2 * linux/kernel/printk.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
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).
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
19 #include <linux/kernel.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>
49 #include <asm/uaccess.h>
51 #define CREATE_TRACE_POINTS
52 #include <trace/events/printk.h>
54 #include "console_cmdline.h"
57 /* printk's without a loglevel use this.. */
58 #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
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 */
64 int 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 */
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.
76 EXPORT_SYMBOL(oops_in_progress
);
79 * console_sem protects the console_drivers list, and also
80 * provides serialisation for access to the entire console
83 static DEFINE_SEMAPHORE(console_sem
);
84 struct console
*console_drivers
;
85 EXPORT_SYMBOL_GPL(console_drivers
);
88 static struct lockdep_map console_lock_dep_map
= {
89 .name
= "console_lock"
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
101 static int console_locked
, console_suspended
;
104 * If exclusive_console is non-NULL then only this console is to be printed to.
106 static struct console
*exclusive_console
;
109 * Array of consoles built from command line options (console=)
112 #define MAX_CMDLINECONSOLES 8
114 static struct console_cmdline console_cmdline
[MAX_CMDLINECONSOLES
];
116 static int selected_console
= -1;
117 static int preferred_console
= -1;
118 int console_set_on_cmdline
;
119 EXPORT_SYMBOL(console_set_on_cmdline
);
121 /* Flag: console code may call schedule() */
122 static int console_may_schedule
;
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.
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
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.
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.
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
147 * Optionally, a message can carry a dictionary of properties (key/value pairs),
148 * to provide userspace with a machine-readable message context.
150 * Examples for well-defined, commonly used property names are:
151 * DEVICE=b12:8 device identifier
155 * +sound:card0 subsystem:devname
156 * SUBSYSTEM=pci driver-core subsystem name
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.
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"
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"
174 * 0032 00 00 00 padding to next message header
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.
180 * /dev/kmsg exports the structured data in the following line format:
181 * "level,sequnum,timestamp;<message text>\n"
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.
187 * Users of the export format should ignore possible additional values
188 * separated by ',', and find the message after the ';' character.
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 */
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 */
209 * The logbuf_lock protects kmsg buffer, indices, counters. It is also
210 * used in interesting ways to provide interlocking in console_unlock();
212 static DEFINE_RAW_SPINLOCK(logbuf_lock
);
215 DECLARE_WAIT_QUEUE_HEAD(log_wait
);
216 /* the next printk record to read by syslog(READ) or /proc/kmsg */
217 static u64 syslog_seq
;
218 static u32 syslog_idx
;
219 static enum log_flags syslog_prev
;
220 static size_t syslog_partial
;
222 /* index and sequence number of the first record stored in the buffer */
223 static u64 log_first_seq
;
224 static u32 log_first_idx
;
226 /* index and sequence number of the next record to store in the buffer */
227 static u64 log_next_seq
;
228 static u32 log_next_idx
;
230 /* the next printk record to write to the console */
231 static u64 console_seq
;
232 static u32 console_idx
;
233 static enum log_flags console_prev
;
235 /* the next printk record to read after the last 'clear' command */
236 static u64 clear_seq
;
237 static u32 clear_idx
;
239 #define PREFIX_MAX 32
240 #define LOG_LINE_MAX 1024 - PREFIX_MAX
243 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
246 #define LOG_ALIGN __alignof__(struct printk_log)
248 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
249 static char __log_buf
[__LOG_BUF_LEN
] __aligned(LOG_ALIGN
);
250 static char *log_buf
= __log_buf
;
251 static u32 log_buf_len
= __LOG_BUF_LEN
;
253 /* cpu currently holding logbuf_lock */
254 static volatile unsigned int logbuf_cpu
= UINT_MAX
;
256 /* human readable text of the record */
257 static char *log_text(const struct printk_log
*msg
)
259 return (char *)msg
+ sizeof(struct printk_log
);
262 /* optional key/value pair dictionary attached to the record */
263 static char *log_dict(const struct printk_log
*msg
)
265 return (char *)msg
+ sizeof(struct printk_log
) + msg
->text_len
;
268 /* get record by index; idx must point to valid msg */
269 static struct printk_log
*log_from_idx(u32 idx
)
271 struct printk_log
*msg
= (struct printk_log
*)(log_buf
+ idx
);
274 * A length == 0 record is the end of buffer marker. Wrap around and
275 * read the message at the start of the buffer.
278 return (struct printk_log
*)log_buf
;
282 /* get next record; idx must point to valid msg */
283 static u32
log_next(u32 idx
)
285 struct printk_log
*msg
= (struct printk_log
*)(log_buf
+ idx
);
287 /* length == 0 indicates the end of the buffer; wrap */
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.
294 msg
= (struct printk_log
*)log_buf
;
297 return idx
+ msg
->len
;
301 * Check whether there is enough free space for the given message.
303 * The same values of first_idx and next_idx mean that the buffer
304 * is either empty or full.
306 * If the buffer is empty, we must respect the position of the indexes.
307 * They cannot be reset to the beginning of the buffer.
309 static int logbuf_has_space(u32 msg_size
, bool empty
)
313 if (log_next_idx
> log_first_idx
|| empty
)
314 free
= max(log_buf_len
- log_next_idx
, log_first_idx
);
316 free
= log_first_idx
- log_next_idx
;
319 * We need space also for an empty header that signalizes wrapping
322 return free
>= msg_size
+ sizeof(struct printk_log
);
325 static int log_make_free_space(u32 msg_size
)
327 while (log_first_seq
< log_next_seq
) {
328 if (logbuf_has_space(msg_size
, false))
330 /* drop old messages until we have enough continuous space */
331 log_first_idx
= log_next(log_first_idx
);
335 /* sequence numbers are equal, so the log buffer is empty */
336 if (logbuf_has_space(msg_size
, true))
342 /* compute the message size including the padding bytes */
343 static u32
msg_used_size(u16 text_len
, u16 dict_len
, u32
*pad_len
)
347 size
= sizeof(struct printk_log
) + text_len
+ dict_len
;
348 *pad_len
= (-size
) & (LOG_ALIGN
- 1);
355 * Define how much of the log buffer we could take at maximum. The value
356 * must be greater than two. Note that only half of the buffer is available
357 * when the index points to the middle.
359 #define MAX_LOG_TAKE_PART 4
360 static const char trunc_msg
[] = "<truncated>";
362 static u32
truncate_msg(u16
*text_len
, u16
*trunc_msg_len
,
363 u16
*dict_len
, u32
*pad_len
)
366 * The message should not take the whole buffer. Otherwise, it might
367 * get removed too soon.
369 u32 max_text_len
= log_buf_len
/ MAX_LOG_TAKE_PART
;
370 if (*text_len
> max_text_len
)
371 *text_len
= max_text_len
;
372 /* enable the warning message */
373 *trunc_msg_len
= strlen(trunc_msg
);
374 /* disable the "dict" completely */
376 /* compute the size again, count also the warning message */
377 return msg_used_size(*text_len
+ *trunc_msg_len
, 0, pad_len
);
380 /* insert record into the buffer, discard old ones, update heads */
381 static int log_store(int facility
, int level
,
382 enum log_flags flags
, u64 ts_nsec
,
383 const char *dict
, u16 dict_len
,
384 const char *text
, u16 text_len
)
386 struct printk_log
*msg
;
388 u16 trunc_msg_len
= 0;
390 /* number of '\0' padding bytes to next message */
391 size
= msg_used_size(text_len
, dict_len
, &pad_len
);
393 if (log_make_free_space(size
)) {
394 /* truncate the message if it is too long for empty buffer */
395 size
= truncate_msg(&text_len
, &trunc_msg_len
,
396 &dict_len
, &pad_len
);
397 /* survive when the log buffer is too small for trunc_msg */
398 if (log_make_free_space(size
))
402 if (log_next_idx
+ size
+ sizeof(struct printk_log
) > log_buf_len
) {
404 * This message + an additional empty header does not fit
405 * at the end of the buffer. Add an empty header with len == 0
406 * to signify a wrap around.
408 memset(log_buf
+ log_next_idx
, 0, sizeof(struct printk_log
));
413 msg
= (struct printk_log
*)(log_buf
+ log_next_idx
);
414 memcpy(log_text(msg
), text
, text_len
);
415 msg
->text_len
= text_len
;
417 memcpy(log_text(msg
) + text_len
, trunc_msg
, trunc_msg_len
);
418 msg
->text_len
+= trunc_msg_len
;
420 memcpy(log_dict(msg
), dict
, dict_len
);
421 msg
->dict_len
= dict_len
;
422 msg
->facility
= facility
;
423 msg
->level
= level
& 7;
424 msg
->flags
= flags
& 0x1f;
426 msg
->ts_nsec
= ts_nsec
;
428 msg
->ts_nsec
= local_clock();
429 memset(log_dict(msg
) + dict_len
, 0, pad_len
);
433 log_next_idx
+= msg
->len
;
436 return msg
->text_len
;
439 #ifdef CONFIG_SECURITY_DMESG_RESTRICT
440 int dmesg_restrict
= 1;
445 static int syslog_action_restricted(int type
)
450 * Unless restricted, we allow "read all" and "get buffer size"
453 return type
!= SYSLOG_ACTION_READ_ALL
&&
454 type
!= SYSLOG_ACTION_SIZE_BUFFER
;
457 static int check_syslog_permissions(int type
, bool from_file
)
460 * If this is from /proc/kmsg and we've already opened it, then we've
461 * already done the capabilities checks at open time.
463 if (from_file
&& type
!= SYSLOG_ACTION_OPEN
)
466 if (syslog_action_restricted(type
)) {
467 if (capable(CAP_SYSLOG
))
470 * For historical reasons, accept CAP_SYS_ADMIN too, with
473 if (capable(CAP_SYS_ADMIN
)) {
474 pr_warn_once("%s (%d): Attempt to access syslog with "
475 "CAP_SYS_ADMIN but no CAP_SYSLOG "
477 current
->comm
, task_pid_nr(current
));
482 return security_syslog(type
);
486 /* /dev/kmsg - userspace message inject/listen interface */
487 struct devkmsg_user
{
495 static ssize_t
devkmsg_writev(struct kiocb
*iocb
, const struct iovec
*iv
,
496 unsigned long count
, loff_t pos
)
500 int level
= default_message_loglevel
;
501 int facility
= 1; /* LOG_USER */
502 size_t len
= iov_length(iv
, count
);
505 if (len
> LOG_LINE_MAX
)
507 buf
= kmalloc(len
+1, GFP_KERNEL
);
512 for (i
= 0; i
< count
; i
++) {
513 if (copy_from_user(line
, iv
[i
].iov_base
, iv
[i
].iov_len
)) {
517 line
+= iv
[i
].iov_len
;
521 * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
522 * the decimal value represents 32bit, the lower 3 bit are the log
523 * level, the rest are the log facility.
525 * If no prefix or no userspace facility is specified, we
526 * enforce LOG_USER, to be able to reliably distinguish
527 * kernel-generated messages from userspace-injected ones.
530 if (line
[0] == '<') {
533 i
= simple_strtoul(line
+1, &endp
, 10);
534 if (endp
&& endp
[0] == '>') {
545 printk_emit(facility
, level
, NULL
, 0, "%s", line
);
551 static ssize_t
devkmsg_read(struct file
*file
, char __user
*buf
,
552 size_t count
, loff_t
*ppos
)
554 struct devkmsg_user
*user
= file
->private_data
;
555 struct printk_log
*msg
;
565 ret
= mutex_lock_interruptible(&user
->lock
);
568 raw_spin_lock_irq(&logbuf_lock
);
569 while (user
->seq
== log_next_seq
) {
570 if (file
->f_flags
& O_NONBLOCK
) {
572 raw_spin_unlock_irq(&logbuf_lock
);
576 raw_spin_unlock_irq(&logbuf_lock
);
577 ret
= wait_event_interruptible(log_wait
,
578 user
->seq
!= log_next_seq
);
581 raw_spin_lock_irq(&logbuf_lock
);
584 if (user
->seq
< log_first_seq
) {
585 /* our last seen message is gone, return error and reset */
586 user
->idx
= log_first_idx
;
587 user
->seq
= log_first_seq
;
589 raw_spin_unlock_irq(&logbuf_lock
);
593 msg
= log_from_idx(user
->idx
);
594 ts_usec
= msg
->ts_nsec
;
595 do_div(ts_usec
, 1000);
598 * If we couldn't merge continuation line fragments during the print,
599 * export the stored flags to allow an optional external merge of the
600 * records. Merging the records isn't always neccessarily correct, like
601 * when we hit a race during printing. In most cases though, it produces
602 * better readable output. 'c' in the record flags mark the first
603 * fragment of a line, '+' the following.
605 if (msg
->flags
& LOG_CONT
&& !(user
->prev
& LOG_CONT
))
607 else if ((msg
->flags
& LOG_CONT
) ||
608 ((user
->prev
& LOG_CONT
) && !(msg
->flags
& LOG_PREFIX
)))
611 len
= sprintf(user
->buf
, "%u,%llu,%llu,%c;",
612 (msg
->facility
<< 3) | msg
->level
,
613 user
->seq
, ts_usec
, cont
);
614 user
->prev
= msg
->flags
;
616 /* escape non-printable characters */
617 for (i
= 0; i
< msg
->text_len
; i
++) {
618 unsigned char c
= log_text(msg
)[i
];
620 if (c
< ' ' || c
>= 127 || c
== '\\')
621 len
+= sprintf(user
->buf
+ len
, "\\x%02x", c
);
623 user
->buf
[len
++] = c
;
625 user
->buf
[len
++] = '\n';
630 for (i
= 0; i
< msg
->dict_len
; i
++) {
631 unsigned char c
= log_dict(msg
)[i
];
634 user
->buf
[len
++] = ' ';
639 user
->buf
[len
++] = '\n';
644 if (c
< ' ' || c
>= 127 || c
== '\\') {
645 len
+= sprintf(user
->buf
+ len
, "\\x%02x", c
);
649 user
->buf
[len
++] = c
;
651 user
->buf
[len
++] = '\n';
654 user
->idx
= log_next(user
->idx
);
656 raw_spin_unlock_irq(&logbuf_lock
);
663 if (copy_to_user(buf
, user
->buf
, len
)) {
669 mutex_unlock(&user
->lock
);
673 static loff_t
devkmsg_llseek(struct file
*file
, loff_t offset
, int whence
)
675 struct devkmsg_user
*user
= file
->private_data
;
683 raw_spin_lock_irq(&logbuf_lock
);
686 /* the first record */
687 user
->idx
= log_first_idx
;
688 user
->seq
= log_first_seq
;
692 * The first record after the last SYSLOG_ACTION_CLEAR,
693 * like issued by 'dmesg -c'. Reading /dev/kmsg itself
694 * changes no global state, and does not clear anything.
696 user
->idx
= clear_idx
;
697 user
->seq
= clear_seq
;
700 /* after the last record */
701 user
->idx
= log_next_idx
;
702 user
->seq
= log_next_seq
;
707 raw_spin_unlock_irq(&logbuf_lock
);
711 static unsigned int devkmsg_poll(struct file
*file
, poll_table
*wait
)
713 struct devkmsg_user
*user
= file
->private_data
;
717 return POLLERR
|POLLNVAL
;
719 poll_wait(file
, &log_wait
, wait
);
721 raw_spin_lock_irq(&logbuf_lock
);
722 if (user
->seq
< log_next_seq
) {
723 /* return error when data has vanished underneath us */
724 if (user
->seq
< log_first_seq
)
725 ret
= POLLIN
|POLLRDNORM
|POLLERR
|POLLPRI
;
727 ret
= POLLIN
|POLLRDNORM
;
729 raw_spin_unlock_irq(&logbuf_lock
);
734 static int devkmsg_open(struct inode
*inode
, struct file
*file
)
736 struct devkmsg_user
*user
;
739 /* write-only does not need any file context */
740 if ((file
->f_flags
& O_ACCMODE
) == O_WRONLY
)
743 err
= check_syslog_permissions(SYSLOG_ACTION_READ_ALL
,
748 user
= kmalloc(sizeof(struct devkmsg_user
), GFP_KERNEL
);
752 mutex_init(&user
->lock
);
754 raw_spin_lock_irq(&logbuf_lock
);
755 user
->idx
= log_first_idx
;
756 user
->seq
= log_first_seq
;
757 raw_spin_unlock_irq(&logbuf_lock
);
759 file
->private_data
= user
;
763 static int devkmsg_release(struct inode
*inode
, struct file
*file
)
765 struct devkmsg_user
*user
= file
->private_data
;
770 mutex_destroy(&user
->lock
);
775 const struct file_operations kmsg_fops
= {
776 .open
= devkmsg_open
,
777 .read
= devkmsg_read
,
778 .aio_write
= devkmsg_writev
,
779 .llseek
= devkmsg_llseek
,
780 .poll
= devkmsg_poll
,
781 .release
= devkmsg_release
,
786 * This appends the listed symbols to /proc/vmcore
788 * /proc/vmcore is used by various utilities, like crash and makedumpfile to
789 * obtain access to symbols that are otherwise very difficult to locate. These
790 * symbols are specifically used so that utilities can access and extract the
791 * dmesg log from a vmcore file after a crash.
793 void log_buf_kexec_setup(void)
795 VMCOREINFO_SYMBOL(log_buf
);
796 VMCOREINFO_SYMBOL(log_buf_len
);
797 VMCOREINFO_SYMBOL(log_first_idx
);
798 VMCOREINFO_SYMBOL(log_next_idx
);
800 * Export struct printk_log size and field offsets. User space tools can
801 * parse it and detect any changes to structure down the line.
803 VMCOREINFO_STRUCT_SIZE(printk_log
);
804 VMCOREINFO_OFFSET(printk_log
, ts_nsec
);
805 VMCOREINFO_OFFSET(printk_log
, len
);
806 VMCOREINFO_OFFSET(printk_log
, text_len
);
807 VMCOREINFO_OFFSET(printk_log
, dict_len
);
811 /* requested log_buf_len from kernel cmdline */
812 static unsigned long __initdata new_log_buf_len
;
814 /* save requested log_buf_len since it's too early to process it */
815 static int __init
log_buf_len_setup(char *str
)
817 unsigned size
= memparse(str
, &str
);
820 size
= roundup_pow_of_two(size
);
821 if (size
> log_buf_len
)
822 new_log_buf_len
= size
;
826 early_param("log_buf_len", log_buf_len_setup
);
828 void __init
setup_log_buf(int early
)
834 if (!new_log_buf_len
)
839 memblock_virt_alloc(new_log_buf_len
, PAGE_SIZE
);
841 new_log_buf
= memblock_virt_alloc_nopanic(new_log_buf_len
, 0);
844 if (unlikely(!new_log_buf
)) {
845 pr_err("log_buf_len: %ld bytes not available\n",
850 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
851 log_buf_len
= new_log_buf_len
;
852 log_buf
= new_log_buf
;
854 free
= __LOG_BUF_LEN
- log_next_idx
;
855 memcpy(log_buf
, __log_buf
, __LOG_BUF_LEN
);
856 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
858 pr_info("log_buf_len: %d\n", log_buf_len
);
859 pr_info("early log buf free: %d(%d%%)\n",
860 free
, (free
* 100) / __LOG_BUF_LEN
);
863 static bool __read_mostly ignore_loglevel
;
865 static int __init
ignore_loglevel_setup(char *str
)
868 pr_info("debug: ignoring loglevel setting.\n");
873 early_param("ignore_loglevel", ignore_loglevel_setup
);
874 module_param(ignore_loglevel
, bool, S_IRUGO
| S_IWUSR
);
875 MODULE_PARM_DESC(ignore_loglevel
, "ignore loglevel setting, to"
876 "print all kernel messages to the console.");
878 #ifdef CONFIG_BOOT_PRINTK_DELAY
880 static int boot_delay
; /* msecs delay after each printk during bootup */
881 static unsigned long long loops_per_msec
; /* based on boot_delay */
883 static int __init
boot_delay_setup(char *str
)
887 lpj
= preset_lpj
? preset_lpj
: 1000000; /* some guess */
888 loops_per_msec
= (unsigned long long)lpj
/ 1000 * HZ
;
890 get_option(&str
, &boot_delay
);
891 if (boot_delay
> 10 * 1000)
894 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
895 "HZ: %d, loops_per_msec: %llu\n",
896 boot_delay
, preset_lpj
, lpj
, HZ
, loops_per_msec
);
899 early_param("boot_delay", boot_delay_setup
);
901 static void boot_delay_msec(int level
)
903 unsigned long long k
;
904 unsigned long timeout
;
906 if ((boot_delay
== 0 || system_state
!= SYSTEM_BOOTING
)
907 || (level
>= console_loglevel
&& !ignore_loglevel
)) {
911 k
= (unsigned long long)loops_per_msec
* boot_delay
;
913 timeout
= jiffies
+ msecs_to_jiffies(boot_delay
);
918 * use (volatile) jiffies to prevent
919 * compiler reduction; loop termination via jiffies
920 * is secondary and may or may not happen.
922 if (time_after(jiffies
, timeout
))
924 touch_nmi_watchdog();
928 static inline void boot_delay_msec(int level
)
933 #if defined(CONFIG_PRINTK_TIME)
934 static bool printk_time
= 1;
936 static bool printk_time
;
938 module_param_named(time
, printk_time
, bool, S_IRUGO
| S_IWUSR
);
940 static size_t print_time(u64 ts
, char *buf
)
942 unsigned long rem_nsec
;
947 rem_nsec
= do_div(ts
, 1000000000);
950 return snprintf(NULL
, 0, "[%5lu.000000] ", (unsigned long)ts
);
952 return sprintf(buf
, "[%5lu.%06lu] ",
953 (unsigned long)ts
, rem_nsec
/ 1000);
956 static size_t print_prefix(const struct printk_log
*msg
, bool syslog
, char *buf
)
959 unsigned int prefix
= (msg
->facility
<< 3) | msg
->level
;
963 len
+= sprintf(buf
, "<%u>", prefix
);
968 else if (prefix
> 99)
975 len
+= print_time(msg
->ts_nsec
, buf
? buf
+ len
: NULL
);
979 static size_t msg_print_text(const struct printk_log
*msg
, enum log_flags prev
,
980 bool syslog
, char *buf
, size_t size
)
982 const char *text
= log_text(msg
);
983 size_t text_size
= msg
->text_len
;
988 if ((prev
& LOG_CONT
) && !(msg
->flags
& LOG_PREFIX
))
991 if (msg
->flags
& LOG_CONT
) {
992 if ((prev
& LOG_CONT
) && !(prev
& LOG_NEWLINE
))
995 if (!(msg
->flags
& LOG_NEWLINE
))
1000 const char *next
= memchr(text
, '\n', text_size
);
1004 text_len
= next
- text
;
1006 text_size
-= next
- text
;
1008 text_len
= text_size
;
1012 if (print_prefix(msg
, syslog
, NULL
) +
1013 text_len
+ 1 >= size
- len
)
1017 len
+= print_prefix(msg
, syslog
, buf
+ len
);
1018 memcpy(buf
+ len
, text
, text_len
);
1020 if (next
|| newline
)
1023 /* SYSLOG_ACTION_* buffer size only calculation */
1025 len
+= print_prefix(msg
, syslog
, NULL
);
1027 if (next
|| newline
)
1038 static int syslog_print(char __user
*buf
, int size
)
1041 struct printk_log
*msg
;
1044 text
= kmalloc(LOG_LINE_MAX
+ PREFIX_MAX
, GFP_KERNEL
);
1052 raw_spin_lock_irq(&logbuf_lock
);
1053 if (syslog_seq
< log_first_seq
) {
1054 /* messages are gone, move to first one */
1055 syslog_seq
= log_first_seq
;
1056 syslog_idx
= log_first_idx
;
1060 if (syslog_seq
== log_next_seq
) {
1061 raw_spin_unlock_irq(&logbuf_lock
);
1065 skip
= syslog_partial
;
1066 msg
= log_from_idx(syslog_idx
);
1067 n
= msg_print_text(msg
, syslog_prev
, true, text
,
1068 LOG_LINE_MAX
+ PREFIX_MAX
);
1069 if (n
- syslog_partial
<= size
) {
1070 /* message fits into buffer, move forward */
1071 syslog_idx
= log_next(syslog_idx
);
1073 syslog_prev
= msg
->flags
;
1074 n
-= syslog_partial
;
1077 /* partial read(), remember position */
1079 syslog_partial
+= n
;
1082 raw_spin_unlock_irq(&logbuf_lock
);
1087 if (copy_to_user(buf
, text
+ skip
, n
)) {
1102 static int syslog_print_all(char __user
*buf
, int size
, bool clear
)
1107 text
= kmalloc(LOG_LINE_MAX
+ PREFIX_MAX
, GFP_KERNEL
);
1111 raw_spin_lock_irq(&logbuf_lock
);
1116 enum log_flags prev
;
1118 if (clear_seq
< log_first_seq
) {
1119 /* messages are gone, move to first available one */
1120 clear_seq
= log_first_seq
;
1121 clear_idx
= log_first_idx
;
1125 * Find first record that fits, including all following records,
1126 * into the user-provided buffer for this dump.
1131 while (seq
< log_next_seq
) {
1132 struct printk_log
*msg
= log_from_idx(idx
);
1134 len
+= msg_print_text(msg
, prev
, true, NULL
, 0);
1136 idx
= log_next(idx
);
1140 /* move first record forward until length fits into the buffer */
1144 while (len
> size
&& seq
< log_next_seq
) {
1145 struct printk_log
*msg
= log_from_idx(idx
);
1147 len
-= msg_print_text(msg
, prev
, true, NULL
, 0);
1149 idx
= log_next(idx
);
1153 /* last message fitting into this dump */
1154 next_seq
= log_next_seq
;
1157 while (len
>= 0 && seq
< next_seq
) {
1158 struct printk_log
*msg
= log_from_idx(idx
);
1161 textlen
= msg_print_text(msg
, prev
, true, text
,
1162 LOG_LINE_MAX
+ PREFIX_MAX
);
1167 idx
= log_next(idx
);
1171 raw_spin_unlock_irq(&logbuf_lock
);
1172 if (copy_to_user(buf
+ len
, text
, textlen
))
1176 raw_spin_lock_irq(&logbuf_lock
);
1178 if (seq
< log_first_seq
) {
1179 /* messages are gone, move to next one */
1180 seq
= log_first_seq
;
1181 idx
= log_first_idx
;
1188 clear_seq
= log_next_seq
;
1189 clear_idx
= log_next_idx
;
1191 raw_spin_unlock_irq(&logbuf_lock
);
1197 int do_syslog(int type
, char __user
*buf
, int len
, bool from_file
)
1200 static int saved_console_loglevel
= -1;
1203 error
= check_syslog_permissions(type
, from_file
);
1207 error
= security_syslog(type
);
1212 case SYSLOG_ACTION_CLOSE
: /* Close log */
1214 case SYSLOG_ACTION_OPEN
: /* Open log */
1216 case SYSLOG_ACTION_READ
: /* Read from log */
1218 if (!buf
|| len
< 0)
1223 if (!access_ok(VERIFY_WRITE
, buf
, len
)) {
1227 error
= wait_event_interruptible(log_wait
,
1228 syslog_seq
!= log_next_seq
);
1231 error
= syslog_print(buf
, len
);
1233 /* Read/clear last kernel messages */
1234 case SYSLOG_ACTION_READ_CLEAR
:
1237 /* Read last kernel messages */
1238 case SYSLOG_ACTION_READ_ALL
:
1240 if (!buf
|| len
< 0)
1245 if (!access_ok(VERIFY_WRITE
, buf
, len
)) {
1249 error
= syslog_print_all(buf
, len
, clear
);
1251 /* Clear ring buffer */
1252 case SYSLOG_ACTION_CLEAR
:
1253 syslog_print_all(NULL
, 0, true);
1255 /* Disable logging to console */
1256 case SYSLOG_ACTION_CONSOLE_OFF
:
1257 if (saved_console_loglevel
== -1)
1258 saved_console_loglevel
= console_loglevel
;
1259 console_loglevel
= minimum_console_loglevel
;
1261 /* Enable logging to console */
1262 case SYSLOG_ACTION_CONSOLE_ON
:
1263 if (saved_console_loglevel
!= -1) {
1264 console_loglevel
= saved_console_loglevel
;
1265 saved_console_loglevel
= -1;
1268 /* Set level of messages printed to console */
1269 case SYSLOG_ACTION_CONSOLE_LEVEL
:
1271 if (len
< 1 || len
> 8)
1273 if (len
< minimum_console_loglevel
)
1274 len
= minimum_console_loglevel
;
1275 console_loglevel
= len
;
1276 /* Implicitly re-enable logging to console */
1277 saved_console_loglevel
= -1;
1280 /* Number of chars in the log buffer */
1281 case SYSLOG_ACTION_SIZE_UNREAD
:
1282 raw_spin_lock_irq(&logbuf_lock
);
1283 if (syslog_seq
< log_first_seq
) {
1284 /* messages are gone, move to first one */
1285 syslog_seq
= log_first_seq
;
1286 syslog_idx
= log_first_idx
;
1292 * Short-cut for poll(/"proc/kmsg") which simply checks
1293 * for pending data, not the size; return the count of
1294 * records, not the length.
1296 error
= log_next_idx
- syslog_idx
;
1298 u64 seq
= syslog_seq
;
1299 u32 idx
= syslog_idx
;
1300 enum log_flags prev
= syslog_prev
;
1303 while (seq
< log_next_seq
) {
1304 struct printk_log
*msg
= log_from_idx(idx
);
1306 error
+= msg_print_text(msg
, prev
, true, NULL
, 0);
1307 idx
= log_next(idx
);
1311 error
-= syslog_partial
;
1313 raw_spin_unlock_irq(&logbuf_lock
);
1315 /* Size of the log buffer */
1316 case SYSLOG_ACTION_SIZE_BUFFER
:
1317 error
= log_buf_len
;
1327 SYSCALL_DEFINE3(syslog
, int, type
, char __user
*, buf
, int, len
)
1329 return do_syslog(type
, buf
, len
, SYSLOG_FROM_READER
);
1333 * Call the console drivers, asking them to write out
1334 * log_buf[start] to log_buf[end - 1].
1335 * The console_lock must be held.
1337 static void call_console_drivers(int level
, const char *text
, size_t len
)
1339 struct console
*con
;
1341 trace_console(text
, len
);
1343 if (level
>= console_loglevel
&& !ignore_loglevel
)
1345 if (!console_drivers
)
1348 for_each_console(con
) {
1349 if (exclusive_console
&& con
!= exclusive_console
)
1351 if (!(con
->flags
& CON_ENABLED
))
1355 if (!cpu_online(smp_processor_id()) &&
1356 !(con
->flags
& CON_ANYTIME
))
1358 con
->write(con
, text
, len
);
1363 * Zap console related locks when oopsing. Only zap at most once
1364 * every 10 seconds, to leave time for slow consoles to print a
1367 static void zap_locks(void)
1369 static unsigned long oops_timestamp
;
1371 if (time_after_eq(jiffies
, oops_timestamp
) &&
1372 !time_after(jiffies
, oops_timestamp
+ 30 * HZ
))
1375 oops_timestamp
= jiffies
;
1378 /* If a crash is occurring, make sure we can't deadlock */
1379 raw_spin_lock_init(&logbuf_lock
);
1380 /* And make sure that we print immediately */
1381 sema_init(&console_sem
, 1);
1384 /* Check if we have any console registered that can be called early in boot. */
1385 static int have_callable_console(void)
1387 struct console
*con
;
1389 for_each_console(con
)
1390 if (con
->flags
& CON_ANYTIME
)
1397 * Can we actually use the console at this time on this cpu?
1399 * Console drivers may assume that per-cpu resources have
1400 * been allocated. So unless they're explicitly marked as
1401 * being able to cope (CON_ANYTIME) don't call them until
1402 * this CPU is officially up.
1404 static inline int can_use_console(unsigned int cpu
)
1406 return cpu_online(cpu
) || have_callable_console();
1410 * Try to get console ownership to actually show the kernel
1411 * messages from a 'printk'. Return true (and with the
1412 * console_lock held, and 'console_locked' set) if it
1413 * is successful, false otherwise.
1415 * This gets called with the 'logbuf_lock' spinlock held and
1416 * interrupts disabled. It should return with 'lockbuf_lock'
1417 * released but interrupts still disabled.
1419 static int console_trylock_for_printk(unsigned int cpu
)
1420 __releases(&logbuf_lock
)
1422 int retval
= 0, wake
= 0;
1424 if (console_trylock()) {
1428 * If we can't use the console, we need to release
1429 * the console semaphore by hand to avoid flushing
1430 * the buffer. We need to hold the console semaphore
1431 * in order to do this test safely.
1433 if (!can_use_console(cpu
)) {
1439 logbuf_cpu
= UINT_MAX
;
1440 raw_spin_unlock(&logbuf_lock
);
1446 int printk_delay_msec __read_mostly
;
1448 static inline void printk_delay(void)
1450 if (unlikely(printk_delay_msec
)) {
1451 int m
= printk_delay_msec
;
1455 touch_nmi_watchdog();
1461 * Continuation lines are buffered, and not committed to the record buffer
1462 * until the line is complete, or a race forces it. The line fragments
1463 * though, are printed immediately to the consoles to ensure everything has
1464 * reached the console in case of a kernel crash.
1466 static struct cont
{
1467 char buf
[LOG_LINE_MAX
];
1468 size_t len
; /* length == 0 means unused buffer */
1469 size_t cons
; /* bytes written to console */
1470 struct task_struct
*owner
; /* task of first print*/
1471 u64 ts_nsec
; /* time of first print */
1472 u8 level
; /* log level of first message */
1473 u8 facility
; /* log level of first message */
1474 enum log_flags flags
; /* prefix, newline flags */
1475 bool flushed
:1; /* buffer sealed and committed */
1478 static void cont_flush(enum log_flags flags
)
1487 * If a fragment of this line was directly flushed to the
1488 * console; wait for the console to pick up the rest of the
1489 * line. LOG_NOCONS suppresses a duplicated output.
1491 log_store(cont
.facility
, cont
.level
, flags
| LOG_NOCONS
,
1492 cont
.ts_nsec
, NULL
, 0, cont
.buf
, cont
.len
);
1494 cont
.flushed
= true;
1497 * If no fragment of this line ever reached the console,
1498 * just submit it to the store and free the buffer.
1500 log_store(cont
.facility
, cont
.level
, flags
, 0,
1501 NULL
, 0, cont
.buf
, cont
.len
);
1506 static bool cont_add(int facility
, int level
, const char *text
, size_t len
)
1508 if (cont
.len
&& cont
.flushed
)
1511 if (cont
.len
+ len
> sizeof(cont
.buf
)) {
1512 /* the line gets too long, split it up in separate records */
1513 cont_flush(LOG_CONT
);
1518 cont
.facility
= facility
;
1520 cont
.owner
= current
;
1521 cont
.ts_nsec
= local_clock();
1524 cont
.flushed
= false;
1527 memcpy(cont
.buf
+ cont
.len
, text
, len
);
1530 if (cont
.len
> (sizeof(cont
.buf
) * 80) / 100)
1531 cont_flush(LOG_CONT
);
1536 static size_t cont_print_text(char *text
, size_t size
)
1541 if (cont
.cons
== 0 && (console_prev
& LOG_NEWLINE
)) {
1542 textlen
+= print_time(cont
.ts_nsec
, text
);
1546 len
= cont
.len
- cont
.cons
;
1550 memcpy(text
+ textlen
, cont
.buf
+ cont
.cons
, len
);
1552 cont
.cons
= cont
.len
;
1556 if (cont
.flags
& LOG_NEWLINE
)
1557 text
[textlen
++] = '\n';
1558 /* got everything, release buffer */
1564 asmlinkage
int vprintk_emit(int facility
, int level
,
1565 const char *dict
, size_t dictlen
,
1566 const char *fmt
, va_list args
)
1568 static int recursion_bug
;
1569 static char textbuf
[LOG_LINE_MAX
];
1570 char *text
= textbuf
;
1572 enum log_flags lflags
= 0;
1573 unsigned long flags
;
1575 int printed_len
= 0;
1577 boot_delay_msec(level
);
1580 /* This stops the holder of console_sem just where we want him */
1581 local_irq_save(flags
);
1582 this_cpu
= smp_processor_id();
1585 * Ouch, printk recursed into itself!
1587 if (unlikely(logbuf_cpu
== this_cpu
)) {
1589 * If a crash is occurring during printk() on this CPU,
1590 * then try to get the crash message out but make sure
1591 * we can't deadlock. Otherwise just return to avoid the
1592 * recursion and return - but flag the recursion so that
1593 * it can be printed at the next appropriate moment:
1595 if (!oops_in_progress
&& !lockdep_recursing(current
)) {
1597 goto out_restore_irqs
;
1603 raw_spin_lock(&logbuf_lock
);
1604 logbuf_cpu
= this_cpu
;
1606 if (recursion_bug
) {
1607 static const char recursion_msg
[] =
1608 "BUG: recent printk recursion!";
1611 text_len
= strlen(recursion_msg
);
1612 /* emit KERN_CRIT message */
1613 printed_len
+= log_store(0, 2, LOG_PREFIX
|LOG_NEWLINE
, 0,
1614 NULL
, 0, recursion_msg
, text_len
);
1618 * The printf needs to come first; we need the syslog
1619 * prefix which might be passed-in as a parameter.
1621 text_len
= vscnprintf(text
, sizeof(textbuf
), fmt
, args
);
1623 /* mark and strip a trailing newline */
1624 if (text_len
&& text
[text_len
-1] == '\n') {
1626 lflags
|= LOG_NEWLINE
;
1629 /* strip kernel syslog prefix and extract log level or control flags */
1630 if (facility
== 0) {
1631 int kern_level
= printk_get_level(text
);
1634 const char *end_of_header
= printk_skip_level(text
);
1635 switch (kern_level
) {
1638 level
= kern_level
- '0';
1639 case 'd': /* KERN_DEFAULT */
1640 lflags
|= LOG_PREFIX
;
1643 * No need to check length here because vscnprintf
1644 * put '\0' at the end of the string. Only valid and
1645 * newly printed level is detected.
1647 text_len
-= end_of_header
- text
;
1648 text
= (char *)end_of_header
;
1653 level
= default_message_loglevel
;
1656 lflags
|= LOG_PREFIX
|LOG_NEWLINE
;
1658 if (!(lflags
& LOG_NEWLINE
)) {
1660 * Flush the conflicting buffer. An earlier newline was missing,
1661 * or another task also prints continuation lines.
1663 if (cont
.len
&& (lflags
& LOG_PREFIX
|| cont
.owner
!= current
))
1664 cont_flush(LOG_NEWLINE
);
1666 /* buffer line if possible, otherwise store it right away */
1667 if (cont_add(facility
, level
, text
, text_len
))
1668 printed_len
+= text_len
;
1670 printed_len
+= log_store(facility
, level
,
1671 lflags
| LOG_CONT
, 0,
1672 dict
, dictlen
, text
, text_len
);
1674 bool stored
= false;
1677 * If an earlier newline was missing and it was the same task,
1678 * either merge it with the current buffer and flush, or if
1679 * there was a race with interrupts (prefix == true) then just
1680 * flush it out and store this line separately.
1681 * If the preceding printk was from a different task and missed
1682 * a newline, flush and append the newline.
1685 if (cont
.owner
== current
&& !(lflags
& LOG_PREFIX
))
1686 stored
= cont_add(facility
, level
, text
,
1688 cont_flush(LOG_NEWLINE
);
1692 printed_len
+= text_len
;
1694 printed_len
+= log_store(facility
, level
, lflags
, 0,
1695 dict
, dictlen
, text
, text_len
);
1699 * Try to acquire and then immediately release the console semaphore.
1700 * The release will print out buffers and wake up /dev/kmsg and syslog()
1703 * The console_trylock_for_printk() function will release 'logbuf_lock'
1704 * regardless of whether it actually gets the console semaphore or not.
1706 if (console_trylock_for_printk(this_cpu
))
1711 local_irq_restore(flags
);
1715 EXPORT_SYMBOL(vprintk_emit
);
1717 asmlinkage
int vprintk(const char *fmt
, va_list args
)
1719 return vprintk_emit(0, -1, NULL
, 0, fmt
, args
);
1721 EXPORT_SYMBOL(vprintk
);
1723 asmlinkage
int printk_emit(int facility
, int level
,
1724 const char *dict
, size_t dictlen
,
1725 const char *fmt
, ...)
1730 va_start(args
, fmt
);
1731 r
= vprintk_emit(facility
, level
, dict
, dictlen
, fmt
, args
);
1736 EXPORT_SYMBOL(printk_emit
);
1739 * printk - print a kernel message
1740 * @fmt: format string
1742 * This is printk(). It can be called from any context. We want it to work.
1744 * We try to grab the console_lock. If we succeed, it's easy - we log the
1745 * output and call the console drivers. If we fail to get the semaphore, we
1746 * place the output into the log buffer and return. The current holder of
1747 * the console_sem will notice the new output in console_unlock(); and will
1748 * send it to the consoles before releasing the lock.
1750 * One effect of this deferred printing is that code which calls printk() and
1751 * then changes console_loglevel may break. This is because console_loglevel
1752 * is inspected when the actual printing occurs.
1757 * See the vsnprintf() documentation for format string extensions over C99.
1759 asmlinkage __visible
int printk(const char *fmt
, ...)
1764 #ifdef CONFIG_KGDB_KDB
1765 if (unlikely(kdb_trap_printk
)) {
1766 va_start(args
, fmt
);
1767 r
= vkdb_printf(fmt
, args
);
1772 va_start(args
, fmt
);
1773 r
= vprintk_emit(0, -1, NULL
, 0, fmt
, args
);
1778 EXPORT_SYMBOL(printk
);
1780 #else /* CONFIG_PRINTK */
1782 #define LOG_LINE_MAX 0
1783 #define PREFIX_MAX 0
1784 #define LOG_LINE_MAX 0
1785 static u64 syslog_seq
;
1786 static u32 syslog_idx
;
1787 static u64 console_seq
;
1788 static u32 console_idx
;
1789 static enum log_flags syslog_prev
;
1790 static u64 log_first_seq
;
1791 static u32 log_first_idx
;
1792 static u64 log_next_seq
;
1793 static enum log_flags console_prev
;
1794 static struct cont
{
1800 static struct printk_log
*log_from_idx(u32 idx
) { return NULL
; }
1801 static u32
log_next(u32 idx
) { return 0; }
1802 static void call_console_drivers(int level
, const char *text
, size_t len
) {}
1803 static size_t msg_print_text(const struct printk_log
*msg
, enum log_flags prev
,
1804 bool syslog
, char *buf
, size_t size
) { return 0; }
1805 static size_t cont_print_text(char *text
, size_t size
) { return 0; }
1807 #endif /* CONFIG_PRINTK */
1809 #ifdef CONFIG_EARLY_PRINTK
1810 struct console
*early_console
;
1812 void early_vprintk(const char *fmt
, va_list ap
)
1814 if (early_console
) {
1816 int n
= vscnprintf(buf
, sizeof(buf
), fmt
, ap
);
1818 early_console
->write(early_console
, buf
, n
);
1822 asmlinkage __visible
void early_printk(const char *fmt
, ...)
1827 early_vprintk(fmt
, ap
);
1832 static int __add_preferred_console(char *name
, int idx
, char *options
,
1835 struct console_cmdline
*c
;
1839 * See if this tty is not yet registered, and
1840 * if we have a slot free.
1842 for (i
= 0, c
= console_cmdline
;
1843 i
< MAX_CMDLINECONSOLES
&& c
->name
[0];
1845 if (strcmp(c
->name
, name
) == 0 && c
->index
== idx
) {
1847 selected_console
= i
;
1851 if (i
== MAX_CMDLINECONSOLES
)
1854 selected_console
= i
;
1855 strlcpy(c
->name
, name
, sizeof(c
->name
));
1856 c
->options
= options
;
1857 braille_set_options(c
, brl_options
);
1863 * Set up a list of consoles. Called from init/main.c
1865 static int __init
console_setup(char *str
)
1867 char buf
[sizeof(console_cmdline
[0].name
) + 4]; /* 4 for index */
1868 char *s
, *options
, *brl_options
= NULL
;
1871 if (_braille_console_setup(&str
, &brl_options
))
1875 * Decode str into name, index, options.
1877 if (str
[0] >= '0' && str
[0] <= '9') {
1878 strcpy(buf
, "ttyS");
1879 strncpy(buf
+ 4, str
, sizeof(buf
) - 5);
1881 strncpy(buf
, str
, sizeof(buf
) - 1);
1883 buf
[sizeof(buf
) - 1] = 0;
1884 if ((options
= strchr(str
, ',')) != NULL
)
1887 if (!strcmp(str
, "ttya"))
1888 strcpy(buf
, "ttyS0");
1889 if (!strcmp(str
, "ttyb"))
1890 strcpy(buf
, "ttyS1");
1892 for (s
= buf
; *s
; s
++)
1893 if ((*s
>= '0' && *s
<= '9') || *s
== ',')
1895 idx
= simple_strtoul(s
, NULL
, 10);
1898 __add_preferred_console(buf
, idx
, options
, brl_options
);
1899 console_set_on_cmdline
= 1;
1902 __setup("console=", console_setup
);
1905 * add_preferred_console - add a device to the list of preferred consoles.
1906 * @name: device name
1907 * @idx: device index
1908 * @options: options for this console
1910 * The last preferred console added will be used for kernel messages
1911 * and stdin/out/err for init. Normally this is used by console_setup
1912 * above to handle user-supplied console arguments; however it can also
1913 * be used by arch-specific code either to override the user or more
1914 * commonly to provide a default console (ie from PROM variables) when
1915 * the user has not supplied one.
1917 int add_preferred_console(char *name
, int idx
, char *options
)
1919 return __add_preferred_console(name
, idx
, options
, NULL
);
1922 int update_console_cmdline(char *name
, int idx
, char *name_new
, int idx_new
, char *options
)
1924 struct console_cmdline
*c
;
1927 for (i
= 0, c
= console_cmdline
;
1928 i
< MAX_CMDLINECONSOLES
&& c
->name
[0];
1930 if (strcmp(c
->name
, name
) == 0 && c
->index
== idx
) {
1931 strlcpy(c
->name
, name_new
, sizeof(c
->name
));
1932 c
->name
[sizeof(c
->name
) - 1] = 0;
1933 c
->options
= options
;
1941 bool console_suspend_enabled
= 1;
1942 EXPORT_SYMBOL(console_suspend_enabled
);
1944 static int __init
console_suspend_disable(char *str
)
1946 console_suspend_enabled
= 0;
1949 __setup("no_console_suspend", console_suspend_disable
);
1950 module_param_named(console_suspend
, console_suspend_enabled
,
1951 bool, S_IRUGO
| S_IWUSR
);
1952 MODULE_PARM_DESC(console_suspend
, "suspend console during suspend"
1953 " and hibernate operations");
1956 * suspend_console - suspend the console subsystem
1958 * This disables printk() while we go into suspend states
1960 void suspend_console(void)
1962 if (!console_suspend_enabled
)
1964 printk("Suspending console(s) (use no_console_suspend to debug)\n");
1966 console_suspended
= 1;
1968 mutex_release(&console_lock_dep_map
, 1, _RET_IP_
);
1971 void resume_console(void)
1973 if (!console_suspend_enabled
)
1976 mutex_acquire(&console_lock_dep_map
, 0, 0, _RET_IP_
);
1977 console_suspended
= 0;
1982 * console_cpu_notify - print deferred console messages after CPU hotplug
1983 * @self: notifier struct
1984 * @action: CPU hotplug event
1987 * If printk() is called from a CPU that is not online yet, the messages
1988 * will be spooled but will not show up on the console. This function is
1989 * called when a new CPU comes online (or fails to come up), and ensures
1990 * that any such output gets printed.
1992 static int console_cpu_notify(struct notifier_block
*self
,
1993 unsigned long action
, void *hcpu
)
1998 case CPU_DOWN_FAILED
:
1999 case CPU_UP_CANCELED
:
2007 * console_lock - lock the console system for exclusive use.
2009 * Acquires a lock which guarantees that the caller has
2010 * exclusive access to the console system and the console_drivers list.
2012 * Can sleep, returns nothing.
2014 void console_lock(void)
2019 if (console_suspended
)
2022 console_may_schedule
= 1;
2023 mutex_acquire(&console_lock_dep_map
, 0, 0, _RET_IP_
);
2025 EXPORT_SYMBOL(console_lock
);
2028 * console_trylock - try to lock the console system for exclusive use.
2030 * Tried to acquire a lock which guarantees that the caller has
2031 * exclusive access to the console system and the console_drivers list.
2033 * returns 1 on success, and 0 on failure to acquire the lock.
2035 int console_trylock(void)
2037 if (down_trylock(&console_sem
))
2039 if (console_suspended
) {
2044 console_may_schedule
= 0;
2045 mutex_acquire(&console_lock_dep_map
, 0, 1, _RET_IP_
);
2048 EXPORT_SYMBOL(console_trylock
);
2050 int is_console_locked(void)
2052 return console_locked
;
2055 static void console_cont_flush(char *text
, size_t size
)
2057 unsigned long flags
;
2060 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2066 * We still queue earlier records, likely because the console was
2067 * busy. The earlier ones need to be printed before this one, we
2068 * did not flush any fragment so far, so just let it queue up.
2070 if (console_seq
< log_next_seq
&& !cont
.cons
)
2073 len
= cont_print_text(text
, size
);
2074 raw_spin_unlock(&logbuf_lock
);
2075 stop_critical_timings();
2076 call_console_drivers(cont
.level
, text
, len
);
2077 start_critical_timings();
2078 local_irq_restore(flags
);
2081 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2085 * console_unlock - unlock the console system
2087 * Releases the console_lock which the caller holds on the console system
2088 * and the console driver list.
2090 * While the console_lock was held, console output may have been buffered
2091 * by printk(). If this is the case, console_unlock(); emits
2092 * the output prior to releasing the lock.
2094 * If there is output waiting, we wake /dev/kmsg and syslog() users.
2096 * console_unlock(); may be called from any context.
2098 void console_unlock(void)
2100 static char text
[LOG_LINE_MAX
+ PREFIX_MAX
];
2101 static u64 seen_seq
;
2102 unsigned long flags
;
2103 bool wake_klogd
= false;
2106 if (console_suspended
) {
2111 console_may_schedule
= 0;
2113 /* flush buffered message fragment immediately to console */
2114 console_cont_flush(text
, sizeof(text
));
2117 struct printk_log
*msg
;
2121 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2122 if (seen_seq
!= log_next_seq
) {
2124 seen_seq
= log_next_seq
;
2127 if (console_seq
< log_first_seq
) {
2128 /* messages are gone, move to first one */
2129 console_seq
= log_first_seq
;
2130 console_idx
= log_first_idx
;
2134 if (console_seq
== log_next_seq
)
2137 msg
= log_from_idx(console_idx
);
2138 if (msg
->flags
& LOG_NOCONS
) {
2140 * Skip record we have buffered and already printed
2141 * directly to the console when we received it.
2143 console_idx
= log_next(console_idx
);
2146 * We will get here again when we register a new
2147 * CON_PRINTBUFFER console. Clear the flag so we
2148 * will properly dump everything later.
2150 msg
->flags
&= ~LOG_NOCONS
;
2151 console_prev
= msg
->flags
;
2156 len
= msg_print_text(msg
, console_prev
, false,
2157 text
, sizeof(text
));
2158 console_idx
= log_next(console_idx
);
2160 console_prev
= msg
->flags
;
2161 raw_spin_unlock(&logbuf_lock
);
2163 stop_critical_timings(); /* don't trace print latency */
2164 call_console_drivers(level
, text
, len
);
2165 start_critical_timings();
2166 local_irq_restore(flags
);
2169 mutex_release(&console_lock_dep_map
, 1, _RET_IP_
);
2171 /* Release the exclusive_console once it is used */
2172 if (unlikely(exclusive_console
))
2173 exclusive_console
= NULL
;
2175 raw_spin_unlock(&logbuf_lock
);
2180 * Someone could have filled up the buffer again, so re-check if there's
2181 * something to flush. In case we cannot trylock the console_sem again,
2182 * there's a new owner and the console_unlock() from them will do the
2183 * flush, no worries.
2185 raw_spin_lock(&logbuf_lock
);
2186 retry
= console_seq
!= log_next_seq
;
2187 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2189 if (retry
&& console_trylock())
2195 EXPORT_SYMBOL(console_unlock
);
2198 * console_conditional_schedule - yield the CPU if required
2200 * If the console code is currently allowed to sleep, and
2201 * if this CPU should yield the CPU to another task, do
2204 * Must be called within console_lock();.
2206 void __sched
console_conditional_schedule(void)
2208 if (console_may_schedule
)
2211 EXPORT_SYMBOL(console_conditional_schedule
);
2213 void console_unblank(void)
2218 * console_unblank can no longer be called in interrupt context unless
2219 * oops_in_progress is set to 1..
2221 if (oops_in_progress
) {
2222 if (down_trylock(&console_sem
) != 0)
2228 console_may_schedule
= 0;
2230 if ((c
->flags
& CON_ENABLED
) && c
->unblank
)
2236 * Return the console tty driver structure and its associated index
2238 struct tty_driver
*console_device(int *index
)
2241 struct tty_driver
*driver
= NULL
;
2244 for_each_console(c
) {
2247 driver
= c
->device(c
, index
);
2256 * Prevent further output on the passed console device so that (for example)
2257 * serial drivers can disable console output before suspending a port, and can
2258 * re-enable output afterwards.
2260 void console_stop(struct console
*console
)
2263 console
->flags
&= ~CON_ENABLED
;
2266 EXPORT_SYMBOL(console_stop
);
2268 void console_start(struct console
*console
)
2271 console
->flags
|= CON_ENABLED
;
2274 EXPORT_SYMBOL(console_start
);
2276 static int __read_mostly keep_bootcon
;
2278 static int __init
keep_bootcon_setup(char *str
)
2281 pr_info("debug: skip boot console de-registration.\n");
2286 early_param("keep_bootcon", keep_bootcon_setup
);
2289 * The console driver calls this routine during kernel initialization
2290 * to register the console printing procedure with printk() and to
2291 * print any messages that were printed by the kernel before the
2292 * console driver was initialized.
2294 * This can happen pretty early during the boot process (because of
2295 * early_printk) - sometimes before setup_arch() completes - be careful
2296 * of what kernel features are used - they may not be initialised yet.
2298 * There are two types of consoles - bootconsoles (early_printk) and
2299 * "real" consoles (everything which is not a bootconsole) which are
2300 * handled differently.
2301 * - Any number of bootconsoles can be registered at any time.
2302 * - As soon as a "real" console is registered, all bootconsoles
2303 * will be unregistered automatically.
2304 * - Once a "real" console is registered, any attempt to register a
2305 * bootconsoles will be rejected
2307 void register_console(struct console
*newcon
)
2310 unsigned long flags
;
2311 struct console
*bcon
= NULL
;
2312 struct console_cmdline
*c
;
2314 if (console_drivers
)
2315 for_each_console(bcon
)
2316 if (WARN(bcon
== newcon
,
2317 "console '%s%d' already registered\n",
2318 bcon
->name
, bcon
->index
))
2322 * before we register a new CON_BOOT console, make sure we don't
2323 * already have a valid console
2325 if (console_drivers
&& newcon
->flags
& CON_BOOT
) {
2326 /* find the last or real console */
2327 for_each_console(bcon
) {
2328 if (!(bcon
->flags
& CON_BOOT
)) {
2329 pr_info("Too late to register bootconsole %s%d\n",
2330 newcon
->name
, newcon
->index
);
2336 if (console_drivers
&& console_drivers
->flags
& CON_BOOT
)
2337 bcon
= console_drivers
;
2339 if (preferred_console
< 0 || bcon
|| !console_drivers
)
2340 preferred_console
= selected_console
;
2342 if (newcon
->early_setup
)
2343 newcon
->early_setup();
2346 * See if we want to use this console driver. If we
2347 * didn't select a console we take the first one
2348 * that registers here.
2350 if (preferred_console
< 0) {
2351 if (newcon
->index
< 0)
2353 if (newcon
->setup
== NULL
||
2354 newcon
->setup(newcon
, NULL
) == 0) {
2355 newcon
->flags
|= CON_ENABLED
;
2356 if (newcon
->device
) {
2357 newcon
->flags
|= CON_CONSDEV
;
2358 preferred_console
= 0;
2364 * See if this console matches one we selected on
2367 for (i
= 0, c
= console_cmdline
;
2368 i
< MAX_CMDLINECONSOLES
&& c
->name
[0];
2370 if (strcmp(c
->name
, newcon
->name
) != 0)
2372 if (newcon
->index
>= 0 &&
2373 newcon
->index
!= c
->index
)
2375 if (newcon
->index
< 0)
2376 newcon
->index
= c
->index
;
2378 if (_braille_register_console(newcon
, c
))
2381 if (newcon
->setup
&&
2382 newcon
->setup(newcon
, console_cmdline
[i
].options
) != 0)
2384 newcon
->flags
|= CON_ENABLED
;
2385 newcon
->index
= c
->index
;
2386 if (i
== selected_console
) {
2387 newcon
->flags
|= CON_CONSDEV
;
2388 preferred_console
= selected_console
;
2393 if (!(newcon
->flags
& CON_ENABLED
))
2397 * If we have a bootconsole, and are switching to a real console,
2398 * don't print everything out again, since when the boot console, and
2399 * the real console are the same physical device, it's annoying to
2400 * see the beginning boot messages twice
2402 if (bcon
&& ((newcon
->flags
& (CON_CONSDEV
| CON_BOOT
)) == CON_CONSDEV
))
2403 newcon
->flags
&= ~CON_PRINTBUFFER
;
2406 * Put this console in the list - keep the
2407 * preferred driver at the head of the list.
2410 if ((newcon
->flags
& CON_CONSDEV
) || console_drivers
== NULL
) {
2411 newcon
->next
= console_drivers
;
2412 console_drivers
= newcon
;
2414 newcon
->next
->flags
&= ~CON_CONSDEV
;
2416 newcon
->next
= console_drivers
->next
;
2417 console_drivers
->next
= newcon
;
2419 if (newcon
->flags
& CON_PRINTBUFFER
) {
2421 * console_unlock(); will print out the buffered messages
2424 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2425 console_seq
= syslog_seq
;
2426 console_idx
= syslog_idx
;
2427 console_prev
= syslog_prev
;
2428 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2430 * We're about to replay the log buffer. Only do this to the
2431 * just-registered console to avoid excessive message spam to
2432 * the already-registered consoles.
2434 exclusive_console
= newcon
;
2437 console_sysfs_notify();
2440 * By unregistering the bootconsoles after we enable the real console
2441 * we get the "console xxx enabled" message on all the consoles -
2442 * boot consoles, real consoles, etc - this is to ensure that end
2443 * users know there might be something in the kernel's log buffer that
2444 * went to the bootconsole (that they do not see on the real console)
2446 pr_info("%sconsole [%s%d] enabled\n",
2447 (newcon
->flags
& CON_BOOT
) ? "boot" : "" ,
2448 newcon
->name
, newcon
->index
);
2450 ((newcon
->flags
& (CON_CONSDEV
| CON_BOOT
)) == CON_CONSDEV
) &&
2452 /* We need to iterate through all boot consoles, to make
2453 * sure we print everything out, before we unregister them.
2455 for_each_console(bcon
)
2456 if (bcon
->flags
& CON_BOOT
)
2457 unregister_console(bcon
);
2460 EXPORT_SYMBOL(register_console
);
2462 int unregister_console(struct console
*console
)
2464 struct console
*a
, *b
;
2467 pr_info("%sconsole [%s%d] disabled\n",
2468 (console
->flags
& CON_BOOT
) ? "boot" : "" ,
2469 console
->name
, console
->index
);
2471 res
= _braille_unregister_console(console
);
2477 if (console_drivers
== console
) {
2478 console_drivers
=console
->next
;
2480 } else if (console_drivers
) {
2481 for (a
=console_drivers
->next
, b
=console_drivers
;
2482 a
; b
=a
, a
=b
->next
) {
2492 * If this isn't the last console and it has CON_CONSDEV set, we
2493 * need to set it on the next preferred console.
2495 if (console_drivers
!= NULL
&& console
->flags
& CON_CONSDEV
)
2496 console_drivers
->flags
|= CON_CONSDEV
;
2498 console
->flags
&= ~CON_ENABLED
;
2500 console_sysfs_notify();
2503 EXPORT_SYMBOL(unregister_console
);
2505 static int __init
printk_late_init(void)
2507 struct console
*con
;
2509 for_each_console(con
) {
2510 if (!keep_bootcon
&& con
->flags
& CON_BOOT
) {
2511 unregister_console(con
);
2514 hotcpu_notifier(console_cpu_notify
, 0);
2517 late_initcall(printk_late_init
);
2519 #if defined CONFIG_PRINTK
2521 * Delayed printk version, for scheduler-internal messages:
2523 #define PRINTK_BUF_SIZE 512
2525 #define PRINTK_PENDING_WAKEUP 0x01
2526 #define PRINTK_PENDING_SCHED 0x02
2528 static DEFINE_PER_CPU(int, printk_pending
);
2529 static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE
], printk_sched_buf
);
2531 static void wake_up_klogd_work_func(struct irq_work
*irq_work
)
2533 int pending
= __this_cpu_xchg(printk_pending
, 0);
2535 if (pending
& PRINTK_PENDING_SCHED
) {
2536 char *buf
= __get_cpu_var(printk_sched_buf
);
2537 pr_warn("[sched_delayed] %s", buf
);
2540 if (pending
& PRINTK_PENDING_WAKEUP
)
2541 wake_up_interruptible(&log_wait
);
2544 static DEFINE_PER_CPU(struct irq_work
, wake_up_klogd_work
) = {
2545 .func
= wake_up_klogd_work_func
,
2546 .flags
= IRQ_WORK_LAZY
,
2549 void wake_up_klogd(void)
2552 if (waitqueue_active(&log_wait
)) {
2553 this_cpu_or(printk_pending
, PRINTK_PENDING_WAKEUP
);
2554 irq_work_queue(&__get_cpu_var(wake_up_klogd_work
));
2559 int printk_sched(const char *fmt
, ...)
2561 unsigned long flags
;
2566 local_irq_save(flags
);
2567 buf
= __get_cpu_var(printk_sched_buf
);
2569 va_start(args
, fmt
);
2570 r
= vsnprintf(buf
, PRINTK_BUF_SIZE
, fmt
, args
);
2573 __this_cpu_or(printk_pending
, PRINTK_PENDING_SCHED
);
2574 irq_work_queue(&__get_cpu_var(wake_up_klogd_work
));
2575 local_irq_restore(flags
);
2581 * printk rate limiting, lifted from the networking subsystem.
2583 * This enforces a rate limit: not more than 10 kernel messages
2584 * every 5s to make a denial-of-service attack impossible.
2586 DEFINE_RATELIMIT_STATE(printk_ratelimit_state
, 5 * HZ
, 10);
2588 int __printk_ratelimit(const char *func
)
2590 return ___ratelimit(&printk_ratelimit_state
, func
);
2592 EXPORT_SYMBOL(__printk_ratelimit
);
2595 * printk_timed_ratelimit - caller-controlled printk ratelimiting
2596 * @caller_jiffies: pointer to caller's state
2597 * @interval_msecs: minimum interval between prints
2599 * printk_timed_ratelimit() returns true if more than @interval_msecs
2600 * milliseconds have elapsed since the last time printk_timed_ratelimit()
2603 bool printk_timed_ratelimit(unsigned long *caller_jiffies
,
2604 unsigned int interval_msecs
)
2606 if (*caller_jiffies
== 0
2607 || !time_in_range(jiffies
, *caller_jiffies
,
2609 + msecs_to_jiffies(interval_msecs
))) {
2610 *caller_jiffies
= jiffies
;
2615 EXPORT_SYMBOL(printk_timed_ratelimit
);
2617 static DEFINE_SPINLOCK(dump_list_lock
);
2618 static LIST_HEAD(dump_list
);
2621 * kmsg_dump_register - register a kernel log dumper.
2622 * @dumper: pointer to the kmsg_dumper structure
2624 * Adds a kernel log dumper to the system. The dump callback in the
2625 * structure will be called when the kernel oopses or panics and must be
2626 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
2628 int kmsg_dump_register(struct kmsg_dumper
*dumper
)
2630 unsigned long flags
;
2633 /* The dump callback needs to be set */
2637 spin_lock_irqsave(&dump_list_lock
, flags
);
2638 /* Don't allow registering multiple times */
2639 if (!dumper
->registered
) {
2640 dumper
->registered
= 1;
2641 list_add_tail_rcu(&dumper
->list
, &dump_list
);
2644 spin_unlock_irqrestore(&dump_list_lock
, flags
);
2648 EXPORT_SYMBOL_GPL(kmsg_dump_register
);
2651 * kmsg_dump_unregister - unregister a kmsg dumper.
2652 * @dumper: pointer to the kmsg_dumper structure
2654 * Removes a dump device from the system. Returns zero on success and
2655 * %-EINVAL otherwise.
2657 int kmsg_dump_unregister(struct kmsg_dumper
*dumper
)
2659 unsigned long flags
;
2662 spin_lock_irqsave(&dump_list_lock
, flags
);
2663 if (dumper
->registered
) {
2664 dumper
->registered
= 0;
2665 list_del_rcu(&dumper
->list
);
2668 spin_unlock_irqrestore(&dump_list_lock
, flags
);
2673 EXPORT_SYMBOL_GPL(kmsg_dump_unregister
);
2675 static bool always_kmsg_dump
;
2676 module_param_named(always_kmsg_dump
, always_kmsg_dump
, bool, S_IRUGO
| S_IWUSR
);
2679 * kmsg_dump - dump kernel log to kernel message dumpers.
2680 * @reason: the reason (oops, panic etc) for dumping
2682 * Call each of the registered dumper's dump() callback, which can
2683 * retrieve the kmsg records with kmsg_dump_get_line() or
2684 * kmsg_dump_get_buffer().
2686 void kmsg_dump(enum kmsg_dump_reason reason
)
2688 struct kmsg_dumper
*dumper
;
2689 unsigned long flags
;
2691 if ((reason
> KMSG_DUMP_OOPS
) && !always_kmsg_dump
)
2695 list_for_each_entry_rcu(dumper
, &dump_list
, list
) {
2696 if (dumper
->max_reason
&& reason
> dumper
->max_reason
)
2699 /* initialize iterator with data about the stored records */
2700 dumper
->active
= true;
2702 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2703 dumper
->cur_seq
= clear_seq
;
2704 dumper
->cur_idx
= clear_idx
;
2705 dumper
->next_seq
= log_next_seq
;
2706 dumper
->next_idx
= log_next_idx
;
2707 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2709 /* invoke dumper which will iterate over records */
2710 dumper
->dump(dumper
, reason
);
2712 /* reset iterator */
2713 dumper
->active
= false;
2719 * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
2720 * @dumper: registered kmsg dumper
2721 * @syslog: include the "<4>" prefixes
2722 * @line: buffer to copy the line to
2723 * @size: maximum size of the buffer
2724 * @len: length of line placed into buffer
2726 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2727 * record, and copy one record into the provided buffer.
2729 * Consecutive calls will return the next available record moving
2730 * towards the end of the buffer with the youngest messages.
2732 * A return value of FALSE indicates that there are no more records to
2735 * The function is similar to kmsg_dump_get_line(), but grabs no locks.
2737 bool kmsg_dump_get_line_nolock(struct kmsg_dumper
*dumper
, bool syslog
,
2738 char *line
, size_t size
, size_t *len
)
2740 struct printk_log
*msg
;
2744 if (!dumper
->active
)
2747 if (dumper
->cur_seq
< log_first_seq
) {
2748 /* messages are gone, move to first available one */
2749 dumper
->cur_seq
= log_first_seq
;
2750 dumper
->cur_idx
= log_first_idx
;
2754 if (dumper
->cur_seq
>= log_next_seq
)
2757 msg
= log_from_idx(dumper
->cur_idx
);
2758 l
= msg_print_text(msg
, 0, syslog
, line
, size
);
2760 dumper
->cur_idx
= log_next(dumper
->cur_idx
);
2770 * kmsg_dump_get_line - retrieve one kmsg log line
2771 * @dumper: registered kmsg dumper
2772 * @syslog: include the "<4>" prefixes
2773 * @line: buffer to copy the line to
2774 * @size: maximum size of the buffer
2775 * @len: length of line placed into buffer
2777 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2778 * record, and copy one record into the provided buffer.
2780 * Consecutive calls will return the next available record moving
2781 * towards the end of the buffer with the youngest messages.
2783 * A return value of FALSE indicates that there are no more records to
2786 bool kmsg_dump_get_line(struct kmsg_dumper
*dumper
, bool syslog
,
2787 char *line
, size_t size
, size_t *len
)
2789 unsigned long flags
;
2792 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2793 ret
= kmsg_dump_get_line_nolock(dumper
, syslog
, line
, size
, len
);
2794 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2798 EXPORT_SYMBOL_GPL(kmsg_dump_get_line
);
2801 * kmsg_dump_get_buffer - copy kmsg log lines
2802 * @dumper: registered kmsg dumper
2803 * @syslog: include the "<4>" prefixes
2804 * @buf: buffer to copy the line to
2805 * @size: maximum size of the buffer
2806 * @len: length of line placed into buffer
2808 * Start at the end of the kmsg buffer and fill the provided buffer
2809 * with as many of the the *youngest* kmsg records that fit into it.
2810 * If the buffer is large enough, all available kmsg records will be
2811 * copied with a single call.
2813 * Consecutive calls will fill the buffer with the next block of
2814 * available older records, not including the earlier retrieved ones.
2816 * A return value of FALSE indicates that there are no more records to
2819 bool kmsg_dump_get_buffer(struct kmsg_dumper
*dumper
, bool syslog
,
2820 char *buf
, size_t size
, size_t *len
)
2822 unsigned long flags
;
2827 enum log_flags prev
;
2831 if (!dumper
->active
)
2834 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2835 if (dumper
->cur_seq
< log_first_seq
) {
2836 /* messages are gone, move to first available one */
2837 dumper
->cur_seq
= log_first_seq
;
2838 dumper
->cur_idx
= log_first_idx
;
2842 if (dumper
->cur_seq
>= dumper
->next_seq
) {
2843 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2847 /* calculate length of entire buffer */
2848 seq
= dumper
->cur_seq
;
2849 idx
= dumper
->cur_idx
;
2851 while (seq
< dumper
->next_seq
) {
2852 struct printk_log
*msg
= log_from_idx(idx
);
2854 l
+= msg_print_text(msg
, prev
, true, NULL
, 0);
2855 idx
= log_next(idx
);
2860 /* move first record forward until length fits into the buffer */
2861 seq
= dumper
->cur_seq
;
2862 idx
= dumper
->cur_idx
;
2864 while (l
> size
&& seq
< dumper
->next_seq
) {
2865 struct printk_log
*msg
= log_from_idx(idx
);
2867 l
-= msg_print_text(msg
, prev
, true, NULL
, 0);
2868 idx
= log_next(idx
);
2873 /* last message in next interation */
2878 while (seq
< dumper
->next_seq
) {
2879 struct printk_log
*msg
= log_from_idx(idx
);
2881 l
+= msg_print_text(msg
, prev
, syslog
, buf
+ l
, size
- l
);
2882 idx
= log_next(idx
);
2887 dumper
->next_seq
= next_seq
;
2888 dumper
->next_idx
= next_idx
;
2890 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2896 EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer
);
2899 * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
2900 * @dumper: registered kmsg dumper
2902 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2903 * kmsg_dump_get_buffer() can be called again and used multiple
2904 * times within the same dumper.dump() callback.
2906 * The function is similar to kmsg_dump_rewind(), but grabs no locks.
2908 void kmsg_dump_rewind_nolock(struct kmsg_dumper
*dumper
)
2910 dumper
->cur_seq
= clear_seq
;
2911 dumper
->cur_idx
= clear_idx
;
2912 dumper
->next_seq
= log_next_seq
;
2913 dumper
->next_idx
= log_next_idx
;
2917 * kmsg_dump_rewind - reset the interator
2918 * @dumper: registered kmsg dumper
2920 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2921 * kmsg_dump_get_buffer() can be called again and used multiple
2922 * times within the same dumper.dump() callback.
2924 void kmsg_dump_rewind(struct kmsg_dumper
*dumper
)
2926 unsigned long flags
;
2928 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2929 kmsg_dump_rewind_nolock(dumper
);
2930 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2932 EXPORT_SYMBOL_GPL(kmsg_dump_rewind
);
2934 static char dump_stack_arch_desc_str
[128];
2937 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
2938 * @fmt: printf-style format string
2939 * @...: arguments for the format string
2941 * The configured string will be printed right after utsname during task
2942 * dumps. Usually used to add arch-specific system identifiers. If an
2943 * arch wants to make use of such an ID string, it should initialize this
2944 * as soon as possible during boot.
2946 void __init
dump_stack_set_arch_desc(const char *fmt
, ...)
2950 va_start(args
, fmt
);
2951 vsnprintf(dump_stack_arch_desc_str
, sizeof(dump_stack_arch_desc_str
),
2957 * dump_stack_print_info - print generic debug info for dump_stack()
2958 * @log_lvl: log level
2960 * Arch-specific dump_stack() implementations can use this function to
2961 * print out the same debug information as the generic dump_stack().
2963 void dump_stack_print_info(const char *log_lvl
)
2965 printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
2966 log_lvl
, raw_smp_processor_id(), current
->pid
, current
->comm
,
2967 print_tainted(), init_utsname()->release
,
2968 (int)strcspn(init_utsname()->version
, " "),
2969 init_utsname()->version
);
2971 if (dump_stack_arch_desc_str
[0] != '\0')
2972 printk("%sHardware name: %s\n",
2973 log_lvl
, dump_stack_arch_desc_str
);
2975 print_worker_info(log_lvl
, current
);
2979 * show_regs_print_info - print generic debug info for show_regs()
2980 * @log_lvl: log level
2982 * show_regs() implementations can use this function to print out generic
2983 * debug information.
2985 void show_regs_print_info(const char *log_lvl
)
2987 dump_stack_print_info(log_lvl
);
2989 printk("%stask: %p ti: %p task.ti: %p\n",
2990 log_lvl
, current
, current_thread_info(),
2991 task_thread_info(current
));