Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/kernel/printk.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * Modified to make sys_syslog() more flexible: added commands to | |
7 | * return the last 4k of kernel messages, regardless of whether | |
8 | * they've been read or not. Added option to suppress kernel printk's | |
9 | * to the console. Added hook for sending the console messages | |
10 | * elsewhere, in preparation for a serial line console (someday). | |
11 | * Ted Ts'o, 2/11/93. | |
12 | * Modified for sysctl support, 1/8/97, Chris Horn. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 | 15 | * Rewrote bits to get rid of console_lock |
e1f8e874 | 16 | * 01Mar01 Andrew Morton |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
1da177e4 LT |
23 | #include <linux/console.h> |
24 | #include <linux/init.h> | |
bfe8df3d RD |
25 | #include <linux/jiffies.h> |
26 | #include <linux/nmi.h> | |
1da177e4 | 27 | #include <linux/module.h> |
3b9c0410 | 28 | #include <linux/moduleparam.h> |
1da177e4 | 29 | #include <linux/interrupt.h> /* For in_interrupt() */ |
1da177e4 LT |
30 | #include <linux/delay.h> |
31 | #include <linux/smp.h> | |
32 | #include <linux/security.h> | |
33 | #include <linux/bootmem.h> | |
162a7e75 | 34 | #include <linux/memblock.h> |
1da177e4 | 35 | #include <linux/syscalls.h> |
04d491ab | 36 | #include <linux/kexec.h> |
d37d39ae | 37 | #include <linux/kdb.h> |
3fff4c42 | 38 | #include <linux/ratelimit.h> |
456b565c | 39 | #include <linux/kmsg_dump.h> |
00234592 | 40 | #include <linux/syslog.h> |
034260d6 KC |
41 | #include <linux/cpu.h> |
42 | #include <linux/notifier.h> | |
fb842b00 | 43 | #include <linux/rculist.h> |
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 | ||
084681d1 | 196 | enum log_flags { |
5becfb1d KS |
197 | LOG_NOCONS = 1, /* already flushed, do not print to console */ |
198 | LOG_NEWLINE = 2, /* text ended with a newline */ | |
199 | LOG_PREFIX = 4, /* text started with a prefix */ | |
200 | LOG_CONT = 8, /* text is a fragment of a continuation line */ | |
084681d1 KS |
201 | }; |
202 | ||
7ff9554b KS |
203 | struct log { |
204 | u64 ts_nsec; /* timestamp in nanoseconds */ | |
205 | u16 len; /* length of entire record */ | |
206 | u16 text_len; /* length of text buffer */ | |
207 | u16 dict_len; /* length of dictionary buffer */ | |
084681d1 KS |
208 | u8 facility; /* syslog facility */ |
209 | u8 flags:5; /* internal record flags */ | |
210 | u8 level:3; /* syslog level */ | |
7ff9554b KS |
211 | }; |
212 | ||
213 | /* | |
214 | * The logbuf_lock protects kmsg buffer, indices, counters. It is also | |
215 | * used in interesting ways to provide interlocking in console_unlock(); | |
216 | */ | |
217 | static DEFINE_RAW_SPINLOCK(logbuf_lock); | |
d59745ce | 218 | |
96efedf1 | 219 | #ifdef CONFIG_PRINTK |
7f3a781d KS |
220 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
221 | static u64 syslog_seq; | |
222 | static u32 syslog_idx; | |
5becfb1d | 223 | static enum log_flags syslog_prev; |
eb02dac9 | 224 | static size_t syslog_partial; |
7ff9554b KS |
225 | |
226 | /* index and sequence number of the first record stored in the buffer */ | |
227 | static u64 log_first_seq; | |
228 | static u32 log_first_idx; | |
229 | ||
230 | /* index and sequence number of the next record to store in the buffer */ | |
231 | static u64 log_next_seq; | |
232 | static u32 log_next_idx; | |
233 | ||
eab07260 KS |
234 | /* the next printk record to write to the console */ |
235 | static u64 console_seq; | |
236 | static u32 console_idx; | |
237 | static enum log_flags console_prev; | |
238 | ||
7ff9554b KS |
239 | /* the next printk record to read after the last 'clear' command */ |
240 | static u64 clear_seq; | |
241 | static u32 clear_idx; | |
242 | ||
70498253 KS |
243 | #define PREFIX_MAX 32 |
244 | #define LOG_LINE_MAX 1024 - PREFIX_MAX | |
7f3a781d KS |
245 | |
246 | /* record buffer */ | |
6ebb017d | 247 | #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) |
f8450fca SW |
248 | #define LOG_ALIGN 4 |
249 | #else | |
6ebb017d | 250 | #define LOG_ALIGN __alignof__(struct log) |
f8450fca | 251 | #endif |
7f3a781d | 252 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
f8450fca | 253 | static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); |
7f3a781d KS |
254 | static char *log_buf = __log_buf; |
255 | static u32 log_buf_len = __LOG_BUF_LEN; | |
256 | ||
257 | /* cpu currently holding logbuf_lock */ | |
258 | static volatile unsigned int logbuf_cpu = UINT_MAX; | |
7ff9554b KS |
259 | |
260 | /* human readable text of the record */ | |
261 | static char *log_text(const struct log *msg) | |
262 | { | |
263 | return (char *)msg + sizeof(struct log); | |
264 | } | |
265 | ||
266 | /* optional key/value pair dictionary attached to the record */ | |
267 | static char *log_dict(const struct log *msg) | |
268 | { | |
269 | return (char *)msg + sizeof(struct log) + msg->text_len; | |
270 | } | |
271 | ||
272 | /* get record by index; idx must point to valid msg */ | |
273 | static struct log *log_from_idx(u32 idx) | |
274 | { | |
275 | struct log *msg = (struct log *)(log_buf + idx); | |
276 | ||
277 | /* | |
278 | * A length == 0 record is the end of buffer marker. Wrap around and | |
279 | * read the message at the start of the buffer. | |
280 | */ | |
281 | if (!msg->len) | |
282 | return (struct log *)log_buf; | |
283 | return msg; | |
284 | } | |
285 | ||
286 | /* get next record; idx must point to valid msg */ | |
287 | static u32 log_next(u32 idx) | |
288 | { | |
289 | struct log *msg = (struct log *)(log_buf + idx); | |
290 | ||
291 | /* length == 0 indicates the end of the buffer; wrap */ | |
292 | /* | |
293 | * A length == 0 record is the end of buffer marker. Wrap around and | |
294 | * read the message at the start of the buffer as *this* one, and | |
295 | * return the one after that. | |
296 | */ | |
297 | if (!msg->len) { | |
298 | msg = (struct log *)log_buf; | |
299 | return msg->len; | |
300 | } | |
301 | return idx + msg->len; | |
302 | } | |
303 | ||
7ff9554b KS |
304 | /* insert record into the buffer, discard old ones, update heads */ |
305 | static void log_store(int facility, int level, | |
084681d1 | 306 | enum log_flags flags, u64 ts_nsec, |
7ff9554b KS |
307 | const char *dict, u16 dict_len, |
308 | const char *text, u16 text_len) | |
309 | { | |
310 | struct log *msg; | |
311 | u32 size, pad_len; | |
312 | ||
313 | /* number of '\0' padding bytes to next message */ | |
314 | size = sizeof(struct log) + text_len + dict_len; | |
315 | pad_len = (-size) & (LOG_ALIGN - 1); | |
316 | size += pad_len; | |
317 | ||
318 | while (log_first_seq < log_next_seq) { | |
319 | u32 free; | |
320 | ||
321 | if (log_next_idx > log_first_idx) | |
322 | free = max(log_buf_len - log_next_idx, log_first_idx); | |
323 | else | |
324 | free = log_first_idx - log_next_idx; | |
325 | ||
326 | if (free > size + sizeof(struct log)) | |
327 | break; | |
328 | ||
329 | /* drop old messages until we have enough contiuous space */ | |
330 | log_first_idx = log_next(log_first_idx); | |
331 | log_first_seq++; | |
332 | } | |
333 | ||
334 | if (log_next_idx + size + sizeof(struct log) >= log_buf_len) { | |
335 | /* | |
336 | * This message + an additional empty header does not fit | |
337 | * at the end of the buffer. Add an empty header with len == 0 | |
338 | * to signify a wrap around. | |
339 | */ | |
340 | memset(log_buf + log_next_idx, 0, sizeof(struct log)); | |
341 | log_next_idx = 0; | |
342 | } | |
343 | ||
344 | /* fill message */ | |
345 | msg = (struct log *)(log_buf + log_next_idx); | |
346 | memcpy(log_text(msg), text, text_len); | |
347 | msg->text_len = text_len; | |
348 | memcpy(log_dict(msg), dict, dict_len); | |
349 | msg->dict_len = dict_len; | |
084681d1 KS |
350 | msg->facility = facility; |
351 | msg->level = level & 7; | |
352 | msg->flags = flags & 0x1f; | |
353 | if (ts_nsec > 0) | |
354 | msg->ts_nsec = ts_nsec; | |
355 | else | |
356 | msg->ts_nsec = local_clock(); | |
7ff9554b KS |
357 | memset(log_dict(msg) + dict_len, 0, pad_len); |
358 | msg->len = sizeof(struct log) + text_len + dict_len + pad_len; | |
359 | ||
360 | /* insert message */ | |
361 | log_next_idx += msg->len; | |
362 | log_next_seq++; | |
363 | } | |
d59745ce | 364 | |
e11fea92 KS |
365 | /* /dev/kmsg - userspace message inject/listen interface */ |
366 | struct devkmsg_user { | |
367 | u64 seq; | |
368 | u32 idx; | |
d39f3d77 | 369 | enum log_flags prev; |
e11fea92 KS |
370 | struct mutex lock; |
371 | char buf[8192]; | |
372 | }; | |
373 | ||
374 | static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv, | |
375 | unsigned long count, loff_t pos) | |
376 | { | |
377 | char *buf, *line; | |
378 | int i; | |
379 | int level = default_message_loglevel; | |
380 | int facility = 1; /* LOG_USER */ | |
381 | size_t len = iov_length(iv, count); | |
382 | ssize_t ret = len; | |
383 | ||
384 | if (len > LOG_LINE_MAX) | |
385 | return -EINVAL; | |
386 | buf = kmalloc(len+1, GFP_KERNEL); | |
387 | if (buf == NULL) | |
388 | return -ENOMEM; | |
389 | ||
390 | line = buf; | |
391 | for (i = 0; i < count; i++) { | |
392 | if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) | |
393 | goto out; | |
394 | line += iv[i].iov_len; | |
395 | } | |
396 | ||
397 | /* | |
398 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace | |
399 | * the decimal value represents 32bit, the lower 3 bit are the log | |
400 | * level, the rest are the log facility. | |
401 | * | |
402 | * If no prefix or no userspace facility is specified, we | |
403 | * enforce LOG_USER, to be able to reliably distinguish | |
404 | * kernel-generated messages from userspace-injected ones. | |
405 | */ | |
406 | line = buf; | |
407 | if (line[0] == '<') { | |
408 | char *endp = NULL; | |
409 | ||
410 | i = simple_strtoul(line+1, &endp, 10); | |
411 | if (endp && endp[0] == '>') { | |
412 | level = i & 7; | |
413 | if (i >> 3) | |
414 | facility = i >> 3; | |
415 | endp++; | |
416 | len -= endp - line; | |
417 | line = endp; | |
418 | } | |
419 | } | |
420 | line[len] = '\0'; | |
421 | ||
422 | printk_emit(facility, level, NULL, 0, "%s", line); | |
423 | out: | |
424 | kfree(buf); | |
425 | return ret; | |
426 | } | |
427 | ||
428 | static ssize_t devkmsg_read(struct file *file, char __user *buf, | |
429 | size_t count, loff_t *ppos) | |
430 | { | |
431 | struct devkmsg_user *user = file->private_data; | |
432 | struct log *msg; | |
5fc32490 | 433 | u64 ts_usec; |
e11fea92 | 434 | size_t i; |
d39f3d77 | 435 | char cont = '-'; |
e11fea92 KS |
436 | size_t len; |
437 | ssize_t ret; | |
438 | ||
439 | if (!user) | |
440 | return -EBADF; | |
441 | ||
4a77a5a0 YL |
442 | ret = mutex_lock_interruptible(&user->lock); |
443 | if (ret) | |
444 | return ret; | |
5c53d819 | 445 | raw_spin_lock_irq(&logbuf_lock); |
e11fea92 KS |
446 | while (user->seq == log_next_seq) { |
447 | if (file->f_flags & O_NONBLOCK) { | |
448 | ret = -EAGAIN; | |
5c53d819 | 449 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
450 | goto out; |
451 | } | |
452 | ||
5c53d819 | 453 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
454 | ret = wait_event_interruptible(log_wait, |
455 | user->seq != log_next_seq); | |
456 | if (ret) | |
457 | goto out; | |
5c53d819 | 458 | raw_spin_lock_irq(&logbuf_lock); |
e11fea92 KS |
459 | } |
460 | ||
461 | if (user->seq < log_first_seq) { | |
462 | /* our last seen message is gone, return error and reset */ | |
463 | user->idx = log_first_idx; | |
464 | user->seq = log_first_seq; | |
465 | ret = -EPIPE; | |
5c53d819 | 466 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
467 | goto out; |
468 | } | |
469 | ||
470 | msg = log_from_idx(user->idx); | |
5fc32490 KS |
471 | ts_usec = msg->ts_nsec; |
472 | do_div(ts_usec, 1000); | |
d39f3d77 KS |
473 | |
474 | /* | |
475 | * If we couldn't merge continuation line fragments during the print, | |
476 | * export the stored flags to allow an optional external merge of the | |
477 | * records. Merging the records isn't always neccessarily correct, like | |
478 | * when we hit a race during printing. In most cases though, it produces | |
479 | * better readable output. 'c' in the record flags mark the first | |
480 | * fragment of a line, '+' the following. | |
481 | */ | |
482 | if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT)) | |
483 | cont = 'c'; | |
484 | else if ((msg->flags & LOG_CONT) || | |
485 | ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))) | |
486 | cont = '+'; | |
487 | ||
488 | len = sprintf(user->buf, "%u,%llu,%llu,%c;", | |
489 | (msg->facility << 3) | msg->level, | |
490 | user->seq, ts_usec, cont); | |
491 | user->prev = msg->flags; | |
e11fea92 KS |
492 | |
493 | /* escape non-printable characters */ | |
494 | for (i = 0; i < msg->text_len; i++) { | |
3ce9a7c0 | 495 | unsigned char c = log_text(msg)[i]; |
e11fea92 | 496 | |
e3f5a5f2 | 497 | if (c < ' ' || c >= 127 || c == '\\') |
e11fea92 KS |
498 | len += sprintf(user->buf + len, "\\x%02x", c); |
499 | else | |
500 | user->buf[len++] = c; | |
501 | } | |
502 | user->buf[len++] = '\n'; | |
503 | ||
504 | if (msg->dict_len) { | |
505 | bool line = true; | |
506 | ||
507 | for (i = 0; i < msg->dict_len; i++) { | |
3ce9a7c0 | 508 | unsigned char c = log_dict(msg)[i]; |
e11fea92 KS |
509 | |
510 | if (line) { | |
511 | user->buf[len++] = ' '; | |
512 | line = false; | |
513 | } | |
514 | ||
515 | if (c == '\0') { | |
516 | user->buf[len++] = '\n'; | |
517 | line = true; | |
518 | continue; | |
519 | } | |
520 | ||
e3f5a5f2 | 521 | if (c < ' ' || c >= 127 || c == '\\') { |
e11fea92 KS |
522 | len += sprintf(user->buf + len, "\\x%02x", c); |
523 | continue; | |
524 | } | |
525 | ||
526 | user->buf[len++] = c; | |
527 | } | |
528 | user->buf[len++] = '\n'; | |
529 | } | |
530 | ||
531 | user->idx = log_next(user->idx); | |
532 | user->seq++; | |
5c53d819 | 533 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
534 | |
535 | if (len > count) { | |
536 | ret = -EINVAL; | |
537 | goto out; | |
538 | } | |
539 | ||
540 | if (copy_to_user(buf, user->buf, len)) { | |
541 | ret = -EFAULT; | |
542 | goto out; | |
543 | } | |
544 | ret = len; | |
545 | out: | |
546 | mutex_unlock(&user->lock); | |
547 | return ret; | |
548 | } | |
549 | ||
550 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) | |
551 | { | |
552 | struct devkmsg_user *user = file->private_data; | |
553 | loff_t ret = 0; | |
554 | ||
555 | if (!user) | |
556 | return -EBADF; | |
557 | if (offset) | |
558 | return -ESPIPE; | |
559 | ||
5c53d819 | 560 | raw_spin_lock_irq(&logbuf_lock); |
e11fea92 KS |
561 | switch (whence) { |
562 | case SEEK_SET: | |
563 | /* the first record */ | |
564 | user->idx = log_first_idx; | |
565 | user->seq = log_first_seq; | |
566 | break; | |
567 | case SEEK_DATA: | |
568 | /* | |
569 | * The first record after the last SYSLOG_ACTION_CLEAR, | |
570 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself | |
571 | * changes no global state, and does not clear anything. | |
572 | */ | |
573 | user->idx = clear_idx; | |
574 | user->seq = clear_seq; | |
575 | break; | |
576 | case SEEK_END: | |
577 | /* after the last record */ | |
578 | user->idx = log_next_idx; | |
579 | user->seq = log_next_seq; | |
580 | break; | |
581 | default: | |
582 | ret = -EINVAL; | |
583 | } | |
5c53d819 | 584 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
585 | return ret; |
586 | } | |
587 | ||
588 | static unsigned int devkmsg_poll(struct file *file, poll_table *wait) | |
589 | { | |
590 | struct devkmsg_user *user = file->private_data; | |
591 | int ret = 0; | |
592 | ||
593 | if (!user) | |
594 | return POLLERR|POLLNVAL; | |
595 | ||
596 | poll_wait(file, &log_wait, wait); | |
597 | ||
5c53d819 | 598 | raw_spin_lock_irq(&logbuf_lock); |
e11fea92 KS |
599 | if (user->seq < log_next_seq) { |
600 | /* return error when data has vanished underneath us */ | |
601 | if (user->seq < log_first_seq) | |
602 | ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI; | |
603 | ret = POLLIN|POLLRDNORM; | |
604 | } | |
5c53d819 | 605 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
606 | |
607 | return ret; | |
608 | } | |
609 | ||
610 | static int devkmsg_open(struct inode *inode, struct file *file) | |
611 | { | |
612 | struct devkmsg_user *user; | |
613 | int err; | |
614 | ||
615 | /* write-only does not need any file context */ | |
616 | if ((file->f_flags & O_ACCMODE) == O_WRONLY) | |
617 | return 0; | |
618 | ||
619 | err = security_syslog(SYSLOG_ACTION_READ_ALL); | |
620 | if (err) | |
621 | return err; | |
622 | ||
623 | user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); | |
624 | if (!user) | |
625 | return -ENOMEM; | |
626 | ||
627 | mutex_init(&user->lock); | |
628 | ||
5c53d819 | 629 | raw_spin_lock_irq(&logbuf_lock); |
e11fea92 KS |
630 | user->idx = log_first_idx; |
631 | user->seq = log_first_seq; | |
5c53d819 | 632 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
633 | |
634 | file->private_data = user; | |
635 | return 0; | |
636 | } | |
637 | ||
638 | static int devkmsg_release(struct inode *inode, struct file *file) | |
639 | { | |
640 | struct devkmsg_user *user = file->private_data; | |
641 | ||
642 | if (!user) | |
643 | return 0; | |
644 | ||
645 | mutex_destroy(&user->lock); | |
646 | kfree(user); | |
647 | return 0; | |
648 | } | |
649 | ||
650 | const struct file_operations kmsg_fops = { | |
651 | .open = devkmsg_open, | |
652 | .read = devkmsg_read, | |
653 | .aio_write = devkmsg_writev, | |
654 | .llseek = devkmsg_llseek, | |
655 | .poll = devkmsg_poll, | |
656 | .release = devkmsg_release, | |
657 | }; | |
658 | ||
04d491ab NH |
659 | #ifdef CONFIG_KEXEC |
660 | /* | |
661 | * This appends the listed symbols to /proc/vmcoreinfo | |
662 | * | |
663 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
664 | * obtain access to symbols that are otherwise very difficult to locate. These | |
665 | * symbols are specifically used so that utilities can access and extract the | |
666 | * dmesg log from a vmcore file after a crash. | |
667 | */ | |
668 | void log_buf_kexec_setup(void) | |
669 | { | |
670 | VMCOREINFO_SYMBOL(log_buf); | |
04d491ab | 671 | VMCOREINFO_SYMBOL(log_buf_len); |
7ff9554b KS |
672 | VMCOREINFO_SYMBOL(log_first_idx); |
673 | VMCOREINFO_SYMBOL(log_next_idx); | |
04d491ab NH |
674 | } |
675 | #endif | |
676 | ||
162a7e75 MT |
677 | /* requested log_buf_len from kernel cmdline */ |
678 | static unsigned long __initdata new_log_buf_len; | |
679 | ||
680 | /* save requested log_buf_len since it's too early to process it */ | |
1da177e4 LT |
681 | static int __init log_buf_len_setup(char *str) |
682 | { | |
eed4a2ab | 683 | unsigned size = memparse(str, &str); |
1da177e4 LT |
684 | |
685 | if (size) | |
686 | size = roundup_pow_of_two(size); | |
162a7e75 MT |
687 | if (size > log_buf_len) |
688 | new_log_buf_len = size; | |
689 | ||
690 | return 0; | |
1da177e4 | 691 | } |
162a7e75 MT |
692 | early_param("log_buf_len", log_buf_len_setup); |
693 | ||
694 | void __init setup_log_buf(int early) | |
695 | { | |
696 | unsigned long flags; | |
162a7e75 MT |
697 | char *new_log_buf; |
698 | int free; | |
699 | ||
700 | if (!new_log_buf_len) | |
701 | return; | |
1da177e4 | 702 | |
162a7e75 MT |
703 | if (early) { |
704 | unsigned long mem; | |
705 | ||
706 | mem = memblock_alloc(new_log_buf_len, PAGE_SIZE); | |
1f5026a7 | 707 | if (!mem) |
162a7e75 MT |
708 | return; |
709 | new_log_buf = __va(mem); | |
710 | } else { | |
711 | new_log_buf = alloc_bootmem_nopanic(new_log_buf_len); | |
712 | } | |
713 | ||
714 | if (unlikely(!new_log_buf)) { | |
715 | pr_err("log_buf_len: %ld bytes not available\n", | |
716 | new_log_buf_len); | |
717 | return; | |
718 | } | |
719 | ||
07354eb1 | 720 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
162a7e75 MT |
721 | log_buf_len = new_log_buf_len; |
722 | log_buf = new_log_buf; | |
723 | new_log_buf_len = 0; | |
7ff9554b KS |
724 | free = __LOG_BUF_LEN - log_next_idx; |
725 | memcpy(log_buf, __log_buf, __LOG_BUF_LEN); | |
07354eb1 | 726 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
162a7e75 MT |
727 | |
728 | pr_info("log_buf_len: %d\n", log_buf_len); | |
729 | pr_info("early log buf free: %d(%d%%)\n", | |
730 | free, (free * 100) / __LOG_BUF_LEN); | |
731 | } | |
1da177e4 | 732 | |
bfe8df3d RD |
733 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
734 | ||
674dff65 | 735 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 736 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
737 | |
738 | static int __init boot_delay_setup(char *str) | |
739 | { | |
740 | unsigned long lpj; | |
bfe8df3d RD |
741 | |
742 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
743 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
744 | ||
745 | get_option(&str, &boot_delay); | |
746 | if (boot_delay > 10 * 1000) | |
747 | boot_delay = 0; | |
748 | ||
3a3b6ed2 DY |
749 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
750 | "HZ: %d, loops_per_msec: %llu\n", | |
751 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
bfe8df3d RD |
752 | return 1; |
753 | } | |
754 | __setup("boot_delay=", boot_delay_setup); | |
755 | ||
756 | static void boot_delay_msec(void) | |
757 | { | |
758 | unsigned long long k; | |
759 | unsigned long timeout; | |
760 | ||
761 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
762 | return; | |
763 | ||
3a3b6ed2 | 764 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
765 | |
766 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
767 | while (k) { | |
768 | k--; | |
769 | cpu_relax(); | |
770 | /* | |
771 | * use (volatile) jiffies to prevent | |
772 | * compiler reduction; loop termination via jiffies | |
773 | * is secondary and may or may not happen. | |
774 | */ | |
775 | if (time_after(jiffies, timeout)) | |
776 | break; | |
777 | touch_nmi_watchdog(); | |
778 | } | |
779 | } | |
780 | #else | |
781 | static inline void boot_delay_msec(void) | |
782 | { | |
783 | } | |
784 | #endif | |
785 | ||
eaf06b24 DR |
786 | #ifdef CONFIG_SECURITY_DMESG_RESTRICT |
787 | int dmesg_restrict = 1; | |
788 | #else | |
789 | int dmesg_restrict; | |
790 | #endif | |
791 | ||
ee24aebf LT |
792 | static int syslog_action_restricted(int type) |
793 | { | |
794 | if (dmesg_restrict) | |
795 | return 1; | |
796 | /* Unless restricted, we allow "read all" and "get buffer size" for everybody */ | |
797 | return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; | |
798 | } | |
799 | ||
800 | static int check_syslog_permissions(int type, bool from_file) | |
801 | { | |
802 | /* | |
803 | * If this is from /proc/kmsg and we've already opened it, then we've | |
804 | * already done the capabilities checks at open time. | |
805 | */ | |
806 | if (from_file && type != SYSLOG_ACTION_OPEN) | |
807 | return 0; | |
808 | ||
809 | if (syslog_action_restricted(type)) { | |
810 | if (capable(CAP_SYSLOG)) | |
811 | return 0; | |
812 | /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */ | |
813 | if (capable(CAP_SYS_ADMIN)) { | |
f2c0d026 JN |
814 | printk_once(KERN_WARNING "%s (%d): " |
815 | "Attempt to access syslog with CAP_SYS_ADMIN " | |
816 | "but no CAP_SYSLOG (deprecated).\n", | |
817 | current->comm, task_pid_nr(current)); | |
ee24aebf LT |
818 | return 0; |
819 | } | |
820 | return -EPERM; | |
821 | } | |
822 | return 0; | |
823 | } | |
824 | ||
7ff9554b KS |
825 | #if defined(CONFIG_PRINTK_TIME) |
826 | static bool printk_time = 1; | |
827 | #else | |
828 | static bool printk_time; | |
829 | #endif | |
830 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); | |
831 | ||
084681d1 KS |
832 | static size_t print_time(u64 ts, char *buf) |
833 | { | |
834 | unsigned long rem_nsec; | |
835 | ||
836 | if (!printk_time) | |
837 | return 0; | |
838 | ||
839 | if (!buf) | |
840 | return 15; | |
841 | ||
842 | rem_nsec = do_div(ts, 1000000000); | |
843 | return sprintf(buf, "[%5lu.%06lu] ", | |
844 | (unsigned long)ts, rem_nsec / 1000); | |
845 | } | |
846 | ||
3ce9a7c0 | 847 | static size_t print_prefix(const struct log *msg, bool syslog, char *buf) |
649e6ee3 | 848 | { |
3ce9a7c0 | 849 | size_t len = 0; |
43a73a50 | 850 | unsigned int prefix = (msg->facility << 3) | msg->level; |
649e6ee3 | 851 | |
3ce9a7c0 KS |
852 | if (syslog) { |
853 | if (buf) { | |
43a73a50 | 854 | len += sprintf(buf, "<%u>", prefix); |
3ce9a7c0 KS |
855 | } else { |
856 | len += 3; | |
43a73a50 KS |
857 | if (prefix > 999) |
858 | len += 3; | |
859 | else if (prefix > 99) | |
860 | len += 2; | |
861 | else if (prefix > 9) | |
3ce9a7c0 KS |
862 | len++; |
863 | } | |
864 | } | |
649e6ee3 | 865 | |
084681d1 | 866 | len += print_time(msg->ts_nsec, buf ? buf + len : NULL); |
3ce9a7c0 | 867 | return len; |
649e6ee3 KS |
868 | } |
869 | ||
5becfb1d KS |
870 | static size_t msg_print_text(const struct log *msg, enum log_flags prev, |
871 | bool syslog, char *buf, size_t size) | |
7ff9554b | 872 | { |
3ce9a7c0 KS |
873 | const char *text = log_text(msg); |
874 | size_t text_size = msg->text_len; | |
5becfb1d KS |
875 | bool prefix = true; |
876 | bool newline = true; | |
3ce9a7c0 KS |
877 | size_t len = 0; |
878 | ||
5becfb1d KS |
879 | if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)) |
880 | prefix = false; | |
881 | ||
882 | if (msg->flags & LOG_CONT) { | |
883 | if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE)) | |
884 | prefix = false; | |
885 | ||
886 | if (!(msg->flags & LOG_NEWLINE)) | |
887 | newline = false; | |
888 | } | |
889 | ||
3ce9a7c0 KS |
890 | do { |
891 | const char *next = memchr(text, '\n', text_size); | |
892 | size_t text_len; | |
893 | ||
894 | if (next) { | |
895 | text_len = next - text; | |
896 | next++; | |
897 | text_size -= next - text; | |
898 | } else { | |
899 | text_len = text_size; | |
900 | } | |
7ff9554b | 901 | |
3ce9a7c0 KS |
902 | if (buf) { |
903 | if (print_prefix(msg, syslog, NULL) + | |
70498253 | 904 | text_len + 1 >= size - len) |
3ce9a7c0 | 905 | break; |
7ff9554b | 906 | |
5becfb1d KS |
907 | if (prefix) |
908 | len += print_prefix(msg, syslog, buf + len); | |
3ce9a7c0 KS |
909 | memcpy(buf + len, text, text_len); |
910 | len += text_len; | |
5becfb1d KS |
911 | if (next || newline) |
912 | buf[len++] = '\n'; | |
3ce9a7c0 KS |
913 | } else { |
914 | /* SYSLOG_ACTION_* buffer size only calculation */ | |
5becfb1d KS |
915 | if (prefix) |
916 | len += print_prefix(msg, syslog, NULL); | |
917 | len += text_len; | |
918 | if (next || newline) | |
919 | len++; | |
3ce9a7c0 | 920 | } |
7ff9554b | 921 | |
5becfb1d | 922 | prefix = true; |
3ce9a7c0 KS |
923 | text = next; |
924 | } while (text); | |
7ff9554b | 925 | |
7ff9554b KS |
926 | return len; |
927 | } | |
928 | ||
929 | static int syslog_print(char __user *buf, int size) | |
930 | { | |
931 | char *text; | |
3ce9a7c0 | 932 | struct log *msg; |
116e90b2 | 933 | int len = 0; |
7ff9554b | 934 | |
70498253 | 935 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
7ff9554b KS |
936 | if (!text) |
937 | return -ENOMEM; | |
938 | ||
116e90b2 JB |
939 | while (size > 0) { |
940 | size_t n; | |
eb02dac9 | 941 | size_t skip; |
116e90b2 JB |
942 | |
943 | raw_spin_lock_irq(&logbuf_lock); | |
944 | if (syslog_seq < log_first_seq) { | |
945 | /* messages are gone, move to first one */ | |
946 | syslog_seq = log_first_seq; | |
947 | syslog_idx = log_first_idx; | |
5becfb1d | 948 | syslog_prev = 0; |
eb02dac9 | 949 | syslog_partial = 0; |
116e90b2 JB |
950 | } |
951 | if (syslog_seq == log_next_seq) { | |
952 | raw_spin_unlock_irq(&logbuf_lock); | |
953 | break; | |
954 | } | |
eb02dac9 KS |
955 | |
956 | skip = syslog_partial; | |
116e90b2 | 957 | msg = log_from_idx(syslog_idx); |
70498253 KS |
958 | n = msg_print_text(msg, syslog_prev, true, text, |
959 | LOG_LINE_MAX + PREFIX_MAX); | |
eb02dac9 KS |
960 | if (n - syslog_partial <= size) { |
961 | /* message fits into buffer, move forward */ | |
116e90b2 JB |
962 | syslog_idx = log_next(syslog_idx); |
963 | syslog_seq++; | |
5becfb1d | 964 | syslog_prev = msg->flags; |
eb02dac9 KS |
965 | n -= syslog_partial; |
966 | syslog_partial = 0; | |
967 | } else if (!len){ | |
968 | /* partial read(), remember position */ | |
969 | n = size; | |
970 | syslog_partial += n; | |
116e90b2 JB |
971 | } else |
972 | n = 0; | |
973 | raw_spin_unlock_irq(&logbuf_lock); | |
974 | ||
975 | if (!n) | |
976 | break; | |
977 | ||
eb02dac9 | 978 | if (copy_to_user(buf, text + skip, n)) { |
116e90b2 JB |
979 | if (!len) |
980 | len = -EFAULT; | |
981 | break; | |
982 | } | |
eb02dac9 KS |
983 | |
984 | len += n; | |
985 | size -= n; | |
986 | buf += n; | |
7ff9554b | 987 | } |
7ff9554b KS |
988 | |
989 | kfree(text); | |
990 | return len; | |
991 | } | |
992 | ||
993 | static int syslog_print_all(char __user *buf, int size, bool clear) | |
994 | { | |
995 | char *text; | |
996 | int len = 0; | |
997 | ||
70498253 | 998 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
7ff9554b KS |
999 | if (!text) |
1000 | return -ENOMEM; | |
1001 | ||
1002 | raw_spin_lock_irq(&logbuf_lock); | |
1003 | if (buf) { | |
1004 | u64 next_seq; | |
1005 | u64 seq; | |
1006 | u32 idx; | |
5becfb1d | 1007 | enum log_flags prev; |
7ff9554b KS |
1008 | |
1009 | if (clear_seq < log_first_seq) { | |
1010 | /* messages are gone, move to first available one */ | |
1011 | clear_seq = log_first_seq; | |
1012 | clear_idx = log_first_idx; | |
1013 | } | |
1014 | ||
1015 | /* | |
1016 | * Find first record that fits, including all following records, | |
1017 | * into the user-provided buffer for this dump. | |
e2ae715d | 1018 | */ |
7ff9554b KS |
1019 | seq = clear_seq; |
1020 | idx = clear_idx; | |
5becfb1d | 1021 | prev = 0; |
7ff9554b | 1022 | while (seq < log_next_seq) { |
3ce9a7c0 KS |
1023 | struct log *msg = log_from_idx(idx); |
1024 | ||
5becfb1d | 1025 | len += msg_print_text(msg, prev, true, NULL, 0); |
7ff9554b KS |
1026 | idx = log_next(idx); |
1027 | seq++; | |
1028 | } | |
e2ae715d KS |
1029 | |
1030 | /* move first record forward until length fits into the buffer */ | |
7ff9554b KS |
1031 | seq = clear_seq; |
1032 | idx = clear_idx; | |
5becfb1d | 1033 | prev = 0; |
7ff9554b | 1034 | while (len > size && seq < log_next_seq) { |
3ce9a7c0 KS |
1035 | struct log *msg = log_from_idx(idx); |
1036 | ||
5becfb1d | 1037 | len -= msg_print_text(msg, prev, true, NULL, 0); |
7ff9554b KS |
1038 | idx = log_next(idx); |
1039 | seq++; | |
1040 | } | |
1041 | ||
e2ae715d | 1042 | /* last message fitting into this dump */ |
7ff9554b KS |
1043 | next_seq = log_next_seq; |
1044 | ||
1045 | len = 0; | |
5becfb1d | 1046 | prev = 0; |
7ff9554b | 1047 | while (len >= 0 && seq < next_seq) { |
3ce9a7c0 | 1048 | struct log *msg = log_from_idx(idx); |
7ff9554b KS |
1049 | int textlen; |
1050 | ||
70498253 KS |
1051 | textlen = msg_print_text(msg, prev, true, text, |
1052 | LOG_LINE_MAX + PREFIX_MAX); | |
7ff9554b KS |
1053 | if (textlen < 0) { |
1054 | len = textlen; | |
1055 | break; | |
1056 | } | |
1057 | idx = log_next(idx); | |
1058 | seq++; | |
5becfb1d | 1059 | prev = msg->flags; |
7ff9554b KS |
1060 | |
1061 | raw_spin_unlock_irq(&logbuf_lock); | |
1062 | if (copy_to_user(buf + len, text, textlen)) | |
1063 | len = -EFAULT; | |
1064 | else | |
1065 | len += textlen; | |
1066 | raw_spin_lock_irq(&logbuf_lock); | |
1067 | ||
1068 | if (seq < log_first_seq) { | |
1069 | /* messages are gone, move to next one */ | |
1070 | seq = log_first_seq; | |
1071 | idx = log_first_idx; | |
5becfb1d | 1072 | prev = 0; |
7ff9554b KS |
1073 | } |
1074 | } | |
1075 | } | |
1076 | ||
1077 | if (clear) { | |
1078 | clear_seq = log_next_seq; | |
1079 | clear_idx = log_next_idx; | |
1080 | } | |
1081 | raw_spin_unlock_irq(&logbuf_lock); | |
1082 | ||
1083 | kfree(text); | |
1084 | return len; | |
1085 | } | |
1086 | ||
00234592 | 1087 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
1da177e4 | 1088 | { |
7ff9554b KS |
1089 | bool clear = false; |
1090 | static int saved_console_loglevel = -1; | |
ee24aebf | 1091 | int error; |
1da177e4 | 1092 | |
ee24aebf LT |
1093 | error = check_syslog_permissions(type, from_file); |
1094 | if (error) | |
1095 | goto out; | |
12b3052c EP |
1096 | |
1097 | error = security_syslog(type); | |
1da177e4 LT |
1098 | if (error) |
1099 | return error; | |
1100 | ||
1101 | switch (type) { | |
d78ca3cd | 1102 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 1103 | break; |
d78ca3cd | 1104 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 1105 | break; |
d78ca3cd | 1106 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 LT |
1107 | error = -EINVAL; |
1108 | if (!buf || len < 0) | |
1109 | goto out; | |
1110 | error = 0; | |
1111 | if (!len) | |
1112 | goto out; | |
1113 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
1114 | error = -EFAULT; | |
1115 | goto out; | |
1116 | } | |
40dc5651 | 1117 | error = wait_event_interruptible(log_wait, |
7ff9554b | 1118 | syslog_seq != log_next_seq); |
cb424ffe | 1119 | if (error) |
1da177e4 | 1120 | goto out; |
7ff9554b | 1121 | error = syslog_print(buf, len); |
1da177e4 | 1122 | break; |
d78ca3cd KC |
1123 | /* Read/clear last kernel messages */ |
1124 | case SYSLOG_ACTION_READ_CLEAR: | |
7ff9554b | 1125 | clear = true; |
1da177e4 | 1126 | /* FALL THRU */ |
d78ca3cd KC |
1127 | /* Read last kernel messages */ |
1128 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 LT |
1129 | error = -EINVAL; |
1130 | if (!buf || len < 0) | |
1131 | goto out; | |
1132 | error = 0; | |
1133 | if (!len) | |
1134 | goto out; | |
1135 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
1136 | error = -EFAULT; | |
1137 | goto out; | |
1138 | } | |
7ff9554b | 1139 | error = syslog_print_all(buf, len, clear); |
1da177e4 | 1140 | break; |
d78ca3cd KC |
1141 | /* Clear ring buffer */ |
1142 | case SYSLOG_ACTION_CLEAR: | |
7ff9554b | 1143 | syslog_print_all(NULL, 0, true); |
4661e356 | 1144 | break; |
d78ca3cd KC |
1145 | /* Disable logging to console */ |
1146 | case SYSLOG_ACTION_CONSOLE_OFF: | |
1aaad49e FP |
1147 | if (saved_console_loglevel == -1) |
1148 | saved_console_loglevel = console_loglevel; | |
1da177e4 LT |
1149 | console_loglevel = minimum_console_loglevel; |
1150 | break; | |
d78ca3cd KC |
1151 | /* Enable logging to console */ |
1152 | case SYSLOG_ACTION_CONSOLE_ON: | |
1aaad49e FP |
1153 | if (saved_console_loglevel != -1) { |
1154 | console_loglevel = saved_console_loglevel; | |
1155 | saved_console_loglevel = -1; | |
1156 | } | |
1da177e4 | 1157 | break; |
d78ca3cd KC |
1158 | /* Set level of messages printed to console */ |
1159 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 LT |
1160 | error = -EINVAL; |
1161 | if (len < 1 || len > 8) | |
1162 | goto out; | |
1163 | if (len < minimum_console_loglevel) | |
1164 | len = minimum_console_loglevel; | |
1165 | console_loglevel = len; | |
1aaad49e FP |
1166 | /* Implicitly re-enable logging to console */ |
1167 | saved_console_loglevel = -1; | |
1da177e4 LT |
1168 | error = 0; |
1169 | break; | |
d78ca3cd KC |
1170 | /* Number of chars in the log buffer */ |
1171 | case SYSLOG_ACTION_SIZE_UNREAD: | |
7ff9554b KS |
1172 | raw_spin_lock_irq(&logbuf_lock); |
1173 | if (syslog_seq < log_first_seq) { | |
1174 | /* messages are gone, move to first one */ | |
1175 | syslog_seq = log_first_seq; | |
1176 | syslog_idx = log_first_idx; | |
5becfb1d | 1177 | syslog_prev = 0; |
eb02dac9 | 1178 | syslog_partial = 0; |
7ff9554b KS |
1179 | } |
1180 | if (from_file) { | |
1181 | /* | |
1182 | * Short-cut for poll(/"proc/kmsg") which simply checks | |
1183 | * for pending data, not the size; return the count of | |
1184 | * records, not the length. | |
1185 | */ | |
1186 | error = log_next_idx - syslog_idx; | |
1187 | } else { | |
5becfb1d KS |
1188 | u64 seq = syslog_seq; |
1189 | u32 idx = syslog_idx; | |
1190 | enum log_flags prev = syslog_prev; | |
7ff9554b KS |
1191 | |
1192 | error = 0; | |
7ff9554b | 1193 | while (seq < log_next_seq) { |
3ce9a7c0 KS |
1194 | struct log *msg = log_from_idx(idx); |
1195 | ||
5becfb1d | 1196 | error += msg_print_text(msg, prev, true, NULL, 0); |
7ff9554b KS |
1197 | idx = log_next(idx); |
1198 | seq++; | |
5becfb1d | 1199 | prev = msg->flags; |
7ff9554b | 1200 | } |
eb02dac9 | 1201 | error -= syslog_partial; |
7ff9554b KS |
1202 | } |
1203 | raw_spin_unlock_irq(&logbuf_lock); | |
1da177e4 | 1204 | break; |
d78ca3cd KC |
1205 | /* Size of the log buffer */ |
1206 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
1207 | error = log_buf_len; |
1208 | break; | |
1209 | default: | |
1210 | error = -EINVAL; | |
1211 | break; | |
1212 | } | |
1213 | out: | |
1214 | return error; | |
1215 | } | |
1216 | ||
1e7bfb21 | 1217 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 1218 | { |
00234592 | 1219 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
1da177e4 LT |
1220 | } |
1221 | ||
67fc4e0c JW |
1222 | #ifdef CONFIG_KGDB_KDB |
1223 | /* kdb dmesg command needs access to the syslog buffer. do_syslog() | |
1224 | * uses locks so it cannot be used during debugging. Just tell kdb | |
1225 | * where the start and end of the physical and logical logs are. This | |
1226 | * is equivalent to do_syslog(3). | |
1227 | */ | |
1228 | void kdb_syslog_data(char *syslog_data[4]) | |
1229 | { | |
1230 | syslog_data[0] = log_buf; | |
1231 | syslog_data[1] = log_buf + log_buf_len; | |
7ff9554b KS |
1232 | syslog_data[2] = log_buf + log_first_idx; |
1233 | syslog_data[3] = log_buf + log_next_idx; | |
67fc4e0c JW |
1234 | } |
1235 | #endif /* CONFIG_KGDB_KDB */ | |
1236 | ||
2329abfa | 1237 | static bool __read_mostly ignore_loglevel; |
79290822 | 1238 | |
99eea6a1 | 1239 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
1240 | { |
1241 | ignore_loglevel = 1; | |
1242 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
1243 | ||
c4772d99 | 1244 | return 0; |
79290822 IM |
1245 | } |
1246 | ||
c4772d99 | 1247 | early_param("ignore_loglevel", ignore_loglevel_setup); |
29d4d6df | 1248 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); |
0eca6b7c YZ |
1249 | MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to" |
1250 | "print all kernel messages to the console."); | |
79290822 | 1251 | |
1da177e4 LT |
1252 | /* |
1253 | * Call the console drivers, asking them to write out | |
1254 | * log_buf[start] to log_buf[end - 1]. | |
ac751efa | 1255 | * The console_lock must be held. |
1da177e4 | 1256 | */ |
7ff9554b | 1257 | static void call_console_drivers(int level, const char *text, size_t len) |
1da177e4 | 1258 | { |
7ff9554b | 1259 | struct console *con; |
1da177e4 | 1260 | |
7ff9554b KS |
1261 | trace_console(text, 0, len, len); |
1262 | ||
1263 | if (level >= console_loglevel && !ignore_loglevel) | |
1264 | return; | |
1265 | if (!console_drivers) | |
1266 | return; | |
1267 | ||
1268 | for_each_console(con) { | |
1269 | if (exclusive_console && con != exclusive_console) | |
1270 | continue; | |
1271 | if (!(con->flags & CON_ENABLED)) | |
1272 | continue; | |
1273 | if (!con->write) | |
1274 | continue; | |
1275 | if (!cpu_online(smp_processor_id()) && | |
1276 | !(con->flags & CON_ANYTIME)) | |
1277 | continue; | |
1278 | con->write(con, text, len); | |
1279 | } | |
1da177e4 LT |
1280 | } |
1281 | ||
1282 | /* | |
1283 | * Zap console related locks when oopsing. Only zap at most once | |
1284 | * every 10 seconds, to leave time for slow consoles to print a | |
1285 | * full oops. | |
1286 | */ | |
1287 | static void zap_locks(void) | |
1288 | { | |
1289 | static unsigned long oops_timestamp; | |
1290 | ||
1291 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 1292 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
1293 | return; |
1294 | ||
1295 | oops_timestamp = jiffies; | |
1296 | ||
94d24fc4 | 1297 | debug_locks_off(); |
1da177e4 | 1298 | /* If a crash is occurring, make sure we can't deadlock */ |
07354eb1 | 1299 | raw_spin_lock_init(&logbuf_lock); |
1da177e4 | 1300 | /* And make sure that we print immediately */ |
5b8c4f23 | 1301 | sema_init(&console_sem, 1); |
1da177e4 LT |
1302 | } |
1303 | ||
76a8ad29 ME |
1304 | /* Check if we have any console registered that can be called early in boot. */ |
1305 | static int have_callable_console(void) | |
1306 | { | |
1307 | struct console *con; | |
1308 | ||
4d091611 | 1309 | for_each_console(con) |
76a8ad29 ME |
1310 | if (con->flags & CON_ANYTIME) |
1311 | return 1; | |
1312 | ||
1313 | return 0; | |
1314 | } | |
1315 | ||
266c2e0a LT |
1316 | /* |
1317 | * Can we actually use the console at this time on this cpu? | |
1318 | * | |
1319 | * Console drivers may assume that per-cpu resources have | |
1320 | * been allocated. So unless they're explicitly marked as | |
1321 | * being able to cope (CON_ANYTIME) don't call them until | |
1322 | * this CPU is officially up. | |
1323 | */ | |
1324 | static inline int can_use_console(unsigned int cpu) | |
1325 | { | |
1326 | return cpu_online(cpu) || have_callable_console(); | |
1327 | } | |
1328 | ||
1329 | /* | |
1330 | * Try to get console ownership to actually show the kernel | |
1331 | * messages from a 'printk'. Return true (and with the | |
ac751efa | 1332 | * console_lock held, and 'console_locked' set) if it |
266c2e0a LT |
1333 | * is successful, false otherwise. |
1334 | * | |
1335 | * This gets called with the 'logbuf_lock' spinlock held and | |
1336 | * interrupts disabled. It should return with 'lockbuf_lock' | |
1337 | * released but interrupts still disabled. | |
1338 | */ | |
ac751efa | 1339 | static int console_trylock_for_printk(unsigned int cpu) |
8155c02a | 1340 | __releases(&logbuf_lock) |
266c2e0a | 1341 | { |
0b5e1c52 | 1342 | int retval = 0, wake = 0; |
266c2e0a | 1343 | |
ac751efa | 1344 | if (console_trylock()) { |
093a07e2 LT |
1345 | retval = 1; |
1346 | ||
1347 | /* | |
1348 | * If we can't use the console, we need to release | |
1349 | * the console semaphore by hand to avoid flushing | |
1350 | * the buffer. We need to hold the console semaphore | |
1351 | * in order to do this test safely. | |
1352 | */ | |
1353 | if (!can_use_console(cpu)) { | |
1354 | console_locked = 0; | |
0b5e1c52 | 1355 | wake = 1; |
093a07e2 LT |
1356 | retval = 0; |
1357 | } | |
1358 | } | |
7ff9554b | 1359 | logbuf_cpu = UINT_MAX; |
0b5e1c52 PZ |
1360 | if (wake) |
1361 | up(&console_sem); | |
07354eb1 | 1362 | raw_spin_unlock(&logbuf_lock); |
266c2e0a LT |
1363 | return retval; |
1364 | } | |
32a76006 | 1365 | |
af91322e DY |
1366 | int printk_delay_msec __read_mostly; |
1367 | ||
1368 | static inline void printk_delay(void) | |
1369 | { | |
1370 | if (unlikely(printk_delay_msec)) { | |
1371 | int m = printk_delay_msec; | |
1372 | ||
1373 | while (m--) { | |
1374 | mdelay(1); | |
1375 | touch_nmi_watchdog(); | |
1376 | } | |
1377 | } | |
1378 | } | |
1379 | ||
084681d1 KS |
1380 | /* |
1381 | * Continuation lines are buffered, and not committed to the record buffer | |
1382 | * until the line is complete, or a race forces it. The line fragments | |
1383 | * though, are printed immediately to the consoles to ensure everything has | |
1384 | * reached the console in case of a kernel crash. | |
1385 | */ | |
1386 | static struct cont { | |
1387 | char buf[LOG_LINE_MAX]; | |
1388 | size_t len; /* length == 0 means unused buffer */ | |
1389 | size_t cons; /* bytes written to console */ | |
1390 | struct task_struct *owner; /* task of first print*/ | |
1391 | u64 ts_nsec; /* time of first print */ | |
1392 | u8 level; /* log level of first message */ | |
1393 | u8 facility; /* log level of first message */ | |
eab07260 | 1394 | enum log_flags flags; /* prefix, newline flags */ |
084681d1 KS |
1395 | bool flushed:1; /* buffer sealed and committed */ |
1396 | } cont; | |
1397 | ||
70498253 | 1398 | static void cont_flush(enum log_flags flags) |
084681d1 KS |
1399 | { |
1400 | if (cont.flushed) | |
1401 | return; | |
1402 | if (cont.len == 0) | |
1403 | return; | |
1404 | ||
eab07260 KS |
1405 | if (cont.cons) { |
1406 | /* | |
1407 | * If a fragment of this line was directly flushed to the | |
1408 | * console; wait for the console to pick up the rest of the | |
1409 | * line. LOG_NOCONS suppresses a duplicated output. | |
1410 | */ | |
1411 | log_store(cont.facility, cont.level, flags | LOG_NOCONS, | |
1412 | cont.ts_nsec, NULL, 0, cont.buf, cont.len); | |
1413 | cont.flags = flags; | |
1414 | cont.flushed = true; | |
1415 | } else { | |
1416 | /* | |
1417 | * If no fragment of this line ever reached the console, | |
1418 | * just submit it to the store and free the buffer. | |
1419 | */ | |
1420 | log_store(cont.facility, cont.level, flags, 0, | |
1421 | NULL, 0, cont.buf, cont.len); | |
1422 | cont.len = 0; | |
1423 | } | |
084681d1 KS |
1424 | } |
1425 | ||
1426 | static bool cont_add(int facility, int level, const char *text, size_t len) | |
1427 | { | |
1428 | if (cont.len && cont.flushed) | |
1429 | return false; | |
1430 | ||
1431 | if (cont.len + len > sizeof(cont.buf)) { | |
70498253 KS |
1432 | /* the line gets too long, split it up in separate records */ |
1433 | cont_flush(LOG_CONT); | |
084681d1 KS |
1434 | return false; |
1435 | } | |
1436 | ||
1437 | if (!cont.len) { | |
1438 | cont.facility = facility; | |
1439 | cont.level = level; | |
1440 | cont.owner = current; | |
1441 | cont.ts_nsec = local_clock(); | |
eab07260 | 1442 | cont.flags = 0; |
084681d1 KS |
1443 | cont.cons = 0; |
1444 | cont.flushed = false; | |
1445 | } | |
1446 | ||
1447 | memcpy(cont.buf + cont.len, text, len); | |
1448 | cont.len += len; | |
eab07260 KS |
1449 | |
1450 | if (cont.len > (sizeof(cont.buf) * 80) / 100) | |
1451 | cont_flush(LOG_CONT); | |
1452 | ||
084681d1 KS |
1453 | return true; |
1454 | } | |
1455 | ||
1456 | static size_t cont_print_text(char *text, size_t size) | |
1457 | { | |
1458 | size_t textlen = 0; | |
1459 | size_t len; | |
1460 | ||
eab07260 | 1461 | if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) { |
084681d1 KS |
1462 | textlen += print_time(cont.ts_nsec, text); |
1463 | size -= textlen; | |
1464 | } | |
1465 | ||
1466 | len = cont.len - cont.cons; | |
1467 | if (len > 0) { | |
1468 | if (len+1 > size) | |
1469 | len = size-1; | |
1470 | memcpy(text + textlen, cont.buf + cont.cons, len); | |
1471 | textlen += len; | |
1472 | cont.cons = cont.len; | |
1473 | } | |
1474 | ||
1475 | if (cont.flushed) { | |
eab07260 KS |
1476 | if (cont.flags & LOG_NEWLINE) |
1477 | text[textlen++] = '\n'; | |
084681d1 KS |
1478 | /* got everything, release buffer */ |
1479 | cont.len = 0; | |
1480 | } | |
1481 | return textlen; | |
1482 | } | |
1483 | ||
7ff9554b KS |
1484 | asmlinkage int vprintk_emit(int facility, int level, |
1485 | const char *dict, size_t dictlen, | |
1486 | const char *fmt, va_list args) | |
1da177e4 | 1487 | { |
7ff9554b | 1488 | static int recursion_bug; |
7ff9554b KS |
1489 | static char textbuf[LOG_LINE_MAX]; |
1490 | char *text = textbuf; | |
c313af14 | 1491 | size_t text_len; |
5becfb1d | 1492 | enum log_flags lflags = 0; |
ac60ad74 | 1493 | unsigned long flags; |
32a76006 | 1494 | int this_cpu; |
7ff9554b | 1495 | int printed_len = 0; |
1da177e4 | 1496 | |
bfe8df3d | 1497 | boot_delay_msec(); |
af91322e | 1498 | printk_delay(); |
bfe8df3d | 1499 | |
1da177e4 | 1500 | /* This stops the holder of console_sem just where we want him */ |
1a9a8aef | 1501 | local_irq_save(flags); |
32a76006 IM |
1502 | this_cpu = smp_processor_id(); |
1503 | ||
1504 | /* | |
1505 | * Ouch, printk recursed into itself! | |
1506 | */ | |
7ff9554b | 1507 | if (unlikely(logbuf_cpu == this_cpu)) { |
32a76006 IM |
1508 | /* |
1509 | * If a crash is occurring during printk() on this CPU, | |
1510 | * then try to get the crash message out but make sure | |
1511 | * we can't deadlock. Otherwise just return to avoid the | |
1512 | * recursion and return - but flag the recursion so that | |
1513 | * it can be printed at the next appropriate moment: | |
1514 | */ | |
94d24fc4 | 1515 | if (!oops_in_progress && !lockdep_recursing(current)) { |
3b8945e8 | 1516 | recursion_bug = 1; |
32a76006 IM |
1517 | goto out_restore_irqs; |
1518 | } | |
1519 | zap_locks(); | |
1520 | } | |
1521 | ||
a0f1ccfd | 1522 | lockdep_off(); |
07354eb1 | 1523 | raw_spin_lock(&logbuf_lock); |
7ff9554b | 1524 | logbuf_cpu = this_cpu; |
1da177e4 | 1525 | |
3b8945e8 | 1526 | if (recursion_bug) { |
7ff9554b KS |
1527 | static const char recursion_msg[] = |
1528 | "BUG: recent printk recursion!"; | |
1529 | ||
3b8945e8 | 1530 | recursion_bug = 0; |
7ff9554b KS |
1531 | printed_len += strlen(recursion_msg); |
1532 | /* emit KERN_CRIT message */ | |
5becfb1d | 1533 | log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0, |
084681d1 | 1534 | NULL, 0, recursion_msg, printed_len); |
32a76006 | 1535 | } |
1da177e4 | 1536 | |
7ff9554b KS |
1537 | /* |
1538 | * The printf needs to come first; we need the syslog | |
1539 | * prefix which might be passed-in as a parameter. | |
1540 | */ | |
c313af14 | 1541 | text_len = vscnprintf(text, sizeof(textbuf), fmt, args); |
5fd29d6c | 1542 | |
7ff9554b | 1543 | /* mark and strip a trailing newline */ |
c313af14 KS |
1544 | if (text_len && text[text_len-1] == '\n') { |
1545 | text_len--; | |
5becfb1d | 1546 | lflags |= LOG_NEWLINE; |
7ff9554b | 1547 | } |
9d90c8d9 | 1548 | |
c313af14 | 1549 | /* strip syslog prefix and extract log level or control flags */ |
7ff9554b KS |
1550 | if (text[0] == '<' && text[1] && text[2] == '>') { |
1551 | switch (text[1]) { | |
1552 | case '0' ... '7': | |
1553 | if (level == -1) | |
1554 | level = text[1] - '0'; | |
7ff9554b | 1555 | case 'd': /* KERN_DEFAULT */ |
5becfb1d | 1556 | lflags |= LOG_PREFIX; |
5c5d5ca5 | 1557 | case 'c': /* KERN_CONT */ |
7ff9554b | 1558 | text += 3; |
c313af14 | 1559 | text_len -= 3; |
5fd29d6c LT |
1560 | } |
1561 | } | |
1562 | ||
c313af14 KS |
1563 | if (level == -1) |
1564 | level = default_message_loglevel; | |
9d90c8d9 | 1565 | |
5becfb1d KS |
1566 | if (dict) |
1567 | lflags |= LOG_PREFIX|LOG_NEWLINE; | |
ac60ad74 | 1568 | |
5becfb1d | 1569 | if (!(lflags & LOG_NEWLINE)) { |
084681d1 KS |
1570 | /* |
1571 | * Flush the conflicting buffer. An earlier newline was missing, | |
1572 | * or another task also prints continuation lines. | |
1573 | */ | |
5becfb1d | 1574 | if (cont.len && (lflags & LOG_PREFIX || cont.owner != current)) |
eab07260 | 1575 | cont_flush(LOG_NEWLINE); |
c313af14 | 1576 | |
084681d1 KS |
1577 | /* buffer line if possible, otherwise store it right away */ |
1578 | if (!cont_add(facility, level, text, text_len)) | |
5becfb1d | 1579 | log_store(facility, level, lflags | LOG_CONT, 0, |
084681d1 | 1580 | dict, dictlen, text, text_len); |
5c5d5ca5 | 1581 | } else { |
084681d1 | 1582 | bool stored = false; |
c313af14 | 1583 | |
084681d1 | 1584 | /* |
d3620822 SR |
1585 | * If an earlier newline was missing and it was the same task, |
1586 | * either merge it with the current buffer and flush, or if | |
1587 | * there was a race with interrupts (prefix == true) then just | |
1588 | * flush it out and store this line separately. | |
084681d1 | 1589 | */ |
084681d1 | 1590 | if (cont.len && cont.owner == current) { |
5becfb1d | 1591 | if (!(lflags & LOG_PREFIX)) |
d3620822 | 1592 | stored = cont_add(facility, level, text, text_len); |
eab07260 | 1593 | cont_flush(LOG_NEWLINE); |
c313af14 | 1594 | } |
084681d1 KS |
1595 | |
1596 | if (!stored) | |
5becfb1d | 1597 | log_store(facility, level, lflags, 0, |
084681d1 | 1598 | dict, dictlen, text, text_len); |
1da177e4 | 1599 | } |
084681d1 | 1600 | printed_len += text_len; |
1da177e4 | 1601 | |
266c2e0a | 1602 | /* |
7ff9554b KS |
1603 | * Try to acquire and then immediately release the console semaphore. |
1604 | * The release will print out buffers and wake up /dev/kmsg and syslog() | |
1605 | * users. | |
266c2e0a | 1606 | * |
7ff9554b KS |
1607 | * The console_trylock_for_printk() function will release 'logbuf_lock' |
1608 | * regardless of whether it actually gets the console semaphore or not. | |
266c2e0a | 1609 | */ |
ac751efa TH |
1610 | if (console_trylock_for_printk(this_cpu)) |
1611 | console_unlock(); | |
76a8ad29 | 1612 | |
266c2e0a | 1613 | lockdep_on(); |
32a76006 | 1614 | out_restore_irqs: |
1a9a8aef | 1615 | local_irq_restore(flags); |
76a8ad29 | 1616 | |
1da177e4 LT |
1617 | return printed_len; |
1618 | } | |
7ff9554b KS |
1619 | EXPORT_SYMBOL(vprintk_emit); |
1620 | ||
1621 | asmlinkage int vprintk(const char *fmt, va_list args) | |
1622 | { | |
1623 | return vprintk_emit(0, -1, NULL, 0, fmt, args); | |
1624 | } | |
1da177e4 LT |
1625 | EXPORT_SYMBOL(vprintk); |
1626 | ||
7ff9554b KS |
1627 | asmlinkage int printk_emit(int facility, int level, |
1628 | const char *dict, size_t dictlen, | |
1629 | const char *fmt, ...) | |
1630 | { | |
1631 | va_list args; | |
1632 | int r; | |
1633 | ||
1634 | va_start(args, fmt); | |
1635 | r = vprintk_emit(facility, level, dict, dictlen, fmt, args); | |
1636 | va_end(args); | |
1637 | ||
1638 | return r; | |
1639 | } | |
1640 | EXPORT_SYMBOL(printk_emit); | |
1641 | ||
1642 | /** | |
1643 | * printk - print a kernel message | |
1644 | * @fmt: format string | |
1645 | * | |
1646 | * This is printk(). It can be called from any context. We want it to work. | |
1647 | * | |
1648 | * We try to grab the console_lock. If we succeed, it's easy - we log the | |
1649 | * output and call the console drivers. If we fail to get the semaphore, we | |
1650 | * place the output into the log buffer and return. The current holder of | |
1651 | * the console_sem will notice the new output in console_unlock(); and will | |
1652 | * send it to the consoles before releasing the lock. | |
1653 | * | |
1654 | * One effect of this deferred printing is that code which calls printk() and | |
1655 | * then changes console_loglevel may break. This is because console_loglevel | |
1656 | * is inspected when the actual printing occurs. | |
1657 | * | |
1658 | * See also: | |
1659 | * printf(3) | |
1660 | * | |
1661 | * See the vsnprintf() documentation for format string extensions over C99. | |
1662 | */ | |
1663 | asmlinkage int printk(const char *fmt, ...) | |
1664 | { | |
1665 | va_list args; | |
1666 | int r; | |
1667 | ||
1668 | #ifdef CONFIG_KGDB_KDB | |
1669 | if (unlikely(kdb_trap_printk)) { | |
1670 | va_start(args, fmt); | |
1671 | r = vkdb_printf(fmt, args); | |
1672 | va_end(args); | |
1673 | return r; | |
1674 | } | |
1675 | #endif | |
1676 | va_start(args, fmt); | |
1677 | r = vprintk_emit(0, -1, NULL, 0, fmt, args); | |
1678 | va_end(args); | |
1679 | ||
1680 | return r; | |
1681 | } | |
1682 | EXPORT_SYMBOL(printk); | |
7f3a781d | 1683 | |
96efedf1 | 1684 | #else /* CONFIG_PRINTK */ |
d59745ce | 1685 | |
70498253 KS |
1686 | #define LOG_LINE_MAX 0 |
1687 | #define PREFIX_MAX 0 | |
96efedf1 KS |
1688 | #define LOG_LINE_MAX 0 |
1689 | static u64 syslog_seq; | |
1690 | static u32 syslog_idx; | |
eab07260 KS |
1691 | static u64 console_seq; |
1692 | static u32 console_idx; | |
96efedf1 KS |
1693 | static enum log_flags syslog_prev; |
1694 | static u64 log_first_seq; | |
1695 | static u32 log_first_idx; | |
1696 | static u64 log_next_seq; | |
eab07260 | 1697 | static enum log_flags console_prev; |
084681d1 KS |
1698 | static struct cont { |
1699 | size_t len; | |
1700 | size_t cons; | |
1701 | u8 level; | |
1702 | bool flushed:1; | |
1703 | } cont; | |
7f3a781d KS |
1704 | static struct log *log_from_idx(u32 idx) { return NULL; } |
1705 | static u32 log_next(u32 idx) { return 0; } | |
7f3a781d | 1706 | static void call_console_drivers(int level, const char *text, size_t len) {} |
5becfb1d KS |
1707 | static size_t msg_print_text(const struct log *msg, enum log_flags prev, |
1708 | bool syslog, char *buf, size_t size) { return 0; } | |
084681d1 | 1709 | static size_t cont_print_text(char *text, size_t size) { return 0; } |
d59745ce | 1710 | |
7f3a781d | 1711 | #endif /* CONFIG_PRINTK */ |
d59745ce | 1712 | |
f7511d5f ST |
1713 | static int __add_preferred_console(char *name, int idx, char *options, |
1714 | char *brl_options) | |
1715 | { | |
1716 | struct console_cmdline *c; | |
1717 | int i; | |
1718 | ||
1719 | /* | |
1720 | * See if this tty is not yet registered, and | |
1721 | * if we have a slot free. | |
1722 | */ | |
1723 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
1724 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
1725 | console_cmdline[i].index == idx) { | |
1726 | if (!brl_options) | |
1727 | selected_console = i; | |
1728 | return 0; | |
1729 | } | |
1730 | if (i == MAX_CMDLINECONSOLES) | |
1731 | return -E2BIG; | |
1732 | if (!brl_options) | |
1733 | selected_console = i; | |
1734 | c = &console_cmdline[i]; | |
1735 | strlcpy(c->name, name, sizeof(c->name)); | |
1736 | c->options = options; | |
1737 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
1738 | c->brl_options = brl_options; | |
1739 | #endif | |
1740 | c->index = idx; | |
1741 | return 0; | |
1742 | } | |
2ea1c539 JB |
1743 | /* |
1744 | * Set up a list of consoles. Called from init/main.c | |
1745 | */ | |
1746 | static int __init console_setup(char *str) | |
1747 | { | |
eaa944af | 1748 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 1749 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
1750 | int idx; |
1751 | ||
f7511d5f ST |
1752 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1753 | if (!memcmp(str, "brl,", 4)) { | |
1754 | brl_options = ""; | |
1755 | str += 4; | |
1756 | } else if (!memcmp(str, "brl=", 4)) { | |
1757 | brl_options = str + 4; | |
1758 | str = strchr(brl_options, ','); | |
1759 | if (!str) { | |
1760 | printk(KERN_ERR "need port name after brl=\n"); | |
1761 | return 1; | |
1762 | } | |
1763 | *(str++) = 0; | |
1764 | } | |
1765 | #endif | |
1766 | ||
2ea1c539 JB |
1767 | /* |
1768 | * Decode str into name, index, options. | |
1769 | */ | |
1770 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
1771 | strcpy(buf, "ttyS"); |
1772 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 1773 | } else { |
eaa944af | 1774 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 1775 | } |
eaa944af | 1776 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
1777 | if ((options = strchr(str, ',')) != NULL) |
1778 | *(options++) = 0; | |
1779 | #ifdef __sparc__ | |
1780 | if (!strcmp(str, "ttya")) | |
eaa944af | 1781 | strcpy(buf, "ttyS0"); |
2ea1c539 | 1782 | if (!strcmp(str, "ttyb")) |
eaa944af | 1783 | strcpy(buf, "ttyS1"); |
2ea1c539 | 1784 | #endif |
eaa944af | 1785 | for (s = buf; *s; s++) |
2ea1c539 JB |
1786 | if ((*s >= '0' && *s <= '9') || *s == ',') |
1787 | break; | |
1788 | idx = simple_strtoul(s, NULL, 10); | |
1789 | *s = 0; | |
1790 | ||
f7511d5f | 1791 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 1792 | console_set_on_cmdline = 1; |
2ea1c539 JB |
1793 | return 1; |
1794 | } | |
1795 | __setup("console=", console_setup); | |
1796 | ||
3c0547ba MM |
1797 | /** |
1798 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
1799 | * @name: device name |
1800 | * @idx: device index | |
1801 | * @options: options for this console | |
3c0547ba MM |
1802 | * |
1803 | * The last preferred console added will be used for kernel messages | |
1804 | * and stdin/out/err for init. Normally this is used by console_setup | |
1805 | * above to handle user-supplied console arguments; however it can also | |
1806 | * be used by arch-specific code either to override the user or more | |
1807 | * commonly to provide a default console (ie from PROM variables) when | |
1808 | * the user has not supplied one. | |
1809 | */ | |
fb445ee5 | 1810 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 1811 | { |
f7511d5f | 1812 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
1813 | } |
1814 | ||
b6b1d877 | 1815 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
1816 | { |
1817 | struct console_cmdline *c; | |
1818 | int i; | |
1819 | ||
1820 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
1821 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
1822 | console_cmdline[i].index == idx) { | |
1823 | c = &console_cmdline[i]; | |
f735295b | 1824 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
1825 | c->name[sizeof(c->name) - 1] = 0; |
1826 | c->options = options; | |
1827 | c->index = idx_new; | |
1828 | return i; | |
1829 | } | |
1830 | /* not found */ | |
1831 | return -1; | |
1832 | } | |
1833 | ||
2329abfa | 1834 | bool console_suspend_enabled = 1; |
8f4ce8c3 AS |
1835 | EXPORT_SYMBOL(console_suspend_enabled); |
1836 | ||
1837 | static int __init console_suspend_disable(char *str) | |
1838 | { | |
1839 | console_suspend_enabled = 0; | |
1840 | return 1; | |
1841 | } | |
1842 | __setup("no_console_suspend", console_suspend_disable); | |
134620f7 YZ |
1843 | module_param_named(console_suspend, console_suspend_enabled, |
1844 | bool, S_IRUGO | S_IWUSR); | |
1845 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" | |
1846 | " and hibernate operations"); | |
8f4ce8c3 | 1847 | |
557240b4 LT |
1848 | /** |
1849 | * suspend_console - suspend the console subsystem | |
1850 | * | |
1851 | * This disables printk() while we go into suspend states | |
1852 | */ | |
1853 | void suspend_console(void) | |
1854 | { | |
8f4ce8c3 AS |
1855 | if (!console_suspend_enabled) |
1856 | return; | |
0d63081d | 1857 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
ac751efa | 1858 | console_lock(); |
557240b4 | 1859 | console_suspended = 1; |
403f3075 | 1860 | up(&console_sem); |
557240b4 LT |
1861 | } |
1862 | ||
1863 | void resume_console(void) | |
1864 | { | |
8f4ce8c3 AS |
1865 | if (!console_suspend_enabled) |
1866 | return; | |
403f3075 | 1867 | down(&console_sem); |
557240b4 | 1868 | console_suspended = 0; |
ac751efa | 1869 | console_unlock(); |
557240b4 LT |
1870 | } |
1871 | ||
034260d6 KC |
1872 | /** |
1873 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
1874 | * @self: notifier struct | |
1875 | * @action: CPU hotplug event | |
1876 | * @hcpu: unused | |
1877 | * | |
1878 | * If printk() is called from a CPU that is not online yet, the messages | |
1879 | * will be spooled but will not show up on the console. This function is | |
1880 | * called when a new CPU comes online (or fails to come up), and ensures | |
1881 | * that any such output gets printed. | |
1882 | */ | |
1883 | static int __cpuinit console_cpu_notify(struct notifier_block *self, | |
1884 | unsigned long action, void *hcpu) | |
1885 | { | |
1886 | switch (action) { | |
1887 | case CPU_ONLINE: | |
1888 | case CPU_DEAD: | |
1889 | case CPU_DYING: | |
1890 | case CPU_DOWN_FAILED: | |
1891 | case CPU_UP_CANCELED: | |
ac751efa TH |
1892 | console_lock(); |
1893 | console_unlock(); | |
034260d6 KC |
1894 | } |
1895 | return NOTIFY_OK; | |
1896 | } | |
1897 | ||
1da177e4 | 1898 | /** |
ac751efa | 1899 | * console_lock - lock the console system for exclusive use. |
1da177e4 | 1900 | * |
ac751efa | 1901 | * Acquires a lock which guarantees that the caller has |
1da177e4 LT |
1902 | * exclusive access to the console system and the console_drivers list. |
1903 | * | |
1904 | * Can sleep, returns nothing. | |
1905 | */ | |
ac751efa | 1906 | void console_lock(void) |
1da177e4 | 1907 | { |
8abd8e29 | 1908 | BUG_ON(in_interrupt()); |
1da177e4 | 1909 | down(&console_sem); |
403f3075 AH |
1910 | if (console_suspended) |
1911 | return; | |
1da177e4 LT |
1912 | console_locked = 1; |
1913 | console_may_schedule = 1; | |
1914 | } | |
ac751efa | 1915 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 1916 | |
ac751efa TH |
1917 | /** |
1918 | * console_trylock - try to lock the console system for exclusive use. | |
1919 | * | |
1920 | * Tried to acquire a lock which guarantees that the caller has | |
1921 | * exclusive access to the console system and the console_drivers list. | |
1922 | * | |
1923 | * returns 1 on success, and 0 on failure to acquire the lock. | |
1924 | */ | |
1925 | int console_trylock(void) | |
1da177e4 LT |
1926 | { |
1927 | if (down_trylock(&console_sem)) | |
ac751efa | 1928 | return 0; |
403f3075 AH |
1929 | if (console_suspended) { |
1930 | up(&console_sem); | |
ac751efa | 1931 | return 0; |
403f3075 | 1932 | } |
1da177e4 LT |
1933 | console_locked = 1; |
1934 | console_may_schedule = 0; | |
ac751efa | 1935 | return 1; |
1da177e4 | 1936 | } |
ac751efa | 1937 | EXPORT_SYMBOL(console_trylock); |
1da177e4 LT |
1938 | |
1939 | int is_console_locked(void) | |
1940 | { | |
1941 | return console_locked; | |
1942 | } | |
1da177e4 | 1943 | |
3ccf3e83 | 1944 | /* |
7ff9554b | 1945 | * Delayed printk version, for scheduler-internal messages: |
3ccf3e83 PZ |
1946 | */ |
1947 | #define PRINTK_BUF_SIZE 512 | |
1948 | ||
1949 | #define PRINTK_PENDING_WAKEUP 0x01 | |
1950 | #define PRINTK_PENDING_SCHED 0x02 | |
1951 | ||
b845b517 | 1952 | static DEFINE_PER_CPU(int, printk_pending); |
3ccf3e83 | 1953 | static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf); |
b845b517 PZ |
1954 | |
1955 | void printk_tick(void) | |
e3e8a75d | 1956 | { |
40dc11ff | 1957 | if (__this_cpu_read(printk_pending)) { |
3ccf3e83 PZ |
1958 | int pending = __this_cpu_xchg(printk_pending, 0); |
1959 | if (pending & PRINTK_PENDING_SCHED) { | |
1960 | char *buf = __get_cpu_var(printk_sched_buf); | |
1961 | printk(KERN_WARNING "[sched_delayed] %s", buf); | |
1962 | } | |
1963 | if (pending & PRINTK_PENDING_WAKEUP) | |
1964 | wake_up_interruptible(&log_wait); | |
b845b517 PZ |
1965 | } |
1966 | } | |
1967 | ||
1968 | int printk_needs_cpu(int cpu) | |
1969 | { | |
40dc11ff | 1970 | if (cpu_is_offline(cpu)) |
61ab2544 | 1971 | printk_tick(); |
40dc11ff | 1972 | return __this_cpu_read(printk_pending); |
b845b517 PZ |
1973 | } |
1974 | ||
1975 | void wake_up_klogd(void) | |
1976 | { | |
1977 | if (waitqueue_active(&log_wait)) | |
3ccf3e83 | 1978 | this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); |
e3e8a75d KK |
1979 | } |
1980 | ||
eab07260 KS |
1981 | static void console_cont_flush(char *text, size_t size) |
1982 | { | |
1983 | unsigned long flags; | |
1984 | size_t len; | |
1985 | ||
1986 | raw_spin_lock_irqsave(&logbuf_lock, flags); | |
1987 | ||
1988 | if (!cont.len) | |
1989 | goto out; | |
1990 | ||
1991 | /* | |
1992 | * We still queue earlier records, likely because the console was | |
1993 | * busy. The earlier ones need to be printed before this one, we | |
1994 | * did not flush any fragment so far, so just let it queue up. | |
1995 | */ | |
1996 | if (console_seq < log_next_seq && !cont.cons) | |
1997 | goto out; | |
1998 | ||
1999 | len = cont_print_text(text, size); | |
2000 | raw_spin_unlock(&logbuf_lock); | |
2001 | stop_critical_timings(); | |
2002 | call_console_drivers(cont.level, text, len); | |
2003 | start_critical_timings(); | |
2004 | local_irq_restore(flags); | |
2005 | return; | |
2006 | out: | |
2007 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); | |
2008 | } | |
7ff9554b | 2009 | |
1da177e4 | 2010 | /** |
ac751efa | 2011 | * console_unlock - unlock the console system |
1da177e4 | 2012 | * |
ac751efa | 2013 | * Releases the console_lock which the caller holds on the console system |
1da177e4 LT |
2014 | * and the console driver list. |
2015 | * | |
ac751efa TH |
2016 | * While the console_lock was held, console output may have been buffered |
2017 | * by printk(). If this is the case, console_unlock(); emits | |
2018 | * the output prior to releasing the lock. | |
1da177e4 | 2019 | * |
7f3a781d | 2020 | * If there is output waiting, we wake /dev/kmsg and syslog() users. |
1da177e4 | 2021 | * |
ac751efa | 2022 | * console_unlock(); may be called from any context. |
1da177e4 | 2023 | */ |
ac751efa | 2024 | void console_unlock(void) |
1da177e4 | 2025 | { |
70498253 | 2026 | static char text[LOG_LINE_MAX + PREFIX_MAX]; |
7ff9554b | 2027 | static u64 seen_seq; |
1da177e4 | 2028 | unsigned long flags; |
7ff9554b KS |
2029 | bool wake_klogd = false; |
2030 | bool retry; | |
1da177e4 | 2031 | |
557240b4 | 2032 | if (console_suspended) { |
403f3075 | 2033 | up(&console_sem); |
557240b4 LT |
2034 | return; |
2035 | } | |
78944e54 AD |
2036 | |
2037 | console_may_schedule = 0; | |
2038 | ||
084681d1 | 2039 | /* flush buffered message fragment immediately to console */ |
eab07260 | 2040 | console_cont_flush(text, sizeof(text)); |
4f2a8d3c | 2041 | again: |
7ff9554b KS |
2042 | for (;;) { |
2043 | struct log *msg; | |
3ce9a7c0 | 2044 | size_t len; |
7ff9554b KS |
2045 | int level; |
2046 | ||
07354eb1 | 2047 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
7ff9554b KS |
2048 | if (seen_seq != log_next_seq) { |
2049 | wake_klogd = true; | |
2050 | seen_seq = log_next_seq; | |
2051 | } | |
2052 | ||
2053 | if (console_seq < log_first_seq) { | |
2054 | /* messages are gone, move to first one */ | |
2055 | console_seq = log_first_seq; | |
2056 | console_idx = log_first_idx; | |
5becfb1d | 2057 | console_prev = 0; |
7ff9554b | 2058 | } |
084681d1 | 2059 | skip: |
7ff9554b KS |
2060 | if (console_seq == log_next_seq) |
2061 | break; | |
2062 | ||
2063 | msg = log_from_idx(console_idx); | |
084681d1 KS |
2064 | if (msg->flags & LOG_NOCONS) { |
2065 | /* | |
2066 | * Skip record we have buffered and already printed | |
2067 | * directly to the console when we received it. | |
2068 | */ | |
2069 | console_idx = log_next(console_idx); | |
2070 | console_seq++; | |
68b6507d KS |
2071 | /* |
2072 | * We will get here again when we register a new | |
2073 | * CON_PRINTBUFFER console. Clear the flag so we | |
2074 | * will properly dump everything later. | |
2075 | */ | |
2076 | msg->flags &= ~LOG_NOCONS; | |
eab07260 | 2077 | console_prev = msg->flags; |
084681d1 KS |
2078 | goto skip; |
2079 | } | |
649e6ee3 | 2080 | |
084681d1 | 2081 | level = msg->level; |
5becfb1d KS |
2082 | len = msg_print_text(msg, console_prev, false, |
2083 | text, sizeof(text)); | |
7ff9554b KS |
2084 | console_idx = log_next(console_idx); |
2085 | console_seq++; | |
5becfb1d | 2086 | console_prev = msg->flags; |
07354eb1 | 2087 | raw_spin_unlock(&logbuf_lock); |
7ff9554b | 2088 | |
81d68a96 | 2089 | stop_critical_timings(); /* don't trace print latency */ |
7ff9554b | 2090 | call_console_drivers(level, text, len); |
81d68a96 | 2091 | start_critical_timings(); |
1da177e4 LT |
2092 | local_irq_restore(flags); |
2093 | } | |
2094 | console_locked = 0; | |
fe3d8ad3 FT |
2095 | |
2096 | /* Release the exclusive_console once it is used */ | |
2097 | if (unlikely(exclusive_console)) | |
2098 | exclusive_console = NULL; | |
2099 | ||
07354eb1 | 2100 | raw_spin_unlock(&logbuf_lock); |
4f2a8d3c | 2101 | |
0b5e1c52 | 2102 | up(&console_sem); |
4f2a8d3c PZ |
2103 | |
2104 | /* | |
2105 | * Someone could have filled up the buffer again, so re-check if there's | |
2106 | * something to flush. In case we cannot trylock the console_sem again, | |
2107 | * there's a new owner and the console_unlock() from them will do the | |
2108 | * flush, no worries. | |
2109 | */ | |
07354eb1 | 2110 | raw_spin_lock(&logbuf_lock); |
7ff9554b | 2111 | retry = console_seq != log_next_seq; |
09dc3cf9 PZ |
2112 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
2113 | ||
4f2a8d3c PZ |
2114 | if (retry && console_trylock()) |
2115 | goto again; | |
2116 | ||
e3e8a75d KK |
2117 | if (wake_klogd) |
2118 | wake_up_klogd(); | |
1da177e4 | 2119 | } |
ac751efa | 2120 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 2121 | |
ddad86c2 MW |
2122 | /** |
2123 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
2124 | * |
2125 | * If the console code is currently allowed to sleep, and | |
2126 | * if this CPU should yield the CPU to another task, do | |
2127 | * so here. | |
2128 | * | |
ac751efa | 2129 | * Must be called within console_lock();. |
1da177e4 LT |
2130 | */ |
2131 | void __sched console_conditional_schedule(void) | |
2132 | { | |
2133 | if (console_may_schedule) | |
2134 | cond_resched(); | |
2135 | } | |
2136 | EXPORT_SYMBOL(console_conditional_schedule); | |
2137 | ||
1da177e4 LT |
2138 | void console_unblank(void) |
2139 | { | |
2140 | struct console *c; | |
2141 | ||
2142 | /* | |
2143 | * console_unblank can no longer be called in interrupt context unless | |
2144 | * oops_in_progress is set to 1.. | |
2145 | */ | |
2146 | if (oops_in_progress) { | |
2147 | if (down_trylock(&console_sem) != 0) | |
2148 | return; | |
2149 | } else | |
ac751efa | 2150 | console_lock(); |
1da177e4 LT |
2151 | |
2152 | console_locked = 1; | |
2153 | console_may_schedule = 0; | |
4d091611 | 2154 | for_each_console(c) |
1da177e4 LT |
2155 | if ((c->flags & CON_ENABLED) && c->unblank) |
2156 | c->unblank(); | |
ac751efa | 2157 | console_unlock(); |
1da177e4 | 2158 | } |
1da177e4 LT |
2159 | |
2160 | /* | |
2161 | * Return the console tty driver structure and its associated index | |
2162 | */ | |
2163 | struct tty_driver *console_device(int *index) | |
2164 | { | |
2165 | struct console *c; | |
2166 | struct tty_driver *driver = NULL; | |
2167 | ||
ac751efa | 2168 | console_lock(); |
4d091611 | 2169 | for_each_console(c) { |
1da177e4 LT |
2170 | if (!c->device) |
2171 | continue; | |
2172 | driver = c->device(c, index); | |
2173 | if (driver) | |
2174 | break; | |
2175 | } | |
ac751efa | 2176 | console_unlock(); |
1da177e4 LT |
2177 | return driver; |
2178 | } | |
2179 | ||
2180 | /* | |
2181 | * Prevent further output on the passed console device so that (for example) | |
2182 | * serial drivers can disable console output before suspending a port, and can | |
2183 | * re-enable output afterwards. | |
2184 | */ | |
2185 | void console_stop(struct console *console) | |
2186 | { | |
ac751efa | 2187 | console_lock(); |
1da177e4 | 2188 | console->flags &= ~CON_ENABLED; |
ac751efa | 2189 | console_unlock(); |
1da177e4 LT |
2190 | } |
2191 | EXPORT_SYMBOL(console_stop); | |
2192 | ||
2193 | void console_start(struct console *console) | |
2194 | { | |
ac751efa | 2195 | console_lock(); |
1da177e4 | 2196 | console->flags |= CON_ENABLED; |
ac751efa | 2197 | console_unlock(); |
1da177e4 LT |
2198 | } |
2199 | EXPORT_SYMBOL(console_start); | |
2200 | ||
7bf69395 FDN |
2201 | static int __read_mostly keep_bootcon; |
2202 | ||
2203 | static int __init keep_bootcon_setup(char *str) | |
2204 | { | |
2205 | keep_bootcon = 1; | |
2206 | printk(KERN_INFO "debug: skip boot console de-registration.\n"); | |
2207 | ||
2208 | return 0; | |
2209 | } | |
2210 | ||
2211 | early_param("keep_bootcon", keep_bootcon_setup); | |
2212 | ||
1da177e4 LT |
2213 | /* |
2214 | * The console driver calls this routine during kernel initialization | |
2215 | * to register the console printing procedure with printk() and to | |
2216 | * print any messages that were printed by the kernel before the | |
2217 | * console driver was initialized. | |
4d091611 RG |
2218 | * |
2219 | * This can happen pretty early during the boot process (because of | |
2220 | * early_printk) - sometimes before setup_arch() completes - be careful | |
2221 | * of what kernel features are used - they may not be initialised yet. | |
2222 | * | |
2223 | * There are two types of consoles - bootconsoles (early_printk) and | |
2224 | * "real" consoles (everything which is not a bootconsole) which are | |
2225 | * handled differently. | |
2226 | * - Any number of bootconsoles can be registered at any time. | |
2227 | * - As soon as a "real" console is registered, all bootconsoles | |
2228 | * will be unregistered automatically. | |
2229 | * - Once a "real" console is registered, any attempt to register a | |
2230 | * bootconsoles will be rejected | |
1da177e4 | 2231 | */ |
4d091611 | 2232 | void register_console(struct console *newcon) |
1da177e4 | 2233 | { |
40dc5651 | 2234 | int i; |
1da177e4 | 2235 | unsigned long flags; |
4d091611 | 2236 | struct console *bcon = NULL; |
1da177e4 | 2237 | |
4d091611 RG |
2238 | /* |
2239 | * before we register a new CON_BOOT console, make sure we don't | |
2240 | * already have a valid console | |
2241 | */ | |
2242 | if (console_drivers && newcon->flags & CON_BOOT) { | |
2243 | /* find the last or real console */ | |
2244 | for_each_console(bcon) { | |
2245 | if (!(bcon->flags & CON_BOOT)) { | |
2246 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", | |
2247 | newcon->name, newcon->index); | |
2248 | return; | |
2249 | } | |
2250 | } | |
69331af7 GH |
2251 | } |
2252 | ||
4d091611 RG |
2253 | if (console_drivers && console_drivers->flags & CON_BOOT) |
2254 | bcon = console_drivers; | |
2255 | ||
2256 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
2257 | preferred_console = selected_console; |
2258 | ||
4d091611 RG |
2259 | if (newcon->early_setup) |
2260 | newcon->early_setup(); | |
18a8bd94 | 2261 | |
1da177e4 LT |
2262 | /* |
2263 | * See if we want to use this console driver. If we | |
2264 | * didn't select a console we take the first one | |
2265 | * that registers here. | |
2266 | */ | |
2267 | if (preferred_console < 0) { | |
4d091611 RG |
2268 | if (newcon->index < 0) |
2269 | newcon->index = 0; | |
2270 | if (newcon->setup == NULL || | |
2271 | newcon->setup(newcon, NULL) == 0) { | |
2272 | newcon->flags |= CON_ENABLED; | |
2273 | if (newcon->device) { | |
2274 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
2275 | preferred_console = 0; |
2276 | } | |
1da177e4 LT |
2277 | } |
2278 | } | |
2279 | ||
2280 | /* | |
2281 | * See if this console matches one we selected on | |
2282 | * the command line. | |
2283 | */ | |
40dc5651 JJ |
2284 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
2285 | i++) { | |
4d091611 | 2286 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1da177e4 | 2287 | continue; |
4d091611 RG |
2288 | if (newcon->index >= 0 && |
2289 | newcon->index != console_cmdline[i].index) | |
1da177e4 | 2290 | continue; |
4d091611 RG |
2291 | if (newcon->index < 0) |
2292 | newcon->index = console_cmdline[i].index; | |
f7511d5f ST |
2293 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
2294 | if (console_cmdline[i].brl_options) { | |
4d091611 RG |
2295 | newcon->flags |= CON_BRL; |
2296 | braille_register_console(newcon, | |
f7511d5f ST |
2297 | console_cmdline[i].index, |
2298 | console_cmdline[i].options, | |
2299 | console_cmdline[i].brl_options); | |
2300 | return; | |
2301 | } | |
2302 | #endif | |
4d091611 RG |
2303 | if (newcon->setup && |
2304 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 2305 | break; |
4d091611 RG |
2306 | newcon->flags |= CON_ENABLED; |
2307 | newcon->index = console_cmdline[i].index; | |
ab4af03a | 2308 | if (i == selected_console) { |
4d091611 | 2309 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
2310 | preferred_console = selected_console; |
2311 | } | |
1da177e4 LT |
2312 | break; |
2313 | } | |
2314 | ||
4d091611 | 2315 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
2316 | return; |
2317 | ||
8259cf43 RG |
2318 | /* |
2319 | * If we have a bootconsole, and are switching to a real console, | |
2320 | * don't print everything out again, since when the boot console, and | |
2321 | * the real console are the same physical device, it's annoying to | |
2322 | * see the beginning boot messages twice | |
2323 | */ | |
2324 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 2325 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
2326 | |
2327 | /* | |
2328 | * Put this console in the list - keep the | |
2329 | * preferred driver at the head of the list. | |
2330 | */ | |
ac751efa | 2331 | console_lock(); |
4d091611 RG |
2332 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
2333 | newcon->next = console_drivers; | |
2334 | console_drivers = newcon; | |
2335 | if (newcon->next) | |
2336 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 2337 | } else { |
4d091611 RG |
2338 | newcon->next = console_drivers->next; |
2339 | console_drivers->next = newcon; | |
1da177e4 | 2340 | } |
4d091611 | 2341 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 | 2342 | /* |
ac751efa | 2343 | * console_unlock(); will print out the buffered messages |
1da177e4 LT |
2344 | * for us. |
2345 | */ | |
07354eb1 | 2346 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
7ff9554b KS |
2347 | console_seq = syslog_seq; |
2348 | console_idx = syslog_idx; | |
5becfb1d | 2349 | console_prev = syslog_prev; |
07354eb1 | 2350 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
fe3d8ad3 FT |
2351 | /* |
2352 | * We're about to replay the log buffer. Only do this to the | |
2353 | * just-registered console to avoid excessive message spam to | |
2354 | * the already-registered consoles. | |
2355 | */ | |
2356 | exclusive_console = newcon; | |
1da177e4 | 2357 | } |
ac751efa | 2358 | console_unlock(); |
fbc92a34 | 2359 | console_sysfs_notify(); |
8259cf43 RG |
2360 | |
2361 | /* | |
2362 | * By unregistering the bootconsoles after we enable the real console | |
2363 | * we get the "console xxx enabled" message on all the consoles - | |
2364 | * boot consoles, real consoles, etc - this is to ensure that end | |
2365 | * users know there might be something in the kernel's log buffer that | |
2366 | * went to the bootconsole (that they do not see on the real console) | |
2367 | */ | |
7bf69395 FDN |
2368 | if (bcon && |
2369 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && | |
2370 | !keep_bootcon) { | |
8259cf43 RG |
2371 | /* we need to iterate through twice, to make sure we print |
2372 | * everything out, before we unregister the console(s) | |
2373 | */ | |
2374 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", | |
2375 | newcon->name, newcon->index); | |
2376 | for_each_console(bcon) | |
2377 | if (bcon->flags & CON_BOOT) | |
2378 | unregister_console(bcon); | |
2379 | } else { | |
2380 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", | |
2381 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
2382 | newcon->name, newcon->index); | |
2383 | } | |
1da177e4 LT |
2384 | } |
2385 | EXPORT_SYMBOL(register_console); | |
2386 | ||
40dc5651 | 2387 | int unregister_console(struct console *console) |
1da177e4 | 2388 | { |
40dc5651 | 2389 | struct console *a, *b; |
1da177e4 LT |
2390 | int res = 1; |
2391 | ||
f7511d5f ST |
2392 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
2393 | if (console->flags & CON_BRL) | |
2394 | return braille_unregister_console(console); | |
2395 | #endif | |
2396 | ||
ac751efa | 2397 | console_lock(); |
1da177e4 LT |
2398 | if (console_drivers == console) { |
2399 | console_drivers=console->next; | |
2400 | res = 0; | |
e9b15b54 | 2401 | } else if (console_drivers) { |
1da177e4 LT |
2402 | for (a=console_drivers->next, b=console_drivers ; |
2403 | a; b=a, a=b->next) { | |
2404 | if (a == console) { | |
2405 | b->next = a->next; | |
2406 | res = 0; | |
2407 | break; | |
40dc5651 | 2408 | } |
1da177e4 LT |
2409 | } |
2410 | } | |
40dc5651 | 2411 | |
69331af7 | 2412 | /* |
ab4af03a GE |
2413 | * If this isn't the last console and it has CON_CONSDEV set, we |
2414 | * need to set it on the next preferred console. | |
1da177e4 | 2415 | */ |
69331af7 | 2416 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 2417 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 | 2418 | |
ac751efa | 2419 | console_unlock(); |
fbc92a34 | 2420 | console_sysfs_notify(); |
1da177e4 LT |
2421 | return res; |
2422 | } | |
2423 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 2424 | |
034260d6 | 2425 | static int __init printk_late_init(void) |
0c5564bd | 2426 | { |
4d091611 RG |
2427 | struct console *con; |
2428 | ||
2429 | for_each_console(con) { | |
4c30c6f5 | 2430 | if (!keep_bootcon && con->flags & CON_BOOT) { |
cb00e99c | 2431 | printk(KERN_INFO "turn off boot console %s%d\n", |
4d091611 | 2432 | con->name, con->index); |
42c2c8c8 | 2433 | unregister_console(con); |
cb00e99c | 2434 | } |
0c5564bd | 2435 | } |
034260d6 | 2436 | hotcpu_notifier(console_cpu_notify, 0); |
0c5564bd RG |
2437 | return 0; |
2438 | } | |
034260d6 | 2439 | late_initcall(printk_late_init); |
0c5564bd | 2440 | |
7ef3d2fd | 2441 | #if defined CONFIG_PRINTK |
717115e1 | 2442 | |
600e1458 PZ |
2443 | int printk_sched(const char *fmt, ...) |
2444 | { | |
2445 | unsigned long flags; | |
2446 | va_list args; | |
2447 | char *buf; | |
2448 | int r; | |
2449 | ||
2450 | local_irq_save(flags); | |
2451 | buf = __get_cpu_var(printk_sched_buf); | |
2452 | ||
2453 | va_start(args, fmt); | |
2454 | r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args); | |
2455 | va_end(args); | |
2456 | ||
2457 | __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED); | |
2458 | local_irq_restore(flags); | |
2459 | ||
2460 | return r; | |
2461 | } | |
2462 | ||
1da177e4 LT |
2463 | /* |
2464 | * printk rate limiting, lifted from the networking subsystem. | |
2465 | * | |
641de9d8 UKK |
2466 | * This enforces a rate limit: not more than 10 kernel messages |
2467 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 2468 | */ |
641de9d8 UKK |
2469 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
2470 | ||
5c828713 | 2471 | int __printk_ratelimit(const char *func) |
1da177e4 | 2472 | { |
5c828713 | 2473 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 2474 | } |
5c828713 | 2475 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
2476 | |
2477 | /** | |
2478 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
2479 | * @caller_jiffies: pointer to caller's state | |
2480 | * @interval_msecs: minimum interval between prints | |
2481 | * | |
2482 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
2483 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
2484 | * returned true. | |
2485 | */ | |
2486 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
2487 | unsigned int interval_msecs) | |
2488 | { | |
f2d28a2e GK |
2489 | if (*caller_jiffies == 0 |
2490 | || !time_in_range(jiffies, *caller_jiffies, | |
2491 | *caller_jiffies | |
2492 | + msecs_to_jiffies(interval_msecs))) { | |
2493 | *caller_jiffies = jiffies; | |
f46c4833 AM |
2494 | return true; |
2495 | } | |
2496 | return false; | |
2497 | } | |
2498 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
2499 | |
2500 | static DEFINE_SPINLOCK(dump_list_lock); | |
2501 | static LIST_HEAD(dump_list); | |
2502 | ||
2503 | /** | |
2504 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 2505 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
2506 | * |
2507 | * Adds a kernel log dumper to the system. The dump callback in the | |
2508 | * structure will be called when the kernel oopses or panics and must be | |
2509 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
2510 | */ | |
2511 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
2512 | { | |
2513 | unsigned long flags; | |
2514 | int err = -EBUSY; | |
2515 | ||
2516 | /* The dump callback needs to be set */ | |
2517 | if (!dumper->dump) | |
2518 | return -EINVAL; | |
2519 | ||
2520 | spin_lock_irqsave(&dump_list_lock, flags); | |
2521 | /* Don't allow registering multiple times */ | |
2522 | if (!dumper->registered) { | |
2523 | dumper->registered = 1; | |
fb842b00 | 2524 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
2525 | err = 0; |
2526 | } | |
2527 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
2528 | ||
2529 | return err; | |
2530 | } | |
2531 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
2532 | ||
2533 | /** | |
2534 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 2535 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
2536 | * |
2537 | * Removes a dump device from the system. Returns zero on success and | |
2538 | * %-EINVAL otherwise. | |
2539 | */ | |
2540 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
2541 | { | |
2542 | unsigned long flags; | |
2543 | int err = -EINVAL; | |
2544 | ||
2545 | spin_lock_irqsave(&dump_list_lock, flags); | |
2546 | if (dumper->registered) { | |
2547 | dumper->registered = 0; | |
fb842b00 | 2548 | list_del_rcu(&dumper->list); |
456b565c SK |
2549 | err = 0; |
2550 | } | |
2551 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 2552 | synchronize_rcu(); |
456b565c SK |
2553 | |
2554 | return err; | |
2555 | } | |
2556 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
2557 | ||
7ff9554b KS |
2558 | static bool always_kmsg_dump; |
2559 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); | |
2560 | ||
456b565c SK |
2561 | /** |
2562 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
2563 | * @reason: the reason (oops, panic etc) for dumping | |
2564 | * | |
e2ae715d KS |
2565 | * Call each of the registered dumper's dump() callback, which can |
2566 | * retrieve the kmsg records with kmsg_dump_get_line() or | |
2567 | * kmsg_dump_get_buffer(). | |
456b565c SK |
2568 | */ |
2569 | void kmsg_dump(enum kmsg_dump_reason reason) | |
2570 | { | |
456b565c | 2571 | struct kmsg_dumper *dumper; |
456b565c SK |
2572 | unsigned long flags; |
2573 | ||
c22ab332 MG |
2574 | if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump) |
2575 | return; | |
2576 | ||
e2ae715d KS |
2577 | rcu_read_lock(); |
2578 | list_for_each_entry_rcu(dumper, &dump_list, list) { | |
2579 | if (dumper->max_reason && reason > dumper->max_reason) | |
2580 | continue; | |
2581 | ||
2582 | /* initialize iterator with data about the stored records */ | |
2583 | dumper->active = true; | |
2584 | ||
2585 | raw_spin_lock_irqsave(&logbuf_lock, flags); | |
2586 | dumper->cur_seq = clear_seq; | |
2587 | dumper->cur_idx = clear_idx; | |
2588 | dumper->next_seq = log_next_seq; | |
2589 | dumper->next_idx = log_next_idx; | |
2590 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); | |
2591 | ||
2592 | /* invoke dumper which will iterate over records */ | |
2593 | dumper->dump(dumper, reason); | |
2594 | ||
2595 | /* reset iterator */ | |
2596 | dumper->active = false; | |
2597 | } | |
2598 | rcu_read_unlock(); | |
2599 | } | |
2600 | ||
2601 | /** | |
2602 | * kmsg_dump_get_line - retrieve one kmsg log line | |
2603 | * @dumper: registered kmsg dumper | |
2604 | * @syslog: include the "<4>" prefixes | |
2605 | * @line: buffer to copy the line to | |
2606 | * @size: maximum size of the buffer | |
2607 | * @len: length of line placed into buffer | |
2608 | * | |
2609 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
2610 | * record, and copy one record into the provided buffer. | |
2611 | * | |
2612 | * Consecutive calls will return the next available record moving | |
2613 | * towards the end of the buffer with the youngest messages. | |
2614 | * | |
2615 | * A return value of FALSE indicates that there are no more records to | |
2616 | * read. | |
2617 | */ | |
2618 | bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, | |
2619 | char *line, size_t size, size_t *len) | |
2620 | { | |
2621 | unsigned long flags; | |
2622 | struct log *msg; | |
2623 | size_t l = 0; | |
2624 | bool ret = false; | |
2625 | ||
2626 | if (!dumper->active) | |
2627 | goto out; | |
7ff9554b | 2628 | |
07354eb1 | 2629 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
e2ae715d KS |
2630 | if (dumper->cur_seq < log_first_seq) { |
2631 | /* messages are gone, move to first available one */ | |
2632 | dumper->cur_seq = log_first_seq; | |
2633 | dumper->cur_idx = log_first_idx; | |
2634 | } | |
456b565c | 2635 | |
e2ae715d KS |
2636 | /* last entry */ |
2637 | if (dumper->cur_seq >= log_next_seq) { | |
2638 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); | |
2639 | goto out; | |
2640 | } | |
456b565c | 2641 | |
e2ae715d | 2642 | msg = log_from_idx(dumper->cur_idx); |
5becfb1d | 2643 | l = msg_print_text(msg, 0, syslog, line, size); |
e2ae715d KS |
2644 | |
2645 | dumper->cur_idx = log_next(dumper->cur_idx); | |
2646 | dumper->cur_seq++; | |
2647 | ret = true; | |
2648 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); | |
2649 | out: | |
2650 | if (len) | |
2651 | *len = l; | |
2652 | return ret; | |
2653 | } | |
2654 | EXPORT_SYMBOL_GPL(kmsg_dump_get_line); | |
2655 | ||
2656 | /** | |
2657 | * kmsg_dump_get_buffer - copy kmsg log lines | |
2658 | * @dumper: registered kmsg dumper | |
2659 | * @syslog: include the "<4>" prefixes | |
4f0f4af5 | 2660 | * @buf: buffer to copy the line to |
e2ae715d KS |
2661 | * @size: maximum size of the buffer |
2662 | * @len: length of line placed into buffer | |
2663 | * | |
2664 | * Start at the end of the kmsg buffer and fill the provided buffer | |
2665 | * with as many of the the *youngest* kmsg records that fit into it. | |
2666 | * If the buffer is large enough, all available kmsg records will be | |
2667 | * copied with a single call. | |
2668 | * | |
2669 | * Consecutive calls will fill the buffer with the next block of | |
2670 | * available older records, not including the earlier retrieved ones. | |
2671 | * | |
2672 | * A return value of FALSE indicates that there are no more records to | |
2673 | * read. | |
2674 | */ | |
2675 | bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, | |
2676 | char *buf, size_t size, size_t *len) | |
2677 | { | |
2678 | unsigned long flags; | |
2679 | u64 seq; | |
2680 | u32 idx; | |
2681 | u64 next_seq; | |
2682 | u32 next_idx; | |
5becfb1d | 2683 | enum log_flags prev; |
e2ae715d KS |
2684 | size_t l = 0; |
2685 | bool ret = false; | |
2686 | ||
2687 | if (!dumper->active) | |
2688 | goto out; | |
2689 | ||
2690 | raw_spin_lock_irqsave(&logbuf_lock, flags); | |
2691 | if (dumper->cur_seq < log_first_seq) { | |
2692 | /* messages are gone, move to first available one */ | |
2693 | dumper->cur_seq = log_first_seq; | |
2694 | dumper->cur_idx = log_first_idx; | |
2695 | } | |
2696 | ||
2697 | /* last entry */ | |
2698 | if (dumper->cur_seq >= dumper->next_seq) { | |
2699 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); | |
2700 | goto out; | |
2701 | } | |
2702 | ||
2703 | /* calculate length of entire buffer */ | |
2704 | seq = dumper->cur_seq; | |
2705 | idx = dumper->cur_idx; | |
5becfb1d | 2706 | prev = 0; |
e2ae715d KS |
2707 | while (seq < dumper->next_seq) { |
2708 | struct log *msg = log_from_idx(idx); | |
2709 | ||
5becfb1d | 2710 | l += msg_print_text(msg, prev, true, NULL, 0); |
e2ae715d KS |
2711 | idx = log_next(idx); |
2712 | seq++; | |
5becfb1d | 2713 | prev = msg->flags; |
e2ae715d KS |
2714 | } |
2715 | ||
2716 | /* move first record forward until length fits into the buffer */ | |
2717 | seq = dumper->cur_seq; | |
2718 | idx = dumper->cur_idx; | |
5becfb1d | 2719 | prev = 0; |
e2ae715d KS |
2720 | while (l > size && seq < dumper->next_seq) { |
2721 | struct log *msg = log_from_idx(idx); | |
456b565c | 2722 | |
5becfb1d | 2723 | l -= msg_print_text(msg, prev, true, NULL, 0); |
e2ae715d KS |
2724 | idx = log_next(idx); |
2725 | seq++; | |
5becfb1d | 2726 | prev = msg->flags; |
456b565c | 2727 | } |
e2ae715d KS |
2728 | |
2729 | /* last message in next interation */ | |
2730 | next_seq = seq; | |
2731 | next_idx = idx; | |
2732 | ||
2733 | l = 0; | |
5becfb1d | 2734 | prev = 0; |
e2ae715d KS |
2735 | while (seq < dumper->next_seq) { |
2736 | struct log *msg = log_from_idx(idx); | |
2737 | ||
5becfb1d | 2738 | l += msg_print_text(msg, prev, syslog, buf + l, size - l); |
e2ae715d KS |
2739 | idx = log_next(idx); |
2740 | seq++; | |
5becfb1d | 2741 | prev = msg->flags; |
e2ae715d KS |
2742 | } |
2743 | ||
2744 | dumper->next_seq = next_seq; | |
2745 | dumper->next_idx = next_idx; | |
2746 | ret = true; | |
7ff9554b | 2747 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
e2ae715d KS |
2748 | out: |
2749 | if (len) | |
2750 | *len = l; | |
2751 | return ret; | |
2752 | } | |
2753 | EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); | |
456b565c | 2754 | |
e2ae715d KS |
2755 | /** |
2756 | * kmsg_dump_rewind - reset the interator | |
2757 | * @dumper: registered kmsg dumper | |
2758 | * | |
2759 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
2760 | * kmsg_dump_get_buffer() can be called again and used multiple | |
2761 | * times within the same dumper.dump() callback. | |
2762 | */ | |
2763 | void kmsg_dump_rewind(struct kmsg_dumper *dumper) | |
2764 | { | |
2765 | unsigned long flags; | |
2766 | ||
2767 | raw_spin_lock_irqsave(&logbuf_lock, flags); | |
2768 | dumper->cur_seq = clear_seq; | |
2769 | dumper->cur_idx = clear_idx; | |
2770 | dumper->next_seq = log_next_seq; | |
2771 | dumper->next_idx = log_next_idx; | |
2772 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); | |
456b565c | 2773 | } |
e2ae715d | 2774 | EXPORT_SYMBOL_GPL(kmsg_dump_rewind); |
7ef3d2fd | 2775 | #endif |