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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/kernel/printk.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * Modified to make sys_syslog() more flexible: added commands to | |
7 | * return the last 4k of kernel messages, regardless of whether | |
8 | * they've been read or not. Added option to suppress kernel printk's | |
9 | * to the console. Added hook for sending the console messages | |
10 | * elsewhere, in preparation for a serial line console (someday). | |
11 | * Ted Ts'o, 2/11/93. | |
12 | * Modified for sysctl support, 1/8/97, Chris Horn. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 | 15 | * Rewrote bits to get rid of console_lock |
e1f8e874 | 16 | * 01Mar01 Andrew Morton |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
1da177e4 LT |
23 | #include <linux/console.h> |
24 | #include <linux/init.h> | |
bfe8df3d RD |
25 | #include <linux/jiffies.h> |
26 | #include <linux/nmi.h> | |
1da177e4 | 27 | #include <linux/module.h> |
3b9c0410 | 28 | #include <linux/moduleparam.h> |
1da177e4 | 29 | #include <linux/interrupt.h> /* For in_interrupt() */ |
1da177e4 LT |
30 | #include <linux/delay.h> |
31 | #include <linux/smp.h> | |
32 | #include <linux/security.h> | |
33 | #include <linux/bootmem.h> | |
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 | ||
076f9776 IM |
47 | /* |
48 | * Architectures can override it: | |
49 | */ | |
e17ba73b | 50 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
076f9776 IM |
51 | { |
52 | } | |
53 | ||
1da177e4 LT |
54 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
55 | ||
56 | /* printk's without a loglevel use this.. */ | |
5af5bcb8 | 57 | #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL |
1da177e4 LT |
58 | |
59 | /* We show everything that is MORE important than this.. */ | |
60 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
61 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
62 | ||
63 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
64 | ||
65 | int console_printk[4] = { | |
66 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
67 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
68 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
69 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
70 | }; | |
71 | ||
1da177e4 | 72 | /* |
0bbfb7c2 | 73 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
74 | * their unblank() callback or not. So let's export it. |
75 | */ | |
76 | int oops_in_progress; | |
77 | EXPORT_SYMBOL(oops_in_progress); | |
78 | ||
79 | /* | |
80 | * console_sem protects the console_drivers list, and also | |
81 | * provides serialisation for access to the entire console | |
82 | * driver system. | |
83 | */ | |
5b8c4f23 | 84 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 85 | struct console *console_drivers; |
a29d1cfe IM |
86 | EXPORT_SYMBOL_GPL(console_drivers); |
87 | ||
1da177e4 LT |
88 | /* |
89 | * This is used for debugging the mess that is the VT code by | |
90 | * keeping track if we have the console semaphore held. It's | |
91 | * definitely not the perfect debug tool (we don't know if _WE_ | |
92 | * hold it are racing, but it helps tracking those weird code | |
93 | * path in the console code where we end up in places I want | |
94 | * locked without the console sempahore held | |
95 | */ | |
557240b4 | 96 | static int console_locked, console_suspended; |
1da177e4 LT |
97 | |
98 | /* | |
99 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
100 | * It is also used in interesting ways to provide interlocking in | |
ac751efa | 101 | * console_unlock();. |
1da177e4 LT |
102 | */ |
103 | static DEFINE_SPINLOCK(logbuf_lock); | |
104 | ||
eed4a2ab | 105 | #define LOG_BUF_MASK (log_buf_len-1) |
1da177e4 LT |
106 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
107 | ||
108 | /* | |
109 | * The indices into log_buf are not constrained to log_buf_len - they | |
110 | * must be masked before subscripting | |
111 | */ | |
eed4a2ab DV |
112 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
113 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ | |
114 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 | 115 | |
fe3d8ad3 FT |
116 | /* |
117 | * If exclusive_console is non-NULL then only this console is to be printed to. | |
118 | */ | |
119 | static struct console *exclusive_console; | |
120 | ||
1da177e4 LT |
121 | /* |
122 | * Array of consoles built from command line options (console=) | |
123 | */ | |
124 | struct console_cmdline | |
125 | { | |
126 | char name[8]; /* Name of the driver */ | |
127 | int index; /* Minor dev. to use */ | |
128 | char *options; /* Options for the driver */ | |
f7511d5f ST |
129 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
130 | char *brl_options; /* Options for braille driver */ | |
131 | #endif | |
1da177e4 LT |
132 | }; |
133 | ||
134 | #define MAX_CMDLINECONSOLES 8 | |
135 | ||
136 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
137 | static int selected_console = -1; | |
138 | static int preferred_console = -1; | |
9e124fe1 MA |
139 | int console_set_on_cmdline; |
140 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
141 | |
142 | /* Flag: console code may call schedule() */ | |
143 | static int console_may_schedule; | |
144 | ||
d59745ce MM |
145 | #ifdef CONFIG_PRINTK |
146 | ||
147 | static char __log_buf[__LOG_BUF_LEN]; | |
148 | static char *log_buf = __log_buf; | |
149 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 150 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
cea83886 | 151 | static int saved_console_loglevel = -1; |
d59745ce | 152 | |
04d491ab NH |
153 | #ifdef CONFIG_KEXEC |
154 | /* | |
155 | * This appends the listed symbols to /proc/vmcoreinfo | |
156 | * | |
157 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
158 | * obtain access to symbols that are otherwise very difficult to locate. These | |
159 | * symbols are specifically used so that utilities can access and extract the | |
160 | * dmesg log from a vmcore file after a crash. | |
161 | */ | |
162 | void log_buf_kexec_setup(void) | |
163 | { | |
164 | VMCOREINFO_SYMBOL(log_buf); | |
165 | VMCOREINFO_SYMBOL(log_end); | |
166 | VMCOREINFO_SYMBOL(log_buf_len); | |
167 | VMCOREINFO_SYMBOL(logged_chars); | |
168 | } | |
169 | #endif | |
170 | ||
162a7e75 MT |
171 | /* requested log_buf_len from kernel cmdline */ |
172 | static unsigned long __initdata new_log_buf_len; | |
173 | ||
174 | /* save requested log_buf_len since it's too early to process it */ | |
1da177e4 LT |
175 | static int __init log_buf_len_setup(char *str) |
176 | { | |
eed4a2ab | 177 | unsigned size = memparse(str, &str); |
1da177e4 LT |
178 | |
179 | if (size) | |
180 | size = roundup_pow_of_two(size); | |
162a7e75 MT |
181 | if (size > log_buf_len) |
182 | new_log_buf_len = size; | |
183 | ||
184 | return 0; | |
1da177e4 | 185 | } |
162a7e75 MT |
186 | early_param("log_buf_len", log_buf_len_setup); |
187 | ||
188 | void __init setup_log_buf(int early) | |
189 | { | |
190 | unsigned long flags; | |
191 | unsigned start, dest_idx, offset; | |
192 | char *new_log_buf; | |
193 | int free; | |
194 | ||
195 | if (!new_log_buf_len) | |
196 | return; | |
1da177e4 | 197 | |
162a7e75 MT |
198 | if (early) { |
199 | unsigned long mem; | |
200 | ||
201 | mem = memblock_alloc(new_log_buf_len, PAGE_SIZE); | |
202 | if (mem == MEMBLOCK_ERROR) | |
203 | return; | |
204 | new_log_buf = __va(mem); | |
205 | } else { | |
206 | new_log_buf = alloc_bootmem_nopanic(new_log_buf_len); | |
207 | } | |
208 | ||
209 | if (unlikely(!new_log_buf)) { | |
210 | pr_err("log_buf_len: %ld bytes not available\n", | |
211 | new_log_buf_len); | |
212 | return; | |
213 | } | |
214 | ||
215 | spin_lock_irqsave(&logbuf_lock, flags); | |
216 | log_buf_len = new_log_buf_len; | |
217 | log_buf = new_log_buf; | |
218 | new_log_buf_len = 0; | |
219 | free = __LOG_BUF_LEN - log_end; | |
220 | ||
221 | offset = start = min(con_start, log_start); | |
222 | dest_idx = 0; | |
223 | while (start != log_end) { | |
224 | unsigned log_idx_mask = start & (__LOG_BUF_LEN - 1); | |
225 | ||
226 | log_buf[dest_idx] = __log_buf[log_idx_mask]; | |
227 | start++; | |
228 | dest_idx++; | |
229 | } | |
230 | log_start -= offset; | |
231 | con_start -= offset; | |
232 | log_end -= offset; | |
233 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
234 | ||
235 | pr_info("log_buf_len: %d\n", log_buf_len); | |
236 | pr_info("early log buf free: %d(%d%%)\n", | |
237 | free, (free * 100) / __LOG_BUF_LEN); | |
238 | } | |
1da177e4 | 239 | |
bfe8df3d RD |
240 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
241 | ||
674dff65 | 242 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 243 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
244 | |
245 | static int __init boot_delay_setup(char *str) | |
246 | { | |
247 | unsigned long lpj; | |
bfe8df3d RD |
248 | |
249 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
250 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
251 | ||
252 | get_option(&str, &boot_delay); | |
253 | if (boot_delay > 10 * 1000) | |
254 | boot_delay = 0; | |
255 | ||
3a3b6ed2 DY |
256 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
257 | "HZ: %d, loops_per_msec: %llu\n", | |
258 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
bfe8df3d RD |
259 | return 1; |
260 | } | |
261 | __setup("boot_delay=", boot_delay_setup); | |
262 | ||
263 | static void boot_delay_msec(void) | |
264 | { | |
265 | unsigned long long k; | |
266 | unsigned long timeout; | |
267 | ||
268 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
269 | return; | |
270 | ||
3a3b6ed2 | 271 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
272 | |
273 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
274 | while (k) { | |
275 | k--; | |
276 | cpu_relax(); | |
277 | /* | |
278 | * use (volatile) jiffies to prevent | |
279 | * compiler reduction; loop termination via jiffies | |
280 | * is secondary and may or may not happen. | |
281 | */ | |
282 | if (time_after(jiffies, timeout)) | |
283 | break; | |
284 | touch_nmi_watchdog(); | |
285 | } | |
286 | } | |
287 | #else | |
288 | static inline void boot_delay_msec(void) | |
289 | { | |
290 | } | |
291 | #endif | |
292 | ||
eaf06b24 DR |
293 | #ifdef CONFIG_SECURITY_DMESG_RESTRICT |
294 | int dmesg_restrict = 1; | |
295 | #else | |
296 | int dmesg_restrict; | |
297 | #endif | |
298 | ||
ee24aebf LT |
299 | static int syslog_action_restricted(int type) |
300 | { | |
301 | if (dmesg_restrict) | |
302 | return 1; | |
303 | /* Unless restricted, we allow "read all" and "get buffer size" for everybody */ | |
304 | return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; | |
305 | } | |
306 | ||
307 | static int check_syslog_permissions(int type, bool from_file) | |
308 | { | |
309 | /* | |
310 | * If this is from /proc/kmsg and we've already opened it, then we've | |
311 | * already done the capabilities checks at open time. | |
312 | */ | |
313 | if (from_file && type != SYSLOG_ACTION_OPEN) | |
314 | return 0; | |
315 | ||
316 | if (syslog_action_restricted(type)) { | |
317 | if (capable(CAP_SYSLOG)) | |
318 | return 0; | |
319 | /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */ | |
320 | if (capable(CAP_SYS_ADMIN)) { | |
321 | WARN_ONCE(1, "Attempt to access syslog with CAP_SYS_ADMIN " | |
322 | "but no CAP_SYSLOG (deprecated).\n"); | |
323 | return 0; | |
324 | } | |
325 | return -EPERM; | |
326 | } | |
327 | return 0; | |
328 | } | |
329 | ||
00234592 | 330 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
1da177e4 | 331 | { |
eed4a2ab | 332 | unsigned i, j, limit, count; |
1da177e4 LT |
333 | int do_clear = 0; |
334 | char c; | |
ee24aebf | 335 | int error; |
1da177e4 | 336 | |
ee24aebf LT |
337 | error = check_syslog_permissions(type, from_file); |
338 | if (error) | |
339 | goto out; | |
12b3052c EP |
340 | |
341 | error = security_syslog(type); | |
1da177e4 LT |
342 | if (error) |
343 | return error; | |
344 | ||
345 | switch (type) { | |
d78ca3cd | 346 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 347 | break; |
d78ca3cd | 348 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 349 | break; |
d78ca3cd | 350 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 LT |
351 | error = -EINVAL; |
352 | if (!buf || len < 0) | |
353 | goto out; | |
354 | error = 0; | |
355 | if (!len) | |
356 | goto out; | |
357 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
358 | error = -EFAULT; | |
359 | goto out; | |
360 | } | |
40dc5651 JJ |
361 | error = wait_event_interruptible(log_wait, |
362 | (log_start - log_end)); | |
1da177e4 LT |
363 | if (error) |
364 | goto out; | |
365 | i = 0; | |
366 | spin_lock_irq(&logbuf_lock); | |
367 | while (!error && (log_start != log_end) && i < len) { | |
368 | c = LOG_BUF(log_start); | |
369 | log_start++; | |
370 | spin_unlock_irq(&logbuf_lock); | |
371 | error = __put_user(c,buf); | |
372 | buf++; | |
373 | i++; | |
374 | cond_resched(); | |
375 | spin_lock_irq(&logbuf_lock); | |
376 | } | |
377 | spin_unlock_irq(&logbuf_lock); | |
378 | if (!error) | |
379 | error = i; | |
380 | break; | |
d78ca3cd KC |
381 | /* Read/clear last kernel messages */ |
382 | case SYSLOG_ACTION_READ_CLEAR: | |
40dc5651 | 383 | do_clear = 1; |
1da177e4 | 384 | /* FALL THRU */ |
d78ca3cd KC |
385 | /* Read last kernel messages */ |
386 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 LT |
387 | error = -EINVAL; |
388 | if (!buf || len < 0) | |
389 | goto out; | |
390 | error = 0; | |
391 | if (!len) | |
392 | goto out; | |
393 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
394 | error = -EFAULT; | |
395 | goto out; | |
396 | } | |
397 | count = len; | |
398 | if (count > log_buf_len) | |
399 | count = log_buf_len; | |
400 | spin_lock_irq(&logbuf_lock); | |
401 | if (count > logged_chars) | |
402 | count = logged_chars; | |
403 | if (do_clear) | |
404 | logged_chars = 0; | |
405 | limit = log_end; | |
406 | /* | |
407 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 408 | * printk() could overwrite the messages |
1da177e4 LT |
409 | * we try to copy to user space. Therefore |
410 | * the messages are copied in reverse. <manfreds> | |
411 | */ | |
40dc5651 | 412 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
413 | j = limit-1-i; |
414 | if (j + log_buf_len < log_end) | |
415 | break; | |
416 | c = LOG_BUF(j); | |
417 | spin_unlock_irq(&logbuf_lock); | |
418 | error = __put_user(c,&buf[count-1-i]); | |
419 | cond_resched(); | |
420 | spin_lock_irq(&logbuf_lock); | |
421 | } | |
422 | spin_unlock_irq(&logbuf_lock); | |
423 | if (error) | |
424 | break; | |
425 | error = i; | |
40dc5651 | 426 | if (i != count) { |
1da177e4 LT |
427 | int offset = count-error; |
428 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 429 | for (i = 0; i < error; i++) { |
1da177e4 LT |
430 | if (__get_user(c,&buf[i+offset]) || |
431 | __put_user(c,&buf[i])) { | |
432 | error = -EFAULT; | |
433 | break; | |
434 | } | |
435 | cond_resched(); | |
436 | } | |
437 | } | |
438 | break; | |
d78ca3cd KC |
439 | /* Clear ring buffer */ |
440 | case SYSLOG_ACTION_CLEAR: | |
1da177e4 LT |
441 | logged_chars = 0; |
442 | break; | |
d78ca3cd KC |
443 | /* Disable logging to console */ |
444 | case SYSLOG_ACTION_CONSOLE_OFF: | |
1aaad49e FP |
445 | if (saved_console_loglevel == -1) |
446 | saved_console_loglevel = console_loglevel; | |
1da177e4 LT |
447 | console_loglevel = minimum_console_loglevel; |
448 | break; | |
d78ca3cd KC |
449 | /* Enable logging to console */ |
450 | case SYSLOG_ACTION_CONSOLE_ON: | |
1aaad49e FP |
451 | if (saved_console_loglevel != -1) { |
452 | console_loglevel = saved_console_loglevel; | |
453 | saved_console_loglevel = -1; | |
454 | } | |
1da177e4 | 455 | break; |
d78ca3cd KC |
456 | /* Set level of messages printed to console */ |
457 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 LT |
458 | error = -EINVAL; |
459 | if (len < 1 || len > 8) | |
460 | goto out; | |
461 | if (len < minimum_console_loglevel) | |
462 | len = minimum_console_loglevel; | |
463 | console_loglevel = len; | |
1aaad49e FP |
464 | /* Implicitly re-enable logging to console */ |
465 | saved_console_loglevel = -1; | |
1da177e4 LT |
466 | error = 0; |
467 | break; | |
d78ca3cd KC |
468 | /* Number of chars in the log buffer */ |
469 | case SYSLOG_ACTION_SIZE_UNREAD: | |
1da177e4 LT |
470 | error = log_end - log_start; |
471 | break; | |
d78ca3cd KC |
472 | /* Size of the log buffer */ |
473 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
474 | error = log_buf_len; |
475 | break; | |
476 | default: | |
477 | error = -EINVAL; | |
478 | break; | |
479 | } | |
480 | out: | |
481 | return error; | |
482 | } | |
483 | ||
1e7bfb21 | 484 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 485 | { |
00234592 | 486 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
1da177e4 LT |
487 | } |
488 | ||
67fc4e0c JW |
489 | #ifdef CONFIG_KGDB_KDB |
490 | /* kdb dmesg command needs access to the syslog buffer. do_syslog() | |
491 | * uses locks so it cannot be used during debugging. Just tell kdb | |
492 | * where the start and end of the physical and logical logs are. This | |
493 | * is equivalent to do_syslog(3). | |
494 | */ | |
495 | void kdb_syslog_data(char *syslog_data[4]) | |
496 | { | |
497 | syslog_data[0] = log_buf; | |
498 | syslog_data[1] = log_buf + log_buf_len; | |
499 | syslog_data[2] = log_buf + log_end - | |
500 | (logged_chars < log_buf_len ? logged_chars : log_buf_len); | |
501 | syslog_data[3] = log_buf + log_end; | |
502 | } | |
503 | #endif /* CONFIG_KGDB_KDB */ | |
504 | ||
1da177e4 LT |
505 | /* |
506 | * Call the console drivers on a range of log_buf | |
507 | */ | |
eed4a2ab | 508 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
509 | { |
510 | struct console *con; | |
511 | ||
4d091611 | 512 | for_each_console(con) { |
fe3d8ad3 FT |
513 | if (exclusive_console && con != exclusive_console) |
514 | continue; | |
76a8ad29 ME |
515 | if ((con->flags & CON_ENABLED) && con->write && |
516 | (cpu_online(smp_processor_id()) || | |
517 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
518 | con->write(con, &LOG_BUF(start), end - start); |
519 | } | |
520 | } | |
521 | ||
79290822 IM |
522 | static int __read_mostly ignore_loglevel; |
523 | ||
99eea6a1 | 524 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
525 | { |
526 | ignore_loglevel = 1; | |
527 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
528 | ||
c4772d99 | 529 | return 0; |
79290822 IM |
530 | } |
531 | ||
c4772d99 | 532 | early_param("ignore_loglevel", ignore_loglevel_setup); |
79290822 | 533 | |
1da177e4 LT |
534 | /* |
535 | * Write out chars from start to end - 1 inclusive | |
536 | */ | |
eed4a2ab DV |
537 | static void _call_console_drivers(unsigned start, |
538 | unsigned end, int msg_log_level) | |
1da177e4 | 539 | { |
79290822 | 540 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
541 | console_drivers && start != end) { |
542 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
543 | /* wrapped write */ | |
544 | __call_console_drivers(start & LOG_BUF_MASK, | |
545 | log_buf_len); | |
546 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
547 | } else { | |
548 | __call_console_drivers(start, end); | |
549 | } | |
550 | } | |
551 | } | |
552 | ||
9d90c8d9 KS |
553 | /* |
554 | * Parse the syslog header <[0-9]*>. The decimal value represents 32bit, the | |
555 | * lower 3 bit are the log level, the rest are the log facility. In case | |
556 | * userspace passes usual userspace syslog messages to /dev/kmsg or | |
557 | * /dev/ttyprintk, the log prefix might contain the facility. Printk needs | |
558 | * to extract the correct log level for in-kernel processing, and not mangle | |
559 | * the original value. | |
560 | * | |
561 | * If a prefix is found, the length of the prefix is returned. If 'level' is | |
562 | * passed, it will be filled in with the log level without a possible facility | |
563 | * value. If 'special' is passed, the special printk prefix chars are accepted | |
564 | * and returned. If no valid header is found, 0 is returned and the passed | |
565 | * variables are not touched. | |
566 | */ | |
567 | static size_t log_prefix(const char *p, unsigned int *level, char *special) | |
568 | { | |
569 | unsigned int lev = 0; | |
570 | char sp = '\0'; | |
571 | size_t len; | |
572 | ||
573 | if (p[0] != '<' || !p[1]) | |
574 | return 0; | |
575 | if (p[2] == '>') { | |
576 | /* usual single digit level number or special char */ | |
577 | switch (p[1]) { | |
578 | case '0' ... '7': | |
579 | lev = p[1] - '0'; | |
580 | break; | |
581 | case 'c': /* KERN_CONT */ | |
582 | case 'd': /* KERN_DEFAULT */ | |
583 | sp = p[1]; | |
584 | break; | |
585 | default: | |
586 | return 0; | |
587 | } | |
588 | len = 3; | |
589 | } else { | |
590 | /* multi digit including the level and facility number */ | |
591 | char *endp = NULL; | |
592 | ||
593 | if (p[1] < '0' && p[1] > '9') | |
594 | return 0; | |
595 | ||
596 | lev = (simple_strtoul(&p[1], &endp, 10) & 7); | |
597 | if (endp == NULL || endp[0] != '>') | |
598 | return 0; | |
599 | len = (endp + 1) - p; | |
600 | } | |
601 | ||
602 | /* do not accept special char if not asked for */ | |
603 | if (sp && !special) | |
604 | return 0; | |
605 | ||
606 | if (special) { | |
607 | *special = sp; | |
608 | /* return special char, do not touch level */ | |
609 | if (sp) | |
610 | return len; | |
611 | } | |
612 | ||
613 | if (level) | |
614 | *level = lev; | |
615 | return len; | |
616 | } | |
617 | ||
1da177e4 LT |
618 | /* |
619 | * Call the console drivers, asking them to write out | |
620 | * log_buf[start] to log_buf[end - 1]. | |
ac751efa | 621 | * The console_lock must be held. |
1da177e4 | 622 | */ |
eed4a2ab | 623 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 624 | { |
eed4a2ab | 625 | unsigned cur_index, start_print; |
1da177e4 LT |
626 | static int msg_level = -1; |
627 | ||
eed4a2ab | 628 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
629 | |
630 | cur_index = start; | |
631 | start_print = start; | |
632 | while (cur_index != end) { | |
9d90c8d9 KS |
633 | if (msg_level < 0 && ((end - cur_index) > 2)) { |
634 | /* strip log prefix */ | |
635 | cur_index += log_prefix(&LOG_BUF(cur_index), &msg_level, NULL); | |
1da177e4 LT |
636 | start_print = cur_index; |
637 | } | |
638 | while (cur_index != end) { | |
639 | char c = LOG_BUF(cur_index); | |
1da177e4 | 640 | |
40dc5651 | 641 | cur_index++; |
1da177e4 LT |
642 | if (c == '\n') { |
643 | if (msg_level < 0) { | |
644 | /* | |
645 | * printk() has already given us loglevel tags in | |
646 | * the buffer. This code is here in case the | |
647 | * log buffer has wrapped right round and scribbled | |
648 | * on those tags | |
649 | */ | |
650 | msg_level = default_message_loglevel; | |
651 | } | |
652 | _call_console_drivers(start_print, cur_index, msg_level); | |
653 | msg_level = -1; | |
654 | start_print = cur_index; | |
655 | break; | |
656 | } | |
657 | } | |
658 | } | |
659 | _call_console_drivers(start_print, end, msg_level); | |
660 | } | |
661 | ||
662 | static void emit_log_char(char c) | |
663 | { | |
664 | LOG_BUF(log_end) = c; | |
665 | log_end++; | |
666 | if (log_end - log_start > log_buf_len) | |
667 | log_start = log_end - log_buf_len; | |
668 | if (log_end - con_start > log_buf_len) | |
669 | con_start = log_end - log_buf_len; | |
670 | if (logged_chars < log_buf_len) | |
671 | logged_chars++; | |
672 | } | |
673 | ||
674 | /* | |
675 | * Zap console related locks when oopsing. Only zap at most once | |
676 | * every 10 seconds, to leave time for slow consoles to print a | |
677 | * full oops. | |
678 | */ | |
679 | static void zap_locks(void) | |
680 | { | |
681 | static unsigned long oops_timestamp; | |
682 | ||
683 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 684 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
685 | return; |
686 | ||
687 | oops_timestamp = jiffies; | |
688 | ||
689 | /* If a crash is occurring, make sure we can't deadlock */ | |
690 | spin_lock_init(&logbuf_lock); | |
691 | /* And make sure that we print immediately */ | |
5b8c4f23 | 692 | sema_init(&console_sem, 1); |
1da177e4 LT |
693 | } |
694 | ||
695 | #if defined(CONFIG_PRINTK_TIME) | |
696 | static int printk_time = 1; | |
697 | #else | |
698 | static int printk_time = 0; | |
699 | #endif | |
e84845c4 | 700 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 701 | |
76a8ad29 ME |
702 | /* Check if we have any console registered that can be called early in boot. */ |
703 | static int have_callable_console(void) | |
704 | { | |
705 | struct console *con; | |
706 | ||
4d091611 | 707 | for_each_console(con) |
76a8ad29 ME |
708 | if (con->flags & CON_ANYTIME) |
709 | return 1; | |
710 | ||
711 | return 0; | |
712 | } | |
713 | ||
ddad86c2 MW |
714 | /** |
715 | * printk - print a kernel message | |
716 | * @fmt: format string | |
717 | * | |
72fd4a35 | 718 | * This is printk(). It can be called from any context. We want it to work. |
40dc5651 | 719 | * |
ac751efa | 720 | * We try to grab the console_lock. If we succeed, it's easy - we log the output and |
1da177e4 LT |
721 | * call the console drivers. If we fail to get the semaphore we place the output |
722 | * into the log buffer and return. The current holder of the console_sem will | |
ac751efa TH |
723 | * notice the new output in console_unlock(); and will send it to the |
724 | * consoles before releasing the lock. | |
1da177e4 LT |
725 | * |
726 | * One effect of this deferred printing is that code which calls printk() and | |
727 | * then changes console_loglevel may break. This is because console_loglevel | |
728 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
729 | * |
730 | * See also: | |
731 | * printf(3) | |
20036fdc AK |
732 | * |
733 | * See the vsnprintf() documentation for format string extensions over C99. | |
1da177e4 | 734 | */ |
d59745ce | 735 | |
1da177e4 LT |
736 | asmlinkage int printk(const char *fmt, ...) |
737 | { | |
738 | va_list args; | |
739 | int r; | |
740 | ||
d37d39ae JW |
741 | #ifdef CONFIG_KGDB_KDB |
742 | if (unlikely(kdb_trap_printk)) { | |
743 | va_start(args, fmt); | |
744 | r = vkdb_printf(fmt, args); | |
745 | va_end(args); | |
746 | return r; | |
747 | } | |
748 | #endif | |
1da177e4 LT |
749 | va_start(args, fmt); |
750 | r = vprintk(fmt, args); | |
751 | va_end(args); | |
752 | ||
753 | return r; | |
754 | } | |
755 | ||
fe21773d DH |
756 | /* cpu currently holding logbuf_lock */ |
757 | static volatile unsigned int printk_cpu = UINT_MAX; | |
758 | ||
266c2e0a LT |
759 | /* |
760 | * Can we actually use the console at this time on this cpu? | |
761 | * | |
762 | * Console drivers may assume that per-cpu resources have | |
763 | * been allocated. So unless they're explicitly marked as | |
764 | * being able to cope (CON_ANYTIME) don't call them until | |
765 | * this CPU is officially up. | |
766 | */ | |
767 | static inline int can_use_console(unsigned int cpu) | |
768 | { | |
769 | return cpu_online(cpu) || have_callable_console(); | |
770 | } | |
771 | ||
772 | /* | |
773 | * Try to get console ownership to actually show the kernel | |
774 | * messages from a 'printk'. Return true (and with the | |
ac751efa | 775 | * console_lock held, and 'console_locked' set) if it |
266c2e0a LT |
776 | * is successful, false otherwise. |
777 | * | |
778 | * This gets called with the 'logbuf_lock' spinlock held and | |
779 | * interrupts disabled. It should return with 'lockbuf_lock' | |
780 | * released but interrupts still disabled. | |
781 | */ | |
ac751efa | 782 | static int console_trylock_for_printk(unsigned int cpu) |
8155c02a | 783 | __releases(&logbuf_lock) |
266c2e0a | 784 | { |
0b5e1c52 | 785 | int retval = 0, wake = 0; |
266c2e0a | 786 | |
ac751efa | 787 | if (console_trylock()) { |
093a07e2 LT |
788 | retval = 1; |
789 | ||
790 | /* | |
791 | * If we can't use the console, we need to release | |
792 | * the console semaphore by hand to avoid flushing | |
793 | * the buffer. We need to hold the console semaphore | |
794 | * in order to do this test safely. | |
795 | */ | |
796 | if (!can_use_console(cpu)) { | |
797 | console_locked = 0; | |
0b5e1c52 | 798 | wake = 1; |
093a07e2 LT |
799 | retval = 0; |
800 | } | |
801 | } | |
266c2e0a LT |
802 | printk_cpu = UINT_MAX; |
803 | spin_unlock(&logbuf_lock); | |
0b5e1c52 PZ |
804 | if (wake) |
805 | up(&console_sem); | |
266c2e0a LT |
806 | return retval; |
807 | } | |
3b8945e8 TH |
808 | static const char recursion_bug_msg [] = |
809 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
810 | static int recursion_bug; | |
edb123e1 | 811 | static int new_text_line = 1; |
3b8945e8 | 812 | static char printk_buf[1024]; |
32a76006 | 813 | |
af91322e DY |
814 | int printk_delay_msec __read_mostly; |
815 | ||
816 | static inline void printk_delay(void) | |
817 | { | |
818 | if (unlikely(printk_delay_msec)) { | |
819 | int m = printk_delay_msec; | |
820 | ||
821 | while (m--) { | |
822 | mdelay(1); | |
823 | touch_nmi_watchdog(); | |
824 | } | |
825 | } | |
826 | } | |
827 | ||
1da177e4 LT |
828 | asmlinkage int vprintk(const char *fmt, va_list args) |
829 | { | |
32a76006 | 830 | int printed_len = 0; |
09159308 | 831 | int current_log_level = default_message_loglevel; |
ac60ad74 | 832 | unsigned long flags; |
32a76006 | 833 | int this_cpu; |
1da177e4 | 834 | char *p; |
9d90c8d9 KS |
835 | size_t plen; |
836 | char special; | |
1da177e4 | 837 | |
bfe8df3d | 838 | boot_delay_msec(); |
af91322e | 839 | printk_delay(); |
bfe8df3d | 840 | |
fe21773d | 841 | preempt_disable(); |
1da177e4 | 842 | /* This stops the holder of console_sem just where we want him */ |
1efc5da3 | 843 | raw_local_irq_save(flags); |
32a76006 IM |
844 | this_cpu = smp_processor_id(); |
845 | ||
846 | /* | |
847 | * Ouch, printk recursed into itself! | |
848 | */ | |
849 | if (unlikely(printk_cpu == this_cpu)) { | |
850 | /* | |
851 | * If a crash is occurring during printk() on this CPU, | |
852 | * then try to get the crash message out but make sure | |
853 | * we can't deadlock. Otherwise just return to avoid the | |
854 | * recursion and return - but flag the recursion so that | |
855 | * it can be printed at the next appropriate moment: | |
856 | */ | |
857 | if (!oops_in_progress) { | |
3b8945e8 | 858 | recursion_bug = 1; |
32a76006 IM |
859 | goto out_restore_irqs; |
860 | } | |
861 | zap_locks(); | |
862 | } | |
863 | ||
a0f1ccfd IM |
864 | lockdep_off(); |
865 | spin_lock(&logbuf_lock); | |
32a76006 | 866 | printk_cpu = this_cpu; |
1da177e4 | 867 | |
3b8945e8 TH |
868 | if (recursion_bug) { |
869 | recursion_bug = 0; | |
870 | strcpy(printk_buf, recursion_bug_msg); | |
26cc271d | 871 | printed_len = strlen(recursion_bug_msg); |
32a76006 | 872 | } |
1da177e4 | 873 | /* Emit the output into the temporary buffer */ |
32a76006 | 874 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 875 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 876 | |
5fd29d6c LT |
877 | p = printk_buf; |
878 | ||
9d90c8d9 KS |
879 | /* Read log level and handle special printk prefix */ |
880 | plen = log_prefix(p, ¤t_log_level, &special); | |
881 | if (plen) { | |
882 | p += plen; | |
883 | ||
884 | switch (special) { | |
885 | case 'c': /* Strip <c> KERN_CONT, continue line */ | |
886 | plen = 0; | |
887 | break; | |
888 | case 'd': /* Strip <d> KERN_DEFAULT, start new line */ | |
889 | plen = 0; | |
890 | default: | |
891 | if (!new_text_line) { | |
892 | emit_log_char('\n'); | |
893 | new_text_line = 1; | |
5fd29d6c LT |
894 | } |
895 | } | |
896 | } | |
897 | ||
1da177e4 | 898 | /* |
9d90c8d9 KS |
899 | * Copy the output into log_buf. If the caller didn't provide |
900 | * the appropriate log prefix, we insert them here | |
1da177e4 | 901 | */ |
9d90c8d9 | 902 | for (; *p; p++) { |
ac60ad74 | 903 | if (new_text_line) { |
ac60ad74 NA |
904 | new_text_line = 0; |
905 | ||
9d90c8d9 KS |
906 | if (plen) { |
907 | /* Copy original log prefix */ | |
908 | int i; | |
909 | ||
910 | for (i = 0; i < plen; i++) | |
911 | emit_log_char(printk_buf[i]); | |
912 | printed_len += plen; | |
913 | } else { | |
914 | /* Add log prefix */ | |
915 | emit_log_char('<'); | |
916 | emit_log_char(current_log_level + '0'); | |
917 | emit_log_char('>'); | |
918 | printed_len += 3; | |
919 | } | |
920 | ||
1da177e4 | 921 | if (printk_time) { |
9d90c8d9 | 922 | /* Add the current time stamp */ |
1da177e4 LT |
923 | char tbuf[50], *tp; |
924 | unsigned tlen; | |
925 | unsigned long long t; | |
926 | unsigned long nanosec_rem; | |
927 | ||
326e96b9 | 928 | t = cpu_clock(printk_cpu); |
1da177e4 | 929 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
930 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
931 | (unsigned long) t, | |
932 | nanosec_rem / 1000); | |
1da177e4 LT |
933 | |
934 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
935 | emit_log_char(*tp); | |
025510cd | 936 | printed_len += tlen; |
1da177e4 | 937 | } |
ac60ad74 | 938 | |
1da177e4 LT |
939 | if (!*p) |
940 | break; | |
941 | } | |
ac60ad74 | 942 | |
1da177e4 LT |
943 | emit_log_char(*p); |
944 | if (*p == '\n') | |
ac60ad74 | 945 | new_text_line = 1; |
1da177e4 LT |
946 | } |
947 | ||
266c2e0a LT |
948 | /* |
949 | * Try to acquire and then immediately release the | |
950 | * console semaphore. The release will do all the | |
951 | * actual magic (print out buffers, wake up klogd, | |
952 | * etc). | |
953 | * | |
ac751efa | 954 | * The console_trylock_for_printk() function |
266c2e0a LT |
955 | * will release 'logbuf_lock' regardless of whether it |
956 | * actually gets the semaphore or not. | |
957 | */ | |
ac751efa TH |
958 | if (console_trylock_for_printk(this_cpu)) |
959 | console_unlock(); | |
76a8ad29 | 960 | |
266c2e0a | 961 | lockdep_on(); |
32a76006 | 962 | out_restore_irqs: |
266c2e0a | 963 | raw_local_irq_restore(flags); |
76a8ad29 | 964 | |
fe21773d | 965 | preempt_enable(); |
1da177e4 LT |
966 | return printed_len; |
967 | } | |
968 | EXPORT_SYMBOL(printk); | |
969 | EXPORT_SYMBOL(vprintk); | |
970 | ||
d59745ce MM |
971 | #else |
972 | ||
eed4a2ab | 973 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
974 | { |
975 | } | |
d59745ce MM |
976 | |
977 | #endif | |
978 | ||
f7511d5f ST |
979 | static int __add_preferred_console(char *name, int idx, char *options, |
980 | char *brl_options) | |
981 | { | |
982 | struct console_cmdline *c; | |
983 | int i; | |
984 | ||
985 | /* | |
986 | * See if this tty is not yet registered, and | |
987 | * if we have a slot free. | |
988 | */ | |
989 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
990 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
991 | console_cmdline[i].index == idx) { | |
992 | if (!brl_options) | |
993 | selected_console = i; | |
994 | return 0; | |
995 | } | |
996 | if (i == MAX_CMDLINECONSOLES) | |
997 | return -E2BIG; | |
998 | if (!brl_options) | |
999 | selected_console = i; | |
1000 | c = &console_cmdline[i]; | |
1001 | strlcpy(c->name, name, sizeof(c->name)); | |
1002 | c->options = options; | |
1003 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
1004 | c->brl_options = brl_options; | |
1005 | #endif | |
1006 | c->index = idx; | |
1007 | return 0; | |
1008 | } | |
2ea1c539 JB |
1009 | /* |
1010 | * Set up a list of consoles. Called from init/main.c | |
1011 | */ | |
1012 | static int __init console_setup(char *str) | |
1013 | { | |
eaa944af | 1014 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 1015 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
1016 | int idx; |
1017 | ||
f7511d5f ST |
1018 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1019 | if (!memcmp(str, "brl,", 4)) { | |
1020 | brl_options = ""; | |
1021 | str += 4; | |
1022 | } else if (!memcmp(str, "brl=", 4)) { | |
1023 | brl_options = str + 4; | |
1024 | str = strchr(brl_options, ','); | |
1025 | if (!str) { | |
1026 | printk(KERN_ERR "need port name after brl=\n"); | |
1027 | return 1; | |
1028 | } | |
1029 | *(str++) = 0; | |
1030 | } | |
1031 | #endif | |
1032 | ||
2ea1c539 JB |
1033 | /* |
1034 | * Decode str into name, index, options. | |
1035 | */ | |
1036 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
1037 | strcpy(buf, "ttyS"); |
1038 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 1039 | } else { |
eaa944af | 1040 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 1041 | } |
eaa944af | 1042 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
1043 | if ((options = strchr(str, ',')) != NULL) |
1044 | *(options++) = 0; | |
1045 | #ifdef __sparc__ | |
1046 | if (!strcmp(str, "ttya")) | |
eaa944af | 1047 | strcpy(buf, "ttyS0"); |
2ea1c539 | 1048 | if (!strcmp(str, "ttyb")) |
eaa944af | 1049 | strcpy(buf, "ttyS1"); |
2ea1c539 | 1050 | #endif |
eaa944af | 1051 | for (s = buf; *s; s++) |
2ea1c539 JB |
1052 | if ((*s >= '0' && *s <= '9') || *s == ',') |
1053 | break; | |
1054 | idx = simple_strtoul(s, NULL, 10); | |
1055 | *s = 0; | |
1056 | ||
f7511d5f | 1057 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 1058 | console_set_on_cmdline = 1; |
2ea1c539 JB |
1059 | return 1; |
1060 | } | |
1061 | __setup("console=", console_setup); | |
1062 | ||
3c0547ba MM |
1063 | /** |
1064 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
1065 | * @name: device name |
1066 | * @idx: device index | |
1067 | * @options: options for this console | |
3c0547ba MM |
1068 | * |
1069 | * The last preferred console added will be used for kernel messages | |
1070 | * and stdin/out/err for init. Normally this is used by console_setup | |
1071 | * above to handle user-supplied console arguments; however it can also | |
1072 | * be used by arch-specific code either to override the user or more | |
1073 | * commonly to provide a default console (ie from PROM variables) when | |
1074 | * the user has not supplied one. | |
1075 | */ | |
fb445ee5 | 1076 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 1077 | { |
f7511d5f | 1078 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
1079 | } |
1080 | ||
b6b1d877 | 1081 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
1082 | { |
1083 | struct console_cmdline *c; | |
1084 | int i; | |
1085 | ||
1086 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
1087 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
1088 | console_cmdline[i].index == idx) { | |
1089 | c = &console_cmdline[i]; | |
f735295b | 1090 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
1091 | c->name[sizeof(c->name) - 1] = 0; |
1092 | c->options = options; | |
1093 | c->index = idx_new; | |
1094 | return i; | |
1095 | } | |
1096 | /* not found */ | |
1097 | return -1; | |
1098 | } | |
1099 | ||
8f4ce8c3 AS |
1100 | int console_suspend_enabled = 1; |
1101 | EXPORT_SYMBOL(console_suspend_enabled); | |
1102 | ||
1103 | static int __init console_suspend_disable(char *str) | |
1104 | { | |
1105 | console_suspend_enabled = 0; | |
1106 | return 1; | |
1107 | } | |
1108 | __setup("no_console_suspend", console_suspend_disable); | |
1109 | ||
557240b4 LT |
1110 | /** |
1111 | * suspend_console - suspend the console subsystem | |
1112 | * | |
1113 | * This disables printk() while we go into suspend states | |
1114 | */ | |
1115 | void suspend_console(void) | |
1116 | { | |
8f4ce8c3 AS |
1117 | if (!console_suspend_enabled) |
1118 | return; | |
0d63081d | 1119 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
ac751efa | 1120 | console_lock(); |
557240b4 | 1121 | console_suspended = 1; |
403f3075 | 1122 | up(&console_sem); |
557240b4 LT |
1123 | } |
1124 | ||
1125 | void resume_console(void) | |
1126 | { | |
8f4ce8c3 AS |
1127 | if (!console_suspend_enabled) |
1128 | return; | |
403f3075 | 1129 | down(&console_sem); |
557240b4 | 1130 | console_suspended = 0; |
ac751efa | 1131 | console_unlock(); |
557240b4 LT |
1132 | } |
1133 | ||
034260d6 KC |
1134 | /** |
1135 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
1136 | * @self: notifier struct | |
1137 | * @action: CPU hotplug event | |
1138 | * @hcpu: unused | |
1139 | * | |
1140 | * If printk() is called from a CPU that is not online yet, the messages | |
1141 | * will be spooled but will not show up on the console. This function is | |
1142 | * called when a new CPU comes online (or fails to come up), and ensures | |
1143 | * that any such output gets printed. | |
1144 | */ | |
1145 | static int __cpuinit console_cpu_notify(struct notifier_block *self, | |
1146 | unsigned long action, void *hcpu) | |
1147 | { | |
1148 | switch (action) { | |
1149 | case CPU_ONLINE: | |
1150 | case CPU_DEAD: | |
1151 | case CPU_DYING: | |
1152 | case CPU_DOWN_FAILED: | |
1153 | case CPU_UP_CANCELED: | |
ac751efa TH |
1154 | console_lock(); |
1155 | console_unlock(); | |
034260d6 KC |
1156 | } |
1157 | return NOTIFY_OK; | |
1158 | } | |
1159 | ||
1da177e4 | 1160 | /** |
ac751efa | 1161 | * console_lock - lock the console system for exclusive use. |
1da177e4 | 1162 | * |
ac751efa | 1163 | * Acquires a lock which guarantees that the caller has |
1da177e4 LT |
1164 | * exclusive access to the console system and the console_drivers list. |
1165 | * | |
1166 | * Can sleep, returns nothing. | |
1167 | */ | |
ac751efa | 1168 | void console_lock(void) |
1da177e4 | 1169 | { |
8abd8e29 | 1170 | BUG_ON(in_interrupt()); |
1da177e4 | 1171 | down(&console_sem); |
403f3075 AH |
1172 | if (console_suspended) |
1173 | return; | |
1da177e4 LT |
1174 | console_locked = 1; |
1175 | console_may_schedule = 1; | |
1176 | } | |
ac751efa | 1177 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 1178 | |
ac751efa TH |
1179 | /** |
1180 | * console_trylock - try to lock the console system for exclusive use. | |
1181 | * | |
1182 | * Tried to acquire a lock which guarantees that the caller has | |
1183 | * exclusive access to the console system and the console_drivers list. | |
1184 | * | |
1185 | * returns 1 on success, and 0 on failure to acquire the lock. | |
1186 | */ | |
1187 | int console_trylock(void) | |
1da177e4 LT |
1188 | { |
1189 | if (down_trylock(&console_sem)) | |
ac751efa | 1190 | return 0; |
403f3075 AH |
1191 | if (console_suspended) { |
1192 | up(&console_sem); | |
ac751efa | 1193 | return 0; |
403f3075 | 1194 | } |
1da177e4 LT |
1195 | console_locked = 1; |
1196 | console_may_schedule = 0; | |
ac751efa | 1197 | return 1; |
1da177e4 | 1198 | } |
ac751efa | 1199 | EXPORT_SYMBOL(console_trylock); |
1da177e4 LT |
1200 | |
1201 | int is_console_locked(void) | |
1202 | { | |
1203 | return console_locked; | |
1204 | } | |
1da177e4 | 1205 | |
b845b517 PZ |
1206 | static DEFINE_PER_CPU(int, printk_pending); |
1207 | ||
1208 | void printk_tick(void) | |
e3e8a75d | 1209 | { |
40dc11ff ED |
1210 | if (__this_cpu_read(printk_pending)) { |
1211 | __this_cpu_write(printk_pending, 0); | |
e3e8a75d | 1212 | wake_up_interruptible(&log_wait); |
b845b517 PZ |
1213 | } |
1214 | } | |
1215 | ||
1216 | int printk_needs_cpu(int cpu) | |
1217 | { | |
40dc11ff | 1218 | if (cpu_is_offline(cpu)) |
61ab2544 | 1219 | printk_tick(); |
40dc11ff | 1220 | return __this_cpu_read(printk_pending); |
b845b517 PZ |
1221 | } |
1222 | ||
1223 | void wake_up_klogd(void) | |
1224 | { | |
1225 | if (waitqueue_active(&log_wait)) | |
49f41383 | 1226 | this_cpu_write(printk_pending, 1); |
e3e8a75d KK |
1227 | } |
1228 | ||
1da177e4 | 1229 | /** |
ac751efa | 1230 | * console_unlock - unlock the console system |
1da177e4 | 1231 | * |
ac751efa | 1232 | * Releases the console_lock which the caller holds on the console system |
1da177e4 LT |
1233 | * and the console driver list. |
1234 | * | |
ac751efa TH |
1235 | * While the console_lock was held, console output may have been buffered |
1236 | * by printk(). If this is the case, console_unlock(); emits | |
1237 | * the output prior to releasing the lock. | |
1da177e4 LT |
1238 | * |
1239 | * If there is output waiting for klogd, we wake it up. | |
1240 | * | |
ac751efa | 1241 | * console_unlock(); may be called from any context. |
1da177e4 | 1242 | */ |
ac751efa | 1243 | void console_unlock(void) |
1da177e4 LT |
1244 | { |
1245 | unsigned long flags; | |
eed4a2ab DV |
1246 | unsigned _con_start, _log_end; |
1247 | unsigned wake_klogd = 0; | |
1da177e4 | 1248 | |
557240b4 | 1249 | if (console_suspended) { |
403f3075 | 1250 | up(&console_sem); |
557240b4 LT |
1251 | return; |
1252 | } | |
78944e54 AD |
1253 | |
1254 | console_may_schedule = 0; | |
1255 | ||
1da177e4 LT |
1256 | for ( ; ; ) { |
1257 | spin_lock_irqsave(&logbuf_lock, flags); | |
1258 | wake_klogd |= log_start - log_end; | |
1259 | if (con_start == log_end) | |
1260 | break; /* Nothing to print */ | |
1261 | _con_start = con_start; | |
1262 | _log_end = log_end; | |
1263 | con_start = log_end; /* Flush */ | |
1264 | spin_unlock(&logbuf_lock); | |
81d68a96 | 1265 | stop_critical_timings(); /* don't trace print latency */ |
1da177e4 | 1266 | call_console_drivers(_con_start, _log_end); |
81d68a96 | 1267 | start_critical_timings(); |
1da177e4 LT |
1268 | local_irq_restore(flags); |
1269 | } | |
1270 | console_locked = 0; | |
fe3d8ad3 FT |
1271 | |
1272 | /* Release the exclusive_console once it is used */ | |
1273 | if (unlikely(exclusive_console)) | |
1274 | exclusive_console = NULL; | |
1275 | ||
1da177e4 | 1276 | spin_unlock_irqrestore(&logbuf_lock, flags); |
0b5e1c52 | 1277 | up(&console_sem); |
e3e8a75d KK |
1278 | if (wake_klogd) |
1279 | wake_up_klogd(); | |
1da177e4 | 1280 | } |
ac751efa | 1281 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 1282 | |
ddad86c2 MW |
1283 | /** |
1284 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1285 | * |
1286 | * If the console code is currently allowed to sleep, and | |
1287 | * if this CPU should yield the CPU to another task, do | |
1288 | * so here. | |
1289 | * | |
ac751efa | 1290 | * Must be called within console_lock();. |
1da177e4 LT |
1291 | */ |
1292 | void __sched console_conditional_schedule(void) | |
1293 | { | |
1294 | if (console_may_schedule) | |
1295 | cond_resched(); | |
1296 | } | |
1297 | EXPORT_SYMBOL(console_conditional_schedule); | |
1298 | ||
1da177e4 LT |
1299 | void console_unblank(void) |
1300 | { | |
1301 | struct console *c; | |
1302 | ||
1303 | /* | |
1304 | * console_unblank can no longer be called in interrupt context unless | |
1305 | * oops_in_progress is set to 1.. | |
1306 | */ | |
1307 | if (oops_in_progress) { | |
1308 | if (down_trylock(&console_sem) != 0) | |
1309 | return; | |
1310 | } else | |
ac751efa | 1311 | console_lock(); |
1da177e4 LT |
1312 | |
1313 | console_locked = 1; | |
1314 | console_may_schedule = 0; | |
4d091611 | 1315 | for_each_console(c) |
1da177e4 LT |
1316 | if ((c->flags & CON_ENABLED) && c->unblank) |
1317 | c->unblank(); | |
ac751efa | 1318 | console_unlock(); |
1da177e4 | 1319 | } |
1da177e4 LT |
1320 | |
1321 | /* | |
1322 | * Return the console tty driver structure and its associated index | |
1323 | */ | |
1324 | struct tty_driver *console_device(int *index) | |
1325 | { | |
1326 | struct console *c; | |
1327 | struct tty_driver *driver = NULL; | |
1328 | ||
ac751efa | 1329 | console_lock(); |
4d091611 | 1330 | for_each_console(c) { |
1da177e4 LT |
1331 | if (!c->device) |
1332 | continue; | |
1333 | driver = c->device(c, index); | |
1334 | if (driver) | |
1335 | break; | |
1336 | } | |
ac751efa | 1337 | console_unlock(); |
1da177e4 LT |
1338 | return driver; |
1339 | } | |
1340 | ||
1341 | /* | |
1342 | * Prevent further output on the passed console device so that (for example) | |
1343 | * serial drivers can disable console output before suspending a port, and can | |
1344 | * re-enable output afterwards. | |
1345 | */ | |
1346 | void console_stop(struct console *console) | |
1347 | { | |
ac751efa | 1348 | console_lock(); |
1da177e4 | 1349 | console->flags &= ~CON_ENABLED; |
ac751efa | 1350 | console_unlock(); |
1da177e4 LT |
1351 | } |
1352 | EXPORT_SYMBOL(console_stop); | |
1353 | ||
1354 | void console_start(struct console *console) | |
1355 | { | |
ac751efa | 1356 | console_lock(); |
1da177e4 | 1357 | console->flags |= CON_ENABLED; |
ac751efa | 1358 | console_unlock(); |
1da177e4 LT |
1359 | } |
1360 | EXPORT_SYMBOL(console_start); | |
1361 | ||
7bf69395 FDN |
1362 | static int __read_mostly keep_bootcon; |
1363 | ||
1364 | static int __init keep_bootcon_setup(char *str) | |
1365 | { | |
1366 | keep_bootcon = 1; | |
1367 | printk(KERN_INFO "debug: skip boot console de-registration.\n"); | |
1368 | ||
1369 | return 0; | |
1370 | } | |
1371 | ||
1372 | early_param("keep_bootcon", keep_bootcon_setup); | |
1373 | ||
1da177e4 LT |
1374 | /* |
1375 | * The console driver calls this routine during kernel initialization | |
1376 | * to register the console printing procedure with printk() and to | |
1377 | * print any messages that were printed by the kernel before the | |
1378 | * console driver was initialized. | |
4d091611 RG |
1379 | * |
1380 | * This can happen pretty early during the boot process (because of | |
1381 | * early_printk) - sometimes before setup_arch() completes - be careful | |
1382 | * of what kernel features are used - they may not be initialised yet. | |
1383 | * | |
1384 | * There are two types of consoles - bootconsoles (early_printk) and | |
1385 | * "real" consoles (everything which is not a bootconsole) which are | |
1386 | * handled differently. | |
1387 | * - Any number of bootconsoles can be registered at any time. | |
1388 | * - As soon as a "real" console is registered, all bootconsoles | |
1389 | * will be unregistered automatically. | |
1390 | * - Once a "real" console is registered, any attempt to register a | |
1391 | * bootconsoles will be rejected | |
1da177e4 | 1392 | */ |
4d091611 | 1393 | void register_console(struct console *newcon) |
1da177e4 | 1394 | { |
40dc5651 | 1395 | int i; |
1da177e4 | 1396 | unsigned long flags; |
4d091611 | 1397 | struct console *bcon = NULL; |
1da177e4 | 1398 | |
4d091611 RG |
1399 | /* |
1400 | * before we register a new CON_BOOT console, make sure we don't | |
1401 | * already have a valid console | |
1402 | */ | |
1403 | if (console_drivers && newcon->flags & CON_BOOT) { | |
1404 | /* find the last or real console */ | |
1405 | for_each_console(bcon) { | |
1406 | if (!(bcon->flags & CON_BOOT)) { | |
1407 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", | |
1408 | newcon->name, newcon->index); | |
1409 | return; | |
1410 | } | |
1411 | } | |
69331af7 GH |
1412 | } |
1413 | ||
4d091611 RG |
1414 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1415 | bcon = console_drivers; | |
1416 | ||
1417 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
1418 | preferred_console = selected_console; |
1419 | ||
4d091611 RG |
1420 | if (newcon->early_setup) |
1421 | newcon->early_setup(); | |
18a8bd94 | 1422 | |
1da177e4 LT |
1423 | /* |
1424 | * See if we want to use this console driver. If we | |
1425 | * didn't select a console we take the first one | |
1426 | * that registers here. | |
1427 | */ | |
1428 | if (preferred_console < 0) { | |
4d091611 RG |
1429 | if (newcon->index < 0) |
1430 | newcon->index = 0; | |
1431 | if (newcon->setup == NULL || | |
1432 | newcon->setup(newcon, NULL) == 0) { | |
1433 | newcon->flags |= CON_ENABLED; | |
1434 | if (newcon->device) { | |
1435 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
1436 | preferred_console = 0; |
1437 | } | |
1da177e4 LT |
1438 | } |
1439 | } | |
1440 | ||
1441 | /* | |
1442 | * See if this console matches one we selected on | |
1443 | * the command line. | |
1444 | */ | |
40dc5651 JJ |
1445 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1446 | i++) { | |
4d091611 | 1447 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1da177e4 | 1448 | continue; |
4d091611 RG |
1449 | if (newcon->index >= 0 && |
1450 | newcon->index != console_cmdline[i].index) | |
1da177e4 | 1451 | continue; |
4d091611 RG |
1452 | if (newcon->index < 0) |
1453 | newcon->index = console_cmdline[i].index; | |
f7511d5f ST |
1454 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1455 | if (console_cmdline[i].brl_options) { | |
4d091611 RG |
1456 | newcon->flags |= CON_BRL; |
1457 | braille_register_console(newcon, | |
f7511d5f ST |
1458 | console_cmdline[i].index, |
1459 | console_cmdline[i].options, | |
1460 | console_cmdline[i].brl_options); | |
1461 | return; | |
1462 | } | |
1463 | #endif | |
4d091611 RG |
1464 | if (newcon->setup && |
1465 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 1466 | break; |
4d091611 RG |
1467 | newcon->flags |= CON_ENABLED; |
1468 | newcon->index = console_cmdline[i].index; | |
ab4af03a | 1469 | if (i == selected_console) { |
4d091611 | 1470 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
1471 | preferred_console = selected_console; |
1472 | } | |
1da177e4 LT |
1473 | break; |
1474 | } | |
1475 | ||
4d091611 | 1476 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
1477 | return; |
1478 | ||
8259cf43 RG |
1479 | /* |
1480 | * If we have a bootconsole, and are switching to a real console, | |
1481 | * don't print everything out again, since when the boot console, and | |
1482 | * the real console are the same physical device, it's annoying to | |
1483 | * see the beginning boot messages twice | |
1484 | */ | |
1485 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 1486 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
1487 | |
1488 | /* | |
1489 | * Put this console in the list - keep the | |
1490 | * preferred driver at the head of the list. | |
1491 | */ | |
ac751efa | 1492 | console_lock(); |
4d091611 RG |
1493 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1494 | newcon->next = console_drivers; | |
1495 | console_drivers = newcon; | |
1496 | if (newcon->next) | |
1497 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 1498 | } else { |
4d091611 RG |
1499 | newcon->next = console_drivers->next; |
1500 | console_drivers->next = newcon; | |
1da177e4 | 1501 | } |
4d091611 | 1502 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 | 1503 | /* |
ac751efa | 1504 | * console_unlock(); will print out the buffered messages |
1da177e4 LT |
1505 | * for us. |
1506 | */ | |
1507 | spin_lock_irqsave(&logbuf_lock, flags); | |
1508 | con_start = log_start; | |
1509 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
fe3d8ad3 FT |
1510 | /* |
1511 | * We're about to replay the log buffer. Only do this to the | |
1512 | * just-registered console to avoid excessive message spam to | |
1513 | * the already-registered consoles. | |
1514 | */ | |
1515 | exclusive_console = newcon; | |
1da177e4 | 1516 | } |
ac751efa | 1517 | console_unlock(); |
fbc92a34 | 1518 | console_sysfs_notify(); |
8259cf43 RG |
1519 | |
1520 | /* | |
1521 | * By unregistering the bootconsoles after we enable the real console | |
1522 | * we get the "console xxx enabled" message on all the consoles - | |
1523 | * boot consoles, real consoles, etc - this is to ensure that end | |
1524 | * users know there might be something in the kernel's log buffer that | |
1525 | * went to the bootconsole (that they do not see on the real console) | |
1526 | */ | |
7bf69395 FDN |
1527 | if (bcon && |
1528 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && | |
1529 | !keep_bootcon) { | |
8259cf43 RG |
1530 | /* we need to iterate through twice, to make sure we print |
1531 | * everything out, before we unregister the console(s) | |
1532 | */ | |
1533 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", | |
1534 | newcon->name, newcon->index); | |
1535 | for_each_console(bcon) | |
1536 | if (bcon->flags & CON_BOOT) | |
1537 | unregister_console(bcon); | |
1538 | } else { | |
1539 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", | |
1540 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
1541 | newcon->name, newcon->index); | |
1542 | } | |
1da177e4 LT |
1543 | } |
1544 | EXPORT_SYMBOL(register_console); | |
1545 | ||
40dc5651 | 1546 | int unregister_console(struct console *console) |
1da177e4 | 1547 | { |
40dc5651 | 1548 | struct console *a, *b; |
1da177e4 LT |
1549 | int res = 1; |
1550 | ||
f7511d5f ST |
1551 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1552 | if (console->flags & CON_BRL) | |
1553 | return braille_unregister_console(console); | |
1554 | #endif | |
1555 | ||
ac751efa | 1556 | console_lock(); |
1da177e4 LT |
1557 | if (console_drivers == console) { |
1558 | console_drivers=console->next; | |
1559 | res = 0; | |
e9b15b54 | 1560 | } else if (console_drivers) { |
1da177e4 LT |
1561 | for (a=console_drivers->next, b=console_drivers ; |
1562 | a; b=a, a=b->next) { | |
1563 | if (a == console) { | |
1564 | b->next = a->next; | |
1565 | res = 0; | |
1566 | break; | |
40dc5651 | 1567 | } |
1da177e4 LT |
1568 | } |
1569 | } | |
40dc5651 | 1570 | |
69331af7 | 1571 | /* |
ab4af03a GE |
1572 | * If this isn't the last console and it has CON_CONSDEV set, we |
1573 | * need to set it on the next preferred console. | |
1da177e4 | 1574 | */ |
69331af7 | 1575 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1576 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 | 1577 | |
ac751efa | 1578 | console_unlock(); |
fbc92a34 | 1579 | console_sysfs_notify(); |
1da177e4 LT |
1580 | return res; |
1581 | } | |
1582 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1583 | |
034260d6 | 1584 | static int __init printk_late_init(void) |
0c5564bd | 1585 | { |
4d091611 RG |
1586 | struct console *con; |
1587 | ||
1588 | for_each_console(con) { | |
1589 | if (con->flags & CON_BOOT) { | |
cb00e99c | 1590 | printk(KERN_INFO "turn off boot console %s%d\n", |
4d091611 | 1591 | con->name, con->index); |
42c2c8c8 | 1592 | unregister_console(con); |
cb00e99c | 1593 | } |
0c5564bd | 1594 | } |
034260d6 | 1595 | hotcpu_notifier(console_cpu_notify, 0); |
0c5564bd RG |
1596 | return 0; |
1597 | } | |
034260d6 | 1598 | late_initcall(printk_late_init); |
0c5564bd | 1599 | |
7ef3d2fd | 1600 | #if defined CONFIG_PRINTK |
717115e1 | 1601 | |
1da177e4 LT |
1602 | /* |
1603 | * printk rate limiting, lifted from the networking subsystem. | |
1604 | * | |
641de9d8 UKK |
1605 | * This enforces a rate limit: not more than 10 kernel messages |
1606 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 1607 | */ |
641de9d8 UKK |
1608 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1609 | ||
5c828713 | 1610 | int __printk_ratelimit(const char *func) |
1da177e4 | 1611 | { |
5c828713 | 1612 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 1613 | } |
5c828713 | 1614 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
1615 | |
1616 | /** | |
1617 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1618 | * @caller_jiffies: pointer to caller's state | |
1619 | * @interval_msecs: minimum interval between prints | |
1620 | * | |
1621 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1622 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1623 | * returned true. | |
1624 | */ | |
1625 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1626 | unsigned int interval_msecs) | |
1627 | { | |
f2d28a2e GK |
1628 | if (*caller_jiffies == 0 |
1629 | || !time_in_range(jiffies, *caller_jiffies, | |
1630 | *caller_jiffies | |
1631 | + msecs_to_jiffies(interval_msecs))) { | |
1632 | *caller_jiffies = jiffies; | |
f46c4833 AM |
1633 | return true; |
1634 | } | |
1635 | return false; | |
1636 | } | |
1637 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
1638 | |
1639 | static DEFINE_SPINLOCK(dump_list_lock); | |
1640 | static LIST_HEAD(dump_list); | |
1641 | ||
1642 | /** | |
1643 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 1644 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1645 | * |
1646 | * Adds a kernel log dumper to the system. The dump callback in the | |
1647 | * structure will be called when the kernel oopses or panics and must be | |
1648 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
1649 | */ | |
1650 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
1651 | { | |
1652 | unsigned long flags; | |
1653 | int err = -EBUSY; | |
1654 | ||
1655 | /* The dump callback needs to be set */ | |
1656 | if (!dumper->dump) | |
1657 | return -EINVAL; | |
1658 | ||
1659 | spin_lock_irqsave(&dump_list_lock, flags); | |
1660 | /* Don't allow registering multiple times */ | |
1661 | if (!dumper->registered) { | |
1662 | dumper->registered = 1; | |
fb842b00 | 1663 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
1664 | err = 0; |
1665 | } | |
1666 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1667 | ||
1668 | return err; | |
1669 | } | |
1670 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
1671 | ||
1672 | /** | |
1673 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 1674 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1675 | * |
1676 | * Removes a dump device from the system. Returns zero on success and | |
1677 | * %-EINVAL otherwise. | |
1678 | */ | |
1679 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
1680 | { | |
1681 | unsigned long flags; | |
1682 | int err = -EINVAL; | |
1683 | ||
1684 | spin_lock_irqsave(&dump_list_lock, flags); | |
1685 | if (dumper->registered) { | |
1686 | dumper->registered = 0; | |
fb842b00 | 1687 | list_del_rcu(&dumper->list); |
456b565c SK |
1688 | err = 0; |
1689 | } | |
1690 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 1691 | synchronize_rcu(); |
456b565c SK |
1692 | |
1693 | return err; | |
1694 | } | |
1695 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
1696 | ||
456b565c SK |
1697 | /** |
1698 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
1699 | * @reason: the reason (oops, panic etc) for dumping | |
1700 | * | |
1701 | * Iterate through each of the dump devices and call the oops/panic | |
1702 | * callbacks with the log buffer. | |
1703 | */ | |
1704 | void kmsg_dump(enum kmsg_dump_reason reason) | |
1705 | { | |
1706 | unsigned long end; | |
1707 | unsigned chars; | |
1708 | struct kmsg_dumper *dumper; | |
1709 | const char *s1, *s2; | |
1710 | unsigned long l1, l2; | |
1711 | unsigned long flags; | |
1712 | ||
1713 | /* Theoretically, the log could move on after we do this, but | |
1714 | there's not a lot we can do about that. The new messages | |
1715 | will overwrite the start of what we dump. */ | |
1716 | spin_lock_irqsave(&logbuf_lock, flags); | |
1717 | end = log_end & LOG_BUF_MASK; | |
1718 | chars = logged_chars; | |
1719 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1720 | ||
8c4af38e AK |
1721 | if (chars > end) { |
1722 | s1 = log_buf + log_buf_len - chars + end; | |
1723 | l1 = chars - end; | |
456b565c SK |
1724 | |
1725 | s2 = log_buf; | |
1726 | l2 = end; | |
1727 | } else { | |
1728 | s1 = ""; | |
1729 | l1 = 0; | |
1730 | ||
8c4af38e AK |
1731 | s2 = log_buf + end - chars; |
1732 | l2 = chars; | |
456b565c SK |
1733 | } |
1734 | ||
fb842b00 HY |
1735 | rcu_read_lock(); |
1736 | list_for_each_entry_rcu(dumper, &dump_list, list) | |
456b565c | 1737 | dumper->dump(dumper, reason, s1, l1, s2, l2); |
fb842b00 | 1738 | rcu_read_unlock(); |
456b565c | 1739 | } |
7ef3d2fd | 1740 | #endif |