_set_tp.c revision 133754
1230557Sjimharris/*-
2230557Sjimharris * Copyright (c) 2004 Doug Rabson
3230557Sjimharris * All rights reserved.
4230557Sjimharris *
5230557Sjimharris * Redistribution and use in source and binary forms, with or without
6230557Sjimharris * modification, are permitted provided that the following conditions
7230557Sjimharris * are met:
8230557Sjimharris * 1. Redistributions of source code must retain the above copyright
9230557Sjimharris *    notice, this list of conditions and the following disclaimer.
10230557Sjimharris * 2. Redistributions in binary form must reproduce the above copyright
11230557Sjimharris *    notice, this list of conditions and the following disclaimer in the
12230557Sjimharris *    documentation and/or other materials provided with the distribution.
13230557Sjimharris *
14230557Sjimharris * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15230557Sjimharris * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16230557Sjimharris * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17230557Sjimharris * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18230557Sjimharris * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19230557Sjimharris * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20230557Sjimharris * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21230557Sjimharris * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22230557Sjimharris * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23230557Sjimharris * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24230557Sjimharris * SUCH DAMAGE.
25230557Sjimharris *
26230557Sjimharris *	$FreeBSD: head/lib/libc/i386/gen/_set_tp.c 133754 2004-08-15 16:18:52Z dfr $
27230557Sjimharris */
28230557Sjimharris
29230557Sjimharris#include <string.h>
30230557Sjimharris#include <stdint.h>
31230557Sjimharris#include <machine/segments.h>
32230557Sjimharris#include <machine/sysarch.h>
33230557Sjimharris
34230557Sjimharrisvoid
35230557Sjimharris_set_tp(void *tp)
36230557Sjimharris{
37230557Sjimharris	union descriptor ldt;
38230557Sjimharris	int sel;
39230557Sjimharris
40230557Sjimharris	memset(&ldt, 0, sizeof(ldt));
41230557Sjimharris	ldt.sd.sd_lolimit = 0xffff;	/* 4G limit */
42230557Sjimharris	ldt.sd.sd_lobase = ((uintptr_t)tp) & 0xffffff;
43230557Sjimharris	ldt.sd.sd_type = SDT_MEMRWA;
44230557Sjimharris	ldt.sd.sd_dpl = SEL_UPL;
45230557Sjimharris	ldt.sd.sd_p = 1;		/* present */
46230557Sjimharris	ldt.sd.sd_hilimit = 0xf;	/* 4G limit */
47230557Sjimharris	ldt.sd.sd_def32 = 1;		/* 32 bit */
48230557Sjimharris	ldt.sd.sd_gran = 1;		/* limit in pages */
49230557Sjimharris	ldt.sd.sd_hibase = (((uintptr_t)tp) >> 24) & 0xff;
50230557Sjimharris	sel = i386_set_ldt(LDT_AUTO_ALLOC, &ldt, 1);
51230557Sjimharris	__asm __volatile("movl %0,%%gs" : : "rm" ((sel << 3) | 7));
52230557Sjimharris}
53230557Sjimharris