1994-01-31 12:05:32 +00:00
|
|
|
.\" Copyright (c) 1980, 1991 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. All advertising materials mentioning features or use of this software
|
|
|
|
|
.\" must display the following acknowledgement:
|
|
|
|
|
.\" This product includes software developed by the University of
|
|
|
|
|
.\" California, Berkeley and its contributors.
|
|
|
|
|
.\" 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.
|
|
|
|
|
.\"
|
|
|
|
|
.\" from: @(#)fork.2 6.5 (Berkeley) 3/10/91
|
1999-08-28 00:22:10 +00:00
|
|
|
.\" $FreeBSD$
|
1994-01-31 12:05:32 +00:00
|
|
|
.\"
|
|
|
|
|
.Dd September 20, 1993
|
|
|
|
|
.Dt I386_GET_LDT 2
|
2001-07-10 13:41:46 +00:00
|
|
|
.Os
|
1994-01-31 12:05:32 +00:00
|
|
|
.Sh NAME
|
|
|
|
|
.Nm i386_get_ldt ,
|
|
|
|
|
.Nm i386_set_ldt
|
|
|
|
|
.Nd manage i386 per-process Local Descriptor Table entries
|
2000-04-21 09:42:15 +00:00
|
|
|
.Sh LIBRARY
|
|
|
|
|
.Lb libc
|
1994-01-31 12:05:32 +00:00
|
|
|
.Sh SYNOPSIS
|
2001-10-01 16:09:29 +00:00
|
|
|
.In machine/segments.h
|
|
|
|
|
.In machine/sysarch.h
|
1994-01-31 12:05:32 +00:00
|
|
|
.Ft int
|
|
|
|
|
.Fn i386_get_ldt "int start_sel" "union descriptor *descs" "int num_sels"
|
|
|
|
|
.Ft int
|
|
|
|
|
.Fn i386_set_ldt "int start_sel" "union descriptor *descs" "int num_sels"
|
|
|
|
|
.Sh DESCRIPTION
|
2002-12-18 12:39:25 +00:00
|
|
|
The
|
1994-01-31 12:05:32 +00:00
|
|
|
.Fn i386_get_ldt
|
2002-12-18 12:39:25 +00:00
|
|
|
system call
|
1994-01-31 12:05:32 +00:00
|
|
|
will return the list of i386 descriptors that the process has in its
|
|
|
|
|
LDT.
|
2002-12-18 12:39:25 +00:00
|
|
|
The
|
1994-01-31 12:05:32 +00:00
|
|
|
.Fn i386_set_ldt
|
2002-12-18 12:39:25 +00:00
|
|
|
system call
|
1994-01-31 12:05:32 +00:00
|
|
|
will set a list of i386 descriptors for the current process in its
|
|
|
|
|
LDT.
|
|
|
|
|
Both routines accept a starting selector number
|
2001-08-10 17:35:21 +00:00
|
|
|
.Fa start_sel ,
|
|
|
|
|
an array of memory that
|
2001-07-15 07:53:42 +00:00
|
|
|
will contain the descriptors to be set or returned
|
2001-08-10 17:35:21 +00:00
|
|
|
.Fa descs ,
|
|
|
|
|
and the number of entries to set or return
|
1994-01-31 12:05:32 +00:00
|
|
|
.Fa num_sels .
|
|
|
|
|
.Pp
|
|
|
|
|
The argument
|
|
|
|
|
.Fa descs
|
|
|
|
|
can be either segment_descriptor or gate_descriptor and are defined in
|
2003-09-08 19:57:22 +00:00
|
|
|
.In i386/segments.h .
|
1998-06-04 21:06:07 +00:00
|
|
|
These structures are defined by the architecture
|
1994-01-31 12:05:32 +00:00
|
|
|
as disjoint bit-fields, so care must be taken in constructing them.
|
2003-07-31 02:13:48 +00:00
|
|
|
.Pp
|
2004-07-02 19:07:33 +00:00
|
|
|
If
|
2003-07-31 02:13:48 +00:00
|
|
|
.Fa start_sel
|
2004-07-02 19:07:33 +00:00
|
|
|
is
|
2003-08-04 19:11:56 +00:00
|
|
|
.Em LDT_AUTO_ALLOC ,
|
2003-07-31 02:13:48 +00:00
|
|
|
.Fa num_sels
|
2004-07-02 19:07:33 +00:00
|
|
|
is 1 and the descriptor pointed to by
|
2003-07-31 02:13:48 +00:00
|
|
|
.Fa descs
|
|
|
|
|
is legal, then
|
|
|
|
|
.Fn i386_set_ldt
|
2004-07-02 19:07:33 +00:00
|
|
|
will allocate a descriptor and return its
|
2003-07-31 02:13:48 +00:00
|
|
|
selector number.
|
|
|
|
|
.Pp
|
2004-07-02 19:07:33 +00:00
|
|
|
If
|
2003-07-31 02:13:48 +00:00
|
|
|
.Fa num_descs
|
|
|
|
|
is 1,
|
|
|
|
|
.Fa start_sels
|
2004-07-02 19:07:33 +00:00
|
|
|
is valid, and
|
2003-07-31 02:13:48 +00:00
|
|
|
.Fa descs
|
2004-07-02 19:07:33 +00:00
|
|
|
is NULL, then
|
2003-07-31 02:13:48 +00:00
|
|
|
.Fn i386_set_ldt
|
|
|
|
|
will free that descriptor
|
|
|
|
|
(making it available to be reallocated again later).
|
|
|
|
|
.Pp
|
2004-07-02 19:07:33 +00:00
|
|
|
If
|
|
|
|
|
.Fa num_descs
|
|
|
|
|
is 0,
|
2003-07-31 02:13:48 +00:00
|
|
|
.Fa start_sels
|
|
|
|
|
is 0 and
|
|
|
|
|
.Fa descs
|
|
|
|
|
is NULL then, as a special case,
|
|
|
|
|
.Fn i386_set_ldt
|
|
|
|
|
will free all descriptors.
|
1994-01-31 12:05:32 +00:00
|
|
|
.Sh RETURN VALUES
|
|
|
|
|
Upon successful completion,
|
|
|
|
|
.Fn i386_get_ldt
|
|
|
|
|
returns the number of descriptors currently in the LDT.
|
2002-12-18 12:39:25 +00:00
|
|
|
The
|
1994-01-31 12:05:32 +00:00
|
|
|
.Fn i386_set_ldt
|
2002-12-18 12:39:25 +00:00
|
|
|
system call
|
1994-01-31 12:05:32 +00:00
|
|
|
returns the first selector set.
|
2003-07-31 02:13:48 +00:00
|
|
|
In the case when a descriptor is allocated by the kernel, its number will
|
|
|
|
|
be returned.
|
1994-01-31 12:05:32 +00:00
|
|
|
Otherwise, a value of -1 is returned and the global
|
|
|
|
|
variable
|
|
|
|
|
.Va errno
|
|
|
|
|
is set to indicate the error.
|
|
|
|
|
.Sh ERRORS
|
2002-12-18 12:39:25 +00:00
|
|
|
The
|
1994-01-31 12:05:32 +00:00
|
|
|
.Fn i386_get_ldt
|
|
|
|
|
and
|
|
|
|
|
.Fn i386_set_ldt
|
2002-12-18 12:39:25 +00:00
|
|
|
system calls
|
1994-01-31 12:05:32 +00:00
|
|
|
will fail if:
|
2000-05-06 12:07:59 +00:00
|
|
|
.Bl -tag -width Er
|
1994-01-31 12:05:32 +00:00
|
|
|
.It Bq Er EINVAL
|
2002-12-19 09:40:28 +00:00
|
|
|
An inappropriate value was used for
|
1994-01-31 12:05:32 +00:00
|
|
|
.Fa start_sel
|
|
|
|
|
or
|
|
|
|
|
.Fa num_sels .
|
1999-03-15 00:14:57 +00:00
|
|
|
.It Bq Er EACCES
|
1994-01-31 12:05:32 +00:00
|
|
|
The caller attempted to use a descriptor that would
|
|
|
|
|
circumvent protection or cause a failure.
|
|
|
|
|
.El
|
2000-11-17 11:44:16 +00:00
|
|
|
.Sh SEE ALSO
|
1994-01-31 12:05:32 +00:00
|
|
|
i386 Microprocessor Programmer's Reference Manual, Intel
|
|
|
|
|
.Sh WARNING
|
|
|
|
|
You can really hose your process using this.
|
