2 * linux/kernel/printk.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * Modified to make sys_syslog() more flexible: added commands to
7 * return the last 4k of kernel messages, regardless of whether
8 * they've been read or not. Added option to suppress kernel printk's
9 * to the console. Added hook for sending the console messages
10 * elsewhere, in preparation for a serial line console (someday).
12 * Modified for sysctl support, 1/8/97, Chris Horn.
13 * Fixed SMP synchronization, 08/08/99, Manfred Spraul
14 * manfred@colorfullife.com
15 * Rewrote bits to get rid of console_lock
16 * 01Mar01 Andrew Morton
19 #include <linux/kernel.h>
21 #include <linux/tty.h>
22 #include <linux/tty_driver.h>
23 #include <linux/console.h>
24 #include <linux/init.h>
25 #include <linux/jiffies.h>
26 #include <linux/nmi.h>
27 #include <linux/module.h>
28 #include <linux/moduleparam.h>
29 #include <linux/interrupt.h> /* For in_interrupt() */
30 #include <linux/delay.h>
31 #include <linux/smp.h>
32 #include <linux/security.h>
33 #include <linux/bootmem.h>
34 #include <linux/memblock.h>
35 #include <linux/aio.h>
36 #include <linux/syscalls.h>
37 #include <linux/kexec.h>
38 #include <linux/kdb.h>
39 #include <linux/ratelimit.h>
40 #include <linux/kmsg_dump.h>
41 #include <linux/syslog.h>
42 #include <linux/cpu.h>
43 #include <linux/notifier.h>
44 #include <linux/rculist.h>
45 #include <linux/poll.h>
46 #include <linux/irq_work.h>
47 #include <linux/utsname.h>
49 #include <asm/uaccess.h>
51 #define CREATE_TRACE_POINTS
52 #include <trace/events/printk.h>
54 #include "console_cmdline.h"
57 /* printk's without a loglevel use this.. */
58 #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
60 /* We show everything that is MORE important than this.. */
61 #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
62 #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
64 int console_printk
[4] = {
65 DEFAULT_CONSOLE_LOGLEVEL
, /* console_loglevel */
66 DEFAULT_MESSAGE_LOGLEVEL
, /* default_message_loglevel */
67 MINIMUM_CONSOLE_LOGLEVEL
, /* minimum_console_loglevel */
68 DEFAULT_CONSOLE_LOGLEVEL
, /* default_console_loglevel */
72 * Low level drivers may need that to know if they can schedule in
73 * their unblank() callback or not. So let's export it.
76 EXPORT_SYMBOL(oops_in_progress
);
79 * console_sem protects the console_drivers list, and also
80 * provides serialisation for access to the entire console
83 static DEFINE_SEMAPHORE(console_sem
);
84 struct console
*console_drivers
;
85 EXPORT_SYMBOL_GPL(console_drivers
);
88 static struct lockdep_map console_lock_dep_map
= {
89 .name
= "console_lock"
94 * This is used for debugging the mess that is the VT code by
95 * keeping track if we have the console semaphore held. It's
96 * definitely not the perfect debug tool (we don't know if _WE_
97 * hold it are racing, but it helps tracking those weird code
98 * path in the console code where we end up in places I want
99 * locked without the console sempahore held
101 static int console_locked
, console_suspended
;
104 * If exclusive_console is non-NULL then only this console is to be printed to.
106 static struct console
*exclusive_console
;
109 * Array of consoles built from command line options (console=)
112 #define MAX_CMDLINECONSOLES 8
114 static struct console_cmdline console_cmdline
[MAX_CMDLINECONSOLES
];
116 static int selected_console
= -1;
117 static int preferred_console
= -1;
118 int console_set_on_cmdline
;
119 EXPORT_SYMBOL(console_set_on_cmdline
);
121 /* Flag: console code may call schedule() */
122 static int console_may_schedule
;
125 * The printk log buffer consists of a chain of concatenated variable
126 * length records. Every record starts with a record header, containing
127 * the overall length of the record.
129 * The heads to the first and last entry in the buffer, as well as the
130 * sequence numbers of these both entries are maintained when messages
133 * If the heads indicate available messages, the length in the header
134 * tells the start next message. A length == 0 for the next message
135 * indicates a wrap-around to the beginning of the buffer.
137 * Every record carries the monotonic timestamp in microseconds, as well as
138 * the standard userspace syslog level and syslog facility. The usual
139 * kernel messages use LOG_KERN; userspace-injected messages always carry
140 * a matching syslog facility, by default LOG_USER. The origin of every
141 * message can be reliably determined that way.
143 * The human readable log message directly follows the message header. The
144 * length of the message text is stored in the header, the stored message
147 * Optionally, a message can carry a dictionary of properties (key/value pairs),
148 * to provide userspace with a machine-readable message context.
150 * Examples for well-defined, commonly used property names are:
151 * DEVICE=b12:8 device identifier
155 * +sound:card0 subsystem:devname
156 * SUBSYSTEM=pci driver-core subsystem name
158 * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
159 * follows directly after a '=' character. Every property is terminated by
160 * a '\0' character. The last property is not terminated.
162 * Example of a message structure:
163 * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec
164 * 0008 34 00 record is 52 bytes long
165 * 000a 0b 00 text is 11 bytes long
166 * 000c 1f 00 dictionary is 23 bytes long
167 * 000e 03 00 LOG_KERN (facility) LOG_ERR (level)
168 * 0010 69 74 27 73 20 61 20 6c "it's a l"
170 * 001b 44 45 56 49 43 "DEVIC"
171 * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D"
172 * 52 49 56 45 52 3d 62 75 "RIVER=bu"
174 * 0032 00 00 00 padding to next message header
176 * The 'struct log' buffer header must never be directly exported to
177 * userspace, it is a kernel-private implementation detail that might
178 * need to be changed in the future, when the requirements change.
180 * /dev/kmsg exports the structured data in the following line format:
181 * "level,sequnum,timestamp;<message text>\n"
183 * The optional key/value pairs are attached as continuation lines starting
184 * with a space character and terminated by a newline. All possible
185 * non-prinatable characters are escaped in the "\xff" notation.
187 * Users of the export format should ignore possible additional values
188 * separated by ',', and find the message after the ';' character.
192 LOG_NOCONS
= 1, /* already flushed, do not print to console */
193 LOG_NEWLINE
= 2, /* text ended with a newline */
194 LOG_PREFIX
= 4, /* text started with a prefix */
195 LOG_CONT
= 8, /* text is a fragment of a continuation line */
199 u64 ts_nsec
; /* timestamp in nanoseconds */
200 u16 len
; /* length of entire record */
201 u16 text_len
; /* length of text buffer */
202 u16 dict_len
; /* length of dictionary buffer */
203 u8 facility
; /* syslog facility */
204 u8 flags
:5; /* internal record flags */
205 u8 level
:3; /* syslog level */
209 * The logbuf_lock protects kmsg buffer, indices, counters. It is also
210 * used in interesting ways to provide interlocking in console_unlock();
212 static DEFINE_RAW_SPINLOCK(logbuf_lock
);
215 DECLARE_WAIT_QUEUE_HEAD(log_wait
);
216 /* the next printk record to read by syslog(READ) or /proc/kmsg */
217 static u64 syslog_seq
;
218 static u32 syslog_idx
;
219 static enum log_flags syslog_prev
;
220 static size_t syslog_partial
;
222 /* index and sequence number of the first record stored in the buffer */
223 static u64 log_first_seq
;
224 static u32 log_first_idx
;
226 /* index and sequence number of the next record to store in the buffer */
227 static u64 log_next_seq
;
228 static u32 log_next_idx
;
230 /* the next printk record to write to the console */
231 static u64 console_seq
;
232 static u32 console_idx
;
233 static enum log_flags console_prev
;
235 /* the next printk record to read after the last 'clear' command */
236 static u64 clear_seq
;
237 static u32 clear_idx
;
239 #define PREFIX_MAX 32
240 #define LOG_LINE_MAX 1024 - PREFIX_MAX
243 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
246 #define LOG_ALIGN __alignof__(struct log)
248 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
249 static char __log_buf
[__LOG_BUF_LEN
] __aligned(LOG_ALIGN
);
250 static char *log_buf
= __log_buf
;
251 static u32 log_buf_len
= __LOG_BUF_LEN
;
253 /* cpu currently holding logbuf_lock */
254 static volatile unsigned int logbuf_cpu
= UINT_MAX
;
256 /* human readable text of the record */
257 static char *log_text(const struct log
*msg
)
259 return (char *)msg
+ sizeof(struct log
);
262 /* optional key/value pair dictionary attached to the record */
263 static char *log_dict(const struct log
*msg
)
265 return (char *)msg
+ sizeof(struct log
) + msg
->text_len
;
268 /* get record by index; idx must point to valid msg */
269 static struct log
*log_from_idx(u32 idx
)
271 struct log
*msg
= (struct log
*)(log_buf
+ idx
);
274 * A length == 0 record is the end of buffer marker. Wrap around and
275 * read the message at the start of the buffer.
278 return (struct log
*)log_buf
;
282 /* get next record; idx must point to valid msg */
283 static u32
log_next(u32 idx
)
285 struct log
*msg
= (struct log
*)(log_buf
+ idx
);
287 /* length == 0 indicates the end of the buffer; wrap */
289 * A length == 0 record is the end of buffer marker. Wrap around and
290 * read the message at the start of the buffer as *this* one, and
291 * return the one after that.
294 msg
= (struct log
*)log_buf
;
297 return idx
+ msg
->len
;
300 /* insert record into the buffer, discard old ones, update heads */
301 static void log_store(int facility
, int level
,
302 enum log_flags flags
, u64 ts_nsec
,
303 const char *dict
, u16 dict_len
,
304 const char *text
, u16 text_len
)
309 /* number of '\0' padding bytes to next message */
310 size
= sizeof(struct log
) + text_len
+ dict_len
;
311 pad_len
= (-size
) & (LOG_ALIGN
- 1);
314 while (log_first_seq
< log_next_seq
) {
317 if (log_next_idx
> log_first_idx
)
318 free
= max(log_buf_len
- log_next_idx
, log_first_idx
);
320 free
= log_first_idx
- log_next_idx
;
322 if (free
> size
+ sizeof(struct log
))
325 /* drop old messages until we have enough contiuous space */
326 log_first_idx
= log_next(log_first_idx
);
330 if (log_next_idx
+ size
+ sizeof(struct log
) >= log_buf_len
) {
332 * This message + an additional empty header does not fit
333 * at the end of the buffer. Add an empty header with len == 0
334 * to signify a wrap around.
336 memset(log_buf
+ log_next_idx
, 0, sizeof(struct log
));
341 msg
= (struct log
*)(log_buf
+ log_next_idx
);
342 memcpy(log_text(msg
), text
, text_len
);
343 msg
->text_len
= text_len
;
344 memcpy(log_dict(msg
), dict
, dict_len
);
345 msg
->dict_len
= dict_len
;
346 msg
->facility
= facility
;
347 msg
->level
= level
& 7;
348 msg
->flags
= flags
& 0x1f;
350 msg
->ts_nsec
= ts_nsec
;
352 msg
->ts_nsec
= local_clock();
353 memset(log_dict(msg
) + dict_len
, 0, pad_len
);
354 msg
->len
= sizeof(struct log
) + text_len
+ dict_len
+ pad_len
;
357 log_next_idx
+= msg
->len
;
361 #ifdef CONFIG_SECURITY_DMESG_RESTRICT
362 int dmesg_restrict
= 1;
367 static int syslog_action_restricted(int type
)
372 * Unless restricted, we allow "read all" and "get buffer size"
375 return type
!= SYSLOG_ACTION_READ_ALL
&&
376 type
!= SYSLOG_ACTION_SIZE_BUFFER
;
379 static int check_syslog_permissions(int type
, bool from_file
)
382 * If this is from /proc/kmsg and we've already opened it, then we've
383 * already done the capabilities checks at open time.
385 if (from_file
&& type
!= SYSLOG_ACTION_OPEN
)
388 if (syslog_action_restricted(type
)) {
389 if (capable(CAP_SYSLOG
))
392 * For historical reasons, accept CAP_SYS_ADMIN too, with
395 if (capable(CAP_SYS_ADMIN
)) {
396 pr_warn_once("%s (%d): Attempt to access syslog with "
397 "CAP_SYS_ADMIN but no CAP_SYSLOG "
399 current
->comm
, task_pid_nr(current
));
404 return security_syslog(type
);
408 /* /dev/kmsg - userspace message inject/listen interface */
409 struct devkmsg_user
{
417 static ssize_t
devkmsg_writev(struct kiocb
*iocb
, const struct iovec
*iv
,
418 unsigned long count
, loff_t pos
)
422 int level
= default_message_loglevel
;
423 int facility
= 1; /* LOG_USER */
424 size_t len
= iov_length(iv
, count
);
427 if (len
> LOG_LINE_MAX
)
429 buf
= kmalloc(len
+1, GFP_KERNEL
);
434 for (i
= 0; i
< count
; i
++) {
435 if (copy_from_user(line
, iv
[i
].iov_base
, iv
[i
].iov_len
)) {
439 line
+= iv
[i
].iov_len
;
443 * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
444 * the decimal value represents 32bit, the lower 3 bit are the log
445 * level, the rest are the log facility.
447 * If no prefix or no userspace facility is specified, we
448 * enforce LOG_USER, to be able to reliably distinguish
449 * kernel-generated messages from userspace-injected ones.
452 if (line
[0] == '<') {
455 i
= simple_strtoul(line
+1, &endp
, 10);
456 if (endp
&& endp
[0] == '>') {
467 printk_emit(facility
, level
, NULL
, 0, "%s", line
);
473 static ssize_t
devkmsg_read(struct file
*file
, char __user
*buf
,
474 size_t count
, loff_t
*ppos
)
476 struct devkmsg_user
*user
= file
->private_data
;
487 ret
= mutex_lock_interruptible(&user
->lock
);
490 raw_spin_lock_irq(&logbuf_lock
);
491 while (user
->seq
== log_next_seq
) {
492 if (file
->f_flags
& O_NONBLOCK
) {
494 raw_spin_unlock_irq(&logbuf_lock
);
498 raw_spin_unlock_irq(&logbuf_lock
);
499 ret
= wait_event_interruptible(log_wait
,
500 user
->seq
!= log_next_seq
);
503 raw_spin_lock_irq(&logbuf_lock
);
506 if (user
->seq
< log_first_seq
) {
507 /* our last seen message is gone, return error and reset */
508 user
->idx
= log_first_idx
;
509 user
->seq
= log_first_seq
;
511 raw_spin_unlock_irq(&logbuf_lock
);
515 msg
= log_from_idx(user
->idx
);
516 ts_usec
= msg
->ts_nsec
;
517 do_div(ts_usec
, 1000);
520 * If we couldn't merge continuation line fragments during the print,
521 * export the stored flags to allow an optional external merge of the
522 * records. Merging the records isn't always neccessarily correct, like
523 * when we hit a race during printing. In most cases though, it produces
524 * better readable output. 'c' in the record flags mark the first
525 * fragment of a line, '+' the following.
527 if (msg
->flags
& LOG_CONT
&& !(user
->prev
& LOG_CONT
))
529 else if ((msg
->flags
& LOG_CONT
) ||
530 ((user
->prev
& LOG_CONT
) && !(msg
->flags
& LOG_PREFIX
)))
533 len
= sprintf(user
->buf
, "%u,%llu,%llu,%c;",
534 (msg
->facility
<< 3) | msg
->level
,
535 user
->seq
, ts_usec
, cont
);
536 user
->prev
= msg
->flags
;
538 /* escape non-printable characters */
539 for (i
= 0; i
< msg
->text_len
; i
++) {
540 unsigned char c
= log_text(msg
)[i
];
542 if (c
< ' ' || c
>= 127 || c
== '\\')
543 len
+= sprintf(user
->buf
+ len
, "\\x%02x", c
);
545 user
->buf
[len
++] = c
;
547 user
->buf
[len
++] = '\n';
552 for (i
= 0; i
< msg
->dict_len
; i
++) {
553 unsigned char c
= log_dict(msg
)[i
];
556 user
->buf
[len
++] = ' ';
561 user
->buf
[len
++] = '\n';
566 if (c
< ' ' || c
>= 127 || c
== '\\') {
567 len
+= sprintf(user
->buf
+ len
, "\\x%02x", c
);
571 user
->buf
[len
++] = c
;
573 user
->buf
[len
++] = '\n';
576 user
->idx
= log_next(user
->idx
);
578 raw_spin_unlock_irq(&logbuf_lock
);
585 if (copy_to_user(buf
, user
->buf
, len
)) {
591 mutex_unlock(&user
->lock
);
595 static loff_t
devkmsg_llseek(struct file
*file
, loff_t offset
, int whence
)
597 struct devkmsg_user
*user
= file
->private_data
;
605 raw_spin_lock_irq(&logbuf_lock
);
608 /* the first record */
609 user
->idx
= log_first_idx
;
610 user
->seq
= log_first_seq
;
614 * The first record after the last SYSLOG_ACTION_CLEAR,
615 * like issued by 'dmesg -c'. Reading /dev/kmsg itself
616 * changes no global state, and does not clear anything.
618 user
->idx
= clear_idx
;
619 user
->seq
= clear_seq
;
622 /* after the last record */
623 user
->idx
= log_next_idx
;
624 user
->seq
= log_next_seq
;
629 raw_spin_unlock_irq(&logbuf_lock
);
633 static unsigned int devkmsg_poll(struct file
*file
, poll_table
*wait
)
635 struct devkmsg_user
*user
= file
->private_data
;
639 return POLLERR
|POLLNVAL
;
641 poll_wait(file
, &log_wait
, wait
);
643 raw_spin_lock_irq(&logbuf_lock
);
644 if (user
->seq
< log_next_seq
) {
645 /* return error when data has vanished underneath us */
646 if (user
->seq
< log_first_seq
)
647 ret
= POLLIN
|POLLRDNORM
|POLLERR
|POLLPRI
;
649 ret
= POLLIN
|POLLRDNORM
;
651 raw_spin_unlock_irq(&logbuf_lock
);
656 static int devkmsg_open(struct inode
*inode
, struct file
*file
)
658 struct devkmsg_user
*user
;
661 /* write-only does not need any file context */
662 if ((file
->f_flags
& O_ACCMODE
) == O_WRONLY
)
665 err
= check_syslog_permissions(SYSLOG_ACTION_READ_ALL
,
670 user
= kmalloc(sizeof(struct devkmsg_user
), GFP_KERNEL
);
674 mutex_init(&user
->lock
);
676 raw_spin_lock_irq(&logbuf_lock
);
677 user
->idx
= log_first_idx
;
678 user
->seq
= log_first_seq
;
679 raw_spin_unlock_irq(&logbuf_lock
);
681 file
->private_data
= user
;
685 static int devkmsg_release(struct inode
*inode
, struct file
*file
)
687 struct devkmsg_user
*user
= file
->private_data
;
692 mutex_destroy(&user
->lock
);
697 const struct file_operations kmsg_fops
= {
698 .open
= devkmsg_open
,
699 .read
= devkmsg_read
,
700 .aio_write
= devkmsg_writev
,
701 .llseek
= devkmsg_llseek
,
702 .poll
= devkmsg_poll
,
703 .release
= devkmsg_release
,
708 * This appends the listed symbols to /proc/vmcoreinfo
710 * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
711 * obtain access to symbols that are otherwise very difficult to locate. These
712 * symbols are specifically used so that utilities can access and extract the
713 * dmesg log from a vmcore file after a crash.
715 void log_buf_kexec_setup(void)
717 VMCOREINFO_SYMBOL(log_buf
);
718 VMCOREINFO_SYMBOL(log_buf_len
);
719 VMCOREINFO_SYMBOL(log_first_idx
);
720 VMCOREINFO_SYMBOL(log_next_idx
);
722 * Export struct log size and field offsets. User space tools can
723 * parse it and detect any changes to structure down the line.
725 VMCOREINFO_STRUCT_SIZE(log
);
726 VMCOREINFO_OFFSET(log
, ts_nsec
);
727 VMCOREINFO_OFFSET(log
, len
);
728 VMCOREINFO_OFFSET(log
, text_len
);
729 VMCOREINFO_OFFSET(log
, dict_len
);
733 /* requested log_buf_len from kernel cmdline */
734 static unsigned long __initdata new_log_buf_len
;
736 /* save requested log_buf_len since it's too early to process it */
737 static int __init
log_buf_len_setup(char *str
)
739 unsigned size
= memparse(str
, &str
);
742 size
= roundup_pow_of_two(size
);
743 if (size
> log_buf_len
)
744 new_log_buf_len
= size
;
748 early_param("log_buf_len", log_buf_len_setup
);
750 void __init
setup_log_buf(int early
)
756 if (!new_log_buf_len
)
762 mem
= memblock_alloc(new_log_buf_len
, PAGE_SIZE
);
765 new_log_buf
= __va(mem
);
767 new_log_buf
= alloc_bootmem_nopanic(new_log_buf_len
);
770 if (unlikely(!new_log_buf
)) {
771 pr_err("log_buf_len: %ld bytes not available\n",
776 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
777 log_buf_len
= new_log_buf_len
;
778 log_buf
= new_log_buf
;
780 free
= __LOG_BUF_LEN
- log_next_idx
;
781 memcpy(log_buf
, __log_buf
, __LOG_BUF_LEN
);
782 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
784 pr_info("log_buf_len: %d\n", log_buf_len
);
785 pr_info("early log buf free: %d(%d%%)\n",
786 free
, (free
* 100) / __LOG_BUF_LEN
);
789 static bool __read_mostly ignore_loglevel
;
791 static int __init
ignore_loglevel_setup(char *str
)
794 printk(KERN_INFO
"debug: ignoring loglevel setting.\n");
799 early_param("ignore_loglevel", ignore_loglevel_setup
);
800 module_param(ignore_loglevel
, bool, S_IRUGO
| S_IWUSR
);
801 MODULE_PARM_DESC(ignore_loglevel
, "ignore loglevel setting, to"
802 "print all kernel messages to the console.");
804 #ifdef CONFIG_BOOT_PRINTK_DELAY
806 static int boot_delay
; /* msecs delay after each printk during bootup */
807 static unsigned long long loops_per_msec
; /* based on boot_delay */
809 static int __init
boot_delay_setup(char *str
)
813 lpj
= preset_lpj
? preset_lpj
: 1000000; /* some guess */
814 loops_per_msec
= (unsigned long long)lpj
/ 1000 * HZ
;
816 get_option(&str
, &boot_delay
);
817 if (boot_delay
> 10 * 1000)
820 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
821 "HZ: %d, loops_per_msec: %llu\n",
822 boot_delay
, preset_lpj
, lpj
, HZ
, loops_per_msec
);
825 __setup("boot_delay=", boot_delay_setup
);
827 static void boot_delay_msec(int level
)
829 unsigned long long k
;
830 unsigned long timeout
;
832 if ((boot_delay
== 0 || system_state
!= SYSTEM_BOOTING
)
833 || (level
>= console_loglevel
&& !ignore_loglevel
)) {
837 k
= (unsigned long long)loops_per_msec
* boot_delay
;
839 timeout
= jiffies
+ msecs_to_jiffies(boot_delay
);
844 * use (volatile) jiffies to prevent
845 * compiler reduction; loop termination via jiffies
846 * is secondary and may or may not happen.
848 if (time_after(jiffies
, timeout
))
850 touch_nmi_watchdog();
854 static inline void boot_delay_msec(int level
)
859 #if defined(CONFIG_PRINTK_TIME)
860 static bool printk_time
= 1;
862 static bool printk_time
;
864 module_param_named(time
, printk_time
, bool, S_IRUGO
| S_IWUSR
);
866 static size_t print_time(u64 ts
, char *buf
)
868 unsigned long rem_nsec
;
873 rem_nsec
= do_div(ts
, 1000000000);
876 return snprintf(NULL
, 0, "[%5lu.000000] ", (unsigned long)ts
);
878 return sprintf(buf
, "[%5lu.%06lu] ",
879 (unsigned long)ts
, rem_nsec
/ 1000);
882 static size_t print_prefix(const struct log
*msg
, bool syslog
, char *buf
)
885 unsigned int prefix
= (msg
->facility
<< 3) | msg
->level
;
889 len
+= sprintf(buf
, "<%u>", prefix
);
894 else if (prefix
> 99)
901 len
+= print_time(msg
->ts_nsec
, buf
? buf
+ len
: NULL
);
905 static size_t msg_print_text(const struct log
*msg
, enum log_flags prev
,
906 bool syslog
, char *buf
, size_t size
)
908 const char *text
= log_text(msg
);
909 size_t text_size
= msg
->text_len
;
914 if ((prev
& LOG_CONT
) && !(msg
->flags
& LOG_PREFIX
))
917 if (msg
->flags
& LOG_CONT
) {
918 if ((prev
& LOG_CONT
) && !(prev
& LOG_NEWLINE
))
921 if (!(msg
->flags
& LOG_NEWLINE
))
926 const char *next
= memchr(text
, '\n', text_size
);
930 text_len
= next
- text
;
932 text_size
-= next
- text
;
934 text_len
= text_size
;
938 if (print_prefix(msg
, syslog
, NULL
) +
939 text_len
+ 1 >= size
- len
)
943 len
+= print_prefix(msg
, syslog
, buf
+ len
);
944 memcpy(buf
+ len
, text
, text_len
);
949 /* SYSLOG_ACTION_* buffer size only calculation */
951 len
+= print_prefix(msg
, syslog
, NULL
);
964 static int syslog_print(char __user
*buf
, int size
)
970 text
= kmalloc(LOG_LINE_MAX
+ PREFIX_MAX
, GFP_KERNEL
);
978 raw_spin_lock_irq(&logbuf_lock
);
979 if (syslog_seq
< log_first_seq
) {
980 /* messages are gone, move to first one */
981 syslog_seq
= log_first_seq
;
982 syslog_idx
= log_first_idx
;
986 if (syslog_seq
== log_next_seq
) {
987 raw_spin_unlock_irq(&logbuf_lock
);
991 skip
= syslog_partial
;
992 msg
= log_from_idx(syslog_idx
);
993 n
= msg_print_text(msg
, syslog_prev
, true, text
,
994 LOG_LINE_MAX
+ PREFIX_MAX
);
995 if (n
- syslog_partial
<= size
) {
996 /* message fits into buffer, move forward */
997 syslog_idx
= log_next(syslog_idx
);
999 syslog_prev
= msg
->flags
;
1000 n
-= syslog_partial
;
1003 /* partial read(), remember position */
1005 syslog_partial
+= n
;
1008 raw_spin_unlock_irq(&logbuf_lock
);
1013 if (copy_to_user(buf
, text
+ skip
, n
)) {
1028 static int syslog_print_all(char __user
*buf
, int size
, bool clear
)
1033 text
= kmalloc(LOG_LINE_MAX
+ PREFIX_MAX
, GFP_KERNEL
);
1037 raw_spin_lock_irq(&logbuf_lock
);
1042 enum log_flags prev
;
1044 if (clear_seq
< log_first_seq
) {
1045 /* messages are gone, move to first available one */
1046 clear_seq
= log_first_seq
;
1047 clear_idx
= log_first_idx
;
1051 * Find first record that fits, including all following records,
1052 * into the user-provided buffer for this dump.
1057 while (seq
< log_next_seq
) {
1058 struct log
*msg
= log_from_idx(idx
);
1060 len
+= msg_print_text(msg
, prev
, true, NULL
, 0);
1062 idx
= log_next(idx
);
1066 /* move first record forward until length fits into the buffer */
1070 while (len
> size
&& seq
< log_next_seq
) {
1071 struct log
*msg
= log_from_idx(idx
);
1073 len
-= msg_print_text(msg
, prev
, true, NULL
, 0);
1075 idx
= log_next(idx
);
1079 /* last message fitting into this dump */
1080 next_seq
= log_next_seq
;
1084 while (len
>= 0 && seq
< next_seq
) {
1085 struct log
*msg
= log_from_idx(idx
);
1088 textlen
= msg_print_text(msg
, prev
, true, text
,
1089 LOG_LINE_MAX
+ PREFIX_MAX
);
1094 idx
= log_next(idx
);
1098 raw_spin_unlock_irq(&logbuf_lock
);
1099 if (copy_to_user(buf
+ len
, text
, textlen
))
1103 raw_spin_lock_irq(&logbuf_lock
);
1105 if (seq
< log_first_seq
) {
1106 /* messages are gone, move to next one */
1107 seq
= log_first_seq
;
1108 idx
= log_first_idx
;
1115 clear_seq
= log_next_seq
;
1116 clear_idx
= log_next_idx
;
1118 raw_spin_unlock_irq(&logbuf_lock
);
1124 int do_syslog(int type
, char __user
*buf
, int len
, bool from_file
)
1127 static int saved_console_loglevel
= -1;
1130 error
= check_syslog_permissions(type
, from_file
);
1134 error
= security_syslog(type
);
1139 case SYSLOG_ACTION_CLOSE
: /* Close log */
1141 case SYSLOG_ACTION_OPEN
: /* Open log */
1143 case SYSLOG_ACTION_READ
: /* Read from log */
1145 if (!buf
|| len
< 0)
1150 if (!access_ok(VERIFY_WRITE
, buf
, len
)) {
1154 error
= wait_event_interruptible(log_wait
,
1155 syslog_seq
!= log_next_seq
);
1158 error
= syslog_print(buf
, len
);
1160 /* Read/clear last kernel messages */
1161 case SYSLOG_ACTION_READ_CLEAR
:
1164 /* Read last kernel messages */
1165 case SYSLOG_ACTION_READ_ALL
:
1167 if (!buf
|| len
< 0)
1172 if (!access_ok(VERIFY_WRITE
, buf
, len
)) {
1176 error
= syslog_print_all(buf
, len
, clear
);
1178 /* Clear ring buffer */
1179 case SYSLOG_ACTION_CLEAR
:
1180 syslog_print_all(NULL
, 0, true);
1182 /* Disable logging to console */
1183 case SYSLOG_ACTION_CONSOLE_OFF
:
1184 if (saved_console_loglevel
== -1)
1185 saved_console_loglevel
= console_loglevel
;
1186 console_loglevel
= minimum_console_loglevel
;
1188 /* Enable logging to console */
1189 case SYSLOG_ACTION_CONSOLE_ON
:
1190 if (saved_console_loglevel
!= -1) {
1191 console_loglevel
= saved_console_loglevel
;
1192 saved_console_loglevel
= -1;
1195 /* Set level of messages printed to console */
1196 case SYSLOG_ACTION_CONSOLE_LEVEL
:
1198 if (len
< 1 || len
> 8)
1200 if (len
< minimum_console_loglevel
)
1201 len
= minimum_console_loglevel
;
1202 console_loglevel
= len
;
1203 /* Implicitly re-enable logging to console */
1204 saved_console_loglevel
= -1;
1207 /* Number of chars in the log buffer */
1208 case SYSLOG_ACTION_SIZE_UNREAD
:
1209 raw_spin_lock_irq(&logbuf_lock
);
1210 if (syslog_seq
< log_first_seq
) {
1211 /* messages are gone, move to first one */
1212 syslog_seq
= log_first_seq
;
1213 syslog_idx
= log_first_idx
;
1219 * Short-cut for poll(/"proc/kmsg") which simply checks
1220 * for pending data, not the size; return the count of
1221 * records, not the length.
1223 error
= log_next_idx
- syslog_idx
;
1225 u64 seq
= syslog_seq
;
1226 u32 idx
= syslog_idx
;
1227 enum log_flags prev
= syslog_prev
;
1230 while (seq
< log_next_seq
) {
1231 struct log
*msg
= log_from_idx(idx
);
1233 error
+= msg_print_text(msg
, prev
, true, NULL
, 0);
1234 idx
= log_next(idx
);
1238 error
-= syslog_partial
;
1240 raw_spin_unlock_irq(&logbuf_lock
);
1242 /* Size of the log buffer */
1243 case SYSLOG_ACTION_SIZE_BUFFER
:
1244 error
= log_buf_len
;
1254 SYSCALL_DEFINE3(syslog
, int, type
, char __user
*, buf
, int, len
)
1256 return do_syslog(type
, buf
, len
, SYSLOG_FROM_READER
);
1260 * Call the console drivers, asking them to write out
1261 * log_buf[start] to log_buf[end - 1].
1262 * The console_lock must be held.
1264 static void call_console_drivers(int level
, const char *text
, size_t len
)
1266 struct console
*con
;
1268 trace_console(text
, len
);
1270 if (level
>= console_loglevel
&& !ignore_loglevel
)
1272 if (!console_drivers
)
1275 for_each_console(con
) {
1276 if (exclusive_console
&& con
!= exclusive_console
)
1278 if (!(con
->flags
& CON_ENABLED
))
1282 if (!cpu_online(smp_processor_id()) &&
1283 !(con
->flags
& CON_ANYTIME
))
1285 con
->write(con
, text
, len
);
1290 * Zap console related locks when oopsing. Only zap at most once
1291 * every 10 seconds, to leave time for slow consoles to print a
1294 static void zap_locks(void)
1296 static unsigned long oops_timestamp
;
1298 if (time_after_eq(jiffies
, oops_timestamp
) &&
1299 !time_after(jiffies
, oops_timestamp
+ 30 * HZ
))
1302 oops_timestamp
= jiffies
;
1305 /* If a crash is occurring, make sure we can't deadlock */
1306 raw_spin_lock_init(&logbuf_lock
);
1307 /* And make sure that we print immediately */
1308 sema_init(&console_sem
, 1);
1311 /* Check if we have any console registered that can be called early in boot. */
1312 static int have_callable_console(void)
1314 struct console
*con
;
1316 for_each_console(con
)
1317 if (con
->flags
& CON_ANYTIME
)
1324 * Can we actually use the console at this time on this cpu?
1326 * Console drivers may assume that per-cpu resources have
1327 * been allocated. So unless they're explicitly marked as
1328 * being able to cope (CON_ANYTIME) don't call them until
1329 * this CPU is officially up.
1331 static inline int can_use_console(unsigned int cpu
)
1333 return cpu_online(cpu
) || have_callable_console();
1337 * Try to get console ownership to actually show the kernel
1338 * messages from a 'printk'. Return true (and with the
1339 * console_lock held, and 'console_locked' set) if it
1340 * is successful, false otherwise.
1342 * This gets called with the 'logbuf_lock' spinlock held and
1343 * interrupts disabled. It should return with 'lockbuf_lock'
1344 * released but interrupts still disabled.
1346 static int console_trylock_for_printk(unsigned int cpu
)
1347 __releases(&logbuf_lock
)
1349 int retval
= 0, wake
= 0;
1351 if (console_trylock()) {
1355 * If we can't use the console, we need to release
1356 * the console semaphore by hand to avoid flushing
1357 * the buffer. We need to hold the console semaphore
1358 * in order to do this test safely.
1360 if (!can_use_console(cpu
)) {
1366 logbuf_cpu
= UINT_MAX
;
1367 raw_spin_unlock(&logbuf_lock
);
1373 int printk_delay_msec __read_mostly
;
1375 static inline void printk_delay(void)
1377 if (unlikely(printk_delay_msec
)) {
1378 int m
= printk_delay_msec
;
1382 touch_nmi_watchdog();
1388 * Continuation lines are buffered, and not committed to the record buffer
1389 * until the line is complete, or a race forces it. The line fragments
1390 * though, are printed immediately to the consoles to ensure everything has
1391 * reached the console in case of a kernel crash.
1393 static struct cont
{
1394 char buf
[LOG_LINE_MAX
];
1395 size_t len
; /* length == 0 means unused buffer */
1396 size_t cons
; /* bytes written to console */
1397 struct task_struct
*owner
; /* task of first print*/
1398 u64 ts_nsec
; /* time of first print */
1399 u8 level
; /* log level of first message */
1400 u8 facility
; /* log level of first message */
1401 enum log_flags flags
; /* prefix, newline flags */
1402 bool flushed
:1; /* buffer sealed and committed */
1405 static void cont_flush(enum log_flags flags
)
1414 * If a fragment of this line was directly flushed to the
1415 * console; wait for the console to pick up the rest of the
1416 * line. LOG_NOCONS suppresses a duplicated output.
1418 log_store(cont
.facility
, cont
.level
, flags
| LOG_NOCONS
,
1419 cont
.ts_nsec
, NULL
, 0, cont
.buf
, cont
.len
);
1421 cont
.flushed
= true;
1424 * If no fragment of this line ever reached the console,
1425 * just submit it to the store and free the buffer.
1427 log_store(cont
.facility
, cont
.level
, flags
, 0,
1428 NULL
, 0, cont
.buf
, cont
.len
);
1433 static bool cont_add(int facility
, int level
, const char *text
, size_t len
)
1435 if (cont
.len
&& cont
.flushed
)
1438 if (cont
.len
+ len
> sizeof(cont
.buf
)) {
1439 /* the line gets too long, split it up in separate records */
1440 cont_flush(LOG_CONT
);
1445 cont
.facility
= facility
;
1447 cont
.owner
= current
;
1448 cont
.ts_nsec
= local_clock();
1451 cont
.flushed
= false;
1454 memcpy(cont
.buf
+ cont
.len
, text
, len
);
1457 if (cont
.len
> (sizeof(cont
.buf
) * 80) / 100)
1458 cont_flush(LOG_CONT
);
1463 static size_t cont_print_text(char *text
, size_t size
)
1468 if (cont
.cons
== 0 && (console_prev
& LOG_NEWLINE
)) {
1469 textlen
+= print_time(cont
.ts_nsec
, text
);
1473 len
= cont
.len
- cont
.cons
;
1477 memcpy(text
+ textlen
, cont
.buf
+ cont
.cons
, len
);
1479 cont
.cons
= cont
.len
;
1483 if (cont
.flags
& LOG_NEWLINE
)
1484 text
[textlen
++] = '\n';
1485 /* got everything, release buffer */
1491 asmlinkage
int vprintk_emit(int facility
, int level
,
1492 const char *dict
, size_t dictlen
,
1493 const char *fmt
, va_list args
)
1495 static int recursion_bug
;
1496 static char textbuf
[LOG_LINE_MAX
];
1497 char *text
= textbuf
;
1499 enum log_flags lflags
= 0;
1500 unsigned long flags
;
1502 int printed_len
= 0;
1504 boot_delay_msec(level
);
1507 /* This stops the holder of console_sem just where we want him */
1508 local_irq_save(flags
);
1509 this_cpu
= smp_processor_id();
1512 * Ouch, printk recursed into itself!
1514 if (unlikely(logbuf_cpu
== this_cpu
)) {
1516 * If a crash is occurring during printk() on this CPU,
1517 * then try to get the crash message out but make sure
1518 * we can't deadlock. Otherwise just return to avoid the
1519 * recursion and return - but flag the recursion so that
1520 * it can be printed at the next appropriate moment:
1522 if (!oops_in_progress
&& !lockdep_recursing(current
)) {
1524 goto out_restore_irqs
;
1530 raw_spin_lock(&logbuf_lock
);
1531 logbuf_cpu
= this_cpu
;
1533 if (recursion_bug
) {
1534 static const char recursion_msg
[] =
1535 "BUG: recent printk recursion!";
1538 printed_len
+= strlen(recursion_msg
);
1539 /* emit KERN_CRIT message */
1540 log_store(0, 2, LOG_PREFIX
|LOG_NEWLINE
, 0,
1541 NULL
, 0, recursion_msg
, printed_len
);
1545 * The printf needs to come first; we need the syslog
1546 * prefix which might be passed-in as a parameter.
1548 text_len
= vscnprintf(text
, sizeof(textbuf
), fmt
, args
);
1550 /* mark and strip a trailing newline */
1551 if (text_len
&& text
[text_len
-1] == '\n') {
1553 lflags
|= LOG_NEWLINE
;
1556 /* strip kernel syslog prefix and extract log level or control flags */
1557 if (facility
== 0) {
1558 int kern_level
= printk_get_level(text
);
1561 const char *end_of_header
= printk_skip_level(text
);
1562 switch (kern_level
) {
1565 level
= kern_level
- '0';
1566 case 'd': /* KERN_DEFAULT */
1567 lflags
|= LOG_PREFIX
;
1568 case 'c': /* KERN_CONT */
1571 text_len
-= end_of_header
- text
;
1572 text
= (char *)end_of_header
;
1577 level
= default_message_loglevel
;
1580 lflags
|= LOG_PREFIX
|LOG_NEWLINE
;
1582 if (!(lflags
& LOG_NEWLINE
)) {
1584 * Flush the conflicting buffer. An earlier newline was missing,
1585 * or another task also prints continuation lines.
1587 if (cont
.len
&& (lflags
& LOG_PREFIX
|| cont
.owner
!= current
))
1588 cont_flush(LOG_NEWLINE
);
1590 /* buffer line if possible, otherwise store it right away */
1591 if (!cont_add(facility
, level
, text
, text_len
))
1592 log_store(facility
, level
, lflags
| LOG_CONT
, 0,
1593 dict
, dictlen
, text
, text_len
);
1595 bool stored
= false;
1598 * If an earlier newline was missing and it was the same task,
1599 * either merge it with the current buffer and flush, or if
1600 * there was a race with interrupts (prefix == true) then just
1601 * flush it out and store this line separately.
1603 if (cont
.len
&& cont
.owner
== current
) {
1604 if (!(lflags
& LOG_PREFIX
))
1605 stored
= cont_add(facility
, level
, text
, text_len
);
1606 cont_flush(LOG_NEWLINE
);
1610 log_store(facility
, level
, lflags
, 0,
1611 dict
, dictlen
, text
, text_len
);
1613 printed_len
+= text_len
;
1616 * Try to acquire and then immediately release the console semaphore.
1617 * The release will print out buffers and wake up /dev/kmsg and syslog()
1620 * The console_trylock_for_printk() function will release 'logbuf_lock'
1621 * regardless of whether it actually gets the console semaphore or not.
1623 if (console_trylock_for_printk(this_cpu
))
1628 local_irq_restore(flags
);
1632 EXPORT_SYMBOL(vprintk_emit
);
1634 asmlinkage
int vprintk(const char *fmt
, va_list args
)
1636 return vprintk_emit(0, -1, NULL
, 0, fmt
, args
);
1638 EXPORT_SYMBOL(vprintk
);
1640 asmlinkage
int printk_emit(int facility
, int level
,
1641 const char *dict
, size_t dictlen
,
1642 const char *fmt
, ...)
1647 va_start(args
, fmt
);
1648 r
= vprintk_emit(facility
, level
, dict
, dictlen
, fmt
, args
);
1653 EXPORT_SYMBOL(printk_emit
);
1656 * printk - print a kernel message
1657 * @fmt: format string
1659 * This is printk(). It can be called from any context. We want it to work.
1661 * We try to grab the console_lock. If we succeed, it's easy - we log the
1662 * output and call the console drivers. If we fail to get the semaphore, we
1663 * place the output into the log buffer and return. The current holder of
1664 * the console_sem will notice the new output in console_unlock(); and will
1665 * send it to the consoles before releasing the lock.
1667 * One effect of this deferred printing is that code which calls printk() and
1668 * then changes console_loglevel may break. This is because console_loglevel
1669 * is inspected when the actual printing occurs.
1674 * See the vsnprintf() documentation for format string extensions over C99.
1676 asmlinkage
int printk(const char *fmt
, ...)
1681 #ifdef CONFIG_KGDB_KDB
1682 if (unlikely(kdb_trap_printk
)) {
1683 va_start(args
, fmt
);
1684 r
= vkdb_printf(fmt
, args
);
1689 va_start(args
, fmt
);
1690 r
= vprintk_emit(0, -1, NULL
, 0, fmt
, args
);
1695 EXPORT_SYMBOL(printk
);
1697 #else /* CONFIG_PRINTK */
1699 #define LOG_LINE_MAX 0
1700 #define PREFIX_MAX 0
1701 #define LOG_LINE_MAX 0
1702 static u64 syslog_seq
;
1703 static u32 syslog_idx
;
1704 static u64 console_seq
;
1705 static u32 console_idx
;
1706 static enum log_flags syslog_prev
;
1707 static u64 log_first_seq
;
1708 static u32 log_first_idx
;
1709 static u64 log_next_seq
;
1710 static enum log_flags console_prev
;
1711 static struct cont
{
1717 static struct log
*log_from_idx(u32 idx
) { return NULL
; }
1718 static u32
log_next(u32 idx
) { return 0; }
1719 static void call_console_drivers(int level
, const char *text
, size_t len
) {}
1720 static size_t msg_print_text(const struct log
*msg
, enum log_flags prev
,
1721 bool syslog
, char *buf
, size_t size
) { return 0; }
1722 static size_t cont_print_text(char *text
, size_t size
) { return 0; }
1724 #endif /* CONFIG_PRINTK */
1726 #ifdef CONFIG_EARLY_PRINTK
1727 struct console
*early_console
;
1729 void early_vprintk(const char *fmt
, va_list ap
)
1731 if (early_console
) {
1733 int n
= vscnprintf(buf
, sizeof(buf
), fmt
, ap
);
1735 early_console
->write(early_console
, buf
, n
);
1739 asmlinkage
void early_printk(const char *fmt
, ...)
1744 early_vprintk(fmt
, ap
);
1749 static int __add_preferred_console(char *name
, int idx
, char *options
,
1752 struct console_cmdline
*c
;
1756 * See if this tty is not yet registered, and
1757 * if we have a slot free.
1759 for (i
= 0; i
< MAX_CMDLINECONSOLES
&& console_cmdline
[i
].name
[0]; i
++)
1760 if (strcmp(console_cmdline
[i
].name
, name
) == 0 &&
1761 console_cmdline
[i
].index
== idx
) {
1763 selected_console
= i
;
1766 if (i
== MAX_CMDLINECONSOLES
)
1769 selected_console
= i
;
1770 c
= &console_cmdline
[i
];
1771 strlcpy(c
->name
, name
, sizeof(c
->name
));
1772 c
->options
= options
;
1773 braille_set_options(c
, brl_options
);
1779 * Set up a list of consoles. Called from init/main.c
1781 static int __init
console_setup(char *str
)
1783 char buf
[sizeof(console_cmdline
[0].name
) + 4]; /* 4 for index */
1784 char *s
, *options
, *brl_options
= NULL
;
1787 if (_braille_console_setup(&str
, &brl_options
))
1791 * Decode str into name, index, options.
1793 if (str
[0] >= '0' && str
[0] <= '9') {
1794 strcpy(buf
, "ttyS");
1795 strncpy(buf
+ 4, str
, sizeof(buf
) - 5);
1797 strncpy(buf
, str
, sizeof(buf
) - 1);
1799 buf
[sizeof(buf
) - 1] = 0;
1800 if ((options
= strchr(str
, ',')) != NULL
)
1803 if (!strcmp(str
, "ttya"))
1804 strcpy(buf
, "ttyS0");
1805 if (!strcmp(str
, "ttyb"))
1806 strcpy(buf
, "ttyS1");
1808 for (s
= buf
; *s
; s
++)
1809 if ((*s
>= '0' && *s
<= '9') || *s
== ',')
1811 idx
= simple_strtoul(s
, NULL
, 10);
1814 __add_preferred_console(buf
, idx
, options
, brl_options
);
1815 console_set_on_cmdline
= 1;
1818 __setup("console=", console_setup
);
1821 * add_preferred_console - add a device to the list of preferred consoles.
1822 * @name: device name
1823 * @idx: device index
1824 * @options: options for this console
1826 * The last preferred console added will be used for kernel messages
1827 * and stdin/out/err for init. Normally this is used by console_setup
1828 * above to handle user-supplied console arguments; however it can also
1829 * be used by arch-specific code either to override the user or more
1830 * commonly to provide a default console (ie from PROM variables) when
1831 * the user has not supplied one.
1833 int add_preferred_console(char *name
, int idx
, char *options
)
1835 return __add_preferred_console(name
, idx
, options
, NULL
);
1838 int update_console_cmdline(char *name
, int idx
, char *name_new
, int idx_new
, char *options
)
1840 struct console_cmdline
*c
;
1843 for (i
= 0; i
< MAX_CMDLINECONSOLES
&& console_cmdline
[i
].name
[0]; i
++)
1844 if (strcmp(console_cmdline
[i
].name
, name
) == 0 &&
1845 console_cmdline
[i
].index
== idx
) {
1846 c
= &console_cmdline
[i
];
1847 strlcpy(c
->name
, name_new
, sizeof(c
->name
));
1848 c
->name
[sizeof(c
->name
) - 1] = 0;
1849 c
->options
= options
;
1857 bool console_suspend_enabled
= 1;
1858 EXPORT_SYMBOL(console_suspend_enabled
);
1860 static int __init
console_suspend_disable(char *str
)
1862 console_suspend_enabled
= 0;
1865 __setup("no_console_suspend", console_suspend_disable
);
1866 module_param_named(console_suspend
, console_suspend_enabled
,
1867 bool, S_IRUGO
| S_IWUSR
);
1868 MODULE_PARM_DESC(console_suspend
, "suspend console during suspend"
1869 " and hibernate operations");
1872 * suspend_console - suspend the console subsystem
1874 * This disables printk() while we go into suspend states
1876 void suspend_console(void)
1878 if (!console_suspend_enabled
)
1880 printk("Suspending console(s) (use no_console_suspend to debug)\n");
1882 console_suspended
= 1;
1886 void resume_console(void)
1888 if (!console_suspend_enabled
)
1891 console_suspended
= 0;
1896 * console_cpu_notify - print deferred console messages after CPU hotplug
1897 * @self: notifier struct
1898 * @action: CPU hotplug event
1901 * If printk() is called from a CPU that is not online yet, the messages
1902 * will be spooled but will not show up on the console. This function is
1903 * called when a new CPU comes online (or fails to come up), and ensures
1904 * that any such output gets printed.
1906 static int console_cpu_notify(struct notifier_block
*self
,
1907 unsigned long action
, void *hcpu
)
1912 case CPU_DOWN_FAILED
:
1913 case CPU_UP_CANCELED
:
1921 * console_lock - lock the console system for exclusive use.
1923 * Acquires a lock which guarantees that the caller has
1924 * exclusive access to the console system and the console_drivers list.
1926 * Can sleep, returns nothing.
1928 void console_lock(void)
1933 if (console_suspended
)
1936 console_may_schedule
= 1;
1937 mutex_acquire(&console_lock_dep_map
, 0, 0, _RET_IP_
);
1939 EXPORT_SYMBOL(console_lock
);
1942 * console_trylock - try to lock the console system for exclusive use.
1944 * Tried to acquire a lock which guarantees that the caller has
1945 * exclusive access to the console system and the console_drivers list.
1947 * returns 1 on success, and 0 on failure to acquire the lock.
1949 int console_trylock(void)
1951 if (down_trylock(&console_sem
))
1953 if (console_suspended
) {
1958 console_may_schedule
= 0;
1959 mutex_acquire(&console_lock_dep_map
, 0, 1, _RET_IP_
);
1962 EXPORT_SYMBOL(console_trylock
);
1964 int is_console_locked(void)
1966 return console_locked
;
1969 static void console_cont_flush(char *text
, size_t size
)
1971 unsigned long flags
;
1974 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
1980 * We still queue earlier records, likely because the console was
1981 * busy. The earlier ones need to be printed before this one, we
1982 * did not flush any fragment so far, so just let it queue up.
1984 if (console_seq
< log_next_seq
&& !cont
.cons
)
1987 len
= cont_print_text(text
, size
);
1988 raw_spin_unlock(&logbuf_lock
);
1989 stop_critical_timings();
1990 call_console_drivers(cont
.level
, text
, len
);
1991 start_critical_timings();
1992 local_irq_restore(flags
);
1995 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
1999 * console_unlock - unlock the console system
2001 * Releases the console_lock which the caller holds on the console system
2002 * and the console driver list.
2004 * While the console_lock was held, console output may have been buffered
2005 * by printk(). If this is the case, console_unlock(); emits
2006 * the output prior to releasing the lock.
2008 * If there is output waiting, we wake /dev/kmsg and syslog() users.
2010 * console_unlock(); may be called from any context.
2012 void console_unlock(void)
2014 static char text
[LOG_LINE_MAX
+ PREFIX_MAX
];
2015 static u64 seen_seq
;
2016 unsigned long flags
;
2017 bool wake_klogd
= false;
2020 if (console_suspended
) {
2025 console_may_schedule
= 0;
2027 /* flush buffered message fragment immediately to console */
2028 console_cont_flush(text
, sizeof(text
));
2035 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2036 if (seen_seq
!= log_next_seq
) {
2038 seen_seq
= log_next_seq
;
2041 if (console_seq
< log_first_seq
) {
2042 /* messages are gone, move to first one */
2043 console_seq
= log_first_seq
;
2044 console_idx
= log_first_idx
;
2048 if (console_seq
== log_next_seq
)
2051 msg
= log_from_idx(console_idx
);
2052 if (msg
->flags
& LOG_NOCONS
) {
2054 * Skip record we have buffered and already printed
2055 * directly to the console when we received it.
2057 console_idx
= log_next(console_idx
);
2060 * We will get here again when we register a new
2061 * CON_PRINTBUFFER console. Clear the flag so we
2062 * will properly dump everything later.
2064 msg
->flags
&= ~LOG_NOCONS
;
2065 console_prev
= msg
->flags
;
2070 len
= msg_print_text(msg
, console_prev
, false,
2071 text
, sizeof(text
));
2072 console_idx
= log_next(console_idx
);
2074 console_prev
= msg
->flags
;
2075 raw_spin_unlock(&logbuf_lock
);
2077 stop_critical_timings(); /* don't trace print latency */
2078 call_console_drivers(level
, text
, len
);
2079 start_critical_timings();
2080 local_irq_restore(flags
);
2083 mutex_release(&console_lock_dep_map
, 1, _RET_IP_
);
2085 /* Release the exclusive_console once it is used */
2086 if (unlikely(exclusive_console
))
2087 exclusive_console
= NULL
;
2089 raw_spin_unlock(&logbuf_lock
);
2094 * Someone could have filled up the buffer again, so re-check if there's
2095 * something to flush. In case we cannot trylock the console_sem again,
2096 * there's a new owner and the console_unlock() from them will do the
2097 * flush, no worries.
2099 raw_spin_lock(&logbuf_lock
);
2100 retry
= console_seq
!= log_next_seq
;
2101 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2103 if (retry
&& console_trylock())
2109 EXPORT_SYMBOL(console_unlock
);
2112 * console_conditional_schedule - yield the CPU if required
2114 * If the console code is currently allowed to sleep, and
2115 * if this CPU should yield the CPU to another task, do
2118 * Must be called within console_lock();.
2120 void __sched
console_conditional_schedule(void)
2122 if (console_may_schedule
)
2125 EXPORT_SYMBOL(console_conditional_schedule
);
2127 void console_unblank(void)
2132 * console_unblank can no longer be called in interrupt context unless
2133 * oops_in_progress is set to 1..
2135 if (oops_in_progress
) {
2136 if (down_trylock(&console_sem
) != 0)
2142 console_may_schedule
= 0;
2144 if ((c
->flags
& CON_ENABLED
) && c
->unblank
)
2150 * Return the console tty driver structure and its associated index
2152 struct tty_driver
*console_device(int *index
)
2155 struct tty_driver
*driver
= NULL
;
2158 for_each_console(c
) {
2161 driver
= c
->device(c
, index
);
2170 * Prevent further output on the passed console device so that (for example)
2171 * serial drivers can disable console output before suspending a port, and can
2172 * re-enable output afterwards.
2174 void console_stop(struct console
*console
)
2177 console
->flags
&= ~CON_ENABLED
;
2180 EXPORT_SYMBOL(console_stop
);
2182 void console_start(struct console
*console
)
2185 console
->flags
|= CON_ENABLED
;
2188 EXPORT_SYMBOL(console_start
);
2190 static int __read_mostly keep_bootcon
;
2192 static int __init
keep_bootcon_setup(char *str
)
2195 printk(KERN_INFO
"debug: skip boot console de-registration.\n");
2200 early_param("keep_bootcon", keep_bootcon_setup
);
2203 * The console driver calls this routine during kernel initialization
2204 * to register the console printing procedure with printk() and to
2205 * print any messages that were printed by the kernel before the
2206 * console driver was initialized.
2208 * This can happen pretty early during the boot process (because of
2209 * early_printk) - sometimes before setup_arch() completes - be careful
2210 * of what kernel features are used - they may not be initialised yet.
2212 * There are two types of consoles - bootconsoles (early_printk) and
2213 * "real" consoles (everything which is not a bootconsole) which are
2214 * handled differently.
2215 * - Any number of bootconsoles can be registered at any time.
2216 * - As soon as a "real" console is registered, all bootconsoles
2217 * will be unregistered automatically.
2218 * - Once a "real" console is registered, any attempt to register a
2219 * bootconsoles will be rejected
2221 void register_console(struct console
*newcon
)
2224 unsigned long flags
;
2225 struct console
*bcon
= NULL
;
2228 * before we register a new CON_BOOT console, make sure we don't
2229 * already have a valid console
2231 if (console_drivers
&& newcon
->flags
& CON_BOOT
) {
2232 /* find the last or real console */
2233 for_each_console(bcon
) {
2234 if (!(bcon
->flags
& CON_BOOT
)) {
2235 printk(KERN_INFO
"Too late to register bootconsole %s%d\n",
2236 newcon
->name
, newcon
->index
);
2242 if (console_drivers
&& console_drivers
->flags
& CON_BOOT
)
2243 bcon
= console_drivers
;
2245 if (preferred_console
< 0 || bcon
|| !console_drivers
)
2246 preferred_console
= selected_console
;
2248 if (newcon
->early_setup
)
2249 newcon
->early_setup();
2252 * See if we want to use this console driver. If we
2253 * didn't select a console we take the first one
2254 * that registers here.
2256 if (preferred_console
< 0) {
2257 if (newcon
->index
< 0)
2259 if (newcon
->setup
== NULL
||
2260 newcon
->setup(newcon
, NULL
) == 0) {
2261 newcon
->flags
|= CON_ENABLED
;
2262 if (newcon
->device
) {
2263 newcon
->flags
|= CON_CONSDEV
;
2264 preferred_console
= 0;
2270 * See if this console matches one we selected on
2273 for (i
= 0; i
< MAX_CMDLINECONSOLES
&& console_cmdline
[i
].name
[0];
2275 if (strcmp(console_cmdline
[i
].name
, newcon
->name
) != 0)
2277 if (newcon
->index
>= 0 &&
2278 newcon
->index
!= console_cmdline
[i
].index
)
2280 if (newcon
->index
< 0)
2281 newcon
->index
= console_cmdline
[i
].index
;
2283 if (_braille_register_console(newcon
, &console_cmdline
[i
]))
2286 if (newcon
->setup
&&
2287 newcon
->setup(newcon
, console_cmdline
[i
].options
) != 0)
2289 newcon
->flags
|= CON_ENABLED
;
2290 newcon
->index
= console_cmdline
[i
].index
;
2291 if (i
== selected_console
) {
2292 newcon
->flags
|= CON_CONSDEV
;
2293 preferred_console
= selected_console
;
2298 if (!(newcon
->flags
& CON_ENABLED
))
2302 * If we have a bootconsole, and are switching to a real console,
2303 * don't print everything out again, since when the boot console, and
2304 * the real console are the same physical device, it's annoying to
2305 * see the beginning boot messages twice
2307 if (bcon
&& ((newcon
->flags
& (CON_CONSDEV
| CON_BOOT
)) == CON_CONSDEV
))
2308 newcon
->flags
&= ~CON_PRINTBUFFER
;
2311 * Put this console in the list - keep the
2312 * preferred driver at the head of the list.
2315 if ((newcon
->flags
& CON_CONSDEV
) || console_drivers
== NULL
) {
2316 newcon
->next
= console_drivers
;
2317 console_drivers
= newcon
;
2319 newcon
->next
->flags
&= ~CON_CONSDEV
;
2321 newcon
->next
= console_drivers
->next
;
2322 console_drivers
->next
= newcon
;
2324 if (newcon
->flags
& CON_PRINTBUFFER
) {
2326 * console_unlock(); will print out the buffered messages
2329 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2330 console_seq
= syslog_seq
;
2331 console_idx
= syslog_idx
;
2332 console_prev
= syslog_prev
;
2333 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2335 * We're about to replay the log buffer. Only do this to the
2336 * just-registered console to avoid excessive message spam to
2337 * the already-registered consoles.
2339 exclusive_console
= newcon
;
2342 console_sysfs_notify();
2345 * By unregistering the bootconsoles after we enable the real console
2346 * we get the "console xxx enabled" message on all the consoles -
2347 * boot consoles, real consoles, etc - this is to ensure that end
2348 * users know there might be something in the kernel's log buffer that
2349 * went to the bootconsole (that they do not see on the real console)
2352 ((newcon
->flags
& (CON_CONSDEV
| CON_BOOT
)) == CON_CONSDEV
) &&
2354 /* we need to iterate through twice, to make sure we print
2355 * everything out, before we unregister the console(s)
2357 printk(KERN_INFO
"console [%s%d] enabled, bootconsole disabled\n",
2358 newcon
->name
, newcon
->index
);
2359 for_each_console(bcon
)
2360 if (bcon
->flags
& CON_BOOT
)
2361 unregister_console(bcon
);
2363 printk(KERN_INFO
"%sconsole [%s%d] enabled\n",
2364 (newcon
->flags
& CON_BOOT
) ? "boot" : "" ,
2365 newcon
->name
, newcon
->index
);
2368 EXPORT_SYMBOL(register_console
);
2370 int unregister_console(struct console
*console
)
2372 struct console
*a
, *b
;
2375 res
= _braille_unregister_console(console
);
2381 if (console_drivers
== console
) {
2382 console_drivers
=console
->next
;
2384 } else if (console_drivers
) {
2385 for (a
=console_drivers
->next
, b
=console_drivers
;
2386 a
; b
=a
, a
=b
->next
) {
2396 * If this isn't the last console and it has CON_CONSDEV set, we
2397 * need to set it on the next preferred console.
2399 if (console_drivers
!= NULL
&& console
->flags
& CON_CONSDEV
)
2400 console_drivers
->flags
|= CON_CONSDEV
;
2403 console_sysfs_notify();
2406 EXPORT_SYMBOL(unregister_console
);
2408 static int __init
printk_late_init(void)
2410 struct console
*con
;
2412 for_each_console(con
) {
2413 if (!keep_bootcon
&& con
->flags
& CON_BOOT
) {
2414 printk(KERN_INFO
"turn off boot console %s%d\n",
2415 con
->name
, con
->index
);
2416 unregister_console(con
);
2419 hotcpu_notifier(console_cpu_notify
, 0);
2422 late_initcall(printk_late_init
);
2424 #if defined CONFIG_PRINTK
2426 * Delayed printk version, for scheduler-internal messages:
2428 #define PRINTK_BUF_SIZE 512
2430 #define PRINTK_PENDING_WAKEUP 0x01
2431 #define PRINTK_PENDING_SCHED 0x02
2433 static DEFINE_PER_CPU(int, printk_pending
);
2434 static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE
], printk_sched_buf
);
2436 static void wake_up_klogd_work_func(struct irq_work
*irq_work
)
2438 int pending
= __this_cpu_xchg(printk_pending
, 0);
2440 if (pending
& PRINTK_PENDING_SCHED
) {
2441 char *buf
= __get_cpu_var(printk_sched_buf
);
2442 printk(KERN_WARNING
"[sched_delayed] %s", buf
);
2445 if (pending
& PRINTK_PENDING_WAKEUP
)
2446 wake_up_interruptible(&log_wait
);
2449 static DEFINE_PER_CPU(struct irq_work
, wake_up_klogd_work
) = {
2450 .func
= wake_up_klogd_work_func
,
2451 .flags
= IRQ_WORK_LAZY
,
2454 void wake_up_klogd(void)
2457 if (waitqueue_active(&log_wait
)) {
2458 this_cpu_or(printk_pending
, PRINTK_PENDING_WAKEUP
);
2459 irq_work_queue(&__get_cpu_var(wake_up_klogd_work
));
2464 int printk_sched(const char *fmt
, ...)
2466 unsigned long flags
;
2471 local_irq_save(flags
);
2472 buf
= __get_cpu_var(printk_sched_buf
);
2474 va_start(args
, fmt
);
2475 r
= vsnprintf(buf
, PRINTK_BUF_SIZE
, fmt
, args
);
2478 __this_cpu_or(printk_pending
, PRINTK_PENDING_SCHED
);
2479 irq_work_queue(&__get_cpu_var(wake_up_klogd_work
));
2480 local_irq_restore(flags
);
2486 * printk rate limiting, lifted from the networking subsystem.
2488 * This enforces a rate limit: not more than 10 kernel messages
2489 * every 5s to make a denial-of-service attack impossible.
2491 DEFINE_RATELIMIT_STATE(printk_ratelimit_state
, 5 * HZ
, 10);
2493 int __printk_ratelimit(const char *func
)
2495 return ___ratelimit(&printk_ratelimit_state
, func
);
2497 EXPORT_SYMBOL(__printk_ratelimit
);
2500 * printk_timed_ratelimit - caller-controlled printk ratelimiting
2501 * @caller_jiffies: pointer to caller's state
2502 * @interval_msecs: minimum interval between prints
2504 * printk_timed_ratelimit() returns true if more than @interval_msecs
2505 * milliseconds have elapsed since the last time printk_timed_ratelimit()
2508 bool printk_timed_ratelimit(unsigned long *caller_jiffies
,
2509 unsigned int interval_msecs
)
2511 if (*caller_jiffies
== 0
2512 || !time_in_range(jiffies
, *caller_jiffies
,
2514 + msecs_to_jiffies(interval_msecs
))) {
2515 *caller_jiffies
= jiffies
;
2520 EXPORT_SYMBOL(printk_timed_ratelimit
);
2522 static DEFINE_SPINLOCK(dump_list_lock
);
2523 static LIST_HEAD(dump_list
);
2526 * kmsg_dump_register - register a kernel log dumper.
2527 * @dumper: pointer to the kmsg_dumper structure
2529 * Adds a kernel log dumper to the system. The dump callback in the
2530 * structure will be called when the kernel oopses or panics and must be
2531 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
2533 int kmsg_dump_register(struct kmsg_dumper
*dumper
)
2535 unsigned long flags
;
2538 /* The dump callback needs to be set */
2542 spin_lock_irqsave(&dump_list_lock
, flags
);
2543 /* Don't allow registering multiple times */
2544 if (!dumper
->registered
) {
2545 dumper
->registered
= 1;
2546 list_add_tail_rcu(&dumper
->list
, &dump_list
);
2549 spin_unlock_irqrestore(&dump_list_lock
, flags
);
2553 EXPORT_SYMBOL_GPL(kmsg_dump_register
);
2556 * kmsg_dump_unregister - unregister a kmsg dumper.
2557 * @dumper: pointer to the kmsg_dumper structure
2559 * Removes a dump device from the system. Returns zero on success and
2560 * %-EINVAL otherwise.
2562 int kmsg_dump_unregister(struct kmsg_dumper
*dumper
)
2564 unsigned long flags
;
2567 spin_lock_irqsave(&dump_list_lock
, flags
);
2568 if (dumper
->registered
) {
2569 dumper
->registered
= 0;
2570 list_del_rcu(&dumper
->list
);
2573 spin_unlock_irqrestore(&dump_list_lock
, flags
);
2578 EXPORT_SYMBOL_GPL(kmsg_dump_unregister
);
2580 static bool always_kmsg_dump
;
2581 module_param_named(always_kmsg_dump
, always_kmsg_dump
, bool, S_IRUGO
| S_IWUSR
);
2584 * kmsg_dump - dump kernel log to kernel message dumpers.
2585 * @reason: the reason (oops, panic etc) for dumping
2587 * Call each of the registered dumper's dump() callback, which can
2588 * retrieve the kmsg records with kmsg_dump_get_line() or
2589 * kmsg_dump_get_buffer().
2591 void kmsg_dump(enum kmsg_dump_reason reason
)
2593 struct kmsg_dumper
*dumper
;
2594 unsigned long flags
;
2596 if ((reason
> KMSG_DUMP_OOPS
) && !always_kmsg_dump
)
2600 list_for_each_entry_rcu(dumper
, &dump_list
, list
) {
2601 if (dumper
->max_reason
&& reason
> dumper
->max_reason
)
2604 /* initialize iterator with data about the stored records */
2605 dumper
->active
= true;
2607 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2608 dumper
->cur_seq
= clear_seq
;
2609 dumper
->cur_idx
= clear_idx
;
2610 dumper
->next_seq
= log_next_seq
;
2611 dumper
->next_idx
= log_next_idx
;
2612 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2614 /* invoke dumper which will iterate over records */
2615 dumper
->dump(dumper
, reason
);
2617 /* reset iterator */
2618 dumper
->active
= false;
2624 * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
2625 * @dumper: registered kmsg dumper
2626 * @syslog: include the "<4>" prefixes
2627 * @line: buffer to copy the line to
2628 * @size: maximum size of the buffer
2629 * @len: length of line placed into buffer
2631 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2632 * record, and copy one record into the provided buffer.
2634 * Consecutive calls will return the next available record moving
2635 * towards the end of the buffer with the youngest messages.
2637 * A return value of FALSE indicates that there are no more records to
2640 * The function is similar to kmsg_dump_get_line(), but grabs no locks.
2642 bool kmsg_dump_get_line_nolock(struct kmsg_dumper
*dumper
, bool syslog
,
2643 char *line
, size_t size
, size_t *len
)
2649 if (!dumper
->active
)
2652 if (dumper
->cur_seq
< log_first_seq
) {
2653 /* messages are gone, move to first available one */
2654 dumper
->cur_seq
= log_first_seq
;
2655 dumper
->cur_idx
= log_first_idx
;
2659 if (dumper
->cur_seq
>= log_next_seq
)
2662 msg
= log_from_idx(dumper
->cur_idx
);
2663 l
= msg_print_text(msg
, 0, syslog
, line
, size
);
2665 dumper
->cur_idx
= log_next(dumper
->cur_idx
);
2675 * kmsg_dump_get_line - retrieve one kmsg log line
2676 * @dumper: registered kmsg dumper
2677 * @syslog: include the "<4>" prefixes
2678 * @line: buffer to copy the line to
2679 * @size: maximum size of the buffer
2680 * @len: length of line placed into buffer
2682 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2683 * record, and copy one record into the provided buffer.
2685 * Consecutive calls will return the next available record moving
2686 * towards the end of the buffer with the youngest messages.
2688 * A return value of FALSE indicates that there are no more records to
2691 bool kmsg_dump_get_line(struct kmsg_dumper
*dumper
, bool syslog
,
2692 char *line
, size_t size
, size_t *len
)
2694 unsigned long flags
;
2697 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2698 ret
= kmsg_dump_get_line_nolock(dumper
, syslog
, line
, size
, len
);
2699 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2703 EXPORT_SYMBOL_GPL(kmsg_dump_get_line
);
2706 * kmsg_dump_get_buffer - copy kmsg log lines
2707 * @dumper: registered kmsg dumper
2708 * @syslog: include the "<4>" prefixes
2709 * @buf: buffer to copy the line to
2710 * @size: maximum size of the buffer
2711 * @len: length of line placed into buffer
2713 * Start at the end of the kmsg buffer and fill the provided buffer
2714 * with as many of the the *youngest* kmsg records that fit into it.
2715 * If the buffer is large enough, all available kmsg records will be
2716 * copied with a single call.
2718 * Consecutive calls will fill the buffer with the next block of
2719 * available older records, not including the earlier retrieved ones.
2721 * A return value of FALSE indicates that there are no more records to
2724 bool kmsg_dump_get_buffer(struct kmsg_dumper
*dumper
, bool syslog
,
2725 char *buf
, size_t size
, size_t *len
)
2727 unsigned long flags
;
2732 enum log_flags prev
;
2736 if (!dumper
->active
)
2739 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2740 if (dumper
->cur_seq
< log_first_seq
) {
2741 /* messages are gone, move to first available one */
2742 dumper
->cur_seq
= log_first_seq
;
2743 dumper
->cur_idx
= log_first_idx
;
2747 if (dumper
->cur_seq
>= dumper
->next_seq
) {
2748 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2752 /* calculate length of entire buffer */
2753 seq
= dumper
->cur_seq
;
2754 idx
= dumper
->cur_idx
;
2756 while (seq
< dumper
->next_seq
) {
2757 struct log
*msg
= log_from_idx(idx
);
2759 l
+= msg_print_text(msg
, prev
, true, NULL
, 0);
2760 idx
= log_next(idx
);
2765 /* move first record forward until length fits into the buffer */
2766 seq
= dumper
->cur_seq
;
2767 idx
= dumper
->cur_idx
;
2769 while (l
> size
&& seq
< dumper
->next_seq
) {
2770 struct log
*msg
= log_from_idx(idx
);
2772 l
-= msg_print_text(msg
, prev
, true, NULL
, 0);
2773 idx
= log_next(idx
);
2778 /* last message in next interation */
2784 while (seq
< dumper
->next_seq
) {
2785 struct log
*msg
= log_from_idx(idx
);
2787 l
+= msg_print_text(msg
, prev
, syslog
, buf
+ l
, size
- l
);
2788 idx
= log_next(idx
);
2793 dumper
->next_seq
= next_seq
;
2794 dumper
->next_idx
= next_idx
;
2796 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2802 EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer
);
2805 * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
2806 * @dumper: registered kmsg dumper
2808 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2809 * kmsg_dump_get_buffer() can be called again and used multiple
2810 * times within the same dumper.dump() callback.
2812 * The function is similar to kmsg_dump_rewind(), but grabs no locks.
2814 void kmsg_dump_rewind_nolock(struct kmsg_dumper
*dumper
)
2816 dumper
->cur_seq
= clear_seq
;
2817 dumper
->cur_idx
= clear_idx
;
2818 dumper
->next_seq
= log_next_seq
;
2819 dumper
->next_idx
= log_next_idx
;
2823 * kmsg_dump_rewind - reset the interator
2824 * @dumper: registered kmsg dumper
2826 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2827 * kmsg_dump_get_buffer() can be called again and used multiple
2828 * times within the same dumper.dump() callback.
2830 void kmsg_dump_rewind(struct kmsg_dumper
*dumper
)
2832 unsigned long flags
;
2834 raw_spin_lock_irqsave(&logbuf_lock
, flags
);
2835 kmsg_dump_rewind_nolock(dumper
);
2836 raw_spin_unlock_irqrestore(&logbuf_lock
, flags
);
2838 EXPORT_SYMBOL_GPL(kmsg_dump_rewind
);
2840 static char dump_stack_arch_desc_str
[128];
2843 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
2844 * @fmt: printf-style format string
2845 * @...: arguments for the format string
2847 * The configured string will be printed right after utsname during task
2848 * dumps. Usually used to add arch-specific system identifiers. If an
2849 * arch wants to make use of such an ID string, it should initialize this
2850 * as soon as possible during boot.
2852 void __init
dump_stack_set_arch_desc(const char *fmt
, ...)
2856 va_start(args
, fmt
);
2857 vsnprintf(dump_stack_arch_desc_str
, sizeof(dump_stack_arch_desc_str
),
2863 * dump_stack_print_info - print generic debug info for dump_stack()
2864 * @log_lvl: log level
2866 * Arch-specific dump_stack() implementations can use this function to
2867 * print out the same debug information as the generic dump_stack().
2869 void dump_stack_print_info(const char *log_lvl
)
2871 printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
2872 log_lvl
, raw_smp_processor_id(), current
->pid
, current
->comm
,
2873 print_tainted(), init_utsname()->release
,
2874 (int)strcspn(init_utsname()->version
, " "),
2875 init_utsname()->version
);
2877 if (dump_stack_arch_desc_str
[0] != '\0')
2878 printk("%sHardware name: %s\n",
2879 log_lvl
, dump_stack_arch_desc_str
);
2881 print_worker_info(log_lvl
, current
);
2885 * show_regs_print_info - print generic debug info for show_regs()
2886 * @log_lvl: log level
2888 * show_regs() implementations can use this function to print out generic
2889 * debug information.
2891 void show_regs_print_info(const char *log_lvl
)
2893 dump_stack_print_info(log_lvl
);
2895 printk("%stask: %p ti: %p task.ti: %p\n",
2896 log_lvl
, current
, current_thread_info(),
2897 task_thread_info(current
));