54 lines
1.2 KiB
C
54 lines
1.2 KiB
C
#include <kernel/x86/gdt.h>
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#include <stdint.h>
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#include <stdio.h>
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#ifdef __TESTING__
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#include <kernel/_kernel.h>
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#endif
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uint64_t gdt[GDT_SIZE];
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uint64_t create_descriptor(uint32_t base, uint32_t limit, uint16_t flag)
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{
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uint64_t descriptor;
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descriptor = limit & 0x000F0000;
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descriptor |= (flag << 8) & 0x00F0FF00;
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descriptor |= (base >> 16) & 0x000000FF;
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descriptor |= base & 0xFF000000;
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descriptor <<= 32;
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descriptor |= base << 16;
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descriptor |= limit & 0x0000FFFF;
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return descriptor;
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}
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void gdt_init(void)
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{
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#ifdef __TESTING__
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kinfo("Initializing the GDT");
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#endif
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gdt[0] = create_descriptor(0, 0, 0); // null
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gdt[1] = create_descriptor(0, 0x000FFFFF, (GDT_CODE_PL0)); // kernel code
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gdt[2] = create_descriptor(0, 0x000FFFFF, (GDT_DATA_PL0)); // kernel data
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gdt[3] = create_descriptor(0, 0x000FFFFF, (GDT_CODE_PL3)); // user code
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gdt[4] = create_descriptor(0, 0x000FFFFF, (GDT_DATA_PL3)); // user data
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setGdt((sizeof(uint64_t) * GDT_SIZE) - 1, &(gdt[0])); // limit, base
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reloadSegments();
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#ifdef __TESTING__
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kinfo("Initialized the GDT");
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dump_gdt();
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#endif
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}
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void dump_gdt(void)
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{
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for (int i = 0; i < GDT_SIZE; i++) {
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printf("GDT_ENTRY %d: %1 | %2\n", i, gdt[i], gdt[i]);
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}
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}
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