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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * linux/kernel/printk.c | |
4 | * | |
5 | * Copyright (C) 1991, 1992 Linus Torvalds | |
6 | * | |
7 | * Modified to make sys_syslog() more flexible: added commands to | |
8 | * return the last 4k of kernel messages, regardless of whether | |
9 | * they've been read or not. Added option to suppress kernel printk's | |
10 | * to the console. Added hook for sending the console messages | |
11 | * elsewhere, in preparation for a serial line console (someday). | |
12 | * Ted Ts'o, 2/11/93. | |
13 | * Modified for sysctl support, 1/8/97, Chris Horn. | |
40dc5651 | 14 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 15 | * manfred@colorfullife.com |
1da177e4 | 16 | * Rewrote bits to get rid of console_lock |
e1f8e874 | 17 | * 01Mar01 Andrew Morton |
1da177e4 LT |
18 | */ |
19 | ||
dd5adbfb HZ |
20 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
21 | ||
1da177e4 LT |
22 | #include <linux/kernel.h> |
23 | #include <linux/mm.h> | |
24 | #include <linux/tty.h> | |
25 | #include <linux/tty_driver.h> | |
1da177e4 LT |
26 | #include <linux/console.h> |
27 | #include <linux/init.h> | |
bfe8df3d RD |
28 | #include <linux/jiffies.h> |
29 | #include <linux/nmi.h> | |
1da177e4 | 30 | #include <linux/module.h> |
3b9c0410 | 31 | #include <linux/moduleparam.h> |
1da177e4 LT |
32 | #include <linux/delay.h> |
33 | #include <linux/smp.h> | |
34 | #include <linux/security.h> | |
162a7e75 | 35 | #include <linux/memblock.h> |
1da177e4 | 36 | #include <linux/syscalls.h> |
692f66f2 | 37 | #include <linux/crash_core.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 | ||
896fbe20 | 58 | #include "printk_ringbuffer.h" |
d197c43d | 59 | #include "console_cmdline.h" |
bbeddf52 | 60 | #include "braille.h" |
42a0bb3f | 61 | #include "internal.h" |
d197c43d | 62 | |
1da177e4 | 63 | int console_printk[4] = { |
a8fe19eb | 64 | CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */ |
42a9dc0b | 65 | MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */ |
a8fe19eb BP |
66 | CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */ |
67 | CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ | |
1da177e4 | 68 | }; |
a1939185 | 69 | EXPORT_SYMBOL_GPL(console_printk); |
1da177e4 | 70 | |
56e6c104 TZ |
71 | atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0); |
72 | EXPORT_SYMBOL(ignore_console_lock_warning); | |
73 | ||
1da177e4 | 74 | /* |
0bbfb7c2 | 75 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
76 | * their unblank() callback or not. So let's export it. |
77 | */ | |
78 | int oops_in_progress; | |
79 | EXPORT_SYMBOL(oops_in_progress); | |
80 | ||
81 | /* | |
82 | * console_sem protects the console_drivers list, and also | |
83 | * provides serialisation for access to the entire console | |
84 | * driver system. | |
85 | */ | |
5b8c4f23 | 86 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 87 | struct console *console_drivers; |
a29d1cfe IM |
88 | EXPORT_SYMBOL_GPL(console_drivers); |
89 | ||
c39ea0b9 FT |
90 | /* |
91 | * System may need to suppress printk message under certain | |
92 | * circumstances, like after kernel panic happens. | |
93 | */ | |
94 | int __read_mostly suppress_printk; | |
95 | ||
daee7797 DV |
96 | #ifdef CONFIG_LOCKDEP |
97 | static struct lockdep_map console_lock_dep_map = { | |
98 | .name = "console_lock" | |
99 | }; | |
100 | #endif | |
101 | ||
750afe7b BP |
102 | enum devkmsg_log_bits { |
103 | __DEVKMSG_LOG_BIT_ON = 0, | |
104 | __DEVKMSG_LOG_BIT_OFF, | |
105 | __DEVKMSG_LOG_BIT_LOCK, | |
106 | }; | |
107 | ||
108 | enum devkmsg_log_masks { | |
109 | DEVKMSG_LOG_MASK_ON = BIT(__DEVKMSG_LOG_BIT_ON), | |
110 | DEVKMSG_LOG_MASK_OFF = BIT(__DEVKMSG_LOG_BIT_OFF), | |
111 | DEVKMSG_LOG_MASK_LOCK = BIT(__DEVKMSG_LOG_BIT_LOCK), | |
112 | }; | |
113 | ||
114 | /* Keep both the 'on' and 'off' bits clear, i.e. ratelimit by default: */ | |
115 | #define DEVKMSG_LOG_MASK_DEFAULT 0 | |
116 | ||
117 | static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; | |
118 | ||
119 | static int __control_devkmsg(char *str) | |
120 | { | |
35c35493 CY |
121 | size_t len; |
122 | ||
750afe7b BP |
123 | if (!str) |
124 | return -EINVAL; | |
125 | ||
35c35493 CY |
126 | len = str_has_prefix(str, "on"); |
127 | if (len) { | |
750afe7b | 128 | devkmsg_log = DEVKMSG_LOG_MASK_ON; |
35c35493 CY |
129 | return len; |
130 | } | |
131 | ||
132 | len = str_has_prefix(str, "off"); | |
133 | if (len) { | |
750afe7b | 134 | devkmsg_log = DEVKMSG_LOG_MASK_OFF; |
35c35493 CY |
135 | return len; |
136 | } | |
137 | ||
138 | len = str_has_prefix(str, "ratelimit"); | |
139 | if (len) { | |
750afe7b | 140 | devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; |
35c35493 | 141 | return len; |
750afe7b | 142 | } |
35c35493 | 143 | |
750afe7b BP |
144 | return -EINVAL; |
145 | } | |
146 | ||
147 | static int __init control_devkmsg(char *str) | |
148 | { | |
149 | if (__control_devkmsg(str) < 0) | |
150 | return 1; | |
151 | ||
152 | /* | |
153 | * Set sysctl string accordingly: | |
154 | */ | |
6fd78a1a SS |
155 | if (devkmsg_log == DEVKMSG_LOG_MASK_ON) |
156 | strcpy(devkmsg_log_str, "on"); | |
157 | else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF) | |
158 | strcpy(devkmsg_log_str, "off"); | |
750afe7b BP |
159 | /* else "ratelimit" which is set by default. */ |
160 | ||
161 | /* | |
162 | * Sysctl cannot change it anymore. The kernel command line setting of | |
163 | * this parameter is to force the setting to be permanent throughout the | |
164 | * runtime of the system. This is a precation measure against userspace | |
165 | * trying to be a smarta** and attempting to change it up on us. | |
166 | */ | |
167 | devkmsg_log |= DEVKMSG_LOG_MASK_LOCK; | |
168 | ||
169 | return 0; | |
170 | } | |
171 | __setup("printk.devkmsg=", control_devkmsg); | |
172 | ||
173 | char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit"; | |
174 | ||
175 | int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, | |
32927393 | 176 | void *buffer, size_t *lenp, loff_t *ppos) |
750afe7b BP |
177 | { |
178 | char old_str[DEVKMSG_STR_MAX_SIZE]; | |
179 | unsigned int old; | |
180 | int err; | |
181 | ||
182 | if (write) { | |
183 | if (devkmsg_log & DEVKMSG_LOG_MASK_LOCK) | |
184 | return -EINVAL; | |
185 | ||
186 | old = devkmsg_log; | |
187 | strncpy(old_str, devkmsg_log_str, DEVKMSG_STR_MAX_SIZE); | |
188 | } | |
189 | ||
190 | err = proc_dostring(table, write, buffer, lenp, ppos); | |
191 | if (err) | |
192 | return err; | |
193 | ||
194 | if (write) { | |
195 | err = __control_devkmsg(devkmsg_log_str); | |
196 | ||
197 | /* | |
198 | * Do not accept an unknown string OR a known string with | |
199 | * trailing crap... | |
200 | */ | |
201 | if (err < 0 || (err + 1 != *lenp)) { | |
202 | ||
203 | /* ... and restore old setting. */ | |
204 | devkmsg_log = old; | |
205 | strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE); | |
206 | ||
207 | return -EINVAL; | |
208 | } | |
209 | } | |
210 | ||
211 | return 0; | |
212 | } | |
213 | ||
9627808d | 214 | /* Number of registered extended console drivers. */ |
6fe29354 TH |
215 | static int nr_ext_console_drivers; |
216 | ||
bd8d7cf5 JK |
217 | /* |
218 | * Helper macros to handle lockdep when locking/unlocking console_sem. We use | |
219 | * macros instead of functions so that _RET_IP_ contains useful information. | |
220 | */ | |
221 | #define down_console_sem() do { \ | |
222 | down(&console_sem);\ | |
223 | mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ | |
224 | } while (0) | |
225 | ||
226 | static int __down_trylock_console_sem(unsigned long ip) | |
227 | { | |
f975237b SS |
228 | int lock_failed; |
229 | unsigned long flags; | |
230 | ||
231 | /* | |
232 | * Here and in __up_console_sem() we need to be in safe mode, | |
233 | * because spindump/WARN/etc from under console ->lock will | |
234 | * deadlock in printk()->down_trylock_console_sem() otherwise. | |
235 | */ | |
236 | printk_safe_enter_irqsave(flags); | |
237 | lock_failed = down_trylock(&console_sem); | |
238 | printk_safe_exit_irqrestore(flags); | |
239 | ||
240 | if (lock_failed) | |
bd8d7cf5 JK |
241 | return 1; |
242 | mutex_acquire(&console_lock_dep_map, 0, 1, ip); | |
243 | return 0; | |
244 | } | |
245 | #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) | |
246 | ||
f975237b SS |
247 | static void __up_console_sem(unsigned long ip) |
248 | { | |
249 | unsigned long flags; | |
250 | ||
5facae4f | 251 | mutex_release(&console_lock_dep_map, ip); |
f975237b SS |
252 | |
253 | printk_safe_enter_irqsave(flags); | |
254 | up(&console_sem); | |
255 | printk_safe_exit_irqrestore(flags); | |
256 | } | |
257 | #define up_console_sem() __up_console_sem(_RET_IP_) | |
bd8d7cf5 | 258 | |
1da177e4 LT |
259 | /* |
260 | * This is used for debugging the mess that is the VT code by | |
261 | * keeping track if we have the console semaphore held. It's | |
262 | * definitely not the perfect debug tool (we don't know if _WE_ | |
0b90fec3 AE |
263 | * hold it and are racing, but it helps tracking those weird code |
264 | * paths in the console code where we end up in places I want | |
acebb559 | 265 | * locked without the console semaphore held). |
1da177e4 | 266 | */ |
557240b4 | 267 | static int console_locked, console_suspended; |
1da177e4 | 268 | |
fe3d8ad3 FT |
269 | /* |
270 | * If exclusive_console is non-NULL then only this console is to be printed to. | |
271 | */ | |
272 | static struct console *exclusive_console; | |
273 | ||
1da177e4 LT |
274 | /* |
275 | * Array of consoles built from command line options (console=) | |
276 | */ | |
1da177e4 LT |
277 | |
278 | #define MAX_CMDLINECONSOLES 8 | |
279 | ||
280 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
d197c43d | 281 | |
1da177e4 | 282 | static int preferred_console = -1; |
ad8cd1db | 283 | static bool has_preferred_console; |
9e124fe1 MA |
284 | int console_set_on_cmdline; |
285 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
286 | |
287 | /* Flag: console code may call schedule() */ | |
288 | static int console_may_schedule; | |
289 | ||
cca10d58 SS |
290 | enum con_msg_format_flags { |
291 | MSG_FORMAT_DEFAULT = 0, | |
292 | MSG_FORMAT_SYSLOG = (1 << 0), | |
293 | }; | |
294 | ||
295 | static int console_msg_format = MSG_FORMAT_DEFAULT; | |
296 | ||
7ff9554b | 297 | /* |
896fbe20 | 298 | * The printk log buffer consists of a sequenced collection of records, each |
74caba7f JO |
299 | * containing variable length message text. Every record also contains its |
300 | * own meta-data (@info). | |
7ff9554b | 301 | * |
896fbe20 JO |
302 | * Every record meta-data carries the timestamp in microseconds, as well as |
303 | * the standard userspace syslog level and syslog facility. The usual kernel | |
304 | * messages use LOG_KERN; userspace-injected messages always carry a matching | |
305 | * syslog facility, by default LOG_USER. The origin of every message can be | |
306 | * reliably determined that way. | |
7ff9554b | 307 | * |
896fbe20 JO |
308 | * The human readable log message of a record is available in @text, the |
309 | * length of the message text in @text_len. The stored message is not | |
310 | * terminated. | |
7ff9554b | 311 | * |
896fbe20 | 312 | * Optionally, a record can carry a dictionary of properties (key/value |
74caba7f | 313 | * pairs), to provide userspace with a machine-readable message context. |
e11fea92 KS |
314 | * |
315 | * Examples for well-defined, commonly used property names are: | |
316 | * DEVICE=b12:8 device identifier | |
317 | * b12:8 block dev_t | |
318 | * c127:3 char dev_t | |
319 | * n8 netdev ifindex | |
320 | * +sound:card0 subsystem:devname | |
321 | * SUBSYSTEM=pci driver-core subsystem name | |
322 | * | |
74caba7f JO |
323 | * Valid characters in property names are [a-zA-Z0-9.-_]. Property names |
324 | * and values are terminated by a '\0' character. | |
e11fea92 | 325 | * |
896fbe20 | 326 | * Example of record values: |
74caba7f JO |
327 | * record.text_buf = "it's a line" (unterminated) |
328 | * record.info.seq = 56 | |
329 | * record.info.ts_nsec = 36863 | |
330 | * record.info.text_len = 11 | |
331 | * record.info.facility = 0 (LOG_KERN) | |
332 | * record.info.flags = 0 | |
333 | * record.info.level = 3 (LOG_ERR) | |
334 | * record.info.caller_id = 299 (task 299) | |
335 | * record.info.dev_info.subsystem = "pci" (terminated) | |
336 | * record.info.dev_info.device = "+pci:0000:00:01.0" (terminated) | |
896fbe20 JO |
337 | * |
338 | * The 'struct printk_info' buffer must never be directly exported to | |
e11fea92 KS |
339 | * userspace, it is a kernel-private implementation detail that might |
340 | * need to be changed in the future, when the requirements change. | |
341 | * | |
342 | * /dev/kmsg exports the structured data in the following line format: | |
b389645f AO |
343 | * "<level>,<sequnum>,<timestamp>,<contflag>[,additional_values, ... ];<message text>\n" |
344 | * | |
345 | * Users of the export format should ignore possible additional values | |
346 | * separated by ',', and find the message after the ';' character. | |
e11fea92 KS |
347 | * |
348 | * The optional key/value pairs are attached as continuation lines starting | |
349 | * with a space character and terminated by a newline. All possible | |
350 | * non-prinatable characters are escaped in the "\xff" notation. | |
7ff9554b KS |
351 | */ |
352 | ||
084681d1 | 353 | enum log_flags { |
5becfb1d | 354 | LOG_NEWLINE = 2, /* text ended with a newline */ |
5becfb1d | 355 | LOG_CONT = 8, /* text is a fragment of a continuation line */ |
084681d1 KS |
356 | }; |
357 | ||
636babdc JO |
358 | /* syslog_lock protects syslog_* variables and write access to clear_seq. */ |
359 | static DEFINE_RAW_SPINLOCK(syslog_lock); | |
360 | ||
96efedf1 | 361 | #ifdef CONFIG_PRINTK |
dc72c32e | 362 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
636babdc | 363 | /* All 3 protected by @syslog_lock. */ |
7f3a781d KS |
364 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
365 | static u64 syslog_seq; | |
eb02dac9 | 366 | static size_t syslog_partial; |
e80c1a9d | 367 | static bool syslog_time; |
7ff9554b | 368 | |
996e9666 | 369 | /* All 3 protected by @console_sem. */ |
eab07260 KS |
370 | /* the next printk record to write to the console */ |
371 | static u64 console_seq; | |
f92b070f | 372 | static u64 exclusive_console_stop_seq; |
896fbe20 | 373 | static unsigned long console_dropped; |
eab07260 | 374 | |
7d7a23a9 JO |
375 | struct latched_seq { |
376 | seqcount_latch_t latch; | |
377 | u64 val[2]; | |
378 | }; | |
379 | ||
380 | /* | |
381 | * The next printk record to read after the last 'clear' command. There are | |
382 | * two copies (updated with seqcount_latch) so that reads can locklessly | |
636babdc | 383 | * access a valid value. Writers are synchronized by @syslog_lock. |
7d7a23a9 JO |
384 | */ |
385 | static struct latched_seq clear_seq = { | |
386 | .latch = SEQCNT_LATCH_ZERO(clear_seq.latch), | |
387 | .val[0] = 0, | |
388 | .val[1] = 0, | |
389 | }; | |
7ff9554b | 390 | |
15ff2069 TH |
391 | #ifdef CONFIG_PRINTK_CALLER |
392 | #define PREFIX_MAX 48 | |
393 | #else | |
70498253 | 394 | #define PREFIX_MAX 32 |
15ff2069 | 395 | #endif |
cf5b0208 JO |
396 | |
397 | /* the maximum size of a formatted record (i.e. with prefix added per line) */ | |
398 | #define CONSOLE_LOG_MAX 1024 | |
399 | ||
400 | /* the maximum size allowed to be reserved for a record */ | |
401 | #define LOG_LINE_MAX (CONSOLE_LOG_MAX - PREFIX_MAX) | |
7f3a781d | 402 | |
3824657c MK |
403 | #define LOG_LEVEL(v) ((v) & 0x07) |
404 | #define LOG_FACILITY(v) ((v) >> 3 & 0xff) | |
405 | ||
7f3a781d | 406 | /* record buffer */ |
896fbe20 | 407 | #define LOG_ALIGN __alignof__(unsigned long) |
7f3a781d | 408 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
e6fe3e5b | 409 | #define LOG_BUF_LEN_MAX (u32)(1 << 31) |
f8450fca | 410 | static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); |
7f3a781d KS |
411 | static char *log_buf = __log_buf; |
412 | static u32 log_buf_len = __LOG_BUF_LEN; | |
413 | ||
896fbe20 JO |
414 | /* |
415 | * Define the average message size. This only affects the number of | |
416 | * descriptors that will be available. Underestimating is better than | |
417 | * overestimating (too many available descriptors is better than not enough). | |
896fbe20 JO |
418 | */ |
419 | #define PRB_AVGBITS 5 /* 32 character average length */ | |
420 | ||
421 | #if CONFIG_LOG_BUF_SHIFT <= PRB_AVGBITS | |
422 | #error CONFIG_LOG_BUF_SHIFT value too small. | |
423 | #endif | |
424 | _DEFINE_PRINTKRB(printk_rb_static, CONFIG_LOG_BUF_SHIFT - PRB_AVGBITS, | |
f35efc78 | 425 | PRB_AVGBITS, &__log_buf[0]); |
896fbe20 JO |
426 | |
427 | static struct printk_ringbuffer printk_rb_dynamic; | |
428 | ||
429 | static struct printk_ringbuffer *prb = &printk_rb_static; | |
430 | ||
ab6f762f SS |
431 | /* |
432 | * We cannot access per-CPU data (e.g. per-CPU flush irq_work) before | |
433 | * per_cpu_areas are initialised. This variable is set to true when | |
434 | * it's safe to access per-CPU data. | |
435 | */ | |
436 | static bool __printk_percpu_data_ready __read_mostly; | |
437 | ||
438 | bool printk_percpu_data_ready(void) | |
439 | { | |
440 | return __printk_percpu_data_ready; | |
441 | } | |
442 | ||
636babdc | 443 | /* Must be called under syslog_lock. */ |
7d7a23a9 JO |
444 | static void latched_seq_write(struct latched_seq *ls, u64 val) |
445 | { | |
446 | raw_write_seqcount_latch(&ls->latch); | |
447 | ls->val[0] = val; | |
448 | raw_write_seqcount_latch(&ls->latch); | |
449 | ls->val[1] = val; | |
450 | } | |
451 | ||
452 | /* Can be called from any context. */ | |
453 | static u64 latched_seq_read_nolock(struct latched_seq *ls) | |
454 | { | |
455 | unsigned int seq; | |
456 | unsigned int idx; | |
457 | u64 val; | |
458 | ||
459 | do { | |
460 | seq = raw_read_seqcount_latch(&ls->latch); | |
461 | idx = seq & 0x1; | |
462 | val = ls->val[idx]; | |
463 | } while (read_seqcount_latch_retry(&ls->latch, seq)); | |
464 | ||
465 | return val; | |
466 | } | |
467 | ||
14c4000a VH |
468 | /* Return log buffer address */ |
469 | char *log_buf_addr_get(void) | |
470 | { | |
471 | return log_buf; | |
472 | } | |
473 | ||
474 | /* Return log buffer size */ | |
475 | u32 log_buf_len_get(void) | |
476 | { | |
477 | return log_buf_len; | |
478 | } | |
479 | ||
55bd53a4 PM |
480 | /* |
481 | * Define how much of the log buffer we could take at maximum. The value | |
482 | * must be greater than two. Note that only half of the buffer is available | |
483 | * when the index points to the middle. | |
484 | */ | |
485 | #define MAX_LOG_TAKE_PART 4 | |
486 | static const char trunc_msg[] = "<truncated>"; | |
487 | ||
896fbe20 | 488 | static void truncate_msg(u16 *text_len, u16 *trunc_msg_len) |
55bd53a4 PM |
489 | { |
490 | /* | |
491 | * The message should not take the whole buffer. Otherwise, it might | |
492 | * get removed too soon. | |
493 | */ | |
494 | u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART; | |
896fbe20 | 495 | |
55bd53a4 PM |
496 | if (*text_len > max_text_len) |
497 | *text_len = max_text_len; | |
896fbe20 JO |
498 | |
499 | /* enable the warning message (if there is room) */ | |
55bd53a4 | 500 | *trunc_msg_len = strlen(trunc_msg); |
896fbe20 JO |
501 | if (*text_len >= *trunc_msg_len) |
502 | *text_len -= *trunc_msg_len; | |
503 | else | |
504 | *trunc_msg_len = 0; | |
55bd53a4 PM |
505 | } |
506 | ||
e99aa461 | 507 | int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); |
637241a9 KC |
508 | |
509 | static int syslog_action_restricted(int type) | |
510 | { | |
511 | if (dmesg_restrict) | |
512 | return 1; | |
513 | /* | |
514 | * Unless restricted, we allow "read all" and "get buffer size" | |
515 | * for everybody. | |
516 | */ | |
517 | return type != SYSLOG_ACTION_READ_ALL && | |
518 | type != SYSLOG_ACTION_SIZE_BUFFER; | |
519 | } | |
520 | ||
c71b02e4 | 521 | static int check_syslog_permissions(int type, int source) |
637241a9 KC |
522 | { |
523 | /* | |
524 | * If this is from /proc/kmsg and we've already opened it, then we've | |
525 | * already done the capabilities checks at open time. | |
526 | */ | |
3ea4331c | 527 | if (source == SYSLOG_FROM_PROC && type != SYSLOG_ACTION_OPEN) |
d194e5d6 | 528 | goto ok; |
637241a9 KC |
529 | |
530 | if (syslog_action_restricted(type)) { | |
531 | if (capable(CAP_SYSLOG)) | |
d194e5d6 | 532 | goto ok; |
637241a9 KC |
533 | /* |
534 | * For historical reasons, accept CAP_SYS_ADMIN too, with | |
535 | * a warning. | |
536 | */ | |
537 | if (capable(CAP_SYS_ADMIN)) { | |
538 | pr_warn_once("%s (%d): Attempt to access syslog with " | |
539 | "CAP_SYS_ADMIN but no CAP_SYSLOG " | |
540 | "(deprecated).\n", | |
541 | current->comm, task_pid_nr(current)); | |
d194e5d6 | 542 | goto ok; |
637241a9 KC |
543 | } |
544 | return -EPERM; | |
545 | } | |
d194e5d6 | 546 | ok: |
637241a9 KC |
547 | return security_syslog(type); |
548 | } | |
549 | ||
d43ff430 TH |
550 | static void append_char(char **pp, char *e, char c) |
551 | { | |
552 | if (*pp < e) | |
553 | *(*pp)++ = c; | |
554 | } | |
637241a9 | 555 | |
896fbe20 JO |
556 | static ssize_t info_print_ext_header(char *buf, size_t size, |
557 | struct printk_info *info) | |
0a295e67 | 558 | { |
896fbe20 | 559 | u64 ts_usec = info->ts_nsec; |
15ff2069 TH |
560 | char caller[20]; |
561 | #ifdef CONFIG_PRINTK_CALLER | |
896fbe20 | 562 | u32 id = info->caller_id; |
15ff2069 TH |
563 | |
564 | snprintf(caller, sizeof(caller), ",caller=%c%u", | |
565 | id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); | |
566 | #else | |
567 | caller[0] = '\0'; | |
568 | #endif | |
0a295e67 TH |
569 | |
570 | do_div(ts_usec, 1000); | |
571 | ||
15ff2069 | 572 | return scnprintf(buf, size, "%u,%llu,%llu,%c%s;", |
896fbe20 JO |
573 | (info->facility << 3) | info->level, info->seq, |
574 | ts_usec, info->flags & LOG_CONT ? 'c' : '-', caller); | |
0a295e67 TH |
575 | } |
576 | ||
74caba7f JO |
577 | static ssize_t msg_add_ext_text(char *buf, size_t size, |
578 | const char *text, size_t text_len, | |
579 | unsigned char endc) | |
0a295e67 TH |
580 | { |
581 | char *p = buf, *e = buf + size; | |
582 | size_t i; | |
583 | ||
584 | /* escape non-printable characters */ | |
585 | for (i = 0; i < text_len; i++) { | |
586 | unsigned char c = text[i]; | |
587 | ||
588 | if (c < ' ' || c >= 127 || c == '\\') | |
589 | p += scnprintf(p, e - p, "\\x%02x", c); | |
590 | else | |
591 | append_char(&p, e, c); | |
592 | } | |
74caba7f | 593 | append_char(&p, e, endc); |
0a295e67 | 594 | |
74caba7f JO |
595 | return p - buf; |
596 | } | |
0a295e67 | 597 | |
74caba7f JO |
598 | static ssize_t msg_add_dict_text(char *buf, size_t size, |
599 | const char *key, const char *val) | |
600 | { | |
601 | size_t val_len = strlen(val); | |
602 | ssize_t len; | |
0a295e67 | 603 | |
74caba7f JO |
604 | if (!val_len) |
605 | return 0; | |
0a295e67 | 606 | |
74caba7f JO |
607 | len = msg_add_ext_text(buf, size, "", 0, ' '); /* dict prefix */ |
608 | len += msg_add_ext_text(buf + len, size - len, key, strlen(key), '='); | |
609 | len += msg_add_ext_text(buf + len, size - len, val, val_len, '\n'); | |
0a295e67 | 610 | |
74caba7f JO |
611 | return len; |
612 | } | |
0a295e67 | 613 | |
74caba7f JO |
614 | static ssize_t msg_print_ext_body(char *buf, size_t size, |
615 | char *text, size_t text_len, | |
616 | struct dev_printk_info *dev_info) | |
617 | { | |
618 | ssize_t len; | |
0a295e67 | 619 | |
74caba7f JO |
620 | len = msg_add_ext_text(buf, size, text, text_len, '\n'); |
621 | ||
622 | if (!dev_info) | |
623 | goto out; | |
624 | ||
625 | len += msg_add_dict_text(buf + len, size - len, "SUBSYSTEM", | |
626 | dev_info->subsystem); | |
627 | len += msg_add_dict_text(buf + len, size - len, "DEVICE", | |
628 | dev_info->device); | |
629 | out: | |
630 | return len; | |
0a295e67 TH |
631 | } |
632 | ||
e11fea92 KS |
633 | /* /dev/kmsg - userspace message inject/listen interface */ |
634 | struct devkmsg_user { | |
35b2b163 | 635 | atomic64_t seq; |
750afe7b | 636 | struct ratelimit_state rs; |
e11fea92 | 637 | struct mutex lock; |
d43ff430 | 638 | char buf[CONSOLE_EXT_LOG_MAX]; |
896fbe20 JO |
639 | |
640 | struct printk_info info; | |
641 | char text_buf[CONSOLE_EXT_LOG_MAX]; | |
896fbe20 | 642 | struct printk_record record; |
e11fea92 KS |
643 | }; |
644 | ||
9adcfaff TH |
645 | static __printf(3, 4) __cold |
646 | int devkmsg_emit(int facility, int level, const char *fmt, ...) | |
647 | { | |
648 | va_list args; | |
649 | int r; | |
650 | ||
651 | va_start(args, fmt); | |
74caba7f | 652 | r = vprintk_emit(facility, level, NULL, fmt, args); |
9adcfaff TH |
653 | va_end(args); |
654 | ||
655 | return r; | |
656 | } | |
657 | ||
849f3127 | 658 | static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from) |
e11fea92 KS |
659 | { |
660 | char *buf, *line; | |
e11fea92 KS |
661 | int level = default_message_loglevel; |
662 | int facility = 1; /* LOG_USER */ | |
750afe7b BP |
663 | struct file *file = iocb->ki_filp; |
664 | struct devkmsg_user *user = file->private_data; | |
66ee59af | 665 | size_t len = iov_iter_count(from); |
e11fea92 KS |
666 | ssize_t ret = len; |
667 | ||
750afe7b | 668 | if (!user || len > LOG_LINE_MAX) |
e11fea92 | 669 | return -EINVAL; |
750afe7b BP |
670 | |
671 | /* Ignore when user logging is disabled. */ | |
672 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) | |
673 | return len; | |
674 | ||
675 | /* Ratelimit when not explicitly enabled. */ | |
676 | if (!(devkmsg_log & DEVKMSG_LOG_MASK_ON)) { | |
677 | if (!___ratelimit(&user->rs, current->comm)) | |
678 | return ret; | |
679 | } | |
680 | ||
e11fea92 KS |
681 | buf = kmalloc(len+1, GFP_KERNEL); |
682 | if (buf == NULL) | |
683 | return -ENOMEM; | |
684 | ||
849f3127 | 685 | buf[len] = '\0'; |
cbbd26b8 | 686 | if (!copy_from_iter_full(buf, len, from)) { |
849f3127 AV |
687 | kfree(buf); |
688 | return -EFAULT; | |
e11fea92 KS |
689 | } |
690 | ||
691 | /* | |
692 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace | |
693 | * the decimal value represents 32bit, the lower 3 bit are the log | |
694 | * level, the rest are the log facility. | |
695 | * | |
696 | * If no prefix or no userspace facility is specified, we | |
697 | * enforce LOG_USER, to be able to reliably distinguish | |
698 | * kernel-generated messages from userspace-injected ones. | |
699 | */ | |
700 | line = buf; | |
701 | if (line[0] == '<') { | |
702 | char *endp = NULL; | |
3824657c | 703 | unsigned int u; |
e11fea92 | 704 | |
3824657c | 705 | u = simple_strtoul(line + 1, &endp, 10); |
e11fea92 | 706 | if (endp && endp[0] == '>') { |
3824657c MK |
707 | level = LOG_LEVEL(u); |
708 | if (LOG_FACILITY(u) != 0) | |
709 | facility = LOG_FACILITY(u); | |
e11fea92 | 710 | endp++; |
e11fea92 KS |
711 | line = endp; |
712 | } | |
713 | } | |
e11fea92 | 714 | |
9adcfaff | 715 | devkmsg_emit(facility, level, "%s", line); |
e11fea92 KS |
716 | kfree(buf); |
717 | return ret; | |
718 | } | |
719 | ||
720 | static ssize_t devkmsg_read(struct file *file, char __user *buf, | |
721 | size_t count, loff_t *ppos) | |
722 | { | |
723 | struct devkmsg_user *user = file->private_data; | |
896fbe20 | 724 | struct printk_record *r = &user->record; |
e11fea92 KS |
725 | size_t len; |
726 | ssize_t ret; | |
727 | ||
728 | if (!user) | |
729 | return -EBADF; | |
730 | ||
4a77a5a0 YL |
731 | ret = mutex_lock_interruptible(&user->lock); |
732 | if (ret) | |
733 | return ret; | |
de6fcbdb | 734 | |
996e9666 | 735 | printk_safe_enter_irq(); |
35b2b163 | 736 | if (!prb_read_valid(prb, atomic64_read(&user->seq), r)) { |
e11fea92 KS |
737 | if (file->f_flags & O_NONBLOCK) { |
738 | ret = -EAGAIN; | |
996e9666 | 739 | printk_safe_exit_irq(); |
e11fea92 KS |
740 | goto out; |
741 | } | |
742 | ||
996e9666 | 743 | printk_safe_exit_irq(); |
e11fea92 | 744 | ret = wait_event_interruptible(log_wait, |
35b2b163 | 745 | prb_read_valid(prb, atomic64_read(&user->seq), r)); |
e11fea92 KS |
746 | if (ret) |
747 | goto out; | |
996e9666 | 748 | printk_safe_enter_irq(); |
e11fea92 KS |
749 | } |
750 | ||
35b2b163 | 751 | if (r->info->seq != atomic64_read(&user->seq)) { |
e11fea92 | 752 | /* our last seen message is gone, return error and reset */ |
35b2b163 | 753 | atomic64_set(&user->seq, r->info->seq); |
e11fea92 | 754 | ret = -EPIPE; |
996e9666 | 755 | printk_safe_exit_irq(); |
e11fea92 KS |
756 | goto out; |
757 | } | |
758 | ||
896fbe20 | 759 | len = info_print_ext_header(user->buf, sizeof(user->buf), r->info); |
0a295e67 | 760 | len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len, |
74caba7f JO |
761 | &r->text_buf[0], r->info->text_len, |
762 | &r->info->dev_info); | |
d39f3d77 | 763 | |
35b2b163 | 764 | atomic64_set(&user->seq, r->info->seq + 1); |
996e9666 | 765 | printk_safe_exit_irq(); |
e11fea92 KS |
766 | |
767 | if (len > count) { | |
768 | ret = -EINVAL; | |
769 | goto out; | |
770 | } | |
771 | ||
772 | if (copy_to_user(buf, user->buf, len)) { | |
773 | ret = -EFAULT; | |
774 | goto out; | |
775 | } | |
776 | ret = len; | |
777 | out: | |
778 | mutex_unlock(&user->lock); | |
779 | return ret; | |
780 | } | |
781 | ||
bc885f1a BM |
782 | /* |
783 | * Be careful when modifying this function!!! | |
784 | * | |
785 | * Only few operations are supported because the device works only with the | |
786 | * entire variable length messages (records). Non-standard values are | |
787 | * returned in the other cases and has been this way for quite some time. | |
788 | * User space applications might depend on this behavior. | |
789 | */ | |
e11fea92 KS |
790 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) |
791 | { | |
792 | struct devkmsg_user *user = file->private_data; | |
793 | loff_t ret = 0; | |
794 | ||
795 | if (!user) | |
796 | return -EBADF; | |
797 | if (offset) | |
798 | return -ESPIPE; | |
799 | ||
996e9666 | 800 | printk_safe_enter_irq(); |
e11fea92 KS |
801 | switch (whence) { |
802 | case SEEK_SET: | |
803 | /* the first record */ | |
35b2b163 | 804 | atomic64_set(&user->seq, prb_first_valid_seq(prb)); |
e11fea92 KS |
805 | break; |
806 | case SEEK_DATA: | |
807 | /* | |
808 | * The first record after the last SYSLOG_ACTION_CLEAR, | |
809 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself | |
810 | * changes no global state, and does not clear anything. | |
811 | */ | |
35b2b163 | 812 | atomic64_set(&user->seq, latched_seq_read_nolock(&clear_seq)); |
e11fea92 KS |
813 | break; |
814 | case SEEK_END: | |
815 | /* after the last record */ | |
35b2b163 | 816 | atomic64_set(&user->seq, prb_next_seq(prb)); |
e11fea92 KS |
817 | break; |
818 | default: | |
819 | ret = -EINVAL; | |
820 | } | |
996e9666 | 821 | printk_safe_exit_irq(); |
e11fea92 KS |
822 | return ret; |
823 | } | |
824 | ||
9dd95748 | 825 | static __poll_t devkmsg_poll(struct file *file, poll_table *wait) |
e11fea92 KS |
826 | { |
827 | struct devkmsg_user *user = file->private_data; | |
13791c80 | 828 | struct printk_info info; |
9dd95748 | 829 | __poll_t ret = 0; |
e11fea92 KS |
830 | |
831 | if (!user) | |
a9a08845 | 832 | return EPOLLERR|EPOLLNVAL; |
e11fea92 KS |
833 | |
834 | poll_wait(file, &log_wait, wait); | |
835 | ||
996e9666 | 836 | printk_safe_enter_irq(); |
35b2b163 | 837 | if (prb_read_valid_info(prb, atomic64_read(&user->seq), &info, NULL)) { |
e11fea92 | 838 | /* return error when data has vanished underneath us */ |
35b2b163 | 839 | if (info.seq != atomic64_read(&user->seq)) |
a9a08845 | 840 | ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI; |
0a285317 | 841 | else |
a9a08845 | 842 | ret = EPOLLIN|EPOLLRDNORM; |
e11fea92 | 843 | } |
996e9666 | 844 | printk_safe_exit_irq(); |
e11fea92 KS |
845 | |
846 | return ret; | |
847 | } | |
848 | ||
849 | static int devkmsg_open(struct inode *inode, struct file *file) | |
850 | { | |
851 | struct devkmsg_user *user; | |
852 | int err; | |
853 | ||
750afe7b BP |
854 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) |
855 | return -EPERM; | |
e11fea92 | 856 | |
750afe7b BP |
857 | /* write-only does not need any file context */ |
858 | if ((file->f_flags & O_ACCMODE) != O_WRONLY) { | |
859 | err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, | |
860 | SYSLOG_FROM_READER); | |
861 | if (err) | |
862 | return err; | |
863 | } | |
e11fea92 KS |
864 | |
865 | user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); | |
866 | if (!user) | |
867 | return -ENOMEM; | |
868 | ||
750afe7b BP |
869 | ratelimit_default_init(&user->rs); |
870 | ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE); | |
871 | ||
e11fea92 KS |
872 | mutex_init(&user->lock); |
873 | ||
896fbe20 | 874 | prb_rec_init_rd(&user->record, &user->info, |
f35efc78 | 875 | &user->text_buf[0], sizeof(user->text_buf)); |
896fbe20 | 876 | |
996e9666 | 877 | printk_safe_enter_irq(); |
35b2b163 | 878 | atomic64_set(&user->seq, prb_first_valid_seq(prb)); |
996e9666 | 879 | printk_safe_exit_irq(); |
e11fea92 KS |
880 | |
881 | file->private_data = user; | |
882 | return 0; | |
883 | } | |
884 | ||
885 | static int devkmsg_release(struct inode *inode, struct file *file) | |
886 | { | |
887 | struct devkmsg_user *user = file->private_data; | |
888 | ||
889 | if (!user) | |
890 | return 0; | |
891 | ||
750afe7b BP |
892 | ratelimit_state_exit(&user->rs); |
893 | ||
e11fea92 KS |
894 | mutex_destroy(&user->lock); |
895 | kfree(user); | |
896 | return 0; | |
897 | } | |
898 | ||
899 | const struct file_operations kmsg_fops = { | |
900 | .open = devkmsg_open, | |
901 | .read = devkmsg_read, | |
849f3127 | 902 | .write_iter = devkmsg_write, |
e11fea92 KS |
903 | .llseek = devkmsg_llseek, |
904 | .poll = devkmsg_poll, | |
905 | .release = devkmsg_release, | |
906 | }; | |
907 | ||
692f66f2 | 908 | #ifdef CONFIG_CRASH_CORE |
04d491ab | 909 | /* |
4c1ace64 | 910 | * This appends the listed symbols to /proc/vmcore |
04d491ab | 911 | * |
4c1ace64 | 912 | * /proc/vmcore is used by various utilities, like crash and makedumpfile to |
04d491ab NH |
913 | * obtain access to symbols that are otherwise very difficult to locate. These |
914 | * symbols are specifically used so that utilities can access and extract the | |
915 | * dmesg log from a vmcore file after a crash. | |
916 | */ | |
692f66f2 | 917 | void log_buf_vmcoreinfo_setup(void) |
04d491ab | 918 | { |
74caba7f JO |
919 | struct dev_printk_info *dev_info = NULL; |
920 | ||
896fbe20 JO |
921 | VMCOREINFO_SYMBOL(prb); |
922 | VMCOREINFO_SYMBOL(printk_rb_static); | |
923 | VMCOREINFO_SYMBOL(clear_seq); | |
924 | ||
6791457a | 925 | /* |
896fbe20 | 926 | * Export struct size and field offsets. User space tools can |
6791457a VG |
927 | * parse it and detect any changes to structure down the line. |
928 | */ | |
896fbe20 JO |
929 | |
930 | VMCOREINFO_STRUCT_SIZE(printk_ringbuffer); | |
931 | VMCOREINFO_OFFSET(printk_ringbuffer, desc_ring); | |
932 | VMCOREINFO_OFFSET(printk_ringbuffer, text_data_ring); | |
896fbe20 JO |
933 | VMCOREINFO_OFFSET(printk_ringbuffer, fail); |
934 | ||
935 | VMCOREINFO_STRUCT_SIZE(prb_desc_ring); | |
936 | VMCOREINFO_OFFSET(prb_desc_ring, count_bits); | |
937 | VMCOREINFO_OFFSET(prb_desc_ring, descs); | |
cfe2790b | 938 | VMCOREINFO_OFFSET(prb_desc_ring, infos); |
896fbe20 JO |
939 | VMCOREINFO_OFFSET(prb_desc_ring, head_id); |
940 | VMCOREINFO_OFFSET(prb_desc_ring, tail_id); | |
941 | ||
942 | VMCOREINFO_STRUCT_SIZE(prb_desc); | |
896fbe20 JO |
943 | VMCOREINFO_OFFSET(prb_desc, state_var); |
944 | VMCOREINFO_OFFSET(prb_desc, text_blk_lpos); | |
896fbe20 JO |
945 | |
946 | VMCOREINFO_STRUCT_SIZE(prb_data_blk_lpos); | |
947 | VMCOREINFO_OFFSET(prb_data_blk_lpos, begin); | |
948 | VMCOREINFO_OFFSET(prb_data_blk_lpos, next); | |
949 | ||
950 | VMCOREINFO_STRUCT_SIZE(printk_info); | |
951 | VMCOREINFO_OFFSET(printk_info, seq); | |
952 | VMCOREINFO_OFFSET(printk_info, ts_nsec); | |
953 | VMCOREINFO_OFFSET(printk_info, text_len); | |
896fbe20 | 954 | VMCOREINFO_OFFSET(printk_info, caller_id); |
74caba7f JO |
955 | VMCOREINFO_OFFSET(printk_info, dev_info); |
956 | ||
957 | VMCOREINFO_STRUCT_SIZE(dev_printk_info); | |
958 | VMCOREINFO_OFFSET(dev_printk_info, subsystem); | |
959 | VMCOREINFO_LENGTH(printk_info_subsystem, sizeof(dev_info->subsystem)); | |
960 | VMCOREINFO_OFFSET(dev_printk_info, device); | |
961 | VMCOREINFO_LENGTH(printk_info_device, sizeof(dev_info->device)); | |
896fbe20 JO |
962 | |
963 | VMCOREINFO_STRUCT_SIZE(prb_data_ring); | |
964 | VMCOREINFO_OFFSET(prb_data_ring, size_bits); | |
965 | VMCOREINFO_OFFSET(prb_data_ring, data); | |
966 | VMCOREINFO_OFFSET(prb_data_ring, head_lpos); | |
967 | VMCOREINFO_OFFSET(prb_data_ring, tail_lpos); | |
968 | ||
969 | VMCOREINFO_SIZE(atomic_long_t); | |
970 | VMCOREINFO_TYPE_OFFSET(atomic_long_t, counter); | |
7d7a23a9 JO |
971 | |
972 | VMCOREINFO_STRUCT_SIZE(latched_seq); | |
973 | VMCOREINFO_OFFSET(latched_seq, val); | |
04d491ab NH |
974 | } |
975 | #endif | |
976 | ||
162a7e75 MT |
977 | /* requested log_buf_len from kernel cmdline */ |
978 | static unsigned long __initdata new_log_buf_len; | |
979 | ||
c0a318a3 | 980 | /* we practice scaling the ring buffer by powers of 2 */ |
e6fe3e5b | 981 | static void __init log_buf_len_update(u64 size) |
1da177e4 | 982 | { |
e6fe3e5b HZ |
983 | if (size > (u64)LOG_BUF_LEN_MAX) { |
984 | size = (u64)LOG_BUF_LEN_MAX; | |
985 | pr_err("log_buf over 2G is not supported.\n"); | |
986 | } | |
987 | ||
1da177e4 LT |
988 | if (size) |
989 | size = roundup_pow_of_two(size); | |
162a7e75 | 990 | if (size > log_buf_len) |
e6fe3e5b | 991 | new_log_buf_len = (unsigned long)size; |
c0a318a3 LR |
992 | } |
993 | ||
994 | /* save requested log_buf_len since it's too early to process it */ | |
995 | static int __init log_buf_len_setup(char *str) | |
996 | { | |
e6fe3e5b | 997 | u64 size; |
277fcdb2 HZ |
998 | |
999 | if (!str) | |
1000 | return -EINVAL; | |
1001 | ||
1002 | size = memparse(str, &str); | |
c0a318a3 LR |
1003 | |
1004 | log_buf_len_update(size); | |
162a7e75 MT |
1005 | |
1006 | return 0; | |
1da177e4 | 1007 | } |
162a7e75 MT |
1008 | early_param("log_buf_len", log_buf_len_setup); |
1009 | ||
2240a31d GU |
1010 | #ifdef CONFIG_SMP |
1011 | #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) | |
1012 | ||
23b2899f LR |
1013 | static void __init log_buf_add_cpu(void) |
1014 | { | |
1015 | unsigned int cpu_extra; | |
1016 | ||
1017 | /* | |
1018 | * archs should set up cpu_possible_bits properly with | |
1019 | * set_cpu_possible() after setup_arch() but just in | |
1020 | * case lets ensure this is valid. | |
1021 | */ | |
1022 | if (num_possible_cpus() == 1) | |
1023 | return; | |
1024 | ||
1025 | cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; | |
1026 | ||
1027 | /* by default this will only continue through for large > 64 CPUs */ | |
1028 | if (cpu_extra <= __LOG_BUF_LEN / 2) | |
1029 | return; | |
1030 | ||
1031 | pr_info("log_buf_len individual max cpu contribution: %d bytes\n", | |
1032 | __LOG_CPU_MAX_BUF_LEN); | |
1033 | pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", | |
1034 | cpu_extra); | |
1035 | pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); | |
1036 | ||
1037 | log_buf_len_update(cpu_extra + __LOG_BUF_LEN); | |
1038 | } | |
2240a31d GU |
1039 | #else /* !CONFIG_SMP */ |
1040 | static inline void log_buf_add_cpu(void) {} | |
1041 | #endif /* CONFIG_SMP */ | |
23b2899f | 1042 | |
ab6f762f SS |
1043 | static void __init set_percpu_data_ready(void) |
1044 | { | |
1045 | printk_safe_init(); | |
1046 | /* Make sure we set this flag only after printk_safe() init is done */ | |
1047 | barrier(); | |
1048 | __printk_percpu_data_ready = true; | |
1049 | } | |
1050 | ||
896fbe20 JO |
1051 | static unsigned int __init add_to_rb(struct printk_ringbuffer *rb, |
1052 | struct printk_record *r) | |
1053 | { | |
1054 | struct prb_reserved_entry e; | |
1055 | struct printk_record dest_r; | |
1056 | ||
f35efc78 | 1057 | prb_rec_init_wr(&dest_r, r->info->text_len); |
896fbe20 JO |
1058 | |
1059 | if (!prb_reserve(&e, rb, &dest_r)) | |
1060 | return 0; | |
1061 | ||
cc5c7041 JO |
1062 | memcpy(&dest_r.text_buf[0], &r->text_buf[0], r->info->text_len); |
1063 | dest_r.info->text_len = r->info->text_len; | |
896fbe20 JO |
1064 | dest_r.info->facility = r->info->facility; |
1065 | dest_r.info->level = r->info->level; | |
1066 | dest_r.info->flags = r->info->flags; | |
1067 | dest_r.info->ts_nsec = r->info->ts_nsec; | |
1068 | dest_r.info->caller_id = r->info->caller_id; | |
74caba7f | 1069 | memcpy(&dest_r.info->dev_info, &r->info->dev_info, sizeof(dest_r.info->dev_info)); |
896fbe20 | 1070 | |
f5f022e5 | 1071 | prb_final_commit(&e); |
896fbe20 JO |
1072 | |
1073 | return prb_record_text_space(&e); | |
1074 | } | |
1075 | ||
0463d04e | 1076 | static char setup_text_buf[LOG_LINE_MAX] __initdata; |
896fbe20 | 1077 | |
162a7e75 MT |
1078 | void __init setup_log_buf(int early) |
1079 | { | |
cfe2790b | 1080 | struct printk_info *new_infos; |
896fbe20 JO |
1081 | unsigned int new_descs_count; |
1082 | struct prb_desc *new_descs; | |
1083 | struct printk_info info; | |
1084 | struct printk_record r; | |
1085 | size_t new_descs_size; | |
cfe2790b | 1086 | size_t new_infos_size; |
162a7e75 | 1087 | unsigned long flags; |
162a7e75 | 1088 | char *new_log_buf; |
d2130e82 | 1089 | unsigned int free; |
896fbe20 | 1090 | u64 seq; |
162a7e75 | 1091 | |
ab6f762f SS |
1092 | /* |
1093 | * Some archs call setup_log_buf() multiple times - first is very | |
1094 | * early, e.g. from setup_arch(), and second - when percpu_areas | |
1095 | * are initialised. | |
1096 | */ | |
1097 | if (!early) | |
1098 | set_percpu_data_ready(); | |
1099 | ||
23b2899f LR |
1100 | if (log_buf != __log_buf) |
1101 | return; | |
1102 | ||
1103 | if (!early && !new_log_buf_len) | |
1104 | log_buf_add_cpu(); | |
1105 | ||
162a7e75 MT |
1106 | if (!new_log_buf_len) |
1107 | return; | |
1da177e4 | 1108 | |
896fbe20 JO |
1109 | new_descs_count = new_log_buf_len >> PRB_AVGBITS; |
1110 | if (new_descs_count == 0) { | |
1111 | pr_err("new_log_buf_len: %lu too small\n", new_log_buf_len); | |
1112 | return; | |
1113 | } | |
1114 | ||
26fb3dae | 1115 | new_log_buf = memblock_alloc(new_log_buf_len, LOG_ALIGN); |
162a7e75 | 1116 | if (unlikely(!new_log_buf)) { |
896fbe20 JO |
1117 | pr_err("log_buf_len: %lu text bytes not available\n", |
1118 | new_log_buf_len); | |
162a7e75 MT |
1119 | return; |
1120 | } | |
1121 | ||
896fbe20 JO |
1122 | new_descs_size = new_descs_count * sizeof(struct prb_desc); |
1123 | new_descs = memblock_alloc(new_descs_size, LOG_ALIGN); | |
1124 | if (unlikely(!new_descs)) { | |
1125 | pr_err("log_buf_len: %zu desc bytes not available\n", | |
1126 | new_descs_size); | |
f35efc78 | 1127 | goto err_free_log_buf; |
cfe2790b JO |
1128 | } |
1129 | ||
1130 | new_infos_size = new_descs_count * sizeof(struct printk_info); | |
1131 | new_infos = memblock_alloc(new_infos_size, LOG_ALIGN); | |
1132 | if (unlikely(!new_infos)) { | |
1133 | pr_err("log_buf_len: %zu info bytes not available\n", | |
1134 | new_infos_size); | |
1135 | goto err_free_descs; | |
896fbe20 JO |
1136 | } |
1137 | ||
f35efc78 | 1138 | prb_rec_init_rd(&r, &info, &setup_text_buf[0], sizeof(setup_text_buf)); |
896fbe20 JO |
1139 | |
1140 | prb_init(&printk_rb_dynamic, | |
1141 | new_log_buf, ilog2(new_log_buf_len), | |
cfe2790b JO |
1142 | new_descs, ilog2(new_descs_count), |
1143 | new_infos); | |
896fbe20 | 1144 | |
b031a684 | 1145 | printk_safe_enter_irqsave(flags); |
896fbe20 | 1146 | |
162a7e75 MT |
1147 | log_buf_len = new_log_buf_len; |
1148 | log_buf = new_log_buf; | |
1149 | new_log_buf_len = 0; | |
896fbe20 JO |
1150 | |
1151 | free = __LOG_BUF_LEN; | |
1152 | prb_for_each_record(0, &printk_rb_static, seq, &r) | |
1153 | free -= add_to_rb(&printk_rb_dynamic, &r); | |
1154 | ||
1155 | /* | |
1156 | * This is early enough that everything is still running on the | |
1157 | * boot CPU and interrupts are disabled. So no new messages will | |
1158 | * appear during the transition to the dynamic buffer. | |
1159 | */ | |
1160 | prb = &printk_rb_dynamic; | |
1161 | ||
b031a684 | 1162 | printk_safe_exit_irqrestore(flags); |
162a7e75 | 1163 | |
896fbe20 JO |
1164 | if (seq != prb_next_seq(&printk_rb_static)) { |
1165 | pr_err("dropped %llu messages\n", | |
1166 | prb_next_seq(&printk_rb_static) - seq); | |
1167 | } | |
1168 | ||
e6fe3e5b HZ |
1169 | pr_info("log_buf_len: %u bytes\n", log_buf_len); |
1170 | pr_info("early log buf free: %u(%u%%)\n", | |
162a7e75 | 1171 | free, (free * 100) / __LOG_BUF_LEN); |
cfe2790b JO |
1172 | return; |
1173 | ||
1174 | err_free_descs: | |
1175 | memblock_free(__pa(new_descs), new_descs_size); | |
cfe2790b JO |
1176 | err_free_log_buf: |
1177 | memblock_free(__pa(new_log_buf), new_log_buf_len); | |
162a7e75 | 1178 | } |
1da177e4 | 1179 | |
2fa72c8f AC |
1180 | static bool __read_mostly ignore_loglevel; |
1181 | ||
1182 | static int __init ignore_loglevel_setup(char *str) | |
1183 | { | |
d25d9fec | 1184 | ignore_loglevel = true; |
27083bac | 1185 | pr_info("debug: ignoring loglevel setting.\n"); |
2fa72c8f AC |
1186 | |
1187 | return 0; | |
1188 | } | |
1189 | ||
1190 | early_param("ignore_loglevel", ignore_loglevel_setup); | |
1191 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); | |
205bd3d2 JP |
1192 | MODULE_PARM_DESC(ignore_loglevel, |
1193 | "ignore loglevel setting (prints all kernel messages to the console)"); | |
2fa72c8f | 1194 | |
cf775444 SS |
1195 | static bool suppress_message_printing(int level) |
1196 | { | |
1197 | return (level >= console_loglevel && !ignore_loglevel); | |
1198 | } | |
1199 | ||
bfe8df3d RD |
1200 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
1201 | ||
674dff65 | 1202 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 1203 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
1204 | |
1205 | static int __init boot_delay_setup(char *str) | |
1206 | { | |
1207 | unsigned long lpj; | |
bfe8df3d RD |
1208 | |
1209 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
1210 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
1211 | ||
1212 | get_option(&str, &boot_delay); | |
1213 | if (boot_delay > 10 * 1000) | |
1214 | boot_delay = 0; | |
1215 | ||
3a3b6ed2 DY |
1216 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
1217 | "HZ: %d, loops_per_msec: %llu\n", | |
1218 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
29e9d225 | 1219 | return 0; |
bfe8df3d | 1220 | } |
29e9d225 | 1221 | early_param("boot_delay", boot_delay_setup); |
bfe8df3d | 1222 | |
2fa72c8f | 1223 | static void boot_delay_msec(int level) |
bfe8df3d RD |
1224 | { |
1225 | unsigned long long k; | |
1226 | unsigned long timeout; | |
1227 | ||
ff48cd26 | 1228 | if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING) |
cf775444 | 1229 | || suppress_message_printing(level)) { |
bfe8df3d | 1230 | return; |
2fa72c8f | 1231 | } |
bfe8df3d | 1232 | |
3a3b6ed2 | 1233 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
1234 | |
1235 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
1236 | while (k) { | |
1237 | k--; | |
1238 | cpu_relax(); | |
1239 | /* | |
1240 | * use (volatile) jiffies to prevent | |
1241 | * compiler reduction; loop termination via jiffies | |
1242 | * is secondary and may or may not happen. | |
1243 | */ | |
1244 | if (time_after(jiffies, timeout)) | |
1245 | break; | |
1246 | touch_nmi_watchdog(); | |
1247 | } | |
1248 | } | |
1249 | #else | |
2fa72c8f | 1250 | static inline void boot_delay_msec(int level) |
bfe8df3d RD |
1251 | { |
1252 | } | |
1253 | #endif | |
1254 | ||
e99aa461 | 1255 | static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); |
7ff9554b KS |
1256 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1257 | ||
07c17732 | 1258 | static size_t print_syslog(unsigned int level, char *buf) |
084681d1 | 1259 | { |
07c17732 TH |
1260 | return sprintf(buf, "<%u>", level); |
1261 | } | |
35dac27c | 1262 | |
084681d1 KS |
1263 | static size_t print_time(u64 ts, char *buf) |
1264 | { | |
e80c1a9d | 1265 | unsigned long rem_nsec = do_div(ts, 1000000000); |
084681d1 | 1266 | |
15ff2069 | 1267 | return sprintf(buf, "[%5lu.%06lu]", |
084681d1 KS |
1268 | (unsigned long)ts, rem_nsec / 1000); |
1269 | } | |
1270 | ||
15ff2069 TH |
1271 | #ifdef CONFIG_PRINTK_CALLER |
1272 | static size_t print_caller(u32 id, char *buf) | |
1273 | { | |
1274 | char caller[12]; | |
1275 | ||
1276 | snprintf(caller, sizeof(caller), "%c%u", | |
1277 | id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); | |
1278 | return sprintf(buf, "[%6s]", caller); | |
1279 | } | |
1280 | #else | |
1281 | #define print_caller(id, buf) 0 | |
1282 | #endif | |
1283 | ||
896fbe20 JO |
1284 | static size_t info_print_prefix(const struct printk_info *info, bool syslog, |
1285 | bool time, char *buf) | |
649e6ee3 | 1286 | { |
3ce9a7c0 | 1287 | size_t len = 0; |
649e6ee3 | 1288 | |
07c17732 | 1289 | if (syslog) |
896fbe20 | 1290 | len = print_syslog((info->facility << 3) | info->level, buf); |
15ff2069 | 1291 | |
e80c1a9d | 1292 | if (time) |
896fbe20 | 1293 | len += print_time(info->ts_nsec, buf + len); |
15ff2069 | 1294 | |
896fbe20 | 1295 | len += print_caller(info->caller_id, buf + len); |
15ff2069 TH |
1296 | |
1297 | if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) { | |
1298 | buf[len++] = ' '; | |
1299 | buf[len] = '\0'; | |
1300 | } | |
1301 | ||
3ce9a7c0 | 1302 | return len; |
649e6ee3 KS |
1303 | } |
1304 | ||
896fbe20 JO |
1305 | /* |
1306 | * Prepare the record for printing. The text is shifted within the given | |
1307 | * buffer to avoid a need for another one. The following operations are | |
1308 | * done: | |
1309 | * | |
1310 | * - Add prefix for each line. | |
f0e386ee | 1311 | * - Drop truncated lines that no longer fit into the buffer. |
896fbe20 | 1312 | * - Add the trailing newline that has been removed in vprintk_store(). |
f0e386ee JO |
1313 | * - Add a string terminator. |
1314 | * | |
1315 | * Since the produced string is always terminated, the maximum possible | |
1316 | * return value is @r->text_buf_size - 1; | |
896fbe20 JO |
1317 | * |
1318 | * Return: The length of the updated/prepared text, including the added | |
f0e386ee JO |
1319 | * prefixes and the newline. The terminator is not counted. The dropped |
1320 | * line(s) are not counted. | |
896fbe20 JO |
1321 | */ |
1322 | static size_t record_print_text(struct printk_record *r, bool syslog, | |
1323 | bool time) | |
7ff9554b | 1324 | { |
896fbe20 JO |
1325 | size_t text_len = r->info->text_len; |
1326 | size_t buf_size = r->text_buf_size; | |
1327 | char *text = r->text_buf; | |
07c17732 | 1328 | char prefix[PREFIX_MAX]; |
896fbe20 JO |
1329 | bool truncated = false; |
1330 | size_t prefix_len; | |
1331 | size_t line_len; | |
1332 | size_t len = 0; | |
1333 | char *next; | |
3ce9a7c0 | 1334 | |
59f8bcca JO |
1335 | /* |
1336 | * If the message was truncated because the buffer was not large | |
1337 | * enough, treat the available text as if it were the full text. | |
1338 | */ | |
1339 | if (text_len > buf_size) | |
1340 | text_len = buf_size; | |
3ce9a7c0 | 1341 | |
896fbe20 | 1342 | prefix_len = info_print_prefix(r->info, syslog, time, prefix); |
3ce9a7c0 | 1343 | |
896fbe20 JO |
1344 | /* |
1345 | * @text_len: bytes of unprocessed text | |
1346 | * @line_len: bytes of current line _without_ newline | |
1347 | * @text: pointer to beginning of current line | |
1348 | * @len: number of bytes prepared in r->text_buf | |
1349 | */ | |
1350 | for (;;) { | |
1351 | next = memchr(text, '\n', text_len); | |
3ce9a7c0 | 1352 | if (next) { |
896fbe20 | 1353 | line_len = next - text; |
3ce9a7c0 | 1354 | } else { |
896fbe20 JO |
1355 | /* Drop truncated line(s). */ |
1356 | if (truncated) | |
1357 | break; | |
1358 | line_len = text_len; | |
3ce9a7c0 | 1359 | } |
7ff9554b | 1360 | |
896fbe20 JO |
1361 | /* |
1362 | * Truncate the text if there is not enough space to add the | |
f0e386ee | 1363 | * prefix and a trailing newline and a terminator. |
896fbe20 | 1364 | */ |
f0e386ee | 1365 | if (len + prefix_len + text_len + 1 + 1 > buf_size) { |
896fbe20 | 1366 | /* Drop even the current line if no space. */ |
f0e386ee | 1367 | if (len + prefix_len + line_len + 1 + 1 > buf_size) |
3ce9a7c0 | 1368 | break; |
7ff9554b | 1369 | |
f0e386ee | 1370 | text_len = buf_size - len - prefix_len - 1 - 1; |
896fbe20 | 1371 | truncated = true; |
3ce9a7c0 | 1372 | } |
7ff9554b | 1373 | |
896fbe20 JO |
1374 | memmove(text + prefix_len, text, text_len); |
1375 | memcpy(text, prefix, prefix_len); | |
1376 | ||
f0e386ee JO |
1377 | /* |
1378 | * Increment the prepared length to include the text and | |
1379 | * prefix that were just moved+copied. Also increment for the | |
1380 | * newline at the end of this line. If this is the last line, | |
1381 | * there is no newline, but it will be added immediately below. | |
1382 | */ | |
896fbe20 | 1383 | len += prefix_len + line_len + 1; |
896fbe20 JO |
1384 | if (text_len == line_len) { |
1385 | /* | |
f0e386ee JO |
1386 | * This is the last line. Add the trailing newline |
1387 | * removed in vprintk_store(). | |
896fbe20 JO |
1388 | */ |
1389 | text[prefix_len + line_len] = '\n'; | |
1390 | break; | |
1391 | } | |
1392 | ||
1393 | /* | |
1394 | * Advance beyond the added prefix and the related line with | |
1395 | * its newline. | |
1396 | */ | |
1397 | text += prefix_len + line_len + 1; | |
1398 | ||
1399 | /* | |
1400 | * The remaining text has only decreased by the line with its | |
1401 | * newline. | |
1402 | * | |
1403 | * Note that @text_len can become zero. It happens when @text | |
1404 | * ended with a newline (either due to truncation or the | |
1405 | * original string ending with "\n\n"). The loop is correctly | |
1406 | * repeated and (if not truncated) an empty line with a prefix | |
1407 | * will be prepared. | |
1408 | */ | |
1409 | text_len -= line_len + 1; | |
1410 | } | |
7ff9554b | 1411 | |
f0e386ee JO |
1412 | /* |
1413 | * If a buffer was provided, it will be terminated. Space for the | |
1414 | * string terminator is guaranteed to be available. The terminator is | |
1415 | * not counted in the return value. | |
1416 | */ | |
1417 | if (buf_size > 0) | |
08d60e59 | 1418 | r->text_buf[len] = 0; |
f0e386ee | 1419 | |
7ff9554b KS |
1420 | return len; |
1421 | } | |
1422 | ||
896fbe20 JO |
1423 | static size_t get_record_print_text_size(struct printk_info *info, |
1424 | unsigned int line_count, | |
1425 | bool syslog, bool time) | |
1426 | { | |
1427 | char prefix[PREFIX_MAX]; | |
1428 | size_t prefix_len; | |
1429 | ||
1430 | prefix_len = info_print_prefix(info, syslog, time, prefix); | |
1431 | ||
1432 | /* | |
1433 | * Each line will be preceded with a prefix. The intermediate | |
1434 | * newlines are already within the text, but a final trailing | |
1435 | * newline will be added. | |
1436 | */ | |
1437 | return ((prefix_len * line_count) + info->text_len + 1); | |
1438 | } | |
1439 | ||
4260e0e5 JO |
1440 | /* |
1441 | * Beginning with @start_seq, find the first record where it and all following | |
1442 | * records up to (but not including) @max_seq fit into @size. | |
1443 | * | |
1444 | * @max_seq is simply an upper bound and does not need to exist. If the caller | |
1445 | * does not require an upper bound, -1 can be used for @max_seq. | |
1446 | */ | |
1447 | static u64 find_first_fitting_seq(u64 start_seq, u64 max_seq, size_t size, | |
1448 | bool syslog, bool time) | |
1449 | { | |
1450 | struct printk_info info; | |
1451 | unsigned int line_count; | |
1452 | size_t len = 0; | |
1453 | u64 seq; | |
1454 | ||
1455 | /* Determine the size of the records up to @max_seq. */ | |
1456 | prb_for_each_info(start_seq, prb, seq, &info, &line_count) { | |
1457 | if (info.seq >= max_seq) | |
1458 | break; | |
1459 | len += get_record_print_text_size(&info, line_count, syslog, time); | |
1460 | } | |
1461 | ||
1462 | /* | |
1463 | * Adjust the upper bound for the next loop to avoid subtracting | |
1464 | * lengths that were never added. | |
1465 | */ | |
1466 | if (seq < max_seq) | |
1467 | max_seq = seq; | |
1468 | ||
1469 | /* | |
1470 | * Move first record forward until length fits into the buffer. Ignore | |
1471 | * newest messages that were not counted in the above cycle. Messages | |
1472 | * might appear and get lost in the meantime. This is a best effort | |
1473 | * that prevents an infinite loop that could occur with a retry. | |
1474 | */ | |
1475 | prb_for_each_info(start_seq, prb, seq, &info, &line_count) { | |
1476 | if (len <= size || info.seq >= max_seq) | |
1477 | break; | |
1478 | len -= get_record_print_text_size(&info, line_count, syslog, time); | |
1479 | } | |
1480 | ||
1481 | return seq; | |
1482 | } | |
1483 | ||
7ff9554b KS |
1484 | static int syslog_print(char __user *buf, int size) |
1485 | { | |
896fbe20 JO |
1486 | struct printk_info info; |
1487 | struct printk_record r; | |
7ff9554b | 1488 | char *text; |
116e90b2 | 1489 | int len = 0; |
7ff9554b | 1490 | |
cf5b0208 | 1491 | text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL); |
7ff9554b KS |
1492 | if (!text) |
1493 | return -ENOMEM; | |
1494 | ||
cf5b0208 | 1495 | prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX); |
896fbe20 | 1496 | |
116e90b2 JB |
1497 | while (size > 0) { |
1498 | size_t n; | |
eb02dac9 | 1499 | size_t skip; |
116e90b2 | 1500 | |
996e9666 | 1501 | printk_safe_enter_irq(); |
636babdc | 1502 | raw_spin_lock(&syslog_lock); |
896fbe20 | 1503 | if (!prb_read_valid(prb, syslog_seq, &r)) { |
636babdc | 1504 | raw_spin_unlock(&syslog_lock); |
996e9666 | 1505 | printk_safe_exit_irq(); |
116e90b2 JB |
1506 | break; |
1507 | } | |
896fbe20 JO |
1508 | if (r.info->seq != syslog_seq) { |
1509 | /* message is gone, move to next valid one */ | |
1510 | syslog_seq = r.info->seq; | |
1511 | syslog_partial = 0; | |
1512 | } | |
eb02dac9 | 1513 | |
e80c1a9d TH |
1514 | /* |
1515 | * To keep reading/counting partial line consistent, | |
1516 | * use printk_time value as of the beginning of a line. | |
1517 | */ | |
1518 | if (!syslog_partial) | |
1519 | syslog_time = printk_time; | |
1520 | ||
eb02dac9 | 1521 | skip = syslog_partial; |
896fbe20 | 1522 | n = record_print_text(&r, true, syslog_time); |
eb02dac9 KS |
1523 | if (n - syslog_partial <= size) { |
1524 | /* message fits into buffer, move forward */ | |
896fbe20 | 1525 | syslog_seq = r.info->seq + 1; |
eb02dac9 KS |
1526 | n -= syslog_partial; |
1527 | syslog_partial = 0; | |
1528 | } else if (!len){ | |
1529 | /* partial read(), remember position */ | |
1530 | n = size; | |
1531 | syslog_partial += n; | |
116e90b2 JB |
1532 | } else |
1533 | n = 0; | |
636babdc | 1534 | raw_spin_unlock(&syslog_lock); |
996e9666 | 1535 | printk_safe_exit_irq(); |
116e90b2 JB |
1536 | |
1537 | if (!n) | |
1538 | break; | |
1539 | ||
eb02dac9 | 1540 | if (copy_to_user(buf, text + skip, n)) { |
116e90b2 JB |
1541 | if (!len) |
1542 | len = -EFAULT; | |
1543 | break; | |
1544 | } | |
eb02dac9 KS |
1545 | |
1546 | len += n; | |
1547 | size -= n; | |
1548 | buf += n; | |
7ff9554b | 1549 | } |
7ff9554b KS |
1550 | |
1551 | kfree(text); | |
1552 | return len; | |
1553 | } | |
1554 | ||
1555 | static int syslog_print_all(char __user *buf, int size, bool clear) | |
1556 | { | |
896fbe20 | 1557 | struct printk_info info; |
896fbe20 | 1558 | struct printk_record r; |
7ff9554b KS |
1559 | char *text; |
1560 | int len = 0; | |
63842c21 | 1561 | u64 seq; |
e80c1a9d | 1562 | bool time; |
63842c21 | 1563 | |
cf5b0208 | 1564 | text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL); |
7ff9554b KS |
1565 | if (!text) |
1566 | return -ENOMEM; | |
1567 | ||
e80c1a9d | 1568 | time = printk_time; |
996e9666 | 1569 | printk_safe_enter_irq(); |
63842c21 NG |
1570 | /* |
1571 | * Find first record that fits, including all following records, | |
1572 | * into the user-provided buffer for this dump. | |
1573 | */ | |
7d7a23a9 JO |
1574 | seq = find_first_fitting_seq(latched_seq_read_nolock(&clear_seq), -1, |
1575 | size, true, time); | |
7ff9554b | 1576 | |
cf5b0208 | 1577 | prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX); |
7ff9554b | 1578 | |
63842c21 | 1579 | len = 0; |
896fbe20 JO |
1580 | prb_for_each_record(seq, prb, seq, &r) { |
1581 | int textlen; | |
7ff9554b | 1582 | |
896fbe20 JO |
1583 | textlen = record_print_text(&r, true, time); |
1584 | ||
1585 | if (len + textlen > size) { | |
1586 | seq--; | |
1587 | break; | |
1588 | } | |
7ff9554b | 1589 | |
996e9666 | 1590 | printk_safe_exit_irq(); |
63842c21 NG |
1591 | if (copy_to_user(buf + len, text, textlen)) |
1592 | len = -EFAULT; | |
1593 | else | |
1594 | len += textlen; | |
996e9666 | 1595 | printk_safe_enter_irq(); |
7ff9554b | 1596 | |
896fbe20 JO |
1597 | if (len < 0) |
1598 | break; | |
7ff9554b KS |
1599 | } |
1600 | ||
636babdc JO |
1601 | if (clear) { |
1602 | raw_spin_lock(&syslog_lock); | |
7d7a23a9 | 1603 | latched_seq_write(&clear_seq, seq); |
636babdc JO |
1604 | raw_spin_unlock(&syslog_lock); |
1605 | } | |
996e9666 | 1606 | printk_safe_exit_irq(); |
7ff9554b KS |
1607 | |
1608 | kfree(text); | |
1609 | return len; | |
1610 | } | |
1611 | ||
8599dc7d PM |
1612 | static void syslog_clear(void) |
1613 | { | |
996e9666 | 1614 | printk_safe_enter_irq(); |
636babdc | 1615 | raw_spin_lock(&syslog_lock); |
7d7a23a9 | 1616 | latched_seq_write(&clear_seq, prb_next_seq(prb)); |
636babdc | 1617 | raw_spin_unlock(&syslog_lock); |
996e9666 | 1618 | printk_safe_exit_irq(); |
8599dc7d PM |
1619 | } |
1620 | ||
636babdc JO |
1621 | /* Return a consistent copy of @syslog_seq. */ |
1622 | static u64 read_syslog_seq_irq(void) | |
1623 | { | |
1624 | u64 seq; | |
1625 | ||
1626 | raw_spin_lock_irq(&syslog_lock); | |
1627 | seq = syslog_seq; | |
1628 | raw_spin_unlock_irq(&syslog_lock); | |
1629 | ||
1630 | return seq; | |
1631 | } | |
1632 | ||
3ea4331c | 1633 | int do_syslog(int type, char __user *buf, int len, int source) |
1da177e4 | 1634 | { |
13791c80 | 1635 | struct printk_info info; |
7ff9554b | 1636 | bool clear = false; |
a39d4a85 | 1637 | static int saved_console_loglevel = LOGLEVEL_DEFAULT; |
ee24aebf | 1638 | int error; |
1da177e4 | 1639 | |
3ea4331c | 1640 | error = check_syslog_permissions(type, source); |
ee24aebf | 1641 | if (error) |
077a1cc0 | 1642 | return error; |
12b3052c | 1643 | |
1da177e4 | 1644 | switch (type) { |
d78ca3cd | 1645 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 1646 | break; |
d78ca3cd | 1647 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 1648 | break; |
d78ca3cd | 1649 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 | 1650 | if (!buf || len < 0) |
077a1cc0 | 1651 | return -EINVAL; |
1da177e4 | 1652 | if (!len) |
077a1cc0 | 1653 | return 0; |
96d4f267 | 1654 | if (!access_ok(buf, len)) |
077a1cc0 | 1655 | return -EFAULT; |
636babdc | 1656 | |
40dc5651 | 1657 | error = wait_event_interruptible(log_wait, |
636babdc | 1658 | prb_read_valid(prb, read_syslog_seq_irq(), NULL)); |
cb424ffe | 1659 | if (error) |
077a1cc0 | 1660 | return error; |
7ff9554b | 1661 | error = syslog_print(buf, len); |
1da177e4 | 1662 | break; |
d78ca3cd KC |
1663 | /* Read/clear last kernel messages */ |
1664 | case SYSLOG_ACTION_READ_CLEAR: | |
7ff9554b | 1665 | clear = true; |
4e797e6e | 1666 | fallthrough; |
d78ca3cd KC |
1667 | /* Read last kernel messages */ |
1668 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 | 1669 | if (!buf || len < 0) |
077a1cc0 | 1670 | return -EINVAL; |
1da177e4 | 1671 | if (!len) |
077a1cc0 | 1672 | return 0; |
96d4f267 | 1673 | if (!access_ok(buf, len)) |
077a1cc0 | 1674 | return -EFAULT; |
7ff9554b | 1675 | error = syslog_print_all(buf, len, clear); |
1da177e4 | 1676 | break; |
d78ca3cd KC |
1677 | /* Clear ring buffer */ |
1678 | case SYSLOG_ACTION_CLEAR: | |
8599dc7d | 1679 | syslog_clear(); |
4661e356 | 1680 | break; |
d78ca3cd KC |
1681 | /* Disable logging to console */ |
1682 | case SYSLOG_ACTION_CONSOLE_OFF: | |
a39d4a85 | 1683 | if (saved_console_loglevel == LOGLEVEL_DEFAULT) |
1aaad49e | 1684 | saved_console_loglevel = console_loglevel; |
1da177e4 LT |
1685 | console_loglevel = minimum_console_loglevel; |
1686 | break; | |
d78ca3cd KC |
1687 | /* Enable logging to console */ |
1688 | case SYSLOG_ACTION_CONSOLE_ON: | |
a39d4a85 | 1689 | if (saved_console_loglevel != LOGLEVEL_DEFAULT) { |
1aaad49e | 1690 | console_loglevel = saved_console_loglevel; |
a39d4a85 | 1691 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1aaad49e | 1692 | } |
1da177e4 | 1693 | break; |
d78ca3cd KC |
1694 | /* Set level of messages printed to console */ |
1695 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 | 1696 | if (len < 1 || len > 8) |
077a1cc0 | 1697 | return -EINVAL; |
1da177e4 LT |
1698 | if (len < minimum_console_loglevel) |
1699 | len = minimum_console_loglevel; | |
1700 | console_loglevel = len; | |
1aaad49e | 1701 | /* Implicitly re-enable logging to console */ |
a39d4a85 | 1702 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1da177e4 | 1703 | break; |
d78ca3cd KC |
1704 | /* Number of chars in the log buffer */ |
1705 | case SYSLOG_ACTION_SIZE_UNREAD: | |
996e9666 | 1706 | printk_safe_enter_irq(); |
636babdc | 1707 | raw_spin_lock(&syslog_lock); |
13791c80 JO |
1708 | if (!prb_read_valid_info(prb, syslog_seq, &info, NULL)) { |
1709 | /* No unread messages. */ | |
636babdc | 1710 | raw_spin_unlock(&syslog_lock); |
996e9666 | 1711 | printk_safe_exit_irq(); |
13791c80 JO |
1712 | return 0; |
1713 | } | |
1714 | if (info.seq != syslog_seq) { | |
7ff9554b | 1715 | /* messages are gone, move to first one */ |
13791c80 | 1716 | syslog_seq = info.seq; |
eb02dac9 | 1717 | syslog_partial = 0; |
7ff9554b | 1718 | } |
3ea4331c | 1719 | if (source == SYSLOG_FROM_PROC) { |
7ff9554b KS |
1720 | /* |
1721 | * Short-cut for poll(/"proc/kmsg") which simply checks | |
1722 | * for pending data, not the size; return the count of | |
1723 | * records, not the length. | |
1724 | */ | |
896fbe20 | 1725 | error = prb_next_seq(prb) - syslog_seq; |
7ff9554b | 1726 | } else { |
e80c1a9d | 1727 | bool time = syslog_partial ? syslog_time : printk_time; |
896fbe20 JO |
1728 | unsigned int line_count; |
1729 | u64 seq; | |
1730 | ||
1731 | prb_for_each_info(syslog_seq, prb, seq, &info, | |
1732 | &line_count) { | |
1733 | error += get_record_print_text_size(&info, line_count, | |
1734 | true, time); | |
e80c1a9d | 1735 | time = printk_time; |
7ff9554b | 1736 | } |
eb02dac9 | 1737 | error -= syslog_partial; |
7ff9554b | 1738 | } |
636babdc | 1739 | raw_spin_unlock(&syslog_lock); |
996e9666 | 1740 | printk_safe_exit_irq(); |
1da177e4 | 1741 | break; |
d78ca3cd KC |
1742 | /* Size of the log buffer */ |
1743 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
1744 | error = log_buf_len; |
1745 | break; | |
1746 | default: | |
1747 | error = -EINVAL; | |
1748 | break; | |
1749 | } | |
077a1cc0 | 1750 | |
1da177e4 LT |
1751 | return error; |
1752 | } | |
1753 | ||
1e7bfb21 | 1754 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 1755 | { |
637241a9 | 1756 | return do_syslog(type, buf, len, SYSLOG_FROM_READER); |
1da177e4 LT |
1757 | } |
1758 | ||
c162d5b4 PM |
1759 | /* |
1760 | * Special console_lock variants that help to reduce the risk of soft-lockups. | |
1761 | * They allow to pass console_lock to another printk() call using a busy wait. | |
1762 | */ | |
1763 | ||
1764 | #ifdef CONFIG_LOCKDEP | |
1765 | static struct lockdep_map console_owner_dep_map = { | |
1766 | .name = "console_owner" | |
1767 | }; | |
1768 | #endif | |
1769 | ||
1770 | static DEFINE_RAW_SPINLOCK(console_owner_lock); | |
1771 | static struct task_struct *console_owner; | |
1772 | static bool console_waiter; | |
1773 | ||
1774 | /** | |
1775 | * console_lock_spinning_enable - mark beginning of code where another | |
1776 | * thread might safely busy wait | |
1777 | * | |
1778 | * This basically converts console_lock into a spinlock. This marks | |
1779 | * the section where the console_lock owner can not sleep, because | |
1780 | * there may be a waiter spinning (like a spinlock). Also it must be | |
1781 | * ready to hand over the lock at the end of the section. | |
1782 | */ | |
1783 | static void console_lock_spinning_enable(void) | |
1784 | { | |
1785 | raw_spin_lock(&console_owner_lock); | |
1786 | console_owner = current; | |
1787 | raw_spin_unlock(&console_owner_lock); | |
1788 | ||
1789 | /* The waiter may spin on us after setting console_owner */ | |
1790 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
1791 | } | |
1792 | ||
1793 | /** | |
1794 | * console_lock_spinning_disable_and_check - mark end of code where another | |
1795 | * thread was able to busy wait and check if there is a waiter | |
1796 | * | |
1797 | * This is called at the end of the section where spinning is allowed. | |
1798 | * It has two functions. First, it is a signal that it is no longer | |
1799 | * safe to start busy waiting for the lock. Second, it checks if | |
1800 | * there is a busy waiter and passes the lock rights to her. | |
1801 | * | |
1802 | * Important: Callers lose the lock if there was a busy waiter. | |
1803 | * They must not touch items synchronized by console_lock | |
1804 | * in this case. | |
1805 | * | |
1806 | * Return: 1 if the lock rights were passed, 0 otherwise. | |
1807 | */ | |
1808 | static int console_lock_spinning_disable_and_check(void) | |
1809 | { | |
1810 | int waiter; | |
1811 | ||
1812 | raw_spin_lock(&console_owner_lock); | |
1813 | waiter = READ_ONCE(console_waiter); | |
1814 | console_owner = NULL; | |
1815 | raw_spin_unlock(&console_owner_lock); | |
1816 | ||
1817 | if (!waiter) { | |
5facae4f | 1818 | spin_release(&console_owner_dep_map, _THIS_IP_); |
c162d5b4 PM |
1819 | return 0; |
1820 | } | |
1821 | ||
1822 | /* The waiter is now free to continue */ | |
1823 | WRITE_ONCE(console_waiter, false); | |
1824 | ||
5facae4f | 1825 | spin_release(&console_owner_dep_map, _THIS_IP_); |
c162d5b4 PM |
1826 | |
1827 | /* | |
1828 | * Hand off console_lock to waiter. The waiter will perform | |
1829 | * the up(). After this, the waiter is the console_lock owner. | |
1830 | */ | |
5facae4f | 1831 | mutex_release(&console_lock_dep_map, _THIS_IP_); |
c162d5b4 PM |
1832 | return 1; |
1833 | } | |
1834 | ||
1835 | /** | |
1836 | * console_trylock_spinning - try to get console_lock by busy waiting | |
1837 | * | |
1838 | * This allows to busy wait for the console_lock when the current | |
1839 | * owner is running in specially marked sections. It means that | |
1840 | * the current owner is running and cannot reschedule until it | |
1841 | * is ready to lose the lock. | |
1842 | * | |
1843 | * Return: 1 if we got the lock, 0 othrewise | |
1844 | */ | |
1845 | static int console_trylock_spinning(void) | |
1846 | { | |
1847 | struct task_struct *owner = NULL; | |
1848 | bool waiter; | |
1849 | bool spin = false; | |
1850 | unsigned long flags; | |
1851 | ||
1852 | if (console_trylock()) | |
1853 | return 1; | |
1854 | ||
1855 | printk_safe_enter_irqsave(flags); | |
1856 | ||
1857 | raw_spin_lock(&console_owner_lock); | |
1858 | owner = READ_ONCE(console_owner); | |
1859 | waiter = READ_ONCE(console_waiter); | |
1860 | if (!waiter && owner && owner != current) { | |
1861 | WRITE_ONCE(console_waiter, true); | |
1862 | spin = true; | |
1863 | } | |
1864 | raw_spin_unlock(&console_owner_lock); | |
1865 | ||
1866 | /* | |
1867 | * If there is an active printk() writing to the | |
1868 | * consoles, instead of having it write our data too, | |
1869 | * see if we can offload that load from the active | |
1870 | * printer, and do some printing ourselves. | |
1871 | * Go into a spin only if there isn't already a waiter | |
1872 | * spinning, and there is an active printer, and | |
1873 | * that active printer isn't us (recursive printk?). | |
1874 | */ | |
1875 | if (!spin) { | |
1876 | printk_safe_exit_irqrestore(flags); | |
1877 | return 0; | |
1878 | } | |
1879 | ||
1880 | /* We spin waiting for the owner to release us */ | |
1881 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
1882 | /* Owner will clear console_waiter on hand off */ | |
1883 | while (READ_ONCE(console_waiter)) | |
1884 | cpu_relax(); | |
5facae4f | 1885 | spin_release(&console_owner_dep_map, _THIS_IP_); |
c162d5b4 PM |
1886 | |
1887 | printk_safe_exit_irqrestore(flags); | |
1888 | /* | |
1889 | * The owner passed the console lock to us. | |
1890 | * Since we did not spin on console lock, annotate | |
1891 | * this as a trylock. Otherwise lockdep will | |
1892 | * complain. | |
1893 | */ | |
1894 | mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_); | |
1895 | ||
1896 | return 1; | |
1897 | } | |
1898 | ||
1da177e4 LT |
1899 | /* |
1900 | * Call the console drivers, asking them to write out | |
1901 | * log_buf[start] to log_buf[end - 1]. | |
ac751efa | 1902 | * The console_lock must be held. |
1da177e4 | 1903 | */ |
d9c23523 | 1904 | static void call_console_drivers(const char *ext_text, size_t ext_len, |
6fe29354 | 1905 | const char *text, size_t len) |
1da177e4 | 1906 | { |
896fbe20 JO |
1907 | static char dropped_text[64]; |
1908 | size_t dropped_len = 0; | |
7ff9554b | 1909 | struct console *con; |
1da177e4 | 1910 | |
fc98c3c8 | 1911 | trace_console_rcuidle(text, len); |
7ff9554b | 1912 | |
896fbe20 JO |
1913 | if (!console_drivers) |
1914 | return; | |
1915 | ||
1916 | if (console_dropped) { | |
1917 | dropped_len = snprintf(dropped_text, sizeof(dropped_text), | |
1918 | "** %lu printk messages dropped **\n", | |
1919 | console_dropped); | |
1920 | console_dropped = 0; | |
1921 | } | |
1922 | ||
7ff9554b KS |
1923 | for_each_console(con) { |
1924 | if (exclusive_console && con != exclusive_console) | |
1925 | continue; | |
1926 | if (!(con->flags & CON_ENABLED)) | |
1927 | continue; | |
1928 | if (!con->write) | |
1929 | continue; | |
1930 | if (!cpu_online(smp_processor_id()) && | |
1931 | !(con->flags & CON_ANYTIME)) | |
1932 | continue; | |
6fe29354 TH |
1933 | if (con->flags & CON_EXTENDED) |
1934 | con->write(con, ext_text, ext_len); | |
896fbe20 JO |
1935 | else { |
1936 | if (dropped_len) | |
1937 | con->write(con, dropped_text, dropped_len); | |
6fe29354 | 1938 | con->write(con, text, len); |
896fbe20 | 1939 | } |
7ff9554b | 1940 | } |
1da177e4 LT |
1941 | } |
1942 | ||
af91322e DY |
1943 | int printk_delay_msec __read_mostly; |
1944 | ||
1945 | static inline void printk_delay(void) | |
1946 | { | |
1947 | if (unlikely(printk_delay_msec)) { | |
1948 | int m = printk_delay_msec; | |
1949 | ||
1950 | while (m--) { | |
1951 | mdelay(1); | |
1952 | touch_nmi_watchdog(); | |
1953 | } | |
1954 | } | |
1955 | } | |
1956 | ||
cbae05d3 TH |
1957 | static inline u32 printk_caller_id(void) |
1958 | { | |
1959 | return in_task() ? task_pid_nr(current) : | |
1960 | 0x80000000 + raw_smp_processor_id(); | |
1961 | } | |
1962 | ||
b031a684 JO |
1963 | /** |
1964 | * parse_prefix - Parse level and control flags. | |
1965 | * | |
1966 | * @text: The terminated text message. | |
1967 | * @level: A pointer to the current level value, will be updated. | |
1968 | * @lflags: A pointer to the current log flags, will be updated. | |
1969 | * | |
1970 | * @level may be NULL if the caller is not interested in the parsed value. | |
1971 | * Otherwise the variable pointed to by @level must be set to | |
1972 | * LOGLEVEL_DEFAULT in order to be updated with the parsed value. | |
1973 | * | |
1974 | * @lflags may be NULL if the caller is not interested in the parsed value. | |
1975 | * Otherwise the variable pointed to by @lflags will be OR'd with the parsed | |
1976 | * value. | |
1977 | * | |
1978 | * Return: The length of the parsed level and control flags. | |
1979 | */ | |
1980 | static u16 parse_prefix(char *text, int *level, enum log_flags *lflags) | |
c362c7ff | 1981 | { |
b031a684 JO |
1982 | u16 prefix_len = 0; |
1983 | int kern_level; | |
cbae05d3 | 1984 | |
b031a684 JO |
1985 | while (*text) { |
1986 | kern_level = printk_get_level(text); | |
1987 | if (!kern_level) | |
1988 | break; | |
f5f022e5 | 1989 | |
b031a684 JO |
1990 | switch (kern_level) { |
1991 | case '0' ... '7': | |
1992 | if (level && *level == LOGLEVEL_DEFAULT) | |
1993 | *level = kern_level - '0'; | |
1994 | break; | |
1995 | case 'c': /* KERN_CONT */ | |
1996 | if (lflags) | |
1997 | *lflags |= LOG_CONT; | |
1998 | } | |
1999 | ||
2000 | prefix_len += 2; | |
2001 | text += 2; | |
2002 | } | |
2003 | ||
2004 | return prefix_len; | |
2005 | } | |
2006 | ||
2007 | static u16 printk_sprint(char *text, u16 size, int facility, enum log_flags *lflags, | |
2008 | const char *fmt, va_list args) | |
2009 | { | |
2010 | u16 text_len; | |
2011 | ||
2012 | text_len = vscnprintf(text, size, fmt, args); | |
2013 | ||
2014 | /* Mark and strip a trailing newline. */ | |
2015 | if (text_len && text[text_len - 1] == '\n') { | |
2016 | text_len--; | |
2017 | *lflags |= LOG_NEWLINE; | |
2018 | } | |
2019 | ||
2020 | /* Strip log level and control flags. */ | |
2021 | if (facility == 0) { | |
2022 | u16 prefix_len; | |
2023 | ||
2024 | prefix_len = parse_prefix(text, NULL, NULL); | |
2025 | if (prefix_len) { | |
2026 | text_len -= prefix_len; | |
2027 | memmove(text, text + prefix_len, text_len); | |
f5f022e5 | 2028 | } |
c362c7ff LT |
2029 | } |
2030 | ||
b031a684 | 2031 | return text_len; |
c362c7ff LT |
2032 | } |
2033 | ||
b031a684 | 2034 | __printf(4, 0) |
ba552399 | 2035 | int vprintk_store(int facility, int level, |
74caba7f | 2036 | const struct dev_printk_info *dev_info, |
ba552399 | 2037 | const char *fmt, va_list args) |
1da177e4 | 2038 | { |
6b916706 | 2039 | const u32 caller_id = printk_caller_id(); |
6b916706 | 2040 | struct prb_reserved_entry e; |
5becfb1d | 2041 | enum log_flags lflags = 0; |
6b916706 JO |
2042 | struct printk_record r; |
2043 | u16 trunc_msg_len = 0; | |
b031a684 JO |
2044 | char prefix_buf[8]; |
2045 | u16 reserve_size; | |
2046 | va_list args2; | |
6b916706 JO |
2047 | u16 text_len; |
2048 | u64 ts_nsec; | |
bfe8df3d | 2049 | |
7ff9554b | 2050 | /* |
6b916706 JO |
2051 | * Since the duration of printk() can vary depending on the message |
2052 | * and state of the ringbuffer, grab the timestamp now so that it is | |
2053 | * close to the call of printk(). This provides a more deterministic | |
2054 | * timestamp with respect to the caller. | |
7ff9554b | 2055 | */ |
6b916706 | 2056 | ts_nsec = local_clock(); |
5fd29d6c | 2057 | |
7ff9554b | 2058 | /* |
b031a684 JO |
2059 | * The sprintf needs to come first since the syslog prefix might be |
2060 | * passed in as a parameter. An extra byte must be reserved so that | |
2061 | * later the vscnprintf() into the reserved buffer has room for the | |
2062 | * terminating '\0', which is not counted by vsnprintf(). | |
7ff9554b | 2063 | */ |
b031a684 JO |
2064 | va_copy(args2, args); |
2065 | reserve_size = vsnprintf(&prefix_buf[0], sizeof(prefix_buf), fmt, args2) + 1; | |
2066 | va_end(args2); | |
9d90c8d9 | 2067 | |
b031a684 JO |
2068 | if (reserve_size > LOG_LINE_MAX) |
2069 | reserve_size = LOG_LINE_MAX; | |
088a52aa | 2070 | |
b031a684 JO |
2071 | /* Extract log level or control flags. */ |
2072 | if (facility == 0) | |
2073 | parse_prefix(&prefix_buf[0], &level, &lflags); | |
5fd29d6c | 2074 | |
a39d4a85 | 2075 | if (level == LOGLEVEL_DEFAULT) |
c313af14 | 2076 | level = default_message_loglevel; |
9d90c8d9 | 2077 | |
74caba7f | 2078 | if (dev_info) |
5becfb1d | 2079 | lflags |= LOG_NEWLINE; |
9d90c8d9 | 2080 | |
6b916706 | 2081 | if (lflags & LOG_CONT) { |
b031a684 | 2082 | prb_rec_init_wr(&r, reserve_size); |
6b916706 | 2083 | if (prb_reserve_in_last(&e, prb, &r, caller_id, LOG_LINE_MAX)) { |
b031a684 JO |
2084 | text_len = printk_sprint(&r.text_buf[r.info->text_len], reserve_size, |
2085 | facility, &lflags, fmt, args); | |
6b916706 | 2086 | r.info->text_len += text_len; |
088a52aa | 2087 | |
6b916706 JO |
2088 | if (lflags & LOG_NEWLINE) { |
2089 | r.info->flags |= LOG_NEWLINE; | |
2090 | prb_final_commit(&e); | |
2091 | } else { | |
2092 | prb_commit(&e); | |
088a52aa | 2093 | } |
4bcc595c | 2094 | |
6b916706 | 2095 | return text_len; |
5fd29d6c LT |
2096 | } |
2097 | } | |
2098 | ||
6b916706 JO |
2099 | /* |
2100 | * Explicitly initialize the record before every prb_reserve() call. | |
2101 | * prb_reserve_in_last() and prb_reserve() purposely invalidate the | |
2102 | * structure when they fail. | |
2103 | */ | |
b031a684 | 2104 | prb_rec_init_wr(&r, reserve_size); |
6b916706 JO |
2105 | if (!prb_reserve(&e, prb, &r)) { |
2106 | /* truncate the message if it is too long for empty buffer */ | |
b031a684 | 2107 | truncate_msg(&reserve_size, &trunc_msg_len); |
9d90c8d9 | 2108 | |
b031a684 | 2109 | prb_rec_init_wr(&r, reserve_size + trunc_msg_len); |
6b916706 JO |
2110 | if (!prb_reserve(&e, prb, &r)) |
2111 | return 0; | |
2112 | } | |
2113 | ||
2114 | /* fill message */ | |
b031a684 | 2115 | text_len = printk_sprint(&r.text_buf[0], reserve_size, facility, &lflags, fmt, args); |
6b916706 JO |
2116 | if (trunc_msg_len) |
2117 | memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len); | |
2118 | r.info->text_len = text_len + trunc_msg_len; | |
2119 | r.info->facility = facility; | |
2120 | r.info->level = level & 7; | |
2121 | r.info->flags = lflags & 0x1f; | |
2122 | r.info->ts_nsec = ts_nsec; | |
2123 | r.info->caller_id = caller_id; | |
74caba7f | 2124 | if (dev_info) |
6b916706 | 2125 | memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info)); |
ac60ad74 | 2126 | |
6b916706 JO |
2127 | /* A message without a trailing newline can be continued. */ |
2128 | if (!(lflags & LOG_NEWLINE)) | |
2129 | prb_commit(&e); | |
2130 | else | |
2131 | prb_final_commit(&e); | |
2132 | ||
2133 | return (text_len + trunc_msg_len); | |
ba552399 | 2134 | } |
1da177e4 | 2135 | |
ba552399 | 2136 | asmlinkage int vprintk_emit(int facility, int level, |
74caba7f | 2137 | const struct dev_printk_info *dev_info, |
ba552399 PM |
2138 | const char *fmt, va_list args) |
2139 | { | |
2140 | int printed_len; | |
8749efc0 | 2141 | bool in_sched = false; |
ba552399 PM |
2142 | unsigned long flags; |
2143 | ||
c39ea0b9 FT |
2144 | /* Suppress unimportant messages after panic happens */ |
2145 | if (unlikely(suppress_printk)) | |
2146 | return 0; | |
2147 | ||
ba552399 PM |
2148 | if (level == LOGLEVEL_SCHED) { |
2149 | level = LOGLEVEL_DEFAULT; | |
2150 | in_sched = true; | |
2151 | } | |
2152 | ||
2153 | boot_delay_msec(level); | |
2154 | printk_delay(); | |
2155 | ||
b031a684 | 2156 | printk_safe_enter_irqsave(flags); |
74caba7f | 2157 | printed_len = vprintk_store(facility, level, dev_info, fmt, args); |
b031a684 | 2158 | printk_safe_exit_irqrestore(flags); |
939f04be | 2159 | |
458df9fd | 2160 | /* If called from the scheduler, we can not call up(). */ |
8749efc0 | 2161 | if (!in_sched) { |
fd5f7cde SS |
2162 | /* |
2163 | * Disable preemption to avoid being preempted while holding | |
2164 | * console_sem which would prevent anyone from printing to | |
2165 | * console | |
2166 | */ | |
2167 | preempt_disable(); | |
d18bbc21 AM |
2168 | /* |
2169 | * Try to acquire and then immediately release the console | |
2170 | * semaphore. The release will print out buffers and wake up | |
2171 | * /dev/kmsg and syslog() users. | |
2172 | */ | |
c162d5b4 | 2173 | if (console_trylock_spinning()) |
d18bbc21 | 2174 | console_unlock(); |
fd5f7cde | 2175 | preempt_enable(); |
d18bbc21 | 2176 | } |
76a8ad29 | 2177 | |
8749efc0 | 2178 | wake_up_klogd(); |
1da177e4 LT |
2179 | return printed_len; |
2180 | } | |
7ff9554b KS |
2181 | EXPORT_SYMBOL(vprintk_emit); |
2182 | ||
a0cba217 | 2183 | int vprintk_default(const char *fmt, va_list args) |
afdc34a3 | 2184 | { |
74caba7f | 2185 | return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, fmt, args); |
afdc34a3 SRRH |
2186 | } |
2187 | EXPORT_SYMBOL_GPL(vprintk_default); | |
2188 | ||
7ff9554b KS |
2189 | /** |
2190 | * printk - print a kernel message | |
2191 | * @fmt: format string | |
2192 | * | |
2193 | * This is printk(). It can be called from any context. We want it to work. | |
2194 | * | |
2195 | * We try to grab the console_lock. If we succeed, it's easy - we log the | |
2196 | * output and call the console drivers. If we fail to get the semaphore, we | |
2197 | * place the output into the log buffer and return. The current holder of | |
2198 | * the console_sem will notice the new output in console_unlock(); and will | |
2199 | * send it to the consoles before releasing the lock. | |
2200 | * | |
2201 | * One effect of this deferred printing is that code which calls printk() and | |
2202 | * then changes console_loglevel may break. This is because console_loglevel | |
2203 | * is inspected when the actual printing occurs. | |
2204 | * | |
2205 | * See also: | |
2206 | * printf(3) | |
2207 | * | |
2208 | * See the vsnprintf() documentation for format string extensions over C99. | |
2209 | */ | |
722a9f92 | 2210 | asmlinkage __visible int printk(const char *fmt, ...) |
7ff9554b KS |
2211 | { |
2212 | va_list args; | |
2213 | int r; | |
2214 | ||
7ff9554b | 2215 | va_start(args, fmt); |
28e1745b | 2216 | r = vprintk(fmt, args); |
7ff9554b KS |
2217 | va_end(args); |
2218 | ||
2219 | return r; | |
2220 | } | |
2221 | EXPORT_SYMBOL(printk); | |
7f3a781d | 2222 | |
96efedf1 | 2223 | #else /* CONFIG_PRINTK */ |
d59745ce | 2224 | |
cf5b0208 | 2225 | #define CONSOLE_LOG_MAX 0 |
e80c1a9d | 2226 | #define printk_time false |
249771b8 | 2227 | |
896fbe20 JO |
2228 | #define prb_read_valid(rb, seq, r) false |
2229 | #define prb_first_valid_seq(rb) 0 | |
2230 | ||
96efedf1 | 2231 | static u64 syslog_seq; |
eab07260 | 2232 | static u64 console_seq; |
f92b070f | 2233 | static u64 exclusive_console_stop_seq; |
896fbe20 JO |
2234 | static unsigned long console_dropped; |
2235 | ||
2236 | static size_t record_print_text(const struct printk_record *r, | |
2237 | bool syslog, bool time) | |
2238 | { | |
2239 | return 0; | |
2240 | } | |
2241 | static ssize_t info_print_ext_header(char *buf, size_t size, | |
2242 | struct printk_info *info) | |
2243 | { | |
2244 | return 0; | |
2245 | } | |
6fe29354 | 2246 | static ssize_t msg_print_ext_body(char *buf, size_t size, |
74caba7f JO |
2247 | char *text, size_t text_len, |
2248 | struct dev_printk_info *dev_info) { return 0; } | |
c162d5b4 PM |
2249 | static void console_lock_spinning_enable(void) { } |
2250 | static int console_lock_spinning_disable_and_check(void) { return 0; } | |
d9c23523 | 2251 | static void call_console_drivers(const char *ext_text, size_t ext_len, |
6fe29354 | 2252 | const char *text, size_t len) {} |
a6ae928c | 2253 | static bool suppress_message_printing(int level) { return false; } |
d59745ce | 2254 | |
7f3a781d | 2255 | #endif /* CONFIG_PRINTK */ |
d59745ce | 2256 | |
d0380e6c TG |
2257 | #ifdef CONFIG_EARLY_PRINTK |
2258 | struct console *early_console; | |
2259 | ||
722a9f92 | 2260 | asmlinkage __visible void early_printk(const char *fmt, ...) |
d0380e6c TG |
2261 | { |
2262 | va_list ap; | |
1dc6244b JP |
2263 | char buf[512]; |
2264 | int n; | |
2265 | ||
2266 | if (!early_console) | |
2267 | return; | |
d0380e6c TG |
2268 | |
2269 | va_start(ap, fmt); | |
1dc6244b | 2270 | n = vscnprintf(buf, sizeof(buf), fmt, ap); |
d0380e6c | 2271 | va_end(ap); |
1dc6244b JP |
2272 | |
2273 | early_console->write(early_console, buf, n); | |
d0380e6c TG |
2274 | } |
2275 | #endif | |
2276 | ||
f7511d5f | 2277 | static int __add_preferred_console(char *name, int idx, char *options, |
e369d822 | 2278 | char *brl_options, bool user_specified) |
f7511d5f ST |
2279 | { |
2280 | struct console_cmdline *c; | |
2281 | int i; | |
2282 | ||
2283 | /* | |
2284 | * See if this tty is not yet registered, and | |
2285 | * if we have a slot free. | |
2286 | */ | |
dac8bbba PM |
2287 | for (i = 0, c = console_cmdline; |
2288 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2289 | i++, c++) { | |
23475408 | 2290 | if (strcmp(c->name, name) == 0 && c->index == idx) { |
dac8bbba PM |
2291 | if (!brl_options) |
2292 | preferred_console = i; | |
e369d822 BH |
2293 | if (user_specified) |
2294 | c->user_specified = true; | |
23475408 | 2295 | return 0; |
f7511d5f | 2296 | } |
23475408 | 2297 | } |
f7511d5f ST |
2298 | if (i == MAX_CMDLINECONSOLES) |
2299 | return -E2BIG; | |
2300 | if (!brl_options) | |
ad86ee2b | 2301 | preferred_console = i; |
f7511d5f ST |
2302 | strlcpy(c->name, name, sizeof(c->name)); |
2303 | c->options = options; | |
e369d822 | 2304 | c->user_specified = user_specified; |
bbeddf52 JP |
2305 | braille_set_options(c, brl_options); |
2306 | ||
f7511d5f ST |
2307 | c->index = idx; |
2308 | return 0; | |
2309 | } | |
cca10d58 SS |
2310 | |
2311 | static int __init console_msg_format_setup(char *str) | |
2312 | { | |
2313 | if (!strcmp(str, "syslog")) | |
2314 | console_msg_format = MSG_FORMAT_SYSLOG; | |
2315 | if (!strcmp(str, "default")) | |
2316 | console_msg_format = MSG_FORMAT_DEFAULT; | |
2317 | return 1; | |
2318 | } | |
2319 | __setup("console_msg_format=", console_msg_format_setup); | |
2320 | ||
2ea1c539 | 2321 | /* |
0b90fec3 AE |
2322 | * Set up a console. Called via do_early_param() in init/main.c |
2323 | * for each "console=" parameter in the boot command line. | |
2ea1c539 JB |
2324 | */ |
2325 | static int __init console_setup(char *str) | |
2326 | { | |
0b90fec3 | 2327 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ |
f7511d5f | 2328 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
2329 | int idx; |
2330 | ||
3cffa06a PM |
2331 | /* |
2332 | * console="" or console=null have been suggested as a way to | |
2333 | * disable console output. Use ttynull that has been created | |
acebb559 | 2334 | * for exactly this purpose. |
3cffa06a PM |
2335 | */ |
2336 | if (str[0] == 0 || strcmp(str, "null") == 0) { | |
2337 | __add_preferred_console("ttynull", 0, NULL, NULL, true); | |
48021f98 | 2338 | return 1; |
3cffa06a | 2339 | } |
48021f98 | 2340 | |
bbeddf52 JP |
2341 | if (_braille_console_setup(&str, &brl_options)) |
2342 | return 1; | |
f7511d5f | 2343 | |
2ea1c539 JB |
2344 | /* |
2345 | * Decode str into name, index, options. | |
2346 | */ | |
2347 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
2348 | strcpy(buf, "ttyS"); |
2349 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 2350 | } else { |
eaa944af | 2351 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 2352 | } |
eaa944af | 2353 | buf[sizeof(buf) - 1] = 0; |
249771b8 AE |
2354 | options = strchr(str, ','); |
2355 | if (options) | |
2ea1c539 JB |
2356 | *(options++) = 0; |
2357 | #ifdef __sparc__ | |
2358 | if (!strcmp(str, "ttya")) | |
eaa944af | 2359 | strcpy(buf, "ttyS0"); |
2ea1c539 | 2360 | if (!strcmp(str, "ttyb")) |
eaa944af | 2361 | strcpy(buf, "ttyS1"); |
2ea1c539 | 2362 | #endif |
eaa944af | 2363 | for (s = buf; *s; s++) |
249771b8 | 2364 | if (isdigit(*s) || *s == ',') |
2ea1c539 JB |
2365 | break; |
2366 | idx = simple_strtoul(s, NULL, 10); | |
2367 | *s = 0; | |
2368 | ||
e369d822 | 2369 | __add_preferred_console(buf, idx, options, brl_options, true); |
9e124fe1 | 2370 | console_set_on_cmdline = 1; |
2ea1c539 JB |
2371 | return 1; |
2372 | } | |
2373 | __setup("console=", console_setup); | |
2374 | ||
3c0547ba MM |
2375 | /** |
2376 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
2377 | * @name: device name |
2378 | * @idx: device index | |
2379 | * @options: options for this console | |
3c0547ba MM |
2380 | * |
2381 | * The last preferred console added will be used for kernel messages | |
2382 | * and stdin/out/err for init. Normally this is used by console_setup | |
2383 | * above to handle user-supplied console arguments; however it can also | |
2384 | * be used by arch-specific code either to override the user or more | |
2385 | * commonly to provide a default console (ie from PROM variables) when | |
2386 | * the user has not supplied one. | |
2387 | */ | |
fb445ee5 | 2388 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 2389 | { |
e369d822 | 2390 | return __add_preferred_console(name, idx, options, NULL, false); |
3c0547ba MM |
2391 | } |
2392 | ||
d25d9fec | 2393 | bool console_suspend_enabled = true; |
8f4ce8c3 AS |
2394 | EXPORT_SYMBOL(console_suspend_enabled); |
2395 | ||
2396 | static int __init console_suspend_disable(char *str) | |
2397 | { | |
d25d9fec | 2398 | console_suspend_enabled = false; |
8f4ce8c3 AS |
2399 | return 1; |
2400 | } | |
2401 | __setup("no_console_suspend", console_suspend_disable); | |
134620f7 YZ |
2402 | module_param_named(console_suspend, console_suspend_enabled, |
2403 | bool, S_IRUGO | S_IWUSR); | |
2404 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" | |
2405 | " and hibernate operations"); | |
8f4ce8c3 | 2406 | |
557240b4 LT |
2407 | /** |
2408 | * suspend_console - suspend the console subsystem | |
2409 | * | |
2410 | * This disables printk() while we go into suspend states | |
2411 | */ | |
2412 | void suspend_console(void) | |
2413 | { | |
8f4ce8c3 AS |
2414 | if (!console_suspend_enabled) |
2415 | return; | |
47319f71 | 2416 | pr_info("Suspending console(s) (use no_console_suspend to debug)\n"); |
ac751efa | 2417 | console_lock(); |
557240b4 | 2418 | console_suspended = 1; |
bd8d7cf5 | 2419 | up_console_sem(); |
557240b4 LT |
2420 | } |
2421 | ||
2422 | void resume_console(void) | |
2423 | { | |
8f4ce8c3 AS |
2424 | if (!console_suspend_enabled) |
2425 | return; | |
bd8d7cf5 | 2426 | down_console_sem(); |
557240b4 | 2427 | console_suspended = 0; |
ac751efa | 2428 | console_unlock(); |
557240b4 LT |
2429 | } |
2430 | ||
034260d6 KC |
2431 | /** |
2432 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
90b14889 | 2433 | * @cpu: unused |
034260d6 KC |
2434 | * |
2435 | * If printk() is called from a CPU that is not online yet, the messages | |
64ca752d SS |
2436 | * will be printed on the console only if there are CON_ANYTIME consoles. |
2437 | * This function is called when a new CPU comes online (or fails to come | |
2438 | * up) or goes offline. | |
034260d6 | 2439 | */ |
90b14889 SAS |
2440 | static int console_cpu_notify(unsigned int cpu) |
2441 | { | |
f97960fb | 2442 | if (!cpuhp_tasks_frozen) { |
64ca752d SS |
2443 | /* If trylock fails, someone else is doing the printing */ |
2444 | if (console_trylock()) | |
2445 | console_unlock(); | |
034260d6 | 2446 | } |
90b14889 | 2447 | return 0; |
034260d6 KC |
2448 | } |
2449 | ||
1da177e4 | 2450 | /** |
ac751efa | 2451 | * console_lock - lock the console system for exclusive use. |
1da177e4 | 2452 | * |
ac751efa | 2453 | * Acquires a lock which guarantees that the caller has |
1da177e4 LT |
2454 | * exclusive access to the console system and the console_drivers list. |
2455 | * | |
2456 | * Can sleep, returns nothing. | |
2457 | */ | |
ac751efa | 2458 | void console_lock(void) |
1da177e4 | 2459 | { |
6b898c07 DV |
2460 | might_sleep(); |
2461 | ||
bd8d7cf5 | 2462 | down_console_sem(); |
403f3075 AH |
2463 | if (console_suspended) |
2464 | return; | |
1da177e4 LT |
2465 | console_locked = 1; |
2466 | console_may_schedule = 1; | |
2467 | } | |
ac751efa | 2468 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 2469 | |
ac751efa TH |
2470 | /** |
2471 | * console_trylock - try to lock the console system for exclusive use. | |
2472 | * | |
0b90fec3 AE |
2473 | * Try to acquire a lock which guarantees that the caller has exclusive |
2474 | * access to the console system and the console_drivers list. | |
ac751efa TH |
2475 | * |
2476 | * returns 1 on success, and 0 on failure to acquire the lock. | |
2477 | */ | |
2478 | int console_trylock(void) | |
1da177e4 | 2479 | { |
bd8d7cf5 | 2480 | if (down_trylock_console_sem()) |
ac751efa | 2481 | return 0; |
403f3075 | 2482 | if (console_suspended) { |
bd8d7cf5 | 2483 | up_console_sem(); |
ac751efa | 2484 | return 0; |
403f3075 | 2485 | } |
1da177e4 | 2486 | console_locked = 1; |
fd5f7cde | 2487 | console_may_schedule = 0; |
ac751efa | 2488 | return 1; |
1da177e4 | 2489 | } |
ac751efa | 2490 | EXPORT_SYMBOL(console_trylock); |
1da177e4 LT |
2491 | |
2492 | int is_console_locked(void) | |
2493 | { | |
2494 | return console_locked; | |
2495 | } | |
d48de54a | 2496 | EXPORT_SYMBOL(is_console_locked); |
1da177e4 | 2497 | |
a8199371 SS |
2498 | /* |
2499 | * Check if we have any console that is capable of printing while cpu is | |
2500 | * booting or shutting down. Requires console_sem. | |
2501 | */ | |
2502 | static int have_callable_console(void) | |
2503 | { | |
2504 | struct console *con; | |
2505 | ||
2506 | for_each_console(con) | |
adaf6590 SS |
2507 | if ((con->flags & CON_ENABLED) && |
2508 | (con->flags & CON_ANYTIME)) | |
a8199371 SS |
2509 | return 1; |
2510 | ||
2511 | return 0; | |
2512 | } | |
2513 | ||
2514 | /* | |
2515 | * Can we actually use the console at this time on this cpu? | |
2516 | * | |
2517 | * Console drivers may assume that per-cpu resources have been allocated. So | |
2518 | * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't | |
2519 | * call them until this CPU is officially up. | |
2520 | */ | |
2521 | static inline int can_use_console(void) | |
2522 | { | |
2523 | return cpu_online(raw_smp_processor_id()) || have_callable_console(); | |
2524 | } | |
2525 | ||
1da177e4 | 2526 | /** |
ac751efa | 2527 | * console_unlock - unlock the console system |
1da177e4 | 2528 | * |
ac751efa | 2529 | * Releases the console_lock which the caller holds on the console system |
1da177e4 LT |
2530 | * and the console driver list. |
2531 | * | |
ac751efa TH |
2532 | * While the console_lock was held, console output may have been buffered |
2533 | * by printk(). If this is the case, console_unlock(); emits | |
2534 | * the output prior to releasing the lock. | |
1da177e4 | 2535 | * |
7f3a781d | 2536 | * If there is output waiting, we wake /dev/kmsg and syslog() users. |
1da177e4 | 2537 | * |
ac751efa | 2538 | * console_unlock(); may be called from any context. |
1da177e4 | 2539 | */ |
ac751efa | 2540 | void console_unlock(void) |
1da177e4 | 2541 | { |
6fe29354 | 2542 | static char ext_text[CONSOLE_EXT_LOG_MAX]; |
cf5b0208 | 2543 | static char text[CONSOLE_LOG_MAX]; |
1da177e4 | 2544 | unsigned long flags; |
8d91f8b1 | 2545 | bool do_cond_resched, retry; |
896fbe20 JO |
2546 | struct printk_info info; |
2547 | struct printk_record r; | |
1da177e4 | 2548 | |
557240b4 | 2549 | if (console_suspended) { |
bd8d7cf5 | 2550 | up_console_sem(); |
557240b4 LT |
2551 | return; |
2552 | } | |
78944e54 | 2553 | |
f35efc78 | 2554 | prb_rec_init_rd(&r, &info, text, sizeof(text)); |
896fbe20 | 2555 | |
8d91f8b1 | 2556 | /* |
257ab443 | 2557 | * Console drivers are called with interrupts disabled, so |
8d91f8b1 TH |
2558 | * @console_may_schedule should be cleared before; however, we may |
2559 | * end up dumping a lot of lines, for example, if called from | |
2560 | * console registration path, and should invoke cond_resched() | |
2561 | * between lines if allowable. Not doing so can cause a very long | |
2562 | * scheduling stall on a slow console leading to RCU stall and | |
2563 | * softlockup warnings which exacerbate the issue with more | |
2564 | * messages practically incapacitating the system. | |
257ab443 PM |
2565 | * |
2566 | * console_trylock() is not able to detect the preemptive | |
2567 | * context reliably. Therefore the value must be stored before | |
547bbf7d | 2568 | * and cleared after the "again" goto label. |
8d91f8b1 TH |
2569 | */ |
2570 | do_cond_resched = console_may_schedule; | |
257ab443 | 2571 | again: |
78944e54 AD |
2572 | console_may_schedule = 0; |
2573 | ||
a8199371 SS |
2574 | /* |
2575 | * We released the console_sem lock, so we need to recheck if | |
2576 | * cpu is online and (if not) is there at least one CON_ANYTIME | |
2577 | * console. | |
2578 | */ | |
2579 | if (!can_use_console()) { | |
2580 | console_locked = 0; | |
2581 | up_console_sem(); | |
2582 | return; | |
2583 | } | |
2584 | ||
7ff9554b | 2585 | for (;;) { |
6fe29354 | 2586 | size_t ext_len = 0; |
3ce9a7c0 | 2587 | size_t len; |
7ff9554b | 2588 | |
f975237b | 2589 | printk_safe_enter_irqsave(flags); |
084681d1 | 2590 | skip: |
896fbe20 | 2591 | if (!prb_read_valid(prb, console_seq, &r)) |
7ff9554b KS |
2592 | break; |
2593 | ||
896fbe20 JO |
2594 | if (console_seq != r.info->seq) { |
2595 | console_dropped += r.info->seq - console_seq; | |
2596 | console_seq = r.info->seq; | |
2597 | } | |
2598 | ||
2599 | if (suppress_message_printing(r.info->level)) { | |
084681d1 | 2600 | /* |
a6ae928c PM |
2601 | * Skip record we have buffered and already printed |
2602 | * directly to the console when we received it, and | |
2603 | * record that has level above the console loglevel. | |
084681d1 | 2604 | */ |
084681d1 KS |
2605 | console_seq++; |
2606 | goto skip; | |
2607 | } | |
649e6ee3 | 2608 | |
f92b070f PM |
2609 | /* Output to all consoles once old messages replayed. */ |
2610 | if (unlikely(exclusive_console && | |
2611 | console_seq >= exclusive_console_stop_seq)) { | |
2612 | exclusive_console = NULL; | |
2613 | } | |
2614 | ||
896fbe20 JO |
2615 | /* |
2616 | * Handle extended console text first because later | |
2617 | * record_print_text() will modify the record buffer in-place. | |
2618 | */ | |
6fe29354 | 2619 | if (nr_ext_console_drivers) { |
896fbe20 | 2620 | ext_len = info_print_ext_header(ext_text, |
6fe29354 | 2621 | sizeof(ext_text), |
896fbe20 | 2622 | r.info); |
6fe29354 TH |
2623 | ext_len += msg_print_ext_body(ext_text + ext_len, |
2624 | sizeof(ext_text) - ext_len, | |
896fbe20 | 2625 | &r.text_buf[0], |
74caba7f JO |
2626 | r.info->text_len, |
2627 | &r.info->dev_info); | |
6fe29354 | 2628 | } |
896fbe20 JO |
2629 | len = record_print_text(&r, |
2630 | console_msg_format & MSG_FORMAT_SYSLOG, | |
2631 | printk_time); | |
7ff9554b | 2632 | console_seq++; |
7ff9554b | 2633 | |
dbdda842 SRV |
2634 | /* |
2635 | * While actively printing out messages, if another printk() | |
2636 | * were to occur on another CPU, it may wait for this one to | |
2637 | * finish. This task can not be preempted if there is a | |
2638 | * waiter waiting to take over. | |
2639 | */ | |
c162d5b4 | 2640 | console_lock_spinning_enable(); |
dbdda842 | 2641 | |
81d68a96 | 2642 | stop_critical_timings(); /* don't trace print latency */ |
d9c23523 | 2643 | call_console_drivers(ext_text, ext_len, text, len); |
81d68a96 | 2644 | start_critical_timings(); |
dbdda842 | 2645 | |
c162d5b4 PM |
2646 | if (console_lock_spinning_disable_and_check()) { |
2647 | printk_safe_exit_irqrestore(flags); | |
43a17111 | 2648 | return; |
c162d5b4 | 2649 | } |
dbdda842 | 2650 | |
f975237b | 2651 | printk_safe_exit_irqrestore(flags); |
8d91f8b1 TH |
2652 | |
2653 | if (do_cond_resched) | |
2654 | cond_resched(); | |
1da177e4 | 2655 | } |
dbdda842 | 2656 | |
1da177e4 | 2657 | console_locked = 0; |
fe3d8ad3 | 2658 | |
bd8d7cf5 | 2659 | up_console_sem(); |
4f2a8d3c PZ |
2660 | |
2661 | /* | |
2662 | * Someone could have filled up the buffer again, so re-check if there's | |
2663 | * something to flush. In case we cannot trylock the console_sem again, | |
2664 | * there's a new owner and the console_unlock() from them will do the | |
2665 | * flush, no worries. | |
2666 | */ | |
896fbe20 | 2667 | retry = prb_read_valid(prb, console_seq, NULL); |
f975237b | 2668 | printk_safe_exit_irqrestore(flags); |
09dc3cf9 | 2669 | |
4f2a8d3c PZ |
2670 | if (retry && console_trylock()) |
2671 | goto again; | |
1da177e4 | 2672 | } |
ac751efa | 2673 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 2674 | |
ddad86c2 MW |
2675 | /** |
2676 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
2677 | * |
2678 | * If the console code is currently allowed to sleep, and | |
2679 | * if this CPU should yield the CPU to another task, do | |
2680 | * so here. | |
2681 | * | |
ac751efa | 2682 | * Must be called within console_lock();. |
1da177e4 LT |
2683 | */ |
2684 | void __sched console_conditional_schedule(void) | |
2685 | { | |
2686 | if (console_may_schedule) | |
2687 | cond_resched(); | |
2688 | } | |
2689 | EXPORT_SYMBOL(console_conditional_schedule); | |
2690 | ||
1da177e4 LT |
2691 | void console_unblank(void) |
2692 | { | |
2693 | struct console *c; | |
2694 | ||
2695 | /* | |
2696 | * console_unblank can no longer be called in interrupt context unless | |
2697 | * oops_in_progress is set to 1.. | |
2698 | */ | |
2699 | if (oops_in_progress) { | |
bd8d7cf5 | 2700 | if (down_trylock_console_sem() != 0) |
1da177e4 LT |
2701 | return; |
2702 | } else | |
ac751efa | 2703 | console_lock(); |
1da177e4 LT |
2704 | |
2705 | console_locked = 1; | |
2706 | console_may_schedule = 0; | |
4d091611 | 2707 | for_each_console(c) |
1da177e4 LT |
2708 | if ((c->flags & CON_ENABLED) && c->unblank) |
2709 | c->unblank(); | |
ac751efa | 2710 | console_unlock(); |
1da177e4 | 2711 | } |
1da177e4 | 2712 | |
8d91f8b1 TH |
2713 | /** |
2714 | * console_flush_on_panic - flush console content on panic | |
de6da1e8 | 2715 | * @mode: flush all messages in buffer or just the pending ones |
8d91f8b1 TH |
2716 | * |
2717 | * Immediately output all pending messages no matter what. | |
2718 | */ | |
de6da1e8 | 2719 | void console_flush_on_panic(enum con_flush_mode mode) |
8d91f8b1 TH |
2720 | { |
2721 | /* | |
2722 | * If someone else is holding the console lock, trylock will fail | |
2723 | * and may_schedule may be set. Ignore and proceed to unlock so | |
2724 | * that messages are flushed out. As this can be called from any | |
2725 | * context and we don't want to get preempted while flushing, | |
2726 | * ensure may_schedule is cleared. | |
2727 | */ | |
2728 | console_trylock(); | |
2729 | console_may_schedule = 0; | |
de6da1e8 FT |
2730 | |
2731 | if (mode == CONSOLE_REPLAY_ALL) { | |
2732 | unsigned long flags; | |
2733 | ||
996e9666 | 2734 | printk_safe_enter_irqsave(flags); |
896fbe20 | 2735 | console_seq = prb_first_valid_seq(prb); |
996e9666 | 2736 | printk_safe_exit_irqrestore(flags); |
de6da1e8 | 2737 | } |
8d91f8b1 TH |
2738 | console_unlock(); |
2739 | } | |
2740 | ||
1da177e4 LT |
2741 | /* |
2742 | * Return the console tty driver structure and its associated index | |
2743 | */ | |
2744 | struct tty_driver *console_device(int *index) | |
2745 | { | |
2746 | struct console *c; | |
2747 | struct tty_driver *driver = NULL; | |
2748 | ||
ac751efa | 2749 | console_lock(); |
4d091611 | 2750 | for_each_console(c) { |
1da177e4 LT |
2751 | if (!c->device) |
2752 | continue; | |
2753 | driver = c->device(c, index); | |
2754 | if (driver) | |
2755 | break; | |
2756 | } | |
ac751efa | 2757 | console_unlock(); |
1da177e4 LT |
2758 | return driver; |
2759 | } | |
2760 | ||
2761 | /* | |
2762 | * Prevent further output on the passed console device so that (for example) | |
2763 | * serial drivers can disable console output before suspending a port, and can | |
2764 | * re-enable output afterwards. | |
2765 | */ | |
2766 | void console_stop(struct console *console) | |
2767 | { | |
ac751efa | 2768 | console_lock(); |
1da177e4 | 2769 | console->flags &= ~CON_ENABLED; |
ac751efa | 2770 | console_unlock(); |
1da177e4 LT |
2771 | } |
2772 | EXPORT_SYMBOL(console_stop); | |
2773 | ||
2774 | void console_start(struct console *console) | |
2775 | { | |
ac751efa | 2776 | console_lock(); |
1da177e4 | 2777 | console->flags |= CON_ENABLED; |
ac751efa | 2778 | console_unlock(); |
1da177e4 LT |
2779 | } |
2780 | EXPORT_SYMBOL(console_start); | |
2781 | ||
7bf69395 FDN |
2782 | static int __read_mostly keep_bootcon; |
2783 | ||
2784 | static int __init keep_bootcon_setup(char *str) | |
2785 | { | |
2786 | keep_bootcon = 1; | |
27083bac | 2787 | pr_info("debug: skip boot console de-registration.\n"); |
7bf69395 FDN |
2788 | |
2789 | return 0; | |
2790 | } | |
2791 | ||
2792 | early_param("keep_bootcon", keep_bootcon_setup); | |
2793 | ||
ad8cd1db BH |
2794 | /* |
2795 | * This is called by register_console() to try to match | |
2796 | * the newly registered console with any of the ones selected | |
2797 | * by either the command line or add_preferred_console() and | |
2798 | * setup/enable it. | |
2799 | * | |
2800 | * Care need to be taken with consoles that are statically | |
2801 | * enabled such as netconsole | |
2802 | */ | |
e369d822 | 2803 | static int try_enable_new_console(struct console *newcon, bool user_specified) |
ad8cd1db BH |
2804 | { |
2805 | struct console_cmdline *c; | |
bba18a1a | 2806 | int i, err; |
ad8cd1db BH |
2807 | |
2808 | for (i = 0, c = console_cmdline; | |
2809 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2810 | i++, c++) { | |
e369d822 BH |
2811 | if (c->user_specified != user_specified) |
2812 | continue; | |
ad8cd1db BH |
2813 | if (!newcon->match || |
2814 | newcon->match(newcon, c->name, c->index, c->options) != 0) { | |
2815 | /* default matching */ | |
2816 | BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name)); | |
2817 | if (strcmp(c->name, newcon->name) != 0) | |
2818 | continue; | |
2819 | if (newcon->index >= 0 && | |
2820 | newcon->index != c->index) | |
2821 | continue; | |
2822 | if (newcon->index < 0) | |
2823 | newcon->index = c->index; | |
2824 | ||
2825 | if (_braille_register_console(newcon, c)) | |
2826 | return 0; | |
2827 | ||
2828 | if (newcon->setup && | |
bba18a1a AS |
2829 | (err = newcon->setup(newcon, c->options)) != 0) |
2830 | return err; | |
ad8cd1db BH |
2831 | } |
2832 | newcon->flags |= CON_ENABLED; | |
2833 | if (i == preferred_console) { | |
2834 | newcon->flags |= CON_CONSDEV; | |
2835 | has_preferred_console = true; | |
2836 | } | |
2837 | return 0; | |
2838 | } | |
2839 | ||
2840 | /* | |
2841 | * Some consoles, such as pstore and netconsole, can be enabled even | |
e369d822 | 2842 | * without matching. Accept the pre-enabled consoles only when match() |
50460376 | 2843 | * and setup() had a chance to be called. |
ad8cd1db | 2844 | */ |
e369d822 | 2845 | if (newcon->flags & CON_ENABLED && c->user_specified == user_specified) |
ad8cd1db BH |
2846 | return 0; |
2847 | ||
2848 | return -ENOENT; | |
2849 | } | |
2850 | ||
1da177e4 LT |
2851 | /* |
2852 | * The console driver calls this routine during kernel initialization | |
2853 | * to register the console printing procedure with printk() and to | |
2854 | * print any messages that were printed by the kernel before the | |
2855 | * console driver was initialized. | |
4d091611 RG |
2856 | * |
2857 | * This can happen pretty early during the boot process (because of | |
2858 | * early_printk) - sometimes before setup_arch() completes - be careful | |
2859 | * of what kernel features are used - they may not be initialised yet. | |
2860 | * | |
2861 | * There are two types of consoles - bootconsoles (early_printk) and | |
2862 | * "real" consoles (everything which is not a bootconsole) which are | |
2863 | * handled differently. | |
2864 | * - Any number of bootconsoles can be registered at any time. | |
2865 | * - As soon as a "real" console is registered, all bootconsoles | |
2866 | * will be unregistered automatically. | |
2867 | * - Once a "real" console is registered, any attempt to register a | |
2868 | * bootconsoles will be rejected | |
1da177e4 | 2869 | */ |
4d091611 | 2870 | void register_console(struct console *newcon) |
1da177e4 | 2871 | { |
1da177e4 | 2872 | unsigned long flags; |
4d091611 | 2873 | struct console *bcon = NULL; |
ad8cd1db | 2874 | int err; |
1da177e4 | 2875 | |
caa72c3b AS |
2876 | for_each_console(bcon) { |
2877 | if (WARN(bcon == newcon, "console '%s%d' already registered\n", | |
2878 | bcon->name, bcon->index)) | |
2879 | return; | |
2880 | } | |
16cf48a6 | 2881 | |
4d091611 RG |
2882 | /* |
2883 | * before we register a new CON_BOOT console, make sure we don't | |
2884 | * already have a valid console | |
2885 | */ | |
caa72c3b | 2886 | if (newcon->flags & CON_BOOT) { |
4d091611 RG |
2887 | for_each_console(bcon) { |
2888 | if (!(bcon->flags & CON_BOOT)) { | |
27083bac | 2889 | pr_info("Too late to register bootconsole %s%d\n", |
4d091611 RG |
2890 | newcon->name, newcon->index); |
2891 | return; | |
2892 | } | |
2893 | } | |
69331af7 GH |
2894 | } |
2895 | ||
4d091611 RG |
2896 | if (console_drivers && console_drivers->flags & CON_BOOT) |
2897 | bcon = console_drivers; | |
2898 | ||
ad8cd1db BH |
2899 | if (!has_preferred_console || bcon || !console_drivers) |
2900 | has_preferred_console = preferred_console >= 0; | |
1da177e4 LT |
2901 | |
2902 | /* | |
2903 | * See if we want to use this console driver. If we | |
2904 | * didn't select a console we take the first one | |
2905 | * that registers here. | |
2906 | */ | |
ad8cd1db | 2907 | if (!has_preferred_console) { |
4d091611 RG |
2908 | if (newcon->index < 0) |
2909 | newcon->index = 0; | |
2910 | if (newcon->setup == NULL || | |
2911 | newcon->setup(newcon, NULL) == 0) { | |
2912 | newcon->flags |= CON_ENABLED; | |
2913 | if (newcon->device) { | |
2914 | newcon->flags |= CON_CONSDEV; | |
ad8cd1db | 2915 | has_preferred_console = true; |
cd3a1b85 | 2916 | } |
1da177e4 LT |
2917 | } |
2918 | } | |
2919 | ||
e369d822 BH |
2920 | /* See if this console matches one we selected on the command line */ |
2921 | err = try_enable_new_console(newcon, true); | |
bbeddf52 | 2922 | |
e369d822 BH |
2923 | /* If not, try to match against the platform default(s) */ |
2924 | if (err == -ENOENT) | |
2925 | err = try_enable_new_console(newcon, false); | |
1da177e4 | 2926 | |
ad8cd1db BH |
2927 | /* printk() messages are not printed to the Braille console. */ |
2928 | if (err || newcon->flags & CON_BRL) | |
1da177e4 LT |
2929 | return; |
2930 | ||
8259cf43 RG |
2931 | /* |
2932 | * If we have a bootconsole, and are switching to a real console, | |
2933 | * don't print everything out again, since when the boot console, and | |
2934 | * the real console are the same physical device, it's annoying to | |
2935 | * see the beginning boot messages twice | |
2936 | */ | |
2937 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 2938 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
2939 | |
2940 | /* | |
2941 | * Put this console in the list - keep the | |
2942 | * preferred driver at the head of the list. | |
2943 | */ | |
ac751efa | 2944 | console_lock(); |
4d091611 RG |
2945 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
2946 | newcon->next = console_drivers; | |
2947 | console_drivers = newcon; | |
2948 | if (newcon->next) | |
2949 | newcon->next->flags &= ~CON_CONSDEV; | |
33225d7b BH |
2950 | /* Ensure this flag is always set for the head of the list */ |
2951 | newcon->flags |= CON_CONSDEV; | |
1da177e4 | 2952 | } else { |
4d091611 RG |
2953 | newcon->next = console_drivers->next; |
2954 | console_drivers->next = newcon; | |
1da177e4 | 2955 | } |
6fe29354 TH |
2956 | |
2957 | if (newcon->flags & CON_EXTENDED) | |
9627808d | 2958 | nr_ext_console_drivers++; |
6fe29354 | 2959 | |
4d091611 | 2960 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 | 2961 | /* |
ac751efa | 2962 | * console_unlock(); will print out the buffered messages |
1da177e4 | 2963 | * for us. |
505a27a7 | 2964 | * |
fe3d8ad3 FT |
2965 | * We're about to replay the log buffer. Only do this to the |
2966 | * just-registered console to avoid excessive message spam to | |
2967 | * the already-registered consoles. | |
884e370e SS |
2968 | * |
2969 | * Set exclusive_console with disabled interrupts to reduce | |
2970 | * race window with eventual console_flush_on_panic() that | |
2971 | * ignores console_lock. | |
fe3d8ad3 FT |
2972 | */ |
2973 | exclusive_console = newcon; | |
f92b070f | 2974 | exclusive_console_stop_seq = console_seq; |
636babdc JO |
2975 | |
2976 | /* Get a consistent copy of @syslog_seq. */ | |
505a27a7 | 2977 | raw_spin_lock_irqsave(&syslog_lock, flags); |
def97da1 | 2978 | console_seq = syslog_seq; |
505a27a7 | 2979 | raw_spin_unlock_irqrestore(&syslog_lock, flags); |
1da177e4 | 2980 | } |
ac751efa | 2981 | console_unlock(); |
fbc92a34 | 2982 | console_sysfs_notify(); |
8259cf43 RG |
2983 | |
2984 | /* | |
2985 | * By unregistering the bootconsoles after we enable the real console | |
2986 | * we get the "console xxx enabled" message on all the consoles - | |
2987 | * boot consoles, real consoles, etc - this is to ensure that end | |
2988 | * users know there might be something in the kernel's log buffer that | |
2989 | * went to the bootconsole (that they do not see on the real console) | |
2990 | */ | |
27083bac | 2991 | pr_info("%sconsole [%s%d] enabled\n", |
6b802394 KC |
2992 | (newcon->flags & CON_BOOT) ? "boot" : "" , |
2993 | newcon->name, newcon->index); | |
7bf69395 FDN |
2994 | if (bcon && |
2995 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && | |
2996 | !keep_bootcon) { | |
6b802394 KC |
2997 | /* We need to iterate through all boot consoles, to make |
2998 | * sure we print everything out, before we unregister them. | |
8259cf43 | 2999 | */ |
8259cf43 RG |
3000 | for_each_console(bcon) |
3001 | if (bcon->flags & CON_BOOT) | |
3002 | unregister_console(bcon); | |
8259cf43 | 3003 | } |
1da177e4 LT |
3004 | } |
3005 | EXPORT_SYMBOL(register_console); | |
3006 | ||
40dc5651 | 3007 | int unregister_console(struct console *console) |
1da177e4 | 3008 | { |
12825e6b | 3009 | struct console *con; |
bbeddf52 | 3010 | int res; |
1da177e4 | 3011 | |
27083bac | 3012 | pr_info("%sconsole [%s%d] disabled\n", |
6b802394 KC |
3013 | (console->flags & CON_BOOT) ? "boot" : "" , |
3014 | console->name, console->index); | |
3015 | ||
bbeddf52 | 3016 | res = _braille_unregister_console(console); |
bb72e398 | 3017 | if (res < 0) |
bbeddf52 | 3018 | return res; |
bb72e398 AS |
3019 | if (res > 0) |
3020 | return 0; | |
f7511d5f | 3021 | |
bb72e398 | 3022 | res = -ENODEV; |
ac751efa | 3023 | console_lock(); |
1da177e4 LT |
3024 | if (console_drivers == console) { |
3025 | console_drivers=console->next; | |
3026 | res = 0; | |
12825e6b AS |
3027 | } else { |
3028 | for_each_console(con) { | |
3029 | if (con->next == console) { | |
3030 | con->next = console->next; | |
1da177e4 LT |
3031 | res = 0; |
3032 | break; | |
40dc5651 | 3033 | } |
1da177e4 LT |
3034 | } |
3035 | } | |
40dc5651 | 3036 | |
e78bedbd AS |
3037 | if (res) |
3038 | goto out_disable_unlock; | |
3039 | ||
3040 | if (console->flags & CON_EXTENDED) | |
6fe29354 TH |
3041 | nr_ext_console_drivers--; |
3042 | ||
69331af7 | 3043 | /* |
ab4af03a GE |
3044 | * If this isn't the last console and it has CON_CONSDEV set, we |
3045 | * need to set it on the next preferred console. | |
1da177e4 | 3046 | */ |
69331af7 | 3047 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 3048 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 | 3049 | |
7fa21dd8 | 3050 | console->flags &= ~CON_ENABLED; |
ac751efa | 3051 | console_unlock(); |
fbc92a34 | 3052 | console_sysfs_notify(); |
e78bedbd | 3053 | |
ed31685c AS |
3054 | if (console->exit) |
3055 | res = console->exit(console); | |
3056 | ||
e78bedbd AS |
3057 | return res; |
3058 | ||
3059 | out_disable_unlock: | |
3060 | console->flags &= ~CON_ENABLED; | |
3061 | console_unlock(); | |
3062 | ||
1da177e4 LT |
3063 | return res; |
3064 | } | |
3065 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 3066 | |
0c688614 NP |
3067 | /* |
3068 | * Initialize the console device. This is called *early*, so | |
3069 | * we can't necessarily depend on lots of kernel help here. | |
3070 | * Just do some early initializations, and do the complex setup | |
3071 | * later. | |
3072 | */ | |
3073 | void __init console_init(void) | |
3074 | { | |
58eacfff | 3075 | int ret; |
1b1eeca7 AB |
3076 | initcall_t call; |
3077 | initcall_entry_t *ce; | |
0c688614 NP |
3078 | |
3079 | /* Setup the default TTY line discipline. */ | |
3080 | n_tty_init(); | |
3081 | ||
3082 | /* | |
3083 | * set up the console device so that later boot sequences can | |
3084 | * inform about problems etc.. | |
3085 | */ | |
1b1eeca7 | 3086 | ce = __con_initcall_start; |
58eacfff | 3087 | trace_initcall_level("console"); |
1b1eeca7 AB |
3088 | while (ce < __con_initcall_end) { |
3089 | call = initcall_from_entry(ce); | |
3090 | trace_initcall_start(call); | |
3091 | ret = call(); | |
3092 | trace_initcall_finish(call, ret); | |
3093 | ce++; | |
0c688614 NP |
3094 | } |
3095 | } | |
3096 | ||
81cc26f2 TR |
3097 | /* |
3098 | * Some boot consoles access data that is in the init section and which will | |
3099 | * be discarded after the initcalls have been run. To make sure that no code | |
3100 | * will access this data, unregister the boot consoles in a late initcall. | |
3101 | * | |
3102 | * If for some reason, such as deferred probe or the driver being a loadable | |
3103 | * module, the real console hasn't registered yet at this point, there will | |
3104 | * be a brief interval in which no messages are logged to the console, which | |
3105 | * makes it difficult to diagnose problems that occur during this time. | |
3106 | * | |
3107 | * To mitigate this problem somewhat, only unregister consoles whose memory | |
2b1be689 | 3108 | * intersects with the init section. Note that all other boot consoles will |
acebb559 | 3109 | * get unregistered when the real preferred console is registered. |
81cc26f2 | 3110 | */ |
034260d6 | 3111 | static int __init printk_late_init(void) |
0c5564bd | 3112 | { |
4d091611 | 3113 | struct console *con; |
90b14889 | 3114 | int ret; |
4d091611 RG |
3115 | |
3116 | for_each_console(con) { | |
5a814231 PM |
3117 | if (!(con->flags & CON_BOOT)) |
3118 | continue; | |
3119 | ||
3120 | /* Check addresses that might be used for enabled consoles. */ | |
3121 | if (init_section_intersects(con, sizeof(*con)) || | |
3122 | init_section_contains(con->write, 0) || | |
3123 | init_section_contains(con->read, 0) || | |
3124 | init_section_contains(con->device, 0) || | |
3125 | init_section_contains(con->unblank, 0) || | |
3126 | init_section_contains(con->data, 0)) { | |
81cc26f2 | 3127 | /* |
2b1be689 MR |
3128 | * Please, consider moving the reported consoles out |
3129 | * of the init section. | |
81cc26f2 | 3130 | */ |
2b1be689 MR |
3131 | pr_warn("bootconsole [%s%d] uses init memory and must be disabled even before the real one is ready\n", |
3132 | con->name, con->index); | |
3133 | unregister_console(con); | |
cb00e99c | 3134 | } |
0c5564bd | 3135 | } |
90b14889 SAS |
3136 | ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL, |
3137 | console_cpu_notify); | |
3138 | WARN_ON(ret < 0); | |
3139 | ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "printk:online", | |
3140 | console_cpu_notify, NULL); | |
3141 | WARN_ON(ret < 0); | |
0c5564bd RG |
3142 | return 0; |
3143 | } | |
034260d6 | 3144 | late_initcall(printk_late_init); |
0c5564bd | 3145 | |
7ef3d2fd | 3146 | #if defined CONFIG_PRINTK |
dc72c32e FW |
3147 | /* |
3148 | * Delayed printk version, for scheduler-internal messages: | |
3149 | */ | |
dc72c32e | 3150 | #define PRINTK_PENDING_WAKEUP 0x01 |
458df9fd | 3151 | #define PRINTK_PENDING_OUTPUT 0x02 |
dc72c32e FW |
3152 | |
3153 | static DEFINE_PER_CPU(int, printk_pending); | |
dc72c32e FW |
3154 | |
3155 | static void wake_up_klogd_work_func(struct irq_work *irq_work) | |
3156 | { | |
3157 | int pending = __this_cpu_xchg(printk_pending, 0); | |
3158 | ||
458df9fd SR |
3159 | if (pending & PRINTK_PENDING_OUTPUT) { |
3160 | /* If trylock fails, someone else is doing the printing */ | |
3161 | if (console_trylock()) | |
3162 | console_unlock(); | |
dc72c32e FW |
3163 | } |
3164 | ||
3165 | if (pending & PRINTK_PENDING_WAKEUP) | |
3166 | wake_up_interruptible(&log_wait); | |
3167 | } | |
3168 | ||
7a9f50a0 PZ |
3169 | static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = |
3170 | IRQ_WORK_INIT_LAZY(wake_up_klogd_work_func); | |
dc72c32e FW |
3171 | |
3172 | void wake_up_klogd(void) | |
3173 | { | |
ab6f762f SS |
3174 | if (!printk_percpu_data_ready()) |
3175 | return; | |
3176 | ||
dc72c32e FW |
3177 | preempt_disable(); |
3178 | if (waitqueue_active(&log_wait)) { | |
3179 | this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); | |
bb964a92 | 3180 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
dc72c32e FW |
3181 | } |
3182 | preempt_enable(); | |
3183 | } | |
717115e1 | 3184 | |
a338f84d | 3185 | void defer_console_output(void) |
600e1458 | 3186 | { |
ab6f762f SS |
3187 | if (!printk_percpu_data_ready()) |
3188 | return; | |
3189 | ||
719f6a70 | 3190 | preempt_disable(); |
458df9fd | 3191 | __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); |
bb964a92 | 3192 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
81954606 | 3193 | preempt_enable(); |
a338f84d PM |
3194 | } |
3195 | ||
3196 | int vprintk_deferred(const char *fmt, va_list args) | |
3197 | { | |
3198 | int r; | |
3199 | ||
74caba7f | 3200 | r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, fmt, args); |
a338f84d | 3201 | defer_console_output(); |
600e1458 PZ |
3202 | |
3203 | return r; | |
3204 | } | |
3205 | ||
719f6a70 PM |
3206 | int printk_deferred(const char *fmt, ...) |
3207 | { | |
3208 | va_list args; | |
3209 | int r; | |
3210 | ||
3211 | va_start(args, fmt); | |
3212 | r = vprintk_deferred(fmt, args); | |
3213 | va_end(args); | |
3214 | ||
3215 | return r; | |
3216 | } | |
3217 | ||
1da177e4 LT |
3218 | /* |
3219 | * printk rate limiting, lifted from the networking subsystem. | |
3220 | * | |
641de9d8 UKK |
3221 | * This enforces a rate limit: not more than 10 kernel messages |
3222 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 3223 | */ |
641de9d8 UKK |
3224 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
3225 | ||
5c828713 | 3226 | int __printk_ratelimit(const char *func) |
1da177e4 | 3227 | { |
5c828713 | 3228 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 3229 | } |
5c828713 | 3230 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
3231 | |
3232 | /** | |
3233 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
3234 | * @caller_jiffies: pointer to caller's state | |
3235 | * @interval_msecs: minimum interval between prints | |
3236 | * | |
3237 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
3238 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
3239 | * returned true. | |
3240 | */ | |
3241 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
3242 | unsigned int interval_msecs) | |
3243 | { | |
249771b8 AE |
3244 | unsigned long elapsed = jiffies - *caller_jiffies; |
3245 | ||
3246 | if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) | |
3247 | return false; | |
3248 | ||
3249 | *caller_jiffies = jiffies; | |
3250 | return true; | |
f46c4833 AM |
3251 | } |
3252 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
3253 | |
3254 | static DEFINE_SPINLOCK(dump_list_lock); | |
3255 | static LIST_HEAD(dump_list); | |
3256 | ||
3257 | /** | |
3258 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 3259 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
3260 | * |
3261 | * Adds a kernel log dumper to the system. The dump callback in the | |
3262 | * structure will be called when the kernel oopses or panics and must be | |
3263 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
3264 | */ | |
3265 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
3266 | { | |
3267 | unsigned long flags; | |
3268 | int err = -EBUSY; | |
3269 | ||
3270 | /* The dump callback needs to be set */ | |
3271 | if (!dumper->dump) | |
3272 | return -EINVAL; | |
3273 | ||
3274 | spin_lock_irqsave(&dump_list_lock, flags); | |
3275 | /* Don't allow registering multiple times */ | |
3276 | if (!dumper->registered) { | |
3277 | dumper->registered = 1; | |
fb842b00 | 3278 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
3279 | err = 0; |
3280 | } | |
3281 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
3282 | ||
3283 | return err; | |
3284 | } | |
3285 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
3286 | ||
3287 | /** | |
3288 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 3289 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
3290 | * |
3291 | * Removes a dump device from the system. Returns zero on success and | |
3292 | * %-EINVAL otherwise. | |
3293 | */ | |
3294 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
3295 | { | |
3296 | unsigned long flags; | |
3297 | int err = -EINVAL; | |
3298 | ||
3299 | spin_lock_irqsave(&dump_list_lock, flags); | |
3300 | if (dumper->registered) { | |
3301 | dumper->registered = 0; | |
fb842b00 | 3302 | list_del_rcu(&dumper->list); |
456b565c SK |
3303 | err = 0; |
3304 | } | |
3305 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 3306 | synchronize_rcu(); |
456b565c SK |
3307 | |
3308 | return err; | |
3309 | } | |
3310 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
3311 | ||
7ff9554b KS |
3312 | static bool always_kmsg_dump; |
3313 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); | |
3314 | ||
fb13cb8a KC |
3315 | const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason) |
3316 | { | |
3317 | switch (reason) { | |
3318 | case KMSG_DUMP_PANIC: | |
3319 | return "Panic"; | |
3320 | case KMSG_DUMP_OOPS: | |
3321 | return "Oops"; | |
3322 | case KMSG_DUMP_EMERG: | |
3323 | return "Emergency"; | |
3324 | case KMSG_DUMP_SHUTDOWN: | |
3325 | return "Shutdown"; | |
3326 | default: | |
3327 | return "Unknown"; | |
3328 | } | |
3329 | } | |
3330 | EXPORT_SYMBOL_GPL(kmsg_dump_reason_str); | |
3331 | ||
456b565c SK |
3332 | /** |
3333 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
3334 | * @reason: the reason (oops, panic etc) for dumping | |
3335 | * | |
e2ae715d KS |
3336 | * Call each of the registered dumper's dump() callback, which can |
3337 | * retrieve the kmsg records with kmsg_dump_get_line() or | |
3338 | * kmsg_dump_get_buffer(). | |
456b565c SK |
3339 | */ |
3340 | void kmsg_dump(enum kmsg_dump_reason reason) | |
3341 | { | |
456b565c | 3342 | struct kmsg_dumper *dumper; |
456b565c | 3343 | |
e2ae715d KS |
3344 | rcu_read_lock(); |
3345 | list_for_each_entry_rcu(dumper, &dump_list, list) { | |
b1f6f161 PT |
3346 | enum kmsg_dump_reason max_reason = dumper->max_reason; |
3347 | ||
3348 | /* | |
3349 | * If client has not provided a specific max_reason, default | |
3350 | * to KMSG_DUMP_OOPS, unless always_kmsg_dump was set. | |
3351 | */ | |
3352 | if (max_reason == KMSG_DUMP_UNDEF) { | |
3353 | max_reason = always_kmsg_dump ? KMSG_DUMP_MAX : | |
3354 | KMSG_DUMP_OOPS; | |
3355 | } | |
3356 | if (reason > max_reason) | |
e2ae715d KS |
3357 | continue; |
3358 | ||
e2ae715d KS |
3359 | /* invoke dumper which will iterate over records */ |
3360 | dumper->dump(dumper, reason); | |
e2ae715d KS |
3361 | } |
3362 | rcu_read_unlock(); | |
3363 | } | |
3364 | ||
3365 | /** | |
a4f98765 | 3366 | * kmsg_dump_get_line - retrieve one kmsg log line |
f9f3f02d | 3367 | * @iter: kmsg dump iterator |
e2ae715d KS |
3368 | * @syslog: include the "<4>" prefixes |
3369 | * @line: buffer to copy the line to | |
3370 | * @size: maximum size of the buffer | |
3371 | * @len: length of line placed into buffer | |
3372 | * | |
3373 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
3374 | * record, and copy one record into the provided buffer. | |
3375 | * | |
3376 | * Consecutive calls will return the next available record moving | |
3377 | * towards the end of the buffer with the youngest messages. | |
3378 | * | |
3379 | * A return value of FALSE indicates that there are no more records to | |
3380 | * read. | |
3381 | */ | |
a4f98765 JO |
3382 | bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog, |
3383 | char *line, size_t size, size_t *len) | |
e2ae715d | 3384 | { |
f9f3f02d | 3385 | u64 min_seq = latched_seq_read_nolock(&clear_seq); |
896fbe20 JO |
3386 | struct printk_info info; |
3387 | unsigned int line_count; | |
3388 | struct printk_record r; | |
a4f98765 | 3389 | unsigned long flags; |
e2ae715d KS |
3390 | size_t l = 0; |
3391 | bool ret = false; | |
3392 | ||
f9f3f02d JO |
3393 | if (iter->cur_seq < min_seq) |
3394 | iter->cur_seq = min_seq; | |
3395 | ||
a4f98765 | 3396 | printk_safe_enter_irqsave(flags); |
f35efc78 | 3397 | prb_rec_init_rd(&r, &info, line, size); |
896fbe20 | 3398 | |
896fbe20 JO |
3399 | /* Read text or count text lines? */ |
3400 | if (line) { | |
f9f3f02d | 3401 | if (!prb_read_valid(prb, iter->cur_seq, &r)) |
896fbe20 JO |
3402 | goto out; |
3403 | l = record_print_text(&r, syslog, printk_time); | |
3404 | } else { | |
f9f3f02d | 3405 | if (!prb_read_valid_info(prb, iter->cur_seq, |
896fbe20 JO |
3406 | &info, &line_count)) { |
3407 | goto out; | |
3408 | } | |
3409 | l = get_record_print_text_size(&info, line_count, syslog, | |
3410 | printk_time); | |
456b565c | 3411 | |
896fbe20 | 3412 | } |
e2ae715d | 3413 | |
f9f3f02d | 3414 | iter->cur_seq = r.info->seq + 1; |
e2ae715d | 3415 | ret = true; |
e2ae715d | 3416 | out: |
a4f98765 | 3417 | printk_safe_exit_irqrestore(flags); |
e2ae715d KS |
3418 | if (len) |
3419 | *len = l; | |
3420 | return ret; | |
3421 | } | |
3422 | EXPORT_SYMBOL_GPL(kmsg_dump_get_line); | |
3423 | ||
3424 | /** | |
3425 | * kmsg_dump_get_buffer - copy kmsg log lines | |
f9f3f02d | 3426 | * @iter: kmsg dump iterator |
e2ae715d | 3427 | * @syslog: include the "<4>" prefixes |
4f0f4af5 | 3428 | * @buf: buffer to copy the line to |
e2ae715d | 3429 | * @size: maximum size of the buffer |
726b5097 | 3430 | * @len_out: length of line placed into buffer |
e2ae715d KS |
3431 | * |
3432 | * Start at the end of the kmsg buffer and fill the provided buffer | |
547bbf7d | 3433 | * with as many of the *youngest* kmsg records that fit into it. |
e2ae715d KS |
3434 | * If the buffer is large enough, all available kmsg records will be |
3435 | * copied with a single call. | |
3436 | * | |
3437 | * Consecutive calls will fill the buffer with the next block of | |
3438 | * available older records, not including the earlier retrieved ones. | |
3439 | * | |
3440 | * A return value of FALSE indicates that there are no more records to | |
3441 | * read. | |
3442 | */ | |
f9f3f02d | 3443 | bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog, |
726b5097 | 3444 | char *buf, size_t size, size_t *len_out) |
e2ae715d | 3445 | { |
f9f3f02d | 3446 | u64 min_seq = latched_seq_read_nolock(&clear_seq); |
896fbe20 | 3447 | struct printk_info info; |
896fbe20 | 3448 | struct printk_record r; |
e2ae715d KS |
3449 | unsigned long flags; |
3450 | u64 seq; | |
e2ae715d | 3451 | u64 next_seq; |
726b5097 | 3452 | size_t len = 0; |
e2ae715d | 3453 | bool ret = false; |
e80c1a9d | 3454 | bool time = printk_time; |
e2ae715d | 3455 | |
5f6c7648 | 3456 | if (!buf || !size) |
e2ae715d KS |
3457 | goto out; |
3458 | ||
f9f3f02d JO |
3459 | if (iter->cur_seq < min_seq) |
3460 | iter->cur_seq = min_seq; | |
3461 | ||
996e9666 | 3462 | printk_safe_enter_irqsave(flags); |
f9f3f02d JO |
3463 | if (prb_read_valid_info(prb, iter->cur_seq, &info, NULL)) { |
3464 | if (info.seq != iter->cur_seq) { | |
13791c80 | 3465 | /* messages are gone, move to first available one */ |
f9f3f02d | 3466 | iter->cur_seq = info.seq; |
13791c80 | 3467 | } |
e2ae715d KS |
3468 | } |
3469 | ||
3470 | /* last entry */ | |
f9f3f02d | 3471 | if (iter->cur_seq >= iter->next_seq) { |
996e9666 | 3472 | printk_safe_exit_irqrestore(flags); |
e2ae715d KS |
3473 | goto out; |
3474 | } | |
3475 | ||
726b5097 JO |
3476 | /* |
3477 | * Find first record that fits, including all following records, | |
4260e0e5 JO |
3478 | * into the user-provided buffer for this dump. Pass in size-1 |
3479 | * because this function (by way of record_print_text()) will | |
3480 | * not write more than size-1 bytes of text into @buf. | |
726b5097 | 3481 | */ |
f9f3f02d | 3482 | seq = find_first_fitting_seq(iter->cur_seq, iter->next_seq, |
4260e0e5 | 3483 | size - 1, syslog, time); |
e2ae715d | 3484 | |
726b5097 JO |
3485 | /* |
3486 | * Next kmsg_dump_get_buffer() invocation will dump block of | |
3487 | * older records stored right before this one. | |
3488 | */ | |
e2ae715d | 3489 | next_seq = seq; |
e2ae715d | 3490 | |
726b5097 JO |
3491 | prb_rec_init_rd(&r, &info, buf, size); |
3492 | ||
3493 | len = 0; | |
3494 | prb_for_each_record(seq, prb, seq, &r) { | |
f9f3f02d | 3495 | if (r.info->seq >= iter->next_seq) |
896fbe20 JO |
3496 | break; |
3497 | ||
726b5097 | 3498 | len += record_print_text(&r, syslog, time); |
896fbe20 | 3499 | |
726b5097 JO |
3500 | /* Adjust record to store to remaining buffer space. */ |
3501 | prb_rec_init_rd(&r, &info, buf + len, size - len); | |
e2ae715d KS |
3502 | } |
3503 | ||
f9f3f02d | 3504 | iter->next_seq = next_seq; |
e2ae715d | 3505 | ret = true; |
996e9666 | 3506 | printk_safe_exit_irqrestore(flags); |
e2ae715d | 3507 | out: |
726b5097 JO |
3508 | if (len_out) |
3509 | *len_out = len; | |
e2ae715d KS |
3510 | return ret; |
3511 | } | |
3512 | EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); | |
456b565c | 3513 | |
e2ae715d | 3514 | /** |
325606af | 3515 | * kmsg_dump_rewind - reset the iterator |
f9f3f02d | 3516 | * @iter: kmsg dump iterator |
e2ae715d KS |
3517 | * |
3518 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
3519 | * kmsg_dump_get_buffer() can be called again and used multiple | |
3520 | * times within the same dumper.dump() callback. | |
3521 | */ | |
f9f3f02d | 3522 | void kmsg_dump_rewind(struct kmsg_dump_iter *iter) |
e2ae715d KS |
3523 | { |
3524 | unsigned long flags; | |
3525 | ||
996e9666 | 3526 | printk_safe_enter_irqsave(flags); |
a4f98765 JO |
3527 | iter->cur_seq = latched_seq_read_nolock(&clear_seq); |
3528 | iter->next_seq = prb_next_seq(prb); | |
996e9666 | 3529 | printk_safe_exit_irqrestore(flags); |
456b565c | 3530 | } |
e2ae715d | 3531 | EXPORT_SYMBOL_GPL(kmsg_dump_rewind); |
196779b9 | 3532 | |
7ef3d2fd | 3533 | #endif |