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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/memblock.h> |
35 | #include <linux/syscalls.h> |
36 | #include <linux/kexec.h> |
37 | #include <linux/kdb.h> |
38 | #include <linux/ratelimit.h> |
39 | #include <linux/kmsg_dump.h> |
40 | #include <linux/syslog.h> |
41 | #include <linux/cpu.h> |
42 | #include <linux/notifier.h> |
43 | #include <linux/rculist.h> |
44 | |
45 | #include <asm/uaccess.h> |
46 | |
47 | /* |
48 | * Architectures can override it: |
49 | */ |
50 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
51 | { |
52 | } |
53 | |
54 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
55 | |
56 | /* printk's without a loglevel use this.. */ |
57 | #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL |
58 | |
59 | /* We show everything that is MORE important than this.. */ |
60 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ |
61 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ |
62 | |
63 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
64 | |
65 | int console_printk[4] = { |
66 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ |
67 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ |
68 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ |
69 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ |
70 | }; |
71 | |
72 | /* |
73 | * Low level drivers may need that to know if they can schedule in |
74 | * their unblank() callback or not. So let's export it. |
75 | */ |
76 | int oops_in_progress; |
77 | EXPORT_SYMBOL(oops_in_progress); |
78 | |
79 | /* |
80 | * console_sem protects the console_drivers list, and also |
81 | * provides serialisation for access to the entire console |
82 | * driver system. |
83 | */ |
84 | static DEFINE_SEMAPHORE(console_sem); |
85 | struct console *console_drivers; |
86 | EXPORT_SYMBOL_GPL(console_drivers); |
87 | |
88 | /* |
89 | * This is used for debugging the mess that is the VT code by |
90 | * keeping track if we have the console semaphore held. It's |
91 | * definitely not the perfect debug tool (we don't know if _WE_ |
92 | * hold it are racing, but it helps tracking those weird code |
93 | * path in the console code where we end up in places I want |
94 | * locked without the console sempahore held |
95 | */ |
96 | static int console_locked, console_suspended; |
97 | |
98 | /* |
99 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars |
100 | * It is also used in interesting ways to provide interlocking in |
101 | * console_unlock();. |
102 | */ |
103 | static DEFINE_SPINLOCK(logbuf_lock); |
104 | |
105 | #define LOG_BUF_MASK (log_buf_len-1) |
106 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
107 | |
108 | /* |
109 | * The indices into log_buf are not constrained to log_buf_len - they |
110 | * must be masked before subscripting |
111 | */ |
112 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
113 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ |
114 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ |
115 | |
116 | /* |
117 | * If exclusive_console is non-NULL then only this console is to be printed to. |
118 | */ |
119 | static struct console *exclusive_console; |
120 | |
121 | /* |
122 | * Array of consoles built from command line options (console=) |
123 | */ |
124 | struct console_cmdline |
125 | { |
126 | char name[8]; /* Name of the driver */ |
127 | int index; /* Minor dev. to use */ |
128 | char *options; /* Options for the driver */ |
129 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
130 | char *brl_options; /* Options for braille driver */ |
131 | #endif |
132 | }; |
133 | |
134 | #define MAX_CMDLINECONSOLES 8 |
135 | |
136 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; |
137 | static int selected_console = -1; |
138 | static int preferred_console = -1; |
139 | int console_set_on_cmdline; |
140 | EXPORT_SYMBOL(console_set_on_cmdline); |
141 | |
142 | /* Flag: console code may call schedule() */ |
143 | static int console_may_schedule; |
144 | |
145 | #ifdef CONFIG_PRINTK |
146 | |
147 | static char __log_buf[__LOG_BUF_LEN]; |
148 | static char *log_buf = __log_buf; |
149 | static int log_buf_len = __LOG_BUF_LEN; |
150 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
151 | static int saved_console_loglevel = -1; |
152 | |
153 | #ifdef CONFIG_KEXEC |
154 | /* |
155 | * This appends the listed symbols to /proc/vmcoreinfo |
156 | * |
157 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to |
158 | * obtain access to symbols that are otherwise very difficult to locate. These |
159 | * symbols are specifically used so that utilities can access and extract the |
160 | * dmesg log from a vmcore file after a crash. |
161 | */ |
162 | void log_buf_kexec_setup(void) |
163 | { |
164 | VMCOREINFO_SYMBOL(log_buf); |
165 | VMCOREINFO_SYMBOL(log_end); |
166 | VMCOREINFO_SYMBOL(log_buf_len); |
167 | VMCOREINFO_SYMBOL(logged_chars); |
168 | } |
169 | #endif |
170 | |
171 | /* requested log_buf_len from kernel cmdline */ |
172 | static unsigned long __initdata new_log_buf_len; |
173 | |
174 | /* save requested log_buf_len since it's too early to process it */ |
175 | static int __init log_buf_len_setup(char *str) |
176 | { |
177 | unsigned size = memparse(str, &str); |
178 | |
179 | if (size) |
180 | size = roundup_pow_of_two(size); |
181 | if (size > log_buf_len) |
182 | new_log_buf_len = size; |
183 | |
184 | return 0; |
185 | } |
186 | early_param("log_buf_len", log_buf_len_setup); |
187 | |
188 | void __init setup_log_buf(int early) |
189 | { |
190 | unsigned long flags; |
191 | unsigned start, dest_idx, offset; |
192 | char *new_log_buf; |
193 | int free; |
194 | |
195 | if (!new_log_buf_len) |
196 | return; |
197 | |
198 | if (early) { |
199 | unsigned long mem; |
200 | |
201 | mem = memblock_alloc(new_log_buf_len, PAGE_SIZE); |
202 | if (mem == MEMBLOCK_ERROR) |
203 | return; |
204 | new_log_buf = __va(mem); |
205 | } else { |
206 | new_log_buf = alloc_bootmem_nopanic(new_log_buf_len); |
207 | } |
208 | |
209 | if (unlikely(!new_log_buf)) { |
210 | pr_err("log_buf_len: %ld bytes not available\n", |
211 | new_log_buf_len); |
212 | return; |
213 | } |
214 | |
215 | spin_lock_irqsave(&logbuf_lock, flags); |
216 | log_buf_len = new_log_buf_len; |
217 | log_buf = new_log_buf; |
218 | new_log_buf_len = 0; |
219 | free = __LOG_BUF_LEN - log_end; |
220 | |
221 | offset = start = min(con_start, log_start); |
222 | dest_idx = 0; |
223 | while (start != log_end) { |
224 | unsigned log_idx_mask = start & (__LOG_BUF_LEN - 1); |
225 | |
226 | log_buf[dest_idx] = __log_buf[log_idx_mask]; |
227 | start++; |
228 | dest_idx++; |
229 | } |
230 | log_start -= offset; |
231 | con_start -= offset; |
232 | log_end -= offset; |
233 | spin_unlock_irqrestore(&logbuf_lock, flags); |
234 | |
235 | pr_info("log_buf_len: %d\n", log_buf_len); |
236 | pr_info("early log buf free: %d(%d%%)\n", |
237 | free, (free * 100) / __LOG_BUF_LEN); |
238 | } |
239 | |
240 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
241 | |
242 | static int boot_delay; /* msecs delay after each printk during bootup */ |
243 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
244 | |
245 | static int __init boot_delay_setup(char *str) |
246 | { |
247 | unsigned long lpj; |
248 | |
249 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ |
250 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; |
251 | |
252 | get_option(&str, &boot_delay); |
253 | if (boot_delay > 10 * 1000) |
254 | boot_delay = 0; |
255 | |
256 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
257 | "HZ: %d, loops_per_msec: %llu\n", |
258 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); |
259 | return 1; |
260 | } |
261 | __setup("boot_delay=", boot_delay_setup); |
262 | |
263 | static void boot_delay_msec(void) |
264 | { |
265 | unsigned long long k; |
266 | unsigned long timeout; |
267 | |
268 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) |
269 | return; |
270 | |
271 | k = (unsigned long long)loops_per_msec * boot_delay; |
272 | |
273 | timeout = jiffies + msecs_to_jiffies(boot_delay); |
274 | while (k) { |
275 | k--; |
276 | cpu_relax(); |
277 | /* |
278 | * use (volatile) jiffies to prevent |
279 | * compiler reduction; loop termination via jiffies |
280 | * is secondary and may or may not happen. |
281 | */ |
282 | if (time_after(jiffies, timeout)) |
283 | break; |
284 | touch_nmi_watchdog(); |
285 | } |
286 | } |
287 | #else |
288 | static inline void boot_delay_msec(void) |
289 | { |
290 | } |
291 | #endif |
292 | |
293 | #ifdef CONFIG_SECURITY_DMESG_RESTRICT |
294 | int dmesg_restrict = 1; |
295 | #else |
296 | int dmesg_restrict; |
297 | #endif |
298 | |
299 | static int syslog_action_restricted(int type) |
300 | { |
301 | if (dmesg_restrict) |
302 | return 1; |
303 | /* Unless restricted, we allow "read all" and "get buffer size" for everybody */ |
304 | return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; |
305 | } |
306 | |
307 | static int check_syslog_permissions(int type, bool from_file) |
308 | { |
309 | /* |
310 | * If this is from /proc/kmsg and we've already opened it, then we've |
311 | * already done the capabilities checks at open time. |
312 | */ |
313 | if (from_file && type != SYSLOG_ACTION_OPEN) |
314 | return 0; |
315 | |
316 | if (syslog_action_restricted(type)) { |
317 | if (capable(CAP_SYSLOG)) |
318 | return 0; |
319 | /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */ |
320 | if (capable(CAP_SYS_ADMIN)) { |
321 | printk_once(KERN_WARNING "%s (%d): " |
322 | "Attempt to access syslog with CAP_SYS_ADMIN " |
323 | "but no CAP_SYSLOG (deprecated).\n", |
324 | current->comm, task_pid_nr(current)); |
325 | return 0; |
326 | } |
327 | return -EPERM; |
328 | } |
329 | return 0; |
330 | } |
331 | |
332 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
333 | { |
334 | unsigned i, j, limit, count; |
335 | int do_clear = 0; |
336 | char c; |
337 | int error; |
338 | |
339 | error = check_syslog_permissions(type, from_file); |
340 | if (error) |
341 | goto out; |
342 | |
343 | error = security_syslog(type); |
344 | if (error) |
345 | return error; |
346 | |
347 | switch (type) { |
348 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
349 | break; |
350 | case SYSLOG_ACTION_OPEN: /* Open log */ |
351 | break; |
352 | case SYSLOG_ACTION_READ: /* Read from log */ |
353 | error = -EINVAL; |
354 | if (!buf || len < 0) |
355 | goto out; |
356 | error = 0; |
357 | if (!len) |
358 | goto out; |
359 | if (!access_ok(VERIFY_WRITE, buf, len)) { |
360 | error = -EFAULT; |
361 | goto out; |
362 | } |
363 | error = wait_event_interruptible(log_wait, |
364 | (log_start - log_end)); |
365 | if (error) |
366 | goto out; |
367 | i = 0; |
368 | spin_lock_irq(&logbuf_lock); |
369 | while (!error && (log_start != log_end) && i < len) { |
370 | c = LOG_BUF(log_start); |
371 | log_start++; |
372 | spin_unlock_irq(&logbuf_lock); |
373 | error = __put_user(c,buf); |
374 | buf++; |
375 | i++; |
376 | cond_resched(); |
377 | spin_lock_irq(&logbuf_lock); |
378 | } |
379 | spin_unlock_irq(&logbuf_lock); |
380 | if (!error) |
381 | error = i; |
382 | break; |
383 | /* Read/clear last kernel messages */ |
384 | case SYSLOG_ACTION_READ_CLEAR: |
385 | do_clear = 1; |
386 | /* FALL THRU */ |
387 | /* Read last kernel messages */ |
388 | case SYSLOG_ACTION_READ_ALL: |
389 | error = -EINVAL; |
390 | if (!buf || len < 0) |
391 | goto out; |
392 | error = 0; |
393 | if (!len) |
394 | goto out; |
395 | if (!access_ok(VERIFY_WRITE, buf, len)) { |
396 | error = -EFAULT; |
397 | goto out; |
398 | } |
399 | count = len; |
400 | if (count > log_buf_len) |
401 | count = log_buf_len; |
402 | spin_lock_irq(&logbuf_lock); |
403 | if (count > logged_chars) |
404 | count = logged_chars; |
405 | if (do_clear) |
406 | logged_chars = 0; |
407 | limit = log_end; |
408 | /* |
409 | * __put_user() could sleep, and while we sleep |
410 | * printk() could overwrite the messages |
411 | * we try to copy to user space. Therefore |
412 | * the messages are copied in reverse. <manfreds> |
413 | */ |
414 | for (i = 0; i < count && !error; i++) { |
415 | j = limit-1-i; |
416 | if (j + log_buf_len < log_end) |
417 | break; |
418 | c = LOG_BUF(j); |
419 | spin_unlock_irq(&logbuf_lock); |
420 | error = __put_user(c,&buf[count-1-i]); |
421 | cond_resched(); |
422 | spin_lock_irq(&logbuf_lock); |
423 | } |
424 | spin_unlock_irq(&logbuf_lock); |
425 | if (error) |
426 | break; |
427 | error = i; |
428 | if (i != count) { |
429 | int offset = count-error; |
430 | /* buffer overflow during copy, correct user buffer. */ |
431 | for (i = 0; i < error; i++) { |
432 | if (__get_user(c,&buf[i+offset]) || |
433 | __put_user(c,&buf[i])) { |
434 | error = -EFAULT; |
435 | break; |
436 | } |
437 | cond_resched(); |
438 | } |
439 | } |
440 | break; |
441 | /* Clear ring buffer */ |
442 | case SYSLOG_ACTION_CLEAR: |
443 | logged_chars = 0; |
444 | break; |
445 | /* Disable logging to console */ |
446 | case SYSLOG_ACTION_CONSOLE_OFF: |
447 | if (saved_console_loglevel == -1) |
448 | saved_console_loglevel = console_loglevel; |
449 | console_loglevel = minimum_console_loglevel; |
450 | break; |
451 | /* Enable logging to console */ |
452 | case SYSLOG_ACTION_CONSOLE_ON: |
453 | if (saved_console_loglevel != -1) { |
454 | console_loglevel = saved_console_loglevel; |
455 | saved_console_loglevel = -1; |
456 | } |
457 | break; |
458 | /* Set level of messages printed to console */ |
459 | case SYSLOG_ACTION_CONSOLE_LEVEL: |
460 | error = -EINVAL; |
461 | if (len < 1 || len > 8) |
462 | goto out; |
463 | if (len < minimum_console_loglevel) |
464 | len = minimum_console_loglevel; |
465 | console_loglevel = len; |
466 | /* Implicitly re-enable logging to console */ |
467 | saved_console_loglevel = -1; |
468 | error = 0; |
469 | break; |
470 | /* Number of chars in the log buffer */ |
471 | case SYSLOG_ACTION_SIZE_UNREAD: |
472 | error = log_end - log_start; |
473 | break; |
474 | /* Size of the log buffer */ |
475 | case SYSLOG_ACTION_SIZE_BUFFER: |
476 | error = log_buf_len; |
477 | break; |
478 | default: |
479 | error = -EINVAL; |
480 | break; |
481 | } |
482 | out: |
483 | return error; |
484 | } |
485 | |
486 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
487 | { |
488 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
489 | } |
490 | |
491 | #ifdef CONFIG_KGDB_KDB |
492 | /* kdb dmesg command needs access to the syslog buffer. do_syslog() |
493 | * uses locks so it cannot be used during debugging. Just tell kdb |
494 | * where the start and end of the physical and logical logs are. This |
495 | * is equivalent to do_syslog(3). |
496 | */ |
497 | void kdb_syslog_data(char *syslog_data[4]) |
498 | { |
499 | syslog_data[0] = log_buf; |
500 | syslog_data[1] = log_buf + log_buf_len; |
501 | syslog_data[2] = log_buf + log_end - |
502 | (logged_chars < log_buf_len ? logged_chars : log_buf_len); |
503 | syslog_data[3] = log_buf + log_end; |
504 | } |
505 | #endif /* CONFIG_KGDB_KDB */ |
506 | |
507 | /* |
508 | * Call the console drivers on a range of log_buf |
509 | */ |
510 | static void __call_console_drivers(unsigned start, unsigned end) |
511 | { |
512 | struct console *con; |
513 | |
514 | for_each_console(con) { |
515 | if (exclusive_console && con != exclusive_console) |
516 | continue; |
517 | if ((con->flags & CON_ENABLED) && con->write && |
518 | (cpu_online(smp_processor_id()) || |
519 | (con->flags & CON_ANYTIME))) |
520 | con->write(con, &LOG_BUF(start), end - start); |
521 | } |
522 | } |
523 | |
524 | static int __read_mostly ignore_loglevel; |
525 | |
526 | static int __init ignore_loglevel_setup(char *str) |
527 | { |
528 | ignore_loglevel = 1; |
529 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); |
530 | |
531 | return 0; |
532 | } |
533 | |
534 | early_param("ignore_loglevel", ignore_loglevel_setup); |
535 | |
536 | /* |
537 | * Write out chars from start to end - 1 inclusive |
538 | */ |
539 | static void _call_console_drivers(unsigned start, |
540 | unsigned end, int msg_log_level) |
541 | { |
542 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
543 | console_drivers && start != end) { |
544 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { |
545 | /* wrapped write */ |
546 | __call_console_drivers(start & LOG_BUF_MASK, |
547 | log_buf_len); |
548 | __call_console_drivers(0, end & LOG_BUF_MASK); |
549 | } else { |
550 | __call_console_drivers(start, end); |
551 | } |
552 | } |
553 | } |
554 | |
555 | /* |
556 | * Parse the syslog header <[0-9]*>. The decimal value represents 32bit, the |
557 | * lower 3 bit are the log level, the rest are the log facility. In case |
558 | * userspace passes usual userspace syslog messages to /dev/kmsg or |
559 | * /dev/ttyprintk, the log prefix might contain the facility. Printk needs |
560 | * to extract the correct log level for in-kernel processing, and not mangle |
561 | * the original value. |
562 | * |
563 | * If a prefix is found, the length of the prefix is returned. If 'level' is |
564 | * passed, it will be filled in with the log level without a possible facility |
565 | * value. If 'special' is passed, the special printk prefix chars are accepted |
566 | * and returned. If no valid header is found, 0 is returned and the passed |
567 | * variables are not touched. |
568 | */ |
569 | static size_t log_prefix(const char *p, unsigned int *level, char *special) |
570 | { |
571 | unsigned int lev = 0; |
572 | char sp = '\0'; |
573 | size_t len; |
574 | |
575 | if (p[0] != '<' || !p[1]) |
576 | return 0; |
577 | if (p[2] == '>') { |
578 | /* usual single digit level number or special char */ |
579 | switch (p[1]) { |
580 | case '0' ... '7': |
581 | lev = p[1] - '0'; |
582 | break; |
583 | case 'c': /* KERN_CONT */ |
584 | case 'd': /* KERN_DEFAULT */ |
585 | sp = p[1]; |
586 | break; |
587 | default: |
588 | return 0; |
589 | } |
590 | len = 3; |
591 | } else { |
592 | /* multi digit including the level and facility number */ |
593 | char *endp = NULL; |
594 | |
595 | if (p[1] < '0' && p[1] > '9') |
596 | return 0; |
597 | |
598 | lev = (simple_strtoul(&p[1], &endp, 10) & 7); |
599 | if (endp == NULL || endp[0] != '>') |
600 | return 0; |
601 | len = (endp + 1) - p; |
602 | } |
603 | |
604 | /* do not accept special char if not asked for */ |
605 | if (sp && !special) |
606 | return 0; |
607 | |
608 | if (special) { |
609 | *special = sp; |
610 | /* return special char, do not touch level */ |
611 | if (sp) |
612 | return len; |
613 | } |
614 | |
615 | if (level) |
616 | *level = lev; |
617 | return len; |
618 | } |
619 | |
620 | /* |
621 | * Call the console drivers, asking them to write out |
622 | * log_buf[start] to log_buf[end - 1]. |
623 | * The console_lock must be held. |
624 | */ |
625 | static void call_console_drivers(unsigned start, unsigned end) |
626 | { |
627 | unsigned cur_index, start_print; |
628 | static int msg_level = -1; |
629 | |
630 | BUG_ON(((int)(start - end)) > 0); |
631 | |
632 | cur_index = start; |
633 | start_print = start; |
634 | while (cur_index != end) { |
635 | if (msg_level < 0 && ((end - cur_index) > 2)) { |
636 | /* strip log prefix */ |
637 | cur_index += log_prefix(&LOG_BUF(cur_index), &msg_level, NULL); |
638 | start_print = cur_index; |
639 | } |
640 | while (cur_index != end) { |
641 | char c = LOG_BUF(cur_index); |
642 | |
643 | cur_index++; |
644 | if (c == '\n') { |
645 | if (msg_level < 0) { |
646 | /* |
647 | * printk() has already given us loglevel tags in |
648 | * the buffer. This code is here in case the |
649 | * log buffer has wrapped right round and scribbled |
650 | * on those tags |
651 | */ |
652 | msg_level = default_message_loglevel; |
653 | } |
654 | _call_console_drivers(start_print, cur_index, msg_level); |
655 | msg_level = -1; |
656 | start_print = cur_index; |
657 | break; |
658 | } |
659 | } |
660 | } |
661 | _call_console_drivers(start_print, end, msg_level); |
662 | } |
663 | |
664 | static void emit_log_char(char c) |
665 | { |
666 | LOG_BUF(log_end) = c; |
667 | log_end++; |
668 | if (log_end - log_start > log_buf_len) |
669 | log_start = log_end - log_buf_len; |
670 | if (log_end - con_start > log_buf_len) |
671 | con_start = log_end - log_buf_len; |
672 | if (logged_chars < log_buf_len) |
673 | logged_chars++; |
674 | } |
675 | |
676 | /* |
677 | * Zap console related locks when oopsing. Only zap at most once |
678 | * every 10 seconds, to leave time for slow consoles to print a |
679 | * full oops. |
680 | */ |
681 | static void zap_locks(void) |
682 | { |
683 | static unsigned long oops_timestamp; |
684 | |
685 | if (time_after_eq(jiffies, oops_timestamp) && |
686 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
687 | return; |
688 | |
689 | oops_timestamp = jiffies; |
690 | |
691 | /* If a crash is occurring, make sure we can't deadlock */ |
692 | spin_lock_init(&logbuf_lock); |
693 | /* And make sure that we print immediately */ |
694 | sema_init(&console_sem, 1); |
695 | } |
696 | |
697 | #if defined(CONFIG_PRINTK_TIME) |
698 | static int printk_time = 1; |
699 | #else |
700 | static int printk_time = 0; |
701 | #endif |
702 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
703 | |
704 | /* Check if we have any console registered that can be called early in boot. */ |
705 | static int have_callable_console(void) |
706 | { |
707 | struct console *con; |
708 | |
709 | for_each_console(con) |
710 | if (con->flags & CON_ANYTIME) |
711 | return 1; |
712 | |
713 | return 0; |
714 | } |
715 | |
716 | /** |
717 | * printk - print a kernel message |
718 | * @fmt: format string |
719 | * |
720 | * This is printk(). It can be called from any context. We want it to work. |
721 | * |
722 | * We try to grab the console_lock. If we succeed, it's easy - we log the output and |
723 | * call the console drivers. If we fail to get the semaphore we place the output |
724 | * into the log buffer and return. The current holder of the console_sem will |
725 | * notice the new output in console_unlock(); and will send it to the |
726 | * consoles before releasing the lock. |
727 | * |
728 | * One effect of this deferred printing is that code which calls printk() and |
729 | * then changes console_loglevel may break. This is because console_loglevel |
730 | * is inspected when the actual printing occurs. |
731 | * |
732 | * See also: |
733 | * printf(3) |
734 | * |
735 | * See the vsnprintf() documentation for format string extensions over C99. |
736 | */ |
737 | |
738 | asmlinkage int printk(const char *fmt, ...) |
739 | { |
740 | va_list args; |
741 | int r; |
742 | |
743 | #ifdef CONFIG_KGDB_KDB |
744 | if (unlikely(kdb_trap_printk)) { |
745 | va_start(args, fmt); |
746 | r = vkdb_printf(fmt, args); |
747 | va_end(args); |
748 | return r; |
749 | } |
750 | #endif |
751 | va_start(args, fmt); |
752 | r = vprintk(fmt, args); |
753 | va_end(args); |
754 | |
755 | return r; |
756 | } |
757 | |
758 | /* cpu currently holding logbuf_lock */ |
759 | static volatile unsigned int printk_cpu = UINT_MAX; |
760 | |
761 | /* |
762 | * Can we actually use the console at this time on this cpu? |
763 | * |
764 | * Console drivers may assume that per-cpu resources have |
765 | * been allocated. So unless they're explicitly marked as |
766 | * being able to cope (CON_ANYTIME) don't call them until |
767 | * this CPU is officially up. |
768 | */ |
769 | static inline int can_use_console(unsigned int cpu) |
770 | { |
771 | return cpu_online(cpu) || have_callable_console(); |
772 | } |
773 | |
774 | /* |
775 | * Try to get console ownership to actually show the kernel |
776 | * messages from a 'printk'. Return true (and with the |
777 | * console_lock held, and 'console_locked' set) if it |
778 | * is successful, false otherwise. |
779 | * |
780 | * This gets called with the 'logbuf_lock' spinlock held and |
781 | * interrupts disabled. It should return with 'lockbuf_lock' |
782 | * released but interrupts still disabled. |
783 | */ |
784 | static int console_trylock_for_printk(unsigned int cpu) |
785 | __releases(&logbuf_lock) |
786 | { |
787 | int retval = 0, wake = 0; |
788 | |
789 | if (console_trylock()) { |
790 | retval = 1; |
791 | |
792 | /* |
793 | * If we can't use the console, we need to release |
794 | * the console semaphore by hand to avoid flushing |
795 | * the buffer. We need to hold the console semaphore |
796 | * in order to do this test safely. |
797 | */ |
798 | if (!can_use_console(cpu)) { |
799 | console_locked = 0; |
800 | wake = 1; |
801 | retval = 0; |
802 | } |
803 | } |
804 | printk_cpu = UINT_MAX; |
805 | spin_unlock(&logbuf_lock); |
806 | if (wake) |
807 | up(&console_sem); |
808 | return retval; |
809 | } |
810 | static const char recursion_bug_msg [] = |
811 | KERN_CRIT "BUG: recent printk recursion!\n"; |
812 | static int recursion_bug; |
813 | static int new_text_line = 1; |
814 | static char printk_buf[1024]; |
815 | |
816 | int printk_delay_msec __read_mostly; |
817 | |
818 | static inline void printk_delay(void) |
819 | { |
820 | if (unlikely(printk_delay_msec)) { |
821 | int m = printk_delay_msec; |
822 | |
823 | while (m--) { |
824 | mdelay(1); |
825 | touch_nmi_watchdog(); |
826 | } |
827 | } |
828 | } |
829 | |
830 | asmlinkage int vprintk(const char *fmt, va_list args) |
831 | { |
832 | int printed_len = 0; |
833 | int current_log_level = default_message_loglevel; |
834 | unsigned long flags; |
835 | int this_cpu; |
836 | char *p; |
837 | size_t plen; |
838 | char special; |
839 | |
840 | boot_delay_msec(); |
841 | printk_delay(); |
842 | |
843 | preempt_disable(); |
844 | /* This stops the holder of console_sem just where we want him */ |
845 | raw_local_irq_save(flags); |
846 | this_cpu = smp_processor_id(); |
847 | |
848 | /* |
849 | * Ouch, printk recursed into itself! |
850 | */ |
851 | if (unlikely(printk_cpu == this_cpu)) { |
852 | /* |
853 | * If a crash is occurring during printk() on this CPU, |
854 | * then try to get the crash message out but make sure |
855 | * we can't deadlock. Otherwise just return to avoid the |
856 | * recursion and return - but flag the recursion so that |
857 | * it can be printed at the next appropriate moment: |
858 | */ |
859 | if (!oops_in_progress) { |
860 | recursion_bug = 1; |
861 | goto out_restore_irqs; |
862 | } |
863 | zap_locks(); |
864 | } |
865 | |
866 | lockdep_off(); |
867 | spin_lock(&logbuf_lock); |
868 | printk_cpu = this_cpu; |
869 | |
870 | if (recursion_bug) { |
871 | recursion_bug = 0; |
872 | strcpy(printk_buf, recursion_bug_msg); |
873 | printed_len = strlen(recursion_bug_msg); |
874 | } |
875 | /* Emit the output into the temporary buffer */ |
876 | printed_len += vscnprintf(printk_buf + printed_len, |
877 | sizeof(printk_buf) - printed_len, fmt, args); |
878 | |
879 | p = printk_buf; |
880 | |
881 | /* Read log level and handle special printk prefix */ |
882 | plen = log_prefix(p, ¤t_log_level, &special); |
883 | if (plen) { |
884 | p += plen; |
885 | |
886 | switch (special) { |
887 | case 'c': /* Strip <c> KERN_CONT, continue line */ |
888 | plen = 0; |
889 | break; |
890 | case 'd': /* Strip <d> KERN_DEFAULT, start new line */ |
891 | plen = 0; |
892 | default: |
893 | if (!new_text_line) { |
894 | emit_log_char('\n'); |
895 | new_text_line = 1; |
896 | } |
897 | } |
898 | } |
899 | |
900 | /* |
901 | * Copy the output into log_buf. If the caller didn't provide |
902 | * the appropriate log prefix, we insert them here |
903 | */ |
904 | for (; *p; p++) { |
905 | if (new_text_line) { |
906 | new_text_line = 0; |
907 | |
908 | if (plen) { |
909 | /* Copy original log prefix */ |
910 | int i; |
911 | |
912 | for (i = 0; i < plen; i++) |
913 | emit_log_char(printk_buf[i]); |
914 | printed_len += plen; |
915 | } else { |
916 | /* Add log prefix */ |
917 | emit_log_char('<'); |
918 | emit_log_char(current_log_level + '0'); |
919 | emit_log_char('>'); |
920 | printed_len += 3; |
921 | } |
922 | |
923 | if (printk_time) { |
924 | /* Add the current time stamp */ |
925 | char tbuf[50], *tp; |
926 | unsigned tlen; |
927 | unsigned long long t; |
928 | unsigned long nanosec_rem; |
929 | |
930 | t = cpu_clock(printk_cpu); |
931 | nanosec_rem = do_div(t, 1000000000); |
932 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
933 | (unsigned long) t, |
934 | nanosec_rem / 1000); |
935 | |
936 | for (tp = tbuf; tp < tbuf + tlen; tp++) |
937 | emit_log_char(*tp); |
938 | printed_len += tlen; |
939 | } |
940 | |
941 | if (!*p) |
942 | break; |
943 | } |
944 | |
945 | emit_log_char(*p); |
946 | if (*p == '\n') |
947 | new_text_line = 1; |
948 | } |
949 | |
950 | /* |
951 | * Try to acquire and then immediately release the |
952 | * console semaphore. The release will do all the |
953 | * actual magic (print out buffers, wake up klogd, |
954 | * etc). |
955 | * |
956 | * The console_trylock_for_printk() function |
957 | * will release 'logbuf_lock' regardless of whether it |
958 | * actually gets the semaphore or not. |
959 | */ |
960 | if (console_trylock_for_printk(this_cpu)) |
961 | console_unlock(); |
962 | |
963 | lockdep_on(); |
964 | out_restore_irqs: |
965 | raw_local_irq_restore(flags); |
966 | |
967 | preempt_enable(); |
968 | return printed_len; |
969 | } |
970 | EXPORT_SYMBOL(printk); |
971 | EXPORT_SYMBOL(vprintk); |
972 | |
973 | #else |
974 | |
975 | static void call_console_drivers(unsigned start, unsigned end) |
976 | { |
977 | } |
978 | |
979 | #endif |
980 | |
981 | static int __add_preferred_console(char *name, int idx, char *options, |
982 | char *brl_options) |
983 | { |
984 | struct console_cmdline *c; |
985 | int i; |
986 | |
987 | /* |
988 | * See if this tty is not yet registered, and |
989 | * if we have a slot free. |
990 | */ |
991 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
992 | if (strcmp(console_cmdline[i].name, name) == 0 && |
993 | console_cmdline[i].index == idx) { |
994 | if (!brl_options) |
995 | selected_console = i; |
996 | return 0; |
997 | } |
998 | if (i == MAX_CMDLINECONSOLES) |
999 | return -E2BIG; |
1000 | if (!brl_options) |
1001 | selected_console = i; |
1002 | c = &console_cmdline[i]; |
1003 | strlcpy(c->name, name, sizeof(c->name)); |
1004 | c->options = options; |
1005 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1006 | c->brl_options = brl_options; |
1007 | #endif |
1008 | c->index = idx; |
1009 | return 0; |
1010 | } |
1011 | /* |
1012 | * Set up a list of consoles. Called from init/main.c |
1013 | */ |
1014 | static int __init console_setup(char *str) |
1015 | { |
1016 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
1017 | char *s, *options, *brl_options = NULL; |
1018 | int idx; |
1019 | |
1020 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1021 | if (!memcmp(str, "brl,", 4)) { |
1022 | brl_options = ""; |
1023 | str += 4; |
1024 | } else if (!memcmp(str, "brl=", 4)) { |
1025 | brl_options = str + 4; |
1026 | str = strchr(brl_options, ','); |
1027 | if (!str) { |
1028 | printk(KERN_ERR "need port name after brl=\n"); |
1029 | return 1; |
1030 | } |
1031 | *(str++) = 0; |
1032 | } |
1033 | #endif |
1034 | |
1035 | /* |
1036 | * Decode str into name, index, options. |
1037 | */ |
1038 | if (str[0] >= '0' && str[0] <= '9') { |
1039 | strcpy(buf, "ttyS"); |
1040 | strncpy(buf + 4, str, sizeof(buf) - 5); |
1041 | } else { |
1042 | strncpy(buf, str, sizeof(buf) - 1); |
1043 | } |
1044 | buf[sizeof(buf) - 1] = 0; |
1045 | if ((options = strchr(str, ',')) != NULL) |
1046 | *(options++) = 0; |
1047 | #ifdef __sparc__ |
1048 | if (!strcmp(str, "ttya")) |
1049 | strcpy(buf, "ttyS0"); |
1050 | if (!strcmp(str, "ttyb")) |
1051 | strcpy(buf, "ttyS1"); |
1052 | #endif |
1053 | for (s = buf; *s; s++) |
1054 | if ((*s >= '0' && *s <= '9') || *s == ',') |
1055 | break; |
1056 | idx = simple_strtoul(s, NULL, 10); |
1057 | *s = 0; |
1058 | |
1059 | __add_preferred_console(buf, idx, options, brl_options); |
1060 | console_set_on_cmdline = 1; |
1061 | return 1; |
1062 | } |
1063 | __setup("console=", console_setup); |
1064 | |
1065 | /** |
1066 | * add_preferred_console - add a device to the list of preferred consoles. |
1067 | * @name: device name |
1068 | * @idx: device index |
1069 | * @options: options for this console |
1070 | * |
1071 | * The last preferred console added will be used for kernel messages |
1072 | * and stdin/out/err for init. Normally this is used by console_setup |
1073 | * above to handle user-supplied console arguments; however it can also |
1074 | * be used by arch-specific code either to override the user or more |
1075 | * commonly to provide a default console (ie from PROM variables) when |
1076 | * the user has not supplied one. |
1077 | */ |
1078 | int add_preferred_console(char *name, int idx, char *options) |
1079 | { |
1080 | return __add_preferred_console(name, idx, options, NULL); |
1081 | } |
1082 | |
1083 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
1084 | { |
1085 | struct console_cmdline *c; |
1086 | int i; |
1087 | |
1088 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) |
1089 | if (strcmp(console_cmdline[i].name, name) == 0 && |
1090 | console_cmdline[i].index == idx) { |
1091 | c = &console_cmdline[i]; |
1092 | strlcpy(c->name, name_new, sizeof(c->name)); |
1093 | c->name[sizeof(c->name) - 1] = 0; |
1094 | c->options = options; |
1095 | c->index = idx_new; |
1096 | return i; |
1097 | } |
1098 | /* not found */ |
1099 | return -1; |
1100 | } |
1101 | |
1102 | int console_suspend_enabled = 1; |
1103 | EXPORT_SYMBOL(console_suspend_enabled); |
1104 | |
1105 | static int __init console_suspend_disable(char *str) |
1106 | { |
1107 | console_suspend_enabled = 0; |
1108 | return 1; |
1109 | } |
1110 | __setup("no_console_suspend", console_suspend_disable); |
1111 | |
1112 | /** |
1113 | * suspend_console - suspend the console subsystem |
1114 | * |
1115 | * This disables printk() while we go into suspend states |
1116 | */ |
1117 | void suspend_console(void) |
1118 | { |
1119 | if (!console_suspend_enabled) |
1120 | return; |
1121 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
1122 | console_lock(); |
1123 | console_suspended = 1; |
1124 | up(&console_sem); |
1125 | } |
1126 | |
1127 | void resume_console(void) |
1128 | { |
1129 | if (!console_suspend_enabled) |
1130 | return; |
1131 | down(&console_sem); |
1132 | console_suspended = 0; |
1133 | console_unlock(); |
1134 | } |
1135 | |
1136 | /** |
1137 | * console_cpu_notify - print deferred console messages after CPU hotplug |
1138 | * @self: notifier struct |
1139 | * @action: CPU hotplug event |
1140 | * @hcpu: unused |
1141 | * |
1142 | * If printk() is called from a CPU that is not online yet, the messages |
1143 | * will be spooled but will not show up on the console. This function is |
1144 | * called when a new CPU comes online (or fails to come up), and ensures |
1145 | * that any such output gets printed. |
1146 | */ |
1147 | static int __cpuinit console_cpu_notify(struct notifier_block *self, |
1148 | unsigned long action, void *hcpu) |
1149 | { |
1150 | switch (action) { |
1151 | case CPU_ONLINE: |
1152 | case CPU_DEAD: |
1153 | case CPU_DYING: |
1154 | case CPU_DOWN_FAILED: |
1155 | case CPU_UP_CANCELED: |
1156 | console_lock(); |
1157 | console_unlock(); |
1158 | } |
1159 | return NOTIFY_OK; |
1160 | } |
1161 | |
1162 | /** |
1163 | * console_lock - lock the console system for exclusive use. |
1164 | * |
1165 | * Acquires a lock which guarantees that the caller has |
1166 | * exclusive access to the console system and the console_drivers list. |
1167 | * |
1168 | * Can sleep, returns nothing. |
1169 | */ |
1170 | void console_lock(void) |
1171 | { |
1172 | BUG_ON(in_interrupt()); |
1173 | down(&console_sem); |
1174 | if (console_suspended) |
1175 | return; |
1176 | console_locked = 1; |
1177 | console_may_schedule = 1; |
1178 | } |
1179 | EXPORT_SYMBOL(console_lock); |
1180 | |
1181 | /** |
1182 | * console_trylock - try to lock the console system for exclusive use. |
1183 | * |
1184 | * Tried to acquire a lock which guarantees that the caller has |
1185 | * exclusive access to the console system and the console_drivers list. |
1186 | * |
1187 | * returns 1 on success, and 0 on failure to acquire the lock. |
1188 | */ |
1189 | int console_trylock(void) |
1190 | { |
1191 | if (down_trylock(&console_sem)) |
1192 | return 0; |
1193 | if (console_suspended) { |
1194 | up(&console_sem); |
1195 | return 0; |
1196 | } |
1197 | console_locked = 1; |
1198 | console_may_schedule = 0; |
1199 | return 1; |
1200 | } |
1201 | EXPORT_SYMBOL(console_trylock); |
1202 | |
1203 | int is_console_locked(void) |
1204 | { |
1205 | return console_locked; |
1206 | } |
1207 | |
1208 | static DEFINE_PER_CPU(int, printk_pending); |
1209 | |
1210 | void printk_tick(void) |
1211 | { |
1212 | if (__this_cpu_read(printk_pending)) { |
1213 | __this_cpu_write(printk_pending, 0); |
1214 | wake_up_interruptible(&log_wait); |
1215 | } |
1216 | } |
1217 | |
1218 | int printk_needs_cpu(int cpu) |
1219 | { |
1220 | if (cpu_is_offline(cpu)) |
1221 | printk_tick(); |
1222 | return __this_cpu_read(printk_pending); |
1223 | } |
1224 | |
1225 | void wake_up_klogd(void) |
1226 | { |
1227 | if (waitqueue_active(&log_wait)) |
1228 | this_cpu_write(printk_pending, 1); |
1229 | } |
1230 | |
1231 | /** |
1232 | * console_unlock - unlock the console system |
1233 | * |
1234 | * Releases the console_lock which the caller holds on the console system |
1235 | * and the console driver list. |
1236 | * |
1237 | * While the console_lock was held, console output may have been buffered |
1238 | * by printk(). If this is the case, console_unlock(); emits |
1239 | * the output prior to releasing the lock. |
1240 | * |
1241 | * If there is output waiting for klogd, we wake it up. |
1242 | * |
1243 | * console_unlock(); may be called from any context. |
1244 | */ |
1245 | void console_unlock(void) |
1246 | { |
1247 | unsigned long flags; |
1248 | unsigned _con_start, _log_end; |
1249 | unsigned wake_klogd = 0, retry = 0; |
1250 | |
1251 | if (console_suspended) { |
1252 | up(&console_sem); |
1253 | return; |
1254 | } |
1255 | |
1256 | console_may_schedule = 0; |
1257 | |
1258 | again: |
1259 | for ( ; ; ) { |
1260 | spin_lock_irqsave(&logbuf_lock, flags); |
1261 | wake_klogd |= log_start - log_end; |
1262 | if (con_start == log_end) |
1263 | break; /* Nothing to print */ |
1264 | _con_start = con_start; |
1265 | _log_end = log_end; |
1266 | con_start = log_end; /* Flush */ |
1267 | spin_unlock(&logbuf_lock); |
1268 | stop_critical_timings(); /* don't trace print latency */ |
1269 | call_console_drivers(_con_start, _log_end); |
1270 | start_critical_timings(); |
1271 | local_irq_restore(flags); |
1272 | } |
1273 | console_locked = 0; |
1274 | |
1275 | /* Release the exclusive_console once it is used */ |
1276 | if (unlikely(exclusive_console)) |
1277 | exclusive_console = NULL; |
1278 | |
1279 | spin_unlock(&logbuf_lock); |
1280 | |
1281 | up(&console_sem); |
1282 | |
1283 | /* |
1284 | * Someone could have filled up the buffer again, so re-check if there's |
1285 | * something to flush. In case we cannot trylock the console_sem again, |
1286 | * there's a new owner and the console_unlock() from them will do the |
1287 | * flush, no worries. |
1288 | */ |
1289 | spin_lock(&logbuf_lock); |
1290 | if (con_start != log_end) |
1291 | retry = 1; |
1292 | spin_unlock_irqrestore(&logbuf_lock, flags); |
1293 | if (retry && console_trylock()) |
1294 | goto again; |
1295 | |
1296 | if (wake_klogd) |
1297 | wake_up_klogd(); |
1298 | } |
1299 | EXPORT_SYMBOL(console_unlock); |
1300 | |
1301 | /** |
1302 | * console_conditional_schedule - yield the CPU if required |
1303 | * |
1304 | * If the console code is currently allowed to sleep, and |
1305 | * if this CPU should yield the CPU to another task, do |
1306 | * so here. |
1307 | * |
1308 | * Must be called within console_lock();. |
1309 | */ |
1310 | void __sched console_conditional_schedule(void) |
1311 | { |
1312 | if (console_may_schedule) |
1313 | cond_resched(); |
1314 | } |
1315 | EXPORT_SYMBOL(console_conditional_schedule); |
1316 | |
1317 | void console_unblank(void) |
1318 | { |
1319 | struct console *c; |
1320 | |
1321 | /* |
1322 | * console_unblank can no longer be called in interrupt context unless |
1323 | * oops_in_progress is set to 1.. |
1324 | */ |
1325 | if (oops_in_progress) { |
1326 | if (down_trylock(&console_sem) != 0) |
1327 | return; |
1328 | } else |
1329 | console_lock(); |
1330 | |
1331 | console_locked = 1; |
1332 | console_may_schedule = 0; |
1333 | for_each_console(c) |
1334 | if ((c->flags & CON_ENABLED) && c->unblank) |
1335 | c->unblank(); |
1336 | console_unlock(); |
1337 | } |
1338 | |
1339 | /* |
1340 | * Return the console tty driver structure and its associated index |
1341 | */ |
1342 | struct tty_driver *console_device(int *index) |
1343 | { |
1344 | struct console *c; |
1345 | struct tty_driver *driver = NULL; |
1346 | |
1347 | console_lock(); |
1348 | for_each_console(c) { |
1349 | if (!c->device) |
1350 | continue; |
1351 | driver = c->device(c, index); |
1352 | if (driver) |
1353 | break; |
1354 | } |
1355 | console_unlock(); |
1356 | return driver; |
1357 | } |
1358 | |
1359 | /* |
1360 | * Prevent further output on the passed console device so that (for example) |
1361 | * serial drivers can disable console output before suspending a port, and can |
1362 | * re-enable output afterwards. |
1363 | */ |
1364 | void console_stop(struct console *console) |
1365 | { |
1366 | console_lock(); |
1367 | console->flags &= ~CON_ENABLED; |
1368 | console_unlock(); |
1369 | } |
1370 | EXPORT_SYMBOL(console_stop); |
1371 | |
1372 | void console_start(struct console *console) |
1373 | { |
1374 | console_lock(); |
1375 | console->flags |= CON_ENABLED; |
1376 | console_unlock(); |
1377 | } |
1378 | EXPORT_SYMBOL(console_start); |
1379 | |
1380 | static int __read_mostly keep_bootcon; |
1381 | |
1382 | static int __init keep_bootcon_setup(char *str) |
1383 | { |
1384 | keep_bootcon = 1; |
1385 | printk(KERN_INFO "debug: skip boot console de-registration.\n"); |
1386 | |
1387 | return 0; |
1388 | } |
1389 | |
1390 | early_param("keep_bootcon", keep_bootcon_setup); |
1391 | |
1392 | /* |
1393 | * The console driver calls this routine during kernel initialization |
1394 | * to register the console printing procedure with printk() and to |
1395 | * print any messages that were printed by the kernel before the |
1396 | * console driver was initialized. |
1397 | * |
1398 | * This can happen pretty early during the boot process (because of |
1399 | * early_printk) - sometimes before setup_arch() completes - be careful |
1400 | * of what kernel features are used - they may not be initialised yet. |
1401 | * |
1402 | * There are two types of consoles - bootconsoles (early_printk) and |
1403 | * "real" consoles (everything which is not a bootconsole) which are |
1404 | * handled differently. |
1405 | * - Any number of bootconsoles can be registered at any time. |
1406 | * - As soon as a "real" console is registered, all bootconsoles |
1407 | * will be unregistered automatically. |
1408 | * - Once a "real" console is registered, any attempt to register a |
1409 | * bootconsoles will be rejected |
1410 | */ |
1411 | void register_console(struct console *newcon) |
1412 | { |
1413 | int i; |
1414 | unsigned long flags; |
1415 | struct console *bcon = NULL; |
1416 | |
1417 | /* |
1418 | * before we register a new CON_BOOT console, make sure we don't |
1419 | * already have a valid console |
1420 | */ |
1421 | if (console_drivers && newcon->flags & CON_BOOT) { |
1422 | /* find the last or real console */ |
1423 | for_each_console(bcon) { |
1424 | if (!(bcon->flags & CON_BOOT)) { |
1425 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", |
1426 | newcon->name, newcon->index); |
1427 | return; |
1428 | } |
1429 | } |
1430 | } |
1431 | |
1432 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1433 | bcon = console_drivers; |
1434 | |
1435 | if (preferred_console < 0 || bcon || !console_drivers) |
1436 | preferred_console = selected_console; |
1437 | |
1438 | if (newcon->early_setup) |
1439 | newcon->early_setup(); |
1440 | |
1441 | /* |
1442 | * See if we want to use this console driver. If we |
1443 | * didn't select a console we take the first one |
1444 | * that registers here. |
1445 | */ |
1446 | if (preferred_console < 0) { |
1447 | if (newcon->index < 0) |
1448 | newcon->index = 0; |
1449 | if (newcon->setup == NULL || |
1450 | newcon->setup(newcon, NULL) == 0) { |
1451 | newcon->flags |= CON_ENABLED; |
1452 | if (newcon->device) { |
1453 | newcon->flags |= CON_CONSDEV; |
1454 | preferred_console = 0; |
1455 | } |
1456 | } |
1457 | } |
1458 | |
1459 | /* |
1460 | * See if this console matches one we selected on |
1461 | * the command line. |
1462 | */ |
1463 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1464 | i++) { |
1465 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1466 | continue; |
1467 | if (newcon->index >= 0 && |
1468 | newcon->index != console_cmdline[i].index) |
1469 | continue; |
1470 | if (newcon->index < 0) |
1471 | newcon->index = console_cmdline[i].index; |
1472 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1473 | if (console_cmdline[i].brl_options) { |
1474 | newcon->flags |= CON_BRL; |
1475 | braille_register_console(newcon, |
1476 | console_cmdline[i].index, |
1477 | console_cmdline[i].options, |
1478 | console_cmdline[i].brl_options); |
1479 | return; |
1480 | } |
1481 | #endif |
1482 | if (newcon->setup && |
1483 | newcon->setup(newcon, console_cmdline[i].options) != 0) |
1484 | break; |
1485 | newcon->flags |= CON_ENABLED; |
1486 | newcon->index = console_cmdline[i].index; |
1487 | if (i == selected_console) { |
1488 | newcon->flags |= CON_CONSDEV; |
1489 | preferred_console = selected_console; |
1490 | } |
1491 | break; |
1492 | } |
1493 | |
1494 | if (!(newcon->flags & CON_ENABLED)) |
1495 | return; |
1496 | |
1497 | /* |
1498 | * If we have a bootconsole, and are switching to a real console, |
1499 | * don't print everything out again, since when the boot console, and |
1500 | * the real console are the same physical device, it's annoying to |
1501 | * see the beginning boot messages twice |
1502 | */ |
1503 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) |
1504 | newcon->flags &= ~CON_PRINTBUFFER; |
1505 | |
1506 | /* |
1507 | * Put this console in the list - keep the |
1508 | * preferred driver at the head of the list. |
1509 | */ |
1510 | console_lock(); |
1511 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1512 | newcon->next = console_drivers; |
1513 | console_drivers = newcon; |
1514 | if (newcon->next) |
1515 | newcon->next->flags &= ~CON_CONSDEV; |
1516 | } else { |
1517 | newcon->next = console_drivers->next; |
1518 | console_drivers->next = newcon; |
1519 | } |
1520 | if (newcon->flags & CON_PRINTBUFFER) { |
1521 | /* |
1522 | * console_unlock(); will print out the buffered messages |
1523 | * for us. |
1524 | */ |
1525 | spin_lock_irqsave(&logbuf_lock, flags); |
1526 | con_start = log_start; |
1527 | spin_unlock_irqrestore(&logbuf_lock, flags); |
1528 | /* |
1529 | * We're about to replay the log buffer. Only do this to the |
1530 | * just-registered console to avoid excessive message spam to |
1531 | * the already-registered consoles. |
1532 | */ |
1533 | exclusive_console = newcon; |
1534 | } |
1535 | console_unlock(); |
1536 | console_sysfs_notify(); |
1537 | |
1538 | /* |
1539 | * By unregistering the bootconsoles after we enable the real console |
1540 | * we get the "console xxx enabled" message on all the consoles - |
1541 | * boot consoles, real consoles, etc - this is to ensure that end |
1542 | * users know there might be something in the kernel's log buffer that |
1543 | * went to the bootconsole (that they do not see on the real console) |
1544 | */ |
1545 | if (bcon && |
1546 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && |
1547 | !keep_bootcon) { |
1548 | /* we need to iterate through twice, to make sure we print |
1549 | * everything out, before we unregister the console(s) |
1550 | */ |
1551 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", |
1552 | newcon->name, newcon->index); |
1553 | for_each_console(bcon) |
1554 | if (bcon->flags & CON_BOOT) |
1555 | unregister_console(bcon); |
1556 | } else { |
1557 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", |
1558 | (newcon->flags & CON_BOOT) ? "boot" : "" , |
1559 | newcon->name, newcon->index); |
1560 | } |
1561 | } |
1562 | EXPORT_SYMBOL(register_console); |
1563 | |
1564 | int unregister_console(struct console *console) |
1565 | { |
1566 | struct console *a, *b; |
1567 | int res = 1; |
1568 | |
1569 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1570 | if (console->flags & CON_BRL) |
1571 | return braille_unregister_console(console); |
1572 | #endif |
1573 | |
1574 | console_lock(); |
1575 | if (console_drivers == console) { |
1576 | console_drivers=console->next; |
1577 | res = 0; |
1578 | } else if (console_drivers) { |
1579 | for (a=console_drivers->next, b=console_drivers ; |
1580 | a; b=a, a=b->next) { |
1581 | if (a == console) { |
1582 | b->next = a->next; |
1583 | res = 0; |
1584 | break; |
1585 | } |
1586 | } |
1587 | } |
1588 | |
1589 | /* |
1590 | * If this isn't the last console and it has CON_CONSDEV set, we |
1591 | * need to set it on the next preferred console. |
1592 | */ |
1593 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
1594 | console_drivers->flags |= CON_CONSDEV; |
1595 | |
1596 | console_unlock(); |
1597 | console_sysfs_notify(); |
1598 | return res; |
1599 | } |
1600 | EXPORT_SYMBOL(unregister_console); |
1601 | |
1602 | static int __init printk_late_init(void) |
1603 | { |
1604 | struct console *con; |
1605 | |
1606 | for_each_console(con) { |
1607 | if (!keep_bootcon && con->flags & CON_BOOT) { |
1608 | printk(KERN_INFO "turn off boot console %s%d\n", |
1609 | con->name, con->index); |
1610 | unregister_console(con); |
1611 | } |
1612 | } |
1613 | hotcpu_notifier(console_cpu_notify, 0); |
1614 | return 0; |
1615 | } |
1616 | late_initcall(printk_late_init); |
1617 | |
1618 | #if defined CONFIG_PRINTK |
1619 | |
1620 | /* |
1621 | * printk rate limiting, lifted from the networking subsystem. |
1622 | * |
1623 | * This enforces a rate limit: not more than 10 kernel messages |
1624 | * every 5s to make a denial-of-service attack impossible. |
1625 | */ |
1626 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1627 | |
1628 | int __printk_ratelimit(const char *func) |
1629 | { |
1630 | return ___ratelimit(&printk_ratelimit_state, func); |
1631 | } |
1632 | EXPORT_SYMBOL(__printk_ratelimit); |
1633 | |
1634 | /** |
1635 | * printk_timed_ratelimit - caller-controlled printk ratelimiting |
1636 | * @caller_jiffies: pointer to caller's state |
1637 | * @interval_msecs: minimum interval between prints |
1638 | * |
1639 | * printk_timed_ratelimit() returns true if more than @interval_msecs |
1640 | * milliseconds have elapsed since the last time printk_timed_ratelimit() |
1641 | * returned true. |
1642 | */ |
1643 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, |
1644 | unsigned int interval_msecs) |
1645 | { |
1646 | if (*caller_jiffies == 0 |
1647 | || !time_in_range(jiffies, *caller_jiffies, |
1648 | *caller_jiffies |
1649 | + msecs_to_jiffies(interval_msecs))) { |
1650 | *caller_jiffies = jiffies; |
1651 | return true; |
1652 | } |
1653 | return false; |
1654 | } |
1655 | EXPORT_SYMBOL(printk_timed_ratelimit); |
1656 | |
1657 | static DEFINE_SPINLOCK(dump_list_lock); |
1658 | static LIST_HEAD(dump_list); |
1659 | |
1660 | /** |
1661 | * kmsg_dump_register - register a kernel log dumper. |
1662 | * @dumper: pointer to the kmsg_dumper structure |
1663 | * |
1664 | * Adds a kernel log dumper to the system. The dump callback in the |
1665 | * structure will be called when the kernel oopses or panics and must be |
1666 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. |
1667 | */ |
1668 | int kmsg_dump_register(struct kmsg_dumper *dumper) |
1669 | { |
1670 | unsigned long flags; |
1671 | int err = -EBUSY; |
1672 | |
1673 | /* The dump callback needs to be set */ |
1674 | if (!dumper->dump) |
1675 | return -EINVAL; |
1676 | |
1677 | spin_lock_irqsave(&dump_list_lock, flags); |
1678 | /* Don't allow registering multiple times */ |
1679 | if (!dumper->registered) { |
1680 | dumper->registered = 1; |
1681 | list_add_tail_rcu(&dumper->list, &dump_list); |
1682 | err = 0; |
1683 | } |
1684 | spin_unlock_irqrestore(&dump_list_lock, flags); |
1685 | |
1686 | return err; |
1687 | } |
1688 | EXPORT_SYMBOL_GPL(kmsg_dump_register); |
1689 | |
1690 | /** |
1691 | * kmsg_dump_unregister - unregister a kmsg dumper. |
1692 | * @dumper: pointer to the kmsg_dumper structure |
1693 | * |
1694 | * Removes a dump device from the system. Returns zero on success and |
1695 | * %-EINVAL otherwise. |
1696 | */ |
1697 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) |
1698 | { |
1699 | unsigned long flags; |
1700 | int err = -EINVAL; |
1701 | |
1702 | spin_lock_irqsave(&dump_list_lock, flags); |
1703 | if (dumper->registered) { |
1704 | dumper->registered = 0; |
1705 | list_del_rcu(&dumper->list); |
1706 | err = 0; |
1707 | } |
1708 | spin_unlock_irqrestore(&dump_list_lock, flags); |
1709 | synchronize_rcu(); |
1710 | |
1711 | return err; |
1712 | } |
1713 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); |
1714 | |
1715 | /** |
1716 | * kmsg_dump - dump kernel log to kernel message dumpers. |
1717 | * @reason: the reason (oops, panic etc) for dumping |
1718 | * |
1719 | * Iterate through each of the dump devices and call the oops/panic |
1720 | * callbacks with the log buffer. |
1721 | */ |
1722 | void kmsg_dump(enum kmsg_dump_reason reason) |
1723 | { |
1724 | unsigned long end; |
1725 | unsigned chars; |
1726 | struct kmsg_dumper *dumper; |
1727 | const char *s1, *s2; |
1728 | unsigned long l1, l2; |
1729 | unsigned long flags; |
1730 | |
1731 | /* Theoretically, the log could move on after we do this, but |
1732 | there's not a lot we can do about that. The new messages |
1733 | will overwrite the start of what we dump. */ |
1734 | spin_lock_irqsave(&logbuf_lock, flags); |
1735 | end = log_end & LOG_BUF_MASK; |
1736 | chars = logged_chars; |
1737 | spin_unlock_irqrestore(&logbuf_lock, flags); |
1738 | |
1739 | if (chars > end) { |
1740 | s1 = log_buf + log_buf_len - chars + end; |
1741 | l1 = chars - end; |
1742 | |
1743 | s2 = log_buf; |
1744 | l2 = end; |
1745 | } else { |
1746 | s1 = ""; |
1747 | l1 = 0; |
1748 | |
1749 | s2 = log_buf + end - chars; |
1750 | l2 = chars; |
1751 | } |
1752 | |
1753 | rcu_read_lock(); |
1754 | list_for_each_entry_rcu(dumper, &dump_list, list) |
1755 | dumper->dump(dumper, reason, s1, l1, s2, l2); |
1756 | rcu_read_unlock(); |
1757 | } |
1758 | #endif |
1759 |
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v2.6.34-rc5
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