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95 lines
4.1 KiB
C
95 lines
4.1 KiB
C
//----------------------------------------------------------------------------//
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// OS on Kaleid //
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// //
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// Desc: GDT related functions //
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// //
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// //
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// Copyright © 2018-2021 The OS/K Team //
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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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#include <mm/gdt.h>
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#include <mm/paging.h>
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#include <init/boot.h>
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GdtPtr_t gdtPtr;
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GdtEntry_t gdt[7] __attribute__((__aligned__(KPAGESIZE)));
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TssDescriptor_t tssDesc __attribute__((__aligned__(KPAGESIZE)));
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Tss_t tss __attribute__((__aligned__(KPAGESIZE)));
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void MmInitGdt(void)
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{
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ushort tssOffset = (ushort)((ulong)(&gdt[5]) - (ulong)(&gdt[0]));
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gdtPtr.base = (ulong)&gdt[0];
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gdtPtr.limit = sizeof(gdt) - 1;
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memzero((void *)&gdt[0], sizeof(gdt));
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memzero((void *)&tssDesc, sizeof(tssDesc));
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memzero((void *)&tss, sizeof(tss));
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// Kernel codeseg
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gdt[1].lowLimit = 0x0;
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gdt[1].access = 0x9A;
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gdt[1].flags = 0x20;
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// Kernel dataseg
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gdt[2].lowLimit = 0x0;
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gdt[2].access = 0x92;
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gdt[2].flags = 0x00;
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// User dataseg
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gdt[3].lowLimit = 0x0;
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gdt[3].access = 0xF2;
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gdt[3].flags = 0x20;
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// User codeseg
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gdt[4].lowLimit = 0x0;
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gdt[4].access = 0xFA;
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gdt[4].flags = 0x20;
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tssDesc.access = 0x89;
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tssDesc.flags = 0x40;
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tssDesc.lowBase = (ulong)&tss & 0xFFFF;
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tssDesc.middleBase = ((ulong)&tss >> 16) & 0xFF;
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tssDesc.highBase = ((ulong)&tss >> 24) & 0xFF;
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tssDesc.veryHighBase = ((ulong)&tss >> 32) & 0xFFFFFFFF;
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tssDesc.lowLimit = sizeof(tss);
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tss.ist1 = (ulong)memalign(4*MB, 4*KB) + 4*MB; // ISR RESCUE STACK
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tss.ist2 = (ulong)memalign(4*MB, 4*KB) + 4*MB; // ISR STACK
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tss.ist3 = (ulong)memalign(4*MB, 4*KB) + 4*MB; // ISR STACK
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tss.rsp0 = (ulong)memalign(4*MB, 4*KB) + 4*MB; // Another Stack
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tss.iomap_base = sizeof(tss);
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memmove(&gdt[5], &tssDesc, sizeof(TssDescriptor_t));
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DebugLog("GDT & TSS initialized\n");
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DebugLog("Null descriptor : %#p\n", &gdt[0]);
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DebugLog("Kernel code descriptor : %#p\n", &gdt[1]);
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DebugLog("Kernel data descriptor : %#p\n", &gdt[2]);
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DebugLog("User data descriptor : %#p\n", &gdt[3]);
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DebugLog("User code descriptor : %#p\n", &gdt[4]);
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DebugLog("tss : %#p\n", &gdt[5]);
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DebugLog("ist1 : %#p\n", tss.ist1);
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DebugLog("ist2 : %#p\n", tss.ist2);
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DebugLog("ist3 : %#p\n", tss.ist3);
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DebugLog("rsp0 : %#p\n", tss.ist1);
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MmLoadGdt(&gdtPtr, tssOffset);
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}
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