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> |
3fff4c42 | 36 | #include <linux/ratelimit.h> |
456b565c | 37 | #include <linux/kmsg_dump.h> |
00234592 | 38 | #include <linux/syslog.h> |
1da177e4 LT |
39 | |
40 | #include <asm/uaccess.h> | |
41 | ||
4d091611 RG |
42 | /* |
43 | * for_each_console() allows you to iterate on each console | |
44 | */ | |
45 | #define for_each_console(con) \ | |
46 | for (con = console_drivers; con != NULL; con = con->next) | |
47 | ||
076f9776 IM |
48 | /* |
49 | * Architectures can override it: | |
50 | */ | |
e17ba73b | 51 | void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...) |
076f9776 IM |
52 | { |
53 | } | |
54 | ||
1da177e4 LT |
55 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
56 | ||
57 | /* printk's without a loglevel use this.. */ | |
58 | #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ | |
59 | ||
60 | /* We show everything that is MORE important than this.. */ | |
61 | #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ | |
62 | #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ | |
63 | ||
64 | DECLARE_WAIT_QUEUE_HEAD(log_wait); | |
65 | ||
66 | int console_printk[4] = { | |
67 | DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ | |
68 | DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ | |
69 | MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ | |
70 | DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ | |
71 | }; | |
72 | ||
1da177e4 | 73 | /* |
0bbfb7c2 | 74 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
75 | * their unblank() callback or not. So let's export it. |
76 | */ | |
77 | int oops_in_progress; | |
78 | EXPORT_SYMBOL(oops_in_progress); | |
79 | ||
80 | /* | |
81 | * console_sem protects the console_drivers list, and also | |
82 | * provides serialisation for access to the entire console | |
83 | * driver system. | |
84 | */ | |
85 | static DECLARE_MUTEX(console_sem); | |
86 | struct console *console_drivers; | |
a29d1cfe IM |
87 | EXPORT_SYMBOL_GPL(console_drivers); |
88 | ||
1da177e4 LT |
89 | /* |
90 | * This is used for debugging the mess that is the VT code by | |
91 | * keeping track if we have the console semaphore held. It's | |
92 | * definitely not the perfect debug tool (we don't know if _WE_ | |
93 | * hold it are racing, but it helps tracking those weird code | |
94 | * path in the console code where we end up in places I want | |
95 | * locked without the console sempahore held | |
96 | */ | |
557240b4 | 97 | static int console_locked, console_suspended; |
1da177e4 LT |
98 | |
99 | /* | |
100 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
101 | * It is also used in interesting ways to provide interlocking in | |
102 | * release_console_sem(). | |
103 | */ | |
104 | static DEFINE_SPINLOCK(logbuf_lock); | |
105 | ||
eed4a2ab | 106 | #define LOG_BUF_MASK (log_buf_len-1) |
1da177e4 LT |
107 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
108 | ||
109 | /* | |
110 | * The indices into log_buf are not constrained to log_buf_len - they | |
111 | * must be masked before subscripting | |
112 | */ | |
eed4a2ab DV |
113 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
114 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ | |
115 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
116 | |
117 | /* | |
118 | * Array of consoles built from command line options (console=) | |
119 | */ | |
120 | struct console_cmdline | |
121 | { | |
122 | char name[8]; /* Name of the driver */ | |
123 | int index; /* Minor dev. to use */ | |
124 | char *options; /* Options for the driver */ | |
f7511d5f ST |
125 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
126 | char *brl_options; /* Options for braille driver */ | |
127 | #endif | |
1da177e4 LT |
128 | }; |
129 | ||
130 | #define MAX_CMDLINECONSOLES 8 | |
131 | ||
132 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
133 | static int selected_console = -1; | |
134 | static int preferred_console = -1; | |
9e124fe1 MA |
135 | int console_set_on_cmdline; |
136 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
137 | |
138 | /* Flag: console code may call schedule() */ | |
139 | static int console_may_schedule; | |
140 | ||
d59745ce MM |
141 | #ifdef CONFIG_PRINTK |
142 | ||
143 | static char __log_buf[__LOG_BUF_LEN]; | |
144 | static char *log_buf = __log_buf; | |
145 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 146 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
cea83886 | 147 | static int saved_console_loglevel = -1; |
d59745ce | 148 | |
04d491ab NH |
149 | #ifdef CONFIG_KEXEC |
150 | /* | |
151 | * This appends the listed symbols to /proc/vmcoreinfo | |
152 | * | |
153 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
154 | * obtain access to symbols that are otherwise very difficult to locate. These | |
155 | * symbols are specifically used so that utilities can access and extract the | |
156 | * dmesg log from a vmcore file after a crash. | |
157 | */ | |
158 | void log_buf_kexec_setup(void) | |
159 | { | |
160 | VMCOREINFO_SYMBOL(log_buf); | |
161 | VMCOREINFO_SYMBOL(log_end); | |
162 | VMCOREINFO_SYMBOL(log_buf_len); | |
163 | VMCOREINFO_SYMBOL(logged_chars); | |
164 | } | |
165 | #endif | |
166 | ||
1da177e4 LT |
167 | static int __init log_buf_len_setup(char *str) |
168 | { | |
eed4a2ab | 169 | unsigned size = memparse(str, &str); |
1da177e4 LT |
170 | unsigned long flags; |
171 | ||
172 | if (size) | |
173 | size = roundup_pow_of_two(size); | |
174 | if (size > log_buf_len) { | |
eed4a2ab | 175 | unsigned start, dest_idx, offset; |
40dc5651 | 176 | char *new_log_buf; |
1da177e4 LT |
177 | |
178 | new_log_buf = alloc_bootmem(size); | |
179 | if (!new_log_buf) { | |
40dc5651 | 180 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
181 | goto out; |
182 | } | |
183 | ||
184 | spin_lock_irqsave(&logbuf_lock, flags); | |
185 | log_buf_len = size; | |
186 | log_buf = new_log_buf; | |
187 | ||
188 | offset = start = min(con_start, log_start); | |
189 | dest_idx = 0; | |
190 | while (start != log_end) { | |
191 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
192 | start++; | |
193 | dest_idx++; | |
194 | } | |
195 | log_start -= offset; | |
196 | con_start -= offset; | |
197 | log_end -= offset; | |
198 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
199 | ||
40dc5651 | 200 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
201 | } |
202 | out: | |
1da177e4 LT |
203 | return 1; |
204 | } | |
205 | ||
206 | __setup("log_buf_len=", log_buf_len_setup); | |
207 | ||
bfe8df3d RD |
208 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
209 | ||
210 | static unsigned int boot_delay; /* msecs delay after each printk during bootup */ | |
3a3b6ed2 | 211 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
212 | |
213 | static int __init boot_delay_setup(char *str) | |
214 | { | |
215 | unsigned long lpj; | |
bfe8df3d RD |
216 | |
217 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
218 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
219 | ||
220 | get_option(&str, &boot_delay); | |
221 | if (boot_delay > 10 * 1000) | |
222 | boot_delay = 0; | |
223 | ||
3a3b6ed2 DY |
224 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
225 | "HZ: %d, loops_per_msec: %llu\n", | |
226 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
bfe8df3d RD |
227 | return 1; |
228 | } | |
229 | __setup("boot_delay=", boot_delay_setup); | |
230 | ||
231 | static void boot_delay_msec(void) | |
232 | { | |
233 | unsigned long long k; | |
234 | unsigned long timeout; | |
235 | ||
236 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
237 | return; | |
238 | ||
3a3b6ed2 | 239 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
240 | |
241 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
242 | while (k) { | |
243 | k--; | |
244 | cpu_relax(); | |
245 | /* | |
246 | * use (volatile) jiffies to prevent | |
247 | * compiler reduction; loop termination via jiffies | |
248 | * is secondary and may or may not happen. | |
249 | */ | |
250 | if (time_after(jiffies, timeout)) | |
251 | break; | |
252 | touch_nmi_watchdog(); | |
253 | } | |
254 | } | |
255 | #else | |
256 | static inline void boot_delay_msec(void) | |
257 | { | |
258 | } | |
259 | #endif | |
260 | ||
00234592 | 261 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
1da177e4 | 262 | { |
eed4a2ab | 263 | unsigned i, j, limit, count; |
1da177e4 LT |
264 | int do_clear = 0; |
265 | char c; | |
266 | int error = 0; | |
267 | ||
00234592 | 268 | error = security_syslog(type, from_file); |
1da177e4 LT |
269 | if (error) |
270 | return error; | |
271 | ||
272 | switch (type) { | |
d78ca3cd | 273 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 274 | break; |
d78ca3cd | 275 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 276 | break; |
d78ca3cd | 277 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 LT |
278 | error = -EINVAL; |
279 | if (!buf || len < 0) | |
280 | goto out; | |
281 | error = 0; | |
282 | if (!len) | |
283 | goto out; | |
284 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
285 | error = -EFAULT; | |
286 | goto out; | |
287 | } | |
40dc5651 JJ |
288 | error = wait_event_interruptible(log_wait, |
289 | (log_start - log_end)); | |
1da177e4 LT |
290 | if (error) |
291 | goto out; | |
292 | i = 0; | |
293 | spin_lock_irq(&logbuf_lock); | |
294 | while (!error && (log_start != log_end) && i < len) { | |
295 | c = LOG_BUF(log_start); | |
296 | log_start++; | |
297 | spin_unlock_irq(&logbuf_lock); | |
298 | error = __put_user(c,buf); | |
299 | buf++; | |
300 | i++; | |
301 | cond_resched(); | |
302 | spin_lock_irq(&logbuf_lock); | |
303 | } | |
304 | spin_unlock_irq(&logbuf_lock); | |
305 | if (!error) | |
306 | error = i; | |
307 | break; | |
d78ca3cd KC |
308 | /* Read/clear last kernel messages */ |
309 | case SYSLOG_ACTION_READ_CLEAR: | |
40dc5651 | 310 | do_clear = 1; |
1da177e4 | 311 | /* FALL THRU */ |
d78ca3cd KC |
312 | /* Read last kernel messages */ |
313 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 LT |
314 | error = -EINVAL; |
315 | if (!buf || len < 0) | |
316 | goto out; | |
317 | error = 0; | |
318 | if (!len) | |
319 | goto out; | |
320 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
321 | error = -EFAULT; | |
322 | goto out; | |
323 | } | |
324 | count = len; | |
325 | if (count > log_buf_len) | |
326 | count = log_buf_len; | |
327 | spin_lock_irq(&logbuf_lock); | |
328 | if (count > logged_chars) | |
329 | count = logged_chars; | |
330 | if (do_clear) | |
331 | logged_chars = 0; | |
332 | limit = log_end; | |
333 | /* | |
334 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 335 | * printk() could overwrite the messages |
1da177e4 LT |
336 | * we try to copy to user space. Therefore |
337 | * the messages are copied in reverse. <manfreds> | |
338 | */ | |
40dc5651 | 339 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
340 | j = limit-1-i; |
341 | if (j + log_buf_len < log_end) | |
342 | break; | |
343 | c = LOG_BUF(j); | |
344 | spin_unlock_irq(&logbuf_lock); | |
345 | error = __put_user(c,&buf[count-1-i]); | |
346 | cond_resched(); | |
347 | spin_lock_irq(&logbuf_lock); | |
348 | } | |
349 | spin_unlock_irq(&logbuf_lock); | |
350 | if (error) | |
351 | break; | |
352 | error = i; | |
40dc5651 | 353 | if (i != count) { |
1da177e4 LT |
354 | int offset = count-error; |
355 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 356 | for (i = 0; i < error; i++) { |
1da177e4 LT |
357 | if (__get_user(c,&buf[i+offset]) || |
358 | __put_user(c,&buf[i])) { | |
359 | error = -EFAULT; | |
360 | break; | |
361 | } | |
362 | cond_resched(); | |
363 | } | |
364 | } | |
365 | break; | |
d78ca3cd KC |
366 | /* Clear ring buffer */ |
367 | case SYSLOG_ACTION_CLEAR: | |
1da177e4 LT |
368 | logged_chars = 0; |
369 | break; | |
d78ca3cd KC |
370 | /* Disable logging to console */ |
371 | case SYSLOG_ACTION_CONSOLE_OFF: | |
1aaad49e FP |
372 | if (saved_console_loglevel == -1) |
373 | saved_console_loglevel = console_loglevel; | |
1da177e4 LT |
374 | console_loglevel = minimum_console_loglevel; |
375 | break; | |
d78ca3cd KC |
376 | /* Enable logging to console */ |
377 | case SYSLOG_ACTION_CONSOLE_ON: | |
1aaad49e FP |
378 | if (saved_console_loglevel != -1) { |
379 | console_loglevel = saved_console_loglevel; | |
380 | saved_console_loglevel = -1; | |
381 | } | |
1da177e4 | 382 | break; |
d78ca3cd KC |
383 | /* Set level of messages printed to console */ |
384 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 LT |
385 | error = -EINVAL; |
386 | if (len < 1 || len > 8) | |
387 | goto out; | |
388 | if (len < minimum_console_loglevel) | |
389 | len = minimum_console_loglevel; | |
390 | console_loglevel = len; | |
1aaad49e FP |
391 | /* Implicitly re-enable logging to console */ |
392 | saved_console_loglevel = -1; | |
1da177e4 LT |
393 | error = 0; |
394 | break; | |
d78ca3cd KC |
395 | /* Number of chars in the log buffer */ |
396 | case SYSLOG_ACTION_SIZE_UNREAD: | |
1da177e4 LT |
397 | error = log_end - log_start; |
398 | break; | |
d78ca3cd KC |
399 | /* Size of the log buffer */ |
400 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
401 | error = log_buf_len; |
402 | break; | |
403 | default: | |
404 | error = -EINVAL; | |
405 | break; | |
406 | } | |
407 | out: | |
408 | return error; | |
409 | } | |
410 | ||
1e7bfb21 | 411 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 412 | { |
00234592 | 413 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
1da177e4 LT |
414 | } |
415 | ||
67fc4e0c JW |
416 | #ifdef CONFIG_KGDB_KDB |
417 | /* kdb dmesg command needs access to the syslog buffer. do_syslog() | |
418 | * uses locks so it cannot be used during debugging. Just tell kdb | |
419 | * where the start and end of the physical and logical logs are. This | |
420 | * is equivalent to do_syslog(3). | |
421 | */ | |
422 | void kdb_syslog_data(char *syslog_data[4]) | |
423 | { | |
424 | syslog_data[0] = log_buf; | |
425 | syslog_data[1] = log_buf + log_buf_len; | |
426 | syslog_data[2] = log_buf + log_end - | |
427 | (logged_chars < log_buf_len ? logged_chars : log_buf_len); | |
428 | syslog_data[3] = log_buf + log_end; | |
429 | } | |
430 | #endif /* CONFIG_KGDB_KDB */ | |
431 | ||
1da177e4 LT |
432 | /* |
433 | * Call the console drivers on a range of log_buf | |
434 | */ | |
eed4a2ab | 435 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
436 | { |
437 | struct console *con; | |
438 | ||
4d091611 | 439 | for_each_console(con) { |
76a8ad29 ME |
440 | if ((con->flags & CON_ENABLED) && con->write && |
441 | (cpu_online(smp_processor_id()) || | |
442 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
443 | con->write(con, &LOG_BUF(start), end - start); |
444 | } | |
445 | } | |
446 | ||
79290822 IM |
447 | static int __read_mostly ignore_loglevel; |
448 | ||
99eea6a1 | 449 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
450 | { |
451 | ignore_loglevel = 1; | |
452 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
453 | ||
c4772d99 | 454 | return 0; |
79290822 IM |
455 | } |
456 | ||
c4772d99 | 457 | early_param("ignore_loglevel", ignore_loglevel_setup); |
79290822 | 458 | |
1da177e4 LT |
459 | /* |
460 | * Write out chars from start to end - 1 inclusive | |
461 | */ | |
eed4a2ab DV |
462 | static void _call_console_drivers(unsigned start, |
463 | unsigned end, int msg_log_level) | |
1da177e4 | 464 | { |
79290822 | 465 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
466 | console_drivers && start != end) { |
467 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
468 | /* wrapped write */ | |
469 | __call_console_drivers(start & LOG_BUF_MASK, | |
470 | log_buf_len); | |
471 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
472 | } else { | |
473 | __call_console_drivers(start, end); | |
474 | } | |
475 | } | |
476 | } | |
477 | ||
478 | /* | |
479 | * Call the console drivers, asking them to write out | |
480 | * log_buf[start] to log_buf[end - 1]. | |
481 | * The console_sem must be held. | |
482 | */ | |
eed4a2ab | 483 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 484 | { |
eed4a2ab | 485 | unsigned cur_index, start_print; |
1da177e4 LT |
486 | static int msg_level = -1; |
487 | ||
eed4a2ab | 488 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
489 | |
490 | cur_index = start; | |
491 | start_print = start; | |
492 | while (cur_index != end) { | |
40dc5651 JJ |
493 | if (msg_level < 0 && ((end - cur_index) > 2) && |
494 | LOG_BUF(cur_index + 0) == '<' && | |
495 | LOG_BUF(cur_index + 1) >= '0' && | |
496 | LOG_BUF(cur_index + 1) <= '7' && | |
497 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
498 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
499 | cur_index += 3; | |
500 | start_print = cur_index; | |
501 | } | |
502 | while (cur_index != end) { | |
503 | char c = LOG_BUF(cur_index); | |
1da177e4 | 504 | |
40dc5651 | 505 | cur_index++; |
1da177e4 LT |
506 | if (c == '\n') { |
507 | if (msg_level < 0) { | |
508 | /* | |
509 | * printk() has already given us loglevel tags in | |
510 | * the buffer. This code is here in case the | |
511 | * log buffer has wrapped right round and scribbled | |
512 | * on those tags | |
513 | */ | |
514 | msg_level = default_message_loglevel; | |
515 | } | |
516 | _call_console_drivers(start_print, cur_index, msg_level); | |
517 | msg_level = -1; | |
518 | start_print = cur_index; | |
519 | break; | |
520 | } | |
521 | } | |
522 | } | |
523 | _call_console_drivers(start_print, end, msg_level); | |
524 | } | |
525 | ||
526 | static void emit_log_char(char c) | |
527 | { | |
528 | LOG_BUF(log_end) = c; | |
529 | log_end++; | |
530 | if (log_end - log_start > log_buf_len) | |
531 | log_start = log_end - log_buf_len; | |
532 | if (log_end - con_start > log_buf_len) | |
533 | con_start = log_end - log_buf_len; | |
534 | if (logged_chars < log_buf_len) | |
535 | logged_chars++; | |
536 | } | |
537 | ||
538 | /* | |
539 | * Zap console related locks when oopsing. Only zap at most once | |
540 | * every 10 seconds, to leave time for slow consoles to print a | |
541 | * full oops. | |
542 | */ | |
543 | static void zap_locks(void) | |
544 | { | |
545 | static unsigned long oops_timestamp; | |
546 | ||
547 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 548 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
549 | return; |
550 | ||
551 | oops_timestamp = jiffies; | |
552 | ||
553 | /* If a crash is occurring, make sure we can't deadlock */ | |
554 | spin_lock_init(&logbuf_lock); | |
555 | /* And make sure that we print immediately */ | |
556 | init_MUTEX(&console_sem); | |
557 | } | |
558 | ||
559 | #if defined(CONFIG_PRINTK_TIME) | |
560 | static int printk_time = 1; | |
561 | #else | |
562 | static int printk_time = 0; | |
563 | #endif | |
e84845c4 | 564 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 565 | |
76a8ad29 ME |
566 | /* Check if we have any console registered that can be called early in boot. */ |
567 | static int have_callable_console(void) | |
568 | { | |
569 | struct console *con; | |
570 | ||
4d091611 | 571 | for_each_console(con) |
76a8ad29 ME |
572 | if (con->flags & CON_ANYTIME) |
573 | return 1; | |
574 | ||
575 | return 0; | |
576 | } | |
577 | ||
ddad86c2 MW |
578 | /** |
579 | * printk - print a kernel message | |
580 | * @fmt: format string | |
581 | * | |
72fd4a35 | 582 | * This is printk(). It can be called from any context. We want it to work. |
40dc5651 | 583 | * |
1da177e4 LT |
584 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
585 | * call the console drivers. If we fail to get the semaphore we place the output | |
586 | * into the log buffer and return. The current holder of the console_sem will | |
587 | * notice the new output in release_console_sem() and will send it to the | |
588 | * consoles before releasing the semaphore. | |
589 | * | |
590 | * One effect of this deferred printing is that code which calls printk() and | |
591 | * then changes console_loglevel may break. This is because console_loglevel | |
592 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
593 | * |
594 | * See also: | |
595 | * printf(3) | |
20036fdc AK |
596 | * |
597 | * See the vsnprintf() documentation for format string extensions over C99. | |
1da177e4 | 598 | */ |
d59745ce | 599 | |
1da177e4 LT |
600 | asmlinkage int printk(const char *fmt, ...) |
601 | { | |
602 | va_list args; | |
603 | int r; | |
604 | ||
605 | va_start(args, fmt); | |
606 | r = vprintk(fmt, args); | |
607 | va_end(args); | |
608 | ||
609 | return r; | |
610 | } | |
611 | ||
fe21773d DH |
612 | /* cpu currently holding logbuf_lock */ |
613 | static volatile unsigned int printk_cpu = UINT_MAX; | |
614 | ||
266c2e0a LT |
615 | /* |
616 | * Can we actually use the console at this time on this cpu? | |
617 | * | |
618 | * Console drivers may assume that per-cpu resources have | |
619 | * been allocated. So unless they're explicitly marked as | |
620 | * being able to cope (CON_ANYTIME) don't call them until | |
621 | * this CPU is officially up. | |
622 | */ | |
623 | static inline int can_use_console(unsigned int cpu) | |
624 | { | |
625 | return cpu_online(cpu) || have_callable_console(); | |
626 | } | |
627 | ||
628 | /* | |
629 | * Try to get console ownership to actually show the kernel | |
630 | * messages from a 'printk'. Return true (and with the | |
631 | * console_semaphore held, and 'console_locked' set) if it | |
632 | * is successful, false otherwise. | |
633 | * | |
634 | * This gets called with the 'logbuf_lock' spinlock held and | |
635 | * interrupts disabled. It should return with 'lockbuf_lock' | |
636 | * released but interrupts still disabled. | |
637 | */ | |
638 | static int acquire_console_semaphore_for_printk(unsigned int cpu) | |
639 | { | |
640 | int retval = 0; | |
641 | ||
093a07e2 LT |
642 | if (!try_acquire_console_sem()) { |
643 | retval = 1; | |
644 | ||
645 | /* | |
646 | * If we can't use the console, we need to release | |
647 | * the console semaphore by hand to avoid flushing | |
648 | * the buffer. We need to hold the console semaphore | |
649 | * in order to do this test safely. | |
650 | */ | |
651 | if (!can_use_console(cpu)) { | |
652 | console_locked = 0; | |
653 | up(&console_sem); | |
654 | retval = 0; | |
655 | } | |
656 | } | |
266c2e0a LT |
657 | printk_cpu = UINT_MAX; |
658 | spin_unlock(&logbuf_lock); | |
659 | return retval; | |
660 | } | |
3b8945e8 TH |
661 | static const char recursion_bug_msg [] = |
662 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
663 | static int recursion_bug; | |
edb123e1 | 664 | static int new_text_line = 1; |
3b8945e8 | 665 | static char printk_buf[1024]; |
32a76006 | 666 | |
af91322e DY |
667 | int printk_delay_msec __read_mostly; |
668 | ||
669 | static inline void printk_delay(void) | |
670 | { | |
671 | if (unlikely(printk_delay_msec)) { | |
672 | int m = printk_delay_msec; | |
673 | ||
674 | while (m--) { | |
675 | mdelay(1); | |
676 | touch_nmi_watchdog(); | |
677 | } | |
678 | } | |
679 | } | |
680 | ||
1da177e4 LT |
681 | asmlinkage int vprintk(const char *fmt, va_list args) |
682 | { | |
32a76006 | 683 | int printed_len = 0; |
09159308 | 684 | int current_log_level = default_message_loglevel; |
ac60ad74 | 685 | unsigned long flags; |
32a76006 | 686 | int this_cpu; |
1da177e4 | 687 | char *p; |
1da177e4 | 688 | |
bfe8df3d | 689 | boot_delay_msec(); |
af91322e | 690 | printk_delay(); |
bfe8df3d | 691 | |
fe21773d | 692 | preempt_disable(); |
1da177e4 | 693 | /* This stops the holder of console_sem just where we want him */ |
1efc5da3 | 694 | raw_local_irq_save(flags); |
32a76006 IM |
695 | this_cpu = smp_processor_id(); |
696 | ||
697 | /* | |
698 | * Ouch, printk recursed into itself! | |
699 | */ | |
700 | if (unlikely(printk_cpu == this_cpu)) { | |
701 | /* | |
702 | * If a crash is occurring during printk() on this CPU, | |
703 | * then try to get the crash message out but make sure | |
704 | * we can't deadlock. Otherwise just return to avoid the | |
705 | * recursion and return - but flag the recursion so that | |
706 | * it can be printed at the next appropriate moment: | |
707 | */ | |
708 | if (!oops_in_progress) { | |
3b8945e8 | 709 | recursion_bug = 1; |
32a76006 IM |
710 | goto out_restore_irqs; |
711 | } | |
712 | zap_locks(); | |
713 | } | |
714 | ||
a0f1ccfd IM |
715 | lockdep_off(); |
716 | spin_lock(&logbuf_lock); | |
32a76006 | 717 | printk_cpu = this_cpu; |
1da177e4 | 718 | |
3b8945e8 TH |
719 | if (recursion_bug) { |
720 | recursion_bug = 0; | |
721 | strcpy(printk_buf, recursion_bug_msg); | |
26cc271d | 722 | printed_len = strlen(recursion_bug_msg); |
32a76006 | 723 | } |
1da177e4 | 724 | /* Emit the output into the temporary buffer */ |
32a76006 | 725 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 726 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 727 | |
ac60ad74 | 728 | |
5fd29d6c LT |
729 | p = printk_buf; |
730 | ||
731 | /* Do we have a loglevel in the string? */ | |
732 | if (p[0] == '<') { | |
733 | unsigned char c = p[1]; | |
734 | if (c && p[2] == '>') { | |
735 | switch (c) { | |
736 | case '0' ... '7': /* loglevel */ | |
737 | current_log_level = c - '0'; | |
e28d7137 LT |
738 | /* Fallthrough - make sure we're on a new line */ |
739 | case 'd': /* KERN_DEFAULT */ | |
5fd29d6c LT |
740 | if (!new_text_line) { |
741 | emit_log_char('\n'); | |
742 | new_text_line = 1; | |
743 | } | |
744 | /* Fallthrough - skip the loglevel */ | |
745 | case 'c': /* KERN_CONT */ | |
746 | p += 3; | |
747 | break; | |
748 | } | |
749 | } | |
750 | } | |
751 | ||
1da177e4 LT |
752 | /* |
753 | * Copy the output into log_buf. If the caller didn't provide | |
754 | * appropriate log level tags, we insert them here | |
755 | */ | |
5fd29d6c | 756 | for ( ; *p; p++) { |
ac60ad74 | 757 | if (new_text_line) { |
ac60ad74 NA |
758 | /* Always output the token */ |
759 | emit_log_char('<'); | |
760 | emit_log_char(current_log_level + '0'); | |
761 | emit_log_char('>'); | |
762 | printed_len += 3; | |
763 | new_text_line = 0; | |
764 | ||
1da177e4 | 765 | if (printk_time) { |
ac60ad74 | 766 | /* Follow the token with the time */ |
1da177e4 LT |
767 | char tbuf[50], *tp; |
768 | unsigned tlen; | |
769 | unsigned long long t; | |
770 | unsigned long nanosec_rem; | |
771 | ||
326e96b9 | 772 | t = cpu_clock(printk_cpu); |
1da177e4 | 773 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
774 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
775 | (unsigned long) t, | |
776 | nanosec_rem / 1000); | |
1da177e4 LT |
777 | |
778 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
779 | emit_log_char(*tp); | |
025510cd | 780 | printed_len += tlen; |
1da177e4 | 781 | } |
ac60ad74 | 782 | |
1da177e4 LT |
783 | if (!*p) |
784 | break; | |
785 | } | |
ac60ad74 | 786 | |
1da177e4 LT |
787 | emit_log_char(*p); |
788 | if (*p == '\n') | |
ac60ad74 | 789 | new_text_line = 1; |
1da177e4 LT |
790 | } |
791 | ||
266c2e0a LT |
792 | /* |
793 | * Try to acquire and then immediately release the | |
794 | * console semaphore. The release will do all the | |
795 | * actual magic (print out buffers, wake up klogd, | |
796 | * etc). | |
797 | * | |
798 | * The acquire_console_semaphore_for_printk() function | |
799 | * will release 'logbuf_lock' regardless of whether it | |
800 | * actually gets the semaphore or not. | |
801 | */ | |
802 | if (acquire_console_semaphore_for_printk(this_cpu)) | |
803 | release_console_sem(); | |
76a8ad29 | 804 | |
266c2e0a | 805 | lockdep_on(); |
32a76006 | 806 | out_restore_irqs: |
266c2e0a | 807 | raw_local_irq_restore(flags); |
76a8ad29 | 808 | |
fe21773d | 809 | preempt_enable(); |
1da177e4 LT |
810 | return printed_len; |
811 | } | |
812 | EXPORT_SYMBOL(printk); | |
813 | EXPORT_SYMBOL(vprintk); | |
814 | ||
d59745ce MM |
815 | #else |
816 | ||
eed4a2ab | 817 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
818 | { |
819 | } | |
d59745ce MM |
820 | |
821 | #endif | |
822 | ||
f7511d5f ST |
823 | static int __add_preferred_console(char *name, int idx, char *options, |
824 | char *brl_options) | |
825 | { | |
826 | struct console_cmdline *c; | |
827 | int i; | |
828 | ||
829 | /* | |
830 | * See if this tty is not yet registered, and | |
831 | * if we have a slot free. | |
832 | */ | |
833 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
834 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
835 | console_cmdline[i].index == idx) { | |
836 | if (!brl_options) | |
837 | selected_console = i; | |
838 | return 0; | |
839 | } | |
840 | if (i == MAX_CMDLINECONSOLES) | |
841 | return -E2BIG; | |
842 | if (!brl_options) | |
843 | selected_console = i; | |
844 | c = &console_cmdline[i]; | |
845 | strlcpy(c->name, name, sizeof(c->name)); | |
846 | c->options = options; | |
847 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
848 | c->brl_options = brl_options; | |
849 | #endif | |
850 | c->index = idx; | |
851 | return 0; | |
852 | } | |
2ea1c539 JB |
853 | /* |
854 | * Set up a list of consoles. Called from init/main.c | |
855 | */ | |
856 | static int __init console_setup(char *str) | |
857 | { | |
eaa944af | 858 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 859 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
860 | int idx; |
861 | ||
f7511d5f ST |
862 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
863 | if (!memcmp(str, "brl,", 4)) { | |
864 | brl_options = ""; | |
865 | str += 4; | |
866 | } else if (!memcmp(str, "brl=", 4)) { | |
867 | brl_options = str + 4; | |
868 | str = strchr(brl_options, ','); | |
869 | if (!str) { | |
870 | printk(KERN_ERR "need port name after brl=\n"); | |
871 | return 1; | |
872 | } | |
873 | *(str++) = 0; | |
874 | } | |
875 | #endif | |
876 | ||
2ea1c539 JB |
877 | /* |
878 | * Decode str into name, index, options. | |
879 | */ | |
880 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
881 | strcpy(buf, "ttyS"); |
882 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 883 | } else { |
eaa944af | 884 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 885 | } |
eaa944af | 886 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
887 | if ((options = strchr(str, ',')) != NULL) |
888 | *(options++) = 0; | |
889 | #ifdef __sparc__ | |
890 | if (!strcmp(str, "ttya")) | |
eaa944af | 891 | strcpy(buf, "ttyS0"); |
2ea1c539 | 892 | if (!strcmp(str, "ttyb")) |
eaa944af | 893 | strcpy(buf, "ttyS1"); |
2ea1c539 | 894 | #endif |
eaa944af | 895 | for (s = buf; *s; s++) |
2ea1c539 JB |
896 | if ((*s >= '0' && *s <= '9') || *s == ',') |
897 | break; | |
898 | idx = simple_strtoul(s, NULL, 10); | |
899 | *s = 0; | |
900 | ||
f7511d5f | 901 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 902 | console_set_on_cmdline = 1; |
2ea1c539 JB |
903 | return 1; |
904 | } | |
905 | __setup("console=", console_setup); | |
906 | ||
3c0547ba MM |
907 | /** |
908 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
909 | * @name: device name |
910 | * @idx: device index | |
911 | * @options: options for this console | |
3c0547ba MM |
912 | * |
913 | * The last preferred console added will be used for kernel messages | |
914 | * and stdin/out/err for init. Normally this is used by console_setup | |
915 | * above to handle user-supplied console arguments; however it can also | |
916 | * be used by arch-specific code either to override the user or more | |
917 | * commonly to provide a default console (ie from PROM variables) when | |
918 | * the user has not supplied one. | |
919 | */ | |
fb445ee5 | 920 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 921 | { |
f7511d5f | 922 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
923 | } |
924 | ||
b6b1d877 | 925 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
926 | { |
927 | struct console_cmdline *c; | |
928 | int i; | |
929 | ||
930 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
931 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
932 | console_cmdline[i].index == idx) { | |
933 | c = &console_cmdline[i]; | |
f735295b | 934 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
935 | c->name[sizeof(c->name) - 1] = 0; |
936 | c->options = options; | |
937 | c->index = idx_new; | |
938 | return i; | |
939 | } | |
940 | /* not found */ | |
941 | return -1; | |
942 | } | |
943 | ||
8f4ce8c3 AS |
944 | int console_suspend_enabled = 1; |
945 | EXPORT_SYMBOL(console_suspend_enabled); | |
946 | ||
947 | static int __init console_suspend_disable(char *str) | |
948 | { | |
949 | console_suspend_enabled = 0; | |
950 | return 1; | |
951 | } | |
952 | __setup("no_console_suspend", console_suspend_disable); | |
953 | ||
557240b4 LT |
954 | /** |
955 | * suspend_console - suspend the console subsystem | |
956 | * | |
957 | * This disables printk() while we go into suspend states | |
958 | */ | |
959 | void suspend_console(void) | |
960 | { | |
8f4ce8c3 AS |
961 | if (!console_suspend_enabled) |
962 | return; | |
0d63081d | 963 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
557240b4 LT |
964 | acquire_console_sem(); |
965 | console_suspended = 1; | |
403f3075 | 966 | up(&console_sem); |
557240b4 LT |
967 | } |
968 | ||
969 | void resume_console(void) | |
970 | { | |
8f4ce8c3 AS |
971 | if (!console_suspend_enabled) |
972 | return; | |
403f3075 | 973 | down(&console_sem); |
557240b4 LT |
974 | console_suspended = 0; |
975 | release_console_sem(); | |
976 | } | |
977 | ||
1da177e4 LT |
978 | /** |
979 | * acquire_console_sem - lock the console system for exclusive use. | |
980 | * | |
981 | * Acquires a semaphore which guarantees that the caller has | |
982 | * exclusive access to the console system and the console_drivers list. | |
983 | * | |
984 | * Can sleep, returns nothing. | |
985 | */ | |
986 | void acquire_console_sem(void) | |
987 | { | |
8abd8e29 | 988 | BUG_ON(in_interrupt()); |
1da177e4 | 989 | down(&console_sem); |
403f3075 AH |
990 | if (console_suspended) |
991 | return; | |
1da177e4 LT |
992 | console_locked = 1; |
993 | console_may_schedule = 1; | |
994 | } | |
995 | EXPORT_SYMBOL(acquire_console_sem); | |
996 | ||
997 | int try_acquire_console_sem(void) | |
998 | { | |
999 | if (down_trylock(&console_sem)) | |
1000 | return -1; | |
403f3075 AH |
1001 | if (console_suspended) { |
1002 | up(&console_sem); | |
1003 | return -1; | |
1004 | } | |
1da177e4 LT |
1005 | console_locked = 1; |
1006 | console_may_schedule = 0; | |
1007 | return 0; | |
1008 | } | |
1009 | EXPORT_SYMBOL(try_acquire_console_sem); | |
1010 | ||
1011 | int is_console_locked(void) | |
1012 | { | |
1013 | return console_locked; | |
1014 | } | |
1da177e4 | 1015 | |
b845b517 PZ |
1016 | static DEFINE_PER_CPU(int, printk_pending); |
1017 | ||
1018 | void printk_tick(void) | |
e3e8a75d | 1019 | { |
b845b517 PZ |
1020 | if (__get_cpu_var(printk_pending)) { |
1021 | __get_cpu_var(printk_pending) = 0; | |
e3e8a75d | 1022 | wake_up_interruptible(&log_wait); |
b845b517 PZ |
1023 | } |
1024 | } | |
1025 | ||
1026 | int printk_needs_cpu(int cpu) | |
1027 | { | |
1028 | return per_cpu(printk_pending, cpu); | |
1029 | } | |
1030 | ||
1031 | void wake_up_klogd(void) | |
1032 | { | |
1033 | if (waitqueue_active(&log_wait)) | |
fa33507a | 1034 | __raw_get_cpu_var(printk_pending) = 1; |
e3e8a75d KK |
1035 | } |
1036 | ||
1da177e4 LT |
1037 | /** |
1038 | * release_console_sem - unlock the console system | |
1039 | * | |
1040 | * Releases the semaphore which the caller holds on the console system | |
1041 | * and the console driver list. | |
1042 | * | |
1043 | * While the semaphore was held, console output may have been buffered | |
1044 | * by printk(). If this is the case, release_console_sem() emits | |
1045 | * the output prior to releasing the semaphore. | |
1046 | * | |
1047 | * If there is output waiting for klogd, we wake it up. | |
1048 | * | |
1049 | * release_console_sem() may be called from any context. | |
1050 | */ | |
1051 | void release_console_sem(void) | |
1052 | { | |
1053 | unsigned long flags; | |
eed4a2ab DV |
1054 | unsigned _con_start, _log_end; |
1055 | unsigned wake_klogd = 0; | |
1da177e4 | 1056 | |
557240b4 | 1057 | if (console_suspended) { |
403f3075 | 1058 | up(&console_sem); |
557240b4 LT |
1059 | return; |
1060 | } | |
78944e54 AD |
1061 | |
1062 | console_may_schedule = 0; | |
1063 | ||
1da177e4 LT |
1064 | for ( ; ; ) { |
1065 | spin_lock_irqsave(&logbuf_lock, flags); | |
1066 | wake_klogd |= log_start - log_end; | |
1067 | if (con_start == log_end) | |
1068 | break; /* Nothing to print */ | |
1069 | _con_start = con_start; | |
1070 | _log_end = log_end; | |
1071 | con_start = log_end; /* Flush */ | |
1072 | spin_unlock(&logbuf_lock); | |
81d68a96 | 1073 | stop_critical_timings(); /* don't trace print latency */ |
1da177e4 | 1074 | call_console_drivers(_con_start, _log_end); |
81d68a96 | 1075 | start_critical_timings(); |
1da177e4 LT |
1076 | local_irq_restore(flags); |
1077 | } | |
1078 | console_locked = 0; | |
1da177e4 LT |
1079 | up(&console_sem); |
1080 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
1081 | if (wake_klogd) |
1082 | wake_up_klogd(); | |
1da177e4 LT |
1083 | } |
1084 | EXPORT_SYMBOL(release_console_sem); | |
1085 | ||
ddad86c2 MW |
1086 | /** |
1087 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1088 | * |
1089 | * If the console code is currently allowed to sleep, and | |
1090 | * if this CPU should yield the CPU to another task, do | |
1091 | * so here. | |
1092 | * | |
1093 | * Must be called within acquire_console_sem(). | |
1094 | */ | |
1095 | void __sched console_conditional_schedule(void) | |
1096 | { | |
1097 | if (console_may_schedule) | |
1098 | cond_resched(); | |
1099 | } | |
1100 | EXPORT_SYMBOL(console_conditional_schedule); | |
1101 | ||
1da177e4 LT |
1102 | void console_unblank(void) |
1103 | { | |
1104 | struct console *c; | |
1105 | ||
1106 | /* | |
1107 | * console_unblank can no longer be called in interrupt context unless | |
1108 | * oops_in_progress is set to 1.. | |
1109 | */ | |
1110 | if (oops_in_progress) { | |
1111 | if (down_trylock(&console_sem) != 0) | |
1112 | return; | |
1113 | } else | |
1114 | acquire_console_sem(); | |
1115 | ||
1116 | console_locked = 1; | |
1117 | console_may_schedule = 0; | |
4d091611 | 1118 | for_each_console(c) |
1da177e4 LT |
1119 | if ((c->flags & CON_ENABLED) && c->unblank) |
1120 | c->unblank(); | |
1121 | release_console_sem(); | |
1122 | } | |
1da177e4 LT |
1123 | |
1124 | /* | |
1125 | * Return the console tty driver structure and its associated index | |
1126 | */ | |
1127 | struct tty_driver *console_device(int *index) | |
1128 | { | |
1129 | struct console *c; | |
1130 | struct tty_driver *driver = NULL; | |
1131 | ||
1132 | acquire_console_sem(); | |
4d091611 | 1133 | for_each_console(c) { |
1da177e4 LT |
1134 | if (!c->device) |
1135 | continue; | |
1136 | driver = c->device(c, index); | |
1137 | if (driver) | |
1138 | break; | |
1139 | } | |
1140 | release_console_sem(); | |
1141 | return driver; | |
1142 | } | |
1143 | ||
1144 | /* | |
1145 | * Prevent further output on the passed console device so that (for example) | |
1146 | * serial drivers can disable console output before suspending a port, and can | |
1147 | * re-enable output afterwards. | |
1148 | */ | |
1149 | void console_stop(struct console *console) | |
1150 | { | |
1151 | acquire_console_sem(); | |
1152 | console->flags &= ~CON_ENABLED; | |
1153 | release_console_sem(); | |
1154 | } | |
1155 | EXPORT_SYMBOL(console_stop); | |
1156 | ||
1157 | void console_start(struct console *console) | |
1158 | { | |
1159 | acquire_console_sem(); | |
1160 | console->flags |= CON_ENABLED; | |
1161 | release_console_sem(); | |
1162 | } | |
1163 | EXPORT_SYMBOL(console_start); | |
1164 | ||
1165 | /* | |
1166 | * The console driver calls this routine during kernel initialization | |
1167 | * to register the console printing procedure with printk() and to | |
1168 | * print any messages that were printed by the kernel before the | |
1169 | * console driver was initialized. | |
4d091611 RG |
1170 | * |
1171 | * This can happen pretty early during the boot process (because of | |
1172 | * early_printk) - sometimes before setup_arch() completes - be careful | |
1173 | * of what kernel features are used - they may not be initialised yet. | |
1174 | * | |
1175 | * There are two types of consoles - bootconsoles (early_printk) and | |
1176 | * "real" consoles (everything which is not a bootconsole) which are | |
1177 | * handled differently. | |
1178 | * - Any number of bootconsoles can be registered at any time. | |
1179 | * - As soon as a "real" console is registered, all bootconsoles | |
1180 | * will be unregistered automatically. | |
1181 | * - Once a "real" console is registered, any attempt to register a | |
1182 | * bootconsoles will be rejected | |
1da177e4 | 1183 | */ |
4d091611 | 1184 | void register_console(struct console *newcon) |
1da177e4 | 1185 | { |
40dc5651 | 1186 | int i; |
1da177e4 | 1187 | unsigned long flags; |
4d091611 | 1188 | struct console *bcon = NULL; |
1da177e4 | 1189 | |
4d091611 RG |
1190 | /* |
1191 | * before we register a new CON_BOOT console, make sure we don't | |
1192 | * already have a valid console | |
1193 | */ | |
1194 | if (console_drivers && newcon->flags & CON_BOOT) { | |
1195 | /* find the last or real console */ | |
1196 | for_each_console(bcon) { | |
1197 | if (!(bcon->flags & CON_BOOT)) { | |
1198 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", | |
1199 | newcon->name, newcon->index); | |
1200 | return; | |
1201 | } | |
1202 | } | |
69331af7 GH |
1203 | } |
1204 | ||
4d091611 RG |
1205 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1206 | bcon = console_drivers; | |
1207 | ||
1208 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
1209 | preferred_console = selected_console; |
1210 | ||
4d091611 RG |
1211 | if (newcon->early_setup) |
1212 | newcon->early_setup(); | |
18a8bd94 | 1213 | |
1da177e4 LT |
1214 | /* |
1215 | * See if we want to use this console driver. If we | |
1216 | * didn't select a console we take the first one | |
1217 | * that registers here. | |
1218 | */ | |
1219 | if (preferred_console < 0) { | |
4d091611 RG |
1220 | if (newcon->index < 0) |
1221 | newcon->index = 0; | |
1222 | if (newcon->setup == NULL || | |
1223 | newcon->setup(newcon, NULL) == 0) { | |
1224 | newcon->flags |= CON_ENABLED; | |
1225 | if (newcon->device) { | |
1226 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
1227 | preferred_console = 0; |
1228 | } | |
1da177e4 LT |
1229 | } |
1230 | } | |
1231 | ||
1232 | /* | |
1233 | * See if this console matches one we selected on | |
1234 | * the command line. | |
1235 | */ | |
40dc5651 JJ |
1236 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1237 | i++) { | |
4d091611 | 1238 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1da177e4 | 1239 | continue; |
4d091611 RG |
1240 | if (newcon->index >= 0 && |
1241 | newcon->index != console_cmdline[i].index) | |
1da177e4 | 1242 | continue; |
4d091611 RG |
1243 | if (newcon->index < 0) |
1244 | newcon->index = console_cmdline[i].index; | |
f7511d5f ST |
1245 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1246 | if (console_cmdline[i].brl_options) { | |
4d091611 RG |
1247 | newcon->flags |= CON_BRL; |
1248 | braille_register_console(newcon, | |
f7511d5f ST |
1249 | console_cmdline[i].index, |
1250 | console_cmdline[i].options, | |
1251 | console_cmdline[i].brl_options); | |
1252 | return; | |
1253 | } | |
1254 | #endif | |
4d091611 RG |
1255 | if (newcon->setup && |
1256 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 1257 | break; |
4d091611 RG |
1258 | newcon->flags |= CON_ENABLED; |
1259 | newcon->index = console_cmdline[i].index; | |
ab4af03a | 1260 | if (i == selected_console) { |
4d091611 | 1261 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
1262 | preferred_console = selected_console; |
1263 | } | |
1da177e4 LT |
1264 | break; |
1265 | } | |
1266 | ||
4d091611 | 1267 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
1268 | return; |
1269 | ||
8259cf43 RG |
1270 | /* |
1271 | * If we have a bootconsole, and are switching to a real console, | |
1272 | * don't print everything out again, since when the boot console, and | |
1273 | * the real console are the same physical device, it's annoying to | |
1274 | * see the beginning boot messages twice | |
1275 | */ | |
1276 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 1277 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
1278 | |
1279 | /* | |
1280 | * Put this console in the list - keep the | |
1281 | * preferred driver at the head of the list. | |
1282 | */ | |
1283 | acquire_console_sem(); | |
4d091611 RG |
1284 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1285 | newcon->next = console_drivers; | |
1286 | console_drivers = newcon; | |
1287 | if (newcon->next) | |
1288 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 1289 | } else { |
4d091611 RG |
1290 | newcon->next = console_drivers->next; |
1291 | console_drivers->next = newcon; | |
1da177e4 | 1292 | } |
4d091611 | 1293 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 LT |
1294 | /* |
1295 | * release_console_sem() will print out the buffered messages | |
1296 | * for us. | |
1297 | */ | |
1298 | spin_lock_irqsave(&logbuf_lock, flags); | |
1299 | con_start = log_start; | |
1300 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1301 | } | |
1302 | release_console_sem(); | |
8259cf43 RG |
1303 | |
1304 | /* | |
1305 | * By unregistering the bootconsoles after we enable the real console | |
1306 | * we get the "console xxx enabled" message on all the consoles - | |
1307 | * boot consoles, real consoles, etc - this is to ensure that end | |
1308 | * users know there might be something in the kernel's log buffer that | |
1309 | * went to the bootconsole (that they do not see on the real console) | |
1310 | */ | |
1311 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) { | |
1312 | /* we need to iterate through twice, to make sure we print | |
1313 | * everything out, before we unregister the console(s) | |
1314 | */ | |
1315 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", | |
1316 | newcon->name, newcon->index); | |
1317 | for_each_console(bcon) | |
1318 | if (bcon->flags & CON_BOOT) | |
1319 | unregister_console(bcon); | |
1320 | } else { | |
1321 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", | |
1322 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
1323 | newcon->name, newcon->index); | |
1324 | } | |
1da177e4 LT |
1325 | } |
1326 | EXPORT_SYMBOL(register_console); | |
1327 | ||
40dc5651 | 1328 | int unregister_console(struct console *console) |
1da177e4 | 1329 | { |
40dc5651 | 1330 | struct console *a, *b; |
1da177e4 LT |
1331 | int res = 1; |
1332 | ||
f7511d5f ST |
1333 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1334 | if (console->flags & CON_BRL) | |
1335 | return braille_unregister_console(console); | |
1336 | #endif | |
1337 | ||
1da177e4 LT |
1338 | acquire_console_sem(); |
1339 | if (console_drivers == console) { | |
1340 | console_drivers=console->next; | |
1341 | res = 0; | |
e9b15b54 | 1342 | } else if (console_drivers) { |
1da177e4 LT |
1343 | for (a=console_drivers->next, b=console_drivers ; |
1344 | a; b=a, a=b->next) { | |
1345 | if (a == console) { | |
1346 | b->next = a->next; | |
1347 | res = 0; | |
1348 | break; | |
40dc5651 | 1349 | } |
1da177e4 LT |
1350 | } |
1351 | } | |
40dc5651 | 1352 | |
69331af7 | 1353 | /* |
ab4af03a GE |
1354 | * If this isn't the last console and it has CON_CONSDEV set, we |
1355 | * need to set it on the next preferred console. | |
1da177e4 | 1356 | */ |
69331af7 | 1357 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1358 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 LT |
1359 | |
1360 | release_console_sem(); | |
1361 | return res; | |
1362 | } | |
1363 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1364 | |
0c5564bd RG |
1365 | static int __init disable_boot_consoles(void) |
1366 | { | |
4d091611 RG |
1367 | struct console *con; |
1368 | ||
1369 | for_each_console(con) { | |
1370 | if (con->flags & CON_BOOT) { | |
cb00e99c | 1371 | printk(KERN_INFO "turn off boot console %s%d\n", |
4d091611 | 1372 | con->name, con->index); |
42c2c8c8 | 1373 | unregister_console(con); |
cb00e99c | 1374 | } |
0c5564bd RG |
1375 | } |
1376 | return 0; | |
1377 | } | |
1378 | late_initcall(disable_boot_consoles); | |
1379 | ||
7ef3d2fd | 1380 | #if defined CONFIG_PRINTK |
717115e1 | 1381 | |
1da177e4 LT |
1382 | /* |
1383 | * printk rate limiting, lifted from the networking subsystem. | |
1384 | * | |
641de9d8 UKK |
1385 | * This enforces a rate limit: not more than 10 kernel messages |
1386 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 1387 | */ |
641de9d8 UKK |
1388 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1389 | ||
5c828713 | 1390 | int __printk_ratelimit(const char *func) |
1da177e4 | 1391 | { |
5c828713 | 1392 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 1393 | } |
5c828713 | 1394 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
1395 | |
1396 | /** | |
1397 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1398 | * @caller_jiffies: pointer to caller's state | |
1399 | * @interval_msecs: minimum interval between prints | |
1400 | * | |
1401 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1402 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1403 | * returned true. | |
1404 | */ | |
1405 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1406 | unsigned int interval_msecs) | |
1407 | { | |
f2d28a2e GK |
1408 | if (*caller_jiffies == 0 |
1409 | || !time_in_range(jiffies, *caller_jiffies, | |
1410 | *caller_jiffies | |
1411 | + msecs_to_jiffies(interval_msecs))) { | |
1412 | *caller_jiffies = jiffies; | |
f46c4833 AM |
1413 | return true; |
1414 | } | |
1415 | return false; | |
1416 | } | |
1417 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
1418 | |
1419 | static DEFINE_SPINLOCK(dump_list_lock); | |
1420 | static LIST_HEAD(dump_list); | |
1421 | ||
1422 | /** | |
1423 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 1424 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1425 | * |
1426 | * Adds a kernel log dumper to the system. The dump callback in the | |
1427 | * structure will be called when the kernel oopses or panics and must be | |
1428 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
1429 | */ | |
1430 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
1431 | { | |
1432 | unsigned long flags; | |
1433 | int err = -EBUSY; | |
1434 | ||
1435 | /* The dump callback needs to be set */ | |
1436 | if (!dumper->dump) | |
1437 | return -EINVAL; | |
1438 | ||
1439 | spin_lock_irqsave(&dump_list_lock, flags); | |
1440 | /* Don't allow registering multiple times */ | |
1441 | if (!dumper->registered) { | |
1442 | dumper->registered = 1; | |
1443 | list_add_tail(&dumper->list, &dump_list); | |
1444 | err = 0; | |
1445 | } | |
1446 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1447 | ||
1448 | return err; | |
1449 | } | |
1450 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
1451 | ||
1452 | /** | |
1453 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 1454 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1455 | * |
1456 | * Removes a dump device from the system. Returns zero on success and | |
1457 | * %-EINVAL otherwise. | |
1458 | */ | |
1459 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
1460 | { | |
1461 | unsigned long flags; | |
1462 | int err = -EINVAL; | |
1463 | ||
1464 | spin_lock_irqsave(&dump_list_lock, flags); | |
1465 | if (dumper->registered) { | |
1466 | dumper->registered = 0; | |
1467 | list_del(&dumper->list); | |
1468 | err = 0; | |
1469 | } | |
1470 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1471 | ||
1472 | return err; | |
1473 | } | |
1474 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
1475 | ||
1476 | static const char const *kmsg_reasons[] = { | |
1477 | [KMSG_DUMP_OOPS] = "oops", | |
1478 | [KMSG_DUMP_PANIC] = "panic", | |
0f4bd46e | 1479 | [KMSG_DUMP_KEXEC] = "kexec", |
456b565c SK |
1480 | }; |
1481 | ||
1482 | static const char *kmsg_to_str(enum kmsg_dump_reason reason) | |
1483 | { | |
1484 | if (reason >= ARRAY_SIZE(kmsg_reasons) || reason < 0) | |
1485 | return "unknown"; | |
1486 | ||
1487 | return kmsg_reasons[reason]; | |
1488 | } | |
1489 | ||
1490 | /** | |
1491 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
1492 | * @reason: the reason (oops, panic etc) for dumping | |
1493 | * | |
1494 | * Iterate through each of the dump devices and call the oops/panic | |
1495 | * callbacks with the log buffer. | |
1496 | */ | |
1497 | void kmsg_dump(enum kmsg_dump_reason reason) | |
1498 | { | |
1499 | unsigned long end; | |
1500 | unsigned chars; | |
1501 | struct kmsg_dumper *dumper; | |
1502 | const char *s1, *s2; | |
1503 | unsigned long l1, l2; | |
1504 | unsigned long flags; | |
1505 | ||
1506 | /* Theoretically, the log could move on after we do this, but | |
1507 | there's not a lot we can do about that. The new messages | |
1508 | will overwrite the start of what we dump. */ | |
1509 | spin_lock_irqsave(&logbuf_lock, flags); | |
1510 | end = log_end & LOG_BUF_MASK; | |
1511 | chars = logged_chars; | |
1512 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1513 | ||
1514 | if (logged_chars > end) { | |
1515 | s1 = log_buf + log_buf_len - logged_chars + end; | |
1516 | l1 = logged_chars - end; | |
1517 | ||
1518 | s2 = log_buf; | |
1519 | l2 = end; | |
1520 | } else { | |
1521 | s1 = ""; | |
1522 | l1 = 0; | |
1523 | ||
1524 | s2 = log_buf + end - logged_chars; | |
1525 | l2 = logged_chars; | |
1526 | } | |
1527 | ||
1528 | if (!spin_trylock_irqsave(&dump_list_lock, flags)) { | |
1529 | printk(KERN_ERR "dump_kmsg: dump list lock is held during %s, skipping dump\n", | |
1530 | kmsg_to_str(reason)); | |
1531 | return; | |
1532 | } | |
1533 | list_for_each_entry(dumper, &dump_list, list) | |
1534 | dumper->dump(dumper, reason, s1, l1, s2, l2); | |
1535 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1536 | } | |
7ef3d2fd | 1537 | #endif |