/* $NetBSD: subr_log.c,v 1.50 2008/04/28 20:24:04 martin Exp $ */ /*- * Copyright (c) 2007, 2008 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Andrew Doran. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 1982, 1986, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)subr_log.c 8.3 (Berkeley) 2/14/95 */ /* * Error log buffer for kernel printf's. */ #include __KERNEL_RCSID(0, "$NetBSD: subr_log.c,v 1.50 2008/04/28 20:24:04 martin Exp $"); #include #include #include #include #include #include #include #include #include #include #include #include #include static void logsoftintr(void *); static bool log_async; static struct selinfo log_selp; /* process waiting on select call */ static pid_t log_pgid; /* process/group for async I/O */ static kcondvar_t log_cv; static void *log_sih; kmutex_t log_lock; int log_open; /* also used in log() */ int msgbufmapped; /* is the message buffer mapped */ int msgbufenabled; /* is logging to the buffer enabled */ struct kern_msgbuf *msgbufp; /* the mapped buffer, itself. */ void initmsgbuf(void *bf, size_t bufsize) { struct kern_msgbuf *mbp; long new_bufs; /* Sanity-check the given size. */ if (bufsize < sizeof(struct kern_msgbuf)) return; mbp = msgbufp = (struct kern_msgbuf *)bf; new_bufs = bufsize - offsetof(struct kern_msgbuf, msg_bufc); if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) || (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) || (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) { /* * If the buffer magic number is wrong, has changed * size (which shouldn't happen often), or is * internally inconsistent, initialize it. */ memset(bf, 0, bufsize); mbp->msg_magic = MSG_MAGIC; mbp->msg_bufs = new_bufs; } /* mark it as ready for use. */ msgbufmapped = msgbufenabled = 1; } void loginit(void) { mutex_init(&log_lock, MUTEX_DEFAULT, IPL_VM); selinit(&log_selp); cv_init(&log_cv, "klog"); log_sih = softint_establish(SOFTINT_CLOCK | SOFTINT_MPSAFE, logsoftintr, NULL); } /*ARGSUSED*/ static int logopen(dev_t dev, int flags, int mode, struct lwp *l) { struct kern_msgbuf *mbp = msgbufp; int error = 0; mutex_spin_enter(&log_lock); if (log_open) { error = EBUSY; } else { log_open = 1; log_pgid = l->l_proc->p_pid; /* signal process only */ /* * The message buffer is initialized during system * configuration. If it's been clobbered, note that * and return an error. (This allows a user to read * the buffer via /dev/kmem, and try to figure out * what clobbered it. */ if (mbp->msg_magic != MSG_MAGIC) { msgbufenabled = 0; error = ENXIO; } } mutex_spin_exit(&log_lock); return error; } /*ARGSUSED*/ static int logclose(dev_t dev, int flag, int mode, struct lwp *l) { mutex_spin_enter(&log_lock); log_pgid = 0; log_open = 0; log_async = 0; mutex_spin_exit(&log_lock); return 0; } /*ARGSUSED*/ static int logread(dev_t dev, struct uio *uio, int flag) { struct kern_msgbuf *mbp = msgbufp; long l; int error = 0; mutex_spin_enter(&log_lock); while (mbp->msg_bufr == mbp->msg_bufx) { if (flag & IO_NDELAY) { mutex_spin_exit(&log_lock); return EWOULDBLOCK; } error = cv_wait_sig(&log_cv, &log_lock); if (error) { mutex_spin_exit(&log_lock); return error; } } while (uio->uio_resid > 0) { l = mbp->msg_bufx - mbp->msg_bufr; if (l < 0) l = mbp->msg_bufs - mbp->msg_bufr; l = min(l, uio->uio_resid); if (l == 0) break; mutex_spin_exit(&log_lock); error = uiomove(&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio); mutex_spin_enter(&log_lock); if (error) break; mbp->msg_bufr += l; if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs) mbp->msg_bufr = 0; } mutex_spin_exit(&log_lock); return error; } /*ARGSUSED*/ static int logpoll(dev_t dev, int events, struct lwp *l) { int revents = 0; if (events & (POLLIN | POLLRDNORM)) { mutex_spin_enter(&log_lock); if (msgbufp->msg_bufr != msgbufp->msg_bufx) revents |= events & (POLLIN | POLLRDNORM); else selrecord(l, &log_selp); mutex_spin_exit(&log_lock); } return revents; } static void filt_logrdetach(struct knote *kn) { mutex_spin_enter(&log_lock); SLIST_REMOVE(&log_selp.sel_klist, kn, knote, kn_selnext); mutex_spin_exit(&log_lock); } static int filt_logread(struct knote *kn, long hint) { int rv; if ((hint & NOTE_SUBMIT) == 0) mutex_spin_enter(&log_lock); if (msgbufp->msg_bufr == msgbufp->msg_bufx) { rv = 0; } else if (msgbufp->msg_bufr < msgbufp->msg_bufx) { kn->kn_data = msgbufp->msg_bufx - msgbufp->msg_bufr; rv = 1; } else { kn->kn_data = (msgbufp->msg_bufs - msgbufp->msg_bufr) + msgbufp->msg_bufx; rv = 1; } if ((hint & NOTE_SUBMIT) == 0) mutex_spin_exit(&log_lock); return rv; } static const struct filterops logread_filtops = { 1, NULL, filt_logrdetach, filt_logread }; static int logkqfilter(dev_t dev, struct knote *kn) { struct klist *klist; switch (kn->kn_filter) { case EVFILT_READ: klist = &log_selp.sel_klist; kn->kn_fop = &logread_filtops; break; default: return (EINVAL); } mutex_spin_enter(&log_lock); kn->kn_hook = NULL; SLIST_INSERT_HEAD(klist, kn, kn_selnext); mutex_spin_exit(&log_lock); return (0); } void logwakeup(void) { if (!cold && log_open) { mutex_spin_enter(&log_lock); selnotify(&log_selp, 0, NOTE_SUBMIT); if (log_async) softint_schedule(log_sih); cv_broadcast(&log_cv); mutex_spin_exit(&log_lock); } } static void logsoftintr(void *cookie) { pid_t pid; if ((pid = log_pgid) != 0) fownsignal(pid, SIGIO, 0, 0, NULL); } /*ARGSUSED*/ static int logioctl(dev_t dev, u_long com, void *data, int flag, struct lwp *lwp) { long l; switch (com) { /* return number of characters immediately available */ case FIONREAD: mutex_spin_enter(&log_lock); l = msgbufp->msg_bufx - msgbufp->msg_bufr; if (l < 0) l += msgbufp->msg_bufs; mutex_spin_exit(&log_lock); *(int *)data = l; break; case FIONBIO: break; case FIOASYNC: /* No locking needed, 'thread private'. */ log_async = (*((int *)data) != 0); break; case TIOCSPGRP: case FIOSETOWN: return fsetown(&log_pgid, com, data); case TIOCGPGRP: case FIOGETOWN: return fgetown(log_pgid, com, data); default: return (EPASSTHROUGH); } return (0); } void logputchar(int c) { struct kern_msgbuf *mbp; if (!cold) mutex_spin_enter(&log_lock); if (msgbufenabled) { mbp = msgbufp; if (mbp->msg_magic != MSG_MAGIC) { /* * Arguably should panic or somehow notify the * user... but how? Panic may be too drastic, * and would obliterate the message being kicked * out (maybe a panic itself), and printf * would invoke us recursively. Silently punt * for now. If syslog is running, it should * notice. */ msgbufenabled = 0; } else { mbp->msg_bufc[mbp->msg_bufx++] = c; if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs) mbp->msg_bufx = 0; /* If the buffer is full, keep the most recent data. */ if (mbp->msg_bufr == mbp->msg_bufx) { if (++mbp->msg_bufr >= mbp->msg_bufs) mbp->msg_bufr = 0; } } } if (!cold) mutex_spin_exit(&log_lock); } const struct cdevsw log_cdevsw = { logopen, logclose, logread, nowrite, logioctl, nostop, notty, logpoll, nommap, logkqfilter, D_OTHER | D_MPSAFE };