os-k/kaleid/kernel/mm/gdt.c

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//----------------------------------------------------------------------------//
// GNU GPL OS/K //
// //
// Desc: Mapping and checking memory related functions //
// //
// //
// Copyright © 2018-2019 The OS/K Team //
// //
// This file is part of OS/K. //
// //
// OS/K is free software: you can redistribute it and/or modify //
// it under the terms of the GNU General Public License as published by //
// the Free Software Foundation, either version 3 of the License, or //
// any later version. //
// //
// OS/K is distributed in the hope that it will be useful, //
// but WITHOUT ANY WARRANTY//without even the implied warranty of //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
// GNU General Public License for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with OS/K. If not, see <https://www.gnu.org/licenses/>. //
//----------------------------------------------------------------------------//
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#include <mm/mm.h>
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GdtEntry_t gdtEntries[5] = { 0 };
TssEntry_t tssEntry = { 0 };
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GdtPtr_t gdtPtr;
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static void SetGdtEntry(int index, uint base, uint limit, uchar access)
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{
gdtEntries[index].lowBase = (base & 0xFFFF);
gdtEntries[index].middleBase = (base >> 16) & 0xFF;
gdtEntries[index].highBase = (base >> 24) & 0xFF;
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gdtEntries[index].lowLimit = (limit & 0xFFFF);
gdtEntries[index].granularity = (limit >> 16) & 0x0F;
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gdtEntries[index].granularity |= 0xA0;
// 0x10 is system
// 0x80 is present
gdtEntries[index].access = access | 0x10 | 0x80;
}
static void SetTssEntry(uchar index, ulong base, ulong limit)
{
TssDescriptor_t tssDesc = { 0 };
tssDesc.limitLow = limit & 0xffff;
tssDesc.size = (limit >> 16) & 0xf;
tssDesc.base00 = base & 0xffff;
tssDesc.base16 = (base >> 16) & 0xff;
tssDesc.base24 = (base >> 24) & 0xff;
tssDesc.base32 = (base >> 32) & 0xffffffff;
tssDesc.reserved = 0;
tssDesc.access = 0x01 | 0x08 | 0x10 | 0x80;
memmove(&gdtEntries[index], &tssDesc, sizeof(TssDescriptor_t));
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}
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void MmInitGdt(void)
{
gdtPtr.limit = (sizeof(GdtEntry_t) * 5) - 1;
gdtPtr.base = (uint)(ullong)&gdtEntries;
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MmStoreGdt();
/* SetGdtEntry(1, 0x0, 0xfffff, 0x02 | 0x08); */
/* tssEntry.ioMapOffset = sizeof(TssEntry_t); */
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/* SetTssEntry(2, (ulong)&tssEntry, sizeof(TssEntry_t)); */
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/* MmLoadGdt(0x8, 0x0, 2 << 3); */
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}