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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. | |
13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul | |
14 | * manfred@colorfullife.com | |
15 | * Rewrote bits to get rid of console_lock | |
16 | * 01Mar01 Andrew Morton | |
17 | */ | |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
23 | #include <linux/console.h> | |
24 | #include <linux/init.h> | |
25 | #include <linux/jiffies.h> | |
26 | #include <linux/nmi.h> | |
27 | #include <linux/module.h> | |
28 | #include <linux/moduleparam.h> | |
29 | #include <linux/delay.h> | |
30 | #include <linux/smp.h> | |
31 | #include <linux/security.h> | |
32 | #include <linux/bootmem.h> | |
33 | #include <linux/memblock.h> | |
34 | #include <linux/syscalls.h> | |
35 | #include <linux/crash_core.h> | |
36 | #include <linux/kdb.h> | |
37 | #include <linux/ratelimit.h> | |
38 | #include <linux/kmsg_dump.h> | |
39 | #include <linux/syslog.h> | |
40 | #include <linux/cpu.h> | |
41 | #include <linux/notifier.h> | |
42 | #include <linux/rculist.h> | |
43 | #include <linux/poll.h> | |
44 | #include <linux/irq_work.h> | |
45 | #include <linux/utsname.h> | |
46 | #include <linux/ctype.h> | |
47 | #include <linux/uio.h> | |
48 | #include <linux/sched/clock.h> | |
49 | #include <linux/sched/debug.h> | |
50 | #include <linux/sched/task_stack.h> | |
51 | ||
52 | #include <linux/uaccess.h> | |
53 | #include <asm/sections.h> | |
54 | ||
55 | #define CREATE_TRACE_POINTS | |
56 | #include <trace/events/printk.h> | |
57 | ||
58 | #include "console_cmdline.h" | |
59 | #include "braille.h" | |
60 | #include "internal.h" | |
61 | ||
62 | int console_printk[4] = { | |
63 | CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */ | |
64 | MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */ | |
65 | CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */ | |
66 | CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ | |
67 | }; | |
68 | ||
69 | /* | |
70 | * Low level drivers may need that to know if they can schedule in | |
71 | * their unblank() callback or not. So let's export it. | |
72 | */ | |
73 | int oops_in_progress; | |
74 | EXPORT_SYMBOL(oops_in_progress); | |
75 | ||
76 | /* | |
77 | * console_sem protects the console_drivers list, and also | |
78 | * provides serialisation for access to the entire console | |
79 | * driver system. | |
80 | */ | |
81 | static DEFINE_SEMAPHORE(console_sem); | |
82 | struct console *console_drivers; | |
83 | EXPORT_SYMBOL_GPL(console_drivers); | |
84 | ||
85 | #ifdef CONFIG_LOCKDEP | |
86 | static struct lockdep_map console_lock_dep_map = { | |
87 | .name = "console_lock" | |
88 | }; | |
89 | #endif | |
90 | ||
91 | enum devkmsg_log_bits { | |
92 | __DEVKMSG_LOG_BIT_ON = 0, | |
93 | __DEVKMSG_LOG_BIT_OFF, | |
94 | __DEVKMSG_LOG_BIT_LOCK, | |
95 | }; | |
96 | ||
97 | enum devkmsg_log_masks { | |
98 | DEVKMSG_LOG_MASK_ON = BIT(__DEVKMSG_LOG_BIT_ON), | |
99 | DEVKMSG_LOG_MASK_OFF = BIT(__DEVKMSG_LOG_BIT_OFF), | |
100 | DEVKMSG_LOG_MASK_LOCK = BIT(__DEVKMSG_LOG_BIT_LOCK), | |
101 | }; | |
102 | ||
103 | /* Keep both the 'on' and 'off' bits clear, i.e. ratelimit by default: */ | |
104 | #define DEVKMSG_LOG_MASK_DEFAULT 0 | |
105 | ||
106 | static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; | |
107 | ||
108 | static int __control_devkmsg(char *str) | |
109 | { | |
110 | if (!str) | |
111 | return -EINVAL; | |
112 | ||
113 | if (!strncmp(str, "on", 2)) { | |
114 | devkmsg_log = DEVKMSG_LOG_MASK_ON; | |
115 | return 2; | |
116 | } else if (!strncmp(str, "off", 3)) { | |
117 | devkmsg_log = DEVKMSG_LOG_MASK_OFF; | |
118 | return 3; | |
119 | } else if (!strncmp(str, "ratelimit", 9)) { | |
120 | devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; | |
121 | return 9; | |
122 | } | |
123 | return -EINVAL; | |
124 | } | |
125 | ||
126 | static int __init control_devkmsg(char *str) | |
127 | { | |
128 | if (__control_devkmsg(str) < 0) | |
129 | return 1; | |
130 | ||
131 | /* | |
132 | * Set sysctl string accordingly: | |
133 | */ | |
134 | if (devkmsg_log == DEVKMSG_LOG_MASK_ON) { | |
135 | memset(devkmsg_log_str, 0, DEVKMSG_STR_MAX_SIZE); | |
136 | strncpy(devkmsg_log_str, "on", 2); | |
137 | } else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF) { | |
138 | memset(devkmsg_log_str, 0, DEVKMSG_STR_MAX_SIZE); | |
139 | strncpy(devkmsg_log_str, "off", 3); | |
140 | } | |
141 | /* else "ratelimit" which is set by default. */ | |
142 | ||
143 | /* | |
144 | * Sysctl cannot change it anymore. The kernel command line setting of | |
145 | * this parameter is to force the setting to be permanent throughout the | |
146 | * runtime of the system. This is a precation measure against userspace | |
147 | * trying to be a smarta** and attempting to change it up on us. | |
148 | */ | |
149 | devkmsg_log |= DEVKMSG_LOG_MASK_LOCK; | |
150 | ||
151 | return 0; | |
152 | } | |
153 | __setup("printk.devkmsg=", control_devkmsg); | |
154 | ||
155 | char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit"; | |
156 | ||
157 | int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, | |
158 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
159 | { | |
160 | char old_str[DEVKMSG_STR_MAX_SIZE]; | |
161 | unsigned int old; | |
162 | int err; | |
163 | ||
164 | if (write) { | |
165 | if (devkmsg_log & DEVKMSG_LOG_MASK_LOCK) | |
166 | return -EINVAL; | |
167 | ||
168 | old = devkmsg_log; | |
169 | strncpy(old_str, devkmsg_log_str, DEVKMSG_STR_MAX_SIZE); | |
170 | } | |
171 | ||
172 | err = proc_dostring(table, write, buffer, lenp, ppos); | |
173 | if (err) | |
174 | return err; | |
175 | ||
176 | if (write) { | |
177 | err = __control_devkmsg(devkmsg_log_str); | |
178 | ||
179 | /* | |
180 | * Do not accept an unknown string OR a known string with | |
181 | * trailing crap... | |
182 | */ | |
183 | if (err < 0 || (err + 1 != *lenp)) { | |
184 | ||
185 | /* ... and restore old setting. */ | |
186 | devkmsg_log = old; | |
187 | strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE); | |
188 | ||
189 | return -EINVAL; | |
190 | } | |
191 | } | |
192 | ||
193 | return 0; | |
194 | } | |
195 | ||
196 | /* | |
197 | * Number of registered extended console drivers. | |
198 | * | |
199 | * If extended consoles are present, in-kernel cont reassembly is disabled | |
200 | * and each fragment is stored as a separate log entry with proper | |
201 | * continuation flag so that every emitted message has full metadata. This | |
202 | * doesn't change the result for regular consoles or /proc/kmsg. For | |
203 | * /dev/kmsg, as long as the reader concatenates messages according to | |
204 | * consecutive continuation flags, the end result should be the same too. | |
205 | */ | |
206 | static int nr_ext_console_drivers; | |
207 | ||
208 | /* | |
209 | * Helper macros to handle lockdep when locking/unlocking console_sem. We use | |
210 | * macros instead of functions so that _RET_IP_ contains useful information. | |
211 | */ | |
212 | #define down_console_sem() do { \ | |
213 | down(&console_sem);\ | |
214 | mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ | |
215 | } while (0) | |
216 | ||
217 | static int __down_trylock_console_sem(unsigned long ip) | |
218 | { | |
219 | int lock_failed; | |
220 | unsigned long flags; | |
221 | ||
222 | /* | |
223 | * Here and in __up_console_sem() we need to be in safe mode, | |
224 | * because spindump/WARN/etc from under console ->lock will | |
225 | * deadlock in printk()->down_trylock_console_sem() otherwise. | |
226 | */ | |
227 | printk_safe_enter_irqsave(flags); | |
228 | lock_failed = down_trylock(&console_sem); | |
229 | printk_safe_exit_irqrestore(flags); | |
230 | ||
231 | if (lock_failed) | |
232 | return 1; | |
233 | mutex_acquire(&console_lock_dep_map, 0, 1, ip); | |
234 | return 0; | |
235 | } | |
236 | #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) | |
237 | ||
238 | static void __up_console_sem(unsigned long ip) | |
239 | { | |
240 | unsigned long flags; | |
241 | ||
242 | mutex_release(&console_lock_dep_map, 1, ip); | |
243 | ||
244 | printk_safe_enter_irqsave(flags); | |
245 | up(&console_sem); | |
246 | printk_safe_exit_irqrestore(flags); | |
247 | } | |
248 | #define up_console_sem() __up_console_sem(_RET_IP_) | |
249 | ||
250 | /* | |
251 | * This is used for debugging the mess that is the VT code by | |
252 | * keeping track if we have the console semaphore held. It's | |
253 | * definitely not the perfect debug tool (we don't know if _WE_ | |
254 | * hold it and are racing, but it helps tracking those weird code | |
255 | * paths in the console code where we end up in places I want | |
256 | * locked without the console sempahore held). | |
257 | */ | |
258 | static int console_locked, console_suspended; | |
259 | ||
260 | /* | |
261 | * If exclusive_console is non-NULL then only this console is to be printed to. | |
262 | */ | |
263 | static struct console *exclusive_console; | |
264 | ||
265 | /* | |
266 | * Array of consoles built from command line options (console=) | |
267 | */ | |
268 | ||
269 | #define MAX_CMDLINECONSOLES 8 | |
270 | ||
271 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
272 | ||
273 | static int preferred_console = -1; | |
274 | int console_set_on_cmdline; | |
275 | EXPORT_SYMBOL(console_set_on_cmdline); | |
276 | ||
277 | /* Flag: console code may call schedule() */ | |
278 | static int console_may_schedule; | |
279 | ||
280 | /* | |
281 | * The printk log buffer consists of a chain of concatenated variable | |
282 | * length records. Every record starts with a record header, containing | |
283 | * the overall length of the record. | |
284 | * | |
285 | * The heads to the first and last entry in the buffer, as well as the | |
286 | * sequence numbers of these entries are maintained when messages are | |
287 | * stored. | |
288 | * | |
289 | * If the heads indicate available messages, the length in the header | |
290 | * tells the start next message. A length == 0 for the next message | |
291 | * indicates a wrap-around to the beginning of the buffer. | |
292 | * | |
293 | * Every record carries the monotonic timestamp in microseconds, as well as | |
294 | * the standard userspace syslog level and syslog facility. The usual | |
295 | * kernel messages use LOG_KERN; userspace-injected messages always carry | |
296 | * a matching syslog facility, by default LOG_USER. The origin of every | |
297 | * message can be reliably determined that way. | |
298 | * | |
299 | * The human readable log message directly follows the message header. The | |
300 | * length of the message text is stored in the header, the stored message | |
301 | * is not terminated. | |
302 | * | |
303 | * Optionally, a message can carry a dictionary of properties (key/value pairs), | |
304 | * to provide userspace with a machine-readable message context. | |
305 | * | |
306 | * Examples for well-defined, commonly used property names are: | |
307 | * DEVICE=b12:8 device identifier | |
308 | * b12:8 block dev_t | |
309 | * c127:3 char dev_t | |
310 | * n8 netdev ifindex | |
311 | * +sound:card0 subsystem:devname | |
312 | * SUBSYSTEM=pci driver-core subsystem name | |
313 | * | |
314 | * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value | |
315 | * follows directly after a '=' character. Every property is terminated by | |
316 | * a '\0' character. The last property is not terminated. | |
317 | * | |
318 | * Example of a message structure: | |
319 | * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec | |
320 | * 0008 34 00 record is 52 bytes long | |
321 | * 000a 0b 00 text is 11 bytes long | |
322 | * 000c 1f 00 dictionary is 23 bytes long | |
323 | * 000e 03 00 LOG_KERN (facility) LOG_ERR (level) | |
324 | * 0010 69 74 27 73 20 61 20 6c "it's a l" | |
325 | * 69 6e 65 "ine" | |
326 | * 001b 44 45 56 49 43 "DEVIC" | |
327 | * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D" | |
328 | * 52 49 56 45 52 3d 62 75 "RIVER=bu" | |
329 | * 67 "g" | |
330 | * 0032 00 00 00 padding to next message header | |
331 | * | |
332 | * The 'struct printk_log' buffer header must never be directly exported to | |
333 | * userspace, it is a kernel-private implementation detail that might | |
334 | * need to be changed in the future, when the requirements change. | |
335 | * | |
336 | * /dev/kmsg exports the structured data in the following line format: | |
337 | * "<level>,<sequnum>,<timestamp>,<contflag>[,additional_values, ... ];<message text>\n" | |
338 | * | |
339 | * Users of the export format should ignore possible additional values | |
340 | * separated by ',', and find the message after the ';' character. | |
341 | * | |
342 | * The optional key/value pairs are attached as continuation lines starting | |
343 | * with a space character and terminated by a newline. All possible | |
344 | * non-prinatable characters are escaped in the "\xff" notation. | |
345 | */ | |
346 | ||
347 | enum log_flags { | |
348 | LOG_NOCONS = 1, /* already flushed, do not print to console */ | |
349 | LOG_NEWLINE = 2, /* text ended with a newline */ | |
350 | LOG_PREFIX = 4, /* text started with a prefix */ | |
351 | LOG_CONT = 8, /* text is a fragment of a continuation line */ | |
352 | }; | |
353 | ||
354 | struct printk_log { | |
355 | u64 ts_nsec; /* timestamp in nanoseconds */ | |
356 | u16 len; /* length of entire record */ | |
357 | u16 text_len; /* length of text buffer */ | |
358 | u16 dict_len; /* length of dictionary buffer */ | |
359 | u8 facility; /* syslog facility */ | |
360 | u8 flags:5; /* internal record flags */ | |
361 | u8 level:3; /* syslog level */ | |
362 | } | |
363 | #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS | |
364 | __packed __aligned(4) | |
365 | #endif | |
366 | ; | |
367 | ||
368 | /* | |
369 | * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken | |
370 | * within the scheduler's rq lock. It must be released before calling | |
371 | * console_unlock() or anything else that might wake up a process. | |
372 | */ | |
373 | DEFINE_RAW_SPINLOCK(logbuf_lock); | |
374 | ||
375 | /* | |
376 | * Helper macros to lock/unlock logbuf_lock and switch between | |
377 | * printk-safe/unsafe modes. | |
378 | */ | |
379 | #define logbuf_lock_irq() \ | |
380 | do { \ | |
381 | printk_safe_enter_irq(); \ | |
382 | raw_spin_lock(&logbuf_lock); \ | |
383 | } while (0) | |
384 | ||
385 | #define logbuf_unlock_irq() \ | |
386 | do { \ | |
387 | raw_spin_unlock(&logbuf_lock); \ | |
388 | printk_safe_exit_irq(); \ | |
389 | } while (0) | |
390 | ||
391 | #define logbuf_lock_irqsave(flags) \ | |
392 | do { \ | |
393 | printk_safe_enter_irqsave(flags); \ | |
394 | raw_spin_lock(&logbuf_lock); \ | |
395 | } while (0) | |
396 | ||
397 | #define logbuf_unlock_irqrestore(flags) \ | |
398 | do { \ | |
399 | raw_spin_unlock(&logbuf_lock); \ | |
400 | printk_safe_exit_irqrestore(flags); \ | |
401 | } while (0) | |
402 | ||
403 | #ifdef CONFIG_PRINTK | |
404 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
405 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ | |
406 | static u64 syslog_seq; | |
407 | static u32 syslog_idx; | |
408 | static size_t syslog_partial; | |
409 | ||
410 | /* index and sequence number of the first record stored in the buffer */ | |
411 | static u64 log_first_seq; | |
412 | static u32 log_first_idx; | |
413 | ||
414 | /* index and sequence number of the next record to store in the buffer */ | |
415 | static u64 log_next_seq; | |
416 | static u32 log_next_idx; | |
417 | ||
418 | /* the next printk record to write to the console */ | |
419 | static u64 console_seq; | |
420 | static u32 console_idx; | |
421 | ||
422 | /* the next printk record to read after the last 'clear' command */ | |
423 | static u64 clear_seq; | |
424 | static u32 clear_idx; | |
425 | ||
426 | #define PREFIX_MAX 32 | |
427 | #define LOG_LINE_MAX (1024 - PREFIX_MAX) | |
428 | ||
429 | #define LOG_LEVEL(v) ((v) & 0x07) | |
430 | #define LOG_FACILITY(v) ((v) >> 3 & 0xff) | |
431 | ||
432 | /* record buffer */ | |
433 | #define LOG_ALIGN __alignof__(struct printk_log) | |
434 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) | |
435 | static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); | |
436 | static char *log_buf = __log_buf; | |
437 | static u32 log_buf_len = __LOG_BUF_LEN; | |
438 | ||
439 | /* Return log buffer address */ | |
440 | char *log_buf_addr_get(void) | |
441 | { | |
442 | return log_buf; | |
443 | } | |
444 | ||
445 | /* Return log buffer size */ | |
446 | u32 log_buf_len_get(void) | |
447 | { | |
448 | return log_buf_len; | |
449 | } | |
450 | ||
451 | /* human readable text of the record */ | |
452 | static char *log_text(const struct printk_log *msg) | |
453 | { | |
454 | return (char *)msg + sizeof(struct printk_log); | |
455 | } | |
456 | ||
457 | /* optional key/value pair dictionary attached to the record */ | |
458 | static char *log_dict(const struct printk_log *msg) | |
459 | { | |
460 | return (char *)msg + sizeof(struct printk_log) + msg->text_len; | |
461 | } | |
462 | ||
463 | /* get record by index; idx must point to valid msg */ | |
464 | static struct printk_log *log_from_idx(u32 idx) | |
465 | { | |
466 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); | |
467 | ||
468 | /* | |
469 | * A length == 0 record is the end of buffer marker. Wrap around and | |
470 | * read the message at the start of the buffer. | |
471 | */ | |
472 | if (!msg->len) | |
473 | return (struct printk_log *)log_buf; | |
474 | return msg; | |
475 | } | |
476 | ||
477 | /* get next record; idx must point to valid msg */ | |
478 | static u32 log_next(u32 idx) | |
479 | { | |
480 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); | |
481 | ||
482 | /* length == 0 indicates the end of the buffer; wrap */ | |
483 | /* | |
484 | * A length == 0 record is the end of buffer marker. Wrap around and | |
485 | * read the message at the start of the buffer as *this* one, and | |
486 | * return the one after that. | |
487 | */ | |
488 | if (!msg->len) { | |
489 | msg = (struct printk_log *)log_buf; | |
490 | return msg->len; | |
491 | } | |
492 | return idx + msg->len; | |
493 | } | |
494 | ||
495 | /* | |
496 | * Check whether there is enough free space for the given message. | |
497 | * | |
498 | * The same values of first_idx and next_idx mean that the buffer | |
499 | * is either empty or full. | |
500 | * | |
501 | * If the buffer is empty, we must respect the position of the indexes. | |
502 | * They cannot be reset to the beginning of the buffer. | |
503 | */ | |
504 | static int logbuf_has_space(u32 msg_size, bool empty) | |
505 | { | |
506 | u32 free; | |
507 | ||
508 | if (log_next_idx > log_first_idx || empty) | |
509 | free = max(log_buf_len - log_next_idx, log_first_idx); | |
510 | else | |
511 | free = log_first_idx - log_next_idx; | |
512 | ||
513 | /* | |
514 | * We need space also for an empty header that signalizes wrapping | |
515 | * of the buffer. | |
516 | */ | |
517 | return free >= msg_size + sizeof(struct printk_log); | |
518 | } | |
519 | ||
520 | static int log_make_free_space(u32 msg_size) | |
521 | { | |
522 | while (log_first_seq < log_next_seq && | |
523 | !logbuf_has_space(msg_size, false)) { | |
524 | /* drop old messages until we have enough contiguous space */ | |
525 | log_first_idx = log_next(log_first_idx); | |
526 | log_first_seq++; | |
527 | } | |
528 | ||
529 | if (clear_seq < log_first_seq) { | |
530 | clear_seq = log_first_seq; | |
531 | clear_idx = log_first_idx; | |
532 | } | |
533 | ||
534 | /* sequence numbers are equal, so the log buffer is empty */ | |
535 | if (logbuf_has_space(msg_size, log_first_seq == log_next_seq)) | |
536 | return 0; | |
537 | ||
538 | return -ENOMEM; | |
539 | } | |
540 | ||
541 | /* compute the message size including the padding bytes */ | |
542 | static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len) | |
543 | { | |
544 | u32 size; | |
545 | ||
546 | size = sizeof(struct printk_log) + text_len + dict_len; | |
547 | *pad_len = (-size) & (LOG_ALIGN - 1); | |
548 | size += *pad_len; | |
549 | ||
550 | return size; | |
551 | } | |
552 | ||
553 | /* | |
554 | * Define how much of the log buffer we could take at maximum. The value | |
555 | * must be greater than two. Note that only half of the buffer is available | |
556 | * when the index points to the middle. | |
557 | */ | |
558 | #define MAX_LOG_TAKE_PART 4 | |
559 | static const char trunc_msg[] = "<truncated>"; | |
560 | ||
561 | static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len, | |
562 | u16 *dict_len, u32 *pad_len) | |
563 | { | |
564 | /* | |
565 | * The message should not take the whole buffer. Otherwise, it might | |
566 | * get removed too soon. | |
567 | */ | |
568 | u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART; | |
569 | if (*text_len > max_text_len) | |
570 | *text_len = max_text_len; | |
571 | /* enable the warning message */ | |
572 | *trunc_msg_len = strlen(trunc_msg); | |
573 | /* disable the "dict" completely */ | |
574 | *dict_len = 0; | |
575 | /* compute the size again, count also the warning message */ | |
576 | return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len); | |
577 | } | |
578 | ||
579 | /* insert record into the buffer, discard old ones, update heads */ | |
580 | static int log_store(int facility, int level, | |
581 | enum log_flags flags, u64 ts_nsec, | |
582 | const char *dict, u16 dict_len, | |
583 | const char *text, u16 text_len) | |
584 | { | |
585 | struct printk_log *msg; | |
586 | u32 size, pad_len; | |
587 | u16 trunc_msg_len = 0; | |
588 | ||
589 | /* number of '\0' padding bytes to next message */ | |
590 | size = msg_used_size(text_len, dict_len, &pad_len); | |
591 | ||
592 | if (log_make_free_space(size)) { | |
593 | /* truncate the message if it is too long for empty buffer */ | |
594 | size = truncate_msg(&text_len, &trunc_msg_len, | |
595 | &dict_len, &pad_len); | |
596 | /* survive when the log buffer is too small for trunc_msg */ | |
597 | if (log_make_free_space(size)) | |
598 | return 0; | |
599 | } | |
600 | ||
601 | if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) { | |
602 | /* | |
603 | * This message + an additional empty header does not fit | |
604 | * at the end of the buffer. Add an empty header with len == 0 | |
605 | * to signify a wrap around. | |
606 | */ | |
607 | memset(log_buf + log_next_idx, 0, sizeof(struct printk_log)); | |
608 | log_next_idx = 0; | |
609 | } | |
610 | ||
611 | /* fill message */ | |
612 | msg = (struct printk_log *)(log_buf + log_next_idx); | |
613 | memcpy(log_text(msg), text, text_len); | |
614 | msg->text_len = text_len; | |
615 | if (trunc_msg_len) { | |
616 | memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len); | |
617 | msg->text_len += trunc_msg_len; | |
618 | } | |
619 | memcpy(log_dict(msg), dict, dict_len); | |
620 | msg->dict_len = dict_len; | |
621 | msg->facility = facility; | |
622 | msg->level = level & 7; | |
623 | msg->flags = flags & 0x1f; | |
624 | if (ts_nsec > 0) | |
625 | msg->ts_nsec = ts_nsec; | |
626 | else | |
627 | msg->ts_nsec = local_clock(); | |
628 | memset(log_dict(msg) + dict_len, 0, pad_len); | |
629 | msg->len = size; | |
630 | ||
631 | /* insert message */ | |
632 | log_next_idx += msg->len; | |
633 | log_next_seq++; | |
634 | ||
635 | return msg->text_len; | |
636 | } | |
637 | ||
638 | int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); | |
639 | ||
640 | static int syslog_action_restricted(int type) | |
641 | { | |
642 | if (dmesg_restrict) | |
643 | return 1; | |
644 | /* | |
645 | * Unless restricted, we allow "read all" and "get buffer size" | |
646 | * for everybody. | |
647 | */ | |
648 | return type != SYSLOG_ACTION_READ_ALL && | |
649 | type != SYSLOG_ACTION_SIZE_BUFFER; | |
650 | } | |
651 | ||
652 | int check_syslog_permissions(int type, int source) | |
653 | { | |
654 | /* | |
655 | * If this is from /proc/kmsg and we've already opened it, then we've | |
656 | * already done the capabilities checks at open time. | |
657 | */ | |
658 | if (source == SYSLOG_FROM_PROC && type != SYSLOG_ACTION_OPEN) | |
659 | goto ok; | |
660 | ||
661 | if (syslog_action_restricted(type)) { | |
662 | if (capable(CAP_SYSLOG)) | |
663 | goto ok; | |
664 | /* | |
665 | * For historical reasons, accept CAP_SYS_ADMIN too, with | |
666 | * a warning. | |
667 | */ | |
668 | if (capable(CAP_SYS_ADMIN)) { | |
669 | pr_warn_once("%s (%d): Attempt to access syslog with " | |
670 | "CAP_SYS_ADMIN but no CAP_SYSLOG " | |
671 | "(deprecated).\n", | |
672 | current->comm, task_pid_nr(current)); | |
673 | goto ok; | |
674 | } | |
675 | return -EPERM; | |
676 | } | |
677 | ok: | |
678 | return security_syslog(type); | |
679 | } | |
680 | EXPORT_SYMBOL_GPL(check_syslog_permissions); | |
681 | ||
682 | static void append_char(char **pp, char *e, char c) | |
683 | { | |
684 | if (*pp < e) | |
685 | *(*pp)++ = c; | |
686 | } | |
687 | ||
688 | static ssize_t msg_print_ext_header(char *buf, size_t size, | |
689 | struct printk_log *msg, u64 seq) | |
690 | { | |
691 | u64 ts_usec = msg->ts_nsec; | |
692 | ||
693 | do_div(ts_usec, 1000); | |
694 | ||
695 | return scnprintf(buf, size, "%u,%llu,%llu,%c;", | |
696 | (msg->facility << 3) | msg->level, seq, ts_usec, | |
697 | msg->flags & LOG_CONT ? 'c' : '-'); | |
698 | } | |
699 | ||
700 | static ssize_t msg_print_ext_body(char *buf, size_t size, | |
701 | char *dict, size_t dict_len, | |
702 | char *text, size_t text_len) | |
703 | { | |
704 | char *p = buf, *e = buf + size; | |
705 | size_t i; | |
706 | ||
707 | /* escape non-printable characters */ | |
708 | for (i = 0; i < text_len; i++) { | |
709 | unsigned char c = text[i]; | |
710 | ||
711 | if (c < ' ' || c >= 127 || c == '\\') | |
712 | p += scnprintf(p, e - p, "\\x%02x", c); | |
713 | else | |
714 | append_char(&p, e, c); | |
715 | } | |
716 | append_char(&p, e, '\n'); | |
717 | ||
718 | if (dict_len) { | |
719 | bool line = true; | |
720 | ||
721 | for (i = 0; i < dict_len; i++) { | |
722 | unsigned char c = dict[i]; | |
723 | ||
724 | if (line) { | |
725 | append_char(&p, e, ' '); | |
726 | line = false; | |
727 | } | |
728 | ||
729 | if (c == '\0') { | |
730 | append_char(&p, e, '\n'); | |
731 | line = true; | |
732 | continue; | |
733 | } | |
734 | ||
735 | if (c < ' ' || c >= 127 || c == '\\') { | |
736 | p += scnprintf(p, e - p, "\\x%02x", c); | |
737 | continue; | |
738 | } | |
739 | ||
740 | append_char(&p, e, c); | |
741 | } | |
742 | append_char(&p, e, '\n'); | |
743 | } | |
744 | ||
745 | return p - buf; | |
746 | } | |
747 | ||
748 | /* /dev/kmsg - userspace message inject/listen interface */ | |
749 | struct devkmsg_user { | |
750 | u64 seq; | |
751 | u32 idx; | |
752 | struct ratelimit_state rs; | |
753 | struct mutex lock; | |
754 | char buf[CONSOLE_EXT_LOG_MAX]; | |
755 | }; | |
756 | ||
757 | static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from) | |
758 | { | |
759 | char *buf, *line; | |
760 | int level = default_message_loglevel; | |
761 | int facility = 1; /* LOG_USER */ | |
762 | struct file *file = iocb->ki_filp; | |
763 | struct devkmsg_user *user = file->private_data; | |
764 | size_t len = iov_iter_count(from); | |
765 | ssize_t ret = len; | |
766 | ||
767 | if (!user || len > LOG_LINE_MAX) | |
768 | return -EINVAL; | |
769 | ||
770 | /* Ignore when user logging is disabled. */ | |
771 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) | |
772 | return len; | |
773 | ||
774 | /* Ratelimit when not explicitly enabled. */ | |
775 | if (!(devkmsg_log & DEVKMSG_LOG_MASK_ON)) { | |
776 | if (!___ratelimit(&user->rs, current->comm)) | |
777 | return ret; | |
778 | } | |
779 | ||
780 | buf = kmalloc(len+1, GFP_KERNEL); | |
781 | if (buf == NULL) | |
782 | return -ENOMEM; | |
783 | ||
784 | buf[len] = '\0'; | |
785 | if (!copy_from_iter_full(buf, len, from)) { | |
786 | kfree(buf); | |
787 | return -EFAULT; | |
788 | } | |
789 | ||
790 | /* | |
791 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace | |
792 | * the decimal value represents 32bit, the lower 3 bit are the log | |
793 | * level, the rest are the log facility. | |
794 | * | |
795 | * If no prefix or no userspace facility is specified, we | |
796 | * enforce LOG_USER, to be able to reliably distinguish | |
797 | * kernel-generated messages from userspace-injected ones. | |
798 | */ | |
799 | line = buf; | |
800 | if (line[0] == '<') { | |
801 | char *endp = NULL; | |
802 | unsigned int u; | |
803 | ||
804 | u = simple_strtoul(line + 1, &endp, 10); | |
805 | if (endp && endp[0] == '>') { | |
806 | level = LOG_LEVEL(u); | |
807 | if (LOG_FACILITY(u) != 0) | |
808 | facility = LOG_FACILITY(u); | |
809 | endp++; | |
810 | len -= endp - line; | |
811 | line = endp; | |
812 | } | |
813 | } | |
814 | ||
815 | printk_emit(facility, level, NULL, 0, "%s", line); | |
816 | kfree(buf); | |
817 | return ret; | |
818 | } | |
819 | ||
820 | static ssize_t devkmsg_read(struct file *file, char __user *buf, | |
821 | size_t count, loff_t *ppos) | |
822 | { | |
823 | struct devkmsg_user *user = file->private_data; | |
824 | struct printk_log *msg; | |
825 | size_t len; | |
826 | ssize_t ret; | |
827 | ||
828 | if (!user) | |
829 | return -EBADF; | |
830 | ||
831 | ret = mutex_lock_interruptible(&user->lock); | |
832 | if (ret) | |
833 | return ret; | |
834 | ||
835 | logbuf_lock_irq(); | |
836 | while (user->seq == log_next_seq) { | |
837 | if (file->f_flags & O_NONBLOCK) { | |
838 | ret = -EAGAIN; | |
839 | logbuf_unlock_irq(); | |
840 | goto out; | |
841 | } | |
842 | ||
843 | logbuf_unlock_irq(); | |
844 | ret = wait_event_interruptible(log_wait, | |
845 | user->seq != log_next_seq); | |
846 | if (ret) | |
847 | goto out; | |
848 | logbuf_lock_irq(); | |
849 | } | |
850 | ||
851 | if (user->seq < log_first_seq) { | |
852 | /* our last seen message is gone, return error and reset */ | |
853 | user->idx = log_first_idx; | |
854 | user->seq = log_first_seq; | |
855 | ret = -EPIPE; | |
856 | logbuf_unlock_irq(); | |
857 | goto out; | |
858 | } | |
859 | ||
860 | msg = log_from_idx(user->idx); | |
861 | len = msg_print_ext_header(user->buf, sizeof(user->buf), | |
862 | msg, user->seq); | |
863 | len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len, | |
864 | log_dict(msg), msg->dict_len, | |
865 | log_text(msg), msg->text_len); | |
866 | ||
867 | user->idx = log_next(user->idx); | |
868 | user->seq++; | |
869 | logbuf_unlock_irq(); | |
870 | ||
871 | if (len > count) { | |
872 | ret = -EINVAL; | |
873 | goto out; | |
874 | } | |
875 | ||
876 | if (copy_to_user(buf, user->buf, len)) { | |
877 | ret = -EFAULT; | |
878 | goto out; | |
879 | } | |
880 | ret = len; | |
881 | out: | |
882 | mutex_unlock(&user->lock); | |
883 | return ret; | |
884 | } | |
885 | ||
886 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) | |
887 | { | |
888 | struct devkmsg_user *user = file->private_data; | |
889 | loff_t ret = 0; | |
890 | ||
891 | if (!user) | |
892 | return -EBADF; | |
893 | if (offset) | |
894 | return -ESPIPE; | |
895 | ||
896 | logbuf_lock_irq(); | |
897 | switch (whence) { | |
898 | case SEEK_SET: | |
899 | /* the first record */ | |
900 | user->idx = log_first_idx; | |
901 | user->seq = log_first_seq; | |
902 | break; | |
903 | case SEEK_DATA: | |
904 | /* | |
905 | * The first record after the last SYSLOG_ACTION_CLEAR, | |
906 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself | |
907 | * changes no global state, and does not clear anything. | |
908 | */ | |
909 | user->idx = clear_idx; | |
910 | user->seq = clear_seq; | |
911 | break; | |
912 | case SEEK_END: | |
913 | /* after the last record */ | |
914 | user->idx = log_next_idx; | |
915 | user->seq = log_next_seq; | |
916 | break; | |
917 | default: | |
918 | ret = -EINVAL; | |
919 | } | |
920 | logbuf_unlock_irq(); | |
921 | return ret; | |
922 | } | |
923 | ||
924 | static unsigned int devkmsg_poll(struct file *file, poll_table *wait) | |
925 | { | |
926 | struct devkmsg_user *user = file->private_data; | |
927 | int ret = 0; | |
928 | ||
929 | if (!user) | |
930 | return POLLERR|POLLNVAL; | |
931 | ||
932 | poll_wait(file, &log_wait, wait); | |
933 | ||
934 | logbuf_lock_irq(); | |
935 | if (user->seq < log_next_seq) { | |
936 | /* return error when data has vanished underneath us */ | |
937 | if (user->seq < log_first_seq) | |
938 | ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI; | |
939 | else | |
940 | ret = POLLIN|POLLRDNORM; | |
941 | } | |
942 | logbuf_unlock_irq(); | |
943 | ||
944 | return ret; | |
945 | } | |
946 | ||
947 | static int devkmsg_open(struct inode *inode, struct file *file) | |
948 | { | |
949 | struct devkmsg_user *user; | |
950 | int err; | |
951 | ||
952 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) | |
953 | return -EPERM; | |
954 | ||
955 | /* write-only does not need any file context */ | |
956 | if ((file->f_flags & O_ACCMODE) != O_WRONLY) { | |
957 | err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, | |
958 | SYSLOG_FROM_READER); | |
959 | if (err) | |
960 | return err; | |
961 | } | |
962 | ||
963 | user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); | |
964 | if (!user) | |
965 | return -ENOMEM; | |
966 | ||
967 | ratelimit_default_init(&user->rs); | |
968 | ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE); | |
969 | ||
970 | mutex_init(&user->lock); | |
971 | ||
972 | logbuf_lock_irq(); | |
973 | user->idx = log_first_idx; | |
974 | user->seq = log_first_seq; | |
975 | logbuf_unlock_irq(); | |
976 | ||
977 | file->private_data = user; | |
978 | return 0; | |
979 | } | |
980 | ||
981 | static int devkmsg_release(struct inode *inode, struct file *file) | |
982 | { | |
983 | struct devkmsg_user *user = file->private_data; | |
984 | ||
985 | if (!user) | |
986 | return 0; | |
987 | ||
988 | ratelimit_state_exit(&user->rs); | |
989 | ||
990 | mutex_destroy(&user->lock); | |
991 | kfree(user); | |
992 | return 0; | |
993 | } | |
994 | ||
995 | const struct file_operations kmsg_fops = { | |
996 | .open = devkmsg_open, | |
997 | .read = devkmsg_read, | |
998 | .write_iter = devkmsg_write, | |
999 | .llseek = devkmsg_llseek, | |
1000 | .poll = devkmsg_poll, | |
1001 | .release = devkmsg_release, | |
1002 | }; | |
1003 | ||
1004 | #ifdef CONFIG_CRASH_CORE | |
1005 | /* | |
1006 | * This appends the listed symbols to /proc/vmcore | |
1007 | * | |
1008 | * /proc/vmcore is used by various utilities, like crash and makedumpfile to | |
1009 | * obtain access to symbols that are otherwise very difficult to locate. These | |
1010 | * symbols are specifically used so that utilities can access and extract the | |
1011 | * dmesg log from a vmcore file after a crash. | |
1012 | */ | |
1013 | void log_buf_vmcoreinfo_setup(void) | |
1014 | { | |
1015 | VMCOREINFO_SYMBOL(log_buf); | |
1016 | VMCOREINFO_SYMBOL(log_buf_len); | |
1017 | VMCOREINFO_SYMBOL(log_first_idx); | |
1018 | VMCOREINFO_SYMBOL(clear_idx); | |
1019 | VMCOREINFO_SYMBOL(log_next_idx); | |
1020 | /* | |
1021 | * Export struct printk_log size and field offsets. User space tools can | |
1022 | * parse it and detect any changes to structure down the line. | |
1023 | */ | |
1024 | VMCOREINFO_STRUCT_SIZE(printk_log); | |
1025 | VMCOREINFO_OFFSET(printk_log, ts_nsec); | |
1026 | VMCOREINFO_OFFSET(printk_log, len); | |
1027 | VMCOREINFO_OFFSET(printk_log, text_len); | |
1028 | VMCOREINFO_OFFSET(printk_log, dict_len); | |
1029 | } | |
1030 | #endif | |
1031 | ||
1032 | /* requested log_buf_len from kernel cmdline */ | |
1033 | static unsigned long __initdata new_log_buf_len; | |
1034 | ||
1035 | /* we practice scaling the ring buffer by powers of 2 */ | |
1036 | static void __init log_buf_len_update(unsigned size) | |
1037 | { | |
1038 | if (size) | |
1039 | size = roundup_pow_of_two(size); | |
1040 | if (size > log_buf_len) | |
1041 | new_log_buf_len = size; | |
1042 | } | |
1043 | ||
1044 | /* save requested log_buf_len since it's too early to process it */ | |
1045 | static int __init log_buf_len_setup(char *str) | |
1046 | { | |
1047 | unsigned size = memparse(str, &str); | |
1048 | ||
1049 | log_buf_len_update(size); | |
1050 | ||
1051 | return 0; | |
1052 | } | |
1053 | early_param("log_buf_len", log_buf_len_setup); | |
1054 | ||
1055 | #ifdef CONFIG_SMP | |
1056 | #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) | |
1057 | ||
1058 | static void __init log_buf_add_cpu(void) | |
1059 | { | |
1060 | unsigned int cpu_extra; | |
1061 | ||
1062 | /* | |
1063 | * archs should set up cpu_possible_bits properly with | |
1064 | * set_cpu_possible() after setup_arch() but just in | |
1065 | * case lets ensure this is valid. | |
1066 | */ | |
1067 | if (num_possible_cpus() == 1) | |
1068 | return; | |
1069 | ||
1070 | cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; | |
1071 | ||
1072 | /* by default this will only continue through for large > 64 CPUs */ | |
1073 | if (cpu_extra <= __LOG_BUF_LEN / 2) | |
1074 | return; | |
1075 | ||
1076 | pr_info("log_buf_len individual max cpu contribution: %d bytes\n", | |
1077 | __LOG_CPU_MAX_BUF_LEN); | |
1078 | pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", | |
1079 | cpu_extra); | |
1080 | pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); | |
1081 | ||
1082 | log_buf_len_update(cpu_extra + __LOG_BUF_LEN); | |
1083 | } | |
1084 | #else /* !CONFIG_SMP */ | |
1085 | static inline void log_buf_add_cpu(void) {} | |
1086 | #endif /* CONFIG_SMP */ | |
1087 | ||
1088 | void __init setup_log_buf(int early) | |
1089 | { | |
1090 | unsigned long flags; | |
1091 | char *new_log_buf; | |
1092 | int free; | |
1093 | ||
1094 | if (log_buf != __log_buf) | |
1095 | return; | |
1096 | ||
1097 | if (!early && !new_log_buf_len) | |
1098 | log_buf_add_cpu(); | |
1099 | ||
1100 | if (!new_log_buf_len) | |
1101 | return; | |
1102 | ||
1103 | if (early) { | |
1104 | new_log_buf = | |
1105 | memblock_virt_alloc(new_log_buf_len, LOG_ALIGN); | |
1106 | } else { | |
1107 | new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len, | |
1108 | LOG_ALIGN); | |
1109 | } | |
1110 | ||
1111 | if (unlikely(!new_log_buf)) { | |
1112 | pr_err("log_buf_len: %ld bytes not available\n", | |
1113 | new_log_buf_len); | |
1114 | return; | |
1115 | } | |
1116 | ||
1117 | logbuf_lock_irqsave(flags); | |
1118 | log_buf_len = new_log_buf_len; | |
1119 | log_buf = new_log_buf; | |
1120 | new_log_buf_len = 0; | |
1121 | free = __LOG_BUF_LEN - log_next_idx; | |
1122 | memcpy(log_buf, __log_buf, __LOG_BUF_LEN); | |
1123 | logbuf_unlock_irqrestore(flags); | |
1124 | ||
1125 | pr_info("log_buf_len: %d bytes\n", log_buf_len); | |
1126 | pr_info("early log buf free: %d(%d%%)\n", | |
1127 | free, (free * 100) / __LOG_BUF_LEN); | |
1128 | } | |
1129 | ||
1130 | static bool __read_mostly ignore_loglevel; | |
1131 | ||
1132 | static int __init ignore_loglevel_setup(char *str) | |
1133 | { | |
1134 | ignore_loglevel = true; | |
1135 | pr_info("debug: ignoring loglevel setting.\n"); | |
1136 | ||
1137 | return 0; | |
1138 | } | |
1139 | ||
1140 | early_param("ignore_loglevel", ignore_loglevel_setup); | |
1141 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); | |
1142 | MODULE_PARM_DESC(ignore_loglevel, | |
1143 | "ignore loglevel setting (prints all kernel messages to the console)"); | |
1144 | ||
1145 | static bool suppress_message_printing(int level) | |
1146 | { | |
1147 | return (level >= console_loglevel && !ignore_loglevel); | |
1148 | } | |
1149 | ||
1150 | #ifdef CONFIG_BOOT_PRINTK_DELAY | |
1151 | ||
1152 | static int boot_delay; /* msecs delay after each printk during bootup */ | |
1153 | static unsigned long long loops_per_msec; /* based on boot_delay */ | |
1154 | ||
1155 | static int __init boot_delay_setup(char *str) | |
1156 | { | |
1157 | unsigned long lpj; | |
1158 | ||
1159 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
1160 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
1161 | ||
1162 | get_option(&str, &boot_delay); | |
1163 | if (boot_delay > 10 * 1000) | |
1164 | boot_delay = 0; | |
1165 | ||
1166 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " | |
1167 | "HZ: %d, loops_per_msec: %llu\n", | |
1168 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
1169 | return 0; | |
1170 | } | |
1171 | early_param("boot_delay", boot_delay_setup); | |
1172 | ||
1173 | static void boot_delay_msec(int level) | |
1174 | { | |
1175 | unsigned long long k; | |
1176 | unsigned long timeout; | |
1177 | ||
1178 | if ((boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
1179 | || suppress_message_printing(level)) { | |
1180 | return; | |
1181 | } | |
1182 | ||
1183 | k = (unsigned long long)loops_per_msec * boot_delay; | |
1184 | ||
1185 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
1186 | while (k) { | |
1187 | k--; | |
1188 | cpu_relax(); | |
1189 | /* | |
1190 | * use (volatile) jiffies to prevent | |
1191 | * compiler reduction; loop termination via jiffies | |
1192 | * is secondary and may or may not happen. | |
1193 | */ | |
1194 | if (time_after(jiffies, timeout)) | |
1195 | break; | |
1196 | touch_nmi_watchdog(); | |
1197 | } | |
1198 | } | |
1199 | #else | |
1200 | static inline void boot_delay_msec(int level) | |
1201 | { | |
1202 | } | |
1203 | #endif | |
1204 | ||
1205 | static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); | |
1206 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); | |
1207 | ||
1208 | static size_t print_time(u64 ts, char *buf) | |
1209 | { | |
1210 | unsigned long rem_nsec; | |
1211 | ||
1212 | if (!printk_time) | |
1213 | return 0; | |
1214 | ||
1215 | rem_nsec = do_div(ts, 1000000000); | |
1216 | ||
1217 | if (!buf) | |
1218 | return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts); | |
1219 | ||
1220 | return sprintf(buf, "[%5lu.%06lu] ", | |
1221 | (unsigned long)ts, rem_nsec / 1000); | |
1222 | } | |
1223 | ||
1224 | static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf) | |
1225 | { | |
1226 | size_t len = 0; | |
1227 | unsigned int prefix = (msg->facility << 3) | msg->level; | |
1228 | ||
1229 | if (syslog) { | |
1230 | if (buf) { | |
1231 | len += sprintf(buf, "<%u>", prefix); | |
1232 | } else { | |
1233 | len += 3; | |
1234 | if (prefix > 999) | |
1235 | len += 3; | |
1236 | else if (prefix > 99) | |
1237 | len += 2; | |
1238 | else if (prefix > 9) | |
1239 | len++; | |
1240 | } | |
1241 | } | |
1242 | ||
1243 | len += print_time(msg->ts_nsec, buf ? buf + len : NULL); | |
1244 | return len; | |
1245 | } | |
1246 | ||
1247 | static size_t msg_print_text(const struct printk_log *msg, bool syslog, char *buf, size_t size) | |
1248 | { | |
1249 | const char *text = log_text(msg); | |
1250 | size_t text_size = msg->text_len; | |
1251 | size_t len = 0; | |
1252 | ||
1253 | do { | |
1254 | const char *next = memchr(text, '\n', text_size); | |
1255 | size_t text_len; | |
1256 | ||
1257 | if (next) { | |
1258 | text_len = next - text; | |
1259 | next++; | |
1260 | text_size -= next - text; | |
1261 | } else { | |
1262 | text_len = text_size; | |
1263 | } | |
1264 | ||
1265 | if (buf) { | |
1266 | if (print_prefix(msg, syslog, NULL) + | |
1267 | text_len + 1 >= size - len) | |
1268 | break; | |
1269 | ||
1270 | len += print_prefix(msg, syslog, buf + len); | |
1271 | memcpy(buf + len, text, text_len); | |
1272 | len += text_len; | |
1273 | buf[len++] = '\n'; | |
1274 | } else { | |
1275 | /* SYSLOG_ACTION_* buffer size only calculation */ | |
1276 | len += print_prefix(msg, syslog, NULL); | |
1277 | len += text_len; | |
1278 | len++; | |
1279 | } | |
1280 | ||
1281 | text = next; | |
1282 | } while (text); | |
1283 | ||
1284 | return len; | |
1285 | } | |
1286 | ||
1287 | static int syslog_print(char __user *buf, int size) | |
1288 | { | |
1289 | char *text; | |
1290 | struct printk_log *msg; | |
1291 | int len = 0; | |
1292 | ||
1293 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); | |
1294 | if (!text) | |
1295 | return -ENOMEM; | |
1296 | ||
1297 | while (size > 0) { | |
1298 | size_t n; | |
1299 | size_t skip; | |
1300 | ||
1301 | logbuf_lock_irq(); | |
1302 | if (syslog_seq < log_first_seq) { | |
1303 | /* messages are gone, move to first one */ | |
1304 | syslog_seq = log_first_seq; | |
1305 | syslog_idx = log_first_idx; | |
1306 | syslog_partial = 0; | |
1307 | } | |
1308 | if (syslog_seq == log_next_seq) { | |
1309 | logbuf_unlock_irq(); | |
1310 | break; | |
1311 | } | |
1312 | ||
1313 | skip = syslog_partial; | |
1314 | msg = log_from_idx(syslog_idx); | |
1315 | n = msg_print_text(msg, true, text, LOG_LINE_MAX + PREFIX_MAX); | |
1316 | if (n - syslog_partial <= size) { | |
1317 | /* message fits into buffer, move forward */ | |
1318 | syslog_idx = log_next(syslog_idx); | |
1319 | syslog_seq++; | |
1320 | n -= syslog_partial; | |
1321 | syslog_partial = 0; | |
1322 | } else if (!len){ | |
1323 | /* partial read(), remember position */ | |
1324 | n = size; | |
1325 | syslog_partial += n; | |
1326 | } else | |
1327 | n = 0; | |
1328 | logbuf_unlock_irq(); | |
1329 | ||
1330 | if (!n) | |
1331 | break; | |
1332 | ||
1333 | if (copy_to_user(buf, text + skip, n)) { | |
1334 | if (!len) | |
1335 | len = -EFAULT; | |
1336 | break; | |
1337 | } | |
1338 | ||
1339 | len += n; | |
1340 | size -= n; | |
1341 | buf += n; | |
1342 | } | |
1343 | ||
1344 | kfree(text); | |
1345 | return len; | |
1346 | } | |
1347 | ||
1348 | static int syslog_print_all(char __user *buf, int size, bool clear) | |
1349 | { | |
1350 | char *text; | |
1351 | int len = 0; | |
1352 | ||
1353 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); | |
1354 | if (!text) | |
1355 | return -ENOMEM; | |
1356 | ||
1357 | logbuf_lock_irq(); | |
1358 | if (buf) { | |
1359 | u64 next_seq; | |
1360 | u64 seq; | |
1361 | u32 idx; | |
1362 | ||
1363 | /* | |
1364 | * Find first record that fits, including all following records, | |
1365 | * into the user-provided buffer for this dump. | |
1366 | */ | |
1367 | seq = clear_seq; | |
1368 | idx = clear_idx; | |
1369 | while (seq < log_next_seq) { | |
1370 | struct printk_log *msg = log_from_idx(idx); | |
1371 | ||
1372 | len += msg_print_text(msg, true, NULL, 0); | |
1373 | idx = log_next(idx); | |
1374 | seq++; | |
1375 | } | |
1376 | ||
1377 | /* move first record forward until length fits into the buffer */ | |
1378 | seq = clear_seq; | |
1379 | idx = clear_idx; | |
1380 | while (len > size && seq < log_next_seq) { | |
1381 | struct printk_log *msg = log_from_idx(idx); | |
1382 | ||
1383 | len -= msg_print_text(msg, true, NULL, 0); | |
1384 | idx = log_next(idx); | |
1385 | seq++; | |
1386 | } | |
1387 | ||
1388 | /* last message fitting into this dump */ | |
1389 | next_seq = log_next_seq; | |
1390 | ||
1391 | len = 0; | |
1392 | while (len >= 0 && seq < next_seq) { | |
1393 | struct printk_log *msg = log_from_idx(idx); | |
1394 | int textlen; | |
1395 | ||
1396 | textlen = msg_print_text(msg, true, text, | |
1397 | LOG_LINE_MAX + PREFIX_MAX); | |
1398 | if (textlen < 0) { | |
1399 | len = textlen; | |
1400 | break; | |
1401 | } | |
1402 | idx = log_next(idx); | |
1403 | seq++; | |
1404 | ||
1405 | logbuf_unlock_irq(); | |
1406 | if (copy_to_user(buf + len, text, textlen)) | |
1407 | len = -EFAULT; | |
1408 | else | |
1409 | len += textlen; | |
1410 | logbuf_lock_irq(); | |
1411 | ||
1412 | if (seq < log_first_seq) { | |
1413 | /* messages are gone, move to next one */ | |
1414 | seq = log_first_seq; | |
1415 | idx = log_first_idx; | |
1416 | } | |
1417 | } | |
1418 | } | |
1419 | ||
1420 | if (clear) { | |
1421 | clear_seq = log_next_seq; | |
1422 | clear_idx = log_next_idx; | |
1423 | } | |
1424 | logbuf_unlock_irq(); | |
1425 | ||
1426 | kfree(text); | |
1427 | return len; | |
1428 | } | |
1429 | ||
1430 | int do_syslog(int type, char __user *buf, int len, int source) | |
1431 | { | |
1432 | bool clear = false; | |
1433 | static int saved_console_loglevel = LOGLEVEL_DEFAULT; | |
1434 | int error; | |
1435 | ||
1436 | error = check_syslog_permissions(type, source); | |
1437 | if (error) | |
1438 | goto out; | |
1439 | ||
1440 | switch (type) { | |
1441 | case SYSLOG_ACTION_CLOSE: /* Close log */ | |
1442 | break; | |
1443 | case SYSLOG_ACTION_OPEN: /* Open log */ | |
1444 | break; | |
1445 | case SYSLOG_ACTION_READ: /* Read from log */ | |
1446 | error = -EINVAL; | |
1447 | if (!buf || len < 0) | |
1448 | goto out; | |
1449 | error = 0; | |
1450 | if (!len) | |
1451 | goto out; | |
1452 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
1453 | error = -EFAULT; | |
1454 | goto out; | |
1455 | } | |
1456 | error = wait_event_interruptible(log_wait, | |
1457 | syslog_seq != log_next_seq); | |
1458 | if (error) | |
1459 | goto out; | |
1460 | error = syslog_print(buf, len); | |
1461 | break; | |
1462 | /* Read/clear last kernel messages */ | |
1463 | case SYSLOG_ACTION_READ_CLEAR: | |
1464 | clear = true; | |
1465 | /* FALL THRU */ | |
1466 | /* Read last kernel messages */ | |
1467 | case SYSLOG_ACTION_READ_ALL: | |
1468 | error = -EINVAL; | |
1469 | if (!buf || len < 0) | |
1470 | goto out; | |
1471 | error = 0; | |
1472 | if (!len) | |
1473 | goto out; | |
1474 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
1475 | error = -EFAULT; | |
1476 | goto out; | |
1477 | } | |
1478 | error = syslog_print_all(buf, len, clear); | |
1479 | break; | |
1480 | /* Clear ring buffer */ | |
1481 | case SYSLOG_ACTION_CLEAR: | |
1482 | syslog_print_all(NULL, 0, true); | |
1483 | break; | |
1484 | /* Disable logging to console */ | |
1485 | case SYSLOG_ACTION_CONSOLE_OFF: | |
1486 | if (saved_console_loglevel == LOGLEVEL_DEFAULT) | |
1487 | saved_console_loglevel = console_loglevel; | |
1488 | console_loglevel = minimum_console_loglevel; | |
1489 | break; | |
1490 | /* Enable logging to console */ | |
1491 | case SYSLOG_ACTION_CONSOLE_ON: | |
1492 | if (saved_console_loglevel != LOGLEVEL_DEFAULT) { | |
1493 | console_loglevel = saved_console_loglevel; | |
1494 | saved_console_loglevel = LOGLEVEL_DEFAULT; | |
1495 | } | |
1496 | break; | |
1497 | /* Set level of messages printed to console */ | |
1498 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1499 | error = -EINVAL; | |
1500 | if (len < 1 || len > 8) | |
1501 | goto out; | |
1502 | if (len < minimum_console_loglevel) | |
1503 | len = minimum_console_loglevel; | |
1504 | console_loglevel = len; | |
1505 | /* Implicitly re-enable logging to console */ | |
1506 | saved_console_loglevel = LOGLEVEL_DEFAULT; | |
1507 | error = 0; | |
1508 | break; | |
1509 | /* Number of chars in the log buffer */ | |
1510 | case SYSLOG_ACTION_SIZE_UNREAD: | |
1511 | logbuf_lock_irq(); | |
1512 | if (syslog_seq < log_first_seq) { | |
1513 | /* messages are gone, move to first one */ | |
1514 | syslog_seq = log_first_seq; | |
1515 | syslog_idx = log_first_idx; | |
1516 | syslog_partial = 0; | |
1517 | } | |
1518 | if (source == SYSLOG_FROM_PROC) { | |
1519 | /* | |
1520 | * Short-cut for poll(/"proc/kmsg") which simply checks | |
1521 | * for pending data, not the size; return the count of | |
1522 | * records, not the length. | |
1523 | */ | |
1524 | error = log_next_seq - syslog_seq; | |
1525 | } else { | |
1526 | u64 seq = syslog_seq; | |
1527 | u32 idx = syslog_idx; | |
1528 | ||
1529 | error = 0; | |
1530 | while (seq < log_next_seq) { | |
1531 | struct printk_log *msg = log_from_idx(idx); | |
1532 | ||
1533 | error += msg_print_text(msg, true, NULL, 0); | |
1534 | idx = log_next(idx); | |
1535 | seq++; | |
1536 | } | |
1537 | error -= syslog_partial; | |
1538 | } | |
1539 | logbuf_unlock_irq(); | |
1540 | break; | |
1541 | /* Size of the log buffer */ | |
1542 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1543 | error = log_buf_len; | |
1544 | break; | |
1545 | default: | |
1546 | error = -EINVAL; | |
1547 | break; | |
1548 | } | |
1549 | out: | |
1550 | return error; | |
1551 | } | |
1552 | ||
1553 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) | |
1554 | { | |
1555 | return do_syslog(type, buf, len, SYSLOG_FROM_READER); | |
1556 | } | |
1557 | ||
1558 | /* | |
1559 | * Call the console drivers, asking them to write out | |
1560 | * log_buf[start] to log_buf[end - 1]. | |
1561 | * The console_lock must be held. | |
1562 | */ | |
1563 | static void call_console_drivers(const char *ext_text, size_t ext_len, | |
1564 | const char *text, size_t len) | |
1565 | { | |
1566 | struct console *con; | |
1567 | ||
1568 | trace_console_rcuidle(text, len); | |
1569 | ||
1570 | if (!console_drivers) | |
1571 | return; | |
1572 | ||
1573 | for_each_console(con) { | |
1574 | if (exclusive_console && con != exclusive_console) | |
1575 | continue; | |
1576 | if (!(con->flags & CON_ENABLED)) | |
1577 | continue; | |
1578 | if (!con->write) | |
1579 | continue; | |
1580 | if (!cpu_online(smp_processor_id()) && | |
1581 | !(con->flags & CON_ANYTIME)) | |
1582 | continue; | |
1583 | if (con->flags & CON_EXTENDED) | |
1584 | con->write(con, ext_text, ext_len); | |
1585 | else | |
1586 | con->write(con, text, len); | |
1587 | } | |
1588 | } | |
1589 | ||
1590 | int printk_delay_msec __read_mostly; | |
1591 | ||
1592 | static inline void printk_delay(void) | |
1593 | { | |
1594 | if (unlikely(printk_delay_msec)) { | |
1595 | int m = printk_delay_msec; | |
1596 | ||
1597 | while (m--) { | |
1598 | mdelay(1); | |
1599 | touch_nmi_watchdog(); | |
1600 | } | |
1601 | } | |
1602 | } | |
1603 | ||
1604 | /* | |
1605 | * Continuation lines are buffered, and not committed to the record buffer | |
1606 | * until the line is complete, or a race forces it. The line fragments | |
1607 | * though, are printed immediately to the consoles to ensure everything has | |
1608 | * reached the console in case of a kernel crash. | |
1609 | */ | |
1610 | static struct cont { | |
1611 | char buf[LOG_LINE_MAX]; | |
1612 | size_t len; /* length == 0 means unused buffer */ | |
1613 | struct task_struct *owner; /* task of first print*/ | |
1614 | u64 ts_nsec; /* time of first print */ | |
1615 | u8 level; /* log level of first message */ | |
1616 | u8 facility; /* log facility of first message */ | |
1617 | enum log_flags flags; /* prefix, newline flags */ | |
1618 | } cont; | |
1619 | ||
1620 | static void cont_flush(void) | |
1621 | { | |
1622 | if (cont.len == 0) | |
1623 | return; | |
1624 | ||
1625 | log_store(cont.facility, cont.level, cont.flags, cont.ts_nsec, | |
1626 | NULL, 0, cont.buf, cont.len); | |
1627 | cont.len = 0; | |
1628 | } | |
1629 | ||
1630 | static bool cont_add(int facility, int level, enum log_flags flags, const char *text, size_t len) | |
1631 | { | |
1632 | /* | |
1633 | * If ext consoles are present, flush and skip in-kernel | |
1634 | * continuation. See nr_ext_console_drivers definition. Also, if | |
1635 | * the line gets too long, split it up in separate records. | |
1636 | */ | |
1637 | if (nr_ext_console_drivers || cont.len + len > sizeof(cont.buf)) { | |
1638 | cont_flush(); | |
1639 | return false; | |
1640 | } | |
1641 | ||
1642 | if (!cont.len) { | |
1643 | cont.facility = facility; | |
1644 | cont.level = level; | |
1645 | cont.owner = current; | |
1646 | cont.ts_nsec = local_clock(); | |
1647 | cont.flags = flags; | |
1648 | } | |
1649 | ||
1650 | memcpy(cont.buf + cont.len, text, len); | |
1651 | cont.len += len; | |
1652 | ||
1653 | // The original flags come from the first line, | |
1654 | // but later continuations can add a newline. | |
1655 | if (flags & LOG_NEWLINE) { | |
1656 | cont.flags |= LOG_NEWLINE; | |
1657 | cont_flush(); | |
1658 | } | |
1659 | ||
1660 | if (cont.len > (sizeof(cont.buf) * 80) / 100) | |
1661 | cont_flush(); | |
1662 | ||
1663 | return true; | |
1664 | } | |
1665 | ||
1666 | static size_t log_output(int facility, int level, enum log_flags lflags, const char *dict, size_t dictlen, char *text, size_t text_len) | |
1667 | { | |
1668 | /* | |
1669 | * If an earlier line was buffered, and we're a continuation | |
1670 | * write from the same process, try to add it to the buffer. | |
1671 | */ | |
1672 | if (cont.len) { | |
1673 | if (cont.owner == current && (lflags & LOG_CONT)) { | |
1674 | if (cont_add(facility, level, lflags, text, text_len)) | |
1675 | return text_len; | |
1676 | } | |
1677 | /* Otherwise, make sure it's flushed */ | |
1678 | cont_flush(); | |
1679 | } | |
1680 | ||
1681 | /* Skip empty continuation lines that couldn't be added - they just flush */ | |
1682 | if (!text_len && (lflags & LOG_CONT)) | |
1683 | return 0; | |
1684 | ||
1685 | /* If it doesn't end in a newline, try to buffer the current line */ | |
1686 | if (!(lflags & LOG_NEWLINE)) { | |
1687 | if (cont_add(facility, level, lflags, text, text_len)) | |
1688 | return text_len; | |
1689 | } | |
1690 | ||
1691 | /* Store it in the record log */ | |
1692 | return log_store(facility, level, lflags, 0, dict, dictlen, text, text_len); | |
1693 | } | |
1694 | ||
1695 | asmlinkage int vprintk_emit(int facility, int level, | |
1696 | const char *dict, size_t dictlen, | |
1697 | const char *fmt, va_list args) | |
1698 | { | |
1699 | static char textbuf[LOG_LINE_MAX]; | |
1700 | char *text = textbuf; | |
1701 | size_t text_len = 0; | |
1702 | enum log_flags lflags = 0; | |
1703 | unsigned long flags; | |
1704 | int printed_len = 0; | |
1705 | bool in_sched = false; | |
1706 | ||
1707 | if (level == LOGLEVEL_SCHED) { | |
1708 | level = LOGLEVEL_DEFAULT; | |
1709 | in_sched = true; | |
1710 | } | |
1711 | ||
1712 | boot_delay_msec(level); | |
1713 | printk_delay(); | |
1714 | ||
1715 | /* This stops the holder of console_sem just where we want him */ | |
1716 | logbuf_lock_irqsave(flags); | |
1717 | /* | |
1718 | * The printf needs to come first; we need the syslog | |
1719 | * prefix which might be passed-in as a parameter. | |
1720 | */ | |
1721 | text_len = vscnprintf(text, sizeof(textbuf), fmt, args); | |
1722 | ||
1723 | /* mark and strip a trailing newline */ | |
1724 | if (text_len && text[text_len-1] == '\n') { | |
1725 | text_len--; | |
1726 | lflags |= LOG_NEWLINE; | |
1727 | } | |
1728 | ||
1729 | /* strip kernel syslog prefix and extract log level or control flags */ | |
1730 | if (facility == 0) { | |
1731 | int kern_level; | |
1732 | ||
1733 | while ((kern_level = printk_get_level(text)) != 0) { | |
1734 | switch (kern_level) { | |
1735 | case '0' ... '7': | |
1736 | if (level == LOGLEVEL_DEFAULT) | |
1737 | level = kern_level - '0'; | |
1738 | /* fallthrough */ | |
1739 | case 'd': /* KERN_DEFAULT */ | |
1740 | lflags |= LOG_PREFIX; | |
1741 | break; | |
1742 | case 'c': /* KERN_CONT */ | |
1743 | lflags |= LOG_CONT; | |
1744 | } | |
1745 | ||
1746 | text_len -= 2; | |
1747 | text += 2; | |
1748 | } | |
1749 | } | |
1750 | ||
1751 | if (level == LOGLEVEL_DEFAULT) | |
1752 | level = default_message_loglevel; | |
1753 | ||
1754 | if (dict) | |
1755 | lflags |= LOG_PREFIX|LOG_NEWLINE; | |
1756 | ||
1757 | printed_len += log_output(facility, level, lflags, dict, dictlen, text, text_len); | |
1758 | ||
1759 | logbuf_unlock_irqrestore(flags); | |
1760 | ||
1761 | /* If called from the scheduler, we can not call up(). */ | |
1762 | if (!in_sched) { | |
1763 | /* | |
1764 | * Try to acquire and then immediately release the console | |
1765 | * semaphore. The release will print out buffers and wake up | |
1766 | * /dev/kmsg and syslog() users. | |
1767 | */ | |
1768 | if (console_trylock()) | |
1769 | console_unlock(); | |
1770 | } | |
1771 | ||
1772 | return printed_len; | |
1773 | } | |
1774 | EXPORT_SYMBOL(vprintk_emit); | |
1775 | ||
1776 | asmlinkage int vprintk(const char *fmt, va_list args) | |
1777 | { | |
1778 | return vprintk_func(fmt, args); | |
1779 | } | |
1780 | EXPORT_SYMBOL(vprintk); | |
1781 | ||
1782 | asmlinkage int printk_emit(int facility, int level, | |
1783 | const char *dict, size_t dictlen, | |
1784 | const char *fmt, ...) | |
1785 | { | |
1786 | va_list args; | |
1787 | int r; | |
1788 | ||
1789 | va_start(args, fmt); | |
1790 | r = vprintk_emit(facility, level, dict, dictlen, fmt, args); | |
1791 | va_end(args); | |
1792 | ||
1793 | return r; | |
1794 | } | |
1795 | EXPORT_SYMBOL(printk_emit); | |
1796 | ||
1797 | int vprintk_default(const char *fmt, va_list args) | |
1798 | { | |
1799 | int r; | |
1800 | ||
1801 | #ifdef CONFIG_KGDB_KDB | |
1802 | /* Allow to pass printk() to kdb but avoid a recursion. */ | |
1803 | if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) { | |
1804 | r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args); | |
1805 | return r; | |
1806 | } | |
1807 | #endif | |
1808 | r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); | |
1809 | ||
1810 | return r; | |
1811 | } | |
1812 | EXPORT_SYMBOL_GPL(vprintk_default); | |
1813 | ||
1814 | /** | |
1815 | * printk - print a kernel message | |
1816 | * @fmt: format string | |
1817 | * | |
1818 | * This is printk(). It can be called from any context. We want it to work. | |
1819 | * | |
1820 | * We try to grab the console_lock. If we succeed, it's easy - we log the | |
1821 | * output and call the console drivers. If we fail to get the semaphore, we | |
1822 | * place the output into the log buffer and return. The current holder of | |
1823 | * the console_sem will notice the new output in console_unlock(); and will | |
1824 | * send it to the consoles before releasing the lock. | |
1825 | * | |
1826 | * One effect of this deferred printing is that code which calls printk() and | |
1827 | * then changes console_loglevel may break. This is because console_loglevel | |
1828 | * is inspected when the actual printing occurs. | |
1829 | * | |
1830 | * See also: | |
1831 | * printf(3) | |
1832 | * | |
1833 | * See the vsnprintf() documentation for format string extensions over C99. | |
1834 | */ | |
1835 | asmlinkage __visible int printk(const char *fmt, ...) | |
1836 | { | |
1837 | va_list args; | |
1838 | int r; | |
1839 | ||
1840 | va_start(args, fmt); | |
1841 | r = vprintk_func(fmt, args); | |
1842 | va_end(args); | |
1843 | ||
1844 | return r; | |
1845 | } | |
1846 | EXPORT_SYMBOL(printk); | |
1847 | ||
1848 | #else /* CONFIG_PRINTK */ | |
1849 | ||
1850 | #define LOG_LINE_MAX 0 | |
1851 | #define PREFIX_MAX 0 | |
1852 | ||
1853 | static u64 syslog_seq; | |
1854 | static u32 syslog_idx; | |
1855 | static u64 console_seq; | |
1856 | static u32 console_idx; | |
1857 | static u64 log_first_seq; | |
1858 | static u32 log_first_idx; | |
1859 | static u64 log_next_seq; | |
1860 | static char *log_text(const struct printk_log *msg) { return NULL; } | |
1861 | static char *log_dict(const struct printk_log *msg) { return NULL; } | |
1862 | static struct printk_log *log_from_idx(u32 idx) { return NULL; } | |
1863 | static u32 log_next(u32 idx) { return 0; } | |
1864 | static ssize_t msg_print_ext_header(char *buf, size_t size, | |
1865 | struct printk_log *msg, | |
1866 | u64 seq) { return 0; } | |
1867 | static ssize_t msg_print_ext_body(char *buf, size_t size, | |
1868 | char *dict, size_t dict_len, | |
1869 | char *text, size_t text_len) { return 0; } | |
1870 | static void call_console_drivers(const char *ext_text, size_t ext_len, | |
1871 | const char *text, size_t len) {} | |
1872 | static size_t msg_print_text(const struct printk_log *msg, | |
1873 | bool syslog, char *buf, size_t size) { return 0; } | |
1874 | static bool suppress_message_printing(int level) { return false; } | |
1875 | ||
1876 | #endif /* CONFIG_PRINTK */ | |
1877 | ||
1878 | #ifdef CONFIG_EARLY_PRINTK | |
1879 | struct console *early_console; | |
1880 | ||
1881 | asmlinkage __visible void early_printk(const char *fmt, ...) | |
1882 | { | |
1883 | va_list ap; | |
1884 | char buf[512]; | |
1885 | int n; | |
1886 | ||
1887 | if (!early_console) | |
1888 | return; | |
1889 | ||
1890 | va_start(ap, fmt); | |
1891 | n = vscnprintf(buf, sizeof(buf), fmt, ap); | |
1892 | va_end(ap); | |
1893 | ||
1894 | early_console->write(early_console, buf, n); | |
1895 | } | |
1896 | #endif | |
1897 | ||
1898 | static int __add_preferred_console(char *name, int idx, char *options, | |
1899 | char *brl_options) | |
1900 | { | |
1901 | struct console_cmdline *c; | |
1902 | int i; | |
1903 | ||
1904 | /* | |
1905 | * See if this tty is not yet registered, and | |
1906 | * if we have a slot free. | |
1907 | */ | |
1908 | for (i = 0, c = console_cmdline; | |
1909 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
1910 | i++, c++) { | |
1911 | if (strcmp(c->name, name) == 0 && c->index == idx) { | |
1912 | if (!brl_options) | |
1913 | preferred_console = i; | |
1914 | return 0; | |
1915 | } | |
1916 | } | |
1917 | if (i == MAX_CMDLINECONSOLES) | |
1918 | return -E2BIG; | |
1919 | if (!brl_options) | |
1920 | preferred_console = i; | |
1921 | strlcpy(c->name, name, sizeof(c->name)); | |
1922 | c->options = options; | |
1923 | braille_set_options(c, brl_options); | |
1924 | ||
1925 | c->index = idx; | |
1926 | return 0; | |
1927 | } | |
1928 | /* | |
1929 | * Set up a console. Called via do_early_param() in init/main.c | |
1930 | * for each "console=" parameter in the boot command line. | |
1931 | */ | |
1932 | static int __init console_setup(char *str) | |
1933 | { | |
1934 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ | |
1935 | char *s, *options, *brl_options = NULL; | |
1936 | int idx; | |
1937 | ||
1938 | if (_braille_console_setup(&str, &brl_options)) | |
1939 | return 1; | |
1940 | ||
1941 | /* | |
1942 | * Decode str into name, index, options. | |
1943 | */ | |
1944 | if (str[0] >= '0' && str[0] <= '9') { | |
1945 | strcpy(buf, "ttyS"); | |
1946 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
1947 | } else { | |
1948 | strncpy(buf, str, sizeof(buf) - 1); | |
1949 | } | |
1950 | buf[sizeof(buf) - 1] = 0; | |
1951 | options = strchr(str, ','); | |
1952 | if (options) | |
1953 | *(options++) = 0; | |
1954 | #ifdef __sparc__ | |
1955 | if (!strcmp(str, "ttya")) | |
1956 | strcpy(buf, "ttyS0"); | |
1957 | if (!strcmp(str, "ttyb")) | |
1958 | strcpy(buf, "ttyS1"); | |
1959 | #endif | |
1960 | for (s = buf; *s; s++) | |
1961 | if (isdigit(*s) || *s == ',') | |
1962 | break; | |
1963 | idx = simple_strtoul(s, NULL, 10); | |
1964 | *s = 0; | |
1965 | ||
1966 | __add_preferred_console(buf, idx, options, brl_options); | |
1967 | console_set_on_cmdline = 1; | |
1968 | return 1; | |
1969 | } | |
1970 | __setup("console=", console_setup); | |
1971 | ||
1972 | /** | |
1973 | * add_preferred_console - add a device to the list of preferred consoles. | |
1974 | * @name: device name | |
1975 | * @idx: device index | |
1976 | * @options: options for this console | |
1977 | * | |
1978 | * The last preferred console added will be used for kernel messages | |
1979 | * and stdin/out/err for init. Normally this is used by console_setup | |
1980 | * above to handle user-supplied console arguments; however it can also | |
1981 | * be used by arch-specific code either to override the user or more | |
1982 | * commonly to provide a default console (ie from PROM variables) when | |
1983 | * the user has not supplied one. | |
1984 | */ | |
1985 | int add_preferred_console(char *name, int idx, char *options) | |
1986 | { | |
1987 | return __add_preferred_console(name, idx, options, NULL); | |
1988 | } | |
1989 | ||
1990 | bool console_suspend_enabled = true; | |
1991 | EXPORT_SYMBOL(console_suspend_enabled); | |
1992 | ||
1993 | static int __init console_suspend_disable(char *str) | |
1994 | { | |
1995 | console_suspend_enabled = false; | |
1996 | return 1; | |
1997 | } | |
1998 | __setup("no_console_suspend", console_suspend_disable); | |
1999 | module_param_named(console_suspend, console_suspend_enabled, | |
2000 | bool, S_IRUGO | S_IWUSR); | |
2001 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" | |
2002 | " and hibernate operations"); | |
2003 | ||
2004 | /** | |
2005 | * suspend_console - suspend the console subsystem | |
2006 | * | |
2007 | * This disables printk() while we go into suspend states | |
2008 | */ | |
2009 | void suspend_console(void) | |
2010 | { | |
2011 | if (!console_suspend_enabled) | |
2012 | return; | |
2013 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); | |
2014 | console_lock(); | |
2015 | console_suspended = 1; | |
2016 | up_console_sem(); | |
2017 | } | |
2018 | ||
2019 | void resume_console(void) | |
2020 | { | |
2021 | if (!console_suspend_enabled) | |
2022 | return; | |
2023 | down_console_sem(); | |
2024 | console_suspended = 0; | |
2025 | console_unlock(); | |
2026 | } | |
2027 | ||
2028 | /** | |
2029 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
2030 | * @cpu: unused | |
2031 | * | |
2032 | * If printk() is called from a CPU that is not online yet, the messages | |
2033 | * will be printed on the console only if there are CON_ANYTIME consoles. | |
2034 | * This function is called when a new CPU comes online (or fails to come | |
2035 | * up) or goes offline. | |
2036 | */ | |
2037 | static int console_cpu_notify(unsigned int cpu) | |
2038 | { | |
2039 | if (!cpuhp_tasks_frozen) { | |
2040 | /* If trylock fails, someone else is doing the printing */ | |
2041 | if (console_trylock()) | |
2042 | console_unlock(); | |
2043 | } | |
2044 | return 0; | |
2045 | } | |
2046 | ||
2047 | /** | |
2048 | * console_lock - lock the console system for exclusive use. | |
2049 | * | |
2050 | * Acquires a lock which guarantees that the caller has | |
2051 | * exclusive access to the console system and the console_drivers list. | |
2052 | * | |
2053 | * Can sleep, returns nothing. | |
2054 | */ | |
2055 | void console_lock(void) | |
2056 | { | |
2057 | might_sleep(); | |
2058 | ||
2059 | down_console_sem(); | |
2060 | if (console_suspended) | |
2061 | return; | |
2062 | console_locked = 1; | |
2063 | console_may_schedule = 1; | |
2064 | } | |
2065 | EXPORT_SYMBOL(console_lock); | |
2066 | ||
2067 | /** | |
2068 | * console_trylock - try to lock the console system for exclusive use. | |
2069 | * | |
2070 | * Try to acquire a lock which guarantees that the caller has exclusive | |
2071 | * access to the console system and the console_drivers list. | |
2072 | * | |
2073 | * returns 1 on success, and 0 on failure to acquire the lock. | |
2074 | */ | |
2075 | int console_trylock(void) | |
2076 | { | |
2077 | if (down_trylock_console_sem()) | |
2078 | return 0; | |
2079 | if (console_suspended) { | |
2080 | up_console_sem(); | |
2081 | return 0; | |
2082 | } | |
2083 | console_locked = 1; | |
2084 | /* | |
2085 | * When PREEMPT_COUNT disabled we can't reliably detect if it's | |
2086 | * safe to schedule (e.g. calling printk while holding a spin_lock), | |
2087 | * because preempt_disable()/preempt_enable() are just barriers there | |
2088 | * and preempt_count() is always 0. | |
2089 | * | |
2090 | * RCU read sections have a separate preemption counter when | |
2091 | * PREEMPT_RCU enabled thus we must take extra care and check | |
2092 | * rcu_preempt_depth(), otherwise RCU read sections modify | |
2093 | * preempt_count(). | |
2094 | */ | |
2095 | console_may_schedule = !oops_in_progress && | |
2096 | preemptible() && | |
2097 | !rcu_preempt_depth(); | |
2098 | return 1; | |
2099 | } | |
2100 | EXPORT_SYMBOL(console_trylock); | |
2101 | ||
2102 | int is_console_locked(void) | |
2103 | { | |
2104 | return console_locked; | |
2105 | } | |
2106 | ||
2107 | /* | |
2108 | * Check if we have any console that is capable of printing while cpu is | |
2109 | * booting or shutting down. Requires console_sem. | |
2110 | */ | |
2111 | static int have_callable_console(void) | |
2112 | { | |
2113 | struct console *con; | |
2114 | ||
2115 | for_each_console(con) | |
2116 | if ((con->flags & CON_ENABLED) && | |
2117 | (con->flags & CON_ANYTIME)) | |
2118 | return 1; | |
2119 | ||
2120 | return 0; | |
2121 | } | |
2122 | ||
2123 | /* | |
2124 | * Can we actually use the console at this time on this cpu? | |
2125 | * | |
2126 | * Console drivers may assume that per-cpu resources have been allocated. So | |
2127 | * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't | |
2128 | * call them until this CPU is officially up. | |
2129 | */ | |
2130 | static inline int can_use_console(void) | |
2131 | { | |
2132 | return cpu_online(raw_smp_processor_id()) || have_callable_console(); | |
2133 | } | |
2134 | ||
2135 | /** | |
2136 | * console_unlock - unlock the console system | |
2137 | * | |
2138 | * Releases the console_lock which the caller holds on the console system | |
2139 | * and the console driver list. | |
2140 | * | |
2141 | * While the console_lock was held, console output may have been buffered | |
2142 | * by printk(). If this is the case, console_unlock(); emits | |
2143 | * the output prior to releasing the lock. | |
2144 | * | |
2145 | * If there is output waiting, we wake /dev/kmsg and syslog() users. | |
2146 | * | |
2147 | * console_unlock(); may be called from any context. | |
2148 | */ | |
2149 | void console_unlock(void) | |
2150 | { | |
2151 | static char ext_text[CONSOLE_EXT_LOG_MAX]; | |
2152 | static char text[LOG_LINE_MAX + PREFIX_MAX]; | |
2153 | static u64 seen_seq; | |
2154 | unsigned long flags; | |
2155 | bool wake_klogd = false; | |
2156 | bool do_cond_resched, retry; | |
2157 | ||
2158 | if (console_suspended) { | |
2159 | up_console_sem(); | |
2160 | return; | |
2161 | } | |
2162 | ||
2163 | /* | |
2164 | * Console drivers are called with interrupts disabled, so | |
2165 | * @console_may_schedule should be cleared before; however, we may | |
2166 | * end up dumping a lot of lines, for example, if called from | |
2167 | * console registration path, and should invoke cond_resched() | |
2168 | * between lines if allowable. Not doing so can cause a very long | |
2169 | * scheduling stall on a slow console leading to RCU stall and | |
2170 | * softlockup warnings which exacerbate the issue with more | |
2171 | * messages practically incapacitating the system. | |
2172 | * | |
2173 | * console_trylock() is not able to detect the preemptive | |
2174 | * context reliably. Therefore the value must be stored before | |
2175 | * and cleared after the the "again" goto label. | |
2176 | */ | |
2177 | do_cond_resched = console_may_schedule; | |
2178 | again: | |
2179 | console_may_schedule = 0; | |
2180 | ||
2181 | /* | |
2182 | * We released the console_sem lock, so we need to recheck if | |
2183 | * cpu is online and (if not) is there at least one CON_ANYTIME | |
2184 | * console. | |
2185 | */ | |
2186 | if (!can_use_console()) { | |
2187 | console_locked = 0; | |
2188 | up_console_sem(); | |
2189 | return; | |
2190 | } | |
2191 | ||
2192 | for (;;) { | |
2193 | struct printk_log *msg; | |
2194 | size_t ext_len = 0; | |
2195 | size_t len; | |
2196 | ||
2197 | printk_safe_enter_irqsave(flags); | |
2198 | raw_spin_lock(&logbuf_lock); | |
2199 | if (seen_seq != log_next_seq) { | |
2200 | wake_klogd = true; | |
2201 | seen_seq = log_next_seq; | |
2202 | } | |
2203 | ||
2204 | if (console_seq < log_first_seq) { | |
2205 | len = sprintf(text, "** %u printk messages dropped ** ", | |
2206 | (unsigned)(log_first_seq - console_seq)); | |
2207 | ||
2208 | /* messages are gone, move to first one */ | |
2209 | console_seq = log_first_seq; | |
2210 | console_idx = log_first_idx; | |
2211 | } else { | |
2212 | len = 0; | |
2213 | } | |
2214 | skip: | |
2215 | if (console_seq == log_next_seq) | |
2216 | break; | |
2217 | ||
2218 | msg = log_from_idx(console_idx); | |
2219 | if (suppress_message_printing(msg->level)) { | |
2220 | /* | |
2221 | * Skip record we have buffered and already printed | |
2222 | * directly to the console when we received it, and | |
2223 | * record that has level above the console loglevel. | |
2224 | */ | |
2225 | console_idx = log_next(console_idx); | |
2226 | console_seq++; | |
2227 | goto skip; | |
2228 | } | |
2229 | ||
2230 | len += msg_print_text(msg, false, text + len, sizeof(text) - len); | |
2231 | if (nr_ext_console_drivers) { | |
2232 | ext_len = msg_print_ext_header(ext_text, | |
2233 | sizeof(ext_text), | |
2234 | msg, console_seq); | |
2235 | ext_len += msg_print_ext_body(ext_text + ext_len, | |
2236 | sizeof(ext_text) - ext_len, | |
2237 | log_dict(msg), msg->dict_len, | |
2238 | log_text(msg), msg->text_len); | |
2239 | } | |
2240 | console_idx = log_next(console_idx); | |
2241 | console_seq++; | |
2242 | raw_spin_unlock(&logbuf_lock); | |
2243 | ||
2244 | stop_critical_timings(); /* don't trace print latency */ | |
2245 | call_console_drivers(ext_text, ext_len, text, len); | |
2246 | start_critical_timings(); | |
2247 | printk_safe_exit_irqrestore(flags); | |
2248 | ||
2249 | if (do_cond_resched) | |
2250 | cond_resched(); | |
2251 | } | |
2252 | console_locked = 0; | |
2253 | ||
2254 | /* Release the exclusive_console once it is used */ | |
2255 | if (unlikely(exclusive_console)) | |
2256 | exclusive_console = NULL; | |
2257 | ||
2258 | raw_spin_unlock(&logbuf_lock); | |
2259 | ||
2260 | up_console_sem(); | |
2261 | ||
2262 | /* | |
2263 | * Someone could have filled up the buffer again, so re-check if there's | |
2264 | * something to flush. In case we cannot trylock the console_sem again, | |
2265 | * there's a new owner and the console_unlock() from them will do the | |
2266 | * flush, no worries. | |
2267 | */ | |
2268 | raw_spin_lock(&logbuf_lock); | |
2269 | retry = console_seq != log_next_seq; | |
2270 | raw_spin_unlock(&logbuf_lock); | |
2271 | printk_safe_exit_irqrestore(flags); | |
2272 | ||
2273 | if (retry && console_trylock()) | |
2274 | goto again; | |
2275 | ||
2276 | if (wake_klogd) | |
2277 | wake_up_klogd(); | |
2278 | } | |
2279 | EXPORT_SYMBOL(console_unlock); | |
2280 | ||
2281 | /** | |
2282 | * console_conditional_schedule - yield the CPU if required | |
2283 | * | |
2284 | * If the console code is currently allowed to sleep, and | |
2285 | * if this CPU should yield the CPU to another task, do | |
2286 | * so here. | |
2287 | * | |
2288 | * Must be called within console_lock();. | |
2289 | */ | |
2290 | void __sched console_conditional_schedule(void) | |
2291 | { | |
2292 | if (console_may_schedule) | |
2293 | cond_resched(); | |
2294 | } | |
2295 | EXPORT_SYMBOL(console_conditional_schedule); | |
2296 | ||
2297 | void console_unblank(void) | |
2298 | { | |
2299 | struct console *c; | |
2300 | ||
2301 | /* | |
2302 | * console_unblank can no longer be called in interrupt context unless | |
2303 | * oops_in_progress is set to 1.. | |
2304 | */ | |
2305 | if (oops_in_progress) { | |
2306 | if (down_trylock_console_sem() != 0) | |
2307 | return; | |
2308 | } else | |
2309 | console_lock(); | |
2310 | ||
2311 | console_locked = 1; | |
2312 | console_may_schedule = 0; | |
2313 | for_each_console(c) | |
2314 | if ((c->flags & CON_ENABLED) && c->unblank) | |
2315 | c->unblank(); | |
2316 | console_unlock(); | |
2317 | } | |
2318 | ||
2319 | /** | |
2320 | * console_flush_on_panic - flush console content on panic | |
2321 | * | |
2322 | * Immediately output all pending messages no matter what. | |
2323 | */ | |
2324 | void console_flush_on_panic(void) | |
2325 | { | |
2326 | /* | |
2327 | * If someone else is holding the console lock, trylock will fail | |
2328 | * and may_schedule may be set. Ignore and proceed to unlock so | |
2329 | * that messages are flushed out. As this can be called from any | |
2330 | * context and we don't want to get preempted while flushing, | |
2331 | * ensure may_schedule is cleared. | |
2332 | */ | |
2333 | console_trylock(); | |
2334 | console_may_schedule = 0; | |
2335 | console_unlock(); | |
2336 | } | |
2337 | ||
2338 | /* | |
2339 | * Return the console tty driver structure and its associated index | |
2340 | */ | |
2341 | struct tty_driver *console_device(int *index) | |
2342 | { | |
2343 | struct console *c; | |
2344 | struct tty_driver *driver = NULL; | |
2345 | ||
2346 | console_lock(); | |
2347 | for_each_console(c) { | |
2348 | if (!c->device) | |
2349 | continue; | |
2350 | driver = c->device(c, index); | |
2351 | if (driver) | |
2352 | break; | |
2353 | } | |
2354 | console_unlock(); | |
2355 | return driver; | |
2356 | } | |
2357 | ||
2358 | /* | |
2359 | * Prevent further output on the passed console device so that (for example) | |
2360 | * serial drivers can disable console output before suspending a port, and can | |
2361 | * re-enable output afterwards. | |
2362 | */ | |
2363 | void console_stop(struct console *console) | |
2364 | { | |
2365 | console_lock(); | |
2366 | console->flags &= ~CON_ENABLED; | |
2367 | console_unlock(); | |
2368 | } | |
2369 | EXPORT_SYMBOL(console_stop); | |
2370 | ||
2371 | void console_start(struct console *console) | |
2372 | { | |
2373 | console_lock(); | |
2374 | console->flags |= CON_ENABLED; | |
2375 | console_unlock(); | |
2376 | } | |
2377 | EXPORT_SYMBOL(console_start); | |
2378 | ||
2379 | static int __read_mostly keep_bootcon; | |
2380 | ||
2381 | static int __init keep_bootcon_setup(char *str) | |
2382 | { | |
2383 | keep_bootcon = 1; | |
2384 | pr_info("debug: skip boot console de-registration.\n"); | |
2385 | ||
2386 | return 0; | |
2387 | } | |
2388 | ||
2389 | early_param("keep_bootcon", keep_bootcon_setup); | |
2390 | ||
2391 | /* | |
2392 | * The console driver calls this routine during kernel initialization | |
2393 | * to register the console printing procedure with printk() and to | |
2394 | * print any messages that were printed by the kernel before the | |
2395 | * console driver was initialized. | |
2396 | * | |
2397 | * This can happen pretty early during the boot process (because of | |
2398 | * early_printk) - sometimes before setup_arch() completes - be careful | |
2399 | * of what kernel features are used - they may not be initialised yet. | |
2400 | * | |
2401 | * There are two types of consoles - bootconsoles (early_printk) and | |
2402 | * "real" consoles (everything which is not a bootconsole) which are | |
2403 | * handled differently. | |
2404 | * - Any number of bootconsoles can be registered at any time. | |
2405 | * - As soon as a "real" console is registered, all bootconsoles | |
2406 | * will be unregistered automatically. | |
2407 | * - Once a "real" console is registered, any attempt to register a | |
2408 | * bootconsoles will be rejected | |
2409 | */ | |
2410 | void register_console(struct console *newcon) | |
2411 | { | |
2412 | int i; | |
2413 | unsigned long flags; | |
2414 | struct console *bcon = NULL; | |
2415 | struct console_cmdline *c; | |
2416 | static bool has_preferred; | |
2417 | ||
2418 | if (console_drivers) | |
2419 | for_each_console(bcon) | |
2420 | if (WARN(bcon == newcon, | |
2421 | "console '%s%d' already registered\n", | |
2422 | bcon->name, bcon->index)) | |
2423 | return; | |
2424 | ||
2425 | /* | |
2426 | * before we register a new CON_BOOT console, make sure we don't | |
2427 | * already have a valid console | |
2428 | */ | |
2429 | if (console_drivers && newcon->flags & CON_BOOT) { | |
2430 | /* find the last or real console */ | |
2431 | for_each_console(bcon) { | |
2432 | if (!(bcon->flags & CON_BOOT)) { | |
2433 | pr_info("Too late to register bootconsole %s%d\n", | |
2434 | newcon->name, newcon->index); | |
2435 | return; | |
2436 | } | |
2437 | } | |
2438 | } | |
2439 | ||
2440 | if (console_drivers && console_drivers->flags & CON_BOOT) | |
2441 | bcon = console_drivers; | |
2442 | ||
2443 | if (!has_preferred || bcon || !console_drivers) | |
2444 | has_preferred = preferred_console >= 0; | |
2445 | ||
2446 | /* | |
2447 | * See if we want to use this console driver. If we | |
2448 | * didn't select a console we take the first one | |
2449 | * that registers here. | |
2450 | */ | |
2451 | if (!has_preferred) { | |
2452 | if (newcon->index < 0) | |
2453 | newcon->index = 0; | |
2454 | if (newcon->setup == NULL || | |
2455 | newcon->setup(newcon, NULL) == 0) { | |
2456 | newcon->flags |= CON_ENABLED; | |
2457 | if (newcon->device) { | |
2458 | newcon->flags |= CON_CONSDEV; | |
2459 | has_preferred = true; | |
2460 | } | |
2461 | } | |
2462 | } | |
2463 | ||
2464 | /* | |
2465 | * See if this console matches one we selected on | |
2466 | * the command line. | |
2467 | */ | |
2468 | for (i = 0, c = console_cmdline; | |
2469 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2470 | i++, c++) { | |
2471 | if (!newcon->match || | |
2472 | newcon->match(newcon, c->name, c->index, c->options) != 0) { | |
2473 | /* default matching */ | |
2474 | BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name)); | |
2475 | if (strcmp(c->name, newcon->name) != 0) | |
2476 | continue; | |
2477 | if (newcon->index >= 0 && | |
2478 | newcon->index != c->index) | |
2479 | continue; | |
2480 | if (newcon->index < 0) | |
2481 | newcon->index = c->index; | |
2482 | ||
2483 | if (_braille_register_console(newcon, c)) | |
2484 | return; | |
2485 | ||
2486 | if (newcon->setup && | |
2487 | newcon->setup(newcon, c->options) != 0) | |
2488 | break; | |
2489 | } | |
2490 | ||
2491 | newcon->flags |= CON_ENABLED; | |
2492 | if (i == preferred_console) { | |
2493 | newcon->flags |= CON_CONSDEV; | |
2494 | has_preferred = true; | |
2495 | } | |
2496 | break; | |
2497 | } | |
2498 | ||
2499 | if (!(newcon->flags & CON_ENABLED)) | |
2500 | return; | |
2501 | ||
2502 | /* | |
2503 | * If we have a bootconsole, and are switching to a real console, | |
2504 | * don't print everything out again, since when the boot console, and | |
2505 | * the real console are the same physical device, it's annoying to | |
2506 | * see the beginning boot messages twice | |
2507 | */ | |
2508 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
2509 | newcon->flags &= ~CON_PRINTBUFFER; | |
2510 | ||
2511 | /* | |
2512 | * Put this console in the list - keep the | |
2513 | * preferred driver at the head of the list. | |
2514 | */ | |
2515 | console_lock(); | |
2516 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { | |
2517 | newcon->next = console_drivers; | |
2518 | console_drivers = newcon; | |
2519 | if (newcon->next) | |
2520 | newcon->next->flags &= ~CON_CONSDEV; | |
2521 | } else { | |
2522 | newcon->next = console_drivers->next; | |
2523 | console_drivers->next = newcon; | |
2524 | } | |
2525 | ||
2526 | if (newcon->flags & CON_EXTENDED) | |
2527 | if (!nr_ext_console_drivers++) | |
2528 | pr_info("printk: continuation disabled due to ext consoles, expect more fragments in /dev/kmsg\n"); | |
2529 | ||
2530 | if (newcon->flags & CON_PRINTBUFFER) { | |
2531 | /* | |
2532 | * console_unlock(); will print out the buffered messages | |
2533 | * for us. | |
2534 | */ | |
2535 | logbuf_lock_irqsave(flags); | |
2536 | console_seq = syslog_seq; | |
2537 | console_idx = syslog_idx; | |
2538 | logbuf_unlock_irqrestore(flags); | |
2539 | /* | |
2540 | * We're about to replay the log buffer. Only do this to the | |
2541 | * just-registered console to avoid excessive message spam to | |
2542 | * the already-registered consoles. | |
2543 | */ | |
2544 | exclusive_console = newcon; | |
2545 | } | |
2546 | console_unlock(); | |
2547 | console_sysfs_notify(); | |
2548 | ||
2549 | /* | |
2550 | * By unregistering the bootconsoles after we enable the real console | |
2551 | * we get the "console xxx enabled" message on all the consoles - | |
2552 | * boot consoles, real consoles, etc - this is to ensure that end | |
2553 | * users know there might be something in the kernel's log buffer that | |
2554 | * went to the bootconsole (that they do not see on the real console) | |
2555 | */ | |
2556 | pr_info("%sconsole [%s%d] enabled\n", | |
2557 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
2558 | newcon->name, newcon->index); | |
2559 | if (bcon && | |
2560 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && | |
2561 | !keep_bootcon) { | |
2562 | /* We need to iterate through all boot consoles, to make | |
2563 | * sure we print everything out, before we unregister them. | |
2564 | */ | |
2565 | for_each_console(bcon) | |
2566 | if (bcon->flags & CON_BOOT) | |
2567 | unregister_console(bcon); | |
2568 | } | |
2569 | } | |
2570 | EXPORT_SYMBOL(register_console); | |
2571 | ||
2572 | int unregister_console(struct console *console) | |
2573 | { | |
2574 | struct console *a, *b; | |
2575 | int res; | |
2576 | ||
2577 | pr_info("%sconsole [%s%d] disabled\n", | |
2578 | (console->flags & CON_BOOT) ? "boot" : "" , | |
2579 | console->name, console->index); | |
2580 | ||
2581 | res = _braille_unregister_console(console); | |
2582 | if (res) | |
2583 | return res; | |
2584 | ||
2585 | res = 1; | |
2586 | console_lock(); | |
2587 | if (console_drivers == console) { | |
2588 | console_drivers=console->next; | |
2589 | res = 0; | |
2590 | } else if (console_drivers) { | |
2591 | for (a=console_drivers->next, b=console_drivers ; | |
2592 | a; b=a, a=b->next) { | |
2593 | if (a == console) { | |
2594 | b->next = a->next; | |
2595 | res = 0; | |
2596 | break; | |
2597 | } | |
2598 | } | |
2599 | } | |
2600 | ||
2601 | if (!res && (console->flags & CON_EXTENDED)) | |
2602 | nr_ext_console_drivers--; | |
2603 | ||
2604 | /* | |
2605 | * If this isn't the last console and it has CON_CONSDEV set, we | |
2606 | * need to set it on the next preferred console. | |
2607 | */ | |
2608 | if (console_drivers != NULL && console->flags & CON_CONSDEV) | |
2609 | console_drivers->flags |= CON_CONSDEV; | |
2610 | ||
2611 | console->flags &= ~CON_ENABLED; | |
2612 | console_unlock(); | |
2613 | console_sysfs_notify(); | |
2614 | return res; | |
2615 | } | |
2616 | EXPORT_SYMBOL(unregister_console); | |
2617 | ||
2618 | /* | |
2619 | * Initialize the console device. This is called *early*, so | |
2620 | * we can't necessarily depend on lots of kernel help here. | |
2621 | * Just do some early initializations, and do the complex setup | |
2622 | * later. | |
2623 | */ | |
2624 | void __init console_init(void) | |
2625 | { | |
2626 | initcall_t *call; | |
2627 | ||
2628 | /* Setup the default TTY line discipline. */ | |
2629 | n_tty_init(); | |
2630 | ||
2631 | /* | |
2632 | * set up the console device so that later boot sequences can | |
2633 | * inform about problems etc.. | |
2634 | */ | |
2635 | call = __con_initcall_start; | |
2636 | while (call < __con_initcall_end) { | |
2637 | (*call)(); | |
2638 | call++; | |
2639 | } | |
2640 | } | |
2641 | ||
2642 | /* | |
2643 | * Some boot consoles access data that is in the init section and which will | |
2644 | * be discarded after the initcalls have been run. To make sure that no code | |
2645 | * will access this data, unregister the boot consoles in a late initcall. | |
2646 | * | |
2647 | * If for some reason, such as deferred probe or the driver being a loadable | |
2648 | * module, the real console hasn't registered yet at this point, there will | |
2649 | * be a brief interval in which no messages are logged to the console, which | |
2650 | * makes it difficult to diagnose problems that occur during this time. | |
2651 | * | |
2652 | * To mitigate this problem somewhat, only unregister consoles whose memory | |
2653 | * intersects with the init section. Note that code exists elsewhere to get | |
2654 | * rid of the boot console as soon as the proper console shows up, so there | |
2655 | * won't be side-effects from postponing the removal. | |
2656 | */ | |
2657 | static int __init printk_late_init(void) | |
2658 | { | |
2659 | struct console *con; | |
2660 | int ret; | |
2661 | ||
2662 | for_each_console(con) { | |
2663 | if (!keep_bootcon && con->flags & CON_BOOT) { | |
2664 | /* | |
2665 | * Make sure to unregister boot consoles whose data | |
2666 | * resides in the init section before the init section | |
2667 | * is discarded. Boot consoles whose data will stick | |
2668 | * around will automatically be unregistered when the | |
2669 | * proper console replaces them. | |
2670 | */ | |
2671 | if (init_section_intersects(con, sizeof(*con))) | |
2672 | unregister_console(con); | |
2673 | } | |
2674 | } | |
2675 | ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL, | |
2676 | console_cpu_notify); | |
2677 | WARN_ON(ret < 0); | |
2678 | ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "printk:online", | |
2679 | console_cpu_notify, NULL); | |
2680 | WARN_ON(ret < 0); | |
2681 | return 0; | |
2682 | } | |
2683 | late_initcall(printk_late_init); | |
2684 | ||
2685 | #if defined CONFIG_PRINTK | |
2686 | /* | |
2687 | * Delayed printk version, for scheduler-internal messages: | |
2688 | */ | |
2689 | #define PRINTK_PENDING_WAKEUP 0x01 | |
2690 | #define PRINTK_PENDING_OUTPUT 0x02 | |
2691 | ||
2692 | static DEFINE_PER_CPU(int, printk_pending); | |
2693 | ||
2694 | static void wake_up_klogd_work_func(struct irq_work *irq_work) | |
2695 | { | |
2696 | int pending = __this_cpu_xchg(printk_pending, 0); | |
2697 | ||
2698 | if (pending & PRINTK_PENDING_OUTPUT) { | |
2699 | /* If trylock fails, someone else is doing the printing */ | |
2700 | if (console_trylock()) | |
2701 | console_unlock(); | |
2702 | } | |
2703 | ||
2704 | if (pending & PRINTK_PENDING_WAKEUP) | |
2705 | wake_up_interruptible(&log_wait); | |
2706 | } | |
2707 | ||
2708 | static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { | |
2709 | .func = wake_up_klogd_work_func, | |
2710 | .flags = IRQ_WORK_LAZY, | |
2711 | }; | |
2712 | ||
2713 | void wake_up_klogd(void) | |
2714 | { | |
2715 | preempt_disable(); | |
2716 | if (waitqueue_active(&log_wait)) { | |
2717 | this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); | |
2718 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); | |
2719 | } | |
2720 | preempt_enable(); | |
2721 | } | |
2722 | ||
2723 | int printk_deferred(const char *fmt, ...) | |
2724 | { | |
2725 | va_list args; | |
2726 | int r; | |
2727 | ||
2728 | preempt_disable(); | |
2729 | va_start(args, fmt); | |
2730 | r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args); | |
2731 | va_end(args); | |
2732 | ||
2733 | __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); | |
2734 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); | |
2735 | preempt_enable(); | |
2736 | ||
2737 | return r; | |
2738 | } | |
2739 | ||
2740 | /* | |
2741 | * printk rate limiting, lifted from the networking subsystem. | |
2742 | * | |
2743 | * This enforces a rate limit: not more than 10 kernel messages | |
2744 | * every 5s to make a denial-of-service attack impossible. | |
2745 | */ | |
2746 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); | |
2747 | ||
2748 | int __printk_ratelimit(const char *func) | |
2749 | { | |
2750 | return ___ratelimit(&printk_ratelimit_state, func); | |
2751 | } | |
2752 | EXPORT_SYMBOL(__printk_ratelimit); | |
2753 | ||
2754 | /** | |
2755 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
2756 | * @caller_jiffies: pointer to caller's state | |
2757 | * @interval_msecs: minimum interval between prints | |
2758 | * | |
2759 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
2760 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
2761 | * returned true. | |
2762 | */ | |
2763 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
2764 | unsigned int interval_msecs) | |
2765 | { | |
2766 | unsigned long elapsed = jiffies - *caller_jiffies; | |
2767 | ||
2768 | if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) | |
2769 | return false; | |
2770 | ||
2771 | *caller_jiffies = jiffies; | |
2772 | return true; | |
2773 | } | |
2774 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
2775 | ||
2776 | static DEFINE_SPINLOCK(dump_list_lock); | |
2777 | static LIST_HEAD(dump_list); | |
2778 | ||
2779 | /** | |
2780 | * kmsg_dump_register - register a kernel log dumper. | |
2781 | * @dumper: pointer to the kmsg_dumper structure | |
2782 | * | |
2783 | * Adds a kernel log dumper to the system. The dump callback in the | |
2784 | * structure will be called when the kernel oopses or panics and must be | |
2785 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
2786 | */ | |
2787 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
2788 | { | |
2789 | unsigned long flags; | |
2790 | int err = -EBUSY; | |
2791 | ||
2792 | /* The dump callback needs to be set */ | |
2793 | if (!dumper->dump) | |
2794 | return -EINVAL; | |
2795 | ||
2796 | spin_lock_irqsave(&dump_list_lock, flags); | |
2797 | /* Don't allow registering multiple times */ | |
2798 | if (!dumper->registered) { | |
2799 | dumper->registered = 1; | |
2800 | list_add_tail_rcu(&dumper->list, &dump_list); | |
2801 | err = 0; | |
2802 | } | |
2803 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
2804 | ||
2805 | return err; | |
2806 | } | |
2807 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
2808 | ||
2809 | /** | |
2810 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
2811 | * @dumper: pointer to the kmsg_dumper structure | |
2812 | * | |
2813 | * Removes a dump device from the system. Returns zero on success and | |
2814 | * %-EINVAL otherwise. | |
2815 | */ | |
2816 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
2817 | { | |
2818 | unsigned long flags; | |
2819 | int err = -EINVAL; | |
2820 | ||
2821 | spin_lock_irqsave(&dump_list_lock, flags); | |
2822 | if (dumper->registered) { | |
2823 | dumper->registered = 0; | |
2824 | list_del_rcu(&dumper->list); | |
2825 | err = 0; | |
2826 | } | |
2827 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
2828 | synchronize_rcu(); | |
2829 | ||
2830 | return err; | |
2831 | } | |
2832 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
2833 | ||
2834 | static bool always_kmsg_dump; | |
2835 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); | |
2836 | ||
2837 | /** | |
2838 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
2839 | * @reason: the reason (oops, panic etc) for dumping | |
2840 | * | |
2841 | * Call each of the registered dumper's dump() callback, which can | |
2842 | * retrieve the kmsg records with kmsg_dump_get_line() or | |
2843 | * kmsg_dump_get_buffer(). | |
2844 | */ | |
2845 | void kmsg_dump(enum kmsg_dump_reason reason) | |
2846 | { | |
2847 | struct kmsg_dumper *dumper; | |
2848 | unsigned long flags; | |
2849 | ||
2850 | if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump) | |
2851 | return; | |
2852 | ||
2853 | rcu_read_lock(); | |
2854 | list_for_each_entry_rcu(dumper, &dump_list, list) { | |
2855 | if (dumper->max_reason && reason > dumper->max_reason) | |
2856 | continue; | |
2857 | ||
2858 | /* initialize iterator with data about the stored records */ | |
2859 | dumper->active = true; | |
2860 | ||
2861 | logbuf_lock_irqsave(flags); | |
2862 | dumper->cur_seq = clear_seq; | |
2863 | dumper->cur_idx = clear_idx; | |
2864 | dumper->next_seq = log_next_seq; | |
2865 | dumper->next_idx = log_next_idx; | |
2866 | logbuf_unlock_irqrestore(flags); | |
2867 | ||
2868 | /* invoke dumper which will iterate over records */ | |
2869 | dumper->dump(dumper, reason); | |
2870 | ||
2871 | /* reset iterator */ | |
2872 | dumper->active = false; | |
2873 | } | |
2874 | rcu_read_unlock(); | |
2875 | } | |
2876 | ||
2877 | /** | |
2878 | * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version) | |
2879 | * @dumper: registered kmsg dumper | |
2880 | * @syslog: include the "<4>" prefixes | |
2881 | * @line: buffer to copy the line to | |
2882 | * @size: maximum size of the buffer | |
2883 | * @len: length of line placed into buffer | |
2884 | * | |
2885 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
2886 | * record, and copy one record into the provided buffer. | |
2887 | * | |
2888 | * Consecutive calls will return the next available record moving | |
2889 | * towards the end of the buffer with the youngest messages. | |
2890 | * | |
2891 | * A return value of FALSE indicates that there are no more records to | |
2892 | * read. | |
2893 | * | |
2894 | * The function is similar to kmsg_dump_get_line(), but grabs no locks. | |
2895 | */ | |
2896 | bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog, | |
2897 | char *line, size_t size, size_t *len) | |
2898 | { | |
2899 | struct printk_log *msg; | |
2900 | size_t l = 0; | |
2901 | bool ret = false; | |
2902 | ||
2903 | if (!dumper->active) | |
2904 | goto out; | |
2905 | ||
2906 | if (dumper->cur_seq < log_first_seq) { | |
2907 | /* messages are gone, move to first available one */ | |
2908 | dumper->cur_seq = log_first_seq; | |
2909 | dumper->cur_idx = log_first_idx; | |
2910 | } | |
2911 | ||
2912 | /* last entry */ | |
2913 | if (dumper->cur_seq >= log_next_seq) | |
2914 | goto out; | |
2915 | ||
2916 | msg = log_from_idx(dumper->cur_idx); | |
2917 | l = msg_print_text(msg, syslog, line, size); | |
2918 | ||
2919 | dumper->cur_idx = log_next(dumper->cur_idx); | |
2920 | dumper->cur_seq++; | |
2921 | ret = true; | |
2922 | out: | |
2923 | if (len) | |
2924 | *len = l; | |
2925 | return ret; | |
2926 | } | |
2927 | ||
2928 | /** | |
2929 | * kmsg_dump_get_line - retrieve one kmsg log line | |
2930 | * @dumper: registered kmsg dumper | |
2931 | * @syslog: include the "<4>" prefixes | |
2932 | * @line: buffer to copy the line to | |
2933 | * @size: maximum size of the buffer | |
2934 | * @len: length of line placed into buffer | |
2935 | * | |
2936 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
2937 | * record, and copy one record into the provided buffer. | |
2938 | * | |
2939 | * Consecutive calls will return the next available record moving | |
2940 | * towards the end of the buffer with the youngest messages. | |
2941 | * | |
2942 | * A return value of FALSE indicates that there are no more records to | |
2943 | * read. | |
2944 | */ | |
2945 | bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, | |
2946 | char *line, size_t size, size_t *len) | |
2947 | { | |
2948 | unsigned long flags; | |
2949 | bool ret; | |
2950 | ||
2951 | logbuf_lock_irqsave(flags); | |
2952 | ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len); | |
2953 | logbuf_unlock_irqrestore(flags); | |
2954 | ||
2955 | return ret; | |
2956 | } | |
2957 | EXPORT_SYMBOL_GPL(kmsg_dump_get_line); | |
2958 | ||
2959 | /** | |
2960 | * kmsg_dump_get_buffer - copy kmsg log lines | |
2961 | * @dumper: registered kmsg dumper | |
2962 | * @syslog: include the "<4>" prefixes | |
2963 | * @buf: buffer to copy the line to | |
2964 | * @size: maximum size of the buffer | |
2965 | * @len: length of line placed into buffer | |
2966 | * | |
2967 | * Start at the end of the kmsg buffer and fill the provided buffer | |
2968 | * with as many of the the *youngest* kmsg records that fit into it. | |
2969 | * If the buffer is large enough, all available kmsg records will be | |
2970 | * copied with a single call. | |
2971 | * | |
2972 | * Consecutive calls will fill the buffer with the next block of | |
2973 | * available older records, not including the earlier retrieved ones. | |
2974 | * | |
2975 | * A return value of FALSE indicates that there are no more records to | |
2976 | * read. | |
2977 | */ | |
2978 | bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, | |
2979 | char *buf, size_t size, size_t *len) | |
2980 | { | |
2981 | unsigned long flags; | |
2982 | u64 seq; | |
2983 | u32 idx; | |
2984 | u64 next_seq; | |
2985 | u32 next_idx; | |
2986 | size_t l = 0; | |
2987 | bool ret = false; | |
2988 | ||
2989 | if (!dumper->active) | |
2990 | goto out; | |
2991 | ||
2992 | logbuf_lock_irqsave(flags); | |
2993 | if (dumper->cur_seq < log_first_seq) { | |
2994 | /* messages are gone, move to first available one */ | |
2995 | dumper->cur_seq = log_first_seq; | |
2996 | dumper->cur_idx = log_first_idx; | |
2997 | } | |
2998 | ||
2999 | /* last entry */ | |
3000 | if (dumper->cur_seq >= dumper->next_seq) { | |
3001 | logbuf_unlock_irqrestore(flags); | |
3002 | goto out; | |
3003 | } | |
3004 | ||
3005 | /* calculate length of entire buffer */ | |
3006 | seq = dumper->cur_seq; | |
3007 | idx = dumper->cur_idx; | |
3008 | while (seq < dumper->next_seq) { | |
3009 | struct printk_log *msg = log_from_idx(idx); | |
3010 | ||
3011 | l += msg_print_text(msg, true, NULL, 0); | |
3012 | idx = log_next(idx); | |
3013 | seq++; | |
3014 | } | |
3015 | ||
3016 | /* move first record forward until length fits into the buffer */ | |
3017 | seq = dumper->cur_seq; | |
3018 | idx = dumper->cur_idx; | |
3019 | while (l > size && seq < dumper->next_seq) { | |
3020 | struct printk_log *msg = log_from_idx(idx); | |
3021 | ||
3022 | l -= msg_print_text(msg, true, NULL, 0); | |
3023 | idx = log_next(idx); | |
3024 | seq++; | |
3025 | } | |
3026 | ||
3027 | /* last message in next interation */ | |
3028 | next_seq = seq; | |
3029 | next_idx = idx; | |
3030 | ||
3031 | l = 0; | |
3032 | while (seq < dumper->next_seq) { | |
3033 | struct printk_log *msg = log_from_idx(idx); | |
3034 | ||
3035 | l += msg_print_text(msg, syslog, buf + l, size - l); | |
3036 | idx = log_next(idx); | |
3037 | seq++; | |
3038 | } | |
3039 | ||
3040 | dumper->next_seq = next_seq; | |
3041 | dumper->next_idx = next_idx; | |
3042 | ret = true; | |
3043 | logbuf_unlock_irqrestore(flags); | |
3044 | out: | |
3045 | if (len) | |
3046 | *len = l; | |
3047 | return ret; | |
3048 | } | |
3049 | EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); | |
3050 | ||
3051 | /** | |
3052 | * kmsg_dump_rewind_nolock - reset the interator (unlocked version) | |
3053 | * @dumper: registered kmsg dumper | |
3054 | * | |
3055 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
3056 | * kmsg_dump_get_buffer() can be called again and used multiple | |
3057 | * times within the same dumper.dump() callback. | |
3058 | * | |
3059 | * The function is similar to kmsg_dump_rewind(), but grabs no locks. | |
3060 | */ | |
3061 | void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper) | |
3062 | { | |
3063 | dumper->cur_seq = clear_seq; | |
3064 | dumper->cur_idx = clear_idx; | |
3065 | dumper->next_seq = log_next_seq; | |
3066 | dumper->next_idx = log_next_idx; | |
3067 | } | |
3068 | ||
3069 | /** | |
3070 | * kmsg_dump_rewind - reset the interator | |
3071 | * @dumper: registered kmsg dumper | |
3072 | * | |
3073 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
3074 | * kmsg_dump_get_buffer() can be called again and used multiple | |
3075 | * times within the same dumper.dump() callback. | |
3076 | */ | |
3077 | void kmsg_dump_rewind(struct kmsg_dumper *dumper) | |
3078 | { | |
3079 | unsigned long flags; | |
3080 | ||
3081 | logbuf_lock_irqsave(flags); | |
3082 | kmsg_dump_rewind_nolock(dumper); | |
3083 | logbuf_unlock_irqrestore(flags); | |
3084 | } | |
3085 | EXPORT_SYMBOL_GPL(kmsg_dump_rewind); | |
3086 | ||
3087 | static char dump_stack_arch_desc_str[128]; | |
3088 | ||
3089 | /** | |
3090 | * dump_stack_set_arch_desc - set arch-specific str to show with task dumps | |
3091 | * @fmt: printf-style format string | |
3092 | * @...: arguments for the format string | |
3093 | * | |
3094 | * The configured string will be printed right after utsname during task | |
3095 | * dumps. Usually used to add arch-specific system identifiers. If an | |
3096 | * arch wants to make use of such an ID string, it should initialize this | |
3097 | * as soon as possible during boot. | |
3098 | */ | |
3099 | void __init dump_stack_set_arch_desc(const char *fmt, ...) | |
3100 | { | |
3101 | va_list args; | |
3102 | ||
3103 | va_start(args, fmt); | |
3104 | vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str), | |
3105 | fmt, args); | |
3106 | va_end(args); | |
3107 | } | |
3108 | ||
3109 | /** | |
3110 | * dump_stack_print_info - print generic debug info for dump_stack() | |
3111 | * @log_lvl: log level | |
3112 | * | |
3113 | * Arch-specific dump_stack() implementations can use this function to | |
3114 | * print out the same debug information as the generic dump_stack(). | |
3115 | */ | |
3116 | void dump_stack_print_info(const char *log_lvl) | |
3117 | { | |
3118 | printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n", | |
3119 | log_lvl, raw_smp_processor_id(), current->pid, current->comm, | |
3120 | print_tainted(), init_utsname()->release, | |
3121 | (int)strcspn(init_utsname()->version, " "), | |
3122 | init_utsname()->version); | |
3123 | ||
3124 | if (dump_stack_arch_desc_str[0] != '\0') | |
3125 | printk("%sHardware name: %s\n", | |
3126 | log_lvl, dump_stack_arch_desc_str); | |
3127 | ||
3128 | print_worker_info(log_lvl, current); | |
3129 | } | |
3130 | ||
3131 | /** | |
3132 | * show_regs_print_info - print generic debug info for show_regs() | |
3133 | * @log_lvl: log level | |
3134 | * | |
3135 | * show_regs() implementations can use this function to print out generic | |
3136 | * debug information. | |
3137 | */ | |
3138 | void show_regs_print_info(const char *log_lvl) | |
3139 | { | |
3140 | dump_stack_print_info(log_lvl); | |
3141 | ||
3142 | printk("%stask: %p task.stack: %p\n", | |
3143 | log_lvl, current, task_stack_page(current)); | |
3144 | } | |
3145 | ||
3146 | #endif |