diff --git a/sbin/dmesg/dmesg.8 b/sbin/dmesg/dmesg.8 index 13101baf7e78..a924549264cd 100644 --- a/sbin/dmesg/dmesg.8 +++ b/sbin/dmesg/dmesg.8 @@ -1,100 +1,103 @@ .\" Copyright (c) 1980, 1991, 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. .\" .\" @(#)dmesg.8 8.1 (Berkeley) 6/5/93 .\" $FreeBSD$ .\" .Dd May 6, 2022 .Dt DMESG 8 .Os .Sh NAME .Nm dmesg .Nd "display the system message buffer" .Sh SYNOPSIS .Nm .Op Fl ac .Op Fl M Ar core Op Fl N Ar system .Sh DESCRIPTION The .Nm utility displays the contents of the system message buffer. If the .Fl M option is not specified, the buffer is read from the currently running kernel via the .Xr sysctl 3 interface. Otherwise, the buffer is read from the specified core file, using the name list from the specified kernel image (or from the default image). .Pp The options are as follows: .Bl -tag -width indent .It Fl a Show all data in the message buffer. This includes any syslog records and .Pa /dev/console output. .It Fl c Clear the kernel buffer after printing. .It Fl M Extract values associated with the name list from the specified core. .It Fl N If .Fl M is also specified, extract the name list from the specified system instead of the default, which is the kernel image the system has booted from. .El .Sh SYSCTL VARIABLES The following .Xr sysctl 8 variables can be used to control the behavior of the kernel's placing data into the message buffer: The default value is shown next to each variable. .Bl -tag -width indent .It kern.msgbuf_show_timestamp : No 0 -If set to 1, then a timestamp will be added to most lines in the message buffer. +If set to 0, no timetamps are added. +If set to 1, then a 1-second granularity timestamp will be added to most lines +in the message buffer. +If set to 2, then a microsecond granularity timestamp will be added. This may also be set as a boot .Xr loader 8 tunable. .El .Sh FILES .Bl -tag -width ".Pa /var/run/dmesg.boot" -compact .It Pa /var/run/dmesg.boot usually a snapshot of the buffer contents taken soon after file systems are mounted at startup time .El .Sh SEE ALSO .Xr sysctl 3 , .Xr syslogd 8 .Sh HISTORY The .Nm utility appeared in .Bx 3 . diff --git a/sys/kern/subr_msgbuf.c b/sys/kern/subr_msgbuf.c index b41e78dd886e..4664e742c5fb 100644 --- a/sys/kern/subr_msgbuf.c +++ b/sys/kern/subr_msgbuf.c @@ -1,426 +1,434 @@ /*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2003 Ian Dowse. 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. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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. * * $FreeBSD$ */ /* * Generic message buffer support routines. */ #include #include #include #include #include #include #include /* * Maximum number conversion buffer length: uintmax_t in base 2, plus <> * around the priority, and a terminating NUL. */ #define MAXPRIBUF (sizeof(intmax_t) * NBBY + 3) /* Read/write sequence numbers are modulo a multiple of the buffer size. */ #define SEQMOD(size) ((size) * 16) static u_int msgbuf_cksum(struct msgbuf *mbp); /* * Timestamps in msgbuf are useful when trying to diagnose when core dumps * or other actions occurred. */ static int msgbuf_show_timestamp = 0; SYSCTL_INT(_kern, OID_AUTO, msgbuf_show_timestamp, CTLFLAG_RWTUN, &msgbuf_show_timestamp, 0, "Show timestamp in msgbuf"); /* * Initialize a message buffer of the specified size at the specified * location. This also zeros the buffer area. */ void msgbuf_init(struct msgbuf *mbp, void *ptr, int size) { mbp->msg_ptr = ptr; mbp->msg_size = size; mbp->msg_seqmod = SEQMOD(size); mbp->msg_lastpri = -1; mbp->msg_flags = 0; msgbuf_clear(mbp); mbp->msg_magic = MSG_MAGIC; bzero(&mbp->msg_lock, sizeof(mbp->msg_lock)); mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN); } /* * Reinitialize a message buffer, retaining its previous contents if * the size and checksum are correct. If the old contents cannot be * recovered, the message buffer is cleared. */ void msgbuf_reinit(struct msgbuf *mbp, void *ptr, int size) { u_int cksum; if (mbp->msg_magic != MSG_MAGIC || mbp->msg_size != size) { msgbuf_init(mbp, ptr, size); return; } mbp->msg_seqmod = SEQMOD(size); mbp->msg_wseq = MSGBUF_SEQNORM(mbp, mbp->msg_wseq); mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq); mbp->msg_ptr = ptr; cksum = msgbuf_cksum(mbp); if (cksum != mbp->msg_cksum) { if (bootverbose) { printf("msgbuf cksum mismatch (read %x, calc %x)\n", mbp->msg_cksum, cksum); printf("Old msgbuf not recovered\n"); } msgbuf_clear(mbp); } mbp->msg_lastpri = -1; /* Assume that the old message buffer didn't end in a newline. */ mbp->msg_flags |= MSGBUF_NEEDNL; bzero(&mbp->msg_lock, sizeof(mbp->msg_lock)); mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN); } /* * Clear the message buffer. */ void msgbuf_clear(struct msgbuf *mbp) { bzero(mbp->msg_ptr, mbp->msg_size); mbp->msg_wseq = 0; mbp->msg_rseq = 0; mbp->msg_cksum = 0; mbp->msg_flags &= ~MSGBUF_WRAP; } /* * Get a count of the number of unread characters in the message buffer. */ int msgbuf_getcount(struct msgbuf *mbp) { u_int len; len = MSGBUF_SEQSUB(mbp, mbp->msg_wseq, mbp->msg_rseq); if (len > mbp->msg_size) len = mbp->msg_size; return (len); } /* * Add a character into the message buffer, and update the checksum and * sequence number. * * The caller should hold the message buffer spinlock. */ static void msgbuf_do_addchar(struct msgbuf * const mbp, const int c) { u_int pos; /* Make sure we properly wrap the sequence number. */ pos = MSGBUF_SEQ_TO_POS(mbp, mbp->msg_wseq); mbp->msg_cksum += (u_int)(u_char)c - (u_int)(u_char)mbp->msg_ptr[pos]; mbp->msg_ptr[pos] = c; mbp->msg_wseq = MSGBUF_SEQADD(mbp, mbp->msg_wseq, 1); } /* * Append a character to a message buffer. */ void msgbuf_addchar(struct msgbuf *mbp, int c) { mtx_lock_spin(&mbp->msg_lock); msgbuf_do_addchar(mbp, c); if (mbp->msg_wseq >= mbp->msg_size) mbp->msg_flags |= MSGBUF_WRAP; mtx_unlock_spin(&mbp->msg_lock); } /* * Append a NUL-terminated string with a priority to a message buffer. * Filter carriage returns if the caller requests it. * * XXX The carriage return filtering behavior is present in the * msglogchar() API, however testing has shown that we don't seem to send * carriage returns down this path. So do we still need it? */ void msgbuf_addstr(struct msgbuf *mbp, int pri, const char *str, int filter_cr) { size_t len, prefix_len; char prefix[MAXPRIBUF]; char buf[32]; int i, j, needtime; len = strlen(str); prefix_len = 0; /* If we have a zero-length string, no need to do anything. */ if (len == 0) return; mtx_lock_spin(&mbp->msg_lock); /* * If this is true, we may need to insert a new priority sequence, * so prepare the prefix. */ if (pri != -1) prefix_len = sprintf(prefix, "<%d>", pri); /* * Whenever there is a change in priority, we have to insert a * newline, and a priority prefix if the priority is not -1. Here * we detect whether there was a priority change, and whether we * did not end with a newline. If that is the case, we need to * insert a newline before this string. */ if (mbp->msg_lastpri != pri && (mbp->msg_flags & MSGBUF_NEEDNL) != 0) { msgbuf_do_addchar(mbp, '\n'); mbp->msg_flags &= ~MSGBUF_NEEDNL; } needtime = 1; for (i = 0; i < len; i++) { /* * If we just had a newline, and the priority is not -1 * (and therefore prefix_len != 0), then we need a priority * prefix for this line. */ if ((mbp->msg_flags & MSGBUF_NEEDNL) == 0 && prefix_len != 0) { int j; for (j = 0; j < prefix_len; j++) msgbuf_do_addchar(mbp, prefix[j]); } if (msgbuf_show_timestamp && needtime == 1 && (mbp->msg_flags & MSGBUF_NEEDNL) == 0) { - snprintf(buf, sizeof(buf), "[%jd] ", - (intmax_t)time_uptime); + if (msgbuf_show_timestamp == 1) { + snprintf(buf, sizeof(buf), "[%jd] ", + (intmax_t)time_uptime); + } else { + struct timeval tv; + + microuptime(&tv); + snprintf(buf, sizeof(buf), "[%jd.%06d] ", + (intmax_t)tv.tv_sec, (int)tv.tv_usec); + } for (j = 0; buf[j] != '\0'; j++) msgbuf_do_addchar(mbp, buf[j]); needtime = 0; } /* * Don't copy carriage returns if the caller requested * filtering. * * XXX This matches the behavior of msglogchar(), but is it * necessary? Testing has shown that we don't seem to get * carriage returns here. */ if ((filter_cr != 0) && (str[i] == '\r')) continue; /* * Clear this flag if we see a newline. This affects whether * we need to insert a new prefix or insert a newline later. */ if (str[i] == '\n') mbp->msg_flags &= ~MSGBUF_NEEDNL; else mbp->msg_flags |= MSGBUF_NEEDNL; msgbuf_do_addchar(mbp, str[i]); } if (mbp->msg_wseq >= mbp->msg_size) mbp->msg_flags |= MSGBUF_WRAP; /* * Set the last priority. */ mbp->msg_lastpri = pri; mtx_unlock_spin(&mbp->msg_lock); } /* * Read and mark as read a character from a message buffer. * Returns the character, or -1 if no characters are available. */ int msgbuf_getchar(struct msgbuf *mbp) { u_int len, wseq; int c; mtx_lock_spin(&mbp->msg_lock); wseq = mbp->msg_wseq; len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq); if (len == 0) { mtx_unlock_spin(&mbp->msg_lock); return (-1); } if (len > mbp->msg_size) mbp->msg_rseq = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_size); c = (u_char)mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq)]; mbp->msg_rseq = MSGBUF_SEQADD(mbp, mbp->msg_rseq, 1); mtx_unlock_spin(&mbp->msg_lock); return (c); } /* * Read and mark as read a number of characters from a message buffer. * Returns the number of characters that were placed in `buf'. */ int msgbuf_getbytes(struct msgbuf *mbp, char *buf, int buflen) { u_int len, pos, wseq; mtx_lock_spin(&mbp->msg_lock); wseq = mbp->msg_wseq; len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq); if (len == 0) { mtx_unlock_spin(&mbp->msg_lock); return (0); } if (len > mbp->msg_size) { mbp->msg_rseq = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_size); len = mbp->msg_size; } pos = MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq); len = min(len, mbp->msg_size - pos); len = min(len, (u_int)buflen); bcopy(&mbp->msg_ptr[pos], buf, len); mbp->msg_rseq = MSGBUF_SEQADD(mbp, mbp->msg_rseq, len); mtx_unlock_spin(&mbp->msg_lock); return (len); } /* * Peek at the full contents of a message buffer without marking any * data as read. `seqp' should point to an unsigned integer that * msgbuf_peekbytes() can use to retain state between calls so that * the whole message buffer can be read in multiple short reads. * To initialise this variable to the start of the message buffer, * call msgbuf_peekbytes() with a NULL `buf' parameter. * * Returns the number of characters that were placed in `buf'. */ int msgbuf_peekbytes(struct msgbuf *mbp, char *buf, int buflen, u_int *seqp) { u_int len, pos, wseq; mtx_lock_spin(&mbp->msg_lock); if (buf == NULL) { /* Just initialise *seqp. */ if (mbp->msg_flags & MSGBUF_WRAP) *seqp = MSGBUF_SEQSUB(mbp, mbp->msg_wseq, mbp->msg_size); else *seqp = 0; mtx_unlock_spin(&mbp->msg_lock); return (0); } wseq = mbp->msg_wseq; len = MSGBUF_SEQSUB(mbp, wseq, *seqp); if (len == 0) { mtx_unlock_spin(&mbp->msg_lock); return (0); } if (len > mbp->msg_size) { *seqp = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_size); len = mbp->msg_size; } pos = MSGBUF_SEQ_TO_POS(mbp, *seqp); len = min(len, mbp->msg_size - pos); len = min(len, (u_int)buflen); bcopy(&mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, *seqp)], buf, len); *seqp = MSGBUF_SEQADD(mbp, *seqp, len); mtx_unlock_spin(&mbp->msg_lock); return (len); } /* * Compute the checksum for the complete message buffer contents. */ static u_int msgbuf_cksum(struct msgbuf *mbp) { u_int i, sum; sum = 0; for (i = 0; i < mbp->msg_size; i++) sum += (u_char)mbp->msg_ptr[i]; return (sum); } /* * Copy from one message buffer to another. */ void msgbuf_copy(struct msgbuf *src, struct msgbuf *dst) { int c; while ((c = msgbuf_getchar(src)) >= 0) msgbuf_addchar(dst, c); } /* * Get a snapshot of the message buffer, without modifying its internal state * (i.e. don't mark any new characters as read). */ void msgbuf_duplicate(struct msgbuf *src, struct msgbuf *dst, char *dst_msgptr) { mtx_lock_spin(&src->msg_lock); bcopy(src, dst, sizeof(struct msgbuf)); dst->msg_ptr = dst_msgptr; bcopy(src->msg_ptr, dst->msg_ptr, src->msg_size); mtx_unlock_spin(&src->msg_lock); }