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