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[MEMORY] GDT

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This commit is contained in:
Thomas Lovén 2017-01-26 09:02:33 +01:00
parent deb1f031ce
commit 1f06c0bcf1
4 changed files with 69 additions and 17 deletions
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25
kernel/arch/gdt.c Normal file
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@ -0,0 +1,25 @@
#include <gdt.h>
#include <stdint.h>
#include <debug.h>
uint64_t gdt[5];
struct gdtp_st gdt_p;
#define GDT gdt
#define GDTP gdt_p
void gdt_init()
{
GDT[0] = 0;
GDT[SEG_KCODE/8] = (uint64_t)(GDT_PRESENT | GDT_CODEDATA | GDT_WRITE | GDT_EXECUTE | GDT_64BIT);
GDT[SEG_KDATA/8] = (GDT_PRESENT | GDT_CODEDATA | GDT_WRITE);
GDT[SEG_UCODE/8] = (GDT_PRESENT | GDT_CODEDATA | GDT_WRITE | GDT_EXECUTE | GDT_64BIT | GDT_RING3);
GDT[SEG_UDATA/8] = (GDT_PRESENT | GDT_CODEDATA | GDT_WRITE | GDT_RING3);
GDTP.len = 5*8-1;
GDTP.addr = (uint64_t)&GDT[0];
load_gdt(&GDTP);
}

16
kernel/arch/registers.S
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@ -1,4 +1,5 @@
.intel_syntax noprefix
#include <gdt.h>
.global load_idt
load_idt:
@ -25,3 +26,18 @@ write_cr3:
read_cr4:
mov rax, cr4
ret
.global load_gdt
load_gdt:
lgdt [rdi]
mov ax, SEG_KDATA
mov ss, ax
mov ds, ax
mov es, ax
movabs rax, offset .load_gdt
pushq SEG_KCODE
push rax
retfq # perform long jump to SEG_KCODE:.load_gdt
.load_gdt:
ret

18
kernel/boot/kmain.c
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@ -2,6 +2,7 @@
#include <int.h>
#include <multiboot.h>
#include <mem.h>
#include <gdt.h>
int kmain(uint64_t multiboot_magic, void *multiboot_data)
{
@ -14,23 +15,8 @@ int kmain(uint64_t multiboot_magic, void *multiboot_data)
multiboot_init(multiboot_magic, P2V(multiboot_data));
vmm_init();
pmm_init();
gdt_init();
// We still need the GDT to be mapped in
extern void *BootGDT;
vmm_set_page(0, V2P(&BootGDT), V2P(&BootGDT), PAGE_PRESENT);
void *a = kmalloc(0x400);
void *b = kmalloc(0x200);
void *c = kmalloc(0x100);
kfree(b);
void *d = kmalloc(0x100);
(void)a;
(void)b;
(void)c;
(void)d;
heap_print();
debug_info("BOOT COMPLETE\n");
for(;;)asm("hlt");

27
kernel/include/gdt.h
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@ -1,12 +1,37 @@
#pragma once
#define SEG_KCODE 0x08
#define SEG_KDATA 0x10
#define SEG_UDATA 0x18
#define SEG_UCODE 0x20
#ifdef __ASSEMBLER__
#define GDT_WRITE (1<<41)
#define GDT_EXECUTE (1<<43)
#define GDT_CODEDATA (1<<44)
#define GDT_PRESENT (1<<47)
#define GDT_64BIT (1<<53)
#else
#define GDT_WRITE (1LL<<41)
#define GDT_EXECUTE (1LL<<43)
#define GDT_CODEDATA (1LL<<44)
#define GDT_PRESENT (1LL<<47)
#define GDT_64BIT (1LL<<53)
#define GDT_RING3 (3LL<<45)
#define GDT_TSS (9LL<<40)
#ifndef __ASSEMBLER__
#include <stdint.h>
extern uint64_t BootGDT;
struct gdtp_st
{
uint16_t len;
uint64_t addr;
uint16_t pad1;
uint32_t pad2;
}__attribute__((packed));
void load_gdt(struct gdtp_st *);
void gdt_init();
#endif