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1da177e4 LT |
1 | /* |
2 | * linux/kernel/printk.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * Modified to make sys_syslog() more flexible: added commands to | |
7 | * return the last 4k of kernel messages, regardless of whether | |
8 | * they've been read or not. Added option to suppress kernel printk's | |
9 | * to the console. Added hook for sending the console messages | |
10 | * elsewhere, in preparation for a serial line console (someday). | |
11 | * Ted Ts'o, 2/11/93. | |
12 | * Modified for sysctl support, 1/8/97, Chris Horn. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 | 15 | * Rewrote bits to get rid of console_lock |
e1f8e874 | 16 | * 01Mar01 Andrew Morton |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
1da177e4 LT |
23 | #include <linux/console.h> |
24 | #include <linux/init.h> | |
bfe8df3d RD |
25 | #include <linux/jiffies.h> |
26 | #include <linux/nmi.h> | |
1da177e4 | 27 | #include <linux/module.h> |
3b9c0410 | 28 | #include <linux/moduleparam.h> |
1da177e4 | 29 | #include <linux/interrupt.h> /* For in_interrupt() */ |
1da177e4 LT |
30 | #include <linux/delay.h> |
31 | #include <linux/smp.h> | |
32 | #include <linux/security.h> | |
33 | #include <linux/bootmem.h> | |
162a7e75 | 34 | #include <linux/memblock.h> |
a27bb332 | 35 | #include <linux/aio.h> |
1da177e4 | 36 | #include <linux/syscalls.h> |
04d491ab | 37 | #include <linux/kexec.h> |
d37d39ae | 38 | #include <linux/kdb.h> |
3fff4c42 | 39 | #include <linux/ratelimit.h> |
456b565c | 40 | #include <linux/kmsg_dump.h> |
00234592 | 41 | #include <linux/syslog.h> |
034260d6 KC |
42 | #include <linux/cpu.h> |
43 | #include <linux/notifier.h> | |
fb842b00 | 44 | #include <linux/rculist.h> |
e11fea92 | 45 | #include <linux/poll.h> |
74876a98 | 46 | #include <linux/irq_work.h> |
196779b9 | 47 | #include <linux/utsname.h> |
249771b8 | 48 | #include <linux/ctype.h> |
1da177e4 LT |
49 | |
50 | #include <asm/uaccess.h> | |
51 | ||
95100358 JB |
52 | #define CREATE_TRACE_POINTS |
53 | #include <trace/events/printk.h> | |
54 | ||
d197c43d | 55 | #include "console_cmdline.h" |
bbeddf52 | 56 | #include "braille.h" |
d197c43d | 57 | |
1da177e4 | 58 | int console_printk[4] = { |
a8fe19eb | 59 | CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */ |
42a9dc0b | 60 | MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */ |
a8fe19eb BP |
61 | CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */ |
62 | CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ | |
1da177e4 LT |
63 | }; |
64 | ||
1da177e4 | 65 | /* |
0bbfb7c2 | 66 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
67 | * their unblank() callback or not. So let's export it. |
68 | */ | |
69 | int oops_in_progress; | |
70 | EXPORT_SYMBOL(oops_in_progress); | |
71 | ||
72 | /* | |
73 | * console_sem protects the console_drivers list, and also | |
74 | * provides serialisation for access to the entire console | |
75 | * driver system. | |
76 | */ | |
5b8c4f23 | 77 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 78 | struct console *console_drivers; |
a29d1cfe IM |
79 | EXPORT_SYMBOL_GPL(console_drivers); |
80 | ||
daee7797 DV |
81 | #ifdef CONFIG_LOCKDEP |
82 | static struct lockdep_map console_lock_dep_map = { | |
83 | .name = "console_lock" | |
84 | }; | |
85 | #endif | |
86 | ||
bd8d7cf5 JK |
87 | /* |
88 | * Helper macros to handle lockdep when locking/unlocking console_sem. We use | |
89 | * macros instead of functions so that _RET_IP_ contains useful information. | |
90 | */ | |
91 | #define down_console_sem() do { \ | |
92 | down(&console_sem);\ | |
93 | mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ | |
94 | } while (0) | |
95 | ||
96 | static int __down_trylock_console_sem(unsigned long ip) | |
97 | { | |
98 | if (down_trylock(&console_sem)) | |
99 | return 1; | |
100 | mutex_acquire(&console_lock_dep_map, 0, 1, ip); | |
101 | return 0; | |
102 | } | |
103 | #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) | |
104 | ||
105 | #define up_console_sem() do { \ | |
106 | mutex_release(&console_lock_dep_map, 1, _RET_IP_);\ | |
107 | up(&console_sem);\ | |
108 | } while (0) | |
109 | ||
1da177e4 LT |
110 | /* |
111 | * This is used for debugging the mess that is the VT code by | |
112 | * keeping track if we have the console semaphore held. It's | |
113 | * definitely not the perfect debug tool (we don't know if _WE_ | |
0b90fec3 AE |
114 | * hold it and are racing, but it helps tracking those weird code |
115 | * paths in the console code where we end up in places I want | |
116 | * locked without the console sempahore held). | |
1da177e4 | 117 | */ |
557240b4 | 118 | static int console_locked, console_suspended; |
1da177e4 | 119 | |
fe3d8ad3 FT |
120 | /* |
121 | * If exclusive_console is non-NULL then only this console is to be printed to. | |
122 | */ | |
123 | static struct console *exclusive_console; | |
124 | ||
1da177e4 LT |
125 | /* |
126 | * Array of consoles built from command line options (console=) | |
127 | */ | |
1da177e4 LT |
128 | |
129 | #define MAX_CMDLINECONSOLES 8 | |
130 | ||
131 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
d197c43d | 132 | |
1da177e4 LT |
133 | static int selected_console = -1; |
134 | static int preferred_console = -1; | |
9e124fe1 MA |
135 | int console_set_on_cmdline; |
136 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
137 | |
138 | /* Flag: console code may call schedule() */ | |
139 | static int console_may_schedule; | |
140 | ||
7ff9554b KS |
141 | /* |
142 | * The printk log buffer consists of a chain of concatenated variable | |
143 | * length records. Every record starts with a record header, containing | |
144 | * the overall length of the record. | |
145 | * | |
146 | * The heads to the first and last entry in the buffer, as well as the | |
0b90fec3 AE |
147 | * sequence numbers of these entries are maintained when messages are |
148 | * stored. | |
7ff9554b KS |
149 | * |
150 | * If the heads indicate available messages, the length in the header | |
151 | * tells the start next message. A length == 0 for the next message | |
152 | * indicates a wrap-around to the beginning of the buffer. | |
153 | * | |
154 | * Every record carries the monotonic timestamp in microseconds, as well as | |
155 | * the standard userspace syslog level and syslog facility. The usual | |
156 | * kernel messages use LOG_KERN; userspace-injected messages always carry | |
157 | * a matching syslog facility, by default LOG_USER. The origin of every | |
158 | * message can be reliably determined that way. | |
159 | * | |
160 | * The human readable log message directly follows the message header. The | |
161 | * length of the message text is stored in the header, the stored message | |
162 | * is not terminated. | |
163 | * | |
e11fea92 KS |
164 | * Optionally, a message can carry a dictionary of properties (key/value pairs), |
165 | * to provide userspace with a machine-readable message context. | |
166 | * | |
167 | * Examples for well-defined, commonly used property names are: | |
168 | * DEVICE=b12:8 device identifier | |
169 | * b12:8 block dev_t | |
170 | * c127:3 char dev_t | |
171 | * n8 netdev ifindex | |
172 | * +sound:card0 subsystem:devname | |
173 | * SUBSYSTEM=pci driver-core subsystem name | |
174 | * | |
175 | * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value | |
176 | * follows directly after a '=' character. Every property is terminated by | |
177 | * a '\0' character. The last property is not terminated. | |
178 | * | |
179 | * Example of a message structure: | |
180 | * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec | |
181 | * 0008 34 00 record is 52 bytes long | |
182 | * 000a 0b 00 text is 11 bytes long | |
183 | * 000c 1f 00 dictionary is 23 bytes long | |
184 | * 000e 03 00 LOG_KERN (facility) LOG_ERR (level) | |
185 | * 0010 69 74 27 73 20 61 20 6c "it's a l" | |
186 | * 69 6e 65 "ine" | |
187 | * 001b 44 45 56 49 43 "DEVIC" | |
188 | * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D" | |
189 | * 52 49 56 45 52 3d 62 75 "RIVER=bu" | |
190 | * 67 "g" | |
191 | * 0032 00 00 00 padding to next message header | |
192 | * | |
62e32ac3 | 193 | * The 'struct printk_log' buffer header must never be directly exported to |
e11fea92 KS |
194 | * userspace, it is a kernel-private implementation detail that might |
195 | * need to be changed in the future, when the requirements change. | |
196 | * | |
197 | * /dev/kmsg exports the structured data in the following line format: | |
198 | * "level,sequnum,timestamp;<message text>\n" | |
199 | * | |
200 | * The optional key/value pairs are attached as continuation lines starting | |
201 | * with a space character and terminated by a newline. All possible | |
202 | * non-prinatable characters are escaped in the "\xff" notation. | |
203 | * | |
204 | * Users of the export format should ignore possible additional values | |
205 | * separated by ',', and find the message after the ';' character. | |
7ff9554b KS |
206 | */ |
207 | ||
084681d1 | 208 | enum log_flags { |
5becfb1d KS |
209 | LOG_NOCONS = 1, /* already flushed, do not print to console */ |
210 | LOG_NEWLINE = 2, /* text ended with a newline */ | |
211 | LOG_PREFIX = 4, /* text started with a prefix */ | |
212 | LOG_CONT = 8, /* text is a fragment of a continuation line */ | |
084681d1 KS |
213 | }; |
214 | ||
62e32ac3 | 215 | struct printk_log { |
7ff9554b KS |
216 | u64 ts_nsec; /* timestamp in nanoseconds */ |
217 | u16 len; /* length of entire record */ | |
218 | u16 text_len; /* length of text buffer */ | |
219 | u16 dict_len; /* length of dictionary buffer */ | |
084681d1 KS |
220 | u8 facility; /* syslog facility */ |
221 | u8 flags:5; /* internal record flags */ | |
222 | u8 level:3; /* syslog level */ | |
7ff9554b KS |
223 | }; |
224 | ||
225 | /* | |
458df9fd SR |
226 | * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken |
227 | * within the scheduler's rq lock. It must be released before calling | |
228 | * console_unlock() or anything else that might wake up a process. | |
7ff9554b KS |
229 | */ |
230 | static DEFINE_RAW_SPINLOCK(logbuf_lock); | |
d59745ce | 231 | |
96efedf1 | 232 | #ifdef CONFIG_PRINTK |
dc72c32e | 233 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
7f3a781d KS |
234 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
235 | static u64 syslog_seq; | |
236 | static u32 syslog_idx; | |
5becfb1d | 237 | static enum log_flags syslog_prev; |
eb02dac9 | 238 | static size_t syslog_partial; |
7ff9554b KS |
239 | |
240 | /* index and sequence number of the first record stored in the buffer */ | |
241 | static u64 log_first_seq; | |
242 | static u32 log_first_idx; | |
243 | ||
244 | /* index and sequence number of the next record to store in the buffer */ | |
245 | static u64 log_next_seq; | |
246 | static u32 log_next_idx; | |
247 | ||
eab07260 KS |
248 | /* the next printk record to write to the console */ |
249 | static u64 console_seq; | |
250 | static u32 console_idx; | |
251 | static enum log_flags console_prev; | |
252 | ||
7ff9554b KS |
253 | /* the next printk record to read after the last 'clear' command */ |
254 | static u64 clear_seq; | |
255 | static u32 clear_idx; | |
256 | ||
70498253 | 257 | #define PREFIX_MAX 32 |
249771b8 | 258 | #define LOG_LINE_MAX (1024 - PREFIX_MAX) |
7f3a781d KS |
259 | |
260 | /* record buffer */ | |
6ebb017d | 261 | #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) |
f8450fca SW |
262 | #define LOG_ALIGN 4 |
263 | #else | |
62e32ac3 | 264 | #define LOG_ALIGN __alignof__(struct printk_log) |
f8450fca | 265 | #endif |
7f3a781d | 266 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
f8450fca | 267 | static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); |
7f3a781d KS |
268 | static char *log_buf = __log_buf; |
269 | static u32 log_buf_len = __LOG_BUF_LEN; | |
270 | ||
14c4000a VH |
271 | /* Return log buffer address */ |
272 | char *log_buf_addr_get(void) | |
273 | { | |
274 | return log_buf; | |
275 | } | |
276 | ||
277 | /* Return log buffer size */ | |
278 | u32 log_buf_len_get(void) | |
279 | { | |
280 | return log_buf_len; | |
281 | } | |
282 | ||
7ff9554b | 283 | /* human readable text of the record */ |
62e32ac3 | 284 | static char *log_text(const struct printk_log *msg) |
7ff9554b | 285 | { |
62e32ac3 | 286 | return (char *)msg + sizeof(struct printk_log); |
7ff9554b KS |
287 | } |
288 | ||
289 | /* optional key/value pair dictionary attached to the record */ | |
62e32ac3 | 290 | static char *log_dict(const struct printk_log *msg) |
7ff9554b | 291 | { |
62e32ac3 | 292 | return (char *)msg + sizeof(struct printk_log) + msg->text_len; |
7ff9554b KS |
293 | } |
294 | ||
295 | /* get record by index; idx must point to valid msg */ | |
62e32ac3 | 296 | static struct printk_log *log_from_idx(u32 idx) |
7ff9554b | 297 | { |
62e32ac3 | 298 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); |
7ff9554b KS |
299 | |
300 | /* | |
301 | * A length == 0 record is the end of buffer marker. Wrap around and | |
302 | * read the message at the start of the buffer. | |
303 | */ | |
304 | if (!msg->len) | |
62e32ac3 | 305 | return (struct printk_log *)log_buf; |
7ff9554b KS |
306 | return msg; |
307 | } | |
308 | ||
309 | /* get next record; idx must point to valid msg */ | |
310 | static u32 log_next(u32 idx) | |
311 | { | |
62e32ac3 | 312 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); |
7ff9554b KS |
313 | |
314 | /* length == 0 indicates the end of the buffer; wrap */ | |
315 | /* | |
316 | * A length == 0 record is the end of buffer marker. Wrap around and | |
317 | * read the message at the start of the buffer as *this* one, and | |
318 | * return the one after that. | |
319 | */ | |
320 | if (!msg->len) { | |
62e32ac3 | 321 | msg = (struct printk_log *)log_buf; |
7ff9554b KS |
322 | return msg->len; |
323 | } | |
324 | return idx + msg->len; | |
325 | } | |
326 | ||
f40e4b9f PM |
327 | /* |
328 | * Check whether there is enough free space for the given message. | |
329 | * | |
330 | * The same values of first_idx and next_idx mean that the buffer | |
331 | * is either empty or full. | |
332 | * | |
333 | * If the buffer is empty, we must respect the position of the indexes. | |
334 | * They cannot be reset to the beginning of the buffer. | |
335 | */ | |
336 | static int logbuf_has_space(u32 msg_size, bool empty) | |
0a581694 PM |
337 | { |
338 | u32 free; | |
339 | ||
f40e4b9f | 340 | if (log_next_idx > log_first_idx || empty) |
0a581694 PM |
341 | free = max(log_buf_len - log_next_idx, log_first_idx); |
342 | else | |
343 | free = log_first_idx - log_next_idx; | |
344 | ||
345 | /* | |
346 | * We need space also for an empty header that signalizes wrapping | |
347 | * of the buffer. | |
348 | */ | |
349 | return free >= msg_size + sizeof(struct printk_log); | |
350 | } | |
351 | ||
f40e4b9f | 352 | static int log_make_free_space(u32 msg_size) |
0a581694 PM |
353 | { |
354 | while (log_first_seq < log_next_seq) { | |
f40e4b9f PM |
355 | if (logbuf_has_space(msg_size, false)) |
356 | return 0; | |
0b90fec3 | 357 | /* drop old messages until we have enough contiguous space */ |
0a581694 PM |
358 | log_first_idx = log_next(log_first_idx); |
359 | log_first_seq++; | |
360 | } | |
f40e4b9f PM |
361 | |
362 | /* sequence numbers are equal, so the log buffer is empty */ | |
363 | if (logbuf_has_space(msg_size, true)) | |
364 | return 0; | |
365 | ||
366 | return -ENOMEM; | |
0a581694 PM |
367 | } |
368 | ||
85c87043 PM |
369 | /* compute the message size including the padding bytes */ |
370 | static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len) | |
371 | { | |
372 | u32 size; | |
373 | ||
374 | size = sizeof(struct printk_log) + text_len + dict_len; | |
375 | *pad_len = (-size) & (LOG_ALIGN - 1); | |
376 | size += *pad_len; | |
377 | ||
378 | return size; | |
379 | } | |
380 | ||
55bd53a4 PM |
381 | /* |
382 | * Define how much of the log buffer we could take at maximum. The value | |
383 | * must be greater than two. Note that only half of the buffer is available | |
384 | * when the index points to the middle. | |
385 | */ | |
386 | #define MAX_LOG_TAKE_PART 4 | |
387 | static const char trunc_msg[] = "<truncated>"; | |
388 | ||
389 | static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len, | |
390 | u16 *dict_len, u32 *pad_len) | |
391 | { | |
392 | /* | |
393 | * The message should not take the whole buffer. Otherwise, it might | |
394 | * get removed too soon. | |
395 | */ | |
396 | u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART; | |
397 | if (*text_len > max_text_len) | |
398 | *text_len = max_text_len; | |
399 | /* enable the warning message */ | |
400 | *trunc_msg_len = strlen(trunc_msg); | |
401 | /* disable the "dict" completely */ | |
402 | *dict_len = 0; | |
403 | /* compute the size again, count also the warning message */ | |
404 | return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len); | |
405 | } | |
406 | ||
7ff9554b | 407 | /* insert record into the buffer, discard old ones, update heads */ |
034633cc PM |
408 | static int log_store(int facility, int level, |
409 | enum log_flags flags, u64 ts_nsec, | |
410 | const char *dict, u16 dict_len, | |
411 | const char *text, u16 text_len) | |
7ff9554b | 412 | { |
62e32ac3 | 413 | struct printk_log *msg; |
7ff9554b | 414 | u32 size, pad_len; |
55bd53a4 | 415 | u16 trunc_msg_len = 0; |
7ff9554b KS |
416 | |
417 | /* number of '\0' padding bytes to next message */ | |
85c87043 | 418 | size = msg_used_size(text_len, dict_len, &pad_len); |
7ff9554b | 419 | |
55bd53a4 PM |
420 | if (log_make_free_space(size)) { |
421 | /* truncate the message if it is too long for empty buffer */ | |
422 | size = truncate_msg(&text_len, &trunc_msg_len, | |
423 | &dict_len, &pad_len); | |
424 | /* survive when the log buffer is too small for trunc_msg */ | |
425 | if (log_make_free_space(size)) | |
034633cc | 426 | return 0; |
55bd53a4 | 427 | } |
7ff9554b | 428 | |
39b25109 | 429 | if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) { |
7ff9554b KS |
430 | /* |
431 | * This message + an additional empty header does not fit | |
432 | * at the end of the buffer. Add an empty header with len == 0 | |
433 | * to signify a wrap around. | |
434 | */ | |
62e32ac3 | 435 | memset(log_buf + log_next_idx, 0, sizeof(struct printk_log)); |
7ff9554b KS |
436 | log_next_idx = 0; |
437 | } | |
438 | ||
439 | /* fill message */ | |
62e32ac3 | 440 | msg = (struct printk_log *)(log_buf + log_next_idx); |
7ff9554b KS |
441 | memcpy(log_text(msg), text, text_len); |
442 | msg->text_len = text_len; | |
55bd53a4 PM |
443 | if (trunc_msg_len) { |
444 | memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len); | |
445 | msg->text_len += trunc_msg_len; | |
446 | } | |
7ff9554b KS |
447 | memcpy(log_dict(msg), dict, dict_len); |
448 | msg->dict_len = dict_len; | |
084681d1 KS |
449 | msg->facility = facility; |
450 | msg->level = level & 7; | |
451 | msg->flags = flags & 0x1f; | |
452 | if (ts_nsec > 0) | |
453 | msg->ts_nsec = ts_nsec; | |
454 | else | |
455 | msg->ts_nsec = local_clock(); | |
7ff9554b | 456 | memset(log_dict(msg) + dict_len, 0, pad_len); |
fce6e033 | 457 | msg->len = size; |
7ff9554b KS |
458 | |
459 | /* insert message */ | |
460 | log_next_idx += msg->len; | |
461 | log_next_seq++; | |
034633cc PM |
462 | |
463 | return msg->text_len; | |
7ff9554b | 464 | } |
d59745ce | 465 | |
e99aa461 | 466 | int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); |
637241a9 KC |
467 | |
468 | static int syslog_action_restricted(int type) | |
469 | { | |
470 | if (dmesg_restrict) | |
471 | return 1; | |
472 | /* | |
473 | * Unless restricted, we allow "read all" and "get buffer size" | |
474 | * for everybody. | |
475 | */ | |
476 | return type != SYSLOG_ACTION_READ_ALL && | |
477 | type != SYSLOG_ACTION_SIZE_BUFFER; | |
478 | } | |
479 | ||
68c4a4f8 | 480 | int check_syslog_permissions(int type, bool from_file) |
637241a9 KC |
481 | { |
482 | /* | |
483 | * If this is from /proc/kmsg and we've already opened it, then we've | |
484 | * already done the capabilities checks at open time. | |
485 | */ | |
486 | if (from_file && type != SYSLOG_ACTION_OPEN) | |
487 | return 0; | |
488 | ||
489 | if (syslog_action_restricted(type)) { | |
490 | if (capable(CAP_SYSLOG)) | |
491 | return 0; | |
492 | /* | |
493 | * For historical reasons, accept CAP_SYS_ADMIN too, with | |
494 | * a warning. | |
495 | */ | |
496 | if (capable(CAP_SYS_ADMIN)) { | |
497 | pr_warn_once("%s (%d): Attempt to access syslog with " | |
498 | "CAP_SYS_ADMIN but no CAP_SYSLOG " | |
499 | "(deprecated).\n", | |
500 | current->comm, task_pid_nr(current)); | |
501 | return 0; | |
502 | } | |
503 | return -EPERM; | |
504 | } | |
505 | return security_syslog(type); | |
506 | } | |
507 | ||
508 | ||
e11fea92 KS |
509 | /* /dev/kmsg - userspace message inject/listen interface */ |
510 | struct devkmsg_user { | |
511 | u64 seq; | |
512 | u32 idx; | |
d39f3d77 | 513 | enum log_flags prev; |
e11fea92 KS |
514 | struct mutex lock; |
515 | char buf[8192]; | |
516 | }; | |
517 | ||
849f3127 | 518 | static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from) |
e11fea92 KS |
519 | { |
520 | char *buf, *line; | |
521 | int i; | |
522 | int level = default_message_loglevel; | |
523 | int facility = 1; /* LOG_USER */ | |
849f3127 | 524 | size_t len = iocb->ki_nbytes; |
e11fea92 KS |
525 | ssize_t ret = len; |
526 | ||
527 | if (len > LOG_LINE_MAX) | |
528 | return -EINVAL; | |
529 | buf = kmalloc(len+1, GFP_KERNEL); | |
530 | if (buf == NULL) | |
531 | return -ENOMEM; | |
532 | ||
849f3127 AV |
533 | buf[len] = '\0'; |
534 | if (copy_from_iter(buf, len, from) != len) { | |
535 | kfree(buf); | |
536 | return -EFAULT; | |
e11fea92 KS |
537 | } |
538 | ||
539 | /* | |
540 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace | |
541 | * the decimal value represents 32bit, the lower 3 bit are the log | |
542 | * level, the rest are the log facility. | |
543 | * | |
544 | * If no prefix or no userspace facility is specified, we | |
545 | * enforce LOG_USER, to be able to reliably distinguish | |
546 | * kernel-generated messages from userspace-injected ones. | |
547 | */ | |
548 | line = buf; | |
549 | if (line[0] == '<') { | |
550 | char *endp = NULL; | |
551 | ||
552 | i = simple_strtoul(line+1, &endp, 10); | |
553 | if (endp && endp[0] == '>') { | |
554 | level = i & 7; | |
555 | if (i >> 3) | |
556 | facility = i >> 3; | |
557 | endp++; | |
558 | len -= endp - line; | |
559 | line = endp; | |
560 | } | |
561 | } | |
e11fea92 KS |
562 | |
563 | printk_emit(facility, level, NULL, 0, "%s", line); | |
e11fea92 KS |
564 | kfree(buf); |
565 | return ret; | |
566 | } | |
567 | ||
568 | static ssize_t devkmsg_read(struct file *file, char __user *buf, | |
569 | size_t count, loff_t *ppos) | |
570 | { | |
571 | struct devkmsg_user *user = file->private_data; | |
62e32ac3 | 572 | struct printk_log *msg; |
5fc32490 | 573 | u64 ts_usec; |
e11fea92 | 574 | size_t i; |
d39f3d77 | 575 | char cont = '-'; |
e11fea92 KS |
576 | size_t len; |
577 | ssize_t ret; | |
578 | ||
579 | if (!user) | |
580 | return -EBADF; | |
581 | ||
4a77a5a0 YL |
582 | ret = mutex_lock_interruptible(&user->lock); |
583 | if (ret) | |
584 | return ret; | |
5c53d819 | 585 | raw_spin_lock_irq(&logbuf_lock); |
e11fea92 KS |
586 | while (user->seq == log_next_seq) { |
587 | if (file->f_flags & O_NONBLOCK) { | |
588 | ret = -EAGAIN; | |
5c53d819 | 589 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
590 | goto out; |
591 | } | |
592 | ||
5c53d819 | 593 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
594 | ret = wait_event_interruptible(log_wait, |
595 | user->seq != log_next_seq); | |
596 | if (ret) | |
597 | goto out; | |
5c53d819 | 598 | raw_spin_lock_irq(&logbuf_lock); |
e11fea92 KS |
599 | } |
600 | ||
601 | if (user->seq < log_first_seq) { | |
602 | /* our last seen message is gone, return error and reset */ | |
603 | user->idx = log_first_idx; | |
604 | user->seq = log_first_seq; | |
605 | ret = -EPIPE; | |
5c53d819 | 606 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
607 | goto out; |
608 | } | |
609 | ||
610 | msg = log_from_idx(user->idx); | |
5fc32490 KS |
611 | ts_usec = msg->ts_nsec; |
612 | do_div(ts_usec, 1000); | |
d39f3d77 KS |
613 | |
614 | /* | |
615 | * If we couldn't merge continuation line fragments during the print, | |
616 | * export the stored flags to allow an optional external merge of the | |
617 | * records. Merging the records isn't always neccessarily correct, like | |
618 | * when we hit a race during printing. In most cases though, it produces | |
619 | * better readable output. 'c' in the record flags mark the first | |
620 | * fragment of a line, '+' the following. | |
621 | */ | |
622 | if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT)) | |
623 | cont = 'c'; | |
624 | else if ((msg->flags & LOG_CONT) || | |
625 | ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))) | |
626 | cont = '+'; | |
627 | ||
628 | len = sprintf(user->buf, "%u,%llu,%llu,%c;", | |
629 | (msg->facility << 3) | msg->level, | |
630 | user->seq, ts_usec, cont); | |
631 | user->prev = msg->flags; | |
e11fea92 KS |
632 | |
633 | /* escape non-printable characters */ | |
634 | for (i = 0; i < msg->text_len; i++) { | |
3ce9a7c0 | 635 | unsigned char c = log_text(msg)[i]; |
e11fea92 | 636 | |
e3f5a5f2 | 637 | if (c < ' ' || c >= 127 || c == '\\') |
e11fea92 KS |
638 | len += sprintf(user->buf + len, "\\x%02x", c); |
639 | else | |
640 | user->buf[len++] = c; | |
641 | } | |
642 | user->buf[len++] = '\n'; | |
643 | ||
644 | if (msg->dict_len) { | |
645 | bool line = true; | |
646 | ||
647 | for (i = 0; i < msg->dict_len; i++) { | |
3ce9a7c0 | 648 | unsigned char c = log_dict(msg)[i]; |
e11fea92 KS |
649 | |
650 | if (line) { | |
651 | user->buf[len++] = ' '; | |
652 | line = false; | |
653 | } | |
654 | ||
655 | if (c == '\0') { | |
656 | user->buf[len++] = '\n'; | |
657 | line = true; | |
658 | continue; | |
659 | } | |
660 | ||
e3f5a5f2 | 661 | if (c < ' ' || c >= 127 || c == '\\') { |
e11fea92 KS |
662 | len += sprintf(user->buf + len, "\\x%02x", c); |
663 | continue; | |
664 | } | |
665 | ||
666 | user->buf[len++] = c; | |
667 | } | |
668 | user->buf[len++] = '\n'; | |
669 | } | |
670 | ||
671 | user->idx = log_next(user->idx); | |
672 | user->seq++; | |
5c53d819 | 673 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
674 | |
675 | if (len > count) { | |
676 | ret = -EINVAL; | |
677 | goto out; | |
678 | } | |
679 | ||
680 | if (copy_to_user(buf, user->buf, len)) { | |
681 | ret = -EFAULT; | |
682 | goto out; | |
683 | } | |
684 | ret = len; | |
685 | out: | |
686 | mutex_unlock(&user->lock); | |
687 | return ret; | |
688 | } | |
689 | ||
690 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) | |
691 | { | |
692 | struct devkmsg_user *user = file->private_data; | |
693 | loff_t ret = 0; | |
694 | ||
695 | if (!user) | |
696 | return -EBADF; | |
697 | if (offset) | |
698 | return -ESPIPE; | |
699 | ||
5c53d819 | 700 | raw_spin_lock_irq(&logbuf_lock); |
e11fea92 KS |
701 | switch (whence) { |
702 | case SEEK_SET: | |
703 | /* the first record */ | |
704 | user->idx = log_first_idx; | |
705 | user->seq = log_first_seq; | |
706 | break; | |
707 | case SEEK_DATA: | |
708 | /* | |
709 | * The first record after the last SYSLOG_ACTION_CLEAR, | |
710 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself | |
711 | * changes no global state, and does not clear anything. | |
712 | */ | |
713 | user->idx = clear_idx; | |
714 | user->seq = clear_seq; | |
715 | break; | |
716 | case SEEK_END: | |
717 | /* after the last record */ | |
718 | user->idx = log_next_idx; | |
719 | user->seq = log_next_seq; | |
720 | break; | |
721 | default: | |
722 | ret = -EINVAL; | |
723 | } | |
5c53d819 | 724 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
725 | return ret; |
726 | } | |
727 | ||
728 | static unsigned int devkmsg_poll(struct file *file, poll_table *wait) | |
729 | { | |
730 | struct devkmsg_user *user = file->private_data; | |
731 | int ret = 0; | |
732 | ||
733 | if (!user) | |
734 | return POLLERR|POLLNVAL; | |
735 | ||
736 | poll_wait(file, &log_wait, wait); | |
737 | ||
5c53d819 | 738 | raw_spin_lock_irq(&logbuf_lock); |
e11fea92 KS |
739 | if (user->seq < log_next_seq) { |
740 | /* return error when data has vanished underneath us */ | |
741 | if (user->seq < log_first_seq) | |
742 | ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI; | |
0a285317 NK |
743 | else |
744 | ret = POLLIN|POLLRDNORM; | |
e11fea92 | 745 | } |
5c53d819 | 746 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
747 | |
748 | return ret; | |
749 | } | |
750 | ||
751 | static int devkmsg_open(struct inode *inode, struct file *file) | |
752 | { | |
753 | struct devkmsg_user *user; | |
754 | int err; | |
755 | ||
756 | /* write-only does not need any file context */ | |
757 | if ((file->f_flags & O_ACCMODE) == O_WRONLY) | |
758 | return 0; | |
759 | ||
637241a9 KC |
760 | err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, |
761 | SYSLOG_FROM_READER); | |
e11fea92 KS |
762 | if (err) |
763 | return err; | |
764 | ||
765 | user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); | |
766 | if (!user) | |
767 | return -ENOMEM; | |
768 | ||
769 | mutex_init(&user->lock); | |
770 | ||
5c53d819 | 771 | raw_spin_lock_irq(&logbuf_lock); |
e11fea92 KS |
772 | user->idx = log_first_idx; |
773 | user->seq = log_first_seq; | |
5c53d819 | 774 | raw_spin_unlock_irq(&logbuf_lock); |
e11fea92 KS |
775 | |
776 | file->private_data = user; | |
777 | return 0; | |
778 | } | |
779 | ||
780 | static int devkmsg_release(struct inode *inode, struct file *file) | |
781 | { | |
782 | struct devkmsg_user *user = file->private_data; | |
783 | ||
784 | if (!user) | |
785 | return 0; | |
786 | ||
787 | mutex_destroy(&user->lock); | |
788 | kfree(user); | |
789 | return 0; | |
790 | } | |
791 | ||
792 | const struct file_operations kmsg_fops = { | |
793 | .open = devkmsg_open, | |
794 | .read = devkmsg_read, | |
849f3127 | 795 | .write_iter = devkmsg_write, |
e11fea92 KS |
796 | .llseek = devkmsg_llseek, |
797 | .poll = devkmsg_poll, | |
798 | .release = devkmsg_release, | |
799 | }; | |
800 | ||
04d491ab NH |
801 | #ifdef CONFIG_KEXEC |
802 | /* | |
4c1ace64 | 803 | * This appends the listed symbols to /proc/vmcore |
04d491ab | 804 | * |
4c1ace64 | 805 | * /proc/vmcore is used by various utilities, like crash and makedumpfile to |
04d491ab NH |
806 | * obtain access to symbols that are otherwise very difficult to locate. These |
807 | * symbols are specifically used so that utilities can access and extract the | |
808 | * dmesg log from a vmcore file after a crash. | |
809 | */ | |
810 | void log_buf_kexec_setup(void) | |
811 | { | |
812 | VMCOREINFO_SYMBOL(log_buf); | |
04d491ab | 813 | VMCOREINFO_SYMBOL(log_buf_len); |
7ff9554b KS |
814 | VMCOREINFO_SYMBOL(log_first_idx); |
815 | VMCOREINFO_SYMBOL(log_next_idx); | |
6791457a | 816 | /* |
62e32ac3 | 817 | * Export struct printk_log size and field offsets. User space tools can |
6791457a VG |
818 | * parse it and detect any changes to structure down the line. |
819 | */ | |
62e32ac3 JP |
820 | VMCOREINFO_STRUCT_SIZE(printk_log); |
821 | VMCOREINFO_OFFSET(printk_log, ts_nsec); | |
822 | VMCOREINFO_OFFSET(printk_log, len); | |
823 | VMCOREINFO_OFFSET(printk_log, text_len); | |
824 | VMCOREINFO_OFFSET(printk_log, dict_len); | |
04d491ab NH |
825 | } |
826 | #endif | |
827 | ||
162a7e75 MT |
828 | /* requested log_buf_len from kernel cmdline */ |
829 | static unsigned long __initdata new_log_buf_len; | |
830 | ||
c0a318a3 LR |
831 | /* we practice scaling the ring buffer by powers of 2 */ |
832 | static void __init log_buf_len_update(unsigned size) | |
1da177e4 | 833 | { |
1da177e4 LT |
834 | if (size) |
835 | size = roundup_pow_of_two(size); | |
162a7e75 MT |
836 | if (size > log_buf_len) |
837 | new_log_buf_len = size; | |
c0a318a3 LR |
838 | } |
839 | ||
840 | /* save requested log_buf_len since it's too early to process it */ | |
841 | static int __init log_buf_len_setup(char *str) | |
842 | { | |
843 | unsigned size = memparse(str, &str); | |
844 | ||
845 | log_buf_len_update(size); | |
162a7e75 MT |
846 | |
847 | return 0; | |
1da177e4 | 848 | } |
162a7e75 MT |
849 | early_param("log_buf_len", log_buf_len_setup); |
850 | ||
2240a31d GU |
851 | #ifdef CONFIG_SMP |
852 | #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) | |
853 | ||
23b2899f LR |
854 | static void __init log_buf_add_cpu(void) |
855 | { | |
856 | unsigned int cpu_extra; | |
857 | ||
858 | /* | |
859 | * archs should set up cpu_possible_bits properly with | |
860 | * set_cpu_possible() after setup_arch() but just in | |
861 | * case lets ensure this is valid. | |
862 | */ | |
863 | if (num_possible_cpus() == 1) | |
864 | return; | |
865 | ||
866 | cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; | |
867 | ||
868 | /* by default this will only continue through for large > 64 CPUs */ | |
869 | if (cpu_extra <= __LOG_BUF_LEN / 2) | |
870 | return; | |
871 | ||
872 | pr_info("log_buf_len individual max cpu contribution: %d bytes\n", | |
873 | __LOG_CPU_MAX_BUF_LEN); | |
874 | pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", | |
875 | cpu_extra); | |
876 | pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); | |
877 | ||
878 | log_buf_len_update(cpu_extra + __LOG_BUF_LEN); | |
879 | } | |
2240a31d GU |
880 | #else /* !CONFIG_SMP */ |
881 | static inline void log_buf_add_cpu(void) {} | |
882 | #endif /* CONFIG_SMP */ | |
23b2899f | 883 | |
162a7e75 MT |
884 | void __init setup_log_buf(int early) |
885 | { | |
886 | unsigned long flags; | |
162a7e75 MT |
887 | char *new_log_buf; |
888 | int free; | |
889 | ||
23b2899f LR |
890 | if (log_buf != __log_buf) |
891 | return; | |
892 | ||
893 | if (!early && !new_log_buf_len) | |
894 | log_buf_add_cpu(); | |
895 | ||
162a7e75 MT |
896 | if (!new_log_buf_len) |
897 | return; | |
1da177e4 | 898 | |
162a7e75 | 899 | if (early) { |
9da791df | 900 | new_log_buf = |
70300177 | 901 | memblock_virt_alloc(new_log_buf_len, LOG_ALIGN); |
162a7e75 | 902 | } else { |
70300177 LR |
903 | new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len, |
904 | LOG_ALIGN); | |
162a7e75 MT |
905 | } |
906 | ||
907 | if (unlikely(!new_log_buf)) { | |
908 | pr_err("log_buf_len: %ld bytes not available\n", | |
909 | new_log_buf_len); | |
910 | return; | |
911 | } | |
912 | ||
07354eb1 | 913 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
162a7e75 MT |
914 | log_buf_len = new_log_buf_len; |
915 | log_buf = new_log_buf; | |
916 | new_log_buf_len = 0; | |
7ff9554b KS |
917 | free = __LOG_BUF_LEN - log_next_idx; |
918 | memcpy(log_buf, __log_buf, __LOG_BUF_LEN); | |
07354eb1 | 919 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
162a7e75 | 920 | |
f5405172 | 921 | pr_info("log_buf_len: %d bytes\n", log_buf_len); |
162a7e75 MT |
922 | pr_info("early log buf free: %d(%d%%)\n", |
923 | free, (free * 100) / __LOG_BUF_LEN); | |
924 | } | |
1da177e4 | 925 | |
2fa72c8f AC |
926 | static bool __read_mostly ignore_loglevel; |
927 | ||
928 | static int __init ignore_loglevel_setup(char *str) | |
929 | { | |
d25d9fec | 930 | ignore_loglevel = true; |
27083bac | 931 | pr_info("debug: ignoring loglevel setting.\n"); |
2fa72c8f AC |
932 | |
933 | return 0; | |
934 | } | |
935 | ||
936 | early_param("ignore_loglevel", ignore_loglevel_setup); | |
937 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); | |
938 | MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to" | |
939 | "print all kernel messages to the console."); | |
940 | ||
bfe8df3d RD |
941 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
942 | ||
674dff65 | 943 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 944 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
945 | |
946 | static int __init boot_delay_setup(char *str) | |
947 | { | |
948 | unsigned long lpj; | |
bfe8df3d RD |
949 | |
950 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
951 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
952 | ||
953 | get_option(&str, &boot_delay); | |
954 | if (boot_delay > 10 * 1000) | |
955 | boot_delay = 0; | |
956 | ||
3a3b6ed2 DY |
957 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
958 | "HZ: %d, loops_per_msec: %llu\n", | |
959 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
29e9d225 | 960 | return 0; |
bfe8df3d | 961 | } |
29e9d225 | 962 | early_param("boot_delay", boot_delay_setup); |
bfe8df3d | 963 | |
2fa72c8f | 964 | static void boot_delay_msec(int level) |
bfe8df3d RD |
965 | { |
966 | unsigned long long k; | |
967 | unsigned long timeout; | |
968 | ||
2fa72c8f AC |
969 | if ((boot_delay == 0 || system_state != SYSTEM_BOOTING) |
970 | || (level >= console_loglevel && !ignore_loglevel)) { | |
bfe8df3d | 971 | return; |
2fa72c8f | 972 | } |
bfe8df3d | 973 | |
3a3b6ed2 | 974 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
975 | |
976 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
977 | while (k) { | |
978 | k--; | |
979 | cpu_relax(); | |
980 | /* | |
981 | * use (volatile) jiffies to prevent | |
982 | * compiler reduction; loop termination via jiffies | |
983 | * is secondary and may or may not happen. | |
984 | */ | |
985 | if (time_after(jiffies, timeout)) | |
986 | break; | |
987 | touch_nmi_watchdog(); | |
988 | } | |
989 | } | |
990 | #else | |
2fa72c8f | 991 | static inline void boot_delay_msec(int level) |
bfe8df3d RD |
992 | { |
993 | } | |
994 | #endif | |
995 | ||
e99aa461 | 996 | static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); |
7ff9554b KS |
997 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
998 | ||
084681d1 KS |
999 | static size_t print_time(u64 ts, char *buf) |
1000 | { | |
1001 | unsigned long rem_nsec; | |
1002 | ||
1003 | if (!printk_time) | |
1004 | return 0; | |
1005 | ||
35dac27c RD |
1006 | rem_nsec = do_div(ts, 1000000000); |
1007 | ||
084681d1 | 1008 | if (!buf) |
35dac27c | 1009 | return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts); |
084681d1 | 1010 | |
084681d1 KS |
1011 | return sprintf(buf, "[%5lu.%06lu] ", |
1012 | (unsigned long)ts, rem_nsec / 1000); | |
1013 | } | |
1014 | ||
62e32ac3 | 1015 | static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf) |
649e6ee3 | 1016 | { |
3ce9a7c0 | 1017 | size_t len = 0; |
43a73a50 | 1018 | unsigned int prefix = (msg->facility << 3) | msg->level; |
649e6ee3 | 1019 | |
3ce9a7c0 KS |
1020 | if (syslog) { |
1021 | if (buf) { | |
43a73a50 | 1022 | len += sprintf(buf, "<%u>", prefix); |
3ce9a7c0 KS |
1023 | } else { |
1024 | len += 3; | |
43a73a50 KS |
1025 | if (prefix > 999) |
1026 | len += 3; | |
1027 | else if (prefix > 99) | |
1028 | len += 2; | |
1029 | else if (prefix > 9) | |
3ce9a7c0 KS |
1030 | len++; |
1031 | } | |
1032 | } | |
649e6ee3 | 1033 | |
084681d1 | 1034 | len += print_time(msg->ts_nsec, buf ? buf + len : NULL); |
3ce9a7c0 | 1035 | return len; |
649e6ee3 KS |
1036 | } |
1037 | ||
62e32ac3 | 1038 | static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev, |
5becfb1d | 1039 | bool syslog, char *buf, size_t size) |
7ff9554b | 1040 | { |
3ce9a7c0 KS |
1041 | const char *text = log_text(msg); |
1042 | size_t text_size = msg->text_len; | |
5becfb1d KS |
1043 | bool prefix = true; |
1044 | bool newline = true; | |
3ce9a7c0 KS |
1045 | size_t len = 0; |
1046 | ||
5becfb1d KS |
1047 | if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)) |
1048 | prefix = false; | |
1049 | ||
1050 | if (msg->flags & LOG_CONT) { | |
1051 | if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE)) | |
1052 | prefix = false; | |
1053 | ||
1054 | if (!(msg->flags & LOG_NEWLINE)) | |
1055 | newline = false; | |
1056 | } | |
1057 | ||
3ce9a7c0 KS |
1058 | do { |
1059 | const char *next = memchr(text, '\n', text_size); | |
1060 | size_t text_len; | |
1061 | ||
1062 | if (next) { | |
1063 | text_len = next - text; | |
1064 | next++; | |
1065 | text_size -= next - text; | |
1066 | } else { | |
1067 | text_len = text_size; | |
1068 | } | |
7ff9554b | 1069 | |
3ce9a7c0 KS |
1070 | if (buf) { |
1071 | if (print_prefix(msg, syslog, NULL) + | |
70498253 | 1072 | text_len + 1 >= size - len) |
3ce9a7c0 | 1073 | break; |
7ff9554b | 1074 | |
5becfb1d KS |
1075 | if (prefix) |
1076 | len += print_prefix(msg, syslog, buf + len); | |
3ce9a7c0 KS |
1077 | memcpy(buf + len, text, text_len); |
1078 | len += text_len; | |
5becfb1d KS |
1079 | if (next || newline) |
1080 | buf[len++] = '\n'; | |
3ce9a7c0 KS |
1081 | } else { |
1082 | /* SYSLOG_ACTION_* buffer size only calculation */ | |
5becfb1d KS |
1083 | if (prefix) |
1084 | len += print_prefix(msg, syslog, NULL); | |
1085 | len += text_len; | |
1086 | if (next || newline) | |
1087 | len++; | |
3ce9a7c0 | 1088 | } |
7ff9554b | 1089 | |
5becfb1d | 1090 | prefix = true; |
3ce9a7c0 KS |
1091 | text = next; |
1092 | } while (text); | |
7ff9554b | 1093 | |
7ff9554b KS |
1094 | return len; |
1095 | } | |
1096 | ||
1097 | static int syslog_print(char __user *buf, int size) | |
1098 | { | |
1099 | char *text; | |
62e32ac3 | 1100 | struct printk_log *msg; |
116e90b2 | 1101 | int len = 0; |
7ff9554b | 1102 | |
70498253 | 1103 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
7ff9554b KS |
1104 | if (!text) |
1105 | return -ENOMEM; | |
1106 | ||
116e90b2 JB |
1107 | while (size > 0) { |
1108 | size_t n; | |
eb02dac9 | 1109 | size_t skip; |
116e90b2 JB |
1110 | |
1111 | raw_spin_lock_irq(&logbuf_lock); | |
1112 | if (syslog_seq < log_first_seq) { | |
1113 | /* messages are gone, move to first one */ | |
1114 | syslog_seq = log_first_seq; | |
1115 | syslog_idx = log_first_idx; | |
5becfb1d | 1116 | syslog_prev = 0; |
eb02dac9 | 1117 | syslog_partial = 0; |
116e90b2 JB |
1118 | } |
1119 | if (syslog_seq == log_next_seq) { | |
1120 | raw_spin_unlock_irq(&logbuf_lock); | |
1121 | break; | |
1122 | } | |
eb02dac9 KS |
1123 | |
1124 | skip = syslog_partial; | |
116e90b2 | 1125 | msg = log_from_idx(syslog_idx); |
70498253 KS |
1126 | n = msg_print_text(msg, syslog_prev, true, text, |
1127 | LOG_LINE_MAX + PREFIX_MAX); | |
eb02dac9 KS |
1128 | if (n - syslog_partial <= size) { |
1129 | /* message fits into buffer, move forward */ | |
116e90b2 JB |
1130 | syslog_idx = log_next(syslog_idx); |
1131 | syslog_seq++; | |
5becfb1d | 1132 | syslog_prev = msg->flags; |
eb02dac9 KS |
1133 | n -= syslog_partial; |
1134 | syslog_partial = 0; | |
1135 | } else if (!len){ | |
1136 | /* partial read(), remember position */ | |
1137 | n = size; | |
1138 | syslog_partial += n; | |
116e90b2 JB |
1139 | } else |
1140 | n = 0; | |
1141 | raw_spin_unlock_irq(&logbuf_lock); | |
1142 | ||
1143 | if (!n) | |
1144 | break; | |
1145 | ||
eb02dac9 | 1146 | if (copy_to_user(buf, text + skip, n)) { |
116e90b2 JB |
1147 | if (!len) |
1148 | len = -EFAULT; | |
1149 | break; | |
1150 | } | |
eb02dac9 KS |
1151 | |
1152 | len += n; | |
1153 | size -= n; | |
1154 | buf += n; | |
7ff9554b | 1155 | } |
7ff9554b KS |
1156 | |
1157 | kfree(text); | |
1158 | return len; | |
1159 | } | |
1160 | ||
1161 | static int syslog_print_all(char __user *buf, int size, bool clear) | |
1162 | { | |
1163 | char *text; | |
1164 | int len = 0; | |
1165 | ||
70498253 | 1166 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
7ff9554b KS |
1167 | if (!text) |
1168 | return -ENOMEM; | |
1169 | ||
1170 | raw_spin_lock_irq(&logbuf_lock); | |
1171 | if (buf) { | |
1172 | u64 next_seq; | |
1173 | u64 seq; | |
1174 | u32 idx; | |
5becfb1d | 1175 | enum log_flags prev; |
7ff9554b KS |
1176 | |
1177 | if (clear_seq < log_first_seq) { | |
1178 | /* messages are gone, move to first available one */ | |
1179 | clear_seq = log_first_seq; | |
1180 | clear_idx = log_first_idx; | |
1181 | } | |
1182 | ||
1183 | /* | |
1184 | * Find first record that fits, including all following records, | |
1185 | * into the user-provided buffer for this dump. | |
e2ae715d | 1186 | */ |
7ff9554b KS |
1187 | seq = clear_seq; |
1188 | idx = clear_idx; | |
5becfb1d | 1189 | prev = 0; |
7ff9554b | 1190 | while (seq < log_next_seq) { |
62e32ac3 | 1191 | struct printk_log *msg = log_from_idx(idx); |
3ce9a7c0 | 1192 | |
5becfb1d | 1193 | len += msg_print_text(msg, prev, true, NULL, 0); |
e3756477 | 1194 | prev = msg->flags; |
7ff9554b KS |
1195 | idx = log_next(idx); |
1196 | seq++; | |
1197 | } | |
e2ae715d KS |
1198 | |
1199 | /* move first record forward until length fits into the buffer */ | |
7ff9554b KS |
1200 | seq = clear_seq; |
1201 | idx = clear_idx; | |
5becfb1d | 1202 | prev = 0; |
7ff9554b | 1203 | while (len > size && seq < log_next_seq) { |
62e32ac3 | 1204 | struct printk_log *msg = log_from_idx(idx); |
3ce9a7c0 | 1205 | |
5becfb1d | 1206 | len -= msg_print_text(msg, prev, true, NULL, 0); |
e3756477 | 1207 | prev = msg->flags; |
7ff9554b KS |
1208 | idx = log_next(idx); |
1209 | seq++; | |
1210 | } | |
1211 | ||
e2ae715d | 1212 | /* last message fitting into this dump */ |
7ff9554b KS |
1213 | next_seq = log_next_seq; |
1214 | ||
1215 | len = 0; | |
1216 | while (len >= 0 && seq < next_seq) { | |
62e32ac3 | 1217 | struct printk_log *msg = log_from_idx(idx); |
7ff9554b KS |
1218 | int textlen; |
1219 | ||
70498253 KS |
1220 | textlen = msg_print_text(msg, prev, true, text, |
1221 | LOG_LINE_MAX + PREFIX_MAX); | |
7ff9554b KS |
1222 | if (textlen < 0) { |
1223 | len = textlen; | |
1224 | break; | |
1225 | } | |
1226 | idx = log_next(idx); | |
1227 | seq++; | |
5becfb1d | 1228 | prev = msg->flags; |
7ff9554b KS |
1229 | |
1230 | raw_spin_unlock_irq(&logbuf_lock); | |
1231 | if (copy_to_user(buf + len, text, textlen)) | |
1232 | len = -EFAULT; | |
1233 | else | |
1234 | len += textlen; | |
1235 | raw_spin_lock_irq(&logbuf_lock); | |
1236 | ||
1237 | if (seq < log_first_seq) { | |
1238 | /* messages are gone, move to next one */ | |
1239 | seq = log_first_seq; | |
1240 | idx = log_first_idx; | |
5becfb1d | 1241 | prev = 0; |
7ff9554b KS |
1242 | } |
1243 | } | |
1244 | } | |
1245 | ||
1246 | if (clear) { | |
1247 | clear_seq = log_next_seq; | |
1248 | clear_idx = log_next_idx; | |
1249 | } | |
1250 | raw_spin_unlock_irq(&logbuf_lock); | |
1251 | ||
1252 | kfree(text); | |
1253 | return len; | |
1254 | } | |
1255 | ||
00234592 | 1256 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
1da177e4 | 1257 | { |
7ff9554b | 1258 | bool clear = false; |
a39d4a85 | 1259 | static int saved_console_loglevel = LOGLEVEL_DEFAULT; |
ee24aebf | 1260 | int error; |
1da177e4 | 1261 | |
ee24aebf LT |
1262 | error = check_syslog_permissions(type, from_file); |
1263 | if (error) | |
1264 | goto out; | |
12b3052c EP |
1265 | |
1266 | error = security_syslog(type); | |
1da177e4 LT |
1267 | if (error) |
1268 | return error; | |
1269 | ||
1270 | switch (type) { | |
d78ca3cd | 1271 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 1272 | break; |
d78ca3cd | 1273 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 1274 | break; |
d78ca3cd | 1275 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 LT |
1276 | error = -EINVAL; |
1277 | if (!buf || len < 0) | |
1278 | goto out; | |
1279 | error = 0; | |
1280 | if (!len) | |
1281 | goto out; | |
1282 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
1283 | error = -EFAULT; | |
1284 | goto out; | |
1285 | } | |
40dc5651 | 1286 | error = wait_event_interruptible(log_wait, |
7ff9554b | 1287 | syslog_seq != log_next_seq); |
cb424ffe | 1288 | if (error) |
1da177e4 | 1289 | goto out; |
7ff9554b | 1290 | error = syslog_print(buf, len); |
1da177e4 | 1291 | break; |
d78ca3cd KC |
1292 | /* Read/clear last kernel messages */ |
1293 | case SYSLOG_ACTION_READ_CLEAR: | |
7ff9554b | 1294 | clear = true; |
1da177e4 | 1295 | /* FALL THRU */ |
d78ca3cd KC |
1296 | /* Read last kernel messages */ |
1297 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 LT |
1298 | error = -EINVAL; |
1299 | if (!buf || len < 0) | |
1300 | goto out; | |
1301 | error = 0; | |
1302 | if (!len) | |
1303 | goto out; | |
1304 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
1305 | error = -EFAULT; | |
1306 | goto out; | |
1307 | } | |
7ff9554b | 1308 | error = syslog_print_all(buf, len, clear); |
1da177e4 | 1309 | break; |
d78ca3cd KC |
1310 | /* Clear ring buffer */ |
1311 | case SYSLOG_ACTION_CLEAR: | |
7ff9554b | 1312 | syslog_print_all(NULL, 0, true); |
4661e356 | 1313 | break; |
d78ca3cd KC |
1314 | /* Disable logging to console */ |
1315 | case SYSLOG_ACTION_CONSOLE_OFF: | |
a39d4a85 | 1316 | if (saved_console_loglevel == LOGLEVEL_DEFAULT) |
1aaad49e | 1317 | saved_console_loglevel = console_loglevel; |
1da177e4 LT |
1318 | console_loglevel = minimum_console_loglevel; |
1319 | break; | |
d78ca3cd KC |
1320 | /* Enable logging to console */ |
1321 | case SYSLOG_ACTION_CONSOLE_ON: | |
a39d4a85 | 1322 | if (saved_console_loglevel != LOGLEVEL_DEFAULT) { |
1aaad49e | 1323 | console_loglevel = saved_console_loglevel; |
a39d4a85 | 1324 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1aaad49e | 1325 | } |
1da177e4 | 1326 | break; |
d78ca3cd KC |
1327 | /* Set level of messages printed to console */ |
1328 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 LT |
1329 | error = -EINVAL; |
1330 | if (len < 1 || len > 8) | |
1331 | goto out; | |
1332 | if (len < minimum_console_loglevel) | |
1333 | len = minimum_console_loglevel; | |
1334 | console_loglevel = len; | |
1aaad49e | 1335 | /* Implicitly re-enable logging to console */ |
a39d4a85 | 1336 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1da177e4 LT |
1337 | error = 0; |
1338 | break; | |
d78ca3cd KC |
1339 | /* Number of chars in the log buffer */ |
1340 | case SYSLOG_ACTION_SIZE_UNREAD: | |
7ff9554b KS |
1341 | raw_spin_lock_irq(&logbuf_lock); |
1342 | if (syslog_seq < log_first_seq) { | |
1343 | /* messages are gone, move to first one */ | |
1344 | syslog_seq = log_first_seq; | |
1345 | syslog_idx = log_first_idx; | |
5becfb1d | 1346 | syslog_prev = 0; |
eb02dac9 | 1347 | syslog_partial = 0; |
7ff9554b KS |
1348 | } |
1349 | if (from_file) { | |
1350 | /* | |
1351 | * Short-cut for poll(/"proc/kmsg") which simply checks | |
1352 | * for pending data, not the size; return the count of | |
1353 | * records, not the length. | |
1354 | */ | |
e97e1267 | 1355 | error = log_next_seq - syslog_seq; |
7ff9554b | 1356 | } else { |
5becfb1d KS |
1357 | u64 seq = syslog_seq; |
1358 | u32 idx = syslog_idx; | |
1359 | enum log_flags prev = syslog_prev; | |
7ff9554b KS |
1360 | |
1361 | error = 0; | |
7ff9554b | 1362 | while (seq < log_next_seq) { |
62e32ac3 | 1363 | struct printk_log *msg = log_from_idx(idx); |
3ce9a7c0 | 1364 | |
5becfb1d | 1365 | error += msg_print_text(msg, prev, true, NULL, 0); |
7ff9554b KS |
1366 | idx = log_next(idx); |
1367 | seq++; | |
5becfb1d | 1368 | prev = msg->flags; |
7ff9554b | 1369 | } |
eb02dac9 | 1370 | error -= syslog_partial; |
7ff9554b KS |
1371 | } |
1372 | raw_spin_unlock_irq(&logbuf_lock); | |
1da177e4 | 1373 | break; |
d78ca3cd KC |
1374 | /* Size of the log buffer */ |
1375 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
1376 | error = log_buf_len; |
1377 | break; | |
1378 | default: | |
1379 | error = -EINVAL; | |
1380 | break; | |
1381 | } | |
1382 | out: | |
1383 | return error; | |
1384 | } | |
1385 | ||
1e7bfb21 | 1386 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 1387 | { |
637241a9 | 1388 | return do_syslog(type, buf, len, SYSLOG_FROM_READER); |
1da177e4 LT |
1389 | } |
1390 | ||
1da177e4 LT |
1391 | /* |
1392 | * Call the console drivers, asking them to write out | |
1393 | * log_buf[start] to log_buf[end - 1]. | |
ac751efa | 1394 | * The console_lock must be held. |
1da177e4 | 1395 | */ |
7ff9554b | 1396 | static void call_console_drivers(int level, const char *text, size_t len) |
1da177e4 | 1397 | { |
7ff9554b | 1398 | struct console *con; |
1da177e4 | 1399 | |
07c65f4d | 1400 | trace_console(text, len); |
7ff9554b KS |
1401 | |
1402 | if (level >= console_loglevel && !ignore_loglevel) | |
1403 | return; | |
1404 | if (!console_drivers) | |
1405 | return; | |
1406 | ||
1407 | for_each_console(con) { | |
1408 | if (exclusive_console && con != exclusive_console) | |
1409 | continue; | |
1410 | if (!(con->flags & CON_ENABLED)) | |
1411 | continue; | |
1412 | if (!con->write) | |
1413 | continue; | |
1414 | if (!cpu_online(smp_processor_id()) && | |
1415 | !(con->flags & CON_ANYTIME)) | |
1416 | continue; | |
1417 | con->write(con, text, len); | |
1418 | } | |
1da177e4 LT |
1419 | } |
1420 | ||
1421 | /* | |
1422 | * Zap console related locks when oopsing. Only zap at most once | |
1423 | * every 10 seconds, to leave time for slow consoles to print a | |
1424 | * full oops. | |
1425 | */ | |
1426 | static void zap_locks(void) | |
1427 | { | |
1428 | static unsigned long oops_timestamp; | |
1429 | ||
1430 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 1431 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
1432 | return; |
1433 | ||
1434 | oops_timestamp = jiffies; | |
1435 | ||
94d24fc4 | 1436 | debug_locks_off(); |
1da177e4 | 1437 | /* If a crash is occurring, make sure we can't deadlock */ |
07354eb1 | 1438 | raw_spin_lock_init(&logbuf_lock); |
1da177e4 | 1439 | /* And make sure that we print immediately */ |
5b8c4f23 | 1440 | sema_init(&console_sem, 1); |
1da177e4 LT |
1441 | } |
1442 | ||
608873ca JK |
1443 | /* |
1444 | * Check if we have any console that is capable of printing while cpu is | |
1445 | * booting or shutting down. Requires console_sem. | |
1446 | */ | |
76a8ad29 ME |
1447 | static int have_callable_console(void) |
1448 | { | |
1449 | struct console *con; | |
1450 | ||
4d091611 | 1451 | for_each_console(con) |
76a8ad29 ME |
1452 | if (con->flags & CON_ANYTIME) |
1453 | return 1; | |
1454 | ||
1455 | return 0; | |
1456 | } | |
1457 | ||
266c2e0a LT |
1458 | /* |
1459 | * Can we actually use the console at this time on this cpu? | |
1460 | * | |
5874af20 JK |
1461 | * Console drivers may assume that per-cpu resources have been allocated. So |
1462 | * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't | |
1463 | * call them until this CPU is officially up. | |
266c2e0a LT |
1464 | */ |
1465 | static inline int can_use_console(unsigned int cpu) | |
1466 | { | |
1467 | return cpu_online(cpu) || have_callable_console(); | |
1468 | } | |
1469 | ||
1470 | /* | |
1471 | * Try to get console ownership to actually show the kernel | |
1472 | * messages from a 'printk'. Return true (and with the | |
ac751efa | 1473 | * console_lock held, and 'console_locked' set) if it |
266c2e0a | 1474 | * is successful, false otherwise. |
266c2e0a | 1475 | */ |
5874af20 | 1476 | static int console_trylock_for_printk(void) |
266c2e0a | 1477 | { |
5874af20 JK |
1478 | unsigned int cpu = smp_processor_id(); |
1479 | ||
608873ca JK |
1480 | if (!console_trylock()) |
1481 | return 0; | |
1482 | /* | |
1483 | * If we can't use the console, we need to release the console | |
1484 | * semaphore by hand to avoid flushing the buffer. We need to hold the | |
1485 | * console semaphore in order to do this test safely. | |
1486 | */ | |
1487 | if (!can_use_console(cpu)) { | |
1488 | console_locked = 0; | |
bd8d7cf5 | 1489 | up_console_sem(); |
608873ca JK |
1490 | return 0; |
1491 | } | |
1492 | return 1; | |
266c2e0a | 1493 | } |
32a76006 | 1494 | |
af91322e DY |
1495 | int printk_delay_msec __read_mostly; |
1496 | ||
1497 | static inline void printk_delay(void) | |
1498 | { | |
1499 | if (unlikely(printk_delay_msec)) { | |
1500 | int m = printk_delay_msec; | |
1501 | ||
1502 | while (m--) { | |
1503 | mdelay(1); | |
1504 | touch_nmi_watchdog(); | |
1505 | } | |
1506 | } | |
1507 | } | |
1508 | ||
084681d1 KS |
1509 | /* |
1510 | * Continuation lines are buffered, and not committed to the record buffer | |
1511 | * until the line is complete, or a race forces it. The line fragments | |
1512 | * though, are printed immediately to the consoles to ensure everything has | |
1513 | * reached the console in case of a kernel crash. | |
1514 | */ | |
1515 | static struct cont { | |
1516 | char buf[LOG_LINE_MAX]; | |
1517 | size_t len; /* length == 0 means unused buffer */ | |
1518 | size_t cons; /* bytes written to console */ | |
1519 | struct task_struct *owner; /* task of first print*/ | |
1520 | u64 ts_nsec; /* time of first print */ | |
1521 | u8 level; /* log level of first message */ | |
0b90fec3 | 1522 | u8 facility; /* log facility of first message */ |
eab07260 | 1523 | enum log_flags flags; /* prefix, newline flags */ |
084681d1 KS |
1524 | bool flushed:1; /* buffer sealed and committed */ |
1525 | } cont; | |
1526 | ||
70498253 | 1527 | static void cont_flush(enum log_flags flags) |
084681d1 KS |
1528 | { |
1529 | if (cont.flushed) | |
1530 | return; | |
1531 | if (cont.len == 0) | |
1532 | return; | |
1533 | ||
eab07260 KS |
1534 | if (cont.cons) { |
1535 | /* | |
1536 | * If a fragment of this line was directly flushed to the | |
1537 | * console; wait for the console to pick up the rest of the | |
1538 | * line. LOG_NOCONS suppresses a duplicated output. | |
1539 | */ | |
1540 | log_store(cont.facility, cont.level, flags | LOG_NOCONS, | |
1541 | cont.ts_nsec, NULL, 0, cont.buf, cont.len); | |
1542 | cont.flags = flags; | |
1543 | cont.flushed = true; | |
1544 | } else { | |
1545 | /* | |
1546 | * If no fragment of this line ever reached the console, | |
1547 | * just submit it to the store and free the buffer. | |
1548 | */ | |
1549 | log_store(cont.facility, cont.level, flags, 0, | |
1550 | NULL, 0, cont.buf, cont.len); | |
1551 | cont.len = 0; | |
1552 | } | |
084681d1 KS |
1553 | } |
1554 | ||
1555 | static bool cont_add(int facility, int level, const char *text, size_t len) | |
1556 | { | |
1557 | if (cont.len && cont.flushed) | |
1558 | return false; | |
1559 | ||
1560 | if (cont.len + len > sizeof(cont.buf)) { | |
70498253 KS |
1561 | /* the line gets too long, split it up in separate records */ |
1562 | cont_flush(LOG_CONT); | |
084681d1 KS |
1563 | return false; |
1564 | } | |
1565 | ||
1566 | if (!cont.len) { | |
1567 | cont.facility = facility; | |
1568 | cont.level = level; | |
1569 | cont.owner = current; | |
1570 | cont.ts_nsec = local_clock(); | |
eab07260 | 1571 | cont.flags = 0; |
084681d1 KS |
1572 | cont.cons = 0; |
1573 | cont.flushed = false; | |
1574 | } | |
1575 | ||
1576 | memcpy(cont.buf + cont.len, text, len); | |
1577 | cont.len += len; | |
eab07260 KS |
1578 | |
1579 | if (cont.len > (sizeof(cont.buf) * 80) / 100) | |
1580 | cont_flush(LOG_CONT); | |
1581 | ||
084681d1 KS |
1582 | return true; |
1583 | } | |
1584 | ||
1585 | static size_t cont_print_text(char *text, size_t size) | |
1586 | { | |
1587 | size_t textlen = 0; | |
1588 | size_t len; | |
1589 | ||
eab07260 | 1590 | if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) { |
084681d1 KS |
1591 | textlen += print_time(cont.ts_nsec, text); |
1592 | size -= textlen; | |
1593 | } | |
1594 | ||
1595 | len = cont.len - cont.cons; | |
1596 | if (len > 0) { | |
1597 | if (len+1 > size) | |
1598 | len = size-1; | |
1599 | memcpy(text + textlen, cont.buf + cont.cons, len); | |
1600 | textlen += len; | |
1601 | cont.cons = cont.len; | |
1602 | } | |
1603 | ||
1604 | if (cont.flushed) { | |
eab07260 KS |
1605 | if (cont.flags & LOG_NEWLINE) |
1606 | text[textlen++] = '\n'; | |
084681d1 KS |
1607 | /* got everything, release buffer */ |
1608 | cont.len = 0; | |
1609 | } | |
1610 | return textlen; | |
1611 | } | |
1612 | ||
7ff9554b KS |
1613 | asmlinkage int vprintk_emit(int facility, int level, |
1614 | const char *dict, size_t dictlen, | |
1615 | const char *fmt, va_list args) | |
1da177e4 | 1616 | { |
7ff9554b | 1617 | static int recursion_bug; |
7ff9554b KS |
1618 | static char textbuf[LOG_LINE_MAX]; |
1619 | char *text = textbuf; | |
458df9fd | 1620 | size_t text_len = 0; |
5becfb1d | 1621 | enum log_flags lflags = 0; |
ac60ad74 | 1622 | unsigned long flags; |
32a76006 | 1623 | int this_cpu; |
7ff9554b | 1624 | int printed_len = 0; |
458df9fd | 1625 | bool in_sched = false; |
608873ca | 1626 | /* cpu currently holding logbuf_lock in this function */ |
f099755d | 1627 | static unsigned int logbuf_cpu = UINT_MAX; |
608873ca | 1628 | |
a39d4a85 JP |
1629 | if (level == LOGLEVEL_SCHED) { |
1630 | level = LOGLEVEL_DEFAULT; | |
458df9fd SR |
1631 | in_sched = true; |
1632 | } | |
1da177e4 | 1633 | |
2fa72c8f | 1634 | boot_delay_msec(level); |
af91322e | 1635 | printk_delay(); |
bfe8df3d | 1636 | |
1da177e4 | 1637 | /* This stops the holder of console_sem just where we want him */ |
1a9a8aef | 1638 | local_irq_save(flags); |
32a76006 IM |
1639 | this_cpu = smp_processor_id(); |
1640 | ||
1641 | /* | |
1642 | * Ouch, printk recursed into itself! | |
1643 | */ | |
7ff9554b | 1644 | if (unlikely(logbuf_cpu == this_cpu)) { |
32a76006 IM |
1645 | /* |
1646 | * If a crash is occurring during printk() on this CPU, | |
1647 | * then try to get the crash message out but make sure | |
1648 | * we can't deadlock. Otherwise just return to avoid the | |
1649 | * recursion and return - but flag the recursion so that | |
1650 | * it can be printed at the next appropriate moment: | |
1651 | */ | |
94d24fc4 | 1652 | if (!oops_in_progress && !lockdep_recursing(current)) { |
3b8945e8 | 1653 | recursion_bug = 1; |
5874af20 JK |
1654 | local_irq_restore(flags); |
1655 | return 0; | |
32a76006 IM |
1656 | } |
1657 | zap_locks(); | |
1658 | } | |
1659 | ||
a0f1ccfd | 1660 | lockdep_off(); |
07354eb1 | 1661 | raw_spin_lock(&logbuf_lock); |
7ff9554b | 1662 | logbuf_cpu = this_cpu; |
1da177e4 | 1663 | |
000a7d66 | 1664 | if (unlikely(recursion_bug)) { |
7ff9554b KS |
1665 | static const char recursion_msg[] = |
1666 | "BUG: recent printk recursion!"; | |
1667 | ||
3b8945e8 | 1668 | recursion_bug = 0; |
7ff9554b | 1669 | /* emit KERN_CRIT message */ |
034633cc | 1670 | printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0, |
000a7d66 PP |
1671 | NULL, 0, recursion_msg, |
1672 | strlen(recursion_msg)); | |
32a76006 | 1673 | } |
1da177e4 | 1674 | |
7ff9554b KS |
1675 | /* |
1676 | * The printf needs to come first; we need the syslog | |
1677 | * prefix which might be passed-in as a parameter. | |
1678 | */ | |
98e35f58 | 1679 | text_len = vscnprintf(text, sizeof(textbuf), fmt, args); |
5fd29d6c | 1680 | |
7ff9554b | 1681 | /* mark and strip a trailing newline */ |
c313af14 KS |
1682 | if (text_len && text[text_len-1] == '\n') { |
1683 | text_len--; | |
5becfb1d | 1684 | lflags |= LOG_NEWLINE; |
7ff9554b | 1685 | } |
9d90c8d9 | 1686 | |
088a52aa JP |
1687 | /* strip kernel syslog prefix and extract log level or control flags */ |
1688 | if (facility == 0) { | |
1689 | int kern_level = printk_get_level(text); | |
1690 | ||
1691 | if (kern_level) { | |
1692 | const char *end_of_header = printk_skip_level(text); | |
1693 | switch (kern_level) { | |
1694 | case '0' ... '7': | |
a39d4a85 | 1695 | if (level == LOGLEVEL_DEFAULT) |
088a52aa | 1696 | level = kern_level - '0'; |
a39d4a85 | 1697 | /* fallthrough */ |
088a52aa JP |
1698 | case 'd': /* KERN_DEFAULT */ |
1699 | lflags |= LOG_PREFIX; | |
088a52aa | 1700 | } |
e8c42d36 PM |
1701 | /* |
1702 | * No need to check length here because vscnprintf | |
1703 | * put '\0' at the end of the string. Only valid and | |
1704 | * newly printed level is detected. | |
1705 | */ | |
088a52aa JP |
1706 | text_len -= end_of_header - text; |
1707 | text = (char *)end_of_header; | |
5fd29d6c LT |
1708 | } |
1709 | } | |
1710 | ||
a39d4a85 | 1711 | if (level == LOGLEVEL_DEFAULT) |
c313af14 | 1712 | level = default_message_loglevel; |
9d90c8d9 | 1713 | |
5becfb1d KS |
1714 | if (dict) |
1715 | lflags |= LOG_PREFIX|LOG_NEWLINE; | |
ac60ad74 | 1716 | |
5becfb1d | 1717 | if (!(lflags & LOG_NEWLINE)) { |
084681d1 KS |
1718 | /* |
1719 | * Flush the conflicting buffer. An earlier newline was missing, | |
1720 | * or another task also prints continuation lines. | |
1721 | */ | |
5becfb1d | 1722 | if (cont.len && (lflags & LOG_PREFIX || cont.owner != current)) |
eab07260 | 1723 | cont_flush(LOG_NEWLINE); |
c313af14 | 1724 | |
084681d1 | 1725 | /* buffer line if possible, otherwise store it right away */ |
034633cc PM |
1726 | if (cont_add(facility, level, text, text_len)) |
1727 | printed_len += text_len; | |
1728 | else | |
1729 | printed_len += log_store(facility, level, | |
1730 | lflags | LOG_CONT, 0, | |
1731 | dict, dictlen, text, text_len); | |
5c5d5ca5 | 1732 | } else { |
084681d1 | 1733 | bool stored = false; |
c313af14 | 1734 | |
084681d1 | 1735 | /* |
d3620822 SR |
1736 | * If an earlier newline was missing and it was the same task, |
1737 | * either merge it with the current buffer and flush, or if | |
1738 | * there was a race with interrupts (prefix == true) then just | |
1739 | * flush it out and store this line separately. | |
1d3fa370 AK |
1740 | * If the preceding printk was from a different task and missed |
1741 | * a newline, flush and append the newline. | |
084681d1 | 1742 | */ |
1d3fa370 AK |
1743 | if (cont.len) { |
1744 | if (cont.owner == current && !(lflags & LOG_PREFIX)) | |
1745 | stored = cont_add(facility, level, text, | |
1746 | text_len); | |
eab07260 | 1747 | cont_flush(LOG_NEWLINE); |
c313af14 | 1748 | } |
084681d1 | 1749 | |
034633cc PM |
1750 | if (stored) |
1751 | printed_len += text_len; | |
1752 | else | |
1753 | printed_len += log_store(facility, level, lflags, 0, | |
1754 | dict, dictlen, text, text_len); | |
1da177e4 LT |
1755 | } |
1756 | ||
608873ca JK |
1757 | logbuf_cpu = UINT_MAX; |
1758 | raw_spin_unlock(&logbuf_lock); | |
5874af20 JK |
1759 | lockdep_on(); |
1760 | local_irq_restore(flags); | |
939f04be | 1761 | |
458df9fd | 1762 | /* If called from the scheduler, we can not call up(). */ |
d18bbc21 | 1763 | if (!in_sched) { |
5874af20 JK |
1764 | lockdep_off(); |
1765 | /* | |
1766 | * Disable preemption to avoid being preempted while holding | |
1767 | * console_sem which would prevent anyone from printing to | |
1768 | * console | |
1769 | */ | |
1770 | preempt_disable(); | |
1771 | ||
d18bbc21 AM |
1772 | /* |
1773 | * Try to acquire and then immediately release the console | |
1774 | * semaphore. The release will print out buffers and wake up | |
1775 | * /dev/kmsg and syslog() users. | |
1776 | */ | |
5874af20 | 1777 | if (console_trylock_for_printk()) |
d18bbc21 | 1778 | console_unlock(); |
5874af20 JK |
1779 | preempt_enable(); |
1780 | lockdep_on(); | |
d18bbc21 | 1781 | } |
76a8ad29 | 1782 | |
1da177e4 LT |
1783 | return printed_len; |
1784 | } | |
7ff9554b KS |
1785 | EXPORT_SYMBOL(vprintk_emit); |
1786 | ||
1787 | asmlinkage int vprintk(const char *fmt, va_list args) | |
1788 | { | |
a39d4a85 | 1789 | return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); |
7ff9554b | 1790 | } |
1da177e4 LT |
1791 | EXPORT_SYMBOL(vprintk); |
1792 | ||
7ff9554b KS |
1793 | asmlinkage int printk_emit(int facility, int level, |
1794 | const char *dict, size_t dictlen, | |
1795 | const char *fmt, ...) | |
1796 | { | |
1797 | va_list args; | |
1798 | int r; | |
1799 | ||
1800 | va_start(args, fmt); | |
1801 | r = vprintk_emit(facility, level, dict, dictlen, fmt, args); | |
1802 | va_end(args); | |
1803 | ||
1804 | return r; | |
1805 | } | |
1806 | EXPORT_SYMBOL(printk_emit); | |
1807 | ||
1808 | /** | |
1809 | * printk - print a kernel message | |
1810 | * @fmt: format string | |
1811 | * | |
1812 | * This is printk(). It can be called from any context. We want it to work. | |
1813 | * | |
1814 | * We try to grab the console_lock. If we succeed, it's easy - we log the | |
1815 | * output and call the console drivers. If we fail to get the semaphore, we | |
1816 | * place the output into the log buffer and return. The current holder of | |
1817 | * the console_sem will notice the new output in console_unlock(); and will | |
1818 | * send it to the consoles before releasing the lock. | |
1819 | * | |
1820 | * One effect of this deferred printing is that code which calls printk() and | |
1821 | * then changes console_loglevel may break. This is because console_loglevel | |
1822 | * is inspected when the actual printing occurs. | |
1823 | * | |
1824 | * See also: | |
1825 | * printf(3) | |
1826 | * | |
1827 | * See the vsnprintf() documentation for format string extensions over C99. | |
1828 | */ | |
722a9f92 | 1829 | asmlinkage __visible int printk(const char *fmt, ...) |
7ff9554b KS |
1830 | { |
1831 | va_list args; | |
1832 | int r; | |
1833 | ||
1834 | #ifdef CONFIG_KGDB_KDB | |
1835 | if (unlikely(kdb_trap_printk)) { | |
1836 | va_start(args, fmt); | |
1837 | r = vkdb_printf(fmt, args); | |
1838 | va_end(args); | |
1839 | return r; | |
1840 | } | |
1841 | #endif | |
1842 | va_start(args, fmt); | |
a39d4a85 | 1843 | r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); |
7ff9554b KS |
1844 | va_end(args); |
1845 | ||
1846 | return r; | |
1847 | } | |
1848 | EXPORT_SYMBOL(printk); | |
7f3a781d | 1849 | |
96efedf1 | 1850 | #else /* CONFIG_PRINTK */ |
d59745ce | 1851 | |
70498253 KS |
1852 | #define LOG_LINE_MAX 0 |
1853 | #define PREFIX_MAX 0 | |
249771b8 | 1854 | |
96efedf1 KS |
1855 | static u64 syslog_seq; |
1856 | static u32 syslog_idx; | |
eab07260 KS |
1857 | static u64 console_seq; |
1858 | static u32 console_idx; | |
96efedf1 KS |
1859 | static enum log_flags syslog_prev; |
1860 | static u64 log_first_seq; | |
1861 | static u32 log_first_idx; | |
1862 | static u64 log_next_seq; | |
eab07260 | 1863 | static enum log_flags console_prev; |
084681d1 KS |
1864 | static struct cont { |
1865 | size_t len; | |
1866 | size_t cons; | |
1867 | u8 level; | |
1868 | bool flushed:1; | |
1869 | } cont; | |
62e32ac3 | 1870 | static struct printk_log *log_from_idx(u32 idx) { return NULL; } |
7f3a781d | 1871 | static u32 log_next(u32 idx) { return 0; } |
7f3a781d | 1872 | static void call_console_drivers(int level, const char *text, size_t len) {} |
62e32ac3 | 1873 | static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev, |
5becfb1d | 1874 | bool syslog, char *buf, size_t size) { return 0; } |
084681d1 | 1875 | static size_t cont_print_text(char *text, size_t size) { return 0; } |
d59745ce | 1876 | |
7f3a781d | 1877 | #endif /* CONFIG_PRINTK */ |
d59745ce | 1878 | |
d0380e6c TG |
1879 | #ifdef CONFIG_EARLY_PRINTK |
1880 | struct console *early_console; | |
1881 | ||
722a9f92 | 1882 | asmlinkage __visible void early_printk(const char *fmt, ...) |
d0380e6c TG |
1883 | { |
1884 | va_list ap; | |
1dc6244b JP |
1885 | char buf[512]; |
1886 | int n; | |
1887 | ||
1888 | if (!early_console) | |
1889 | return; | |
d0380e6c TG |
1890 | |
1891 | va_start(ap, fmt); | |
1dc6244b | 1892 | n = vscnprintf(buf, sizeof(buf), fmt, ap); |
d0380e6c | 1893 | va_end(ap); |
1dc6244b JP |
1894 | |
1895 | early_console->write(early_console, buf, n); | |
d0380e6c TG |
1896 | } |
1897 | #endif | |
1898 | ||
f7511d5f ST |
1899 | static int __add_preferred_console(char *name, int idx, char *options, |
1900 | char *brl_options) | |
1901 | { | |
1902 | struct console_cmdline *c; | |
1903 | int i; | |
1904 | ||
1905 | /* | |
1906 | * See if this tty is not yet registered, and | |
1907 | * if we have a slot free. | |
1908 | */ | |
23475408 JP |
1909 | for (i = 0, c = console_cmdline; |
1910 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
1911 | i++, c++) { | |
1912 | if (strcmp(c->name, name) == 0 && c->index == idx) { | |
1913 | if (!brl_options) | |
1914 | selected_console = i; | |
1915 | return 0; | |
f7511d5f | 1916 | } |
23475408 | 1917 | } |
f7511d5f ST |
1918 | if (i == MAX_CMDLINECONSOLES) |
1919 | return -E2BIG; | |
1920 | if (!brl_options) | |
1921 | selected_console = i; | |
f7511d5f ST |
1922 | strlcpy(c->name, name, sizeof(c->name)); |
1923 | c->options = options; | |
bbeddf52 JP |
1924 | braille_set_options(c, brl_options); |
1925 | ||
f7511d5f ST |
1926 | c->index = idx; |
1927 | return 0; | |
1928 | } | |
2ea1c539 | 1929 | /* |
0b90fec3 AE |
1930 | * Set up a console. Called via do_early_param() in init/main.c |
1931 | * for each "console=" parameter in the boot command line. | |
2ea1c539 JB |
1932 | */ |
1933 | static int __init console_setup(char *str) | |
1934 | { | |
0b90fec3 | 1935 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ |
f7511d5f | 1936 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
1937 | int idx; |
1938 | ||
bbeddf52 JP |
1939 | if (_braille_console_setup(&str, &brl_options)) |
1940 | return 1; | |
f7511d5f | 1941 | |
2ea1c539 JB |
1942 | /* |
1943 | * Decode str into name, index, options. | |
1944 | */ | |
1945 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
1946 | strcpy(buf, "ttyS"); |
1947 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 1948 | } else { |
eaa944af | 1949 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 1950 | } |
eaa944af | 1951 | buf[sizeof(buf) - 1] = 0; |
249771b8 AE |
1952 | options = strchr(str, ','); |
1953 | if (options) | |
2ea1c539 JB |
1954 | *(options++) = 0; |
1955 | #ifdef __sparc__ | |
1956 | if (!strcmp(str, "ttya")) | |
eaa944af | 1957 | strcpy(buf, "ttyS0"); |
2ea1c539 | 1958 | if (!strcmp(str, "ttyb")) |
eaa944af | 1959 | strcpy(buf, "ttyS1"); |
2ea1c539 | 1960 | #endif |
eaa944af | 1961 | for (s = buf; *s; s++) |
249771b8 | 1962 | if (isdigit(*s) || *s == ',') |
2ea1c539 JB |
1963 | break; |
1964 | idx = simple_strtoul(s, NULL, 10); | |
1965 | *s = 0; | |
1966 | ||
f7511d5f | 1967 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 1968 | console_set_on_cmdline = 1; |
2ea1c539 JB |
1969 | return 1; |
1970 | } | |
1971 | __setup("console=", console_setup); | |
1972 | ||
3c0547ba MM |
1973 | /** |
1974 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
1975 | * @name: device name |
1976 | * @idx: device index | |
1977 | * @options: options for this console | |
3c0547ba MM |
1978 | * |
1979 | * The last preferred console added will be used for kernel messages | |
1980 | * and stdin/out/err for init. Normally this is used by console_setup | |
1981 | * above to handle user-supplied console arguments; however it can also | |
1982 | * be used by arch-specific code either to override the user or more | |
1983 | * commonly to provide a default console (ie from PROM variables) when | |
1984 | * the user has not supplied one. | |
1985 | */ | |
fb445ee5 | 1986 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 1987 | { |
f7511d5f | 1988 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
1989 | } |
1990 | ||
b6b1d877 | 1991 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
1992 | { |
1993 | struct console_cmdline *c; | |
1994 | int i; | |
1995 | ||
23475408 JP |
1996 | for (i = 0, c = console_cmdline; |
1997 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
1998 | i++, c++) | |
1999 | if (strcmp(c->name, name) == 0 && c->index == idx) { | |
2000 | strlcpy(c->name, name_new, sizeof(c->name)); | |
23475408 JP |
2001 | c->options = options; |
2002 | c->index = idx_new; | |
2003 | return i; | |
18a8bd94 YL |
2004 | } |
2005 | /* not found */ | |
2006 | return -1; | |
2007 | } | |
2008 | ||
d25d9fec | 2009 | bool console_suspend_enabled = true; |
8f4ce8c3 AS |
2010 | EXPORT_SYMBOL(console_suspend_enabled); |
2011 | ||
2012 | static int __init console_suspend_disable(char *str) | |
2013 | { | |
d25d9fec | 2014 | console_suspend_enabled = false; |
8f4ce8c3 AS |
2015 | return 1; |
2016 | } | |
2017 | __setup("no_console_suspend", console_suspend_disable); | |
134620f7 YZ |
2018 | module_param_named(console_suspend, console_suspend_enabled, |
2019 | bool, S_IRUGO | S_IWUSR); | |
2020 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" | |
2021 | " and hibernate operations"); | |
8f4ce8c3 | 2022 | |
557240b4 LT |
2023 | /** |
2024 | * suspend_console - suspend the console subsystem | |
2025 | * | |
2026 | * This disables printk() while we go into suspend states | |
2027 | */ | |
2028 | void suspend_console(void) | |
2029 | { | |
8f4ce8c3 AS |
2030 | if (!console_suspend_enabled) |
2031 | return; | |
0d63081d | 2032 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
ac751efa | 2033 | console_lock(); |
557240b4 | 2034 | console_suspended = 1; |
bd8d7cf5 | 2035 | up_console_sem(); |
557240b4 LT |
2036 | } |
2037 | ||
2038 | void resume_console(void) | |
2039 | { | |
8f4ce8c3 AS |
2040 | if (!console_suspend_enabled) |
2041 | return; | |
bd8d7cf5 | 2042 | down_console_sem(); |
557240b4 | 2043 | console_suspended = 0; |
ac751efa | 2044 | console_unlock(); |
557240b4 LT |
2045 | } |
2046 | ||
034260d6 KC |
2047 | /** |
2048 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
2049 | * @self: notifier struct | |
2050 | * @action: CPU hotplug event | |
2051 | * @hcpu: unused | |
2052 | * | |
2053 | * If printk() is called from a CPU that is not online yet, the messages | |
2054 | * will be spooled but will not show up on the console. This function is | |
2055 | * called when a new CPU comes online (or fails to come up), and ensures | |
2056 | * that any such output gets printed. | |
2057 | */ | |
0db0628d | 2058 | static int console_cpu_notify(struct notifier_block *self, |
034260d6 KC |
2059 | unsigned long action, void *hcpu) |
2060 | { | |
2061 | switch (action) { | |
2062 | case CPU_ONLINE: | |
2063 | case CPU_DEAD: | |
034260d6 KC |
2064 | case CPU_DOWN_FAILED: |
2065 | case CPU_UP_CANCELED: | |
ac751efa TH |
2066 | console_lock(); |
2067 | console_unlock(); | |
034260d6 KC |
2068 | } |
2069 | return NOTIFY_OK; | |
2070 | } | |
2071 | ||
1da177e4 | 2072 | /** |
ac751efa | 2073 | * console_lock - lock the console system for exclusive use. |
1da177e4 | 2074 | * |
ac751efa | 2075 | * Acquires a lock which guarantees that the caller has |
1da177e4 LT |
2076 | * exclusive access to the console system and the console_drivers list. |
2077 | * | |
2078 | * Can sleep, returns nothing. | |
2079 | */ | |
ac751efa | 2080 | void console_lock(void) |
1da177e4 | 2081 | { |
6b898c07 DV |
2082 | might_sleep(); |
2083 | ||
bd8d7cf5 | 2084 | down_console_sem(); |
403f3075 AH |
2085 | if (console_suspended) |
2086 | return; | |
1da177e4 LT |
2087 | console_locked = 1; |
2088 | console_may_schedule = 1; | |
2089 | } | |
ac751efa | 2090 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 2091 | |
ac751efa TH |
2092 | /** |
2093 | * console_trylock - try to lock the console system for exclusive use. | |
2094 | * | |
0b90fec3 AE |
2095 | * Try to acquire a lock which guarantees that the caller has exclusive |
2096 | * access to the console system and the console_drivers list. | |
ac751efa TH |
2097 | * |
2098 | * returns 1 on success, and 0 on failure to acquire the lock. | |
2099 | */ | |
2100 | int console_trylock(void) | |
1da177e4 | 2101 | { |
bd8d7cf5 | 2102 | if (down_trylock_console_sem()) |
ac751efa | 2103 | return 0; |
403f3075 | 2104 | if (console_suspended) { |
bd8d7cf5 | 2105 | up_console_sem(); |
ac751efa | 2106 | return 0; |
403f3075 | 2107 | } |
1da177e4 LT |
2108 | console_locked = 1; |
2109 | console_may_schedule = 0; | |
ac751efa | 2110 | return 1; |
1da177e4 | 2111 | } |
ac751efa | 2112 | EXPORT_SYMBOL(console_trylock); |
1da177e4 LT |
2113 | |
2114 | int is_console_locked(void) | |
2115 | { | |
2116 | return console_locked; | |
2117 | } | |
1da177e4 | 2118 | |
eab07260 KS |
2119 | static void console_cont_flush(char *text, size_t size) |
2120 | { | |
2121 | unsigned long flags; | |
2122 | size_t len; | |
2123 | ||
2124 | raw_spin_lock_irqsave(&logbuf_lock, flags); | |
2125 | ||
2126 | if (!cont.len) | |
2127 | goto out; | |
2128 | ||
2129 | /* | |
2130 | * We still queue earlier records, likely because the console was | |
2131 | * busy. The earlier ones need to be printed before this one, we | |
2132 | * did not flush any fragment so far, so just let it queue up. | |
2133 | */ | |
2134 | if (console_seq < log_next_seq && !cont.cons) | |
2135 | goto out; | |
2136 | ||
2137 | len = cont_print_text(text, size); | |
2138 | raw_spin_unlock(&logbuf_lock); | |
2139 | stop_critical_timings(); | |
2140 | call_console_drivers(cont.level, text, len); | |
2141 | start_critical_timings(); | |
2142 | local_irq_restore(flags); | |
2143 | return; | |
2144 | out: | |
2145 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); | |
2146 | } | |
7ff9554b | 2147 | |
1da177e4 | 2148 | /** |
ac751efa | 2149 | * console_unlock - unlock the console system |
1da177e4 | 2150 | * |
ac751efa | 2151 | * Releases the console_lock which the caller holds on the console system |
1da177e4 LT |
2152 | * and the console driver list. |
2153 | * | |
ac751efa TH |
2154 | * While the console_lock was held, console output may have been buffered |
2155 | * by printk(). If this is the case, console_unlock(); emits | |
2156 | * the output prior to releasing the lock. | |
1da177e4 | 2157 | * |
7f3a781d | 2158 | * If there is output waiting, we wake /dev/kmsg and syslog() users. |
1da177e4 | 2159 | * |
ac751efa | 2160 | * console_unlock(); may be called from any context. |
1da177e4 | 2161 | */ |
ac751efa | 2162 | void console_unlock(void) |
1da177e4 | 2163 | { |
70498253 | 2164 | static char text[LOG_LINE_MAX + PREFIX_MAX]; |
7ff9554b | 2165 | static u64 seen_seq; |
1da177e4 | 2166 | unsigned long flags; |
7ff9554b KS |
2167 | bool wake_klogd = false; |
2168 | bool retry; | |
1da177e4 | 2169 | |
557240b4 | 2170 | if (console_suspended) { |
bd8d7cf5 | 2171 | up_console_sem(); |
557240b4 LT |
2172 | return; |
2173 | } | |
78944e54 AD |
2174 | |
2175 | console_may_schedule = 0; | |
2176 | ||
084681d1 | 2177 | /* flush buffered message fragment immediately to console */ |
eab07260 | 2178 | console_cont_flush(text, sizeof(text)); |
4f2a8d3c | 2179 | again: |
7ff9554b | 2180 | for (;;) { |
62e32ac3 | 2181 | struct printk_log *msg; |
3ce9a7c0 | 2182 | size_t len; |
7ff9554b KS |
2183 | int level; |
2184 | ||
07354eb1 | 2185 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
7ff9554b KS |
2186 | if (seen_seq != log_next_seq) { |
2187 | wake_klogd = true; | |
2188 | seen_seq = log_next_seq; | |
2189 | } | |
2190 | ||
2191 | if (console_seq < log_first_seq) { | |
84b5ec8a WD |
2192 | len = sprintf(text, "** %u printk messages dropped ** ", |
2193 | (unsigned)(log_first_seq - console_seq)); | |
2194 | ||
7ff9554b KS |
2195 | /* messages are gone, move to first one */ |
2196 | console_seq = log_first_seq; | |
2197 | console_idx = log_first_idx; | |
5becfb1d | 2198 | console_prev = 0; |
84b5ec8a WD |
2199 | } else { |
2200 | len = 0; | |
7ff9554b | 2201 | } |
084681d1 | 2202 | skip: |
7ff9554b KS |
2203 | if (console_seq == log_next_seq) |
2204 | break; | |
2205 | ||
2206 | msg = log_from_idx(console_idx); | |
084681d1 KS |
2207 | if (msg->flags & LOG_NOCONS) { |
2208 | /* | |
2209 | * Skip record we have buffered and already printed | |
2210 | * directly to the console when we received it. | |
2211 | */ | |
2212 | console_idx = log_next(console_idx); | |
2213 | console_seq++; | |
68b6507d KS |
2214 | /* |
2215 | * We will get here again when we register a new | |
2216 | * CON_PRINTBUFFER console. Clear the flag so we | |
2217 | * will properly dump everything later. | |
2218 | */ | |
2219 | msg->flags &= ~LOG_NOCONS; | |
eab07260 | 2220 | console_prev = msg->flags; |
084681d1 KS |
2221 | goto skip; |
2222 | } | |
649e6ee3 | 2223 | |
084681d1 | 2224 | level = msg->level; |
84b5ec8a WD |
2225 | len += msg_print_text(msg, console_prev, false, |
2226 | text + len, sizeof(text) - len); | |
7ff9554b KS |
2227 | console_idx = log_next(console_idx); |
2228 | console_seq++; | |
5becfb1d | 2229 | console_prev = msg->flags; |
07354eb1 | 2230 | raw_spin_unlock(&logbuf_lock); |
7ff9554b | 2231 | |
81d68a96 | 2232 | stop_critical_timings(); /* don't trace print latency */ |
7ff9554b | 2233 | call_console_drivers(level, text, len); |
81d68a96 | 2234 | start_critical_timings(); |
1da177e4 LT |
2235 | local_irq_restore(flags); |
2236 | } | |
2237 | console_locked = 0; | |
fe3d8ad3 FT |
2238 | |
2239 | /* Release the exclusive_console once it is used */ | |
2240 | if (unlikely(exclusive_console)) | |
2241 | exclusive_console = NULL; | |
2242 | ||
07354eb1 | 2243 | raw_spin_unlock(&logbuf_lock); |
4f2a8d3c | 2244 | |
bd8d7cf5 | 2245 | up_console_sem(); |
4f2a8d3c PZ |
2246 | |
2247 | /* | |
2248 | * Someone could have filled up the buffer again, so re-check if there's | |
2249 | * something to flush. In case we cannot trylock the console_sem again, | |
2250 | * there's a new owner and the console_unlock() from them will do the | |
2251 | * flush, no worries. | |
2252 | */ | |
07354eb1 | 2253 | raw_spin_lock(&logbuf_lock); |
7ff9554b | 2254 | retry = console_seq != log_next_seq; |
09dc3cf9 PZ |
2255 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
2256 | ||
4f2a8d3c PZ |
2257 | if (retry && console_trylock()) |
2258 | goto again; | |
2259 | ||
e3e8a75d KK |
2260 | if (wake_klogd) |
2261 | wake_up_klogd(); | |
1da177e4 | 2262 | } |
ac751efa | 2263 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 2264 | |
ddad86c2 MW |
2265 | /** |
2266 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
2267 | * |
2268 | * If the console code is currently allowed to sleep, and | |
2269 | * if this CPU should yield the CPU to another task, do | |
2270 | * so here. | |
2271 | * | |
ac751efa | 2272 | * Must be called within console_lock();. |
1da177e4 LT |
2273 | */ |
2274 | void __sched console_conditional_schedule(void) | |
2275 | { | |
2276 | if (console_may_schedule) | |
2277 | cond_resched(); | |
2278 | } | |
2279 | EXPORT_SYMBOL(console_conditional_schedule); | |
2280 | ||
1da177e4 LT |
2281 | void console_unblank(void) |
2282 | { | |
2283 | struct console *c; | |
2284 | ||
2285 | /* | |
2286 | * console_unblank can no longer be called in interrupt context unless | |
2287 | * oops_in_progress is set to 1.. | |
2288 | */ | |
2289 | if (oops_in_progress) { | |
bd8d7cf5 | 2290 | if (down_trylock_console_sem() != 0) |
1da177e4 LT |
2291 | return; |
2292 | } else | |
ac751efa | 2293 | console_lock(); |
1da177e4 LT |
2294 | |
2295 | console_locked = 1; | |
2296 | console_may_schedule = 0; | |
4d091611 | 2297 | for_each_console(c) |
1da177e4 LT |
2298 | if ((c->flags & CON_ENABLED) && c->unblank) |
2299 | c->unblank(); | |
ac751efa | 2300 | console_unlock(); |
1da177e4 | 2301 | } |
1da177e4 LT |
2302 | |
2303 | /* | |
2304 | * Return the console tty driver structure and its associated index | |
2305 | */ | |
2306 | struct tty_driver *console_device(int *index) | |
2307 | { | |
2308 | struct console *c; | |
2309 | struct tty_driver *driver = NULL; | |
2310 | ||
ac751efa | 2311 | console_lock(); |
4d091611 | 2312 | for_each_console(c) { |
1da177e4 LT |
2313 | if (!c->device) |
2314 | continue; | |
2315 | driver = c->device(c, index); | |
2316 | if (driver) | |
2317 | break; | |
2318 | } | |
ac751efa | 2319 | console_unlock(); |
1da177e4 LT |
2320 | return driver; |
2321 | } | |
2322 | ||
2323 | /* | |
2324 | * Prevent further output on the passed console device so that (for example) | |
2325 | * serial drivers can disable console output before suspending a port, and can | |
2326 | * re-enable output afterwards. | |
2327 | */ | |
2328 | void console_stop(struct console *console) | |
2329 | { | |
ac751efa | 2330 | console_lock(); |
1da177e4 | 2331 | console->flags &= ~CON_ENABLED; |
ac751efa | 2332 | console_unlock(); |
1da177e4 LT |
2333 | } |
2334 | EXPORT_SYMBOL(console_stop); | |
2335 | ||
2336 | void console_start(struct console *console) | |
2337 | { | |
ac751efa | 2338 | console_lock(); |
1da177e4 | 2339 | console->flags |= CON_ENABLED; |
ac751efa | 2340 | console_unlock(); |
1da177e4 LT |
2341 | } |
2342 | EXPORT_SYMBOL(console_start); | |
2343 | ||
7bf69395 FDN |
2344 | static int __read_mostly keep_bootcon; |
2345 | ||
2346 | static int __init keep_bootcon_setup(char *str) | |
2347 | { | |
2348 | keep_bootcon = 1; | |
27083bac | 2349 | pr_info("debug: skip boot console de-registration.\n"); |
7bf69395 FDN |
2350 | |
2351 | return 0; | |
2352 | } | |
2353 | ||
2354 | early_param("keep_bootcon", keep_bootcon_setup); | |
2355 | ||
1da177e4 LT |
2356 | /* |
2357 | * The console driver calls this routine during kernel initialization | |
2358 | * to register the console printing procedure with printk() and to | |
2359 | * print any messages that were printed by the kernel before the | |
2360 | * console driver was initialized. | |
4d091611 RG |
2361 | * |
2362 | * This can happen pretty early during the boot process (because of | |
2363 | * early_printk) - sometimes before setup_arch() completes - be careful | |
2364 | * of what kernel features are used - they may not be initialised yet. | |
2365 | * | |
2366 | * There are two types of consoles - bootconsoles (early_printk) and | |
2367 | * "real" consoles (everything which is not a bootconsole) which are | |
2368 | * handled differently. | |
2369 | * - Any number of bootconsoles can be registered at any time. | |
2370 | * - As soon as a "real" console is registered, all bootconsoles | |
2371 | * will be unregistered automatically. | |
2372 | * - Once a "real" console is registered, any attempt to register a | |
2373 | * bootconsoles will be rejected | |
1da177e4 | 2374 | */ |
4d091611 | 2375 | void register_console(struct console *newcon) |
1da177e4 | 2376 | { |
40dc5651 | 2377 | int i; |
1da177e4 | 2378 | unsigned long flags; |
4d091611 | 2379 | struct console *bcon = NULL; |
23475408 | 2380 | struct console_cmdline *c; |
1da177e4 | 2381 | |
16cf48a6 AB |
2382 | if (console_drivers) |
2383 | for_each_console(bcon) | |
2384 | if (WARN(bcon == newcon, | |
2385 | "console '%s%d' already registered\n", | |
2386 | bcon->name, bcon->index)) | |
2387 | return; | |
2388 | ||
4d091611 RG |
2389 | /* |
2390 | * before we register a new CON_BOOT console, make sure we don't | |
2391 | * already have a valid console | |
2392 | */ | |
2393 | if (console_drivers && newcon->flags & CON_BOOT) { | |
2394 | /* find the last or real console */ | |
2395 | for_each_console(bcon) { | |
2396 | if (!(bcon->flags & CON_BOOT)) { | |
27083bac | 2397 | pr_info("Too late to register bootconsole %s%d\n", |
4d091611 RG |
2398 | newcon->name, newcon->index); |
2399 | return; | |
2400 | } | |
2401 | } | |
69331af7 GH |
2402 | } |
2403 | ||
4d091611 RG |
2404 | if (console_drivers && console_drivers->flags & CON_BOOT) |
2405 | bcon = console_drivers; | |
2406 | ||
2407 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
2408 | preferred_console = selected_console; |
2409 | ||
4d091611 RG |
2410 | if (newcon->early_setup) |
2411 | newcon->early_setup(); | |
18a8bd94 | 2412 | |
1da177e4 LT |
2413 | /* |
2414 | * See if we want to use this console driver. If we | |
2415 | * didn't select a console we take the first one | |
2416 | * that registers here. | |
2417 | */ | |
2418 | if (preferred_console < 0) { | |
4d091611 RG |
2419 | if (newcon->index < 0) |
2420 | newcon->index = 0; | |
2421 | if (newcon->setup == NULL || | |
2422 | newcon->setup(newcon, NULL) == 0) { | |
2423 | newcon->flags |= CON_ENABLED; | |
2424 | if (newcon->device) { | |
2425 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
2426 | preferred_console = 0; |
2427 | } | |
1da177e4 LT |
2428 | } |
2429 | } | |
2430 | ||
2431 | /* | |
2432 | * See if this console matches one we selected on | |
2433 | * the command line. | |
2434 | */ | |
23475408 JP |
2435 | for (i = 0, c = console_cmdline; |
2436 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2437 | i++, c++) { | |
2438 | if (strcmp(c->name, newcon->name) != 0) | |
1da177e4 | 2439 | continue; |
4d091611 | 2440 | if (newcon->index >= 0 && |
23475408 | 2441 | newcon->index != c->index) |
1da177e4 | 2442 | continue; |
4d091611 | 2443 | if (newcon->index < 0) |
23475408 | 2444 | newcon->index = c->index; |
bbeddf52 | 2445 | |
23475408 | 2446 | if (_braille_register_console(newcon, c)) |
f7511d5f | 2447 | return; |
bbeddf52 | 2448 | |
4d091611 RG |
2449 | if (newcon->setup && |
2450 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 2451 | break; |
4d091611 | 2452 | newcon->flags |= CON_ENABLED; |
23475408 | 2453 | newcon->index = c->index; |
ab4af03a | 2454 | if (i == selected_console) { |
4d091611 | 2455 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
2456 | preferred_console = selected_console; |
2457 | } | |
1da177e4 LT |
2458 | break; |
2459 | } | |
2460 | ||
4d091611 | 2461 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
2462 | return; |
2463 | ||
8259cf43 RG |
2464 | /* |
2465 | * If we have a bootconsole, and are switching to a real console, | |
2466 | * don't print everything out again, since when the boot console, and | |
2467 | * the real console are the same physical device, it's annoying to | |
2468 | * see the beginning boot messages twice | |
2469 | */ | |
2470 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 2471 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
2472 | |
2473 | /* | |
2474 | * Put this console in the list - keep the | |
2475 | * preferred driver at the head of the list. | |
2476 | */ | |
ac751efa | 2477 | console_lock(); |
4d091611 RG |
2478 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
2479 | newcon->next = console_drivers; | |
2480 | console_drivers = newcon; | |
2481 | if (newcon->next) | |
2482 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 2483 | } else { |
4d091611 RG |
2484 | newcon->next = console_drivers->next; |
2485 | console_drivers->next = newcon; | |
1da177e4 | 2486 | } |
4d091611 | 2487 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 | 2488 | /* |
ac751efa | 2489 | * console_unlock(); will print out the buffered messages |
1da177e4 LT |
2490 | * for us. |
2491 | */ | |
07354eb1 | 2492 | raw_spin_lock_irqsave(&logbuf_lock, flags); |
7ff9554b KS |
2493 | console_seq = syslog_seq; |
2494 | console_idx = syslog_idx; | |
5becfb1d | 2495 | console_prev = syslog_prev; |
07354eb1 | 2496 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
fe3d8ad3 FT |
2497 | /* |
2498 | * We're about to replay the log buffer. Only do this to the | |
2499 | * just-registered console to avoid excessive message spam to | |
2500 | * the already-registered consoles. | |
2501 | */ | |
2502 | exclusive_console = newcon; | |
1da177e4 | 2503 | } |
ac751efa | 2504 | console_unlock(); |
fbc92a34 | 2505 | console_sysfs_notify(); |
8259cf43 RG |
2506 | |
2507 | /* | |
2508 | * By unregistering the bootconsoles after we enable the real console | |
2509 | * we get the "console xxx enabled" message on all the consoles - | |
2510 | * boot consoles, real consoles, etc - this is to ensure that end | |
2511 | * users know there might be something in the kernel's log buffer that | |
2512 | * went to the bootconsole (that they do not see on the real console) | |
2513 | */ | |
27083bac | 2514 | pr_info("%sconsole [%s%d] enabled\n", |
6b802394 KC |
2515 | (newcon->flags & CON_BOOT) ? "boot" : "" , |
2516 | newcon->name, newcon->index); | |
7bf69395 FDN |
2517 | if (bcon && |
2518 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && | |
2519 | !keep_bootcon) { | |
6b802394 KC |
2520 | /* We need to iterate through all boot consoles, to make |
2521 | * sure we print everything out, before we unregister them. | |
8259cf43 | 2522 | */ |
8259cf43 RG |
2523 | for_each_console(bcon) |
2524 | if (bcon->flags & CON_BOOT) | |
2525 | unregister_console(bcon); | |
8259cf43 | 2526 | } |
1da177e4 LT |
2527 | } |
2528 | EXPORT_SYMBOL(register_console); | |
2529 | ||
40dc5651 | 2530 | int unregister_console(struct console *console) |
1da177e4 | 2531 | { |
40dc5651 | 2532 | struct console *a, *b; |
bbeddf52 | 2533 | int res; |
1da177e4 | 2534 | |
27083bac | 2535 | pr_info("%sconsole [%s%d] disabled\n", |
6b802394 KC |
2536 | (console->flags & CON_BOOT) ? "boot" : "" , |
2537 | console->name, console->index); | |
2538 | ||
bbeddf52 JP |
2539 | res = _braille_unregister_console(console); |
2540 | if (res) | |
2541 | return res; | |
f7511d5f | 2542 | |
bbeddf52 | 2543 | res = 1; |
ac751efa | 2544 | console_lock(); |
1da177e4 LT |
2545 | if (console_drivers == console) { |
2546 | console_drivers=console->next; | |
2547 | res = 0; | |
e9b15b54 | 2548 | } else if (console_drivers) { |
1da177e4 LT |
2549 | for (a=console_drivers->next, b=console_drivers ; |
2550 | a; b=a, a=b->next) { | |
2551 | if (a == console) { | |
2552 | b->next = a->next; | |
2553 | res = 0; | |
2554 | break; | |
40dc5651 | 2555 | } |
1da177e4 LT |
2556 | } |
2557 | } | |
40dc5651 | 2558 | |
69331af7 | 2559 | /* |
ab4af03a GE |
2560 | * If this isn't the last console and it has CON_CONSDEV set, we |
2561 | * need to set it on the next preferred console. | |
1da177e4 | 2562 | */ |
69331af7 | 2563 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 2564 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 | 2565 | |
7fa21dd8 | 2566 | console->flags &= ~CON_ENABLED; |
ac751efa | 2567 | console_unlock(); |
fbc92a34 | 2568 | console_sysfs_notify(); |
1da177e4 LT |
2569 | return res; |
2570 | } | |
2571 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 2572 | |
034260d6 | 2573 | static int __init printk_late_init(void) |
0c5564bd | 2574 | { |
4d091611 RG |
2575 | struct console *con; |
2576 | ||
2577 | for_each_console(con) { | |
4c30c6f5 | 2578 | if (!keep_bootcon && con->flags & CON_BOOT) { |
42c2c8c8 | 2579 | unregister_console(con); |
cb00e99c | 2580 | } |
0c5564bd | 2581 | } |
034260d6 | 2582 | hotcpu_notifier(console_cpu_notify, 0); |
0c5564bd RG |
2583 | return 0; |
2584 | } | |
034260d6 | 2585 | late_initcall(printk_late_init); |
0c5564bd | 2586 | |
7ef3d2fd | 2587 | #if defined CONFIG_PRINTK |
dc72c32e FW |
2588 | /* |
2589 | * Delayed printk version, for scheduler-internal messages: | |
2590 | */ | |
dc72c32e | 2591 | #define PRINTK_PENDING_WAKEUP 0x01 |
458df9fd | 2592 | #define PRINTK_PENDING_OUTPUT 0x02 |
dc72c32e FW |
2593 | |
2594 | static DEFINE_PER_CPU(int, printk_pending); | |
dc72c32e FW |
2595 | |
2596 | static void wake_up_klogd_work_func(struct irq_work *irq_work) | |
2597 | { | |
2598 | int pending = __this_cpu_xchg(printk_pending, 0); | |
2599 | ||
458df9fd SR |
2600 | if (pending & PRINTK_PENDING_OUTPUT) { |
2601 | /* If trylock fails, someone else is doing the printing */ | |
2602 | if (console_trylock()) | |
2603 | console_unlock(); | |
dc72c32e FW |
2604 | } |
2605 | ||
2606 | if (pending & PRINTK_PENDING_WAKEUP) | |
2607 | wake_up_interruptible(&log_wait); | |
2608 | } | |
2609 | ||
2610 | static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { | |
2611 | .func = wake_up_klogd_work_func, | |
2612 | .flags = IRQ_WORK_LAZY, | |
2613 | }; | |
2614 | ||
2615 | void wake_up_klogd(void) | |
2616 | { | |
2617 | preempt_disable(); | |
2618 | if (waitqueue_active(&log_wait)) { | |
2619 | this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); | |
bb964a92 | 2620 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
dc72c32e FW |
2621 | } |
2622 | preempt_enable(); | |
2623 | } | |
717115e1 | 2624 | |
aac74dc4 | 2625 | int printk_deferred(const char *fmt, ...) |
600e1458 | 2626 | { |
600e1458 | 2627 | va_list args; |
600e1458 PZ |
2628 | int r; |
2629 | ||
81954606 | 2630 | preempt_disable(); |
600e1458 | 2631 | va_start(args, fmt); |
a39d4a85 | 2632 | r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args); |
600e1458 PZ |
2633 | va_end(args); |
2634 | ||
458df9fd | 2635 | __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); |
bb964a92 | 2636 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
81954606 | 2637 | preempt_enable(); |
600e1458 PZ |
2638 | |
2639 | return r; | |
2640 | } | |
2641 | ||
1da177e4 LT |
2642 | /* |
2643 | * printk rate limiting, lifted from the networking subsystem. | |
2644 | * | |
641de9d8 UKK |
2645 | * This enforces a rate limit: not more than 10 kernel messages |
2646 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 2647 | */ |
641de9d8 UKK |
2648 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
2649 | ||
5c828713 | 2650 | int __printk_ratelimit(const char *func) |
1da177e4 | 2651 | { |
5c828713 | 2652 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 2653 | } |
5c828713 | 2654 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
2655 | |
2656 | /** | |
2657 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
2658 | * @caller_jiffies: pointer to caller's state | |
2659 | * @interval_msecs: minimum interval between prints | |
2660 | * | |
2661 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
2662 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
2663 | * returned true. | |
2664 | */ | |
2665 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
2666 | unsigned int interval_msecs) | |
2667 | { | |
249771b8 AE |
2668 | unsigned long elapsed = jiffies - *caller_jiffies; |
2669 | ||
2670 | if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) | |
2671 | return false; | |
2672 | ||
2673 | *caller_jiffies = jiffies; | |
2674 | return true; | |
f46c4833 AM |
2675 | } |
2676 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
2677 | |
2678 | static DEFINE_SPINLOCK(dump_list_lock); | |
2679 | static LIST_HEAD(dump_list); | |
2680 | ||
2681 | /** | |
2682 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 2683 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
2684 | * |
2685 | * Adds a kernel log dumper to the system. The dump callback in the | |
2686 | * structure will be called when the kernel oopses or panics and must be | |
2687 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
2688 | */ | |
2689 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
2690 | { | |
2691 | unsigned long flags; | |
2692 | int err = -EBUSY; | |
2693 | ||
2694 | /* The dump callback needs to be set */ | |
2695 | if (!dumper->dump) | |
2696 | return -EINVAL; | |
2697 | ||
2698 | spin_lock_irqsave(&dump_list_lock, flags); | |
2699 | /* Don't allow registering multiple times */ | |
2700 | if (!dumper->registered) { | |
2701 | dumper->registered = 1; | |
fb842b00 | 2702 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
2703 | err = 0; |
2704 | } | |
2705 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
2706 | ||
2707 | return err; | |
2708 | } | |
2709 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
2710 | ||
2711 | /** | |
2712 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 2713 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
2714 | * |
2715 | * Removes a dump device from the system. Returns zero on success and | |
2716 | * %-EINVAL otherwise. | |
2717 | */ | |
2718 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
2719 | { | |
2720 | unsigned long flags; | |
2721 | int err = -EINVAL; | |
2722 | ||
2723 | spin_lock_irqsave(&dump_list_lock, flags); | |
2724 | if (dumper->registered) { | |
2725 | dumper->registered = 0; | |
fb842b00 | 2726 | list_del_rcu(&dumper->list); |
456b565c SK |
2727 | err = 0; |
2728 | } | |
2729 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 2730 | synchronize_rcu(); |
456b565c SK |
2731 | |
2732 | return err; | |
2733 | } | |
2734 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
2735 | ||
7ff9554b KS |
2736 | static bool always_kmsg_dump; |
2737 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); | |
2738 | ||
456b565c SK |
2739 | /** |
2740 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
2741 | * @reason: the reason (oops, panic etc) for dumping | |
2742 | * | |
e2ae715d KS |
2743 | * Call each of the registered dumper's dump() callback, which can |
2744 | * retrieve the kmsg records with kmsg_dump_get_line() or | |
2745 | * kmsg_dump_get_buffer(). | |
456b565c SK |
2746 | */ |
2747 | void kmsg_dump(enum kmsg_dump_reason reason) | |
2748 | { | |
456b565c | 2749 | struct kmsg_dumper *dumper; |
456b565c SK |
2750 | unsigned long flags; |
2751 | ||
c22ab332 MG |
2752 | if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump) |
2753 | return; | |
2754 | ||
e2ae715d KS |
2755 | rcu_read_lock(); |
2756 | list_for_each_entry_rcu(dumper, &dump_list, list) { | |
2757 | if (dumper->max_reason && reason > dumper->max_reason) | |
2758 | continue; | |
2759 | ||
2760 | /* initialize iterator with data about the stored records */ | |
2761 | dumper->active = true; | |
2762 | ||
2763 | raw_spin_lock_irqsave(&logbuf_lock, flags); | |
2764 | dumper->cur_seq = clear_seq; | |
2765 | dumper->cur_idx = clear_idx; | |
2766 | dumper->next_seq = log_next_seq; | |
2767 | dumper->next_idx = log_next_idx; | |
2768 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); | |
2769 | ||
2770 | /* invoke dumper which will iterate over records */ | |
2771 | dumper->dump(dumper, reason); | |
2772 | ||
2773 | /* reset iterator */ | |
2774 | dumper->active = false; | |
2775 | } | |
2776 | rcu_read_unlock(); | |
2777 | } | |
2778 | ||
2779 | /** | |
533827c9 | 2780 | * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version) |
e2ae715d KS |
2781 | * @dumper: registered kmsg dumper |
2782 | * @syslog: include the "<4>" prefixes | |
2783 | * @line: buffer to copy the line to | |
2784 | * @size: maximum size of the buffer | |
2785 | * @len: length of line placed into buffer | |
2786 | * | |
2787 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
2788 | * record, and copy one record into the provided buffer. | |
2789 | * | |
2790 | * Consecutive calls will return the next available record moving | |
2791 | * towards the end of the buffer with the youngest messages. | |
2792 | * | |
2793 | * A return value of FALSE indicates that there are no more records to | |
2794 | * read. | |
533827c9 AV |
2795 | * |
2796 | * The function is similar to kmsg_dump_get_line(), but grabs no locks. | |
e2ae715d | 2797 | */ |
533827c9 AV |
2798 | bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog, |
2799 | char *line, size_t size, size_t *len) | |
e2ae715d | 2800 | { |
62e32ac3 | 2801 | struct printk_log *msg; |
e2ae715d KS |
2802 | size_t l = 0; |
2803 | bool ret = false; | |
2804 | ||
2805 | if (!dumper->active) | |
2806 | goto out; | |
7ff9554b | 2807 | |
e2ae715d KS |
2808 | if (dumper->cur_seq < log_first_seq) { |
2809 | /* messages are gone, move to first available one */ | |
2810 | dumper->cur_seq = log_first_seq; | |
2811 | dumper->cur_idx = log_first_idx; | |
2812 | } | |
456b565c | 2813 | |
e2ae715d | 2814 | /* last entry */ |
533827c9 | 2815 | if (dumper->cur_seq >= log_next_seq) |
e2ae715d | 2816 | goto out; |
456b565c | 2817 | |
e2ae715d | 2818 | msg = log_from_idx(dumper->cur_idx); |
5becfb1d | 2819 | l = msg_print_text(msg, 0, syslog, line, size); |
e2ae715d KS |
2820 | |
2821 | dumper->cur_idx = log_next(dumper->cur_idx); | |
2822 | dumper->cur_seq++; | |
2823 | ret = true; | |
e2ae715d KS |
2824 | out: |
2825 | if (len) | |
2826 | *len = l; | |
2827 | return ret; | |
2828 | } | |
533827c9 AV |
2829 | |
2830 | /** | |
2831 | * kmsg_dump_get_line - retrieve one kmsg log line | |
2832 | * @dumper: registered kmsg dumper | |
2833 | * @syslog: include the "<4>" prefixes | |
2834 | * @line: buffer to copy the line to | |
2835 | * @size: maximum size of the buffer | |
2836 | * @len: length of line placed into buffer | |
2837 | * | |
2838 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
2839 | * record, and copy one record into the provided buffer. | |
2840 | * | |
2841 | * Consecutive calls will return the next available record moving | |
2842 | * towards the end of the buffer with the youngest messages. | |
2843 | * | |
2844 | * A return value of FALSE indicates that there are no more records to | |
2845 | * read. | |
2846 | */ | |
2847 | bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, | |
2848 | char *line, size_t size, size_t *len) | |
2849 | { | |
2850 | unsigned long flags; | |
2851 | bool ret; | |
2852 | ||
2853 | raw_spin_lock_irqsave(&logbuf_lock, flags); | |
2854 | ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len); | |
2855 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); | |
2856 | ||
2857 | return ret; | |
2858 | } | |
e2ae715d KS |
2859 | EXPORT_SYMBOL_GPL(kmsg_dump_get_line); |
2860 | ||
2861 | /** | |
2862 | * kmsg_dump_get_buffer - copy kmsg log lines | |
2863 | * @dumper: registered kmsg dumper | |
2864 | * @syslog: include the "<4>" prefixes | |
4f0f4af5 | 2865 | * @buf: buffer to copy the line to |
e2ae715d KS |
2866 | * @size: maximum size of the buffer |
2867 | * @len: length of line placed into buffer | |
2868 | * | |
2869 | * Start at the end of the kmsg buffer and fill the provided buffer | |
2870 | * with as many of the the *youngest* kmsg records that fit into it. | |
2871 | * If the buffer is large enough, all available kmsg records will be | |
2872 | * copied with a single call. | |
2873 | * | |
2874 | * Consecutive calls will fill the buffer with the next block of | |
2875 | * available older records, not including the earlier retrieved ones. | |
2876 | * | |
2877 | * A return value of FALSE indicates that there are no more records to | |
2878 | * read. | |
2879 | */ | |
2880 | bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, | |
2881 | char *buf, size_t size, size_t *len) | |
2882 | { | |
2883 | unsigned long flags; | |
2884 | u64 seq; | |
2885 | u32 idx; | |
2886 | u64 next_seq; | |
2887 | u32 next_idx; | |
5becfb1d | 2888 | enum log_flags prev; |
e2ae715d KS |
2889 | size_t l = 0; |
2890 | bool ret = false; | |
2891 | ||
2892 | if (!dumper->active) | |
2893 | goto out; | |
2894 | ||
2895 | raw_spin_lock_irqsave(&logbuf_lock, flags); | |
2896 | if (dumper->cur_seq < log_first_seq) { | |
2897 | /* messages are gone, move to first available one */ | |
2898 | dumper->cur_seq = log_first_seq; | |
2899 | dumper->cur_idx = log_first_idx; | |
2900 | } | |
2901 | ||
2902 | /* last entry */ | |
2903 | if (dumper->cur_seq >= dumper->next_seq) { | |
2904 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); | |
2905 | goto out; | |
2906 | } | |
2907 | ||
2908 | /* calculate length of entire buffer */ | |
2909 | seq = dumper->cur_seq; | |
2910 | idx = dumper->cur_idx; | |
5becfb1d | 2911 | prev = 0; |
e2ae715d | 2912 | while (seq < dumper->next_seq) { |
62e32ac3 | 2913 | struct printk_log *msg = log_from_idx(idx); |
e2ae715d | 2914 | |
5becfb1d | 2915 | l += msg_print_text(msg, prev, true, NULL, 0); |
e2ae715d KS |
2916 | idx = log_next(idx); |
2917 | seq++; | |
5becfb1d | 2918 | prev = msg->flags; |
e2ae715d KS |
2919 | } |
2920 | ||
2921 | /* move first record forward until length fits into the buffer */ | |
2922 | seq = dumper->cur_seq; | |
2923 | idx = dumper->cur_idx; | |
5becfb1d | 2924 | prev = 0; |
e2ae715d | 2925 | while (l > size && seq < dumper->next_seq) { |
62e32ac3 | 2926 | struct printk_log *msg = log_from_idx(idx); |
456b565c | 2927 | |
5becfb1d | 2928 | l -= msg_print_text(msg, prev, true, NULL, 0); |
e2ae715d KS |
2929 | idx = log_next(idx); |
2930 | seq++; | |
5becfb1d | 2931 | prev = msg->flags; |
456b565c | 2932 | } |
e2ae715d KS |
2933 | |
2934 | /* last message in next interation */ | |
2935 | next_seq = seq; | |
2936 | next_idx = idx; | |
2937 | ||
2938 | l = 0; | |
2939 | while (seq < dumper->next_seq) { | |
62e32ac3 | 2940 | struct printk_log *msg = log_from_idx(idx); |
e2ae715d | 2941 | |
5becfb1d | 2942 | l += msg_print_text(msg, prev, syslog, buf + l, size - l); |
e2ae715d KS |
2943 | idx = log_next(idx); |
2944 | seq++; | |
5becfb1d | 2945 | prev = msg->flags; |
e2ae715d KS |
2946 | } |
2947 | ||
2948 | dumper->next_seq = next_seq; | |
2949 | dumper->next_idx = next_idx; | |
2950 | ret = true; | |
7ff9554b | 2951 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
e2ae715d KS |
2952 | out: |
2953 | if (len) | |
2954 | *len = l; | |
2955 | return ret; | |
2956 | } | |
2957 | EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); | |
456b565c | 2958 | |
533827c9 AV |
2959 | /** |
2960 | * kmsg_dump_rewind_nolock - reset the interator (unlocked version) | |
2961 | * @dumper: registered kmsg dumper | |
2962 | * | |
2963 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
2964 | * kmsg_dump_get_buffer() can be called again and used multiple | |
2965 | * times within the same dumper.dump() callback. | |
2966 | * | |
2967 | * The function is similar to kmsg_dump_rewind(), but grabs no locks. | |
2968 | */ | |
2969 | void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper) | |
2970 | { | |
2971 | dumper->cur_seq = clear_seq; | |
2972 | dumper->cur_idx = clear_idx; | |
2973 | dumper->next_seq = log_next_seq; | |
2974 | dumper->next_idx = log_next_idx; | |
2975 | } | |
2976 | ||
e2ae715d KS |
2977 | /** |
2978 | * kmsg_dump_rewind - reset the interator | |
2979 | * @dumper: registered kmsg dumper | |
2980 | * | |
2981 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
2982 | * kmsg_dump_get_buffer() can be called again and used multiple | |
2983 | * times within the same dumper.dump() callback. | |
2984 | */ | |
2985 | void kmsg_dump_rewind(struct kmsg_dumper *dumper) | |
2986 | { | |
2987 | unsigned long flags; | |
2988 | ||
2989 | raw_spin_lock_irqsave(&logbuf_lock, flags); | |
533827c9 | 2990 | kmsg_dump_rewind_nolock(dumper); |
e2ae715d | 2991 | raw_spin_unlock_irqrestore(&logbuf_lock, flags); |
456b565c | 2992 | } |
e2ae715d | 2993 | EXPORT_SYMBOL_GPL(kmsg_dump_rewind); |
196779b9 | 2994 | |
98e5e1bf TH |
2995 | static char dump_stack_arch_desc_str[128]; |
2996 | ||
2997 | /** | |
2998 | * dump_stack_set_arch_desc - set arch-specific str to show with task dumps | |
2999 | * @fmt: printf-style format string | |
3000 | * @...: arguments for the format string | |
3001 | * | |
3002 | * The configured string will be printed right after utsname during task | |
3003 | * dumps. Usually used to add arch-specific system identifiers. If an | |
3004 | * arch wants to make use of such an ID string, it should initialize this | |
3005 | * as soon as possible during boot. | |
3006 | */ | |
3007 | void __init dump_stack_set_arch_desc(const char *fmt, ...) | |
3008 | { | |
3009 | va_list args; | |
3010 | ||
3011 | va_start(args, fmt); | |
3012 | vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str), | |
3013 | fmt, args); | |
3014 | va_end(args); | |
3015 | } | |
3016 | ||
196779b9 TH |
3017 | /** |
3018 | * dump_stack_print_info - print generic debug info for dump_stack() | |
3019 | * @log_lvl: log level | |
3020 | * | |
3021 | * Arch-specific dump_stack() implementations can use this function to | |
3022 | * print out the same debug information as the generic dump_stack(). | |
3023 | */ | |
3024 | void dump_stack_print_info(const char *log_lvl) | |
3025 | { | |
3026 | printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n", | |
3027 | log_lvl, raw_smp_processor_id(), current->pid, current->comm, | |
3028 | print_tainted(), init_utsname()->release, | |
3029 | (int)strcspn(init_utsname()->version, " "), | |
3030 | init_utsname()->version); | |
98e5e1bf TH |
3031 | |
3032 | if (dump_stack_arch_desc_str[0] != '\0') | |
3033 | printk("%sHardware name: %s\n", | |
3034 | log_lvl, dump_stack_arch_desc_str); | |
3d1cb205 TH |
3035 | |
3036 | print_worker_info(log_lvl, current); | |
196779b9 TH |
3037 | } |
3038 | ||
a43cb95d TH |
3039 | /** |
3040 | * show_regs_print_info - print generic debug info for show_regs() | |
3041 | * @log_lvl: log level | |
3042 | * | |
3043 | * show_regs() implementations can use this function to print out generic | |
3044 | * debug information. | |
3045 | */ | |
3046 | void show_regs_print_info(const char *log_lvl) | |
3047 | { | |
3048 | dump_stack_print_info(log_lvl); | |
3049 | ||
3050 | printk("%stask: %p ti: %p task.ti: %p\n", | |
3051 | log_lvl, current, current_thread_info(), | |
3052 | task_thread_info(current)); | |
3053 | } | |
3054 | ||
7ef3d2fd | 3055 | #endif |