blob: 3c3139577992aeaec2fecb031b0dad05cc5b7da9 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/kernel/printk.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * Modified to make sys_syslog() more flexible: added commands to
7 * return the last 4k of kernel messages, regardless of whether
8 * they've been read or not. Added option to suppress kernel printk's
9 * to the console. Added hook for sending the console messages
10 * elsewhere, in preparation for a serial line console (someday).
11 * Ted Ts'o, 2/11/93.
12 * Modified for sysctl support, 1/8/97, Chris Horn.
Jesper Juhl40dc5652005-10-30 15:02:46 -080013 * Fixed SMP synchronization, 08/08/99, Manfred Spraul
Christian Kujau624dffc2006-01-15 02:43:54 +010014 * manfred@colorfullife.com
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 * Rewrote bits to get rid of console_lock
Francois Camie1f8e872008-10-15 22:01:59 -070016 * 01Mar01 Andrew Morton
Linus Torvalds1da177e2005-04-16 15:20:36 -070017 */
18
19#include <linux/kernel.h>
20#include <linux/mm.h>
21#include <linux/tty.h>
22#include <linux/tty_driver.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <linux/console.h>
24#include <linux/init.h>
Randy Dunlapbfe8df32007-10-16 01:23:46 -070025#include <linux/jiffies.h>
26#include <linux/nmi.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/module.h>
Jan Engelhardt3b9c0412006-06-25 05:48:15 -070028#include <linux/moduleparam.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/interrupt.h> /* For in_interrupt() */
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include <linux/delay.h>
31#include <linux/smp.h>
32#include <linux/security.h>
33#include <linux/bootmem.h>
Mike Travis162a7e72011-05-24 17:13:20 -070034#include <linux/memblock.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <linux/syscalls.h>
Neil Horman04d491a2009-04-02 16:58:57 -070036#include <linux/kexec.h>
Jason Wesseld37d39a2010-05-20 21:04:27 -050037#include <linux/kdb.h>
Ingo Molnar3fff4c42009-09-22 16:18:09 +020038#include <linux/ratelimit.h>
Simon Kagstrom456b5652009-10-16 14:09:18 +020039#include <linux/kmsg_dump.h>
Kees Cook00234592010-02-03 15:36:43 -080040#include <linux/syslog.h>
Kevin Cernekee034260d2010-06-03 22:11:25 -070041#include <linux/cpu.h>
42#include <linux/notifier.h>
Huang Yingfb842b02011-01-12 16:59:43 -080043#include <linux/rculist.h>
Laura Abbottaa9b60b2012-01-23 13:06:20 -080044#include <mach/msm_rtb.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045#include <asm/uaccess.h>
46
Ingo Molnar076f9772008-01-30 13:33:06 +010047/*
48 * Architectures can override it:
49 */
Jiri Slabye17ba732008-05-12 15:44:40 +020050void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...)
Ingo Molnar076f9772008-01-30 13:33:06 +010051{
52}
53
Linus Torvalds1da177e2005-04-16 15:20:36 -070054#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
55
56/* printk's without a loglevel use this.. */
Mandeep Singh Baines5af5bcb2011-03-22 16:34:23 -070057#define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
59/* We show everything that is MORE important than this.. */
60#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
61#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
62
63DECLARE_WAIT_QUEUE_HEAD(log_wait);
64
65int console_printk[4] = {
66 DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
67 DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
68 MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */
69 DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
70};
71
Linus Torvalds1da177e2005-04-16 15:20:36 -070072/*
Patrick Pletscher0bbfb7c2007-02-17 20:10:16 +010073 * Low level drivers may need that to know if they can schedule in
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 * their unblank() callback or not. So let's export it.
75 */
76int oops_in_progress;
77EXPORT_SYMBOL(oops_in_progress);
78
79/*
80 * console_sem protects the console_drivers list, and also
81 * provides serialisation for access to the entire console
82 * driver system.
83 */
Thomas Gleixner5b8c4f22010-09-07 14:33:43 +000084static DEFINE_SEMAPHORE(console_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -070085struct console *console_drivers;
Ingo Molnara29d1cf2008-06-02 13:19:08 +020086EXPORT_SYMBOL_GPL(console_drivers);
87
Linus Torvalds1da177e2005-04-16 15:20:36 -070088/*
89 * This is used for debugging the mess that is the VT code by
90 * keeping track if we have the console semaphore held. It's
91 * definitely not the perfect debug tool (we don't know if _WE_
92 * hold it are racing, but it helps tracking those weird code
93 * path in the console code where we end up in places I want
94 * locked without the console sempahore held
95 */
Linus Torvalds557240b2006-06-19 18:16:01 -070096static int console_locked, console_suspended;
Linus Torvalds1da177e2005-04-16 15:20:36 -070097
98/*
99 * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars
100 * It is also used in interesting ways to provide interlocking in
Torben Hohnac751ef2011-01-25 15:07:35 -0800101 * console_unlock();.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 */
103static DEFINE_SPINLOCK(logbuf_lock);
104
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800105#define LOG_BUF_MASK (log_buf_len-1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106#define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK])
107
108/*
109 * The indices into log_buf are not constrained to log_buf_len - they
110 * must be masked before subscripting
111 */
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800112static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */
113static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */
114static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115
116/*
Feng Tangfe3d8ad2011-03-22 16:34:21 -0700117 * If exclusive_console is non-NULL then only this console is to be printed to.
118 */
119static struct console *exclusive_console;
120
121/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 * Array of consoles built from command line options (console=)
123 */
124struct console_cmdline
125{
126 char name[8]; /* Name of the driver */
127 int index; /* Minor dev. to use */
128 char *options; /* Options for the driver */
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700129#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
130 char *brl_options; /* Options for braille driver */
131#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132};
133
134#define MAX_CMDLINECONSOLES 8
135
136static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
137static int selected_console = -1;
138static int preferred_console = -1;
Markus Armbruster9e124fe2008-05-26 23:31:07 +0100139int console_set_on_cmdline;
140EXPORT_SYMBOL(console_set_on_cmdline);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141
142/* Flag: console code may call schedule() */
143static int console_may_schedule;
144
Matt Mackalld59745c2005-05-01 08:59:02 -0700145#ifdef CONFIG_PRINTK
146
147static char __log_buf[__LOG_BUF_LEN];
148static char *log_buf = __log_buf;
149static int log_buf_len = __LOG_BUF_LEN;
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800150static unsigned logged_chars; /* Number of chars produced since last read+clear operation */
Gustavo F. Padovancea83882010-03-05 13:42:58 -0800151static int saved_console_loglevel = -1;
Matt Mackalld59745c2005-05-01 08:59:02 -0700152
Neil Horman04d491a2009-04-02 16:58:57 -0700153#ifdef CONFIG_KEXEC
154/*
155 * This appends the listed symbols to /proc/vmcoreinfo
156 *
157 * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
158 * obtain access to symbols that are otherwise very difficult to locate. These
159 * symbols are specifically used so that utilities can access and extract the
160 * dmesg log from a vmcore file after a crash.
161 */
162void log_buf_kexec_setup(void)
163{
164 VMCOREINFO_SYMBOL(log_buf);
165 VMCOREINFO_SYMBOL(log_end);
166 VMCOREINFO_SYMBOL(log_buf_len);
167 VMCOREINFO_SYMBOL(logged_chars);
168}
169#endif
170
Mike Travis162a7e72011-05-24 17:13:20 -0700171/* requested log_buf_len from kernel cmdline */
172static unsigned long __initdata new_log_buf_len;
173
174/* save requested log_buf_len since it's too early to process it */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175static int __init log_buf_len_setup(char *str)
176{
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800177 unsigned size = memparse(str, &str);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178
179 if (size)
180 size = roundup_pow_of_two(size);
Mike Travis162a7e72011-05-24 17:13:20 -0700181 if (size > log_buf_len)
182 new_log_buf_len = size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183
Mike Travis162a7e72011-05-24 17:13:20 -0700184 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185}
Mike Travis162a7e72011-05-24 17:13:20 -0700186early_param("log_buf_len", log_buf_len_setup);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
Mike Travis162a7e72011-05-24 17:13:20 -0700188void __init setup_log_buf(int early)
189{
190 unsigned long flags;
191 unsigned start, dest_idx, offset;
192 char *new_log_buf;
193 int free;
194
195 if (!new_log_buf_len)
196 return;
197
198 if (early) {
199 unsigned long mem;
200
201 mem = memblock_alloc(new_log_buf_len, PAGE_SIZE);
202 if (mem == MEMBLOCK_ERROR)
203 return;
204 new_log_buf = __va(mem);
205 } else {
206 new_log_buf = alloc_bootmem_nopanic(new_log_buf_len);
207 }
208
209 if (unlikely(!new_log_buf)) {
210 pr_err("log_buf_len: %ld bytes not available\n",
211 new_log_buf_len);
212 return;
213 }
214
215 spin_lock_irqsave(&logbuf_lock, flags);
216 log_buf_len = new_log_buf_len;
217 log_buf = new_log_buf;
218 new_log_buf_len = 0;
219 free = __LOG_BUF_LEN - log_end;
220
221 offset = start = min(con_start, log_start);
222 dest_idx = 0;
223 while (start != log_end) {
224 unsigned log_idx_mask = start & (__LOG_BUF_LEN - 1);
225
226 log_buf[dest_idx] = __log_buf[log_idx_mask];
227 start++;
228 dest_idx++;
229 }
230 log_start -= offset;
231 con_start -= offset;
232 log_end -= offset;
233 spin_unlock_irqrestore(&logbuf_lock, flags);
234
235 pr_info("log_buf_len: %d\n", log_buf_len);
236 pr_info("early log buf free: %d(%d%%)\n",
237 free, (free * 100) / __LOG_BUF_LEN);
238}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700240#ifdef CONFIG_BOOT_PRINTK_DELAY
241
Namhyung Kim674dff62010-10-26 14:22:48 -0700242static int boot_delay; /* msecs delay after each printk during bootup */
Dave Young3a3b6ed2009-09-22 16:43:31 -0700243static unsigned long long loops_per_msec; /* based on boot_delay */
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700244
245static int __init boot_delay_setup(char *str)
246{
247 unsigned long lpj;
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700248
249 lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */
250 loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
251
252 get_option(&str, &boot_delay);
253 if (boot_delay > 10 * 1000)
254 boot_delay = 0;
255
Dave Young3a3b6ed2009-09-22 16:43:31 -0700256 pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
257 "HZ: %d, loops_per_msec: %llu\n",
258 boot_delay, preset_lpj, lpj, HZ, loops_per_msec);
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700259 return 1;
260}
261__setup("boot_delay=", boot_delay_setup);
262
263static void boot_delay_msec(void)
264{
265 unsigned long long k;
266 unsigned long timeout;
267
268 if (boot_delay == 0 || system_state != SYSTEM_BOOTING)
269 return;
270
Dave Young3a3b6ed2009-09-22 16:43:31 -0700271 k = (unsigned long long)loops_per_msec * boot_delay;
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700272
273 timeout = jiffies + msecs_to_jiffies(boot_delay);
274 while (k) {
275 k--;
276 cpu_relax();
277 /*
278 * use (volatile) jiffies to prevent
279 * compiler reduction; loop termination via jiffies
280 * is secondary and may or may not happen.
281 */
282 if (time_after(jiffies, timeout))
283 break;
284 touch_nmi_watchdog();
285 }
286}
287#else
288static inline void boot_delay_msec(void)
289{
290}
291#endif
292
Arve Hjønnevågfc4fb282009-01-15 19:07:27 -0800293/*
294 * Return the number of unread characters in the log buffer.
295 */
296static int log_buf_get_len(void)
297{
298 return logged_chars;
299}
300
301/*
San Mehatce84ca92009-08-06 10:25:21 -0700302 * Clears the ring-buffer
303 */
304void log_buf_clear(void)
305{
306 logged_chars = 0;
307}
308
309/*
Arve Hjønnevågfc4fb282009-01-15 19:07:27 -0800310 * Copy a range of characters from the log buffer.
311 */
312int log_buf_copy(char *dest, int idx, int len)
313{
314 int ret, max;
315 bool took_lock = false;
316
317 if (!oops_in_progress) {
318 spin_lock_irq(&logbuf_lock);
319 took_lock = true;
320 }
321
322 max = log_buf_get_len();
323 if (idx < 0 || idx >= max) {
324 ret = -1;
325 } else {
Arve Hjønnevåg0da19af2008-04-14 21:35:25 -0700326 if (len > max - idx)
327 len = max - idx;
Arve Hjønnevågfc4fb282009-01-15 19:07:27 -0800328 ret = len;
329 idx += (log_end - max);
330 while (len-- > 0)
331 dest[len] = LOG_BUF(idx + len);
332 }
333
334 if (took_lock)
335 spin_unlock_irq(&logbuf_lock);
336
337 return ret;
338}
339
Dan Rosenbergeaf06b22010-11-11 14:05:18 -0800340#ifdef CONFIG_SECURITY_DMESG_RESTRICT
341int dmesg_restrict = 1;
342#else
343int dmesg_restrict;
344#endif
345
Linus Torvaldsee24aeb2011-02-10 17:53:55 -0800346static int syslog_action_restricted(int type)
347{
348 if (dmesg_restrict)
349 return 1;
350 /* Unless restricted, we allow "read all" and "get buffer size" for everybody */
351 return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER;
352}
353
354static int check_syslog_permissions(int type, bool from_file)
355{
356 /*
357 * If this is from /proc/kmsg and we've already opened it, then we've
358 * already done the capabilities checks at open time.
359 */
360 if (from_file && type != SYSLOG_ACTION_OPEN)
361 return 0;
362
363 if (syslog_action_restricted(type)) {
364 if (capable(CAP_SYSLOG))
365 return 0;
366 /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */
367 if (capable(CAP_SYS_ADMIN)) {
368 WARN_ONCE(1, "Attempt to access syslog with CAP_SYS_ADMIN "
369 "but no CAP_SYSLOG (deprecated).\n");
370 return 0;
371 }
372 return -EPERM;
373 }
374 return 0;
375}
376
Kees Cook00234592010-02-03 15:36:43 -0800377int do_syslog(int type, char __user *buf, int len, bool from_file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378{
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800379 unsigned i, j, limit, count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 int do_clear = 0;
381 char c;
Linus Torvaldsee24aeb2011-02-10 17:53:55 -0800382 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383
Linus Torvaldsee24aeb2011-02-10 17:53:55 -0800384 error = check_syslog_permissions(type, from_file);
385 if (error)
386 goto out;
Eric Paris12b30522010-11-15 18:36:29 -0500387
388 error = security_syslog(type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 if (error)
390 return error;
391
392 switch (type) {
Kees Cookd78ca3c2010-02-03 15:37:13 -0800393 case SYSLOG_ACTION_CLOSE: /* Close log */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -0800395 case SYSLOG_ACTION_OPEN: /* Open log */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -0800397 case SYSLOG_ACTION_READ: /* Read from log */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 error = -EINVAL;
399 if (!buf || len < 0)
400 goto out;
401 error = 0;
402 if (!len)
403 goto out;
404 if (!access_ok(VERIFY_WRITE, buf, len)) {
405 error = -EFAULT;
406 goto out;
407 }
Jesper Juhl40dc5652005-10-30 15:02:46 -0800408 error = wait_event_interruptible(log_wait,
409 (log_start - log_end));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 if (error)
411 goto out;
412 i = 0;
413 spin_lock_irq(&logbuf_lock);
414 while (!error && (log_start != log_end) && i < len) {
415 c = LOG_BUF(log_start);
416 log_start++;
417 spin_unlock_irq(&logbuf_lock);
418 error = __put_user(c,buf);
419 buf++;
420 i++;
421 cond_resched();
422 spin_lock_irq(&logbuf_lock);
423 }
424 spin_unlock_irq(&logbuf_lock);
425 if (!error)
426 error = i;
427 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -0800428 /* Read/clear last kernel messages */
429 case SYSLOG_ACTION_READ_CLEAR:
Jesper Juhl40dc5652005-10-30 15:02:46 -0800430 do_clear = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 /* FALL THRU */
Kees Cookd78ca3c2010-02-03 15:37:13 -0800432 /* Read last kernel messages */
433 case SYSLOG_ACTION_READ_ALL:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 error = -EINVAL;
435 if (!buf || len < 0)
436 goto out;
437 error = 0;
438 if (!len)
439 goto out;
440 if (!access_ok(VERIFY_WRITE, buf, len)) {
441 error = -EFAULT;
442 goto out;
443 }
444 count = len;
445 if (count > log_buf_len)
446 count = log_buf_len;
447 spin_lock_irq(&logbuf_lock);
448 if (count > logged_chars)
449 count = logged_chars;
450 if (do_clear)
451 logged_chars = 0;
452 limit = log_end;
453 /*
454 * __put_user() could sleep, and while we sleep
Jesper Juhl40dc5652005-10-30 15:02:46 -0800455 * printk() could overwrite the messages
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 * we try to copy to user space. Therefore
457 * the messages are copied in reverse. <manfreds>
458 */
Jesper Juhl40dc5652005-10-30 15:02:46 -0800459 for (i = 0; i < count && !error; i++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 j = limit-1-i;
461 if (j + log_buf_len < log_end)
462 break;
463 c = LOG_BUF(j);
464 spin_unlock_irq(&logbuf_lock);
465 error = __put_user(c,&buf[count-1-i]);
466 cond_resched();
467 spin_lock_irq(&logbuf_lock);
468 }
469 spin_unlock_irq(&logbuf_lock);
470 if (error)
471 break;
472 error = i;
Jesper Juhl40dc5652005-10-30 15:02:46 -0800473 if (i != count) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 int offset = count-error;
475 /* buffer overflow during copy, correct user buffer. */
Jesper Juhl40dc5652005-10-30 15:02:46 -0800476 for (i = 0; i < error; i++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 if (__get_user(c,&buf[i+offset]) ||
478 __put_user(c,&buf[i])) {
479 error = -EFAULT;
480 break;
481 }
482 cond_resched();
483 }
484 }
485 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -0800486 /* Clear ring buffer */
487 case SYSLOG_ACTION_CLEAR:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 logged_chars = 0;
489 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -0800490 /* Disable logging to console */
491 case SYSLOG_ACTION_CONSOLE_OFF:
Frans Pop1aaad492009-07-06 13:31:48 +0200492 if (saved_console_loglevel == -1)
493 saved_console_loglevel = console_loglevel;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 console_loglevel = minimum_console_loglevel;
495 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -0800496 /* Enable logging to console */
497 case SYSLOG_ACTION_CONSOLE_ON:
Frans Pop1aaad492009-07-06 13:31:48 +0200498 if (saved_console_loglevel != -1) {
499 console_loglevel = saved_console_loglevel;
500 saved_console_loglevel = -1;
501 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -0800503 /* Set level of messages printed to console */
504 case SYSLOG_ACTION_CONSOLE_LEVEL:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505 error = -EINVAL;
506 if (len < 1 || len > 8)
507 goto out;
508 if (len < minimum_console_loglevel)
509 len = minimum_console_loglevel;
510 console_loglevel = len;
Frans Pop1aaad492009-07-06 13:31:48 +0200511 /* Implicitly re-enable logging to console */
512 saved_console_loglevel = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 error = 0;
514 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -0800515 /* Number of chars in the log buffer */
516 case SYSLOG_ACTION_SIZE_UNREAD:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517 error = log_end - log_start;
518 break;
Kees Cookd78ca3c2010-02-03 15:37:13 -0800519 /* Size of the log buffer */
520 case SYSLOG_ACTION_SIZE_BUFFER:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 error = log_buf_len;
522 break;
523 default:
524 error = -EINVAL;
525 break;
526 }
527out:
528 return error;
529}
530
Heiko Carstens1e7bfb22009-01-14 14:14:29 +0100531SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532{
Kees Cook00234592010-02-03 15:36:43 -0800533 return do_syslog(type, buf, len, SYSLOG_FROM_CALL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534}
535
Jason Wessel67fc4e02010-05-20 21:04:21 -0500536#ifdef CONFIG_KGDB_KDB
537/* kdb dmesg command needs access to the syslog buffer. do_syslog()
538 * uses locks so it cannot be used during debugging. Just tell kdb
539 * where the start and end of the physical and logical logs are. This
540 * is equivalent to do_syslog(3).
541 */
542void kdb_syslog_data(char *syslog_data[4])
543{
544 syslog_data[0] = log_buf;
545 syslog_data[1] = log_buf + log_buf_len;
546 syslog_data[2] = log_buf + log_end -
547 (logged_chars < log_buf_len ? logged_chars : log_buf_len);
548 syslog_data[3] = log_buf + log_end;
549}
550#endif /* CONFIG_KGDB_KDB */
551
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552/*
553 * Call the console drivers on a range of log_buf
554 */
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800555static void __call_console_drivers(unsigned start, unsigned end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556{
557 struct console *con;
558
Robin Getz4d091612009-07-01 21:08:37 -0400559 for_each_console(con) {
Feng Tangfe3d8ad2011-03-22 16:34:21 -0700560 if (exclusive_console && con != exclusive_console)
561 continue;
Michael Ellerman76a8ad22006-06-25 05:47:40 -0700562 if ((con->flags & CON_ENABLED) && con->write &&
563 (cpu_online(smp_processor_id()) ||
564 (con->flags & CON_ANYTIME)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565 con->write(con, &LOG_BUF(start), end - start);
566 }
567}
568
Ingo Molnar792908222006-12-06 20:40:51 -0800569static int __read_mostly ignore_loglevel;
570
Adrian Bunk99eea6a2006-12-22 01:07:00 -0800571static int __init ignore_loglevel_setup(char *str)
Ingo Molnar792908222006-12-06 20:40:51 -0800572{
573 ignore_loglevel = 1;
574 printk(KERN_INFO "debug: ignoring loglevel setting.\n");
575
Ingo Molnarc4772d92008-01-31 22:45:23 +0100576 return 0;
Ingo Molnar792908222006-12-06 20:40:51 -0800577}
578
Ingo Molnarc4772d92008-01-31 22:45:23 +0100579early_param("ignore_loglevel", ignore_loglevel_setup);
Ingo Molnar792908222006-12-06 20:40:51 -0800580
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581/*
582 * Write out chars from start to end - 1 inclusive
583 */
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800584static void _call_console_drivers(unsigned start,
585 unsigned end, int msg_log_level)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586{
Ingo Molnar792908222006-12-06 20:40:51 -0800587 if ((msg_log_level < console_loglevel || ignore_loglevel) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588 console_drivers && start != end) {
589 if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) {
590 /* wrapped write */
591 __call_console_drivers(start & LOG_BUF_MASK,
592 log_buf_len);
593 __call_console_drivers(0, end & LOG_BUF_MASK);
594 } else {
595 __call_console_drivers(start, end);
596 }
597 }
598}
599
600/*
Kay Sievers9d90c8d2011-03-13 03:19:51 +0100601 * Parse the syslog header <[0-9]*>. The decimal value represents 32bit, the
602 * lower 3 bit are the log level, the rest are the log facility. In case
603 * userspace passes usual userspace syslog messages to /dev/kmsg or
604 * /dev/ttyprintk, the log prefix might contain the facility. Printk needs
605 * to extract the correct log level for in-kernel processing, and not mangle
606 * the original value.
607 *
608 * If a prefix is found, the length of the prefix is returned. If 'level' is
609 * passed, it will be filled in with the log level without a possible facility
610 * value. If 'special' is passed, the special printk prefix chars are accepted
611 * and returned. If no valid header is found, 0 is returned and the passed
612 * variables are not touched.
613 */
614static size_t log_prefix(const char *p, unsigned int *level, char *special)
615{
616 unsigned int lev = 0;
617 char sp = '\0';
618 size_t len;
619
620 if (p[0] != '<' || !p[1])
621 return 0;
622 if (p[2] == '>') {
623 /* usual single digit level number or special char */
624 switch (p[1]) {
625 case '0' ... '7':
626 lev = p[1] - '0';
627 break;
628 case 'c': /* KERN_CONT */
629 case 'd': /* KERN_DEFAULT */
630 sp = p[1];
631 break;
632 default:
633 return 0;
634 }
635 len = 3;
636 } else {
637 /* multi digit including the level and facility number */
638 char *endp = NULL;
639
640 if (p[1] < '0' && p[1] > '9')
641 return 0;
642
643 lev = (simple_strtoul(&p[1], &endp, 10) & 7);
644 if (endp == NULL || endp[0] != '>')
645 return 0;
646 len = (endp + 1) - p;
647 }
648
649 /* do not accept special char if not asked for */
650 if (sp && !special)
651 return 0;
652
653 if (special) {
654 *special = sp;
655 /* return special char, do not touch level */
656 if (sp)
657 return len;
658 }
659
660 if (level)
661 *level = lev;
662 return len;
663}
664
665/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 * Call the console drivers, asking them to write out
667 * log_buf[start] to log_buf[end - 1].
Torben Hohnac751ef2011-01-25 15:07:35 -0800668 * The console_lock must be held.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 */
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800670static void call_console_drivers(unsigned start, unsigned end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671{
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800672 unsigned cur_index, start_print;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 static int msg_level = -1;
674
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -0800675 BUG_ON(((int)(start - end)) > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676
677 cur_index = start;
678 start_print = start;
679 while (cur_index != end) {
Kay Sievers9d90c8d2011-03-13 03:19:51 +0100680 if (msg_level < 0 && ((end - cur_index) > 2)) {
681 /* strip log prefix */
682 cur_index += log_prefix(&LOG_BUF(cur_index), &msg_level, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 start_print = cur_index;
684 }
685 while (cur_index != end) {
686 char c = LOG_BUF(cur_index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687
Jesper Juhl40dc5652005-10-30 15:02:46 -0800688 cur_index++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689 if (c == '\n') {
690 if (msg_level < 0) {
691 /*
692 * printk() has already given us loglevel tags in
693 * the buffer. This code is here in case the
694 * log buffer has wrapped right round and scribbled
695 * on those tags
696 */
697 msg_level = default_message_loglevel;
698 }
699 _call_console_drivers(start_print, cur_index, msg_level);
700 msg_level = -1;
701 start_print = cur_index;
702 break;
703 }
704 }
705 }
706 _call_console_drivers(start_print, end, msg_level);
707}
708
709static void emit_log_char(char c)
710{
711 LOG_BUF(log_end) = c;
712 log_end++;
713 if (log_end - log_start > log_buf_len)
714 log_start = log_end - log_buf_len;
715 if (log_end - con_start > log_buf_len)
716 con_start = log_end - log_buf_len;
717 if (logged_chars < log_buf_len)
718 logged_chars++;
719}
720
721/*
722 * Zap console related locks when oopsing. Only zap at most once
723 * every 10 seconds, to leave time for slow consoles to print a
724 * full oops.
725 */
726static void zap_locks(void)
727{
728 static unsigned long oops_timestamp;
729
730 if (time_after_eq(jiffies, oops_timestamp) &&
Jesper Juhl40dc5652005-10-30 15:02:46 -0800731 !time_after(jiffies, oops_timestamp + 30 * HZ))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732 return;
733
734 oops_timestamp = jiffies;
735
736 /* If a crash is occurring, make sure we can't deadlock */
737 spin_lock_init(&logbuf_lock);
738 /* And make sure that we print immediately */
Thomas Gleixner5b8c4f22010-09-07 14:33:43 +0000739 sema_init(&console_sem, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740}
741
742#if defined(CONFIG_PRINTK_TIME)
743static int printk_time = 1;
744#else
745static int printk_time = 0;
746#endif
Randy Dunlape84845c2007-07-15 23:40:25 -0700747module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748
Michael Ellerman76a8ad22006-06-25 05:47:40 -0700749/* Check if we have any console registered that can be called early in boot. */
750static int have_callable_console(void)
751{
752 struct console *con;
753
Robin Getz4d091612009-07-01 21:08:37 -0400754 for_each_console(con)
Michael Ellerman76a8ad22006-06-25 05:47:40 -0700755 if (con->flags & CON_ANYTIME)
756 return 1;
757
758 return 0;
759}
760
Martin Waitzddad86c2005-11-13 16:08:14 -0800761/**
762 * printk - print a kernel message
763 * @fmt: format string
764 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800765 * This is printk(). It can be called from any context. We want it to work.
Jesper Juhl40dc5652005-10-30 15:02:46 -0800766 *
Torben Hohnac751ef2011-01-25 15:07:35 -0800767 * We try to grab the console_lock. If we succeed, it's easy - we log the output and
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768 * call the console drivers. If we fail to get the semaphore we place the output
769 * into the log buffer and return. The current holder of the console_sem will
Torben Hohnac751ef2011-01-25 15:07:35 -0800770 * notice the new output in console_unlock(); and will send it to the
771 * consoles before releasing the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700772 *
773 * One effect of this deferred printing is that code which calls printk() and
774 * then changes console_loglevel may break. This is because console_loglevel
775 * is inspected when the actual printing occurs.
Martin Waitzddad86c2005-11-13 16:08:14 -0800776 *
777 * See also:
778 * printf(3)
Andi Kleen20036fd2008-10-15 22:02:02 -0700779 *
780 * See the vsnprintf() documentation for format string extensions over C99.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 */
Matt Mackalld59745c2005-05-01 08:59:02 -0700782
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783asmlinkage int printk(const char *fmt, ...)
784{
785 va_list args;
786 int r;
Laura Abbottaa9b60b2012-01-23 13:06:20 -0800787#ifdef CONFIG_MSM_RTB
788 void *caller = __builtin_return_address(0);
789
790 uncached_logk_pc(LOGK_LOGBUF, caller, (void *)log_end);
791#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792
Jason Wesseld37d39a2010-05-20 21:04:27 -0500793#ifdef CONFIG_KGDB_KDB
794 if (unlikely(kdb_trap_printk)) {
795 va_start(args, fmt);
796 r = vkdb_printf(fmt, args);
797 va_end(args);
798 return r;
799 }
800#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 va_start(args, fmt);
802 r = vprintk(fmt, args);
803 va_end(args);
804
805 return r;
806}
807
David Howellsfe217732005-09-06 15:16:34 -0700808/* cpu currently holding logbuf_lock */
809static volatile unsigned int printk_cpu = UINT_MAX;
810
Linus Torvalds266c2e02008-03-24 19:25:08 -0700811/*
812 * Can we actually use the console at this time on this cpu?
813 *
814 * Console drivers may assume that per-cpu resources have
815 * been allocated. So unless they're explicitly marked as
816 * being able to cope (CON_ANYTIME) don't call them until
817 * this CPU is officially up.
818 */
819static inline int can_use_console(unsigned int cpu)
820{
821 return cpu_online(cpu) || have_callable_console();
822}
823
824/*
825 * Try to get console ownership to actually show the kernel
826 * messages from a 'printk'. Return true (and with the
Torben Hohnac751ef2011-01-25 15:07:35 -0800827 * console_lock held, and 'console_locked' set) if it
Linus Torvalds266c2e02008-03-24 19:25:08 -0700828 * is successful, false otherwise.
829 *
830 * This gets called with the 'logbuf_lock' spinlock held and
831 * interrupts disabled. It should return with 'lockbuf_lock'
832 * released but interrupts still disabled.
833 */
Torben Hohnac751ef2011-01-25 15:07:35 -0800834static int console_trylock_for_printk(unsigned int cpu)
Namhyung Kim8155c022010-10-26 14:22:47 -0700835 __releases(&logbuf_lock)
Linus Torvalds266c2e02008-03-24 19:25:08 -0700836{
837 int retval = 0;
838
Torben Hohnac751ef2011-01-25 15:07:35 -0800839 if (console_trylock()) {
Linus Torvalds093a07e2008-04-15 13:09:54 -0700840 retval = 1;
841
842 /*
843 * If we can't use the console, we need to release
844 * the console semaphore by hand to avoid flushing
845 * the buffer. We need to hold the console semaphore
846 * in order to do this test safely.
847 */
848 if (!can_use_console(cpu)) {
849 console_locked = 0;
850 up(&console_sem);
851 retval = 0;
852 }
853 }
Linus Torvalds266c2e02008-03-24 19:25:08 -0700854 printk_cpu = UINT_MAX;
855 spin_unlock(&logbuf_lock);
856 return retval;
857}
Tejun Heo3b8945e2008-05-12 21:21:04 +0200858static const char recursion_bug_msg [] =
859 KERN_CRIT "BUG: recent printk recursion!\n";
860static int recursion_bug;
Jiri Kosinaedb123e2008-12-04 12:39:49 +0100861static int new_text_line = 1;
Tejun Heo3b8945e2008-05-12 21:21:04 +0200862static char printk_buf[1024];
Ingo Molnar32a76002008-01-25 21:07:58 +0100863
Dave Youngaf913222009-09-22 16:43:33 -0700864int printk_delay_msec __read_mostly;
865
866static inline void printk_delay(void)
867{
868 if (unlikely(printk_delay_msec)) {
869 int m = printk_delay_msec;
870
871 while (m--) {
872 mdelay(1);
873 touch_nmi_watchdog();
874 }
875 }
876}
877
Linus Torvalds1da177e2005-04-16 15:20:36 -0700878asmlinkage int vprintk(const char *fmt, va_list args)
879{
Ingo Molnar32a76002008-01-25 21:07:58 +0100880 int printed_len = 0;
Nick Andrew09159302008-05-12 21:21:04 +0200881 int current_log_level = default_message_loglevel;
Nick Andrewac60ad72008-05-12 21:21:04 +0200882 unsigned long flags;
Ingo Molnar32a76002008-01-25 21:07:58 +0100883 int this_cpu;
884 char *p;
Kay Sievers9d90c8d2011-03-13 03:19:51 +0100885 size_t plen;
886 char special;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700888 boot_delay_msec();
Dave Youngaf913222009-09-22 16:43:33 -0700889 printk_delay();
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700890
David Howellsfe217732005-09-06 15:16:34 -0700891 preempt_disable();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892 /* This stops the holder of console_sem just where we want him */
Mathieu Desnoyers1efc5da2007-02-10 01:46:29 -0800893 raw_local_irq_save(flags);
Ingo Molnar32a76002008-01-25 21:07:58 +0100894 this_cpu = smp_processor_id();
895
896 /*
897 * Ouch, printk recursed into itself!
898 */
899 if (unlikely(printk_cpu == this_cpu)) {
900 /*
901 * If a crash is occurring during printk() on this CPU,
902 * then try to get the crash message out but make sure
903 * we can't deadlock. Otherwise just return to avoid the
904 * recursion and return - but flag the recursion so that
905 * it can be printed at the next appropriate moment:
906 */
907 if (!oops_in_progress) {
Tejun Heo3b8945e2008-05-12 21:21:04 +0200908 recursion_bug = 1;
Ingo Molnar32a76002008-01-25 21:07:58 +0100909 goto out_restore_irqs;
910 }
911 zap_locks();
912 }
913
Ingo Molnara0f1ccf2006-07-03 00:24:58 -0700914 lockdep_off();
915 spin_lock(&logbuf_lock);
Ingo Molnar32a76002008-01-25 21:07:58 +0100916 printk_cpu = this_cpu;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917
Tejun Heo3b8945e2008-05-12 21:21:04 +0200918 if (recursion_bug) {
919 recursion_bug = 0;
920 strcpy(printk_buf, recursion_bug_msg);
Hiroshi Shimamoto26cc2712008-12-19 10:23:03 -0800921 printed_len = strlen(recursion_bug_msg);
Ingo Molnar32a76002008-01-25 21:07:58 +0100922 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 /* Emit the output into the temporary buffer */
Ingo Molnar32a76002008-01-25 21:07:58 +0100924 printed_len += vscnprintf(printk_buf + printed_len,
Tejun Heocf3680b2008-02-14 10:32:07 +0900925 sizeof(printk_buf) - printed_len, fmt, args);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700926
Tony Lindgren76b39902005-05-09 14:10:26 -0700927
Linus Torvalds5fd29d62009-06-16 10:57:02 -0700928 p = printk_buf;
929
Kay Sievers9d90c8d2011-03-13 03:19:51 +0100930 /* Read log level and handle special printk prefix */
931 plen = log_prefix(p, &current_log_level, &special);
932 if (plen) {
933 p += plen;
934
935 switch (special) {
936 case 'c': /* Strip <c> KERN_CONT, continue line */
937 plen = 0;
938 break;
939 case 'd': /* Strip <d> KERN_DEFAULT, start new line */
940 plen = 0;
941 default:
942 if (!new_text_line) {
943 emit_log_char('\n');
944 new_text_line = 1;
Linus Torvalds5fd29d62009-06-16 10:57:02 -0700945 }
946 }
947 }
948
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949 /*
Kay Sievers9d90c8d2011-03-13 03:19:51 +0100950 * Copy the output into log_buf. If the caller didn't provide
951 * the appropriate log prefix, we insert them here
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952 */
Kay Sievers9d90c8d2011-03-13 03:19:51 +0100953 for (; *p; p++) {
Nick Andrewac60ad72008-05-12 21:21:04 +0200954 if (new_text_line) {
Nick Andrewac60ad72008-05-12 21:21:04 +0200955 new_text_line = 0;
956
Kay Sievers9d90c8d2011-03-13 03:19:51 +0100957 if (plen) {
958 /* Copy original log prefix */
959 int i;
960
961 for (i = 0; i < plen; i++)
962 emit_log_char(printk_buf[i]);
963 printed_len += plen;
964 } else {
965 /* Add log prefix */
966 emit_log_char('<');
967 emit_log_char(current_log_level + '0');
968 emit_log_char('>');
969 printed_len += 3;
970 }
971
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972 if (printk_time) {
Kay Sievers9d90c8d2011-03-13 03:19:51 +0100973 /* Add the current time stamp */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 char tbuf[50], *tp;
975 unsigned tlen;
976 unsigned long long t;
977 unsigned long nanosec_rem;
978
Ingo Molnar326e96b2008-01-27 08:03:54 +0100979 t = cpu_clock(printk_cpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 nanosec_rem = do_div(t, 1000000000);
Nick Andrewac60ad72008-05-12 21:21:04 +0200981 tlen = sprintf(tbuf, "[%5lu.%06lu] ",
982 (unsigned long) t,
983 nanosec_rem / 1000);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700984
985 for (tp = tbuf; tp < tbuf + tlen; tp++)
986 emit_log_char(*tp);
Guillaume Chazarain025510c2006-01-08 01:02:41 -0800987 printed_len += tlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700988 }
Nick Andrewac60ad72008-05-12 21:21:04 +0200989
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990 if (!*p)
991 break;
992 }
Nick Andrewac60ad72008-05-12 21:21:04 +0200993
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994 emit_log_char(*p);
995 if (*p == '\n')
Nick Andrewac60ad72008-05-12 21:21:04 +0200996 new_text_line = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 }
998
Linus Torvalds266c2e02008-03-24 19:25:08 -0700999 /*
1000 * Try to acquire and then immediately release the
1001 * console semaphore. The release will do all the
1002 * actual magic (print out buffers, wake up klogd,
1003 * etc).
1004 *
Torben Hohnac751ef2011-01-25 15:07:35 -08001005 * The console_trylock_for_printk() function
Linus Torvalds266c2e02008-03-24 19:25:08 -07001006 * will release 'logbuf_lock' regardless of whether it
1007 * actually gets the semaphore or not.
1008 */
Torben Hohnac751ef2011-01-25 15:07:35 -08001009 if (console_trylock_for_printk(this_cpu))
1010 console_unlock();
Michael Ellerman76a8ad22006-06-25 05:47:40 -07001011
Linus Torvalds266c2e02008-03-24 19:25:08 -07001012 lockdep_on();
Ingo Molnar32a76002008-01-25 21:07:58 +01001013out_restore_irqs:
Linus Torvalds266c2e02008-03-24 19:25:08 -07001014 raw_local_irq_restore(flags);
Michael Ellerman76a8ad22006-06-25 05:47:40 -07001015
David Howellsfe217732005-09-06 15:16:34 -07001016 preempt_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017 return printed_len;
1018}
1019EXPORT_SYMBOL(printk);
1020EXPORT_SYMBOL(vprintk);
1021
Matt Mackalld59745c2005-05-01 08:59:02 -07001022#else
1023
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -08001024static void call_console_drivers(unsigned start, unsigned end)
Jesper Juhl40dc5652005-10-30 15:02:46 -08001025{
1026}
Matt Mackalld59745c2005-05-01 08:59:02 -07001027
1028#endif
1029
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001030static int __add_preferred_console(char *name, int idx, char *options,
1031 char *brl_options)
1032{
1033 struct console_cmdline *c;
1034 int i;
1035
1036 /*
1037 * See if this tty is not yet registered, and
1038 * if we have a slot free.
1039 */
1040 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
1041 if (strcmp(console_cmdline[i].name, name) == 0 &&
1042 console_cmdline[i].index == idx) {
1043 if (!brl_options)
1044 selected_console = i;
1045 return 0;
1046 }
1047 if (i == MAX_CMDLINECONSOLES)
1048 return -E2BIG;
1049 if (!brl_options)
1050 selected_console = i;
1051 c = &console_cmdline[i];
1052 strlcpy(c->name, name, sizeof(c->name));
1053 c->options = options;
1054#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1055 c->brl_options = brl_options;
1056#endif
1057 c->index = idx;
1058 return 0;
1059}
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001060/*
1061 * Set up a list of consoles. Called from init/main.c
1062 */
1063static int __init console_setup(char *str)
1064{
Yinghai Lueaa944a2007-07-15 23:37:27 -07001065 char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001066 char *s, *options, *brl_options = NULL;
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001067 int idx;
1068
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001069#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1070 if (!memcmp(str, "brl,", 4)) {
1071 brl_options = "";
1072 str += 4;
1073 } else if (!memcmp(str, "brl=", 4)) {
1074 brl_options = str + 4;
1075 str = strchr(brl_options, ',');
1076 if (!str) {
1077 printk(KERN_ERR "need port name after brl=\n");
1078 return 1;
1079 }
1080 *(str++) = 0;
1081 }
1082#endif
1083
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001084 /*
1085 * Decode str into name, index, options.
1086 */
1087 if (str[0] >= '0' && str[0] <= '9') {
Yinghai Lueaa944a2007-07-15 23:37:27 -07001088 strcpy(buf, "ttyS");
1089 strncpy(buf + 4, str, sizeof(buf) - 5);
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001090 } else {
Yinghai Lueaa944a2007-07-15 23:37:27 -07001091 strncpy(buf, str, sizeof(buf) - 1);
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001092 }
Yinghai Lueaa944a2007-07-15 23:37:27 -07001093 buf[sizeof(buf) - 1] = 0;
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001094 if ((options = strchr(str, ',')) != NULL)
1095 *(options++) = 0;
1096#ifdef __sparc__
1097 if (!strcmp(str, "ttya"))
Yinghai Lueaa944a2007-07-15 23:37:27 -07001098 strcpy(buf, "ttyS0");
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001099 if (!strcmp(str, "ttyb"))
Yinghai Lueaa944a2007-07-15 23:37:27 -07001100 strcpy(buf, "ttyS1");
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001101#endif
Yinghai Lueaa944a2007-07-15 23:37:27 -07001102 for (s = buf; *s; s++)
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001103 if ((*s >= '0' && *s <= '9') || *s == ',')
1104 break;
1105 idx = simple_strtoul(s, NULL, 10);
1106 *s = 0;
1107
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001108 __add_preferred_console(buf, idx, options, brl_options);
Markus Armbruster9e124fe2008-05-26 23:31:07 +01001109 console_set_on_cmdline = 1;
John Z. Bohach2ea1c532006-03-24 03:18:19 -08001110 return 1;
1111}
1112__setup("console=", console_setup);
1113
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114/**
Matt Mackall3c0547b2005-05-16 21:53:47 -07001115 * add_preferred_console - add a device to the list of preferred consoles.
Martin Waitzddad86c2005-11-13 16:08:14 -08001116 * @name: device name
1117 * @idx: device index
1118 * @options: options for this console
Matt Mackall3c0547b2005-05-16 21:53:47 -07001119 *
1120 * The last preferred console added will be used for kernel messages
1121 * and stdin/out/err for init. Normally this is used by console_setup
1122 * above to handle user-supplied console arguments; however it can also
1123 * be used by arch-specific code either to override the user or more
1124 * commonly to provide a default console (ie from PROM variables) when
1125 * the user has not supplied one.
1126 */
David S. Millerfb445ee2007-12-29 01:19:49 -08001127int add_preferred_console(char *name, int idx, char *options)
Matt Mackall3c0547b2005-05-16 21:53:47 -07001128{
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001129 return __add_preferred_console(name, idx, options, NULL);
Matt Mackall3c0547b2005-05-16 21:53:47 -07001130}
1131
Daniel Ritzb6b1d872007-08-03 16:07:43 +02001132int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
Yinghai Lu18a8bd92007-07-15 23:37:59 -07001133{
1134 struct console_cmdline *c;
1135 int i;
1136
1137 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
1138 if (strcmp(console_cmdline[i].name, name) == 0 &&
1139 console_cmdline[i].index == idx) {
1140 c = &console_cmdline[i];
Markus Armbrusterf7352952008-04-30 00:54:52 -07001141 strlcpy(c->name, name_new, sizeof(c->name));
Yinghai Lu18a8bd92007-07-15 23:37:59 -07001142 c->name[sizeof(c->name) - 1] = 0;
1143 c->options = options;
1144 c->index = idx_new;
1145 return i;
1146 }
1147 /* not found */
1148 return -1;
1149}
1150
Andres Salomon8f4ce8c2007-10-18 03:04:50 -07001151int console_suspend_enabled = 1;
1152EXPORT_SYMBOL(console_suspend_enabled);
1153
1154static int __init console_suspend_disable(char *str)
1155{
1156 console_suspend_enabled = 0;
1157 return 1;
1158}
1159__setup("no_console_suspend", console_suspend_disable);
1160
Matt Mackall3c0547b2005-05-16 21:53:47 -07001161/**
Linus Torvalds557240b2006-06-19 18:16:01 -07001162 * suspend_console - suspend the console subsystem
1163 *
1164 * This disables printk() while we go into suspend states
1165 */
1166void suspend_console(void)
1167{
Andres Salomon8f4ce8c2007-10-18 03:04:50 -07001168 if (!console_suspend_enabled)
1169 return;
Pavel Machek0d630812008-07-23 21:28:32 -07001170 printk("Suspending console(s) (use no_console_suspend to debug)\n");
Torben Hohnac751ef2011-01-25 15:07:35 -08001171 console_lock();
Linus Torvalds557240b2006-06-19 18:16:01 -07001172 console_suspended = 1;
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001173 up(&console_sem);
Linus Torvalds557240b2006-06-19 18:16:01 -07001174}
1175
1176void resume_console(void)
1177{
Andres Salomon8f4ce8c2007-10-18 03:04:50 -07001178 if (!console_suspend_enabled)
1179 return;
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001180 down(&console_sem);
Linus Torvalds557240b2006-06-19 18:16:01 -07001181 console_suspended = 0;
Torben Hohnac751ef2011-01-25 15:07:35 -08001182 console_unlock();
Linus Torvalds557240b2006-06-19 18:16:01 -07001183}
1184
Bryan Huntsman3f2bc4d2011-08-16 17:27:22 -07001185static void __cpuinit console_flush(struct work_struct *work)
1186{
1187 console_lock();
1188 console_unlock();
1189}
1190
1191static __cpuinitdata DECLARE_WORK(console_cpu_notify_work, console_flush);
1192
Linus Torvalds557240b2006-06-19 18:16:01 -07001193/**
Kevin Cernekee034260d2010-06-03 22:11:25 -07001194 * console_cpu_notify - print deferred console messages after CPU hotplug
1195 * @self: notifier struct
1196 * @action: CPU hotplug event
1197 * @hcpu: unused
1198 *
1199 * If printk() is called from a CPU that is not online yet, the messages
1200 * will be spooled but will not show up on the console. This function is
1201 * called when a new CPU comes online (or fails to come up), and ensures
1202 * that any such output gets printed.
Bryan Huntsman3f2bc4d2011-08-16 17:27:22 -07001203 *
1204 * Special handling must be done for cases invoked from an atomic context,
1205 * as we can't be taking the console semaphore here.
Kevin Cernekee034260d2010-06-03 22:11:25 -07001206 */
1207static int __cpuinit console_cpu_notify(struct notifier_block *self,
1208 unsigned long action, void *hcpu)
1209{
1210 switch (action) {
1211 case CPU_ONLINE:
1212 case CPU_DEAD:
Kevin Cernekee034260d2010-06-03 22:11:25 -07001213 case CPU_DOWN_FAILED:
1214 case CPU_UP_CANCELED:
Torben Hohnac751ef2011-01-25 15:07:35 -08001215 console_lock();
1216 console_unlock();
Bryan Huntsman3f2bc4d2011-08-16 17:27:22 -07001217 /* invoked with preemption disabled, so defer */
1218 case CPU_DYING:
1219 if (!console_trylock())
1220 schedule_work(&console_cpu_notify_work);
1221 else
1222 console_unlock();
Kevin Cernekee034260d2010-06-03 22:11:25 -07001223 }
1224 return NOTIFY_OK;
1225}
1226
1227/**
Torben Hohnac751ef2011-01-25 15:07:35 -08001228 * console_lock - lock the console system for exclusive use.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229 *
Torben Hohnac751ef2011-01-25 15:07:35 -08001230 * Acquires a lock which guarantees that the caller has
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231 * exclusive access to the console system and the console_drivers list.
1232 *
1233 * Can sleep, returns nothing.
1234 */
Torben Hohnac751ef2011-01-25 15:07:35 -08001235void console_lock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236{
Eric Sesterhenn8abd8e22006-04-01 01:21:17 +02001237 BUG_ON(in_interrupt());
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 down(&console_sem);
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001239 if (console_suspended)
1240 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001241 console_locked = 1;
1242 console_may_schedule = 1;
1243}
Torben Hohnac751ef2011-01-25 15:07:35 -08001244EXPORT_SYMBOL(console_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001245
Torben Hohnac751ef2011-01-25 15:07:35 -08001246/**
1247 * console_trylock - try to lock the console system for exclusive use.
1248 *
1249 * Tried to acquire a lock which guarantees that the caller has
1250 * exclusive access to the console system and the console_drivers list.
1251 *
1252 * returns 1 on success, and 0 on failure to acquire the lock.
1253 */
1254int console_trylock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001255{
1256 if (down_trylock(&console_sem))
Torben Hohnac751ef2011-01-25 15:07:35 -08001257 return 0;
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001258 if (console_suspended) {
1259 up(&console_sem);
Torben Hohnac751ef2011-01-25 15:07:35 -08001260 return 0;
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001261 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001262 console_locked = 1;
1263 console_may_schedule = 0;
Torben Hohnac751ef2011-01-25 15:07:35 -08001264 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001265}
Torben Hohnac751ef2011-01-25 15:07:35 -08001266EXPORT_SYMBOL(console_trylock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001267
1268int is_console_locked(void)
1269{
1270 return console_locked;
1271}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272
Peter Zijlstrab845b512008-08-08 21:47:09 +02001273static DEFINE_PER_CPU(int, printk_pending);
1274
1275void printk_tick(void)
1276{
Eric Dumazet40dc11f2010-11-26 17:22:16 +01001277 if (__this_cpu_read(printk_pending)) {
1278 __this_cpu_write(printk_pending, 0);
Peter Zijlstrab845b512008-08-08 21:47:09 +02001279 wake_up_interruptible(&log_wait);
1280 }
1281}
1282
1283int printk_needs_cpu(int cpu)
1284{
Eric Dumazet40dc11f2010-11-26 17:22:16 +01001285 if (cpu_is_offline(cpu))
Heiko Carstens61ab2542010-11-26 13:00:59 +01001286 printk_tick();
Eric Dumazet40dc11f2010-11-26 17:22:16 +01001287 return __this_cpu_read(printk_pending);
Peter Zijlstrab845b512008-08-08 21:47:09 +02001288}
1289
Kirill Korotaeve3e8a752007-02-10 01:46:19 -08001290void wake_up_klogd(void)
1291{
Peter Zijlstrab845b512008-08-08 21:47:09 +02001292 if (waitqueue_active(&log_wait))
Heiko Carstens49f41382010-11-26 13:42:47 +01001293 this_cpu_write(printk_pending, 1);
Kirill Korotaeve3e8a752007-02-10 01:46:19 -08001294}
1295
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296/**
Torben Hohnac751ef2011-01-25 15:07:35 -08001297 * console_unlock - unlock the console system
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298 *
Torben Hohnac751ef2011-01-25 15:07:35 -08001299 * Releases the console_lock which the caller holds on the console system
Linus Torvalds1da177e2005-04-16 15:20:36 -07001300 * and the console driver list.
1301 *
Torben Hohnac751ef2011-01-25 15:07:35 -08001302 * While the console_lock was held, console output may have been buffered
1303 * by printk(). If this is the case, console_unlock(); emits
1304 * the output prior to releasing the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001305 *
1306 * If there is output waiting for klogd, we wake it up.
1307 *
Torben Hohnac751ef2011-01-25 15:07:35 -08001308 * console_unlock(); may be called from any context.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309 */
Torben Hohnac751ef2011-01-25 15:07:35 -08001310void console_unlock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311{
1312 unsigned long flags;
Denys Vlasenkoeed4a2a2008-02-06 01:37:02 -08001313 unsigned _con_start, _log_end;
1314 unsigned wake_klogd = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315
Linus Torvalds557240b2006-06-19 18:16:01 -07001316 if (console_suspended) {
Arve Hjønnevåg403f3072009-02-14 02:07:24 +01001317 up(&console_sem);
Linus Torvalds557240b2006-06-19 18:16:01 -07001318 return;
1319 }
Antonino A. Daplas78944e52006-08-05 12:14:16 -07001320
1321 console_may_schedule = 0;
1322
Linus Torvalds1da177e2005-04-16 15:20:36 -07001323 for ( ; ; ) {
1324 spin_lock_irqsave(&logbuf_lock, flags);
1325 wake_klogd |= log_start - log_end;
1326 if (con_start == log_end)
1327 break; /* Nothing to print */
1328 _con_start = con_start;
1329 _log_end = log_end;
1330 con_start = log_end; /* Flush */
1331 spin_unlock(&logbuf_lock);
Steven Rostedt81d68a92008-05-12 21:20:42 +02001332 stop_critical_timings(); /* don't trace print latency */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333 call_console_drivers(_con_start, _log_end);
Steven Rostedt81d68a92008-05-12 21:20:42 +02001334 start_critical_timings();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335 local_irq_restore(flags);
1336 }
1337 console_locked = 0;
Feng Tangfe3d8ad2011-03-22 16:34:21 -07001338
1339 /* Release the exclusive_console once it is used */
1340 if (unlikely(exclusive_console))
1341 exclusive_console = NULL;
1342
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343 up(&console_sem);
1344 spin_unlock_irqrestore(&logbuf_lock, flags);
Kirill Korotaeve3e8a752007-02-10 01:46:19 -08001345 if (wake_klogd)
1346 wake_up_klogd();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347}
Torben Hohnac751ef2011-01-25 15:07:35 -08001348EXPORT_SYMBOL(console_unlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349
Martin Waitzddad86c2005-11-13 16:08:14 -08001350/**
1351 * console_conditional_schedule - yield the CPU if required
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352 *
1353 * If the console code is currently allowed to sleep, and
1354 * if this CPU should yield the CPU to another task, do
1355 * so here.
1356 *
Torben Hohnac751ef2011-01-25 15:07:35 -08001357 * Must be called within console_lock();.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358 */
1359void __sched console_conditional_schedule(void)
1360{
1361 if (console_may_schedule)
1362 cond_resched();
1363}
1364EXPORT_SYMBOL(console_conditional_schedule);
1365
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366void console_unblank(void)
1367{
1368 struct console *c;
1369
1370 /*
1371 * console_unblank can no longer be called in interrupt context unless
1372 * oops_in_progress is set to 1..
1373 */
1374 if (oops_in_progress) {
1375 if (down_trylock(&console_sem) != 0)
1376 return;
1377 } else
Torben Hohnac751ef2011-01-25 15:07:35 -08001378 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379
1380 console_locked = 1;
1381 console_may_schedule = 0;
Robin Getz4d091612009-07-01 21:08:37 -04001382 for_each_console(c)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 if ((c->flags & CON_ENABLED) && c->unblank)
1384 c->unblank();
Torben Hohnac751ef2011-01-25 15:07:35 -08001385 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387
1388/*
1389 * Return the console tty driver structure and its associated index
1390 */
1391struct tty_driver *console_device(int *index)
1392{
1393 struct console *c;
1394 struct tty_driver *driver = NULL;
1395
Torben Hohnac751ef2011-01-25 15:07:35 -08001396 console_lock();
Robin Getz4d091612009-07-01 21:08:37 -04001397 for_each_console(c) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 if (!c->device)
1399 continue;
1400 driver = c->device(c, index);
1401 if (driver)
1402 break;
1403 }
Torben Hohnac751ef2011-01-25 15:07:35 -08001404 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405 return driver;
1406}
1407
1408/*
1409 * Prevent further output on the passed console device so that (for example)
1410 * serial drivers can disable console output before suspending a port, and can
1411 * re-enable output afterwards.
1412 */
1413void console_stop(struct console *console)
1414{
Torben Hohnac751ef2011-01-25 15:07:35 -08001415 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416 console->flags &= ~CON_ENABLED;
Torben Hohnac751ef2011-01-25 15:07:35 -08001417 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418}
1419EXPORT_SYMBOL(console_stop);
1420
1421void console_start(struct console *console)
1422{
Torben Hohnac751ef2011-01-25 15:07:35 -08001423 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424 console->flags |= CON_ENABLED;
Torben Hohnac751ef2011-01-25 15:07:35 -08001425 console_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426}
1427EXPORT_SYMBOL(console_start);
1428
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -07001429static int __read_mostly keep_bootcon;
1430
1431static int __init keep_bootcon_setup(char *str)
1432{
1433 keep_bootcon = 1;
1434 printk(KERN_INFO "debug: skip boot console de-registration.\n");
1435
1436 return 0;
1437}
1438
1439early_param("keep_bootcon", keep_bootcon_setup);
1440
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441/*
1442 * The console driver calls this routine during kernel initialization
1443 * to register the console printing procedure with printk() and to
1444 * print any messages that were printed by the kernel before the
1445 * console driver was initialized.
Robin Getz4d091612009-07-01 21:08:37 -04001446 *
1447 * This can happen pretty early during the boot process (because of
1448 * early_printk) - sometimes before setup_arch() completes - be careful
1449 * of what kernel features are used - they may not be initialised yet.
1450 *
1451 * There are two types of consoles - bootconsoles (early_printk) and
1452 * "real" consoles (everything which is not a bootconsole) which are
1453 * handled differently.
1454 * - Any number of bootconsoles can be registered at any time.
1455 * - As soon as a "real" console is registered, all bootconsoles
1456 * will be unregistered automatically.
1457 * - Once a "real" console is registered, any attempt to register a
1458 * bootconsoles will be rejected
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459 */
Robin Getz4d091612009-07-01 21:08:37 -04001460void register_console(struct console *newcon)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461{
Jesper Juhl40dc5652005-10-30 15:02:46 -08001462 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463 unsigned long flags;
Robin Getz4d091612009-07-01 21:08:37 -04001464 struct console *bcon = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465
Robin Getz4d091612009-07-01 21:08:37 -04001466 /*
1467 * before we register a new CON_BOOT console, make sure we don't
1468 * already have a valid console
1469 */
1470 if (console_drivers && newcon->flags & CON_BOOT) {
1471 /* find the last or real console */
1472 for_each_console(bcon) {
1473 if (!(bcon->flags & CON_BOOT)) {
1474 printk(KERN_INFO "Too late to register bootconsole %s%d\n",
1475 newcon->name, newcon->index);
1476 return;
1477 }
1478 }
Gerd Hoffmann69331af2007-05-08 00:26:49 -07001479 }
1480
Robin Getz4d091612009-07-01 21:08:37 -04001481 if (console_drivers && console_drivers->flags & CON_BOOT)
1482 bcon = console_drivers;
1483
1484 if (preferred_console < 0 || bcon || !console_drivers)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485 preferred_console = selected_console;
1486
Robin Getz4d091612009-07-01 21:08:37 -04001487 if (newcon->early_setup)
1488 newcon->early_setup();
Yinghai Lu18a8bd92007-07-15 23:37:59 -07001489
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 /*
1491 * See if we want to use this console driver. If we
1492 * didn't select a console we take the first one
1493 * that registers here.
1494 */
1495 if (preferred_console < 0) {
Robin Getz4d091612009-07-01 21:08:37 -04001496 if (newcon->index < 0)
1497 newcon->index = 0;
1498 if (newcon->setup == NULL ||
1499 newcon->setup(newcon, NULL) == 0) {
1500 newcon->flags |= CON_ENABLED;
1501 if (newcon->device) {
1502 newcon->flags |= CON_CONSDEV;
Jan Kiszkacd3a1b82008-05-12 21:21:04 +02001503 preferred_console = 0;
1504 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 }
1506 }
1507
1508 /*
1509 * See if this console matches one we selected on
1510 * the command line.
1511 */
Jesper Juhl40dc5652005-10-30 15:02:46 -08001512 for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
1513 i++) {
Robin Getz4d091612009-07-01 21:08:37 -04001514 if (strcmp(console_cmdline[i].name, newcon->name) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515 continue;
Robin Getz4d091612009-07-01 21:08:37 -04001516 if (newcon->index >= 0 &&
1517 newcon->index != console_cmdline[i].index)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001518 continue;
Robin Getz4d091612009-07-01 21:08:37 -04001519 if (newcon->index < 0)
1520 newcon->index = console_cmdline[i].index;
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001521#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1522 if (console_cmdline[i].brl_options) {
Robin Getz4d091612009-07-01 21:08:37 -04001523 newcon->flags |= CON_BRL;
1524 braille_register_console(newcon,
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001525 console_cmdline[i].index,
1526 console_cmdline[i].options,
1527 console_cmdline[i].brl_options);
1528 return;
1529 }
1530#endif
Robin Getz4d091612009-07-01 21:08:37 -04001531 if (newcon->setup &&
1532 newcon->setup(newcon, console_cmdline[i].options) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533 break;
Robin Getz4d091612009-07-01 21:08:37 -04001534 newcon->flags |= CON_ENABLED;
1535 newcon->index = console_cmdline[i].index;
Greg Edwardsab4af032005-06-23 00:09:05 -07001536 if (i == selected_console) {
Robin Getz4d091612009-07-01 21:08:37 -04001537 newcon->flags |= CON_CONSDEV;
Greg Edwardsab4af032005-06-23 00:09:05 -07001538 preferred_console = selected_console;
1539 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540 break;
1541 }
1542
Robin Getz4d091612009-07-01 21:08:37 -04001543 if (!(newcon->flags & CON_ENABLED))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544 return;
1545
Robin Getz8259cf42009-07-09 13:08:37 -04001546 /*
1547 * If we have a bootconsole, and are switching to a real console,
1548 * don't print everything out again, since when the boot console, and
1549 * the real console are the same physical device, it's annoying to
1550 * see the beginning boot messages twice
1551 */
1552 if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
Robin Getz4d091612009-07-01 21:08:37 -04001553 newcon->flags &= ~CON_PRINTBUFFER;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554
1555 /*
1556 * Put this console in the list - keep the
1557 * preferred driver at the head of the list.
1558 */
Torben Hohnac751ef2011-01-25 15:07:35 -08001559 console_lock();
Robin Getz4d091612009-07-01 21:08:37 -04001560 if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
1561 newcon->next = console_drivers;
1562 console_drivers = newcon;
1563 if (newcon->next)
1564 newcon->next->flags &= ~CON_CONSDEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001565 } else {
Robin Getz4d091612009-07-01 21:08:37 -04001566 newcon->next = console_drivers->next;
1567 console_drivers->next = newcon;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568 }
Robin Getz4d091612009-07-01 21:08:37 -04001569 if (newcon->flags & CON_PRINTBUFFER) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570 /*
Torben Hohnac751ef2011-01-25 15:07:35 -08001571 * console_unlock(); will print out the buffered messages
Linus Torvalds1da177e2005-04-16 15:20:36 -07001572 * for us.
1573 */
1574 spin_lock_irqsave(&logbuf_lock, flags);
1575 con_start = log_start;
1576 spin_unlock_irqrestore(&logbuf_lock, flags);
Feng Tangfe3d8ad2011-03-22 16:34:21 -07001577 /*
1578 * We're about to replay the log buffer. Only do this to the
1579 * just-registered console to avoid excessive message spam to
1580 * the already-registered consoles.
1581 */
1582 exclusive_console = newcon;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583 }
Torben Hohnac751ef2011-01-25 15:07:35 -08001584 console_unlock();
Kay Sieversfbc92a32010-12-01 18:51:05 +01001585 console_sysfs_notify();
Robin Getz8259cf42009-07-09 13:08:37 -04001586
1587 /*
1588 * By unregistering the bootconsoles after we enable the real console
1589 * we get the "console xxx enabled" message on all the consoles -
1590 * boot consoles, real consoles, etc - this is to ensure that end
1591 * users know there might be something in the kernel's log buffer that
1592 * went to the bootconsole (that they do not see on the real console)
1593 */
Fabio M. Di Nitto7bf69392011-03-22 16:34:20 -07001594 if (bcon &&
1595 ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
1596 !keep_bootcon) {
Robin Getz8259cf42009-07-09 13:08:37 -04001597 /* we need to iterate through twice, to make sure we print
1598 * everything out, before we unregister the console(s)
1599 */
1600 printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n",
1601 newcon->name, newcon->index);
1602 for_each_console(bcon)
1603 if (bcon->flags & CON_BOOT)
1604 unregister_console(bcon);
1605 } else {
1606 printk(KERN_INFO "%sconsole [%s%d] enabled\n",
1607 (newcon->flags & CON_BOOT) ? "boot" : "" ,
1608 newcon->name, newcon->index);
1609 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001610}
1611EXPORT_SYMBOL(register_console);
1612
Jesper Juhl40dc5652005-10-30 15:02:46 -08001613int unregister_console(struct console *console)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614{
Jesper Juhl40dc5652005-10-30 15:02:46 -08001615 struct console *a, *b;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616 int res = 1;
1617
Samuel Thibaultf7511d52008-04-30 00:54:51 -07001618#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
1619 if (console->flags & CON_BRL)
1620 return braille_unregister_console(console);
1621#endif
1622
Torben Hohnac751ef2011-01-25 15:07:35 -08001623 console_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624 if (console_drivers == console) {
1625 console_drivers=console->next;
1626 res = 0;
Benjamin Herrenschmidte9b15b52005-11-23 13:37:44 -08001627 } else if (console_drivers) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628 for (a=console_drivers->next, b=console_drivers ;
1629 a; b=a, a=b->next) {
1630 if (a == console) {
1631 b->next = a->next;
1632 res = 0;
1633 break;
Jesper Juhl40dc5652005-10-30 15:02:46 -08001634 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635 }
1636 }
Jesper Juhl40dc5652005-10-30 15:02:46 -08001637
Gerd Hoffmann69331af2007-05-08 00:26:49 -07001638 /*
Greg Edwardsab4af032005-06-23 00:09:05 -07001639 * If this isn't the last console and it has CON_CONSDEV set, we
1640 * need to set it on the next preferred console.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641 */
Gerd Hoffmann69331af2007-05-08 00:26:49 -07001642 if (console_drivers != NULL && console->flags & CON_CONSDEV)
Greg Edwardsab4af032005-06-23 00:09:05 -07001643 console_drivers->flags |= CON_CONSDEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001644
Torben Hohnac751ef2011-01-25 15:07:35 -08001645 console_unlock();
Kay Sieversfbc92a32010-12-01 18:51:05 +01001646 console_sysfs_notify();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001647 return res;
1648}
1649EXPORT_SYMBOL(unregister_console);
Matt Mackalld59745c2005-05-01 08:59:02 -07001650
Kevin Cernekee034260d2010-06-03 22:11:25 -07001651static int __init printk_late_init(void)
Robin Getz0c5564b2007-08-20 15:22:47 -04001652{
Robin Getz4d091612009-07-01 21:08:37 -04001653 struct console *con;
1654
1655 for_each_console(con) {
Nishanth Aravamudan7f4e1562011-08-25 15:59:11 -07001656 if (!keep_bootcon && con->flags & CON_BOOT) {
Robin Getzcb00e992007-08-21 23:14:58 -04001657 printk(KERN_INFO "turn off boot console %s%d\n",
Robin Getz4d091612009-07-01 21:08:37 -04001658 con->name, con->index);
Sonic Zhang42c2c8c2009-08-06 15:58:11 -07001659 unregister_console(con);
Robin Getzcb00e992007-08-21 23:14:58 -04001660 }
Robin Getz0c5564b2007-08-20 15:22:47 -04001661 }
Kevin Cernekee034260d2010-06-03 22:11:25 -07001662 hotcpu_notifier(console_cpu_notify, 0);
Robin Getz0c5564b2007-08-20 15:22:47 -04001663 return 0;
1664}
Kevin Cernekee034260d2010-06-03 22:11:25 -07001665late_initcall(printk_late_init);
Robin Getz0c5564b2007-08-20 15:22:47 -04001666
Joe Perches7ef3d2f2008-02-08 04:21:25 -08001667#if defined CONFIG_PRINTK
Dave Young717115e2008-07-25 01:45:58 -07001668
Linus Torvalds1da177e2005-04-16 15:20:36 -07001669/*
1670 * printk rate limiting, lifted from the networking subsystem.
1671 *
Uwe Kleine-König641de9d2008-07-29 22:33:38 -07001672 * This enforces a rate limit: not more than 10 kernel messages
1673 * every 5s to make a denial-of-service attack impossible.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001674 */
Uwe Kleine-König641de9d2008-07-29 22:33:38 -07001675DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
1676
Christian Borntraeger5c828712009-10-23 14:58:11 +02001677int __printk_ratelimit(const char *func)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678{
Christian Borntraeger5c828712009-10-23 14:58:11 +02001679 return ___ratelimit(&printk_ratelimit_state, func);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680}
Christian Borntraeger5c828712009-10-23 14:58:11 +02001681EXPORT_SYMBOL(__printk_ratelimit);
Andrew Mortonf46c4832006-11-02 22:07:16 -08001682
1683/**
1684 * printk_timed_ratelimit - caller-controlled printk ratelimiting
1685 * @caller_jiffies: pointer to caller's state
1686 * @interval_msecs: minimum interval between prints
1687 *
1688 * printk_timed_ratelimit() returns true if more than @interval_msecs
1689 * milliseconds have elapsed since the last time printk_timed_ratelimit()
1690 * returned true.
1691 */
1692bool printk_timed_ratelimit(unsigned long *caller_jiffies,
1693 unsigned int interval_msecs)
1694{
Guillaume Knispelf2d28a22009-03-17 16:18:42 +01001695 if (*caller_jiffies == 0
1696 || !time_in_range(jiffies, *caller_jiffies,
1697 *caller_jiffies
1698 + msecs_to_jiffies(interval_msecs))) {
1699 *caller_jiffies = jiffies;
Andrew Mortonf46c4832006-11-02 22:07:16 -08001700 return true;
1701 }
1702 return false;
1703}
1704EXPORT_SYMBOL(printk_timed_ratelimit);
Simon Kagstrom456b5652009-10-16 14:09:18 +02001705
1706static DEFINE_SPINLOCK(dump_list_lock);
1707static LIST_HEAD(dump_list);
1708
1709/**
1710 * kmsg_dump_register - register a kernel log dumper.
Randy Dunlap64855362009-12-17 15:27:27 -08001711 * @dumper: pointer to the kmsg_dumper structure
Simon Kagstrom456b5652009-10-16 14:09:18 +02001712 *
1713 * Adds a kernel log dumper to the system. The dump callback in the
1714 * structure will be called when the kernel oopses or panics and must be
1715 * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
1716 */
1717int kmsg_dump_register(struct kmsg_dumper *dumper)
1718{
1719 unsigned long flags;
1720 int err = -EBUSY;
1721
1722 /* The dump callback needs to be set */
1723 if (!dumper->dump)
1724 return -EINVAL;
1725
1726 spin_lock_irqsave(&dump_list_lock, flags);
1727 /* Don't allow registering multiple times */
1728 if (!dumper->registered) {
1729 dumper->registered = 1;
Huang Yingfb842b02011-01-12 16:59:43 -08001730 list_add_tail_rcu(&dumper->list, &dump_list);
Simon Kagstrom456b5652009-10-16 14:09:18 +02001731 err = 0;
1732 }
1733 spin_unlock_irqrestore(&dump_list_lock, flags);
1734
1735 return err;
1736}
1737EXPORT_SYMBOL_GPL(kmsg_dump_register);
1738
1739/**
1740 * kmsg_dump_unregister - unregister a kmsg dumper.
Randy Dunlap64855362009-12-17 15:27:27 -08001741 * @dumper: pointer to the kmsg_dumper structure
Simon Kagstrom456b5652009-10-16 14:09:18 +02001742 *
1743 * Removes a dump device from the system. Returns zero on success and
1744 * %-EINVAL otherwise.
1745 */
1746int kmsg_dump_unregister(struct kmsg_dumper *dumper)
1747{
1748 unsigned long flags;
1749 int err = -EINVAL;
1750
1751 spin_lock_irqsave(&dump_list_lock, flags);
1752 if (dumper->registered) {
1753 dumper->registered = 0;
Huang Yingfb842b02011-01-12 16:59:43 -08001754 list_del_rcu(&dumper->list);
Simon Kagstrom456b5652009-10-16 14:09:18 +02001755 err = 0;
1756 }
1757 spin_unlock_irqrestore(&dump_list_lock, flags);
Huang Yingfb842b02011-01-12 16:59:43 -08001758 synchronize_rcu();
Simon Kagstrom456b5652009-10-16 14:09:18 +02001759
1760 return err;
1761}
1762EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
1763
Simon Kagstrom456b5652009-10-16 14:09:18 +02001764/**
1765 * kmsg_dump - dump kernel log to kernel message dumpers.
1766 * @reason: the reason (oops, panic etc) for dumping
1767 *
1768 * Iterate through each of the dump devices and call the oops/panic
1769 * callbacks with the log buffer.
1770 */
1771void kmsg_dump(enum kmsg_dump_reason reason)
1772{
1773 unsigned long end;
1774 unsigned chars;
1775 struct kmsg_dumper *dumper;
1776 const char *s1, *s2;
1777 unsigned long l1, l2;
1778 unsigned long flags;
1779
1780 /* Theoretically, the log could move on after we do this, but
1781 there's not a lot we can do about that. The new messages
1782 will overwrite the start of what we dump. */
1783 spin_lock_irqsave(&logbuf_lock, flags);
1784 end = log_end & LOG_BUF_MASK;
1785 chars = logged_chars;
1786 spin_unlock_irqrestore(&logbuf_lock, flags);
1787
Andi Kleen8c4af382010-08-09 17:20:36 -07001788 if (chars > end) {
1789 s1 = log_buf + log_buf_len - chars + end;
1790 l1 = chars - end;
Simon Kagstrom456b5652009-10-16 14:09:18 +02001791
1792 s2 = log_buf;
1793 l2 = end;
1794 } else {
1795 s1 = "";
1796 l1 = 0;
1797
Andi Kleen8c4af382010-08-09 17:20:36 -07001798 s2 = log_buf + end - chars;
1799 l2 = chars;
Simon Kagstrom456b5652009-10-16 14:09:18 +02001800 }
1801
Huang Yingfb842b02011-01-12 16:59:43 -08001802 rcu_read_lock();
1803 list_for_each_entry_rcu(dumper, &dump_list, list)
Simon Kagstrom456b5652009-10-16 14:09:18 +02001804 dumper->dump(dumper, reason, s1, l1, s2, l2);
Huang Yingfb842b02011-01-12 16:59:43 -08001805 rcu_read_unlock();
Simon Kagstrom456b5652009-10-16 14:09:18 +02001806}
Joe Perches7ef3d2f2008-02-08 04:21:25 -08001807#endif