_set_tp.c revision 145571
1/*- 2 * Copyright (c) 2004 Doug Rabson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: head/lib/libc/i386/gen/_set_tp.c 145571 2005-04-26 20:46:11Z peter $ 27 */ 28 29#include <string.h> 30#include <stdint.h> 31#include <machine/segments.h> 32#include <machine/sysarch.h> 33 34void 35_set_tp(void *tp) 36{ 37#ifndef COMPAT_32BIT 38 union descriptor ldt; 39 int error, sel; 40 41 error = i386_set_gsbase(tp); 42 if (error == 0) 43 return; 44 memset(&ldt, 0, sizeof(ldt)); 45 ldt.sd.sd_lolimit = 0xffff; /* 4G limit */ 46 ldt.sd.sd_lobase = ((uintptr_t)tp) & 0xffffff; 47 ldt.sd.sd_type = SDT_MEMRWA; 48 ldt.sd.sd_dpl = SEL_UPL; 49 ldt.sd.sd_p = 1; /* present */ 50 ldt.sd.sd_hilimit = 0xf; /* 4G limit */ 51 ldt.sd.sd_def32 = 1; /* 32 bit */ 52 ldt.sd.sd_gran = 1; /* limit in pages */ 53 ldt.sd.sd_hibase = (((uintptr_t)tp) >> 24) & 0xff; 54 sel = i386_set_ldt(LDT_AUTO_ALLOC, &ldt, 1); 55 __asm __volatile("movl %0,%%gs" : : "rm" ((sel << 3) | 7)); 56#else 57 i386_set_gsbase(tp); 58#endif 59} 60