xref: /freebsd/sys/i386/include/segments.h (revision 29363fb446372cb3f10bc98664e9767c53fbb457)

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1989, 1990 William F. Jolitz
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * William Jolitz.
 *
 * 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.
 */

#ifndef _MACHINE_SEGMENTS_H_
#define	_MACHINE_SEGMENTS_H_

/*
 * 386 Segmentation Data Structures and definitions
 *	William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989
 */

#include <x86/segments.h>

/*
 * Software definitions are in this convenient format,
 * which are translated into inconvenient segment descriptors
 * when needed to be used by the 386 hardware
 */

struct	soft_segment_descriptor	{
	unsigned ssd_base ;		/* segment base address  */
	unsigned ssd_limit ;		/* segment extent */
	unsigned ssd_type:5 ;		/* segment type */
	unsigned ssd_dpl:2 ;		/* segment descriptor priority level */
	unsigned ssd_p:1 ;		/* segment descriptor present */
	unsigned ssd_xx:4 ;		/* unused */
	unsigned ssd_xx1:2 ;		/* unused */
	unsigned ssd_def32:1 ;		/* default 32 vs 16 bit size */
	unsigned ssd_gran:1 ;		/* limit granularity (byte/page units)*/
};

/*
 * region descriptors, used to load gdt/idt tables before segments yet exist.
 */
struct region_descriptor {
	unsigned rd_limit:16;		/* segment extent */
	unsigned rd_base:32 __packed;	/* base address  */
};

/*
 * Segment Protection Exception code bits
 */

#define	SEGEX_EXT	0x01	/* recursive or externally induced */
#define	SEGEX_IDT	0x02	/* interrupt descriptor table */
#define	SEGEX_TI	0x04	/* local descriptor table */
				/* other bits are affected descriptor index */
#define SEGEX_IDX(s)	(((s)>>3)&0x1fff)

#ifdef _KERNEL
extern int	_default_ldt;
extern union descriptor *gdt;
extern union descriptor *ldt;
extern struct soft_segment_descriptor gdt_segs[];
extern struct gate_descriptor *idt;

void	lgdt(struct region_descriptor *rdp);
void	sdtossd(struct segment_descriptor *sdp,
	    struct soft_segment_descriptor *ssdp);
void	ssdtosd(struct soft_segment_descriptor *ssdp,
	    struct segment_descriptor *sdp);
#endif /* _KERNEL */

#endif /* !_MACHINE_SEGMENTS_H_ */