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 int console_printk
[4] = {
58 CONSOLE_LOGLEVEL_DEFAULT
, /* console_loglevel */
59 MESSAGE_LOGLEVEL_DEFAULT
, /* default_message_loglevel */
60 CONSOLE_LOGLEVEL_MIN
, /* minimum_console_loglevel */
61 CONSOLE_LOGLEVEL_DEFAULT
, /* default_console_loglevel */
64 /* Deferred messaged from sched code are marked by this special level */
65 #define SCHED_MESSAGE_LOGLEVEL -2
68 * Low level drivers may need that to know if they can schedule in
69 * their unblank() callback or not. So let's export it.
72 EXPORT_SYMBOL(oops_in_progress
);
75 * console_sem protects the console_drivers list, and also
76 * provides serialisation for access to the entire console
79 static DEFINE_SEMAPHORE(console_sem
);
80 struct console
*console_drivers
;
81 EXPORT_SYMBOL_GPL(console_drivers
);
84 static struct lockdep_map console_lock_dep_map
= {
85 .name
= "console_lock"
90 * Helper macros to handle lockdep when locking/unlocking console_sem. We use
91 * macros instead of functions so that _RET_IP_ contains useful information.
93 #define down_console_sem() do { \
95 mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\
98 static int __down_trylock_console_sem(unsigned long ip
)
100 if (down_trylock(&console_sem
))
102 mutex_acquire(&console_lock_dep_map
, 0, 1, ip
);
105 #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_)
107 #define up_console_sem() do { \
108 mutex_release(&console_lock_dep_map, 1, _RET_IP_);\
113 * This is used for debugging the mess that is the VT code by
114 * keeping track if we have the console semaphore held. It's
115 * definitely not the perfect debug tool (we don't know if _WE_
116 * hold it and are racing, but it helps tracking those weird code
117 * paths in the console code where we end up in places I want
118 * locked without the console sempahore held).
120 static int console_locked
, console_suspended
;
123 * If exclusive_console is non-NULL then only this console is to be printed to.
125 static struct console
*exclusive_console
;
128 * Array of consoles built from command line options (console=)
131 #define MAX_CMDLINECONSOLES 8
133 static struct console_cmdline console_cmdline
[MAX_CMDLINECONSOLES
];
135 static int selected_console
= -1;
136 static int preferred_console
= -1;
137 int console_set_on_cmdline
;
138 EXPORT_SYMBOL(console_set_on_cmdline
);
140 /* Flag: console code may call schedule() */
141 static int console_may_schedule
;
144 * The printk log buffer consists of a chain of concatenated variable
145 * length records. Every record starts with a record header, containing
146 * the overall length of the record.
148 * The heads to the first and last entry in the buffer, as well as the
149 * sequence numbers of these entries are maintained when messages are
152 * If the heads indicate available messages, the length in the header
153 * tells the start next message. A length == 0 for the next message
154 * indicates a wrap-around to the beginning of the buffer.
156 * Every record carries the monotonic timestamp in microseconds, as well as
157 * the standard userspace syslog level and syslog facility. The usual
158 * kernel messages use LOG_KERN; userspace-injected messages always carry
159 * a matching syslog facility, by default LOG_USER. The origin of every
160 * message can be reliably determined that way.
162 * The human readable log message directly follows the message header. The
163 * length of the message text is stored in the header, the stored message
166 * Optionally, a message can carry a dictionary of properties (key/value pairs),
167 * to provide userspace with a machine-readable message context.
169 * Examples for well-defined, commonly used property names are:
170 * DEVICE=b12:8 device identifier
174 * +sound:card0 subsystem:devname
175 * SUBSYSTEM=pci driver-core subsystem name
177 * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
178 * follows directly after a '=' character. Every property is terminated by
179 * a '\0' character. The last property is not terminated.
181 * Example of a message structure:
182 * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec
183 * 0008 34 00 record is 52 bytes long
184 * 000a 0b 00 text is 11 bytes long
185 * 000c 1f 00 dictionary is 23 bytes long
186 * 000e 03 00 LOG_KERN (facility) LOG_ERR (level)
187 * 0010 69 74 27 73 20 61 20 6c "it's a l"
189 * 001b 44 45 56 49 43 "DEVIC"
190 * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D"
191 * 52 49 56 45 52 3d 62 75 "RIVER=bu"
193 * 0032 00 00 00 padding to next message header
195 * The 'struct printk_log' buffer header must never be directly exported to
196 * userspace, it is a kernel-private implementation detail that might
197 * need to be changed in the future, when the requirements change.
199 * /dev/kmsg exports the structured data in the following line format:
200 * "level,sequnum,timestamp;<message text>\n"
202 * The optional key/value pairs are attached as continuation lines starting
203 * with a space character and terminated by a newline. All possible
204 * non-prinatable characters are escaped in the "\xff" notation.
206 * Users of the export format should ignore possible additional values
207 * separated by ',', and find the message after the ';' character.
211 LOG_NOCONS
= 1, /* already flushed, do not print to console */
212 LOG_NEWLINE
= 2, /* text ended with a newline */
213 LOG_PREFIX
= 4, /* text started with a prefix */
214 LOG_CONT
= 8, /* text is a fragment of a continuation line */
218 u64 ts_nsec
; /* timestamp in nanoseconds */
219 u16 len
; /* length of entire record */
220 u16 text_len
; /* length of text buffer */
221 u16 dict_len
; /* length of dictionary buffer */
222 u8 facility
; /* syslog facility */
223 u8 flags
:5; /* internal record flags */
224 u8 level
:3; /* syslog level */
228 * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken
229 * within the scheduler's rq lock. It must be released before calling
230 * console_unlock() or anything else that might wake up a process.
232 static DEFINE_RAW_SPINLOCK(logbuf_lock
);
235 DECLARE_WAIT_QUEUE_HEAD(log_wait
);
236 /* the next printk record to read by syslog(READ) or /proc/kmsg */
237 static u64 syslog_seq
;
238 static u32 syslog_idx
;
239 static enum log_flags syslog_prev
;
240 static size_t syslog_partial
;
242 /* index and sequence number of the first record stored in the buffer */
243 static u64 log_first_seq
;
244 static u32 log_first_idx
;
246 /* index and sequence number of the next record to store in the buffer */
247 static u64 log_next_seq
;
248 static u32 log_next_idx
;
250 /* the next printk record to write to the console */
251 static u64 console_seq
;
252 static u32 console_idx
;
253 static enum log_flags console_prev
;
255 /* the next printk record to read after the last 'clear' command */
256 static u64 clear_seq
;
257 static u32 clear_idx
;
259 #define PREFIX_MAX 32
260 #define LOG_LINE_MAX 1024 - PREFIX_MAX
263 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
266 #define LOG_ALIGN __alignof__(struct printk_log)
268 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
269 #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT)
270 static char __log_buf
[__LOG_BUF_LEN
] __aligned(LOG_ALIGN
);
271 static char *log_buf
= __log_buf
;
272 static u32 log_buf_len
= __LOG_BUF_LEN
;
274 /* human readable text of the record */
275 static char *log_text(const struct printk_log
*msg
)
277 return (char *)msg
+ sizeof(struct printk_log
);
280 /* optional key/value pair dictionary attached to the record */
281 static char *log_dict(const struct printk_log
*msg
)
283 return (char *)msg
+ sizeof(struct printk_log
) + msg
->text_len
;
286 /* get record by index; idx must point to valid msg */
287 static struct printk_log
*log_from_idx(u32 idx
)
289 struct printk_log
*msg
= (struct printk_log
*)(log_buf
+ idx
);
292 * A length == 0 record is the end of buffer marker. Wrap around and
293 * read the message at the start of the buffer.
296 return (struct printk_log
*)log_buf
;
300 /* get next record; idx must point to valid msg */
301 static u32
log_next(u32 idx
)
303 struct printk_log
*msg
= (struct printk_log
*)(log_buf
+ idx
);
305 /* length == 0 indicates the end of the buffer; wrap */
307 * A length == 0 record is the end of buffer marker. Wrap around and
308 * read the message at the start of the buffer as *this* one, and
309 * return the one after that.
312 msg
= (struct printk_log
*)log_buf
;
315 return idx
+ msg
->len
;
319 * Check whether there is enough free space for the given message.
321 * The same values of first_idx and next_idx mean that the buffer
322 * is either empty or full.
324 * If the buffer is empty, we must respect the position of the indexes.
325 * They cannot be reset to the beginning of the buffer.
327 static int logbuf_has_space(u32 msg_size
, bool empty
)
331 if (log_next_idx
> log_first_idx
|| empty
)
332 free
= max(log_buf_len
- log_next_idx
, log_first_idx
);
334 free
= log_first_idx
- log_next_idx
;
337 * We need space also for an empty header that signalizes wrapping
340 return free
>= msg_size
+ sizeof(struct printk_log
);
343 static int log_make_free_space(u32 msg_size
)
345 while (log_first_seq
< log_next_seq
) {
346 if (logbuf_has_space(msg_size
, false))
348 /* drop old messages until we have enough contiguous space */
349 log_first_idx
= log_next(log_first_idx
);
353 /* sequence numbers are equal, so the log buffer is empty */
354 if (logbuf_has_space(msg_size
, true))
360 /* compute the message size including the padding bytes */
361 static u32
msg_used_size(u16 text_len
, u16 dict_len
, u32
*pad_len
)
365 size
= sizeof(struct printk_log
) + text_len
+ dict_len
;
366 *pad_len
= (-size
) & (LOG_ALIGN
- 1);
373 * Define how much of the log buffer we could take at maximum. The value
374 * must be greater than two. Note that only half of the buffer is available
375 * when the index points to the middle.
377 #define MAX_LOG_TAKE_PART 4
378 static const char trunc_msg
[] = "<truncated>";
380 static u32
truncate_msg(u16
*text_len
, u16
*trunc_msg_len
,
381 u16
*dict_len
, u32
*pad_len
)
384 * The message should not take the whole buffer. Otherwise, it might
385 * get removed too soon.
387 u32 max_text_len
= log_buf_len
/ MAX_LOG_TAKE_PART
;
388 if (*text_len
> max_text_len
)
389 *text_len
= max_text_len
;
390 /* enable the warning message */
391 *trunc_msg_len
= strlen(trunc_msg
);
392 /* disable the "dict" completely */
394 /* compute the size again, count also the warning message */
395 return msg_used_size(*text_len
+ *trunc_msg_len
, 0, pad_len
);
398 /* insert record into the buffer, discard old ones, update heads */
399 static int log_store(int facility
, int level
,
400 enum log_flags flags
, u64 ts_nsec
,
401 const char *dict
, u16 dict_len
,
402 const char *text
, u16 text_len
)
404 struct printk_log
*msg
;
406 u16 trunc_msg_len
= 0;
408 /* number of '\0' padding bytes to next message */
409 size
= msg_used_size(text_len
, dict_len
, &pad_len
);
411 if (log_make_free_space(size
)) {
412 /* truncate the message if it is too long for empty buffer */
413 size
= truncate_msg(&text_len
, &trunc_msg_len
,
414 &dict_len
, &pad_len
);
415 /* survive when the log buffer is too small for trunc_msg */
416 if (log_make_free_space(size
))
420 if (log_next_idx
+ size
+ sizeof(struct printk_log
) > log_buf_len
) {
422 * This message + an additional empty header does not fit
423 * at the end of the buffer. Add an empty header with len == 0
424 * to signify a wrap around.
426 memset(log_buf
+ log_next_idx
, 0, sizeof(struct printk_log
));
431 msg
= (struct printk_log
*)(log_buf
+ log_next_idx
);
432 memcpy(log_text(msg
), text
, text_len
);
433 msg
->text_len
= text_len
;
435 memcpy(log_text(msg
) + text_len
, trunc_msg
, trunc_msg_len
);
436 msg
->text_len
+= trunc_msg_len
;
438 memcpy(log_dict(msg
), dict
, dict_len
);
439 msg
->dict_len
= dict_len
;
440 msg
->facility
= facility
;
441 msg
->level
= level
& 7;
442 msg
->flags
= flags
& 0x1f;
444 msg
->ts_nsec
= ts_nsec
;
446 msg
->ts_nsec
= local_clock();
447 memset(log_dict(msg
) + dict_len
, 0, pad_len
);
451 log_next_idx
+= msg
->len
;
454 return msg
->text_len
;
457 int dmesg_restrict
= IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT
);
459 static int syslog_action_restricted(int type
)
464 * Unless restricted, we allow "read all" and "get buffer size"
467 return type
!= SYSLOG_ACTION_READ_ALL
&&
468 type
!= SYSLOG_ACTION_SIZE_BUFFER
;
471 static int check_syslog_permissions(int type
, bool from_file
)
474 * If this is from /proc/kmsg and we've already opened it, then we've
475 * already done the capabilities checks at open time.
477 if (from_file
&& type
!= SYSLOG_ACTION_OPEN
)
480 if (syslog_action_restricted(type
)) {
481 if (capable(CAP_SYSLOG
))
484 * For historical reasons, accept CAP_SYS_ADMIN too, with
487 if (capable(CAP_SYS_ADMIN
)) {
488 pr_warn_once("%s (%d): Attempt to access syslog with "
489 "CAP_SYS_ADMIN but no CAP_SYSLOG "
491 current
->comm
, task_pid_nr(current
));
496 return security_syslog(type
);
500 /* /dev/kmsg - userspace message inject/listen interface */
501 struct devkmsg_user
{
509 static ssize_t
devkmsg_writev(struct kiocb
*iocb
, const struct iovec
*iv
,
510 unsigned long count
, loff_t pos
)
514 int level
= default_message_loglevel
;
515 int facility
= 1; /* LOG_USER */
516 size_t len
= iov_length(iv
, count
);
519 if (len
> LOG_LINE_MAX
)
521 buf
= kmalloc(len
+1, GFP_KERNEL
);
526 for (i
= 0; i
< count
; i
++) {
527 if (copy_from_user(line
, iv
[i
].iov_base
, iv
[i
].iov_len
)) {
531 line
+= iv
[i
].iov_len
;
535 * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
536 * the decimal value represents 32bit, the lower 3 bit are the log
537 * level, the rest are the log facility.
539 * If no prefix or no userspace facility is specified, we
540 * enforce LOG_USER, to be able to reliably distinguish
541 * kernel-generated messages from userspace-injected ones.
544 if (line
[0] == '<') {
547 i
= simple_strtoul(line
+1, &endp
, 10);
548 if (endp
&& endp
[0] == '>') {
559 printk_emit(facility
, level
, NULL
, 0, "%s", line
);
565 static ssize_t
devkmsg_read(struct file
*file
, char __user
*buf
,
566 size_t count
, loff_t
*ppos
)
568 struct devkmsg_user
*user
= file
->private_data
;
569 struct printk_log
*msg
;
579 ret
= mutex_lock_interruptible(&user
->lock
);
582 raw_spin_lock_irq(&logbuf_lock
);
583 while (user
->seq
== log_next_seq
) {
584 if (file
->f_flags
& O_NONBLOCK
) {
586 raw_spin_unlock_irq(&logbuf_lock
);
590 raw_spin_unlock_irq(&logbuf_lock
);
591 ret
= wait_event_interruptible(log_wait
,
592 user
->seq
!= log_next_seq
);
595 raw_spin_lock_irq(&logbuf_lock
);
598 if (user
->seq
< log_first_seq
) {
599 /* our last seen message is gone, return error and reset */
600 user
->idx
= log_first_idx
;
601 user
->seq
= log_first_seq
;
603 raw_spin_unlock_irq(&logbuf_lock
);
607 msg
= log_from_idx(user
->idx
);
608 ts_usec
= msg
->ts_nsec
;
609 do_div(ts_usec
, 1000);
612 * If we couldn't merge continuation line fragments during the print,
613 * export the stored flags to allow an optional external merge of the
614 * records. Merging the records isn't always neccessarily correct, like
615 * when we hit a race during printing. In most cases though, it produces
616 * better readable output. 'c' in the record flags mark the first
617 * fragment of a line, '+' the following.
619 if (msg
->flags
& LOG_CONT
&& !(user
->prev
& LOG_CONT
))
621 else if ((msg
->flags
& LOG_CONT
) ||
622 ((user
->prev
& LOG_CONT
) && !(msg
->flags
& LOG_PREFIX
)))
625 len
= sprintf(user
->buf
, "%u,%llu,%llu,%c;",
626 (msg
->facility
<< 3) | msg
->level
,
627 user
->seq
, ts_usec
, cont
);
628 user
->prev
= msg
->flags
;
630 /* escape non-printable characters */
631 for (i
= 0; i
< msg
->text_len
; i
++) {
632 unsigned char c
= log_text(msg
)[i
];
634 if (c
< ' ' || c
>= 127 || c
== '\\')
635 len
+= sprintf(user
->buf
+ len
, "\\x%02x", c
);
637 user
->buf
[len
++] = c
;
639 user
->buf
[len
++] = '\n';
644 for (i
= 0; i
< msg
->dict_len
; i
++) {
645 unsigned char c
= log_dict(msg
)[i
];
648 user
->buf
[len
++] = ' ';
653 user
->buf
[len
++] = '\n';
658 if (c
< ' ' || c
>= 127 || c
== '\\') {
659 len
+= sprintf(user
->buf
+ len
, "\\x%02x", c
);
663 user
->buf
[len
++] = c
;
665 user
->buf
[len
++] = '\n';
668 user
->idx
= log_next(user
->idx
);
670 raw_spin_unlock_irq(&logbuf_lock
);
677 if (copy_to_user(buf
, user
->buf
, len
)) {
683 mutex_unlock(&user
->lock
);
687 static loff_t
devkmsg_llseek(struct file
*file
, loff_t offset
, int whence
)
689 struct devkmsg_user
*user
= file
->private_data
;
697 raw_spin_lock_irq(&logbuf_lock
);
700 /* the first record */
701 user
->idx
= log_first_idx
;
702 user
->seq
= log_first_seq
;
706 * The first record after the last SYSLOG_ACTION_CLEAR,
707 * like issued by 'dmesg -c'. Reading /dev/kmsg itself
708 * changes no global state, and does not clear anything.
710 user
->idx
= clear_idx
;
711 user
->seq
= clear_seq
;
714 /* after the last record */
715 user
->idx
= log_next_idx
;
716 user
->seq
= log_next_seq
;
721 raw_spin_unlock_irq(&logbuf_lock
);
725 static unsigned int devkmsg_poll(struct file
*file
, poll_table
*wait
)
727 struct devkmsg_user
*user
= file
->private_data
;
731 return POLLERR
|POLLNVAL
;
733 poll_wait(file
, &log_wait
, wait
);
735 raw_spin_lock_irq(&logbuf_lock
);
736 if (user
->seq
< log_next_seq
) {
737 /* return error when data has vanished underneath us */
738 if (user
->seq
< log_first_seq
)
739 ret
= POLLIN
|POLLRDNORM
|POLLERR
|POLLPRI
;
741 ret
= POLLIN
|POLLRDNORM
;
743 raw_spin_unlock_irq(&logbuf_lock
);
748 static int devkmsg_open(struct inode
*inode
, struct file
*file
)
750 struct devkmsg_user
*user
;
753 /* write-only does not need any file context */
754 if ((file
->f_flags
& O_ACCMODE
) == O_WRONLY
)
757 err
= check_syslog_permissions(SYSLOG_ACTION_READ_ALL
,
762 user
= kmalloc(sizeof(struct devkmsg_user
), GFP_KERNEL
);
766 mutex_init(&user
->lock
);
768 raw_spin_lock_irq(&logbuf_lock
);
769 user
->idx
= log_first_idx
;
770 user
->seq
= log_first_seq
;
771 raw_spin_unlock_irq(&logbuf_lock
);
773 file
->private_data
= user
;
777 static int devkmsg_release(struct inode
*inode
, struct file
*file
)
779 struct devkmsg_user
*user
= file
->private_data
;
784 mutex_destroy(&user
->lock
);
789 const struct file_operations kmsg_fops
= {
790 .open
= devkmsg_open
,
791 .read
= devkmsg_read
,
792 .aio_write
= devkmsg_writev
,
793 .llseek
= devkmsg_llseek
,
794 .poll
= devkmsg_poll
,
795 .release
= devkmsg_release
,
800 * This appends the listed symbols to /proc/vmcore
802 * /proc/vmcore is used by various utilities, like crash and makedumpfile to
803 * obtain access to symbols that are otherwise very difficult to locate. These
804 * symbols are specifically used so that utilities can access and extract the
805 * dmesg log from a vmcore file after a crash.
807 void log_buf_kexec_setup(void)
809 VMCOREINFO_SYMBOL(log_buf
);
810 VMCOREINFO_SYMBOL(log_buf_len
);
811 VMCOREINFO_SYMBOL(log_first_idx
);
812 VMCOREINFO_SYMBOL(log_next_idx
);
814 * Export struct printk_log size and field offsets. User space tools can
815 * parse it and detect any changes to structure down the line.
817 VMCOREINFO_STRUCT_SIZE(printk_log
);
818 VMCOREINFO_OFFSET(printk_log
, ts_nsec
);
819 VMCOREINFO_OFFSET(printk_log
, len
);
820 VMCOREINFO_OFFSET(printk_log
, text_len
);
821 VMCOREINFO_OFFSET(printk_log
, dict_len
);
825 /* requested log_buf_len from kernel cmdline */
826 static unsigned long __initdata new_log_buf_len
;
828 /* we practice scaling the ring buffer by powers of 2 */
829 static void __init
log_buf_len_update(unsigned size
)
832 size
= roundup_pow_of_two(size
);
833 if (size
> log_buf_len
)
834 new_log_buf_len
= size
;
837 /* save requested log_buf_len since it's too early to process it */
838 static int __init
log_buf_len_setup(char *str
)
840 unsigned size
= memparse(str
, &str
);
842 log_buf_len_update(size
);
846 early_param("log_buf_len", log_buf_len_setup
);
848 static void __init
log_buf_add_cpu(void)
850 unsigned int cpu_extra
;
853 * archs should set up cpu_possible_bits properly with
854 * set_cpu_possible() after setup_arch() but just in
855 * case lets ensure this is valid.
857 if (num_possible_cpus() == 1)
860 cpu_extra
= (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN
;
862 /* by default this will only continue through for large > 64 CPUs */
863 if (cpu_extra
<= __LOG_BUF_LEN
/ 2)
866 pr_info("log_buf_len individual max cpu contribution: %d bytes\n",
867 __LOG_CPU_MAX_BUF_LEN
);
868 pr_info("log_buf_len total cpu_extra contributions: %d bytes\n",
870 pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN
);
872 log_buf_len_update(cpu_extra
+ __LOG_BUF_LEN
);
875 void __init
setup_log_buf(int early
)
881 if (log_buf
!= __log_buf
)
884 if (!early
&& !new_log_buf_len
)
887 if (!new_log_buf_len
)
892 memblock_virt_alloc(new_log_buf_len
, LOG_ALIGN
);
894 new_log_buf
= memblock_virt_alloc_nopanic(new_log_buf_len
,
898 if (unlikely(!new_log_buf
)) {
899 pr_err("log_buf_len: %ld bytes not available\n",
904 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
905 log_buf_len
= new_log_buf_len
;
906 log_buf
= new_log_buf
;
908 free
= __LOG_BUF_LEN
- log_next_idx
;
909 memcpy(log_buf
, __log_buf
, __LOG_BUF_LEN
);
910 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
912 pr_info("log_buf_len: %d bytes\n", log_buf_len
);
913 pr_info("early log buf free: %d(%d%%)\n",
914 free
, (free
* 100) / __LOG_BUF_LEN
);
917 static bool __read_mostly ignore_loglevel
;
919 static int __init
ignore_loglevel_setup(char *str
)
922 pr_info("debug: ignoring loglevel setting.\n");
927 early_param("ignore_loglevel", ignore_loglevel_setup
);
928 module_param(ignore_loglevel
, bool, S_IRUGO
| S_IWUSR
);
929 MODULE_PARM_DESC(ignore_loglevel
, "ignore loglevel setting, to"
930 "print all kernel messages to the console.");
932 #ifdef CONFIG_BOOT_PRINTK_DELAY
934 static int boot_delay
; /* msecs delay after each printk during bootup */
935 static unsigned long long loops_per_msec
; /* based on boot_delay */
937 static int __init
boot_delay_setup(char *str
)
941 lpj
= preset_lpj
? preset_lpj
: 1000000; /* some guess */
942 loops_per_msec
= (unsigned long long)lpj
/ 1000 * HZ
;
944 get_option(&str
, &boot_delay
);
945 if (boot_delay
> 10 * 1000)
948 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
949 "HZ: %d, loops_per_msec: %llu\n",
950 boot_delay
, preset_lpj
, lpj
, HZ
, loops_per_msec
);
953 early_param("boot_delay", boot_delay_setup
);
955 static void boot_delay_msec(int level
)
957 unsigned long long k
;
958 unsigned long timeout
;
960 if ((boot_delay
== 0 || system_state
!= SYSTEM_BOOTING
)
961 || (level
>= console_loglevel
&& !ignore_loglevel
)) {
965 k
= (unsigned long long)loops_per_msec
* boot_delay
;
967 timeout
= jiffies
+ msecs_to_jiffies(boot_delay
);
972 * use (volatile) jiffies to prevent
973 * compiler reduction; loop termination via jiffies
974 * is secondary and may or may not happen.
976 if (time_after(jiffies
, timeout
))
978 touch_nmi_watchdog();
982 static inline void boot_delay_msec(int level
)
987 static bool printk_time
= IS_ENABLED(CONFIG_PRINTK_TIME
);
988 module_param_named(time
, printk_time
, bool, S_IRUGO
| S_IWUSR
);
990 static size_t print_time(u64 ts
, char *buf
)
992 unsigned long rem_nsec
;
997 rem_nsec
= do_div(ts
, 1000000000);
1000 return snprintf(NULL
, 0, "[%5lu.000000] ", (unsigned long)ts
);
1002 return sprintf(buf
, "[%5lu.%06lu] ",
1003 (unsigned long)ts
, rem_nsec
/ 1000);
1006 static size_t print_prefix(const struct printk_log
*msg
, bool syslog
, char *buf
)
1009 unsigned int prefix
= (msg
->facility
<< 3) | msg
->level
;
1013 len
+= sprintf(buf
, "<%u>", prefix
);
1018 else if (prefix
> 99)
1020 else if (prefix
> 9)
1025 len
+= print_time(msg
->ts_nsec
, buf
? buf
+ len
: NULL
);
1029 static size_t msg_print_text(const struct printk_log
*msg
, enum log_flags prev
,
1030 bool syslog
, char *buf
, size_t size
)
1032 const char *text
= log_text(msg
);
1033 size_t text_size
= msg
->text_len
;
1035 bool newline
= true;
1038 if ((prev
& LOG_CONT
) && !(msg
->flags
& LOG_PREFIX
))
1041 if (msg
->flags
& LOG_CONT
) {
1042 if ((prev
& LOG_CONT
) && !(prev
& LOG_NEWLINE
))
1045 if (!(msg
->flags
& LOG_NEWLINE
))
1050 const char *next
= memchr(text
, '\n', text_size
);
1054 text_len
= next
- text
;
1056 text_size
-= next
- text
;
1058 text_len
= text_size
;
1062 if (print_prefix(msg
, syslog
, NULL
) +
1063 text_len
+ 1 >= size
- len
)
1067 len
+= print_prefix(msg
, syslog
, buf
+ len
);
1068 memcpy(buf
+ len
, text
, text_len
);
1070 if (next
|| newline
)
1073 /* SYSLOG_ACTION_* buffer size only calculation */
1075 len
+= print_prefix(msg
, syslog
, NULL
);
1077 if (next
|| newline
)
1088 static int syslog_print(char __user
*buf
, int size
)
1091 struct printk_log
*msg
;
1094 text
= kmalloc(LOG_LINE_MAX
+ PREFIX_MAX
, GFP_KERNEL
);
1102 raw_spin_lock_irq(&logbuf_lock
);
1103 if (syslog_seq
< log_first_seq
) {
1104 /* messages are gone, move to first one */
1105 syslog_seq
= log_first_seq
;
1106 syslog_idx
= log_first_idx
;
1110 if (syslog_seq
== log_next_seq
) {
1111 raw_spin_unlock_irq(&logbuf_lock
);
1115 skip
= syslog_partial
;
1116 msg
= log_from_idx(syslog_idx
);
1117 n
= msg_print_text(msg
, syslog_prev
, true, text
,
1118 LOG_LINE_MAX
+ PREFIX_MAX
);
1119 if (n
- syslog_partial
<= size
) {
1120 /* message fits into buffer, move forward */
1121 syslog_idx
= log_next(syslog_idx
);
1123 syslog_prev
= msg
->flags
;
1124 n
-= syslog_partial
;
1127 /* partial read(), remember position */
1129 syslog_partial
+= n
;
1132 raw_spin_unlock_irq(&logbuf_lock
);
1137 if (copy_to_user(buf
, text
+ skip
, n
)) {
1152 static int syslog_print_all(char __user
*buf
, int size
, bool clear
)
1157 text
= kmalloc(LOG_LINE_MAX
+ PREFIX_MAX
, GFP_KERNEL
);
1161 raw_spin_lock_irq(&logbuf_lock
);
1166 enum log_flags prev
;
1168 if (clear_seq
< log_first_seq
) {
1169 /* messages are gone, move to first available one */
1170 clear_seq
= log_first_seq
;
1171 clear_idx
= log_first_idx
;
1175 * Find first record that fits, including all following records,
1176 * into the user-provided buffer for this dump.
1181 while (seq
< log_next_seq
) {
1182 struct printk_log
*msg
= log_from_idx(idx
);
1184 len
+= msg_print_text(msg
, prev
, true, NULL
, 0);
1186 idx
= log_next(idx
);
1190 /* move first record forward until length fits into the buffer */
1194 while (len
> size
&& seq
< log_next_seq
) {
1195 struct printk_log
*msg
= log_from_idx(idx
);
1197 len
-= msg_print_text(msg
, prev
, true, NULL
, 0);
1199 idx
= log_next(idx
);
1203 /* last message fitting into this dump */
1204 next_seq
= log_next_seq
;
1207 while (len
>= 0 && seq
< next_seq
) {
1208 struct printk_log
*msg
= log_from_idx(idx
);
1211 textlen
= msg_print_text(msg
, prev
, true, text
,
1212 LOG_LINE_MAX
+ PREFIX_MAX
);
1217 idx
= log_next(idx
);
1221 raw_spin_unlock_irq(&logbuf_lock
);
1222 if (copy_to_user(buf
+ len
, text
, textlen
))
1226 raw_spin_lock_irq(&logbuf_lock
);
1228 if (seq
< log_first_seq
) {
1229 /* messages are gone, move to next one */
1230 seq
= log_first_seq
;
1231 idx
= log_first_idx
;
1238 clear_seq
= log_next_seq
;
1239 clear_idx
= log_next_idx
;
1241 raw_spin_unlock_irq(&logbuf_lock
);
1247 int do_syslog(int type
, char __user
*buf
, int len
, bool from_file
)
1250 static int saved_console_loglevel
= -1;
1253 error
= check_syslog_permissions(type
, from_file
);
1257 error
= security_syslog(type
);
1262 case SYSLOG_ACTION_CLOSE
: /* Close log */
1264 case SYSLOG_ACTION_OPEN
: /* Open log */
1266 case SYSLOG_ACTION_READ
: /* Read from log */
1268 if (!buf
|| len
< 0)
1273 if (!access_ok(VERIFY_WRITE
, buf
, len
)) {
1277 error
= wait_event_interruptible(log_wait
,
1278 syslog_seq
!= log_next_seq
);
1281 error
= syslog_print(buf
, len
);
1283 /* Read/clear last kernel messages */
1284 case SYSLOG_ACTION_READ_CLEAR
:
1287 /* Read last kernel messages */
1288 case SYSLOG_ACTION_READ_ALL
:
1290 if (!buf
|| len
< 0)
1295 if (!access_ok(VERIFY_WRITE
, buf
, len
)) {
1299 error
= syslog_print_all(buf
, len
, clear
);
1301 /* Clear ring buffer */
1302 case SYSLOG_ACTION_CLEAR
:
1303 syslog_print_all(NULL
, 0, true);
1305 /* Disable logging to console */
1306 case SYSLOG_ACTION_CONSOLE_OFF
:
1307 if (saved_console_loglevel
== -1)
1308 saved_console_loglevel
= console_loglevel
;
1309 console_loglevel
= minimum_console_loglevel
;
1311 /* Enable logging to console */
1312 case SYSLOG_ACTION_CONSOLE_ON
:
1313 if (saved_console_loglevel
!= -1) {
1314 console_loglevel
= saved_console_loglevel
;
1315 saved_console_loglevel
= -1;
1318 /* Set level of messages printed to console */
1319 case SYSLOG_ACTION_CONSOLE_LEVEL
:
1321 if (len
< 1 || len
> 8)
1323 if (len
< minimum_console_loglevel
)
1324 len
= minimum_console_loglevel
;
1325 console_loglevel
= len
;
1326 /* Implicitly re-enable logging to console */
1327 saved_console_loglevel
= -1;
1330 /* Number of chars in the log buffer */
1331 case SYSLOG_ACTION_SIZE_UNREAD
:
1332 raw_spin_lock_irq(&logbuf_lock
);
1333 if (syslog_seq
< log_first_seq
) {
1334 /* messages are gone, move to first one */
1335 syslog_seq
= log_first_seq
;
1336 syslog_idx
= log_first_idx
;
1342 * Short-cut for poll(/"proc/kmsg") which simply checks
1343 * for pending data, not the size; return the count of
1344 * records, not the length.
1346 error
= log_next_seq
- syslog_seq
;
1348 u64 seq
= syslog_seq
;
1349 u32 idx
= syslog_idx
;
1350 enum log_flags prev
= syslog_prev
;
1353 while (seq
< log_next_seq
) {
1354 struct printk_log
*msg
= log_from_idx(idx
);
1356 error
+= msg_print_text(msg
, prev
, true, NULL
, 0);
1357 idx
= log_next(idx
);
1361 error
-= syslog_partial
;
1363 raw_spin_unlock_irq(&logbuf_lock
);
1365 /* Size of the log buffer */
1366 case SYSLOG_ACTION_SIZE_BUFFER
:
1367 error
= log_buf_len
;
1377 SYSCALL_DEFINE3(syslog
, int, type
, char __user
*, buf
, int, len
)
1379 return do_syslog(type
, buf
, len
, SYSLOG_FROM_READER
);
1383 * Call the console drivers, asking them to write out
1384 * log_buf[start] to log_buf[end - 1].
1385 * The console_lock must be held.
1387 static void call_console_drivers(int level
, const char *text
, size_t len
)
1389 struct console
*con
;
1391 trace_console(text
, len
);
1393 if (level
>= console_loglevel
&& !ignore_loglevel
)
1395 if (!console_drivers
)
1398 for_each_console(con
) {
1399 if (exclusive_console
&& con
!= exclusive_console
)
1401 if (!(con
->flags
& CON_ENABLED
))
1405 if (!cpu_online(smp_processor_id()) &&
1406 !(con
->flags
& CON_ANYTIME
))
1408 con
->write(con
, text
, len
);
1413 * Zap console related locks when oopsing. Only zap at most once
1414 * every 10 seconds, to leave time for slow consoles to print a
1417 static void zap_locks(void)
1419 static unsigned long oops_timestamp
;
1421 if (time_after_eq(jiffies
, oops_timestamp
) &&
1422 !time_after(jiffies
, oops_timestamp
+ 30 * HZ
))
1425 oops_timestamp
= jiffies
;
1428 /* If a crash is occurring, make sure we can't deadlock */
1429 raw_spin_lock_init(&logbuf_lock
);
1430 /* And make sure that we print immediately */
1431 sema_init(&console_sem
, 1);
1435 * Check if we have any console that is capable of printing while cpu is
1436 * booting or shutting down. Requires console_sem.
1438 static int have_callable_console(void)
1440 struct console
*con
;
1442 for_each_console(con
)
1443 if (con
->flags
& CON_ANYTIME
)
1450 * Can we actually use the console at this time on this cpu?
1452 * Console drivers may assume that per-cpu resources have
1453 * been allocated. So unless they're explicitly marked as
1454 * being able to cope (CON_ANYTIME) don't call them until
1455 * this CPU is officially up.
1457 static inline int can_use_console(unsigned int cpu
)
1459 return cpu_online(cpu
) || have_callable_console();
1463 * Try to get console ownership to actually show the kernel
1464 * messages from a 'printk'. Return true (and with the
1465 * console_lock held, and 'console_locked' set) if it
1466 * is successful, false otherwise.
1468 static int console_trylock_for_printk(unsigned int cpu
)
1470 if (!console_trylock())
1473 * If we can't use the console, we need to release the console
1474 * semaphore by hand to avoid flushing the buffer. We need to hold the
1475 * console semaphore in order to do this test safely.
1477 if (!can_use_console(cpu
)) {
1485 int printk_delay_msec __read_mostly
;
1487 static inline void printk_delay(void)
1489 if (unlikely(printk_delay_msec
)) {
1490 int m
= printk_delay_msec
;
1494 touch_nmi_watchdog();
1500 * Continuation lines are buffered, and not committed to the record buffer
1501 * until the line is complete, or a race forces it. The line fragments
1502 * though, are printed immediately to the consoles to ensure everything has
1503 * reached the console in case of a kernel crash.
1505 static struct cont
{
1506 char buf
[LOG_LINE_MAX
];
1507 size_t len
; /* length == 0 means unused buffer */
1508 size_t cons
; /* bytes written to console */
1509 struct task_struct
*owner
; /* task of first print*/
1510 u64 ts_nsec
; /* time of first print */
1511 u8 level
; /* log level of first message */
1512 u8 facility
; /* log facility of first message */
1513 enum log_flags flags
; /* prefix, newline flags */
1514 bool flushed
:1; /* buffer sealed and committed */
1517 static void cont_flush(enum log_flags flags
)
1526 * If a fragment of this line was directly flushed to the
1527 * console; wait for the console to pick up the rest of the
1528 * line. LOG_NOCONS suppresses a duplicated output.
1530 log_store(cont
.facility
, cont
.level
, flags
| LOG_NOCONS
,
1531 cont
.ts_nsec
, NULL
, 0, cont
.buf
, cont
.len
);
1533 cont
.flushed
= true;
1536 * If no fragment of this line ever reached the console,
1537 * just submit it to the store and free the buffer.
1539 log_store(cont
.facility
, cont
.level
, flags
, 0,
1540 NULL
, 0, cont
.buf
, cont
.len
);
1545 static bool cont_add(int facility
, int level
, const char *text
, size_t len
)
1547 if (cont
.len
&& cont
.flushed
)
1550 if (cont
.len
+ len
> sizeof(cont
.buf
)) {
1551 /* the line gets too long, split it up in separate records */
1552 cont_flush(LOG_CONT
);
1557 cont
.facility
= facility
;
1559 cont
.owner
= current
;
1560 cont
.ts_nsec
= local_clock();
1563 cont
.flushed
= false;
1566 memcpy(cont
.buf
+ cont
.len
, text
, len
);
1569 if (cont
.len
> (sizeof(cont
.buf
) * 80) / 100)
1570 cont_flush(LOG_CONT
);
1575 static size_t cont_print_text(char *text
, size_t size
)
1580 if (cont
.cons
== 0 && (console_prev
& LOG_NEWLINE
)) {
1581 textlen
+= print_time(cont
.ts_nsec
, text
);
1585 len
= cont
.len
- cont
.cons
;
1589 memcpy(text
+ textlen
, cont
.buf
+ cont
.cons
, len
);
1591 cont
.cons
= cont
.len
;
1595 if (cont
.flags
& LOG_NEWLINE
)
1596 text
[textlen
++] = '\n';
1597 /* got everything, release buffer */
1603 asmlinkage
int vprintk_emit(int facility
, int level
,
1604 const char *dict
, size_t dictlen
,
1605 const char *fmt
, va_list args
)
1607 static int recursion_bug
;
1608 static char textbuf
[LOG_LINE_MAX
];
1609 char *text
= textbuf
;
1610 size_t text_len
= 0;
1611 enum log_flags lflags
= 0;
1612 unsigned long flags
;
1614 int printed_len
= 0;
1615 bool in_sched
= false;
1616 /* cpu currently holding logbuf_lock in this function */
1617 static volatile unsigned int logbuf_cpu
= UINT_MAX
;
1619 if (level
== SCHED_MESSAGE_LOGLEVEL
) {
1624 boot_delay_msec(level
);
1627 /* This stops the holder of console_sem just where we want him */
1628 local_irq_save(flags
);
1629 this_cpu
= smp_processor_id();
1632 * Ouch, printk recursed into itself!
1634 if (unlikely(logbuf_cpu
== this_cpu
)) {
1636 * If a crash is occurring during printk() on this CPU,
1637 * then try to get the crash message out but make sure
1638 * we can't deadlock. Otherwise just return to avoid the
1639 * recursion and return - but flag the recursion so that
1640 * it can be printed at the next appropriate moment:
1642 if (!oops_in_progress
&& !lockdep_recursing(current
)) {
1644 goto out_restore_irqs
;
1650 raw_spin_lock(&logbuf_lock
);
1651 logbuf_cpu
= this_cpu
;
1653 if (recursion_bug
) {
1654 static const char recursion_msg
[] =
1655 "BUG: recent printk recursion!";
1658 text_len
= strlen(recursion_msg
);
1659 /* emit KERN_CRIT message */
1660 printed_len
+= log_store(0, 2, LOG_PREFIX
|LOG_NEWLINE
, 0,
1661 NULL
, 0, recursion_msg
, text_len
);
1665 * The printf needs to come first; we need the syslog
1666 * prefix which might be passed-in as a parameter.
1669 text_len
= scnprintf(text
, sizeof(textbuf
),
1670 KERN_WARNING
"[sched_delayed] ");
1672 text_len
+= vscnprintf(text
+ text_len
,
1673 sizeof(textbuf
) - text_len
, fmt
, args
);
1675 /* mark and strip a trailing newline */
1676 if (text_len
&& text
[text_len
-1] == '\n') {
1678 lflags
|= LOG_NEWLINE
;
1681 /* strip kernel syslog prefix and extract log level or control flags */
1682 if (facility
== 0) {
1683 int kern_level
= printk_get_level(text
);
1686 const char *end_of_header
= printk_skip_level(text
);
1687 switch (kern_level
) {
1690 level
= kern_level
- '0';
1691 case 'd': /* KERN_DEFAULT */
1692 lflags
|= LOG_PREFIX
;
1695 * No need to check length here because vscnprintf
1696 * put '\0' at the end of the string. Only valid and
1697 * newly printed level is detected.
1699 text_len
-= end_of_header
- text
;
1700 text
= (char *)end_of_header
;
1705 level
= default_message_loglevel
;
1708 lflags
|= LOG_PREFIX
|LOG_NEWLINE
;
1710 if (!(lflags
& LOG_NEWLINE
)) {
1712 * Flush the conflicting buffer. An earlier newline was missing,
1713 * or another task also prints continuation lines.
1715 if (cont
.len
&& (lflags
& LOG_PREFIX
|| cont
.owner
!= current
))
1716 cont_flush(LOG_NEWLINE
);
1718 /* buffer line if possible, otherwise store it right away */
1719 if (cont_add(facility
, level
, text
, text_len
))
1720 printed_len
+= text_len
;
1722 printed_len
+= log_store(facility
, level
,
1723 lflags
| LOG_CONT
, 0,
1724 dict
, dictlen
, text
, text_len
);
1726 bool stored
= false;
1729 * If an earlier newline was missing and it was the same task,
1730 * either merge it with the current buffer and flush, or if
1731 * there was a race with interrupts (prefix == true) then just
1732 * flush it out and store this line separately.
1733 * If the preceding printk was from a different task and missed
1734 * a newline, flush and append the newline.
1737 if (cont
.owner
== current
&& !(lflags
& LOG_PREFIX
))
1738 stored
= cont_add(facility
, level
, text
,
1740 cont_flush(LOG_NEWLINE
);
1744 printed_len
+= text_len
;
1746 printed_len
+= log_store(facility
, level
, lflags
, 0,
1747 dict
, dictlen
, text
, text_len
);
1750 logbuf_cpu
= UINT_MAX
;
1751 raw_spin_unlock(&logbuf_lock
);
1753 /* If called from the scheduler, we can not call up(). */
1756 * Try to acquire and then immediately release the console
1757 * semaphore. The release will print out buffers and wake up
1758 * /dev/kmsg and syslog() users.
1760 if (console_trylock_for_printk(this_cpu
))
1766 local_irq_restore(flags
);
1769 EXPORT_SYMBOL(vprintk_emit
);
1771 asmlinkage
int vprintk(const char *fmt
, va_list args
)
1773 return vprintk_emit(0, -1, NULL
, 0, fmt
, args
);
1775 EXPORT_SYMBOL(vprintk
);
1777 asmlinkage
int printk_emit(int facility
, int level
,
1778 const char *dict
, size_t dictlen
,
1779 const char *fmt
, ...)
1784 va_start(args
, fmt
);
1785 r
= vprintk_emit(facility
, level
, dict
, dictlen
, fmt
, args
);
1790 EXPORT_SYMBOL(printk_emit
);
1793 * printk - print a kernel message
1794 * @fmt: format string
1796 * This is printk(). It can be called from any context. We want it to work.
1798 * We try to grab the console_lock. If we succeed, it's easy - we log the
1799 * output and call the console drivers. If we fail to get the semaphore, we
1800 * place the output into the log buffer and return. The current holder of
1801 * the console_sem will notice the new output in console_unlock(); and will
1802 * send it to the consoles before releasing the lock.
1804 * One effect of this deferred printing is that code which calls printk() and
1805 * then changes console_loglevel may break. This is because console_loglevel
1806 * is inspected when the actual printing occurs.
1811 * See the vsnprintf() documentation for format string extensions over C99.
1813 asmlinkage __visible
int printk(const char *fmt
, ...)
1818 #ifdef CONFIG_KGDB_KDB
1819 if (unlikely(kdb_trap_printk
)) {
1820 va_start(args
, fmt
);
1821 r
= vkdb_printf(fmt
, args
);
1826 va_start(args
, fmt
);
1827 r
= vprintk_emit(0, -1, NULL
, 0, fmt
, args
);
1832 EXPORT_SYMBOL(printk
);
1834 #else /* CONFIG_PRINTK */
1836 #define LOG_LINE_MAX 0
1837 #define PREFIX_MAX 0
1838 #define LOG_LINE_MAX 0
1839 static u64 syslog_seq
;
1840 static u32 syslog_idx
;
1841 static u64 console_seq
;
1842 static u32 console_idx
;
1843 static enum log_flags syslog_prev
;
1844 static u64 log_first_seq
;
1845 static u32 log_first_idx
;
1846 static u64 log_next_seq
;
1847 static enum log_flags console_prev
;
1848 static struct cont
{
1854 static struct printk_log
*log_from_idx(u32 idx
) { return NULL
; }
1855 static u32
log_next(u32 idx
) { return 0; }
1856 static void call_console_drivers(int level
, const char *text
, size_t len
) {}
1857 static size_t msg_print_text(const struct printk_log
*msg
, enum log_flags prev
,
1858 bool syslog
, char *buf
, size_t size
) { return 0; }
1859 static size_t cont_print_text(char *text
, size_t size
) { return 0; }
1861 #endif /* CONFIG_PRINTK */
1863 #ifdef CONFIG_EARLY_PRINTK
1864 struct console
*early_console
;
1866 void early_vprintk(const char *fmt
, va_list ap
)
1868 if (early_console
) {
1870 int n
= vscnprintf(buf
, sizeof(buf
), fmt
, ap
);
1872 early_console
->write(early_console
, buf
, n
);
1876 asmlinkage __visible
void early_printk(const char *fmt
, ...)
1881 early_vprintk(fmt
, ap
);
1886 static int __add_preferred_console(char *name
, int idx
, char *options
,
1889 struct console_cmdline
*c
;
1893 * See if this tty is not yet registered, and
1894 * if we have a slot free.
1896 for (i
= 0, c
= console_cmdline
;
1897 i
< MAX_CMDLINECONSOLES
&& c
->name
[0];
1899 if (strcmp(c
->name
, name
) == 0 && c
->index
== idx
) {
1901 selected_console
= i
;
1905 if (i
== MAX_CMDLINECONSOLES
)
1908 selected_console
= i
;
1909 strlcpy(c
->name
, name
, sizeof(c
->name
));
1910 c
->options
= options
;
1911 braille_set_options(c
, brl_options
);
1917 * Set up a console. Called via do_early_param() in init/main.c
1918 * for each "console=" parameter in the boot command line.
1920 static int __init
console_setup(char *str
)
1922 char buf
[sizeof(console_cmdline
[0].name
) + 4]; /* 4 for "ttyS" */
1923 char *s
, *options
, *brl_options
= NULL
;
1926 if (_braille_console_setup(&str
, &brl_options
))
1930 * Decode str into name, index, options.
1932 if (str
[0] >= '0' && str
[0] <= '9') {
1933 strcpy(buf
, "ttyS");
1934 strncpy(buf
+ 4, str
, sizeof(buf
) - 5);
1936 strncpy(buf
, str
, sizeof(buf
) - 1);
1938 buf
[sizeof(buf
) - 1] = 0;
1939 if ((options
= strchr(str
, ',')) != NULL
)
1942 if (!strcmp(str
, "ttya"))
1943 strcpy(buf
, "ttyS0");
1944 if (!strcmp(str
, "ttyb"))
1945 strcpy(buf
, "ttyS1");
1947 for (s
= buf
; *s
; s
++)
1948 if ((*s
>= '0' && *s
<= '9') || *s
== ',')
1950 idx
= simple_strtoul(s
, NULL
, 10);
1953 __add_preferred_console(buf
, idx
, options
, brl_options
);
1954 console_set_on_cmdline
= 1;
1957 __setup("console=", console_setup
);
1960 * add_preferred_console - add a device to the list of preferred consoles.
1961 * @name: device name
1962 * @idx: device index
1963 * @options: options for this console
1965 * The last preferred console added will be used for kernel messages
1966 * and stdin/out/err for init. Normally this is used by console_setup
1967 * above to handle user-supplied console arguments; however it can also
1968 * be used by arch-specific code either to override the user or more
1969 * commonly to provide a default console (ie from PROM variables) when
1970 * the user has not supplied one.
1972 int add_preferred_console(char *name
, int idx
, char *options
)
1974 return __add_preferred_console(name
, idx
, options
, NULL
);
1977 int update_console_cmdline(char *name
, int idx
, char *name_new
, int idx_new
, char *options
)
1979 struct console_cmdline
*c
;
1982 for (i
= 0, c
= console_cmdline
;
1983 i
< MAX_CMDLINECONSOLES
&& c
->name
[0];
1985 if (strcmp(c
->name
, name
) == 0 && c
->index
== idx
) {
1986 strlcpy(c
->name
, name_new
, sizeof(c
->name
));
1987 c
->name
[sizeof(c
->name
) - 1] = 0;
1988 c
->options
= options
;
1996 bool console_suspend_enabled
= 1;
1997 EXPORT_SYMBOL(console_suspend_enabled
);
1999 static int __init
console_suspend_disable(char *str
)
2001 console_suspend_enabled
= 0;
2004 __setup("no_console_suspend", console_suspend_disable
);
2005 module_param_named(console_suspend
, console_suspend_enabled
,
2006 bool, S_IRUGO
| S_IWUSR
);
2007 MODULE_PARM_DESC(console_suspend
, "suspend console during suspend"
2008 " and hibernate operations");
2011 * suspend_console - suspend the console subsystem
2013 * This disables printk() while we go into suspend states
2015 void suspend_console(void)
2017 if (!console_suspend_enabled
)
2019 printk("Suspending console(s) (use no_console_suspend to debug)\n");
2021 console_suspended
= 1;
2025 void resume_console(void)
2027 if (!console_suspend_enabled
)
2030 console_suspended
= 0;
2035 * console_cpu_notify - print deferred console messages after CPU hotplug
2036 * @self: notifier struct
2037 * @action: CPU hotplug event
2040 * If printk() is called from a CPU that is not online yet, the messages
2041 * will be spooled but will not show up on the console. This function is
2042 * called when a new CPU comes online (or fails to come up), and ensures
2043 * that any such output gets printed.
2045 static int console_cpu_notify(struct notifier_block
*self
,
2046 unsigned long action
, void *hcpu
)
2051 case CPU_DOWN_FAILED
:
2052 case CPU_UP_CANCELED
:
2060 * console_lock - lock the console system for exclusive use.
2062 * Acquires a lock which guarantees that the caller has
2063 * exclusive access to the console system and the console_drivers list.
2065 * Can sleep, returns nothing.
2067 void console_lock(void)
2072 if (console_suspended
)
2075 console_may_schedule
= 1;
2077 EXPORT_SYMBOL(console_lock
);
2080 * console_trylock - try to lock the console system for exclusive use.
2082 * Try to acquire a lock which guarantees that the caller has exclusive
2083 * access to the console system and the console_drivers list.
2085 * returns 1 on success, and 0 on failure to acquire the lock.
2087 int console_trylock(void)
2089 if (down_trylock_console_sem())
2091 if (console_suspended
) {
2096 console_may_schedule
= 0;
2099 EXPORT_SYMBOL(console_trylock
);
2101 int is_console_locked(void)
2103 return console_locked
;
2106 static void console_cont_flush(char *text
, size_t size
)
2108 unsigned long flags
;
2111 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2117 * We still queue earlier records, likely because the console was
2118 * busy. The earlier ones need to be printed before this one, we
2119 * did not flush any fragment so far, so just let it queue up.
2121 if (console_seq
< log_next_seq
&& !cont
.cons
)
2124 len
= cont_print_text(text
, size
);
2125 raw_spin_unlock(&logbuf_lock
);
2126 stop_critical_timings();
2127 call_console_drivers(cont
.level
, text
, len
);
2128 start_critical_timings();
2129 local_irq_restore(flags
);
2132 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2136 * console_unlock - unlock the console system
2138 * Releases the console_lock which the caller holds on the console system
2139 * and the console driver list.
2141 * While the console_lock was held, console output may have been buffered
2142 * by printk(). If this is the case, console_unlock(); emits
2143 * the output prior to releasing the lock.
2145 * If there is output waiting, we wake /dev/kmsg and syslog() users.
2147 * console_unlock(); may be called from any context.
2149 void console_unlock(void)
2151 static char text
[LOG_LINE_MAX
+ PREFIX_MAX
];
2152 static u64 seen_seq
;
2153 unsigned long flags
;
2154 bool wake_klogd
= false;
2157 if (console_suspended
) {
2162 console_may_schedule
= 0;
2164 /* flush buffered message fragment immediately to console */
2165 console_cont_flush(text
, sizeof(text
));
2168 struct printk_log
*msg
;
2172 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2173 if (seen_seq
!= log_next_seq
) {
2175 seen_seq
= log_next_seq
;
2178 if (console_seq
< log_first_seq
) {
2179 len
= sprintf(text
, "** %u printk messages dropped ** ",
2180 (unsigned)(log_first_seq
- console_seq
));
2182 /* messages are gone, move to first one */
2183 console_seq
= log_first_seq
;
2184 console_idx
= log_first_idx
;
2190 if (console_seq
== log_next_seq
)
2193 msg
= log_from_idx(console_idx
);
2194 if (msg
->flags
& LOG_NOCONS
) {
2196 * Skip record we have buffered and already printed
2197 * directly to the console when we received it.
2199 console_idx
= log_next(console_idx
);
2202 * We will get here again when we register a new
2203 * CON_PRINTBUFFER console. Clear the flag so we
2204 * will properly dump everything later.
2206 msg
->flags
&= ~LOG_NOCONS
;
2207 console_prev
= msg
->flags
;
2212 len
+= msg_print_text(msg
, console_prev
, false,
2213 text
+ len
, sizeof(text
) - len
);
2214 console_idx
= log_next(console_idx
);
2216 console_prev
= msg
->flags
;
2217 raw_spin_unlock(&logbuf_lock
);
2219 stop_critical_timings(); /* don't trace print latency */
2220 call_console_drivers(level
, text
, len
);
2221 start_critical_timings();
2222 local_irq_restore(flags
);
2226 /* Release the exclusive_console once it is used */
2227 if (unlikely(exclusive_console
))
2228 exclusive_console
= NULL
;
2230 raw_spin_unlock(&logbuf_lock
);
2235 * Someone could have filled up the buffer again, so re-check if there's
2236 * something to flush. In case we cannot trylock the console_sem again,
2237 * there's a new owner and the console_unlock() from them will do the
2238 * flush, no worries.
2240 raw_spin_lock(&logbuf_lock
);
2241 retry
= console_seq
!= log_next_seq
;
2242 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2244 if (retry
&& console_trylock())
2250 EXPORT_SYMBOL(console_unlock
);
2253 * console_conditional_schedule - yield the CPU if required
2255 * If the console code is currently allowed to sleep, and
2256 * if this CPU should yield the CPU to another task, do
2259 * Must be called within console_lock();.
2261 void __sched
console_conditional_schedule(void)
2263 if (console_may_schedule
)
2266 EXPORT_SYMBOL(console_conditional_schedule
);
2268 void console_unblank(void)
2273 * console_unblank can no longer be called in interrupt context unless
2274 * oops_in_progress is set to 1..
2276 if (oops_in_progress
) {
2277 if (down_trylock_console_sem() != 0)
2283 console_may_schedule
= 0;
2285 if ((c
->flags
& CON_ENABLED
) && c
->unblank
)
2291 * Return the console tty driver structure and its associated index
2293 struct tty_driver
*console_device(int *index
)
2296 struct tty_driver
*driver
= NULL
;
2299 for_each_console(c
) {
2302 driver
= c
->device(c
, index
);
2311 * Prevent further output on the passed console device so that (for example)
2312 * serial drivers can disable console output before suspending a port, and can
2313 * re-enable output afterwards.
2315 void console_stop(struct console
*console
)
2318 console
->flags
&= ~CON_ENABLED
;
2321 EXPORT_SYMBOL(console_stop
);
2323 void console_start(struct console
*console
)
2326 console
->flags
|= CON_ENABLED
;
2329 EXPORT_SYMBOL(console_start
);
2331 static int __read_mostly keep_bootcon
;
2333 static int __init
keep_bootcon_setup(char *str
)
2336 pr_info("debug: skip boot console de-registration.\n");
2341 early_param("keep_bootcon", keep_bootcon_setup
);
2344 * The console driver calls this routine during kernel initialization
2345 * to register the console printing procedure with printk() and to
2346 * print any messages that were printed by the kernel before the
2347 * console driver was initialized.
2349 * This can happen pretty early during the boot process (because of
2350 * early_printk) - sometimes before setup_arch() completes - be careful
2351 * of what kernel features are used - they may not be initialised yet.
2353 * There are two types of consoles - bootconsoles (early_printk) and
2354 * "real" consoles (everything which is not a bootconsole) which are
2355 * handled differently.
2356 * - Any number of bootconsoles can be registered at any time.
2357 * - As soon as a "real" console is registered, all bootconsoles
2358 * will be unregistered automatically.
2359 * - Once a "real" console is registered, any attempt to register a
2360 * bootconsoles will be rejected
2362 void register_console(struct console
*newcon
)
2365 unsigned long flags
;
2366 struct console
*bcon
= NULL
;
2367 struct console_cmdline
*c
;
2369 if (console_drivers
)
2370 for_each_console(bcon
)
2371 if (WARN(bcon
== newcon
,
2372 "console '%s%d' already registered\n",
2373 bcon
->name
, bcon
->index
))
2377 * before we register a new CON_BOOT console, make sure we don't
2378 * already have a valid console
2380 if (console_drivers
&& newcon
->flags
& CON_BOOT
) {
2381 /* find the last or real console */
2382 for_each_console(bcon
) {
2383 if (!(bcon
->flags
& CON_BOOT
)) {
2384 pr_info("Too late to register bootconsole %s%d\n",
2385 newcon
->name
, newcon
->index
);
2391 if (console_drivers
&& console_drivers
->flags
& CON_BOOT
)
2392 bcon
= console_drivers
;
2394 if (preferred_console
< 0 || bcon
|| !console_drivers
)
2395 preferred_console
= selected_console
;
2397 if (newcon
->early_setup
)
2398 newcon
->early_setup();
2401 * See if we want to use this console driver. If we
2402 * didn't select a console we take the first one
2403 * that registers here.
2405 if (preferred_console
< 0) {
2406 if (newcon
->index
< 0)
2408 if (newcon
->setup
== NULL
||
2409 newcon
->setup(newcon
, NULL
) == 0) {
2410 newcon
->flags
|= CON_ENABLED
;
2411 if (newcon
->device
) {
2412 newcon
->flags
|= CON_CONSDEV
;
2413 preferred_console
= 0;
2419 * See if this console matches one we selected on
2422 for (i
= 0, c
= console_cmdline
;
2423 i
< MAX_CMDLINECONSOLES
&& c
->name
[0];
2425 if (strcmp(c
->name
, newcon
->name
) != 0)
2427 if (newcon
->index
>= 0 &&
2428 newcon
->index
!= c
->index
)
2430 if (newcon
->index
< 0)
2431 newcon
->index
= c
->index
;
2433 if (_braille_register_console(newcon
, c
))
2436 if (newcon
->setup
&&
2437 newcon
->setup(newcon
, console_cmdline
[i
].options
) != 0)
2439 newcon
->flags
|= CON_ENABLED
;
2440 newcon
->index
= c
->index
;
2441 if (i
== selected_console
) {
2442 newcon
->flags
|= CON_CONSDEV
;
2443 preferred_console
= selected_console
;
2448 if (!(newcon
->flags
& CON_ENABLED
))
2452 * If we have a bootconsole, and are switching to a real console,
2453 * don't print everything out again, since when the boot console, and
2454 * the real console are the same physical device, it's annoying to
2455 * see the beginning boot messages twice
2457 if (bcon
&& ((newcon
->flags
& (CON_CONSDEV
| CON_BOOT
)) == CON_CONSDEV
))
2458 newcon
->flags
&= ~CON_PRINTBUFFER
;
2461 * Put this console in the list - keep the
2462 * preferred driver at the head of the list.
2465 if ((newcon
->flags
& CON_CONSDEV
) || console_drivers
== NULL
) {
2466 newcon
->next
= console_drivers
;
2467 console_drivers
= newcon
;
2469 newcon
->next
->flags
&= ~CON_CONSDEV
;
2471 newcon
->next
= console_drivers
->next
;
2472 console_drivers
->next
= newcon
;
2474 if (newcon
->flags
& CON_PRINTBUFFER
) {
2476 * console_unlock(); will print out the buffered messages
2479 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2480 console_seq
= syslog_seq
;
2481 console_idx
= syslog_idx
;
2482 console_prev
= syslog_prev
;
2483 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2485 * We're about to replay the log buffer. Only do this to the
2486 * just-registered console to avoid excessive message spam to
2487 * the already-registered consoles.
2489 exclusive_console
= newcon
;
2492 console_sysfs_notify();
2495 * By unregistering the bootconsoles after we enable the real console
2496 * we get the "console xxx enabled" message on all the consoles -
2497 * boot consoles, real consoles, etc - this is to ensure that end
2498 * users know there might be something in the kernel's log buffer that
2499 * went to the bootconsole (that they do not see on the real console)
2501 pr_info("%sconsole [%s%d] enabled\n",
2502 (newcon
->flags
& CON_BOOT
) ? "boot" : "" ,
2503 newcon
->name
, newcon
->index
);
2505 ((newcon
->flags
& (CON_CONSDEV
| CON_BOOT
)) == CON_CONSDEV
) &&
2507 /* We need to iterate through all boot consoles, to make
2508 * sure we print everything out, before we unregister them.
2510 for_each_console(bcon
)
2511 if (bcon
->flags
& CON_BOOT
)
2512 unregister_console(bcon
);
2515 EXPORT_SYMBOL(register_console
);
2517 int unregister_console(struct console
*console
)
2519 struct console
*a
, *b
;
2522 pr_info("%sconsole [%s%d] disabled\n",
2523 (console
->flags
& CON_BOOT
) ? "boot" : "" ,
2524 console
->name
, console
->index
);
2526 res
= _braille_unregister_console(console
);
2532 if (console_drivers
== console
) {
2533 console_drivers
=console
->next
;
2535 } else if (console_drivers
) {
2536 for (a
=console_drivers
->next
, b
=console_drivers
;
2537 a
; b
=a
, a
=b
->next
) {
2547 * If this isn't the last console and it has CON_CONSDEV set, we
2548 * need to set it on the next preferred console.
2550 if (console_drivers
!= NULL
&& console
->flags
& CON_CONSDEV
)
2551 console_drivers
->flags
|= CON_CONSDEV
;
2553 console
->flags
&= ~CON_ENABLED
;
2555 console_sysfs_notify();
2558 EXPORT_SYMBOL(unregister_console
);
2560 static int __init
printk_late_init(void)
2562 struct console
*con
;
2564 for_each_console(con
) {
2565 if (!keep_bootcon
&& con
->flags
& CON_BOOT
) {
2566 unregister_console(con
);
2569 hotcpu_notifier(console_cpu_notify
, 0);
2572 late_initcall(printk_late_init
);
2574 #if defined CONFIG_PRINTK
2576 * Delayed printk version, for scheduler-internal messages:
2578 #define PRINTK_PENDING_WAKEUP 0x01
2579 #define PRINTK_PENDING_OUTPUT 0x02
2581 static DEFINE_PER_CPU(int, printk_pending
);
2583 static void wake_up_klogd_work_func(struct irq_work
*irq_work
)
2585 int pending
= __this_cpu_xchg(printk_pending
, 0);
2587 if (pending
& PRINTK_PENDING_OUTPUT
) {
2588 /* If trylock fails, someone else is doing the printing */
2589 if (console_trylock())
2593 if (pending
& PRINTK_PENDING_WAKEUP
)
2594 wake_up_interruptible(&log_wait
);
2597 static DEFINE_PER_CPU(struct irq_work
, wake_up_klogd_work
) = {
2598 .func
= wake_up_klogd_work_func
,
2599 .flags
= IRQ_WORK_LAZY
,
2602 void wake_up_klogd(void)
2605 if (waitqueue_active(&log_wait
)) {
2606 this_cpu_or(printk_pending
, PRINTK_PENDING_WAKEUP
);
2607 irq_work_queue(&__get_cpu_var(wake_up_klogd_work
));
2612 int printk_deferred(const char *fmt
, ...)
2618 va_start(args
, fmt
);
2619 r
= vprintk_emit(0, SCHED_MESSAGE_LOGLEVEL
, NULL
, 0, fmt
, args
);
2622 __this_cpu_or(printk_pending
, PRINTK_PENDING_OUTPUT
);
2623 irq_work_queue(&__get_cpu_var(wake_up_klogd_work
));
2630 * printk rate limiting, lifted from the networking subsystem.
2632 * This enforces a rate limit: not more than 10 kernel messages
2633 * every 5s to make a denial-of-service attack impossible.
2635 DEFINE_RATELIMIT_STATE(printk_ratelimit_state
, 5 * HZ
, 10);
2637 int __printk_ratelimit(const char *func
)
2639 return ___ratelimit(&printk_ratelimit_state
, func
);
2641 EXPORT_SYMBOL(__printk_ratelimit
);
2644 * printk_timed_ratelimit - caller-controlled printk ratelimiting
2645 * @caller_jiffies: pointer to caller's state
2646 * @interval_msecs: minimum interval between prints
2648 * printk_timed_ratelimit() returns true if more than @interval_msecs
2649 * milliseconds have elapsed since the last time printk_timed_ratelimit()
2652 bool printk_timed_ratelimit(unsigned long *caller_jiffies
,
2653 unsigned int interval_msecs
)
2655 if (*caller_jiffies
== 0
2656 || !time_in_range(jiffies
, *caller_jiffies
,
2658 + msecs_to_jiffies(interval_msecs
))) {
2659 *caller_jiffies
= jiffies
;
2664 EXPORT_SYMBOL(printk_timed_ratelimit
);
2666 static DEFINE_SPINLOCK(dump_list_lock
);
2667 static LIST_HEAD(dump_list
);
2670 * kmsg_dump_register - register a kernel log dumper.
2671 * @dumper: pointer to the kmsg_dumper structure
2673 * Adds a kernel log dumper to the system. The dump callback in the
2674 * structure will be called when the kernel oopses or panics and must be
2675 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
2677 int kmsg_dump_register(struct kmsg_dumper
*dumper
)
2679 unsigned long flags
;
2682 /* The dump callback needs to be set */
2686 spin_lock_irqsave(&dump_list_lock
, flags
);
2687 /* Don't allow registering multiple times */
2688 if (!dumper
->registered
) {
2689 dumper
->registered
= 1;
2690 list_add_tail_rcu(&dumper
->list
, &dump_list
);
2693 spin_unlock_irqrestore(&dump_list_lock
, flags
);
2697 EXPORT_SYMBOL_GPL(kmsg_dump_register
);
2700 * kmsg_dump_unregister - unregister a kmsg dumper.
2701 * @dumper: pointer to the kmsg_dumper structure
2703 * Removes a dump device from the system. Returns zero on success and
2704 * %-EINVAL otherwise.
2706 int kmsg_dump_unregister(struct kmsg_dumper
*dumper
)
2708 unsigned long flags
;
2711 spin_lock_irqsave(&dump_list_lock
, flags
);
2712 if (dumper
->registered
) {
2713 dumper
->registered
= 0;
2714 list_del_rcu(&dumper
->list
);
2717 spin_unlock_irqrestore(&dump_list_lock
, flags
);
2722 EXPORT_SYMBOL_GPL(kmsg_dump_unregister
);
2724 static bool always_kmsg_dump
;
2725 module_param_named(always_kmsg_dump
, always_kmsg_dump
, bool, S_IRUGO
| S_IWUSR
);
2728 * kmsg_dump - dump kernel log to kernel message dumpers.
2729 * @reason: the reason (oops, panic etc) for dumping
2731 * Call each of the registered dumper's dump() callback, which can
2732 * retrieve the kmsg records with kmsg_dump_get_line() or
2733 * kmsg_dump_get_buffer().
2735 void kmsg_dump(enum kmsg_dump_reason reason
)
2737 struct kmsg_dumper
*dumper
;
2738 unsigned long flags
;
2740 if ((reason
> KMSG_DUMP_OOPS
) && !always_kmsg_dump
)
2744 list_for_each_entry_rcu(dumper
, &dump_list
, list
) {
2745 if (dumper
->max_reason
&& reason
> dumper
->max_reason
)
2748 /* initialize iterator with data about the stored records */
2749 dumper
->active
= true;
2751 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2752 dumper
->cur_seq
= clear_seq
;
2753 dumper
->cur_idx
= clear_idx
;
2754 dumper
->next_seq
= log_next_seq
;
2755 dumper
->next_idx
= log_next_idx
;
2756 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2758 /* invoke dumper which will iterate over records */
2759 dumper
->dump(dumper
, reason
);
2761 /* reset iterator */
2762 dumper
->active
= false;
2768 * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
2769 * @dumper: registered kmsg dumper
2770 * @syslog: include the "<4>" prefixes
2771 * @line: buffer to copy the line to
2772 * @size: maximum size of the buffer
2773 * @len: length of line placed into buffer
2775 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2776 * record, and copy one record into the provided buffer.
2778 * Consecutive calls will return the next available record moving
2779 * towards the end of the buffer with the youngest messages.
2781 * A return value of FALSE indicates that there are no more records to
2784 * The function is similar to kmsg_dump_get_line(), but grabs no locks.
2786 bool kmsg_dump_get_line_nolock(struct kmsg_dumper
*dumper
, bool syslog
,
2787 char *line
, size_t size
, size_t *len
)
2789 struct printk_log
*msg
;
2793 if (!dumper
->active
)
2796 if (dumper
->cur_seq
< log_first_seq
) {
2797 /* messages are gone, move to first available one */
2798 dumper
->cur_seq
= log_first_seq
;
2799 dumper
->cur_idx
= log_first_idx
;
2803 if (dumper
->cur_seq
>= log_next_seq
)
2806 msg
= log_from_idx(dumper
->cur_idx
);
2807 l
= msg_print_text(msg
, 0, syslog
, line
, size
);
2809 dumper
->cur_idx
= log_next(dumper
->cur_idx
);
2819 * kmsg_dump_get_line - retrieve one kmsg log line
2820 * @dumper: registered kmsg dumper
2821 * @syslog: include the "<4>" prefixes
2822 * @line: buffer to copy the line to
2823 * @size: maximum size of the buffer
2824 * @len: length of line placed into buffer
2826 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2827 * record, and copy one record into the provided buffer.
2829 * Consecutive calls will return the next available record moving
2830 * towards the end of the buffer with the youngest messages.
2832 * A return value of FALSE indicates that there are no more records to
2835 bool kmsg_dump_get_line(struct kmsg_dumper
*dumper
, bool syslog
,
2836 char *line
, size_t size
, size_t *len
)
2838 unsigned long flags
;
2841 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2842 ret
= kmsg_dump_get_line_nolock(dumper
, syslog
, line
, size
, len
);
2843 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2847 EXPORT_SYMBOL_GPL(kmsg_dump_get_line
);
2850 * kmsg_dump_get_buffer - copy kmsg log lines
2851 * @dumper: registered kmsg dumper
2852 * @syslog: include the "<4>" prefixes
2853 * @buf: buffer to copy the line to
2854 * @size: maximum size of the buffer
2855 * @len: length of line placed into buffer
2857 * Start at the end of the kmsg buffer and fill the provided buffer
2858 * with as many of the the *youngest* kmsg records that fit into it.
2859 * If the buffer is large enough, all available kmsg records will be
2860 * copied with a single call.
2862 * Consecutive calls will fill the buffer with the next block of
2863 * available older records, not including the earlier retrieved ones.
2865 * A return value of FALSE indicates that there are no more records to
2868 bool kmsg_dump_get_buffer(struct kmsg_dumper
*dumper
, bool syslog
,
2869 char *buf
, size_t size
, size_t *len
)
2871 unsigned long flags
;
2876 enum log_flags prev
;
2880 if (!dumper
->active
)
2883 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2884 if (dumper
->cur_seq
< log_first_seq
) {
2885 /* messages are gone, move to first available one */
2886 dumper
->cur_seq
= log_first_seq
;
2887 dumper
->cur_idx
= log_first_idx
;
2891 if (dumper
->cur_seq
>= dumper
->next_seq
) {
2892 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2896 /* calculate length of entire buffer */
2897 seq
= dumper
->cur_seq
;
2898 idx
= dumper
->cur_idx
;
2900 while (seq
< dumper
->next_seq
) {
2901 struct printk_log
*msg
= log_from_idx(idx
);
2903 l
+= msg_print_text(msg
, prev
, true, NULL
, 0);
2904 idx
= log_next(idx
);
2909 /* move first record forward until length fits into the buffer */
2910 seq
= dumper
->cur_seq
;
2911 idx
= dumper
->cur_idx
;
2913 while (l
> size
&& seq
< dumper
->next_seq
) {
2914 struct printk_log
*msg
= log_from_idx(idx
);
2916 l
-= msg_print_text(msg
, prev
, true, NULL
, 0);
2917 idx
= log_next(idx
);
2922 /* last message in next interation */
2927 while (seq
< dumper
->next_seq
) {
2928 struct printk_log
*msg
= log_from_idx(idx
);
2930 l
+= msg_print_text(msg
, prev
, syslog
, buf
+ l
, size
- l
);
2931 idx
= log_next(idx
);
2936 dumper
->next_seq
= next_seq
;
2937 dumper
->next_idx
= next_idx
;
2939 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2945 EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer
);
2948 * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
2949 * @dumper: registered kmsg dumper
2951 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2952 * kmsg_dump_get_buffer() can be called again and used multiple
2953 * times within the same dumper.dump() callback.
2955 * The function is similar to kmsg_dump_rewind(), but grabs no locks.
2957 void kmsg_dump_rewind_nolock(struct kmsg_dumper
*dumper
)
2959 dumper
->cur_seq
= clear_seq
;
2960 dumper
->cur_idx
= clear_idx
;
2961 dumper
->next_seq
= log_next_seq
;
2962 dumper
->next_idx
= log_next_idx
;
2966 * kmsg_dump_rewind - reset the interator
2967 * @dumper: registered kmsg dumper
2969 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2970 * kmsg_dump_get_buffer() can be called again and used multiple
2971 * times within the same dumper.dump() callback.
2973 void kmsg_dump_rewind(struct kmsg_dumper
*dumper
)
2975 unsigned long flags
;
2977 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2978 kmsg_dump_rewind_nolock(dumper
);
2979 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2981 EXPORT_SYMBOL_GPL(kmsg_dump_rewind
);
2983 static char dump_stack_arch_desc_str
[128];
2986 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
2987 * @fmt: printf-style format string
2988 * @...: arguments for the format string
2990 * The configured string will be printed right after utsname during task
2991 * dumps. Usually used to add arch-specific system identifiers. If an
2992 * arch wants to make use of such an ID string, it should initialize this
2993 * as soon as possible during boot.
2995 void __init
dump_stack_set_arch_desc(const char *fmt
, ...)
2999 va_start(args
, fmt
);
3000 vsnprintf(dump_stack_arch_desc_str
, sizeof(dump_stack_arch_desc_str
),
3006 * dump_stack_print_info - print generic debug info for dump_stack()
3007 * @log_lvl: log level
3009 * Arch-specific dump_stack() implementations can use this function to
3010 * print out the same debug information as the generic dump_stack().
3012 void dump_stack_print_info(const char *log_lvl
)
3014 printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
3015 log_lvl
, raw_smp_processor_id(), current
->pid
, current
->comm
,
3016 print_tainted(), init_utsname()->release
,
3017 (int)strcspn(init_utsname()->version
, " "),
3018 init_utsname()->version
);
3020 if (dump_stack_arch_desc_str
[0] != '\0')
3021 printk("%sHardware name: %s\n",
3022 log_lvl
, dump_stack_arch_desc_str
);
3024 print_worker_info(log_lvl
, current
);
3028 * show_regs_print_info - print generic debug info for show_regs()
3029 * @log_lvl: log level
3031 * show_regs() implementations can use this function to print out generic
3032 * debug information.
3034 void show_regs_print_info(const char *log_lvl
)
3036 dump_stack_print_info(log_lvl
);
3038 printk("%stask: %p ti: %p task.ti: %p\n",
3039 log_lvl
, current
, current_thread_info(),
3040 task_thread_info(current
));