]>
Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/kernel/printk.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * Modified to make sys_syslog() more flexible: added commands to | |
7 | * return the last 4k of kernel messages, regardless of whether | |
8 | * they've been read or not. Added option to suppress kernel printk's | |
9 | * to the console. Added hook for sending the console messages | |
10 | * elsewhere, in preparation for a serial line console (someday). | |
11 | * Ted Ts'o, 2/11/93. | |
12 | * Modified for sysctl support, 1/8/97, Chris Horn. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 | 15 | * Rewrote bits to get rid of console_lock |
e1f8e874 | 16 | * 01Mar01 Andrew Morton |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
1da177e4 LT |
23 | #include <linux/console.h> |
24 | #include <linux/init.h> | |
bfe8df3d RD |
25 | #include <linux/jiffies.h> |
26 | #include <linux/nmi.h> | |
1da177e4 | 27 | #include <linux/module.h> |
3b9c0410 | 28 | #include <linux/moduleparam.h> |
1da177e4 | 29 | #include <linux/interrupt.h> /* For in_interrupt() */ |
1da177e4 LT |
30 | #include <linux/delay.h> |
31 | #include <linux/smp.h> | |
32 | #include <linux/security.h> | |
33 | #include <linux/bootmem.h> | |
34 | #include <linux/syscalls.h> | |
04d491ab | 35 | #include <linux/kexec.h> |
d37d39ae | 36 | #include <linux/kdb.h> |
3fff4c42 | 37 | #include <linux/ratelimit.h> |
456b565c | 38 | #include <linux/kmsg_dump.h> |
00234592 | 39 | #include <linux/syslog.h> |
034260d6 KC |
40 | #include <linux/cpu.h> |
41 | #include <linux/notifier.h> | |
1da177e4 LT |
42 | |
43 | #include <asm/uaccess.h> | |
44 | ||
076f9776 IM |
45 | /* |
46 | * Architectures can override it: | |
47 | */ | |
e17ba73b | 48 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
076f9776 IM |
49 | { |
50 | } | |
51 | ||
1da177e4 LT |
52 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
53 | ||
54 | /* printk's without a loglevel use this.. */ | |
55 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ | |
56 | ||
57 | /* We show everything that is MORE important than this.. */ | |
58 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
59 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
60 | ||
61 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
62 | ||
63 | int console_printk[4] = { | |
64 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
65 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
66 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
67 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
68 | }; | |
69 | ||
1da177e4 | 70 | /* |
0bbfb7c2 | 71 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
72 | * their unblank() callback or not. So let's export it. |
73 | */ | |
74 | int oops_in_progress; | |
75 | EXPORT_SYMBOL(oops_in_progress); | |
76 | ||
77 | /* | |
78 | * console_sem protects the console_drivers list, and also | |
79 | * provides serialisation for access to the entire console | |
80 | * driver system. | |
81 | */ | |
5b8c4f23 | 82 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 83 | struct console *console_drivers; |
a29d1cfe IM |
84 | EXPORT_SYMBOL_GPL(console_drivers); |
85 | ||
1da177e4 LT |
86 | /* |
87 | * This is used for debugging the mess that is the VT code by | |
88 | * keeping track if we have the console semaphore held. It's | |
89 | * definitely not the perfect debug tool (we don't know if _WE_ | |
90 | * hold it are racing, but it helps tracking those weird code | |
91 | * path in the console code where we end up in places I want | |
92 | * locked without the console sempahore held | |
93 | */ | |
557240b4 | 94 | static int console_locked, console_suspended; |
1da177e4 LT |
95 | |
96 | /* | |
97 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
98 | * It is also used in interesting ways to provide interlocking in | |
99 | * release_console_sem(). | |
100 | */ | |
101 | static DEFINE_SPINLOCK(logbuf_lock); | |
102 | ||
eed4a2ab | 103 | #define LOG_BUF_MASK (log_buf_len-1) |
1da177e4 LT |
104 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
105 | ||
106 | /* | |
107 | * The indices into log_buf are not constrained to log_buf_len - they | |
108 | * must be masked before subscripting | |
109 | */ | |
eed4a2ab DV |
110 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
111 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ | |
112 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
113 | |
114 | /* | |
115 | * Array of consoles built from command line options (console=) | |
116 | */ | |
117 | struct console_cmdline | |
118 | { | |
119 | char name[8]; /* Name of the driver */ | |
120 | int index; /* Minor dev. to use */ | |
121 | char *options; /* Options for the driver */ | |
f7511d5f ST |
122 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
123 | char *brl_options; /* Options for braille driver */ | |
124 | #endif | |
1da177e4 LT |
125 | }; |
126 | ||
127 | #define MAX_CMDLINECONSOLES 8 | |
128 | ||
129 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
130 | static int selected_console = -1; | |
131 | static int preferred_console = -1; | |
9e124fe1 MA |
132 | int console_set_on_cmdline; |
133 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
134 | |
135 | /* Flag: console code may call schedule() */ | |
136 | static int console_may_schedule; | |
137 | ||
d59745ce MM |
138 | #ifdef CONFIG_PRINTK |
139 | ||
140 | static char __log_buf[__LOG_BUF_LEN]; | |
141 | static char *log_buf = __log_buf; | |
142 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 143 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
cea83886 | 144 | static int saved_console_loglevel = -1; |
d59745ce | 145 | |
04d491ab NH |
146 | #ifdef CONFIG_KEXEC |
147 | /* | |
148 | * This appends the listed symbols to /proc/vmcoreinfo | |
149 | * | |
150 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
151 | * obtain access to symbols that are otherwise very difficult to locate. These | |
152 | * symbols are specifically used so that utilities can access and extract the | |
153 | * dmesg log from a vmcore file after a crash. | |
154 | */ | |
155 | void log_buf_kexec_setup(void) | |
156 | { | |
157 | VMCOREINFO_SYMBOL(log_buf); | |
158 | VMCOREINFO_SYMBOL(log_end); | |
159 | VMCOREINFO_SYMBOL(log_buf_len); | |
160 | VMCOREINFO_SYMBOL(logged_chars); | |
161 | } | |
162 | #endif | |
163 | ||
1da177e4 LT |
164 | static int __init log_buf_len_setup(char *str) |
165 | { | |
eed4a2ab | 166 | unsigned size = memparse(str, &str); |
1da177e4 LT |
167 | unsigned long flags; |
168 | ||
169 | if (size) | |
170 | size = roundup_pow_of_two(size); | |
171 | if (size > log_buf_len) { | |
eed4a2ab | 172 | unsigned start, dest_idx, offset; |
40dc5651 | 173 | char *new_log_buf; |
1da177e4 LT |
174 | |
175 | new_log_buf = alloc_bootmem(size); | |
176 | if (!new_log_buf) { | |
40dc5651 | 177 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
178 | goto out; |
179 | } | |
180 | ||
181 | spin_lock_irqsave(&logbuf_lock, flags); | |
182 | log_buf_len = size; | |
183 | log_buf = new_log_buf; | |
184 | ||
185 | offset = start = min(con_start, log_start); | |
186 | dest_idx = 0; | |
187 | while (start != log_end) { | |
188 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
189 | start++; | |
190 | dest_idx++; | |
191 | } | |
192 | log_start -= offset; | |
193 | con_start -= offset; | |
194 | log_end -= offset; | |
195 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
196 | ||
40dc5651 | 197 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
198 | } |
199 | out: | |
1da177e4 LT |
200 | return 1; |
201 | } | |
202 | ||
203 | __setup("log_buf_len=", log_buf_len_setup); | |
204 | ||
bfe8df3d RD |
205 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
206 | ||
674dff65 | 207 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 208 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
209 | |
210 | static int __init boot_delay_setup(char *str) | |
211 | { | |
212 | unsigned long lpj; | |
bfe8df3d RD |
213 | |
214 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
215 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
216 | ||
217 | get_option(&str, &boot_delay); | |
218 | if (boot_delay > 10 * 1000) | |
219 | boot_delay = 0; | |
220 | ||
3a3b6ed2 DY |
221 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
222 | "HZ: %d, loops_per_msec: %llu\n", | |
223 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
bfe8df3d RD |
224 | return 1; |
225 | } | |
226 | __setup("boot_delay=", boot_delay_setup); | |
227 | ||
228 | static void boot_delay_msec(void) | |
229 | { | |
230 | unsigned long long k; | |
231 | unsigned long timeout; | |
232 | ||
233 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
234 | return; | |
235 | ||
3a3b6ed2 | 236 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
237 | |
238 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
239 | while (k) { | |
240 | k--; | |
241 | cpu_relax(); | |
242 | /* | |
243 | * use (volatile) jiffies to prevent | |
244 | * compiler reduction; loop termination via jiffies | |
245 | * is secondary and may or may not happen. | |
246 | */ | |
247 | if (time_after(jiffies, timeout)) | |
248 | break; | |
249 | touch_nmi_watchdog(); | |
250 | } | |
251 | } | |
252 | #else | |
253 | static inline void boot_delay_msec(void) | |
254 | { | |
255 | } | |
256 | #endif | |
257 | ||
eaf06b24 DR |
258 | #ifdef CONFIG_SECURITY_DMESG_RESTRICT |
259 | int dmesg_restrict = 1; | |
260 | #else | |
261 | int dmesg_restrict; | |
262 | #endif | |
263 | ||
00234592 | 264 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
1da177e4 | 265 | { |
eed4a2ab | 266 | unsigned i, j, limit, count; |
1da177e4 LT |
267 | int do_clear = 0; |
268 | char c; | |
269 | int error = 0; | |
270 | ||
12b3052c EP |
271 | /* |
272 | * If this is from /proc/kmsg we only do the capabilities checks | |
273 | * at open time. | |
274 | */ | |
275 | if (type == SYSLOG_ACTION_OPEN || !from_file) { | |
276 | if (dmesg_restrict && !capable(CAP_SYS_ADMIN)) | |
277 | return -EPERM; | |
278 | if ((type != SYSLOG_ACTION_READ_ALL && | |
279 | type != SYSLOG_ACTION_SIZE_BUFFER) && | |
280 | !capable(CAP_SYS_ADMIN)) | |
281 | return -EPERM; | |
282 | } | |
283 | ||
284 | error = security_syslog(type); | |
1da177e4 LT |
285 | if (error) |
286 | return error; | |
287 | ||
288 | switch (type) { | |
d78ca3cd | 289 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 290 | break; |
d78ca3cd | 291 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 292 | break; |
d78ca3cd | 293 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 LT |
294 | error = -EINVAL; |
295 | if (!buf || len < 0) | |
296 | goto out; | |
297 | error = 0; | |
298 | if (!len) | |
299 | goto out; | |
300 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
301 | error = -EFAULT; | |
302 | goto out; | |
303 | } | |
40dc5651 JJ |
304 | error = wait_event_interruptible(log_wait, |
305 | (log_start - log_end)); | |
1da177e4 LT |
306 | if (error) |
307 | goto out; | |
308 | i = 0; | |
309 | spin_lock_irq(&logbuf_lock); | |
310 | while (!error && (log_start != log_end) && i < len) { | |
311 | c = LOG_BUF(log_start); | |
312 | log_start++; | |
313 | spin_unlock_irq(&logbuf_lock); | |
314 | error = __put_user(c,buf); | |
315 | buf++; | |
316 | i++; | |
317 | cond_resched(); | |
318 | spin_lock_irq(&logbuf_lock); | |
319 | } | |
320 | spin_unlock_irq(&logbuf_lock); | |
321 | if (!error) | |
322 | error = i; | |
323 | break; | |
d78ca3cd KC |
324 | /* Read/clear last kernel messages */ |
325 | case SYSLOG_ACTION_READ_CLEAR: | |
40dc5651 | 326 | do_clear = 1; |
1da177e4 | 327 | /* FALL THRU */ |
d78ca3cd KC |
328 | /* Read last kernel messages */ |
329 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 LT |
330 | error = -EINVAL; |
331 | if (!buf || len < 0) | |
332 | goto out; | |
333 | error = 0; | |
334 | if (!len) | |
335 | goto out; | |
336 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
337 | error = -EFAULT; | |
338 | goto out; | |
339 | } | |
340 | count = len; | |
341 | if (count > log_buf_len) | |
342 | count = log_buf_len; | |
343 | spin_lock_irq(&logbuf_lock); | |
344 | if (count > logged_chars) | |
345 | count = logged_chars; | |
346 | if (do_clear) | |
347 | logged_chars = 0; | |
348 | limit = log_end; | |
349 | /* | |
350 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 351 | * printk() could overwrite the messages |
1da177e4 LT |
352 | * we try to copy to user space. Therefore |
353 | * the messages are copied in reverse. <manfreds> | |
354 | */ | |
40dc5651 | 355 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
356 | j = limit-1-i; |
357 | if (j + log_buf_len < log_end) | |
358 | break; | |
359 | c = LOG_BUF(j); | |
360 | spin_unlock_irq(&logbuf_lock); | |
361 | error = __put_user(c,&buf[count-1-i]); | |
362 | cond_resched(); | |
363 | spin_lock_irq(&logbuf_lock); | |
364 | } | |
365 | spin_unlock_irq(&logbuf_lock); | |
366 | if (error) | |
367 | break; | |
368 | error = i; | |
40dc5651 | 369 | if (i != count) { |
1da177e4 LT |
370 | int offset = count-error; |
371 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 372 | for (i = 0; i < error; i++) { |
1da177e4 LT |
373 | if (__get_user(c,&buf[i+offset]) || |
374 | __put_user(c,&buf[i])) { | |
375 | error = -EFAULT; | |
376 | break; | |
377 | } | |
378 | cond_resched(); | |
379 | } | |
380 | } | |
381 | break; | |
d78ca3cd KC |
382 | /* Clear ring buffer */ |
383 | case SYSLOG_ACTION_CLEAR: | |
1da177e4 LT |
384 | logged_chars = 0; |
385 | break; | |
d78ca3cd KC |
386 | /* Disable logging to console */ |
387 | case SYSLOG_ACTION_CONSOLE_OFF: | |
1aaad49e FP |
388 | if (saved_console_loglevel == -1) |
389 | saved_console_loglevel = console_loglevel; | |
1da177e4 LT |
390 | console_loglevel = minimum_console_loglevel; |
391 | break; | |
d78ca3cd KC |
392 | /* Enable logging to console */ |
393 | case SYSLOG_ACTION_CONSOLE_ON: | |
1aaad49e FP |
394 | if (saved_console_loglevel != -1) { |
395 | console_loglevel = saved_console_loglevel; | |
396 | saved_console_loglevel = -1; | |
397 | } | |
1da177e4 | 398 | break; |
d78ca3cd KC |
399 | /* Set level of messages printed to console */ |
400 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 LT |
401 | error = -EINVAL; |
402 | if (len < 1 || len > 8) | |
403 | goto out; | |
404 | if (len < minimum_console_loglevel) | |
405 | len = minimum_console_loglevel; | |
406 | console_loglevel = len; | |
1aaad49e FP |
407 | /* Implicitly re-enable logging to console */ |
408 | saved_console_loglevel = -1; | |
1da177e4 LT |
409 | error = 0; |
410 | break; | |
d78ca3cd KC |
411 | /* Number of chars in the log buffer */ |
412 | case SYSLOG_ACTION_SIZE_UNREAD: | |
1da177e4 LT |
413 | error = log_end - log_start; |
414 | break; | |
d78ca3cd KC |
415 | /* Size of the log buffer */ |
416 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
417 | error = log_buf_len; |
418 | break; | |
419 | default: | |
420 | error = -EINVAL; | |
421 | break; | |
422 | } | |
423 | out: | |
424 | return error; | |
425 | } | |
426 | ||
1e7bfb21 | 427 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 428 | { |
00234592 | 429 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
1da177e4 LT |
430 | } |
431 | ||
67fc4e0c JW |
432 | #ifdef CONFIG_KGDB_KDB |
433 | /* kdb dmesg command needs access to the syslog buffer. do_syslog() | |
434 | * uses locks so it cannot be used during debugging. Just tell kdb | |
435 | * where the start and end of the physical and logical logs are. This | |
436 | * is equivalent to do_syslog(3). | |
437 | */ | |
438 | void kdb_syslog_data(char *syslog_data[4]) | |
439 | { | |
440 | syslog_data[0] = log_buf; | |
441 | syslog_data[1] = log_buf + log_buf_len; | |
442 | syslog_data[2] = log_buf + log_end - | |
443 | (logged_chars < log_buf_len ? logged_chars : log_buf_len); | |
444 | syslog_data[3] = log_buf + log_end; | |
445 | } | |
446 | #endif /* CONFIG_KGDB_KDB */ | |
447 | ||
1da177e4 LT |
448 | /* |
449 | * Call the console drivers on a range of log_buf | |
450 | */ | |
eed4a2ab | 451 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
452 | { |
453 | struct console *con; | |
454 | ||
4d091611 | 455 | for_each_console(con) { |
76a8ad29 ME |
456 | if ((con->flags & CON_ENABLED) && con->write && |
457 | (cpu_online(smp_processor_id()) || | |
458 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
459 | con->write(con, &LOG_BUF(start), end - start); |
460 | } | |
461 | } | |
462 | ||
79290822 IM |
463 | static int __read_mostly ignore_loglevel; |
464 | ||
99eea6a1 | 465 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
466 | { |
467 | ignore_loglevel = 1; | |
468 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
469 | ||
c4772d99 | 470 | return 0; |
79290822 IM |
471 | } |
472 | ||
c4772d99 | 473 | early_param("ignore_loglevel", ignore_loglevel_setup); |
79290822 | 474 | |
1da177e4 LT |
475 | /* |
476 | * Write out chars from start to end - 1 inclusive | |
477 | */ | |
eed4a2ab DV |
478 | static void _call_console_drivers(unsigned start, |
479 | unsigned end, int msg_log_level) | |
1da177e4 | 480 | { |
79290822 | 481 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
482 | console_drivers && start != end) { |
483 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
484 | /* wrapped write */ | |
485 | __call_console_drivers(start & LOG_BUF_MASK, | |
486 | log_buf_len); | |
487 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
488 | } else { | |
489 | __call_console_drivers(start, end); | |
490 | } | |
491 | } | |
492 | } | |
493 | ||
494 | /* | |
495 | * Call the console drivers, asking them to write out | |
496 | * log_buf[start] to log_buf[end - 1]. | |
497 | * The console_sem must be held. | |
498 | */ | |
eed4a2ab | 499 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 500 | { |
eed4a2ab | 501 | unsigned cur_index, start_print; |
1da177e4 LT |
502 | static int msg_level = -1; |
503 | ||
eed4a2ab | 504 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
505 | |
506 | cur_index = start; | |
507 | start_print = start; | |
508 | while (cur_index != end) { | |
40dc5651 JJ |
509 | if (msg_level < 0 && ((end - cur_index) > 2) && |
510 | LOG_BUF(cur_index + 0) == '<' && | |
511 | LOG_BUF(cur_index + 1) >= '0' && | |
512 | LOG_BUF(cur_index + 1) <= '7' && | |
513 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
514 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
515 | cur_index += 3; | |
516 | start_print = cur_index; | |
517 | } | |
518 | while (cur_index != end) { | |
519 | char c = LOG_BUF(cur_index); | |
1da177e4 | 520 | |
40dc5651 | 521 | cur_index++; |
1da177e4 LT |
522 | if (c == '\n') { |
523 | if (msg_level < 0) { | |
524 | /* | |
525 | * printk() has already given us loglevel tags in | |
526 | * the buffer. This code is here in case the | |
527 | * log buffer has wrapped right round and scribbled | |
528 | * on those tags | |
529 | */ | |
530 | msg_level = default_message_loglevel; | |
531 | } | |
532 | _call_console_drivers(start_print, cur_index, msg_level); | |
533 | msg_level = -1; | |
534 | start_print = cur_index; | |
535 | break; | |
536 | } | |
537 | } | |
538 | } | |
539 | _call_console_drivers(start_print, end, msg_level); | |
540 | } | |
541 | ||
542 | static void emit_log_char(char c) | |
543 | { | |
544 | LOG_BUF(log_end) = c; | |
545 | log_end++; | |
546 | if (log_end - log_start > log_buf_len) | |
547 | log_start = log_end - log_buf_len; | |
548 | if (log_end - con_start > log_buf_len) | |
549 | con_start = log_end - log_buf_len; | |
550 | if (logged_chars < log_buf_len) | |
551 | logged_chars++; | |
552 | } | |
553 | ||
554 | /* | |
555 | * Zap console related locks when oopsing. Only zap at most once | |
556 | * every 10 seconds, to leave time for slow consoles to print a | |
557 | * full oops. | |
558 | */ | |
559 | static void zap_locks(void) | |
560 | { | |
561 | static unsigned long oops_timestamp; | |
562 | ||
563 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 564 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
565 | return; |
566 | ||
567 | oops_timestamp = jiffies; | |
568 | ||
569 | /* If a crash is occurring, make sure we can't deadlock */ | |
570 | spin_lock_init(&logbuf_lock); | |
571 | /* And make sure that we print immediately */ | |
5b8c4f23 | 572 | sema_init(&console_sem, 1); |
1da177e4 LT |
573 | } |
574 | ||
575 | #if defined(CONFIG_PRINTK_TIME) | |
576 | static int printk_time = 1; | |
577 | #else | |
578 | static int printk_time = 0; | |
579 | #endif | |
e84845c4 | 580 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 581 | |
76a8ad29 ME |
582 | /* Check if we have any console registered that can be called early in boot. */ |
583 | static int have_callable_console(void) | |
584 | { | |
585 | struct console *con; | |
586 | ||
4d091611 | 587 | for_each_console(con) |
76a8ad29 ME |
588 | if (con->flags & CON_ANYTIME) |
589 | return 1; | |
590 | ||
591 | return 0; | |
592 | } | |
593 | ||
ddad86c2 MW |
594 | /** |
595 | * printk - print a kernel message | |
596 | * @fmt: format string | |
597 | * | |
72fd4a35 | 598 | * This is printk(). It can be called from any context. We want it to work. |
40dc5651 | 599 | * |
1da177e4 LT |
600 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
601 | * call the console drivers. If we fail to get the semaphore we place the output | |
602 | * into the log buffer and return. The current holder of the console_sem will | |
603 | * notice the new output in release_console_sem() and will send it to the | |
604 | * consoles before releasing the semaphore. | |
605 | * | |
606 | * One effect of this deferred printing is that code which calls printk() and | |
607 | * then changes console_loglevel may break. This is because console_loglevel | |
608 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
609 | * |
610 | * See also: | |
611 | * printf(3) | |
20036fdc AK |
612 | * |
613 | * See the vsnprintf() documentation for format string extensions over C99. | |
1da177e4 | 614 | */ |
d59745ce | 615 | |
1da177e4 LT |
616 | asmlinkage int printk(const char *fmt, ...) |
617 | { | |
618 | va_list args; | |
619 | int r; | |
620 | ||
d37d39ae JW |
621 | #ifdef CONFIG_KGDB_KDB |
622 | if (unlikely(kdb_trap_printk)) { | |
623 | va_start(args, fmt); | |
624 | r = vkdb_printf(fmt, args); | |
625 | va_end(args); | |
626 | return r; | |
627 | } | |
628 | #endif | |
1da177e4 LT |
629 | va_start(args, fmt); |
630 | r = vprintk(fmt, args); | |
631 | va_end(args); | |
632 | ||
633 | return r; | |
634 | } | |
635 | ||
fe21773d DH |
636 | /* cpu currently holding logbuf_lock */ |
637 | static volatile unsigned int printk_cpu = UINT_MAX; | |
638 | ||
266c2e0a LT |
639 | /* |
640 | * Can we actually use the console at this time on this cpu? | |
641 | * | |
642 | * Console drivers may assume that per-cpu resources have | |
643 | * been allocated. So unless they're explicitly marked as | |
644 | * being able to cope (CON_ANYTIME) don't call them until | |
645 | * this CPU is officially up. | |
646 | */ | |
647 | static inline int can_use_console(unsigned int cpu) | |
648 | { | |
649 | return cpu_online(cpu) || have_callable_console(); | |
650 | } | |
651 | ||
652 | /* | |
653 | * Try to get console ownership to actually show the kernel | |
654 | * messages from a 'printk'. Return true (and with the | |
655 | * console_semaphore held, and 'console_locked' set) if it | |
656 | * is successful, false otherwise. | |
657 | * | |
658 | * This gets called with the 'logbuf_lock' spinlock held and | |
659 | * interrupts disabled. It should return with 'lockbuf_lock' | |
660 | * released but interrupts still disabled. | |
661 | */ | |
662 | static int acquire_console_semaphore_for_printk(unsigned int cpu) | |
8155c02a | 663 | __releases(&logbuf_lock) |
266c2e0a LT |
664 | { |
665 | int retval = 0; | |
666 | ||
093a07e2 LT |
667 | if (!try_acquire_console_sem()) { |
668 | retval = 1; | |
669 | ||
670 | /* | |
671 | * If we can't use the console, we need to release | |
672 | * the console semaphore by hand to avoid flushing | |
673 | * the buffer. We need to hold the console semaphore | |
674 | * in order to do this test safely. | |
675 | */ | |
676 | if (!can_use_console(cpu)) { | |
677 | console_locked = 0; | |
678 | up(&console_sem); | |
679 | retval = 0; | |
680 | } | |
681 | } | |
266c2e0a LT |
682 | printk_cpu = UINT_MAX; |
683 | spin_unlock(&logbuf_lock); | |
684 | return retval; | |
685 | } | |
3b8945e8 TH |
686 | static const char recursion_bug_msg [] = |
687 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
688 | static int recursion_bug; | |
edb123e1 | 689 | static int new_text_line = 1; |
3b8945e8 | 690 | static char printk_buf[1024]; |
32a76006 | 691 | |
af91322e DY |
692 | int printk_delay_msec __read_mostly; |
693 | ||
694 | static inline void printk_delay(void) | |
695 | { | |
696 | if (unlikely(printk_delay_msec)) { | |
697 | int m = printk_delay_msec; | |
698 | ||
699 | while (m--) { | |
700 | mdelay(1); | |
701 | touch_nmi_watchdog(); | |
702 | } | |
703 | } | |
704 | } | |
705 | ||
1da177e4 LT |
706 | asmlinkage int vprintk(const char *fmt, va_list args) |
707 | { | |
32a76006 | 708 | int printed_len = 0; |
09159308 | 709 | int current_log_level = default_message_loglevel; |
ac60ad74 | 710 | unsigned long flags; |
32a76006 | 711 | int this_cpu; |
1da177e4 | 712 | char *p; |
1da177e4 | 713 | |
bfe8df3d | 714 | boot_delay_msec(); |
af91322e | 715 | printk_delay(); |
bfe8df3d | 716 | |
fe21773d | 717 | preempt_disable(); |
1da177e4 | 718 | /* This stops the holder of console_sem just where we want him */ |
1efc5da3 | 719 | raw_local_irq_save(flags); |
32a76006 IM |
720 | this_cpu = smp_processor_id(); |
721 | ||
722 | /* | |
723 | * Ouch, printk recursed into itself! | |
724 | */ | |
725 | if (unlikely(printk_cpu == this_cpu)) { | |
726 | /* | |
727 | * If a crash is occurring during printk() on this CPU, | |
728 | * then try to get the crash message out but make sure | |
729 | * we can't deadlock. Otherwise just return to avoid the | |
730 | * recursion and return - but flag the recursion so that | |
731 | * it can be printed at the next appropriate moment: | |
732 | */ | |
733 | if (!oops_in_progress) { | |
3b8945e8 | 734 | recursion_bug = 1; |
32a76006 IM |
735 | goto out_restore_irqs; |
736 | } | |
737 | zap_locks(); | |
738 | } | |
739 | ||
a0f1ccfd IM |
740 | lockdep_off(); |
741 | spin_lock(&logbuf_lock); | |
32a76006 | 742 | printk_cpu = this_cpu; |
1da177e4 | 743 | |
3b8945e8 TH |
744 | if (recursion_bug) { |
745 | recursion_bug = 0; | |
746 | strcpy(printk_buf, recursion_bug_msg); | |
26cc271d | 747 | printed_len = strlen(recursion_bug_msg); |
32a76006 | 748 | } |
1da177e4 | 749 | /* Emit the output into the temporary buffer */ |
32a76006 | 750 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 751 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 752 | |
ac60ad74 | 753 | |
5fd29d6c LT |
754 | p = printk_buf; |
755 | ||
756 | /* Do we have a loglevel in the string? */ | |
757 | if (p[0] == '<') { | |
758 | unsigned char c = p[1]; | |
759 | if (c && p[2] == '>') { | |
760 | switch (c) { | |
761 | case '0' ... '7': /* loglevel */ | |
762 | current_log_level = c - '0'; | |
e28d7137 LT |
763 | /* Fallthrough - make sure we're on a new line */ |
764 | case 'd': /* KERN_DEFAULT */ | |
5fd29d6c LT |
765 | if (!new_text_line) { |
766 | emit_log_char('\n'); | |
767 | new_text_line = 1; | |
768 | } | |
769 | /* Fallthrough - skip the loglevel */ | |
770 | case 'c': /* KERN_CONT */ | |
771 | p += 3; | |
772 | break; | |
773 | } | |
774 | } | |
775 | } | |
776 | ||
1da177e4 LT |
777 | /* |
778 | * Copy the output into log_buf. If the caller didn't provide | |
779 | * appropriate log level tags, we insert them here | |
780 | */ | |
5fd29d6c | 781 | for ( ; *p; p++) { |
ac60ad74 | 782 | if (new_text_line) { |
ac60ad74 NA |
783 | /* Always output the token */ |
784 | emit_log_char('<'); | |
785 | emit_log_char(current_log_level + '0'); | |
786 | emit_log_char('>'); | |
787 | printed_len += 3; | |
788 | new_text_line = 0; | |
789 | ||
1da177e4 | 790 | if (printk_time) { |
ac60ad74 | 791 | /* Follow the token with the time */ |
1da177e4 LT |
792 | char tbuf[50], *tp; |
793 | unsigned tlen; | |
794 | unsigned long long t; | |
795 | unsigned long nanosec_rem; | |
796 | ||
326e96b9 | 797 | t = cpu_clock(printk_cpu); |
1da177e4 | 798 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
799 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
800 | (unsigned long) t, | |
801 | nanosec_rem / 1000); | |
1da177e4 LT |
802 | |
803 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
804 | emit_log_char(*tp); | |
025510cd | 805 | printed_len += tlen; |
1da177e4 | 806 | } |
ac60ad74 | 807 | |
1da177e4 LT |
808 | if (!*p) |
809 | break; | |
810 | } | |
ac60ad74 | 811 | |
1da177e4 LT |
812 | emit_log_char(*p); |
813 | if (*p == '\n') | |
ac60ad74 | 814 | new_text_line = 1; |
1da177e4 LT |
815 | } |
816 | ||
266c2e0a LT |
817 | /* |
818 | * Try to acquire and then immediately release the | |
819 | * console semaphore. The release will do all the | |
820 | * actual magic (print out buffers, wake up klogd, | |
821 | * etc). | |
822 | * | |
823 | * The acquire_console_semaphore_for_printk() function | |
824 | * will release 'logbuf_lock' regardless of whether it | |
825 | * actually gets the semaphore or not. | |
826 | */ | |
827 | if (acquire_console_semaphore_for_printk(this_cpu)) | |
828 | release_console_sem(); | |
76a8ad29 | 829 | |
266c2e0a | 830 | lockdep_on(); |
32a76006 | 831 | out_restore_irqs: |
266c2e0a | 832 | raw_local_irq_restore(flags); |
76a8ad29 | 833 | |
fe21773d | 834 | preempt_enable(); |
1da177e4 LT |
835 | return printed_len; |
836 | } | |
837 | EXPORT_SYMBOL(printk); | |
838 | EXPORT_SYMBOL(vprintk); | |
839 | ||
d59745ce MM |
840 | #else |
841 | ||
eed4a2ab | 842 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
843 | { |
844 | } | |
d59745ce MM |
845 | |
846 | #endif | |
847 | ||
f7511d5f ST |
848 | static int __add_preferred_console(char *name, int idx, char *options, |
849 | char *brl_options) | |
850 | { | |
851 | struct console_cmdline *c; | |
852 | int i; | |
853 | ||
854 | /* | |
855 | * See if this tty is not yet registered, and | |
856 | * if we have a slot free. | |
857 | */ | |
858 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
859 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
860 | console_cmdline[i].index == idx) { | |
861 | if (!brl_options) | |
862 | selected_console = i; | |
863 | return 0; | |
864 | } | |
865 | if (i == MAX_CMDLINECONSOLES) | |
866 | return -E2BIG; | |
867 | if (!brl_options) | |
868 | selected_console = i; | |
869 | c = &console_cmdline[i]; | |
870 | strlcpy(c->name, name, sizeof(c->name)); | |
871 | c->options = options; | |
872 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
873 | c->brl_options = brl_options; | |
874 | #endif | |
875 | c->index = idx; | |
876 | return 0; | |
877 | } | |
2ea1c539 JB |
878 | /* |
879 | * Set up a list of consoles. Called from init/main.c | |
880 | */ | |
881 | static int __init console_setup(char *str) | |
882 | { | |
eaa944af | 883 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 884 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
885 | int idx; |
886 | ||
f7511d5f ST |
887 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
888 | if (!memcmp(str, "brl,", 4)) { | |
889 | brl_options = ""; | |
890 | str += 4; | |
891 | } else if (!memcmp(str, "brl=", 4)) { | |
892 | brl_options = str + 4; | |
893 | str = strchr(brl_options, ','); | |
894 | if (!str) { | |
895 | printk(KERN_ERR "need port name after brl=\n"); | |
896 | return 1; | |
897 | } | |
898 | *(str++) = 0; | |
899 | } | |
900 | #endif | |
901 | ||
2ea1c539 JB |
902 | /* |
903 | * Decode str into name, index, options. | |
904 | */ | |
905 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
906 | strcpy(buf, "ttyS"); |
907 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 908 | } else { |
eaa944af | 909 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 910 | } |
eaa944af | 911 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
912 | if ((options = strchr(str, ',')) != NULL) |
913 | *(options++) = 0; | |
914 | #ifdef __sparc__ | |
915 | if (!strcmp(str, "ttya")) | |
eaa944af | 916 | strcpy(buf, "ttyS0"); |
2ea1c539 | 917 | if (!strcmp(str, "ttyb")) |
eaa944af | 918 | strcpy(buf, "ttyS1"); |
2ea1c539 | 919 | #endif |
eaa944af | 920 | for (s = buf; *s; s++) |
2ea1c539 JB |
921 | if ((*s >= '0' && *s <= '9') || *s == ',') |
922 | break; | |
923 | idx = simple_strtoul(s, NULL, 10); | |
924 | *s = 0; | |
925 | ||
f7511d5f | 926 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 927 | console_set_on_cmdline = 1; |
2ea1c539 JB |
928 | return 1; |
929 | } | |
930 | __setup("console=", console_setup); | |
931 | ||
3c0547ba MM |
932 | /** |
933 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
934 | * @name: device name |
935 | * @idx: device index | |
936 | * @options: options for this console | |
3c0547ba MM |
937 | * |
938 | * The last preferred console added will be used for kernel messages | |
939 | * and stdin/out/err for init. Normally this is used by console_setup | |
940 | * above to handle user-supplied console arguments; however it can also | |
941 | * be used by arch-specific code either to override the user or more | |
942 | * commonly to provide a default console (ie from PROM variables) when | |
943 | * the user has not supplied one. | |
944 | */ | |
fb445ee5 | 945 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 946 | { |
f7511d5f | 947 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
948 | } |
949 | ||
b6b1d877 | 950 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
951 | { |
952 | struct console_cmdline *c; | |
953 | int i; | |
954 | ||
955 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
956 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
957 | console_cmdline[i].index == idx) { | |
958 | c = &console_cmdline[i]; | |
f735295b | 959 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
960 | c->name[sizeof(c->name) - 1] = 0; |
961 | c->options = options; | |
962 | c->index = idx_new; | |
963 | return i; | |
964 | } | |
965 | /* not found */ | |
966 | return -1; | |
967 | } | |
968 | ||
8f4ce8c3 AS |
969 | int console_suspend_enabled = 1; |
970 | EXPORT_SYMBOL(console_suspend_enabled); | |
971 | ||
972 | static int __init console_suspend_disable(char *str) | |
973 | { | |
974 | console_suspend_enabled = 0; | |
975 | return 1; | |
976 | } | |
977 | __setup("no_console_suspend", console_suspend_disable); | |
978 | ||
557240b4 LT |
979 | /** |
980 | * suspend_console - suspend the console subsystem | |
981 | * | |
982 | * This disables printk() while we go into suspend states | |
983 | */ | |
984 | void suspend_console(void) | |
985 | { | |
8f4ce8c3 AS |
986 | if (!console_suspend_enabled) |
987 | return; | |
0d63081d | 988 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
557240b4 LT |
989 | acquire_console_sem(); |
990 | console_suspended = 1; | |
403f3075 | 991 | up(&console_sem); |
557240b4 LT |
992 | } |
993 | ||
994 | void resume_console(void) | |
995 | { | |
8f4ce8c3 AS |
996 | if (!console_suspend_enabled) |
997 | return; | |
403f3075 | 998 | down(&console_sem); |
557240b4 LT |
999 | console_suspended = 0; |
1000 | release_console_sem(); | |
1001 | } | |
1002 | ||
034260d6 KC |
1003 | /** |
1004 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
1005 | * @self: notifier struct | |
1006 | * @action: CPU hotplug event | |
1007 | * @hcpu: unused | |
1008 | * | |
1009 | * If printk() is called from a CPU that is not online yet, the messages | |
1010 | * will be spooled but will not show up on the console. This function is | |
1011 | * called when a new CPU comes online (or fails to come up), and ensures | |
1012 | * that any such output gets printed. | |
1013 | */ | |
1014 | static int __cpuinit console_cpu_notify(struct notifier_block *self, | |
1015 | unsigned long action, void *hcpu) | |
1016 | { | |
1017 | switch (action) { | |
1018 | case CPU_ONLINE: | |
1019 | case CPU_DEAD: | |
1020 | case CPU_DYING: | |
1021 | case CPU_DOWN_FAILED: | |
1022 | case CPU_UP_CANCELED: | |
1023 | acquire_console_sem(); | |
1024 | release_console_sem(); | |
1025 | } | |
1026 | return NOTIFY_OK; | |
1027 | } | |
1028 | ||
1da177e4 LT |
1029 | /** |
1030 | * acquire_console_sem - lock the console system for exclusive use. | |
1031 | * | |
1032 | * Acquires a semaphore which guarantees that the caller has | |
1033 | * exclusive access to the console system and the console_drivers list. | |
1034 | * | |
1035 | * Can sleep, returns nothing. | |
1036 | */ | |
1037 | void acquire_console_sem(void) | |
1038 | { | |
8abd8e29 | 1039 | BUG_ON(in_interrupt()); |
1da177e4 | 1040 | down(&console_sem); |
403f3075 AH |
1041 | if (console_suspended) |
1042 | return; | |
1da177e4 LT |
1043 | console_locked = 1; |
1044 | console_may_schedule = 1; | |
1045 | } | |
1046 | EXPORT_SYMBOL(acquire_console_sem); | |
1047 | ||
1048 | int try_acquire_console_sem(void) | |
1049 | { | |
1050 | if (down_trylock(&console_sem)) | |
1051 | return -1; | |
403f3075 AH |
1052 | if (console_suspended) { |
1053 | up(&console_sem); | |
1054 | return -1; | |
1055 | } | |
1da177e4 LT |
1056 | console_locked = 1; |
1057 | console_may_schedule = 0; | |
1058 | return 0; | |
1059 | } | |
1060 | EXPORT_SYMBOL(try_acquire_console_sem); | |
1061 | ||
1062 | int is_console_locked(void) | |
1063 | { | |
1064 | return console_locked; | |
1065 | } | |
1da177e4 | 1066 | |
b845b517 PZ |
1067 | static DEFINE_PER_CPU(int, printk_pending); |
1068 | ||
1069 | void printk_tick(void) | |
e3e8a75d | 1070 | { |
40dc11ff ED |
1071 | if (__this_cpu_read(printk_pending)) { |
1072 | __this_cpu_write(printk_pending, 0); | |
e3e8a75d | 1073 | wake_up_interruptible(&log_wait); |
b845b517 PZ |
1074 | } |
1075 | } | |
1076 | ||
1077 | int printk_needs_cpu(int cpu) | |
1078 | { | |
40dc11ff | 1079 | if (cpu_is_offline(cpu)) |
61ab2544 | 1080 | printk_tick(); |
40dc11ff | 1081 | return __this_cpu_read(printk_pending); |
b845b517 PZ |
1082 | } |
1083 | ||
1084 | void wake_up_klogd(void) | |
1085 | { | |
1086 | if (waitqueue_active(&log_wait)) | |
49f41383 | 1087 | this_cpu_write(printk_pending, 1); |
e3e8a75d KK |
1088 | } |
1089 | ||
1da177e4 LT |
1090 | /** |
1091 | * release_console_sem - unlock the console system | |
1092 | * | |
1093 | * Releases the semaphore which the caller holds on the console system | |
1094 | * and the console driver list. | |
1095 | * | |
1096 | * While the semaphore was held, console output may have been buffered | |
1097 | * by printk(). If this is the case, release_console_sem() emits | |
1098 | * the output prior to releasing the semaphore. | |
1099 | * | |
1100 | * If there is output waiting for klogd, we wake it up. | |
1101 | * | |
1102 | * release_console_sem() may be called from any context. | |
1103 | */ | |
1104 | void release_console_sem(void) | |
1105 | { | |
1106 | unsigned long flags; | |
eed4a2ab DV |
1107 | unsigned _con_start, _log_end; |
1108 | unsigned wake_klogd = 0; | |
1da177e4 | 1109 | |
557240b4 | 1110 | if (console_suspended) { |
403f3075 | 1111 | up(&console_sem); |
557240b4 LT |
1112 | return; |
1113 | } | |
78944e54 AD |
1114 | |
1115 | console_may_schedule = 0; | |
1116 | ||
1da177e4 LT |
1117 | for ( ; ; ) { |
1118 | spin_lock_irqsave(&logbuf_lock, flags); | |
1119 | wake_klogd |= log_start - log_end; | |
1120 | if (con_start == log_end) | |
1121 | break; /* Nothing to print */ | |
1122 | _con_start = con_start; | |
1123 | _log_end = log_end; | |
1124 | con_start = log_end; /* Flush */ | |
1125 | spin_unlock(&logbuf_lock); | |
81d68a96 | 1126 | stop_critical_timings(); /* don't trace print latency */ |
1da177e4 | 1127 | call_console_drivers(_con_start, _log_end); |
81d68a96 | 1128 | start_critical_timings(); |
1da177e4 LT |
1129 | local_irq_restore(flags); |
1130 | } | |
1131 | console_locked = 0; | |
1da177e4 LT |
1132 | up(&console_sem); |
1133 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
1134 | if (wake_klogd) |
1135 | wake_up_klogd(); | |
1da177e4 LT |
1136 | } |
1137 | EXPORT_SYMBOL(release_console_sem); | |
1138 | ||
ddad86c2 MW |
1139 | /** |
1140 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1141 | * |
1142 | * If the console code is currently allowed to sleep, and | |
1143 | * if this CPU should yield the CPU to another task, do | |
1144 | * so here. | |
1145 | * | |
1146 | * Must be called within acquire_console_sem(). | |
1147 | */ | |
1148 | void __sched console_conditional_schedule(void) | |
1149 | { | |
1150 | if (console_may_schedule) | |
1151 | cond_resched(); | |
1152 | } | |
1153 | EXPORT_SYMBOL(console_conditional_schedule); | |
1154 | ||
1da177e4 LT |
1155 | void console_unblank(void) |
1156 | { | |
1157 | struct console *c; | |
1158 | ||
1159 | /* | |
1160 | * console_unblank can no longer be called in interrupt context unless | |
1161 | * oops_in_progress is set to 1.. | |
1162 | */ | |
1163 | if (oops_in_progress) { | |
1164 | if (down_trylock(&console_sem) != 0) | |
1165 | return; | |
1166 | } else | |
1167 | acquire_console_sem(); | |
1168 | ||
1169 | console_locked = 1; | |
1170 | console_may_schedule = 0; | |
4d091611 | 1171 | for_each_console(c) |
1da177e4 LT |
1172 | if ((c->flags & CON_ENABLED) && c->unblank) |
1173 | c->unblank(); | |
1174 | release_console_sem(); | |
1175 | } | |
1da177e4 LT |
1176 | |
1177 | /* | |
1178 | * Return the console tty driver structure and its associated index | |
1179 | */ | |
1180 | struct tty_driver *console_device(int *index) | |
1181 | { | |
1182 | struct console *c; | |
1183 | struct tty_driver *driver = NULL; | |
1184 | ||
1185 | acquire_console_sem(); | |
4d091611 | 1186 | for_each_console(c) { |
1da177e4 LT |
1187 | if (!c->device) |
1188 | continue; | |
1189 | driver = c->device(c, index); | |
1190 | if (driver) | |
1191 | break; | |
1192 | } | |
1193 | release_console_sem(); | |
1194 | return driver; | |
1195 | } | |
1196 | ||
1197 | /* | |
1198 | * Prevent further output on the passed console device so that (for example) | |
1199 | * serial drivers can disable console output before suspending a port, and can | |
1200 | * re-enable output afterwards. | |
1201 | */ | |
1202 | void console_stop(struct console *console) | |
1203 | { | |
1204 | acquire_console_sem(); | |
1205 | console->flags &= ~CON_ENABLED; | |
1206 | release_console_sem(); | |
1207 | } | |
1208 | EXPORT_SYMBOL(console_stop); | |
1209 | ||
1210 | void console_start(struct console *console) | |
1211 | { | |
1212 | acquire_console_sem(); | |
1213 | console->flags |= CON_ENABLED; | |
1214 | release_console_sem(); | |
1215 | } | |
1216 | EXPORT_SYMBOL(console_start); | |
1217 | ||
1218 | /* | |
1219 | * The console driver calls this routine during kernel initialization | |
1220 | * to register the console printing procedure with printk() and to | |
1221 | * print any messages that were printed by the kernel before the | |
1222 | * console driver was initialized. | |
4d091611 RG |
1223 | * |
1224 | * This can happen pretty early during the boot process (because of | |
1225 | * early_printk) - sometimes before setup_arch() completes - be careful | |
1226 | * of what kernel features are used - they may not be initialised yet. | |
1227 | * | |
1228 | * There are two types of consoles - bootconsoles (early_printk) and | |
1229 | * "real" consoles (everything which is not a bootconsole) which are | |
1230 | * handled differently. | |
1231 | * - Any number of bootconsoles can be registered at any time. | |
1232 | * - As soon as a "real" console is registered, all bootconsoles | |
1233 | * will be unregistered automatically. | |
1234 | * - Once a "real" console is registered, any attempt to register a | |
1235 | * bootconsoles will be rejected | |
1da177e4 | 1236 | */ |
4d091611 | 1237 | void register_console(struct console *newcon) |
1da177e4 | 1238 | { |
40dc5651 | 1239 | int i; |
1da177e4 | 1240 | unsigned long flags; |
4d091611 | 1241 | struct console *bcon = NULL; |
1da177e4 | 1242 | |
4d091611 RG |
1243 | /* |
1244 | * before we register a new CON_BOOT console, make sure we don't | |
1245 | * already have a valid console | |
1246 | */ | |
1247 | if (console_drivers && newcon->flags & CON_BOOT) { | |
1248 | /* find the last or real console */ | |
1249 | for_each_console(bcon) { | |
1250 | if (!(bcon->flags & CON_BOOT)) { | |
1251 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", | |
1252 | newcon->name, newcon->index); | |
1253 | return; | |
1254 | } | |
1255 | } | |
69331af7 GH |
1256 | } |
1257 | ||
4d091611 RG |
1258 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1259 | bcon = console_drivers; | |
1260 | ||
1261 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
1262 | preferred_console = selected_console; |
1263 | ||
4d091611 RG |
1264 | if (newcon->early_setup) |
1265 | newcon->early_setup(); | |
18a8bd94 | 1266 | |
1da177e4 LT |
1267 | /* |
1268 | * See if we want to use this console driver. If we | |
1269 | * didn't select a console we take the first one | |
1270 | * that registers here. | |
1271 | */ | |
1272 | if (preferred_console < 0) { | |
4d091611 RG |
1273 | if (newcon->index < 0) |
1274 | newcon->index = 0; | |
1275 | if (newcon->setup == NULL || | |
1276 | newcon->setup(newcon, NULL) == 0) { | |
1277 | newcon->flags |= CON_ENABLED; | |
1278 | if (newcon->device) { | |
1279 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
1280 | preferred_console = 0; |
1281 | } | |
1da177e4 LT |
1282 | } |
1283 | } | |
1284 | ||
1285 | /* | |
1286 | * See if this console matches one we selected on | |
1287 | * the command line. | |
1288 | */ | |
40dc5651 JJ |
1289 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1290 | i++) { | |
4d091611 | 1291 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1da177e4 | 1292 | continue; |
4d091611 RG |
1293 | if (newcon->index >= 0 && |
1294 | newcon->index != console_cmdline[i].index) | |
1da177e4 | 1295 | continue; |
4d091611 RG |
1296 | if (newcon->index < 0) |
1297 | newcon->index = console_cmdline[i].index; | |
f7511d5f ST |
1298 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1299 | if (console_cmdline[i].brl_options) { | |
4d091611 RG |
1300 | newcon->flags |= CON_BRL; |
1301 | braille_register_console(newcon, | |
f7511d5f ST |
1302 | console_cmdline[i].index, |
1303 | console_cmdline[i].options, | |
1304 | console_cmdline[i].brl_options); | |
1305 | return; | |
1306 | } | |
1307 | #endif | |
4d091611 RG |
1308 | if (newcon->setup && |
1309 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 1310 | break; |
4d091611 RG |
1311 | newcon->flags |= CON_ENABLED; |
1312 | newcon->index = console_cmdline[i].index; | |
ab4af03a | 1313 | if (i == selected_console) { |
4d091611 | 1314 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
1315 | preferred_console = selected_console; |
1316 | } | |
1da177e4 LT |
1317 | break; |
1318 | } | |
1319 | ||
4d091611 | 1320 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
1321 | return; |
1322 | ||
8259cf43 RG |
1323 | /* |
1324 | * If we have a bootconsole, and are switching to a real console, | |
1325 | * don't print everything out again, since when the boot console, and | |
1326 | * the real console are the same physical device, it's annoying to | |
1327 | * see the beginning boot messages twice | |
1328 | */ | |
1329 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 1330 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
1331 | |
1332 | /* | |
1333 | * Put this console in the list - keep the | |
1334 | * preferred driver at the head of the list. | |
1335 | */ | |
1336 | acquire_console_sem(); | |
4d091611 RG |
1337 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1338 | newcon->next = console_drivers; | |
1339 | console_drivers = newcon; | |
1340 | if (newcon->next) | |
1341 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 1342 | } else { |
4d091611 RG |
1343 | newcon->next = console_drivers->next; |
1344 | console_drivers->next = newcon; | |
1da177e4 | 1345 | } |
4d091611 | 1346 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 LT |
1347 | /* |
1348 | * release_console_sem() will print out the buffered messages | |
1349 | * for us. | |
1350 | */ | |
1351 | spin_lock_irqsave(&logbuf_lock, flags); | |
1352 | con_start = log_start; | |
1353 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1354 | } | |
1355 | release_console_sem(); | |
fbc92a34 | 1356 | console_sysfs_notify(); |
8259cf43 RG |
1357 | |
1358 | /* | |
1359 | * By unregistering the bootconsoles after we enable the real console | |
1360 | * we get the "console xxx enabled" message on all the consoles - | |
1361 | * boot consoles, real consoles, etc - this is to ensure that end | |
1362 | * users know there might be something in the kernel's log buffer that | |
1363 | * went to the bootconsole (that they do not see on the real console) | |
1364 | */ | |
1365 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) { | |
1366 | /* we need to iterate through twice, to make sure we print | |
1367 | * everything out, before we unregister the console(s) | |
1368 | */ | |
1369 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", | |
1370 | newcon->name, newcon->index); | |
1371 | for_each_console(bcon) | |
1372 | if (bcon->flags & CON_BOOT) | |
1373 | unregister_console(bcon); | |
1374 | } else { | |
1375 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", | |
1376 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
1377 | newcon->name, newcon->index); | |
1378 | } | |
1da177e4 LT |
1379 | } |
1380 | EXPORT_SYMBOL(register_console); | |
1381 | ||
40dc5651 | 1382 | int unregister_console(struct console *console) |
1da177e4 | 1383 | { |
40dc5651 | 1384 | struct console *a, *b; |
1da177e4 LT |
1385 | int res = 1; |
1386 | ||
f7511d5f ST |
1387 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1388 | if (console->flags & CON_BRL) | |
1389 | return braille_unregister_console(console); | |
1390 | #endif | |
1391 | ||
1da177e4 LT |
1392 | acquire_console_sem(); |
1393 | if (console_drivers == console) { | |
1394 | console_drivers=console->next; | |
1395 | res = 0; | |
e9b15b54 | 1396 | } else if (console_drivers) { |
1da177e4 LT |
1397 | for (a=console_drivers->next, b=console_drivers ; |
1398 | a; b=a, a=b->next) { | |
1399 | if (a == console) { | |
1400 | b->next = a->next; | |
1401 | res = 0; | |
1402 | break; | |
40dc5651 | 1403 | } |
1da177e4 LT |
1404 | } |
1405 | } | |
40dc5651 | 1406 | |
69331af7 | 1407 | /* |
ab4af03a GE |
1408 | * If this isn't the last console and it has CON_CONSDEV set, we |
1409 | * need to set it on the next preferred console. | |
1da177e4 | 1410 | */ |
69331af7 | 1411 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1412 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 LT |
1413 | |
1414 | release_console_sem(); | |
fbc92a34 | 1415 | console_sysfs_notify(); |
1da177e4 LT |
1416 | return res; |
1417 | } | |
1418 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1419 | |
034260d6 | 1420 | static int __init printk_late_init(void) |
0c5564bd | 1421 | { |
4d091611 RG |
1422 | struct console *con; |
1423 | ||
1424 | for_each_console(con) { | |
1425 | if (con->flags & CON_BOOT) { | |
cb00e99c | 1426 | printk(KERN_INFO "turn off boot console %s%d\n", |
4d091611 | 1427 | con->name, con->index); |
42c2c8c8 | 1428 | unregister_console(con); |
cb00e99c | 1429 | } |
0c5564bd | 1430 | } |
034260d6 | 1431 | hotcpu_notifier(console_cpu_notify, 0); |
0c5564bd RG |
1432 | return 0; |
1433 | } | |
034260d6 | 1434 | late_initcall(printk_late_init); |
0c5564bd | 1435 | |
7ef3d2fd | 1436 | #if defined CONFIG_PRINTK |
717115e1 | 1437 | |
1da177e4 LT |
1438 | /* |
1439 | * printk rate limiting, lifted from the networking subsystem. | |
1440 | * | |
641de9d8 UKK |
1441 | * This enforces a rate limit: not more than 10 kernel messages |
1442 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 1443 | */ |
641de9d8 UKK |
1444 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1445 | ||
5c828713 | 1446 | int __printk_ratelimit(const char *func) |
1da177e4 | 1447 | { |
5c828713 | 1448 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 1449 | } |
5c828713 | 1450 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
1451 | |
1452 | /** | |
1453 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1454 | * @caller_jiffies: pointer to caller's state | |
1455 | * @interval_msecs: minimum interval between prints | |
1456 | * | |
1457 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1458 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1459 | * returned true. | |
1460 | */ | |
1461 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1462 | unsigned int interval_msecs) | |
1463 | { | |
f2d28a2e GK |
1464 | if (*caller_jiffies == 0 |
1465 | || !time_in_range(jiffies, *caller_jiffies, | |
1466 | *caller_jiffies | |
1467 | + msecs_to_jiffies(interval_msecs))) { | |
1468 | *caller_jiffies = jiffies; | |
f46c4833 AM |
1469 | return true; |
1470 | } | |
1471 | return false; | |
1472 | } | |
1473 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
1474 | |
1475 | static DEFINE_SPINLOCK(dump_list_lock); | |
1476 | static LIST_HEAD(dump_list); | |
1477 | ||
1478 | /** | |
1479 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 1480 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1481 | * |
1482 | * Adds a kernel log dumper to the system. The dump callback in the | |
1483 | * structure will be called when the kernel oopses or panics and must be | |
1484 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
1485 | */ | |
1486 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
1487 | { | |
1488 | unsigned long flags; | |
1489 | int err = -EBUSY; | |
1490 | ||
1491 | /* The dump callback needs to be set */ | |
1492 | if (!dumper->dump) | |
1493 | return -EINVAL; | |
1494 | ||
1495 | spin_lock_irqsave(&dump_list_lock, flags); | |
1496 | /* Don't allow registering multiple times */ | |
1497 | if (!dumper->registered) { | |
1498 | dumper->registered = 1; | |
1499 | list_add_tail(&dumper->list, &dump_list); | |
1500 | err = 0; | |
1501 | } | |
1502 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1503 | ||
1504 | return err; | |
1505 | } | |
1506 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
1507 | ||
1508 | /** | |
1509 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 1510 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1511 | * |
1512 | * Removes a dump device from the system. Returns zero on success and | |
1513 | * %-EINVAL otherwise. | |
1514 | */ | |
1515 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
1516 | { | |
1517 | unsigned long flags; | |
1518 | int err = -EINVAL; | |
1519 | ||
1520 | spin_lock_irqsave(&dump_list_lock, flags); | |
1521 | if (dumper->registered) { | |
1522 | dumper->registered = 0; | |
1523 | list_del(&dumper->list); | |
1524 | err = 0; | |
1525 | } | |
1526 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1527 | ||
1528 | return err; | |
1529 | } | |
1530 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
1531 | ||
6c095efd | 1532 | static const char * const kmsg_reasons[] = { |
456b565c SK |
1533 | [KMSG_DUMP_OOPS] = "oops", |
1534 | [KMSG_DUMP_PANIC] = "panic", | |
0f4bd46e | 1535 | [KMSG_DUMP_KEXEC] = "kexec", |
456b565c SK |
1536 | }; |
1537 | ||
1538 | static const char *kmsg_to_str(enum kmsg_dump_reason reason) | |
1539 | { | |
1540 | if (reason >= ARRAY_SIZE(kmsg_reasons) || reason < 0) | |
1541 | return "unknown"; | |
1542 | ||
1543 | return kmsg_reasons[reason]; | |
1544 | } | |
1545 | ||
1546 | /** | |
1547 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
1548 | * @reason: the reason (oops, panic etc) for dumping | |
1549 | * | |
1550 | * Iterate through each of the dump devices and call the oops/panic | |
1551 | * callbacks with the log buffer. | |
1552 | */ | |
1553 | void kmsg_dump(enum kmsg_dump_reason reason) | |
1554 | { | |
1555 | unsigned long end; | |
1556 | unsigned chars; | |
1557 | struct kmsg_dumper *dumper; | |
1558 | const char *s1, *s2; | |
1559 | unsigned long l1, l2; | |
1560 | unsigned long flags; | |
1561 | ||
1562 | /* Theoretically, the log could move on after we do this, but | |
1563 | there's not a lot we can do about that. The new messages | |
1564 | will overwrite the start of what we dump. */ | |
1565 | spin_lock_irqsave(&logbuf_lock, flags); | |
1566 | end = log_end & LOG_BUF_MASK; | |
1567 | chars = logged_chars; | |
1568 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1569 | ||
8c4af38e AK |
1570 | if (chars > end) { |
1571 | s1 = log_buf + log_buf_len - chars + end; | |
1572 | l1 = chars - end; | |
456b565c SK |
1573 | |
1574 | s2 = log_buf; | |
1575 | l2 = end; | |
1576 | } else { | |
1577 | s1 = ""; | |
1578 | l1 = 0; | |
1579 | ||
8c4af38e AK |
1580 | s2 = log_buf + end - chars; |
1581 | l2 = chars; | |
456b565c SK |
1582 | } |
1583 | ||
1584 | if (!spin_trylock_irqsave(&dump_list_lock, flags)) { | |
1585 | printk(KERN_ERR "dump_kmsg: dump list lock is held during %s, skipping dump\n", | |
1586 | kmsg_to_str(reason)); | |
1587 | return; | |
1588 | } | |
1589 | list_for_each_entry(dumper, &dump_list, list) | |
1590 | dumper->dump(dumper, reason, s1, l1, s2, l2); | |
1591 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1592 | } | |
7ef3d2fd | 1593 | #endif |