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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
View File

@@ -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