blob: ac4bc9e79465ed6cf416d9694f8ddc463e2e77ab [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/kernel/printk.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
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).
11 * Ted Ts'o, 2/11/93.
12 * Modified for sysctl support, 1/8/97, Chris Horn.
Jesper Juhl40dc5652005-10-30 15:02:46 -080013 * Fixed SMP synchronization, 08/08/99, Manfred Spraul
Christian Kujau624dffc2006-01-15 02:43:54 +010014 * manfred@colorfullife.com
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 * Rewrote bits to get rid of console_lock
Francois Camie1f8e872008-10-15 22:01:59 -070016 * 01Mar01 Andrew Morton
Linus Torvalds1da177e2005-04-16 15:20:36 -070017 */
18
19#include <linux/kernel.h>
20#include <linux/mm.h>
21#include <linux/tty.h>
22#include <linux/tty_driver.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <linux/console.h>
24#include <linux/init.h>
Randy Dunlapbfe8df32007-10-16 01:23:46 -070025#include <linux/jiffies.h>
26#include <linux/nmi.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/module.h>
Jan Engelhardt3b9c0412006-06-25 05:48:15 -070028#include <linux/moduleparam.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/interrupt.h> /* For in_interrupt() */
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include <linux/delay.h>
31#include <linux/smp.h>
32#include <linux/security.h>
33#include <linux/bootmem.h>
Mike Travis162a7e72011-05-24 17:13:20 -070034#include <linux/memblock.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <linux/syscalls.h>
Neil Horman04d491a2009-04-02 16:58:57 -070036#include <linux/kexec.h>
Jason Wesseld37d39a2010-05-20 21:04:27 -050037#include <linux/kdb.h>
Ingo Molnar3fff4c42009-09-22 16:18:09 +020038#include <linux/ratelimit.h>
Simon Kagstrom456b5652009-10-16 14:09:18 +020039#include <linux/kmsg_dump.h>
Kees Cook00234592010-02-03 15:36:43 -080040#include <linux/syslog.h>
Kevin Cernekee034260d2010-06-03 22:11:25 -070041#include <linux/cpu.h>
42#include <linux/notifier.h>
Huang Yingfb842b02011-01-12 16:59:43 -080043#include <linux/rculist.h>
Kay Sieverse11fea92012-05-03 02:29:41 +020044#include <linux/poll.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
46#include <asm/uaccess.h>
47
Johannes Berg95100352011-11-24 20:03:08 +010048#define CREATE_TRACE_POINTS
49#include <trace/events/printk.h>
50
Ingo Molnar076f9772008-01-30 13:33:06 +010051/*
52 * Architectures can override it:
53 */
Jiri Slabye17ba732008-05-12 15:44:40 +020054void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...)
Ingo Molnar076f9772008-01-30 13:33:06 +010055{
56}
57
Linus Torvalds1da177e2005-04-16 15:20:36 -070058/* printk's without a loglevel use this.. */
Mandeep Singh Baines5af5bcb2011-03-22 16:34:23 -070059#define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
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 */
64
65DECLARE_WAIT_QUEUE_HEAD(log_wait);
66
67int console_printk[4] = {
68 DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
69 DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
70 MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */
71 DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
72};
73
Linus Torvalds1da177e2005-04-16 15:20:36 -070074/*
Patrick Pletscher0bbfb7c2007-02-17 20:10:16 +010075 * Low level drivers may need that to know if they can schedule in
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 * their unblank() callback or not. So let's export it.
77 */
78int oops_in_progress;
79EXPORT_SYMBOL(oops_in_progress);
80
81/*
82 * console_sem protects the console_drivers list, and also
83 * provides serialisation for access to the entire console
84 * driver system.
85 */
Thomas Gleixner5b8c4f22010-09-07 14:33:43 +000086static DEFINE_SEMAPHORE(console_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -070087struct console *console_drivers;
Ingo Molnara29d1cf2008-06-02 13:19:08 +020088EXPORT_SYMBOL_GPL(console_drivers);
89
Linus Torvalds1da177e2005-04-16 15:20:36 -070090/*
91 * This is used for debugging the mess that is the VT code by
92 * keeping track if we have the console semaphore held. It's
93 * definitely not the perfect debug tool (we don't know if _WE_
94 * hold it are racing, but it helps tracking those weird code
95 * path in the console code where we end up in places I want
96 * locked without the console sempahore held
97 */
Linus Torvalds557240b2006-06-19 18:16:01 -070098static int console_locked, console_suspended;
Linus Torvalds1da177e2005-04-16 15:20:36 -070099
100/*
Feng Tangfe3d8ad2011-03-22 16:34:21 -0700101 * If exclusive_console is non-NULL then only this console is to be printed to.
102 */
103static struct console *exclusive_console;
104
105/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 * Array of consoles built from command line options (console=)
107 */
108struct console_cmdline
109{
110 char name[8]; /* Name of the driver */
111 int index; /* Minor dev. to use */
112 char *options; /* Options for the driver */
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700113#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
114 char *brl_options; /* Options for braille driver */
115#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116};
117
118#define MAX_CMDLINECONSOLES 8
119
120static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
121static int selected_console = -1;
122static int preferred_console = -1;
Markus Armbruster9e124fe2008-05-26 23:31:07 +0100123int console_set_on_cmdline;
124EXPORT_SYMBOL(console_set_on_cmdline);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125
126/* Flag: console code may call schedule() */
127static int console_may_schedule;
128
Kay Sievers7ff95542012-05-03 02:29:13 +0200129/*
130 * The printk log buffer consists of a chain of concatenated variable
131 * length records. Every record starts with a record header, containing
132 * the overall length of the record.
133 *
134 * The heads to the first and last entry in the buffer, as well as the
135 * sequence numbers of these both entries are maintained when messages
136 * are stored..
137 *
138 * If the heads indicate available messages, the length in the header
139 * tells the start next message. A length == 0 for the next message
140 * indicates a wrap-around to the beginning of the buffer.
141 *
142 * Every record carries the monotonic timestamp in microseconds, as well as
143 * the standard userspace syslog level and syslog facility. The usual
144 * kernel messages use LOG_KERN; userspace-injected messages always carry
145 * a matching syslog facility, by default LOG_USER. The origin of every
146 * message can be reliably determined that way.
147 *
148 * The human readable log message directly follows the message header. The
149 * length of the message text is stored in the header, the stored message
150 * is not terminated.
151 *
Kay Sieverse11fea92012-05-03 02:29:41 +0200152 * Optionally, a message can carry a dictionary of properties (key/value pairs),
153 * to provide userspace with a machine-readable message context.
154 *
155 * Examples for well-defined, commonly used property names are:
156 * DEVICE=b12:8 device identifier
157 * b12:8 block dev_t
158 * c127:3 char dev_t
159 * n8 netdev ifindex
160 * +sound:card0 subsystem:devname
161 * SUBSYSTEM=pci driver-core subsystem name
162 *
163 * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
164 * follows directly after a '=' character. Every property is terminated by
165 * a '\0' character. The last property is not terminated.
166 *
167 * Example of a message structure:
168 * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec
169 * 0008 34 00 record is 52 bytes long
170 * 000a 0b 00 text is 11 bytes long
171 * 000c 1f 00 dictionary is 23 bytes long
172 * 000e 03 00 LOG_KERN (facility) LOG_ERR (level)
173 * 0010 69 74 27 73 20 61 20 6c "it's a l"
174 * 69 6e 65 "ine"
175 * 001b 44 45 56 49 43 "DEVIC"
176 * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D"
177 * 52 49 56 45 52 3d 62 75 "RIVER=bu"
178 * 67 "g"
179 * 0032 00 00 00 padding to next message header
180 *
181 * The 'struct log' buffer header must never be directly exported to
182 * userspace, it is a kernel-private implementation detail that might
183 * need to be changed in the future, when the requirements change.
184 *
185 * /dev/kmsg exports the structured data in the following line format:
186 * "level,sequnum,timestamp;<message text>\n"
187 *
188 * The optional key/value pairs are attached as continuation lines starting
189 * with a space character and terminated by a newline. All possible
190 * non-prinatable characters are escaped in the "\xff" notation.
191 *
192 * Users of the export format should ignore possible additional values
193 * separated by ',', and find the message after the ';' character.
Kay Sievers7ff95542012-05-03 02:29:13 +0200194 */
Matt Mackalld59745c2005-05-01 08:59:02 -0700195
Kay Sievers084681d2012-06-28 09:38:53 +0200196enum log_flags {
Kay Sievers5becfb12012-07-09 12:15:42 -0700197 LOG_NOCONS = 1, /* already flushed, do not print to console */
198 LOG_NEWLINE = 2, /* text ended with a newline */
199 LOG_PREFIX = 4, /* text started with a prefix */
200 LOG_CONT = 8, /* text is a fragment of a continuation line */
Kay Sievers084681d2012-06-28 09:38:53 +0200201};
202
Kay Sievers7ff95542012-05-03 02:29:13 +0200203struct log {
204 u64 ts_nsec; /* timestamp in nanoseconds */
205 u16 len; /* length of entire record */
206 u16 text_len; /* length of text buffer */
207 u16 dict_len; /* length of dictionary buffer */
Kay Sievers084681d2012-06-28 09:38:53 +0200208 u8 facility; /* syslog facility */
209 u8 flags:5; /* internal record flags */
210 u8 level:3; /* syslog level */
Kay Sievers7ff95542012-05-03 02:29:13 +0200211};
212
213/*
214 * The logbuf_lock protects kmsg buffer, indices, counters. It is also
215 * used in interesting ways to provide interlocking in console_unlock();
216 */
217static DEFINE_RAW_SPINLOCK(logbuf_lock);
218
Kay Sievers7f3a7812012-05-09 01:37:51 +0200219/* the next printk record to read by syslog(READ) or /proc/kmsg */
220static u64 syslog_seq;
221static u32 syslog_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -0700222static enum log_flags syslog_prev;
Kay Sieverseb02dac2012-07-09 10:05:10 -0700223static size_t syslog_partial;
Kay Sievers7f3a7812012-05-09 01:37:51 +0200224
225/* index and sequence number of the first record stored in the buffer */
226static u64 log_first_seq;
227static u32 log_first_idx;
228
229/* index and sequence number of the next record to store in the buffer */
230static u64 log_next_seq;
231#ifdef CONFIG_PRINTK
232static u32 log_next_idx;
233
234/* the next printk record to read after the last 'clear' command */
235static u64 clear_seq;
236static u32 clear_idx;
Kay Sievers7ff95542012-05-03 02:29:13 +0200237
238#define LOG_LINE_MAX 1024
239
240/* record buffer */
Andrew Lunn6ebb0172012-06-05 08:52:34 +0200241#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
Stephen Warrenf8450fc2012-05-10 16:14:33 -0600242#define LOG_ALIGN 4
243#else
Andrew Lunn6ebb0172012-06-05 08:52:34 +0200244#define LOG_ALIGN __alignof__(struct log)
Stephen Warrenf8450fc2012-05-10 16:14:33 -0600245#endif
Kay Sievers7ff95542012-05-03 02:29:13 +0200246#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
Stephen Warrenf8450fc2012-05-10 16:14:33 -0600247static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
Matt Mackalld59745c2005-05-01 08:59:02 -0700248static char *log_buf = __log_buf;
Kay Sievers7ff95542012-05-03 02:29:13 +0200249static u32 log_buf_len = __LOG_BUF_LEN;
250
Kay Sievers7f3a7812012-05-09 01:37:51 +0200251/* cpu currently holding logbuf_lock */
252static volatile unsigned int logbuf_cpu = UINT_MAX;
Kay Sievers7ff95542012-05-03 02:29:13 +0200253
254/* human readable text of the record */
255static char *log_text(const struct log *msg)
256{
257 return (char *)msg + sizeof(struct log);
258}
259
260/* optional key/value pair dictionary attached to the record */
261static char *log_dict(const struct log *msg)
262{
263 return (char *)msg + sizeof(struct log) + msg->text_len;
264}
265
266/* get record by index; idx must point to valid msg */
267static struct log *log_from_idx(u32 idx)
268{
269 struct log *msg = (struct log *)(log_buf + idx);
270
271 /*
272 * A length == 0 record is the end of buffer marker. Wrap around and
273 * read the message at the start of the buffer.
274 */
275 if (!msg->len)
276 return (struct log *)log_buf;
277 return msg;
278}
279
280/* get next record; idx must point to valid msg */
281static u32 log_next(u32 idx)
282{
283 struct log *msg = (struct log *)(log_buf + idx);
284
285 /* length == 0 indicates the end of the buffer; wrap */
286 /*
287 * A length == 0 record is the end of buffer marker. Wrap around and
288 * read the message at the start of the buffer as *this* one, and
289 * return the one after that.
290 */
291 if (!msg->len) {
292 msg = (struct log *)log_buf;
293 return msg->len;
294 }
295 return idx + msg->len;
296}
297
Kay Sievers7ff95542012-05-03 02:29:13 +0200298/* insert record into the buffer, discard old ones, update heads */
299static void log_store(int facility, int level,
Kay Sievers084681d2012-06-28 09:38:53 +0200300 enum log_flags flags, u64 ts_nsec,
Kay Sievers7ff95542012-05-03 02:29:13 +0200301 const char *dict, u16 dict_len,
302 const char *text, u16 text_len)
303{
304 struct log *msg;
305 u32 size, pad_len;
306
307 /* number of '\0' padding bytes to next message */
308 size = sizeof(struct log) + text_len + dict_len;
309 pad_len = (-size) & (LOG_ALIGN - 1);
310 size += pad_len;
311
312 while (log_first_seq < log_next_seq) {
313 u32 free;
314
315 if (log_next_idx > log_first_idx)
316 free = max(log_buf_len - log_next_idx, log_first_idx);
317 else
318 free = log_first_idx - log_next_idx;
319
320 if (free > size + sizeof(struct log))
321 break;
322
323 /* drop old messages until we have enough contiuous space */
324 log_first_idx = log_next(log_first_idx);
325 log_first_seq++;
326 }
327
328 if (log_next_idx + size + sizeof(struct log) >= log_buf_len) {
329 /*
330 * This message + an additional empty header does not fit
331 * at the end of the buffer. Add an empty header with len == 0
332 * to signify a wrap around.
333 */
334 memset(log_buf + log_next_idx, 0, sizeof(struct log));
335 log_next_idx = 0;
336 }
337
338 /* fill message */
339 msg = (struct log *)(log_buf + log_next_idx);
340 memcpy(log_text(msg), text, text_len);
341 msg->text_len = text_len;
342 memcpy(log_dict(msg), dict, dict_len);
343 msg->dict_len = dict_len;
Kay Sievers084681d2012-06-28 09:38:53 +0200344 msg->facility = facility;
345 msg->level = level & 7;
346 msg->flags = flags & 0x1f;
347 if (ts_nsec > 0)
348 msg->ts_nsec = ts_nsec;
349 else
350 msg->ts_nsec = local_clock();
Kay Sievers7ff95542012-05-03 02:29:13 +0200351 memset(log_dict(msg) + dict_len, 0, pad_len);
352 msg->len = sizeof(struct log) + text_len + dict_len + pad_len;
353
354 /* insert message */
355 log_next_idx += msg->len;
356 log_next_seq++;
357}
Matt Mackalld59745c2005-05-01 08:59:02 -0700358
Kay Sieverse11fea92012-05-03 02:29:41 +0200359/* /dev/kmsg - userspace message inject/listen interface */
360struct devkmsg_user {
361 u64 seq;
362 u32 idx;
363 struct mutex lock;
364 char buf[8192];
365};
366
367static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
368 unsigned long count, loff_t pos)
369{
370 char *buf, *line;
371 int i;
372 int level = default_message_loglevel;
373 int facility = 1; /* LOG_USER */
374 size_t len = iov_length(iv, count);
375 ssize_t ret = len;
376
377 if (len > LOG_LINE_MAX)
378 return -EINVAL;
379 buf = kmalloc(len+1, GFP_KERNEL);
380 if (buf == NULL)
381 return -ENOMEM;
382
383 line = buf;
384 for (i = 0; i < count; i++) {
385 if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len))
386 goto out;
387 line += iv[i].iov_len;
388 }
389
390 /*
391 * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
392 * the decimal value represents 32bit, the lower 3 bit are the log
393 * level, the rest are the log facility.
394 *
395 * If no prefix or no userspace facility is specified, we
396 * enforce LOG_USER, to be able to reliably distinguish
397 * kernel-generated messages from userspace-injected ones.
398 */
399 line = buf;
400 if (line[0] == '<') {
401 char *endp = NULL;
402
403 i = simple_strtoul(line+1, &endp, 10);
404 if (endp && endp[0] == '>') {
405 level = i & 7;
406 if (i >> 3)
407 facility = i >> 3;
408 endp++;
409 len -= endp - line;
410 line = endp;
411 }
412 }
413 line[len] = '\0';
414
415 printk_emit(facility, level, NULL, 0, "%s", line);
416out:
417 kfree(buf);
418 return ret;
419}
420
421static ssize_t devkmsg_read(struct file *file, char __user *buf,
422 size_t count, loff_t *ppos)
423{
424 struct devkmsg_user *user = file->private_data;
425 struct log *msg;
Kay Sievers5fc324902012-05-08 13:04:17 +0200426 u64 ts_usec;
Kay Sieverse11fea92012-05-03 02:29:41 +0200427 size_t i;
428 size_t len;
429 ssize_t ret;
430
431 if (!user)
432 return -EBADF;
433
Yuanhan Liu4a77a5a2012-06-16 21:21:51 +0800434 ret = mutex_lock_interruptible(&user->lock);
435 if (ret)
436 return ret;
liu chuansheng5c53d812012-07-06 09:50:08 -0700437 raw_spin_lock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200438 while (user->seq == log_next_seq) {
439 if (file->f_flags & O_NONBLOCK) {
440 ret = -EAGAIN;
liu chuansheng5c53d812012-07-06 09:50:08 -0700441 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200442 goto out;
443 }
444
liu chuansheng5c53d812012-07-06 09:50:08 -0700445 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200446 ret = wait_event_interruptible(log_wait,
447 user->seq != log_next_seq);
448 if (ret)
449 goto out;
liu chuansheng5c53d812012-07-06 09:50:08 -0700450 raw_spin_lock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200451 }
452
453 if (user->seq < log_first_seq) {
454 /* our last seen message is gone, return error and reset */
455 user->idx = log_first_idx;
456 user->seq = log_first_seq;
457 ret = -EPIPE;
liu chuansheng5c53d812012-07-06 09:50:08 -0700458 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200459 goto out;
460 }
461
462 msg = log_from_idx(user->idx);
Kay Sievers5fc324902012-05-08 13:04:17 +0200463 ts_usec = msg->ts_nsec;
464 do_div(ts_usec, 1000);
Kay Sieverse11fea92012-05-03 02:29:41 +0200465 len = sprintf(user->buf, "%u,%llu,%llu;",
Kay Sievers084681d2012-06-28 09:38:53 +0200466 (msg->facility << 3) | msg->level, user->seq, ts_usec);
Kay Sieverse11fea92012-05-03 02:29:41 +0200467
468 /* escape non-printable characters */
469 for (i = 0; i < msg->text_len; i++) {
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200470 unsigned char c = log_text(msg)[i];
Kay Sieverse11fea92012-05-03 02:29:41 +0200471
Kay Sieverse3f5a5f2012-07-06 09:50:09 -0700472 if (c < ' ' || c >= 127 || c == '\\')
Kay Sieverse11fea92012-05-03 02:29:41 +0200473 len += sprintf(user->buf + len, "\\x%02x", c);
474 else
475 user->buf[len++] = c;
476 }
477 user->buf[len++] = '\n';
478
479 if (msg->dict_len) {
480 bool line = true;
481
482 for (i = 0; i < msg->dict_len; i++) {
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200483 unsigned char c = log_dict(msg)[i];
Kay Sieverse11fea92012-05-03 02:29:41 +0200484
485 if (line) {
486 user->buf[len++] = ' ';
487 line = false;
488 }
489
490 if (c == '\0') {
491 user->buf[len++] = '\n';
492 line = true;
493 continue;
494 }
495
Kay Sieverse3f5a5f2012-07-06 09:50:09 -0700496 if (c < ' ' || c >= 127 || c == '\\') {
Kay Sieverse11fea92012-05-03 02:29:41 +0200497 len += sprintf(user->buf + len, "\\x%02x", c);
498 continue;
499 }
500
501 user->buf[len++] = c;
502 }
503 user->buf[len++] = '\n';
504 }
505
506 user->idx = log_next(user->idx);
507 user->seq++;
liu chuansheng5c53d812012-07-06 09:50:08 -0700508 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200509
510 if (len > count) {
511 ret = -EINVAL;
512 goto out;
513 }
514
515 if (copy_to_user(buf, user->buf, len)) {
516 ret = -EFAULT;
517 goto out;
518 }
519 ret = len;
520out:
521 mutex_unlock(&user->lock);
522 return ret;
523}
524
525static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
526{
527 struct devkmsg_user *user = file->private_data;
528 loff_t ret = 0;
529
530 if (!user)
531 return -EBADF;
532 if (offset)
533 return -ESPIPE;
534
liu chuansheng5c53d812012-07-06 09:50:08 -0700535 raw_spin_lock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200536 switch (whence) {
537 case SEEK_SET:
538 /* the first record */
539 user->idx = log_first_idx;
540 user->seq = log_first_seq;
541 break;
542 case SEEK_DATA:
543 /*
544 * The first record after the last SYSLOG_ACTION_CLEAR,
545 * like issued by 'dmesg -c'. Reading /dev/kmsg itself
546 * changes no global state, and does not clear anything.
547 */
548 user->idx = clear_idx;
549 user->seq = clear_seq;
550 break;
551 case SEEK_END:
552 /* after the last record */
553 user->idx = log_next_idx;
554 user->seq = log_next_seq;
555 break;
556 default:
557 ret = -EINVAL;
558 }
liu chuansheng5c53d812012-07-06 09:50:08 -0700559 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200560 return ret;
561}
562
563static unsigned int devkmsg_poll(struct file *file, poll_table *wait)
564{
565 struct devkmsg_user *user = file->private_data;
566 int ret = 0;
567
568 if (!user)
569 return POLLERR|POLLNVAL;
570
571 poll_wait(file, &log_wait, wait);
572
liu chuansheng5c53d812012-07-06 09:50:08 -0700573 raw_spin_lock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200574 if (user->seq < log_next_seq) {
575 /* return error when data has vanished underneath us */
576 if (user->seq < log_first_seq)
577 ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI;
578 ret = POLLIN|POLLRDNORM;
579 }
liu chuansheng5c53d812012-07-06 09:50:08 -0700580 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200581
582 return ret;
583}
584
585static int devkmsg_open(struct inode *inode, struct file *file)
586{
587 struct devkmsg_user *user;
588 int err;
589
590 /* write-only does not need any file context */
591 if ((file->f_flags & O_ACCMODE) == O_WRONLY)
592 return 0;
593
594 err = security_syslog(SYSLOG_ACTION_READ_ALL);
595 if (err)
596 return err;
597
598 user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL);
599 if (!user)
600 return -ENOMEM;
601
602 mutex_init(&user->lock);
603
liu chuansheng5c53d812012-07-06 09:50:08 -0700604 raw_spin_lock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200605 user->idx = log_first_idx;
606 user->seq = log_first_seq;
liu chuansheng5c53d812012-07-06 09:50:08 -0700607 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200608
609 file->private_data = user;
610 return 0;
611}
612
613static int devkmsg_release(struct inode *inode, struct file *file)
614{
615 struct devkmsg_user *user = file->private_data;
616
617 if (!user)
618 return 0;
619
620 mutex_destroy(&user->lock);
621 kfree(user);
622 return 0;
623}
624
625const struct file_operations kmsg_fops = {
626 .open = devkmsg_open,
627 .read = devkmsg_read,
628 .aio_write = devkmsg_writev,
629 .llseek = devkmsg_llseek,
630 .poll = devkmsg_poll,
631 .release = devkmsg_release,
632};
633
Neil Horman04d491a2009-04-02 16:58:57 -0700634#ifdef CONFIG_KEXEC
635/*
636 * This appends the listed symbols to /proc/vmcoreinfo
637 *
638 * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
639 * obtain access to symbols that are otherwise very difficult to locate. These
640 * symbols are specifically used so that utilities can access and extract the
641 * dmesg log from a vmcore file after a crash.
642 */
643void log_buf_kexec_setup(void)
644{
645 VMCOREINFO_SYMBOL(log_buf);
Neil Horman04d491a2009-04-02 16:58:57 -0700646 VMCOREINFO_SYMBOL(log_buf_len);
Kay Sievers7ff95542012-05-03 02:29:13 +0200647 VMCOREINFO_SYMBOL(log_first_idx);
648 VMCOREINFO_SYMBOL(log_next_idx);
Neil Horman04d491a2009-04-02 16:58:57 -0700649}
650#endif
651
Mike Travis162a7e72011-05-24 17:13:20 -0700652/* requested log_buf_len from kernel cmdline */
653static unsigned long __initdata new_log_buf_len;
654
655/* save requested log_buf_len since it's too early to process it */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656static int __init log_buf_len_setup(char *str)
657{
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800658 unsigned size = memparse(str, &str);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659
660 if (size)
661 size = roundup_pow_of_two(size);
Mike Travis162a7e72011-05-24 17:13:20 -0700662 if (size > log_buf_len)
663 new_log_buf_len = size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664
Mike Travis162a7e72011-05-24 17:13:20 -0700665 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666}
Mike Travis162a7e72011-05-24 17:13:20 -0700667early_param("log_buf_len", log_buf_len_setup);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668
Mike Travis162a7e72011-05-24 17:13:20 -0700669void __init setup_log_buf(int early)
670{
671 unsigned long flags;
Mike Travis162a7e72011-05-24 17:13:20 -0700672 char *new_log_buf;
673 int free;
674
675 if (!new_log_buf_len)
676 return;
677
678 if (early) {
679 unsigned long mem;
680
681 mem = memblock_alloc(new_log_buf_len, PAGE_SIZE);
Tejun Heo1f5026a2011-07-12 09:58:09 +0200682 if (!mem)
Mike Travis162a7e72011-05-24 17:13:20 -0700683 return;
684 new_log_buf = __va(mem);
685 } else {
686 new_log_buf = alloc_bootmem_nopanic(new_log_buf_len);
687 }
688
689 if (unlikely(!new_log_buf)) {
690 pr_err("log_buf_len: %ld bytes not available\n",
691 new_log_buf_len);
692 return;
693 }
694
Thomas Gleixner07354eb2009-07-25 17:50:36 +0200695 raw_spin_lock_irqsave(&logbuf_lock, flags);
Mike Travis162a7e72011-05-24 17:13:20 -0700696 log_buf_len = new_log_buf_len;
697 log_buf = new_log_buf;
698 new_log_buf_len = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +0200699 free = __LOG_BUF_LEN - log_next_idx;
700 memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
Thomas Gleixner07354eb2009-07-25 17:50:36 +0200701 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
Mike Travis162a7e72011-05-24 17:13:20 -0700702
703 pr_info("log_buf_len: %d\n", log_buf_len);
704 pr_info("early log buf free: %d(%d%%)\n",
705 free, (free * 100) / __LOG_BUF_LEN);
706}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700708#ifdef CONFIG_BOOT_PRINTK_DELAY
709
Namhyung Kim674dff62010-10-26 14:22:48 -0700710static int boot_delay; /* msecs delay after each printk during bootup */
Dave Young3a3b6ed2009-09-22 16:43:31 -0700711static unsigned long long loops_per_msec; /* based on boot_delay */
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700712
713static int __init boot_delay_setup(char *str)
714{
715 unsigned long lpj;
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700716
717 lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */
718 loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
719
720 get_option(&str, &boot_delay);
721 if (boot_delay > 10 * 1000)
722 boot_delay = 0;
723
Dave Young3a3b6ed2009-09-22 16:43:31 -0700724 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
725 "HZ: %d, loops_per_msec: %llu\n",
726 boot_delay, preset_lpj, lpj, HZ, loops_per_msec);
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700727 return 1;
728}
729__setup("boot_delay=", boot_delay_setup);
730
731static void boot_delay_msec(void)
732{
733 unsigned long long k;
734 unsigned long timeout;
735
736 if (boot_delay == 0 || system_state != SYSTEM_BOOTING)
737 return;
738
Dave Young3a3b6ed2009-09-22 16:43:31 -0700739 k = (unsigned long long)loops_per_msec * boot_delay;
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700740
741 timeout = jiffies + msecs_to_jiffies(boot_delay);
742 while (k) {
743 k--;
744 cpu_relax();
745 /*
746 * use (volatile) jiffies to prevent
747 * compiler reduction; loop termination via jiffies
748 * is secondary and may or may not happen.
749 */
750 if (time_after(jiffies, timeout))
751 break;
752 touch_nmi_watchdog();
753 }
754}
755#else
756static inline void boot_delay_msec(void)
757{
758}
759#endif
760
Dan Rosenbergeaf06b22010-11-11 14:05:18 -0800761#ifdef CONFIG_SECURITY_DMESG_RESTRICT
762int dmesg_restrict = 1;
763#else
764int dmesg_restrict;
765#endif
766
Linus Torvaldsee24aeb2011-02-10 17:53:55 -0800767static int syslog_action_restricted(int type)
768{
769 if (dmesg_restrict)
770 return 1;
771 /* Unless restricted, we allow "read all" and "get buffer size" for everybody */
772 return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER;
773}
774
775static int check_syslog_permissions(int type, bool from_file)
776{
777 /*
778 * If this is from /proc/kmsg and we've already opened it, then we've
779 * already done the capabilities checks at open time.
780 */
781 if (from_file && type != SYSLOG_ACTION_OPEN)
782 return 0;
783
784 if (syslog_action_restricted(type)) {
785 if (capable(CAP_SYSLOG))
786 return 0;
787 /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */
788 if (capable(CAP_SYS_ADMIN)) {
Jonathan Niederf2c0d022011-08-08 06:22:43 +0200789 printk_once(KERN_WARNING "%s (%d): "
790 "Attempt to access syslog with CAP_SYS_ADMIN "
791 "but no CAP_SYSLOG (deprecated).\n",
792 current->comm, task_pid_nr(current));
Linus Torvaldsee24aeb2011-02-10 17:53:55 -0800793 return 0;
794 }
795 return -EPERM;
796 }
797 return 0;
798}
799
Kay Sievers7ff95542012-05-03 02:29:13 +0200800#if defined(CONFIG_PRINTK_TIME)
801static bool printk_time = 1;
802#else
803static bool printk_time;
804#endif
805module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
806
Kay Sievers084681d2012-06-28 09:38:53 +0200807static size_t print_time(u64 ts, char *buf)
808{
809 unsigned long rem_nsec;
810
811 if (!printk_time)
812 return 0;
813
814 if (!buf)
815 return 15;
816
817 rem_nsec = do_div(ts, 1000000000);
818 return sprintf(buf, "[%5lu.%06lu] ",
819 (unsigned long)ts, rem_nsec / 1000);
820}
821
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200822static size_t print_prefix(const struct log *msg, bool syslog, char *buf)
Kay Sievers649e6ee2012-05-10 04:30:45 +0200823{
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200824 size_t len = 0;
Kay Sievers43a73a52012-07-06 09:50:09 -0700825 unsigned int prefix = (msg->facility << 3) | msg->level;
Kay Sievers649e6ee2012-05-10 04:30:45 +0200826
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200827 if (syslog) {
828 if (buf) {
Kay Sievers43a73a52012-07-06 09:50:09 -0700829 len += sprintf(buf, "<%u>", prefix);
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200830 } else {
831 len += 3;
Kay Sievers43a73a52012-07-06 09:50:09 -0700832 if (prefix > 999)
833 len += 3;
834 else if (prefix > 99)
835 len += 2;
836 else if (prefix > 9)
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200837 len++;
838 }
Kay Sievers7ff95542012-05-03 02:29:13 +0200839 }
840
Kay Sievers084681d2012-06-28 09:38:53 +0200841 len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200842 return len;
843}
844
Kay Sievers5becfb12012-07-09 12:15:42 -0700845static size_t msg_print_text(const struct log *msg, enum log_flags prev,
846 bool syslog, char *buf, size_t size)
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200847{
848 const char *text = log_text(msg);
849 size_t text_size = msg->text_len;
Kay Sievers5becfb12012-07-09 12:15:42 -0700850 bool prefix = true;
851 bool newline = true;
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200852 size_t len = 0;
853
Kay Sievers5becfb12012-07-09 12:15:42 -0700854 if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
855 prefix = false;
856
857 if (msg->flags & LOG_CONT) {
858 if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE))
859 prefix = false;
860
861 if (!(msg->flags & LOG_NEWLINE))
862 newline = false;
863 }
864
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200865 do {
866 const char *next = memchr(text, '\n', text_size);
867 size_t text_len;
868
869 if (next) {
870 text_len = next - text;
871 next++;
872 text_size -= next - text;
873 } else {
874 text_len = text_size;
875 }
876
877 if (buf) {
878 if (print_prefix(msg, syslog, NULL) +
879 text_len + 1>= size - len)
880 break;
881
Kay Sievers5becfb12012-07-09 12:15:42 -0700882 if (prefix)
883 len += print_prefix(msg, syslog, buf + len);
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200884 memcpy(buf + len, text, text_len);
885 len += text_len;
Kay Sievers5becfb12012-07-09 12:15:42 -0700886 if (next || newline)
887 buf[len++] = '\n';
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200888 } else {
889 /* SYSLOG_ACTION_* buffer size only calculation */
Kay Sievers5becfb12012-07-09 12:15:42 -0700890 if (prefix)
891 len += print_prefix(msg, syslog, NULL);
892 len += text_len;
893 if (next || newline)
894 len++;
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200895 }
896
Kay Sievers5becfb12012-07-09 12:15:42 -0700897 prefix = true;
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200898 text = next;
899 } while (text);
900
Kay Sievers7ff95542012-05-03 02:29:13 +0200901 return len;
902}
903
904static int syslog_print(char __user *buf, int size)
905{
906 char *text;
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200907 struct log *msg;
Jan Beulich116e90b2012-06-22 16:36:09 +0100908 int len = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +0200909
910 text = kmalloc(LOG_LINE_MAX, GFP_KERNEL);
911 if (!text)
912 return -ENOMEM;
913
Jan Beulich116e90b2012-06-22 16:36:09 +0100914 while (size > 0) {
915 size_t n;
Kay Sieverseb02dac2012-07-09 10:05:10 -0700916 size_t skip;
Kay Sievers7ff95542012-05-03 02:29:13 +0200917
Jan Beulich116e90b2012-06-22 16:36:09 +0100918 raw_spin_lock_irq(&logbuf_lock);
919 if (syslog_seq < log_first_seq) {
920 /* messages are gone, move to first one */
921 syslog_seq = log_first_seq;
922 syslog_idx = log_first_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -0700923 syslog_prev = 0;
Kay Sieverseb02dac2012-07-09 10:05:10 -0700924 syslog_partial = 0;
Jan Beulich116e90b2012-06-22 16:36:09 +0100925 }
926 if (syslog_seq == log_next_seq) {
927 raw_spin_unlock_irq(&logbuf_lock);
928 break;
929 }
Kay Sieverseb02dac2012-07-09 10:05:10 -0700930
931 skip = syslog_partial;
Jan Beulich116e90b2012-06-22 16:36:09 +0100932 msg = log_from_idx(syslog_idx);
Kay Sievers5becfb12012-07-09 12:15:42 -0700933 n = msg_print_text(msg, syslog_prev, true, text, LOG_LINE_MAX);
Kay Sieverseb02dac2012-07-09 10:05:10 -0700934 if (n - syslog_partial <= size) {
935 /* message fits into buffer, move forward */
Jan Beulich116e90b2012-06-22 16:36:09 +0100936 syslog_idx = log_next(syslog_idx);
937 syslog_seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -0700938 syslog_prev = msg->flags;
Kay Sieverseb02dac2012-07-09 10:05:10 -0700939 n -= syslog_partial;
940 syslog_partial = 0;
941 } else if (!len){
942 /* partial read(), remember position */
943 n = size;
944 syslog_partial += n;
Jan Beulich116e90b2012-06-22 16:36:09 +0100945 } else
946 n = 0;
947 raw_spin_unlock_irq(&logbuf_lock);
948
949 if (!n)
950 break;
951
Kay Sieverseb02dac2012-07-09 10:05:10 -0700952 if (copy_to_user(buf, text + skip, n)) {
Jan Beulich116e90b2012-06-22 16:36:09 +0100953 if (!len)
954 len = -EFAULT;
955 break;
956 }
Kay Sieverseb02dac2012-07-09 10:05:10 -0700957
958 len += n;
959 size -= n;
960 buf += n;
Jan Beulich116e90b2012-06-22 16:36:09 +0100961 }
Kay Sievers7ff95542012-05-03 02:29:13 +0200962
963 kfree(text);
964 return len;
965}
966
967static int syslog_print_all(char __user *buf, int size, bool clear)
968{
969 char *text;
970 int len = 0;
971
972 text = kmalloc(LOG_LINE_MAX, GFP_KERNEL);
973 if (!text)
974 return -ENOMEM;
975
976 raw_spin_lock_irq(&logbuf_lock);
977 if (buf) {
978 u64 next_seq;
979 u64 seq;
980 u32 idx;
Kay Sievers5becfb12012-07-09 12:15:42 -0700981 enum log_flags prev;
Kay Sievers7ff95542012-05-03 02:29:13 +0200982
983 if (clear_seq < log_first_seq) {
984 /* messages are gone, move to first available one */
985 clear_seq = log_first_seq;
986 clear_idx = log_first_idx;
987 }
988
989 /*
990 * Find first record that fits, including all following records,
991 * into the user-provided buffer for this dump.
Kay Sieverse2ae7152012-06-15 14:07:51 +0200992 */
Kay Sievers7ff95542012-05-03 02:29:13 +0200993 seq = clear_seq;
994 idx = clear_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -0700995 prev = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +0200996 while (seq < log_next_seq) {
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200997 struct log *msg = log_from_idx(idx);
998
Kay Sievers5becfb12012-07-09 12:15:42 -0700999 len += msg_print_text(msg, prev, true, NULL, 0);
Kay Sievers7ff95542012-05-03 02:29:13 +02001000 idx = log_next(idx);
1001 seq++;
1002 }
Kay Sieverse2ae7152012-06-15 14:07:51 +02001003
1004 /* move first record forward until length fits into the buffer */
Kay Sievers7ff95542012-05-03 02:29:13 +02001005 seq = clear_seq;
1006 idx = clear_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07001007 prev = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001008 while (len > size && seq < log_next_seq) {
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001009 struct log *msg = log_from_idx(idx);
1010
Kay Sievers5becfb12012-07-09 12:15:42 -07001011 len -= msg_print_text(msg, prev, true, NULL, 0);
Kay Sievers7ff95542012-05-03 02:29:13 +02001012 idx = log_next(idx);
1013 seq++;
1014 }
1015
Kay Sieverse2ae7152012-06-15 14:07:51 +02001016 /* last message fitting into this dump */
Kay Sievers7ff95542012-05-03 02:29:13 +02001017 next_seq = log_next_seq;
1018
1019 len = 0;
Kay Sievers5becfb12012-07-09 12:15:42 -07001020 prev = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001021 while (len >= 0 && seq < next_seq) {
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001022 struct log *msg = log_from_idx(idx);
Kay Sievers7ff95542012-05-03 02:29:13 +02001023 int textlen;
1024
Kay Sievers5becfb12012-07-09 12:15:42 -07001025 textlen = msg_print_text(msg, prev, true, text, LOG_LINE_MAX);
Kay Sievers7ff95542012-05-03 02:29:13 +02001026 if (textlen < 0) {
1027 len = textlen;
1028 break;
1029 }
1030 idx = log_next(idx);
1031 seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07001032 prev = msg->flags;
Kay Sievers7ff95542012-05-03 02:29:13 +02001033
1034 raw_spin_unlock_irq(&logbuf_lock);
1035 if (copy_to_user(buf + len, text, textlen))
1036 len = -EFAULT;
1037 else
1038 len += textlen;
1039 raw_spin_lock_irq(&logbuf_lock);
1040
1041 if (seq < log_first_seq) {
1042 /* messages are gone, move to next one */
1043 seq = log_first_seq;
1044 idx = log_first_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07001045 prev = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001046 }
1047 }
1048 }
1049
1050 if (clear) {
1051 clear_seq = log_next_seq;
1052 clear_idx = log_next_idx;
1053 }
1054 raw_spin_unlock_irq(&logbuf_lock);
1055
1056 kfree(text);
1057 return len;
1058}
1059
Kees Cook00234592010-02-03 15:36:43 -08001060int do_syslog(int type, char __user *buf, int len, bool from_file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061{
Kay Sievers7ff95542012-05-03 02:29:13 +02001062 bool clear = false;
1063 static int saved_console_loglevel = -1;
Linus Torvaldsee24aeb2011-02-10 17:53:55 -08001064 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065
Linus Torvaldsee24aeb2011-02-10 17:53:55 -08001066 error = check_syslog_permissions(type, from_file);
1067 if (error)
1068 goto out;
Eric Paris12b30522010-11-15 18:36:29 -05001069
1070 error = security_syslog(type);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071 if (error)
1072 return error;
1073
1074 switch (type) {
Kees Cookd78ca3c2010-02-03 15:37:13 -08001075 case SYSLOG_ACTION_CLOSE: /* Close log */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001076 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001077 case SYSLOG_ACTION_OPEN: /* Open log */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001079 case SYSLOG_ACTION_READ: /* Read from log */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080 error = -EINVAL;
1081 if (!buf || len < 0)
1082 goto out;
1083 error = 0;
1084 if (!len)
1085 goto out;
1086 if (!access_ok(VERIFY_WRITE, buf, len)) {
1087 error = -EFAULT;
1088 goto out;
1089 }
Yuanhan Liu4a77a5a2012-06-16 21:21:51 +08001090 error = wait_event_interruptible(log_wait,
1091 syslog_seq != log_next_seq);
Kay Sieverscb424ff2012-07-06 09:50:09 -07001092 if (error)
Yuanhan Liu4a77a5a2012-06-16 21:21:51 +08001093 goto out;
Kay Sievers7ff95542012-05-03 02:29:13 +02001094 error = syslog_print(buf, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001096 /* Read/clear last kernel messages */
1097 case SYSLOG_ACTION_READ_CLEAR:
Kay Sievers7ff95542012-05-03 02:29:13 +02001098 clear = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 /* FALL THRU */
Kees Cookd78ca3c2010-02-03 15:37:13 -08001100 /* Read last kernel messages */
1101 case SYSLOG_ACTION_READ_ALL:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 error = -EINVAL;
1103 if (!buf || len < 0)
1104 goto out;
1105 error = 0;
1106 if (!len)
1107 goto out;
1108 if (!access_ok(VERIFY_WRITE, buf, len)) {
1109 error = -EFAULT;
1110 goto out;
1111 }
Kay Sievers7ff95542012-05-03 02:29:13 +02001112 error = syslog_print_all(buf, len, clear);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001114 /* Clear ring buffer */
1115 case SYSLOG_ACTION_CLEAR:
Kay Sievers7ff95542012-05-03 02:29:13 +02001116 syslog_print_all(NULL, 0, true);
Alan Stern4661e352012-06-22 17:12:19 -04001117 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001118 /* Disable logging to console */
1119 case SYSLOG_ACTION_CONSOLE_OFF:
Frans Pop1aaad492009-07-06 13:31:48 +02001120 if (saved_console_loglevel == -1)
1121 saved_console_loglevel = console_loglevel;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 console_loglevel = minimum_console_loglevel;
1123 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001124 /* Enable logging to console */
1125 case SYSLOG_ACTION_CONSOLE_ON:
Frans Pop1aaad492009-07-06 13:31:48 +02001126 if (saved_console_loglevel != -1) {
1127 console_loglevel = saved_console_loglevel;
1128 saved_console_loglevel = -1;
1129 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001131 /* Set level of messages printed to console */
1132 case SYSLOG_ACTION_CONSOLE_LEVEL:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133 error = -EINVAL;
1134 if (len < 1 || len > 8)
1135 goto out;
1136 if (len < minimum_console_loglevel)
1137 len = minimum_console_loglevel;
1138 console_loglevel = len;
Frans Pop1aaad492009-07-06 13:31:48 +02001139 /* Implicitly re-enable logging to console */
1140 saved_console_loglevel = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 error = 0;
1142 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001143 /* Number of chars in the log buffer */
1144 case SYSLOG_ACTION_SIZE_UNREAD:
Kay Sievers7ff95542012-05-03 02:29:13 +02001145 raw_spin_lock_irq(&logbuf_lock);
1146 if (syslog_seq < log_first_seq) {
1147 /* messages are gone, move to first one */
1148 syslog_seq = log_first_seq;
1149 syslog_idx = log_first_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07001150 syslog_prev = 0;
Kay Sieverseb02dac2012-07-09 10:05:10 -07001151 syslog_partial = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001152 }
1153 if (from_file) {
1154 /*
1155 * Short-cut for poll(/"proc/kmsg") which simply checks
1156 * for pending data, not the size; return the count of
1157 * records, not the length.
1158 */
1159 error = log_next_idx - syslog_idx;
1160 } else {
Kay Sievers5becfb12012-07-09 12:15:42 -07001161 u64 seq = syslog_seq;
1162 u32 idx = syslog_idx;
1163 enum log_flags prev = syslog_prev;
Kay Sievers7ff95542012-05-03 02:29:13 +02001164
1165 error = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001166 while (seq < log_next_seq) {
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001167 struct log *msg = log_from_idx(idx);
1168
Kay Sievers5becfb12012-07-09 12:15:42 -07001169 error += msg_print_text(msg, prev, true, NULL, 0);
Kay Sievers7ff95542012-05-03 02:29:13 +02001170 idx = log_next(idx);
1171 seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07001172 prev = msg->flags;
Kay Sievers7ff95542012-05-03 02:29:13 +02001173 }
Kay Sieverseb02dac2012-07-09 10:05:10 -07001174 error -= syslog_partial;
Kay Sievers7ff95542012-05-03 02:29:13 +02001175 }
1176 raw_spin_unlock_irq(&logbuf_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001178 /* Size of the log buffer */
1179 case SYSLOG_ACTION_SIZE_BUFFER:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 error = log_buf_len;
1181 break;
1182 default:
1183 error = -EINVAL;
1184 break;
1185 }
1186out:
1187 return error;
1188}
1189
Heiko Carstens1e7bfb22009-01-14 14:14:29 +01001190SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191{
Kees Cook00234592010-02-03 15:36:43 -08001192 return do_syslog(type, buf, len, SYSLOG_FROM_CALL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193}
1194
Rusty Russell2329abf2012-01-13 09:32:18 +10301195static bool __read_mostly ignore_loglevel;
Ingo Molnar792908222006-12-06 20:40:51 -08001196
Adrian Bunk99eea6a2006-12-22 01:07:00 -08001197static int __init ignore_loglevel_setup(char *str)
Ingo Molnar792908222006-12-06 20:40:51 -08001198{
1199 ignore_loglevel = 1;
1200 printk(KERN_INFO "debug: ignoring loglevel setting.\n");
1201
Ingo Molnarc4772d92008-01-31 22:45:23 +01001202 return 0;
Ingo Molnar792908222006-12-06 20:40:51 -08001203}
1204
Ingo Molnarc4772d92008-01-31 22:45:23 +01001205early_param("ignore_loglevel", ignore_loglevel_setup);
Rusty Russell29d4d6d2012-01-13 09:32:17 +10301206module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR);
Yanmin Zhang0eca6b72011-10-31 17:11:25 -07001207MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to"
1208 "print all kernel messages to the console.");
Ingo Molnar792908222006-12-06 20:40:51 -08001209
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211 * Call the console drivers, asking them to write out
1212 * log_buf[start] to log_buf[end - 1].
Torben Hohnac751ef2011-01-25 15:07:35 -08001213 * The console_lock must be held.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 */
Kay Sievers7ff95542012-05-03 02:29:13 +02001215static void call_console_drivers(int level, const char *text, size_t len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216{
Kay Sievers7ff95542012-05-03 02:29:13 +02001217 struct console *con;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218
Kay Sievers7ff95542012-05-03 02:29:13 +02001219 trace_console(text, 0, len, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220
Kay Sievers7ff95542012-05-03 02:29:13 +02001221 if (level >= console_loglevel && !ignore_loglevel)
1222 return;
1223 if (!console_drivers)
1224 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001225
Kay Sievers7ff95542012-05-03 02:29:13 +02001226 for_each_console(con) {
1227 if (exclusive_console && con != exclusive_console)
1228 continue;
1229 if (!(con->flags & CON_ENABLED))
1230 continue;
1231 if (!con->write)
1232 continue;
1233 if (!cpu_online(smp_processor_id()) &&
1234 !(con->flags & CON_ANYTIME))
1235 continue;
1236 con->write(con, text, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238}
1239
1240/*
1241 * Zap console related locks when oopsing. Only zap at most once
1242 * every 10 seconds, to leave time for slow consoles to print a
1243 * full oops.
1244 */
1245static void zap_locks(void)
1246{
1247 static unsigned long oops_timestamp;
1248
1249 if (time_after_eq(jiffies, oops_timestamp) &&
Jesper Juhl40dc5652005-10-30 15:02:46 -08001250 !time_after(jiffies, oops_timestamp + 30 * HZ))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251 return;
1252
1253 oops_timestamp = jiffies;
1254
Peter Zijlstra94d24fc2011-06-07 11:17:30 +02001255 debug_locks_off();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001256 /* If a crash is occurring, make sure we can't deadlock */
Thomas Gleixner07354eb2009-07-25 17:50:36 +02001257 raw_spin_lock_init(&logbuf_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001258 /* And make sure that we print immediately */
Thomas Gleixner5b8c4f22010-09-07 14:33:43 +00001259 sema_init(&console_sem, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001260}
1261
Michael Ellerman76a8ad22006-06-25 05:47:40 -07001262/* Check if we have any console registered that can be called early in boot. */
1263static int have_callable_console(void)
1264{
1265 struct console *con;
1266
Robin Getz4d091612009-07-01 21:08:37 -04001267 for_each_console(con)
Michael Ellerman76a8ad22006-06-25 05:47:40 -07001268 if (con->flags & CON_ANYTIME)
1269 return 1;
1270
1271 return 0;
1272}
1273
Linus Torvalds266c2e02008-03-24 19:25:08 -07001274/*
1275 * Can we actually use the console at this time on this cpu?
1276 *
1277 * Console drivers may assume that per-cpu resources have
1278 * been allocated. So unless they're explicitly marked as
1279 * being able to cope (CON_ANYTIME) don't call them until
1280 * this CPU is officially up.
1281 */
1282static inline int can_use_console(unsigned int cpu)
1283{
1284 return cpu_online(cpu) || have_callable_console();
1285}
1286
1287/*
1288 * Try to get console ownership to actually show the kernel
1289 * messages from a 'printk'. Return true (and with the
Torben Hohnac751ef2011-01-25 15:07:35 -08001290 * console_lock held, and 'console_locked' set) if it
Linus Torvalds266c2e02008-03-24 19:25:08 -07001291 * is successful, false otherwise.
1292 *
1293 * This gets called with the 'logbuf_lock' spinlock held and
1294 * interrupts disabled. It should return with 'lockbuf_lock'
1295 * released but interrupts still disabled.
1296 */
Torben Hohnac751ef2011-01-25 15:07:35 -08001297static int console_trylock_for_printk(unsigned int cpu)
Namhyung Kim8155c022010-10-26 14:22:47 -07001298 __releases(&logbuf_lock)
Linus Torvalds266c2e02008-03-24 19:25:08 -07001299{
Peter Zijlstra0b5e1c52011-06-07 11:15:33 +02001300 int retval = 0, wake = 0;
Linus Torvalds266c2e02008-03-24 19:25:08 -07001301
Torben Hohnac751ef2011-01-25 15:07:35 -08001302 if (console_trylock()) {
Linus Torvalds093a07e2008-04-15 13:09:54 -07001303 retval = 1;
1304
1305 /*
1306 * If we can't use the console, we need to release
1307 * the console semaphore by hand to avoid flushing
1308 * the buffer. We need to hold the console semaphore
1309 * in order to do this test safely.
1310 */
1311 if (!can_use_console(cpu)) {
1312 console_locked = 0;
Peter Zijlstra0b5e1c52011-06-07 11:15:33 +02001313 wake = 1;
Linus Torvalds093a07e2008-04-15 13:09:54 -07001314 retval = 0;
1315 }
1316 }
Kay Sievers7ff95542012-05-03 02:29:13 +02001317 logbuf_cpu = UINT_MAX;
Peter Zijlstra0b5e1c52011-06-07 11:15:33 +02001318 if (wake)
1319 up(&console_sem);
Thomas Gleixner07354eb2009-07-25 17:50:36 +02001320 raw_spin_unlock(&logbuf_lock);
Linus Torvalds266c2e02008-03-24 19:25:08 -07001321 return retval;
1322}
Ingo Molnar32a76002008-01-25 21:07:58 +01001323
Dave Youngaf913222009-09-22 16:43:33 -07001324int printk_delay_msec __read_mostly;
1325
1326static inline void printk_delay(void)
1327{
1328 if (unlikely(printk_delay_msec)) {
1329 int m = printk_delay_msec;
1330
1331 while (m--) {
1332 mdelay(1);
1333 touch_nmi_watchdog();
1334 }
1335 }
1336}
1337
Kay Sievers084681d2012-06-28 09:38:53 +02001338/*
1339 * Continuation lines are buffered, and not committed to the record buffer
1340 * until the line is complete, or a race forces it. The line fragments
1341 * though, are printed immediately to the consoles to ensure everything has
1342 * reached the console in case of a kernel crash.
1343 */
1344static struct cont {
1345 char buf[LOG_LINE_MAX];
1346 size_t len; /* length == 0 means unused buffer */
1347 size_t cons; /* bytes written to console */
1348 struct task_struct *owner; /* task of first print*/
1349 u64 ts_nsec; /* time of first print */
1350 u8 level; /* log level of first message */
1351 u8 facility; /* log level of first message */
1352 bool flushed:1; /* buffer sealed and committed */
1353} cont;
1354
1355static void cont_flush(void)
1356{
1357 if (cont.flushed)
1358 return;
1359 if (cont.len == 0)
1360 return;
1361
1362 log_store(cont.facility, cont.level, LOG_NOCONS, cont.ts_nsec,
1363 NULL, 0, cont.buf, cont.len);
1364
1365 cont.flushed = true;
1366}
1367
1368static bool cont_add(int facility, int level, const char *text, size_t len)
1369{
1370 if (cont.len && cont.flushed)
1371 return false;
1372
1373 if (cont.len + len > sizeof(cont.buf)) {
1374 cont_flush();
1375 return false;
1376 }
1377
1378 if (!cont.len) {
1379 cont.facility = facility;
1380 cont.level = level;
1381 cont.owner = current;
1382 cont.ts_nsec = local_clock();
1383 cont.cons = 0;
1384 cont.flushed = false;
1385 }
1386
1387 memcpy(cont.buf + cont.len, text, len);
1388 cont.len += len;
1389 return true;
1390}
1391
1392static size_t cont_print_text(char *text, size_t size)
1393{
1394 size_t textlen = 0;
1395 size_t len;
1396
1397 if (cont.cons == 0) {
1398 textlen += print_time(cont.ts_nsec, text);
1399 size -= textlen;
1400 }
1401
1402 len = cont.len - cont.cons;
1403 if (len > 0) {
1404 if (len+1 > size)
1405 len = size-1;
1406 memcpy(text + textlen, cont.buf + cont.cons, len);
1407 textlen += len;
1408 cont.cons = cont.len;
1409 }
1410
1411 if (cont.flushed) {
1412 text[textlen++] = '\n';
1413 /* got everything, release buffer */
1414 cont.len = 0;
1415 }
1416 return textlen;
1417}
1418
Kay Sievers7ff95542012-05-03 02:29:13 +02001419asmlinkage int vprintk_emit(int facility, int level,
1420 const char *dict, size_t dictlen,
1421 const char *fmt, va_list args)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001422{
Kay Sievers7ff95542012-05-03 02:29:13 +02001423 static int recursion_bug;
Kay Sievers7ff95542012-05-03 02:29:13 +02001424 static char textbuf[LOG_LINE_MAX];
1425 char *text = textbuf;
Kay Sieversc313af12012-05-14 20:46:27 +02001426 size_t text_len;
Kay Sievers5becfb12012-07-09 12:15:42 -07001427 enum log_flags lflags = 0;
Nick Andrewac60ad72008-05-12 21:21:04 +02001428 unsigned long flags;
Ingo Molnar32a76002008-01-25 21:07:58 +01001429 int this_cpu;
Kay Sievers7ff95542012-05-03 02:29:13 +02001430 int printed_len = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431
Randy Dunlapbfe8df32007-10-16 01:23:46 -07001432 boot_delay_msec();
Dave Youngaf913222009-09-22 16:43:33 -07001433 printk_delay();
Randy Dunlapbfe8df32007-10-16 01:23:46 -07001434
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435 /* This stops the holder of console_sem just where we want him */
Peter Zijlstra1a9a8ae2011-06-07 11:17:30 +02001436 local_irq_save(flags);
Ingo Molnar32a76002008-01-25 21:07:58 +01001437 this_cpu = smp_processor_id();
1438
1439 /*
1440 * Ouch, printk recursed into itself!
1441 */
Kay Sievers7ff95542012-05-03 02:29:13 +02001442 if (unlikely(logbuf_cpu == this_cpu)) {
Ingo Molnar32a76002008-01-25 21:07:58 +01001443 /*
1444 * If a crash is occurring during printk() on this CPU,
1445 * then try to get the crash message out but make sure
1446 * we can't deadlock. Otherwise just return to avoid the
1447 * recursion and return - but flag the recursion so that
1448 * it can be printed at the next appropriate moment:
1449 */
Peter Zijlstra94d24fc2011-06-07 11:17:30 +02001450 if (!oops_in_progress && !lockdep_recursing(current)) {
Tejun Heo3b8945e2008-05-12 21:21:04 +02001451 recursion_bug = 1;
Ingo Molnar32a76002008-01-25 21:07:58 +01001452 goto out_restore_irqs;
1453 }
1454 zap_locks();
1455 }
1456
Ingo Molnara0f1ccf2006-07-03 00:24:58 -07001457 lockdep_off();
Thomas Gleixner07354eb2009-07-25 17:50:36 +02001458 raw_spin_lock(&logbuf_lock);
Kay Sievers7ff95542012-05-03 02:29:13 +02001459 logbuf_cpu = this_cpu;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460
Tejun Heo3b8945e2008-05-12 21:21:04 +02001461 if (recursion_bug) {
Kay Sievers7ff95542012-05-03 02:29:13 +02001462 static const char recursion_msg[] =
1463 "BUG: recent printk recursion!";
1464
Tejun Heo3b8945e2008-05-12 21:21:04 +02001465 recursion_bug = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001466 printed_len += strlen(recursion_msg);
1467 /* emit KERN_CRIT message */
Kay Sievers5becfb12012-07-09 12:15:42 -07001468 log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
Kay Sievers084681d2012-06-28 09:38:53 +02001469 NULL, 0, recursion_msg, printed_len);
Linus Torvalds5fd29d62009-06-16 10:57:02 -07001470 }
1471
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472 /*
Kay Sievers7ff95542012-05-03 02:29:13 +02001473 * The printf needs to come first; we need the syslog
1474 * prefix which might be passed-in as a parameter.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001475 */
Kay Sieversc313af12012-05-14 20:46:27 +02001476 text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
Nick Andrewac60ad72008-05-12 21:21:04 +02001477
Kay Sievers7ff95542012-05-03 02:29:13 +02001478 /* mark and strip a trailing newline */
Kay Sieversc313af12012-05-14 20:46:27 +02001479 if (text_len && text[text_len-1] == '\n') {
1480 text_len--;
Kay Sievers5becfb12012-07-09 12:15:42 -07001481 lflags |= LOG_NEWLINE;
Kay Sievers7ff95542012-05-03 02:29:13 +02001482 }
Kay Sievers9d90c8d2011-03-13 03:19:51 +01001483
Kay Sieversc313af12012-05-14 20:46:27 +02001484 /* strip syslog prefix and extract log level or control flags */
Kay Sievers7ff95542012-05-03 02:29:13 +02001485 if (text[0] == '<' && text[1] && text[2] == '>') {
1486 switch (text[1]) {
1487 case '0' ... '7':
1488 if (level == -1)
1489 level = text[1] - '0';
Kay Sievers7ff95542012-05-03 02:29:13 +02001490 case 'd': /* KERN_DEFAULT */
Kay Sievers5becfb12012-07-09 12:15:42 -07001491 lflags |= LOG_PREFIX;
Kay Sievers5c5d5ca2012-05-10 04:32:53 +02001492 case 'c': /* KERN_CONT */
Kay Sievers7ff95542012-05-03 02:29:13 +02001493 text += 3;
Kay Sieversc313af12012-05-14 20:46:27 +02001494 text_len -= 3;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495 }
Kay Sievers7ff95542012-05-03 02:29:13 +02001496 }
Nick Andrewac60ad72008-05-12 21:21:04 +02001497
Kay Sieversc313af12012-05-14 20:46:27 +02001498 if (level == -1)
1499 level = default_message_loglevel;
1500
Kay Sievers5becfb12012-07-09 12:15:42 -07001501 if (dict)
1502 lflags |= LOG_PREFIX|LOG_NEWLINE;
Kay Sievers7ff95542012-05-03 02:29:13 +02001503
Kay Sievers5becfb12012-07-09 12:15:42 -07001504 if (!(lflags & LOG_NEWLINE)) {
Kay Sievers084681d2012-06-28 09:38:53 +02001505 /*
1506 * Flush the conflicting buffer. An earlier newline was missing,
1507 * or another task also prints continuation lines.
1508 */
Kay Sievers5becfb12012-07-09 12:15:42 -07001509 if (cont.len && (lflags & LOG_PREFIX || cont.owner != current))
Kay Sievers084681d2012-06-28 09:38:53 +02001510 cont_flush();
Kay Sieversc313af12012-05-14 20:46:27 +02001511
Kay Sievers084681d2012-06-28 09:38:53 +02001512 /* buffer line if possible, otherwise store it right away */
1513 if (!cont_add(facility, level, text, text_len))
Kay Sievers5becfb12012-07-09 12:15:42 -07001514 log_store(facility, level, lflags | LOG_CONT, 0,
Kay Sieversc313af12012-05-14 20:46:27 +02001515 dict, dictlen, text, text_len);
Kay Sievers084681d2012-06-28 09:38:53 +02001516 } else {
1517 bool stored = false;
1518
1519 /*
Steven Rostedtd3620822012-06-29 11:40:11 -04001520 * If an earlier newline was missing and it was the same task,
1521 * either merge it with the current buffer and flush, or if
1522 * there was a race with interrupts (prefix == true) then just
1523 * flush it out and store this line separately.
Kay Sievers084681d2012-06-28 09:38:53 +02001524 */
Kay Sievers084681d2012-06-28 09:38:53 +02001525 if (cont.len && cont.owner == current) {
Kay Sievers5becfb12012-07-09 12:15:42 -07001526 if (!(lflags & LOG_PREFIX))
Steven Rostedtd3620822012-06-29 11:40:11 -04001527 stored = cont_add(facility, level, text, text_len);
Kay Sievers084681d2012-06-28 09:38:53 +02001528 cont_flush();
Kay Sieversc313af12012-05-14 20:46:27 +02001529 }
Kay Sievers084681d2012-06-28 09:38:53 +02001530
1531 if (!stored)
Kay Sievers5becfb12012-07-09 12:15:42 -07001532 log_store(facility, level, lflags, 0,
Kay Sievers084681d2012-06-28 09:38:53 +02001533 dict, dictlen, text, text_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534 }
Kay Sievers084681d2012-06-28 09:38:53 +02001535 printed_len += text_len;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536
Linus Torvalds266c2e02008-03-24 19:25:08 -07001537 /*
Kay Sievers7ff95542012-05-03 02:29:13 +02001538 * Try to acquire and then immediately release the console semaphore.
1539 * The release will print out buffers and wake up /dev/kmsg and syslog()
1540 * users.
Linus Torvalds266c2e02008-03-24 19:25:08 -07001541 *
Kay Sievers7ff95542012-05-03 02:29:13 +02001542 * The console_trylock_for_printk() function will release 'logbuf_lock'
1543 * regardless of whether it actually gets the console semaphore or not.
Linus Torvalds266c2e02008-03-24 19:25:08 -07001544 */
Torben Hohnac751ef2011-01-25 15:07:35 -08001545 if (console_trylock_for_printk(this_cpu))
1546 console_unlock();
Michael Ellerman76a8ad22006-06-25 05:47:40 -07001547
Linus Torvalds266c2e02008-03-24 19:25:08 -07001548 lockdep_on();
Ingo Molnar32a76002008-01-25 21:07:58 +01001549out_restore_irqs:
Peter Zijlstra1a9a8ae2011-06-07 11:17:30 +02001550 local_irq_restore(flags);
Michael Ellerman76a8ad22006-06-25 05:47:40 -07001551
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552 return printed_len;
1553}
Kay Sievers7ff95542012-05-03 02:29:13 +02001554EXPORT_SYMBOL(vprintk_emit);
1555
1556asmlinkage int vprintk(const char *fmt, va_list args)
1557{
1558 return vprintk_emit(0, -1, NULL, 0, fmt, args);
1559}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560EXPORT_SYMBOL(vprintk);
1561
Kay Sievers7ff95542012-05-03 02:29:13 +02001562asmlinkage int printk_emit(int facility, int level,
1563 const char *dict, size_t dictlen,
1564 const char *fmt, ...)
1565{
1566 va_list args;
1567 int r;
1568
1569 va_start(args, fmt);
1570 r = vprintk_emit(facility, level, dict, dictlen, fmt, args);
1571 va_end(args);
1572
1573 return r;
1574}
1575EXPORT_SYMBOL(printk_emit);
1576
1577/**
1578 * printk - print a kernel message
1579 * @fmt: format string
1580 *
1581 * This is printk(). It can be called from any context. We want it to work.
1582 *
1583 * We try to grab the console_lock. If we succeed, it's easy - we log the
1584 * output and call the console drivers. If we fail to get the semaphore, we
1585 * place the output into the log buffer and return. The current holder of
1586 * the console_sem will notice the new output in console_unlock(); and will
1587 * send it to the consoles before releasing the lock.
1588 *
1589 * One effect of this deferred printing is that code which calls printk() and
1590 * then changes console_loglevel may break. This is because console_loglevel
1591 * is inspected when the actual printing occurs.
1592 *
1593 * See also:
1594 * printf(3)
1595 *
1596 * See the vsnprintf() documentation for format string extensions over C99.
1597 */
1598asmlinkage int printk(const char *fmt, ...)
1599{
1600 va_list args;
1601 int r;
1602
1603#ifdef CONFIG_KGDB_KDB
1604 if (unlikely(kdb_trap_printk)) {
1605 va_start(args, fmt);
1606 r = vkdb_printf(fmt, args);
1607 va_end(args);
1608 return r;
1609 }
1610#endif
1611 va_start(args, fmt);
1612 r = vprintk_emit(0, -1, NULL, 0, fmt, args);
1613 va_end(args);
1614
1615 return r;
1616}
1617EXPORT_SYMBOL(printk);
Kay Sievers7f3a7812012-05-09 01:37:51 +02001618
Matt Mackalld59745c2005-05-01 08:59:02 -07001619#else
1620
Kay Sievers7f3a7812012-05-09 01:37:51 +02001621#define LOG_LINE_MAX 0
Kay Sievers084681d2012-06-28 09:38:53 +02001622static struct cont {
1623 size_t len;
1624 size_t cons;
1625 u8 level;
1626 bool flushed:1;
1627} cont;
Kay Sievers7f3a7812012-05-09 01:37:51 +02001628static struct log *log_from_idx(u32 idx) { return NULL; }
1629static u32 log_next(u32 idx) { return 0; }
Kay Sievers7f3a7812012-05-09 01:37:51 +02001630static void call_console_drivers(int level, const char *text, size_t len) {}
Kay Sievers5becfb12012-07-09 12:15:42 -07001631static size_t msg_print_text(const struct log *msg, enum log_flags prev,
1632 bool syslog, char *buf, size_t size) { return 0; }
Kay Sievers084681d2012-06-28 09:38:53 +02001633static size_t cont_print_text(char *text, size_t size) { return 0; }
Matt Mackalld59745c2005-05-01 08:59:02 -07001634
Kay Sievers7f3a7812012-05-09 01:37:51 +02001635#endif /* CONFIG_PRINTK */
Matt Mackalld59745c2005-05-01 08:59:02 -07001636
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001637static int __add_preferred_console(char *name, int idx, char *options,
1638 char *brl_options)
1639{
1640 struct console_cmdline *c;
1641 int i;
1642
1643 /*
1644 * See if this tty is not yet registered, and
1645 * if we have a slot free.
1646 */
1647 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
1648 if (strcmp(console_cmdline[i].name, name) == 0 &&
1649 console_cmdline[i].index == idx) {
1650 if (!brl_options)
1651 selected_console = i;
1652 return 0;
1653 }
1654 if (i == MAX_CMDLINECONSOLES)
1655 return -E2BIG;
1656 if (!brl_options)
1657 selected_console = i;
1658 c = &console_cmdline[i];
1659 strlcpy(c->name, name, sizeof(c->name));
1660 c->options = options;
1661#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1662 c->brl_options = brl_options;
1663#endif
1664 c->index = idx;
1665 return 0;
1666}
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001667/*
1668 * Set up a list of consoles. Called from init/main.c
1669 */
1670static int __init console_setup(char *str)
1671{
Yinghai Lueaa944a2007-07-15 23:37:27 -07001672 char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001673 char *s, *options, *brl_options = NULL;
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001674 int idx;
1675
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001676#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1677 if (!memcmp(str, "brl,", 4)) {
1678 brl_options = "";
1679 str += 4;
1680 } else if (!memcmp(str, "brl=", 4)) {
1681 brl_options = str + 4;
1682 str = strchr(brl_options, ',');
1683 if (!str) {
1684 printk(KERN_ERR "need port name after brl=\n");
1685 return 1;
1686 }
1687 *(str++) = 0;
1688 }
1689#endif
1690
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001691 /*
1692 * Decode str into name, index, options.
1693 */
1694 if (str[0] >= '0' && str[0] <= '9') {
Yinghai Lueaa944a2007-07-15 23:37:27 -07001695 strcpy(buf, "ttyS");
1696 strncpy(buf + 4, str, sizeof(buf) - 5);
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001697 } else {
Yinghai Lueaa944a2007-07-15 23:37:27 -07001698 strncpy(buf, str, sizeof(buf) - 1);
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001699 }
Yinghai Lueaa944a2007-07-15 23:37:27 -07001700 buf[sizeof(buf) - 1] = 0;
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001701 if ((options = strchr(str, ',')) != NULL)
1702 *(options++) = 0;
1703#ifdef __sparc__
1704 if (!strcmp(str, "ttya"))
Yinghai Lueaa944a2007-07-15 23:37:27 -07001705 strcpy(buf, "ttyS0");
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001706 if (!strcmp(str, "ttyb"))
Yinghai Lueaa944a2007-07-15 23:37:27 -07001707 strcpy(buf, "ttyS1");
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001708#endif
Yinghai Lueaa944a2007-07-15 23:37:27 -07001709 for (s = buf; *s; s++)
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001710 if ((*s >= '0' && *s <= '9') || *s == ',')
1711 break;
1712 idx = simple_strtoul(s, NULL, 10);
1713 *s = 0;
1714
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001715 __add_preferred_console(buf, idx, options, brl_options);
Markus Armbruster9e124fe2008-05-26 23:31:07 +01001716 console_set_on_cmdline = 1;
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001717 return 1;
1718}
1719__setup("console=", console_setup);
1720
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721/**
Matt Mackall3c0547b2005-05-16 21:53:47 -07001722 * add_preferred_console - add a device to the list of preferred consoles.
Martin Waitzddad86c2005-11-13 16:08:14 -08001723 * @name: device name
1724 * @idx: device index
1725 * @options: options for this console
Matt Mackall3c0547b2005-05-16 21:53:47 -07001726 *
1727 * The last preferred console added will be used for kernel messages
1728 * and stdin/out/err for init. Normally this is used by console_setup
1729 * above to handle user-supplied console arguments; however it can also
1730 * be used by arch-specific code either to override the user or more
1731 * commonly to provide a default console (ie from PROM variables) when
1732 * the user has not supplied one.
1733 */
David S. Millerfb445ee2007-12-29 01:19:49 -08001734int add_preferred_console(char *name, int idx, char *options)
Matt Mackall3c0547b2005-05-16 21:53:47 -07001735{
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001736 return __add_preferred_console(name, idx, options, NULL);
Matt Mackall3c0547b2005-05-16 21:53:47 -07001737}
1738
Daniel Ritzb6b1d872007-08-03 16:07:43 +02001739int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
Yinghai Lu18a8bd92007-07-15 23:37:59 -07001740{
1741 struct console_cmdline *c;
1742 int i;
1743
1744 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
1745 if (strcmp(console_cmdline[i].name, name) == 0 &&
1746 console_cmdline[i].index == idx) {
1747 c = &console_cmdline[i];
Markus Armbrusterf7352952008-04-30 00:54:52 -07001748 strlcpy(c->name, name_new, sizeof(c->name));
Yinghai Lu18a8bd92007-07-15 23:37:59 -07001749 c->name[sizeof(c->name) - 1] = 0;
1750 c->options = options;
1751 c->index = idx_new;
1752 return i;
1753 }
1754 /* not found */
1755 return -1;
1756}
1757
Rusty Russell2329abf2012-01-13 09:32:18 +10301758bool console_suspend_enabled = 1;
Andres Salomon8f4ce8c2007-10-18 03:04:50 -07001759EXPORT_SYMBOL(console_suspend_enabled);
1760
1761static int __init console_suspend_disable(char *str)
1762{
1763 console_suspend_enabled = 0;
1764 return 1;
1765}
1766__setup("no_console_suspend", console_suspend_disable);
Yanmin Zhang134620f2011-10-31 17:11:27 -07001767module_param_named(console_suspend, console_suspend_enabled,
1768 bool, S_IRUGO | S_IWUSR);
1769MODULE_PARM_DESC(console_suspend, "suspend console during suspend"
1770 " and hibernate operations");
Andres Salomon8f4ce8c2007-10-18 03:04:50 -07001771
Matt Mackall3c0547b2005-05-16 21:53:47 -07001772/**
Linus Torvalds557240b2006-06-19 18:16:01 -07001773 * suspend_console - suspend the console subsystem
1774 *
1775 * This disables printk() while we go into suspend states
1776 */
1777void suspend_console(void)
1778{
Andres Salomon8f4ce8c2007-10-18 03:04:50 -07001779 if (!console_suspend_enabled)
1780 return;
Pavel Machek0d630812008-07-23 21:28:32 -07001781 printk("Suspending console(s) (use no_console_suspend to debug)\n");
Torben Hohnac751ef2011-01-25 15:07:35 -08001782 console_lock();
Linus Torvalds557240b2006-06-19 18:16:01 -07001783 console_suspended = 1;
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001784 up(&console_sem);
Linus Torvalds557240b2006-06-19 18:16:01 -07001785}
1786
1787void resume_console(void)
1788{
Andres Salomon8f4ce8c2007-10-18 03:04:50 -07001789 if (!console_suspend_enabled)
1790 return;
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001791 down(&console_sem);
Linus Torvalds557240b2006-06-19 18:16:01 -07001792 console_suspended = 0;
Torben Hohnac751ef2011-01-25 15:07:35 -08001793 console_unlock();
Linus Torvalds557240b2006-06-19 18:16:01 -07001794}
1795
1796/**
Kevin Cernekee034260d2010-06-03 22:11:25 -07001797 * console_cpu_notify - print deferred console messages after CPU hotplug
1798 * @self: notifier struct
1799 * @action: CPU hotplug event
1800 * @hcpu: unused
1801 *
1802 * If printk() is called from a CPU that is not online yet, the messages
1803 * will be spooled but will not show up on the console. This function is
1804 * called when a new CPU comes online (or fails to come up), and ensures
1805 * that any such output gets printed.
1806 */
1807static int __cpuinit console_cpu_notify(struct notifier_block *self,
1808 unsigned long action, void *hcpu)
1809{
1810 switch (action) {
1811 case CPU_ONLINE:
1812 case CPU_DEAD:
1813 case CPU_DYING:
1814 case CPU_DOWN_FAILED:
1815 case CPU_UP_CANCELED:
Torben Hohnac751ef2011-01-25 15:07:35 -08001816 console_lock();
1817 console_unlock();
Kevin Cernekee034260d2010-06-03 22:11:25 -07001818 }
1819 return NOTIFY_OK;
1820}
1821
1822/**
Torben Hohnac751ef2011-01-25 15:07:35 -08001823 * console_lock - lock the console system for exclusive use.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001824 *
Torben Hohnac751ef2011-01-25 15:07:35 -08001825 * Acquires a lock which guarantees that the caller has
Linus Torvalds1da177e2005-04-16 15:20:36 -07001826 * exclusive access to the console system and the console_drivers list.
1827 *
1828 * Can sleep, returns nothing.
1829 */
Torben Hohnac751ef2011-01-25 15:07:35 -08001830void console_lock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831{
Eric Sesterhenn8abd8e22006-04-01 01:21:17 +02001832 BUG_ON(in_interrupt());
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833 down(&console_sem);
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001834 if (console_suspended)
1835 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836 console_locked = 1;
1837 console_may_schedule = 1;
1838}
Torben Hohnac751ef2011-01-25 15:07:35 -08001839EXPORT_SYMBOL(console_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001840
Torben Hohnac751ef2011-01-25 15:07:35 -08001841/**
1842 * console_trylock - try to lock the console system for exclusive use.
1843 *
1844 * Tried to acquire a lock which guarantees that the caller has
1845 * exclusive access to the console system and the console_drivers list.
1846 *
1847 * returns 1 on success, and 0 on failure to acquire the lock.
1848 */
1849int console_trylock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001850{
1851 if (down_trylock(&console_sem))
Torben Hohnac751ef2011-01-25 15:07:35 -08001852 return 0;
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001853 if (console_suspended) {
1854 up(&console_sem);
Torben Hohnac751ef2011-01-25 15:07:35 -08001855 return 0;
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001856 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001857 console_locked = 1;
1858 console_may_schedule = 0;
Torben Hohnac751ef2011-01-25 15:07:35 -08001859 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001860}
Torben Hohnac751ef2011-01-25 15:07:35 -08001861EXPORT_SYMBOL(console_trylock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862
1863int is_console_locked(void)
1864{
1865 return console_locked;
1866}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867
Peter Zijlstra3ccf3e82012-02-27 10:47:00 +01001868/*
Kay Sievers7ff95542012-05-03 02:29:13 +02001869 * Delayed printk version, for scheduler-internal messages:
Peter Zijlstra3ccf3e82012-02-27 10:47:00 +01001870 */
1871#define PRINTK_BUF_SIZE 512
1872
1873#define PRINTK_PENDING_WAKEUP 0x01
1874#define PRINTK_PENDING_SCHED 0x02
1875
Peter Zijlstrab845b512008-08-08 21:47:09 +02001876static DEFINE_PER_CPU(int, printk_pending);
Peter Zijlstra3ccf3e82012-02-27 10:47:00 +01001877static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
Peter Zijlstrab845b512008-08-08 21:47:09 +02001878
1879void printk_tick(void)
1880{
Eric Dumazet40dc11f2010-11-26 17:22:16 +01001881 if (__this_cpu_read(printk_pending)) {
Peter Zijlstra3ccf3e82012-02-27 10:47:00 +01001882 int pending = __this_cpu_xchg(printk_pending, 0);
1883 if (pending & PRINTK_PENDING_SCHED) {
1884 char *buf = __get_cpu_var(printk_sched_buf);
1885 printk(KERN_WARNING "[sched_delayed] %s", buf);
1886 }
1887 if (pending & PRINTK_PENDING_WAKEUP)
1888 wake_up_interruptible(&log_wait);
Peter Zijlstrab845b512008-08-08 21:47:09 +02001889 }
1890}
1891
1892int printk_needs_cpu(int cpu)
1893{
Eric Dumazet40dc11f2010-11-26 17:22:16 +01001894 if (cpu_is_offline(cpu))
Heiko Carstens61ab25442010-11-26 13:00:59 +01001895 printk_tick();
Eric Dumazet40dc11f2010-11-26 17:22:16 +01001896 return __this_cpu_read(printk_pending);
Peter Zijlstrab845b512008-08-08 21:47:09 +02001897}
1898
Kirill Korotaeve3e8a752007-02-10 01:46:19 -08001899void wake_up_klogd(void)
1900{
Peter Zijlstrab845b512008-08-08 21:47:09 +02001901 if (waitqueue_active(&log_wait))
Peter Zijlstra3ccf3e82012-02-27 10:47:00 +01001902 this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
Kirill Korotaeve3e8a752007-02-10 01:46:19 -08001903}
1904
Kay Sievers7ff95542012-05-03 02:29:13 +02001905/* the next printk record to write to the console */
1906static u64 console_seq;
1907static u32 console_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07001908static enum log_flags console_prev;
Kay Sievers7ff95542012-05-03 02:29:13 +02001909
Linus Torvalds1da177e2005-04-16 15:20:36 -07001910/**
Torben Hohnac751ef2011-01-25 15:07:35 -08001911 * console_unlock - unlock the console system
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912 *
Torben Hohnac751ef2011-01-25 15:07:35 -08001913 * Releases the console_lock which the caller holds on the console system
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914 * and the console driver list.
1915 *
Torben Hohnac751ef2011-01-25 15:07:35 -08001916 * While the console_lock was held, console output may have been buffered
1917 * by printk(). If this is the case, console_unlock(); emits
1918 * the output prior to releasing the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919 *
Kay Sievers7f3a7812012-05-09 01:37:51 +02001920 * If there is output waiting, we wake /dev/kmsg and syslog() users.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001921 *
Torben Hohnac751ef2011-01-25 15:07:35 -08001922 * console_unlock(); may be called from any context.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001923 */
Torben Hohnac751ef2011-01-25 15:07:35 -08001924void console_unlock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001925{
Kay Sievers084681d2012-06-28 09:38:53 +02001926 static char text[LOG_LINE_MAX];
Kay Sievers7ff95542012-05-03 02:29:13 +02001927 static u64 seen_seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001928 unsigned long flags;
Kay Sievers7ff95542012-05-03 02:29:13 +02001929 bool wake_klogd = false;
1930 bool retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001931
Linus Torvalds557240b2006-06-19 18:16:01 -07001932 if (console_suspended) {
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001933 up(&console_sem);
Linus Torvalds557240b2006-06-19 18:16:01 -07001934 return;
1935 }
Antonino A. Daplas78944e52006-08-05 12:14:16 -07001936
1937 console_may_schedule = 0;
1938
Kay Sievers084681d2012-06-28 09:38:53 +02001939 /* flush buffered message fragment immediately to console */
1940 raw_spin_lock_irqsave(&logbuf_lock, flags);
1941 if (cont.len && (cont.cons < cont.len || cont.flushed)) {
1942 size_t len;
1943
1944 len = cont_print_text(text, sizeof(text));
1945 raw_spin_unlock(&logbuf_lock);
1946 stop_critical_timings();
1947 call_console_drivers(cont.level, text, len);
1948 start_critical_timings();
1949 local_irq_restore(flags);
1950 } else
1951 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
1952
Peter Zijlstra4f2a8d32011-06-22 11:20:09 +02001953again:
Kay Sievers7ff95542012-05-03 02:29:13 +02001954 for (;;) {
1955 struct log *msg;
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001956 size_t len;
Kay Sievers7ff95542012-05-03 02:29:13 +02001957 int level;
1958
Thomas Gleixner07354eb2009-07-25 17:50:36 +02001959 raw_spin_lock_irqsave(&logbuf_lock, flags);
Kay Sievers7ff95542012-05-03 02:29:13 +02001960 if (seen_seq != log_next_seq) {
1961 wake_klogd = true;
1962 seen_seq = log_next_seq;
1963 }
1964
1965 if (console_seq < log_first_seq) {
1966 /* messages are gone, move to first one */
1967 console_seq = log_first_seq;
1968 console_idx = log_first_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07001969 console_prev = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001970 }
Kay Sievers084681d2012-06-28 09:38:53 +02001971skip:
Kay Sievers7ff95542012-05-03 02:29:13 +02001972 if (console_seq == log_next_seq)
1973 break;
1974
1975 msg = log_from_idx(console_idx);
Kay Sievers084681d2012-06-28 09:38:53 +02001976 if (msg->flags & LOG_NOCONS) {
1977 /*
1978 * Skip record we have buffered and already printed
1979 * directly to the console when we received it.
1980 */
1981 console_idx = log_next(console_idx);
1982 console_seq++;
Kay Sievers68b65072012-07-06 09:50:09 -07001983 /*
1984 * We will get here again when we register a new
1985 * CON_PRINTBUFFER console. Clear the flag so we
1986 * will properly dump everything later.
1987 */
1988 msg->flags &= ~LOG_NOCONS;
Kay Sievers084681d2012-06-28 09:38:53 +02001989 goto skip;
1990 }
Kay Sievers649e6ee2012-05-10 04:30:45 +02001991
Kay Sievers084681d2012-06-28 09:38:53 +02001992 level = msg->level;
Kay Sievers5becfb12012-07-09 12:15:42 -07001993 len = msg_print_text(msg, console_prev, false,
1994 text, sizeof(text));
Kay Sievers7ff95542012-05-03 02:29:13 +02001995 console_idx = log_next(console_idx);
1996 console_seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07001997 console_prev = msg->flags;
Thomas Gleixner07354eb2009-07-25 17:50:36 +02001998 raw_spin_unlock(&logbuf_lock);
Kay Sievers7ff95542012-05-03 02:29:13 +02001999
Steven Rostedt81d68a92008-05-12 21:20:42 +02002000 stop_critical_timings(); /* don't trace print latency */
Kay Sievers7ff95542012-05-03 02:29:13 +02002001 call_console_drivers(level, text, len);
Steven Rostedt81d68a92008-05-12 21:20:42 +02002002 start_critical_timings();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002003 local_irq_restore(flags);
2004 }
2005 console_locked = 0;
Feng Tangfe3d8ad2011-03-22 16:34:21 -07002006
2007 /* Release the exclusive_console once it is used */
2008 if (unlikely(exclusive_console))
2009 exclusive_console = NULL;
2010
Thomas Gleixner07354eb2009-07-25 17:50:36 +02002011 raw_spin_unlock(&logbuf_lock);
Peter Zijlstra4f2a8d32011-06-22 11:20:09 +02002012
Peter Zijlstra0b5e1c52011-06-07 11:15:33 +02002013 up(&console_sem);
Peter Zijlstra4f2a8d32011-06-22 11:20:09 +02002014
2015 /*
2016 * Someone could have filled up the buffer again, so re-check if there's
2017 * something to flush. In case we cannot trylock the console_sem again,
2018 * there's a new owner and the console_unlock() from them will do the
2019 * flush, no worries.
2020 */
Thomas Gleixner07354eb2009-07-25 17:50:36 +02002021 raw_spin_lock(&logbuf_lock);
Kay Sievers7ff95542012-05-03 02:29:13 +02002022 retry = console_seq != log_next_seq;
Peter Zijlstra09dc3cf2011-12-08 14:34:13 -08002023 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2024
Peter Zijlstra4f2a8d32011-06-22 11:20:09 +02002025 if (retry && console_trylock())
2026 goto again;
2027
Kirill Korotaeve3e8a752007-02-10 01:46:19 -08002028 if (wake_klogd)
2029 wake_up_klogd();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030}
Torben Hohnac751ef2011-01-25 15:07:35 -08002031EXPORT_SYMBOL(console_unlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002032
Martin Waitzddad86c2005-11-13 16:08:14 -08002033/**
2034 * console_conditional_schedule - yield the CPU if required
Linus Torvalds1da177e2005-04-16 15:20:36 -07002035 *
2036 * If the console code is currently allowed to sleep, and
2037 * if this CPU should yield the CPU to another task, do
2038 * so here.
2039 *
Torben Hohnac751ef2011-01-25 15:07:35 -08002040 * Must be called within console_lock();.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002041 */
2042void __sched console_conditional_schedule(void)
2043{
2044 if (console_may_schedule)
2045 cond_resched();
2046}
2047EXPORT_SYMBOL(console_conditional_schedule);
2048
Linus Torvalds1da177e2005-04-16 15:20:36 -07002049void console_unblank(void)
2050{
2051 struct console *c;
2052
2053 /*
2054 * console_unblank can no longer be called in interrupt context unless
2055 * oops_in_progress is set to 1..
2056 */
2057 if (oops_in_progress) {
2058 if (down_trylock(&console_sem) != 0)
2059 return;
2060 } else
Torben Hohnac751ef2011-01-25 15:07:35 -08002061 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002062
2063 console_locked = 1;
2064 console_may_schedule = 0;
Robin Getz4d091612009-07-01 21:08:37 -04002065 for_each_console(c)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002066 if ((c->flags & CON_ENABLED) && c->unblank)
2067 c->unblank();
Torben Hohnac751ef2011-01-25 15:07:35 -08002068 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002069}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070
2071/*
2072 * Return the console tty driver structure and its associated index
2073 */
2074struct tty_driver *console_device(int *index)
2075{
2076 struct console *c;
2077 struct tty_driver *driver = NULL;
2078
Torben Hohnac751ef2011-01-25 15:07:35 -08002079 console_lock();
Robin Getz4d091612009-07-01 21:08:37 -04002080 for_each_console(c) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081 if (!c->device)
2082 continue;
2083 driver = c->device(c, index);
2084 if (driver)
2085 break;
2086 }
Torben Hohnac751ef2011-01-25 15:07:35 -08002087 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002088 return driver;
2089}
2090
2091/*
2092 * Prevent further output on the passed console device so that (for example)
2093 * serial drivers can disable console output before suspending a port, and can
2094 * re-enable output afterwards.
2095 */
2096void console_stop(struct console *console)
2097{
Torben Hohnac751ef2011-01-25 15:07:35 -08002098 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002099 console->flags &= ~CON_ENABLED;
Torben Hohnac751ef2011-01-25 15:07:35 -08002100 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002101}
2102EXPORT_SYMBOL(console_stop);
2103
2104void console_start(struct console *console)
2105{
Torben Hohnac751ef2011-01-25 15:07:35 -08002106 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002107 console->flags |= CON_ENABLED;
Torben Hohnac751ef2011-01-25 15:07:35 -08002108 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109}
2110EXPORT_SYMBOL(console_start);
2111
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -07002112static int __read_mostly keep_bootcon;
2113
2114static int __init keep_bootcon_setup(char *str)
2115{
2116 keep_bootcon = 1;
2117 printk(KERN_INFO "debug: skip boot console de-registration.\n");
2118
2119 return 0;
2120}
2121
2122early_param("keep_bootcon", keep_bootcon_setup);
2123
Linus Torvalds1da177e2005-04-16 15:20:36 -07002124/*
2125 * The console driver calls this routine during kernel initialization
2126 * to register the console printing procedure with printk() and to
2127 * print any messages that were printed by the kernel before the
2128 * console driver was initialized.
Robin Getz4d091612009-07-01 21:08:37 -04002129 *
2130 * This can happen pretty early during the boot process (because of
2131 * early_printk) - sometimes before setup_arch() completes - be careful
2132 * of what kernel features are used - they may not be initialised yet.
2133 *
2134 * There are two types of consoles - bootconsoles (early_printk) and
2135 * "real" consoles (everything which is not a bootconsole) which are
2136 * handled differently.
2137 * - Any number of bootconsoles can be registered at any time.
2138 * - As soon as a "real" console is registered, all bootconsoles
2139 * will be unregistered automatically.
2140 * - Once a "real" console is registered, any attempt to register a
2141 * bootconsoles will be rejected
Linus Torvalds1da177e2005-04-16 15:20:36 -07002142 */
Robin Getz4d091612009-07-01 21:08:37 -04002143void register_console(struct console *newcon)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002144{
Jesper Juhl40dc5652005-10-30 15:02:46 -08002145 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 unsigned long flags;
Robin Getz4d091612009-07-01 21:08:37 -04002147 struct console *bcon = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002148
Robin Getz4d091612009-07-01 21:08:37 -04002149 /*
2150 * before we register a new CON_BOOT console, make sure we don't
2151 * already have a valid console
2152 */
2153 if (console_drivers && newcon->flags & CON_BOOT) {
2154 /* find the last or real console */
2155 for_each_console(bcon) {
2156 if (!(bcon->flags & CON_BOOT)) {
2157 printk(KERN_INFO "Too late to register bootconsole %s%d\n",
2158 newcon->name, newcon->index);
2159 return;
2160 }
2161 }
Gerd Hoffmann69331af2007-05-08 00:26:49 -07002162 }
2163
Robin Getz4d091612009-07-01 21:08:37 -04002164 if (console_drivers && console_drivers->flags & CON_BOOT)
2165 bcon = console_drivers;
2166
2167 if (preferred_console < 0 || bcon || !console_drivers)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002168 preferred_console = selected_console;
2169
Robin Getz4d091612009-07-01 21:08:37 -04002170 if (newcon->early_setup)
2171 newcon->early_setup();
Yinghai Lu18a8bd92007-07-15 23:37:59 -07002172
Linus Torvalds1da177e2005-04-16 15:20:36 -07002173 /*
2174 * See if we want to use this console driver. If we
2175 * didn't select a console we take the first one
2176 * that registers here.
2177 */
2178 if (preferred_console < 0) {
Robin Getz4d091612009-07-01 21:08:37 -04002179 if (newcon->index < 0)
2180 newcon->index = 0;
2181 if (newcon->setup == NULL ||
2182 newcon->setup(newcon, NULL) == 0) {
2183 newcon->flags |= CON_ENABLED;
2184 if (newcon->device) {
2185 newcon->flags |= CON_CONSDEV;
Jan Kiszkacd3a1b82008-05-12 21:21:04 +02002186 preferred_console = 0;
2187 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002188 }
2189 }
2190
2191 /*
2192 * See if this console matches one we selected on
2193 * the command line.
2194 */
Jesper Juhl40dc5652005-10-30 15:02:46 -08002195 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
2196 i++) {
Robin Getz4d091612009-07-01 21:08:37 -04002197 if (strcmp(console_cmdline[i].name, newcon->name) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002198 continue;
Robin Getz4d091612009-07-01 21:08:37 -04002199 if (newcon->index >= 0 &&
2200 newcon->index != console_cmdline[i].index)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201 continue;
Robin Getz4d091612009-07-01 21:08:37 -04002202 if (newcon->index < 0)
2203 newcon->index = console_cmdline[i].index;
Samuel Thibaultf7511d52008-04-30 00:54:51 -07002204#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
2205 if (console_cmdline[i].brl_options) {
Robin Getz4d091612009-07-01 21:08:37 -04002206 newcon->flags |= CON_BRL;
2207 braille_register_console(newcon,
Samuel Thibaultf7511d52008-04-30 00:54:51 -07002208 console_cmdline[i].index,
2209 console_cmdline[i].options,
2210 console_cmdline[i].brl_options);
2211 return;
2212 }
2213#endif
Robin Getz4d091612009-07-01 21:08:37 -04002214 if (newcon->setup &&
2215 newcon->setup(newcon, console_cmdline[i].options) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002216 break;
Robin Getz4d091612009-07-01 21:08:37 -04002217 newcon->flags |= CON_ENABLED;
2218 newcon->index = console_cmdline[i].index;
Greg Edwardsab4af032005-06-23 00:09:05 -07002219 if (i == selected_console) {
Robin Getz4d091612009-07-01 21:08:37 -04002220 newcon->flags |= CON_CONSDEV;
Greg Edwardsab4af032005-06-23 00:09:05 -07002221 preferred_console = selected_console;
2222 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002223 break;
2224 }
2225
Robin Getz4d091612009-07-01 21:08:37 -04002226 if (!(newcon->flags & CON_ENABLED))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002227 return;
2228
Robin Getz8259cf42009-07-09 13:08:37 -04002229 /*
2230 * If we have a bootconsole, and are switching to a real console,
2231 * don't print everything out again, since when the boot console, and
2232 * the real console are the same physical device, it's annoying to
2233 * see the beginning boot messages twice
2234 */
2235 if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
Robin Getz4d091612009-07-01 21:08:37 -04002236 newcon->flags &= ~CON_PRINTBUFFER;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002237
2238 /*
2239 * Put this console in the list - keep the
2240 * preferred driver at the head of the list.
2241 */
Torben Hohnac751ef2011-01-25 15:07:35 -08002242 console_lock();
Robin Getz4d091612009-07-01 21:08:37 -04002243 if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
2244 newcon->next = console_drivers;
2245 console_drivers = newcon;
2246 if (newcon->next)
2247 newcon->next->flags &= ~CON_CONSDEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002248 } else {
Robin Getz4d091612009-07-01 21:08:37 -04002249 newcon->next = console_drivers->next;
2250 console_drivers->next = newcon;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002251 }
Robin Getz4d091612009-07-01 21:08:37 -04002252 if (newcon->flags & CON_PRINTBUFFER) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002253 /*
Torben Hohnac751ef2011-01-25 15:07:35 -08002254 * console_unlock(); will print out the buffered messages
Linus Torvalds1da177e2005-04-16 15:20:36 -07002255 * for us.
2256 */
Thomas Gleixner07354eb2009-07-25 17:50:36 +02002257 raw_spin_lock_irqsave(&logbuf_lock, flags);
Kay Sievers7ff95542012-05-03 02:29:13 +02002258 console_seq = syslog_seq;
2259 console_idx = syslog_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07002260 console_prev = syslog_prev;
Thomas Gleixner07354eb2009-07-25 17:50:36 +02002261 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
Feng Tangfe3d8ad2011-03-22 16:34:21 -07002262 /*
2263 * We're about to replay the log buffer. Only do this to the
2264 * just-registered console to avoid excessive message spam to
2265 * the already-registered consoles.
2266 */
2267 exclusive_console = newcon;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002268 }
Torben Hohnac751ef2011-01-25 15:07:35 -08002269 console_unlock();
Kay Sieversfbc92a32010-12-01 18:51:05 +01002270 console_sysfs_notify();
Robin Getz8259cf42009-07-09 13:08:37 -04002271
2272 /*
2273 * By unregistering the bootconsoles after we enable the real console
2274 * we get the "console xxx enabled" message on all the consoles -
2275 * boot consoles, real consoles, etc - this is to ensure that end
2276 * users know there might be something in the kernel's log buffer that
2277 * went to the bootconsole (that they do not see on the real console)
2278 */
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -07002279 if (bcon &&
2280 ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
2281 !keep_bootcon) {
Robin Getz8259cf42009-07-09 13:08:37 -04002282 /* we need to iterate through twice, to make sure we print
2283 * everything out, before we unregister the console(s)
2284 */
2285 printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n",
2286 newcon->name, newcon->index);
2287 for_each_console(bcon)
2288 if (bcon->flags & CON_BOOT)
2289 unregister_console(bcon);
2290 } else {
2291 printk(KERN_INFO "%sconsole [%s%d] enabled\n",
2292 (newcon->flags & CON_BOOT) ? "boot" : "" ,
2293 newcon->name, newcon->index);
2294 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002295}
2296EXPORT_SYMBOL(register_console);
2297
Jesper Juhl40dc5652005-10-30 15:02:46 -08002298int unregister_console(struct console *console)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002299{
Jesper Juhl40dc5652005-10-30 15:02:46 -08002300 struct console *a, *b;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002301 int res = 1;
2302
Samuel Thibaultf7511d52008-04-30 00:54:51 -07002303#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
2304 if (console->flags & CON_BRL)
2305 return braille_unregister_console(console);
2306#endif
2307
Torben Hohnac751ef2011-01-25 15:07:35 -08002308 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002309 if (console_drivers == console) {
2310 console_drivers=console->next;
2311 res = 0;
Benjamin Herrenschmidte9b15b52005-11-23 13:37:44 -08002312 } else if (console_drivers) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002313 for (a=console_drivers->next, b=console_drivers ;
2314 a; b=a, a=b->next) {
2315 if (a == console) {
2316 b->next = a->next;
2317 res = 0;
2318 break;
Jesper Juhl40dc5652005-10-30 15:02:46 -08002319 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002320 }
2321 }
Jesper Juhl40dc5652005-10-30 15:02:46 -08002322
Gerd Hoffmann69331af2007-05-08 00:26:49 -07002323 /*
Greg Edwardsab4af032005-06-23 00:09:05 -07002324 * If this isn't the last console and it has CON_CONSDEV set, we
2325 * need to set it on the next preferred console.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002326 */
Gerd Hoffmann69331af2007-05-08 00:26:49 -07002327 if (console_drivers != NULL && console->flags & CON_CONSDEV)
Greg Edwardsab4af032005-06-23 00:09:05 -07002328 console_drivers->flags |= CON_CONSDEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002329
Torben Hohnac751ef2011-01-25 15:07:35 -08002330 console_unlock();
Kay Sieversfbc92a32010-12-01 18:51:05 +01002331 console_sysfs_notify();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002332 return res;
2333}
2334EXPORT_SYMBOL(unregister_console);
Matt Mackalld59745c2005-05-01 08:59:02 -07002335
Kevin Cernekee034260d2010-06-03 22:11:25 -07002336static int __init printk_late_init(void)
Robin Getz0c5564b2007-08-20 15:22:47 -04002337{
Robin Getz4d091612009-07-01 21:08:37 -04002338 struct console *con;
2339
2340 for_each_console(con) {
Nishanth Aravamudan4c30c6f2011-08-25 15:59:11 -07002341 if (!keep_bootcon && con->flags & CON_BOOT) {
Robin Getzcb00e992007-08-21 23:14:58 -04002342 printk(KERN_INFO "turn off boot console %s%d\n",
Robin Getz4d091612009-07-01 21:08:37 -04002343 con->name, con->index);
Sonic Zhang42c2c8c2009-08-06 15:58:11 -07002344 unregister_console(con);
Robin Getzcb00e992007-08-21 23:14:58 -04002345 }
Robin Getz0c5564b2007-08-20 15:22:47 -04002346 }
Kevin Cernekee034260d2010-06-03 22:11:25 -07002347 hotcpu_notifier(console_cpu_notify, 0);
Robin Getz0c5564b2007-08-20 15:22:47 -04002348 return 0;
2349}
Kevin Cernekee034260d2010-06-03 22:11:25 -07002350late_initcall(printk_late_init);
Robin Getz0c5564b2007-08-20 15:22:47 -04002351
Joe Perches7ef3d2f2008-02-08 04:21:25 -08002352#if defined CONFIG_PRINTK
Dave Young717115e2008-07-25 01:45:58 -07002353
Peter Zijlstra600e1452012-03-15 12:35:37 +01002354int printk_sched(const char *fmt, ...)
2355{
2356 unsigned long flags;
2357 va_list args;
2358 char *buf;
2359 int r;
2360
2361 local_irq_save(flags);
2362 buf = __get_cpu_var(printk_sched_buf);
2363
2364 va_start(args, fmt);
2365 r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
2366 va_end(args);
2367
2368 __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
2369 local_irq_restore(flags);
2370
2371 return r;
2372}
2373
Linus Torvalds1da177e2005-04-16 15:20:36 -07002374/*
2375 * printk rate limiting, lifted from the networking subsystem.
2376 *
Uwe Kleine-König641de9d2008-07-29 22:33:38 -07002377 * This enforces a rate limit: not more than 10 kernel messages
2378 * every 5s to make a denial-of-service attack impossible.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002379 */
Uwe Kleine-König641de9d2008-07-29 22:33:38 -07002380DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
2381
Christian Borntraeger5c828712009-10-23 14:58:11 +02002382int __printk_ratelimit(const char *func)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002383{
Christian Borntraeger5c828712009-10-23 14:58:11 +02002384 return ___ratelimit(&printk_ratelimit_state, func);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002385}
Christian Borntraeger5c828712009-10-23 14:58:11 +02002386EXPORT_SYMBOL(__printk_ratelimit);
Andrew Mortonf46c4832006-11-02 22:07:16 -08002387
2388/**
2389 * printk_timed_ratelimit - caller-controlled printk ratelimiting
2390 * @caller_jiffies: pointer to caller's state
2391 * @interval_msecs: minimum interval between prints
2392 *
2393 * printk_timed_ratelimit() returns true if more than @interval_msecs
2394 * milliseconds have elapsed since the last time printk_timed_ratelimit()
2395 * returned true.
2396 */
2397bool printk_timed_ratelimit(unsigned long *caller_jiffies,
2398 unsigned int interval_msecs)
2399{
Guillaume Knispelf2d28a22009-03-17 16:18:42 +01002400 if (*caller_jiffies == 0
2401 || !time_in_range(jiffies, *caller_jiffies,
2402 *caller_jiffies
2403 + msecs_to_jiffies(interval_msecs))) {
2404 *caller_jiffies = jiffies;
Andrew Mortonf46c4832006-11-02 22:07:16 -08002405 return true;
2406 }
2407 return false;
2408}
2409EXPORT_SYMBOL(printk_timed_ratelimit);
Simon Kagstrom456b5652009-10-16 14:09:18 +02002410
2411static DEFINE_SPINLOCK(dump_list_lock);
2412static LIST_HEAD(dump_list);
2413
2414/**
2415 * kmsg_dump_register - register a kernel log dumper.
Randy Dunlap64855362009-12-17 15:27:27 -08002416 * @dumper: pointer to the kmsg_dumper structure
Simon Kagstrom456b5652009-10-16 14:09:18 +02002417 *
2418 * Adds a kernel log dumper to the system. The dump callback in the
2419 * structure will be called when the kernel oopses or panics and must be
2420 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
2421 */
2422int kmsg_dump_register(struct kmsg_dumper *dumper)
2423{
2424 unsigned long flags;
2425 int err = -EBUSY;
2426
2427 /* The dump callback needs to be set */
2428 if (!dumper->dump)
2429 return -EINVAL;
2430
2431 spin_lock_irqsave(&dump_list_lock, flags);
2432 /* Don't allow registering multiple times */
2433 if (!dumper->registered) {
2434 dumper->registered = 1;
Huang Yingfb842b02011-01-12 16:59:43 -08002435 list_add_tail_rcu(&dumper->list, &dump_list);
Simon Kagstrom456b5652009-10-16 14:09:18 +02002436 err = 0;
2437 }
2438 spin_unlock_irqrestore(&dump_list_lock, flags);
2439
2440 return err;
2441}
2442EXPORT_SYMBOL_GPL(kmsg_dump_register);
2443
2444/**
2445 * kmsg_dump_unregister - unregister a kmsg dumper.
Randy Dunlap64855362009-12-17 15:27:27 -08002446 * @dumper: pointer to the kmsg_dumper structure
Simon Kagstrom456b5652009-10-16 14:09:18 +02002447 *
2448 * Removes a dump device from the system. Returns zero on success and
2449 * %-EINVAL otherwise.
2450 */
2451int kmsg_dump_unregister(struct kmsg_dumper *dumper)
2452{
2453 unsigned long flags;
2454 int err = -EINVAL;
2455
2456 spin_lock_irqsave(&dump_list_lock, flags);
2457 if (dumper->registered) {
2458 dumper->registered = 0;
Huang Yingfb842b02011-01-12 16:59:43 -08002459 list_del_rcu(&dumper->list);
Simon Kagstrom456b5652009-10-16 14:09:18 +02002460 err = 0;
2461 }
2462 spin_unlock_irqrestore(&dump_list_lock, flags);
Huang Yingfb842b02011-01-12 16:59:43 -08002463 synchronize_rcu();
Simon Kagstrom456b5652009-10-16 14:09:18 +02002464
2465 return err;
2466}
2467EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
2468
Kay Sievers7ff95542012-05-03 02:29:13 +02002469static bool always_kmsg_dump;
2470module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
2471
Simon Kagstrom456b5652009-10-16 14:09:18 +02002472/**
2473 * kmsg_dump - dump kernel log to kernel message dumpers.
2474 * @reason: the reason (oops, panic etc) for dumping
2475 *
Kay Sieverse2ae7152012-06-15 14:07:51 +02002476 * Call each of the registered dumper's dump() callback, which can
2477 * retrieve the kmsg records with kmsg_dump_get_line() or
2478 * kmsg_dump_get_buffer().
Simon Kagstrom456b5652009-10-16 14:09:18 +02002479 */
2480void kmsg_dump(enum kmsg_dump_reason reason)
2481{
Simon Kagstrom456b5652009-10-16 14:09:18 +02002482 struct kmsg_dumper *dumper;
Simon Kagstrom456b5652009-10-16 14:09:18 +02002483 unsigned long flags;
2484
Matthew Garrettc22ab332012-03-05 14:59:10 -08002485 if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
2486 return;
2487
Huang Yingfb842b02011-01-12 16:59:43 -08002488 rcu_read_lock();
Kay Sieverse2ae7152012-06-15 14:07:51 +02002489 list_for_each_entry_rcu(dumper, &dump_list, list) {
2490 if (dumper->max_reason && reason > dumper->max_reason)
2491 continue;
2492
2493 /* initialize iterator with data about the stored records */
2494 dumper->active = true;
2495
2496 raw_spin_lock_irqsave(&logbuf_lock, flags);
2497 dumper->cur_seq = clear_seq;
2498 dumper->cur_idx = clear_idx;
2499 dumper->next_seq = log_next_seq;
2500 dumper->next_idx = log_next_idx;
2501 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2502
2503 /* invoke dumper which will iterate over records */
2504 dumper->dump(dumper, reason);
2505
2506 /* reset iterator */
2507 dumper->active = false;
2508 }
Huang Yingfb842b02011-01-12 16:59:43 -08002509 rcu_read_unlock();
Simon Kagstrom456b5652009-10-16 14:09:18 +02002510}
Kay Sieverse2ae7152012-06-15 14:07:51 +02002511
2512/**
Anton Vorontsov533827c2012-07-20 17:28:07 -07002513 * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
2514 * @dumper: registered kmsg dumper
2515 * @syslog: include the "<4>" prefixes
2516 * @line: buffer to copy the line to
2517 * @size: maximum size of the buffer
2518 * @len: length of line placed into buffer
2519 *
2520 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2521 * record, and copy one record into the provided buffer.
2522 *
2523 * Consecutive calls will return the next available record moving
2524 * towards the end of the buffer with the youngest messages.
2525 *
2526 * A return value of FALSE indicates that there are no more records to
2527 * read.
2528 *
2529 * The function is similar to kmsg_dump_get_line(), but grabs no locks.
2530 */
2531bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
2532 char *line, size_t size, size_t *len)
2533{
2534 struct log *msg;
2535 size_t l = 0;
2536 bool ret = false;
2537
2538 if (!dumper->active)
2539 goto out;
2540
2541 if (dumper->cur_seq < log_first_seq) {
2542 /* messages are gone, move to first available one */
2543 dumper->cur_seq = log_first_seq;
2544 dumper->cur_idx = log_first_idx;
2545 }
2546
2547 /* last entry */
2548 if (dumper->cur_seq >= log_next_seq)
2549 goto out;
2550
2551 msg = log_from_idx(dumper->cur_idx);
2552 l = msg_print_text(msg, 0, syslog, line, size);
2553
2554 dumper->cur_idx = log_next(dumper->cur_idx);
2555 dumper->cur_seq++;
2556 ret = true;
2557out:
2558 if (len)
2559 *len = l;
2560 return ret;
2561}
2562
2563/**
Kay Sieverse2ae7152012-06-15 14:07:51 +02002564 * kmsg_dump_get_line - retrieve one kmsg log line
2565 * @dumper: registered kmsg dumper
2566 * @syslog: include the "<4>" prefixes
2567 * @line: buffer to copy the line to
2568 * @size: maximum size of the buffer
2569 * @len: length of line placed into buffer
2570 *
2571 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2572 * record, and copy one record into the provided buffer.
2573 *
2574 * Consecutive calls will return the next available record moving
2575 * towards the end of the buffer with the youngest messages.
2576 *
2577 * A return value of FALSE indicates that there are no more records to
2578 * read.
2579 */
2580bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
2581 char *line, size_t size, size_t *len)
2582{
2583 unsigned long flags;
Anton Vorontsov533827c2012-07-20 17:28:07 -07002584 bool ret;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002585
2586 raw_spin_lock_irqsave(&logbuf_lock, flags);
Anton Vorontsov533827c2012-07-20 17:28:07 -07002587 ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002588 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
Anton Vorontsov533827c2012-07-20 17:28:07 -07002589
Kay Sieverse2ae7152012-06-15 14:07:51 +02002590 return ret;
2591}
2592EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
2593
2594/**
2595 * kmsg_dump_get_buffer - copy kmsg log lines
2596 * @dumper: registered kmsg dumper
2597 * @syslog: include the "<4>" prefixes
Randy Dunlap4f0f4af2012-06-30 15:37:24 -07002598 * @buf: buffer to copy the line to
Kay Sieverse2ae7152012-06-15 14:07:51 +02002599 * @size: maximum size of the buffer
2600 * @len: length of line placed into buffer
2601 *
2602 * Start at the end of the kmsg buffer and fill the provided buffer
2603 * with as many of the the *youngest* kmsg records that fit into it.
2604 * If the buffer is large enough, all available kmsg records will be
2605 * copied with a single call.
2606 *
2607 * Consecutive calls will fill the buffer with the next block of
2608 * available older records, not including the earlier retrieved ones.
2609 *
2610 * A return value of FALSE indicates that there are no more records to
2611 * read.
2612 */
2613bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
2614 char *buf, size_t size, size_t *len)
2615{
2616 unsigned long flags;
2617 u64 seq;
2618 u32 idx;
2619 u64 next_seq;
2620 u32 next_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07002621 enum log_flags prev;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002622 size_t l = 0;
2623 bool ret = false;
2624
2625 if (!dumper->active)
2626 goto out;
2627
2628 raw_spin_lock_irqsave(&logbuf_lock, flags);
2629 if (dumper->cur_seq < log_first_seq) {
2630 /* messages are gone, move to first available one */
2631 dumper->cur_seq = log_first_seq;
2632 dumper->cur_idx = log_first_idx;
2633 }
2634
2635 /* last entry */
2636 if (dumper->cur_seq >= dumper->next_seq) {
2637 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2638 goto out;
2639 }
2640
2641 /* calculate length of entire buffer */
2642 seq = dumper->cur_seq;
2643 idx = dumper->cur_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07002644 prev = 0;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002645 while (seq < dumper->next_seq) {
2646 struct log *msg = log_from_idx(idx);
2647
Kay Sievers5becfb12012-07-09 12:15:42 -07002648 l += msg_print_text(msg, prev, true, NULL, 0);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002649 idx = log_next(idx);
2650 seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07002651 prev = msg->flags;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002652 }
2653
2654 /* move first record forward until length fits into the buffer */
2655 seq = dumper->cur_seq;
2656 idx = dumper->cur_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07002657 prev = 0;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002658 while (l > size && seq < dumper->next_seq) {
2659 struct log *msg = log_from_idx(idx);
2660
Kay Sievers5becfb12012-07-09 12:15:42 -07002661 l -= msg_print_text(msg, prev, true, NULL, 0);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002662 idx = log_next(idx);
2663 seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07002664 prev = msg->flags;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002665 }
2666
2667 /* last message in next interation */
2668 next_seq = seq;
2669 next_idx = idx;
2670
2671 l = 0;
Kay Sievers5becfb12012-07-09 12:15:42 -07002672 prev = 0;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002673 while (seq < dumper->next_seq) {
2674 struct log *msg = log_from_idx(idx);
2675
Kay Sievers5becfb12012-07-09 12:15:42 -07002676 l += msg_print_text(msg, prev, syslog, buf + l, size - l);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002677 idx = log_next(idx);
2678 seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07002679 prev = msg->flags;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002680 }
2681
2682 dumper->next_seq = next_seq;
2683 dumper->next_idx = next_idx;
2684 ret = true;
2685 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2686out:
2687 if (len)
2688 *len = l;
2689 return ret;
2690}
2691EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
2692
2693/**
Anton Vorontsov533827c2012-07-20 17:28:07 -07002694 * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
2695 * @dumper: registered kmsg dumper
2696 *
2697 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2698 * kmsg_dump_get_buffer() can be called again and used multiple
2699 * times within the same dumper.dump() callback.
2700 *
2701 * The function is similar to kmsg_dump_rewind(), but grabs no locks.
2702 */
2703void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
2704{
2705 dumper->cur_seq = clear_seq;
2706 dumper->cur_idx = clear_idx;
2707 dumper->next_seq = log_next_seq;
2708 dumper->next_idx = log_next_idx;
2709}
2710
2711/**
Kay Sieverse2ae7152012-06-15 14:07:51 +02002712 * kmsg_dump_rewind - reset the interator
2713 * @dumper: registered kmsg dumper
2714 *
2715 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2716 * kmsg_dump_get_buffer() can be called again and used multiple
2717 * times within the same dumper.dump() callback.
2718 */
2719void kmsg_dump_rewind(struct kmsg_dumper *dumper)
2720{
2721 unsigned long flags;
2722
2723 raw_spin_lock_irqsave(&logbuf_lock, flags);
Anton Vorontsov533827c2012-07-20 17:28:07 -07002724 kmsg_dump_rewind_nolock(dumper);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002725 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2726}
2727EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
Joe Perches7ef3d2f2008-02-08 04:21:25 -08002728#endif