| 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 | |