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[4] = {
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 */
73 * Low level drivers may need that to know if they can schedule in
74 * their unblank() callback or not. So let's export it.
77 EXPORT_SYMBOL(oops_in_progress);
80 * console_sem protects the console_drivers list, and also
81 * provides serialisation for access to the entire console
84 static DEFINE_SEMAPHORE(console_sem);
85 struct console *console_drivers;
86 EXPORT_SYMBOL_GPL(console_drivers);
89 static struct lockdep_map console_lock_dep_map = {
90 .name = "console_lock"
95 * This is used for debugging the mess that is the VT code by
96 * keeping track if we have the console semaphore held. It's
97 * definitely not the perfect debug tool (we don't know if _WE_
98 * hold it are racing, but it helps tracking those weird code
99 * path in the console code where we end up in places I want
100 * locked without the console sempahore held
102 static int console_locked, console_suspended;
105 * If exclusive_console is non-NULL then only this console is to be printed to.
107 static struct console *exclusive_console;
110 * Array of consoles built from command line options (console=)
112 struct console_cmdline
114 char name[16]; /* Name of the driver */
115 int index; /* Minor dev. to use */
116 char *options; /* Options for the driver */
117 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
118 char *brl_options; /* Options for braille driver */
122 #define MAX_CMDLINECONSOLES 8
124 static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
125 static int selected_console = -1;
126 static int preferred_console = -1;
127 int console_set_on_cmdline;
128 EXPORT_SYMBOL(console_set_on_cmdline);
130 /* Flag: console code may call schedule() */
131 static int console_may_schedule;
134 * The printk log buffer consists of a chain of concatenated variable
135 * length records. Every record starts with a record header, containing
136 * the overall length of the record.
138 * The heads to the first and last entry in the buffer, as well as the
139 * sequence numbers of these both entries are maintained when messages
142 * If the heads indicate available messages, the length in the header
143 * tells the start next message. A length == 0 for the next message
144 * indicates a wrap-around to the beginning of the buffer.
146 * Every record carries the monotonic timestamp in microseconds, as well as
147 * the standard userspace syslog level and syslog facility. The usual
148 * kernel messages use LOG_KERN; userspace-injected messages always carry
149 * a matching syslog facility, by default LOG_USER. The origin of every
150 * message can be reliably determined that way.
152 * The human readable log message directly follows the message header. The
153 * length of the message text is stored in the header, the stored message
156 * Optionally, a message can carry a dictionary of properties (key/value pairs),
157 * to provide userspace with a machine-readable message context.
159 * Examples for well-defined, commonly used property names are:
160 * DEVICE=b12:8 device identifier
164 * +sound:card0 subsystem:devname
165 * SUBSYSTEM=pci driver-core subsystem name
167 * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
168 * follows directly after a '=' character. Every property is terminated by
169 * a '\0' character. The last property is not terminated.
171 * Example of a message structure:
172 * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec
173 * 0008 34 00 record is 52 bytes long
174 * 000a 0b 00 text is 11 bytes long
175 * 000c 1f 00 dictionary is 23 bytes long
176 * 000e 03 00 LOG_KERN (facility) LOG_ERR (level)
177 * 0010 69 74 27 73 20 61 20 6c "it's a l"
179 * 001b 44 45 56 49 43 "DEVIC"
180 * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D"
181 * 52 49 56 45 52 3d 62 75 "RIVER=bu"
183 * 0032 00 00 00 padding to next message header
185 * The 'struct log' buffer header must never be directly exported to
186 * userspace, it is a kernel-private implementation detail that might
187 * need to be changed in the future, when the requirements change.
189 * /dev/kmsg exports the structured data in the following line format:
190 * "level,sequnum,timestamp;<message text>\n"
192 * The optional key/value pairs are attached as continuation lines starting
193 * with a space character and terminated by a newline. All possible
194 * non-prinatable characters are escaped in the "\xff" notation.
196 * Users of the export format should ignore possible additional values
197 * separated by ',', and find the message after the ';' character.
201 LOG_NOCONS = 1, /* already flushed, do not print to console */
202 LOG_NEWLINE = 2, /* text ended with a newline */
203 LOG_PREFIX = 4, /* text started with a prefix */
204 LOG_CONT = 8, /* text is a fragment of a continuation line */
208 u64 ts_nsec; /* timestamp in nanoseconds */
209 u16 len; /* length of entire record */
210 u16 text_len; /* length of text buffer */
211 u16 dict_len; /* length of dictionary buffer */
212 u8 facility; /* syslog facility */
213 u8 flags:5; /* internal record flags */
214 u8 level:3; /* syslog level */
215 #ifdef CONFIG_PRINTK_PROCESS
216 char process[16]; /* process name */
217 pid_t pid; /* process id */
219 u8 in_interrupt; /* interrupt context */
224 * The logbuf_lock protects kmsg buffer, indices, counters. It is also
225 * used in interesting ways to provide interlocking in console_unlock();
227 static DEFINE_RAW_SPINLOCK(logbuf_lock);
230 DECLARE_WAIT_QUEUE_HEAD(log_wait);
231 /* the next printk record to read by syslog(READ) or /proc/kmsg */
232 static u64 syslog_seq;
233 static u32 syslog_idx;
234 static enum log_flags syslog_prev;
235 static size_t syslog_partial;
237 /* index and sequence number of the first record stored in the buffer */
238 static u64 log_first_seq;
239 static u32 log_first_idx;
241 /* index and sequence number of the next record to store in the buffer */
242 static u64 log_next_seq;
243 static u32 log_next_idx;
245 /* the next printk record to write to the console */
246 static u64 console_seq;
247 static u32 console_idx;
248 static enum log_flags console_prev;
250 /* the next printk record to read after the last 'clear' command */
251 static u64 clear_seq;
252 static u32 clear_idx;
254 #ifdef CONFIG_PRINTK_PROCESS
255 #define PREFIX_MAX 48
257 #define PREFIX_MAX 32
259 #define LOG_LINE_MAX 1024 - PREFIX_MAX
262 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
265 #define LOG_ALIGN __alignof__(struct log)
267 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
268 static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
269 static char *log_buf = __log_buf;
270 static u32 log_buf_len = __LOG_BUF_LEN;
272 /* cpu currently holding logbuf_lock */
273 static volatile unsigned int logbuf_cpu = UINT_MAX;
275 /* human readable text of the record */
276 static char *log_text(const struct log *msg)
278 return (char *)msg + sizeof(struct log);
281 /* optional key/value pair dictionary attached to the record */
282 static char *log_dict(const struct log *msg)
284 return (char *)msg + sizeof(struct log) + msg->text_len;
287 /* get record by index; idx must point to valid msg */
288 static struct log *log_from_idx(u32 idx)
290 struct log *msg = (struct log *)(log_buf + idx);
293 * A length == 0 record is the end of buffer marker. Wrap around and
294 * read the message at the start of the buffer.
297 return (struct log *)log_buf;
301 /* get next record; idx must point to valid msg */
302 static u32 log_next(u32 idx)
304 struct log *msg = (struct log *)(log_buf + idx);
306 /* length == 0 indicates the end of the buffer; wrap */
308 * A length == 0 record is the end of buffer marker. Wrap around and
309 * read the message at the start of the buffer as *this* one, and
310 * return the one after that.
313 msg = (struct log *)log_buf;
316 return idx + msg->len;
319 #ifdef CONFIG_PRINTK_PROCESS
320 static bool printk_process = 1;
321 static size_t print_process(const struct log *msg, char *buf)
327 return snprintf(NULL, 0, "%c[%1d:%15s:%5d] ", ' ', 0, " ", 0);
329 return sprintf(buf, "%c[%1d:%15s:%5d] ",
330 msg->in_interrupt ? 'I' : ' ',
335 module_param_named(process, printk_process, bool, S_IRUGO | S_IWUSR);
338 #ifdef CONFIG_RK_LAST_LOG
339 extern void rk_last_log_text(char *text, size_t size);
340 static char rk_text[1024];
341 static size_t msg_print_text(const struct log *msg, enum log_flags prev,
342 bool syslog, char *buf, size_t size);
344 /* insert record into the buffer, discard old ones, update heads */
345 static void log_store(int facility, int level,
346 enum log_flags flags, u64 ts_nsec,
347 const char *dict, u16 dict_len,
348 const char *text, u16 text_len)
353 /* number of '\0' padding bytes to next message */
354 size = sizeof(struct log) + text_len + dict_len;
355 pad_len = (-size) & (LOG_ALIGN - 1);
358 while (log_first_seq < log_next_seq) {
361 if (log_next_idx > log_first_idx)
362 free = max(log_buf_len - log_next_idx, log_first_idx);
364 free = log_first_idx - log_next_idx;
366 if (free > size + sizeof(struct log))
369 /* drop old messages until we have enough contiuous space */
370 log_first_idx = log_next(log_first_idx);
374 if (log_next_idx + size + sizeof(struct log) >= log_buf_len) {
376 * This message + an additional empty header does not fit
377 * at the end of the buffer. Add an empty header with len == 0
378 * to signify a wrap around.
380 memset(log_buf + log_next_idx, 0, sizeof(struct log));
385 msg = (struct log *)(log_buf + log_next_idx);
386 memcpy(log_text(msg), text, text_len);
387 msg->text_len = text_len;
388 memcpy(log_dict(msg), dict, dict_len);
389 msg->dict_len = dict_len;
390 msg->facility = facility;
391 msg->level = level & 7;
392 msg->flags = flags & 0x1f;
394 msg->ts_nsec = ts_nsec;
396 msg->ts_nsec = local_clock();
397 memset(log_dict(msg) + dict_len, 0, pad_len);
398 msg->len = sizeof(struct log) + text_len + dict_len + pad_len;
400 #ifdef CONFIG_PRINTK_PROCESS
401 if (printk_process) {
402 strncpy(msg->process, current->comm, sizeof(msg->process)-1);
403 msg->process[sizeof(msg->process) - 1] = '\0';
404 msg->pid = task_pid_nr(current);
405 msg->cpu = smp_processor_id();
406 msg->in_interrupt = in_interrupt() ? 1 : 0;
410 #ifdef CONFIG_RK_LAST_LOG
411 size = msg_print_text(msg, msg->flags, true, rk_text, sizeof(rk_text));
412 rk_last_log_text(rk_text, size);
415 log_next_idx += msg->len;
419 #ifdef CONFIG_SECURITY_DMESG_RESTRICT
420 int dmesg_restrict = 1;
425 static int syslog_action_restricted(int type)
430 * Unless restricted, we allow "read all" and "get buffer size"
433 return type != SYSLOG_ACTION_READ_ALL &&
434 type != SYSLOG_ACTION_SIZE_BUFFER;
437 static int check_syslog_permissions(int type, bool from_file)
440 * If this is from /proc/kmsg and we've already opened it, then we've
441 * already done the capabilities checks at open time.
443 if (from_file && type != SYSLOG_ACTION_OPEN)
446 if (syslog_action_restricted(type)) {
447 if (capable(CAP_SYSLOG))
450 * For historical reasons, accept CAP_SYS_ADMIN too, with
453 if (capable(CAP_SYS_ADMIN)) {
454 pr_warn_once("%s (%d): Attempt to access syslog with "
455 "CAP_SYS_ADMIN but no CAP_SYSLOG "
457 current->comm, task_pid_nr(current));
462 return security_syslog(type);
466 /* /dev/kmsg - userspace message inject/listen interface */
467 struct devkmsg_user {
475 static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
476 unsigned long count, loff_t pos)
480 int level = default_message_loglevel;
481 int facility = 1; /* LOG_USER */
482 size_t len = iov_length(iv, count);
485 if (len > LOG_LINE_MAX)
487 buf = kmalloc(len+1, GFP_KERNEL);
492 for (i = 0; i < count; i++) {
493 if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) {
497 line += iv[i].iov_len;
501 * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
502 * the decimal value represents 32bit, the lower 3 bit are the log
503 * level, the rest are the log facility.
505 * If no prefix or no userspace facility is specified, we
506 * enforce LOG_USER, to be able to reliably distinguish
507 * kernel-generated messages from userspace-injected ones.
510 if (line[0] == '<') {
513 i = simple_strtoul(line+1, &endp, 10);
514 if (endp && endp[0] == '>') {
525 printk_emit(facility, level, NULL, 0, "%s", line);
531 static ssize_t devkmsg_read(struct file *file, char __user *buf,
532 size_t count, loff_t *ppos)
534 struct devkmsg_user *user = file->private_data;
545 ret = mutex_lock_interruptible(&user->lock);
548 raw_spin_lock_irq(&logbuf_lock);
549 while (user->seq == log_next_seq) {
550 if (file->f_flags & O_NONBLOCK) {
552 raw_spin_unlock_irq(&logbuf_lock);
556 raw_spin_unlock_irq(&logbuf_lock);
557 ret = wait_event_interruptible(log_wait,
558 user->seq != log_next_seq);
561 raw_spin_lock_irq(&logbuf_lock);
564 if (user->seq < log_first_seq) {
565 /* our last seen message is gone, return error and reset */
566 user->idx = log_first_idx;
567 user->seq = log_first_seq;
569 raw_spin_unlock_irq(&logbuf_lock);
573 msg = log_from_idx(user->idx);
574 ts_usec = msg->ts_nsec;
575 do_div(ts_usec, 1000);
578 * If we couldn't merge continuation line fragments during the print,
579 * export the stored flags to allow an optional external merge of the
580 * records. Merging the records isn't always neccessarily correct, like
581 * when we hit a race during printing. In most cases though, it produces
582 * better readable output. 'c' in the record flags mark the first
583 * fragment of a line, '+' the following.
585 if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT))
587 else if ((msg->flags & LOG_CONT) ||
588 ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
591 len = sprintf(user->buf, "%u,%llu,%llu,%c;",
592 (msg->facility << 3) | msg->level,
593 user->seq, ts_usec, cont);
594 user->prev = msg->flags;
596 /* escape non-printable characters */
597 for (i = 0; i < msg->text_len; i++) {
598 unsigned char c = log_text(msg)[i];
600 if (c < ' ' || c >= 127 || c == '\\')
601 len += sprintf(user->buf + len, "\\x%02x", c);
603 user->buf[len++] = c;
605 user->buf[len++] = '\n';
610 for (i = 0; i < msg->dict_len; i++) {
611 unsigned char c = log_dict(msg)[i];
614 user->buf[len++] = ' ';
619 user->buf[len++] = '\n';
624 if (c < ' ' || c >= 127 || c == '\\') {
625 len += sprintf(user->buf + len, "\\x%02x", c);
629 user->buf[len++] = c;
631 user->buf[len++] = '\n';
634 user->idx = log_next(user->idx);
636 raw_spin_unlock_irq(&logbuf_lock);
643 if (copy_to_user(buf, user->buf, len)) {
649 mutex_unlock(&user->lock);
653 static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
655 struct devkmsg_user *user = file->private_data;
663 raw_spin_lock_irq(&logbuf_lock);
666 /* the first record */
667 user->idx = log_first_idx;
668 user->seq = log_first_seq;
672 * The first record after the last SYSLOG_ACTION_CLEAR,
673 * like issued by 'dmesg -c'. Reading /dev/kmsg itself
674 * changes no global state, and does not clear anything.
676 user->idx = clear_idx;
677 user->seq = clear_seq;
680 /* after the last record */
681 user->idx = log_next_idx;
682 user->seq = log_next_seq;
687 raw_spin_unlock_irq(&logbuf_lock);
691 static unsigned int devkmsg_poll(struct file *file, poll_table *wait)
693 struct devkmsg_user *user = file->private_data;
697 return POLLERR|POLLNVAL;
699 poll_wait(file, &log_wait, wait);
701 raw_spin_lock_irq(&logbuf_lock);
702 if (user->seq < log_next_seq) {
703 /* return error when data has vanished underneath us */
704 if (user->seq < log_first_seq)
705 ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI;
707 ret = POLLIN|POLLRDNORM;
709 raw_spin_unlock_irq(&logbuf_lock);
714 static int devkmsg_open(struct inode *inode, struct file *file)
716 struct devkmsg_user *user;
719 /* write-only does not need any file context */
720 if ((file->f_flags & O_ACCMODE) == O_WRONLY)
723 err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
728 user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL);
732 mutex_init(&user->lock);
734 raw_spin_lock_irq(&logbuf_lock);
735 user->idx = log_first_idx;
736 user->seq = log_first_seq;
737 raw_spin_unlock_irq(&logbuf_lock);
739 file->private_data = user;
743 static int devkmsg_release(struct inode *inode, struct file *file)
745 struct devkmsg_user *user = file->private_data;
750 mutex_destroy(&user->lock);
755 const struct file_operations kmsg_fops = {
756 .open = devkmsg_open,
757 .read = devkmsg_read,
758 .aio_write = devkmsg_writev,
759 .llseek = devkmsg_llseek,
760 .poll = devkmsg_poll,
761 .release = devkmsg_release,
766 * This appends the listed symbols to /proc/vmcoreinfo
768 * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
769 * obtain access to symbols that are otherwise very difficult to locate. These
770 * symbols are specifically used so that utilities can access and extract the
771 * dmesg log from a vmcore file after a crash.
773 void log_buf_kexec_setup(void)
775 VMCOREINFO_SYMBOL(log_buf);
776 VMCOREINFO_SYMBOL(log_buf_len);
777 VMCOREINFO_SYMBOL(log_first_idx);
778 VMCOREINFO_SYMBOL(log_next_idx);
780 * Export struct log size and field offsets. User space tools can
781 * parse it and detect any changes to structure down the line.
783 VMCOREINFO_STRUCT_SIZE(log);
784 VMCOREINFO_OFFSET(log, ts_nsec);
785 VMCOREINFO_OFFSET(log, len);
786 VMCOREINFO_OFFSET(log, text_len);
787 VMCOREINFO_OFFSET(log, dict_len);
791 /* requested log_buf_len from kernel cmdline */
792 static unsigned long __initdata new_log_buf_len;
794 /* save requested log_buf_len since it's too early to process it */
795 static int __init log_buf_len_setup(char *str)
797 unsigned size = memparse(str, &str);
800 size = roundup_pow_of_two(size);
801 if (size > log_buf_len)
802 new_log_buf_len = size;
806 early_param("log_buf_len", log_buf_len_setup);
808 void __init setup_log_buf(int early)
814 if (!new_log_buf_len)
820 mem = memblock_alloc(new_log_buf_len, PAGE_SIZE);
823 new_log_buf = __va(mem);
825 new_log_buf = alloc_bootmem_nopanic(new_log_buf_len);
828 if (unlikely(!new_log_buf)) {
829 pr_err("log_buf_len: %ld bytes not available\n",
834 raw_spin_lock_irqsave(&logbuf_lock, flags);
835 log_buf_len = new_log_buf_len;
836 log_buf = new_log_buf;
838 free = __LOG_BUF_LEN - log_next_idx;
839 memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
840 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
842 pr_info("log_buf_len: %d\n", log_buf_len);
843 pr_info("early log buf free: %d(%d%%)\n",
844 free, (free * 100) / __LOG_BUF_LEN);
847 static bool __read_mostly ignore_loglevel;
849 static int __init ignore_loglevel_setup(char *str)
852 printk(KERN_INFO "debug: ignoring loglevel setting.\n");
857 early_param("ignore_loglevel", ignore_loglevel_setup);
858 module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR);
859 MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to"
860 "print all kernel messages to the console.");
862 #ifdef CONFIG_BOOT_PRINTK_DELAY
864 static int boot_delay; /* msecs delay after each printk during bootup */
865 static unsigned long long loops_per_msec; /* based on boot_delay */
867 static int __init boot_delay_setup(char *str)
871 lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */
872 loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
874 get_option(&str, &boot_delay);
875 if (boot_delay > 10 * 1000)
878 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
879 "HZ: %d, loops_per_msec: %llu\n",
880 boot_delay, preset_lpj, lpj, HZ, loops_per_msec);
883 __setup("boot_delay=", boot_delay_setup);
885 static void boot_delay_msec(int level)
887 unsigned long long k;
888 unsigned long timeout;
890 if ((boot_delay == 0 || system_state != SYSTEM_BOOTING)
891 || (level >= console_loglevel && !ignore_loglevel)) {
895 k = (unsigned long long)loops_per_msec * boot_delay;
897 timeout = jiffies + msecs_to_jiffies(boot_delay);
902 * use (volatile) jiffies to prevent
903 * compiler reduction; loop termination via jiffies
904 * is secondary and may or may not happen.
906 if (time_after(jiffies, timeout))
908 touch_nmi_watchdog();
912 static inline void boot_delay_msec(int level)
917 #if defined(CONFIG_PRINTK_TIME)
918 static bool printk_time = 1;
920 static bool printk_time;
922 module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
924 static size_t print_time(u64 ts, char *buf)
926 unsigned long rem_nsec;
931 rem_nsec = do_div(ts, 1000000000);
934 return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts);
936 return sprintf(buf, "[%5lu.%06lu] ",
937 (unsigned long)ts, rem_nsec / 1000);
940 static size_t print_prefix(const struct log *msg, bool syslog, char *buf)
943 unsigned int prefix = (msg->facility << 3) | msg->level;
947 len += sprintf(buf, "<%u>", prefix);
952 else if (prefix > 99)
959 len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
960 #ifdef CONFIG_PRINTK_PROCESS
961 len += print_process(msg, buf ? buf + len : NULL);
966 static size_t msg_print_text(const struct log *msg, enum log_flags prev,
967 bool syslog, char *buf, size_t size)
969 const char *text = log_text(msg);
970 size_t text_size = msg->text_len;
975 if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
978 if (msg->flags & LOG_CONT) {
979 if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE))
982 if (!(msg->flags & LOG_NEWLINE))
987 const char *next = memchr(text, '\n', text_size);
991 text_len = next - text;
993 text_size -= next - text;
995 text_len = text_size;
999 if (print_prefix(msg, syslog, NULL) +
1000 text_len + 1 >= size - len)
1004 len += print_prefix(msg, syslog, buf + len);
1005 memcpy(buf + len, text, text_len);
1007 if (next || newline)
1010 /* SYSLOG_ACTION_* buffer size only calculation */
1012 len += print_prefix(msg, syslog, NULL);
1014 if (next || newline)
1025 static int syslog_print(char __user *buf, int size)
1031 text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
1039 raw_spin_lock_irq(&logbuf_lock);
1040 if (syslog_seq < log_first_seq) {
1041 /* messages are gone, move to first one */
1042 syslog_seq = log_first_seq;
1043 syslog_idx = log_first_idx;
1047 if (syslog_seq == log_next_seq) {
1048 raw_spin_unlock_irq(&logbuf_lock);
1052 skip = syslog_partial;
1053 msg = log_from_idx(syslog_idx);
1054 n = msg_print_text(msg, syslog_prev, true, text,
1055 LOG_LINE_MAX + PREFIX_MAX);
1056 if (n - syslog_partial <= size) {
1057 /* message fits into buffer, move forward */
1058 syslog_idx = log_next(syslog_idx);
1060 syslog_prev = msg->flags;
1061 n -= syslog_partial;
1064 /* partial read(), remember position */
1066 syslog_partial += n;
1069 raw_spin_unlock_irq(&logbuf_lock);
1074 if (copy_to_user(buf, text + skip, n)) {
1089 static int syslog_print_all(char __user *buf, int size, bool clear)
1094 text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
1098 raw_spin_lock_irq(&logbuf_lock);
1103 enum log_flags prev;
1105 if (clear_seq < log_first_seq) {
1106 /* messages are gone, move to first available one */
1107 clear_seq = log_first_seq;
1108 clear_idx = log_first_idx;
1112 * Find first record that fits, including all following records,
1113 * into the user-provided buffer for this dump.
1118 while (seq < log_next_seq) {
1119 struct log *msg = log_from_idx(idx);
1121 len += msg_print_text(msg, prev, true, NULL, 0);
1123 idx = log_next(idx);
1127 /* move first record forward until length fits into the buffer */
1131 while (len > size && seq < log_next_seq) {
1132 struct log *msg = log_from_idx(idx);
1134 len -= msg_print_text(msg, prev, true, NULL, 0);
1136 idx = log_next(idx);
1140 /* last message fitting into this dump */
1141 next_seq = log_next_seq;
1145 while (len >= 0 && seq < next_seq) {
1146 struct log *msg = log_from_idx(idx);
1149 textlen = msg_print_text(msg, prev, true, text,
1150 LOG_LINE_MAX + PREFIX_MAX);
1155 idx = log_next(idx);
1159 raw_spin_unlock_irq(&logbuf_lock);
1160 if (copy_to_user(buf + len, text, textlen))
1164 raw_spin_lock_irq(&logbuf_lock);
1166 if (seq < log_first_seq) {
1167 /* messages are gone, move to next one */
1168 seq = log_first_seq;
1169 idx = log_first_idx;
1176 clear_seq = log_next_seq;
1177 clear_idx = log_next_idx;
1179 raw_spin_unlock_irq(&logbuf_lock);
1185 int do_syslog(int type, char __user *buf, int len, bool from_file)
1188 static int saved_console_loglevel = -1;
1191 error = check_syslog_permissions(type, from_file);
1195 error = security_syslog(type);
1200 case SYSLOG_ACTION_CLOSE: /* Close log */
1202 case SYSLOG_ACTION_OPEN: /* Open log */
1204 case SYSLOG_ACTION_READ: /* Read from log */
1206 if (!buf || len < 0)
1211 if (!access_ok(VERIFY_WRITE, buf, len)) {
1215 error = wait_event_interruptible(log_wait,
1216 syslog_seq != log_next_seq);
1219 error = syslog_print(buf, len);
1221 /* Read/clear last kernel messages */
1222 case SYSLOG_ACTION_READ_CLEAR:
1225 /* Read last kernel messages */
1226 case SYSLOG_ACTION_READ_ALL:
1228 if (!buf || len < 0)
1233 if (!access_ok(VERIFY_WRITE, buf, len)) {
1237 error = syslog_print_all(buf, len, clear);
1239 /* Clear ring buffer */
1240 case SYSLOG_ACTION_CLEAR:
1241 syslog_print_all(NULL, 0, true);
1243 /* Disable logging to console */
1244 case SYSLOG_ACTION_CONSOLE_OFF:
1245 if (saved_console_loglevel == -1)
1246 saved_console_loglevel = console_loglevel;
1247 console_loglevel = minimum_console_loglevel;
1249 /* Enable logging to console */
1250 case SYSLOG_ACTION_CONSOLE_ON:
1251 if (saved_console_loglevel != -1) {
1252 console_loglevel = saved_console_loglevel;
1253 saved_console_loglevel = -1;
1256 /* Set level of messages printed to console */
1257 case SYSLOG_ACTION_CONSOLE_LEVEL:
1259 if (len < 1 || len > 8)
1261 if (len < minimum_console_loglevel)
1262 len = minimum_console_loglevel;
1263 console_loglevel = len;
1264 /* Implicitly re-enable logging to console */
1265 saved_console_loglevel = -1;
1268 /* Number of chars in the log buffer */
1269 case SYSLOG_ACTION_SIZE_UNREAD:
1270 raw_spin_lock_irq(&logbuf_lock);
1271 if (syslog_seq < log_first_seq) {
1272 /* messages are gone, move to first one */
1273 syslog_seq = log_first_seq;
1274 syslog_idx = log_first_idx;
1280 * Short-cut for poll(/"proc/kmsg") which simply checks
1281 * for pending data, not the size; return the count of
1282 * records, not the length.
1284 error = log_next_idx - syslog_idx;
1286 u64 seq = syslog_seq;
1287 u32 idx = syslog_idx;
1288 enum log_flags prev = syslog_prev;
1291 while (seq < log_next_seq) {
1292 struct log *msg = log_from_idx(idx);
1294 error += msg_print_text(msg, prev, true, NULL, 0);
1295 idx = log_next(idx);
1299 error -= syslog_partial;
1301 raw_spin_unlock_irq(&logbuf_lock);
1303 /* Size of the log buffer */
1304 case SYSLOG_ACTION_SIZE_BUFFER:
1305 error = log_buf_len;
1315 SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
1317 return do_syslog(type, buf, len, SYSLOG_FROM_READER);
1321 * Call the console drivers, asking them to write out
1322 * log_buf[start] to log_buf[end - 1].
1323 * The console_lock must be held.
1325 static void call_console_drivers(int level, const char *text, size_t len)
1327 struct console *con;
1329 trace_console(text, len);
1331 if (level >= console_loglevel && !ignore_loglevel)
1333 if (!console_drivers)
1336 for_each_console(con) {
1337 if (exclusive_console && con != exclusive_console)
1339 if (!(con->flags & CON_ENABLED))
1343 if (!cpu_online(smp_processor_id()) &&
1344 !(con->flags & CON_ANYTIME))
1346 con->write(con, text, len);
1351 * Zap console related locks when oopsing. Only zap at most once
1352 * every 10 seconds, to leave time for slow consoles to print a
1355 static void zap_locks(void)
1357 static unsigned long oops_timestamp;
1359 if (time_after_eq(jiffies, oops_timestamp) &&
1360 !time_after(jiffies, oops_timestamp + 30 * HZ))
1363 oops_timestamp = jiffies;
1366 /* If a crash is occurring, make sure we can't deadlock */
1367 raw_spin_lock_init(&logbuf_lock);
1368 /* And make sure that we print immediately */
1369 sema_init(&console_sem, 1);
1372 /* Check if we have any console registered that can be called early in boot. */
1373 static int have_callable_console(void)
1375 struct console *con;
1377 for_each_console(con)
1378 if (con->flags & CON_ANYTIME)
1385 * Can we actually use the console at this time on this cpu?
1387 * Console drivers may assume that per-cpu resources have
1388 * been allocated. So unless they're explicitly marked as
1389 * being able to cope (CON_ANYTIME) don't call them until
1390 * this CPU is officially up.
1392 static inline int can_use_console(unsigned int cpu)
1394 return cpu_online(cpu) || have_callable_console();
1398 * Try to get console ownership to actually show the kernel
1399 * messages from a 'printk'. Return true (and with the
1400 * console_lock held, and 'console_locked' set) if it
1401 * is successful, false otherwise.
1403 * This gets called with the 'logbuf_lock' spinlock held and
1404 * interrupts disabled. It should return with 'lockbuf_lock'
1405 * released but interrupts still disabled.
1407 static int console_trylock_for_printk(unsigned int cpu)
1408 __releases(&logbuf_lock)
1410 int retval = 0, wake = 0;
1412 if (console_trylock()) {
1416 * If we can't use the console, we need to release
1417 * the console semaphore by hand to avoid flushing
1418 * the buffer. We need to hold the console semaphore
1419 * in order to do this test safely.
1421 if (!can_use_console(cpu)) {
1427 logbuf_cpu = UINT_MAX;
1428 raw_spin_unlock(&logbuf_lock);
1434 int printk_delay_msec __read_mostly;
1436 static inline void printk_delay(void)
1438 if (unlikely(printk_delay_msec)) {
1439 int m = printk_delay_msec;
1443 touch_nmi_watchdog();
1449 * Continuation lines are buffered, and not committed to the record buffer
1450 * until the line is complete, or a race forces it. The line fragments
1451 * though, are printed immediately to the consoles to ensure everything has
1452 * reached the console in case of a kernel crash.
1454 static struct cont {
1455 char buf[LOG_LINE_MAX];
1456 size_t len; /* length == 0 means unused buffer */
1457 size_t cons; /* bytes written to console */
1458 struct task_struct *owner; /* task of first print*/
1459 u64 ts_nsec; /* time of first print */
1460 u8 level; /* log level of first message */
1461 u8 facility; /* log level of first message */
1462 enum log_flags flags; /* prefix, newline flags */
1463 bool flushed:1; /* buffer sealed and committed */
1466 static void cont_flush(enum log_flags flags)
1475 * If a fragment of this line was directly flushed to the
1476 * console; wait for the console to pick up the rest of the
1477 * line. LOG_NOCONS suppresses a duplicated output.
1479 log_store(cont.facility, cont.level, flags | LOG_NOCONS,
1480 cont.ts_nsec, NULL, 0, cont.buf, cont.len);
1482 cont.flushed = true;
1485 * If no fragment of this line ever reached the console,
1486 * just submit it to the store and free the buffer.
1488 log_store(cont.facility, cont.level, flags, 0,
1489 NULL, 0, cont.buf, cont.len);
1494 static bool cont_add(int facility, int level, const char *text, size_t len)
1496 if (cont.len && cont.flushed)
1499 if (cont.len + len > sizeof(cont.buf)) {
1500 /* the line gets too long, split it up in separate records */
1501 cont_flush(LOG_CONT);
1506 cont.facility = facility;
1508 cont.owner = current;
1509 cont.ts_nsec = local_clock();
1512 cont.flushed = false;
1515 memcpy(cont.buf + cont.len, text, len);
1518 if (cont.len > (sizeof(cont.buf) * 80) / 100)
1519 cont_flush(LOG_CONT);
1524 static size_t cont_print_text(char *text, size_t size)
1529 if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) {
1530 textlen += print_time(cont.ts_nsec, text);
1531 #ifdef CONFIG_PRINTK_PROCESS
1532 *(text+textlen) = ' ';
1533 textlen += print_process(NULL, NULL);
1538 len = cont.len - cont.cons;
1542 memcpy(text + textlen, cont.buf + cont.cons, len);
1544 cont.cons = cont.len;
1548 if (cont.flags & LOG_NEWLINE)
1549 text[textlen++] = '\n';
1550 /* got everything, release buffer */
1556 asmlinkage int vprintk_emit(int facility, int level,
1557 const char *dict, size_t dictlen,
1558 const char *fmt, va_list args)
1560 static int recursion_bug;
1561 static char textbuf[LOG_LINE_MAX];
1562 char *text = textbuf;
1564 enum log_flags lflags = 0;
1565 unsigned long flags;
1567 int printed_len = 0;
1569 boot_delay_msec(level);
1572 /* This stops the holder of console_sem just where we want him */
1573 local_irq_save(flags);
1574 this_cpu = smp_processor_id();
1577 * Ouch, printk recursed into itself!
1579 if (unlikely(logbuf_cpu == this_cpu)) {
1581 * If a crash is occurring during printk() on this CPU,
1582 * then try to get the crash message out but make sure
1583 * we can't deadlock. Otherwise just return to avoid the
1584 * recursion and return - but flag the recursion so that
1585 * it can be printed at the next appropriate moment:
1587 if (!oops_in_progress && !lockdep_recursing(current)) {
1589 goto out_restore_irqs;
1595 raw_spin_lock(&logbuf_lock);
1596 logbuf_cpu = this_cpu;
1598 if (recursion_bug) {
1599 static const char recursion_msg[] =
1600 "BUG: recent printk recursion!";
1603 printed_len += strlen(recursion_msg);
1604 /* emit KERN_CRIT message */
1605 log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
1606 NULL, 0, recursion_msg, printed_len);
1610 * The printf needs to come first; we need the syslog
1611 * prefix which might be passed-in as a parameter.
1613 text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
1615 /* mark and strip a trailing newline */
1616 if (text_len && text[text_len-1] == '\n') {
1618 lflags |= LOG_NEWLINE;
1621 /* strip kernel syslog prefix and extract log level or control flags */
1622 if (facility == 0) {
1623 int kern_level = printk_get_level(text);
1626 const char *end_of_header = printk_skip_level(text);
1627 switch (kern_level) {
1630 level = kern_level - '0';
1631 case 'd': /* KERN_DEFAULT */
1632 lflags |= LOG_PREFIX;
1633 case 'c': /* KERN_CONT */
1636 text_len -= end_of_header - text;
1637 text = (char *)end_of_header;
1641 #ifdef CONFIG_EARLY_PRINTK_DIRECT
1646 level = default_message_loglevel;
1649 lflags |= LOG_PREFIX|LOG_NEWLINE;
1651 if (!(lflags & LOG_NEWLINE)) {
1653 * Flush the conflicting buffer. An earlier newline was missing,
1654 * or another task also prints continuation lines.
1656 if (cont.len && (lflags & LOG_PREFIX || cont.owner != current))
1657 cont_flush(LOG_NEWLINE);
1659 /* buffer line if possible, otherwise store it right away */
1660 if (!cont_add(facility, level, text, text_len))
1661 log_store(facility, level, lflags | LOG_CONT, 0,
1662 dict, dictlen, text, text_len);
1664 bool stored = false;
1667 * If an earlier newline was missing and it was the same task,
1668 * either merge it with the current buffer and flush, or if
1669 * there was a race with interrupts (prefix == true) then just
1670 * flush it out and store this line separately.
1672 if (cont.len && cont.owner == current) {
1673 if (!(lflags & LOG_PREFIX))
1674 stored = cont_add(facility, level, text, text_len);
1675 cont_flush(LOG_NEWLINE);
1679 log_store(facility, level, lflags, 0,
1680 dict, dictlen, text, text_len);
1682 printed_len += text_len;
1685 * Try to acquire and then immediately release the console semaphore.
1686 * The release will print out buffers and wake up /dev/kmsg and syslog()
1689 * The console_trylock_for_printk() function will release 'logbuf_lock'
1690 * regardless of whether it actually gets the console semaphore or not.
1692 if (console_trylock_for_printk(this_cpu))
1697 local_irq_restore(flags);
1701 EXPORT_SYMBOL(vprintk_emit);
1703 asmlinkage int vprintk(const char *fmt, va_list args)
1705 return vprintk_emit(0, -1, NULL, 0, fmt, args);
1707 EXPORT_SYMBOL(vprintk);
1709 asmlinkage int printk_emit(int facility, int level,
1710 const char *dict, size_t dictlen,
1711 const char *fmt, ...)
1716 va_start(args, fmt);
1717 r = vprintk_emit(facility, level, dict, dictlen, fmt, args);
1722 EXPORT_SYMBOL(printk_emit);
1725 * printk - print a kernel message
1726 * @fmt: format string
1728 * This is printk(). It can be called from any context. We want it to work.
1730 * We try to grab the console_lock. If we succeed, it's easy - we log the
1731 * output and call the console drivers. If we fail to get the semaphore, we
1732 * place the output into the log buffer and return. The current holder of
1733 * the console_sem will notice the new output in console_unlock(); and will
1734 * send it to the consoles before releasing the lock.
1736 * One effect of this deferred printing is that code which calls printk() and
1737 * then changes console_loglevel may break. This is because console_loglevel
1738 * is inspected when the actual printing occurs.
1743 * See the vsnprintf() documentation for format string extensions over C99.
1745 asmlinkage int printk(const char *fmt, ...)
1750 #ifdef CONFIG_KGDB_KDB
1751 if (unlikely(kdb_trap_printk)) {
1752 va_start(args, fmt);
1753 r = vkdb_printf(fmt, args);
1758 va_start(args, fmt);
1759 r = vprintk_emit(0, -1, NULL, 0, fmt, args);
1764 EXPORT_SYMBOL(printk);
1766 #if defined(CONFIG_RK_DEBUG_UART) && (CONFIG_RK_DEBUG_UART >= 0)
1767 void console_disable_suspend(void)
1769 console_suspended = 0;
1772 #else /* CONFIG_PRINTK */
1774 #define LOG_LINE_MAX 0
1775 #define PREFIX_MAX 0
1776 #define LOG_LINE_MAX 0
1777 static u64 syslog_seq;
1778 static u32 syslog_idx;
1779 static u64 console_seq;
1780 static u32 console_idx;
1781 static enum log_flags syslog_prev;
1782 static u64 log_first_seq;
1783 static u32 log_first_idx;
1784 static u64 log_next_seq;
1785 static enum log_flags console_prev;
1786 static struct cont {
1792 static struct log *log_from_idx(u32 idx) { return NULL; }
1793 static u32 log_next(u32 idx) { return 0; }
1794 static void call_console_drivers(int level, const char *text, size_t len) {}
1795 static size_t msg_print_text(const struct log *msg, enum log_flags prev,
1796 bool syslog, char *buf, size_t size) { return 0; }
1797 static size_t cont_print_text(char *text, size_t size) { return 0; }
1799 #endif /* CONFIG_PRINTK */
1801 #ifdef CONFIG_EARLY_PRINTK
1802 struct console *early_console;
1804 void early_vprintk(const char *fmt, va_list ap)
1806 if (early_console) {
1808 int n = vscnprintf(buf, sizeof(buf), fmt, ap);
1810 early_console->write(early_console, buf, n);
1814 asmlinkage void early_printk(const char *fmt, ...)
1819 early_vprintk(fmt, ap);
1824 static int __add_preferred_console(char *name, int idx, char *options,
1827 struct console_cmdline *c;
1831 * See if this tty is not yet registered, and
1832 * if we have a slot free.
1834 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
1835 if (strcmp(console_cmdline[i].name, name) == 0 &&
1836 console_cmdline[i].index == idx) {
1838 selected_console = i;
1841 if (i == MAX_CMDLINECONSOLES)
1844 selected_console = i;
1845 c = &console_cmdline[i];
1846 strlcpy(c->name, name, sizeof(c->name));
1847 c->options = options;
1848 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1849 c->brl_options = brl_options;
1855 * Set up a list of consoles. Called from init/main.c
1857 static int __init console_setup(char *str)
1859 char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
1860 char *s, *options, *brl_options = NULL;
1863 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1864 if (!memcmp(str, "brl,", 4)) {
1867 } else if (!memcmp(str, "brl=", 4)) {
1868 brl_options = str + 4;
1869 str = strchr(brl_options, ',');
1871 printk(KERN_ERR "need port name after brl=\n");
1879 * Decode str into name, index, options.
1881 if (str[0] >= '0' && str[0] <= '9') {
1882 strcpy(buf, "ttyS");
1883 strncpy(buf + 4, str, sizeof(buf) - 5);
1885 strncpy(buf, str, sizeof(buf) - 1);
1887 buf[sizeof(buf) - 1] = 0;
1888 if ((options = strchr(str, ',')) != NULL)
1891 if (!strcmp(str, "ttya"))
1892 strcpy(buf, "ttyS0");
1893 if (!strcmp(str, "ttyb"))
1894 strcpy(buf, "ttyS1");
1896 for (s = buf; *s; s++)
1897 if ((*s >= '0' && *s <= '9') || *s == ',')
1899 idx = simple_strtoul(s, NULL, 10);
1902 __add_preferred_console(buf, idx, options, brl_options);
1903 console_set_on_cmdline = 1;
1906 __setup("console=", console_setup);
1909 * add_preferred_console - add a device to the list of preferred consoles.
1910 * @name: device name
1911 * @idx: device index
1912 * @options: options for this console
1914 * The last preferred console added will be used for kernel messages
1915 * and stdin/out/err for init. Normally this is used by console_setup
1916 * above to handle user-supplied console arguments; however it can also
1917 * be used by arch-specific code either to override the user or more
1918 * commonly to provide a default console (ie from PROM variables) when
1919 * the user has not supplied one.
1921 int add_preferred_console(char *name, int idx, char *options)
1923 return __add_preferred_console(name, idx, options, NULL);
1926 int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
1928 struct console_cmdline *c;
1931 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
1932 if (strcmp(console_cmdline[i].name, name) == 0 &&
1933 console_cmdline[i].index == idx) {
1934 c = &console_cmdline[i];
1935 strlcpy(c->name, name_new, sizeof(c->name));
1936 c->name[sizeof(c->name) - 1] = 0;
1937 c->options = options;
1945 bool console_suspend_enabled = 1;
1946 EXPORT_SYMBOL(console_suspend_enabled);
1948 static int __init console_suspend_disable(char *str)
1950 console_suspend_enabled = 0;
1953 __setup("no_console_suspend", console_suspend_disable);
1954 module_param_named(console_suspend, console_suspend_enabled,
1955 bool, S_IRUGO | S_IWUSR);
1956 MODULE_PARM_DESC(console_suspend, "suspend console during suspend"
1957 " and hibernate operations");
1960 * suspend_console - suspend the console subsystem
1962 * This disables printk() while we go into suspend states
1964 void suspend_console(void)
1966 if (!console_suspend_enabled)
1968 printk("Suspending console(s) (use no_console_suspend to debug)\n");
1970 console_suspended = 1;
1974 void resume_console(void)
1976 if (!console_suspend_enabled)
1979 console_suspended = 0;
1984 * console_cpu_notify - print deferred console messages after CPU hotplug
1985 * @self: notifier struct
1986 * @action: CPU hotplug event
1989 * If printk() is called from a CPU that is not online yet, the messages
1990 * will be spooled but will not show up on the console. This function is
1991 * called when a new CPU comes online (or fails to come up), and ensures
1992 * that any such output gets printed.
1994 static int __cpuinit console_cpu_notify(struct notifier_block *self,
1995 unsigned long action, void *hcpu)
2000 case CPU_DOWN_FAILED:
2001 case CPU_UP_CANCELED:
2009 * console_lock - lock the console system for exclusive use.
2011 * Acquires a lock which guarantees that the caller has
2012 * exclusive access to the console system and the console_drivers list.
2014 * Can sleep, returns nothing.
2016 void console_lock(void)
2021 if (console_suspended)
2024 console_may_schedule = 1;
2025 mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
2027 EXPORT_SYMBOL(console_lock);
2030 * console_trylock - try to lock the console system for exclusive use.
2032 * Tried to acquire a lock which guarantees that the caller has
2033 * exclusive access to the console system and the console_drivers list.
2035 * returns 1 on success, and 0 on failure to acquire the lock.
2037 int console_trylock(void)
2039 if (down_trylock(&console_sem))
2041 if (console_suspended) {
2046 console_may_schedule = 0;
2047 mutex_acquire(&console_lock_dep_map, 0, 1, _RET_IP_);
2050 EXPORT_SYMBOL(console_trylock);
2052 int is_console_locked(void)
2054 return console_locked;
2057 static void console_cont_flush(char *text, size_t size)
2059 unsigned long flags;
2062 raw_spin_lock_irqsave(&logbuf_lock, flags);
2068 * We still queue earlier records, likely because the console was
2069 * busy. The earlier ones need to be printed before this one, we
2070 * did not flush any fragment so far, so just let it queue up.
2072 if (console_seq < log_next_seq && !cont.cons)
2075 len = cont_print_text(text, size);
2076 raw_spin_unlock(&logbuf_lock);
2077 stop_critical_timings();
2078 call_console_drivers(cont.level, text, len);
2079 start_critical_timings();
2080 local_irq_restore(flags);
2083 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2087 * console_unlock - unlock the console system
2089 * Releases the console_lock which the caller holds on the console system
2090 * and the console driver list.
2092 * While the console_lock was held, console output may have been buffered
2093 * by printk(). If this is the case, console_unlock(); emits
2094 * the output prior to releasing the lock.
2096 * If there is output waiting, we wake /dev/kmsg and syslog() users.
2098 * console_unlock(); may be called from any context.
2100 void console_unlock(void)
2102 static char text[LOG_LINE_MAX + PREFIX_MAX];
2103 static u64 seen_seq;
2104 unsigned long flags;
2105 bool wake_klogd = false;
2108 if (console_suspended) {
2113 console_may_schedule = 0;
2115 /* flush buffered message fragment immediately to console */
2116 console_cont_flush(text, sizeof(text));
2123 raw_spin_lock_irqsave(&logbuf_lock, flags);
2124 if (seen_seq != log_next_seq) {
2126 seen_seq = log_next_seq;
2129 if (console_seq < log_first_seq) {
2130 /* messages are gone, move to first one */
2131 console_seq = log_first_seq;
2132 console_idx = log_first_idx;
2136 if (console_seq == log_next_seq)
2139 msg = log_from_idx(console_idx);
2140 if (msg->flags & LOG_NOCONS) {
2142 * Skip record we have buffered and already printed
2143 * directly to the console when we received it.
2145 console_idx = log_next(console_idx);
2148 * We will get here again when we register a new
2149 * CON_PRINTBUFFER console. Clear the flag so we
2150 * will properly dump everything later.
2152 msg->flags &= ~LOG_NOCONS;
2153 console_prev = msg->flags;
2158 len = msg_print_text(msg, console_prev, false,
2159 text, sizeof(text));
2160 console_idx = log_next(console_idx);
2162 console_prev = msg->flags;
2163 raw_spin_unlock(&logbuf_lock);
2165 stop_critical_timings(); /* don't trace print latency */
2166 call_console_drivers(level, text, len);
2167 start_critical_timings();
2168 local_irq_restore(flags);
2171 mutex_release(&console_lock_dep_map, 1, _RET_IP_);
2173 /* Release the exclusive_console once it is used */
2174 if (unlikely(exclusive_console))
2175 exclusive_console = NULL;
2177 raw_spin_unlock(&logbuf_lock);
2182 * Someone could have filled up the buffer again, so re-check if there's
2183 * something to flush. In case we cannot trylock the console_sem again,
2184 * there's a new owner and the console_unlock() from them will do the
2185 * flush, no worries.
2187 raw_spin_lock(&logbuf_lock);
2188 retry = console_seq != log_next_seq;
2189 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2191 if (retry && console_trylock())
2197 EXPORT_SYMBOL(console_unlock);
2200 * console_conditional_schedule - yield the CPU if required
2202 * If the console code is currently allowed to sleep, and
2203 * if this CPU should yield the CPU to another task, do
2206 * Must be called within console_lock();.
2208 void __sched console_conditional_schedule(void)
2210 if (console_may_schedule)
2213 EXPORT_SYMBOL(console_conditional_schedule);
2215 void console_unblank(void)
2220 * console_unblank can no longer be called in interrupt context unless
2221 * oops_in_progress is set to 1..
2223 if (oops_in_progress) {
2224 if (down_trylock(&console_sem) != 0)
2230 console_may_schedule = 0;
2232 if ((c->flags & CON_ENABLED) && c->unblank)
2238 * Return the console tty driver structure and its associated index
2240 struct tty_driver *console_device(int *index)
2243 struct tty_driver *driver = NULL;
2246 for_each_console(c) {
2249 driver = c->device(c, index);
2258 * Prevent further output on the passed console device so that (for example)
2259 * serial drivers can disable console output before suspending a port, and can
2260 * re-enable output afterwards.
2262 void console_stop(struct console *console)
2265 console->flags &= ~CON_ENABLED;
2268 EXPORT_SYMBOL(console_stop);
2270 void console_start(struct console *console)
2273 console->flags |= CON_ENABLED;
2276 EXPORT_SYMBOL(console_start);
2278 static int __read_mostly keep_bootcon;
2280 static int __init keep_bootcon_setup(char *str)
2283 printk(KERN_INFO "debug: skip boot console de-registration.\n");
2288 early_param("keep_bootcon", keep_bootcon_setup);
2291 * The console driver calls this routine during kernel initialization
2292 * to register the console printing procedure with printk() and to
2293 * print any messages that were printed by the kernel before the
2294 * console driver was initialized.
2296 * This can happen pretty early during the boot process (because of
2297 * early_printk) - sometimes before setup_arch() completes - be careful
2298 * of what kernel features are used - they may not be initialised yet.
2300 * There are two types of consoles - bootconsoles (early_printk) and
2301 * "real" consoles (everything which is not a bootconsole) which are
2302 * handled differently.
2303 * - Any number of bootconsoles can be registered at any time.
2304 * - As soon as a "real" console is registered, all bootconsoles
2305 * will be unregistered automatically.
2306 * - Once a "real" console is registered, any attempt to register a
2307 * bootconsoles will be rejected
2309 void register_console(struct console *newcon)
2312 unsigned long flags;
2313 struct console *bcon = NULL;
2316 * before we register a new CON_BOOT console, make sure we don't
2317 * already have a valid console
2319 if (console_drivers && newcon->flags & CON_BOOT) {
2320 /* find the last or real console */
2321 for_each_console(bcon) {
2322 if (!(bcon->flags & CON_BOOT)) {
2323 printk(KERN_INFO "Too late to register bootconsole %s%d\n",
2324 newcon->name, newcon->index);
2330 if (console_drivers && console_drivers->flags & CON_BOOT)
2331 bcon = console_drivers;
2333 if (preferred_console < 0 || bcon || !console_drivers)
2334 preferred_console = selected_console;
2336 if (newcon->early_setup)
2337 newcon->early_setup();
2340 * See if we want to use this console driver. If we
2341 * didn't select a console we take the first one
2342 * that registers here.
2344 if (preferred_console < 0) {
2345 if (newcon->index < 0)
2347 if (newcon->setup == NULL ||
2348 newcon->setup(newcon, NULL) == 0) {
2349 newcon->flags |= CON_ENABLED;
2350 if (newcon->device) {
2351 newcon->flags |= CON_CONSDEV;
2352 preferred_console = 0;
2358 * See if this console matches one we selected on
2361 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
2363 BUILD_BUG_ON(sizeof(console_cmdline[i].name) !=
2364 sizeof(newcon->name));
2365 if (strcmp(console_cmdline[i].name, newcon->name) != 0)
2367 if (newcon->index >= 0 &&
2368 newcon->index != console_cmdline[i].index)
2370 if (newcon->index < 0)
2371 newcon->index = console_cmdline[i].index;
2372 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
2373 if (console_cmdline[i].brl_options) {
2374 newcon->flags |= CON_BRL;
2375 braille_register_console(newcon,
2376 console_cmdline[i].index,
2377 console_cmdline[i].options,
2378 console_cmdline[i].brl_options);
2382 if (newcon->setup &&
2383 newcon->setup(newcon, console_cmdline[i].options) != 0)
2385 newcon->flags |= CON_ENABLED;
2386 newcon->index = console_cmdline[i].index;
2387 if (i == selected_console) {
2388 newcon->flags |= CON_CONSDEV;
2389 preferred_console = selected_console;
2394 if (!(newcon->flags & CON_ENABLED))
2398 * If we have a bootconsole, and are switching to a real console,
2399 * don't print everything out again, since when the boot console, and
2400 * the real console are the same physical device, it's annoying to
2401 * see the beginning boot messages twice
2403 if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
2404 newcon->flags &= ~CON_PRINTBUFFER;
2407 * Put this console in the list - keep the
2408 * preferred driver at the head of the list.
2411 if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
2412 newcon->next = console_drivers;
2413 console_drivers = newcon;
2415 newcon->next->flags &= ~CON_CONSDEV;
2417 newcon->next = console_drivers->next;
2418 console_drivers->next = newcon;
2420 if (newcon->flags & CON_PRINTBUFFER) {
2422 * console_unlock(); will print out the buffered messages
2425 raw_spin_lock_irqsave(&logbuf_lock, flags);
2426 console_seq = syslog_seq;
2427 console_idx = syslog_idx;
2428 console_prev = syslog_prev;
2429 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2431 * We're about to replay the log buffer. Only do this to the
2432 * just-registered console to avoid excessive message spam to
2433 * the already-registered consoles.
2435 exclusive_console = newcon;
2438 console_sysfs_notify();
2441 * By unregistering the bootconsoles after we enable the real console
2442 * we get the "console xxx enabled" message on all the consoles -
2443 * boot consoles, real consoles, etc - this is to ensure that end
2444 * users know there might be something in the kernel's log buffer that
2445 * went to the bootconsole (that they do not see on the real console)
2448 ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
2450 /* we need to iterate through twice, to make sure we print
2451 * everything out, before we unregister the console(s)
2453 printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n",
2454 newcon->name, newcon->index);
2455 for_each_console(bcon)
2456 if (bcon->flags & CON_BOOT)
2457 unregister_console(bcon);
2459 printk(KERN_INFO "%sconsole [%s%d] enabled\n",
2460 (newcon->flags & CON_BOOT) ? "boot" : "" ,
2461 newcon->name, newcon->index);
2464 EXPORT_SYMBOL(register_console);
2466 int unregister_console(struct console *console)
2468 struct console *a, *b;
2471 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
2472 if (console->flags & CON_BRL)
2473 return braille_unregister_console(console);
2477 if (console_drivers == console) {
2478 console_drivers=console->next;
2480 } else if (console_drivers) {
2481 for (a=console_drivers->next, b=console_drivers ;
2482 a; b=a, a=b->next) {
2492 * If this isn't the last console and it has CON_CONSDEV set, we
2493 * need to set it on the next preferred console.
2495 if (console_drivers != NULL && console->flags & CON_CONSDEV)
2496 console_drivers->flags |= CON_CONSDEV;
2499 console_sysfs_notify();
2502 EXPORT_SYMBOL(unregister_console);
2504 static int __init printk_late_init(void)
2506 struct console *con;
2508 for_each_console(con) {
2509 if (!keep_bootcon && con->flags & CON_BOOT) {
2510 printk(KERN_INFO "turn off boot console %s%d\n",
2511 con->name, con->index);
2512 unregister_console(con);
2515 hotcpu_notifier(console_cpu_notify, 0);
2518 late_initcall(printk_late_init);
2520 #if defined CONFIG_PRINTK
2522 * Delayed printk version, for scheduler-internal messages:
2524 #define PRINTK_BUF_SIZE 512
2526 #define PRINTK_PENDING_WAKEUP 0x01
2527 #define PRINTK_PENDING_SCHED 0x02
2529 static DEFINE_PER_CPU(int, printk_pending);
2530 static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
2532 static void wake_up_klogd_work_func(struct irq_work *irq_work)
2534 int pending = __this_cpu_xchg(printk_pending, 0);
2536 if (pending & PRINTK_PENDING_SCHED) {
2537 char *buf = __get_cpu_var(printk_sched_buf);
2538 printk(KERN_WARNING "[sched_delayed] %s", buf);
2541 if (pending & PRINTK_PENDING_WAKEUP)
2542 wake_up_interruptible(&log_wait);
2545 static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
2546 .func = wake_up_klogd_work_func,
2547 .flags = IRQ_WORK_LAZY,
2550 void wake_up_klogd(void)
2553 if (waitqueue_active(&log_wait)) {
2554 this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
2555 irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
2560 int printk_deferred(const char *fmt, ...)
2562 unsigned long flags;
2567 local_irq_save(flags);
2568 buf = __get_cpu_var(printk_sched_buf);
2570 va_start(args, fmt);
2571 r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
2574 __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
2575 irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
2576 local_irq_restore(flags);
2582 * printk rate limiting, lifted from the networking subsystem.
2584 * This enforces a rate limit: not more than 10 kernel messages
2585 * every 5s to make a denial-of-service attack impossible.
2587 DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
2589 int __printk_ratelimit(const char *func)
2591 return ___ratelimit(&printk_ratelimit_state, func);
2593 EXPORT_SYMBOL(__printk_ratelimit);
2596 * printk_timed_ratelimit - caller-controlled printk ratelimiting
2597 * @caller_jiffies: pointer to caller's state
2598 * @interval_msecs: minimum interval between prints
2600 * printk_timed_ratelimit() returns true if more than @interval_msecs
2601 * milliseconds have elapsed since the last time printk_timed_ratelimit()
2604 bool printk_timed_ratelimit(unsigned long *caller_jiffies,
2605 unsigned int interval_msecs)
2607 if (*caller_jiffies == 0
2608 || !time_in_range(jiffies, *caller_jiffies,
2610 + msecs_to_jiffies(interval_msecs))) {
2611 *caller_jiffies = jiffies;
2616 EXPORT_SYMBOL(printk_timed_ratelimit);
2618 static DEFINE_SPINLOCK(dump_list_lock);
2619 static LIST_HEAD(dump_list);
2622 * kmsg_dump_register - register a kernel log dumper.
2623 * @dumper: pointer to the kmsg_dumper structure
2625 * Adds a kernel log dumper to the system. The dump callback in the
2626 * structure will be called when the kernel oopses or panics and must be
2627 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
2629 int kmsg_dump_register(struct kmsg_dumper *dumper)
2631 unsigned long flags;
2634 /* The dump callback needs to be set */
2638 spin_lock_irqsave(&dump_list_lock, flags);
2639 /* Don't allow registering multiple times */
2640 if (!dumper->registered) {
2641 dumper->registered = 1;
2642 list_add_tail_rcu(&dumper->list, &dump_list);
2645 spin_unlock_irqrestore(&dump_list_lock, flags);
2649 EXPORT_SYMBOL_GPL(kmsg_dump_register);
2652 * kmsg_dump_unregister - unregister a kmsg dumper.
2653 * @dumper: pointer to the kmsg_dumper structure
2655 * Removes a dump device from the system. Returns zero on success and
2656 * %-EINVAL otherwise.
2658 int kmsg_dump_unregister(struct kmsg_dumper *dumper)
2660 unsigned long flags;
2663 spin_lock_irqsave(&dump_list_lock, flags);
2664 if (dumper->registered) {
2665 dumper->registered = 0;
2666 list_del_rcu(&dumper->list);
2669 spin_unlock_irqrestore(&dump_list_lock, flags);
2674 EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
2676 static bool always_kmsg_dump;
2677 module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
2680 * kmsg_dump - dump kernel log to kernel message dumpers.
2681 * @reason: the reason (oops, panic etc) for dumping
2683 * Call each of the registered dumper's dump() callback, which can
2684 * retrieve the kmsg records with kmsg_dump_get_line() or
2685 * kmsg_dump_get_buffer().
2687 void kmsg_dump(enum kmsg_dump_reason reason)
2689 struct kmsg_dumper *dumper;
2690 unsigned long flags;
2692 if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
2696 list_for_each_entry_rcu(dumper, &dump_list, list) {
2697 if (dumper->max_reason && reason > dumper->max_reason)
2700 /* initialize iterator with data about the stored records */
2701 dumper->active = true;
2703 raw_spin_lock_irqsave(&logbuf_lock, flags);
2704 dumper->cur_seq = clear_seq;
2705 dumper->cur_idx = clear_idx;
2706 dumper->next_seq = log_next_seq;
2707 dumper->next_idx = log_next_idx;
2708 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2710 /* invoke dumper which will iterate over records */
2711 dumper->dump(dumper, reason);
2713 /* reset iterator */
2714 dumper->active = false;
2720 * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
2721 * @dumper: registered kmsg dumper
2722 * @syslog: include the "<4>" prefixes
2723 * @line: buffer to copy the line to
2724 * @size: maximum size of the buffer
2725 * @len: length of line placed into buffer
2727 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2728 * record, and copy one record into the provided buffer.
2730 * Consecutive calls will return the next available record moving
2731 * towards the end of the buffer with the youngest messages.
2733 * A return value of FALSE indicates that there are no more records to
2736 * The function is similar to kmsg_dump_get_line(), but grabs no locks.
2738 bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
2739 char *line, size_t size, size_t *len)
2745 if (!dumper->active)
2748 if (dumper->cur_seq < log_first_seq) {
2749 /* messages are gone, move to first available one */
2750 dumper->cur_seq = log_first_seq;
2751 dumper->cur_idx = log_first_idx;
2755 if (dumper->cur_seq >= log_next_seq)
2758 msg = log_from_idx(dumper->cur_idx);
2759 l = msg_print_text(msg, 0, syslog, line, size);
2761 dumper->cur_idx = log_next(dumper->cur_idx);
2771 * kmsg_dump_get_line - retrieve one kmsg log line
2772 * @dumper: registered kmsg dumper
2773 * @syslog: include the "<4>" prefixes
2774 * @line: buffer to copy the line to
2775 * @size: maximum size of the buffer
2776 * @len: length of line placed into buffer
2778 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2779 * record, and copy one record into the provided buffer.
2781 * Consecutive calls will return the next available record moving
2782 * towards the end of the buffer with the youngest messages.
2784 * A return value of FALSE indicates that there are no more records to
2787 bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
2788 char *line, size_t size, size_t *len)
2790 unsigned long flags;
2793 raw_spin_lock_irqsave(&logbuf_lock, flags);
2794 ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
2795 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2799 EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
2802 * kmsg_dump_get_buffer - copy kmsg log lines
2803 * @dumper: registered kmsg dumper
2804 * @syslog: include the "<4>" prefixes
2805 * @buf: buffer to copy the line to
2806 * @size: maximum size of the buffer
2807 * @len: length of line placed into buffer
2809 * Start at the end of the kmsg buffer and fill the provided buffer
2810 * with as many of the the *youngest* kmsg records that fit into it.
2811 * If the buffer is large enough, all available kmsg records will be
2812 * copied with a single call.
2814 * Consecutive calls will fill the buffer with the next block of
2815 * available older records, not including the earlier retrieved ones.
2817 * A return value of FALSE indicates that there are no more records to
2820 bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
2821 char *buf, size_t size, size_t *len)
2823 unsigned long flags;
2828 enum log_flags prev;
2832 if (!dumper->active)
2835 raw_spin_lock_irqsave(&logbuf_lock, flags);
2836 if (dumper->cur_seq < log_first_seq) {
2837 /* messages are gone, move to first available one */
2838 dumper->cur_seq = log_first_seq;
2839 dumper->cur_idx = log_first_idx;
2843 if (dumper->cur_seq >= dumper->next_seq) {
2844 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2848 /* calculate length of entire buffer */
2849 seq = dumper->cur_seq;
2850 idx = dumper->cur_idx;
2852 while (seq < dumper->next_seq) {
2853 struct log *msg = log_from_idx(idx);
2855 l += msg_print_text(msg, prev, true, NULL, 0);
2856 idx = log_next(idx);
2861 /* move first record forward until length fits into the buffer */
2862 seq = dumper->cur_seq;
2863 idx = dumper->cur_idx;
2865 while (l > size && seq < dumper->next_seq) {
2866 struct log *msg = log_from_idx(idx);
2868 l -= msg_print_text(msg, prev, true, NULL, 0);
2869 idx = log_next(idx);
2874 /* last message in next interation */
2880 while (seq < dumper->next_seq) {
2881 struct log *msg = log_from_idx(idx);
2883 l += msg_print_text(msg, prev, syslog, buf + l, size - l);
2884 idx = log_next(idx);
2889 dumper->next_seq = next_seq;
2890 dumper->next_idx = next_idx;
2892 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2898 EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
2901 * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
2902 * @dumper: registered kmsg dumper
2904 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2905 * kmsg_dump_get_buffer() can be called again and used multiple
2906 * times within the same dumper.dump() callback.
2908 * The function is similar to kmsg_dump_rewind(), but grabs no locks.
2910 void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
2912 dumper->cur_seq = clear_seq;
2913 dumper->cur_idx = clear_idx;
2914 dumper->next_seq = log_next_seq;
2915 dumper->next_idx = log_next_idx;
2919 * kmsg_dump_rewind - reset the interator
2920 * @dumper: registered kmsg dumper
2922 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2923 * kmsg_dump_get_buffer() can be called again and used multiple
2924 * times within the same dumper.dump() callback.
2926 void kmsg_dump_rewind(struct kmsg_dumper *dumper)
2928 unsigned long flags;
2930 raw_spin_lock_irqsave(&logbuf_lock, flags);
2931 kmsg_dump_rewind_nolock(dumper);
2932 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2934 EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
2936 static char dump_stack_arch_desc_str[128];
2939 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
2940 * @fmt: printf-style format string
2941 * @...: arguments for the format string
2943 * The configured string will be printed right after utsname during task
2944 * dumps. Usually used to add arch-specific system identifiers. If an
2945 * arch wants to make use of such an ID string, it should initialize this
2946 * as soon as possible during boot.
2948 void __init dump_stack_set_arch_desc(const char *fmt, ...)
2952 va_start(args, fmt);
2953 vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
2959 * dump_stack_print_info - print generic debug info for dump_stack()
2960 * @log_lvl: log level
2962 * Arch-specific dump_stack() implementations can use this function to
2963 * print out the same debug information as the generic dump_stack().
2965 void dump_stack_print_info(const char *log_lvl)
2967 printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
2968 log_lvl, raw_smp_processor_id(), current->pid, current->comm,
2969 print_tainted(), init_utsname()->release,
2970 (int)strcspn(init_utsname()->version, " "),
2971 init_utsname()->version);
2973 if (dump_stack_arch_desc_str[0] != '\0')
2974 printk("%sHardware name: %s\n",
2975 log_lvl, dump_stack_arch_desc_str);
2977 print_worker_info(log_lvl, current);
2981 * show_regs_print_info - print generic debug info for show_regs()
2982 * @log_lvl: log level
2984 * show_regs() implementations can use this function to print out generic
2985 * debug information.
2987 void show_regs_print_info(const char *log_lvl)
2989 dump_stack_print_info(log_lvl);
2991 printk("%stask: %p ti: %p task.ti: %p\n",
2992 log_lvl, current, current_thread_info(),
2993 task_thread_info(current));