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> | |
162a7e75 | 34 | #include <linux/memblock.h> |
1da177e4 | 35 | #include <linux/syscalls.h> |
04d491ab | 36 | #include <linux/kexec.h> |
d37d39ae | 37 | #include <linux/kdb.h> |
3fff4c42 | 38 | #include <linux/ratelimit.h> |
456b565c | 39 | #include <linux/kmsg_dump.h> |
00234592 | 40 | #include <linux/syslog.h> |
034260d6 KC |
41 | #include <linux/cpu.h> |
42 | #include <linux/notifier.h> | |
fb842b00 | 43 | #include <linux/rculist.h> |
1da177e4 LT |
44 | |
45 | #include <asm/uaccess.h> | |
46 | ||
95100358 JB |
47 | #define CREATE_TRACE_POINTS |
48 | #include <trace/events/printk.h> | |
49 | ||
076f9776 IM |
50 | /* |
51 | * Architectures can override it: | |
52 | */ | |
e17ba73b | 53 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
076f9776 IM |
54 | { |
55 | } | |
56 | ||
1da177e4 LT |
57 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
58 | ||
59 | /* printk's without a loglevel use this.. */ | |
5af5bcb8 | 60 | #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL |
1da177e4 LT |
61 | |
62 | /* We show everything that is MORE important than this.. */ | |
63 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
64 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
65 | ||
66 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
67 | ||
68 | int console_printk[4] = { | |
69 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
70 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
71 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
72 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
73 | }; | |
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 | */ | |
5b8c4f23 | 87 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 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 | |
ac751efa | 104 | * console_unlock();. |
1da177e4 | 105 | */ |
07354eb1 | 106 | static DEFINE_RAW_SPINLOCK(logbuf_lock); |
1da177e4 | 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 | 118 | |
fe3d8ad3 FT |
119 | /* |
120 | * If exclusive_console is non-NULL then only this console is to be printed to. | |
121 | */ | |
122 | static struct console *exclusive_console; | |
123 | ||
1da177e4 LT |
124 | /* |
125 | * Array of consoles built from command line options (console=) | |
126 | */ | |
127 | struct console_cmdline | |
128 | { | |
129 | char name[8]; /* Name of the driver */ | |
130 | int index; /* Minor dev. to use */ | |
131 | char *options; /* Options for the driver */ | |
f7511d5f ST |
132 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
133 | char *brl_options; /* Options for braille driver */ | |
134 | #endif | |
1da177e4 LT |
135 | }; |
136 | ||
137 | #define MAX_CMDLINECONSOLES 8 | |
138 | ||
139 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
140 | static int selected_console = -1; | |
141 | static int preferred_console = -1; | |
9e124fe1 MA |
142 | int console_set_on_cmdline; |
143 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
144 | |
145 | /* Flag: console code may call schedule() */ | |
146 | static int console_may_schedule; | |
147 | ||
d59745ce MM |
148 | #ifdef CONFIG_PRINTK |
149 | ||
150 | static char __log_buf[__LOG_BUF_LEN]; | |
151 | static char *log_buf = __log_buf; | |
152 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 153 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
cea83886 | 154 | static int saved_console_loglevel = -1; |
d59745ce | 155 | |
04d491ab NH |
156 | #ifdef CONFIG_KEXEC |
157 | /* | |
158 | * This appends the listed symbols to /proc/vmcoreinfo | |
159 | * | |
160 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
161 | * obtain access to symbols that are otherwise very difficult to locate. These | |
162 | * symbols are specifically used so that utilities can access and extract the | |
163 | * dmesg log from a vmcore file after a crash. | |
164 | */ | |
165 | void log_buf_kexec_setup(void) | |
166 | { | |
167 | VMCOREINFO_SYMBOL(log_buf); | |
168 | VMCOREINFO_SYMBOL(log_end); | |
169 | VMCOREINFO_SYMBOL(log_buf_len); | |
170 | VMCOREINFO_SYMBOL(logged_chars); | |
171 | } | |
172 | #endif | |
173 | ||
162a7e75 MT |
174 | /* requested log_buf_len from kernel cmdline */ |
175 | static unsigned long __initdata new_log_buf_len; | |
176 | ||
177 | /* save requested log_buf_len since it's too early to process it */ | |
1da177e4 LT |
178 | static int __init log_buf_len_setup(char *str) |
179 | { | |
eed4a2ab | 180 | unsigned size = memparse(str, &str); |
1da177e4 LT |
181 | |
182 | if (size) | |
183 | size = roundup_pow_of_two(size); | |
162a7e75 MT |
184 | if (size > log_buf_len) |
185 | new_log_buf_len = size; | |
186 | ||
187 | return 0; | |
1da177e4 | 188 | } |
162a7e75 MT |
189 | early_param("log_buf_len", log_buf_len_setup); |
190 | ||
191 | void __init setup_log_buf(int early) | |
192 | { | |
193 | unsigned long flags; | |
194 | unsigned start, dest_idx, offset; | |
195 | char *new_log_buf; | |
196 | int free; | |
197 | ||
198 | if (!new_log_buf_len) | |
199 | return; | |
1da177e4 | 200 | |
162a7e75 MT |
201 | if (early) { |
202 | unsigned long mem; | |
203 | ||
204 | mem = memblock_alloc(new_log_buf_len, PAGE_SIZE); | |
1f5026a7 | 205 | if (!mem) |
162a7e75 MT |
206 | return; |
207 | new_log_buf = __va(mem); | |
208 | } else { | |
209 | new_log_buf = alloc_bootmem_nopanic(new_log_buf_len); | |
210 | } | |
211 | ||
212 | if (unlikely(!new_log_buf)) { | |
213 | pr_err("log_buf_len: %ld bytes not available\n", | |
214 | new_log_buf_len); | |
215 | return; | |
216 | } | |
217 | ||
07354eb1 | 218 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
162a7e75 MT |
219 | log_buf_len = new_log_buf_len; |
220 | log_buf = new_log_buf; | |
221 | new_log_buf_len = 0; | |
222 | free = __LOG_BUF_LEN - log_end; | |
223 | ||
224 | offset = start = min(con_start, log_start); | |
225 | dest_idx = 0; | |
226 | while (start != log_end) { | |
227 | unsigned log_idx_mask = start & (__LOG_BUF_LEN - 1); | |
228 | ||
229 | log_buf[dest_idx] = __log_buf[log_idx_mask]; | |
230 | start++; | |
231 | dest_idx++; | |
232 | } | |
233 | log_start -= offset; | |
234 | con_start -= offset; | |
235 | log_end -= offset; | |
07354eb1 | 236 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
162a7e75 MT |
237 | |
238 | pr_info("log_buf_len: %d\n", log_buf_len); | |
239 | pr_info("early log buf free: %d(%d%%)\n", | |
240 | free, (free * 100) / __LOG_BUF_LEN); | |
241 | } | |
1da177e4 | 242 | |
bfe8df3d RD |
243 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
244 | ||
674dff65 | 245 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 246 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
247 | |
248 | static int __init boot_delay_setup(char *str) | |
249 | { | |
250 | unsigned long lpj; | |
bfe8df3d RD |
251 | |
252 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
253 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
254 | ||
255 | get_option(&str, &boot_delay); | |
256 | if (boot_delay > 10 * 1000) | |
257 | boot_delay = 0; | |
258 | ||
3a3b6ed2 DY |
259 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
260 | "HZ: %d, loops_per_msec: %llu\n", | |
261 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
bfe8df3d RD |
262 | return 1; |
263 | } | |
264 | __setup("boot_delay=", boot_delay_setup); | |
265 | ||
266 | static void boot_delay_msec(void) | |
267 | { | |
268 | unsigned long long k; | |
269 | unsigned long timeout; | |
270 | ||
271 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
272 | return; | |
273 | ||
3a3b6ed2 | 274 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
275 | |
276 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
277 | while (k) { | |
278 | k--; | |
279 | cpu_relax(); | |
280 | /* | |
281 | * use (volatile) jiffies to prevent | |
282 | * compiler reduction; loop termination via jiffies | |
283 | * is secondary and may or may not happen. | |
284 | */ | |
285 | if (time_after(jiffies, timeout)) | |
286 | break; | |
287 | touch_nmi_watchdog(); | |
288 | } | |
289 | } | |
290 | #else | |
291 | static inline void boot_delay_msec(void) | |
292 | { | |
293 | } | |
294 | #endif | |
295 | ||
eaf06b24 DR |
296 | #ifdef CONFIG_SECURITY_DMESG_RESTRICT |
297 | int dmesg_restrict = 1; | |
298 | #else | |
299 | int dmesg_restrict; | |
300 | #endif | |
301 | ||
ee24aebf LT |
302 | static int syslog_action_restricted(int type) |
303 | { | |
304 | if (dmesg_restrict) | |
305 | return 1; | |
306 | /* Unless restricted, we allow "read all" and "get buffer size" for everybody */ | |
307 | return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; | |
308 | } | |
309 | ||
310 | static int check_syslog_permissions(int type, bool from_file) | |
311 | { | |
312 | /* | |
313 | * If this is from /proc/kmsg and we've already opened it, then we've | |
314 | * already done the capabilities checks at open time. | |
315 | */ | |
316 | if (from_file && type != SYSLOG_ACTION_OPEN) | |
317 | return 0; | |
318 | ||
319 | if (syslog_action_restricted(type)) { | |
320 | if (capable(CAP_SYSLOG)) | |
321 | return 0; | |
322 | /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */ | |
323 | if (capable(CAP_SYS_ADMIN)) { | |
f2c0d026 JN |
324 | printk_once(KERN_WARNING "%s (%d): " |
325 | "Attempt to access syslog with CAP_SYS_ADMIN " | |
326 | "but no CAP_SYSLOG (deprecated).\n", | |
327 | current->comm, task_pid_nr(current)); | |
ee24aebf LT |
328 | return 0; |
329 | } | |
330 | return -EPERM; | |
331 | } | |
332 | return 0; | |
333 | } | |
334 | ||
00234592 | 335 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
1da177e4 | 336 | { |
eed4a2ab | 337 | unsigned i, j, limit, count; |
1da177e4 LT |
338 | int do_clear = 0; |
339 | char c; | |
ee24aebf | 340 | int error; |
1da177e4 | 341 | |
ee24aebf LT |
342 | error = check_syslog_permissions(type, from_file); |
343 | if (error) | |
344 | goto out; | |
12b3052c EP |
345 | |
346 | error = security_syslog(type); | |
1da177e4 LT |
347 | if (error) |
348 | return error; | |
349 | ||
350 | switch (type) { | |
d78ca3cd | 351 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 352 | break; |
d78ca3cd | 353 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 354 | break; |
d78ca3cd | 355 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 LT |
356 | error = -EINVAL; |
357 | if (!buf || len < 0) | |
358 | goto out; | |
359 | error = 0; | |
360 | if (!len) | |
361 | goto out; | |
362 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
363 | error = -EFAULT; | |
364 | goto out; | |
365 | } | |
40dc5651 JJ |
366 | error = wait_event_interruptible(log_wait, |
367 | (log_start - log_end)); | |
1da177e4 LT |
368 | if (error) |
369 | goto out; | |
370 | i = 0; | |
07354eb1 | 371 | raw_spin_lock_irq(&logbuf_lock); |
1da177e4 LT |
372 | while (!error && (log_start != log_end) && i < len) { |
373 | c = LOG_BUF(log_start); | |
374 | log_start++; | |
07354eb1 | 375 | raw_spin_unlock_irq(&logbuf_lock); |
1da177e4 LT |
376 | error = __put_user(c,buf); |
377 | buf++; | |
378 | i++; | |
379 | cond_resched(); | |
07354eb1 | 380 | raw_spin_lock_irq(&logbuf_lock); |
1da177e4 | 381 | } |
07354eb1 | 382 | raw_spin_unlock_irq(&logbuf_lock); |
1da177e4 LT |
383 | if (!error) |
384 | error = i; | |
385 | break; | |
d78ca3cd KC |
386 | /* Read/clear last kernel messages */ |
387 | case SYSLOG_ACTION_READ_CLEAR: | |
40dc5651 | 388 | do_clear = 1; |
1da177e4 | 389 | /* FALL THRU */ |
d78ca3cd KC |
390 | /* Read last kernel messages */ |
391 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 LT |
392 | error = -EINVAL; |
393 | if (!buf || len < 0) | |
394 | goto out; | |
395 | error = 0; | |
396 | if (!len) | |
397 | goto out; | |
398 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
399 | error = -EFAULT; | |
400 | goto out; | |
401 | } | |
402 | count = len; | |
403 | if (count > log_buf_len) | |
404 | count = log_buf_len; | |
07354eb1 | 405 | raw_spin_lock_irq(&logbuf_lock); |
1da177e4 LT |
406 | if (count > logged_chars) |
407 | count = logged_chars; | |
408 | if (do_clear) | |
409 | logged_chars = 0; | |
410 | limit = log_end; | |
411 | /* | |
412 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 413 | * printk() could overwrite the messages |
1da177e4 LT |
414 | * we try to copy to user space. Therefore |
415 | * the messages are copied in reverse. <manfreds> | |
416 | */ | |
40dc5651 | 417 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
418 | j = limit-1-i; |
419 | if (j + log_buf_len < log_end) | |
420 | break; | |
421 | c = LOG_BUF(j); | |
07354eb1 | 422 | raw_spin_unlock_irq(&logbuf_lock); |
1da177e4 LT |
423 | error = __put_user(c,&buf[count-1-i]); |
424 | cond_resched(); | |
07354eb1 | 425 | raw_spin_lock_irq(&logbuf_lock); |
1da177e4 | 426 | } |
07354eb1 | 427 | raw_spin_unlock_irq(&logbuf_lock); |
1da177e4 LT |
428 | if (error) |
429 | break; | |
430 | error = i; | |
40dc5651 | 431 | if (i != count) { |
1da177e4 LT |
432 | int offset = count-error; |
433 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 434 | for (i = 0; i < error; i++) { |
1da177e4 LT |
435 | if (__get_user(c,&buf[i+offset]) || |
436 | __put_user(c,&buf[i])) { | |
437 | error = -EFAULT; | |
438 | break; | |
439 | } | |
440 | cond_resched(); | |
441 | } | |
442 | } | |
443 | break; | |
d78ca3cd KC |
444 | /* Clear ring buffer */ |
445 | case SYSLOG_ACTION_CLEAR: | |
1da177e4 LT |
446 | logged_chars = 0; |
447 | break; | |
d78ca3cd KC |
448 | /* Disable logging to console */ |
449 | case SYSLOG_ACTION_CONSOLE_OFF: | |
1aaad49e FP |
450 | if (saved_console_loglevel == -1) |
451 | saved_console_loglevel = console_loglevel; | |
1da177e4 LT |
452 | console_loglevel = minimum_console_loglevel; |
453 | break; | |
d78ca3cd KC |
454 | /* Enable logging to console */ |
455 | case SYSLOG_ACTION_CONSOLE_ON: | |
1aaad49e FP |
456 | if (saved_console_loglevel != -1) { |
457 | console_loglevel = saved_console_loglevel; | |
458 | saved_console_loglevel = -1; | |
459 | } | |
1da177e4 | 460 | break; |
d78ca3cd KC |
461 | /* Set level of messages printed to console */ |
462 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 LT |
463 | error = -EINVAL; |
464 | if (len < 1 || len > 8) | |
465 | goto out; | |
466 | if (len < minimum_console_loglevel) | |
467 | len = minimum_console_loglevel; | |
468 | console_loglevel = len; | |
1aaad49e FP |
469 | /* Implicitly re-enable logging to console */ |
470 | saved_console_loglevel = -1; | |
1da177e4 LT |
471 | error = 0; |
472 | break; | |
d78ca3cd KC |
473 | /* Number of chars in the log buffer */ |
474 | case SYSLOG_ACTION_SIZE_UNREAD: | |
1da177e4 LT |
475 | error = log_end - log_start; |
476 | break; | |
d78ca3cd KC |
477 | /* Size of the log buffer */ |
478 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
479 | error = log_buf_len; |
480 | break; | |
481 | default: | |
482 | error = -EINVAL; | |
483 | break; | |
484 | } | |
485 | out: | |
486 | return error; | |
487 | } | |
488 | ||
1e7bfb21 | 489 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 490 | { |
00234592 | 491 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
1da177e4 LT |
492 | } |
493 | ||
67fc4e0c JW |
494 | #ifdef CONFIG_KGDB_KDB |
495 | /* kdb dmesg command needs access to the syslog buffer. do_syslog() | |
496 | * uses locks so it cannot be used during debugging. Just tell kdb | |
497 | * where the start and end of the physical and logical logs are. This | |
498 | * is equivalent to do_syslog(3). | |
499 | */ | |
500 | void kdb_syslog_data(char *syslog_data[4]) | |
501 | { | |
502 | syslog_data[0] = log_buf; | |
503 | syslog_data[1] = log_buf + log_buf_len; | |
504 | syslog_data[2] = log_buf + log_end - | |
505 | (logged_chars < log_buf_len ? logged_chars : log_buf_len); | |
506 | syslog_data[3] = log_buf + log_end; | |
507 | } | |
508 | #endif /* CONFIG_KGDB_KDB */ | |
509 | ||
1da177e4 LT |
510 | /* |
511 | * Call the console drivers on a range of log_buf | |
512 | */ | |
eed4a2ab | 513 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
514 | { |
515 | struct console *con; | |
516 | ||
4d091611 | 517 | for_each_console(con) { |
fe3d8ad3 FT |
518 | if (exclusive_console && con != exclusive_console) |
519 | continue; | |
76a8ad29 ME |
520 | if ((con->flags & CON_ENABLED) && con->write && |
521 | (cpu_online(smp_processor_id()) || | |
522 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
523 | con->write(con, &LOG_BUF(start), end - start); |
524 | } | |
525 | } | |
526 | ||
2329abfa | 527 | static bool __read_mostly ignore_loglevel; |
79290822 | 528 | |
99eea6a1 | 529 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
530 | { |
531 | ignore_loglevel = 1; | |
532 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
533 | ||
c4772d99 | 534 | return 0; |
79290822 IM |
535 | } |
536 | ||
c4772d99 | 537 | early_param("ignore_loglevel", ignore_loglevel_setup); |
29d4d6df | 538 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); |
0eca6b7c YZ |
539 | MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to" |
540 | "print all kernel messages to the console."); | |
79290822 | 541 | |
1da177e4 LT |
542 | /* |
543 | * Write out chars from start to end - 1 inclusive | |
544 | */ | |
eed4a2ab DV |
545 | static void _call_console_drivers(unsigned start, |
546 | unsigned end, int msg_log_level) | |
1da177e4 | 547 | { |
95100358 JB |
548 | trace_console(&LOG_BUF(0), start, end, log_buf_len); |
549 | ||
79290822 | 550 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
551 | console_drivers && start != end) { |
552 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
553 | /* wrapped write */ | |
554 | __call_console_drivers(start & LOG_BUF_MASK, | |
555 | log_buf_len); | |
556 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
557 | } else { | |
558 | __call_console_drivers(start, end); | |
559 | } | |
560 | } | |
561 | } | |
562 | ||
9d90c8d9 KS |
563 | /* |
564 | * Parse the syslog header <[0-9]*>. The decimal value represents 32bit, the | |
565 | * lower 3 bit are the log level, the rest are the log facility. In case | |
566 | * userspace passes usual userspace syslog messages to /dev/kmsg or | |
567 | * /dev/ttyprintk, the log prefix might contain the facility. Printk needs | |
568 | * to extract the correct log level for in-kernel processing, and not mangle | |
569 | * the original value. | |
570 | * | |
571 | * If a prefix is found, the length of the prefix is returned. If 'level' is | |
572 | * passed, it will be filled in with the log level without a possible facility | |
573 | * value. If 'special' is passed, the special printk prefix chars are accepted | |
574 | * and returned. If no valid header is found, 0 is returned and the passed | |
575 | * variables are not touched. | |
576 | */ | |
577 | static size_t log_prefix(const char *p, unsigned int *level, char *special) | |
578 | { | |
579 | unsigned int lev = 0; | |
580 | char sp = '\0'; | |
581 | size_t len; | |
582 | ||
583 | if (p[0] != '<' || !p[1]) | |
584 | return 0; | |
585 | if (p[2] == '>') { | |
586 | /* usual single digit level number or special char */ | |
587 | switch (p[1]) { | |
588 | case '0' ... '7': | |
589 | lev = p[1] - '0'; | |
590 | break; | |
591 | case 'c': /* KERN_CONT */ | |
592 | case 'd': /* KERN_DEFAULT */ | |
593 | sp = p[1]; | |
594 | break; | |
595 | default: | |
596 | return 0; | |
597 | } | |
598 | len = 3; | |
599 | } else { | |
600 | /* multi digit including the level and facility number */ | |
601 | char *endp = NULL; | |
602 | ||
9d90c8d9 KS |
603 | lev = (simple_strtoul(&p[1], &endp, 10) & 7); |
604 | if (endp == NULL || endp[0] != '>') | |
605 | return 0; | |
606 | len = (endp + 1) - p; | |
607 | } | |
608 | ||
609 | /* do not accept special char if not asked for */ | |
610 | if (sp && !special) | |
611 | return 0; | |
612 | ||
613 | if (special) { | |
614 | *special = sp; | |
615 | /* return special char, do not touch level */ | |
616 | if (sp) | |
617 | return len; | |
618 | } | |
619 | ||
620 | if (level) | |
621 | *level = lev; | |
622 | return len; | |
623 | } | |
624 | ||
1da177e4 LT |
625 | /* |
626 | * Call the console drivers, asking them to write out | |
627 | * log_buf[start] to log_buf[end - 1]. | |
ac751efa | 628 | * The console_lock must be held. |
1da177e4 | 629 | */ |
eed4a2ab | 630 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 631 | { |
eed4a2ab | 632 | unsigned cur_index, start_print; |
1da177e4 LT |
633 | static int msg_level = -1; |
634 | ||
eed4a2ab | 635 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
636 | |
637 | cur_index = start; | |
638 | start_print = start; | |
639 | while (cur_index != end) { | |
9d90c8d9 KS |
640 | if (msg_level < 0 && ((end - cur_index) > 2)) { |
641 | /* strip log prefix */ | |
642 | cur_index += log_prefix(&LOG_BUF(cur_index), &msg_level, NULL); | |
1da177e4 LT |
643 | start_print = cur_index; |
644 | } | |
645 | while (cur_index != end) { | |
646 | char c = LOG_BUF(cur_index); | |
1da177e4 | 647 | |
40dc5651 | 648 | cur_index++; |
1da177e4 LT |
649 | if (c == '\n') { |
650 | if (msg_level < 0) { | |
651 | /* | |
652 | * printk() has already given us loglevel tags in | |
653 | * the buffer. This code is here in case the | |
654 | * log buffer has wrapped right round and scribbled | |
655 | * on those tags | |
656 | */ | |
657 | msg_level = default_message_loglevel; | |
658 | } | |
659 | _call_console_drivers(start_print, cur_index, msg_level); | |
660 | msg_level = -1; | |
661 | start_print = cur_index; | |
662 | break; | |
663 | } | |
664 | } | |
665 | } | |
666 | _call_console_drivers(start_print, end, msg_level); | |
667 | } | |
668 | ||
669 | static void emit_log_char(char c) | |
670 | { | |
671 | LOG_BUF(log_end) = c; | |
672 | log_end++; | |
673 | if (log_end - log_start > log_buf_len) | |
674 | log_start = log_end - log_buf_len; | |
675 | if (log_end - con_start > log_buf_len) | |
676 | con_start = log_end - log_buf_len; | |
677 | if (logged_chars < log_buf_len) | |
678 | logged_chars++; | |
679 | } | |
680 | ||
681 | /* | |
682 | * Zap console related locks when oopsing. Only zap at most once | |
683 | * every 10 seconds, to leave time for slow consoles to print a | |
684 | * full oops. | |
685 | */ | |
686 | static void zap_locks(void) | |
687 | { | |
688 | static unsigned long oops_timestamp; | |
689 | ||
690 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 691 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
692 | return; |
693 | ||
694 | oops_timestamp = jiffies; | |
695 | ||
94d24fc4 | 696 | debug_locks_off(); |
1da177e4 | 697 | /* If a crash is occurring, make sure we can't deadlock */ |
07354eb1 | 698 | raw_spin_lock_init(&logbuf_lock); |
1da177e4 | 699 | /* And make sure that we print immediately */ |
5b8c4f23 | 700 | sema_init(&console_sem, 1); |
1da177e4 LT |
701 | } |
702 | ||
703 | #if defined(CONFIG_PRINTK_TIME) | |
2329abfa | 704 | static bool printk_time = 1; |
1da177e4 | 705 | #else |
2329abfa | 706 | static bool printk_time = 0; |
1da177e4 | 707 | #endif |
e84845c4 | 708 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 709 | |
76a8ad29 ME |
710 | /* Check if we have any console registered that can be called early in boot. */ |
711 | static int have_callable_console(void) | |
712 | { | |
713 | struct console *con; | |
714 | ||
4d091611 | 715 | for_each_console(con) |
76a8ad29 ME |
716 | if (con->flags & CON_ANYTIME) |
717 | return 1; | |
718 | ||
719 | return 0; | |
720 | } | |
721 | ||
ddad86c2 MW |
722 | /** |
723 | * printk - print a kernel message | |
724 | * @fmt: format string | |
725 | * | |
72fd4a35 | 726 | * This is printk(). It can be called from any context. We want it to work. |
40dc5651 | 727 | * |
ac751efa | 728 | * We try to grab the console_lock. If we succeed, it's easy - we log the output and |
1da177e4 LT |
729 | * call the console drivers. If we fail to get the semaphore we place the output |
730 | * into the log buffer and return. The current holder of the console_sem will | |
ac751efa TH |
731 | * notice the new output in console_unlock(); and will send it to the |
732 | * consoles before releasing the lock. | |
1da177e4 LT |
733 | * |
734 | * One effect of this deferred printing is that code which calls printk() and | |
735 | * then changes console_loglevel may break. This is because console_loglevel | |
736 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
737 | * |
738 | * See also: | |
739 | * printf(3) | |
20036fdc AK |
740 | * |
741 | * See the vsnprintf() documentation for format string extensions over C99. | |
1da177e4 | 742 | */ |
d59745ce | 743 | |
1da177e4 LT |
744 | asmlinkage int printk(const char *fmt, ...) |
745 | { | |
746 | va_list args; | |
747 | int r; | |
748 | ||
d37d39ae JW |
749 | #ifdef CONFIG_KGDB_KDB |
750 | if (unlikely(kdb_trap_printk)) { | |
751 | va_start(args, fmt); | |
752 | r = vkdb_printf(fmt, args); | |
753 | va_end(args); | |
754 | return r; | |
755 | } | |
756 | #endif | |
1da177e4 LT |
757 | va_start(args, fmt); |
758 | r = vprintk(fmt, args); | |
759 | va_end(args); | |
760 | ||
761 | return r; | |
762 | } | |
763 | ||
fe21773d DH |
764 | /* cpu currently holding logbuf_lock */ |
765 | static volatile unsigned int printk_cpu = UINT_MAX; | |
766 | ||
266c2e0a LT |
767 | /* |
768 | * Can we actually use the console at this time on this cpu? | |
769 | * | |
770 | * Console drivers may assume that per-cpu resources have | |
771 | * been allocated. So unless they're explicitly marked as | |
772 | * being able to cope (CON_ANYTIME) don't call them until | |
773 | * this CPU is officially up. | |
774 | */ | |
775 | static inline int can_use_console(unsigned int cpu) | |
776 | { | |
777 | return cpu_online(cpu) || have_callable_console(); | |
778 | } | |
779 | ||
780 | /* | |
781 | * Try to get console ownership to actually show the kernel | |
782 | * messages from a 'printk'. Return true (and with the | |
ac751efa | 783 | * console_lock held, and 'console_locked' set) if it |
266c2e0a LT |
784 | * is successful, false otherwise. |
785 | * | |
786 | * This gets called with the 'logbuf_lock' spinlock held and | |
787 | * interrupts disabled. It should return with 'lockbuf_lock' | |
788 | * released but interrupts still disabled. | |
789 | */ | |
ac751efa | 790 | static int console_trylock_for_printk(unsigned int cpu) |
8155c02a | 791 | __releases(&logbuf_lock) |
266c2e0a | 792 | { |
0b5e1c52 | 793 | int retval = 0, wake = 0; |
266c2e0a | 794 | |
ac751efa | 795 | if (console_trylock()) { |
093a07e2 LT |
796 | retval = 1; |
797 | ||
798 | /* | |
799 | * If we can't use the console, we need to release | |
800 | * the console semaphore by hand to avoid flushing | |
801 | * the buffer. We need to hold the console semaphore | |
802 | * in order to do this test safely. | |
803 | */ | |
804 | if (!can_use_console(cpu)) { | |
805 | console_locked = 0; | |
0b5e1c52 | 806 | wake = 1; |
093a07e2 LT |
807 | retval = 0; |
808 | } | |
809 | } | |
266c2e0a | 810 | printk_cpu = UINT_MAX; |
0b5e1c52 PZ |
811 | if (wake) |
812 | up(&console_sem); | |
07354eb1 | 813 | raw_spin_unlock(&logbuf_lock); |
266c2e0a LT |
814 | return retval; |
815 | } | |
3b8945e8 TH |
816 | static const char recursion_bug_msg [] = |
817 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
818 | static int recursion_bug; | |
edb123e1 | 819 | static int new_text_line = 1; |
3b8945e8 | 820 | static char printk_buf[1024]; |
32a76006 | 821 | |
af91322e DY |
822 | int printk_delay_msec __read_mostly; |
823 | ||
824 | static inline void printk_delay(void) | |
825 | { | |
826 | if (unlikely(printk_delay_msec)) { | |
827 | int m = printk_delay_msec; | |
828 | ||
829 | while (m--) { | |
830 | mdelay(1); | |
831 | touch_nmi_watchdog(); | |
832 | } | |
833 | } | |
834 | } | |
835 | ||
1da177e4 LT |
836 | asmlinkage int vprintk(const char *fmt, va_list args) |
837 | { | |
32a76006 | 838 | int printed_len = 0; |
09159308 | 839 | int current_log_level = default_message_loglevel; |
ac60ad74 | 840 | unsigned long flags; |
32a76006 | 841 | int this_cpu; |
1da177e4 | 842 | char *p; |
9d90c8d9 KS |
843 | size_t plen; |
844 | char special; | |
1da177e4 | 845 | |
bfe8df3d | 846 | boot_delay_msec(); |
af91322e | 847 | printk_delay(); |
bfe8df3d | 848 | |
1da177e4 | 849 | /* This stops the holder of console_sem just where we want him */ |
1a9a8aef | 850 | local_irq_save(flags); |
32a76006 IM |
851 | this_cpu = smp_processor_id(); |
852 | ||
853 | /* | |
854 | * Ouch, printk recursed into itself! | |
855 | */ | |
856 | if (unlikely(printk_cpu == this_cpu)) { | |
857 | /* | |
858 | * If a crash is occurring during printk() on this CPU, | |
859 | * then try to get the crash message out but make sure | |
860 | * we can't deadlock. Otherwise just return to avoid the | |
861 | * recursion and return - but flag the recursion so that | |
862 | * it can be printed at the next appropriate moment: | |
863 | */ | |
94d24fc4 | 864 | if (!oops_in_progress && !lockdep_recursing(current)) { |
3b8945e8 | 865 | recursion_bug = 1; |
32a76006 IM |
866 | goto out_restore_irqs; |
867 | } | |
868 | zap_locks(); | |
869 | } | |
870 | ||
a0f1ccfd | 871 | lockdep_off(); |
07354eb1 | 872 | raw_spin_lock(&logbuf_lock); |
32a76006 | 873 | printk_cpu = this_cpu; |
1da177e4 | 874 | |
3b8945e8 TH |
875 | if (recursion_bug) { |
876 | recursion_bug = 0; | |
877 | strcpy(printk_buf, recursion_bug_msg); | |
26cc271d | 878 | printed_len = strlen(recursion_bug_msg); |
32a76006 | 879 | } |
1da177e4 | 880 | /* Emit the output into the temporary buffer */ |
32a76006 | 881 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 882 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 883 | |
5fd29d6c LT |
884 | p = printk_buf; |
885 | ||
9d90c8d9 KS |
886 | /* Read log level and handle special printk prefix */ |
887 | plen = log_prefix(p, ¤t_log_level, &special); | |
888 | if (plen) { | |
889 | p += plen; | |
890 | ||
891 | switch (special) { | |
892 | case 'c': /* Strip <c> KERN_CONT, continue line */ | |
893 | plen = 0; | |
894 | break; | |
895 | case 'd': /* Strip <d> KERN_DEFAULT, start new line */ | |
896 | plen = 0; | |
897 | default: | |
898 | if (!new_text_line) { | |
899 | emit_log_char('\n'); | |
900 | new_text_line = 1; | |
5fd29d6c LT |
901 | } |
902 | } | |
903 | } | |
904 | ||
1da177e4 | 905 | /* |
9d90c8d9 KS |
906 | * Copy the output into log_buf. If the caller didn't provide |
907 | * the appropriate log prefix, we insert them here | |
1da177e4 | 908 | */ |
9d90c8d9 | 909 | for (; *p; p++) { |
ac60ad74 | 910 | if (new_text_line) { |
ac60ad74 NA |
911 | new_text_line = 0; |
912 | ||
9d90c8d9 KS |
913 | if (plen) { |
914 | /* Copy original log prefix */ | |
915 | int i; | |
916 | ||
917 | for (i = 0; i < plen; i++) | |
918 | emit_log_char(printk_buf[i]); | |
919 | printed_len += plen; | |
920 | } else { | |
921 | /* Add log prefix */ | |
922 | emit_log_char('<'); | |
923 | emit_log_char(current_log_level + '0'); | |
924 | emit_log_char('>'); | |
925 | printed_len += 3; | |
926 | } | |
927 | ||
1da177e4 | 928 | if (printk_time) { |
9d90c8d9 | 929 | /* Add the current time stamp */ |
1da177e4 LT |
930 | char tbuf[50], *tp; |
931 | unsigned tlen; | |
932 | unsigned long long t; | |
933 | unsigned long nanosec_rem; | |
934 | ||
326e96b9 | 935 | t = cpu_clock(printk_cpu); |
1da177e4 | 936 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
937 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
938 | (unsigned long) t, | |
939 | nanosec_rem / 1000); | |
1da177e4 LT |
940 | |
941 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
942 | emit_log_char(*tp); | |
025510cd | 943 | printed_len += tlen; |
1da177e4 | 944 | } |
ac60ad74 | 945 | |
1da177e4 LT |
946 | if (!*p) |
947 | break; | |
948 | } | |
ac60ad74 | 949 | |
1da177e4 LT |
950 | emit_log_char(*p); |
951 | if (*p == '\n') | |
ac60ad74 | 952 | new_text_line = 1; |
1da177e4 LT |
953 | } |
954 | ||
266c2e0a LT |
955 | /* |
956 | * Try to acquire and then immediately release the | |
957 | * console semaphore. The release will do all the | |
958 | * actual magic (print out buffers, wake up klogd, | |
959 | * etc). | |
960 | * | |
ac751efa | 961 | * The console_trylock_for_printk() function |
266c2e0a LT |
962 | * will release 'logbuf_lock' regardless of whether it |
963 | * actually gets the semaphore or not. | |
964 | */ | |
ac751efa TH |
965 | if (console_trylock_for_printk(this_cpu)) |
966 | console_unlock(); | |
76a8ad29 | 967 | |
266c2e0a | 968 | lockdep_on(); |
32a76006 | 969 | out_restore_irqs: |
1a9a8aef | 970 | local_irq_restore(flags); |
76a8ad29 | 971 | |
1da177e4 LT |
972 | return printed_len; |
973 | } | |
974 | EXPORT_SYMBOL(printk); | |
975 | EXPORT_SYMBOL(vprintk); | |
976 | ||
d59745ce MM |
977 | #else |
978 | ||
eed4a2ab | 979 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
980 | { |
981 | } | |
d59745ce MM |
982 | |
983 | #endif | |
984 | ||
f7511d5f ST |
985 | static int __add_preferred_console(char *name, int idx, char *options, |
986 | char *brl_options) | |
987 | { | |
988 | struct console_cmdline *c; | |
989 | int i; | |
990 | ||
991 | /* | |
992 | * See if this tty is not yet registered, and | |
993 | * if we have a slot free. | |
994 | */ | |
995 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
996 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
997 | console_cmdline[i].index == idx) { | |
998 | if (!brl_options) | |
999 | selected_console = i; | |
1000 | return 0; | |
1001 | } | |
1002 | if (i == MAX_CMDLINECONSOLES) | |
1003 | return -E2BIG; | |
1004 | if (!brl_options) | |
1005 | selected_console = i; | |
1006 | c = &console_cmdline[i]; | |
1007 | strlcpy(c->name, name, sizeof(c->name)); | |
1008 | c->options = options; | |
1009 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
1010 | c->brl_options = brl_options; | |
1011 | #endif | |
1012 | c->index = idx; | |
1013 | return 0; | |
1014 | } | |
2ea1c539 JB |
1015 | /* |
1016 | * Set up a list of consoles. Called from init/main.c | |
1017 | */ | |
1018 | static int __init console_setup(char *str) | |
1019 | { | |
eaa944af | 1020 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 1021 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
1022 | int idx; |
1023 | ||
f7511d5f ST |
1024 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1025 | if (!memcmp(str, "brl,", 4)) { | |
1026 | brl_options = ""; | |
1027 | str += 4; | |
1028 | } else if (!memcmp(str, "brl=", 4)) { | |
1029 | brl_options = str + 4; | |
1030 | str = strchr(brl_options, ','); | |
1031 | if (!str) { | |
1032 | printk(KERN_ERR "need port name after brl=\n"); | |
1033 | return 1; | |
1034 | } | |
1035 | *(str++) = 0; | |
1036 | } | |
1037 | #endif | |
1038 | ||
2ea1c539 JB |
1039 | /* |
1040 | * Decode str into name, index, options. | |
1041 | */ | |
1042 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
1043 | strcpy(buf, "ttyS"); |
1044 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 1045 | } else { |
eaa944af | 1046 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 1047 | } |
eaa944af | 1048 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
1049 | if ((options = strchr(str, ',')) != NULL) |
1050 | *(options++) = 0; | |
1051 | #ifdef __sparc__ | |
1052 | if (!strcmp(str, "ttya")) | |
eaa944af | 1053 | strcpy(buf, "ttyS0"); |
2ea1c539 | 1054 | if (!strcmp(str, "ttyb")) |
eaa944af | 1055 | strcpy(buf, "ttyS1"); |
2ea1c539 | 1056 | #endif |
eaa944af | 1057 | for (s = buf; *s; s++) |
2ea1c539 JB |
1058 | if ((*s >= '0' && *s <= '9') || *s == ',') |
1059 | break; | |
1060 | idx = simple_strtoul(s, NULL, 10); | |
1061 | *s = 0; | |
1062 | ||
f7511d5f | 1063 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 1064 | console_set_on_cmdline = 1; |
2ea1c539 JB |
1065 | return 1; |
1066 | } | |
1067 | __setup("console=", console_setup); | |
1068 | ||
3c0547ba MM |
1069 | /** |
1070 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
1071 | * @name: device name |
1072 | * @idx: device index | |
1073 | * @options: options for this console | |
3c0547ba MM |
1074 | * |
1075 | * The last preferred console added will be used for kernel messages | |
1076 | * and stdin/out/err for init. Normally this is used by console_setup | |
1077 | * above to handle user-supplied console arguments; however it can also | |
1078 | * be used by arch-specific code either to override the user or more | |
1079 | * commonly to provide a default console (ie from PROM variables) when | |
1080 | * the user has not supplied one. | |
1081 | */ | |
fb445ee5 | 1082 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 1083 | { |
f7511d5f | 1084 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
1085 | } |
1086 | ||
b6b1d877 | 1087 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
1088 | { |
1089 | struct console_cmdline *c; | |
1090 | int i; | |
1091 | ||
1092 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
1093 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
1094 | console_cmdline[i].index == idx) { | |
1095 | c = &console_cmdline[i]; | |
f735295b | 1096 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
1097 | c->name[sizeof(c->name) - 1] = 0; |
1098 | c->options = options; | |
1099 | c->index = idx_new; | |
1100 | return i; | |
1101 | } | |
1102 | /* not found */ | |
1103 | return -1; | |
1104 | } | |
1105 | ||
2329abfa | 1106 | bool console_suspend_enabled = 1; |
8f4ce8c3 AS |
1107 | EXPORT_SYMBOL(console_suspend_enabled); |
1108 | ||
1109 | static int __init console_suspend_disable(char *str) | |
1110 | { | |
1111 | console_suspend_enabled = 0; | |
1112 | return 1; | |
1113 | } | |
1114 | __setup("no_console_suspend", console_suspend_disable); | |
134620f7 YZ |
1115 | module_param_named(console_suspend, console_suspend_enabled, |
1116 | bool, S_IRUGO | S_IWUSR); | |
1117 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" | |
1118 | " and hibernate operations"); | |
8f4ce8c3 | 1119 | |
557240b4 LT |
1120 | /** |
1121 | * suspend_console - suspend the console subsystem | |
1122 | * | |
1123 | * This disables printk() while we go into suspend states | |
1124 | */ | |
1125 | void suspend_console(void) | |
1126 | { | |
8f4ce8c3 AS |
1127 | if (!console_suspend_enabled) |
1128 | return; | |
0d63081d | 1129 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
ac751efa | 1130 | console_lock(); |
557240b4 | 1131 | console_suspended = 1; |
403f3075 | 1132 | up(&console_sem); |
557240b4 LT |
1133 | } |
1134 | ||
1135 | void resume_console(void) | |
1136 | { | |
8f4ce8c3 AS |
1137 | if (!console_suspend_enabled) |
1138 | return; | |
403f3075 | 1139 | down(&console_sem); |
557240b4 | 1140 | console_suspended = 0; |
ac751efa | 1141 | console_unlock(); |
557240b4 LT |
1142 | } |
1143 | ||
034260d6 KC |
1144 | /** |
1145 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
1146 | * @self: notifier struct | |
1147 | * @action: CPU hotplug event | |
1148 | * @hcpu: unused | |
1149 | * | |
1150 | * If printk() is called from a CPU that is not online yet, the messages | |
1151 | * will be spooled but will not show up on the console. This function is | |
1152 | * called when a new CPU comes online (or fails to come up), and ensures | |
1153 | * that any such output gets printed. | |
1154 | */ | |
1155 | static int __cpuinit console_cpu_notify(struct notifier_block *self, | |
1156 | unsigned long action, void *hcpu) | |
1157 | { | |
1158 | switch (action) { | |
1159 | case CPU_ONLINE: | |
1160 | case CPU_DEAD: | |
1161 | case CPU_DYING: | |
1162 | case CPU_DOWN_FAILED: | |
1163 | case CPU_UP_CANCELED: | |
ac751efa TH |
1164 | console_lock(); |
1165 | console_unlock(); | |
034260d6 KC |
1166 | } |
1167 | return NOTIFY_OK; | |
1168 | } | |
1169 | ||
1da177e4 | 1170 | /** |
ac751efa | 1171 | * console_lock - lock the console system for exclusive use. |
1da177e4 | 1172 | * |
ac751efa | 1173 | * Acquires a lock which guarantees that the caller has |
1da177e4 LT |
1174 | * exclusive access to the console system and the console_drivers list. |
1175 | * | |
1176 | * Can sleep, returns nothing. | |
1177 | */ | |
ac751efa | 1178 | void console_lock(void) |
1da177e4 | 1179 | { |
8abd8e29 | 1180 | BUG_ON(in_interrupt()); |
1da177e4 | 1181 | down(&console_sem); |
403f3075 AH |
1182 | if (console_suspended) |
1183 | return; | |
1da177e4 LT |
1184 | console_locked = 1; |
1185 | console_may_schedule = 1; | |
1186 | } | |
ac751efa | 1187 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 1188 | |
ac751efa TH |
1189 | /** |
1190 | * console_trylock - try to lock the console system for exclusive use. | |
1191 | * | |
1192 | * Tried to acquire a lock which guarantees that the caller has | |
1193 | * exclusive access to the console system and the console_drivers list. | |
1194 | * | |
1195 | * returns 1 on success, and 0 on failure to acquire the lock. | |
1196 | */ | |
1197 | int console_trylock(void) | |
1da177e4 LT |
1198 | { |
1199 | if (down_trylock(&console_sem)) | |
ac751efa | 1200 | return 0; |
403f3075 AH |
1201 | if (console_suspended) { |
1202 | up(&console_sem); | |
ac751efa | 1203 | return 0; |
403f3075 | 1204 | } |
1da177e4 LT |
1205 | console_locked = 1; |
1206 | console_may_schedule = 0; | |
ac751efa | 1207 | return 1; |
1da177e4 | 1208 | } |
ac751efa | 1209 | EXPORT_SYMBOL(console_trylock); |
1da177e4 LT |
1210 | |
1211 | int is_console_locked(void) | |
1212 | { | |
1213 | return console_locked; | |
1214 | } | |
1da177e4 | 1215 | |
b845b517 PZ |
1216 | static DEFINE_PER_CPU(int, printk_pending); |
1217 | ||
1218 | void printk_tick(void) | |
e3e8a75d | 1219 | { |
40dc11ff ED |
1220 | if (__this_cpu_read(printk_pending)) { |
1221 | __this_cpu_write(printk_pending, 0); | |
e3e8a75d | 1222 | wake_up_interruptible(&log_wait); |
b845b517 PZ |
1223 | } |
1224 | } | |
1225 | ||
1226 | int printk_needs_cpu(int cpu) | |
1227 | { | |
40dc11ff | 1228 | if (cpu_is_offline(cpu)) |
61ab2544 | 1229 | printk_tick(); |
40dc11ff | 1230 | return __this_cpu_read(printk_pending); |
b845b517 PZ |
1231 | } |
1232 | ||
1233 | void wake_up_klogd(void) | |
1234 | { | |
1235 | if (waitqueue_active(&log_wait)) | |
49f41383 | 1236 | this_cpu_write(printk_pending, 1); |
e3e8a75d KK |
1237 | } |
1238 | ||
1da177e4 | 1239 | /** |
ac751efa | 1240 | * console_unlock - unlock the console system |
1da177e4 | 1241 | * |
ac751efa | 1242 | * Releases the console_lock which the caller holds on the console system |
1da177e4 LT |
1243 | * and the console driver list. |
1244 | * | |
ac751efa TH |
1245 | * While the console_lock was held, console output may have been buffered |
1246 | * by printk(). If this is the case, console_unlock(); emits | |
1247 | * the output prior to releasing the lock. | |
1da177e4 LT |
1248 | * |
1249 | * If there is output waiting for klogd, we wake it up. | |
1250 | * | |
ac751efa | 1251 | * console_unlock(); may be called from any context. |
1da177e4 | 1252 | */ |
ac751efa | 1253 | void console_unlock(void) |
1da177e4 LT |
1254 | { |
1255 | unsigned long flags; | |
eed4a2ab | 1256 | unsigned _con_start, _log_end; |
4f2a8d3c | 1257 | unsigned wake_klogd = 0, retry = 0; |
1da177e4 | 1258 | |
557240b4 | 1259 | if (console_suspended) { |
403f3075 | 1260 | up(&console_sem); |
557240b4 LT |
1261 | return; |
1262 | } | |
78944e54 AD |
1263 | |
1264 | console_may_schedule = 0; | |
1265 | ||
4f2a8d3c | 1266 | again: |
1da177e4 | 1267 | for ( ; ; ) { |
07354eb1 | 1268 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
1da177e4 LT |
1269 | wake_klogd |= log_start - log_end; |
1270 | if (con_start == log_end) | |
1271 | break; /* Nothing to print */ | |
1272 | _con_start = con_start; | |
1273 | _log_end = log_end; | |
1274 | con_start = log_end; /* Flush */ | |
07354eb1 | 1275 | raw_spin_unlock(&logbuf_lock); |
81d68a96 | 1276 | stop_critical_timings(); /* don't trace print latency */ |
1da177e4 | 1277 | call_console_drivers(_con_start, _log_end); |
81d68a96 | 1278 | start_critical_timings(); |
1da177e4 LT |
1279 | local_irq_restore(flags); |
1280 | } | |
1281 | console_locked = 0; | |
fe3d8ad3 FT |
1282 | |
1283 | /* Release the exclusive_console once it is used */ | |
1284 | if (unlikely(exclusive_console)) | |
1285 | exclusive_console = NULL; | |
1286 | ||
07354eb1 | 1287 | raw_spin_unlock(&logbuf_lock); |
4f2a8d3c | 1288 | |
0b5e1c52 | 1289 | up(&console_sem); |
4f2a8d3c PZ |
1290 | |
1291 | /* | |
1292 | * Someone could have filled up the buffer again, so re-check if there's | |
1293 | * something to flush. In case we cannot trylock the console_sem again, | |
1294 | * there's a new owner and the console_unlock() from them will do the | |
1295 | * flush, no worries. | |
1296 | */ | |
07354eb1 | 1297 | raw_spin_lock(&logbuf_lock); |
4f2a8d3c PZ |
1298 | if (con_start != log_end) |
1299 | retry = 1; | |
09dc3cf9 PZ |
1300 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
1301 | ||
4f2a8d3c PZ |
1302 | if (retry && console_trylock()) |
1303 | goto again; | |
1304 | ||
e3e8a75d KK |
1305 | if (wake_klogd) |
1306 | wake_up_klogd(); | |
1da177e4 | 1307 | } |
ac751efa | 1308 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 1309 | |
ddad86c2 MW |
1310 | /** |
1311 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1312 | * |
1313 | * If the console code is currently allowed to sleep, and | |
1314 | * if this CPU should yield the CPU to another task, do | |
1315 | * so here. | |
1316 | * | |
ac751efa | 1317 | * Must be called within console_lock();. |
1da177e4 LT |
1318 | */ |
1319 | void __sched console_conditional_schedule(void) | |
1320 | { | |
1321 | if (console_may_schedule) | |
1322 | cond_resched(); | |
1323 | } | |
1324 | EXPORT_SYMBOL(console_conditional_schedule); | |
1325 | ||
1da177e4 LT |
1326 | void console_unblank(void) |
1327 | { | |
1328 | struct console *c; | |
1329 | ||
1330 | /* | |
1331 | * console_unblank can no longer be called in interrupt context unless | |
1332 | * oops_in_progress is set to 1.. | |
1333 | */ | |
1334 | if (oops_in_progress) { | |
1335 | if (down_trylock(&console_sem) != 0) | |
1336 | return; | |
1337 | } else | |
ac751efa | 1338 | console_lock(); |
1da177e4 LT |
1339 | |
1340 | console_locked = 1; | |
1341 | console_may_schedule = 0; | |
4d091611 | 1342 | for_each_console(c) |
1da177e4 LT |
1343 | if ((c->flags & CON_ENABLED) && c->unblank) |
1344 | c->unblank(); | |
ac751efa | 1345 | console_unlock(); |
1da177e4 | 1346 | } |
1da177e4 LT |
1347 | |
1348 | /* | |
1349 | * Return the console tty driver structure and its associated index | |
1350 | */ | |
1351 | struct tty_driver *console_device(int *index) | |
1352 | { | |
1353 | struct console *c; | |
1354 | struct tty_driver *driver = NULL; | |
1355 | ||
ac751efa | 1356 | console_lock(); |
4d091611 | 1357 | for_each_console(c) { |
1da177e4 LT |
1358 | if (!c->device) |
1359 | continue; | |
1360 | driver = c->device(c, index); | |
1361 | if (driver) | |
1362 | break; | |
1363 | } | |
ac751efa | 1364 | console_unlock(); |
1da177e4 LT |
1365 | return driver; |
1366 | } | |
1367 | ||
1368 | /* | |
1369 | * Prevent further output on the passed console device so that (for example) | |
1370 | * serial drivers can disable console output before suspending a port, and can | |
1371 | * re-enable output afterwards. | |
1372 | */ | |
1373 | void console_stop(struct console *console) | |
1374 | { | |
ac751efa | 1375 | console_lock(); |
1da177e4 | 1376 | console->flags &= ~CON_ENABLED; |
ac751efa | 1377 | console_unlock(); |
1da177e4 LT |
1378 | } |
1379 | EXPORT_SYMBOL(console_stop); | |
1380 | ||
1381 | void console_start(struct console *console) | |
1382 | { | |
ac751efa | 1383 | console_lock(); |
1da177e4 | 1384 | console->flags |= CON_ENABLED; |
ac751efa | 1385 | console_unlock(); |
1da177e4 LT |
1386 | } |
1387 | EXPORT_SYMBOL(console_start); | |
1388 | ||
7bf69395 FDN |
1389 | static int __read_mostly keep_bootcon; |
1390 | ||
1391 | static int __init keep_bootcon_setup(char *str) | |
1392 | { | |
1393 | keep_bootcon = 1; | |
1394 | printk(KERN_INFO "debug: skip boot console de-registration.\n"); | |
1395 | ||
1396 | return 0; | |
1397 | } | |
1398 | ||
1399 | early_param("keep_bootcon", keep_bootcon_setup); | |
1400 | ||
1da177e4 LT |
1401 | /* |
1402 | * The console driver calls this routine during kernel initialization | |
1403 | * to register the console printing procedure with printk() and to | |
1404 | * print any messages that were printed by the kernel before the | |
1405 | * console driver was initialized. | |
4d091611 RG |
1406 | * |
1407 | * This can happen pretty early during the boot process (because of | |
1408 | * early_printk) - sometimes before setup_arch() completes - be careful | |
1409 | * of what kernel features are used - they may not be initialised yet. | |
1410 | * | |
1411 | * There are two types of consoles - bootconsoles (early_printk) and | |
1412 | * "real" consoles (everything which is not a bootconsole) which are | |
1413 | * handled differently. | |
1414 | * - Any number of bootconsoles can be registered at any time. | |
1415 | * - As soon as a "real" console is registered, all bootconsoles | |
1416 | * will be unregistered automatically. | |
1417 | * - Once a "real" console is registered, any attempt to register a | |
1418 | * bootconsoles will be rejected | |
1da177e4 | 1419 | */ |
4d091611 | 1420 | void register_console(struct console *newcon) |
1da177e4 | 1421 | { |
40dc5651 | 1422 | int i; |
1da177e4 | 1423 | unsigned long flags; |
4d091611 | 1424 | struct console *bcon = NULL; |
1da177e4 | 1425 | |
4d091611 RG |
1426 | /* |
1427 | * before we register a new CON_BOOT console, make sure we don't | |
1428 | * already have a valid console | |
1429 | */ | |
1430 | if (console_drivers && newcon->flags & CON_BOOT) { | |
1431 | /* find the last or real console */ | |
1432 | for_each_console(bcon) { | |
1433 | if (!(bcon->flags & CON_BOOT)) { | |
1434 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", | |
1435 | newcon->name, newcon->index); | |
1436 | return; | |
1437 | } | |
1438 | } | |
69331af7 GH |
1439 | } |
1440 | ||
4d091611 RG |
1441 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1442 | bcon = console_drivers; | |
1443 | ||
1444 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
1445 | preferred_console = selected_console; |
1446 | ||
4d091611 RG |
1447 | if (newcon->early_setup) |
1448 | newcon->early_setup(); | |
18a8bd94 | 1449 | |
1da177e4 LT |
1450 | /* |
1451 | * See if we want to use this console driver. If we | |
1452 | * didn't select a console we take the first one | |
1453 | * that registers here. | |
1454 | */ | |
1455 | if (preferred_console < 0) { | |
4d091611 RG |
1456 | if (newcon->index < 0) |
1457 | newcon->index = 0; | |
1458 | if (newcon->setup == NULL || | |
1459 | newcon->setup(newcon, NULL) == 0) { | |
1460 | newcon->flags |= CON_ENABLED; | |
1461 | if (newcon->device) { | |
1462 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
1463 | preferred_console = 0; |
1464 | } | |
1da177e4 LT |
1465 | } |
1466 | } | |
1467 | ||
1468 | /* | |
1469 | * See if this console matches one we selected on | |
1470 | * the command line. | |
1471 | */ | |
40dc5651 JJ |
1472 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1473 | i++) { | |
4d091611 | 1474 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1da177e4 | 1475 | continue; |
4d091611 RG |
1476 | if (newcon->index >= 0 && |
1477 | newcon->index != console_cmdline[i].index) | |
1da177e4 | 1478 | continue; |
4d091611 RG |
1479 | if (newcon->index < 0) |
1480 | newcon->index = console_cmdline[i].index; | |
f7511d5f ST |
1481 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1482 | if (console_cmdline[i].brl_options) { | |
4d091611 RG |
1483 | newcon->flags |= CON_BRL; |
1484 | braille_register_console(newcon, | |
f7511d5f ST |
1485 | console_cmdline[i].index, |
1486 | console_cmdline[i].options, | |
1487 | console_cmdline[i].brl_options); | |
1488 | return; | |
1489 | } | |
1490 | #endif | |
4d091611 RG |
1491 | if (newcon->setup && |
1492 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 1493 | break; |
4d091611 RG |
1494 | newcon->flags |= CON_ENABLED; |
1495 | newcon->index = console_cmdline[i].index; | |
ab4af03a | 1496 | if (i == selected_console) { |
4d091611 | 1497 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
1498 | preferred_console = selected_console; |
1499 | } | |
1da177e4 LT |
1500 | break; |
1501 | } | |
1502 | ||
4d091611 | 1503 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
1504 | return; |
1505 | ||
8259cf43 RG |
1506 | /* |
1507 | * If we have a bootconsole, and are switching to a real console, | |
1508 | * don't print everything out again, since when the boot console, and | |
1509 | * the real console are the same physical device, it's annoying to | |
1510 | * see the beginning boot messages twice | |
1511 | */ | |
1512 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 1513 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
1514 | |
1515 | /* | |
1516 | * Put this console in the list - keep the | |
1517 | * preferred driver at the head of the list. | |
1518 | */ | |
ac751efa | 1519 | console_lock(); |
4d091611 RG |
1520 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1521 | newcon->next = console_drivers; | |
1522 | console_drivers = newcon; | |
1523 | if (newcon->next) | |
1524 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 1525 | } else { |
4d091611 RG |
1526 | newcon->next = console_drivers->next; |
1527 | console_drivers->next = newcon; | |
1da177e4 | 1528 | } |
4d091611 | 1529 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 | 1530 | /* |
ac751efa | 1531 | * console_unlock(); will print out the buffered messages |
1da177e4 LT |
1532 | * for us. |
1533 | */ | |
07354eb1 | 1534 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
1da177e4 | 1535 | con_start = log_start; |
07354eb1 | 1536 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
fe3d8ad3 FT |
1537 | /* |
1538 | * We're about to replay the log buffer. Only do this to the | |
1539 | * just-registered console to avoid excessive message spam to | |
1540 | * the already-registered consoles. | |
1541 | */ | |
1542 | exclusive_console = newcon; | |
1da177e4 | 1543 | } |
ac751efa | 1544 | console_unlock(); |
fbc92a34 | 1545 | console_sysfs_notify(); |
8259cf43 RG |
1546 | |
1547 | /* | |
1548 | * By unregistering the bootconsoles after we enable the real console | |
1549 | * we get the "console xxx enabled" message on all the consoles - | |
1550 | * boot consoles, real consoles, etc - this is to ensure that end | |
1551 | * users know there might be something in the kernel's log buffer that | |
1552 | * went to the bootconsole (that they do not see on the real console) | |
1553 | */ | |
7bf69395 FDN |
1554 | if (bcon && |
1555 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && | |
1556 | !keep_bootcon) { | |
8259cf43 RG |
1557 | /* we need to iterate through twice, to make sure we print |
1558 | * everything out, before we unregister the console(s) | |
1559 | */ | |
1560 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", | |
1561 | newcon->name, newcon->index); | |
1562 | for_each_console(bcon) | |
1563 | if (bcon->flags & CON_BOOT) | |
1564 | unregister_console(bcon); | |
1565 | } else { | |
1566 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", | |
1567 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
1568 | newcon->name, newcon->index); | |
1569 | } | |
1da177e4 LT |
1570 | } |
1571 | EXPORT_SYMBOL(register_console); | |
1572 | ||
40dc5651 | 1573 | int unregister_console(struct console *console) |
1da177e4 | 1574 | { |
40dc5651 | 1575 | struct console *a, *b; |
1da177e4 LT |
1576 | int res = 1; |
1577 | ||
f7511d5f ST |
1578 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1579 | if (console->flags & CON_BRL) | |
1580 | return braille_unregister_console(console); | |
1581 | #endif | |
1582 | ||
ac751efa | 1583 | console_lock(); |
1da177e4 LT |
1584 | if (console_drivers == console) { |
1585 | console_drivers=console->next; | |
1586 | res = 0; | |
e9b15b54 | 1587 | } else if (console_drivers) { |
1da177e4 LT |
1588 | for (a=console_drivers->next, b=console_drivers ; |
1589 | a; b=a, a=b->next) { | |
1590 | if (a == console) { | |
1591 | b->next = a->next; | |
1592 | res = 0; | |
1593 | break; | |
40dc5651 | 1594 | } |
1da177e4 LT |
1595 | } |
1596 | } | |
40dc5651 | 1597 | |
69331af7 | 1598 | /* |
ab4af03a GE |
1599 | * If this isn't the last console and it has CON_CONSDEV set, we |
1600 | * need to set it on the next preferred console. | |
1da177e4 | 1601 | */ |
69331af7 | 1602 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1603 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 | 1604 | |
ac751efa | 1605 | console_unlock(); |
fbc92a34 | 1606 | console_sysfs_notify(); |
1da177e4 LT |
1607 | return res; |
1608 | } | |
1609 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1610 | |
034260d6 | 1611 | static int __init printk_late_init(void) |
0c5564bd | 1612 | { |
4d091611 RG |
1613 | struct console *con; |
1614 | ||
1615 | for_each_console(con) { | |
4c30c6f5 | 1616 | if (!keep_bootcon && con->flags & CON_BOOT) { |
cb00e99c | 1617 | printk(KERN_INFO "turn off boot console %s%d\n", |
4d091611 | 1618 | con->name, con->index); |
42c2c8c8 | 1619 | unregister_console(con); |
cb00e99c | 1620 | } |
0c5564bd | 1621 | } |
034260d6 | 1622 | hotcpu_notifier(console_cpu_notify, 0); |
0c5564bd RG |
1623 | return 0; |
1624 | } | |
034260d6 | 1625 | late_initcall(printk_late_init); |
0c5564bd | 1626 | |
7ef3d2fd | 1627 | #if defined CONFIG_PRINTK |
717115e1 | 1628 | |
1da177e4 LT |
1629 | /* |
1630 | * printk rate limiting, lifted from the networking subsystem. | |
1631 | * | |
641de9d8 UKK |
1632 | * This enforces a rate limit: not more than 10 kernel messages |
1633 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 1634 | */ |
641de9d8 UKK |
1635 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1636 | ||
5c828713 | 1637 | int __printk_ratelimit(const char *func) |
1da177e4 | 1638 | { |
5c828713 | 1639 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 1640 | } |
5c828713 | 1641 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
1642 | |
1643 | /** | |
1644 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1645 | * @caller_jiffies: pointer to caller's state | |
1646 | * @interval_msecs: minimum interval between prints | |
1647 | * | |
1648 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1649 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1650 | * returned true. | |
1651 | */ | |
1652 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1653 | unsigned int interval_msecs) | |
1654 | { | |
f2d28a2e GK |
1655 | if (*caller_jiffies == 0 |
1656 | || !time_in_range(jiffies, *caller_jiffies, | |
1657 | *caller_jiffies | |
1658 | + msecs_to_jiffies(interval_msecs))) { | |
1659 | *caller_jiffies = jiffies; | |
f46c4833 AM |
1660 | return true; |
1661 | } | |
1662 | return false; | |
1663 | } | |
1664 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
1665 | |
1666 | static DEFINE_SPINLOCK(dump_list_lock); | |
1667 | static LIST_HEAD(dump_list); | |
1668 | ||
1669 | /** | |
1670 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 1671 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1672 | * |
1673 | * Adds a kernel log dumper to the system. The dump callback in the | |
1674 | * structure will be called when the kernel oopses or panics and must be | |
1675 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
1676 | */ | |
1677 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
1678 | { | |
1679 | unsigned long flags; | |
1680 | int err = -EBUSY; | |
1681 | ||
1682 | /* The dump callback needs to be set */ | |
1683 | if (!dumper->dump) | |
1684 | return -EINVAL; | |
1685 | ||
1686 | spin_lock_irqsave(&dump_list_lock, flags); | |
1687 | /* Don't allow registering multiple times */ | |
1688 | if (!dumper->registered) { | |
1689 | dumper->registered = 1; | |
fb842b00 | 1690 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
1691 | err = 0; |
1692 | } | |
1693 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1694 | ||
1695 | return err; | |
1696 | } | |
1697 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
1698 | ||
1699 | /** | |
1700 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 1701 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1702 | * |
1703 | * Removes a dump device from the system. Returns zero on success and | |
1704 | * %-EINVAL otherwise. | |
1705 | */ | |
1706 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
1707 | { | |
1708 | unsigned long flags; | |
1709 | int err = -EINVAL; | |
1710 | ||
1711 | spin_lock_irqsave(&dump_list_lock, flags); | |
1712 | if (dumper->registered) { | |
1713 | dumper->registered = 0; | |
fb842b00 | 1714 | list_del_rcu(&dumper->list); |
456b565c SK |
1715 | err = 0; |
1716 | } | |
1717 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 1718 | synchronize_rcu(); |
456b565c SK |
1719 | |
1720 | return err; | |
1721 | } | |
1722 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
1723 | ||
456b565c SK |
1724 | /** |
1725 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
1726 | * @reason: the reason (oops, panic etc) for dumping | |
1727 | * | |
1728 | * Iterate through each of the dump devices and call the oops/panic | |
1729 | * callbacks with the log buffer. | |
1730 | */ | |
1731 | void kmsg_dump(enum kmsg_dump_reason reason) | |
1732 | { | |
1733 | unsigned long end; | |
1734 | unsigned chars; | |
1735 | struct kmsg_dumper *dumper; | |
1736 | const char *s1, *s2; | |
1737 | unsigned long l1, l2; | |
1738 | unsigned long flags; | |
1739 | ||
1740 | /* Theoretically, the log could move on after we do this, but | |
1741 | there's not a lot we can do about that. The new messages | |
1742 | will overwrite the start of what we dump. */ | |
07354eb1 | 1743 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
456b565c SK |
1744 | end = log_end & LOG_BUF_MASK; |
1745 | chars = logged_chars; | |
07354eb1 | 1746 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
456b565c | 1747 | |
8c4af38e AK |
1748 | if (chars > end) { |
1749 | s1 = log_buf + log_buf_len - chars + end; | |
1750 | l1 = chars - end; | |
456b565c SK |
1751 | |
1752 | s2 = log_buf; | |
1753 | l2 = end; | |
1754 | } else { | |
1755 | s1 = ""; | |
1756 | l1 = 0; | |
1757 | ||
8c4af38e AK |
1758 | s2 = log_buf + end - chars; |
1759 | l2 = chars; | |
456b565c SK |
1760 | } |
1761 | ||
fb842b00 HY |
1762 | rcu_read_lock(); |
1763 | list_for_each_entry_rcu(dumper, &dump_list, list) | |
456b565c | 1764 | dumper->dump(dumper, reason, s1, l1, s2, l2); |
fb842b00 | 1765 | rcu_read_unlock(); |
456b565c | 1766 | } |
7ef3d2fd | 1767 | #endif |