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 | ||
dd5adbfb HZ |
19 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
20 | ||
1da177e4 LT |
21 | #include <linux/kernel.h> |
22 | #include <linux/mm.h> | |
23 | #include <linux/tty.h> | |
24 | #include <linux/tty_driver.h> | |
1da177e4 LT |
25 | #include <linux/console.h> |
26 | #include <linux/init.h> | |
bfe8df3d RD |
27 | #include <linux/jiffies.h> |
28 | #include <linux/nmi.h> | |
1da177e4 | 29 | #include <linux/module.h> |
3b9c0410 | 30 | #include <linux/moduleparam.h> |
1da177e4 LT |
31 | #include <linux/delay.h> |
32 | #include <linux/smp.h> | |
33 | #include <linux/security.h> | |
162a7e75 | 34 | #include <linux/memblock.h> |
1da177e4 | 35 | #include <linux/syscalls.h> |
692f66f2 | 36 | #include <linux/crash_core.h> |
d37d39ae | 37 | #include <linux/kdb.h> |
3fff4c42 | 38 | #include <linux/ratelimit.h> |
456b565c | 39 | #include <linux/kmsg_dump.h> |
00234592 | 40 | #include <linux/syslog.h> |
034260d6 | 41 | #include <linux/cpu.h> |
fb842b00 | 42 | #include <linux/rculist.h> |
e11fea92 | 43 | #include <linux/poll.h> |
74876a98 | 44 | #include <linux/irq_work.h> |
249771b8 | 45 | #include <linux/ctype.h> |
e2e40f2c | 46 | #include <linux/uio.h> |
e6017571 | 47 | #include <linux/sched/clock.h> |
b17b0153 | 48 | #include <linux/sched/debug.h> |
68db0cf1 | 49 | #include <linux/sched/task_stack.h> |
1da177e4 | 50 | |
7c0f6ba6 | 51 | #include <linux/uaccess.h> |
40a7d9f5 | 52 | #include <asm/sections.h> |
1da177e4 | 53 | |
58eacfff | 54 | #include <trace/events/initcall.h> |
95100358 JB |
55 | #define CREATE_TRACE_POINTS |
56 | #include <trace/events/printk.h> | |
57 | ||
d197c43d | 58 | #include "console_cmdline.h" |
bbeddf52 | 59 | #include "braille.h" |
42a0bb3f | 60 | #include "internal.h" |
d197c43d | 61 | |
1da177e4 | 62 | int console_printk[4] = { |
a8fe19eb | 63 | CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */ |
42a9dc0b | 64 | MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */ |
a8fe19eb BP |
65 | CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */ |
66 | CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ | |
1da177e4 LT |
67 | }; |
68 | ||
56e6c104 TZ |
69 | atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0); |
70 | EXPORT_SYMBOL(ignore_console_lock_warning); | |
71 | ||
1da177e4 | 72 | /* |
0bbfb7c2 | 73 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
74 | * their unblank() callback or not. So let's export it. |
75 | */ | |
76 | int oops_in_progress; | |
77 | EXPORT_SYMBOL(oops_in_progress); | |
78 | ||
79 | /* | |
80 | * console_sem protects the console_drivers list, and also | |
81 | * provides serialisation for access to the entire console | |
82 | * driver system. | |
83 | */ | |
5b8c4f23 | 84 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 85 | struct console *console_drivers; |
a29d1cfe IM |
86 | EXPORT_SYMBOL_GPL(console_drivers); |
87 | ||
daee7797 DV |
88 | #ifdef CONFIG_LOCKDEP |
89 | static struct lockdep_map console_lock_dep_map = { | |
90 | .name = "console_lock" | |
91 | }; | |
92 | #endif | |
93 | ||
750afe7b BP |
94 | enum devkmsg_log_bits { |
95 | __DEVKMSG_LOG_BIT_ON = 0, | |
96 | __DEVKMSG_LOG_BIT_OFF, | |
97 | __DEVKMSG_LOG_BIT_LOCK, | |
98 | }; | |
99 | ||
100 | enum devkmsg_log_masks { | |
101 | DEVKMSG_LOG_MASK_ON = BIT(__DEVKMSG_LOG_BIT_ON), | |
102 | DEVKMSG_LOG_MASK_OFF = BIT(__DEVKMSG_LOG_BIT_OFF), | |
103 | DEVKMSG_LOG_MASK_LOCK = BIT(__DEVKMSG_LOG_BIT_LOCK), | |
104 | }; | |
105 | ||
106 | /* Keep both the 'on' and 'off' bits clear, i.e. ratelimit by default: */ | |
107 | #define DEVKMSG_LOG_MASK_DEFAULT 0 | |
108 | ||
109 | static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; | |
110 | ||
111 | static int __control_devkmsg(char *str) | |
112 | { | |
113 | if (!str) | |
114 | return -EINVAL; | |
115 | ||
116 | if (!strncmp(str, "on", 2)) { | |
117 | devkmsg_log = DEVKMSG_LOG_MASK_ON; | |
118 | return 2; | |
119 | } else if (!strncmp(str, "off", 3)) { | |
120 | devkmsg_log = DEVKMSG_LOG_MASK_OFF; | |
121 | return 3; | |
122 | } else if (!strncmp(str, "ratelimit", 9)) { | |
123 | devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; | |
124 | return 9; | |
125 | } | |
126 | return -EINVAL; | |
127 | } | |
128 | ||
129 | static int __init control_devkmsg(char *str) | |
130 | { | |
131 | if (__control_devkmsg(str) < 0) | |
132 | return 1; | |
133 | ||
134 | /* | |
135 | * Set sysctl string accordingly: | |
136 | */ | |
6fd78a1a SS |
137 | if (devkmsg_log == DEVKMSG_LOG_MASK_ON) |
138 | strcpy(devkmsg_log_str, "on"); | |
139 | else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF) | |
140 | strcpy(devkmsg_log_str, "off"); | |
750afe7b BP |
141 | /* else "ratelimit" which is set by default. */ |
142 | ||
143 | /* | |
144 | * Sysctl cannot change it anymore. The kernel command line setting of | |
145 | * this parameter is to force the setting to be permanent throughout the | |
146 | * runtime of the system. This is a precation measure against userspace | |
147 | * trying to be a smarta** and attempting to change it up on us. | |
148 | */ | |
149 | devkmsg_log |= DEVKMSG_LOG_MASK_LOCK; | |
150 | ||
151 | return 0; | |
152 | } | |
153 | __setup("printk.devkmsg=", control_devkmsg); | |
154 | ||
155 | char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit"; | |
156 | ||
157 | int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, | |
158 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
159 | { | |
160 | char old_str[DEVKMSG_STR_MAX_SIZE]; | |
161 | unsigned int old; | |
162 | int err; | |
163 | ||
164 | if (write) { | |
165 | if (devkmsg_log & DEVKMSG_LOG_MASK_LOCK) | |
166 | return -EINVAL; | |
167 | ||
168 | old = devkmsg_log; | |
169 | strncpy(old_str, devkmsg_log_str, DEVKMSG_STR_MAX_SIZE); | |
170 | } | |
171 | ||
172 | err = proc_dostring(table, write, buffer, lenp, ppos); | |
173 | if (err) | |
174 | return err; | |
175 | ||
176 | if (write) { | |
177 | err = __control_devkmsg(devkmsg_log_str); | |
178 | ||
179 | /* | |
180 | * Do not accept an unknown string OR a known string with | |
181 | * trailing crap... | |
182 | */ | |
183 | if (err < 0 || (err + 1 != *lenp)) { | |
184 | ||
185 | /* ... and restore old setting. */ | |
186 | devkmsg_log = old; | |
187 | strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE); | |
188 | ||
189 | return -EINVAL; | |
190 | } | |
191 | } | |
192 | ||
193 | return 0; | |
194 | } | |
195 | ||
9627808d | 196 | /* Number of registered extended console drivers. */ |
6fe29354 TH |
197 | static int nr_ext_console_drivers; |
198 | ||
bd8d7cf5 JK |
199 | /* |
200 | * Helper macros to handle lockdep when locking/unlocking console_sem. We use | |
201 | * macros instead of functions so that _RET_IP_ contains useful information. | |
202 | */ | |
203 | #define down_console_sem() do { \ | |
204 | down(&console_sem);\ | |
205 | mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ | |
206 | } while (0) | |
207 | ||
208 | static int __down_trylock_console_sem(unsigned long ip) | |
209 | { | |
f975237b SS |
210 | int lock_failed; |
211 | unsigned long flags; | |
212 | ||
213 | /* | |
214 | * Here and in __up_console_sem() we need to be in safe mode, | |
215 | * because spindump/WARN/etc from under console ->lock will | |
216 | * deadlock in printk()->down_trylock_console_sem() otherwise. | |
217 | */ | |
218 | printk_safe_enter_irqsave(flags); | |
219 | lock_failed = down_trylock(&console_sem); | |
220 | printk_safe_exit_irqrestore(flags); | |
221 | ||
222 | if (lock_failed) | |
bd8d7cf5 JK |
223 | return 1; |
224 | mutex_acquire(&console_lock_dep_map, 0, 1, ip); | |
225 | return 0; | |
226 | } | |
227 | #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) | |
228 | ||
f975237b SS |
229 | static void __up_console_sem(unsigned long ip) |
230 | { | |
231 | unsigned long flags; | |
232 | ||
233 | mutex_release(&console_lock_dep_map, 1, ip); | |
234 | ||
235 | printk_safe_enter_irqsave(flags); | |
236 | up(&console_sem); | |
237 | printk_safe_exit_irqrestore(flags); | |
238 | } | |
239 | #define up_console_sem() __up_console_sem(_RET_IP_) | |
bd8d7cf5 | 240 | |
1da177e4 LT |
241 | /* |
242 | * This is used for debugging the mess that is the VT code by | |
243 | * keeping track if we have the console semaphore held. It's | |
244 | * definitely not the perfect debug tool (we don't know if _WE_ | |
0b90fec3 AE |
245 | * hold it and are racing, but it helps tracking those weird code |
246 | * paths in the console code where we end up in places I want | |
247 | * locked without the console sempahore held). | |
1da177e4 | 248 | */ |
557240b4 | 249 | static int console_locked, console_suspended; |
1da177e4 | 250 | |
fe3d8ad3 FT |
251 | /* |
252 | * If exclusive_console is non-NULL then only this console is to be printed to. | |
253 | */ | |
254 | static struct console *exclusive_console; | |
255 | ||
1da177e4 LT |
256 | /* |
257 | * Array of consoles built from command line options (console=) | |
258 | */ | |
1da177e4 LT |
259 | |
260 | #define MAX_CMDLINECONSOLES 8 | |
261 | ||
262 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
d197c43d | 263 | |
1da177e4 | 264 | static int preferred_console = -1; |
9e124fe1 MA |
265 | int console_set_on_cmdline; |
266 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
267 | |
268 | /* Flag: console code may call schedule() */ | |
269 | static int console_may_schedule; | |
270 | ||
cca10d58 SS |
271 | enum con_msg_format_flags { |
272 | MSG_FORMAT_DEFAULT = 0, | |
273 | MSG_FORMAT_SYSLOG = (1 << 0), | |
274 | }; | |
275 | ||
276 | static int console_msg_format = MSG_FORMAT_DEFAULT; | |
277 | ||
7ff9554b KS |
278 | /* |
279 | * The printk log buffer consists of a chain of concatenated variable | |
280 | * length records. Every record starts with a record header, containing | |
281 | * the overall length of the record. | |
282 | * | |
283 | * The heads to the first and last entry in the buffer, as well as the | |
0b90fec3 AE |
284 | * sequence numbers of these entries are maintained when messages are |
285 | * stored. | |
7ff9554b KS |
286 | * |
287 | * If the heads indicate available messages, the length in the header | |
288 | * tells the start next message. A length == 0 for the next message | |
289 | * indicates a wrap-around to the beginning of the buffer. | |
290 | * | |
291 | * Every record carries the monotonic timestamp in microseconds, as well as | |
292 | * the standard userspace syslog level and syslog facility. The usual | |
293 | * kernel messages use LOG_KERN; userspace-injected messages always carry | |
294 | * a matching syslog facility, by default LOG_USER. The origin of every | |
295 | * message can be reliably determined that way. | |
296 | * | |
297 | * The human readable log message directly follows the message header. The | |
298 | * length of the message text is stored in the header, the stored message | |
299 | * is not terminated. | |
300 | * | |
e11fea92 KS |
301 | * Optionally, a message can carry a dictionary of properties (key/value pairs), |
302 | * to provide userspace with a machine-readable message context. | |
303 | * | |
304 | * Examples for well-defined, commonly used property names are: | |
305 | * DEVICE=b12:8 device identifier | |
306 | * b12:8 block dev_t | |
307 | * c127:3 char dev_t | |
308 | * n8 netdev ifindex | |
309 | * +sound:card0 subsystem:devname | |
310 | * SUBSYSTEM=pci driver-core subsystem name | |
311 | * | |
312 | * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value | |
313 | * follows directly after a '=' character. Every property is terminated by | |
314 | * a '\0' character. The last property is not terminated. | |
315 | * | |
316 | * Example of a message structure: | |
317 | * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec | |
318 | * 0008 34 00 record is 52 bytes long | |
319 | * 000a 0b 00 text is 11 bytes long | |
320 | * 000c 1f 00 dictionary is 23 bytes long | |
321 | * 000e 03 00 LOG_KERN (facility) LOG_ERR (level) | |
322 | * 0010 69 74 27 73 20 61 20 6c "it's a l" | |
323 | * 69 6e 65 "ine" | |
324 | * 001b 44 45 56 49 43 "DEVIC" | |
325 | * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D" | |
326 | * 52 49 56 45 52 3d 62 75 "RIVER=bu" | |
327 | * 67 "g" | |
328 | * 0032 00 00 00 padding to next message header | |
329 | * | |
62e32ac3 | 330 | * The 'struct printk_log' buffer header must never be directly exported to |
e11fea92 KS |
331 | * userspace, it is a kernel-private implementation detail that might |
332 | * need to be changed in the future, when the requirements change. | |
333 | * | |
334 | * /dev/kmsg exports the structured data in the following line format: | |
b389645f AO |
335 | * "<level>,<sequnum>,<timestamp>,<contflag>[,additional_values, ... ];<message text>\n" |
336 | * | |
337 | * Users of the export format should ignore possible additional values | |
338 | * separated by ',', and find the message after the ';' character. | |
e11fea92 KS |
339 | * |
340 | * The optional key/value pairs are attached as continuation lines starting | |
341 | * with a space character and terminated by a newline. All possible | |
342 | * non-prinatable characters are escaped in the "\xff" notation. | |
7ff9554b KS |
343 | */ |
344 | ||
084681d1 | 345 | enum log_flags { |
5becfb1d KS |
346 | LOG_NEWLINE = 2, /* text ended with a newline */ |
347 | LOG_PREFIX = 4, /* text started with a prefix */ | |
348 | LOG_CONT = 8, /* text is a fragment of a continuation line */ | |
084681d1 KS |
349 | }; |
350 | ||
62e32ac3 | 351 | struct printk_log { |
7ff9554b KS |
352 | u64 ts_nsec; /* timestamp in nanoseconds */ |
353 | u16 len; /* length of entire record */ | |
354 | u16 text_len; /* length of text buffer */ | |
355 | u16 dict_len; /* length of dictionary buffer */ | |
084681d1 KS |
356 | u8 facility; /* syslog facility */ |
357 | u8 flags:5; /* internal record flags */ | |
358 | u8 level:3; /* syslog level */ | |
5c9cf8af AR |
359 | } |
360 | #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS | |
361 | __packed __aligned(4) | |
362 | #endif | |
363 | ; | |
7ff9554b KS |
364 | |
365 | /* | |
458df9fd SR |
366 | * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken |
367 | * within the scheduler's rq lock. It must be released before calling | |
368 | * console_unlock() or anything else that might wake up a process. | |
7ff9554b | 369 | */ |
cf9b1106 | 370 | DEFINE_RAW_SPINLOCK(logbuf_lock); |
d59745ce | 371 | |
de6fcbdb SS |
372 | /* |
373 | * Helper macros to lock/unlock logbuf_lock and switch between | |
374 | * printk-safe/unsafe modes. | |
375 | */ | |
376 | #define logbuf_lock_irq() \ | |
377 | do { \ | |
378 | printk_safe_enter_irq(); \ | |
379 | raw_spin_lock(&logbuf_lock); \ | |
380 | } while (0) | |
381 | ||
382 | #define logbuf_unlock_irq() \ | |
383 | do { \ | |
384 | raw_spin_unlock(&logbuf_lock); \ | |
385 | printk_safe_exit_irq(); \ | |
386 | } while (0) | |
387 | ||
388 | #define logbuf_lock_irqsave(flags) \ | |
389 | do { \ | |
390 | printk_safe_enter_irqsave(flags); \ | |
391 | raw_spin_lock(&logbuf_lock); \ | |
392 | } while (0) | |
393 | ||
394 | #define logbuf_unlock_irqrestore(flags) \ | |
395 | do { \ | |
396 | raw_spin_unlock(&logbuf_lock); \ | |
397 | printk_safe_exit_irqrestore(flags); \ | |
398 | } while (0) | |
399 | ||
96efedf1 | 400 | #ifdef CONFIG_PRINTK |
dc72c32e | 401 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
7f3a781d KS |
402 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
403 | static u64 syslog_seq; | |
404 | static u32 syslog_idx; | |
eb02dac9 | 405 | static size_t syslog_partial; |
7ff9554b KS |
406 | |
407 | /* index and sequence number of the first record stored in the buffer */ | |
408 | static u64 log_first_seq; | |
409 | static u32 log_first_idx; | |
410 | ||
411 | /* index and sequence number of the next record to store in the buffer */ | |
412 | static u64 log_next_seq; | |
413 | static u32 log_next_idx; | |
414 | ||
eab07260 KS |
415 | /* the next printk record to write to the console */ |
416 | static u64 console_seq; | |
417 | static u32 console_idx; | |
f92b070f | 418 | static u64 exclusive_console_stop_seq; |
eab07260 | 419 | |
7ff9554b KS |
420 | /* the next printk record to read after the last 'clear' command */ |
421 | static u64 clear_seq; | |
422 | static u32 clear_idx; | |
423 | ||
70498253 | 424 | #define PREFIX_MAX 32 |
249771b8 | 425 | #define LOG_LINE_MAX (1024 - PREFIX_MAX) |
7f3a781d | 426 | |
3824657c MK |
427 | #define LOG_LEVEL(v) ((v) & 0x07) |
428 | #define LOG_FACILITY(v) ((v) >> 3 & 0xff) | |
429 | ||
7f3a781d | 430 | /* record buffer */ |
62e32ac3 | 431 | #define LOG_ALIGN __alignof__(struct printk_log) |
7f3a781d | 432 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
e6fe3e5b | 433 | #define LOG_BUF_LEN_MAX (u32)(1 << 31) |
f8450fca | 434 | static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); |
7f3a781d KS |
435 | static char *log_buf = __log_buf; |
436 | static u32 log_buf_len = __LOG_BUF_LEN; | |
437 | ||
14c4000a VH |
438 | /* Return log buffer address */ |
439 | char *log_buf_addr_get(void) | |
440 | { | |
441 | return log_buf; | |
442 | } | |
443 | ||
444 | /* Return log buffer size */ | |
445 | u32 log_buf_len_get(void) | |
446 | { | |
447 | return log_buf_len; | |
448 | } | |
449 | ||
7ff9554b | 450 | /* human readable text of the record */ |
62e32ac3 | 451 | static char *log_text(const struct printk_log *msg) |
7ff9554b | 452 | { |
62e32ac3 | 453 | return (char *)msg + sizeof(struct printk_log); |
7ff9554b KS |
454 | } |
455 | ||
456 | /* optional key/value pair dictionary attached to the record */ | |
62e32ac3 | 457 | static char *log_dict(const struct printk_log *msg) |
7ff9554b | 458 | { |
62e32ac3 | 459 | return (char *)msg + sizeof(struct printk_log) + msg->text_len; |
7ff9554b KS |
460 | } |
461 | ||
462 | /* get record by index; idx must point to valid msg */ | |
62e32ac3 | 463 | static struct printk_log *log_from_idx(u32 idx) |
7ff9554b | 464 | { |
62e32ac3 | 465 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); |
7ff9554b KS |
466 | |
467 | /* | |
468 | * A length == 0 record is the end of buffer marker. Wrap around and | |
469 | * read the message at the start of the buffer. | |
470 | */ | |
471 | if (!msg->len) | |
62e32ac3 | 472 | return (struct printk_log *)log_buf; |
7ff9554b KS |
473 | return msg; |
474 | } | |
475 | ||
476 | /* get next record; idx must point to valid msg */ | |
477 | static u32 log_next(u32 idx) | |
478 | { | |
62e32ac3 | 479 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); |
7ff9554b KS |
480 | |
481 | /* length == 0 indicates the end of the buffer; wrap */ | |
482 | /* | |
483 | * A length == 0 record is the end of buffer marker. Wrap around and | |
484 | * read the message at the start of the buffer as *this* one, and | |
485 | * return the one after that. | |
486 | */ | |
487 | if (!msg->len) { | |
62e32ac3 | 488 | msg = (struct printk_log *)log_buf; |
7ff9554b KS |
489 | return msg->len; |
490 | } | |
491 | return idx + msg->len; | |
492 | } | |
493 | ||
f40e4b9f PM |
494 | /* |
495 | * Check whether there is enough free space for the given message. | |
496 | * | |
497 | * The same values of first_idx and next_idx mean that the buffer | |
498 | * is either empty or full. | |
499 | * | |
500 | * If the buffer is empty, we must respect the position of the indexes. | |
501 | * They cannot be reset to the beginning of the buffer. | |
502 | */ | |
503 | static int logbuf_has_space(u32 msg_size, bool empty) | |
0a581694 PM |
504 | { |
505 | u32 free; | |
506 | ||
f40e4b9f | 507 | if (log_next_idx > log_first_idx || empty) |
0a581694 PM |
508 | free = max(log_buf_len - log_next_idx, log_first_idx); |
509 | else | |
510 | free = log_first_idx - log_next_idx; | |
511 | ||
512 | /* | |
513 | * We need space also for an empty header that signalizes wrapping | |
514 | * of the buffer. | |
515 | */ | |
516 | return free >= msg_size + sizeof(struct printk_log); | |
517 | } | |
518 | ||
f40e4b9f | 519 | static int log_make_free_space(u32 msg_size) |
0a581694 | 520 | { |
f468908b ID |
521 | while (log_first_seq < log_next_seq && |
522 | !logbuf_has_space(msg_size, false)) { | |
0b90fec3 | 523 | /* drop old messages until we have enough contiguous space */ |
0a581694 PM |
524 | log_first_idx = log_next(log_first_idx); |
525 | log_first_seq++; | |
526 | } | |
f40e4b9f | 527 | |
f468908b ID |
528 | if (clear_seq < log_first_seq) { |
529 | clear_seq = log_first_seq; | |
530 | clear_idx = log_first_idx; | |
531 | } | |
532 | ||
f40e4b9f | 533 | /* sequence numbers are equal, so the log buffer is empty */ |
f468908b | 534 | if (logbuf_has_space(msg_size, log_first_seq == log_next_seq)) |
f40e4b9f PM |
535 | return 0; |
536 | ||
537 | return -ENOMEM; | |
0a581694 PM |
538 | } |
539 | ||
85c87043 PM |
540 | /* compute the message size including the padding bytes */ |
541 | static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len) | |
542 | { | |
543 | u32 size; | |
544 | ||
545 | size = sizeof(struct printk_log) + text_len + dict_len; | |
546 | *pad_len = (-size) & (LOG_ALIGN - 1); | |
547 | size += *pad_len; | |
548 | ||
549 | return size; | |
550 | } | |
551 | ||
55bd53a4 PM |
552 | /* |
553 | * Define how much of the log buffer we could take at maximum. The value | |
554 | * must be greater than two. Note that only half of the buffer is available | |
555 | * when the index points to the middle. | |
556 | */ | |
557 | #define MAX_LOG_TAKE_PART 4 | |
558 | static const char trunc_msg[] = "<truncated>"; | |
559 | ||
560 | static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len, | |
561 | u16 *dict_len, u32 *pad_len) | |
562 | { | |
563 | /* | |
564 | * The message should not take the whole buffer. Otherwise, it might | |
565 | * get removed too soon. | |
566 | */ | |
567 | u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART; | |
568 | if (*text_len > max_text_len) | |
569 | *text_len = max_text_len; | |
570 | /* enable the warning message */ | |
571 | *trunc_msg_len = strlen(trunc_msg); | |
572 | /* disable the "dict" completely */ | |
573 | *dict_len = 0; | |
574 | /* compute the size again, count also the warning message */ | |
575 | return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len); | |
576 | } | |
577 | ||
7ff9554b | 578 | /* insert record into the buffer, discard old ones, update heads */ |
034633cc PM |
579 | static int log_store(int facility, int level, |
580 | enum log_flags flags, u64 ts_nsec, | |
581 | const char *dict, u16 dict_len, | |
582 | const char *text, u16 text_len) | |
7ff9554b | 583 | { |
62e32ac3 | 584 | struct printk_log *msg; |
7ff9554b | 585 | u32 size, pad_len; |
55bd53a4 | 586 | u16 trunc_msg_len = 0; |
7ff9554b KS |
587 | |
588 | /* number of '\0' padding bytes to next message */ | |
85c87043 | 589 | size = msg_used_size(text_len, dict_len, &pad_len); |
7ff9554b | 590 | |
55bd53a4 PM |
591 | if (log_make_free_space(size)) { |
592 | /* truncate the message if it is too long for empty buffer */ | |
593 | size = truncate_msg(&text_len, &trunc_msg_len, | |
594 | &dict_len, &pad_len); | |
595 | /* survive when the log buffer is too small for trunc_msg */ | |
596 | if (log_make_free_space(size)) | |
034633cc | 597 | return 0; |
55bd53a4 | 598 | } |
7ff9554b | 599 | |
39b25109 | 600 | if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) { |
7ff9554b KS |
601 | /* |
602 | * This message + an additional empty header does not fit | |
603 | * at the end of the buffer. Add an empty header with len == 0 | |
604 | * to signify a wrap around. | |
605 | */ | |
62e32ac3 | 606 | memset(log_buf + log_next_idx, 0, sizeof(struct printk_log)); |
7ff9554b KS |
607 | log_next_idx = 0; |
608 | } | |
609 | ||
610 | /* fill message */ | |
62e32ac3 | 611 | msg = (struct printk_log *)(log_buf + log_next_idx); |
7ff9554b KS |
612 | memcpy(log_text(msg), text, text_len); |
613 | msg->text_len = text_len; | |
55bd53a4 PM |
614 | if (trunc_msg_len) { |
615 | memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len); | |
616 | msg->text_len += trunc_msg_len; | |
617 | } | |
7ff9554b KS |
618 | memcpy(log_dict(msg), dict, dict_len); |
619 | msg->dict_len = dict_len; | |
084681d1 KS |
620 | msg->facility = facility; |
621 | msg->level = level & 7; | |
622 | msg->flags = flags & 0x1f; | |
623 | if (ts_nsec > 0) | |
624 | msg->ts_nsec = ts_nsec; | |
625 | else | |
626 | msg->ts_nsec = local_clock(); | |
7ff9554b | 627 | memset(log_dict(msg) + dict_len, 0, pad_len); |
fce6e033 | 628 | msg->len = size; |
7ff9554b KS |
629 | |
630 | /* insert message */ | |
631 | log_next_idx += msg->len; | |
632 | log_next_seq++; | |
034633cc PM |
633 | |
634 | return msg->text_len; | |
7ff9554b | 635 | } |
d59745ce | 636 | |
e99aa461 | 637 | int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); |
637241a9 KC |
638 | |
639 | static int syslog_action_restricted(int type) | |
640 | { | |
641 | if (dmesg_restrict) | |
642 | return 1; | |
643 | /* | |
644 | * Unless restricted, we allow "read all" and "get buffer size" | |
645 | * for everybody. | |
646 | */ | |
647 | return type != SYSLOG_ACTION_READ_ALL && | |
648 | type != SYSLOG_ACTION_SIZE_BUFFER; | |
649 | } | |
650 | ||
c71b02e4 | 651 | static int check_syslog_permissions(int type, int source) |
637241a9 KC |
652 | { |
653 | /* | |
654 | * If this is from /proc/kmsg and we've already opened it, then we've | |
655 | * already done the capabilities checks at open time. | |
656 | */ | |
3ea4331c | 657 | if (source == SYSLOG_FROM_PROC && type != SYSLOG_ACTION_OPEN) |
d194e5d6 | 658 | goto ok; |
637241a9 KC |
659 | |
660 | if (syslog_action_restricted(type)) { | |
661 | if (capable(CAP_SYSLOG)) | |
d194e5d6 | 662 | goto ok; |
637241a9 KC |
663 | /* |
664 | * For historical reasons, accept CAP_SYS_ADMIN too, with | |
665 | * a warning. | |
666 | */ | |
667 | if (capable(CAP_SYS_ADMIN)) { | |
668 | pr_warn_once("%s (%d): Attempt to access syslog with " | |
669 | "CAP_SYS_ADMIN but no CAP_SYSLOG " | |
670 | "(deprecated).\n", | |
671 | current->comm, task_pid_nr(current)); | |
d194e5d6 | 672 | goto ok; |
637241a9 KC |
673 | } |
674 | return -EPERM; | |
675 | } | |
d194e5d6 | 676 | ok: |
637241a9 KC |
677 | return security_syslog(type); |
678 | } | |
679 | ||
d43ff430 TH |
680 | static void append_char(char **pp, char *e, char c) |
681 | { | |
682 | if (*pp < e) | |
683 | *(*pp)++ = c; | |
684 | } | |
637241a9 | 685 | |
0a295e67 | 686 | static ssize_t msg_print_ext_header(char *buf, size_t size, |
5aa068ea | 687 | struct printk_log *msg, u64 seq) |
0a295e67 TH |
688 | { |
689 | u64 ts_usec = msg->ts_nsec; | |
0a295e67 TH |
690 | |
691 | do_div(ts_usec, 1000); | |
692 | ||
0a295e67 | 693 | return scnprintf(buf, size, "%u,%llu,%llu,%c;", |
5aa068ea LT |
694 | (msg->facility << 3) | msg->level, seq, ts_usec, |
695 | msg->flags & LOG_CONT ? 'c' : '-'); | |
0a295e67 TH |
696 | } |
697 | ||
698 | static ssize_t msg_print_ext_body(char *buf, size_t size, | |
699 | char *dict, size_t dict_len, | |
700 | char *text, size_t text_len) | |
701 | { | |
702 | char *p = buf, *e = buf + size; | |
703 | size_t i; | |
704 | ||
705 | /* escape non-printable characters */ | |
706 | for (i = 0; i < text_len; i++) { | |
707 | unsigned char c = text[i]; | |
708 | ||
709 | if (c < ' ' || c >= 127 || c == '\\') | |
710 | p += scnprintf(p, e - p, "\\x%02x", c); | |
711 | else | |
712 | append_char(&p, e, c); | |
713 | } | |
714 | append_char(&p, e, '\n'); | |
715 | ||
716 | if (dict_len) { | |
717 | bool line = true; | |
718 | ||
719 | for (i = 0; i < dict_len; i++) { | |
720 | unsigned char c = dict[i]; | |
721 | ||
722 | if (line) { | |
723 | append_char(&p, e, ' '); | |
724 | line = false; | |
725 | } | |
726 | ||
727 | if (c == '\0') { | |
728 | append_char(&p, e, '\n'); | |
729 | line = true; | |
730 | continue; | |
731 | } | |
732 | ||
733 | if (c < ' ' || c >= 127 || c == '\\') { | |
734 | p += scnprintf(p, e - p, "\\x%02x", c); | |
735 | continue; | |
736 | } | |
737 | ||
738 | append_char(&p, e, c); | |
739 | } | |
740 | append_char(&p, e, '\n'); | |
741 | } | |
742 | ||
743 | return p - buf; | |
744 | } | |
745 | ||
e11fea92 KS |
746 | /* /dev/kmsg - userspace message inject/listen interface */ |
747 | struct devkmsg_user { | |
748 | u64 seq; | |
749 | u32 idx; | |
750afe7b | 750 | struct ratelimit_state rs; |
e11fea92 | 751 | struct mutex lock; |
d43ff430 | 752 | char buf[CONSOLE_EXT_LOG_MAX]; |
e11fea92 KS |
753 | }; |
754 | ||
849f3127 | 755 | static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from) |
e11fea92 KS |
756 | { |
757 | char *buf, *line; | |
e11fea92 KS |
758 | int level = default_message_loglevel; |
759 | int facility = 1; /* LOG_USER */ | |
750afe7b BP |
760 | struct file *file = iocb->ki_filp; |
761 | struct devkmsg_user *user = file->private_data; | |
66ee59af | 762 | size_t len = iov_iter_count(from); |
e11fea92 KS |
763 | ssize_t ret = len; |
764 | ||
750afe7b | 765 | if (!user || len > LOG_LINE_MAX) |
e11fea92 | 766 | return -EINVAL; |
750afe7b BP |
767 | |
768 | /* Ignore when user logging is disabled. */ | |
769 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) | |
770 | return len; | |
771 | ||
772 | /* Ratelimit when not explicitly enabled. */ | |
773 | if (!(devkmsg_log & DEVKMSG_LOG_MASK_ON)) { | |
774 | if (!___ratelimit(&user->rs, current->comm)) | |
775 | return ret; | |
776 | } | |
777 | ||
e11fea92 KS |
778 | buf = kmalloc(len+1, GFP_KERNEL); |
779 | if (buf == NULL) | |
780 | return -ENOMEM; | |
781 | ||
849f3127 | 782 | buf[len] = '\0'; |
cbbd26b8 | 783 | if (!copy_from_iter_full(buf, len, from)) { |
849f3127 AV |
784 | kfree(buf); |
785 | return -EFAULT; | |
e11fea92 KS |
786 | } |
787 | ||
788 | /* | |
789 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace | |
790 | * the decimal value represents 32bit, the lower 3 bit are the log | |
791 | * level, the rest are the log facility. | |
792 | * | |
793 | * If no prefix or no userspace facility is specified, we | |
794 | * enforce LOG_USER, to be able to reliably distinguish | |
795 | * kernel-generated messages from userspace-injected ones. | |
796 | */ | |
797 | line = buf; | |
798 | if (line[0] == '<') { | |
799 | char *endp = NULL; | |
3824657c | 800 | unsigned int u; |
e11fea92 | 801 | |
3824657c | 802 | u = simple_strtoul(line + 1, &endp, 10); |
e11fea92 | 803 | if (endp && endp[0] == '>') { |
3824657c MK |
804 | level = LOG_LEVEL(u); |
805 | if (LOG_FACILITY(u) != 0) | |
806 | facility = LOG_FACILITY(u); | |
e11fea92 KS |
807 | endp++; |
808 | len -= endp - line; | |
809 | line = endp; | |
810 | } | |
811 | } | |
e11fea92 KS |
812 | |
813 | printk_emit(facility, level, NULL, 0, "%s", line); | |
e11fea92 KS |
814 | kfree(buf); |
815 | return ret; | |
816 | } | |
817 | ||
818 | static ssize_t devkmsg_read(struct file *file, char __user *buf, | |
819 | size_t count, loff_t *ppos) | |
820 | { | |
821 | struct devkmsg_user *user = file->private_data; | |
62e32ac3 | 822 | struct printk_log *msg; |
e11fea92 KS |
823 | size_t len; |
824 | ssize_t ret; | |
825 | ||
826 | if (!user) | |
827 | return -EBADF; | |
828 | ||
4a77a5a0 YL |
829 | ret = mutex_lock_interruptible(&user->lock); |
830 | if (ret) | |
831 | return ret; | |
de6fcbdb SS |
832 | |
833 | logbuf_lock_irq(); | |
e11fea92 KS |
834 | while (user->seq == log_next_seq) { |
835 | if (file->f_flags & O_NONBLOCK) { | |
836 | ret = -EAGAIN; | |
de6fcbdb | 837 | logbuf_unlock_irq(); |
e11fea92 KS |
838 | goto out; |
839 | } | |
840 | ||
de6fcbdb | 841 | logbuf_unlock_irq(); |
e11fea92 KS |
842 | ret = wait_event_interruptible(log_wait, |
843 | user->seq != log_next_seq); | |
844 | if (ret) | |
845 | goto out; | |
de6fcbdb | 846 | logbuf_lock_irq(); |
e11fea92 KS |
847 | } |
848 | ||
849 | if (user->seq < log_first_seq) { | |
850 | /* our last seen message is gone, return error and reset */ | |
851 | user->idx = log_first_idx; | |
852 | user->seq = log_first_seq; | |
853 | ret = -EPIPE; | |
de6fcbdb | 854 | logbuf_unlock_irq(); |
e11fea92 KS |
855 | goto out; |
856 | } | |
857 | ||
858 | msg = log_from_idx(user->idx); | |
0a295e67 | 859 | len = msg_print_ext_header(user->buf, sizeof(user->buf), |
5aa068ea | 860 | msg, user->seq); |
0a295e67 TH |
861 | len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len, |
862 | log_dict(msg), msg->dict_len, | |
863 | log_text(msg), msg->text_len); | |
d39f3d77 | 864 | |
e11fea92 KS |
865 | user->idx = log_next(user->idx); |
866 | user->seq++; | |
de6fcbdb | 867 | logbuf_unlock_irq(); |
e11fea92 KS |
868 | |
869 | if (len > count) { | |
870 | ret = -EINVAL; | |
871 | goto out; | |
872 | } | |
873 | ||
874 | if (copy_to_user(buf, user->buf, len)) { | |
875 | ret = -EFAULT; | |
876 | goto out; | |
877 | } | |
878 | ret = len; | |
879 | out: | |
880 | mutex_unlock(&user->lock); | |
881 | return ret; | |
882 | } | |
883 | ||
884 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) | |
885 | { | |
886 | struct devkmsg_user *user = file->private_data; | |
887 | loff_t ret = 0; | |
888 | ||
889 | if (!user) | |
890 | return -EBADF; | |
891 | if (offset) | |
892 | return -ESPIPE; | |
893 | ||
de6fcbdb | 894 | logbuf_lock_irq(); |
e11fea92 KS |
895 | switch (whence) { |
896 | case SEEK_SET: | |
897 | /* the first record */ | |
898 | user->idx = log_first_idx; | |
899 | user->seq = log_first_seq; | |
900 | break; | |
901 | case SEEK_DATA: | |
902 | /* | |
903 | * The first record after the last SYSLOG_ACTION_CLEAR, | |
904 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself | |
905 | * changes no global state, and does not clear anything. | |
906 | */ | |
907 | user->idx = clear_idx; | |
908 | user->seq = clear_seq; | |
909 | break; | |
910 | case SEEK_END: | |
911 | /* after the last record */ | |
912 | user->idx = log_next_idx; | |
913 | user->seq = log_next_seq; | |
914 | break; | |
915 | default: | |
916 | ret = -EINVAL; | |
917 | } | |
de6fcbdb | 918 | logbuf_unlock_irq(); |
e11fea92 KS |
919 | return ret; |
920 | } | |
921 | ||
9dd95748 | 922 | static __poll_t devkmsg_poll(struct file *file, poll_table *wait) |
e11fea92 KS |
923 | { |
924 | struct devkmsg_user *user = file->private_data; | |
9dd95748 | 925 | __poll_t ret = 0; |
e11fea92 KS |
926 | |
927 | if (!user) | |
a9a08845 | 928 | return EPOLLERR|EPOLLNVAL; |
e11fea92 KS |
929 | |
930 | poll_wait(file, &log_wait, wait); | |
931 | ||
de6fcbdb | 932 | logbuf_lock_irq(); |
e11fea92 KS |
933 | if (user->seq < log_next_seq) { |
934 | /* return error when data has vanished underneath us */ | |
935 | if (user->seq < log_first_seq) | |
a9a08845 | 936 | ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI; |
0a285317 | 937 | else |
a9a08845 | 938 | ret = EPOLLIN|EPOLLRDNORM; |
e11fea92 | 939 | } |
de6fcbdb | 940 | logbuf_unlock_irq(); |
e11fea92 KS |
941 | |
942 | return ret; | |
943 | } | |
944 | ||
945 | static int devkmsg_open(struct inode *inode, struct file *file) | |
946 | { | |
947 | struct devkmsg_user *user; | |
948 | int err; | |
949 | ||
750afe7b BP |
950 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) |
951 | return -EPERM; | |
e11fea92 | 952 | |
750afe7b BP |
953 | /* write-only does not need any file context */ |
954 | if ((file->f_flags & O_ACCMODE) != O_WRONLY) { | |
955 | err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, | |
956 | SYSLOG_FROM_READER); | |
957 | if (err) | |
958 | return err; | |
959 | } | |
e11fea92 KS |
960 | |
961 | user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); | |
962 | if (!user) | |
963 | return -ENOMEM; | |
964 | ||
750afe7b BP |
965 | ratelimit_default_init(&user->rs); |
966 | ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE); | |
967 | ||
e11fea92 KS |
968 | mutex_init(&user->lock); |
969 | ||
de6fcbdb | 970 | logbuf_lock_irq(); |
e11fea92 KS |
971 | user->idx = log_first_idx; |
972 | user->seq = log_first_seq; | |
de6fcbdb | 973 | logbuf_unlock_irq(); |
e11fea92 KS |
974 | |
975 | file->private_data = user; | |
976 | return 0; | |
977 | } | |
978 | ||
979 | static int devkmsg_release(struct inode *inode, struct file *file) | |
980 | { | |
981 | struct devkmsg_user *user = file->private_data; | |
982 | ||
983 | if (!user) | |
984 | return 0; | |
985 | ||
750afe7b BP |
986 | ratelimit_state_exit(&user->rs); |
987 | ||
e11fea92 KS |
988 | mutex_destroy(&user->lock); |
989 | kfree(user); | |
990 | return 0; | |
991 | } | |
992 | ||
993 | const struct file_operations kmsg_fops = { | |
994 | .open = devkmsg_open, | |
995 | .read = devkmsg_read, | |
849f3127 | 996 | .write_iter = devkmsg_write, |
e11fea92 KS |
997 | .llseek = devkmsg_llseek, |
998 | .poll = devkmsg_poll, | |
999 | .release = devkmsg_release, | |
1000 | }; | |
1001 | ||
692f66f2 | 1002 | #ifdef CONFIG_CRASH_CORE |
04d491ab | 1003 | /* |
4c1ace64 | 1004 | * This appends the listed symbols to /proc/vmcore |
04d491ab | 1005 | * |
4c1ace64 | 1006 | * /proc/vmcore is used by various utilities, like crash and makedumpfile to |
04d491ab NH |
1007 | * obtain access to symbols that are otherwise very difficult to locate. These |
1008 | * symbols are specifically used so that utilities can access and extract the | |
1009 | * dmesg log from a vmcore file after a crash. | |
1010 | */ | |
692f66f2 | 1011 | void log_buf_vmcoreinfo_setup(void) |
04d491ab NH |
1012 | { |
1013 | VMCOREINFO_SYMBOL(log_buf); | |
04d491ab | 1014 | VMCOREINFO_SYMBOL(log_buf_len); |
7ff9554b | 1015 | VMCOREINFO_SYMBOL(log_first_idx); |
f468908b | 1016 | VMCOREINFO_SYMBOL(clear_idx); |
7ff9554b | 1017 | VMCOREINFO_SYMBOL(log_next_idx); |
6791457a | 1018 | /* |
62e32ac3 | 1019 | * Export struct printk_log size and field offsets. User space tools can |
6791457a VG |
1020 | * parse it and detect any changes to structure down the line. |
1021 | */ | |
62e32ac3 JP |
1022 | VMCOREINFO_STRUCT_SIZE(printk_log); |
1023 | VMCOREINFO_OFFSET(printk_log, ts_nsec); | |
1024 | VMCOREINFO_OFFSET(printk_log, len); | |
1025 | VMCOREINFO_OFFSET(printk_log, text_len); | |
1026 | VMCOREINFO_OFFSET(printk_log, dict_len); | |
04d491ab NH |
1027 | } |
1028 | #endif | |
1029 | ||
162a7e75 MT |
1030 | /* requested log_buf_len from kernel cmdline */ |
1031 | static unsigned long __initdata new_log_buf_len; | |
1032 | ||
c0a318a3 | 1033 | /* we practice scaling the ring buffer by powers of 2 */ |
e6fe3e5b | 1034 | static void __init log_buf_len_update(u64 size) |
1da177e4 | 1035 | { |
e6fe3e5b HZ |
1036 | if (size > (u64)LOG_BUF_LEN_MAX) { |
1037 | size = (u64)LOG_BUF_LEN_MAX; | |
1038 | pr_err("log_buf over 2G is not supported.\n"); | |
1039 | } | |
1040 | ||
1da177e4 LT |
1041 | if (size) |
1042 | size = roundup_pow_of_two(size); | |
162a7e75 | 1043 | if (size > log_buf_len) |
e6fe3e5b | 1044 | new_log_buf_len = (unsigned long)size; |
c0a318a3 LR |
1045 | } |
1046 | ||
1047 | /* save requested log_buf_len since it's too early to process it */ | |
1048 | static int __init log_buf_len_setup(char *str) | |
1049 | { | |
e6fe3e5b | 1050 | u64 size; |
277fcdb2 HZ |
1051 | |
1052 | if (!str) | |
1053 | return -EINVAL; | |
1054 | ||
1055 | size = memparse(str, &str); | |
c0a318a3 LR |
1056 | |
1057 | log_buf_len_update(size); | |
162a7e75 MT |
1058 | |
1059 | return 0; | |
1da177e4 | 1060 | } |
162a7e75 MT |
1061 | early_param("log_buf_len", log_buf_len_setup); |
1062 | ||
2240a31d GU |
1063 | #ifdef CONFIG_SMP |
1064 | #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) | |
1065 | ||
23b2899f LR |
1066 | static void __init log_buf_add_cpu(void) |
1067 | { | |
1068 | unsigned int cpu_extra; | |
1069 | ||
1070 | /* | |
1071 | * archs should set up cpu_possible_bits properly with | |
1072 | * set_cpu_possible() after setup_arch() but just in | |
1073 | * case lets ensure this is valid. | |
1074 | */ | |
1075 | if (num_possible_cpus() == 1) | |
1076 | return; | |
1077 | ||
1078 | cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; | |
1079 | ||
1080 | /* by default this will only continue through for large > 64 CPUs */ | |
1081 | if (cpu_extra <= __LOG_BUF_LEN / 2) | |
1082 | return; | |
1083 | ||
1084 | pr_info("log_buf_len individual max cpu contribution: %d bytes\n", | |
1085 | __LOG_CPU_MAX_BUF_LEN); | |
1086 | pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", | |
1087 | cpu_extra); | |
1088 | pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); | |
1089 | ||
1090 | log_buf_len_update(cpu_extra + __LOG_BUF_LEN); | |
1091 | } | |
2240a31d GU |
1092 | #else /* !CONFIG_SMP */ |
1093 | static inline void log_buf_add_cpu(void) {} | |
1094 | #endif /* CONFIG_SMP */ | |
23b2899f | 1095 | |
162a7e75 MT |
1096 | void __init setup_log_buf(int early) |
1097 | { | |
1098 | unsigned long flags; | |
162a7e75 | 1099 | char *new_log_buf; |
d2130e82 | 1100 | unsigned int free; |
162a7e75 | 1101 | |
23b2899f LR |
1102 | if (log_buf != __log_buf) |
1103 | return; | |
1104 | ||
1105 | if (!early && !new_log_buf_len) | |
1106 | log_buf_add_cpu(); | |
1107 | ||
162a7e75 MT |
1108 | if (!new_log_buf_len) |
1109 | return; | |
1da177e4 | 1110 | |
162a7e75 | 1111 | if (early) { |
9da791df | 1112 | new_log_buf = |
eb31d559 | 1113 | memblock_alloc(new_log_buf_len, LOG_ALIGN); |
162a7e75 | 1114 | } else { |
eb31d559 | 1115 | new_log_buf = memblock_alloc_nopanic(new_log_buf_len, |
70300177 | 1116 | LOG_ALIGN); |
162a7e75 MT |
1117 | } |
1118 | ||
1119 | if (unlikely(!new_log_buf)) { | |
e6fe3e5b | 1120 | pr_err("log_buf_len: %lu bytes not available\n", |
162a7e75 MT |
1121 | new_log_buf_len); |
1122 | return; | |
1123 | } | |
1124 | ||
de6fcbdb | 1125 | logbuf_lock_irqsave(flags); |
162a7e75 MT |
1126 | log_buf_len = new_log_buf_len; |
1127 | log_buf = new_log_buf; | |
1128 | new_log_buf_len = 0; | |
7ff9554b KS |
1129 | free = __LOG_BUF_LEN - log_next_idx; |
1130 | memcpy(log_buf, __log_buf, __LOG_BUF_LEN); | |
de6fcbdb | 1131 | logbuf_unlock_irqrestore(flags); |
162a7e75 | 1132 | |
e6fe3e5b HZ |
1133 | pr_info("log_buf_len: %u bytes\n", log_buf_len); |
1134 | pr_info("early log buf free: %u(%u%%)\n", | |
162a7e75 MT |
1135 | free, (free * 100) / __LOG_BUF_LEN); |
1136 | } | |
1da177e4 | 1137 | |
2fa72c8f AC |
1138 | static bool __read_mostly ignore_loglevel; |
1139 | ||
1140 | static int __init ignore_loglevel_setup(char *str) | |
1141 | { | |
d25d9fec | 1142 | ignore_loglevel = true; |
27083bac | 1143 | pr_info("debug: ignoring loglevel setting.\n"); |
2fa72c8f AC |
1144 | |
1145 | return 0; | |
1146 | } | |
1147 | ||
1148 | early_param("ignore_loglevel", ignore_loglevel_setup); | |
1149 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); | |
205bd3d2 JP |
1150 | MODULE_PARM_DESC(ignore_loglevel, |
1151 | "ignore loglevel setting (prints all kernel messages to the console)"); | |
2fa72c8f | 1152 | |
cf775444 SS |
1153 | static bool suppress_message_printing(int level) |
1154 | { | |
1155 | return (level >= console_loglevel && !ignore_loglevel); | |
1156 | } | |
1157 | ||
bfe8df3d RD |
1158 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
1159 | ||
674dff65 | 1160 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 1161 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
1162 | |
1163 | static int __init boot_delay_setup(char *str) | |
1164 | { | |
1165 | unsigned long lpj; | |
bfe8df3d RD |
1166 | |
1167 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
1168 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
1169 | ||
1170 | get_option(&str, &boot_delay); | |
1171 | if (boot_delay > 10 * 1000) | |
1172 | boot_delay = 0; | |
1173 | ||
3a3b6ed2 DY |
1174 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
1175 | "HZ: %d, loops_per_msec: %llu\n", | |
1176 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
29e9d225 | 1177 | return 0; |
bfe8df3d | 1178 | } |
29e9d225 | 1179 | early_param("boot_delay", boot_delay_setup); |
bfe8df3d | 1180 | |
2fa72c8f | 1181 | static void boot_delay_msec(int level) |
bfe8df3d RD |
1182 | { |
1183 | unsigned long long k; | |
1184 | unsigned long timeout; | |
1185 | ||
ff48cd26 | 1186 | if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING) |
cf775444 | 1187 | || suppress_message_printing(level)) { |
bfe8df3d | 1188 | return; |
2fa72c8f | 1189 | } |
bfe8df3d | 1190 | |
3a3b6ed2 | 1191 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
1192 | |
1193 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
1194 | while (k) { | |
1195 | k--; | |
1196 | cpu_relax(); | |
1197 | /* | |
1198 | * use (volatile) jiffies to prevent | |
1199 | * compiler reduction; loop termination via jiffies | |
1200 | * is secondary and may or may not happen. | |
1201 | */ | |
1202 | if (time_after(jiffies, timeout)) | |
1203 | break; | |
1204 | touch_nmi_watchdog(); | |
1205 | } | |
1206 | } | |
1207 | #else | |
2fa72c8f | 1208 | static inline void boot_delay_msec(int level) |
bfe8df3d RD |
1209 | { |
1210 | } | |
1211 | #endif | |
1212 | ||
e99aa461 | 1213 | static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); |
7ff9554b KS |
1214 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1215 | ||
084681d1 KS |
1216 | static size_t print_time(u64 ts, char *buf) |
1217 | { | |
1218 | unsigned long rem_nsec; | |
1219 | ||
1220 | if (!printk_time) | |
1221 | return 0; | |
1222 | ||
35dac27c RD |
1223 | rem_nsec = do_div(ts, 1000000000); |
1224 | ||
084681d1 | 1225 | if (!buf) |
35dac27c | 1226 | return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts); |
084681d1 | 1227 | |
084681d1 KS |
1228 | return sprintf(buf, "[%5lu.%06lu] ", |
1229 | (unsigned long)ts, rem_nsec / 1000); | |
1230 | } | |
1231 | ||
62e32ac3 | 1232 | static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf) |
649e6ee3 | 1233 | { |
3ce9a7c0 | 1234 | size_t len = 0; |
43a73a50 | 1235 | unsigned int prefix = (msg->facility << 3) | msg->level; |
649e6ee3 | 1236 | |
3ce9a7c0 KS |
1237 | if (syslog) { |
1238 | if (buf) { | |
43a73a50 | 1239 | len += sprintf(buf, "<%u>", prefix); |
3ce9a7c0 KS |
1240 | } else { |
1241 | len += 3; | |
43a73a50 KS |
1242 | if (prefix > 999) |
1243 | len += 3; | |
1244 | else if (prefix > 99) | |
1245 | len += 2; | |
1246 | else if (prefix > 9) | |
3ce9a7c0 KS |
1247 | len++; |
1248 | } | |
1249 | } | |
649e6ee3 | 1250 | |
084681d1 | 1251 | len += print_time(msg->ts_nsec, buf ? buf + len : NULL); |
3ce9a7c0 | 1252 | return len; |
649e6ee3 KS |
1253 | } |
1254 | ||
5aa068ea | 1255 | static size_t msg_print_text(const struct printk_log *msg, bool syslog, char *buf, size_t size) |
7ff9554b | 1256 | { |
3ce9a7c0 KS |
1257 | const char *text = log_text(msg); |
1258 | size_t text_size = msg->text_len; | |
1259 | size_t len = 0; | |
1260 | ||
1261 | do { | |
1262 | const char *next = memchr(text, '\n', text_size); | |
1263 | size_t text_len; | |
1264 | ||
1265 | if (next) { | |
1266 | text_len = next - text; | |
1267 | next++; | |
1268 | text_size -= next - text; | |
1269 | } else { | |
1270 | text_len = text_size; | |
1271 | } | |
7ff9554b | 1272 | |
3ce9a7c0 KS |
1273 | if (buf) { |
1274 | if (print_prefix(msg, syslog, NULL) + | |
70498253 | 1275 | text_len + 1 >= size - len) |
3ce9a7c0 | 1276 | break; |
7ff9554b | 1277 | |
5aa068ea | 1278 | len += print_prefix(msg, syslog, buf + len); |
3ce9a7c0 KS |
1279 | memcpy(buf + len, text, text_len); |
1280 | len += text_len; | |
5aa068ea | 1281 | buf[len++] = '\n'; |
3ce9a7c0 KS |
1282 | } else { |
1283 | /* SYSLOG_ACTION_* buffer size only calculation */ | |
5aa068ea | 1284 | len += print_prefix(msg, syslog, NULL); |
5becfb1d | 1285 | len += text_len; |
5aa068ea | 1286 | len++; |
3ce9a7c0 | 1287 | } |
7ff9554b | 1288 | |
3ce9a7c0 KS |
1289 | text = next; |
1290 | } while (text); | |
7ff9554b | 1291 | |
7ff9554b KS |
1292 | return len; |
1293 | } | |
1294 | ||
1295 | static int syslog_print(char __user *buf, int size) | |
1296 | { | |
1297 | char *text; | |
62e32ac3 | 1298 | struct printk_log *msg; |
116e90b2 | 1299 | int len = 0; |
7ff9554b | 1300 | |
70498253 | 1301 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
7ff9554b KS |
1302 | if (!text) |
1303 | return -ENOMEM; | |
1304 | ||
116e90b2 JB |
1305 | while (size > 0) { |
1306 | size_t n; | |
eb02dac9 | 1307 | size_t skip; |
116e90b2 | 1308 | |
de6fcbdb | 1309 | logbuf_lock_irq(); |
116e90b2 JB |
1310 | if (syslog_seq < log_first_seq) { |
1311 | /* messages are gone, move to first one */ | |
1312 | syslog_seq = log_first_seq; | |
1313 | syslog_idx = log_first_idx; | |
eb02dac9 | 1314 | syslog_partial = 0; |
116e90b2 JB |
1315 | } |
1316 | if (syslog_seq == log_next_seq) { | |
de6fcbdb | 1317 | logbuf_unlock_irq(); |
116e90b2 JB |
1318 | break; |
1319 | } | |
eb02dac9 KS |
1320 | |
1321 | skip = syslog_partial; | |
116e90b2 | 1322 | msg = log_from_idx(syslog_idx); |
5aa068ea | 1323 | n = msg_print_text(msg, true, text, LOG_LINE_MAX + PREFIX_MAX); |
eb02dac9 KS |
1324 | if (n - syslog_partial <= size) { |
1325 | /* message fits into buffer, move forward */ | |
116e90b2 JB |
1326 | syslog_idx = log_next(syslog_idx); |
1327 | syslog_seq++; | |
eb02dac9 KS |
1328 | n -= syslog_partial; |
1329 | syslog_partial = 0; | |
1330 | } else if (!len){ | |
1331 | /* partial read(), remember position */ | |
1332 | n = size; | |
1333 | syslog_partial += n; | |
116e90b2 JB |
1334 | } else |
1335 | n = 0; | |
de6fcbdb | 1336 | logbuf_unlock_irq(); |
116e90b2 JB |
1337 | |
1338 | if (!n) | |
1339 | break; | |
1340 | ||
eb02dac9 | 1341 | if (copy_to_user(buf, text + skip, n)) { |
116e90b2 JB |
1342 | if (!len) |
1343 | len = -EFAULT; | |
1344 | break; | |
1345 | } | |
eb02dac9 KS |
1346 | |
1347 | len += n; | |
1348 | size -= n; | |
1349 | buf += n; | |
7ff9554b | 1350 | } |
7ff9554b KS |
1351 | |
1352 | kfree(text); | |
1353 | return len; | |
1354 | } | |
1355 | ||
1356 | static int syslog_print_all(char __user *buf, int size, bool clear) | |
1357 | { | |
1358 | char *text; | |
1359 | int len = 0; | |
63842c21 NG |
1360 | u64 next_seq; |
1361 | u64 seq; | |
1362 | u32 idx; | |
1363 | ||
70498253 | 1364 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
7ff9554b KS |
1365 | if (!text) |
1366 | return -ENOMEM; | |
1367 | ||
de6fcbdb | 1368 | logbuf_lock_irq(); |
63842c21 NG |
1369 | /* |
1370 | * Find first record that fits, including all following records, | |
1371 | * into the user-provided buffer for this dump. | |
1372 | */ | |
1373 | seq = clear_seq; | |
1374 | idx = clear_idx; | |
1375 | while (seq < log_next_seq) { | |
1376 | struct printk_log *msg = log_from_idx(idx); | |
1377 | ||
1378 | len += msg_print_text(msg, true, NULL, 0); | |
1379 | idx = log_next(idx); | |
1380 | seq++; | |
1381 | } | |
e2ae715d | 1382 | |
63842c21 NG |
1383 | /* move first record forward until length fits into the buffer */ |
1384 | seq = clear_seq; | |
1385 | idx = clear_idx; | |
1386 | while (len > size && seq < log_next_seq) { | |
1387 | struct printk_log *msg = log_from_idx(idx); | |
3ce9a7c0 | 1388 | |
63842c21 NG |
1389 | len -= msg_print_text(msg, true, NULL, 0); |
1390 | idx = log_next(idx); | |
1391 | seq++; | |
1392 | } | |
7ff9554b | 1393 | |
63842c21 NG |
1394 | /* last message fitting into this dump */ |
1395 | next_seq = log_next_seq; | |
7ff9554b | 1396 | |
63842c21 NG |
1397 | len = 0; |
1398 | while (len >= 0 && seq < next_seq) { | |
1399 | struct printk_log *msg = log_from_idx(idx); | |
1400 | int textlen; | |
7ff9554b | 1401 | |
63842c21 NG |
1402 | textlen = msg_print_text(msg, true, text, |
1403 | LOG_LINE_MAX + PREFIX_MAX); | |
1404 | if (textlen < 0) { | |
1405 | len = textlen; | |
1406 | break; | |
1407 | } | |
1408 | idx = log_next(idx); | |
1409 | seq++; | |
7ff9554b | 1410 | |
63842c21 NG |
1411 | logbuf_unlock_irq(); |
1412 | if (copy_to_user(buf + len, text, textlen)) | |
1413 | len = -EFAULT; | |
1414 | else | |
1415 | len += textlen; | |
1416 | logbuf_lock_irq(); | |
7ff9554b | 1417 | |
63842c21 NG |
1418 | if (seq < log_first_seq) { |
1419 | /* messages are gone, move to next one */ | |
1420 | seq = log_first_seq; | |
1421 | idx = log_first_idx; | |
7ff9554b KS |
1422 | } |
1423 | } | |
1424 | ||
1425 | if (clear) { | |
1426 | clear_seq = log_next_seq; | |
1427 | clear_idx = log_next_idx; | |
1428 | } | |
de6fcbdb | 1429 | logbuf_unlock_irq(); |
7ff9554b KS |
1430 | |
1431 | kfree(text); | |
1432 | return len; | |
1433 | } | |
1434 | ||
8599dc7d PM |
1435 | static void syslog_clear(void) |
1436 | { | |
1437 | logbuf_lock_irq(); | |
1438 | clear_seq = log_next_seq; | |
1439 | clear_idx = log_next_idx; | |
1440 | logbuf_unlock_irq(); | |
1441 | } | |
1442 | ||
3ea4331c | 1443 | int do_syslog(int type, char __user *buf, int len, int source) |
1da177e4 | 1444 | { |
7ff9554b | 1445 | bool clear = false; |
a39d4a85 | 1446 | static int saved_console_loglevel = LOGLEVEL_DEFAULT; |
ee24aebf | 1447 | int error; |
1da177e4 | 1448 | |
3ea4331c | 1449 | error = check_syslog_permissions(type, source); |
ee24aebf | 1450 | if (error) |
077a1cc0 | 1451 | return error; |
12b3052c | 1452 | |
1da177e4 | 1453 | switch (type) { |
d78ca3cd | 1454 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 1455 | break; |
d78ca3cd | 1456 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 1457 | break; |
d78ca3cd | 1458 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 | 1459 | if (!buf || len < 0) |
077a1cc0 | 1460 | return -EINVAL; |
1da177e4 | 1461 | if (!len) |
077a1cc0 NA |
1462 | return 0; |
1463 | if (!access_ok(VERIFY_WRITE, buf, len)) | |
1464 | return -EFAULT; | |
40dc5651 | 1465 | error = wait_event_interruptible(log_wait, |
7ff9554b | 1466 | syslog_seq != log_next_seq); |
cb424ffe | 1467 | if (error) |
077a1cc0 | 1468 | return error; |
7ff9554b | 1469 | error = syslog_print(buf, len); |
1da177e4 | 1470 | break; |
d78ca3cd KC |
1471 | /* Read/clear last kernel messages */ |
1472 | case SYSLOG_ACTION_READ_CLEAR: | |
7ff9554b | 1473 | clear = true; |
1da177e4 | 1474 | /* FALL THRU */ |
d78ca3cd KC |
1475 | /* Read last kernel messages */ |
1476 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 | 1477 | if (!buf || len < 0) |
077a1cc0 | 1478 | return -EINVAL; |
1da177e4 | 1479 | if (!len) |
077a1cc0 NA |
1480 | return 0; |
1481 | if (!access_ok(VERIFY_WRITE, buf, len)) | |
1482 | return -EFAULT; | |
7ff9554b | 1483 | error = syslog_print_all(buf, len, clear); |
1da177e4 | 1484 | break; |
d78ca3cd KC |
1485 | /* Clear ring buffer */ |
1486 | case SYSLOG_ACTION_CLEAR: | |
8599dc7d | 1487 | syslog_clear(); |
4661e356 | 1488 | break; |
d78ca3cd KC |
1489 | /* Disable logging to console */ |
1490 | case SYSLOG_ACTION_CONSOLE_OFF: | |
a39d4a85 | 1491 | if (saved_console_loglevel == LOGLEVEL_DEFAULT) |
1aaad49e | 1492 | saved_console_loglevel = console_loglevel; |
1da177e4 LT |
1493 | console_loglevel = minimum_console_loglevel; |
1494 | break; | |
d78ca3cd KC |
1495 | /* Enable logging to console */ |
1496 | case SYSLOG_ACTION_CONSOLE_ON: | |
a39d4a85 | 1497 | if (saved_console_loglevel != LOGLEVEL_DEFAULT) { |
1aaad49e | 1498 | console_loglevel = saved_console_loglevel; |
a39d4a85 | 1499 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1aaad49e | 1500 | } |
1da177e4 | 1501 | break; |
d78ca3cd KC |
1502 | /* Set level of messages printed to console */ |
1503 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 | 1504 | if (len < 1 || len > 8) |
077a1cc0 | 1505 | return -EINVAL; |
1da177e4 LT |
1506 | if (len < minimum_console_loglevel) |
1507 | len = minimum_console_loglevel; | |
1508 | console_loglevel = len; | |
1aaad49e | 1509 | /* Implicitly re-enable logging to console */ |
a39d4a85 | 1510 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1da177e4 | 1511 | break; |
d78ca3cd KC |
1512 | /* Number of chars in the log buffer */ |
1513 | case SYSLOG_ACTION_SIZE_UNREAD: | |
de6fcbdb | 1514 | logbuf_lock_irq(); |
7ff9554b KS |
1515 | if (syslog_seq < log_first_seq) { |
1516 | /* messages are gone, move to first one */ | |
1517 | syslog_seq = log_first_seq; | |
1518 | syslog_idx = log_first_idx; | |
eb02dac9 | 1519 | syslog_partial = 0; |
7ff9554b | 1520 | } |
3ea4331c | 1521 | if (source == SYSLOG_FROM_PROC) { |
7ff9554b KS |
1522 | /* |
1523 | * Short-cut for poll(/"proc/kmsg") which simply checks | |
1524 | * for pending data, not the size; return the count of | |
1525 | * records, not the length. | |
1526 | */ | |
e97e1267 | 1527 | error = log_next_seq - syslog_seq; |
7ff9554b | 1528 | } else { |
5becfb1d KS |
1529 | u64 seq = syslog_seq; |
1530 | u32 idx = syslog_idx; | |
7ff9554b | 1531 | |
7ff9554b | 1532 | while (seq < log_next_seq) { |
62e32ac3 | 1533 | struct printk_log *msg = log_from_idx(idx); |
3ce9a7c0 | 1534 | |
5aa068ea | 1535 | error += msg_print_text(msg, true, NULL, 0); |
7ff9554b KS |
1536 | idx = log_next(idx); |
1537 | seq++; | |
1538 | } | |
eb02dac9 | 1539 | error -= syslog_partial; |
7ff9554b | 1540 | } |
de6fcbdb | 1541 | logbuf_unlock_irq(); |
1da177e4 | 1542 | break; |
d78ca3cd KC |
1543 | /* Size of the log buffer */ |
1544 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
1545 | error = log_buf_len; |
1546 | break; | |
1547 | default: | |
1548 | error = -EINVAL; | |
1549 | break; | |
1550 | } | |
077a1cc0 | 1551 | |
1da177e4 LT |
1552 | return error; |
1553 | } | |
1554 | ||
1e7bfb21 | 1555 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 1556 | { |
637241a9 | 1557 | return do_syslog(type, buf, len, SYSLOG_FROM_READER); |
1da177e4 LT |
1558 | } |
1559 | ||
c162d5b4 PM |
1560 | /* |
1561 | * Special console_lock variants that help to reduce the risk of soft-lockups. | |
1562 | * They allow to pass console_lock to another printk() call using a busy wait. | |
1563 | */ | |
1564 | ||
1565 | #ifdef CONFIG_LOCKDEP | |
1566 | static struct lockdep_map console_owner_dep_map = { | |
1567 | .name = "console_owner" | |
1568 | }; | |
1569 | #endif | |
1570 | ||
1571 | static DEFINE_RAW_SPINLOCK(console_owner_lock); | |
1572 | static struct task_struct *console_owner; | |
1573 | static bool console_waiter; | |
1574 | ||
1575 | /** | |
1576 | * console_lock_spinning_enable - mark beginning of code where another | |
1577 | * thread might safely busy wait | |
1578 | * | |
1579 | * This basically converts console_lock into a spinlock. This marks | |
1580 | * the section where the console_lock owner can not sleep, because | |
1581 | * there may be a waiter spinning (like a spinlock). Also it must be | |
1582 | * ready to hand over the lock at the end of the section. | |
1583 | */ | |
1584 | static void console_lock_spinning_enable(void) | |
1585 | { | |
1586 | raw_spin_lock(&console_owner_lock); | |
1587 | console_owner = current; | |
1588 | raw_spin_unlock(&console_owner_lock); | |
1589 | ||
1590 | /* The waiter may spin on us after setting console_owner */ | |
1591 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
1592 | } | |
1593 | ||
1594 | /** | |
1595 | * console_lock_spinning_disable_and_check - mark end of code where another | |
1596 | * thread was able to busy wait and check if there is a waiter | |
1597 | * | |
1598 | * This is called at the end of the section where spinning is allowed. | |
1599 | * It has two functions. First, it is a signal that it is no longer | |
1600 | * safe to start busy waiting for the lock. Second, it checks if | |
1601 | * there is a busy waiter and passes the lock rights to her. | |
1602 | * | |
1603 | * Important: Callers lose the lock if there was a busy waiter. | |
1604 | * They must not touch items synchronized by console_lock | |
1605 | * in this case. | |
1606 | * | |
1607 | * Return: 1 if the lock rights were passed, 0 otherwise. | |
1608 | */ | |
1609 | static int console_lock_spinning_disable_and_check(void) | |
1610 | { | |
1611 | int waiter; | |
1612 | ||
1613 | raw_spin_lock(&console_owner_lock); | |
1614 | waiter = READ_ONCE(console_waiter); | |
1615 | console_owner = NULL; | |
1616 | raw_spin_unlock(&console_owner_lock); | |
1617 | ||
1618 | if (!waiter) { | |
1619 | spin_release(&console_owner_dep_map, 1, _THIS_IP_); | |
1620 | return 0; | |
1621 | } | |
1622 | ||
1623 | /* The waiter is now free to continue */ | |
1624 | WRITE_ONCE(console_waiter, false); | |
1625 | ||
1626 | spin_release(&console_owner_dep_map, 1, _THIS_IP_); | |
1627 | ||
1628 | /* | |
1629 | * Hand off console_lock to waiter. The waiter will perform | |
1630 | * the up(). After this, the waiter is the console_lock owner. | |
1631 | */ | |
1632 | mutex_release(&console_lock_dep_map, 1, _THIS_IP_); | |
1633 | return 1; | |
1634 | } | |
1635 | ||
1636 | /** | |
1637 | * console_trylock_spinning - try to get console_lock by busy waiting | |
1638 | * | |
1639 | * This allows to busy wait for the console_lock when the current | |
1640 | * owner is running in specially marked sections. It means that | |
1641 | * the current owner is running and cannot reschedule until it | |
1642 | * is ready to lose the lock. | |
1643 | * | |
1644 | * Return: 1 if we got the lock, 0 othrewise | |
1645 | */ | |
1646 | static int console_trylock_spinning(void) | |
1647 | { | |
1648 | struct task_struct *owner = NULL; | |
1649 | bool waiter; | |
1650 | bool spin = false; | |
1651 | unsigned long flags; | |
1652 | ||
1653 | if (console_trylock()) | |
1654 | return 1; | |
1655 | ||
1656 | printk_safe_enter_irqsave(flags); | |
1657 | ||
1658 | raw_spin_lock(&console_owner_lock); | |
1659 | owner = READ_ONCE(console_owner); | |
1660 | waiter = READ_ONCE(console_waiter); | |
1661 | if (!waiter && owner && owner != current) { | |
1662 | WRITE_ONCE(console_waiter, true); | |
1663 | spin = true; | |
1664 | } | |
1665 | raw_spin_unlock(&console_owner_lock); | |
1666 | ||
1667 | /* | |
1668 | * If there is an active printk() writing to the | |
1669 | * consoles, instead of having it write our data too, | |
1670 | * see if we can offload that load from the active | |
1671 | * printer, and do some printing ourselves. | |
1672 | * Go into a spin only if there isn't already a waiter | |
1673 | * spinning, and there is an active printer, and | |
1674 | * that active printer isn't us (recursive printk?). | |
1675 | */ | |
1676 | if (!spin) { | |
1677 | printk_safe_exit_irqrestore(flags); | |
1678 | return 0; | |
1679 | } | |
1680 | ||
1681 | /* We spin waiting for the owner to release us */ | |
1682 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
1683 | /* Owner will clear console_waiter on hand off */ | |
1684 | while (READ_ONCE(console_waiter)) | |
1685 | cpu_relax(); | |
1686 | spin_release(&console_owner_dep_map, 1, _THIS_IP_); | |
1687 | ||
1688 | printk_safe_exit_irqrestore(flags); | |
1689 | /* | |
1690 | * The owner passed the console lock to us. | |
1691 | * Since we did not spin on console lock, annotate | |
1692 | * this as a trylock. Otherwise lockdep will | |
1693 | * complain. | |
1694 | */ | |
1695 | mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_); | |
1696 | ||
1697 | return 1; | |
1698 | } | |
1699 | ||
1da177e4 LT |
1700 | /* |
1701 | * Call the console drivers, asking them to write out | |
1702 | * log_buf[start] to log_buf[end - 1]. | |
ac751efa | 1703 | * The console_lock must be held. |
1da177e4 | 1704 | */ |
d9c23523 | 1705 | static void call_console_drivers(const char *ext_text, size_t ext_len, |
6fe29354 | 1706 | const char *text, size_t len) |
1da177e4 | 1707 | { |
7ff9554b | 1708 | struct console *con; |
1da177e4 | 1709 | |
fc98c3c8 | 1710 | trace_console_rcuidle(text, len); |
7ff9554b | 1711 | |
7ff9554b KS |
1712 | if (!console_drivers) |
1713 | return; | |
1714 | ||
1715 | for_each_console(con) { | |
1716 | if (exclusive_console && con != exclusive_console) | |
1717 | continue; | |
1718 | if (!(con->flags & CON_ENABLED)) | |
1719 | continue; | |
1720 | if (!con->write) | |
1721 | continue; | |
1722 | if (!cpu_online(smp_processor_id()) && | |
1723 | !(con->flags & CON_ANYTIME)) | |
1724 | continue; | |
6fe29354 TH |
1725 | if (con->flags & CON_EXTENDED) |
1726 | con->write(con, ext_text, ext_len); | |
1727 | else | |
1728 | con->write(con, text, len); | |
7ff9554b | 1729 | } |
1da177e4 LT |
1730 | } |
1731 | ||
af91322e DY |
1732 | int printk_delay_msec __read_mostly; |
1733 | ||
1734 | static inline void printk_delay(void) | |
1735 | { | |
1736 | if (unlikely(printk_delay_msec)) { | |
1737 | int m = printk_delay_msec; | |
1738 | ||
1739 | while (m--) { | |
1740 | mdelay(1); | |
1741 | touch_nmi_watchdog(); | |
1742 | } | |
1743 | } | |
1744 | } | |
1745 | ||
084681d1 KS |
1746 | /* |
1747 | * Continuation lines are buffered, and not committed to the record buffer | |
1748 | * until the line is complete, or a race forces it. The line fragments | |
1749 | * though, are printed immediately to the consoles to ensure everything has | |
1750 | * reached the console in case of a kernel crash. | |
1751 | */ | |
1752 | static struct cont { | |
1753 | char buf[LOG_LINE_MAX]; | |
1754 | size_t len; /* length == 0 means unused buffer */ | |
084681d1 KS |
1755 | struct task_struct *owner; /* task of first print*/ |
1756 | u64 ts_nsec; /* time of first print */ | |
1757 | u8 level; /* log level of first message */ | |
0b90fec3 | 1758 | u8 facility; /* log facility of first message */ |
eab07260 | 1759 | enum log_flags flags; /* prefix, newline flags */ |
084681d1 KS |
1760 | } cont; |
1761 | ||
5e467652 | 1762 | static void cont_flush(void) |
084681d1 | 1763 | { |
084681d1 KS |
1764 | if (cont.len == 0) |
1765 | return; | |
5c2992ee LT |
1766 | |
1767 | log_store(cont.facility, cont.level, cont.flags, cont.ts_nsec, | |
1768 | NULL, 0, cont.buf, cont.len); | |
1769 | cont.len = 0; | |
084681d1 KS |
1770 | } |
1771 | ||
5e467652 | 1772 | static bool cont_add(int facility, int level, enum log_flags flags, const char *text, size_t len) |
084681d1 | 1773 | { |
9627808d SS |
1774 | /* If the line gets too long, split it up in separate records. */ |
1775 | if (cont.len + len > sizeof(cont.buf)) { | |
5e467652 | 1776 | cont_flush(); |
084681d1 KS |
1777 | return false; |
1778 | } | |
1779 | ||
1780 | if (!cont.len) { | |
1781 | cont.facility = facility; | |
1782 | cont.level = level; | |
1783 | cont.owner = current; | |
1784 | cont.ts_nsec = local_clock(); | |
5e467652 | 1785 | cont.flags = flags; |
084681d1 KS |
1786 | } |
1787 | ||
1788 | memcpy(cont.buf + cont.len, text, len); | |
1789 | cont.len += len; | |
eab07260 | 1790 | |
5e467652 LT |
1791 | // The original flags come from the first line, |
1792 | // but later continuations can add a newline. | |
1793 | if (flags & LOG_NEWLINE) { | |
1794 | cont.flags |= LOG_NEWLINE; | |
1795 | cont_flush(); | |
1796 | } | |
1797 | ||
084681d1 KS |
1798 | return true; |
1799 | } | |
1800 | ||
c362c7ff LT |
1801 | static size_t log_output(int facility, int level, enum log_flags lflags, const char *dict, size_t dictlen, char *text, size_t text_len) |
1802 | { | |
c362c7ff | 1803 | /* |
5e467652 LT |
1804 | * If an earlier line was buffered, and we're a continuation |
1805 | * write from the same process, try to add it to the buffer. | |
c362c7ff LT |
1806 | */ |
1807 | if (cont.len) { | |
5e467652 LT |
1808 | if (cont.owner == current && (lflags & LOG_CONT)) { |
1809 | if (cont_add(facility, level, lflags, text, text_len)) | |
1810 | return text_len; | |
1811 | } | |
1812 | /* Otherwise, make sure it's flushed */ | |
1813 | cont_flush(); | |
1814 | } | |
c362c7ff | 1815 | |
8835ca59 LT |
1816 | /* Skip empty continuation lines that couldn't be added - they just flush */ |
1817 | if (!text_len && (lflags & LOG_CONT)) | |
1818 | return 0; | |
1819 | ||
5e467652 LT |
1820 | /* If it doesn't end in a newline, try to buffer the current line */ |
1821 | if (!(lflags & LOG_NEWLINE)) { | |
1822 | if (cont_add(facility, level, lflags, text, text_len)) | |
c362c7ff LT |
1823 | return text_len; |
1824 | } | |
1825 | ||
5e467652 | 1826 | /* Store it in the record log */ |
c362c7ff LT |
1827 | return log_store(facility, level, lflags, 0, dict, dictlen, text, text_len); |
1828 | } | |
1829 | ||
ba552399 PM |
1830 | /* Must be called under logbuf_lock. */ |
1831 | int vprintk_store(int facility, int level, | |
1832 | const char *dict, size_t dictlen, | |
1833 | const char *fmt, va_list args) | |
1da177e4 | 1834 | { |
7ff9554b KS |
1835 | static char textbuf[LOG_LINE_MAX]; |
1836 | char *text = textbuf; | |
aec47caa | 1837 | size_t text_len; |
5becfb1d | 1838 | enum log_flags lflags = 0; |
bfe8df3d | 1839 | |
7ff9554b KS |
1840 | /* |
1841 | * The printf needs to come first; we need the syslog | |
1842 | * prefix which might be passed-in as a parameter. | |
1843 | */ | |
98e35f58 | 1844 | text_len = vscnprintf(text, sizeof(textbuf), fmt, args); |
5fd29d6c | 1845 | |
7ff9554b | 1846 | /* mark and strip a trailing newline */ |
c313af14 KS |
1847 | if (text_len && text[text_len-1] == '\n') { |
1848 | text_len--; | |
5becfb1d | 1849 | lflags |= LOG_NEWLINE; |
7ff9554b | 1850 | } |
9d90c8d9 | 1851 | |
088a52aa JP |
1852 | /* strip kernel syslog prefix and extract log level or control flags */ |
1853 | if (facility == 0) { | |
4bcc595c | 1854 | int kern_level; |
088a52aa | 1855 | |
4bcc595c | 1856 | while ((kern_level = printk_get_level(text)) != 0) { |
088a52aa JP |
1857 | switch (kern_level) { |
1858 | case '0' ... '7': | |
a39d4a85 | 1859 | if (level == LOGLEVEL_DEFAULT) |
088a52aa | 1860 | level = kern_level - '0'; |
a39d4a85 | 1861 | /* fallthrough */ |
088a52aa JP |
1862 | case 'd': /* KERN_DEFAULT */ |
1863 | lflags |= LOG_PREFIX; | |
4bcc595c LT |
1864 | break; |
1865 | case 'c': /* KERN_CONT */ | |
1866 | lflags |= LOG_CONT; | |
088a52aa | 1867 | } |
4bcc595c LT |
1868 | |
1869 | text_len -= 2; | |
1870 | text += 2; | |
5fd29d6c LT |
1871 | } |
1872 | } | |
1873 | ||
a39d4a85 | 1874 | if (level == LOGLEVEL_DEFAULT) |
c313af14 | 1875 | level = default_message_loglevel; |
9d90c8d9 | 1876 | |
5becfb1d KS |
1877 | if (dict) |
1878 | lflags |= LOG_PREFIX|LOG_NEWLINE; | |
ac60ad74 | 1879 | |
ba552399 PM |
1880 | return log_output(facility, level, lflags, |
1881 | dict, dictlen, text, text_len); | |
1882 | } | |
1da177e4 | 1883 | |
ba552399 PM |
1884 | asmlinkage int vprintk_emit(int facility, int level, |
1885 | const char *dict, size_t dictlen, | |
1886 | const char *fmt, va_list args) | |
1887 | { | |
1888 | int printed_len; | |
3ac37a93 | 1889 | bool in_sched = false, pending_output; |
ba552399 | 1890 | unsigned long flags; |
3ac37a93 | 1891 | u64 curr_log_seq; |
ba552399 PM |
1892 | |
1893 | if (level == LOGLEVEL_SCHED) { | |
1894 | level = LOGLEVEL_DEFAULT; | |
1895 | in_sched = true; | |
1896 | } | |
1897 | ||
1898 | boot_delay_msec(level); | |
1899 | printk_delay(); | |
1900 | ||
1901 | /* This stops the holder of console_sem just where we want him */ | |
1902 | logbuf_lock_irqsave(flags); | |
3ac37a93 | 1903 | curr_log_seq = log_next_seq; |
ba552399 | 1904 | printed_len = vprintk_store(facility, level, dict, dictlen, fmt, args); |
3ac37a93 | 1905 | pending_output = (curr_log_seq != log_next_seq); |
de6fcbdb | 1906 | logbuf_unlock_irqrestore(flags); |
939f04be | 1907 | |
458df9fd | 1908 | /* If called from the scheduler, we can not call up(). */ |
3ac37a93 | 1909 | if (!in_sched && pending_output) { |
fd5f7cde SS |
1910 | /* |
1911 | * Disable preemption to avoid being preempted while holding | |
1912 | * console_sem which would prevent anyone from printing to | |
1913 | * console | |
1914 | */ | |
1915 | preempt_disable(); | |
d18bbc21 AM |
1916 | /* |
1917 | * Try to acquire and then immediately release the console | |
1918 | * semaphore. The release will print out buffers and wake up | |
1919 | * /dev/kmsg and syslog() users. | |
1920 | */ | |
c162d5b4 | 1921 | if (console_trylock_spinning()) |
d18bbc21 | 1922 | console_unlock(); |
fd5f7cde | 1923 | preempt_enable(); |
d18bbc21 | 1924 | } |
76a8ad29 | 1925 | |
3ac37a93 SS |
1926 | if (pending_output) |
1927 | wake_up_klogd(); | |
1da177e4 LT |
1928 | return printed_len; |
1929 | } | |
7ff9554b KS |
1930 | EXPORT_SYMBOL(vprintk_emit); |
1931 | ||
1932 | asmlinkage int vprintk(const char *fmt, va_list args) | |
1933 | { | |
bd66a892 | 1934 | return vprintk_func(fmt, args); |
7ff9554b | 1935 | } |
1da177e4 LT |
1936 | EXPORT_SYMBOL(vprintk); |
1937 | ||
7ff9554b KS |
1938 | asmlinkage int printk_emit(int facility, int level, |
1939 | const char *dict, size_t dictlen, | |
1940 | const char *fmt, ...) | |
1941 | { | |
1942 | va_list args; | |
1943 | int r; | |
1944 | ||
1945 | va_start(args, fmt); | |
1946 | r = vprintk_emit(facility, level, dict, dictlen, fmt, args); | |
1947 | va_end(args); | |
1948 | ||
1949 | return r; | |
1950 | } | |
1951 | EXPORT_SYMBOL(printk_emit); | |
1952 | ||
a0cba217 | 1953 | int vprintk_default(const char *fmt, va_list args) |
afdc34a3 SRRH |
1954 | { |
1955 | int r; | |
1956 | ||
1957 | #ifdef CONFIG_KGDB_KDB | |
34aaff40 PM |
1958 | /* Allow to pass printk() to kdb but avoid a recursion. */ |
1959 | if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) { | |
f7d4ca8b | 1960 | r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args); |
afdc34a3 SRRH |
1961 | return r; |
1962 | } | |
1963 | #endif | |
a0cba217 | 1964 | r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); |
afdc34a3 SRRH |
1965 | |
1966 | return r; | |
1967 | } | |
1968 | EXPORT_SYMBOL_GPL(vprintk_default); | |
1969 | ||
7ff9554b KS |
1970 | /** |
1971 | * printk - print a kernel message | |
1972 | * @fmt: format string | |
1973 | * | |
1974 | * This is printk(). It can be called from any context. We want it to work. | |
1975 | * | |
1976 | * We try to grab the console_lock. If we succeed, it's easy - we log the | |
1977 | * output and call the console drivers. If we fail to get the semaphore, we | |
1978 | * place the output into the log buffer and return. The current holder of | |
1979 | * the console_sem will notice the new output in console_unlock(); and will | |
1980 | * send it to the consoles before releasing the lock. | |
1981 | * | |
1982 | * One effect of this deferred printing is that code which calls printk() and | |
1983 | * then changes console_loglevel may break. This is because console_loglevel | |
1984 | * is inspected when the actual printing occurs. | |
1985 | * | |
1986 | * See also: | |
1987 | * printf(3) | |
1988 | * | |
1989 | * See the vsnprintf() documentation for format string extensions over C99. | |
1990 | */ | |
722a9f92 | 1991 | asmlinkage __visible int printk(const char *fmt, ...) |
7ff9554b KS |
1992 | { |
1993 | va_list args; | |
1994 | int r; | |
1995 | ||
7ff9554b | 1996 | va_start(args, fmt); |
a0cba217 | 1997 | r = vprintk_func(fmt, args); |
7ff9554b KS |
1998 | va_end(args); |
1999 | ||
2000 | return r; | |
2001 | } | |
2002 | EXPORT_SYMBOL(printk); | |
7f3a781d | 2003 | |
96efedf1 | 2004 | #else /* CONFIG_PRINTK */ |
d59745ce | 2005 | |
70498253 KS |
2006 | #define LOG_LINE_MAX 0 |
2007 | #define PREFIX_MAX 0 | |
249771b8 | 2008 | |
96efedf1 KS |
2009 | static u64 syslog_seq; |
2010 | static u32 syslog_idx; | |
eab07260 KS |
2011 | static u64 console_seq; |
2012 | static u32 console_idx; | |
f92b070f | 2013 | static u64 exclusive_console_stop_seq; |
96efedf1 KS |
2014 | static u64 log_first_seq; |
2015 | static u32 log_first_idx; | |
2016 | static u64 log_next_seq; | |
6fe29354 TH |
2017 | static char *log_text(const struct printk_log *msg) { return NULL; } |
2018 | static char *log_dict(const struct printk_log *msg) { return NULL; } | |
62e32ac3 | 2019 | static struct printk_log *log_from_idx(u32 idx) { return NULL; } |
7f3a781d | 2020 | static u32 log_next(u32 idx) { return 0; } |
6fe29354 | 2021 | static ssize_t msg_print_ext_header(char *buf, size_t size, |
5aa068ea LT |
2022 | struct printk_log *msg, |
2023 | u64 seq) { return 0; } | |
6fe29354 TH |
2024 | static ssize_t msg_print_ext_body(char *buf, size_t size, |
2025 | char *dict, size_t dict_len, | |
2026 | char *text, size_t text_len) { return 0; } | |
c162d5b4 PM |
2027 | static void console_lock_spinning_enable(void) { } |
2028 | static int console_lock_spinning_disable_and_check(void) { return 0; } | |
d9c23523 | 2029 | static void call_console_drivers(const char *ext_text, size_t ext_len, |
6fe29354 | 2030 | const char *text, size_t len) {} |
5aa068ea | 2031 | static size_t msg_print_text(const struct printk_log *msg, |
5becfb1d | 2032 | bool syslog, char *buf, size_t size) { return 0; } |
a6ae928c | 2033 | static bool suppress_message_printing(int level) { return false; } |
d59745ce | 2034 | |
7f3a781d | 2035 | #endif /* CONFIG_PRINTK */ |
d59745ce | 2036 | |
d0380e6c TG |
2037 | #ifdef CONFIG_EARLY_PRINTK |
2038 | struct console *early_console; | |
2039 | ||
722a9f92 | 2040 | asmlinkage __visible void early_printk(const char *fmt, ...) |
d0380e6c TG |
2041 | { |
2042 | va_list ap; | |
1dc6244b JP |
2043 | char buf[512]; |
2044 | int n; | |
2045 | ||
2046 | if (!early_console) | |
2047 | return; | |
d0380e6c TG |
2048 | |
2049 | va_start(ap, fmt); | |
1dc6244b | 2050 | n = vscnprintf(buf, sizeof(buf), fmt, ap); |
d0380e6c | 2051 | va_end(ap); |
1dc6244b JP |
2052 | |
2053 | early_console->write(early_console, buf, n); | |
d0380e6c TG |
2054 | } |
2055 | #endif | |
2056 | ||
f7511d5f ST |
2057 | static int __add_preferred_console(char *name, int idx, char *options, |
2058 | char *brl_options) | |
2059 | { | |
2060 | struct console_cmdline *c; | |
2061 | int i; | |
2062 | ||
2063 | /* | |
2064 | * See if this tty is not yet registered, and | |
2065 | * if we have a slot free. | |
2066 | */ | |
dac8bbba PM |
2067 | for (i = 0, c = console_cmdline; |
2068 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2069 | i++, c++) { | |
23475408 | 2070 | if (strcmp(c->name, name) == 0 && c->index == idx) { |
dac8bbba PM |
2071 | if (!brl_options) |
2072 | preferred_console = i; | |
23475408 | 2073 | return 0; |
f7511d5f | 2074 | } |
23475408 | 2075 | } |
f7511d5f ST |
2076 | if (i == MAX_CMDLINECONSOLES) |
2077 | return -E2BIG; | |
2078 | if (!brl_options) | |
ad86ee2b | 2079 | preferred_console = i; |
f7511d5f ST |
2080 | strlcpy(c->name, name, sizeof(c->name)); |
2081 | c->options = options; | |
bbeddf52 JP |
2082 | braille_set_options(c, brl_options); |
2083 | ||
f7511d5f ST |
2084 | c->index = idx; |
2085 | return 0; | |
2086 | } | |
cca10d58 SS |
2087 | |
2088 | static int __init console_msg_format_setup(char *str) | |
2089 | { | |
2090 | if (!strcmp(str, "syslog")) | |
2091 | console_msg_format = MSG_FORMAT_SYSLOG; | |
2092 | if (!strcmp(str, "default")) | |
2093 | console_msg_format = MSG_FORMAT_DEFAULT; | |
2094 | return 1; | |
2095 | } | |
2096 | __setup("console_msg_format=", console_msg_format_setup); | |
2097 | ||
2ea1c539 | 2098 | /* |
0b90fec3 AE |
2099 | * Set up a console. Called via do_early_param() in init/main.c |
2100 | * for each "console=" parameter in the boot command line. | |
2ea1c539 JB |
2101 | */ |
2102 | static int __init console_setup(char *str) | |
2103 | { | |
0b90fec3 | 2104 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ |
f7511d5f | 2105 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
2106 | int idx; |
2107 | ||
bbeddf52 JP |
2108 | if (_braille_console_setup(&str, &brl_options)) |
2109 | return 1; | |
f7511d5f | 2110 | |
2ea1c539 JB |
2111 | /* |
2112 | * Decode str into name, index, options. | |
2113 | */ | |
2114 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
2115 | strcpy(buf, "ttyS"); |
2116 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 2117 | } else { |
eaa944af | 2118 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 2119 | } |
eaa944af | 2120 | buf[sizeof(buf) - 1] = 0; |
249771b8 AE |
2121 | options = strchr(str, ','); |
2122 | if (options) | |
2ea1c539 JB |
2123 | *(options++) = 0; |
2124 | #ifdef __sparc__ | |
2125 | if (!strcmp(str, "ttya")) | |
eaa944af | 2126 | strcpy(buf, "ttyS0"); |
2ea1c539 | 2127 | if (!strcmp(str, "ttyb")) |
eaa944af | 2128 | strcpy(buf, "ttyS1"); |
2ea1c539 | 2129 | #endif |
eaa944af | 2130 | for (s = buf; *s; s++) |
249771b8 | 2131 | if (isdigit(*s) || *s == ',') |
2ea1c539 JB |
2132 | break; |
2133 | idx = simple_strtoul(s, NULL, 10); | |
2134 | *s = 0; | |
2135 | ||
f7511d5f | 2136 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 2137 | console_set_on_cmdline = 1; |
2ea1c539 JB |
2138 | return 1; |
2139 | } | |
2140 | __setup("console=", console_setup); | |
2141 | ||
3c0547ba MM |
2142 | /** |
2143 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
2144 | * @name: device name |
2145 | * @idx: device index | |
2146 | * @options: options for this console | |
3c0547ba MM |
2147 | * |
2148 | * The last preferred console added will be used for kernel messages | |
2149 | * and stdin/out/err for init. Normally this is used by console_setup | |
2150 | * above to handle user-supplied console arguments; however it can also | |
2151 | * be used by arch-specific code either to override the user or more | |
2152 | * commonly to provide a default console (ie from PROM variables) when | |
2153 | * the user has not supplied one. | |
2154 | */ | |
fb445ee5 | 2155 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 2156 | { |
f7511d5f | 2157 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
2158 | } |
2159 | ||
d25d9fec | 2160 | bool console_suspend_enabled = true; |
8f4ce8c3 AS |
2161 | EXPORT_SYMBOL(console_suspend_enabled); |
2162 | ||
2163 | static int __init console_suspend_disable(char *str) | |
2164 | { | |
d25d9fec | 2165 | console_suspend_enabled = false; |
8f4ce8c3 AS |
2166 | return 1; |
2167 | } | |
2168 | __setup("no_console_suspend", console_suspend_disable); | |
134620f7 YZ |
2169 | module_param_named(console_suspend, console_suspend_enabled, |
2170 | bool, S_IRUGO | S_IWUSR); | |
2171 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" | |
2172 | " and hibernate operations"); | |
8f4ce8c3 | 2173 | |
557240b4 LT |
2174 | /** |
2175 | * suspend_console - suspend the console subsystem | |
2176 | * | |
2177 | * This disables printk() while we go into suspend states | |
2178 | */ | |
2179 | void suspend_console(void) | |
2180 | { | |
8f4ce8c3 AS |
2181 | if (!console_suspend_enabled) |
2182 | return; | |
47319f71 | 2183 | pr_info("Suspending console(s) (use no_console_suspend to debug)\n"); |
ac751efa | 2184 | console_lock(); |
557240b4 | 2185 | console_suspended = 1; |
bd8d7cf5 | 2186 | up_console_sem(); |
557240b4 LT |
2187 | } |
2188 | ||
2189 | void resume_console(void) | |
2190 | { | |
8f4ce8c3 AS |
2191 | if (!console_suspend_enabled) |
2192 | return; | |
bd8d7cf5 | 2193 | down_console_sem(); |
557240b4 | 2194 | console_suspended = 0; |
ac751efa | 2195 | console_unlock(); |
557240b4 LT |
2196 | } |
2197 | ||
034260d6 KC |
2198 | /** |
2199 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
90b14889 | 2200 | * @cpu: unused |
034260d6 KC |
2201 | * |
2202 | * If printk() is called from a CPU that is not online yet, the messages | |
64ca752d SS |
2203 | * will be printed on the console only if there are CON_ANYTIME consoles. |
2204 | * This function is called when a new CPU comes online (or fails to come | |
2205 | * up) or goes offline. | |
034260d6 | 2206 | */ |
90b14889 SAS |
2207 | static int console_cpu_notify(unsigned int cpu) |
2208 | { | |
f97960fb | 2209 | if (!cpuhp_tasks_frozen) { |
64ca752d SS |
2210 | /* If trylock fails, someone else is doing the printing */ |
2211 | if (console_trylock()) | |
2212 | console_unlock(); | |
034260d6 | 2213 | } |
90b14889 | 2214 | return 0; |
034260d6 KC |
2215 | } |
2216 | ||
1da177e4 | 2217 | /** |
ac751efa | 2218 | * console_lock - lock the console system for exclusive use. |
1da177e4 | 2219 | * |
ac751efa | 2220 | * Acquires a lock which guarantees that the caller has |
1da177e4 LT |
2221 | * exclusive access to the console system and the console_drivers list. |
2222 | * | |
2223 | * Can sleep, returns nothing. | |
2224 | */ | |
ac751efa | 2225 | void console_lock(void) |
1da177e4 | 2226 | { |
6b898c07 DV |
2227 | might_sleep(); |
2228 | ||
bd8d7cf5 | 2229 | down_console_sem(); |
403f3075 AH |
2230 | if (console_suspended) |
2231 | return; | |
1da177e4 LT |
2232 | console_locked = 1; |
2233 | console_may_schedule = 1; | |
2234 | } | |
ac751efa | 2235 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 2236 | |
ac751efa TH |
2237 | /** |
2238 | * console_trylock - try to lock the console system for exclusive use. | |
2239 | * | |
0b90fec3 AE |
2240 | * Try to acquire a lock which guarantees that the caller has exclusive |
2241 | * access to the console system and the console_drivers list. | |
ac751efa TH |
2242 | * |
2243 | * returns 1 on success, and 0 on failure to acquire the lock. | |
2244 | */ | |
2245 | int console_trylock(void) | |
1da177e4 | 2246 | { |
bd8d7cf5 | 2247 | if (down_trylock_console_sem()) |
ac751efa | 2248 | return 0; |
403f3075 | 2249 | if (console_suspended) { |
bd8d7cf5 | 2250 | up_console_sem(); |
ac751efa | 2251 | return 0; |
403f3075 | 2252 | } |
1da177e4 | 2253 | console_locked = 1; |
fd5f7cde | 2254 | console_may_schedule = 0; |
ac751efa | 2255 | return 1; |
1da177e4 | 2256 | } |
ac751efa | 2257 | EXPORT_SYMBOL(console_trylock); |
1da177e4 LT |
2258 | |
2259 | int is_console_locked(void) | |
2260 | { | |
2261 | return console_locked; | |
2262 | } | |
d48de54a | 2263 | EXPORT_SYMBOL(is_console_locked); |
1da177e4 | 2264 | |
a8199371 SS |
2265 | /* |
2266 | * Check if we have any console that is capable of printing while cpu is | |
2267 | * booting or shutting down. Requires console_sem. | |
2268 | */ | |
2269 | static int have_callable_console(void) | |
2270 | { | |
2271 | struct console *con; | |
2272 | ||
2273 | for_each_console(con) | |
adaf6590 SS |
2274 | if ((con->flags & CON_ENABLED) && |
2275 | (con->flags & CON_ANYTIME)) | |
a8199371 SS |
2276 | return 1; |
2277 | ||
2278 | return 0; | |
2279 | } | |
2280 | ||
2281 | /* | |
2282 | * Can we actually use the console at this time on this cpu? | |
2283 | * | |
2284 | * Console drivers may assume that per-cpu resources have been allocated. So | |
2285 | * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't | |
2286 | * call them until this CPU is officially up. | |
2287 | */ | |
2288 | static inline int can_use_console(void) | |
2289 | { | |
2290 | return cpu_online(raw_smp_processor_id()) || have_callable_console(); | |
2291 | } | |
2292 | ||
1da177e4 | 2293 | /** |
ac751efa | 2294 | * console_unlock - unlock the console system |
1da177e4 | 2295 | * |
ac751efa | 2296 | * Releases the console_lock which the caller holds on the console system |
1da177e4 LT |
2297 | * and the console driver list. |
2298 | * | |
ac751efa TH |
2299 | * While the console_lock was held, console output may have been buffered |
2300 | * by printk(). If this is the case, console_unlock(); emits | |
2301 | * the output prior to releasing the lock. | |
1da177e4 | 2302 | * |
7f3a781d | 2303 | * If there is output waiting, we wake /dev/kmsg and syslog() users. |
1da177e4 | 2304 | * |
ac751efa | 2305 | * console_unlock(); may be called from any context. |
1da177e4 | 2306 | */ |
ac751efa | 2307 | void console_unlock(void) |
1da177e4 | 2308 | { |
6fe29354 | 2309 | static char ext_text[CONSOLE_EXT_LOG_MAX]; |
70498253 | 2310 | static char text[LOG_LINE_MAX + PREFIX_MAX]; |
1da177e4 | 2311 | unsigned long flags; |
8d91f8b1 | 2312 | bool do_cond_resched, retry; |
1da177e4 | 2313 | |
557240b4 | 2314 | if (console_suspended) { |
bd8d7cf5 | 2315 | up_console_sem(); |
557240b4 LT |
2316 | return; |
2317 | } | |
78944e54 | 2318 | |
8d91f8b1 | 2319 | /* |
257ab443 | 2320 | * Console drivers are called with interrupts disabled, so |
8d91f8b1 TH |
2321 | * @console_may_schedule should be cleared before; however, we may |
2322 | * end up dumping a lot of lines, for example, if called from | |
2323 | * console registration path, and should invoke cond_resched() | |
2324 | * between lines if allowable. Not doing so can cause a very long | |
2325 | * scheduling stall on a slow console leading to RCU stall and | |
2326 | * softlockup warnings which exacerbate the issue with more | |
2327 | * messages practically incapacitating the system. | |
257ab443 PM |
2328 | * |
2329 | * console_trylock() is not able to detect the preemptive | |
2330 | * context reliably. Therefore the value must be stored before | |
2331 | * and cleared after the the "again" goto label. | |
8d91f8b1 TH |
2332 | */ |
2333 | do_cond_resched = console_may_schedule; | |
257ab443 | 2334 | again: |
78944e54 AD |
2335 | console_may_schedule = 0; |
2336 | ||
a8199371 SS |
2337 | /* |
2338 | * We released the console_sem lock, so we need to recheck if | |
2339 | * cpu is online and (if not) is there at least one CON_ANYTIME | |
2340 | * console. | |
2341 | */ | |
2342 | if (!can_use_console()) { | |
2343 | console_locked = 0; | |
2344 | up_console_sem(); | |
2345 | return; | |
2346 | } | |
2347 | ||
7ff9554b | 2348 | for (;;) { |
62e32ac3 | 2349 | struct printk_log *msg; |
6fe29354 | 2350 | size_t ext_len = 0; |
3ce9a7c0 | 2351 | size_t len; |
7ff9554b | 2352 | |
f975237b SS |
2353 | printk_safe_enter_irqsave(flags); |
2354 | raw_spin_lock(&logbuf_lock); | |
7ff9554b | 2355 | if (console_seq < log_first_seq) { |
51a72ab7 HZ |
2356 | len = sprintf(text, |
2357 | "** %llu printk messages dropped **\n", | |
2358 | log_first_seq - console_seq); | |
84b5ec8a | 2359 | |
7ff9554b KS |
2360 | /* messages are gone, move to first one */ |
2361 | console_seq = log_first_seq; | |
2362 | console_idx = log_first_idx; | |
84b5ec8a WD |
2363 | } else { |
2364 | len = 0; | |
7ff9554b | 2365 | } |
084681d1 | 2366 | skip: |
7ff9554b KS |
2367 | if (console_seq == log_next_seq) |
2368 | break; | |
2369 | ||
2370 | msg = log_from_idx(console_idx); | |
a6ae928c | 2371 | if (suppress_message_printing(msg->level)) { |
084681d1 | 2372 | /* |
a6ae928c PM |
2373 | * Skip record we have buffered and already printed |
2374 | * directly to the console when we received it, and | |
2375 | * record that has level above the console loglevel. | |
084681d1 KS |
2376 | */ |
2377 | console_idx = log_next(console_idx); | |
2378 | console_seq++; | |
2379 | goto skip; | |
2380 | } | |
649e6ee3 | 2381 | |
f92b070f PM |
2382 | /* Output to all consoles once old messages replayed. */ |
2383 | if (unlikely(exclusive_console && | |
2384 | console_seq >= exclusive_console_stop_seq)) { | |
2385 | exclusive_console = NULL; | |
2386 | } | |
2387 | ||
cca10d58 SS |
2388 | len += msg_print_text(msg, |
2389 | console_msg_format & MSG_FORMAT_SYSLOG, | |
2390 | text + len, | |
2391 | sizeof(text) - len); | |
6fe29354 TH |
2392 | if (nr_ext_console_drivers) { |
2393 | ext_len = msg_print_ext_header(ext_text, | |
2394 | sizeof(ext_text), | |
5aa068ea | 2395 | msg, console_seq); |
6fe29354 TH |
2396 | ext_len += msg_print_ext_body(ext_text + ext_len, |
2397 | sizeof(ext_text) - ext_len, | |
2398 | log_dict(msg), msg->dict_len, | |
2399 | log_text(msg), msg->text_len); | |
2400 | } | |
7ff9554b KS |
2401 | console_idx = log_next(console_idx); |
2402 | console_seq++; | |
07354eb1 | 2403 | raw_spin_unlock(&logbuf_lock); |
7ff9554b | 2404 | |
dbdda842 SRV |
2405 | /* |
2406 | * While actively printing out messages, if another printk() | |
2407 | * were to occur on another CPU, it may wait for this one to | |
2408 | * finish. This task can not be preempted if there is a | |
2409 | * waiter waiting to take over. | |
2410 | */ | |
c162d5b4 | 2411 | console_lock_spinning_enable(); |
dbdda842 | 2412 | |
81d68a96 | 2413 | stop_critical_timings(); /* don't trace print latency */ |
d9c23523 | 2414 | call_console_drivers(ext_text, ext_len, text, len); |
81d68a96 | 2415 | start_critical_timings(); |
dbdda842 | 2416 | |
c162d5b4 PM |
2417 | if (console_lock_spinning_disable_and_check()) { |
2418 | printk_safe_exit_irqrestore(flags); | |
43a17111 | 2419 | return; |
c162d5b4 | 2420 | } |
dbdda842 | 2421 | |
f975237b | 2422 | printk_safe_exit_irqrestore(flags); |
8d91f8b1 TH |
2423 | |
2424 | if (do_cond_resched) | |
2425 | cond_resched(); | |
1da177e4 | 2426 | } |
dbdda842 | 2427 | |
1da177e4 | 2428 | console_locked = 0; |
fe3d8ad3 | 2429 | |
07354eb1 | 2430 | raw_spin_unlock(&logbuf_lock); |
4f2a8d3c | 2431 | |
bd8d7cf5 | 2432 | up_console_sem(); |
4f2a8d3c PZ |
2433 | |
2434 | /* | |
2435 | * Someone could have filled up the buffer again, so re-check if there's | |
2436 | * something to flush. In case we cannot trylock the console_sem again, | |
2437 | * there's a new owner and the console_unlock() from them will do the | |
2438 | * flush, no worries. | |
2439 | */ | |
07354eb1 | 2440 | raw_spin_lock(&logbuf_lock); |
7ff9554b | 2441 | retry = console_seq != log_next_seq; |
f975237b SS |
2442 | raw_spin_unlock(&logbuf_lock); |
2443 | printk_safe_exit_irqrestore(flags); | |
09dc3cf9 | 2444 | |
4f2a8d3c PZ |
2445 | if (retry && console_trylock()) |
2446 | goto again; | |
1da177e4 | 2447 | } |
ac751efa | 2448 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 2449 | |
ddad86c2 MW |
2450 | /** |
2451 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
2452 | * |
2453 | * If the console code is currently allowed to sleep, and | |
2454 | * if this CPU should yield the CPU to another task, do | |
2455 | * so here. | |
2456 | * | |
ac751efa | 2457 | * Must be called within console_lock();. |
1da177e4 LT |
2458 | */ |
2459 | void __sched console_conditional_schedule(void) | |
2460 | { | |
2461 | if (console_may_schedule) | |
2462 | cond_resched(); | |
2463 | } | |
2464 | EXPORT_SYMBOL(console_conditional_schedule); | |
2465 | ||
1da177e4 LT |
2466 | void console_unblank(void) |
2467 | { | |
2468 | struct console *c; | |
2469 | ||
2470 | /* | |
2471 | * console_unblank can no longer be called in interrupt context unless | |
2472 | * oops_in_progress is set to 1.. | |
2473 | */ | |
2474 | if (oops_in_progress) { | |
bd8d7cf5 | 2475 | if (down_trylock_console_sem() != 0) |
1da177e4 LT |
2476 | return; |
2477 | } else | |
ac751efa | 2478 | console_lock(); |
1da177e4 LT |
2479 | |
2480 | console_locked = 1; | |
2481 | console_may_schedule = 0; | |
4d091611 | 2482 | for_each_console(c) |
1da177e4 LT |
2483 | if ((c->flags & CON_ENABLED) && c->unblank) |
2484 | c->unblank(); | |
ac751efa | 2485 | console_unlock(); |
1da177e4 | 2486 | } |
1da177e4 | 2487 | |
8d91f8b1 TH |
2488 | /** |
2489 | * console_flush_on_panic - flush console content on panic | |
2490 | * | |
2491 | * Immediately output all pending messages no matter what. | |
2492 | */ | |
2493 | void console_flush_on_panic(void) | |
2494 | { | |
2495 | /* | |
2496 | * If someone else is holding the console lock, trylock will fail | |
2497 | * and may_schedule may be set. Ignore and proceed to unlock so | |
2498 | * that messages are flushed out. As this can be called from any | |
2499 | * context and we don't want to get preempted while flushing, | |
2500 | * ensure may_schedule is cleared. | |
2501 | */ | |
2502 | console_trylock(); | |
2503 | console_may_schedule = 0; | |
2504 | console_unlock(); | |
2505 | } | |
2506 | ||
1da177e4 LT |
2507 | /* |
2508 | * Return the console tty driver structure and its associated index | |
2509 | */ | |
2510 | struct tty_driver *console_device(int *index) | |
2511 | { | |
2512 | struct console *c; | |
2513 | struct tty_driver *driver = NULL; | |
2514 | ||
ac751efa | 2515 | console_lock(); |
4d091611 | 2516 | for_each_console(c) { |
1da177e4 LT |
2517 | if (!c->device) |
2518 | continue; | |
2519 | driver = c->device(c, index); | |
2520 | if (driver) | |
2521 | break; | |
2522 | } | |
ac751efa | 2523 | console_unlock(); |
1da177e4 LT |
2524 | return driver; |
2525 | } | |
2526 | ||
2527 | /* | |
2528 | * Prevent further output on the passed console device so that (for example) | |
2529 | * serial drivers can disable console output before suspending a port, and can | |
2530 | * re-enable output afterwards. | |
2531 | */ | |
2532 | void console_stop(struct console *console) | |
2533 | { | |
ac751efa | 2534 | console_lock(); |
1da177e4 | 2535 | console->flags &= ~CON_ENABLED; |
ac751efa | 2536 | console_unlock(); |
1da177e4 LT |
2537 | } |
2538 | EXPORT_SYMBOL(console_stop); | |
2539 | ||
2540 | void console_start(struct console *console) | |
2541 | { | |
ac751efa | 2542 | console_lock(); |
1da177e4 | 2543 | console->flags |= CON_ENABLED; |
ac751efa | 2544 | console_unlock(); |
1da177e4 LT |
2545 | } |
2546 | EXPORT_SYMBOL(console_start); | |
2547 | ||
7bf69395 FDN |
2548 | static int __read_mostly keep_bootcon; |
2549 | ||
2550 | static int __init keep_bootcon_setup(char *str) | |
2551 | { | |
2552 | keep_bootcon = 1; | |
27083bac | 2553 | pr_info("debug: skip boot console de-registration.\n"); |
7bf69395 FDN |
2554 | |
2555 | return 0; | |
2556 | } | |
2557 | ||
2558 | early_param("keep_bootcon", keep_bootcon_setup); | |
2559 | ||
1da177e4 LT |
2560 | /* |
2561 | * The console driver calls this routine during kernel initialization | |
2562 | * to register the console printing procedure with printk() and to | |
2563 | * print any messages that were printed by the kernel before the | |
2564 | * console driver was initialized. | |
4d091611 RG |
2565 | * |
2566 | * This can happen pretty early during the boot process (because of | |
2567 | * early_printk) - sometimes before setup_arch() completes - be careful | |
2568 | * of what kernel features are used - they may not be initialised yet. | |
2569 | * | |
2570 | * There are two types of consoles - bootconsoles (early_printk) and | |
2571 | * "real" consoles (everything which is not a bootconsole) which are | |
2572 | * handled differently. | |
2573 | * - Any number of bootconsoles can be registered at any time. | |
2574 | * - As soon as a "real" console is registered, all bootconsoles | |
2575 | * will be unregistered automatically. | |
2576 | * - Once a "real" console is registered, any attempt to register a | |
2577 | * bootconsoles will be rejected | |
1da177e4 | 2578 | */ |
4d091611 | 2579 | void register_console(struct console *newcon) |
1da177e4 | 2580 | { |
40dc5651 | 2581 | int i; |
1da177e4 | 2582 | unsigned long flags; |
4d091611 | 2583 | struct console *bcon = NULL; |
23475408 | 2584 | struct console_cmdline *c; |
b077bafa | 2585 | static bool has_preferred; |
1da177e4 | 2586 | |
16cf48a6 AB |
2587 | if (console_drivers) |
2588 | for_each_console(bcon) | |
2589 | if (WARN(bcon == newcon, | |
2590 | "console '%s%d' already registered\n", | |
2591 | bcon->name, bcon->index)) | |
2592 | return; | |
2593 | ||
4d091611 RG |
2594 | /* |
2595 | * before we register a new CON_BOOT console, make sure we don't | |
2596 | * already have a valid console | |
2597 | */ | |
2598 | if (console_drivers && newcon->flags & CON_BOOT) { | |
2599 | /* find the last or real console */ | |
2600 | for_each_console(bcon) { | |
2601 | if (!(bcon->flags & CON_BOOT)) { | |
27083bac | 2602 | pr_info("Too late to register bootconsole %s%d\n", |
4d091611 RG |
2603 | newcon->name, newcon->index); |
2604 | return; | |
2605 | } | |
2606 | } | |
69331af7 GH |
2607 | } |
2608 | ||
4d091611 RG |
2609 | if (console_drivers && console_drivers->flags & CON_BOOT) |
2610 | bcon = console_drivers; | |
2611 | ||
b077bafa | 2612 | if (!has_preferred || bcon || !console_drivers) |
ad86ee2b | 2613 | has_preferred = preferred_console >= 0; |
1da177e4 LT |
2614 | |
2615 | /* | |
2616 | * See if we want to use this console driver. If we | |
2617 | * didn't select a console we take the first one | |
2618 | * that registers here. | |
2619 | */ | |
b077bafa | 2620 | if (!has_preferred) { |
4d091611 RG |
2621 | if (newcon->index < 0) |
2622 | newcon->index = 0; | |
2623 | if (newcon->setup == NULL || | |
2624 | newcon->setup(newcon, NULL) == 0) { | |
2625 | newcon->flags |= CON_ENABLED; | |
2626 | if (newcon->device) { | |
2627 | newcon->flags |= CON_CONSDEV; | |
b077bafa | 2628 | has_preferred = true; |
cd3a1b85 | 2629 | } |
1da177e4 LT |
2630 | } |
2631 | } | |
2632 | ||
2633 | /* | |
dac8bbba PM |
2634 | * See if this console matches one we selected on |
2635 | * the command line. | |
1da177e4 | 2636 | */ |
dac8bbba PM |
2637 | for (i = 0, c = console_cmdline; |
2638 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2639 | i++, c++) { | |
c7cef0a8 PH |
2640 | if (!newcon->match || |
2641 | newcon->match(newcon, c->name, c->index, c->options) != 0) { | |
2642 | /* default matching */ | |
2643 | BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name)); | |
2644 | if (strcmp(c->name, newcon->name) != 0) | |
2645 | continue; | |
2646 | if (newcon->index >= 0 && | |
2647 | newcon->index != c->index) | |
2648 | continue; | |
2649 | if (newcon->index < 0) | |
2650 | newcon->index = c->index; | |
bbeddf52 | 2651 | |
c7cef0a8 PH |
2652 | if (_braille_register_console(newcon, c)) |
2653 | return; | |
2654 | ||
2655 | if (newcon->setup && | |
2656 | newcon->setup(newcon, c->options) != 0) | |
2657 | break; | |
2658 | } | |
bbeddf52 | 2659 | |
4d091611 | 2660 | newcon->flags |= CON_ENABLED; |
ad86ee2b | 2661 | if (i == preferred_console) { |
4d091611 | 2662 | newcon->flags |= CON_CONSDEV; |
b077bafa | 2663 | has_preferred = true; |
ab4af03a | 2664 | } |
1da177e4 LT |
2665 | break; |
2666 | } | |
2667 | ||
4d091611 | 2668 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
2669 | return; |
2670 | ||
8259cf43 RG |
2671 | /* |
2672 | * If we have a bootconsole, and are switching to a real console, | |
2673 | * don't print everything out again, since when the boot console, and | |
2674 | * the real console are the same physical device, it's annoying to | |
2675 | * see the beginning boot messages twice | |
2676 | */ | |
2677 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 2678 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
2679 | |
2680 | /* | |
2681 | * Put this console in the list - keep the | |
2682 | * preferred driver at the head of the list. | |
2683 | */ | |
ac751efa | 2684 | console_lock(); |
4d091611 RG |
2685 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
2686 | newcon->next = console_drivers; | |
2687 | console_drivers = newcon; | |
2688 | if (newcon->next) | |
2689 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 2690 | } else { |
4d091611 RG |
2691 | newcon->next = console_drivers->next; |
2692 | console_drivers->next = newcon; | |
1da177e4 | 2693 | } |
6fe29354 TH |
2694 | |
2695 | if (newcon->flags & CON_EXTENDED) | |
9627808d | 2696 | nr_ext_console_drivers++; |
6fe29354 | 2697 | |
4d091611 | 2698 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 | 2699 | /* |
ac751efa | 2700 | * console_unlock(); will print out the buffered messages |
1da177e4 LT |
2701 | * for us. |
2702 | */ | |
de6fcbdb | 2703 | logbuf_lock_irqsave(flags); |
7ff9554b KS |
2704 | console_seq = syslog_seq; |
2705 | console_idx = syslog_idx; | |
fe3d8ad3 FT |
2706 | /* |
2707 | * We're about to replay the log buffer. Only do this to the | |
2708 | * just-registered console to avoid excessive message spam to | |
2709 | * the already-registered consoles. | |
884e370e SS |
2710 | * |
2711 | * Set exclusive_console with disabled interrupts to reduce | |
2712 | * race window with eventual console_flush_on_panic() that | |
2713 | * ignores console_lock. | |
fe3d8ad3 FT |
2714 | */ |
2715 | exclusive_console = newcon; | |
f92b070f | 2716 | exclusive_console_stop_seq = console_seq; |
884e370e | 2717 | logbuf_unlock_irqrestore(flags); |
1da177e4 | 2718 | } |
ac751efa | 2719 | console_unlock(); |
fbc92a34 | 2720 | console_sysfs_notify(); |
8259cf43 RG |
2721 | |
2722 | /* | |
2723 | * By unregistering the bootconsoles after we enable the real console | |
2724 | * we get the "console xxx enabled" message on all the consoles - | |
2725 | * boot consoles, real consoles, etc - this is to ensure that end | |
2726 | * users know there might be something in the kernel's log buffer that | |
2727 | * went to the bootconsole (that they do not see on the real console) | |
2728 | */ | |
27083bac | 2729 | pr_info("%sconsole [%s%d] enabled\n", |
6b802394 KC |
2730 | (newcon->flags & CON_BOOT) ? "boot" : "" , |
2731 | newcon->name, newcon->index); | |
7bf69395 FDN |
2732 | if (bcon && |
2733 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && | |
2734 | !keep_bootcon) { | |
6b802394 KC |
2735 | /* We need to iterate through all boot consoles, to make |
2736 | * sure we print everything out, before we unregister them. | |
8259cf43 | 2737 | */ |
8259cf43 RG |
2738 | for_each_console(bcon) |
2739 | if (bcon->flags & CON_BOOT) | |
2740 | unregister_console(bcon); | |
8259cf43 | 2741 | } |
1da177e4 LT |
2742 | } |
2743 | EXPORT_SYMBOL(register_console); | |
2744 | ||
40dc5651 | 2745 | int unregister_console(struct console *console) |
1da177e4 | 2746 | { |
40dc5651 | 2747 | struct console *a, *b; |
bbeddf52 | 2748 | int res; |
1da177e4 | 2749 | |
27083bac | 2750 | pr_info("%sconsole [%s%d] disabled\n", |
6b802394 KC |
2751 | (console->flags & CON_BOOT) ? "boot" : "" , |
2752 | console->name, console->index); | |
2753 | ||
bbeddf52 JP |
2754 | res = _braille_unregister_console(console); |
2755 | if (res) | |
2756 | return res; | |
f7511d5f | 2757 | |
bbeddf52 | 2758 | res = 1; |
ac751efa | 2759 | console_lock(); |
1da177e4 LT |
2760 | if (console_drivers == console) { |
2761 | console_drivers=console->next; | |
2762 | res = 0; | |
e9b15b54 | 2763 | } else if (console_drivers) { |
1da177e4 LT |
2764 | for (a=console_drivers->next, b=console_drivers ; |
2765 | a; b=a, a=b->next) { | |
2766 | if (a == console) { | |
2767 | b->next = a->next; | |
2768 | res = 0; | |
2769 | break; | |
40dc5651 | 2770 | } |
1da177e4 LT |
2771 | } |
2772 | } | |
40dc5651 | 2773 | |
6fe29354 TH |
2774 | if (!res && (console->flags & CON_EXTENDED)) |
2775 | nr_ext_console_drivers--; | |
2776 | ||
69331af7 | 2777 | /* |
ab4af03a GE |
2778 | * If this isn't the last console and it has CON_CONSDEV set, we |
2779 | * need to set it on the next preferred console. | |
1da177e4 | 2780 | */ |
69331af7 | 2781 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 2782 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 | 2783 | |
7fa21dd8 | 2784 | console->flags &= ~CON_ENABLED; |
ac751efa | 2785 | console_unlock(); |
fbc92a34 | 2786 | console_sysfs_notify(); |
1da177e4 LT |
2787 | return res; |
2788 | } | |
2789 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 2790 | |
0c688614 NP |
2791 | /* |
2792 | * Initialize the console device. This is called *early*, so | |
2793 | * we can't necessarily depend on lots of kernel help here. | |
2794 | * Just do some early initializations, and do the complex setup | |
2795 | * later. | |
2796 | */ | |
2797 | void __init console_init(void) | |
2798 | { | |
58eacfff | 2799 | int ret; |
1b1eeca7 AB |
2800 | initcall_t call; |
2801 | initcall_entry_t *ce; | |
0c688614 NP |
2802 | |
2803 | /* Setup the default TTY line discipline. */ | |
2804 | n_tty_init(); | |
2805 | ||
2806 | /* | |
2807 | * set up the console device so that later boot sequences can | |
2808 | * inform about problems etc.. | |
2809 | */ | |
1b1eeca7 | 2810 | ce = __con_initcall_start; |
58eacfff | 2811 | trace_initcall_level("console"); |
1b1eeca7 AB |
2812 | while (ce < __con_initcall_end) { |
2813 | call = initcall_from_entry(ce); | |
2814 | trace_initcall_start(call); | |
2815 | ret = call(); | |
2816 | trace_initcall_finish(call, ret); | |
2817 | ce++; | |
0c688614 NP |
2818 | } |
2819 | } | |
2820 | ||
81cc26f2 TR |
2821 | /* |
2822 | * Some boot consoles access data that is in the init section and which will | |
2823 | * be discarded after the initcalls have been run. To make sure that no code | |
2824 | * will access this data, unregister the boot consoles in a late initcall. | |
2825 | * | |
2826 | * If for some reason, such as deferred probe or the driver being a loadable | |
2827 | * module, the real console hasn't registered yet at this point, there will | |
2828 | * be a brief interval in which no messages are logged to the console, which | |
2829 | * makes it difficult to diagnose problems that occur during this time. | |
2830 | * | |
2831 | * To mitigate this problem somewhat, only unregister consoles whose memory | |
2b1be689 MR |
2832 | * intersects with the init section. Note that all other boot consoles will |
2833 | * get unregistred when the real preferred console is registered. | |
81cc26f2 | 2834 | */ |
034260d6 | 2835 | static int __init printk_late_init(void) |
0c5564bd | 2836 | { |
4d091611 | 2837 | struct console *con; |
90b14889 | 2838 | int ret; |
4d091611 RG |
2839 | |
2840 | for_each_console(con) { | |
5a814231 PM |
2841 | if (!(con->flags & CON_BOOT)) |
2842 | continue; | |
2843 | ||
2844 | /* Check addresses that might be used for enabled consoles. */ | |
2845 | if (init_section_intersects(con, sizeof(*con)) || | |
2846 | init_section_contains(con->write, 0) || | |
2847 | init_section_contains(con->read, 0) || | |
2848 | init_section_contains(con->device, 0) || | |
2849 | init_section_contains(con->unblank, 0) || | |
2850 | init_section_contains(con->data, 0)) { | |
81cc26f2 | 2851 | /* |
2b1be689 MR |
2852 | * Please, consider moving the reported consoles out |
2853 | * of the init section. | |
81cc26f2 | 2854 | */ |
2b1be689 MR |
2855 | pr_warn("bootconsole [%s%d] uses init memory and must be disabled even before the real one is ready\n", |
2856 | con->name, con->index); | |
2857 | unregister_console(con); | |
cb00e99c | 2858 | } |
0c5564bd | 2859 | } |
90b14889 SAS |
2860 | ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL, |
2861 | console_cpu_notify); | |
2862 | WARN_ON(ret < 0); | |
2863 | ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "printk:online", | |
2864 | console_cpu_notify, NULL); | |
2865 | WARN_ON(ret < 0); | |
0c5564bd RG |
2866 | return 0; |
2867 | } | |
034260d6 | 2868 | late_initcall(printk_late_init); |
0c5564bd | 2869 | |
7ef3d2fd | 2870 | #if defined CONFIG_PRINTK |
dc72c32e FW |
2871 | /* |
2872 | * Delayed printk version, for scheduler-internal messages: | |
2873 | */ | |
dc72c32e | 2874 | #define PRINTK_PENDING_WAKEUP 0x01 |
458df9fd | 2875 | #define PRINTK_PENDING_OUTPUT 0x02 |
dc72c32e FW |
2876 | |
2877 | static DEFINE_PER_CPU(int, printk_pending); | |
dc72c32e FW |
2878 | |
2879 | static void wake_up_klogd_work_func(struct irq_work *irq_work) | |
2880 | { | |
2881 | int pending = __this_cpu_xchg(printk_pending, 0); | |
2882 | ||
458df9fd SR |
2883 | if (pending & PRINTK_PENDING_OUTPUT) { |
2884 | /* If trylock fails, someone else is doing the printing */ | |
2885 | if (console_trylock()) | |
2886 | console_unlock(); | |
dc72c32e FW |
2887 | } |
2888 | ||
2889 | if (pending & PRINTK_PENDING_WAKEUP) | |
2890 | wake_up_interruptible(&log_wait); | |
2891 | } | |
2892 | ||
2893 | static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { | |
2894 | .func = wake_up_klogd_work_func, | |
2895 | .flags = IRQ_WORK_LAZY, | |
2896 | }; | |
2897 | ||
2898 | void wake_up_klogd(void) | |
2899 | { | |
2900 | preempt_disable(); | |
2901 | if (waitqueue_active(&log_wait)) { | |
2902 | this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); | |
bb964a92 | 2903 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
dc72c32e FW |
2904 | } |
2905 | preempt_enable(); | |
2906 | } | |
717115e1 | 2907 | |
a338f84d | 2908 | void defer_console_output(void) |
600e1458 | 2909 | { |
719f6a70 | 2910 | preempt_disable(); |
458df9fd | 2911 | __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); |
bb964a92 | 2912 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
81954606 | 2913 | preempt_enable(); |
a338f84d PM |
2914 | } |
2915 | ||
2916 | int vprintk_deferred(const char *fmt, va_list args) | |
2917 | { | |
2918 | int r; | |
2919 | ||
2920 | r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args); | |
2921 | defer_console_output(); | |
600e1458 PZ |
2922 | |
2923 | return r; | |
2924 | } | |
2925 | ||
719f6a70 PM |
2926 | int printk_deferred(const char *fmt, ...) |
2927 | { | |
2928 | va_list args; | |
2929 | int r; | |
2930 | ||
2931 | va_start(args, fmt); | |
2932 | r = vprintk_deferred(fmt, args); | |
2933 | va_end(args); | |
2934 | ||
2935 | return r; | |
2936 | } | |
2937 | ||
1da177e4 LT |
2938 | /* |
2939 | * printk rate limiting, lifted from the networking subsystem. | |
2940 | * | |
641de9d8 UKK |
2941 | * This enforces a rate limit: not more than 10 kernel messages |
2942 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 2943 | */ |
641de9d8 UKK |
2944 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
2945 | ||
5c828713 | 2946 | int __printk_ratelimit(const char *func) |
1da177e4 | 2947 | { |
5c828713 | 2948 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 2949 | } |
5c828713 | 2950 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
2951 | |
2952 | /** | |
2953 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
2954 | * @caller_jiffies: pointer to caller's state | |
2955 | * @interval_msecs: minimum interval between prints | |
2956 | * | |
2957 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
2958 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
2959 | * returned true. | |
2960 | */ | |
2961 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
2962 | unsigned int interval_msecs) | |
2963 | { | |
249771b8 AE |
2964 | unsigned long elapsed = jiffies - *caller_jiffies; |
2965 | ||
2966 | if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) | |
2967 | return false; | |
2968 | ||
2969 | *caller_jiffies = jiffies; | |
2970 | return true; | |
f46c4833 AM |
2971 | } |
2972 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
2973 | |
2974 | static DEFINE_SPINLOCK(dump_list_lock); | |
2975 | static LIST_HEAD(dump_list); | |
2976 | ||
2977 | /** | |
2978 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 2979 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
2980 | * |
2981 | * Adds a kernel log dumper to the system. The dump callback in the | |
2982 | * structure will be called when the kernel oopses or panics and must be | |
2983 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
2984 | */ | |
2985 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
2986 | { | |
2987 | unsigned long flags; | |
2988 | int err = -EBUSY; | |
2989 | ||
2990 | /* The dump callback needs to be set */ | |
2991 | if (!dumper->dump) | |
2992 | return -EINVAL; | |
2993 | ||
2994 | spin_lock_irqsave(&dump_list_lock, flags); | |
2995 | /* Don't allow registering multiple times */ | |
2996 | if (!dumper->registered) { | |
2997 | dumper->registered = 1; | |
fb842b00 | 2998 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
2999 | err = 0; |
3000 | } | |
3001 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
3002 | ||
3003 | return err; | |
3004 | } | |
3005 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
3006 | ||
3007 | /** | |
3008 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 3009 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
3010 | * |
3011 | * Removes a dump device from the system. Returns zero on success and | |
3012 | * %-EINVAL otherwise. | |
3013 | */ | |
3014 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
3015 | { | |
3016 | unsigned long flags; | |
3017 | int err = -EINVAL; | |
3018 | ||
3019 | spin_lock_irqsave(&dump_list_lock, flags); | |
3020 | if (dumper->registered) { | |
3021 | dumper->registered = 0; | |
fb842b00 | 3022 | list_del_rcu(&dumper->list); |
456b565c SK |
3023 | err = 0; |
3024 | } | |
3025 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 3026 | synchronize_rcu(); |
456b565c SK |
3027 | |
3028 | return err; | |
3029 | } | |
3030 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
3031 | ||
7ff9554b KS |
3032 | static bool always_kmsg_dump; |
3033 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); | |
3034 | ||
456b565c SK |
3035 | /** |
3036 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
3037 | * @reason: the reason (oops, panic etc) for dumping | |
3038 | * | |
e2ae715d KS |
3039 | * Call each of the registered dumper's dump() callback, which can |
3040 | * retrieve the kmsg records with kmsg_dump_get_line() or | |
3041 | * kmsg_dump_get_buffer(). | |
456b565c SK |
3042 | */ |
3043 | void kmsg_dump(enum kmsg_dump_reason reason) | |
3044 | { | |
456b565c | 3045 | struct kmsg_dumper *dumper; |
456b565c SK |
3046 | unsigned long flags; |
3047 | ||
c22ab332 MG |
3048 | if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump) |
3049 | return; | |
3050 | ||
e2ae715d KS |
3051 | rcu_read_lock(); |
3052 | list_for_each_entry_rcu(dumper, &dump_list, list) { | |
3053 | if (dumper->max_reason && reason > dumper->max_reason) | |
3054 | continue; | |
3055 | ||
3056 | /* initialize iterator with data about the stored records */ | |
3057 | dumper->active = true; | |
3058 | ||
de6fcbdb | 3059 | logbuf_lock_irqsave(flags); |
e2ae715d KS |
3060 | dumper->cur_seq = clear_seq; |
3061 | dumper->cur_idx = clear_idx; | |
3062 | dumper->next_seq = log_next_seq; | |
3063 | dumper->next_idx = log_next_idx; | |
de6fcbdb | 3064 | logbuf_unlock_irqrestore(flags); |
e2ae715d KS |
3065 | |
3066 | /* invoke dumper which will iterate over records */ | |
3067 | dumper->dump(dumper, reason); | |
3068 | ||
3069 | /* reset iterator */ | |
3070 | dumper->active = false; | |
3071 | } | |
3072 | rcu_read_unlock(); | |
3073 | } | |
3074 | ||
3075 | /** | |
533827c9 | 3076 | * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version) |
e2ae715d KS |
3077 | * @dumper: registered kmsg dumper |
3078 | * @syslog: include the "<4>" prefixes | |
3079 | * @line: buffer to copy the line to | |
3080 | * @size: maximum size of the buffer | |
3081 | * @len: length of line placed into buffer | |
3082 | * | |
3083 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
3084 | * record, and copy one record into the provided buffer. | |
3085 | * | |
3086 | * Consecutive calls will return the next available record moving | |
3087 | * towards the end of the buffer with the youngest messages. | |
3088 | * | |
3089 | * A return value of FALSE indicates that there are no more records to | |
3090 | * read. | |
533827c9 AV |
3091 | * |
3092 | * The function is similar to kmsg_dump_get_line(), but grabs no locks. | |
e2ae715d | 3093 | */ |
533827c9 AV |
3094 | bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog, |
3095 | char *line, size_t size, size_t *len) | |
e2ae715d | 3096 | { |
62e32ac3 | 3097 | struct printk_log *msg; |
e2ae715d KS |
3098 | size_t l = 0; |
3099 | bool ret = false; | |
3100 | ||
3101 | if (!dumper->active) | |
3102 | goto out; | |
7ff9554b | 3103 | |
e2ae715d KS |
3104 | if (dumper->cur_seq < log_first_seq) { |
3105 | /* messages are gone, move to first available one */ | |
3106 | dumper->cur_seq = log_first_seq; | |
3107 | dumper->cur_idx = log_first_idx; | |
3108 | } | |
456b565c | 3109 | |
e2ae715d | 3110 | /* last entry */ |
533827c9 | 3111 | if (dumper->cur_seq >= log_next_seq) |
e2ae715d | 3112 | goto out; |
456b565c | 3113 | |
e2ae715d | 3114 | msg = log_from_idx(dumper->cur_idx); |
5aa068ea | 3115 | l = msg_print_text(msg, syslog, line, size); |
e2ae715d KS |
3116 | |
3117 | dumper->cur_idx = log_next(dumper->cur_idx); | |
3118 | dumper->cur_seq++; | |
3119 | ret = true; | |
e2ae715d KS |
3120 | out: |
3121 | if (len) | |
3122 | *len = l; | |
3123 | return ret; | |
3124 | } | |
533827c9 AV |
3125 | |
3126 | /** | |
3127 | * kmsg_dump_get_line - retrieve one kmsg log line | |
3128 | * @dumper: registered kmsg dumper | |
3129 | * @syslog: include the "<4>" prefixes | |
3130 | * @line: buffer to copy the line to | |
3131 | * @size: maximum size of the buffer | |
3132 | * @len: length of line placed into buffer | |
3133 | * | |
3134 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
3135 | * record, and copy one record into the provided buffer. | |
3136 | * | |
3137 | * Consecutive calls will return the next available record moving | |
3138 | * towards the end of the buffer with the youngest messages. | |
3139 | * | |
3140 | * A return value of FALSE indicates that there are no more records to | |
3141 | * read. | |
3142 | */ | |
3143 | bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, | |
3144 | char *line, size_t size, size_t *len) | |
3145 | { | |
3146 | unsigned long flags; | |
3147 | bool ret; | |
3148 | ||
de6fcbdb | 3149 | logbuf_lock_irqsave(flags); |
533827c9 | 3150 | ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len); |
de6fcbdb | 3151 | logbuf_unlock_irqrestore(flags); |
533827c9 AV |
3152 | |
3153 | return ret; | |
3154 | } | |
e2ae715d KS |
3155 | EXPORT_SYMBOL_GPL(kmsg_dump_get_line); |
3156 | ||
3157 | /** | |
3158 | * kmsg_dump_get_buffer - copy kmsg log lines | |
3159 | * @dumper: registered kmsg dumper | |
3160 | * @syslog: include the "<4>" prefixes | |
4f0f4af5 | 3161 | * @buf: buffer to copy the line to |
e2ae715d KS |
3162 | * @size: maximum size of the buffer |
3163 | * @len: length of line placed into buffer | |
3164 | * | |
3165 | * Start at the end of the kmsg buffer and fill the provided buffer | |
3166 | * with as many of the the *youngest* kmsg records that fit into it. | |
3167 | * If the buffer is large enough, all available kmsg records will be | |
3168 | * copied with a single call. | |
3169 | * | |
3170 | * Consecutive calls will fill the buffer with the next block of | |
3171 | * available older records, not including the earlier retrieved ones. | |
3172 | * | |
3173 | * A return value of FALSE indicates that there are no more records to | |
3174 | * read. | |
3175 | */ | |
3176 | bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, | |
3177 | char *buf, size_t size, size_t *len) | |
3178 | { | |
3179 | unsigned long flags; | |
3180 | u64 seq; | |
3181 | u32 idx; | |
3182 | u64 next_seq; | |
3183 | u32 next_idx; | |
3184 | size_t l = 0; | |
3185 | bool ret = false; | |
3186 | ||
3187 | if (!dumper->active) | |
3188 | goto out; | |
3189 | ||
de6fcbdb | 3190 | logbuf_lock_irqsave(flags); |
e2ae715d KS |
3191 | if (dumper->cur_seq < log_first_seq) { |
3192 | /* messages are gone, move to first available one */ | |
3193 | dumper->cur_seq = log_first_seq; | |
3194 | dumper->cur_idx = log_first_idx; | |
3195 | } | |
3196 | ||
3197 | /* last entry */ | |
3198 | if (dumper->cur_seq >= dumper->next_seq) { | |
de6fcbdb | 3199 | logbuf_unlock_irqrestore(flags); |
e2ae715d KS |
3200 | goto out; |
3201 | } | |
3202 | ||
3203 | /* calculate length of entire buffer */ | |
3204 | seq = dumper->cur_seq; | |
3205 | idx = dumper->cur_idx; | |
3206 | while (seq < dumper->next_seq) { | |
62e32ac3 | 3207 | struct printk_log *msg = log_from_idx(idx); |
e2ae715d | 3208 | |
5aa068ea | 3209 | l += msg_print_text(msg, true, NULL, 0); |
e2ae715d KS |
3210 | idx = log_next(idx); |
3211 | seq++; | |
3212 | } | |
3213 | ||
3214 | /* move first record forward until length fits into the buffer */ | |
3215 | seq = dumper->cur_seq; | |
3216 | idx = dumper->cur_idx; | |
3217 | while (l > size && seq < dumper->next_seq) { | |
62e32ac3 | 3218 | struct printk_log *msg = log_from_idx(idx); |
456b565c | 3219 | |
5aa068ea | 3220 | l -= msg_print_text(msg, true, NULL, 0); |
e2ae715d KS |
3221 | idx = log_next(idx); |
3222 | seq++; | |
456b565c | 3223 | } |
e2ae715d KS |
3224 | |
3225 | /* last message in next interation */ | |
3226 | next_seq = seq; | |
3227 | next_idx = idx; | |
3228 | ||
3229 | l = 0; | |
3230 | while (seq < dumper->next_seq) { | |
62e32ac3 | 3231 | struct printk_log *msg = log_from_idx(idx); |
e2ae715d | 3232 | |
5aa068ea | 3233 | l += msg_print_text(msg, syslog, buf + l, size - l); |
e2ae715d KS |
3234 | idx = log_next(idx); |
3235 | seq++; | |
3236 | } | |
3237 | ||
3238 | dumper->next_seq = next_seq; | |
3239 | dumper->next_idx = next_idx; | |
3240 | ret = true; | |
de6fcbdb | 3241 | logbuf_unlock_irqrestore(flags); |
e2ae715d KS |
3242 | out: |
3243 | if (len) | |
3244 | *len = l; | |
3245 | return ret; | |
3246 | } | |
3247 | EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); | |
456b565c | 3248 | |
533827c9 AV |
3249 | /** |
3250 | * kmsg_dump_rewind_nolock - reset the interator (unlocked version) | |
3251 | * @dumper: registered kmsg dumper | |
3252 | * | |
3253 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
3254 | * kmsg_dump_get_buffer() can be called again and used multiple | |
3255 | * times within the same dumper.dump() callback. | |
3256 | * | |
3257 | * The function is similar to kmsg_dump_rewind(), but grabs no locks. | |
3258 | */ | |
3259 | void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper) | |
3260 | { | |
3261 | dumper->cur_seq = clear_seq; | |
3262 | dumper->cur_idx = clear_idx; | |
3263 | dumper->next_seq = log_next_seq; | |
3264 | dumper->next_idx = log_next_idx; | |
3265 | } | |
3266 | ||
e2ae715d KS |
3267 | /** |
3268 | * kmsg_dump_rewind - reset the interator | |
3269 | * @dumper: registered kmsg dumper | |
3270 | * | |
3271 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
3272 | * kmsg_dump_get_buffer() can be called again and used multiple | |
3273 | * times within the same dumper.dump() callback. | |
3274 | */ | |
3275 | void kmsg_dump_rewind(struct kmsg_dumper *dumper) | |
3276 | { | |
3277 | unsigned long flags; | |
3278 | ||
de6fcbdb | 3279 | logbuf_lock_irqsave(flags); |
533827c9 | 3280 | kmsg_dump_rewind_nolock(dumper); |
de6fcbdb | 3281 | logbuf_unlock_irqrestore(flags); |
456b565c | 3282 | } |
e2ae715d | 3283 | EXPORT_SYMBOL_GPL(kmsg_dump_rewind); |
196779b9 | 3284 | |
7ef3d2fd | 3285 | #endif |