Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
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. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 | 15 | * Rewrote bits to get rid of console_lock |
e1f8e874 | 16 | * 01Mar01 Andrew Morton |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
1da177e4 LT |
23 | #include <linux/console.h> |
24 | #include <linux/init.h> | |
bfe8df3d RD |
25 | #include <linux/jiffies.h> |
26 | #include <linux/nmi.h> | |
1da177e4 | 27 | #include <linux/module.h> |
3b9c0410 | 28 | #include <linux/moduleparam.h> |
1da177e4 | 29 | #include <linux/interrupt.h> /* For in_interrupt() */ |
1da177e4 LT |
30 | #include <linux/delay.h> |
31 | #include <linux/smp.h> | |
32 | #include <linux/security.h> | |
33 | #include <linux/bootmem.h> | |
34 | #include <linux/syscalls.h> | |
04d491ab | 35 | #include <linux/kexec.h> |
d37d39ae | 36 | #include <linux/kdb.h> |
3fff4c42 | 37 | #include <linux/ratelimit.h> |
456b565c | 38 | #include <linux/kmsg_dump.h> |
00234592 | 39 | #include <linux/syslog.h> |
034260d6 KC |
40 | #include <linux/cpu.h> |
41 | #include <linux/notifier.h> | |
1da177e4 LT |
42 | |
43 | #include <asm/uaccess.h> | |
44 | ||
4d091611 RG |
45 | /* |
46 | * for_each_console() allows you to iterate on each console | |
47 | */ | |
48 | #define for_each_console(con) \ | |
49 | for (con = console_drivers; con != NULL; con = con->next) | |
50 | ||
076f9776 IM |
51 | /* |
52 | * Architectures can override it: | |
53 | */ | |
e17ba73b | 54 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
076f9776 IM |
55 | { |
56 | } | |
57 | ||
1da177e4 LT |
58 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
59 | ||
60 | /* printk's without a loglevel use this.. */ | |
61 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ | |
62 | ||
63 | /* We show everything that is MORE important than this.. */ | |
64 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
65 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
66 | ||
67 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
68 | ||
69 | int console_printk[4] = { | |
70 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
71 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
72 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
73 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
74 | }; | |
75 | ||
1da177e4 | 76 | /* |
0bbfb7c2 | 77 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
78 | * their unblank() callback or not. So let's export it. |
79 | */ | |
80 | int oops_in_progress; | |
81 | EXPORT_SYMBOL(oops_in_progress); | |
82 | ||
83 | /* | |
84 | * console_sem protects the console_drivers list, and also | |
85 | * provides serialisation for access to the entire console | |
86 | * driver system. | |
87 | */ | |
5b8c4f23 | 88 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 89 | struct console *console_drivers; |
a29d1cfe IM |
90 | EXPORT_SYMBOL_GPL(console_drivers); |
91 | ||
1da177e4 LT |
92 | /* |
93 | * This is used for debugging the mess that is the VT code by | |
94 | * keeping track if we have the console semaphore held. It's | |
95 | * definitely not the perfect debug tool (we don't know if _WE_ | |
96 | * hold it are racing, but it helps tracking those weird code | |
97 | * path in the console code where we end up in places I want | |
98 | * locked without the console sempahore held | |
99 | */ | |
557240b4 | 100 | static int console_locked, console_suspended; |
1da177e4 LT |
101 | |
102 | /* | |
103 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
104 | * It is also used in interesting ways to provide interlocking in | |
105 | * release_console_sem(). | |
106 | */ | |
107 | static DEFINE_SPINLOCK(logbuf_lock); | |
108 | ||
eed4a2ab | 109 | #define LOG_BUF_MASK (log_buf_len-1) |
1da177e4 LT |
110 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
111 | ||
112 | /* | |
113 | * The indices into log_buf are not constrained to log_buf_len - they | |
114 | * must be masked before subscripting | |
115 | */ | |
eed4a2ab DV |
116 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
117 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ | |
118 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
119 | |
120 | /* | |
121 | * Array of consoles built from command line options (console=) | |
122 | */ | |
123 | struct console_cmdline | |
124 | { | |
125 | char name[8]; /* Name of the driver */ | |
126 | int index; /* Minor dev. to use */ | |
127 | char *options; /* Options for the driver */ | |
f7511d5f ST |
128 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
129 | char *brl_options; /* Options for braille driver */ | |
130 | #endif | |
1da177e4 LT |
131 | }; |
132 | ||
133 | #define MAX_CMDLINECONSOLES 8 | |
134 | ||
135 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
136 | static int selected_console = -1; | |
137 | static int preferred_console = -1; | |
9e124fe1 MA |
138 | int console_set_on_cmdline; |
139 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
140 | |
141 | /* Flag: console code may call schedule() */ | |
142 | static int console_may_schedule; | |
143 | ||
d59745ce MM |
144 | #ifdef CONFIG_PRINTK |
145 | ||
146 | static char __log_buf[__LOG_BUF_LEN]; | |
147 | static char *log_buf = __log_buf; | |
148 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 149 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
cea83886 | 150 | static int saved_console_loglevel = -1; |
d59745ce | 151 | |
04d491ab NH |
152 | #ifdef CONFIG_KEXEC |
153 | /* | |
154 | * This appends the listed symbols to /proc/vmcoreinfo | |
155 | * | |
156 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
157 | * obtain access to symbols that are otherwise very difficult to locate. These | |
158 | * symbols are specifically used so that utilities can access and extract the | |
159 | * dmesg log from a vmcore file after a crash. | |
160 | */ | |
161 | void log_buf_kexec_setup(void) | |
162 | { | |
163 | VMCOREINFO_SYMBOL(log_buf); | |
164 | VMCOREINFO_SYMBOL(log_end); | |
165 | VMCOREINFO_SYMBOL(log_buf_len); | |
166 | VMCOREINFO_SYMBOL(logged_chars); | |
167 | } | |
168 | #endif | |
169 | ||
1da177e4 LT |
170 | static int __init log_buf_len_setup(char *str) |
171 | { | |
eed4a2ab | 172 | unsigned size = memparse(str, &str); |
1da177e4 LT |
173 | unsigned long flags; |
174 | ||
175 | if (size) | |
176 | size = roundup_pow_of_two(size); | |
177 | if (size > log_buf_len) { | |
eed4a2ab | 178 | unsigned start, dest_idx, offset; |
40dc5651 | 179 | char *new_log_buf; |
1da177e4 LT |
180 | |
181 | new_log_buf = alloc_bootmem(size); | |
182 | if (!new_log_buf) { | |
40dc5651 | 183 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
184 | goto out; |
185 | } | |
186 | ||
187 | spin_lock_irqsave(&logbuf_lock, flags); | |
188 | log_buf_len = size; | |
189 | log_buf = new_log_buf; | |
190 | ||
191 | offset = start = min(con_start, log_start); | |
192 | dest_idx = 0; | |
193 | while (start != log_end) { | |
194 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
195 | start++; | |
196 | dest_idx++; | |
197 | } | |
198 | log_start -= offset; | |
199 | con_start -= offset; | |
200 | log_end -= offset; | |
201 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
202 | ||
40dc5651 | 203 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
204 | } |
205 | out: | |
1da177e4 LT |
206 | return 1; |
207 | } | |
208 | ||
209 | __setup("log_buf_len=", log_buf_len_setup); | |
210 | ||
bfe8df3d RD |
211 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
212 | ||
674dff65 | 213 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 214 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
215 | |
216 | static int __init boot_delay_setup(char *str) | |
217 | { | |
218 | unsigned long lpj; | |
bfe8df3d RD |
219 | |
220 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
221 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
222 | ||
223 | get_option(&str, &boot_delay); | |
224 | if (boot_delay > 10 * 1000) | |
225 | boot_delay = 0; | |
226 | ||
3a3b6ed2 DY |
227 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
228 | "HZ: %d, loops_per_msec: %llu\n", | |
229 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
bfe8df3d RD |
230 | return 1; |
231 | } | |
232 | __setup("boot_delay=", boot_delay_setup); | |
233 | ||
234 | static void boot_delay_msec(void) | |
235 | { | |
236 | unsigned long long k; | |
237 | unsigned long timeout; | |
238 | ||
239 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
240 | return; | |
241 | ||
3a3b6ed2 | 242 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
243 | |
244 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
245 | while (k) { | |
246 | k--; | |
247 | cpu_relax(); | |
248 | /* | |
249 | * use (volatile) jiffies to prevent | |
250 | * compiler reduction; loop termination via jiffies | |
251 | * is secondary and may or may not happen. | |
252 | */ | |
253 | if (time_after(jiffies, timeout)) | |
254 | break; | |
255 | touch_nmi_watchdog(); | |
256 | } | |
257 | } | |
258 | #else | |
259 | static inline void boot_delay_msec(void) | |
260 | { | |
261 | } | |
262 | #endif | |
263 | ||
eaf06b24 DR |
264 | #ifdef CONFIG_SECURITY_DMESG_RESTRICT |
265 | int dmesg_restrict = 1; | |
266 | #else | |
267 | int dmesg_restrict; | |
268 | #endif | |
269 | ||
00234592 | 270 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
1da177e4 | 271 | { |
eed4a2ab | 272 | unsigned i, j, limit, count; |
1da177e4 LT |
273 | int do_clear = 0; |
274 | char c; | |
275 | int error = 0; | |
276 | ||
12b3052c EP |
277 | /* |
278 | * If this is from /proc/kmsg we only do the capabilities checks | |
279 | * at open time. | |
280 | */ | |
281 | if (type == SYSLOG_ACTION_OPEN || !from_file) { | |
282 | if (dmesg_restrict && !capable(CAP_SYS_ADMIN)) | |
283 | return -EPERM; | |
284 | if ((type != SYSLOG_ACTION_READ_ALL && | |
285 | type != SYSLOG_ACTION_SIZE_BUFFER) && | |
286 | !capable(CAP_SYS_ADMIN)) | |
287 | return -EPERM; | |
288 | } | |
289 | ||
290 | error = security_syslog(type); | |
1da177e4 LT |
291 | if (error) |
292 | return error; | |
293 | ||
294 | switch (type) { | |
d78ca3cd | 295 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 296 | break; |
d78ca3cd | 297 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 298 | break; |
d78ca3cd | 299 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 LT |
300 | error = -EINVAL; |
301 | if (!buf || len < 0) | |
302 | goto out; | |
303 | error = 0; | |
304 | if (!len) | |
305 | goto out; | |
306 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
307 | error = -EFAULT; | |
308 | goto out; | |
309 | } | |
40dc5651 JJ |
310 | error = wait_event_interruptible(log_wait, |
311 | (log_start - log_end)); | |
1da177e4 LT |
312 | if (error) |
313 | goto out; | |
314 | i = 0; | |
315 | spin_lock_irq(&logbuf_lock); | |
316 | while (!error && (log_start != log_end) && i < len) { | |
317 | c = LOG_BUF(log_start); | |
318 | log_start++; | |
319 | spin_unlock_irq(&logbuf_lock); | |
320 | error = __put_user(c,buf); | |
321 | buf++; | |
322 | i++; | |
323 | cond_resched(); | |
324 | spin_lock_irq(&logbuf_lock); | |
325 | } | |
326 | spin_unlock_irq(&logbuf_lock); | |
327 | if (!error) | |
328 | error = i; | |
329 | break; | |
d78ca3cd KC |
330 | /* Read/clear last kernel messages */ |
331 | case SYSLOG_ACTION_READ_CLEAR: | |
40dc5651 | 332 | do_clear = 1; |
1da177e4 | 333 | /* FALL THRU */ |
d78ca3cd KC |
334 | /* Read last kernel messages */ |
335 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 LT |
336 | error = -EINVAL; |
337 | if (!buf || len < 0) | |
338 | goto out; | |
339 | error = 0; | |
340 | if (!len) | |
341 | goto out; | |
342 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
343 | error = -EFAULT; | |
344 | goto out; | |
345 | } | |
346 | count = len; | |
347 | if (count > log_buf_len) | |
348 | count = log_buf_len; | |
349 | spin_lock_irq(&logbuf_lock); | |
350 | if (count > logged_chars) | |
351 | count = logged_chars; | |
352 | if (do_clear) | |
353 | logged_chars = 0; | |
354 | limit = log_end; | |
355 | /* | |
356 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 357 | * printk() could overwrite the messages |
1da177e4 LT |
358 | * we try to copy to user space. Therefore |
359 | * the messages are copied in reverse. <manfreds> | |
360 | */ | |
40dc5651 | 361 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
362 | j = limit-1-i; |
363 | if (j + log_buf_len < log_end) | |
364 | break; | |
365 | c = LOG_BUF(j); | |
366 | spin_unlock_irq(&logbuf_lock); | |
367 | error = __put_user(c,&buf[count-1-i]); | |
368 | cond_resched(); | |
369 | spin_lock_irq(&logbuf_lock); | |
370 | } | |
371 | spin_unlock_irq(&logbuf_lock); | |
372 | if (error) | |
373 | break; | |
374 | error = i; | |
40dc5651 | 375 | if (i != count) { |
1da177e4 LT |
376 | int offset = count-error; |
377 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 378 | for (i = 0; i < error; i++) { |
1da177e4 LT |
379 | if (__get_user(c,&buf[i+offset]) || |
380 | __put_user(c,&buf[i])) { | |
381 | error = -EFAULT; | |
382 | break; | |
383 | } | |
384 | cond_resched(); | |
385 | } | |
386 | } | |
387 | break; | |
d78ca3cd KC |
388 | /* Clear ring buffer */ |
389 | case SYSLOG_ACTION_CLEAR: | |
1da177e4 LT |
390 | logged_chars = 0; |
391 | break; | |
d78ca3cd KC |
392 | /* Disable logging to console */ |
393 | case SYSLOG_ACTION_CONSOLE_OFF: | |
1aaad49e FP |
394 | if (saved_console_loglevel == -1) |
395 | saved_console_loglevel = console_loglevel; | |
1da177e4 LT |
396 | console_loglevel = minimum_console_loglevel; |
397 | break; | |
d78ca3cd KC |
398 | /* Enable logging to console */ |
399 | case SYSLOG_ACTION_CONSOLE_ON: | |
1aaad49e FP |
400 | if (saved_console_loglevel != -1) { |
401 | console_loglevel = saved_console_loglevel; | |
402 | saved_console_loglevel = -1; | |
403 | } | |
1da177e4 | 404 | break; |
d78ca3cd KC |
405 | /* Set level of messages printed to console */ |
406 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 LT |
407 | error = -EINVAL; |
408 | if (len < 1 || len > 8) | |
409 | goto out; | |
410 | if (len < minimum_console_loglevel) | |
411 | len = minimum_console_loglevel; | |
412 | console_loglevel = len; | |
1aaad49e FP |
413 | /* Implicitly re-enable logging to console */ |
414 | saved_console_loglevel = -1; | |
1da177e4 LT |
415 | error = 0; |
416 | break; | |
d78ca3cd KC |
417 | /* Number of chars in the log buffer */ |
418 | case SYSLOG_ACTION_SIZE_UNREAD: | |
1da177e4 LT |
419 | error = log_end - log_start; |
420 | break; | |
d78ca3cd KC |
421 | /* Size of the log buffer */ |
422 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
423 | error = log_buf_len; |
424 | break; | |
425 | default: | |
426 | error = -EINVAL; | |
427 | break; | |
428 | } | |
429 | out: | |
430 | return error; | |
431 | } | |
432 | ||
1e7bfb21 | 433 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 434 | { |
00234592 | 435 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
1da177e4 LT |
436 | } |
437 | ||
67fc4e0c JW |
438 | #ifdef CONFIG_KGDB_KDB |
439 | /* kdb dmesg command needs access to the syslog buffer. do_syslog() | |
440 | * uses locks so it cannot be used during debugging. Just tell kdb | |
441 | * where the start and end of the physical and logical logs are. This | |
442 | * is equivalent to do_syslog(3). | |
443 | */ | |
444 | void kdb_syslog_data(char *syslog_data[4]) | |
445 | { | |
446 | syslog_data[0] = log_buf; | |
447 | syslog_data[1] = log_buf + log_buf_len; | |
448 | syslog_data[2] = log_buf + log_end - | |
449 | (logged_chars < log_buf_len ? logged_chars : log_buf_len); | |
450 | syslog_data[3] = log_buf + log_end; | |
451 | } | |
452 | #endif /* CONFIG_KGDB_KDB */ | |
453 | ||
1da177e4 LT |
454 | /* |
455 | * Call the console drivers on a range of log_buf | |
456 | */ | |
eed4a2ab | 457 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
458 | { |
459 | struct console *con; | |
460 | ||
4d091611 | 461 | for_each_console(con) { |
76a8ad29 ME |
462 | if ((con->flags & CON_ENABLED) && con->write && |
463 | (cpu_online(smp_processor_id()) || | |
464 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
465 | con->write(con, &LOG_BUF(start), end - start); |
466 | } | |
467 | } | |
468 | ||
79290822 IM |
469 | static int __read_mostly ignore_loglevel; |
470 | ||
99eea6a1 | 471 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
472 | { |
473 | ignore_loglevel = 1; | |
474 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
475 | ||
c4772d99 | 476 | return 0; |
79290822 IM |
477 | } |
478 | ||
c4772d99 | 479 | early_param("ignore_loglevel", ignore_loglevel_setup); |
79290822 | 480 | |
1da177e4 LT |
481 | /* |
482 | * Write out chars from start to end - 1 inclusive | |
483 | */ | |
eed4a2ab DV |
484 | static void _call_console_drivers(unsigned start, |
485 | unsigned end, int msg_log_level) | |
1da177e4 | 486 | { |
79290822 | 487 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
488 | console_drivers && start != end) { |
489 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
490 | /* wrapped write */ | |
491 | __call_console_drivers(start & LOG_BUF_MASK, | |
492 | log_buf_len); | |
493 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
494 | } else { | |
495 | __call_console_drivers(start, end); | |
496 | } | |
497 | } | |
498 | } | |
499 | ||
500 | /* | |
501 | * Call the console drivers, asking them to write out | |
502 | * log_buf[start] to log_buf[end - 1]. | |
503 | * The console_sem must be held. | |
504 | */ | |
eed4a2ab | 505 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 506 | { |
eed4a2ab | 507 | unsigned cur_index, start_print; |
1da177e4 LT |
508 | static int msg_level = -1; |
509 | ||
eed4a2ab | 510 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
511 | |
512 | cur_index = start; | |
513 | start_print = start; | |
514 | while (cur_index != end) { | |
40dc5651 JJ |
515 | if (msg_level < 0 && ((end - cur_index) > 2) && |
516 | LOG_BUF(cur_index + 0) == '<' && | |
517 | LOG_BUF(cur_index + 1) >= '0' && | |
518 | LOG_BUF(cur_index + 1) <= '7' && | |
519 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
520 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
521 | cur_index += 3; | |
522 | start_print = cur_index; | |
523 | } | |
524 | while (cur_index != end) { | |
525 | char c = LOG_BUF(cur_index); | |
1da177e4 | 526 | |
40dc5651 | 527 | cur_index++; |
1da177e4 LT |
528 | if (c == '\n') { |
529 | if (msg_level < 0) { | |
530 | /* | |
531 | * printk() has already given us loglevel tags in | |
532 | * the buffer. This code is here in case the | |
533 | * log buffer has wrapped right round and scribbled | |
534 | * on those tags | |
535 | */ | |
536 | msg_level = default_message_loglevel; | |
537 | } | |
538 | _call_console_drivers(start_print, cur_index, msg_level); | |
539 | msg_level = -1; | |
540 | start_print = cur_index; | |
541 | break; | |
542 | } | |
543 | } | |
544 | } | |
545 | _call_console_drivers(start_print, end, msg_level); | |
546 | } | |
547 | ||
548 | static void emit_log_char(char c) | |
549 | { | |
550 | LOG_BUF(log_end) = c; | |
551 | log_end++; | |
552 | if (log_end - log_start > log_buf_len) | |
553 | log_start = log_end - log_buf_len; | |
554 | if (log_end - con_start > log_buf_len) | |
555 | con_start = log_end - log_buf_len; | |
556 | if (logged_chars < log_buf_len) | |
557 | logged_chars++; | |
558 | } | |
559 | ||
560 | /* | |
561 | * Zap console related locks when oopsing. Only zap at most once | |
562 | * every 10 seconds, to leave time for slow consoles to print a | |
563 | * full oops. | |
564 | */ | |
565 | static void zap_locks(void) | |
566 | { | |
567 | static unsigned long oops_timestamp; | |
568 | ||
569 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 570 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
571 | return; |
572 | ||
573 | oops_timestamp = jiffies; | |
574 | ||
575 | /* If a crash is occurring, make sure we can't deadlock */ | |
576 | spin_lock_init(&logbuf_lock); | |
577 | /* And make sure that we print immediately */ | |
5b8c4f23 | 578 | sema_init(&console_sem, 1); |
1da177e4 LT |
579 | } |
580 | ||
581 | #if defined(CONFIG_PRINTK_TIME) | |
582 | static int printk_time = 1; | |
583 | #else | |
584 | static int printk_time = 0; | |
585 | #endif | |
e84845c4 | 586 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 587 | |
76a8ad29 ME |
588 | /* Check if we have any console registered that can be called early in boot. */ |
589 | static int have_callable_console(void) | |
590 | { | |
591 | struct console *con; | |
592 | ||
4d091611 | 593 | for_each_console(con) |
76a8ad29 ME |
594 | if (con->flags & CON_ANYTIME) |
595 | return 1; | |
596 | ||
597 | return 0; | |
598 | } | |
599 | ||
ddad86c2 MW |
600 | /** |
601 | * printk - print a kernel message | |
602 | * @fmt: format string | |
603 | * | |
72fd4a35 | 604 | * This is printk(). It can be called from any context. We want it to work. |
40dc5651 | 605 | * |
1da177e4 LT |
606 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
607 | * call the console drivers. If we fail to get the semaphore we place the output | |
608 | * into the log buffer and return. The current holder of the console_sem will | |
609 | * notice the new output in release_console_sem() and will send it to the | |
610 | * consoles before releasing the semaphore. | |
611 | * | |
612 | * One effect of this deferred printing is that code which calls printk() and | |
613 | * then changes console_loglevel may break. This is because console_loglevel | |
614 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
615 | * |
616 | * See also: | |
617 | * printf(3) | |
20036fdc AK |
618 | * |
619 | * See the vsnprintf() documentation for format string extensions over C99. | |
1da177e4 | 620 | */ |
d59745ce | 621 | |
1da177e4 LT |
622 | asmlinkage int printk(const char *fmt, ...) |
623 | { | |
624 | va_list args; | |
625 | int r; | |
626 | ||
d37d39ae JW |
627 | #ifdef CONFIG_KGDB_KDB |
628 | if (unlikely(kdb_trap_printk)) { | |
629 | va_start(args, fmt); | |
630 | r = vkdb_printf(fmt, args); | |
631 | va_end(args); | |
632 | return r; | |
633 | } | |
634 | #endif | |
1da177e4 LT |
635 | va_start(args, fmt); |
636 | r = vprintk(fmt, args); | |
637 | va_end(args); | |
638 | ||
639 | return r; | |
640 | } | |
641 | ||
fe21773d DH |
642 | /* cpu currently holding logbuf_lock */ |
643 | static volatile unsigned int printk_cpu = UINT_MAX; | |
644 | ||
266c2e0a LT |
645 | /* |
646 | * Can we actually use the console at this time on this cpu? | |
647 | * | |
648 | * Console drivers may assume that per-cpu resources have | |
649 | * been allocated. So unless they're explicitly marked as | |
650 | * being able to cope (CON_ANYTIME) don't call them until | |
651 | * this CPU is officially up. | |
652 | */ | |
653 | static inline int can_use_console(unsigned int cpu) | |
654 | { | |
655 | return cpu_online(cpu) || have_callable_console(); | |
656 | } | |
657 | ||
658 | /* | |
659 | * Try to get console ownership to actually show the kernel | |
660 | * messages from a 'printk'. Return true (and with the | |
661 | * console_semaphore held, and 'console_locked' set) if it | |
662 | * is successful, false otherwise. | |
663 | * | |
664 | * This gets called with the 'logbuf_lock' spinlock held and | |
665 | * interrupts disabled. It should return with 'lockbuf_lock' | |
666 | * released but interrupts still disabled. | |
667 | */ | |
668 | static int acquire_console_semaphore_for_printk(unsigned int cpu) | |
8155c02a | 669 | __releases(&logbuf_lock) |
266c2e0a LT |
670 | { |
671 | int retval = 0; | |
672 | ||
093a07e2 LT |
673 | if (!try_acquire_console_sem()) { |
674 | retval = 1; | |
675 | ||
676 | /* | |
677 | * If we can't use the console, we need to release | |
678 | * the console semaphore by hand to avoid flushing | |
679 | * the buffer. We need to hold the console semaphore | |
680 | * in order to do this test safely. | |
681 | */ | |
682 | if (!can_use_console(cpu)) { | |
683 | console_locked = 0; | |
684 | up(&console_sem); | |
685 | retval = 0; | |
686 | } | |
687 | } | |
266c2e0a LT |
688 | printk_cpu = UINT_MAX; |
689 | spin_unlock(&logbuf_lock); | |
690 | return retval; | |
691 | } | |
3b8945e8 TH |
692 | static const char recursion_bug_msg [] = |
693 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
694 | static int recursion_bug; | |
edb123e1 | 695 | static int new_text_line = 1; |
3b8945e8 | 696 | static char printk_buf[1024]; |
32a76006 | 697 | |
af91322e DY |
698 | int printk_delay_msec __read_mostly; |
699 | ||
700 | static inline void printk_delay(void) | |
701 | { | |
702 | if (unlikely(printk_delay_msec)) { | |
703 | int m = printk_delay_msec; | |
704 | ||
705 | while (m--) { | |
706 | mdelay(1); | |
707 | touch_nmi_watchdog(); | |
708 | } | |
709 | } | |
710 | } | |
711 | ||
1da177e4 LT |
712 | asmlinkage int vprintk(const char *fmt, va_list args) |
713 | { | |
32a76006 | 714 | int printed_len = 0; |
09159308 | 715 | int current_log_level = default_message_loglevel; |
ac60ad74 | 716 | unsigned long flags; |
32a76006 | 717 | int this_cpu; |
1da177e4 | 718 | char *p; |
1da177e4 | 719 | |
bfe8df3d | 720 | boot_delay_msec(); |
af91322e | 721 | printk_delay(); |
bfe8df3d | 722 | |
fe21773d | 723 | preempt_disable(); |
1da177e4 | 724 | /* This stops the holder of console_sem just where we want him */ |
1efc5da3 | 725 | raw_local_irq_save(flags); |
32a76006 IM |
726 | this_cpu = smp_processor_id(); |
727 | ||
728 | /* | |
729 | * Ouch, printk recursed into itself! | |
730 | */ | |
731 | if (unlikely(printk_cpu == this_cpu)) { | |
732 | /* | |
733 | * If a crash is occurring during printk() on this CPU, | |
734 | * then try to get the crash message out but make sure | |
735 | * we can't deadlock. Otherwise just return to avoid the | |
736 | * recursion and return - but flag the recursion so that | |
737 | * it can be printed at the next appropriate moment: | |
738 | */ | |
739 | if (!oops_in_progress) { | |
3b8945e8 | 740 | recursion_bug = 1; |
32a76006 IM |
741 | goto out_restore_irqs; |
742 | } | |
743 | zap_locks(); | |
744 | } | |
745 | ||
a0f1ccfd IM |
746 | lockdep_off(); |
747 | spin_lock(&logbuf_lock); | |
32a76006 | 748 | printk_cpu = this_cpu; |
1da177e4 | 749 | |
3b8945e8 TH |
750 | if (recursion_bug) { |
751 | recursion_bug = 0; | |
752 | strcpy(printk_buf, recursion_bug_msg); | |
26cc271d | 753 | printed_len = strlen(recursion_bug_msg); |
32a76006 | 754 | } |
1da177e4 | 755 | /* Emit the output into the temporary buffer */ |
32a76006 | 756 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 757 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 758 | |
ac60ad74 | 759 | |
5fd29d6c LT |
760 | p = printk_buf; |
761 | ||
762 | /* Do we have a loglevel in the string? */ | |
763 | if (p[0] == '<') { | |
764 | unsigned char c = p[1]; | |
765 | if (c && p[2] == '>') { | |
766 | switch (c) { | |
767 | case '0' ... '7': /* loglevel */ | |
768 | current_log_level = c - '0'; | |
e28d7137 LT |
769 | /* Fallthrough - make sure we're on a new line */ |
770 | case 'd': /* KERN_DEFAULT */ | |
5fd29d6c LT |
771 | if (!new_text_line) { |
772 | emit_log_char('\n'); | |
773 | new_text_line = 1; | |
774 | } | |
775 | /* Fallthrough - skip the loglevel */ | |
776 | case 'c': /* KERN_CONT */ | |
777 | p += 3; | |
778 | break; | |
779 | } | |
780 | } | |
781 | } | |
782 | ||
1da177e4 LT |
783 | /* |
784 | * Copy the output into log_buf. If the caller didn't provide | |
785 | * appropriate log level tags, we insert them here | |
786 | */ | |
5fd29d6c | 787 | for ( ; *p; p++) { |
ac60ad74 | 788 | if (new_text_line) { |
ac60ad74 NA |
789 | /* Always output the token */ |
790 | emit_log_char('<'); | |
791 | emit_log_char(current_log_level + '0'); | |
792 | emit_log_char('>'); | |
793 | printed_len += 3; | |
794 | new_text_line = 0; | |
795 | ||
1da177e4 | 796 | if (printk_time) { |
ac60ad74 | 797 | /* Follow the token with the time */ |
1da177e4 LT |
798 | char tbuf[50], *tp; |
799 | unsigned tlen; | |
800 | unsigned long long t; | |
801 | unsigned long nanosec_rem; | |
802 | ||
326e96b9 | 803 | t = cpu_clock(printk_cpu); |
1da177e4 | 804 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
805 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
806 | (unsigned long) t, | |
807 | nanosec_rem / 1000); | |
1da177e4 LT |
808 | |
809 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
810 | emit_log_char(*tp); | |
025510cd | 811 | printed_len += tlen; |
1da177e4 | 812 | } |
ac60ad74 | 813 | |
1da177e4 LT |
814 | if (!*p) |
815 | break; | |
816 | } | |
ac60ad74 | 817 | |
1da177e4 LT |
818 | emit_log_char(*p); |
819 | if (*p == '\n') | |
ac60ad74 | 820 | new_text_line = 1; |
1da177e4 LT |
821 | } |
822 | ||
266c2e0a LT |
823 | /* |
824 | * Try to acquire and then immediately release the | |
825 | * console semaphore. The release will do all the | |
826 | * actual magic (print out buffers, wake up klogd, | |
827 | * etc). | |
828 | * | |
829 | * The acquire_console_semaphore_for_printk() function | |
830 | * will release 'logbuf_lock' regardless of whether it | |
831 | * actually gets the semaphore or not. | |
832 | */ | |
833 | if (acquire_console_semaphore_for_printk(this_cpu)) | |
834 | release_console_sem(); | |
76a8ad29 | 835 | |
266c2e0a | 836 | lockdep_on(); |
32a76006 | 837 | out_restore_irqs: |
266c2e0a | 838 | raw_local_irq_restore(flags); |
76a8ad29 | 839 | |
fe21773d | 840 | preempt_enable(); |
1da177e4 LT |
841 | return printed_len; |
842 | } | |
843 | EXPORT_SYMBOL(printk); | |
844 | EXPORT_SYMBOL(vprintk); | |
845 | ||
d59745ce MM |
846 | #else |
847 | ||
eed4a2ab | 848 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
849 | { |
850 | } | |
d59745ce MM |
851 | |
852 | #endif | |
853 | ||
f7511d5f ST |
854 | static int __add_preferred_console(char *name, int idx, char *options, |
855 | char *brl_options) | |
856 | { | |
857 | struct console_cmdline *c; | |
858 | int i; | |
859 | ||
860 | /* | |
861 | * See if this tty is not yet registered, and | |
862 | * if we have a slot free. | |
863 | */ | |
864 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
865 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
866 | console_cmdline[i].index == idx) { | |
867 | if (!brl_options) | |
868 | selected_console = i; | |
869 | return 0; | |
870 | } | |
871 | if (i == MAX_CMDLINECONSOLES) | |
872 | return -E2BIG; | |
873 | if (!brl_options) | |
874 | selected_console = i; | |
875 | c = &console_cmdline[i]; | |
876 | strlcpy(c->name, name, sizeof(c->name)); | |
877 | c->options = options; | |
878 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
879 | c->brl_options = brl_options; | |
880 | #endif | |
881 | c->index = idx; | |
882 | return 0; | |
883 | } | |
2ea1c539 JB |
884 | /* |
885 | * Set up a list of consoles. Called from init/main.c | |
886 | */ | |
887 | static int __init console_setup(char *str) | |
888 | { | |
eaa944af | 889 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 890 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
891 | int idx; |
892 | ||
f7511d5f ST |
893 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
894 | if (!memcmp(str, "brl,", 4)) { | |
895 | brl_options = ""; | |
896 | str += 4; | |
897 | } else if (!memcmp(str, "brl=", 4)) { | |
898 | brl_options = str + 4; | |
899 | str = strchr(brl_options, ','); | |
900 | if (!str) { | |
901 | printk(KERN_ERR "need port name after brl=\n"); | |
902 | return 1; | |
903 | } | |
904 | *(str++) = 0; | |
905 | } | |
906 | #endif | |
907 | ||
2ea1c539 JB |
908 | /* |
909 | * Decode str into name, index, options. | |
910 | */ | |
911 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
912 | strcpy(buf, "ttyS"); |
913 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 914 | } else { |
eaa944af | 915 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 916 | } |
eaa944af | 917 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
918 | if ((options = strchr(str, ',')) != NULL) |
919 | *(options++) = 0; | |
920 | #ifdef __sparc__ | |
921 | if (!strcmp(str, "ttya")) | |
eaa944af | 922 | strcpy(buf, "ttyS0"); |
2ea1c539 | 923 | if (!strcmp(str, "ttyb")) |
eaa944af | 924 | strcpy(buf, "ttyS1"); |
2ea1c539 | 925 | #endif |
eaa944af | 926 | for (s = buf; *s; s++) |
2ea1c539 JB |
927 | if ((*s >= '0' && *s <= '9') || *s == ',') |
928 | break; | |
929 | idx = simple_strtoul(s, NULL, 10); | |
930 | *s = 0; | |
931 | ||
f7511d5f | 932 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 933 | console_set_on_cmdline = 1; |
2ea1c539 JB |
934 | return 1; |
935 | } | |
936 | __setup("console=", console_setup); | |
937 | ||
3c0547ba MM |
938 | /** |
939 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
940 | * @name: device name |
941 | * @idx: device index | |
942 | * @options: options for this console | |
3c0547ba MM |
943 | * |
944 | * The last preferred console added will be used for kernel messages | |
945 | * and stdin/out/err for init. Normally this is used by console_setup | |
946 | * above to handle user-supplied console arguments; however it can also | |
947 | * be used by arch-specific code either to override the user or more | |
948 | * commonly to provide a default console (ie from PROM variables) when | |
949 | * the user has not supplied one. | |
950 | */ | |
fb445ee5 | 951 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 952 | { |
f7511d5f | 953 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
954 | } |
955 | ||
b6b1d877 | 956 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
957 | { |
958 | struct console_cmdline *c; | |
959 | int i; | |
960 | ||
961 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
962 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
963 | console_cmdline[i].index == idx) { | |
964 | c = &console_cmdline[i]; | |
f735295b | 965 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
966 | c->name[sizeof(c->name) - 1] = 0; |
967 | c->options = options; | |
968 | c->index = idx_new; | |
969 | return i; | |
970 | } | |
971 | /* not found */ | |
972 | return -1; | |
973 | } | |
974 | ||
8f4ce8c3 AS |
975 | int console_suspend_enabled = 1; |
976 | EXPORT_SYMBOL(console_suspend_enabled); | |
977 | ||
978 | static int __init console_suspend_disable(char *str) | |
979 | { | |
980 | console_suspend_enabled = 0; | |
981 | return 1; | |
982 | } | |
983 | __setup("no_console_suspend", console_suspend_disable); | |
984 | ||
557240b4 LT |
985 | /** |
986 | * suspend_console - suspend the console subsystem | |
987 | * | |
988 | * This disables printk() while we go into suspend states | |
989 | */ | |
990 | void suspend_console(void) | |
991 | { | |
8f4ce8c3 AS |
992 | if (!console_suspend_enabled) |
993 | return; | |
0d63081d | 994 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
557240b4 LT |
995 | acquire_console_sem(); |
996 | console_suspended = 1; | |
403f3075 | 997 | up(&console_sem); |
557240b4 LT |
998 | } |
999 | ||
1000 | void resume_console(void) | |
1001 | { | |
8f4ce8c3 AS |
1002 | if (!console_suspend_enabled) |
1003 | return; | |
403f3075 | 1004 | down(&console_sem); |
557240b4 LT |
1005 | console_suspended = 0; |
1006 | release_console_sem(); | |
1007 | } | |
1008 | ||
034260d6 KC |
1009 | /** |
1010 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
1011 | * @self: notifier struct | |
1012 | * @action: CPU hotplug event | |
1013 | * @hcpu: unused | |
1014 | * | |
1015 | * If printk() is called from a CPU that is not online yet, the messages | |
1016 | * will be spooled but will not show up on the console. This function is | |
1017 | * called when a new CPU comes online (or fails to come up), and ensures | |
1018 | * that any such output gets printed. | |
1019 | */ | |
1020 | static int __cpuinit console_cpu_notify(struct notifier_block *self, | |
1021 | unsigned long action, void *hcpu) | |
1022 | { | |
1023 | switch (action) { | |
1024 | case CPU_ONLINE: | |
1025 | case CPU_DEAD: | |
1026 | case CPU_DYING: | |
1027 | case CPU_DOWN_FAILED: | |
1028 | case CPU_UP_CANCELED: | |
1029 | acquire_console_sem(); | |
1030 | release_console_sem(); | |
1031 | } | |
1032 | return NOTIFY_OK; | |
1033 | } | |
1034 | ||
1da177e4 LT |
1035 | /** |
1036 | * acquire_console_sem - lock the console system for exclusive use. | |
1037 | * | |
1038 | * Acquires a semaphore which guarantees that the caller has | |
1039 | * exclusive access to the console system and the console_drivers list. | |
1040 | * | |
1041 | * Can sleep, returns nothing. | |
1042 | */ | |
1043 | void acquire_console_sem(void) | |
1044 | { | |
8abd8e29 | 1045 | BUG_ON(in_interrupt()); |
1da177e4 | 1046 | down(&console_sem); |
403f3075 AH |
1047 | if (console_suspended) |
1048 | return; | |
1da177e4 LT |
1049 | console_locked = 1; |
1050 | console_may_schedule = 1; | |
1051 | } | |
1052 | EXPORT_SYMBOL(acquire_console_sem); | |
1053 | ||
1054 | int try_acquire_console_sem(void) | |
1055 | { | |
1056 | if (down_trylock(&console_sem)) | |
1057 | return -1; | |
403f3075 AH |
1058 | if (console_suspended) { |
1059 | up(&console_sem); | |
1060 | return -1; | |
1061 | } | |
1da177e4 LT |
1062 | console_locked = 1; |
1063 | console_may_schedule = 0; | |
1064 | return 0; | |
1065 | } | |
1066 | EXPORT_SYMBOL(try_acquire_console_sem); | |
1067 | ||
1068 | int is_console_locked(void) | |
1069 | { | |
1070 | return console_locked; | |
1071 | } | |
1da177e4 | 1072 | |
b845b517 PZ |
1073 | static DEFINE_PER_CPU(int, printk_pending); |
1074 | ||
1075 | void printk_tick(void) | |
e3e8a75d | 1076 | { |
b845b517 PZ |
1077 | if (__get_cpu_var(printk_pending)) { |
1078 | __get_cpu_var(printk_pending) = 0; | |
e3e8a75d | 1079 | wake_up_interruptible(&log_wait); |
b845b517 PZ |
1080 | } |
1081 | } | |
1082 | ||
1083 | int printk_needs_cpu(int cpu) | |
1084 | { | |
61ab2544 HC |
1085 | if (unlikely(cpu_is_offline(cpu))) |
1086 | printk_tick(); | |
b845b517 PZ |
1087 | return per_cpu(printk_pending, cpu); |
1088 | } | |
1089 | ||
1090 | void wake_up_klogd(void) | |
1091 | { | |
1092 | if (waitqueue_active(&log_wait)) | |
49f41383 | 1093 | this_cpu_write(printk_pending, 1); |
e3e8a75d KK |
1094 | } |
1095 | ||
1da177e4 LT |
1096 | /** |
1097 | * release_console_sem - unlock the console system | |
1098 | * | |
1099 | * Releases the semaphore which the caller holds on the console system | |
1100 | * and the console driver list. | |
1101 | * | |
1102 | * While the semaphore was held, console output may have been buffered | |
1103 | * by printk(). If this is the case, release_console_sem() emits | |
1104 | * the output prior to releasing the semaphore. | |
1105 | * | |
1106 | * If there is output waiting for klogd, we wake it up. | |
1107 | * | |
1108 | * release_console_sem() may be called from any context. | |
1109 | */ | |
1110 | void release_console_sem(void) | |
1111 | { | |
1112 | unsigned long flags; | |
eed4a2ab DV |
1113 | unsigned _con_start, _log_end; |
1114 | unsigned wake_klogd = 0; | |
1da177e4 | 1115 | |
557240b4 | 1116 | if (console_suspended) { |
403f3075 | 1117 | up(&console_sem); |
557240b4 LT |
1118 | return; |
1119 | } | |
78944e54 AD |
1120 | |
1121 | console_may_schedule = 0; | |
1122 | ||
1da177e4 LT |
1123 | for ( ; ; ) { |
1124 | spin_lock_irqsave(&logbuf_lock, flags); | |
1125 | wake_klogd |= log_start - log_end; | |
1126 | if (con_start == log_end) | |
1127 | break; /* Nothing to print */ | |
1128 | _con_start = con_start; | |
1129 | _log_end = log_end; | |
1130 | con_start = log_end; /* Flush */ | |
1131 | spin_unlock(&logbuf_lock); | |
81d68a96 | 1132 | stop_critical_timings(); /* don't trace print latency */ |
1da177e4 | 1133 | call_console_drivers(_con_start, _log_end); |
81d68a96 | 1134 | start_critical_timings(); |
1da177e4 LT |
1135 | local_irq_restore(flags); |
1136 | } | |
1137 | console_locked = 0; | |
1da177e4 LT |
1138 | up(&console_sem); |
1139 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
1140 | if (wake_klogd) |
1141 | wake_up_klogd(); | |
1da177e4 LT |
1142 | } |
1143 | EXPORT_SYMBOL(release_console_sem); | |
1144 | ||
ddad86c2 MW |
1145 | /** |
1146 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1147 | * |
1148 | * If the console code is currently allowed to sleep, and | |
1149 | * if this CPU should yield the CPU to another task, do | |
1150 | * so here. | |
1151 | * | |
1152 | * Must be called within acquire_console_sem(). | |
1153 | */ | |
1154 | void __sched console_conditional_schedule(void) | |
1155 | { | |
1156 | if (console_may_schedule) | |
1157 | cond_resched(); | |
1158 | } | |
1159 | EXPORT_SYMBOL(console_conditional_schedule); | |
1160 | ||
1da177e4 LT |
1161 | void console_unblank(void) |
1162 | { | |
1163 | struct console *c; | |
1164 | ||
1165 | /* | |
1166 | * console_unblank can no longer be called in interrupt context unless | |
1167 | * oops_in_progress is set to 1.. | |
1168 | */ | |
1169 | if (oops_in_progress) { | |
1170 | if (down_trylock(&console_sem) != 0) | |
1171 | return; | |
1172 | } else | |
1173 | acquire_console_sem(); | |
1174 | ||
1175 | console_locked = 1; | |
1176 | console_may_schedule = 0; | |
4d091611 | 1177 | for_each_console(c) |
1da177e4 LT |
1178 | if ((c->flags & CON_ENABLED) && c->unblank) |
1179 | c->unblank(); | |
1180 | release_console_sem(); | |
1181 | } | |
1da177e4 LT |
1182 | |
1183 | /* | |
1184 | * Return the console tty driver structure and its associated index | |
1185 | */ | |
1186 | struct tty_driver *console_device(int *index) | |
1187 | { | |
1188 | struct console *c; | |
1189 | struct tty_driver *driver = NULL; | |
1190 | ||
1191 | acquire_console_sem(); | |
4d091611 | 1192 | for_each_console(c) { |
1da177e4 LT |
1193 | if (!c->device) |
1194 | continue; | |
1195 | driver = c->device(c, index); | |
1196 | if (driver) | |
1197 | break; | |
1198 | } | |
1199 | release_console_sem(); | |
1200 | return driver; | |
1201 | } | |
1202 | ||
1203 | /* | |
1204 | * Prevent further output on the passed console device so that (for example) | |
1205 | * serial drivers can disable console output before suspending a port, and can | |
1206 | * re-enable output afterwards. | |
1207 | */ | |
1208 | void console_stop(struct console *console) | |
1209 | { | |
1210 | acquire_console_sem(); | |
1211 | console->flags &= ~CON_ENABLED; | |
1212 | release_console_sem(); | |
1213 | } | |
1214 | EXPORT_SYMBOL(console_stop); | |
1215 | ||
1216 | void console_start(struct console *console) | |
1217 | { | |
1218 | acquire_console_sem(); | |
1219 | console->flags |= CON_ENABLED; | |
1220 | release_console_sem(); | |
1221 | } | |
1222 | EXPORT_SYMBOL(console_start); | |
1223 | ||
1224 | /* | |
1225 | * The console driver calls this routine during kernel initialization | |
1226 | * to register the console printing procedure with printk() and to | |
1227 | * print any messages that were printed by the kernel before the | |
1228 | * console driver was initialized. | |
4d091611 RG |
1229 | * |
1230 | * This can happen pretty early during the boot process (because of | |
1231 | * early_printk) - sometimes before setup_arch() completes - be careful | |
1232 | * of what kernel features are used - they may not be initialised yet. | |
1233 | * | |
1234 | * There are two types of consoles - bootconsoles (early_printk) and | |
1235 | * "real" consoles (everything which is not a bootconsole) which are | |
1236 | * handled differently. | |
1237 | * - Any number of bootconsoles can be registered at any time. | |
1238 | * - As soon as a "real" console is registered, all bootconsoles | |
1239 | * will be unregistered automatically. | |
1240 | * - Once a "real" console is registered, any attempt to register a | |
1241 | * bootconsoles will be rejected | |
1da177e4 | 1242 | */ |
4d091611 | 1243 | void register_console(struct console *newcon) |
1da177e4 | 1244 | { |
40dc5651 | 1245 | int i; |
1da177e4 | 1246 | unsigned long flags; |
4d091611 | 1247 | struct console *bcon = NULL; |
1da177e4 | 1248 | |
4d091611 RG |
1249 | /* |
1250 | * before we register a new CON_BOOT console, make sure we don't | |
1251 | * already have a valid console | |
1252 | */ | |
1253 | if (console_drivers && newcon->flags & CON_BOOT) { | |
1254 | /* find the last or real console */ | |
1255 | for_each_console(bcon) { | |
1256 | if (!(bcon->flags & CON_BOOT)) { | |
1257 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", | |
1258 | newcon->name, newcon->index); | |
1259 | return; | |
1260 | } | |
1261 | } | |
69331af7 GH |
1262 | } |
1263 | ||
4d091611 RG |
1264 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1265 | bcon = console_drivers; | |
1266 | ||
1267 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
1268 | preferred_console = selected_console; |
1269 | ||
4d091611 RG |
1270 | if (newcon->early_setup) |
1271 | newcon->early_setup(); | |
18a8bd94 | 1272 | |
1da177e4 LT |
1273 | /* |
1274 | * See if we want to use this console driver. If we | |
1275 | * didn't select a console we take the first one | |
1276 | * that registers here. | |
1277 | */ | |
1278 | if (preferred_console < 0) { | |
4d091611 RG |
1279 | if (newcon->index < 0) |
1280 | newcon->index = 0; | |
1281 | if (newcon->setup == NULL || | |
1282 | newcon->setup(newcon, NULL) == 0) { | |
1283 | newcon->flags |= CON_ENABLED; | |
1284 | if (newcon->device) { | |
1285 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
1286 | preferred_console = 0; |
1287 | } | |
1da177e4 LT |
1288 | } |
1289 | } | |
1290 | ||
1291 | /* | |
1292 | * See if this console matches one we selected on | |
1293 | * the command line. | |
1294 | */ | |
40dc5651 JJ |
1295 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1296 | i++) { | |
4d091611 | 1297 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1da177e4 | 1298 | continue; |
4d091611 RG |
1299 | if (newcon->index >= 0 && |
1300 | newcon->index != console_cmdline[i].index) | |
1da177e4 | 1301 | continue; |
4d091611 RG |
1302 | if (newcon->index < 0) |
1303 | newcon->index = console_cmdline[i].index; | |
f7511d5f ST |
1304 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1305 | if (console_cmdline[i].brl_options) { | |
4d091611 RG |
1306 | newcon->flags |= CON_BRL; |
1307 | braille_register_console(newcon, | |
f7511d5f ST |
1308 | console_cmdline[i].index, |
1309 | console_cmdline[i].options, | |
1310 | console_cmdline[i].brl_options); | |
1311 | return; | |
1312 | } | |
1313 | #endif | |
4d091611 RG |
1314 | if (newcon->setup && |
1315 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 1316 | break; |
4d091611 RG |
1317 | newcon->flags |= CON_ENABLED; |
1318 | newcon->index = console_cmdline[i].index; | |
ab4af03a | 1319 | if (i == selected_console) { |
4d091611 | 1320 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
1321 | preferred_console = selected_console; |
1322 | } | |
1da177e4 LT |
1323 | break; |
1324 | } | |
1325 | ||
4d091611 | 1326 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
1327 | return; |
1328 | ||
8259cf43 RG |
1329 | /* |
1330 | * If we have a bootconsole, and are switching to a real console, | |
1331 | * don't print everything out again, since when the boot console, and | |
1332 | * the real console are the same physical device, it's annoying to | |
1333 | * see the beginning boot messages twice | |
1334 | */ | |
1335 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 1336 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
1337 | |
1338 | /* | |
1339 | * Put this console in the list - keep the | |
1340 | * preferred driver at the head of the list. | |
1341 | */ | |
1342 | acquire_console_sem(); | |
4d091611 RG |
1343 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1344 | newcon->next = console_drivers; | |
1345 | console_drivers = newcon; | |
1346 | if (newcon->next) | |
1347 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 1348 | } else { |
4d091611 RG |
1349 | newcon->next = console_drivers->next; |
1350 | console_drivers->next = newcon; | |
1da177e4 | 1351 | } |
4d091611 | 1352 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 LT |
1353 | /* |
1354 | * release_console_sem() will print out the buffered messages | |
1355 | * for us. | |
1356 | */ | |
1357 | spin_lock_irqsave(&logbuf_lock, flags); | |
1358 | con_start = log_start; | |
1359 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1360 | } | |
1361 | release_console_sem(); | |
8259cf43 RG |
1362 | |
1363 | /* | |
1364 | * By unregistering the bootconsoles after we enable the real console | |
1365 | * we get the "console xxx enabled" message on all the consoles - | |
1366 | * boot consoles, real consoles, etc - this is to ensure that end | |
1367 | * users know there might be something in the kernel's log buffer that | |
1368 | * went to the bootconsole (that they do not see on the real console) | |
1369 | */ | |
1370 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) { | |
1371 | /* we need to iterate through twice, to make sure we print | |
1372 | * everything out, before we unregister the console(s) | |
1373 | */ | |
1374 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", | |
1375 | newcon->name, newcon->index); | |
1376 | for_each_console(bcon) | |
1377 | if (bcon->flags & CON_BOOT) | |
1378 | unregister_console(bcon); | |
1379 | } else { | |
1380 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", | |
1381 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
1382 | newcon->name, newcon->index); | |
1383 | } | |
1da177e4 LT |
1384 | } |
1385 | EXPORT_SYMBOL(register_console); | |
1386 | ||
40dc5651 | 1387 | int unregister_console(struct console *console) |
1da177e4 | 1388 | { |
40dc5651 | 1389 | struct console *a, *b; |
1da177e4 LT |
1390 | int res = 1; |
1391 | ||
f7511d5f ST |
1392 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1393 | if (console->flags & CON_BRL) | |
1394 | return braille_unregister_console(console); | |
1395 | #endif | |
1396 | ||
1da177e4 LT |
1397 | acquire_console_sem(); |
1398 | if (console_drivers == console) { | |
1399 | console_drivers=console->next; | |
1400 | res = 0; | |
e9b15b54 | 1401 | } else if (console_drivers) { |
1da177e4 LT |
1402 | for (a=console_drivers->next, b=console_drivers ; |
1403 | a; b=a, a=b->next) { | |
1404 | if (a == console) { | |
1405 | b->next = a->next; | |
1406 | res = 0; | |
1407 | break; | |
40dc5651 | 1408 | } |
1da177e4 LT |
1409 | } |
1410 | } | |
40dc5651 | 1411 | |
69331af7 | 1412 | /* |
ab4af03a GE |
1413 | * If this isn't the last console and it has CON_CONSDEV set, we |
1414 | * need to set it on the next preferred console. | |
1da177e4 | 1415 | */ |
69331af7 | 1416 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1417 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 LT |
1418 | |
1419 | release_console_sem(); | |
1420 | return res; | |
1421 | } | |
1422 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1423 | |
034260d6 | 1424 | static int __init printk_late_init(void) |
0c5564bd | 1425 | { |
4d091611 RG |
1426 | struct console *con; |
1427 | ||
1428 | for_each_console(con) { | |
1429 | if (con->flags & CON_BOOT) { | |
cb00e99c | 1430 | printk(KERN_INFO "turn off boot console %s%d\n", |
4d091611 | 1431 | con->name, con->index); |
42c2c8c8 | 1432 | unregister_console(con); |
cb00e99c | 1433 | } |
0c5564bd | 1434 | } |
034260d6 | 1435 | hotcpu_notifier(console_cpu_notify, 0); |
0c5564bd RG |
1436 | return 0; |
1437 | } | |
034260d6 | 1438 | late_initcall(printk_late_init); |
0c5564bd | 1439 | |
7ef3d2fd | 1440 | #if defined CONFIG_PRINTK |
717115e1 | 1441 | |
1da177e4 LT |
1442 | /* |
1443 | * printk rate limiting, lifted from the networking subsystem. | |
1444 | * | |
641de9d8 UKK |
1445 | * This enforces a rate limit: not more than 10 kernel messages |
1446 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 1447 | */ |
641de9d8 UKK |
1448 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1449 | ||
5c828713 | 1450 | int __printk_ratelimit(const char *func) |
1da177e4 | 1451 | { |
5c828713 | 1452 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 1453 | } |
5c828713 | 1454 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
1455 | |
1456 | /** | |
1457 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1458 | * @caller_jiffies: pointer to caller's state | |
1459 | * @interval_msecs: minimum interval between prints | |
1460 | * | |
1461 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1462 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1463 | * returned true. | |
1464 | */ | |
1465 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1466 | unsigned int interval_msecs) | |
1467 | { | |
f2d28a2e GK |
1468 | if (*caller_jiffies == 0 |
1469 | || !time_in_range(jiffies, *caller_jiffies, | |
1470 | *caller_jiffies | |
1471 | + msecs_to_jiffies(interval_msecs))) { | |
1472 | *caller_jiffies = jiffies; | |
f46c4833 AM |
1473 | return true; |
1474 | } | |
1475 | return false; | |
1476 | } | |
1477 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
1478 | |
1479 | static DEFINE_SPINLOCK(dump_list_lock); | |
1480 | static LIST_HEAD(dump_list); | |
1481 | ||
1482 | /** | |
1483 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 1484 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1485 | * |
1486 | * Adds a kernel log dumper to the system. The dump callback in the | |
1487 | * structure will be called when the kernel oopses or panics and must be | |
1488 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
1489 | */ | |
1490 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
1491 | { | |
1492 | unsigned long flags; | |
1493 | int err = -EBUSY; | |
1494 | ||
1495 | /* The dump callback needs to be set */ | |
1496 | if (!dumper->dump) | |
1497 | return -EINVAL; | |
1498 | ||
1499 | spin_lock_irqsave(&dump_list_lock, flags); | |
1500 | /* Don't allow registering multiple times */ | |
1501 | if (!dumper->registered) { | |
1502 | dumper->registered = 1; | |
1503 | list_add_tail(&dumper->list, &dump_list); | |
1504 | err = 0; | |
1505 | } | |
1506 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1507 | ||
1508 | return err; | |
1509 | } | |
1510 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
1511 | ||
1512 | /** | |
1513 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 1514 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1515 | * |
1516 | * Removes a dump device from the system. Returns zero on success and | |
1517 | * %-EINVAL otherwise. | |
1518 | */ | |
1519 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
1520 | { | |
1521 | unsigned long flags; | |
1522 | int err = -EINVAL; | |
1523 | ||
1524 | spin_lock_irqsave(&dump_list_lock, flags); | |
1525 | if (dumper->registered) { | |
1526 | dumper->registered = 0; | |
1527 | list_del(&dumper->list); | |
1528 | err = 0; | |
1529 | } | |
1530 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1531 | ||
1532 | return err; | |
1533 | } | |
1534 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
1535 | ||
6c095efd | 1536 | static const char * const kmsg_reasons[] = { |
456b565c SK |
1537 | [KMSG_DUMP_OOPS] = "oops", |
1538 | [KMSG_DUMP_PANIC] = "panic", | |
0f4bd46e | 1539 | [KMSG_DUMP_KEXEC] = "kexec", |
456b565c SK |
1540 | }; |
1541 | ||
1542 | static const char *kmsg_to_str(enum kmsg_dump_reason reason) | |
1543 | { | |
1544 | if (reason >= ARRAY_SIZE(kmsg_reasons) || reason < 0) | |
1545 | return "unknown"; | |
1546 | ||
1547 | return kmsg_reasons[reason]; | |
1548 | } | |
1549 | ||
1550 | /** | |
1551 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
1552 | * @reason: the reason (oops, panic etc) for dumping | |
1553 | * | |
1554 | * Iterate through each of the dump devices and call the oops/panic | |
1555 | * callbacks with the log buffer. | |
1556 | */ | |
1557 | void kmsg_dump(enum kmsg_dump_reason reason) | |
1558 | { | |
1559 | unsigned long end; | |
1560 | unsigned chars; | |
1561 | struct kmsg_dumper *dumper; | |
1562 | const char *s1, *s2; | |
1563 | unsigned long l1, l2; | |
1564 | unsigned long flags; | |
1565 | ||
1566 | /* Theoretically, the log could move on after we do this, but | |
1567 | there's not a lot we can do about that. The new messages | |
1568 | will overwrite the start of what we dump. */ | |
1569 | spin_lock_irqsave(&logbuf_lock, flags); | |
1570 | end = log_end & LOG_BUF_MASK; | |
1571 | chars = logged_chars; | |
1572 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1573 | ||
8c4af38e AK |
1574 | if (chars > end) { |
1575 | s1 = log_buf + log_buf_len - chars + end; | |
1576 | l1 = chars - end; | |
456b565c SK |
1577 | |
1578 | s2 = log_buf; | |
1579 | l2 = end; | |
1580 | } else { | |
1581 | s1 = ""; | |
1582 | l1 = 0; | |
1583 | ||
8c4af38e AK |
1584 | s2 = log_buf + end - chars; |
1585 | l2 = chars; | |
456b565c SK |
1586 | } |
1587 | ||
1588 | if (!spin_trylock_irqsave(&dump_list_lock, flags)) { | |
1589 | printk(KERN_ERR "dump_kmsg: dump list lock is held during %s, skipping dump\n", | |
1590 | kmsg_to_str(reason)); | |
1591 | return; | |
1592 | } | |
1593 | list_for_each_entry(dumper, &dump_list, list) | |
1594 | dumper->dump(dumper, reason, s1, l1, s2, l2); | |
1595 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1596 | } | |
7ef3d2fd | 1597 | #endif |