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 #ifdef CONFIG_EARLY_PRINTK_DIRECT
55 extern void printascii(char *);
58 /* printk's without a loglevel use this.. */
59 #define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
61 /* We show everything that is MORE important than this.. */
62 #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
63 #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
65 int console_printk[5] = {
66 DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
67 DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
68 MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */
69 DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
70 DEFAULT_MESSAGE_LOGLEVEL, /* default_devkmsg_loglevel */
74 * Low level drivers may need that to know if they can schedule in
75 * their unblank() callback or not. So let's export it.
78 EXPORT_SYMBOL(oops_in_progress);
81 * console_sem protects the console_drivers list, and also
82 * provides serialisation for access to the entire console
85 static DEFINE_SEMAPHORE(console_sem);
86 struct console *console_drivers;
87 EXPORT_SYMBOL_GPL(console_drivers);
90 static struct lockdep_map console_lock_dep_map = {
91 .name = "console_lock"
96 * This is used for debugging the mess that is the VT code by
97 * keeping track if we have the console semaphore held. It's
98 * definitely not the perfect debug tool (we don't know if _WE_
99 * hold it are racing, but it helps tracking those weird code
100 * path in the console code where we end up in places I want
101 * locked without the console sempahore held
103 static int console_locked, console_suspended;
106 * If exclusive_console is non-NULL then only this console is to be printed to.
108 static struct console *exclusive_console;
111 * Array of consoles built from command line options (console=)
113 struct console_cmdline
115 char name[16]; /* Name of the driver */
116 int index; /* Minor dev. to use */
117 char *options; /* Options for the driver */
118 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
119 char *brl_options; /* Options for braille driver */
123 #define MAX_CMDLINECONSOLES 8
125 static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
126 static int selected_console = -1;
127 static int preferred_console = -1;
128 int console_set_on_cmdline;
129 EXPORT_SYMBOL(console_set_on_cmdline);
131 /* Flag: console code may call schedule() */
132 static int console_may_schedule;
135 * The printk log buffer consists of a chain of concatenated variable
136 * length records. Every record starts with a record header, containing
137 * the overall length of the record.
139 * The heads to the first and last entry in the buffer, as well as the
140 * sequence numbers of these both entries are maintained when messages
143 * If the heads indicate available messages, the length in the header
144 * tells the start next message. A length == 0 for the next message
145 * indicates a wrap-around to the beginning of the buffer.
147 * Every record carries the monotonic timestamp in microseconds, as well as
148 * the standard userspace syslog level and syslog facility. The usual
149 * kernel messages use LOG_KERN; userspace-injected messages always carry
150 * a matching syslog facility, by default LOG_USER. The origin of every
151 * message can be reliably determined that way.
153 * The human readable log message directly follows the message header. The
154 * length of the message text is stored in the header, the stored message
157 * Optionally, a message can carry a dictionary of properties (key/value pairs),
158 * to provide userspace with a machine-readable message context.
160 * Examples for well-defined, commonly used property names are:
161 * DEVICE=b12:8 device identifier
165 * +sound:card0 subsystem:devname
166 * SUBSYSTEM=pci driver-core subsystem name
168 * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
169 * follows directly after a '=' character. Every property is terminated by
170 * a '\0' character. The last property is not terminated.
172 * Example of a message structure:
173 * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec
174 * 0008 34 00 record is 52 bytes long
175 * 000a 0b 00 text is 11 bytes long
176 * 000c 1f 00 dictionary is 23 bytes long
177 * 000e 03 00 LOG_KERN (facility) LOG_ERR (level)
178 * 0010 69 74 27 73 20 61 20 6c "it's a l"
180 * 001b 44 45 56 49 43 "DEVIC"
181 * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D"
182 * 52 49 56 45 52 3d 62 75 "RIVER=bu"
184 * 0032 00 00 00 padding to next message header
186 * The 'struct log' buffer header must never be directly exported to
187 * userspace, it is a kernel-private implementation detail that might
188 * need to be changed in the future, when the requirements change.
190 * /dev/kmsg exports the structured data in the following line format:
191 * "level,sequnum,timestamp;<message text>\n"
193 * The optional key/value pairs are attached as continuation lines starting
194 * with a space character and terminated by a newline. All possible
195 * non-prinatable characters are escaped in the "\xff" notation.
197 * Users of the export format should ignore possible additional values
198 * separated by ',', and find the message after the ';' character.
202 LOG_NOCONS = 1, /* already flushed, do not print to console */
203 LOG_NEWLINE = 2, /* text ended with a newline */
204 LOG_PREFIX = 4, /* text started with a prefix */
205 LOG_CONT = 8, /* text is a fragment of a continuation line */
209 u64 ts_nsec; /* timestamp in nanoseconds */
210 u16 len; /* length of entire record */
211 u16 text_len; /* length of text buffer */
212 u16 dict_len; /* length of dictionary buffer */
213 u8 facility; /* syslog facility */
214 u8 flags:5; /* internal record flags */
215 u8 level:3; /* syslog level */
219 * The logbuf_lock protects kmsg buffer, indices, counters. It is also
220 * used in interesting ways to provide interlocking in console_unlock();
222 static DEFINE_RAW_SPINLOCK(logbuf_lock);
225 DECLARE_WAIT_QUEUE_HEAD(log_wait);
226 /* the next printk record to read by syslog(READ) or /proc/kmsg */
227 static u64 syslog_seq;
228 static u32 syslog_idx;
229 static enum log_flags syslog_prev;
230 static size_t syslog_partial;
232 /* index and sequence number of the first record stored in the buffer */
233 static u64 log_first_seq;
234 static u32 log_first_idx;
236 /* index and sequence number of the next record to store in the buffer */
237 static u64 log_next_seq;
238 static u32 log_next_idx;
240 /* the next printk record to write to the console */
241 static u64 console_seq;
242 static u32 console_idx;
243 static enum log_flags console_prev;
245 /* the next printk record to read after the last 'clear' command */
246 static u64 clear_seq;
247 static u32 clear_idx;
249 #define PREFIX_MAX 32
250 #define LOG_LINE_MAX 1024 - PREFIX_MAX
253 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
256 #define LOG_ALIGN __alignof__(struct log)
258 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
259 static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
260 static char *log_buf = __log_buf;
261 static u32 log_buf_len = __LOG_BUF_LEN;
263 /* cpu currently holding logbuf_lock */
264 static volatile unsigned int logbuf_cpu = UINT_MAX;
266 /* human readable text of the record */
267 static char *log_text(const struct log *msg)
269 return (char *)msg + sizeof(struct log);
272 /* optional key/value pair dictionary attached to the record */
273 static char *log_dict(const struct log *msg)
275 return (char *)msg + sizeof(struct log) + msg->text_len;
278 /* get record by index; idx must point to valid msg */
279 static struct log *log_from_idx(u32 idx)
281 struct log *msg = (struct log *)(log_buf + idx);
284 * A length == 0 record is the end of buffer marker. Wrap around and
285 * read the message at the start of the buffer.
288 return (struct log *)log_buf;
292 /* get next record; idx must point to valid msg */
293 static u32 log_next(u32 idx)
295 struct log *msg = (struct log *)(log_buf + idx);
297 /* length == 0 indicates the end of the buffer; wrap */
299 * A length == 0 record is the end of buffer marker. Wrap around and
300 * read the message at the start of the buffer as *this* one, and
301 * return the one after that.
304 msg = (struct log *)log_buf;
307 return idx + msg->len;
310 /* insert record into the buffer, discard old ones, update heads */
311 static void log_store(int facility, int level,
312 enum log_flags flags, u64 ts_nsec,
313 const char *dict, u16 dict_len,
314 const char *text, u16 text_len)
319 /* number of '\0' padding bytes to next message */
320 size = sizeof(struct log) + text_len + dict_len;
321 pad_len = (-size) & (LOG_ALIGN - 1);
324 while (log_first_seq < log_next_seq) {
327 if (log_next_idx > log_first_idx)
328 free = max(log_buf_len - log_next_idx, log_first_idx);
330 free = log_first_idx - log_next_idx;
332 if (free > size + sizeof(struct log))
335 /* drop old messages until we have enough contiuous space */
336 log_first_idx = log_next(log_first_idx);
340 if (log_next_idx + size + sizeof(struct log) >= log_buf_len) {
342 * This message + an additional empty header does not fit
343 * at the end of the buffer. Add an empty header with len == 0
344 * to signify a wrap around.
346 memset(log_buf + log_next_idx, 0, sizeof(struct log));
351 msg = (struct log *)(log_buf + log_next_idx);
352 memcpy(log_text(msg), text, text_len);
353 msg->text_len = text_len;
354 memcpy(log_dict(msg), dict, dict_len);
355 msg->dict_len = dict_len;
356 msg->facility = facility;
357 msg->level = level & 7;
358 msg->flags = flags & 0x1f;
360 msg->ts_nsec = ts_nsec;
362 msg->ts_nsec = local_clock();
363 memset(log_dict(msg) + dict_len, 0, pad_len);
364 msg->len = sizeof(struct log) + text_len + dict_len + pad_len;
367 log_next_idx += msg->len;
371 #ifdef CONFIG_SECURITY_DMESG_RESTRICT
372 int dmesg_restrict = 1;
377 static int syslog_action_restricted(int type)
382 * Unless restricted, we allow "read all" and "get buffer size"
385 return type != SYSLOG_ACTION_READ_ALL &&
386 type != SYSLOG_ACTION_SIZE_BUFFER;
389 static int check_syslog_permissions(int type, bool from_file)
392 * If this is from /proc/kmsg and we've already opened it, then we've
393 * already done the capabilities checks at open time.
395 if (from_file && type != SYSLOG_ACTION_OPEN)
398 if (syslog_action_restricted(type)) {
399 if (capable(CAP_SYSLOG))
402 * For historical reasons, accept CAP_SYS_ADMIN too, with
405 if (capable(CAP_SYS_ADMIN)) {
406 pr_warn_once("%s (%d): Attempt to access syslog with "
407 "CAP_SYS_ADMIN but no CAP_SYSLOG "
409 current->comm, task_pid_nr(current));
414 return security_syslog(type);
418 /* /dev/kmsg - userspace message inject/listen interface */
419 struct devkmsg_user {
427 static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
428 unsigned long count, loff_t pos)
432 int level = default_devkmsg_loglevel;
433 int facility = 1; /* LOG_USER */
434 size_t len = iov_length(iv, count);
437 if (len > LOG_LINE_MAX)
439 buf = kmalloc(len+1, GFP_KERNEL);
444 for (i = 0; i < count; i++) {
445 if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) {
449 line += iv[i].iov_len;
453 * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
454 * the decimal value represents 32bit, the lower 3 bit are the log
455 * level, the rest are the log facility.
457 * If no prefix or no userspace facility is specified, we
458 * enforce LOG_USER, to be able to reliably distinguish
459 * kernel-generated messages from userspace-injected ones.
462 if (line[0] == '<') {
465 i = simple_strtoul(line+1, &endp, 10);
466 if (endp && endp[0] == '>') {
477 printk_emit(facility, level, NULL, 0, "%s", line);
483 static ssize_t devkmsg_read(struct file *file, char __user *buf,
484 size_t count, loff_t *ppos)
486 struct devkmsg_user *user = file->private_data;
497 ret = mutex_lock_interruptible(&user->lock);
500 raw_spin_lock_irq(&logbuf_lock);
501 while (user->seq == log_next_seq) {
502 if (file->f_flags & O_NONBLOCK) {
504 raw_spin_unlock_irq(&logbuf_lock);
508 raw_spin_unlock_irq(&logbuf_lock);
509 ret = wait_event_interruptible(log_wait,
510 user->seq != log_next_seq);
513 raw_spin_lock_irq(&logbuf_lock);
516 if (user->seq < log_first_seq) {
517 /* our last seen message is gone, return error and reset */
518 user->idx = log_first_idx;
519 user->seq = log_first_seq;
521 raw_spin_unlock_irq(&logbuf_lock);
525 msg = log_from_idx(user->idx);
526 ts_usec = msg->ts_nsec;
527 do_div(ts_usec, 1000);
530 * If we couldn't merge continuation line fragments during the print,
531 * export the stored flags to allow an optional external merge of the
532 * records. Merging the records isn't always neccessarily correct, like
533 * when we hit a race during printing. In most cases though, it produces
534 * better readable output. 'c' in the record flags mark the first
535 * fragment of a line, '+' the following.
537 if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT))
539 else if ((msg->flags & LOG_CONT) ||
540 ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
543 len = sprintf(user->buf, "%u,%llu,%llu,%c;",
544 (msg->facility << 3) | msg->level,
545 user->seq, ts_usec, cont);
546 user->prev = msg->flags;
548 /* escape non-printable characters */
549 for (i = 0; i < msg->text_len; i++) {
550 unsigned char c = log_text(msg)[i];
552 if (c < ' ' || c >= 127 || c == '\\')
553 len += sprintf(user->buf + len, "\\x%02x", c);
555 user->buf[len++] = c;
557 user->buf[len++] = '\n';
562 for (i = 0; i < msg->dict_len; i++) {
563 unsigned char c = log_dict(msg)[i];
566 user->buf[len++] = ' ';
571 user->buf[len++] = '\n';
576 if (c < ' ' || c >= 127 || c == '\\') {
577 len += sprintf(user->buf + len, "\\x%02x", c);
581 user->buf[len++] = c;
583 user->buf[len++] = '\n';
586 user->idx = log_next(user->idx);
588 raw_spin_unlock_irq(&logbuf_lock);
595 if (copy_to_user(buf, user->buf, len)) {
601 mutex_unlock(&user->lock);
605 static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
607 struct devkmsg_user *user = file->private_data;
615 raw_spin_lock_irq(&logbuf_lock);
618 /* the first record */
619 user->idx = log_first_idx;
620 user->seq = log_first_seq;
624 * The first record after the last SYSLOG_ACTION_CLEAR,
625 * like issued by 'dmesg -c'. Reading /dev/kmsg itself
626 * changes no global state, and does not clear anything.
628 user->idx = clear_idx;
629 user->seq = clear_seq;
632 /* after the last record */
633 user->idx = log_next_idx;
634 user->seq = log_next_seq;
639 raw_spin_unlock_irq(&logbuf_lock);
643 static unsigned int devkmsg_poll(struct file *file, poll_table *wait)
645 struct devkmsg_user *user = file->private_data;
649 return POLLERR|POLLNVAL;
651 poll_wait(file, &log_wait, wait);
653 raw_spin_lock_irq(&logbuf_lock);
654 if (user->seq < log_next_seq) {
655 /* return error when data has vanished underneath us */
656 if (user->seq < log_first_seq)
657 ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI;
659 ret = POLLIN|POLLRDNORM;
661 raw_spin_unlock_irq(&logbuf_lock);
666 static int devkmsg_open(struct inode *inode, struct file *file)
668 struct devkmsg_user *user;
671 /* write-only does not need any file context */
672 if ((file->f_flags & O_ACCMODE) == O_WRONLY)
675 err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
680 user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL);
684 mutex_init(&user->lock);
686 raw_spin_lock_irq(&logbuf_lock);
687 user->idx = log_first_idx;
688 user->seq = log_first_seq;
689 raw_spin_unlock_irq(&logbuf_lock);
691 file->private_data = user;
695 static int devkmsg_release(struct inode *inode, struct file *file)
697 struct devkmsg_user *user = file->private_data;
702 mutex_destroy(&user->lock);
707 const struct file_operations kmsg_fops = {
708 .open = devkmsg_open,
709 .read = devkmsg_read,
710 .aio_write = devkmsg_writev,
711 .llseek = devkmsg_llseek,
712 .poll = devkmsg_poll,
713 .release = devkmsg_release,
718 * This appends the listed symbols to /proc/vmcoreinfo
720 * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
721 * obtain access to symbols that are otherwise very difficult to locate. These
722 * symbols are specifically used so that utilities can access and extract the
723 * dmesg log from a vmcore file after a crash.
725 void log_buf_kexec_setup(void)
727 VMCOREINFO_SYMBOL(log_buf);
728 VMCOREINFO_SYMBOL(log_buf_len);
729 VMCOREINFO_SYMBOL(log_first_idx);
730 VMCOREINFO_SYMBOL(log_next_idx);
732 * Export struct log size and field offsets. User space tools can
733 * parse it and detect any changes to structure down the line.
735 VMCOREINFO_STRUCT_SIZE(log);
736 VMCOREINFO_OFFSET(log, ts_nsec);
737 VMCOREINFO_OFFSET(log, len);
738 VMCOREINFO_OFFSET(log, text_len);
739 VMCOREINFO_OFFSET(log, dict_len);
743 /* requested log_buf_len from kernel cmdline */
744 static unsigned long __initdata new_log_buf_len;
746 /* save requested log_buf_len since it's too early to process it */
747 static int __init log_buf_len_setup(char *str)
749 unsigned size = memparse(str, &str);
752 size = roundup_pow_of_two(size);
753 if (size > log_buf_len)
754 new_log_buf_len = size;
758 early_param("log_buf_len", log_buf_len_setup);
760 void __init setup_log_buf(int early)
766 if (!new_log_buf_len)
772 mem = memblock_alloc(new_log_buf_len, PAGE_SIZE);
775 new_log_buf = __va(mem);
777 new_log_buf = alloc_bootmem_nopanic(new_log_buf_len);
780 if (unlikely(!new_log_buf)) {
781 pr_err("log_buf_len: %ld bytes not available\n",
786 raw_spin_lock_irqsave(&logbuf_lock, flags);
787 log_buf_len = new_log_buf_len;
788 log_buf = new_log_buf;
790 free = __LOG_BUF_LEN - log_next_idx;
791 memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
792 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
794 pr_info("log_buf_len: %d\n", log_buf_len);
795 pr_info("early log buf free: %d(%d%%)\n",
796 free, (free * 100) / __LOG_BUF_LEN);
799 static bool __read_mostly ignore_loglevel;
801 static int __init ignore_loglevel_setup(char *str)
804 printk(KERN_INFO "debug: ignoring loglevel setting.\n");
809 early_param("ignore_loglevel", ignore_loglevel_setup);
810 module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR);
811 MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to"
812 "print all kernel messages to the console.");
814 #ifdef CONFIG_BOOT_PRINTK_DELAY
816 static int boot_delay; /* msecs delay after each printk during bootup */
817 static unsigned long long loops_per_msec; /* based on boot_delay */
819 static int __init boot_delay_setup(char *str)
823 lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */
824 loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
826 get_option(&str, &boot_delay);
827 if (boot_delay > 10 * 1000)
830 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
831 "HZ: %d, loops_per_msec: %llu\n",
832 boot_delay, preset_lpj, lpj, HZ, loops_per_msec);
835 __setup("boot_delay=", boot_delay_setup);
837 static void boot_delay_msec(int level)
839 unsigned long long k;
840 unsigned long timeout;
842 if ((boot_delay == 0 || system_state != SYSTEM_BOOTING)
843 || (level >= console_loglevel && !ignore_loglevel)) {
847 k = (unsigned long long)loops_per_msec * boot_delay;
849 timeout = jiffies + msecs_to_jiffies(boot_delay);
854 * use (volatile) jiffies to prevent
855 * compiler reduction; loop termination via jiffies
856 * is secondary and may or may not happen.
858 if (time_after(jiffies, timeout))
860 touch_nmi_watchdog();
864 static inline void boot_delay_msec(int level)
869 #if defined(CONFIG_PRINTK_TIME)
870 static bool printk_time = 1;
872 static bool printk_time;
874 module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
876 static size_t print_time(u64 ts, char *buf)
878 unsigned long rem_nsec;
883 rem_nsec = do_div(ts, 1000000000);
886 return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts);
888 return sprintf(buf, "[%5lu.%06lu] ",
889 (unsigned long)ts, rem_nsec / 1000);
892 static size_t print_prefix(const struct log *msg, bool syslog, char *buf)
895 unsigned int prefix = (msg->facility << 3) | msg->level;
899 len += sprintf(buf, "<%u>", prefix);
904 else if (prefix > 99)
911 len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
915 static size_t msg_print_text(const struct log *msg, enum log_flags prev,
916 bool syslog, char *buf, size_t size)
918 const char *text = log_text(msg);
919 size_t text_size = msg->text_len;
924 if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
927 if (msg->flags & LOG_CONT) {
928 if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE))
931 if (!(msg->flags & LOG_NEWLINE))
936 const char *next = memchr(text, '\n', text_size);
940 text_len = next - text;
942 text_size -= next - text;
944 text_len = text_size;
948 if (print_prefix(msg, syslog, NULL) +
949 text_len + 1 >= size - len)
953 len += print_prefix(msg, syslog, buf + len);
954 memcpy(buf + len, text, text_len);
959 /* SYSLOG_ACTION_* buffer size only calculation */
961 len += print_prefix(msg, syslog, NULL);
974 static int syslog_print(char __user *buf, int size)
980 text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
988 raw_spin_lock_irq(&logbuf_lock);
989 if (syslog_seq < log_first_seq) {
990 /* messages are gone, move to first one */
991 syslog_seq = log_first_seq;
992 syslog_idx = log_first_idx;
996 if (syslog_seq == log_next_seq) {
997 raw_spin_unlock_irq(&logbuf_lock);
1001 skip = syslog_partial;
1002 msg = log_from_idx(syslog_idx);
1003 n = msg_print_text(msg, syslog_prev, true, text,
1004 LOG_LINE_MAX + PREFIX_MAX);
1005 if (n - syslog_partial <= size) {
1006 /* message fits into buffer, move forward */
1007 syslog_idx = log_next(syslog_idx);
1009 syslog_prev = msg->flags;
1010 n -= syslog_partial;
1013 /* partial read(), remember position */
1015 syslog_partial += n;
1018 raw_spin_unlock_irq(&logbuf_lock);
1023 if (copy_to_user(buf, text + skip, n)) {
1038 static int syslog_print_all(char __user *buf, int size, bool clear)
1043 text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
1047 raw_spin_lock_irq(&logbuf_lock);
1052 enum log_flags prev;
1054 if (clear_seq < log_first_seq) {
1055 /* messages are gone, move to first available one */
1056 clear_seq = log_first_seq;
1057 clear_idx = log_first_idx;
1061 * Find first record that fits, including all following records,
1062 * into the user-provided buffer for this dump.
1067 while (seq < log_next_seq) {
1068 struct log *msg = log_from_idx(idx);
1070 len += msg_print_text(msg, prev, true, NULL, 0);
1072 idx = log_next(idx);
1076 /* move first record forward until length fits into the buffer */
1080 while (len > size && seq < log_next_seq) {
1081 struct log *msg = log_from_idx(idx);
1083 len -= msg_print_text(msg, prev, true, NULL, 0);
1085 idx = log_next(idx);
1089 /* last message fitting into this dump */
1090 next_seq = log_next_seq;
1094 while (len >= 0 && seq < next_seq) {
1095 struct log *msg = log_from_idx(idx);
1098 textlen = msg_print_text(msg, prev, true, text,
1099 LOG_LINE_MAX + PREFIX_MAX);
1104 idx = log_next(idx);
1108 raw_spin_unlock_irq(&logbuf_lock);
1109 if (copy_to_user(buf + len, text, textlen))
1113 raw_spin_lock_irq(&logbuf_lock);
1115 if (seq < log_first_seq) {
1116 /* messages are gone, move to next one */
1117 seq = log_first_seq;
1118 idx = log_first_idx;
1125 clear_seq = log_next_seq;
1126 clear_idx = log_next_idx;
1128 raw_spin_unlock_irq(&logbuf_lock);
1134 int do_syslog(int type, char __user *buf, int len, bool from_file)
1137 static int saved_console_loglevel = -1;
1140 error = check_syslog_permissions(type, from_file);
1144 error = security_syslog(type);
1149 case SYSLOG_ACTION_CLOSE: /* Close log */
1151 case SYSLOG_ACTION_OPEN: /* Open log */
1153 case SYSLOG_ACTION_READ: /* Read from log */
1155 if (!buf || len < 0)
1160 if (!access_ok(VERIFY_WRITE, buf, len)) {
1164 error = wait_event_interruptible(log_wait,
1165 syslog_seq != log_next_seq);
1168 error = syslog_print(buf, len);
1170 /* Read/clear last kernel messages */
1171 case SYSLOG_ACTION_READ_CLEAR:
1174 /* Read last kernel messages */
1175 case SYSLOG_ACTION_READ_ALL:
1177 if (!buf || len < 0)
1182 if (!access_ok(VERIFY_WRITE, buf, len)) {
1186 error = syslog_print_all(buf, len, clear);
1188 /* Clear ring buffer */
1189 case SYSLOG_ACTION_CLEAR:
1190 syslog_print_all(NULL, 0, true);
1192 /* Disable logging to console */
1193 case SYSLOG_ACTION_CONSOLE_OFF:
1194 if (saved_console_loglevel == -1)
1195 saved_console_loglevel = console_loglevel;
1196 console_loglevel = minimum_console_loglevel;
1198 /* Enable logging to console */
1199 case SYSLOG_ACTION_CONSOLE_ON:
1200 if (saved_console_loglevel != -1) {
1201 console_loglevel = saved_console_loglevel;
1202 saved_console_loglevel = -1;
1205 /* Set level of messages printed to console */
1206 case SYSLOG_ACTION_CONSOLE_LEVEL:
1208 if (len < 1 || len > 8)
1210 if (len < minimum_console_loglevel)
1211 len = minimum_console_loglevel;
1212 console_loglevel = len;
1213 /* Implicitly re-enable logging to console */
1214 saved_console_loglevel = -1;
1217 /* Number of chars in the log buffer */
1218 case SYSLOG_ACTION_SIZE_UNREAD:
1219 raw_spin_lock_irq(&logbuf_lock);
1220 if (syslog_seq < log_first_seq) {
1221 /* messages are gone, move to first one */
1222 syslog_seq = log_first_seq;
1223 syslog_idx = log_first_idx;
1229 * Short-cut for poll(/"proc/kmsg") which simply checks
1230 * for pending data, not the size; return the count of
1231 * records, not the length.
1233 error = log_next_idx - syslog_idx;
1235 u64 seq = syslog_seq;
1236 u32 idx = syslog_idx;
1237 enum log_flags prev = syslog_prev;
1240 while (seq < log_next_seq) {
1241 struct log *msg = log_from_idx(idx);
1243 error += msg_print_text(msg, prev, true, NULL, 0);
1244 idx = log_next(idx);
1248 error -= syslog_partial;
1250 raw_spin_unlock_irq(&logbuf_lock);
1252 /* Size of the log buffer */
1253 case SYSLOG_ACTION_SIZE_BUFFER:
1254 error = log_buf_len;
1264 SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
1266 return do_syslog(type, buf, len, SYSLOG_FROM_READER);
1270 * Call the console drivers, asking them to write out
1271 * log_buf[start] to log_buf[end - 1].
1272 * The console_lock must be held.
1274 static void call_console_drivers(int level, const char *text, size_t len)
1276 struct console *con;
1278 trace_console(text, len);
1280 if (level >= console_loglevel && !ignore_loglevel)
1282 if (!console_drivers)
1285 for_each_console(con) {
1286 if (exclusive_console && con != exclusive_console)
1288 if (!(con->flags & CON_ENABLED))
1292 if (!cpu_online(smp_processor_id()) &&
1293 !(con->flags & CON_ANYTIME))
1295 con->write(con, text, len);
1300 * Zap console related locks when oopsing. Only zap at most once
1301 * every 10 seconds, to leave time for slow consoles to print a
1304 static void zap_locks(void)
1306 static unsigned long oops_timestamp;
1308 if (time_after_eq(jiffies, oops_timestamp) &&
1309 !time_after(jiffies, oops_timestamp + 30 * HZ))
1312 oops_timestamp = jiffies;
1315 /* If a crash is occurring, make sure we can't deadlock */
1316 raw_spin_lock_init(&logbuf_lock);
1317 /* And make sure that we print immediately */
1318 sema_init(&console_sem, 1);
1321 /* Check if we have any console registered that can be called early in boot. */
1322 static int have_callable_console(void)
1324 struct console *con;
1326 for_each_console(con)
1327 if (con->flags & CON_ANYTIME)
1333 bool console_enabled = 1;
1336 * Can we actually use the console at this time on this cpu?
1338 * Console drivers may assume that per-cpu resources have
1339 * been allocated. So unless they're explicitly marked as
1340 * being able to cope (CON_ANYTIME) don't call them until
1341 * this CPU is officially up.
1343 static inline int can_use_console(unsigned int cpu)
1345 return console_enabled && (cpu_online(cpu) || have_callable_console());
1349 * Try to get console ownership to actually show the kernel
1350 * messages from a 'printk'. Return true (and with the
1351 * console_lock held, and 'console_locked' set) if it
1352 * is successful, false otherwise.
1354 * This gets called with the 'logbuf_lock' spinlock held and
1355 * interrupts disabled. It should return with 'lockbuf_lock'
1356 * released but interrupts still disabled.
1358 static int console_trylock_for_printk(unsigned int cpu)
1359 __releases(&logbuf_lock)
1361 int retval = 0, wake = 0;
1363 if (console_trylock()) {
1367 * If we can't use the console, we need to release
1368 * the console semaphore by hand to avoid flushing
1369 * the buffer. We need to hold the console semaphore
1370 * in order to do this test safely.
1372 if (!can_use_console(cpu)) {
1378 logbuf_cpu = UINT_MAX;
1379 raw_spin_unlock(&logbuf_lock);
1385 int printk_delay_msec __read_mostly;
1387 static inline void printk_delay(void)
1389 if (unlikely(printk_delay_msec)) {
1390 int m = printk_delay_msec;
1394 touch_nmi_watchdog();
1400 * Continuation lines are buffered, and not committed to the record buffer
1401 * until the line is complete, or a race forces it. The line fragments
1402 * though, are printed immediately to the consoles to ensure everything has
1403 * reached the console in case of a kernel crash.
1405 static struct cont {
1406 char buf[LOG_LINE_MAX];
1407 size_t len; /* length == 0 means unused buffer */
1408 size_t cons; /* bytes written to console */
1409 struct task_struct *owner; /* task of first print*/
1410 u64 ts_nsec; /* time of first print */
1411 u8 level; /* log level of first message */
1412 u8 facility; /* log level of first message */
1413 enum log_flags flags; /* prefix, newline flags */
1414 bool flushed:1; /* buffer sealed and committed */
1417 static void cont_flush(enum log_flags flags)
1426 * If a fragment of this line was directly flushed to the
1427 * console; wait for the console to pick up the rest of the
1428 * line. LOG_NOCONS suppresses a duplicated output.
1430 log_store(cont.facility, cont.level, flags | LOG_NOCONS,
1431 cont.ts_nsec, NULL, 0, cont.buf, cont.len);
1433 cont.flushed = true;
1436 * If no fragment of this line ever reached the console,
1437 * just submit it to the store and free the buffer.
1439 log_store(cont.facility, cont.level, flags, 0,
1440 NULL, 0, cont.buf, cont.len);
1445 static bool cont_add(int facility, int level, const char *text, size_t len)
1447 if (cont.len && cont.flushed)
1450 if (cont.len + len > sizeof(cont.buf)) {
1451 /* the line gets too long, split it up in separate records */
1452 cont_flush(LOG_CONT);
1457 cont.facility = facility;
1459 cont.owner = current;
1460 cont.ts_nsec = local_clock();
1463 cont.flushed = false;
1466 memcpy(cont.buf + cont.len, text, len);
1469 if (cont.len > (sizeof(cont.buf) * 80) / 100)
1470 cont_flush(LOG_CONT);
1475 static size_t cont_print_text(char *text, size_t size)
1480 if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) {
1481 textlen += print_time(cont.ts_nsec, text);
1485 len = cont.len - cont.cons;
1489 memcpy(text + textlen, cont.buf + cont.cons, len);
1491 cont.cons = cont.len;
1495 if (cont.flags & LOG_NEWLINE)
1496 text[textlen++] = '\n';
1497 /* got everything, release buffer */
1503 asmlinkage int vprintk_emit(int facility, int level,
1504 const char *dict, size_t dictlen,
1505 const char *fmt, va_list args)
1507 static int recursion_bug;
1508 static char textbuf[LOG_LINE_MAX];
1509 char *text = textbuf;
1511 enum log_flags lflags = 0;
1512 unsigned long flags;
1514 int printed_len = 0;
1516 boot_delay_msec(level);
1519 /* This stops the holder of console_sem just where we want him */
1520 local_irq_save(flags);
1521 this_cpu = smp_processor_id();
1524 * Ouch, printk recursed into itself!
1526 if (unlikely(logbuf_cpu == this_cpu)) {
1528 * If a crash is occurring during printk() on this CPU,
1529 * then try to get the crash message out but make sure
1530 * we can't deadlock. Otherwise just return to avoid the
1531 * recursion and return - but flag the recursion so that
1532 * it can be printed at the next appropriate moment:
1534 if (!oops_in_progress && !lockdep_recursing(current)) {
1536 goto out_restore_irqs;
1542 raw_spin_lock(&logbuf_lock);
1543 logbuf_cpu = this_cpu;
1545 if (recursion_bug) {
1546 static const char recursion_msg[] =
1547 "BUG: recent printk recursion!";
1550 printed_len += strlen(recursion_msg);
1551 /* emit KERN_CRIT message */
1552 log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
1553 NULL, 0, recursion_msg, printed_len);
1557 * The printf needs to come first; we need the syslog
1558 * prefix which might be passed-in as a parameter.
1560 text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
1562 /* mark and strip a trailing newline */
1563 if (text_len && text[text_len-1] == '\n') {
1565 lflags |= LOG_NEWLINE;
1568 /* strip kernel syslog prefix and extract log level or control flags */
1569 if (facility == 0) {
1570 int kern_level = printk_get_level(text);
1573 const char *end_of_header = printk_skip_level(text);
1574 switch (kern_level) {
1577 level = kern_level - '0';
1578 case 'd': /* KERN_DEFAULT */
1579 lflags |= LOG_PREFIX;
1580 case 'c': /* KERN_CONT */
1583 text_len -= end_of_header - text;
1584 text = (char *)end_of_header;
1588 #ifdef CONFIG_EARLY_PRINTK_DIRECT
1593 level = default_message_loglevel;
1596 lflags |= LOG_PREFIX|LOG_NEWLINE;
1598 if (!(lflags & LOG_NEWLINE)) {
1600 * Flush the conflicting buffer. An earlier newline was missing,
1601 * or another task also prints continuation lines.
1603 if (cont.len && (lflags & LOG_PREFIX || cont.owner != current))
1604 cont_flush(LOG_NEWLINE);
1606 /* buffer line if possible, otherwise store it right away */
1607 if (!cont_add(facility, level, text, text_len))
1608 log_store(facility, level, lflags | LOG_CONT, 0,
1609 dict, dictlen, text, text_len);
1611 bool stored = false;
1614 * If an earlier newline was missing and it was the same task,
1615 * either merge it with the current buffer and flush, or if
1616 * there was a race with interrupts (prefix == true) then just
1617 * flush it out and store this line separately.
1619 if (cont.len && cont.owner == current) {
1620 if (!(lflags & LOG_PREFIX))
1621 stored = cont_add(facility, level, text, text_len);
1622 cont_flush(LOG_NEWLINE);
1626 log_store(facility, level, lflags, 0,
1627 dict, dictlen, text, text_len);
1629 printed_len += text_len;
1632 * Try to acquire and then immediately release the console semaphore.
1633 * The release will print out buffers and wake up /dev/kmsg and syslog()
1636 * The console_trylock_for_printk() function will release 'logbuf_lock'
1637 * regardless of whether it actually gets the console semaphore or not.
1639 if (console_trylock_for_printk(this_cpu))
1644 local_irq_restore(flags);
1648 EXPORT_SYMBOL(vprintk_emit);
1650 asmlinkage int vprintk(const char *fmt, va_list args)
1652 return vprintk_emit(0, -1, NULL, 0, fmt, args);
1654 EXPORT_SYMBOL(vprintk);
1656 asmlinkage int printk_emit(int facility, int level,
1657 const char *dict, size_t dictlen,
1658 const char *fmt, ...)
1663 va_start(args, fmt);
1664 r = vprintk_emit(facility, level, dict, dictlen, fmt, args);
1669 EXPORT_SYMBOL(printk_emit);
1672 * printk - print a kernel message
1673 * @fmt: format string
1675 * This is printk(). It can be called from any context. We want it to work.
1677 * We try to grab the console_lock. If we succeed, it's easy - we log the
1678 * output and call the console drivers. If we fail to get the semaphore, we
1679 * place the output into the log buffer and return. The current holder of
1680 * the console_sem will notice the new output in console_unlock(); and will
1681 * send it to the consoles before releasing the lock.
1683 * One effect of this deferred printing is that code which calls printk() and
1684 * then changes console_loglevel may break. This is because console_loglevel
1685 * is inspected when the actual printing occurs.
1690 * See the vsnprintf() documentation for format string extensions over C99.
1692 asmlinkage int printk(const char *fmt, ...)
1697 #ifdef CONFIG_KGDB_KDB
1698 if (unlikely(kdb_trap_printk)) {
1699 va_start(args, fmt);
1700 r = vkdb_printf(fmt, args);
1705 va_start(args, fmt);
1706 r = vprintk_emit(0, -1, NULL, 0, fmt, args);
1711 EXPORT_SYMBOL(printk);
1713 #else /* CONFIG_PRINTK */
1715 #define LOG_LINE_MAX 0
1716 #define PREFIX_MAX 0
1717 #define LOG_LINE_MAX 0
1718 static u64 syslog_seq;
1719 static u32 syslog_idx;
1720 static u64 console_seq;
1721 static u32 console_idx;
1722 static enum log_flags syslog_prev;
1723 static u64 log_first_seq;
1724 static u32 log_first_idx;
1725 static u64 log_next_seq;
1726 static enum log_flags console_prev;
1727 static struct cont {
1733 static struct log *log_from_idx(u32 idx) { return NULL; }
1734 static u32 log_next(u32 idx) { return 0; }
1735 static void call_console_drivers(int level, const char *text, size_t len) {}
1736 static size_t msg_print_text(const struct log *msg, enum log_flags prev,
1737 bool syslog, char *buf, size_t size) { return 0; }
1738 static size_t cont_print_text(char *text, size_t size) { return 0; }
1740 #endif /* CONFIG_PRINTK */
1742 #ifdef CONFIG_EARLY_PRINTK
1743 struct console *early_console;
1745 void early_vprintk(const char *fmt, va_list ap)
1747 if (early_console) {
1749 int n = vscnprintf(buf, sizeof(buf), fmt, ap);
1751 early_console->write(early_console, buf, n);
1755 asmlinkage void early_printk(const char *fmt, ...)
1760 early_vprintk(fmt, ap);
1765 static int __add_preferred_console(char *name, int idx, char *options,
1768 struct console_cmdline *c;
1772 * See if this tty is not yet registered, and
1773 * if we have a slot free.
1775 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
1776 if (strcmp(console_cmdline[i].name, name) == 0 &&
1777 console_cmdline[i].index == idx) {
1779 selected_console = i;
1782 if (i == MAX_CMDLINECONSOLES)
1785 selected_console = i;
1786 c = &console_cmdline[i];
1787 strlcpy(c->name, name, sizeof(c->name));
1788 c->options = options;
1789 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1790 c->brl_options = brl_options;
1796 * Set up a list of consoles. Called from init/main.c
1798 static int __init console_setup(char *str)
1800 char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
1801 char *s, *options, *brl_options = NULL;
1804 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1805 if (!memcmp(str, "brl,", 4)) {
1808 } else if (!memcmp(str, "brl=", 4)) {
1809 brl_options = str + 4;
1810 str = strchr(brl_options, ',');
1812 printk(KERN_ERR "need port name after brl=\n");
1820 * Decode str into name, index, options.
1822 if (str[0] >= '0' && str[0] <= '9') {
1823 strcpy(buf, "ttyS");
1824 strncpy(buf + 4, str, sizeof(buf) - 5);
1826 strncpy(buf, str, sizeof(buf) - 1);
1828 buf[sizeof(buf) - 1] = 0;
1829 if ((options = strchr(str, ',')) != NULL)
1832 if (!strcmp(str, "ttya"))
1833 strcpy(buf, "ttyS0");
1834 if (!strcmp(str, "ttyb"))
1835 strcpy(buf, "ttyS1");
1837 for (s = buf; *s; s++)
1838 if ((*s >= '0' && *s <= '9') || *s == ',')
1840 idx = simple_strtoul(s, NULL, 10);
1843 __add_preferred_console(buf, idx, options, brl_options);
1844 console_set_on_cmdline = 1;
1847 __setup("console=", console_setup);
1850 * add_preferred_console - add a device to the list of preferred consoles.
1851 * @name: device name
1852 * @idx: device index
1853 * @options: options for this console
1855 * The last preferred console added will be used for kernel messages
1856 * and stdin/out/err for init. Normally this is used by console_setup
1857 * above to handle user-supplied console arguments; however it can also
1858 * be used by arch-specific code either to override the user or more
1859 * commonly to provide a default console (ie from PROM variables) when
1860 * the user has not supplied one.
1862 int add_preferred_console(char *name, int idx, char *options)
1864 return __add_preferred_console(name, idx, options, NULL);
1867 int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
1869 struct console_cmdline *c;
1872 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
1873 if (strcmp(console_cmdline[i].name, name) == 0 &&
1874 console_cmdline[i].index == idx) {
1875 c = &console_cmdline[i];
1876 strlcpy(c->name, name_new, sizeof(c->name));
1877 c->name[sizeof(c->name) - 1] = 0;
1878 c->options = options;
1886 bool console_suspend_enabled = 1;
1887 EXPORT_SYMBOL(console_suspend_enabled);
1889 static int __init console_suspend_disable(char *str)
1891 console_suspend_enabled = 0;
1894 __setup("no_console_suspend", console_suspend_disable);
1895 module_param_named(console_suspend, console_suspend_enabled,
1896 bool, S_IRUGO | S_IWUSR);
1897 MODULE_PARM_DESC(console_suspend, "suspend console during suspend"
1898 " and hibernate operations");
1901 * suspend_console - suspend the console subsystem
1903 * This disables printk() while we go into suspend states
1905 void suspend_console(void)
1907 if (!console_suspend_enabled)
1909 printk("Suspending console(s) (use no_console_suspend to debug)\n");
1911 console_suspended = 1;
1915 void resume_console(void)
1917 if (!console_suspend_enabled)
1920 console_suspended = 0;
1925 * console_cpu_notify - print deferred console messages after CPU hotplug
1926 * @self: notifier struct
1927 * @action: CPU hotplug event
1930 * If printk() is called from a CPU that is not online yet, the messages
1931 * will be spooled but will not show up on the console. This function is
1932 * called when a new CPU comes online (or fails to come up), and ensures
1933 * that any such output gets printed.
1935 static int __cpuinit console_cpu_notify(struct notifier_block *self,
1936 unsigned long action, void *hcpu)
1941 case CPU_DOWN_FAILED:
1942 case CPU_UP_CANCELED:
1950 * console_lock - lock the console system for exclusive use.
1952 * Acquires a lock which guarantees that the caller has
1953 * exclusive access to the console system and the console_drivers list.
1955 * Can sleep, returns nothing.
1957 void console_lock(void)
1962 if (console_suspended)
1965 console_may_schedule = 1;
1966 mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
1968 EXPORT_SYMBOL(console_lock);
1971 * console_trylock - try to lock the console system for exclusive use.
1973 * Tried to acquire a lock which guarantees that the caller has
1974 * exclusive access to the console system and the console_drivers list.
1976 * returns 1 on success, and 0 on failure to acquire the lock.
1978 int console_trylock(void)
1980 if (down_trylock(&console_sem))
1982 if (console_suspended) {
1987 console_may_schedule = 0;
1988 mutex_acquire(&console_lock_dep_map, 0, 1, _RET_IP_);
1991 EXPORT_SYMBOL(console_trylock);
1993 int is_console_locked(void)
1995 return console_locked;
1998 static void console_cont_flush(char *text, size_t size)
2000 unsigned long flags;
2003 raw_spin_lock_irqsave(&logbuf_lock, flags);
2009 * We still queue earlier records, likely because the console was
2010 * busy. The earlier ones need to be printed before this one, we
2011 * did not flush any fragment so far, so just let it queue up.
2013 if (console_seq < log_next_seq && !cont.cons)
2016 len = cont_print_text(text, size);
2017 raw_spin_unlock(&logbuf_lock);
2018 stop_critical_timings();
2019 call_console_drivers(cont.level, text, len);
2020 start_critical_timings();
2021 local_irq_restore(flags);
2024 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2028 * console_unlock - unlock the console system
2030 * Releases the console_lock which the caller holds on the console system
2031 * and the console driver list.
2033 * While the console_lock was held, console output may have been buffered
2034 * by printk(). If this is the case, console_unlock(); emits
2035 * the output prior to releasing the lock.
2037 * If there is output waiting, we wake /dev/kmsg and syslog() users.
2039 * console_unlock(); may be called from any context.
2041 void console_unlock(void)
2043 static char text[LOG_LINE_MAX + PREFIX_MAX];
2044 static u64 seen_seq;
2045 unsigned long flags;
2046 bool wake_klogd = false;
2049 if (console_suspended) {
2054 console_may_schedule = 0;
2056 /* flush buffered message fragment immediately to console */
2057 console_cont_flush(text, sizeof(text));
2064 raw_spin_lock_irqsave(&logbuf_lock, flags);
2065 if (seen_seq != log_next_seq) {
2067 seen_seq = log_next_seq;
2070 if (console_seq < log_first_seq) {
2071 /* messages are gone, move to first one */
2072 console_seq = log_first_seq;
2073 console_idx = log_first_idx;
2077 if (console_seq == log_next_seq)
2080 msg = log_from_idx(console_idx);
2081 if (msg->flags & LOG_NOCONS) {
2083 * Skip record we have buffered and already printed
2084 * directly to the console when we received it.
2086 console_idx = log_next(console_idx);
2089 * We will get here again when we register a new
2090 * CON_PRINTBUFFER console. Clear the flag so we
2091 * will properly dump everything later.
2093 msg->flags &= ~LOG_NOCONS;
2094 console_prev = msg->flags;
2099 len = msg_print_text(msg, console_prev, false,
2100 text, sizeof(text));
2101 console_idx = log_next(console_idx);
2103 console_prev = msg->flags;
2104 raw_spin_unlock(&logbuf_lock);
2106 stop_critical_timings(); /* don't trace print latency */
2107 call_console_drivers(level, text, len);
2108 start_critical_timings();
2109 local_irq_restore(flags);
2112 mutex_release(&console_lock_dep_map, 1, _RET_IP_);
2114 /* Release the exclusive_console once it is used */
2115 if (unlikely(exclusive_console))
2116 exclusive_console = NULL;
2118 raw_spin_unlock(&logbuf_lock);
2123 * Someone could have filled up the buffer again, so re-check if there's
2124 * something to flush. In case we cannot trylock the console_sem again,
2125 * there's a new owner and the console_unlock() from them will do the
2126 * flush, no worries.
2128 raw_spin_lock(&logbuf_lock);
2129 retry = console_seq != log_next_seq;
2130 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2132 if (retry && console_trylock())
2138 EXPORT_SYMBOL(console_unlock);
2141 * console_conditional_schedule - yield the CPU if required
2143 * If the console code is currently allowed to sleep, and
2144 * if this CPU should yield the CPU to another task, do
2147 * Must be called within console_lock();.
2149 void __sched console_conditional_schedule(void)
2151 if (console_may_schedule)
2154 EXPORT_SYMBOL(console_conditional_schedule);
2156 void console_unblank(void)
2161 * console_unblank can no longer be called in interrupt context unless
2162 * oops_in_progress is set to 1..
2164 if (oops_in_progress) {
2165 if (down_trylock(&console_sem) != 0)
2171 console_may_schedule = 0;
2173 if ((c->flags & CON_ENABLED) && c->unblank)
2179 * Return the console tty driver structure and its associated index
2181 struct tty_driver *console_device(int *index)
2184 struct tty_driver *driver = NULL;
2187 for_each_console(c) {
2190 driver = c->device(c, index);
2199 * Prevent further output on the passed console device so that (for example)
2200 * serial drivers can disable console output before suspending a port, and can
2201 * re-enable output afterwards.
2203 void console_stop(struct console *console)
2206 console->flags &= ~CON_ENABLED;
2209 EXPORT_SYMBOL(console_stop);
2211 void console_start(struct console *console)
2214 console->flags |= CON_ENABLED;
2217 EXPORT_SYMBOL(console_start);
2219 static int __read_mostly keep_bootcon;
2221 static int __init keep_bootcon_setup(char *str)
2224 printk(KERN_INFO "debug: skip boot console de-registration.\n");
2229 early_param("keep_bootcon", keep_bootcon_setup);
2232 * The console driver calls this routine during kernel initialization
2233 * to register the console printing procedure with printk() and to
2234 * print any messages that were printed by the kernel before the
2235 * console driver was initialized.
2237 * This can happen pretty early during the boot process (because of
2238 * early_printk) - sometimes before setup_arch() completes - be careful
2239 * of what kernel features are used - they may not be initialised yet.
2241 * There are two types of consoles - bootconsoles (early_printk) and
2242 * "real" consoles (everything which is not a bootconsole) which are
2243 * handled differently.
2244 * - Any number of bootconsoles can be registered at any time.
2245 * - As soon as a "real" console is registered, all bootconsoles
2246 * will be unregistered automatically.
2247 * - Once a "real" console is registered, any attempt to register a
2248 * bootconsoles will be rejected
2250 void register_console(struct console *newcon)
2253 unsigned long flags;
2254 struct console *bcon = NULL;
2257 * before we register a new CON_BOOT console, make sure we don't
2258 * already have a valid console
2260 if (console_drivers && newcon->flags & CON_BOOT) {
2261 /* find the last or real console */
2262 for_each_console(bcon) {
2263 if (!(bcon->flags & CON_BOOT)) {
2264 printk(KERN_INFO "Too late to register bootconsole %s%d\n",
2265 newcon->name, newcon->index);
2271 if (console_drivers && console_drivers->flags & CON_BOOT)
2272 bcon = console_drivers;
2274 if (preferred_console < 0 || bcon || !console_drivers)
2275 preferred_console = selected_console;
2277 if (newcon->early_setup)
2278 newcon->early_setup();
2281 * See if we want to use this console driver. If we
2282 * didn't select a console we take the first one
2283 * that registers here.
2285 if (preferred_console < 0) {
2286 if (newcon->index < 0)
2288 if (newcon->setup == NULL ||
2289 newcon->setup(newcon, NULL) == 0) {
2290 newcon->flags |= CON_ENABLED;
2291 if (newcon->device) {
2292 newcon->flags |= CON_CONSDEV;
2293 preferred_console = 0;
2299 * See if this console matches one we selected on
2302 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
2304 BUILD_BUG_ON(sizeof(console_cmdline[i].name) !=
2305 sizeof(newcon->name));
2306 if (strcmp(console_cmdline[i].name, newcon->name) != 0)
2308 if (newcon->index >= 0 &&
2309 newcon->index != console_cmdline[i].index)
2311 if (newcon->index < 0)
2312 newcon->index = console_cmdline[i].index;
2313 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
2314 if (console_cmdline[i].brl_options) {
2315 newcon->flags |= CON_BRL;
2316 braille_register_console(newcon,
2317 console_cmdline[i].index,
2318 console_cmdline[i].options,
2319 console_cmdline[i].brl_options);
2323 if (newcon->setup &&
2324 newcon->setup(newcon, console_cmdline[i].options) != 0)
2326 newcon->flags |= CON_ENABLED;
2327 newcon->index = console_cmdline[i].index;
2328 if (i == selected_console) {
2329 newcon->flags |= CON_CONSDEV;
2330 preferred_console = selected_console;
2335 if (!(newcon->flags & CON_ENABLED))
2339 * If we have a bootconsole, and are switching to a real console,
2340 * don't print everything out again, since when the boot console, and
2341 * the real console are the same physical device, it's annoying to
2342 * see the beginning boot messages twice
2344 if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
2345 newcon->flags &= ~CON_PRINTBUFFER;
2348 * Put this console in the list - keep the
2349 * preferred driver at the head of the list.
2352 if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
2353 newcon->next = console_drivers;
2354 console_drivers = newcon;
2356 newcon->next->flags &= ~CON_CONSDEV;
2358 newcon->next = console_drivers->next;
2359 console_drivers->next = newcon;
2361 if (newcon->flags & CON_PRINTBUFFER) {
2363 * console_unlock(); will print out the buffered messages
2366 raw_spin_lock_irqsave(&logbuf_lock, flags);
2367 console_seq = syslog_seq;
2368 console_idx = syslog_idx;
2369 console_prev = syslog_prev;
2370 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2372 * We're about to replay the log buffer. Only do this to the
2373 * just-registered console to avoid excessive message spam to
2374 * the already-registered consoles.
2376 exclusive_console = newcon;
2379 console_sysfs_notify();
2382 * By unregistering the bootconsoles after we enable the real console
2383 * we get the "console xxx enabled" message on all the consoles -
2384 * boot consoles, real consoles, etc - this is to ensure that end
2385 * users know there might be something in the kernel's log buffer that
2386 * went to the bootconsole (that they do not see on the real console)
2389 ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
2391 /* we need to iterate through twice, to make sure we print
2392 * everything out, before we unregister the console(s)
2394 printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n",
2395 newcon->name, newcon->index);
2396 for_each_console(bcon)
2397 if (bcon->flags & CON_BOOT)
2398 unregister_console(bcon);
2400 printk(KERN_INFO "%sconsole [%s%d] enabled\n",
2401 (newcon->flags & CON_BOOT) ? "boot" : "" ,
2402 newcon->name, newcon->index);
2405 EXPORT_SYMBOL(register_console);
2407 int unregister_console(struct console *console)
2409 struct console *a, *b;
2412 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
2413 if (console->flags & CON_BRL)
2414 return braille_unregister_console(console);
2418 if (console_drivers == console) {
2419 console_drivers=console->next;
2421 } else if (console_drivers) {
2422 for (a=console_drivers->next, b=console_drivers ;
2423 a; b=a, a=b->next) {
2433 * If this isn't the last console and it has CON_CONSDEV set, we
2434 * need to set it on the next preferred console.
2436 if (console_drivers != NULL && console->flags & CON_CONSDEV)
2437 console_drivers->flags |= CON_CONSDEV;
2440 console_sysfs_notify();
2443 EXPORT_SYMBOL(unregister_console);
2445 static int __init printk_late_init(void)
2447 struct console *con;
2449 for_each_console(con) {
2450 if (!keep_bootcon && con->flags & CON_BOOT) {
2451 printk(KERN_INFO "turn off boot console %s%d\n",
2452 con->name, con->index);
2453 unregister_console(con);
2456 hotcpu_notifier(console_cpu_notify, 0);
2459 late_initcall(printk_late_init);
2461 #if defined CONFIG_PRINTK
2463 * Delayed printk version, for scheduler-internal messages:
2465 #define PRINTK_BUF_SIZE 512
2467 #define PRINTK_PENDING_WAKEUP 0x01
2468 #define PRINTK_PENDING_SCHED 0x02
2470 static DEFINE_PER_CPU(int, printk_pending);
2471 static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
2473 static void wake_up_klogd_work_func(struct irq_work *irq_work)
2475 int pending = __this_cpu_xchg(printk_pending, 0);
2477 if (pending & PRINTK_PENDING_SCHED) {
2478 char *buf = __get_cpu_var(printk_sched_buf);
2479 printk(KERN_WARNING "[sched_delayed] %s", buf);
2482 if (pending & PRINTK_PENDING_WAKEUP)
2483 wake_up_interruptible(&log_wait);
2486 static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
2487 .func = wake_up_klogd_work_func,
2488 .flags = IRQ_WORK_LAZY,
2491 void wake_up_klogd(void)
2494 if (waitqueue_active(&log_wait)) {
2495 this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
2496 irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
2501 int printk_deferred(const char *fmt, ...)
2503 unsigned long flags;
2508 local_irq_save(flags);
2509 buf = __get_cpu_var(printk_sched_buf);
2511 va_start(args, fmt);
2512 r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
2515 __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
2516 irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
2517 local_irq_restore(flags);
2523 * printk rate limiting, lifted from the networking subsystem.
2525 * This enforces a rate limit: not more than 10 kernel messages
2526 * every 5s to make a denial-of-service attack impossible.
2528 DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
2530 int __printk_ratelimit(const char *func)
2532 return ___ratelimit(&printk_ratelimit_state, func);
2534 EXPORT_SYMBOL(__printk_ratelimit);
2537 * printk_timed_ratelimit - caller-controlled printk ratelimiting
2538 * @caller_jiffies: pointer to caller's state
2539 * @interval_msecs: minimum interval between prints
2541 * printk_timed_ratelimit() returns true if more than @interval_msecs
2542 * milliseconds have elapsed since the last time printk_timed_ratelimit()
2545 bool printk_timed_ratelimit(unsigned long *caller_jiffies,
2546 unsigned int interval_msecs)
2548 if (*caller_jiffies == 0
2549 || !time_in_range(jiffies, *caller_jiffies,
2551 + msecs_to_jiffies(interval_msecs))) {
2552 *caller_jiffies = jiffies;
2557 EXPORT_SYMBOL(printk_timed_ratelimit);
2559 static DEFINE_SPINLOCK(dump_list_lock);
2560 static LIST_HEAD(dump_list);
2563 * kmsg_dump_register - register a kernel log dumper.
2564 * @dumper: pointer to the kmsg_dumper structure
2566 * Adds a kernel log dumper to the system. The dump callback in the
2567 * structure will be called when the kernel oopses or panics and must be
2568 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
2570 int kmsg_dump_register(struct kmsg_dumper *dumper)
2572 unsigned long flags;
2575 /* The dump callback needs to be set */
2579 spin_lock_irqsave(&dump_list_lock, flags);
2580 /* Don't allow registering multiple times */
2581 if (!dumper->registered) {
2582 dumper->registered = 1;
2583 list_add_tail_rcu(&dumper->list, &dump_list);
2586 spin_unlock_irqrestore(&dump_list_lock, flags);
2590 EXPORT_SYMBOL_GPL(kmsg_dump_register);
2593 * kmsg_dump_unregister - unregister a kmsg dumper.
2594 * @dumper: pointer to the kmsg_dumper structure
2596 * Removes a dump device from the system. Returns zero on success and
2597 * %-EINVAL otherwise.
2599 int kmsg_dump_unregister(struct kmsg_dumper *dumper)
2601 unsigned long flags;
2604 spin_lock_irqsave(&dump_list_lock, flags);
2605 if (dumper->registered) {
2606 dumper->registered = 0;
2607 list_del_rcu(&dumper->list);
2610 spin_unlock_irqrestore(&dump_list_lock, flags);
2615 EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
2617 static bool always_kmsg_dump;
2618 module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
2621 * kmsg_dump - dump kernel log to kernel message dumpers.
2622 * @reason: the reason (oops, panic etc) for dumping
2624 * Call each of the registered dumper's dump() callback, which can
2625 * retrieve the kmsg records with kmsg_dump_get_line() or
2626 * kmsg_dump_get_buffer().
2628 void kmsg_dump(enum kmsg_dump_reason reason)
2630 struct kmsg_dumper *dumper;
2631 unsigned long flags;
2633 if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
2637 list_for_each_entry_rcu(dumper, &dump_list, list) {
2638 if (dumper->max_reason && reason > dumper->max_reason)
2641 /* initialize iterator with data about the stored records */
2642 dumper->active = true;
2644 raw_spin_lock_irqsave(&logbuf_lock, flags);
2645 dumper->cur_seq = clear_seq;
2646 dumper->cur_idx = clear_idx;
2647 dumper->next_seq = log_next_seq;
2648 dumper->next_idx = log_next_idx;
2649 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2651 /* invoke dumper which will iterate over records */
2652 dumper->dump(dumper, reason);
2654 /* reset iterator */
2655 dumper->active = false;
2661 * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
2662 * @dumper: registered kmsg dumper
2663 * @syslog: include the "<4>" prefixes
2664 * @line: buffer to copy the line to
2665 * @size: maximum size of the buffer
2666 * @len: length of line placed into buffer
2668 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2669 * record, and copy one record into the provided buffer.
2671 * Consecutive calls will return the next available record moving
2672 * towards the end of the buffer with the youngest messages.
2674 * A return value of FALSE indicates that there are no more records to
2677 * The function is similar to kmsg_dump_get_line(), but grabs no locks.
2679 bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
2680 char *line, size_t size, size_t *len)
2686 if (!dumper->active)
2689 if (dumper->cur_seq < log_first_seq) {
2690 /* messages are gone, move to first available one */
2691 dumper->cur_seq = log_first_seq;
2692 dumper->cur_idx = log_first_idx;
2696 if (dumper->cur_seq >= log_next_seq)
2699 msg = log_from_idx(dumper->cur_idx);
2700 l = msg_print_text(msg, 0, syslog, line, size);
2702 dumper->cur_idx = log_next(dumper->cur_idx);
2712 * kmsg_dump_get_line - retrieve one kmsg log line
2713 * @dumper: registered kmsg dumper
2714 * @syslog: include the "<4>" prefixes
2715 * @line: buffer to copy the line to
2716 * @size: maximum size of the buffer
2717 * @len: length of line placed into buffer
2719 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2720 * record, and copy one record into the provided buffer.
2722 * Consecutive calls will return the next available record moving
2723 * towards the end of the buffer with the youngest messages.
2725 * A return value of FALSE indicates that there are no more records to
2728 bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
2729 char *line, size_t size, size_t *len)
2731 unsigned long flags;
2734 raw_spin_lock_irqsave(&logbuf_lock, flags);
2735 ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
2736 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2740 EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
2743 * kmsg_dump_get_buffer - copy kmsg log lines
2744 * @dumper: registered kmsg dumper
2745 * @syslog: include the "<4>" prefixes
2746 * @buf: buffer to copy the line to
2747 * @size: maximum size of the buffer
2748 * @len: length of line placed into buffer
2750 * Start at the end of the kmsg buffer and fill the provided buffer
2751 * with as many of the the *youngest* kmsg records that fit into it.
2752 * If the buffer is large enough, all available kmsg records will be
2753 * copied with a single call.
2755 * Consecutive calls will fill the buffer with the next block of
2756 * available older records, not including the earlier retrieved ones.
2758 * A return value of FALSE indicates that there are no more records to
2761 bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
2762 char *buf, size_t size, size_t *len)
2764 unsigned long flags;
2769 enum log_flags prev;
2773 if (!dumper->active)
2776 raw_spin_lock_irqsave(&logbuf_lock, flags);
2777 if (dumper->cur_seq < log_first_seq) {
2778 /* messages are gone, move to first available one */
2779 dumper->cur_seq = log_first_seq;
2780 dumper->cur_idx = log_first_idx;
2784 if (dumper->cur_seq >= dumper->next_seq) {
2785 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2789 /* calculate length of entire buffer */
2790 seq = dumper->cur_seq;
2791 idx = dumper->cur_idx;
2793 while (seq < dumper->next_seq) {
2794 struct log *msg = log_from_idx(idx);
2796 l += msg_print_text(msg, prev, true, NULL, 0);
2797 idx = log_next(idx);
2802 /* move first record forward until length fits into the buffer */
2803 seq = dumper->cur_seq;
2804 idx = dumper->cur_idx;
2806 while (l > size && seq < dumper->next_seq) {
2807 struct log *msg = log_from_idx(idx);
2809 l -= msg_print_text(msg, prev, true, NULL, 0);
2810 idx = log_next(idx);
2815 /* last message in next interation */
2821 while (seq < dumper->next_seq) {
2822 struct log *msg = log_from_idx(idx);
2824 l += msg_print_text(msg, prev, syslog, buf + l, size - l);
2825 idx = log_next(idx);
2830 dumper->next_seq = next_seq;
2831 dumper->next_idx = next_idx;
2833 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2839 EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
2842 * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
2843 * @dumper: registered kmsg dumper
2845 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2846 * kmsg_dump_get_buffer() can be called again and used multiple
2847 * times within the same dumper.dump() callback.
2849 * The function is similar to kmsg_dump_rewind(), but grabs no locks.
2851 void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
2853 dumper->cur_seq = clear_seq;
2854 dumper->cur_idx = clear_idx;
2855 dumper->next_seq = log_next_seq;
2856 dumper->next_idx = log_next_idx;
2860 * kmsg_dump_rewind - reset the interator
2861 * @dumper: registered kmsg dumper
2863 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2864 * kmsg_dump_get_buffer() can be called again and used multiple
2865 * times within the same dumper.dump() callback.
2867 void kmsg_dump_rewind(struct kmsg_dumper *dumper)
2869 unsigned long flags;
2871 raw_spin_lock_irqsave(&logbuf_lock, flags);
2872 kmsg_dump_rewind_nolock(dumper);
2873 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2875 EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
2877 static char dump_stack_arch_desc_str[128];
2880 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
2881 * @fmt: printf-style format string
2882 * @...: arguments for the format string
2884 * The configured string will be printed right after utsname during task
2885 * dumps. Usually used to add arch-specific system identifiers. If an
2886 * arch wants to make use of such an ID string, it should initialize this
2887 * as soon as possible during boot.
2889 void __init dump_stack_set_arch_desc(const char *fmt, ...)
2893 va_start(args, fmt);
2894 vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
2900 * dump_stack_print_info - print generic debug info for dump_stack()
2901 * @log_lvl: log level
2903 * Arch-specific dump_stack() implementations can use this function to
2904 * print out the same debug information as the generic dump_stack().
2906 void dump_stack_print_info(const char *log_lvl)
2908 printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
2909 log_lvl, raw_smp_processor_id(), current->pid, current->comm,
2910 print_tainted(), init_utsname()->release,
2911 (int)strcspn(init_utsname()->version, " "),
2912 init_utsname()->version);
2914 if (dump_stack_arch_desc_str[0] != '\0')
2915 printk("%sHardware name: %s\n",
2916 log_lvl, dump_stack_arch_desc_str);
2918 print_worker_info(log_lvl, current);
2922 * show_regs_print_info - print generic debug info for show_regs()
2923 * @log_lvl: log level
2925 * show_regs() implementations can use this function to print out generic
2926 * debug information.
2928 void show_regs_print_info(const char *log_lvl)
2930 dump_stack_print_info(log_lvl);
2932 printk("%stask: %p ti: %p task.ti: %p\n",
2933 log_lvl, current, current_thread_info(),
2934 task_thread_info(current));