Commit | Line | Data |
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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 | /* | |
4dc64682 JO |
82 | * console_mutex protects console_list updates and console->flags updates. |
83 | * The flags are synchronized only for consoles that are registered, i.e. | |
84 | * accessible via the console list. | |
85 | */ | |
86 | static DEFINE_MUTEX(console_mutex); | |
87 | ||
1da177e4 | 88 | /* |
848a9c10 JO |
89 | * console_sem protects updates to console->seq and console_suspended, |
90 | * and also provides serialization for console printing. | |
1da177e4 | 91 | */ |
5b8c4f23 | 92 | static DEFINE_SEMAPHORE(console_sem); |
d9a4af56 TG |
93 | HLIST_HEAD(console_list); |
94 | EXPORT_SYMBOL_GPL(console_list); | |
6c4afa79 | 95 | DEFINE_STATIC_SRCU(console_srcu); |
a29d1cfe | 96 | |
c39ea0b9 FT |
97 | /* |
98 | * System may need to suppress printk message under certain | |
99 | * circumstances, like after kernel panic happens. | |
100 | */ | |
101 | int __read_mostly suppress_printk; | |
102 | ||
13fb0f74 SB |
103 | /* |
104 | * During panic, heavy printk by other CPUs can delay the | |
105 | * panic and risk deadlock on console resources. | |
106 | */ | |
ce06e863 | 107 | static int __read_mostly suppress_panic_printk; |
13fb0f74 | 108 | |
daee7797 DV |
109 | #ifdef CONFIG_LOCKDEP |
110 | static struct lockdep_map console_lock_dep_map = { | |
111 | .name = "console_lock" | |
112 | }; | |
4dc64682 JO |
113 | |
114 | void lockdep_assert_console_list_lock_held(void) | |
115 | { | |
116 | lockdep_assert_held(&console_mutex); | |
117 | } | |
118 | EXPORT_SYMBOL(lockdep_assert_console_list_lock_held); | |
daee7797 DV |
119 | #endif |
120 | ||
6c4afa79 JO |
121 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
122 | bool console_srcu_read_lock_is_held(void) | |
123 | { | |
124 | return srcu_read_lock_held(&console_srcu); | |
125 | } | |
daee7797 DV |
126 | #endif |
127 | ||
750afe7b BP |
128 | enum devkmsg_log_bits { |
129 | __DEVKMSG_LOG_BIT_ON = 0, | |
130 | __DEVKMSG_LOG_BIT_OFF, | |
131 | __DEVKMSG_LOG_BIT_LOCK, | |
132 | }; | |
133 | ||
134 | enum devkmsg_log_masks { | |
135 | DEVKMSG_LOG_MASK_ON = BIT(__DEVKMSG_LOG_BIT_ON), | |
136 | DEVKMSG_LOG_MASK_OFF = BIT(__DEVKMSG_LOG_BIT_OFF), | |
137 | DEVKMSG_LOG_MASK_LOCK = BIT(__DEVKMSG_LOG_BIT_LOCK), | |
138 | }; | |
139 | ||
140 | /* Keep both the 'on' and 'off' bits clear, i.e. ratelimit by default: */ | |
141 | #define DEVKMSG_LOG_MASK_DEFAULT 0 | |
142 | ||
143 | static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; | |
144 | ||
145 | static int __control_devkmsg(char *str) | |
146 | { | |
35c35493 CY |
147 | size_t len; |
148 | ||
750afe7b BP |
149 | if (!str) |
150 | return -EINVAL; | |
151 | ||
35c35493 CY |
152 | len = str_has_prefix(str, "on"); |
153 | if (len) { | |
750afe7b | 154 | devkmsg_log = DEVKMSG_LOG_MASK_ON; |
35c35493 CY |
155 | return len; |
156 | } | |
157 | ||
158 | len = str_has_prefix(str, "off"); | |
159 | if (len) { | |
750afe7b | 160 | devkmsg_log = DEVKMSG_LOG_MASK_OFF; |
35c35493 CY |
161 | return len; |
162 | } | |
163 | ||
164 | len = str_has_prefix(str, "ratelimit"); | |
165 | if (len) { | |
750afe7b | 166 | devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; |
35c35493 | 167 | return len; |
750afe7b | 168 | } |
35c35493 | 169 | |
750afe7b BP |
170 | return -EINVAL; |
171 | } | |
172 | ||
173 | static int __init control_devkmsg(char *str) | |
174 | { | |
b665eae7 RD |
175 | if (__control_devkmsg(str) < 0) { |
176 | pr_warn("printk.devkmsg: bad option string '%s'\n", str); | |
750afe7b | 177 | return 1; |
b665eae7 | 178 | } |
750afe7b BP |
179 | |
180 | /* | |
181 | * Set sysctl string accordingly: | |
182 | */ | |
6fd78a1a SS |
183 | if (devkmsg_log == DEVKMSG_LOG_MASK_ON) |
184 | strcpy(devkmsg_log_str, "on"); | |
185 | else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF) | |
186 | strcpy(devkmsg_log_str, "off"); | |
750afe7b BP |
187 | /* else "ratelimit" which is set by default. */ |
188 | ||
189 | /* | |
190 | * Sysctl cannot change it anymore. The kernel command line setting of | |
191 | * this parameter is to force the setting to be permanent throughout the | |
192 | * runtime of the system. This is a precation measure against userspace | |
193 | * trying to be a smarta** and attempting to change it up on us. | |
194 | */ | |
195 | devkmsg_log |= DEVKMSG_LOG_MASK_LOCK; | |
196 | ||
b665eae7 | 197 | return 1; |
750afe7b BP |
198 | } |
199 | __setup("printk.devkmsg=", control_devkmsg); | |
200 | ||
201 | char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit"; | |
fdcd4073 | 202 | #if defined(CONFIG_PRINTK) && defined(CONFIG_SYSCTL) |
750afe7b | 203 | int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, |
32927393 | 204 | void *buffer, size_t *lenp, loff_t *ppos) |
750afe7b BP |
205 | { |
206 | char old_str[DEVKMSG_STR_MAX_SIZE]; | |
207 | unsigned int old; | |
208 | int err; | |
209 | ||
210 | if (write) { | |
211 | if (devkmsg_log & DEVKMSG_LOG_MASK_LOCK) | |
212 | return -EINVAL; | |
213 | ||
214 | old = devkmsg_log; | |
215 | strncpy(old_str, devkmsg_log_str, DEVKMSG_STR_MAX_SIZE); | |
216 | } | |
217 | ||
218 | err = proc_dostring(table, write, buffer, lenp, ppos); | |
219 | if (err) | |
220 | return err; | |
221 | ||
222 | if (write) { | |
223 | err = __control_devkmsg(devkmsg_log_str); | |
224 | ||
225 | /* | |
226 | * Do not accept an unknown string OR a known string with | |
227 | * trailing crap... | |
228 | */ | |
229 | if (err < 0 || (err + 1 != *lenp)) { | |
230 | ||
231 | /* ... and restore old setting. */ | |
232 | devkmsg_log = old; | |
233 | strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE); | |
234 | ||
235 | return -EINVAL; | |
236 | } | |
237 | } | |
238 | ||
239 | return 0; | |
240 | } | |
fdcd4073 | 241 | #endif /* CONFIG_PRINTK && CONFIG_SYSCTL */ |
750afe7b | 242 | |
4dc64682 JO |
243 | /** |
244 | * console_list_lock - Lock the console list | |
245 | * | |
246 | * For console list or console->flags updates | |
247 | */ | |
248 | void console_list_lock(void) | |
249 | { | |
250 | /* | |
6f883675 JO |
251 | * In unregister_console() and console_force_preferred_locked(), |
252 | * synchronize_srcu() is called with the console_list_lock held. | |
253 | * Therefore it is not allowed that the console_list_lock is taken | |
254 | * with the srcu_lock held. | |
4dc64682 JO |
255 | * |
256 | * Detecting if this context is really in the read-side critical | |
257 | * section is only possible if the appropriate debug options are | |
258 | * enabled. | |
259 | */ | |
260 | WARN_ON_ONCE(debug_lockdep_rcu_enabled() && | |
261 | srcu_read_lock_held(&console_srcu)); | |
262 | ||
263 | mutex_lock(&console_mutex); | |
264 | } | |
265 | EXPORT_SYMBOL(console_list_lock); | |
266 | ||
267 | /** | |
268 | * console_list_unlock - Unlock the console list | |
269 | * | |
270 | * Counterpart to console_list_lock() | |
271 | */ | |
272 | void console_list_unlock(void) | |
273 | { | |
274 | mutex_unlock(&console_mutex); | |
275 | } | |
276 | EXPORT_SYMBOL(console_list_unlock); | |
277 | ||
6c4afa79 JO |
278 | /** |
279 | * console_srcu_read_lock - Register a new reader for the | |
280 | * SRCU-protected console list | |
281 | * | |
282 | * Use for_each_console_srcu() to iterate the console list | |
283 | * | |
284 | * Context: Any context. | |
5074ffbe | 285 | * Return: A cookie to pass to console_srcu_read_unlock(). |
6c4afa79 JO |
286 | */ |
287 | int console_srcu_read_lock(void) | |
288 | { | |
289 | return srcu_read_lock_nmisafe(&console_srcu); | |
290 | } | |
291 | EXPORT_SYMBOL(console_srcu_read_lock); | |
292 | ||
293 | /** | |
294 | * console_srcu_read_unlock - Unregister an old reader from | |
295 | * the SRCU-protected console list | |
5074ffbe | 296 | * @cookie: cookie returned from console_srcu_read_lock() |
6c4afa79 JO |
297 | * |
298 | * Counterpart to console_srcu_read_lock() | |
299 | */ | |
300 | void console_srcu_read_unlock(int cookie) | |
301 | { | |
302 | srcu_read_unlock_nmisafe(&console_srcu, cookie); | |
303 | } | |
304 | EXPORT_SYMBOL(console_srcu_read_unlock); | |
305 | ||
bd8d7cf5 JK |
306 | /* |
307 | * Helper macros to handle lockdep when locking/unlocking console_sem. We use | |
308 | * macros instead of functions so that _RET_IP_ contains useful information. | |
309 | */ | |
310 | #define down_console_sem() do { \ | |
311 | down(&console_sem);\ | |
312 | mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ | |
313 | } while (0) | |
314 | ||
315 | static int __down_trylock_console_sem(unsigned long ip) | |
316 | { | |
f975237b SS |
317 | int lock_failed; |
318 | unsigned long flags; | |
319 | ||
320 | /* | |
321 | * Here and in __up_console_sem() we need to be in safe mode, | |
322 | * because spindump/WARN/etc from under console ->lock will | |
323 | * deadlock in printk()->down_trylock_console_sem() otherwise. | |
324 | */ | |
325 | printk_safe_enter_irqsave(flags); | |
326 | lock_failed = down_trylock(&console_sem); | |
327 | printk_safe_exit_irqrestore(flags); | |
328 | ||
329 | if (lock_failed) | |
bd8d7cf5 JK |
330 | return 1; |
331 | mutex_acquire(&console_lock_dep_map, 0, 1, ip); | |
332 | return 0; | |
333 | } | |
334 | #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) | |
335 | ||
f975237b SS |
336 | static void __up_console_sem(unsigned long ip) |
337 | { | |
338 | unsigned long flags; | |
339 | ||
5facae4f | 340 | mutex_release(&console_lock_dep_map, ip); |
f975237b SS |
341 | |
342 | printk_safe_enter_irqsave(flags); | |
343 | up(&console_sem); | |
344 | printk_safe_exit_irqrestore(flags); | |
345 | } | |
346 | #define up_console_sem() __up_console_sem(_RET_IP_) | |
bd8d7cf5 | 347 | |
77498617 SB |
348 | static bool panic_in_progress(void) |
349 | { | |
350 | return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID); | |
351 | } | |
352 | ||
007eeab7 PM |
353 | /* |
354 | * This is used for debugging the mess that is the VT code by | |
355 | * keeping track if we have the console semaphore held. It's | |
356 | * definitely not the perfect debug tool (we don't know if _WE_ | |
357 | * hold it and are racing, but it helps tracking those weird code | |
358 | * paths in the console code where we end up in places I want | |
359 | * locked without the console semaphore held). | |
360 | */ | |
361 | static int console_locked, console_suspended; | |
1da177e4 | 362 | |
1da177e4 LT |
363 | /* |
364 | * Array of consoles built from command line options (console=) | |
365 | */ | |
1da177e4 LT |
366 | |
367 | #define MAX_CMDLINECONSOLES 8 | |
368 | ||
369 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
d197c43d | 370 | |
1da177e4 | 371 | static int preferred_console = -1; |
9e124fe1 MA |
372 | int console_set_on_cmdline; |
373 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
374 | |
375 | /* Flag: console code may call schedule() */ | |
376 | static int console_may_schedule; | |
377 | ||
cca10d58 SS |
378 | enum con_msg_format_flags { |
379 | MSG_FORMAT_DEFAULT = 0, | |
380 | MSG_FORMAT_SYSLOG = (1 << 0), | |
381 | }; | |
382 | ||
383 | static int console_msg_format = MSG_FORMAT_DEFAULT; | |
384 | ||
7ff9554b | 385 | /* |
896fbe20 | 386 | * The printk log buffer consists of a sequenced collection of records, each |
74caba7f JO |
387 | * containing variable length message text. Every record also contains its |
388 | * own meta-data (@info). | |
7ff9554b | 389 | * |
896fbe20 JO |
390 | * Every record meta-data carries the timestamp in microseconds, as well as |
391 | * the standard userspace syslog level and syslog facility. The usual kernel | |
392 | * messages use LOG_KERN; userspace-injected messages always carry a matching | |
393 | * syslog facility, by default LOG_USER. The origin of every message can be | |
394 | * reliably determined that way. | |
7ff9554b | 395 | * |
896fbe20 JO |
396 | * The human readable log message of a record is available in @text, the |
397 | * length of the message text in @text_len. The stored message is not | |
398 | * terminated. | |
7ff9554b | 399 | * |
896fbe20 | 400 | * Optionally, a record can carry a dictionary of properties (key/value |
74caba7f | 401 | * pairs), to provide userspace with a machine-readable message context. |
e11fea92 KS |
402 | * |
403 | * Examples for well-defined, commonly used property names are: | |
404 | * DEVICE=b12:8 device identifier | |
405 | * b12:8 block dev_t | |
406 | * c127:3 char dev_t | |
407 | * n8 netdev ifindex | |
408 | * +sound:card0 subsystem:devname | |
409 | * SUBSYSTEM=pci driver-core subsystem name | |
410 | * | |
74caba7f JO |
411 | * Valid characters in property names are [a-zA-Z0-9.-_]. Property names |
412 | * and values are terminated by a '\0' character. | |
e11fea92 | 413 | * |
896fbe20 | 414 | * Example of record values: |
74caba7f JO |
415 | * record.text_buf = "it's a line" (unterminated) |
416 | * record.info.seq = 56 | |
417 | * record.info.ts_nsec = 36863 | |
418 | * record.info.text_len = 11 | |
419 | * record.info.facility = 0 (LOG_KERN) | |
420 | * record.info.flags = 0 | |
421 | * record.info.level = 3 (LOG_ERR) | |
422 | * record.info.caller_id = 299 (task 299) | |
423 | * record.info.dev_info.subsystem = "pci" (terminated) | |
424 | * record.info.dev_info.device = "+pci:0000:00:01.0" (terminated) | |
896fbe20 JO |
425 | * |
426 | * The 'struct printk_info' buffer must never be directly exported to | |
e11fea92 KS |
427 | * userspace, it is a kernel-private implementation detail that might |
428 | * need to be changed in the future, when the requirements change. | |
429 | * | |
430 | * /dev/kmsg exports the structured data in the following line format: | |
b389645f AO |
431 | * "<level>,<sequnum>,<timestamp>,<contflag>[,additional_values, ... ];<message text>\n" |
432 | * | |
433 | * Users of the export format should ignore possible additional values | |
434 | * separated by ',', and find the message after the ';' character. | |
e11fea92 KS |
435 | * |
436 | * The optional key/value pairs are attached as continuation lines starting | |
437 | * with a space character and terminated by a newline. All possible | |
438 | * non-prinatable characters are escaped in the "\xff" notation. | |
7ff9554b KS |
439 | */ |
440 | ||
636babdc | 441 | /* syslog_lock protects syslog_* variables and write access to clear_seq. */ |
b371cbb5 | 442 | static DEFINE_MUTEX(syslog_lock); |
636babdc | 443 | |
96efedf1 | 444 | #ifdef CONFIG_PRINTK |
dc72c32e | 445 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
636babdc | 446 | /* All 3 protected by @syslog_lock. */ |
7f3a781d KS |
447 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
448 | static u64 syslog_seq; | |
eb02dac9 | 449 | static size_t syslog_partial; |
e80c1a9d | 450 | static bool syslog_time; |
7ff9554b | 451 | |
7d7a23a9 JO |
452 | struct latched_seq { |
453 | seqcount_latch_t latch; | |
454 | u64 val[2]; | |
455 | }; | |
456 | ||
457 | /* | |
458 | * The next printk record to read after the last 'clear' command. There are | |
459 | * two copies (updated with seqcount_latch) so that reads can locklessly | |
636babdc | 460 | * access a valid value. Writers are synchronized by @syslog_lock. |
7d7a23a9 JO |
461 | */ |
462 | static struct latched_seq clear_seq = { | |
463 | .latch = SEQCNT_LATCH_ZERO(clear_seq.latch), | |
464 | .val[0] = 0, | |
465 | .val[1] = 0, | |
466 | }; | |
7ff9554b | 467 | |
15ff2069 TH |
468 | #ifdef CONFIG_PRINTK_CALLER |
469 | #define PREFIX_MAX 48 | |
470 | #else | |
70498253 | 471 | #define PREFIX_MAX 32 |
15ff2069 | 472 | #endif |
cf5b0208 JO |
473 | |
474 | /* the maximum size of a formatted record (i.e. with prefix added per line) */ | |
475 | #define CONSOLE_LOG_MAX 1024 | |
476 | ||
03a749e6 JO |
477 | /* the maximum size for a dropped text message */ |
478 | #define DROPPED_TEXT_MAX 64 | |
479 | ||
cf5b0208 JO |
480 | /* the maximum size allowed to be reserved for a record */ |
481 | #define LOG_LINE_MAX (CONSOLE_LOG_MAX - PREFIX_MAX) | |
7f3a781d | 482 | |
3824657c MK |
483 | #define LOG_LEVEL(v) ((v) & 0x07) |
484 | #define LOG_FACILITY(v) ((v) >> 3 & 0xff) | |
485 | ||
7f3a781d | 486 | /* record buffer */ |
896fbe20 | 487 | #define LOG_ALIGN __alignof__(unsigned long) |
7f3a781d | 488 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
e6fe3e5b | 489 | #define LOG_BUF_LEN_MAX (u32)(1 << 31) |
f8450fca | 490 | static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); |
7f3a781d KS |
491 | static char *log_buf = __log_buf; |
492 | static u32 log_buf_len = __LOG_BUF_LEN; | |
493 | ||
896fbe20 JO |
494 | /* |
495 | * Define the average message size. This only affects the number of | |
496 | * descriptors that will be available. Underestimating is better than | |
497 | * overestimating (too many available descriptors is better than not enough). | |
896fbe20 JO |
498 | */ |
499 | #define PRB_AVGBITS 5 /* 32 character average length */ | |
500 | ||
501 | #if CONFIG_LOG_BUF_SHIFT <= PRB_AVGBITS | |
502 | #error CONFIG_LOG_BUF_SHIFT value too small. | |
503 | #endif | |
504 | _DEFINE_PRINTKRB(printk_rb_static, CONFIG_LOG_BUF_SHIFT - PRB_AVGBITS, | |
f35efc78 | 505 | PRB_AVGBITS, &__log_buf[0]); |
896fbe20 JO |
506 | |
507 | static struct printk_ringbuffer printk_rb_dynamic; | |
508 | ||
509 | static struct printk_ringbuffer *prb = &printk_rb_static; | |
510 | ||
ab6f762f SS |
511 | /* |
512 | * We cannot access per-CPU data (e.g. per-CPU flush irq_work) before | |
513 | * per_cpu_areas are initialised. This variable is set to true when | |
514 | * it's safe to access per-CPU data. | |
515 | */ | |
78ba392c | 516 | static bool __printk_percpu_data_ready __ro_after_init; |
ab6f762f SS |
517 | |
518 | bool printk_percpu_data_ready(void) | |
519 | { | |
520 | return __printk_percpu_data_ready; | |
521 | } | |
522 | ||
636babdc | 523 | /* Must be called under syslog_lock. */ |
7d7a23a9 JO |
524 | static void latched_seq_write(struct latched_seq *ls, u64 val) |
525 | { | |
526 | raw_write_seqcount_latch(&ls->latch); | |
527 | ls->val[0] = val; | |
528 | raw_write_seqcount_latch(&ls->latch); | |
529 | ls->val[1] = val; | |
530 | } | |
531 | ||
532 | /* Can be called from any context. */ | |
533 | static u64 latched_seq_read_nolock(struct latched_seq *ls) | |
534 | { | |
535 | unsigned int seq; | |
536 | unsigned int idx; | |
537 | u64 val; | |
538 | ||
539 | do { | |
540 | seq = raw_read_seqcount_latch(&ls->latch); | |
541 | idx = seq & 0x1; | |
542 | val = ls->val[idx]; | |
543 | } while (read_seqcount_latch_retry(&ls->latch, seq)); | |
544 | ||
545 | return val; | |
546 | } | |
547 | ||
14c4000a VH |
548 | /* Return log buffer address */ |
549 | char *log_buf_addr_get(void) | |
550 | { | |
551 | return log_buf; | |
552 | } | |
553 | ||
554 | /* Return log buffer size */ | |
555 | u32 log_buf_len_get(void) | |
556 | { | |
557 | return log_buf_len; | |
558 | } | |
559 | ||
55bd53a4 PM |
560 | /* |
561 | * Define how much of the log buffer we could take at maximum. The value | |
562 | * must be greater than two. Note that only half of the buffer is available | |
563 | * when the index points to the middle. | |
564 | */ | |
565 | #define MAX_LOG_TAKE_PART 4 | |
566 | static const char trunc_msg[] = "<truncated>"; | |
567 | ||
896fbe20 | 568 | static void truncate_msg(u16 *text_len, u16 *trunc_msg_len) |
55bd53a4 PM |
569 | { |
570 | /* | |
571 | * The message should not take the whole buffer. Otherwise, it might | |
572 | * get removed too soon. | |
573 | */ | |
574 | u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART; | |
896fbe20 | 575 | |
55bd53a4 PM |
576 | if (*text_len > max_text_len) |
577 | *text_len = max_text_len; | |
896fbe20 JO |
578 | |
579 | /* enable the warning message (if there is room) */ | |
55bd53a4 | 580 | *trunc_msg_len = strlen(trunc_msg); |
896fbe20 JO |
581 | if (*text_len >= *trunc_msg_len) |
582 | *text_len -= *trunc_msg_len; | |
583 | else | |
584 | *trunc_msg_len = 0; | |
55bd53a4 PM |
585 | } |
586 | ||
e99aa461 | 587 | int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); |
637241a9 KC |
588 | |
589 | static int syslog_action_restricted(int type) | |
590 | { | |
591 | if (dmesg_restrict) | |
592 | return 1; | |
593 | /* | |
594 | * Unless restricted, we allow "read all" and "get buffer size" | |
595 | * for everybody. | |
596 | */ | |
597 | return type != SYSLOG_ACTION_READ_ALL && | |
598 | type != SYSLOG_ACTION_SIZE_BUFFER; | |
599 | } | |
600 | ||
c71b02e4 | 601 | static int check_syslog_permissions(int type, int source) |
637241a9 KC |
602 | { |
603 | /* | |
604 | * If this is from /proc/kmsg and we've already opened it, then we've | |
605 | * already done the capabilities checks at open time. | |
606 | */ | |
3ea4331c | 607 | if (source == SYSLOG_FROM_PROC && type != SYSLOG_ACTION_OPEN) |
d194e5d6 | 608 | goto ok; |
637241a9 KC |
609 | |
610 | if (syslog_action_restricted(type)) { | |
611 | if (capable(CAP_SYSLOG)) | |
d194e5d6 | 612 | goto ok; |
637241a9 KC |
613 | /* |
614 | * For historical reasons, accept CAP_SYS_ADMIN too, with | |
615 | * a warning. | |
616 | */ | |
617 | if (capable(CAP_SYS_ADMIN)) { | |
618 | pr_warn_once("%s (%d): Attempt to access syslog with " | |
619 | "CAP_SYS_ADMIN but no CAP_SYSLOG " | |
620 | "(deprecated).\n", | |
621 | current->comm, task_pid_nr(current)); | |
d194e5d6 | 622 | goto ok; |
637241a9 KC |
623 | } |
624 | return -EPERM; | |
625 | } | |
d194e5d6 | 626 | ok: |
637241a9 KC |
627 | return security_syslog(type); |
628 | } | |
629 | ||
d43ff430 TH |
630 | static void append_char(char **pp, char *e, char c) |
631 | { | |
632 | if (*pp < e) | |
633 | *(*pp)++ = c; | |
634 | } | |
637241a9 | 635 | |
896fbe20 JO |
636 | static ssize_t info_print_ext_header(char *buf, size_t size, |
637 | struct printk_info *info) | |
0a295e67 | 638 | { |
896fbe20 | 639 | u64 ts_usec = info->ts_nsec; |
15ff2069 TH |
640 | char caller[20]; |
641 | #ifdef CONFIG_PRINTK_CALLER | |
896fbe20 | 642 | u32 id = info->caller_id; |
15ff2069 TH |
643 | |
644 | snprintf(caller, sizeof(caller), ",caller=%c%u", | |
645 | id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); | |
646 | #else | |
647 | caller[0] = '\0'; | |
648 | #endif | |
0a295e67 TH |
649 | |
650 | do_div(ts_usec, 1000); | |
651 | ||
15ff2069 | 652 | return scnprintf(buf, size, "%u,%llu,%llu,%c%s;", |
896fbe20 JO |
653 | (info->facility << 3) | info->level, info->seq, |
654 | ts_usec, info->flags & LOG_CONT ? 'c' : '-', caller); | |
0a295e67 TH |
655 | } |
656 | ||
74caba7f JO |
657 | static ssize_t msg_add_ext_text(char *buf, size_t size, |
658 | const char *text, size_t text_len, | |
659 | unsigned char endc) | |
0a295e67 TH |
660 | { |
661 | char *p = buf, *e = buf + size; | |
662 | size_t i; | |
663 | ||
664 | /* escape non-printable characters */ | |
665 | for (i = 0; i < text_len; i++) { | |
666 | unsigned char c = text[i]; | |
667 | ||
668 | if (c < ' ' || c >= 127 || c == '\\') | |
669 | p += scnprintf(p, e - p, "\\x%02x", c); | |
670 | else | |
671 | append_char(&p, e, c); | |
672 | } | |
74caba7f | 673 | append_char(&p, e, endc); |
0a295e67 | 674 | |
74caba7f JO |
675 | return p - buf; |
676 | } | |
0a295e67 | 677 | |
74caba7f JO |
678 | static ssize_t msg_add_dict_text(char *buf, size_t size, |
679 | const char *key, const char *val) | |
680 | { | |
681 | size_t val_len = strlen(val); | |
682 | ssize_t len; | |
0a295e67 | 683 | |
74caba7f JO |
684 | if (!val_len) |
685 | return 0; | |
0a295e67 | 686 | |
74caba7f JO |
687 | len = msg_add_ext_text(buf, size, "", 0, ' '); /* dict prefix */ |
688 | len += msg_add_ext_text(buf + len, size - len, key, strlen(key), '='); | |
689 | len += msg_add_ext_text(buf + len, size - len, val, val_len, '\n'); | |
0a295e67 | 690 | |
74caba7f JO |
691 | return len; |
692 | } | |
0a295e67 | 693 | |
74caba7f JO |
694 | static ssize_t msg_print_ext_body(char *buf, size_t size, |
695 | char *text, size_t text_len, | |
696 | struct dev_printk_info *dev_info) | |
697 | { | |
698 | ssize_t len; | |
0a295e67 | 699 | |
74caba7f JO |
700 | len = msg_add_ext_text(buf, size, text, text_len, '\n'); |
701 | ||
702 | if (!dev_info) | |
703 | goto out; | |
704 | ||
705 | len += msg_add_dict_text(buf + len, size - len, "SUBSYSTEM", | |
706 | dev_info->subsystem); | |
707 | len += msg_add_dict_text(buf + len, size - len, "DEVICE", | |
708 | dev_info->device); | |
709 | out: | |
710 | return len; | |
0a295e67 TH |
711 | } |
712 | ||
e11fea92 KS |
713 | /* /dev/kmsg - userspace message inject/listen interface */ |
714 | struct devkmsg_user { | |
35b2b163 | 715 | atomic64_t seq; |
750afe7b | 716 | struct ratelimit_state rs; |
e11fea92 | 717 | struct mutex lock; |
d43ff430 | 718 | char buf[CONSOLE_EXT_LOG_MAX]; |
896fbe20 JO |
719 | |
720 | struct printk_info info; | |
721 | char text_buf[CONSOLE_EXT_LOG_MAX]; | |
896fbe20 | 722 | struct printk_record record; |
e11fea92 KS |
723 | }; |
724 | ||
9adcfaff TH |
725 | static __printf(3, 4) __cold |
726 | int devkmsg_emit(int facility, int level, const char *fmt, ...) | |
727 | { | |
728 | va_list args; | |
729 | int r; | |
730 | ||
731 | va_start(args, fmt); | |
74caba7f | 732 | r = vprintk_emit(facility, level, NULL, fmt, args); |
9adcfaff TH |
733 | va_end(args); |
734 | ||
735 | return r; | |
736 | } | |
737 | ||
849f3127 | 738 | static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from) |
e11fea92 KS |
739 | { |
740 | char *buf, *line; | |
e11fea92 KS |
741 | int level = default_message_loglevel; |
742 | int facility = 1; /* LOG_USER */ | |
750afe7b BP |
743 | struct file *file = iocb->ki_filp; |
744 | struct devkmsg_user *user = file->private_data; | |
66ee59af | 745 | size_t len = iov_iter_count(from); |
e11fea92 KS |
746 | ssize_t ret = len; |
747 | ||
750afe7b | 748 | if (!user || len > LOG_LINE_MAX) |
e11fea92 | 749 | return -EINVAL; |
750afe7b BP |
750 | |
751 | /* Ignore when user logging is disabled. */ | |
752 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) | |
753 | return len; | |
754 | ||
755 | /* Ratelimit when not explicitly enabled. */ | |
756 | if (!(devkmsg_log & DEVKMSG_LOG_MASK_ON)) { | |
757 | if (!___ratelimit(&user->rs, current->comm)) | |
758 | return ret; | |
759 | } | |
760 | ||
e11fea92 KS |
761 | buf = kmalloc(len+1, GFP_KERNEL); |
762 | if (buf == NULL) | |
763 | return -ENOMEM; | |
764 | ||
849f3127 | 765 | buf[len] = '\0'; |
cbbd26b8 | 766 | if (!copy_from_iter_full(buf, len, from)) { |
849f3127 AV |
767 | kfree(buf); |
768 | return -EFAULT; | |
e11fea92 KS |
769 | } |
770 | ||
771 | /* | |
772 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace | |
773 | * the decimal value represents 32bit, the lower 3 bit are the log | |
774 | * level, the rest are the log facility. | |
775 | * | |
776 | * If no prefix or no userspace facility is specified, we | |
777 | * enforce LOG_USER, to be able to reliably distinguish | |
778 | * kernel-generated messages from userspace-injected ones. | |
779 | */ | |
780 | line = buf; | |
781 | if (line[0] == '<') { | |
782 | char *endp = NULL; | |
3824657c | 783 | unsigned int u; |
e11fea92 | 784 | |
3824657c | 785 | u = simple_strtoul(line + 1, &endp, 10); |
e11fea92 | 786 | if (endp && endp[0] == '>') { |
3824657c MK |
787 | level = LOG_LEVEL(u); |
788 | if (LOG_FACILITY(u) != 0) | |
789 | facility = LOG_FACILITY(u); | |
e11fea92 | 790 | endp++; |
e11fea92 KS |
791 | line = endp; |
792 | } | |
793 | } | |
e11fea92 | 794 | |
9adcfaff | 795 | devkmsg_emit(facility, level, "%s", line); |
e11fea92 KS |
796 | kfree(buf); |
797 | return ret; | |
798 | } | |
799 | ||
800 | static ssize_t devkmsg_read(struct file *file, char __user *buf, | |
801 | size_t count, loff_t *ppos) | |
802 | { | |
803 | struct devkmsg_user *user = file->private_data; | |
896fbe20 | 804 | struct printk_record *r = &user->record; |
e11fea92 KS |
805 | size_t len; |
806 | ssize_t ret; | |
807 | ||
808 | if (!user) | |
809 | return -EBADF; | |
810 | ||
4a77a5a0 YL |
811 | ret = mutex_lock_interruptible(&user->lock); |
812 | if (ret) | |
813 | return ret; | |
de6fcbdb | 814 | |
35b2b163 | 815 | if (!prb_read_valid(prb, atomic64_read(&user->seq), r)) { |
e11fea92 KS |
816 | if (file->f_flags & O_NONBLOCK) { |
817 | ret = -EAGAIN; | |
e11fea92 KS |
818 | goto out; |
819 | } | |
820 | ||
1f5d7830 JO |
821 | /* |
822 | * Guarantee this task is visible on the waitqueue before | |
823 | * checking the wake condition. | |
824 | * | |
825 | * The full memory barrier within set_current_state() of | |
826 | * prepare_to_wait_event() pairs with the full memory barrier | |
827 | * within wq_has_sleeper(). | |
828 | * | |
5341b93d | 829 | * This pairs with __wake_up_klogd:A. |
1f5d7830 | 830 | */ |
e11fea92 | 831 | ret = wait_event_interruptible(log_wait, |
1f5d7830 JO |
832 | prb_read_valid(prb, |
833 | atomic64_read(&user->seq), r)); /* LMM(devkmsg_read:A) */ | |
e11fea92 KS |
834 | if (ret) |
835 | goto out; | |
e11fea92 KS |
836 | } |
837 | ||
35b2b163 | 838 | if (r->info->seq != atomic64_read(&user->seq)) { |
e11fea92 | 839 | /* our last seen message is gone, return error and reset */ |
35b2b163 | 840 | atomic64_set(&user->seq, r->info->seq); |
e11fea92 | 841 | ret = -EPIPE; |
e11fea92 KS |
842 | goto out; |
843 | } | |
844 | ||
896fbe20 | 845 | len = info_print_ext_header(user->buf, sizeof(user->buf), r->info); |
0a295e67 | 846 | len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len, |
74caba7f JO |
847 | &r->text_buf[0], r->info->text_len, |
848 | &r->info->dev_info); | |
d39f3d77 | 849 | |
35b2b163 | 850 | atomic64_set(&user->seq, r->info->seq + 1); |
e11fea92 KS |
851 | |
852 | if (len > count) { | |
853 | ret = -EINVAL; | |
854 | goto out; | |
855 | } | |
856 | ||
857 | if (copy_to_user(buf, user->buf, len)) { | |
858 | ret = -EFAULT; | |
859 | goto out; | |
860 | } | |
861 | ret = len; | |
862 | out: | |
863 | mutex_unlock(&user->lock); | |
864 | return ret; | |
865 | } | |
866 | ||
bc885f1a BM |
867 | /* |
868 | * Be careful when modifying this function!!! | |
869 | * | |
870 | * Only few operations are supported because the device works only with the | |
871 | * entire variable length messages (records). Non-standard values are | |
872 | * returned in the other cases and has been this way for quite some time. | |
873 | * User space applications might depend on this behavior. | |
874 | */ | |
e11fea92 KS |
875 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) |
876 | { | |
877 | struct devkmsg_user *user = file->private_data; | |
878 | loff_t ret = 0; | |
879 | ||
880 | if (!user) | |
881 | return -EBADF; | |
882 | if (offset) | |
883 | return -ESPIPE; | |
884 | ||
e11fea92 KS |
885 | switch (whence) { |
886 | case SEEK_SET: | |
887 | /* the first record */ | |
35b2b163 | 888 | atomic64_set(&user->seq, prb_first_valid_seq(prb)); |
e11fea92 KS |
889 | break; |
890 | case SEEK_DATA: | |
891 | /* | |
892 | * The first record after the last SYSLOG_ACTION_CLEAR, | |
893 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself | |
894 | * changes no global state, and does not clear anything. | |
895 | */ | |
35b2b163 | 896 | atomic64_set(&user->seq, latched_seq_read_nolock(&clear_seq)); |
e11fea92 KS |
897 | break; |
898 | case SEEK_END: | |
899 | /* after the last record */ | |
35b2b163 | 900 | atomic64_set(&user->seq, prb_next_seq(prb)); |
e11fea92 KS |
901 | break; |
902 | default: | |
903 | ret = -EINVAL; | |
904 | } | |
e11fea92 KS |
905 | return ret; |
906 | } | |
907 | ||
9dd95748 | 908 | static __poll_t devkmsg_poll(struct file *file, poll_table *wait) |
e11fea92 KS |
909 | { |
910 | struct devkmsg_user *user = file->private_data; | |
13791c80 | 911 | struct printk_info info; |
9dd95748 | 912 | __poll_t ret = 0; |
e11fea92 KS |
913 | |
914 | if (!user) | |
a9a08845 | 915 | return EPOLLERR|EPOLLNVAL; |
e11fea92 KS |
916 | |
917 | poll_wait(file, &log_wait, wait); | |
918 | ||
35b2b163 | 919 | if (prb_read_valid_info(prb, atomic64_read(&user->seq), &info, NULL)) { |
e11fea92 | 920 | /* return error when data has vanished underneath us */ |
35b2b163 | 921 | if (info.seq != atomic64_read(&user->seq)) |
a9a08845 | 922 | ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI; |
0a285317 | 923 | else |
a9a08845 | 924 | ret = EPOLLIN|EPOLLRDNORM; |
e11fea92 | 925 | } |
e11fea92 KS |
926 | |
927 | return ret; | |
928 | } | |
929 | ||
930 | static int devkmsg_open(struct inode *inode, struct file *file) | |
931 | { | |
932 | struct devkmsg_user *user; | |
933 | int err; | |
934 | ||
750afe7b BP |
935 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) |
936 | return -EPERM; | |
e11fea92 | 937 | |
750afe7b BP |
938 | /* write-only does not need any file context */ |
939 | if ((file->f_flags & O_ACCMODE) != O_WRONLY) { | |
940 | err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, | |
941 | SYSLOG_FROM_READER); | |
942 | if (err) | |
943 | return err; | |
944 | } | |
e11fea92 | 945 | |
9980c425 | 946 | user = kvmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); |
e11fea92 KS |
947 | if (!user) |
948 | return -ENOMEM; | |
949 | ||
750afe7b BP |
950 | ratelimit_default_init(&user->rs); |
951 | ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE); | |
952 | ||
e11fea92 KS |
953 | mutex_init(&user->lock); |
954 | ||
896fbe20 | 955 | prb_rec_init_rd(&user->record, &user->info, |
f35efc78 | 956 | &user->text_buf[0], sizeof(user->text_buf)); |
896fbe20 | 957 | |
35b2b163 | 958 | atomic64_set(&user->seq, prb_first_valid_seq(prb)); |
e11fea92 KS |
959 | |
960 | file->private_data = user; | |
961 | return 0; | |
962 | } | |
963 | ||
964 | static int devkmsg_release(struct inode *inode, struct file *file) | |
965 | { | |
966 | struct devkmsg_user *user = file->private_data; | |
967 | ||
968 | if (!user) | |
969 | return 0; | |
970 | ||
750afe7b BP |
971 | ratelimit_state_exit(&user->rs); |
972 | ||
e11fea92 | 973 | mutex_destroy(&user->lock); |
9980c425 | 974 | kvfree(user); |
e11fea92 KS |
975 | return 0; |
976 | } | |
977 | ||
978 | const struct file_operations kmsg_fops = { | |
979 | .open = devkmsg_open, | |
980 | .read = devkmsg_read, | |
849f3127 | 981 | .write_iter = devkmsg_write, |
e11fea92 KS |
982 | .llseek = devkmsg_llseek, |
983 | .poll = devkmsg_poll, | |
984 | .release = devkmsg_release, | |
985 | }; | |
986 | ||
692f66f2 | 987 | #ifdef CONFIG_CRASH_CORE |
04d491ab | 988 | /* |
4c1ace64 | 989 | * This appends the listed symbols to /proc/vmcore |
04d491ab | 990 | * |
4c1ace64 | 991 | * /proc/vmcore is used by various utilities, like crash and makedumpfile to |
04d491ab NH |
992 | * obtain access to symbols that are otherwise very difficult to locate. These |
993 | * symbols are specifically used so that utilities can access and extract the | |
994 | * dmesg log from a vmcore file after a crash. | |
995 | */ | |
692f66f2 | 996 | void log_buf_vmcoreinfo_setup(void) |
04d491ab | 997 | { |
74caba7f JO |
998 | struct dev_printk_info *dev_info = NULL; |
999 | ||
896fbe20 JO |
1000 | VMCOREINFO_SYMBOL(prb); |
1001 | VMCOREINFO_SYMBOL(printk_rb_static); | |
1002 | VMCOREINFO_SYMBOL(clear_seq); | |
1003 | ||
6791457a | 1004 | /* |
896fbe20 | 1005 | * Export struct size and field offsets. User space tools can |
6791457a VG |
1006 | * parse it and detect any changes to structure down the line. |
1007 | */ | |
896fbe20 JO |
1008 | |
1009 | VMCOREINFO_STRUCT_SIZE(printk_ringbuffer); | |
1010 | VMCOREINFO_OFFSET(printk_ringbuffer, desc_ring); | |
1011 | VMCOREINFO_OFFSET(printk_ringbuffer, text_data_ring); | |
896fbe20 JO |
1012 | VMCOREINFO_OFFSET(printk_ringbuffer, fail); |
1013 | ||
1014 | VMCOREINFO_STRUCT_SIZE(prb_desc_ring); | |
1015 | VMCOREINFO_OFFSET(prb_desc_ring, count_bits); | |
1016 | VMCOREINFO_OFFSET(prb_desc_ring, descs); | |
cfe2790b | 1017 | VMCOREINFO_OFFSET(prb_desc_ring, infos); |
896fbe20 JO |
1018 | VMCOREINFO_OFFSET(prb_desc_ring, head_id); |
1019 | VMCOREINFO_OFFSET(prb_desc_ring, tail_id); | |
1020 | ||
1021 | VMCOREINFO_STRUCT_SIZE(prb_desc); | |
896fbe20 JO |
1022 | VMCOREINFO_OFFSET(prb_desc, state_var); |
1023 | VMCOREINFO_OFFSET(prb_desc, text_blk_lpos); | |
896fbe20 JO |
1024 | |
1025 | VMCOREINFO_STRUCT_SIZE(prb_data_blk_lpos); | |
1026 | VMCOREINFO_OFFSET(prb_data_blk_lpos, begin); | |
1027 | VMCOREINFO_OFFSET(prb_data_blk_lpos, next); | |
1028 | ||
1029 | VMCOREINFO_STRUCT_SIZE(printk_info); | |
1030 | VMCOREINFO_OFFSET(printk_info, seq); | |
1031 | VMCOREINFO_OFFSET(printk_info, ts_nsec); | |
1032 | VMCOREINFO_OFFSET(printk_info, text_len); | |
896fbe20 | 1033 | VMCOREINFO_OFFSET(printk_info, caller_id); |
74caba7f JO |
1034 | VMCOREINFO_OFFSET(printk_info, dev_info); |
1035 | ||
1036 | VMCOREINFO_STRUCT_SIZE(dev_printk_info); | |
1037 | VMCOREINFO_OFFSET(dev_printk_info, subsystem); | |
1038 | VMCOREINFO_LENGTH(printk_info_subsystem, sizeof(dev_info->subsystem)); | |
1039 | VMCOREINFO_OFFSET(dev_printk_info, device); | |
1040 | VMCOREINFO_LENGTH(printk_info_device, sizeof(dev_info->device)); | |
896fbe20 JO |
1041 | |
1042 | VMCOREINFO_STRUCT_SIZE(prb_data_ring); | |
1043 | VMCOREINFO_OFFSET(prb_data_ring, size_bits); | |
1044 | VMCOREINFO_OFFSET(prb_data_ring, data); | |
1045 | VMCOREINFO_OFFSET(prb_data_ring, head_lpos); | |
1046 | VMCOREINFO_OFFSET(prb_data_ring, tail_lpos); | |
1047 | ||
1048 | VMCOREINFO_SIZE(atomic_long_t); | |
1049 | VMCOREINFO_TYPE_OFFSET(atomic_long_t, counter); | |
7d7a23a9 JO |
1050 | |
1051 | VMCOREINFO_STRUCT_SIZE(latched_seq); | |
1052 | VMCOREINFO_OFFSET(latched_seq, val); | |
04d491ab NH |
1053 | } |
1054 | #endif | |
1055 | ||
162a7e75 MT |
1056 | /* requested log_buf_len from kernel cmdline */ |
1057 | static unsigned long __initdata new_log_buf_len; | |
1058 | ||
c0a318a3 | 1059 | /* we practice scaling the ring buffer by powers of 2 */ |
e6fe3e5b | 1060 | static void __init log_buf_len_update(u64 size) |
1da177e4 | 1061 | { |
e6fe3e5b HZ |
1062 | if (size > (u64)LOG_BUF_LEN_MAX) { |
1063 | size = (u64)LOG_BUF_LEN_MAX; | |
1064 | pr_err("log_buf over 2G is not supported.\n"); | |
1065 | } | |
1066 | ||
1da177e4 LT |
1067 | if (size) |
1068 | size = roundup_pow_of_two(size); | |
162a7e75 | 1069 | if (size > log_buf_len) |
e6fe3e5b | 1070 | new_log_buf_len = (unsigned long)size; |
c0a318a3 LR |
1071 | } |
1072 | ||
1073 | /* save requested log_buf_len since it's too early to process it */ | |
1074 | static int __init log_buf_len_setup(char *str) | |
1075 | { | |
e6fe3e5b | 1076 | u64 size; |
277fcdb2 HZ |
1077 | |
1078 | if (!str) | |
1079 | return -EINVAL; | |
1080 | ||
1081 | size = memparse(str, &str); | |
c0a318a3 LR |
1082 | |
1083 | log_buf_len_update(size); | |
162a7e75 MT |
1084 | |
1085 | return 0; | |
1da177e4 | 1086 | } |
162a7e75 MT |
1087 | early_param("log_buf_len", log_buf_len_setup); |
1088 | ||
2240a31d GU |
1089 | #ifdef CONFIG_SMP |
1090 | #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) | |
1091 | ||
23b2899f LR |
1092 | static void __init log_buf_add_cpu(void) |
1093 | { | |
1094 | unsigned int cpu_extra; | |
1095 | ||
1096 | /* | |
1097 | * archs should set up cpu_possible_bits properly with | |
1098 | * set_cpu_possible() after setup_arch() but just in | |
1099 | * case lets ensure this is valid. | |
1100 | */ | |
1101 | if (num_possible_cpus() == 1) | |
1102 | return; | |
1103 | ||
1104 | cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; | |
1105 | ||
1106 | /* by default this will only continue through for large > 64 CPUs */ | |
1107 | if (cpu_extra <= __LOG_BUF_LEN / 2) | |
1108 | return; | |
1109 | ||
1110 | pr_info("log_buf_len individual max cpu contribution: %d bytes\n", | |
1111 | __LOG_CPU_MAX_BUF_LEN); | |
1112 | pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", | |
1113 | cpu_extra); | |
1114 | pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); | |
1115 | ||
1116 | log_buf_len_update(cpu_extra + __LOG_BUF_LEN); | |
1117 | } | |
2240a31d GU |
1118 | #else /* !CONFIG_SMP */ |
1119 | static inline void log_buf_add_cpu(void) {} | |
1120 | #endif /* CONFIG_SMP */ | |
23b2899f | 1121 | |
ab6f762f SS |
1122 | static void __init set_percpu_data_ready(void) |
1123 | { | |
ab6f762f SS |
1124 | __printk_percpu_data_ready = true; |
1125 | } | |
1126 | ||
896fbe20 JO |
1127 | static unsigned int __init add_to_rb(struct printk_ringbuffer *rb, |
1128 | struct printk_record *r) | |
1129 | { | |
1130 | struct prb_reserved_entry e; | |
1131 | struct printk_record dest_r; | |
1132 | ||
f35efc78 | 1133 | prb_rec_init_wr(&dest_r, r->info->text_len); |
896fbe20 JO |
1134 | |
1135 | if (!prb_reserve(&e, rb, &dest_r)) | |
1136 | return 0; | |
1137 | ||
cc5c7041 JO |
1138 | memcpy(&dest_r.text_buf[0], &r->text_buf[0], r->info->text_len); |
1139 | dest_r.info->text_len = r->info->text_len; | |
896fbe20 JO |
1140 | dest_r.info->facility = r->info->facility; |
1141 | dest_r.info->level = r->info->level; | |
1142 | dest_r.info->flags = r->info->flags; | |
1143 | dest_r.info->ts_nsec = r->info->ts_nsec; | |
1144 | dest_r.info->caller_id = r->info->caller_id; | |
74caba7f | 1145 | memcpy(&dest_r.info->dev_info, &r->info->dev_info, sizeof(dest_r.info->dev_info)); |
896fbe20 | 1146 | |
f5f022e5 | 1147 | prb_final_commit(&e); |
896fbe20 JO |
1148 | |
1149 | return prb_record_text_space(&e); | |
1150 | } | |
1151 | ||
0463d04e | 1152 | static char setup_text_buf[LOG_LINE_MAX] __initdata; |
896fbe20 | 1153 | |
162a7e75 MT |
1154 | void __init setup_log_buf(int early) |
1155 | { | |
cfe2790b | 1156 | struct printk_info *new_infos; |
896fbe20 JO |
1157 | unsigned int new_descs_count; |
1158 | struct prb_desc *new_descs; | |
1159 | struct printk_info info; | |
1160 | struct printk_record r; | |
93d102f0 | 1161 | unsigned int text_size; |
896fbe20 | 1162 | size_t new_descs_size; |
cfe2790b | 1163 | size_t new_infos_size; |
162a7e75 | 1164 | unsigned long flags; |
162a7e75 | 1165 | char *new_log_buf; |
d2130e82 | 1166 | unsigned int free; |
896fbe20 | 1167 | u64 seq; |
162a7e75 | 1168 | |
ab6f762f SS |
1169 | /* |
1170 | * Some archs call setup_log_buf() multiple times - first is very | |
1171 | * early, e.g. from setup_arch(), and second - when percpu_areas | |
1172 | * are initialised. | |
1173 | */ | |
1174 | if (!early) | |
1175 | set_percpu_data_ready(); | |
1176 | ||
23b2899f LR |
1177 | if (log_buf != __log_buf) |
1178 | return; | |
1179 | ||
1180 | if (!early && !new_log_buf_len) | |
1181 | log_buf_add_cpu(); | |
1182 | ||
162a7e75 MT |
1183 | if (!new_log_buf_len) |
1184 | return; | |
1da177e4 | 1185 | |
896fbe20 JO |
1186 | new_descs_count = new_log_buf_len >> PRB_AVGBITS; |
1187 | if (new_descs_count == 0) { | |
1188 | pr_err("new_log_buf_len: %lu too small\n", new_log_buf_len); | |
1189 | return; | |
1190 | } | |
1191 | ||
26fb3dae | 1192 | new_log_buf = memblock_alloc(new_log_buf_len, LOG_ALIGN); |
162a7e75 | 1193 | if (unlikely(!new_log_buf)) { |
896fbe20 JO |
1194 | pr_err("log_buf_len: %lu text bytes not available\n", |
1195 | new_log_buf_len); | |
162a7e75 MT |
1196 | return; |
1197 | } | |
1198 | ||
896fbe20 JO |
1199 | new_descs_size = new_descs_count * sizeof(struct prb_desc); |
1200 | new_descs = memblock_alloc(new_descs_size, LOG_ALIGN); | |
1201 | if (unlikely(!new_descs)) { | |
1202 | pr_err("log_buf_len: %zu desc bytes not available\n", | |
1203 | new_descs_size); | |
f35efc78 | 1204 | goto err_free_log_buf; |
cfe2790b JO |
1205 | } |
1206 | ||
1207 | new_infos_size = new_descs_count * sizeof(struct printk_info); | |
1208 | new_infos = memblock_alloc(new_infos_size, LOG_ALIGN); | |
1209 | if (unlikely(!new_infos)) { | |
1210 | pr_err("log_buf_len: %zu info bytes not available\n", | |
1211 | new_infos_size); | |
1212 | goto err_free_descs; | |
896fbe20 JO |
1213 | } |
1214 | ||
f35efc78 | 1215 | prb_rec_init_rd(&r, &info, &setup_text_buf[0], sizeof(setup_text_buf)); |
896fbe20 JO |
1216 | |
1217 | prb_init(&printk_rb_dynamic, | |
1218 | new_log_buf, ilog2(new_log_buf_len), | |
cfe2790b JO |
1219 | new_descs, ilog2(new_descs_count), |
1220 | new_infos); | |
896fbe20 | 1221 | |
93d102f0 | 1222 | local_irq_save(flags); |
896fbe20 | 1223 | |
162a7e75 MT |
1224 | log_buf_len = new_log_buf_len; |
1225 | log_buf = new_log_buf; | |
1226 | new_log_buf_len = 0; | |
896fbe20 JO |
1227 | |
1228 | free = __LOG_BUF_LEN; | |
93d102f0 JO |
1229 | prb_for_each_record(0, &printk_rb_static, seq, &r) { |
1230 | text_size = add_to_rb(&printk_rb_dynamic, &r); | |
1231 | if (text_size > free) | |
1232 | free = 0; | |
1233 | else | |
1234 | free -= text_size; | |
1235 | } | |
896fbe20 | 1236 | |
896fbe20 JO |
1237 | prb = &printk_rb_dynamic; |
1238 | ||
93d102f0 JO |
1239 | local_irq_restore(flags); |
1240 | ||
1241 | /* | |
1242 | * Copy any remaining messages that might have appeared from | |
1243 | * NMI context after copying but before switching to the | |
1244 | * dynamic buffer. | |
1245 | */ | |
1246 | prb_for_each_record(seq, &printk_rb_static, seq, &r) { | |
1247 | text_size = add_to_rb(&printk_rb_dynamic, &r); | |
1248 | if (text_size > free) | |
1249 | free = 0; | |
1250 | else | |
1251 | free -= text_size; | |
1252 | } | |
162a7e75 | 1253 | |
896fbe20 JO |
1254 | if (seq != prb_next_seq(&printk_rb_static)) { |
1255 | pr_err("dropped %llu messages\n", | |
1256 | prb_next_seq(&printk_rb_static) - seq); | |
1257 | } | |
1258 | ||
e6fe3e5b HZ |
1259 | pr_info("log_buf_len: %u bytes\n", log_buf_len); |
1260 | pr_info("early log buf free: %u(%u%%)\n", | |
162a7e75 | 1261 | free, (free * 100) / __LOG_BUF_LEN); |
cfe2790b JO |
1262 | return; |
1263 | ||
1264 | err_free_descs: | |
4421cca0 | 1265 | memblock_free(new_descs, new_descs_size); |
cfe2790b | 1266 | err_free_log_buf: |
4421cca0 | 1267 | memblock_free(new_log_buf, new_log_buf_len); |
162a7e75 | 1268 | } |
1da177e4 | 1269 | |
2fa72c8f AC |
1270 | static bool __read_mostly ignore_loglevel; |
1271 | ||
1272 | static int __init ignore_loglevel_setup(char *str) | |
1273 | { | |
d25d9fec | 1274 | ignore_loglevel = true; |
27083bac | 1275 | pr_info("debug: ignoring loglevel setting.\n"); |
2fa72c8f AC |
1276 | |
1277 | return 0; | |
1278 | } | |
1279 | ||
1280 | early_param("ignore_loglevel", ignore_loglevel_setup); | |
1281 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); | |
205bd3d2 JP |
1282 | MODULE_PARM_DESC(ignore_loglevel, |
1283 | "ignore loglevel setting (prints all kernel messages to the console)"); | |
2fa72c8f | 1284 | |
cf775444 SS |
1285 | static bool suppress_message_printing(int level) |
1286 | { | |
1287 | return (level >= console_loglevel && !ignore_loglevel); | |
1288 | } | |
1289 | ||
bfe8df3d RD |
1290 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
1291 | ||
674dff65 | 1292 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 1293 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
1294 | |
1295 | static int __init boot_delay_setup(char *str) | |
1296 | { | |
1297 | unsigned long lpj; | |
bfe8df3d RD |
1298 | |
1299 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
1300 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
1301 | ||
1302 | get_option(&str, &boot_delay); | |
1303 | if (boot_delay > 10 * 1000) | |
1304 | boot_delay = 0; | |
1305 | ||
3a3b6ed2 DY |
1306 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
1307 | "HZ: %d, loops_per_msec: %llu\n", | |
1308 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
29e9d225 | 1309 | return 0; |
bfe8df3d | 1310 | } |
29e9d225 | 1311 | early_param("boot_delay", boot_delay_setup); |
bfe8df3d | 1312 | |
2fa72c8f | 1313 | static void boot_delay_msec(int level) |
bfe8df3d RD |
1314 | { |
1315 | unsigned long long k; | |
1316 | unsigned long timeout; | |
1317 | ||
ff48cd26 | 1318 | if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING) |
cf775444 | 1319 | || suppress_message_printing(level)) { |
bfe8df3d | 1320 | return; |
2fa72c8f | 1321 | } |
bfe8df3d | 1322 | |
3a3b6ed2 | 1323 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
1324 | |
1325 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
1326 | while (k) { | |
1327 | k--; | |
1328 | cpu_relax(); | |
1329 | /* | |
1330 | * use (volatile) jiffies to prevent | |
1331 | * compiler reduction; loop termination via jiffies | |
1332 | * is secondary and may or may not happen. | |
1333 | */ | |
1334 | if (time_after(jiffies, timeout)) | |
1335 | break; | |
1336 | touch_nmi_watchdog(); | |
1337 | } | |
1338 | } | |
1339 | #else | |
2fa72c8f | 1340 | static inline void boot_delay_msec(int level) |
bfe8df3d RD |
1341 | { |
1342 | } | |
1343 | #endif | |
1344 | ||
e99aa461 | 1345 | static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); |
7ff9554b KS |
1346 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1347 | ||
07c17732 | 1348 | static size_t print_syslog(unsigned int level, char *buf) |
084681d1 | 1349 | { |
07c17732 TH |
1350 | return sprintf(buf, "<%u>", level); |
1351 | } | |
35dac27c | 1352 | |
084681d1 KS |
1353 | static size_t print_time(u64 ts, char *buf) |
1354 | { | |
e80c1a9d | 1355 | unsigned long rem_nsec = do_div(ts, 1000000000); |
084681d1 | 1356 | |
15ff2069 | 1357 | return sprintf(buf, "[%5lu.%06lu]", |
084681d1 KS |
1358 | (unsigned long)ts, rem_nsec / 1000); |
1359 | } | |
1360 | ||
15ff2069 TH |
1361 | #ifdef CONFIG_PRINTK_CALLER |
1362 | static size_t print_caller(u32 id, char *buf) | |
1363 | { | |
1364 | char caller[12]; | |
1365 | ||
1366 | snprintf(caller, sizeof(caller), "%c%u", | |
1367 | id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); | |
1368 | return sprintf(buf, "[%6s]", caller); | |
1369 | } | |
1370 | #else | |
1371 | #define print_caller(id, buf) 0 | |
1372 | #endif | |
1373 | ||
896fbe20 JO |
1374 | static size_t info_print_prefix(const struct printk_info *info, bool syslog, |
1375 | bool time, char *buf) | |
649e6ee3 | 1376 | { |
3ce9a7c0 | 1377 | size_t len = 0; |
649e6ee3 | 1378 | |
07c17732 | 1379 | if (syslog) |
896fbe20 | 1380 | len = print_syslog((info->facility << 3) | info->level, buf); |
15ff2069 | 1381 | |
e80c1a9d | 1382 | if (time) |
896fbe20 | 1383 | len += print_time(info->ts_nsec, buf + len); |
15ff2069 | 1384 | |
896fbe20 | 1385 | len += print_caller(info->caller_id, buf + len); |
15ff2069 TH |
1386 | |
1387 | if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) { | |
1388 | buf[len++] = ' '; | |
1389 | buf[len] = '\0'; | |
1390 | } | |
1391 | ||
3ce9a7c0 | 1392 | return len; |
649e6ee3 KS |
1393 | } |
1394 | ||
896fbe20 JO |
1395 | /* |
1396 | * Prepare the record for printing. The text is shifted within the given | |
1397 | * buffer to avoid a need for another one. The following operations are | |
1398 | * done: | |
1399 | * | |
1400 | * - Add prefix for each line. | |
f0e386ee | 1401 | * - Drop truncated lines that no longer fit into the buffer. |
896fbe20 | 1402 | * - Add the trailing newline that has been removed in vprintk_store(). |
f0e386ee JO |
1403 | * - Add a string terminator. |
1404 | * | |
1405 | * Since the produced string is always terminated, the maximum possible | |
1406 | * return value is @r->text_buf_size - 1; | |
896fbe20 JO |
1407 | * |
1408 | * Return: The length of the updated/prepared text, including the added | |
f0e386ee JO |
1409 | * prefixes and the newline. The terminator is not counted. The dropped |
1410 | * line(s) are not counted. | |
896fbe20 JO |
1411 | */ |
1412 | static size_t record_print_text(struct printk_record *r, bool syslog, | |
1413 | bool time) | |
7ff9554b | 1414 | { |
896fbe20 JO |
1415 | size_t text_len = r->info->text_len; |
1416 | size_t buf_size = r->text_buf_size; | |
1417 | char *text = r->text_buf; | |
07c17732 | 1418 | char prefix[PREFIX_MAX]; |
896fbe20 JO |
1419 | bool truncated = false; |
1420 | size_t prefix_len; | |
1421 | size_t line_len; | |
1422 | size_t len = 0; | |
1423 | char *next; | |
3ce9a7c0 | 1424 | |
59f8bcca JO |
1425 | /* |
1426 | * If the message was truncated because the buffer was not large | |
1427 | * enough, treat the available text as if it were the full text. | |
1428 | */ | |
1429 | if (text_len > buf_size) | |
1430 | text_len = buf_size; | |
3ce9a7c0 | 1431 | |
896fbe20 | 1432 | prefix_len = info_print_prefix(r->info, syslog, time, prefix); |
3ce9a7c0 | 1433 | |
896fbe20 JO |
1434 | /* |
1435 | * @text_len: bytes of unprocessed text | |
1436 | * @line_len: bytes of current line _without_ newline | |
1437 | * @text: pointer to beginning of current line | |
1438 | * @len: number of bytes prepared in r->text_buf | |
1439 | */ | |
1440 | for (;;) { | |
1441 | next = memchr(text, '\n', text_len); | |
3ce9a7c0 | 1442 | if (next) { |
896fbe20 | 1443 | line_len = next - text; |
3ce9a7c0 | 1444 | } else { |
896fbe20 JO |
1445 | /* Drop truncated line(s). */ |
1446 | if (truncated) | |
1447 | break; | |
1448 | line_len = text_len; | |
3ce9a7c0 | 1449 | } |
7ff9554b | 1450 | |
896fbe20 JO |
1451 | /* |
1452 | * Truncate the text if there is not enough space to add the | |
f0e386ee | 1453 | * prefix and a trailing newline and a terminator. |
896fbe20 | 1454 | */ |
f0e386ee | 1455 | if (len + prefix_len + text_len + 1 + 1 > buf_size) { |
896fbe20 | 1456 | /* Drop even the current line if no space. */ |
f0e386ee | 1457 | if (len + prefix_len + line_len + 1 + 1 > buf_size) |
3ce9a7c0 | 1458 | break; |
7ff9554b | 1459 | |
f0e386ee | 1460 | text_len = buf_size - len - prefix_len - 1 - 1; |
896fbe20 | 1461 | truncated = true; |
3ce9a7c0 | 1462 | } |
7ff9554b | 1463 | |
896fbe20 JO |
1464 | memmove(text + prefix_len, text, text_len); |
1465 | memcpy(text, prefix, prefix_len); | |
1466 | ||
f0e386ee JO |
1467 | /* |
1468 | * Increment the prepared length to include the text and | |
1469 | * prefix that were just moved+copied. Also increment for the | |
1470 | * newline at the end of this line. If this is the last line, | |
1471 | * there is no newline, but it will be added immediately below. | |
1472 | */ | |
896fbe20 | 1473 | len += prefix_len + line_len + 1; |
896fbe20 JO |
1474 | if (text_len == line_len) { |
1475 | /* | |
f0e386ee JO |
1476 | * This is the last line. Add the trailing newline |
1477 | * removed in vprintk_store(). | |
896fbe20 JO |
1478 | */ |
1479 | text[prefix_len + line_len] = '\n'; | |
1480 | break; | |
1481 | } | |
1482 | ||
1483 | /* | |
1484 | * Advance beyond the added prefix and the related line with | |
1485 | * its newline. | |
1486 | */ | |
1487 | text += prefix_len + line_len + 1; | |
1488 | ||
1489 | /* | |
1490 | * The remaining text has only decreased by the line with its | |
1491 | * newline. | |
1492 | * | |
1493 | * Note that @text_len can become zero. It happens when @text | |
1494 | * ended with a newline (either due to truncation or the | |
1495 | * original string ending with "\n\n"). The loop is correctly | |
1496 | * repeated and (if not truncated) an empty line with a prefix | |
1497 | * will be prepared. | |
1498 | */ | |
1499 | text_len -= line_len + 1; | |
1500 | } | |
7ff9554b | 1501 | |
f0e386ee JO |
1502 | /* |
1503 | * If a buffer was provided, it will be terminated. Space for the | |
1504 | * string terminator is guaranteed to be available. The terminator is | |
1505 | * not counted in the return value. | |
1506 | */ | |
1507 | if (buf_size > 0) | |
08d60e59 | 1508 | r->text_buf[len] = 0; |
f0e386ee | 1509 | |
7ff9554b KS |
1510 | return len; |
1511 | } | |
1512 | ||
896fbe20 JO |
1513 | static size_t get_record_print_text_size(struct printk_info *info, |
1514 | unsigned int line_count, | |
1515 | bool syslog, bool time) | |
1516 | { | |
1517 | char prefix[PREFIX_MAX]; | |
1518 | size_t prefix_len; | |
1519 | ||
1520 | prefix_len = info_print_prefix(info, syslog, time, prefix); | |
1521 | ||
1522 | /* | |
1523 | * Each line will be preceded with a prefix. The intermediate | |
1524 | * newlines are already within the text, but a final trailing | |
1525 | * newline will be added. | |
1526 | */ | |
1527 | return ((prefix_len * line_count) + info->text_len + 1); | |
1528 | } | |
1529 | ||
4260e0e5 JO |
1530 | /* |
1531 | * Beginning with @start_seq, find the first record where it and all following | |
1532 | * records up to (but not including) @max_seq fit into @size. | |
1533 | * | |
1534 | * @max_seq is simply an upper bound and does not need to exist. If the caller | |
1535 | * does not require an upper bound, -1 can be used for @max_seq. | |
1536 | */ | |
1537 | static u64 find_first_fitting_seq(u64 start_seq, u64 max_seq, size_t size, | |
1538 | bool syslog, bool time) | |
1539 | { | |
1540 | struct printk_info info; | |
1541 | unsigned int line_count; | |
1542 | size_t len = 0; | |
1543 | u64 seq; | |
1544 | ||
1545 | /* Determine the size of the records up to @max_seq. */ | |
1546 | prb_for_each_info(start_seq, prb, seq, &info, &line_count) { | |
1547 | if (info.seq >= max_seq) | |
1548 | break; | |
1549 | len += get_record_print_text_size(&info, line_count, syslog, time); | |
1550 | } | |
1551 | ||
1552 | /* | |
1553 | * Adjust the upper bound for the next loop to avoid subtracting | |
1554 | * lengths that were never added. | |
1555 | */ | |
1556 | if (seq < max_seq) | |
1557 | max_seq = seq; | |
1558 | ||
1559 | /* | |
1560 | * Move first record forward until length fits into the buffer. Ignore | |
1561 | * newest messages that were not counted in the above cycle. Messages | |
1562 | * might appear and get lost in the meantime. This is a best effort | |
1563 | * that prevents an infinite loop that could occur with a retry. | |
1564 | */ | |
1565 | prb_for_each_info(start_seq, prb, seq, &info, &line_count) { | |
1566 | if (len <= size || info.seq >= max_seq) | |
1567 | break; | |
1568 | len -= get_record_print_text_size(&info, line_count, syslog, time); | |
1569 | } | |
1570 | ||
1571 | return seq; | |
1572 | } | |
1573 | ||
8d909b23 | 1574 | /* The caller is responsible for making sure @size is greater than 0. */ |
7ff9554b KS |
1575 | static int syslog_print(char __user *buf, int size) |
1576 | { | |
896fbe20 JO |
1577 | struct printk_info info; |
1578 | struct printk_record r; | |
7ff9554b | 1579 | char *text; |
116e90b2 | 1580 | int len = 0; |
8d909b23 | 1581 | u64 seq; |
7ff9554b | 1582 | |
cf5b0208 | 1583 | text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL); |
7ff9554b KS |
1584 | if (!text) |
1585 | return -ENOMEM; | |
1586 | ||
cf5b0208 | 1587 | prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX); |
896fbe20 | 1588 | |
8d909b23 JO |
1589 | mutex_lock(&syslog_lock); |
1590 | ||
1591 | /* | |
1592 | * Wait for the @syslog_seq record to be available. @syslog_seq may | |
1593 | * change while waiting. | |
1594 | */ | |
1595 | do { | |
1596 | seq = syslog_seq; | |
1597 | ||
1598 | mutex_unlock(&syslog_lock); | |
1f5d7830 JO |
1599 | /* |
1600 | * Guarantee this task is visible on the waitqueue before | |
1601 | * checking the wake condition. | |
1602 | * | |
1603 | * The full memory barrier within set_current_state() of | |
1604 | * prepare_to_wait_event() pairs with the full memory barrier | |
1605 | * within wq_has_sleeper(). | |
1606 | * | |
5341b93d | 1607 | * This pairs with __wake_up_klogd:A. |
1f5d7830 JO |
1608 | */ |
1609 | len = wait_event_interruptible(log_wait, | |
1610 | prb_read_valid(prb, seq, NULL)); /* LMM(syslog_print:A) */ | |
8d909b23 JO |
1611 | mutex_lock(&syslog_lock); |
1612 | ||
1613 | if (len) | |
1614 | goto out; | |
1615 | } while (syslog_seq != seq); | |
1616 | ||
1617 | /* | |
1618 | * Copy records that fit into the buffer. The above cycle makes sure | |
1619 | * that the first record is always available. | |
1620 | */ | |
1621 | do { | |
116e90b2 | 1622 | size_t n; |
eb02dac9 | 1623 | size_t skip; |
8d909b23 | 1624 | int err; |
116e90b2 | 1625 | |
8d909b23 | 1626 | if (!prb_read_valid(prb, syslog_seq, &r)) |
116e90b2 | 1627 | break; |
8d909b23 | 1628 | |
896fbe20 JO |
1629 | if (r.info->seq != syslog_seq) { |
1630 | /* message is gone, move to next valid one */ | |
1631 | syslog_seq = r.info->seq; | |
1632 | syslog_partial = 0; | |
1633 | } | |
eb02dac9 | 1634 | |
e80c1a9d TH |
1635 | /* |
1636 | * To keep reading/counting partial line consistent, | |
1637 | * use printk_time value as of the beginning of a line. | |
1638 | */ | |
1639 | if (!syslog_partial) | |
1640 | syslog_time = printk_time; | |
1641 | ||
eb02dac9 | 1642 | skip = syslog_partial; |
896fbe20 | 1643 | n = record_print_text(&r, true, syslog_time); |
eb02dac9 KS |
1644 | if (n - syslog_partial <= size) { |
1645 | /* message fits into buffer, move forward */ | |
896fbe20 | 1646 | syslog_seq = r.info->seq + 1; |
eb02dac9 KS |
1647 | n -= syslog_partial; |
1648 | syslog_partial = 0; | |
1649 | } else if (!len){ | |
1650 | /* partial read(), remember position */ | |
1651 | n = size; | |
1652 | syslog_partial += n; | |
116e90b2 JB |
1653 | } else |
1654 | n = 0; | |
116e90b2 JB |
1655 | |
1656 | if (!n) | |
1657 | break; | |
1658 | ||
8d909b23 JO |
1659 | mutex_unlock(&syslog_lock); |
1660 | err = copy_to_user(buf, text + skip, n); | |
1661 | mutex_lock(&syslog_lock); | |
1662 | ||
1663 | if (err) { | |
116e90b2 JB |
1664 | if (!len) |
1665 | len = -EFAULT; | |
1666 | break; | |
1667 | } | |
eb02dac9 KS |
1668 | |
1669 | len += n; | |
1670 | size -= n; | |
1671 | buf += n; | |
8d909b23 JO |
1672 | } while (size); |
1673 | out: | |
1674 | mutex_unlock(&syslog_lock); | |
7ff9554b KS |
1675 | kfree(text); |
1676 | return len; | |
1677 | } | |
1678 | ||
1679 | static int syslog_print_all(char __user *buf, int size, bool clear) | |
1680 | { | |
896fbe20 | 1681 | struct printk_info info; |
896fbe20 | 1682 | struct printk_record r; |
7ff9554b KS |
1683 | char *text; |
1684 | int len = 0; | |
63842c21 | 1685 | u64 seq; |
e80c1a9d | 1686 | bool time; |
63842c21 | 1687 | |
cf5b0208 | 1688 | text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL); |
7ff9554b KS |
1689 | if (!text) |
1690 | return -ENOMEM; | |
1691 | ||
e80c1a9d | 1692 | time = printk_time; |
63842c21 NG |
1693 | /* |
1694 | * Find first record that fits, including all following records, | |
1695 | * into the user-provided buffer for this dump. | |
1696 | */ | |
7d7a23a9 JO |
1697 | seq = find_first_fitting_seq(latched_seq_read_nolock(&clear_seq), -1, |
1698 | size, true, time); | |
7ff9554b | 1699 | |
cf5b0208 | 1700 | prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX); |
7ff9554b | 1701 | |
63842c21 | 1702 | len = 0; |
896fbe20 JO |
1703 | prb_for_each_record(seq, prb, seq, &r) { |
1704 | int textlen; | |
7ff9554b | 1705 | |
896fbe20 JO |
1706 | textlen = record_print_text(&r, true, time); |
1707 | ||
1708 | if (len + textlen > size) { | |
1709 | seq--; | |
1710 | break; | |
1711 | } | |
7ff9554b | 1712 | |
63842c21 NG |
1713 | if (copy_to_user(buf + len, text, textlen)) |
1714 | len = -EFAULT; | |
1715 | else | |
1716 | len += textlen; | |
7ff9554b | 1717 | |
896fbe20 JO |
1718 | if (len < 0) |
1719 | break; | |
7ff9554b KS |
1720 | } |
1721 | ||
636babdc | 1722 | if (clear) { |
b371cbb5 | 1723 | mutex_lock(&syslog_lock); |
7d7a23a9 | 1724 | latched_seq_write(&clear_seq, seq); |
b371cbb5 | 1725 | mutex_unlock(&syslog_lock); |
636babdc | 1726 | } |
7ff9554b KS |
1727 | |
1728 | kfree(text); | |
1729 | return len; | |
1730 | } | |
1731 | ||
8599dc7d PM |
1732 | static void syslog_clear(void) |
1733 | { | |
b371cbb5 | 1734 | mutex_lock(&syslog_lock); |
7d7a23a9 | 1735 | latched_seq_write(&clear_seq, prb_next_seq(prb)); |
b371cbb5 | 1736 | mutex_unlock(&syslog_lock); |
636babdc JO |
1737 | } |
1738 | ||
3ea4331c | 1739 | int do_syslog(int type, char __user *buf, int len, int source) |
1da177e4 | 1740 | { |
13791c80 | 1741 | struct printk_info info; |
7ff9554b | 1742 | bool clear = false; |
a39d4a85 | 1743 | static int saved_console_loglevel = LOGLEVEL_DEFAULT; |
ee24aebf | 1744 | int error; |
1da177e4 | 1745 | |
3ea4331c | 1746 | error = check_syslog_permissions(type, source); |
ee24aebf | 1747 | if (error) |
077a1cc0 | 1748 | return error; |
12b3052c | 1749 | |
1da177e4 | 1750 | switch (type) { |
d78ca3cd | 1751 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 1752 | break; |
d78ca3cd | 1753 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 1754 | break; |
d78ca3cd | 1755 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 | 1756 | if (!buf || len < 0) |
077a1cc0 | 1757 | return -EINVAL; |
1da177e4 | 1758 | if (!len) |
077a1cc0 | 1759 | return 0; |
96d4f267 | 1760 | if (!access_ok(buf, len)) |
077a1cc0 | 1761 | return -EFAULT; |
7ff9554b | 1762 | error = syslog_print(buf, len); |
1da177e4 | 1763 | break; |
d78ca3cd KC |
1764 | /* Read/clear last kernel messages */ |
1765 | case SYSLOG_ACTION_READ_CLEAR: | |
7ff9554b | 1766 | clear = true; |
4e797e6e | 1767 | fallthrough; |
d78ca3cd KC |
1768 | /* Read last kernel messages */ |
1769 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 | 1770 | if (!buf || len < 0) |
077a1cc0 | 1771 | return -EINVAL; |
1da177e4 | 1772 | if (!len) |
077a1cc0 | 1773 | return 0; |
96d4f267 | 1774 | if (!access_ok(buf, len)) |
077a1cc0 | 1775 | return -EFAULT; |
7ff9554b | 1776 | error = syslog_print_all(buf, len, clear); |
1da177e4 | 1777 | break; |
d78ca3cd KC |
1778 | /* Clear ring buffer */ |
1779 | case SYSLOG_ACTION_CLEAR: | |
8599dc7d | 1780 | syslog_clear(); |
4661e356 | 1781 | break; |
d78ca3cd KC |
1782 | /* Disable logging to console */ |
1783 | case SYSLOG_ACTION_CONSOLE_OFF: | |
a39d4a85 | 1784 | if (saved_console_loglevel == LOGLEVEL_DEFAULT) |
1aaad49e | 1785 | saved_console_loglevel = console_loglevel; |
1da177e4 LT |
1786 | console_loglevel = minimum_console_loglevel; |
1787 | break; | |
d78ca3cd KC |
1788 | /* Enable logging to console */ |
1789 | case SYSLOG_ACTION_CONSOLE_ON: | |
a39d4a85 | 1790 | if (saved_console_loglevel != LOGLEVEL_DEFAULT) { |
1aaad49e | 1791 | console_loglevel = saved_console_loglevel; |
a39d4a85 | 1792 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1aaad49e | 1793 | } |
1da177e4 | 1794 | break; |
d78ca3cd KC |
1795 | /* Set level of messages printed to console */ |
1796 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 | 1797 | if (len < 1 || len > 8) |
077a1cc0 | 1798 | return -EINVAL; |
1da177e4 LT |
1799 | if (len < minimum_console_loglevel) |
1800 | len = minimum_console_loglevel; | |
1801 | console_loglevel = len; | |
1aaad49e | 1802 | /* Implicitly re-enable logging to console */ |
a39d4a85 | 1803 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1da177e4 | 1804 | break; |
d78ca3cd KC |
1805 | /* Number of chars in the log buffer */ |
1806 | case SYSLOG_ACTION_SIZE_UNREAD: | |
b371cbb5 | 1807 | mutex_lock(&syslog_lock); |
13791c80 JO |
1808 | if (!prb_read_valid_info(prb, syslog_seq, &info, NULL)) { |
1809 | /* No unread messages. */ | |
b371cbb5 | 1810 | mutex_unlock(&syslog_lock); |
13791c80 JO |
1811 | return 0; |
1812 | } | |
1813 | if (info.seq != syslog_seq) { | |
7ff9554b | 1814 | /* messages are gone, move to first one */ |
13791c80 | 1815 | syslog_seq = info.seq; |
eb02dac9 | 1816 | syslog_partial = 0; |
7ff9554b | 1817 | } |
3ea4331c | 1818 | if (source == SYSLOG_FROM_PROC) { |
7ff9554b KS |
1819 | /* |
1820 | * Short-cut for poll(/"proc/kmsg") which simply checks | |
1821 | * for pending data, not the size; return the count of | |
1822 | * records, not the length. | |
1823 | */ | |
896fbe20 | 1824 | error = prb_next_seq(prb) - syslog_seq; |
7ff9554b | 1825 | } else { |
e80c1a9d | 1826 | bool time = syslog_partial ? syslog_time : printk_time; |
896fbe20 JO |
1827 | unsigned int line_count; |
1828 | u64 seq; | |
1829 | ||
1830 | prb_for_each_info(syslog_seq, prb, seq, &info, | |
1831 | &line_count) { | |
1832 | error += get_record_print_text_size(&info, line_count, | |
1833 | true, time); | |
e80c1a9d | 1834 | time = printk_time; |
7ff9554b | 1835 | } |
eb02dac9 | 1836 | error -= syslog_partial; |
7ff9554b | 1837 | } |
b371cbb5 | 1838 | mutex_unlock(&syslog_lock); |
1da177e4 | 1839 | break; |
d78ca3cd KC |
1840 | /* Size of the log buffer */ |
1841 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
1842 | error = log_buf_len; |
1843 | break; | |
1844 | default: | |
1845 | error = -EINVAL; | |
1846 | break; | |
1847 | } | |
077a1cc0 | 1848 | |
1da177e4 LT |
1849 | return error; |
1850 | } | |
1851 | ||
1e7bfb21 | 1852 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 1853 | { |
637241a9 | 1854 | return do_syslog(type, buf, len, SYSLOG_FROM_READER); |
1da177e4 LT |
1855 | } |
1856 | ||
c162d5b4 PM |
1857 | /* |
1858 | * Special console_lock variants that help to reduce the risk of soft-lockups. | |
1859 | * They allow to pass console_lock to another printk() call using a busy wait. | |
1860 | */ | |
1861 | ||
1862 | #ifdef CONFIG_LOCKDEP | |
1863 | static struct lockdep_map console_owner_dep_map = { | |
1864 | .name = "console_owner" | |
1865 | }; | |
1866 | #endif | |
1867 | ||
1868 | static DEFINE_RAW_SPINLOCK(console_owner_lock); | |
1869 | static struct task_struct *console_owner; | |
1870 | static bool console_waiter; | |
1871 | ||
1872 | /** | |
1873 | * console_lock_spinning_enable - mark beginning of code where another | |
1874 | * thread might safely busy wait | |
1875 | * | |
1876 | * This basically converts console_lock into a spinlock. This marks | |
1877 | * the section where the console_lock owner can not sleep, because | |
1878 | * there may be a waiter spinning (like a spinlock). Also it must be | |
1879 | * ready to hand over the lock at the end of the section. | |
1880 | */ | |
1881 | static void console_lock_spinning_enable(void) | |
1882 | { | |
1883 | raw_spin_lock(&console_owner_lock); | |
1884 | console_owner = current; | |
1885 | raw_spin_unlock(&console_owner_lock); | |
1886 | ||
1887 | /* The waiter may spin on us after setting console_owner */ | |
1888 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
1889 | } | |
1890 | ||
1891 | /** | |
1892 | * console_lock_spinning_disable_and_check - mark end of code where another | |
1893 | * thread was able to busy wait and check if there is a waiter | |
1894 | * | |
1895 | * This is called at the end of the section where spinning is allowed. | |
1896 | * It has two functions. First, it is a signal that it is no longer | |
1897 | * safe to start busy waiting for the lock. Second, it checks if | |
1898 | * there is a busy waiter and passes the lock rights to her. | |
1899 | * | |
fc956ae0 JO |
1900 | * Important: Callers lose both the console_lock and the SRCU read lock if |
1901 | * there was a busy waiter. They must not touch items synchronized by | |
1902 | * console_lock or SRCU read lock in this case. | |
c162d5b4 PM |
1903 | * |
1904 | * Return: 1 if the lock rights were passed, 0 otherwise. | |
1905 | */ | |
fc956ae0 | 1906 | static int console_lock_spinning_disable_and_check(int cookie) |
c162d5b4 PM |
1907 | { |
1908 | int waiter; | |
1909 | ||
1910 | raw_spin_lock(&console_owner_lock); | |
1911 | waiter = READ_ONCE(console_waiter); | |
1912 | console_owner = NULL; | |
1913 | raw_spin_unlock(&console_owner_lock); | |
1914 | ||
1915 | if (!waiter) { | |
5facae4f | 1916 | spin_release(&console_owner_dep_map, _THIS_IP_); |
c162d5b4 PM |
1917 | return 0; |
1918 | } | |
1919 | ||
1920 | /* The waiter is now free to continue */ | |
1921 | WRITE_ONCE(console_waiter, false); | |
1922 | ||
5facae4f | 1923 | spin_release(&console_owner_dep_map, _THIS_IP_); |
c162d5b4 | 1924 | |
fc956ae0 JO |
1925 | /* |
1926 | * Preserve lockdep lock ordering. Release the SRCU read lock before | |
1927 | * releasing the console_lock. | |
1928 | */ | |
1929 | console_srcu_read_unlock(cookie); | |
1930 | ||
c162d5b4 PM |
1931 | /* |
1932 | * Hand off console_lock to waiter. The waiter will perform | |
1933 | * the up(). After this, the waiter is the console_lock owner. | |
1934 | */ | |
5facae4f | 1935 | mutex_release(&console_lock_dep_map, _THIS_IP_); |
c162d5b4 PM |
1936 | return 1; |
1937 | } | |
1938 | ||
1939 | /** | |
1940 | * console_trylock_spinning - try to get console_lock by busy waiting | |
1941 | * | |
1942 | * This allows to busy wait for the console_lock when the current | |
1943 | * owner is running in specially marked sections. It means that | |
1944 | * the current owner is running and cannot reschedule until it | |
1945 | * is ready to lose the lock. | |
1946 | * | |
1947 | * Return: 1 if we got the lock, 0 othrewise | |
1948 | */ | |
1949 | static int console_trylock_spinning(void) | |
1950 | { | |
1951 | struct task_struct *owner = NULL; | |
1952 | bool waiter; | |
1953 | bool spin = false; | |
1954 | unsigned long flags; | |
1955 | ||
1956 | if (console_trylock()) | |
1957 | return 1; | |
1958 | ||
d5150709 SB |
1959 | /* |
1960 | * It's unsafe to spin once a panic has begun. If we are the | |
1961 | * panic CPU, we may have already halted the owner of the | |
1962 | * console_sem. If we are not the panic CPU, then we should | |
1963 | * avoid taking console_sem, so the panic CPU has a better | |
1964 | * chance of cleanly acquiring it later. | |
1965 | */ | |
1966 | if (panic_in_progress()) | |
1967 | return 0; | |
1968 | ||
c162d5b4 PM |
1969 | printk_safe_enter_irqsave(flags); |
1970 | ||
1971 | raw_spin_lock(&console_owner_lock); | |
1972 | owner = READ_ONCE(console_owner); | |
1973 | waiter = READ_ONCE(console_waiter); | |
1974 | if (!waiter && owner && owner != current) { | |
1975 | WRITE_ONCE(console_waiter, true); | |
1976 | spin = true; | |
1977 | } | |
1978 | raw_spin_unlock(&console_owner_lock); | |
1979 | ||
1980 | /* | |
1981 | * If there is an active printk() writing to the | |
1982 | * consoles, instead of having it write our data too, | |
1983 | * see if we can offload that load from the active | |
1984 | * printer, and do some printing ourselves. | |
1985 | * Go into a spin only if there isn't already a waiter | |
1986 | * spinning, and there is an active printer, and | |
1987 | * that active printer isn't us (recursive printk?). | |
1988 | */ | |
1989 | if (!spin) { | |
1990 | printk_safe_exit_irqrestore(flags); | |
1991 | return 0; | |
1992 | } | |
1993 | ||
1994 | /* We spin waiting for the owner to release us */ | |
1995 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
1996 | /* Owner will clear console_waiter on hand off */ | |
1997 | while (READ_ONCE(console_waiter)) | |
1998 | cpu_relax(); | |
5facae4f | 1999 | spin_release(&console_owner_dep_map, _THIS_IP_); |
c162d5b4 PM |
2000 | |
2001 | printk_safe_exit_irqrestore(flags); | |
2002 | /* | |
2003 | * The owner passed the console lock to us. | |
2004 | * Since we did not spin on console lock, annotate | |
2005 | * this as a trylock. Otherwise lockdep will | |
2006 | * complain. | |
2007 | */ | |
2008 | mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_); | |
2009 | ||
2010 | return 1; | |
2011 | } | |
2012 | ||
1da177e4 | 2013 | /* |
a699449b | 2014 | * Call the specified console driver, asking it to write out the specified |
03a749e6 | 2015 | * text and length. If @dropped_text is non-NULL and any records have been |
a699449b | 2016 | * dropped, a dropped message will be written out first. |
1da177e4 | 2017 | */ |
03a749e6 JO |
2018 | static void call_console_driver(struct console *con, const char *text, size_t len, |
2019 | char *dropped_text) | |
1da177e4 | 2020 | { |
a699449b | 2021 | size_t dropped_len; |
1da177e4 | 2022 | |
03a749e6 JO |
2023 | if (con->dropped && dropped_text) { |
2024 | dropped_len = snprintf(dropped_text, DROPPED_TEXT_MAX, | |
896fbe20 | 2025 | "** %lu printk messages dropped **\n", |
a699449b JO |
2026 | con->dropped); |
2027 | con->dropped = 0; | |
2028 | con->write(con, dropped_text, dropped_len); | |
896fbe20 JO |
2029 | } |
2030 | ||
a699449b | 2031 | con->write(con, text, len); |
1da177e4 LT |
2032 | } |
2033 | ||
002eb6ad JO |
2034 | /* |
2035 | * Recursion is tracked separately on each CPU. If NMIs are supported, an | |
2036 | * additional NMI context per CPU is also separately tracked. Until per-CPU | |
2037 | * is available, a separate "early tracking" is performed. | |
2038 | */ | |
2039 | static DEFINE_PER_CPU(u8, printk_count); | |
2040 | static u8 printk_count_early; | |
2041 | #ifdef CONFIG_HAVE_NMI | |
2042 | static DEFINE_PER_CPU(u8, printk_count_nmi); | |
2043 | static u8 printk_count_nmi_early; | |
2044 | #endif | |
2045 | ||
2046 | /* | |
2047 | * Recursion is limited to keep the output sane. printk() should not require | |
2048 | * more than 1 level of recursion (allowing, for example, printk() to trigger | |
2049 | * a WARN), but a higher value is used in case some printk-internal errors | |
2050 | * exist, such as the ringbuffer validation checks failing. | |
2051 | */ | |
2052 | #define PRINTK_MAX_RECURSION 3 | |
2053 | ||
2054 | /* | |
2055 | * Return a pointer to the dedicated counter for the CPU+context of the | |
2056 | * caller. | |
2057 | */ | |
2058 | static u8 *__printk_recursion_counter(void) | |
2059 | { | |
2060 | #ifdef CONFIG_HAVE_NMI | |
2061 | if (in_nmi()) { | |
2062 | if (printk_percpu_data_ready()) | |
2063 | return this_cpu_ptr(&printk_count_nmi); | |
2064 | return &printk_count_nmi_early; | |
2065 | } | |
2066 | #endif | |
2067 | if (printk_percpu_data_ready()) | |
2068 | return this_cpu_ptr(&printk_count); | |
2069 | return &printk_count_early; | |
2070 | } | |
2071 | ||
2072 | /* | |
2073 | * Enter recursion tracking. Interrupts are disabled to simplify tracking. | |
2074 | * The caller must check the boolean return value to see if the recursion is | |
2075 | * allowed. On failure, interrupts are not disabled. | |
2076 | * | |
2077 | * @recursion_ptr must be a variable of type (u8 *) and is the same variable | |
2078 | * that is passed to printk_exit_irqrestore(). | |
2079 | */ | |
2080 | #define printk_enter_irqsave(recursion_ptr, flags) \ | |
2081 | ({ \ | |
2082 | bool success = true; \ | |
2083 | \ | |
2084 | typecheck(u8 *, recursion_ptr); \ | |
2085 | local_irq_save(flags); \ | |
2086 | (recursion_ptr) = __printk_recursion_counter(); \ | |
2087 | if (*(recursion_ptr) > PRINTK_MAX_RECURSION) { \ | |
2088 | local_irq_restore(flags); \ | |
2089 | success = false; \ | |
2090 | } else { \ | |
2091 | (*(recursion_ptr))++; \ | |
2092 | } \ | |
2093 | success; \ | |
2094 | }) | |
2095 | ||
2096 | /* Exit recursion tracking, restoring interrupts. */ | |
2097 | #define printk_exit_irqrestore(recursion_ptr, flags) \ | |
2098 | do { \ | |
2099 | typecheck(u8 *, recursion_ptr); \ | |
2100 | (*(recursion_ptr))--; \ | |
2101 | local_irq_restore(flags); \ | |
2102 | } while (0) | |
2103 | ||
af91322e DY |
2104 | int printk_delay_msec __read_mostly; |
2105 | ||
1f47e8af | 2106 | static inline void printk_delay(int level) |
af91322e | 2107 | { |
1f47e8af JO |
2108 | boot_delay_msec(level); |
2109 | ||
af91322e DY |
2110 | if (unlikely(printk_delay_msec)) { |
2111 | int m = printk_delay_msec; | |
2112 | ||
2113 | while (m--) { | |
2114 | mdelay(1); | |
2115 | touch_nmi_watchdog(); | |
2116 | } | |
2117 | } | |
2118 | } | |
2119 | ||
cbae05d3 TH |
2120 | static inline u32 printk_caller_id(void) |
2121 | { | |
2122 | return in_task() ? task_pid_nr(current) : | |
9f0844de | 2123 | 0x80000000 + smp_processor_id(); |
cbae05d3 TH |
2124 | } |
2125 | ||
b031a684 | 2126 | /** |
f3d75cf5 | 2127 | * printk_parse_prefix - Parse level and control flags. |
b031a684 JO |
2128 | * |
2129 | * @text: The terminated text message. | |
2130 | * @level: A pointer to the current level value, will be updated. | |
a1ad4b8a | 2131 | * @flags: A pointer to the current printk_info flags, will be updated. |
b031a684 JO |
2132 | * |
2133 | * @level may be NULL if the caller is not interested in the parsed value. | |
2134 | * Otherwise the variable pointed to by @level must be set to | |
2135 | * LOGLEVEL_DEFAULT in order to be updated with the parsed value. | |
2136 | * | |
a1ad4b8a CD |
2137 | * @flags may be NULL if the caller is not interested in the parsed value. |
2138 | * Otherwise the variable pointed to by @flags will be OR'd with the parsed | |
b031a684 JO |
2139 | * value. |
2140 | * | |
2141 | * Return: The length of the parsed level and control flags. | |
2142 | */ | |
f3d75cf5 | 2143 | u16 printk_parse_prefix(const char *text, int *level, |
a1ad4b8a | 2144 | enum printk_info_flags *flags) |
c362c7ff | 2145 | { |
b031a684 JO |
2146 | u16 prefix_len = 0; |
2147 | int kern_level; | |
cbae05d3 | 2148 | |
b031a684 JO |
2149 | while (*text) { |
2150 | kern_level = printk_get_level(text); | |
2151 | if (!kern_level) | |
2152 | break; | |
f5f022e5 | 2153 | |
b031a684 JO |
2154 | switch (kern_level) { |
2155 | case '0' ... '7': | |
2156 | if (level && *level == LOGLEVEL_DEFAULT) | |
2157 | *level = kern_level - '0'; | |
2158 | break; | |
2159 | case 'c': /* KERN_CONT */ | |
a1ad4b8a CD |
2160 | if (flags) |
2161 | *flags |= LOG_CONT; | |
b031a684 JO |
2162 | } |
2163 | ||
2164 | prefix_len += 2; | |
2165 | text += 2; | |
2166 | } | |
2167 | ||
2168 | return prefix_len; | |
2169 | } | |
2170 | ||
264a7504 | 2171 | __printf(5, 0) |
a1ad4b8a CD |
2172 | static u16 printk_sprint(char *text, u16 size, int facility, |
2173 | enum printk_info_flags *flags, const char *fmt, | |
2174 | va_list args) | |
b031a684 JO |
2175 | { |
2176 | u16 text_len; | |
2177 | ||
2178 | text_len = vscnprintf(text, size, fmt, args); | |
2179 | ||
2180 | /* Mark and strip a trailing newline. */ | |
2181 | if (text_len && text[text_len - 1] == '\n') { | |
2182 | text_len--; | |
a1ad4b8a | 2183 | *flags |= LOG_NEWLINE; |
b031a684 JO |
2184 | } |
2185 | ||
2186 | /* Strip log level and control flags. */ | |
2187 | if (facility == 0) { | |
2188 | u16 prefix_len; | |
2189 | ||
f3d75cf5 | 2190 | prefix_len = printk_parse_prefix(text, NULL, NULL); |
b031a684 JO |
2191 | if (prefix_len) { |
2192 | text_len -= prefix_len; | |
2193 | memmove(text, text + prefix_len, text_len); | |
f5f022e5 | 2194 | } |
c362c7ff LT |
2195 | } |
2196 | ||
701850dc ME |
2197 | trace_console_rcuidle(text, text_len); |
2198 | ||
b031a684 | 2199 | return text_len; |
c362c7ff LT |
2200 | } |
2201 | ||
b031a684 | 2202 | __printf(4, 0) |
ba552399 | 2203 | int vprintk_store(int facility, int level, |
74caba7f | 2204 | const struct dev_printk_info *dev_info, |
ba552399 | 2205 | const char *fmt, va_list args) |
1da177e4 | 2206 | { |
6b916706 | 2207 | struct prb_reserved_entry e; |
a1ad4b8a | 2208 | enum printk_info_flags flags = 0; |
6b916706 | 2209 | struct printk_record r; |
002eb6ad | 2210 | unsigned long irqflags; |
6b916706 | 2211 | u16 trunc_msg_len = 0; |
b031a684 | 2212 | char prefix_buf[8]; |
002eb6ad | 2213 | u8 *recursion_ptr; |
b031a684 JO |
2214 | u16 reserve_size; |
2215 | va_list args2; | |
9f0844de | 2216 | u32 caller_id; |
6b916706 | 2217 | u16 text_len; |
002eb6ad | 2218 | int ret = 0; |
6b916706 | 2219 | u64 ts_nsec; |
bfe8df3d | 2220 | |
9f0844de JO |
2221 | if (!printk_enter_irqsave(recursion_ptr, irqflags)) |
2222 | return 0; | |
2223 | ||
7ff9554b | 2224 | /* |
6b916706 JO |
2225 | * Since the duration of printk() can vary depending on the message |
2226 | * and state of the ringbuffer, grab the timestamp now so that it is | |
2227 | * close to the call of printk(). This provides a more deterministic | |
2228 | * timestamp with respect to the caller. | |
7ff9554b | 2229 | */ |
6b916706 | 2230 | ts_nsec = local_clock(); |
5fd29d6c | 2231 | |
9f0844de | 2232 | caller_id = printk_caller_id(); |
002eb6ad | 2233 | |
7ff9554b | 2234 | /* |
b031a684 JO |
2235 | * The sprintf needs to come first since the syslog prefix might be |
2236 | * passed in as a parameter. An extra byte must be reserved so that | |
2237 | * later the vscnprintf() into the reserved buffer has room for the | |
2238 | * terminating '\0', which is not counted by vsnprintf(). | |
7ff9554b | 2239 | */ |
b031a684 JO |
2240 | va_copy(args2, args); |
2241 | reserve_size = vsnprintf(&prefix_buf[0], sizeof(prefix_buf), fmt, args2) + 1; | |
2242 | va_end(args2); | |
9d90c8d9 | 2243 | |
b031a684 JO |
2244 | if (reserve_size > LOG_LINE_MAX) |
2245 | reserve_size = LOG_LINE_MAX; | |
088a52aa | 2246 | |
b031a684 JO |
2247 | /* Extract log level or control flags. */ |
2248 | if (facility == 0) | |
f3d75cf5 | 2249 | printk_parse_prefix(&prefix_buf[0], &level, &flags); |
5fd29d6c | 2250 | |
a39d4a85 | 2251 | if (level == LOGLEVEL_DEFAULT) |
c313af14 | 2252 | level = default_message_loglevel; |
9d90c8d9 | 2253 | |
74caba7f | 2254 | if (dev_info) |
a1ad4b8a | 2255 | flags |= LOG_NEWLINE; |
9d90c8d9 | 2256 | |
a1ad4b8a | 2257 | if (flags & LOG_CONT) { |
b031a684 | 2258 | prb_rec_init_wr(&r, reserve_size); |
6b916706 | 2259 | if (prb_reserve_in_last(&e, prb, &r, caller_id, LOG_LINE_MAX)) { |
b031a684 | 2260 | text_len = printk_sprint(&r.text_buf[r.info->text_len], reserve_size, |
a1ad4b8a | 2261 | facility, &flags, fmt, args); |
6b916706 | 2262 | r.info->text_len += text_len; |
088a52aa | 2263 | |
a1ad4b8a | 2264 | if (flags & LOG_NEWLINE) { |
6b916706 JO |
2265 | r.info->flags |= LOG_NEWLINE; |
2266 | prb_final_commit(&e); | |
2267 | } else { | |
2268 | prb_commit(&e); | |
088a52aa | 2269 | } |
4bcc595c | 2270 | |
002eb6ad JO |
2271 | ret = text_len; |
2272 | goto out; | |
5fd29d6c LT |
2273 | } |
2274 | } | |
2275 | ||
6b916706 JO |
2276 | /* |
2277 | * Explicitly initialize the record before every prb_reserve() call. | |
2278 | * prb_reserve_in_last() and prb_reserve() purposely invalidate the | |
2279 | * structure when they fail. | |
2280 | */ | |
b031a684 | 2281 | prb_rec_init_wr(&r, reserve_size); |
6b916706 JO |
2282 | if (!prb_reserve(&e, prb, &r)) { |
2283 | /* truncate the message if it is too long for empty buffer */ | |
b031a684 | 2284 | truncate_msg(&reserve_size, &trunc_msg_len); |
9d90c8d9 | 2285 | |
b031a684 | 2286 | prb_rec_init_wr(&r, reserve_size + trunc_msg_len); |
6b916706 | 2287 | if (!prb_reserve(&e, prb, &r)) |
002eb6ad | 2288 | goto out; |
6b916706 JO |
2289 | } |
2290 | ||
2291 | /* fill message */ | |
a1ad4b8a | 2292 | text_len = printk_sprint(&r.text_buf[0], reserve_size, facility, &flags, fmt, args); |
6b916706 JO |
2293 | if (trunc_msg_len) |
2294 | memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len); | |
2295 | r.info->text_len = text_len + trunc_msg_len; | |
2296 | r.info->facility = facility; | |
2297 | r.info->level = level & 7; | |
a1ad4b8a | 2298 | r.info->flags = flags & 0x1f; |
6b916706 JO |
2299 | r.info->ts_nsec = ts_nsec; |
2300 | r.info->caller_id = caller_id; | |
74caba7f | 2301 | if (dev_info) |
6b916706 | 2302 | memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info)); |
ac60ad74 | 2303 | |
6b916706 | 2304 | /* A message without a trailing newline can be continued. */ |
a1ad4b8a | 2305 | if (!(flags & LOG_NEWLINE)) |
6b916706 JO |
2306 | prb_commit(&e); |
2307 | else | |
2308 | prb_final_commit(&e); | |
2309 | ||
002eb6ad JO |
2310 | ret = text_len + trunc_msg_len; |
2311 | out: | |
2312 | printk_exit_irqrestore(recursion_ptr, irqflags); | |
2313 | return ret; | |
ba552399 | 2314 | } |
1da177e4 | 2315 | |
ba552399 | 2316 | asmlinkage int vprintk_emit(int facility, int level, |
74caba7f | 2317 | const struct dev_printk_info *dev_info, |
ba552399 PM |
2318 | const char *fmt, va_list args) |
2319 | { | |
2320 | int printed_len; | |
8749efc0 | 2321 | bool in_sched = false; |
ba552399 | 2322 | |
c39ea0b9 FT |
2323 | /* Suppress unimportant messages after panic happens */ |
2324 | if (unlikely(suppress_printk)) | |
2325 | return 0; | |
2326 | ||
13fb0f74 SB |
2327 | if (unlikely(suppress_panic_printk) && |
2328 | atomic_read(&panic_cpu) != raw_smp_processor_id()) | |
2329 | return 0; | |
2330 | ||
ba552399 PM |
2331 | if (level == LOGLEVEL_SCHED) { |
2332 | level = LOGLEVEL_DEFAULT; | |
2333 | in_sched = true; | |
2334 | } | |
2335 | ||
1f47e8af | 2336 | printk_delay(level); |
ba552399 | 2337 | |
74caba7f | 2338 | printed_len = vprintk_store(facility, level, dev_info, fmt, args); |
939f04be | 2339 | |
458df9fd | 2340 | /* If called from the scheduler, we can not call up(). */ |
5831788a | 2341 | if (!in_sched) { |
fd5f7cde | 2342 | /* |
a699449b | 2343 | * The caller may be holding system-critical or |
5831788a | 2344 | * timing-sensitive locks. Disable preemption during |
a699449b JO |
2345 | * printing of all remaining records to all consoles so that |
2346 | * this context can return as soon as possible. Hopefully | |
2347 | * another printk() caller will take over the printing. | |
fd5f7cde SS |
2348 | */ |
2349 | preempt_disable(); | |
d18bbc21 AM |
2350 | /* |
2351 | * Try to acquire and then immediately release the console | |
a699449b JO |
2352 | * semaphore. The release will print out buffers. With the |
2353 | * spinning variant, this context tries to take over the | |
2354 | * printing from another printing context. | |
d18bbc21 | 2355 | */ |
c162d5b4 | 2356 | if (console_trylock_spinning()) |
d18bbc21 | 2357 | console_unlock(); |
fd5f7cde | 2358 | preempt_enable(); |
d18bbc21 | 2359 | } |
76a8ad29 | 2360 | |
8749efc0 | 2361 | wake_up_klogd(); |
1da177e4 LT |
2362 | return printed_len; |
2363 | } | |
7ff9554b KS |
2364 | EXPORT_SYMBOL(vprintk_emit); |
2365 | ||
a0cba217 | 2366 | int vprintk_default(const char *fmt, va_list args) |
afdc34a3 | 2367 | { |
74caba7f | 2368 | return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, fmt, args); |
afdc34a3 SRRH |
2369 | } |
2370 | EXPORT_SYMBOL_GPL(vprintk_default); | |
2371 | ||
33701557 | 2372 | asmlinkage __visible int _printk(const char *fmt, ...) |
7ff9554b KS |
2373 | { |
2374 | va_list args; | |
2375 | int r; | |
2376 | ||
7ff9554b | 2377 | va_start(args, fmt); |
28e1745b | 2378 | r = vprintk(fmt, args); |
7ff9554b KS |
2379 | va_end(args); |
2380 | ||
2381 | return r; | |
2382 | } | |
33701557 | 2383 | EXPORT_SYMBOL(_printk); |
7f3a781d | 2384 | |
c60ba2d3 | 2385 | static bool pr_flush(int timeout_ms, bool reset_on_progress); |
3b604ca8 JO |
2386 | static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress); |
2387 | ||
96efedf1 | 2388 | #else /* CONFIG_PRINTK */ |
d59745ce | 2389 | |
cf5b0208 | 2390 | #define CONSOLE_LOG_MAX 0 |
03a749e6 | 2391 | #define DROPPED_TEXT_MAX 0 |
e80c1a9d | 2392 | #define printk_time false |
249771b8 | 2393 | |
896fbe20 JO |
2394 | #define prb_read_valid(rb, seq, r) false |
2395 | #define prb_first_valid_seq(rb) 0 | |
a699449b | 2396 | #define prb_next_seq(rb) 0 |
896fbe20 | 2397 | |
96efedf1 | 2398 | static u64 syslog_seq; |
896fbe20 JO |
2399 | |
2400 | static size_t record_print_text(const struct printk_record *r, | |
2401 | bool syslog, bool time) | |
2402 | { | |
2403 | return 0; | |
2404 | } | |
2405 | static ssize_t info_print_ext_header(char *buf, size_t size, | |
2406 | struct printk_info *info) | |
2407 | { | |
2408 | return 0; | |
2409 | } | |
6fe29354 | 2410 | static ssize_t msg_print_ext_body(char *buf, size_t size, |
74caba7f JO |
2411 | char *text, size_t text_len, |
2412 | struct dev_printk_info *dev_info) { return 0; } | |
c162d5b4 | 2413 | static void console_lock_spinning_enable(void) { } |
fc956ae0 | 2414 | static int console_lock_spinning_disable_and_check(int cookie) { return 0; } |
03a749e6 JO |
2415 | static void call_console_driver(struct console *con, const char *text, size_t len, |
2416 | char *dropped_text) | |
2417 | { | |
2418 | } | |
a6ae928c | 2419 | static bool suppress_message_printing(int level) { return false; } |
c60ba2d3 | 2420 | static bool pr_flush(int timeout_ms, bool reset_on_progress) { return true; } |
3b604ca8 | 2421 | static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) { return true; } |
d59745ce | 2422 | |
7f3a781d | 2423 | #endif /* CONFIG_PRINTK */ |
d59745ce | 2424 | |
d0380e6c TG |
2425 | #ifdef CONFIG_EARLY_PRINTK |
2426 | struct console *early_console; | |
2427 | ||
722a9f92 | 2428 | asmlinkage __visible void early_printk(const char *fmt, ...) |
d0380e6c TG |
2429 | { |
2430 | va_list ap; | |
1dc6244b JP |
2431 | char buf[512]; |
2432 | int n; | |
2433 | ||
2434 | if (!early_console) | |
2435 | return; | |
d0380e6c TG |
2436 | |
2437 | va_start(ap, fmt); | |
1dc6244b | 2438 | n = vscnprintf(buf, sizeof(buf), fmt, ap); |
d0380e6c | 2439 | va_end(ap); |
1dc6244b JP |
2440 | |
2441 | early_console->write(early_console, buf, n); | |
d0380e6c TG |
2442 | } |
2443 | #endif | |
2444 | ||
a5a763b2 AK |
2445 | static void set_user_specified(struct console_cmdline *c, bool user_specified) |
2446 | { | |
2447 | if (!user_specified) | |
2448 | return; | |
2449 | ||
2450 | /* | |
2451 | * @c console was defined by the user on the command line. | |
2452 | * Do not clear when added twice also by SPCR or the device tree. | |
2453 | */ | |
2454 | c->user_specified = true; | |
2455 | /* At least one console defined by the user on the command line. */ | |
2456 | console_set_on_cmdline = 1; | |
2457 | } | |
2458 | ||
f7511d5f | 2459 | static int __add_preferred_console(char *name, int idx, char *options, |
e369d822 | 2460 | char *brl_options, bool user_specified) |
f7511d5f ST |
2461 | { |
2462 | struct console_cmdline *c; | |
2463 | int i; | |
2464 | ||
2465 | /* | |
2466 | * See if this tty is not yet registered, and | |
2467 | * if we have a slot free. | |
2468 | */ | |
dac8bbba PM |
2469 | for (i = 0, c = console_cmdline; |
2470 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2471 | i++, c++) { | |
23475408 | 2472 | if (strcmp(c->name, name) == 0 && c->index == idx) { |
dac8bbba PM |
2473 | if (!brl_options) |
2474 | preferred_console = i; | |
a5a763b2 | 2475 | set_user_specified(c, user_specified); |
23475408 | 2476 | return 0; |
f7511d5f | 2477 | } |
23475408 | 2478 | } |
f7511d5f ST |
2479 | if (i == MAX_CMDLINECONSOLES) |
2480 | return -E2BIG; | |
2481 | if (!brl_options) | |
ad86ee2b | 2482 | preferred_console = i; |
7365df19 | 2483 | strscpy(c->name, name, sizeof(c->name)); |
f7511d5f | 2484 | c->options = options; |
a5a763b2 | 2485 | set_user_specified(c, user_specified); |
bbeddf52 JP |
2486 | braille_set_options(c, brl_options); |
2487 | ||
f7511d5f ST |
2488 | c->index = idx; |
2489 | return 0; | |
2490 | } | |
cca10d58 SS |
2491 | |
2492 | static int __init console_msg_format_setup(char *str) | |
2493 | { | |
2494 | if (!strcmp(str, "syslog")) | |
2495 | console_msg_format = MSG_FORMAT_SYSLOG; | |
2496 | if (!strcmp(str, "default")) | |
2497 | console_msg_format = MSG_FORMAT_DEFAULT; | |
2498 | return 1; | |
2499 | } | |
2500 | __setup("console_msg_format=", console_msg_format_setup); | |
2501 | ||
2ea1c539 | 2502 | /* |
0b90fec3 AE |
2503 | * Set up a console. Called via do_early_param() in init/main.c |
2504 | * for each "console=" parameter in the boot command line. | |
2ea1c539 JB |
2505 | */ |
2506 | static int __init console_setup(char *str) | |
2507 | { | |
0b90fec3 | 2508 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ |
f7511d5f | 2509 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
2510 | int idx; |
2511 | ||
3cffa06a PM |
2512 | /* |
2513 | * console="" or console=null have been suggested as a way to | |
2514 | * disable console output. Use ttynull that has been created | |
acebb559 | 2515 | * for exactly this purpose. |
3cffa06a PM |
2516 | */ |
2517 | if (str[0] == 0 || strcmp(str, "null") == 0) { | |
2518 | __add_preferred_console("ttynull", 0, NULL, NULL, true); | |
48021f98 | 2519 | return 1; |
3cffa06a | 2520 | } |
48021f98 | 2521 | |
bbeddf52 JP |
2522 | if (_braille_console_setup(&str, &brl_options)) |
2523 | return 1; | |
f7511d5f | 2524 | |
2ea1c539 JB |
2525 | /* |
2526 | * Decode str into name, index, options. | |
2527 | */ | |
2528 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
2529 | strcpy(buf, "ttyS"); |
2530 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 2531 | } else { |
eaa944af | 2532 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 2533 | } |
eaa944af | 2534 | buf[sizeof(buf) - 1] = 0; |
249771b8 AE |
2535 | options = strchr(str, ','); |
2536 | if (options) | |
2ea1c539 JB |
2537 | *(options++) = 0; |
2538 | #ifdef __sparc__ | |
2539 | if (!strcmp(str, "ttya")) | |
eaa944af | 2540 | strcpy(buf, "ttyS0"); |
2ea1c539 | 2541 | if (!strcmp(str, "ttyb")) |
eaa944af | 2542 | strcpy(buf, "ttyS1"); |
2ea1c539 | 2543 | #endif |
eaa944af | 2544 | for (s = buf; *s; s++) |
249771b8 | 2545 | if (isdigit(*s) || *s == ',') |
2ea1c539 JB |
2546 | break; |
2547 | idx = simple_strtoul(s, NULL, 10); | |
2548 | *s = 0; | |
2549 | ||
e369d822 | 2550 | __add_preferred_console(buf, idx, options, brl_options, true); |
2ea1c539 JB |
2551 | return 1; |
2552 | } | |
2553 | __setup("console=", console_setup); | |
2554 | ||
3c0547ba MM |
2555 | /** |
2556 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
2557 | * @name: device name |
2558 | * @idx: device index | |
2559 | * @options: options for this console | |
3c0547ba MM |
2560 | * |
2561 | * The last preferred console added will be used for kernel messages | |
2562 | * and stdin/out/err for init. Normally this is used by console_setup | |
2563 | * above to handle user-supplied console arguments; however it can also | |
2564 | * be used by arch-specific code either to override the user or more | |
2565 | * commonly to provide a default console (ie from PROM variables) when | |
2566 | * the user has not supplied one. | |
2567 | */ | |
fb445ee5 | 2568 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 2569 | { |
e369d822 | 2570 | return __add_preferred_console(name, idx, options, NULL, false); |
3c0547ba MM |
2571 | } |
2572 | ||
d25d9fec | 2573 | bool console_suspend_enabled = true; |
8f4ce8c3 AS |
2574 | EXPORT_SYMBOL(console_suspend_enabled); |
2575 | ||
2576 | static int __init console_suspend_disable(char *str) | |
2577 | { | |
d25d9fec | 2578 | console_suspend_enabled = false; |
8f4ce8c3 AS |
2579 | return 1; |
2580 | } | |
2581 | __setup("no_console_suspend", console_suspend_disable); | |
134620f7 YZ |
2582 | module_param_named(console_suspend, console_suspend_enabled, |
2583 | bool, S_IRUGO | S_IWUSR); | |
2584 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" | |
2585 | " and hibernate operations"); | |
8f4ce8c3 | 2586 | |
10102a89 DS |
2587 | static bool printk_console_no_auto_verbose; |
2588 | ||
2589 | void console_verbose(void) | |
2590 | { | |
2591 | if (console_loglevel && !printk_console_no_auto_verbose) | |
2592 | console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; | |
2593 | } | |
2594 | EXPORT_SYMBOL_GPL(console_verbose); | |
2595 | ||
2596 | module_param_named(console_no_auto_verbose, printk_console_no_auto_verbose, bool, 0644); | |
2597 | MODULE_PARM_DESC(console_no_auto_verbose, "Disable console loglevel raise to highest on oops/panic/etc"); | |
2598 | ||
557240b4 LT |
2599 | /** |
2600 | * suspend_console - suspend the console subsystem | |
2601 | * | |
2602 | * This disables printk() while we go into suspend states | |
2603 | */ | |
2604 | void suspend_console(void) | |
2605 | { | |
8f4ce8c3 AS |
2606 | if (!console_suspend_enabled) |
2607 | return; | |
47319f71 | 2608 | pr_info("Suspending console(s) (use no_console_suspend to debug)\n"); |
3b604ca8 | 2609 | pr_flush(1000, true); |
ac751efa | 2610 | console_lock(); |
557240b4 | 2611 | console_suspended = 1; |
bd8d7cf5 | 2612 | up_console_sem(); |
557240b4 LT |
2613 | } |
2614 | ||
2615 | void resume_console(void) | |
2616 | { | |
8f4ce8c3 AS |
2617 | if (!console_suspend_enabled) |
2618 | return; | |
bd8d7cf5 | 2619 | down_console_sem(); |
557240b4 | 2620 | console_suspended = 0; |
ac751efa | 2621 | console_unlock(); |
3b604ca8 | 2622 | pr_flush(1000, true); |
557240b4 LT |
2623 | } |
2624 | ||
034260d6 KC |
2625 | /** |
2626 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
90b14889 | 2627 | * @cpu: unused |
034260d6 KC |
2628 | * |
2629 | * If printk() is called from a CPU that is not online yet, the messages | |
64ca752d SS |
2630 | * will be printed on the console only if there are CON_ANYTIME consoles. |
2631 | * This function is called when a new CPU comes online (or fails to come | |
2632 | * up) or goes offline. | |
034260d6 | 2633 | */ |
90b14889 SAS |
2634 | static int console_cpu_notify(unsigned int cpu) |
2635 | { | |
f97960fb | 2636 | if (!cpuhp_tasks_frozen) { |
64ca752d SS |
2637 | /* If trylock fails, someone else is doing the printing */ |
2638 | if (console_trylock()) | |
2639 | console_unlock(); | |
034260d6 | 2640 | } |
90b14889 | 2641 | return 0; |
034260d6 KC |
2642 | } |
2643 | ||
1da177e4 | 2644 | /** |
848a9c10 | 2645 | * console_lock - block the console subsystem from printing |
1da177e4 | 2646 | * |
848a9c10 JO |
2647 | * Acquires a lock which guarantees that no consoles will |
2648 | * be in or enter their write() callback. | |
1da177e4 LT |
2649 | * |
2650 | * Can sleep, returns nothing. | |
2651 | */ | |
ac751efa | 2652 | void console_lock(void) |
1da177e4 | 2653 | { |
6b898c07 DV |
2654 | might_sleep(); |
2655 | ||
bd8d7cf5 | 2656 | down_console_sem(); |
403f3075 AH |
2657 | if (console_suspended) |
2658 | return; | |
007eeab7 | 2659 | console_locked = 1; |
1da177e4 LT |
2660 | console_may_schedule = 1; |
2661 | } | |
ac751efa | 2662 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 2663 | |
ac751efa | 2664 | /** |
848a9c10 | 2665 | * console_trylock - try to block the console subsystem from printing |
ac751efa | 2666 | * |
848a9c10 JO |
2667 | * Try to acquire a lock which guarantees that no consoles will |
2668 | * be in or enter their write() callback. | |
ac751efa TH |
2669 | * |
2670 | * returns 1 on success, and 0 on failure to acquire the lock. | |
2671 | */ | |
2672 | int console_trylock(void) | |
1da177e4 | 2673 | { |
bd8d7cf5 | 2674 | if (down_trylock_console_sem()) |
ac751efa | 2675 | return 0; |
403f3075 | 2676 | if (console_suspended) { |
bd8d7cf5 | 2677 | up_console_sem(); |
ac751efa | 2678 | return 0; |
403f3075 | 2679 | } |
007eeab7 | 2680 | console_locked = 1; |
fd5f7cde | 2681 | console_may_schedule = 0; |
ac751efa | 2682 | return 1; |
1da177e4 | 2683 | } |
ac751efa | 2684 | EXPORT_SYMBOL(console_trylock); |
1da177e4 LT |
2685 | |
2686 | int is_console_locked(void) | |
2687 | { | |
2d9ef940 | 2688 | return console_locked; |
1da177e4 | 2689 | } |
d48de54a | 2690 | EXPORT_SYMBOL(is_console_locked); |
1da177e4 | 2691 | |
8ebc476f SB |
2692 | /* |
2693 | * Return true when this CPU should unlock console_sem without pushing all | |
2694 | * messages to the console. This reduces the chance that the console is | |
2695 | * locked when the panic CPU tries to use it. | |
2696 | */ | |
2697 | static bool abandon_console_lock_in_panic(void) | |
2698 | { | |
2699 | if (!panic_in_progress()) | |
2700 | return false; | |
2701 | ||
2702 | /* | |
2703 | * We can use raw_smp_processor_id() here because it is impossible for | |
2704 | * the task to be migrated to the panic_cpu, or away from it. If | |
2705 | * panic_cpu has already been set, and we're not currently executing on | |
2706 | * that CPU, then we never will be. | |
2707 | */ | |
2708 | return atomic_read(&panic_cpu) != raw_smp_processor_id(); | |
2709 | } | |
2710 | ||
5831788a PM |
2711 | /* |
2712 | * Check if the given console is currently capable and allowed to print | |
2713 | * records. | |
2714 | * | |
12f1da5f | 2715 | * Requires the console_srcu_read_lock. |
5831788a PM |
2716 | */ |
2717 | static inline bool console_is_usable(struct console *con) | |
a699449b | 2718 | { |
12f1da5f JO |
2719 | short flags = console_srcu_read_flags(con); |
2720 | ||
2721 | if (!(flags & CON_ENABLED)) | |
5831788a PM |
2722 | return false; |
2723 | ||
2724 | if (!con->write) | |
a699449b JO |
2725 | return false; |
2726 | ||
2727 | /* | |
2728 | * Console drivers may assume that per-cpu resources have been | |
2729 | * allocated. So unless they're explicitly marked as being able to | |
2730 | * cope (CON_ANYTIME) don't call them until this CPU is officially up. | |
2731 | */ | |
12f1da5f | 2732 | if (!cpu_online(raw_smp_processor_id()) && !(flags & CON_ANYTIME)) |
a699449b JO |
2733 | return false; |
2734 | ||
2735 | return true; | |
2736 | } | |
2737 | ||
2738 | static void __console_unlock(void) | |
2739 | { | |
007eeab7 | 2740 | console_locked = 0; |
a699449b JO |
2741 | up_console_sem(); |
2742 | } | |
2743 | ||
2744 | /* | |
2745 | * Print one record for the given console. The record printed is whatever | |
2746 | * record is the next available record for the given console. | |
2747 | * | |
03a749e6 JO |
2748 | * @text is a buffer of size CONSOLE_LOG_MAX. |
2749 | * | |
2750 | * If extended messages should be printed, @ext_text is a buffer of size | |
2751 | * CONSOLE_EXT_LOG_MAX. Otherwise @ext_text must be NULL. | |
2752 | * | |
2753 | * If dropped messages should be printed, @dropped_text is a buffer of size | |
2754 | * DROPPED_TEXT_MAX. Otherwise @dropped_text must be NULL. | |
2755 | * | |
a699449b | 2756 | * @handover will be set to true if a printk waiter has taken over the |
fc956ae0 JO |
2757 | * console_lock, in which case the caller is no longer holding both the |
2758 | * console_lock and the SRCU read lock. Otherwise it is set to false. | |
2759 | * | |
2760 | * @cookie is the cookie from the SRCU read lock. | |
a699449b JO |
2761 | * |
2762 | * Returns false if the given console has no next record to print, otherwise | |
2763 | * true. | |
a8199371 | 2764 | * |
fc956ae0 | 2765 | * Requires the console_lock and the SRCU read lock. |
a8199371 | 2766 | */ |
2d9ef940 | 2767 | static bool console_emit_next_record(struct console *con, char *text, char *ext_text, |
fc956ae0 | 2768 | char *dropped_text, bool *handover, int cookie) |
a8199371 | 2769 | { |
2d9ef940 | 2770 | static int panic_console_dropped; |
a699449b JO |
2771 | struct printk_info info; |
2772 | struct printk_record r; | |
2773 | unsigned long flags; | |
2774 | char *write_text; | |
2775 | size_t len; | |
2776 | ||
03a749e6 | 2777 | prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX); |
a699449b | 2778 | |
2d9ef940 | 2779 | *handover = false; |
a699449b JO |
2780 | |
2781 | if (!prb_read_valid(prb, con->seq, &r)) | |
2782 | return false; | |
2783 | ||
2784 | if (con->seq != r.info->seq) { | |
2785 | con->dropped += r.info->seq - con->seq; | |
2786 | con->seq = r.info->seq; | |
2d9ef940 | 2787 | if (panic_in_progress() && panic_console_dropped++ > 10) { |
a699449b JO |
2788 | suppress_panic_printk = 1; |
2789 | pr_warn_once("Too many dropped messages. Suppress messages on non-panic CPUs to prevent livelock.\n"); | |
2790 | } | |
2791 | } | |
2792 | ||
2793 | /* Skip record that has level above the console loglevel. */ | |
2794 | if (suppress_message_printing(r.info->level)) { | |
2795 | con->seq++; | |
2796 | goto skip; | |
2797 | } | |
2798 | ||
03a749e6 JO |
2799 | if (ext_text) { |
2800 | write_text = ext_text; | |
2801 | len = info_print_ext_header(ext_text, CONSOLE_EXT_LOG_MAX, r.info); | |
2802 | len += msg_print_ext_body(ext_text + len, CONSOLE_EXT_LOG_MAX - len, | |
a699449b JO |
2803 | &r.text_buf[0], r.info->text_len, &r.info->dev_info); |
2804 | } else { | |
03a749e6 | 2805 | write_text = text; |
a699449b JO |
2806 | len = record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, printk_time); |
2807 | } | |
2808 | ||
2d9ef940 PM |
2809 | /* |
2810 | * While actively printing out messages, if another printk() | |
2811 | * were to occur on another CPU, it may wait for this one to | |
2812 | * finish. This task can not be preempted if there is a | |
2813 | * waiter waiting to take over. | |
2814 | * | |
2815 | * Interrupts are disabled because the hand over to a waiter | |
2816 | * must not be interrupted until the hand over is completed | |
2817 | * (@console_waiter is cleared). | |
2818 | */ | |
2819 | printk_safe_enter_irqsave(flags); | |
2820 | console_lock_spinning_enable(); | |
a699449b | 2821 | |
2d9ef940 | 2822 | stop_critical_timings(); /* don't trace print latency */ |
03a749e6 | 2823 | call_console_driver(con, write_text, len, dropped_text); |
2d9ef940 | 2824 | start_critical_timings(); |
a699449b JO |
2825 | |
2826 | con->seq++; | |
2827 | ||
fc956ae0 | 2828 | *handover = console_lock_spinning_disable_and_check(cookie); |
2d9ef940 | 2829 | printk_safe_exit_irqrestore(flags); |
a699449b JO |
2830 | skip: |
2831 | return true; | |
2832 | } | |
2833 | ||
2834 | /* | |
2835 | * Print out all remaining records to all consoles. | |
2836 | * | |
2837 | * @do_cond_resched is set by the caller. It can be true only in schedulable | |
2838 | * context. | |
2839 | * | |
2840 | * @next_seq is set to the sequence number after the last available record. | |
2841 | * The value is valid only when this function returns true. It means that all | |
2842 | * usable consoles are completely flushed. | |
2843 | * | |
2844 | * @handover will be set to true if a printk waiter has taken over the | |
2845 | * console_lock, in which case the caller is no longer holding the | |
2846 | * console_lock. Otherwise it is set to false. | |
2847 | * | |
2848 | * Returns true when there was at least one usable console and all messages | |
2849 | * were flushed to all usable consoles. A returned false informs the caller | |
2850 | * that everything was not flushed (either there were no usable consoles or | |
2851 | * another context has taken over printing or it is a panic situation and this | |
5831788a PM |
2852 | * is not the panic CPU). Regardless the reason, the caller should assume it |
2853 | * is not useful to immediately try again. | |
a699449b JO |
2854 | * |
2855 | * Requires the console_lock. | |
2856 | */ | |
2857 | static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handover) | |
2858 | { | |
03a749e6 JO |
2859 | static char dropped_text[DROPPED_TEXT_MAX]; |
2860 | static char ext_text[CONSOLE_EXT_LOG_MAX]; | |
2861 | static char text[CONSOLE_LOG_MAX]; | |
a699449b JO |
2862 | bool any_usable = false; |
2863 | struct console *con; | |
2864 | bool any_progress; | |
fc956ae0 | 2865 | int cookie; |
a699449b JO |
2866 | |
2867 | *next_seq = 0; | |
2868 | *handover = false; | |
2869 | ||
2870 | do { | |
2871 | any_progress = false; | |
2872 | ||
fc956ae0 JO |
2873 | cookie = console_srcu_read_lock(); |
2874 | for_each_console_srcu(con) { | |
a699449b JO |
2875 | bool progress; |
2876 | ||
2877 | if (!console_is_usable(con)) | |
2878 | continue; | |
2879 | any_usable = true; | |
2880 | ||
fc956ae0 | 2881 | if (console_srcu_read_flags(con) & CON_EXTENDED) { |
03a749e6 | 2882 | /* Extended consoles do not print "dropped messages". */ |
2d9ef940 PM |
2883 | progress = console_emit_next_record(con, &text[0], |
2884 | &ext_text[0], NULL, | |
fc956ae0 | 2885 | handover, cookie); |
03a749e6 | 2886 | } else { |
2d9ef940 PM |
2887 | progress = console_emit_next_record(con, &text[0], |
2888 | NULL, &dropped_text[0], | |
fc956ae0 | 2889 | handover, cookie); |
03a749e6 | 2890 | } |
fc956ae0 JO |
2891 | |
2892 | /* | |
2893 | * If a handover has occurred, the SRCU read lock | |
2894 | * is already released. | |
2895 | */ | |
a699449b JO |
2896 | if (*handover) |
2897 | return false; | |
2898 | ||
2899 | /* Track the next of the highest seq flushed. */ | |
2900 | if (con->seq > *next_seq) | |
2901 | *next_seq = con->seq; | |
2902 | ||
2903 | if (!progress) | |
2904 | continue; | |
2905 | any_progress = true; | |
2906 | ||
2907 | /* Allow panic_cpu to take over the consoles safely. */ | |
2908 | if (abandon_console_lock_in_panic()) | |
fc956ae0 | 2909 | goto abandon; |
a699449b JO |
2910 | |
2911 | if (do_cond_resched) | |
2912 | cond_resched(); | |
2913 | } | |
fc956ae0 | 2914 | console_srcu_read_unlock(cookie); |
a699449b JO |
2915 | } while (any_progress); |
2916 | ||
2917 | return any_usable; | |
fc956ae0 JO |
2918 | |
2919 | abandon: | |
2920 | console_srcu_read_unlock(cookie); | |
2921 | return false; | |
a8199371 SS |
2922 | } |
2923 | ||
1da177e4 | 2924 | /** |
848a9c10 | 2925 | * console_unlock - unblock the console subsystem from printing |
1da177e4 | 2926 | * |
848a9c10 JO |
2927 | * Releases the console_lock which the caller holds to block printing of |
2928 | * the console subsystem. | |
1da177e4 | 2929 | * |
ac751efa TH |
2930 | * While the console_lock was held, console output may have been buffered |
2931 | * by printk(). If this is the case, console_unlock(); emits | |
2932 | * the output prior to releasing the lock. | |
1da177e4 | 2933 | * |
ac751efa | 2934 | * console_unlock(); may be called from any context. |
1da177e4 | 2935 | */ |
ac751efa | 2936 | void console_unlock(void) |
1da177e4 | 2937 | { |
a699449b JO |
2938 | bool do_cond_resched; |
2939 | bool handover; | |
2940 | bool flushed; | |
2941 | u64 next_seq; | |
1da177e4 | 2942 | |
557240b4 | 2943 | if (console_suspended) { |
bd8d7cf5 | 2944 | up_console_sem(); |
557240b4 LT |
2945 | return; |
2946 | } | |
78944e54 | 2947 | |
8d91f8b1 | 2948 | /* |
257ab443 | 2949 | * Console drivers are called with interrupts disabled, so |
8d91f8b1 TH |
2950 | * @console_may_schedule should be cleared before; however, we may |
2951 | * end up dumping a lot of lines, for example, if called from | |
2952 | * console registration path, and should invoke cond_resched() | |
2953 | * between lines if allowable. Not doing so can cause a very long | |
2954 | * scheduling stall on a slow console leading to RCU stall and | |
2955 | * softlockup warnings which exacerbate the issue with more | |
a699449b JO |
2956 | * messages practically incapacitating the system. Therefore, create |
2957 | * a local to use for the printing loop. | |
8d91f8b1 TH |
2958 | */ |
2959 | do_cond_resched = console_may_schedule; | |
78944e54 | 2960 | |
a699449b JO |
2961 | do { |
2962 | console_may_schedule = 0; | |
649e6ee3 | 2963 | |
a699449b JO |
2964 | flushed = console_flush_all(do_cond_resched, &next_seq, &handover); |
2965 | if (!handover) | |
2966 | __console_unlock(); | |
f92b070f | 2967 | |
896fbe20 | 2968 | /* |
a699449b JO |
2969 | * Abort if there was a failure to flush all messages to all |
2970 | * usable consoles. Either it is not possible to flush (in | |
2971 | * which case it would be an infinite loop of retrying) or | |
2972 | * another context has taken over printing. | |
896fbe20 | 2973 | */ |
a699449b JO |
2974 | if (!flushed) |
2975 | break; | |
7ff9554b | 2976 | |
dbdda842 | 2977 | /* |
a699449b JO |
2978 | * Some context may have added new records after |
2979 | * console_flush_all() but before unlocking the console. | |
2980 | * Re-check if there is a new record to flush. If the trylock | |
2981 | * fails, another context is already handling the printing. | |
dbdda842 | 2982 | */ |
a699449b | 2983 | } while (prb_read_valid(prb, next_seq, NULL) && console_trylock()); |
1da177e4 | 2984 | } |
ac751efa | 2985 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 2986 | |
ddad86c2 MW |
2987 | /** |
2988 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
2989 | * |
2990 | * If the console code is currently allowed to sleep, and | |
2991 | * if this CPU should yield the CPU to another task, do | |
2992 | * so here. | |
2993 | * | |
ac751efa | 2994 | * Must be called within console_lock();. |
1da177e4 LT |
2995 | */ |
2996 | void __sched console_conditional_schedule(void) | |
2997 | { | |
2998 | if (console_may_schedule) | |
2999 | cond_resched(); | |
3000 | } | |
3001 | EXPORT_SYMBOL(console_conditional_schedule); | |
3002 | ||
1da177e4 LT |
3003 | void console_unblank(void) |
3004 | { | |
3005 | struct console *c; | |
d792db6f | 3006 | int cookie; |
1da177e4 LT |
3007 | |
3008 | /* | |
d792db6f JO |
3009 | * Stop console printing because the unblank() callback may |
3010 | * assume the console is not within its write() callback. | |
3011 | * | |
3012 | * If @oops_in_progress is set, this may be an atomic context. | |
3013 | * In that case, attempt a trylock as best-effort. | |
1da177e4 LT |
3014 | */ |
3015 | if (oops_in_progress) { | |
bd8d7cf5 | 3016 | if (down_trylock_console_sem() != 0) |
1da177e4 LT |
3017 | return; |
3018 | } else | |
ac751efa | 3019 | console_lock(); |
1da177e4 | 3020 | |
007eeab7 | 3021 | console_locked = 1; |
1da177e4 | 3022 | console_may_schedule = 0; |
d792db6f JO |
3023 | |
3024 | cookie = console_srcu_read_lock(); | |
3025 | for_each_console_srcu(c) { | |
3026 | if ((console_srcu_read_flags(c) & CON_ENABLED) && c->unblank) | |
1da177e4 | 3027 | c->unblank(); |
d792db6f JO |
3028 | } |
3029 | console_srcu_read_unlock(cookie); | |
3030 | ||
ac751efa | 3031 | console_unlock(); |
3b604ca8 JO |
3032 | |
3033 | if (!oops_in_progress) | |
3034 | pr_flush(1000, true); | |
1da177e4 | 3035 | } |
1da177e4 | 3036 | |
8d91f8b1 TH |
3037 | /** |
3038 | * console_flush_on_panic - flush console content on panic | |
de6da1e8 | 3039 | * @mode: flush all messages in buffer or just the pending ones |
8d91f8b1 TH |
3040 | * |
3041 | * Immediately output all pending messages no matter what. | |
3042 | */ | |
de6da1e8 | 3043 | void console_flush_on_panic(enum con_flush_mode mode) |
8d91f8b1 TH |
3044 | { |
3045 | /* | |
3046 | * If someone else is holding the console lock, trylock will fail | |
3047 | * and may_schedule may be set. Ignore and proceed to unlock so | |
3048 | * that messages are flushed out. As this can be called from any | |
3049 | * context and we don't want to get preempted while flushing, | |
3050 | * ensure may_schedule is cleared. | |
3051 | */ | |
3052 | console_trylock(); | |
3053 | console_may_schedule = 0; | |
de6da1e8 | 3054 | |
a699449b JO |
3055 | if (mode == CONSOLE_REPLAY_ALL) { |
3056 | struct console *c; | |
87f2e4b7 | 3057 | int cookie; |
a699449b JO |
3058 | u64 seq; |
3059 | ||
3060 | seq = prb_first_valid_seq(prb); | |
87f2e4b7 JO |
3061 | |
3062 | cookie = console_srcu_read_lock(); | |
3063 | for_each_console_srcu(c) { | |
3064 | /* | |
3065 | * If the above console_trylock() failed, this is an | |
3066 | * unsynchronized assignment. But in that case, the | |
3067 | * kernel is in "hope and pray" mode anyway. | |
3068 | */ | |
a699449b | 3069 | c->seq = seq; |
87f2e4b7 JO |
3070 | } |
3071 | console_srcu_read_unlock(cookie); | |
a699449b | 3072 | } |
8d91f8b1 TH |
3073 | console_unlock(); |
3074 | } | |
3075 | ||
1da177e4 LT |
3076 | /* |
3077 | * Return the console tty driver structure and its associated index | |
3078 | */ | |
3079 | struct tty_driver *console_device(int *index) | |
3080 | { | |
3081 | struct console *c; | |
3082 | struct tty_driver *driver = NULL; | |
8cb15f7f | 3083 | int cookie; |
1da177e4 | 3084 | |
8cb15f7f JO |
3085 | /* |
3086 | * Take console_lock to serialize device() callback with | |
3087 | * other console operations. For example, fg_console is | |
3088 | * modified under console_lock when switching vt. | |
3089 | */ | |
ac751efa | 3090 | console_lock(); |
8cb15f7f JO |
3091 | |
3092 | cookie = console_srcu_read_lock(); | |
3093 | for_each_console_srcu(c) { | |
1da177e4 LT |
3094 | if (!c->device) |
3095 | continue; | |
3096 | driver = c->device(c, index); | |
3097 | if (driver) | |
3098 | break; | |
3099 | } | |
8cb15f7f JO |
3100 | console_srcu_read_unlock(cookie); |
3101 | ||
ac751efa | 3102 | console_unlock(); |
1da177e4 LT |
3103 | return driver; |
3104 | } | |
3105 | ||
3106 | /* | |
3107 | * Prevent further output on the passed console device so that (for example) | |
3108 | * serial drivers can disable console output before suspending a port, and can | |
3109 | * re-enable output afterwards. | |
3110 | */ | |
3111 | void console_stop(struct console *console) | |
3112 | { | |
3b604ca8 | 3113 | __pr_flush(console, 1000, true); |
4dc64682 | 3114 | console_list_lock(); |
100bdef2 | 3115 | console_srcu_write_flags(console, console->flags & ~CON_ENABLED); |
4dc64682 | 3116 | console_list_unlock(); |
6c4afa79 JO |
3117 | |
3118 | /* | |
3119 | * Ensure that all SRCU list walks have completed. All contexts must | |
3120 | * be able to see that this console is disabled so that (for example) | |
3121 | * the caller can suspend the port without risk of another context | |
3122 | * using the port. | |
3123 | */ | |
3124 | synchronize_srcu(&console_srcu); | |
1da177e4 LT |
3125 | } |
3126 | EXPORT_SYMBOL(console_stop); | |
3127 | ||
3128 | void console_start(struct console *console) | |
3129 | { | |
4dc64682 | 3130 | console_list_lock(); |
100bdef2 | 3131 | console_srcu_write_flags(console, console->flags | CON_ENABLED); |
4dc64682 | 3132 | console_list_unlock(); |
3b604ca8 | 3133 | __pr_flush(console, 1000, true); |
1da177e4 LT |
3134 | } |
3135 | EXPORT_SYMBOL(console_start); | |
3136 | ||
7bf69395 FDN |
3137 | static int __read_mostly keep_bootcon; |
3138 | ||
3139 | static int __init keep_bootcon_setup(char *str) | |
3140 | { | |
3141 | keep_bootcon = 1; | |
27083bac | 3142 | pr_info("debug: skip boot console de-registration.\n"); |
7bf69395 FDN |
3143 | |
3144 | return 0; | |
3145 | } | |
3146 | ||
3147 | early_param("keep_bootcon", keep_bootcon_setup); | |
3148 | ||
ad8cd1db BH |
3149 | /* |
3150 | * This is called by register_console() to try to match | |
3151 | * the newly registered console with any of the ones selected | |
3152 | * by either the command line or add_preferred_console() and | |
3153 | * setup/enable it. | |
3154 | * | |
3155 | * Care need to be taken with consoles that are statically | |
3156 | * enabled such as netconsole | |
3157 | */ | |
ed758b30 PM |
3158 | static int try_enable_preferred_console(struct console *newcon, |
3159 | bool user_specified) | |
ad8cd1db BH |
3160 | { |
3161 | struct console_cmdline *c; | |
bba18a1a | 3162 | int i, err; |
ad8cd1db BH |
3163 | |
3164 | for (i = 0, c = console_cmdline; | |
3165 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
3166 | i++, c++) { | |
e369d822 BH |
3167 | if (c->user_specified != user_specified) |
3168 | continue; | |
ad8cd1db BH |
3169 | if (!newcon->match || |
3170 | newcon->match(newcon, c->name, c->index, c->options) != 0) { | |
3171 | /* default matching */ | |
3172 | BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name)); | |
3173 | if (strcmp(c->name, newcon->name) != 0) | |
3174 | continue; | |
3175 | if (newcon->index >= 0 && | |
3176 | newcon->index != c->index) | |
3177 | continue; | |
3178 | if (newcon->index < 0) | |
3179 | newcon->index = c->index; | |
3180 | ||
3181 | if (_braille_register_console(newcon, c)) | |
3182 | return 0; | |
3183 | ||
3184 | if (newcon->setup && | |
bba18a1a AS |
3185 | (err = newcon->setup(newcon, c->options)) != 0) |
3186 | return err; | |
ad8cd1db BH |
3187 | } |
3188 | newcon->flags |= CON_ENABLED; | |
f873efe8 | 3189 | if (i == preferred_console) |
ad8cd1db | 3190 | newcon->flags |= CON_CONSDEV; |
ad8cd1db BH |
3191 | return 0; |
3192 | } | |
3193 | ||
3194 | /* | |
3195 | * Some consoles, such as pstore and netconsole, can be enabled even | |
e369d822 | 3196 | * without matching. Accept the pre-enabled consoles only when match() |
50460376 | 3197 | * and setup() had a chance to be called. |
ad8cd1db | 3198 | */ |
e369d822 | 3199 | if (newcon->flags & CON_ENABLED && c->user_specified == user_specified) |
ad8cd1db BH |
3200 | return 0; |
3201 | ||
3202 | return -ENOENT; | |
3203 | } | |
3204 | ||
ed758b30 PM |
3205 | /* Try to enable the console unconditionally */ |
3206 | static void try_enable_default_console(struct console *newcon) | |
3207 | { | |
3208 | if (newcon->index < 0) | |
3209 | newcon->index = 0; | |
3210 | ||
3211 | if (newcon->setup && newcon->setup(newcon, NULL) != 0) | |
3212 | return; | |
3213 | ||
3214 | newcon->flags |= CON_ENABLED; | |
3215 | ||
4f546939 | 3216 | if (newcon->device) |
ed758b30 | 3217 | newcon->flags |= CON_CONSDEV; |
ed758b30 PM |
3218 | } |
3219 | ||
1fc0ca9e JO |
3220 | #define con_printk(lvl, con, fmt, ...) \ |
3221 | printk(lvl pr_fmt("%sconsole [%s%d] " fmt), \ | |
3222 | (con->flags & CON_BOOT) ? "boot" : "", \ | |
3223 | con->name, con->index, ##__VA_ARGS__) | |
3224 | ||
a4242760 | 3225 | static void console_init_seq(struct console *newcon, bool bootcon_registered) |
b80ea0e8 | 3226 | { |
a4242760 JO |
3227 | struct console *con; |
3228 | bool handover; | |
3229 | ||
3230 | if (newcon->flags & (CON_PRINTBUFFER | CON_BOOT)) { | |
b80ea0e8 JO |
3231 | /* Get a consistent copy of @syslog_seq. */ |
3232 | mutex_lock(&syslog_lock); | |
3233 | newcon->seq = syslog_seq; | |
3234 | mutex_unlock(&syslog_lock); | |
3235 | } else { | |
a4242760 | 3236 | /* Begin with next message added to ringbuffer. */ |
b80ea0e8 | 3237 | newcon->seq = prb_next_seq(prb); |
a4242760 JO |
3238 | |
3239 | /* | |
3240 | * If any enabled boot consoles are due to be unregistered | |
3241 | * shortly, some may not be caught up and may be the same | |
3242 | * device as @newcon. Since it is not known which boot console | |
3243 | * is the same device, flush all consoles and, if necessary, | |
3244 | * start with the message of the enabled boot console that is | |
3245 | * the furthest behind. | |
3246 | */ | |
3247 | if (bootcon_registered && !keep_bootcon) { | |
848a9c10 JO |
3248 | /* |
3249 | * Hold the console_lock to stop console printing and | |
3250 | * guarantee safe access to console->seq. | |
3251 | */ | |
3252 | console_lock(); | |
3253 | ||
a4242760 JO |
3254 | /* |
3255 | * Flush all consoles and set the console to start at | |
3256 | * the next unprinted sequence number. | |
3257 | */ | |
3258 | if (!console_flush_all(true, &newcon->seq, &handover)) { | |
3259 | /* | |
3260 | * Flushing failed. Just choose the lowest | |
3261 | * sequence of the enabled boot consoles. | |
3262 | */ | |
3263 | ||
3264 | /* | |
3265 | * If there was a handover, this context no | |
3266 | * longer holds the console_lock. | |
3267 | */ | |
3268 | if (handover) | |
3269 | console_lock(); | |
3270 | ||
3271 | newcon->seq = prb_next_seq(prb); | |
3272 | for_each_console(con) { | |
3273 | if ((con->flags & CON_BOOT) && | |
3274 | (con->flags & CON_ENABLED) && | |
3275 | con->seq < newcon->seq) { | |
3276 | newcon->seq = con->seq; | |
3277 | } | |
3278 | } | |
3279 | } | |
848a9c10 JO |
3280 | |
3281 | console_unlock(); | |
a4242760 | 3282 | } |
b80ea0e8 JO |
3283 | } |
3284 | } | |
3285 | ||
d9a4af56 TG |
3286 | #define console_first() \ |
3287 | hlist_entry(console_list.first, struct console, node) | |
3288 | ||
4dc64682 JO |
3289 | static int unregister_console_locked(struct console *console); |
3290 | ||
1da177e4 LT |
3291 | /* |
3292 | * The console driver calls this routine during kernel initialization | |
3293 | * to register the console printing procedure with printk() and to | |
3294 | * print any messages that were printed by the kernel before the | |
3295 | * console driver was initialized. | |
4d091611 RG |
3296 | * |
3297 | * This can happen pretty early during the boot process (because of | |
3298 | * early_printk) - sometimes before setup_arch() completes - be careful | |
3299 | * of what kernel features are used - they may not be initialised yet. | |
3300 | * | |
3301 | * There are two types of consoles - bootconsoles (early_printk) and | |
3302 | * "real" consoles (everything which is not a bootconsole) which are | |
3303 | * handled differently. | |
3304 | * - Any number of bootconsoles can be registered at any time. | |
3305 | * - As soon as a "real" console is registered, all bootconsoles | |
3306 | * will be unregistered automatically. | |
3307 | * - Once a "real" console is registered, any attempt to register a | |
3308 | * bootconsoles will be rejected | |
1da177e4 | 3309 | */ |
4d091611 | 3310 | void register_console(struct console *newcon) |
1da177e4 | 3311 | { |
5e8ba485 | 3312 | struct console *con; |
11457036 JO |
3313 | bool bootcon_registered = false; |
3314 | bool realcon_registered = false; | |
ad8cd1db | 3315 | int err; |
1da177e4 | 3316 | |
4dc64682 JO |
3317 | console_list_lock(); |
3318 | ||
5e8ba485 PM |
3319 | for_each_console(con) { |
3320 | if (WARN(con == newcon, "console '%s%d' already registered\n", | |
4dc64682 JO |
3321 | con->name, con->index)) { |
3322 | goto unlock; | |
3323 | } | |
16cf48a6 | 3324 | |
5e8ba485 | 3325 | if (con->flags & CON_BOOT) |
11457036 | 3326 | bootcon_registered = true; |
5e8ba485 | 3327 | else |
11457036 | 3328 | realcon_registered = true; |
69331af7 GH |
3329 | } |
3330 | ||
5e8ba485 | 3331 | /* Do not register boot consoles when there already is a real one. */ |
11457036 | 3332 | if ((newcon->flags & CON_BOOT) && realcon_registered) { |
5e8ba485 PM |
3333 | pr_info("Too late to register bootconsole %s%d\n", |
3334 | newcon->name, newcon->index); | |
4dc64682 | 3335 | goto unlock; |
5e8ba485 | 3336 | } |
4d091611 | 3337 | |
1da177e4 | 3338 | /* |
4f546939 PM |
3339 | * See if we want to enable this console driver by default. |
3340 | * | |
3341 | * Nope when a console is preferred by the command line, device | |
3342 | * tree, or SPCR. | |
3343 | * | |
3344 | * The first real console with tty binding (driver) wins. More | |
3345 | * consoles might get enabled before the right one is found. | |
3346 | * | |
3347 | * Note that a console with tty binding will have CON_CONSDEV | |
3348 | * flag set and will be first in the list. | |
1da177e4 | 3349 | */ |
4f546939 | 3350 | if (preferred_console < 0) { |
d9a4af56 TG |
3351 | if (hlist_empty(&console_list) || !console_first()->device || |
3352 | console_first()->flags & CON_BOOT) { | |
4f546939 PM |
3353 | try_enable_default_console(newcon); |
3354 | } | |
3355 | } | |
1da177e4 | 3356 | |
e369d822 | 3357 | /* See if this console matches one we selected on the command line */ |
ed758b30 | 3358 | err = try_enable_preferred_console(newcon, true); |
bbeddf52 | 3359 | |
e369d822 BH |
3360 | /* If not, try to match against the platform default(s) */ |
3361 | if (err == -ENOENT) | |
ed758b30 | 3362 | err = try_enable_preferred_console(newcon, false); |
1da177e4 | 3363 | |
ad8cd1db BH |
3364 | /* printk() messages are not printed to the Braille console. */ |
3365 | if (err || newcon->flags & CON_BRL) | |
4dc64682 | 3366 | goto unlock; |
1da177e4 | 3367 | |
8259cf43 RG |
3368 | /* |
3369 | * If we have a bootconsole, and are switching to a real console, | |
3370 | * don't print everything out again, since when the boot console, and | |
3371 | * the real console are the same physical device, it's annoying to | |
3372 | * see the beginning boot messages twice | |
3373 | */ | |
11457036 | 3374 | if (bootcon_registered && |
5e8ba485 | 3375 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) { |
4d091611 | 3376 | newcon->flags &= ~CON_PRINTBUFFER; |
5e8ba485 | 3377 | } |
1da177e4 | 3378 | |
6c4afa79 | 3379 | newcon->dropped = 0; |
a4242760 | 3380 | console_init_seq(newcon, bootcon_registered); |
6c4afa79 | 3381 | |
1da177e4 | 3382 | /* |
d9a4af56 TG |
3383 | * Put this console in the list - keep the |
3384 | * preferred driver at the head of the list. | |
1da177e4 | 3385 | */ |
d9a4af56 TG |
3386 | if (hlist_empty(&console_list)) { |
3387 | /* Ensure CON_CONSDEV is always set for the head. */ | |
33225d7b | 3388 | newcon->flags |= CON_CONSDEV; |
6c4afa79 | 3389 | hlist_add_head_rcu(&newcon->node, &console_list); |
d9a4af56 TG |
3390 | |
3391 | } else if (newcon->flags & CON_CONSDEV) { | |
3392 | /* Only the new head can have CON_CONSDEV set. */ | |
100bdef2 | 3393 | console_srcu_write_flags(console_first(), console_first()->flags & ~CON_CONSDEV); |
6c4afa79 | 3394 | hlist_add_head_rcu(&newcon->node, &console_list); |
6fe29354 | 3395 | |
a699449b | 3396 | } else { |
6c4afa79 | 3397 | hlist_add_behind_rcu(&newcon->node, console_list.first); |
1da177e4 | 3398 | } |
6c4afa79 JO |
3399 | |
3400 | /* | |
3401 | * No need to synchronize SRCU here! The caller does not rely | |
3402 | * on all contexts being able to see the new console before | |
3403 | * register_console() completes. | |
3404 | */ | |
3405 | ||
fbc92a34 | 3406 | console_sysfs_notify(); |
8259cf43 RG |
3407 | |
3408 | /* | |
3409 | * By unregistering the bootconsoles after we enable the real console | |
3410 | * we get the "console xxx enabled" message on all the consoles - | |
3411 | * boot consoles, real consoles, etc - this is to ensure that end | |
3412 | * users know there might be something in the kernel's log buffer that | |
3413 | * went to the bootconsole (that they do not see on the real console) | |
3414 | */ | |
1fc0ca9e | 3415 | con_printk(KERN_INFO, newcon, "enabled\n"); |
11457036 | 3416 | if (bootcon_registered && |
7bf69395 FDN |
3417 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && |
3418 | !keep_bootcon) { | |
d9a4af56 TG |
3419 | struct hlist_node *tmp; |
3420 | ||
3421 | hlist_for_each_entry_safe(con, tmp, &console_list, node) { | |
5e8ba485 | 3422 | if (con->flags & CON_BOOT) |
4dc64682 | 3423 | unregister_console_locked(con); |
d9a4af56 | 3424 | } |
8259cf43 | 3425 | } |
4dc64682 JO |
3426 | unlock: |
3427 | console_list_unlock(); | |
1da177e4 LT |
3428 | } |
3429 | EXPORT_SYMBOL(register_console); | |
3430 | ||
4dc64682 JO |
3431 | /* Must be called under console_list_lock(). */ |
3432 | static int unregister_console_locked(struct console *console) | |
1da177e4 | 3433 | { |
bbeddf52 | 3434 | int res; |
1da177e4 | 3435 | |
4dc64682 JO |
3436 | lockdep_assert_console_list_lock_held(); |
3437 | ||
1fc0ca9e | 3438 | con_printk(KERN_INFO, console, "disabled\n"); |
6b802394 | 3439 | |
bbeddf52 | 3440 | res = _braille_unregister_console(console); |
bb72e398 | 3441 | if (res < 0) |
bbeddf52 | 3442 | return res; |
bb72e398 AS |
3443 | if (res > 0) |
3444 | return 0; | |
f7511d5f | 3445 | |
d9a4af56 | 3446 | /* Disable it unconditionally */ |
100bdef2 | 3447 | console_srcu_write_flags(console, console->flags & ~CON_ENABLED); |
d9a4af56 | 3448 | |
848a9c10 | 3449 | if (!console_is_registered_locked(console)) |
d9a4af56 | 3450 | return -ENODEV; |
40dc5651 | 3451 | |
6c4afa79 | 3452 | hlist_del_init_rcu(&console->node); |
e78bedbd | 3453 | |
69331af7 | 3454 | /* |
d9a4af56 | 3455 | * <HISTORICAL> |
ab4af03a GE |
3456 | * If this isn't the last console and it has CON_CONSDEV set, we |
3457 | * need to set it on the next preferred console. | |
d9a4af56 TG |
3458 | * </HISTORICAL> |
3459 | * | |
3460 | * The above makes no sense as there is no guarantee that the next | |
3461 | * console has any device attached. Oh well.... | |
1da177e4 | 3462 | */ |
d9a4af56 | 3463 | if (!hlist_empty(&console_list) && console->flags & CON_CONSDEV) |
100bdef2 | 3464 | console_srcu_write_flags(console_first(), console_first()->flags | CON_CONSDEV); |
1da177e4 | 3465 | |
6c4afa79 JO |
3466 | /* |
3467 | * Ensure that all SRCU list walks have completed. All contexts | |
3468 | * must not be able to see this console in the list so that any | |
3469 | * exit/cleanup routines can be performed safely. | |
3470 | */ | |
3471 | synchronize_srcu(&console_srcu); | |
1da177e4 | 3472 | |
fbc92a34 | 3473 | console_sysfs_notify(); |
e78bedbd | 3474 | |
ed31685c AS |
3475 | if (console->exit) |
3476 | res = console->exit(console); | |
3477 | ||
e78bedbd | 3478 | return res; |
1da177e4 | 3479 | } |
e78bedbd | 3480 | |
4dc64682 JO |
3481 | int unregister_console(struct console *console) |
3482 | { | |
3483 | int res; | |
e78bedbd | 3484 | |
4dc64682 JO |
3485 | console_list_lock(); |
3486 | res = unregister_console_locked(console); | |
3487 | console_list_unlock(); | |
1da177e4 LT |
3488 | return res; |
3489 | } | |
3490 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 3491 | |
6f883675 JO |
3492 | /** |
3493 | * console_force_preferred_locked - force a registered console preferred | |
3494 | * @con: The registered console to force preferred. | |
3495 | * | |
3496 | * Must be called under console_list_lock(). | |
3497 | */ | |
3498 | void console_force_preferred_locked(struct console *con) | |
3499 | { | |
3500 | struct console *cur_pref_con; | |
3501 | ||
3502 | if (!console_is_registered_locked(con)) | |
3503 | return; | |
3504 | ||
3505 | cur_pref_con = console_first(); | |
3506 | ||
3507 | /* Already preferred? */ | |
3508 | if (cur_pref_con == con) | |
3509 | return; | |
3510 | ||
3511 | /* | |
3512 | * Delete, but do not re-initialize the entry. This allows the console | |
3513 | * to continue to appear registered (via any hlist_unhashed_lockless() | |
3514 | * checks), even though it was briefly removed from the console list. | |
3515 | */ | |
3516 | hlist_del_rcu(&con->node); | |
3517 | ||
3518 | /* | |
3519 | * Ensure that all SRCU list walks have completed so that the console | |
3520 | * can be added to the beginning of the console list and its forward | |
3521 | * list pointer can be re-initialized. | |
3522 | */ | |
3523 | synchronize_srcu(&console_srcu); | |
3524 | ||
3525 | con->flags |= CON_CONSDEV; | |
3526 | WARN_ON(!con->device); | |
3527 | ||
3528 | /* Only the new head can have CON_CONSDEV set. */ | |
3529 | console_srcu_write_flags(cur_pref_con, cur_pref_con->flags & ~CON_CONSDEV); | |
3530 | hlist_add_head_rcu(&con->node, &console_list); | |
3531 | } | |
3532 | EXPORT_SYMBOL(console_force_preferred_locked); | |
3533 | ||
0c688614 NP |
3534 | /* |
3535 | * Initialize the console device. This is called *early*, so | |
3536 | * we can't necessarily depend on lots of kernel help here. | |
3537 | * Just do some early initializations, and do the complex setup | |
3538 | * later. | |
3539 | */ | |
3540 | void __init console_init(void) | |
3541 | { | |
58eacfff | 3542 | int ret; |
1b1eeca7 AB |
3543 | initcall_t call; |
3544 | initcall_entry_t *ce; | |
0c688614 NP |
3545 | |
3546 | /* Setup the default TTY line discipline. */ | |
3547 | n_tty_init(); | |
3548 | ||
3549 | /* | |
3550 | * set up the console device so that later boot sequences can | |
3551 | * inform about problems etc.. | |
3552 | */ | |
1b1eeca7 | 3553 | ce = __con_initcall_start; |
58eacfff | 3554 | trace_initcall_level("console"); |
1b1eeca7 AB |
3555 | while (ce < __con_initcall_end) { |
3556 | call = initcall_from_entry(ce); | |
3557 | trace_initcall_start(call); | |
3558 | ret = call(); | |
3559 | trace_initcall_finish(call, ret); | |
3560 | ce++; | |
0c688614 NP |
3561 | } |
3562 | } | |
3563 | ||
81cc26f2 TR |
3564 | /* |
3565 | * Some boot consoles access data that is in the init section and which will | |
3566 | * be discarded after the initcalls have been run. To make sure that no code | |
3567 | * will access this data, unregister the boot consoles in a late initcall. | |
3568 | * | |
3569 | * If for some reason, such as deferred probe or the driver being a loadable | |
3570 | * module, the real console hasn't registered yet at this point, there will | |
3571 | * be a brief interval in which no messages are logged to the console, which | |
3572 | * makes it difficult to diagnose problems that occur during this time. | |
3573 | * | |
3574 | * To mitigate this problem somewhat, only unregister consoles whose memory | |
2b1be689 | 3575 | * intersects with the init section. Note that all other boot consoles will |
acebb559 | 3576 | * get unregistered when the real preferred console is registered. |
81cc26f2 | 3577 | */ |
034260d6 | 3578 | static int __init printk_late_init(void) |
0c5564bd | 3579 | { |
d9a4af56 | 3580 | struct hlist_node *tmp; |
4d091611 | 3581 | struct console *con; |
90b14889 | 3582 | int ret; |
4d091611 | 3583 | |
4dc64682 | 3584 | console_list_lock(); |
d9a4af56 | 3585 | hlist_for_each_entry_safe(con, tmp, &console_list, node) { |
5a814231 PM |
3586 | if (!(con->flags & CON_BOOT)) |
3587 | continue; | |
3588 | ||
3589 | /* Check addresses that might be used for enabled consoles. */ | |
3590 | if (init_section_intersects(con, sizeof(*con)) || | |
3591 | init_section_contains(con->write, 0) || | |
3592 | init_section_contains(con->read, 0) || | |
3593 | init_section_contains(con->device, 0) || | |
3594 | init_section_contains(con->unblank, 0) || | |
3595 | init_section_contains(con->data, 0)) { | |
81cc26f2 | 3596 | /* |
2b1be689 MR |
3597 | * Please, consider moving the reported consoles out |
3598 | * of the init section. | |
81cc26f2 | 3599 | */ |
2b1be689 MR |
3600 | pr_warn("bootconsole [%s%d] uses init memory and must be disabled even before the real one is ready\n", |
3601 | con->name, con->index); | |
4dc64682 | 3602 | unregister_console_locked(con); |
cb00e99c | 3603 | } |
0c5564bd | 3604 | } |
4dc64682 | 3605 | console_list_unlock(); |
d9a4af56 | 3606 | |
90b14889 SAS |
3607 | ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL, |
3608 | console_cpu_notify); | |
3609 | WARN_ON(ret < 0); | |
3610 | ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "printk:online", | |
3611 | console_cpu_notify, NULL); | |
3612 | WARN_ON(ret < 0); | |
faaa357a | 3613 | printk_sysctl_init(); |
0c5564bd RG |
3614 | return 0; |
3615 | } | |
034260d6 | 3616 | late_initcall(printk_late_init); |
0c5564bd | 3617 | |
7ef3d2fd | 3618 | #if defined CONFIG_PRINTK |
3b604ca8 JO |
3619 | /* If @con is specified, only wait for that console. Otherwise wait for all. */ |
3620 | static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) | |
3621 | { | |
3622 | int remaining = timeout_ms; | |
3623 | struct console *c; | |
3624 | u64 last_diff = 0; | |
3625 | u64 printk_seq; | |
eb7f1ed2 | 3626 | int cookie; |
3b604ca8 JO |
3627 | u64 diff; |
3628 | u64 seq; | |
3629 | ||
3630 | might_sleep(); | |
3631 | ||
3632 | seq = prb_next_seq(prb); | |
3633 | ||
3634 | for (;;) { | |
3635 | diff = 0; | |
3636 | ||
eb7f1ed2 JO |
3637 | /* |
3638 | * Hold the console_lock to guarantee safe access to | |
3639 | * console->seq and to prevent changes to @console_suspended | |
3640 | * until all consoles have been processed. | |
3641 | */ | |
3b604ca8 | 3642 | console_lock(); |
9023ca08 | 3643 | |
eb7f1ed2 JO |
3644 | cookie = console_srcu_read_lock(); |
3645 | for_each_console_srcu(c) { | |
3b604ca8 JO |
3646 | if (con && con != c) |
3647 | continue; | |
3648 | if (!console_is_usable(c)) | |
3649 | continue; | |
3650 | printk_seq = c->seq; | |
3651 | if (printk_seq < seq) | |
3652 | diff += seq - printk_seq; | |
3653 | } | |
eb7f1ed2 | 3654 | console_srcu_read_unlock(cookie); |
3b604ca8 | 3655 | |
9023ca08 JO |
3656 | /* |
3657 | * If consoles are suspended, it cannot be expected that they | |
3658 | * make forward progress, so timeout immediately. @diff is | |
3659 | * still used to return a valid flush status. | |
3660 | */ | |
3661 | if (console_suspended) | |
3662 | remaining = 0; | |
3663 | else if (diff != last_diff && reset_on_progress) | |
3b604ca8 JO |
3664 | remaining = timeout_ms; |
3665 | ||
9023ca08 JO |
3666 | console_unlock(); |
3667 | ||
3b604ca8 JO |
3668 | if (diff == 0 || remaining == 0) |
3669 | break; | |
3670 | ||
3671 | if (remaining < 0) { | |
3672 | /* no timeout limit */ | |
3673 | msleep(100); | |
3674 | } else if (remaining < 100) { | |
3675 | msleep(remaining); | |
3676 | remaining = 0; | |
3677 | } else { | |
3678 | msleep(100); | |
3679 | remaining -= 100; | |
3680 | } | |
3681 | ||
3682 | last_diff = diff; | |
3683 | } | |
3684 | ||
3685 | return (diff == 0); | |
3686 | } | |
3687 | ||
3688 | /** | |
3689 | * pr_flush() - Wait for printing threads to catch up. | |
3690 | * | |
3691 | * @timeout_ms: The maximum time (in ms) to wait. | |
3692 | * @reset_on_progress: Reset the timeout if forward progress is seen. | |
3693 | * | |
3694 | * A value of 0 for @timeout_ms means no waiting will occur. A value of -1 | |
3695 | * represents infinite waiting. | |
3696 | * | |
3697 | * If @reset_on_progress is true, the timeout will be reset whenever any | |
3698 | * printer has been seen to make some forward progress. | |
3699 | * | |
3700 | * Context: Process context. May sleep while acquiring console lock. | |
3701 | * Return: true if all enabled printers are caught up. | |
3702 | */ | |
c60ba2d3 | 3703 | static bool pr_flush(int timeout_ms, bool reset_on_progress) |
3b604ca8 JO |
3704 | { |
3705 | return __pr_flush(NULL, timeout_ms, reset_on_progress); | |
3706 | } | |
3b604ca8 | 3707 | |
dc72c32e FW |
3708 | /* |
3709 | * Delayed printk version, for scheduler-internal messages: | |
3710 | */ | |
5831788a PM |
3711 | #define PRINTK_PENDING_WAKEUP 0x01 |
3712 | #define PRINTK_PENDING_OUTPUT 0x02 | |
dc72c32e FW |
3713 | |
3714 | static DEFINE_PER_CPU(int, printk_pending); | |
dc72c32e FW |
3715 | |
3716 | static void wake_up_klogd_work_func(struct irq_work *irq_work) | |
3717 | { | |
2ba3673d | 3718 | int pending = this_cpu_xchg(printk_pending, 0); |
dc72c32e | 3719 | |
5831788a | 3720 | if (pending & PRINTK_PENDING_OUTPUT) { |
458df9fd SR |
3721 | /* If trylock fails, someone else is doing the printing */ |
3722 | if (console_trylock()) | |
3723 | console_unlock(); | |
dc72c32e FW |
3724 | } |
3725 | ||
3726 | if (pending & PRINTK_PENDING_WAKEUP) | |
809631e2 | 3727 | wake_up_interruptible(&log_wait); |
dc72c32e FW |
3728 | } |
3729 | ||
7a9f50a0 PZ |
3730 | static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = |
3731 | IRQ_WORK_INIT_LAZY(wake_up_klogd_work_func); | |
dc72c32e | 3732 | |
5341b93d | 3733 | static void __wake_up_klogd(int val) |
dc72c32e | 3734 | { |
ab6f762f SS |
3735 | if (!printk_percpu_data_ready()) |
3736 | return; | |
3737 | ||
dc72c32e | 3738 | preempt_disable(); |
1f5d7830 JO |
3739 | /* |
3740 | * Guarantee any new records can be seen by tasks preparing to wait | |
3741 | * before this context checks if the wait queue is empty. | |
3742 | * | |
3743 | * The full memory barrier within wq_has_sleeper() pairs with the full | |
3744 | * memory barrier within set_current_state() of | |
3745 | * prepare_to_wait_event(), which is called after ___wait_event() adds | |
3746 | * the waiter but before it has checked the wait condition. | |
3747 | * | |
5831788a | 3748 | * This pairs with devkmsg_read:A and syslog_print:A. |
1f5d7830 | 3749 | */ |
5341b93d | 3750 | if (wq_has_sleeper(&log_wait) || /* LMM(__wake_up_klogd:A) */ |
5831788a | 3751 | (val & PRINTK_PENDING_OUTPUT)) { |
5341b93d | 3752 | this_cpu_or(printk_pending, val); |
bb964a92 | 3753 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
dc72c32e FW |
3754 | } |
3755 | preempt_enable(); | |
3756 | } | |
717115e1 | 3757 | |
5341b93d | 3758 | void wake_up_klogd(void) |
600e1458 | 3759 | { |
5341b93d JO |
3760 | __wake_up_klogd(PRINTK_PENDING_WAKEUP); |
3761 | } | |
ab6f762f | 3762 | |
5341b93d JO |
3763 | void defer_console_output(void) |
3764 | { | |
3765 | /* | |
3766 | * New messages may have been added directly to the ringbuffer | |
3767 | * using vprintk_store(), so wake any waiters as well. | |
3768 | */ | |
5831788a | 3769 | __wake_up_klogd(PRINTK_PENDING_WAKEUP | PRINTK_PENDING_OUTPUT); |
a338f84d PM |
3770 | } |
3771 | ||
5d5e4522 NP |
3772 | void printk_trigger_flush(void) |
3773 | { | |
3774 | defer_console_output(); | |
3775 | } | |
3776 | ||
a338f84d PM |
3777 | int vprintk_deferred(const char *fmt, va_list args) |
3778 | { | |
3779 | int r; | |
3780 | ||
74caba7f | 3781 | r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, fmt, args); |
a338f84d | 3782 | defer_console_output(); |
600e1458 PZ |
3783 | |
3784 | return r; | |
3785 | } | |
3786 | ||
33701557 | 3787 | int _printk_deferred(const char *fmt, ...) |
719f6a70 PM |
3788 | { |
3789 | va_list args; | |
3790 | int r; | |
3791 | ||
3792 | va_start(args, fmt); | |
3793 | r = vprintk_deferred(fmt, args); | |
3794 | va_end(args); | |
3795 | ||
3796 | return r; | |
3797 | } | |
3798 | ||
1da177e4 LT |
3799 | /* |
3800 | * printk rate limiting, lifted from the networking subsystem. | |
3801 | * | |
641de9d8 UKK |
3802 | * This enforces a rate limit: not more than 10 kernel messages |
3803 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 3804 | */ |
641de9d8 UKK |
3805 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
3806 | ||
5c828713 | 3807 | int __printk_ratelimit(const char *func) |
1da177e4 | 3808 | { |
5c828713 | 3809 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 3810 | } |
5c828713 | 3811 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
3812 | |
3813 | /** | |
3814 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
3815 | * @caller_jiffies: pointer to caller's state | |
3816 | * @interval_msecs: minimum interval between prints | |
3817 | * | |
3818 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
3819 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
3820 | * returned true. | |
3821 | */ | |
3822 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
3823 | unsigned int interval_msecs) | |
3824 | { | |
249771b8 AE |
3825 | unsigned long elapsed = jiffies - *caller_jiffies; |
3826 | ||
3827 | if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) | |
3828 | return false; | |
3829 | ||
3830 | *caller_jiffies = jiffies; | |
3831 | return true; | |
f46c4833 AM |
3832 | } |
3833 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
3834 | |
3835 | static DEFINE_SPINLOCK(dump_list_lock); | |
3836 | static LIST_HEAD(dump_list); | |
3837 | ||
3838 | /** | |
3839 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 3840 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
3841 | * |
3842 | * Adds a kernel log dumper to the system. The dump callback in the | |
3843 | * structure will be called when the kernel oopses or panics and must be | |
3844 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
3845 | */ | |
3846 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
3847 | { | |
3848 | unsigned long flags; | |
3849 | int err = -EBUSY; | |
3850 | ||
3851 | /* The dump callback needs to be set */ | |
3852 | if (!dumper->dump) | |
3853 | return -EINVAL; | |
3854 | ||
3855 | spin_lock_irqsave(&dump_list_lock, flags); | |
3856 | /* Don't allow registering multiple times */ | |
3857 | if (!dumper->registered) { | |
3858 | dumper->registered = 1; | |
fb842b00 | 3859 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
3860 | err = 0; |
3861 | } | |
3862 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
3863 | ||
3864 | return err; | |
3865 | } | |
3866 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
3867 | ||
3868 | /** | |
3869 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 3870 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
3871 | * |
3872 | * Removes a dump device from the system. Returns zero on success and | |
3873 | * %-EINVAL otherwise. | |
3874 | */ | |
3875 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
3876 | { | |
3877 | unsigned long flags; | |
3878 | int err = -EINVAL; | |
3879 | ||
3880 | spin_lock_irqsave(&dump_list_lock, flags); | |
3881 | if (dumper->registered) { | |
3882 | dumper->registered = 0; | |
fb842b00 | 3883 | list_del_rcu(&dumper->list); |
456b565c SK |
3884 | err = 0; |
3885 | } | |
3886 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 3887 | synchronize_rcu(); |
456b565c SK |
3888 | |
3889 | return err; | |
3890 | } | |
3891 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
3892 | ||
7ff9554b KS |
3893 | static bool always_kmsg_dump; |
3894 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); | |
3895 | ||
fb13cb8a KC |
3896 | const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason) |
3897 | { | |
3898 | switch (reason) { | |
3899 | case KMSG_DUMP_PANIC: | |
3900 | return "Panic"; | |
3901 | case KMSG_DUMP_OOPS: | |
3902 | return "Oops"; | |
3903 | case KMSG_DUMP_EMERG: | |
3904 | return "Emergency"; | |
3905 | case KMSG_DUMP_SHUTDOWN: | |
3906 | return "Shutdown"; | |
3907 | default: | |
3908 | return "Unknown"; | |
3909 | } | |
3910 | } | |
3911 | EXPORT_SYMBOL_GPL(kmsg_dump_reason_str); | |
3912 | ||
456b565c SK |
3913 | /** |
3914 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
3915 | * @reason: the reason (oops, panic etc) for dumping | |
3916 | * | |
e2ae715d KS |
3917 | * Call each of the registered dumper's dump() callback, which can |
3918 | * retrieve the kmsg records with kmsg_dump_get_line() or | |
3919 | * kmsg_dump_get_buffer(). | |
456b565c SK |
3920 | */ |
3921 | void kmsg_dump(enum kmsg_dump_reason reason) | |
3922 | { | |
456b565c | 3923 | struct kmsg_dumper *dumper; |
456b565c | 3924 | |
e2ae715d KS |
3925 | rcu_read_lock(); |
3926 | list_for_each_entry_rcu(dumper, &dump_list, list) { | |
b1f6f161 PT |
3927 | enum kmsg_dump_reason max_reason = dumper->max_reason; |
3928 | ||
3929 | /* | |
3930 | * If client has not provided a specific max_reason, default | |
3931 | * to KMSG_DUMP_OOPS, unless always_kmsg_dump was set. | |
3932 | */ | |
3933 | if (max_reason == KMSG_DUMP_UNDEF) { | |
3934 | max_reason = always_kmsg_dump ? KMSG_DUMP_MAX : | |
3935 | KMSG_DUMP_OOPS; | |
3936 | } | |
3937 | if (reason > max_reason) | |
e2ae715d KS |
3938 | continue; |
3939 | ||
e2ae715d KS |
3940 | /* invoke dumper which will iterate over records */ |
3941 | dumper->dump(dumper, reason); | |
e2ae715d KS |
3942 | } |
3943 | rcu_read_unlock(); | |
3944 | } | |
3945 | ||
3946 | /** | |
a4f98765 | 3947 | * kmsg_dump_get_line - retrieve one kmsg log line |
f9f3f02d | 3948 | * @iter: kmsg dump iterator |
e2ae715d KS |
3949 | * @syslog: include the "<4>" prefixes |
3950 | * @line: buffer to copy the line to | |
3951 | * @size: maximum size of the buffer | |
3952 | * @len: length of line placed into buffer | |
3953 | * | |
3954 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
3955 | * record, and copy one record into the provided buffer. | |
3956 | * | |
3957 | * Consecutive calls will return the next available record moving | |
3958 | * towards the end of the buffer with the youngest messages. | |
3959 | * | |
3960 | * A return value of FALSE indicates that there are no more records to | |
3961 | * read. | |
3962 | */ | |
a4f98765 JO |
3963 | bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog, |
3964 | char *line, size_t size, size_t *len) | |
e2ae715d | 3965 | { |
f9f3f02d | 3966 | u64 min_seq = latched_seq_read_nolock(&clear_seq); |
896fbe20 JO |
3967 | struct printk_info info; |
3968 | unsigned int line_count; | |
3969 | struct printk_record r; | |
e2ae715d KS |
3970 | size_t l = 0; |
3971 | bool ret = false; | |
3972 | ||
f9f3f02d JO |
3973 | if (iter->cur_seq < min_seq) |
3974 | iter->cur_seq = min_seq; | |
3975 | ||
f35efc78 | 3976 | prb_rec_init_rd(&r, &info, line, size); |
896fbe20 | 3977 | |
896fbe20 JO |
3978 | /* Read text or count text lines? */ |
3979 | if (line) { | |
f9f3f02d | 3980 | if (!prb_read_valid(prb, iter->cur_seq, &r)) |
896fbe20 JO |
3981 | goto out; |
3982 | l = record_print_text(&r, syslog, printk_time); | |
3983 | } else { | |
f9f3f02d | 3984 | if (!prb_read_valid_info(prb, iter->cur_seq, |
896fbe20 JO |
3985 | &info, &line_count)) { |
3986 | goto out; | |
3987 | } | |
3988 | l = get_record_print_text_size(&info, line_count, syslog, | |
3989 | printk_time); | |
456b565c | 3990 | |
896fbe20 | 3991 | } |
e2ae715d | 3992 | |
f9f3f02d | 3993 | iter->cur_seq = r.info->seq + 1; |
e2ae715d | 3994 | ret = true; |
e2ae715d KS |
3995 | out: |
3996 | if (len) | |
3997 | *len = l; | |
3998 | return ret; | |
3999 | } | |
4000 | EXPORT_SYMBOL_GPL(kmsg_dump_get_line); | |
4001 | ||
4002 | /** | |
4003 | * kmsg_dump_get_buffer - copy kmsg log lines | |
f9f3f02d | 4004 | * @iter: kmsg dump iterator |
e2ae715d | 4005 | * @syslog: include the "<4>" prefixes |
4f0f4af5 | 4006 | * @buf: buffer to copy the line to |
e2ae715d | 4007 | * @size: maximum size of the buffer |
726b5097 | 4008 | * @len_out: length of line placed into buffer |
e2ae715d KS |
4009 | * |
4010 | * Start at the end of the kmsg buffer and fill the provided buffer | |
547bbf7d | 4011 | * with as many of the *youngest* kmsg records that fit into it. |
e2ae715d KS |
4012 | * If the buffer is large enough, all available kmsg records will be |
4013 | * copied with a single call. | |
4014 | * | |
4015 | * Consecutive calls will fill the buffer with the next block of | |
4016 | * available older records, not including the earlier retrieved ones. | |
4017 | * | |
4018 | * A return value of FALSE indicates that there are no more records to | |
4019 | * read. | |
4020 | */ | |
f9f3f02d | 4021 | bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog, |
726b5097 | 4022 | char *buf, size_t size, size_t *len_out) |
e2ae715d | 4023 | { |
f9f3f02d | 4024 | u64 min_seq = latched_seq_read_nolock(&clear_seq); |
896fbe20 | 4025 | struct printk_info info; |
896fbe20 | 4026 | struct printk_record r; |
e2ae715d | 4027 | u64 seq; |
e2ae715d | 4028 | u64 next_seq; |
726b5097 | 4029 | size_t len = 0; |
e2ae715d | 4030 | bool ret = false; |
e80c1a9d | 4031 | bool time = printk_time; |
e2ae715d | 4032 | |
5f6c7648 | 4033 | if (!buf || !size) |
e2ae715d KS |
4034 | goto out; |
4035 | ||
f9f3f02d JO |
4036 | if (iter->cur_seq < min_seq) |
4037 | iter->cur_seq = min_seq; | |
4038 | ||
f9f3f02d JO |
4039 | if (prb_read_valid_info(prb, iter->cur_seq, &info, NULL)) { |
4040 | if (info.seq != iter->cur_seq) { | |
13791c80 | 4041 | /* messages are gone, move to first available one */ |
f9f3f02d | 4042 | iter->cur_seq = info.seq; |
13791c80 | 4043 | } |
e2ae715d KS |
4044 | } |
4045 | ||
4046 | /* last entry */ | |
93d102f0 | 4047 | if (iter->cur_seq >= iter->next_seq) |
e2ae715d | 4048 | goto out; |
e2ae715d | 4049 | |
726b5097 JO |
4050 | /* |
4051 | * Find first record that fits, including all following records, | |
4260e0e5 JO |
4052 | * into the user-provided buffer for this dump. Pass in size-1 |
4053 | * because this function (by way of record_print_text()) will | |
4054 | * not write more than size-1 bytes of text into @buf. | |
726b5097 | 4055 | */ |
f9f3f02d | 4056 | seq = find_first_fitting_seq(iter->cur_seq, iter->next_seq, |
4260e0e5 | 4057 | size - 1, syslog, time); |
e2ae715d | 4058 | |
726b5097 JO |
4059 | /* |
4060 | * Next kmsg_dump_get_buffer() invocation will dump block of | |
4061 | * older records stored right before this one. | |
4062 | */ | |
e2ae715d | 4063 | next_seq = seq; |
e2ae715d | 4064 | |
726b5097 JO |
4065 | prb_rec_init_rd(&r, &info, buf, size); |
4066 | ||
4067 | len = 0; | |
4068 | prb_for_each_record(seq, prb, seq, &r) { | |
f9f3f02d | 4069 | if (r.info->seq >= iter->next_seq) |
896fbe20 JO |
4070 | break; |
4071 | ||
726b5097 | 4072 | len += record_print_text(&r, syslog, time); |
896fbe20 | 4073 | |
726b5097 JO |
4074 | /* Adjust record to store to remaining buffer space. */ |
4075 | prb_rec_init_rd(&r, &info, buf + len, size - len); | |
e2ae715d KS |
4076 | } |
4077 | ||
f9f3f02d | 4078 | iter->next_seq = next_seq; |
e2ae715d | 4079 | ret = true; |
e2ae715d | 4080 | out: |
726b5097 JO |
4081 | if (len_out) |
4082 | *len_out = len; | |
e2ae715d KS |
4083 | return ret; |
4084 | } | |
4085 | EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); | |
456b565c | 4086 | |
e2ae715d | 4087 | /** |
325606af | 4088 | * kmsg_dump_rewind - reset the iterator |
f9f3f02d | 4089 | * @iter: kmsg dump iterator |
e2ae715d KS |
4090 | * |
4091 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
4092 | * kmsg_dump_get_buffer() can be called again and used multiple | |
4093 | * times within the same dumper.dump() callback. | |
4094 | */ | |
f9f3f02d | 4095 | void kmsg_dump_rewind(struct kmsg_dump_iter *iter) |
e2ae715d | 4096 | { |
a4f98765 JO |
4097 | iter->cur_seq = latched_seq_read_nolock(&clear_seq); |
4098 | iter->next_seq = prb_next_seq(prb); | |
456b565c | 4099 | } |
e2ae715d | 4100 | EXPORT_SYMBOL_GPL(kmsg_dump_rewind); |
196779b9 | 4101 | |
7ef3d2fd | 4102 | #endif |
766c268b JO |
4103 | |
4104 | #ifdef CONFIG_SMP | |
faebd693 JO |
4105 | static atomic_t printk_cpu_sync_owner = ATOMIC_INIT(-1); |
4106 | static atomic_t printk_cpu_sync_nested = ATOMIC_INIT(0); | |
766c268b JO |
4107 | |
4108 | /** | |
faebd693 JO |
4109 | * __printk_cpu_sync_wait() - Busy wait until the printk cpu-reentrant |
4110 | * spinning lock is not owned by any CPU. | |
766c268b JO |
4111 | * |
4112 | * Context: Any context. | |
4113 | */ | |
faebd693 | 4114 | void __printk_cpu_sync_wait(void) |
766c268b JO |
4115 | { |
4116 | do { | |
4117 | cpu_relax(); | |
faebd693 | 4118 | } while (atomic_read(&printk_cpu_sync_owner) != -1); |
766c268b | 4119 | } |
faebd693 | 4120 | EXPORT_SYMBOL(__printk_cpu_sync_wait); |
766c268b JO |
4121 | |
4122 | /** | |
faebd693 JO |
4123 | * __printk_cpu_sync_try_get() - Try to acquire the printk cpu-reentrant |
4124 | * spinning lock. | |
766c268b JO |
4125 | * |
4126 | * If no processor has the lock, the calling processor takes the lock and | |
4127 | * becomes the owner. If the calling processor is already the owner of the | |
4128 | * lock, this function succeeds immediately. | |
4129 | * | |
4130 | * Context: Any context. Expects interrupts to be disabled. | |
4131 | * Return: 1 on success, otherwise 0. | |
4132 | */ | |
faebd693 | 4133 | int __printk_cpu_sync_try_get(void) |
766c268b JO |
4134 | { |
4135 | int cpu; | |
4136 | int old; | |
4137 | ||
4138 | cpu = smp_processor_id(); | |
4139 | ||
3342aa8e JO |
4140 | /* |
4141 | * Guarantee loads and stores from this CPU when it is the lock owner | |
4142 | * are _not_ visible to the previous lock owner. This pairs with | |
faebd693 | 4143 | * __printk_cpu_sync_put:B. |
3342aa8e JO |
4144 | * |
4145 | * Memory barrier involvement: | |
4146 | * | |
faebd693 JO |
4147 | * If __printk_cpu_sync_try_get:A reads from __printk_cpu_sync_put:B, |
4148 | * then __printk_cpu_sync_put:A can never read from | |
4149 | * __printk_cpu_sync_try_get:B. | |
3342aa8e JO |
4150 | * |
4151 | * Relies on: | |
4152 | * | |
faebd693 | 4153 | * RELEASE from __printk_cpu_sync_put:A to __printk_cpu_sync_put:B |
3342aa8e JO |
4154 | * of the previous CPU |
4155 | * matching | |
faebd693 JO |
4156 | * ACQUIRE from __printk_cpu_sync_try_get:A to |
4157 | * __printk_cpu_sync_try_get:B of this CPU | |
3342aa8e | 4158 | */ |
faebd693 JO |
4159 | old = atomic_cmpxchg_acquire(&printk_cpu_sync_owner, -1, |
4160 | cpu); /* LMM(__printk_cpu_sync_try_get:A) */ | |
766c268b | 4161 | if (old == -1) { |
3342aa8e JO |
4162 | /* |
4163 | * This CPU is now the owner and begins loading/storing | |
faebd693 | 4164 | * data: LMM(__printk_cpu_sync_try_get:B) |
3342aa8e | 4165 | */ |
766c268b | 4166 | return 1; |
3342aa8e | 4167 | |
766c268b JO |
4168 | } else if (old == cpu) { |
4169 | /* This CPU is already the owner. */ | |
faebd693 | 4170 | atomic_inc(&printk_cpu_sync_nested); |
766c268b JO |
4171 | return 1; |
4172 | } | |
4173 | ||
4174 | return 0; | |
4175 | } | |
faebd693 | 4176 | EXPORT_SYMBOL(__printk_cpu_sync_try_get); |
766c268b JO |
4177 | |
4178 | /** | |
faebd693 | 4179 | * __printk_cpu_sync_put() - Release the printk cpu-reentrant spinning lock. |
766c268b JO |
4180 | * |
4181 | * The calling processor must be the owner of the lock. | |
4182 | * | |
4183 | * Context: Any context. Expects interrupts to be disabled. | |
4184 | */ | |
faebd693 | 4185 | void __printk_cpu_sync_put(void) |
766c268b | 4186 | { |
faebd693 JO |
4187 | if (atomic_read(&printk_cpu_sync_nested)) { |
4188 | atomic_dec(&printk_cpu_sync_nested); | |
766c268b JO |
4189 | return; |
4190 | } | |
4191 | ||
3342aa8e JO |
4192 | /* |
4193 | * This CPU is finished loading/storing data: | |
faebd693 | 4194 | * LMM(__printk_cpu_sync_put:A) |
3342aa8e JO |
4195 | */ |
4196 | ||
4197 | /* | |
4198 | * Guarantee loads and stores from this CPU when it was the | |
4199 | * lock owner are visible to the next lock owner. This pairs | |
faebd693 | 4200 | * with __printk_cpu_sync_try_get:A. |
3342aa8e JO |
4201 | * |
4202 | * Memory barrier involvement: | |
4203 | * | |
faebd693 JO |
4204 | * If __printk_cpu_sync_try_get:A reads from __printk_cpu_sync_put:B, |
4205 | * then __printk_cpu_sync_try_get:B reads from __printk_cpu_sync_put:A. | |
3342aa8e JO |
4206 | * |
4207 | * Relies on: | |
4208 | * | |
faebd693 | 4209 | * RELEASE from __printk_cpu_sync_put:A to __printk_cpu_sync_put:B |
3342aa8e JO |
4210 | * of this CPU |
4211 | * matching | |
faebd693 JO |
4212 | * ACQUIRE from __printk_cpu_sync_try_get:A to |
4213 | * __printk_cpu_sync_try_get:B of the next CPU | |
3342aa8e | 4214 | */ |
faebd693 JO |
4215 | atomic_set_release(&printk_cpu_sync_owner, |
4216 | -1); /* LMM(__printk_cpu_sync_put:B) */ | |
766c268b | 4217 | } |
faebd693 | 4218 | EXPORT_SYMBOL(__printk_cpu_sync_put); |
766c268b | 4219 | #endif /* CONFIG_SMP */ |