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Source at commit ec7cab4cbb721bff91ec924ec691efd8daf36579 created 12 years 8 months ago. By Maarten ter Huurne, MIPS: JZ4740: A320: Updated quickstart documentation. | |
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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/kdb.h> |
37 | #include <linux/ratelimit.h> |
38 | #include <linux/kmsg_dump.h> |
39 | #include <linux/syslog.h> |
40 | #include <linux/cpu.h> |
41 | #include <linux/notifier.h> |
42 | #include <linux/rculist.h> |
43 | |
44 | #include <asm/uaccess.h> |
45 | |
46 | /* |
47 | * Architectures can override it: |
48 | */ |
49 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
50 | { |
51 | } |
52 | |
53 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
54 | |
55 | /* printk's without a loglevel use this.. */ |
56 | #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL |
57 | |
58 | /* We show everything that is MORE important than this.. */ |
59 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ |
60 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ |
61 | |
62 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
63 | |
64 | int console_printk[4] = { |
65 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ |
66 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ |
67 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ |
68 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ |
69 | }; |
70 | |
71 | /* |
72 | * Low level drivers may need that to know if they can schedule in |
73 | * their unblank() callback or not. So let's export it. |
74 | */ |
75 | int oops_in_progress; |
76 | EXPORT_SYMBOL(oops_in_progress); |
77 | |
78 | /* |
79 | * console_sem protects the console_drivers list, and also |
80 | * provides serialisation for access to the entire console |
81 | * driver system. |
82 | */ |
83 | static DEFINE_SEMAPHORE(console_sem); |
84 | struct console *console_drivers; |
85 | EXPORT_SYMBOL_GPL(console_drivers); |
86 | |
87 | /* |
88 | * This is used for debugging the mess that is the VT code by |
89 | * keeping track if we have the console semaphore held. It's |
90 | * definitely not the perfect debug tool (we don't know if _WE_ |
91 | * hold it are racing, but it helps tracking those weird code |
92 | * path in the console code where we end up in places I want |
93 | * locked without the console sempahore held |
94 | */ |
95 | static int console_locked, console_suspended; |
96 | |
97 | /* |
98 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars |
99 | * It is also used in interesting ways to provide interlocking in |
100 | * console_unlock();. |
101 | */ |
102 | static DEFINE_SPINLOCK(logbuf_lock); |
103 | |
104 | #define LOG_BUF_MASK (log_buf_len-1) |
105 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
106 | |
107 | /* |
108 | * The indices into log_buf are not constrained to log_buf_len - they |
109 | * must be masked before subscripting |
110 | */ |
111 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
112 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ |
113 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ |
114 | |
115 | /* |
116 | * If exclusive_console is non-NULL then only this console is to be printed to. |
117 | */ |
118 | static struct console *exclusive_console; |
119 | |
120 | /* |
121 | * Array of consoles built from command line options (console=) |
122 | */ |
123 | struct console_cmdline |
124 | { |
125 | char name[8]; /* Name of the driver */ |
126 | int index; /* Minor dev. to use */ |
127 | char *options; /* Options for the driver */ |
128 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
129 | char *brl_options; /* Options for braille driver */ |
130 | #endif |
131 | }; |
132 | |
133 | #define MAX_CMDLINECONSOLES 8 |
134 | |
135 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; |
136 | static int selected_console = -1; |
137 | static int preferred_console = -1; |
138 | int console_set_on_cmdline; |
139 | EXPORT_SYMBOL(console_set_on_cmdline); |
140 | |
141 | /* Flag: console code may call schedule() */ |
142 | static int console_may_schedule; |
143 | |
144 | #ifdef CONFIG_PRINTK |
145 | |
146 | static char __log_buf[__LOG_BUF_LEN]; |
147 | static char *log_buf = __log_buf; |
148 | static int log_buf_len = __LOG_BUF_LEN; |
149 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
150 | static int saved_console_loglevel = -1; |
151 | |
152 | #ifdef CONFIG_KEXEC |
153 | /* |
154 | * This appends the listed symbols to /proc/vmcoreinfo |
155 | * |
156 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to |
157 | * obtain access to symbols that are otherwise very difficult to locate. These |
158 | * symbols are specifically used so that utilities can access and extract the |
159 | * dmesg log from a vmcore file after a crash. |
160 | */ |
161 | void log_buf_kexec_setup(void) |
162 | { |
163 | VMCOREINFO_SYMBOL(log_buf); |
164 | VMCOREINFO_SYMBOL(log_end); |
165 | VMCOREINFO_SYMBOL(log_buf_len); |
166 | VMCOREINFO_SYMBOL(logged_chars); |
167 | } |
168 | #endif |
169 | |
170 | static int __init log_buf_len_setup(char *str) |
171 | { |
172 | unsigned size = memparse(str, &str); |
173 | unsigned long flags; |
174 | |
175 | if (size) |
176 | size = roundup_pow_of_two(size); |
177 | if (size > log_buf_len) { |
178 | unsigned start, dest_idx, offset; |
179 | char *new_log_buf; |
180 | |
181 | new_log_buf = alloc_bootmem(size); |
182 | if (!new_log_buf) { |
183 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
184 | goto out; |
185 | } |
186 | |
187 | spin_lock_irqsave(&logbuf_lock, flags); |
188 | log_buf_len = size; |
189 | log_buf = new_log_buf; |
190 | |
191 | offset = start = min(con_start, log_start); |
192 | dest_idx = 0; |
193 | while (start != log_end) { |
194 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; |
195 | start++; |
196 | dest_idx++; |
197 | } |
198 | log_start -= offset; |
199 | con_start -= offset; |
200 | log_end -= offset; |
201 | spin_unlock_irqrestore(&logbuf_lock, flags); |
202 | |
203 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
204 | } |
205 | out: |
206 | return 1; |
207 | } |
208 | |
209 | __setup("log_buf_len=", log_buf_len_setup); |
210 | |
211 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
212 | |
213 | static int boot_delay; /* msecs delay after each printk during bootup */ |
214 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
215 | |
216 | static int __init boot_delay_setup(char *str) |
217 | { |
218 | unsigned long lpj; |
219 | |
220 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ |
221 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; |
222 | |
223 | get_option(&str, &boot_delay); |
224 | if (boot_delay > 10 * 1000) |
225 | boot_delay = 0; |
226 | |
227 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
228 | "HZ: %d, loops_per_msec: %llu\n", |
229 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); |
230 | return 1; |
231 | } |
232 | __setup("boot_delay=", boot_delay_setup); |
233 | |
234 | static void boot_delay_msec(void) |
235 | { |
236 | unsigned long long k; |
237 | unsigned long timeout; |
238 | |
239 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) |
240 | return; |
241 | |
242 | k = (unsigned long long)loops_per_msec * boot_delay; |
243 | |
244 | timeout = jiffies + msecs_to_jiffies(boot_delay); |
245 | while (k) { |
246 | k--; |
247 | cpu_relax(); |
248 | /* |
249 | * use (volatile) jiffies to prevent |
250 | * compiler reduction; loop termination via jiffies |
251 | * is secondary and may or may not happen. |
252 | */ |
253 | if (time_after(jiffies, timeout)) |
254 | break; |
255 | touch_nmi_watchdog(); |
256 | } |
257 | } |
258 | #else |
259 | static inline void boot_delay_msec(void) |
260 | { |
261 | } |
262 | #endif |
263 | |
264 | #ifdef CONFIG_SECURITY_DMESG_RESTRICT |
265 | int dmesg_restrict = 1; |
266 | #else |
267 | int dmesg_restrict; |
268 | #endif |
269 | |
270 | static int syslog_action_restricted(int type) |
271 | { |
272 | if (dmesg_restrict) |
273 | return 1; |
274 | /* Unless restricted, we allow "read all" and "get buffer size" for everybody */ |
275 | return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; |
276 | } |
277 | |
278 | static int check_syslog_permissions(int type, bool from_file) |
279 | { |
280 | /* |
281 | * If this is from /proc/kmsg and we've already opened it, then we've |
282 | * already done the capabilities checks at open time. |
283 | */ |
284 | if (from_file && type != SYSLOG_ACTION_OPEN) |
285 | return 0; |
286 | |
287 | if (syslog_action_restricted(type)) { |
288 | if (capable(CAP_SYSLOG)) |
289 | return 0; |
290 | /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */ |
291 | if (capable(CAP_SYS_ADMIN)) { |
292 | WARN_ONCE(1, "Attempt to access syslog with CAP_SYS_ADMIN " |
293 | "but no CAP_SYSLOG (deprecated).\n"); |
294 | return 0; |
295 | } |
296 | return -EPERM; |
297 | } |
298 | return 0; |
299 | } |
300 | |
301 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
302 | { |
303 | unsigned i, j, limit, count; |
304 | int do_clear = 0; |
305 | char c; |
306 | int error; |
307 | |
308 | error = check_syslog_permissions(type, from_file); |
309 | if (error) |
310 | goto out; |
311 | |
312 | error = security_syslog(type); |
313 | if (error) |
314 | return error; |
315 | |
316 | switch (type) { |
317 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
318 | break; |
319 | case SYSLOG_ACTION_OPEN: /* Open log */ |
320 | break; |
321 | case SYSLOG_ACTION_READ: /* Read from log */ |
322 | error = -EINVAL; |
323 | if (!buf || len < 0) |
324 | goto out; |
325 | error = 0; |
326 | if (!len) |
327 | goto out; |
328 | if (!access_ok(VERIFY_WRITE, buf, len)) { |
329 | error = -EFAULT; |
330 | goto out; |
331 | } |
332 | error = wait_event_interruptible(log_wait, |
333 | (log_start - log_end)); |
334 | if (error) |
335 | goto out; |
336 | i = 0; |
337 | spin_lock_irq(&logbuf_lock); |
338 | while (!error && (log_start != log_end) && i < len) { |
339 | c = LOG_BUF(log_start); |
340 | log_start++; |
341 | spin_unlock_irq(&logbuf_lock); |
342 | error = __put_user(c,buf); |
343 | buf++; |
344 | i++; |
345 | cond_resched(); |
346 | spin_lock_irq(&logbuf_lock); |
347 | } |
348 | spin_unlock_irq(&logbuf_lock); |
349 | if (!error) |
350 | error = i; |
351 | break; |
352 | /* Read/clear last kernel messages */ |
353 | case SYSLOG_ACTION_READ_CLEAR: |
354 | do_clear = 1; |
355 | /* FALL THRU */ |
356 | /* Read last kernel messages */ |
357 | case SYSLOG_ACTION_READ_ALL: |
358 | error = -EINVAL; |
359 | if (!buf || len < 0) |
360 | goto out; |
361 | error = 0; |
362 | if (!len) |
363 | goto out; |
364 | if (!access_ok(VERIFY_WRITE, buf, len)) { |
365 | error = -EFAULT; |
366 | goto out; |
367 | } |
368 | count = len; |
369 | if (count > log_buf_len) |
370 | count = log_buf_len; |
371 | spin_lock_irq(&logbuf_lock); |
372 | if (count > logged_chars) |
373 | count = logged_chars; |
374 | if (do_clear) |
375 | logged_chars = 0; |
376 | limit = log_end; |
377 | /* |
378 | * __put_user() could sleep, and while we sleep |
379 | * printk() could overwrite the messages |
380 | * we try to copy to user space. Therefore |
381 | * the messages are copied in reverse. <manfreds> |
382 | */ |
383 | for (i = 0; i < count && !error; i++) { |
384 | j = limit-1-i; |
385 | if (j + log_buf_len < log_end) |
386 | break; |
387 | c = LOG_BUF(j); |
388 | spin_unlock_irq(&logbuf_lock); |
389 | error = __put_user(c,&buf[count-1-i]); |
390 | cond_resched(); |
391 | spin_lock_irq(&logbuf_lock); |
392 | } |
393 | spin_unlock_irq(&logbuf_lock); |
394 | if (error) |
395 | break; |
396 | error = i; |
397 | if (i != count) { |
398 | int offset = count-error; |
399 | /* buffer overflow during copy, correct user buffer. */ |
400 | for (i = 0; i < error; i++) { |
401 | if (__get_user(c,&buf[i+offset]) || |
402 | __put_user(c,&buf[i])) { |
403 | error = -EFAULT; |
404 | break; |
405 | } |
406 | cond_resched(); |
407 | } |
408 | } |
409 | break; |
410 | /* Clear ring buffer */ |
411 | case SYSLOG_ACTION_CLEAR: |
412 | logged_chars = 0; |
413 | break; |
414 | /* Disable logging to console */ |
415 | case SYSLOG_ACTION_CONSOLE_OFF: |
416 | if (saved_console_loglevel == -1) |
417 | saved_console_loglevel = console_loglevel; |
418 | console_loglevel = minimum_console_loglevel; |
419 | break; |
420 | /* Enable logging to console */ |
421 | case SYSLOG_ACTION_CONSOLE_ON: |
422 | if (saved_console_loglevel != -1) { |
423 | console_loglevel = saved_console_loglevel; |
424 | saved_console_loglevel = -1; |
425 | } |
426 | break; |
427 | /* Set level of messages printed to console */ |
428 | case SYSLOG_ACTION_CONSOLE_LEVEL: |
429 | error = -EINVAL; |
430 | if (len < 1 || len > 8) |
431 | goto out; |
432 | if (len < minimum_console_loglevel) |
433 | len = minimum_console_loglevel; |
434 | console_loglevel = len; |
435 | /* Implicitly re-enable logging to console */ |
436 | saved_console_loglevel = -1; |
437 | error = 0; |
438 | break; |
439 | /* Number of chars in the log buffer */ |
440 | case SYSLOG_ACTION_SIZE_UNREAD: |
441 | error = log_end - log_start; |
442 | break; |
443 | /* Size of the log buffer */ |
444 | case SYSLOG_ACTION_SIZE_BUFFER: |
445 | error = log_buf_len; |
446 | break; |
447 | default: |
448 | error = -EINVAL; |
449 | break; |
450 | } |
451 | out: |
452 | return error; |
453 | } |
454 | |
455 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
456 | { |
457 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
458 | } |
459 | |
460 | #ifdef CONFIG_KGDB_KDB |
461 | /* kdb dmesg command needs access to the syslog buffer. do_syslog() |
462 | * uses locks so it cannot be used during debugging. Just tell kdb |
463 | * where the start and end of the physical and logical logs are. This |
464 | * is equivalent to do_syslog(3). |
465 | */ |
466 | void kdb_syslog_data(char *syslog_data[4]) |
467 | { |
468 | syslog_data[0] = log_buf; |
469 | syslog_data[1] = log_buf + log_buf_len; |
470 | syslog_data[2] = log_buf + log_end - |
471 | (logged_chars < log_buf_len ? logged_chars : log_buf_len); |
472 | syslog_data[3] = log_buf + log_end; |
473 | } |
474 | #endif /* CONFIG_KGDB_KDB */ |
475 | |
476 | /* |
477 | * Call the console drivers on a range of log_buf |
478 | */ |
479 | static void __call_console_drivers(unsigned start, unsigned end) |
480 | { |
481 | struct console *con; |
482 | |
483 | for_each_console(con) { |
484 | if (exclusive_console && con != exclusive_console) |
485 | continue; |
486 | if ((con->flags & CON_ENABLED) && con->write && |
487 | (cpu_online(smp_processor_id()) || |
488 | (con->flags & CON_ANYTIME))) |
489 | con->write(con, &LOG_BUF(start), end - start); |
490 | } |
491 | } |
492 | |
493 | static int __read_mostly ignore_loglevel; |
494 | |
495 | static int __init ignore_loglevel_setup(char *str) |
496 | { |
497 | ignore_loglevel = 1; |
498 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); |
499 | |
500 | return 0; |
501 | } |
502 | |
503 | early_param("ignore_loglevel", ignore_loglevel_setup); |
504 | |
505 | /* |
506 | * Write out chars from start to end - 1 inclusive |
507 | */ |
508 | static void _call_console_drivers(unsigned start, |
509 | unsigned end, int msg_log_level) |
510 | { |
511 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
512 | console_drivers && start != end) { |
513 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { |
514 | /* wrapped write */ |
515 | __call_console_drivers(start & LOG_BUF_MASK, |
516 | log_buf_len); |
517 | __call_console_drivers(0, end & LOG_BUF_MASK); |
518 | } else { |
519 | __call_console_drivers(start, end); |
520 | } |
521 | } |
522 | } |
523 | |
524 | /* |
525 | * Parse the syslog header <[0-9]*>. The decimal value represents 32bit, the |
526 | * lower 3 bit are the log level, the rest are the log facility. In case |
527 | * userspace passes usual userspace syslog messages to /dev/kmsg or |
528 | * /dev/ttyprintk, the log prefix might contain the facility. Printk needs |
529 | * to extract the correct log level for in-kernel processing, and not mangle |
530 | * the original value. |
531 | * |
532 | * If a prefix is found, the length of the prefix is returned. If 'level' is |
533 | * passed, it will be filled in with the log level without a possible facility |
534 | * value. If 'special' is passed, the special printk prefix chars are accepted |
535 | * and returned. If no valid header is found, 0 is returned and the passed |
536 | * variables are not touched. |
537 | */ |
538 | static size_t log_prefix(const char *p, unsigned int *level, char *special) |
539 | { |
540 | unsigned int lev = 0; |
541 | char sp = '\0'; |
542 | size_t len; |
543 | |
544 | if (p[0] != '<' || !p[1]) |
545 | return 0; |
546 | if (p[2] == '>') { |
547 | /* usual single digit level number or special char */ |
548 | switch (p[1]) { |
549 | case '0' ... '7': |
550 | lev = p[1] - '0'; |
551 | break; |
552 | case 'c': /* KERN_CONT */ |
553 | case 'd': /* KERN_DEFAULT */ |
554 | sp = p[1]; |
555 | break; |
556 | default: |
557 | return 0; |
558 | } |
559 | len = 3; |
560 | } else { |
561 | /* multi digit including the level and facility number */ |
562 | char *endp = NULL; |
563 | |
564 | if (p[1] < '0' && p[1] > '9') |
565 | return 0; |
566 | |
567 | lev = (simple_strtoul(&p[1], &endp, 10) & 7); |
568 | if (endp == NULL || endp[0] != '>') |
569 | return 0; |
570 | len = (endp + 1) - p; |
571 | } |
572 | |
573 | /* do not accept special char if not asked for */ |
574 | if (sp && !special) |
575 | return 0; |
576 | |
577 | if (special) { |
578 | *special = sp; |
579 | /* return special char, do not touch level */ |
580 | if (sp) |
581 | return len; |
582 | } |
583 | |
584 | if (level) |
585 | *level = lev; |
586 | return len; |
587 | } |
588 | |
589 | /* |
590 | * Call the console drivers, asking them to write out |
591 | * log_buf[start] to log_buf[end - 1]. |
592 | * The console_lock must be held. |
593 | */ |
594 | static void call_console_drivers(unsigned start, unsigned end) |
595 | { |
596 | unsigned cur_index, start_print; |
597 | static int msg_level = -1; |
598 | |
599 | BUG_ON(((int)(start - end)) > 0); |
600 | |
601 | cur_index = start; |
602 | start_print = start; |
603 | while (cur_index != end) { |
604 | if (msg_level < 0 && ((end - cur_index) > 2)) { |
605 | /* strip log prefix */ |
606 | cur_index += log_prefix(&LOG_BUF(cur_index), &msg_level, NULL); |
607 | start_print = cur_index; |
608 | } |
609 | while (cur_index != end) { |
610 | char c = LOG_BUF(cur_index); |
611 | |
612 | cur_index++; |
613 | if (c == '\n') { |
614 | if (msg_level < 0) { |
615 | /* |
616 | * printk() has already given us loglevel tags in |
617 | * the buffer. This code is here in case the |
618 | * log buffer has wrapped right round and scribbled |
619 | * on those tags |
620 | */ |
621 | msg_level = default_message_loglevel; |
622 | } |
623 | _call_console_drivers(start_print, cur_index, msg_level); |
624 | msg_level = -1; |
625 | start_print = cur_index; |
626 | break; |
627 | } |
628 | } |
629 | } |
630 | _call_console_drivers(start_print, end, msg_level); |
631 | } |
632 | |
633 | static void emit_log_char(char c) |
634 | { |
635 | LOG_BUF(log_end) = c; |
636 | log_end++; |
637 | if (log_end - log_start > log_buf_len) |
638 | log_start = log_end - log_buf_len; |
639 | if (log_end - con_start > log_buf_len) |
640 | con_start = log_end - log_buf_len; |
641 | if (logged_chars < log_buf_len) |
642 | logged_chars++; |
643 | } |
644 | |
645 | /* |
646 | * Zap console related locks when oopsing. Only zap at most once |
647 | * every 10 seconds, to leave time for slow consoles to print a |
648 | * full oops. |
649 | */ |
650 | static void zap_locks(void) |
651 | { |
652 | static unsigned long oops_timestamp; |
653 | |
654 | if (time_after_eq(jiffies, oops_timestamp) && |
655 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
656 | return; |
657 | |
658 | oops_timestamp = jiffies; |
659 | |
660 | /* If a crash is occurring, make sure we can't deadlock */ |
661 | spin_lock_init(&logbuf_lock); |
662 | /* And make sure that we print immediately */ |
663 | sema_init(&console_sem, 1); |
664 | } |
665 | |
666 | #if defined(CONFIG_PRINTK_TIME) |
667 | static int printk_time = 1; |
668 | #else |
669 | static int printk_time = 0; |
670 | #endif |
671 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
672 | |
673 | /* Check if we have any console registered that can be called early in boot. */ |
674 | static int have_callable_console(void) |
675 | { |
676 | struct console *con; |
677 | |
678 | for_each_console(con) |
679 | if (con->flags & CON_ANYTIME) |
680 | return 1; |
681 | |
682 | return 0; |
683 | } |
684 | |
685 | /** |
686 | * printk - print a kernel message |
687 | * @fmt: format string |
688 | * |
689 | * This is printk(). It can be called from any context. We want it to work. |
690 | * |
691 | * We try to grab the console_lock. If we succeed, it's easy - we log the output and |
692 | * call the console drivers. If we fail to get the semaphore we place the output |
693 | * into the log buffer and return. The current holder of the console_sem will |
694 | * notice the new output in console_unlock(); and will send it to the |
695 | * consoles before releasing the lock. |
696 | * |
697 | * One effect of this deferred printing is that code which calls printk() and |
698 | * then changes console_loglevel may break. This is because console_loglevel |
699 | * is inspected when the actual printing occurs. |
700 | * |
701 | * See also: |
702 | * printf(3) |
703 | * |
704 | * See the vsnprintf() documentation for format string extensions over C99. |
705 | */ |
706 | |
707 | asmlinkage int printk(const char *fmt, ...) |
708 | { |
709 | va_list args; |
710 | int r; |
711 | |
712 | #ifdef CONFIG_KGDB_KDB |
713 | if (unlikely(kdb_trap_printk)) { |
714 | va_start(args, fmt); |
715 | r = vkdb_printf(fmt, args); |
716 | va_end(args); |
717 | return r; |
718 | } |
719 | #endif |
720 | va_start(args, fmt); |
721 | r = vprintk(fmt, args); |
722 | va_end(args); |
723 | |
724 | return r; |
725 | } |
726 | |
727 | /* cpu currently holding logbuf_lock */ |
728 | static volatile unsigned int printk_cpu = UINT_MAX; |
729 | |
730 | /* |
731 | * Can we actually use the console at this time on this cpu? |
732 | * |
733 | * Console drivers may assume that per-cpu resources have |
734 | * been allocated. So unless they're explicitly marked as |
735 | * being able to cope (CON_ANYTIME) don't call them until |
736 | * this CPU is officially up. |
737 | */ |
738 | static inline int can_use_console(unsigned int cpu) |
739 | { |
740 | return cpu_online(cpu) || have_callable_console(); |
741 | } |
742 | |
743 | /* |
744 | * Try to get console ownership to actually show the kernel |
745 | * messages from a 'printk'. Return true (and with the |
746 | * console_lock held, and 'console_locked' set) if it |
747 | * is successful, false otherwise. |
748 | * |
749 | * This gets called with the 'logbuf_lock' spinlock held and |
750 | * interrupts disabled. It should return with 'lockbuf_lock' |
751 | * released but interrupts still disabled. |
752 | */ |
753 | static int console_trylock_for_printk(unsigned int cpu) |
754 | __releases(&logbuf_lock) |
755 | { |
756 | int retval = 0; |
757 | |
758 | if (console_trylock()) { |
759 | retval = 1; |
760 | |
761 | /* |
762 | * If we can't use the console, we need to release |
763 | * the console semaphore by hand to avoid flushing |
764 | * the buffer. We need to hold the console semaphore |
765 | * in order to do this test safely. |
766 | */ |
767 | if (!can_use_console(cpu)) { |
768 | console_locked = 0; |
769 | up(&console_sem); |
770 | retval = 0; |
771 | } |
772 | } |
773 | printk_cpu = UINT_MAX; |
774 | spin_unlock(&logbuf_lock); |
775 | return retval; |
776 | } |
777 | static const char recursion_bug_msg [] = |
778 | KERN_CRIT "BUG: recent printk recursion!\n"; |
779 | static int recursion_bug; |
780 | static int new_text_line = 1; |
781 | static char printk_buf[1024]; |
782 | |
783 | int printk_delay_msec __read_mostly; |
784 | |
785 | static inline void printk_delay(void) |
786 | { |
787 | if (unlikely(printk_delay_msec)) { |
788 | int m = printk_delay_msec; |
789 | |
790 | while (m--) { |
791 | mdelay(1); |
792 | touch_nmi_watchdog(); |
793 | } |
794 | } |
795 | } |
796 | |
797 | asmlinkage int vprintk(const char *fmt, va_list args) |
798 | { |
799 | int printed_len = 0; |
800 | int current_log_level = default_message_loglevel; |
801 | unsigned long flags; |
802 | int this_cpu; |
803 | char *p; |
804 | size_t plen; |
805 | char special; |
806 | |
807 | boot_delay_msec(); |
808 | printk_delay(); |
809 | |
810 | preempt_disable(); |
811 | /* This stops the holder of console_sem just where we want him */ |
812 | raw_local_irq_save(flags); |
813 | this_cpu = smp_processor_id(); |
814 | |
815 | /* |
816 | * Ouch, printk recursed into itself! |
817 | */ |
818 | if (unlikely(printk_cpu == this_cpu)) { |
819 | /* |
820 | * If a crash is occurring during printk() on this CPU, |
821 | * then try to get the crash message out but make sure |
822 | * we can't deadlock. Otherwise just return to avoid the |
823 | * recursion and return - but flag the recursion so that |
824 | * it can be printed at the next appropriate moment: |
825 | */ |
826 | if (!oops_in_progress) { |
827 | recursion_bug = 1; |
828 | goto out_restore_irqs; |
829 | } |
830 | zap_locks(); |
831 | } |
832 | |
833 | lockdep_off(); |
834 | spin_lock(&logbuf_lock); |
835 | printk_cpu = this_cpu; |
836 | |
837 | if (recursion_bug) { |
838 | recursion_bug = 0; |
839 | strcpy(printk_buf, recursion_bug_msg); |
840 | printed_len = strlen(recursion_bug_msg); |
841 | } |
842 | /* Emit the output into the temporary buffer */ |
843 | printed_len += vscnprintf(printk_buf + printed_len, |
844 | sizeof(printk_buf) - printed_len, fmt, args); |
845 | |
846 | p = printk_buf; |
847 | |
848 | /* Read log level and handle special printk prefix */ |
849 | plen = log_prefix(p, ¤t_log_level, &special); |
850 | if (plen) { |
851 | p += plen; |
852 | |
853 | switch (special) { |
854 | case 'c': /* Strip <c> KERN_CONT, continue line */ |
855 | plen = 0; |
856 | break; |
857 | case 'd': /* Strip <d> KERN_DEFAULT, start new line */ |
858 | plen = 0; |
859 | default: |
860 | if (!new_text_line) { |
861 | emit_log_char('\n'); |
862 | new_text_line = 1; |
863 | } |
864 | } |
865 | } |
866 | |
867 | /* |
868 | * Copy the output into log_buf. If the caller didn't provide |
869 | * the appropriate log prefix, we insert them here |
870 | */ |
871 | for (; *p; p++) { |
872 | if (new_text_line) { |
873 | new_text_line = 0; |
874 | |
875 | if (plen) { |
876 | /* Copy original log prefix */ |
877 | int i; |
878 | |
879 | for (i = 0; i < plen; i++) |
880 | emit_log_char(printk_buf[i]); |
881 | printed_len += plen; |
882 | } else { |
883 | /* Add log prefix */ |
884 | emit_log_char('<'); |
885 | emit_log_char(current_log_level + '0'); |
886 | emit_log_char('>'); |
887 | printed_len += 3; |
888 | } |
889 | |
890 | if (printk_time) { |
891 | /* Add the current time stamp */ |
892 | char tbuf[50], *tp; |
893 | unsigned tlen; |
894 | unsigned long long t; |
895 | unsigned long nanosec_rem; |
896 | |
897 | t = cpu_clock(printk_cpu); |
898 | nanosec_rem = do_div(t, 1000000000); |
899 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
900 | (unsigned long) t, |
901 | nanosec_rem / 1000); |
902 | |
903 | for (tp = tbuf; tp < tbuf + tlen; tp++) |
904 | emit_log_char(*tp); |
905 | printed_len += tlen; |
906 | } |
907 | |
908 | if (!*p) |
909 | break; |
910 | } |
911 | |
912 | emit_log_char(*p); |
913 | if (*p == '\n') |
914 | new_text_line = 1; |
915 | } |
916 | |
917 | /* |
918 | * Try to acquire and then immediately release the |
919 | * console semaphore. The release will do all the |
920 | * actual magic (print out buffers, wake up klogd, |
921 | * etc). |
922 | * |
923 | * The console_trylock_for_printk() function |
924 | * will release 'logbuf_lock' regardless of whether it |
925 | * actually gets the semaphore or not. |
926 | */ |
927 | if (console_trylock_for_printk(this_cpu)) |
928 | console_unlock(); |
929 | |
930 | lockdep_on(); |
931 | out_restore_irqs: |
932 | raw_local_irq_restore(flags); |
933 | |
934 | preempt_enable(); |
935 | return printed_len; |
936 | } |
937 | EXPORT_SYMBOL(printk); |
938 | EXPORT_SYMBOL(vprintk); |
939 | |
940 | #else |
941 | |
942 | static void call_console_drivers(unsigned start, unsigned end) |
943 | { |
944 | } |
945 | |
946 | #endif |
947 | |
948 | static int __add_preferred_console(char *name, int idx, char *options, |
949 | char *brl_options) |
950 | { |
951 | struct console_cmdline *c; |
952 | int i; |
953 | |
954 | /* |
955 | * See if this tty is not yet registered, and |
956 | * if we have a slot free. |
957 | */ |
958 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
959 | if (strcmp(console_cmdline[i].name, name) == 0 && |
960 | console_cmdline[i].index == idx) { |
961 | if (!brl_options) |
962 | selected_console = i; |
963 | return 0; |
964 | } |
965 | if (i == MAX_CMDLINECONSOLES) |
966 | return -E2BIG; |
967 | if (!brl_options) |
968 | selected_console = i; |
969 | c = &console_cmdline[i]; |
970 | strlcpy(c->name, name, sizeof(c->name)); |
971 | c->options = options; |
972 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
973 | c->brl_options = brl_options; |
974 | #endif |
975 | c->index = idx; |
976 | return 0; |
977 | } |
978 | /* |
979 | * Set up a list of consoles. Called from init/main.c |
980 | */ |
981 | static int __init console_setup(char *str) |
982 | { |
983 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
984 | char *s, *options, *brl_options = NULL; |
985 | int idx; |
986 | |
987 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
988 | if (!memcmp(str, "brl,", 4)) { |
989 | brl_options = ""; |
990 | str += 4; |
991 | } else if (!memcmp(str, "brl=", 4)) { |
992 | brl_options = str + 4; |
993 | str = strchr(brl_options, ','); |
994 | if (!str) { |
995 | printk(KERN_ERR "need port name after brl=\n"); |
996 | return 1; |
997 | } |
998 | *(str++) = 0; |
999 | } |
1000 | #endif |
1001 | |
1002 | /* |
1003 | * Decode str into name, index, options. |
1004 | */ |
1005 | if (str[0] >= '0' && str[0] <= '9') { |
1006 | strcpy(buf, "ttyS"); |
1007 | strncpy(buf + 4, str, sizeof(buf) - 5); |
1008 | } else { |
1009 | strncpy(buf, str, sizeof(buf) - 1); |
1010 | } |
1011 | buf[sizeof(buf) - 1] = 0; |
1012 | if ((options = strchr(str, ',')) != NULL) |
1013 | *(options++) = 0; |
1014 | #ifdef __sparc__ |
1015 | if (!strcmp(str, "ttya")) |
1016 | strcpy(buf, "ttyS0"); |
1017 | if (!strcmp(str, "ttyb")) |
1018 | strcpy(buf, "ttyS1"); |
1019 | #endif |
1020 | for (s = buf; *s; s++) |
1021 | if ((*s >= '0' && *s <= '9') || *s == ',') |
1022 | break; |
1023 | idx = simple_strtoul(s, NULL, 10); |
1024 | *s = 0; |
1025 | |
1026 | __add_preferred_console(buf, idx, options, brl_options); |
1027 | console_set_on_cmdline = 1; |
1028 | return 1; |
1029 | } |
1030 | __setup("console=", console_setup); |
1031 | |
1032 | /** |
1033 | * add_preferred_console - add a device to the list of preferred consoles. |
1034 | * @name: device name |
1035 | * @idx: device index |
1036 | * @options: options for this console |
1037 | * |
1038 | * The last preferred console added will be used for kernel messages |
1039 | * and stdin/out/err for init. Normally this is used by console_setup |
1040 | * above to handle user-supplied console arguments; however it can also |
1041 | * be used by arch-specific code either to override the user or more |
1042 | * commonly to provide a default console (ie from PROM variables) when |
1043 | * the user has not supplied one. |
1044 | */ |
1045 | int add_preferred_console(char *name, int idx, char *options) |
1046 | { |
1047 | return __add_preferred_console(name, idx, options, NULL); |
1048 | } |
1049 | |
1050 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
1051 | { |
1052 | struct console_cmdline *c; |
1053 | int i; |
1054 | |
1055 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
1056 | if (strcmp(console_cmdline[i].name, name) == 0 && |
1057 | console_cmdline[i].index == idx) { |
1058 | c = &console_cmdline[i]; |
1059 | strlcpy(c->name, name_new, sizeof(c->name)); |
1060 | c->name[sizeof(c->name) - 1] = 0; |
1061 | c->options = options; |
1062 | c->index = idx_new; |
1063 | return i; |
1064 | } |
1065 | /* not found */ |
1066 | return -1; |
1067 | } |
1068 | |
1069 | int console_suspend_enabled = 1; |
1070 | EXPORT_SYMBOL(console_suspend_enabled); |
1071 | |
1072 | static int __init console_suspend_disable(char *str) |
1073 | { |
1074 | console_suspend_enabled = 0; |
1075 | return 1; |
1076 | } |
1077 | __setup("no_console_suspend", console_suspend_disable); |
1078 | |
1079 | /** |
1080 | * suspend_console - suspend the console subsystem |
1081 | * |
1082 | * This disables printk() while we go into suspend states |
1083 | */ |
1084 | void suspend_console(void) |
1085 | { |
1086 | if (!console_suspend_enabled) |
1087 | return; |
1088 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
1089 | console_lock(); |
1090 | console_suspended = 1; |
1091 | up(&console_sem); |
1092 | } |
1093 | |
1094 | void resume_console(void) |
1095 | { |
1096 | if (!console_suspend_enabled) |
1097 | return; |
1098 | down(&console_sem); |
1099 | console_suspended = 0; |
1100 | console_unlock(); |
1101 | } |
1102 | |
1103 | /** |
1104 | * console_cpu_notify - print deferred console messages after CPU hotplug |
1105 | * @self: notifier struct |
1106 | * @action: CPU hotplug event |
1107 | * @hcpu: unused |
1108 | * |
1109 | * If printk() is called from a CPU that is not online yet, the messages |
1110 | * will be spooled but will not show up on the console. This function is |
1111 | * called when a new CPU comes online (or fails to come up), and ensures |
1112 | * that any such output gets printed. |
1113 | */ |
1114 | static int __cpuinit console_cpu_notify(struct notifier_block *self, |
1115 | unsigned long action, void *hcpu) |
1116 | { |
1117 | switch (action) { |
1118 | case CPU_ONLINE: |
1119 | case CPU_DEAD: |
1120 | case CPU_DYING: |
1121 | case CPU_DOWN_FAILED: |
1122 | case CPU_UP_CANCELED: |
1123 | console_lock(); |
1124 | console_unlock(); |
1125 | } |
1126 | return NOTIFY_OK; |
1127 | } |
1128 | |
1129 | /** |
1130 | * console_lock - lock the console system for exclusive use. |
1131 | * |
1132 | * Acquires a lock which guarantees that the caller has |
1133 | * exclusive access to the console system and the console_drivers list. |
1134 | * |
1135 | * Can sleep, returns nothing. |
1136 | */ |
1137 | void console_lock(void) |
1138 | { |
1139 | BUG_ON(in_interrupt()); |
1140 | down(&console_sem); |
1141 | if (console_suspended) |
1142 | return; |
1143 | console_locked = 1; |
1144 | console_may_schedule = 1; |
1145 | } |
1146 | EXPORT_SYMBOL(console_lock); |
1147 | |
1148 | /** |
1149 | * console_trylock - try to lock the console system for exclusive use. |
1150 | * |
1151 | * Tried to acquire a lock which guarantees that the caller has |
1152 | * exclusive access to the console system and the console_drivers list. |
1153 | * |
1154 | * returns 1 on success, and 0 on failure to acquire the lock. |
1155 | */ |
1156 | int console_trylock(void) |
1157 | { |
1158 | if (down_trylock(&console_sem)) |
1159 | return 0; |
1160 | if (console_suspended) { |
1161 | up(&console_sem); |
1162 | return 0; |
1163 | } |
1164 | console_locked = 1; |
1165 | console_may_schedule = 0; |
1166 | return 1; |
1167 | } |
1168 | EXPORT_SYMBOL(console_trylock); |
1169 | |
1170 | int is_console_locked(void) |
1171 | { |
1172 | return console_locked; |
1173 | } |
1174 | |
1175 | static DEFINE_PER_CPU(int, printk_pending); |
1176 | |
1177 | void printk_tick(void) |
1178 | { |
1179 | if (__this_cpu_read(printk_pending)) { |
1180 | __this_cpu_write(printk_pending, 0); |
1181 | wake_up_interruptible(&log_wait); |
1182 | } |
1183 | } |
1184 | |
1185 | int printk_needs_cpu(int cpu) |
1186 | { |
1187 | if (cpu_is_offline(cpu)) |
1188 | printk_tick(); |
1189 | return __this_cpu_read(printk_pending); |
1190 | } |
1191 | |
1192 | void wake_up_klogd(void) |
1193 | { |
1194 | if (waitqueue_active(&log_wait)) |
1195 | this_cpu_write(printk_pending, 1); |
1196 | } |
1197 | |
1198 | /** |
1199 | * console_unlock - unlock the console system |
1200 | * |
1201 | * Releases the console_lock which the caller holds on the console system |
1202 | * and the console driver list. |
1203 | * |
1204 | * While the console_lock was held, console output may have been buffered |
1205 | * by printk(). If this is the case, console_unlock(); emits |
1206 | * the output prior to releasing the lock. |
1207 | * |
1208 | * If there is output waiting for klogd, we wake it up. |
1209 | * |
1210 | * console_unlock(); may be called from any context. |
1211 | */ |
1212 | void console_unlock(void) |
1213 | { |
1214 | unsigned long flags; |
1215 | unsigned _con_start, _log_end; |
1216 | unsigned wake_klogd = 0; |
1217 | |
1218 | if (console_suspended) { |
1219 | up(&console_sem); |
1220 | return; |
1221 | } |
1222 | |
1223 | console_may_schedule = 0; |
1224 | |
1225 | for ( ; ; ) { |
1226 | spin_lock_irqsave(&logbuf_lock, flags); |
1227 | wake_klogd |= log_start - log_end; |
1228 | if (con_start == log_end) |
1229 | break; /* Nothing to print */ |
1230 | _con_start = con_start; |
1231 | _log_end = log_end; |
1232 | con_start = log_end; /* Flush */ |
1233 | spin_unlock(&logbuf_lock); |
1234 | stop_critical_timings(); /* don't trace print latency */ |
1235 | call_console_drivers(_con_start, _log_end); |
1236 | start_critical_timings(); |
1237 | local_irq_restore(flags); |
1238 | } |
1239 | console_locked = 0; |
1240 | |
1241 | /* Release the exclusive_console once it is used */ |
1242 | if (unlikely(exclusive_console)) |
1243 | exclusive_console = NULL; |
1244 | |
1245 | up(&console_sem); |
1246 | spin_unlock_irqrestore(&logbuf_lock, flags); |
1247 | if (wake_klogd) |
1248 | wake_up_klogd(); |
1249 | } |
1250 | EXPORT_SYMBOL(console_unlock); |
1251 | |
1252 | /** |
1253 | * console_conditional_schedule - yield the CPU if required |
1254 | * |
1255 | * If the console code is currently allowed to sleep, and |
1256 | * if this CPU should yield the CPU to another task, do |
1257 | * so here. |
1258 | * |
1259 | * Must be called within console_lock();. |
1260 | */ |
1261 | void __sched console_conditional_schedule(void) |
1262 | { |
1263 | if (console_may_schedule) |
1264 | cond_resched(); |
1265 | } |
1266 | EXPORT_SYMBOL(console_conditional_schedule); |
1267 | |
1268 | void console_unblank(void) |
1269 | { |
1270 | struct console *c; |
1271 | |
1272 | /* |
1273 | * console_unblank can no longer be called in interrupt context unless |
1274 | * oops_in_progress is set to 1.. |
1275 | */ |
1276 | if (oops_in_progress) { |
1277 | if (down_trylock(&console_sem) != 0) |
1278 | return; |
1279 | } else |
1280 | console_lock(); |
1281 | |
1282 | console_locked = 1; |
1283 | console_may_schedule = 0; |
1284 | for_each_console(c) |
1285 | if ((c->flags & CON_ENABLED) && c->unblank) |
1286 | c->unblank(); |
1287 | console_unlock(); |
1288 | } |
1289 | |
1290 | /* |
1291 | * Return the console tty driver structure and its associated index |
1292 | */ |
1293 | struct tty_driver *console_device(int *index) |
1294 | { |
1295 | struct console *c; |
1296 | struct tty_driver *driver = NULL; |
1297 | |
1298 | console_lock(); |
1299 | for_each_console(c) { |
1300 | if (!c->device) |
1301 | continue; |
1302 | driver = c->device(c, index); |
1303 | if (driver) |
1304 | break; |
1305 | } |
1306 | console_unlock(); |
1307 | return driver; |
1308 | } |
1309 | |
1310 | /* |
1311 | * Prevent further output on the passed console device so that (for example) |
1312 | * serial drivers can disable console output before suspending a port, and can |
1313 | * re-enable output afterwards. |
1314 | */ |
1315 | void console_stop(struct console *console) |
1316 | { |
1317 | console_lock(); |
1318 | console->flags &= ~CON_ENABLED; |
1319 | console_unlock(); |
1320 | } |
1321 | EXPORT_SYMBOL(console_stop); |
1322 | |
1323 | void console_start(struct console *console) |
1324 | { |
1325 | console_lock(); |
1326 | console->flags |= CON_ENABLED; |
1327 | console_unlock(); |
1328 | } |
1329 | EXPORT_SYMBOL(console_start); |
1330 | |
1331 | static int __read_mostly keep_bootcon; |
1332 | |
1333 | static int __init keep_bootcon_setup(char *str) |
1334 | { |
1335 | keep_bootcon = 1; |
1336 | printk(KERN_INFO "debug: skip boot console de-registration.\n"); |
1337 | |
1338 | return 0; |
1339 | } |
1340 | |
1341 | early_param("keep_bootcon", keep_bootcon_setup); |
1342 | |
1343 | /* |
1344 | * The console driver calls this routine during kernel initialization |
1345 | * to register the console printing procedure with printk() and to |
1346 | * print any messages that were printed by the kernel before the |
1347 | * console driver was initialized. |
1348 | * |
1349 | * This can happen pretty early during the boot process (because of |
1350 | * early_printk) - sometimes before setup_arch() completes - be careful |
1351 | * of what kernel features are used - they may not be initialised yet. |
1352 | * |
1353 | * There are two types of consoles - bootconsoles (early_printk) and |
1354 | * "real" consoles (everything which is not a bootconsole) which are |
1355 | * handled differently. |
1356 | * - Any number of bootconsoles can be registered at any time. |
1357 | * - As soon as a "real" console is registered, all bootconsoles |
1358 | * will be unregistered automatically. |
1359 | * - Once a "real" console is registered, any attempt to register a |
1360 | * bootconsoles will be rejected |
1361 | */ |
1362 | void register_console(struct console *newcon) |
1363 | { |
1364 | int i; |
1365 | unsigned long flags; |
1366 | struct console *bcon = NULL; |
1367 | |
1368 | /* |
1369 | * before we register a new CON_BOOT console, make sure we don't |
1370 | * already have a valid console |
1371 | */ |
1372 | if (console_drivers && newcon->flags & CON_BOOT) { |
1373 | /* find the last or real console */ |
1374 | for_each_console(bcon) { |
1375 | if (!(bcon->flags & CON_BOOT)) { |
1376 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", |
1377 | newcon->name, newcon->index); |
1378 | return; |
1379 | } |
1380 | } |
1381 | } |
1382 | |
1383 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1384 | bcon = console_drivers; |
1385 | |
1386 | if (preferred_console < 0 || bcon || !console_drivers) |
1387 | preferred_console = selected_console; |
1388 | |
1389 | if (newcon->early_setup) |
1390 | newcon->early_setup(); |
1391 | |
1392 | /* |
1393 | * See if we want to use this console driver. If we |
1394 | * didn't select a console we take the first one |
1395 | * that registers here. |
1396 | */ |
1397 | if (preferred_console < 0) { |
1398 | if (newcon->index < 0) |
1399 | newcon->index = 0; |
1400 | if (newcon->setup == NULL || |
1401 | newcon->setup(newcon, NULL) == 0) { |
1402 | newcon->flags |= CON_ENABLED; |
1403 | if (newcon->device) { |
1404 | newcon->flags |= CON_CONSDEV; |
1405 | preferred_console = 0; |
1406 | } |
1407 | } |
1408 | } |
1409 | |
1410 | /* |
1411 | * See if this console matches one we selected on |
1412 | * the command line. |
1413 | */ |
1414 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1415 | i++) { |
1416 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1417 | continue; |
1418 | if (newcon->index >= 0 && |
1419 | newcon->index != console_cmdline[i].index) |
1420 | continue; |
1421 | if (newcon->index < 0) |
1422 | newcon->index = console_cmdline[i].index; |
1423 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1424 | if (console_cmdline[i].brl_options) { |
1425 | newcon->flags |= CON_BRL; |
1426 | braille_register_console(newcon, |
1427 | console_cmdline[i].index, |
1428 | console_cmdline[i].options, |
1429 | console_cmdline[i].brl_options); |
1430 | return; |
1431 | } |
1432 | #endif |
1433 | if (newcon->setup && |
1434 | newcon->setup(newcon, console_cmdline[i].options) != 0) |
1435 | break; |
1436 | newcon->flags |= CON_ENABLED; |
1437 | newcon->index = console_cmdline[i].index; |
1438 | if (i == selected_console) { |
1439 | newcon->flags |= CON_CONSDEV; |
1440 | preferred_console = selected_console; |
1441 | } |
1442 | break; |
1443 | } |
1444 | |
1445 | if (!(newcon->flags & CON_ENABLED)) |
1446 | return; |
1447 | |
1448 | /* |
1449 | * If we have a bootconsole, and are switching to a real console, |
1450 | * don't print everything out again, since when the boot console, and |
1451 | * the real console are the same physical device, it's annoying to |
1452 | * see the beginning boot messages twice |
1453 | */ |
1454 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) |
1455 | newcon->flags &= ~CON_PRINTBUFFER; |
1456 | |
1457 | /* |
1458 | * Put this console in the list - keep the |
1459 | * preferred driver at the head of the list. |
1460 | */ |
1461 | console_lock(); |
1462 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1463 | newcon->next = console_drivers; |
1464 | console_drivers = newcon; |
1465 | if (newcon->next) |
1466 | newcon->next->flags &= ~CON_CONSDEV; |
1467 | } else { |
1468 | newcon->next = console_drivers->next; |
1469 | console_drivers->next = newcon; |
1470 | } |
1471 | if (newcon->flags & CON_PRINTBUFFER) { |
1472 | /* |
1473 | * console_unlock(); will print out the buffered messages |
1474 | * for us. |
1475 | */ |
1476 | spin_lock_irqsave(&logbuf_lock, flags); |
1477 | con_start = log_start; |
1478 | spin_unlock_irqrestore(&logbuf_lock, flags); |
1479 | /* |
1480 | * We're about to replay the log buffer. Only do this to the |
1481 | * just-registered console to avoid excessive message spam to |
1482 | * the already-registered consoles. |
1483 | */ |
1484 | exclusive_console = newcon; |
1485 | } |
1486 | console_unlock(); |
1487 | console_sysfs_notify(); |
1488 | |
1489 | /* |
1490 | * By unregistering the bootconsoles after we enable the real console |
1491 | * we get the "console xxx enabled" message on all the consoles - |
1492 | * boot consoles, real consoles, etc - this is to ensure that end |
1493 | * users know there might be something in the kernel's log buffer that |
1494 | * went to the bootconsole (that they do not see on the real console) |
1495 | */ |
1496 | if (bcon && |
1497 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && |
1498 | !keep_bootcon) { |
1499 | /* we need to iterate through twice, to make sure we print |
1500 | * everything out, before we unregister the console(s) |
1501 | */ |
1502 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", |
1503 | newcon->name, newcon->index); |
1504 | for_each_console(bcon) |
1505 | if (bcon->flags & CON_BOOT) |
1506 | unregister_console(bcon); |
1507 | } else { |
1508 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", |
1509 | (newcon->flags & CON_BOOT) ? "boot" : "" , |
1510 | newcon->name, newcon->index); |
1511 | } |
1512 | } |
1513 | EXPORT_SYMBOL(register_console); |
1514 | |
1515 | int unregister_console(struct console *console) |
1516 | { |
1517 | struct console *a, *b; |
1518 | int res = 1; |
1519 | |
1520 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1521 | if (console->flags & CON_BRL) |
1522 | return braille_unregister_console(console); |
1523 | #endif |
1524 | |
1525 | console_lock(); |
1526 | if (console_drivers == console) { |
1527 | console_drivers=console->next; |
1528 | res = 0; |
1529 | } else if (console_drivers) { |
1530 | for (a=console_drivers->next, b=console_drivers ; |
1531 | a; b=a, a=b->next) { |
1532 | if (a == console) { |
1533 | b->next = a->next; |
1534 | res = 0; |
1535 | break; |
1536 | } |
1537 | } |
1538 | } |
1539 | |
1540 | /* |
1541 | * If this isn't the last console and it has CON_CONSDEV set, we |
1542 | * need to set it on the next preferred console. |
1543 | */ |
1544 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
1545 | console_drivers->flags |= CON_CONSDEV; |
1546 | |
1547 | console_unlock(); |
1548 | console_sysfs_notify(); |
1549 | return res; |
1550 | } |
1551 | EXPORT_SYMBOL(unregister_console); |
1552 | |
1553 | static int __init printk_late_init(void) |
1554 | { |
1555 | struct console *con; |
1556 | |
1557 | for_each_console(con) { |
1558 | if (con->flags & CON_BOOT) { |
1559 | printk(KERN_INFO "turn off boot console %s%d\n", |
1560 | con->name, con->index); |
1561 | unregister_console(con); |
1562 | } |
1563 | } |
1564 | hotcpu_notifier(console_cpu_notify, 0); |
1565 | return 0; |
1566 | } |
1567 | late_initcall(printk_late_init); |
1568 | |
1569 | #if defined CONFIG_PRINTK |
1570 | |
1571 | /* |
1572 | * printk rate limiting, lifted from the networking subsystem. |
1573 | * |
1574 | * This enforces a rate limit: not more than 10 kernel messages |
1575 | * every 5s to make a denial-of-service attack impossible. |
1576 | */ |
1577 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1578 | |
1579 | int __printk_ratelimit(const char *func) |
1580 | { |
1581 | return ___ratelimit(&printk_ratelimit_state, func); |
1582 | } |
1583 | EXPORT_SYMBOL(__printk_ratelimit); |
1584 | |
1585 | /** |
1586 | * printk_timed_ratelimit - caller-controlled printk ratelimiting |
1587 | * @caller_jiffies: pointer to caller's state |
1588 | * @interval_msecs: minimum interval between prints |
1589 | * |
1590 | * printk_timed_ratelimit() returns true if more than @interval_msecs |
1591 | * milliseconds have elapsed since the last time printk_timed_ratelimit() |
1592 | * returned true. |
1593 | */ |
1594 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, |
1595 | unsigned int interval_msecs) |
1596 | { |
1597 | if (*caller_jiffies == 0 |
1598 | || !time_in_range(jiffies, *caller_jiffies, |
1599 | *caller_jiffies |
1600 | + msecs_to_jiffies(interval_msecs))) { |
1601 | *caller_jiffies = jiffies; |
1602 | return true; |
1603 | } |
1604 | return false; |
1605 | } |
1606 | EXPORT_SYMBOL(printk_timed_ratelimit); |
1607 | |
1608 | static DEFINE_SPINLOCK(dump_list_lock); |
1609 | static LIST_HEAD(dump_list); |
1610 | |
1611 | /** |
1612 | * kmsg_dump_register - register a kernel log dumper. |
1613 | * @dumper: pointer to the kmsg_dumper structure |
1614 | * |
1615 | * Adds a kernel log dumper to the system. The dump callback in the |
1616 | * structure will be called when the kernel oopses or panics and must be |
1617 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. |
1618 | */ |
1619 | int kmsg_dump_register(struct kmsg_dumper *dumper) |
1620 | { |
1621 | unsigned long flags; |
1622 | int err = -EBUSY; |
1623 | |
1624 | /* The dump callback needs to be set */ |
1625 | if (!dumper->dump) |
1626 | return -EINVAL; |
1627 | |
1628 | spin_lock_irqsave(&dump_list_lock, flags); |
1629 | /* Don't allow registering multiple times */ |
1630 | if (!dumper->registered) { |
1631 | dumper->registered = 1; |
1632 | list_add_tail_rcu(&dumper->list, &dump_list); |
1633 | err = 0; |
1634 | } |
1635 | spin_unlock_irqrestore(&dump_list_lock, flags); |
1636 | |
1637 | return err; |
1638 | } |
1639 | EXPORT_SYMBOL_GPL(kmsg_dump_register); |
1640 | |
1641 | /** |
1642 | * kmsg_dump_unregister - unregister a kmsg dumper. |
1643 | * @dumper: pointer to the kmsg_dumper structure |
1644 | * |
1645 | * Removes a dump device from the system. Returns zero on success and |
1646 | * %-EINVAL otherwise. |
1647 | */ |
1648 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) |
1649 | { |
1650 | unsigned long flags; |
1651 | int err = -EINVAL; |
1652 | |
1653 | spin_lock_irqsave(&dump_list_lock, flags); |
1654 | if (dumper->registered) { |
1655 | dumper->registered = 0; |
1656 | list_del_rcu(&dumper->list); |
1657 | err = 0; |
1658 | } |
1659 | spin_unlock_irqrestore(&dump_list_lock, flags); |
1660 | synchronize_rcu(); |
1661 | |
1662 | return err; |
1663 | } |
1664 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); |
1665 | |
1666 | /** |
1667 | * kmsg_dump - dump kernel log to kernel message dumpers. |
1668 | * @reason: the reason (oops, panic etc) for dumping |
1669 | * |
1670 | * Iterate through each of the dump devices and call the oops/panic |
1671 | * callbacks with the log buffer. |
1672 | */ |
1673 | void kmsg_dump(enum kmsg_dump_reason reason) |
1674 | { |
1675 | unsigned long end; |
1676 | unsigned chars; |
1677 | struct kmsg_dumper *dumper; |
1678 | const char *s1, *s2; |
1679 | unsigned long l1, l2; |
1680 | unsigned long flags; |
1681 | |
1682 | /* Theoretically, the log could move on after we do this, but |
1683 | there's not a lot we can do about that. The new messages |
1684 | will overwrite the start of what we dump. */ |
1685 | spin_lock_irqsave(&logbuf_lock, flags); |
1686 | end = log_end & LOG_BUF_MASK; |
1687 | chars = logged_chars; |
1688 | spin_unlock_irqrestore(&logbuf_lock, flags); |
1689 | |
1690 | if (chars > end) { |
1691 | s1 = log_buf + log_buf_len - chars + end; |
1692 | l1 = chars - end; |
1693 | |
1694 | s2 = log_buf; |
1695 | l2 = end; |
1696 | } else { |
1697 | s1 = ""; |
1698 | l1 = 0; |
1699 | |
1700 | s2 = log_buf + end - chars; |
1701 | l2 = chars; |
1702 | } |
1703 | |
1704 | rcu_read_lock(); |
1705 | list_for_each_entry_rcu(dumper, &dump_list, list) |
1706 | dumper->dump(dumper, reason, s1, l1, s2, l2); |
1707 | rcu_read_unlock(); |
1708 | } |
1709 | #endif |
1710 |
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