2020-01-12 16:53:32 +01:00
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//----------------------------------------------------------------------------//
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// GNU GPL OS/K //
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// //
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// Desc: GDT related functions //
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// //
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// //
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2020-02-06 14:23:26 +01:00
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// Copyright © 2018-2020 The OS/K Team //
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2020-01-12 16:53:32 +01:00
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// //
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// This file is part of OS/K. //
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// //
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// OS/K is free software: you can redistribute it and/or modify //
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// it under the terms of the GNU General Public License as published by //
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// the Free Software Foundation, either version 3 of the License, or //
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// any later version. //
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// //
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// OS/K is distributed in the hope that it will be useful, //
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// but WITHOUT ANY WARRANTY//without even the implied warranty of //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
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// GNU General Public License for more details. //
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// //
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// You should have received a copy of the GNU General Public License //
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// along with OS/K. If not, see <https://www.gnu.org/licenses/>. //
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//----------------------------------------------------------------------------//
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#ifndef _KERNEL_H
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#include <kernel.h>
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#endif
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#ifndef _MM_GDT_H
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#define _MM_GDT_H
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//----------------------------------------------------------------------------//
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#define IOMAP_SIZE (8 * 1024)
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//----------------------------------------------------------------------------//
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// The gdt entry
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struct GdtEntry_t
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{
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ushort lowLimit; // lower 16 bits
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ushort lowBase; // lower 16 bits
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uchar middleBase; // next 8 bits
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uchar access; // determine what ring this segment can be used in
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uchar flags;
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uchar highBase; // last 8 bits
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} __attribute__((__packed__));
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struct TssDescriptor_t
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{
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ushort lowLimit;
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ushort lowBase;
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uchar middleBase;
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uchar access;
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uchar flags;
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uchar highBase;
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uint veryHighBase;
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uint reserved;
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} __attribute__ ((packed));
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struct Tss_t
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{
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uint reserved1;
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// Stack pointers (RSP) for privilege levels 0-2
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ulong rsp0;
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ulong rsp1;
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ulong rsp2;
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ulong reserved2;
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// Interrupt stack table pointers
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ulong ist1;
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ulong ist2;
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ulong ist3;
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ulong ist4;
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ulong ist5;
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ulong ist6;
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ulong ist7;
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ulong reserved3;
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ushort reserved4;
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// Offset to the I/O permission bit map from the 64-bit TSS base
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ushort iomap_base;
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uchar iomap[IOMAP_SIZE];
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} __attribute__ ((packed)) __attribute__((aligned(8)));
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// The gdt pointer
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struct GdtPtr_t
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{
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ushort limit; // upper 16 bits
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ulong base; // address of the first entry
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} __attribute__((__packed__));
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//----------------------------------------------------------------------------//
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//
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// Initializes the descriptor table
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//
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void MmInitGdt(void);
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//
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// Loads the descriptor table
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//
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extern void MmLoadGdt(GdtPtr_t *gdtPtr, ushort tssOffset);
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//
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// Stores the descriptor table
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//
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extern void MmStoreGdt(void);
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//----------------------------------------------------------------------------//
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#endif
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