Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/kernel/printk.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * Modified to make sys_syslog() more flexible: added commands to | |
7 | * return the last 4k of kernel messages, regardless of whether | |
8 | * they've been read or not. Added option to suppress kernel printk's | |
9 | * to the console. Added hook for sending the console messages | |
10 | * elsewhere, in preparation for a serial line console (someday). | |
11 | * Ted Ts'o, 2/11/93. | |
12 | * Modified for sysctl support, 1/8/97, Chris Horn. | |
40dc5651 | 13 | * Fixed SMP synchronization, 08/08/99, Manfred Spraul |
624dffcb | 14 | * manfred@colorfullife.com |
1da177e4 | 15 | * Rewrote bits to get rid of console_lock |
e1f8e874 | 16 | * 01Mar01 Andrew Morton |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/tty.h> | |
22 | #include <linux/tty_driver.h> | |
1da177e4 LT |
23 | #include <linux/console.h> |
24 | #include <linux/init.h> | |
bfe8df3d RD |
25 | #include <linux/jiffies.h> |
26 | #include <linux/nmi.h> | |
1da177e4 | 27 | #include <linux/module.h> |
3b9c0410 | 28 | #include <linux/moduleparam.h> |
1da177e4 LT |
29 | #include <linux/delay.h> |
30 | #include <linux/smp.h> | |
31 | #include <linux/security.h> | |
32 | #include <linux/bootmem.h> | |
162a7e75 | 33 | #include <linux/memblock.h> |
1da177e4 | 34 | #include <linux/syscalls.h> |
692f66f2 | 35 | #include <linux/crash_core.h> |
d37d39ae | 36 | #include <linux/kdb.h> |
3fff4c42 | 37 | #include <linux/ratelimit.h> |
456b565c | 38 | #include <linux/kmsg_dump.h> |
00234592 | 39 | #include <linux/syslog.h> |
034260d6 | 40 | #include <linux/cpu.h> |
fb842b00 | 41 | #include <linux/rculist.h> |
e11fea92 | 42 | #include <linux/poll.h> |
74876a98 | 43 | #include <linux/irq_work.h> |
249771b8 | 44 | #include <linux/ctype.h> |
e2e40f2c | 45 | #include <linux/uio.h> |
e6017571 | 46 | #include <linux/sched/clock.h> |
b17b0153 | 47 | #include <linux/sched/debug.h> |
68db0cf1 | 48 | #include <linux/sched/task_stack.h> |
1da177e4 | 49 | |
7c0f6ba6 | 50 | #include <linux/uaccess.h> |
40a7d9f5 | 51 | #include <asm/sections.h> |
1da177e4 | 52 | |
58eacfff | 53 | #include <trace/events/initcall.h> |
95100358 JB |
54 | #define CREATE_TRACE_POINTS |
55 | #include <trace/events/printk.h> | |
56 | ||
d197c43d | 57 | #include "console_cmdline.h" |
bbeddf52 | 58 | #include "braille.h" |
42a0bb3f | 59 | #include "internal.h" |
d197c43d | 60 | |
1da177e4 | 61 | int console_printk[4] = { |
a8fe19eb | 62 | CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */ |
42a9dc0b | 63 | MESSAGE_LOGLEVEL_DEFAULT, /* default_message_loglevel */ |
a8fe19eb BP |
64 | CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */ |
65 | CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ | |
1da177e4 LT |
66 | }; |
67 | ||
56e6c104 TZ |
68 | atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0); |
69 | EXPORT_SYMBOL(ignore_console_lock_warning); | |
70 | ||
1da177e4 | 71 | /* |
0bbfb7c2 | 72 | * Low level drivers may need that to know if they can schedule in |
1da177e4 LT |
73 | * their unblank() callback or not. So let's export it. |
74 | */ | |
75 | int oops_in_progress; | |
76 | EXPORT_SYMBOL(oops_in_progress); | |
77 | ||
78 | /* | |
79 | * console_sem protects the console_drivers list, and also | |
80 | * provides serialisation for access to the entire console | |
81 | * driver system. | |
82 | */ | |
5b8c4f23 | 83 | static DEFINE_SEMAPHORE(console_sem); |
1da177e4 | 84 | struct console *console_drivers; |
a29d1cfe IM |
85 | EXPORT_SYMBOL_GPL(console_drivers); |
86 | ||
daee7797 DV |
87 | #ifdef CONFIG_LOCKDEP |
88 | static struct lockdep_map console_lock_dep_map = { | |
89 | .name = "console_lock" | |
90 | }; | |
91 | #endif | |
92 | ||
750afe7b BP |
93 | enum devkmsg_log_bits { |
94 | __DEVKMSG_LOG_BIT_ON = 0, | |
95 | __DEVKMSG_LOG_BIT_OFF, | |
96 | __DEVKMSG_LOG_BIT_LOCK, | |
97 | }; | |
98 | ||
99 | enum devkmsg_log_masks { | |
100 | DEVKMSG_LOG_MASK_ON = BIT(__DEVKMSG_LOG_BIT_ON), | |
101 | DEVKMSG_LOG_MASK_OFF = BIT(__DEVKMSG_LOG_BIT_OFF), | |
102 | DEVKMSG_LOG_MASK_LOCK = BIT(__DEVKMSG_LOG_BIT_LOCK), | |
103 | }; | |
104 | ||
105 | /* Keep both the 'on' and 'off' bits clear, i.e. ratelimit by default: */ | |
106 | #define DEVKMSG_LOG_MASK_DEFAULT 0 | |
107 | ||
108 | static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; | |
109 | ||
110 | static int __control_devkmsg(char *str) | |
111 | { | |
112 | if (!str) | |
113 | return -EINVAL; | |
114 | ||
115 | if (!strncmp(str, "on", 2)) { | |
116 | devkmsg_log = DEVKMSG_LOG_MASK_ON; | |
117 | return 2; | |
118 | } else if (!strncmp(str, "off", 3)) { | |
119 | devkmsg_log = DEVKMSG_LOG_MASK_OFF; | |
120 | return 3; | |
121 | } else if (!strncmp(str, "ratelimit", 9)) { | |
122 | devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; | |
123 | return 9; | |
124 | } | |
125 | return -EINVAL; | |
126 | } | |
127 | ||
128 | static int __init control_devkmsg(char *str) | |
129 | { | |
130 | if (__control_devkmsg(str) < 0) | |
131 | return 1; | |
132 | ||
133 | /* | |
134 | * Set sysctl string accordingly: | |
135 | */ | |
6fd78a1a SS |
136 | if (devkmsg_log == DEVKMSG_LOG_MASK_ON) |
137 | strcpy(devkmsg_log_str, "on"); | |
138 | else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF) | |
139 | strcpy(devkmsg_log_str, "off"); | |
750afe7b BP |
140 | /* else "ratelimit" which is set by default. */ |
141 | ||
142 | /* | |
143 | * Sysctl cannot change it anymore. The kernel command line setting of | |
144 | * this parameter is to force the setting to be permanent throughout the | |
145 | * runtime of the system. This is a precation measure against userspace | |
146 | * trying to be a smarta** and attempting to change it up on us. | |
147 | */ | |
148 | devkmsg_log |= DEVKMSG_LOG_MASK_LOCK; | |
149 | ||
150 | return 0; | |
151 | } | |
152 | __setup("printk.devkmsg=", control_devkmsg); | |
153 | ||
154 | char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit"; | |
155 | ||
156 | int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, | |
157 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
158 | { | |
159 | char old_str[DEVKMSG_STR_MAX_SIZE]; | |
160 | unsigned int old; | |
161 | int err; | |
162 | ||
163 | if (write) { | |
164 | if (devkmsg_log & DEVKMSG_LOG_MASK_LOCK) | |
165 | return -EINVAL; | |
166 | ||
167 | old = devkmsg_log; | |
168 | strncpy(old_str, devkmsg_log_str, DEVKMSG_STR_MAX_SIZE); | |
169 | } | |
170 | ||
171 | err = proc_dostring(table, write, buffer, lenp, ppos); | |
172 | if (err) | |
173 | return err; | |
174 | ||
175 | if (write) { | |
176 | err = __control_devkmsg(devkmsg_log_str); | |
177 | ||
178 | /* | |
179 | * Do not accept an unknown string OR a known string with | |
180 | * trailing crap... | |
181 | */ | |
182 | if (err < 0 || (err + 1 != *lenp)) { | |
183 | ||
184 | /* ... and restore old setting. */ | |
185 | devkmsg_log = old; | |
186 | strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE); | |
187 | ||
188 | return -EINVAL; | |
189 | } | |
190 | } | |
191 | ||
192 | return 0; | |
193 | } | |
194 | ||
6fe29354 TH |
195 | /* |
196 | * Number of registered extended console drivers. | |
197 | * | |
198 | * If extended consoles are present, in-kernel cont reassembly is disabled | |
199 | * and each fragment is stored as a separate log entry with proper | |
200 | * continuation flag so that every emitted message has full metadata. This | |
201 | * doesn't change the result for regular consoles or /proc/kmsg. For | |
202 | * /dev/kmsg, as long as the reader concatenates messages according to | |
203 | * consecutive continuation flags, the end result should be the same too. | |
204 | */ | |
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 KS |
354 | LOG_NEWLINE = 2, /* text ended with a newline */ |
355 | LOG_PREFIX = 4, /* text started with a prefix */ | |
356 | LOG_CONT = 8, /* text is a fragment of a continuation line */ | |
084681d1 KS |
357 | }; |
358 | ||
62e32ac3 | 359 | struct printk_log { |
7ff9554b KS |
360 | u64 ts_nsec; /* timestamp in nanoseconds */ |
361 | u16 len; /* length of entire record */ | |
362 | u16 text_len; /* length of text buffer */ | |
363 | u16 dict_len; /* length of dictionary buffer */ | |
084681d1 KS |
364 | u8 facility; /* syslog facility */ |
365 | u8 flags:5; /* internal record flags */ | |
366 | u8 level:3; /* syslog level */ | |
5c9cf8af AR |
367 | } |
368 | #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS | |
369 | __packed __aligned(4) | |
370 | #endif | |
371 | ; | |
7ff9554b KS |
372 | |
373 | /* | |
458df9fd SR |
374 | * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken |
375 | * within the scheduler's rq lock. It must be released before calling | |
376 | * console_unlock() or anything else that might wake up a process. | |
7ff9554b | 377 | */ |
cf9b1106 | 378 | DEFINE_RAW_SPINLOCK(logbuf_lock); |
d59745ce | 379 | |
de6fcbdb SS |
380 | /* |
381 | * Helper macros to lock/unlock logbuf_lock and switch between | |
382 | * printk-safe/unsafe modes. | |
383 | */ | |
384 | #define logbuf_lock_irq() \ | |
385 | do { \ | |
386 | printk_safe_enter_irq(); \ | |
387 | raw_spin_lock(&logbuf_lock); \ | |
388 | } while (0) | |
389 | ||
390 | #define logbuf_unlock_irq() \ | |
391 | do { \ | |
392 | raw_spin_unlock(&logbuf_lock); \ | |
393 | printk_safe_exit_irq(); \ | |
394 | } while (0) | |
395 | ||
396 | #define logbuf_lock_irqsave(flags) \ | |
397 | do { \ | |
398 | printk_safe_enter_irqsave(flags); \ | |
399 | raw_spin_lock(&logbuf_lock); \ | |
400 | } while (0) | |
401 | ||
402 | #define logbuf_unlock_irqrestore(flags) \ | |
403 | do { \ | |
404 | raw_spin_unlock(&logbuf_lock); \ | |
405 | printk_safe_exit_irqrestore(flags); \ | |
406 | } while (0) | |
407 | ||
96efedf1 | 408 | #ifdef CONFIG_PRINTK |
dc72c32e | 409 | DECLARE_WAIT_QUEUE_HEAD(log_wait); |
7f3a781d KS |
410 | /* the next printk record to read by syslog(READ) or /proc/kmsg */ |
411 | static u64 syslog_seq; | |
412 | static u32 syslog_idx; | |
eb02dac9 | 413 | static size_t syslog_partial; |
7ff9554b KS |
414 | |
415 | /* index and sequence number of the first record stored in the buffer */ | |
416 | static u64 log_first_seq; | |
417 | static u32 log_first_idx; | |
418 | ||
419 | /* index and sequence number of the next record to store in the buffer */ | |
420 | static u64 log_next_seq; | |
421 | static u32 log_next_idx; | |
422 | ||
eab07260 KS |
423 | /* the next printk record to write to the console */ |
424 | static u64 console_seq; | |
425 | static u32 console_idx; | |
eab07260 | 426 | |
7ff9554b KS |
427 | /* the next printk record to read after the last 'clear' command */ |
428 | static u64 clear_seq; | |
429 | static u32 clear_idx; | |
430 | ||
70498253 | 431 | #define PREFIX_MAX 32 |
249771b8 | 432 | #define LOG_LINE_MAX (1024 - PREFIX_MAX) |
7f3a781d | 433 | |
3824657c MK |
434 | #define LOG_LEVEL(v) ((v) & 0x07) |
435 | #define LOG_FACILITY(v) ((v) >> 3 & 0xff) | |
436 | ||
7f3a781d | 437 | /* record buffer */ |
62e32ac3 | 438 | #define LOG_ALIGN __alignof__(struct printk_log) |
7f3a781d | 439 | #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
f8450fca | 440 | static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); |
7f3a781d KS |
441 | static char *log_buf = __log_buf; |
442 | static u32 log_buf_len = __LOG_BUF_LEN; | |
443 | ||
14c4000a VH |
444 | /* Return log buffer address */ |
445 | char *log_buf_addr_get(void) | |
446 | { | |
447 | return log_buf; | |
448 | } | |
449 | ||
450 | /* Return log buffer size */ | |
451 | u32 log_buf_len_get(void) | |
452 | { | |
453 | return log_buf_len; | |
454 | } | |
455 | ||
7ff9554b | 456 | /* human readable text of the record */ |
62e32ac3 | 457 | static char *log_text(const struct printk_log *msg) |
7ff9554b | 458 | { |
62e32ac3 | 459 | return (char *)msg + sizeof(struct printk_log); |
7ff9554b KS |
460 | } |
461 | ||
462 | /* optional key/value pair dictionary attached to the record */ | |
62e32ac3 | 463 | static char *log_dict(const struct printk_log *msg) |
7ff9554b | 464 | { |
62e32ac3 | 465 | return (char *)msg + sizeof(struct printk_log) + msg->text_len; |
7ff9554b KS |
466 | } |
467 | ||
468 | /* get record by index; idx must point to valid msg */ | |
62e32ac3 | 469 | static struct printk_log *log_from_idx(u32 idx) |
7ff9554b | 470 | { |
62e32ac3 | 471 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); |
7ff9554b KS |
472 | |
473 | /* | |
474 | * A length == 0 record is the end of buffer marker. Wrap around and | |
475 | * read the message at the start of the buffer. | |
476 | */ | |
477 | if (!msg->len) | |
62e32ac3 | 478 | return (struct printk_log *)log_buf; |
7ff9554b KS |
479 | return msg; |
480 | } | |
481 | ||
482 | /* get next record; idx must point to valid msg */ | |
483 | static u32 log_next(u32 idx) | |
484 | { | |
62e32ac3 | 485 | struct printk_log *msg = (struct printk_log *)(log_buf + idx); |
7ff9554b KS |
486 | |
487 | /* length == 0 indicates the end of the buffer; wrap */ | |
488 | /* | |
489 | * A length == 0 record is the end of buffer marker. Wrap around and | |
490 | * read the message at the start of the buffer as *this* one, and | |
491 | * return the one after that. | |
492 | */ | |
493 | if (!msg->len) { | |
62e32ac3 | 494 | msg = (struct printk_log *)log_buf; |
7ff9554b KS |
495 | return msg->len; |
496 | } | |
497 | return idx + msg->len; | |
498 | } | |
499 | ||
f40e4b9f PM |
500 | /* |
501 | * Check whether there is enough free space for the given message. | |
502 | * | |
503 | * The same values of first_idx and next_idx mean that the buffer | |
504 | * is either empty or full. | |
505 | * | |
506 | * If the buffer is empty, we must respect the position of the indexes. | |
507 | * They cannot be reset to the beginning of the buffer. | |
508 | */ | |
509 | static int logbuf_has_space(u32 msg_size, bool empty) | |
0a581694 PM |
510 | { |
511 | u32 free; | |
512 | ||
f40e4b9f | 513 | if (log_next_idx > log_first_idx || empty) |
0a581694 PM |
514 | free = max(log_buf_len - log_next_idx, log_first_idx); |
515 | else | |
516 | free = log_first_idx - log_next_idx; | |
517 | ||
518 | /* | |
519 | * We need space also for an empty header that signalizes wrapping | |
520 | * of the buffer. | |
521 | */ | |
522 | return free >= msg_size + sizeof(struct printk_log); | |
523 | } | |
524 | ||
f40e4b9f | 525 | static int log_make_free_space(u32 msg_size) |
0a581694 | 526 | { |
f468908b ID |
527 | while (log_first_seq < log_next_seq && |
528 | !logbuf_has_space(msg_size, false)) { | |
0b90fec3 | 529 | /* drop old messages until we have enough contiguous space */ |
0a581694 PM |
530 | log_first_idx = log_next(log_first_idx); |
531 | log_first_seq++; | |
532 | } | |
f40e4b9f | 533 | |
f468908b ID |
534 | if (clear_seq < log_first_seq) { |
535 | clear_seq = log_first_seq; | |
536 | clear_idx = log_first_idx; | |
537 | } | |
538 | ||
f40e4b9f | 539 | /* sequence numbers are equal, so the log buffer is empty */ |
f468908b | 540 | if (logbuf_has_space(msg_size, log_first_seq == log_next_seq)) |
f40e4b9f PM |
541 | return 0; |
542 | ||
543 | return -ENOMEM; | |
0a581694 PM |
544 | } |
545 | ||
85c87043 PM |
546 | /* compute the message size including the padding bytes */ |
547 | static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len) | |
548 | { | |
549 | u32 size; | |
550 | ||
551 | size = sizeof(struct printk_log) + text_len + dict_len; | |
552 | *pad_len = (-size) & (LOG_ALIGN - 1); | |
553 | size += *pad_len; | |
554 | ||
555 | return size; | |
556 | } | |
557 | ||
55bd53a4 PM |
558 | /* |
559 | * Define how much of the log buffer we could take at maximum. The value | |
560 | * must be greater than two. Note that only half of the buffer is available | |
561 | * when the index points to the middle. | |
562 | */ | |
563 | #define MAX_LOG_TAKE_PART 4 | |
564 | static const char trunc_msg[] = "<truncated>"; | |
565 | ||
566 | static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len, | |
567 | u16 *dict_len, u32 *pad_len) | |
568 | { | |
569 | /* | |
570 | * The message should not take the whole buffer. Otherwise, it might | |
571 | * get removed too soon. | |
572 | */ | |
573 | u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART; | |
574 | if (*text_len > max_text_len) | |
575 | *text_len = max_text_len; | |
576 | /* enable the warning message */ | |
577 | *trunc_msg_len = strlen(trunc_msg); | |
578 | /* disable the "dict" completely */ | |
579 | *dict_len = 0; | |
580 | /* compute the size again, count also the warning message */ | |
581 | return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len); | |
582 | } | |
583 | ||
7ff9554b | 584 | /* insert record into the buffer, discard old ones, update heads */ |
034633cc PM |
585 | static int log_store(int facility, int level, |
586 | enum log_flags flags, u64 ts_nsec, | |
587 | const char *dict, u16 dict_len, | |
588 | const char *text, u16 text_len) | |
7ff9554b | 589 | { |
62e32ac3 | 590 | struct printk_log *msg; |
7ff9554b | 591 | u32 size, pad_len; |
55bd53a4 | 592 | u16 trunc_msg_len = 0; |
7ff9554b KS |
593 | |
594 | /* number of '\0' padding bytes to next message */ | |
85c87043 | 595 | size = msg_used_size(text_len, dict_len, &pad_len); |
7ff9554b | 596 | |
55bd53a4 PM |
597 | if (log_make_free_space(size)) { |
598 | /* truncate the message if it is too long for empty buffer */ | |
599 | size = truncate_msg(&text_len, &trunc_msg_len, | |
600 | &dict_len, &pad_len); | |
601 | /* survive when the log buffer is too small for trunc_msg */ | |
602 | if (log_make_free_space(size)) | |
034633cc | 603 | return 0; |
55bd53a4 | 604 | } |
7ff9554b | 605 | |
39b25109 | 606 | if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) { |
7ff9554b KS |
607 | /* |
608 | * This message + an additional empty header does not fit | |
609 | * at the end of the buffer. Add an empty header with len == 0 | |
610 | * to signify a wrap around. | |
611 | */ | |
62e32ac3 | 612 | memset(log_buf + log_next_idx, 0, sizeof(struct printk_log)); |
7ff9554b KS |
613 | log_next_idx = 0; |
614 | } | |
615 | ||
616 | /* fill message */ | |
62e32ac3 | 617 | msg = (struct printk_log *)(log_buf + log_next_idx); |
7ff9554b KS |
618 | memcpy(log_text(msg), text, text_len); |
619 | msg->text_len = text_len; | |
55bd53a4 PM |
620 | if (trunc_msg_len) { |
621 | memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len); | |
622 | msg->text_len += trunc_msg_len; | |
623 | } | |
7ff9554b KS |
624 | memcpy(log_dict(msg), dict, dict_len); |
625 | msg->dict_len = dict_len; | |
084681d1 KS |
626 | msg->facility = facility; |
627 | msg->level = level & 7; | |
628 | msg->flags = flags & 0x1f; | |
629 | if (ts_nsec > 0) | |
630 | msg->ts_nsec = ts_nsec; | |
631 | else | |
632 | msg->ts_nsec = local_clock(); | |
7ff9554b | 633 | memset(log_dict(msg) + dict_len, 0, pad_len); |
fce6e033 | 634 | msg->len = size; |
7ff9554b KS |
635 | |
636 | /* insert message */ | |
637 | log_next_idx += msg->len; | |
638 | log_next_seq++; | |
034633cc PM |
639 | |
640 | return msg->text_len; | |
7ff9554b | 641 | } |
d59745ce | 642 | |
e99aa461 | 643 | int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); |
637241a9 KC |
644 | |
645 | static int syslog_action_restricted(int type) | |
646 | { | |
647 | if (dmesg_restrict) | |
648 | return 1; | |
649 | /* | |
650 | * Unless restricted, we allow "read all" and "get buffer size" | |
651 | * for everybody. | |
652 | */ | |
653 | return type != SYSLOG_ACTION_READ_ALL && | |
654 | type != SYSLOG_ACTION_SIZE_BUFFER; | |
655 | } | |
656 | ||
c71b02e4 | 657 | static int check_syslog_permissions(int type, int source) |
637241a9 KC |
658 | { |
659 | /* | |
660 | * If this is from /proc/kmsg and we've already opened it, then we've | |
661 | * already done the capabilities checks at open time. | |
662 | */ | |
3ea4331c | 663 | if (source == SYSLOG_FROM_PROC && type != SYSLOG_ACTION_OPEN) |
d194e5d6 | 664 | goto ok; |
637241a9 KC |
665 | |
666 | if (syslog_action_restricted(type)) { | |
667 | if (capable(CAP_SYSLOG)) | |
d194e5d6 | 668 | goto ok; |
637241a9 KC |
669 | /* |
670 | * For historical reasons, accept CAP_SYS_ADMIN too, with | |
671 | * a warning. | |
672 | */ | |
673 | if (capable(CAP_SYS_ADMIN)) { | |
674 | pr_warn_once("%s (%d): Attempt to access syslog with " | |
675 | "CAP_SYS_ADMIN but no CAP_SYSLOG " | |
676 | "(deprecated).\n", | |
677 | current->comm, task_pid_nr(current)); | |
d194e5d6 | 678 | goto ok; |
637241a9 KC |
679 | } |
680 | return -EPERM; | |
681 | } | |
d194e5d6 | 682 | ok: |
637241a9 KC |
683 | return security_syslog(type); |
684 | } | |
685 | ||
d43ff430 TH |
686 | static void append_char(char **pp, char *e, char c) |
687 | { | |
688 | if (*pp < e) | |
689 | *(*pp)++ = c; | |
690 | } | |
637241a9 | 691 | |
0a295e67 | 692 | static ssize_t msg_print_ext_header(char *buf, size_t size, |
5aa068ea | 693 | struct printk_log *msg, u64 seq) |
0a295e67 TH |
694 | { |
695 | u64 ts_usec = msg->ts_nsec; | |
0a295e67 TH |
696 | |
697 | do_div(ts_usec, 1000); | |
698 | ||
0a295e67 | 699 | return scnprintf(buf, size, "%u,%llu,%llu,%c;", |
5aa068ea LT |
700 | (msg->facility << 3) | msg->level, seq, ts_usec, |
701 | msg->flags & LOG_CONT ? 'c' : '-'); | |
0a295e67 TH |
702 | } |
703 | ||
704 | static ssize_t msg_print_ext_body(char *buf, size_t size, | |
705 | char *dict, size_t dict_len, | |
706 | char *text, size_t text_len) | |
707 | { | |
708 | char *p = buf, *e = buf + size; | |
709 | size_t i; | |
710 | ||
711 | /* escape non-printable characters */ | |
712 | for (i = 0; i < text_len; i++) { | |
713 | unsigned char c = text[i]; | |
714 | ||
715 | if (c < ' ' || c >= 127 || c == '\\') | |
716 | p += scnprintf(p, e - p, "\\x%02x", c); | |
717 | else | |
718 | append_char(&p, e, c); | |
719 | } | |
720 | append_char(&p, e, '\n'); | |
721 | ||
722 | if (dict_len) { | |
723 | bool line = true; | |
724 | ||
725 | for (i = 0; i < dict_len; i++) { | |
726 | unsigned char c = dict[i]; | |
727 | ||
728 | if (line) { | |
729 | append_char(&p, e, ' '); | |
730 | line = false; | |
731 | } | |
732 | ||
733 | if (c == '\0') { | |
734 | append_char(&p, e, '\n'); | |
735 | line = true; | |
736 | continue; | |
737 | } | |
738 | ||
739 | if (c < ' ' || c >= 127 || c == '\\') { | |
740 | p += scnprintf(p, e - p, "\\x%02x", c); | |
741 | continue; | |
742 | } | |
743 | ||
744 | append_char(&p, e, c); | |
745 | } | |
746 | append_char(&p, e, '\n'); | |
747 | } | |
748 | ||
749 | return p - buf; | |
750 | } | |
751 | ||
e11fea92 KS |
752 | /* /dev/kmsg - userspace message inject/listen interface */ |
753 | struct devkmsg_user { | |
754 | u64 seq; | |
755 | u32 idx; | |
750afe7b | 756 | struct ratelimit_state rs; |
e11fea92 | 757 | struct mutex lock; |
d43ff430 | 758 | char buf[CONSOLE_EXT_LOG_MAX]; |
e11fea92 KS |
759 | }; |
760 | ||
849f3127 | 761 | static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from) |
e11fea92 KS |
762 | { |
763 | char *buf, *line; | |
e11fea92 KS |
764 | int level = default_message_loglevel; |
765 | int facility = 1; /* LOG_USER */ | |
750afe7b BP |
766 | struct file *file = iocb->ki_filp; |
767 | struct devkmsg_user *user = file->private_data; | |
66ee59af | 768 | size_t len = iov_iter_count(from); |
e11fea92 KS |
769 | ssize_t ret = len; |
770 | ||
750afe7b | 771 | if (!user || len > LOG_LINE_MAX) |
e11fea92 | 772 | return -EINVAL; |
750afe7b BP |
773 | |
774 | /* Ignore when user logging is disabled. */ | |
775 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) | |
776 | return len; | |
777 | ||
778 | /* Ratelimit when not explicitly enabled. */ | |
779 | if (!(devkmsg_log & DEVKMSG_LOG_MASK_ON)) { | |
780 | if (!___ratelimit(&user->rs, current->comm)) | |
781 | return ret; | |
782 | } | |
783 | ||
e11fea92 KS |
784 | buf = kmalloc(len+1, GFP_KERNEL); |
785 | if (buf == NULL) | |
786 | return -ENOMEM; | |
787 | ||
849f3127 | 788 | buf[len] = '\0'; |
cbbd26b8 | 789 | if (!copy_from_iter_full(buf, len, from)) { |
849f3127 AV |
790 | kfree(buf); |
791 | return -EFAULT; | |
e11fea92 KS |
792 | } |
793 | ||
794 | /* | |
795 | * Extract and skip the syslog prefix <[0-9]*>. Coming from userspace | |
796 | * the decimal value represents 32bit, the lower 3 bit are the log | |
797 | * level, the rest are the log facility. | |
798 | * | |
799 | * If no prefix or no userspace facility is specified, we | |
800 | * enforce LOG_USER, to be able to reliably distinguish | |
801 | * kernel-generated messages from userspace-injected ones. | |
802 | */ | |
803 | line = buf; | |
804 | if (line[0] == '<') { | |
805 | char *endp = NULL; | |
3824657c | 806 | unsigned int u; |
e11fea92 | 807 | |
3824657c | 808 | u = simple_strtoul(line + 1, &endp, 10); |
e11fea92 | 809 | if (endp && endp[0] == '>') { |
3824657c MK |
810 | level = LOG_LEVEL(u); |
811 | if (LOG_FACILITY(u) != 0) | |
812 | facility = LOG_FACILITY(u); | |
e11fea92 KS |
813 | endp++; |
814 | len -= endp - line; | |
815 | line = endp; | |
816 | } | |
817 | } | |
e11fea92 KS |
818 | |
819 | printk_emit(facility, level, NULL, 0, "%s", line); | |
e11fea92 KS |
820 | kfree(buf); |
821 | return ret; | |
822 | } | |
823 | ||
824 | static ssize_t devkmsg_read(struct file *file, char __user *buf, | |
825 | size_t count, loff_t *ppos) | |
826 | { | |
827 | struct devkmsg_user *user = file->private_data; | |
62e32ac3 | 828 | struct printk_log *msg; |
e11fea92 KS |
829 | size_t len; |
830 | ssize_t ret; | |
831 | ||
832 | if (!user) | |
833 | return -EBADF; | |
834 | ||
4a77a5a0 YL |
835 | ret = mutex_lock_interruptible(&user->lock); |
836 | if (ret) | |
837 | return ret; | |
de6fcbdb SS |
838 | |
839 | logbuf_lock_irq(); | |
e11fea92 KS |
840 | while (user->seq == log_next_seq) { |
841 | if (file->f_flags & O_NONBLOCK) { | |
842 | ret = -EAGAIN; | |
de6fcbdb | 843 | logbuf_unlock_irq(); |
e11fea92 KS |
844 | goto out; |
845 | } | |
846 | ||
de6fcbdb | 847 | logbuf_unlock_irq(); |
e11fea92 KS |
848 | ret = wait_event_interruptible(log_wait, |
849 | user->seq != log_next_seq); | |
850 | if (ret) | |
851 | goto out; | |
de6fcbdb | 852 | logbuf_lock_irq(); |
e11fea92 KS |
853 | } |
854 | ||
855 | if (user->seq < log_first_seq) { | |
856 | /* our last seen message is gone, return error and reset */ | |
857 | user->idx = log_first_idx; | |
858 | user->seq = log_first_seq; | |
859 | ret = -EPIPE; | |
de6fcbdb | 860 | logbuf_unlock_irq(); |
e11fea92 KS |
861 | goto out; |
862 | } | |
863 | ||
864 | msg = log_from_idx(user->idx); | |
0a295e67 | 865 | len = msg_print_ext_header(user->buf, sizeof(user->buf), |
5aa068ea | 866 | msg, user->seq); |
0a295e67 TH |
867 | len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len, |
868 | log_dict(msg), msg->dict_len, | |
869 | log_text(msg), msg->text_len); | |
d39f3d77 | 870 | |
e11fea92 KS |
871 | user->idx = log_next(user->idx); |
872 | user->seq++; | |
de6fcbdb | 873 | logbuf_unlock_irq(); |
e11fea92 KS |
874 | |
875 | if (len > count) { | |
876 | ret = -EINVAL; | |
877 | goto out; | |
878 | } | |
879 | ||
880 | if (copy_to_user(buf, user->buf, len)) { | |
881 | ret = -EFAULT; | |
882 | goto out; | |
883 | } | |
884 | ret = len; | |
885 | out: | |
886 | mutex_unlock(&user->lock); | |
887 | return ret; | |
888 | } | |
889 | ||
890 | static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence) | |
891 | { | |
892 | struct devkmsg_user *user = file->private_data; | |
893 | loff_t ret = 0; | |
894 | ||
895 | if (!user) | |
896 | return -EBADF; | |
897 | if (offset) | |
898 | return -ESPIPE; | |
899 | ||
de6fcbdb | 900 | logbuf_lock_irq(); |
e11fea92 KS |
901 | switch (whence) { |
902 | case SEEK_SET: | |
903 | /* the first record */ | |
904 | user->idx = log_first_idx; | |
905 | user->seq = log_first_seq; | |
906 | break; | |
907 | case SEEK_DATA: | |
908 | /* | |
909 | * The first record after the last SYSLOG_ACTION_CLEAR, | |
910 | * like issued by 'dmesg -c'. Reading /dev/kmsg itself | |
911 | * changes no global state, and does not clear anything. | |
912 | */ | |
913 | user->idx = clear_idx; | |
914 | user->seq = clear_seq; | |
915 | break; | |
916 | case SEEK_END: | |
917 | /* after the last record */ | |
918 | user->idx = log_next_idx; | |
919 | user->seq = log_next_seq; | |
920 | break; | |
921 | default: | |
922 | ret = -EINVAL; | |
923 | } | |
de6fcbdb | 924 | logbuf_unlock_irq(); |
e11fea92 KS |
925 | return ret; |
926 | } | |
927 | ||
9dd95748 | 928 | static __poll_t devkmsg_poll(struct file *file, poll_table *wait) |
e11fea92 KS |
929 | { |
930 | struct devkmsg_user *user = file->private_data; | |
9dd95748 | 931 | __poll_t ret = 0; |
e11fea92 KS |
932 | |
933 | if (!user) | |
a9a08845 | 934 | return EPOLLERR|EPOLLNVAL; |
e11fea92 KS |
935 | |
936 | poll_wait(file, &log_wait, wait); | |
937 | ||
de6fcbdb | 938 | logbuf_lock_irq(); |
e11fea92 KS |
939 | if (user->seq < log_next_seq) { |
940 | /* return error when data has vanished underneath us */ | |
941 | if (user->seq < log_first_seq) | |
a9a08845 | 942 | ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI; |
0a285317 | 943 | else |
a9a08845 | 944 | ret = EPOLLIN|EPOLLRDNORM; |
e11fea92 | 945 | } |
de6fcbdb | 946 | logbuf_unlock_irq(); |
e11fea92 KS |
947 | |
948 | return ret; | |
949 | } | |
950 | ||
951 | static int devkmsg_open(struct inode *inode, struct file *file) | |
952 | { | |
953 | struct devkmsg_user *user; | |
954 | int err; | |
955 | ||
750afe7b BP |
956 | if (devkmsg_log & DEVKMSG_LOG_MASK_OFF) |
957 | return -EPERM; | |
e11fea92 | 958 | |
750afe7b BP |
959 | /* write-only does not need any file context */ |
960 | if ((file->f_flags & O_ACCMODE) != O_WRONLY) { | |
961 | err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, | |
962 | SYSLOG_FROM_READER); | |
963 | if (err) | |
964 | return err; | |
965 | } | |
e11fea92 KS |
966 | |
967 | user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL); | |
968 | if (!user) | |
969 | return -ENOMEM; | |
970 | ||
750afe7b BP |
971 | ratelimit_default_init(&user->rs); |
972 | ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE); | |
973 | ||
e11fea92 KS |
974 | mutex_init(&user->lock); |
975 | ||
de6fcbdb | 976 | logbuf_lock_irq(); |
e11fea92 KS |
977 | user->idx = log_first_idx; |
978 | user->seq = log_first_seq; | |
de6fcbdb | 979 | logbuf_unlock_irq(); |
e11fea92 KS |
980 | |
981 | file->private_data = user; | |
982 | return 0; | |
983 | } | |
984 | ||
985 | static int devkmsg_release(struct inode *inode, struct file *file) | |
986 | { | |
987 | struct devkmsg_user *user = file->private_data; | |
988 | ||
989 | if (!user) | |
990 | return 0; | |
991 | ||
750afe7b BP |
992 | ratelimit_state_exit(&user->rs); |
993 | ||
e11fea92 KS |
994 | mutex_destroy(&user->lock); |
995 | kfree(user); | |
996 | return 0; | |
997 | } | |
998 | ||
999 | const struct file_operations kmsg_fops = { | |
1000 | .open = devkmsg_open, | |
1001 | .read = devkmsg_read, | |
849f3127 | 1002 | .write_iter = devkmsg_write, |
e11fea92 KS |
1003 | .llseek = devkmsg_llseek, |
1004 | .poll = devkmsg_poll, | |
1005 | .release = devkmsg_release, | |
1006 | }; | |
1007 | ||
692f66f2 | 1008 | #ifdef CONFIG_CRASH_CORE |
04d491ab | 1009 | /* |
4c1ace64 | 1010 | * This appends the listed symbols to /proc/vmcore |
04d491ab | 1011 | * |
4c1ace64 | 1012 | * /proc/vmcore is used by various utilities, like crash and makedumpfile to |
04d491ab NH |
1013 | * obtain access to symbols that are otherwise very difficult to locate. These |
1014 | * symbols are specifically used so that utilities can access and extract the | |
1015 | * dmesg log from a vmcore file after a crash. | |
1016 | */ | |
692f66f2 | 1017 | void log_buf_vmcoreinfo_setup(void) |
04d491ab NH |
1018 | { |
1019 | VMCOREINFO_SYMBOL(log_buf); | |
04d491ab | 1020 | VMCOREINFO_SYMBOL(log_buf_len); |
7ff9554b | 1021 | VMCOREINFO_SYMBOL(log_first_idx); |
f468908b | 1022 | VMCOREINFO_SYMBOL(clear_idx); |
7ff9554b | 1023 | VMCOREINFO_SYMBOL(log_next_idx); |
6791457a | 1024 | /* |
62e32ac3 | 1025 | * Export struct printk_log size and field offsets. User space tools can |
6791457a VG |
1026 | * parse it and detect any changes to structure down the line. |
1027 | */ | |
62e32ac3 JP |
1028 | VMCOREINFO_STRUCT_SIZE(printk_log); |
1029 | VMCOREINFO_OFFSET(printk_log, ts_nsec); | |
1030 | VMCOREINFO_OFFSET(printk_log, len); | |
1031 | VMCOREINFO_OFFSET(printk_log, text_len); | |
1032 | VMCOREINFO_OFFSET(printk_log, dict_len); | |
04d491ab NH |
1033 | } |
1034 | #endif | |
1035 | ||
162a7e75 MT |
1036 | /* requested log_buf_len from kernel cmdline */ |
1037 | static unsigned long __initdata new_log_buf_len; | |
1038 | ||
c0a318a3 LR |
1039 | /* we practice scaling the ring buffer by powers of 2 */ |
1040 | static void __init log_buf_len_update(unsigned size) | |
1da177e4 | 1041 | { |
1da177e4 LT |
1042 | if (size) |
1043 | size = roundup_pow_of_two(size); | |
162a7e75 MT |
1044 | if (size > log_buf_len) |
1045 | new_log_buf_len = size; | |
c0a318a3 LR |
1046 | } |
1047 | ||
1048 | /* save requested log_buf_len since it's too early to process it */ | |
1049 | static int __init log_buf_len_setup(char *str) | |
1050 | { | |
1051 | unsigned size = memparse(str, &str); | |
1052 | ||
1053 | log_buf_len_update(size); | |
162a7e75 MT |
1054 | |
1055 | return 0; | |
1da177e4 | 1056 | } |
162a7e75 MT |
1057 | early_param("log_buf_len", log_buf_len_setup); |
1058 | ||
2240a31d GU |
1059 | #ifdef CONFIG_SMP |
1060 | #define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT) | |
1061 | ||
23b2899f LR |
1062 | static void __init log_buf_add_cpu(void) |
1063 | { | |
1064 | unsigned int cpu_extra; | |
1065 | ||
1066 | /* | |
1067 | * archs should set up cpu_possible_bits properly with | |
1068 | * set_cpu_possible() after setup_arch() but just in | |
1069 | * case lets ensure this is valid. | |
1070 | */ | |
1071 | if (num_possible_cpus() == 1) | |
1072 | return; | |
1073 | ||
1074 | cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN; | |
1075 | ||
1076 | /* by default this will only continue through for large > 64 CPUs */ | |
1077 | if (cpu_extra <= __LOG_BUF_LEN / 2) | |
1078 | return; | |
1079 | ||
1080 | pr_info("log_buf_len individual max cpu contribution: %d bytes\n", | |
1081 | __LOG_CPU_MAX_BUF_LEN); | |
1082 | pr_info("log_buf_len total cpu_extra contributions: %d bytes\n", | |
1083 | cpu_extra); | |
1084 | pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN); | |
1085 | ||
1086 | log_buf_len_update(cpu_extra + __LOG_BUF_LEN); | |
1087 | } | |
2240a31d GU |
1088 | #else /* !CONFIG_SMP */ |
1089 | static inline void log_buf_add_cpu(void) {} | |
1090 | #endif /* CONFIG_SMP */ | |
23b2899f | 1091 | |
162a7e75 MT |
1092 | void __init setup_log_buf(int early) |
1093 | { | |
1094 | unsigned long flags; | |
162a7e75 MT |
1095 | char *new_log_buf; |
1096 | int free; | |
1097 | ||
23b2899f LR |
1098 | if (log_buf != __log_buf) |
1099 | return; | |
1100 | ||
1101 | if (!early && !new_log_buf_len) | |
1102 | log_buf_add_cpu(); | |
1103 | ||
162a7e75 MT |
1104 | if (!new_log_buf_len) |
1105 | return; | |
1da177e4 | 1106 | |
162a7e75 | 1107 | if (early) { |
9da791df | 1108 | new_log_buf = |
70300177 | 1109 | memblock_virt_alloc(new_log_buf_len, LOG_ALIGN); |
162a7e75 | 1110 | } else { |
70300177 LR |
1111 | new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len, |
1112 | LOG_ALIGN); | |
162a7e75 MT |
1113 | } |
1114 | ||
1115 | if (unlikely(!new_log_buf)) { | |
1116 | pr_err("log_buf_len: %ld bytes not available\n", | |
1117 | new_log_buf_len); | |
1118 | return; | |
1119 | } | |
1120 | ||
de6fcbdb | 1121 | logbuf_lock_irqsave(flags); |
162a7e75 MT |
1122 | log_buf_len = new_log_buf_len; |
1123 | log_buf = new_log_buf; | |
1124 | new_log_buf_len = 0; | |
7ff9554b KS |
1125 | free = __LOG_BUF_LEN - log_next_idx; |
1126 | memcpy(log_buf, __log_buf, __LOG_BUF_LEN); | |
de6fcbdb | 1127 | logbuf_unlock_irqrestore(flags); |
162a7e75 | 1128 | |
f5405172 | 1129 | pr_info("log_buf_len: %d bytes\n", log_buf_len); |
162a7e75 MT |
1130 | pr_info("early log buf free: %d(%d%%)\n", |
1131 | free, (free * 100) / __LOG_BUF_LEN); | |
1132 | } | |
1da177e4 | 1133 | |
2fa72c8f AC |
1134 | static bool __read_mostly ignore_loglevel; |
1135 | ||
1136 | static int __init ignore_loglevel_setup(char *str) | |
1137 | { | |
d25d9fec | 1138 | ignore_loglevel = true; |
27083bac | 1139 | pr_info("debug: ignoring loglevel setting.\n"); |
2fa72c8f AC |
1140 | |
1141 | return 0; | |
1142 | } | |
1143 | ||
1144 | early_param("ignore_loglevel", ignore_loglevel_setup); | |
1145 | module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR); | |
205bd3d2 JP |
1146 | MODULE_PARM_DESC(ignore_loglevel, |
1147 | "ignore loglevel setting (prints all kernel messages to the console)"); | |
2fa72c8f | 1148 | |
cf775444 SS |
1149 | static bool suppress_message_printing(int level) |
1150 | { | |
1151 | return (level >= console_loglevel && !ignore_loglevel); | |
1152 | } | |
1153 | ||
bfe8df3d RD |
1154 | #ifdef CONFIG_BOOT_PRINTK_DELAY |
1155 | ||
674dff65 | 1156 | static int boot_delay; /* msecs delay after each printk during bootup */ |
3a3b6ed2 | 1157 | static unsigned long long loops_per_msec; /* based on boot_delay */ |
bfe8df3d RD |
1158 | |
1159 | static int __init boot_delay_setup(char *str) | |
1160 | { | |
1161 | unsigned long lpj; | |
bfe8df3d RD |
1162 | |
1163 | lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ | |
1164 | loops_per_msec = (unsigned long long)lpj / 1000 * HZ; | |
1165 | ||
1166 | get_option(&str, &boot_delay); | |
1167 | if (boot_delay > 10 * 1000) | |
1168 | boot_delay = 0; | |
1169 | ||
3a3b6ed2 DY |
1170 | pr_debug("boot_delay: %u, preset_lpj: %ld, lpj: %lu, " |
1171 | "HZ: %d, loops_per_msec: %llu\n", | |
1172 | boot_delay, preset_lpj, lpj, HZ, loops_per_msec); | |
29e9d225 | 1173 | return 0; |
bfe8df3d | 1174 | } |
29e9d225 | 1175 | early_param("boot_delay", boot_delay_setup); |
bfe8df3d | 1176 | |
2fa72c8f | 1177 | static void boot_delay_msec(int level) |
bfe8df3d RD |
1178 | { |
1179 | unsigned long long k; | |
1180 | unsigned long timeout; | |
1181 | ||
ff48cd26 | 1182 | if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING) |
cf775444 | 1183 | || suppress_message_printing(level)) { |
bfe8df3d | 1184 | return; |
2fa72c8f | 1185 | } |
bfe8df3d | 1186 | |
3a3b6ed2 | 1187 | k = (unsigned long long)loops_per_msec * boot_delay; |
bfe8df3d RD |
1188 | |
1189 | timeout = jiffies + msecs_to_jiffies(boot_delay); | |
1190 | while (k) { | |
1191 | k--; | |
1192 | cpu_relax(); | |
1193 | /* | |
1194 | * use (volatile) jiffies to prevent | |
1195 | * compiler reduction; loop termination via jiffies | |
1196 | * is secondary and may or may not happen. | |
1197 | */ | |
1198 | if (time_after(jiffies, timeout)) | |
1199 | break; | |
1200 | touch_nmi_watchdog(); | |
1201 | } | |
1202 | } | |
1203 | #else | |
2fa72c8f | 1204 | static inline void boot_delay_msec(int level) |
bfe8df3d RD |
1205 | { |
1206 | } | |
1207 | #endif | |
1208 | ||
e99aa461 | 1209 | static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); |
7ff9554b KS |
1210 | module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); |
1211 | ||
084681d1 KS |
1212 | static size_t print_time(u64 ts, char *buf) |
1213 | { | |
1214 | unsigned long rem_nsec; | |
1215 | ||
1216 | if (!printk_time) | |
1217 | return 0; | |
1218 | ||
35dac27c RD |
1219 | rem_nsec = do_div(ts, 1000000000); |
1220 | ||
084681d1 | 1221 | if (!buf) |
35dac27c | 1222 | return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts); |
084681d1 | 1223 | |
084681d1 KS |
1224 | return sprintf(buf, "[%5lu.%06lu] ", |
1225 | (unsigned long)ts, rem_nsec / 1000); | |
1226 | } | |
1227 | ||
62e32ac3 | 1228 | static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf) |
649e6ee3 | 1229 | { |
3ce9a7c0 | 1230 | size_t len = 0; |
43a73a50 | 1231 | unsigned int prefix = (msg->facility << 3) | msg->level; |
649e6ee3 | 1232 | |
3ce9a7c0 KS |
1233 | if (syslog) { |
1234 | if (buf) { | |
43a73a50 | 1235 | len += sprintf(buf, "<%u>", prefix); |
3ce9a7c0 KS |
1236 | } else { |
1237 | len += 3; | |
43a73a50 KS |
1238 | if (prefix > 999) |
1239 | len += 3; | |
1240 | else if (prefix > 99) | |
1241 | len += 2; | |
1242 | else if (prefix > 9) | |
3ce9a7c0 KS |
1243 | len++; |
1244 | } | |
1245 | } | |
649e6ee3 | 1246 | |
084681d1 | 1247 | len += print_time(msg->ts_nsec, buf ? buf + len : NULL); |
3ce9a7c0 | 1248 | return len; |
649e6ee3 KS |
1249 | } |
1250 | ||
5aa068ea | 1251 | static size_t msg_print_text(const struct printk_log *msg, bool syslog, char *buf, size_t size) |
7ff9554b | 1252 | { |
3ce9a7c0 KS |
1253 | const char *text = log_text(msg); |
1254 | size_t text_size = msg->text_len; | |
1255 | size_t len = 0; | |
1256 | ||
1257 | do { | |
1258 | const char *next = memchr(text, '\n', text_size); | |
1259 | size_t text_len; | |
1260 | ||
1261 | if (next) { | |
1262 | text_len = next - text; | |
1263 | next++; | |
1264 | text_size -= next - text; | |
1265 | } else { | |
1266 | text_len = text_size; | |
1267 | } | |
7ff9554b | 1268 | |
3ce9a7c0 KS |
1269 | if (buf) { |
1270 | if (print_prefix(msg, syslog, NULL) + | |
70498253 | 1271 | text_len + 1 >= size - len) |
3ce9a7c0 | 1272 | break; |
7ff9554b | 1273 | |
5aa068ea | 1274 | len += print_prefix(msg, syslog, buf + len); |
3ce9a7c0 KS |
1275 | memcpy(buf + len, text, text_len); |
1276 | len += text_len; | |
5aa068ea | 1277 | buf[len++] = '\n'; |
3ce9a7c0 KS |
1278 | } else { |
1279 | /* SYSLOG_ACTION_* buffer size only calculation */ | |
5aa068ea | 1280 | len += print_prefix(msg, syslog, NULL); |
5becfb1d | 1281 | len += text_len; |
5aa068ea | 1282 | len++; |
3ce9a7c0 | 1283 | } |
7ff9554b | 1284 | |
3ce9a7c0 KS |
1285 | text = next; |
1286 | } while (text); | |
7ff9554b | 1287 | |
7ff9554b KS |
1288 | return len; |
1289 | } | |
1290 | ||
1291 | static int syslog_print(char __user *buf, int size) | |
1292 | { | |
1293 | char *text; | |
62e32ac3 | 1294 | struct printk_log *msg; |
116e90b2 | 1295 | int len = 0; |
7ff9554b | 1296 | |
70498253 | 1297 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
7ff9554b KS |
1298 | if (!text) |
1299 | return -ENOMEM; | |
1300 | ||
116e90b2 JB |
1301 | while (size > 0) { |
1302 | size_t n; | |
eb02dac9 | 1303 | size_t skip; |
116e90b2 | 1304 | |
de6fcbdb | 1305 | logbuf_lock_irq(); |
116e90b2 JB |
1306 | if (syslog_seq < log_first_seq) { |
1307 | /* messages are gone, move to first one */ | |
1308 | syslog_seq = log_first_seq; | |
1309 | syslog_idx = log_first_idx; | |
eb02dac9 | 1310 | syslog_partial = 0; |
116e90b2 JB |
1311 | } |
1312 | if (syslog_seq == log_next_seq) { | |
de6fcbdb | 1313 | logbuf_unlock_irq(); |
116e90b2 JB |
1314 | break; |
1315 | } | |
eb02dac9 KS |
1316 | |
1317 | skip = syslog_partial; | |
116e90b2 | 1318 | msg = log_from_idx(syslog_idx); |
5aa068ea | 1319 | n = msg_print_text(msg, true, text, LOG_LINE_MAX + PREFIX_MAX); |
eb02dac9 KS |
1320 | if (n - syslog_partial <= size) { |
1321 | /* message fits into buffer, move forward */ | |
116e90b2 JB |
1322 | syslog_idx = log_next(syslog_idx); |
1323 | syslog_seq++; | |
eb02dac9 KS |
1324 | n -= syslog_partial; |
1325 | syslog_partial = 0; | |
1326 | } else if (!len){ | |
1327 | /* partial read(), remember position */ | |
1328 | n = size; | |
1329 | syslog_partial += n; | |
116e90b2 JB |
1330 | } else |
1331 | n = 0; | |
de6fcbdb | 1332 | logbuf_unlock_irq(); |
116e90b2 JB |
1333 | |
1334 | if (!n) | |
1335 | break; | |
1336 | ||
eb02dac9 | 1337 | if (copy_to_user(buf, text + skip, n)) { |
116e90b2 JB |
1338 | if (!len) |
1339 | len = -EFAULT; | |
1340 | break; | |
1341 | } | |
eb02dac9 KS |
1342 | |
1343 | len += n; | |
1344 | size -= n; | |
1345 | buf += n; | |
7ff9554b | 1346 | } |
7ff9554b KS |
1347 | |
1348 | kfree(text); | |
1349 | return len; | |
1350 | } | |
1351 | ||
1352 | static int syslog_print_all(char __user *buf, int size, bool clear) | |
1353 | { | |
1354 | char *text; | |
1355 | int len = 0; | |
63842c21 NG |
1356 | u64 next_seq; |
1357 | u64 seq; | |
1358 | u32 idx; | |
1359 | ||
70498253 | 1360 | text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); |
7ff9554b KS |
1361 | if (!text) |
1362 | return -ENOMEM; | |
1363 | ||
de6fcbdb | 1364 | logbuf_lock_irq(); |
63842c21 NG |
1365 | /* |
1366 | * Find first record that fits, including all following records, | |
1367 | * into the user-provided buffer for this dump. | |
1368 | */ | |
1369 | seq = clear_seq; | |
1370 | idx = clear_idx; | |
1371 | while (seq < log_next_seq) { | |
1372 | struct printk_log *msg = log_from_idx(idx); | |
1373 | ||
1374 | len += msg_print_text(msg, true, NULL, 0); | |
1375 | idx = log_next(idx); | |
1376 | seq++; | |
1377 | } | |
e2ae715d | 1378 | |
63842c21 NG |
1379 | /* move first record forward until length fits into the buffer */ |
1380 | seq = clear_seq; | |
1381 | idx = clear_idx; | |
1382 | while (len > size && seq < log_next_seq) { | |
1383 | struct printk_log *msg = log_from_idx(idx); | |
3ce9a7c0 | 1384 | |
63842c21 NG |
1385 | len -= msg_print_text(msg, true, NULL, 0); |
1386 | idx = log_next(idx); | |
1387 | seq++; | |
1388 | } | |
7ff9554b | 1389 | |
63842c21 NG |
1390 | /* last message fitting into this dump */ |
1391 | next_seq = log_next_seq; | |
7ff9554b | 1392 | |
63842c21 NG |
1393 | len = 0; |
1394 | while (len >= 0 && seq < next_seq) { | |
1395 | struct printk_log *msg = log_from_idx(idx); | |
1396 | int textlen; | |
7ff9554b | 1397 | |
63842c21 NG |
1398 | textlen = msg_print_text(msg, true, text, |
1399 | LOG_LINE_MAX + PREFIX_MAX); | |
1400 | if (textlen < 0) { | |
1401 | len = textlen; | |
1402 | break; | |
1403 | } | |
1404 | idx = log_next(idx); | |
1405 | seq++; | |
7ff9554b | 1406 | |
63842c21 NG |
1407 | logbuf_unlock_irq(); |
1408 | if (copy_to_user(buf + len, text, textlen)) | |
1409 | len = -EFAULT; | |
1410 | else | |
1411 | len += textlen; | |
1412 | logbuf_lock_irq(); | |
7ff9554b | 1413 | |
63842c21 NG |
1414 | if (seq < log_first_seq) { |
1415 | /* messages are gone, move to next one */ | |
1416 | seq = log_first_seq; | |
1417 | idx = log_first_idx; | |
7ff9554b KS |
1418 | } |
1419 | } | |
1420 | ||
1421 | if (clear) { | |
1422 | clear_seq = log_next_seq; | |
1423 | clear_idx = log_next_idx; | |
1424 | } | |
de6fcbdb | 1425 | logbuf_unlock_irq(); |
7ff9554b KS |
1426 | |
1427 | kfree(text); | |
1428 | return len; | |
1429 | } | |
1430 | ||
8599dc7d PM |
1431 | static void syslog_clear(void) |
1432 | { | |
1433 | logbuf_lock_irq(); | |
1434 | clear_seq = log_next_seq; | |
1435 | clear_idx = log_next_idx; | |
1436 | logbuf_unlock_irq(); | |
1437 | } | |
1438 | ||
3ea4331c | 1439 | int do_syslog(int type, char __user *buf, int len, int source) |
1da177e4 | 1440 | { |
7ff9554b | 1441 | bool clear = false; |
a39d4a85 | 1442 | static int saved_console_loglevel = LOGLEVEL_DEFAULT; |
ee24aebf | 1443 | int error; |
1da177e4 | 1444 | |
3ea4331c | 1445 | error = check_syslog_permissions(type, source); |
ee24aebf | 1446 | if (error) |
077a1cc0 | 1447 | return error; |
12b3052c | 1448 | |
1da177e4 | 1449 | switch (type) { |
d78ca3cd | 1450 | case SYSLOG_ACTION_CLOSE: /* Close log */ |
1da177e4 | 1451 | break; |
d78ca3cd | 1452 | case SYSLOG_ACTION_OPEN: /* Open log */ |
1da177e4 | 1453 | break; |
d78ca3cd | 1454 | case SYSLOG_ACTION_READ: /* Read from log */ |
1da177e4 | 1455 | if (!buf || len < 0) |
077a1cc0 | 1456 | return -EINVAL; |
1da177e4 | 1457 | if (!len) |
077a1cc0 NA |
1458 | return 0; |
1459 | if (!access_ok(VERIFY_WRITE, buf, len)) | |
1460 | return -EFAULT; | |
40dc5651 | 1461 | error = wait_event_interruptible(log_wait, |
7ff9554b | 1462 | syslog_seq != log_next_seq); |
cb424ffe | 1463 | if (error) |
077a1cc0 | 1464 | return error; |
7ff9554b | 1465 | error = syslog_print(buf, len); |
1da177e4 | 1466 | break; |
d78ca3cd KC |
1467 | /* Read/clear last kernel messages */ |
1468 | case SYSLOG_ACTION_READ_CLEAR: | |
7ff9554b | 1469 | clear = true; |
1da177e4 | 1470 | /* FALL THRU */ |
d78ca3cd KC |
1471 | /* Read last kernel messages */ |
1472 | case SYSLOG_ACTION_READ_ALL: | |
1da177e4 | 1473 | if (!buf || len < 0) |
077a1cc0 | 1474 | return -EINVAL; |
1da177e4 | 1475 | if (!len) |
077a1cc0 NA |
1476 | return 0; |
1477 | if (!access_ok(VERIFY_WRITE, buf, len)) | |
1478 | return -EFAULT; | |
7ff9554b | 1479 | error = syslog_print_all(buf, len, clear); |
1da177e4 | 1480 | break; |
d78ca3cd KC |
1481 | /* Clear ring buffer */ |
1482 | case SYSLOG_ACTION_CLEAR: | |
8599dc7d | 1483 | syslog_clear(); |
4661e356 | 1484 | break; |
d78ca3cd KC |
1485 | /* Disable logging to console */ |
1486 | case SYSLOG_ACTION_CONSOLE_OFF: | |
a39d4a85 | 1487 | if (saved_console_loglevel == LOGLEVEL_DEFAULT) |
1aaad49e | 1488 | saved_console_loglevel = console_loglevel; |
1da177e4 LT |
1489 | console_loglevel = minimum_console_loglevel; |
1490 | break; | |
d78ca3cd KC |
1491 | /* Enable logging to console */ |
1492 | case SYSLOG_ACTION_CONSOLE_ON: | |
a39d4a85 | 1493 | if (saved_console_loglevel != LOGLEVEL_DEFAULT) { |
1aaad49e | 1494 | console_loglevel = saved_console_loglevel; |
a39d4a85 | 1495 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1aaad49e | 1496 | } |
1da177e4 | 1497 | break; |
d78ca3cd KC |
1498 | /* Set level of messages printed to console */ |
1499 | case SYSLOG_ACTION_CONSOLE_LEVEL: | |
1da177e4 | 1500 | if (len < 1 || len > 8) |
077a1cc0 | 1501 | return -EINVAL; |
1da177e4 LT |
1502 | if (len < minimum_console_loglevel) |
1503 | len = minimum_console_loglevel; | |
1504 | console_loglevel = len; | |
1aaad49e | 1505 | /* Implicitly re-enable logging to console */ |
a39d4a85 | 1506 | saved_console_loglevel = LOGLEVEL_DEFAULT; |
1da177e4 | 1507 | break; |
d78ca3cd KC |
1508 | /* Number of chars in the log buffer */ |
1509 | case SYSLOG_ACTION_SIZE_UNREAD: | |
de6fcbdb | 1510 | logbuf_lock_irq(); |
7ff9554b KS |
1511 | if (syslog_seq < log_first_seq) { |
1512 | /* messages are gone, move to first one */ | |
1513 | syslog_seq = log_first_seq; | |
1514 | syslog_idx = log_first_idx; | |
eb02dac9 | 1515 | syslog_partial = 0; |
7ff9554b | 1516 | } |
3ea4331c | 1517 | if (source == SYSLOG_FROM_PROC) { |
7ff9554b KS |
1518 | /* |
1519 | * Short-cut for poll(/"proc/kmsg") which simply checks | |
1520 | * for pending data, not the size; return the count of | |
1521 | * records, not the length. | |
1522 | */ | |
e97e1267 | 1523 | error = log_next_seq - syslog_seq; |
7ff9554b | 1524 | } else { |
5becfb1d KS |
1525 | u64 seq = syslog_seq; |
1526 | u32 idx = syslog_idx; | |
7ff9554b | 1527 | |
7ff9554b | 1528 | while (seq < log_next_seq) { |
62e32ac3 | 1529 | struct printk_log *msg = log_from_idx(idx); |
3ce9a7c0 | 1530 | |
5aa068ea | 1531 | error += msg_print_text(msg, true, NULL, 0); |
7ff9554b KS |
1532 | idx = log_next(idx); |
1533 | seq++; | |
1534 | } | |
eb02dac9 | 1535 | error -= syslog_partial; |
7ff9554b | 1536 | } |
de6fcbdb | 1537 | logbuf_unlock_irq(); |
1da177e4 | 1538 | break; |
d78ca3cd KC |
1539 | /* Size of the log buffer */ |
1540 | case SYSLOG_ACTION_SIZE_BUFFER: | |
1da177e4 LT |
1541 | error = log_buf_len; |
1542 | break; | |
1543 | default: | |
1544 | error = -EINVAL; | |
1545 | break; | |
1546 | } | |
077a1cc0 | 1547 | |
1da177e4 LT |
1548 | return error; |
1549 | } | |
1550 | ||
1e7bfb21 | 1551 | SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) |
1da177e4 | 1552 | { |
637241a9 | 1553 | return do_syslog(type, buf, len, SYSLOG_FROM_READER); |
1da177e4 LT |
1554 | } |
1555 | ||
c162d5b4 PM |
1556 | /* |
1557 | * Special console_lock variants that help to reduce the risk of soft-lockups. | |
1558 | * They allow to pass console_lock to another printk() call using a busy wait. | |
1559 | */ | |
1560 | ||
1561 | #ifdef CONFIG_LOCKDEP | |
1562 | static struct lockdep_map console_owner_dep_map = { | |
1563 | .name = "console_owner" | |
1564 | }; | |
1565 | #endif | |
1566 | ||
1567 | static DEFINE_RAW_SPINLOCK(console_owner_lock); | |
1568 | static struct task_struct *console_owner; | |
1569 | static bool console_waiter; | |
1570 | ||
1571 | /** | |
1572 | * console_lock_spinning_enable - mark beginning of code where another | |
1573 | * thread might safely busy wait | |
1574 | * | |
1575 | * This basically converts console_lock into a spinlock. This marks | |
1576 | * the section where the console_lock owner can not sleep, because | |
1577 | * there may be a waiter spinning (like a spinlock). Also it must be | |
1578 | * ready to hand over the lock at the end of the section. | |
1579 | */ | |
1580 | static void console_lock_spinning_enable(void) | |
1581 | { | |
1582 | raw_spin_lock(&console_owner_lock); | |
1583 | console_owner = current; | |
1584 | raw_spin_unlock(&console_owner_lock); | |
1585 | ||
1586 | /* The waiter may spin on us after setting console_owner */ | |
1587 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
1588 | } | |
1589 | ||
1590 | /** | |
1591 | * console_lock_spinning_disable_and_check - mark end of code where another | |
1592 | * thread was able to busy wait and check if there is a waiter | |
1593 | * | |
1594 | * This is called at the end of the section where spinning is allowed. | |
1595 | * It has two functions. First, it is a signal that it is no longer | |
1596 | * safe to start busy waiting for the lock. Second, it checks if | |
1597 | * there is a busy waiter and passes the lock rights to her. | |
1598 | * | |
1599 | * Important: Callers lose the lock if there was a busy waiter. | |
1600 | * They must not touch items synchronized by console_lock | |
1601 | * in this case. | |
1602 | * | |
1603 | * Return: 1 if the lock rights were passed, 0 otherwise. | |
1604 | */ | |
1605 | static int console_lock_spinning_disable_and_check(void) | |
1606 | { | |
1607 | int waiter; | |
1608 | ||
1609 | raw_spin_lock(&console_owner_lock); | |
1610 | waiter = READ_ONCE(console_waiter); | |
1611 | console_owner = NULL; | |
1612 | raw_spin_unlock(&console_owner_lock); | |
1613 | ||
1614 | if (!waiter) { | |
1615 | spin_release(&console_owner_dep_map, 1, _THIS_IP_); | |
1616 | return 0; | |
1617 | } | |
1618 | ||
1619 | /* The waiter is now free to continue */ | |
1620 | WRITE_ONCE(console_waiter, false); | |
1621 | ||
1622 | spin_release(&console_owner_dep_map, 1, _THIS_IP_); | |
1623 | ||
1624 | /* | |
1625 | * Hand off console_lock to waiter. The waiter will perform | |
1626 | * the up(). After this, the waiter is the console_lock owner. | |
1627 | */ | |
1628 | mutex_release(&console_lock_dep_map, 1, _THIS_IP_); | |
1629 | return 1; | |
1630 | } | |
1631 | ||
1632 | /** | |
1633 | * console_trylock_spinning - try to get console_lock by busy waiting | |
1634 | * | |
1635 | * This allows to busy wait for the console_lock when the current | |
1636 | * owner is running in specially marked sections. It means that | |
1637 | * the current owner is running and cannot reschedule until it | |
1638 | * is ready to lose the lock. | |
1639 | * | |
1640 | * Return: 1 if we got the lock, 0 othrewise | |
1641 | */ | |
1642 | static int console_trylock_spinning(void) | |
1643 | { | |
1644 | struct task_struct *owner = NULL; | |
1645 | bool waiter; | |
1646 | bool spin = false; | |
1647 | unsigned long flags; | |
1648 | ||
1649 | if (console_trylock()) | |
1650 | return 1; | |
1651 | ||
1652 | printk_safe_enter_irqsave(flags); | |
1653 | ||
1654 | raw_spin_lock(&console_owner_lock); | |
1655 | owner = READ_ONCE(console_owner); | |
1656 | waiter = READ_ONCE(console_waiter); | |
1657 | if (!waiter && owner && owner != current) { | |
1658 | WRITE_ONCE(console_waiter, true); | |
1659 | spin = true; | |
1660 | } | |
1661 | raw_spin_unlock(&console_owner_lock); | |
1662 | ||
1663 | /* | |
1664 | * If there is an active printk() writing to the | |
1665 | * consoles, instead of having it write our data too, | |
1666 | * see if we can offload that load from the active | |
1667 | * printer, and do some printing ourselves. | |
1668 | * Go into a spin only if there isn't already a waiter | |
1669 | * spinning, and there is an active printer, and | |
1670 | * that active printer isn't us (recursive printk?). | |
1671 | */ | |
1672 | if (!spin) { | |
1673 | printk_safe_exit_irqrestore(flags); | |
1674 | return 0; | |
1675 | } | |
1676 | ||
1677 | /* We spin waiting for the owner to release us */ | |
1678 | spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_); | |
1679 | /* Owner will clear console_waiter on hand off */ | |
1680 | while (READ_ONCE(console_waiter)) | |
1681 | cpu_relax(); | |
1682 | spin_release(&console_owner_dep_map, 1, _THIS_IP_); | |
1683 | ||
1684 | printk_safe_exit_irqrestore(flags); | |
1685 | /* | |
1686 | * The owner passed the console lock to us. | |
1687 | * Since we did not spin on console lock, annotate | |
1688 | * this as a trylock. Otherwise lockdep will | |
1689 | * complain. | |
1690 | */ | |
1691 | mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_); | |
1692 | ||
1693 | return 1; | |
1694 | } | |
1695 | ||
1da177e4 LT |
1696 | /* |
1697 | * Call the console drivers, asking them to write out | |
1698 | * log_buf[start] to log_buf[end - 1]. | |
ac751efa | 1699 | * The console_lock must be held. |
1da177e4 | 1700 | */ |
d9c23523 | 1701 | static void call_console_drivers(const char *ext_text, size_t ext_len, |
6fe29354 | 1702 | const char *text, size_t len) |
1da177e4 | 1703 | { |
7ff9554b | 1704 | struct console *con; |
1da177e4 | 1705 | |
fc98c3c8 | 1706 | trace_console_rcuidle(text, len); |
7ff9554b | 1707 | |
7ff9554b KS |
1708 | if (!console_drivers) |
1709 | return; | |
1710 | ||
1711 | for_each_console(con) { | |
1712 | if (exclusive_console && con != exclusive_console) | |
1713 | continue; | |
1714 | if (!(con->flags & CON_ENABLED)) | |
1715 | continue; | |
1716 | if (!con->write) | |
1717 | continue; | |
1718 | if (!cpu_online(smp_processor_id()) && | |
1719 | !(con->flags & CON_ANYTIME)) | |
1720 | continue; | |
6fe29354 TH |
1721 | if (con->flags & CON_EXTENDED) |
1722 | con->write(con, ext_text, ext_len); | |
1723 | else | |
1724 | con->write(con, text, len); | |
7ff9554b | 1725 | } |
1da177e4 LT |
1726 | } |
1727 | ||
af91322e DY |
1728 | int printk_delay_msec __read_mostly; |
1729 | ||
1730 | static inline void printk_delay(void) | |
1731 | { | |
1732 | if (unlikely(printk_delay_msec)) { | |
1733 | int m = printk_delay_msec; | |
1734 | ||
1735 | while (m--) { | |
1736 | mdelay(1); | |
1737 | touch_nmi_watchdog(); | |
1738 | } | |
1739 | } | |
1740 | } | |
1741 | ||
084681d1 KS |
1742 | /* |
1743 | * Continuation lines are buffered, and not committed to the record buffer | |
1744 | * until the line is complete, or a race forces it. The line fragments | |
1745 | * though, are printed immediately to the consoles to ensure everything has | |
1746 | * reached the console in case of a kernel crash. | |
1747 | */ | |
1748 | static struct cont { | |
1749 | char buf[LOG_LINE_MAX]; | |
1750 | size_t len; /* length == 0 means unused buffer */ | |
084681d1 KS |
1751 | struct task_struct *owner; /* task of first print*/ |
1752 | u64 ts_nsec; /* time of first print */ | |
1753 | u8 level; /* log level of first message */ | |
0b90fec3 | 1754 | u8 facility; /* log facility of first message */ |
eab07260 | 1755 | enum log_flags flags; /* prefix, newline flags */ |
084681d1 KS |
1756 | } cont; |
1757 | ||
5e467652 | 1758 | static void cont_flush(void) |
084681d1 | 1759 | { |
084681d1 KS |
1760 | if (cont.len == 0) |
1761 | return; | |
5c2992ee LT |
1762 | |
1763 | log_store(cont.facility, cont.level, cont.flags, cont.ts_nsec, | |
1764 | NULL, 0, cont.buf, cont.len); | |
1765 | cont.len = 0; | |
084681d1 KS |
1766 | } |
1767 | ||
5e467652 | 1768 | static bool cont_add(int facility, int level, enum log_flags flags, const char *text, size_t len) |
084681d1 | 1769 | { |
6fe29354 TH |
1770 | /* |
1771 | * If ext consoles are present, flush and skip in-kernel | |
1772 | * continuation. See nr_ext_console_drivers definition. Also, if | |
1773 | * the line gets too long, split it up in separate records. | |
1774 | */ | |
1775 | if (nr_ext_console_drivers || cont.len + len > sizeof(cont.buf)) { | |
5e467652 | 1776 | cont_flush(); |
084681d1 KS |
1777 | return false; |
1778 | } | |
1779 | ||
1780 | if (!cont.len) { | |
1781 | cont.facility = facility; | |
1782 | cont.level = level; | |
1783 | cont.owner = current; | |
1784 | cont.ts_nsec = local_clock(); | |
5e467652 | 1785 | cont.flags = flags; |
084681d1 KS |
1786 | } |
1787 | ||
1788 | memcpy(cont.buf + cont.len, text, len); | |
1789 | cont.len += len; | |
eab07260 | 1790 | |
5e467652 LT |
1791 | // The original flags come from the first line, |
1792 | // but later continuations can add a newline. | |
1793 | if (flags & LOG_NEWLINE) { | |
1794 | cont.flags |= LOG_NEWLINE; | |
1795 | cont_flush(); | |
1796 | } | |
1797 | ||
eab07260 | 1798 | if (cont.len > (sizeof(cont.buf) * 80) / 100) |
5e467652 | 1799 | cont_flush(); |
eab07260 | 1800 | |
084681d1 KS |
1801 | return true; |
1802 | } | |
1803 | ||
c362c7ff LT |
1804 | 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) |
1805 | { | |
c362c7ff | 1806 | /* |
5e467652 LT |
1807 | * If an earlier line was buffered, and we're a continuation |
1808 | * write from the same process, try to add it to the buffer. | |
c362c7ff LT |
1809 | */ |
1810 | if (cont.len) { | |
5e467652 LT |
1811 | if (cont.owner == current && (lflags & LOG_CONT)) { |
1812 | if (cont_add(facility, level, lflags, text, text_len)) | |
1813 | return text_len; | |
1814 | } | |
1815 | /* Otherwise, make sure it's flushed */ | |
1816 | cont_flush(); | |
1817 | } | |
c362c7ff | 1818 | |
8835ca59 LT |
1819 | /* Skip empty continuation lines that couldn't be added - they just flush */ |
1820 | if (!text_len && (lflags & LOG_CONT)) | |
1821 | return 0; | |
1822 | ||
5e467652 LT |
1823 | /* If it doesn't end in a newline, try to buffer the current line */ |
1824 | if (!(lflags & LOG_NEWLINE)) { | |
1825 | if (cont_add(facility, level, lflags, text, text_len)) | |
c362c7ff LT |
1826 | return text_len; |
1827 | } | |
1828 | ||
5e467652 | 1829 | /* Store it in the record log */ |
c362c7ff LT |
1830 | return log_store(facility, level, lflags, 0, dict, dictlen, text, text_len); |
1831 | } | |
1832 | ||
ba552399 PM |
1833 | /* Must be called under logbuf_lock. */ |
1834 | int vprintk_store(int facility, int level, | |
1835 | const char *dict, size_t dictlen, | |
1836 | const char *fmt, va_list args) | |
1da177e4 | 1837 | { |
7ff9554b KS |
1838 | static char textbuf[LOG_LINE_MAX]; |
1839 | char *text = textbuf; | |
aec47caa | 1840 | size_t text_len; |
5becfb1d | 1841 | enum log_flags lflags = 0; |
bfe8df3d | 1842 | |
7ff9554b KS |
1843 | /* |
1844 | * The printf needs to come first; we need the syslog | |
1845 | * prefix which might be passed-in as a parameter. | |
1846 | */ | |
98e35f58 | 1847 | text_len = vscnprintf(text, sizeof(textbuf), fmt, args); |
5fd29d6c | 1848 | |
7ff9554b | 1849 | /* mark and strip a trailing newline */ |
c313af14 KS |
1850 | if (text_len && text[text_len-1] == '\n') { |
1851 | text_len--; | |
5becfb1d | 1852 | lflags |= LOG_NEWLINE; |
7ff9554b | 1853 | } |
9d90c8d9 | 1854 | |
088a52aa JP |
1855 | /* strip kernel syslog prefix and extract log level or control flags */ |
1856 | if (facility == 0) { | |
4bcc595c | 1857 | int kern_level; |
088a52aa | 1858 | |
4bcc595c | 1859 | while ((kern_level = printk_get_level(text)) != 0) { |
088a52aa JP |
1860 | switch (kern_level) { |
1861 | case '0' ... '7': | |
a39d4a85 | 1862 | if (level == LOGLEVEL_DEFAULT) |
088a52aa | 1863 | level = kern_level - '0'; |
a39d4a85 | 1864 | /* fallthrough */ |
088a52aa JP |
1865 | case 'd': /* KERN_DEFAULT */ |
1866 | lflags |= LOG_PREFIX; | |
4bcc595c LT |
1867 | break; |
1868 | case 'c': /* KERN_CONT */ | |
1869 | lflags |= LOG_CONT; | |
088a52aa | 1870 | } |
4bcc595c LT |
1871 | |
1872 | text_len -= 2; | |
1873 | text += 2; | |
5fd29d6c LT |
1874 | } |
1875 | } | |
1876 | ||
a39d4a85 | 1877 | if (level == LOGLEVEL_DEFAULT) |
c313af14 | 1878 | level = default_message_loglevel; |
9d90c8d9 | 1879 | |
5becfb1d KS |
1880 | if (dict) |
1881 | lflags |= LOG_PREFIX|LOG_NEWLINE; | |
ac60ad74 | 1882 | |
ba552399 PM |
1883 | return log_output(facility, level, lflags, |
1884 | dict, dictlen, text, text_len); | |
1885 | } | |
1da177e4 | 1886 | |
ba552399 PM |
1887 | asmlinkage int vprintk_emit(int facility, int level, |
1888 | const char *dict, size_t dictlen, | |
1889 | const char *fmt, va_list args) | |
1890 | { | |
1891 | int printed_len; | |
1892 | bool in_sched = false; | |
1893 | unsigned long flags; | |
1894 | ||
1895 | if (level == LOGLEVEL_SCHED) { | |
1896 | level = LOGLEVEL_DEFAULT; | |
1897 | in_sched = true; | |
1898 | } | |
1899 | ||
1900 | boot_delay_msec(level); | |
1901 | printk_delay(); | |
1902 | ||
1903 | /* This stops the holder of console_sem just where we want him */ | |
1904 | logbuf_lock_irqsave(flags); | |
1905 | printed_len = vprintk_store(facility, level, dict, dictlen, fmt, args); | |
de6fcbdb | 1906 | logbuf_unlock_irqrestore(flags); |
939f04be | 1907 | |
458df9fd | 1908 | /* If called from the scheduler, we can not call up(). */ |
d18bbc21 | 1909 | if (!in_sched) { |
fd5f7cde SS |
1910 | /* |
1911 | * Disable preemption to avoid being preempted while holding | |
1912 | * console_sem which would prevent anyone from printing to | |
1913 | * console | |
1914 | */ | |
1915 | preempt_disable(); | |
d18bbc21 AM |
1916 | /* |
1917 | * Try to acquire and then immediately release the console | |
1918 | * semaphore. The release will print out buffers and wake up | |
1919 | * /dev/kmsg and syslog() users. | |
1920 | */ | |
c162d5b4 | 1921 | if (console_trylock_spinning()) |
d18bbc21 | 1922 | console_unlock(); |
fd5f7cde | 1923 | preempt_enable(); |
d18bbc21 | 1924 | } |
76a8ad29 | 1925 | |
43a17111 | 1926 | wake_up_klogd(); |
1da177e4 LT |
1927 | return printed_len; |
1928 | } | |
7ff9554b KS |
1929 | EXPORT_SYMBOL(vprintk_emit); |
1930 | ||
1931 | asmlinkage int vprintk(const char *fmt, va_list args) | |
1932 | { | |
bd66a892 | 1933 | return vprintk_func(fmt, args); |
7ff9554b | 1934 | } |
1da177e4 LT |
1935 | EXPORT_SYMBOL(vprintk); |
1936 | ||
7ff9554b KS |
1937 | asmlinkage int printk_emit(int facility, int level, |
1938 | const char *dict, size_t dictlen, | |
1939 | const char *fmt, ...) | |
1940 | { | |
1941 | va_list args; | |
1942 | int r; | |
1943 | ||
1944 | va_start(args, fmt); | |
1945 | r = vprintk_emit(facility, level, dict, dictlen, fmt, args); | |
1946 | va_end(args); | |
1947 | ||
1948 | return r; | |
1949 | } | |
1950 | EXPORT_SYMBOL(printk_emit); | |
1951 | ||
a0cba217 | 1952 | int vprintk_default(const char *fmt, va_list args) |
afdc34a3 SRRH |
1953 | { |
1954 | int r; | |
1955 | ||
1956 | #ifdef CONFIG_KGDB_KDB | |
34aaff40 PM |
1957 | /* Allow to pass printk() to kdb but avoid a recursion. */ |
1958 | if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) { | |
f7d4ca8b | 1959 | r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args); |
afdc34a3 SRRH |
1960 | return r; |
1961 | } | |
1962 | #endif | |
a0cba217 | 1963 | r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); |
afdc34a3 SRRH |
1964 | |
1965 | return r; | |
1966 | } | |
1967 | EXPORT_SYMBOL_GPL(vprintk_default); | |
1968 | ||
7ff9554b KS |
1969 | /** |
1970 | * printk - print a kernel message | |
1971 | * @fmt: format string | |
1972 | * | |
1973 | * This is printk(). It can be called from any context. We want it to work. | |
1974 | * | |
1975 | * We try to grab the console_lock. If we succeed, it's easy - we log the | |
1976 | * output and call the console drivers. If we fail to get the semaphore, we | |
1977 | * place the output into the log buffer and return. The current holder of | |
1978 | * the console_sem will notice the new output in console_unlock(); and will | |
1979 | * send it to the consoles before releasing the lock. | |
1980 | * | |
1981 | * One effect of this deferred printing is that code which calls printk() and | |
1982 | * then changes console_loglevel may break. This is because console_loglevel | |
1983 | * is inspected when the actual printing occurs. | |
1984 | * | |
1985 | * See also: | |
1986 | * printf(3) | |
1987 | * | |
1988 | * See the vsnprintf() documentation for format string extensions over C99. | |
1989 | */ | |
722a9f92 | 1990 | asmlinkage __visible int printk(const char *fmt, ...) |
7ff9554b KS |
1991 | { |
1992 | va_list args; | |
1993 | int r; | |
1994 | ||
7ff9554b | 1995 | va_start(args, fmt); |
a0cba217 | 1996 | r = vprintk_func(fmt, args); |
7ff9554b KS |
1997 | va_end(args); |
1998 | ||
1999 | return r; | |
2000 | } | |
2001 | EXPORT_SYMBOL(printk); | |
7f3a781d | 2002 | |
96efedf1 | 2003 | #else /* CONFIG_PRINTK */ |
d59745ce | 2004 | |
70498253 KS |
2005 | #define LOG_LINE_MAX 0 |
2006 | #define PREFIX_MAX 0 | |
249771b8 | 2007 | |
96efedf1 KS |
2008 | static u64 syslog_seq; |
2009 | static u32 syslog_idx; | |
eab07260 KS |
2010 | static u64 console_seq; |
2011 | static u32 console_idx; | |
96efedf1 KS |
2012 | static u64 log_first_seq; |
2013 | static u32 log_first_idx; | |
2014 | static u64 log_next_seq; | |
6fe29354 TH |
2015 | static char *log_text(const struct printk_log *msg) { return NULL; } |
2016 | static char *log_dict(const struct printk_log *msg) { return NULL; } | |
62e32ac3 | 2017 | static struct printk_log *log_from_idx(u32 idx) { return NULL; } |
7f3a781d | 2018 | static u32 log_next(u32 idx) { return 0; } |
6fe29354 | 2019 | static ssize_t msg_print_ext_header(char *buf, size_t size, |
5aa068ea LT |
2020 | struct printk_log *msg, |
2021 | u64 seq) { return 0; } | |
6fe29354 TH |
2022 | static ssize_t msg_print_ext_body(char *buf, size_t size, |
2023 | char *dict, size_t dict_len, | |
2024 | char *text, size_t text_len) { return 0; } | |
c162d5b4 PM |
2025 | static void console_lock_spinning_enable(void) { } |
2026 | static int console_lock_spinning_disable_and_check(void) { return 0; } | |
d9c23523 | 2027 | static void call_console_drivers(const char *ext_text, size_t ext_len, |
6fe29354 | 2028 | const char *text, size_t len) {} |
5aa068ea | 2029 | static size_t msg_print_text(const struct printk_log *msg, |
5becfb1d | 2030 | bool syslog, char *buf, size_t size) { return 0; } |
a6ae928c | 2031 | static bool suppress_message_printing(int level) { return false; } |
d59745ce | 2032 | |
7f3a781d | 2033 | #endif /* CONFIG_PRINTK */ |
d59745ce | 2034 | |
d0380e6c TG |
2035 | #ifdef CONFIG_EARLY_PRINTK |
2036 | struct console *early_console; | |
2037 | ||
722a9f92 | 2038 | asmlinkage __visible void early_printk(const char *fmt, ...) |
d0380e6c TG |
2039 | { |
2040 | va_list ap; | |
1dc6244b JP |
2041 | char buf[512]; |
2042 | int n; | |
2043 | ||
2044 | if (!early_console) | |
2045 | return; | |
d0380e6c TG |
2046 | |
2047 | va_start(ap, fmt); | |
1dc6244b | 2048 | n = vscnprintf(buf, sizeof(buf), fmt, ap); |
d0380e6c | 2049 | va_end(ap); |
1dc6244b JP |
2050 | |
2051 | early_console->write(early_console, buf, n); | |
d0380e6c TG |
2052 | } |
2053 | #endif | |
2054 | ||
f7511d5f ST |
2055 | static int __add_preferred_console(char *name, int idx, char *options, |
2056 | char *brl_options) | |
2057 | { | |
2058 | struct console_cmdline *c; | |
2059 | int i; | |
2060 | ||
2061 | /* | |
2062 | * See if this tty is not yet registered, and | |
2063 | * if we have a slot free. | |
2064 | */ | |
dac8bbba PM |
2065 | for (i = 0, c = console_cmdline; |
2066 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2067 | i++, c++) { | |
23475408 | 2068 | if (strcmp(c->name, name) == 0 && c->index == idx) { |
dac8bbba PM |
2069 | if (!brl_options) |
2070 | preferred_console = i; | |
23475408 | 2071 | return 0; |
f7511d5f | 2072 | } |
23475408 | 2073 | } |
f7511d5f ST |
2074 | if (i == MAX_CMDLINECONSOLES) |
2075 | return -E2BIG; | |
2076 | if (!brl_options) | |
ad86ee2b | 2077 | preferred_console = i; |
f7511d5f ST |
2078 | strlcpy(c->name, name, sizeof(c->name)); |
2079 | c->options = options; | |
bbeddf52 JP |
2080 | braille_set_options(c, brl_options); |
2081 | ||
f7511d5f ST |
2082 | c->index = idx; |
2083 | return 0; | |
2084 | } | |
cca10d58 SS |
2085 | |
2086 | static int __init console_msg_format_setup(char *str) | |
2087 | { | |
2088 | if (!strcmp(str, "syslog")) | |
2089 | console_msg_format = MSG_FORMAT_SYSLOG; | |
2090 | if (!strcmp(str, "default")) | |
2091 | console_msg_format = MSG_FORMAT_DEFAULT; | |
2092 | return 1; | |
2093 | } | |
2094 | __setup("console_msg_format=", console_msg_format_setup); | |
2095 | ||
2ea1c539 | 2096 | /* |
0b90fec3 AE |
2097 | * Set up a console. Called via do_early_param() in init/main.c |
2098 | * for each "console=" parameter in the boot command line. | |
2ea1c539 JB |
2099 | */ |
2100 | static int __init console_setup(char *str) | |
2101 | { | |
0b90fec3 | 2102 | char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ |
f7511d5f | 2103 | char *s, *options, *brl_options = NULL; |
2ea1c539 JB |
2104 | int idx; |
2105 | ||
bbeddf52 JP |
2106 | if (_braille_console_setup(&str, &brl_options)) |
2107 | return 1; | |
f7511d5f | 2108 | |
2ea1c539 JB |
2109 | /* |
2110 | * Decode str into name, index, options. | |
2111 | */ | |
2112 | if (str[0] >= '0' && str[0] <= '9') { | |
eaa944af YL |
2113 | strcpy(buf, "ttyS"); |
2114 | strncpy(buf + 4, str, sizeof(buf) - 5); | |
2ea1c539 | 2115 | } else { |
eaa944af | 2116 | strncpy(buf, str, sizeof(buf) - 1); |
2ea1c539 | 2117 | } |
eaa944af | 2118 | buf[sizeof(buf) - 1] = 0; |
249771b8 AE |
2119 | options = strchr(str, ','); |
2120 | if (options) | |
2ea1c539 JB |
2121 | *(options++) = 0; |
2122 | #ifdef __sparc__ | |
2123 | if (!strcmp(str, "ttya")) | |
eaa944af | 2124 | strcpy(buf, "ttyS0"); |
2ea1c539 | 2125 | if (!strcmp(str, "ttyb")) |
eaa944af | 2126 | strcpy(buf, "ttyS1"); |
2ea1c539 | 2127 | #endif |
eaa944af | 2128 | for (s = buf; *s; s++) |
249771b8 | 2129 | if (isdigit(*s) || *s == ',') |
2ea1c539 JB |
2130 | break; |
2131 | idx = simple_strtoul(s, NULL, 10); | |
2132 | *s = 0; | |
2133 | ||
f7511d5f | 2134 | __add_preferred_console(buf, idx, options, brl_options); |
9e124fe1 | 2135 | console_set_on_cmdline = 1; |
2ea1c539 JB |
2136 | return 1; |
2137 | } | |
2138 | __setup("console=", console_setup); | |
2139 | ||
3c0547ba MM |
2140 | /** |
2141 | * add_preferred_console - add a device to the list of preferred consoles. | |
ddad86c2 MW |
2142 | * @name: device name |
2143 | * @idx: device index | |
2144 | * @options: options for this console | |
3c0547ba MM |
2145 | * |
2146 | * The last preferred console added will be used for kernel messages | |
2147 | * and stdin/out/err for init. Normally this is used by console_setup | |
2148 | * above to handle user-supplied console arguments; however it can also | |
2149 | * be used by arch-specific code either to override the user or more | |
2150 | * commonly to provide a default console (ie from PROM variables) when | |
2151 | * the user has not supplied one. | |
2152 | */ | |
fb445ee5 | 2153 | int add_preferred_console(char *name, int idx, char *options) |
3c0547ba | 2154 | { |
f7511d5f | 2155 | return __add_preferred_console(name, idx, options, NULL); |
3c0547ba MM |
2156 | } |
2157 | ||
d25d9fec | 2158 | bool console_suspend_enabled = true; |
8f4ce8c3 AS |
2159 | EXPORT_SYMBOL(console_suspend_enabled); |
2160 | ||
2161 | static int __init console_suspend_disable(char *str) | |
2162 | { | |
d25d9fec | 2163 | console_suspend_enabled = false; |
8f4ce8c3 AS |
2164 | return 1; |
2165 | } | |
2166 | __setup("no_console_suspend", console_suspend_disable); | |
134620f7 YZ |
2167 | module_param_named(console_suspend, console_suspend_enabled, |
2168 | bool, S_IRUGO | S_IWUSR); | |
2169 | MODULE_PARM_DESC(console_suspend, "suspend console during suspend" | |
2170 | " and hibernate operations"); | |
8f4ce8c3 | 2171 | |
557240b4 LT |
2172 | /** |
2173 | * suspend_console - suspend the console subsystem | |
2174 | * | |
2175 | * This disables printk() while we go into suspend states | |
2176 | */ | |
2177 | void suspend_console(void) | |
2178 | { | |
8f4ce8c3 AS |
2179 | if (!console_suspend_enabled) |
2180 | return; | |
47319f71 | 2181 | pr_info("Suspending console(s) (use no_console_suspend to debug)\n"); |
ac751efa | 2182 | console_lock(); |
557240b4 | 2183 | console_suspended = 1; |
bd8d7cf5 | 2184 | up_console_sem(); |
557240b4 LT |
2185 | } |
2186 | ||
2187 | void resume_console(void) | |
2188 | { | |
8f4ce8c3 AS |
2189 | if (!console_suspend_enabled) |
2190 | return; | |
bd8d7cf5 | 2191 | down_console_sem(); |
557240b4 | 2192 | console_suspended = 0; |
ac751efa | 2193 | console_unlock(); |
557240b4 LT |
2194 | } |
2195 | ||
034260d6 KC |
2196 | /** |
2197 | * console_cpu_notify - print deferred console messages after CPU hotplug | |
90b14889 | 2198 | * @cpu: unused |
034260d6 KC |
2199 | * |
2200 | * If printk() is called from a CPU that is not online yet, the messages | |
64ca752d SS |
2201 | * will be printed on the console only if there are CON_ANYTIME consoles. |
2202 | * This function is called when a new CPU comes online (or fails to come | |
2203 | * up) or goes offline. | |
034260d6 | 2204 | */ |
90b14889 SAS |
2205 | static int console_cpu_notify(unsigned int cpu) |
2206 | { | |
f97960fb | 2207 | if (!cpuhp_tasks_frozen) { |
64ca752d SS |
2208 | /* If trylock fails, someone else is doing the printing */ |
2209 | if (console_trylock()) | |
2210 | console_unlock(); | |
034260d6 | 2211 | } |
90b14889 | 2212 | return 0; |
034260d6 KC |
2213 | } |
2214 | ||
1da177e4 | 2215 | /** |
ac751efa | 2216 | * console_lock - lock the console system for exclusive use. |
1da177e4 | 2217 | * |
ac751efa | 2218 | * Acquires a lock which guarantees that the caller has |
1da177e4 LT |
2219 | * exclusive access to the console system and the console_drivers list. |
2220 | * | |
2221 | * Can sleep, returns nothing. | |
2222 | */ | |
ac751efa | 2223 | void console_lock(void) |
1da177e4 | 2224 | { |
6b898c07 DV |
2225 | might_sleep(); |
2226 | ||
bd8d7cf5 | 2227 | down_console_sem(); |
403f3075 AH |
2228 | if (console_suspended) |
2229 | return; | |
1da177e4 LT |
2230 | console_locked = 1; |
2231 | console_may_schedule = 1; | |
2232 | } | |
ac751efa | 2233 | EXPORT_SYMBOL(console_lock); |
1da177e4 | 2234 | |
ac751efa TH |
2235 | /** |
2236 | * console_trylock - try to lock the console system for exclusive use. | |
2237 | * | |
0b90fec3 AE |
2238 | * Try to acquire a lock which guarantees that the caller has exclusive |
2239 | * access to the console system and the console_drivers list. | |
ac751efa TH |
2240 | * |
2241 | * returns 1 on success, and 0 on failure to acquire the lock. | |
2242 | */ | |
2243 | int console_trylock(void) | |
1da177e4 | 2244 | { |
bd8d7cf5 | 2245 | if (down_trylock_console_sem()) |
ac751efa | 2246 | return 0; |
403f3075 | 2247 | if (console_suspended) { |
bd8d7cf5 | 2248 | up_console_sem(); |
ac751efa | 2249 | return 0; |
403f3075 | 2250 | } |
1da177e4 | 2251 | console_locked = 1; |
fd5f7cde | 2252 | console_may_schedule = 0; |
ac751efa | 2253 | return 1; |
1da177e4 | 2254 | } |
ac751efa | 2255 | EXPORT_SYMBOL(console_trylock); |
1da177e4 LT |
2256 | |
2257 | int is_console_locked(void) | |
2258 | { | |
2259 | return console_locked; | |
2260 | } | |
d48de54a | 2261 | EXPORT_SYMBOL(is_console_locked); |
1da177e4 | 2262 | |
a8199371 SS |
2263 | /* |
2264 | * Check if we have any console that is capable of printing while cpu is | |
2265 | * booting or shutting down. Requires console_sem. | |
2266 | */ | |
2267 | static int have_callable_console(void) | |
2268 | { | |
2269 | struct console *con; | |
2270 | ||
2271 | for_each_console(con) | |
adaf6590 SS |
2272 | if ((con->flags & CON_ENABLED) && |
2273 | (con->flags & CON_ANYTIME)) | |
a8199371 SS |
2274 | return 1; |
2275 | ||
2276 | return 0; | |
2277 | } | |
2278 | ||
2279 | /* | |
2280 | * Can we actually use the console at this time on this cpu? | |
2281 | * | |
2282 | * Console drivers may assume that per-cpu resources have been allocated. So | |
2283 | * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't | |
2284 | * call them until this CPU is officially up. | |
2285 | */ | |
2286 | static inline int can_use_console(void) | |
2287 | { | |
2288 | return cpu_online(raw_smp_processor_id()) || have_callable_console(); | |
2289 | } | |
2290 | ||
1da177e4 | 2291 | /** |
ac751efa | 2292 | * console_unlock - unlock the console system |
1da177e4 | 2293 | * |
ac751efa | 2294 | * Releases the console_lock which the caller holds on the console system |
1da177e4 LT |
2295 | * and the console driver list. |
2296 | * | |
ac751efa TH |
2297 | * While the console_lock was held, console output may have been buffered |
2298 | * by printk(). If this is the case, console_unlock(); emits | |
2299 | * the output prior to releasing the lock. | |
1da177e4 | 2300 | * |
7f3a781d | 2301 | * If there is output waiting, we wake /dev/kmsg and syslog() users. |
1da177e4 | 2302 | * |
ac751efa | 2303 | * console_unlock(); may be called from any context. |
1da177e4 | 2304 | */ |
ac751efa | 2305 | void console_unlock(void) |
1da177e4 | 2306 | { |
6fe29354 | 2307 | static char ext_text[CONSOLE_EXT_LOG_MAX]; |
70498253 | 2308 | static char text[LOG_LINE_MAX + PREFIX_MAX]; |
1da177e4 | 2309 | unsigned long flags; |
8d91f8b1 | 2310 | bool do_cond_resched, retry; |
1da177e4 | 2311 | |
557240b4 | 2312 | if (console_suspended) { |
bd8d7cf5 | 2313 | up_console_sem(); |
557240b4 LT |
2314 | return; |
2315 | } | |
78944e54 | 2316 | |
8d91f8b1 | 2317 | /* |
257ab443 | 2318 | * Console drivers are called with interrupts disabled, so |
8d91f8b1 TH |
2319 | * @console_may_schedule should be cleared before; however, we may |
2320 | * end up dumping a lot of lines, for example, if called from | |
2321 | * console registration path, and should invoke cond_resched() | |
2322 | * between lines if allowable. Not doing so can cause a very long | |
2323 | * scheduling stall on a slow console leading to RCU stall and | |
2324 | * softlockup warnings which exacerbate the issue with more | |
2325 | * messages practically incapacitating the system. | |
257ab443 PM |
2326 | * |
2327 | * console_trylock() is not able to detect the preemptive | |
2328 | * context reliably. Therefore the value must be stored before | |
2329 | * and cleared after the the "again" goto label. | |
8d91f8b1 TH |
2330 | */ |
2331 | do_cond_resched = console_may_schedule; | |
257ab443 | 2332 | again: |
78944e54 AD |
2333 | console_may_schedule = 0; |
2334 | ||
a8199371 SS |
2335 | /* |
2336 | * We released the console_sem lock, so we need to recheck if | |
2337 | * cpu is online and (if not) is there at least one CON_ANYTIME | |
2338 | * console. | |
2339 | */ | |
2340 | if (!can_use_console()) { | |
2341 | console_locked = 0; | |
2342 | up_console_sem(); | |
2343 | return; | |
2344 | } | |
2345 | ||
7ff9554b | 2346 | for (;;) { |
62e32ac3 | 2347 | struct printk_log *msg; |
6fe29354 | 2348 | size_t ext_len = 0; |
3ce9a7c0 | 2349 | size_t len; |
7ff9554b | 2350 | |
f975237b SS |
2351 | printk_safe_enter_irqsave(flags); |
2352 | raw_spin_lock(&logbuf_lock); | |
7ff9554b | 2353 | if (console_seq < log_first_seq) { |
9afe77ed | 2354 | len = sprintf(text, "** %u printk messages dropped **\n", |
84b5ec8a WD |
2355 | (unsigned)(log_first_seq - console_seq)); |
2356 | ||
7ff9554b KS |
2357 | /* messages are gone, move to first one */ |
2358 | console_seq = log_first_seq; | |
2359 | console_idx = log_first_idx; | |
84b5ec8a WD |
2360 | } else { |
2361 | len = 0; | |
7ff9554b | 2362 | } |
084681d1 | 2363 | skip: |
7ff9554b KS |
2364 | if (console_seq == log_next_seq) |
2365 | break; | |
2366 | ||
2367 | msg = log_from_idx(console_idx); | |
a6ae928c | 2368 | if (suppress_message_printing(msg->level)) { |
084681d1 | 2369 | /* |
a6ae928c PM |
2370 | * Skip record we have buffered and already printed |
2371 | * directly to the console when we received it, and | |
2372 | * record that has level above the console loglevel. | |
084681d1 KS |
2373 | */ |
2374 | console_idx = log_next(console_idx); | |
2375 | console_seq++; | |
2376 | goto skip; | |
2377 | } | |
649e6ee3 | 2378 | |
cca10d58 SS |
2379 | len += msg_print_text(msg, |
2380 | console_msg_format & MSG_FORMAT_SYSLOG, | |
2381 | text + len, | |
2382 | sizeof(text) - len); | |
6fe29354 TH |
2383 | if (nr_ext_console_drivers) { |
2384 | ext_len = msg_print_ext_header(ext_text, | |
2385 | sizeof(ext_text), | |
5aa068ea | 2386 | msg, console_seq); |
6fe29354 TH |
2387 | ext_len += msg_print_ext_body(ext_text + ext_len, |
2388 | sizeof(ext_text) - ext_len, | |
2389 | log_dict(msg), msg->dict_len, | |
2390 | log_text(msg), msg->text_len); | |
2391 | } | |
7ff9554b KS |
2392 | console_idx = log_next(console_idx); |
2393 | console_seq++; | |
07354eb1 | 2394 | raw_spin_unlock(&logbuf_lock); |
7ff9554b | 2395 | |
dbdda842 SRV |
2396 | /* |
2397 | * While actively printing out messages, if another printk() | |
2398 | * were to occur on another CPU, it may wait for this one to | |
2399 | * finish. This task can not be preempted if there is a | |
2400 | * waiter waiting to take over. | |
2401 | */ | |
c162d5b4 | 2402 | console_lock_spinning_enable(); |
dbdda842 | 2403 | |
81d68a96 | 2404 | stop_critical_timings(); /* don't trace print latency */ |
d9c23523 | 2405 | call_console_drivers(ext_text, ext_len, text, len); |
81d68a96 | 2406 | start_critical_timings(); |
dbdda842 | 2407 | |
c162d5b4 PM |
2408 | if (console_lock_spinning_disable_and_check()) { |
2409 | printk_safe_exit_irqrestore(flags); | |
43a17111 | 2410 | return; |
c162d5b4 | 2411 | } |
dbdda842 | 2412 | |
f975237b | 2413 | printk_safe_exit_irqrestore(flags); |
8d91f8b1 TH |
2414 | |
2415 | if (do_cond_resched) | |
2416 | cond_resched(); | |
1da177e4 | 2417 | } |
dbdda842 | 2418 | |
1da177e4 | 2419 | console_locked = 0; |
fe3d8ad3 FT |
2420 | |
2421 | /* Release the exclusive_console once it is used */ | |
2422 | if (unlikely(exclusive_console)) | |
2423 | exclusive_console = NULL; | |
2424 | ||
07354eb1 | 2425 | raw_spin_unlock(&logbuf_lock); |
4f2a8d3c | 2426 | |
bd8d7cf5 | 2427 | up_console_sem(); |
4f2a8d3c PZ |
2428 | |
2429 | /* | |
2430 | * Someone could have filled up the buffer again, so re-check if there's | |
2431 | * something to flush. In case we cannot trylock the console_sem again, | |
2432 | * there's a new owner and the console_unlock() from them will do the | |
2433 | * flush, no worries. | |
2434 | */ | |
07354eb1 | 2435 | raw_spin_lock(&logbuf_lock); |
7ff9554b | 2436 | retry = console_seq != log_next_seq; |
f975237b SS |
2437 | raw_spin_unlock(&logbuf_lock); |
2438 | printk_safe_exit_irqrestore(flags); | |
09dc3cf9 | 2439 | |
4f2a8d3c PZ |
2440 | if (retry && console_trylock()) |
2441 | goto again; | |
1da177e4 | 2442 | } |
ac751efa | 2443 | EXPORT_SYMBOL(console_unlock); |
1da177e4 | 2444 | |
ddad86c2 MW |
2445 | /** |
2446 | * console_conditional_schedule - yield the CPU if required | |
1da177e4 LT |
2447 | * |
2448 | * If the console code is currently allowed to sleep, and | |
2449 | * if this CPU should yield the CPU to another task, do | |
2450 | * so here. | |
2451 | * | |
ac751efa | 2452 | * Must be called within console_lock();. |
1da177e4 LT |
2453 | */ |
2454 | void __sched console_conditional_schedule(void) | |
2455 | { | |
2456 | if (console_may_schedule) | |
2457 | cond_resched(); | |
2458 | } | |
2459 | EXPORT_SYMBOL(console_conditional_schedule); | |
2460 | ||
1da177e4 LT |
2461 | void console_unblank(void) |
2462 | { | |
2463 | struct console *c; | |
2464 | ||
2465 | /* | |
2466 | * console_unblank can no longer be called in interrupt context unless | |
2467 | * oops_in_progress is set to 1.. | |
2468 | */ | |
2469 | if (oops_in_progress) { | |
bd8d7cf5 | 2470 | if (down_trylock_console_sem() != 0) |
1da177e4 LT |
2471 | return; |
2472 | } else | |
ac751efa | 2473 | console_lock(); |
1da177e4 LT |
2474 | |
2475 | console_locked = 1; | |
2476 | console_may_schedule = 0; | |
4d091611 | 2477 | for_each_console(c) |
1da177e4 LT |
2478 | if ((c->flags & CON_ENABLED) && c->unblank) |
2479 | c->unblank(); | |
ac751efa | 2480 | console_unlock(); |
1da177e4 | 2481 | } |
1da177e4 | 2482 | |
8d91f8b1 TH |
2483 | /** |
2484 | * console_flush_on_panic - flush console content on panic | |
2485 | * | |
2486 | * Immediately output all pending messages no matter what. | |
2487 | */ | |
2488 | void console_flush_on_panic(void) | |
2489 | { | |
2490 | /* | |
2491 | * If someone else is holding the console lock, trylock will fail | |
2492 | * and may_schedule may be set. Ignore and proceed to unlock so | |
2493 | * that messages are flushed out. As this can be called from any | |
2494 | * context and we don't want to get preempted while flushing, | |
2495 | * ensure may_schedule is cleared. | |
2496 | */ | |
2497 | console_trylock(); | |
2498 | console_may_schedule = 0; | |
2499 | console_unlock(); | |
2500 | } | |
2501 | ||
1da177e4 LT |
2502 | /* |
2503 | * Return the console tty driver structure and its associated index | |
2504 | */ | |
2505 | struct tty_driver *console_device(int *index) | |
2506 | { | |
2507 | struct console *c; | |
2508 | struct tty_driver *driver = NULL; | |
2509 | ||
ac751efa | 2510 | console_lock(); |
4d091611 | 2511 | for_each_console(c) { |
1da177e4 LT |
2512 | if (!c->device) |
2513 | continue; | |
2514 | driver = c->device(c, index); | |
2515 | if (driver) | |
2516 | break; | |
2517 | } | |
ac751efa | 2518 | console_unlock(); |
1da177e4 LT |
2519 | return driver; |
2520 | } | |
2521 | ||
2522 | /* | |
2523 | * Prevent further output on the passed console device so that (for example) | |
2524 | * serial drivers can disable console output before suspending a port, and can | |
2525 | * re-enable output afterwards. | |
2526 | */ | |
2527 | void console_stop(struct console *console) | |
2528 | { | |
ac751efa | 2529 | console_lock(); |
1da177e4 | 2530 | console->flags &= ~CON_ENABLED; |
ac751efa | 2531 | console_unlock(); |
1da177e4 LT |
2532 | } |
2533 | EXPORT_SYMBOL(console_stop); | |
2534 | ||
2535 | void console_start(struct console *console) | |
2536 | { | |
ac751efa | 2537 | console_lock(); |
1da177e4 | 2538 | console->flags |= CON_ENABLED; |
ac751efa | 2539 | console_unlock(); |
1da177e4 LT |
2540 | } |
2541 | EXPORT_SYMBOL(console_start); | |
2542 | ||
7bf69395 FDN |
2543 | static int __read_mostly keep_bootcon; |
2544 | ||
2545 | static int __init keep_bootcon_setup(char *str) | |
2546 | { | |
2547 | keep_bootcon = 1; | |
27083bac | 2548 | pr_info("debug: skip boot console de-registration.\n"); |
7bf69395 FDN |
2549 | |
2550 | return 0; | |
2551 | } | |
2552 | ||
2553 | early_param("keep_bootcon", keep_bootcon_setup); | |
2554 | ||
1da177e4 LT |
2555 | /* |
2556 | * The console driver calls this routine during kernel initialization | |
2557 | * to register the console printing procedure with printk() and to | |
2558 | * print any messages that were printed by the kernel before the | |
2559 | * console driver was initialized. | |
4d091611 RG |
2560 | * |
2561 | * This can happen pretty early during the boot process (because of | |
2562 | * early_printk) - sometimes before setup_arch() completes - be careful | |
2563 | * of what kernel features are used - they may not be initialised yet. | |
2564 | * | |
2565 | * There are two types of consoles - bootconsoles (early_printk) and | |
2566 | * "real" consoles (everything which is not a bootconsole) which are | |
2567 | * handled differently. | |
2568 | * - Any number of bootconsoles can be registered at any time. | |
2569 | * - As soon as a "real" console is registered, all bootconsoles | |
2570 | * will be unregistered automatically. | |
2571 | * - Once a "real" console is registered, any attempt to register a | |
2572 | * bootconsoles will be rejected | |
1da177e4 | 2573 | */ |
4d091611 | 2574 | void register_console(struct console *newcon) |
1da177e4 | 2575 | { |
40dc5651 | 2576 | int i; |
1da177e4 | 2577 | unsigned long flags; |
4d091611 | 2578 | struct console *bcon = NULL; |
23475408 | 2579 | struct console_cmdline *c; |
b077bafa | 2580 | static bool has_preferred; |
1da177e4 | 2581 | |
16cf48a6 AB |
2582 | if (console_drivers) |
2583 | for_each_console(bcon) | |
2584 | if (WARN(bcon == newcon, | |
2585 | "console '%s%d' already registered\n", | |
2586 | bcon->name, bcon->index)) | |
2587 | return; | |
2588 | ||
4d091611 RG |
2589 | /* |
2590 | * before we register a new CON_BOOT console, make sure we don't | |
2591 | * already have a valid console | |
2592 | */ | |
2593 | if (console_drivers && newcon->flags & CON_BOOT) { | |
2594 | /* find the last or real console */ | |
2595 | for_each_console(bcon) { | |
2596 | if (!(bcon->flags & CON_BOOT)) { | |
27083bac | 2597 | pr_info("Too late to register bootconsole %s%d\n", |
4d091611 RG |
2598 | newcon->name, newcon->index); |
2599 | return; | |
2600 | } | |
2601 | } | |
69331af7 GH |
2602 | } |
2603 | ||
4d091611 RG |
2604 | if (console_drivers && console_drivers->flags & CON_BOOT) |
2605 | bcon = console_drivers; | |
2606 | ||
b077bafa | 2607 | if (!has_preferred || bcon || !console_drivers) |
ad86ee2b | 2608 | has_preferred = preferred_console >= 0; |
1da177e4 LT |
2609 | |
2610 | /* | |
2611 | * See if we want to use this console driver. If we | |
2612 | * didn't select a console we take the first one | |
2613 | * that registers here. | |
2614 | */ | |
b077bafa | 2615 | if (!has_preferred) { |
4d091611 RG |
2616 | if (newcon->index < 0) |
2617 | newcon->index = 0; | |
2618 | if (newcon->setup == NULL || | |
2619 | newcon->setup(newcon, NULL) == 0) { | |
2620 | newcon->flags |= CON_ENABLED; | |
2621 | if (newcon->device) { | |
2622 | newcon->flags |= CON_CONSDEV; | |
b077bafa | 2623 | has_preferred = true; |
cd3a1b85 | 2624 | } |
1da177e4 LT |
2625 | } |
2626 | } | |
2627 | ||
2628 | /* | |
dac8bbba PM |
2629 | * See if this console matches one we selected on |
2630 | * the command line. | |
1da177e4 | 2631 | */ |
dac8bbba PM |
2632 | for (i = 0, c = console_cmdline; |
2633 | i < MAX_CMDLINECONSOLES && c->name[0]; | |
2634 | i++, c++) { | |
c7cef0a8 PH |
2635 | if (!newcon->match || |
2636 | newcon->match(newcon, c->name, c->index, c->options) != 0) { | |
2637 | /* default matching */ | |
2638 | BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name)); | |
2639 | if (strcmp(c->name, newcon->name) != 0) | |
2640 | continue; | |
2641 | if (newcon->index >= 0 && | |
2642 | newcon->index != c->index) | |
2643 | continue; | |
2644 | if (newcon->index < 0) | |
2645 | newcon->index = c->index; | |
bbeddf52 | 2646 | |
c7cef0a8 PH |
2647 | if (_braille_register_console(newcon, c)) |
2648 | return; | |
2649 | ||
2650 | if (newcon->setup && | |
2651 | newcon->setup(newcon, c->options) != 0) | |
2652 | break; | |
2653 | } | |
bbeddf52 | 2654 | |
4d091611 | 2655 | newcon->flags |= CON_ENABLED; |
ad86ee2b | 2656 | if (i == preferred_console) { |
4d091611 | 2657 | newcon->flags |= CON_CONSDEV; |
b077bafa | 2658 | has_preferred = true; |
ab4af03a | 2659 | } |
1da177e4 LT |
2660 | break; |
2661 | } | |
2662 | ||
4d091611 | 2663 | if (!(newcon->flags & CON_ENABLED)) |
1da177e4 LT |
2664 | return; |
2665 | ||
8259cf43 RG |
2666 | /* |
2667 | * If we have a bootconsole, and are switching to a real console, | |
2668 | * don't print everything out again, since when the boot console, and | |
2669 | * the real console are the same physical device, it's annoying to | |
2670 | * see the beginning boot messages twice | |
2671 | */ | |
2672 | if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) | |
4d091611 | 2673 | newcon->flags &= ~CON_PRINTBUFFER; |
1da177e4 LT |
2674 | |
2675 | /* | |
2676 | * Put this console in the list - keep the | |
2677 | * preferred driver at the head of the list. | |
2678 | */ | |
ac751efa | 2679 | console_lock(); |
4d091611 RG |
2680 | if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) { |
2681 | newcon->next = console_drivers; | |
2682 | console_drivers = newcon; | |
2683 | if (newcon->next) | |
2684 | newcon->next->flags &= ~CON_CONSDEV; | |
1da177e4 | 2685 | } else { |
4d091611 RG |
2686 | newcon->next = console_drivers->next; |
2687 | console_drivers->next = newcon; | |
1da177e4 | 2688 | } |
6fe29354 TH |
2689 | |
2690 | if (newcon->flags & CON_EXTENDED) | |
2691 | if (!nr_ext_console_drivers++) | |
2692 | pr_info("printk: continuation disabled due to ext consoles, expect more fragments in /dev/kmsg\n"); | |
2693 | ||
4d091611 | 2694 | if (newcon->flags & CON_PRINTBUFFER) { |
1da177e4 | 2695 | /* |
ac751efa | 2696 | * console_unlock(); will print out the buffered messages |
1da177e4 LT |
2697 | * for us. |
2698 | */ | |
de6fcbdb | 2699 | logbuf_lock_irqsave(flags); |
7ff9554b KS |
2700 | console_seq = syslog_seq; |
2701 | console_idx = syslog_idx; | |
de6fcbdb | 2702 | logbuf_unlock_irqrestore(flags); |
fe3d8ad3 FT |
2703 | /* |
2704 | * We're about to replay the log buffer. Only do this to the | |
2705 | * just-registered console to avoid excessive message spam to | |
2706 | * the already-registered consoles. | |
2707 | */ | |
2708 | exclusive_console = newcon; | |
1da177e4 | 2709 | } |
ac751efa | 2710 | console_unlock(); |
fbc92a34 | 2711 | console_sysfs_notify(); |
8259cf43 RG |
2712 | |
2713 | /* | |
2714 | * By unregistering the bootconsoles after we enable the real console | |
2715 | * we get the "console xxx enabled" message on all the consoles - | |
2716 | * boot consoles, real consoles, etc - this is to ensure that end | |
2717 | * users know there might be something in the kernel's log buffer that | |
2718 | * went to the bootconsole (that they do not see on the real console) | |
2719 | */ | |
27083bac | 2720 | pr_info("%sconsole [%s%d] enabled\n", |
6b802394 KC |
2721 | (newcon->flags & CON_BOOT) ? "boot" : "" , |
2722 | newcon->name, newcon->index); | |
7bf69395 FDN |
2723 | if (bcon && |
2724 | ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) && | |
2725 | !keep_bootcon) { | |
6b802394 KC |
2726 | /* We need to iterate through all boot consoles, to make |
2727 | * sure we print everything out, before we unregister them. | |
8259cf43 | 2728 | */ |
8259cf43 RG |
2729 | for_each_console(bcon) |
2730 | if (bcon->flags & CON_BOOT) | |
2731 | unregister_console(bcon); | |
8259cf43 | 2732 | } |
1da177e4 LT |
2733 | } |
2734 | EXPORT_SYMBOL(register_console); | |
2735 | ||
40dc5651 | 2736 | int unregister_console(struct console *console) |
1da177e4 | 2737 | { |
40dc5651 | 2738 | struct console *a, *b; |
bbeddf52 | 2739 | int res; |
1da177e4 | 2740 | |
27083bac | 2741 | pr_info("%sconsole [%s%d] disabled\n", |
6b802394 KC |
2742 | (console->flags & CON_BOOT) ? "boot" : "" , |
2743 | console->name, console->index); | |
2744 | ||
bbeddf52 JP |
2745 | res = _braille_unregister_console(console); |
2746 | if (res) | |
2747 | return res; | |
f7511d5f | 2748 | |
bbeddf52 | 2749 | res = 1; |
ac751efa | 2750 | console_lock(); |
1da177e4 LT |
2751 | if (console_drivers == console) { |
2752 | console_drivers=console->next; | |
2753 | res = 0; | |
e9b15b54 | 2754 | } else if (console_drivers) { |
1da177e4 LT |
2755 | for (a=console_drivers->next, b=console_drivers ; |
2756 | a; b=a, a=b->next) { | |
2757 | if (a == console) { | |
2758 | b->next = a->next; | |
2759 | res = 0; | |
2760 | break; | |
40dc5651 | 2761 | } |
1da177e4 LT |
2762 | } |
2763 | } | |
40dc5651 | 2764 | |
6fe29354 TH |
2765 | if (!res && (console->flags & CON_EXTENDED)) |
2766 | nr_ext_console_drivers--; | |
2767 | ||
69331af7 | 2768 | /* |
ab4af03a GE |
2769 | * If this isn't the last console and it has CON_CONSDEV set, we |
2770 | * need to set it on the next preferred console. | |
1da177e4 | 2771 | */ |
69331af7 | 2772 | if (console_drivers != NULL && console->flags & CON_CONSDEV) |
ab4af03a | 2773 | console_drivers->flags |= CON_CONSDEV; |
1da177e4 | 2774 | |
7fa21dd8 | 2775 | console->flags &= ~CON_ENABLED; |
ac751efa | 2776 | console_unlock(); |
fbc92a34 | 2777 | console_sysfs_notify(); |
1da177e4 LT |
2778 | return res; |
2779 | } | |
2780 | EXPORT_SYMBOL(unregister_console); | |
d59745ce | 2781 | |
0c688614 NP |
2782 | /* |
2783 | * Initialize the console device. This is called *early*, so | |
2784 | * we can't necessarily depend on lots of kernel help here. | |
2785 | * Just do some early initializations, and do the complex setup | |
2786 | * later. | |
2787 | */ | |
2788 | void __init console_init(void) | |
2789 | { | |
58eacfff | 2790 | int ret; |
1b1eeca7 AB |
2791 | initcall_t call; |
2792 | initcall_entry_t *ce; | |
0c688614 NP |
2793 | |
2794 | /* Setup the default TTY line discipline. */ | |
2795 | n_tty_init(); | |
2796 | ||
2797 | /* | |
2798 | * set up the console device so that later boot sequences can | |
2799 | * inform about problems etc.. | |
2800 | */ | |
1b1eeca7 | 2801 | ce = __con_initcall_start; |
58eacfff | 2802 | trace_initcall_level("console"); |
1b1eeca7 AB |
2803 | while (ce < __con_initcall_end) { |
2804 | call = initcall_from_entry(ce); | |
2805 | trace_initcall_start(call); | |
2806 | ret = call(); | |
2807 | trace_initcall_finish(call, ret); | |
2808 | ce++; | |
0c688614 NP |
2809 | } |
2810 | } | |
2811 | ||
81cc26f2 TR |
2812 | /* |
2813 | * Some boot consoles access data that is in the init section and which will | |
2814 | * be discarded after the initcalls have been run. To make sure that no code | |
2815 | * will access this data, unregister the boot consoles in a late initcall. | |
2816 | * | |
2817 | * If for some reason, such as deferred probe or the driver being a loadable | |
2818 | * module, the real console hasn't registered yet at this point, there will | |
2819 | * be a brief interval in which no messages are logged to the console, which | |
2820 | * makes it difficult to diagnose problems that occur during this time. | |
2821 | * | |
2822 | * To mitigate this problem somewhat, only unregister consoles whose memory | |
2b1be689 MR |
2823 | * intersects with the init section. Note that all other boot consoles will |
2824 | * get unregistred when the real preferred console is registered. | |
81cc26f2 | 2825 | */ |
034260d6 | 2826 | static int __init printk_late_init(void) |
0c5564bd | 2827 | { |
4d091611 | 2828 | struct console *con; |
90b14889 | 2829 | int ret; |
4d091611 RG |
2830 | |
2831 | for_each_console(con) { | |
5a814231 PM |
2832 | if (!(con->flags & CON_BOOT)) |
2833 | continue; | |
2834 | ||
2835 | /* Check addresses that might be used for enabled consoles. */ | |
2836 | if (init_section_intersects(con, sizeof(*con)) || | |
2837 | init_section_contains(con->write, 0) || | |
2838 | init_section_contains(con->read, 0) || | |
2839 | init_section_contains(con->device, 0) || | |
2840 | init_section_contains(con->unblank, 0) || | |
2841 | init_section_contains(con->data, 0)) { | |
81cc26f2 | 2842 | /* |
2b1be689 MR |
2843 | * Please, consider moving the reported consoles out |
2844 | * of the init section. | |
81cc26f2 | 2845 | */ |
2b1be689 MR |
2846 | pr_warn("bootconsole [%s%d] uses init memory and must be disabled even before the real one is ready\n", |
2847 | con->name, con->index); | |
2848 | unregister_console(con); | |
cb00e99c | 2849 | } |
0c5564bd | 2850 | } |
90b14889 SAS |
2851 | ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL, |
2852 | console_cpu_notify); | |
2853 | WARN_ON(ret < 0); | |
2854 | ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "printk:online", | |
2855 | console_cpu_notify, NULL); | |
2856 | WARN_ON(ret < 0); | |
0c5564bd RG |
2857 | return 0; |
2858 | } | |
034260d6 | 2859 | late_initcall(printk_late_init); |
0c5564bd | 2860 | |
7ef3d2fd | 2861 | #if defined CONFIG_PRINTK |
dc72c32e FW |
2862 | /* |
2863 | * Delayed printk version, for scheduler-internal messages: | |
2864 | */ | |
dc72c32e | 2865 | #define PRINTK_PENDING_WAKEUP 0x01 |
458df9fd | 2866 | #define PRINTK_PENDING_OUTPUT 0x02 |
dc72c32e FW |
2867 | |
2868 | static DEFINE_PER_CPU(int, printk_pending); | |
dc72c32e FW |
2869 | |
2870 | static void wake_up_klogd_work_func(struct irq_work *irq_work) | |
2871 | { | |
2872 | int pending = __this_cpu_xchg(printk_pending, 0); | |
2873 | ||
458df9fd SR |
2874 | if (pending & PRINTK_PENDING_OUTPUT) { |
2875 | /* If trylock fails, someone else is doing the printing */ | |
2876 | if (console_trylock()) | |
2877 | console_unlock(); | |
dc72c32e FW |
2878 | } |
2879 | ||
2880 | if (pending & PRINTK_PENDING_WAKEUP) | |
2881 | wake_up_interruptible(&log_wait); | |
2882 | } | |
2883 | ||
2884 | static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { | |
2885 | .func = wake_up_klogd_work_func, | |
2886 | .flags = IRQ_WORK_LAZY, | |
2887 | }; | |
2888 | ||
2889 | void wake_up_klogd(void) | |
2890 | { | |
2891 | preempt_disable(); | |
2892 | if (waitqueue_active(&log_wait)) { | |
2893 | this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); | |
bb964a92 | 2894 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
dc72c32e FW |
2895 | } |
2896 | preempt_enable(); | |
2897 | } | |
717115e1 | 2898 | |
a338f84d | 2899 | void defer_console_output(void) |
600e1458 | 2900 | { |
719f6a70 | 2901 | preempt_disable(); |
458df9fd | 2902 | __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); |
bb964a92 | 2903 | irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |
81954606 | 2904 | preempt_enable(); |
a338f84d PM |
2905 | } |
2906 | ||
2907 | int vprintk_deferred(const char *fmt, va_list args) | |
2908 | { | |
2909 | int r; | |
2910 | ||
2911 | r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args); | |
2912 | defer_console_output(); | |
600e1458 PZ |
2913 | |
2914 | return r; | |
2915 | } | |
2916 | ||
719f6a70 PM |
2917 | int printk_deferred(const char *fmt, ...) |
2918 | { | |
2919 | va_list args; | |
2920 | int r; | |
2921 | ||
2922 | va_start(args, fmt); | |
2923 | r = vprintk_deferred(fmt, args); | |
2924 | va_end(args); | |
2925 | ||
2926 | return r; | |
2927 | } | |
2928 | ||
1da177e4 LT |
2929 | /* |
2930 | * printk rate limiting, lifted from the networking subsystem. | |
2931 | * | |
641de9d8 UKK |
2932 | * This enforces a rate limit: not more than 10 kernel messages |
2933 | * every 5s to make a denial-of-service attack impossible. | |
1da177e4 | 2934 | */ |
641de9d8 UKK |
2935 | DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10); |
2936 | ||
5c828713 | 2937 | int __printk_ratelimit(const char *func) |
1da177e4 | 2938 | { |
5c828713 | 2939 | return ___ratelimit(&printk_ratelimit_state, func); |
1da177e4 | 2940 | } |
5c828713 | 2941 | EXPORT_SYMBOL(__printk_ratelimit); |
f46c4833 AM |
2942 | |
2943 | /** | |
2944 | * printk_timed_ratelimit - caller-controlled printk ratelimiting | |
2945 | * @caller_jiffies: pointer to caller's state | |
2946 | * @interval_msecs: minimum interval between prints | |
2947 | * | |
2948 | * printk_timed_ratelimit() returns true if more than @interval_msecs | |
2949 | * milliseconds have elapsed since the last time printk_timed_ratelimit() | |
2950 | * returned true. | |
2951 | */ | |
2952 | bool printk_timed_ratelimit(unsigned long *caller_jiffies, | |
2953 | unsigned int interval_msecs) | |
2954 | { | |
249771b8 AE |
2955 | unsigned long elapsed = jiffies - *caller_jiffies; |
2956 | ||
2957 | if (*caller_jiffies && elapsed <= msecs_to_jiffies(interval_msecs)) | |
2958 | return false; | |
2959 | ||
2960 | *caller_jiffies = jiffies; | |
2961 | return true; | |
f46c4833 AM |
2962 | } |
2963 | EXPORT_SYMBOL(printk_timed_ratelimit); | |
456b565c SK |
2964 | |
2965 | static DEFINE_SPINLOCK(dump_list_lock); | |
2966 | static LIST_HEAD(dump_list); | |
2967 | ||
2968 | /** | |
2969 | * kmsg_dump_register - register a kernel log dumper. | |
6485536b | 2970 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
2971 | * |
2972 | * Adds a kernel log dumper to the system. The dump callback in the | |
2973 | * structure will be called when the kernel oopses or panics and must be | |
2974 | * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise. | |
2975 | */ | |
2976 | int kmsg_dump_register(struct kmsg_dumper *dumper) | |
2977 | { | |
2978 | unsigned long flags; | |
2979 | int err = -EBUSY; | |
2980 | ||
2981 | /* The dump callback needs to be set */ | |
2982 | if (!dumper->dump) | |
2983 | return -EINVAL; | |
2984 | ||
2985 | spin_lock_irqsave(&dump_list_lock, flags); | |
2986 | /* Don't allow registering multiple times */ | |
2987 | if (!dumper->registered) { | |
2988 | dumper->registered = 1; | |
fb842b00 | 2989 | list_add_tail_rcu(&dumper->list, &dump_list); |
456b565c SK |
2990 | err = 0; |
2991 | } | |
2992 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
2993 | ||
2994 | return err; | |
2995 | } | |
2996 | EXPORT_SYMBOL_GPL(kmsg_dump_register); | |
2997 | ||
2998 | /** | |
2999 | * kmsg_dump_unregister - unregister a kmsg dumper. | |
6485536b | 3000 | * @dumper: pointer to the kmsg_dumper structure |
456b565c SK |
3001 | * |
3002 | * Removes a dump device from the system. Returns zero on success and | |
3003 | * %-EINVAL otherwise. | |
3004 | */ | |
3005 | int kmsg_dump_unregister(struct kmsg_dumper *dumper) | |
3006 | { | |
3007 | unsigned long flags; | |
3008 | int err = -EINVAL; | |
3009 | ||
3010 | spin_lock_irqsave(&dump_list_lock, flags); | |
3011 | if (dumper->registered) { | |
3012 | dumper->registered = 0; | |
fb842b00 | 3013 | list_del_rcu(&dumper->list); |
456b565c SK |
3014 | err = 0; |
3015 | } | |
3016 | spin_unlock_irqrestore(&dump_list_lock, flags); | |
fb842b00 | 3017 | synchronize_rcu(); |
456b565c SK |
3018 | |
3019 | return err; | |
3020 | } | |
3021 | EXPORT_SYMBOL_GPL(kmsg_dump_unregister); | |
3022 | ||
7ff9554b KS |
3023 | static bool always_kmsg_dump; |
3024 | module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); | |
3025 | ||
456b565c SK |
3026 | /** |
3027 | * kmsg_dump - dump kernel log to kernel message dumpers. | |
3028 | * @reason: the reason (oops, panic etc) for dumping | |
3029 | * | |
e2ae715d KS |
3030 | * Call each of the registered dumper's dump() callback, which can |
3031 | * retrieve the kmsg records with kmsg_dump_get_line() or | |
3032 | * kmsg_dump_get_buffer(). | |
456b565c SK |
3033 | */ |
3034 | void kmsg_dump(enum kmsg_dump_reason reason) | |
3035 | { | |
456b565c | 3036 | struct kmsg_dumper *dumper; |
456b565c SK |
3037 | unsigned long flags; |
3038 | ||
c22ab332 MG |
3039 | if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump) |
3040 | return; | |
3041 | ||
e2ae715d KS |
3042 | rcu_read_lock(); |
3043 | list_for_each_entry_rcu(dumper, &dump_list, list) { | |
3044 | if (dumper->max_reason && reason > dumper->max_reason) | |
3045 | continue; | |
3046 | ||
3047 | /* initialize iterator with data about the stored records */ | |
3048 | dumper->active = true; | |
3049 | ||
de6fcbdb | 3050 | logbuf_lock_irqsave(flags); |
e2ae715d KS |
3051 | dumper->cur_seq = clear_seq; |
3052 | dumper->cur_idx = clear_idx; | |
3053 | dumper->next_seq = log_next_seq; | |
3054 | dumper->next_idx = log_next_idx; | |
de6fcbdb | 3055 | logbuf_unlock_irqrestore(flags); |
e2ae715d KS |
3056 | |
3057 | /* invoke dumper which will iterate over records */ | |
3058 | dumper->dump(dumper, reason); | |
3059 | ||
3060 | /* reset iterator */ | |
3061 | dumper->active = false; | |
3062 | } | |
3063 | rcu_read_unlock(); | |
3064 | } | |
3065 | ||
3066 | /** | |
533827c9 | 3067 | * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version) |
e2ae715d KS |
3068 | * @dumper: registered kmsg dumper |
3069 | * @syslog: include the "<4>" prefixes | |
3070 | * @line: buffer to copy the line to | |
3071 | * @size: maximum size of the buffer | |
3072 | * @len: length of line placed into buffer | |
3073 | * | |
3074 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
3075 | * record, and copy one record into the provided buffer. | |
3076 | * | |
3077 | * Consecutive calls will return the next available record moving | |
3078 | * towards the end of the buffer with the youngest messages. | |
3079 | * | |
3080 | * A return value of FALSE indicates that there are no more records to | |
3081 | * read. | |
533827c9 AV |
3082 | * |
3083 | * The function is similar to kmsg_dump_get_line(), but grabs no locks. | |
e2ae715d | 3084 | */ |
533827c9 AV |
3085 | bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog, |
3086 | char *line, size_t size, size_t *len) | |
e2ae715d | 3087 | { |
62e32ac3 | 3088 | struct printk_log *msg; |
e2ae715d KS |
3089 | size_t l = 0; |
3090 | bool ret = false; | |
3091 | ||
3092 | if (!dumper->active) | |
3093 | goto out; | |
7ff9554b | 3094 | |
e2ae715d KS |
3095 | if (dumper->cur_seq < log_first_seq) { |
3096 | /* messages are gone, move to first available one */ | |
3097 | dumper->cur_seq = log_first_seq; | |
3098 | dumper->cur_idx = log_first_idx; | |
3099 | } | |
456b565c | 3100 | |
e2ae715d | 3101 | /* last entry */ |
533827c9 | 3102 | if (dumper->cur_seq >= log_next_seq) |
e2ae715d | 3103 | goto out; |
456b565c | 3104 | |
e2ae715d | 3105 | msg = log_from_idx(dumper->cur_idx); |
5aa068ea | 3106 | l = msg_print_text(msg, syslog, line, size); |
e2ae715d KS |
3107 | |
3108 | dumper->cur_idx = log_next(dumper->cur_idx); | |
3109 | dumper->cur_seq++; | |
3110 | ret = true; | |
e2ae715d KS |
3111 | out: |
3112 | if (len) | |
3113 | *len = l; | |
3114 | return ret; | |
3115 | } | |
533827c9 AV |
3116 | |
3117 | /** | |
3118 | * kmsg_dump_get_line - retrieve one kmsg log line | |
3119 | * @dumper: registered kmsg dumper | |
3120 | * @syslog: include the "<4>" prefixes | |
3121 | * @line: buffer to copy the line to | |
3122 | * @size: maximum size of the buffer | |
3123 | * @len: length of line placed into buffer | |
3124 | * | |
3125 | * Start at the beginning of the kmsg buffer, with the oldest kmsg | |
3126 | * record, and copy one record into the provided buffer. | |
3127 | * | |
3128 | * Consecutive calls will return the next available record moving | |
3129 | * towards the end of the buffer with the youngest messages. | |
3130 | * | |
3131 | * A return value of FALSE indicates that there are no more records to | |
3132 | * read. | |
3133 | */ | |
3134 | bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, | |
3135 | char *line, size_t size, size_t *len) | |
3136 | { | |
3137 | unsigned long flags; | |
3138 | bool ret; | |
3139 | ||
de6fcbdb | 3140 | logbuf_lock_irqsave(flags); |
533827c9 | 3141 | ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len); |
de6fcbdb | 3142 | logbuf_unlock_irqrestore(flags); |
533827c9 AV |
3143 | |
3144 | return ret; | |
3145 | } | |
e2ae715d KS |
3146 | EXPORT_SYMBOL_GPL(kmsg_dump_get_line); |
3147 | ||
3148 | /** | |
3149 | * kmsg_dump_get_buffer - copy kmsg log lines | |
3150 | * @dumper: registered kmsg dumper | |
3151 | * @syslog: include the "<4>" prefixes | |
4f0f4af5 | 3152 | * @buf: buffer to copy the line to |
e2ae715d KS |
3153 | * @size: maximum size of the buffer |
3154 | * @len: length of line placed into buffer | |
3155 | * | |
3156 | * Start at the end of the kmsg buffer and fill the provided buffer | |
3157 | * with as many of the the *youngest* kmsg records that fit into it. | |
3158 | * If the buffer is large enough, all available kmsg records will be | |
3159 | * copied with a single call. | |
3160 | * | |
3161 | * Consecutive calls will fill the buffer with the next block of | |
3162 | * available older records, not including the earlier retrieved ones. | |
3163 | * | |
3164 | * A return value of FALSE indicates that there are no more records to | |
3165 | * read. | |
3166 | */ | |
3167 | bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, | |
3168 | char *buf, size_t size, size_t *len) | |
3169 | { | |
3170 | unsigned long flags; | |
3171 | u64 seq; | |
3172 | u32 idx; | |
3173 | u64 next_seq; | |
3174 | u32 next_idx; | |
3175 | size_t l = 0; | |
3176 | bool ret = false; | |
3177 | ||
3178 | if (!dumper->active) | |
3179 | goto out; | |
3180 | ||
de6fcbdb | 3181 | logbuf_lock_irqsave(flags); |
e2ae715d KS |
3182 | if (dumper->cur_seq < log_first_seq) { |
3183 | /* messages are gone, move to first available one */ | |
3184 | dumper->cur_seq = log_first_seq; | |
3185 | dumper->cur_idx = log_first_idx; | |
3186 | } | |
3187 | ||
3188 | /* last entry */ | |
3189 | if (dumper->cur_seq >= dumper->next_seq) { | |
de6fcbdb | 3190 | logbuf_unlock_irqrestore(flags); |
e2ae715d KS |
3191 | goto out; |
3192 | } | |
3193 | ||
3194 | /* calculate length of entire buffer */ | |
3195 | seq = dumper->cur_seq; | |
3196 | idx = dumper->cur_idx; | |
3197 | while (seq < dumper->next_seq) { | |
62e32ac3 | 3198 | struct printk_log *msg = log_from_idx(idx); |
e2ae715d | 3199 | |
5aa068ea | 3200 | l += msg_print_text(msg, true, NULL, 0); |
e2ae715d KS |
3201 | idx = log_next(idx); |
3202 | seq++; | |
3203 | } | |
3204 | ||
3205 | /* move first record forward until length fits into the buffer */ | |
3206 | seq = dumper->cur_seq; | |
3207 | idx = dumper->cur_idx; | |
3208 | while (l > size && seq < dumper->next_seq) { | |
62e32ac3 | 3209 | struct printk_log *msg = log_from_idx(idx); |
456b565c | 3210 | |
5aa068ea | 3211 | l -= msg_print_text(msg, true, NULL, 0); |
e2ae715d KS |
3212 | idx = log_next(idx); |
3213 | seq++; | |
456b565c | 3214 | } |
e2ae715d KS |
3215 | |
3216 | /* last message in next interation */ | |
3217 | next_seq = seq; | |
3218 | next_idx = idx; | |
3219 | ||
3220 | l = 0; | |
3221 | while (seq < dumper->next_seq) { | |
62e32ac3 | 3222 | struct printk_log *msg = log_from_idx(idx); |
e2ae715d | 3223 | |
5aa068ea | 3224 | l += msg_print_text(msg, syslog, buf + l, size - l); |
e2ae715d KS |
3225 | idx = log_next(idx); |
3226 | seq++; | |
3227 | } | |
3228 | ||
3229 | dumper->next_seq = next_seq; | |
3230 | dumper->next_idx = next_idx; | |
3231 | ret = true; | |
de6fcbdb | 3232 | logbuf_unlock_irqrestore(flags); |
e2ae715d KS |
3233 | out: |
3234 | if (len) | |
3235 | *len = l; | |
3236 | return ret; | |
3237 | } | |
3238 | EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); | |
456b565c | 3239 | |
533827c9 AV |
3240 | /** |
3241 | * kmsg_dump_rewind_nolock - reset the interator (unlocked version) | |
3242 | * @dumper: registered kmsg dumper | |
3243 | * | |
3244 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
3245 | * kmsg_dump_get_buffer() can be called again and used multiple | |
3246 | * times within the same dumper.dump() callback. | |
3247 | * | |
3248 | * The function is similar to kmsg_dump_rewind(), but grabs no locks. | |
3249 | */ | |
3250 | void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper) | |
3251 | { | |
3252 | dumper->cur_seq = clear_seq; | |
3253 | dumper->cur_idx = clear_idx; | |
3254 | dumper->next_seq = log_next_seq; | |
3255 | dumper->next_idx = log_next_idx; | |
3256 | } | |
3257 | ||
e2ae715d KS |
3258 | /** |
3259 | * kmsg_dump_rewind - reset the interator | |
3260 | * @dumper: registered kmsg dumper | |
3261 | * | |
3262 | * Reset the dumper's iterator so that kmsg_dump_get_line() and | |
3263 | * kmsg_dump_get_buffer() can be called again and used multiple | |
3264 | * times within the same dumper.dump() callback. | |
3265 | */ | |
3266 | void kmsg_dump_rewind(struct kmsg_dumper *dumper) | |
3267 | { | |
3268 | unsigned long flags; | |
3269 | ||
de6fcbdb | 3270 | logbuf_lock_irqsave(flags); |
533827c9 | 3271 | kmsg_dump_rewind_nolock(dumper); |
de6fcbdb | 3272 | logbuf_unlock_irqrestore(flags); |
456b565c | 3273 | } |
e2ae715d | 3274 | EXPORT_SYMBOL_GPL(kmsg_dump_rewind); |
196779b9 | 3275 | |
7ef3d2fd | 3276 | #endif |