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> |
e11fea92 | 44 | #include <linux/poll.h> |
1da177e4 LT |
45 | |
46 | #include <asm/uaccess.h> | |
47 | ||
95100358 JB |
48 | #define CREATE_TRACE_POINTS |
49 | #include <trace/events/printk.h> | |
50 | ||
076f9776 IM |
51 | /* |
52 | * Architectures can override it: | |
53 | */ | |
e17ba73b | 54 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
076f9776 IM |
55 | { |
56 | } | |
57 | ||
1da177e4 | 58 | /* printk's without a loglevel use this.. */ |
5af5bcb8 | 59 | #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL |
1da177e4 LT |
60 | |
61 | /* We show everything that is MORE important than this.. */ | |
62 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
63 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
64 | ||
65 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
66 | ||
67 | int console_printk[4] = { | |
68 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
69 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
70 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
71 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
72 | }; | |
73 | ||
1da177e4 | 74 | /* |
0bbfb7c2 | 75 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
76 | * their unblank() callback or not. So let's export it. |
77 | */ | |
78 | int oops_in_progress; | |
79 | EXPORT_SYMBOL(oops_in_progress); | |
80 | ||
81 | /* | |
82 | * console_sem protects the console_drivers list, and also | |
83 | * provides serialisation for access to the entire console | |
84 | * driver system. | |
85 | */ | |
5b8c4f23 | 86 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 87 | struct console *console_drivers; |
a29d1cfe IM |
88 | EXPORT_SYMBOL_GPL(console_drivers); |
89 | ||
1da177e4 LT |
90 | /* |
91 | * This is used for debugging the mess that is the VT code by | |
92 | * keeping track if we have the console semaphore held. It's | |
93 | * definitely not the perfect debug tool (we don't know if _WE_ | |
94 | * hold it are racing, but it helps tracking those weird code | |
95 | * path in the console code where we end up in places I want | |
96 | * locked without the console sempahore held | |
97 | */ | |
557240b4 | 98 | static int console_locked, console_suspended; |
1da177e4 | 99 | |
fe3d8ad3 FT |
100 | /* |
101 | * If exclusive_console is non-NULL then only this console is to be printed to. | |
102 | */ | |
103 | static struct console *exclusive_console; | |
104 | ||
1da177e4 LT |
105 | /* |
106 | * Array of consoles built from command line options (console=) | |
107 | */ | |
108 | struct console_cmdline | |
109 | { | |
110 | char name[8]; /* Name of the driver */ | |
111 | int index; /* Minor dev. to use */ | |
112 | char *options; /* Options for the driver */ | |
f7511d5f ST |
113 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
114 | char *brl_options; /* Options for braille driver */ | |
115 | #endif | |
1da177e4 LT |
116 | }; |
117 | ||
118 | #define MAX_CMDLINECONSOLES 8 | |
119 | ||
120 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
121 | static int selected_console = -1; | |
122 | static int preferred_console = -1; | |
9e124fe1 MA |
123 | int console_set_on_cmdline; |
124 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
125 | |
126 | /* Flag: console code may call schedule() */ | |
127 | static int console_may_schedule; | |
128 | ||
7ff9554b KS |
129 | /* |
130 | * The printk log buffer consists of a chain of concatenated variable | |
131 | * length records. Every record starts with a record header, containing | |
132 | * the overall length of the record. | |
133 | * | |
134 | * The heads to the first and last entry in the buffer, as well as the | |
135 | * sequence numbers of these both entries are maintained when messages | |
136 | * are stored.. | |
137 | * | |
138 | * If the heads indicate available messages, the length in the header | |
139 | * tells the start next message. A length == 0 for the next message | |
140 | * indicates a wrap-around to the beginning of the buffer. | |
141 | * | |
142 | * Every record carries the monotonic timestamp in microseconds, as well as | |
143 | * the standard userspace syslog level and syslog facility. The usual | |
144 | * kernel messages use LOG_KERN; userspace-injected messages always carry | |
145 | * a matching syslog facility, by default LOG_USER. The origin of every | |
146 | * message can be reliably determined that way. | |
147 | * | |
148 | * The human readable log message directly follows the message header. The | |
149 | * length of the message text is stored in the header, the stored message | |
150 | * is not terminated. | |
151 | * | |
e11fea92 KS |
152 | * Optionally, a message can carry a dictionary of properties (key/value pairs), |
153 | * to provide userspace with a machine-readable message context. | |
154 | * | |
155 | * Examples for well-defined, commonly used property names are: | |
156 | * DEVICE=b12:8 device identifier | |
157 | * b12:8 block dev_t | |
158 | * c127:3 char dev_t | |
159 | * n8 netdev ifindex | |
160 | * +sound:card0 subsystem:devname | |
161 | * SUBSYSTEM=pci driver-core subsystem name | |
162 | * | |
163 | * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value | |
164 | * follows directly after a '=' character. Every property is terminated by | |
165 | * a '\0' character. The last property is not terminated. | |
166 | * | |
167 | * Example of a message structure: | |
168 | * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec | |
169 | * 0008 34 00 record is 52 bytes long | |
170 | * 000a 0b 00 text is 11 bytes long | |
171 | * 000c 1f 00 dictionary is 23 bytes long | |
172 | * 000e 03 00 LOG_KERN (facility) LOG_ERR (level) | |
173 | * 0010 69 74 27 73 20 61 20 6c "it's a l" | |
174 | * 69 6e 65 "ine" | |
175 | * 001b 44 45 56 49 43 "DEVIC" | |
176 | * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D" | |
177 | * 52 49 56 45 52 3d 62 75 "RIVER=bu" | |
178 | * 67 "g" | |
179 | * 0032 00 00 00 padding to next message header | |
180 | * | |
181 | * The 'struct log' buffer header must never be directly exported to | |
182 | * userspace, it is a kernel-private implementation detail that might | |
183 | * need to be changed in the future, when the requirements change. | |
184 | * | |
185 | * /dev/kmsg exports the structured data in the following line format: | |
186 | * "level,sequnum,timestamp;<message text>\n" | |
187 | * | |
188 | * The optional key/value pairs are attached as continuation lines starting | |
189 | * with a space character and terminated by a newline. All possible | |
190 | * non-prinatable characters are escaped in the "\xff" notation. | |
191 | * | |
192 | * Users of the export format should ignore possible additional values | |
193 | * separated by ',', and find the message after the ';' character. | |
7ff9554b KS |
194 | */ |
195 | ||
196 | struct log { | |
197 | u64 ts_nsec; /* timestamp in nanoseconds */ | |
198 | u16 len; /* length of entire record */ | |
199 | u16 text_len; /* length of text buffer */ | |
200 | u16 dict_len; /* length of dictionary buffer */ | |
201 | u16 level; /* syslog level + facility */ | |
202 | }; | |
203 | ||
204 | /* | |
205 | * The logbuf_lock protects kmsg buffer, indices, counters. It is also | |
206 | * used in interesting ways to provide interlocking in console_unlock(); | |
207 | */ | |
208 | static DEFINE_RAW_SPINLOCK(logbuf_lock); | |
d59745ce | 209 | |
7f3a781d KS |
210 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
211 | static u64 syslog_seq; | |
212 | static u32 syslog_idx; | |
7ff9554b KS |
213 | |
214 | /* index and sequence number of the first record stored in the buffer */ | |
215 | static u64 log_first_seq; | |
216 | static u32 log_first_idx; | |
217 | ||
218 | /* index and sequence number of the next record to store in the buffer */ | |
219 | static u64 log_next_seq; | |
7f3a781d | 220 | #ifdef CONFIG_PRINTK |
7ff9554b KS |
221 | static u32 log_next_idx; |
222 | ||
223 | /* the next printk record to read after the last 'clear' command */ | |
224 | static u64 clear_seq; | |
225 | static u32 clear_idx; | |
226 | ||
7f3a781d KS |
227 | #define LOG_LINE_MAX 1024 |
228 | ||
229 | /* record buffer */ | |
230 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) | |
231 | static char __log_buf[__LOG_BUF_LEN]; | |
232 | static char *log_buf = __log_buf; | |
233 | static u32 log_buf_len = __LOG_BUF_LEN; | |
234 | ||
235 | /* cpu currently holding logbuf_lock */ | |
236 | static volatile unsigned int logbuf_cpu = UINT_MAX; | |
7ff9554b KS |
237 | |
238 | /* human readable text of the record */ | |
239 | static char *log_text(const struct log *msg) | |
240 | { | |
241 | return (char *)msg + sizeof(struct log); | |
242 | } | |
243 | ||
244 | /* optional key/value pair dictionary attached to the record */ | |
245 | static char *log_dict(const struct log *msg) | |
246 | { | |
247 | return (char *)msg + sizeof(struct log) + msg->text_len; | |
248 | } | |
249 | ||
250 | /* get record by index; idx must point to valid msg */ | |
251 | static struct log *log_from_idx(u32 idx) | |
252 | { | |
253 | struct log *msg = (struct log *)(log_buf + idx); | |
254 | ||
255 | /* | |
256 | * A length == 0 record is the end of buffer marker. Wrap around and | |
257 | * read the message at the start of the buffer. | |
258 | */ | |
259 | if (!msg->len) | |
260 | return (struct log *)log_buf; | |
261 | return msg; | |
262 | } | |
263 | ||
264 | /* get next record; idx must point to valid msg */ | |
265 | static u32 log_next(u32 idx) | |
266 | { | |
267 | struct log *msg = (struct log *)(log_buf + idx); | |
268 | ||
269 | /* length == 0 indicates the end of the buffer; wrap */ | |
270 | /* | |
271 | * A length == 0 record is the end of buffer marker. Wrap around and | |
272 | * read the message at the start of the buffer as *this* one, and | |
273 | * return the one after that. | |
274 | */ | |
275 | if (!msg->len) { | |
276 | msg = (struct log *)log_buf; | |
277 | return msg->len; | |
278 | } | |
279 | return idx + msg->len; | |
280 | } | |
281 | ||
282 | #if !defined(CONFIG_64BIT) || defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) | |
283 | #define LOG_ALIGN 4 | |
284 | #else | |
285 | #define LOG_ALIGN 8 | |
286 | #endif | |
287 | ||
288 | /* insert record into the buffer, discard old ones, update heads */ | |
289 | static void log_store(int facility, int level, | |
290 | const char *dict, u16 dict_len, | |
291 | const char *text, u16 text_len) | |
292 | { | |
293 | struct log *msg; | |
294 | u32 size, pad_len; | |
295 | ||
296 | /* number of '\0' padding bytes to next message */ | |
297 | size = sizeof(struct log) + text_len + dict_len; | |
298 | pad_len = (-size) & (LOG_ALIGN - 1); | |
299 | size += pad_len; | |
300 | ||
301 | while (log_first_seq < log_next_seq) { | |
302 | u32 free; | |
303 | ||
304 | if (log_next_idx > log_first_idx) | |
305 | free = max(log_buf_len - log_next_idx, log_first_idx); | |
306 | else | |
307 | free = log_first_idx - log_next_idx; | |
308 | ||
309 | if (free > size + sizeof(struct log)) | |
310 | break; | |
311 | ||
312 | /* drop old messages until we have enough contiuous space */ | |
313 | log_first_idx = log_next(log_first_idx); | |
314 | log_first_seq++; | |
315 | } | |
316 | ||
317 | if (log_next_idx + size + sizeof(struct log) >= log_buf_len) { | |
318 | /* | |
319 | * This message + an additional empty header does not fit | |
320 | * at the end of the buffer. Add an empty header with len == 0 | |
321 | * to signify a wrap around. | |
322 | */ | |
323 | memset(log_buf + log_next_idx, 0, sizeof(struct log)); | |
324 | log_next_idx = 0; | |
325 | } | |
326 | ||
327 | /* fill message */ | |
328 | msg = (struct log *)(log_buf + log_next_idx); | |
329 | memcpy(log_text(msg), text, text_len); | |
330 | msg->text_len = text_len; | |
331 | memcpy(log_dict(msg), dict, dict_len); | |
332 | msg->dict_len = dict_len; | |
333 | msg->level = (facility << 3) | (level & 7); | |
334 | msg->ts_nsec = local_clock(); | |
335 | memset(log_dict(msg) + dict_len, 0, pad_len); | |
336 | msg->len = sizeof(struct log) + text_len + dict_len + pad_len; | |
337 | ||
338 | /* insert message */ | |
339 | log_next_idx += msg->len; | |
340 | log_next_seq++; | |
341 | } | |
d59745ce | 342 | |
e11fea92 KS |
343 | /* /dev/kmsg - userspace message inject/listen interface */ |
344 | struct devkmsg_user { | |
345 | u64 seq; | |
346 | u32 idx; | |
347 | struct mutex lock; | |
348 | char buf[8192]; | |
349 | }; | |
350 | ||
351 | static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv, | |
352 | unsigned long count, loff_t pos) | |
353 | { | |
354 | char *buf, *line; | |
355 | int i; | |
356 | int level = default_message_loglevel; | |
357 | int facility = 1; /* LOG_USER */ | |
358 | size_t len = iov_length(iv, count); | |
359 | ssize_t ret = len; | |
360 | ||
361 | if (len > LOG_LINE_MAX) | |
362 | return -EINVAL; | |
363 | buf = kmalloc(len+1, GFP_KERNEL); | |
364 | if (buf == NULL) | |
365 | return -ENOMEM; | |
366 | ||
367 | line = buf; | |
368 | for (i = 0; i < count; i++) { | |
369 | if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) | |
370 | goto out; | |
371 | line += iv[i].iov_len; | |
372 | } | |
373 | ||
374 | /* | |
375 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace | |
376 | * the decimal value represents 32bit, the lower 3 bit are the log | |
377 | * level, the rest are the log facility. | |
378 | * | |
379 | * If no prefix or no userspace facility is specified, we | |
380 | * enforce LOG_USER, to be able to reliably distinguish | |
381 | * kernel-generated messages from userspace-injected ones. | |
382 | */ | |
383 | line = buf; | |
384 | if (line[0] == '<') { | |
385 | char *endp = NULL; | |
386 | ||
387 | i = simple_strtoul(line+1, &endp, 10); | |
388 | if (endp && endp[0] == '>') { | |
389 | level = i & 7; | |
390 | if (i >> 3) | |
391 | facility = i >> 3; | |
392 | endp++; | |
393 | len -= endp - line; | |
394 | line = endp; | |
395 | } | |
396 | } | |
397 | line[len] = '\0'; | |
398 | ||
399 | printk_emit(facility, level, NULL, 0, "%s", line); | |
400 | out: | |
401 | kfree(buf); | |
402 | return ret; | |
403 | } | |
404 | ||
405 | static ssize_t devkmsg_read(struct file *file, char __user *buf, | |
406 | size_t count, loff_t *ppos) | |
407 | { | |
408 | struct devkmsg_user *user = file->private_data; | |
409 | struct log *msg; | |
5fc32490 | 410 | u64 ts_usec; |
e11fea92 KS |
411 | size_t i; |
412 | size_t len; | |
413 | ssize_t ret; | |
414 | ||
415 | if (!user) | |
416 | return -EBADF; | |
417 | ||
418 | mutex_lock(&user->lock); | |
419 | raw_spin_lock(&logbuf_lock); | |
420 | while (user->seq == log_next_seq) { | |
421 | if (file->f_flags & O_NONBLOCK) { | |
422 | ret = -EAGAIN; | |
423 | raw_spin_unlock(&logbuf_lock); | |
424 | goto out; | |
425 | } | |
426 | ||
427 | raw_spin_unlock(&logbuf_lock); | |
428 | ret = wait_event_interruptible(log_wait, | |
429 | user->seq != log_next_seq); | |
430 | if (ret) | |
431 | goto out; | |
432 | raw_spin_lock(&logbuf_lock); | |
433 | } | |
434 | ||
435 | if (user->seq < log_first_seq) { | |
436 | /* our last seen message is gone, return error and reset */ | |
437 | user->idx = log_first_idx; | |
438 | user->seq = log_first_seq; | |
439 | ret = -EPIPE; | |
440 | raw_spin_unlock(&logbuf_lock); | |
441 | goto out; | |
442 | } | |
443 | ||
444 | msg = log_from_idx(user->idx); | |
5fc32490 KS |
445 | ts_usec = msg->ts_nsec; |
446 | do_div(ts_usec, 1000); | |
e11fea92 | 447 | len = sprintf(user->buf, "%u,%llu,%llu;", |
5fc32490 | 448 | msg->level, user->seq, ts_usec); |
e11fea92 KS |
449 | |
450 | /* escape non-printable characters */ | |
451 | for (i = 0; i < msg->text_len; i++) { | |
452 | char c = log_text(msg)[i]; | |
453 | ||
454 | if (c < ' ' || c >= 128) | |
455 | len += sprintf(user->buf + len, "\\x%02x", c); | |
456 | else | |
457 | user->buf[len++] = c; | |
458 | } | |
459 | user->buf[len++] = '\n'; | |
460 | ||
461 | if (msg->dict_len) { | |
462 | bool line = true; | |
463 | ||
464 | for (i = 0; i < msg->dict_len; i++) { | |
465 | char c = log_dict(msg)[i]; | |
466 | ||
467 | if (line) { | |
468 | user->buf[len++] = ' '; | |
469 | line = false; | |
470 | } | |
471 | ||
472 | if (c == '\0') { | |
473 | user->buf[len++] = '\n'; | |
474 | line = true; | |
475 | continue; | |
476 | } | |
477 | ||
478 | if (c < ' ' || c >= 128) { | |
479 | len += sprintf(user->buf + len, "\\x%02x", c); | |
480 | continue; | |
481 | } | |
482 | ||
483 | user->buf[len++] = c; | |
484 | } | |
485 | user->buf[len++] = '\n'; | |
486 | } | |
487 | ||
488 | user->idx = log_next(user->idx); | |
489 | user->seq++; | |
490 | raw_spin_unlock(&logbuf_lock); | |
491 | ||
492 | if (len > count) { | |
493 | ret = -EINVAL; | |
494 | goto out; | |
495 | } | |
496 | ||
497 | if (copy_to_user(buf, user->buf, len)) { | |
498 | ret = -EFAULT; | |
499 | goto out; | |
500 | } | |
501 | ret = len; | |
502 | out: | |
503 | mutex_unlock(&user->lock); | |
504 | return ret; | |
505 | } | |
506 | ||
507 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) | |
508 | { | |
509 | struct devkmsg_user *user = file->private_data; | |
510 | loff_t ret = 0; | |
511 | ||
512 | if (!user) | |
513 | return -EBADF; | |
514 | if (offset) | |
515 | return -ESPIPE; | |
516 | ||
517 | raw_spin_lock(&logbuf_lock); | |
518 | switch (whence) { | |
519 | case SEEK_SET: | |
520 | /* the first record */ | |
521 | user->idx = log_first_idx; | |
522 | user->seq = log_first_seq; | |
523 | break; | |
524 | case SEEK_DATA: | |
525 | /* | |
526 | * The first record after the last SYSLOG_ACTION_CLEAR, | |
527 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself | |
528 | * changes no global state, and does not clear anything. | |
529 | */ | |
530 | user->idx = clear_idx; | |
531 | user->seq = clear_seq; | |
532 | break; | |
533 | case SEEK_END: | |
534 | /* after the last record */ | |
535 | user->idx = log_next_idx; | |
536 | user->seq = log_next_seq; | |
537 | break; | |
538 | default: | |
539 | ret = -EINVAL; | |
540 | } | |
541 | raw_spin_unlock(&logbuf_lock); | |
542 | return ret; | |
543 | } | |
544 | ||
545 | static unsigned int devkmsg_poll(struct file *file, poll_table *wait) | |
546 | { | |
547 | struct devkmsg_user *user = file->private_data; | |
548 | int ret = 0; | |
549 | ||
550 | if (!user) | |
551 | return POLLERR|POLLNVAL; | |
552 | ||
553 | poll_wait(file, &log_wait, wait); | |
554 | ||
555 | raw_spin_lock(&logbuf_lock); | |
556 | if (user->seq < log_next_seq) { | |
557 | /* return error when data has vanished underneath us */ | |
558 | if (user->seq < log_first_seq) | |
559 | ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI; | |
560 | ret = POLLIN|POLLRDNORM; | |
561 | } | |
562 | raw_spin_unlock(&logbuf_lock); | |
563 | ||
564 | return ret; | |
565 | } | |
566 | ||
567 | static int devkmsg_open(struct inode *inode, struct file *file) | |
568 | { | |
569 | struct devkmsg_user *user; | |
570 | int err; | |
571 | ||
572 | /* write-only does not need any file context */ | |
573 | if ((file->f_flags & O_ACCMODE) == O_WRONLY) | |
574 | return 0; | |
575 | ||
576 | err = security_syslog(SYSLOG_ACTION_READ_ALL); | |
577 | if (err) | |
578 | return err; | |
579 | ||
580 | user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); | |
581 | if (!user) | |
582 | return -ENOMEM; | |
583 | ||
584 | mutex_init(&user->lock); | |
585 | ||
586 | raw_spin_lock(&logbuf_lock); | |
587 | user->idx = log_first_idx; | |
588 | user->seq = log_first_seq; | |
589 | raw_spin_unlock(&logbuf_lock); | |
590 | ||
591 | file->private_data = user; | |
592 | return 0; | |
593 | } | |
594 | ||
595 | static int devkmsg_release(struct inode *inode, struct file *file) | |
596 | { | |
597 | struct devkmsg_user *user = file->private_data; | |
598 | ||
599 | if (!user) | |
600 | return 0; | |
601 | ||
602 | mutex_destroy(&user->lock); | |
603 | kfree(user); | |
604 | return 0; | |
605 | } | |
606 | ||
607 | const struct file_operations kmsg_fops = { | |
608 | .open = devkmsg_open, | |
609 | .read = devkmsg_read, | |
610 | .aio_write = devkmsg_writev, | |
611 | .llseek = devkmsg_llseek, | |
612 | .poll = devkmsg_poll, | |
613 | .release = devkmsg_release, | |
614 | }; | |
615 | ||
04d491ab NH |
616 | #ifdef CONFIG_KEXEC |
617 | /* | |
618 | * This appends the listed symbols to /proc/vmcoreinfo | |
619 | * | |
620 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
621 | * obtain access to symbols that are otherwise very difficult to locate. These | |
622 | * symbols are specifically used so that utilities can access and extract the | |
623 | * dmesg log from a vmcore file after a crash. | |
624 | */ | |
625 | void log_buf_kexec_setup(void) | |
626 | { | |
627 | VMCOREINFO_SYMBOL(log_buf); | |
04d491ab | 628 | VMCOREINFO_SYMBOL(log_buf_len); |
7ff9554b KS |
629 | VMCOREINFO_SYMBOL(log_first_idx); |
630 | VMCOREINFO_SYMBOL(log_next_idx); | |
04d491ab NH |
631 | } |
632 | #endif | |
633 | ||
162a7e75 MT |
634 | /* requested log_buf_len from kernel cmdline */ |
635 | static unsigned long __initdata new_log_buf_len; | |
636 | ||
637 | /* save requested log_buf_len since it's too early to process it */ | |
1da177e4 LT |
638 | static int __init log_buf_len_setup(char *str) |
639 | { | |
eed4a2ab | 640 | unsigned size = memparse(str, &str); |
1da177e4 LT |
641 | |
642 | if (size) | |
643 | size = roundup_pow_of_two(size); | |
162a7e75 MT |
644 | if (size > log_buf_len) |
645 | new_log_buf_len = size; | |
646 | ||
647 | return 0; | |
1da177e4 | 648 | } |
162a7e75 MT |
649 | early_param("log_buf_len", log_buf_len_setup); |
650 | ||
651 | void __init setup_log_buf(int early) | |
652 | { | |
653 | unsigned long flags; | |
162a7e75 MT |
654 | char *new_log_buf; |
655 | int free; | |
656 | ||
657 | if (!new_log_buf_len) | |
658 | return; | |
1da177e4 | 659 | |
162a7e75 MT |
660 | if (early) { |
661 | unsigned long mem; | |
662 | ||
663 | mem = memblock_alloc(new_log_buf_len, PAGE_SIZE); | |
1f5026a7 | 664 | if (!mem) |
162a7e75 MT |
665 | return; |
666 | new_log_buf = __va(mem); | |
667 | } else { | |
668 | new_log_buf = alloc_bootmem_nopanic(new_log_buf_len); | |
669 | } | |
670 | ||
671 | if (unlikely(!new_log_buf)) { | |
672 | pr_err("log_buf_len: %ld bytes not available\n", | |
673 | new_log_buf_len); | |
674 | return; | |
675 | } | |
676 | ||
07354eb1 | 677 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
162a7e75 MT |
678 | log_buf_len = new_log_buf_len; |
679 | log_buf = new_log_buf; | |
680 | new_log_buf_len = 0; | |
7ff9554b KS |
681 | free = __LOG_BUF_LEN - log_next_idx; |
682 | memcpy(log_buf, __log_buf, __LOG_BUF_LEN); | |
07354eb1 | 683 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
162a7e75 MT |
684 | |
685 | pr_info("log_buf_len: %d\n", log_buf_len); | |
686 | pr_info("early log buf free: %d(%d%%)\n", | |
687 | free, (free * 100) / __LOG_BUF_LEN); | |
688 | } | |
1da177e4 | 689 | |
bfe8df3d RD |
690 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
691 | ||
674dff65 | 692 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 693 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
694 | |
695 | static int __init boot_delay_setup(char *str) | |
696 | { | |
697 | unsigned long lpj; | |
bfe8df3d RD |
698 | |
699 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
700 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
701 | ||
702 | get_option(&str, &boot_delay); | |
703 | if (boot_delay > 10 * 1000) | |
704 | boot_delay = 0; | |
705 | ||
3a3b6ed2 DY |
706 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
707 | "HZ: %d, loops_per_msec: %llu\n", | |
708 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
bfe8df3d RD |
709 | return 1; |
710 | } | |
711 | __setup("boot_delay=", boot_delay_setup); | |
712 | ||
713 | static void boot_delay_msec(void) | |
714 | { | |
715 | unsigned long long k; | |
716 | unsigned long timeout; | |
717 | ||
718 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
719 | return; | |
720 | ||
3a3b6ed2 | 721 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
722 | |
723 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
724 | while (k) { | |
725 | k--; | |
726 | cpu_relax(); | |
727 | /* | |
728 | * use (volatile) jiffies to prevent | |
729 | * compiler reduction; loop termination via jiffies | |
730 | * is secondary and may or may not happen. | |
731 | */ | |
732 | if (time_after(jiffies, timeout)) | |
733 | break; | |
734 | touch_nmi_watchdog(); | |
735 | } | |
736 | } | |
737 | #else | |
738 | static inline void boot_delay_msec(void) | |
739 | { | |
740 | } | |
741 | #endif | |
742 | ||
eaf06b24 DR |
743 | #ifdef CONFIG_SECURITY_DMESG_RESTRICT |
744 | int dmesg_restrict = 1; | |
745 | #else | |
746 | int dmesg_restrict; | |
747 | #endif | |
748 | ||
ee24aebf LT |
749 | static int syslog_action_restricted(int type) |
750 | { | |
751 | if (dmesg_restrict) | |
752 | return 1; | |
753 | /* Unless restricted, we allow "read all" and "get buffer size" for everybody */ | |
754 | return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; | |
755 | } | |
756 | ||
757 | static int check_syslog_permissions(int type, bool from_file) | |
758 | { | |
759 | /* | |
760 | * If this is from /proc/kmsg and we've already opened it, then we've | |
761 | * already done the capabilities checks at open time. | |
762 | */ | |
763 | if (from_file && type != SYSLOG_ACTION_OPEN) | |
764 | return 0; | |
765 | ||
766 | if (syslog_action_restricted(type)) { | |
767 | if (capable(CAP_SYSLOG)) | |
768 | return 0; | |
769 | /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */ | |
770 | if (capable(CAP_SYS_ADMIN)) { | |
f2c0d026 JN |
771 | printk_once(KERN_WARNING "%s (%d): " |
772 | "Attempt to access syslog with CAP_SYS_ADMIN " | |
773 | "but no CAP_SYSLOG (deprecated).\n", | |
774 | current->comm, task_pid_nr(current)); | |
ee24aebf LT |
775 | return 0; |
776 | } | |
777 | return -EPERM; | |
778 | } | |
779 | return 0; | |
780 | } | |
781 | ||
7ff9554b KS |
782 | #if defined(CONFIG_PRINTK_TIME) |
783 | static bool printk_time = 1; | |
784 | #else | |
785 | static bool printk_time; | |
786 | #endif | |
787 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); | |
788 | ||
649e6ee3 KS |
789 | static size_t prepend_timestamp(unsigned long long t, char *buf) |
790 | { | |
791 | unsigned long rem_ns; | |
792 | ||
793 | if (!printk_time) | |
794 | return 0; | |
795 | ||
796 | if (!buf) | |
797 | return 15; | |
798 | ||
799 | rem_ns = do_div(t, 1000000000); | |
800 | ||
801 | return sprintf(buf, "[%5lu.%06lu] ", | |
802 | (unsigned long) t, rem_ns / 1000); | |
803 | } | |
804 | ||
7ff9554b KS |
805 | static int syslog_print_line(u32 idx, char *text, size_t size) |
806 | { | |
807 | struct log *msg; | |
808 | size_t len; | |
809 | ||
810 | msg = log_from_idx(idx); | |
811 | if (!text) { | |
812 | /* calculate length only */ | |
813 | len = 3; | |
814 | ||
815 | if (msg->level > 9) | |
816 | len++; | |
817 | if (msg->level > 99) | |
818 | len++; | |
649e6ee3 | 819 | len += prepend_timestamp(0, NULL); |
7ff9554b KS |
820 | |
821 | len += msg->text_len; | |
822 | len++; | |
823 | return len; | |
824 | } | |
825 | ||
826 | len = sprintf(text, "<%u>", msg->level); | |
649e6ee3 | 827 | len += prepend_timestamp(msg->ts_nsec, text + len); |
7ff9554b KS |
828 | if (len + msg->text_len > size) |
829 | return -EINVAL; | |
830 | memcpy(text + len, log_text(msg), msg->text_len); | |
831 | len += msg->text_len; | |
832 | text[len++] = '\n'; | |
833 | return len; | |
834 | } | |
835 | ||
836 | static int syslog_print(char __user *buf, int size) | |
837 | { | |
838 | char *text; | |
839 | int len; | |
840 | ||
841 | text = kmalloc(LOG_LINE_MAX, GFP_KERNEL); | |
842 | if (!text) | |
843 | return -ENOMEM; | |
844 | ||
845 | raw_spin_lock_irq(&logbuf_lock); | |
846 | if (syslog_seq < log_first_seq) { | |
847 | /* messages are gone, move to first one */ | |
848 | syslog_seq = log_first_seq; | |
849 | syslog_idx = log_first_idx; | |
850 | } | |
851 | len = syslog_print_line(syslog_idx, text, LOG_LINE_MAX); | |
852 | syslog_idx = log_next(syslog_idx); | |
853 | syslog_seq++; | |
854 | raw_spin_unlock_irq(&logbuf_lock); | |
855 | ||
856 | if (len > 0 && copy_to_user(buf, text, len)) | |
857 | len = -EFAULT; | |
858 | ||
859 | kfree(text); | |
860 | return len; | |
861 | } | |
862 | ||
863 | static int syslog_print_all(char __user *buf, int size, bool clear) | |
864 | { | |
865 | char *text; | |
866 | int len = 0; | |
867 | ||
868 | text = kmalloc(LOG_LINE_MAX, GFP_KERNEL); | |
869 | if (!text) | |
870 | return -ENOMEM; | |
871 | ||
872 | raw_spin_lock_irq(&logbuf_lock); | |
873 | if (buf) { | |
874 | u64 next_seq; | |
875 | u64 seq; | |
876 | u32 idx; | |
877 | ||
878 | if (clear_seq < log_first_seq) { | |
879 | /* messages are gone, move to first available one */ | |
880 | clear_seq = log_first_seq; | |
881 | clear_idx = log_first_idx; | |
882 | } | |
883 | ||
884 | /* | |
885 | * Find first record that fits, including all following records, | |
886 | * into the user-provided buffer for this dump. | |
887 | */ | |
888 | seq = clear_seq; | |
889 | idx = clear_idx; | |
890 | while (seq < log_next_seq) { | |
891 | len += syslog_print_line(idx, NULL, 0); | |
892 | idx = log_next(idx); | |
893 | seq++; | |
894 | } | |
895 | seq = clear_seq; | |
896 | idx = clear_idx; | |
897 | while (len > size && seq < log_next_seq) { | |
898 | len -= syslog_print_line(idx, NULL, 0); | |
899 | idx = log_next(idx); | |
900 | seq++; | |
901 | } | |
902 | ||
903 | /* last message in this dump */ | |
904 | next_seq = log_next_seq; | |
905 | ||
906 | len = 0; | |
907 | while (len >= 0 && seq < next_seq) { | |
908 | int textlen; | |
909 | ||
910 | textlen = syslog_print_line(idx, text, LOG_LINE_MAX); | |
911 | if (textlen < 0) { | |
912 | len = textlen; | |
913 | break; | |
914 | } | |
915 | idx = log_next(idx); | |
916 | seq++; | |
917 | ||
918 | raw_spin_unlock_irq(&logbuf_lock); | |
919 | if (copy_to_user(buf + len, text, textlen)) | |
920 | len = -EFAULT; | |
921 | else | |
922 | len += textlen; | |
923 | raw_spin_lock_irq(&logbuf_lock); | |
924 | ||
925 | if (seq < log_first_seq) { | |
926 | /* messages are gone, move to next one */ | |
927 | seq = log_first_seq; | |
928 | idx = log_first_idx; | |
929 | } | |
930 | } | |
931 | } | |
932 | ||
933 | if (clear) { | |
934 | clear_seq = log_next_seq; | |
935 | clear_idx = log_next_idx; | |
936 | } | |
937 | raw_spin_unlock_irq(&logbuf_lock); | |
938 | ||
939 | kfree(text); | |
940 | return len; | |
941 | } | |
942 | ||
00234592 | 943 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
1da177e4 | 944 | { |
7ff9554b KS |
945 | bool clear = false; |
946 | static int saved_console_loglevel = -1; | |
ee24aebf | 947 | int error; |
1da177e4 | 948 | |
ee24aebf LT |
949 | error = check_syslog_permissions(type, from_file); |
950 | if (error) | |
951 | goto out; | |
12b3052c EP |
952 | |
953 | error = security_syslog(type); | |
1da177e4 LT |
954 | if (error) |
955 | return error; | |
956 | ||
957 | switch (type) { | |
d78ca3cd | 958 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 959 | break; |
d78ca3cd | 960 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 961 | break; |
d78ca3cd | 962 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 LT |
963 | error = -EINVAL; |
964 | if (!buf || len < 0) | |
965 | goto out; | |
966 | error = 0; | |
967 | if (!len) | |
968 | goto out; | |
969 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
970 | error = -EFAULT; | |
971 | goto out; | |
972 | } | |
40dc5651 | 973 | error = wait_event_interruptible(log_wait, |
7ff9554b | 974 | syslog_seq != log_next_seq); |
1da177e4 LT |
975 | if (error) |
976 | goto out; | |
7ff9554b | 977 | error = syslog_print(buf, len); |
1da177e4 | 978 | break; |
d78ca3cd KC |
979 | /* Read/clear last kernel messages */ |
980 | case SYSLOG_ACTION_READ_CLEAR: | |
7ff9554b | 981 | clear = true; |
1da177e4 | 982 | /* FALL THRU */ |
d78ca3cd KC |
983 | /* Read last kernel messages */ |
984 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 LT |
985 | error = -EINVAL; |
986 | if (!buf || len < 0) | |
987 | goto out; | |
988 | error = 0; | |
989 | if (!len) | |
990 | goto out; | |
991 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
992 | error = -EFAULT; | |
993 | goto out; | |
994 | } | |
7ff9554b | 995 | error = syslog_print_all(buf, len, clear); |
1da177e4 | 996 | break; |
d78ca3cd KC |
997 | /* Clear ring buffer */ |
998 | case SYSLOG_ACTION_CLEAR: | |
7ff9554b | 999 | syslog_print_all(NULL, 0, true); |
d78ca3cd KC |
1000 | /* Disable logging to console */ |
1001 | case SYSLOG_ACTION_CONSOLE_OFF: | |
1aaad49e FP |
1002 | if (saved_console_loglevel == -1) |
1003 | saved_console_loglevel = console_loglevel; | |
1da177e4 LT |
1004 | console_loglevel = minimum_console_loglevel; |
1005 | break; | |
d78ca3cd KC |
1006 | /* Enable logging to console */ |
1007 | case SYSLOG_ACTION_CONSOLE_ON: | |
1aaad49e FP |
1008 | if (saved_console_loglevel != -1) { |
1009 | console_loglevel = saved_console_loglevel; | |
1010 | saved_console_loglevel = -1; | |
1011 | } | |
1da177e4 | 1012 | break; |
d78ca3cd KC |
1013 | /* Set level of messages printed to console */ |
1014 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 LT |
1015 | error = -EINVAL; |
1016 | if (len < 1 || len > 8) | |
1017 | goto out; | |
1018 | if (len < minimum_console_loglevel) | |
1019 | len = minimum_console_loglevel; | |
1020 | console_loglevel = len; | |
1aaad49e FP |
1021 | /* Implicitly re-enable logging to console */ |
1022 | saved_console_loglevel = -1; | |
1da177e4 LT |
1023 | error = 0; |
1024 | break; | |
d78ca3cd KC |
1025 | /* Number of chars in the log buffer */ |
1026 | case SYSLOG_ACTION_SIZE_UNREAD: | |
7ff9554b KS |
1027 | raw_spin_lock_irq(&logbuf_lock); |
1028 | if (syslog_seq < log_first_seq) { | |
1029 | /* messages are gone, move to first one */ | |
1030 | syslog_seq = log_first_seq; | |
1031 | syslog_idx = log_first_idx; | |
1032 | } | |
1033 | if (from_file) { | |
1034 | /* | |
1035 | * Short-cut for poll(/"proc/kmsg") which simply checks | |
1036 | * for pending data, not the size; return the count of | |
1037 | * records, not the length. | |
1038 | */ | |
1039 | error = log_next_idx - syslog_idx; | |
1040 | } else { | |
1041 | u64 seq; | |
1042 | u32 idx; | |
1043 | ||
1044 | error = 0; | |
1045 | seq = syslog_seq; | |
1046 | idx = syslog_idx; | |
1047 | while (seq < log_next_seq) { | |
1048 | error += syslog_print_line(idx, NULL, 0); | |
1049 | idx = log_next(idx); | |
1050 | seq++; | |
1051 | } | |
1052 | } | |
1053 | raw_spin_unlock_irq(&logbuf_lock); | |
1da177e4 | 1054 | break; |
d78ca3cd KC |
1055 | /* Size of the log buffer */ |
1056 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
1057 | error = log_buf_len; |
1058 | break; | |
1059 | default: | |
1060 | error = -EINVAL; | |
1061 | break; | |
1062 | } | |
1063 | out: | |
1064 | return error; | |
1065 | } | |
1066 | ||
1e7bfb21 | 1067 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 1068 | { |
00234592 | 1069 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
1da177e4 LT |
1070 | } |
1071 | ||
67fc4e0c JW |
1072 | #ifdef CONFIG_KGDB_KDB |
1073 | /* kdb dmesg command needs access to the syslog buffer. do_syslog() | |
1074 | * uses locks so it cannot be used during debugging. Just tell kdb | |
1075 | * where the start and end of the physical and logical logs are. This | |
1076 | * is equivalent to do_syslog(3). | |
1077 | */ | |
1078 | void kdb_syslog_data(char *syslog_data[4]) | |
1079 | { | |
1080 | syslog_data[0] = log_buf; | |
1081 | syslog_data[1] = log_buf + log_buf_len; | |
7ff9554b KS |
1082 | syslog_data[2] = log_buf + log_first_idx; |
1083 | syslog_data[3] = log_buf + log_next_idx; | |
67fc4e0c JW |
1084 | } |
1085 | #endif /* CONFIG_KGDB_KDB */ | |
1086 | ||
2329abfa | 1087 | static bool __read_mostly ignore_loglevel; |
79290822 | 1088 | |
99eea6a1 | 1089 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
1090 | { |
1091 | ignore_loglevel = 1; | |
1092 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
1093 | ||
c4772d99 | 1094 | return 0; |
79290822 IM |
1095 | } |
1096 | ||
c4772d99 | 1097 | early_param("ignore_loglevel", ignore_loglevel_setup); |
29d4d6df | 1098 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); |
0eca6b7c YZ |
1099 | MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to" |
1100 | "print all kernel messages to the console."); | |
79290822 | 1101 | |
1da177e4 LT |
1102 | /* |
1103 | * Call the console drivers, asking them to write out | |
1104 | * log_buf[start] to log_buf[end - 1]. | |
ac751efa | 1105 | * The console_lock must be held. |
1da177e4 | 1106 | */ |
7ff9554b | 1107 | static void call_console_drivers(int level, const char *text, size_t len) |
1da177e4 | 1108 | { |
7ff9554b | 1109 | struct console *con; |
1da177e4 | 1110 | |
7ff9554b KS |
1111 | trace_console(text, 0, len, len); |
1112 | ||
1113 | if (level >= console_loglevel && !ignore_loglevel) | |
1114 | return; | |
1115 | if (!console_drivers) | |
1116 | return; | |
1117 | ||
1118 | for_each_console(con) { | |
1119 | if (exclusive_console && con != exclusive_console) | |
1120 | continue; | |
1121 | if (!(con->flags & CON_ENABLED)) | |
1122 | continue; | |
1123 | if (!con->write) | |
1124 | continue; | |
1125 | if (!cpu_online(smp_processor_id()) && | |
1126 | !(con->flags & CON_ANYTIME)) | |
1127 | continue; | |
1128 | con->write(con, text, len); | |
1129 | } | |
1da177e4 LT |
1130 | } |
1131 | ||
1132 | /* | |
1133 | * Zap console related locks when oopsing. Only zap at most once | |
1134 | * every 10 seconds, to leave time for slow consoles to print a | |
1135 | * full oops. | |
1136 | */ | |
1137 | static void zap_locks(void) | |
1138 | { | |
1139 | static unsigned long oops_timestamp; | |
1140 | ||
1141 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 1142 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
1143 | return; |
1144 | ||
1145 | oops_timestamp = jiffies; | |
1146 | ||
94d24fc4 | 1147 | debug_locks_off(); |
1da177e4 | 1148 | /* If a crash is occurring, make sure we can't deadlock */ |
07354eb1 | 1149 | raw_spin_lock_init(&logbuf_lock); |
1da177e4 | 1150 | /* And make sure that we print immediately */ |
5b8c4f23 | 1151 | sema_init(&console_sem, 1); |
1da177e4 LT |
1152 | } |
1153 | ||
76a8ad29 ME |
1154 | /* Check if we have any console registered that can be called early in boot. */ |
1155 | static int have_callable_console(void) | |
1156 | { | |
1157 | struct console *con; | |
1158 | ||
4d091611 | 1159 | for_each_console(con) |
76a8ad29 ME |
1160 | if (con->flags & CON_ANYTIME) |
1161 | return 1; | |
1162 | ||
1163 | return 0; | |
1164 | } | |
1165 | ||
266c2e0a LT |
1166 | /* |
1167 | * Can we actually use the console at this time on this cpu? | |
1168 | * | |
1169 | * Console drivers may assume that per-cpu resources have | |
1170 | * been allocated. So unless they're explicitly marked as | |
1171 | * being able to cope (CON_ANYTIME) don't call them until | |
1172 | * this CPU is officially up. | |
1173 | */ | |
1174 | static inline int can_use_console(unsigned int cpu) | |
1175 | { | |
1176 | return cpu_online(cpu) || have_callable_console(); | |
1177 | } | |
1178 | ||
1179 | /* | |
1180 | * Try to get console ownership to actually show the kernel | |
1181 | * messages from a 'printk'. Return true (and with the | |
ac751efa | 1182 | * console_lock held, and 'console_locked' set) if it |
266c2e0a LT |
1183 | * is successful, false otherwise. |
1184 | * | |
1185 | * This gets called with the 'logbuf_lock' spinlock held and | |
1186 | * interrupts disabled. It should return with 'lockbuf_lock' | |
1187 | * released but interrupts still disabled. | |
1188 | */ | |
ac751efa | 1189 | static int console_trylock_for_printk(unsigned int cpu) |
8155c02a | 1190 | __releases(&logbuf_lock) |
266c2e0a | 1191 | { |
0b5e1c52 | 1192 | int retval = 0, wake = 0; |
266c2e0a | 1193 | |
ac751efa | 1194 | if (console_trylock()) { |
093a07e2 LT |
1195 | retval = 1; |
1196 | ||
1197 | /* | |
1198 | * If we can't use the console, we need to release | |
1199 | * the console semaphore by hand to avoid flushing | |
1200 | * the buffer. We need to hold the console semaphore | |
1201 | * in order to do this test safely. | |
1202 | */ | |
1203 | if (!can_use_console(cpu)) { | |
1204 | console_locked = 0; | |
0b5e1c52 | 1205 | wake = 1; |
093a07e2 LT |
1206 | retval = 0; |
1207 | } | |
1208 | } | |
7ff9554b | 1209 | logbuf_cpu = UINT_MAX; |
0b5e1c52 PZ |
1210 | if (wake) |
1211 | up(&console_sem); | |
07354eb1 | 1212 | raw_spin_unlock(&logbuf_lock); |
266c2e0a LT |
1213 | return retval; |
1214 | } | |
32a76006 | 1215 | |
af91322e DY |
1216 | int printk_delay_msec __read_mostly; |
1217 | ||
1218 | static inline void printk_delay(void) | |
1219 | { | |
1220 | if (unlikely(printk_delay_msec)) { | |
1221 | int m = printk_delay_msec; | |
1222 | ||
1223 | while (m--) { | |
1224 | mdelay(1); | |
1225 | touch_nmi_watchdog(); | |
1226 | } | |
1227 | } | |
1228 | } | |
1229 | ||
7ff9554b KS |
1230 | asmlinkage int vprintk_emit(int facility, int level, |
1231 | const char *dict, size_t dictlen, | |
1232 | const char *fmt, va_list args) | |
1da177e4 | 1233 | { |
7ff9554b KS |
1234 | static int recursion_bug; |
1235 | static char buf[LOG_LINE_MAX]; | |
1236 | static size_t buflen; | |
1237 | static int buflevel; | |
1238 | static char textbuf[LOG_LINE_MAX]; | |
5c5d5ca5 | 1239 | static struct task_struct *cont; |
7ff9554b KS |
1240 | char *text = textbuf; |
1241 | size_t textlen; | |
ac60ad74 | 1242 | unsigned long flags; |
32a76006 | 1243 | int this_cpu; |
7ff9554b | 1244 | bool newline = false; |
5c5d5ca5 | 1245 | bool prefix = false; |
7ff9554b | 1246 | int printed_len = 0; |
1da177e4 | 1247 | |
bfe8df3d | 1248 | boot_delay_msec(); |
af91322e | 1249 | printk_delay(); |
bfe8df3d | 1250 | |
1da177e4 | 1251 | /* This stops the holder of console_sem just where we want him */ |
1a9a8aef | 1252 | local_irq_save(flags); |
32a76006 IM |
1253 | this_cpu = smp_processor_id(); |
1254 | ||
1255 | /* | |
1256 | * Ouch, printk recursed into itself! | |
1257 | */ | |
7ff9554b | 1258 | if (unlikely(logbuf_cpu == this_cpu)) { |
32a76006 IM |
1259 | /* |
1260 | * If a crash is occurring during printk() on this CPU, | |
1261 | * then try to get the crash message out but make sure | |
1262 | * we can't deadlock. Otherwise just return to avoid the | |
1263 | * recursion and return - but flag the recursion so that | |
1264 | * it can be printed at the next appropriate moment: | |
1265 | */ | |
94d24fc4 | 1266 | if (!oops_in_progress && !lockdep_recursing(current)) { |
3b8945e8 | 1267 | recursion_bug = 1; |
32a76006 IM |
1268 | goto out_restore_irqs; |
1269 | } | |
1270 | zap_locks(); | |
1271 | } | |
1272 | ||
a0f1ccfd | 1273 | lockdep_off(); |
07354eb1 | 1274 | raw_spin_lock(&logbuf_lock); |
7ff9554b | 1275 | logbuf_cpu = this_cpu; |
1da177e4 | 1276 | |
3b8945e8 | 1277 | if (recursion_bug) { |
7ff9554b KS |
1278 | static const char recursion_msg[] = |
1279 | "BUG: recent printk recursion!"; | |
1280 | ||
3b8945e8 | 1281 | recursion_bug = 0; |
7ff9554b KS |
1282 | printed_len += strlen(recursion_msg); |
1283 | /* emit KERN_CRIT message */ | |
1284 | log_store(0, 2, NULL, 0, recursion_msg, printed_len); | |
32a76006 | 1285 | } |
1da177e4 | 1286 | |
7ff9554b KS |
1287 | /* |
1288 | * The printf needs to come first; we need the syslog | |
1289 | * prefix which might be passed-in as a parameter. | |
1290 | */ | |
1291 | textlen = vscnprintf(text, sizeof(textbuf), fmt, args); | |
5fd29d6c | 1292 | |
7ff9554b KS |
1293 | /* mark and strip a trailing newline */ |
1294 | if (textlen && text[textlen-1] == '\n') { | |
1295 | textlen--; | |
1296 | newline = true; | |
1297 | } | |
9d90c8d9 | 1298 | |
7ff9554b KS |
1299 | /* strip syslog prefix and extract log level or flags */ |
1300 | if (text[0] == '<' && text[1] && text[2] == '>') { | |
1301 | switch (text[1]) { | |
1302 | case '0' ... '7': | |
1303 | if (level == -1) | |
1304 | level = text[1] - '0'; | |
7ff9554b | 1305 | case 'd': /* KERN_DEFAULT */ |
5c5d5ca5 KS |
1306 | prefix = true; |
1307 | case 'c': /* KERN_CONT */ | |
7ff9554b KS |
1308 | text += 3; |
1309 | textlen -= 3; | |
5fd29d6c LT |
1310 | } |
1311 | } | |
1312 | ||
5c5d5ca5 KS |
1313 | if (buflen && (prefix || dict || cont != current)) { |
1314 | /* flush existing buffer */ | |
7ff9554b KS |
1315 | log_store(facility, buflevel, NULL, 0, buf, buflen); |
1316 | printed_len += buflen; | |
1317 | buflen = 0; | |
1318 | } | |
9d90c8d9 | 1319 | |
7ff9554b KS |
1320 | if (buflen == 0) { |
1321 | /* remember level for first message in the buffer */ | |
1322 | if (level == -1) | |
1323 | buflevel = default_message_loglevel; | |
1324 | else | |
1325 | buflevel = level; | |
1326 | } | |
ac60ad74 | 1327 | |
7ff9554b KS |
1328 | if (buflen || !newline) { |
1329 | /* append to existing buffer, or buffer until next message */ | |
1330 | if (buflen + textlen > sizeof(buf)) | |
1331 | textlen = sizeof(buf) - buflen; | |
1332 | memcpy(buf + buflen, text, textlen); | |
1333 | buflen += textlen; | |
1334 | } | |
ac60ad74 | 1335 | |
7ff9554b KS |
1336 | if (newline) { |
1337 | /* end of line; flush buffer */ | |
1338 | if (buflen) { | |
1339 | log_store(facility, buflevel, | |
1340 | dict, dictlen, buf, buflen); | |
1341 | printed_len += buflen; | |
1342 | buflen = 0; | |
1343 | } else { | |
1344 | log_store(facility, buflevel, | |
1345 | dict, dictlen, text, textlen); | |
1346 | printed_len += textlen; | |
1347 | } | |
5c5d5ca5 KS |
1348 | cont = NULL; |
1349 | } else { | |
1350 | /* remember thread which filled the buffer */ | |
1351 | cont = current; | |
1da177e4 LT |
1352 | } |
1353 | ||
266c2e0a | 1354 | /* |
7ff9554b KS |
1355 | * Try to acquire and then immediately release the console semaphore. |
1356 | * The release will print out buffers and wake up /dev/kmsg and syslog() | |
1357 | * users. | |
266c2e0a | 1358 | * |
7ff9554b KS |
1359 | * The console_trylock_for_printk() function will release 'logbuf_lock' |
1360 | * regardless of whether it actually gets the console semaphore or not. | |
266c2e0a | 1361 | */ |
ac751efa TH |
1362 | if (console_trylock_for_printk(this_cpu)) |
1363 | console_unlock(); | |
76a8ad29 | 1364 | |
266c2e0a | 1365 | lockdep_on(); |
32a76006 | 1366 | out_restore_irqs: |
1a9a8aef | 1367 | local_irq_restore(flags); |
76a8ad29 | 1368 | |
1da177e4 LT |
1369 | return printed_len; |
1370 | } | |
7ff9554b KS |
1371 | EXPORT_SYMBOL(vprintk_emit); |
1372 | ||
1373 | asmlinkage int vprintk(const char *fmt, va_list args) | |
1374 | { | |
1375 | return vprintk_emit(0, -1, NULL, 0, fmt, args); | |
1376 | } | |
1da177e4 LT |
1377 | EXPORT_SYMBOL(vprintk); |
1378 | ||
7ff9554b KS |
1379 | asmlinkage int printk_emit(int facility, int level, |
1380 | const char *dict, size_t dictlen, | |
1381 | const char *fmt, ...) | |
1382 | { | |
1383 | va_list args; | |
1384 | int r; | |
1385 | ||
1386 | va_start(args, fmt); | |
1387 | r = vprintk_emit(facility, level, dict, dictlen, fmt, args); | |
1388 | va_end(args); | |
1389 | ||
1390 | return r; | |
1391 | } | |
1392 | EXPORT_SYMBOL(printk_emit); | |
1393 | ||
1394 | /** | |
1395 | * printk - print a kernel message | |
1396 | * @fmt: format string | |
1397 | * | |
1398 | * This is printk(). It can be called from any context. We want it to work. | |
1399 | * | |
1400 | * We try to grab the console_lock. If we succeed, it's easy - we log the | |
1401 | * output and call the console drivers. If we fail to get the semaphore, we | |
1402 | * place the output into the log buffer and return. The current holder of | |
1403 | * the console_sem will notice the new output in console_unlock(); and will | |
1404 | * send it to the consoles before releasing the lock. | |
1405 | * | |
1406 | * One effect of this deferred printing is that code which calls printk() and | |
1407 | * then changes console_loglevel may break. This is because console_loglevel | |
1408 | * is inspected when the actual printing occurs. | |
1409 | * | |
1410 | * See also: | |
1411 | * printf(3) | |
1412 | * | |
1413 | * See the vsnprintf() documentation for format string extensions over C99. | |
1414 | */ | |
1415 | asmlinkage int printk(const char *fmt, ...) | |
1416 | { | |
1417 | va_list args; | |
1418 | int r; | |
1419 | ||
1420 | #ifdef CONFIG_KGDB_KDB | |
1421 | if (unlikely(kdb_trap_printk)) { | |
1422 | va_start(args, fmt); | |
1423 | r = vkdb_printf(fmt, args); | |
1424 | va_end(args); | |
1425 | return r; | |
1426 | } | |
1427 | #endif | |
1428 | va_start(args, fmt); | |
1429 | r = vprintk_emit(0, -1, NULL, 0, fmt, args); | |
1430 | va_end(args); | |
1431 | ||
1432 | return r; | |
1433 | } | |
1434 | EXPORT_SYMBOL(printk); | |
7f3a781d | 1435 | |
d59745ce MM |
1436 | #else |
1437 | ||
7f3a781d KS |
1438 | #define LOG_LINE_MAX 0 |
1439 | static struct log *log_from_idx(u32 idx) { return NULL; } | |
1440 | static u32 log_next(u32 idx) { return 0; } | |
1441 | static char *log_text(const struct log *msg) { return NULL; } | |
1442 | static void call_console_drivers(int level, const char *text, size_t len) {} | |
d59745ce | 1443 | |
7f3a781d | 1444 | #endif /* CONFIG_PRINTK */ |
d59745ce | 1445 | |
f7511d5f ST |
1446 | static int __add_preferred_console(char *name, int idx, char *options, |
1447 | char *brl_options) | |
1448 | { | |
1449 | struct console_cmdline *c; | |
1450 | int i; | |
1451 | ||
1452 | /* | |
1453 | * See if this tty is not yet registered, and | |
1454 | * if we have a slot free. | |
1455 | */ | |
1456 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
1457 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
1458 | console_cmdline[i].index == idx) { | |
1459 | if (!brl_options) | |
1460 | selected_console = i; | |
1461 | return 0; | |
1462 | } | |
1463 | if (i == MAX_CMDLINECONSOLES) | |
1464 | return -E2BIG; | |
1465 | if (!brl_options) | |
1466 | selected_console = i; | |
1467 | c = &console_cmdline[i]; | |
1468 | strlcpy(c->name, name, sizeof(c->name)); | |
1469 | c->options = options; | |
1470 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
1471 | c->brl_options = brl_options; | |
1472 | #endif | |
1473 | c->index = idx; | |
1474 | return 0; | |
1475 | } | |
2ea1c539 JB |
1476 | /* |
1477 | * Set up a list of consoles. Called from init/main.c | |
1478 | */ | |
1479 | static int __init console_setup(char *str) | |
1480 | { | |
eaa944af | 1481 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 1482 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
1483 | int idx; |
1484 | ||
f7511d5f ST |
1485 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1486 | if (!memcmp(str, "brl,", 4)) { | |
1487 | brl_options = ""; | |
1488 | str += 4; | |
1489 | } else if (!memcmp(str, "brl=", 4)) { | |
1490 | brl_options = str + 4; | |
1491 | str = strchr(brl_options, ','); | |
1492 | if (!str) { | |
1493 | printk(KERN_ERR "need port name after brl=\n"); | |
1494 | return 1; | |
1495 | } | |
1496 | *(str++) = 0; | |
1497 | } | |
1498 | #endif | |
1499 | ||
2ea1c539 JB |
1500 | /* |
1501 | * Decode str into name, index, options. | |
1502 | */ | |
1503 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
1504 | strcpy(buf, "ttyS"); |
1505 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 1506 | } else { |
eaa944af | 1507 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 1508 | } |
eaa944af | 1509 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
1510 | if ((options = strchr(str, ',')) != NULL) |
1511 | *(options++) = 0; | |
1512 | #ifdef __sparc__ | |
1513 | if (!strcmp(str, "ttya")) | |
eaa944af | 1514 | strcpy(buf, "ttyS0"); |
2ea1c539 | 1515 | if (!strcmp(str, "ttyb")) |
eaa944af | 1516 | strcpy(buf, "ttyS1"); |
2ea1c539 | 1517 | #endif |
eaa944af | 1518 | for (s = buf; *s; s++) |
2ea1c539 JB |
1519 | if ((*s >= '0' && *s <= '9') || *s == ',') |
1520 | break; | |
1521 | idx = simple_strtoul(s, NULL, 10); | |
1522 | *s = 0; | |
1523 | ||
f7511d5f | 1524 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 1525 | console_set_on_cmdline = 1; |
2ea1c539 JB |
1526 | return 1; |
1527 | } | |
1528 | __setup("console=", console_setup); | |
1529 | ||
3c0547ba MM |
1530 | /** |
1531 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
1532 | * @name: device name |
1533 | * @idx: device index | |
1534 | * @options: options for this console | |
3c0547ba MM |
1535 | * |
1536 | * The last preferred console added will be used for kernel messages | |
1537 | * and stdin/out/err for init. Normally this is used by console_setup | |
1538 | * above to handle user-supplied console arguments; however it can also | |
1539 | * be used by arch-specific code either to override the user or more | |
1540 | * commonly to provide a default console (ie from PROM variables) when | |
1541 | * the user has not supplied one. | |
1542 | */ | |
fb445ee5 | 1543 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 1544 | { |
f7511d5f | 1545 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
1546 | } |
1547 | ||
b6b1d877 | 1548 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
1549 | { |
1550 | struct console_cmdline *c; | |
1551 | int i; | |
1552 | ||
1553 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
1554 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
1555 | console_cmdline[i].index == idx) { | |
1556 | c = &console_cmdline[i]; | |
f735295b | 1557 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
1558 | c->name[sizeof(c->name) - 1] = 0; |
1559 | c->options = options; | |
1560 | c->index = idx_new; | |
1561 | return i; | |
1562 | } | |
1563 | /* not found */ | |
1564 | return -1; | |
1565 | } | |
1566 | ||
2329abfa | 1567 | bool console_suspend_enabled = 1; |
8f4ce8c3 AS |
1568 | EXPORT_SYMBOL(console_suspend_enabled); |
1569 | ||
1570 | static int __init console_suspend_disable(char *str) | |
1571 | { | |
1572 | console_suspend_enabled = 0; | |
1573 | return 1; | |
1574 | } | |
1575 | __setup("no_console_suspend", console_suspend_disable); | |
134620f7 YZ |
1576 | module_param_named(console_suspend, console_suspend_enabled, |
1577 | bool, S_IRUGO | S_IWUSR); | |
1578 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" | |
1579 | " and hibernate operations"); | |
8f4ce8c3 | 1580 | |
557240b4 LT |
1581 | /** |
1582 | * suspend_console - suspend the console subsystem | |
1583 | * | |
1584 | * This disables printk() while we go into suspend states | |
1585 | */ | |
1586 | void suspend_console(void) | |
1587 | { | |
8f4ce8c3 AS |
1588 | if (!console_suspend_enabled) |
1589 | return; | |
0d63081d | 1590 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
ac751efa | 1591 | console_lock(); |
557240b4 | 1592 | console_suspended = 1; |
403f3075 | 1593 | up(&console_sem); |
557240b4 LT |
1594 | } |
1595 | ||
1596 | void resume_console(void) | |
1597 | { | |
8f4ce8c3 AS |
1598 | if (!console_suspend_enabled) |
1599 | return; | |
403f3075 | 1600 | down(&console_sem); |
557240b4 | 1601 | console_suspended = 0; |
ac751efa | 1602 | console_unlock(); |
557240b4 LT |
1603 | } |
1604 | ||
034260d6 KC |
1605 | /** |
1606 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
1607 | * @self: notifier struct | |
1608 | * @action: CPU hotplug event | |
1609 | * @hcpu: unused | |
1610 | * | |
1611 | * If printk() is called from a CPU that is not online yet, the messages | |
1612 | * will be spooled but will not show up on the console. This function is | |
1613 | * called when a new CPU comes online (or fails to come up), and ensures | |
1614 | * that any such output gets printed. | |
1615 | */ | |
1616 | static int __cpuinit console_cpu_notify(struct notifier_block *self, | |
1617 | unsigned long action, void *hcpu) | |
1618 | { | |
1619 | switch (action) { | |
1620 | case CPU_ONLINE: | |
1621 | case CPU_DEAD: | |
1622 | case CPU_DYING: | |
1623 | case CPU_DOWN_FAILED: | |
1624 | case CPU_UP_CANCELED: | |
ac751efa TH |
1625 | console_lock(); |
1626 | console_unlock(); | |
034260d6 KC |
1627 | } |
1628 | return NOTIFY_OK; | |
1629 | } | |
1630 | ||
1da177e4 | 1631 | /** |
ac751efa | 1632 | * console_lock - lock the console system for exclusive use. |
1da177e4 | 1633 | * |
ac751efa | 1634 | * Acquires a lock which guarantees that the caller has |
1da177e4 LT |
1635 | * exclusive access to the console system and the console_drivers list. |
1636 | * | |
1637 | * Can sleep, returns nothing. | |
1638 | */ | |
ac751efa | 1639 | void console_lock(void) |
1da177e4 | 1640 | { |
8abd8e29 | 1641 | BUG_ON(in_interrupt()); |
1da177e4 | 1642 | down(&console_sem); |
403f3075 AH |
1643 | if (console_suspended) |
1644 | return; | |
1da177e4 LT |
1645 | console_locked = 1; |
1646 | console_may_schedule = 1; | |
1647 | } | |
ac751efa | 1648 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 1649 | |
ac751efa TH |
1650 | /** |
1651 | * console_trylock - try to lock the console system for exclusive use. | |
1652 | * | |
1653 | * Tried to acquire a lock which guarantees that the caller has | |
1654 | * exclusive access to the console system and the console_drivers list. | |
1655 | * | |
1656 | * returns 1 on success, and 0 on failure to acquire the lock. | |
1657 | */ | |
1658 | int console_trylock(void) | |
1da177e4 LT |
1659 | { |
1660 | if (down_trylock(&console_sem)) | |
ac751efa | 1661 | return 0; |
403f3075 AH |
1662 | if (console_suspended) { |
1663 | up(&console_sem); | |
ac751efa | 1664 | return 0; |
403f3075 | 1665 | } |
1da177e4 LT |
1666 | console_locked = 1; |
1667 | console_may_schedule = 0; | |
ac751efa | 1668 | return 1; |
1da177e4 | 1669 | } |
ac751efa | 1670 | EXPORT_SYMBOL(console_trylock); |
1da177e4 LT |
1671 | |
1672 | int is_console_locked(void) | |
1673 | { | |
1674 | return console_locked; | |
1675 | } | |
1da177e4 | 1676 | |
3ccf3e83 | 1677 | /* |
7ff9554b | 1678 | * Delayed printk version, for scheduler-internal messages: |
3ccf3e83 PZ |
1679 | */ |
1680 | #define PRINTK_BUF_SIZE 512 | |
1681 | ||
1682 | #define PRINTK_PENDING_WAKEUP 0x01 | |
1683 | #define PRINTK_PENDING_SCHED 0x02 | |
1684 | ||
b845b517 | 1685 | static DEFINE_PER_CPU(int, printk_pending); |
3ccf3e83 | 1686 | static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf); |
b845b517 PZ |
1687 | |
1688 | void printk_tick(void) | |
e3e8a75d | 1689 | { |
40dc11ff | 1690 | if (__this_cpu_read(printk_pending)) { |
3ccf3e83 PZ |
1691 | int pending = __this_cpu_xchg(printk_pending, 0); |
1692 | if (pending & PRINTK_PENDING_SCHED) { | |
1693 | char *buf = __get_cpu_var(printk_sched_buf); | |
1694 | printk(KERN_WARNING "[sched_delayed] %s", buf); | |
1695 | } | |
1696 | if (pending & PRINTK_PENDING_WAKEUP) | |
1697 | wake_up_interruptible(&log_wait); | |
b845b517 PZ |
1698 | } |
1699 | } | |
1700 | ||
1701 | int printk_needs_cpu(int cpu) | |
1702 | { | |
40dc11ff | 1703 | if (cpu_is_offline(cpu)) |
61ab2544 | 1704 | printk_tick(); |
40dc11ff | 1705 | return __this_cpu_read(printk_pending); |
b845b517 PZ |
1706 | } |
1707 | ||
1708 | void wake_up_klogd(void) | |
1709 | { | |
1710 | if (waitqueue_active(&log_wait)) | |
3ccf3e83 | 1711 | this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); |
e3e8a75d KK |
1712 | } |
1713 | ||
7ff9554b KS |
1714 | /* the next printk record to write to the console */ |
1715 | static u64 console_seq; | |
1716 | static u32 console_idx; | |
1717 | ||
1da177e4 | 1718 | /** |
ac751efa | 1719 | * console_unlock - unlock the console system |
1da177e4 | 1720 | * |
ac751efa | 1721 | * Releases the console_lock which the caller holds on the console system |
1da177e4 LT |
1722 | * and the console driver list. |
1723 | * | |
ac751efa TH |
1724 | * While the console_lock was held, console output may have been buffered |
1725 | * by printk(). If this is the case, console_unlock(); emits | |
1726 | * the output prior to releasing the lock. | |
1da177e4 | 1727 | * |
7f3a781d | 1728 | * If there is output waiting, we wake /dev/kmsg and syslog() users. |
1da177e4 | 1729 | * |
ac751efa | 1730 | * console_unlock(); may be called from any context. |
1da177e4 | 1731 | */ |
ac751efa | 1732 | void console_unlock(void) |
1da177e4 | 1733 | { |
7ff9554b | 1734 | static u64 seen_seq; |
1da177e4 | 1735 | unsigned long flags; |
7ff9554b KS |
1736 | bool wake_klogd = false; |
1737 | bool retry; | |
1da177e4 | 1738 | |
557240b4 | 1739 | if (console_suspended) { |
403f3075 | 1740 | up(&console_sem); |
557240b4 LT |
1741 | return; |
1742 | } | |
78944e54 AD |
1743 | |
1744 | console_may_schedule = 0; | |
1745 | ||
4f2a8d3c | 1746 | again: |
7ff9554b KS |
1747 | for (;;) { |
1748 | struct log *msg; | |
1749 | static char text[LOG_LINE_MAX]; | |
649e6ee3 | 1750 | size_t len, l; |
7ff9554b KS |
1751 | int level; |
1752 | ||
07354eb1 | 1753 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
7ff9554b KS |
1754 | if (seen_seq != log_next_seq) { |
1755 | wake_klogd = true; | |
1756 | seen_seq = log_next_seq; | |
1757 | } | |
1758 | ||
1759 | if (console_seq < log_first_seq) { | |
1760 | /* messages are gone, move to first one */ | |
1761 | console_seq = log_first_seq; | |
1762 | console_idx = log_first_idx; | |
1763 | } | |
1764 | ||
1765 | if (console_seq == log_next_seq) | |
1766 | break; | |
1767 | ||
1768 | msg = log_from_idx(console_idx); | |
1769 | level = msg->level & 7; | |
649e6ee3 KS |
1770 | |
1771 | len = prepend_timestamp(msg->ts_nsec, text); | |
1772 | l = msg->text_len; | |
1773 | if (len + l + 1 >= sizeof(text)) | |
1774 | l = sizeof(text) - len - 1; | |
1775 | memcpy(text + len, log_text(msg), l); | |
1776 | len += l; | |
7ff9554b KS |
1777 | text[len++] = '\n'; |
1778 | ||
1779 | console_idx = log_next(console_idx); | |
1780 | console_seq++; | |
07354eb1 | 1781 | raw_spin_unlock(&logbuf_lock); |
7ff9554b | 1782 | |
81d68a96 | 1783 | stop_critical_timings(); /* don't trace print latency */ |
7ff9554b | 1784 | call_console_drivers(level, text, len); |
81d68a96 | 1785 | start_critical_timings(); |
1da177e4 LT |
1786 | local_irq_restore(flags); |
1787 | } | |
1788 | console_locked = 0; | |
fe3d8ad3 FT |
1789 | |
1790 | /* Release the exclusive_console once it is used */ | |
1791 | if (unlikely(exclusive_console)) | |
1792 | exclusive_console = NULL; | |
1793 | ||
07354eb1 | 1794 | raw_spin_unlock(&logbuf_lock); |
4f2a8d3c | 1795 | |
0b5e1c52 | 1796 | up(&console_sem); |
4f2a8d3c PZ |
1797 | |
1798 | /* | |
1799 | * Someone could have filled up the buffer again, so re-check if there's | |
1800 | * something to flush. In case we cannot trylock the console_sem again, | |
1801 | * there's a new owner and the console_unlock() from them will do the | |
1802 | * flush, no worries. | |
1803 | */ | |
07354eb1 | 1804 | raw_spin_lock(&logbuf_lock); |
7ff9554b | 1805 | retry = console_seq != log_next_seq; |
09dc3cf9 PZ |
1806 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
1807 | ||
4f2a8d3c PZ |
1808 | if (retry && console_trylock()) |
1809 | goto again; | |
1810 | ||
e3e8a75d KK |
1811 | if (wake_klogd) |
1812 | wake_up_klogd(); | |
1da177e4 | 1813 | } |
ac751efa | 1814 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 1815 | |
ddad86c2 MW |
1816 | /** |
1817 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1818 | * |
1819 | * If the console code is currently allowed to sleep, and | |
1820 | * if this CPU should yield the CPU to another task, do | |
1821 | * so here. | |
1822 | * | |
ac751efa | 1823 | * Must be called within console_lock();. |
1da177e4 LT |
1824 | */ |
1825 | void __sched console_conditional_schedule(void) | |
1826 | { | |
1827 | if (console_may_schedule) | |
1828 | cond_resched(); | |
1829 | } | |
1830 | EXPORT_SYMBOL(console_conditional_schedule); | |
1831 | ||
1da177e4 LT |
1832 | void console_unblank(void) |
1833 | { | |
1834 | struct console *c; | |
1835 | ||
1836 | /* | |
1837 | * console_unblank can no longer be called in interrupt context unless | |
1838 | * oops_in_progress is set to 1.. | |
1839 | */ | |
1840 | if (oops_in_progress) { | |
1841 | if (down_trylock(&console_sem) != 0) | |
1842 | return; | |
1843 | } else | |
ac751efa | 1844 | console_lock(); |
1da177e4 LT |
1845 | |
1846 | console_locked = 1; | |
1847 | console_may_schedule = 0; | |
4d091611 | 1848 | for_each_console(c) |
1da177e4 LT |
1849 | if ((c->flags & CON_ENABLED) && c->unblank) |
1850 | c->unblank(); | |
ac751efa | 1851 | console_unlock(); |
1da177e4 | 1852 | } |
1da177e4 LT |
1853 | |
1854 | /* | |
1855 | * Return the console tty driver structure and its associated index | |
1856 | */ | |
1857 | struct tty_driver *console_device(int *index) | |
1858 | { | |
1859 | struct console *c; | |
1860 | struct tty_driver *driver = NULL; | |
1861 | ||
ac751efa | 1862 | console_lock(); |
4d091611 | 1863 | for_each_console(c) { |
1da177e4 LT |
1864 | if (!c->device) |
1865 | continue; | |
1866 | driver = c->device(c, index); | |
1867 | if (driver) | |
1868 | break; | |
1869 | } | |
ac751efa | 1870 | console_unlock(); |
1da177e4 LT |
1871 | return driver; |
1872 | } | |
1873 | ||
1874 | /* | |
1875 | * Prevent further output on the passed console device so that (for example) | |
1876 | * serial drivers can disable console output before suspending a port, and can | |
1877 | * re-enable output afterwards. | |
1878 | */ | |
1879 | void console_stop(struct console *console) | |
1880 | { | |
ac751efa | 1881 | console_lock(); |
1da177e4 | 1882 | console->flags &= ~CON_ENABLED; |
ac751efa | 1883 | console_unlock(); |
1da177e4 LT |
1884 | } |
1885 | EXPORT_SYMBOL(console_stop); | |
1886 | ||
1887 | void console_start(struct console *console) | |
1888 | { | |
ac751efa | 1889 | console_lock(); |
1da177e4 | 1890 | console->flags |= CON_ENABLED; |
ac751efa | 1891 | console_unlock(); |
1da177e4 LT |
1892 | } |
1893 | EXPORT_SYMBOL(console_start); | |
1894 | ||
7bf69395 FDN |
1895 | static int __read_mostly keep_bootcon; |
1896 | ||
1897 | static int __init keep_bootcon_setup(char *str) | |
1898 | { | |
1899 | keep_bootcon = 1; | |
1900 | printk(KERN_INFO "debug: skip boot console de-registration.\n"); | |
1901 | ||
1902 | return 0; | |
1903 | } | |
1904 | ||
1905 | early_param("keep_bootcon", keep_bootcon_setup); | |
1906 | ||
1da177e4 LT |
1907 | /* |
1908 | * The console driver calls this routine during kernel initialization | |
1909 | * to register the console printing procedure with printk() and to | |
1910 | * print any messages that were printed by the kernel before the | |
1911 | * console driver was initialized. | |
4d091611 RG |
1912 | * |
1913 | * This can happen pretty early during the boot process (because of | |
1914 | * early_printk) - sometimes before setup_arch() completes - be careful | |
1915 | * of what kernel features are used - they may not be initialised yet. | |
1916 | * | |
1917 | * There are two types of consoles - bootconsoles (early_printk) and | |
1918 | * "real" consoles (everything which is not a bootconsole) which are | |
1919 | * handled differently. | |
1920 | * - Any number of bootconsoles can be registered at any time. | |
1921 | * - As soon as a "real" console is registered, all bootconsoles | |
1922 | * will be unregistered automatically. | |
1923 | * - Once a "real" console is registered, any attempt to register a | |
1924 | * bootconsoles will be rejected | |
1da177e4 | 1925 | */ |
4d091611 | 1926 | void register_console(struct console *newcon) |
1da177e4 | 1927 | { |
40dc5651 | 1928 | int i; |
1da177e4 | 1929 | unsigned long flags; |
4d091611 | 1930 | struct console *bcon = NULL; |
1da177e4 | 1931 | |
4d091611 RG |
1932 | /* |
1933 | * before we register a new CON_BOOT console, make sure we don't | |
1934 | * already have a valid console | |
1935 | */ | |
1936 | if (console_drivers && newcon->flags & CON_BOOT) { | |
1937 | /* find the last or real console */ | |
1938 | for_each_console(bcon) { | |
1939 | if (!(bcon->flags & CON_BOOT)) { | |
1940 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", | |
1941 | newcon->name, newcon->index); | |
1942 | return; | |
1943 | } | |
1944 | } | |
69331af7 GH |
1945 | } |
1946 | ||
4d091611 RG |
1947 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1948 | bcon = console_drivers; | |
1949 | ||
1950 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
1951 | preferred_console = selected_console; |
1952 | ||
4d091611 RG |
1953 | if (newcon->early_setup) |
1954 | newcon->early_setup(); | |
18a8bd94 | 1955 | |
1da177e4 LT |
1956 | /* |
1957 | * See if we want to use this console driver. If we | |
1958 | * didn't select a console we take the first one | |
1959 | * that registers here. | |
1960 | */ | |
1961 | if (preferred_console < 0) { | |
4d091611 RG |
1962 | if (newcon->index < 0) |
1963 | newcon->index = 0; | |
1964 | if (newcon->setup == NULL || | |
1965 | newcon->setup(newcon, NULL) == 0) { | |
1966 | newcon->flags |= CON_ENABLED; | |
1967 | if (newcon->device) { | |
1968 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
1969 | preferred_console = 0; |
1970 | } | |
1da177e4 LT |
1971 | } |
1972 | } | |
1973 | ||
1974 | /* | |
1975 | * See if this console matches one we selected on | |
1976 | * the command line. | |
1977 | */ | |
40dc5651 JJ |
1978 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1979 | i++) { | |
4d091611 | 1980 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1da177e4 | 1981 | continue; |
4d091611 RG |
1982 | if (newcon->index >= 0 && |
1983 | newcon->index != console_cmdline[i].index) | |
1da177e4 | 1984 | continue; |
4d091611 RG |
1985 | if (newcon->index < 0) |
1986 | newcon->index = console_cmdline[i].index; | |
f7511d5f ST |
1987 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1988 | if (console_cmdline[i].brl_options) { | |
4d091611 RG |
1989 | newcon->flags |= CON_BRL; |
1990 | braille_register_console(newcon, | |
f7511d5f ST |
1991 | console_cmdline[i].index, |
1992 | console_cmdline[i].options, | |
1993 | console_cmdline[i].brl_options); | |
1994 | return; | |
1995 | } | |
1996 | #endif | |
4d091611 RG |
1997 | if (newcon->setup && |
1998 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 1999 | break; |
4d091611 RG |
2000 | newcon->flags |= CON_ENABLED; |
2001 | newcon->index = console_cmdline[i].index; | |
ab4af03a | 2002 | if (i == selected_console) { |
4d091611 | 2003 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
2004 | preferred_console = selected_console; |
2005 | } | |
1da177e4 LT |
2006 | break; |
2007 | } | |
2008 | ||
4d091611 | 2009 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
2010 | return; |
2011 | ||
8259cf43 RG |
2012 | /* |
2013 | * If we have a bootconsole, and are switching to a real console, | |
2014 | * don't print everything out again, since when the boot console, and | |
2015 | * the real console are the same physical device, it's annoying to | |
2016 | * see the beginning boot messages twice | |
2017 | */ | |
2018 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 2019 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
2020 | |
2021 | /* | |
2022 | * Put this console in the list - keep the | |
2023 | * preferred driver at the head of the list. | |
2024 | */ | |
ac751efa | 2025 | console_lock(); |
4d091611 RG |
2026 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
2027 | newcon->next = console_drivers; | |
2028 | console_drivers = newcon; | |
2029 | if (newcon->next) | |
2030 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 2031 | } else { |
4d091611 RG |
2032 | newcon->next = console_drivers->next; |
2033 | console_drivers->next = newcon; | |
1da177e4 | 2034 | } |
4d091611 | 2035 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 | 2036 | /* |
ac751efa | 2037 | * console_unlock(); will print out the buffered messages |
1da177e4 LT |
2038 | * for us. |
2039 | */ | |
07354eb1 | 2040 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
7ff9554b KS |
2041 | console_seq = syslog_seq; |
2042 | console_idx = syslog_idx; | |
07354eb1 | 2043 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
fe3d8ad3 FT |
2044 | /* |
2045 | * We're about to replay the log buffer. Only do this to the | |
2046 | * just-registered console to avoid excessive message spam to | |
2047 | * the already-registered consoles. | |
2048 | */ | |
2049 | exclusive_console = newcon; | |
1da177e4 | 2050 | } |
ac751efa | 2051 | console_unlock(); |
fbc92a34 | 2052 | console_sysfs_notify(); |
8259cf43 RG |
2053 | |
2054 | /* | |
2055 | * By unregistering the bootconsoles after we enable the real console | |
2056 | * we get the "console xxx enabled" message on all the consoles - | |
2057 | * boot consoles, real consoles, etc - this is to ensure that end | |
2058 | * users know there might be something in the kernel's log buffer that | |
2059 | * went to the bootconsole (that they do not see on the real console) | |
2060 | */ | |
7bf69395 FDN |
2061 | if (bcon && |
2062 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && | |
2063 | !keep_bootcon) { | |
8259cf43 RG |
2064 | /* we need to iterate through twice, to make sure we print |
2065 | * everything out, before we unregister the console(s) | |
2066 | */ | |
2067 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", | |
2068 | newcon->name, newcon->index); | |
2069 | for_each_console(bcon) | |
2070 | if (bcon->flags & CON_BOOT) | |
2071 | unregister_console(bcon); | |
2072 | } else { | |
2073 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", | |
2074 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
2075 | newcon->name, newcon->index); | |
2076 | } | |
1da177e4 LT |
2077 | } |
2078 | EXPORT_SYMBOL(register_console); | |
2079 | ||
40dc5651 | 2080 | int unregister_console(struct console *console) |
1da177e4 | 2081 | { |
40dc5651 | 2082 | struct console *a, *b; |
1da177e4 LT |
2083 | int res = 1; |
2084 | ||
f7511d5f ST |
2085 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
2086 | if (console->flags & CON_BRL) | |
2087 | return braille_unregister_console(console); | |
2088 | #endif | |
2089 | ||
ac751efa | 2090 | console_lock(); |
1da177e4 LT |
2091 | if (console_drivers == console) { |
2092 | console_drivers=console->next; | |
2093 | res = 0; | |
e9b15b54 | 2094 | } else if (console_drivers) { |
1da177e4 LT |
2095 | for (a=console_drivers->next, b=console_drivers ; |
2096 | a; b=a, a=b->next) { | |
2097 | if (a == console) { | |
2098 | b->next = a->next; | |
2099 | res = 0; | |
2100 | break; | |
40dc5651 | 2101 | } |
1da177e4 LT |
2102 | } |
2103 | } | |
40dc5651 | 2104 | |
69331af7 | 2105 | /* |
ab4af03a GE |
2106 | * If this isn't the last console and it has CON_CONSDEV set, we |
2107 | * need to set it on the next preferred console. | |
1da177e4 | 2108 | */ |
69331af7 | 2109 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 2110 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 | 2111 | |
ac751efa | 2112 | console_unlock(); |
fbc92a34 | 2113 | console_sysfs_notify(); |
1da177e4 LT |
2114 | return res; |
2115 | } | |
2116 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 2117 | |
034260d6 | 2118 | static int __init printk_late_init(void) |
0c5564bd | 2119 | { |
4d091611 RG |
2120 | struct console *con; |
2121 | ||
2122 | for_each_console(con) { | |
4c30c6f5 | 2123 | if (!keep_bootcon && con->flags & CON_BOOT) { |
cb00e99c | 2124 | printk(KERN_INFO "turn off boot console %s%d\n", |
4d091611 | 2125 | con->name, con->index); |
42c2c8c8 | 2126 | unregister_console(con); |
cb00e99c | 2127 | } |
0c5564bd | 2128 | } |
034260d6 | 2129 | hotcpu_notifier(console_cpu_notify, 0); |
0c5564bd RG |
2130 | return 0; |
2131 | } | |
034260d6 | 2132 | late_initcall(printk_late_init); |
0c5564bd | 2133 | |
7ef3d2fd | 2134 | #if defined CONFIG_PRINTK |
717115e1 | 2135 | |
600e1458 PZ |
2136 | int printk_sched(const char *fmt, ...) |
2137 | { | |
2138 | unsigned long flags; | |
2139 | va_list args; | |
2140 | char *buf; | |
2141 | int r; | |
2142 | ||
2143 | local_irq_save(flags); | |
2144 | buf = __get_cpu_var(printk_sched_buf); | |
2145 | ||
2146 | va_start(args, fmt); | |
2147 | r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args); | |
2148 | va_end(args); | |
2149 | ||
2150 | __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED); | |
2151 | local_irq_restore(flags); | |
2152 | ||
2153 | return r; | |
2154 | } | |
2155 | ||
1da177e4 LT |
2156 | /* |
2157 | * printk rate limiting, lifted from the networking subsystem. | |
2158 | * | |
641de9d8 UKK |
2159 | * This enforces a rate limit: not more than 10 kernel messages |
2160 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 2161 | */ |
641de9d8 UKK |
2162 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
2163 | ||
5c828713 | 2164 | int __printk_ratelimit(const char *func) |
1da177e4 | 2165 | { |
5c828713 | 2166 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 2167 | } |
5c828713 | 2168 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
2169 | |
2170 | /** | |
2171 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
2172 | * @caller_jiffies: pointer to caller's state | |
2173 | * @interval_msecs: minimum interval between prints | |
2174 | * | |
2175 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
2176 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
2177 | * returned true. | |
2178 | */ | |
2179 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
2180 | unsigned int interval_msecs) | |
2181 | { | |
f2d28a2e GK |
2182 | if (*caller_jiffies == 0 |
2183 | || !time_in_range(jiffies, *caller_jiffies, | |
2184 | *caller_jiffies | |
2185 | + msecs_to_jiffies(interval_msecs))) { | |
2186 | *caller_jiffies = jiffies; | |
f46c4833 AM |
2187 | return true; |
2188 | } | |
2189 | return false; | |
2190 | } | |
2191 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
2192 | |
2193 | static DEFINE_SPINLOCK(dump_list_lock); | |
2194 | static LIST_HEAD(dump_list); | |
2195 | ||
2196 | /** | |
2197 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 2198 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
2199 | * |
2200 | * Adds a kernel log dumper to the system. The dump callback in the | |
2201 | * structure will be called when the kernel oopses or panics and must be | |
2202 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
2203 | */ | |
2204 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
2205 | { | |
2206 | unsigned long flags; | |
2207 | int err = -EBUSY; | |
2208 | ||
2209 | /* The dump callback needs to be set */ | |
2210 | if (!dumper->dump) | |
2211 | return -EINVAL; | |
2212 | ||
2213 | spin_lock_irqsave(&dump_list_lock, flags); | |
2214 | /* Don't allow registering multiple times */ | |
2215 | if (!dumper->registered) { | |
2216 | dumper->registered = 1; | |
fb842b00 | 2217 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
2218 | err = 0; |
2219 | } | |
2220 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
2221 | ||
2222 | return err; | |
2223 | } | |
2224 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
2225 | ||
2226 | /** | |
2227 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 2228 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
2229 | * |
2230 | * Removes a dump device from the system. Returns zero on success and | |
2231 | * %-EINVAL otherwise. | |
2232 | */ | |
2233 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
2234 | { | |
2235 | unsigned long flags; | |
2236 | int err = -EINVAL; | |
2237 | ||
2238 | spin_lock_irqsave(&dump_list_lock, flags); | |
2239 | if (dumper->registered) { | |
2240 | dumper->registered = 0; | |
fb842b00 | 2241 | list_del_rcu(&dumper->list); |
456b565c SK |
2242 | err = 0; |
2243 | } | |
2244 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 2245 | synchronize_rcu(); |
456b565c SK |
2246 | |
2247 | return err; | |
2248 | } | |
2249 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
2250 | ||
7ff9554b KS |
2251 | static bool always_kmsg_dump; |
2252 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); | |
2253 | ||
456b565c SK |
2254 | /** |
2255 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
2256 | * @reason: the reason (oops, panic etc) for dumping | |
2257 | * | |
2258 | * Iterate through each of the dump devices and call the oops/panic | |
2259 | * callbacks with the log buffer. | |
2260 | */ | |
2261 | void kmsg_dump(enum kmsg_dump_reason reason) | |
2262 | { | |
7ff9554b | 2263 | u64 idx; |
456b565c SK |
2264 | struct kmsg_dumper *dumper; |
2265 | const char *s1, *s2; | |
2266 | unsigned long l1, l2; | |
2267 | unsigned long flags; | |
2268 | ||
c22ab332 MG |
2269 | if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump) |
2270 | return; | |
2271 | ||
456b565c SK |
2272 | /* Theoretically, the log could move on after we do this, but |
2273 | there's not a lot we can do about that. The new messages | |
2274 | will overwrite the start of what we dump. */ | |
7ff9554b | 2275 | |
07354eb1 | 2276 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
7ff9554b KS |
2277 | if (syslog_seq < log_first_seq) |
2278 | idx = syslog_idx; | |
2279 | else | |
2280 | idx = log_first_idx; | |
456b565c | 2281 | |
7ff9554b KS |
2282 | if (idx > log_next_idx) { |
2283 | s1 = log_buf; | |
2284 | l1 = log_next_idx; | |
456b565c | 2285 | |
7ff9554b KS |
2286 | s2 = log_buf + idx; |
2287 | l2 = log_buf_len - idx; | |
456b565c SK |
2288 | } else { |
2289 | s1 = ""; | |
2290 | l1 = 0; | |
2291 | ||
7ff9554b KS |
2292 | s2 = log_buf + idx; |
2293 | l2 = log_next_idx - idx; | |
456b565c | 2294 | } |
7ff9554b | 2295 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
456b565c | 2296 | |
fb842b00 HY |
2297 | rcu_read_lock(); |
2298 | list_for_each_entry_rcu(dumper, &dump_list, list) | |
456b565c | 2299 | dumper->dump(dumper, reason, s1, l1, s2, l2); |
fb842b00 | 2300 | rcu_read_unlock(); |
456b565c | 2301 | } |
7ef3d2fd | 2302 | #endif |