53 lines
1.4 KiB
C
53 lines
1.4 KiB
C
#include <stdio.h>
|
|
|
|
#include <gdt.h>
|
|
#include <drivers/gdt_ec.h>
|
|
|
|
#define GDT_ENTRIES 5
|
|
uint64_t gdt[GDT_ENTRIES];
|
|
|
|
struct {
|
|
uint16_t limit;
|
|
uint32_t base;
|
|
} __attribute__((packed)) gp;
|
|
|
|
|
|
extern void gdt_flush(uint32_t);
|
|
|
|
void gdt_install(bool prnt_gdt)
|
|
{
|
|
create_descriptor(0, 0, 0, 0, prnt_gdt); // Null
|
|
create_descriptor(1, 0, 0x000FFFFF, GDT_CODE_PL0, prnt_gdt); // Kernel code
|
|
create_descriptor(2, 0, 0x000FFFFF, GDT_DATA_PL0, prnt_gdt); // Kernel data
|
|
create_descriptor(3, 0, 0x000FFFFF, GDT_CODE_PL3, prnt_gdt); // User code
|
|
create_descriptor(4, 0, 0x000FFFFF, GDT_DATA_PL3, prnt_gdt); // User data
|
|
|
|
gp.limit = sizeof(gdt) - 1;
|
|
gp.base = (uint32_t)&gdt;
|
|
|
|
gdt_flush((uint32_t)&gp);
|
|
}
|
|
|
|
void create_descriptor(int index, uint32_t base, uint32_t limit, uint16_t flag, bool prnt_gdt)
|
|
{
|
|
uint64_t descriptor;
|
|
|
|
descriptor = limit & 0x000F0000; // limit bits 19:16
|
|
descriptor |= (flag << 8) & 0x00F0FF00; // flags and access
|
|
descriptor |= (base >> 16) & 0x000000FF; // base bits 23:16
|
|
descriptor |= base & 0xFF000000; // base bits 31:24
|
|
|
|
descriptor <<= 32;
|
|
|
|
descriptor |= ((uint64_t)base << 16); // base bits 15:0
|
|
descriptor |= (limit & 0x0000FFFF); // limit bits 15:0
|
|
|
|
gdt[index] = descriptor;
|
|
|
|
if (prnt_gdt)
|
|
{
|
|
printf("GDT[%d] = 0x%llX\n", index, descriptor);
|
|
}
|
|
}
|
|
|