gdt.h

 
#ifndef KERNEL_ARCH_I686_GDT_H
#define KERNEL_ARCH_I686_GDT_H
 
#include <kernel/types.h>
 
#include <utils/compiler.h>
 
// Hard coded constant linear base 32-bits address for the TSS
#define GDT_TSS_BASE_ADDRESS 0x00000000UL
 
enum {
    GDT_ENTRY_NULL = 0,        
    GDT_ENTRY_KERNEL_CODE = 1, 
    GDT_ENTRY_KERNEL_DATA = 2, 
    GDT_ENTRY_USER_CODE = 3,   
    GDT_ENTRY_USER_DATA = 4,   
    GDT_ENTRY_TSS = 5
};
 
typedef struct gdtr gdtr;
struct PACKED gdtr {
    u16 size;
    u32 offset;
};
 
typedef struct gdt_descriptor {
    u32 base;
    u32 limit : 20;
    u8 access;
    u8 flags : 4;
} gdt_descriptor;
 
typedef struct PACKED tss {
    u16 link;
    u16 _reserved1;
    u32 esp0;
    u16 ss0;
    u16 _reserved2;
    u32 esp1;
    u16 ss1;
    u16 _reserved3;
    u32 esp2;
    u16 ss2;
    u16 _reserved4;
    u32 cr3;
    u32 eip;
    u32 eflags;
    u32 eax;
    u32 ecx;
    u32 edx;
    u32 ebx;
    u32 esp;
    u32 ebp;
    u32 esi;
    u32 edi;
    u16 es;
    u16 _reserved5;
    u16 cs;
    u16 _reserved6;
    u16 ss;
    u16 _reserved7;
    u16 ds;
    u16 _reserved8;
    u16 fs;
    u16 _reserved9;
    u16 gs;
    u16 _reserved10;
    u16 ldtr;
    u16 _reserved11;
    u16 _reserved12;
    u16 iopb;
    u32 ssp;
} tss_t;
 
typedef union {
    u16 raw;
    struct {
        u8 rpl : 2;
        u8 ti : 1;
        u16 index : 13;
    } PACKED;
} segment_selector;
 
void gdt_init(void);
 
void gdt_load_segment(gdt_descriptor, u16 index);
 
void gdt_log(void);
 
void gdt_set_esp0(u32);
 
#endif /* KERNEL_ARCH_I686_GDT_H */