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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/kernel/printk.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * Modified to make sys_syslog() more flexible: added commands to | |
7 | * return the last 4k of kernel messages, regardless of whether | |
8 | * they've been read or not. Added option to suppress kernel printk's | |
9 | * to the console. Added hook for sending the console messages | |
10 | * elsewhere, in preparation for a serial line console (someday). | |
11 | * Ted Ts'o, 2/11/93. | |
12 | * Modified for sysctl support, 1/8/97, Chris Horn. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 | 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> |
3fff4c42 | 36 | #include <linux/ratelimit.h> |
456b565c | 37 | #include <linux/kmsg_dump.h> |
00234592 | 38 | #include <linux/syslog.h> |
1da177e4 LT |
39 | |
40 | #include <asm/uaccess.h> | |
41 | ||
4d091611 RG |
42 | /* |
43 | * for_each_console() allows you to iterate on each console | |
44 | */ | |
45 | #define for_each_console(con) \ | |
46 | for (con = console_drivers; con != NULL; con = con->next) | |
47 | ||
076f9776 IM |
48 | /* |
49 | * Architectures can override it: | |
50 | */ | |
e17ba73b | 51 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
076f9776 IM |
52 | { |
53 | } | |
54 | ||
1da177e4 LT |
55 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
56 | ||
57 | /* printk's without a loglevel use this.. */ | |
58 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ | |
59 | ||
60 | /* We show everything that is MORE important than this.. */ | |
61 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
62 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
63 | ||
64 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
65 | ||
66 | int console_printk[4] = { | |
67 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
68 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
69 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
70 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
71 | }; | |
72 | ||
1aaad49e FP |
73 | static int saved_console_loglevel = -1; |
74 | ||
1da177e4 | 75 | /* |
0bbfb7c2 | 76 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
77 | * their unblank() callback or not. So let's export it. |
78 | */ | |
79 | int oops_in_progress; | |
80 | EXPORT_SYMBOL(oops_in_progress); | |
81 | ||
82 | /* | |
83 | * console_sem protects the console_drivers list, and also | |
84 | * provides serialisation for access to the entire console | |
85 | * driver system. | |
86 | */ | |
87 | static DECLARE_MUTEX(console_sem); | |
88 | struct console *console_drivers; | |
a29d1cfe IM |
89 | EXPORT_SYMBOL_GPL(console_drivers); |
90 | ||
1da177e4 LT |
91 | /* |
92 | * This is used for debugging the mess that is the VT code by | |
93 | * keeping track if we have the console semaphore held. It's | |
94 | * definitely not the perfect debug tool (we don't know if _WE_ | |
95 | * hold it are racing, but it helps tracking those weird code | |
96 | * path in the console code where we end up in places I want | |
97 | * locked without the console sempahore held | |
98 | */ | |
557240b4 | 99 | static int console_locked, console_suspended; |
1da177e4 LT |
100 | |
101 | /* | |
102 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
103 | * It is also used in interesting ways to provide interlocking in | |
104 | * release_console_sem(). | |
105 | */ | |
106 | static DEFINE_SPINLOCK(logbuf_lock); | |
107 | ||
eed4a2ab | 108 | #define LOG_BUF_MASK (log_buf_len-1) |
1da177e4 LT |
109 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
110 | ||
111 | /* | |
112 | * The indices into log_buf are not constrained to log_buf_len - they | |
113 | * must be masked before subscripting | |
114 | */ | |
eed4a2ab DV |
115 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
116 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ | |
117 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
118 | |
119 | /* | |
120 | * Array of consoles built from command line options (console=) | |
121 | */ | |
122 | struct console_cmdline | |
123 | { | |
124 | char name[8]; /* Name of the driver */ | |
125 | int index; /* Minor dev. to use */ | |
126 | char *options; /* Options for the driver */ | |
f7511d5f ST |
127 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
128 | char *brl_options; /* Options for braille driver */ | |
129 | #endif | |
1da177e4 LT |
130 | }; |
131 | ||
132 | #define MAX_CMDLINECONSOLES 8 | |
133 | ||
134 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
135 | static int selected_console = -1; | |
136 | static int preferred_console = -1; | |
9e124fe1 MA |
137 | int console_set_on_cmdline; |
138 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
139 | |
140 | /* Flag: console code may call schedule() */ | |
141 | static int console_may_schedule; | |
142 | ||
d59745ce MM |
143 | #ifdef CONFIG_PRINTK |
144 | ||
145 | static char __log_buf[__LOG_BUF_LEN]; | |
146 | static char *log_buf = __log_buf; | |
147 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 148 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
d59745ce | 149 | |
04d491ab NH |
150 | #ifdef CONFIG_KEXEC |
151 | /* | |
152 | * This appends the listed symbols to /proc/vmcoreinfo | |
153 | * | |
154 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
155 | * obtain access to symbols that are otherwise very difficult to locate. These | |
156 | * symbols are specifically used so that utilities can access and extract the | |
157 | * dmesg log from a vmcore file after a crash. | |
158 | */ | |
159 | void log_buf_kexec_setup(void) | |
160 | { | |
161 | VMCOREINFO_SYMBOL(log_buf); | |
162 | VMCOREINFO_SYMBOL(log_end); | |
163 | VMCOREINFO_SYMBOL(log_buf_len); | |
164 | VMCOREINFO_SYMBOL(logged_chars); | |
165 | } | |
166 | #endif | |
167 | ||
1da177e4 LT |
168 | static int __init log_buf_len_setup(char *str) |
169 | { | |
eed4a2ab | 170 | unsigned size = memparse(str, &str); |
1da177e4 LT |
171 | unsigned long flags; |
172 | ||
173 | if (size) | |
174 | size = roundup_pow_of_two(size); | |
175 | if (size > log_buf_len) { | |
eed4a2ab | 176 | unsigned start, dest_idx, offset; |
40dc5651 | 177 | char *new_log_buf; |
1da177e4 LT |
178 | |
179 | new_log_buf = alloc_bootmem(size); | |
180 | if (!new_log_buf) { | |
40dc5651 | 181 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
182 | goto out; |
183 | } | |
184 | ||
185 | spin_lock_irqsave(&logbuf_lock, flags); | |
186 | log_buf_len = size; | |
187 | log_buf = new_log_buf; | |
188 | ||
189 | offset = start = min(con_start, log_start); | |
190 | dest_idx = 0; | |
191 | while (start != log_end) { | |
192 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
193 | start++; | |
194 | dest_idx++; | |
195 | } | |
196 | log_start -= offset; | |
197 | con_start -= offset; | |
198 | log_end -= offset; | |
199 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
200 | ||
40dc5651 | 201 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
202 | } |
203 | out: | |
1da177e4 LT |
204 | return 1; |
205 | } | |
206 | ||
207 | __setup("log_buf_len=", log_buf_len_setup); | |
208 | ||
bfe8df3d RD |
209 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
210 | ||
211 | static unsigned int boot_delay; /* msecs delay after each printk during bootup */ | |
3a3b6ed2 | 212 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
213 | |
214 | static int __init boot_delay_setup(char *str) | |
215 | { | |
216 | unsigned long lpj; | |
bfe8df3d RD |
217 | |
218 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
219 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
220 | ||
221 | get_option(&str, &boot_delay); | |
222 | if (boot_delay > 10 * 1000) | |
223 | boot_delay = 0; | |
224 | ||
3a3b6ed2 DY |
225 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
226 | "HZ: %d, loops_per_msec: %llu\n", | |
227 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
bfe8df3d RD |
228 | return 1; |
229 | } | |
230 | __setup("boot_delay=", boot_delay_setup); | |
231 | ||
232 | static void boot_delay_msec(void) | |
233 | { | |
234 | unsigned long long k; | |
235 | unsigned long timeout; | |
236 | ||
237 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
238 | return; | |
239 | ||
3a3b6ed2 | 240 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
241 | |
242 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
243 | while (k) { | |
244 | k--; | |
245 | cpu_relax(); | |
246 | /* | |
247 | * use (volatile) jiffies to prevent | |
248 | * compiler reduction; loop termination via jiffies | |
249 | * is secondary and may or may not happen. | |
250 | */ | |
251 | if (time_after(jiffies, timeout)) | |
252 | break; | |
253 | touch_nmi_watchdog(); | |
254 | } | |
255 | } | |
256 | #else | |
257 | static inline void boot_delay_msec(void) | |
258 | { | |
259 | } | |
260 | #endif | |
261 | ||
00234592 | 262 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
1da177e4 | 263 | { |
eed4a2ab | 264 | unsigned i, j, limit, count; |
1da177e4 LT |
265 | int do_clear = 0; |
266 | char c; | |
267 | int error = 0; | |
268 | ||
00234592 | 269 | error = security_syslog(type, from_file); |
1da177e4 LT |
270 | if (error) |
271 | return error; | |
272 | ||
273 | switch (type) { | |
d78ca3cd | 274 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 275 | break; |
d78ca3cd | 276 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 277 | break; |
d78ca3cd | 278 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 LT |
279 | error = -EINVAL; |
280 | if (!buf || len < 0) | |
281 | goto out; | |
282 | error = 0; | |
283 | if (!len) | |
284 | goto out; | |
285 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
286 | error = -EFAULT; | |
287 | goto out; | |
288 | } | |
40dc5651 JJ |
289 | error = wait_event_interruptible(log_wait, |
290 | (log_start - log_end)); | |
1da177e4 LT |
291 | if (error) |
292 | goto out; | |
293 | i = 0; | |
294 | spin_lock_irq(&logbuf_lock); | |
295 | while (!error && (log_start != log_end) && i < len) { | |
296 | c = LOG_BUF(log_start); | |
297 | log_start++; | |
298 | spin_unlock_irq(&logbuf_lock); | |
299 | error = __put_user(c,buf); | |
300 | buf++; | |
301 | i++; | |
302 | cond_resched(); | |
303 | spin_lock_irq(&logbuf_lock); | |
304 | } | |
305 | spin_unlock_irq(&logbuf_lock); | |
306 | if (!error) | |
307 | error = i; | |
308 | break; | |
d78ca3cd KC |
309 | /* Read/clear last kernel messages */ |
310 | case SYSLOG_ACTION_READ_CLEAR: | |
40dc5651 | 311 | do_clear = 1; |
1da177e4 | 312 | /* FALL THRU */ |
d78ca3cd KC |
313 | /* Read last kernel messages */ |
314 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 LT |
315 | error = -EINVAL; |
316 | if (!buf || len < 0) | |
317 | goto out; | |
318 | error = 0; | |
319 | if (!len) | |
320 | goto out; | |
321 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
322 | error = -EFAULT; | |
323 | goto out; | |
324 | } | |
325 | count = len; | |
326 | if (count > log_buf_len) | |
327 | count = log_buf_len; | |
328 | spin_lock_irq(&logbuf_lock); | |
329 | if (count > logged_chars) | |
330 | count = logged_chars; | |
331 | if (do_clear) | |
332 | logged_chars = 0; | |
333 | limit = log_end; | |
334 | /* | |
335 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 336 | * printk() could overwrite the messages |
1da177e4 LT |
337 | * we try to copy to user space. Therefore |
338 | * the messages are copied in reverse. <manfreds> | |
339 | */ | |
40dc5651 | 340 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
341 | j = limit-1-i; |
342 | if (j + log_buf_len < log_end) | |
343 | break; | |
344 | c = LOG_BUF(j); | |
345 | spin_unlock_irq(&logbuf_lock); | |
346 | error = __put_user(c,&buf[count-1-i]); | |
347 | cond_resched(); | |
348 | spin_lock_irq(&logbuf_lock); | |
349 | } | |
350 | spin_unlock_irq(&logbuf_lock); | |
351 | if (error) | |
352 | break; | |
353 | error = i; | |
40dc5651 | 354 | if (i != count) { |
1da177e4 LT |
355 | int offset = count-error; |
356 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 357 | for (i = 0; i < error; i++) { |
1da177e4 LT |
358 | if (__get_user(c,&buf[i+offset]) || |
359 | __put_user(c,&buf[i])) { | |
360 | error = -EFAULT; | |
361 | break; | |
362 | } | |
363 | cond_resched(); | |
364 | } | |
365 | } | |
366 | break; | |
d78ca3cd KC |
367 | /* Clear ring buffer */ |
368 | case SYSLOG_ACTION_CLEAR: | |
1da177e4 LT |
369 | logged_chars = 0; |
370 | break; | |
d78ca3cd KC |
371 | /* Disable logging to console */ |
372 | case SYSLOG_ACTION_CONSOLE_OFF: | |
1aaad49e FP |
373 | if (saved_console_loglevel == -1) |
374 | saved_console_loglevel = console_loglevel; | |
1da177e4 LT |
375 | console_loglevel = minimum_console_loglevel; |
376 | break; | |
d78ca3cd KC |
377 | /* Enable logging to console */ |
378 | case SYSLOG_ACTION_CONSOLE_ON: | |
1aaad49e FP |
379 | if (saved_console_loglevel != -1) { |
380 | console_loglevel = saved_console_loglevel; | |
381 | saved_console_loglevel = -1; | |
382 | } | |
1da177e4 | 383 | break; |
d78ca3cd KC |
384 | /* Set level of messages printed to console */ |
385 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 LT |
386 | error = -EINVAL; |
387 | if (len < 1 || len > 8) | |
388 | goto out; | |
389 | if (len < minimum_console_loglevel) | |
390 | len = minimum_console_loglevel; | |
391 | console_loglevel = len; | |
1aaad49e FP |
392 | /* Implicitly re-enable logging to console */ |
393 | saved_console_loglevel = -1; | |
1da177e4 LT |
394 | error = 0; |
395 | break; | |
d78ca3cd KC |
396 | /* Number of chars in the log buffer */ |
397 | case SYSLOG_ACTION_SIZE_UNREAD: | |
1da177e4 LT |
398 | error = log_end - log_start; |
399 | break; | |
d78ca3cd KC |
400 | /* Size of the log buffer */ |
401 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
402 | error = log_buf_len; |
403 | break; | |
404 | default: | |
405 | error = -EINVAL; | |
406 | break; | |
407 | } | |
408 | out: | |
409 | return error; | |
410 | } | |
411 | ||
1e7bfb21 | 412 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 413 | { |
00234592 | 414 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
1da177e4 LT |
415 | } |
416 | ||
417 | /* | |
418 | * Call the console drivers on a range of log_buf | |
419 | */ | |
eed4a2ab | 420 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
421 | { |
422 | struct console *con; | |
423 | ||
4d091611 | 424 | for_each_console(con) { |
76a8ad29 ME |
425 | if ((con->flags & CON_ENABLED) && con->write && |
426 | (cpu_online(smp_processor_id()) || | |
427 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
428 | con->write(con, &LOG_BUF(start), end - start); |
429 | } | |
430 | } | |
431 | ||
79290822 IM |
432 | static int __read_mostly ignore_loglevel; |
433 | ||
99eea6a1 | 434 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
435 | { |
436 | ignore_loglevel = 1; | |
437 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
438 | ||
c4772d99 | 439 | return 0; |
79290822 IM |
440 | } |
441 | ||
c4772d99 | 442 | early_param("ignore_loglevel", ignore_loglevel_setup); |
79290822 | 443 | |
1da177e4 LT |
444 | /* |
445 | * Write out chars from start to end - 1 inclusive | |
446 | */ | |
eed4a2ab DV |
447 | static void _call_console_drivers(unsigned start, |
448 | unsigned end, int msg_log_level) | |
1da177e4 | 449 | { |
79290822 | 450 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
451 | console_drivers && start != end) { |
452 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
453 | /* wrapped write */ | |
454 | __call_console_drivers(start & LOG_BUF_MASK, | |
455 | log_buf_len); | |
456 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
457 | } else { | |
458 | __call_console_drivers(start, end); | |
459 | } | |
460 | } | |
461 | } | |
462 | ||
463 | /* | |
464 | * Call the console drivers, asking them to write out | |
465 | * log_buf[start] to log_buf[end - 1]. | |
466 | * The console_sem must be held. | |
467 | */ | |
eed4a2ab | 468 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 469 | { |
eed4a2ab | 470 | unsigned cur_index, start_print; |
1da177e4 LT |
471 | static int msg_level = -1; |
472 | ||
eed4a2ab | 473 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
474 | |
475 | cur_index = start; | |
476 | start_print = start; | |
477 | while (cur_index != end) { | |
40dc5651 JJ |
478 | if (msg_level < 0 && ((end - cur_index) > 2) && |
479 | LOG_BUF(cur_index + 0) == '<' && | |
480 | LOG_BUF(cur_index + 1) >= '0' && | |
481 | LOG_BUF(cur_index + 1) <= '7' && | |
482 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
483 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
484 | cur_index += 3; | |
485 | start_print = cur_index; | |
486 | } | |
487 | while (cur_index != end) { | |
488 | char c = LOG_BUF(cur_index); | |
1da177e4 | 489 | |
40dc5651 | 490 | cur_index++; |
1da177e4 LT |
491 | if (c == '\n') { |
492 | if (msg_level < 0) { | |
493 | /* | |
494 | * printk() has already given us loglevel tags in | |
495 | * the buffer. This code is here in case the | |
496 | * log buffer has wrapped right round and scribbled | |
497 | * on those tags | |
498 | */ | |
499 | msg_level = default_message_loglevel; | |
500 | } | |
501 | _call_console_drivers(start_print, cur_index, msg_level); | |
502 | msg_level = -1; | |
503 | start_print = cur_index; | |
504 | break; | |
505 | } | |
506 | } | |
507 | } | |
508 | _call_console_drivers(start_print, end, msg_level); | |
509 | } | |
510 | ||
511 | static void emit_log_char(char c) | |
512 | { | |
513 | LOG_BUF(log_end) = c; | |
514 | log_end++; | |
515 | if (log_end - log_start > log_buf_len) | |
516 | log_start = log_end - log_buf_len; | |
517 | if (log_end - con_start > log_buf_len) | |
518 | con_start = log_end - log_buf_len; | |
519 | if (logged_chars < log_buf_len) | |
520 | logged_chars++; | |
521 | } | |
522 | ||
523 | /* | |
524 | * Zap console related locks when oopsing. Only zap at most once | |
525 | * every 10 seconds, to leave time for slow consoles to print a | |
526 | * full oops. | |
527 | */ | |
528 | static void zap_locks(void) | |
529 | { | |
530 | static unsigned long oops_timestamp; | |
531 | ||
532 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 533 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
534 | return; |
535 | ||
536 | oops_timestamp = jiffies; | |
537 | ||
538 | /* If a crash is occurring, make sure we can't deadlock */ | |
539 | spin_lock_init(&logbuf_lock); | |
540 | /* And make sure that we print immediately */ | |
541 | init_MUTEX(&console_sem); | |
542 | } | |
543 | ||
544 | #if defined(CONFIG_PRINTK_TIME) | |
545 | static int printk_time = 1; | |
546 | #else | |
547 | static int printk_time = 0; | |
548 | #endif | |
e84845c4 | 549 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 550 | |
76a8ad29 ME |
551 | /* Check if we have any console registered that can be called early in boot. */ |
552 | static int have_callable_console(void) | |
553 | { | |
554 | struct console *con; | |
555 | ||
4d091611 | 556 | for_each_console(con) |
76a8ad29 ME |
557 | if (con->flags & CON_ANYTIME) |
558 | return 1; | |
559 | ||
560 | return 0; | |
561 | } | |
562 | ||
ddad86c2 MW |
563 | /** |
564 | * printk - print a kernel message | |
565 | * @fmt: format string | |
566 | * | |
72fd4a35 | 567 | * This is printk(). It can be called from any context. We want it to work. |
40dc5651 | 568 | * |
1da177e4 LT |
569 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
570 | * call the console drivers. If we fail to get the semaphore we place the output | |
571 | * into the log buffer and return. The current holder of the console_sem will | |
572 | * notice the new output in release_console_sem() and will send it to the | |
573 | * consoles before releasing the semaphore. | |
574 | * | |
575 | * One effect of this deferred printing is that code which calls printk() and | |
576 | * then changes console_loglevel may break. This is because console_loglevel | |
577 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
578 | * |
579 | * See also: | |
580 | * printf(3) | |
20036fdc AK |
581 | * |
582 | * See the vsnprintf() documentation for format string extensions over C99. | |
1da177e4 | 583 | */ |
d59745ce | 584 | |
1da177e4 LT |
585 | asmlinkage int printk(const char *fmt, ...) |
586 | { | |
587 | va_list args; | |
588 | int r; | |
589 | ||
590 | va_start(args, fmt); | |
591 | r = vprintk(fmt, args); | |
592 | va_end(args); | |
593 | ||
594 | return r; | |
595 | } | |
596 | ||
fe21773d DH |
597 | /* cpu currently holding logbuf_lock */ |
598 | static volatile unsigned int printk_cpu = UINT_MAX; | |
599 | ||
266c2e0a LT |
600 | /* |
601 | * Can we actually use the console at this time on this cpu? | |
602 | * | |
603 | * Console drivers may assume that per-cpu resources have | |
604 | * been allocated. So unless they're explicitly marked as | |
605 | * being able to cope (CON_ANYTIME) don't call them until | |
606 | * this CPU is officially up. | |
607 | */ | |
608 | static inline int can_use_console(unsigned int cpu) | |
609 | { | |
610 | return cpu_online(cpu) || have_callable_console(); | |
611 | } | |
612 | ||
613 | /* | |
614 | * Try to get console ownership to actually show the kernel | |
615 | * messages from a 'printk'. Return true (and with the | |
616 | * console_semaphore held, and 'console_locked' set) if it | |
617 | * is successful, false otherwise. | |
618 | * | |
619 | * This gets called with the 'logbuf_lock' spinlock held and | |
620 | * interrupts disabled. It should return with 'lockbuf_lock' | |
621 | * released but interrupts still disabled. | |
622 | */ | |
623 | static int acquire_console_semaphore_for_printk(unsigned int cpu) | |
624 | { | |
625 | int retval = 0; | |
626 | ||
093a07e2 LT |
627 | if (!try_acquire_console_sem()) { |
628 | retval = 1; | |
629 | ||
630 | /* | |
631 | * If we can't use the console, we need to release | |
632 | * the console semaphore by hand to avoid flushing | |
633 | * the buffer. We need to hold the console semaphore | |
634 | * in order to do this test safely. | |
635 | */ | |
636 | if (!can_use_console(cpu)) { | |
637 | console_locked = 0; | |
638 | up(&console_sem); | |
639 | retval = 0; | |
640 | } | |
641 | } | |
266c2e0a LT |
642 | printk_cpu = UINT_MAX; |
643 | spin_unlock(&logbuf_lock); | |
644 | return retval; | |
645 | } | |
3b8945e8 TH |
646 | static const char recursion_bug_msg [] = |
647 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
648 | static int recursion_bug; | |
edb123e1 | 649 | static int new_text_line = 1; |
3b8945e8 | 650 | static char printk_buf[1024]; |
32a76006 | 651 | |
af91322e DY |
652 | int printk_delay_msec __read_mostly; |
653 | ||
654 | static inline void printk_delay(void) | |
655 | { | |
656 | if (unlikely(printk_delay_msec)) { | |
657 | int m = printk_delay_msec; | |
658 | ||
659 | while (m--) { | |
660 | mdelay(1); | |
661 | touch_nmi_watchdog(); | |
662 | } | |
663 | } | |
664 | } | |
665 | ||
1da177e4 LT |
666 | asmlinkage int vprintk(const char *fmt, va_list args) |
667 | { | |
32a76006 | 668 | int printed_len = 0; |
09159308 | 669 | int current_log_level = default_message_loglevel; |
ac60ad74 | 670 | unsigned long flags; |
32a76006 | 671 | int this_cpu; |
1da177e4 | 672 | char *p; |
1da177e4 | 673 | |
bfe8df3d | 674 | boot_delay_msec(); |
af91322e | 675 | printk_delay(); |
bfe8df3d | 676 | |
fe21773d | 677 | preempt_disable(); |
1da177e4 | 678 | /* This stops the holder of console_sem just where we want him */ |
1efc5da3 | 679 | raw_local_irq_save(flags); |
32a76006 IM |
680 | this_cpu = smp_processor_id(); |
681 | ||
682 | /* | |
683 | * Ouch, printk recursed into itself! | |
684 | */ | |
685 | if (unlikely(printk_cpu == this_cpu)) { | |
686 | /* | |
687 | * If a crash is occurring during printk() on this CPU, | |
688 | * then try to get the crash message out but make sure | |
689 | * we can't deadlock. Otherwise just return to avoid the | |
690 | * recursion and return - but flag the recursion so that | |
691 | * it can be printed at the next appropriate moment: | |
692 | */ | |
693 | if (!oops_in_progress) { | |
3b8945e8 | 694 | recursion_bug = 1; |
32a76006 IM |
695 | goto out_restore_irqs; |
696 | } | |
697 | zap_locks(); | |
698 | } | |
699 | ||
a0f1ccfd IM |
700 | lockdep_off(); |
701 | spin_lock(&logbuf_lock); | |
32a76006 | 702 | printk_cpu = this_cpu; |
1da177e4 | 703 | |
3b8945e8 TH |
704 | if (recursion_bug) { |
705 | recursion_bug = 0; | |
706 | strcpy(printk_buf, recursion_bug_msg); | |
26cc271d | 707 | printed_len = strlen(recursion_bug_msg); |
32a76006 | 708 | } |
1da177e4 | 709 | /* Emit the output into the temporary buffer */ |
32a76006 | 710 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 711 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 712 | |
ac60ad74 | 713 | |
5fd29d6c LT |
714 | p = printk_buf; |
715 | ||
716 | /* Do we have a loglevel in the string? */ | |
717 | if (p[0] == '<') { | |
718 | unsigned char c = p[1]; | |
719 | if (c && p[2] == '>') { | |
720 | switch (c) { | |
721 | case '0' ... '7': /* loglevel */ | |
722 | current_log_level = c - '0'; | |
e28d7137 LT |
723 | /* Fallthrough - make sure we're on a new line */ |
724 | case 'd': /* KERN_DEFAULT */ | |
5fd29d6c LT |
725 | if (!new_text_line) { |
726 | emit_log_char('\n'); | |
727 | new_text_line = 1; | |
728 | } | |
729 | /* Fallthrough - skip the loglevel */ | |
730 | case 'c': /* KERN_CONT */ | |
731 | p += 3; | |
732 | break; | |
733 | } | |
734 | } | |
735 | } | |
736 | ||
1da177e4 LT |
737 | /* |
738 | * Copy the output into log_buf. If the caller didn't provide | |
739 | * appropriate log level tags, we insert them here | |
740 | */ | |
5fd29d6c | 741 | for ( ; *p; p++) { |
ac60ad74 | 742 | if (new_text_line) { |
ac60ad74 NA |
743 | /* Always output the token */ |
744 | emit_log_char('<'); | |
745 | emit_log_char(current_log_level + '0'); | |
746 | emit_log_char('>'); | |
747 | printed_len += 3; | |
748 | new_text_line = 0; | |
749 | ||
1da177e4 | 750 | if (printk_time) { |
ac60ad74 | 751 | /* Follow the token with the time */ |
1da177e4 LT |
752 | char tbuf[50], *tp; |
753 | unsigned tlen; | |
754 | unsigned long long t; | |
755 | unsigned long nanosec_rem; | |
756 | ||
326e96b9 | 757 | t = cpu_clock(printk_cpu); |
1da177e4 | 758 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
759 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
760 | (unsigned long) t, | |
761 | nanosec_rem / 1000); | |
1da177e4 LT |
762 | |
763 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
764 | emit_log_char(*tp); | |
025510cd | 765 | printed_len += tlen; |
1da177e4 | 766 | } |
ac60ad74 | 767 | |
1da177e4 LT |
768 | if (!*p) |
769 | break; | |
770 | } | |
ac60ad74 | 771 | |
1da177e4 LT |
772 | emit_log_char(*p); |
773 | if (*p == '\n') | |
ac60ad74 | 774 | new_text_line = 1; |
1da177e4 LT |
775 | } |
776 | ||
266c2e0a LT |
777 | /* |
778 | * Try to acquire and then immediately release the | |
779 | * console semaphore. The release will do all the | |
780 | * actual magic (print out buffers, wake up klogd, | |
781 | * etc). | |
782 | * | |
783 | * The acquire_console_semaphore_for_printk() function | |
784 | * will release 'logbuf_lock' regardless of whether it | |
785 | * actually gets the semaphore or not. | |
786 | */ | |
787 | if (acquire_console_semaphore_for_printk(this_cpu)) | |
788 | release_console_sem(); | |
76a8ad29 | 789 | |
266c2e0a | 790 | lockdep_on(); |
32a76006 | 791 | out_restore_irqs: |
266c2e0a | 792 | raw_local_irq_restore(flags); |
76a8ad29 | 793 | |
fe21773d | 794 | preempt_enable(); |
1da177e4 LT |
795 | return printed_len; |
796 | } | |
797 | EXPORT_SYMBOL(printk); | |
798 | EXPORT_SYMBOL(vprintk); | |
799 | ||
d59745ce MM |
800 | #else |
801 | ||
eed4a2ab | 802 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
803 | { |
804 | } | |
d59745ce MM |
805 | |
806 | #endif | |
807 | ||
f7511d5f ST |
808 | static int __add_preferred_console(char *name, int idx, char *options, |
809 | char *brl_options) | |
810 | { | |
811 | struct console_cmdline *c; | |
812 | int i; | |
813 | ||
814 | /* | |
815 | * See if this tty is not yet registered, and | |
816 | * if we have a slot free. | |
817 | */ | |
818 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
819 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
820 | console_cmdline[i].index == idx) { | |
821 | if (!brl_options) | |
822 | selected_console = i; | |
823 | return 0; | |
824 | } | |
825 | if (i == MAX_CMDLINECONSOLES) | |
826 | return -E2BIG; | |
827 | if (!brl_options) | |
828 | selected_console = i; | |
829 | c = &console_cmdline[i]; | |
830 | strlcpy(c->name, name, sizeof(c->name)); | |
831 | c->options = options; | |
832 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
833 | c->brl_options = brl_options; | |
834 | #endif | |
835 | c->index = idx; | |
836 | return 0; | |
837 | } | |
2ea1c539 JB |
838 | /* |
839 | * Set up a list of consoles. Called from init/main.c | |
840 | */ | |
841 | static int __init console_setup(char *str) | |
842 | { | |
eaa944af | 843 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 844 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
845 | int idx; |
846 | ||
f7511d5f ST |
847 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
848 | if (!memcmp(str, "brl,", 4)) { | |
849 | brl_options = ""; | |
850 | str += 4; | |
851 | } else if (!memcmp(str, "brl=", 4)) { | |
852 | brl_options = str + 4; | |
853 | str = strchr(brl_options, ','); | |
854 | if (!str) { | |
855 | printk(KERN_ERR "need port name after brl=\n"); | |
856 | return 1; | |
857 | } | |
858 | *(str++) = 0; | |
859 | } | |
860 | #endif | |
861 | ||
2ea1c539 JB |
862 | /* |
863 | * Decode str into name, index, options. | |
864 | */ | |
865 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
866 | strcpy(buf, "ttyS"); |
867 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 868 | } else { |
eaa944af | 869 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 870 | } |
eaa944af | 871 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
872 | if ((options = strchr(str, ',')) != NULL) |
873 | *(options++) = 0; | |
874 | #ifdef __sparc__ | |
875 | if (!strcmp(str, "ttya")) | |
eaa944af | 876 | strcpy(buf, "ttyS0"); |
2ea1c539 | 877 | if (!strcmp(str, "ttyb")) |
eaa944af | 878 | strcpy(buf, "ttyS1"); |
2ea1c539 | 879 | #endif |
eaa944af | 880 | for (s = buf; *s; s++) |
2ea1c539 JB |
881 | if ((*s >= '0' && *s <= '9') || *s == ',') |
882 | break; | |
883 | idx = simple_strtoul(s, NULL, 10); | |
884 | *s = 0; | |
885 | ||
f7511d5f | 886 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 887 | console_set_on_cmdline = 1; |
2ea1c539 JB |
888 | return 1; |
889 | } | |
890 | __setup("console=", console_setup); | |
891 | ||
3c0547ba MM |
892 | /** |
893 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
894 | * @name: device name |
895 | * @idx: device index | |
896 | * @options: options for this console | |
3c0547ba MM |
897 | * |
898 | * The last preferred console added will be used for kernel messages | |
899 | * and stdin/out/err for init. Normally this is used by console_setup | |
900 | * above to handle user-supplied console arguments; however it can also | |
901 | * be used by arch-specific code either to override the user or more | |
902 | * commonly to provide a default console (ie from PROM variables) when | |
903 | * the user has not supplied one. | |
904 | */ | |
fb445ee5 | 905 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 906 | { |
f7511d5f | 907 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
908 | } |
909 | ||
b6b1d877 | 910 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
911 | { |
912 | struct console_cmdline *c; | |
913 | int i; | |
914 | ||
915 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
916 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
917 | console_cmdline[i].index == idx) { | |
918 | c = &console_cmdline[i]; | |
f735295b | 919 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
920 | c->name[sizeof(c->name) - 1] = 0; |
921 | c->options = options; | |
922 | c->index = idx_new; | |
923 | return i; | |
924 | } | |
925 | /* not found */ | |
926 | return -1; | |
927 | } | |
928 | ||
8f4ce8c3 AS |
929 | int console_suspend_enabled = 1; |
930 | EXPORT_SYMBOL(console_suspend_enabled); | |
931 | ||
932 | static int __init console_suspend_disable(char *str) | |
933 | { | |
934 | console_suspend_enabled = 0; | |
935 | return 1; | |
936 | } | |
937 | __setup("no_console_suspend", console_suspend_disable); | |
938 | ||
557240b4 LT |
939 | /** |
940 | * suspend_console - suspend the console subsystem | |
941 | * | |
942 | * This disables printk() while we go into suspend states | |
943 | */ | |
944 | void suspend_console(void) | |
945 | { | |
8f4ce8c3 AS |
946 | if (!console_suspend_enabled) |
947 | return; | |
0d63081d | 948 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
557240b4 LT |
949 | acquire_console_sem(); |
950 | console_suspended = 1; | |
403f3075 | 951 | up(&console_sem); |
557240b4 LT |
952 | } |
953 | ||
954 | void resume_console(void) | |
955 | { | |
8f4ce8c3 AS |
956 | if (!console_suspend_enabled) |
957 | return; | |
403f3075 | 958 | down(&console_sem); |
557240b4 LT |
959 | console_suspended = 0; |
960 | release_console_sem(); | |
961 | } | |
962 | ||
1da177e4 LT |
963 | /** |
964 | * acquire_console_sem - lock the console system for exclusive use. | |
965 | * | |
966 | * Acquires a semaphore which guarantees that the caller has | |
967 | * exclusive access to the console system and the console_drivers list. | |
968 | * | |
969 | * Can sleep, returns nothing. | |
970 | */ | |
971 | void acquire_console_sem(void) | |
972 | { | |
8abd8e29 | 973 | BUG_ON(in_interrupt()); |
1da177e4 | 974 | down(&console_sem); |
403f3075 AH |
975 | if (console_suspended) |
976 | return; | |
1da177e4 LT |
977 | console_locked = 1; |
978 | console_may_schedule = 1; | |
979 | } | |
980 | EXPORT_SYMBOL(acquire_console_sem); | |
981 | ||
982 | int try_acquire_console_sem(void) | |
983 | { | |
984 | if (down_trylock(&console_sem)) | |
985 | return -1; | |
403f3075 AH |
986 | if (console_suspended) { |
987 | up(&console_sem); | |
988 | return -1; | |
989 | } | |
1da177e4 LT |
990 | console_locked = 1; |
991 | console_may_schedule = 0; | |
992 | return 0; | |
993 | } | |
994 | EXPORT_SYMBOL(try_acquire_console_sem); | |
995 | ||
996 | int is_console_locked(void) | |
997 | { | |
998 | return console_locked; | |
999 | } | |
1da177e4 | 1000 | |
b845b517 PZ |
1001 | static DEFINE_PER_CPU(int, printk_pending); |
1002 | ||
1003 | void printk_tick(void) | |
e3e8a75d | 1004 | { |
b845b517 PZ |
1005 | if (__get_cpu_var(printk_pending)) { |
1006 | __get_cpu_var(printk_pending) = 0; | |
e3e8a75d | 1007 | wake_up_interruptible(&log_wait); |
b845b517 PZ |
1008 | } |
1009 | } | |
1010 | ||
1011 | int printk_needs_cpu(int cpu) | |
1012 | { | |
1013 | return per_cpu(printk_pending, cpu); | |
1014 | } | |
1015 | ||
1016 | void wake_up_klogd(void) | |
1017 | { | |
1018 | if (waitqueue_active(&log_wait)) | |
fa33507a | 1019 | __raw_get_cpu_var(printk_pending) = 1; |
e3e8a75d KK |
1020 | } |
1021 | ||
1da177e4 LT |
1022 | /** |
1023 | * release_console_sem - unlock the console system | |
1024 | * | |
1025 | * Releases the semaphore which the caller holds on the console system | |
1026 | * and the console driver list. | |
1027 | * | |
1028 | * While the semaphore was held, console output may have been buffered | |
1029 | * by printk(). If this is the case, release_console_sem() emits | |
1030 | * the output prior to releasing the semaphore. | |
1031 | * | |
1032 | * If there is output waiting for klogd, we wake it up. | |
1033 | * | |
1034 | * release_console_sem() may be called from any context. | |
1035 | */ | |
1036 | void release_console_sem(void) | |
1037 | { | |
1038 | unsigned long flags; | |
eed4a2ab DV |
1039 | unsigned _con_start, _log_end; |
1040 | unsigned wake_klogd = 0; | |
1da177e4 | 1041 | |
557240b4 | 1042 | if (console_suspended) { |
403f3075 | 1043 | up(&console_sem); |
557240b4 LT |
1044 | return; |
1045 | } | |
78944e54 AD |
1046 | |
1047 | console_may_schedule = 0; | |
1048 | ||
1da177e4 LT |
1049 | for ( ; ; ) { |
1050 | spin_lock_irqsave(&logbuf_lock, flags); | |
1051 | wake_klogd |= log_start - log_end; | |
1052 | if (con_start == log_end) | |
1053 | break; /* Nothing to print */ | |
1054 | _con_start = con_start; | |
1055 | _log_end = log_end; | |
1056 | con_start = log_end; /* Flush */ | |
1057 | spin_unlock(&logbuf_lock); | |
81d68a96 | 1058 | stop_critical_timings(); /* don't trace print latency */ |
1da177e4 | 1059 | call_console_drivers(_con_start, _log_end); |
81d68a96 | 1060 | start_critical_timings(); |
1da177e4 LT |
1061 | local_irq_restore(flags); |
1062 | } | |
1063 | console_locked = 0; | |
1da177e4 LT |
1064 | up(&console_sem); |
1065 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
1066 | if (wake_klogd) |
1067 | wake_up_klogd(); | |
1da177e4 LT |
1068 | } |
1069 | EXPORT_SYMBOL(release_console_sem); | |
1070 | ||
ddad86c2 MW |
1071 | /** |
1072 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1073 | * |
1074 | * If the console code is currently allowed to sleep, and | |
1075 | * if this CPU should yield the CPU to another task, do | |
1076 | * so here. | |
1077 | * | |
1078 | * Must be called within acquire_console_sem(). | |
1079 | */ | |
1080 | void __sched console_conditional_schedule(void) | |
1081 | { | |
1082 | if (console_may_schedule) | |
1083 | cond_resched(); | |
1084 | } | |
1085 | EXPORT_SYMBOL(console_conditional_schedule); | |
1086 | ||
1da177e4 LT |
1087 | void console_unblank(void) |
1088 | { | |
1089 | struct console *c; | |
1090 | ||
1091 | /* | |
1092 | * console_unblank can no longer be called in interrupt context unless | |
1093 | * oops_in_progress is set to 1.. | |
1094 | */ | |
1095 | if (oops_in_progress) { | |
1096 | if (down_trylock(&console_sem) != 0) | |
1097 | return; | |
1098 | } else | |
1099 | acquire_console_sem(); | |
1100 | ||
1101 | console_locked = 1; | |
1102 | console_may_schedule = 0; | |
4d091611 | 1103 | for_each_console(c) |
1da177e4 LT |
1104 | if ((c->flags & CON_ENABLED) && c->unblank) |
1105 | c->unblank(); | |
1106 | release_console_sem(); | |
1107 | } | |
1da177e4 LT |
1108 | |
1109 | /* | |
1110 | * Return the console tty driver structure and its associated index | |
1111 | */ | |
1112 | struct tty_driver *console_device(int *index) | |
1113 | { | |
1114 | struct console *c; | |
1115 | struct tty_driver *driver = NULL; | |
1116 | ||
1117 | acquire_console_sem(); | |
4d091611 | 1118 | for_each_console(c) { |
1da177e4 LT |
1119 | if (!c->device) |
1120 | continue; | |
1121 | driver = c->device(c, index); | |
1122 | if (driver) | |
1123 | break; | |
1124 | } | |
1125 | release_console_sem(); | |
1126 | return driver; | |
1127 | } | |
1128 | ||
1129 | /* | |
1130 | * Prevent further output on the passed console device so that (for example) | |
1131 | * serial drivers can disable console output before suspending a port, and can | |
1132 | * re-enable output afterwards. | |
1133 | */ | |
1134 | void console_stop(struct console *console) | |
1135 | { | |
1136 | acquire_console_sem(); | |
1137 | console->flags &= ~CON_ENABLED; | |
1138 | release_console_sem(); | |
1139 | } | |
1140 | EXPORT_SYMBOL(console_stop); | |
1141 | ||
1142 | void console_start(struct console *console) | |
1143 | { | |
1144 | acquire_console_sem(); | |
1145 | console->flags |= CON_ENABLED; | |
1146 | release_console_sem(); | |
1147 | } | |
1148 | EXPORT_SYMBOL(console_start); | |
1149 | ||
1150 | /* | |
1151 | * The console driver calls this routine during kernel initialization | |
1152 | * to register the console printing procedure with printk() and to | |
1153 | * print any messages that were printed by the kernel before the | |
1154 | * console driver was initialized. | |
4d091611 RG |
1155 | * |
1156 | * This can happen pretty early during the boot process (because of | |
1157 | * early_printk) - sometimes before setup_arch() completes - be careful | |
1158 | * of what kernel features are used - they may not be initialised yet. | |
1159 | * | |
1160 | * There are two types of consoles - bootconsoles (early_printk) and | |
1161 | * "real" consoles (everything which is not a bootconsole) which are | |
1162 | * handled differently. | |
1163 | * - Any number of bootconsoles can be registered at any time. | |
1164 | * - As soon as a "real" console is registered, all bootconsoles | |
1165 | * will be unregistered automatically. | |
1166 | * - Once a "real" console is registered, any attempt to register a | |
1167 | * bootconsoles will be rejected | |
1da177e4 | 1168 | */ |
4d091611 | 1169 | void register_console(struct console *newcon) |
1da177e4 | 1170 | { |
40dc5651 | 1171 | int i; |
1da177e4 | 1172 | unsigned long flags; |
4d091611 | 1173 | struct console *bcon = NULL; |
1da177e4 | 1174 | |
4d091611 RG |
1175 | /* |
1176 | * before we register a new CON_BOOT console, make sure we don't | |
1177 | * already have a valid console | |
1178 | */ | |
1179 | if (console_drivers && newcon->flags & CON_BOOT) { | |
1180 | /* find the last or real console */ | |
1181 | for_each_console(bcon) { | |
1182 | if (!(bcon->flags & CON_BOOT)) { | |
1183 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", | |
1184 | newcon->name, newcon->index); | |
1185 | return; | |
1186 | } | |
1187 | } | |
69331af7 GH |
1188 | } |
1189 | ||
4d091611 RG |
1190 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1191 | bcon = console_drivers; | |
1192 | ||
1193 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
1194 | preferred_console = selected_console; |
1195 | ||
4d091611 RG |
1196 | if (newcon->early_setup) |
1197 | newcon->early_setup(); | |
18a8bd94 | 1198 | |
1da177e4 LT |
1199 | /* |
1200 | * See if we want to use this console driver. If we | |
1201 | * didn't select a console we take the first one | |
1202 | * that registers here. | |
1203 | */ | |
1204 | if (preferred_console < 0) { | |
4d091611 RG |
1205 | if (newcon->index < 0) |
1206 | newcon->index = 0; | |
1207 | if (newcon->setup == NULL || | |
1208 | newcon->setup(newcon, NULL) == 0) { | |
1209 | newcon->flags |= CON_ENABLED; | |
1210 | if (newcon->device) { | |
1211 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
1212 | preferred_console = 0; |
1213 | } | |
1da177e4 LT |
1214 | } |
1215 | } | |
1216 | ||
1217 | /* | |
1218 | * See if this console matches one we selected on | |
1219 | * the command line. | |
1220 | */ | |
40dc5651 JJ |
1221 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1222 | i++) { | |
4d091611 | 1223 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1da177e4 | 1224 | continue; |
4d091611 RG |
1225 | if (newcon->index >= 0 && |
1226 | newcon->index != console_cmdline[i].index) | |
1da177e4 | 1227 | continue; |
4d091611 RG |
1228 | if (newcon->index < 0) |
1229 | newcon->index = console_cmdline[i].index; | |
f7511d5f ST |
1230 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1231 | if (console_cmdline[i].brl_options) { | |
4d091611 RG |
1232 | newcon->flags |= CON_BRL; |
1233 | braille_register_console(newcon, | |
f7511d5f ST |
1234 | console_cmdline[i].index, |
1235 | console_cmdline[i].options, | |
1236 | console_cmdline[i].brl_options); | |
1237 | return; | |
1238 | } | |
1239 | #endif | |
4d091611 RG |
1240 | if (newcon->setup && |
1241 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 1242 | break; |
4d091611 RG |
1243 | newcon->flags |= CON_ENABLED; |
1244 | newcon->index = console_cmdline[i].index; | |
ab4af03a | 1245 | if (i == selected_console) { |
4d091611 | 1246 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
1247 | preferred_console = selected_console; |
1248 | } | |
1da177e4 LT |
1249 | break; |
1250 | } | |
1251 | ||
4d091611 | 1252 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
1253 | return; |
1254 | ||
8259cf43 RG |
1255 | /* |
1256 | * If we have a bootconsole, and are switching to a real console, | |
1257 | * don't print everything out again, since when the boot console, and | |
1258 | * the real console are the same physical device, it's annoying to | |
1259 | * see the beginning boot messages twice | |
1260 | */ | |
1261 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 1262 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
1263 | |
1264 | /* | |
1265 | * Put this console in the list - keep the | |
1266 | * preferred driver at the head of the list. | |
1267 | */ | |
1268 | acquire_console_sem(); | |
4d091611 RG |
1269 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1270 | newcon->next = console_drivers; | |
1271 | console_drivers = newcon; | |
1272 | if (newcon->next) | |
1273 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 1274 | } else { |
4d091611 RG |
1275 | newcon->next = console_drivers->next; |
1276 | console_drivers->next = newcon; | |
1da177e4 | 1277 | } |
4d091611 | 1278 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 LT |
1279 | /* |
1280 | * release_console_sem() will print out the buffered messages | |
1281 | * for us. | |
1282 | */ | |
1283 | spin_lock_irqsave(&logbuf_lock, flags); | |
1284 | con_start = log_start; | |
1285 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1286 | } | |
1287 | release_console_sem(); | |
8259cf43 RG |
1288 | |
1289 | /* | |
1290 | * By unregistering the bootconsoles after we enable the real console | |
1291 | * we get the "console xxx enabled" message on all the consoles - | |
1292 | * boot consoles, real consoles, etc - this is to ensure that end | |
1293 | * users know there might be something in the kernel's log buffer that | |
1294 | * went to the bootconsole (that they do not see on the real console) | |
1295 | */ | |
1296 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) { | |
1297 | /* we need to iterate through twice, to make sure we print | |
1298 | * everything out, before we unregister the console(s) | |
1299 | */ | |
1300 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", | |
1301 | newcon->name, newcon->index); | |
1302 | for_each_console(bcon) | |
1303 | if (bcon->flags & CON_BOOT) | |
1304 | unregister_console(bcon); | |
1305 | } else { | |
1306 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", | |
1307 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
1308 | newcon->name, newcon->index); | |
1309 | } | |
1da177e4 LT |
1310 | } |
1311 | EXPORT_SYMBOL(register_console); | |
1312 | ||
40dc5651 | 1313 | int unregister_console(struct console *console) |
1da177e4 | 1314 | { |
40dc5651 | 1315 | struct console *a, *b; |
1da177e4 LT |
1316 | int res = 1; |
1317 | ||
f7511d5f ST |
1318 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1319 | if (console->flags & CON_BRL) | |
1320 | return braille_unregister_console(console); | |
1321 | #endif | |
1322 | ||
1da177e4 LT |
1323 | acquire_console_sem(); |
1324 | if (console_drivers == console) { | |
1325 | console_drivers=console->next; | |
1326 | res = 0; | |
e9b15b54 | 1327 | } else if (console_drivers) { |
1da177e4 LT |
1328 | for (a=console_drivers->next, b=console_drivers ; |
1329 | a; b=a, a=b->next) { | |
1330 | if (a == console) { | |
1331 | b->next = a->next; | |
1332 | res = 0; | |
1333 | break; | |
40dc5651 | 1334 | } |
1da177e4 LT |
1335 | } |
1336 | } | |
40dc5651 | 1337 | |
69331af7 | 1338 | /* |
ab4af03a GE |
1339 | * If this isn't the last console and it has CON_CONSDEV set, we |
1340 | * need to set it on the next preferred console. | |
1da177e4 | 1341 | */ |
69331af7 | 1342 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1343 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 LT |
1344 | |
1345 | release_console_sem(); | |
1346 | return res; | |
1347 | } | |
1348 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1349 | |
0c5564bd RG |
1350 | static int __init disable_boot_consoles(void) |
1351 | { | |
4d091611 RG |
1352 | struct console *con; |
1353 | ||
1354 | for_each_console(con) { | |
1355 | if (con->flags & CON_BOOT) { | |
cb00e99c | 1356 | printk(KERN_INFO "turn off boot console %s%d\n", |
4d091611 | 1357 | con->name, con->index); |
42c2c8c8 | 1358 | unregister_console(con); |
cb00e99c | 1359 | } |
0c5564bd RG |
1360 | } |
1361 | return 0; | |
1362 | } | |
1363 | late_initcall(disable_boot_consoles); | |
1364 | ||
7ef3d2fd | 1365 | #if defined CONFIG_PRINTK |
717115e1 | 1366 | |
1da177e4 LT |
1367 | /* |
1368 | * printk rate limiting, lifted from the networking subsystem. | |
1369 | * | |
641de9d8 UKK |
1370 | * This enforces a rate limit: not more than 10 kernel messages |
1371 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 1372 | */ |
641de9d8 UKK |
1373 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1374 | ||
5c828713 | 1375 | int __printk_ratelimit(const char *func) |
1da177e4 | 1376 | { |
5c828713 | 1377 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 1378 | } |
5c828713 | 1379 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
1380 | |
1381 | /** | |
1382 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1383 | * @caller_jiffies: pointer to caller's state | |
1384 | * @interval_msecs: minimum interval between prints | |
1385 | * | |
1386 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1387 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1388 | * returned true. | |
1389 | */ | |
1390 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1391 | unsigned int interval_msecs) | |
1392 | { | |
f2d28a2e GK |
1393 | if (*caller_jiffies == 0 |
1394 | || !time_in_range(jiffies, *caller_jiffies, | |
1395 | *caller_jiffies | |
1396 | + msecs_to_jiffies(interval_msecs))) { | |
1397 | *caller_jiffies = jiffies; | |
f46c4833 AM |
1398 | return true; |
1399 | } | |
1400 | return false; | |
1401 | } | |
1402 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
1403 | |
1404 | static DEFINE_SPINLOCK(dump_list_lock); | |
1405 | static LIST_HEAD(dump_list); | |
1406 | ||
1407 | /** | |
1408 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 1409 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1410 | * |
1411 | * Adds a kernel log dumper to the system. The dump callback in the | |
1412 | * structure will be called when the kernel oopses or panics and must be | |
1413 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
1414 | */ | |
1415 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
1416 | { | |
1417 | unsigned long flags; | |
1418 | int err = -EBUSY; | |
1419 | ||
1420 | /* The dump callback needs to be set */ | |
1421 | if (!dumper->dump) | |
1422 | return -EINVAL; | |
1423 | ||
1424 | spin_lock_irqsave(&dump_list_lock, flags); | |
1425 | /* Don't allow registering multiple times */ | |
1426 | if (!dumper->registered) { | |
1427 | dumper->registered = 1; | |
1428 | list_add_tail(&dumper->list, &dump_list); | |
1429 | err = 0; | |
1430 | } | |
1431 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1432 | ||
1433 | return err; | |
1434 | } | |
1435 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
1436 | ||
1437 | /** | |
1438 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 1439 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1440 | * |
1441 | * Removes a dump device from the system. Returns zero on success and | |
1442 | * %-EINVAL otherwise. | |
1443 | */ | |
1444 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
1445 | { | |
1446 | unsigned long flags; | |
1447 | int err = -EINVAL; | |
1448 | ||
1449 | spin_lock_irqsave(&dump_list_lock, flags); | |
1450 | if (dumper->registered) { | |
1451 | dumper->registered = 0; | |
1452 | list_del(&dumper->list); | |
1453 | err = 0; | |
1454 | } | |
1455 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1456 | ||
1457 | return err; | |
1458 | } | |
1459 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
1460 | ||
1461 | static const char const *kmsg_reasons[] = { | |
1462 | [KMSG_DUMP_OOPS] = "oops", | |
1463 | [KMSG_DUMP_PANIC] = "panic", | |
0f4bd46e | 1464 | [KMSG_DUMP_KEXEC] = "kexec", |
456b565c SK |
1465 | }; |
1466 | ||
1467 | static const char *kmsg_to_str(enum kmsg_dump_reason reason) | |
1468 | { | |
1469 | if (reason >= ARRAY_SIZE(kmsg_reasons) || reason < 0) | |
1470 | return "unknown"; | |
1471 | ||
1472 | return kmsg_reasons[reason]; | |
1473 | } | |
1474 | ||
1475 | /** | |
1476 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
1477 | * @reason: the reason (oops, panic etc) for dumping | |
1478 | * | |
1479 | * Iterate through each of the dump devices and call the oops/panic | |
1480 | * callbacks with the log buffer. | |
1481 | */ | |
1482 | void kmsg_dump(enum kmsg_dump_reason reason) | |
1483 | { | |
1484 | unsigned long end; | |
1485 | unsigned chars; | |
1486 | struct kmsg_dumper *dumper; | |
1487 | const char *s1, *s2; | |
1488 | unsigned long l1, l2; | |
1489 | unsigned long flags; | |
1490 | ||
1491 | /* Theoretically, the log could move on after we do this, but | |
1492 | there's not a lot we can do about that. The new messages | |
1493 | will overwrite the start of what we dump. */ | |
1494 | spin_lock_irqsave(&logbuf_lock, flags); | |
1495 | end = log_end & LOG_BUF_MASK; | |
1496 | chars = logged_chars; | |
1497 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1498 | ||
1499 | if (logged_chars > end) { | |
1500 | s1 = log_buf + log_buf_len - logged_chars + end; | |
1501 | l1 = logged_chars - end; | |
1502 | ||
1503 | s2 = log_buf; | |
1504 | l2 = end; | |
1505 | } else { | |
1506 | s1 = ""; | |
1507 | l1 = 0; | |
1508 | ||
1509 | s2 = log_buf + end - logged_chars; | |
1510 | l2 = logged_chars; | |
1511 | } | |
1512 | ||
1513 | if (!spin_trylock_irqsave(&dump_list_lock, flags)) { | |
1514 | printk(KERN_ERR "dump_kmsg: dump list lock is held during %s, skipping dump\n", | |
1515 | kmsg_to_str(reason)); | |
1516 | return; | |
1517 | } | |
1518 | list_for_each_entry(dumper, &dump_list, list) | |
1519 | dumper->dump(dumper, reason, s1, l1, s2, l2); | |
1520 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1521 | } | |
7ef3d2fd | 1522 | #endif |