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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>
Kent Overstreeta27bb332013-05-07 16:19:08 -070035#include <linux/aio.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070036#include <linux/syscalls.h>
Neil Horman04d491a2009-04-02 16:58:57 -070037#include <linux/kexec.h>
Jason Wesseld37d39a2010-05-20 21:04:27 -050038#include <linux/kdb.h>
Ingo Molnar3fff4c42009-09-22 16:18:09 +020039#include <linux/ratelimit.h>
Simon Kagstrom456b5652009-10-16 14:09:18 +020040#include <linux/kmsg_dump.h>
Kees Cook00234592010-02-03 15:36:43 -080041#include <linux/syslog.h>
Kevin Cernekee034260d2010-06-03 22:11:25 -070042#include <linux/cpu.h>
43#include <linux/notifier.h>
Huang Yingfb842b02011-01-12 16:59:43 -080044#include <linux/rculist.h>
Kay Sieverse11fea92012-05-03 02:29:41 +020045#include <linux/poll.h>
Frederic Weisbecker74876a92012-10-12 18:00:23 +020046#include <linux/irq_work.h>
Tejun Heo196779b2013-04-30 15:27:12 -070047#include <linux/utsname.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
49#include <asm/uaccess.h>
50
Johannes Berg95100352011-11-24 20:03:08 +010051#define CREATE_TRACE_POINTS
52#include <trace/events/printk.h>
53
Joe Perchesd197c432013-07-31 13:53:44 -070054#include "console_cmdline.h"
Joe Perchesbbeddf52013-07-31 13:53:45 -070055#include "braille.h"
Joe Perchesd197c432013-07-31 13:53:44 -070056
Linus Torvalds1da177e2005-04-16 15:20:36 -070057int console_printk[4] = {
Borislav Petkova8fe19e2014-06-04 16:11:46 -070058 CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */
Alex Elder42a9dc02014-08-06 16:09:01 -070059 MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */
Borislav Petkova8fe19e2014-06-04 16:11:46 -070060 CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */
61 CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */
Linus Torvalds1da177e2005-04-16 15:20:36 -070062};
63
Steven Rostedt458df9f2014-06-04 16:11:38 -070064/* Deferred messaged from sched code are marked by this special level */
65#define SCHED_MESSAGE_LOGLEVEL -2
66
Linus Torvalds1da177e2005-04-16 15:20:36 -070067/*
Patrick Pletscher0bbfb7c2007-02-17 20:10:16 +010068 * Low level drivers may need that to know if they can schedule in
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 * their unblank() callback or not. So let's export it.
70 */
71int oops_in_progress;
72EXPORT_SYMBOL(oops_in_progress);
73
74/*
75 * console_sem protects the console_drivers list, and also
76 * provides serialisation for access to the entire console
77 * driver system.
78 */
Thomas Gleixner5b8c4f22010-09-07 14:33:43 +000079static DEFINE_SEMAPHORE(console_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -070080struct console *console_drivers;
Ingo Molnara29d1cf2008-06-02 13:19:08 +020081EXPORT_SYMBOL_GPL(console_drivers);
82
Daniel Vetterdaee7792012-09-22 19:52:11 +020083#ifdef CONFIG_LOCKDEP
84static struct lockdep_map console_lock_dep_map = {
85 .name = "console_lock"
86};
87#endif
88
Linus Torvalds1da177e2005-04-16 15:20:36 -070089/*
Jan Karabd8d7cf2014-06-04 16:11:36 -070090 * Helper macros to handle lockdep when locking/unlocking console_sem. We use
91 * macros instead of functions so that _RET_IP_ contains useful information.
92 */
93#define down_console_sem() do { \
94 down(&console_sem);\
95 mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\
96} while (0)
97
98static int __down_trylock_console_sem(unsigned long ip)
99{
100 if (down_trylock(&console_sem))
101 return 1;
102 mutex_acquire(&console_lock_dep_map, 0, 1, ip);
103 return 0;
104}
105#define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_)
106
107#define up_console_sem() do { \
108 mutex_release(&console_lock_dep_map, 1, _RET_IP_);\
109 up(&console_sem);\
110} while (0)
111
112/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 * This is used for debugging the mess that is the VT code by
114 * keeping track if we have the console semaphore held. It's
115 * definitely not the perfect debug tool (we don't know if _WE_
Alex Elder0b90fec2014-08-06 16:09:03 -0700116 * hold it and are racing, but it helps tracking those weird code
117 * paths in the console code where we end up in places I want
118 * locked without the console sempahore held).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 */
Linus Torvalds557240b2006-06-19 18:16:01 -0700120static int console_locked, console_suspended;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121
122/*
Feng Tangfe3d8ad2011-03-22 16:34:21 -0700123 * If exclusive_console is non-NULL then only this console is to be printed to.
124 */
125static struct console *exclusive_console;
126
127/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 * Array of consoles built from command line options (console=)
129 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130
131#define MAX_CMDLINECONSOLES 8
132
133static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
Joe Perchesd197c432013-07-31 13:53:44 -0700134
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135static int selected_console = -1;
136static int preferred_console = -1;
Markus Armbruster9e124fe2008-05-26 23:31:07 +0100137int console_set_on_cmdline;
138EXPORT_SYMBOL(console_set_on_cmdline);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139
140/* Flag: console code may call schedule() */
141static int console_may_schedule;
142
Kay Sievers7ff95542012-05-03 02:29:13 +0200143/*
144 * The printk log buffer consists of a chain of concatenated variable
145 * length records. Every record starts with a record header, containing
146 * the overall length of the record.
147 *
148 * The heads to the first and last entry in the buffer, as well as the
Alex Elder0b90fec2014-08-06 16:09:03 -0700149 * sequence numbers of these entries are maintained when messages are
150 * stored.
Kay Sievers7ff95542012-05-03 02:29:13 +0200151 *
152 * If the heads indicate available messages, the length in the header
153 * tells the start next message. A length == 0 for the next message
154 * indicates a wrap-around to the beginning of the buffer.
155 *
156 * Every record carries the monotonic timestamp in microseconds, as well as
157 * the standard userspace syslog level and syslog facility. The usual
158 * kernel messages use LOG_KERN; userspace-injected messages always carry
159 * a matching syslog facility, by default LOG_USER. The origin of every
160 * message can be reliably determined that way.
161 *
162 * The human readable log message directly follows the message header. The
163 * length of the message text is stored in the header, the stored message
164 * is not terminated.
165 *
Kay Sieverse11fea92012-05-03 02:29:41 +0200166 * Optionally, a message can carry a dictionary of properties (key/value pairs),
167 * to provide userspace with a machine-readable message context.
168 *
169 * Examples for well-defined, commonly used property names are:
170 * DEVICE=b12:8 device identifier
171 * b12:8 block dev_t
172 * c127:3 char dev_t
173 * n8 netdev ifindex
174 * +sound:card0 subsystem:devname
175 * SUBSYSTEM=pci driver-core subsystem name
176 *
177 * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
178 * follows directly after a '=' character. Every property is terminated by
179 * a '\0' character. The last property is not terminated.
180 *
181 * Example of a message structure:
182 * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec
183 * 0008 34 00 record is 52 bytes long
184 * 000a 0b 00 text is 11 bytes long
185 * 000c 1f 00 dictionary is 23 bytes long
186 * 000e 03 00 LOG_KERN (facility) LOG_ERR (level)
187 * 0010 69 74 27 73 20 61 20 6c "it's a l"
188 * 69 6e 65 "ine"
189 * 001b 44 45 56 49 43 "DEVIC"
190 * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D"
191 * 52 49 56 45 52 3d 62 75 "RIVER=bu"
192 * 67 "g"
193 * 0032 00 00 00 padding to next message header
194 *
Joe Perches62e32ac2013-07-31 13:53:47 -0700195 * The 'struct printk_log' buffer header must never be directly exported to
Kay Sieverse11fea92012-05-03 02:29:41 +0200196 * userspace, it is a kernel-private implementation detail that might
197 * need to be changed in the future, when the requirements change.
198 *
199 * /dev/kmsg exports the structured data in the following line format:
200 * "level,sequnum,timestamp;<message text>\n"
201 *
202 * The optional key/value pairs are attached as continuation lines starting
203 * with a space character and terminated by a newline. All possible
204 * non-prinatable characters are escaped in the "\xff" notation.
205 *
206 * Users of the export format should ignore possible additional values
207 * separated by ',', and find the message after the ';' character.
Kay Sievers7ff95542012-05-03 02:29:13 +0200208 */
Matt Mackalld59745c2005-05-01 08:59:02 -0700209
Kay Sievers084681d2012-06-28 09:38:53 +0200210enum log_flags {
Kay Sievers5becfb12012-07-09 12:15:42 -0700211 LOG_NOCONS = 1, /* already flushed, do not print to console */
212 LOG_NEWLINE = 2, /* text ended with a newline */
213 LOG_PREFIX = 4, /* text started with a prefix */
214 LOG_CONT = 8, /* text is a fragment of a continuation line */
Kay Sievers084681d2012-06-28 09:38:53 +0200215};
216
Joe Perches62e32ac2013-07-31 13:53:47 -0700217struct printk_log {
Kay Sievers7ff95542012-05-03 02:29:13 +0200218 u64 ts_nsec; /* timestamp in nanoseconds */
219 u16 len; /* length of entire record */
220 u16 text_len; /* length of text buffer */
221 u16 dict_len; /* length of dictionary buffer */
Kay Sievers084681d2012-06-28 09:38:53 +0200222 u8 facility; /* syslog facility */
223 u8 flags:5; /* internal record flags */
224 u8 level:3; /* syslog level */
Kay Sievers7ff95542012-05-03 02:29:13 +0200225};
226
227/*
Steven Rostedt458df9f2014-06-04 16:11:38 -0700228 * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken
229 * within the scheduler's rq lock. It must be released before calling
230 * console_unlock() or anything else that might wake up a process.
Kay Sievers7ff95542012-05-03 02:29:13 +0200231 */
232static DEFINE_RAW_SPINLOCK(logbuf_lock);
233
Kay Sievers96efedf2012-07-16 18:35:29 -0700234#ifdef CONFIG_PRINTK
Frederic Weisbeckerdc72c322013-03-22 15:04:39 -0700235DECLARE_WAIT_QUEUE_HEAD(log_wait);
Kay Sievers7f3a7812012-05-09 01:37:51 +0200236/* the next printk record to read by syslog(READ) or /proc/kmsg */
237static u64 syslog_seq;
238static u32 syslog_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -0700239static enum log_flags syslog_prev;
Kay Sieverseb02dac2012-07-09 10:05:10 -0700240static size_t syslog_partial;
Kay Sievers7f3a7812012-05-09 01:37:51 +0200241
242/* index and sequence number of the first record stored in the buffer */
243static u64 log_first_seq;
244static u32 log_first_idx;
245
246/* index and sequence number of the next record to store in the buffer */
247static u64 log_next_seq;
Kay Sievers7f3a7812012-05-09 01:37:51 +0200248static u32 log_next_idx;
249
Kay Sieverseab07262012-07-16 18:35:30 -0700250/* the next printk record to write to the console */
251static u64 console_seq;
252static u32 console_idx;
253static enum log_flags console_prev;
254
Kay Sievers7f3a7812012-05-09 01:37:51 +0200255/* the next printk record to read after the last 'clear' command */
256static u64 clear_seq;
257static u32 clear_idx;
Kay Sievers7ff95542012-05-03 02:29:13 +0200258
Kay Sievers70498252012-07-16 18:35:29 -0700259#define PREFIX_MAX 32
260#define LOG_LINE_MAX 1024 - PREFIX_MAX
Kay Sievers7ff95542012-05-03 02:29:13 +0200261
262/* record buffer */
Andrew Lunn6ebb0172012-06-05 08:52:34 +0200263#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
Stephen Warrenf8450fc2012-05-10 16:14:33 -0600264#define LOG_ALIGN 4
265#else
Joe Perches62e32ac2013-07-31 13:53:47 -0700266#define LOG_ALIGN __alignof__(struct printk_log)
Stephen Warrenf8450fc2012-05-10 16:14:33 -0600267#endif
Kay Sievers7ff95542012-05-03 02:29:13 +0200268#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700269#define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT)
Stephen Warrenf8450fc2012-05-10 16:14:33 -0600270static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
Matt Mackalld59745c2005-05-01 08:59:02 -0700271static char *log_buf = __log_buf;
Kay Sievers7ff95542012-05-03 02:29:13 +0200272static u32 log_buf_len = __LOG_BUF_LEN;
273
Kay Sievers7ff95542012-05-03 02:29:13 +0200274/* human readable text of the record */
Joe Perches62e32ac2013-07-31 13:53:47 -0700275static char *log_text(const struct printk_log *msg)
Kay Sievers7ff95542012-05-03 02:29:13 +0200276{
Joe Perches62e32ac2013-07-31 13:53:47 -0700277 return (char *)msg + sizeof(struct printk_log);
Kay Sievers7ff95542012-05-03 02:29:13 +0200278}
279
280/* optional key/value pair dictionary attached to the record */
Joe Perches62e32ac2013-07-31 13:53:47 -0700281static char *log_dict(const struct printk_log *msg)
Kay Sievers7ff95542012-05-03 02:29:13 +0200282{
Joe Perches62e32ac2013-07-31 13:53:47 -0700283 return (char *)msg + sizeof(struct printk_log) + msg->text_len;
Kay Sievers7ff95542012-05-03 02:29:13 +0200284}
285
286/* get record by index; idx must point to valid msg */
Joe Perches62e32ac2013-07-31 13:53:47 -0700287static struct printk_log *log_from_idx(u32 idx)
Kay Sievers7ff95542012-05-03 02:29:13 +0200288{
Joe Perches62e32ac2013-07-31 13:53:47 -0700289 struct printk_log *msg = (struct printk_log *)(log_buf + idx);
Kay Sievers7ff95542012-05-03 02:29:13 +0200290
291 /*
292 * A length == 0 record is the end of buffer marker. Wrap around and
293 * read the message at the start of the buffer.
294 */
295 if (!msg->len)
Joe Perches62e32ac2013-07-31 13:53:47 -0700296 return (struct printk_log *)log_buf;
Kay Sievers7ff95542012-05-03 02:29:13 +0200297 return msg;
298}
299
300/* get next record; idx must point to valid msg */
301static u32 log_next(u32 idx)
302{
Joe Perches62e32ac2013-07-31 13:53:47 -0700303 struct printk_log *msg = (struct printk_log *)(log_buf + idx);
Kay Sievers7ff95542012-05-03 02:29:13 +0200304
305 /* length == 0 indicates the end of the buffer; wrap */
306 /*
307 * A length == 0 record is the end of buffer marker. Wrap around and
308 * read the message at the start of the buffer as *this* one, and
309 * return the one after that.
310 */
311 if (!msg->len) {
Joe Perches62e32ac2013-07-31 13:53:47 -0700312 msg = (struct printk_log *)log_buf;
Kay Sievers7ff95542012-05-03 02:29:13 +0200313 return msg->len;
314 }
315 return idx + msg->len;
316}
317
Petr Mladekf40e4b92014-06-04 16:11:30 -0700318/*
319 * Check whether there is enough free space for the given message.
320 *
321 * The same values of first_idx and next_idx mean that the buffer
322 * is either empty or full.
323 *
324 * If the buffer is empty, we must respect the position of the indexes.
325 * They cannot be reset to the beginning of the buffer.
326 */
327static int logbuf_has_space(u32 msg_size, bool empty)
Petr Mladek0a581692014-06-04 16:11:28 -0700328{
329 u32 free;
330
Petr Mladekf40e4b92014-06-04 16:11:30 -0700331 if (log_next_idx > log_first_idx || empty)
Petr Mladek0a581692014-06-04 16:11:28 -0700332 free = max(log_buf_len - log_next_idx, log_first_idx);
333 else
334 free = log_first_idx - log_next_idx;
335
336 /*
337 * We need space also for an empty header that signalizes wrapping
338 * of the buffer.
339 */
340 return free >= msg_size + sizeof(struct printk_log);
341}
342
Petr Mladekf40e4b92014-06-04 16:11:30 -0700343static int log_make_free_space(u32 msg_size)
Petr Mladek0a581692014-06-04 16:11:28 -0700344{
345 while (log_first_seq < log_next_seq) {
Petr Mladekf40e4b92014-06-04 16:11:30 -0700346 if (logbuf_has_space(msg_size, false))
347 return 0;
Alex Elder0b90fec2014-08-06 16:09:03 -0700348 /* drop old messages until we have enough contiguous space */
Petr Mladek0a581692014-06-04 16:11:28 -0700349 log_first_idx = log_next(log_first_idx);
350 log_first_seq++;
351 }
Petr Mladekf40e4b92014-06-04 16:11:30 -0700352
353 /* sequence numbers are equal, so the log buffer is empty */
354 if (logbuf_has_space(msg_size, true))
355 return 0;
356
357 return -ENOMEM;
Petr Mladek0a581692014-06-04 16:11:28 -0700358}
359
Petr Mladek85c870432014-06-04 16:11:31 -0700360/* compute the message size including the padding bytes */
361static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len)
362{
363 u32 size;
364
365 size = sizeof(struct printk_log) + text_len + dict_len;
366 *pad_len = (-size) & (LOG_ALIGN - 1);
367 size += *pad_len;
368
369 return size;
370}
371
Petr Mladek55bd53a2014-06-04 16:11:32 -0700372/*
373 * Define how much of the log buffer we could take at maximum. The value
374 * must be greater than two. Note that only half of the buffer is available
375 * when the index points to the middle.
376 */
377#define MAX_LOG_TAKE_PART 4
378static const char trunc_msg[] = "<truncated>";
379
380static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len,
381 u16 *dict_len, u32 *pad_len)
382{
383 /*
384 * The message should not take the whole buffer. Otherwise, it might
385 * get removed too soon.
386 */
387 u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART;
388 if (*text_len > max_text_len)
389 *text_len = max_text_len;
390 /* enable the warning message */
391 *trunc_msg_len = strlen(trunc_msg);
392 /* disable the "dict" completely */
393 *dict_len = 0;
394 /* compute the size again, count also the warning message */
395 return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len);
396}
397
Kay Sievers7ff95542012-05-03 02:29:13 +0200398/* insert record into the buffer, discard old ones, update heads */
Petr Mladek034633c2014-06-04 16:11:33 -0700399static int log_store(int facility, int level,
400 enum log_flags flags, u64 ts_nsec,
401 const char *dict, u16 dict_len,
402 const char *text, u16 text_len)
Kay Sievers7ff95542012-05-03 02:29:13 +0200403{
Joe Perches62e32ac2013-07-31 13:53:47 -0700404 struct printk_log *msg;
Kay Sievers7ff95542012-05-03 02:29:13 +0200405 u32 size, pad_len;
Petr Mladek55bd53a2014-06-04 16:11:32 -0700406 u16 trunc_msg_len = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +0200407
408 /* number of '\0' padding bytes to next message */
Petr Mladek85c870432014-06-04 16:11:31 -0700409 size = msg_used_size(text_len, dict_len, &pad_len);
Kay Sievers7ff95542012-05-03 02:29:13 +0200410
Petr Mladek55bd53a2014-06-04 16:11:32 -0700411 if (log_make_free_space(size)) {
412 /* truncate the message if it is too long for empty buffer */
413 size = truncate_msg(&text_len, &trunc_msg_len,
414 &dict_len, &pad_len);
415 /* survive when the log buffer is too small for trunc_msg */
416 if (log_make_free_space(size))
Petr Mladek034633c2014-06-04 16:11:33 -0700417 return 0;
Petr Mladek55bd53a2014-06-04 16:11:32 -0700418 }
Kay Sievers7ff95542012-05-03 02:29:13 +0200419
Petr Mladek39b25102014-04-03 14:48:42 -0700420 if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) {
Kay Sievers7ff95542012-05-03 02:29:13 +0200421 /*
422 * This message + an additional empty header does not fit
423 * at the end of the buffer. Add an empty header with len == 0
424 * to signify a wrap around.
425 */
Joe Perches62e32ac2013-07-31 13:53:47 -0700426 memset(log_buf + log_next_idx, 0, sizeof(struct printk_log));
Kay Sievers7ff95542012-05-03 02:29:13 +0200427 log_next_idx = 0;
428 }
429
430 /* fill message */
Joe Perches62e32ac2013-07-31 13:53:47 -0700431 msg = (struct printk_log *)(log_buf + log_next_idx);
Kay Sievers7ff95542012-05-03 02:29:13 +0200432 memcpy(log_text(msg), text, text_len);
433 msg->text_len = text_len;
Petr Mladek55bd53a2014-06-04 16:11:32 -0700434 if (trunc_msg_len) {
435 memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len);
436 msg->text_len += trunc_msg_len;
437 }
Kay Sievers7ff95542012-05-03 02:29:13 +0200438 memcpy(log_dict(msg), dict, dict_len);
439 msg->dict_len = dict_len;
Kay Sievers084681d2012-06-28 09:38:53 +0200440 msg->facility = facility;
441 msg->level = level & 7;
442 msg->flags = flags & 0x1f;
443 if (ts_nsec > 0)
444 msg->ts_nsec = ts_nsec;
445 else
446 msg->ts_nsec = local_clock();
Kay Sievers7ff95542012-05-03 02:29:13 +0200447 memset(log_dict(msg) + dict_len, 0, pad_len);
Petr Mladekfce6e032014-04-03 14:48:43 -0700448 msg->len = size;
Kay Sievers7ff95542012-05-03 02:29:13 +0200449
450 /* insert message */
451 log_next_idx += msg->len;
452 log_next_seq++;
Petr Mladek034633c2014-06-04 16:11:33 -0700453
454 return msg->text_len;
Kay Sievers7ff95542012-05-03 02:29:13 +0200455}
Matt Mackalld59745c2005-05-01 08:59:02 -0700456
Alex Eldere99aa462014-08-06 16:09:05 -0700457int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT);
Kees Cook637241a2013-06-12 14:04:39 -0700458
459static int syslog_action_restricted(int type)
460{
461 if (dmesg_restrict)
462 return 1;
463 /*
464 * Unless restricted, we allow "read all" and "get buffer size"
465 * for everybody.
466 */
467 return type != SYSLOG_ACTION_READ_ALL &&
468 type != SYSLOG_ACTION_SIZE_BUFFER;
469}
470
471static int check_syslog_permissions(int type, bool from_file)
472{
473 /*
474 * If this is from /proc/kmsg and we've already opened it, then we've
475 * already done the capabilities checks at open time.
476 */
477 if (from_file && type != SYSLOG_ACTION_OPEN)
478 return 0;
479
480 if (syslog_action_restricted(type)) {
481 if (capable(CAP_SYSLOG))
482 return 0;
483 /*
484 * For historical reasons, accept CAP_SYS_ADMIN too, with
485 * a warning.
486 */
487 if (capable(CAP_SYS_ADMIN)) {
488 pr_warn_once("%s (%d): Attempt to access syslog with "
489 "CAP_SYS_ADMIN but no CAP_SYSLOG "
490 "(deprecated).\n",
491 current->comm, task_pid_nr(current));
492 return 0;
493 }
494 return -EPERM;
495 }
496 return security_syslog(type);
497}
498
499
Kay Sieverse11fea92012-05-03 02:29:41 +0200500/* /dev/kmsg - userspace message inject/listen interface */
501struct devkmsg_user {
502 u64 seq;
503 u32 idx;
Kay Sieversd39f3d72012-07-16 18:35:30 -0700504 enum log_flags prev;
Kay Sieverse11fea92012-05-03 02:29:41 +0200505 struct mutex lock;
506 char buf[8192];
507};
508
509static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
510 unsigned long count, loff_t pos)
511{
512 char *buf, *line;
513 int i;
514 int level = default_message_loglevel;
515 int facility = 1; /* LOG_USER */
516 size_t len = iov_length(iv, count);
517 ssize_t ret = len;
518
519 if (len > LOG_LINE_MAX)
520 return -EINVAL;
521 buf = kmalloc(len+1, GFP_KERNEL);
522 if (buf == NULL)
523 return -ENOMEM;
524
525 line = buf;
526 for (i = 0; i < count; i++) {
Kay Sieverscdf53442012-07-30 14:40:08 -0700527 if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) {
528 ret = -EFAULT;
Kay Sieverse11fea92012-05-03 02:29:41 +0200529 goto out;
Kay Sieverscdf53442012-07-30 14:40:08 -0700530 }
Kay Sieverse11fea92012-05-03 02:29:41 +0200531 line += iv[i].iov_len;
532 }
533
534 /*
535 * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace
536 * the decimal value represents 32bit, the lower 3 bit are the log
537 * level, the rest are the log facility.
538 *
539 * If no prefix or no userspace facility is specified, we
540 * enforce LOG_USER, to be able to reliably distinguish
541 * kernel-generated messages from userspace-injected ones.
542 */
543 line = buf;
544 if (line[0] == '<') {
545 char *endp = NULL;
546
547 i = simple_strtoul(line+1, &endp, 10);
548 if (endp && endp[0] == '>') {
549 level = i & 7;
550 if (i >> 3)
551 facility = i >> 3;
552 endp++;
553 len -= endp - line;
554 line = endp;
555 }
556 }
557 line[len] = '\0';
558
559 printk_emit(facility, level, NULL, 0, "%s", line);
560out:
561 kfree(buf);
562 return ret;
563}
564
565static ssize_t devkmsg_read(struct file *file, char __user *buf,
566 size_t count, loff_t *ppos)
567{
568 struct devkmsg_user *user = file->private_data;
Joe Perches62e32ac2013-07-31 13:53:47 -0700569 struct printk_log *msg;
Kay Sievers5fc324902012-05-08 13:04:17 +0200570 u64 ts_usec;
Kay Sieverse11fea92012-05-03 02:29:41 +0200571 size_t i;
Kay Sieversd39f3d72012-07-16 18:35:30 -0700572 char cont = '-';
Kay Sieverse11fea92012-05-03 02:29:41 +0200573 size_t len;
574 ssize_t ret;
575
576 if (!user)
577 return -EBADF;
578
Yuanhan Liu4a77a5a2012-06-16 21:21:51 +0800579 ret = mutex_lock_interruptible(&user->lock);
580 if (ret)
581 return ret;
liu chuansheng5c53d812012-07-06 09:50:08 -0700582 raw_spin_lock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200583 while (user->seq == log_next_seq) {
584 if (file->f_flags & O_NONBLOCK) {
585 ret = -EAGAIN;
liu chuansheng5c53d812012-07-06 09:50:08 -0700586 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200587 goto out;
588 }
589
liu chuansheng5c53d812012-07-06 09:50:08 -0700590 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200591 ret = wait_event_interruptible(log_wait,
592 user->seq != log_next_seq);
593 if (ret)
594 goto out;
liu chuansheng5c53d812012-07-06 09:50:08 -0700595 raw_spin_lock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200596 }
597
598 if (user->seq < log_first_seq) {
599 /* our last seen message is gone, return error and reset */
600 user->idx = log_first_idx;
601 user->seq = log_first_seq;
602 ret = -EPIPE;
liu chuansheng5c53d812012-07-06 09:50:08 -0700603 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200604 goto out;
605 }
606
607 msg = log_from_idx(user->idx);
Kay Sievers5fc324902012-05-08 13:04:17 +0200608 ts_usec = msg->ts_nsec;
609 do_div(ts_usec, 1000);
Kay Sieversd39f3d72012-07-16 18:35:30 -0700610
611 /*
612 * If we couldn't merge continuation line fragments during the print,
613 * export the stored flags to allow an optional external merge of the
614 * records. Merging the records isn't always neccessarily correct, like
615 * when we hit a race during printing. In most cases though, it produces
616 * better readable output. 'c' in the record flags mark the first
617 * fragment of a line, '+' the following.
618 */
619 if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT))
620 cont = 'c';
621 else if ((msg->flags & LOG_CONT) ||
622 ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
623 cont = '+';
624
625 len = sprintf(user->buf, "%u,%llu,%llu,%c;",
626 (msg->facility << 3) | msg->level,
627 user->seq, ts_usec, cont);
628 user->prev = msg->flags;
Kay Sieverse11fea92012-05-03 02:29:41 +0200629
630 /* escape non-printable characters */
631 for (i = 0; i < msg->text_len; i++) {
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200632 unsigned char c = log_text(msg)[i];
Kay Sieverse11fea92012-05-03 02:29:41 +0200633
Kay Sieverse3f5a5f2012-07-06 09:50:09 -0700634 if (c < ' ' || c >= 127 || c == '\\')
Kay Sieverse11fea92012-05-03 02:29:41 +0200635 len += sprintf(user->buf + len, "\\x%02x", c);
636 else
637 user->buf[len++] = c;
638 }
639 user->buf[len++] = '\n';
640
641 if (msg->dict_len) {
642 bool line = true;
643
644 for (i = 0; i < msg->dict_len; i++) {
Kay Sievers3ce9a7c2012-05-13 23:30:46 +0200645 unsigned char c = log_dict(msg)[i];
Kay Sieverse11fea92012-05-03 02:29:41 +0200646
647 if (line) {
648 user->buf[len++] = ' ';
649 line = false;
650 }
651
652 if (c == '\0') {
653 user->buf[len++] = '\n';
654 line = true;
655 continue;
656 }
657
Kay Sieverse3f5a5f2012-07-06 09:50:09 -0700658 if (c < ' ' || c >= 127 || c == '\\') {
Kay Sieverse11fea92012-05-03 02:29:41 +0200659 len += sprintf(user->buf + len, "\\x%02x", c);
660 continue;
661 }
662
663 user->buf[len++] = c;
664 }
665 user->buf[len++] = '\n';
666 }
667
668 user->idx = log_next(user->idx);
669 user->seq++;
liu chuansheng5c53d812012-07-06 09:50:08 -0700670 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200671
672 if (len > count) {
673 ret = -EINVAL;
674 goto out;
675 }
676
677 if (copy_to_user(buf, user->buf, len)) {
678 ret = -EFAULT;
679 goto out;
680 }
681 ret = len;
682out:
683 mutex_unlock(&user->lock);
684 return ret;
685}
686
687static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
688{
689 struct devkmsg_user *user = file->private_data;
690 loff_t ret = 0;
691
692 if (!user)
693 return -EBADF;
694 if (offset)
695 return -ESPIPE;
696
liu chuansheng5c53d812012-07-06 09:50:08 -0700697 raw_spin_lock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200698 switch (whence) {
699 case SEEK_SET:
700 /* the first record */
701 user->idx = log_first_idx;
702 user->seq = log_first_seq;
703 break;
704 case SEEK_DATA:
705 /*
706 * The first record after the last SYSLOG_ACTION_CLEAR,
707 * like issued by 'dmesg -c'. Reading /dev/kmsg itself
708 * changes no global state, and does not clear anything.
709 */
710 user->idx = clear_idx;
711 user->seq = clear_seq;
712 break;
713 case SEEK_END:
714 /* after the last record */
715 user->idx = log_next_idx;
716 user->seq = log_next_seq;
717 break;
718 default:
719 ret = -EINVAL;
720 }
liu chuansheng5c53d812012-07-06 09:50:08 -0700721 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200722 return ret;
723}
724
725static unsigned int devkmsg_poll(struct file *file, poll_table *wait)
726{
727 struct devkmsg_user *user = file->private_data;
728 int ret = 0;
729
730 if (!user)
731 return POLLERR|POLLNVAL;
732
733 poll_wait(file, &log_wait, wait);
734
liu chuansheng5c53d812012-07-06 09:50:08 -0700735 raw_spin_lock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200736 if (user->seq < log_next_seq) {
737 /* return error when data has vanished underneath us */
738 if (user->seq < log_first_seq)
739 ret = POLLIN|POLLRDNORM|POLLERR|POLLPRI;
Nicolas Kaiser0a285312013-04-29 16:17:20 -0700740 else
741 ret = POLLIN|POLLRDNORM;
Kay Sieverse11fea92012-05-03 02:29:41 +0200742 }
liu chuansheng5c53d812012-07-06 09:50:08 -0700743 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200744
745 return ret;
746}
747
748static int devkmsg_open(struct inode *inode, struct file *file)
749{
750 struct devkmsg_user *user;
751 int err;
752
753 /* write-only does not need any file context */
754 if ((file->f_flags & O_ACCMODE) == O_WRONLY)
755 return 0;
756
Kees Cook637241a2013-06-12 14:04:39 -0700757 err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
758 SYSLOG_FROM_READER);
Kay Sieverse11fea92012-05-03 02:29:41 +0200759 if (err)
760 return err;
761
762 user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL);
763 if (!user)
764 return -ENOMEM;
765
766 mutex_init(&user->lock);
767
liu chuansheng5c53d812012-07-06 09:50:08 -0700768 raw_spin_lock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200769 user->idx = log_first_idx;
770 user->seq = log_first_seq;
liu chuansheng5c53d812012-07-06 09:50:08 -0700771 raw_spin_unlock_irq(&logbuf_lock);
Kay Sieverse11fea92012-05-03 02:29:41 +0200772
773 file->private_data = user;
774 return 0;
775}
776
777static int devkmsg_release(struct inode *inode, struct file *file)
778{
779 struct devkmsg_user *user = file->private_data;
780
781 if (!user)
782 return 0;
783
784 mutex_destroy(&user->lock);
785 kfree(user);
786 return 0;
787}
788
789const struct file_operations kmsg_fops = {
790 .open = devkmsg_open,
791 .read = devkmsg_read,
792 .aio_write = devkmsg_writev,
793 .llseek = devkmsg_llseek,
794 .poll = devkmsg_poll,
795 .release = devkmsg_release,
796};
797
Neil Horman04d491a2009-04-02 16:58:57 -0700798#ifdef CONFIG_KEXEC
799/*
Dirk Gouders4c1ace62013-11-12 15:08:54 -0800800 * This appends the listed symbols to /proc/vmcore
Neil Horman04d491a2009-04-02 16:58:57 -0700801 *
Dirk Gouders4c1ace62013-11-12 15:08:54 -0800802 * /proc/vmcore is used by various utilities, like crash and makedumpfile to
Neil Horman04d491a2009-04-02 16:58:57 -0700803 * obtain access to symbols that are otherwise very difficult to locate. These
804 * symbols are specifically used so that utilities can access and extract the
805 * dmesg log from a vmcore file after a crash.
806 */
807void log_buf_kexec_setup(void)
808{
809 VMCOREINFO_SYMBOL(log_buf);
Neil Horman04d491a2009-04-02 16:58:57 -0700810 VMCOREINFO_SYMBOL(log_buf_len);
Kay Sievers7ff95542012-05-03 02:29:13 +0200811 VMCOREINFO_SYMBOL(log_first_idx);
812 VMCOREINFO_SYMBOL(log_next_idx);
Vivek Goyal67914572012-07-18 13:18:12 -0400813 /*
Joe Perches62e32ac2013-07-31 13:53:47 -0700814 * Export struct printk_log size and field offsets. User space tools can
Vivek Goyal67914572012-07-18 13:18:12 -0400815 * parse it and detect any changes to structure down the line.
816 */
Joe Perches62e32ac2013-07-31 13:53:47 -0700817 VMCOREINFO_STRUCT_SIZE(printk_log);
818 VMCOREINFO_OFFSET(printk_log, ts_nsec);
819 VMCOREINFO_OFFSET(printk_log, len);
820 VMCOREINFO_OFFSET(printk_log, text_len);
821 VMCOREINFO_OFFSET(printk_log, dict_len);
Neil Horman04d491a2009-04-02 16:58:57 -0700822}
823#endif
824
Mike Travis162a7e72011-05-24 17:13:20 -0700825/* requested log_buf_len from kernel cmdline */
826static unsigned long __initdata new_log_buf_len;
827
Luis R. Rodriguezc0a318a2014-08-06 16:08:52 -0700828/* we practice scaling the ring buffer by powers of 2 */
829static void __init log_buf_len_update(unsigned size)
830{
831 if (size)
832 size = roundup_pow_of_two(size);
833 if (size > log_buf_len)
834 new_log_buf_len = size;
835}
836
Mike Travis162a7e72011-05-24 17:13:20 -0700837/* save requested log_buf_len since it's too early to process it */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838static int __init log_buf_len_setup(char *str)
839{
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800840 unsigned size = memparse(str, &str);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841
Luis R. Rodriguezc0a318a2014-08-06 16:08:52 -0700842 log_buf_len_update(size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843
Mike Travis162a7e72011-05-24 17:13:20 -0700844 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845}
Mike Travis162a7e72011-05-24 17:13:20 -0700846early_param("log_buf_len", log_buf_len_setup);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700848static void __init log_buf_add_cpu(void)
849{
850 unsigned int cpu_extra;
851
852 /*
853 * archs should set up cpu_possible_bits properly with
854 * set_cpu_possible() after setup_arch() but just in
855 * case lets ensure this is valid.
856 */
857 if (num_possible_cpus() == 1)
858 return;
859
860 cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN;
861
862 /* by default this will only continue through for large > 64 CPUs */
863 if (cpu_extra <= __LOG_BUF_LEN / 2)
864 return;
865
866 pr_info("log_buf_len individual max cpu contribution: %d bytes\n",
867 __LOG_CPU_MAX_BUF_LEN);
868 pr_info("log_buf_len total cpu_extra contributions: %d bytes\n",
869 cpu_extra);
870 pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN);
871
872 log_buf_len_update(cpu_extra + __LOG_BUF_LEN);
873}
874
Mike Travis162a7e72011-05-24 17:13:20 -0700875void __init setup_log_buf(int early)
876{
877 unsigned long flags;
Mike Travis162a7e72011-05-24 17:13:20 -0700878 char *new_log_buf;
879 int free;
880
Luis R. Rodriguez23b28992014-08-06 16:08:56 -0700881 if (log_buf != __log_buf)
882 return;
883
884 if (!early && !new_log_buf_len)
885 log_buf_add_cpu();
886
Mike Travis162a7e72011-05-24 17:13:20 -0700887 if (!new_log_buf_len)
888 return;
889
890 if (early) {
Santosh Shilimkar9da791d2014-01-21 15:50:23 -0800891 new_log_buf =
Luis R. Rodriguez70300172014-08-06 16:08:49 -0700892 memblock_virt_alloc(new_log_buf_len, LOG_ALIGN);
Mike Travis162a7e72011-05-24 17:13:20 -0700893 } else {
Luis R. Rodriguez70300172014-08-06 16:08:49 -0700894 new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len,
895 LOG_ALIGN);
Mike Travis162a7e72011-05-24 17:13:20 -0700896 }
897
898 if (unlikely(!new_log_buf)) {
899 pr_err("log_buf_len: %ld bytes not available\n",
900 new_log_buf_len);
901 return;
902 }
903
Thomas Gleixner07354eb2009-07-25 17:50:36 +0200904 raw_spin_lock_irqsave(&logbuf_lock, flags);
Mike Travis162a7e72011-05-24 17:13:20 -0700905 log_buf_len = new_log_buf_len;
906 log_buf = new_log_buf;
907 new_log_buf_len = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +0200908 free = __LOG_BUF_LEN - log_next_idx;
909 memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
Thomas Gleixner07354eb2009-07-25 17:50:36 +0200910 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
Mike Travis162a7e72011-05-24 17:13:20 -0700911
Luis R. Rodriguezf5405172014-08-06 16:08:54 -0700912 pr_info("log_buf_len: %d bytes\n", log_buf_len);
Mike Travis162a7e72011-05-24 17:13:20 -0700913 pr_info("early log buf free: %d(%d%%)\n",
914 free, (free * 100) / __LOG_BUF_LEN);
915}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916
Andrew Cooks2fa72c82012-12-17 15:59:56 -0800917static bool __read_mostly ignore_loglevel;
918
919static int __init ignore_loglevel_setup(char *str)
920{
921 ignore_loglevel = 1;
Andrew Morton27083ba2013-11-12 15:08:50 -0800922 pr_info("debug: ignoring loglevel setting.\n");
Andrew Cooks2fa72c82012-12-17 15:59:56 -0800923
924 return 0;
925}
926
927early_param("ignore_loglevel", ignore_loglevel_setup);
928module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR);
929MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to"
930 "print all kernel messages to the console.");
931
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700932#ifdef CONFIG_BOOT_PRINTK_DELAY
933
Namhyung Kim674dff62010-10-26 14:22:48 -0700934static int boot_delay; /* msecs delay after each printk during bootup */
Dave Young3a3b6ed2009-09-22 16:43:31 -0700935static unsigned long long loops_per_msec; /* based on boot_delay */
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700936
937static int __init boot_delay_setup(char *str)
938{
939 unsigned long lpj;
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700940
941 lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */
942 loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
943
944 get_option(&str, &boot_delay);
945 if (boot_delay > 10 * 1000)
946 boot_delay = 0;
947
Dave Young3a3b6ed2009-09-22 16:43:31 -0700948 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
949 "HZ: %d, loops_per_msec: %llu\n",
950 boot_delay, preset_lpj, lpj, HZ, loops_per_msec);
Dave Young29e9d222013-11-12 15:08:53 -0800951 return 0;
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700952}
Dave Young29e9d222013-11-12 15:08:53 -0800953early_param("boot_delay", boot_delay_setup);
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700954
Andrew Cooks2fa72c82012-12-17 15:59:56 -0800955static void boot_delay_msec(int level)
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700956{
957 unsigned long long k;
958 unsigned long timeout;
959
Andrew Cooks2fa72c82012-12-17 15:59:56 -0800960 if ((boot_delay == 0 || system_state != SYSTEM_BOOTING)
961 || (level >= console_loglevel && !ignore_loglevel)) {
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700962 return;
Andrew Cooks2fa72c82012-12-17 15:59:56 -0800963 }
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700964
Dave Young3a3b6ed2009-09-22 16:43:31 -0700965 k = (unsigned long long)loops_per_msec * boot_delay;
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700966
967 timeout = jiffies + msecs_to_jiffies(boot_delay);
968 while (k) {
969 k--;
970 cpu_relax();
971 /*
972 * use (volatile) jiffies to prevent
973 * compiler reduction; loop termination via jiffies
974 * is secondary and may or may not happen.
975 */
976 if (time_after(jiffies, timeout))
977 break;
978 touch_nmi_watchdog();
979 }
980}
981#else
Andrew Cooks2fa72c82012-12-17 15:59:56 -0800982static inline void boot_delay_msec(int level)
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700983{
984}
985#endif
986
Alex Eldere99aa462014-08-06 16:09:05 -0700987static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME);
Kay Sievers7ff95542012-05-03 02:29:13 +0200988module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
989
Kay Sievers084681d2012-06-28 09:38:53 +0200990static size_t print_time(u64 ts, char *buf)
991{
992 unsigned long rem_nsec;
993
994 if (!printk_time)
995 return 0;
996
Kay Sievers084681d2012-06-28 09:38:53 +0200997 rem_nsec = do_div(ts, 1000000000);
Roland Dreier35dac272013-01-04 15:35:50 -0800998
999 if (!buf)
1000 return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts);
1001
Kay Sievers084681d2012-06-28 09:38:53 +02001002 return sprintf(buf, "[%5lu.%06lu] ",
1003 (unsigned long)ts, rem_nsec / 1000);
1004}
1005
Joe Perches62e32ac2013-07-31 13:53:47 -07001006static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf)
Kay Sievers649e6ee2012-05-10 04:30:45 +02001007{
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001008 size_t len = 0;
Kay Sievers43a73a52012-07-06 09:50:09 -07001009 unsigned int prefix = (msg->facility << 3) | msg->level;
Kay Sievers649e6ee2012-05-10 04:30:45 +02001010
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001011 if (syslog) {
1012 if (buf) {
Kay Sievers43a73a52012-07-06 09:50:09 -07001013 len += sprintf(buf, "<%u>", prefix);
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001014 } else {
1015 len += 3;
Kay Sievers43a73a52012-07-06 09:50:09 -07001016 if (prefix > 999)
1017 len += 3;
1018 else if (prefix > 99)
1019 len += 2;
1020 else if (prefix > 9)
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001021 len++;
1022 }
Kay Sievers7ff95542012-05-03 02:29:13 +02001023 }
1024
Kay Sievers084681d2012-06-28 09:38:53 +02001025 len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001026 return len;
1027}
1028
Joe Perches62e32ac2013-07-31 13:53:47 -07001029static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev,
Kay Sievers5becfb12012-07-09 12:15:42 -07001030 bool syslog, char *buf, size_t size)
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001031{
1032 const char *text = log_text(msg);
1033 size_t text_size = msg->text_len;
Kay Sievers5becfb12012-07-09 12:15:42 -07001034 bool prefix = true;
1035 bool newline = true;
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001036 size_t len = 0;
1037
Kay Sievers5becfb12012-07-09 12:15:42 -07001038 if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
1039 prefix = false;
1040
1041 if (msg->flags & LOG_CONT) {
1042 if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE))
1043 prefix = false;
1044
1045 if (!(msg->flags & LOG_NEWLINE))
1046 newline = false;
1047 }
1048
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001049 do {
1050 const char *next = memchr(text, '\n', text_size);
1051 size_t text_len;
1052
1053 if (next) {
1054 text_len = next - text;
1055 next++;
1056 text_size -= next - text;
1057 } else {
1058 text_len = text_size;
1059 }
1060
1061 if (buf) {
1062 if (print_prefix(msg, syslog, NULL) +
Kay Sievers70498252012-07-16 18:35:29 -07001063 text_len + 1 >= size - len)
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001064 break;
1065
Kay Sievers5becfb12012-07-09 12:15:42 -07001066 if (prefix)
1067 len += print_prefix(msg, syslog, buf + len);
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001068 memcpy(buf + len, text, text_len);
1069 len += text_len;
Kay Sievers5becfb12012-07-09 12:15:42 -07001070 if (next || newline)
1071 buf[len++] = '\n';
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001072 } else {
1073 /* SYSLOG_ACTION_* buffer size only calculation */
Kay Sievers5becfb12012-07-09 12:15:42 -07001074 if (prefix)
1075 len += print_prefix(msg, syslog, NULL);
1076 len += text_len;
1077 if (next || newline)
1078 len++;
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001079 }
1080
Kay Sievers5becfb12012-07-09 12:15:42 -07001081 prefix = true;
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001082 text = next;
1083 } while (text);
1084
Kay Sievers7ff95542012-05-03 02:29:13 +02001085 return len;
1086}
1087
1088static int syslog_print(char __user *buf, int size)
1089{
1090 char *text;
Joe Perches62e32ac2013-07-31 13:53:47 -07001091 struct printk_log *msg;
Jan Beulich116e90b2012-06-22 16:36:09 +01001092 int len = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001093
Kay Sievers70498252012-07-16 18:35:29 -07001094 text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
Kay Sievers7ff95542012-05-03 02:29:13 +02001095 if (!text)
1096 return -ENOMEM;
1097
Jan Beulich116e90b2012-06-22 16:36:09 +01001098 while (size > 0) {
1099 size_t n;
Kay Sieverseb02dac2012-07-09 10:05:10 -07001100 size_t skip;
Kay Sievers7ff95542012-05-03 02:29:13 +02001101
Jan Beulich116e90b2012-06-22 16:36:09 +01001102 raw_spin_lock_irq(&logbuf_lock);
1103 if (syslog_seq < log_first_seq) {
1104 /* messages are gone, move to first one */
1105 syslog_seq = log_first_seq;
1106 syslog_idx = log_first_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07001107 syslog_prev = 0;
Kay Sieverseb02dac2012-07-09 10:05:10 -07001108 syslog_partial = 0;
Jan Beulich116e90b2012-06-22 16:36:09 +01001109 }
1110 if (syslog_seq == log_next_seq) {
1111 raw_spin_unlock_irq(&logbuf_lock);
1112 break;
1113 }
Kay Sieverseb02dac2012-07-09 10:05:10 -07001114
1115 skip = syslog_partial;
Jan Beulich116e90b2012-06-22 16:36:09 +01001116 msg = log_from_idx(syslog_idx);
Kay Sievers70498252012-07-16 18:35:29 -07001117 n = msg_print_text(msg, syslog_prev, true, text,
1118 LOG_LINE_MAX + PREFIX_MAX);
Kay Sieverseb02dac2012-07-09 10:05:10 -07001119 if (n - syslog_partial <= size) {
1120 /* message fits into buffer, move forward */
Jan Beulich116e90b2012-06-22 16:36:09 +01001121 syslog_idx = log_next(syslog_idx);
1122 syslog_seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07001123 syslog_prev = msg->flags;
Kay Sieverseb02dac2012-07-09 10:05:10 -07001124 n -= syslog_partial;
1125 syslog_partial = 0;
1126 } else if (!len){
1127 /* partial read(), remember position */
1128 n = size;
1129 syslog_partial += n;
Jan Beulich116e90b2012-06-22 16:36:09 +01001130 } else
1131 n = 0;
1132 raw_spin_unlock_irq(&logbuf_lock);
1133
1134 if (!n)
1135 break;
1136
Kay Sieverseb02dac2012-07-09 10:05:10 -07001137 if (copy_to_user(buf, text + skip, n)) {
Jan Beulich116e90b2012-06-22 16:36:09 +01001138 if (!len)
1139 len = -EFAULT;
1140 break;
1141 }
Kay Sieverseb02dac2012-07-09 10:05:10 -07001142
1143 len += n;
1144 size -= n;
1145 buf += n;
Jan Beulich116e90b2012-06-22 16:36:09 +01001146 }
Kay Sievers7ff95542012-05-03 02:29:13 +02001147
1148 kfree(text);
1149 return len;
1150}
1151
1152static int syslog_print_all(char __user *buf, int size, bool clear)
1153{
1154 char *text;
1155 int len = 0;
1156
Kay Sievers70498252012-07-16 18:35:29 -07001157 text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
Kay Sievers7ff95542012-05-03 02:29:13 +02001158 if (!text)
1159 return -ENOMEM;
1160
1161 raw_spin_lock_irq(&logbuf_lock);
1162 if (buf) {
1163 u64 next_seq;
1164 u64 seq;
1165 u32 idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07001166 enum log_flags prev;
Kay Sievers7ff95542012-05-03 02:29:13 +02001167
1168 if (clear_seq < log_first_seq) {
1169 /* messages are gone, move to first available one */
1170 clear_seq = log_first_seq;
1171 clear_idx = log_first_idx;
1172 }
1173
1174 /*
1175 * Find first record that fits, including all following records,
1176 * into the user-provided buffer for this dump.
Kay Sieverse2ae7152012-06-15 14:07:51 +02001177 */
Kay Sievers7ff95542012-05-03 02:29:13 +02001178 seq = clear_seq;
1179 idx = clear_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07001180 prev = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001181 while (seq < log_next_seq) {
Joe Perches62e32ac2013-07-31 13:53:47 -07001182 struct printk_log *msg = log_from_idx(idx);
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001183
Kay Sievers5becfb12012-07-09 12:15:42 -07001184 len += msg_print_text(msg, prev, true, NULL, 0);
Jeff Mahoneye3756472012-08-10 15:07:09 -04001185 prev = msg->flags;
Kay Sievers7ff95542012-05-03 02:29:13 +02001186 idx = log_next(idx);
1187 seq++;
1188 }
Kay Sieverse2ae7152012-06-15 14:07:51 +02001189
1190 /* move first record forward until length fits into the buffer */
Kay Sievers7ff95542012-05-03 02:29:13 +02001191 seq = clear_seq;
1192 idx = clear_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07001193 prev = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001194 while (len > size && seq < log_next_seq) {
Joe Perches62e32ac2013-07-31 13:53:47 -07001195 struct printk_log *msg = log_from_idx(idx);
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001196
Kay Sievers5becfb12012-07-09 12:15:42 -07001197 len -= msg_print_text(msg, prev, true, NULL, 0);
Jeff Mahoneye3756472012-08-10 15:07:09 -04001198 prev = msg->flags;
Kay Sievers7ff95542012-05-03 02:29:13 +02001199 idx = log_next(idx);
1200 seq++;
1201 }
1202
Kay Sieverse2ae7152012-06-15 14:07:51 +02001203 /* last message fitting into this dump */
Kay Sievers7ff95542012-05-03 02:29:13 +02001204 next_seq = log_next_seq;
1205
1206 len = 0;
1207 while (len >= 0 && seq < next_seq) {
Joe Perches62e32ac2013-07-31 13:53:47 -07001208 struct printk_log *msg = log_from_idx(idx);
Kay Sievers7ff95542012-05-03 02:29:13 +02001209 int textlen;
1210
Kay Sievers70498252012-07-16 18:35:29 -07001211 textlen = msg_print_text(msg, prev, true, text,
1212 LOG_LINE_MAX + PREFIX_MAX);
Kay Sievers7ff95542012-05-03 02:29:13 +02001213 if (textlen < 0) {
1214 len = textlen;
1215 break;
1216 }
1217 idx = log_next(idx);
1218 seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07001219 prev = msg->flags;
Kay Sievers7ff95542012-05-03 02:29:13 +02001220
1221 raw_spin_unlock_irq(&logbuf_lock);
1222 if (copy_to_user(buf + len, text, textlen))
1223 len = -EFAULT;
1224 else
1225 len += textlen;
1226 raw_spin_lock_irq(&logbuf_lock);
1227
1228 if (seq < log_first_seq) {
1229 /* messages are gone, move to next one */
1230 seq = log_first_seq;
1231 idx = log_first_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07001232 prev = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001233 }
1234 }
1235 }
1236
1237 if (clear) {
1238 clear_seq = log_next_seq;
1239 clear_idx = log_next_idx;
1240 }
1241 raw_spin_unlock_irq(&logbuf_lock);
1242
1243 kfree(text);
1244 return len;
1245}
1246
Kees Cook00234592010-02-03 15:36:43 -08001247int do_syslog(int type, char __user *buf, int len, bool from_file)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248{
Kay Sievers7ff95542012-05-03 02:29:13 +02001249 bool clear = false;
1250 static int saved_console_loglevel = -1;
Linus Torvaldsee24aeb2011-02-10 17:53:55 -08001251 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001252
Linus Torvaldsee24aeb2011-02-10 17:53:55 -08001253 error = check_syslog_permissions(type, from_file);
1254 if (error)
1255 goto out;
Eric Paris12b30522010-11-15 18:36:29 -05001256
1257 error = security_syslog(type);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001258 if (error)
1259 return error;
1260
1261 switch (type) {
Kees Cookd78ca3c2010-02-03 15:37:13 -08001262 case SYSLOG_ACTION_CLOSE: /* Close log */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001263 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001264 case SYSLOG_ACTION_OPEN: /* Open log */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001265 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001266 case SYSLOG_ACTION_READ: /* Read from log */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001267 error = -EINVAL;
1268 if (!buf || len < 0)
1269 goto out;
1270 error = 0;
1271 if (!len)
1272 goto out;
1273 if (!access_ok(VERIFY_WRITE, buf, len)) {
1274 error = -EFAULT;
1275 goto out;
1276 }
Yuanhan Liu4a77a5a2012-06-16 21:21:51 +08001277 error = wait_event_interruptible(log_wait,
1278 syslog_seq != log_next_seq);
Kay Sieverscb424ff2012-07-06 09:50:09 -07001279 if (error)
Yuanhan Liu4a77a5a2012-06-16 21:21:51 +08001280 goto out;
Kay Sievers7ff95542012-05-03 02:29:13 +02001281 error = syslog_print(buf, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001283 /* Read/clear last kernel messages */
1284 case SYSLOG_ACTION_READ_CLEAR:
Kay Sievers7ff95542012-05-03 02:29:13 +02001285 clear = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 /* FALL THRU */
Kees Cookd78ca3c2010-02-03 15:37:13 -08001287 /* Read last kernel messages */
1288 case SYSLOG_ACTION_READ_ALL:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 error = -EINVAL;
1290 if (!buf || len < 0)
1291 goto out;
1292 error = 0;
1293 if (!len)
1294 goto out;
1295 if (!access_ok(VERIFY_WRITE, buf, len)) {
1296 error = -EFAULT;
1297 goto out;
1298 }
Kay Sievers7ff95542012-05-03 02:29:13 +02001299 error = syslog_print_all(buf, len, clear);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001300 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001301 /* Clear ring buffer */
1302 case SYSLOG_ACTION_CLEAR:
Kay Sievers7ff95542012-05-03 02:29:13 +02001303 syslog_print_all(NULL, 0, true);
Alan Stern4661e352012-06-22 17:12:19 -04001304 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001305 /* Disable logging to console */
1306 case SYSLOG_ACTION_CONSOLE_OFF:
Frans Pop1aaad492009-07-06 13:31:48 +02001307 if (saved_console_loglevel == -1)
1308 saved_console_loglevel = console_loglevel;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309 console_loglevel = minimum_console_loglevel;
1310 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001311 /* Enable logging to console */
1312 case SYSLOG_ACTION_CONSOLE_ON:
Frans Pop1aaad492009-07-06 13:31:48 +02001313 if (saved_console_loglevel != -1) {
1314 console_loglevel = saved_console_loglevel;
1315 saved_console_loglevel = -1;
1316 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001317 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001318 /* Set level of messages printed to console */
1319 case SYSLOG_ACTION_CONSOLE_LEVEL:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001320 error = -EINVAL;
1321 if (len < 1 || len > 8)
1322 goto out;
1323 if (len < minimum_console_loglevel)
1324 len = minimum_console_loglevel;
1325 console_loglevel = len;
Frans Pop1aaad492009-07-06 13:31:48 +02001326 /* Implicitly re-enable logging to console */
1327 saved_console_loglevel = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328 error = 0;
1329 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001330 /* Number of chars in the log buffer */
1331 case SYSLOG_ACTION_SIZE_UNREAD:
Kay Sievers7ff95542012-05-03 02:29:13 +02001332 raw_spin_lock_irq(&logbuf_lock);
1333 if (syslog_seq < log_first_seq) {
1334 /* messages are gone, move to first one */
1335 syslog_seq = log_first_seq;
1336 syslog_idx = log_first_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07001337 syslog_prev = 0;
Kay Sieverseb02dac2012-07-09 10:05:10 -07001338 syslog_partial = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001339 }
1340 if (from_file) {
1341 /*
1342 * Short-cut for poll(/"proc/kmsg") which simply checks
1343 * for pending data, not the size; return the count of
1344 * records, not the length.
1345 */
Alex Eldere97e1262014-08-06 16:08:59 -07001346 error = log_next_seq - syslog_seq;
Kay Sievers7ff95542012-05-03 02:29:13 +02001347 } else {
Kay Sievers5becfb12012-07-09 12:15:42 -07001348 u64 seq = syslog_seq;
1349 u32 idx = syslog_idx;
1350 enum log_flags prev = syslog_prev;
Kay Sievers7ff95542012-05-03 02:29:13 +02001351
1352 error = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02001353 while (seq < log_next_seq) {
Joe Perches62e32ac2013-07-31 13:53:47 -07001354 struct printk_log *msg = log_from_idx(idx);
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02001355
Kay Sievers5becfb12012-07-09 12:15:42 -07001356 error += msg_print_text(msg, prev, true, NULL, 0);
Kay Sievers7ff95542012-05-03 02:29:13 +02001357 idx = log_next(idx);
1358 seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07001359 prev = msg->flags;
Kay Sievers7ff95542012-05-03 02:29:13 +02001360 }
Kay Sieverseb02dac2012-07-09 10:05:10 -07001361 error -= syslog_partial;
Kay Sievers7ff95542012-05-03 02:29:13 +02001362 }
1363 raw_spin_unlock_irq(&logbuf_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -08001365 /* Size of the log buffer */
1366 case SYSLOG_ACTION_SIZE_BUFFER:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 error = log_buf_len;
1368 break;
1369 default:
1370 error = -EINVAL;
1371 break;
1372 }
1373out:
1374 return error;
1375}
1376
Heiko Carstens1e7bfb22009-01-14 14:14:29 +01001377SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378{
Kees Cook637241a2013-06-12 14:04:39 -07001379 return do_syslog(type, buf, len, SYSLOG_FROM_READER);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380}
1381
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 * Call the console drivers, asking them to write out
1384 * log_buf[start] to log_buf[end - 1].
Torben Hohnac751ef2011-01-25 15:07:35 -08001385 * The console_lock must be held.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386 */
Kay Sievers7ff95542012-05-03 02:29:13 +02001387static void call_console_drivers(int level, const char *text, size_t len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388{
Kay Sievers7ff95542012-05-03 02:29:13 +02001389 struct console *con;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390
zhangwei(Jovi)07c65f42013-04-29 16:17:16 -07001391 trace_console(text, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392
Kay Sievers7ff95542012-05-03 02:29:13 +02001393 if (level >= console_loglevel && !ignore_loglevel)
1394 return;
1395 if (!console_drivers)
1396 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397
Kay Sievers7ff95542012-05-03 02:29:13 +02001398 for_each_console(con) {
1399 if (exclusive_console && con != exclusive_console)
1400 continue;
1401 if (!(con->flags & CON_ENABLED))
1402 continue;
1403 if (!con->write)
1404 continue;
1405 if (!cpu_online(smp_processor_id()) &&
1406 !(con->flags & CON_ANYTIME))
1407 continue;
1408 con->write(con, text, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410}
1411
1412/*
1413 * Zap console related locks when oopsing. Only zap at most once
1414 * every 10 seconds, to leave time for slow consoles to print a
1415 * full oops.
1416 */
1417static void zap_locks(void)
1418{
1419 static unsigned long oops_timestamp;
1420
1421 if (time_after_eq(jiffies, oops_timestamp) &&
Jesper Juhl40dc5652005-10-30 15:02:46 -08001422 !time_after(jiffies, oops_timestamp + 30 * HZ))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 return;
1424
1425 oops_timestamp = jiffies;
1426
Peter Zijlstra94d24fc2011-06-07 11:17:30 +02001427 debug_locks_off();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 /* If a crash is occurring, make sure we can't deadlock */
Thomas Gleixner07354eb2009-07-25 17:50:36 +02001429 raw_spin_lock_init(&logbuf_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001430 /* And make sure that we print immediately */
Thomas Gleixner5b8c4f22010-09-07 14:33:43 +00001431 sema_init(&console_sem, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001432}
1433
Jan Kara608873c2014-06-04 16:11:35 -07001434/*
1435 * Check if we have any console that is capable of printing while cpu is
1436 * booting or shutting down. Requires console_sem.
1437 */
Michael Ellerman76a8ad22006-06-25 05:47:40 -07001438static int have_callable_console(void)
1439{
1440 struct console *con;
1441
Robin Getz4d091612009-07-01 21:08:37 -04001442 for_each_console(con)
Michael Ellerman76a8ad22006-06-25 05:47:40 -07001443 if (con->flags & CON_ANYTIME)
1444 return 1;
1445
1446 return 0;
1447}
1448
Linus Torvalds266c2e02008-03-24 19:25:08 -07001449/*
1450 * Can we actually use the console at this time on this cpu?
1451 *
Andrew Mortond18bbc22014-07-02 15:22:38 -07001452 * Console drivers may assume that per-cpu resources have
1453 * been allocated. So unless they're explicitly marked as
1454 * being able to cope (CON_ANYTIME) don't call them until
1455 * this CPU is officially up.
Linus Torvalds266c2e02008-03-24 19:25:08 -07001456 */
1457static inline int can_use_console(unsigned int cpu)
1458{
1459 return cpu_online(cpu) || have_callable_console();
1460}
1461
1462/*
1463 * Try to get console ownership to actually show the kernel
1464 * messages from a 'printk'. Return true (and with the
Torben Hohnac751ef2011-01-25 15:07:35 -08001465 * console_lock held, and 'console_locked' set) if it
Linus Torvalds266c2e02008-03-24 19:25:08 -07001466 * is successful, false otherwise.
Linus Torvalds266c2e02008-03-24 19:25:08 -07001467 */
Andrew Mortond18bbc22014-07-02 15:22:38 -07001468static int console_trylock_for_printk(unsigned int cpu)
Linus Torvalds266c2e02008-03-24 19:25:08 -07001469{
Jan Kara608873c2014-06-04 16:11:35 -07001470 if (!console_trylock())
1471 return 0;
1472 /*
1473 * If we can't use the console, we need to release the console
1474 * semaphore by hand to avoid flushing the buffer. We need to hold the
1475 * console semaphore in order to do this test safely.
1476 */
1477 if (!can_use_console(cpu)) {
1478 console_locked = 0;
Jan Karabd8d7cf2014-06-04 16:11:36 -07001479 up_console_sem();
Jan Kara608873c2014-06-04 16:11:35 -07001480 return 0;
1481 }
1482 return 1;
Linus Torvalds266c2e02008-03-24 19:25:08 -07001483}
Ingo Molnar32a76002008-01-25 21:07:58 +01001484
Dave Youngaf913222009-09-22 16:43:33 -07001485int printk_delay_msec __read_mostly;
1486
1487static inline void printk_delay(void)
1488{
1489 if (unlikely(printk_delay_msec)) {
1490 int m = printk_delay_msec;
1491
1492 while (m--) {
1493 mdelay(1);
1494 touch_nmi_watchdog();
1495 }
1496 }
1497}
1498
Kay Sievers084681d2012-06-28 09:38:53 +02001499/*
1500 * Continuation lines are buffered, and not committed to the record buffer
1501 * until the line is complete, or a race forces it. The line fragments
1502 * though, are printed immediately to the consoles to ensure everything has
1503 * reached the console in case of a kernel crash.
1504 */
1505static struct cont {
1506 char buf[LOG_LINE_MAX];
1507 size_t len; /* length == 0 means unused buffer */
1508 size_t cons; /* bytes written to console */
1509 struct task_struct *owner; /* task of first print*/
1510 u64 ts_nsec; /* time of first print */
1511 u8 level; /* log level of first message */
Alex Elder0b90fec2014-08-06 16:09:03 -07001512 u8 facility; /* log facility of first message */
Kay Sieverseab07262012-07-16 18:35:30 -07001513 enum log_flags flags; /* prefix, newline flags */
Kay Sievers084681d2012-06-28 09:38:53 +02001514 bool flushed:1; /* buffer sealed and committed */
1515} cont;
1516
Kay Sievers70498252012-07-16 18:35:29 -07001517static void cont_flush(enum log_flags flags)
Kay Sievers084681d2012-06-28 09:38:53 +02001518{
1519 if (cont.flushed)
1520 return;
1521 if (cont.len == 0)
1522 return;
1523
Kay Sieverseab07262012-07-16 18:35:30 -07001524 if (cont.cons) {
1525 /*
1526 * If a fragment of this line was directly flushed to the
1527 * console; wait for the console to pick up the rest of the
1528 * line. LOG_NOCONS suppresses a duplicated output.
1529 */
1530 log_store(cont.facility, cont.level, flags | LOG_NOCONS,
1531 cont.ts_nsec, NULL, 0, cont.buf, cont.len);
1532 cont.flags = flags;
1533 cont.flushed = true;
1534 } else {
1535 /*
1536 * If no fragment of this line ever reached the console,
1537 * just submit it to the store and free the buffer.
1538 */
1539 log_store(cont.facility, cont.level, flags, 0,
1540 NULL, 0, cont.buf, cont.len);
1541 cont.len = 0;
1542 }
Kay Sievers084681d2012-06-28 09:38:53 +02001543}
1544
1545static bool cont_add(int facility, int level, const char *text, size_t len)
1546{
1547 if (cont.len && cont.flushed)
1548 return false;
1549
1550 if (cont.len + len > sizeof(cont.buf)) {
Kay Sievers70498252012-07-16 18:35:29 -07001551 /* the line gets too long, split it up in separate records */
1552 cont_flush(LOG_CONT);
Kay Sievers084681d2012-06-28 09:38:53 +02001553 return false;
1554 }
1555
1556 if (!cont.len) {
1557 cont.facility = facility;
1558 cont.level = level;
1559 cont.owner = current;
1560 cont.ts_nsec = local_clock();
Kay Sieverseab07262012-07-16 18:35:30 -07001561 cont.flags = 0;
Kay Sievers084681d2012-06-28 09:38:53 +02001562 cont.cons = 0;
1563 cont.flushed = false;
1564 }
1565
1566 memcpy(cont.buf + cont.len, text, len);
1567 cont.len += len;
Kay Sieverseab07262012-07-16 18:35:30 -07001568
1569 if (cont.len > (sizeof(cont.buf) * 80) / 100)
1570 cont_flush(LOG_CONT);
1571
Kay Sievers084681d2012-06-28 09:38:53 +02001572 return true;
1573}
1574
1575static size_t cont_print_text(char *text, size_t size)
1576{
1577 size_t textlen = 0;
1578 size_t len;
1579
Kay Sieverseab07262012-07-16 18:35:30 -07001580 if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) {
Kay Sievers084681d2012-06-28 09:38:53 +02001581 textlen += print_time(cont.ts_nsec, text);
1582 size -= textlen;
1583 }
1584
1585 len = cont.len - cont.cons;
1586 if (len > 0) {
1587 if (len+1 > size)
1588 len = size-1;
1589 memcpy(text + textlen, cont.buf + cont.cons, len);
1590 textlen += len;
1591 cont.cons = cont.len;
1592 }
1593
1594 if (cont.flushed) {
Kay Sieverseab07262012-07-16 18:35:30 -07001595 if (cont.flags & LOG_NEWLINE)
1596 text[textlen++] = '\n';
Kay Sievers084681d2012-06-28 09:38:53 +02001597 /* got everything, release buffer */
1598 cont.len = 0;
1599 }
1600 return textlen;
1601}
1602
Kay Sievers7ff95542012-05-03 02:29:13 +02001603asmlinkage int vprintk_emit(int facility, int level,
1604 const char *dict, size_t dictlen,
1605 const char *fmt, va_list args)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001606{
Kay Sievers7ff95542012-05-03 02:29:13 +02001607 static int recursion_bug;
Kay Sievers7ff95542012-05-03 02:29:13 +02001608 static char textbuf[LOG_LINE_MAX];
1609 char *text = textbuf;
Steven Rostedt458df9f2014-06-04 16:11:38 -07001610 size_t text_len = 0;
Kay Sievers5becfb12012-07-09 12:15:42 -07001611 enum log_flags lflags = 0;
Nick Andrewac60ad72008-05-12 21:21:04 +02001612 unsigned long flags;
Ingo Molnar32a76002008-01-25 21:07:58 +01001613 int this_cpu;
Kay Sievers7ff95542012-05-03 02:29:13 +02001614 int printed_len = 0;
Steven Rostedt458df9f2014-06-04 16:11:38 -07001615 bool in_sched = false;
Jan Kara608873c2014-06-04 16:11:35 -07001616 /* cpu currently holding logbuf_lock in this function */
1617 static volatile unsigned int logbuf_cpu = UINT_MAX;
1618
Steven Rostedt458df9f2014-06-04 16:11:38 -07001619 if (level == SCHED_MESSAGE_LOGLEVEL) {
1620 level = -1;
1621 in_sched = true;
1622 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623
Andrew Cooks2fa72c82012-12-17 15:59:56 -08001624 boot_delay_msec(level);
Dave Youngaf913222009-09-22 16:43:33 -07001625 printk_delay();
Randy Dunlapbfe8df32007-10-16 01:23:46 -07001626
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627 /* This stops the holder of console_sem just where we want him */
Peter Zijlstra1a9a8ae2011-06-07 11:17:30 +02001628 local_irq_save(flags);
Ingo Molnar32a76002008-01-25 21:07:58 +01001629 this_cpu = smp_processor_id();
1630
1631 /*
1632 * Ouch, printk recursed into itself!
1633 */
Kay Sievers7ff95542012-05-03 02:29:13 +02001634 if (unlikely(logbuf_cpu == this_cpu)) {
Ingo Molnar32a76002008-01-25 21:07:58 +01001635 /*
1636 * If a crash is occurring during printk() on this CPU,
1637 * then try to get the crash message out but make sure
1638 * we can't deadlock. Otherwise just return to avoid the
1639 * recursion and return - but flag the recursion so that
1640 * it can be printed at the next appropriate moment:
1641 */
Peter Zijlstra94d24fc2011-06-07 11:17:30 +02001642 if (!oops_in_progress && !lockdep_recursing(current)) {
Tejun Heo3b8945e2008-05-12 21:21:04 +02001643 recursion_bug = 1;
Andrew Mortond18bbc22014-07-02 15:22:38 -07001644 goto out_restore_irqs;
Ingo Molnar32a76002008-01-25 21:07:58 +01001645 }
1646 zap_locks();
1647 }
1648
Ingo Molnara0f1ccf2006-07-03 00:24:58 -07001649 lockdep_off();
Thomas Gleixner07354eb2009-07-25 17:50:36 +02001650 raw_spin_lock(&logbuf_lock);
Kay Sievers7ff95542012-05-03 02:29:13 +02001651 logbuf_cpu = this_cpu;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652
Tejun Heo3b8945e2008-05-12 21:21:04 +02001653 if (recursion_bug) {
Kay Sievers7ff95542012-05-03 02:29:13 +02001654 static const char recursion_msg[] =
1655 "BUG: recent printk recursion!";
1656
Tejun Heo3b8945e2008-05-12 21:21:04 +02001657 recursion_bug = 0;
Petr Mladek034633c2014-06-04 16:11:33 -07001658 text_len = strlen(recursion_msg);
Kay Sievers7ff95542012-05-03 02:29:13 +02001659 /* emit KERN_CRIT message */
Petr Mladek034633c2014-06-04 16:11:33 -07001660 printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
1661 NULL, 0, recursion_msg, text_len);
Linus Torvalds5fd29d62009-06-16 10:57:02 -07001662 }
1663
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 /*
Kay Sievers7ff95542012-05-03 02:29:13 +02001665 * The printf needs to come first; we need the syslog
1666 * prefix which might be passed-in as a parameter.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001667 */
Steven Rostedt458df9f2014-06-04 16:11:38 -07001668 if (in_sched)
1669 text_len = scnprintf(text, sizeof(textbuf),
1670 KERN_WARNING "[sched_delayed] ");
1671
1672 text_len += vscnprintf(text + text_len,
1673 sizeof(textbuf) - text_len, fmt, args);
Nick Andrewac60ad72008-05-12 21:21:04 +02001674
Kay Sievers7ff95542012-05-03 02:29:13 +02001675 /* mark and strip a trailing newline */
Kay Sieversc313af12012-05-14 20:46:27 +02001676 if (text_len && text[text_len-1] == '\n') {
1677 text_len--;
Kay Sievers5becfb12012-07-09 12:15:42 -07001678 lflags |= LOG_NEWLINE;
Kay Sievers7ff95542012-05-03 02:29:13 +02001679 }
Kay Sievers9d90c8d2011-03-13 03:19:51 +01001680
Joe Perches088a52a2012-07-30 14:40:19 -07001681 /* strip kernel syslog prefix and extract log level or control flags */
1682 if (facility == 0) {
1683 int kern_level = printk_get_level(text);
1684
1685 if (kern_level) {
1686 const char *end_of_header = printk_skip_level(text);
1687 switch (kern_level) {
1688 case '0' ... '7':
1689 if (level == -1)
1690 level = kern_level - '0';
1691 case 'd': /* KERN_DEFAULT */
1692 lflags |= LOG_PREFIX;
Joe Perches088a52a2012-07-30 14:40:19 -07001693 }
Petr Mladeke8c42d32014-04-03 14:48:41 -07001694 /*
1695 * No need to check length here because vscnprintf
1696 * put '\0' at the end of the string. Only valid and
1697 * newly printed level is detected.
1698 */
Joe Perches088a52a2012-07-30 14:40:19 -07001699 text_len -= end_of_header - text;
1700 text = (char *)end_of_header;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001701 }
Kay Sievers7ff95542012-05-03 02:29:13 +02001702 }
Nick Andrewac60ad72008-05-12 21:21:04 +02001703
Kay Sieversc313af12012-05-14 20:46:27 +02001704 if (level == -1)
1705 level = default_message_loglevel;
1706
Kay Sievers5becfb12012-07-09 12:15:42 -07001707 if (dict)
1708 lflags |= LOG_PREFIX|LOG_NEWLINE;
Kay Sievers7ff95542012-05-03 02:29:13 +02001709
Kay Sievers5becfb12012-07-09 12:15:42 -07001710 if (!(lflags & LOG_NEWLINE)) {
Kay Sievers084681d2012-06-28 09:38:53 +02001711 /*
1712 * Flush the conflicting buffer. An earlier newline was missing,
1713 * or another task also prints continuation lines.
1714 */
Kay Sievers5becfb12012-07-09 12:15:42 -07001715 if (cont.len && (lflags & LOG_PREFIX || cont.owner != current))
Kay Sieverseab07262012-07-16 18:35:30 -07001716 cont_flush(LOG_NEWLINE);
Kay Sieversc313af12012-05-14 20:46:27 +02001717
Kay Sievers084681d2012-06-28 09:38:53 +02001718 /* buffer line if possible, otherwise store it right away */
Petr Mladek034633c2014-06-04 16:11:33 -07001719 if (cont_add(facility, level, text, text_len))
1720 printed_len += text_len;
1721 else
1722 printed_len += log_store(facility, level,
1723 lflags | LOG_CONT, 0,
1724 dict, dictlen, text, text_len);
Kay Sievers084681d2012-06-28 09:38:53 +02001725 } else {
1726 bool stored = false;
1727
1728 /*
Steven Rostedtd3620822012-06-29 11:40:11 -04001729 * If an earlier newline was missing and it was the same task,
1730 * either merge it with the current buffer and flush, or if
1731 * there was a race with interrupts (prefix == true) then just
1732 * flush it out and store this line separately.
Arun KS1d3fa372014-01-23 15:54:19 -08001733 * If the preceding printk was from a different task and missed
1734 * a newline, flush and append the newline.
Kay Sievers084681d2012-06-28 09:38:53 +02001735 */
Arun KS1d3fa372014-01-23 15:54:19 -08001736 if (cont.len) {
1737 if (cont.owner == current && !(lflags & LOG_PREFIX))
1738 stored = cont_add(facility, level, text,
1739 text_len);
Kay Sieverseab07262012-07-16 18:35:30 -07001740 cont_flush(LOG_NEWLINE);
Kay Sieversc313af12012-05-14 20:46:27 +02001741 }
Kay Sievers084681d2012-06-28 09:38:53 +02001742
Petr Mladek034633c2014-06-04 16:11:33 -07001743 if (stored)
1744 printed_len += text_len;
1745 else
1746 printed_len += log_store(facility, level, lflags, 0,
1747 dict, dictlen, text, text_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748 }
1749
Jan Kara608873c2014-06-04 16:11:35 -07001750 logbuf_cpu = UINT_MAX;
1751 raw_spin_unlock(&logbuf_lock);
Jan Kara939f04b2014-06-04 16:11:37 -07001752
Steven Rostedt458df9f2014-06-04 16:11:38 -07001753 /* If called from the scheduler, we can not call up(). */
Andrew Mortond18bbc22014-07-02 15:22:38 -07001754 if (!in_sched) {
1755 /*
1756 * Try to acquire and then immediately release the console
1757 * semaphore. The release will print out buffers and wake up
1758 * /dev/kmsg and syslog() users.
1759 */
1760 if (console_trylock_for_printk(this_cpu))
1761 console_unlock();
1762 }
Steven Rostedt458df9f2014-06-04 16:11:38 -07001763
Andrew Mortond18bbc22014-07-02 15:22:38 -07001764 lockdep_on();
1765out_restore_irqs:
1766 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767 return printed_len;
1768}
Kay Sievers7ff95542012-05-03 02:29:13 +02001769EXPORT_SYMBOL(vprintk_emit);
1770
1771asmlinkage int vprintk(const char *fmt, va_list args)
1772{
1773 return vprintk_emit(0, -1, NULL, 0, fmt, args);
1774}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001775EXPORT_SYMBOL(vprintk);
1776
Kay Sievers7ff95542012-05-03 02:29:13 +02001777asmlinkage int printk_emit(int facility, int level,
1778 const char *dict, size_t dictlen,
1779 const char *fmt, ...)
1780{
1781 va_list args;
1782 int r;
1783
1784 va_start(args, fmt);
1785 r = vprintk_emit(facility, level, dict, dictlen, fmt, args);
1786 va_end(args);
1787
1788 return r;
1789}
1790EXPORT_SYMBOL(printk_emit);
1791
1792/**
1793 * printk - print a kernel message
1794 * @fmt: format string
1795 *
1796 * This is printk(). It can be called from any context. We want it to work.
1797 *
1798 * We try to grab the console_lock. If we succeed, it's easy - we log the
1799 * output and call the console drivers. If we fail to get the semaphore, we
1800 * place the output into the log buffer and return. The current holder of
1801 * the console_sem will notice the new output in console_unlock(); and will
1802 * send it to the consoles before releasing the lock.
1803 *
1804 * One effect of this deferred printing is that code which calls printk() and
1805 * then changes console_loglevel may break. This is because console_loglevel
1806 * is inspected when the actual printing occurs.
1807 *
1808 * See also:
1809 * printf(3)
1810 *
1811 * See the vsnprintf() documentation for format string extensions over C99.
1812 */
Andi Kleen722a9f92014-05-02 00:44:38 +02001813asmlinkage __visible int printk(const char *fmt, ...)
Kay Sievers7ff95542012-05-03 02:29:13 +02001814{
1815 va_list args;
1816 int r;
1817
1818#ifdef CONFIG_KGDB_KDB
1819 if (unlikely(kdb_trap_printk)) {
1820 va_start(args, fmt);
1821 r = vkdb_printf(fmt, args);
1822 va_end(args);
1823 return r;
1824 }
1825#endif
1826 va_start(args, fmt);
1827 r = vprintk_emit(0, -1, NULL, 0, fmt, args);
1828 va_end(args);
1829
1830 return r;
1831}
1832EXPORT_SYMBOL(printk);
Kay Sievers7f3a7812012-05-09 01:37:51 +02001833
Kay Sievers96efedf2012-07-16 18:35:29 -07001834#else /* CONFIG_PRINTK */
Matt Mackalld59745c2005-05-01 08:59:02 -07001835
Kay Sievers70498252012-07-16 18:35:29 -07001836#define LOG_LINE_MAX 0
1837#define PREFIX_MAX 0
Kay Sievers7f3a7812012-05-09 01:37:51 +02001838#define LOG_LINE_MAX 0
Kay Sievers96efedf2012-07-16 18:35:29 -07001839static u64 syslog_seq;
1840static u32 syslog_idx;
Kay Sieverseab07262012-07-16 18:35:30 -07001841static u64 console_seq;
1842static u32 console_idx;
Kay Sievers96efedf2012-07-16 18:35:29 -07001843static enum log_flags syslog_prev;
1844static u64 log_first_seq;
1845static u32 log_first_idx;
1846static u64 log_next_seq;
Kay Sieverseab07262012-07-16 18:35:30 -07001847static enum log_flags console_prev;
Kay Sievers084681d2012-06-28 09:38:53 +02001848static struct cont {
1849 size_t len;
1850 size_t cons;
1851 u8 level;
1852 bool flushed:1;
1853} cont;
Joe Perches62e32ac2013-07-31 13:53:47 -07001854static struct printk_log *log_from_idx(u32 idx) { return NULL; }
Kay Sievers7f3a7812012-05-09 01:37:51 +02001855static u32 log_next(u32 idx) { return 0; }
Kay Sievers7f3a7812012-05-09 01:37:51 +02001856static void call_console_drivers(int level, const char *text, size_t len) {}
Joe Perches62e32ac2013-07-31 13:53:47 -07001857static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev,
Kay Sievers5becfb12012-07-09 12:15:42 -07001858 bool syslog, char *buf, size_t size) { return 0; }
Kay Sievers084681d2012-06-28 09:38:53 +02001859static size_t cont_print_text(char *text, size_t size) { return 0; }
Matt Mackalld59745c2005-05-01 08:59:02 -07001860
Kay Sievers7f3a7812012-05-09 01:37:51 +02001861#endif /* CONFIG_PRINTK */
Matt Mackalld59745c2005-05-01 08:59:02 -07001862
Thomas Gleixnerd0380e62013-04-29 16:17:18 -07001863#ifdef CONFIG_EARLY_PRINTK
1864struct console *early_console;
1865
1866void early_vprintk(const char *fmt, va_list ap)
1867{
1868 if (early_console) {
1869 char buf[512];
1870 int n = vscnprintf(buf, sizeof(buf), fmt, ap);
1871
1872 early_console->write(early_console, buf, n);
1873 }
1874}
1875
Andi Kleen722a9f92014-05-02 00:44:38 +02001876asmlinkage __visible void early_printk(const char *fmt, ...)
Thomas Gleixnerd0380e62013-04-29 16:17:18 -07001877{
1878 va_list ap;
1879
1880 va_start(ap, fmt);
1881 early_vprintk(fmt, ap);
1882 va_end(ap);
1883}
1884#endif
1885
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001886static int __add_preferred_console(char *name, int idx, char *options,
1887 char *brl_options)
1888{
1889 struct console_cmdline *c;
1890 int i;
1891
1892 /*
1893 * See if this tty is not yet registered, and
1894 * if we have a slot free.
1895 */
Joe Perches23475402013-07-31 13:53:46 -07001896 for (i = 0, c = console_cmdline;
1897 i < MAX_CMDLINECONSOLES && c->name[0];
1898 i++, c++) {
1899 if (strcmp(c->name, name) == 0 && c->index == idx) {
1900 if (!brl_options)
1901 selected_console = i;
1902 return 0;
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001903 }
Joe Perches23475402013-07-31 13:53:46 -07001904 }
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001905 if (i == MAX_CMDLINECONSOLES)
1906 return -E2BIG;
1907 if (!brl_options)
1908 selected_console = i;
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001909 strlcpy(c->name, name, sizeof(c->name));
1910 c->options = options;
Joe Perchesbbeddf52013-07-31 13:53:45 -07001911 braille_set_options(c, brl_options);
1912
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001913 c->index = idx;
1914 return 0;
1915}
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001916/*
Alex Elder0b90fec2014-08-06 16:09:03 -07001917 * Set up a console. Called via do_early_param() in init/main.c
1918 * for each "console=" parameter in the boot command line.
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001919 */
1920static int __init console_setup(char *str)
1921{
Alex Elder0b90fec2014-08-06 16:09:03 -07001922 char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001923 char *s, *options, *brl_options = NULL;
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001924 int idx;
1925
Joe Perchesbbeddf52013-07-31 13:53:45 -07001926 if (_braille_console_setup(&str, &brl_options))
1927 return 1;
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001928
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001929 /*
1930 * Decode str into name, index, options.
1931 */
1932 if (str[0] >= '0' && str[0] <= '9') {
Yinghai Lueaa944a2007-07-15 23:37:27 -07001933 strcpy(buf, "ttyS");
1934 strncpy(buf + 4, str, sizeof(buf) - 5);
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001935 } else {
Yinghai Lueaa944a2007-07-15 23:37:27 -07001936 strncpy(buf, str, sizeof(buf) - 1);
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001937 }
Yinghai Lueaa944a2007-07-15 23:37:27 -07001938 buf[sizeof(buf) - 1] = 0;
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001939 if ((options = strchr(str, ',')) != NULL)
1940 *(options++) = 0;
1941#ifdef __sparc__
1942 if (!strcmp(str, "ttya"))
Yinghai Lueaa944a2007-07-15 23:37:27 -07001943 strcpy(buf, "ttyS0");
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001944 if (!strcmp(str, "ttyb"))
Yinghai Lueaa944a2007-07-15 23:37:27 -07001945 strcpy(buf, "ttyS1");
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001946#endif
Yinghai Lueaa944a2007-07-15 23:37:27 -07001947 for (s = buf; *s; s++)
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001948 if ((*s >= '0' && *s <= '9') || *s == ',')
1949 break;
1950 idx = simple_strtoul(s, NULL, 10);
1951 *s = 0;
1952
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001953 __add_preferred_console(buf, idx, options, brl_options);
Markus Armbruster9e124fe2008-05-26 23:31:07 +01001954 console_set_on_cmdline = 1;
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001955 return 1;
1956}
1957__setup("console=", console_setup);
1958
Linus Torvalds1da177e2005-04-16 15:20:36 -07001959/**
Matt Mackall3c0547b2005-05-16 21:53:47 -07001960 * add_preferred_console - add a device to the list of preferred consoles.
Martin Waitzddad86c2005-11-13 16:08:14 -08001961 * @name: device name
1962 * @idx: device index
1963 * @options: options for this console
Matt Mackall3c0547b2005-05-16 21:53:47 -07001964 *
1965 * The last preferred console added will be used for kernel messages
1966 * and stdin/out/err for init. Normally this is used by console_setup
1967 * above to handle user-supplied console arguments; however it can also
1968 * be used by arch-specific code either to override the user or more
1969 * commonly to provide a default console (ie from PROM variables) when
1970 * the user has not supplied one.
1971 */
David S. Millerfb445ee2007-12-29 01:19:49 -08001972int add_preferred_console(char *name, int idx, char *options)
Matt Mackall3c0547b2005-05-16 21:53:47 -07001973{
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001974 return __add_preferred_console(name, idx, options, NULL);
Matt Mackall3c0547b2005-05-16 21:53:47 -07001975}
1976
Daniel Ritzb6b1d872007-08-03 16:07:43 +02001977int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
Yinghai Lu18a8bd92007-07-15 23:37:59 -07001978{
1979 struct console_cmdline *c;
1980 int i;
1981
Joe Perches23475402013-07-31 13:53:46 -07001982 for (i = 0, c = console_cmdline;
1983 i < MAX_CMDLINECONSOLES && c->name[0];
1984 i++, c++)
1985 if (strcmp(c->name, name) == 0 && c->index == idx) {
1986 strlcpy(c->name, name_new, sizeof(c->name));
1987 c->name[sizeof(c->name) - 1] = 0;
1988 c->options = options;
1989 c->index = idx_new;
1990 return i;
Yinghai Lu18a8bd92007-07-15 23:37:59 -07001991 }
1992 /* not found */
1993 return -1;
1994}
1995
Rusty Russell2329abf2012-01-13 09:32:18 +10301996bool console_suspend_enabled = 1;
Andres Salomon8f4ce8c2007-10-18 03:04:50 -07001997EXPORT_SYMBOL(console_suspend_enabled);
1998
1999static int __init console_suspend_disable(char *str)
2000{
2001 console_suspend_enabled = 0;
2002 return 1;
2003}
2004__setup("no_console_suspend", console_suspend_disable);
Yanmin Zhang134620f2011-10-31 17:11:27 -07002005module_param_named(console_suspend, console_suspend_enabled,
2006 bool, S_IRUGO | S_IWUSR);
2007MODULE_PARM_DESC(console_suspend, "suspend console during suspend"
2008 " and hibernate operations");
Andres Salomon8f4ce8c2007-10-18 03:04:50 -07002009
Matt Mackall3c0547b2005-05-16 21:53:47 -07002010/**
Linus Torvalds557240b2006-06-19 18:16:01 -07002011 * suspend_console - suspend the console subsystem
2012 *
2013 * This disables printk() while we go into suspend states
2014 */
2015void suspend_console(void)
2016{
Andres Salomon8f4ce8c2007-10-18 03:04:50 -07002017 if (!console_suspend_enabled)
2018 return;
Pavel Machek0d630812008-07-23 21:28:32 -07002019 printk("Suspending console(s) (use no_console_suspend to debug)\n");
Torben Hohnac751ef2011-01-25 15:07:35 -08002020 console_lock();
Linus Torvalds557240b2006-06-19 18:16:01 -07002021 console_suspended = 1;
Jan Karabd8d7cf2014-06-04 16:11:36 -07002022 up_console_sem();
Linus Torvalds557240b2006-06-19 18:16:01 -07002023}
2024
2025void resume_console(void)
2026{
Andres Salomon8f4ce8c2007-10-18 03:04:50 -07002027 if (!console_suspend_enabled)
2028 return;
Jan Karabd8d7cf2014-06-04 16:11:36 -07002029 down_console_sem();
Linus Torvalds557240b2006-06-19 18:16:01 -07002030 console_suspended = 0;
Torben Hohnac751ef2011-01-25 15:07:35 -08002031 console_unlock();
Linus Torvalds557240b2006-06-19 18:16:01 -07002032}
2033
2034/**
Kevin Cernekee034260d2010-06-03 22:11:25 -07002035 * console_cpu_notify - print deferred console messages after CPU hotplug
2036 * @self: notifier struct
2037 * @action: CPU hotplug event
2038 * @hcpu: unused
2039 *
2040 * If printk() is called from a CPU that is not online yet, the messages
2041 * will be spooled but will not show up on the console. This function is
2042 * called when a new CPU comes online (or fails to come up), and ensures
2043 * that any such output gets printed.
2044 */
Paul Gortmaker0db06282013-06-19 14:53:51 -04002045static int console_cpu_notify(struct notifier_block *self,
Kevin Cernekee034260d2010-06-03 22:11:25 -07002046 unsigned long action, void *hcpu)
2047{
2048 switch (action) {
2049 case CPU_ONLINE:
2050 case CPU_DEAD:
Kevin Cernekee034260d2010-06-03 22:11:25 -07002051 case CPU_DOWN_FAILED:
2052 case CPU_UP_CANCELED:
Torben Hohnac751ef2011-01-25 15:07:35 -08002053 console_lock();
2054 console_unlock();
Kevin Cernekee034260d2010-06-03 22:11:25 -07002055 }
2056 return NOTIFY_OK;
2057}
2058
2059/**
Torben Hohnac751ef2011-01-25 15:07:35 -08002060 * console_lock - lock the console system for exclusive use.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002061 *
Torben Hohnac751ef2011-01-25 15:07:35 -08002062 * Acquires a lock which guarantees that the caller has
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063 * exclusive access to the console system and the console_drivers list.
2064 *
2065 * Can sleep, returns nothing.
2066 */
Torben Hohnac751ef2011-01-25 15:07:35 -08002067void console_lock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068{
Daniel Vetter6b898c02012-09-17 23:03:31 +00002069 might_sleep();
2070
Jan Karabd8d7cf2014-06-04 16:11:36 -07002071 down_console_sem();
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01002072 if (console_suspended)
2073 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002074 console_locked = 1;
2075 console_may_schedule = 1;
2076}
Torben Hohnac751ef2011-01-25 15:07:35 -08002077EXPORT_SYMBOL(console_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078
Torben Hohnac751ef2011-01-25 15:07:35 -08002079/**
2080 * console_trylock - try to lock the console system for exclusive use.
2081 *
Alex Elder0b90fec2014-08-06 16:09:03 -07002082 * Try to acquire a lock which guarantees that the caller has exclusive
2083 * access to the console system and the console_drivers list.
Torben Hohnac751ef2011-01-25 15:07:35 -08002084 *
2085 * returns 1 on success, and 0 on failure to acquire the lock.
2086 */
2087int console_trylock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002088{
Jan Karabd8d7cf2014-06-04 16:11:36 -07002089 if (down_trylock_console_sem())
Torben Hohnac751ef2011-01-25 15:07:35 -08002090 return 0;
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01002091 if (console_suspended) {
Jan Karabd8d7cf2014-06-04 16:11:36 -07002092 up_console_sem();
Torben Hohnac751ef2011-01-25 15:07:35 -08002093 return 0;
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01002094 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002095 console_locked = 1;
2096 console_may_schedule = 0;
Torben Hohnac751ef2011-01-25 15:07:35 -08002097 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002098}
Torben Hohnac751ef2011-01-25 15:07:35 -08002099EXPORT_SYMBOL(console_trylock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002100
2101int is_console_locked(void)
2102{
2103 return console_locked;
2104}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002105
Kay Sieverseab07262012-07-16 18:35:30 -07002106static void console_cont_flush(char *text, size_t size)
2107{
2108 unsigned long flags;
2109 size_t len;
2110
2111 raw_spin_lock_irqsave(&logbuf_lock, flags);
2112
2113 if (!cont.len)
2114 goto out;
2115
2116 /*
2117 * We still queue earlier records, likely because the console was
2118 * busy. The earlier ones need to be printed before this one, we
2119 * did not flush any fragment so far, so just let it queue up.
2120 */
2121 if (console_seq < log_next_seq && !cont.cons)
2122 goto out;
2123
2124 len = cont_print_text(text, size);
2125 raw_spin_unlock(&logbuf_lock);
2126 stop_critical_timings();
2127 call_console_drivers(cont.level, text, len);
2128 start_critical_timings();
2129 local_irq_restore(flags);
2130 return;
2131out:
2132 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2133}
Kay Sievers7ff95542012-05-03 02:29:13 +02002134
Linus Torvalds1da177e2005-04-16 15:20:36 -07002135/**
Torben Hohnac751ef2011-01-25 15:07:35 -08002136 * console_unlock - unlock the console system
Linus Torvalds1da177e2005-04-16 15:20:36 -07002137 *
Torben Hohnac751ef2011-01-25 15:07:35 -08002138 * Releases the console_lock which the caller holds on the console system
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139 * and the console driver list.
2140 *
Torben Hohnac751ef2011-01-25 15:07:35 -08002141 * While the console_lock was held, console output may have been buffered
2142 * by printk(). If this is the case, console_unlock(); emits
2143 * the output prior to releasing the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002144 *
Kay Sievers7f3a7812012-05-09 01:37:51 +02002145 * If there is output waiting, we wake /dev/kmsg and syslog() users.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 *
Torben Hohnac751ef2011-01-25 15:07:35 -08002147 * console_unlock(); may be called from any context.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002148 */
Torben Hohnac751ef2011-01-25 15:07:35 -08002149void console_unlock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150{
Kay Sievers70498252012-07-16 18:35:29 -07002151 static char text[LOG_LINE_MAX + PREFIX_MAX];
Kay Sievers7ff95542012-05-03 02:29:13 +02002152 static u64 seen_seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153 unsigned long flags;
Kay Sievers7ff95542012-05-03 02:29:13 +02002154 bool wake_klogd = false;
2155 bool retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002156
Linus Torvalds557240b2006-06-19 18:16:01 -07002157 if (console_suspended) {
Jan Karabd8d7cf2014-06-04 16:11:36 -07002158 up_console_sem();
Linus Torvalds557240b2006-06-19 18:16:01 -07002159 return;
2160 }
Antonino A. Daplas78944e52006-08-05 12:14:16 -07002161
2162 console_may_schedule = 0;
2163
Kay Sievers084681d2012-06-28 09:38:53 +02002164 /* flush buffered message fragment immediately to console */
Kay Sieverseab07262012-07-16 18:35:30 -07002165 console_cont_flush(text, sizeof(text));
Peter Zijlstra4f2a8d32011-06-22 11:20:09 +02002166again:
Kay Sievers7ff95542012-05-03 02:29:13 +02002167 for (;;) {
Joe Perches62e32ac2013-07-31 13:53:47 -07002168 struct printk_log *msg;
Kay Sievers3ce9a7c2012-05-13 23:30:46 +02002169 size_t len;
Kay Sievers7ff95542012-05-03 02:29:13 +02002170 int level;
2171
Thomas Gleixner07354eb2009-07-25 17:50:36 +02002172 raw_spin_lock_irqsave(&logbuf_lock, flags);
Kay Sievers7ff95542012-05-03 02:29:13 +02002173 if (seen_seq != log_next_seq) {
2174 wake_klogd = true;
2175 seen_seq = log_next_seq;
2176 }
2177
2178 if (console_seq < log_first_seq) {
Will Deacon84b5ec82014-06-04 16:11:45 -07002179 len = sprintf(text, "** %u printk messages dropped ** ",
2180 (unsigned)(log_first_seq - console_seq));
2181
Kay Sievers7ff95542012-05-03 02:29:13 +02002182 /* messages are gone, move to first one */
2183 console_seq = log_first_seq;
2184 console_idx = log_first_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07002185 console_prev = 0;
Will Deacon84b5ec82014-06-04 16:11:45 -07002186 } else {
2187 len = 0;
Kay Sievers7ff95542012-05-03 02:29:13 +02002188 }
Kay Sievers084681d2012-06-28 09:38:53 +02002189skip:
Kay Sievers7ff95542012-05-03 02:29:13 +02002190 if (console_seq == log_next_seq)
2191 break;
2192
2193 msg = log_from_idx(console_idx);
Kay Sievers084681d2012-06-28 09:38:53 +02002194 if (msg->flags & LOG_NOCONS) {
2195 /*
2196 * Skip record we have buffered and already printed
2197 * directly to the console when we received it.
2198 */
2199 console_idx = log_next(console_idx);
2200 console_seq++;
Kay Sievers68b65072012-07-06 09:50:09 -07002201 /*
2202 * We will get here again when we register a new
2203 * CON_PRINTBUFFER console. Clear the flag so we
2204 * will properly dump everything later.
2205 */
2206 msg->flags &= ~LOG_NOCONS;
Kay Sieverseab07262012-07-16 18:35:30 -07002207 console_prev = msg->flags;
Kay Sievers084681d2012-06-28 09:38:53 +02002208 goto skip;
2209 }
Kay Sievers649e6ee2012-05-10 04:30:45 +02002210
Kay Sievers084681d2012-06-28 09:38:53 +02002211 level = msg->level;
Will Deacon84b5ec82014-06-04 16:11:45 -07002212 len += msg_print_text(msg, console_prev, false,
2213 text + len, sizeof(text) - len);
Kay Sievers7ff95542012-05-03 02:29:13 +02002214 console_idx = log_next(console_idx);
2215 console_seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07002216 console_prev = msg->flags;
Thomas Gleixner07354eb2009-07-25 17:50:36 +02002217 raw_spin_unlock(&logbuf_lock);
Kay Sievers7ff95542012-05-03 02:29:13 +02002218
Steven Rostedt81d68a92008-05-12 21:20:42 +02002219 stop_critical_timings(); /* don't trace print latency */
Kay Sievers7ff95542012-05-03 02:29:13 +02002220 call_console_drivers(level, text, len);
Steven Rostedt81d68a92008-05-12 21:20:42 +02002221 start_critical_timings();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002222 local_irq_restore(flags);
2223 }
2224 console_locked = 0;
Feng Tangfe3d8ad2011-03-22 16:34:21 -07002225
2226 /* Release the exclusive_console once it is used */
2227 if (unlikely(exclusive_console))
2228 exclusive_console = NULL;
2229
Thomas Gleixner07354eb2009-07-25 17:50:36 +02002230 raw_spin_unlock(&logbuf_lock);
Peter Zijlstra4f2a8d32011-06-22 11:20:09 +02002231
Jan Karabd8d7cf2014-06-04 16:11:36 -07002232 up_console_sem();
Peter Zijlstra4f2a8d32011-06-22 11:20:09 +02002233
2234 /*
2235 * Someone could have filled up the buffer again, so re-check if there's
2236 * something to flush. In case we cannot trylock the console_sem again,
2237 * there's a new owner and the console_unlock() from them will do the
2238 * flush, no worries.
2239 */
Thomas Gleixner07354eb2009-07-25 17:50:36 +02002240 raw_spin_lock(&logbuf_lock);
Kay Sievers7ff95542012-05-03 02:29:13 +02002241 retry = console_seq != log_next_seq;
Peter Zijlstra09dc3cf2011-12-08 14:34:13 -08002242 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2243
Peter Zijlstra4f2a8d32011-06-22 11:20:09 +02002244 if (retry && console_trylock())
2245 goto again;
2246
Kirill Korotaeve3e8a752007-02-10 01:46:19 -08002247 if (wake_klogd)
2248 wake_up_klogd();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002249}
Torben Hohnac751ef2011-01-25 15:07:35 -08002250EXPORT_SYMBOL(console_unlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002251
Martin Waitzddad86c2005-11-13 16:08:14 -08002252/**
2253 * console_conditional_schedule - yield the CPU if required
Linus Torvalds1da177e2005-04-16 15:20:36 -07002254 *
2255 * If the console code is currently allowed to sleep, and
2256 * if this CPU should yield the CPU to another task, do
2257 * so here.
2258 *
Torben Hohnac751ef2011-01-25 15:07:35 -08002259 * Must be called within console_lock();.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002260 */
2261void __sched console_conditional_schedule(void)
2262{
2263 if (console_may_schedule)
2264 cond_resched();
2265}
2266EXPORT_SYMBOL(console_conditional_schedule);
2267
Linus Torvalds1da177e2005-04-16 15:20:36 -07002268void console_unblank(void)
2269{
2270 struct console *c;
2271
2272 /*
2273 * console_unblank can no longer be called in interrupt context unless
2274 * oops_in_progress is set to 1..
2275 */
2276 if (oops_in_progress) {
Jan Karabd8d7cf2014-06-04 16:11:36 -07002277 if (down_trylock_console_sem() != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002278 return;
2279 } else
Torben Hohnac751ef2011-01-25 15:07:35 -08002280 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002281
2282 console_locked = 1;
2283 console_may_schedule = 0;
Robin Getz4d091612009-07-01 21:08:37 -04002284 for_each_console(c)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002285 if ((c->flags & CON_ENABLED) && c->unblank)
2286 c->unblank();
Torben Hohnac751ef2011-01-25 15:07:35 -08002287 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002288}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002289
2290/*
2291 * Return the console tty driver structure and its associated index
2292 */
2293struct tty_driver *console_device(int *index)
2294{
2295 struct console *c;
2296 struct tty_driver *driver = NULL;
2297
Torben Hohnac751ef2011-01-25 15:07:35 -08002298 console_lock();
Robin Getz4d091612009-07-01 21:08:37 -04002299 for_each_console(c) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002300 if (!c->device)
2301 continue;
2302 driver = c->device(c, index);
2303 if (driver)
2304 break;
2305 }
Torben Hohnac751ef2011-01-25 15:07:35 -08002306 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002307 return driver;
2308}
2309
2310/*
2311 * Prevent further output on the passed console device so that (for example)
2312 * serial drivers can disable console output before suspending a port, and can
2313 * re-enable output afterwards.
2314 */
2315void console_stop(struct console *console)
2316{
Torben Hohnac751ef2011-01-25 15:07:35 -08002317 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318 console->flags &= ~CON_ENABLED;
Torben Hohnac751ef2011-01-25 15:07:35 -08002319 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002320}
2321EXPORT_SYMBOL(console_stop);
2322
2323void console_start(struct console *console)
2324{
Torben Hohnac751ef2011-01-25 15:07:35 -08002325 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002326 console->flags |= CON_ENABLED;
Torben Hohnac751ef2011-01-25 15:07:35 -08002327 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002328}
2329EXPORT_SYMBOL(console_start);
2330
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -07002331static int __read_mostly keep_bootcon;
2332
2333static int __init keep_bootcon_setup(char *str)
2334{
2335 keep_bootcon = 1;
Andrew Morton27083ba2013-11-12 15:08:50 -08002336 pr_info("debug: skip boot console de-registration.\n");
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -07002337
2338 return 0;
2339}
2340
2341early_param("keep_bootcon", keep_bootcon_setup);
2342
Linus Torvalds1da177e2005-04-16 15:20:36 -07002343/*
2344 * The console driver calls this routine during kernel initialization
2345 * to register the console printing procedure with printk() and to
2346 * print any messages that were printed by the kernel before the
2347 * console driver was initialized.
Robin Getz4d091612009-07-01 21:08:37 -04002348 *
2349 * This can happen pretty early during the boot process (because of
2350 * early_printk) - sometimes before setup_arch() completes - be careful
2351 * of what kernel features are used - they may not be initialised yet.
2352 *
2353 * There are two types of consoles - bootconsoles (early_printk) and
2354 * "real" consoles (everything which is not a bootconsole) which are
2355 * handled differently.
2356 * - Any number of bootconsoles can be registered at any time.
2357 * - As soon as a "real" console is registered, all bootconsoles
2358 * will be unregistered automatically.
2359 * - Once a "real" console is registered, any attempt to register a
2360 * bootconsoles will be rejected
Linus Torvalds1da177e2005-04-16 15:20:36 -07002361 */
Robin Getz4d091612009-07-01 21:08:37 -04002362void register_console(struct console *newcon)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002363{
Jesper Juhl40dc5652005-10-30 15:02:46 -08002364 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002365 unsigned long flags;
Robin Getz4d091612009-07-01 21:08:37 -04002366 struct console *bcon = NULL;
Joe Perches23475402013-07-31 13:53:46 -07002367 struct console_cmdline *c;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002368
Andreas Bießmann16cf48a2013-08-02 12:23:34 +02002369 if (console_drivers)
2370 for_each_console(bcon)
2371 if (WARN(bcon == newcon,
2372 "console '%s%d' already registered\n",
2373 bcon->name, bcon->index))
2374 return;
2375
Robin Getz4d091612009-07-01 21:08:37 -04002376 /*
2377 * before we register a new CON_BOOT console, make sure we don't
2378 * already have a valid console
2379 */
2380 if (console_drivers && newcon->flags & CON_BOOT) {
2381 /* find the last or real console */
2382 for_each_console(bcon) {
2383 if (!(bcon->flags & CON_BOOT)) {
Andrew Morton27083ba2013-11-12 15:08:50 -08002384 pr_info("Too late to register bootconsole %s%d\n",
Robin Getz4d091612009-07-01 21:08:37 -04002385 newcon->name, newcon->index);
2386 return;
2387 }
2388 }
Gerd Hoffmann69331af2007-05-08 00:26:49 -07002389 }
2390
Robin Getz4d091612009-07-01 21:08:37 -04002391 if (console_drivers && console_drivers->flags & CON_BOOT)
2392 bcon = console_drivers;
2393
2394 if (preferred_console < 0 || bcon || !console_drivers)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002395 preferred_console = selected_console;
2396
Robin Getz4d091612009-07-01 21:08:37 -04002397 if (newcon->early_setup)
2398 newcon->early_setup();
Yinghai Lu18a8bd92007-07-15 23:37:59 -07002399
Linus Torvalds1da177e2005-04-16 15:20:36 -07002400 /*
2401 * See if we want to use this console driver. If we
2402 * didn't select a console we take the first one
2403 * that registers here.
2404 */
2405 if (preferred_console < 0) {
Robin Getz4d091612009-07-01 21:08:37 -04002406 if (newcon->index < 0)
2407 newcon->index = 0;
2408 if (newcon->setup == NULL ||
2409 newcon->setup(newcon, NULL) == 0) {
2410 newcon->flags |= CON_ENABLED;
2411 if (newcon->device) {
2412 newcon->flags |= CON_CONSDEV;
Jan Kiszkacd3a1b82008-05-12 21:21:04 +02002413 preferred_console = 0;
2414 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002415 }
2416 }
2417
2418 /*
2419 * See if this console matches one we selected on
2420 * the command line.
2421 */
Joe Perches23475402013-07-31 13:53:46 -07002422 for (i = 0, c = console_cmdline;
2423 i < MAX_CMDLINECONSOLES && c->name[0];
2424 i++, c++) {
2425 if (strcmp(c->name, newcon->name) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426 continue;
Robin Getz4d091612009-07-01 21:08:37 -04002427 if (newcon->index >= 0 &&
Joe Perches23475402013-07-31 13:53:46 -07002428 newcon->index != c->index)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002429 continue;
Robin Getz4d091612009-07-01 21:08:37 -04002430 if (newcon->index < 0)
Joe Perches23475402013-07-31 13:53:46 -07002431 newcon->index = c->index;
Joe Perchesbbeddf52013-07-31 13:53:45 -07002432
Joe Perches23475402013-07-31 13:53:46 -07002433 if (_braille_register_console(newcon, c))
Samuel Thibaultf7511d52008-04-30 00:54:51 -07002434 return;
Joe Perchesbbeddf52013-07-31 13:53:45 -07002435
Robin Getz4d091612009-07-01 21:08:37 -04002436 if (newcon->setup &&
2437 newcon->setup(newcon, console_cmdline[i].options) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002438 break;
Robin Getz4d091612009-07-01 21:08:37 -04002439 newcon->flags |= CON_ENABLED;
Joe Perches23475402013-07-31 13:53:46 -07002440 newcon->index = c->index;
Greg Edwardsab4af032005-06-23 00:09:05 -07002441 if (i == selected_console) {
Robin Getz4d091612009-07-01 21:08:37 -04002442 newcon->flags |= CON_CONSDEV;
Greg Edwardsab4af032005-06-23 00:09:05 -07002443 preferred_console = selected_console;
2444 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002445 break;
2446 }
2447
Robin Getz4d091612009-07-01 21:08:37 -04002448 if (!(newcon->flags & CON_ENABLED))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002449 return;
2450
Robin Getz8259cf42009-07-09 13:08:37 -04002451 /*
2452 * If we have a bootconsole, and are switching to a real console,
2453 * don't print everything out again, since when the boot console, and
2454 * the real console are the same physical device, it's annoying to
2455 * see the beginning boot messages twice
2456 */
2457 if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
Robin Getz4d091612009-07-01 21:08:37 -04002458 newcon->flags &= ~CON_PRINTBUFFER;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002459
2460 /*
2461 * Put this console in the list - keep the
2462 * preferred driver at the head of the list.
2463 */
Torben Hohnac751ef2011-01-25 15:07:35 -08002464 console_lock();
Robin Getz4d091612009-07-01 21:08:37 -04002465 if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
2466 newcon->next = console_drivers;
2467 console_drivers = newcon;
2468 if (newcon->next)
2469 newcon->next->flags &= ~CON_CONSDEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002470 } else {
Robin Getz4d091612009-07-01 21:08:37 -04002471 newcon->next = console_drivers->next;
2472 console_drivers->next = newcon;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002473 }
Robin Getz4d091612009-07-01 21:08:37 -04002474 if (newcon->flags & CON_PRINTBUFFER) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002475 /*
Torben Hohnac751ef2011-01-25 15:07:35 -08002476 * console_unlock(); will print out the buffered messages
Linus Torvalds1da177e2005-04-16 15:20:36 -07002477 * for us.
2478 */
Thomas Gleixner07354eb2009-07-25 17:50:36 +02002479 raw_spin_lock_irqsave(&logbuf_lock, flags);
Kay Sievers7ff95542012-05-03 02:29:13 +02002480 console_seq = syslog_seq;
2481 console_idx = syslog_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07002482 console_prev = syslog_prev;
Thomas Gleixner07354eb2009-07-25 17:50:36 +02002483 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
Feng Tangfe3d8ad2011-03-22 16:34:21 -07002484 /*
2485 * We're about to replay the log buffer. Only do this to the
2486 * just-registered console to avoid excessive message spam to
2487 * the already-registered consoles.
2488 */
2489 exclusive_console = newcon;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002490 }
Torben Hohnac751ef2011-01-25 15:07:35 -08002491 console_unlock();
Kay Sieversfbc92a32010-12-01 18:51:05 +01002492 console_sysfs_notify();
Robin Getz8259cf42009-07-09 13:08:37 -04002493
2494 /*
2495 * By unregistering the bootconsoles after we enable the real console
2496 * we get the "console xxx enabled" message on all the consoles -
2497 * boot consoles, real consoles, etc - this is to ensure that end
2498 * users know there might be something in the kernel's log buffer that
2499 * went to the bootconsole (that they do not see on the real console)
2500 */
Andrew Morton27083ba2013-11-12 15:08:50 -08002501 pr_info("%sconsole [%s%d] enabled\n",
Kees Cook6b802392013-11-12 15:08:49 -08002502 (newcon->flags & CON_BOOT) ? "boot" : "" ,
2503 newcon->name, newcon->index);
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -07002504 if (bcon &&
2505 ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
2506 !keep_bootcon) {
Kees Cook6b802392013-11-12 15:08:49 -08002507 /* We need to iterate through all boot consoles, to make
2508 * sure we print everything out, before we unregister them.
Robin Getz8259cf42009-07-09 13:08:37 -04002509 */
Robin Getz8259cf42009-07-09 13:08:37 -04002510 for_each_console(bcon)
2511 if (bcon->flags & CON_BOOT)
2512 unregister_console(bcon);
Robin Getz8259cf42009-07-09 13:08:37 -04002513 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002514}
2515EXPORT_SYMBOL(register_console);
2516
Jesper Juhl40dc5652005-10-30 15:02:46 -08002517int unregister_console(struct console *console)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002518{
Jesper Juhl40dc5652005-10-30 15:02:46 -08002519 struct console *a, *b;
Joe Perchesbbeddf52013-07-31 13:53:45 -07002520 int res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002521
Andrew Morton27083ba2013-11-12 15:08:50 -08002522 pr_info("%sconsole [%s%d] disabled\n",
Kees Cook6b802392013-11-12 15:08:49 -08002523 (console->flags & CON_BOOT) ? "boot" : "" ,
2524 console->name, console->index);
2525
Joe Perchesbbeddf52013-07-31 13:53:45 -07002526 res = _braille_unregister_console(console);
2527 if (res)
2528 return res;
Samuel Thibaultf7511d52008-04-30 00:54:51 -07002529
Joe Perchesbbeddf52013-07-31 13:53:45 -07002530 res = 1;
Torben Hohnac751ef2011-01-25 15:07:35 -08002531 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002532 if (console_drivers == console) {
2533 console_drivers=console->next;
2534 res = 0;
Benjamin Herrenschmidte9b15b52005-11-23 13:37:44 -08002535 } else if (console_drivers) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002536 for (a=console_drivers->next, b=console_drivers ;
2537 a; b=a, a=b->next) {
2538 if (a == console) {
2539 b->next = a->next;
2540 res = 0;
2541 break;
Jesper Juhl40dc5652005-10-30 15:02:46 -08002542 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002543 }
2544 }
Jesper Juhl40dc5652005-10-30 15:02:46 -08002545
Gerd Hoffmann69331af2007-05-08 00:26:49 -07002546 /*
Greg Edwardsab4af032005-06-23 00:09:05 -07002547 * If this isn't the last console and it has CON_CONSDEV set, we
2548 * need to set it on the next preferred console.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002549 */
Gerd Hoffmann69331af2007-05-08 00:26:49 -07002550 if (console_drivers != NULL && console->flags & CON_CONSDEV)
Greg Edwardsab4af032005-06-23 00:09:05 -07002551 console_drivers->flags |= CON_CONSDEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002552
Stephen Chivers7fa21dd2014-05-14 08:04:39 +10002553 console->flags &= ~CON_ENABLED;
Torben Hohnac751ef2011-01-25 15:07:35 -08002554 console_unlock();
Kay Sieversfbc92a32010-12-01 18:51:05 +01002555 console_sysfs_notify();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002556 return res;
2557}
2558EXPORT_SYMBOL(unregister_console);
Matt Mackalld59745c2005-05-01 08:59:02 -07002559
Kevin Cernekee034260d2010-06-03 22:11:25 -07002560static int __init printk_late_init(void)
Robin Getz0c5564b2007-08-20 15:22:47 -04002561{
Robin Getz4d091612009-07-01 21:08:37 -04002562 struct console *con;
2563
2564 for_each_console(con) {
Nishanth Aravamudan4c30c6f2011-08-25 15:59:11 -07002565 if (!keep_bootcon && con->flags & CON_BOOT) {
Sonic Zhang42c2c8c2009-08-06 15:58:11 -07002566 unregister_console(con);
Robin Getzcb00e992007-08-21 23:14:58 -04002567 }
Robin Getz0c5564b2007-08-20 15:22:47 -04002568 }
Kevin Cernekee034260d2010-06-03 22:11:25 -07002569 hotcpu_notifier(console_cpu_notify, 0);
Robin Getz0c5564b2007-08-20 15:22:47 -04002570 return 0;
2571}
Kevin Cernekee034260d2010-06-03 22:11:25 -07002572late_initcall(printk_late_init);
Robin Getz0c5564b2007-08-20 15:22:47 -04002573
Joe Perches7ef3d2f2008-02-08 04:21:25 -08002574#if defined CONFIG_PRINTK
Frederic Weisbeckerdc72c322013-03-22 15:04:39 -07002575/*
2576 * Delayed printk version, for scheduler-internal messages:
2577 */
Frederic Weisbeckerdc72c322013-03-22 15:04:39 -07002578#define PRINTK_PENDING_WAKEUP 0x01
Steven Rostedt458df9f2014-06-04 16:11:38 -07002579#define PRINTK_PENDING_OUTPUT 0x02
Frederic Weisbeckerdc72c322013-03-22 15:04:39 -07002580
2581static DEFINE_PER_CPU(int, printk_pending);
Frederic Weisbeckerdc72c322013-03-22 15:04:39 -07002582
2583static void wake_up_klogd_work_func(struct irq_work *irq_work)
2584{
2585 int pending = __this_cpu_xchg(printk_pending, 0);
2586
Steven Rostedt458df9f2014-06-04 16:11:38 -07002587 if (pending & PRINTK_PENDING_OUTPUT) {
2588 /* If trylock fails, someone else is doing the printing */
2589 if (console_trylock())
2590 console_unlock();
Frederic Weisbeckerdc72c322013-03-22 15:04:39 -07002591 }
2592
2593 if (pending & PRINTK_PENDING_WAKEUP)
2594 wake_up_interruptible(&log_wait);
2595}
2596
2597static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
2598 .func = wake_up_klogd_work_func,
2599 .flags = IRQ_WORK_LAZY,
2600};
2601
2602void wake_up_klogd(void)
2603{
2604 preempt_disable();
2605 if (waitqueue_active(&log_wait)) {
2606 this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
2607 irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
2608 }
2609 preempt_enable();
2610}
Dave Young717115e2008-07-25 01:45:58 -07002611
John Stultzaac74dc2014-06-04 16:11:40 -07002612int printk_deferred(const char *fmt, ...)
Peter Zijlstra600e1452012-03-15 12:35:37 +01002613{
Peter Zijlstra600e1452012-03-15 12:35:37 +01002614 va_list args;
Peter Zijlstra600e1452012-03-15 12:35:37 +01002615 int r;
2616
John Stultz81954602014-06-04 16:11:39 -07002617 preempt_disable();
Peter Zijlstra600e1452012-03-15 12:35:37 +01002618 va_start(args, fmt);
Steven Rostedt458df9f2014-06-04 16:11:38 -07002619 r = vprintk_emit(0, SCHED_MESSAGE_LOGLEVEL, NULL, 0, fmt, args);
Peter Zijlstra600e1452012-03-15 12:35:37 +01002620 va_end(args);
2621
Steven Rostedt458df9f2014-06-04 16:11:38 -07002622 __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
Frederic Weisbecker74876a92012-10-12 18:00:23 +02002623 irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
John Stultz81954602014-06-04 16:11:39 -07002624 preempt_enable();
Peter Zijlstra600e1452012-03-15 12:35:37 +01002625
2626 return r;
2627}
2628
Linus Torvalds1da177e2005-04-16 15:20:36 -07002629/*
2630 * printk rate limiting, lifted from the networking subsystem.
2631 *
Uwe Kleine-König641de9d2008-07-29 22:33:38 -07002632 * This enforces a rate limit: not more than 10 kernel messages
2633 * every 5s to make a denial-of-service attack impossible.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002634 */
Uwe Kleine-König641de9d2008-07-29 22:33:38 -07002635DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
2636
Christian Borntraeger5c828712009-10-23 14:58:11 +02002637int __printk_ratelimit(const char *func)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002638{
Christian Borntraeger5c828712009-10-23 14:58:11 +02002639 return ___ratelimit(&printk_ratelimit_state, func);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002640}
Christian Borntraeger5c828712009-10-23 14:58:11 +02002641EXPORT_SYMBOL(__printk_ratelimit);
Andrew Mortonf46c4832006-11-02 22:07:16 -08002642
2643/**
2644 * printk_timed_ratelimit - caller-controlled printk ratelimiting
2645 * @caller_jiffies: pointer to caller's state
2646 * @interval_msecs: minimum interval between prints
2647 *
2648 * printk_timed_ratelimit() returns true if more than @interval_msecs
2649 * milliseconds have elapsed since the last time printk_timed_ratelimit()
2650 * returned true.
2651 */
2652bool printk_timed_ratelimit(unsigned long *caller_jiffies,
2653 unsigned int interval_msecs)
2654{
Guillaume Knispelf2d28a22009-03-17 16:18:42 +01002655 if (*caller_jiffies == 0
2656 || !time_in_range(jiffies, *caller_jiffies,
2657 *caller_jiffies
2658 + msecs_to_jiffies(interval_msecs))) {
2659 *caller_jiffies = jiffies;
Andrew Mortonf46c4832006-11-02 22:07:16 -08002660 return true;
2661 }
2662 return false;
2663}
2664EXPORT_SYMBOL(printk_timed_ratelimit);
Simon Kagstrom456b5652009-10-16 14:09:18 +02002665
2666static DEFINE_SPINLOCK(dump_list_lock);
2667static LIST_HEAD(dump_list);
2668
2669/**
2670 * kmsg_dump_register - register a kernel log dumper.
Randy Dunlap64855362009-12-17 15:27:27 -08002671 * @dumper: pointer to the kmsg_dumper structure
Simon Kagstrom456b5652009-10-16 14:09:18 +02002672 *
2673 * Adds a kernel log dumper to the system. The dump callback in the
2674 * structure will be called when the kernel oopses or panics and must be
2675 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
2676 */
2677int kmsg_dump_register(struct kmsg_dumper *dumper)
2678{
2679 unsigned long flags;
2680 int err = -EBUSY;
2681
2682 /* The dump callback needs to be set */
2683 if (!dumper->dump)
2684 return -EINVAL;
2685
2686 spin_lock_irqsave(&dump_list_lock, flags);
2687 /* Don't allow registering multiple times */
2688 if (!dumper->registered) {
2689 dumper->registered = 1;
Huang Yingfb842b02011-01-12 16:59:43 -08002690 list_add_tail_rcu(&dumper->list, &dump_list);
Simon Kagstrom456b5652009-10-16 14:09:18 +02002691 err = 0;
2692 }
2693 spin_unlock_irqrestore(&dump_list_lock, flags);
2694
2695 return err;
2696}
2697EXPORT_SYMBOL_GPL(kmsg_dump_register);
2698
2699/**
2700 * kmsg_dump_unregister - unregister a kmsg dumper.
Randy Dunlap64855362009-12-17 15:27:27 -08002701 * @dumper: pointer to the kmsg_dumper structure
Simon Kagstrom456b5652009-10-16 14:09:18 +02002702 *
2703 * Removes a dump device from the system. Returns zero on success and
2704 * %-EINVAL otherwise.
2705 */
2706int kmsg_dump_unregister(struct kmsg_dumper *dumper)
2707{
2708 unsigned long flags;
2709 int err = -EINVAL;
2710
2711 spin_lock_irqsave(&dump_list_lock, flags);
2712 if (dumper->registered) {
2713 dumper->registered = 0;
Huang Yingfb842b02011-01-12 16:59:43 -08002714 list_del_rcu(&dumper->list);
Simon Kagstrom456b5652009-10-16 14:09:18 +02002715 err = 0;
2716 }
2717 spin_unlock_irqrestore(&dump_list_lock, flags);
Huang Yingfb842b02011-01-12 16:59:43 -08002718 synchronize_rcu();
Simon Kagstrom456b5652009-10-16 14:09:18 +02002719
2720 return err;
2721}
2722EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
2723
Kay Sievers7ff95542012-05-03 02:29:13 +02002724static bool always_kmsg_dump;
2725module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
2726
Simon Kagstrom456b5652009-10-16 14:09:18 +02002727/**
2728 * kmsg_dump - dump kernel log to kernel message dumpers.
2729 * @reason: the reason (oops, panic etc) for dumping
2730 *
Kay Sieverse2ae7152012-06-15 14:07:51 +02002731 * Call each of the registered dumper's dump() callback, which can
2732 * retrieve the kmsg records with kmsg_dump_get_line() or
2733 * kmsg_dump_get_buffer().
Simon Kagstrom456b5652009-10-16 14:09:18 +02002734 */
2735void kmsg_dump(enum kmsg_dump_reason reason)
2736{
Simon Kagstrom456b5652009-10-16 14:09:18 +02002737 struct kmsg_dumper *dumper;
Simon Kagstrom456b5652009-10-16 14:09:18 +02002738 unsigned long flags;
2739
Matthew Garrettc22ab332012-03-05 14:59:10 -08002740 if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
2741 return;
2742
Huang Yingfb842b02011-01-12 16:59:43 -08002743 rcu_read_lock();
Kay Sieverse2ae7152012-06-15 14:07:51 +02002744 list_for_each_entry_rcu(dumper, &dump_list, list) {
2745 if (dumper->max_reason && reason > dumper->max_reason)
2746 continue;
2747
2748 /* initialize iterator with data about the stored records */
2749 dumper->active = true;
2750
2751 raw_spin_lock_irqsave(&logbuf_lock, flags);
2752 dumper->cur_seq = clear_seq;
2753 dumper->cur_idx = clear_idx;
2754 dumper->next_seq = log_next_seq;
2755 dumper->next_idx = log_next_idx;
2756 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2757
2758 /* invoke dumper which will iterate over records */
2759 dumper->dump(dumper, reason);
2760
2761 /* reset iterator */
2762 dumper->active = false;
2763 }
Huang Yingfb842b02011-01-12 16:59:43 -08002764 rcu_read_unlock();
Simon Kagstrom456b5652009-10-16 14:09:18 +02002765}
Kay Sieverse2ae7152012-06-15 14:07:51 +02002766
2767/**
Anton Vorontsov533827c2012-07-20 17:28:07 -07002768 * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
2769 * @dumper: registered kmsg dumper
2770 * @syslog: include the "<4>" prefixes
2771 * @line: buffer to copy the line to
2772 * @size: maximum size of the buffer
2773 * @len: length of line placed into buffer
2774 *
2775 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2776 * record, and copy one record into the provided buffer.
2777 *
2778 * Consecutive calls will return the next available record moving
2779 * towards the end of the buffer with the youngest messages.
2780 *
2781 * A return value of FALSE indicates that there are no more records to
2782 * read.
2783 *
2784 * The function is similar to kmsg_dump_get_line(), but grabs no locks.
2785 */
2786bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
2787 char *line, size_t size, size_t *len)
2788{
Joe Perches62e32ac2013-07-31 13:53:47 -07002789 struct printk_log *msg;
Anton Vorontsov533827c2012-07-20 17:28:07 -07002790 size_t l = 0;
2791 bool ret = false;
2792
2793 if (!dumper->active)
2794 goto out;
2795
2796 if (dumper->cur_seq < log_first_seq) {
2797 /* messages are gone, move to first available one */
2798 dumper->cur_seq = log_first_seq;
2799 dumper->cur_idx = log_first_idx;
2800 }
2801
2802 /* last entry */
2803 if (dumper->cur_seq >= log_next_seq)
2804 goto out;
2805
2806 msg = log_from_idx(dumper->cur_idx);
2807 l = msg_print_text(msg, 0, syslog, line, size);
2808
2809 dumper->cur_idx = log_next(dumper->cur_idx);
2810 dumper->cur_seq++;
2811 ret = true;
2812out:
2813 if (len)
2814 *len = l;
2815 return ret;
2816}
2817
2818/**
Kay Sieverse2ae7152012-06-15 14:07:51 +02002819 * kmsg_dump_get_line - retrieve one kmsg log line
2820 * @dumper: registered kmsg dumper
2821 * @syslog: include the "<4>" prefixes
2822 * @line: buffer to copy the line to
2823 * @size: maximum size of the buffer
2824 * @len: length of line placed into buffer
2825 *
2826 * Start at the beginning of the kmsg buffer, with the oldest kmsg
2827 * record, and copy one record into the provided buffer.
2828 *
2829 * Consecutive calls will return the next available record moving
2830 * towards the end of the buffer with the youngest messages.
2831 *
2832 * A return value of FALSE indicates that there are no more records to
2833 * read.
2834 */
2835bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
2836 char *line, size_t size, size_t *len)
2837{
2838 unsigned long flags;
Anton Vorontsov533827c2012-07-20 17:28:07 -07002839 bool ret;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002840
2841 raw_spin_lock_irqsave(&logbuf_lock, flags);
Anton Vorontsov533827c2012-07-20 17:28:07 -07002842 ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002843 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
Anton Vorontsov533827c2012-07-20 17:28:07 -07002844
Kay Sieverse2ae7152012-06-15 14:07:51 +02002845 return ret;
2846}
2847EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
2848
2849/**
2850 * kmsg_dump_get_buffer - copy kmsg log lines
2851 * @dumper: registered kmsg dumper
2852 * @syslog: include the "<4>" prefixes
Randy Dunlap4f0f4af2012-06-30 15:37:24 -07002853 * @buf: buffer to copy the line to
Kay Sieverse2ae7152012-06-15 14:07:51 +02002854 * @size: maximum size of the buffer
2855 * @len: length of line placed into buffer
2856 *
2857 * Start at the end of the kmsg buffer and fill the provided buffer
2858 * with as many of the the *youngest* kmsg records that fit into it.
2859 * If the buffer is large enough, all available kmsg records will be
2860 * copied with a single call.
2861 *
2862 * Consecutive calls will fill the buffer with the next block of
2863 * available older records, not including the earlier retrieved ones.
2864 *
2865 * A return value of FALSE indicates that there are no more records to
2866 * read.
2867 */
2868bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
2869 char *buf, size_t size, size_t *len)
2870{
2871 unsigned long flags;
2872 u64 seq;
2873 u32 idx;
2874 u64 next_seq;
2875 u32 next_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07002876 enum log_flags prev;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002877 size_t l = 0;
2878 bool ret = false;
2879
2880 if (!dumper->active)
2881 goto out;
2882
2883 raw_spin_lock_irqsave(&logbuf_lock, flags);
2884 if (dumper->cur_seq < log_first_seq) {
2885 /* messages are gone, move to first available one */
2886 dumper->cur_seq = log_first_seq;
2887 dumper->cur_idx = log_first_idx;
2888 }
2889
2890 /* last entry */
2891 if (dumper->cur_seq >= dumper->next_seq) {
2892 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2893 goto out;
2894 }
2895
2896 /* calculate length of entire buffer */
2897 seq = dumper->cur_seq;
2898 idx = dumper->cur_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07002899 prev = 0;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002900 while (seq < dumper->next_seq) {
Joe Perches62e32ac2013-07-31 13:53:47 -07002901 struct printk_log *msg = log_from_idx(idx);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002902
Kay Sievers5becfb12012-07-09 12:15:42 -07002903 l += msg_print_text(msg, prev, true, NULL, 0);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002904 idx = log_next(idx);
2905 seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07002906 prev = msg->flags;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002907 }
2908
2909 /* move first record forward until length fits into the buffer */
2910 seq = dumper->cur_seq;
2911 idx = dumper->cur_idx;
Kay Sievers5becfb12012-07-09 12:15:42 -07002912 prev = 0;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002913 while (l > size && seq < dumper->next_seq) {
Joe Perches62e32ac2013-07-31 13:53:47 -07002914 struct printk_log *msg = log_from_idx(idx);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002915
Kay Sievers5becfb12012-07-09 12:15:42 -07002916 l -= msg_print_text(msg, prev, true, NULL, 0);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002917 idx = log_next(idx);
2918 seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07002919 prev = msg->flags;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002920 }
2921
2922 /* last message in next interation */
2923 next_seq = seq;
2924 next_idx = idx;
2925
2926 l = 0;
2927 while (seq < dumper->next_seq) {
Joe Perches62e32ac2013-07-31 13:53:47 -07002928 struct printk_log *msg = log_from_idx(idx);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002929
Kay Sievers5becfb12012-07-09 12:15:42 -07002930 l += msg_print_text(msg, prev, syslog, buf + l, size - l);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002931 idx = log_next(idx);
2932 seq++;
Kay Sievers5becfb12012-07-09 12:15:42 -07002933 prev = msg->flags;
Kay Sieverse2ae7152012-06-15 14:07:51 +02002934 }
2935
2936 dumper->next_seq = next_seq;
2937 dumper->next_idx = next_idx;
2938 ret = true;
2939 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2940out:
2941 if (len)
2942 *len = l;
2943 return ret;
2944}
2945EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
2946
2947/**
Anton Vorontsov533827c2012-07-20 17:28:07 -07002948 * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
2949 * @dumper: registered kmsg dumper
2950 *
2951 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2952 * kmsg_dump_get_buffer() can be called again and used multiple
2953 * times within the same dumper.dump() callback.
2954 *
2955 * The function is similar to kmsg_dump_rewind(), but grabs no locks.
2956 */
2957void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
2958{
2959 dumper->cur_seq = clear_seq;
2960 dumper->cur_idx = clear_idx;
2961 dumper->next_seq = log_next_seq;
2962 dumper->next_idx = log_next_idx;
2963}
2964
2965/**
Kay Sieverse2ae7152012-06-15 14:07:51 +02002966 * kmsg_dump_rewind - reset the interator
2967 * @dumper: registered kmsg dumper
2968 *
2969 * Reset the dumper's iterator so that kmsg_dump_get_line() and
2970 * kmsg_dump_get_buffer() can be called again and used multiple
2971 * times within the same dumper.dump() callback.
2972 */
2973void kmsg_dump_rewind(struct kmsg_dumper *dumper)
2974{
2975 unsigned long flags;
2976
2977 raw_spin_lock_irqsave(&logbuf_lock, flags);
Anton Vorontsov533827c2012-07-20 17:28:07 -07002978 kmsg_dump_rewind_nolock(dumper);
Kay Sieverse2ae7152012-06-15 14:07:51 +02002979 raw_spin_unlock_irqrestore(&logbuf_lock, flags);
2980}
2981EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
Tejun Heo196779b2013-04-30 15:27:12 -07002982
Tejun Heo98e5e1b2013-04-30 15:27:15 -07002983static char dump_stack_arch_desc_str[128];
2984
2985/**
2986 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
2987 * @fmt: printf-style format string
2988 * @...: arguments for the format string
2989 *
2990 * The configured string will be printed right after utsname during task
2991 * dumps. Usually used to add arch-specific system identifiers. If an
2992 * arch wants to make use of such an ID string, it should initialize this
2993 * as soon as possible during boot.
2994 */
2995void __init dump_stack_set_arch_desc(const char *fmt, ...)
2996{
2997 va_list args;
2998
2999 va_start(args, fmt);
3000 vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
3001 fmt, args);
3002 va_end(args);
3003}
3004
Tejun Heo196779b2013-04-30 15:27:12 -07003005/**
3006 * dump_stack_print_info - print generic debug info for dump_stack()
3007 * @log_lvl: log level
3008 *
3009 * Arch-specific dump_stack() implementations can use this function to
3010 * print out the same debug information as the generic dump_stack().
3011 */
3012void dump_stack_print_info(const char *log_lvl)
3013{
3014 printk("%sCPU: %d PID: %d Comm: %.20s %s %s %.*s\n",
3015 log_lvl, raw_smp_processor_id(), current->pid, current->comm,
3016 print_tainted(), init_utsname()->release,
3017 (int)strcspn(init_utsname()->version, " "),
3018 init_utsname()->version);
Tejun Heo98e5e1b2013-04-30 15:27:15 -07003019
3020 if (dump_stack_arch_desc_str[0] != '\0')
3021 printk("%sHardware name: %s\n",
3022 log_lvl, dump_stack_arch_desc_str);
Tejun Heo3d1cb202013-04-30 15:27:22 -07003023
3024 print_worker_info(log_lvl, current);
Tejun Heo196779b2013-04-30 15:27:12 -07003025}
3026
Tejun Heoa43cb952013-04-30 15:27:17 -07003027/**
3028 * show_regs_print_info - print generic debug info for show_regs()
3029 * @log_lvl: log level
3030 *
3031 * show_regs() implementations can use this function to print out generic
3032 * debug information.
3033 */
3034void show_regs_print_info(const char *log_lvl)
3035{
3036 dump_stack_print_info(log_lvl);
3037
3038 printk("%stask: %p ti: %p task.ti: %p\n",
3039 log_lvl, current, current_thread_info(),
3040 task_thread_info(current));
3041}
3042
Joe Perches7ef3d2f2008-02-08 04:21:25 -08003043#endif