| 1 | ;
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| 2 | ; SEGMENTS.ASM -- Manage segments
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| 3 | ;
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| 4 | ; Copyright (c) 1991-1999 by Eberhard Mattes
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| 5 | ;
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| 6 | ; This file is part of emx.
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| 7 | ;
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| 8 | ; emx is free software; you can redistribute it and/or modify it
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| 9 | ; under the terms of the GNU General Public License as published by
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| 10 | ; the Free Software Foundation; either version 2, or (at your option)
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| 11 | ; any later version.
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| 12 | ;
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| 13 | ; emx is distributed in the hope that it will be useful,
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| 14 | ; but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 15 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 16 | ; GNU General Public License for more details.
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| 17 | ;
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| 18 | ; You should have received a copy of the GNU General Public License
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| 19 | ; along with emx; see the file COPYING. If not, write to
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| 20 | ; the Free Software Foundation, 59 Temple Place - Suite 330,
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| 21 | ; Boston, MA 02111-1307, USA.
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| 22 | ;
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| 23 | ; See emx.asm for a special exception.
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| 24 | ;
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| 25 |
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| 26 | __SEGMENTS = 1
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| 27 |
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| 28 | INCLUDE EMX.INC
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| 29 | INCLUDE TABLES.INC
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| 30 | INCLUDE MISC.INC
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| 31 | INCLUDE PAGING.INC
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| 32 | INCLUDE SEGMENTS.INC
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| 33 | INCLUDE SIGNAL.INC ; Required by PROCESS.INC
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| 34 | INCLUDE PROCESS.INC
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| 35 |
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| 36 | PUBLIC NEW_TSS, G_PHYS_BASE
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| 37 | PUBLIC CREATE_SEG, SEG_SIZE, SEG_BASE, SEG_ATTR, GET_BASE
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| 38 | PUBLIC NULL_SEG, GET_LIN, GET_DESC, SV_SEGMENT, ADD_PAGES
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| 39 | PUBLIC ACCESS_LOWMEM, MAP_PHYS
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| 40 | PUBLIC INIT_DESC, RM_SEG_BASE, RM_SEG_SIZE, INIT_TSS
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| 41 |
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| 42 | SV_DATA SEGMENT
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| 43 |
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| 44 | ;
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| 45 | ; Base address of G_PHYS_SEL (see also G_PHYS_DESC)
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| 46 | ;
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| 47 | G_PHYS_BASE DD 0
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| 48 | ;
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| 49 | ; New TSS (with I/O bitmap) active
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| 50 | ;
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| 51 | NEW_TSS DB FALSE ; Initially not active
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| 52 |
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| 53 | SV_DATA ENDS
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| 54 |
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| 55 |
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| 56 | SV_CODE SEGMENT
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| 57 |
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| 58 | ASSUME CS:SV_CODE, DS:NOTHING
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| 59 |
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| 60 |
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| 61 | ;
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| 62 | ; Create a segment (make GDT/LDT entry)
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| 63 | ;
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| 64 | ; In: SI Pointer to GDT/LDT entry
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| 65 | ; AX Segment attributes (A_CODE32, A_DATA32, DPL_0, ..., DPL_3)
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| 66 | ; EBX Base address of segment
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| 67 | ; ECX Size of segment (limit+1)
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| 68 | ;
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| 69 | ASSUME DS:NOTHING
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| 70 |
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| 71 | CREATE_SEG PROC NEAR
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| 72 | CALL SEG_ATTR
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| 73 | CALL SEG_BASE
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| 74 | CALL SEG_SIZE
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| 75 | RET
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| 76 | CREATE_SEG ENDP
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| 77 |
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| 78 |
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| 79 | ;
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| 80 | ; Set the type/attributes of a segment
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| 81 | ;
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| 82 | ; In: DS:SI Pointer to descriptor
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| 83 | ; AX Type / attributes (A_CODE32, A_DATA32, DPL_0, ..., DPL_3)
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| 84 | ;
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| 85 | SEG_ATTR PROC NEAR
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| 86 | AND WORD PTR [SI+5], 0CF00H ; Clear all but G, B|D, limit
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| 87 | OR [SI+5], AX ; Set segment type/attributes
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| 88 | RET
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| 89 | SEG_ATTR ENDP
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| 90 |
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| 91 |
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| 92 | ;
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| 93 | ; Set the base address of a segment
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| 94 | ;
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| 95 | ; In: DS:SI Pointer to GDT entry
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| 96 | ; EBX Base address of segment
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| 97 | ;
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| 98 | ASSUME SI:PTR DESCRIPTOR
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| 99 | SEG_BASE PROC NEAR
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| 100 | PUSH EBX
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| 101 | MOV [SI].BASE_0_15, BX ; Base 0..15
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| 102 | SHR EBX, 16
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| 103 | MOV [SI].BASE_16_23, BL ; Base 16..23
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| 104 | MOV [SI].BASE_24_31, BH ; Base 24..31
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| 105 | POP EBX
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| 106 | RET
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| 107 | ASSUME SI:NOTHING
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| 108 | SEG_BASE ENDP
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| 109 |
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| 110 |
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| 111 | ;
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| 112 | ; Set the size of a segment
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| 113 | ;
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| 114 | ; In: DS:SI Pointer to GDT entry (already contains access & other info)
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| 115 | ; ECX Size of segment (limit+1)
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| 116 | ;
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| 117 | ASSUME SI:PTR DESCRIPTOR
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| 118 | SEG_SIZE PROC NEAR
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| 119 | PUSH ECX
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| 120 | AND [SI].GRAN, 70H ; Keep B|0|AVL, clear G|limit
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| 121 | CMP ECX, 1 SHL 20 ; Byte granular?
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| 122 | JA SHORT SS_BIG ; No -> page granular
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| 123 | DEC ECX ; ECX := limit (byte granular)
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| 124 | MOV [SI].LIMIT_0_15, CX ; Limit 0..15
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| 125 | SHR ECX, 16
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| 126 | OR [SI].GRAN, CL ; Limit 16..19
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| 127 | JMP SHORT SS_RET
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| 128 |
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| 129 | SS_BIG: ADD ECX, 0FFFH ; Round up
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| 130 | SHR ECX, 12 ; Convert to number of pages
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| 131 | DEC ECX ; ECX := limit (page granular)
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| 132 | MOV [SI].LIMIT_0_15, CX ; Limit 0..15
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| 133 | SHR ECX, 16
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| 134 | OR CL, 80H ; Set G
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| 135 | OR [SI].GRAN, CL ; Limit 16..19
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| 136 | SS_RET: POP ECX
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| 137 | RET
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| 138 | ASSUME SI:NOTHING
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| 139 | SEG_SIZE ENDP
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| 140 |
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| 141 |
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| 142 | ;
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| 143 | ; Get the base address of a segment
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| 144 | ;
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| 145 | ; In: DS:SI Pointer to GDT entry
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| 146 | ;
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| 147 | ; Out: EBX Base address of segment
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| 148 | ;
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| 149 | ASSUME SI:PTR DESCRIPTOR
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| 150 | GET_BASE PROC NEAR
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| 151 | MOV BL, [SI].BASE_16_23 ; Base 16..23
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| 152 | MOV BH, [SI].BASE_24_31 ; Base 24..31
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| 153 | SHL EBX, 16
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| 154 | MOV BX, [SI].BASE_0_15 ; Base 0..15
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| 155 | RET
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| 156 | ASSUME SI:NOTHING
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| 157 | GET_BASE ENDP
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| 158 |
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| 159 | ;
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| 160 | ; Convert virtual address to linear address
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| 161 | ;
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| 162 | ; In: AX Selector
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| 163 | ; EBX Offset
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| 164 | ; LDTR Local descriptor table
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| 165 | ;
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| 166 | ; Out: EBX Linear address
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| 167 | ; CY Error
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| 168 | ;
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| 169 | ASSUME DS:SV_DATA
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| 170 | GET_LIN PROC NEAR
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| 171 | PUSH EAX
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| 172 | PUSH ESI
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| 173 | .386P
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| 174 | SLDT SI
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| 175 | .386
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| 176 | CALL GET_DESC
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| 177 | MOV EAX, EBX
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| 178 | CALL GET_BASE
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| 179 | ADD EBX, EAX
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| 180 | CLC
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| 181 | POP ESI
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| 182 | POP EAX
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| 183 | RET
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| 184 | GET_LIN ENDP
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| 185 |
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| 186 | ;
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| 187 | ; Get LDT/GDT entry
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| 188 | ;
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| 189 | ; In: AX Selector
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| 190 | ; SI Local descriptor table (selector)
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| 191 | ;
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| 192 | ; Out: SI Pointer to table entry
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| 193 | ;
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| 194 | ASSUME DS:SV_DATA
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| 195 | GET_DESC PROC NEAR
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| 196 | PUSH AX
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| 197 | TEST AX, 04H ; GDT?
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| 198 | JZ SHORT GDES_1 ; Yes ->
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| 199 | AND SI, NOT 07H
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| 200 | SUB SI, G_LDT_SEL
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| 201 | IMUL SI, LDT_ENTRIES
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| 202 | LEA SI, LDTS[SI]
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| 203 | JMP SHORT GDES_2
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| 204 | GDES_1: LEA SI, GDT
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| 205 | GDES_2: AND AX, NOT 07H
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| 206 | ADD SI, AX
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| 207 | POP AX
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| 208 | RET
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| 209 | GET_DESC ENDP
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| 210 |
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| 211 | ;
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| 212 | ; Create a null segment (make GDT/LDT entry)
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| 213 | ;
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| 214 | ; In: DS:SI Pointer to GDT/LDT entry
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| 215 | ;
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| 216 | ASSUME DS:NOTHING
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| 217 | NULL_SEG PROC NEAR
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| 218 | MOV DWORD PTR [SI+0], 0
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| 219 | MOV DWORD PTR [SI+4], 0
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| 220 | RET
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| 221 | NULL_SEG ENDP
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| 222 |
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| 223 |
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| 224 | ;
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| 225 | ; Create supervisor data segment (not swappable)
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| 226 | ;
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| 227 | ; In: ECX Size (bytes)
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| 228 | ; DS:SI Pointer to GDT entry
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| 229 | ;
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| 230 | ; Out: CY Out of memory
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| 231 | ;
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| 232 | ; Note: No physical memory is allocated for the pages, so the pages must
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| 233 | ; be present if accessed from within the page fault handler (to avoid
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| 234 | ; recursion)
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| 235 | ;
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| 236 | ASSUME DS:SV_DATA
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| 237 | SV_SEGMENT PROC NEAR
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| 238 | PUSH EAX
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| 239 | PUSH EBX
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| 240 | PUSH ECX
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| 241 | MOV AL, PIDX_SV
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| 242 | CALL ALLOC_PAGES ; Get linear addresses
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| 243 | CALL INIT_PAGES ; Create page tables
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| 244 | JC SHORT SVS_RET ; Out of memory -> return
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| 245 | MOV EBX, PAGE_LOCKED ; Create locked pages
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| 246 | MOV EDX, PIDX_SV OR SRC_ZERO
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| 247 | CALL SET_PAGES
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| 248 | MOV EBX, EAX ; Linear address to EBX
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| 249 | POP ECX ; Number of bytes
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| 250 | PUSH ECX
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| 251 | MOV AX, A_DATA32 OR DPL_0 ; Supervisor data segment
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| 252 | CALL CREATE_SEG ; Create segment descriptor
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| 253 | SVS_RET: POP ECX
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| 254 | POP EBX
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| 255 | POP EAX
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| 256 | RET
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| 257 | SV_SEGMENT ENDP
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| 258 |
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| 259 | ;
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| 260 | ; Allocate, initialize and switch to new TSS.
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| 261 | ;
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| 262 | ; If there isn't enough memory, NEW_TSS stays FALSE.
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| 263 | ;
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| 264 | ASSUME DS:SV_DATA
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| 265 | INIT_TSS PROC NEAR
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| 266 | ;
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| 267 | ; Allocate memory
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| 268 | ;
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| 269 | MOV ECX, SIZE TSS_STRUC + 2001H
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| 270 | LEA SI, G_TMP1_DESC ; Use temporary descriptor
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| 271 | CALL SV_SEGMENT ; Create supervisor segment
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| 272 | JC SHORT IT_RET ; Out of memory -> done
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| 273 | ;
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| 274 | ; Copy initial TSS to new segment
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| 275 | ;
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| 276 | PUSH DS ; Save DS
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| 277 | MOV AX, G_TSS_MEM_SEL
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| 278 | MOV DS, AX
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| 279 | MOV AX, G_TMP1_SEL
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| 280 | MOV ES, AX
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| 281 | XOR SI, SI
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| 282 | XOR DI, DI
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| 283 | MOV CX, SIZE TSS_STRUC
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| 284 | REP MOVSB
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| 285 | ;
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| 286 | ; Initialize I/O bitmap (all 64K ports disabled)
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| 287 | ;
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| 288 | MOV AX, 0FFH
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| 289 | MOV CX, 2001H
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| 290 | REP STOSB
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| 291 | POP DS ; Restore DS
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| 292 | ;
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| 293 | ; Copy to G_TSS_MEM_SEL descriptor
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| 294 | ;
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| 295 | MOV_ES_DS ; ES := DS
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| 296 | LEA SI, G_TMP1_DESC
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| 297 | LEA DI, G_TSS_MEM_DESC
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| 298 | MOVSD
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| 299 | MOVSD
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| 300 | ;
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| 301 | ; Copy to G_TSS_SEL descriptor
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| 302 | ;
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| 303 | CLI ; Disable interrupts
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| 304 | LEA SI, G_TMP1_DESC
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| 305 | LEA DI, G_TSS_DESC
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| 306 | MOVSD
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| 307 | MOVSD
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| 308 | LEA SI, G_TSS_DESC
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| 309 | MOV AX, A_TSS ; Turn it into a TSS desciptor
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| 310 | CALL SEG_ATTR
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| 311 | ;
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| 312 | ; Switch to new TSS
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| 313 | ;
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| 314 | AND TSS_BUSY, NOT 2
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| 315 | MOV AX, G_TSS_SEL
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| 316 | .386P
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| 317 | LTR AX
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| 318 | .386
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| 319 | STI ; Enable interrupts
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| 320 | MOV NEW_TSS, NOT FALSE ; New TSS active
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| 321 | IT_RET: RET
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| 322 | INIT_TSS ENDP
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| 323 |
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| 324 | ;
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| 325 | ; Add some pages of memory to a process. The pages will be added at the
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| 326 | ; end of the data segment, above the stack.
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| 327 | ;
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| 328 | ; In: DI Pointer to process table entry
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| 329 | ; ECX Number of pages
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| 330 | ;
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| 331 | ; Out: EAX Address in process space of the memory (or 0 on failure)
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| 332 | ;
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| 333 | ASSUME DS:SV_DATA
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| 334 | ADD_PAGES PROC NEAR
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| 335 | ASSUME DI:PTR PROCESS
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| 336 | PUSH SI
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| 337 | MOV EAX, [DI].P_DSEG_SIZE
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| 338 | ADD EAX, 1000H ; One empty page
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| 339 | PUSH EAX ; Save the return value
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| 340 | SHL ECX, 12 ; Compute number of bytes
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| 341 | ADD EAX, ECX ; Adjust end address
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| 342 | JC SHORT AP_FAIL ; Overflow -> fail
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| 343 | CMP EAX, [DI].P_LIN_SIZE ; Beyond end of address space?
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| 344 | JA SHORT AP_FAIL ; Yes -> fail
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| 345 | MOV EDX, EAX ; New data segment size
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| 346 | POP EAX ; Address of new pages
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| 347 | PUSH EAX
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| 348 | PUSH EDX
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| 349 | ADD EAX, [DI].P_LINEAR ; Compute linear address
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| 350 | SHR ECX, 12 ; Number of pages
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| 351 | MOV EBX, PAGE_WRITE OR PAGE_USER
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| 352 | MOV EDX, SRC_NONE
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| 353 | TEST [DI].P_FLAGS, PF_DONT_ZERO
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| 354 | JNZ SHORT AP_1
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| 355 | MOV EDX, SRC_ZERO
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| 356 | AP_1: MOV DL, [DI].P_PIDX
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| 357 | CALL SET_COMMIT ; Set PAGE_ALLOC bit
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| 358 | CALL SET_PAGES
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| 359 | POP EAX ; New data segment size
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| 360 | JC SHORT AP_FAIL
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| 361 | MOV [DI].P_DSEG_SIZE, EAX ; Update data segment size
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| 362 | MOV ECX, [DI].P_DSEG_SIZE
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| 363 | MOV SI, [DI].P_LDT_PTR
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| 364 | ADD SI, L_DATA_SEL AND NOT 07H
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| 365 | CALL SEG_SIZE
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| 366 | POP EAX
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| 367 | POP SI
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| 368 | RET
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| 369 |
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| 370 | AP_FAIL: POP EAX
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| 371 | POP SI
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| 372 | XOR EAX, EAX ; Return 0
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| 373 | RET
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| 374 | ASSUME DI:NOTHING
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| 375 | ADD_PAGES ENDP
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| 376 |
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| 377 |
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| 378 | ;
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| 379 | ; Map pages into the address space of a process
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| 380 | ;
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| 381 | ; In: DI Pointer to process table entry
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| 382 | ; EBX Physical address
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| 383 | ; ECX Number of pages
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| 384 | ;
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| 385 | ; Out: EAX Adress in process space (0 if no space)
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| 386 | ;
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| 387 | ASSUME DS:SV_DATA
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| 388 | ASSUME DI:PTR PROCESS
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| 389 | MAP_PHYS PROC NEAR
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| 390 | MOV EAX, [DI].P_DSEG_SIZE
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| 391 | ADD EAX, 1000H
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| 392 | PUSH EAX
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| 393 | MOV EDX, ECX
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| 394 | SHL EDX, 12
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| 395 | ADD EAX, EDX
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| 396 | JC SHORT MP_FAIL
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| 397 | CMP EAX, [DI].P_LIN_SIZE
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| 398 | JA SHORT MP_FAIL
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| 399 | MOV [DI].P_DSEG_SIZE, EAX
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| 400 | SUB EAX, EDX
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| 401 | ADD EAX, [DI].P_LINEAR
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| 402 | MOV DL, [DI].P_PIDX
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| 403 | TEST EBX, NOT 0FFFH ; Is the address = 0?
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| 404 | JNZ SHORT MP_MORE ; No -> continue
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| 405 | PUSH ECX
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| 406 | MOV ECX, 1 ; Set one page table entry
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| 407 | CALL SET_PAGES ; This is required because
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| 408 | POP ECX ; SET_PAGES doesn't increment
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| 409 | DEC ECX ; the address if it is 0
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| 410 | JZ SHORT MP_DONE
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| 411 | ADD EAX, 1000H
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| 412 | ADD EBX, 1000H
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| 413 | MP_MORE: CALL SET_PAGES
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| 414 | MP_DONE: MOV ECX, [DI].P_DSEG_SIZE
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| 415 | MOV SI, [DI].P_LDT_PTR
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| 416 | ADD SI, L_DATA_SEL AND NOT 07H
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| 417 | CALL SEG_SIZE
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| 418 | POP EAX
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| 419 | RET
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| 420 |
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| 421 | MP_FAIL: POP EAX
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| 422 | XOR EAX, EAX
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| 423 | RET
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| 424 | ASSUME DI:NOTHING
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| 425 | MAP_PHYS ENDP
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| 426 |
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| 427 |
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| 428 | ;
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| 429 | ; Convert real-mode pointer to protected-mode pointer
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| 430 | ;
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| 431 | ; In: EAX Real-mode Segment:Offset
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| 432 | ;
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| 433 | ; Out: EBX Offset into G_LOWMEM_SEL segment
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|---|
| 434 | ; EAX Modified
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|---|
| 435 | ;
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|---|
| 436 | ACCESS_LOWMEM PROC NEAR
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|---|
| 437 | ROL EAX, 16 ; EAX = offset:segment
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|---|
| 438 | MOVZX EBX, AX ; EBX = segment
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|---|
| 439 | SHL EBX, 4 ; EBX = base address of segment
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|---|
| 440 | SHR EAX, 16 ; EAX = offset
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|---|
| 441 | ADD EBX, EAX
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|---|
| 442 | RET
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|---|
| 443 | ACCESS_LOWMEM ENDP
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|---|
| 444 |
|
|---|
| 445 | SV_CODE ENDS
|
|---|
| 446 |
|
|---|
| 447 |
|
|---|
| 448 |
|
|---|
| 449 | INIT_CODE SEGMENT
|
|---|
| 450 |
|
|---|
| 451 | ASSUME CS:INIT_CODE, DS:NOTHING
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|---|
| 452 |
|
|---|
| 453 | ;
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|---|
| 454 | ; Convert the base field of a GDT entry. It already contains the
|
|---|
| 455 | ; offset into the real-mode segment given in AX.
|
|---|
| 456 | ;
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|---|
| 457 | ; In: AX Real-mode segment
|
|---|
| 458 | ; DI Pointer to descriptor table entry (SV_DATA)
|
|---|
| 459 | ;
|
|---|
| 460 | ASSUME DS:SV_DATA
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|---|
| 461 | ASSUME DI:PTR DESCRIPTOR
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|---|
| 462 | INIT_DESC PROC NEAR
|
|---|
| 463 | PUSH EAX
|
|---|
| 464 | PUSH EDX
|
|---|
| 465 | MOVZX EAX, AX
|
|---|
| 466 | SHL EAX, 4
|
|---|
| 467 | MOVZX EDX, [DI].BASE_0_15 ; Get real-mode offset
|
|---|
| 468 | ADD EAX, EDX
|
|---|
| 469 | CALL RM_SEG_BASE ; Set base address
|
|---|
| 470 | POP EDX
|
|---|
| 471 | POP EAX
|
|---|
| 472 | RET
|
|---|
| 473 | ASSUME DI:NOTHING
|
|---|
| 474 | INIT_DESC ENDP
|
|---|
| 475 |
|
|---|
| 476 |
|
|---|
| 477 |
|
|---|
| 478 | ;
|
|---|
| 479 | ; Set the base address of a segment (real-mode version)
|
|---|
| 480 | ;
|
|---|
| 481 | ; In: DS:DI Pointer to GDT entry
|
|---|
| 482 | ; EAX Base address of segment
|
|---|
| 483 | ;
|
|---|
| 484 | ASSUME DS:SV_DATA
|
|---|
| 485 | ASSUME DI:PTR DESCRIPTOR
|
|---|
| 486 | RM_SEG_BASE PROC NEAR
|
|---|
| 487 | PUSH EAX
|
|---|
| 488 | MOV [DI].BASE_0_15, AX ; Base 0..15
|
|---|
| 489 | SHR EAX, 16
|
|---|
| 490 | MOV [DI].BASE_16_23, AL ; Base 16..23
|
|---|
| 491 | MOV [DI].BASE_24_31, AH ; Base 24..31
|
|---|
| 492 | POP EAX
|
|---|
| 493 | RET
|
|---|
| 494 | ASSUME DI:NOTHING
|
|---|
| 495 | RM_SEG_BASE ENDP
|
|---|
| 496 |
|
|---|
| 497 |
|
|---|
| 498 | ;
|
|---|
| 499 | ; Set the size of a segment (real-mode version)
|
|---|
| 500 | ;
|
|---|
| 501 | ; In: DS:DI Pointer to GDT entry
|
|---|
| 502 | ; ECX Size of segment (limit+1)
|
|---|
| 503 | ;
|
|---|
| 504 | ASSUME DS:SV_DATA
|
|---|
| 505 | ASSUME DI:PTR DESCRIPTOR
|
|---|
| 506 | RM_SEG_SIZE PROC NEAR
|
|---|
| 507 | PUSH ECX
|
|---|
| 508 | AND [DI].GRAN, 70H ; Keep B|0|AVL, clear G|limit
|
|---|
| 509 | CMP ECX, 1 SHL 20 ; Byte granular?
|
|---|
| 510 | JA SHORT RSS_BIG ; No -> page granular
|
|---|
| 511 | DEC ECX ; ECX := limit (byte granular)
|
|---|
| 512 | MOV [DI].LIMIT_0_15, CX ; Limit 0..15
|
|---|
| 513 | SHR ECX, 16
|
|---|
| 514 | OR [DI].GRAN, CL ; Limit 16..19
|
|---|
| 515 | JMP SHORT RSS_RET
|
|---|
| 516 |
|
|---|
| 517 | RSS_BIG: ADD ECX, 0FFFH ; Round up
|
|---|
| 518 | SHR ECX, 12 ; Convert to number of pages
|
|---|
| 519 | DEC ECX ; ECX := limit (page granular)
|
|---|
| 520 | MOV [DI].LIMIT_0_15, CX ; Limit 0..15
|
|---|
| 521 | SHR ECX, 16
|
|---|
| 522 | OR CL, 80H ; Set G
|
|---|
| 523 | OR [DI].GRAN, CL ; Limit 16..19
|
|---|
| 524 | RSS_RET: POP ECX
|
|---|
| 525 | RET
|
|---|
| 526 | ASSUME DI:NOTHING
|
|---|
| 527 | RM_SEG_SIZE ENDP
|
|---|
| 528 |
|
|---|
| 529 |
|
|---|
| 530 | INIT_CODE ENDS
|
|---|
| 531 |
|
|---|
| 532 | END
|
|---|
