk_ratelimit_burst); | |
1106 | } | |
1107 | EXPORT_SYMBOL(printk_ratelimit); |