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 DEFAULT_MESSAGE_LOGLEVEL
, /* 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 are racing, but it helps tracking those weird code
117 * path 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 both entries are maintained when messages
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 static char __log_buf
[__LOG_BUF_LEN
] __aligned(LOG_ALIGN
);
270 static char *log_buf
= __log_buf
;
271 static u32 log_buf_len
= __LOG_BUF_LEN
;
273 /* human readable text of the record */
274 static char *log_text(const struct printk_log
*msg
)
276 return (char *)msg
+ sizeof(struct printk_log
);
279 /* optional key/value pair dictionary attached to the record */
280 static char *log_dict(const struct printk_log
*msg
)
282 return (char *)msg
+ sizeof(struct printk_log
) + msg
->text_len
;
285 /* get record by index; idx must point to valid msg */
286 static struct printk_log
*log_from_idx(u32 idx
)
288 struct printk_log
*msg
= (struct printk_log
*)(log_buf
+ idx
);
291 * A length == 0 record is the end of buffer marker. Wrap around and
292 * read the message at the start of the buffer.
295 return (struct printk_log
*)log_buf
;
299 /* get next record; idx must point to valid msg */
300 static u32
log_next(u32 idx
)
302 struct printk_log
*msg
= (struct printk_log
*)(log_buf
+ idx
);
304 /* length == 0 indicates the end of the buffer; wrap */
306 * A length == 0 record is the end of buffer marker. Wrap around and
307 * read the message at the start of the buffer as *this* one, and
308 * return the one after that.
311 msg
= (struct printk_log
*)log_buf
;
314 return idx
+ msg
->len
;
318 * Check whether there is enough free space for the given message.
320 * The same values of first_idx and next_idx mean that the buffer
321 * is either empty or full.
323 * If the buffer is empty, we must respect the position of the indexes.
324 * They cannot be reset to the beginning of the buffer.
326 static int logbuf_has_space(u32 msg_size
, bool empty
)
330 if (log_next_idx
> log_first_idx
|| empty
)
331 free
= max(log_buf_len
- log_next_idx
, log_first_idx
);
333 free
= log_first_idx
- log_next_idx
;
336 * We need space also for an empty header that signalizes wrapping
339 return free
>= msg_size
+ sizeof(struct printk_log
);
342 static int log_make_free_space(u32 msg_size
)
344 while (log_first_seq
< log_next_seq
) {
345 if (logbuf_has_space(msg_size
, false))
347 /* drop old messages until we have enough continuous space */
348 log_first_idx
= log_next(log_first_idx
);
352 /* sequence numbers are equal, so the log buffer is empty */
353 if (logbuf_has_space(msg_size
, true))
359 /* compute the message size including the padding bytes */
360 static u32
msg_used_size(u16 text_len
, u16 dict_len
, u32
*pad_len
)
364 size
= sizeof(struct printk_log
) + text_len
+ dict_len
;
365 *pad_len
= (-size
) & (LOG_ALIGN
- 1);
372 * Define how much of the log buffer we could take at maximum. The value
373 * must be greater than two. Note that only half of the buffer is available
374 * when the index points to the middle.
376 #define MAX_LOG_TAKE_PART 4
377 static const char trunc_msg
[] = "<truncated>";
379 static u32
truncate_msg(u16
*text_len
, u16
*trunc_msg_len
,
380 u16
*dict_len
, u32
*pad_len
)
383 * The message should not take the whole buffer. Otherwise, it might
384 * get removed too soon.
386 u32 max_text_len
= log_buf_len
/ MAX_LOG_TAKE_PART
;
387 if (*text_len
> max_text_len
)
388 *text_len
= max_text_len
;
389 /* enable the warning message */
390 *trunc_msg_len
= strlen(trunc_msg
);
391 /* disable the "dict" completely */
393 /* compute the size again, count also the warning message */
394 return msg_used_size(*text_len
+ *trunc_msg_len
, 0, pad_len
);
397 /* insert record into the buffer, discard old ones, update heads */
398 static int log_store(int facility
, int level
,
399 enum log_flags flags
, u64 ts_nsec
,
400 const char *dict
, u16 dict_len
,
401 const char *text
, u16 text_len
)
403 struct printk_log
*msg
;
405 u16 trunc_msg_len
= 0;
407 /* number of '\0' padding bytes to next message */
408 size
= msg_used_size(text_len
, dict_len
, &pad_len
);
410 if (log_make_free_space(size
)) {
411 /* truncate the message if it is too long for empty buffer */
412 size
= truncate_msg(&text_len
, &trunc_msg_len
,
413 &dict_len
, &pad_len
);
414 /* survive when the log buffer is too small for trunc_msg */
415 if (log_make_free_space(size
))
419 if (log_next_idx
+ size
+ sizeof(struct printk_log
) > log_buf_len
) {
421 * This message + an additional empty header does not fit
422 * at the end of the buffer. Add an empty header with len == 0
423 * to signify a wrap around.
425 memset(log_buf
+ log_next_idx
, 0, sizeof(struct printk_log
));
430 msg
= (struct printk_log
*)(log_buf
+ log_next_idx
);
431 memcpy(log_text(msg
), text
, text_len
);
432 msg
->text_len
= text_len
;
434 memcpy(log_text(msg
) + text_len
, trunc_msg
, trunc_msg_len
);
435 msg
->text_len
+= trunc_msg_len
;
437 memcpy(log_dict(msg
), dict
, dict_len
);
438 msg
->dict_len
= dict_len
;
439 msg
->facility
= facility
;
440 msg
->level
= level
& 7;
441 msg
->flags
= flags
& 0x1f;
443 msg
->ts_nsec
= ts_nsec
;
445 msg
->ts_nsec
= local_clock();
446 memset(log_dict(msg
) + dict_len
, 0, pad_len
);
450 log_next_idx
+= msg
->len
;
453 return msg
->text_len
;
456 #ifdef CONFIG_SECURITY_DMESG_RESTRICT
457 int dmesg_restrict
= 1;
462 static int syslog_action_restricted(int type
)
467 * Unless restricted, we allow "read all" and "get buffer size"
470 return type
!= SYSLOG_ACTION_READ_ALL
&&
471 type
!= SYSLOG_ACTION_SIZE_BUFFER
;
474 static int check_syslog_permissions(int type
, bool from_file
)
477 * If this is from /proc/kmsg and we've already opened it, then we've
478 * already done the capabilities checks at open time.
480 if (from_file
&& type
!= SYSLOG_ACTION_OPEN
)
483 if (syslog_action_restricted(type
)) {
484 if (capable(CAP_SYSLOG
))
487 * For historical reasons, accept CAP_SYS_ADMIN too, with
490 if (capable(CAP_SYS_ADMIN
)) {
491 pr_warn_once("%s (%d): Attempt to access syslog with "
492 "CAP_SYS_ADMIN but no CAP_SYSLOG "
494 current
->comm
, task_pid_nr(current
));
499 return security_syslog(type
);
503 /* /dev/kmsg - userspace message inject/listen interface */
504 struct devkmsg_user
{
512 static ssize_t
devkmsg_writev(struct kiocb
*iocb
, const struct iovec
*iv
,
513 unsigned long count
, loff_t pos
)
517 int level
= default_message_loglevel
;
518 int facility
= 1; /* LOG_USER */
519 size_t len
= iov_length(iv
, count
);
522 if (len
> LOG_LINE_MAX
)
524 buf
= kmalloc(len
+1, GFP_KERNEL
);
529 for (i
= 0; i
< count
; i
++) {
530 if (copy_from_user(line
, iv
[i
].iov_base
, iv
[i
].iov_len
)) {
534 line
+= iv
[i
].iov_len
;
538 * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
539 * the decimal value represents 32bit, the lower 3 bit are the log
540 * level, the rest are the log facility.
542 * If no prefix or no userspace facility is specified, we
543 * enforce LOG_USER, to be able to reliably distinguish
544 * kernel-generated messages from userspace-injected ones.
547 if (line
[0] == '<') {
550 i
= simple_strtoul(line
+1, &endp
, 10);
551 if (endp
&& endp
[0] == '>') {
562 printk_emit(facility
, level
, NULL
, 0, "%s", line
);
568 static ssize_t
devkmsg_read(struct file
*file
, char __user
*buf
,
569 size_t count
, loff_t
*ppos
)
571 struct devkmsg_user
*user
= file
->private_data
;
572 struct printk_log
*msg
;
582 ret
= mutex_lock_interruptible(&user
->lock
);
585 raw_spin_lock_irq(&logbuf_lock
);
586 while (user
->seq
== log_next_seq
) {
587 if (file
->f_flags
& O_NONBLOCK
) {
589 raw_spin_unlock_irq(&logbuf_lock
);
593 raw_spin_unlock_irq(&logbuf_lock
);
594 ret
= wait_event_interruptible(log_wait
,
595 user
->seq
!= log_next_seq
);
598 raw_spin_lock_irq(&logbuf_lock
);
601 if (user
->seq
< log_first_seq
) {
602 /* our last seen message is gone, return error and reset */
603 user
->idx
= log_first_idx
;
604 user
->seq
= log_first_seq
;
606 raw_spin_unlock_irq(&logbuf_lock
);
610 msg
= log_from_idx(user
->idx
);
611 ts_usec
= msg
->ts_nsec
;
612 do_div(ts_usec
, 1000);
615 * If we couldn't merge continuation line fragments during the print,
616 * export the stored flags to allow an optional external merge of the
617 * records. Merging the records isn't always neccessarily correct, like
618 * when we hit a race during printing. In most cases though, it produces
619 * better readable output. 'c' in the record flags mark the first
620 * fragment of a line, '+' the following.
622 if (msg
->flags
& LOG_CONT
&& !(user
->prev
& LOG_CONT
))
624 else if ((msg
->flags
& LOG_CONT
) ||
625 ((user
->prev
& LOG_CONT
) && !(msg
->flags
& LOG_PREFIX
)))
628 len
= sprintf(user
->buf
, "%u,%llu,%llu,%c;",
629 (msg
->facility
<< 3) | msg
->level
,
630 user
->seq
, ts_usec
, cont
);
631 user
->prev
= msg
->flags
;
633 /* escape non-printable characters */
634 for (i
= 0; i
< msg
->text_len
; i
++) {
635 unsigned char c
= log_text(msg
)[i
];
637 if (c
< ' ' || c
>= 127 || c
== '\\')
638 len
+= sprintf(user
->buf
+ len
, "\\x%02x", c
);
640 user
->buf
[len
++] = c
;
642 user
->buf
[len
++] = '\n';
647 for (i
= 0; i
< msg
->dict_len
; i
++) {
648 unsigned char c
= log_dict(msg
)[i
];
651 user
->buf
[len
++] = ' ';
656 user
->buf
[len
++] = '\n';
661 if (c
< ' ' || c
>= 127 || c
== '\\') {
662 len
+= sprintf(user
->buf
+ len
, "\\x%02x", c
);
666 user
->buf
[len
++] = c
;
668 user
->buf
[len
++] = '\n';
671 user
->idx
= log_next(user
->idx
);
673 raw_spin_unlock_irq(&logbuf_lock
);
680 if (copy_to_user(buf
, user
->buf
, len
)) {
686 mutex_unlock(&user
->lock
);
690 static loff_t
devkmsg_llseek(struct file
*file
, loff_t offset
, int whence
)
692 struct devkmsg_user
*user
= file
->private_data
;
700 raw_spin_lock_irq(&logbuf_lock
);
703 /* the first record */
704 user
->idx
= log_first_idx
;
705 user
->seq
= log_first_seq
;
709 * The first record after the last SYSLOG_ACTION_CLEAR,
710 * like issued by 'dmesg -c'. Reading /dev/kmsg itself
711 * changes no global state, and does not clear anything.
713 user
->idx
= clear_idx
;
714 user
->seq
= clear_seq
;
717 /* after the last record */
718 user
->idx
= log_next_idx
;
719 user
->seq
= log_next_seq
;
724 raw_spin_unlock_irq(&logbuf_lock
);
728 static unsigned int devkmsg_poll(struct file
*file
, poll_table
*wait
)
730 struct devkmsg_user
*user
= file
->private_data
;
734 return POLLERR
|POLLNVAL
;
736 poll_wait(file
, &log_wait
, wait
);
738 raw_spin_lock_irq(&logbuf_lock
);
739 if (user
->seq
< log_next_seq
) {
740 /* return error when data has vanished underneath us */
741 if (user
->seq
< log_first_seq
)
742 ret
= POLLIN
|POLLRDNORM
|POLLERR
|POLLPRI
;
744 ret
= POLLIN
|POLLRDNORM
;
746 raw_spin_unlock_irq(&logbuf_lock
);
751 static int devkmsg_open(struct inode
*inode
, struct file
*file
)
753 struct devkmsg_user
*user
;
756 /* write-only does not need any file context */
757 if ((file
->f_flags
& O_ACCMODE
) == O_WRONLY
)
760 err
= check_syslog_permissions(SYSLOG_ACTION_READ_ALL
,
765 user
= kmalloc(sizeof(struct devkmsg_user
), GFP_KERNEL
);
769 mutex_init(&user
->lock
);
771 raw_spin_lock_irq(&logbuf_lock
);
772 user
->idx
= log_first_idx
;
773 user
->seq
= log_first_seq
;
774 raw_spin_unlock_irq(&logbuf_lock
);
776 file
->private_data
= user
;
780 static int devkmsg_release(struct inode
*inode
, struct file
*file
)
782 struct devkmsg_user
*user
= file
->private_data
;
787 mutex_destroy(&user
->lock
);
792 const struct file_operations kmsg_fops
= {
793 .open
= devkmsg_open
,
794 .read
= devkmsg_read
,
795 .aio_write
= devkmsg_writev
,
796 .llseek
= devkmsg_llseek
,
797 .poll
= devkmsg_poll
,
798 .release
= devkmsg_release
,
803 * This appends the listed symbols to /proc/vmcore
805 * /proc/vmcore is used by various utilities, like crash and makedumpfile to
806 * obtain access to symbols that are otherwise very difficult to locate. These
807 * symbols are specifically used so that utilities can access and extract the
808 * dmesg log from a vmcore file after a crash.
810 void log_buf_kexec_setup(void)
812 VMCOREINFO_SYMBOL(log_buf
);
813 VMCOREINFO_SYMBOL(log_buf_len
);
814 VMCOREINFO_SYMBOL(log_first_idx
);
815 VMCOREINFO_SYMBOL(log_next_idx
);
817 * Export struct printk_log size and field offsets. User space tools can
818 * parse it and detect any changes to structure down the line.
820 VMCOREINFO_STRUCT_SIZE(printk_log
);
821 VMCOREINFO_OFFSET(printk_log
, ts_nsec
);
822 VMCOREINFO_OFFSET(printk_log
, len
);
823 VMCOREINFO_OFFSET(printk_log
, text_len
);
824 VMCOREINFO_OFFSET(printk_log
, dict_len
);
828 /* requested log_buf_len from kernel cmdline */
829 static unsigned long __initdata new_log_buf_len
;
831 /* save requested log_buf_len since it's too early to process it */
832 static int __init
log_buf_len_setup(char *str
)
834 unsigned size
= memparse(str
, &str
);
837 size
= roundup_pow_of_two(size
);
838 if (size
> log_buf_len
)
839 new_log_buf_len
= size
;
843 early_param("log_buf_len", log_buf_len_setup
);
845 void __init
setup_log_buf(int early
)
851 if (!new_log_buf_len
)
856 memblock_virt_alloc(new_log_buf_len
, PAGE_SIZE
);
858 new_log_buf
= memblock_virt_alloc_nopanic(new_log_buf_len
, 0);
861 if (unlikely(!new_log_buf
)) {
862 pr_err("log_buf_len: %ld bytes not available\n",
867 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
868 log_buf_len
= new_log_buf_len
;
869 log_buf
= new_log_buf
;
871 free
= __LOG_BUF_LEN
- log_next_idx
;
872 memcpy(log_buf
, __log_buf
, __LOG_BUF_LEN
);
873 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
875 pr_info("log_buf_len: %d\n", log_buf_len
);
876 pr_info("early log buf free: %d(%d%%)\n",
877 free
, (free
* 100) / __LOG_BUF_LEN
);
880 static bool __read_mostly ignore_loglevel
;
882 static int __init
ignore_loglevel_setup(char *str
)
885 pr_info("debug: ignoring loglevel setting.\n");
890 early_param("ignore_loglevel", ignore_loglevel_setup
);
891 module_param(ignore_loglevel
, bool, S_IRUGO
| S_IWUSR
);
892 MODULE_PARM_DESC(ignore_loglevel
, "ignore loglevel setting, to"
893 "print all kernel messages to the console.");
895 #ifdef CONFIG_BOOT_PRINTK_DELAY
897 static int boot_delay
; /* msecs delay after each printk during bootup */
898 static unsigned long long loops_per_msec
; /* based on boot_delay */
900 static int __init
boot_delay_setup(char *str
)
904 lpj
= preset_lpj
? preset_lpj
: 1000000; /* some guess */
905 loops_per_msec
= (unsigned long long)lpj
/ 1000 * HZ
;
907 get_option(&str
, &boot_delay
);
908 if (boot_delay
> 10 * 1000)
911 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
912 "HZ: %d, loops_per_msec: %llu\n",
913 boot_delay
, preset_lpj
, lpj
, HZ
, loops_per_msec
);
916 early_param("boot_delay", boot_delay_setup
);
918 static void boot_delay_msec(int level
)
920 unsigned long long k
;
921 unsigned long timeout
;
923 if ((boot_delay
== 0 || system_state
!= SYSTEM_BOOTING
)
924 || (level
>= console_loglevel
&& !ignore_loglevel
)) {
928 k
= (unsigned long long)loops_per_msec
* boot_delay
;
930 timeout
= jiffies
+ msecs_to_jiffies(boot_delay
);
935 * use (volatile) jiffies to prevent
936 * compiler reduction; loop termination via jiffies
937 * is secondary and may or may not happen.
939 if (time_after(jiffies
, timeout
))
941 touch_nmi_watchdog();
945 static inline void boot_delay_msec(int level
)
950 #if defined(CONFIG_PRINTK_TIME)
951 static bool printk_time
= 1;
953 static bool printk_time
;
955 module_param_named(time
, printk_time
, bool, S_IRUGO
| S_IWUSR
);
957 static size_t print_time(u64 ts
, char *buf
)
959 unsigned long rem_nsec
;
964 rem_nsec
= do_div(ts
, 1000000000);
967 return snprintf(NULL
, 0, "[%5lu.000000] ", (unsigned long)ts
);
969 return sprintf(buf
, "[%5lu.%06lu] ",
970 (unsigned long)ts
, rem_nsec
/ 1000);
973 static size_t print_prefix(const struct printk_log
*msg
, bool syslog
, char *buf
)
976 unsigned int prefix
= (msg
->facility
<< 3) | msg
->level
;
980 len
+= sprintf(buf
, "<%u>", prefix
);
985 else if (prefix
> 99)
992 len
+= print_time(msg
->ts_nsec
, buf
? buf
+ len
: NULL
);
996 static size_t msg_print_text(const struct printk_log
*msg
, enum log_flags prev
,
997 bool syslog
, char *buf
, size_t size
)
999 const char *text
= log_text(msg
);
1000 size_t text_size
= msg
->text_len
;
1002 bool newline
= true;
1005 if ((prev
& LOG_CONT
) && !(msg
->flags
& LOG_PREFIX
))
1008 if (msg
->flags
& LOG_CONT
) {
1009 if ((prev
& LOG_CONT
) && !(prev
& LOG_NEWLINE
))
1012 if (!(msg
->flags
& LOG_NEWLINE
))
1017 const char *next
= memchr(text
, '\n', text_size
);
1021 text_len
= next
- text
;
1023 text_size
-= next
- text
;
1025 text_len
= text_size
;
1029 if (print_prefix(msg
, syslog
, NULL
) +
1030 text_len
+ 1 >= size
- len
)
1034 len
+= print_prefix(msg
, syslog
, buf
+ len
);
1035 memcpy(buf
+ len
, text
, text_len
);
1037 if (next
|| newline
)
1040 /* SYSLOG_ACTION_* buffer size only calculation */
1042 len
+= print_prefix(msg
, syslog
, NULL
);
1044 if (next
|| newline
)
1055 static int syslog_print(char __user
*buf
, int size
)
1058 struct printk_log
*msg
;
1061 text
= kmalloc(LOG_LINE_MAX
+ PREFIX_MAX
, GFP_KERNEL
);
1069 raw_spin_lock_irq(&logbuf_lock
);
1070 if (syslog_seq
< log_first_seq
) {
1071 /* messages are gone, move to first one */
1072 syslog_seq
= log_first_seq
;
1073 syslog_idx
= log_first_idx
;
1077 if (syslog_seq
== log_next_seq
) {
1078 raw_spin_unlock_irq(&logbuf_lock
);
1082 skip
= syslog_partial
;
1083 msg
= log_from_idx(syslog_idx
);
1084 n
= msg_print_text(msg
, syslog_prev
, true, text
,
1085 LOG_LINE_MAX
+ PREFIX_MAX
);
1086 if (n
- syslog_partial
<= size
) {
1087 /* message fits into buffer, move forward */
1088 syslog_idx
= log_next(syslog_idx
);
1090 syslog_prev
= msg
->flags
;
1091 n
-= syslog_partial
;
1094 /* partial read(), remember position */
1096 syslog_partial
+= n
;
1099 raw_spin_unlock_irq(&logbuf_lock
);
1104 if (copy_to_user(buf
, text
+ skip
, n
)) {
1119 static int syslog_print_all(char __user
*buf
, int size
, bool clear
)
1124 text
= kmalloc(LOG_LINE_MAX
+ PREFIX_MAX
, GFP_KERNEL
);
1128 raw_spin_lock_irq(&logbuf_lock
);
1133 enum log_flags prev
;
1135 if (clear_seq
< log_first_seq
) {
1136 /* messages are gone, move to first available one */
1137 clear_seq
= log_first_seq
;
1138 clear_idx
= log_first_idx
;
1142 * Find first record that fits, including all following records,
1143 * into the user-provided buffer for this dump.
1148 while (seq
< log_next_seq
) {
1149 struct printk_log
*msg
= log_from_idx(idx
);
1151 len
+= msg_print_text(msg
, prev
, true, NULL
, 0);
1153 idx
= log_next(idx
);
1157 /* move first record forward until length fits into the buffer */
1161 while (len
> size
&& seq
< log_next_seq
) {
1162 struct printk_log
*msg
= log_from_idx(idx
);
1164 len
-= msg_print_text(msg
, prev
, true, NULL
, 0);
1166 idx
= log_next(idx
);
1170 /* last message fitting into this dump */
1171 next_seq
= log_next_seq
;
1174 while (len
>= 0 && seq
< next_seq
) {
1175 struct printk_log
*msg
= log_from_idx(idx
);
1178 textlen
= msg_print_text(msg
, prev
, true, text
,
1179 LOG_LINE_MAX
+ PREFIX_MAX
);
1184 idx
= log_next(idx
);
1188 raw_spin_unlock_irq(&logbuf_lock
);
1189 if (copy_to_user(buf
+ len
, text
, textlen
))
1193 raw_spin_lock_irq(&logbuf_lock
);
1195 if (seq
< log_first_seq
) {
1196 /* messages are gone, move to next one */
1197 seq
= log_first_seq
;
1198 idx
= log_first_idx
;
1205 clear_seq
= log_next_seq
;
1206 clear_idx
= log_next_idx
;
1208 raw_spin_unlock_irq(&logbuf_lock
);
1214 int do_syslog(int type
, char __user
*buf
, int len
, bool from_file
)
1217 static int saved_console_loglevel
= -1;
1220 error
= check_syslog_permissions(type
, from_file
);
1224 error
= security_syslog(type
);
1229 case SYSLOG_ACTION_CLOSE
: /* Close log */
1231 case SYSLOG_ACTION_OPEN
: /* Open log */
1233 case SYSLOG_ACTION_READ
: /* Read from log */
1235 if (!buf
|| len
< 0)
1240 if (!access_ok(VERIFY_WRITE
, buf
, len
)) {
1244 error
= wait_event_interruptible(log_wait
,
1245 syslog_seq
!= log_next_seq
);
1248 error
= syslog_print(buf
, len
);
1250 /* Read/clear last kernel messages */
1251 case SYSLOG_ACTION_READ_CLEAR
:
1254 /* Read last kernel messages */
1255 case SYSLOG_ACTION_READ_ALL
:
1257 if (!buf
|| len
< 0)
1262 if (!access_ok(VERIFY_WRITE
, buf
, len
)) {
1266 error
= syslog_print_all(buf
, len
, clear
);
1268 /* Clear ring buffer */
1269 case SYSLOG_ACTION_CLEAR
:
1270 syslog_print_all(NULL
, 0, true);
1272 /* Disable logging to console */
1273 case SYSLOG_ACTION_CONSOLE_OFF
:
1274 if (saved_console_loglevel
== -1)
1275 saved_console_loglevel
= console_loglevel
;
1276 console_loglevel
= minimum_console_loglevel
;
1278 /* Enable logging to console */
1279 case SYSLOG_ACTION_CONSOLE_ON
:
1280 if (saved_console_loglevel
!= -1) {
1281 console_loglevel
= saved_console_loglevel
;
1282 saved_console_loglevel
= -1;
1285 /* Set level of messages printed to console */
1286 case SYSLOG_ACTION_CONSOLE_LEVEL
:
1288 if (len
< 1 || len
> 8)
1290 if (len
< minimum_console_loglevel
)
1291 len
= minimum_console_loglevel
;
1292 console_loglevel
= len
;
1293 /* Implicitly re-enable logging to console */
1294 saved_console_loglevel
= -1;
1297 /* Number of chars in the log buffer */
1298 case SYSLOG_ACTION_SIZE_UNREAD
:
1299 raw_spin_lock_irq(&logbuf_lock
);
1300 if (syslog_seq
< log_first_seq
) {
1301 /* messages are gone, move to first one */
1302 syslog_seq
= log_first_seq
;
1303 syslog_idx
= log_first_idx
;
1309 * Short-cut for poll(/"proc/kmsg") which simply checks
1310 * for pending data, not the size; return the count of
1311 * records, not the length.
1313 error
= log_next_idx
- syslog_idx
;
1315 u64 seq
= syslog_seq
;
1316 u32 idx
= syslog_idx
;
1317 enum log_flags prev
= syslog_prev
;
1320 while (seq
< log_next_seq
) {
1321 struct printk_log
*msg
= log_from_idx(idx
);
1323 error
+= msg_print_text(msg
, prev
, true, NULL
, 0);
1324 idx
= log_next(idx
);
1328 error
-= syslog_partial
;
1330 raw_spin_unlock_irq(&logbuf_lock
);
1332 /* Size of the log buffer */
1333 case SYSLOG_ACTION_SIZE_BUFFER
:
1334 error
= log_buf_len
;
1344 SYSCALL_DEFINE3(syslog
, int, type
, char __user
*, buf
, int, len
)
1346 return do_syslog(type
, buf
, len
, SYSLOG_FROM_READER
);
1350 * Call the console drivers, asking them to write out
1351 * log_buf[start] to log_buf[end - 1].
1352 * The console_lock must be held.
1354 static void call_console_drivers(int level
, const char *text
, size_t len
)
1356 struct console
*con
;
1358 trace_console(text
, len
);
1360 if (level
>= console_loglevel
&& !ignore_loglevel
)
1362 if (!console_drivers
)
1365 for_each_console(con
) {
1366 if (exclusive_console
&& con
!= exclusive_console
)
1368 if (!(con
->flags
& CON_ENABLED
))
1372 if (!cpu_online(smp_processor_id()) &&
1373 !(con
->flags
& CON_ANYTIME
))
1375 con
->write(con
, text
, len
);
1380 * Zap console related locks when oopsing. Only zap at most once
1381 * every 10 seconds, to leave time for slow consoles to print a
1384 static void zap_locks(void)
1386 static unsigned long oops_timestamp
;
1388 if (time_after_eq(jiffies
, oops_timestamp
) &&
1389 !time_after(jiffies
, oops_timestamp
+ 30 * HZ
))
1392 oops_timestamp
= jiffies
;
1395 /* If a crash is occurring, make sure we can't deadlock */
1396 raw_spin_lock_init(&logbuf_lock
);
1397 /* And make sure that we print immediately */
1398 sema_init(&console_sem
, 1);
1402 * Check if we have any console that is capable of printing while cpu is
1403 * booting or shutting down. Requires console_sem.
1405 static int have_callable_console(void)
1407 struct console
*con
;
1409 for_each_console(con
)
1410 if (con
->flags
& CON_ANYTIME
)
1417 * Can we actually use the console at this time on this cpu?
1419 * Console drivers may assume that per-cpu resources have been allocated. So
1420 * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
1421 * call them until this CPU is officially up.
1423 static inline int can_use_console(unsigned int cpu
)
1425 return cpu_online(cpu
) || have_callable_console();
1429 * Try to get console ownership to actually show the kernel
1430 * messages from a 'printk'. Return true (and with the
1431 * console_lock held, and 'console_locked' set) if it
1432 * is successful, false otherwise.
1434 static int console_trylock_for_printk(void)
1436 unsigned int cpu
= smp_processor_id();
1438 if (!console_trylock())
1441 * If we can't use the console, we need to release the console
1442 * semaphore by hand to avoid flushing the buffer. We need to hold the
1443 * console semaphore in order to do this test safely.
1445 if (!can_use_console(cpu
)) {
1453 int printk_delay_msec __read_mostly
;
1455 static inline void printk_delay(void)
1457 if (unlikely(printk_delay_msec
)) {
1458 int m
= printk_delay_msec
;
1462 touch_nmi_watchdog();
1468 * Continuation lines are buffered, and not committed to the record buffer
1469 * until the line is complete, or a race forces it. The line fragments
1470 * though, are printed immediately to the consoles to ensure everything has
1471 * reached the console in case of a kernel crash.
1473 static struct cont
{
1474 char buf
[LOG_LINE_MAX
];
1475 size_t len
; /* length == 0 means unused buffer */
1476 size_t cons
; /* bytes written to console */
1477 struct task_struct
*owner
; /* task of first print*/
1478 u64 ts_nsec
; /* time of first print */
1479 u8 level
; /* log level of first message */
1480 u8 facility
; /* log level of first message */
1481 enum log_flags flags
; /* prefix, newline flags */
1482 bool flushed
:1; /* buffer sealed and committed */
1485 static void cont_flush(enum log_flags flags
)
1494 * If a fragment of this line was directly flushed to the
1495 * console; wait for the console to pick up the rest of the
1496 * line. LOG_NOCONS suppresses a duplicated output.
1498 log_store(cont
.facility
, cont
.level
, flags
| LOG_NOCONS
,
1499 cont
.ts_nsec
, NULL
, 0, cont
.buf
, cont
.len
);
1501 cont
.flushed
= true;
1504 * If no fragment of this line ever reached the console,
1505 * just submit it to the store and free the buffer.
1507 log_store(cont
.facility
, cont
.level
, flags
, 0,
1508 NULL
, 0, cont
.buf
, cont
.len
);
1513 static bool cont_add(int facility
, int level
, const char *text
, size_t len
)
1515 if (cont
.len
&& cont
.flushed
)
1518 if (cont
.len
+ len
> sizeof(cont
.buf
)) {
1519 /* the line gets too long, split it up in separate records */
1520 cont_flush(LOG_CONT
);
1525 cont
.facility
= facility
;
1527 cont
.owner
= current
;
1528 cont
.ts_nsec
= local_clock();
1531 cont
.flushed
= false;
1534 memcpy(cont
.buf
+ cont
.len
, text
, len
);
1537 if (cont
.len
> (sizeof(cont
.buf
) * 80) / 100)
1538 cont_flush(LOG_CONT
);
1543 static size_t cont_print_text(char *text
, size_t size
)
1548 if (cont
.cons
== 0 && (console_prev
& LOG_NEWLINE
)) {
1549 textlen
+= print_time(cont
.ts_nsec
, text
);
1553 len
= cont
.len
- cont
.cons
;
1557 memcpy(text
+ textlen
, cont
.buf
+ cont
.cons
, len
);
1559 cont
.cons
= cont
.len
;
1563 if (cont
.flags
& LOG_NEWLINE
)
1564 text
[textlen
++] = '\n';
1565 /* got everything, release buffer */
1571 asmlinkage
int vprintk_emit(int facility
, int level
,
1572 const char *dict
, size_t dictlen
,
1573 const char *fmt
, va_list args
)
1575 static int recursion_bug
;
1576 static char textbuf
[LOG_LINE_MAX
];
1577 char *text
= textbuf
;
1578 size_t text_len
= 0;
1579 enum log_flags lflags
= 0;
1580 unsigned long flags
;
1582 int printed_len
= 0;
1583 bool in_sched
= false;
1584 /* cpu currently holding logbuf_lock in this function */
1585 static volatile unsigned int logbuf_cpu
= UINT_MAX
;
1587 if (level
== SCHED_MESSAGE_LOGLEVEL
) {
1592 boot_delay_msec(level
);
1595 /* This stops the holder of console_sem just where we want him */
1596 local_irq_save(flags
);
1597 this_cpu
= smp_processor_id();
1600 * Ouch, printk recursed into itself!
1602 if (unlikely(logbuf_cpu
== this_cpu
)) {
1604 * If a crash is occurring during printk() on this CPU,
1605 * then try to get the crash message out but make sure
1606 * we can't deadlock. Otherwise just return to avoid the
1607 * recursion and return - but flag the recursion so that
1608 * it can be printed at the next appropriate moment:
1610 if (!oops_in_progress
&& !lockdep_recursing(current
)) {
1612 local_irq_restore(flags
);
1619 raw_spin_lock(&logbuf_lock
);
1620 logbuf_cpu
= this_cpu
;
1622 if (recursion_bug
) {
1623 static const char recursion_msg
[] =
1624 "BUG: recent printk recursion!";
1627 text_len
= strlen(recursion_msg
);
1628 /* emit KERN_CRIT message */
1629 printed_len
+= log_store(0, 2, LOG_PREFIX
|LOG_NEWLINE
, 0,
1630 NULL
, 0, recursion_msg
, text_len
);
1634 * The printf needs to come first; we need the syslog
1635 * prefix which might be passed-in as a parameter.
1638 text_len
= scnprintf(text
, sizeof(textbuf
),
1639 KERN_WARNING
"[sched_delayed] ");
1641 text_len
+= vscnprintf(text
+ text_len
,
1642 sizeof(textbuf
) - text_len
, fmt
, args
);
1644 /* mark and strip a trailing newline */
1645 if (text_len
&& text
[text_len
-1] == '\n') {
1647 lflags
|= LOG_NEWLINE
;
1650 /* strip kernel syslog prefix and extract log level or control flags */
1651 if (facility
== 0) {
1652 int kern_level
= printk_get_level(text
);
1655 const char *end_of_header
= printk_skip_level(text
);
1656 switch (kern_level
) {
1659 level
= kern_level
- '0';
1660 case 'd': /* KERN_DEFAULT */
1661 lflags
|= LOG_PREFIX
;
1664 * No need to check length here because vscnprintf
1665 * put '\0' at the end of the string. Only valid and
1666 * newly printed level is detected.
1668 text_len
-= end_of_header
- text
;
1669 text
= (char *)end_of_header
;
1674 level
= default_message_loglevel
;
1677 lflags
|= LOG_PREFIX
|LOG_NEWLINE
;
1679 if (!(lflags
& LOG_NEWLINE
)) {
1681 * Flush the conflicting buffer. An earlier newline was missing,
1682 * or another task also prints continuation lines.
1684 if (cont
.len
&& (lflags
& LOG_PREFIX
|| cont
.owner
!= current
))
1685 cont_flush(LOG_NEWLINE
);
1687 /* buffer line if possible, otherwise store it right away */
1688 if (cont_add(facility
, level
, text
, text_len
))
1689 printed_len
+= text_len
;
1691 printed_len
+= log_store(facility
, level
,
1692 lflags
| LOG_CONT
, 0,
1693 dict
, dictlen
, text
, text_len
);
1695 bool stored
= false;
1698 * If an earlier newline was missing and it was the same task,
1699 * either merge it with the current buffer and flush, or if
1700 * there was a race with interrupts (prefix == true) then just
1701 * flush it out and store this line separately.
1702 * If the preceding printk was from a different task and missed
1703 * a newline, flush and append the newline.
1706 if (cont
.owner
== current
&& !(lflags
& LOG_PREFIX
))
1707 stored
= cont_add(facility
, level
, text
,
1709 cont_flush(LOG_NEWLINE
);
1713 printed_len
+= text_len
;
1715 printed_len
+= log_store(facility
, level
, lflags
, 0,
1716 dict
, dictlen
, text
, text_len
);
1719 logbuf_cpu
= UINT_MAX
;
1720 raw_spin_unlock(&logbuf_lock
);
1722 local_irq_restore(flags
);
1724 /* If called from the scheduler, we can not call up(). */
1729 * Disable preemption to avoid being preempted while holding
1730 * console_sem which would prevent anyone from printing to console
1734 * Try to acquire and then immediately release the console semaphore.
1735 * The release will print out buffers and wake up /dev/kmsg and syslog()
1738 if (console_trylock_for_printk())
1744 EXPORT_SYMBOL(vprintk_emit
);
1746 asmlinkage
int vprintk(const char *fmt
, va_list args
)
1748 return vprintk_emit(0, -1, NULL
, 0, fmt
, args
);
1750 EXPORT_SYMBOL(vprintk
);
1752 asmlinkage
int printk_emit(int facility
, int level
,
1753 const char *dict
, size_t dictlen
,
1754 const char *fmt
, ...)
1759 va_start(args
, fmt
);
1760 r
= vprintk_emit(facility
, level
, dict
, dictlen
, fmt
, args
);
1765 EXPORT_SYMBOL(printk_emit
);
1768 * printk - print a kernel message
1769 * @fmt: format string
1771 * This is printk(). It can be called from any context. We want it to work.
1773 * We try to grab the console_lock. If we succeed, it's easy - we log the
1774 * output and call the console drivers. If we fail to get the semaphore, we
1775 * place the output into the log buffer and return. The current holder of
1776 * the console_sem will notice the new output in console_unlock(); and will
1777 * send it to the consoles before releasing the lock.
1779 * One effect of this deferred printing is that code which calls printk() and
1780 * then changes console_loglevel may break. This is because console_loglevel
1781 * is inspected when the actual printing occurs.
1786 * See the vsnprintf() documentation for format string extensions over C99.
1788 asmlinkage __visible
int printk(const char *fmt
, ...)
1793 #ifdef CONFIG_KGDB_KDB
1794 if (unlikely(kdb_trap_printk
)) {
1795 va_start(args
, fmt
);
1796 r
= vkdb_printf(fmt
, args
);
1801 va_start(args
, fmt
);
1802 r
= vprintk_emit(0, -1, NULL
, 0, fmt
, args
);
1807 EXPORT_SYMBOL(printk
);
1809 #else /* CONFIG_PRINTK */
1811 #define LOG_LINE_MAX 0
1812 #define PREFIX_MAX 0
1813 #define LOG_LINE_MAX 0
1814 static u64 syslog_seq
;
1815 static u32 syslog_idx
;
1816 static u64 console_seq
;
1817 static u32 console_idx
;
1818 static enum log_flags syslog_prev
;
1819 static u64 log_first_seq
;
1820 static u32 log_first_idx
;
1821 static u64 log_next_seq
;
1822 static enum log_flags console_prev
;
1823 static struct cont
{
1829 static struct printk_log
*log_from_idx(u32 idx
) { return NULL
; }
1830 static u32
log_next(u32 idx
) { return 0; }
1831 static void call_console_drivers(int level
, const char *text
, size_t len
) {}
1832 static size_t msg_print_text(const struct printk_log
*msg
, enum log_flags prev
,
1833 bool syslog
, char *buf
, size_t size
) { return 0; }
1834 static size_t cont_print_text(char *text
, size_t size
) { return 0; }
1836 #endif /* CONFIG_PRINTK */
1838 #ifdef CONFIG_EARLY_PRINTK
1839 struct console
*early_console
;
1841 void early_vprintk(const char *fmt
, va_list ap
)
1843 if (early_console
) {
1845 int n
= vscnprintf(buf
, sizeof(buf
), fmt
, ap
);
1847 early_console
->write(early_console
, buf
, n
);
1851 asmlinkage __visible
void early_printk(const char *fmt
, ...)
1856 early_vprintk(fmt
, ap
);
1861 static int __add_preferred_console(char *name
, int idx
, char *options
,
1864 struct console_cmdline
*c
;
1868 * See if this tty is not yet registered, and
1869 * if we have a slot free.
1871 for (i
= 0, c
= console_cmdline
;
1872 i
< MAX_CMDLINECONSOLES
&& c
->name
[0];
1874 if (strcmp(c
->name
, name
) == 0 && c
->index
== idx
) {
1876 selected_console
= i
;
1880 if (i
== MAX_CMDLINECONSOLES
)
1883 selected_console
= i
;
1884 strlcpy(c
->name
, name
, sizeof(c
->name
));
1885 c
->options
= options
;
1886 braille_set_options(c
, brl_options
);
1892 * Set up a list of consoles. Called from init/main.c
1894 static int __init
console_setup(char *str
)
1896 char buf
[sizeof(console_cmdline
[0].name
) + 4]; /* 4 for index */
1897 char *s
, *options
, *brl_options
= NULL
;
1900 if (_braille_console_setup(&str
, &brl_options
))
1904 * Decode str into name, index, options.
1906 if (str
[0] >= '0' && str
[0] <= '9') {
1907 strcpy(buf
, "ttyS");
1908 strncpy(buf
+ 4, str
, sizeof(buf
) - 5);
1910 strncpy(buf
, str
, sizeof(buf
) - 1);
1912 buf
[sizeof(buf
) - 1] = 0;
1913 if ((options
= strchr(str
, ',')) != NULL
)
1916 if (!strcmp(str
, "ttya"))
1917 strcpy(buf
, "ttyS0");
1918 if (!strcmp(str
, "ttyb"))
1919 strcpy(buf
, "ttyS1");
1921 for (s
= buf
; *s
; s
++)
1922 if ((*s
>= '0' && *s
<= '9') || *s
== ',')
1924 idx
= simple_strtoul(s
, NULL
, 10);
1927 __add_preferred_console(buf
, idx
, options
, brl_options
);
1928 console_set_on_cmdline
= 1;
1931 __setup("console=", console_setup
);
1934 * add_preferred_console - add a device to the list of preferred consoles.
1935 * @name: device name
1936 * @idx: device index
1937 * @options: options for this console
1939 * The last preferred console added will be used for kernel messages
1940 * and stdin/out/err for init. Normally this is used by console_setup
1941 * above to handle user-supplied console arguments; however it can also
1942 * be used by arch-specific code either to override the user or more
1943 * commonly to provide a default console (ie from PROM variables) when
1944 * the user has not supplied one.
1946 int add_preferred_console(char *name
, int idx
, char *options
)
1948 return __add_preferred_console(name
, idx
, options
, NULL
);
1951 int update_console_cmdline(char *name
, int idx
, char *name_new
, int idx_new
, char *options
)
1953 struct console_cmdline
*c
;
1956 for (i
= 0, c
= console_cmdline
;
1957 i
< MAX_CMDLINECONSOLES
&& c
->name
[0];
1959 if (strcmp(c
->name
, name
) == 0 && c
->index
== idx
) {
1960 strlcpy(c
->name
, name_new
, sizeof(c
->name
));
1961 c
->name
[sizeof(c
->name
) - 1] = 0;
1962 c
->options
= options
;
1970 bool console_suspend_enabled
= 1;
1971 EXPORT_SYMBOL(console_suspend_enabled
);
1973 static int __init
console_suspend_disable(char *str
)
1975 console_suspend_enabled
= 0;
1978 __setup("no_console_suspend", console_suspend_disable
);
1979 module_param_named(console_suspend
, console_suspend_enabled
,
1980 bool, S_IRUGO
| S_IWUSR
);
1981 MODULE_PARM_DESC(console_suspend
, "suspend console during suspend"
1982 " and hibernate operations");
1985 * suspend_console - suspend the console subsystem
1987 * This disables printk() while we go into suspend states
1989 void suspend_console(void)
1991 if (!console_suspend_enabled
)
1993 printk("Suspending console(s) (use no_console_suspend to debug)\n");
1995 console_suspended
= 1;
1999 void resume_console(void)
2001 if (!console_suspend_enabled
)
2004 console_suspended
= 0;
2009 * console_cpu_notify - print deferred console messages after CPU hotplug
2010 * @self: notifier struct
2011 * @action: CPU hotplug event
2014 * If printk() is called from a CPU that is not online yet, the messages
2015 * will be spooled but will not show up on the console. This function is
2016 * called when a new CPU comes online (or fails to come up), and ensures
2017 * that any such output gets printed.
2019 static int console_cpu_notify(struct notifier_block
*self
,
2020 unsigned long action
, void *hcpu
)
2025 case CPU_DOWN_FAILED
:
2026 case CPU_UP_CANCELED
:
2034 * console_lock - lock the console system for exclusive use.
2036 * Acquires a lock which guarantees that the caller has
2037 * exclusive access to the console system and the console_drivers list.
2039 * Can sleep, returns nothing.
2041 void console_lock(void)
2046 if (console_suspended
)
2049 console_may_schedule
= 1;
2051 EXPORT_SYMBOL(console_lock
);
2054 * console_trylock - try to lock the console system for exclusive use.
2056 * Tried to acquire a lock which guarantees that the caller has
2057 * exclusive access to the console system and the console_drivers list.
2059 * returns 1 on success, and 0 on failure to acquire the lock.
2061 int console_trylock(void)
2063 if (down_trylock_console_sem())
2065 if (console_suspended
) {
2070 console_may_schedule
= 0;
2073 EXPORT_SYMBOL(console_trylock
);
2075 int is_console_locked(void)
2077 return console_locked
;
2080 static void console_cont_flush(char *text
, size_t size
)
2082 unsigned long flags
;
2085 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2091 * We still queue earlier records, likely because the console was
2092 * busy. The earlier ones need to be printed before this one, we
2093 * did not flush any fragment so far, so just let it queue up.
2095 if (console_seq
< log_next_seq
&& !cont
.cons
)
2098 len
= cont_print_text(text
, size
);
2099 raw_spin_unlock(&logbuf_lock
);
2100 stop_critical_timings();
2101 call_console_drivers(cont
.level
, text
, len
);
2102 start_critical_timings();
2103 local_irq_restore(flags
);
2106 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2110 * console_unlock - unlock the console system
2112 * Releases the console_lock which the caller holds on the console system
2113 * and the console driver list.
2115 * While the console_lock was held, console output may have been buffered
2116 * by printk(). If this is the case, console_unlock(); emits
2117 * the output prior to releasing the lock.
2119 * If there is output waiting, we wake /dev/kmsg and syslog() users.
2121 * console_unlock(); may be called from any context.
2123 void console_unlock(void)
2125 static char text
[LOG_LINE_MAX
+ PREFIX_MAX
];
2126 static u64 seen_seq
;
2127 unsigned long flags
;
2128 bool wake_klogd
= false;
2131 if (console_suspended
) {
2136 console_may_schedule
= 0;
2138 /* flush buffered message fragment immediately to console */
2139 console_cont_flush(text
, sizeof(text
));
2142 struct printk_log
*msg
;
2146 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2147 if (seen_seq
!= log_next_seq
) {
2149 seen_seq
= log_next_seq
;
2152 if (console_seq
< log_first_seq
) {
2153 len
= sprintf(text
, "** %u printk messages dropped ** ",
2154 (unsigned)(log_first_seq
- console_seq
));
2156 /* messages are gone, move to first one */
2157 console_seq
= log_first_seq
;
2158 console_idx
= log_first_idx
;
2164 if (console_seq
== log_next_seq
)
2167 msg
= log_from_idx(console_idx
);
2168 if (msg
->flags
& LOG_NOCONS
) {
2170 * Skip record we have buffered and already printed
2171 * directly to the console when we received it.
2173 console_idx
= log_next(console_idx
);
2176 * We will get here again when we register a new
2177 * CON_PRINTBUFFER console. Clear the flag so we
2178 * will properly dump everything later.
2180 msg
->flags
&= ~LOG_NOCONS
;
2181 console_prev
= msg
->flags
;
2186 len
+= msg_print_text(msg
, console_prev
, false,
2187 text
+ len
, sizeof(text
) - len
);
2188 console_idx
= log_next(console_idx
);
2190 console_prev
= msg
->flags
;
2191 raw_spin_unlock(&logbuf_lock
);
2193 stop_critical_timings(); /* don't trace print latency */
2194 call_console_drivers(level
, text
, len
);
2195 start_critical_timings();
2196 local_irq_restore(flags
);
2200 /* Release the exclusive_console once it is used */
2201 if (unlikely(exclusive_console
))
2202 exclusive_console
= NULL
;
2204 raw_spin_unlock(&logbuf_lock
);
2209 * Someone could have filled up the buffer again, so re-check if there's
2210 * something to flush. In case we cannot trylock the console_sem again,
2211 * there's a new owner and the console_unlock() from them will do the
2212 * flush, no worries.
2214 raw_spin_lock(&logbuf_lock
);
2215 retry
= console_seq
!= log_next_seq
;
2216 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2218 if (retry
&& console_trylock())
2224 EXPORT_SYMBOL(console_unlock
);
2227 * console_conditional_schedule - yield the CPU if required
2229 * If the console code is currently allowed to sleep, and
2230 * if this CPU should yield the CPU to another task, do
2233 * Must be called within console_lock();.
2235 void __sched
console_conditional_schedule(void)
2237 if (console_may_schedule
)
2240 EXPORT_SYMBOL(console_conditional_schedule
);
2242 void console_unblank(void)
2247 * console_unblank can no longer be called in interrupt context unless
2248 * oops_in_progress is set to 1..
2250 if (oops_in_progress
) {
2251 if (down_trylock_console_sem() != 0)
2257 console_may_schedule
= 0;
2259 if ((c
->flags
& CON_ENABLED
) && c
->unblank
)
2265 * Return the console tty driver structure and its associated index
2267 struct tty_driver
*console_device(int *index
)
2270 struct tty_driver
*driver
= NULL
;
2273 for_each_console(c
) {
2276 driver
= c
->device(c
, index
);
2285 * Prevent further output on the passed console device so that (for example)
2286 * serial drivers can disable console output before suspending a port, and can
2287 * re-enable output afterwards.
2289 void console_stop(struct console
*console
)
2292 console
->flags
&= ~CON_ENABLED
;
2295 EXPORT_SYMBOL(console_stop
);
2297 void console_start(struct console
*console
)
2300 console
->flags
|= CON_ENABLED
;
2303 EXPORT_SYMBOL(console_start
);
2305 static int __read_mostly keep_bootcon
;
2307 static int __init
keep_bootcon_setup(char *str
)
2310 pr_info("debug: skip boot console de-registration.\n");
2315 early_param("keep_bootcon", keep_bootcon_setup
);
2318 * The console driver calls this routine during kernel initialization
2319 * to register the console printing procedure with printk() and to
2320 * print any messages that were printed by the kernel before the
2321 * console driver was initialized.
2323 * This can happen pretty early during the boot process (because of
2324 * early_printk) - sometimes before setup_arch() completes - be careful
2325 * of what kernel features are used - they may not be initialised yet.
2327 * There are two types of consoles - bootconsoles (early_printk) and
2328 * "real" consoles (everything which is not a bootconsole) which are
2329 * handled differently.
2330 * - Any number of bootconsoles can be registered at any time.
2331 * - As soon as a "real" console is registered, all bootconsoles
2332 * will be unregistered automatically.
2333 * - Once a "real" console is registered, any attempt to register a
2334 * bootconsoles will be rejected
2336 void register_console(struct console
*newcon
)
2339 unsigned long flags
;
2340 struct console
*bcon
= NULL
;
2341 struct console_cmdline
*c
;
2343 if (console_drivers
)
2344 for_each_console(bcon
)
2345 if (WARN(bcon
== newcon
,
2346 "console '%s%d' already registered\n",
2347 bcon
->name
, bcon
->index
))
2351 * before we register a new CON_BOOT console, make sure we don't
2352 * already have a valid console
2354 if (console_drivers
&& newcon
->flags
& CON_BOOT
) {
2355 /* find the last or real console */
2356 for_each_console(bcon
) {
2357 if (!(bcon
->flags
& CON_BOOT
)) {
2358 pr_info("Too late to register bootconsole %s%d\n",
2359 newcon
->name
, newcon
->index
);
2365 if (console_drivers
&& console_drivers
->flags
& CON_BOOT
)
2366 bcon
= console_drivers
;
2368 if (preferred_console
< 0 || bcon
|| !console_drivers
)
2369 preferred_console
= selected_console
;
2371 if (newcon
->early_setup
)
2372 newcon
->early_setup();
2375 * See if we want to use this console driver. If we
2376 * didn't select a console we take the first one
2377 * that registers here.
2379 if (preferred_console
< 0) {
2380 if (newcon
->index
< 0)
2382 if (newcon
->setup
== NULL
||
2383 newcon
->setup(newcon
, NULL
) == 0) {
2384 newcon
->flags
|= CON_ENABLED
;
2385 if (newcon
->device
) {
2386 newcon
->flags
|= CON_CONSDEV
;
2387 preferred_console
= 0;
2393 * See if this console matches one we selected on
2396 for (i
= 0, c
= console_cmdline
;
2397 i
< MAX_CMDLINECONSOLES
&& c
->name
[0];
2399 if (strcmp(c
->name
, newcon
->name
) != 0)
2401 if (newcon
->index
>= 0 &&
2402 newcon
->index
!= c
->index
)
2404 if (newcon
->index
< 0)
2405 newcon
->index
= c
->index
;
2407 if (_braille_register_console(newcon
, c
))
2410 if (newcon
->setup
&&
2411 newcon
->setup(newcon
, console_cmdline
[i
].options
) != 0)
2413 newcon
->flags
|= CON_ENABLED
;
2414 newcon
->index
= c
->index
;
2415 if (i
== selected_console
) {
2416 newcon
->flags
|= CON_CONSDEV
;
2417 preferred_console
= selected_console
;
2422 if (!(newcon
->flags
& CON_ENABLED
))
2426 * If we have a bootconsole, and are switching to a real console,
2427 * don't print everything out again, since when the boot console, and
2428 * the real console are the same physical device, it's annoying to
2429 * see the beginning boot messages twice
2431 if (bcon
&& ((newcon
->flags
& (CON_CONSDEV
| CON_BOOT
)) == CON_CONSDEV
))
2432 newcon
->flags
&= ~CON_PRINTBUFFER
;
2435 * Put this console in the list - keep the
2436 * preferred driver at the head of the list.
2439 if ((newcon
->flags
& CON_CONSDEV
) || console_drivers
== NULL
) {
2440 newcon
->next
= console_drivers
;
2441 console_drivers
= newcon
;
2443 newcon
->next
->flags
&= ~CON_CONSDEV
;
2445 newcon
->next
= console_drivers
->next
;
2446 console_drivers
->next
= newcon
;
2448 if (newcon
->flags
& CON_PRINTBUFFER
) {
2450 * console_unlock(); will print out the buffered messages
2453 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2454 console_seq
= syslog_seq
;
2455 console_idx
= syslog_idx
;
2456 console_prev
= syslog_prev
;
2457 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2459 * We're about to replay the log buffer. Only do this to the
2460 * just-registered console to avoid excessive message spam to
2461 * the already-registered consoles.
2463 exclusive_console
= newcon
;
2466 console_sysfs_notify();
2469 * By unregistering the bootconsoles after we enable the real console
2470 * we get the "console xxx enabled" message on all the consoles -
2471 * boot consoles, real consoles, etc - this is to ensure that end
2472 * users know there might be something in the kernel's log buffer that
2473 * went to the bootconsole (that they do not see on the real console)
2475 pr_info("%sconsole [%s%d] enabled\n",
2476 (newcon
->flags
& CON_BOOT
) ? "boot" : "" ,
2477 newcon
->name
, newcon
->index
);
2479 ((newcon
->flags
& (CON_CONSDEV
| CON_BOOT
)) == CON_CONSDEV
) &&
2481 /* We need to iterate through all boot consoles, to make
2482 * sure we print everything out, before we unregister them.
2484 for_each_console(bcon
)
2485 if (bcon
->flags
& CON_BOOT
)
2486 unregister_console(bcon
);
2489 EXPORT_SYMBOL(register_console
);
2491 int unregister_console(struct console
*console
)
2493 struct console
*a
, *b
;
2496 pr_info("%sconsole [%s%d] disabled\n",
2497 (console
->flags
& CON_BOOT
) ? "boot" : "" ,
2498 console
->name
, console
->index
);
2500 res
= _braille_unregister_console(console
);
2506 if (console_drivers
== console
) {
2507 console_drivers
=console
->next
;
2509 } else if (console_drivers
) {
2510 for (a
=console_drivers
->next
, b
=console_drivers
;
2511 a
; b
=a
, a
=b
->next
) {
2521 * If this isn't the last console and it has CON_CONSDEV set, we
2522 * need to set it on the next preferred console.
2524 if (console_drivers
!= NULL
&& console
->flags
& CON_CONSDEV
)
2525 console_drivers
->flags
|= CON_CONSDEV
;
2527 console
->flags
&= ~CON_ENABLED
;
2529 console_sysfs_notify();
2532 EXPORT_SYMBOL(unregister_console
);
2534 static int __init
printk_late_init(void)
2536 struct console
*con
;
2538 for_each_console(con
) {
2539 if (!keep_bootcon
&& con
->flags
& CON_BOOT
) {
2540 unregister_console(con
);
2543 hotcpu_notifier(console_cpu_notify
, 0);
2546 late_initcall(printk_late_init
);
2548 #if defined CONFIG_PRINTK
2550 * Delayed printk version, for scheduler-internal messages:
2552 #define PRINTK_PENDING_WAKEUP 0x01
2553 #define PRINTK_PENDING_OUTPUT 0x02
2555 static DEFINE_PER_CPU(int, printk_pending
);
2557 static void wake_up_klogd_work_func(struct irq_work
*irq_work
)
2559 int pending
= __this_cpu_xchg(printk_pending
, 0);
2561 if (pending
& PRINTK_PENDING_OUTPUT
) {
2562 /* If trylock fails, someone else is doing the printing */
2563 if (console_trylock())
2567 if (pending
& PRINTK_PENDING_WAKEUP
)
2568 wake_up_interruptible(&log_wait
);
2571 static DEFINE_PER_CPU(struct irq_work
, wake_up_klogd_work
) = {
2572 .func
= wake_up_klogd_work_func
,
2573 .flags
= IRQ_WORK_LAZY
,
2576 void wake_up_klogd(void)
2579 if (waitqueue_active(&log_wait
)) {
2580 this_cpu_or(printk_pending
, PRINTK_PENDING_WAKEUP
);
2581 irq_work_queue(&__get_cpu_var(wake_up_klogd_work
));
2586 int printk_deferred(const char *fmt
, ...)
2592 va_start(args
, fmt
);
2593 r
= vprintk_emit(0, SCHED_MESSAGE_LOGLEVEL
, NULL
, 0, fmt
, args
);
2596 __this_cpu_or(printk_pending
, PRINTK_PENDING_OUTPUT
);
2597 irq_work_queue(&__get_cpu_var(wake_up_klogd_work
));
2604 * printk rate limiting, lifted from the networking subsystem.
2606 * This enforces a rate limit: not more than 10 kernel messages
2607 * every 5s to make a denial-of-service attack impossible.
2609 DEFINE_RATELIMIT_STATE(printk_ratelimit_state
, 5 * HZ
, 10);
2611 int __printk_ratelimit(const char *func
)
2613 return ___ratelimit(&printk_ratelimit_state
, func
);
2615 EXPORT_SYMBOL(__printk_ratelimit
);
2618 * printk_timed_ratelimit - caller-controlled printk ratelimiting
2619 * @caller_jiffies: pointer to caller's state
2620 * @interval_msecs: minimum interval between prints
2622 * printk_timed_ratelimit() returns true if more than @interval_msecs
2623 * milliseconds have elapsed since the last time printk_timed_ratelimit()
2626 bool printk_timed_ratelimit(unsigned long *caller_jiffies
,
2627 unsigned int interval_msecs
)
2629 if (*caller_jiffies
== 0
2630 || !time_in_range(jiffies
, *caller_jiffies
,
2632 + msecs_to_jiffies(interval_msecs
))) {
2633 *caller_jiffies
= jiffies
;
2638 EXPORT_SYMBOL(printk_timed_ratelimit
);
2640 static DEFINE_SPINLOCK(dump_list_lock
);
2641 static LIST_HEAD(dump_list
);
2644 * kmsg_dump_register - register a kernel log dumper.
2645 * @dumper: pointer to the kmsg_dumper structure
2647 * Adds a kernel log dumper to the system. The dump callback in the
2648 * structure will be called when the kernel oopses or panics and must be
2649 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
2651 int kmsg_dump_register(struct kmsg_dumper
*dumper
)
2653 unsigned long flags
;
2656 /* The dump callback needs to be set */
2660 spin_lock_irqsave(&dump_list_lock
, flags
);
2661 /* Don't allow registering multiple times */
2662 if (!dumper
->registered
) {
2663 dumper
->registered
= 1;
2664 list_add_tail_rcu(&dumper
->list
, &dump_list
);
2667 spin_unlock_irqrestore(&dump_list_lock
, flags
);
2671 EXPORT_SYMBOL_GPL(kmsg_dump_register
);
2674 * kmsg_dump_unregister - unregister a kmsg dumper.
2675 * @dumper: pointer to the kmsg_dumper structure
2677 * Removes a dump device from the system. Returns zero on success and
2678 * %-EINVAL otherwise.
2680 int kmsg_dump_unregister(struct kmsg_dumper
*dumper
)
2682 unsigned long flags
;
2685 spin_lock_irqsave(&dump_list_lock
, flags
);
2686 if (dumper
->registered
) {
2687 dumper
->registered
= 0;
2688 list_del_rcu(&dumper
->list
);
2691 spin_unlock_irqrestore(&dump_list_lock
, flags
);
2696 EXPORT_SYMBOL_GPL(kmsg_dump_unregister
);
2698 static bool always_kmsg_dump
;
2699 module_param_named(always_kmsg_dump
, always_kmsg_dump
, bool, S_IRUGO
| S_IWUSR
);
2702 * kmsg_dump - dump kernel log to kernel message dumpers.
2703 * @reason: the reason (oops, panic etc) for dumping
2705 * Call each of the registered dumper's dump() callback, which can
2706 * retrieve the kmsg records with kmsg_dump_get_line() or
2707 * kmsg_dump_get_buffer().
2709 void kmsg_dump(enum kmsg_dump_reason reason
)
2711 struct kmsg_dumper
*dumper
;
2712 unsigned long flags
;
2714 if ((reason
> KMSG_DUMP_OOPS
) && !always_kmsg_dump
)
2718 list_for_each_entry_rcu(dumper
, &dump_list
, list
) {
2719 if (dumper
->max_reason
&& reason
> dumper
->max_reason
)
2722 /* initialize iterator with data about the stored records */
2723 dumper
->active
= true;
2725 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2726 dumper
->cur_seq
= clear_seq
;
2727 dumper
->cur_idx
= clear_idx
;
2728 dumper
->next_seq
= log_next_seq
;
2729 dumper
->next_idx
= log_next_idx
;
2730 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2732 /* invoke dumper which will iterate over records */
2733 dumper
->dump(dumper
, reason
);
2735 /* reset iterator */
2736 dumper
->active
= false;
2742 * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
2743 * @dumper: registered kmsg dumper
2744 * @syslog: include the "<4>" prefixes
2745 * @line: buffer to copy the line to
2746 * @size: maximum size of the buffer
2747 * @len: length of line placed into buffer
2749 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2750 * record, and copy one record into the provided buffer.
2752 * Consecutive calls will return the next available record moving
2753 * towards the end of the buffer with the youngest messages.
2755 * A return value of FALSE indicates that there are no more records to
2758 * The function is similar to kmsg_dump_get_line(), but grabs no locks.
2760 bool kmsg_dump_get_line_nolock(struct kmsg_dumper
*dumper
, bool syslog
,
2761 char *line
, size_t size
, size_t *len
)
2763 struct printk_log
*msg
;
2767 if (!dumper
->active
)
2770 if (dumper
->cur_seq
< log_first_seq
) {
2771 /* messages are gone, move to first available one */
2772 dumper
->cur_seq
= log_first_seq
;
2773 dumper
->cur_idx
= log_first_idx
;
2777 if (dumper
->cur_seq
>= log_next_seq
)
2780 msg
= log_from_idx(dumper
->cur_idx
);
2781 l
= msg_print_text(msg
, 0, syslog
, line
, size
);
2783 dumper
->cur_idx
= log_next(dumper
->cur_idx
);
2793 * kmsg_dump_get_line - retrieve one kmsg log line
2794 * @dumper: registered kmsg dumper
2795 * @syslog: include the "<4>" prefixes
2796 * @line: buffer to copy the line to
2797 * @size: maximum size of the buffer
2798 * @len: length of line placed into buffer
2800 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2801 * record, and copy one record into the provided buffer.
2803 * Consecutive calls will return the next available record moving
2804 * towards the end of the buffer with the youngest messages.
2806 * A return value of FALSE indicates that there are no more records to
2809 bool kmsg_dump_get_line(struct kmsg_dumper
*dumper
, bool syslog
,
2810 char *line
, size_t size
, size_t *len
)
2812 unsigned long flags
;
2815 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2816 ret
= kmsg_dump_get_line_nolock(dumper
, syslog
, line
, size
, len
);
2817 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2821 EXPORT_SYMBOL_GPL(kmsg_dump_get_line
);
2824 * kmsg_dump_get_buffer - copy kmsg log lines
2825 * @dumper: registered kmsg dumper
2826 * @syslog: include the "<4>" prefixes
2827 * @buf: buffer to copy the line to
2828 * @size: maximum size of the buffer
2829 * @len: length of line placed into buffer
2831 * Start at the end of the kmsg buffer and fill the provided buffer
2832 * with as many of the the *youngest* kmsg records that fit into it.
2833 * If the buffer is large enough, all available kmsg records will be
2834 * copied with a single call.
2836 * Consecutive calls will fill the buffer with the next block of
2837 * available older records, not including the earlier retrieved ones.
2839 * A return value of FALSE indicates that there are no more records to
2842 bool kmsg_dump_get_buffer(struct kmsg_dumper
*dumper
, bool syslog
,
2843 char *buf
, size_t size
, size_t *len
)
2845 unsigned long flags
;
2850 enum log_flags prev
;
2854 if (!dumper
->active
)
2857 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2858 if (dumper
->cur_seq
< log_first_seq
) {
2859 /* messages are gone, move to first available one */
2860 dumper
->cur_seq
= log_first_seq
;
2861 dumper
->cur_idx
= log_first_idx
;
2865 if (dumper
->cur_seq
>= dumper
->next_seq
) {
2866 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2870 /* calculate length of entire buffer */
2871 seq
= dumper
->cur_seq
;
2872 idx
= dumper
->cur_idx
;
2874 while (seq
< dumper
->next_seq
) {
2875 struct printk_log
*msg
= log_from_idx(idx
);
2877 l
+= msg_print_text(msg
, prev
, true, NULL
, 0);
2878 idx
= log_next(idx
);
2883 /* move first record forward until length fits into the buffer */
2884 seq
= dumper
->cur_seq
;
2885 idx
= dumper
->cur_idx
;
2887 while (l
> size
&& seq
< dumper
->next_seq
) {
2888 struct printk_log
*msg
= log_from_idx(idx
);
2890 l
-= msg_print_text(msg
, prev
, true, NULL
, 0);
2891 idx
= log_next(idx
);
2896 /* last message in next interation */
2901 while (seq
< dumper
->next_seq
) {
2902 struct printk_log
*msg
= log_from_idx(idx
);
2904 l
+= msg_print_text(msg
, prev
, syslog
, buf
+ l
, size
- l
);
2905 idx
= log_next(idx
);
2910 dumper
->next_seq
= next_seq
;
2911 dumper
->next_idx
= next_idx
;
2913 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2919 EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer
);
2922 * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
2923 * @dumper: registered kmsg dumper
2925 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2926 * kmsg_dump_get_buffer() can be called again and used multiple
2927 * times within the same dumper.dump() callback.
2929 * The function is similar to kmsg_dump_rewind(), but grabs no locks.
2931 void kmsg_dump_rewind_nolock(struct kmsg_dumper
*dumper
)
2933 dumper
->cur_seq
= clear_seq
;
2934 dumper
->cur_idx
= clear_idx
;
2935 dumper
->next_seq
= log_next_seq
;
2936 dumper
->next_idx
= log_next_idx
;
2940 * kmsg_dump_rewind - reset the interator
2941 * @dumper: registered kmsg dumper
2943 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2944 * kmsg_dump_get_buffer() can be called again and used multiple
2945 * times within the same dumper.dump() callback.
2947 void kmsg_dump_rewind(struct kmsg_dumper
*dumper
)
2949 unsigned long flags
;
2951 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2952 kmsg_dump_rewind_nolock(dumper
);
2953 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2955 EXPORT_SYMBOL_GPL(kmsg_dump_rewind
);
2957 static char dump_stack_arch_desc_str
[128];
2960 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
2961 * @fmt: printf-style format string
2962 * @...: arguments for the format string
2964 * The configured string will be printed right after utsname during task
2965 * dumps. Usually used to add arch-specific system identifiers. If an
2966 * arch wants to make use of such an ID string, it should initialize this
2967 * as soon as possible during boot.
2969 void __init
dump_stack_set_arch_desc(const char *fmt
, ...)
2973 va_start(args
, fmt
);
2974 vsnprintf(dump_stack_arch_desc_str
, sizeof(dump_stack_arch_desc_str
),
2980 * dump_stack_print_info - print generic debug info for dump_stack()
2981 * @log_lvl: log level
2983 * Arch-specific dump_stack() implementations can use this function to
2984 * print out the same debug information as the generic dump_stack().
2986 void dump_stack_print_info(const char *log_lvl
)
2988 printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
2989 log_lvl
, raw_smp_processor_id(), current
->pid
, current
->comm
,
2990 print_tainted(), init_utsname()->release
,
2991 (int)strcspn(init_utsname()->version
, " "),
2992 init_utsname()->version
);
2994 if (dump_stack_arch_desc_str
[0] != '\0')
2995 printk("%sHardware name: %s\n",
2996 log_lvl
, dump_stack_arch_desc_str
);
2998 print_worker_info(log_lvl
, current
);
3002 * show_regs_print_info - print generic debug info for show_regs()
3003 * @log_lvl: log level
3005 * show_regs() implementations can use this function to print out generic
3006 * debug information.
3008 void show_regs_print_info(const char *log_lvl
)
3010 dump_stack_print_info(log_lvl
);
3012 printk("%stask: %p ti: %p task.ti: %p\n",
3013 log_lvl
, current
, current_thread_info(),
3014 task_thread_info(current
));