205 lines
6.2 KiB
Groff
205 lines
6.2 KiB
Groff
.\" 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 March 31, 2016
|
|
.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 Ta "Enable trace points specified in"
|
|
.Fa trpoints .
|
|
.It KTROP_CLEAR Ta "Disable trace points specified in"
|
|
.Fa trpoints .
|
|
.It KTROP_CLEARFILE Ta "Stop all tracing."
|
|
.It KTRFLAG_DESCEND Ta "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_PROCCTORXXX -offset indent
|
|
.It KTRFAC_SYSCALL Ta "Trace system calls."
|
|
.It KTRFAC_SYSRET Ta "Trace return values from system calls."
|
|
.It KTRFAC_NAMEI Ta "Trace name lookup operations."
|
|
.It KTRFAC_GENIO Ta "Trace all I/O (note that this option can"
|
|
generate much output).
|
|
.It KTRFAC_PSIG Ta "Trace posted signals."
|
|
.It KTRFAC_CSW Ta "Trace context switch points."
|
|
.It KTRFAC_USER Ta "Trace application-specific events."
|
|
.It KTRFAC_STRUCT Ta "Trace certain data structures."
|
|
.It KTRFAC_SYSCTL Ta "Trace sysctls."
|
|
.It KTRFAC_PROCCTOR Ta "Trace process construction."
|
|
.It KTRFAC_PROCDTOR Ta "Trace process destruction."
|
|
.It KTRFAC_CAPFAIL Ta "Trace capability failures."
|
|
.It KTRFAC_FAULT Ta "Trace page faults."
|
|
.It KTRFAC_FAULTEND Ta "Trace the end of page faults."
|
|
.It KTRFAC_INHERIT Ta "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 */
|
|
intptr_t ktr_tid; /* was ktr_buffer */
|
|
};
|
|
.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_tid
|
|
field holds a thread id.
|
|
.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 .
|