segments.h revision 5
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 * @(#)segments.h 7.1 (Berkeley) 5/9/91 38 */ 39 40/* 41 * 386 Segmentation Data Structures and definitions 42 * William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989 43 */ 44 45/* 46 * Selectors 47 */ 48 49#define ISPL(s) ((s)&3) /* what is the priority level of a selector */ 50#define SEL_KPL 0 /* kernel priority level */ 51#define SEL_UPL 3 /* user priority level */ 52#define ISLDT(s) ((s)&SEL_LDT) /* is it local or global */ 53#define SEL_LDT 4 /* local descriptor table */ 54#define IDXSEL(s) (((s)>>3) & 0x1fff) /* index of selector */ 55#define LSEL(s,r) (((s)<<3) | SEL_LDT | r) /* a local selector */ 56#define GSEL(s,r) (((s)<<3) | r) /* a global selector */ 57 58/* 59 * Memory and System segment descriptors 60 */ 61struct segment_descriptor { 62 unsigned sd_lolimit:16 ; /* segment extent (lsb) */ 63 unsigned sd_lobase:24 ; /* segment base address (lsb) */ 64 unsigned sd_type:5 ; /* segment type */ 65 unsigned sd_dpl:2 ; /* segment descriptor priority level */ 66 unsigned sd_p:1 ; /* segment descriptor present */ 67 unsigned sd_hilimit:4 ; /* segment extent (msb) */ 68 unsigned sd_xx:2 ; /* unused */ 69 unsigned sd_def32:1 ; /* default 32 vs 16 bit size */ 70 unsigned sd_gran:1 ; /* limit granularity (byte/page units)*/ 71 unsigned sd_hibase:8 ; /* segment base address (msb) */ 72} ; 73 74/* 75 * Gate descriptors (e.g. indirect descriptors) 76 */ 77struct gate_descriptor { 78 unsigned gd_looffset:16 ; /* gate offset (lsb) */ 79 unsigned gd_selector:16 ; /* gate segment selector */ 80 unsigned gd_stkcpy:5 ; /* number of stack wds to cpy */ 81 unsigned gd_xx:3 ; /* unused */ 82 unsigned gd_type:5 ; /* segment type */ 83 unsigned gd_dpl:2 ; /* segment descriptor priority level */ 84 unsigned gd_p:1 ; /* segment descriptor present */ 85 unsigned gd_hioffset:16 ; /* gate offset (msb) */ 86} ; 87 88/* 89 * Generic descriptor 90 */ 91union descriptor { 92 struct segment_descriptor sd; 93 struct gate_descriptor gd; 94}; 95 96 /* system segments and gate types */ 97#define SDT_SYSNULL 0 /* system null */ 98#define SDT_SYS286TSS 1 /* system 286 TSS available */ 99#define SDT_SYSLDT 2 /* system local descriptor table */ 100#define SDT_SYS286BSY 3 /* system 286 TSS busy */ 101#define SDT_SYS286CGT 4 /* system 286 call gate */ 102#define SDT_SYSTASKGT 5 /* system task gate */ 103#define SDT_SYS286IGT 6 /* system 286 interrupt gate */ 104#define SDT_SYS286TGT 7 /* system 286 trap gate */ 105#define SDT_SYSNULL2 8 /* system null again */ 106#define SDT_SYS386TSS 9 /* system 386 TSS available */ 107#define SDT_SYSNULL3 10 /* system null again */ 108#define SDT_SYS386BSY 11 /* system 386 TSS busy */ 109#define SDT_SYS386CGT 12 /* system 386 call gate */ 110#define SDT_SYSNULL4 13 /* system null again */ 111#define SDT_SYS386IGT 14 /* system 386 interrupt gate */ 112#define SDT_SYS386TGT 15 /* system 386 trap gate */ 113 114 /* memory segment types */ 115#define SDT_MEMRO 16 /* memory read only */ 116#define SDT_MEMROA 17 /* memory read only accessed */ 117#define SDT_MEMRW 18 /* memory read write */ 118#define SDT_MEMRWA 19 /* memory read write accessed */ 119#define SDT_MEMROD 20 /* memory read only expand dwn limit */ 120#define SDT_MEMRODA 21 /* memory read only expand dwn limit accessed */ 121#define SDT_MEMRWD 22 /* memory read write expand dwn limit */ 122#define SDT_MEMRWDA 23 /* memory read write expand dwn limit acessed */ 123#define SDT_MEME 24 /* memory execute only */ 124#define SDT_MEMEA 25 /* memory execute only accessed */ 125#define SDT_MEMER 26 /* memory execute read */ 126#define SDT_MEMERA 27 /* memory execute read accessed */ 127#define SDT_MEMEC 28 /* memory execute only conforming */ 128#define SDT_MEMEAC 29 /* memory execute only accessed conforming */ 129#define SDT_MEMERC 30 /* memory execute read conforming */ 130#define SDT_MEMERAC 31 /* memory execute read accessed conforming */ 131 132/* is memory segment descriptor pointer ? */ 133#define ISMEMSDP(s) ((s->d_type) >= SDT_MEMRO && (s->d_type) <= SDT_MEMERAC) 134 135/* is 286 gate descriptor pointer ? */ 136#define IS286GDP(s) (((s->d_type) >= SDT_SYS286CGT \ 137 && (s->d_type) < SDT_SYS286TGT)) 138 139/* is 386 gate descriptor pointer ? */ 140#define IS386GDP(s) (((s->d_type) >= SDT_SYS386CGT \ 141 && (s->d_type) < SDT_SYS386TGT)) 142 143/* is gate descriptor pointer ? */ 144#define ISGDP(s) (IS286GDP(s) || IS386GDP(s)) 145 146/* is segment descriptor pointer ? */ 147#define ISSDP(s) (ISMEMSDP(s) || !ISGDP(s)) 148 149/* is system segment descriptor pointer ? */ 150#define ISSYSSDP(s) (!ISMEMSDP(s) && !ISGDP(s)) 151 152/* 153 * Software definitions are in this convenient format, 154 * which are translated into inconvenient segment descriptors 155 * when needed to be used by the 386 hardware 156 */ 157 158struct soft_segment_descriptor { 159 unsigned ssd_base ; /* segment base address */ 160 unsigned ssd_limit ; /* segment extent */ 161 unsigned ssd_type:5 ; /* segment type */ 162 unsigned ssd_dpl:2 ; /* segment descriptor priority level */ 163 unsigned ssd_p:1 ; /* segment descriptor present */ 164 unsigned ssd_xx:4 ; /* unused */ 165 unsigned ssd_xx1:2 ; /* unused */ 166 unsigned ssd_def32:1 ; /* default 32 vs 16 bit size */ 167 unsigned ssd_gran:1 ; /* limit granularity (byte/page units)*/ 168}; 169 170extern ssdtosd() ; /* to decode a ssd */ 171extern sdtossd() ; /* to encode a sd */ 172 173/* 174 * region descriptors, used to load gdt/idt tables before segments yet exist. 175 */ 176struct region_descriptor { 177 unsigned rd_limit:16; /* segment extent */ 178 unsigned rd_base:32; /* base address */ 179}; 180 181/* 182 * Segment Protection Exception code bits 183 */ 184 185#define SEGEX_EXT 0x01 /* recursive or externally induced */ 186#define SEGEX_IDT 0x02 /* interrupt descriptor table */ 187#define SEGEX_TI 0x04 /* local descriptor table */ 188 /* other bits are affected descriptor index */ 189#define SEGEX_IDX(s) ((s)>>3)&0x1fff) 190 191/* 192 * Size of IDT table 193 */ 194 195#define NIDT 256 196#define NRSVIDT 32 /* reserved entries for cpu exceptions */ 197