1 /*- 2 * Copyright (c) 1989, 1990 William F. Jolitz 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * William Jolitz. 8 * 9 * %sccs.include.redist.c% 10 * 11 * @(#)segments.h 8.1 (Berkeley) 06/11/93 12 */ 13 14 /* 15 * 386 Segmentation Data Structures and definitions 16 * William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989 17 */ 18 19 /* 20 * Selectors 21 */ 22 23 #define ISPL(s) ((s)&3) /* what is the priority level of a selector */ 24 #define SEL_KPL 0 /* kernel priority level */ 25 #define SEL_UPL 3 /* user priority level */ 26 #define ISLDT(s) ((s)&SEL_LDT) /* is it local or global */ 27 #define SEL_LDT 4 /* local descriptor table */ 28 #define IDXSEL(s) (((s)>>3) & 0x1fff) /* index of selector */ 29 #define LSEL(s,r) (((s)<<3) | SEL_LDT | r) /* a local selector */ 30 #define GSEL(s,r) (((s)<<3) | r) /* a global selector */ 31 32 /* 33 * Memory and System segment descriptors 34 */ 35 struct segment_descriptor { 36 unsigned sd_lolimit:16 ; /* segment extent (lsb) */ 37 unsigned sd_lobase:24 ; /* segment base address (lsb) */ 38 unsigned sd_type:5 ; /* segment type */ 39 unsigned sd_dpl:2 ; /* segment descriptor priority level */ 40 unsigned sd_p:1 ; /* segment descriptor present */ 41 unsigned sd_hilimit:4 ; /* segment extent (msb) */ 42 unsigned sd_xx:2 ; /* unused */ 43 unsigned sd_def32:1 ; /* default 32 vs 16 bit size */ 44 unsigned sd_gran:1 ; /* limit granularity (byte/page units)*/ 45 unsigned sd_hibase:8 ; /* segment base address (msb) */ 46 } ; 47 48 /* 49 * Gate descriptors (e.g. indirect descriptors) 50 */ 51 struct gate_descriptor { 52 unsigned gd_looffset:16 ; /* gate offset (lsb) */ 53 unsigned gd_selector:16 ; /* gate segment selector */ 54 unsigned gd_stkcpy:5 ; /* number of stack wds to cpy */ 55 unsigned gd_xx:3 ; /* unused */ 56 unsigned gd_type:5 ; /* segment type */ 57 unsigned gd_dpl:2 ; /* segment descriptor priority level */ 58 unsigned gd_p:1 ; /* segment descriptor present */ 59 unsigned gd_hioffset:16 ; /* gate offset (msb) */ 60 } ; 61 62 /* 63 * Generic descriptor 64 */ 65 union descriptor { 66 struct segment_descriptor sd; 67 struct gate_descriptor gd; 68 }; 69 #define d_type gd.gd_type 70 71 /* system segments and gate types */ 72 #define SDT_SYSNULL 0 /* system null */ 73 #define SDT_SYS286TSS 1 /* system 286 TSS available */ 74 #define SDT_SYSLDT 2 /* system local descriptor table */ 75 #define SDT_SYS286BSY 3 /* system 286 TSS busy */ 76 #define SDT_SYS286CGT 4 /* system 286 call gate */ 77 #define SDT_SYSTASKGT 5 /* system task gate */ 78 #define SDT_SYS286IGT 6 /* system 286 interrupt gate */ 79 #define SDT_SYS286TGT 7 /* system 286 trap gate */ 80 #define SDT_SYSNULL2 8 /* system null again */ 81 #define SDT_SYS386TSS 9 /* system 386 TSS available */ 82 #define SDT_SYSNULL3 10 /* system null again */ 83 #define SDT_SYS386BSY 11 /* system 386 TSS busy */ 84 #define SDT_SYS386CGT 12 /* system 386 call gate */ 85 #define SDT_SYSNULL4 13 /* system null again */ 86 #define SDT_SYS386IGT 14 /* system 386 interrupt gate */ 87 #define SDT_SYS386TGT 15 /* system 386 trap gate */ 88 89 /* memory segment types */ 90 #define SDT_MEMRO 16 /* memory read only */ 91 #define SDT_MEMROA 17 /* memory read only accessed */ 92 #define SDT_MEMRW 18 /* memory read write */ 93 #define SDT_MEMRWA 19 /* memory read write accessed */ 94 #define SDT_MEMROD 20 /* memory read only expand dwn limit */ 95 #define SDT_MEMRODA 21 /* memory read only expand dwn limit accessed */ 96 #define SDT_MEMRWD 22 /* memory read write expand dwn limit */ 97 #define SDT_MEMRWDA 23 /* memory read write expand dwn limit acessed */ 98 #define SDT_MEME 24 /* memory execute only */ 99 #define SDT_MEMEA 25 /* memory execute only accessed */ 100 #define SDT_MEMER 26 /* memory execute read */ 101 #define SDT_MEMERA 27 /* memory execute read accessed */ 102 #define SDT_MEMEC 28 /* memory execute only conforming */ 103 #define SDT_MEMEAC 29 /* memory execute only accessed conforming */ 104 #define SDT_MEMERC 30 /* memory execute read conforming */ 105 #define SDT_MEMERAC 31 /* memory execute read accessed conforming */ 106 107 /* is memory segment descriptor pointer ? */ 108 #define ISMEMSDP(s) ((s->d_type) >= SDT_MEMRO && (s->d_type) <= SDT_MEMERAC) 109 110 /* is 286 gate descriptor pointer ? */ 111 #define IS286GDP(s) (((s->d_type) >= SDT_SYS286CGT \ 112 && (s->d_type) < SDT_SYS286TGT)) 113 114 /* is 386 gate descriptor pointer ? */ 115 #define IS386GDP(s) (((s->d_type) >= SDT_SYS386CGT \ 116 && (s->d_type) < SDT_SYS386TGT)) 117 118 /* is gate descriptor pointer ? */ 119 #define ISGDP(s) (IS286GDP(s) || IS386GDP(s)) 120 121 /* is segment descriptor pointer ? */ 122 #define ISSDP(s) (ISMEMSDP(s) || !ISGDP(s)) 123 124 /* is system segment descriptor pointer ? */ 125 #define ISSYSSDP(s) (!ISMEMSDP(s) && !ISGDP(s)) 126 127 /* 128 * Software definitions are in this convenient format, 129 * which are translated into inconvenient segment descriptors 130 * when needed to be used by the 386 hardware 131 */ 132 133 struct soft_segment_descriptor { 134 unsigned ssd_base ; /* segment base address */ 135 unsigned ssd_limit ; /* segment extent */ 136 unsigned ssd_type:5 ; /* segment type */ 137 unsigned ssd_dpl:2 ; /* segment descriptor priority level */ 138 unsigned ssd_p:1 ; /* segment descriptor present */ 139 unsigned ssd_xx:4 ; /* unused */ 140 unsigned ssd_xx1:2 ; /* unused */ 141 unsigned ssd_def32:1 ; /* default 32 vs 16 bit size */ 142 unsigned ssd_gran:1 ; /* limit granularity (byte/page units)*/ 143 }; 144 145 extern ssdtosd() ; /* to decode a ssd */ 146 extern sdtossd() ; /* to encode a sd */ 147 148 /* 149 * region descriptors, used to load gdt/idt tables before segments yet exist 150 */ 151 struct region_descriptor { 152 unsigned rd_limit:16 ; /* segment extent */ 153 char *rd_base; /* base address */ 154 }; 155 156 /* 157 * Segment Protection Exception code bits 158 */ 159 160 #define SEGEX_EXT 0x01 /* recursive or externally induced */ 161 #define SEGEX_IDT 0x02 /* interrupt descriptor table */ 162 #define SEGEX_TI 0x04 /* local descriptor table */ 163 /* other bits are affected descriptor index */ 164 #define SEGEX_IDX(s) ((s)>>3)&0x1fff) 165