1*40467Sbill /* 2*40467Sbill * 386 Segmentation Data Structures and definitions 3*40467Sbill * William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989 4*40467Sbill */ 5*40467Sbill 6*40467Sbill /* 7*40467Sbill * Selectors 8*40467Sbill */ 9*40467Sbill 10*40467Sbill #define ISPL(s) ((s)&3) /* what is the priority level of a selector */ 11*40467Sbill #define SEL_KPL 0 /* kernel priority level */ 12*40467Sbill #define SEL_UPL 3 /* user priority level */ 13*40467Sbill #define ISLDT(s) ((s)&SEL_LDT) /* is it local or global */ 14*40467Sbill #define SEL_LDT 4 /* local descriptor table */ 15*40467Sbill #define IDXSEL(s) (((s)>>3) & 0x1fff) /* index of selector */ 16*40467Sbill #define LSEL(s,r) (((s)<<3) | SEL_LDT | r) /* a local selector */ 17*40467Sbill #define GSEL(s,r) (((s)<<3) | r) /* a global selector */ 18*40467Sbill 19*40467Sbill /* 20*40467Sbill * Memory and System segment descriptors 21*40467Sbill */ 22*40467Sbill struct segment_descriptor { 23*40467Sbill unsigned sd_lolimit:16 ; /* segment extent (lsb) */ 24*40467Sbill unsigned sd_lobase:24 ; /* segment base address (lsb) */ 25*40467Sbill unsigned sd_type:5 ; /* segment type */ 26*40467Sbill unsigned sd_dpl:2 ; /* segment descriptor priority level */ 27*40467Sbill unsigned sd_p:1 ; /* segment descriptor present */ 28*40467Sbill unsigned sd_hilimit:4 ; /* segment extent (msb) */ 29*40467Sbill unsigned sd_xx:2 ; /* unused */ 30*40467Sbill unsigned sd_def32:1 ; /* default 32 vs 16 bit size */ 31*40467Sbill unsigned sd_gran:1 ; /* limit granularity (byte/page units)*/ 32*40467Sbill unsigned sd_hibase:8 ; /* segment base address (msb) */ 33*40467Sbill } ; 34*40467Sbill 35*40467Sbill /* 36*40467Sbill * Gate descriptors (e.g. indirect descriptors) 37*40467Sbill */ 38*40467Sbill struct gate_descriptor { 39*40467Sbill unsigned gd_looffset:16 ; /* gate offset (lsb) */ 40*40467Sbill unsigned gd_selector:16 ; /* gate segment selector */ 41*40467Sbill unsigned gd_stkcpy:5 ; /* number of stack wds to cpy */ 42*40467Sbill unsigned gd_xx:3 ; /* unused */ 43*40467Sbill unsigned gd_type:5 ; /* segment type */ 44*40467Sbill unsigned gd_dpl:2 ; /* segment descriptor priority level */ 45*40467Sbill unsigned gd_p:1 ; /* segment descriptor present */ 46*40467Sbill unsigned gd_hioffset:16 ; /* gate offset (msb) */ 47*40467Sbill } ; 48*40467Sbill 49*40467Sbill /* 50*40467Sbill * Generic descriptor 51*40467Sbill */ 52*40467Sbill union descriptor { 53*40467Sbill struct segment_descriptor sd; 54*40467Sbill struct gate_descriptor gd; 55*40467Sbill }; 56*40467Sbill #define d_type gd.gd_type 57*40467Sbill 58*40467Sbill /* system segments and gate types */ 59*40467Sbill #define SDT_SYSNULL 0 /* system null */ 60*40467Sbill #define SDT_SYS286TSS 1 /* system 286 TSS available */ 61*40467Sbill #define SDT_SYSLDT 2 /* system local descriptor table */ 62*40467Sbill #define SDT_SYS286BSY 3 /* system 286 TSS busy */ 63*40467Sbill #define SDT_SYS286CGT 4 /* system 286 call gate */ 64*40467Sbill #define SDT_SYSTASKGT 5 /* system task gate */ 65*40467Sbill #define SDT_SYS286IGT 6 /* system 286 interrupt gate */ 66*40467Sbill #define SDT_SYS286TGT 7 /* system 286 trap gate */ 67*40467Sbill #define SDT_SYSNULL2 8 /* system null again */ 68*40467Sbill #define SDT_SYS386TSS 9 /* system 386 TSS available */ 69*40467Sbill #define SDT_SYSNULL3 10 /* system null again */ 70*40467Sbill #define SDT_SYS386BSY 11 /* system 386 TSS busy */ 71*40467Sbill #define SDT_SYS386CGT 12 /* system 386 call gate */ 72*40467Sbill #define SDT_SYSNULL4 13 /* system null again */ 73*40467Sbill #define SDT_SYS386IGT 14 /* system 386 interrupt gate */ 74*40467Sbill #define SDT_SYS386TGT 15 /* system 386 trap gate */ 75*40467Sbill 76*40467Sbill /* memory segment types */ 77*40467Sbill #define SDT_MEMRO 16 /* memory read only */ 78*40467Sbill #define SDT_MEMROA 17 /* memory read only accessed */ 79*40467Sbill #define SDT_MEMRW 18 /* memory read write */ 80*40467Sbill #define SDT_MEMRWA 19 /* memory read write accessed */ 81*40467Sbill #define SDT_MEMROD 20 /* memory read only expand dwn limit */ 82*40467Sbill #define SDT_MEMRODA 21 /* memory read only expand dwn limit accessed */ 83*40467Sbill #define SDT_MEMRWD 22 /* memory read write expand dwn limit */ 84*40467Sbill #define SDT_MEMRWDA 23 /* memory read write expand dwn limit acessed */ 85*40467Sbill #define SDT_MEME 24 /* memory execute only */ 86*40467Sbill #define SDT_MEMEA 25 /* memory execute only accessed */ 87*40467Sbill #define SDT_MEMER 26 /* memory execute read */ 88*40467Sbill #define SDT_MEMERA 27 /* memory execute read accessed */ 89*40467Sbill #define SDT_MEMEC 28 /* memory execute only conforming */ 90*40467Sbill #define SDT_MEMEAC 29 /* memory execute only accessed conforming */ 91*40467Sbill #define SDT_MEMERC 30 /* memory execute read conforming */ 92*40467Sbill #define SDT_MEMERAC 31 /* memory execute read accessed conforming */ 93*40467Sbill 94*40467Sbill /* is memory segment descriptor pointer ? */ 95*40467Sbill #define ISMEMSDP(s) ((s->d_type) >= SDT_MEMRO && (s->d_type) <= SDT_MEMERAC) 96*40467Sbill 97*40467Sbill /* is 286 gate descriptor pointer ? */ 98*40467Sbill #define IS286GDP(s) (((s->d_type) >= SDT_SYS286CGT \ 99*40467Sbill && (s->d_type) < SDT_SYS286TGT)) 100*40467Sbill 101*40467Sbill /* is 386 gate descriptor pointer ? */ 102*40467Sbill #define IS386GDP(s) (((s->d_type) >= SDT_SYS386CGT \ 103*40467Sbill && (s->d_type) < SDT_SYS386TGT)) 104*40467Sbill 105*40467Sbill /* is gate descriptor pointer ? */ 106*40467Sbill #define ISGDP(s) (IS286GDP(s) || IS386GDP(s)) 107*40467Sbill 108*40467Sbill /* is segment descriptor pointer ? */ 109*40467Sbill #define ISSDP(s) (ISMEMSDP(s) || !ISGDP(s)) 110*40467Sbill 111*40467Sbill /* is system segment descriptor pointer ? */ 112*40467Sbill #define ISSYSSDP(s) (!ISMEMSDP(s) && !ISGDP(s)) 113*40467Sbill 114*40467Sbill /* 115*40467Sbill * Software definitions are in this convenient format, 116*40467Sbill * which are translated into inconvenient segment descriptors 117*40467Sbill * when needed to be used by the 386 hardware 118*40467Sbill */ 119*40467Sbill 120*40467Sbill struct soft_segment_descriptor { 121*40467Sbill unsigned ssd_base ; /* segment base address */ 122*40467Sbill unsigned ssd_limit ; /* segment extent */ 123*40467Sbill unsigned ssd_type:5 ; /* segment type */ 124*40467Sbill unsigned ssd_dpl:2 ; /* segment descriptor priority level */ 125*40467Sbill unsigned ssd_p:1 ; /* segment descriptor present */ 126*40467Sbill unsigned ssd_xx:4 ; /* unused */ 127*40467Sbill unsigned ssd_xx1:2 ; /* unused */ 128*40467Sbill unsigned ssd_def32:1 ; /* default 32 vs 16 bit size */ 129*40467Sbill unsigned ssd_gran:1 ; /* limit granularity (byte/page units)*/ 130*40467Sbill }; 131*40467Sbill 132*40467Sbill extern ssdtosd() ; /* to decode a ssd */ 133*40467Sbill extern sdtossd() ; /* to encode a sd */ 134*40467Sbill 135*40467Sbill /* 136*40467Sbill * region descriptors, used to load gdt/idt tables before segments yet exist 137*40467Sbill */ 138*40467Sbill struct region_descriptor { 139*40467Sbill unsigned rd_limit:16 ; /* segment extent */ 140*40467Sbill char *rd_base; /* base address */ 141*40467Sbill }; 142*40467Sbill 143