Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/kernel/printk.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * Modified to make sys_syslog() more flexible: added commands to | |
7 | * return the last 4k of kernel messages, regardless of whether | |
8 | * they've been read or not. Added option to suppress kernel printk's | |
9 | * to the console. Added hook for sending the console messages | |
10 | * elsewhere, in preparation for a serial line console (someday). | |
11 | * Ted Ts'o, 2/11/93. | |
12 | * Modified for sysctl support, 1/8/97, Chris Horn. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 | 15 | * Rewrote bits to get rid of console_lock |
e1f8e874 | 16 | * 01Mar01 Andrew Morton |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
1da177e4 LT |
23 | #include <linux/console.h> |
24 | #include <linux/init.h> | |
bfe8df3d RD |
25 | #include <linux/jiffies.h> |
26 | #include <linux/nmi.h> | |
1da177e4 | 27 | #include <linux/module.h> |
3b9c0410 | 28 | #include <linux/moduleparam.h> |
1da177e4 | 29 | #include <linux/interrupt.h> /* For in_interrupt() */ |
1da177e4 LT |
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> | |
04d491ab | 35 | #include <linux/kexec.h> |
1da177e4 LT |
36 | |
37 | #include <asm/uaccess.h> | |
38 | ||
4d091611 RG |
39 | /* |
40 | * for_each_console() allows you to iterate on each console | |
41 | */ | |
42 | #define for_each_console(con) \ | |
43 | for (con = console_drivers; con != NULL; con = con->next) | |
44 | ||
076f9776 IM |
45 | /* |
46 | * Architectures can override it: | |
47 | */ | |
e17ba73b | 48 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
076f9776 IM |
49 | { |
50 | } | |
51 | ||
1da177e4 LT |
52 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
53 | ||
54 | /* printk's without a loglevel use this.. */ | |
55 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ | |
56 | ||
57 | /* We show everything that is MORE important than this.. */ | |
58 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
59 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
60 | ||
61 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
62 | ||
63 | int console_printk[4] = { | |
64 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
65 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
66 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
67 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
68 | }; | |
69 | ||
1da177e4 | 70 | /* |
0bbfb7c2 | 71 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
72 | * their unblank() callback or not. So let's export it. |
73 | */ | |
74 | int oops_in_progress; | |
75 | EXPORT_SYMBOL(oops_in_progress); | |
76 | ||
77 | /* | |
78 | * console_sem protects the console_drivers list, and also | |
79 | * provides serialisation for access to the entire console | |
80 | * driver system. | |
81 | */ | |
82 | static DECLARE_MUTEX(console_sem); | |
83 | struct console *console_drivers; | |
a29d1cfe IM |
84 | EXPORT_SYMBOL_GPL(console_drivers); |
85 | ||
1da177e4 LT |
86 | /* |
87 | * This is used for debugging the mess that is the VT code by | |
88 | * keeping track if we have the console semaphore held. It's | |
89 | * definitely not the perfect debug tool (we don't know if _WE_ | |
90 | * hold it are racing, but it helps tracking those weird code | |
91 | * path in the console code where we end up in places I want | |
92 | * locked without the console sempahore held | |
93 | */ | |
557240b4 | 94 | static int console_locked, console_suspended; |
1da177e4 LT |
95 | |
96 | /* | |
97 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
98 | * It is also used in interesting ways to provide interlocking in | |
99 | * release_console_sem(). | |
100 | */ | |
101 | static DEFINE_SPINLOCK(logbuf_lock); | |
102 | ||
eed4a2ab | 103 | #define LOG_BUF_MASK (log_buf_len-1) |
1da177e4 LT |
104 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
105 | ||
106 | /* | |
107 | * The indices into log_buf are not constrained to log_buf_len - they | |
108 | * must be masked before subscripting | |
109 | */ | |
eed4a2ab DV |
110 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
111 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ | |
112 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
113 | |
114 | /* | |
115 | * Array of consoles built from command line options (console=) | |
116 | */ | |
117 | struct console_cmdline | |
118 | { | |
119 | char name[8]; /* Name of the driver */ | |
120 | int index; /* Minor dev. to use */ | |
121 | char *options; /* Options for the driver */ | |
f7511d5f ST |
122 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
123 | char *brl_options; /* Options for braille driver */ | |
124 | #endif | |
1da177e4 LT |
125 | }; |
126 | ||
127 | #define MAX_CMDLINECONSOLES 8 | |
128 | ||
129 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
130 | static int selected_console = -1; | |
131 | static int preferred_console = -1; | |
9e124fe1 MA |
132 | int console_set_on_cmdline; |
133 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
134 | |
135 | /* Flag: console code may call schedule() */ | |
136 | static int console_may_schedule; | |
137 | ||
d59745ce MM |
138 | #ifdef CONFIG_PRINTK |
139 | ||
140 | static char __log_buf[__LOG_BUF_LEN]; | |
141 | static char *log_buf = __log_buf; | |
142 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 143 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
d59745ce | 144 | |
04d491ab NH |
145 | #ifdef CONFIG_KEXEC |
146 | /* | |
147 | * This appends the listed symbols to /proc/vmcoreinfo | |
148 | * | |
149 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
150 | * obtain access to symbols that are otherwise very difficult to locate. These | |
151 | * symbols are specifically used so that utilities can access and extract the | |
152 | * dmesg log from a vmcore file after a crash. | |
153 | */ | |
154 | void log_buf_kexec_setup(void) | |
155 | { | |
156 | VMCOREINFO_SYMBOL(log_buf); | |
157 | VMCOREINFO_SYMBOL(log_end); | |
158 | VMCOREINFO_SYMBOL(log_buf_len); | |
159 | VMCOREINFO_SYMBOL(logged_chars); | |
160 | } | |
161 | #endif | |
162 | ||
1da177e4 LT |
163 | static int __init log_buf_len_setup(char *str) |
164 | { | |
eed4a2ab | 165 | unsigned size = memparse(str, &str); |
1da177e4 LT |
166 | unsigned long flags; |
167 | ||
168 | if (size) | |
169 | size = roundup_pow_of_two(size); | |
170 | if (size > log_buf_len) { | |
eed4a2ab | 171 | unsigned start, dest_idx, offset; |
40dc5651 | 172 | char *new_log_buf; |
1da177e4 LT |
173 | |
174 | new_log_buf = alloc_bootmem(size); | |
175 | if (!new_log_buf) { | |
40dc5651 | 176 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
177 | goto out; |
178 | } | |
179 | ||
180 | spin_lock_irqsave(&logbuf_lock, flags); | |
181 | log_buf_len = size; | |
182 | log_buf = new_log_buf; | |
183 | ||
184 | offset = start = min(con_start, log_start); | |
185 | dest_idx = 0; | |
186 | while (start != log_end) { | |
187 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
188 | start++; | |
189 | dest_idx++; | |
190 | } | |
191 | log_start -= offset; | |
192 | con_start -= offset; | |
193 | log_end -= offset; | |
194 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
195 | ||
40dc5651 | 196 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
197 | } |
198 | out: | |
1da177e4 LT |
199 | return 1; |
200 | } | |
201 | ||
202 | __setup("log_buf_len=", log_buf_len_setup); | |
203 | ||
bfe8df3d RD |
204 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
205 | ||
206 | static unsigned int boot_delay; /* msecs delay after each printk during bootup */ | |
207 | static unsigned long long printk_delay_msec; /* per msec, based on boot_delay */ | |
208 | ||
209 | static int __init boot_delay_setup(char *str) | |
210 | { | |
211 | unsigned long lpj; | |
212 | unsigned long long loops_per_msec; | |
213 | ||
214 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
215 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
216 | ||
217 | get_option(&str, &boot_delay); | |
218 | if (boot_delay > 10 * 1000) | |
219 | boot_delay = 0; | |
220 | ||
221 | printk_delay_msec = loops_per_msec; | |
222 | printk(KERN_DEBUG "boot_delay: %u, preset_lpj: %ld, lpj: %lu, " | |
223 | "HZ: %d, printk_delay_msec: %llu\n", | |
224 | boot_delay, preset_lpj, lpj, HZ, printk_delay_msec); | |
225 | return 1; | |
226 | } | |
227 | __setup("boot_delay=", boot_delay_setup); | |
228 | ||
229 | static void boot_delay_msec(void) | |
230 | { | |
231 | unsigned long long k; | |
232 | unsigned long timeout; | |
233 | ||
234 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
235 | return; | |
236 | ||
237 | k = (unsigned long long)printk_delay_msec * boot_delay; | |
238 | ||
239 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
240 | while (k) { | |
241 | k--; | |
242 | cpu_relax(); | |
243 | /* | |
244 | * use (volatile) jiffies to prevent | |
245 | * compiler reduction; loop termination via jiffies | |
246 | * is secondary and may or may not happen. | |
247 | */ | |
248 | if (time_after(jiffies, timeout)) | |
249 | break; | |
250 | touch_nmi_watchdog(); | |
251 | } | |
252 | } | |
253 | #else | |
254 | static inline void boot_delay_msec(void) | |
255 | { | |
256 | } | |
257 | #endif | |
258 | ||
1da177e4 LT |
259 | /* |
260 | * Commands to do_syslog: | |
261 | * | |
262 | * 0 -- Close the log. Currently a NOP. | |
263 | * 1 -- Open the log. Currently a NOP. | |
264 | * 2 -- Read from the log. | |
265 | * 3 -- Read all messages remaining in the ring buffer. | |
266 | * 4 -- Read and clear all messages remaining in the ring buffer | |
267 | * 5 -- Clear ring buffer. | |
268 | * 6 -- Disable printk's to console | |
269 | * 7 -- Enable printk's to console | |
270 | * 8 -- Set level of messages printed to console | |
271 | * 9 -- Return number of unread characters in the log buffer | |
272 | * 10 -- Return size of the log buffer | |
273 | */ | |
40dc5651 | 274 | int do_syslog(int type, char __user *buf, int len) |
1da177e4 | 275 | { |
eed4a2ab | 276 | unsigned i, j, limit, count; |
1da177e4 LT |
277 | int do_clear = 0; |
278 | char c; | |
279 | int error = 0; | |
280 | ||
281 | error = security_syslog(type); | |
282 | if (error) | |
283 | return error; | |
284 | ||
285 | switch (type) { | |
286 | case 0: /* Close log */ | |
287 | break; | |
288 | case 1: /* Open log */ | |
289 | break; | |
290 | case 2: /* Read from log */ | |
291 | error = -EINVAL; | |
292 | if (!buf || len < 0) | |
293 | goto out; | |
294 | error = 0; | |
295 | if (!len) | |
296 | goto out; | |
297 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
298 | error = -EFAULT; | |
299 | goto out; | |
300 | } | |
40dc5651 JJ |
301 | error = wait_event_interruptible(log_wait, |
302 | (log_start - log_end)); | |
1da177e4 LT |
303 | if (error) |
304 | goto out; | |
305 | i = 0; | |
306 | spin_lock_irq(&logbuf_lock); | |
307 | while (!error && (log_start != log_end) && i < len) { | |
308 | c = LOG_BUF(log_start); | |
309 | log_start++; | |
310 | spin_unlock_irq(&logbuf_lock); | |
311 | error = __put_user(c,buf); | |
312 | buf++; | |
313 | i++; | |
314 | cond_resched(); | |
315 | spin_lock_irq(&logbuf_lock); | |
316 | } | |
317 | spin_unlock_irq(&logbuf_lock); | |
318 | if (!error) | |
319 | error = i; | |
320 | break; | |
321 | case 4: /* Read/clear last kernel messages */ | |
40dc5651 | 322 | do_clear = 1; |
1da177e4 LT |
323 | /* FALL THRU */ |
324 | case 3: /* Read last kernel messages */ | |
325 | error = -EINVAL; | |
326 | if (!buf || len < 0) | |
327 | goto out; | |
328 | error = 0; | |
329 | if (!len) | |
330 | goto out; | |
331 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
332 | error = -EFAULT; | |
333 | goto out; | |
334 | } | |
335 | count = len; | |
336 | if (count > log_buf_len) | |
337 | count = log_buf_len; | |
338 | spin_lock_irq(&logbuf_lock); | |
339 | if (count > logged_chars) | |
340 | count = logged_chars; | |
341 | if (do_clear) | |
342 | logged_chars = 0; | |
343 | limit = log_end; | |
344 | /* | |
345 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 346 | * printk() could overwrite the messages |
1da177e4 LT |
347 | * we try to copy to user space. Therefore |
348 | * the messages are copied in reverse. <manfreds> | |
349 | */ | |
40dc5651 | 350 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
351 | j = limit-1-i; |
352 | if (j + log_buf_len < log_end) | |
353 | break; | |
354 | c = LOG_BUF(j); | |
355 | spin_unlock_irq(&logbuf_lock); | |
356 | error = __put_user(c,&buf[count-1-i]); | |
357 | cond_resched(); | |
358 | spin_lock_irq(&logbuf_lock); | |
359 | } | |
360 | spin_unlock_irq(&logbuf_lock); | |
361 | if (error) | |
362 | break; | |
363 | error = i; | |
40dc5651 | 364 | if (i != count) { |
1da177e4 LT |
365 | int offset = count-error; |
366 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 367 | for (i = 0; i < error; i++) { |
1da177e4 LT |
368 | if (__get_user(c,&buf[i+offset]) || |
369 | __put_user(c,&buf[i])) { | |
370 | error = -EFAULT; | |
371 | break; | |
372 | } | |
373 | cond_resched(); | |
374 | } | |
375 | } | |
376 | break; | |
377 | case 5: /* Clear ring buffer */ | |
378 | logged_chars = 0; | |
379 | break; | |
380 | case 6: /* Disable logging to console */ | |
381 | console_loglevel = minimum_console_loglevel; | |
382 | break; | |
383 | case 7: /* Enable logging to console */ | |
384 | console_loglevel = default_console_loglevel; | |
385 | break; | |
386 | case 8: /* Set level of messages printed to console */ | |
387 | error = -EINVAL; | |
388 | if (len < 1 || len > 8) | |
389 | goto out; | |
390 | if (len < minimum_console_loglevel) | |
391 | len = minimum_console_loglevel; | |
392 | console_loglevel = len; | |
393 | error = 0; | |
394 | break; | |
395 | case 9: /* Number of chars in the log buffer */ | |
396 | error = log_end - log_start; | |
397 | break; | |
398 | case 10: /* Size of the log buffer */ | |
399 | error = log_buf_len; | |
400 | break; | |
401 | default: | |
402 | error = -EINVAL; | |
403 | break; | |
404 | } | |
405 | out: | |
406 | return error; | |
407 | } | |
408 | ||
1e7bfb21 | 409 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 LT |
410 | { |
411 | return do_syslog(type, buf, len); | |
412 | } | |
413 | ||
414 | /* | |
415 | * Call the console drivers on a range of log_buf | |
416 | */ | |
eed4a2ab | 417 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
418 | { |
419 | struct console *con; | |
420 | ||
4d091611 | 421 | for_each_console(con) { |
76a8ad29 ME |
422 | if ((con->flags & CON_ENABLED) && con->write && |
423 | (cpu_online(smp_processor_id()) || | |
424 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
425 | con->write(con, &LOG_BUF(start), end - start); |
426 | } | |
427 | } | |
428 | ||
79290822 IM |
429 | static int __read_mostly ignore_loglevel; |
430 | ||
99eea6a1 | 431 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
432 | { |
433 | ignore_loglevel = 1; | |
434 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
435 | ||
c4772d99 | 436 | return 0; |
79290822 IM |
437 | } |
438 | ||
c4772d99 | 439 | early_param("ignore_loglevel", ignore_loglevel_setup); |
79290822 | 440 | |
1da177e4 LT |
441 | /* |
442 | * Write out chars from start to end - 1 inclusive | |
443 | */ | |
eed4a2ab DV |
444 | static void _call_console_drivers(unsigned start, |
445 | unsigned end, int msg_log_level) | |
1da177e4 | 446 | { |
79290822 | 447 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
448 | console_drivers && start != end) { |
449 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
450 | /* wrapped write */ | |
451 | __call_console_drivers(start & LOG_BUF_MASK, | |
452 | log_buf_len); | |
453 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
454 | } else { | |
455 | __call_console_drivers(start, end); | |
456 | } | |
457 | } | |
458 | } | |
459 | ||
460 | /* | |
461 | * Call the console drivers, asking them to write out | |
462 | * log_buf[start] to log_buf[end - 1]. | |
463 | * The console_sem must be held. | |
464 | */ | |
eed4a2ab | 465 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 466 | { |
eed4a2ab | 467 | unsigned cur_index, start_print; |
1da177e4 LT |
468 | static int msg_level = -1; |
469 | ||
eed4a2ab | 470 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
471 | |
472 | cur_index = start; | |
473 | start_print = start; | |
474 | while (cur_index != end) { | |
40dc5651 JJ |
475 | if (msg_level < 0 && ((end - cur_index) > 2) && |
476 | LOG_BUF(cur_index + 0) == '<' && | |
477 | LOG_BUF(cur_index + 1) >= '0' && | |
478 | LOG_BUF(cur_index + 1) <= '7' && | |
479 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
480 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
481 | cur_index += 3; | |
482 | start_print = cur_index; | |
483 | } | |
484 | while (cur_index != end) { | |
485 | char c = LOG_BUF(cur_index); | |
1da177e4 | 486 | |
40dc5651 | 487 | cur_index++; |
1da177e4 LT |
488 | if (c == '\n') { |
489 | if (msg_level < 0) { | |
490 | /* | |
491 | * printk() has already given us loglevel tags in | |
492 | * the buffer. This code is here in case the | |
493 | * log buffer has wrapped right round and scribbled | |
494 | * on those tags | |
495 | */ | |
496 | msg_level = default_message_loglevel; | |
497 | } | |
498 | _call_console_drivers(start_print, cur_index, msg_level); | |
499 | msg_level = -1; | |
500 | start_print = cur_index; | |
501 | break; | |
502 | } | |
503 | } | |
504 | } | |
505 | _call_console_drivers(start_print, end, msg_level); | |
506 | } | |
507 | ||
508 | static void emit_log_char(char c) | |
509 | { | |
510 | LOG_BUF(log_end) = c; | |
511 | log_end++; | |
512 | if (log_end - log_start > log_buf_len) | |
513 | log_start = log_end - log_buf_len; | |
514 | if (log_end - con_start > log_buf_len) | |
515 | con_start = log_end - log_buf_len; | |
516 | if (logged_chars < log_buf_len) | |
517 | logged_chars++; | |
518 | } | |
519 | ||
520 | /* | |
521 | * Zap console related locks when oopsing. Only zap at most once | |
522 | * every 10 seconds, to leave time for slow consoles to print a | |
523 | * full oops. | |
524 | */ | |
525 | static void zap_locks(void) | |
526 | { | |
527 | static unsigned long oops_timestamp; | |
528 | ||
529 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 530 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
531 | return; |
532 | ||
533 | oops_timestamp = jiffies; | |
534 | ||
535 | /* If a crash is occurring, make sure we can't deadlock */ | |
536 | spin_lock_init(&logbuf_lock); | |
537 | /* And make sure that we print immediately */ | |
538 | init_MUTEX(&console_sem); | |
539 | } | |
540 | ||
541 | #if defined(CONFIG_PRINTK_TIME) | |
542 | static int printk_time = 1; | |
543 | #else | |
544 | static int printk_time = 0; | |
545 | #endif | |
e84845c4 | 546 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 547 | |
76a8ad29 ME |
548 | /* Check if we have any console registered that can be called early in boot. */ |
549 | static int have_callable_console(void) | |
550 | { | |
551 | struct console *con; | |
552 | ||
4d091611 | 553 | for_each_console(con) |
76a8ad29 ME |
554 | if (con->flags & CON_ANYTIME) |
555 | return 1; | |
556 | ||
557 | return 0; | |
558 | } | |
559 | ||
ddad86c2 MW |
560 | /** |
561 | * printk - print a kernel message | |
562 | * @fmt: format string | |
563 | * | |
72fd4a35 | 564 | * This is printk(). It can be called from any context. We want it to work. |
40dc5651 | 565 | * |
1da177e4 LT |
566 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
567 | * call the console drivers. If we fail to get the semaphore we place the output | |
568 | * into the log buffer and return. The current holder of the console_sem will | |
569 | * notice the new output in release_console_sem() and will send it to the | |
570 | * consoles before releasing the semaphore. | |
571 | * | |
572 | * One effect of this deferred printing is that code which calls printk() and | |
573 | * then changes console_loglevel may break. This is because console_loglevel | |
574 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
575 | * |
576 | * See also: | |
577 | * printf(3) | |
20036fdc AK |
578 | * |
579 | * See the vsnprintf() documentation for format string extensions over C99. | |
1da177e4 | 580 | */ |
d59745ce | 581 | |
1da177e4 LT |
582 | asmlinkage int printk(const char *fmt, ...) |
583 | { | |
584 | va_list args; | |
585 | int r; | |
586 | ||
587 | va_start(args, fmt); | |
588 | r = vprintk(fmt, args); | |
589 | va_end(args); | |
590 | ||
591 | return r; | |
592 | } | |
593 | ||
fe21773d DH |
594 | /* cpu currently holding logbuf_lock */ |
595 | static volatile unsigned int printk_cpu = UINT_MAX; | |
596 | ||
266c2e0a LT |
597 | /* |
598 | * Can we actually use the console at this time on this cpu? | |
599 | * | |
600 | * Console drivers may assume that per-cpu resources have | |
601 | * been allocated. So unless they're explicitly marked as | |
602 | * being able to cope (CON_ANYTIME) don't call them until | |
603 | * this CPU is officially up. | |
604 | */ | |
605 | static inline int can_use_console(unsigned int cpu) | |
606 | { | |
607 | return cpu_online(cpu) || have_callable_console(); | |
608 | } | |
609 | ||
610 | /* | |
611 | * Try to get console ownership to actually show the kernel | |
612 | * messages from a 'printk'. Return true (and with the | |
613 | * console_semaphore held, and 'console_locked' set) if it | |
614 | * is successful, false otherwise. | |
615 | * | |
616 | * This gets called with the 'logbuf_lock' spinlock held and | |
617 | * interrupts disabled. It should return with 'lockbuf_lock' | |
618 | * released but interrupts still disabled. | |
619 | */ | |
620 | static int acquire_console_semaphore_for_printk(unsigned int cpu) | |
621 | { | |
622 | int retval = 0; | |
623 | ||
093a07e2 LT |
624 | if (!try_acquire_console_sem()) { |
625 | retval = 1; | |
626 | ||
627 | /* | |
628 | * If we can't use the console, we need to release | |
629 | * the console semaphore by hand to avoid flushing | |
630 | * the buffer. We need to hold the console semaphore | |
631 | * in order to do this test safely. | |
632 | */ | |
633 | if (!can_use_console(cpu)) { | |
634 | console_locked = 0; | |
635 | up(&console_sem); | |
636 | retval = 0; | |
637 | } | |
638 | } | |
266c2e0a LT |
639 | printk_cpu = UINT_MAX; |
640 | spin_unlock(&logbuf_lock); | |
641 | return retval; | |
642 | } | |
3b8945e8 TH |
643 | static const char recursion_bug_msg [] = |
644 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
645 | static int recursion_bug; | |
edb123e1 | 646 | static int new_text_line = 1; |
3b8945e8 | 647 | static char printk_buf[1024]; |
32a76006 | 648 | |
1da177e4 LT |
649 | asmlinkage int vprintk(const char *fmt, va_list args) |
650 | { | |
32a76006 | 651 | int printed_len = 0; |
09159308 | 652 | int current_log_level = default_message_loglevel; |
ac60ad74 | 653 | unsigned long flags; |
32a76006 | 654 | int this_cpu; |
1da177e4 | 655 | char *p; |
1da177e4 | 656 | |
bfe8df3d RD |
657 | boot_delay_msec(); |
658 | ||
fe21773d | 659 | preempt_disable(); |
1da177e4 | 660 | /* This stops the holder of console_sem just where we want him */ |
1efc5da3 | 661 | raw_local_irq_save(flags); |
32a76006 IM |
662 | this_cpu = smp_processor_id(); |
663 | ||
664 | /* | |
665 | * Ouch, printk recursed into itself! | |
666 | */ | |
667 | if (unlikely(printk_cpu == this_cpu)) { | |
668 | /* | |
669 | * If a crash is occurring during printk() on this CPU, | |
670 | * then try to get the crash message out but make sure | |
671 | * we can't deadlock. Otherwise just return to avoid the | |
672 | * recursion and return - but flag the recursion so that | |
673 | * it can be printed at the next appropriate moment: | |
674 | */ | |
675 | if (!oops_in_progress) { | |
3b8945e8 | 676 | recursion_bug = 1; |
32a76006 IM |
677 | goto out_restore_irqs; |
678 | } | |
679 | zap_locks(); | |
680 | } | |
681 | ||
a0f1ccfd IM |
682 | lockdep_off(); |
683 | spin_lock(&logbuf_lock); | |
32a76006 | 684 | printk_cpu = this_cpu; |
1da177e4 | 685 | |
3b8945e8 TH |
686 | if (recursion_bug) { |
687 | recursion_bug = 0; | |
688 | strcpy(printk_buf, recursion_bug_msg); | |
26cc271d | 689 | printed_len = strlen(recursion_bug_msg); |
32a76006 | 690 | } |
1da177e4 | 691 | /* Emit the output into the temporary buffer */ |
32a76006 | 692 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 693 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 694 | |
ac60ad74 | 695 | |
5fd29d6c LT |
696 | p = printk_buf; |
697 | ||
698 | /* Do we have a loglevel in the string? */ | |
699 | if (p[0] == '<') { | |
700 | unsigned char c = p[1]; | |
701 | if (c && p[2] == '>') { | |
702 | switch (c) { | |
703 | case '0' ... '7': /* loglevel */ | |
704 | current_log_level = c - '0'; | |
e28d7137 LT |
705 | /* Fallthrough - make sure we're on a new line */ |
706 | case 'd': /* KERN_DEFAULT */ | |
5fd29d6c LT |
707 | if (!new_text_line) { |
708 | emit_log_char('\n'); | |
709 | new_text_line = 1; | |
710 | } | |
711 | /* Fallthrough - skip the loglevel */ | |
712 | case 'c': /* KERN_CONT */ | |
713 | p += 3; | |
714 | break; | |
715 | } | |
716 | } | |
717 | } | |
718 | ||
1da177e4 LT |
719 | /* |
720 | * Copy the output into log_buf. If the caller didn't provide | |
721 | * appropriate log level tags, we insert them here | |
722 | */ | |
5fd29d6c | 723 | for ( ; *p; p++) { |
ac60ad74 | 724 | if (new_text_line) { |
ac60ad74 NA |
725 | /* Always output the token */ |
726 | emit_log_char('<'); | |
727 | emit_log_char(current_log_level + '0'); | |
728 | emit_log_char('>'); | |
729 | printed_len += 3; | |
730 | new_text_line = 0; | |
731 | ||
1da177e4 | 732 | if (printk_time) { |
ac60ad74 | 733 | /* Follow the token with the time */ |
1da177e4 LT |
734 | char tbuf[50], *tp; |
735 | unsigned tlen; | |
736 | unsigned long long t; | |
737 | unsigned long nanosec_rem; | |
738 | ||
326e96b9 | 739 | t = cpu_clock(printk_cpu); |
1da177e4 | 740 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
741 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
742 | (unsigned long) t, | |
743 | nanosec_rem / 1000); | |
1da177e4 LT |
744 | |
745 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
746 | emit_log_char(*tp); | |
025510cd | 747 | printed_len += tlen; |
1da177e4 | 748 | } |
ac60ad74 | 749 | |
1da177e4 LT |
750 | if (!*p) |
751 | break; | |
752 | } | |
ac60ad74 | 753 | |
1da177e4 LT |
754 | emit_log_char(*p); |
755 | if (*p == '\n') | |
ac60ad74 | 756 | new_text_line = 1; |
1da177e4 LT |
757 | } |
758 | ||
266c2e0a LT |
759 | /* |
760 | * Try to acquire and then immediately release the | |
761 | * console semaphore. The release will do all the | |
762 | * actual magic (print out buffers, wake up klogd, | |
763 | * etc). | |
764 | * | |
765 | * The acquire_console_semaphore_for_printk() function | |
766 | * will release 'logbuf_lock' regardless of whether it | |
767 | * actually gets the semaphore or not. | |
768 | */ | |
769 | if (acquire_console_semaphore_for_printk(this_cpu)) | |
770 | release_console_sem(); | |
76a8ad29 | 771 | |
266c2e0a | 772 | lockdep_on(); |
32a76006 | 773 | out_restore_irqs: |
266c2e0a | 774 | raw_local_irq_restore(flags); |
76a8ad29 | 775 | |
fe21773d | 776 | preempt_enable(); |
1da177e4 LT |
777 | return printed_len; |
778 | } | |
779 | EXPORT_SYMBOL(printk); | |
780 | EXPORT_SYMBOL(vprintk); | |
781 | ||
d59745ce MM |
782 | #else |
783 | ||
eed4a2ab | 784 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
785 | { |
786 | } | |
d59745ce MM |
787 | |
788 | #endif | |
789 | ||
f7511d5f ST |
790 | static int __add_preferred_console(char *name, int idx, char *options, |
791 | char *brl_options) | |
792 | { | |
793 | struct console_cmdline *c; | |
794 | int i; | |
795 | ||
796 | /* | |
797 | * See if this tty is not yet registered, and | |
798 | * if we have a slot free. | |
799 | */ | |
800 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
801 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
802 | console_cmdline[i].index == idx) { | |
803 | if (!brl_options) | |
804 | selected_console = i; | |
805 | return 0; | |
806 | } | |
807 | if (i == MAX_CMDLINECONSOLES) | |
808 | return -E2BIG; | |
809 | if (!brl_options) | |
810 | selected_console = i; | |
811 | c = &console_cmdline[i]; | |
812 | strlcpy(c->name, name, sizeof(c->name)); | |
813 | c->options = options; | |
814 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
815 | c->brl_options = brl_options; | |
816 | #endif | |
817 | c->index = idx; | |
818 | return 0; | |
819 | } | |
2ea1c539 JB |
820 | /* |
821 | * Set up a list of consoles. Called from init/main.c | |
822 | */ | |
823 | static int __init console_setup(char *str) | |
824 | { | |
eaa944af | 825 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 826 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
827 | int idx; |
828 | ||
f7511d5f ST |
829 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
830 | if (!memcmp(str, "brl,", 4)) { | |
831 | brl_options = ""; | |
832 | str += 4; | |
833 | } else if (!memcmp(str, "brl=", 4)) { | |
834 | brl_options = str + 4; | |
835 | str = strchr(brl_options, ','); | |
836 | if (!str) { | |
837 | printk(KERN_ERR "need port name after brl=\n"); | |
838 | return 1; | |
839 | } | |
840 | *(str++) = 0; | |
841 | } | |
842 | #endif | |
843 | ||
2ea1c539 JB |
844 | /* |
845 | * Decode str into name, index, options. | |
846 | */ | |
847 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
848 | strcpy(buf, "ttyS"); |
849 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 850 | } else { |
eaa944af | 851 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 852 | } |
eaa944af | 853 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
854 | if ((options = strchr(str, ',')) != NULL) |
855 | *(options++) = 0; | |
856 | #ifdef __sparc__ | |
857 | if (!strcmp(str, "ttya")) | |
eaa944af | 858 | strcpy(buf, "ttyS0"); |
2ea1c539 | 859 | if (!strcmp(str, "ttyb")) |
eaa944af | 860 | strcpy(buf, "ttyS1"); |
2ea1c539 | 861 | #endif |
eaa944af | 862 | for (s = buf; *s; s++) |
2ea1c539 JB |
863 | if ((*s >= '0' && *s <= '9') || *s == ',') |
864 | break; | |
865 | idx = simple_strtoul(s, NULL, 10); | |
866 | *s = 0; | |
867 | ||
f7511d5f | 868 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 869 | console_set_on_cmdline = 1; |
2ea1c539 JB |
870 | return 1; |
871 | } | |
872 | __setup("console=", console_setup); | |
873 | ||
3c0547ba MM |
874 | /** |
875 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
876 | * @name: device name |
877 | * @idx: device index | |
878 | * @options: options for this console | |
3c0547ba MM |
879 | * |
880 | * The last preferred console added will be used for kernel messages | |
881 | * and stdin/out/err for init. Normally this is used by console_setup | |
882 | * above to handle user-supplied console arguments; however it can also | |
883 | * be used by arch-specific code either to override the user or more | |
884 | * commonly to provide a default console (ie from PROM variables) when | |
885 | * the user has not supplied one. | |
886 | */ | |
fb445ee5 | 887 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 888 | { |
f7511d5f | 889 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
890 | } |
891 | ||
b6b1d877 | 892 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
893 | { |
894 | struct console_cmdline *c; | |
895 | int i; | |
896 | ||
897 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
898 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
899 | console_cmdline[i].index == idx) { | |
900 | c = &console_cmdline[i]; | |
f735295b | 901 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
902 | c->name[sizeof(c->name) - 1] = 0; |
903 | c->options = options; | |
904 | c->index = idx_new; | |
905 | return i; | |
906 | } | |
907 | /* not found */ | |
908 | return -1; | |
909 | } | |
910 | ||
8f4ce8c3 AS |
911 | int console_suspend_enabled = 1; |
912 | EXPORT_SYMBOL(console_suspend_enabled); | |
913 | ||
914 | static int __init console_suspend_disable(char *str) | |
915 | { | |
916 | console_suspend_enabled = 0; | |
917 | return 1; | |
918 | } | |
919 | __setup("no_console_suspend", console_suspend_disable); | |
920 | ||
557240b4 LT |
921 | /** |
922 | * suspend_console - suspend the console subsystem | |
923 | * | |
924 | * This disables printk() while we go into suspend states | |
925 | */ | |
926 | void suspend_console(void) | |
927 | { | |
8f4ce8c3 AS |
928 | if (!console_suspend_enabled) |
929 | return; | |
0d63081d | 930 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
557240b4 LT |
931 | acquire_console_sem(); |
932 | console_suspended = 1; | |
403f3075 | 933 | up(&console_sem); |
557240b4 LT |
934 | } |
935 | ||
936 | void resume_console(void) | |
937 | { | |
8f4ce8c3 AS |
938 | if (!console_suspend_enabled) |
939 | return; | |
403f3075 | 940 | down(&console_sem); |
557240b4 LT |
941 | console_suspended = 0; |
942 | release_console_sem(); | |
943 | } | |
944 | ||
1da177e4 LT |
945 | /** |
946 | * acquire_console_sem - lock the console system for exclusive use. | |
947 | * | |
948 | * Acquires a semaphore which guarantees that the caller has | |
949 | * exclusive access to the console system and the console_drivers list. | |
950 | * | |
951 | * Can sleep, returns nothing. | |
952 | */ | |
953 | void acquire_console_sem(void) | |
954 | { | |
8abd8e29 | 955 | BUG_ON(in_interrupt()); |
1da177e4 | 956 | down(&console_sem); |
403f3075 AH |
957 | if (console_suspended) |
958 | return; | |
1da177e4 LT |
959 | console_locked = 1; |
960 | console_may_schedule = 1; | |
961 | } | |
962 | EXPORT_SYMBOL(acquire_console_sem); | |
963 | ||
964 | int try_acquire_console_sem(void) | |
965 | { | |
966 | if (down_trylock(&console_sem)) | |
967 | return -1; | |
403f3075 AH |
968 | if (console_suspended) { |
969 | up(&console_sem); | |
970 | return -1; | |
971 | } | |
1da177e4 LT |
972 | console_locked = 1; |
973 | console_may_schedule = 0; | |
974 | return 0; | |
975 | } | |
976 | EXPORT_SYMBOL(try_acquire_console_sem); | |
977 | ||
978 | int is_console_locked(void) | |
979 | { | |
980 | return console_locked; | |
981 | } | |
1da177e4 | 982 | |
b845b517 PZ |
983 | static DEFINE_PER_CPU(int, printk_pending); |
984 | ||
985 | void printk_tick(void) | |
e3e8a75d | 986 | { |
b845b517 PZ |
987 | if (__get_cpu_var(printk_pending)) { |
988 | __get_cpu_var(printk_pending) = 0; | |
e3e8a75d | 989 | wake_up_interruptible(&log_wait); |
b845b517 PZ |
990 | } |
991 | } | |
992 | ||
993 | int printk_needs_cpu(int cpu) | |
994 | { | |
995 | return per_cpu(printk_pending, cpu); | |
996 | } | |
997 | ||
998 | void wake_up_klogd(void) | |
999 | { | |
1000 | if (waitqueue_active(&log_wait)) | |
fa33507a | 1001 | __raw_get_cpu_var(printk_pending) = 1; |
e3e8a75d KK |
1002 | } |
1003 | ||
1da177e4 LT |
1004 | /** |
1005 | * release_console_sem - unlock the console system | |
1006 | * | |
1007 | * Releases the semaphore which the caller holds on the console system | |
1008 | * and the console driver list. | |
1009 | * | |
1010 | * While the semaphore was held, console output may have been buffered | |
1011 | * by printk(). If this is the case, release_console_sem() emits | |
1012 | * the output prior to releasing the semaphore. | |
1013 | * | |
1014 | * If there is output waiting for klogd, we wake it up. | |
1015 | * | |
1016 | * release_console_sem() may be called from any context. | |
1017 | */ | |
1018 | void release_console_sem(void) | |
1019 | { | |
1020 | unsigned long flags; | |
eed4a2ab DV |
1021 | unsigned _con_start, _log_end; |
1022 | unsigned wake_klogd = 0; | |
1da177e4 | 1023 | |
557240b4 | 1024 | if (console_suspended) { |
403f3075 | 1025 | up(&console_sem); |
557240b4 LT |
1026 | return; |
1027 | } | |
78944e54 AD |
1028 | |
1029 | console_may_schedule = 0; | |
1030 | ||
1da177e4 LT |
1031 | for ( ; ; ) { |
1032 | spin_lock_irqsave(&logbuf_lock, flags); | |
1033 | wake_klogd |= log_start - log_end; | |
1034 | if (con_start == log_end) | |
1035 | break; /* Nothing to print */ | |
1036 | _con_start = con_start; | |
1037 | _log_end = log_end; | |
1038 | con_start = log_end; /* Flush */ | |
1039 | spin_unlock(&logbuf_lock); | |
81d68a96 | 1040 | stop_critical_timings(); /* don't trace print latency */ |
1da177e4 | 1041 | call_console_drivers(_con_start, _log_end); |
81d68a96 | 1042 | start_critical_timings(); |
1da177e4 LT |
1043 | local_irq_restore(flags); |
1044 | } | |
1045 | console_locked = 0; | |
1da177e4 LT |
1046 | up(&console_sem); |
1047 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
1048 | if (wake_klogd) |
1049 | wake_up_klogd(); | |
1da177e4 LT |
1050 | } |
1051 | EXPORT_SYMBOL(release_console_sem); | |
1052 | ||
ddad86c2 MW |
1053 | /** |
1054 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1055 | * |
1056 | * If the console code is currently allowed to sleep, and | |
1057 | * if this CPU should yield the CPU to another task, do | |
1058 | * so here. | |
1059 | * | |
1060 | * Must be called within acquire_console_sem(). | |
1061 | */ | |
1062 | void __sched console_conditional_schedule(void) | |
1063 | { | |
1064 | if (console_may_schedule) | |
1065 | cond_resched(); | |
1066 | } | |
1067 | EXPORT_SYMBOL(console_conditional_schedule); | |
1068 | ||
1069 | void console_print(const char *s) | |
1070 | { | |
1071 | printk(KERN_EMERG "%s", s); | |
1072 | } | |
1073 | EXPORT_SYMBOL(console_print); | |
1074 | ||
1075 | void console_unblank(void) | |
1076 | { | |
1077 | struct console *c; | |
1078 | ||
1079 | /* | |
1080 | * console_unblank can no longer be called in interrupt context unless | |
1081 | * oops_in_progress is set to 1.. | |
1082 | */ | |
1083 | if (oops_in_progress) { | |
1084 | if (down_trylock(&console_sem) != 0) | |
1085 | return; | |
1086 | } else | |
1087 | acquire_console_sem(); | |
1088 | ||
1089 | console_locked = 1; | |
1090 | console_may_schedule = 0; | |
4d091611 | 1091 | for_each_console(c) |
1da177e4 LT |
1092 | if ((c->flags & CON_ENABLED) && c->unblank) |
1093 | c->unblank(); | |
1094 | release_console_sem(); | |
1095 | } | |
1da177e4 LT |
1096 | |
1097 | /* | |
1098 | * Return the console tty driver structure and its associated index | |
1099 | */ | |
1100 | struct tty_driver *console_device(int *index) | |
1101 | { | |
1102 | struct console *c; | |
1103 | struct tty_driver *driver = NULL; | |
1104 | ||
1105 | acquire_console_sem(); | |
4d091611 | 1106 | for_each_console(c) { |
1da177e4 LT |
1107 | if (!c->device) |
1108 | continue; | |
1109 | driver = c->device(c, index); | |
1110 | if (driver) | |
1111 | break; | |
1112 | } | |
1113 | release_console_sem(); | |
1114 | return driver; | |
1115 | } | |
1116 | ||
1117 | /* | |
1118 | * Prevent further output on the passed console device so that (for example) | |
1119 | * serial drivers can disable console output before suspending a port, and can | |
1120 | * re-enable output afterwards. | |
1121 | */ | |
1122 | void console_stop(struct console *console) | |
1123 | { | |
1124 | acquire_console_sem(); | |
1125 | console->flags &= ~CON_ENABLED; | |
1126 | release_console_sem(); | |
1127 | } | |
1128 | EXPORT_SYMBOL(console_stop); | |
1129 | ||
1130 | void console_start(struct console *console) | |
1131 | { | |
1132 | acquire_console_sem(); | |
1133 | console->flags |= CON_ENABLED; | |
1134 | release_console_sem(); | |
1135 | } | |
1136 | EXPORT_SYMBOL(console_start); | |
1137 | ||
1138 | /* | |
1139 | * The console driver calls this routine during kernel initialization | |
1140 | * to register the console printing procedure with printk() and to | |
1141 | * print any messages that were printed by the kernel before the | |
1142 | * console driver was initialized. | |
4d091611 RG |
1143 | * |
1144 | * This can happen pretty early during the boot process (because of | |
1145 | * early_printk) - sometimes before setup_arch() completes - be careful | |
1146 | * of what kernel features are used - they may not be initialised yet. | |
1147 | * | |
1148 | * There are two types of consoles - bootconsoles (early_printk) and | |
1149 | * "real" consoles (everything which is not a bootconsole) which are | |
1150 | * handled differently. | |
1151 | * - Any number of bootconsoles can be registered at any time. | |
1152 | * - As soon as a "real" console is registered, all bootconsoles | |
1153 | * will be unregistered automatically. | |
1154 | * - Once a "real" console is registered, any attempt to register a | |
1155 | * bootconsoles will be rejected | |
1da177e4 | 1156 | */ |
4d091611 | 1157 | void register_console(struct console *newcon) |
1da177e4 | 1158 | { |
40dc5651 | 1159 | int i; |
1da177e4 | 1160 | unsigned long flags; |
4d091611 | 1161 | struct console *bcon = NULL; |
1da177e4 | 1162 | |
4d091611 RG |
1163 | /* |
1164 | * before we register a new CON_BOOT console, make sure we don't | |
1165 | * already have a valid console | |
1166 | */ | |
1167 | if (console_drivers && newcon->flags & CON_BOOT) { | |
1168 | /* find the last or real console */ | |
1169 | for_each_console(bcon) { | |
1170 | if (!(bcon->flags & CON_BOOT)) { | |
1171 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", | |
1172 | newcon->name, newcon->index); | |
1173 | return; | |
1174 | } | |
1175 | } | |
69331af7 GH |
1176 | } |
1177 | ||
4d091611 RG |
1178 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1179 | bcon = console_drivers; | |
1180 | ||
1181 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
1182 | preferred_console = selected_console; |
1183 | ||
4d091611 RG |
1184 | if (newcon->early_setup) |
1185 | newcon->early_setup(); | |
18a8bd94 | 1186 | |
1da177e4 LT |
1187 | /* |
1188 | * See if we want to use this console driver. If we | |
1189 | * didn't select a console we take the first one | |
1190 | * that registers here. | |
1191 | */ | |
1192 | if (preferred_console < 0) { | |
4d091611 RG |
1193 | if (newcon->index < 0) |
1194 | newcon->index = 0; | |
1195 | if (newcon->setup == NULL || | |
1196 | newcon->setup(newcon, NULL) == 0) { | |
1197 | newcon->flags |= CON_ENABLED; | |
1198 | if (newcon->device) { | |
1199 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
1200 | preferred_console = 0; |
1201 | } | |
1da177e4 LT |
1202 | } |
1203 | } | |
1204 | ||
1205 | /* | |
1206 | * See if this console matches one we selected on | |
1207 | * the command line. | |
1208 | */ | |
40dc5651 JJ |
1209 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1210 | i++) { | |
4d091611 | 1211 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1da177e4 | 1212 | continue; |
4d091611 RG |
1213 | if (newcon->index >= 0 && |
1214 | newcon->index != console_cmdline[i].index) | |
1da177e4 | 1215 | continue; |
4d091611 RG |
1216 | if (newcon->index < 0) |
1217 | newcon->index = console_cmdline[i].index; | |
f7511d5f ST |
1218 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1219 | if (console_cmdline[i].brl_options) { | |
4d091611 RG |
1220 | newcon->flags |= CON_BRL; |
1221 | braille_register_console(newcon, | |
f7511d5f ST |
1222 | console_cmdline[i].index, |
1223 | console_cmdline[i].options, | |
1224 | console_cmdline[i].brl_options); | |
1225 | return; | |
1226 | } | |
1227 | #endif | |
4d091611 RG |
1228 | if (newcon->setup && |
1229 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 1230 | break; |
4d091611 RG |
1231 | newcon->flags |= CON_ENABLED; |
1232 | newcon->index = console_cmdline[i].index; | |
ab4af03a | 1233 | if (i == selected_console) { |
4d091611 | 1234 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
1235 | preferred_console = selected_console; |
1236 | } | |
1da177e4 LT |
1237 | break; |
1238 | } | |
1239 | ||
4d091611 | 1240 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
1241 | return; |
1242 | ||
4d091611 RG |
1243 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) { |
1244 | /* we need to iterate through twice, to make sure we print | |
1245 | * everything out, before we unregister the console(s) | |
1246 | */ | |
1247 | printk(KERN_INFO "console handover:"); | |
1248 | for_each_console(bcon) | |
1249 | printk("boot [%s%d] ", bcon->name, bcon->index); | |
1250 | printk(" -> real [%s%d]\n", newcon->name, newcon->index); | |
1251 | for_each_console(bcon) | |
1252 | unregister_console(bcon); | |
1253 | newcon->flags &= ~CON_PRINTBUFFER; | |
d37bf60d | 1254 | } else { |
4d091611 RG |
1255 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", |
1256 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
1257 | newcon->name, newcon->index); | |
1da177e4 LT |
1258 | } |
1259 | ||
1260 | /* | |
1261 | * Put this console in the list - keep the | |
1262 | * preferred driver at the head of the list. | |
1263 | */ | |
1264 | acquire_console_sem(); | |
4d091611 RG |
1265 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1266 | newcon->next = console_drivers; | |
1267 | console_drivers = newcon; | |
1268 | if (newcon->next) | |
1269 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 1270 | } else { |
4d091611 RG |
1271 | newcon->next = console_drivers->next; |
1272 | console_drivers->next = newcon; | |
1da177e4 | 1273 | } |
4d091611 | 1274 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 LT |
1275 | /* |
1276 | * release_console_sem() will print out the buffered messages | |
1277 | * for us. | |
1278 | */ | |
1279 | spin_lock_irqsave(&logbuf_lock, flags); | |
1280 | con_start = log_start; | |
1281 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1282 | } | |
1283 | release_console_sem(); | |
1284 | } | |
1285 | EXPORT_SYMBOL(register_console); | |
1286 | ||
40dc5651 | 1287 | int unregister_console(struct console *console) |
1da177e4 | 1288 | { |
40dc5651 | 1289 | struct console *a, *b; |
1da177e4 LT |
1290 | int res = 1; |
1291 | ||
f7511d5f ST |
1292 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1293 | if (console->flags & CON_BRL) | |
1294 | return braille_unregister_console(console); | |
1295 | #endif | |
1296 | ||
1da177e4 LT |
1297 | acquire_console_sem(); |
1298 | if (console_drivers == console) { | |
1299 | console_drivers=console->next; | |
1300 | res = 0; | |
e9b15b54 | 1301 | } else if (console_drivers) { |
1da177e4 LT |
1302 | for (a=console_drivers->next, b=console_drivers ; |
1303 | a; b=a, a=b->next) { | |
1304 | if (a == console) { | |
1305 | b->next = a->next; | |
1306 | res = 0; | |
1307 | break; | |
40dc5651 | 1308 | } |
1da177e4 LT |
1309 | } |
1310 | } | |
40dc5651 | 1311 | |
69331af7 | 1312 | /* |
ab4af03a GE |
1313 | * If this isn't the last console and it has CON_CONSDEV set, we |
1314 | * need to set it on the next preferred console. | |
1da177e4 | 1315 | */ |
69331af7 | 1316 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1317 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 LT |
1318 | |
1319 | release_console_sem(); | |
1320 | return res; | |
1321 | } | |
1322 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1323 | |
0c5564bd RG |
1324 | static int __init disable_boot_consoles(void) |
1325 | { | |
4d091611 RG |
1326 | struct console *con; |
1327 | ||
1328 | for_each_console(con) { | |
1329 | if (con->flags & CON_BOOT) { | |
cb00e99c | 1330 | printk(KERN_INFO "turn off boot console %s%d\n", |
4d091611 RG |
1331 | con->name, con->index); |
1332 | return unregister_console(con); | |
cb00e99c | 1333 | } |
0c5564bd RG |
1334 | } |
1335 | return 0; | |
1336 | } | |
1337 | late_initcall(disable_boot_consoles); | |
1338 | ||
7ef3d2fd | 1339 | #if defined CONFIG_PRINTK |
717115e1 | 1340 | |
1da177e4 LT |
1341 | /* |
1342 | * printk rate limiting, lifted from the networking subsystem. | |
1343 | * | |
641de9d8 UKK |
1344 | * This enforces a rate limit: not more than 10 kernel messages |
1345 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 1346 | */ |
641de9d8 UKK |
1347 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1348 | ||
1da177e4 LT |
1349 | int printk_ratelimit(void) |
1350 | { | |
717115e1 | 1351 | return __ratelimit(&printk_ratelimit_state); |
1da177e4 LT |
1352 | } |
1353 | EXPORT_SYMBOL(printk_ratelimit); | |
f46c4833 AM |
1354 | |
1355 | /** | |
1356 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1357 | * @caller_jiffies: pointer to caller's state | |
1358 | * @interval_msecs: minimum interval between prints | |
1359 | * | |
1360 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1361 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1362 | * returned true. | |
1363 | */ | |
1364 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1365 | unsigned int interval_msecs) | |
1366 | { | |
f2d28a2e GK |
1367 | if (*caller_jiffies == 0 |
1368 | || !time_in_range(jiffies, *caller_jiffies, | |
1369 | *caller_jiffies | |
1370 | + msecs_to_jiffies(interval_msecs))) { | |
1371 | *caller_jiffies = jiffies; | |
f46c4833 AM |
1372 | return true; |
1373 | } | |
1374 | return false; | |
1375 | } | |
1376 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
7ef3d2fd | 1377 | #endif |