42_KFS/headers/gdt.h
0x35c 9855669662 fix: gdt init no longer crashes
WIP: change page directory and stuff so the memory can work properly
2024-10-14 23:36:41 +02:00

42 lines
1.5 KiB
C

#pragma once
#include <stdint.h>
#define GDT_ADDRESS 0xC0105040
#define GDT_SIZE 7
// https://wiki.osdev.org/Global_Descriptor_Table#GDTR
struct gdt_descriptor {
uint16_t size;
uint32_t base;
} __attribute__((packed));
void init_gdt();
#define GDT_FLAG_64BIT_MODE 0b0010
#define GDT_FLAG_32BIT_MODE 0b0100
#define GDT_FLAG_PAGE_MODE 0b1000
#define GDT_FLAG_BYTE_MODE 0b1000
#define GDT_ACCESS_P_VALID 0b10000000
#define GDT_ACCESS_DPL_KERNEL_MODE 0b00000000
#define GDT_ACCESS_DPL_USER_MODE 0b01100000
#define GDT_ACCESS_S_CODE_OR_DATA 0b00010000
#define GDT_ACCESS_S_SYSTEM_SEGMENT 0b00010000
#define GDT_ACCESS_E_EXECUTABLE 0b00001000
#define GDT_ACCESS_E_NOT_EXECUTABLE 0b00000000
#define GDT_ACCESS_DC_CONFORM 0b00000100 // TODO UNDERSTAND THIS BIT
#define GDT_ACCESS_DC_NOT_CONFORM 0b00000000
#define GDT_ACCESS_RW_READABLE_FOR_CODE_WRITABLE_FOR_DATA 0b00000010
#define GDT_ACCESS_A_ACCESSED 0b00000001
#define GDT_ACCESS_A_NOT_ACCESSED 0b00000000
extern uint8_t gdt_entries[GDT_SIZE * 8];
#define GDT_OFFSET_KERNEL_CODE 0x08
#define GDT_OFFSET_KERNEL_DATA 0x10
#define GDT_OFFSET_KERNEL_STACK 0x18
#define GDT_OFFSET_USER_CODE 0x20
#define GDT_OFFSET_USER_DATA 0x28
#define GDT_OFFSET_USER_STACK 0x30