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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. |
13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
14 | * manfred@colorfullife.com |
15 | * Rewrote bits to get rid of console_lock |
16 | * 01Mar01 Andrew Morton |
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/console.h> |
24 | #include <linux/init.h> |
25 | #include <linux/jiffies.h> |
26 | #include <linux/nmi.h> |
27 | #include <linux/module.h> |
28 | #include <linux/moduleparam.h> |
29 | #include <linux/interrupt.h> /* For in_interrupt() */ |
30 | #include <linux/delay.h> |
31 | #include <linux/smp.h> |
32 | #include <linux/security.h> |
33 | #include <linux/bootmem.h> |
34 | #include <linux/syscalls.h> |
35 | #include <linux/kexec.h> |
36 | #include <linux/ratelimit.h> |
37 | #include <linux/kmsg_dump.h> |
38 | #include <linux/syslog.h> |
39 | |
40 | #include <asm/uaccess.h> |
41 | |
42 | /* |
43 | * for_each_console() allows you to iterate on each console |
44 | */ |
45 | #define for_each_console(con) \ |
46 | for (con = console_drivers; con != NULL; con = con->next) |
47 | |
48 | /* |
49 | * Architectures can override it: |
50 | */ |
51 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
52 | { |
53 | } |
54 | |
55 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
56 | |
57 | /* printk's without a loglevel use this.. */ |
58 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ |
59 | |
60 | /* We show everything that is MORE important than this.. */ |
61 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ |
62 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ |
63 | |
64 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
65 | |
66 | int console_printk[4] = { |
67 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ |
68 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ |
69 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ |
70 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ |
71 | }; |
72 | |
73 | /* |
74 | * Low level drivers may need that to know if they can schedule in |
75 | * their unblank() callback or not. So let's export it. |
76 | */ |
77 | int oops_in_progress; |
78 | EXPORT_SYMBOL(oops_in_progress); |
79 | |
80 | /* |
81 | * console_sem protects the console_drivers list, and also |
82 | * provides serialisation for access to the entire console |
83 | * driver system. |
84 | */ |
85 | static DECLARE_MUTEX(console_sem); |
86 | struct console *console_drivers; |
87 | EXPORT_SYMBOL_GPL(console_drivers); |
88 | |
89 | /* |
90 | * This is used for debugging the mess that is the VT code by |
91 | * keeping track if we have the console semaphore held. It's |
92 | * definitely not the perfect debug tool (we don't know if _WE_ |
93 | * hold it are racing, but it helps tracking those weird code |
94 | * path in the console code where we end up in places I want |
95 | * locked without the console sempahore held |
96 | */ |
97 | static int console_locked, console_suspended; |
98 | |
99 | /* |
100 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars |
101 | * It is also used in interesting ways to provide interlocking in |
102 | * release_console_sem(). |
103 | */ |
104 | static DEFINE_SPINLOCK(logbuf_lock); |
105 | |
106 | #define LOG_BUF_MASK (log_buf_len-1) |
107 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
108 | |
109 | /* |
110 | * The indices into log_buf are not constrained to log_buf_len - they |
111 | * must be masked before subscripting |
112 | */ |
113 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
114 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ |
115 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ |
116 | |
117 | /* |
118 | * Array of consoles built from command line options (console=) |
119 | */ |
120 | struct console_cmdline |
121 | { |
122 | char name[8]; /* Name of the driver */ |
123 | int index; /* Minor dev. to use */ |
124 | char *options; /* Options for the driver */ |
125 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
126 | char *brl_options; /* Options for braille driver */ |
127 | #endif |
128 | }; |
129 | |
130 | #define MAX_CMDLINECONSOLES 8 |
131 | |
132 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; |
133 | static int selected_console = -1; |
134 | static int preferred_console = -1; |
135 | int console_set_on_cmdline; |
136 | EXPORT_SYMBOL(console_set_on_cmdline); |
137 | |
138 | /* Flag: console code may call schedule() */ |
139 | static int console_may_schedule; |
140 | |
141 | #ifdef CONFIG_PRINTK |
142 | |
143 | static char __log_buf[__LOG_BUF_LEN]; |
144 | static char *log_buf = __log_buf; |
145 | static int log_buf_len = __LOG_BUF_LEN; |
146 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
147 | static int saved_console_loglevel = -1; |
148 | |
149 | #ifdef CONFIG_KEXEC |
150 | /* |
151 | * This appends the listed symbols to /proc/vmcoreinfo |
152 | * |
153 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to |
154 | * obtain access to symbols that are otherwise very difficult to locate. These |
155 | * symbols are specifically used so that utilities can access and extract the |
156 | * dmesg log from a vmcore file after a crash. |
157 | */ |
158 | void log_buf_kexec_setup(void) |
159 | { |
160 | VMCOREINFO_SYMBOL(log_buf); |
161 | VMCOREINFO_SYMBOL(log_end); |
162 | VMCOREINFO_SYMBOL(log_buf_len); |
163 | VMCOREINFO_SYMBOL(logged_chars); |
164 | } |
165 | #endif |
166 | |
167 | static int __init log_buf_len_setup(char *str) |
168 | { |
169 | unsigned size = memparse(str, &str); |
170 | unsigned long flags; |
171 | |
172 | if (size) |
173 | size = roundup_pow_of_two(size); |
174 | if (size > log_buf_len) { |
175 | unsigned start, dest_idx, offset; |
176 | char *new_log_buf; |
177 | |
178 | new_log_buf = alloc_bootmem(size); |
179 | if (!new_log_buf) { |
180 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
181 | goto out; |
182 | } |
183 | |
184 | spin_lock_irqsave(&logbuf_lock, flags); |
185 | log_buf_len = size; |
186 | log_buf = new_log_buf; |
187 | |
188 | offset = start = min(con_start, log_start); |
189 | dest_idx = 0; |
190 | while (start != log_end) { |
191 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; |
192 | start++; |
193 | dest_idx++; |
194 | } |
195 | log_start -= offset; |
196 | con_start -= offset; |
197 | log_end -= offset; |
198 | spin_unlock_irqrestore(&logbuf_lock, flags); |
199 | |
200 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
201 | } |
202 | out: |
203 | return 1; |
204 | } |
205 | |
206 | __setup("log_buf_len=", log_buf_len_setup); |
207 | |
208 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
209 | |
210 | static unsigned int boot_delay; /* msecs delay after each printk during bootup */ |
211 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
212 | |
213 | static int __init boot_delay_setup(char *str) |
214 | { |
215 | unsigned long lpj; |
216 | |
217 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ |
218 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; |
219 | |
220 | get_option(&str, &boot_delay); |
221 | if (boot_delay > 10 * 1000) |
222 | boot_delay = 0; |
223 | |
224 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
225 | "HZ: %d, loops_per_msec: %llu\n", |
226 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); |
227 | return 1; |
228 | } |
229 | __setup("boot_delay=", boot_delay_setup); |
230 | |
231 | static void boot_delay_msec(void) |
232 | { |
233 | unsigned long long k; |
234 | unsigned long timeout; |
235 | |
236 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) |
237 | return; |
238 | |
239 | k = (unsigned long long)loops_per_msec * boot_delay; |
240 | |
241 | timeout = jiffies + msecs_to_jiffies(boot_delay); |
242 | while (k) { |
243 | k--; |
244 | cpu_relax(); |
245 | /* |
246 | * use (volatile) jiffies to prevent |
247 | * compiler reduction; loop termination via jiffies |
248 | * is secondary and may or may not happen. |
249 | */ |
250 | if (time_after(jiffies, timeout)) |
251 | break; |
252 | touch_nmi_watchdog(); |
253 | } |
254 | } |
255 | #else |
256 | static inline void boot_delay_msec(void) |
257 | { |
258 | } |
259 | #endif |
260 | |
261 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
262 | { |
263 | unsigned i, j, limit, count; |
264 | int do_clear = 0; |
265 | char c; |
266 | int error = 0; |
267 | |
268 | error = security_syslog(type, from_file); |
269 | if (error) |
270 | return error; |
271 | |
272 | switch (type) { |
273 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
274 | break; |
275 | case SYSLOG_ACTION_OPEN: /* Open log */ |
276 | break; |
277 | case SYSLOG_ACTION_READ: /* Read from log */ |
278 | error = -EINVAL; |
279 | if (!buf || len < 0) |
280 | goto out; |
281 | error = 0; |
282 | if (!len) |
283 | goto out; |
284 | if (!access_ok(VERIFY_WRITE, buf, len)) { |
285 | error = -EFAULT; |
286 | goto out; |
287 | } |
288 | error = wait_event_interruptible(log_wait, |
289 | (log_start - log_end)); |
290 | if (error) |
291 | goto out; |
292 | i = 0; |
293 | spin_lock_irq(&logbuf_lock); |
294 | while (!error && (log_start != log_end) && i < len) { |
295 | c = LOG_BUF(log_start); |
296 | log_start++; |
297 | spin_unlock_irq(&logbuf_lock); |
298 | error = __put_user(c,buf); |
299 | buf++; |
300 | i++; |
301 | cond_resched(); |
302 | spin_lock_irq(&logbuf_lock); |
303 | } |
304 | spin_unlock_irq(&logbuf_lock); |
305 | if (!error) |
306 | error = i; |
307 | break; |
308 | /* Read/clear last kernel messages */ |
309 | case SYSLOG_ACTION_READ_CLEAR: |
310 | do_clear = 1; |
311 | /* FALL THRU */ |
312 | /* Read last kernel messages */ |
313 | case SYSLOG_ACTION_READ_ALL: |
314 | error = -EINVAL; |
315 | if (!buf || len < 0) |
316 | goto out; |
317 | error = 0; |
318 | if (!len) |
319 | goto out; |
320 | if (!access_ok(VERIFY_WRITE, buf, len)) { |
321 | error = -EFAULT; |
322 | goto out; |
323 | } |
324 | count = len; |
325 | if (count > log_buf_len) |
326 | count = log_buf_len; |
327 | spin_lock_irq(&logbuf_lock); |
328 | if (count > logged_chars) |
329 | count = logged_chars; |
330 | if (do_clear) |
331 | logged_chars = 0; |
332 | limit = log_end; |
333 | /* |
334 | * __put_user() could sleep, and while we sleep |
335 | * printk() could overwrite the messages |
336 | * we try to copy to user space. Therefore |
337 | * the messages are copied in reverse. <manfreds> |
338 | */ |
339 | for (i = 0; i < count && !error; i++) { |
340 | j = limit-1-i; |
341 | if (j + log_buf_len < log_end) |
342 | break; |
343 | c = LOG_BUF(j); |
344 | spin_unlock_irq(&logbuf_lock); |
345 | error = __put_user(c,&buf[count-1-i]); |
346 | cond_resched(); |
347 | spin_lock_irq(&logbuf_lock); |
348 | } |
349 | spin_unlock_irq(&logbuf_lock); |
350 | if (error) |
351 | break; |
352 | error = i; |
353 | if (i != count) { |
354 | int offset = count-error; |
355 | /* buffer overflow during copy, correct user buffer. */ |
356 | for (i = 0; i < error; i++) { |
357 | if (__get_user(c,&buf[i+offset]) || |
358 | __put_user(c,&buf[i])) { |
359 | error = -EFAULT; |
360 | break; |
361 | } |
362 | cond_resched(); |
363 | } |
364 | } |
365 | break; |
366 | /* Clear ring buffer */ |
367 | case SYSLOG_ACTION_CLEAR: |
368 | logged_chars = 0; |
369 | break; |
370 | /* Disable logging to console */ |
371 | case SYSLOG_ACTION_CONSOLE_OFF: |
372 | if (saved_console_loglevel == -1) |
373 | saved_console_loglevel = console_loglevel; |
374 | console_loglevel = minimum_console_loglevel; |
375 | break; |
376 | /* Enable logging to console */ |
377 | case SYSLOG_ACTION_CONSOLE_ON: |
378 | if (saved_console_loglevel != -1) { |
379 | console_loglevel = saved_console_loglevel; |
380 | saved_console_loglevel = -1; |
381 | } |
382 | break; |
383 | /* Set level of messages printed to console */ |
384 | case SYSLOG_ACTION_CONSOLE_LEVEL: |
385 | error = -EINVAL; |
386 | if (len < 1 || len > 8) |
387 | goto out; |
388 | if (len < minimum_console_loglevel) |
389 | len = minimum_console_loglevel; |
390 | console_loglevel = len; |
391 | /* Implicitly re-enable logging to console */ |
392 | saved_console_loglevel = -1; |
393 | error = 0; |
394 | break; |
395 | /* Number of chars in the log buffer */ |
396 | case SYSLOG_ACTION_SIZE_UNREAD: |
397 | error = log_end - log_start; |
398 | break; |
399 | /* Size of the log buffer */ |
400 | case SYSLOG_ACTION_SIZE_BUFFER: |
401 | error = log_buf_len; |
402 | break; |
403 | default: |
404 | error = -EINVAL; |
405 | break; |
406 | } |
407 | out: |
408 | return error; |
409 | } |
410 | |
411 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
412 | { |
413 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
414 | } |
415 | |
416 | /* |
417 | * Call the console drivers on a range of log_buf |
418 | */ |
419 | static void __call_console_drivers(unsigned start, unsigned end) |
420 | { |
421 | struct console *con; |
422 | |
423 | for_each_console(con) { |
424 | if ((con->flags & CON_ENABLED) && con->write && |
425 | (cpu_online(smp_processor_id()) || |
426 | (con->flags & CON_ANYTIME))) |
427 | con->write(con, &LOG_BUF(start), end - start); |
428 | } |
429 | } |
430 | |
431 | static int __read_mostly ignore_loglevel; |
432 | |
433 | static int __init ignore_loglevel_setup(char *str) |
434 | { |
435 | ignore_loglevel = 1; |
436 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); |
437 | |
438 | return 0; |
439 | } |
440 | |
441 | early_param("ignore_loglevel", ignore_loglevel_setup); |
442 | |
443 | /* |
444 | * Write out chars from start to end - 1 inclusive |
445 | */ |
446 | static void _call_console_drivers(unsigned start, |
447 | unsigned end, int msg_log_level) |
448 | { |
449 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
450 | console_drivers && start != end) { |
451 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { |
452 | /* wrapped write */ |
453 | __call_console_drivers(start & LOG_BUF_MASK, |
454 | log_buf_len); |
455 | __call_console_drivers(0, end & LOG_BUF_MASK); |
456 | } else { |
457 | __call_console_drivers(start, end); |
458 | } |
459 | } |
460 | } |
461 | |
462 | /* |
463 | * Call the console drivers, asking them to write out |
464 | * log_buf[start] to log_buf[end - 1]. |
465 | * The console_sem must be held. |
466 | */ |
467 | static void call_console_drivers(unsigned start, unsigned end) |
468 | { |
469 | unsigned cur_index, start_print; |
470 | static int msg_level = -1; |
471 | |
472 | BUG_ON(((int)(start - end)) > 0); |
473 | |
474 | cur_index = start; |
475 | start_print = start; |
476 | while (cur_index != end) { |
477 | if (msg_level < 0 && ((end - cur_index) > 2) && |
478 | LOG_BUF(cur_index + 0) == '<' && |
479 | LOG_BUF(cur_index + 1) >= '0' && |
480 | LOG_BUF(cur_index + 1) <= '7' && |
481 | LOG_BUF(cur_index + 2) == '>') { |
482 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
483 | cur_index += 3; |
484 | start_print = cur_index; |
485 | } |
486 | while (cur_index != end) { |
487 | char c = LOG_BUF(cur_index); |
488 | |
489 | cur_index++; |
490 | if (c == '\n') { |
491 | if (msg_level < 0) { |
492 | /* |
493 | * printk() has already given us loglevel tags in |
494 | * the buffer. This code is here in case the |
495 | * log buffer has wrapped right round and scribbled |
496 | * on those tags |
497 | */ |
498 | msg_level = default_message_loglevel; |
499 | } |
500 | _call_console_drivers(start_print, cur_index, msg_level); |
501 | msg_level = -1; |
502 | start_print = cur_index; |
503 | break; |
504 | } |
505 | } |
506 | } |
507 | _call_console_drivers(start_print, end, msg_level); |
508 | } |
509 | |
510 | static void emit_log_char(char c) |
511 | { |
512 | LOG_BUF(log_end) = c; |
513 | log_end++; |
514 | if (log_end - log_start > log_buf_len) |
515 | log_start = log_end - log_buf_len; |
516 | if (log_end - con_start > log_buf_len) |
517 | con_start = log_end - log_buf_len; |
518 | if (logged_chars < log_buf_len) |
519 | logged_chars++; |
520 | } |
521 | |
522 | /* |
523 | * Zap console related locks when oopsing. Only zap at most once |
524 | * every 10 seconds, to leave time for slow consoles to print a |
525 | * full oops. |
526 | */ |
527 | static void zap_locks(void) |
528 | { |
529 | static unsigned long oops_timestamp; |
530 | |
531 | if (time_after_eq(jiffies, oops_timestamp) && |
532 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
533 | return; |
534 | |
535 | oops_timestamp = jiffies; |
536 | |
537 | /* If a crash is occurring, make sure we can't deadlock */ |
538 | spin_lock_init(&logbuf_lock); |
539 | /* And make sure that we print immediately */ |
540 | init_MUTEX(&console_sem); |
541 | } |
542 | |
543 | #if defined(CONFIG_PRINTK_TIME) |
544 | static int printk_time = 1; |
545 | #else |
546 | static int printk_time = 0; |
547 | #endif |
548 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
549 | |
550 | /* Check if we have any console registered that can be called early in boot. */ |
551 | static int have_callable_console(void) |
552 | { |
553 | struct console *con; |
554 | |
555 | for_each_console(con) |
556 | if (con->flags & CON_ANYTIME) |
557 | return 1; |
558 | |
559 | return 0; |
560 | } |
561 | |
562 | /** |
563 | * printk - print a kernel message |
564 | * @fmt: format string |
565 | * |
566 | * This is printk(). It can be called from any context. We want it to work. |
567 | * |
568 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
569 | * call the console drivers. If we fail to get the semaphore we place the output |
570 | * into the log buffer and return. The current holder of the console_sem will |
571 | * notice the new output in release_console_sem() and will send it to the |
572 | * consoles before releasing the semaphore. |
573 | * |
574 | * One effect of this deferred printing is that code which calls printk() and |
575 | * then changes console_loglevel may break. This is because console_loglevel |
576 | * is inspected when the actual printing occurs. |
577 | * |
578 | * See also: |
579 | * printf(3) |
580 | * |
581 | * See the vsnprintf() documentation for format string extensions over C99. |
582 | */ |
583 | |
584 | asmlinkage int printk(const char *fmt, ...) |
585 | { |
586 | va_list args; |
587 | int r; |
588 | |
589 | va_start(args, fmt); |
590 | r = vprintk(fmt, args); |
591 | va_end(args); |
592 | |
593 | return r; |
594 | } |
595 | |
596 | /* cpu currently holding logbuf_lock */ |
597 | static volatile unsigned int printk_cpu = UINT_MAX; |
598 | |
599 | /* |
600 | * Can we actually use the console at this time on this cpu? |
601 | * |
602 | * Console drivers may assume that per-cpu resources have |
603 | * been allocated. So unless they're explicitly marked as |
604 | * being able to cope (CON_ANYTIME) don't call them until |
605 | * this CPU is officially up. |
606 | */ |
607 | static inline int can_use_console(unsigned int cpu) |
608 | { |
609 | return cpu_online(cpu) || have_callable_console(); |
610 | } |
611 | |
612 | /* |
613 | * Try to get console ownership to actually show the kernel |
614 | * messages from a 'printk'. Return true (and with the |
615 | * console_semaphore held, and 'console_locked' set) if it |
616 | * is successful, false otherwise. |
617 | * |
618 | * This gets called with the 'logbuf_lock' spinlock held and |
619 | * interrupts disabled. It should return with 'lockbuf_lock' |
620 | * released but interrupts still disabled. |
621 | */ |
622 | static int acquire_console_semaphore_for_printk(unsigned int cpu) |
623 | { |
624 | int retval = 0; |
625 | |
626 | if (!try_acquire_console_sem()) { |
627 | retval = 1; |
628 | |
629 | /* |
630 | * If we can't use the console, we need to release |
631 | * the console semaphore by hand to avoid flushing |
632 | * the buffer. We need to hold the console semaphore |
633 | * in order to do this test safely. |
634 | */ |
635 | if (!can_use_console(cpu)) { |
636 | console_locked = 0; |
637 | up(&console_sem); |
638 | retval = 0; |
639 | } |
640 | } |
641 | printk_cpu = UINT_MAX; |
642 | spin_unlock(&logbuf_lock); |
643 | return retval; |
644 | } |
645 | static const char recursion_bug_msg [] = |
646 | KERN_CRIT "BUG: recent printk recursion!\n"; |
647 | static int recursion_bug; |
648 | static int new_text_line = 1; |
649 | static char printk_buf[1024]; |
650 | |
651 | int printk_delay_msec __read_mostly; |
652 | |
653 | static inline void printk_delay(void) |
654 | { |
655 | if (unlikely(printk_delay_msec)) { |
656 | int m = printk_delay_msec; |
657 | |
658 | while (m--) { |
659 | mdelay(1); |
660 | touch_nmi_watchdog(); |
661 | } |
662 | } |
663 | } |
664 | |
665 | asmlinkage int vprintk(const char *fmt, va_list args) |
666 | { |
667 | int printed_len = 0; |
668 | int current_log_level = default_message_loglevel; |
669 | unsigned long flags; |
670 | int this_cpu; |
671 | char *p; |
672 | |
673 | boot_delay_msec(); |
674 | printk_delay(); |
675 | |
676 | preempt_disable(); |
677 | /* This stops the holder of console_sem just where we want him */ |
678 | raw_local_irq_save(flags); |
679 | this_cpu = smp_processor_id(); |
680 | |
681 | /* |
682 | * Ouch, printk recursed into itself! |
683 | */ |
684 | if (unlikely(printk_cpu == this_cpu)) { |
685 | /* |
686 | * If a crash is occurring during printk() on this CPU, |
687 | * then try to get the crash message out but make sure |
688 | * we can't deadlock. Otherwise just return to avoid the |
689 | * recursion and return - but flag the recursion so that |
690 | * it can be printed at the next appropriate moment: |
691 | */ |
692 | if (!oops_in_progress) { |
693 | recursion_bug = 1; |
694 | goto out_restore_irqs; |
695 | } |
696 | zap_locks(); |
697 | } |
698 | |
699 | lockdep_off(); |
700 | spin_lock(&logbuf_lock); |
701 | printk_cpu = this_cpu; |
702 | |
703 | if (recursion_bug) { |
704 | recursion_bug = 0; |
705 | strcpy(printk_buf, recursion_bug_msg); |
706 | printed_len = strlen(recursion_bug_msg); |
707 | } |
708 | /* Emit the output into the temporary buffer */ |
709 | printed_len += vscnprintf(printk_buf + printed_len, |
710 | sizeof(printk_buf) - printed_len, fmt, args); |
711 | |
712 | |
713 | p = printk_buf; |
714 | |
715 | /* Do we have a loglevel in the string? */ |
716 | if (p[0] == '<') { |
717 | unsigned char c = p[1]; |
718 | if (c && p[2] == '>') { |
719 | switch (c) { |
720 | case '0' ... '7': /* loglevel */ |
721 | current_log_level = c - '0'; |
722 | /* Fallthrough - make sure we're on a new line */ |
723 | case 'd': /* KERN_DEFAULT */ |
724 | if (!new_text_line) { |
725 | emit_log_char('\n'); |
726 | new_text_line = 1; |
727 | } |
728 | /* Fallthrough - skip the loglevel */ |
729 | case 'c': /* KERN_CONT */ |
730 | p += 3; |
731 | break; |
732 | } |
733 | } |
734 | } |
735 | |
736 | /* |
737 | * Copy the output into log_buf. If the caller didn't provide |
738 | * appropriate log level tags, we insert them here |
739 | */ |
740 | for ( ; *p; p++) { |
741 | if (new_text_line) { |
742 | /* Always output the token */ |
743 | emit_log_char('<'); |
744 | emit_log_char(current_log_level + '0'); |
745 | emit_log_char('>'); |
746 | printed_len += 3; |
747 | new_text_line = 0; |
748 | |
749 | if (printk_time) { |
750 | /* Follow the token with the time */ |
751 | char tbuf[50], *tp; |
752 | unsigned tlen; |
753 | unsigned long long t; |
754 | unsigned long nanosec_rem; |
755 | |
756 | t = cpu_clock(printk_cpu); |
757 | nanosec_rem = do_div(t, 1000000000); |
758 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
759 | (unsigned long) t, |
760 | nanosec_rem / 1000); |
761 | |
762 | for (tp = tbuf; tp < tbuf + tlen; tp++) |
763 | emit_log_char(*tp); |
764 | printed_len += tlen; |
765 | } |
766 | |
767 | if (!*p) |
768 | break; |
769 | } |
770 | |
771 | emit_log_char(*p); |
772 | if (*p == '\n') |
773 | new_text_line = 1; |
774 | } |
775 | |
776 | /* |
777 | * Try to acquire and then immediately release the |
778 | * console semaphore. The release will do all the |
779 | * actual magic (print out buffers, wake up klogd, |
780 | * etc). |
781 | * |
782 | * The acquire_console_semaphore_for_printk() function |
783 | * will release 'logbuf_lock' regardless of whether it |
784 | * actually gets the semaphore or not. |
785 | */ |
786 | if (acquire_console_semaphore_for_printk(this_cpu)) |
787 | release_console_sem(); |
788 | |
789 | lockdep_on(); |
790 | out_restore_irqs: |
791 | raw_local_irq_restore(flags); |
792 | |
793 | preempt_enable(); |
794 | return printed_len; |
795 | } |
796 | EXPORT_SYMBOL(printk); |
797 | EXPORT_SYMBOL(vprintk); |
798 | |
799 | #else |
800 | |
801 | static void call_console_drivers(unsigned start, unsigned end) |
802 | { |
803 | } |
804 | |
805 | #endif |
806 | |
807 | static int __add_preferred_console(char *name, int idx, char *options, |
808 | char *brl_options) |
809 | { |
810 | struct console_cmdline *c; |
811 | int i; |
812 | |
813 | /* |
814 | * See if this tty is not yet registered, and |
815 | * if we have a slot free. |
816 | */ |
817 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
818 | if (strcmp(console_cmdline[i].name, name) == 0 && |
819 | console_cmdline[i].index == idx) { |
820 | if (!brl_options) |
821 | selected_console = i; |
822 | return 0; |
823 | } |
824 | if (i == MAX_CMDLINECONSOLES) |
825 | return -E2BIG; |
826 | if (!brl_options) |
827 | selected_console = i; |
828 | c = &console_cmdline[i]; |
829 | strlcpy(c->name, name, sizeof(c->name)); |
830 | c->options = options; |
831 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
832 | c->brl_options = brl_options; |
833 | #endif |
834 | c->index = idx; |
835 | return 0; |
836 | } |
837 | /* |
838 | * Set up a list of consoles. Called from init/main.c |
839 | */ |
840 | static int __init console_setup(char *str) |
841 | { |
842 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
843 | char *s, *options, *brl_options = NULL; |
844 | int idx; |
845 | |
846 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
847 | if (!memcmp(str, "brl,", 4)) { |
848 | brl_options = ""; |
849 | str += 4; |
850 | } else if (!memcmp(str, "brl=", 4)) { |
851 | brl_options = str + 4; |
852 | str = strchr(brl_options, ','); |
853 | if (!str) { |
854 | printk(KERN_ERR "need port name after brl=\n"); |
855 | return 1; |
856 | } |
857 | *(str++) = 0; |
858 | } |
859 | #endif |
860 | |
861 | /* |
862 | * Decode str into name, index, options. |
863 | */ |
864 | if (str[0] >= '0' && str[0] <= '9') { |
865 | strcpy(buf, "ttyS"); |
866 | strncpy(buf + 4, str, sizeof(buf) - 5); |
867 | } else { |
868 | strncpy(buf, str, sizeof(buf) - 1); |
869 | } |
870 | buf[sizeof(buf) - 1] = 0; |
871 | if ((options = strchr(str, ',')) != NULL) |
872 | *(options++) = 0; |
873 | #ifdef __sparc__ |
874 | if (!strcmp(str, "ttya")) |
875 | strcpy(buf, "ttyS0"); |
876 | if (!strcmp(str, "ttyb")) |
877 | strcpy(buf, "ttyS1"); |
878 | #endif |
879 | for (s = buf; *s; s++) |
880 | if ((*s >= '0' && *s <= '9') || *s == ',') |
881 | break; |
882 | idx = simple_strtoul(s, NULL, 10); |
883 | *s = 0; |
884 | |
885 | __add_preferred_console(buf, idx, options, brl_options); |
886 | console_set_on_cmdline = 1; |
887 | return 1; |
888 | } |
889 | __setup("console=", console_setup); |
890 | |
891 | /** |
892 | * add_preferred_console - add a device to the list of preferred consoles. |
893 | * @name: device name |
894 | * @idx: device index |
895 | * @options: options for this console |
896 | * |
897 | * The last preferred console added will be used for kernel messages |
898 | * and stdin/out/err for init. Normally this is used by console_setup |
899 | * above to handle user-supplied console arguments; however it can also |
900 | * be used by arch-specific code either to override the user or more |
901 | * commonly to provide a default console (ie from PROM variables) when |
902 | * the user has not supplied one. |
903 | */ |
904 | int add_preferred_console(char *name, int idx, char *options) |
905 | { |
906 | return __add_preferred_console(name, idx, options, NULL); |
907 | } |
908 | |
909 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
910 | { |
911 | struct console_cmdline *c; |
912 | int i; |
913 | |
914 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
915 | if (strcmp(console_cmdline[i].name, name) == 0 && |
916 | console_cmdline[i].index == idx) { |
917 | c = &console_cmdline[i]; |
918 | strlcpy(c->name, name_new, sizeof(c->name)); |
919 | c->name[sizeof(c->name) - 1] = 0; |
920 | c->options = options; |
921 | c->index = idx_new; |
922 | return i; |
923 | } |
924 | /* not found */ |
925 | return -1; |
926 | } |
927 | |
928 | int console_suspend_enabled = 1; |
929 | EXPORT_SYMBOL(console_suspend_enabled); |
930 | |
931 | static int __init console_suspend_disable(char *str) |
932 | { |
933 | console_suspend_enabled = 0; |
934 | return 1; |
935 | } |
936 | __setup("no_console_suspend", console_suspend_disable); |
937 | |
938 | /** |
939 | * suspend_console - suspend the console subsystem |
940 | * |
941 | * This disables printk() while we go into suspend states |
942 | */ |
943 | void suspend_console(void) |
944 | { |
945 | if (!console_suspend_enabled) |
946 | return; |
947 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
948 | acquire_console_sem(); |
949 | console_suspended = 1; |
950 | up(&console_sem); |
951 | } |
952 | |
953 | void resume_console(void) |
954 | { |
955 | if (!console_suspend_enabled) |
956 | return; |
957 | down(&console_sem); |
958 | console_suspended = 0; |
959 | release_console_sem(); |
960 | } |
961 | |
962 | /** |
963 | * acquire_console_sem - lock the console system for exclusive use. |
964 | * |
965 | * Acquires a semaphore which guarantees that the caller has |
966 | * exclusive access to the console system and the console_drivers list. |
967 | * |
968 | * Can sleep, returns nothing. |
969 | */ |
970 | void acquire_console_sem(void) |
971 | { |
972 | BUG_ON(in_interrupt()); |
973 | down(&console_sem); |
974 | if (console_suspended) |
975 | return; |
976 | console_locked = 1; |
977 | console_may_schedule = 1; |
978 | } |
979 | EXPORT_SYMBOL(acquire_console_sem); |
980 | |
981 | int try_acquire_console_sem(void) |
982 | { |
983 | if (down_trylock(&console_sem)) |
984 | return -1; |
985 | if (console_suspended) { |
986 | up(&console_sem); |
987 | return -1; |
988 | } |
989 | console_locked = 1; |
990 | console_may_schedule = 0; |
991 | return 0; |
992 | } |
993 | EXPORT_SYMBOL(try_acquire_console_sem); |
994 | |
995 | int is_console_locked(void) |
996 | { |
997 | return console_locked; |
998 | } |
999 | |
1000 | static DEFINE_PER_CPU(int, printk_pending); |
1001 | |
1002 | void printk_tick(void) |
1003 | { |
1004 | if (__get_cpu_var(printk_pending)) { |
1005 | __get_cpu_var(printk_pending) = 0; |
1006 | wake_up_interruptible(&log_wait); |
1007 | } |
1008 | } |
1009 | |
1010 | int printk_needs_cpu(int cpu) |
1011 | { |
1012 | return per_cpu(printk_pending, cpu); |
1013 | } |
1014 | |
1015 | void wake_up_klogd(void) |
1016 | { |
1017 | if (waitqueue_active(&log_wait)) |
1018 | __raw_get_cpu_var(printk_pending) = 1; |
1019 | } |
1020 | |
1021 | /** |
1022 | * release_console_sem - unlock the console system |
1023 | * |
1024 | * Releases the semaphore which the caller holds on the console system |
1025 | * and the console driver list. |
1026 | * |
1027 | * While the semaphore was held, console output may have been buffered |
1028 | * by printk(). If this is the case, release_console_sem() emits |
1029 | * the output prior to releasing the semaphore. |
1030 | * |
1031 | * If there is output waiting for klogd, we wake it up. |
1032 | * |
1033 | * release_console_sem() may be called from any context. |
1034 | */ |
1035 | void release_console_sem(void) |
1036 | { |
1037 | unsigned long flags; |
1038 | unsigned _con_start, _log_end; |
1039 | unsigned wake_klogd = 0; |
1040 | |
1041 | if (console_suspended) { |
1042 | up(&console_sem); |
1043 | return; |
1044 | } |
1045 | |
1046 | console_may_schedule = 0; |
1047 | |
1048 | for ( ; ; ) { |
1049 | spin_lock_irqsave(&logbuf_lock, flags); |
1050 | wake_klogd |= log_start - log_end; |
1051 | if (con_start == log_end) |
1052 | break; /* Nothing to print */ |
1053 | _con_start = con_start; |
1054 | _log_end = log_end; |
1055 | con_start = log_end; /* Flush */ |
1056 | spin_unlock(&logbuf_lock); |
1057 | stop_critical_timings(); /* don't trace print latency */ |
1058 | call_console_drivers(_con_start, _log_end); |
1059 | start_critical_timings(); |
1060 | local_irq_restore(flags); |
1061 | } |
1062 | console_locked = 0; |
1063 | up(&console_sem); |
1064 | spin_unlock_irqrestore(&logbuf_lock, flags); |
1065 | if (wake_klogd) |
1066 | wake_up_klogd(); |
1067 | } |
1068 | EXPORT_SYMBOL(release_console_sem); |
1069 | |
1070 | /** |
1071 | * console_conditional_schedule - yield the CPU if required |
1072 | * |
1073 | * If the console code is currently allowed to sleep, and |
1074 | * if this CPU should yield the CPU to another task, do |
1075 | * so here. |
1076 | * |
1077 | * Must be called within acquire_console_sem(). |
1078 | */ |
1079 | void __sched console_conditional_schedule(void) |
1080 | { |
1081 | if (console_may_schedule) |
1082 | cond_resched(); |
1083 | } |
1084 | EXPORT_SYMBOL(console_conditional_schedule); |
1085 | |
1086 | void console_unblank(void) |
1087 | { |
1088 | struct console *c; |
1089 | |
1090 | /* |
1091 | * console_unblank can no longer be called in interrupt context unless |
1092 | * oops_in_progress is set to 1.. |
1093 | */ |
1094 | if (oops_in_progress) { |
1095 | if (down_trylock(&console_sem) != 0) |
1096 | return; |
1097 | } else |
1098 | acquire_console_sem(); |
1099 | |
1100 | console_locked = 1; |
1101 | console_may_schedule = 0; |
1102 | for_each_console(c) |
1103 | if ((c->flags & CON_ENABLED) && c->unblank) |
1104 | c->unblank(); |
1105 | release_console_sem(); |
1106 | } |
1107 | |
1108 | /* |
1109 | * Return the console tty driver structure and its associated index |
1110 | */ |
1111 | struct tty_driver *console_device(int *index) |
1112 | { |
1113 | struct console *c; |
1114 | struct tty_driver *driver = NULL; |
1115 | |
1116 | acquire_console_sem(); |
1117 | for_each_console(c) { |
1118 | if (!c->device) |
1119 | continue; |
1120 | driver = c->device(c, index); |
1121 | if (driver) |
1122 | break; |
1123 | } |
1124 | release_console_sem(); |
1125 | return driver; |
1126 | } |
1127 | |
1128 | /* |
1129 | * Prevent further output on the passed console device so that (for example) |
1130 | * serial drivers can disable console output before suspending a port, and can |
1131 | * re-enable output afterwards. |
1132 | */ |
1133 | void console_stop(struct console *console) |
1134 | { |
1135 | acquire_console_sem(); |
1136 | console->flags &= ~CON_ENABLED; |
1137 | release_console_sem(); |
1138 | } |
1139 | EXPORT_SYMBOL(console_stop); |
1140 | |
1141 | void console_start(struct console *console) |
1142 | { |
1143 | acquire_console_sem(); |
1144 | console->flags |= CON_ENABLED; |
1145 | release_console_sem(); |
1146 | } |
1147 | EXPORT_SYMBOL(console_start); |
1148 | |
1149 | /* |
1150 | * The console driver calls this routine during kernel initialization |
1151 | * to register the console printing procedure with printk() and to |
1152 | * print any messages that were printed by the kernel before the |
1153 | * console driver was initialized. |
1154 | * |
1155 | * This can happen pretty early during the boot process (because of |
1156 | * early_printk) - sometimes before setup_arch() completes - be careful |
1157 | * of what kernel features are used - they may not be initialised yet. |
1158 | * |
1159 | * There are two types of consoles - bootconsoles (early_printk) and |
1160 | * "real" consoles (everything which is not a bootconsole) which are |
1161 | * handled differently. |
1162 | * - Any number of bootconsoles can be registered at any time. |
1163 | * - As soon as a "real" console is registered, all bootconsoles |
1164 | * will be unregistered automatically. |
1165 | * - Once a "real" console is registered, any attempt to register a |
1166 | * bootconsoles will be rejected |
1167 | */ |
1168 | void register_console(struct console *newcon) |
1169 | { |
1170 | int i; |
1171 | unsigned long flags; |
1172 | struct console *bcon = NULL; |
1173 | |
1174 | /* |
1175 | * before we register a new CON_BOOT console, make sure we don't |
1176 | * already have a valid console |
1177 | */ |
1178 | if (console_drivers && newcon->flags & CON_BOOT) { |
1179 | /* find the last or real console */ |
1180 | for_each_console(bcon) { |
1181 | if (!(bcon->flags & CON_BOOT)) { |
1182 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", |
1183 | newcon->name, newcon->index); |
1184 | return; |
1185 | } |
1186 | } |
1187 | } |
1188 | |
1189 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1190 | bcon = console_drivers; |
1191 | |
1192 | if (preferred_console < 0 || bcon || !console_drivers) |
1193 | preferred_console = selected_console; |
1194 | |
1195 | if (newcon->early_setup) |
1196 | newcon->early_setup(); |
1197 | |
1198 | /* |
1199 | * See if we want to use this console driver. If we |
1200 | * didn't select a console we take the first one |
1201 | * that registers here. |
1202 | */ |
1203 | if (preferred_console < 0) { |
1204 | if (newcon->index < 0) |
1205 | newcon->index = 0; |
1206 | if (newcon->setup == NULL || |
1207 | newcon->setup(newcon, NULL) == 0) { |
1208 | newcon->flags |= CON_ENABLED; |
1209 | if (newcon->device) { |
1210 | newcon->flags |= CON_CONSDEV; |
1211 | preferred_console = 0; |
1212 | } |
1213 | } |
1214 | } |
1215 | |
1216 | /* |
1217 | * See if this console matches one we selected on |
1218 | * the command line. |
1219 | */ |
1220 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1221 | i++) { |
1222 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1223 | continue; |
1224 | if (newcon->index >= 0 && |
1225 | newcon->index != console_cmdline[i].index) |
1226 | continue; |
1227 | if (newcon->index < 0) |
1228 | newcon->index = console_cmdline[i].index; |
1229 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1230 | if (console_cmdline[i].brl_options) { |
1231 | newcon->flags |= CON_BRL; |
1232 | braille_register_console(newcon, |
1233 | console_cmdline[i].index, |
1234 | console_cmdline[i].options, |
1235 | console_cmdline[i].brl_options); |
1236 | return; |
1237 | } |
1238 | #endif |
1239 | if (newcon->setup && |
1240 | newcon->setup(newcon, console_cmdline[i].options) != 0) |
1241 | break; |
1242 | newcon->flags |= CON_ENABLED; |
1243 | newcon->index = console_cmdline[i].index; |
1244 | if (i == selected_console) { |
1245 | newcon->flags |= CON_CONSDEV; |
1246 | preferred_console = selected_console; |
1247 | } |
1248 | break; |
1249 | } |
1250 | |
1251 | if (!(newcon->flags & CON_ENABLED)) |
1252 | return; |
1253 | |
1254 | /* |
1255 | * If we have a bootconsole, and are switching to a real console, |
1256 | * don't print everything out again, since when the boot console, and |
1257 | * the real console are the same physical device, it's annoying to |
1258 | * see the beginning boot messages twice |
1259 | */ |
1260 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) |
1261 | newcon->flags &= ~CON_PRINTBUFFER; |
1262 | |
1263 | /* |
1264 | * Put this console in the list - keep the |
1265 | * preferred driver at the head of the list. |
1266 | */ |
1267 | acquire_console_sem(); |
1268 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1269 | newcon->next = console_drivers; |
1270 | console_drivers = newcon; |
1271 | if (newcon->next) |
1272 | newcon->next->flags &= ~CON_CONSDEV; |
1273 | } else { |
1274 | newcon->next = console_drivers->next; |
1275 | console_drivers->next = newcon; |
1276 | } |
1277 | if (newcon->flags & CON_PRINTBUFFER) { |
1278 | /* |
1279 | * release_console_sem() will print out the buffered messages |
1280 | * for us. |
1281 | */ |
1282 | spin_lock_irqsave(&logbuf_lock, flags); |
1283 | con_start = log_start; |
1284 | spin_unlock_irqrestore(&logbuf_lock, flags); |
1285 | } |
1286 | release_console_sem(); |
1287 | |
1288 | /* |
1289 | * By unregistering the bootconsoles after we enable the real console |
1290 | * we get the "console xxx enabled" message on all the consoles - |
1291 | * boot consoles, real consoles, etc - this is to ensure that end |
1292 | * users know there might be something in the kernel's log buffer that |
1293 | * went to the bootconsole (that they do not see on the real console) |
1294 | */ |
1295 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) { |
1296 | /* we need to iterate through twice, to make sure we print |
1297 | * everything out, before we unregister the console(s) |
1298 | */ |
1299 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", |
1300 | newcon->name, newcon->index); |
1301 | for_each_console(bcon) |
1302 | if (bcon->flags & CON_BOOT) |
1303 | unregister_console(bcon); |
1304 | } else { |
1305 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", |
1306 | (newcon->flags & CON_BOOT) ? "boot" : "" , |
1307 | newcon->name, newcon->index); |
1308 | } |
1309 | } |
1310 | EXPORT_SYMBOL(register_console); |
1311 | |
1312 | int unregister_console(struct console *console) |
1313 | { |
1314 | struct console *a, *b; |
1315 | int res = 1; |
1316 | |
1317 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1318 | if (console->flags & CON_BRL) |
1319 | return braille_unregister_console(console); |
1320 | #endif |
1321 | |
1322 | acquire_console_sem(); |
1323 | if (console_drivers == console) { |
1324 | console_drivers=console->next; |
1325 | res = 0; |
1326 | } else if (console_drivers) { |
1327 | for (a=console_drivers->next, b=console_drivers ; |
1328 | a; b=a, a=b->next) { |
1329 | if (a == console) { |
1330 | b->next = a->next; |
1331 | res = 0; |
1332 | break; |
1333 | } |
1334 | } |
1335 | } |
1336 | |
1337 | /* |
1338 | * If this isn't the last console and it has CON_CONSDEV set, we |
1339 | * need to set it on the next preferred console. |
1340 | */ |
1341 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
1342 | console_drivers->flags |= CON_CONSDEV; |
1343 | |
1344 | release_console_sem(); |
1345 | return res; |
1346 | } |
1347 | EXPORT_SYMBOL(unregister_console); |
1348 | |
1349 | static int __init disable_boot_consoles(void) |
1350 | { |
1351 | struct console *con; |
1352 | |
1353 | for_each_console(con) { |
1354 | if (con->flags & CON_BOOT) { |
1355 | printk(KERN_INFO "turn off boot console %s%d\n", |
1356 | con->name, con->index); |
1357 | unregister_console(con); |
1358 | } |
1359 | } |
1360 | return 0; |
1361 | } |
1362 | late_initcall(disable_boot_consoles); |
1363 | |
1364 | #if defined CONFIG_PRINTK |
1365 | |
1366 | /* |
1367 | * printk rate limiting, lifted from the networking subsystem. |
1368 | * |
1369 | * This enforces a rate limit: not more than 10 kernel messages |
1370 | * every 5s to make a denial-of-service attack impossible. |
1371 | */ |
1372 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1373 | |
1374 | int __printk_ratelimit(const char *func) |
1375 | { |
1376 | return ___ratelimit(&printk_ratelimit_state, func); |
1377 | } |
1378 | EXPORT_SYMBOL(__printk_ratelimit); |
1379 | |
1380 | /** |
1381 | * printk_timed_ratelimit - caller-controlled printk ratelimiting |
1382 | * @caller_jiffies: pointer to caller's state |
1383 | * @interval_msecs: minimum interval between prints |
1384 | * |
1385 | * printk_timed_ratelimit() returns true if more than @interval_msecs |
1386 | * milliseconds have elapsed since the last time printk_timed_ratelimit() |
1387 | * returned true. |
1388 | */ |
1389 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, |
1390 | unsigned int interval_msecs) |
1391 | { |
1392 | if (*caller_jiffies == 0 |
1393 | || !time_in_range(jiffies, *caller_jiffies, |
1394 | *caller_jiffies |
1395 | + msecs_to_jiffies(interval_msecs))) { |
1396 | *caller_jiffies = jiffies; |
1397 | return true; |
1398 | } |
1399 | return false; |
1400 | } |
1401 | EXPORT_SYMBOL(printk_timed_ratelimit); |
1402 | |
1403 | static DEFINE_SPINLOCK(dump_list_lock); |
1404 | static LIST_HEAD(dump_list); |
1405 | |
1406 | /** |
1407 | * kmsg_dump_register - register a kernel log dumper. |
1408 | * @dumper: pointer to the kmsg_dumper structure |
1409 | * |
1410 | * Adds a kernel log dumper to the system. The dump callback in the |
1411 | * structure will be called when the kernel oopses or panics and must be |
1412 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. |
1413 | */ |
1414 | int kmsg_dump_register(struct kmsg_dumper *dumper) |
1415 | { |
1416 | unsigned long flags; |
1417 | int err = -EBUSY; |
1418 | |
1419 | /* The dump callback needs to be set */ |
1420 | if (!dumper->dump) |
1421 | return -EINVAL; |
1422 | |
1423 | spin_lock_irqsave(&dump_list_lock, flags); |
1424 | /* Don't allow registering multiple times */ |
1425 | if (!dumper->registered) { |
1426 | dumper->registered = 1; |
1427 | list_add_tail(&dumper->list, &dump_list); |
1428 | err = 0; |
1429 | } |
1430 | spin_unlock_irqrestore(&dump_list_lock, flags); |
1431 | |
1432 | return err; |
1433 | } |
1434 | EXPORT_SYMBOL_GPL(kmsg_dump_register); |
1435 | |
1436 | /** |
1437 | * kmsg_dump_unregister - unregister a kmsg dumper. |
1438 | * @dumper: pointer to the kmsg_dumper structure |
1439 | * |
1440 | * Removes a dump device from the system. Returns zero on success and |
1441 | * %-EINVAL otherwise. |
1442 | */ |
1443 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) |
1444 | { |
1445 | unsigned long flags; |
1446 | int err = -EINVAL; |
1447 | |
1448 | spin_lock_irqsave(&dump_list_lock, flags); |
1449 | if (dumper->registered) { |
1450 | dumper->registered = 0; |
1451 | list_del(&dumper->list); |
1452 | err = 0; |
1453 | } |
1454 | spin_unlock_irqrestore(&dump_list_lock, flags); |
1455 | |
1456 | return err; |
1457 | } |
1458 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); |
1459 | |
1460 | static const char const *kmsg_reasons[] = { |
1461 | [KMSG_DUMP_OOPS] = "oops", |
1462 | [KMSG_DUMP_PANIC] = "panic", |
1463 | [KMSG_DUMP_KEXEC] = "kexec", |
1464 | }; |
1465 | |
1466 | static const char *kmsg_to_str(enum kmsg_dump_reason reason) |
1467 | { |
1468 | if (reason >= ARRAY_SIZE(kmsg_reasons) || reason < 0) |
1469 | return "unknown"; |
1470 | |
1471 | return kmsg_reasons[reason]; |
1472 | } |
1473 | |
1474 | /** |
1475 | * kmsg_dump - dump kernel log to kernel message dumpers. |
1476 | * @reason: the reason (oops, panic etc) for dumping |
1477 | * |
1478 | * Iterate through each of the dump devices and call the oops/panic |
1479 | * callbacks with the log buffer. |
1480 | */ |
1481 | void kmsg_dump(enum kmsg_dump_reason reason) |
1482 | { |
1483 | unsigned long end; |
1484 | unsigned chars; |
1485 | struct kmsg_dumper *dumper; |
1486 | const char *s1, *s2; |
1487 | unsigned long l1, l2; |
1488 | unsigned long flags; |
1489 | |
1490 | /* Theoretically, the log could move on after we do this, but |
1491 | there's not a lot we can do about that. The new messages |
1492 | will overwrite the start of what we dump. */ |
1493 | spin_lock_irqsave(&logbuf_lock, flags); |
1494 | end = log_end & LOG_BUF_MASK; |
1495 | chars = logged_chars; |
1496 | spin_unlock_irqrestore(&logbuf_lock, flags); |
1497 | |
1498 | if (logged_chars > end) { |
1499 | s1 = log_buf + log_buf_len - logged_chars + end; |
1500 | l1 = logged_chars - end; |
1501 | |
1502 | s2 = log_buf; |
1503 | l2 = end; |
1504 | } else { |
1505 | s1 = ""; |
1506 | l1 = 0; |
1507 | |
1508 | s2 = log_buf + end - logged_chars; |
1509 | l2 = logged_chars; |
1510 | } |
1511 | |
1512 | if (!spin_trylock_irqsave(&dump_list_lock, flags)) { |
1513 | printk(KERN_ERR "dump_kmsg: dump list lock is held during %s, skipping dump\n", |
1514 | kmsg_to_str(reason)); |
1515 | return; |
1516 | } |
1517 | list_for_each_entry(dumper, &dump_list, list) |
1518 | dumper->dump(dumper, reason, s1, l1, s2, l2); |
1519 | spin_unlock_irqrestore(&dump_list_lock, flags); |
1520 | } |
1521 | #endif |
1522 |
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