1 | /* $NetBSD: subr_log.c,v 1.55 2015/05/20 11:18:36 pooka Exp $ */ |
2 | |
3 | /*- |
4 | * Copyright (c) 2007, 2008 The NetBSD Foundation, Inc. |
5 | * All rights reserved. |
6 | * |
7 | * This code is derived from software contributed to The NetBSD Foundation |
8 | * by Andrew Doran. |
9 | * |
10 | * Redistribution and use in source and binary forms, with or without |
11 | * modification, are permitted provided that the following conditions |
12 | * are met: |
13 | * 1. Redistributions of source code must retain the above copyright |
14 | * notice, this list of conditions and the following disclaimer. |
15 | * 2. Redistributions in binary form must reproduce the above copyright |
16 | * notice, this list of conditions and the following disclaimer in the |
17 | * documentation and/or other materials provided with the distribution. |
18 | * |
19 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
20 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
21 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
23 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
24 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
25 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
26 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
27 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
28 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
29 | * POSSIBILITY OF SUCH DAMAGE. |
30 | */ |
31 | |
32 | /* |
33 | * Copyright (c) 1982, 1986, 1993 |
34 | * The Regents of the University of California. All rights reserved. |
35 | * |
36 | * Redistribution and use in source and binary forms, with or without |
37 | * modification, are permitted provided that the following conditions |
38 | * are met: |
39 | * 1. Redistributions of source code must retain the above copyright |
40 | * notice, this list of conditions and the following disclaimer. |
41 | * 2. Redistributions in binary form must reproduce the above copyright |
42 | * notice, this list of conditions and the following disclaimer in the |
43 | * documentation and/or other materials provided with the distribution. |
44 | * 3. Neither the name of the University nor the names of its contributors |
45 | * may be used to endorse or promote products derived from this software |
46 | * without specific prior written permission. |
47 | * |
48 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
49 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
50 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
51 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
52 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
53 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
54 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
55 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
56 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
57 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
58 | * SUCH DAMAGE. |
59 | * |
60 | * @(#)subr_log.c 8.3 (Berkeley) 2/14/95 |
61 | */ |
62 | |
63 | /* |
64 | * Error log buffer for kernel printf's. |
65 | */ |
66 | |
67 | #include <sys/cdefs.h> |
68 | __KERNEL_RCSID(0, "$NetBSD: subr_log.c,v 1.55 2015/05/20 11:18:36 pooka Exp $" ); |
69 | |
70 | #include <sys/param.h> |
71 | #include <sys/systm.h> |
72 | #include <sys/kernel.h> |
73 | #include <sys/proc.h> |
74 | #include <sys/vnode.h> |
75 | #include <sys/ioctl.h> |
76 | #include <sys/msgbuf.h> |
77 | #include <sys/file.h> |
78 | #include <sys/syslog.h> |
79 | #include <sys/conf.h> |
80 | #include <sys/select.h> |
81 | #include <sys/poll.h> |
82 | #include <sys/intr.h> |
83 | #include <sys/sysctl.h> |
84 | #include <sys/ktrace.h> |
85 | |
86 | static int sysctl_msgbuf(SYSCTLFN_PROTO); |
87 | |
88 | static void logsoftintr(void *); |
89 | |
90 | static bool log_async; |
91 | static struct selinfo log_selp; /* process waiting on select call */ |
92 | static pid_t log_pgid; /* process/group for async I/O */ |
93 | static kcondvar_t log_cv; |
94 | static void *log_sih; |
95 | |
96 | kmutex_t log_lock; |
97 | int log_open; /* also used in log() */ |
98 | int msgbufmapped; /* is the message buffer mapped */ |
99 | int msgbufenabled; /* is logging to the buffer enabled */ |
100 | struct kern_msgbuf *msgbufp; /* the mapped buffer, itself. */ |
101 | |
102 | void |
103 | initmsgbuf(void *bf, size_t bufsize) |
104 | { |
105 | struct kern_msgbuf *mbp; |
106 | long new_bufs; |
107 | |
108 | /* Sanity-check the given size. */ |
109 | if (bufsize < sizeof(struct kern_msgbuf)) |
110 | return; |
111 | |
112 | mbp = msgbufp = (struct kern_msgbuf *)bf; |
113 | |
114 | new_bufs = bufsize - offsetof(struct kern_msgbuf, msg_bufc); |
115 | if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) || |
116 | (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) || |
117 | (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) { |
118 | /* |
119 | * If the buffer magic number is wrong, has changed |
120 | * size (which shouldn't happen often), or is |
121 | * internally inconsistent, initialize it. |
122 | */ |
123 | |
124 | memset(bf, 0, bufsize); |
125 | mbp->msg_magic = MSG_MAGIC; |
126 | mbp->msg_bufs = new_bufs; |
127 | } |
128 | |
129 | /* mark it as ready for use. */ |
130 | msgbufmapped = msgbufenabled = 1; |
131 | } |
132 | |
133 | void |
134 | loginit(void) |
135 | { |
136 | |
137 | mutex_init(&log_lock, MUTEX_DEFAULT, IPL_VM); |
138 | selinit(&log_selp); |
139 | cv_init(&log_cv, "klog" ); |
140 | log_sih = softint_establish(SOFTINT_CLOCK | SOFTINT_MPSAFE, |
141 | logsoftintr, NULL); |
142 | |
143 | sysctl_createv(NULL, 0, NULL, NULL, |
144 | CTLFLAG_PERMANENT, |
145 | CTLTYPE_INT, "msgbufsize" , |
146 | SYSCTL_DESCR("Size of the kernel message buffer" ), |
147 | sysctl_msgbuf, 0, NULL, 0, |
148 | CTL_KERN, KERN_MSGBUFSIZE, CTL_EOL); |
149 | sysctl_createv(NULL, 0, NULL, NULL, |
150 | CTLFLAG_PERMANENT, |
151 | CTLTYPE_INT, "msgbuf" , |
152 | SYSCTL_DESCR("Kernel message buffer" ), |
153 | sysctl_msgbuf, 0, NULL, 0, |
154 | CTL_KERN, KERN_MSGBUF, CTL_EOL); |
155 | } |
156 | |
157 | /*ARGSUSED*/ |
158 | static int |
159 | logopen(dev_t dev, int flags, int mode, struct lwp *l) |
160 | { |
161 | struct kern_msgbuf *mbp = msgbufp; |
162 | int error = 0; |
163 | |
164 | mutex_spin_enter(&log_lock); |
165 | if (log_open) { |
166 | error = EBUSY; |
167 | } else { |
168 | log_open = 1; |
169 | log_pgid = l->l_proc->p_pid; /* signal process only */ |
170 | /* |
171 | * The message buffer is initialized during system |
172 | * configuration. If it's been clobbered, note that |
173 | * and return an error. (This allows a user to read |
174 | * the buffer via /dev/kmem, and try to figure out |
175 | * what clobbered it. |
176 | */ |
177 | if (mbp->msg_magic != MSG_MAGIC) { |
178 | msgbufenabled = 0; |
179 | error = ENXIO; |
180 | } |
181 | } |
182 | mutex_spin_exit(&log_lock); |
183 | |
184 | return error; |
185 | } |
186 | |
187 | /*ARGSUSED*/ |
188 | static int |
189 | logclose(dev_t dev, int flag, int mode, struct lwp *l) |
190 | { |
191 | |
192 | mutex_spin_enter(&log_lock); |
193 | log_pgid = 0; |
194 | log_open = 0; |
195 | log_async = 0; |
196 | mutex_spin_exit(&log_lock); |
197 | |
198 | return 0; |
199 | } |
200 | |
201 | /*ARGSUSED*/ |
202 | static int |
203 | logread(dev_t dev, struct uio *uio, int flag) |
204 | { |
205 | struct kern_msgbuf *mbp = msgbufp; |
206 | long l; |
207 | int error = 0; |
208 | |
209 | mutex_spin_enter(&log_lock); |
210 | while (mbp->msg_bufr == mbp->msg_bufx) { |
211 | if (flag & IO_NDELAY) { |
212 | mutex_spin_exit(&log_lock); |
213 | return EWOULDBLOCK; |
214 | } |
215 | error = cv_wait_sig(&log_cv, &log_lock); |
216 | if (error) { |
217 | mutex_spin_exit(&log_lock); |
218 | return error; |
219 | } |
220 | } |
221 | while (uio->uio_resid > 0) { |
222 | l = mbp->msg_bufx - mbp->msg_bufr; |
223 | if (l < 0) |
224 | l = mbp->msg_bufs - mbp->msg_bufr; |
225 | l = min(l, uio->uio_resid); |
226 | if (l == 0) |
227 | break; |
228 | mutex_spin_exit(&log_lock); |
229 | error = uiomove(&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio); |
230 | mutex_spin_enter(&log_lock); |
231 | if (error) |
232 | break; |
233 | mbp->msg_bufr += l; |
234 | if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs) |
235 | mbp->msg_bufr = 0; |
236 | } |
237 | mutex_spin_exit(&log_lock); |
238 | |
239 | return error; |
240 | } |
241 | |
242 | /*ARGSUSED*/ |
243 | static int |
244 | logpoll(dev_t dev, int events, struct lwp *l) |
245 | { |
246 | int revents = 0; |
247 | |
248 | if (events & (POLLIN | POLLRDNORM)) { |
249 | mutex_spin_enter(&log_lock); |
250 | if (msgbufp->msg_bufr != msgbufp->msg_bufx) |
251 | revents |= events & (POLLIN | POLLRDNORM); |
252 | else |
253 | selrecord(l, &log_selp); |
254 | mutex_spin_exit(&log_lock); |
255 | } |
256 | |
257 | return revents; |
258 | } |
259 | |
260 | static void |
261 | filt_logrdetach(struct knote *kn) |
262 | { |
263 | |
264 | mutex_spin_enter(&log_lock); |
265 | SLIST_REMOVE(&log_selp.sel_klist, kn, knote, kn_selnext); |
266 | mutex_spin_exit(&log_lock); |
267 | } |
268 | |
269 | static int |
270 | filt_logread(struct knote *kn, long hint) |
271 | { |
272 | int rv; |
273 | |
274 | if ((hint & NOTE_SUBMIT) == 0) |
275 | mutex_spin_enter(&log_lock); |
276 | if (msgbufp->msg_bufr == msgbufp->msg_bufx) { |
277 | rv = 0; |
278 | } else if (msgbufp->msg_bufr < msgbufp->msg_bufx) { |
279 | kn->kn_data = msgbufp->msg_bufx - msgbufp->msg_bufr; |
280 | rv = 1; |
281 | } else { |
282 | kn->kn_data = (msgbufp->msg_bufs - msgbufp->msg_bufr) + |
283 | msgbufp->msg_bufx; |
284 | rv = 1; |
285 | } |
286 | if ((hint & NOTE_SUBMIT) == 0) |
287 | mutex_spin_exit(&log_lock); |
288 | |
289 | return rv; |
290 | } |
291 | |
292 | static const struct filterops logread_filtops = |
293 | { 1, NULL, filt_logrdetach, filt_logread }; |
294 | |
295 | static int |
296 | logkqfilter(dev_t dev, struct knote *kn) |
297 | { |
298 | struct klist *klist; |
299 | |
300 | switch (kn->kn_filter) { |
301 | case EVFILT_READ: |
302 | klist = &log_selp.sel_klist; |
303 | kn->kn_fop = &logread_filtops; |
304 | break; |
305 | |
306 | default: |
307 | return (EINVAL); |
308 | } |
309 | |
310 | mutex_spin_enter(&log_lock); |
311 | kn->kn_hook = NULL; |
312 | SLIST_INSERT_HEAD(klist, kn, kn_selnext); |
313 | mutex_spin_exit(&log_lock); |
314 | |
315 | return (0); |
316 | } |
317 | |
318 | void |
319 | logwakeup(void) |
320 | { |
321 | |
322 | if (!cold && log_open) { |
323 | mutex_spin_enter(&log_lock); |
324 | selnotify(&log_selp, 0, NOTE_SUBMIT); |
325 | if (log_async) |
326 | softint_schedule(log_sih); |
327 | cv_broadcast(&log_cv); |
328 | mutex_spin_exit(&log_lock); |
329 | } |
330 | } |
331 | |
332 | static void |
333 | logsoftintr(void *cookie) |
334 | { |
335 | pid_t pid; |
336 | |
337 | if ((pid = log_pgid) != 0) |
338 | fownsignal(pid, SIGIO, 0, 0, NULL); |
339 | } |
340 | |
341 | /*ARGSUSED*/ |
342 | static int |
343 | logioctl(dev_t dev, u_long com, void *data, int flag, struct lwp *lwp) |
344 | { |
345 | long l; |
346 | |
347 | switch (com) { |
348 | |
349 | /* return number of characters immediately available */ |
350 | case FIONREAD: |
351 | mutex_spin_enter(&log_lock); |
352 | l = msgbufp->msg_bufx - msgbufp->msg_bufr; |
353 | if (l < 0) |
354 | l += msgbufp->msg_bufs; |
355 | mutex_spin_exit(&log_lock); |
356 | *(int *)data = l; |
357 | break; |
358 | |
359 | case FIONBIO: |
360 | break; |
361 | |
362 | case FIOASYNC: |
363 | /* No locking needed, 'thread private'. */ |
364 | log_async = (*((int *)data) != 0); |
365 | break; |
366 | |
367 | case TIOCSPGRP: |
368 | case FIOSETOWN: |
369 | return fsetown(&log_pgid, com, data); |
370 | |
371 | case TIOCGPGRP: |
372 | case FIOGETOWN: |
373 | return fgetown(log_pgid, com, data); |
374 | |
375 | default: |
376 | return (EPASSTHROUGH); |
377 | } |
378 | return (0); |
379 | } |
380 | |
381 | void |
382 | logputchar(int c) |
383 | { |
384 | struct kern_msgbuf *mbp; |
385 | |
386 | if (!cold) |
387 | mutex_spin_enter(&log_lock); |
388 | if (msgbufenabled) { |
389 | mbp = msgbufp; |
390 | if (mbp->msg_magic != MSG_MAGIC) { |
391 | /* |
392 | * Arguably should panic or somehow notify the |
393 | * user... but how? Panic may be too drastic, |
394 | * and would obliterate the message being kicked |
395 | * out (maybe a panic itself), and printf |
396 | * would invoke us recursively. Silently punt |
397 | * for now. If syslog is running, it should |
398 | * notice. |
399 | */ |
400 | msgbufenabled = 0; |
401 | } else { |
402 | mbp->msg_bufc[mbp->msg_bufx++] = c; |
403 | if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs) |
404 | mbp->msg_bufx = 0; |
405 | /* If the buffer is full, keep the most recent data. */ |
406 | if (mbp->msg_bufr == mbp->msg_bufx) { |
407 | char c0; |
408 | int i; |
409 | |
410 | /* |
411 | * Move forward read pointer to the next line |
412 | * in the buffer. Note that the buffer is |
413 | * a ring buffer so we should reset msg_bufr |
414 | * to 0 when msg_bufr exceeds msg_bufs. |
415 | * |
416 | * To prevent to loop forever, give up if we |
417 | * cannot find a newline in mbp->msg_bufs |
418 | * characters (the max size of the buffer). |
419 | */ |
420 | for (i = 0; i < mbp->msg_bufs; i++) { |
421 | c0 = mbp->msg_bufc[mbp->msg_bufr]; |
422 | if (++mbp->msg_bufr >= mbp->msg_bufs) |
423 | mbp->msg_bufr = 0; |
424 | if (c0 == '\n') |
425 | break; |
426 | } |
427 | } |
428 | } |
429 | } |
430 | if (!cold) |
431 | mutex_spin_exit(&log_lock); |
432 | } |
433 | |
434 | /* |
435 | * sysctl helper routine for kern.msgbufsize and kern.msgbuf. For the |
436 | * former it merely checks the message buffer is set up. For the latter, |
437 | * it also copies out the data if necessary. |
438 | */ |
439 | static int |
440 | sysctl_msgbuf(SYSCTLFN_ARGS) |
441 | { |
442 | char *where = oldp; |
443 | size_t len, maxlen; |
444 | long beg, end; |
445 | extern kmutex_t log_lock; |
446 | int error; |
447 | |
448 | if (!msgbufenabled || msgbufp->msg_magic != MSG_MAGIC) { |
449 | msgbufenabled = 0; |
450 | return (ENXIO); |
451 | } |
452 | |
453 | switch (rnode->sysctl_num) { |
454 | case KERN_MSGBUFSIZE: { |
455 | struct sysctlnode node = *rnode; |
456 | int msg_bufs = (int)msgbufp->msg_bufs; |
457 | node.sysctl_data = &msg_bufs; |
458 | return (sysctl_lookup(SYSCTLFN_CALL(&node))); |
459 | } |
460 | case KERN_MSGBUF: |
461 | break; |
462 | default: |
463 | return (EOPNOTSUPP); |
464 | } |
465 | |
466 | if (newp != NULL) |
467 | return (EPERM); |
468 | |
469 | if (oldp == NULL) { |
470 | /* always return full buffer size */ |
471 | *oldlenp = msgbufp->msg_bufs; |
472 | return (0); |
473 | } |
474 | |
475 | sysctl_unlock(); |
476 | |
477 | /* |
478 | * First, copy from the write pointer to the end of |
479 | * message buffer. |
480 | */ |
481 | error = 0; |
482 | mutex_spin_enter(&log_lock); |
483 | maxlen = MIN(msgbufp->msg_bufs, *oldlenp); |
484 | beg = msgbufp->msg_bufx; |
485 | end = msgbufp->msg_bufs; |
486 | mutex_spin_exit(&log_lock); |
487 | |
488 | while (maxlen > 0) { |
489 | len = MIN(end - beg, maxlen); |
490 | if (len == 0) |
491 | break; |
492 | /* XXX unlocked, but hardly matters. */ |
493 | error = copyout(&msgbufp->msg_bufc[beg], where, len); |
494 | ktrmibio(-1, UIO_READ, where, len, error); |
495 | if (error) |
496 | break; |
497 | where += len; |
498 | maxlen -= len; |
499 | |
500 | /* |
501 | * ... then, copy from the beginning of message buffer to |
502 | * the write pointer. |
503 | */ |
504 | beg = 0; |
505 | end = msgbufp->msg_bufx; |
506 | } |
507 | |
508 | sysctl_relock(); |
509 | return (error); |
510 | } |
511 | |
512 | const struct cdevsw log_cdevsw = { |
513 | .d_open = logopen, |
514 | .d_close = logclose, |
515 | .d_read = logread, |
516 | .d_write = nowrite, |
517 | .d_ioctl = logioctl, |
518 | .d_stop = nostop, |
519 | .d_tty = notty, |
520 | .d_poll = logpoll, |
521 | .d_mmap = nommap, |
522 | .d_kqfilter = logkqfilter, |
523 | .d_discard = nodiscard, |
524 | .d_flag = D_OTHER | D_MPSAFE |
525 | }; |
526 | |