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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * linux/kernel/printk.c | |
4 | * | |
5 | * Copyright (C) 1991, 1992 Linus Torvalds | |
6 | * | |
7 | * Modified to make sys_syslog() more flexible: added commands to | |
8 | * return the last 4k of kernel messages, regardless of whether | |
9 | * they've been read or not. Added option to suppress kernel printk's | |
10 | * to the console. Added hook for sending the console messages | |
11 | * elsewhere, in preparation for a serial line console (someday). | |
12 | * Ted Ts'o, 2/11/93. | |
13 | * Modified for sysctl support, 1/8/97, Chris Horn. | |
40dc5651 | 14 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 15 | * manfred@colorfullife.com |
1da177e4 | 16 | * Rewrote bits to get rid of console_lock |
e1f8e874 | 17 | * 01Mar01 Andrew Morton |
1da177e4 LT |
18 | */ |
19 | ||
dd5adbfb HZ |
20 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
21 | ||
1da177e4 LT |
22 | #include <linux/kernel.h> |
23 | #include <linux/mm.h> | |
24 | #include <linux/tty.h> | |
25 | #include <linux/tty_driver.h> | |
1da177e4 LT |
26 | #include <linux/console.h> |
27 | #include <linux/init.h> | |
bfe8df3d RD |
28 | #include <linux/jiffies.h> |
29 | #include <linux/nmi.h> | |
1da177e4 | 30 | #include <linux/module.h> |
3b9c0410 | 31 | #include <linux/moduleparam.h> |
1da177e4 LT |
32 | #include <linux/delay.h> |
33 | #include <linux/smp.h> | |
34 | #include <linux/security.h> | |
162a7e75 | 35 | #include <linux/memblock.h> |
1da177e4 | 36 | #include <linux/syscalls.h> |
692f66f2 | 37 | #include <linux/crash_core.h> |
3fff4c42 | 38 | #include <linux/ratelimit.h> |
456b565c | 39 | #include <linux/kmsg_dump.h> |
00234592 | 40 | #include <linux/syslog.h> |
034260d6 | 41 | #include <linux/cpu.h> |
fb842b00 | 42 | #include <linux/rculist.h> |
e11fea92 | 43 | #include <linux/poll.h> |
74876a98 | 44 | #include <linux/irq_work.h> |
249771b8 | 45 | #include <linux/ctype.h> |
e2e40f2c | 46 | #include <linux/uio.h> |
e6017571 | 47 | #include <linux/sched/clock.h> |
b17b0153 | 48 | #include <linux/sched/debug.h> |
68db0cf1 | 49 | #include <linux/sched/task_stack.h> |
1da177e4 | 50 | |
7c0f6ba6 | 51 | #include <linux/uaccess.h> |
40a7d9f5 | 52 | #include <asm/sections.h> |
1da177e4 | 53 | |
58eacfff | 54 | #include <trace/events/initcall.h> |
95100358 JB |
55 | #define CREATE_TRACE_POINTS |
56 | #include <trace/events/printk.h> | |
57 | ||
896fbe20 | 58 | #include "printk_ringbuffer.h" |
d197c43d | 59 | #include "console_cmdline.h" |
bbeddf52 | 60 | #include "braille.h" |
42a0bb3f | 61 | #include "internal.h" |
d197c43d | 62 | |
1da177e4 | 63 | int console_printk[4] = { |
a8fe19eb | 64 | CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */ |
42a9dc0b | 65 | MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */ |
a8fe19eb BP |
66 | CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */ |
67 | CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ | |
1da177e4 | 68 | }; |
a1939185 | 69 | EXPORT_SYMBOL_GPL(console_printk); |
1da177e4 | 70 | |
56e6c104 TZ |
71 | atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0); |
72 | EXPORT_SYMBOL(ignore_console_lock_warning); | |
73 | ||
1da177e4 | 74 | /* |
0bbfb7c2 | 75 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
76 | * their unblank() callback or not. So let's export it. |
77 | */ | |
78 | int oops_in_progress; | |
79 | EXPORT_SYMBOL(oops_in_progress); | |
80 | ||
81 | /* | |
82 | * console_sem protects the console_drivers list, and also | |
83 | * provides serialisation for access to the entire console | |
84 | * driver system. | |
85 | */ | |
5b8c4f23 | 86 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 87 | struct console *console_drivers; |
a29d1cfe IM |
88 | EXPORT_SYMBOL_GPL(console_drivers); |
89 | ||
c39ea0b9 FT |
90 | /* |
91 | * System may need to suppress printk message under certain | |
92 | * circumstances, like after kernel panic happens. | |
93 | */ | |
94 | int __read_mostly suppress_printk; | |
95 | ||
13fb0f74 SB |
96 | /* |
97 | * During panic, heavy printk by other CPUs can delay the | |
98 | * panic and risk deadlock on console resources. | |
99 | */ | |
ce06e863 | 100 | static int __read_mostly suppress_panic_printk; |
13fb0f74 | 101 | |
daee7797 DV |
102 | #ifdef CONFIG_LOCKDEP |
103 | static struct lockdep_map console_lock_dep_map = { | |
104 | .name = "console_lock" | |
105 | }; | |
106 | #endif | |
107 | ||
750afe7b BP |
108 | enum devkmsg_log_bits { |
109 | __DEVKMSG_LOG_BIT_ON = 0, | |
110 | __DEVKMSG_LOG_BIT_OFF, | |
111 | __DEVKMSG_LOG_BIT_LOCK, | |
112 | }; | |
113 | ||
114 | enum devkmsg_log_masks { | |
115 | DEVKMSG_LOG_MASK_ON = BIT(__DEVKMSG_LOG_BIT_ON), | |
116 | DEVKMSG_LOG_MASK_OFF = BIT(__DEVKMSG_LOG_BIT_OFF), | |
117 | DEVKMSG_LOG_MASK_LOCK = BIT(__DEVKMSG_LOG_BIT_LOCK), | |
118 | }; | |
119 | ||
120 | /* Keep both the 'on' and 'off' bits clear, i.e. ratelimit by default: */ | |
121 | #define DEVKMSG_LOG_MASK_DEFAULT 0 | |
122 | ||
123 | static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; | |
124 | ||
125 | static int __control_devkmsg(char *str) | |
126 | { | |
35c35493 CY |
127 | size_t len; |
128 | ||
750afe7b BP |
129 | if (!str) |
130 | return -EINVAL; | |
131 | ||
35c35493 CY |
132 | len = str_has_prefix(str, "on"); |
133 | if (len) { | |
750afe7b | 134 | devkmsg_log = DEVKMSG_LOG_MASK_ON; |
35c35493 CY |
135 | return len; |
136 | } | |
137 | ||
138 | len = str_has_prefix(str, "off"); | |
139 | if (len) { | |
750afe7b | 140 | devkmsg_log = DEVKMSG_LOG_MASK_OFF; |
35c35493 CY |
141 | return len; |
142 | } | |
143 | ||
144 | len = str_has_prefix(str, "ratelimit"); | |
145 | if (len) { | |
750afe7b | 146 | devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; |
35c35493 | 147 | return len; |
750afe7b | 148 | } |
35c35493 | 149 | |
750afe7b BP |
150 | return -EINVAL; |
151 | } | |
152 | ||
153 | static int __init control_devkmsg(char *str) | |
154 | { | |
b665eae7 RD |
155 | if (__control_devkmsg(str) < 0) { |
156 | pr_warn("printk.devkmsg: bad option string '%s'\n", str); | |
750afe7b | 157 | return 1; |
b665eae7 | 158 | } |
750afe7b BP |
159 | |
160 | /* | |
161 | * Set sysctl string accordingly: | |
162 | */ | |
6fd78a1a SS |
163 | if (devkmsg_log == DEVKMSG_LOG_MASK_ON) |
164 | strcpy(devkmsg_log_str, "on"); | |
165 | else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF) | |
166 | strcpy(devkmsg_log_str, "off"); | |
750afe7b BP |
167 | /* else "ratelimit" which is set by default. */ |
168 | ||
169 | /* | |
170 | * Sysctl cannot change it anymore. The kernel command line setting of | |
171 | * this parameter is to force the setting to be permanent throughout the | |
172 | * runtime of the system. This is a precation measure against userspace | |
173 | * trying to be a smarta** and attempting to change it up on us. | |
174 | */ | |
175 | devkmsg_log |= DEVKMSG_LOG_MASK_LOCK; | |
176 | ||
b665eae7 | 177 | return 1; |
750afe7b BP |
178 | } |
179 | __setup("printk.devkmsg=", control_devkmsg); | |
180 | ||
181 | char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit"; | |
fdcd4073 | 182 | #if defined(CONFIG_PRINTK) && defined(CONFIG_SYSCTL) |
750afe7b | 183 | int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, |
32927393 | 184 | void *buffer, size_t *lenp, loff_t *ppos) |
750afe7b BP |
185 | { |
186 | char old_str[DEVKMSG_STR_MAX_SIZE]; | |
187 | unsigned int old; | |
188 | int err; | |
189 | ||
190 | if (write) { | |
191 | if (devkmsg_log & DEVKMSG_LOG_MASK_LOCK) | |
192 | return -EINVAL; | |
193 | ||
194 | old = devkmsg_log; | |
195 | strncpy(old_str, devkmsg_log_str, DEVKMSG_STR_MAX_SIZE); | |
196 | } | |
197 | ||
198 | err = proc_dostring(table, write, buffer, lenp, ppos); | |
199 | if (err) | |
200 | return err; | |
201 | ||
202 | if (write) { | |
203 | err = __control_devkmsg(devkmsg_log_str); | |
204 | ||
205 | /* | |
206 | * Do not accept an unknown string OR a known string with | |
207 | * trailing crap... | |
208 | */ | |
209 | if (err < 0 || (err + 1 != *lenp)) { | |
210 | ||
211 | /* ... and restore old setting. */ | |
212 | devkmsg_log = old; | |
213 | strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE); | |
214 | ||
215 | return -EINVAL; | |
216 | } | |
217 | } | |
218 | ||
219 | return 0; | |
220 | } | |
fdcd4073 | 221 | #endif /* CONFIG_PRINTK && CONFIG_SYSCTL */ |
750afe7b | 222 | |
9627808d | 223 | /* Number of registered extended console drivers. */ |
6fe29354 TH |
224 | static int nr_ext_console_drivers; |
225 | ||
8e274732 JO |
226 | /* |
227 | * Used to synchronize printing kthreads against direct printing via | |
228 | * console_trylock/console_unlock. | |
229 | * | |
230 | * Values: | |
231 | * -1 = console kthreads atomically blocked (via global trylock) | |
232 | * 0 = no kthread printing, console not locked (via trylock) | |
233 | * >0 = kthread(s) actively printing | |
234 | * | |
235 | * Note: For synchronizing against direct printing via | |
236 | * console_lock/console_unlock, see the @lock variable in | |
237 | * struct console. | |
238 | */ | |
239 | static atomic_t console_kthreads_active = ATOMIC_INIT(0); | |
240 | ||
241 | #define console_kthreads_atomic_tryblock() \ | |
242 | (atomic_cmpxchg(&console_kthreads_active, 0, -1) == 0) | |
243 | #define console_kthreads_atomic_unblock() \ | |
244 | atomic_cmpxchg(&console_kthreads_active, -1, 0) | |
245 | #define console_kthreads_atomically_blocked() \ | |
246 | (atomic_read(&console_kthreads_active) == -1) | |
247 | ||
248 | #define console_kthread_printing_tryenter() \ | |
249 | atomic_inc_unless_negative(&console_kthreads_active) | |
250 | #define console_kthread_printing_exit() \ | |
251 | atomic_dec(&console_kthreads_active) | |
252 | ||
bd8d7cf5 JK |
253 | /* |
254 | * Helper macros to handle lockdep when locking/unlocking console_sem. We use | |
255 | * macros instead of functions so that _RET_IP_ contains useful information. | |
256 | */ | |
257 | #define down_console_sem() do { \ | |
258 | down(&console_sem);\ | |
259 | mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ | |
260 | } while (0) | |
261 | ||
262 | static int __down_trylock_console_sem(unsigned long ip) | |
263 | { | |
f975237b SS |
264 | int lock_failed; |
265 | unsigned long flags; | |
266 | ||
267 | /* | |
268 | * Here and in __up_console_sem() we need to be in safe mode, | |
269 | * because spindump/WARN/etc from under console ->lock will | |
270 | * deadlock in printk()->down_trylock_console_sem() otherwise. | |
271 | */ | |
272 | printk_safe_enter_irqsave(flags); | |
273 | lock_failed = down_trylock(&console_sem); | |
274 | printk_safe_exit_irqrestore(flags); | |
275 | ||
276 | if (lock_failed) | |
bd8d7cf5 JK |
277 | return 1; |
278 | mutex_acquire(&console_lock_dep_map, 0, 1, ip); | |
279 | return 0; | |
280 | } | |
281 | #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) | |
282 | ||
f975237b SS |
283 | static void __up_console_sem(unsigned long ip) |
284 | { | |
285 | unsigned long flags; | |
286 | ||
5facae4f | 287 | mutex_release(&console_lock_dep_map, ip); |
f975237b SS |
288 | |
289 | printk_safe_enter_irqsave(flags); | |
290 | up(&console_sem); | |
291 | printk_safe_exit_irqrestore(flags); | |
292 | } | |
293 | #define up_console_sem() __up_console_sem(_RET_IP_) | |
bd8d7cf5 | 294 | |
77498617 SB |
295 | static bool panic_in_progress(void) |
296 | { | |
297 | return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID); | |
298 | } | |
299 | ||
8e274732 JO |
300 | /* |
301 | * Tracks whether kthread printers are all blocked. A value of true implies | |
302 | * that the console is locked via console_lock() or the console is suspended. | |
303 | * Writing to this variable requires holding @console_sem. | |
304 | */ | |
305 | static bool console_kthreads_blocked; | |
306 | ||
307 | /* | |
308 | * Block all kthread printers from a schedulable context. | |
309 | * | |
310 | * Requires holding @console_sem. | |
311 | */ | |
312 | static void console_kthreads_block(void) | |
313 | { | |
314 | struct console *con; | |
315 | ||
316 | for_each_console(con) { | |
317 | mutex_lock(&con->lock); | |
318 | con->blocked = true; | |
319 | mutex_unlock(&con->lock); | |
320 | } | |
321 | ||
322 | console_kthreads_blocked = true; | |
323 | } | |
324 | ||
325 | /* | |
326 | * Unblock all kthread printers from a schedulable context. | |
327 | * | |
328 | * Requires holding @console_sem. | |
329 | */ | |
330 | static void console_kthreads_unblock(void) | |
331 | { | |
332 | struct console *con; | |
333 | ||
334 | for_each_console(con) { | |
335 | mutex_lock(&con->lock); | |
336 | con->blocked = false; | |
337 | mutex_unlock(&con->lock); | |
338 | } | |
339 | ||
340 | console_kthreads_blocked = false; | |
341 | } | |
342 | ||
ab406816 | 343 | static int console_suspended; |
1da177e4 | 344 | |
1da177e4 LT |
345 | /* |
346 | * Array of consoles built from command line options (console=) | |
347 | */ | |
1da177e4 LT |
348 | |
349 | #define MAX_CMDLINECONSOLES 8 | |
350 | ||
351 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
d197c43d | 352 | |
1da177e4 | 353 | static int preferred_console = -1; |
9e124fe1 MA |
354 | int console_set_on_cmdline; |
355 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
356 | |
357 | /* Flag: console code may call schedule() */ | |
358 | static int console_may_schedule; | |
359 | ||
cca10d58 SS |
360 | enum con_msg_format_flags { |
361 | MSG_FORMAT_DEFAULT = 0, | |
362 | MSG_FORMAT_SYSLOG = (1 << 0), | |
363 | }; | |
364 | ||
365 | static int console_msg_format = MSG_FORMAT_DEFAULT; | |
366 | ||
7ff9554b | 367 | /* |
896fbe20 | 368 | * The printk log buffer consists of a sequenced collection of records, each |
74caba7f JO |
369 | * containing variable length message text. Every record also contains its |
370 | * own meta-data (@info). | |
7ff9554b | 371 | * |
896fbe20 JO |
372 | * Every record meta-data carries the timestamp in microseconds, as well as |
373 | * the standard userspace syslog level and syslog facility. The usual kernel | |
374 | * messages use LOG_KERN; userspace-injected messages always carry a matching | |
375 | * syslog facility, by default LOG_USER. The origin of every message can be | |
376 | * reliably determined that way. | |
7ff9554b | 377 | * |
896fbe20 JO |
378 | * The human readable log message of a record is available in @text, the |
379 | * length of the message text in @text_len. The stored message is not | |
380 | * terminated. | |
7ff9554b | 381 | * |
896fbe20 | 382 | * Optionally, a record can carry a dictionary of properties (key/value |
74caba7f | 383 | * pairs), to provide userspace with a machine-readable message context. |
e11fea92 KS |
384 | * |
385 | * Examples for well-defined, commonly used property names are: | |
386 | * DEVICE=b12:8 device identifier | |
387 | * b12:8 block dev_t | |
388 | * c127:3 char dev_t | |
389 | * n8 netdev ifindex | |
390 | * +sound:card0 subsystem:devname | |
391 | * SUBSYSTEM=pci driver-core subsystem name | |
392 | * | |
74caba7f JO |
393 | * Valid characters in property names are [a-zA-Z0-9.-_]. Property names |
394 | * and values are terminated by a '\0' character. | |
e11fea92 | 395 | * |
896fbe20 | 396 | * Example of record values: |
74caba7f JO |
397 | * record.text_buf = "it's a line" (unterminated) |
398 | * record.info.seq = 56 | |
399 | * record.info.ts_nsec = 36863 | |
400 | * record.info.text_len = 11 | |
401 | * record.info.facility = 0 (LOG_KERN) | |
402 | * record.info.flags = 0 | |
403 | * record.info.level = 3 (LOG_ERR) | |
404 | * record.info.caller_id = 299 (task 299) | |
405 | * record.info.dev_info.subsystem = "pci" (terminated) | |
406 | * record.info.dev_info.device = "+pci:0000:00:01.0" (terminated) | |
896fbe20 JO |
407 | * |
408 | * The 'struct printk_info' buffer must never be directly exported to | |
e11fea92 KS |
409 | * userspace, it is a kernel-private implementation detail that might |
410 | * need to be changed in the future, when the requirements change. | |
411 | * | |
412 | * /dev/kmsg exports the structured data in the following line format: | |
b389645f AO |
413 | * "<level>,<sequnum>,<timestamp>,<contflag>[,additional_values, ... ];<message text>\n" |
414 | * | |
415 | * Users of the export format should ignore possible additional values | |
416 | * separated by ',', and find the message after the ';' character. | |
e11fea92 KS |
417 | * |
418 | * The optional key/value pairs are attached as continuation lines starting | |
419 | * with a space character and terminated by a newline. All possible | |
420 | * non-prinatable characters are escaped in the "\xff" notation. | |
7ff9554b KS |
421 | */ |
422 | ||
636babdc | 423 | /* syslog_lock protects syslog_* variables and write access to clear_seq. */ |
b371cbb5 | 424 | static DEFINE_MUTEX(syslog_lock); |
636babdc | 425 | |
09c5ba0a JO |
426 | /* |
427 | * A flag to signify if printk_activate_kthreads() has already started the | |
428 | * kthread printers. If true, any later registered consoles must start their | |
429 | * own kthread directly. The flag is write protected by the console_lock. | |
430 | */ | |
431 | static bool printk_kthreads_available; | |
432 | ||
96efedf1 | 433 | #ifdef CONFIG_PRINTK |
2bb2b7b5 JO |
434 | static atomic_t printk_prefer_direct = ATOMIC_INIT(0); |
435 | ||
436 | /** | |
437 | * printk_prefer_direct_enter - cause printk() calls to attempt direct | |
438 | * printing to all enabled consoles | |
439 | * | |
440 | * Since it is not possible to call into the console printing code from any | |
441 | * context, there is no guarantee that direct printing will occur. | |
442 | * | |
443 | * This globally effects all printk() callers. | |
444 | * | |
445 | * Context: Any context. | |
446 | */ | |
447 | void printk_prefer_direct_enter(void) | |
448 | { | |
449 | atomic_inc(&printk_prefer_direct); | |
450 | } | |
451 | ||
452 | /** | |
453 | * printk_prefer_direct_exit - restore printk() behavior | |
454 | * | |
455 | * Context: Any context. | |
456 | */ | |
457 | void printk_prefer_direct_exit(void) | |
458 | { | |
459 | WARN_ON(atomic_dec_if_positive(&printk_prefer_direct) < 0); | |
460 | } | |
461 | ||
09c5ba0a JO |
462 | /* |
463 | * Calling printk() always wakes kthread printers so that they can | |
464 | * flush the new message to their respective consoles. Also, if direct | |
465 | * printing is allowed, printk() tries to flush the messages directly. | |
466 | * | |
467 | * Direct printing is allowed in situations when the kthreads | |
468 | * are not available or the system is in a problematic state. | |
469 | * | |
470 | * See the implementation about possible races. | |
471 | */ | |
472 | static inline bool allow_direct_printing(void) | |
473 | { | |
474 | /* | |
475 | * Checking kthread availability is a possible race because the | |
476 | * kthread printers can become permanently disabled during runtime. | |
477 | * However, doing that requires holding the console_lock, so any | |
478 | * pending messages will be direct printed by console_unlock(). | |
479 | */ | |
480 | if (!printk_kthreads_available) | |
481 | return true; | |
482 | ||
483 | /* | |
484 | * Prefer direct printing when the system is in a problematic state. | |
485 | * The context that sets this state will always see the updated value. | |
486 | * The other contexts do not care. Anyway, direct printing is just a | |
487 | * best effort. The direct output is only possible when console_lock | |
488 | * is not already taken and no kthread printers are actively printing. | |
489 | */ | |
490 | return (system_state > SYSTEM_RUNNING || | |
491 | oops_in_progress || | |
492 | atomic_read(&printk_prefer_direct)); | |
493 | } | |
494 | ||
dc72c32e | 495 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
636babdc | 496 | /* All 3 protected by @syslog_lock. */ |
7f3a781d KS |
497 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
498 | static u64 syslog_seq; | |
eb02dac9 | 499 | static size_t syslog_partial; |
e80c1a9d | 500 | static bool syslog_time; |
7ff9554b | 501 | |
7d7a23a9 JO |
502 | struct latched_seq { |
503 | seqcount_latch_t latch; | |
504 | u64 val[2]; | |
505 | }; | |
506 | ||
507 | /* | |
508 | * The next printk record to read after the last 'clear' command. There are | |
509 | * two copies (updated with seqcount_latch) so that reads can locklessly | |
636babdc | 510 | * access a valid value. Writers are synchronized by @syslog_lock. |
7d7a23a9 JO |
511 | */ |
512 | static struct latched_seq clear_seq = { | |
513 | .latch = SEQCNT_LATCH_ZERO(clear_seq.latch), | |
514 | .val[0] = 0, | |
515 | .val[1] = 0, | |
516 | }; | |
7ff9554b | 517 | |
15ff2069 TH |
518 | #ifdef CONFIG_PRINTK_CALLER |
519 | #define PREFIX_MAX 48 | |
520 | #else | |
70498253 | 521 | #define PREFIX_MAX 32 |
15ff2069 | 522 | #endif |
cf5b0208 JO |
523 | |
524 | /* the maximum size of a formatted record (i.e. with prefix added per line) */ | |
525 | #define CONSOLE_LOG_MAX 1024 | |
526 | ||
03a749e6 JO |
527 | /* the maximum size for a dropped text message */ |
528 | #define DROPPED_TEXT_MAX 64 | |
529 | ||
cf5b0208 JO |
530 | /* the maximum size allowed to be reserved for a record */ |
531 | #define LOG_LINE_MAX (CONSOLE_LOG_MAX - PREFIX_MAX) | |
7f3a781d | 532 | |
3824657c MK |
533 | #define LOG_LEVEL(v) ((v) & 0x07) |
534 | #define LOG_FACILITY(v) ((v) >> 3 & 0xff) | |
535 | ||
7f3a781d | 536 | /* record buffer */ |
896fbe20 | 537 | #define LOG_ALIGN __alignof__(unsigned long) |
7f3a781d | 538 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
e6fe3e5b | 539 | #define LOG_BUF_LEN_MAX (u32)(1 << 31) |
f8450fca | 540 | static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); |
7f3a781d KS |
541 | static char *log_buf = __log_buf; |
542 | static u32 log_buf_len = __LOG_BUF_LEN; | |
543 | ||
896fbe20 JO |
544 | /* |
545 | * Define the average message size. This only affects the number of | |
546 | * descriptors that will be available. Underestimating is better than | |
547 | * overestimating (too many available descriptors is better than not enough). | |
896fbe20 JO |
548 | */ |
549 | #define PRB_AVGBITS 5 /* 32 character average length */ | |
550 | ||
551 | #if CONFIG_LOG_BUF_SHIFT <= PRB_AVGBITS | |
552 | #error CONFIG_LOG_BUF_SHIFT value too small. | |
553 | #endif | |
554 | _DEFINE_PRINTKRB(printk_rb_static, CONFIG_LOG_BUF_SHIFT - PRB_AVGBITS, | |
f35efc78 | 555 | PRB_AVGBITS, &__log_buf[0]); |
896fbe20 JO |
556 | |
557 | static struct printk_ringbuffer printk_rb_dynamic; | |
558 | ||
559 | static struct printk_ringbuffer *prb = &printk_rb_static; | |
560 | ||
ab6f762f SS |
561 | /* |
562 | * We cannot access per-CPU data (e.g. per-CPU flush irq_work) before | |
563 | * per_cpu_areas are initialised. This variable is set to true when | |
564 | * it's safe to access per-CPU data. | |
565 | */ | |
566 | static bool __printk_percpu_data_ready __read_mostly; | |
567 | ||
568 | bool printk_percpu_data_ready(void) | |
569 | { | |
570 | return __printk_percpu_data_ready; | |
571 | } | |
572 | ||
636babdc | 573 | /* Must be called under syslog_lock. */ |
7d7a23a9 JO |
574 | static void latched_seq_write(struct latched_seq *ls, u64 val) |
575 | { | |
576 | raw_write_seqcount_latch(&ls->latch); | |
577 | ls->val[0] = val; | |
578 | raw_write_seqcount_latch(&ls->latch); | |
579 | ls->val[1] = val; | |
580 | } | |
581 | ||
582 | /* Can be called from any context. */ | |
583 | static u64 latched_seq_read_nolock(struct latched_seq *ls) | |
584 | { | |
585 | unsigned int seq; | |
586 | unsigned int idx; | |
587 | u64 val; | |
588 | ||
589 | do { | |
590 | seq = raw_read_seqcount_latch(&ls->latch); | |
591 | idx = seq & 0x1; | |
592 | val = ls->val[idx]; | |
593 | } while (read_seqcount_latch_retry(&ls->latch, seq)); | |
594 | ||
595 | return val; | |
596 | } | |
597 | ||
14c4000a VH |
598 | /* Return log buffer address */ |
599 | char *log_buf_addr_get(void) | |
600 | { | |
601 | return log_buf; | |
602 | } | |
603 | ||
604 | /* Return log buffer size */ | |
605 | u32 log_buf_len_get(void) | |
606 | { | |
607 | return log_buf_len; | |
608 | } | |
609 | ||
55bd53a4 PM |
610 | /* |
611 | * Define how much of the log buffer we could take at maximum. The value | |
612 | * must be greater than two. Note that only half of the buffer is available | |
613 | * when the index points to the middle. | |
614 | */ | |
615 | #define MAX_LOG_TAKE_PART 4 | |
616 | static const char trunc_msg[] = "<truncated>"; | |
617 | ||
896fbe20 | 618 | static void truncate_msg(u16 *text_len, u16 *trunc_msg_len) |
55bd53a4 PM |
619 | { |
620 | /* | |
621 | * The message should not take the whole buffer. Otherwise, it might | |
622 | * get removed too soon. | |
623 | */ | |
624 | u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART; | |
896fbe20 | 625 | |
55bd53a4 PM |
626 | if (*text_len > max_text_len) |
627 | *text_len = max_text_len; | |
896fbe20 JO |
628 | |
629 | /* enable the warning message (if there is room) */ | |
55bd53a4 | 630 | *trunc_msg_len = strlen(trunc_msg); |
896fbe20 JO |
631 | if (*text_len >= *trunc_msg_len) |
632 | *text_len -= *trunc_msg_len; | |
633 | else | |
634 | *trunc_msg_len = 0; | |
55bd53a4 PM |
635 | } |
636 | ||
e99aa461 | 637 | int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); |
637241a9 KC |
638 | |
639 | static int syslog_action_restricted(int type) | |
640 | { | |
641 | if (dmesg_restrict) | |
642 | return 1; | |
643 | /* | |
644 | * Unless restricted, we allow "read all" and "get buffer size" | |
645 | * for everybody. | |
646 | */ | |
647 | return type != SYSLOG_ACTION_READ_ALL && | |
648 | type != SYSLOG_ACTION_SIZE_BUFFER; | |
649 | } | |
650 | ||
c71b02e4 | 651 | static int check_syslog_permissions(int type, int source) |
637241a9 KC |
652 | { |
653 | /* | |
654 | * If this is from /proc/kmsg and we've already opened it, then we've | |
655 | * already done the capabilities checks at open time. | |
656 | */ | |
3ea4331c | 657 | if (source == SYSLOG_FROM_PROC && type != SYSLOG_ACTION_OPEN) |
d194e5d6 | 658 | goto ok; |
637241a9 KC |
659 | |
660 | if (syslog_action_restricted(type)) { | |
661 | if (capable(CAP_SYSLOG)) | |
d194e5d6 | 662 | goto ok; |
637241a9 KC |
663 | /* |
664 | * For historical reasons, accept CAP_SYS_ADMIN too, with | |
665 | * a warning. | |
666 | */ | |
667 | if (capable(CAP_SYS_ADMIN)) { | |
668 | pr_warn_once("%s (%d): Attempt to access syslog with " | |
669 | "CAP_SYS_ADMIN but no CAP_SYSLOG " | |
670 | "(deprecated).\n", | |
671 | current->comm, task_pid_nr(current)); | |
d194e5d6 | 672 | goto ok; |
637241a9 KC |
673 | } |
674 | return -EPERM; | |
675 | } | |
d194e5d6 | 676 | ok: |
637241a9 KC |
677 | return security_syslog(type); |
678 | } | |
679 | ||
d43ff430 TH |
680 | static void append_char(char **pp, char *e, char c) |
681 | { | |
682 | if (*pp < e) | |
683 | *(*pp)++ = c; | |
684 | } | |
637241a9 | 685 | |
896fbe20 JO |
686 | static ssize_t info_print_ext_header(char *buf, size_t size, |
687 | struct printk_info *info) | |
0a295e67 | 688 | { |
896fbe20 | 689 | u64 ts_usec = info->ts_nsec; |
15ff2069 TH |
690 | char caller[20]; |
691 | #ifdef CONFIG_PRINTK_CALLER | |
896fbe20 | 692 | u32 id = info->caller_id; |
15ff2069 TH |
693 | |
694 | snprintf(caller, sizeof(caller), ",caller=%c%u", | |
695 | id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); | |
696 | #else | |
697 | caller[0] = '\0'; | |
698 | #endif | |
0a295e67 TH |
699 | |
700 | do_div(ts_usec, 1000); | |
701 | ||
15ff2069 | 702 | return scnprintf(buf, size, "%u,%llu,%llu,%c%s;", |
896fbe20 JO |
703 | (info->facility << 3) | info->level, info->seq, |
704 | ts_usec, info->flags & LOG_CONT ? 'c' : '-', caller); | |
0a295e67 TH |
705 | } |
706 | ||
74caba7f JO |
707 | static ssize_t msg_add_ext_text(char *buf, size_t size, |
708 | const char *text, size_t text_len, | |
709 | unsigned char endc) | |
0a295e67 TH |
710 | { |
711 | char *p = buf, *e = buf + size; | |
712 | size_t i; | |
713 | ||
714 | /* escape non-printable characters */ | |
715 | for (i = 0; i < text_len; i++) { | |
716 | unsigned char c = text[i]; | |
717 | ||
718 | if (c < ' ' || c >= 127 || c == '\\') | |
719 | p += scnprintf(p, e - p, "\\x%02x", c); | |
720 | else | |
721 | append_char(&p, e, c); | |
722 | } | |
74caba7f | 723 | append_char(&p, e, endc); |
0a295e67 | 724 | |
74caba7f JO |
725 | return p - buf; |
726 | } | |
0a295e67 | 727 | |
74caba7f JO |
728 | static ssize_t msg_add_dict_text(char *buf, size_t size, |
729 | const char *key, const char *val) | |
730 | { | |
731 | size_t val_len = strlen(val); | |
732 | ssize_t len; | |
0a295e67 | 733 | |
74caba7f JO |
734 | if (!val_len) |
735 | return 0; | |
0a295e67 | 736 | |
74caba7f JO |
737 | len = msg_add_ext_text(buf, size, "", 0, ' '); /* dict prefix */ |
738 | len += msg_add_ext_text(buf + len, size - len, key, strlen(key), '='); | |
739 | len += msg_add_ext_text(buf + len, size - len, val, val_len, '\n'); | |
0a295e67 | 740 | |
74caba7f JO |
741 | return len; |
742 | } | |
0a295e67 | 743 | |
74caba7f JO |
744 | static ssize_t msg_print_ext_body(char *buf, size_t size, |
745 | char *text, size_t text_len, | |
746 | struct dev_printk_info *dev_info) | |
747 | { | |
748 | ssize_t len; | |
0a295e67 | 749 | |
74caba7f JO |
750 | len = msg_add_ext_text(buf, size, text, text_len, '\n'); |
751 | ||
752 | if (!dev_info) | |
753 | goto out; | |
754 | ||
755 | len += msg_add_dict_text(buf + len, size - len, "SUBSYSTEM", | |
756 | dev_info->subsystem); | |
757 | len += msg_add_dict_text(buf + len, size - len, "DEVICE", | |
758 | dev_info->device); | |
759 | out: | |
760 | return len; | |
0a295e67 TH |
761 | } |
762 | ||
e11fea92 KS |
763 | /* /dev/kmsg - userspace message inject/listen interface */ |
764 | struct devkmsg_user { | |
35b2b163 | 765 | atomic64_t seq; |
750afe7b | 766 | struct ratelimit_state rs; |
e11fea92 | 767 | struct mutex lock; |
d43ff430 | 768 | char buf[CONSOLE_EXT_LOG_MAX]; |
896fbe20 JO |
769 | |
770 | struct printk_info info; | |
771 | char text_buf[CONSOLE_EXT_LOG_MAX]; | |
896fbe20 | 772 | struct printk_record record; |
e11fea92 KS |
773 | }; |
774 | ||
9adcfaff TH |
775 | static __printf(3, 4) __cold |
776 | int devkmsg_emit(int facility, int level, const char *fmt, ...) | |
777 | { | |
778 | va_list args; | |
779 | int r; | |
780 | ||
781 | va_start(args, fmt); | |
74caba7f | 782 | r = vprintk_emit(facility, level, NULL, fmt, args); |
9adcfaff TH |
783 | va_end(args); |
784 | ||
785 | return r; | |
786 | } | |
787 | ||
849f3127 | 788 | static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from) |
e11fea92 KS |
789 | { |
790 | char *buf, *line; | |
e11fea92 KS |
791 | int level = default_message_loglevel; |
792 | int facility = 1; /* LOG_USER */ | |
750afe7b BP |
793 | struct file *file = iocb->ki_filp; |
794 | struct devkmsg_user *user = file->private_data; | |
66ee59af | 795 | size_t len = iov_iter_count(from); |
e11fea92 KS |
796 | ssize_t ret = len; |
797 | ||
750afe7b | 798 | if (!user || len > LOG_LINE_MAX) |
e11fea92 | 799 | return -EINVAL; |
750afe7b BP |
800 | |
801 | /* Ignore when user logging is disabled. */ | |
802 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) | |
803 | return len; | |
804 | ||
805 | /* Ratelimit when not explicitly enabled. */ | |
806 | if (!(devkmsg_log & DEVKMSG_LOG_MASK_ON)) { | |
807 | if (!___ratelimit(&user->rs, current->comm)) | |
808 | return ret; | |
809 | } | |
810 | ||
e11fea92 KS |
811 | buf = kmalloc(len+1, GFP_KERNEL); |
812 | if (buf == NULL) | |
813 | return -ENOMEM; | |
814 | ||
849f3127 | 815 | buf[len] = '\0'; |
cbbd26b8 | 816 | if (!copy_from_iter_full(buf, len, from)) { |
849f3127 AV |
817 | kfree(buf); |
818 | return -EFAULT; | |
e11fea92 KS |
819 | } |
820 | ||
821 | /* | |
822 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace | |
823 | * the decimal value represents 32bit, the lower 3 bit are the log | |
824 | * level, the rest are the log facility. | |
825 | * | |
826 | * If no prefix or no userspace facility is specified, we | |
827 | * enforce LOG_USER, to be able to reliably distinguish | |
828 | * kernel-generated messages from userspace-injected ones. | |
829 | */ | |
830 | line = buf; | |
831 | if (line[0] == '<') { | |
832 | char *endp = NULL; | |
3824657c | 833 | unsigned int u; |
e11fea92 | 834 | |
3824657c | 835 | u = simple_strtoul(line + 1, &endp, 10); |
e11fea92 | 836 | if (endp && endp[0] == '>') { |
3824657c MK |
837 | level = LOG_LEVEL(u); |
838 | if (LOG_FACILITY(u) != 0) | |
839 | facility = LOG_FACILITY(u); | |
e11fea92 | 840 | endp++; |
e11fea92 KS |
841 | line = endp; |
842 | } | |
843 | } | |
e11fea92 | 844 | |
9adcfaff | 845 | devkmsg_emit(facility, level, "%s", line); |
e11fea92 KS |
846 | kfree(buf); |
847 | return ret; | |
848 | } | |
849 | ||
850 | static ssize_t devkmsg_read(struct file *file, char __user *buf, | |
851 | size_t count, loff_t *ppos) | |
852 | { | |
853 | struct devkmsg_user *user = file->private_data; | |
896fbe20 | 854 | struct printk_record *r = &user->record; |
e11fea92 KS |
855 | size_t len; |
856 | ssize_t ret; | |
857 | ||
858 | if (!user) | |
859 | return -EBADF; | |
860 | ||
4a77a5a0 YL |
861 | ret = mutex_lock_interruptible(&user->lock); |
862 | if (ret) | |
863 | return ret; | |
de6fcbdb | 864 | |
35b2b163 | 865 | if (!prb_read_valid(prb, atomic64_read(&user->seq), r)) { |
e11fea92 KS |
866 | if (file->f_flags & O_NONBLOCK) { |
867 | ret = -EAGAIN; | |
e11fea92 KS |
868 | goto out; |
869 | } | |
870 | ||
1f5d7830 JO |
871 | /* |
872 | * Guarantee this task is visible on the waitqueue before | |
873 | * checking the wake condition. | |
874 | * | |
875 | * The full memory barrier within set_current_state() of | |
876 | * prepare_to_wait_event() pairs with the full memory barrier | |
877 | * within wq_has_sleeper(). | |
878 | * | |
5341b93d | 879 | * This pairs with __wake_up_klogd:A. |
1f5d7830 | 880 | */ |
e11fea92 | 881 | ret = wait_event_interruptible(log_wait, |
1f5d7830 JO |
882 | prb_read_valid(prb, |
883 | atomic64_read(&user->seq), r)); /* LMM(devkmsg_read:A) */ | |
e11fea92 KS |
884 | if (ret) |
885 | goto out; | |
e11fea92 KS |
886 | } |
887 | ||
35b2b163 | 888 | if (r->info->seq != atomic64_read(&user->seq)) { |
e11fea92 | 889 | /* our last seen message is gone, return error and reset */ |
35b2b163 | 890 | atomic64_set(&user->seq, r->info->seq); |
e11fea92 | 891 | ret = -EPIPE; |
e11fea92 KS |
892 | goto out; |
893 | } | |
894 | ||
896fbe20 | 895 | len = info_print_ext_header(user->buf, sizeof(user->buf), r->info); |
0a295e67 | 896 | len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len, |
74caba7f JO |
897 | &r->text_buf[0], r->info->text_len, |
898 | &r->info->dev_info); | |
d39f3d77 | 899 | |
35b2b163 | 900 | atomic64_set(&user->seq, r->info->seq + 1); |
e11fea92 KS |
901 | |
902 | if (len > count) { | |
903 | ret = -EINVAL; | |
904 | goto out; | |
905 | } | |
906 | ||
907 | if (copy_to_user(buf, user->buf, len)) { | |
908 | ret = -EFAULT; | |
909 | goto out; | |
910 | } | |
911 | ret = len; | |
912 | out: | |
913 | mutex_unlock(&user->lock); | |
914 | return ret; | |
915 | } | |
916 | ||
bc885f1a BM |
917 | /* |
918 | * Be careful when modifying this function!!! | |
919 | * | |
920 | * Only few operations are supported because the device works only with the | |
921 | * entire variable length messages (records). Non-standard values are | |
922 | * returned in the other cases and has been this way for quite some time. | |
923 | * User space applications might depend on this behavior. | |
924 | */ | |
e11fea92 KS |
925 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) |
926 | { | |
927 | struct devkmsg_user *user = file->private_data; | |
928 | loff_t ret = 0; | |
929 | ||
930 | if (!user) | |
931 | return -EBADF; | |
932 | if (offset) | |
933 | return -ESPIPE; | |
934 | ||
e11fea92 KS |
935 | switch (whence) { |
936 | case SEEK_SET: | |
937 | /* the first record */ | |
35b2b163 | 938 | atomic64_set(&user->seq, prb_first_valid_seq(prb)); |
e11fea92 KS |
939 | break; |
940 | case SEEK_DATA: | |
941 | /* | |
942 | * The first record after the last SYSLOG_ACTION_CLEAR, | |
943 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself | |
944 | * changes no global state, and does not clear anything. | |
945 | */ | |
35b2b163 | 946 | atomic64_set(&user->seq, latched_seq_read_nolock(&clear_seq)); |
e11fea92 KS |
947 | break; |
948 | case SEEK_END: | |
949 | /* after the last record */ | |
35b2b163 | 950 | atomic64_set(&user->seq, prb_next_seq(prb)); |
e11fea92 KS |
951 | break; |
952 | default: | |
953 | ret = -EINVAL; | |
954 | } | |
e11fea92 KS |
955 | return ret; |
956 | } | |
957 | ||
9dd95748 | 958 | static __poll_t devkmsg_poll(struct file *file, poll_table *wait) |
e11fea92 KS |
959 | { |
960 | struct devkmsg_user *user = file->private_data; | |
13791c80 | 961 | struct printk_info info; |
9dd95748 | 962 | __poll_t ret = 0; |
e11fea92 KS |
963 | |
964 | if (!user) | |
a9a08845 | 965 | return EPOLLERR|EPOLLNVAL; |
e11fea92 KS |
966 | |
967 | poll_wait(file, &log_wait, wait); | |
968 | ||
35b2b163 | 969 | if (prb_read_valid_info(prb, atomic64_read(&user->seq), &info, NULL)) { |
e11fea92 | 970 | /* return error when data has vanished underneath us */ |
35b2b163 | 971 | if (info.seq != atomic64_read(&user->seq)) |
a9a08845 | 972 | ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI; |
0a285317 | 973 | else |
a9a08845 | 974 | ret = EPOLLIN|EPOLLRDNORM; |
e11fea92 | 975 | } |
e11fea92 KS |
976 | |
977 | return ret; | |
978 | } | |
979 | ||
980 | static int devkmsg_open(struct inode *inode, struct file *file) | |
981 | { | |
982 | struct devkmsg_user *user; | |
983 | int err; | |
984 | ||
750afe7b BP |
985 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) |
986 | return -EPERM; | |
e11fea92 | 987 | |
750afe7b BP |
988 | /* write-only does not need any file context */ |
989 | if ((file->f_flags & O_ACCMODE) != O_WRONLY) { | |
990 | err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, | |
991 | SYSLOG_FROM_READER); | |
992 | if (err) | |
993 | return err; | |
994 | } | |
e11fea92 | 995 | |
9980c425 | 996 | user = kvmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); |
e11fea92 KS |
997 | if (!user) |
998 | return -ENOMEM; | |
999 | ||
750afe7b BP |
1000 | ratelimit_default_init(&user->rs); |
1001 | ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE); | |
1002 | ||
e11fea92 KS |
1003 | mutex_init(&user->lock); |
1004 | ||
896fbe20 | 1005 | prb_rec_init_rd(&user->record, &user->info, |
f35efc78 | 1006 | &user->text_buf[0], sizeof(user->text_buf)); |
896fbe20 | 1007 | |
35b2b163 | 1008 | atomic64_set(&user->seq, prb_first_valid_seq(prb)); |
e11fea92 KS |
1009 | |
1010 | file->private_data = user; | |
1011 | return 0; | |
1012 | } | |
1013 | ||
1014 | static int devkmsg_release(struct inode *inode, struct file *file) | |
1015 | { | |
1016 | struct devkmsg_user *user = file->private_data; | |
1017 | ||
1018 | if (!user) | |
1019 | return 0; | |
1020 | ||
750afe7b BP |
1021 | ratelimit_state_exit(&user->rs); |
1022 | ||
e11fea92 | 1023 | mutex_destroy(&user->lock); |
9980c425 | 1024 | kvfree(user); |
e11fea92 KS |
1025 | return 0; |
1026 | } | |
1027 | ||
1028 | const struct file_operations kmsg_fops = { | |
1029 | .open = devkmsg_open, | |
1030 | .read = devkmsg_read, | |
849f3127 | 1031 | .write_iter = devkmsg_write, |
e11fea92 KS |
1032 | .llseek = devkmsg_llseek, |
1033 | .poll = devkmsg_poll, | |
1034 | .release = devkmsg_release, | |
1035 | }; | |
1036 | ||
692f66f2 | 1037 | #ifdef CONFIG_CRASH_CORE |
04d491ab | 1038 | /* |
4c1ace64 | 1039 | * This appends the listed symbols to /proc/vmcore |
04d491ab | 1040 | * |
4c1ace64 | 1041 | * /proc/vmcore is used by various utilities, like crash and makedumpfile to |
04d491ab NH |
1042 | * obtain access to symbols that are otherwise very difficult to locate. These |
1043 | * symbols are specifically used so that utilities can access and extract the | |
1044 | * dmesg log from a vmcore file after a crash. | |
1045 | */ | |
692f66f2 | 1046 | void log_buf_vmcoreinfo_setup(void) |
04d491ab | 1047 | { |
74caba7f JO |
1048 | struct dev_printk_info *dev_info = NULL; |
1049 | ||
896fbe20 JO |
1050 | VMCOREINFO_SYMBOL(prb); |
1051 | VMCOREINFO_SYMBOL(printk_rb_static); | |
1052 | VMCOREINFO_SYMBOL(clear_seq); | |
1053 | ||
6791457a | 1054 | /* |
896fbe20 | 1055 | * Export struct size and field offsets. User space tools can |
6791457a VG |
1056 | * parse it and detect any changes to structure down the line. |
1057 | */ | |
896fbe20 JO |
1058 | |
1059 | VMCOREINFO_STRUCT_SIZE(printk_ringbuffer); | |
1060 | VMCOREINFO_OFFSET(printk_ringbuffer, desc_ring); | |
1061 | VMCOREINFO_OFFSET(printk_ringbuffer, text_data_ring); | |
896fbe20 JO |
1062 | VMCOREINFO_OFFSET(printk_ringbuffer, fail); |
1063 | ||
1064 | VMCOREINFO_STRUCT_SIZE(prb_desc_ring); | |
1065 | VMCOREINFO_OFFSET(prb_desc_ring, count_bits); | |
1066 | VMCOREINFO_OFFSET(prb_desc_ring, descs); | |
cfe2790b | 1067 | VMCOREINFO_OFFSET(prb_desc_ring, infos); |
896fbe20 JO |
1068 | VMCOREINFO_OFFSET(prb_desc_ring, head_id); |
1069 | VMCOREINFO_OFFSET(prb_desc_ring, tail_id); | |
1070 | ||
1071 | VMCOREINFO_STRUCT_SIZE(prb_desc); | |
896fbe20 JO |
1072 | VMCOREINFO_OFFSET(prb_desc, state_var); |
1073 | VMCOREINFO_OFFSET(prb_desc, text_blk_lpos); | |
896fbe20 JO |
1074 | |
1075 | VMCOREINFO_STRUCT_SIZE(prb_data_blk_lpos); | |
1076 | VMCOREINFO_OFFSET(prb_data_blk_lpos, begin); | |
1077 | VMCOREINFO_OFFSET(prb_data_blk_lpos, next); | |
1078 | ||
1079 | VMCOREINFO_STRUCT_SIZE(printk_info); | |
1080 | VMCOREINFO_OFFSET(printk_info, seq); | |
1081 | VMCOREINFO_OFFSET(printk_info, ts_nsec); | |
1082 | VMCOREINFO_OFFSET(printk_info, text_len); | |
896fbe20 | 1083 | VMCOREINFO_OFFSET(printk_info, caller_id); |
74caba7f JO |
1084 | VMCOREINFO_OFFSET(printk_info, dev_info); |
1085 | ||
1086 | VMCOREINFO_STRUCT_SIZE(dev_printk_info); | |
1087 | VMCOREINFO_OFFSET(dev_printk_info, subsystem); | |
1088 | VMCOREINFO_LENGTH(printk_info_subsystem, sizeof(dev_info->subsystem)); | |
1089 | VMCOREINFO_OFFSET(dev_printk_info, device); | |
1090 | VMCOREINFO_LENGTH(printk_info_device, sizeof(dev_info->device)); | |
896fbe20 JO |
1091 | |
1092 | VMCOREINFO_STRUCT_SIZE(prb_data_ring); | |
1093 | VMCOREINFO_OFFSET(prb_data_ring, size_bits); | |
1094 | VMCOREINFO_OFFSET(prb_data_ring, data); | |
1095 | VMCOREINFO_OFFSET(prb_data_ring, head_lpos); | |
1096 | VMCOREINFO_OFFSET(prb_data_ring, tail_lpos); | |
1097 | ||
1098 | VMCOREINFO_SIZE(atomic_long_t); | |
1099 | VMCOREINFO_TYPE_OFFSET(atomic_long_t, counter); | |
7d7a23a9 JO |
1100 | |
1101 | VMCOREINFO_STRUCT_SIZE(latched_seq); | |
1102 | VMCOREINFO_OFFSET(latched_seq, val); | |
04d491ab NH |
1103 | } |
1104 | #endif | |
1105 | ||
162a7e75 MT |
1106 | /* requested log_buf_len from kernel cmdline */ |
1107 | static unsigned long __initdata new_log_buf_len; | |
1108 | ||
c0a318a3 | 1109 | /* we practice scaling the ring buffer by powers of 2 */ |
e6fe3e5b | 1110 | static void __init log_buf_len_update(u64 size) |
1da177e4 | 1111 | { |
e6fe3e5b HZ |
1112 | if (size > (u64)LOG_BUF_LEN_MAX) { |
1113 | size = (u64)LOG_BUF_LEN_MAX; | |
1114 | pr_err("log_buf over 2G is not supported.\n"); | |
1115 | } | |
1116 | ||
1da177e4 LT |
1117 | if (size) |
1118 | size = roundup_pow_of_two(size); | |
162a7e75 | 1119 | if (size > log_buf_len) |
e6fe3e5b | 1120 | new_log_buf_len = (unsigned long)size; |
c0a318a3 LR |
1121 | } |
1122 | ||
1123 | /* save requested log_buf_len since it's too early to process it */ | |
1124 | static int __init log_buf_len_setup(char *str) | |
1125 | { | |
e6fe3e5b | 1126 | u64 size; |
277fcdb2 HZ |
1127 | |
1128 | if (!str) | |
1129 | return -EINVAL; | |
1130 | ||
1131 | size = memparse(str, &str); | |
c0a318a3 LR |
1132 | |
1133 | log_buf_len_update(size); | |
162a7e75 MT |
1134 | |
1135 | return 0; | |
1da177e4 | 1136 | } |
162a7e75 MT |
1137 | early_param("log_buf_len", log_buf_len_setup); |
1138 | ||
2240a31d GU |
1139 | #ifdef CONFIG_SMP |
1140 | #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) | |
1141 | ||
23b2899f LR |
1142 | static void __init log_buf_add_cpu(void) |
1143 | { | |
1144 | unsigned int cpu_extra; | |
1145 | ||
1146 | /* | |
1147 | * archs should set up cpu_possible_bits properly with | |
1148 | * set_cpu_possible() after setup_arch() but just in | |
1149 | * case lets ensure this is valid. | |
1150 | */ | |
1151 | if (num_possible_cpus() == 1) | |
1152 | return; | |
1153 | ||
1154 | cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; | |
1155 | ||
1156 | /* by default this will only continue through for large > 64 CPUs */ | |
1157 | if (cpu_extra <= __LOG_BUF_LEN / 2) | |
1158 | return; | |
1159 | ||
1160 | pr_info("log_buf_len individual max cpu contribution: %d bytes\n", | |
1161 | __LOG_CPU_MAX_BUF_LEN); | |
1162 | pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", | |
1163 | cpu_extra); | |
1164 | pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); | |
1165 | ||
1166 | log_buf_len_update(cpu_extra + __LOG_BUF_LEN); | |
1167 | } | |
2240a31d GU |
1168 | #else /* !CONFIG_SMP */ |
1169 | static inline void log_buf_add_cpu(void) {} | |
1170 | #endif /* CONFIG_SMP */ | |
23b2899f | 1171 | |
ab6f762f SS |
1172 | static void __init set_percpu_data_ready(void) |
1173 | { | |
ab6f762f SS |
1174 | __printk_percpu_data_ready = true; |
1175 | } | |
1176 | ||
896fbe20 JO |
1177 | static unsigned int __init add_to_rb(struct printk_ringbuffer *rb, |
1178 | struct printk_record *r) | |
1179 | { | |
1180 | struct prb_reserved_entry e; | |
1181 | struct printk_record dest_r; | |
1182 | ||
f35efc78 | 1183 | prb_rec_init_wr(&dest_r, r->info->text_len); |
896fbe20 JO |
1184 | |
1185 | if (!prb_reserve(&e, rb, &dest_r)) | |
1186 | return 0; | |
1187 | ||
cc5c7041 JO |
1188 | memcpy(&dest_r.text_buf[0], &r->text_buf[0], r->info->text_len); |
1189 | dest_r.info->text_len = r->info->text_len; | |
896fbe20 JO |
1190 | dest_r.info->facility = r->info->facility; |
1191 | dest_r.info->level = r->info->level; | |
1192 | dest_r.info->flags = r->info->flags; | |
1193 | dest_r.info->ts_nsec = r->info->ts_nsec; | |
1194 | dest_r.info->caller_id = r->info->caller_id; | |
74caba7f | 1195 | memcpy(&dest_r.info->dev_info, &r->info->dev_info, sizeof(dest_r.info->dev_info)); |
896fbe20 | 1196 | |
f5f022e5 | 1197 | prb_final_commit(&e); |
896fbe20 JO |
1198 | |
1199 | return prb_record_text_space(&e); | |
1200 | } | |
1201 | ||
0463d04e | 1202 | static char setup_text_buf[LOG_LINE_MAX] __initdata; |
896fbe20 | 1203 | |
162a7e75 MT |
1204 | void __init setup_log_buf(int early) |
1205 | { | |
cfe2790b | 1206 | struct printk_info *new_infos; |
896fbe20 JO |
1207 | unsigned int new_descs_count; |
1208 | struct prb_desc *new_descs; | |
1209 | struct printk_info info; | |
1210 | struct printk_record r; | |
93d102f0 | 1211 | unsigned int text_size; |
896fbe20 | 1212 | size_t new_descs_size; |
cfe2790b | 1213 | size_t new_infos_size; |
162a7e75 | 1214 | unsigned long flags; |
162a7e75 | 1215 | char *new_log_buf; |
d2130e82 | 1216 | unsigned int free; |
896fbe20 | 1217 | u64 seq; |
162a7e75 | 1218 | |
ab6f762f SS |
1219 | /* |
1220 | * Some archs call setup_log_buf() multiple times - first is very | |
1221 | * early, e.g. from setup_arch(), and second - when percpu_areas | |
1222 | * are initialised. | |
1223 | */ | |
1224 | if (!early) | |
1225 | set_percpu_data_ready(); | |
1226 | ||
23b2899f LR |
1227 | if (log_buf != __log_buf) |
1228 | return; | |
1229 | ||
1230 | if (!early && !new_log_buf_len) | |
1231 | log_buf_add_cpu(); | |
1232 | ||
162a7e75 MT |
1233 | if (!new_log_buf_len) |
1234 | return; | |
1da177e4 | 1235 | |
896fbe20 JO |
1236 | new_descs_count = new_log_buf_len >> PRB_AVGBITS; |
1237 | if (new_descs_count == 0) { | |
1238 | pr_err("new_log_buf_len: %lu too small\n", new_log_buf_len); | |
1239 | return; | |
1240 | } | |
1241 | ||
26fb3dae | 1242 | new_log_buf = memblock_alloc(new_log_buf_len, LOG_ALIGN); |
162a7e75 | 1243 | if (unlikely(!new_log_buf)) { |
896fbe20 JO |
1244 | pr_err("log_buf_len: %lu text bytes not available\n", |
1245 | new_log_buf_len); | |
162a7e75 MT |
1246 | return; |
1247 | } | |
1248 | ||
896fbe20 JO |
1249 | new_descs_size = new_descs_count * sizeof(struct prb_desc); |
1250 | new_descs = memblock_alloc(new_descs_size, LOG_ALIGN); | |
1251 | if (unlikely(!new_descs)) { | |
1252 | pr_err("log_buf_len: %zu desc bytes not available\n", | |
1253 | new_descs_size); | |
f35efc78 | 1254 | goto err_free_log_buf; |
cfe2790b JO |
1255 | } |
1256 | ||
1257 | new_infos_size = new_descs_count * sizeof(struct printk_info); | |
1258 | new_infos = memblock_alloc(new_infos_size, LOG_ALIGN); | |
1259 | if (unlikely(!new_infos)) { | |
1260 | pr_err("log_buf_len: %zu info bytes not available\n", | |
1261 | new_infos_size); | |
1262 | goto err_free_descs; | |
896fbe20 JO |
1263 | } |
1264 | ||
f35efc78 | 1265 | prb_rec_init_rd(&r, &info, &setup_text_buf[0], sizeof(setup_text_buf)); |
896fbe20 JO |
1266 | |
1267 | prb_init(&printk_rb_dynamic, | |
1268 | new_log_buf, ilog2(new_log_buf_len), | |
cfe2790b JO |
1269 | new_descs, ilog2(new_descs_count), |
1270 | new_infos); | |
896fbe20 | 1271 | |
93d102f0 | 1272 | local_irq_save(flags); |
896fbe20 | 1273 | |
162a7e75 MT |
1274 | log_buf_len = new_log_buf_len; |
1275 | log_buf = new_log_buf; | |
1276 | new_log_buf_len = 0; | |
896fbe20 JO |
1277 | |
1278 | free = __LOG_BUF_LEN; | |
93d102f0 JO |
1279 | prb_for_each_record(0, &printk_rb_static, seq, &r) { |
1280 | text_size = add_to_rb(&printk_rb_dynamic, &r); | |
1281 | if (text_size > free) | |
1282 | free = 0; | |
1283 | else | |
1284 | free -= text_size; | |
1285 | } | |
896fbe20 | 1286 | |
896fbe20 JO |
1287 | prb = &printk_rb_dynamic; |
1288 | ||
93d102f0 JO |
1289 | local_irq_restore(flags); |
1290 | ||
1291 | /* | |
1292 | * Copy any remaining messages that might have appeared from | |
1293 | * NMI context after copying but before switching to the | |
1294 | * dynamic buffer. | |
1295 | */ | |
1296 | prb_for_each_record(seq, &printk_rb_static, seq, &r) { | |
1297 | text_size = add_to_rb(&printk_rb_dynamic, &r); | |
1298 | if (text_size > free) | |
1299 | free = 0; | |
1300 | else | |
1301 | free -= text_size; | |
1302 | } | |
162a7e75 | 1303 | |
896fbe20 JO |
1304 | if (seq != prb_next_seq(&printk_rb_static)) { |
1305 | pr_err("dropped %llu messages\n", | |
1306 | prb_next_seq(&printk_rb_static) - seq); | |
1307 | } | |
1308 | ||
e6fe3e5b HZ |
1309 | pr_info("log_buf_len: %u bytes\n", log_buf_len); |
1310 | pr_info("early log buf free: %u(%u%%)\n", | |
162a7e75 | 1311 | free, (free * 100) / __LOG_BUF_LEN); |
cfe2790b JO |
1312 | return; |
1313 | ||
1314 | err_free_descs: | |
4421cca0 | 1315 | memblock_free(new_descs, new_descs_size); |
cfe2790b | 1316 | err_free_log_buf: |
4421cca0 | 1317 | memblock_free(new_log_buf, new_log_buf_len); |
162a7e75 | 1318 | } |
1da177e4 | 1319 | |
2fa72c8f AC |
1320 | static bool __read_mostly ignore_loglevel; |
1321 | ||
1322 | static int __init ignore_loglevel_setup(char *str) | |
1323 | { | |
d25d9fec | 1324 | ignore_loglevel = true; |
27083bac | 1325 | pr_info("debug: ignoring loglevel setting.\n"); |
2fa72c8f AC |
1326 | |
1327 | return 0; | |
1328 | } | |
1329 | ||
1330 | early_param("ignore_loglevel", ignore_loglevel_setup); | |
1331 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); | |
205bd3d2 JP |
1332 | MODULE_PARM_DESC(ignore_loglevel, |
1333 | "ignore loglevel setting (prints all kernel messages to the console)"); | |
2fa72c8f | 1334 | |
cf775444 SS |
1335 | static bool suppress_message_printing(int level) |
1336 | { | |
1337 | return (level >= console_loglevel && !ignore_loglevel); | |
1338 | } | |
1339 | ||
bfe8df3d RD |
1340 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
1341 | ||
674dff65 | 1342 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 1343 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
1344 | |
1345 | static int __init boot_delay_setup(char *str) | |
1346 | { | |
1347 | unsigned long lpj; | |
bfe8df3d RD |
1348 | |
1349 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
1350 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
1351 | ||
1352 | get_option(&str, &boot_delay); | |
1353 | if (boot_delay > 10 * 1000) | |
1354 | boot_delay = 0; | |
1355 | ||
3a3b6ed2 DY |
1356 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
1357 | "HZ: %d, loops_per_msec: %llu\n", | |
1358 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
29e9d225 | 1359 | return 0; |
bfe8df3d | 1360 | } |
29e9d225 | 1361 | early_param("boot_delay", boot_delay_setup); |
bfe8df3d | 1362 | |
2fa72c8f | 1363 | static void boot_delay_msec(int level) |
bfe8df3d RD |
1364 | { |
1365 | unsigned long long k; | |
1366 | unsigned long timeout; | |
1367 | ||
ff48cd26 | 1368 | if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING) |
cf775444 | 1369 | || suppress_message_printing(level)) { |
bfe8df3d | 1370 | return; |
2fa72c8f | 1371 | } |
bfe8df3d | 1372 | |
3a3b6ed2 | 1373 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
1374 | |
1375 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
1376 | while (k) { | |
1377 | k--; | |
1378 | cpu_relax(); | |
1379 | /* | |
1380 | * use (volatile) jiffies to prevent | |
1381 | * compiler reduction; loop termination via jiffies | |
1382 | * is secondary and may or may not happen. | |
1383 | */ | |
1384 | if (time_after(jiffies, timeout)) | |
1385 | break; | |
1386 | touch_nmi_watchdog(); | |
1387 | } | |
1388 | } | |
1389 | #else | |
2fa72c8f | 1390 | static inline void boot_delay_msec(int level) |
bfe8df3d RD |
1391 | { |
1392 | } | |
1393 | #endif | |
1394 | ||
e99aa461 | 1395 | static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); |
7ff9554b KS |
1396 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1397 | ||
07c17732 | 1398 | static size_t print_syslog(unsigned int level, char *buf) |
084681d1 | 1399 | { |
07c17732 TH |
1400 | return sprintf(buf, "<%u>", level); |
1401 | } | |
35dac27c | 1402 | |
084681d1 KS |
1403 | static size_t print_time(u64 ts, char *buf) |
1404 | { | |
e80c1a9d | 1405 | unsigned long rem_nsec = do_div(ts, 1000000000); |
084681d1 | 1406 | |
15ff2069 | 1407 | return sprintf(buf, "[%5lu.%06lu]", |
084681d1 KS |
1408 | (unsigned long)ts, rem_nsec / 1000); |
1409 | } | |
1410 | ||
15ff2069 TH |
1411 | #ifdef CONFIG_PRINTK_CALLER |
1412 | static size_t print_caller(u32 id, char *buf) | |
1413 | { | |
1414 | char caller[12]; | |
1415 | ||
1416 | snprintf(caller, sizeof(caller), "%c%u", | |
1417 | id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); | |
1418 | return sprintf(buf, "[%6s]", caller); | |
1419 | } | |
1420 | #else | |
1421 | #define print_caller(id, buf) 0 | |
1422 | #endif | |
1423 | ||
896fbe20 JO |
1424 | static size_t info_print_prefix(const struct printk_info *info, bool syslog, |
1425 | bool time, char *buf) | |
649e6ee3 | 1426 | { |
3ce9a7c0 | 1427 | size_t len = 0; |
649e6ee3 | 1428 | |
07c17732 | 1429 | if (syslog) |
896fbe20 | 1430 | len = print_syslog((info->facility << 3) | info->level, buf); |
15ff2069 | 1431 | |
e80c1a9d | 1432 | if (time) |
896fbe20 | 1433 | len += print_time(info->ts_nsec, buf + len); |
15ff2069 | 1434 | |
896fbe20 | 1435 | len += print_caller(info->caller_id, buf + len); |
15ff2069 TH |
1436 | |
1437 | if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) { | |
1438 | buf[len++] = ' '; | |
1439 | buf[len] = '\0'; | |
1440 | } | |
1441 | ||
3ce9a7c0 | 1442 | return len; |
649e6ee3 KS |
1443 | } |
1444 | ||
896fbe20 JO |
1445 | /* |
1446 | * Prepare the record for printing. The text is shifted within the given | |
1447 | * buffer to avoid a need for another one. The following operations are | |
1448 | * done: | |
1449 | * | |
1450 | * - Add prefix for each line. | |
f0e386ee | 1451 | * - Drop truncated lines that no longer fit into the buffer. |
896fbe20 | 1452 | * - Add the trailing newline that has been removed in vprintk_store(). |
f0e386ee JO |
1453 | * - Add a string terminator. |
1454 | * | |
1455 | * Since the produced string is always terminated, the maximum possible | |
1456 | * return value is @r->text_buf_size - 1; | |
896fbe20 JO |
1457 | * |
1458 | * Return: The length of the updated/prepared text, including the added | |
f0e386ee JO |
1459 | * prefixes and the newline. The terminator is not counted. The dropped |
1460 | * line(s) are not counted. | |
896fbe20 JO |
1461 | */ |
1462 | static size_t record_print_text(struct printk_record *r, bool syslog, | |
1463 | bool time) | |
7ff9554b | 1464 | { |
896fbe20 JO |
1465 | size_t text_len = r->info->text_len; |
1466 | size_t buf_size = r->text_buf_size; | |
1467 | char *text = r->text_buf; | |
07c17732 | 1468 | char prefix[PREFIX_MAX]; |
896fbe20 JO |
1469 | bool truncated = false; |
1470 | size_t prefix_len; | |
1471 | size_t line_len; | |
1472 | size_t len = 0; | |
1473 | char *next; | |
3ce9a7c0 | 1474 | |
59f8bcca JO |
1475 | /* |
1476 | * If the message was truncated because the buffer was not large | |
1477 | * enough, treat the available text as if it were the full text. | |
1478 | */ | |
1479 | if (text_len > buf_size) | |
1480 | text_len = buf_size; | |
3ce9a7c0 | 1481 | |
896fbe20 | 1482 | prefix_len = info_print_prefix(r->info, syslog, time, prefix); |
3ce9a7c0 | 1483 | |
896fbe20 JO |
1484 | /* |
1485 | * @text_len: bytes of unprocessed text | |
1486 | * @line_len: bytes of current line _without_ newline | |
1487 | * @text: pointer to beginning of current line | |
1488 | * @len: number of bytes prepared in r->text_buf | |
1489 | */ | |
1490 | for (;;) { | |
1491 | next = memchr(text, '\n', text_len); | |
3ce9a7c0 | 1492 | if (next) { |
896fbe20 | 1493 | line_len = next - text; |
3ce9a7c0 | 1494 | } else { |
896fbe20 JO |
1495 | /* Drop truncated line(s). */ |
1496 | if (truncated) | |
1497 | break; | |
1498 | line_len = text_len; | |
3ce9a7c0 | 1499 | } |
7ff9554b | 1500 | |
896fbe20 JO |
1501 | /* |
1502 | * Truncate the text if there is not enough space to add the | |
f0e386ee | 1503 | * prefix and a trailing newline and a terminator. |
896fbe20 | 1504 | */ |
f0e386ee | 1505 | if (len + prefix_len + text_len + 1 + 1 > buf_size) { |
896fbe20 | 1506 | /* Drop even the current line if no space. */ |
f0e386ee | 1507 | if (len + prefix_len + line_len + 1 + 1 > buf_size) |
3ce9a7c0 | 1508 | break; |
7ff9554b | 1509 | |
f0e386ee | 1510 | text_len = buf_size - len - prefix_len - 1 - 1; |
896fbe20 | 1511 | truncated = true; |
3ce9a7c0 | 1512 | } |
7ff9554b | 1513 | |
896fbe20 JO |
1514 | memmove(text + prefix_len, text, text_len); |
1515 | memcpy(text, prefix, prefix_len); | |
1516 | ||
f0e386ee JO |
1517 | /* |
1518 | * Increment the prepared length to include the text and | |
1519 | * prefix that were just moved+copied. Also increment for the | |
1520 | * newline at the end of this line. If this is the last line, | |
1521 | * there is no newline, but it will be added immediately below. | |
1522 | */ | |
896fbe20 | 1523 | len += prefix_len + line_len + 1; |
896fbe20 JO |
1524 | if (text_len == line_len) { |
1525 | /* | |
f0e386ee JO |
1526 | * This is the last line. Add the trailing newline |
1527 | * removed in vprintk_store(). | |
896fbe20 JO |
1528 | */ |
1529 | text[prefix_len + line_len] = '\n'; | |
1530 | break; | |
1531 | } | |
1532 | ||
1533 | /* | |
1534 | * Advance beyond the added prefix and the related line with | |
1535 | * its newline. | |
1536 | */ | |
1537 | text += prefix_len + line_len + 1; | |
1538 | ||
1539 | /* | |
1540 | * The remaining text has only decreased by the line with its | |
1541 | * newline. | |
1542 | * | |
1543 | * Note that @text_len can become zero. It happens when @text | |
1544 | * ended with a newline (either due to truncation or the | |
1545 | * original string ending with "\n\n"). The loop is correctly | |
1546 | * repeated and (if not truncated) an empty line with a prefix | |
1547 | * will be prepared. | |
1548 | */ | |
1549 | text_len -= line_len + 1; | |
1550 | } | |
7ff9554b | 1551 | |
f0e386ee JO |
1552 | /* |
1553 | * If a buffer was provided, it will be terminated. Space for the | |
1554 | * string terminator is guaranteed to be available. The terminator is | |
1555 | * not counted in the return value. | |
1556 | */ | |
1557 | if (buf_size > 0) | |
08d60e59 | 1558 | r->text_buf[len] = 0; |
f0e386ee | 1559 | |
7ff9554b KS |
1560 | return len; |
1561 | } | |
1562 | ||
896fbe20 JO |
1563 | static size_t get_record_print_text_size(struct printk_info *info, |
1564 | unsigned int line_count, | |
1565 | bool syslog, bool time) | |
1566 | { | |
1567 | char prefix[PREFIX_MAX]; | |
1568 | size_t prefix_len; | |
1569 | ||
1570 | prefix_len = info_print_prefix(info, syslog, time, prefix); | |
1571 | ||
1572 | /* | |
1573 | * Each line will be preceded with a prefix. The intermediate | |
1574 | * newlines are already within the text, but a final trailing | |
1575 | * newline will be added. | |
1576 | */ | |
1577 | return ((prefix_len * line_count) + info->text_len + 1); | |
1578 | } | |
1579 | ||
4260e0e5 JO |
1580 | /* |
1581 | * Beginning with @start_seq, find the first record where it and all following | |
1582 | * records up to (but not including) @max_seq fit into @size. | |
1583 | * | |
1584 | * @max_seq is simply an upper bound and does not need to exist. If the caller | |
1585 | * does not require an upper bound, -1 can be used for @max_seq. | |
1586 | */ | |
1587 | static u64 find_first_fitting_seq(u64 start_seq, u64 max_seq, size_t size, | |
1588 | bool syslog, bool time) | |
1589 | { | |
1590 | struct printk_info info; | |
1591 | unsigned int line_count; | |
1592 | size_t len = 0; | |
1593 | u64 seq; | |
1594 | ||
1595 | /* Determine the size of the records up to @max_seq. */ | |
1596 | prb_for_each_info(start_seq, prb, seq, &info, &line_count) { | |
1597 | if (info.seq >= max_seq) | |
1598 | break; | |
1599 | len += get_record_print_text_size(&info, line_count, syslog, time); | |
1600 | } | |
1601 | ||
1602 | /* | |
1603 | * Adjust the upper bound for the next loop to avoid subtracting | |
1604 | * lengths that were never added. | |
1605 | */ | |
1606 | if (seq < max_seq) | |
1607 | max_seq = seq; | |
1608 | ||
1609 | /* | |
1610 | * Move first record forward until length fits into the buffer. Ignore | |
1611 | * newest messages that were not counted in the above cycle. Messages | |
1612 | * might appear and get lost in the meantime. This is a best effort | |
1613 | * that prevents an infinite loop that could occur with a retry. | |
1614 | */ | |
1615 | prb_for_each_info(start_seq, prb, seq, &info, &line_count) { | |
1616 | if (len <= size || info.seq >= max_seq) | |
1617 | break; | |
1618 | len -= get_record_print_text_size(&info, line_count, syslog, time); | |
1619 | } | |
1620 | ||
1621 | return seq; | |
1622 | } | |
1623 | ||
8d909b23 | 1624 | /* The caller is responsible for making sure @size is greater than 0. */ |
7ff9554b KS |
1625 | static int syslog_print(char __user *buf, int size) |
1626 | { | |
896fbe20 JO |
1627 | struct printk_info info; |
1628 | struct printk_record r; | |
7ff9554b | 1629 | char *text; |
116e90b2 | 1630 | int len = 0; |
8d909b23 | 1631 | u64 seq; |
7ff9554b | 1632 | |
cf5b0208 | 1633 | text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL); |
7ff9554b KS |
1634 | if (!text) |
1635 | return -ENOMEM; | |
1636 | ||
cf5b0208 | 1637 | prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX); |
896fbe20 | 1638 | |
8d909b23 JO |
1639 | mutex_lock(&syslog_lock); |
1640 | ||
1641 | /* | |
1642 | * Wait for the @syslog_seq record to be available. @syslog_seq may | |
1643 | * change while waiting. | |
1644 | */ | |
1645 | do { | |
1646 | seq = syslog_seq; | |
1647 | ||
1648 | mutex_unlock(&syslog_lock); | |
1f5d7830 JO |
1649 | /* |
1650 | * Guarantee this task is visible on the waitqueue before | |
1651 | * checking the wake condition. | |
1652 | * | |
1653 | * The full memory barrier within set_current_state() of | |
1654 | * prepare_to_wait_event() pairs with the full memory barrier | |
1655 | * within wq_has_sleeper(). | |
1656 | * | |
5341b93d | 1657 | * This pairs with __wake_up_klogd:A. |
1f5d7830 JO |
1658 | */ |
1659 | len = wait_event_interruptible(log_wait, | |
1660 | prb_read_valid(prb, seq, NULL)); /* LMM(syslog_print:A) */ | |
8d909b23 JO |
1661 | mutex_lock(&syslog_lock); |
1662 | ||
1663 | if (len) | |
1664 | goto out; | |
1665 | } while (syslog_seq != seq); | |
1666 | ||
1667 | /* | |
1668 | * Copy records that fit into the buffer. The above cycle makes sure | |
1669 | * that the first record is always available. | |
1670 | */ | |
1671 | do { | |
116e90b2 | 1672 | size_t n; |
eb02dac9 | 1673 | size_t skip; |
8d909b23 | 1674 | int err; |
116e90b2 | 1675 | |
8d909b23 | 1676 | if (!prb_read_valid(prb, syslog_seq, &r)) |
116e90b2 | 1677 | break; |
8d909b23 | 1678 | |
896fbe20 JO |
1679 | if (r.info->seq != syslog_seq) { |
1680 | /* message is gone, move to next valid one */ | |
1681 | syslog_seq = r.info->seq; | |
1682 | syslog_partial = 0; | |
1683 | } | |
eb02dac9 | 1684 | |
e80c1a9d TH |
1685 | /* |
1686 | * To keep reading/counting partial line consistent, | |
1687 | * use printk_time value as of the beginning of a line. | |
1688 | */ | |
1689 | if (!syslog_partial) | |
1690 | syslog_time = printk_time; | |
1691 | ||
eb02dac9 | 1692 | skip = syslog_partial; |
896fbe20 | 1693 | n = record_print_text(&r, true, syslog_time); |
eb02dac9 KS |
1694 | if (n - syslog_partial <= size) { |
1695 | /* message fits into buffer, move forward */ | |
896fbe20 | 1696 | syslog_seq = r.info->seq + 1; |
eb02dac9 KS |
1697 | n -= syslog_partial; |
1698 | syslog_partial = 0; | |
1699 | } else if (!len){ | |
1700 | /* partial read(), remember position */ | |
1701 | n = size; | |
1702 | syslog_partial += n; | |
116e90b2 JB |
1703 | } else |
1704 | n = 0; | |
116e90b2 JB |
1705 | |
1706 | if (!n) | |
1707 | break; | |
1708 | ||
8d909b23 JO |
1709 | mutex_unlock(&syslog_lock); |
1710 | err = copy_to_user(buf, text + skip, n); | |
1711 | mutex_lock(&syslog_lock); | |
1712 | ||
1713 | if (err) { | |
116e90b2 JB |
1714 | if (!len) |
1715 | len = -EFAULT; | |
1716 | break; | |
1717 | } | |
eb02dac9 KS |
1718 | |
1719 | len += n; | |
1720 | size -= n; | |
1721 | buf += n; | |
8d909b23 JO |
1722 | } while (size); |
1723 | out: | |
1724 | mutex_unlock(&syslog_lock); | |
7ff9554b KS |
1725 | kfree(text); |
1726 | return len; | |
1727 | } | |
1728 | ||
1729 | static int syslog_print_all(char __user *buf, int size, bool clear) | |
1730 | { | |
896fbe20 | 1731 | struct printk_info info; |
896fbe20 | 1732 | struct printk_record r; |
7ff9554b KS |
1733 | char *text; |
1734 | int len = 0; | |
63842c21 | 1735 | u64 seq; |
e80c1a9d | 1736 | bool time; |
63842c21 | 1737 | |
cf5b0208 | 1738 | text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL); |
7ff9554b KS |
1739 | if (!text) |
1740 | return -ENOMEM; | |
1741 | ||
e80c1a9d | 1742 | time = printk_time; |
63842c21 NG |
1743 | /* |
1744 | * Find first record that fits, including all following records, | |
1745 | * into the user-provided buffer for this dump. | |
1746 | */ | |
7d7a23a9 JO |
1747 | seq = find_first_fitting_seq(latched_seq_read_nolock(&clear_seq), -1, |
1748 | size, true, time); | |
7ff9554b | 1749 | |
cf5b0208 | 1750 | prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX); |
7ff9554b | 1751 | |
63842c21 | 1752 | len = 0; |
896fbe20 JO |
1753 | prb_for_each_record(seq, prb, seq, &r) { |
1754 | int textlen; | |
7ff9554b | 1755 | |
896fbe20 JO |
1756 | textlen = record_print_text(&r, true, time); |
1757 | ||
1758 | if (len + textlen > size) { | |
1759 | seq--; | |
1760 | break; | |
1761 | } | |
7ff9554b | 1762 | |
63842c21 NG |
1763 | if (copy_to_user(buf + len, text, textlen)) |
1764 | len = -EFAULT; | |
1765 | else | |
1766 | len += textlen; | |
7ff9554b | 1767 | |
896fbe20 JO |
1768 | if (len < 0) |
1769 | break; | |
7ff9554b KS |
1770 | } |
1771 | ||
636babdc | 1772 | if (clear) { |
b371cbb5 | 1773 | mutex_lock(&syslog_lock); |
7d7a23a9 | 1774 | latched_seq_write(&clear_seq, seq); |
b371cbb5 | 1775 | mutex_unlock(&syslog_lock); |
636babdc | 1776 | } |
7ff9554b KS |
1777 | |
1778 | kfree(text); | |
1779 | return len; | |
1780 | } | |
1781 | ||
8599dc7d PM |
1782 | static void syslog_clear(void) |
1783 | { | |
b371cbb5 | 1784 | mutex_lock(&syslog_lock); |
7d7a23a9 | 1785 | latched_seq_write(&clear_seq, prb_next_seq(prb)); |
b371cbb5 | 1786 | mutex_unlock(&syslog_lock); |
636babdc JO |
1787 | } |
1788 | ||
3ea4331c | 1789 | int do_syslog(int type, char __user *buf, int len, int source) |
1da177e4 | 1790 | { |
13791c80 | 1791 | struct printk_info info; |
7ff9554b | 1792 | bool clear = false; |
a39d4a85 | 1793 | static int saved_console_loglevel = LOGLEVEL_DEFAULT; |
ee24aebf | 1794 | int error; |
1da177e4 | 1795 | |
3ea4331c | 1796 | error = check_syslog_permissions(type, source); |
ee24aebf | 1797 | if (error) |
077a1cc0 | 1798 | return error; |
12b3052c | 1799 | |
1da177e4 | 1800 | switch (type) { |
d78ca3cd | 1801 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 1802 | break; |
d78ca3cd | 1803 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 1804 | break; |
d78ca3cd | 1805 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 | 1806 | if (!buf || len < 0) |
077a1cc0 | 1807 | return -EINVAL; |
1da177e4 | 1808 | if (!len) |
077a1cc0 | 1809 | return 0; |
96d4f267 | 1810 | if (!access_ok(buf, len)) |
077a1cc0 | 1811 | return -EFAULT; |
7ff9554b | 1812 | error = syslog_print(buf, len); |
1da177e4 | 1813 | break; |
d78ca3cd KC |
1814 | /* Read/clear last kernel messages */ |
1815 | case SYSLOG_ACTION_READ_CLEAR: | |
7ff9554b | 1816 | clear = true; |
4e797e6e | 1817 | fallthrough; |
d78ca3cd KC |
1818 | /* Read last kernel messages */ |
1819 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 | 1820 | if (!buf || len < 0) |
077a1cc0 | 1821 | return -EINVAL; |
1da177e4 | 1822 | if (!len) |
077a1cc0 | 1823 | return 0; |
96d4f267 | 1824 | if (!access_ok(buf, len)) |
077a1cc0 | 1825 | return -EFAULT; |
7ff9554b | 1826 | error = syslog_print_all(buf, len, clear); |
1da177e4 | 1827 | break; |
d78ca3cd KC |
1828 | /* Clear ring buffer */ |
1829 | case SYSLOG_ACTION_CLEAR: | |
8599dc7d | 1830 | syslog_clear(); |
4661e356 | 1831 | break; |
d78ca3cd KC |
1832 | /* Disable logging to console */ |
1833 | case SYSLOG_ACTION_CONSOLE_OFF: | |
a39d4a85 | 1834 | if (saved_console_loglevel == LOGLEVEL_DEFAULT) |
1aaad49e | 1835 | saved_console_loglevel = console_loglevel; |
1da177e4 LT |
1836 | console_loglevel = minimum_console_loglevel; |
1837 | break; | |
d78ca3cd KC |
1838 | /* Enable logging to console */ |
1839 | case SYSLOG_ACTION_CONSOLE_ON: | |
a39d4a85 | 1840 | if (saved_console_loglevel != LOGLEVEL_DEFAULT) { |
1aaad49e | 1841 | console_loglevel = saved_console_loglevel; |
a39d4a85 | 1842 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1aaad49e | 1843 | } |
1da177e4 | 1844 | break; |
d78ca3cd KC |
1845 | /* Set level of messages printed to console */ |
1846 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 | 1847 | if (len < 1 || len > 8) |
077a1cc0 | 1848 | return -EINVAL; |
1da177e4 LT |
1849 | if (len < minimum_console_loglevel) |
1850 | len = minimum_console_loglevel; | |
1851 | console_loglevel = len; | |
1aaad49e | 1852 | /* Implicitly re-enable logging to console */ |
a39d4a85 | 1853 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1da177e4 | 1854 | break; |
d78ca3cd KC |
1855 | /* Number of chars in the log buffer */ |
1856 | case SYSLOG_ACTION_SIZE_UNREAD: | |
b371cbb5 | 1857 | mutex_lock(&syslog_lock); |
13791c80 JO |
1858 | if (!prb_read_valid_info(prb, syslog_seq, &info, NULL)) { |
1859 | /* No unread messages. */ | |
b371cbb5 | 1860 | mutex_unlock(&syslog_lock); |
13791c80 JO |
1861 | return 0; |
1862 | } | |
1863 | if (info.seq != syslog_seq) { | |
7ff9554b | 1864 | /* messages are gone, move to first one */ |
13791c80 | 1865 | syslog_seq = info.seq; |
eb02dac9 | 1866 | syslog_partial = 0; |
7ff9554b | 1867 | } |
3ea4331c | 1868 | if (source == SYSLOG_FROM_PROC) { |
7ff9554b KS |
1869 | /* |
1870 | * Short-cut for poll(/"proc/kmsg") which simply checks | |
1871 | * for pending data, not the size; return the count of | |
1872 | * records, not the length. | |
1873 | */ | |
896fbe20 | 1874 | error = prb_next_seq(prb) - syslog_seq; |
7ff9554b | 1875 | } else { |
e80c1a9d | 1876 | bool time = syslog_partial ? syslog_time : printk_time; |
896fbe20 JO |
1877 | unsigned int line_count; |
1878 | u64 seq; | |
1879 | ||
1880 | prb_for_each_info(syslog_seq, prb, seq, &info, | |
1881 | &line_count) { | |
1882 | error += get_record_print_text_size(&info, line_count, | |
1883 | true, time); | |
e80c1a9d | 1884 | time = printk_time; |
7ff9554b | 1885 | } |
eb02dac9 | 1886 | error -= syslog_partial; |
7ff9554b | 1887 | } |
b371cbb5 | 1888 | mutex_unlock(&syslog_lock); |
1da177e4 | 1889 | break; |
d78ca3cd KC |
1890 | /* Size of the log buffer */ |
1891 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
1892 | error = log_buf_len; |
1893 | break; | |
1894 | default: | |
1895 | error = -EINVAL; | |
1896 | break; | |
1897 | } | |
077a1cc0 | 1898 | |
1da177e4 LT |
1899 | return error; |
1900 | } | |
1901 | ||
1e7bfb21 | 1902 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 1903 | { |
637241a9 | 1904 | return do_syslog(type, buf, len, SYSLOG_FROM_READER); |
1da177e4 LT |
1905 | } |
1906 | ||
c162d5b4 PM |
1907 | /* |
1908 | * Special console_lock variants that help to reduce the risk of soft-lockups. | |
1909 | * They allow to pass console_lock to another printk() call using a busy wait. | |
1910 | */ | |
1911 | ||
1912 | #ifdef CONFIG_LOCKDEP | |
1913 | static struct lockdep_map console_owner_dep_map = { | |
1914 | .name = "console_owner" | |
1915 | }; | |
1916 | #endif | |
1917 | ||
1918 | static DEFINE_RAW_SPINLOCK(console_owner_lock); | |
1919 | static struct task_struct *console_owner; | |
1920 | static bool console_waiter; | |
1921 | ||
1922 | /** | |
1923 | * console_lock_spinning_enable - mark beginning of code where another | |
1924 | * thread might safely busy wait | |
1925 | * | |
1926 | * This basically converts console_lock into a spinlock. This marks | |
1927 | * the section where the console_lock owner can not sleep, because | |
1928 | * there may be a waiter spinning (like a spinlock). Also it must be | |
1929 | * ready to hand over the lock at the end of the section. | |
1930 | */ | |
1931 | static void console_lock_spinning_enable(void) | |
1932 | { | |
1933 | raw_spin_lock(&console_owner_lock); | |
1934 | console_owner = current; | |
1935 | raw_spin_unlock(&console_owner_lock); | |
1936 | ||
1937 | /* The waiter may spin on us after setting console_owner */ | |
1938 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
1939 | } | |
1940 | ||
1941 | /** | |
1942 | * console_lock_spinning_disable_and_check - mark end of code where another | |
1943 | * thread was able to busy wait and check if there is a waiter | |
1944 | * | |
1945 | * This is called at the end of the section where spinning is allowed. | |
1946 | * It has two functions. First, it is a signal that it is no longer | |
1947 | * safe to start busy waiting for the lock. Second, it checks if | |
1948 | * there is a busy waiter and passes the lock rights to her. | |
1949 | * | |
1950 | * Important: Callers lose the lock if there was a busy waiter. | |
1951 | * They must not touch items synchronized by console_lock | |
1952 | * in this case. | |
1953 | * | |
1954 | * Return: 1 if the lock rights were passed, 0 otherwise. | |
1955 | */ | |
1956 | static int console_lock_spinning_disable_and_check(void) | |
1957 | { | |
1958 | int waiter; | |
1959 | ||
1960 | raw_spin_lock(&console_owner_lock); | |
1961 | waiter = READ_ONCE(console_waiter); | |
1962 | console_owner = NULL; | |
1963 | raw_spin_unlock(&console_owner_lock); | |
1964 | ||
1965 | if (!waiter) { | |
5facae4f | 1966 | spin_release(&console_owner_dep_map, _THIS_IP_); |
c162d5b4 PM |
1967 | return 0; |
1968 | } | |
1969 | ||
1970 | /* The waiter is now free to continue */ | |
1971 | WRITE_ONCE(console_waiter, false); | |
1972 | ||
5facae4f | 1973 | spin_release(&console_owner_dep_map, _THIS_IP_); |
c162d5b4 PM |
1974 | |
1975 | /* | |
1976 | * Hand off console_lock to waiter. The waiter will perform | |
1977 | * the up(). After this, the waiter is the console_lock owner. | |
1978 | */ | |
5facae4f | 1979 | mutex_release(&console_lock_dep_map, _THIS_IP_); |
c162d5b4 PM |
1980 | return 1; |
1981 | } | |
1982 | ||
1983 | /** | |
1984 | * console_trylock_spinning - try to get console_lock by busy waiting | |
1985 | * | |
1986 | * This allows to busy wait for the console_lock when the current | |
1987 | * owner is running in specially marked sections. It means that | |
1988 | * the current owner is running and cannot reschedule until it | |
1989 | * is ready to lose the lock. | |
1990 | * | |
1991 | * Return: 1 if we got the lock, 0 othrewise | |
1992 | */ | |
1993 | static int console_trylock_spinning(void) | |
1994 | { | |
1995 | struct task_struct *owner = NULL; | |
1996 | bool waiter; | |
1997 | bool spin = false; | |
1998 | unsigned long flags; | |
1999 | ||
2000 | if (console_trylock()) | |
2001 | return 1; | |
2002 | ||
d5150709 SB |
2003 | /* |
2004 | * It's unsafe to spin once a panic has begun. If we are the | |
2005 | * panic CPU, we may have already halted the owner of the | |
2006 | * console_sem. If we are not the panic CPU, then we should | |
2007 | * avoid taking console_sem, so the panic CPU has a better | |
2008 | * chance of cleanly acquiring it later. | |
2009 | */ | |
2010 | if (panic_in_progress()) | |
2011 | return 0; | |
2012 | ||
c162d5b4 PM |
2013 | printk_safe_enter_irqsave(flags); |
2014 | ||
2015 | raw_spin_lock(&console_owner_lock); | |
2016 | owner = READ_ONCE(console_owner); | |
2017 | waiter = READ_ONCE(console_waiter); | |
2018 | if (!waiter && owner && owner != current) { | |
2019 | WRITE_ONCE(console_waiter, true); | |
2020 | spin = true; | |
2021 | } | |
2022 | raw_spin_unlock(&console_owner_lock); | |
2023 | ||
2024 | /* | |
2025 | * If there is an active printk() writing to the | |
2026 | * consoles, instead of having it write our data too, | |
2027 | * see if we can offload that load from the active | |
2028 | * printer, and do some printing ourselves. | |
2029 | * Go into a spin only if there isn't already a waiter | |
2030 | * spinning, and there is an active printer, and | |
2031 | * that active printer isn't us (recursive printk?). | |
2032 | */ | |
2033 | if (!spin) { | |
2034 | printk_safe_exit_irqrestore(flags); | |
2035 | return 0; | |
2036 | } | |
2037 | ||
2038 | /* We spin waiting for the owner to release us */ | |
2039 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
2040 | /* Owner will clear console_waiter on hand off */ | |
2041 | while (READ_ONCE(console_waiter)) | |
2042 | cpu_relax(); | |
5facae4f | 2043 | spin_release(&console_owner_dep_map, _THIS_IP_); |
c162d5b4 PM |
2044 | |
2045 | printk_safe_exit_irqrestore(flags); | |
2046 | /* | |
2047 | * The owner passed the console lock to us. | |
2048 | * Since we did not spin on console lock, annotate | |
2049 | * this as a trylock. Otherwise lockdep will | |
2050 | * complain. | |
2051 | */ | |
2052 | mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_); | |
2053 | ||
2054 | return 1; | |
2055 | } | |
2056 | ||
1da177e4 | 2057 | /* |
a699449b | 2058 | * Call the specified console driver, asking it to write out the specified |
03a749e6 | 2059 | * text and length. If @dropped_text is non-NULL and any records have been |
a699449b | 2060 | * dropped, a dropped message will be written out first. |
1da177e4 | 2061 | */ |
03a749e6 JO |
2062 | static void call_console_driver(struct console *con, const char *text, size_t len, |
2063 | char *dropped_text) | |
1da177e4 | 2064 | { |
a699449b | 2065 | size_t dropped_len; |
1da177e4 | 2066 | |
03a749e6 JO |
2067 | if (con->dropped && dropped_text) { |
2068 | dropped_len = snprintf(dropped_text, DROPPED_TEXT_MAX, | |
896fbe20 | 2069 | "** %lu printk messages dropped **\n", |
a699449b JO |
2070 | con->dropped); |
2071 | con->dropped = 0; | |
2072 | con->write(con, dropped_text, dropped_len); | |
896fbe20 JO |
2073 | } |
2074 | ||
a699449b | 2075 | con->write(con, text, len); |
1da177e4 LT |
2076 | } |
2077 | ||
002eb6ad JO |
2078 | /* |
2079 | * Recursion is tracked separately on each CPU. If NMIs are supported, an | |
2080 | * additional NMI context per CPU is also separately tracked. Until per-CPU | |
2081 | * is available, a separate "early tracking" is performed. | |
2082 | */ | |
2083 | static DEFINE_PER_CPU(u8, printk_count); | |
2084 | static u8 printk_count_early; | |
2085 | #ifdef CONFIG_HAVE_NMI | |
2086 | static DEFINE_PER_CPU(u8, printk_count_nmi); | |
2087 | static u8 printk_count_nmi_early; | |
2088 | #endif | |
2089 | ||
2090 | /* | |
2091 | * Recursion is limited to keep the output sane. printk() should not require | |
2092 | * more than 1 level of recursion (allowing, for example, printk() to trigger | |
2093 | * a WARN), but a higher value is used in case some printk-internal errors | |
2094 | * exist, such as the ringbuffer validation checks failing. | |
2095 | */ | |
2096 | #define PRINTK_MAX_RECURSION 3 | |
2097 | ||
2098 | /* | |
2099 | * Return a pointer to the dedicated counter for the CPU+context of the | |
2100 | * caller. | |
2101 | */ | |
2102 | static u8 *__printk_recursion_counter(void) | |
2103 | { | |
2104 | #ifdef CONFIG_HAVE_NMI | |
2105 | if (in_nmi()) { | |
2106 | if (printk_percpu_data_ready()) | |
2107 | return this_cpu_ptr(&printk_count_nmi); | |
2108 | return &printk_count_nmi_early; | |
2109 | } | |
2110 | #endif | |
2111 | if (printk_percpu_data_ready()) | |
2112 | return this_cpu_ptr(&printk_count); | |
2113 | return &printk_count_early; | |
2114 | } | |
2115 | ||
2116 | /* | |
2117 | * Enter recursion tracking. Interrupts are disabled to simplify tracking. | |
2118 | * The caller must check the boolean return value to see if the recursion is | |
2119 | * allowed. On failure, interrupts are not disabled. | |
2120 | * | |
2121 | * @recursion_ptr must be a variable of type (u8 *) and is the same variable | |
2122 | * that is passed to printk_exit_irqrestore(). | |
2123 | */ | |
2124 | #define printk_enter_irqsave(recursion_ptr, flags) \ | |
2125 | ({ \ | |
2126 | bool success = true; \ | |
2127 | \ | |
2128 | typecheck(u8 *, recursion_ptr); \ | |
2129 | local_irq_save(flags); \ | |
2130 | (recursion_ptr) = __printk_recursion_counter(); \ | |
2131 | if (*(recursion_ptr) > PRINTK_MAX_RECURSION) { \ | |
2132 | local_irq_restore(flags); \ | |
2133 | success = false; \ | |
2134 | } else { \ | |
2135 | (*(recursion_ptr))++; \ | |
2136 | } \ | |
2137 | success; \ | |
2138 | }) | |
2139 | ||
2140 | /* Exit recursion tracking, restoring interrupts. */ | |
2141 | #define printk_exit_irqrestore(recursion_ptr, flags) \ | |
2142 | do { \ | |
2143 | typecheck(u8 *, recursion_ptr); \ | |
2144 | (*(recursion_ptr))--; \ | |
2145 | local_irq_restore(flags); \ | |
2146 | } while (0) | |
2147 | ||
af91322e DY |
2148 | int printk_delay_msec __read_mostly; |
2149 | ||
1f47e8af | 2150 | static inline void printk_delay(int level) |
af91322e | 2151 | { |
1f47e8af JO |
2152 | boot_delay_msec(level); |
2153 | ||
af91322e DY |
2154 | if (unlikely(printk_delay_msec)) { |
2155 | int m = printk_delay_msec; | |
2156 | ||
2157 | while (m--) { | |
2158 | mdelay(1); | |
2159 | touch_nmi_watchdog(); | |
2160 | } | |
2161 | } | |
2162 | } | |
2163 | ||
cbae05d3 TH |
2164 | static inline u32 printk_caller_id(void) |
2165 | { | |
2166 | return in_task() ? task_pid_nr(current) : | |
9f0844de | 2167 | 0x80000000 + smp_processor_id(); |
cbae05d3 TH |
2168 | } |
2169 | ||
b031a684 | 2170 | /** |
f3d75cf5 | 2171 | * printk_parse_prefix - Parse level and control flags. |
b031a684 JO |
2172 | * |
2173 | * @text: The terminated text message. | |
2174 | * @level: A pointer to the current level value, will be updated. | |
a1ad4b8a | 2175 | * @flags: A pointer to the current printk_info flags, will be updated. |
b031a684 JO |
2176 | * |
2177 | * @level may be NULL if the caller is not interested in the parsed value. | |
2178 | * Otherwise the variable pointed to by @level must be set to | |
2179 | * LOGLEVEL_DEFAULT in order to be updated with the parsed value. | |
2180 | * | |
a1ad4b8a CD |
2181 | * @flags may be NULL if the caller is not interested in the parsed value. |
2182 | * Otherwise the variable pointed to by @flags will be OR'd with the parsed | |
b031a684 JO |
2183 | * value. |
2184 | * | |
2185 | * Return: The length of the parsed level and control flags. | |
2186 | */ | |
f3d75cf5 | 2187 | u16 printk_parse_prefix(const char *text, int *level, |
a1ad4b8a | 2188 | enum printk_info_flags *flags) |
c362c7ff | 2189 | { |
b031a684 JO |
2190 | u16 prefix_len = 0; |
2191 | int kern_level; | |
cbae05d3 | 2192 | |
b031a684 JO |
2193 | while (*text) { |
2194 | kern_level = printk_get_level(text); | |
2195 | if (!kern_level) | |
2196 | break; | |
f5f022e5 | 2197 | |
b031a684 JO |
2198 | switch (kern_level) { |
2199 | case '0' ... '7': | |
2200 | if (level && *level == LOGLEVEL_DEFAULT) | |
2201 | *level = kern_level - '0'; | |
2202 | break; | |
2203 | case 'c': /* KERN_CONT */ | |
a1ad4b8a CD |
2204 | if (flags) |
2205 | *flags |= LOG_CONT; | |
b031a684 JO |
2206 | } |
2207 | ||
2208 | prefix_len += 2; | |
2209 | text += 2; | |
2210 | } | |
2211 | ||
2212 | return prefix_len; | |
2213 | } | |
2214 | ||
264a7504 | 2215 | __printf(5, 0) |
a1ad4b8a CD |
2216 | static u16 printk_sprint(char *text, u16 size, int facility, |
2217 | enum printk_info_flags *flags, const char *fmt, | |
2218 | va_list args) | |
b031a684 JO |
2219 | { |
2220 | u16 text_len; | |
2221 | ||
2222 | text_len = vscnprintf(text, size, fmt, args); | |
2223 | ||
2224 | /* Mark and strip a trailing newline. */ | |
2225 | if (text_len && text[text_len - 1] == '\n') { | |
2226 | text_len--; | |
a1ad4b8a | 2227 | *flags |= LOG_NEWLINE; |
b031a684 JO |
2228 | } |
2229 | ||
2230 | /* Strip log level and control flags. */ | |
2231 | if (facility == 0) { | |
2232 | u16 prefix_len; | |
2233 | ||
f3d75cf5 | 2234 | prefix_len = printk_parse_prefix(text, NULL, NULL); |
b031a684 JO |
2235 | if (prefix_len) { |
2236 | text_len -= prefix_len; | |
2237 | memmove(text, text + prefix_len, text_len); | |
f5f022e5 | 2238 | } |
c362c7ff LT |
2239 | } |
2240 | ||
701850dc ME |
2241 | trace_console_rcuidle(text, text_len); |
2242 | ||
b031a684 | 2243 | return text_len; |
c362c7ff LT |
2244 | } |
2245 | ||
b031a684 | 2246 | __printf(4, 0) |
ba552399 | 2247 | int vprintk_store(int facility, int level, |
74caba7f | 2248 | const struct dev_printk_info *dev_info, |
ba552399 | 2249 | const char *fmt, va_list args) |
1da177e4 | 2250 | { |
6b916706 | 2251 | struct prb_reserved_entry e; |
a1ad4b8a | 2252 | enum printk_info_flags flags = 0; |
6b916706 | 2253 | struct printk_record r; |
002eb6ad | 2254 | unsigned long irqflags; |
6b916706 | 2255 | u16 trunc_msg_len = 0; |
b031a684 | 2256 | char prefix_buf[8]; |
002eb6ad | 2257 | u8 *recursion_ptr; |
b031a684 JO |
2258 | u16 reserve_size; |
2259 | va_list args2; | |
9f0844de | 2260 | u32 caller_id; |
6b916706 | 2261 | u16 text_len; |
002eb6ad | 2262 | int ret = 0; |
6b916706 | 2263 | u64 ts_nsec; |
bfe8df3d | 2264 | |
9f0844de JO |
2265 | if (!printk_enter_irqsave(recursion_ptr, irqflags)) |
2266 | return 0; | |
2267 | ||
7ff9554b | 2268 | /* |
6b916706 JO |
2269 | * Since the duration of printk() can vary depending on the message |
2270 | * and state of the ringbuffer, grab the timestamp now so that it is | |
2271 | * close to the call of printk(). This provides a more deterministic | |
2272 | * timestamp with respect to the caller. | |
7ff9554b | 2273 | */ |
6b916706 | 2274 | ts_nsec = local_clock(); |
5fd29d6c | 2275 | |
9f0844de | 2276 | caller_id = printk_caller_id(); |
002eb6ad | 2277 | |
7ff9554b | 2278 | /* |
b031a684 JO |
2279 | * The sprintf needs to come first since the syslog prefix might be |
2280 | * passed in as a parameter. An extra byte must be reserved so that | |
2281 | * later the vscnprintf() into the reserved buffer has room for the | |
2282 | * terminating '\0', which is not counted by vsnprintf(). | |
7ff9554b | 2283 | */ |
b031a684 JO |
2284 | va_copy(args2, args); |
2285 | reserve_size = vsnprintf(&prefix_buf[0], sizeof(prefix_buf), fmt, args2) + 1; | |
2286 | va_end(args2); | |
9d90c8d9 | 2287 | |
b031a684 JO |
2288 | if (reserve_size > LOG_LINE_MAX) |
2289 | reserve_size = LOG_LINE_MAX; | |
088a52aa | 2290 | |
b031a684 JO |
2291 | /* Extract log level or control flags. */ |
2292 | if (facility == 0) | |
f3d75cf5 | 2293 | printk_parse_prefix(&prefix_buf[0], &level, &flags); |
5fd29d6c | 2294 | |
a39d4a85 | 2295 | if (level == LOGLEVEL_DEFAULT) |
c313af14 | 2296 | level = default_message_loglevel; |
9d90c8d9 | 2297 | |
74caba7f | 2298 | if (dev_info) |
a1ad4b8a | 2299 | flags |= LOG_NEWLINE; |
9d90c8d9 | 2300 | |
a1ad4b8a | 2301 | if (flags & LOG_CONT) { |
b031a684 | 2302 | prb_rec_init_wr(&r, reserve_size); |
6b916706 | 2303 | if (prb_reserve_in_last(&e, prb, &r, caller_id, LOG_LINE_MAX)) { |
b031a684 | 2304 | text_len = printk_sprint(&r.text_buf[r.info->text_len], reserve_size, |
a1ad4b8a | 2305 | facility, &flags, fmt, args); |
6b916706 | 2306 | r.info->text_len += text_len; |
088a52aa | 2307 | |
a1ad4b8a | 2308 | if (flags & LOG_NEWLINE) { |
6b916706 JO |
2309 | r.info->flags |= LOG_NEWLINE; |
2310 | prb_final_commit(&e); | |
2311 | } else { | |
2312 | prb_commit(&e); | |
088a52aa | 2313 | } |
4bcc595c | 2314 | |
002eb6ad JO |
2315 | ret = text_len; |
2316 | goto out; | |
5fd29d6c LT |
2317 | } |
2318 | } | |
2319 | ||
6b916706 JO |
2320 | /* |
2321 | * Explicitly initialize the record before every prb_reserve() call. | |
2322 | * prb_reserve_in_last() and prb_reserve() purposely invalidate the | |
2323 | * structure when they fail. | |
2324 | */ | |
b031a684 | 2325 | prb_rec_init_wr(&r, reserve_size); |
6b916706 JO |
2326 | if (!prb_reserve(&e, prb, &r)) { |
2327 | /* truncate the message if it is too long for empty buffer */ | |
b031a684 | 2328 | truncate_msg(&reserve_size, &trunc_msg_len); |
9d90c8d9 | 2329 | |
b031a684 | 2330 | prb_rec_init_wr(&r, reserve_size + trunc_msg_len); |
6b916706 | 2331 | if (!prb_reserve(&e, prb, &r)) |
002eb6ad | 2332 | goto out; |
6b916706 JO |
2333 | } |
2334 | ||
2335 | /* fill message */ | |
a1ad4b8a | 2336 | text_len = printk_sprint(&r.text_buf[0], reserve_size, facility, &flags, fmt, args); |
6b916706 JO |
2337 | if (trunc_msg_len) |
2338 | memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len); | |
2339 | r.info->text_len = text_len + trunc_msg_len; | |
2340 | r.info->facility = facility; | |
2341 | r.info->level = level & 7; | |
a1ad4b8a | 2342 | r.info->flags = flags & 0x1f; |
6b916706 JO |
2343 | r.info->ts_nsec = ts_nsec; |
2344 | r.info->caller_id = caller_id; | |
74caba7f | 2345 | if (dev_info) |
6b916706 | 2346 | memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info)); |
ac60ad74 | 2347 | |
6b916706 | 2348 | /* A message without a trailing newline can be continued. */ |
a1ad4b8a | 2349 | if (!(flags & LOG_NEWLINE)) |
6b916706 JO |
2350 | prb_commit(&e); |
2351 | else | |
2352 | prb_final_commit(&e); | |
2353 | ||
002eb6ad JO |
2354 | ret = text_len + trunc_msg_len; |
2355 | out: | |
2356 | printk_exit_irqrestore(recursion_ptr, irqflags); | |
2357 | return ret; | |
ba552399 | 2358 | } |
1da177e4 | 2359 | |
ba552399 | 2360 | asmlinkage int vprintk_emit(int facility, int level, |
74caba7f | 2361 | const struct dev_printk_info *dev_info, |
ba552399 PM |
2362 | const char *fmt, va_list args) |
2363 | { | |
2364 | int printed_len; | |
8749efc0 | 2365 | bool in_sched = false; |
ba552399 | 2366 | |
c39ea0b9 FT |
2367 | /* Suppress unimportant messages after panic happens */ |
2368 | if (unlikely(suppress_printk)) | |
2369 | return 0; | |
2370 | ||
13fb0f74 SB |
2371 | if (unlikely(suppress_panic_printk) && |
2372 | atomic_read(&panic_cpu) != raw_smp_processor_id()) | |
2373 | return 0; | |
2374 | ||
ba552399 PM |
2375 | if (level == LOGLEVEL_SCHED) { |
2376 | level = LOGLEVEL_DEFAULT; | |
2377 | in_sched = true; | |
2378 | } | |
2379 | ||
1f47e8af | 2380 | printk_delay(level); |
ba552399 | 2381 | |
74caba7f | 2382 | printed_len = vprintk_store(facility, level, dev_info, fmt, args); |
939f04be | 2383 | |
458df9fd | 2384 | /* If called from the scheduler, we can not call up(). */ |
09c5ba0a | 2385 | if (!in_sched && allow_direct_printing()) { |
fd5f7cde | 2386 | /* |
a699449b | 2387 | * The caller may be holding system-critical or |
09c5ba0a | 2388 | * timing-sensitive locks. Disable preemption during direct |
a699449b JO |
2389 | * printing of all remaining records to all consoles so that |
2390 | * this context can return as soon as possible. Hopefully | |
2391 | * another printk() caller will take over the printing. | |
fd5f7cde SS |
2392 | */ |
2393 | preempt_disable(); | |
d18bbc21 AM |
2394 | /* |
2395 | * Try to acquire and then immediately release the console | |
a699449b JO |
2396 | * semaphore. The release will print out buffers. With the |
2397 | * spinning variant, this context tries to take over the | |
2398 | * printing from another printing context. | |
d18bbc21 | 2399 | */ |
c162d5b4 | 2400 | if (console_trylock_spinning()) |
d18bbc21 | 2401 | console_unlock(); |
fd5f7cde | 2402 | preempt_enable(); |
d18bbc21 | 2403 | } |
76a8ad29 | 2404 | |
8749efc0 | 2405 | wake_up_klogd(); |
1da177e4 LT |
2406 | return printed_len; |
2407 | } | |
7ff9554b KS |
2408 | EXPORT_SYMBOL(vprintk_emit); |
2409 | ||
a0cba217 | 2410 | int vprintk_default(const char *fmt, va_list args) |
afdc34a3 | 2411 | { |
74caba7f | 2412 | return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, fmt, args); |
afdc34a3 SRRH |
2413 | } |
2414 | EXPORT_SYMBOL_GPL(vprintk_default); | |
2415 | ||
33701557 | 2416 | asmlinkage __visible int _printk(const char *fmt, ...) |
7ff9554b KS |
2417 | { |
2418 | va_list args; | |
2419 | int r; | |
2420 | ||
7ff9554b | 2421 | va_start(args, fmt); |
28e1745b | 2422 | r = vprintk(fmt, args); |
7ff9554b KS |
2423 | va_end(args); |
2424 | ||
2425 | return r; | |
2426 | } | |
33701557 | 2427 | EXPORT_SYMBOL(_printk); |
7f3a781d | 2428 | |
3b604ca8 JO |
2429 | static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress); |
2430 | ||
09c5ba0a JO |
2431 | static void printk_start_kthread(struct console *con); |
2432 | ||
96efedf1 | 2433 | #else /* CONFIG_PRINTK */ |
d59745ce | 2434 | |
cf5b0208 | 2435 | #define CONSOLE_LOG_MAX 0 |
03a749e6 | 2436 | #define DROPPED_TEXT_MAX 0 |
e80c1a9d | 2437 | #define printk_time false |
249771b8 | 2438 | |
896fbe20 JO |
2439 | #define prb_read_valid(rb, seq, r) false |
2440 | #define prb_first_valid_seq(rb) 0 | |
a699449b | 2441 | #define prb_next_seq(rb) 0 |
896fbe20 | 2442 | |
96efedf1 | 2443 | static u64 syslog_seq; |
896fbe20 JO |
2444 | |
2445 | static size_t record_print_text(const struct printk_record *r, | |
2446 | bool syslog, bool time) | |
2447 | { | |
2448 | return 0; | |
2449 | } | |
2450 | static ssize_t info_print_ext_header(char *buf, size_t size, | |
2451 | struct printk_info *info) | |
2452 | { | |
2453 | return 0; | |
2454 | } | |
6fe29354 | 2455 | static ssize_t msg_print_ext_body(char *buf, size_t size, |
74caba7f JO |
2456 | char *text, size_t text_len, |
2457 | struct dev_printk_info *dev_info) { return 0; } | |
c162d5b4 PM |
2458 | static void console_lock_spinning_enable(void) { } |
2459 | static int console_lock_spinning_disable_and_check(void) { return 0; } | |
03a749e6 JO |
2460 | static void call_console_driver(struct console *con, const char *text, size_t len, |
2461 | char *dropped_text) | |
2462 | { | |
2463 | } | |
a6ae928c | 2464 | static bool suppress_message_printing(int level) { return false; } |
3b604ca8 | 2465 | static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) { return true; } |
09c5ba0a JO |
2466 | static void printk_start_kthread(struct console *con) { } |
2467 | static bool allow_direct_printing(void) { return true; } | |
d59745ce | 2468 | |
7f3a781d | 2469 | #endif /* CONFIG_PRINTK */ |
d59745ce | 2470 | |
d0380e6c TG |
2471 | #ifdef CONFIG_EARLY_PRINTK |
2472 | struct console *early_console; | |
2473 | ||
722a9f92 | 2474 | asmlinkage __visible void early_printk(const char *fmt, ...) |
d0380e6c TG |
2475 | { |
2476 | va_list ap; | |
1dc6244b JP |
2477 | char buf[512]; |
2478 | int n; | |
2479 | ||
2480 | if (!early_console) | |
2481 | return; | |
d0380e6c TG |
2482 | |
2483 | va_start(ap, fmt); | |
1dc6244b | 2484 | n = vscnprintf(buf, sizeof(buf), fmt, ap); |
d0380e6c | 2485 | va_end(ap); |
1dc6244b JP |
2486 | |
2487 | early_console->write(early_console, buf, n); | |
d0380e6c TG |
2488 | } |
2489 | #endif | |
2490 | ||
a5a763b2 AK |
2491 | static void set_user_specified(struct console_cmdline *c, bool user_specified) |
2492 | { | |
2493 | if (!user_specified) | |
2494 | return; | |
2495 | ||
2496 | /* | |
2497 | * @c console was defined by the user on the command line. | |
2498 | * Do not clear when added twice also by SPCR or the device tree. | |
2499 | */ | |
2500 | c->user_specified = true; | |
2501 | /* At least one console defined by the user on the command line. */ | |
2502 | console_set_on_cmdline = 1; | |
2503 | } | |
2504 | ||
f7511d5f | 2505 | static int __add_preferred_console(char *name, int idx, char *options, |
e369d822 | 2506 | char *brl_options, bool user_specified) |
f7511d5f ST |
2507 | { |
2508 | struct console_cmdline *c; | |
2509 | int i; | |
2510 | ||
2511 | /* | |
2512 | * See if this tty is not yet registered, and | |
2513 | * if we have a slot free. | |
2514 | */ | |
dac8bbba PM |
2515 | for (i = 0, c = console_cmdline; |
2516 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2517 | i++, c++) { | |
23475408 | 2518 | if (strcmp(c->name, name) == 0 && c->index == idx) { |
dac8bbba PM |
2519 | if (!brl_options) |
2520 | preferred_console = i; | |
a5a763b2 | 2521 | set_user_specified(c, user_specified); |
23475408 | 2522 | return 0; |
f7511d5f | 2523 | } |
23475408 | 2524 | } |
f7511d5f ST |
2525 | if (i == MAX_CMDLINECONSOLES) |
2526 | return -E2BIG; | |
2527 | if (!brl_options) | |
ad86ee2b | 2528 | preferred_console = i; |
f7511d5f ST |
2529 | strlcpy(c->name, name, sizeof(c->name)); |
2530 | c->options = options; | |
a5a763b2 | 2531 | set_user_specified(c, user_specified); |
bbeddf52 JP |
2532 | braille_set_options(c, brl_options); |
2533 | ||
f7511d5f ST |
2534 | c->index = idx; |
2535 | return 0; | |
2536 | } | |
cca10d58 SS |
2537 | |
2538 | static int __init console_msg_format_setup(char *str) | |
2539 | { | |
2540 | if (!strcmp(str, "syslog")) | |
2541 | console_msg_format = MSG_FORMAT_SYSLOG; | |
2542 | if (!strcmp(str, "default")) | |
2543 | console_msg_format = MSG_FORMAT_DEFAULT; | |
2544 | return 1; | |
2545 | } | |
2546 | __setup("console_msg_format=", console_msg_format_setup); | |
2547 | ||
2ea1c539 | 2548 | /* |
0b90fec3 AE |
2549 | * Set up a console. Called via do_early_param() in init/main.c |
2550 | * for each "console=" parameter in the boot command line. | |
2ea1c539 JB |
2551 | */ |
2552 | static int __init console_setup(char *str) | |
2553 | { | |
0b90fec3 | 2554 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ |
f7511d5f | 2555 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
2556 | int idx; |
2557 | ||
3cffa06a PM |
2558 | /* |
2559 | * console="" or console=null have been suggested as a way to | |
2560 | * disable console output. Use ttynull that has been created | |
acebb559 | 2561 | * for exactly this purpose. |
3cffa06a PM |
2562 | */ |
2563 | if (str[0] == 0 || strcmp(str, "null") == 0) { | |
2564 | __add_preferred_console("ttynull", 0, NULL, NULL, true); | |
48021f98 | 2565 | return 1; |
3cffa06a | 2566 | } |
48021f98 | 2567 | |
bbeddf52 JP |
2568 | if (_braille_console_setup(&str, &brl_options)) |
2569 | return 1; | |
f7511d5f | 2570 | |
2ea1c539 JB |
2571 | /* |
2572 | * Decode str into name, index, options. | |
2573 | */ | |
2574 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
2575 | strcpy(buf, "ttyS"); |
2576 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 2577 | } else { |
eaa944af | 2578 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 2579 | } |
eaa944af | 2580 | buf[sizeof(buf) - 1] = 0; |
249771b8 AE |
2581 | options = strchr(str, ','); |
2582 | if (options) | |
2ea1c539 JB |
2583 | *(options++) = 0; |
2584 | #ifdef __sparc__ | |
2585 | if (!strcmp(str, "ttya")) | |
eaa944af | 2586 | strcpy(buf, "ttyS0"); |
2ea1c539 | 2587 | if (!strcmp(str, "ttyb")) |
eaa944af | 2588 | strcpy(buf, "ttyS1"); |
2ea1c539 | 2589 | #endif |
eaa944af | 2590 | for (s = buf; *s; s++) |
249771b8 | 2591 | if (isdigit(*s) || *s == ',') |
2ea1c539 JB |
2592 | break; |
2593 | idx = simple_strtoul(s, NULL, 10); | |
2594 | *s = 0; | |
2595 | ||
e369d822 | 2596 | __add_preferred_console(buf, idx, options, brl_options, true); |
2ea1c539 JB |
2597 | return 1; |
2598 | } | |
2599 | __setup("console=", console_setup); | |
2600 | ||
3c0547ba MM |
2601 | /** |
2602 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
2603 | * @name: device name |
2604 | * @idx: device index | |
2605 | * @options: options for this console | |
3c0547ba MM |
2606 | * |
2607 | * The last preferred console added will be used for kernel messages | |
2608 | * and stdin/out/err for init. Normally this is used by console_setup | |
2609 | * above to handle user-supplied console arguments; however it can also | |
2610 | * be used by arch-specific code either to override the user or more | |
2611 | * commonly to provide a default console (ie from PROM variables) when | |
2612 | * the user has not supplied one. | |
2613 | */ | |
fb445ee5 | 2614 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 2615 | { |
e369d822 | 2616 | return __add_preferred_console(name, idx, options, NULL, false); |
3c0547ba MM |
2617 | } |
2618 | ||
d25d9fec | 2619 | bool console_suspend_enabled = true; |
8f4ce8c3 AS |
2620 | EXPORT_SYMBOL(console_suspend_enabled); |
2621 | ||
2622 | static int __init console_suspend_disable(char *str) | |
2623 | { | |
d25d9fec | 2624 | console_suspend_enabled = false; |
8f4ce8c3 AS |
2625 | return 1; |
2626 | } | |
2627 | __setup("no_console_suspend", console_suspend_disable); | |
134620f7 YZ |
2628 | module_param_named(console_suspend, console_suspend_enabled, |
2629 | bool, S_IRUGO | S_IWUSR); | |
2630 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" | |
2631 | " and hibernate operations"); | |
8f4ce8c3 | 2632 | |
10102a89 DS |
2633 | static bool printk_console_no_auto_verbose; |
2634 | ||
2635 | void console_verbose(void) | |
2636 | { | |
2637 | if (console_loglevel && !printk_console_no_auto_verbose) | |
2638 | console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; | |
2639 | } | |
2640 | EXPORT_SYMBOL_GPL(console_verbose); | |
2641 | ||
2642 | module_param_named(console_no_auto_verbose, printk_console_no_auto_verbose, bool, 0644); | |
2643 | MODULE_PARM_DESC(console_no_auto_verbose, "Disable console loglevel raise to highest on oops/panic/etc"); | |
2644 | ||
557240b4 LT |
2645 | /** |
2646 | * suspend_console - suspend the console subsystem | |
2647 | * | |
2648 | * This disables printk() while we go into suspend states | |
2649 | */ | |
2650 | void suspend_console(void) | |
2651 | { | |
8f4ce8c3 AS |
2652 | if (!console_suspend_enabled) |
2653 | return; | |
47319f71 | 2654 | pr_info("Suspending console(s) (use no_console_suspend to debug)\n"); |
3b604ca8 | 2655 | pr_flush(1000, true); |
ac751efa | 2656 | console_lock(); |
557240b4 | 2657 | console_suspended = 1; |
bd8d7cf5 | 2658 | up_console_sem(); |
557240b4 LT |
2659 | } |
2660 | ||
2661 | void resume_console(void) | |
2662 | { | |
8f4ce8c3 AS |
2663 | if (!console_suspend_enabled) |
2664 | return; | |
bd8d7cf5 | 2665 | down_console_sem(); |
557240b4 | 2666 | console_suspended = 0; |
ac751efa | 2667 | console_unlock(); |
3b604ca8 | 2668 | pr_flush(1000, true); |
557240b4 LT |
2669 | } |
2670 | ||
034260d6 KC |
2671 | /** |
2672 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
90b14889 | 2673 | * @cpu: unused |
034260d6 KC |
2674 | * |
2675 | * If printk() is called from a CPU that is not online yet, the messages | |
64ca752d SS |
2676 | * will be printed on the console only if there are CON_ANYTIME consoles. |
2677 | * This function is called when a new CPU comes online (or fails to come | |
2678 | * up) or goes offline. | |
034260d6 | 2679 | */ |
90b14889 SAS |
2680 | static int console_cpu_notify(unsigned int cpu) |
2681 | { | |
f97960fb | 2682 | if (!cpuhp_tasks_frozen) { |
64ca752d SS |
2683 | /* If trylock fails, someone else is doing the printing */ |
2684 | if (console_trylock()) | |
2685 | console_unlock(); | |
8e274732 JO |
2686 | else { |
2687 | /* | |
2688 | * If a new CPU comes online, the conditions for | |
2689 | * printer_should_wake() may have changed for some | |
2690 | * kthread printer with !CON_ANYTIME. | |
2691 | */ | |
2692 | wake_up_klogd(); | |
2693 | } | |
034260d6 | 2694 | } |
90b14889 | 2695 | return 0; |
034260d6 KC |
2696 | } |
2697 | ||
1da177e4 | 2698 | /** |
ac751efa | 2699 | * console_lock - lock the console system for exclusive use. |
1da177e4 | 2700 | * |
ac751efa | 2701 | * Acquires a lock which guarantees that the caller has |
1da177e4 LT |
2702 | * exclusive access to the console system and the console_drivers list. |
2703 | * | |
2704 | * Can sleep, returns nothing. | |
2705 | */ | |
ac751efa | 2706 | void console_lock(void) |
1da177e4 | 2707 | { |
6b898c07 DV |
2708 | might_sleep(); |
2709 | ||
bd8d7cf5 | 2710 | down_console_sem(); |
403f3075 AH |
2711 | if (console_suspended) |
2712 | return; | |
8e274732 | 2713 | console_kthreads_block(); |
1da177e4 LT |
2714 | console_may_schedule = 1; |
2715 | } | |
ac751efa | 2716 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 2717 | |
ac751efa TH |
2718 | /** |
2719 | * console_trylock - try to lock the console system for exclusive use. | |
2720 | * | |
0b90fec3 AE |
2721 | * Try to acquire a lock which guarantees that the caller has exclusive |
2722 | * access to the console system and the console_drivers list. | |
ac751efa TH |
2723 | * |
2724 | * returns 1 on success, and 0 on failure to acquire the lock. | |
2725 | */ | |
2726 | int console_trylock(void) | |
1da177e4 | 2727 | { |
bd8d7cf5 | 2728 | if (down_trylock_console_sem()) |
ac751efa | 2729 | return 0; |
403f3075 | 2730 | if (console_suspended) { |
bd8d7cf5 | 2731 | up_console_sem(); |
ac751efa | 2732 | return 0; |
403f3075 | 2733 | } |
8e274732 JO |
2734 | if (!console_kthreads_atomic_tryblock()) { |
2735 | up_console_sem(); | |
2736 | return 0; | |
2737 | } | |
fd5f7cde | 2738 | console_may_schedule = 0; |
ac751efa | 2739 | return 1; |
1da177e4 | 2740 | } |
ac751efa | 2741 | EXPORT_SYMBOL(console_trylock); |
1da177e4 | 2742 | |
ab406816 JO |
2743 | /* |
2744 | * This is used to help to make sure that certain paths within the VT code are | |
2745 | * running with the console lock held. It is definitely not the perfect debug | |
2746 | * tool (it is not known if the VT code is the task holding the console lock), | |
2747 | * but it helps tracking those weird code paths in the console code such as | |
2748 | * when the console is suspended: where the console is not locked but no | |
2749 | * console printing may occur. | |
2750 | * | |
2751 | * Note: This returns true when the console is suspended but is not locked. | |
2752 | * This is intentional because the VT code must consider that situation | |
2753 | * the same as if the console was locked. | |
2754 | */ | |
1da177e4 LT |
2755 | int is_console_locked(void) |
2756 | { | |
ab406816 | 2757 | return (console_kthreads_blocked || atomic_read(&console_kthreads_active)); |
1da177e4 | 2758 | } |
d48de54a | 2759 | EXPORT_SYMBOL(is_console_locked); |
1da177e4 | 2760 | |
8ebc476f SB |
2761 | /* |
2762 | * Return true when this CPU should unlock console_sem without pushing all | |
2763 | * messages to the console. This reduces the chance that the console is | |
2764 | * locked when the panic CPU tries to use it. | |
2765 | */ | |
2766 | static bool abandon_console_lock_in_panic(void) | |
2767 | { | |
2768 | if (!panic_in_progress()) | |
2769 | return false; | |
2770 | ||
2771 | /* | |
2772 | * We can use raw_smp_processor_id() here because it is impossible for | |
2773 | * the task to be migrated to the panic_cpu, or away from it. If | |
2774 | * panic_cpu has already been set, and we're not currently executing on | |
2775 | * that CPU, then we never will be. | |
2776 | */ | |
2777 | return atomic_read(&panic_cpu) != raw_smp_processor_id(); | |
2778 | } | |
2779 | ||
09c5ba0a | 2780 | static inline bool __console_is_usable(short flags) |
a699449b | 2781 | { |
09c5ba0a | 2782 | if (!(flags & CON_ENABLED)) |
a699449b JO |
2783 | return false; |
2784 | ||
2785 | /* | |
2786 | * Console drivers may assume that per-cpu resources have been | |
2787 | * allocated. So unless they're explicitly marked as being able to | |
2788 | * cope (CON_ANYTIME) don't call them until this CPU is officially up. | |
2789 | */ | |
2790 | if (!cpu_online(raw_smp_processor_id()) && | |
09c5ba0a | 2791 | !(flags & CON_ANYTIME)) |
a699449b JO |
2792 | return false; |
2793 | ||
2794 | return true; | |
2795 | } | |
2796 | ||
09c5ba0a JO |
2797 | /* |
2798 | * Check if the given console is currently capable and allowed to print | |
2799 | * records. | |
2800 | * | |
8e274732 | 2801 | * Requires holding the console_lock. |
09c5ba0a JO |
2802 | */ |
2803 | static inline bool console_is_usable(struct console *con) | |
2804 | { | |
2805 | if (!con->write) | |
2806 | return false; | |
2807 | ||
2808 | return __console_is_usable(con->flags); | |
2809 | } | |
2810 | ||
a699449b JO |
2811 | static void __console_unlock(void) |
2812 | { | |
8e274732 JO |
2813 | /* |
2814 | * Depending on whether console_lock() or console_trylock() was used, | |
2815 | * appropriately allow the kthread printers to continue. | |
2816 | */ | |
2817 | if (console_kthreads_blocked) | |
2818 | console_kthreads_unblock(); | |
2819 | else | |
2820 | console_kthreads_atomic_unblock(); | |
2821 | ||
2822 | /* | |
2823 | * New records may have arrived while the console was locked. | |
2824 | * Wake the kthread printers to print them. | |
2825 | */ | |
2826 | wake_up_klogd(); | |
2827 | ||
a699449b JO |
2828 | up_console_sem(); |
2829 | } | |
2830 | ||
2831 | /* | |
2832 | * Print one record for the given console. The record printed is whatever | |
2833 | * record is the next available record for the given console. | |
2834 | * | |
03a749e6 JO |
2835 | * @text is a buffer of size CONSOLE_LOG_MAX. |
2836 | * | |
2837 | * If extended messages should be printed, @ext_text is a buffer of size | |
2838 | * CONSOLE_EXT_LOG_MAX. Otherwise @ext_text must be NULL. | |
2839 | * | |
2840 | * If dropped messages should be printed, @dropped_text is a buffer of size | |
2841 | * DROPPED_TEXT_MAX. Otherwise @dropped_text must be NULL. | |
2842 | * | |
a699449b JO |
2843 | * @handover will be set to true if a printk waiter has taken over the |
2844 | * console_lock, in which case the caller is no longer holding the | |
8e274732 JO |
2845 | * console_lock. Otherwise it is set to false. A NULL pointer may be provided |
2846 | * to disable allowing the console_lock to be taken over by a printk waiter. | |
a699449b JO |
2847 | * |
2848 | * Returns false if the given console has no next record to print, otherwise | |
2849 | * true. | |
a8199371 | 2850 | * |
8e274732 JO |
2851 | * Requires the console_lock if @handover is non-NULL. |
2852 | * Requires con->lock otherwise. | |
a8199371 | 2853 | */ |
8e274732 JO |
2854 | static bool __console_emit_next_record(struct console *con, char *text, char *ext_text, |
2855 | char *dropped_text, bool *handover) | |
a8199371 | 2856 | { |
8e274732 | 2857 | static atomic_t panic_console_dropped = ATOMIC_INIT(0); |
a699449b JO |
2858 | struct printk_info info; |
2859 | struct printk_record r; | |
2860 | unsigned long flags; | |
2861 | char *write_text; | |
2862 | size_t len; | |
2863 | ||
03a749e6 | 2864 | prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX); |
a699449b | 2865 | |
8e274732 JO |
2866 | if (handover) |
2867 | *handover = false; | |
a699449b JO |
2868 | |
2869 | if (!prb_read_valid(prb, con->seq, &r)) | |
2870 | return false; | |
2871 | ||
2872 | if (con->seq != r.info->seq) { | |
2873 | con->dropped += r.info->seq - con->seq; | |
2874 | con->seq = r.info->seq; | |
8e274732 JO |
2875 | if (panic_in_progress() && |
2876 | atomic_fetch_inc_relaxed(&panic_console_dropped) > 10) { | |
a699449b JO |
2877 | suppress_panic_printk = 1; |
2878 | pr_warn_once("Too many dropped messages. Suppress messages on non-panic CPUs to prevent livelock.\n"); | |
2879 | } | |
2880 | } | |
2881 | ||
2882 | /* Skip record that has level above the console loglevel. */ | |
2883 | if (suppress_message_printing(r.info->level)) { | |
2884 | con->seq++; | |
2885 | goto skip; | |
2886 | } | |
2887 | ||
03a749e6 JO |
2888 | if (ext_text) { |
2889 | write_text = ext_text; | |
2890 | len = info_print_ext_header(ext_text, CONSOLE_EXT_LOG_MAX, r.info); | |
2891 | len += msg_print_ext_body(ext_text + len, CONSOLE_EXT_LOG_MAX - len, | |
a699449b JO |
2892 | &r.text_buf[0], r.info->text_len, &r.info->dev_info); |
2893 | } else { | |
03a749e6 | 2894 | write_text = text; |
a699449b JO |
2895 | len = record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, printk_time); |
2896 | } | |
2897 | ||
8e274732 JO |
2898 | if (handover) { |
2899 | /* | |
2900 | * While actively printing out messages, if another printk() | |
2901 | * were to occur on another CPU, it may wait for this one to | |
2902 | * finish. This task can not be preempted if there is a | |
2903 | * waiter waiting to take over. | |
2904 | * | |
2905 | * Interrupts are disabled because the hand over to a waiter | |
2906 | * must not be interrupted until the hand over is completed | |
2907 | * (@console_waiter is cleared). | |
2908 | */ | |
2909 | printk_safe_enter_irqsave(flags); | |
2910 | console_lock_spinning_enable(); | |
2911 | ||
2912 | /* don't trace irqsoff print latency */ | |
2913 | stop_critical_timings(); | |
2914 | } | |
a699449b | 2915 | |
03a749e6 | 2916 | call_console_driver(con, write_text, len, dropped_text); |
a699449b JO |
2917 | |
2918 | con->seq++; | |
2919 | ||
8e274732 JO |
2920 | if (handover) { |
2921 | start_critical_timings(); | |
2922 | *handover = console_lock_spinning_disable_and_check(); | |
2923 | printk_safe_exit_irqrestore(flags); | |
2924 | } | |
a699449b JO |
2925 | skip: |
2926 | return true; | |
2927 | } | |
2928 | ||
8e274732 JO |
2929 | /* |
2930 | * Print a record for a given console, but allow another printk() caller to | |
2931 | * take over the console_lock and continue printing. | |
2932 | * | |
2933 | * Requires the console_lock, but depending on @handover after the call, the | |
2934 | * caller may no longer have the console_lock. | |
2935 | * | |
2936 | * See __console_emit_next_record() for argument and return details. | |
2937 | */ | |
2938 | static bool console_emit_next_record_transferable(struct console *con, char *text, char *ext_text, | |
2939 | char *dropped_text, bool *handover) | |
2940 | { | |
2941 | /* | |
2942 | * Handovers are only supported if threaded printers are atomically | |
2943 | * blocked. The context taking over the console_lock may be atomic. | |
2944 | */ | |
2945 | if (!console_kthreads_atomically_blocked()) { | |
2946 | *handover = false; | |
2947 | handover = NULL; | |
2948 | } | |
2949 | ||
2950 | return __console_emit_next_record(con, text, ext_text, dropped_text, handover); | |
2951 | } | |
2952 | ||
a699449b JO |
2953 | /* |
2954 | * Print out all remaining records to all consoles. | |
2955 | * | |
2956 | * @do_cond_resched is set by the caller. It can be true only in schedulable | |
2957 | * context. | |
2958 | * | |
2959 | * @next_seq is set to the sequence number after the last available record. | |
2960 | * The value is valid only when this function returns true. It means that all | |
2961 | * usable consoles are completely flushed. | |
2962 | * | |
2963 | * @handover will be set to true if a printk waiter has taken over the | |
2964 | * console_lock, in which case the caller is no longer holding the | |
2965 | * console_lock. Otherwise it is set to false. | |
2966 | * | |
2967 | * Returns true when there was at least one usable console and all messages | |
2968 | * were flushed to all usable consoles. A returned false informs the caller | |
2969 | * that everything was not flushed (either there were no usable consoles or | |
2970 | * another context has taken over printing or it is a panic situation and this | |
09c5ba0a JO |
2971 | * is not the panic CPU or direct printing is not preferred). Regardless the |
2972 | * reason, the caller should assume it is not useful to immediately try again. | |
a699449b JO |
2973 | * |
2974 | * Requires the console_lock. | |
2975 | */ | |
2976 | static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handover) | |
2977 | { | |
03a749e6 JO |
2978 | static char dropped_text[DROPPED_TEXT_MAX]; |
2979 | static char ext_text[CONSOLE_EXT_LOG_MAX]; | |
2980 | static char text[CONSOLE_LOG_MAX]; | |
a699449b JO |
2981 | bool any_usable = false; |
2982 | struct console *con; | |
2983 | bool any_progress; | |
2984 | ||
2985 | *next_seq = 0; | |
2986 | *handover = false; | |
2987 | ||
2988 | do { | |
09c5ba0a JO |
2989 | /* Let the kthread printers do the work if they can. */ |
2990 | if (!allow_direct_printing()) | |
2991 | return false; | |
2992 | ||
a699449b JO |
2993 | any_progress = false; |
2994 | ||
2995 | for_each_console(con) { | |
2996 | bool progress; | |
2997 | ||
2998 | if (!console_is_usable(con)) | |
2999 | continue; | |
3000 | any_usable = true; | |
3001 | ||
03a749e6 JO |
3002 | if (con->flags & CON_EXTENDED) { |
3003 | /* Extended consoles do not print "dropped messages". */ | |
8e274732 JO |
3004 | progress = console_emit_next_record_transferable(con, &text[0], |
3005 | &ext_text[0], NULL, handover); | |
03a749e6 | 3006 | } else { |
8e274732 JO |
3007 | progress = console_emit_next_record_transferable(con, &text[0], |
3008 | NULL, &dropped_text[0], handover); | |
03a749e6 | 3009 | } |
a699449b JO |
3010 | if (*handover) |
3011 | return false; | |
3012 | ||
3013 | /* Track the next of the highest seq flushed. */ | |
3014 | if (con->seq > *next_seq) | |
3015 | *next_seq = con->seq; | |
3016 | ||
3017 | if (!progress) | |
3018 | continue; | |
3019 | any_progress = true; | |
3020 | ||
3021 | /* Allow panic_cpu to take over the consoles safely. */ | |
3022 | if (abandon_console_lock_in_panic()) | |
3023 | return false; | |
3024 | ||
3025 | if (do_cond_resched) | |
3026 | cond_resched(); | |
3027 | } | |
3028 | } while (any_progress); | |
3029 | ||
3030 | return any_usable; | |
a8199371 SS |
3031 | } |
3032 | ||
1da177e4 | 3033 | /** |
ac751efa | 3034 | * console_unlock - unlock the console system |
1da177e4 | 3035 | * |
ac751efa | 3036 | * Releases the console_lock which the caller holds on the console system |
1da177e4 LT |
3037 | * and the console driver list. |
3038 | * | |
ac751efa TH |
3039 | * While the console_lock was held, console output may have been buffered |
3040 | * by printk(). If this is the case, console_unlock(); emits | |
3041 | * the output prior to releasing the lock. | |
1da177e4 | 3042 | * |
ac751efa | 3043 | * console_unlock(); may be called from any context. |
1da177e4 | 3044 | */ |
ac751efa | 3045 | void console_unlock(void) |
1da177e4 | 3046 | { |
a699449b JO |
3047 | bool do_cond_resched; |
3048 | bool handover; | |
3049 | bool flushed; | |
3050 | u64 next_seq; | |
1da177e4 | 3051 | |
557240b4 | 3052 | if (console_suspended) { |
bd8d7cf5 | 3053 | up_console_sem(); |
557240b4 LT |
3054 | return; |
3055 | } | |
78944e54 | 3056 | |
8d91f8b1 | 3057 | /* |
257ab443 | 3058 | * Console drivers are called with interrupts disabled, so |
8d91f8b1 TH |
3059 | * @console_may_schedule should be cleared before; however, we may |
3060 | * end up dumping a lot of lines, for example, if called from | |
3061 | * console registration path, and should invoke cond_resched() | |
3062 | * between lines if allowable. Not doing so can cause a very long | |
3063 | * scheduling stall on a slow console leading to RCU stall and | |
3064 | * softlockup warnings which exacerbate the issue with more | |
a699449b JO |
3065 | * messages practically incapacitating the system. Therefore, create |
3066 | * a local to use for the printing loop. | |
8d91f8b1 TH |
3067 | */ |
3068 | do_cond_resched = console_may_schedule; | |
78944e54 | 3069 | |
a699449b JO |
3070 | do { |
3071 | console_may_schedule = 0; | |
649e6ee3 | 3072 | |
a699449b JO |
3073 | flushed = console_flush_all(do_cond_resched, &next_seq, &handover); |
3074 | if (!handover) | |
3075 | __console_unlock(); | |
f92b070f | 3076 | |
896fbe20 | 3077 | /* |
a699449b JO |
3078 | * Abort if there was a failure to flush all messages to all |
3079 | * usable consoles. Either it is not possible to flush (in | |
3080 | * which case it would be an infinite loop of retrying) or | |
3081 | * another context has taken over printing. | |
896fbe20 | 3082 | */ |
a699449b JO |
3083 | if (!flushed) |
3084 | break; | |
7ff9554b | 3085 | |
dbdda842 | 3086 | /* |
a699449b JO |
3087 | * Some context may have added new records after |
3088 | * console_flush_all() but before unlocking the console. | |
3089 | * Re-check if there is a new record to flush. If the trylock | |
3090 | * fails, another context is already handling the printing. | |
dbdda842 | 3091 | */ |
a699449b | 3092 | } while (prb_read_valid(prb, next_seq, NULL) && console_trylock()); |
1da177e4 | 3093 | } |
ac751efa | 3094 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 3095 | |
ddad86c2 MW |
3096 | /** |
3097 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
3098 | * |
3099 | * If the console code is currently allowed to sleep, and | |
3100 | * if this CPU should yield the CPU to another task, do | |
3101 | * so here. | |
3102 | * | |
ac751efa | 3103 | * Must be called within console_lock();. |
1da177e4 LT |
3104 | */ |
3105 | void __sched console_conditional_schedule(void) | |
3106 | { | |
3107 | if (console_may_schedule) | |
3108 | cond_resched(); | |
3109 | } | |
3110 | EXPORT_SYMBOL(console_conditional_schedule); | |
3111 | ||
1da177e4 LT |
3112 | void console_unblank(void) |
3113 | { | |
3114 | struct console *c; | |
3115 | ||
3116 | /* | |
3117 | * console_unblank can no longer be called in interrupt context unless | |
3118 | * oops_in_progress is set to 1.. | |
3119 | */ | |
3120 | if (oops_in_progress) { | |
bd8d7cf5 | 3121 | if (down_trylock_console_sem() != 0) |
1da177e4 | 3122 | return; |
8e274732 JO |
3123 | if (!console_kthreads_atomic_tryblock()) { |
3124 | up_console_sem(); | |
3125 | return; | |
3126 | } | |
1da177e4 | 3127 | } else |
ac751efa | 3128 | console_lock(); |
1da177e4 | 3129 | |
1da177e4 | 3130 | console_may_schedule = 0; |
4d091611 | 3131 | for_each_console(c) |
1da177e4 LT |
3132 | if ((c->flags & CON_ENABLED) && c->unblank) |
3133 | c->unblank(); | |
ac751efa | 3134 | console_unlock(); |
3b604ca8 JO |
3135 | |
3136 | if (!oops_in_progress) | |
3137 | pr_flush(1000, true); | |
1da177e4 | 3138 | } |
1da177e4 | 3139 | |
8d91f8b1 TH |
3140 | /** |
3141 | * console_flush_on_panic - flush console content on panic | |
de6da1e8 | 3142 | * @mode: flush all messages in buffer or just the pending ones |
8d91f8b1 TH |
3143 | * |
3144 | * Immediately output all pending messages no matter what. | |
3145 | */ | |
de6da1e8 | 3146 | void console_flush_on_panic(enum con_flush_mode mode) |
8d91f8b1 TH |
3147 | { |
3148 | /* | |
3149 | * If someone else is holding the console lock, trylock will fail | |
3150 | * and may_schedule may be set. Ignore and proceed to unlock so | |
3151 | * that messages are flushed out. As this can be called from any | |
3152 | * context and we don't want to get preempted while flushing, | |
3153 | * ensure may_schedule is cleared. | |
3154 | */ | |
3155 | console_trylock(); | |
3156 | console_may_schedule = 0; | |
de6da1e8 | 3157 | |
a699449b JO |
3158 | if (mode == CONSOLE_REPLAY_ALL) { |
3159 | struct console *c; | |
3160 | u64 seq; | |
3161 | ||
3162 | seq = prb_first_valid_seq(prb); | |
3163 | for_each_console(c) | |
3164 | c->seq = seq; | |
3165 | } | |
8d91f8b1 TH |
3166 | console_unlock(); |
3167 | } | |
3168 | ||
1da177e4 LT |
3169 | /* |
3170 | * Return the console tty driver structure and its associated index | |
3171 | */ | |
3172 | struct tty_driver *console_device(int *index) | |
3173 | { | |
3174 | struct console *c; | |
3175 | struct tty_driver *driver = NULL; | |
3176 | ||
ac751efa | 3177 | console_lock(); |
4d091611 | 3178 | for_each_console(c) { |
1da177e4 LT |
3179 | if (!c->device) |
3180 | continue; | |
3181 | driver = c->device(c, index); | |
3182 | if (driver) | |
3183 | break; | |
3184 | } | |
ac751efa | 3185 | console_unlock(); |
1da177e4 LT |
3186 | return driver; |
3187 | } | |
3188 | ||
3189 | /* | |
3190 | * Prevent further output on the passed console device so that (for example) | |
3191 | * serial drivers can disable console output before suspending a port, and can | |
3192 | * re-enable output afterwards. | |
3193 | */ | |
3194 | void console_stop(struct console *console) | |
3195 | { | |
3b604ca8 | 3196 | __pr_flush(console, 1000, true); |
ac751efa | 3197 | console_lock(); |
1da177e4 | 3198 | console->flags &= ~CON_ENABLED; |
ac751efa | 3199 | console_unlock(); |
1da177e4 LT |
3200 | } |
3201 | EXPORT_SYMBOL(console_stop); | |
3202 | ||
3203 | void console_start(struct console *console) | |
3204 | { | |
ac751efa | 3205 | console_lock(); |
1da177e4 | 3206 | console->flags |= CON_ENABLED; |
ac751efa | 3207 | console_unlock(); |
3b604ca8 | 3208 | __pr_flush(console, 1000, true); |
1da177e4 LT |
3209 | } |
3210 | EXPORT_SYMBOL(console_start); | |
3211 | ||
7bf69395 FDN |
3212 | static int __read_mostly keep_bootcon; |
3213 | ||
3214 | static int __init keep_bootcon_setup(char *str) | |
3215 | { | |
3216 | keep_bootcon = 1; | |
27083bac | 3217 | pr_info("debug: skip boot console de-registration.\n"); |
7bf69395 FDN |
3218 | |
3219 | return 0; | |
3220 | } | |
3221 | ||
3222 | early_param("keep_bootcon", keep_bootcon_setup); | |
3223 | ||
ad8cd1db BH |
3224 | /* |
3225 | * This is called by register_console() to try to match | |
3226 | * the newly registered console with any of the ones selected | |
3227 | * by either the command line or add_preferred_console() and | |
3228 | * setup/enable it. | |
3229 | * | |
3230 | * Care need to be taken with consoles that are statically | |
3231 | * enabled such as netconsole | |
3232 | */ | |
ed758b30 PM |
3233 | static int try_enable_preferred_console(struct console *newcon, |
3234 | bool user_specified) | |
ad8cd1db BH |
3235 | { |
3236 | struct console_cmdline *c; | |
bba18a1a | 3237 | int i, err; |
ad8cd1db BH |
3238 | |
3239 | for (i = 0, c = console_cmdline; | |
3240 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
3241 | i++, c++) { | |
e369d822 BH |
3242 | if (c->user_specified != user_specified) |
3243 | continue; | |
ad8cd1db BH |
3244 | if (!newcon->match || |
3245 | newcon->match(newcon, c->name, c->index, c->options) != 0) { | |
3246 | /* default matching */ | |
3247 | BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name)); | |
3248 | if (strcmp(c->name, newcon->name) != 0) | |
3249 | continue; | |
3250 | if (newcon->index >= 0 && | |
3251 | newcon->index != c->index) | |
3252 | continue; | |
3253 | if (newcon->index < 0) | |
3254 | newcon->index = c->index; | |
3255 | ||
3256 | if (_braille_register_console(newcon, c)) | |
3257 | return 0; | |
3258 | ||
3259 | if (newcon->setup && | |
bba18a1a AS |
3260 | (err = newcon->setup(newcon, c->options)) != 0) |
3261 | return err; | |
ad8cd1db BH |
3262 | } |
3263 | newcon->flags |= CON_ENABLED; | |
f873efe8 | 3264 | if (i == preferred_console) |
ad8cd1db | 3265 | newcon->flags |= CON_CONSDEV; |
ad8cd1db BH |
3266 | return 0; |
3267 | } | |
3268 | ||
3269 | /* | |
3270 | * Some consoles, such as pstore and netconsole, can be enabled even | |
e369d822 | 3271 | * without matching. Accept the pre-enabled consoles only when match() |
50460376 | 3272 | * and setup() had a chance to be called. |
ad8cd1db | 3273 | */ |
e369d822 | 3274 | if (newcon->flags & CON_ENABLED && c->user_specified == user_specified) |
ad8cd1db BH |
3275 | return 0; |
3276 | ||
3277 | return -ENOENT; | |
3278 | } | |
3279 | ||
ed758b30 PM |
3280 | /* Try to enable the console unconditionally */ |
3281 | static void try_enable_default_console(struct console *newcon) | |
3282 | { | |
3283 | if (newcon->index < 0) | |
3284 | newcon->index = 0; | |
3285 | ||
3286 | if (newcon->setup && newcon->setup(newcon, NULL) != 0) | |
3287 | return; | |
3288 | ||
3289 | newcon->flags |= CON_ENABLED; | |
3290 | ||
4f546939 | 3291 | if (newcon->device) |
ed758b30 | 3292 | newcon->flags |= CON_CONSDEV; |
ed758b30 PM |
3293 | } |
3294 | ||
1fc0ca9e JO |
3295 | #define con_printk(lvl, con, fmt, ...) \ |
3296 | printk(lvl pr_fmt("%sconsole [%s%d] " fmt), \ | |
3297 | (con->flags & CON_BOOT) ? "boot" : "", \ | |
3298 | con->name, con->index, ##__VA_ARGS__) | |
3299 | ||
1da177e4 LT |
3300 | /* |
3301 | * The console driver calls this routine during kernel initialization | |
3302 | * to register the console printing procedure with printk() and to | |
3303 | * print any messages that were printed by the kernel before the | |
3304 | * console driver was initialized. | |
4d091611 RG |
3305 | * |
3306 | * This can happen pretty early during the boot process (because of | |
3307 | * early_printk) - sometimes before setup_arch() completes - be careful | |
3308 | * of what kernel features are used - they may not be initialised yet. | |
3309 | * | |
3310 | * There are two types of consoles - bootconsoles (early_printk) and | |
3311 | * "real" consoles (everything which is not a bootconsole) which are | |
3312 | * handled differently. | |
3313 | * - Any number of bootconsoles can be registered at any time. | |
3314 | * - As soon as a "real" console is registered, all bootconsoles | |
3315 | * will be unregistered automatically. | |
3316 | * - Once a "real" console is registered, any attempt to register a | |
3317 | * bootconsoles will be rejected | |
1da177e4 | 3318 | */ |
4d091611 | 3319 | void register_console(struct console *newcon) |
1da177e4 | 3320 | { |
5e8ba485 PM |
3321 | struct console *con; |
3322 | bool bootcon_enabled = false; | |
3323 | bool realcon_enabled = false; | |
ad8cd1db | 3324 | int err; |
1da177e4 | 3325 | |
5e8ba485 PM |
3326 | for_each_console(con) { |
3327 | if (WARN(con == newcon, "console '%s%d' already registered\n", | |
3328 | con->name, con->index)) | |
caa72c3b AS |
3329 | return; |
3330 | } | |
16cf48a6 | 3331 | |
5e8ba485 PM |
3332 | for_each_console(con) { |
3333 | if (con->flags & CON_BOOT) | |
3334 | bootcon_enabled = true; | |
3335 | else | |
3336 | realcon_enabled = true; | |
69331af7 GH |
3337 | } |
3338 | ||
5e8ba485 PM |
3339 | /* Do not register boot consoles when there already is a real one. */ |
3340 | if (newcon->flags & CON_BOOT && realcon_enabled) { | |
3341 | pr_info("Too late to register bootconsole %s%d\n", | |
3342 | newcon->name, newcon->index); | |
3343 | return; | |
3344 | } | |
4d091611 | 3345 | |
1da177e4 | 3346 | /* |
4f546939 PM |
3347 | * See if we want to enable this console driver by default. |
3348 | * | |
3349 | * Nope when a console is preferred by the command line, device | |
3350 | * tree, or SPCR. | |
3351 | * | |
3352 | * The first real console with tty binding (driver) wins. More | |
3353 | * consoles might get enabled before the right one is found. | |
3354 | * | |
3355 | * Note that a console with tty binding will have CON_CONSDEV | |
3356 | * flag set and will be first in the list. | |
1da177e4 | 3357 | */ |
4f546939 PM |
3358 | if (preferred_console < 0) { |
3359 | if (!console_drivers || !console_drivers->device || | |
3360 | console_drivers->flags & CON_BOOT) { | |
3361 | try_enable_default_console(newcon); | |
3362 | } | |
3363 | } | |
1da177e4 | 3364 | |
e369d822 | 3365 | /* See if this console matches one we selected on the command line */ |
ed758b30 | 3366 | err = try_enable_preferred_console(newcon, true); |
bbeddf52 | 3367 | |
e369d822 BH |
3368 | /* If not, try to match against the platform default(s) */ |
3369 | if (err == -ENOENT) | |
ed758b30 | 3370 | err = try_enable_preferred_console(newcon, false); |
1da177e4 | 3371 | |
ad8cd1db BH |
3372 | /* printk() messages are not printed to the Braille console. */ |
3373 | if (err || newcon->flags & CON_BRL) | |
1da177e4 LT |
3374 | return; |
3375 | ||
8259cf43 RG |
3376 | /* |
3377 | * If we have a bootconsole, and are switching to a real console, | |
3378 | * don't print everything out again, since when the boot console, and | |
3379 | * the real console are the same physical device, it's annoying to | |
3380 | * see the beginning boot messages twice | |
3381 | */ | |
5e8ba485 PM |
3382 | if (bootcon_enabled && |
3383 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) { | |
4d091611 | 3384 | newcon->flags &= ~CON_PRINTBUFFER; |
5e8ba485 | 3385 | } |
1da177e4 LT |
3386 | |
3387 | /* | |
3388 | * Put this console in the list - keep the | |
3389 | * preferred driver at the head of the list. | |
3390 | */ | |
ac751efa | 3391 | console_lock(); |
4d091611 RG |
3392 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
3393 | newcon->next = console_drivers; | |
3394 | console_drivers = newcon; | |
3395 | if (newcon->next) | |
3396 | newcon->next->flags &= ~CON_CONSDEV; | |
33225d7b BH |
3397 | /* Ensure this flag is always set for the head of the list */ |
3398 | newcon->flags |= CON_CONSDEV; | |
1da177e4 | 3399 | } else { |
4d091611 RG |
3400 | newcon->next = console_drivers->next; |
3401 | console_drivers->next = newcon; | |
1da177e4 | 3402 | } |
6fe29354 TH |
3403 | |
3404 | if (newcon->flags & CON_EXTENDED) | |
9627808d | 3405 | nr_ext_console_drivers++; |
6fe29354 | 3406 | |
a699449b | 3407 | newcon->dropped = 0; |
09c5ba0a | 3408 | newcon->thread = NULL; |
8e274732 JO |
3409 | newcon->blocked = true; |
3410 | mutex_init(&newcon->lock); | |
09c5ba0a | 3411 | |
4d091611 | 3412 | if (newcon->flags & CON_PRINTBUFFER) { |
636babdc | 3413 | /* Get a consistent copy of @syslog_seq. */ |
b371cbb5 | 3414 | mutex_lock(&syslog_lock); |
a699449b | 3415 | newcon->seq = syslog_seq; |
b371cbb5 | 3416 | mutex_unlock(&syslog_lock); |
a699449b JO |
3417 | } else { |
3418 | /* Begin with next message. */ | |
3419 | newcon->seq = prb_next_seq(prb); | |
1da177e4 | 3420 | } |
09c5ba0a JO |
3421 | |
3422 | if (printk_kthreads_available) | |
3423 | printk_start_kthread(newcon); | |
3424 | ||
ac751efa | 3425 | console_unlock(); |
fbc92a34 | 3426 | console_sysfs_notify(); |
8259cf43 RG |
3427 | |
3428 | /* | |
3429 | * By unregistering the bootconsoles after we enable the real console | |
3430 | * we get the "console xxx enabled" message on all the consoles - | |
3431 | * boot consoles, real consoles, etc - this is to ensure that end | |
3432 | * users know there might be something in the kernel's log buffer that | |
3433 | * went to the bootconsole (that they do not see on the real console) | |
3434 | */ | |
1fc0ca9e | 3435 | con_printk(KERN_INFO, newcon, "enabled\n"); |
5e8ba485 | 3436 | if (bootcon_enabled && |
7bf69395 FDN |
3437 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && |
3438 | !keep_bootcon) { | |
6b802394 KC |
3439 | /* We need to iterate through all boot consoles, to make |
3440 | * sure we print everything out, before we unregister them. | |
8259cf43 | 3441 | */ |
5e8ba485 PM |
3442 | for_each_console(con) |
3443 | if (con->flags & CON_BOOT) | |
3444 | unregister_console(con); | |
8259cf43 | 3445 | } |
1da177e4 LT |
3446 | } |
3447 | EXPORT_SYMBOL(register_console); | |
3448 | ||
40dc5651 | 3449 | int unregister_console(struct console *console) |
1da177e4 | 3450 | { |
09c5ba0a | 3451 | struct task_struct *thd; |
12825e6b | 3452 | struct console *con; |
bbeddf52 | 3453 | int res; |
1da177e4 | 3454 | |
1fc0ca9e | 3455 | con_printk(KERN_INFO, console, "disabled\n"); |
6b802394 | 3456 | |
bbeddf52 | 3457 | res = _braille_unregister_console(console); |
bb72e398 | 3458 | if (res < 0) |
bbeddf52 | 3459 | return res; |
bb72e398 AS |
3460 | if (res > 0) |
3461 | return 0; | |
f7511d5f | 3462 | |
bb72e398 | 3463 | res = -ENODEV; |
ac751efa | 3464 | console_lock(); |
1da177e4 LT |
3465 | if (console_drivers == console) { |
3466 | console_drivers=console->next; | |
3467 | res = 0; | |
12825e6b AS |
3468 | } else { |
3469 | for_each_console(con) { | |
3470 | if (con->next == console) { | |
3471 | con->next = console->next; | |
1da177e4 LT |
3472 | res = 0; |
3473 | break; | |
40dc5651 | 3474 | } |
1da177e4 LT |
3475 | } |
3476 | } | |
40dc5651 | 3477 | |
e78bedbd AS |
3478 | if (res) |
3479 | goto out_disable_unlock; | |
3480 | ||
3481 | if (console->flags & CON_EXTENDED) | |
6fe29354 TH |
3482 | nr_ext_console_drivers--; |
3483 | ||
69331af7 | 3484 | /* |
ab4af03a GE |
3485 | * If this isn't the last console and it has CON_CONSDEV set, we |
3486 | * need to set it on the next preferred console. | |
1da177e4 | 3487 | */ |
69331af7 | 3488 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 3489 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 | 3490 | |
7fa21dd8 | 3491 | console->flags &= ~CON_ENABLED; |
09c5ba0a JO |
3492 | |
3493 | /* | |
3494 | * console->thread can only be cleared under the console lock. But | |
3495 | * stopping the thread must be done without the console lock. The | |
3496 | * task that clears @thread is the task that stops the kthread. | |
3497 | */ | |
3498 | thd = console->thread; | |
3499 | console->thread = NULL; | |
3500 | ||
ac751efa | 3501 | console_unlock(); |
09c5ba0a JO |
3502 | |
3503 | if (thd) | |
3504 | kthread_stop(thd); | |
3505 | ||
fbc92a34 | 3506 | console_sysfs_notify(); |
e78bedbd | 3507 | |
ed31685c AS |
3508 | if (console->exit) |
3509 | res = console->exit(console); | |
3510 | ||
e78bedbd AS |
3511 | return res; |
3512 | ||
3513 | out_disable_unlock: | |
3514 | console->flags &= ~CON_ENABLED; | |
3515 | console_unlock(); | |
3516 | ||
1da177e4 LT |
3517 | return res; |
3518 | } | |
3519 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 3520 | |
0c688614 NP |
3521 | /* |
3522 | * Initialize the console device. This is called *early*, so | |
3523 | * we can't necessarily depend on lots of kernel help here. | |
3524 | * Just do some early initializations, and do the complex setup | |
3525 | * later. | |
3526 | */ | |
3527 | void __init console_init(void) | |
3528 | { | |
58eacfff | 3529 | int ret; |
1b1eeca7 AB |
3530 | initcall_t call; |
3531 | initcall_entry_t *ce; | |
0c688614 NP |
3532 | |
3533 | /* Setup the default TTY line discipline. */ | |
3534 | n_tty_init(); | |
3535 | ||
3536 | /* | |
3537 | * set up the console device so that later boot sequences can | |
3538 | * inform about problems etc.. | |
3539 | */ | |
1b1eeca7 | 3540 | ce = __con_initcall_start; |
58eacfff | 3541 | trace_initcall_level("console"); |
1b1eeca7 AB |
3542 | while (ce < __con_initcall_end) { |
3543 | call = initcall_from_entry(ce); | |
3544 | trace_initcall_start(call); | |
3545 | ret = call(); | |
3546 | trace_initcall_finish(call, ret); | |
3547 | ce++; | |
0c688614 NP |
3548 | } |
3549 | } | |
3550 | ||
81cc26f2 TR |
3551 | /* |
3552 | * Some boot consoles access data that is in the init section and which will | |
3553 | * be discarded after the initcalls have been run. To make sure that no code | |
3554 | * will access this data, unregister the boot consoles in a late initcall. | |
3555 | * | |
3556 | * If for some reason, such as deferred probe or the driver being a loadable | |
3557 | * module, the real console hasn't registered yet at this point, there will | |
3558 | * be a brief interval in which no messages are logged to the console, which | |
3559 | * makes it difficult to diagnose problems that occur during this time. | |
3560 | * | |
3561 | * To mitigate this problem somewhat, only unregister consoles whose memory | |
2b1be689 | 3562 | * intersects with the init section. Note that all other boot consoles will |
acebb559 | 3563 | * get unregistered when the real preferred console is registered. |
81cc26f2 | 3564 | */ |
034260d6 | 3565 | static int __init printk_late_init(void) |
0c5564bd | 3566 | { |
4d091611 | 3567 | struct console *con; |
90b14889 | 3568 | int ret; |
4d091611 RG |
3569 | |
3570 | for_each_console(con) { | |
5a814231 PM |
3571 | if (!(con->flags & CON_BOOT)) |
3572 | continue; | |
3573 | ||
3574 | /* Check addresses that might be used for enabled consoles. */ | |
3575 | if (init_section_intersects(con, sizeof(*con)) || | |
3576 | init_section_contains(con->write, 0) || | |
3577 | init_section_contains(con->read, 0) || | |
3578 | init_section_contains(con->device, 0) || | |
3579 | init_section_contains(con->unblank, 0) || | |
3580 | init_section_contains(con->data, 0)) { | |
81cc26f2 | 3581 | /* |
2b1be689 MR |
3582 | * Please, consider moving the reported consoles out |
3583 | * of the init section. | |
81cc26f2 | 3584 | */ |
2b1be689 MR |
3585 | pr_warn("bootconsole [%s%d] uses init memory and must be disabled even before the real one is ready\n", |
3586 | con->name, con->index); | |
3587 | unregister_console(con); | |
cb00e99c | 3588 | } |
0c5564bd | 3589 | } |
90b14889 SAS |
3590 | ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL, |
3591 | console_cpu_notify); | |
3592 | WARN_ON(ret < 0); | |
3593 | ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "printk:online", | |
3594 | console_cpu_notify, NULL); | |
3595 | WARN_ON(ret < 0); | |
faaa357a | 3596 | printk_sysctl_init(); |
0c5564bd RG |
3597 | return 0; |
3598 | } | |
034260d6 | 3599 | late_initcall(printk_late_init); |
0c5564bd | 3600 | |
09c5ba0a JO |
3601 | static int __init printk_activate_kthreads(void) |
3602 | { | |
3603 | struct console *con; | |
3604 | ||
3605 | console_lock(); | |
3606 | printk_kthreads_available = true; | |
3607 | for_each_console(con) | |
3608 | printk_start_kthread(con); | |
3609 | console_unlock(); | |
3610 | ||
3611 | return 0; | |
3612 | } | |
3613 | early_initcall(printk_activate_kthreads); | |
3614 | ||
7ef3d2fd | 3615 | #if defined CONFIG_PRINTK |
3b604ca8 JO |
3616 | /* If @con is specified, only wait for that console. Otherwise wait for all. */ |
3617 | static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) | |
3618 | { | |
3619 | int remaining = timeout_ms; | |
3620 | struct console *c; | |
3621 | u64 last_diff = 0; | |
3622 | u64 printk_seq; | |
3623 | u64 diff; | |
3624 | u64 seq; | |
3625 | ||
3626 | might_sleep(); | |
3627 | ||
3628 | seq = prb_next_seq(prb); | |
3629 | ||
3630 | for (;;) { | |
3631 | diff = 0; | |
3632 | ||
3633 | console_lock(); | |
3634 | for_each_console(c) { | |
3635 | if (con && con != c) | |
3636 | continue; | |
3637 | if (!console_is_usable(c)) | |
3638 | continue; | |
3639 | printk_seq = c->seq; | |
3640 | if (printk_seq < seq) | |
3641 | diff += seq - printk_seq; | |
3642 | } | |
3643 | console_unlock(); | |
3644 | ||
3645 | if (diff != last_diff && reset_on_progress) | |
3646 | remaining = timeout_ms; | |
3647 | ||
3648 | if (diff == 0 || remaining == 0) | |
3649 | break; | |
3650 | ||
3651 | if (remaining < 0) { | |
3652 | /* no timeout limit */ | |
3653 | msleep(100); | |
3654 | } else if (remaining < 100) { | |
3655 | msleep(remaining); | |
3656 | remaining = 0; | |
3657 | } else { | |
3658 | msleep(100); | |
3659 | remaining -= 100; | |
3660 | } | |
3661 | ||
3662 | last_diff = diff; | |
3663 | } | |
3664 | ||
3665 | return (diff == 0); | |
3666 | } | |
3667 | ||
3668 | /** | |
3669 | * pr_flush() - Wait for printing threads to catch up. | |
3670 | * | |
3671 | * @timeout_ms: The maximum time (in ms) to wait. | |
3672 | * @reset_on_progress: Reset the timeout if forward progress is seen. | |
3673 | * | |
3674 | * A value of 0 for @timeout_ms means no waiting will occur. A value of -1 | |
3675 | * represents infinite waiting. | |
3676 | * | |
3677 | * If @reset_on_progress is true, the timeout will be reset whenever any | |
3678 | * printer has been seen to make some forward progress. | |
3679 | * | |
3680 | * Context: Process context. May sleep while acquiring console lock. | |
3681 | * Return: true if all enabled printers are caught up. | |
3682 | */ | |
3683 | bool pr_flush(int timeout_ms, bool reset_on_progress) | |
3684 | { | |
3685 | return __pr_flush(NULL, timeout_ms, reset_on_progress); | |
3686 | } | |
3687 | EXPORT_SYMBOL(pr_flush); | |
3688 | ||
09c5ba0a JO |
3689 | static void __printk_fallback_preferred_direct(void) |
3690 | { | |
3691 | printk_prefer_direct_enter(); | |
3692 | pr_err("falling back to preferred direct printing\n"); | |
3693 | printk_kthreads_available = false; | |
3694 | } | |
3695 | ||
3696 | /* | |
3697 | * Enter preferred direct printing, but never exit. Mark console threads as | |
3698 | * unavailable. The system is then forever in preferred direct printing and | |
3699 | * any printing threads will exit. | |
3700 | * | |
3701 | * Must *not* be called under console_lock. Use | |
3702 | * __printk_fallback_preferred_direct() if already holding console_lock. | |
3703 | */ | |
3704 | static void printk_fallback_preferred_direct(void) | |
3705 | { | |
3706 | console_lock(); | |
3707 | __printk_fallback_preferred_direct(); | |
3708 | console_unlock(); | |
3709 | } | |
3710 | ||
8e274732 JO |
3711 | /* |
3712 | * Print a record for a given console, not allowing another printk() caller | |
3713 | * to take over. This is appropriate for contexts that do not have the | |
3714 | * console_lock. | |
3715 | * | |
3716 | * See __console_emit_next_record() for argument and return details. | |
3717 | */ | |
3718 | static bool console_emit_next_record(struct console *con, char *text, char *ext_text, | |
3719 | char *dropped_text) | |
3720 | { | |
3721 | return __console_emit_next_record(con, text, ext_text, dropped_text, NULL); | |
3722 | } | |
3723 | ||
09c5ba0a JO |
3724 | static bool printer_should_wake(struct console *con, u64 seq) |
3725 | { | |
3726 | short flags; | |
3727 | ||
3728 | if (kthread_should_stop() || !printk_kthreads_available) | |
3729 | return true; | |
3730 | ||
8e274732 | 3731 | if (con->blocked || |
c3230283 PM |
3732 | console_kthreads_atomically_blocked() || |
3733 | system_state > SYSTEM_RUNNING || | |
3734 | oops_in_progress) { | |
09c5ba0a | 3735 | return false; |
8e274732 | 3736 | } |
09c5ba0a JO |
3737 | |
3738 | /* | |
3739 | * This is an unsafe read from con->flags, but a false positive is | |
3740 | * not a problem. Worst case it would allow the printer to wake up | |
3741 | * although it is disabled. But the printer will notice that when | |
3742 | * attempting to print and instead go back to sleep. | |
3743 | */ | |
3744 | flags = data_race(READ_ONCE(con->flags)); | |
3745 | ||
3746 | if (!__console_is_usable(flags)) | |
3747 | return false; | |
3748 | ||
3749 | return prb_read_valid(prb, seq, NULL); | |
3750 | } | |
3751 | ||
3752 | static int printk_kthread_func(void *data) | |
3753 | { | |
3754 | struct console *con = data; | |
3755 | char *dropped_text = NULL; | |
3756 | char *ext_text = NULL; | |
09c5ba0a JO |
3757 | u64 seq = 0; |
3758 | char *text; | |
3759 | int error; | |
3760 | ||
3761 | text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL); | |
3762 | if (!text) { | |
3763 | con_printk(KERN_ERR, con, "failed to allocate text buffer\n"); | |
3764 | printk_fallback_preferred_direct(); | |
3765 | goto out; | |
3766 | } | |
3767 | ||
3768 | if (con->flags & CON_EXTENDED) { | |
3769 | ext_text = kmalloc(CONSOLE_EXT_LOG_MAX, GFP_KERNEL); | |
3770 | if (!ext_text) { | |
3771 | con_printk(KERN_ERR, con, "failed to allocate ext_text buffer\n"); | |
3772 | printk_fallback_preferred_direct(); | |
3773 | goto out; | |
3774 | } | |
3775 | } else { | |
3776 | dropped_text = kmalloc(DROPPED_TEXT_MAX, GFP_KERNEL); | |
3777 | if (!dropped_text) { | |
3778 | con_printk(KERN_ERR, con, "failed to allocate dropped_text buffer\n"); | |
3779 | printk_fallback_preferred_direct(); | |
3780 | goto out; | |
3781 | } | |
3782 | } | |
3783 | ||
3784 | con_printk(KERN_INFO, con, "printing thread started\n"); | |
3785 | ||
3786 | for (;;) { | |
3787 | /* | |
3788 | * Guarantee this task is visible on the waitqueue before | |
3789 | * checking the wake condition. | |
3790 | * | |
3791 | * The full memory barrier within set_current_state() of | |
3792 | * prepare_to_wait_event() pairs with the full memory barrier | |
3793 | * within wq_has_sleeper(). | |
3794 | * | |
3795 | * This pairs with __wake_up_klogd:A. | |
3796 | */ | |
3797 | error = wait_event_interruptible(log_wait, | |
3798 | printer_should_wake(con, seq)); /* LMM(printk_kthread_func:A) */ | |
3799 | ||
3800 | if (kthread_should_stop() || !printk_kthreads_available) | |
3801 | break; | |
3802 | ||
3803 | if (error) | |
3804 | continue; | |
3805 | ||
8e274732 JO |
3806 | error = mutex_lock_interruptible(&con->lock); |
3807 | if (error) | |
3808 | continue; | |
09c5ba0a | 3809 | |
8e274732 JO |
3810 | if (con->blocked || |
3811 | !console_kthread_printing_tryenter()) { | |
3812 | /* Another context has locked the console_lock. */ | |
3813 | mutex_unlock(&con->lock); | |
09c5ba0a JO |
3814 | continue; |
3815 | } | |
3816 | ||
8e274732 JO |
3817 | /* |
3818 | * Although this context has not locked the console_lock, it | |
3819 | * is known that the console_lock is not locked and it is not | |
3820 | * possible for any other context to lock the console_lock. | |
3821 | * Therefore it is safe to read con->flags. | |
3822 | */ | |
3823 | ||
3824 | if (!__console_is_usable(con->flags)) { | |
3825 | console_kthread_printing_exit(); | |
3826 | mutex_unlock(&con->lock); | |
09c5ba0a JO |
3827 | continue; |
3828 | } | |
3829 | ||
3830 | /* | |
3831 | * Even though the printk kthread is always preemptible, it is | |
3832 | * still not allowed to call cond_resched() from within | |
3833 | * console drivers. The task may become non-preemptible in the | |
3834 | * console driver call chain. For example, vt_console_print() | |
3835 | * takes a spinlock and then can call into fbcon_redraw(), | |
3836 | * which can conditionally invoke cond_resched(). | |
3837 | */ | |
3838 | console_may_schedule = 0; | |
8e274732 | 3839 | console_emit_next_record(con, text, ext_text, dropped_text); |
09c5ba0a JO |
3840 | |
3841 | seq = con->seq; | |
3842 | ||
8e274732 JO |
3843 | console_kthread_printing_exit(); |
3844 | ||
3845 | mutex_unlock(&con->lock); | |
09c5ba0a JO |
3846 | } |
3847 | ||
3848 | con_printk(KERN_INFO, con, "printing thread stopped\n"); | |
3849 | out: | |
3850 | kfree(dropped_text); | |
3851 | kfree(ext_text); | |
3852 | kfree(text); | |
3853 | ||
3854 | console_lock(); | |
3855 | /* | |
3856 | * If this kthread is being stopped by another task, con->thread will | |
3857 | * already be NULL. That is fine. The important thing is that it is | |
3858 | * NULL after the kthread exits. | |
3859 | */ | |
3860 | con->thread = NULL; | |
3861 | console_unlock(); | |
3862 | ||
3863 | return 0; | |
3864 | } | |
3865 | ||
3866 | /* Must be called under console_lock. */ | |
3867 | static void printk_start_kthread(struct console *con) | |
3868 | { | |
3869 | /* | |
3870 | * Do not start a kthread if there is no write() callback. The | |
3871 | * kthreads assume the write() callback exists. | |
3872 | */ | |
3873 | if (!con->write) | |
3874 | return; | |
3875 | ||
3876 | con->thread = kthread_run(printk_kthread_func, con, | |
3877 | "pr/%s%d", con->name, con->index); | |
3878 | if (IS_ERR(con->thread)) { | |
3879 | con->thread = NULL; | |
3880 | con_printk(KERN_ERR, con, "unable to start printing thread\n"); | |
3881 | __printk_fallback_preferred_direct(); | |
3882 | return; | |
3883 | } | |
3884 | } | |
3885 | ||
dc72c32e FW |
3886 | /* |
3887 | * Delayed printk version, for scheduler-internal messages: | |
3888 | */ | |
09c5ba0a JO |
3889 | #define PRINTK_PENDING_WAKEUP 0x01 |
3890 | #define PRINTK_PENDING_DIRECT_OUTPUT 0x02 | |
dc72c32e FW |
3891 | |
3892 | static DEFINE_PER_CPU(int, printk_pending); | |
dc72c32e FW |
3893 | |
3894 | static void wake_up_klogd_work_func(struct irq_work *irq_work) | |
3895 | { | |
2ba3673d | 3896 | int pending = this_cpu_xchg(printk_pending, 0); |
dc72c32e | 3897 | |
09c5ba0a JO |
3898 | if (pending & PRINTK_PENDING_DIRECT_OUTPUT) { |
3899 | printk_prefer_direct_enter(); | |
3900 | ||
458df9fd SR |
3901 | /* If trylock fails, someone else is doing the printing */ |
3902 | if (console_trylock()) | |
3903 | console_unlock(); | |
09c5ba0a JO |
3904 | |
3905 | printk_prefer_direct_exit(); | |
dc72c32e FW |
3906 | } |
3907 | ||
3908 | if (pending & PRINTK_PENDING_WAKEUP) | |
809631e2 | 3909 | wake_up_interruptible(&log_wait); |
dc72c32e FW |
3910 | } |
3911 | ||
7a9f50a0 PZ |
3912 | static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = |
3913 | IRQ_WORK_INIT_LAZY(wake_up_klogd_work_func); | |
dc72c32e | 3914 | |
5341b93d | 3915 | static void __wake_up_klogd(int val) |
dc72c32e | 3916 | { |
ab6f762f SS |
3917 | if (!printk_percpu_data_ready()) |
3918 | return; | |
3919 | ||
dc72c32e | 3920 | preempt_disable(); |
1f5d7830 JO |
3921 | /* |
3922 | * Guarantee any new records can be seen by tasks preparing to wait | |
3923 | * before this context checks if the wait queue is empty. | |
3924 | * | |
3925 | * The full memory barrier within wq_has_sleeper() pairs with the full | |
3926 | * memory barrier within set_current_state() of | |
3927 | * prepare_to_wait_event(), which is called after ___wait_event() adds | |
3928 | * the waiter but before it has checked the wait condition. | |
3929 | * | |
09c5ba0a JO |
3930 | * This pairs with devkmsg_read:A, syslog_print:A, and |
3931 | * printk_kthread_func:A. | |
1f5d7830 | 3932 | */ |
5341b93d | 3933 | if (wq_has_sleeper(&log_wait) || /* LMM(__wake_up_klogd:A) */ |
09c5ba0a | 3934 | (val & PRINTK_PENDING_DIRECT_OUTPUT)) { |
5341b93d | 3935 | this_cpu_or(printk_pending, val); |
bb964a92 | 3936 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
dc72c32e FW |
3937 | } |
3938 | preempt_enable(); | |
3939 | } | |
717115e1 | 3940 | |
5341b93d | 3941 | void wake_up_klogd(void) |
600e1458 | 3942 | { |
5341b93d JO |
3943 | __wake_up_klogd(PRINTK_PENDING_WAKEUP); |
3944 | } | |
ab6f762f | 3945 | |
5341b93d JO |
3946 | void defer_console_output(void) |
3947 | { | |
3948 | /* | |
3949 | * New messages may have been added directly to the ringbuffer | |
3950 | * using vprintk_store(), so wake any waiters as well. | |
3951 | */ | |
09c5ba0a JO |
3952 | int val = PRINTK_PENDING_WAKEUP; |
3953 | ||
3954 | /* | |
3955 | * Make sure that some context will print the messages when direct | |
3956 | * printing is allowed. This happens in situations when the kthreads | |
3957 | * may not be as reliable or perhaps unusable. | |
3958 | */ | |
3959 | if (allow_direct_printing()) | |
3960 | val |= PRINTK_PENDING_DIRECT_OUTPUT; | |
3961 | ||
3962 | __wake_up_klogd(val); | |
a338f84d PM |
3963 | } |
3964 | ||
5d5e4522 NP |
3965 | void printk_trigger_flush(void) |
3966 | { | |
3967 | defer_console_output(); | |
3968 | } | |
3969 | ||
a338f84d PM |
3970 | int vprintk_deferred(const char *fmt, va_list args) |
3971 | { | |
3972 | int r; | |
3973 | ||
74caba7f | 3974 | r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, fmt, args); |
a338f84d | 3975 | defer_console_output(); |
600e1458 PZ |
3976 | |
3977 | return r; | |
3978 | } | |
3979 | ||
33701557 | 3980 | int _printk_deferred(const char *fmt, ...) |
719f6a70 PM |
3981 | { |
3982 | va_list args; | |
3983 | int r; | |
3984 | ||
3985 | va_start(args, fmt); | |
3986 | r = vprintk_deferred(fmt, args); | |
3987 | va_end(args); | |
3988 | ||
3989 | return r; | |
3990 | } | |
3991 | ||
1da177e4 LT |
3992 | /* |
3993 | * printk rate limiting, lifted from the networking subsystem. | |
3994 | * | |
641de9d8 UKK |
3995 | * This enforces a rate limit: not more than 10 kernel messages |
3996 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 3997 | */ |
641de9d8 UKK |
3998 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
3999 | ||
5c828713 | 4000 | int __printk_ratelimit(const char *func) |
1da177e4 | 4001 | { |
5c828713 | 4002 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 4003 | } |
5c828713 | 4004 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
4005 | |
4006 | /** | |
4007 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
4008 | * @caller_jiffies: pointer to caller's state | |
4009 | * @interval_msecs: minimum interval between prints | |
4010 | * | |
4011 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
4012 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
4013 | * returned true. | |
4014 | */ | |
4015 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
4016 | unsigned int interval_msecs) | |
4017 | { | |
249771b8 AE |
4018 | unsigned long elapsed = jiffies - *caller_jiffies; |
4019 | ||
4020 | if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) | |
4021 | return false; | |
4022 | ||
4023 | *caller_jiffies = jiffies; | |
4024 | return true; | |
f46c4833 AM |
4025 | } |
4026 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
4027 | |
4028 | static DEFINE_SPINLOCK(dump_list_lock); | |
4029 | static LIST_HEAD(dump_list); | |
4030 | ||
4031 | /** | |
4032 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 4033 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
4034 | * |
4035 | * Adds a kernel log dumper to the system. The dump callback in the | |
4036 | * structure will be called when the kernel oopses or panics and must be | |
4037 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
4038 | */ | |
4039 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
4040 | { | |
4041 | unsigned long flags; | |
4042 | int err = -EBUSY; | |
4043 | ||
4044 | /* The dump callback needs to be set */ | |
4045 | if (!dumper->dump) | |
4046 | return -EINVAL; | |
4047 | ||
4048 | spin_lock_irqsave(&dump_list_lock, flags); | |
4049 | /* Don't allow registering multiple times */ | |
4050 | if (!dumper->registered) { | |
4051 | dumper->registered = 1; | |
fb842b00 | 4052 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
4053 | err = 0; |
4054 | } | |
4055 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
4056 | ||
4057 | return err; | |
4058 | } | |
4059 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
4060 | ||
4061 | /** | |
4062 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 4063 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
4064 | * |
4065 | * Removes a dump device from the system. Returns zero on success and | |
4066 | * %-EINVAL otherwise. | |
4067 | */ | |
4068 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
4069 | { | |
4070 | unsigned long flags; | |
4071 | int err = -EINVAL; | |
4072 | ||
4073 | spin_lock_irqsave(&dump_list_lock, flags); | |
4074 | if (dumper->registered) { | |
4075 | dumper->registered = 0; | |
fb842b00 | 4076 | list_del_rcu(&dumper->list); |
456b565c SK |
4077 | err = 0; |
4078 | } | |
4079 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 4080 | synchronize_rcu(); |
456b565c SK |
4081 | |
4082 | return err; | |
4083 | } | |
4084 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
4085 | ||
7ff9554b KS |
4086 | static bool always_kmsg_dump; |
4087 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); | |
4088 | ||
fb13cb8a KC |
4089 | const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason) |
4090 | { | |
4091 | switch (reason) { | |
4092 | case KMSG_DUMP_PANIC: | |
4093 | return "Panic"; | |
4094 | case KMSG_DUMP_OOPS: | |
4095 | return "Oops"; | |
4096 | case KMSG_DUMP_EMERG: | |
4097 | return "Emergency"; | |
4098 | case KMSG_DUMP_SHUTDOWN: | |
4099 | return "Shutdown"; | |
4100 | default: | |
4101 | return "Unknown"; | |
4102 | } | |
4103 | } | |
4104 | EXPORT_SYMBOL_GPL(kmsg_dump_reason_str); | |
4105 | ||
456b565c SK |
4106 | /** |
4107 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
4108 | * @reason: the reason (oops, panic etc) for dumping | |
4109 | * | |
e2ae715d KS |
4110 | * Call each of the registered dumper's dump() callback, which can |
4111 | * retrieve the kmsg records with kmsg_dump_get_line() or | |
4112 | * kmsg_dump_get_buffer(). | |
456b565c SK |
4113 | */ |
4114 | void kmsg_dump(enum kmsg_dump_reason reason) | |
4115 | { | |
456b565c | 4116 | struct kmsg_dumper *dumper; |
456b565c | 4117 | |
e2ae715d KS |
4118 | rcu_read_lock(); |
4119 | list_for_each_entry_rcu(dumper, &dump_list, list) { | |
b1f6f161 PT |
4120 | enum kmsg_dump_reason max_reason = dumper->max_reason; |
4121 | ||
4122 | /* | |
4123 | * If client has not provided a specific max_reason, default | |
4124 | * to KMSG_DUMP_OOPS, unless always_kmsg_dump was set. | |
4125 | */ | |
4126 | if (max_reason == KMSG_DUMP_UNDEF) { | |
4127 | max_reason = always_kmsg_dump ? KMSG_DUMP_MAX : | |
4128 | KMSG_DUMP_OOPS; | |
4129 | } | |
4130 | if (reason > max_reason) | |
e2ae715d KS |
4131 | continue; |
4132 | ||
e2ae715d KS |
4133 | /* invoke dumper which will iterate over records */ |
4134 | dumper->dump(dumper, reason); | |
e2ae715d KS |
4135 | } |
4136 | rcu_read_unlock(); | |
4137 | } | |
4138 | ||
4139 | /** | |
a4f98765 | 4140 | * kmsg_dump_get_line - retrieve one kmsg log line |
f9f3f02d | 4141 | * @iter: kmsg dump iterator |
e2ae715d KS |
4142 | * @syslog: include the "<4>" prefixes |
4143 | * @line: buffer to copy the line to | |
4144 | * @size: maximum size of the buffer | |
4145 | * @len: length of line placed into buffer | |
4146 | * | |
4147 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
4148 | * record, and copy one record into the provided buffer. | |
4149 | * | |
4150 | * Consecutive calls will return the next available record moving | |
4151 | * towards the end of the buffer with the youngest messages. | |
4152 | * | |
4153 | * A return value of FALSE indicates that there are no more records to | |
4154 | * read. | |
4155 | */ | |
a4f98765 JO |
4156 | bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog, |
4157 | char *line, size_t size, size_t *len) | |
e2ae715d | 4158 | { |
f9f3f02d | 4159 | u64 min_seq = latched_seq_read_nolock(&clear_seq); |
896fbe20 JO |
4160 | struct printk_info info; |
4161 | unsigned int line_count; | |
4162 | struct printk_record r; | |
e2ae715d KS |
4163 | size_t l = 0; |
4164 | bool ret = false; | |
4165 | ||
f9f3f02d JO |
4166 | if (iter->cur_seq < min_seq) |
4167 | iter->cur_seq = min_seq; | |
4168 | ||
f35efc78 | 4169 | prb_rec_init_rd(&r, &info, line, size); |
896fbe20 | 4170 | |
896fbe20 JO |
4171 | /* Read text or count text lines? */ |
4172 | if (line) { | |
f9f3f02d | 4173 | if (!prb_read_valid(prb, iter->cur_seq, &r)) |
896fbe20 JO |
4174 | goto out; |
4175 | l = record_print_text(&r, syslog, printk_time); | |
4176 | } else { | |
f9f3f02d | 4177 | if (!prb_read_valid_info(prb, iter->cur_seq, |
896fbe20 JO |
4178 | &info, &line_count)) { |
4179 | goto out; | |
4180 | } | |
4181 | l = get_record_print_text_size(&info, line_count, syslog, | |
4182 | printk_time); | |
456b565c | 4183 | |
896fbe20 | 4184 | } |
e2ae715d | 4185 | |
f9f3f02d | 4186 | iter->cur_seq = r.info->seq + 1; |
e2ae715d | 4187 | ret = true; |
e2ae715d KS |
4188 | out: |
4189 | if (len) | |
4190 | *len = l; | |
4191 | return ret; | |
4192 | } | |
4193 | EXPORT_SYMBOL_GPL(kmsg_dump_get_line); | |
4194 | ||
4195 | /** | |
4196 | * kmsg_dump_get_buffer - copy kmsg log lines | |
f9f3f02d | 4197 | * @iter: kmsg dump iterator |
e2ae715d | 4198 | * @syslog: include the "<4>" prefixes |
4f0f4af5 | 4199 | * @buf: buffer to copy the line to |
e2ae715d | 4200 | * @size: maximum size of the buffer |
726b5097 | 4201 | * @len_out: length of line placed into buffer |
e2ae715d KS |
4202 | * |
4203 | * Start at the end of the kmsg buffer and fill the provided buffer | |
547bbf7d | 4204 | * with as many of the *youngest* kmsg records that fit into it. |
e2ae715d KS |
4205 | * If the buffer is large enough, all available kmsg records will be |
4206 | * copied with a single call. | |
4207 | * | |
4208 | * Consecutive calls will fill the buffer with the next block of | |
4209 | * available older records, not including the earlier retrieved ones. | |
4210 | * | |
4211 | * A return value of FALSE indicates that there are no more records to | |
4212 | * read. | |
4213 | */ | |
f9f3f02d | 4214 | bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog, |
726b5097 | 4215 | char *buf, size_t size, size_t *len_out) |
e2ae715d | 4216 | { |
f9f3f02d | 4217 | u64 min_seq = latched_seq_read_nolock(&clear_seq); |
896fbe20 | 4218 | struct printk_info info; |
896fbe20 | 4219 | struct printk_record r; |
e2ae715d | 4220 | u64 seq; |
e2ae715d | 4221 | u64 next_seq; |
726b5097 | 4222 | size_t len = 0; |
e2ae715d | 4223 | bool ret = false; |
e80c1a9d | 4224 | bool time = printk_time; |
e2ae715d | 4225 | |
5f6c7648 | 4226 | if (!buf || !size) |
e2ae715d KS |
4227 | goto out; |
4228 | ||
f9f3f02d JO |
4229 | if (iter->cur_seq < min_seq) |
4230 | iter->cur_seq = min_seq; | |
4231 | ||
f9f3f02d JO |
4232 | if (prb_read_valid_info(prb, iter->cur_seq, &info, NULL)) { |
4233 | if (info.seq != iter->cur_seq) { | |
13791c80 | 4234 | /* messages are gone, move to first available one */ |
f9f3f02d | 4235 | iter->cur_seq = info.seq; |
13791c80 | 4236 | } |
e2ae715d KS |
4237 | } |
4238 | ||
4239 | /* last entry */ | |
93d102f0 | 4240 | if (iter->cur_seq >= iter->next_seq) |
e2ae715d | 4241 | goto out; |
e2ae715d | 4242 | |
726b5097 JO |
4243 | /* |
4244 | * Find first record that fits, including all following records, | |
4260e0e5 JO |
4245 | * into the user-provided buffer for this dump. Pass in size-1 |
4246 | * because this function (by way of record_print_text()) will | |
4247 | * not write more than size-1 bytes of text into @buf. | |
726b5097 | 4248 | */ |
f9f3f02d | 4249 | seq = find_first_fitting_seq(iter->cur_seq, iter->next_seq, |
4260e0e5 | 4250 | size - 1, syslog, time); |
e2ae715d | 4251 | |
726b5097 JO |
4252 | /* |
4253 | * Next kmsg_dump_get_buffer() invocation will dump block of | |
4254 | * older records stored right before this one. | |
4255 | */ | |
e2ae715d | 4256 | next_seq = seq; |
e2ae715d | 4257 | |
726b5097 JO |
4258 | prb_rec_init_rd(&r, &info, buf, size); |
4259 | ||
4260 | len = 0; | |
4261 | prb_for_each_record(seq, prb, seq, &r) { | |
f9f3f02d | 4262 | if (r.info->seq >= iter->next_seq) |
896fbe20 JO |
4263 | break; |
4264 | ||
726b5097 | 4265 | len += record_print_text(&r, syslog, time); |
896fbe20 | 4266 | |
726b5097 JO |
4267 | /* Adjust record to store to remaining buffer space. */ |
4268 | prb_rec_init_rd(&r, &info, buf + len, size - len); | |
e2ae715d KS |
4269 | } |
4270 | ||
f9f3f02d | 4271 | iter->next_seq = next_seq; |
e2ae715d | 4272 | ret = true; |
e2ae715d | 4273 | out: |
726b5097 JO |
4274 | if (len_out) |
4275 | *len_out = len; | |
e2ae715d KS |
4276 | return ret; |
4277 | } | |
4278 | EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); | |
456b565c | 4279 | |
e2ae715d | 4280 | /** |
325606af | 4281 | * kmsg_dump_rewind - reset the iterator |
f9f3f02d | 4282 | * @iter: kmsg dump iterator |
e2ae715d KS |
4283 | * |
4284 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
4285 | * kmsg_dump_get_buffer() can be called again and used multiple | |
4286 | * times within the same dumper.dump() callback. | |
4287 | */ | |
f9f3f02d | 4288 | void kmsg_dump_rewind(struct kmsg_dump_iter *iter) |
e2ae715d | 4289 | { |
a4f98765 JO |
4290 | iter->cur_seq = latched_seq_read_nolock(&clear_seq); |
4291 | iter->next_seq = prb_next_seq(prb); | |
456b565c | 4292 | } |
e2ae715d | 4293 | EXPORT_SYMBOL_GPL(kmsg_dump_rewind); |
196779b9 | 4294 | |
7ef3d2fd | 4295 | #endif |
766c268b JO |
4296 | |
4297 | #ifdef CONFIG_SMP | |
faebd693 JO |
4298 | static atomic_t printk_cpu_sync_owner = ATOMIC_INIT(-1); |
4299 | static atomic_t printk_cpu_sync_nested = ATOMIC_INIT(0); | |
766c268b JO |
4300 | |
4301 | /** | |
faebd693 JO |
4302 | * __printk_cpu_sync_wait() - Busy wait until the printk cpu-reentrant |
4303 | * spinning lock is not owned by any CPU. | |
766c268b JO |
4304 | * |
4305 | * Context: Any context. | |
4306 | */ | |
faebd693 | 4307 | void __printk_cpu_sync_wait(void) |
766c268b JO |
4308 | { |
4309 | do { | |
4310 | cpu_relax(); | |
faebd693 | 4311 | } while (atomic_read(&printk_cpu_sync_owner) != -1); |
766c268b | 4312 | } |
faebd693 | 4313 | EXPORT_SYMBOL(__printk_cpu_sync_wait); |
766c268b JO |
4314 | |
4315 | /** | |
faebd693 JO |
4316 | * __printk_cpu_sync_try_get() - Try to acquire the printk cpu-reentrant |
4317 | * spinning lock. | |
766c268b JO |
4318 | * |
4319 | * If no processor has the lock, the calling processor takes the lock and | |
4320 | * becomes the owner. If the calling processor is already the owner of the | |
4321 | * lock, this function succeeds immediately. | |
4322 | * | |
4323 | * Context: Any context. Expects interrupts to be disabled. | |
4324 | * Return: 1 on success, otherwise 0. | |
4325 | */ | |
faebd693 | 4326 | int __printk_cpu_sync_try_get(void) |
766c268b JO |
4327 | { |
4328 | int cpu; | |
4329 | int old; | |
4330 | ||
4331 | cpu = smp_processor_id(); | |
4332 | ||
3342aa8e JO |
4333 | /* |
4334 | * Guarantee loads and stores from this CPU when it is the lock owner | |
4335 | * are _not_ visible to the previous lock owner. This pairs with | |
faebd693 | 4336 | * __printk_cpu_sync_put:B. |
3342aa8e JO |
4337 | * |
4338 | * Memory barrier involvement: | |
4339 | * | |
faebd693 JO |
4340 | * If __printk_cpu_sync_try_get:A reads from __printk_cpu_sync_put:B, |
4341 | * then __printk_cpu_sync_put:A can never read from | |
4342 | * __printk_cpu_sync_try_get:B. | |
3342aa8e JO |
4343 | * |
4344 | * Relies on: | |
4345 | * | |
faebd693 | 4346 | * RELEASE from __printk_cpu_sync_put:A to __printk_cpu_sync_put:B |
3342aa8e JO |
4347 | * of the previous CPU |
4348 | * matching | |
faebd693 JO |
4349 | * ACQUIRE from __printk_cpu_sync_try_get:A to |
4350 | * __printk_cpu_sync_try_get:B of this CPU | |
3342aa8e | 4351 | */ |
faebd693 JO |
4352 | old = atomic_cmpxchg_acquire(&printk_cpu_sync_owner, -1, |
4353 | cpu); /* LMM(__printk_cpu_sync_try_get:A) */ | |
766c268b | 4354 | if (old == -1) { |
3342aa8e JO |
4355 | /* |
4356 | * This CPU is now the owner and begins loading/storing | |
faebd693 | 4357 | * data: LMM(__printk_cpu_sync_try_get:B) |
3342aa8e | 4358 | */ |
766c268b | 4359 | return 1; |
3342aa8e | 4360 | |
766c268b JO |
4361 | } else if (old == cpu) { |
4362 | /* This CPU is already the owner. */ | |
faebd693 | 4363 | atomic_inc(&printk_cpu_sync_nested); |
766c268b JO |
4364 | return 1; |
4365 | } | |
4366 | ||
4367 | return 0; | |
4368 | } | |
faebd693 | 4369 | EXPORT_SYMBOL(__printk_cpu_sync_try_get); |
766c268b JO |
4370 | |
4371 | /** | |
faebd693 | 4372 | * __printk_cpu_sync_put() - Release the printk cpu-reentrant spinning lock. |
766c268b JO |
4373 | * |
4374 | * The calling processor must be the owner of the lock. | |
4375 | * | |
4376 | * Context: Any context. Expects interrupts to be disabled. | |
4377 | */ | |
faebd693 | 4378 | void __printk_cpu_sync_put(void) |
766c268b | 4379 | { |
faebd693 JO |
4380 | if (atomic_read(&printk_cpu_sync_nested)) { |
4381 | atomic_dec(&printk_cpu_sync_nested); | |
766c268b JO |
4382 | return; |
4383 | } | |
4384 | ||
3342aa8e JO |
4385 | /* |
4386 | * This CPU is finished loading/storing data: | |
faebd693 | 4387 | * LMM(__printk_cpu_sync_put:A) |
3342aa8e JO |
4388 | */ |
4389 | ||
4390 | /* | |
4391 | * Guarantee loads and stores from this CPU when it was the | |
4392 | * lock owner are visible to the next lock owner. This pairs | |
faebd693 | 4393 | * with __printk_cpu_sync_try_get:A. |
3342aa8e JO |
4394 | * |
4395 | * Memory barrier involvement: | |
4396 | * | |
faebd693 JO |
4397 | * If __printk_cpu_sync_try_get:A reads from __printk_cpu_sync_put:B, |
4398 | * then __printk_cpu_sync_try_get:B reads from __printk_cpu_sync_put:A. | |
3342aa8e JO |
4399 | * |
4400 | * Relies on: | |
4401 | * | |
faebd693 | 4402 | * RELEASE from __printk_cpu_sync_put:A to __printk_cpu_sync_put:B |
3342aa8e JO |
4403 | * of this CPU |
4404 | * matching | |
faebd693 JO |
4405 | * ACQUIRE from __printk_cpu_sync_try_get:A to |
4406 | * __printk_cpu_sync_try_get:B of the next CPU | |
3342aa8e | 4407 | */ |
faebd693 JO |
4408 | atomic_set_release(&printk_cpu_sync_owner, |
4409 | -1); /* LMM(__printk_cpu_sync_put:B) */ | |
766c268b | 4410 | } |
faebd693 | 4411 | EXPORT_SYMBOL(__printk_cpu_sync_put); |
766c268b | 4412 | #endif /* CONFIG_SMP */ |