segments.h revision 621
1/*- 2 * Copyright (c) 1989, 1990 William F. Jolitz 3 * Copyright (c) 1990 The Regents of the University of California. 4 * All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * William Jolitz. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by the University of 20 * California, Berkeley and its contributors. 21 * 4. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * from: @(#)segments.h 7.1 (Berkeley) 5/9/91 38 * $Id$ 39 */ 40 41/* 42 * 386 Segmentation Data Structures and definitions 43 * William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989 44 */ 45 46/* 47 * Selectors 48 */ 49 50#define ISPL(s) ((s)&3) /* what is the priority level of a selector */ 51#define SEL_KPL 0 /* kernel priority level */ 52#define SEL_UPL 3 /* user priority level */ 53#define ISLDT(s) ((s)&SEL_LDT) /* is it local or global */ 54#define SEL_LDT 4 /* local descriptor table */ 55#define IDXSEL(s) (((s)>>3) & 0x1fff) /* index of selector */ 56#define LSEL(s,r) (((s)<<3) | SEL_LDT | r) /* a local selector */ 57#define GSEL(s,r) (((s)<<3) | r) /* a global selector */ 58 59/* 60 * Memory and System segment descriptors 61 */ 62struct segment_descriptor { 63 unsigned sd_lolimit:16 ; /* segment extent (lsb) */ 64 unsigned sd_lobase:24 ; /* segment base address (lsb) */ 65 unsigned sd_type:5 ; /* segment type */ 66 unsigned sd_dpl:2 ; /* segment descriptor priority level */ 67 unsigned sd_p:1 ; /* segment descriptor present */ 68 unsigned sd_hilimit:4 ; /* segment extent (msb) */ 69 unsigned sd_xx:2 ; /* unused */ 70 unsigned sd_def32:1 ; /* default 32 vs 16 bit size */ 71 unsigned sd_gran:1 ; /* limit granularity (byte/page units)*/ 72 unsigned sd_hibase:8 ; /* segment base address (msb) */ 73} ; 74 75/* 76 * Gate descriptors (e.g. indirect descriptors) 77 */ 78struct gate_descriptor { 79 unsigned gd_looffset:16 ; /* gate offset (lsb) */ 80 unsigned gd_selector:16 ; /* gate segment selector */ 81 unsigned gd_stkcpy:5 ; /* number of stack wds to cpy */ 82 unsigned gd_xx:3 ; /* unused */ 83 unsigned gd_type:5 ; /* segment type */ 84 unsigned gd_dpl:2 ; /* segment descriptor priority level */ 85 unsigned gd_p:1 ; /* segment descriptor present */ 86 unsigned gd_hioffset:16 ; /* gate offset (msb) */ 87} ; 88 89/* 90 * Generic descriptor 91 */ 92union descriptor { 93 struct segment_descriptor sd; 94 struct gate_descriptor gd; 95}; 96 97 /* system segments and gate types */ 98#define SDT_SYSNULL 0 /* system null */ 99#define SDT_SYS286TSS 1 /* system 286 TSS available */ 100#define SDT_SYSLDT 2 /* system local descriptor table */ 101#define SDT_SYS286BSY 3 /* system 286 TSS busy */ 102#define SDT_SYS286CGT 4 /* system 286 call gate */ 103#define SDT_SYSTASKGT 5 /* system task gate */ 104#define SDT_SYS286IGT 6 /* system 286 interrupt gate */ 105#define SDT_SYS286TGT 7 /* system 286 trap gate */ 106#define SDT_SYSNULL2 8 /* system null again */ 107#define SDT_SYS386TSS 9 /* system 386 TSS available */ 108#define SDT_SYSNULL3 10 /* system null again */ 109#define SDT_SYS386BSY 11 /* system 386 TSS busy */ 110#define SDT_SYS386CGT 12 /* system 386 call gate */ 111#define SDT_SYSNULL4 13 /* system null again */ 112#define SDT_SYS386IGT 14 /* system 386 interrupt gate */ 113#define SDT_SYS386TGT 15 /* system 386 trap gate */ 114 115 /* memory segment types */ 116#define SDT_MEMRO 16 /* memory read only */ 117#define SDT_MEMROA 17 /* memory read only accessed */ 118#define SDT_MEMRW 18 /* memory read write */ 119#define SDT_MEMRWA 19 /* memory read write accessed */ 120#define SDT_MEMROD 20 /* memory read only expand dwn limit */ 121#define SDT_MEMRODA 21 /* memory read only expand dwn limit accessed */ 122#define SDT_MEMRWD 22 /* memory read write expand dwn limit */ 123#define SDT_MEMRWDA 23 /* memory read write expand dwn limit acessed */ 124#define SDT_MEME 24 /* memory execute only */ 125#define SDT_MEMEA 25 /* memory execute only accessed */ 126#define SDT_MEMER 26 /* memory execute read */ 127#define SDT_MEMERA 27 /* memory execute read accessed */ 128#define SDT_MEMEC 28 /* memory execute only conforming */ 129#define SDT_MEMEAC 29 /* memory execute only accessed conforming */ 130#define SDT_MEMERC 30 /* memory execute read conforming */ 131#define SDT_MEMERAC 31 /* memory execute read accessed conforming */ 132 133/* is memory segment descriptor pointer ? */ 134#define ISMEMSDP(s) ((s->d_type) >= SDT_MEMRO && (s->d_type) <= SDT_MEMERAC) 135 136/* is 286 gate descriptor pointer ? */ 137#define IS286GDP(s) (((s->d_type) >= SDT_SYS286CGT \ 138 && (s->d_type) < SDT_SYS286TGT)) 139 140/* is 386 gate descriptor pointer ? */ 141#define IS386GDP(s) (((s->d_type) >= SDT_SYS386CGT \ 142 && (s->d_type) < SDT_SYS386TGT)) 143 144/* is gate descriptor pointer ? */ 145#define ISGDP(s) (IS286GDP(s) || IS386GDP(s)) 146 147/* is segment descriptor pointer ? */ 148#define ISSDP(s) (ISMEMSDP(s) || !ISGDP(s)) 149 150/* is system segment descriptor pointer ? */ 151#define ISSYSSDP(s) (!ISMEMSDP(s) && !ISGDP(s)) 152 153/* 154 * Software definitions are in this convenient format, 155 * which are translated into inconvenient segment descriptors 156 * when needed to be used by the 386 hardware 157 */ 158 159struct soft_segment_descriptor { 160 unsigned ssd_base ; /* segment base address */ 161 unsigned ssd_limit ; /* segment extent */ 162 unsigned ssd_type:5 ; /* segment type */ 163 unsigned ssd_dpl:2 ; /* segment descriptor priority level */ 164 unsigned ssd_p:1 ; /* segment descriptor present */ 165 unsigned ssd_xx:4 ; /* unused */ 166 unsigned ssd_xx1:2 ; /* unused */ 167 unsigned ssd_def32:1 ; /* default 32 vs 16 bit size */ 168 unsigned ssd_gran:1 ; /* limit granularity (byte/page units)*/ 169}; 170 171extern ssdtosd() ; /* to decode a ssd */ 172extern sdtossd() ; /* to encode a sd */ 173 174/* 175 * region descriptors, used to load gdt/idt tables before segments yet exist. 176 */ 177struct region_descriptor { 178 unsigned rd_limit:16; /* segment extent */ 179 unsigned rd_base:32; /* base address */ 180}; 181 182/* 183 * Segment Protection Exception code bits 184 */ 185 186#define SEGEX_EXT 0x01 /* recursive or externally induced */ 187#define SEGEX_IDT 0x02 /* interrupt descriptor table */ 188#define SEGEX_TI 0x04 /* local descriptor table */ 189 /* other bits are affected descriptor index */ 190#define SEGEX_IDX(s) ((s)>>3)&0x1fff) 191 192/* 193 * Size of IDT table 194 */ 195 196#define NIDT 256 197#define NRSVIDT 32 /* reserved entries for cpu exceptions */ 198