xref: /freebsd/lib/libsys/i386/i386_set_watch.3 (revision 1a720cbec513210fa2e85c3882741ef2f6dc5f35)

.\" Copyright (c) 2000 Brian S. Dean
.\" All rights reserved.
.\"
.\" This man-page is based on a similar man-page by Jonathan Lemon
.\" which is copyrighted under the following conditions:
.\"
.\" 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.
.\"
.Dd August 24, 2000
.Dt I386_SET_WATCH 3
.Os
.Sh NAME
.Nm i386_clr_watch ,
.Nm i386_set_watch
.Nd manage i386 debug register values
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In machine/reg.h
.In machine/sysarch.h
.Ft int
.Fn i386_clr_watch "int watchnum" "struct dbreg *d"
.Ft int
.Fn i386_set_watch "int watchnum" "unsigned int watchaddr" "int size" "int access" "struct dbreg *d"
.Sh DESCRIPTION
The
.Fn i386_clr_watch
function
will disable the indicated watch point within the specified debug
register set.
.Pp
The
.Fn i386_set_watch
function
will set up the specified debug registers as indicated by the
arguments.
The
.Fa watchnum
argument specifies which watch register is used, 0, 1, 2, 3, or \-1.
If
.Fa watchnum
is \-1, a free watch register is found and used.
If there are no free
watch registers, an error code of \-1 is returned.
The
.Fa watchaddr
argument
specifies the watch address,
.Fa size
specifies the size in bytes of the area to be watched (1, 2, or 4 bytes),
and
.Fa access
specifies the type of watch point:
.Pp
.Bd -literal -offset indent -compact
DBREG_DR7_EXEC	  An execution breakpoint.
DBREG_DR7_WRONLY  Break only when the watch area is written to.
DBREG_DR7_RDWR	  Break when the watch area is read from or written
                  to.
.Ed
.Pp
Note that these functions do not actually set or clear breakpoints;
they manipulate the indicated debug register set.
You must use
.Xr ptrace 2
to retrieve and install the debug register values for a process.
.Sh RETURN VALUES
On success, the
.Fn i386_clr_watch
function returns 0.
On error, \-1 returned which indicates that
.Fa watchnum
is invalid (not in the range of 0-3).
If the specified watchnum was already disabled, no error is returned.
.Pp
On success, the
.Fn i386_set_watch
function returns the
.Fa watchnum
argument, or the watchnum actually used in the case where the specified
.Fa watchnum
was \-1.
On error, the
.Fn i386_set_watch
function returns \-1 indicating that the watchpoint could not established
because either no more watchpoints are available, or
.Fa watchnum ,
.Fa size ,
or
.Fa access
is invalid.
.Sh SEE ALSO
.Xr ptrace 2 ,
.Xr procfs 4
.Sh AUTHORS
This man page was written by
.An Brian S. Dean .