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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> |
d37d39ae | 38 | #include <linux/kdb.h> |
3fff4c42 | 39 | #include <linux/ratelimit.h> |
456b565c | 40 | #include <linux/kmsg_dump.h> |
00234592 | 41 | #include <linux/syslog.h> |
034260d6 | 42 | #include <linux/cpu.h> |
fb842b00 | 43 | #include <linux/rculist.h> |
e11fea92 | 44 | #include <linux/poll.h> |
74876a98 | 45 | #include <linux/irq_work.h> |
249771b8 | 46 | #include <linux/ctype.h> |
e2e40f2c | 47 | #include <linux/uio.h> |
e6017571 | 48 | #include <linux/sched/clock.h> |
b17b0153 | 49 | #include <linux/sched/debug.h> |
68db0cf1 | 50 | #include <linux/sched/task_stack.h> |
1da177e4 | 51 | |
7c0f6ba6 | 52 | #include <linux/uaccess.h> |
40a7d9f5 | 53 | #include <asm/sections.h> |
1da177e4 | 54 | |
58eacfff | 55 | #include <trace/events/initcall.h> |
95100358 JB |
56 | #define CREATE_TRACE_POINTS |
57 | #include <trace/events/printk.h> | |
58 | ||
d197c43d | 59 | #include "console_cmdline.h" |
bbeddf52 | 60 | #include "braille.h" |
42a0bb3f | 61 | #include "internal.h" |
d197c43d | 62 | |
1da177e4 | 63 | int console_printk[4] = { |
a8fe19eb | 64 | CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */ |
42a9dc0b | 65 | MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */ |
a8fe19eb BP |
66 | CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */ |
67 | CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ | |
1da177e4 | 68 | }; |
a1939185 | 69 | EXPORT_SYMBOL_GPL(console_printk); |
1da177e4 | 70 | |
56e6c104 TZ |
71 | atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0); |
72 | EXPORT_SYMBOL(ignore_console_lock_warning); | |
73 | ||
1da177e4 | 74 | /* |
0bbfb7c2 | 75 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
76 | * their unblank() callback or not. So let's export it. |
77 | */ | |
78 | int oops_in_progress; | |
79 | EXPORT_SYMBOL(oops_in_progress); | |
80 | ||
81 | /* | |
82 | * console_sem protects the console_drivers list, and also | |
83 | * provides serialisation for access to the entire console | |
84 | * driver system. | |
85 | */ | |
5b8c4f23 | 86 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 87 | struct console *console_drivers; |
a29d1cfe IM |
88 | EXPORT_SYMBOL_GPL(console_drivers); |
89 | ||
c39ea0b9 FT |
90 | /* |
91 | * System may need to suppress printk message under certain | |
92 | * circumstances, like after kernel panic happens. | |
93 | */ | |
94 | int __read_mostly suppress_printk; | |
95 | ||
daee7797 DV |
96 | #ifdef CONFIG_LOCKDEP |
97 | static struct lockdep_map console_lock_dep_map = { | |
98 | .name = "console_lock" | |
99 | }; | |
100 | #endif | |
101 | ||
750afe7b BP |
102 | enum devkmsg_log_bits { |
103 | __DEVKMSG_LOG_BIT_ON = 0, | |
104 | __DEVKMSG_LOG_BIT_OFF, | |
105 | __DEVKMSG_LOG_BIT_LOCK, | |
106 | }; | |
107 | ||
108 | enum devkmsg_log_masks { | |
109 | DEVKMSG_LOG_MASK_ON = BIT(__DEVKMSG_LOG_BIT_ON), | |
110 | DEVKMSG_LOG_MASK_OFF = BIT(__DEVKMSG_LOG_BIT_OFF), | |
111 | DEVKMSG_LOG_MASK_LOCK = BIT(__DEVKMSG_LOG_BIT_LOCK), | |
112 | }; | |
113 | ||
114 | /* Keep both the 'on' and 'off' bits clear, i.e. ratelimit by default: */ | |
115 | #define DEVKMSG_LOG_MASK_DEFAULT 0 | |
116 | ||
117 | static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; | |
118 | ||
119 | static int __control_devkmsg(char *str) | |
120 | { | |
121 | if (!str) | |
122 | return -EINVAL; | |
123 | ||
124 | if (!strncmp(str, "on", 2)) { | |
125 | devkmsg_log = DEVKMSG_LOG_MASK_ON; | |
126 | return 2; | |
127 | } else if (!strncmp(str, "off", 3)) { | |
128 | devkmsg_log = DEVKMSG_LOG_MASK_OFF; | |
129 | return 3; | |
130 | } else if (!strncmp(str, "ratelimit", 9)) { | |
131 | devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; | |
132 | return 9; | |
133 | } | |
134 | return -EINVAL; | |
135 | } | |
136 | ||
137 | static int __init control_devkmsg(char *str) | |
138 | { | |
139 | if (__control_devkmsg(str) < 0) | |
140 | return 1; | |
141 | ||
142 | /* | |
143 | * Set sysctl string accordingly: | |
144 | */ | |
6fd78a1a SS |
145 | if (devkmsg_log == DEVKMSG_LOG_MASK_ON) |
146 | strcpy(devkmsg_log_str, "on"); | |
147 | else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF) | |
148 | strcpy(devkmsg_log_str, "off"); | |
750afe7b BP |
149 | /* else "ratelimit" which is set by default. */ |
150 | ||
151 | /* | |
152 | * Sysctl cannot change it anymore. The kernel command line setting of | |
153 | * this parameter is to force the setting to be permanent throughout the | |
154 | * runtime of the system. This is a precation measure against userspace | |
155 | * trying to be a smarta** and attempting to change it up on us. | |
156 | */ | |
157 | devkmsg_log |= DEVKMSG_LOG_MASK_LOCK; | |
158 | ||
159 | return 0; | |
160 | } | |
161 | __setup("printk.devkmsg=", control_devkmsg); | |
162 | ||
163 | char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit"; | |
164 | ||
165 | int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, | |
166 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
167 | { | |
168 | char old_str[DEVKMSG_STR_MAX_SIZE]; | |
169 | unsigned int old; | |
170 | int err; | |
171 | ||
172 | if (write) { | |
173 | if (devkmsg_log & DEVKMSG_LOG_MASK_LOCK) | |
174 | return -EINVAL; | |
175 | ||
176 | old = devkmsg_log; | |
177 | strncpy(old_str, devkmsg_log_str, DEVKMSG_STR_MAX_SIZE); | |
178 | } | |
179 | ||
180 | err = proc_dostring(table, write, buffer, lenp, ppos); | |
181 | if (err) | |
182 | return err; | |
183 | ||
184 | if (write) { | |
185 | err = __control_devkmsg(devkmsg_log_str); | |
186 | ||
187 | /* | |
188 | * Do not accept an unknown string OR a known string with | |
189 | * trailing crap... | |
190 | */ | |
191 | if (err < 0 || (err + 1 != *lenp)) { | |
192 | ||
193 | /* ... and restore old setting. */ | |
194 | devkmsg_log = old; | |
195 | strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE); | |
196 | ||
197 | return -EINVAL; | |
198 | } | |
199 | } | |
200 | ||
201 | return 0; | |
202 | } | |
203 | ||
9627808d | 204 | /* Number of registered extended console drivers. */ |
6fe29354 TH |
205 | static int nr_ext_console_drivers; |
206 | ||
bd8d7cf5 JK |
207 | /* |
208 | * Helper macros to handle lockdep when locking/unlocking console_sem. We use | |
209 | * macros instead of functions so that _RET_IP_ contains useful information. | |
210 | */ | |
211 | #define down_console_sem() do { \ | |
212 | down(&console_sem);\ | |
213 | mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\ | |
214 | } while (0) | |
215 | ||
216 | static int __down_trylock_console_sem(unsigned long ip) | |
217 | { | |
f975237b SS |
218 | int lock_failed; |
219 | unsigned long flags; | |
220 | ||
221 | /* | |
222 | * Here and in __up_console_sem() we need to be in safe mode, | |
223 | * because spindump/WARN/etc from under console ->lock will | |
224 | * deadlock in printk()->down_trylock_console_sem() otherwise. | |
225 | */ | |
226 | printk_safe_enter_irqsave(flags); | |
227 | lock_failed = down_trylock(&console_sem); | |
228 | printk_safe_exit_irqrestore(flags); | |
229 | ||
230 | if (lock_failed) | |
bd8d7cf5 JK |
231 | return 1; |
232 | mutex_acquire(&console_lock_dep_map, 0, 1, ip); | |
233 | return 0; | |
234 | } | |
235 | #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) | |
236 | ||
f975237b SS |
237 | static void __up_console_sem(unsigned long ip) |
238 | { | |
239 | unsigned long flags; | |
240 | ||
241 | mutex_release(&console_lock_dep_map, 1, ip); | |
242 | ||
243 | printk_safe_enter_irqsave(flags); | |
244 | up(&console_sem); | |
245 | printk_safe_exit_irqrestore(flags); | |
246 | } | |
247 | #define up_console_sem() __up_console_sem(_RET_IP_) | |
bd8d7cf5 | 248 | |
1da177e4 LT |
249 | /* |
250 | * This is used for debugging the mess that is the VT code by | |
251 | * keeping track if we have the console semaphore held. It's | |
252 | * definitely not the perfect debug tool (we don't know if _WE_ | |
0b90fec3 AE |
253 | * hold it and are racing, but it helps tracking those weird code |
254 | * paths in the console code where we end up in places I want | |
255 | * locked without the console sempahore held). | |
1da177e4 | 256 | */ |
557240b4 | 257 | static int console_locked, console_suspended; |
1da177e4 | 258 | |
fe3d8ad3 FT |
259 | /* |
260 | * If exclusive_console is non-NULL then only this console is to be printed to. | |
261 | */ | |
262 | static struct console *exclusive_console; | |
263 | ||
1da177e4 LT |
264 | /* |
265 | * Array of consoles built from command line options (console=) | |
266 | */ | |
1da177e4 LT |
267 | |
268 | #define MAX_CMDLINECONSOLES 8 | |
269 | ||
270 | static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; | |
d197c43d | 271 | |
1da177e4 | 272 | static int preferred_console = -1; |
9e124fe1 MA |
273 | int console_set_on_cmdline; |
274 | EXPORT_SYMBOL(console_set_on_cmdline); | |
1da177e4 LT |
275 | |
276 | /* Flag: console code may call schedule() */ | |
277 | static int console_may_schedule; | |
278 | ||
cca10d58 SS |
279 | enum con_msg_format_flags { |
280 | MSG_FORMAT_DEFAULT = 0, | |
281 | MSG_FORMAT_SYSLOG = (1 << 0), | |
282 | }; | |
283 | ||
284 | static int console_msg_format = MSG_FORMAT_DEFAULT; | |
285 | ||
7ff9554b KS |
286 | /* |
287 | * The printk log buffer consists of a chain of concatenated variable | |
288 | * length records. Every record starts with a record header, containing | |
289 | * the overall length of the record. | |
290 | * | |
291 | * The heads to the first and last entry in the buffer, as well as the | |
0b90fec3 AE |
292 | * sequence numbers of these entries are maintained when messages are |
293 | * stored. | |
7ff9554b KS |
294 | * |
295 | * If the heads indicate available messages, the length in the header | |
296 | * tells the start next message. A length == 0 for the next message | |
297 | * indicates a wrap-around to the beginning of the buffer. | |
298 | * | |
299 | * Every record carries the monotonic timestamp in microseconds, as well as | |
300 | * the standard userspace syslog level and syslog facility. The usual | |
301 | * kernel messages use LOG_KERN; userspace-injected messages always carry | |
302 | * a matching syslog facility, by default LOG_USER. The origin of every | |
303 | * message can be reliably determined that way. | |
304 | * | |
305 | * The human readable log message directly follows the message header. The | |
306 | * length of the message text is stored in the header, the stored message | |
307 | * is not terminated. | |
308 | * | |
e11fea92 KS |
309 | * Optionally, a message can carry a dictionary of properties (key/value pairs), |
310 | * to provide userspace with a machine-readable message context. | |
311 | * | |
312 | * Examples for well-defined, commonly used property names are: | |
313 | * DEVICE=b12:8 device identifier | |
314 | * b12:8 block dev_t | |
315 | * c127:3 char dev_t | |
316 | * n8 netdev ifindex | |
317 | * +sound:card0 subsystem:devname | |
318 | * SUBSYSTEM=pci driver-core subsystem name | |
319 | * | |
320 | * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value | |
321 | * follows directly after a '=' character. Every property is terminated by | |
322 | * a '\0' character. The last property is not terminated. | |
323 | * | |
324 | * Example of a message structure: | |
325 | * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec | |
326 | * 0008 34 00 record is 52 bytes long | |
327 | * 000a 0b 00 text is 11 bytes long | |
328 | * 000c 1f 00 dictionary is 23 bytes long | |
329 | * 000e 03 00 LOG_KERN (facility) LOG_ERR (level) | |
330 | * 0010 69 74 27 73 20 61 20 6c "it's a l" | |
331 | * 69 6e 65 "ine" | |
332 | * 001b 44 45 56 49 43 "DEVIC" | |
333 | * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D" | |
334 | * 52 49 56 45 52 3d 62 75 "RIVER=bu" | |
335 | * 67 "g" | |
336 | * 0032 00 00 00 padding to next message header | |
337 | * | |
62e32ac3 | 338 | * The 'struct printk_log' buffer header must never be directly exported to |
e11fea92 KS |
339 | * userspace, it is a kernel-private implementation detail that might |
340 | * need to be changed in the future, when the requirements change. | |
341 | * | |
342 | * /dev/kmsg exports the structured data in the following line format: | |
b389645f AO |
343 | * "<level>,<sequnum>,<timestamp>,<contflag>[,additional_values, ... ];<message text>\n" |
344 | * | |
345 | * Users of the export format should ignore possible additional values | |
346 | * separated by ',', and find the message after the ';' character. | |
e11fea92 KS |
347 | * |
348 | * The optional key/value pairs are attached as continuation lines starting | |
349 | * with a space character and terminated by a newline. All possible | |
350 | * non-prinatable characters are escaped in the "\xff" notation. | |
7ff9554b KS |
351 | */ |
352 | ||
084681d1 | 353 | enum log_flags { |
5becfb1d | 354 | LOG_NEWLINE = 2, /* text ended with a newline */ |
5becfb1d | 355 | LOG_CONT = 8, /* text is a fragment of a continuation line */ |
084681d1 KS |
356 | }; |
357 | ||
62e32ac3 | 358 | struct printk_log { |
7ff9554b KS |
359 | u64 ts_nsec; /* timestamp in nanoseconds */ |
360 | u16 len; /* length of entire record */ | |
361 | u16 text_len; /* length of text buffer */ | |
362 | u16 dict_len; /* length of dictionary buffer */ | |
084681d1 KS |
363 | u8 facility; /* syslog facility */ |
364 | u8 flags:5; /* internal record flags */ | |
365 | u8 level:3; /* syslog level */ | |
15ff2069 TH |
366 | #ifdef CONFIG_PRINTK_CALLER |
367 | u32 caller_id; /* thread id or processor id */ | |
368 | #endif | |
5c9cf8af AR |
369 | } |
370 | #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS | |
371 | __packed __aligned(4) | |
372 | #endif | |
373 | ; | |
7ff9554b KS |
374 | |
375 | /* | |
458df9fd SR |
376 | * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken |
377 | * within the scheduler's rq lock. It must be released before calling | |
378 | * console_unlock() or anything else that might wake up a process. | |
7ff9554b | 379 | */ |
cf9b1106 | 380 | DEFINE_RAW_SPINLOCK(logbuf_lock); |
d59745ce | 381 | |
de6fcbdb SS |
382 | /* |
383 | * Helper macros to lock/unlock logbuf_lock and switch between | |
384 | * printk-safe/unsafe modes. | |
385 | */ | |
386 | #define logbuf_lock_irq() \ | |
387 | do { \ | |
388 | printk_safe_enter_irq(); \ | |
389 | raw_spin_lock(&logbuf_lock); \ | |
390 | } while (0) | |
391 | ||
392 | #define logbuf_unlock_irq() \ | |
393 | do { \ | |
394 | raw_spin_unlock(&logbuf_lock); \ | |
395 | printk_safe_exit_irq(); \ | |
396 | } while (0) | |
397 | ||
398 | #define logbuf_lock_irqsave(flags) \ | |
399 | do { \ | |
400 | printk_safe_enter_irqsave(flags); \ | |
401 | raw_spin_lock(&logbuf_lock); \ | |
402 | } while (0) | |
403 | ||
404 | #define logbuf_unlock_irqrestore(flags) \ | |
405 | do { \ | |
406 | raw_spin_unlock(&logbuf_lock); \ | |
407 | printk_safe_exit_irqrestore(flags); \ | |
408 | } while (0) | |
409 | ||
96efedf1 | 410 | #ifdef CONFIG_PRINTK |
dc72c32e | 411 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
7f3a781d KS |
412 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
413 | static u64 syslog_seq; | |
414 | static u32 syslog_idx; | |
eb02dac9 | 415 | static size_t syslog_partial; |
e80c1a9d | 416 | static bool syslog_time; |
7ff9554b KS |
417 | |
418 | /* index and sequence number of the first record stored in the buffer */ | |
419 | static u64 log_first_seq; | |
420 | static u32 log_first_idx; | |
421 | ||
422 | /* index and sequence number of the next record to store in the buffer */ | |
423 | static u64 log_next_seq; | |
424 | static u32 log_next_idx; | |
425 | ||
eab07260 KS |
426 | /* the next printk record to write to the console */ |
427 | static u64 console_seq; | |
428 | static u32 console_idx; | |
f92b070f | 429 | static u64 exclusive_console_stop_seq; |
eab07260 | 430 | |
7ff9554b KS |
431 | /* the next printk record to read after the last 'clear' command */ |
432 | static u64 clear_seq; | |
433 | static u32 clear_idx; | |
434 | ||
15ff2069 TH |
435 | #ifdef CONFIG_PRINTK_CALLER |
436 | #define PREFIX_MAX 48 | |
437 | #else | |
70498253 | 438 | #define PREFIX_MAX 32 |
15ff2069 | 439 | #endif |
249771b8 | 440 | #define LOG_LINE_MAX (1024 - PREFIX_MAX) |
7f3a781d | 441 | |
3824657c MK |
442 | #define LOG_LEVEL(v) ((v) & 0x07) |
443 | #define LOG_FACILITY(v) ((v) >> 3 & 0xff) | |
444 | ||
7f3a781d | 445 | /* record buffer */ |
62e32ac3 | 446 | #define LOG_ALIGN __alignof__(struct printk_log) |
7f3a781d | 447 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
e6fe3e5b | 448 | #define LOG_BUF_LEN_MAX (u32)(1 << 31) |
f8450fca | 449 | static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); |
7f3a781d KS |
450 | static char *log_buf = __log_buf; |
451 | static u32 log_buf_len = __LOG_BUF_LEN; | |
452 | ||
14c4000a VH |
453 | /* Return log buffer address */ |
454 | char *log_buf_addr_get(void) | |
455 | { | |
456 | return log_buf; | |
457 | } | |
458 | ||
459 | /* Return log buffer size */ | |
460 | u32 log_buf_len_get(void) | |
461 | { | |
462 | return log_buf_len; | |
463 | } | |
464 | ||
7ff9554b | 465 | /* human readable text of the record */ |
62e32ac3 | 466 | static char *log_text(const struct printk_log *msg) |
7ff9554b | 467 | { |
62e32ac3 | 468 | return (char *)msg + sizeof(struct printk_log); |
7ff9554b KS |
469 | } |
470 | ||
471 | /* optional key/value pair dictionary attached to the record */ | |
62e32ac3 | 472 | static char *log_dict(const struct printk_log *msg) |
7ff9554b | 473 | { |
62e32ac3 | 474 | return (char *)msg + sizeof(struct printk_log) + msg->text_len; |
7ff9554b KS |
475 | } |
476 | ||
477 | /* get record by index; idx must point to valid msg */ | |
62e32ac3 | 478 | static struct printk_log *log_from_idx(u32 idx) |
7ff9554b | 479 | { |
62e32ac3 | 480 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); |
7ff9554b KS |
481 | |
482 | /* | |
483 | * A length == 0 record is the end of buffer marker. Wrap around and | |
484 | * read the message at the start of the buffer. | |
485 | */ | |
486 | if (!msg->len) | |
62e32ac3 | 487 | return (struct printk_log *)log_buf; |
7ff9554b KS |
488 | return msg; |
489 | } | |
490 | ||
491 | /* get next record; idx must point to valid msg */ | |
492 | static u32 log_next(u32 idx) | |
493 | { | |
62e32ac3 | 494 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); |
7ff9554b KS |
495 | |
496 | /* length == 0 indicates the end of the buffer; wrap */ | |
497 | /* | |
498 | * A length == 0 record is the end of buffer marker. Wrap around and | |
499 | * read the message at the start of the buffer as *this* one, and | |
500 | * return the one after that. | |
501 | */ | |
502 | if (!msg->len) { | |
62e32ac3 | 503 | msg = (struct printk_log *)log_buf; |
7ff9554b KS |
504 | return msg->len; |
505 | } | |
506 | return idx + msg->len; | |
507 | } | |
508 | ||
f40e4b9f PM |
509 | /* |
510 | * Check whether there is enough free space for the given message. | |
511 | * | |
512 | * The same values of first_idx and next_idx mean that the buffer | |
513 | * is either empty or full. | |
514 | * | |
515 | * If the buffer is empty, we must respect the position of the indexes. | |
516 | * They cannot be reset to the beginning of the buffer. | |
517 | */ | |
518 | static int logbuf_has_space(u32 msg_size, bool empty) | |
0a581694 PM |
519 | { |
520 | u32 free; | |
521 | ||
f40e4b9f | 522 | if (log_next_idx > log_first_idx || empty) |
0a581694 PM |
523 | free = max(log_buf_len - log_next_idx, log_first_idx); |
524 | else | |
525 | free = log_first_idx - log_next_idx; | |
526 | ||
527 | /* | |
528 | * We need space also for an empty header that signalizes wrapping | |
529 | * of the buffer. | |
530 | */ | |
531 | return free >= msg_size + sizeof(struct printk_log); | |
532 | } | |
533 | ||
f40e4b9f | 534 | static int log_make_free_space(u32 msg_size) |
0a581694 | 535 | { |
f468908b ID |
536 | while (log_first_seq < log_next_seq && |
537 | !logbuf_has_space(msg_size, false)) { | |
0b90fec3 | 538 | /* drop old messages until we have enough contiguous space */ |
0a581694 PM |
539 | log_first_idx = log_next(log_first_idx); |
540 | log_first_seq++; | |
541 | } | |
f40e4b9f | 542 | |
f468908b ID |
543 | if (clear_seq < log_first_seq) { |
544 | clear_seq = log_first_seq; | |
545 | clear_idx = log_first_idx; | |
546 | } | |
547 | ||
f40e4b9f | 548 | /* sequence numbers are equal, so the log buffer is empty */ |
f468908b | 549 | if (logbuf_has_space(msg_size, log_first_seq == log_next_seq)) |
f40e4b9f PM |
550 | return 0; |
551 | ||
552 | return -ENOMEM; | |
0a581694 PM |
553 | } |
554 | ||
85c87043 PM |
555 | /* compute the message size including the padding bytes */ |
556 | static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len) | |
557 | { | |
558 | u32 size; | |
559 | ||
560 | size = sizeof(struct printk_log) + text_len + dict_len; | |
561 | *pad_len = (-size) & (LOG_ALIGN - 1); | |
562 | size += *pad_len; | |
563 | ||
564 | return size; | |
565 | } | |
566 | ||
55bd53a4 PM |
567 | /* |
568 | * Define how much of the log buffer we could take at maximum. The value | |
569 | * must be greater than two. Note that only half of the buffer is available | |
570 | * when the index points to the middle. | |
571 | */ | |
572 | #define MAX_LOG_TAKE_PART 4 | |
573 | static const char trunc_msg[] = "<truncated>"; | |
574 | ||
575 | static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len, | |
576 | u16 *dict_len, u32 *pad_len) | |
577 | { | |
578 | /* | |
579 | * The message should not take the whole buffer. Otherwise, it might | |
580 | * get removed too soon. | |
581 | */ | |
582 | u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART; | |
583 | if (*text_len > max_text_len) | |
584 | *text_len = max_text_len; | |
585 | /* enable the warning message */ | |
586 | *trunc_msg_len = strlen(trunc_msg); | |
587 | /* disable the "dict" completely */ | |
588 | *dict_len = 0; | |
589 | /* compute the size again, count also the warning message */ | |
590 | return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len); | |
591 | } | |
592 | ||
7ff9554b | 593 | /* insert record into the buffer, discard old ones, update heads */ |
cbae05d3 | 594 | static int log_store(u32 caller_id, int facility, int level, |
034633cc PM |
595 | enum log_flags flags, u64 ts_nsec, |
596 | const char *dict, u16 dict_len, | |
597 | const char *text, u16 text_len) | |
7ff9554b | 598 | { |
62e32ac3 | 599 | struct printk_log *msg; |
7ff9554b | 600 | u32 size, pad_len; |
55bd53a4 | 601 | u16 trunc_msg_len = 0; |
7ff9554b KS |
602 | |
603 | /* number of '\0' padding bytes to next message */ | |
85c87043 | 604 | size = msg_used_size(text_len, dict_len, &pad_len); |
7ff9554b | 605 | |
55bd53a4 PM |
606 | if (log_make_free_space(size)) { |
607 | /* truncate the message if it is too long for empty buffer */ | |
608 | size = truncate_msg(&text_len, &trunc_msg_len, | |
609 | &dict_len, &pad_len); | |
610 | /* survive when the log buffer is too small for trunc_msg */ | |
611 | if (log_make_free_space(size)) | |
034633cc | 612 | return 0; |
55bd53a4 | 613 | } |
7ff9554b | 614 | |
39b25109 | 615 | if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) { |
7ff9554b KS |
616 | /* |
617 | * This message + an additional empty header does not fit | |
618 | * at the end of the buffer. Add an empty header with len == 0 | |
619 | * to signify a wrap around. | |
620 | */ | |
62e32ac3 | 621 | memset(log_buf + log_next_idx, 0, sizeof(struct printk_log)); |
7ff9554b KS |
622 | log_next_idx = 0; |
623 | } | |
624 | ||
625 | /* fill message */ | |
62e32ac3 | 626 | msg = (struct printk_log *)(log_buf + log_next_idx); |
7ff9554b KS |
627 | memcpy(log_text(msg), text, text_len); |
628 | msg->text_len = text_len; | |
55bd53a4 PM |
629 | if (trunc_msg_len) { |
630 | memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len); | |
631 | msg->text_len += trunc_msg_len; | |
632 | } | |
7ff9554b KS |
633 | memcpy(log_dict(msg), dict, dict_len); |
634 | msg->dict_len = dict_len; | |
084681d1 KS |
635 | msg->facility = facility; |
636 | msg->level = level & 7; | |
637 | msg->flags = flags & 0x1f; | |
638 | if (ts_nsec > 0) | |
639 | msg->ts_nsec = ts_nsec; | |
640 | else | |
641 | msg->ts_nsec = local_clock(); | |
15ff2069 | 642 | #ifdef CONFIG_PRINTK_CALLER |
cbae05d3 | 643 | msg->caller_id = caller_id; |
15ff2069 | 644 | #endif |
7ff9554b | 645 | memset(log_dict(msg) + dict_len, 0, pad_len); |
fce6e033 | 646 | msg->len = size; |
7ff9554b KS |
647 | |
648 | /* insert message */ | |
649 | log_next_idx += msg->len; | |
650 | log_next_seq++; | |
034633cc PM |
651 | |
652 | return msg->text_len; | |
7ff9554b | 653 | } |
d59745ce | 654 | |
e99aa461 | 655 | int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); |
637241a9 KC |
656 | |
657 | static int syslog_action_restricted(int type) | |
658 | { | |
659 | if (dmesg_restrict) | |
660 | return 1; | |
661 | /* | |
662 | * Unless restricted, we allow "read all" and "get buffer size" | |
663 | * for everybody. | |
664 | */ | |
665 | return type != SYSLOG_ACTION_READ_ALL && | |
666 | type != SYSLOG_ACTION_SIZE_BUFFER; | |
667 | } | |
668 | ||
c71b02e4 | 669 | static int check_syslog_permissions(int type, int source) |
637241a9 KC |
670 | { |
671 | /* | |
672 | * If this is from /proc/kmsg and we've already opened it, then we've | |
673 | * already done the capabilities checks at open time. | |
674 | */ | |
3ea4331c | 675 | if (source == SYSLOG_FROM_PROC && type != SYSLOG_ACTION_OPEN) |
d194e5d6 | 676 | goto ok; |
637241a9 KC |
677 | |
678 | if (syslog_action_restricted(type)) { | |
679 | if (capable(CAP_SYSLOG)) | |
d194e5d6 | 680 | goto ok; |
637241a9 KC |
681 | /* |
682 | * For historical reasons, accept CAP_SYS_ADMIN too, with | |
683 | * a warning. | |
684 | */ | |
685 | if (capable(CAP_SYS_ADMIN)) { | |
686 | pr_warn_once("%s (%d): Attempt to access syslog with " | |
687 | "CAP_SYS_ADMIN but no CAP_SYSLOG " | |
688 | "(deprecated).\n", | |
689 | current->comm, task_pid_nr(current)); | |
d194e5d6 | 690 | goto ok; |
637241a9 KC |
691 | } |
692 | return -EPERM; | |
693 | } | |
d194e5d6 | 694 | ok: |
637241a9 KC |
695 | return security_syslog(type); |
696 | } | |
697 | ||
d43ff430 TH |
698 | static void append_char(char **pp, char *e, char c) |
699 | { | |
700 | if (*pp < e) | |
701 | *(*pp)++ = c; | |
702 | } | |
637241a9 | 703 | |
0a295e67 | 704 | static ssize_t msg_print_ext_header(char *buf, size_t size, |
5aa068ea | 705 | struct printk_log *msg, u64 seq) |
0a295e67 TH |
706 | { |
707 | u64 ts_usec = msg->ts_nsec; | |
15ff2069 TH |
708 | char caller[20]; |
709 | #ifdef CONFIG_PRINTK_CALLER | |
710 | u32 id = msg->caller_id; | |
711 | ||
712 | snprintf(caller, sizeof(caller), ",caller=%c%u", | |
713 | id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); | |
714 | #else | |
715 | caller[0] = '\0'; | |
716 | #endif | |
0a295e67 TH |
717 | |
718 | do_div(ts_usec, 1000); | |
719 | ||
15ff2069 TH |
720 | return scnprintf(buf, size, "%u,%llu,%llu,%c%s;", |
721 | (msg->facility << 3) | msg->level, seq, ts_usec, | |
722 | msg->flags & LOG_CONT ? 'c' : '-', caller); | |
0a295e67 TH |
723 | } |
724 | ||
725 | static ssize_t msg_print_ext_body(char *buf, size_t size, | |
726 | char *dict, size_t dict_len, | |
727 | char *text, size_t text_len) | |
728 | { | |
729 | char *p = buf, *e = buf + size; | |
730 | size_t i; | |
731 | ||
732 | /* escape non-printable characters */ | |
733 | for (i = 0; i < text_len; i++) { | |
734 | unsigned char c = text[i]; | |
735 | ||
736 | if (c < ' ' || c >= 127 || c == '\\') | |
737 | p += scnprintf(p, e - p, "\\x%02x", c); | |
738 | else | |
739 | append_char(&p, e, c); | |
740 | } | |
741 | append_char(&p, e, '\n'); | |
742 | ||
743 | if (dict_len) { | |
744 | bool line = true; | |
745 | ||
746 | for (i = 0; i < dict_len; i++) { | |
747 | unsigned char c = dict[i]; | |
748 | ||
749 | if (line) { | |
750 | append_char(&p, e, ' '); | |
751 | line = false; | |
752 | } | |
753 | ||
754 | if (c == '\0') { | |
755 | append_char(&p, e, '\n'); | |
756 | line = true; | |
757 | continue; | |
758 | } | |
759 | ||
760 | if (c < ' ' || c >= 127 || c == '\\') { | |
761 | p += scnprintf(p, e - p, "\\x%02x", c); | |
762 | continue; | |
763 | } | |
764 | ||
765 | append_char(&p, e, c); | |
766 | } | |
767 | append_char(&p, e, '\n'); | |
768 | } | |
769 | ||
770 | return p - buf; | |
771 | } | |
772 | ||
e11fea92 KS |
773 | /* /dev/kmsg - userspace message inject/listen interface */ |
774 | struct devkmsg_user { | |
775 | u64 seq; | |
776 | u32 idx; | |
750afe7b | 777 | struct ratelimit_state rs; |
e11fea92 | 778 | struct mutex lock; |
d43ff430 | 779 | char buf[CONSOLE_EXT_LOG_MAX]; |
e11fea92 KS |
780 | }; |
781 | ||
9adcfaff TH |
782 | static __printf(3, 4) __cold |
783 | int devkmsg_emit(int facility, int level, const char *fmt, ...) | |
784 | { | |
785 | va_list args; | |
786 | int r; | |
787 | ||
788 | va_start(args, fmt); | |
789 | r = vprintk_emit(facility, level, NULL, 0, fmt, args); | |
790 | va_end(args); | |
791 | ||
792 | return r; | |
793 | } | |
794 | ||
849f3127 | 795 | static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from) |
e11fea92 KS |
796 | { |
797 | char *buf, *line; | |
e11fea92 KS |
798 | int level = default_message_loglevel; |
799 | int facility = 1; /* LOG_USER */ | |
750afe7b BP |
800 | struct file *file = iocb->ki_filp; |
801 | struct devkmsg_user *user = file->private_data; | |
66ee59af | 802 | size_t len = iov_iter_count(from); |
e11fea92 KS |
803 | ssize_t ret = len; |
804 | ||
750afe7b | 805 | if (!user || len > LOG_LINE_MAX) |
e11fea92 | 806 | return -EINVAL; |
750afe7b BP |
807 | |
808 | /* Ignore when user logging is disabled. */ | |
809 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) | |
810 | return len; | |
811 | ||
812 | /* Ratelimit when not explicitly enabled. */ | |
813 | if (!(devkmsg_log & DEVKMSG_LOG_MASK_ON)) { | |
814 | if (!___ratelimit(&user->rs, current->comm)) | |
815 | return ret; | |
816 | } | |
817 | ||
e11fea92 KS |
818 | buf = kmalloc(len+1, GFP_KERNEL); |
819 | if (buf == NULL) | |
820 | return -ENOMEM; | |
821 | ||
849f3127 | 822 | buf[len] = '\0'; |
cbbd26b8 | 823 | if (!copy_from_iter_full(buf, len, from)) { |
849f3127 AV |
824 | kfree(buf); |
825 | return -EFAULT; | |
e11fea92 KS |
826 | } |
827 | ||
828 | /* | |
829 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace | |
830 | * the decimal value represents 32bit, the lower 3 bit are the log | |
831 | * level, the rest are the log facility. | |
832 | * | |
833 | * If no prefix or no userspace facility is specified, we | |
834 | * enforce LOG_USER, to be able to reliably distinguish | |
835 | * kernel-generated messages from userspace-injected ones. | |
836 | */ | |
837 | line = buf; | |
838 | if (line[0] == '<') { | |
839 | char *endp = NULL; | |
3824657c | 840 | unsigned int u; |
e11fea92 | 841 | |
3824657c | 842 | u = simple_strtoul(line + 1, &endp, 10); |
e11fea92 | 843 | if (endp && endp[0] == '>') { |
3824657c MK |
844 | level = LOG_LEVEL(u); |
845 | if (LOG_FACILITY(u) != 0) | |
846 | facility = LOG_FACILITY(u); | |
e11fea92 KS |
847 | endp++; |
848 | len -= endp - line; | |
849 | line = endp; | |
850 | } | |
851 | } | |
e11fea92 | 852 | |
9adcfaff | 853 | devkmsg_emit(facility, level, "%s", line); |
e11fea92 KS |
854 | kfree(buf); |
855 | return ret; | |
856 | } | |
857 | ||
858 | static ssize_t devkmsg_read(struct file *file, char __user *buf, | |
859 | size_t count, loff_t *ppos) | |
860 | { | |
861 | struct devkmsg_user *user = file->private_data; | |
62e32ac3 | 862 | struct printk_log *msg; |
e11fea92 KS |
863 | size_t len; |
864 | ssize_t ret; | |
865 | ||
866 | if (!user) | |
867 | return -EBADF; | |
868 | ||
4a77a5a0 YL |
869 | ret = mutex_lock_interruptible(&user->lock); |
870 | if (ret) | |
871 | return ret; | |
de6fcbdb SS |
872 | |
873 | logbuf_lock_irq(); | |
e11fea92 KS |
874 | while (user->seq == log_next_seq) { |
875 | if (file->f_flags & O_NONBLOCK) { | |
876 | ret = -EAGAIN; | |
de6fcbdb | 877 | logbuf_unlock_irq(); |
e11fea92 KS |
878 | goto out; |
879 | } | |
880 | ||
de6fcbdb | 881 | logbuf_unlock_irq(); |
e11fea92 KS |
882 | ret = wait_event_interruptible(log_wait, |
883 | user->seq != log_next_seq); | |
884 | if (ret) | |
885 | goto out; | |
de6fcbdb | 886 | logbuf_lock_irq(); |
e11fea92 KS |
887 | } |
888 | ||
889 | if (user->seq < log_first_seq) { | |
890 | /* our last seen message is gone, return error and reset */ | |
891 | user->idx = log_first_idx; | |
892 | user->seq = log_first_seq; | |
893 | ret = -EPIPE; | |
de6fcbdb | 894 | logbuf_unlock_irq(); |
e11fea92 KS |
895 | goto out; |
896 | } | |
897 | ||
898 | msg = log_from_idx(user->idx); | |
0a295e67 | 899 | len = msg_print_ext_header(user->buf, sizeof(user->buf), |
5aa068ea | 900 | msg, user->seq); |
0a295e67 TH |
901 | len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len, |
902 | log_dict(msg), msg->dict_len, | |
903 | log_text(msg), msg->text_len); | |
d39f3d77 | 904 | |
e11fea92 KS |
905 | user->idx = log_next(user->idx); |
906 | user->seq++; | |
de6fcbdb | 907 | logbuf_unlock_irq(); |
e11fea92 KS |
908 | |
909 | if (len > count) { | |
910 | ret = -EINVAL; | |
911 | goto out; | |
912 | } | |
913 | ||
914 | if (copy_to_user(buf, user->buf, len)) { | |
915 | ret = -EFAULT; | |
916 | goto out; | |
917 | } | |
918 | ret = len; | |
919 | out: | |
920 | mutex_unlock(&user->lock); | |
921 | return ret; | |
922 | } | |
923 | ||
924 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) | |
925 | { | |
926 | struct devkmsg_user *user = file->private_data; | |
927 | loff_t ret = 0; | |
928 | ||
929 | if (!user) | |
930 | return -EBADF; | |
931 | if (offset) | |
932 | return -ESPIPE; | |
933 | ||
de6fcbdb | 934 | logbuf_lock_irq(); |
e11fea92 KS |
935 | switch (whence) { |
936 | case SEEK_SET: | |
937 | /* the first record */ | |
938 | user->idx = log_first_idx; | |
939 | user->seq = log_first_seq; | |
940 | break; | |
941 | case SEEK_DATA: | |
942 | /* | |
943 | * The first record after the last SYSLOG_ACTION_CLEAR, | |
944 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself | |
945 | * changes no global state, and does not clear anything. | |
946 | */ | |
947 | user->idx = clear_idx; | |
948 | user->seq = clear_seq; | |
949 | break; | |
950 | case SEEK_END: | |
951 | /* after the last record */ | |
952 | user->idx = log_next_idx; | |
953 | user->seq = log_next_seq; | |
954 | break; | |
955 | default: | |
956 | ret = -EINVAL; | |
957 | } | |
de6fcbdb | 958 | logbuf_unlock_irq(); |
e11fea92 KS |
959 | return ret; |
960 | } | |
961 | ||
9dd95748 | 962 | static __poll_t devkmsg_poll(struct file *file, poll_table *wait) |
e11fea92 KS |
963 | { |
964 | struct devkmsg_user *user = file->private_data; | |
9dd95748 | 965 | __poll_t ret = 0; |
e11fea92 KS |
966 | |
967 | if (!user) | |
a9a08845 | 968 | return EPOLLERR|EPOLLNVAL; |
e11fea92 KS |
969 | |
970 | poll_wait(file, &log_wait, wait); | |
971 | ||
de6fcbdb | 972 | logbuf_lock_irq(); |
e11fea92 KS |
973 | if (user->seq < log_next_seq) { |
974 | /* return error when data has vanished underneath us */ | |
975 | if (user->seq < log_first_seq) | |
a9a08845 | 976 | ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI; |
0a285317 | 977 | else |
a9a08845 | 978 | ret = EPOLLIN|EPOLLRDNORM; |
e11fea92 | 979 | } |
de6fcbdb | 980 | logbuf_unlock_irq(); |
e11fea92 KS |
981 | |
982 | return ret; | |
983 | } | |
984 | ||
985 | static int devkmsg_open(struct inode *inode, struct file *file) | |
986 | { | |
987 | struct devkmsg_user *user; | |
988 | int err; | |
989 | ||
750afe7b BP |
990 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) |
991 | return -EPERM; | |
e11fea92 | 992 | |
750afe7b BP |
993 | /* write-only does not need any file context */ |
994 | if ((file->f_flags & O_ACCMODE) != O_WRONLY) { | |
995 | err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, | |
996 | SYSLOG_FROM_READER); | |
997 | if (err) | |
998 | return err; | |
999 | } | |
e11fea92 KS |
1000 | |
1001 | user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); | |
1002 | if (!user) | |
1003 | return -ENOMEM; | |
1004 | ||
750afe7b BP |
1005 | ratelimit_default_init(&user->rs); |
1006 | ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE); | |
1007 | ||
e11fea92 KS |
1008 | mutex_init(&user->lock); |
1009 | ||
de6fcbdb | 1010 | logbuf_lock_irq(); |
e11fea92 KS |
1011 | user->idx = log_first_idx; |
1012 | user->seq = log_first_seq; | |
de6fcbdb | 1013 | logbuf_unlock_irq(); |
e11fea92 KS |
1014 | |
1015 | file->private_data = user; | |
1016 | return 0; | |
1017 | } | |
1018 | ||
1019 | static int devkmsg_release(struct inode *inode, struct file *file) | |
1020 | { | |
1021 | struct devkmsg_user *user = file->private_data; | |
1022 | ||
1023 | if (!user) | |
1024 | return 0; | |
1025 | ||
750afe7b BP |
1026 | ratelimit_state_exit(&user->rs); |
1027 | ||
e11fea92 KS |
1028 | mutex_destroy(&user->lock); |
1029 | kfree(user); | |
1030 | return 0; | |
1031 | } | |
1032 | ||
1033 | const struct file_operations kmsg_fops = { | |
1034 | .open = devkmsg_open, | |
1035 | .read = devkmsg_read, | |
849f3127 | 1036 | .write_iter = devkmsg_write, |
e11fea92 KS |
1037 | .llseek = devkmsg_llseek, |
1038 | .poll = devkmsg_poll, | |
1039 | .release = devkmsg_release, | |
1040 | }; | |
1041 | ||
692f66f2 | 1042 | #ifdef CONFIG_CRASH_CORE |
04d491ab | 1043 | /* |
4c1ace64 | 1044 | * This appends the listed symbols to /proc/vmcore |
04d491ab | 1045 | * |
4c1ace64 | 1046 | * /proc/vmcore is used by various utilities, like crash and makedumpfile to |
04d491ab NH |
1047 | * obtain access to symbols that are otherwise very difficult to locate. These |
1048 | * symbols are specifically used so that utilities can access and extract the | |
1049 | * dmesg log from a vmcore file after a crash. | |
1050 | */ | |
692f66f2 | 1051 | void log_buf_vmcoreinfo_setup(void) |
04d491ab NH |
1052 | { |
1053 | VMCOREINFO_SYMBOL(log_buf); | |
04d491ab | 1054 | VMCOREINFO_SYMBOL(log_buf_len); |
7ff9554b | 1055 | VMCOREINFO_SYMBOL(log_first_idx); |
f468908b | 1056 | VMCOREINFO_SYMBOL(clear_idx); |
7ff9554b | 1057 | VMCOREINFO_SYMBOL(log_next_idx); |
6791457a | 1058 | /* |
62e32ac3 | 1059 | * Export struct printk_log size and field offsets. User space tools can |
6791457a VG |
1060 | * parse it and detect any changes to structure down the line. |
1061 | */ | |
62e32ac3 JP |
1062 | VMCOREINFO_STRUCT_SIZE(printk_log); |
1063 | VMCOREINFO_OFFSET(printk_log, ts_nsec); | |
1064 | VMCOREINFO_OFFSET(printk_log, len); | |
1065 | VMCOREINFO_OFFSET(printk_log, text_len); | |
1066 | VMCOREINFO_OFFSET(printk_log, dict_len); | |
15ff2069 TH |
1067 | #ifdef CONFIG_PRINTK_CALLER |
1068 | VMCOREINFO_OFFSET(printk_log, caller_id); | |
1069 | #endif | |
04d491ab NH |
1070 | } |
1071 | #endif | |
1072 | ||
162a7e75 MT |
1073 | /* requested log_buf_len from kernel cmdline */ |
1074 | static unsigned long __initdata new_log_buf_len; | |
1075 | ||
c0a318a3 | 1076 | /* we practice scaling the ring buffer by powers of 2 */ |
e6fe3e5b | 1077 | static void __init log_buf_len_update(u64 size) |
1da177e4 | 1078 | { |
e6fe3e5b HZ |
1079 | if (size > (u64)LOG_BUF_LEN_MAX) { |
1080 | size = (u64)LOG_BUF_LEN_MAX; | |
1081 | pr_err("log_buf over 2G is not supported.\n"); | |
1082 | } | |
1083 | ||
1da177e4 LT |
1084 | if (size) |
1085 | size = roundup_pow_of_two(size); | |
162a7e75 | 1086 | if (size > log_buf_len) |
e6fe3e5b | 1087 | new_log_buf_len = (unsigned long)size; |
c0a318a3 LR |
1088 | } |
1089 | ||
1090 | /* save requested log_buf_len since it's too early to process it */ | |
1091 | static int __init log_buf_len_setup(char *str) | |
1092 | { | |
e6fe3e5b | 1093 | u64 size; |
277fcdb2 HZ |
1094 | |
1095 | if (!str) | |
1096 | return -EINVAL; | |
1097 | ||
1098 | size = memparse(str, &str); | |
c0a318a3 LR |
1099 | |
1100 | log_buf_len_update(size); | |
162a7e75 MT |
1101 | |
1102 | return 0; | |
1da177e4 | 1103 | } |
162a7e75 MT |
1104 | early_param("log_buf_len", log_buf_len_setup); |
1105 | ||
2240a31d GU |
1106 | #ifdef CONFIG_SMP |
1107 | #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) | |
1108 | ||
23b2899f LR |
1109 | static void __init log_buf_add_cpu(void) |
1110 | { | |
1111 | unsigned int cpu_extra; | |
1112 | ||
1113 | /* | |
1114 | * archs should set up cpu_possible_bits properly with | |
1115 | * set_cpu_possible() after setup_arch() but just in | |
1116 | * case lets ensure this is valid. | |
1117 | */ | |
1118 | if (num_possible_cpus() == 1) | |
1119 | return; | |
1120 | ||
1121 | cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; | |
1122 | ||
1123 | /* by default this will only continue through for large > 64 CPUs */ | |
1124 | if (cpu_extra <= __LOG_BUF_LEN / 2) | |
1125 | return; | |
1126 | ||
1127 | pr_info("log_buf_len individual max cpu contribution: %d bytes\n", | |
1128 | __LOG_CPU_MAX_BUF_LEN); | |
1129 | pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", | |
1130 | cpu_extra); | |
1131 | pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); | |
1132 | ||
1133 | log_buf_len_update(cpu_extra + __LOG_BUF_LEN); | |
1134 | } | |
2240a31d GU |
1135 | #else /* !CONFIG_SMP */ |
1136 | static inline void log_buf_add_cpu(void) {} | |
1137 | #endif /* CONFIG_SMP */ | |
23b2899f | 1138 | |
162a7e75 MT |
1139 | void __init setup_log_buf(int early) |
1140 | { | |
1141 | unsigned long flags; | |
162a7e75 | 1142 | char *new_log_buf; |
d2130e82 | 1143 | unsigned int free; |
162a7e75 | 1144 | |
23b2899f LR |
1145 | if (log_buf != __log_buf) |
1146 | return; | |
1147 | ||
1148 | if (!early && !new_log_buf_len) | |
1149 | log_buf_add_cpu(); | |
1150 | ||
162a7e75 MT |
1151 | if (!new_log_buf_len) |
1152 | return; | |
1da177e4 | 1153 | |
26fb3dae | 1154 | new_log_buf = memblock_alloc(new_log_buf_len, LOG_ALIGN); |
162a7e75 | 1155 | if (unlikely(!new_log_buf)) { |
e6fe3e5b | 1156 | pr_err("log_buf_len: %lu bytes not available\n", |
162a7e75 MT |
1157 | new_log_buf_len); |
1158 | return; | |
1159 | } | |
1160 | ||
de6fcbdb | 1161 | logbuf_lock_irqsave(flags); |
162a7e75 MT |
1162 | log_buf_len = new_log_buf_len; |
1163 | log_buf = new_log_buf; | |
1164 | new_log_buf_len = 0; | |
7ff9554b KS |
1165 | free = __LOG_BUF_LEN - log_next_idx; |
1166 | memcpy(log_buf, __log_buf, __LOG_BUF_LEN); | |
de6fcbdb | 1167 | logbuf_unlock_irqrestore(flags); |
162a7e75 | 1168 | |
e6fe3e5b HZ |
1169 | pr_info("log_buf_len: %u bytes\n", log_buf_len); |
1170 | pr_info("early log buf free: %u(%u%%)\n", | |
162a7e75 MT |
1171 | free, (free * 100) / __LOG_BUF_LEN); |
1172 | } | |
1da177e4 | 1173 | |
2fa72c8f AC |
1174 | static bool __read_mostly ignore_loglevel; |
1175 | ||
1176 | static int __init ignore_loglevel_setup(char *str) | |
1177 | { | |
d25d9fec | 1178 | ignore_loglevel = true; |
27083bac | 1179 | pr_info("debug: ignoring loglevel setting.\n"); |
2fa72c8f AC |
1180 | |
1181 | return 0; | |
1182 | } | |
1183 | ||
1184 | early_param("ignore_loglevel", ignore_loglevel_setup); | |
1185 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); | |
205bd3d2 JP |
1186 | MODULE_PARM_DESC(ignore_loglevel, |
1187 | "ignore loglevel setting (prints all kernel messages to the console)"); | |
2fa72c8f | 1188 | |
cf775444 SS |
1189 | static bool suppress_message_printing(int level) |
1190 | { | |
1191 | return (level >= console_loglevel && !ignore_loglevel); | |
1192 | } | |
1193 | ||
bfe8df3d RD |
1194 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
1195 | ||
674dff65 | 1196 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 1197 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
1198 | |
1199 | static int __init boot_delay_setup(char *str) | |
1200 | { | |
1201 | unsigned long lpj; | |
bfe8df3d RD |
1202 | |
1203 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
1204 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
1205 | ||
1206 | get_option(&str, &boot_delay); | |
1207 | if (boot_delay > 10 * 1000) | |
1208 | boot_delay = 0; | |
1209 | ||
3a3b6ed2 DY |
1210 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
1211 | "HZ: %d, loops_per_msec: %llu\n", | |
1212 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
29e9d225 | 1213 | return 0; |
bfe8df3d | 1214 | } |
29e9d225 | 1215 | early_param("boot_delay", boot_delay_setup); |
bfe8df3d | 1216 | |
2fa72c8f | 1217 | static void boot_delay_msec(int level) |
bfe8df3d RD |
1218 | { |
1219 | unsigned long long k; | |
1220 | unsigned long timeout; | |
1221 | ||
ff48cd26 | 1222 | if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING) |
cf775444 | 1223 | || suppress_message_printing(level)) { |
bfe8df3d | 1224 | return; |
2fa72c8f | 1225 | } |
bfe8df3d | 1226 | |
3a3b6ed2 | 1227 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
1228 | |
1229 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
1230 | while (k) { | |
1231 | k--; | |
1232 | cpu_relax(); | |
1233 | /* | |
1234 | * use (volatile) jiffies to prevent | |
1235 | * compiler reduction; loop termination via jiffies | |
1236 | * is secondary and may or may not happen. | |
1237 | */ | |
1238 | if (time_after(jiffies, timeout)) | |
1239 | break; | |
1240 | touch_nmi_watchdog(); | |
1241 | } | |
1242 | } | |
1243 | #else | |
2fa72c8f | 1244 | static inline void boot_delay_msec(int level) |
bfe8df3d RD |
1245 | { |
1246 | } | |
1247 | #endif | |
1248 | ||
e99aa461 | 1249 | static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); |
7ff9554b KS |
1250 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1251 | ||
07c17732 | 1252 | static size_t print_syslog(unsigned int level, char *buf) |
084681d1 | 1253 | { |
07c17732 TH |
1254 | return sprintf(buf, "<%u>", level); |
1255 | } | |
35dac27c | 1256 | |
084681d1 KS |
1257 | static size_t print_time(u64 ts, char *buf) |
1258 | { | |
e80c1a9d | 1259 | unsigned long rem_nsec = do_div(ts, 1000000000); |
084681d1 | 1260 | |
15ff2069 | 1261 | return sprintf(buf, "[%5lu.%06lu]", |
084681d1 KS |
1262 | (unsigned long)ts, rem_nsec / 1000); |
1263 | } | |
1264 | ||
15ff2069 TH |
1265 | #ifdef CONFIG_PRINTK_CALLER |
1266 | static size_t print_caller(u32 id, char *buf) | |
1267 | { | |
1268 | char caller[12]; | |
1269 | ||
1270 | snprintf(caller, sizeof(caller), "%c%u", | |
1271 | id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); | |
1272 | return sprintf(buf, "[%6s]", caller); | |
1273 | } | |
1274 | #else | |
1275 | #define print_caller(id, buf) 0 | |
1276 | #endif | |
1277 | ||
e80c1a9d TH |
1278 | static size_t print_prefix(const struct printk_log *msg, bool syslog, |
1279 | bool time, char *buf) | |
649e6ee3 | 1280 | { |
3ce9a7c0 | 1281 | size_t len = 0; |
649e6ee3 | 1282 | |
07c17732 TH |
1283 | if (syslog) |
1284 | len = print_syslog((msg->facility << 3) | msg->level, buf); | |
15ff2069 | 1285 | |
e80c1a9d | 1286 | if (time) |
07c17732 | 1287 | len += print_time(msg->ts_nsec, buf + len); |
15ff2069 TH |
1288 | |
1289 | len += print_caller(msg->caller_id, buf + len); | |
1290 | ||
1291 | if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) { | |
1292 | buf[len++] = ' '; | |
1293 | buf[len] = '\0'; | |
1294 | } | |
1295 | ||
3ce9a7c0 | 1296 | return len; |
649e6ee3 KS |
1297 | } |
1298 | ||
e80c1a9d TH |
1299 | static size_t msg_print_text(const struct printk_log *msg, bool syslog, |
1300 | bool time, char *buf, size_t size) | |
7ff9554b | 1301 | { |
3ce9a7c0 KS |
1302 | const char *text = log_text(msg); |
1303 | size_t text_size = msg->text_len; | |
1304 | size_t len = 0; | |
07c17732 TH |
1305 | char prefix[PREFIX_MAX]; |
1306 | const size_t prefix_len = print_prefix(msg, syslog, time, prefix); | |
3ce9a7c0 KS |
1307 | |
1308 | do { | |
1309 | const char *next = memchr(text, '\n', text_size); | |
1310 | size_t text_len; | |
1311 | ||
1312 | if (next) { | |
1313 | text_len = next - text; | |
1314 | next++; | |
1315 | text_size -= next - text; | |
1316 | } else { | |
1317 | text_len = text_size; | |
1318 | } | |
7ff9554b | 1319 | |
3ce9a7c0 | 1320 | if (buf) { |
07c17732 | 1321 | if (prefix_len + text_len + 1 >= size - len) |
3ce9a7c0 | 1322 | break; |
7ff9554b | 1323 | |
07c17732 TH |
1324 | memcpy(buf + len, prefix, prefix_len); |
1325 | len += prefix_len; | |
3ce9a7c0 KS |
1326 | memcpy(buf + len, text, text_len); |
1327 | len += text_len; | |
5aa068ea | 1328 | buf[len++] = '\n'; |
3ce9a7c0 KS |
1329 | } else { |
1330 | /* SYSLOG_ACTION_* buffer size only calculation */ | |
07c17732 | 1331 | len += prefix_len + text_len + 1; |
3ce9a7c0 | 1332 | } |
7ff9554b | 1333 | |
3ce9a7c0 KS |
1334 | text = next; |
1335 | } while (text); | |
7ff9554b | 1336 | |
7ff9554b KS |
1337 | return len; |
1338 | } | |
1339 | ||
1340 | static int syslog_print(char __user *buf, int size) | |
1341 | { | |
1342 | char *text; | |
62e32ac3 | 1343 | struct printk_log *msg; |
116e90b2 | 1344 | int len = 0; |
7ff9554b | 1345 | |
70498253 | 1346 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
7ff9554b KS |
1347 | if (!text) |
1348 | return -ENOMEM; | |
1349 | ||
116e90b2 JB |
1350 | while (size > 0) { |
1351 | size_t n; | |
eb02dac9 | 1352 | size_t skip; |
116e90b2 | 1353 | |
de6fcbdb | 1354 | logbuf_lock_irq(); |
116e90b2 JB |
1355 | if (syslog_seq < log_first_seq) { |
1356 | /* messages are gone, move to first one */ | |
1357 | syslog_seq = log_first_seq; | |
1358 | syslog_idx = log_first_idx; | |
eb02dac9 | 1359 | syslog_partial = 0; |
116e90b2 JB |
1360 | } |
1361 | if (syslog_seq == log_next_seq) { | |
de6fcbdb | 1362 | logbuf_unlock_irq(); |
116e90b2 JB |
1363 | break; |
1364 | } | |
eb02dac9 | 1365 | |
e80c1a9d TH |
1366 | /* |
1367 | * To keep reading/counting partial line consistent, | |
1368 | * use printk_time value as of the beginning of a line. | |
1369 | */ | |
1370 | if (!syslog_partial) | |
1371 | syslog_time = printk_time; | |
1372 | ||
eb02dac9 | 1373 | skip = syslog_partial; |
116e90b2 | 1374 | msg = log_from_idx(syslog_idx); |
e80c1a9d TH |
1375 | n = msg_print_text(msg, true, syslog_time, text, |
1376 | LOG_LINE_MAX + PREFIX_MAX); | |
eb02dac9 KS |
1377 | if (n - syslog_partial <= size) { |
1378 | /* message fits into buffer, move forward */ | |
116e90b2 JB |
1379 | syslog_idx = log_next(syslog_idx); |
1380 | syslog_seq++; | |
eb02dac9 KS |
1381 | n -= syslog_partial; |
1382 | syslog_partial = 0; | |
1383 | } else if (!len){ | |
1384 | /* partial read(), remember position */ | |
1385 | n = size; | |
1386 | syslog_partial += n; | |
116e90b2 JB |
1387 | } else |
1388 | n = 0; | |
de6fcbdb | 1389 | logbuf_unlock_irq(); |
116e90b2 JB |
1390 | |
1391 | if (!n) | |
1392 | break; | |
1393 | ||
eb02dac9 | 1394 | if (copy_to_user(buf, text + skip, n)) { |
116e90b2 JB |
1395 | if (!len) |
1396 | len = -EFAULT; | |
1397 | break; | |
1398 | } | |
eb02dac9 KS |
1399 | |
1400 | len += n; | |
1401 | size -= n; | |
1402 | buf += n; | |
7ff9554b | 1403 | } |
7ff9554b KS |
1404 | |
1405 | kfree(text); | |
1406 | return len; | |
1407 | } | |
1408 | ||
1409 | static int syslog_print_all(char __user *buf, int size, bool clear) | |
1410 | { | |
1411 | char *text; | |
1412 | int len = 0; | |
63842c21 NG |
1413 | u64 next_seq; |
1414 | u64 seq; | |
1415 | u32 idx; | |
e80c1a9d | 1416 | bool time; |
63842c21 | 1417 | |
70498253 | 1418 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
7ff9554b KS |
1419 | if (!text) |
1420 | return -ENOMEM; | |
1421 | ||
e80c1a9d | 1422 | time = printk_time; |
de6fcbdb | 1423 | logbuf_lock_irq(); |
63842c21 NG |
1424 | /* |
1425 | * Find first record that fits, including all following records, | |
1426 | * into the user-provided buffer for this dump. | |
1427 | */ | |
1428 | seq = clear_seq; | |
1429 | idx = clear_idx; | |
1430 | while (seq < log_next_seq) { | |
1431 | struct printk_log *msg = log_from_idx(idx); | |
1432 | ||
e80c1a9d | 1433 | len += msg_print_text(msg, true, time, NULL, 0); |
63842c21 NG |
1434 | idx = log_next(idx); |
1435 | seq++; | |
1436 | } | |
e2ae715d | 1437 | |
63842c21 NG |
1438 | /* move first record forward until length fits into the buffer */ |
1439 | seq = clear_seq; | |
1440 | idx = clear_idx; | |
1441 | while (len > size && seq < log_next_seq) { | |
1442 | struct printk_log *msg = log_from_idx(idx); | |
3ce9a7c0 | 1443 | |
e80c1a9d | 1444 | len -= msg_print_text(msg, true, time, NULL, 0); |
63842c21 NG |
1445 | idx = log_next(idx); |
1446 | seq++; | |
1447 | } | |
7ff9554b | 1448 | |
63842c21 NG |
1449 | /* last message fitting into this dump */ |
1450 | next_seq = log_next_seq; | |
7ff9554b | 1451 | |
63842c21 NG |
1452 | len = 0; |
1453 | while (len >= 0 && seq < next_seq) { | |
1454 | struct printk_log *msg = log_from_idx(idx); | |
e80c1a9d TH |
1455 | int textlen = msg_print_text(msg, true, time, text, |
1456 | LOG_LINE_MAX + PREFIX_MAX); | |
7ff9554b | 1457 | |
63842c21 NG |
1458 | idx = log_next(idx); |
1459 | seq++; | |
7ff9554b | 1460 | |
63842c21 NG |
1461 | logbuf_unlock_irq(); |
1462 | if (copy_to_user(buf + len, text, textlen)) | |
1463 | len = -EFAULT; | |
1464 | else | |
1465 | len += textlen; | |
1466 | logbuf_lock_irq(); | |
7ff9554b | 1467 | |
63842c21 NG |
1468 | if (seq < log_first_seq) { |
1469 | /* messages are gone, move to next one */ | |
1470 | seq = log_first_seq; | |
1471 | idx = log_first_idx; | |
7ff9554b KS |
1472 | } |
1473 | } | |
1474 | ||
1475 | if (clear) { | |
1476 | clear_seq = log_next_seq; | |
1477 | clear_idx = log_next_idx; | |
1478 | } | |
de6fcbdb | 1479 | logbuf_unlock_irq(); |
7ff9554b KS |
1480 | |
1481 | kfree(text); | |
1482 | return len; | |
1483 | } | |
1484 | ||
8599dc7d PM |
1485 | static void syslog_clear(void) |
1486 | { | |
1487 | logbuf_lock_irq(); | |
1488 | clear_seq = log_next_seq; | |
1489 | clear_idx = log_next_idx; | |
1490 | logbuf_unlock_irq(); | |
1491 | } | |
1492 | ||
3ea4331c | 1493 | int do_syslog(int type, char __user *buf, int len, int source) |
1da177e4 | 1494 | { |
7ff9554b | 1495 | bool clear = false; |
a39d4a85 | 1496 | static int saved_console_loglevel = LOGLEVEL_DEFAULT; |
ee24aebf | 1497 | int error; |
1da177e4 | 1498 | |
3ea4331c | 1499 | error = check_syslog_permissions(type, source); |
ee24aebf | 1500 | if (error) |
077a1cc0 | 1501 | return error; |
12b3052c | 1502 | |
1da177e4 | 1503 | switch (type) { |
d78ca3cd | 1504 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 1505 | break; |
d78ca3cd | 1506 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 1507 | break; |
d78ca3cd | 1508 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 | 1509 | if (!buf || len < 0) |
077a1cc0 | 1510 | return -EINVAL; |
1da177e4 | 1511 | if (!len) |
077a1cc0 | 1512 | return 0; |
96d4f267 | 1513 | if (!access_ok(buf, len)) |
077a1cc0 | 1514 | return -EFAULT; |
40dc5651 | 1515 | error = wait_event_interruptible(log_wait, |
7ff9554b | 1516 | syslog_seq != log_next_seq); |
cb424ffe | 1517 | if (error) |
077a1cc0 | 1518 | return error; |
7ff9554b | 1519 | error = syslog_print(buf, len); |
1da177e4 | 1520 | break; |
d78ca3cd KC |
1521 | /* Read/clear last kernel messages */ |
1522 | case SYSLOG_ACTION_READ_CLEAR: | |
7ff9554b | 1523 | clear = true; |
1da177e4 | 1524 | /* FALL THRU */ |
d78ca3cd KC |
1525 | /* Read last kernel messages */ |
1526 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 | 1527 | if (!buf || len < 0) |
077a1cc0 | 1528 | return -EINVAL; |
1da177e4 | 1529 | if (!len) |
077a1cc0 | 1530 | return 0; |
96d4f267 | 1531 | if (!access_ok(buf, len)) |
077a1cc0 | 1532 | return -EFAULT; |
7ff9554b | 1533 | error = syslog_print_all(buf, len, clear); |
1da177e4 | 1534 | break; |
d78ca3cd KC |
1535 | /* Clear ring buffer */ |
1536 | case SYSLOG_ACTION_CLEAR: | |
8599dc7d | 1537 | syslog_clear(); |
4661e356 | 1538 | break; |
d78ca3cd KC |
1539 | /* Disable logging to console */ |
1540 | case SYSLOG_ACTION_CONSOLE_OFF: | |
a39d4a85 | 1541 | if (saved_console_loglevel == LOGLEVEL_DEFAULT) |
1aaad49e | 1542 | saved_console_loglevel = console_loglevel; |
1da177e4 LT |
1543 | console_loglevel = minimum_console_loglevel; |
1544 | break; | |
d78ca3cd KC |
1545 | /* Enable logging to console */ |
1546 | case SYSLOG_ACTION_CONSOLE_ON: | |
a39d4a85 | 1547 | if (saved_console_loglevel != LOGLEVEL_DEFAULT) { |
1aaad49e | 1548 | console_loglevel = saved_console_loglevel; |
a39d4a85 | 1549 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1aaad49e | 1550 | } |
1da177e4 | 1551 | break; |
d78ca3cd KC |
1552 | /* Set level of messages printed to console */ |
1553 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 | 1554 | if (len < 1 || len > 8) |
077a1cc0 | 1555 | return -EINVAL; |
1da177e4 LT |
1556 | if (len < minimum_console_loglevel) |
1557 | len = minimum_console_loglevel; | |
1558 | console_loglevel = len; | |
1aaad49e | 1559 | /* Implicitly re-enable logging to console */ |
a39d4a85 | 1560 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1da177e4 | 1561 | break; |
d78ca3cd KC |
1562 | /* Number of chars in the log buffer */ |
1563 | case SYSLOG_ACTION_SIZE_UNREAD: | |
de6fcbdb | 1564 | logbuf_lock_irq(); |
7ff9554b KS |
1565 | if (syslog_seq < log_first_seq) { |
1566 | /* messages are gone, move to first one */ | |
1567 | syslog_seq = log_first_seq; | |
1568 | syslog_idx = log_first_idx; | |
eb02dac9 | 1569 | syslog_partial = 0; |
7ff9554b | 1570 | } |
3ea4331c | 1571 | if (source == SYSLOG_FROM_PROC) { |
7ff9554b KS |
1572 | /* |
1573 | * Short-cut for poll(/"proc/kmsg") which simply checks | |
1574 | * for pending data, not the size; return the count of | |
1575 | * records, not the length. | |
1576 | */ | |
e97e1267 | 1577 | error = log_next_seq - syslog_seq; |
7ff9554b | 1578 | } else { |
5becfb1d KS |
1579 | u64 seq = syslog_seq; |
1580 | u32 idx = syslog_idx; | |
e80c1a9d | 1581 | bool time = syslog_partial ? syslog_time : printk_time; |
7ff9554b | 1582 | |
7ff9554b | 1583 | while (seq < log_next_seq) { |
62e32ac3 | 1584 | struct printk_log *msg = log_from_idx(idx); |
3ce9a7c0 | 1585 | |
e80c1a9d TH |
1586 | error += msg_print_text(msg, true, time, NULL, |
1587 | 0); | |
1588 | time = printk_time; | |
7ff9554b KS |
1589 | idx = log_next(idx); |
1590 | seq++; | |
1591 | } | |
eb02dac9 | 1592 | error -= syslog_partial; |
7ff9554b | 1593 | } |
de6fcbdb | 1594 | logbuf_unlock_irq(); |
1da177e4 | 1595 | break; |
d78ca3cd KC |
1596 | /* Size of the log buffer */ |
1597 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
1598 | error = log_buf_len; |
1599 | break; | |
1600 | default: | |
1601 | error = -EINVAL; | |
1602 | break; | |
1603 | } | |
077a1cc0 | 1604 | |
1da177e4 LT |
1605 | return error; |
1606 | } | |
1607 | ||
1e7bfb21 | 1608 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 1609 | { |
637241a9 | 1610 | return do_syslog(type, buf, len, SYSLOG_FROM_READER); |
1da177e4 LT |
1611 | } |
1612 | ||
c162d5b4 PM |
1613 | /* |
1614 | * Special console_lock variants that help to reduce the risk of soft-lockups. | |
1615 | * They allow to pass console_lock to another printk() call using a busy wait. | |
1616 | */ | |
1617 | ||
1618 | #ifdef CONFIG_LOCKDEP | |
1619 | static struct lockdep_map console_owner_dep_map = { | |
1620 | .name = "console_owner" | |
1621 | }; | |
1622 | #endif | |
1623 | ||
1624 | static DEFINE_RAW_SPINLOCK(console_owner_lock); | |
1625 | static struct task_struct *console_owner; | |
1626 | static bool console_waiter; | |
1627 | ||
1628 | /** | |
1629 | * console_lock_spinning_enable - mark beginning of code where another | |
1630 | * thread might safely busy wait | |
1631 | * | |
1632 | * This basically converts console_lock into a spinlock. This marks | |
1633 | * the section where the console_lock owner can not sleep, because | |
1634 | * there may be a waiter spinning (like a spinlock). Also it must be | |
1635 | * ready to hand over the lock at the end of the section. | |
1636 | */ | |
1637 | static void console_lock_spinning_enable(void) | |
1638 | { | |
1639 | raw_spin_lock(&console_owner_lock); | |
1640 | console_owner = current; | |
1641 | raw_spin_unlock(&console_owner_lock); | |
1642 | ||
1643 | /* The waiter may spin on us after setting console_owner */ | |
1644 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
1645 | } | |
1646 | ||
1647 | /** | |
1648 | * console_lock_spinning_disable_and_check - mark end of code where another | |
1649 | * thread was able to busy wait and check if there is a waiter | |
1650 | * | |
1651 | * This is called at the end of the section where spinning is allowed. | |
1652 | * It has two functions. First, it is a signal that it is no longer | |
1653 | * safe to start busy waiting for the lock. Second, it checks if | |
1654 | * there is a busy waiter and passes the lock rights to her. | |
1655 | * | |
1656 | * Important: Callers lose the lock if there was a busy waiter. | |
1657 | * They must not touch items synchronized by console_lock | |
1658 | * in this case. | |
1659 | * | |
1660 | * Return: 1 if the lock rights were passed, 0 otherwise. | |
1661 | */ | |
1662 | static int console_lock_spinning_disable_and_check(void) | |
1663 | { | |
1664 | int waiter; | |
1665 | ||
1666 | raw_spin_lock(&console_owner_lock); | |
1667 | waiter = READ_ONCE(console_waiter); | |
1668 | console_owner = NULL; | |
1669 | raw_spin_unlock(&console_owner_lock); | |
1670 | ||
1671 | if (!waiter) { | |
1672 | spin_release(&console_owner_dep_map, 1, _THIS_IP_); | |
1673 | return 0; | |
1674 | } | |
1675 | ||
1676 | /* The waiter is now free to continue */ | |
1677 | WRITE_ONCE(console_waiter, false); | |
1678 | ||
1679 | spin_release(&console_owner_dep_map, 1, _THIS_IP_); | |
1680 | ||
1681 | /* | |
1682 | * Hand off console_lock to waiter. The waiter will perform | |
1683 | * the up(). After this, the waiter is the console_lock owner. | |
1684 | */ | |
1685 | mutex_release(&console_lock_dep_map, 1, _THIS_IP_); | |
1686 | return 1; | |
1687 | } | |
1688 | ||
1689 | /** | |
1690 | * console_trylock_spinning - try to get console_lock by busy waiting | |
1691 | * | |
1692 | * This allows to busy wait for the console_lock when the current | |
1693 | * owner is running in specially marked sections. It means that | |
1694 | * the current owner is running and cannot reschedule until it | |
1695 | * is ready to lose the lock. | |
1696 | * | |
1697 | * Return: 1 if we got the lock, 0 othrewise | |
1698 | */ | |
1699 | static int console_trylock_spinning(void) | |
1700 | { | |
1701 | struct task_struct *owner = NULL; | |
1702 | bool waiter; | |
1703 | bool spin = false; | |
1704 | unsigned long flags; | |
1705 | ||
1706 | if (console_trylock()) | |
1707 | return 1; | |
1708 | ||
1709 | printk_safe_enter_irqsave(flags); | |
1710 | ||
1711 | raw_spin_lock(&console_owner_lock); | |
1712 | owner = READ_ONCE(console_owner); | |
1713 | waiter = READ_ONCE(console_waiter); | |
1714 | if (!waiter && owner && owner != current) { | |
1715 | WRITE_ONCE(console_waiter, true); | |
1716 | spin = true; | |
1717 | } | |
1718 | raw_spin_unlock(&console_owner_lock); | |
1719 | ||
1720 | /* | |
1721 | * If there is an active printk() writing to the | |
1722 | * consoles, instead of having it write our data too, | |
1723 | * see if we can offload that load from the active | |
1724 | * printer, and do some printing ourselves. | |
1725 | * Go into a spin only if there isn't already a waiter | |
1726 | * spinning, and there is an active printer, and | |
1727 | * that active printer isn't us (recursive printk?). | |
1728 | */ | |
1729 | if (!spin) { | |
1730 | printk_safe_exit_irqrestore(flags); | |
1731 | return 0; | |
1732 | } | |
1733 | ||
1734 | /* We spin waiting for the owner to release us */ | |
1735 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
1736 | /* Owner will clear console_waiter on hand off */ | |
1737 | while (READ_ONCE(console_waiter)) | |
1738 | cpu_relax(); | |
1739 | spin_release(&console_owner_dep_map, 1, _THIS_IP_); | |
1740 | ||
1741 | printk_safe_exit_irqrestore(flags); | |
1742 | /* | |
1743 | * The owner passed the console lock to us. | |
1744 | * Since we did not spin on console lock, annotate | |
1745 | * this as a trylock. Otherwise lockdep will | |
1746 | * complain. | |
1747 | */ | |
1748 | mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_); | |
1749 | ||
1750 | return 1; | |
1751 | } | |
1752 | ||
1da177e4 LT |
1753 | /* |
1754 | * Call the console drivers, asking them to write out | |
1755 | * log_buf[start] to log_buf[end - 1]. | |
ac751efa | 1756 | * The console_lock must be held. |
1da177e4 | 1757 | */ |
d9c23523 | 1758 | static void call_console_drivers(const char *ext_text, size_t ext_len, |
6fe29354 | 1759 | const char *text, size_t len) |
1da177e4 | 1760 | { |
7ff9554b | 1761 | struct console *con; |
1da177e4 | 1762 | |
fc98c3c8 | 1763 | trace_console_rcuidle(text, len); |
7ff9554b | 1764 | |
7ff9554b KS |
1765 | if (!console_drivers) |
1766 | return; | |
1767 | ||
1768 | for_each_console(con) { | |
1769 | if (exclusive_console && con != exclusive_console) | |
1770 | continue; | |
1771 | if (!(con->flags & CON_ENABLED)) | |
1772 | continue; | |
1773 | if (!con->write) | |
1774 | continue; | |
1775 | if (!cpu_online(smp_processor_id()) && | |
1776 | !(con->flags & CON_ANYTIME)) | |
1777 | continue; | |
6fe29354 TH |
1778 | if (con->flags & CON_EXTENDED) |
1779 | con->write(con, ext_text, ext_len); | |
1780 | else | |
1781 | con->write(con, text, len); | |
7ff9554b | 1782 | } |
1da177e4 LT |
1783 | } |
1784 | ||
af91322e DY |
1785 | int printk_delay_msec __read_mostly; |
1786 | ||
1787 | static inline void printk_delay(void) | |
1788 | { | |
1789 | if (unlikely(printk_delay_msec)) { | |
1790 | int m = printk_delay_msec; | |
1791 | ||
1792 | while (m--) { | |
1793 | mdelay(1); | |
1794 | touch_nmi_watchdog(); | |
1795 | } | |
1796 | } | |
1797 | } | |
1798 | ||
cbae05d3 TH |
1799 | static inline u32 printk_caller_id(void) |
1800 | { | |
1801 | return in_task() ? task_pid_nr(current) : | |
1802 | 0x80000000 + raw_smp_processor_id(); | |
1803 | } | |
1804 | ||
084681d1 KS |
1805 | /* |
1806 | * Continuation lines are buffered, and not committed to the record buffer | |
1807 | * until the line is complete, or a race forces it. The line fragments | |
1808 | * though, are printed immediately to the consoles to ensure everything has | |
1809 | * reached the console in case of a kernel crash. | |
1810 | */ | |
1811 | static struct cont { | |
1812 | char buf[LOG_LINE_MAX]; | |
1813 | size_t len; /* length == 0 means unused buffer */ | |
cbae05d3 | 1814 | u32 caller_id; /* printk_caller_id() of first print */ |
084681d1 KS |
1815 | u64 ts_nsec; /* time of first print */ |
1816 | u8 level; /* log level of first message */ | |
0b90fec3 | 1817 | u8 facility; /* log facility of first message */ |
eab07260 | 1818 | enum log_flags flags; /* prefix, newline flags */ |
084681d1 KS |
1819 | } cont; |
1820 | ||
5e467652 | 1821 | static void cont_flush(void) |
084681d1 | 1822 | { |
084681d1 KS |
1823 | if (cont.len == 0) |
1824 | return; | |
5c2992ee | 1825 | |
cbae05d3 TH |
1826 | log_store(cont.caller_id, cont.facility, cont.level, cont.flags, |
1827 | cont.ts_nsec, NULL, 0, cont.buf, cont.len); | |
5c2992ee | 1828 | cont.len = 0; |
084681d1 KS |
1829 | } |
1830 | ||
cbae05d3 TH |
1831 | static bool cont_add(u32 caller_id, int facility, int level, |
1832 | enum log_flags flags, const char *text, size_t len) | |
084681d1 | 1833 | { |
9627808d SS |
1834 | /* If the line gets too long, split it up in separate records. */ |
1835 | if (cont.len + len > sizeof(cont.buf)) { | |
5e467652 | 1836 | cont_flush(); |
084681d1 KS |
1837 | return false; |
1838 | } | |
1839 | ||
1840 | if (!cont.len) { | |
1841 | cont.facility = facility; | |
1842 | cont.level = level; | |
cbae05d3 | 1843 | cont.caller_id = caller_id; |
084681d1 | 1844 | cont.ts_nsec = local_clock(); |
5e467652 | 1845 | cont.flags = flags; |
084681d1 KS |
1846 | } |
1847 | ||
1848 | memcpy(cont.buf + cont.len, text, len); | |
1849 | cont.len += len; | |
eab07260 | 1850 | |
5e467652 LT |
1851 | // The original flags come from the first line, |
1852 | // but later continuations can add a newline. | |
1853 | if (flags & LOG_NEWLINE) { | |
1854 | cont.flags |= LOG_NEWLINE; | |
1855 | cont_flush(); | |
1856 | } | |
1857 | ||
084681d1 KS |
1858 | return true; |
1859 | } | |
1860 | ||
c362c7ff LT |
1861 | static size_t log_output(int facility, int level, enum log_flags lflags, const char *dict, size_t dictlen, char *text, size_t text_len) |
1862 | { | |
cbae05d3 TH |
1863 | const u32 caller_id = printk_caller_id(); |
1864 | ||
c362c7ff | 1865 | /* |
5e467652 | 1866 | * If an earlier line was buffered, and we're a continuation |
cbae05d3 | 1867 | * write from the same context, try to add it to the buffer. |
c362c7ff LT |
1868 | */ |
1869 | if (cont.len) { | |
cbae05d3 TH |
1870 | if (cont.caller_id == caller_id && (lflags & LOG_CONT)) { |
1871 | if (cont_add(caller_id, facility, level, lflags, text, text_len)) | |
5e467652 LT |
1872 | return text_len; |
1873 | } | |
1874 | /* Otherwise, make sure it's flushed */ | |
1875 | cont_flush(); | |
1876 | } | |
c362c7ff | 1877 | |
8835ca59 LT |
1878 | /* Skip empty continuation lines that couldn't be added - they just flush */ |
1879 | if (!text_len && (lflags & LOG_CONT)) | |
1880 | return 0; | |
1881 | ||
5e467652 LT |
1882 | /* If it doesn't end in a newline, try to buffer the current line */ |
1883 | if (!(lflags & LOG_NEWLINE)) { | |
cbae05d3 | 1884 | if (cont_add(caller_id, facility, level, lflags, text, text_len)) |
c362c7ff LT |
1885 | return text_len; |
1886 | } | |
1887 | ||
5e467652 | 1888 | /* Store it in the record log */ |
cbae05d3 TH |
1889 | return log_store(caller_id, facility, level, lflags, 0, |
1890 | dict, dictlen, text, text_len); | |
c362c7ff LT |
1891 | } |
1892 | ||
ba552399 PM |
1893 | /* Must be called under logbuf_lock. */ |
1894 | int vprintk_store(int facility, int level, | |
1895 | const char *dict, size_t dictlen, | |
1896 | const char *fmt, va_list args) | |
1da177e4 | 1897 | { |
7ff9554b KS |
1898 | static char textbuf[LOG_LINE_MAX]; |
1899 | char *text = textbuf; | |
aec47caa | 1900 | size_t text_len; |
5becfb1d | 1901 | enum log_flags lflags = 0; |
bfe8df3d | 1902 | |
7ff9554b KS |
1903 | /* |
1904 | * The printf needs to come first; we need the syslog | |
1905 | * prefix which might be passed-in as a parameter. | |
1906 | */ | |
98e35f58 | 1907 | text_len = vscnprintf(text, sizeof(textbuf), fmt, args); |
5fd29d6c | 1908 | |
7ff9554b | 1909 | /* mark and strip a trailing newline */ |
c313af14 KS |
1910 | if (text_len && text[text_len-1] == '\n') { |
1911 | text_len--; | |
5becfb1d | 1912 | lflags |= LOG_NEWLINE; |
7ff9554b | 1913 | } |
9d90c8d9 | 1914 | |
088a52aa JP |
1915 | /* strip kernel syslog prefix and extract log level or control flags */ |
1916 | if (facility == 0) { | |
4bcc595c | 1917 | int kern_level; |
088a52aa | 1918 | |
4bcc595c | 1919 | while ((kern_level = printk_get_level(text)) != 0) { |
088a52aa JP |
1920 | switch (kern_level) { |
1921 | case '0' ... '7': | |
a39d4a85 | 1922 | if (level == LOGLEVEL_DEFAULT) |
088a52aa | 1923 | level = kern_level - '0'; |
4bcc595c LT |
1924 | break; |
1925 | case 'c': /* KERN_CONT */ | |
1926 | lflags |= LOG_CONT; | |
088a52aa | 1927 | } |
4bcc595c LT |
1928 | |
1929 | text_len -= 2; | |
1930 | text += 2; | |
5fd29d6c LT |
1931 | } |
1932 | } | |
1933 | ||
a39d4a85 | 1934 | if (level == LOGLEVEL_DEFAULT) |
c313af14 | 1935 | level = default_message_loglevel; |
9d90c8d9 | 1936 | |
5becfb1d | 1937 | if (dict) |
e36202a8 | 1938 | lflags |= LOG_NEWLINE; |
ac60ad74 | 1939 | |
ba552399 PM |
1940 | return log_output(facility, level, lflags, |
1941 | dict, dictlen, text, text_len); | |
1942 | } | |
1da177e4 | 1943 | |
ba552399 PM |
1944 | asmlinkage int vprintk_emit(int facility, int level, |
1945 | const char *dict, size_t dictlen, | |
1946 | const char *fmt, va_list args) | |
1947 | { | |
1948 | int printed_len; | |
3ac37a93 | 1949 | bool in_sched = false, pending_output; |
ba552399 | 1950 | unsigned long flags; |
3ac37a93 | 1951 | u64 curr_log_seq; |
ba552399 | 1952 | |
c39ea0b9 FT |
1953 | /* Suppress unimportant messages after panic happens */ |
1954 | if (unlikely(suppress_printk)) | |
1955 | return 0; | |
1956 | ||
ba552399 PM |
1957 | if (level == LOGLEVEL_SCHED) { |
1958 | level = LOGLEVEL_DEFAULT; | |
1959 | in_sched = true; | |
1960 | } | |
1961 | ||
1962 | boot_delay_msec(level); | |
1963 | printk_delay(); | |
1964 | ||
1965 | /* This stops the holder of console_sem just where we want him */ | |
1966 | logbuf_lock_irqsave(flags); | |
3ac37a93 | 1967 | curr_log_seq = log_next_seq; |
ba552399 | 1968 | printed_len = vprintk_store(facility, level, dict, dictlen, fmt, args); |
3ac37a93 | 1969 | pending_output = (curr_log_seq != log_next_seq); |
de6fcbdb | 1970 | logbuf_unlock_irqrestore(flags); |
939f04be | 1971 | |
458df9fd | 1972 | /* If called from the scheduler, we can not call up(). */ |
3ac37a93 | 1973 | if (!in_sched && pending_output) { |
fd5f7cde SS |
1974 | /* |
1975 | * Disable preemption to avoid being preempted while holding | |
1976 | * console_sem which would prevent anyone from printing to | |
1977 | * console | |
1978 | */ | |
1979 | preempt_disable(); | |
d18bbc21 AM |
1980 | /* |
1981 | * Try to acquire and then immediately release the console | |
1982 | * semaphore. The release will print out buffers and wake up | |
1983 | * /dev/kmsg and syslog() users. | |
1984 | */ | |
c162d5b4 | 1985 | if (console_trylock_spinning()) |
d18bbc21 | 1986 | console_unlock(); |
fd5f7cde | 1987 | preempt_enable(); |
d18bbc21 | 1988 | } |
76a8ad29 | 1989 | |
3ac37a93 SS |
1990 | if (pending_output) |
1991 | wake_up_klogd(); | |
1da177e4 LT |
1992 | return printed_len; |
1993 | } | |
7ff9554b KS |
1994 | EXPORT_SYMBOL(vprintk_emit); |
1995 | ||
1996 | asmlinkage int vprintk(const char *fmt, va_list args) | |
1997 | { | |
bd66a892 | 1998 | return vprintk_func(fmt, args); |
7ff9554b | 1999 | } |
1da177e4 LT |
2000 | EXPORT_SYMBOL(vprintk); |
2001 | ||
a0cba217 | 2002 | int vprintk_default(const char *fmt, va_list args) |
afdc34a3 SRRH |
2003 | { |
2004 | int r; | |
2005 | ||
2006 | #ifdef CONFIG_KGDB_KDB | |
34aaff40 PM |
2007 | /* Allow to pass printk() to kdb but avoid a recursion. */ |
2008 | if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) { | |
f7d4ca8b | 2009 | r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args); |
afdc34a3 SRRH |
2010 | return r; |
2011 | } | |
2012 | #endif | |
a0cba217 | 2013 | r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); |
afdc34a3 SRRH |
2014 | |
2015 | return r; | |
2016 | } | |
2017 | EXPORT_SYMBOL_GPL(vprintk_default); | |
2018 | ||
7ff9554b KS |
2019 | /** |
2020 | * printk - print a kernel message | |
2021 | * @fmt: format string | |
2022 | * | |
2023 | * This is printk(). It can be called from any context. We want it to work. | |
2024 | * | |
2025 | * We try to grab the console_lock. If we succeed, it's easy - we log the | |
2026 | * output and call the console drivers. If we fail to get the semaphore, we | |
2027 | * place the output into the log buffer and return. The current holder of | |
2028 | * the console_sem will notice the new output in console_unlock(); and will | |
2029 | * send it to the consoles before releasing the lock. | |
2030 | * | |
2031 | * One effect of this deferred printing is that code which calls printk() and | |
2032 | * then changes console_loglevel may break. This is because console_loglevel | |
2033 | * is inspected when the actual printing occurs. | |
2034 | * | |
2035 | * See also: | |
2036 | * printf(3) | |
2037 | * | |
2038 | * See the vsnprintf() documentation for format string extensions over C99. | |
2039 | */ | |
722a9f92 | 2040 | asmlinkage __visible int printk(const char *fmt, ...) |
7ff9554b KS |
2041 | { |
2042 | va_list args; | |
2043 | int r; | |
2044 | ||
7ff9554b | 2045 | va_start(args, fmt); |
a0cba217 | 2046 | r = vprintk_func(fmt, args); |
7ff9554b KS |
2047 | va_end(args); |
2048 | ||
2049 | return r; | |
2050 | } | |
2051 | EXPORT_SYMBOL(printk); | |
7f3a781d | 2052 | |
96efedf1 | 2053 | #else /* CONFIG_PRINTK */ |
d59745ce | 2054 | |
70498253 KS |
2055 | #define LOG_LINE_MAX 0 |
2056 | #define PREFIX_MAX 0 | |
e80c1a9d | 2057 | #define printk_time false |
249771b8 | 2058 | |
96efedf1 KS |
2059 | static u64 syslog_seq; |
2060 | static u32 syslog_idx; | |
eab07260 KS |
2061 | static u64 console_seq; |
2062 | static u32 console_idx; | |
f92b070f | 2063 | static u64 exclusive_console_stop_seq; |
96efedf1 KS |
2064 | static u64 log_first_seq; |
2065 | static u32 log_first_idx; | |
2066 | static u64 log_next_seq; | |
6fe29354 TH |
2067 | static char *log_text(const struct printk_log *msg) { return NULL; } |
2068 | static char *log_dict(const struct printk_log *msg) { return NULL; } | |
62e32ac3 | 2069 | static struct printk_log *log_from_idx(u32 idx) { return NULL; } |
7f3a781d | 2070 | static u32 log_next(u32 idx) { return 0; } |
6fe29354 | 2071 | static ssize_t msg_print_ext_header(char *buf, size_t size, |
5aa068ea LT |
2072 | struct printk_log *msg, |
2073 | u64 seq) { return 0; } | |
6fe29354 TH |
2074 | static ssize_t msg_print_ext_body(char *buf, size_t size, |
2075 | char *dict, size_t dict_len, | |
2076 | char *text, size_t text_len) { return 0; } | |
c162d5b4 PM |
2077 | static void console_lock_spinning_enable(void) { } |
2078 | static int console_lock_spinning_disable_and_check(void) { return 0; } | |
d9c23523 | 2079 | static void call_console_drivers(const char *ext_text, size_t ext_len, |
6fe29354 | 2080 | const char *text, size_t len) {} |
e80c1a9d TH |
2081 | static size_t msg_print_text(const struct printk_log *msg, bool syslog, |
2082 | bool time, char *buf, size_t size) { return 0; } | |
a6ae928c | 2083 | static bool suppress_message_printing(int level) { return false; } |
d59745ce | 2084 | |
7f3a781d | 2085 | #endif /* CONFIG_PRINTK */ |
d59745ce | 2086 | |
d0380e6c TG |
2087 | #ifdef CONFIG_EARLY_PRINTK |
2088 | struct console *early_console; | |
2089 | ||
722a9f92 | 2090 | asmlinkage __visible void early_printk(const char *fmt, ...) |
d0380e6c TG |
2091 | { |
2092 | va_list ap; | |
1dc6244b JP |
2093 | char buf[512]; |
2094 | int n; | |
2095 | ||
2096 | if (!early_console) | |
2097 | return; | |
d0380e6c TG |
2098 | |
2099 | va_start(ap, fmt); | |
1dc6244b | 2100 | n = vscnprintf(buf, sizeof(buf), fmt, ap); |
d0380e6c | 2101 | va_end(ap); |
1dc6244b JP |
2102 | |
2103 | early_console->write(early_console, buf, n); | |
d0380e6c TG |
2104 | } |
2105 | #endif | |
2106 | ||
f7511d5f ST |
2107 | static int __add_preferred_console(char *name, int idx, char *options, |
2108 | char *brl_options) | |
2109 | { | |
2110 | struct console_cmdline *c; | |
2111 | int i; | |
2112 | ||
2113 | /* | |
2114 | * See if this tty is not yet registered, and | |
2115 | * if we have a slot free. | |
2116 | */ | |
dac8bbba PM |
2117 | for (i = 0, c = console_cmdline; |
2118 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2119 | i++, c++) { | |
23475408 | 2120 | if (strcmp(c->name, name) == 0 && c->index == idx) { |
dac8bbba PM |
2121 | if (!brl_options) |
2122 | preferred_console = i; | |
23475408 | 2123 | return 0; |
f7511d5f | 2124 | } |
23475408 | 2125 | } |
f7511d5f ST |
2126 | if (i == MAX_CMDLINECONSOLES) |
2127 | return -E2BIG; | |
2128 | if (!brl_options) | |
ad86ee2b | 2129 | preferred_console = i; |
f7511d5f ST |
2130 | strlcpy(c->name, name, sizeof(c->name)); |
2131 | c->options = options; | |
bbeddf52 JP |
2132 | braille_set_options(c, brl_options); |
2133 | ||
f7511d5f ST |
2134 | c->index = idx; |
2135 | return 0; | |
2136 | } | |
cca10d58 SS |
2137 | |
2138 | static int __init console_msg_format_setup(char *str) | |
2139 | { | |
2140 | if (!strcmp(str, "syslog")) | |
2141 | console_msg_format = MSG_FORMAT_SYSLOG; | |
2142 | if (!strcmp(str, "default")) | |
2143 | console_msg_format = MSG_FORMAT_DEFAULT; | |
2144 | return 1; | |
2145 | } | |
2146 | __setup("console_msg_format=", console_msg_format_setup); | |
2147 | ||
2ea1c539 | 2148 | /* |
0b90fec3 AE |
2149 | * Set up a console. Called via do_early_param() in init/main.c |
2150 | * for each "console=" parameter in the boot command line. | |
2ea1c539 JB |
2151 | */ |
2152 | static int __init console_setup(char *str) | |
2153 | { | |
0b90fec3 | 2154 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ |
f7511d5f | 2155 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
2156 | int idx; |
2157 | ||
bbeddf52 JP |
2158 | if (_braille_console_setup(&str, &brl_options)) |
2159 | return 1; | |
f7511d5f | 2160 | |
2ea1c539 JB |
2161 | /* |
2162 | * Decode str into name, index, options. | |
2163 | */ | |
2164 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
2165 | strcpy(buf, "ttyS"); |
2166 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 2167 | } else { |
eaa944af | 2168 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 2169 | } |
eaa944af | 2170 | buf[sizeof(buf) - 1] = 0; |
249771b8 AE |
2171 | options = strchr(str, ','); |
2172 | if (options) | |
2ea1c539 JB |
2173 | *(options++) = 0; |
2174 | #ifdef __sparc__ | |
2175 | if (!strcmp(str, "ttya")) | |
eaa944af | 2176 | strcpy(buf, "ttyS0"); |
2ea1c539 | 2177 | if (!strcmp(str, "ttyb")) |
eaa944af | 2178 | strcpy(buf, "ttyS1"); |
2ea1c539 | 2179 | #endif |
eaa944af | 2180 | for (s = buf; *s; s++) |
249771b8 | 2181 | if (isdigit(*s) || *s == ',') |
2ea1c539 JB |
2182 | break; |
2183 | idx = simple_strtoul(s, NULL, 10); | |
2184 | *s = 0; | |
2185 | ||
f7511d5f | 2186 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 2187 | console_set_on_cmdline = 1; |
2ea1c539 JB |
2188 | return 1; |
2189 | } | |
2190 | __setup("console=", console_setup); | |
2191 | ||
3c0547ba MM |
2192 | /** |
2193 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
2194 | * @name: device name |
2195 | * @idx: device index | |
2196 | * @options: options for this console | |
3c0547ba MM |
2197 | * |
2198 | * The last preferred console added will be used for kernel messages | |
2199 | * and stdin/out/err for init. Normally this is used by console_setup | |
2200 | * above to handle user-supplied console arguments; however it can also | |
2201 | * be used by arch-specific code either to override the user or more | |
2202 | * commonly to provide a default console (ie from PROM variables) when | |
2203 | * the user has not supplied one. | |
2204 | */ | |
fb445ee5 | 2205 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 2206 | { |
f7511d5f | 2207 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
2208 | } |
2209 | ||
d25d9fec | 2210 | bool console_suspend_enabled = true; |
8f4ce8c3 AS |
2211 | EXPORT_SYMBOL(console_suspend_enabled); |
2212 | ||
2213 | static int __init console_suspend_disable(char *str) | |
2214 | { | |
d25d9fec | 2215 | console_suspend_enabled = false; |
8f4ce8c3 AS |
2216 | return 1; |
2217 | } | |
2218 | __setup("no_console_suspend", console_suspend_disable); | |
134620f7 YZ |
2219 | module_param_named(console_suspend, console_suspend_enabled, |
2220 | bool, S_IRUGO | S_IWUSR); | |
2221 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" | |
2222 | " and hibernate operations"); | |
8f4ce8c3 | 2223 | |
557240b4 LT |
2224 | /** |
2225 | * suspend_console - suspend the console subsystem | |
2226 | * | |
2227 | * This disables printk() while we go into suspend states | |
2228 | */ | |
2229 | void suspend_console(void) | |
2230 | { | |
8f4ce8c3 AS |
2231 | if (!console_suspend_enabled) |
2232 | return; | |
47319f71 | 2233 | pr_info("Suspending console(s) (use no_console_suspend to debug)\n"); |
ac751efa | 2234 | console_lock(); |
557240b4 | 2235 | console_suspended = 1; |
bd8d7cf5 | 2236 | up_console_sem(); |
557240b4 LT |
2237 | } |
2238 | ||
2239 | void resume_console(void) | |
2240 | { | |
8f4ce8c3 AS |
2241 | if (!console_suspend_enabled) |
2242 | return; | |
bd8d7cf5 | 2243 | down_console_sem(); |
557240b4 | 2244 | console_suspended = 0; |
ac751efa | 2245 | console_unlock(); |
557240b4 LT |
2246 | } |
2247 | ||
034260d6 KC |
2248 | /** |
2249 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
90b14889 | 2250 | * @cpu: unused |
034260d6 KC |
2251 | * |
2252 | * If printk() is called from a CPU that is not online yet, the messages | |
64ca752d SS |
2253 | * will be printed on the console only if there are CON_ANYTIME consoles. |
2254 | * This function is called when a new CPU comes online (or fails to come | |
2255 | * up) or goes offline. | |
034260d6 | 2256 | */ |
90b14889 SAS |
2257 | static int console_cpu_notify(unsigned int cpu) |
2258 | { | |
f97960fb | 2259 | if (!cpuhp_tasks_frozen) { |
64ca752d SS |
2260 | /* If trylock fails, someone else is doing the printing */ |
2261 | if (console_trylock()) | |
2262 | console_unlock(); | |
034260d6 | 2263 | } |
90b14889 | 2264 | return 0; |
034260d6 KC |
2265 | } |
2266 | ||
1da177e4 | 2267 | /** |
ac751efa | 2268 | * console_lock - lock the console system for exclusive use. |
1da177e4 | 2269 | * |
ac751efa | 2270 | * Acquires a lock which guarantees that the caller has |
1da177e4 LT |
2271 | * exclusive access to the console system and the console_drivers list. |
2272 | * | |
2273 | * Can sleep, returns nothing. | |
2274 | */ | |
ac751efa | 2275 | void console_lock(void) |
1da177e4 | 2276 | { |
6b898c07 DV |
2277 | might_sleep(); |
2278 | ||
bd8d7cf5 | 2279 | down_console_sem(); |
403f3075 AH |
2280 | if (console_suspended) |
2281 | return; | |
1da177e4 LT |
2282 | console_locked = 1; |
2283 | console_may_schedule = 1; | |
2284 | } | |
ac751efa | 2285 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 2286 | |
ac751efa TH |
2287 | /** |
2288 | * console_trylock - try to lock the console system for exclusive use. | |
2289 | * | |
0b90fec3 AE |
2290 | * Try to acquire a lock which guarantees that the caller has exclusive |
2291 | * access to the console system and the console_drivers list. | |
ac751efa TH |
2292 | * |
2293 | * returns 1 on success, and 0 on failure to acquire the lock. | |
2294 | */ | |
2295 | int console_trylock(void) | |
1da177e4 | 2296 | { |
bd8d7cf5 | 2297 | if (down_trylock_console_sem()) |
ac751efa | 2298 | return 0; |
403f3075 | 2299 | if (console_suspended) { |
bd8d7cf5 | 2300 | up_console_sem(); |
ac751efa | 2301 | return 0; |
403f3075 | 2302 | } |
1da177e4 | 2303 | console_locked = 1; |
fd5f7cde | 2304 | console_may_schedule = 0; |
ac751efa | 2305 | return 1; |
1da177e4 | 2306 | } |
ac751efa | 2307 | EXPORT_SYMBOL(console_trylock); |
1da177e4 LT |
2308 | |
2309 | int is_console_locked(void) | |
2310 | { | |
2311 | return console_locked; | |
2312 | } | |
d48de54a | 2313 | EXPORT_SYMBOL(is_console_locked); |
1da177e4 | 2314 | |
a8199371 SS |
2315 | /* |
2316 | * Check if we have any console that is capable of printing while cpu is | |
2317 | * booting or shutting down. Requires console_sem. | |
2318 | */ | |
2319 | static int have_callable_console(void) | |
2320 | { | |
2321 | struct console *con; | |
2322 | ||
2323 | for_each_console(con) | |
adaf6590 SS |
2324 | if ((con->flags & CON_ENABLED) && |
2325 | (con->flags & CON_ANYTIME)) | |
a8199371 SS |
2326 | return 1; |
2327 | ||
2328 | return 0; | |
2329 | } | |
2330 | ||
2331 | /* | |
2332 | * Can we actually use the console at this time on this cpu? | |
2333 | * | |
2334 | * Console drivers may assume that per-cpu resources have been allocated. So | |
2335 | * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't | |
2336 | * call them until this CPU is officially up. | |
2337 | */ | |
2338 | static inline int can_use_console(void) | |
2339 | { | |
2340 | return cpu_online(raw_smp_processor_id()) || have_callable_console(); | |
2341 | } | |
2342 | ||
1da177e4 | 2343 | /** |
ac751efa | 2344 | * console_unlock - unlock the console system |
1da177e4 | 2345 | * |
ac751efa | 2346 | * Releases the console_lock which the caller holds on the console system |
1da177e4 LT |
2347 | * and the console driver list. |
2348 | * | |
ac751efa TH |
2349 | * While the console_lock was held, console output may have been buffered |
2350 | * by printk(). If this is the case, console_unlock(); emits | |
2351 | * the output prior to releasing the lock. | |
1da177e4 | 2352 | * |
7f3a781d | 2353 | * If there is output waiting, we wake /dev/kmsg and syslog() users. |
1da177e4 | 2354 | * |
ac751efa | 2355 | * console_unlock(); may be called from any context. |
1da177e4 | 2356 | */ |
ac751efa | 2357 | void console_unlock(void) |
1da177e4 | 2358 | { |
6fe29354 | 2359 | static char ext_text[CONSOLE_EXT_LOG_MAX]; |
70498253 | 2360 | static char text[LOG_LINE_MAX + PREFIX_MAX]; |
1da177e4 | 2361 | unsigned long flags; |
8d91f8b1 | 2362 | bool do_cond_resched, retry; |
1da177e4 | 2363 | |
557240b4 | 2364 | if (console_suspended) { |
bd8d7cf5 | 2365 | up_console_sem(); |
557240b4 LT |
2366 | return; |
2367 | } | |
78944e54 | 2368 | |
8d91f8b1 | 2369 | /* |
257ab443 | 2370 | * Console drivers are called with interrupts disabled, so |
8d91f8b1 TH |
2371 | * @console_may_schedule should be cleared before; however, we may |
2372 | * end up dumping a lot of lines, for example, if called from | |
2373 | * console registration path, and should invoke cond_resched() | |
2374 | * between lines if allowable. Not doing so can cause a very long | |
2375 | * scheduling stall on a slow console leading to RCU stall and | |
2376 | * softlockup warnings which exacerbate the issue with more | |
2377 | * messages practically incapacitating the system. | |
257ab443 PM |
2378 | * |
2379 | * console_trylock() is not able to detect the preemptive | |
2380 | * context reliably. Therefore the value must be stored before | |
2381 | * and cleared after the the "again" goto label. | |
8d91f8b1 TH |
2382 | */ |
2383 | do_cond_resched = console_may_schedule; | |
257ab443 | 2384 | again: |
78944e54 AD |
2385 | console_may_schedule = 0; |
2386 | ||
a8199371 SS |
2387 | /* |
2388 | * We released the console_sem lock, so we need to recheck if | |
2389 | * cpu is online and (if not) is there at least one CON_ANYTIME | |
2390 | * console. | |
2391 | */ | |
2392 | if (!can_use_console()) { | |
2393 | console_locked = 0; | |
2394 | up_console_sem(); | |
2395 | return; | |
2396 | } | |
2397 | ||
7ff9554b | 2398 | for (;;) { |
62e32ac3 | 2399 | struct printk_log *msg; |
6fe29354 | 2400 | size_t ext_len = 0; |
3ce9a7c0 | 2401 | size_t len; |
7ff9554b | 2402 | |
f975237b SS |
2403 | printk_safe_enter_irqsave(flags); |
2404 | raw_spin_lock(&logbuf_lock); | |
7ff9554b | 2405 | if (console_seq < log_first_seq) { |
51a72ab7 HZ |
2406 | len = sprintf(text, |
2407 | "** %llu printk messages dropped **\n", | |
2408 | log_first_seq - console_seq); | |
84b5ec8a | 2409 | |
7ff9554b KS |
2410 | /* messages are gone, move to first one */ |
2411 | console_seq = log_first_seq; | |
2412 | console_idx = log_first_idx; | |
84b5ec8a WD |
2413 | } else { |
2414 | len = 0; | |
7ff9554b | 2415 | } |
084681d1 | 2416 | skip: |
7ff9554b KS |
2417 | if (console_seq == log_next_seq) |
2418 | break; | |
2419 | ||
2420 | msg = log_from_idx(console_idx); | |
a6ae928c | 2421 | if (suppress_message_printing(msg->level)) { |
084681d1 | 2422 | /* |
a6ae928c PM |
2423 | * Skip record we have buffered and already printed |
2424 | * directly to the console when we received it, and | |
2425 | * record that has level above the console loglevel. | |
084681d1 KS |
2426 | */ |
2427 | console_idx = log_next(console_idx); | |
2428 | console_seq++; | |
2429 | goto skip; | |
2430 | } | |
649e6ee3 | 2431 | |
f92b070f PM |
2432 | /* Output to all consoles once old messages replayed. */ |
2433 | if (unlikely(exclusive_console && | |
2434 | console_seq >= exclusive_console_stop_seq)) { | |
2435 | exclusive_console = NULL; | |
2436 | } | |
2437 | ||
cca10d58 SS |
2438 | len += msg_print_text(msg, |
2439 | console_msg_format & MSG_FORMAT_SYSLOG, | |
e80c1a9d | 2440 | printk_time, text + len, sizeof(text) - len); |
6fe29354 TH |
2441 | if (nr_ext_console_drivers) { |
2442 | ext_len = msg_print_ext_header(ext_text, | |
2443 | sizeof(ext_text), | |
5aa068ea | 2444 | msg, console_seq); |
6fe29354 TH |
2445 | ext_len += msg_print_ext_body(ext_text + ext_len, |
2446 | sizeof(ext_text) - ext_len, | |
2447 | log_dict(msg), msg->dict_len, | |
2448 | log_text(msg), msg->text_len); | |
2449 | } | |
7ff9554b KS |
2450 | console_idx = log_next(console_idx); |
2451 | console_seq++; | |
07354eb1 | 2452 | raw_spin_unlock(&logbuf_lock); |
7ff9554b | 2453 | |
dbdda842 SRV |
2454 | /* |
2455 | * While actively printing out messages, if another printk() | |
2456 | * were to occur on another CPU, it may wait for this one to | |
2457 | * finish. This task can not be preempted if there is a | |
2458 | * waiter waiting to take over. | |
2459 | */ | |
c162d5b4 | 2460 | console_lock_spinning_enable(); |
dbdda842 | 2461 | |
81d68a96 | 2462 | stop_critical_timings(); /* don't trace print latency */ |
d9c23523 | 2463 | call_console_drivers(ext_text, ext_len, text, len); |
81d68a96 | 2464 | start_critical_timings(); |
dbdda842 | 2465 | |
c162d5b4 PM |
2466 | if (console_lock_spinning_disable_and_check()) { |
2467 | printk_safe_exit_irqrestore(flags); | |
43a17111 | 2468 | return; |
c162d5b4 | 2469 | } |
dbdda842 | 2470 | |
f975237b | 2471 | printk_safe_exit_irqrestore(flags); |
8d91f8b1 TH |
2472 | |
2473 | if (do_cond_resched) | |
2474 | cond_resched(); | |
1da177e4 | 2475 | } |
dbdda842 | 2476 | |
1da177e4 | 2477 | console_locked = 0; |
fe3d8ad3 | 2478 | |
07354eb1 | 2479 | raw_spin_unlock(&logbuf_lock); |
4f2a8d3c | 2480 | |
bd8d7cf5 | 2481 | up_console_sem(); |
4f2a8d3c PZ |
2482 | |
2483 | /* | |
2484 | * Someone could have filled up the buffer again, so re-check if there's | |
2485 | * something to flush. In case we cannot trylock the console_sem again, | |
2486 | * there's a new owner and the console_unlock() from them will do the | |
2487 | * flush, no worries. | |
2488 | */ | |
07354eb1 | 2489 | raw_spin_lock(&logbuf_lock); |
7ff9554b | 2490 | retry = console_seq != log_next_seq; |
f975237b SS |
2491 | raw_spin_unlock(&logbuf_lock); |
2492 | printk_safe_exit_irqrestore(flags); | |
09dc3cf9 | 2493 | |
4f2a8d3c PZ |
2494 | if (retry && console_trylock()) |
2495 | goto again; | |
1da177e4 | 2496 | } |
ac751efa | 2497 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 2498 | |
ddad86c2 MW |
2499 | /** |
2500 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
2501 | * |
2502 | * If the console code is currently allowed to sleep, and | |
2503 | * if this CPU should yield the CPU to another task, do | |
2504 | * so here. | |
2505 | * | |
ac751efa | 2506 | * Must be called within console_lock();. |
1da177e4 LT |
2507 | */ |
2508 | void __sched console_conditional_schedule(void) | |
2509 | { | |
2510 | if (console_may_schedule) | |
2511 | cond_resched(); | |
2512 | } | |
2513 | EXPORT_SYMBOL(console_conditional_schedule); | |
2514 | ||
1da177e4 LT |
2515 | void console_unblank(void) |
2516 | { | |
2517 | struct console *c; | |
2518 | ||
2519 | /* | |
2520 | * console_unblank can no longer be called in interrupt context unless | |
2521 | * oops_in_progress is set to 1.. | |
2522 | */ | |
2523 | if (oops_in_progress) { | |
bd8d7cf5 | 2524 | if (down_trylock_console_sem() != 0) |
1da177e4 LT |
2525 | return; |
2526 | } else | |
ac751efa | 2527 | console_lock(); |
1da177e4 LT |
2528 | |
2529 | console_locked = 1; | |
2530 | console_may_schedule = 0; | |
4d091611 | 2531 | for_each_console(c) |
1da177e4 LT |
2532 | if ((c->flags & CON_ENABLED) && c->unblank) |
2533 | c->unblank(); | |
ac751efa | 2534 | console_unlock(); |
1da177e4 | 2535 | } |
1da177e4 | 2536 | |
8d91f8b1 TH |
2537 | /** |
2538 | * console_flush_on_panic - flush console content on panic | |
de6da1e8 | 2539 | * @mode: flush all messages in buffer or just the pending ones |
8d91f8b1 TH |
2540 | * |
2541 | * Immediately output all pending messages no matter what. | |
2542 | */ | |
de6da1e8 | 2543 | void console_flush_on_panic(enum con_flush_mode mode) |
8d91f8b1 TH |
2544 | { |
2545 | /* | |
2546 | * If someone else is holding the console lock, trylock will fail | |
2547 | * and may_schedule may be set. Ignore and proceed to unlock so | |
2548 | * that messages are flushed out. As this can be called from any | |
2549 | * context and we don't want to get preempted while flushing, | |
2550 | * ensure may_schedule is cleared. | |
2551 | */ | |
2552 | console_trylock(); | |
2553 | console_may_schedule = 0; | |
de6da1e8 FT |
2554 | |
2555 | if (mode == CONSOLE_REPLAY_ALL) { | |
2556 | unsigned long flags; | |
2557 | ||
2558 | logbuf_lock_irqsave(flags); | |
2559 | console_seq = log_first_seq; | |
2560 | console_idx = log_first_idx; | |
2561 | logbuf_unlock_irqrestore(flags); | |
2562 | } | |
8d91f8b1 TH |
2563 | console_unlock(); |
2564 | } | |
2565 | ||
1da177e4 LT |
2566 | /* |
2567 | * Return the console tty driver structure and its associated index | |
2568 | */ | |
2569 | struct tty_driver *console_device(int *index) | |
2570 | { | |
2571 | struct console *c; | |
2572 | struct tty_driver *driver = NULL; | |
2573 | ||
ac751efa | 2574 | console_lock(); |
4d091611 | 2575 | for_each_console(c) { |
1da177e4 LT |
2576 | if (!c->device) |
2577 | continue; | |
2578 | driver = c->device(c, index); | |
2579 | if (driver) | |
2580 | break; | |
2581 | } | |
ac751efa | 2582 | console_unlock(); |
1da177e4 LT |
2583 | return driver; |
2584 | } | |
2585 | ||
2586 | /* | |
2587 | * Prevent further output on the passed console device so that (for example) | |
2588 | * serial drivers can disable console output before suspending a port, and can | |
2589 | * re-enable output afterwards. | |
2590 | */ | |
2591 | void console_stop(struct console *console) | |
2592 | { | |
ac751efa | 2593 | console_lock(); |
1da177e4 | 2594 | console->flags &= ~CON_ENABLED; |
ac751efa | 2595 | console_unlock(); |
1da177e4 LT |
2596 | } |
2597 | EXPORT_SYMBOL(console_stop); | |
2598 | ||
2599 | void console_start(struct console *console) | |
2600 | { | |
ac751efa | 2601 | console_lock(); |
1da177e4 | 2602 | console->flags |= CON_ENABLED; |
ac751efa | 2603 | console_unlock(); |
1da177e4 LT |
2604 | } |
2605 | EXPORT_SYMBOL(console_start); | |
2606 | ||
7bf69395 FDN |
2607 | static int __read_mostly keep_bootcon; |
2608 | ||
2609 | static int __init keep_bootcon_setup(char *str) | |
2610 | { | |
2611 | keep_bootcon = 1; | |
27083bac | 2612 | pr_info("debug: skip boot console de-registration.\n"); |
7bf69395 FDN |
2613 | |
2614 | return 0; | |
2615 | } | |
2616 | ||
2617 | early_param("keep_bootcon", keep_bootcon_setup); | |
2618 | ||
1da177e4 LT |
2619 | /* |
2620 | * The console driver calls this routine during kernel initialization | |
2621 | * to register the console printing procedure with printk() and to | |
2622 | * print any messages that were printed by the kernel before the | |
2623 | * console driver was initialized. | |
4d091611 RG |
2624 | * |
2625 | * This can happen pretty early during the boot process (because of | |
2626 | * early_printk) - sometimes before setup_arch() completes - be careful | |
2627 | * of what kernel features are used - they may not be initialised yet. | |
2628 | * | |
2629 | * There are two types of consoles - bootconsoles (early_printk) and | |
2630 | * "real" consoles (everything which is not a bootconsole) which are | |
2631 | * handled differently. | |
2632 | * - Any number of bootconsoles can be registered at any time. | |
2633 | * - As soon as a "real" console is registered, all bootconsoles | |
2634 | * will be unregistered automatically. | |
2635 | * - Once a "real" console is registered, any attempt to register a | |
2636 | * bootconsoles will be rejected | |
1da177e4 | 2637 | */ |
4d091611 | 2638 | void register_console(struct console *newcon) |
1da177e4 | 2639 | { |
40dc5651 | 2640 | int i; |
1da177e4 | 2641 | unsigned long flags; |
4d091611 | 2642 | struct console *bcon = NULL; |
23475408 | 2643 | struct console_cmdline *c; |
b077bafa | 2644 | static bool has_preferred; |
1da177e4 | 2645 | |
16cf48a6 AB |
2646 | if (console_drivers) |
2647 | for_each_console(bcon) | |
2648 | if (WARN(bcon == newcon, | |
2649 | "console '%s%d' already registered\n", | |
2650 | bcon->name, bcon->index)) | |
2651 | return; | |
2652 | ||
4d091611 RG |
2653 | /* |
2654 | * before we register a new CON_BOOT console, make sure we don't | |
2655 | * already have a valid console | |
2656 | */ | |
2657 | if (console_drivers && newcon->flags & CON_BOOT) { | |
2658 | /* find the last or real console */ | |
2659 | for_each_console(bcon) { | |
2660 | if (!(bcon->flags & CON_BOOT)) { | |
27083bac | 2661 | pr_info("Too late to register bootconsole %s%d\n", |
4d091611 RG |
2662 | newcon->name, newcon->index); |
2663 | return; | |
2664 | } | |
2665 | } | |
69331af7 GH |
2666 | } |
2667 | ||
4d091611 RG |
2668 | if (console_drivers && console_drivers->flags & CON_BOOT) |
2669 | bcon = console_drivers; | |
2670 | ||
b077bafa | 2671 | if (!has_preferred || bcon || !console_drivers) |
ad86ee2b | 2672 | has_preferred = preferred_console >= 0; |
1da177e4 LT |
2673 | |
2674 | /* | |
2675 | * See if we want to use this console driver. If we | |
2676 | * didn't select a console we take the first one | |
2677 | * that registers here. | |
2678 | */ | |
b077bafa | 2679 | if (!has_preferred) { |
4d091611 RG |
2680 | if (newcon->index < 0) |
2681 | newcon->index = 0; | |
2682 | if (newcon->setup == NULL || | |
2683 | newcon->setup(newcon, NULL) == 0) { | |
2684 | newcon->flags |= CON_ENABLED; | |
2685 | if (newcon->device) { | |
2686 | newcon->flags |= CON_CONSDEV; | |
b077bafa | 2687 | has_preferred = true; |
cd3a1b85 | 2688 | } |
1da177e4 LT |
2689 | } |
2690 | } | |
2691 | ||
2692 | /* | |
dac8bbba PM |
2693 | * See if this console matches one we selected on |
2694 | * the command line. | |
1da177e4 | 2695 | */ |
dac8bbba PM |
2696 | for (i = 0, c = console_cmdline; |
2697 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2698 | i++, c++) { | |
c7cef0a8 PH |
2699 | if (!newcon->match || |
2700 | newcon->match(newcon, c->name, c->index, c->options) != 0) { | |
2701 | /* default matching */ | |
2702 | BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name)); | |
2703 | if (strcmp(c->name, newcon->name) != 0) | |
2704 | continue; | |
2705 | if (newcon->index >= 0 && | |
2706 | newcon->index != c->index) | |
2707 | continue; | |
2708 | if (newcon->index < 0) | |
2709 | newcon->index = c->index; | |
bbeddf52 | 2710 | |
c7cef0a8 PH |
2711 | if (_braille_register_console(newcon, c)) |
2712 | return; | |
2713 | ||
2714 | if (newcon->setup && | |
2715 | newcon->setup(newcon, c->options) != 0) | |
2716 | break; | |
2717 | } | |
bbeddf52 | 2718 | |
4d091611 | 2719 | newcon->flags |= CON_ENABLED; |
ad86ee2b | 2720 | if (i == preferred_console) { |
4d091611 | 2721 | newcon->flags |= CON_CONSDEV; |
b077bafa | 2722 | has_preferred = true; |
ab4af03a | 2723 | } |
1da177e4 LT |
2724 | break; |
2725 | } | |
2726 | ||
4d091611 | 2727 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
2728 | return; |
2729 | ||
8259cf43 RG |
2730 | /* |
2731 | * If we have a bootconsole, and are switching to a real console, | |
2732 | * don't print everything out again, since when the boot console, and | |
2733 | * the real console are the same physical device, it's annoying to | |
2734 | * see the beginning boot messages twice | |
2735 | */ | |
2736 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 2737 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
2738 | |
2739 | /* | |
2740 | * Put this console in the list - keep the | |
2741 | * preferred driver at the head of the list. | |
2742 | */ | |
ac751efa | 2743 | console_lock(); |
4d091611 RG |
2744 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
2745 | newcon->next = console_drivers; | |
2746 | console_drivers = newcon; | |
2747 | if (newcon->next) | |
2748 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 2749 | } else { |
4d091611 RG |
2750 | newcon->next = console_drivers->next; |
2751 | console_drivers->next = newcon; | |
1da177e4 | 2752 | } |
6fe29354 TH |
2753 | |
2754 | if (newcon->flags & CON_EXTENDED) | |
9627808d | 2755 | nr_ext_console_drivers++; |
6fe29354 | 2756 | |
4d091611 | 2757 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 | 2758 | /* |
ac751efa | 2759 | * console_unlock(); will print out the buffered messages |
1da177e4 LT |
2760 | * for us. |
2761 | */ | |
de6fcbdb | 2762 | logbuf_lock_irqsave(flags); |
7ff9554b KS |
2763 | console_seq = syslog_seq; |
2764 | console_idx = syslog_idx; | |
fe3d8ad3 FT |
2765 | /* |
2766 | * We're about to replay the log buffer. Only do this to the | |
2767 | * just-registered console to avoid excessive message spam to | |
2768 | * the already-registered consoles. | |
884e370e SS |
2769 | * |
2770 | * Set exclusive_console with disabled interrupts to reduce | |
2771 | * race window with eventual console_flush_on_panic() that | |
2772 | * ignores console_lock. | |
fe3d8ad3 FT |
2773 | */ |
2774 | exclusive_console = newcon; | |
f92b070f | 2775 | exclusive_console_stop_seq = console_seq; |
884e370e | 2776 | logbuf_unlock_irqrestore(flags); |
1da177e4 | 2777 | } |
ac751efa | 2778 | console_unlock(); |
fbc92a34 | 2779 | console_sysfs_notify(); |
8259cf43 RG |
2780 | |
2781 | /* | |
2782 | * By unregistering the bootconsoles after we enable the real console | |
2783 | * we get the "console xxx enabled" message on all the consoles - | |
2784 | * boot consoles, real consoles, etc - this is to ensure that end | |
2785 | * users know there might be something in the kernel's log buffer that | |
2786 | * went to the bootconsole (that they do not see on the real console) | |
2787 | */ | |
27083bac | 2788 | pr_info("%sconsole [%s%d] enabled\n", |
6b802394 KC |
2789 | (newcon->flags & CON_BOOT) ? "boot" : "" , |
2790 | newcon->name, newcon->index); | |
7bf69395 FDN |
2791 | if (bcon && |
2792 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && | |
2793 | !keep_bootcon) { | |
6b802394 KC |
2794 | /* We need to iterate through all boot consoles, to make |
2795 | * sure we print everything out, before we unregister them. | |
8259cf43 | 2796 | */ |
8259cf43 RG |
2797 | for_each_console(bcon) |
2798 | if (bcon->flags & CON_BOOT) | |
2799 | unregister_console(bcon); | |
8259cf43 | 2800 | } |
1da177e4 LT |
2801 | } |
2802 | EXPORT_SYMBOL(register_console); | |
2803 | ||
40dc5651 | 2804 | int unregister_console(struct console *console) |
1da177e4 | 2805 | { |
40dc5651 | 2806 | struct console *a, *b; |
bbeddf52 | 2807 | int res; |
1da177e4 | 2808 | |
27083bac | 2809 | pr_info("%sconsole [%s%d] disabled\n", |
6b802394 KC |
2810 | (console->flags & CON_BOOT) ? "boot" : "" , |
2811 | console->name, console->index); | |
2812 | ||
bbeddf52 JP |
2813 | res = _braille_unregister_console(console); |
2814 | if (res) | |
2815 | return res; | |
f7511d5f | 2816 | |
bbeddf52 | 2817 | res = 1; |
ac751efa | 2818 | console_lock(); |
1da177e4 LT |
2819 | if (console_drivers == console) { |
2820 | console_drivers=console->next; | |
2821 | res = 0; | |
e9b15b54 | 2822 | } else if (console_drivers) { |
1da177e4 LT |
2823 | for (a=console_drivers->next, b=console_drivers ; |
2824 | a; b=a, a=b->next) { | |
2825 | if (a == console) { | |
2826 | b->next = a->next; | |
2827 | res = 0; | |
2828 | break; | |
40dc5651 | 2829 | } |
1da177e4 LT |
2830 | } |
2831 | } | |
40dc5651 | 2832 | |
6fe29354 TH |
2833 | if (!res && (console->flags & CON_EXTENDED)) |
2834 | nr_ext_console_drivers--; | |
2835 | ||
69331af7 | 2836 | /* |
ab4af03a GE |
2837 | * If this isn't the last console and it has CON_CONSDEV set, we |
2838 | * need to set it on the next preferred console. | |
1da177e4 | 2839 | */ |
69331af7 | 2840 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 2841 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 | 2842 | |
7fa21dd8 | 2843 | console->flags &= ~CON_ENABLED; |
ac751efa | 2844 | console_unlock(); |
fbc92a34 | 2845 | console_sysfs_notify(); |
1da177e4 LT |
2846 | return res; |
2847 | } | |
2848 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 2849 | |
0c688614 NP |
2850 | /* |
2851 | * Initialize the console device. This is called *early*, so | |
2852 | * we can't necessarily depend on lots of kernel help here. | |
2853 | * Just do some early initializations, and do the complex setup | |
2854 | * later. | |
2855 | */ | |
2856 | void __init console_init(void) | |
2857 | { | |
58eacfff | 2858 | int ret; |
1b1eeca7 AB |
2859 | initcall_t call; |
2860 | initcall_entry_t *ce; | |
0c688614 NP |
2861 | |
2862 | /* Setup the default TTY line discipline. */ | |
2863 | n_tty_init(); | |
2864 | ||
2865 | /* | |
2866 | * set up the console device so that later boot sequences can | |
2867 | * inform about problems etc.. | |
2868 | */ | |
1b1eeca7 | 2869 | ce = __con_initcall_start; |
58eacfff | 2870 | trace_initcall_level("console"); |
1b1eeca7 AB |
2871 | while (ce < __con_initcall_end) { |
2872 | call = initcall_from_entry(ce); | |
2873 | trace_initcall_start(call); | |
2874 | ret = call(); | |
2875 | trace_initcall_finish(call, ret); | |
2876 | ce++; | |
0c688614 NP |
2877 | } |
2878 | } | |
2879 | ||
81cc26f2 TR |
2880 | /* |
2881 | * Some boot consoles access data that is in the init section and which will | |
2882 | * be discarded after the initcalls have been run. To make sure that no code | |
2883 | * will access this data, unregister the boot consoles in a late initcall. | |
2884 | * | |
2885 | * If for some reason, such as deferred probe or the driver being a loadable | |
2886 | * module, the real console hasn't registered yet at this point, there will | |
2887 | * be a brief interval in which no messages are logged to the console, which | |
2888 | * makes it difficult to diagnose problems that occur during this time. | |
2889 | * | |
2890 | * To mitigate this problem somewhat, only unregister consoles whose memory | |
2b1be689 MR |
2891 | * intersects with the init section. Note that all other boot consoles will |
2892 | * get unregistred when the real preferred console is registered. | |
81cc26f2 | 2893 | */ |
034260d6 | 2894 | static int __init printk_late_init(void) |
0c5564bd | 2895 | { |
4d091611 | 2896 | struct console *con; |
90b14889 | 2897 | int ret; |
4d091611 RG |
2898 | |
2899 | for_each_console(con) { | |
5a814231 PM |
2900 | if (!(con->flags & CON_BOOT)) |
2901 | continue; | |
2902 | ||
2903 | /* Check addresses that might be used for enabled consoles. */ | |
2904 | if (init_section_intersects(con, sizeof(*con)) || | |
2905 | init_section_contains(con->write, 0) || | |
2906 | init_section_contains(con->read, 0) || | |
2907 | init_section_contains(con->device, 0) || | |
2908 | init_section_contains(con->unblank, 0) || | |
2909 | init_section_contains(con->data, 0)) { | |
81cc26f2 | 2910 | /* |
2b1be689 MR |
2911 | * Please, consider moving the reported consoles out |
2912 | * of the init section. | |
81cc26f2 | 2913 | */ |
2b1be689 MR |
2914 | pr_warn("bootconsole [%s%d] uses init memory and must be disabled even before the real one is ready\n", |
2915 | con->name, con->index); | |
2916 | unregister_console(con); | |
cb00e99c | 2917 | } |
0c5564bd | 2918 | } |
90b14889 SAS |
2919 | ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL, |
2920 | console_cpu_notify); | |
2921 | WARN_ON(ret < 0); | |
2922 | ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "printk:online", | |
2923 | console_cpu_notify, NULL); | |
2924 | WARN_ON(ret < 0); | |
0c5564bd RG |
2925 | return 0; |
2926 | } | |
034260d6 | 2927 | late_initcall(printk_late_init); |
0c5564bd | 2928 | |
7ef3d2fd | 2929 | #if defined CONFIG_PRINTK |
dc72c32e FW |
2930 | /* |
2931 | * Delayed printk version, for scheduler-internal messages: | |
2932 | */ | |
dc72c32e | 2933 | #define PRINTK_PENDING_WAKEUP 0x01 |
458df9fd | 2934 | #define PRINTK_PENDING_OUTPUT 0x02 |
dc72c32e FW |
2935 | |
2936 | static DEFINE_PER_CPU(int, printk_pending); | |
dc72c32e FW |
2937 | |
2938 | static void wake_up_klogd_work_func(struct irq_work *irq_work) | |
2939 | { | |
2940 | int pending = __this_cpu_xchg(printk_pending, 0); | |
2941 | ||
458df9fd SR |
2942 | if (pending & PRINTK_PENDING_OUTPUT) { |
2943 | /* If trylock fails, someone else is doing the printing */ | |
2944 | if (console_trylock()) | |
2945 | console_unlock(); | |
dc72c32e FW |
2946 | } |
2947 | ||
2948 | if (pending & PRINTK_PENDING_WAKEUP) | |
2949 | wake_up_interruptible(&log_wait); | |
2950 | } | |
2951 | ||
2952 | static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { | |
2953 | .func = wake_up_klogd_work_func, | |
2954 | .flags = IRQ_WORK_LAZY, | |
2955 | }; | |
2956 | ||
2957 | void wake_up_klogd(void) | |
2958 | { | |
2959 | preempt_disable(); | |
2960 | if (waitqueue_active(&log_wait)) { | |
2961 | this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); | |
bb964a92 | 2962 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
dc72c32e FW |
2963 | } |
2964 | preempt_enable(); | |
2965 | } | |
717115e1 | 2966 | |
a338f84d | 2967 | void defer_console_output(void) |
600e1458 | 2968 | { |
719f6a70 | 2969 | preempt_disable(); |
458df9fd | 2970 | __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); |
bb964a92 | 2971 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
81954606 | 2972 | preempt_enable(); |
a338f84d PM |
2973 | } |
2974 | ||
2975 | int vprintk_deferred(const char *fmt, va_list args) | |
2976 | { | |
2977 | int r; | |
2978 | ||
2979 | r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args); | |
2980 | defer_console_output(); | |
600e1458 PZ |
2981 | |
2982 | return r; | |
2983 | } | |
2984 | ||
719f6a70 PM |
2985 | int printk_deferred(const char *fmt, ...) |
2986 | { | |
2987 | va_list args; | |
2988 | int r; | |
2989 | ||
2990 | va_start(args, fmt); | |
2991 | r = vprintk_deferred(fmt, args); | |
2992 | va_end(args); | |
2993 | ||
2994 | return r; | |
2995 | } | |
2996 | ||
1da177e4 LT |
2997 | /* |
2998 | * printk rate limiting, lifted from the networking subsystem. | |
2999 | * | |
641de9d8 UKK |
3000 | * This enforces a rate limit: not more than 10 kernel messages |
3001 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 3002 | */ |
641de9d8 UKK |
3003 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
3004 | ||
5c828713 | 3005 | int __printk_ratelimit(const char *func) |
1da177e4 | 3006 | { |
5c828713 | 3007 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 3008 | } |
5c828713 | 3009 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
3010 | |
3011 | /** | |
3012 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
3013 | * @caller_jiffies: pointer to caller's state | |
3014 | * @interval_msecs: minimum interval between prints | |
3015 | * | |
3016 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
3017 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
3018 | * returned true. | |
3019 | */ | |
3020 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
3021 | unsigned int interval_msecs) | |
3022 | { | |
249771b8 AE |
3023 | unsigned long elapsed = jiffies - *caller_jiffies; |
3024 | ||
3025 | if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) | |
3026 | return false; | |
3027 | ||
3028 | *caller_jiffies = jiffies; | |
3029 | return true; | |
f46c4833 AM |
3030 | } |
3031 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
3032 | |
3033 | static DEFINE_SPINLOCK(dump_list_lock); | |
3034 | static LIST_HEAD(dump_list); | |
3035 | ||
3036 | /** | |
3037 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 3038 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
3039 | * |
3040 | * Adds a kernel log dumper to the system. The dump callback in the | |
3041 | * structure will be called when the kernel oopses or panics and must be | |
3042 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
3043 | */ | |
3044 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
3045 | { | |
3046 | unsigned long flags; | |
3047 | int err = -EBUSY; | |
3048 | ||
3049 | /* The dump callback needs to be set */ | |
3050 | if (!dumper->dump) | |
3051 | return -EINVAL; | |
3052 | ||
3053 | spin_lock_irqsave(&dump_list_lock, flags); | |
3054 | /* Don't allow registering multiple times */ | |
3055 | if (!dumper->registered) { | |
3056 | dumper->registered = 1; | |
fb842b00 | 3057 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
3058 | err = 0; |
3059 | } | |
3060 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
3061 | ||
3062 | return err; | |
3063 | } | |
3064 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
3065 | ||
3066 | /** | |
3067 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 3068 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
3069 | * |
3070 | * Removes a dump device from the system. Returns zero on success and | |
3071 | * %-EINVAL otherwise. | |
3072 | */ | |
3073 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
3074 | { | |
3075 | unsigned long flags; | |
3076 | int err = -EINVAL; | |
3077 | ||
3078 | spin_lock_irqsave(&dump_list_lock, flags); | |
3079 | if (dumper->registered) { | |
3080 | dumper->registered = 0; | |
fb842b00 | 3081 | list_del_rcu(&dumper->list); |
456b565c SK |
3082 | err = 0; |
3083 | } | |
3084 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 3085 | synchronize_rcu(); |
456b565c SK |
3086 | |
3087 | return err; | |
3088 | } | |
3089 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
3090 | ||
7ff9554b KS |
3091 | static bool always_kmsg_dump; |
3092 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); | |
3093 | ||
456b565c SK |
3094 | /** |
3095 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
3096 | * @reason: the reason (oops, panic etc) for dumping | |
3097 | * | |
e2ae715d KS |
3098 | * Call each of the registered dumper's dump() callback, which can |
3099 | * retrieve the kmsg records with kmsg_dump_get_line() or | |
3100 | * kmsg_dump_get_buffer(). | |
456b565c SK |
3101 | */ |
3102 | void kmsg_dump(enum kmsg_dump_reason reason) | |
3103 | { | |
456b565c | 3104 | struct kmsg_dumper *dumper; |
456b565c SK |
3105 | unsigned long flags; |
3106 | ||
c22ab332 MG |
3107 | if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump) |
3108 | return; | |
3109 | ||
e2ae715d KS |
3110 | rcu_read_lock(); |
3111 | list_for_each_entry_rcu(dumper, &dump_list, list) { | |
3112 | if (dumper->max_reason && reason > dumper->max_reason) | |
3113 | continue; | |
3114 | ||
3115 | /* initialize iterator with data about the stored records */ | |
3116 | dumper->active = true; | |
3117 | ||
de6fcbdb | 3118 | logbuf_lock_irqsave(flags); |
e2ae715d KS |
3119 | dumper->cur_seq = clear_seq; |
3120 | dumper->cur_idx = clear_idx; | |
3121 | dumper->next_seq = log_next_seq; | |
3122 | dumper->next_idx = log_next_idx; | |
de6fcbdb | 3123 | logbuf_unlock_irqrestore(flags); |
e2ae715d KS |
3124 | |
3125 | /* invoke dumper which will iterate over records */ | |
3126 | dumper->dump(dumper, reason); | |
3127 | ||
3128 | /* reset iterator */ | |
3129 | dumper->active = false; | |
3130 | } | |
3131 | rcu_read_unlock(); | |
3132 | } | |
3133 | ||
3134 | /** | |
533827c9 | 3135 | * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version) |
e2ae715d KS |
3136 | * @dumper: registered kmsg dumper |
3137 | * @syslog: include the "<4>" prefixes | |
3138 | * @line: buffer to copy the line to | |
3139 | * @size: maximum size of the buffer | |
3140 | * @len: length of line placed into buffer | |
3141 | * | |
3142 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
3143 | * record, and copy one record into the provided buffer. | |
3144 | * | |
3145 | * Consecutive calls will return the next available record moving | |
3146 | * towards the end of the buffer with the youngest messages. | |
3147 | * | |
3148 | * A return value of FALSE indicates that there are no more records to | |
3149 | * read. | |
533827c9 AV |
3150 | * |
3151 | * The function is similar to kmsg_dump_get_line(), but grabs no locks. | |
e2ae715d | 3152 | */ |
533827c9 AV |
3153 | bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog, |
3154 | char *line, size_t size, size_t *len) | |
e2ae715d | 3155 | { |
62e32ac3 | 3156 | struct printk_log *msg; |
e2ae715d KS |
3157 | size_t l = 0; |
3158 | bool ret = false; | |
3159 | ||
3160 | if (!dumper->active) | |
3161 | goto out; | |
7ff9554b | 3162 | |
e2ae715d KS |
3163 | if (dumper->cur_seq < log_first_seq) { |
3164 | /* messages are gone, move to first available one */ | |
3165 | dumper->cur_seq = log_first_seq; | |
3166 | dumper->cur_idx = log_first_idx; | |
3167 | } | |
456b565c | 3168 | |
e2ae715d | 3169 | /* last entry */ |
533827c9 | 3170 | if (dumper->cur_seq >= log_next_seq) |
e2ae715d | 3171 | goto out; |
456b565c | 3172 | |
e2ae715d | 3173 | msg = log_from_idx(dumper->cur_idx); |
e80c1a9d | 3174 | l = msg_print_text(msg, syslog, printk_time, line, size); |
e2ae715d KS |
3175 | |
3176 | dumper->cur_idx = log_next(dumper->cur_idx); | |
3177 | dumper->cur_seq++; | |
3178 | ret = true; | |
e2ae715d KS |
3179 | out: |
3180 | if (len) | |
3181 | *len = l; | |
3182 | return ret; | |
3183 | } | |
533827c9 AV |
3184 | |
3185 | /** | |
3186 | * kmsg_dump_get_line - retrieve one kmsg log line | |
3187 | * @dumper: registered kmsg dumper | |
3188 | * @syslog: include the "<4>" prefixes | |
3189 | * @line: buffer to copy the line to | |
3190 | * @size: maximum size of the buffer | |
3191 | * @len: length of line placed into buffer | |
3192 | * | |
3193 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
3194 | * record, and copy one record into the provided buffer. | |
3195 | * | |
3196 | * Consecutive calls will return the next available record moving | |
3197 | * towards the end of the buffer with the youngest messages. | |
3198 | * | |
3199 | * A return value of FALSE indicates that there are no more records to | |
3200 | * read. | |
3201 | */ | |
3202 | bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, | |
3203 | char *line, size_t size, size_t *len) | |
3204 | { | |
3205 | unsigned long flags; | |
3206 | bool ret; | |
3207 | ||
de6fcbdb | 3208 | logbuf_lock_irqsave(flags); |
533827c9 | 3209 | ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len); |
de6fcbdb | 3210 | logbuf_unlock_irqrestore(flags); |
533827c9 AV |
3211 | |
3212 | return ret; | |
3213 | } | |
e2ae715d KS |
3214 | EXPORT_SYMBOL_GPL(kmsg_dump_get_line); |
3215 | ||
3216 | /** | |
3217 | * kmsg_dump_get_buffer - copy kmsg log lines | |
3218 | * @dumper: registered kmsg dumper | |
3219 | * @syslog: include the "<4>" prefixes | |
4f0f4af5 | 3220 | * @buf: buffer to copy the line to |
e2ae715d KS |
3221 | * @size: maximum size of the buffer |
3222 | * @len: length of line placed into buffer | |
3223 | * | |
3224 | * Start at the end of the kmsg buffer and fill the provided buffer | |
3225 | * with as many of the the *youngest* kmsg records that fit into it. | |
3226 | * If the buffer is large enough, all available kmsg records will be | |
3227 | * copied with a single call. | |
3228 | * | |
3229 | * Consecutive calls will fill the buffer with the next block of | |
3230 | * available older records, not including the earlier retrieved ones. | |
3231 | * | |
3232 | * A return value of FALSE indicates that there are no more records to | |
3233 | * read. | |
3234 | */ | |
3235 | bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, | |
3236 | char *buf, size_t size, size_t *len) | |
3237 | { | |
3238 | unsigned long flags; | |
3239 | u64 seq; | |
3240 | u32 idx; | |
3241 | u64 next_seq; | |
3242 | u32 next_idx; | |
3243 | size_t l = 0; | |
3244 | bool ret = false; | |
e80c1a9d | 3245 | bool time = printk_time; |
e2ae715d KS |
3246 | |
3247 | if (!dumper->active) | |
3248 | goto out; | |
3249 | ||
de6fcbdb | 3250 | logbuf_lock_irqsave(flags); |
e2ae715d KS |
3251 | if (dumper->cur_seq < log_first_seq) { |
3252 | /* messages are gone, move to first available one */ | |
3253 | dumper->cur_seq = log_first_seq; | |
3254 | dumper->cur_idx = log_first_idx; | |
3255 | } | |
3256 | ||
3257 | /* last entry */ | |
3258 | if (dumper->cur_seq >= dumper->next_seq) { | |
de6fcbdb | 3259 | logbuf_unlock_irqrestore(flags); |
e2ae715d KS |
3260 | goto out; |
3261 | } | |
3262 | ||
3263 | /* calculate length of entire buffer */ | |
3264 | seq = dumper->cur_seq; | |
3265 | idx = dumper->cur_idx; | |
3266 | while (seq < dumper->next_seq) { | |
62e32ac3 | 3267 | struct printk_log *msg = log_from_idx(idx); |
e2ae715d | 3268 | |
e80c1a9d | 3269 | l += msg_print_text(msg, true, time, NULL, 0); |
e2ae715d KS |
3270 | idx = log_next(idx); |
3271 | seq++; | |
3272 | } | |
3273 | ||
3274 | /* move first record forward until length fits into the buffer */ | |
3275 | seq = dumper->cur_seq; | |
3276 | idx = dumper->cur_idx; | |
3277 | while (l > size && seq < dumper->next_seq) { | |
62e32ac3 | 3278 | struct printk_log *msg = log_from_idx(idx); |
456b565c | 3279 | |
e80c1a9d | 3280 | l -= msg_print_text(msg, true, time, NULL, 0); |
e2ae715d KS |
3281 | idx = log_next(idx); |
3282 | seq++; | |
456b565c | 3283 | } |
e2ae715d KS |
3284 | |
3285 | /* last message in next interation */ | |
3286 | next_seq = seq; | |
3287 | next_idx = idx; | |
3288 | ||
3289 | l = 0; | |
3290 | while (seq < dumper->next_seq) { | |
62e32ac3 | 3291 | struct printk_log *msg = log_from_idx(idx); |
e2ae715d | 3292 | |
e80c1a9d | 3293 | l += msg_print_text(msg, syslog, time, buf + l, size - l); |
e2ae715d KS |
3294 | idx = log_next(idx); |
3295 | seq++; | |
3296 | } | |
3297 | ||
3298 | dumper->next_seq = next_seq; | |
3299 | dumper->next_idx = next_idx; | |
3300 | ret = true; | |
de6fcbdb | 3301 | logbuf_unlock_irqrestore(flags); |
e2ae715d KS |
3302 | out: |
3303 | if (len) | |
3304 | *len = l; | |
3305 | return ret; | |
3306 | } | |
3307 | EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); | |
456b565c | 3308 | |
533827c9 AV |
3309 | /** |
3310 | * kmsg_dump_rewind_nolock - reset the interator (unlocked version) | |
3311 | * @dumper: registered kmsg dumper | |
3312 | * | |
3313 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
3314 | * kmsg_dump_get_buffer() can be called again and used multiple | |
3315 | * times within the same dumper.dump() callback. | |
3316 | * | |
3317 | * The function is similar to kmsg_dump_rewind(), but grabs no locks. | |
3318 | */ | |
3319 | void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper) | |
3320 | { | |
3321 | dumper->cur_seq = clear_seq; | |
3322 | dumper->cur_idx = clear_idx; | |
3323 | dumper->next_seq = log_next_seq; | |
3324 | dumper->next_idx = log_next_idx; | |
3325 | } | |
3326 | ||
e2ae715d KS |
3327 | /** |
3328 | * kmsg_dump_rewind - reset the interator | |
3329 | * @dumper: registered kmsg dumper | |
3330 | * | |
3331 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
3332 | * kmsg_dump_get_buffer() can be called again and used multiple | |
3333 | * times within the same dumper.dump() callback. | |
3334 | */ | |
3335 | void kmsg_dump_rewind(struct kmsg_dumper *dumper) | |
3336 | { | |
3337 | unsigned long flags; | |
3338 | ||
de6fcbdb | 3339 | logbuf_lock_irqsave(flags); |
533827c9 | 3340 | kmsg_dump_rewind_nolock(dumper); |
de6fcbdb | 3341 | logbuf_unlock_irqrestore(flags); |
456b565c | 3342 | } |
e2ae715d | 3343 | EXPORT_SYMBOL_GPL(kmsg_dump_rewind); |
196779b9 | 3344 | |
7ef3d2fd | 3345 | #endif |