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-rw-r--r--kernel/printk/printk.c2910
1 files changed, 2910 insertions, 0 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
new file mode 100644
index 000000000000..b4e8500afdb3
--- /dev/null
+++ b/kernel/printk/printk.c
@@ -0,0 +1,2910 @@
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/interrupt.h> /* For in_interrupt() */
30#include <linux/delay.h>
31#include <linux/smp.h>
32#include <linux/security.h>
33#include <linux/bootmem.h>
34#include <linux/memblock.h>
35#include <linux/aio.h>
36#include <linux/syscalls.h>
37#include <linux/kexec.h>
38#include <linux/kdb.h>
39#include <linux/ratelimit.h>
40#include <linux/kmsg_dump.h>
41#include <linux/syslog.h>
42#include <linux/cpu.h>
43#include <linux/notifier.h>
44#include <linux/rculist.h>
45#include <linux/poll.h>
46#include <linux/irq_work.h>
47#include <linux/utsname.h>
48
49#include <asm/uaccess.h>
50
51#define CREATE_TRACE_POINTS
52#include <trace/events/printk.h>
53
54#include "console_cmdline.h"
55#include "braille.h"
56
57/* printk's without a loglevel use this.. */
58#define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
59
60/* We show everything that is MORE important than this.. */
61#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
62#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
63
64int console_printk[4] = {
65 DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
66 DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
67 MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */
68 DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
69};
70
71/*
72 * Low level drivers may need that to know if they can schedule in
73 * their unblank() callback or not. So let's export it.
74 */
75int oops_in_progress;
76EXPORT_SYMBOL(oops_in_progress);
77
78/*
79 * console_sem protects the console_drivers list, and also
80 * provides serialisation for access to the entire console
81 * driver system.
82 */
83static DEFINE_SEMAPHORE(console_sem);
84struct console *console_drivers;
85EXPORT_SYMBOL_GPL(console_drivers);
86
87#ifdef CONFIG_LOCKDEP
88static struct lockdep_map console_lock_dep_map = {
89 .name = "console_lock"
90};
91#endif
92
93/*
94 * This is used for debugging the mess that is the VT code by
95 * keeping track if we have the console semaphore held. It's
96 * definitely not the perfect debug tool (we don't know if _WE_
97 * hold it are racing, but it helps tracking those weird code
98 * path in the console code where we end up in places I want
99 * locked without the console sempahore held
100 */
101static int console_locked, console_suspended;
102
103/*
104 * If exclusive_console is non-NULL then only this console is to be printed to.
105 */
106static struct console *exclusive_console;
107
108/*
109 * Array of consoles built from command line options (console=)
110 */
111
112#define MAX_CMDLINECONSOLES 8
113
114static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
115
116static int selected_console = -1;
117static int preferred_console = -1;
118int console_set_on_cmdline;
119EXPORT_SYMBOL(console_set_on_cmdline);
120
121/* Flag: console code may call schedule() */
122static int console_may_schedule;
123
124/*
125 * The printk log buffer consists of a chain of concatenated variable
126 * length records. Every record starts with a record header, containing
127 * the overall length of the record.
128 *
129 * The heads to the first and last entry in the buffer, as well as the
130 * sequence numbers of these both entries are maintained when messages
131 * are stored..
132 *
133 * If the heads indicate available messages, the length in the header
134 * tells the start next message. A length == 0 for the next message
135 * indicates a wrap-around to the beginning of the buffer.
136 *
137 * Every record carries the monotonic timestamp in microseconds, as well as
138 * the standard userspace syslog level and syslog facility. The usual
139 * kernel messages use LOG_KERN; userspace-injected messages always carry
140 * a matching syslog facility, by default LOG_USER. The origin of every
141 * message can be reliably determined that way.
142 *
143 * The human readable log message directly follows the message header. The
144 * length of the message text is stored in the header, the stored message
145 * is not terminated.
146 *
147 * Optionally, a message can carry a dictionary of properties (key/value pairs),
148 * to provide userspace with a machine-readable message context.
149 *
150 * Examples for well-defined, commonly used property names are:
151 * DEVICE=b12:8 device identifier
152 * b12:8 block dev_t
153 * c127:3 char dev_t
154 * n8 netdev ifindex
155 * +sound:card0 subsystem:devname
156 * SUBSYSTEM=pci driver-core subsystem name
157 *
158 * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
159 * follows directly after a '=' character. Every property is terminated by
160 * a '\0' character. The last property is not terminated.
161 *
162 * Example of a message structure:
163 * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec
164 * 0008 34 00 record is 52 bytes long
165 * 000a 0b 00 text is 11 bytes long
166 * 000c 1f 00 dictionary is 23 bytes long
167 * 000e 03 00 LOG_KERN (facility) LOG_ERR (level)
168 * 0010 69 74 27 73 20 61 20 6c "it's a l"
169 * 69 6e 65 "ine"
170 * 001b 44 45 56 49 43 "DEVIC"
171 * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D"
172 * 52 49 56 45 52 3d 62 75 "RIVER=bu"
173 * 67 "g"
174 * 0032 00 00 00 padding to next message header
175 *
176 * The 'struct printk_log' buffer header must never be directly exported to
177 * userspace, it is a kernel-private implementation detail that might
178 * need to be changed in the future, when the requirements change.
179 *
180 * /dev/kmsg exports the structured data in the following line format:
181 * "level,sequnum,timestamp;<message text>\n"
182 *
183 * The optional key/value pairs are attached as continuation lines starting
184 * with a space character and terminated by a newline. All possible
185 * non-prinatable characters are escaped in the "\xff" notation.
186 *
187 * Users of the export format should ignore possible additional values
188 * separated by ',', and find the message after the ';' character.
189 */
190
191enum log_flags {
192 LOG_NOCONS = 1, /* already flushed, do not print to console */
193 LOG_NEWLINE = 2, /* text ended with a newline */
194 LOG_PREFIX = 4, /* text started with a prefix */
195 LOG_CONT = 8, /* text is a fragment of a continuation line */
196};
197
198struct printk_log {
199 u64 ts_nsec; /* timestamp in nanoseconds */
200 u16 len; /* length of entire record */
201 u16 text_len; /* length of text buffer */
202 u16 dict_len; /* length of dictionary buffer */
203 u8 facility; /* syslog facility */
204 u8 flags:5; /* internal record flags */
205 u8 level:3; /* syslog level */
206};
207
208/*
209 * The logbuf_lock protects kmsg buffer, indices, counters. It is also
210 * used in interesting ways to provide interlocking in console_unlock();
211 */
212static DEFINE_RAW_SPINLOCK(logbuf_lock);
213
214#ifdef CONFIG_PRINTK
215DECLARE_WAIT_QUEUE_HEAD(log_wait);
216/* the next printk record to read by syslog(READ) or /proc/kmsg */
217static u64 syslog_seq;
218static u32 syslog_idx;
219static enum log_flags syslog_prev;
220static size_t syslog_partial;
221
222/* index and sequence number of the first record stored in the buffer */
223static u64 log_first_seq;
224static u32 log_first_idx;
225
226/* index and sequence number of the next record to store in the buffer */
227static u64 log_next_seq;
228static u32 log_next_idx;
229
230/* the next printk record to write to the console */
231static u64 console_seq;
232static u32 console_idx;
233static enum log_flags console_prev;
234
235/* the next printk record to read after the last 'clear' command */
236static u64 clear_seq;
237static u32 clear_idx;
238
239#define PREFIX_MAX 32
240#define LOG_LINE_MAX 1024 - PREFIX_MAX
241
242/* record buffer */
243#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
244#define LOG_ALIGN 4
245#else
246#define LOG_ALIGN __alignof__(struct printk_log)
247#endif
248#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
249static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
250static char *log_buf = __log_buf;
251static u32 log_buf_len = __LOG_BUF_LEN;
252
253/* cpu currently holding logbuf_lock */
254static volatile unsigned int logbuf_cpu = UINT_MAX;
255
256/* human readable text of the record */
257static char *log_text(const struct printk_log *msg)
258{
259 return (char *)msg + sizeof(struct printk_log);
260}
261
262/* optional key/value pair dictionary attached to the record */
263static char *log_dict(const struct printk_log *msg)
264{
265 return (char *)msg + sizeof(struct printk_log) + msg->text_len;
266}
267
268/* get record by index; idx must point to valid msg */
269static struct printk_log *log_from_idx(u32 idx)
270{
271 struct printk_log *msg = (struct printk_log *)(log_buf + idx);
272
273 /*
274 * A length == 0 record is the end of buffer marker. Wrap around and
275 * read the message at the start of the buffer.
276 */
277 if (!msg->len)
278 return (struct printk_log *)log_buf;
279 return msg;
280}
281
282/* get next record; idx must point to valid msg */
283static u32 log_next(u32 idx)
284{
285 struct printk_log *msg = (struct printk_log *)(log_buf + idx);
286
287 /* length == 0 indicates the end of the buffer; wrap */
288 /*
289 * A length == 0 record is the end of buffer marker. Wrap around and
290 * read the message at the start of the buffer as *this* one, and
291 * return the one after that.
292 */
293 if (!msg->len) {
294 msg = (struct printk_log *)log_buf;
295 return msg->len;
296 }
297 return idx + msg->len;
298}
299
300/* insert record into the buffer, discard old ones, update heads */
301static void log_store(int facility, int level,
302 enum log_flags flags, u64 ts_nsec,
303 const char *dict, u16 dict_len,
304 const char *text, u16 text_len)
305{
306 struct printk_log *msg;
307 u32 size, pad_len;
308
309 /* number of '\0' padding bytes to next message */
310 size = sizeof(struct printk_log) + text_len + dict_len;
311 pad_len = (-size) & (LOG_ALIGN - 1);
312 size += pad_len;
313
314 while (log_first_seq < log_next_seq) {
315 u32 free;
316
317 if (log_next_idx > log_first_idx)
318 free = max(log_buf_len - log_next_idx, log_first_idx);
319 else
320 free = log_first_idx - log_next_idx;
321
322 if (free > size + sizeof(struct printk_log))
323 break;
324
325 /* drop old messages until we have enough contiuous space */
326 log_first_idx = log_next(log_first_idx);
327 log_first_seq++;
328 }
329
330 if (log_next_idx + size + sizeof(struct printk_log) >= log_buf_len) {
331 /*
332 * This message + an additional empty header does not fit
333 * at the end of the buffer. Add an empty header with len == 0
334 * to signify a wrap around.
335 */
336 memset(log_buf + log_next_idx, 0, sizeof(struct printk_log));
337 log_next_idx = 0;
338 }
339
340 /* fill message */
341 msg = (struct printk_log *)(log_buf + log_next_idx);
342 memcpy(log_text(msg), text, text_len);
343 msg->text_len = text_len;
344 memcpy(log_dict(msg), dict, dict_len);
345 msg->dict_len = dict_len;
346 msg->facility = facility;
347 msg->level = level & 7;
348 msg->flags = flags & 0x1f;
349 if (ts_nsec > 0)
350 msg->ts_nsec = ts_nsec;
351 else
352 msg->ts_nsec = local_clock();
353 memset(log_dict(msg) + dict_len, 0, pad_len);
354 msg->len = sizeof(struct printk_log) + text_len + dict_len + pad_len;
355
356 /* insert message */
357 log_next_idx += msg->len;
358 log_next_seq++;
359}
360
361#ifdef CONFIG_SECURITY_DMESG_RESTRICT
362int dmesg_restrict = 1;
363#else
364int dmesg_restrict;
365#endif
366
367static int syslog_action_restricted(int type)
368{
369 if (dmesg_restrict)
370 return 1;
371 /*
372 * Unless restricted, we allow "read all" and "get buffer size"
373 * for everybody.
374 */
375 return type != SYSLOG_ACTION_READ_ALL &&
376 type != SYSLOG_ACTION_SIZE_BUFFER;
377}
378
379static int check_syslog_permissions(int type, bool from_file)
380{
381 /*
382 * If this is from /proc/kmsg and we've already opened it, then we've
383 * already done the capabilities checks at open time.
384 */
385 if (from_file && type != SYSLOG_ACTION_OPEN)
386 return 0;
387
388 if (syslog_action_restricted(type)) {
389 if (capable(CAP_SYSLOG))
390 return 0;
391 /*
392 * For historical reasons, accept CAP_SYS_ADMIN too, with
393 * a warning.
394 */
395 if (capable(CAP_SYS_ADMIN)) {
396 pr_warn_once("%s (%d): Attempt to access syslog with "
397 "CAP_SYS_ADMIN but no CAP_SYSLOG "
398 "(deprecated).\n",
399 current->comm, task_pid_nr(current));
400 return 0;
401 }
402 return -EPERM;
403 }
404 return security_syslog(type);
405}
406
407
408/* /dev/kmsg - userspace message inject/listen interface */
409struct devkmsg_user {
410 u64 seq;
411 u32 idx;
412 enum log_flags prev;
413 struct mutex lock;
414 char buf[8192];
415};
416
417static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
418 unsigned long count, loff_t pos)
419{
420 char *buf, *line;
421 int i;
422 int level = default_message_loglevel;
423 int facility = 1; /* LOG_USER */
424 size_t len = iov_length(iv, count);
425 ssize_t ret = len;
426
427 if (len > LOG_LINE_MAX)
428 return -EINVAL;
429 buf = kmalloc(len+1, GFP_KERNEL);
430 if (buf == NULL)
431 return -ENOMEM;
432
433 line = buf;
434 for (i = 0; i < count; i++) {
435 if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) {
436 ret = -EFAULT;
437 goto out;
438 }
439 line += iv[i].iov_len;
440 }
441
442 /*
443 * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
444 * the decimal value represents 32bit, the lower 3 bit are the log
445 * level, the rest are the log facility.
446 *
447 * If no prefix or no userspace facility is specified, we
448 * enforce LOG_USER, to be able to reliably distinguish
449 * kernel-generated messages from userspace-injected ones.
450 */
451 line = buf;
452 if (line[0] == '<') {
453 char *endp = NULL;
454
455 i = simple_strtoul(line+1, &endp, 10);
456 if (endp && endp[0] == '>') {
457 level = i & 7;
458 if (i >> 3)
459 facility = i >> 3;
460 endp++;
461 len -= endp - line;
462 line = endp;
463 }
464 }
465 line[len] = '\0';
466
467 printk_emit(facility, level, NULL, 0, "%s", line);
468out:
469 kfree(buf);
470 return ret;
471}
472
473static ssize_t devkmsg_read(struct file *file, char __user *buf,
474 size_t count, loff_t *ppos)
475{
476 struct devkmsg_user *user = file->private_data;
477 struct printk_log *msg;
478 u64 ts_usec;
479 size_t i;
480 char cont = '-';
481 size_t len;
482 ssize_t ret;
483
484 if (!user)
485 return -EBADF;
486
487 ret = mutex_lock_interruptible(&user->lock);
488 if (ret)
489 return ret;
490 raw_spin_lock_irq(&logbuf_lock);
491 while (user->seq == log_next_seq) {
492 if (file->f_flags & O_NONBLOCK) {
493 ret = -EAGAIN;
494 raw_spin_unlock_irq(&logbuf_lock);
495 goto out;
496 }
497
498 raw_spin_unlock_irq(&logbuf_lock);
499 ret = wait_event_interruptible(log_wait,
500 user->seq != log_next_seq);
501 if (ret)
502 goto out;
503 raw_spin_lock_irq(&logbuf_lock);
504 }
505
506 if (user->seq < log_first_seq) {
507 /* our last seen message is gone, return error and reset */
508 user->idx = log_first_idx;
509 user->seq = log_first_seq;
510 ret = -EPIPE;
511 raw_spin_unlock_irq(&logbuf_lock);
512 goto out;
513 }
514
515 msg = log_from_idx(user->idx);
516 ts_usec = msg->ts_nsec;
517 do_div(ts_usec, 1000);
518
519 /*
520 * If we couldn't merge continuation line fragments during the print,
521 * export the stored flags to allow an optional external merge of the
522 * records. Merging the records isn't always neccessarily correct, like
523 * when we hit a race during printing. In most cases though, it produces
524 * better readable output. 'c' in the record flags mark the first
525 * fragment of a line, '+' the following.
526 */
527 if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT))
528 cont = 'c';
529 else if ((msg->flags & LOG_CONT) ||
530 ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
531 cont = '+';
532
533 len = sprintf(user->buf, "%u,%llu,%llu,%c;",
534 (msg->facility << 3) | msg->level,
535 user->seq, ts_usec, cont);
536 user->prev = msg->flags;
537
538 /* escape non-printable characters */
539 for (i = 0; i < msg->text_len; i++) {
540 unsigned char c = log_text(msg)[i];
541
542 if (c < ' ' || c >= 127 || c == '\\')
543 len += sprintf(user->buf + len, "\\x%02x", c);
544 else
545 user->buf[len++] = c;
546 }
547 user->buf[len++] = '\n';
548
549 if (msg->dict_len) {
550 bool line = true;
551
552 for (i = 0; i < msg->dict_len; i++) {
553 unsigned char c = log_dict(msg)[i];
554
555 if (line) {
556 user->buf[len++] = ' ';
557 line = false;
558 }
559
560 if (c == '\0') {
561 user->buf[len++] = '\n';
562 line = true;
563 continue;
564 }
565
566 if (c < ' ' || c >= 127 || c == '\\') {
567 len += sprintf(user->buf + len, "\\x%02x", c);
568 continue;
569 }
570
571 user->buf[len++] = c;
572 }
573 user->buf[len++] = '\n';
574 }
575
576 user->idx = log_next(user->idx);
577 user->seq++;
578 raw_spin_unlock_irq(&logbuf_lock);
579
580 if (len > count) {
581 ret = -EINVAL;
582 goto out;
583 }
584
585 if (copy_to_user(buf, user->buf, len)) {
586 ret = -EFAULT;
587 goto out;
588 }
589 ret = len;
590out:
591 mutex_unlock(&user->lock);
592 return ret;
593}
594
595static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
596{
597 struct devkmsg_user *user = file->private_data;
598 loff_t ret = 0;
599
600 if (!user)
601 return -EBADF;
602 if (offset)
603 return -ESPIPE;
604
605 raw_spin_lock_irq(&logbuf_lock);
606 switch (whence) {
607 case SEEK_SET:
608 /* the first record */
609 user->idx = log_first_idx;
610 user->seq = log_first_seq;
611 break;
612 case SEEK_DATA:
613 /*
614 * The first record after the last SYSLOG_ACTION_CLEAR,
615 * like issued by 'dmesg -c'. Reading /dev/kmsg itself
616 * changes no global state, and does not clear anything.
617 */
618 user->idx = clear_idx;
619 user->seq = clear_seq;
620 break;
621 case SEEK_END:
622 /* after the last record */
623 user->idx = log_next_idx;
624 user->seq = log_next_seq;
625 break;
626 default:
627 ret = -EINVAL;
628 }
629 raw_spin_unlock_irq(&logbuf_lock);
630 return ret;
631}
632
633static unsigned int devkmsg_poll(struct file *file, poll_table *wait)
634{
635 struct devkmsg_user *user = file->private_data;
636 int ret = 0;
637
638 if (!user)
639 return POLLERR|POLLNVAL;
640
641 poll_wait(file, &log_wait, wait);
642
643 raw_spin_lock_irq(&logbuf_lock);
644 if (user->seq < log_next_seq) {
645 /* return error when data has vanished underneath us */
646 if (user->seq < log_first_seq)
647 ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI;
648 else
649 ret = POLLIN|POLLRDNORM;
650 }
651 raw_spin_unlock_irq(&logbuf_lock);
652
653 return ret;
654}
655
656static int devkmsg_open(struct inode *inode, struct file *file)
657{
658 struct devkmsg_user *user;
659 int err;
660
661 /* write-only does not need any file context */
662 if ((file->f_flags & O_ACCMODE) == O_WRONLY)
663 return 0;
664
665 err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
666 SYSLOG_FROM_READER);
667 if (err)
668 return err;
669
670 user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL);
671 if (!user)
672 return -ENOMEM;
673
674 mutex_init(&user->lock);
675
676 raw_spin_lock_irq(&logbuf_lock);
677 user->idx = log_first_idx;
678 user->seq = log_first_seq;
679 raw_spin_unlock_irq(&logbuf_lock);
680
681 file->private_data = user;
682 return 0;
683}
684
685static int devkmsg_release(struct inode *inode, struct file *file)
686{
687 struct devkmsg_user *user = file->private_data;
688
689 if (!user)
690 return 0;
691
692 mutex_destroy(&user->lock);
693 kfree(user);
694 return 0;
695}
696
697const struct file_operations kmsg_fops = {
698 .open = devkmsg_open,
699 .read = devkmsg_read,
700 .aio_write = devkmsg_writev,
701 .llseek = devkmsg_llseek,
702 .poll = devkmsg_poll,
703 .release = devkmsg_release,
704};
705
706#ifdef CONFIG_KEXEC
707/*
708 * This appends the listed symbols to /proc/vmcoreinfo
709 *
710 * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
711 * obtain access to symbols that are otherwise very difficult to locate. These
712 * symbols are specifically used so that utilities can access and extract the
713 * dmesg log from a vmcore file after a crash.
714 */
715void log_buf_kexec_setup(void)
716{
717 VMCOREINFO_SYMBOL(log_buf);
718 VMCOREINFO_SYMBOL(log_buf_len);
719 VMCOREINFO_SYMBOL(log_first_idx);
720 VMCOREINFO_SYMBOL(log_next_idx);
721 /*
722 * Export struct printk_log size and field offsets. User space tools can
723 * parse it and detect any changes to structure down the line.
724 */
725 VMCOREINFO_STRUCT_SIZE(printk_log);
726 VMCOREINFO_OFFSET(printk_log, ts_nsec);
727 VMCOREINFO_OFFSET(printk_log, len);
728 VMCOREINFO_OFFSET(printk_log, text_len);
729 VMCOREINFO_OFFSET(printk_log, dict_len);
730}
731#endif
732
733/* requested log_buf_len from kernel cmdline */
734static unsigned long __initdata new_log_buf_len;
735
736/* save requested log_buf_len since it's too early to process it */
737static int __init log_buf_len_setup(char *str)
738{
739 unsigned size = memparse(str, &str);
740
741 if (size)
742 size = roundup_pow_of_two(size);
743 if (size > log_buf_len)
744 new_log_buf_len = size;
745
746 return 0;
747}
748early_param("log_buf_len", log_buf_len_setup);
749
750void __init setup_log_buf(int early)
751{
752 unsigned long flags;
753 char *new_log_buf;
754 int free;
755
756 if (!new_log_buf_len)
757 return;
758
759 if (early) {
760 unsigned long mem;
761
762 mem = memblock_alloc(new_log_buf_len, PAGE_SIZE);
763 if (!mem)
764 return;
765 new_log_buf = __va(mem);
766 } else {
767 new_log_buf = alloc_bootmem_nopanic(new_log_buf_len);
768 }
769
770 if (unlikely(!new_log_buf)) {
771 pr_err("log_buf_len: %ld bytes not available\n",
772 new_log_buf_len);
773 return;
774 }
775
776 raw_spin_lock_irqsave(&logbuf_lock, flags);
777 log_buf_len = new_log_buf_len;
778 log_buf = new_log_buf;
779 new_log_buf_len = 0;
780 free = __LOG_BUF_LEN - log_next_idx;
781 memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
782 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
783
784 pr_info("log_buf_len: %d\n", log_buf_len);
785 pr_info("early log buf free: %d(%d%%)\n",
786 free, (free * 100) / __LOG_BUF_LEN);
787}
788
789static bool __read_mostly ignore_loglevel;
790
791static int __init ignore_loglevel_setup(char *str)
792{
793 ignore_loglevel = 1;
794 printk(KERN_INFO "debug: ignoring loglevel setting.\n");
795
796 return 0;
797}
798
799early_param("ignore_loglevel", ignore_loglevel_setup);
800module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR);
801MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to"
802 "print all kernel messages to the console.");
803
804#ifdef CONFIG_BOOT_PRINTK_DELAY
805
806static int boot_delay; /* msecs delay after each printk during bootup */
807static unsigned long long loops_per_msec; /* based on boot_delay */
808
809static int __init boot_delay_setup(char *str)
810{
811 unsigned long lpj;
812
813 lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */
814 loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
815
816 get_option(&str, &boot_delay);
817 if (boot_delay > 10 * 1000)
818 boot_delay = 0;
819
820 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
821 "HZ: %d, loops_per_msec: %llu\n",
822 boot_delay, preset_lpj, lpj, HZ, loops_per_msec);
823 return 1;
824}
825__setup("boot_delay=", boot_delay_setup);
826
827static void boot_delay_msec(int level)
828{
829 unsigned long long k;
830 unsigned long timeout;
831
832 if ((boot_delay == 0 || system_state != SYSTEM_BOOTING)
833 || (level >= console_loglevel && !ignore_loglevel)) {
834 return;
835 }
836
837 k = (unsigned long long)loops_per_msec * boot_delay;
838
839 timeout = jiffies + msecs_to_jiffies(boot_delay);
840 while (k) {
841 k--;
842 cpu_relax();
843 /*
844 * use (volatile) jiffies to prevent
845 * compiler reduction; loop termination via jiffies
846 * is secondary and may or may not happen.
847 */
848 if (time_after(jiffies, timeout))
849 break;
850 touch_nmi_watchdog();
851 }
852}
853#else
854static inline void boot_delay_msec(int level)
855{
856}
857#endif
858
859#if defined(CONFIG_PRINTK_TIME)
860static bool printk_time = 1;
861#else
862static bool printk_time;
863#endif
864module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
865
866static size_t print_time(u64 ts, char *buf)
867{
868 unsigned long rem_nsec;
869
870 if (!printk_time)
871 return 0;
872
873 rem_nsec = do_div(ts, 1000000000);
874
875 if (!buf)
876 return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts);
877
878 return sprintf(buf, "[%5lu.%06lu] ",
879 (unsigned long)ts, rem_nsec / 1000);
880}
881
882static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf)
883{
884 size_t len = 0;
885 unsigned int prefix = (msg->facility << 3) | msg->level;
886
887 if (syslog) {
888 if (buf) {
889 len += sprintf(buf, "<%u>", prefix);
890 } else {
891 len += 3;
892 if (prefix > 999)
893 len += 3;
894 else if (prefix > 99)
895 len += 2;
896 else if (prefix > 9)
897 len++;
898 }
899 }
900
901 len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
902 return len;
903}
904
905static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev,
906 bool syslog, char *buf, size_t size)
907{
908 const char *text = log_text(msg);
909 size_t text_size = msg->text_len;
910 bool prefix = true;
911 bool newline = true;
912 size_t len = 0;
913
914 if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
915 prefix = false;
916
917 if (msg->flags & LOG_CONT) {
918 if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE))
919 prefix = false;
920
921 if (!(msg->flags & LOG_NEWLINE))
922 newline = false;
923 }
924
925 do {
926 const char *next = memchr(text, '\n', text_size);
927 size_t text_len;
928
929 if (next) {
930 text_len = next - text;
931 next++;
932 text_size -= next - text;
933 } else {
934 text_len = text_size;
935 }
936
937 if (buf) {
938 if (print_prefix(msg, syslog, NULL) +
939 text_len + 1 >= size - len)
940 break;
941
942 if (prefix)
943 len += print_prefix(msg, syslog, buf + len);
944 memcpy(buf + len, text, text_len);
945 len += text_len;
946 if (next || newline)
947 buf[len++] = '\n';
948 } else {
949 /* SYSLOG_ACTION_* buffer size only calculation */
950 if (prefix)
951 len += print_prefix(msg, syslog, NULL);
952 len += text_len;
953 if (next || newline)
954 len++;
955 }
956
957 prefix = true;
958 text = next;
959 } while (text);
960
961 return len;
962}
963
964static int syslog_print(char __user *buf, int size)
965{
966 char *text;
967 struct printk_log *msg;
968 int len = 0;
969
970 text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
971 if (!text)
972 return -ENOMEM;
973
974 while (size > 0) {
975 size_t n;
976 size_t skip;
977
978 raw_spin_lock_irq(&logbuf_lock);
979 if (syslog_seq < log_first_seq) {
980 /* messages are gone, move to first one */
981 syslog_seq = log_first_seq;
982 syslog_idx = log_first_idx;
983 syslog_prev = 0;
984 syslog_partial = 0;
985 }
986 if (syslog_seq == log_next_seq) {
987 raw_spin_unlock_irq(&logbuf_lock);
988 break;
989 }
990
991 skip = syslog_partial;
992 msg = log_from_idx(syslog_idx);
993 n = msg_print_text(msg, syslog_prev, true, text,
994 LOG_LINE_MAX + PREFIX_MAX);
995 if (n - syslog_partial <= size) {
996 /* message fits into buffer, move forward */
997 syslog_idx = log_next(syslog_idx);
998 syslog_seq++;
999 syslog_prev = msg->flags;
1000 n -= syslog_partial;
1001 syslog_partial = 0;
1002 } else if (!len){
1003 /* partial read(), remember position */
1004 n = size;
1005 syslog_partial += n;
1006 } else
1007 n = 0;
1008 raw_spin_unlock_irq(&logbuf_lock);
1009
1010 if (!n)
1011 break;
1012
1013 if (copy_to_user(buf, text + skip, n)) {
1014 if (!len)
1015 len = -EFAULT;
1016 break;
1017 }
1018
1019 len += n;
1020 size -= n;
1021 buf += n;
1022 }
1023
1024 kfree(text);
1025 return len;
1026}
1027
1028static int syslog_print_all(char __user *buf, int size, bool clear)
1029{
1030 char *text;
1031 int len = 0;
1032
1033 text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
1034 if (!text)
1035 return -ENOMEM;
1036
1037 raw_spin_lock_irq(&logbuf_lock);
1038 if (buf) {
1039 u64 next_seq;
1040 u64 seq;
1041 u32 idx;
1042 enum log_flags prev;
1043
1044 if (clear_seq < log_first_seq) {
1045 /* messages are gone, move to first available one */
1046 clear_seq = log_first_seq;
1047 clear_idx = log_first_idx;
1048 }
1049
1050 /*
1051 * Find first record that fits, including all following records,
1052 * into the user-provided buffer for this dump.
1053 */
1054 seq = clear_seq;
1055 idx = clear_idx;
1056 prev = 0;
1057 while (seq < log_next_seq) {
1058 struct printk_log *msg = log_from_idx(idx);
1059
1060 len += msg_print_text(msg, prev, true, NULL, 0);
1061 prev = msg->flags;
1062 idx = log_next(idx);
1063 seq++;
1064 }
1065
1066 /* move first record forward until length fits into the buffer */
1067 seq = clear_seq;
1068 idx = clear_idx;
1069 prev = 0;
1070 while (len > size && seq < log_next_seq) {
1071 struct printk_log *msg = log_from_idx(idx);
1072
1073 len -= msg_print_text(msg, prev, true, NULL, 0);
1074 prev = msg->flags;
1075 idx = log_next(idx);
1076 seq++;
1077 }
1078
1079 /* last message fitting into this dump */
1080 next_seq = log_next_seq;
1081
1082 len = 0;
1083 prev = 0;
1084 while (len >= 0 && seq < next_seq) {
1085 struct printk_log *msg = log_from_idx(idx);
1086 int textlen;
1087
1088 textlen = msg_print_text(msg, prev, true, text,
1089 LOG_LINE_MAX + PREFIX_MAX);
1090 if (textlen < 0) {
1091 len = textlen;
1092 break;
1093 }
1094 idx = log_next(idx);
1095 seq++;
1096 prev = msg->flags;
1097
1098 raw_spin_unlock_irq(&logbuf_lock);
1099 if (copy_to_user(buf + len, text, textlen))
1100 len = -EFAULT;
1101 else
1102 len += textlen;
1103 raw_spin_lock_irq(&logbuf_lock);
1104
1105 if (seq < log_first_seq) {
1106 /* messages are gone, move to next one */
1107 seq = log_first_seq;
1108 idx = log_first_idx;
1109 prev = 0;
1110 }
1111 }
1112 }
1113
1114 if (clear) {
1115 clear_seq = log_next_seq;
1116 clear_idx = log_next_idx;
1117 }
1118 raw_spin_unlock_irq(&logbuf_lock);
1119
1120 kfree(text);
1121 return len;
1122}
1123
1124int do_syslog(int type, char __user *buf, int len, bool from_file)
1125{
1126 bool clear = false;
1127 static int saved_console_loglevel = -1;
1128 int error;
1129
1130 error = check_syslog_permissions(type, from_file);
1131 if (error)
1132 goto out;
1133
1134 error = security_syslog(type);
1135 if (error)
1136 return error;
1137
1138 switch (type) {
1139 case SYSLOG_ACTION_CLOSE: /* Close log */
1140 break;
1141 case SYSLOG_ACTION_OPEN: /* Open log */
1142 break;
1143 case SYSLOG_ACTION_READ: /* Read from log */
1144 error = -EINVAL;
1145 if (!buf || len < 0)
1146 goto out;
1147 error = 0;
1148 if (!len)
1149 goto out;
1150 if (!access_ok(VERIFY_WRITE, buf, len)) {
1151 error = -EFAULT;
1152 goto out;
1153 }
1154 error = wait_event_interruptible(log_wait,
1155 syslog_seq != log_next_seq);
1156 if (error)
1157 goto out;
1158 error = syslog_print(buf, len);
1159 break;
1160 /* Read/clear last kernel messages */
1161 case SYSLOG_ACTION_READ_CLEAR:
1162 clear = true;
1163 /* FALL THRU */
1164 /* Read last kernel messages */
1165 case SYSLOG_ACTION_READ_ALL:
1166 error = -EINVAL;
1167 if (!buf || len < 0)
1168 goto out;
1169 error = 0;
1170 if (!len)
1171 goto out;
1172 if (!access_ok(VERIFY_WRITE, buf, len)) {
1173 error = -EFAULT;
1174 goto out;
1175 }
1176 error = syslog_print_all(buf, len, clear);
1177 break;
1178 /* Clear ring buffer */
1179 case SYSLOG_ACTION_CLEAR:
1180 syslog_print_all(NULL, 0, true);
1181 break;
1182 /* Disable logging to console */
1183 case SYSLOG_ACTION_CONSOLE_OFF:
1184 if (saved_console_loglevel == -1)
1185 saved_console_loglevel = console_loglevel;
1186 console_loglevel = minimum_console_loglevel;
1187 break;
1188 /* Enable logging to console */
1189 case SYSLOG_ACTION_CONSOLE_ON:
1190 if (saved_console_loglevel != -1) {
1191 console_loglevel = saved_console_loglevel;
1192 saved_console_loglevel = -1;
1193 }
1194 break;
1195 /* Set level of messages printed to console */
1196 case SYSLOG_ACTION_CONSOLE_LEVEL:
1197 error = -EINVAL;
1198 if (len < 1 || len > 8)
1199 goto out;
1200 if (len < minimum_console_loglevel)
1201 len = minimum_console_loglevel;
1202 console_loglevel = len;
1203 /* Implicitly re-enable logging to console */
1204 saved_console_loglevel = -1;
1205 error = 0;
1206 break;
1207 /* Number of chars in the log buffer */
1208 case SYSLOG_ACTION_SIZE_UNREAD:
1209 raw_spin_lock_irq(&logbuf_lock);
1210 if (syslog_seq < log_first_seq) {
1211 /* messages are gone, move to first one */
1212 syslog_seq = log_first_seq;
1213 syslog_idx = log_first_idx;
1214 syslog_prev = 0;
1215 syslog_partial = 0;
1216 }
1217 if (from_file) {
1218 /*
1219 * Short-cut for poll(/"proc/kmsg") which simply checks
1220 * for pending data, not the size; return the count of
1221 * records, not the length.
1222 */
1223 error = log_next_idx - syslog_idx;
1224 } else {
1225 u64 seq = syslog_seq;
1226 u32 idx = syslog_idx;
1227 enum log_flags prev = syslog_prev;
1228
1229 error = 0;
1230 while (seq < log_next_seq) {
1231 struct printk_log *msg = log_from_idx(idx);
1232
1233 error += msg_print_text(msg, prev, true, NULL, 0);
1234 idx = log_next(idx);
1235 seq++;
1236 prev = msg->flags;
1237 }
1238 error -= syslog_partial;
1239 }
1240 raw_spin_unlock_irq(&logbuf_lock);
1241 break;
1242 /* Size of the log buffer */
1243 case SYSLOG_ACTION_SIZE_BUFFER:
1244 error = log_buf_len;
1245 break;
1246 default:
1247 error = -EINVAL;
1248 break;
1249 }
1250out:
1251 return error;
1252}
1253
1254SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
1255{
1256 return do_syslog(type, buf, len, SYSLOG_FROM_READER);
1257}
1258
1259/*
1260 * Call the console drivers, asking them to write out
1261 * log_buf[start] to log_buf[end - 1].
1262 * The console_lock must be held.
1263 */
1264static void call_console_drivers(int level, const char *text, size_t len)
1265{
1266 struct console *con;
1267
1268 trace_console(text, len);
1269
1270 if (level >= console_loglevel && !ignore_loglevel)
1271 return;
1272 if (!console_drivers)
1273 return;
1274
1275 for_each_console(con) {
1276 if (exclusive_console && con != exclusive_console)
1277 continue;
1278 if (!(con->flags & CON_ENABLED))
1279 continue;
1280 if (!con->write)
1281 continue;
1282 if (!cpu_online(smp_processor_id()) &&
1283 !(con->flags & CON_ANYTIME))
1284 continue;
1285 con->write(con, text, len);
1286 }
1287}
1288
1289/*
1290 * Zap console related locks when oopsing. Only zap at most once
1291 * every 10 seconds, to leave time for slow consoles to print a
1292 * full oops.
1293 */
1294static void zap_locks(void)
1295{
1296 static unsigned long oops_timestamp;
1297
1298 if (time_after_eq(jiffies, oops_timestamp) &&
1299 !time_after(jiffies, oops_timestamp + 30 * HZ))
1300 return;
1301
1302 oops_timestamp = jiffies;
1303
1304 debug_locks_off();
1305 /* If a crash is occurring, make sure we can't deadlock */
1306 raw_spin_lock_init(&logbuf_lock);
1307 /* And make sure that we print immediately */
1308 sema_init(&console_sem, 1);
1309}
1310
1311/* Check if we have any console registered that can be called early in boot. */
1312static int have_callable_console(void)
1313{
1314 struct console *con;
1315
1316 for_each_console(con)
1317 if (con->flags & CON_ANYTIME)
1318 return 1;
1319
1320 return 0;
1321}
1322
1323/*
1324 * Can we actually use the console at this time on this cpu?
1325 *
1326 * Console drivers may assume that per-cpu resources have
1327 * been allocated. So unless they're explicitly marked as
1328 * being able to cope (CON_ANYTIME) don't call them until
1329 * this CPU is officially up.
1330 */
1331static inline int can_use_console(unsigned int cpu)
1332{
1333 return cpu_online(cpu) || have_callable_console();
1334}
1335
1336/*
1337 * Try to get console ownership to actually show the kernel
1338 * messages from a 'printk'. Return true (and with the
1339 * console_lock held, and 'console_locked' set) if it
1340 * is successful, false otherwise.
1341 *
1342 * This gets called with the 'logbuf_lock' spinlock held and
1343 * interrupts disabled. It should return with 'lockbuf_lock'
1344 * released but interrupts still disabled.
1345 */
1346static int console_trylock_for_printk(unsigned int cpu)
1347 __releases(&logbuf_lock)
1348{
1349 int retval = 0, wake = 0;
1350
1351 if (console_trylock()) {
1352 retval = 1;
1353
1354 /*
1355 * If we can't use the console, we need to release
1356 * the console semaphore by hand to avoid flushing
1357 * the buffer. We need to hold the console semaphore
1358 * in order to do this test safely.
1359 */
1360 if (!can_use_console(cpu)) {
1361 console_locked = 0;
1362 wake = 1;
1363 retval = 0;
1364 }
1365 }
1366 logbuf_cpu = UINT_MAX;
1367 raw_spin_unlock(&logbuf_lock);
1368 if (wake)
1369 up(&console_sem);
1370 return retval;
1371}
1372
1373int printk_delay_msec __read_mostly;
1374
1375static inline void printk_delay(void)
1376{
1377 if (unlikely(printk_delay_msec)) {
1378 int m = printk_delay_msec;
1379
1380 while (m--) {
1381 mdelay(1);
1382 touch_nmi_watchdog();
1383 }
1384 }
1385}
1386
1387/*
1388 * Continuation lines are buffered, and not committed to the record buffer
1389 * until the line is complete, or a race forces it. The line fragments
1390 * though, are printed immediately to the consoles to ensure everything has
1391 * reached the console in case of a kernel crash.
1392 */
1393static struct cont {
1394 char buf[LOG_LINE_MAX];
1395 size_t len; /* length == 0 means unused buffer */
1396 size_t cons; /* bytes written to console */
1397 struct task_struct *owner; /* task of first print*/
1398 u64 ts_nsec; /* time of first print */
1399 u8 level; /* log level of first message */
1400 u8 facility; /* log level of first message */
1401 enum log_flags flags; /* prefix, newline flags */
1402 bool flushed:1; /* buffer sealed and committed */
1403} cont;
1404
1405static void cont_flush(enum log_flags flags)
1406{
1407 if (cont.flushed)
1408 return;
1409 if (cont.len == 0)
1410 return;
1411
1412 if (cont.cons) {
1413 /*
1414 * If a fragment of this line was directly flushed to the
1415 * console; wait for the console to pick up the rest of the
1416 * line. LOG_NOCONS suppresses a duplicated output.
1417 */
1418 log_store(cont.facility, cont.level, flags | LOG_NOCONS,
1419 cont.ts_nsec, NULL, 0, cont.buf, cont.len);
1420 cont.flags = flags;
1421 cont.flushed = true;
1422 } else {
1423 /*
1424 * If no fragment of this line ever reached the console,
1425 * just submit it to the store and free the buffer.
1426 */
1427 log_store(cont.facility, cont.level, flags, 0,
1428 NULL, 0, cont.buf, cont.len);
1429 cont.len = 0;
1430 }
1431}
1432
1433static bool cont_add(int facility, int level, const char *text, size_t len)
1434{
1435 if (cont.len && cont.flushed)
1436 return false;
1437
1438 if (cont.len + len > sizeof(cont.buf)) {
1439 /* the line gets too long, split it up in separate records */
1440 cont_flush(LOG_CONT);
1441 return false;
1442 }
1443
1444 if (!cont.len) {
1445 cont.facility = facility;
1446 cont.level = level;
1447 cont.owner = current;
1448 cont.ts_nsec = local_clock();
1449 cont.flags = 0;
1450 cont.cons = 0;
1451 cont.flushed = false;
1452 }
1453
1454 memcpy(cont.buf + cont.len, text, len);
1455 cont.len += len;
1456
1457 if (cont.len > (sizeof(cont.buf) * 80) / 100)
1458 cont_flush(LOG_CONT);
1459
1460 return true;
1461}
1462
1463static size_t cont_print_text(char *text, size_t size)
1464{
1465 size_t textlen = 0;
1466 size_t len;
1467
1468 if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) {
1469 textlen += print_time(cont.ts_nsec, text);
1470 size -= textlen;
1471 }
1472
1473 len = cont.len - cont.cons;
1474 if (len > 0) {
1475 if (len+1 > size)
1476 len = size-1;
1477 memcpy(text + textlen, cont.buf + cont.cons, len);
1478 textlen += len;
1479 cont.cons = cont.len;
1480 }
1481
1482 if (cont.flushed) {
1483 if (cont.flags & LOG_NEWLINE)
1484 text[textlen++] = '\n';
1485 /* got everything, release buffer */
1486 cont.len = 0;
1487 }
1488 return textlen;
1489}
1490
1491asmlinkage int vprintk_emit(int facility, int level,
1492 const char *dict, size_t dictlen,
1493 const char *fmt, va_list args)
1494{
1495 static int recursion_bug;
1496 static char textbuf[LOG_LINE_MAX];
1497 char *text = textbuf;
1498 size_t text_len;
1499 enum log_flags lflags = 0;
1500 unsigned long flags;
1501 int this_cpu;
1502 int printed_len = 0;
1503
1504 boot_delay_msec(level);
1505 printk_delay();
1506
1507 /* This stops the holder of console_sem just where we want him */
1508 local_irq_save(flags);
1509 this_cpu = smp_processor_id();
1510
1511 /*
1512 * Ouch, printk recursed into itself!
1513 */
1514 if (unlikely(logbuf_cpu == this_cpu)) {
1515 /*
1516 * If a crash is occurring during printk() on this CPU,
1517 * then try to get the crash message out but make sure
1518 * we can't deadlock. Otherwise just return to avoid the
1519 * recursion and return - but flag the recursion so that
1520 * it can be printed at the next appropriate moment:
1521 */
1522 if (!oops_in_progress && !lockdep_recursing(current)) {
1523 recursion_bug = 1;
1524 goto out_restore_irqs;
1525 }
1526 zap_locks();
1527 }
1528
1529 lockdep_off();
1530 raw_spin_lock(&logbuf_lock);
1531 logbuf_cpu = this_cpu;
1532
1533 if (recursion_bug) {
1534 static const char recursion_msg[] =
1535 "BUG: recent printk recursion!";
1536
1537 recursion_bug = 0;
1538 printed_len += strlen(recursion_msg);
1539 /* emit KERN_CRIT message */
1540 log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
1541 NULL, 0, recursion_msg, printed_len);
1542 }
1543
1544 /*
1545 * The printf needs to come first; we need the syslog
1546 * prefix which might be passed-in as a parameter.
1547 */
1548 text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
1549
1550 /* mark and strip a trailing newline */
1551 if (text_len && text[text_len-1] == '\n') {
1552 text_len--;
1553 lflags |= LOG_NEWLINE;
1554 }
1555
1556 /* strip kernel syslog prefix and extract log level or control flags */
1557 if (facility == 0) {
1558 int kern_level = printk_get_level(text);
1559
1560 if (kern_level) {
1561 const char *end_of_header = printk_skip_level(text);
1562 switch (kern_level) {
1563 case '0' ... '7':
1564 if (level == -1)
1565 level = kern_level - '0';
1566 case 'd': /* KERN_DEFAULT */
1567 lflags |= LOG_PREFIX;
1568 case 'c': /* KERN_CONT */
1569 break;
1570 }
1571 text_len -= end_of_header - text;
1572 text = (char *)end_of_header;
1573 }
1574 }
1575
1576 if (level == -1)
1577 level = default_message_loglevel;
1578
1579 if (dict)
1580 lflags |= LOG_PREFIX|LOG_NEWLINE;
1581
1582 if (!(lflags & LOG_NEWLINE)) {
1583 /*
1584 * Flush the conflicting buffer. An earlier newline was missing,
1585 * or another task also prints continuation lines.
1586 */
1587 if (cont.len && (lflags & LOG_PREFIX || cont.owner != current))
1588 cont_flush(LOG_NEWLINE);
1589
1590 /* buffer line if possible, otherwise store it right away */
1591 if (!cont_add(facility, level, text, text_len))
1592 log_store(facility, level, lflags | LOG_CONT, 0,
1593 dict, dictlen, text, text_len);
1594 } else {
1595 bool stored = false;
1596
1597 /*
1598 * If an earlier newline was missing and it was the same task,
1599 * either merge it with the current buffer and flush, or if
1600 * there was a race with interrupts (prefix == true) then just
1601 * flush it out and store this line separately.
1602 */
1603 if (cont.len && cont.owner == current) {
1604 if (!(lflags & LOG_PREFIX))
1605 stored = cont_add(facility, level, text, text_len);
1606 cont_flush(LOG_NEWLINE);
1607 }
1608
1609 if (!stored)
1610 log_store(facility, level, lflags, 0,
1611 dict, dictlen, text, text_len);
1612 }
1613 printed_len += text_len;
1614
1615 /*
1616 * Try to acquire and then immediately release the console semaphore.
1617 * The release will print out buffers and wake up /dev/kmsg and syslog()
1618 * users.
1619 *
1620 * The console_trylock_for_printk() function will release 'logbuf_lock'
1621 * regardless of whether it actually gets the console semaphore or not.
1622 */
1623 if (console_trylock_for_printk(this_cpu))
1624 console_unlock();
1625
1626 lockdep_on();
1627out_restore_irqs:
1628 local_irq_restore(flags);
1629
1630 return printed_len;
1631}
1632EXPORT_SYMBOL(vprintk_emit);
1633
1634asmlinkage int vprintk(const char *fmt, va_list args)
1635{
1636 return vprintk_emit(0, -1, NULL, 0, fmt, args);
1637}
1638EXPORT_SYMBOL(vprintk);
1639
1640asmlinkage int printk_emit(int facility, int level,
1641 const char *dict, size_t dictlen,
1642 const char *fmt, ...)
1643{
1644 va_list args;
1645 int r;
1646
1647 va_start(args, fmt);
1648 r = vprintk_emit(facility, level, dict, dictlen, fmt, args);
1649 va_end(args);
1650
1651 return r;
1652}
1653EXPORT_SYMBOL(printk_emit);
1654
1655/**
1656 * printk - print a kernel message
1657 * @fmt: format string
1658 *
1659 * This is printk(). It can be called from any context. We want it to work.
1660 *
1661 * We try to grab the console_lock. If we succeed, it's easy - we log the
1662 * output and call the console drivers. If we fail to get the semaphore, we
1663 * place the output into the log buffer and return. The current holder of
1664 * the console_sem will notice the new output in console_unlock(); and will
1665 * send it to the consoles before releasing the lock.
1666 *
1667 * One effect of this deferred printing is that code which calls printk() and
1668 * then changes console_loglevel may break. This is because console_loglevel
1669 * is inspected when the actual printing occurs.
1670 *
1671 * See also:
1672 * printf(3)
1673 *
1674 * See the vsnprintf() documentation for format string extensions over C99.
1675 */
1676asmlinkage int printk(const char *fmt, ...)
1677{
1678 va_list args;
1679 int r;
1680
1681#ifdef CONFIG_KGDB_KDB
1682 if (unlikely(kdb_trap_printk)) {
1683 va_start(args, fmt);
1684 r = vkdb_printf(fmt, args);
1685 va_end(args);
1686 return r;
1687 }
1688#endif
1689 va_start(args, fmt);
1690 r = vprintk_emit(0, -1, NULL, 0, fmt, args);
1691 va_end(args);
1692
1693 return r;
1694}
1695EXPORT_SYMBOL(printk);
1696
1697#else /* CONFIG_PRINTK */
1698
1699#define LOG_LINE_MAX 0
1700#define PREFIX_MAX 0
1701#define LOG_LINE_MAX 0
1702static u64 syslog_seq;
1703static u32 syslog_idx;
1704static u64 console_seq;
1705static u32 console_idx;
1706static enum log_flags syslog_prev;
1707static u64 log_first_seq;
1708static u32 log_first_idx;
1709static u64 log_next_seq;
1710static enum log_flags console_prev;
1711static struct cont {
1712 size_t len;
1713 size_t cons;
1714 u8 level;
1715 bool flushed:1;
1716} cont;
1717static struct printk_log *log_from_idx(u32 idx) { return NULL; }
1718static u32 log_next(u32 idx) { return 0; }
1719static void call_console_drivers(int level, const char *text, size_t len) {}
1720static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev,
1721 bool syslog, char *buf, size_t size) { return 0; }
1722static size_t cont_print_text(char *text, size_t size) { return 0; }
1723
1724#endif /* CONFIG_PRINTK */
1725
1726#ifdef CONFIG_EARLY_PRINTK
1727struct console *early_console;
1728
1729void early_vprintk(const char *fmt, va_list ap)
1730{
1731 if (early_console) {
1732 char buf[512];
1733 int n = vscnprintf(buf, sizeof(buf), fmt, ap);
1734
1735 early_console->write(early_console, buf, n);
1736 }
1737}
1738
1739asmlinkage void early_printk(const char *fmt, ...)
1740{
1741 va_list ap;
1742
1743 va_start(ap, fmt);
1744 early_vprintk(fmt, ap);
1745 va_end(ap);
1746}
1747#endif
1748
1749static int __add_preferred_console(char *name, int idx, char *options,
1750 char *brl_options)
1751{
1752 struct console_cmdline *c;
1753 int i;
1754
1755 /*
1756 * See if this tty is not yet registered, and
1757 * if we have a slot free.
1758 */
1759 for (i = 0, c = console_cmdline;
1760 i < MAX_CMDLINECONSOLES && c->name[0];
1761 i++, c++) {
1762 if (strcmp(c->name, name) == 0 && c->index == idx) {
1763 if (!brl_options)
1764 selected_console = i;
1765 return 0;
1766 }
1767 }
1768 if (i == MAX_CMDLINECONSOLES)
1769 return -E2BIG;
1770 if (!brl_options)
1771 selected_console = i;
1772 strlcpy(c->name, name, sizeof(c->name));
1773 c->options = options;
1774 braille_set_options(c, brl_options);
1775
1776 c->index = idx;
1777 return 0;
1778}
1779/*
1780 * Set up a list of consoles. Called from init/main.c
1781 */
1782static int __init console_setup(char *str)
1783{
1784 char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
1785 char *s, *options, *brl_options = NULL;
1786 int idx;
1787
1788 if (_braille_console_setup(&str, &brl_options))
1789 return 1;
1790
1791 /*
1792 * Decode str into name, index, options.
1793 */
1794 if (str[0] >= '0' && str[0] <= '9') {
1795 strcpy(buf, "ttyS");
1796 strncpy(buf + 4, str, sizeof(buf) - 5);
1797 } else {
1798 strncpy(buf, str, sizeof(buf) - 1);
1799 }
1800 buf[sizeof(buf) - 1] = 0;
1801 if ((options = strchr(str, ',')) != NULL)
1802 *(options++) = 0;
1803#ifdef __sparc__
1804 if (!strcmp(str, "ttya"))
1805 strcpy(buf, "ttyS0");
1806 if (!strcmp(str, "ttyb"))
1807 strcpy(buf, "ttyS1");
1808#endif
1809 for (s = buf; *s; s++)
1810 if ((*s >= '0' && *s <= '9') || *s == ',')
1811 break;
1812 idx = simple_strtoul(s, NULL, 10);
1813 *s = 0;
1814
1815 __add_preferred_console(buf, idx, options, brl_options);
1816 console_set_on_cmdline = 1;
1817 return 1;
1818}
1819__setup("console=", console_setup);
1820
1821/**
1822 * add_preferred_console - add a device to the list of preferred consoles.
1823 * @name: device name
1824 * @idx: device index
1825 * @options: options for this console
1826 *
1827 * The last preferred console added will be used for kernel messages
1828 * and stdin/out/err for init. Normally this is used by console_setup
1829 * above to handle user-supplied console arguments; however it can also
1830 * be used by arch-specific code either to override the user or more
1831 * commonly to provide a default console (ie from PROM variables) when
1832 * the user has not supplied one.
1833 */
1834int add_preferred_console(char *name, int idx, char *options)
1835{
1836 return __add_preferred_console(name, idx, options, NULL);
1837}
1838
1839int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
1840{
1841 struct console_cmdline *c;
1842 int i;
1843
1844 for (i = 0, c = console_cmdline;
1845 i < MAX_CMDLINECONSOLES && c->name[0];
1846 i++, c++)
1847 if (strcmp(c->name, name) == 0 && c->index == idx) {
1848 strlcpy(c->name, name_new, sizeof(c->name));
1849 c->name[sizeof(c->name) - 1] = 0;
1850 c->options = options;
1851 c->index = idx_new;
1852 return i;
1853 }
1854 /* not found */
1855 return -1;
1856}
1857
1858bool console_suspend_enabled = 1;
1859EXPORT_SYMBOL(console_suspend_enabled);
1860
1861static int __init console_suspend_disable(char *str)
1862{
1863 console_suspend_enabled = 0;
1864 return 1;
1865}
1866__setup("no_console_suspend", console_suspend_disable);
1867module_param_named(console_suspend, console_suspend_enabled,
1868 bool, S_IRUGO | S_IWUSR);
1869MODULE_PARM_DESC(console_suspend, "suspend console during suspend"
1870 " and hibernate operations");
1871
1872/**
1873 * suspend_console - suspend the console subsystem
1874 *
1875 * This disables printk() while we go into suspend states
1876 */
1877void suspend_console(void)
1878{
1879 if (!console_suspend_enabled)
1880 return;
1881 printk("Suspending console(s) (use no_console_suspend to debug)\n");
1882 console_lock();
1883 console_suspended = 1;
1884 up(&console_sem);
1885}
1886
1887void resume_console(void)
1888{
1889 if (!console_suspend_enabled)
1890 return;
1891 down(&console_sem);
1892 console_suspended = 0;
1893 console_unlock();
1894}
1895
1896/**
1897 * console_cpu_notify - print deferred console messages after CPU hotplug
1898 * @self: notifier struct
1899 * @action: CPU hotplug event
1900 * @hcpu: unused
1901 *
1902 * If printk() is called from a CPU that is not online yet, the messages
1903 * will be spooled but will not show up on the console. This function is
1904 * called when a new CPU comes online (or fails to come up), and ensures
1905 * that any such output gets printed.
1906 */
1907static int console_cpu_notify(struct notifier_block *self,
1908 unsigned long action, void *hcpu)
1909{
1910 switch (action) {
1911 case CPU_ONLINE:
1912 case CPU_DEAD:
1913 case CPU_DOWN_FAILED:
1914 case CPU_UP_CANCELED:
1915 console_lock();
1916 console_unlock();
1917 }
1918 return NOTIFY_OK;
1919}
1920
1921/**
1922 * console_lock - lock the console system for exclusive use.
1923 *
1924 * Acquires a lock which guarantees that the caller has
1925 * exclusive access to the console system and the console_drivers list.
1926 *
1927 * Can sleep, returns nothing.
1928 */
1929void console_lock(void)
1930{
1931 might_sleep();
1932
1933 down(&console_sem);
1934 if (console_suspended)
1935 return;
1936 console_locked = 1;
1937 console_may_schedule = 1;
1938 mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
1939}
1940EXPORT_SYMBOL(console_lock);
1941
1942/**
1943 * console_trylock - try to lock the console system for exclusive use.
1944 *
1945 * Tried to acquire a lock which guarantees that the caller has
1946 * exclusive access to the console system and the console_drivers list.
1947 *
1948 * returns 1 on success, and 0 on failure to acquire the lock.
1949 */
1950int console_trylock(void)
1951{
1952 if (down_trylock(&console_sem))
1953 return 0;
1954 if (console_suspended) {
1955 up(&console_sem);
1956 return 0;
1957 }
1958 console_locked = 1;
1959 console_may_schedule = 0;
1960 mutex_acquire(&console_lock_dep_map, 0, 1, _RET_IP_);
1961 return 1;
1962}
1963EXPORT_SYMBOL(console_trylock);
1964
1965int is_console_locked(void)
1966{
1967 return console_locked;
1968}
1969
1970static void console_cont_flush(char *text, size_t size)
1971{
1972 unsigned long flags;
1973 size_t len;
1974
1975 raw_spin_lock_irqsave(&logbuf_lock, flags);
1976
1977 if (!cont.len)
1978 goto out;
1979
1980 /*
1981 * We still queue earlier records, likely because the console was
1982 * busy. The earlier ones need to be printed before this one, we
1983 * did not flush any fragment so far, so just let it queue up.
1984 */
1985 if (console_seq < log_next_seq && !cont.cons)
1986 goto out;
1987
1988 len = cont_print_text(text, size);
1989 raw_spin_unlock(&logbuf_lock);
1990 stop_critical_timings();
1991 call_console_drivers(cont.level, text, len);
1992 start_critical_timings();
1993 local_irq_restore(flags);
1994 return;
1995out:
1996 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
1997}
1998
1999/**
2000 * console_unlock - unlock the console system
2001 *
2002 * Releases the console_lock which the caller holds on the console system
2003 * and the console driver list.
2004 *
2005 * While the console_lock was held, console output may have been buffered
2006 * by printk(). If this is the case, console_unlock(); emits
2007 * the output prior to releasing the lock.
2008 *
2009 * If there is output waiting, we wake /dev/kmsg and syslog() users.
2010 *
2011 * console_unlock(); may be called from any context.
2012 */
2013void console_unlock(void)
2014{
2015 static char text[LOG_LINE_MAX + PREFIX_MAX];
2016 static u64 seen_seq;
2017 unsigned long flags;
2018 bool wake_klogd = false;
2019 bool retry;
2020
2021 if (console_suspended) {
2022 up(&console_sem);
2023 return;
2024 }
2025
2026 console_may_schedule = 0;
2027
2028 /* flush buffered message fragment immediately to console */
2029 console_cont_flush(text, sizeof(text));
2030again:
2031 for (;;) {
2032 struct printk_log *msg;
2033 size_t len;
2034 int level;
2035
2036 raw_spin_lock_irqsave(&logbuf_lock, flags);
2037 if (seen_seq != log_next_seq) {
2038 wake_klogd = true;
2039 seen_seq = log_next_seq;
2040 }
2041
2042 if (console_seq < log_first_seq) {
2043 /* messages are gone, move to first one */
2044 console_seq = log_first_seq;
2045 console_idx = log_first_idx;
2046 console_prev = 0;
2047 }
2048skip:
2049 if (console_seq == log_next_seq)
2050 break;
2051
2052 msg = log_from_idx(console_idx);
2053 if (msg->flags & LOG_NOCONS) {
2054 /*
2055 * Skip record we have buffered and already printed
2056 * directly to the console when we received it.
2057 */
2058 console_idx = log_next(console_idx);
2059 console_seq++;
2060 /*
2061 * We will get here again when we register a new
2062 * CON_PRINTBUFFER console. Clear the flag so we
2063 * will properly dump everything later.
2064 */
2065 msg->flags &= ~LOG_NOCONS;
2066 console_prev = msg->flags;
2067 goto skip;
2068 }
2069
2070 level = msg->level;
2071 len = msg_print_text(msg, console_prev, false,
2072 text, sizeof(text));
2073 console_idx = log_next(console_idx);
2074 console_seq++;
2075 console_prev = msg->flags;
2076 raw_spin_unlock(&logbuf_lock);
2077
2078 stop_critical_timings(); /* don't trace print latency */
2079 call_console_drivers(level, text, len);
2080 start_critical_timings();
2081 local_irq_restore(flags);
2082 }
2083 console_locked = 0;
2084 mutex_release(&console_lock_dep_map, 1, _RET_IP_);
2085
2086 /* Release the exclusive_console once it is used */
2087 if (unlikely(exclusive_console))
2088 exclusive_console = NULL;
2089
2090 raw_spin_unlock(&logbuf_lock);
2091
2092 up(&console_sem);
2093
2094 /*
2095 * Someone could have filled up the buffer again, so re-check if there's
2096 * something to flush. In case we cannot trylock the console_sem again,
2097 * there's a new owner and the console_unlock() from them will do the
2098 * flush, no worries.
2099 */
2100 raw_spin_lock(&logbuf_lock);
2101 retry = console_seq != log_next_seq;
2102 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2103
2104 if (retry && console_trylock())
2105 goto again;
2106
2107 if (wake_klogd)
2108 wake_up_klogd();
2109}
2110EXPORT_SYMBOL(console_unlock);
2111
2112/**
2113 * console_conditional_schedule - yield the CPU if required
2114 *
2115 * If the console code is currently allowed to sleep, and
2116 * if this CPU should yield the CPU to another task, do
2117 * so here.
2118 *
2119 * Must be called within console_lock();.
2120 */
2121void __sched console_conditional_schedule(void)
2122{
2123 if (console_may_schedule)
2124 cond_resched();
2125}
2126EXPORT_SYMBOL(console_conditional_schedule);
2127
2128void console_unblank(void)
2129{
2130 struct console *c;
2131
2132 /*
2133 * console_unblank can no longer be called in interrupt context unless
2134 * oops_in_progress is set to 1..
2135 */
2136 if (oops_in_progress) {
2137 if (down_trylock(&console_sem) != 0)
2138 return;
2139 } else
2140 console_lock();
2141
2142 console_locked = 1;
2143 console_may_schedule = 0;
2144 for_each_console(c)
2145 if ((c->flags & CON_ENABLED) && c->unblank)
2146 c->unblank();
2147 console_unlock();
2148}
2149
2150/*
2151 * Return the console tty driver structure and its associated index
2152 */
2153struct tty_driver *console_device(int *index)
2154{
2155 struct console *c;
2156 struct tty_driver *driver = NULL;
2157
2158 console_lock();
2159 for_each_console(c) {
2160 if (!c->device)
2161 continue;
2162 driver = c->device(c, index);
2163 if (driver)
2164 break;
2165 }
2166 console_unlock();
2167 return driver;
2168}
2169
2170/*
2171 * Prevent further output on the passed console device so that (for example)
2172 * serial drivers can disable console output before suspending a port, and can
2173 * re-enable output afterwards.
2174 */
2175void console_stop(struct console *console)
2176{
2177 console_lock();
2178 console->flags &= ~CON_ENABLED;
2179 console_unlock();
2180}
2181EXPORT_SYMBOL(console_stop);
2182
2183void console_start(struct console *console)
2184{
2185 console_lock();
2186 console->flags |= CON_ENABLED;
2187 console_unlock();
2188}
2189EXPORT_SYMBOL(console_start);
2190
2191static int __read_mostly keep_bootcon;
2192
2193static int __init keep_bootcon_setup(char *str)
2194{
2195 keep_bootcon = 1;
2196 printk(KERN_INFO "debug: skip boot console de-registration.\n");
2197
2198 return 0;
2199}
2200
2201early_param("keep_bootcon", keep_bootcon_setup);
2202
2203/*
2204 * The console driver calls this routine during kernel initialization
2205 * to register the console printing procedure with printk() and to
2206 * print any messages that were printed by the kernel before the
2207 * console driver was initialized.
2208 *
2209 * This can happen pretty early during the boot process (because of
2210 * early_printk) - sometimes before setup_arch() completes - be careful
2211 * of what kernel features are used - they may not be initialised yet.
2212 *
2213 * There are two types of consoles - bootconsoles (early_printk) and
2214 * "real" consoles (everything which is not a bootconsole) which are
2215 * handled differently.
2216 * - Any number of bootconsoles can be registered at any time.
2217 * - As soon as a "real" console is registered, all bootconsoles
2218 * will be unregistered automatically.
2219 * - Once a "real" console is registered, any attempt to register a
2220 * bootconsoles will be rejected
2221 */
2222void register_console(struct console *newcon)
2223{
2224 int i;
2225 unsigned long flags;
2226 struct console *bcon = NULL;
2227 struct console_cmdline *c;
2228
2229 if (console_drivers)
2230 for_each_console(bcon)
2231 if (WARN(bcon == newcon,
2232 "console '%s%d' already registered\n",
2233 bcon->name, bcon->index))
2234 return;
2235
2236 /*
2237 * before we register a new CON_BOOT console, make sure we don't
2238 * already have a valid console
2239 */
2240 if (console_drivers && newcon->flags & CON_BOOT) {
2241 /* find the last or real console */
2242 for_each_console(bcon) {
2243 if (!(bcon->flags & CON_BOOT)) {
2244 printk(KERN_INFO "Too late to register bootconsole %s%d\n",
2245 newcon->name, newcon->index);
2246 return;
2247 }
2248 }
2249 }
2250
2251 if (console_drivers && console_drivers->flags & CON_BOOT)
2252 bcon = console_drivers;
2253
2254 if (preferred_console < 0 || bcon || !console_drivers)
2255 preferred_console = selected_console;
2256
2257 if (newcon->early_setup)
2258 newcon->early_setup();
2259
2260 /*
2261 * See if we want to use this console driver. If we
2262 * didn't select a console we take the first one
2263 * that registers here.
2264 */
2265 if (preferred_console < 0) {
2266 if (newcon->index < 0)
2267 newcon->index = 0;
2268 if (newcon->setup == NULL ||
2269 newcon->setup(newcon, NULL) == 0) {
2270 newcon->flags |= CON_ENABLED;
2271 if (newcon->device) {
2272 newcon->flags |= CON_CONSDEV;
2273 preferred_console = 0;
2274 }
2275 }
2276 }
2277
2278 /*
2279 * See if this console matches one we selected on
2280 * the command line.
2281 */
2282 for (i = 0, c = console_cmdline;
2283 i < MAX_CMDLINECONSOLES && c->name[0];
2284 i++, c++) {
2285 if (strcmp(c->name, newcon->name) != 0)
2286 continue;
2287 if (newcon->index >= 0 &&
2288 newcon->index != c->index)
2289 continue;
2290 if (newcon->index < 0)
2291 newcon->index = c->index;
2292
2293 if (_braille_register_console(newcon, c))
2294 return;
2295
2296 if (newcon->setup &&
2297 newcon->setup(newcon, console_cmdline[i].options) != 0)
2298 break;
2299 newcon->flags |= CON_ENABLED;
2300 newcon->index = c->index;
2301 if (i == selected_console) {
2302 newcon->flags |= CON_CONSDEV;
2303 preferred_console = selected_console;
2304 }
2305 break;
2306 }
2307
2308 if (!(newcon->flags & CON_ENABLED))
2309 return;
2310
2311 /*
2312 * If we have a bootconsole, and are switching to a real console,
2313 * don't print everything out again, since when the boot console, and
2314 * the real console are the same physical device, it's annoying to
2315 * see the beginning boot messages twice
2316 */
2317 if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
2318 newcon->flags &= ~CON_PRINTBUFFER;
2319
2320 /*
2321 * Put this console in the list - keep the
2322 * preferred driver at the head of the list.
2323 */
2324 console_lock();
2325 if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
2326 newcon->next = console_drivers;
2327 console_drivers = newcon;
2328 if (newcon->next)
2329 newcon->next->flags &= ~CON_CONSDEV;
2330 } else {
2331 newcon->next = console_drivers->next;
2332 console_drivers->next = newcon;
2333 }
2334 if (newcon->flags & CON_PRINTBUFFER) {
2335 /*
2336 * console_unlock(); will print out the buffered messages
2337 * for us.
2338 */
2339 raw_spin_lock_irqsave(&logbuf_lock, flags);
2340 console_seq = syslog_seq;
2341 console_idx = syslog_idx;
2342 console_prev = syslog_prev;
2343 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2344 /*
2345 * We're about to replay the log buffer. Only do this to the
2346 * just-registered console to avoid excessive message spam to
2347 * the already-registered consoles.
2348 */
2349 exclusive_console = newcon;
2350 }
2351 console_unlock();
2352 console_sysfs_notify();
2353
2354 /*
2355 * By unregistering the bootconsoles after we enable the real console
2356 * we get the "console xxx enabled" message on all the consoles -
2357 * boot consoles, real consoles, etc - this is to ensure that end
2358 * users know there might be something in the kernel's log buffer that
2359 * went to the bootconsole (that they do not see on the real console)
2360 */
2361 if (bcon &&
2362 ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
2363 !keep_bootcon) {
2364 /* we need to iterate through twice, to make sure we print
2365 * everything out, before we unregister the console(s)
2366 */
2367 printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n",
2368 newcon->name, newcon->index);
2369 for_each_console(bcon)
2370 if (bcon->flags & CON_BOOT)
2371 unregister_console(bcon);
2372 } else {
2373 printk(KERN_INFO "%sconsole [%s%d] enabled\n",
2374 (newcon->flags & CON_BOOT) ? "boot" : "" ,
2375 newcon->name, newcon->index);
2376 }
2377}
2378EXPORT_SYMBOL(register_console);
2379
2380int unregister_console(struct console *console)
2381{
2382 struct console *a, *b;
2383 int res;
2384
2385 res = _braille_unregister_console(console);
2386 if (res)
2387 return res;
2388
2389 res = 1;
2390 console_lock();
2391 if (console_drivers == console) {
2392 console_drivers=console->next;
2393 res = 0;
2394 } else if (console_drivers) {
2395 for (a=console_drivers->next, b=console_drivers ;
2396 a; b=a, a=b->next) {
2397 if (a == console) {
2398 b->next = a->next;
2399 res = 0;
2400 break;
2401 }
2402 }
2403 }
2404
2405 /*
2406 * If this isn't the last console and it has CON_CONSDEV set, we
2407 * need to set it on the next preferred console.
2408 */
2409 if (console_drivers != NULL && console->flags & CON_CONSDEV)
2410 console_drivers->flags |= CON_CONSDEV;
2411
2412 console_unlock();
2413 console_sysfs_notify();
2414 return res;
2415}
2416EXPORT_SYMBOL(unregister_console);
2417
2418static int __init printk_late_init(void)
2419{
2420 struct console *con;
2421
2422 for_each_console(con) {
2423 if (!keep_bootcon && con->flags & CON_BOOT) {
2424 printk(KERN_INFO "turn off boot console %s%d\n",
2425 con->name, con->index);
2426 unregister_console(con);
2427 }
2428 }
2429 hotcpu_notifier(console_cpu_notify, 0);
2430 return 0;
2431}
2432late_initcall(printk_late_init);
2433
2434#if defined CONFIG_PRINTK
2435/*
2436 * Delayed printk version, for scheduler-internal messages:
2437 */
2438#define PRINTK_BUF_SIZE 512
2439
2440#define PRINTK_PENDING_WAKEUP 0x01
2441#define PRINTK_PENDING_SCHED 0x02
2442
2443static DEFINE_PER_CPU(int, printk_pending);
2444static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
2445
2446static void wake_up_klogd_work_func(struct irq_work *irq_work)
2447{
2448 int pending = __this_cpu_xchg(printk_pending, 0);
2449
2450 if (pending & PRINTK_PENDING_SCHED) {
2451 char *buf = __get_cpu_var(printk_sched_buf);
2452 printk(KERN_WARNING "[sched_delayed] %s", buf);
2453 }
2454
2455 if (pending & PRINTK_PENDING_WAKEUP)
2456 wake_up_interruptible(&log_wait);
2457}
2458
2459static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
2460 .func = wake_up_klogd_work_func,
2461 .flags = IRQ_WORK_LAZY,
2462};
2463
2464void wake_up_klogd(void)
2465{
2466 preempt_disable();
2467 if (waitqueue_active(&log_wait)) {
2468 this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
2469 irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
2470 }
2471 preempt_enable();
2472}
2473
2474int printk_sched(const char *fmt, ...)
2475{
2476 unsigned long flags;
2477 va_list args;
2478 char *buf;
2479 int r;
2480
2481 local_irq_save(flags);
2482 buf = __get_cpu_var(printk_sched_buf);
2483
2484 va_start(args, fmt);
2485 r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
2486 va_end(args);
2487
2488 __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
2489 irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
2490 local_irq_restore(flags);
2491
2492 return r;
2493}
2494
2495/*
2496 * printk rate limiting, lifted from the networking subsystem.
2497 *
2498 * This enforces a rate limit: not more than 10 kernel messages
2499 * every 5s to make a denial-of-service attack impossible.
2500 */
2501DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
2502
2503int __printk_ratelimit(const char *func)
2504{
2505 return ___ratelimit(&printk_ratelimit_state, func);
2506}
2507EXPORT_SYMBOL(__printk_ratelimit);
2508
2509/**
2510 * printk_timed_ratelimit - caller-controlled printk ratelimiting
2511 * @caller_jiffies: pointer to caller's state
2512 * @interval_msecs: minimum interval between prints
2513 *
2514 * printk_timed_ratelimit() returns true if more than @interval_msecs
2515 * milliseconds have elapsed since the last time printk_timed_ratelimit()
2516 * returned true.
2517 */
2518bool printk_timed_ratelimit(unsigned long *caller_jiffies,
2519 unsigned int interval_msecs)
2520{
2521 if (*caller_jiffies == 0
2522 || !time_in_range(jiffies, *caller_jiffies,
2523 *caller_jiffies
2524 + msecs_to_jiffies(interval_msecs))) {
2525 *caller_jiffies = jiffies;
2526 return true;
2527 }
2528 return false;
2529}
2530EXPORT_SYMBOL(printk_timed_ratelimit);
2531
2532static DEFINE_SPINLOCK(dump_list_lock);
2533static LIST_HEAD(dump_list);
2534
2535/**
2536 * kmsg_dump_register - register a kernel log dumper.
2537 * @dumper: pointer to the kmsg_dumper structure
2538 *
2539 * Adds a kernel log dumper to the system. The dump callback in the
2540 * structure will be called when the kernel oopses or panics and must be
2541 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
2542 */
2543int kmsg_dump_register(struct kmsg_dumper *dumper)
2544{
2545 unsigned long flags;
2546 int err = -EBUSY;
2547
2548 /* The dump callback needs to be set */
2549 if (!dumper->dump)
2550 return -EINVAL;
2551
2552 spin_lock_irqsave(&dump_list_lock, flags);
2553 /* Don't allow registering multiple times */
2554 if (!dumper->registered) {
2555 dumper->registered = 1;
2556 list_add_tail_rcu(&dumper->list, &dump_list);
2557 err = 0;
2558 }
2559 spin_unlock_irqrestore(&dump_list_lock, flags);
2560
2561 return err;
2562}
2563EXPORT_SYMBOL_GPL(kmsg_dump_register);
2564
2565/**
2566 * kmsg_dump_unregister - unregister a kmsg dumper.
2567 * @dumper: pointer to the kmsg_dumper structure
2568 *
2569 * Removes a dump device from the system. Returns zero on success and
2570 * %-EINVAL otherwise.
2571 */
2572int kmsg_dump_unregister(struct kmsg_dumper *dumper)
2573{
2574 unsigned long flags;
2575 int err = -EINVAL;
2576
2577 spin_lock_irqsave(&dump_list_lock, flags);
2578 if (dumper->registered) {
2579 dumper->registered = 0;
2580 list_del_rcu(&dumper->list);
2581 err = 0;
2582 }
2583 spin_unlock_irqrestore(&dump_list_lock, flags);
2584 synchronize_rcu();
2585
2586 return err;
2587}
2588EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
2589
2590static bool always_kmsg_dump;
2591module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
2592
2593/**
2594 * kmsg_dump - dump kernel log to kernel message dumpers.
2595 * @reason: the reason (oops, panic etc) for dumping
2596 *
2597 * Call each of the registered dumper's dump() callback, which can
2598 * retrieve the kmsg records with kmsg_dump_get_line() or
2599 * kmsg_dump_get_buffer().
2600 */
2601void kmsg_dump(enum kmsg_dump_reason reason)
2602{
2603 struct kmsg_dumper *dumper;
2604 unsigned long flags;
2605
2606 if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
2607 return;
2608
2609 rcu_read_lock();
2610 list_for_each_entry_rcu(dumper, &dump_list, list) {
2611 if (dumper->max_reason && reason > dumper->max_reason)
2612 continue;
2613
2614 /* initialize iterator with data about the stored records */
2615 dumper->active = true;
2616
2617 raw_spin_lock_irqsave(&logbuf_lock, flags);
2618 dumper->cur_seq = clear_seq;
2619 dumper->cur_idx = clear_idx;
2620 dumper->next_seq = log_next_seq;
2621 dumper->next_idx = log_next_idx;
2622 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2623
2624 /* invoke dumper which will iterate over records */
2625 dumper->dump(dumper, reason);
2626
2627 /* reset iterator */
2628 dumper->active = false;
2629 }
2630 rcu_read_unlock();
2631}
2632
2633/**
2634 * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
2635 * @dumper: registered kmsg dumper
2636 * @syslog: include the "<4>" prefixes
2637 * @line: buffer to copy the line to
2638 * @size: maximum size of the buffer
2639 * @len: length of line placed into buffer
2640 *
2641 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2642 * record, and copy one record into the provided buffer.
2643 *
2644 * Consecutive calls will return the next available record moving
2645 * towards the end of the buffer with the youngest messages.
2646 *
2647 * A return value of FALSE indicates that there are no more records to
2648 * read.
2649 *
2650 * The function is similar to kmsg_dump_get_line(), but grabs no locks.
2651 */
2652bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
2653 char *line, size_t size, size_t *len)
2654{
2655 struct printk_log *msg;
2656 size_t l = 0;
2657 bool ret = false;
2658
2659 if (!dumper->active)
2660 goto out;
2661
2662 if (dumper->cur_seq < log_first_seq) {
2663 /* messages are gone, move to first available one */
2664 dumper->cur_seq = log_first_seq;
2665 dumper->cur_idx = log_first_idx;
2666 }
2667
2668 /* last entry */
2669 if (dumper->cur_seq >= log_next_seq)
2670 goto out;
2671
2672 msg = log_from_idx(dumper->cur_idx);
2673 l = msg_print_text(msg, 0, syslog, line, size);
2674
2675 dumper->cur_idx = log_next(dumper->cur_idx);
2676 dumper->cur_seq++;
2677 ret = true;
2678out:
2679 if (len)
2680 *len = l;
2681 return ret;
2682}
2683
2684/**
2685 * kmsg_dump_get_line - retrieve one kmsg log line
2686 * @dumper: registered kmsg dumper
2687 * @syslog: include the "<4>" prefixes
2688 * @line: buffer to copy the line to
2689 * @size: maximum size of the buffer
2690 * @len: length of line placed into buffer
2691 *
2692 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2693 * record, and copy one record into the provided buffer.
2694 *
2695 * Consecutive calls will return the next available record moving
2696 * towards the end of the buffer with the youngest messages.
2697 *
2698 * A return value of FALSE indicates that there are no more records to
2699 * read.
2700 */
2701bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
2702 char *line, size_t size, size_t *len)
2703{
2704 unsigned long flags;
2705 bool ret;
2706
2707 raw_spin_lock_irqsave(&logbuf_lock, flags);
2708 ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
2709 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2710
2711 return ret;
2712}
2713EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
2714
2715/**
2716 * kmsg_dump_get_buffer - copy kmsg log lines
2717 * @dumper: registered kmsg dumper
2718 * @syslog: include the "<4>" prefixes
2719 * @buf: buffer to copy the line to
2720 * @size: maximum size of the buffer
2721 * @len: length of line placed into buffer
2722 *
2723 * Start at the end of the kmsg buffer and fill the provided buffer
2724 * with as many of the the *youngest* kmsg records that fit into it.
2725 * If the buffer is large enough, all available kmsg records will be
2726 * copied with a single call.
2727 *
2728 * Consecutive calls will fill the buffer with the next block of
2729 * available older records, not including the earlier retrieved ones.
2730 *
2731 * A return value of FALSE indicates that there are no more records to
2732 * read.
2733 */
2734bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
2735 char *buf, size_t size, size_t *len)
2736{
2737 unsigned long flags;
2738 u64 seq;
2739 u32 idx;
2740 u64 next_seq;
2741 u32 next_idx;
2742 enum log_flags prev;
2743 size_t l = 0;
2744 bool ret = false;
2745
2746 if (!dumper->active)
2747 goto out;
2748
2749 raw_spin_lock_irqsave(&logbuf_lock, flags);
2750 if (dumper->cur_seq < log_first_seq) {
2751 /* messages are gone, move to first available one */
2752 dumper->cur_seq = log_first_seq;
2753 dumper->cur_idx = log_first_idx;
2754 }
2755
2756 /* last entry */
2757 if (dumper->cur_seq >= dumper->next_seq) {
2758 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2759 goto out;
2760 }
2761
2762 /* calculate length of entire buffer */
2763 seq = dumper->cur_seq;
2764 idx = dumper->cur_idx;
2765 prev = 0;
2766 while (seq < dumper->next_seq) {
2767 struct printk_log *msg = log_from_idx(idx);
2768
2769 l += msg_print_text(msg, prev, true, NULL, 0);
2770 idx = log_next(idx);
2771 seq++;
2772 prev = msg->flags;
2773 }
2774
2775 /* move first record forward until length fits into the buffer */
2776 seq = dumper->cur_seq;
2777 idx = dumper->cur_idx;
2778 prev = 0;
2779 while (l > size && seq < dumper->next_seq) {
2780 struct printk_log *msg = log_from_idx(idx);
2781
2782 l -= msg_print_text(msg, prev, true, NULL, 0);
2783 idx = log_next(idx);
2784 seq++;
2785 prev = msg->flags;
2786 }
2787
2788 /* last message in next interation */
2789 next_seq = seq;
2790 next_idx = idx;
2791
2792 l = 0;
2793 prev = 0;
2794 while (seq < dumper->next_seq) {
2795 struct printk_log *msg = log_from_idx(idx);
2796
2797 l += msg_print_text(msg, prev, syslog, buf + l, size - l);
2798 idx = log_next(idx);
2799 seq++;
2800 prev = msg->flags;
2801 }
2802
2803 dumper->next_seq = next_seq;
2804 dumper->next_idx = next_idx;
2805 ret = true;
2806 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2807out:
2808 if (len)
2809 *len = l;
2810 return ret;
2811}
2812EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
2813
2814/**
2815 * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
2816 * @dumper: registered kmsg dumper
2817 *
2818 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2819 * kmsg_dump_get_buffer() can be called again and used multiple
2820 * times within the same dumper.dump() callback.
2821 *
2822 * The function is similar to kmsg_dump_rewind(), but grabs no locks.
2823 */
2824void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
2825{
2826 dumper->cur_seq = clear_seq;
2827 dumper->cur_idx = clear_idx;
2828 dumper->next_seq = log_next_seq;
2829 dumper->next_idx = log_next_idx;
2830}
2831
2832/**
2833 * kmsg_dump_rewind - reset the interator
2834 * @dumper: registered kmsg dumper
2835 *
2836 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2837 * kmsg_dump_get_buffer() can be called again and used multiple
2838 * times within the same dumper.dump() callback.
2839 */
2840void kmsg_dump_rewind(struct kmsg_dumper *dumper)
2841{
2842 unsigned long flags;
2843
2844 raw_spin_lock_irqsave(&logbuf_lock, flags);
2845 kmsg_dump_rewind_nolock(dumper);
2846 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2847}
2848EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
2849
2850static char dump_stack_arch_desc_str[128];
2851
2852/**
2853 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
2854 * @fmt: printf-style format string
2855 * @...: arguments for the format string
2856 *
2857 * The configured string will be printed right after utsname during task
2858 * dumps. Usually used to add arch-specific system identifiers. If an
2859 * arch wants to make use of such an ID string, it should initialize this
2860 * as soon as possible during boot.
2861 */
2862void __init dump_stack_set_arch_desc(const char *fmt, ...)
2863{
2864 va_list args;
2865
2866 va_start(args, fmt);
2867 vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
2868 fmt, args);
2869 va_end(args);
2870}
2871
2872/**
2873 * dump_stack_print_info - print generic debug info for dump_stack()
2874 * @log_lvl: log level
2875 *
2876 * Arch-specific dump_stack() implementations can use this function to
2877 * print out the same debug information as the generic dump_stack().
2878 */
2879void dump_stack_print_info(const char *log_lvl)
2880{
2881 printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
2882 log_lvl, raw_smp_processor_id(), current->pid, current->comm,
2883 print_tainted(), init_utsname()->release,
2884 (int)strcspn(init_utsname()->version, " "),
2885 init_utsname()->version);
2886
2887 if (dump_stack_arch_desc_str[0] != '\0')
2888 printk("%sHardware name: %s\n",
2889 log_lvl, dump_stack_arch_desc_str);
2890
2891 print_worker_info(log_lvl, current);
2892}
2893
2894/**
2895 * show_regs_print_info - print generic debug info for show_regs()
2896 * @log_lvl: log level
2897 *
2898 * show_regs() implementations can use this function to print out generic
2899 * debug information.
2900 */
2901void show_regs_print_info(const char *log_lvl)
2902{
2903 dump_stack_print_info(log_lvl);
2904
2905 printk("%stask: %p ti: %p task.ti: %p\n",
2906 log_lvl, current, current_thread_info(),
2907 task_thread_info(current));
2908}
2909
2910#endif
generated by cgit v1.2.2 (git 2.25.0) at 2025-02-18 02:21:17 -0500