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Diffstat (limited to 'lib/libc/sys/ktrace.2')
| -rw-r--r-- | lib/libc/sys/ktrace.2 | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/lib/libc/sys/ktrace.2 b/lib/libc/sys/ktrace.2 new file mode 100644 index 0000000..598cc91 --- /dev/null +++ b/lib/libc/sys/ktrace.2 @@ -0,0 +1,196 @@ +.\" Copyright (c) 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. +.\" 4. 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. +.\" +.\" @(#)ktrace.2 8.1 (Berkeley) 6/4/93 +.\" $FreeBSD$ +.\" +.Dd June 4, 1993 +.Dt KTRACE 2 +.Os +.Sh NAME +.Nm ktrace +.Nd process tracing +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In sys/param.h +.In sys/time.h +.In sys/uio.h +.In sys/ktrace.h +.Ft int +.Fn ktrace "const char *tracefile" "int ops" "int trpoints" "int pid" +.Sh DESCRIPTION +The +.Fn ktrace +system call enables or disables tracing of one or more processes. +Users may only trace their own processes. +Only the super-user can trace setuid or setgid programs. +.Pp +The +.Fa tracefile +argument +gives the pathname of the file to be used for tracing. +The file must exist and be a regular file writable by the calling process. +All trace records are always appended to the file, +so the file must be truncated to zero length to discard +previous trace data. +If tracing points are being disabled (see KTROP_CLEAR below), +.Fa tracefile +may be NULL. +.Pp +The +.Fa ops +argument specifies the requested ktrace operation. +The defined operations are: +.Bl -column KTRFLAG_DESCENDXXX -offset indent +.It "KTROP_SET Enable trace points specified in" +.Fa trpoints . +.It "KTROP_CLEAR Disable trace points specified in +.Fa trpoints . +.It "KTROP_CLEARFILE Stop all tracing." +.It "KTRFLAG_DESCEND The tracing change should apply to the" +specified process and all its current children. +.El +.Pp +The +.Fa trpoints +argument specifies the trace points of interest. +The defined trace points are: +.Bl -column KTRFAC_SYSCALLXXX -offset indent +.It "KTRFAC_SYSCALL Trace system calls." +.It "KTRFAC_SYSRET Trace return values from system calls." +.It "KTRFAC_NAMEI Trace name lookup operations." +.It "KTRFAC_GENIO Trace all I/O (note that this option can" +generate much output). +.It "KTRFAC_PSIG Trace posted signals." +.It "KTRFAC_CSW Trace context switch points." +.It "KTRFAC_INHERIT Inherit tracing to future children." +.El +.Pp +Each tracing event outputs a record composed of a generic header +followed by a trace point specific structure. +The generic header is: +.Bd -literal +struct ktr_header { + int ktr_len; /* length of buf */ + short ktr_type; /* trace record type */ + pid_t ktr_pid; /* process id */ + char ktr_comm[MAXCOMLEN+1]; /* command name */ + struct timeval ktr_time; /* timestamp */ + caddr_t ktr_buf; +}; +.Ed +.Pp +The +.Va ktr_len +field specifies the length of the +.Va ktr_type +data that follows this header. +The +.Va ktr_pid +and +.Va ktr_comm +fields specify the process and command generating the record. +The +.Va ktr_time +field gives the time (with microsecond resolution) +that the record was generated. +The +.Va ktr_buf +is an internal kernel pointer and is not useful. +.Pp +The generic header is followed by +.Va ktr_len +bytes of a +.Va ktr_type +record. +The type specific records are defined in the +.In sys/ktrace.h +include file. +.Sh SYSCTL TUNABLES +The following +.Xr sysctl 8 +tunables influence the behaviour of +.Fn ktrace : +.Bl -tag -width indent +.It Va kern.ktrace.geniosize +bounds the amount of data a traced I/O request will log +to the trace file. +.It Va kern.ktrace.request_pool +bounds the number of trace events being logged at a time. +.El +.Pp +Sysctl tunables that control process debuggability (as determined by +.Xr p_candebug 9 ) +also affect the operation of +.Fn ktrace . +.Sh RETURN VALUES +.Rv -std ktrace +.Sh ERRORS +The +.Fn ktrace +system call +will fail if: +.Bl -tag -width Er +.It Bq Er ENOTDIR +A component of the path prefix is not a directory. +.It Bq Er ENAMETOOLONG +A component of a pathname exceeded 255 characters, +or an entire path name exceeded 1023 characters. +.It Bq Er ENOENT +The named tracefile does not exist. +.It Bq Er EACCES +Search permission is denied for a component of the path prefix. +.It Bq Er ELOOP +Too many symbolic links were encountered in translating the pathname. +.It Bq Er EIO +An I/O error occurred while reading from or writing to the file system. +.It Bq Er ENOSYS +The kernel was not compiled with +.Nm +support. +.El +.Pp +A thread may be unable to log one or more tracing events due to a +temporary shortage of resources. +This condition is remembered by the kernel, and the next tracing request +that succeeds will have the flag +.Li KTR_DROP +set in its +.Va ktr_type +field. +.Sh SEE ALSO +.Xr kdump 1 , +.Xr ktrace 1 , +.Xr utrace 2 , +.Xr sysctl 8 , +.Xr p_candebug 9 +.Sh HISTORY +The +.Fn ktrace +system call first appeared in +.Bx 4.4 . |
