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Commit | Line | Data |
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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 | ||
1aaad49e FP |
73 | static int saved_console_loglevel = -1; |
74 | ||
1da177e4 | 75 | /* |
0bbfb7c2 | 76 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
77 | * their unblank() callback or not. So let's export it. |
78 | */ | |
79 | int oops_in_progress; | |
80 | EXPORT_SYMBOL(oops_in_progress); | |
81 | ||
82 | /* | |
83 | * console_sem protects the console_drivers list, and also | |
84 | * provides serialisation for access to the entire console | |
85 | * driver system. | |
86 | */ | |
87 | static DECLARE_MUTEX(console_sem); | |
88 | struct console *console_drivers; | |
a29d1cfe IM |
89 | EXPORT_SYMBOL_GPL(console_drivers); |
90 | ||
1da177e4 LT |
91 | /* |
92 | * This is used for debugging the mess that is the VT code by | |
93 | * keeping track if we have the console semaphore held. It's | |
94 | * definitely not the perfect debug tool (we don't know if _WE_ | |
95 | * hold it are racing, but it helps tracking those weird code | |
96 | * path in the console code where we end up in places I want | |
97 | * locked without the console sempahore held | |
98 | */ | |
557240b4 | 99 | static int console_locked, console_suspended; |
1da177e4 LT |
100 | |
101 | /* | |
102 | * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars | |
103 | * It is also used in interesting ways to provide interlocking in | |
104 | * release_console_sem(). | |
105 | */ | |
106 | static DEFINE_SPINLOCK(logbuf_lock); | |
107 | ||
eed4a2ab | 108 | #define LOG_BUF_MASK (log_buf_len-1) |
1da177e4 LT |
109 | #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK]) |
110 | ||
111 | /* | |
112 | * The indices into log_buf are not constrained to log_buf_len - they | |
113 | * must be masked before subscripting | |
114 | */ | |
eed4a2ab DV |
115 | static unsigned log_start; /* Index into log_buf: next char to be read by syslog() */ |
116 | static unsigned con_start; /* Index into log_buf: next char to be sent to consoles */ | |
117 | static unsigned log_end; /* Index into log_buf: most-recently-written-char + 1 */ | |
1da177e4 LT |
118 | |
119 | /* | |
120 | * Array of consoles built from command line options (console=) | |
121 | */ | |
122 | struct console_cmdline | |
123 | { | |
124 | char name[8]; /* Name of the driver */ | |
125 | int index; /* Minor dev. to use */ | |
126 | char *options; /* Options for the driver */ | |
f7511d5f ST |
127 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
128 | char *brl_options; /* Options for braille driver */ | |
129 | #endif | |
1da177e4 LT |
130 | }; |
131 | ||
132 | #define MAX_CMDLINECONSOLES 8 | |
133 | ||
134 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
135 | static int selected_console = -1; | |
136 | static int preferred_console = -1; | |
9e124fe1 MA |
137 | int console_set_on_cmdline; |
138 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
139 | |
140 | /* Flag: console code may call schedule() */ | |
141 | static int console_may_schedule; | |
142 | ||
d59745ce MM |
143 | #ifdef CONFIG_PRINTK |
144 | ||
145 | static char __log_buf[__LOG_BUF_LEN]; | |
146 | static char *log_buf = __log_buf; | |
147 | static int log_buf_len = __LOG_BUF_LEN; | |
eed4a2ab | 148 | static unsigned logged_chars; /* Number of chars produced since last read+clear operation */ |
d59745ce | 149 | |
04d491ab NH |
150 | #ifdef CONFIG_KEXEC |
151 | /* | |
152 | * This appends the listed symbols to /proc/vmcoreinfo | |
153 | * | |
154 | * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to | |
155 | * obtain access to symbols that are otherwise very difficult to locate. These | |
156 | * symbols are specifically used so that utilities can access and extract the | |
157 | * dmesg log from a vmcore file after a crash. | |
158 | */ | |
159 | void log_buf_kexec_setup(void) | |
160 | { | |
161 | VMCOREINFO_SYMBOL(log_buf); | |
162 | VMCOREINFO_SYMBOL(log_end); | |
163 | VMCOREINFO_SYMBOL(log_buf_len); | |
164 | VMCOREINFO_SYMBOL(logged_chars); | |
165 | } | |
166 | #endif | |
167 | ||
1da177e4 LT |
168 | static int __init log_buf_len_setup(char *str) |
169 | { | |
eed4a2ab | 170 | unsigned size = memparse(str, &str); |
1da177e4 LT |
171 | unsigned long flags; |
172 | ||
173 | if (size) | |
174 | size = roundup_pow_of_two(size); | |
175 | if (size > log_buf_len) { | |
eed4a2ab | 176 | unsigned start, dest_idx, offset; |
40dc5651 | 177 | char *new_log_buf; |
1da177e4 LT |
178 | |
179 | new_log_buf = alloc_bootmem(size); | |
180 | if (!new_log_buf) { | |
40dc5651 | 181 | printk(KERN_WARNING "log_buf_len: allocation failed\n"); |
1da177e4 LT |
182 | goto out; |
183 | } | |
184 | ||
185 | spin_lock_irqsave(&logbuf_lock, flags); | |
186 | log_buf_len = size; | |
187 | log_buf = new_log_buf; | |
188 | ||
189 | offset = start = min(con_start, log_start); | |
190 | dest_idx = 0; | |
191 | while (start != log_end) { | |
192 | log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)]; | |
193 | start++; | |
194 | dest_idx++; | |
195 | } | |
196 | log_start -= offset; | |
197 | con_start -= offset; | |
198 | log_end -= offset; | |
199 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
200 | ||
40dc5651 | 201 | printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len); |
1da177e4 LT |
202 | } |
203 | out: | |
1da177e4 LT |
204 | return 1; |
205 | } | |
206 | ||
207 | __setup("log_buf_len=", log_buf_len_setup); | |
208 | ||
bfe8df3d RD |
209 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
210 | ||
211 | static unsigned int boot_delay; /* msecs delay after each printk during bootup */ | |
3a3b6ed2 | 212 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
213 | |
214 | static int __init boot_delay_setup(char *str) | |
215 | { | |
216 | unsigned long lpj; | |
bfe8df3d RD |
217 | |
218 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
219 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
220 | ||
221 | get_option(&str, &boot_delay); | |
222 | if (boot_delay > 10 * 1000) | |
223 | boot_delay = 0; | |
224 | ||
3a3b6ed2 DY |
225 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
226 | "HZ: %d, loops_per_msec: %llu\n", | |
227 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
bfe8df3d RD |
228 | return 1; |
229 | } | |
230 | __setup("boot_delay=", boot_delay_setup); | |
231 | ||
232 | static void boot_delay_msec(void) | |
233 | { | |
234 | unsigned long long k; | |
235 | unsigned long timeout; | |
236 | ||
237 | if (boot_delay == 0 || system_state != SYSTEM_BOOTING) | |
238 | return; | |
239 | ||
3a3b6ed2 | 240 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
241 | |
242 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
243 | while (k) { | |
244 | k--; | |
245 | cpu_relax(); | |
246 | /* | |
247 | * use (volatile) jiffies to prevent | |
248 | * compiler reduction; loop termination via jiffies | |
249 | * is secondary and may or may not happen. | |
250 | */ | |
251 | if (time_after(jiffies, timeout)) | |
252 | break; | |
253 | touch_nmi_watchdog(); | |
254 | } | |
255 | } | |
256 | #else | |
257 | static inline void boot_delay_msec(void) | |
258 | { | |
259 | } | |
260 | #endif | |
261 | ||
1da177e4 LT |
262 | /* |
263 | * Commands to do_syslog: | |
264 | * | |
265 | * 0 -- Close the log. Currently a NOP. | |
266 | * 1 -- Open the log. Currently a NOP. | |
267 | * 2 -- Read from the log. | |
268 | * 3 -- Read all messages remaining in the ring buffer. | |
269 | * 4 -- Read and clear all messages remaining in the ring buffer | |
270 | * 5 -- Clear ring buffer. | |
271 | * 6 -- Disable printk's to console | |
272 | * 7 -- Enable printk's to console | |
273 | * 8 -- Set level of messages printed to console | |
274 | * 9 -- Return number of unread characters in the log buffer | |
275 | * 10 -- Return size of the log buffer | |
276 | */ | |
00234592 | 277 | int do_syslog(int type, char __user *buf, int len, bool from_file) |
1da177e4 | 278 | { |
eed4a2ab | 279 | unsigned i, j, limit, count; |
1da177e4 LT |
280 | int do_clear = 0; |
281 | char c; | |
282 | int error = 0; | |
283 | ||
00234592 | 284 | error = security_syslog(type, from_file); |
1da177e4 LT |
285 | if (error) |
286 | return error; | |
287 | ||
288 | switch (type) { | |
289 | case 0: /* Close log */ | |
290 | break; | |
291 | case 1: /* Open log */ | |
292 | break; | |
293 | case 2: /* Read from log */ | |
294 | error = -EINVAL; | |
295 | if (!buf || len < 0) | |
296 | goto out; | |
297 | error = 0; | |
298 | if (!len) | |
299 | goto out; | |
300 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
301 | error = -EFAULT; | |
302 | goto out; | |
303 | } | |
40dc5651 JJ |
304 | error = wait_event_interruptible(log_wait, |
305 | (log_start - log_end)); | |
1da177e4 LT |
306 | if (error) |
307 | goto out; | |
308 | i = 0; | |
309 | spin_lock_irq(&logbuf_lock); | |
310 | while (!error && (log_start != log_end) && i < len) { | |
311 | c = LOG_BUF(log_start); | |
312 | log_start++; | |
313 | spin_unlock_irq(&logbuf_lock); | |
314 | error = __put_user(c,buf); | |
315 | buf++; | |
316 | i++; | |
317 | cond_resched(); | |
318 | spin_lock_irq(&logbuf_lock); | |
319 | } | |
320 | spin_unlock_irq(&logbuf_lock); | |
321 | if (!error) | |
322 | error = i; | |
323 | break; | |
324 | case 4: /* Read/clear last kernel messages */ | |
40dc5651 | 325 | do_clear = 1; |
1da177e4 LT |
326 | /* FALL THRU */ |
327 | case 3: /* Read last kernel messages */ | |
328 | error = -EINVAL; | |
329 | if (!buf || len < 0) | |
330 | goto out; | |
331 | error = 0; | |
332 | if (!len) | |
333 | goto out; | |
334 | if (!access_ok(VERIFY_WRITE, buf, len)) { | |
335 | error = -EFAULT; | |
336 | goto out; | |
337 | } | |
338 | count = len; | |
339 | if (count > log_buf_len) | |
340 | count = log_buf_len; | |
341 | spin_lock_irq(&logbuf_lock); | |
342 | if (count > logged_chars) | |
343 | count = logged_chars; | |
344 | if (do_clear) | |
345 | logged_chars = 0; | |
346 | limit = log_end; | |
347 | /* | |
348 | * __put_user() could sleep, and while we sleep | |
40dc5651 | 349 | * printk() could overwrite the messages |
1da177e4 LT |
350 | * we try to copy to user space. Therefore |
351 | * the messages are copied in reverse. <manfreds> | |
352 | */ | |
40dc5651 | 353 | for (i = 0; i < count && !error; i++) { |
1da177e4 LT |
354 | j = limit-1-i; |
355 | if (j + log_buf_len < log_end) | |
356 | break; | |
357 | c = LOG_BUF(j); | |
358 | spin_unlock_irq(&logbuf_lock); | |
359 | error = __put_user(c,&buf[count-1-i]); | |
360 | cond_resched(); | |
361 | spin_lock_irq(&logbuf_lock); | |
362 | } | |
363 | spin_unlock_irq(&logbuf_lock); | |
364 | if (error) | |
365 | break; | |
366 | error = i; | |
40dc5651 | 367 | if (i != count) { |
1da177e4 LT |
368 | int offset = count-error; |
369 | /* buffer overflow during copy, correct user buffer. */ | |
40dc5651 | 370 | for (i = 0; i < error; i++) { |
1da177e4 LT |
371 | if (__get_user(c,&buf[i+offset]) || |
372 | __put_user(c,&buf[i])) { | |
373 | error = -EFAULT; | |
374 | break; | |
375 | } | |
376 | cond_resched(); | |
377 | } | |
378 | } | |
379 | break; | |
380 | case 5: /* Clear ring buffer */ | |
381 | logged_chars = 0; | |
382 | break; | |
383 | case 6: /* Disable logging to console */ | |
1aaad49e FP |
384 | if (saved_console_loglevel == -1) |
385 | saved_console_loglevel = console_loglevel; | |
1da177e4 LT |
386 | console_loglevel = minimum_console_loglevel; |
387 | break; | |
388 | case 7: /* Enable logging to console */ | |
1aaad49e FP |
389 | if (saved_console_loglevel != -1) { |
390 | console_loglevel = saved_console_loglevel; | |
391 | saved_console_loglevel = -1; | |
392 | } | |
1da177e4 LT |
393 | break; |
394 | case 8: /* Set level of messages printed to console */ | |
395 | error = -EINVAL; | |
396 | if (len < 1 || len > 8) | |
397 | goto out; | |
398 | if (len < minimum_console_loglevel) | |
399 | len = minimum_console_loglevel; | |
400 | console_loglevel = len; | |
1aaad49e FP |
401 | /* Implicitly re-enable logging to console */ |
402 | saved_console_loglevel = -1; | |
1da177e4 LT |
403 | error = 0; |
404 | break; | |
405 | case 9: /* Number of chars in the log buffer */ | |
406 | error = log_end - log_start; | |
407 | break; | |
408 | case 10: /* Size of the log buffer */ | |
409 | error = log_buf_len; | |
410 | break; | |
411 | default: | |
412 | error = -EINVAL; | |
413 | break; | |
414 | } | |
415 | out: | |
416 | return error; | |
417 | } | |
418 | ||
1e7bfb21 | 419 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 420 | { |
00234592 | 421 | return do_syslog(type, buf, len, SYSLOG_FROM_CALL); |
1da177e4 LT |
422 | } |
423 | ||
424 | /* | |
425 | * Call the console drivers on a range of log_buf | |
426 | */ | |
eed4a2ab | 427 | static void __call_console_drivers(unsigned start, unsigned end) |
1da177e4 LT |
428 | { |
429 | struct console *con; | |
430 | ||
4d091611 | 431 | for_each_console(con) { |
76a8ad29 ME |
432 | if ((con->flags & CON_ENABLED) && con->write && |
433 | (cpu_online(smp_processor_id()) || | |
434 | (con->flags & CON_ANYTIME))) | |
1da177e4 LT |
435 | con->write(con, &LOG_BUF(start), end - start); |
436 | } | |
437 | } | |
438 | ||
79290822 IM |
439 | static int __read_mostly ignore_loglevel; |
440 | ||
99eea6a1 | 441 | static int __init ignore_loglevel_setup(char *str) |
79290822 IM |
442 | { |
443 | ignore_loglevel = 1; | |
444 | printk(KERN_INFO "debug: ignoring loglevel setting.\n"); | |
445 | ||
c4772d99 | 446 | return 0; |
79290822 IM |
447 | } |
448 | ||
c4772d99 | 449 | early_param("ignore_loglevel", ignore_loglevel_setup); |
79290822 | 450 | |
1da177e4 LT |
451 | /* |
452 | * Write out chars from start to end - 1 inclusive | |
453 | */ | |
eed4a2ab DV |
454 | static void _call_console_drivers(unsigned start, |
455 | unsigned end, int msg_log_level) | |
1da177e4 | 456 | { |
79290822 | 457 | if ((msg_log_level < console_loglevel || ignore_loglevel) && |
1da177e4 LT |
458 | console_drivers && start != end) { |
459 | if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { | |
460 | /* wrapped write */ | |
461 | __call_console_drivers(start & LOG_BUF_MASK, | |
462 | log_buf_len); | |
463 | __call_console_drivers(0, end & LOG_BUF_MASK); | |
464 | } else { | |
465 | __call_console_drivers(start, end); | |
466 | } | |
467 | } | |
468 | } | |
469 | ||
470 | /* | |
471 | * Call the console drivers, asking them to write out | |
472 | * log_buf[start] to log_buf[end - 1]. | |
473 | * The console_sem must be held. | |
474 | */ | |
eed4a2ab | 475 | static void call_console_drivers(unsigned start, unsigned end) |
1da177e4 | 476 | { |
eed4a2ab | 477 | unsigned cur_index, start_print; |
1da177e4 LT |
478 | static int msg_level = -1; |
479 | ||
eed4a2ab | 480 | BUG_ON(((int)(start - end)) > 0); |
1da177e4 LT |
481 | |
482 | cur_index = start; | |
483 | start_print = start; | |
484 | while (cur_index != end) { | |
40dc5651 JJ |
485 | if (msg_level < 0 && ((end - cur_index) > 2) && |
486 | LOG_BUF(cur_index + 0) == '<' && | |
487 | LOG_BUF(cur_index + 1) >= '0' && | |
488 | LOG_BUF(cur_index + 1) <= '7' && | |
489 | LOG_BUF(cur_index + 2) == '>') { | |
1da177e4 LT |
490 | msg_level = LOG_BUF(cur_index + 1) - '0'; |
491 | cur_index += 3; | |
492 | start_print = cur_index; | |
493 | } | |
494 | while (cur_index != end) { | |
495 | char c = LOG_BUF(cur_index); | |
1da177e4 | 496 | |
40dc5651 | 497 | cur_index++; |
1da177e4 LT |
498 | if (c == '\n') { |
499 | if (msg_level < 0) { | |
500 | /* | |
501 | * printk() has already given us loglevel tags in | |
502 | * the buffer. This code is here in case the | |
503 | * log buffer has wrapped right round and scribbled | |
504 | * on those tags | |
505 | */ | |
506 | msg_level = default_message_loglevel; | |
507 | } | |
508 | _call_console_drivers(start_print, cur_index, msg_level); | |
509 | msg_level = -1; | |
510 | start_print = cur_index; | |
511 | break; | |
512 | } | |
513 | } | |
514 | } | |
515 | _call_console_drivers(start_print, end, msg_level); | |
516 | } | |
517 | ||
518 | static void emit_log_char(char c) | |
519 | { | |
520 | LOG_BUF(log_end) = c; | |
521 | log_end++; | |
522 | if (log_end - log_start > log_buf_len) | |
523 | log_start = log_end - log_buf_len; | |
524 | if (log_end - con_start > log_buf_len) | |
525 | con_start = log_end - log_buf_len; | |
526 | if (logged_chars < log_buf_len) | |
527 | logged_chars++; | |
528 | } | |
529 | ||
530 | /* | |
531 | * Zap console related locks when oopsing. Only zap at most once | |
532 | * every 10 seconds, to leave time for slow consoles to print a | |
533 | * full oops. | |
534 | */ | |
535 | static void zap_locks(void) | |
536 | { | |
537 | static unsigned long oops_timestamp; | |
538 | ||
539 | if (time_after_eq(jiffies, oops_timestamp) && | |
40dc5651 | 540 | !time_after(jiffies, oops_timestamp + 30 * HZ)) |
1da177e4 LT |
541 | return; |
542 | ||
543 | oops_timestamp = jiffies; | |
544 | ||
545 | /* If a crash is occurring, make sure we can't deadlock */ | |
546 | spin_lock_init(&logbuf_lock); | |
547 | /* And make sure that we print immediately */ | |
548 | init_MUTEX(&console_sem); | |
549 | } | |
550 | ||
551 | #if defined(CONFIG_PRINTK_TIME) | |
552 | static int printk_time = 1; | |
553 | #else | |
554 | static int printk_time = 0; | |
555 | #endif | |
e84845c4 | 556 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1da177e4 | 557 | |
76a8ad29 ME |
558 | /* Check if we have any console registered that can be called early in boot. */ |
559 | static int have_callable_console(void) | |
560 | { | |
561 | struct console *con; | |
562 | ||
4d091611 | 563 | for_each_console(con) |
76a8ad29 ME |
564 | if (con->flags & CON_ANYTIME) |
565 | return 1; | |
566 | ||
567 | return 0; | |
568 | } | |
569 | ||
ddad86c2 MW |
570 | /** |
571 | * printk - print a kernel message | |
572 | * @fmt: format string | |
573 | * | |
72fd4a35 | 574 | * This is printk(). It can be called from any context. We want it to work. |
40dc5651 | 575 | * |
1da177e4 LT |
576 | * We try to grab the console_sem. If we succeed, it's easy - we log the output and |
577 | * call the console drivers. If we fail to get the semaphore we place the output | |
578 | * into the log buffer and return. The current holder of the console_sem will | |
579 | * notice the new output in release_console_sem() and will send it to the | |
580 | * consoles before releasing the semaphore. | |
581 | * | |
582 | * One effect of this deferred printing is that code which calls printk() and | |
583 | * then changes console_loglevel may break. This is because console_loglevel | |
584 | * is inspected when the actual printing occurs. | |
ddad86c2 MW |
585 | * |
586 | * See also: | |
587 | * printf(3) | |
20036fdc AK |
588 | * |
589 | * See the vsnprintf() documentation for format string extensions over C99. | |
1da177e4 | 590 | */ |
d59745ce | 591 | |
1da177e4 LT |
592 | asmlinkage int printk(const char *fmt, ...) |
593 | { | |
594 | va_list args; | |
595 | int r; | |
596 | ||
597 | va_start(args, fmt); | |
598 | r = vprintk(fmt, args); | |
599 | va_end(args); | |
600 | ||
601 | return r; | |
602 | } | |
603 | ||
fe21773d DH |
604 | /* cpu currently holding logbuf_lock */ |
605 | static volatile unsigned int printk_cpu = UINT_MAX; | |
606 | ||
266c2e0a LT |
607 | /* |
608 | * Can we actually use the console at this time on this cpu? | |
609 | * | |
610 | * Console drivers may assume that per-cpu resources have | |
611 | * been allocated. So unless they're explicitly marked as | |
612 | * being able to cope (CON_ANYTIME) don't call them until | |
613 | * this CPU is officially up. | |
614 | */ | |
615 | static inline int can_use_console(unsigned int cpu) | |
616 | { | |
617 | return cpu_online(cpu) || have_callable_console(); | |
618 | } | |
619 | ||
620 | /* | |
621 | * Try to get console ownership to actually show the kernel | |
622 | * messages from a 'printk'. Return true (and with the | |
623 | * console_semaphore held, and 'console_locked' set) if it | |
624 | * is successful, false otherwise. | |
625 | * | |
626 | * This gets called with the 'logbuf_lock' spinlock held and | |
627 | * interrupts disabled. It should return with 'lockbuf_lock' | |
628 | * released but interrupts still disabled. | |
629 | */ | |
630 | static int acquire_console_semaphore_for_printk(unsigned int cpu) | |
631 | { | |
632 | int retval = 0; | |
633 | ||
093a07e2 LT |
634 | if (!try_acquire_console_sem()) { |
635 | retval = 1; | |
636 | ||
637 | /* | |
638 | * If we can't use the console, we need to release | |
639 | * the console semaphore by hand to avoid flushing | |
640 | * the buffer. We need to hold the console semaphore | |
641 | * in order to do this test safely. | |
642 | */ | |
643 | if (!can_use_console(cpu)) { | |
644 | console_locked = 0; | |
645 | up(&console_sem); | |
646 | retval = 0; | |
647 | } | |
648 | } | |
266c2e0a LT |
649 | printk_cpu = UINT_MAX; |
650 | spin_unlock(&logbuf_lock); | |
651 | return retval; | |
652 | } | |
3b8945e8 TH |
653 | static const char recursion_bug_msg [] = |
654 | KERN_CRIT "BUG: recent printk recursion!\n"; | |
655 | static int recursion_bug; | |
edb123e1 | 656 | static int new_text_line = 1; |
3b8945e8 | 657 | static char printk_buf[1024]; |
32a76006 | 658 | |
af91322e DY |
659 | int printk_delay_msec __read_mostly; |
660 | ||
661 | static inline void printk_delay(void) | |
662 | { | |
663 | if (unlikely(printk_delay_msec)) { | |
664 | int m = printk_delay_msec; | |
665 | ||
666 | while (m--) { | |
667 | mdelay(1); | |
668 | touch_nmi_watchdog(); | |
669 | } | |
670 | } | |
671 | } | |
672 | ||
1da177e4 LT |
673 | asmlinkage int vprintk(const char *fmt, va_list args) |
674 | { | |
32a76006 | 675 | int printed_len = 0; |
09159308 | 676 | int current_log_level = default_message_loglevel; |
ac60ad74 | 677 | unsigned long flags; |
32a76006 | 678 | int this_cpu; |
1da177e4 | 679 | char *p; |
1da177e4 | 680 | |
bfe8df3d | 681 | boot_delay_msec(); |
af91322e | 682 | printk_delay(); |
bfe8df3d | 683 | |
fe21773d | 684 | preempt_disable(); |
1da177e4 | 685 | /* This stops the holder of console_sem just where we want him */ |
1efc5da3 | 686 | raw_local_irq_save(flags); |
32a76006 IM |
687 | this_cpu = smp_processor_id(); |
688 | ||
689 | /* | |
690 | * Ouch, printk recursed into itself! | |
691 | */ | |
692 | if (unlikely(printk_cpu == this_cpu)) { | |
693 | /* | |
694 | * If a crash is occurring during printk() on this CPU, | |
695 | * then try to get the crash message out but make sure | |
696 | * we can't deadlock. Otherwise just return to avoid the | |
697 | * recursion and return - but flag the recursion so that | |
698 | * it can be printed at the next appropriate moment: | |
699 | */ | |
700 | if (!oops_in_progress) { | |
3b8945e8 | 701 | recursion_bug = 1; |
32a76006 IM |
702 | goto out_restore_irqs; |
703 | } | |
704 | zap_locks(); | |
705 | } | |
706 | ||
a0f1ccfd IM |
707 | lockdep_off(); |
708 | spin_lock(&logbuf_lock); | |
32a76006 | 709 | printk_cpu = this_cpu; |
1da177e4 | 710 | |
3b8945e8 TH |
711 | if (recursion_bug) { |
712 | recursion_bug = 0; | |
713 | strcpy(printk_buf, recursion_bug_msg); | |
26cc271d | 714 | printed_len = strlen(recursion_bug_msg); |
32a76006 | 715 | } |
1da177e4 | 716 | /* Emit the output into the temporary buffer */ |
32a76006 | 717 | printed_len += vscnprintf(printk_buf + printed_len, |
cf3680b9 | 718 | sizeof(printk_buf) - printed_len, fmt, args); |
1da177e4 | 719 | |
ac60ad74 | 720 | |
5fd29d6c LT |
721 | p = printk_buf; |
722 | ||
723 | /* Do we have a loglevel in the string? */ | |
724 | if (p[0] == '<') { | |
725 | unsigned char c = p[1]; | |
726 | if (c && p[2] == '>') { | |
727 | switch (c) { | |
728 | case '0' ... '7': /* loglevel */ | |
729 | current_log_level = c - '0'; | |
e28d7137 LT |
730 | /* Fallthrough - make sure we're on a new line */ |
731 | case 'd': /* KERN_DEFAULT */ | |
5fd29d6c LT |
732 | if (!new_text_line) { |
733 | emit_log_char('\n'); | |
734 | new_text_line = 1; | |
735 | } | |
736 | /* Fallthrough - skip the loglevel */ | |
737 | case 'c': /* KERN_CONT */ | |
738 | p += 3; | |
739 | break; | |
740 | } | |
741 | } | |
742 | } | |
743 | ||
1da177e4 LT |
744 | /* |
745 | * Copy the output into log_buf. If the caller didn't provide | |
746 | * appropriate log level tags, we insert them here | |
747 | */ | |
5fd29d6c | 748 | for ( ; *p; p++) { |
ac60ad74 | 749 | if (new_text_line) { |
ac60ad74 NA |
750 | /* Always output the token */ |
751 | emit_log_char('<'); | |
752 | emit_log_char(current_log_level + '0'); | |
753 | emit_log_char('>'); | |
754 | printed_len += 3; | |
755 | new_text_line = 0; | |
756 | ||
1da177e4 | 757 | if (printk_time) { |
ac60ad74 | 758 | /* Follow the token with the time */ |
1da177e4 LT |
759 | char tbuf[50], *tp; |
760 | unsigned tlen; | |
761 | unsigned long long t; | |
762 | unsigned long nanosec_rem; | |
763 | ||
326e96b9 | 764 | t = cpu_clock(printk_cpu); |
1da177e4 | 765 | nanosec_rem = do_div(t, 1000000000); |
ac60ad74 NA |
766 | tlen = sprintf(tbuf, "[%5lu.%06lu] ", |
767 | (unsigned long) t, | |
768 | nanosec_rem / 1000); | |
1da177e4 LT |
769 | |
770 | for (tp = tbuf; tp < tbuf + tlen; tp++) | |
771 | emit_log_char(*tp); | |
025510cd | 772 | printed_len += tlen; |
1da177e4 | 773 | } |
ac60ad74 | 774 | |
1da177e4 LT |
775 | if (!*p) |
776 | break; | |
777 | } | |
ac60ad74 | 778 | |
1da177e4 LT |
779 | emit_log_char(*p); |
780 | if (*p == '\n') | |
ac60ad74 | 781 | new_text_line = 1; |
1da177e4 LT |
782 | } |
783 | ||
266c2e0a LT |
784 | /* |
785 | * Try to acquire and then immediately release the | |
786 | * console semaphore. The release will do all the | |
787 | * actual magic (print out buffers, wake up klogd, | |
788 | * etc). | |
789 | * | |
790 | * The acquire_console_semaphore_for_printk() function | |
791 | * will release 'logbuf_lock' regardless of whether it | |
792 | * actually gets the semaphore or not. | |
793 | */ | |
794 | if (acquire_console_semaphore_for_printk(this_cpu)) | |
795 | release_console_sem(); | |
76a8ad29 | 796 | |
266c2e0a | 797 | lockdep_on(); |
32a76006 | 798 | out_restore_irqs: |
266c2e0a | 799 | raw_local_irq_restore(flags); |
76a8ad29 | 800 | |
fe21773d | 801 | preempt_enable(); |
1da177e4 LT |
802 | return printed_len; |
803 | } | |
804 | EXPORT_SYMBOL(printk); | |
805 | EXPORT_SYMBOL(vprintk); | |
806 | ||
d59745ce MM |
807 | #else |
808 | ||
eed4a2ab | 809 | static void call_console_drivers(unsigned start, unsigned end) |
40dc5651 JJ |
810 | { |
811 | } | |
d59745ce MM |
812 | |
813 | #endif | |
814 | ||
f7511d5f ST |
815 | static int __add_preferred_console(char *name, int idx, char *options, |
816 | char *brl_options) | |
817 | { | |
818 | struct console_cmdline *c; | |
819 | int i; | |
820 | ||
821 | /* | |
822 | * See if this tty is not yet registered, and | |
823 | * if we have a slot free. | |
824 | */ | |
825 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
826 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
827 | console_cmdline[i].index == idx) { | |
828 | if (!brl_options) | |
829 | selected_console = i; | |
830 | return 0; | |
831 | } | |
832 | if (i == MAX_CMDLINECONSOLES) | |
833 | return -E2BIG; | |
834 | if (!brl_options) | |
835 | selected_console = i; | |
836 | c = &console_cmdline[i]; | |
837 | strlcpy(c->name, name, sizeof(c->name)); | |
838 | c->options = options; | |
839 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE | |
840 | c->brl_options = brl_options; | |
841 | #endif | |
842 | c->index = idx; | |
843 | return 0; | |
844 | } | |
2ea1c539 JB |
845 | /* |
846 | * Set up a list of consoles. Called from init/main.c | |
847 | */ | |
848 | static int __init console_setup(char *str) | |
849 | { | |
eaa944af | 850 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */ |
f7511d5f | 851 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
852 | int idx; |
853 | ||
f7511d5f ST |
854 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
855 | if (!memcmp(str, "brl,", 4)) { | |
856 | brl_options = ""; | |
857 | str += 4; | |
858 | } else if (!memcmp(str, "brl=", 4)) { | |
859 | brl_options = str + 4; | |
860 | str = strchr(brl_options, ','); | |
861 | if (!str) { | |
862 | printk(KERN_ERR "need port name after brl=\n"); | |
863 | return 1; | |
864 | } | |
865 | *(str++) = 0; | |
866 | } | |
867 | #endif | |
868 | ||
2ea1c539 JB |
869 | /* |
870 | * Decode str into name, index, options. | |
871 | */ | |
872 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
873 | strcpy(buf, "ttyS"); |
874 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 875 | } else { |
eaa944af | 876 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 877 | } |
eaa944af | 878 | buf[sizeof(buf) - 1] = 0; |
2ea1c539 JB |
879 | if ((options = strchr(str, ',')) != NULL) |
880 | *(options++) = 0; | |
881 | #ifdef __sparc__ | |
882 | if (!strcmp(str, "ttya")) | |
eaa944af | 883 | strcpy(buf, "ttyS0"); |
2ea1c539 | 884 | if (!strcmp(str, "ttyb")) |
eaa944af | 885 | strcpy(buf, "ttyS1"); |
2ea1c539 | 886 | #endif |
eaa944af | 887 | for (s = buf; *s; s++) |
2ea1c539 JB |
888 | if ((*s >= '0' && *s <= '9') || *s == ',') |
889 | break; | |
890 | idx = simple_strtoul(s, NULL, 10); | |
891 | *s = 0; | |
892 | ||
f7511d5f | 893 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 894 | console_set_on_cmdline = 1; |
2ea1c539 JB |
895 | return 1; |
896 | } | |
897 | __setup("console=", console_setup); | |
898 | ||
3c0547ba MM |
899 | /** |
900 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
901 | * @name: device name |
902 | * @idx: device index | |
903 | * @options: options for this console | |
3c0547ba MM |
904 | * |
905 | * The last preferred console added will be used for kernel messages | |
906 | * and stdin/out/err for init. Normally this is used by console_setup | |
907 | * above to handle user-supplied console arguments; however it can also | |
908 | * be used by arch-specific code either to override the user or more | |
909 | * commonly to provide a default console (ie from PROM variables) when | |
910 | * the user has not supplied one. | |
911 | */ | |
fb445ee5 | 912 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 913 | { |
f7511d5f | 914 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
915 | } |
916 | ||
b6b1d877 | 917 | int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options) |
18a8bd94 YL |
918 | { |
919 | struct console_cmdline *c; | |
920 | int i; | |
921 | ||
922 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) | |
923 | if (strcmp(console_cmdline[i].name, name) == 0 && | |
924 | console_cmdline[i].index == idx) { | |
925 | c = &console_cmdline[i]; | |
f735295b | 926 | strlcpy(c->name, name_new, sizeof(c->name)); |
18a8bd94 YL |
927 | c->name[sizeof(c->name) - 1] = 0; |
928 | c->options = options; | |
929 | c->index = idx_new; | |
930 | return i; | |
931 | } | |
932 | /* not found */ | |
933 | return -1; | |
934 | } | |
935 | ||
8f4ce8c3 AS |
936 | int console_suspend_enabled = 1; |
937 | EXPORT_SYMBOL(console_suspend_enabled); | |
938 | ||
939 | static int __init console_suspend_disable(char *str) | |
940 | { | |
941 | console_suspend_enabled = 0; | |
942 | return 1; | |
943 | } | |
944 | __setup("no_console_suspend", console_suspend_disable); | |
945 | ||
557240b4 LT |
946 | /** |
947 | * suspend_console - suspend the console subsystem | |
948 | * | |
949 | * This disables printk() while we go into suspend states | |
950 | */ | |
951 | void suspend_console(void) | |
952 | { | |
8f4ce8c3 AS |
953 | if (!console_suspend_enabled) |
954 | return; | |
0d63081d | 955 | printk("Suspending console(s) (use no_console_suspend to debug)\n"); |
557240b4 LT |
956 | acquire_console_sem(); |
957 | console_suspended = 1; | |
403f3075 | 958 | up(&console_sem); |
557240b4 LT |
959 | } |
960 | ||
961 | void resume_console(void) | |
962 | { | |
8f4ce8c3 AS |
963 | if (!console_suspend_enabled) |
964 | return; | |
403f3075 | 965 | down(&console_sem); |
557240b4 LT |
966 | console_suspended = 0; |
967 | release_console_sem(); | |
968 | } | |
969 | ||
1da177e4 LT |
970 | /** |
971 | * acquire_console_sem - lock the console system for exclusive use. | |
972 | * | |
973 | * Acquires a semaphore which guarantees that the caller has | |
974 | * exclusive access to the console system and the console_drivers list. | |
975 | * | |
976 | * Can sleep, returns nothing. | |
977 | */ | |
978 | void acquire_console_sem(void) | |
979 | { | |
8abd8e29 | 980 | BUG_ON(in_interrupt()); |
1da177e4 | 981 | down(&console_sem); |
403f3075 AH |
982 | if (console_suspended) |
983 | return; | |
1da177e4 LT |
984 | console_locked = 1; |
985 | console_may_schedule = 1; | |
986 | } | |
987 | EXPORT_SYMBOL(acquire_console_sem); | |
988 | ||
989 | int try_acquire_console_sem(void) | |
990 | { | |
991 | if (down_trylock(&console_sem)) | |
992 | return -1; | |
403f3075 AH |
993 | if (console_suspended) { |
994 | up(&console_sem); | |
995 | return -1; | |
996 | } | |
1da177e4 LT |
997 | console_locked = 1; |
998 | console_may_schedule = 0; | |
999 | return 0; | |
1000 | } | |
1001 | EXPORT_SYMBOL(try_acquire_console_sem); | |
1002 | ||
1003 | int is_console_locked(void) | |
1004 | { | |
1005 | return console_locked; | |
1006 | } | |
1da177e4 | 1007 | |
b845b517 PZ |
1008 | static DEFINE_PER_CPU(int, printk_pending); |
1009 | ||
1010 | void printk_tick(void) | |
e3e8a75d | 1011 | { |
b845b517 PZ |
1012 | if (__get_cpu_var(printk_pending)) { |
1013 | __get_cpu_var(printk_pending) = 0; | |
e3e8a75d | 1014 | wake_up_interruptible(&log_wait); |
b845b517 PZ |
1015 | } |
1016 | } | |
1017 | ||
1018 | int printk_needs_cpu(int cpu) | |
1019 | { | |
1020 | return per_cpu(printk_pending, cpu); | |
1021 | } | |
1022 | ||
1023 | void wake_up_klogd(void) | |
1024 | { | |
1025 | if (waitqueue_active(&log_wait)) | |
fa33507a | 1026 | __raw_get_cpu_var(printk_pending) = 1; |
e3e8a75d KK |
1027 | } |
1028 | ||
1da177e4 LT |
1029 | /** |
1030 | * release_console_sem - unlock the console system | |
1031 | * | |
1032 | * Releases the semaphore which the caller holds on the console system | |
1033 | * and the console driver list. | |
1034 | * | |
1035 | * While the semaphore was held, console output may have been buffered | |
1036 | * by printk(). If this is the case, release_console_sem() emits | |
1037 | * the output prior to releasing the semaphore. | |
1038 | * | |
1039 | * If there is output waiting for klogd, we wake it up. | |
1040 | * | |
1041 | * release_console_sem() may be called from any context. | |
1042 | */ | |
1043 | void release_console_sem(void) | |
1044 | { | |
1045 | unsigned long flags; | |
eed4a2ab DV |
1046 | unsigned _con_start, _log_end; |
1047 | unsigned wake_klogd = 0; | |
1da177e4 | 1048 | |
557240b4 | 1049 | if (console_suspended) { |
403f3075 | 1050 | up(&console_sem); |
557240b4 LT |
1051 | return; |
1052 | } | |
78944e54 AD |
1053 | |
1054 | console_may_schedule = 0; | |
1055 | ||
1da177e4 LT |
1056 | for ( ; ; ) { |
1057 | spin_lock_irqsave(&logbuf_lock, flags); | |
1058 | wake_klogd |= log_start - log_end; | |
1059 | if (con_start == log_end) | |
1060 | break; /* Nothing to print */ | |
1061 | _con_start = con_start; | |
1062 | _log_end = log_end; | |
1063 | con_start = log_end; /* Flush */ | |
1064 | spin_unlock(&logbuf_lock); | |
81d68a96 | 1065 | stop_critical_timings(); /* don't trace print latency */ |
1da177e4 | 1066 | call_console_drivers(_con_start, _log_end); |
81d68a96 | 1067 | start_critical_timings(); |
1da177e4 LT |
1068 | local_irq_restore(flags); |
1069 | } | |
1070 | console_locked = 0; | |
1da177e4 LT |
1071 | up(&console_sem); |
1072 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
e3e8a75d KK |
1073 | if (wake_klogd) |
1074 | wake_up_klogd(); | |
1da177e4 LT |
1075 | } |
1076 | EXPORT_SYMBOL(release_console_sem); | |
1077 | ||
ddad86c2 MW |
1078 | /** |
1079 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
1080 | * |
1081 | * If the console code is currently allowed to sleep, and | |
1082 | * if this CPU should yield the CPU to another task, do | |
1083 | * so here. | |
1084 | * | |
1085 | * Must be called within acquire_console_sem(). | |
1086 | */ | |
1087 | void __sched console_conditional_schedule(void) | |
1088 | { | |
1089 | if (console_may_schedule) | |
1090 | cond_resched(); | |
1091 | } | |
1092 | EXPORT_SYMBOL(console_conditional_schedule); | |
1093 | ||
1da177e4 LT |
1094 | void console_unblank(void) |
1095 | { | |
1096 | struct console *c; | |
1097 | ||
1098 | /* | |
1099 | * console_unblank can no longer be called in interrupt context unless | |
1100 | * oops_in_progress is set to 1.. | |
1101 | */ | |
1102 | if (oops_in_progress) { | |
1103 | if (down_trylock(&console_sem) != 0) | |
1104 | return; | |
1105 | } else | |
1106 | acquire_console_sem(); | |
1107 | ||
1108 | console_locked = 1; | |
1109 | console_may_schedule = 0; | |
4d091611 | 1110 | for_each_console(c) |
1da177e4 LT |
1111 | if ((c->flags & CON_ENABLED) && c->unblank) |
1112 | c->unblank(); | |
1113 | release_console_sem(); | |
1114 | } | |
1da177e4 LT |
1115 | |
1116 | /* | |
1117 | * Return the console tty driver structure and its associated index | |
1118 | */ | |
1119 | struct tty_driver *console_device(int *index) | |
1120 | { | |
1121 | struct console *c; | |
1122 | struct tty_driver *driver = NULL; | |
1123 | ||
1124 | acquire_console_sem(); | |
4d091611 | 1125 | for_each_console(c) { |
1da177e4 LT |
1126 | if (!c->device) |
1127 | continue; | |
1128 | driver = c->device(c, index); | |
1129 | if (driver) | |
1130 | break; | |
1131 | } | |
1132 | release_console_sem(); | |
1133 | return driver; | |
1134 | } | |
1135 | ||
1136 | /* | |
1137 | * Prevent further output on the passed console device so that (for example) | |
1138 | * serial drivers can disable console output before suspending a port, and can | |
1139 | * re-enable output afterwards. | |
1140 | */ | |
1141 | void console_stop(struct console *console) | |
1142 | { | |
1143 | acquire_console_sem(); | |
1144 | console->flags &= ~CON_ENABLED; | |
1145 | release_console_sem(); | |
1146 | } | |
1147 | EXPORT_SYMBOL(console_stop); | |
1148 | ||
1149 | void console_start(struct console *console) | |
1150 | { | |
1151 | acquire_console_sem(); | |
1152 | console->flags |= CON_ENABLED; | |
1153 | release_console_sem(); | |
1154 | } | |
1155 | EXPORT_SYMBOL(console_start); | |
1156 | ||
1157 | /* | |
1158 | * The console driver calls this routine during kernel initialization | |
1159 | * to register the console printing procedure with printk() and to | |
1160 | * print any messages that were printed by the kernel before the | |
1161 | * console driver was initialized. | |
4d091611 RG |
1162 | * |
1163 | * This can happen pretty early during the boot process (because of | |
1164 | * early_printk) - sometimes before setup_arch() completes - be careful | |
1165 | * of what kernel features are used - they may not be initialised yet. | |
1166 | * | |
1167 | * There are two types of consoles - bootconsoles (early_printk) and | |
1168 | * "real" consoles (everything which is not a bootconsole) which are | |
1169 | * handled differently. | |
1170 | * - Any number of bootconsoles can be registered at any time. | |
1171 | * - As soon as a "real" console is registered, all bootconsoles | |
1172 | * will be unregistered automatically. | |
1173 | * - Once a "real" console is registered, any attempt to register a | |
1174 | * bootconsoles will be rejected | |
1da177e4 | 1175 | */ |
4d091611 | 1176 | void register_console(struct console *newcon) |
1da177e4 | 1177 | { |
40dc5651 | 1178 | int i; |
1da177e4 | 1179 | unsigned long flags; |
4d091611 | 1180 | struct console *bcon = NULL; |
1da177e4 | 1181 | |
4d091611 RG |
1182 | /* |
1183 | * before we register a new CON_BOOT console, make sure we don't | |
1184 | * already have a valid console | |
1185 | */ | |
1186 | if (console_drivers && newcon->flags & CON_BOOT) { | |
1187 | /* find the last or real console */ | |
1188 | for_each_console(bcon) { | |
1189 | if (!(bcon->flags & CON_BOOT)) { | |
1190 | printk(KERN_INFO "Too late to register bootconsole %s%d\n", | |
1191 | newcon->name, newcon->index); | |
1192 | return; | |
1193 | } | |
1194 | } | |
69331af7 GH |
1195 | } |
1196 | ||
4d091611 RG |
1197 | if (console_drivers && console_drivers->flags & CON_BOOT) |
1198 | bcon = console_drivers; | |
1199 | ||
1200 | if (preferred_console < 0 || bcon || !console_drivers) | |
1da177e4 LT |
1201 | preferred_console = selected_console; |
1202 | ||
4d091611 RG |
1203 | if (newcon->early_setup) |
1204 | newcon->early_setup(); | |
18a8bd94 | 1205 | |
1da177e4 LT |
1206 | /* |
1207 | * See if we want to use this console driver. If we | |
1208 | * didn't select a console we take the first one | |
1209 | * that registers here. | |
1210 | */ | |
1211 | if (preferred_console < 0) { | |
4d091611 RG |
1212 | if (newcon->index < 0) |
1213 | newcon->index = 0; | |
1214 | if (newcon->setup == NULL || | |
1215 | newcon->setup(newcon, NULL) == 0) { | |
1216 | newcon->flags |= CON_ENABLED; | |
1217 | if (newcon->device) { | |
1218 | newcon->flags |= CON_CONSDEV; | |
cd3a1b85 JK |
1219 | preferred_console = 0; |
1220 | } | |
1da177e4 LT |
1221 | } |
1222 | } | |
1223 | ||
1224 | /* | |
1225 | * See if this console matches one we selected on | |
1226 | * the command line. | |
1227 | */ | |
40dc5651 JJ |
1228 | for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; |
1229 | i++) { | |
4d091611 | 1230 | if (strcmp(console_cmdline[i].name, newcon->name) != 0) |
1da177e4 | 1231 | continue; |
4d091611 RG |
1232 | if (newcon->index >= 0 && |
1233 | newcon->index != console_cmdline[i].index) | |
1da177e4 | 1234 | continue; |
4d091611 RG |
1235 | if (newcon->index < 0) |
1236 | newcon->index = console_cmdline[i].index; | |
f7511d5f ST |
1237 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1238 | if (console_cmdline[i].brl_options) { | |
4d091611 RG |
1239 | newcon->flags |= CON_BRL; |
1240 | braille_register_console(newcon, | |
f7511d5f ST |
1241 | console_cmdline[i].index, |
1242 | console_cmdline[i].options, | |
1243 | console_cmdline[i].brl_options); | |
1244 | return; | |
1245 | } | |
1246 | #endif | |
4d091611 RG |
1247 | if (newcon->setup && |
1248 | newcon->setup(newcon, console_cmdline[i].options) != 0) | |
1da177e4 | 1249 | break; |
4d091611 RG |
1250 | newcon->flags |= CON_ENABLED; |
1251 | newcon->index = console_cmdline[i].index; | |
ab4af03a | 1252 | if (i == selected_console) { |
4d091611 | 1253 | newcon->flags |= CON_CONSDEV; |
ab4af03a GE |
1254 | preferred_console = selected_console; |
1255 | } | |
1da177e4 LT |
1256 | break; |
1257 | } | |
1258 | ||
4d091611 | 1259 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
1260 | return; |
1261 | ||
8259cf43 RG |
1262 | /* |
1263 | * If we have a bootconsole, and are switching to a real console, | |
1264 | * don't print everything out again, since when the boot console, and | |
1265 | * the real console are the same physical device, it's annoying to | |
1266 | * see the beginning boot messages twice | |
1267 | */ | |
1268 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 1269 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
1270 | |
1271 | /* | |
1272 | * Put this console in the list - keep the | |
1273 | * preferred driver at the head of the list. | |
1274 | */ | |
1275 | acquire_console_sem(); | |
4d091611 RG |
1276 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
1277 | newcon->next = console_drivers; | |
1278 | console_drivers = newcon; | |
1279 | if (newcon->next) | |
1280 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 1281 | } else { |
4d091611 RG |
1282 | newcon->next = console_drivers->next; |
1283 | console_drivers->next = newcon; | |
1da177e4 | 1284 | } |
4d091611 | 1285 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 LT |
1286 | /* |
1287 | * release_console_sem() will print out the buffered messages | |
1288 | * for us. | |
1289 | */ | |
1290 | spin_lock_irqsave(&logbuf_lock, flags); | |
1291 | con_start = log_start; | |
1292 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1293 | } | |
1294 | release_console_sem(); | |
8259cf43 RG |
1295 | |
1296 | /* | |
1297 | * By unregistering the bootconsoles after we enable the real console | |
1298 | * we get the "console xxx enabled" message on all the consoles - | |
1299 | * boot consoles, real consoles, etc - this is to ensure that end | |
1300 | * users know there might be something in the kernel's log buffer that | |
1301 | * went to the bootconsole (that they do not see on the real console) | |
1302 | */ | |
1303 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) { | |
1304 | /* we need to iterate through twice, to make sure we print | |
1305 | * everything out, before we unregister the console(s) | |
1306 | */ | |
1307 | printk(KERN_INFO "console [%s%d] enabled, bootconsole disabled\n", | |
1308 | newcon->name, newcon->index); | |
1309 | for_each_console(bcon) | |
1310 | if (bcon->flags & CON_BOOT) | |
1311 | unregister_console(bcon); | |
1312 | } else { | |
1313 | printk(KERN_INFO "%sconsole [%s%d] enabled\n", | |
1314 | (newcon->flags & CON_BOOT) ? "boot" : "" , | |
1315 | newcon->name, newcon->index); | |
1316 | } | |
1da177e4 LT |
1317 | } |
1318 | EXPORT_SYMBOL(register_console); | |
1319 | ||
40dc5651 | 1320 | int unregister_console(struct console *console) |
1da177e4 | 1321 | { |
40dc5651 | 1322 | struct console *a, *b; |
1da177e4 LT |
1323 | int res = 1; |
1324 | ||
f7511d5f ST |
1325 | #ifdef CONFIG_A11Y_BRAILLE_CONSOLE |
1326 | if (console->flags & CON_BRL) | |
1327 | return braille_unregister_console(console); | |
1328 | #endif | |
1329 | ||
1da177e4 LT |
1330 | acquire_console_sem(); |
1331 | if (console_drivers == console) { | |
1332 | console_drivers=console->next; | |
1333 | res = 0; | |
e9b15b54 | 1334 | } else if (console_drivers) { |
1da177e4 LT |
1335 | for (a=console_drivers->next, b=console_drivers ; |
1336 | a; b=a, a=b->next) { | |
1337 | if (a == console) { | |
1338 | b->next = a->next; | |
1339 | res = 0; | |
1340 | break; | |
40dc5651 | 1341 | } |
1da177e4 LT |
1342 | } |
1343 | } | |
40dc5651 | 1344 | |
69331af7 | 1345 | /* |
ab4af03a GE |
1346 | * If this isn't the last console and it has CON_CONSDEV set, we |
1347 | * need to set it on the next preferred console. | |
1da177e4 | 1348 | */ |
69331af7 | 1349 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 1350 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 LT |
1351 | |
1352 | release_console_sem(); | |
1353 | return res; | |
1354 | } | |
1355 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 1356 | |
0c5564bd RG |
1357 | static int __init disable_boot_consoles(void) |
1358 | { | |
4d091611 RG |
1359 | struct console *con; |
1360 | ||
1361 | for_each_console(con) { | |
1362 | if (con->flags & CON_BOOT) { | |
cb00e99c | 1363 | printk(KERN_INFO "turn off boot console %s%d\n", |
4d091611 | 1364 | con->name, con->index); |
42c2c8c8 | 1365 | unregister_console(con); |
cb00e99c | 1366 | } |
0c5564bd RG |
1367 | } |
1368 | return 0; | |
1369 | } | |
1370 | late_initcall(disable_boot_consoles); | |
1371 | ||
7ef3d2fd | 1372 | #if defined CONFIG_PRINTK |
717115e1 | 1373 | |
1da177e4 LT |
1374 | /* |
1375 | * printk rate limiting, lifted from the networking subsystem. | |
1376 | * | |
641de9d8 UKK |
1377 | * This enforces a rate limit: not more than 10 kernel messages |
1378 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 1379 | */ |
641de9d8 UKK |
1380 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
1381 | ||
5c828713 | 1382 | int __printk_ratelimit(const char *func) |
1da177e4 | 1383 | { |
5c828713 | 1384 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 1385 | } |
5c828713 | 1386 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
1387 | |
1388 | /** | |
1389 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
1390 | * @caller_jiffies: pointer to caller's state | |
1391 | * @interval_msecs: minimum interval between prints | |
1392 | * | |
1393 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
1394 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
1395 | * returned true. | |
1396 | */ | |
1397 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
1398 | unsigned int interval_msecs) | |
1399 | { | |
f2d28a2e GK |
1400 | if (*caller_jiffies == 0 |
1401 | || !time_in_range(jiffies, *caller_jiffies, | |
1402 | *caller_jiffies | |
1403 | + msecs_to_jiffies(interval_msecs))) { | |
1404 | *caller_jiffies = jiffies; | |
f46c4833 AM |
1405 | return true; |
1406 | } | |
1407 | return false; | |
1408 | } | |
1409 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
1410 | |
1411 | static DEFINE_SPINLOCK(dump_list_lock); | |
1412 | static LIST_HEAD(dump_list); | |
1413 | ||
1414 | /** | |
1415 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 1416 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1417 | * |
1418 | * Adds a kernel log dumper to the system. The dump callback in the | |
1419 | * structure will be called when the kernel oopses or panics and must be | |
1420 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
1421 | */ | |
1422 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
1423 | { | |
1424 | unsigned long flags; | |
1425 | int err = -EBUSY; | |
1426 | ||
1427 | /* The dump callback needs to be set */ | |
1428 | if (!dumper->dump) | |
1429 | return -EINVAL; | |
1430 | ||
1431 | spin_lock_irqsave(&dump_list_lock, flags); | |
1432 | /* Don't allow registering multiple times */ | |
1433 | if (!dumper->registered) { | |
1434 | dumper->registered = 1; | |
1435 | list_add_tail(&dumper->list, &dump_list); | |
1436 | err = 0; | |
1437 | } | |
1438 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1439 | ||
1440 | return err; | |
1441 | } | |
1442 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
1443 | ||
1444 | /** | |
1445 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 1446 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
1447 | * |
1448 | * Removes a dump device from the system. Returns zero on success and | |
1449 | * %-EINVAL otherwise. | |
1450 | */ | |
1451 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
1452 | { | |
1453 | unsigned long flags; | |
1454 | int err = -EINVAL; | |
1455 | ||
1456 | spin_lock_irqsave(&dump_list_lock, flags); | |
1457 | if (dumper->registered) { | |
1458 | dumper->registered = 0; | |
1459 | list_del(&dumper->list); | |
1460 | err = 0; | |
1461 | } | |
1462 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1463 | ||
1464 | return err; | |
1465 | } | |
1466 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
1467 | ||
1468 | static const char const *kmsg_reasons[] = { | |
1469 | [KMSG_DUMP_OOPS] = "oops", | |
1470 | [KMSG_DUMP_PANIC] = "panic", | |
1471 | }; | |
1472 | ||
1473 | static const char *kmsg_to_str(enum kmsg_dump_reason reason) | |
1474 | { | |
1475 | if (reason >= ARRAY_SIZE(kmsg_reasons) || reason < 0) | |
1476 | return "unknown"; | |
1477 | ||
1478 | return kmsg_reasons[reason]; | |
1479 | } | |
1480 | ||
1481 | /** | |
1482 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
1483 | * @reason: the reason (oops, panic etc) for dumping | |
1484 | * | |
1485 | * Iterate through each of the dump devices and call the oops/panic | |
1486 | * callbacks with the log buffer. | |
1487 | */ | |
1488 | void kmsg_dump(enum kmsg_dump_reason reason) | |
1489 | { | |
1490 | unsigned long end; | |
1491 | unsigned chars; | |
1492 | struct kmsg_dumper *dumper; | |
1493 | const char *s1, *s2; | |
1494 | unsigned long l1, l2; | |
1495 | unsigned long flags; | |
1496 | ||
1497 | /* Theoretically, the log could move on after we do this, but | |
1498 | there's not a lot we can do about that. The new messages | |
1499 | will overwrite the start of what we dump. */ | |
1500 | spin_lock_irqsave(&logbuf_lock, flags); | |
1501 | end = log_end & LOG_BUF_MASK; | |
1502 | chars = logged_chars; | |
1503 | spin_unlock_irqrestore(&logbuf_lock, flags); | |
1504 | ||
1505 | if (logged_chars > end) { | |
1506 | s1 = log_buf + log_buf_len - logged_chars + end; | |
1507 | l1 = logged_chars - end; | |
1508 | ||
1509 | s2 = log_buf; | |
1510 | l2 = end; | |
1511 | } else { | |
1512 | s1 = ""; | |
1513 | l1 = 0; | |
1514 | ||
1515 | s2 = log_buf + end - logged_chars; | |
1516 | l2 = logged_chars; | |
1517 | } | |
1518 | ||
1519 | if (!spin_trylock_irqsave(&dump_list_lock, flags)) { | |
1520 | printk(KERN_ERR "dump_kmsg: dump list lock is held during %s, skipping dump\n", | |
1521 | kmsg_to_str(reason)); | |
1522 | return; | |
1523 | } | |
1524 | list_for_each_entry(dumper, &dump_list, list) | |
1525 | dumper->dump(dumper, reason, s1, l1, s2, l2); | |
1526 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
1527 | } | |
7ef3d2fd | 1528 | #endif |