Got GDT working

kernel/src/entry.s

@@ -17,20 +17,22 @@ multiboot:
 	dd FLAGS
 	dd CHECK
 
-section .bss
-align 16
 
 ; Initialize stack
-stack_bottom:
+section .bss
+align 16
+global __kernel_stack_top
+global __kernel_stack_bottom
+__kernel_stack_bottom:
 	resb 16384
-stack_top:
+__kernel_stack_top:
 
 ; Entry point
 section .text
 global _start
 extern kmain
 _start:
-	mov esp, stack_top	; Setup stack
+	mov esp, __kernel_stack_top
 	push eax
 	push ebx
 	call kmain		; Call kernel main

kernel/src/gdt.c

@@ -2,22 +2,9 @@
 #include <string.h>
 #include <gdt.h>
 
-static struct gdt_entries gdt;
+static struct gdt_entry gdt[GDT_ENTRIES];
 static struct gdt_pointer gdtp;
 static struct tss_pointer tss;
-struct tss_pointer* tssp = &tss;
-
-void gdt_loadTss(struct tss_pointer* ptr) {
-	size_t addr = (size_t)ptr;
-
-	gdt.tss.baseLow = (uint16_t)addr;
-	gdt.tss.baseMid = (uint8_t)(addr >> 16);
-	gdt.tss.flags1 = 0x89;
-	gdt.tss.flags2 = 0;
-	gdt.tss.baseHigh = (uint8_t)(addr >> 24);
-	
-	__asm__ volatile ("ltr %0" : : "rm"(SEGMENT_SEL(0, 0, 7)));
-}
 
 void gdt_reload(void) {
 	__asm__ volatile (
@@ -37,66 +24,41 @@ void gdt_reload(void) {
 	);
 }
 
+void tss_reload(void) {
+	__asm__ volatile ("ltr %0" : : "rm"(GDT_TSS));
+	gdt[5].access |= 0x02;
+}
+
 int gdt_init(void) {
 	// Null descriptor (0)
-	gdt.descriptors[0].limit = 0;
-	gdt.descriptors[0].baseLow = 0;
-	gdt.descriptors[0].baseMid = 0;
-	gdt.descriptors[0].access = 0;
-	gdt.descriptors[0].granulatiry = 0;
-	gdt.descriptors[0].baseHigh = 0;
+	gdt[0] = GDT_DESC(0, 0, 0, 0);
 
 	// Kernel code (8)
-	gdt.descriptors[1].limit = 0xffff;
-	gdt.descriptors[1].baseLow = 0;
-	gdt.descriptors[1].baseMid = 0;
-	gdt.descriptors[1].access = 0x9a;
-	gdt.descriptors[1].granulatiry = 0xcf;
-	gdt.descriptors[1].baseHigh = 0;
+	gdt[1] = GDT_DESC(0xfffff, 0, 0x9a, 0xc);
 
 	// Kernel data (16)
-	gdt.descriptors[2].limit = 0xffff;
-	gdt.descriptors[2].baseLow = 0;
-	gdt.descriptors[2].baseMid = 0;
-	gdt.descriptors[2].access = 0x90;
-	gdt.descriptors[2].granulatiry = 0xcf;
-	gdt.descriptors[2].baseHigh = 0;
+	gdt[2] = GDT_DESC(0xfffff, 0, 0x92, 0xc);
 
-	// SYSENTER/SYSEXIT
-	gdt.descriptors[3] = (struct gdt_entry){ 0 }; // (24)
-	gdt.descriptors[4] = (struct gdt_entry){ 0 }; // (32)
+	// User code (24)
+	gdt[3] = GDT_DESC(0xfffff, 0, 0xfa, 0xc);
 
-	// User code (40)
-	gdt.descriptors[5].limit = 0;
-	gdt.descriptors[5].baseLow = 0;
-	gdt.descriptors[5].baseMid = 0;
-	gdt.descriptors[5].access = 0xfa;
-	gdt.descriptors[5].granulatiry = 0x20;
-	gdt.descriptors[5].baseHigh = 0;
+	// User data (32)
+	gdt[4] = GDT_DESC(0xfffff, 0, 0xf2, 0xc);
 
-	// User data (48)
-	gdt.descriptors[6].limit = 0;
-	gdt.descriptors[6].baseLow = 0;
-	gdt.descriptors[6].baseMid = 0;
-	gdt.descriptors[6].access = 0xf2;
-	gdt.descriptors[6].granulatiry = 0;
-	gdt.descriptors[6].baseHigh = 0;
+	// TSS (40)
+	memset(&tss, 0, sizeof(tss));
+	gdt[5] = GDT_DESC(sizeof(tss) - 1, (uint32_t)&tss, 0x89, 0x00);
+	tss.iopb = sizeof(struct tss_pointer);
+	tss.esp0 = __kernel_stack_top;
+	tss.ss0 = GDT_KERNEL_DATA;
 
-	// TSS (56)
-	gdt.tss.length = 104;
-	gdt.tss.baseLow = 0;
-	gdt.tss.baseMid = 0;
-	gdt.tss.flags1 = 0x89;
-	gdt.tss.flags2 = 0;
-	gdt.tss.baseHigh = 0;
-
-	gdtp.limit = sizeof(struct gdt_entries) - 1;
+	// GDT Pointer
+	gdtp.limit = sizeof(gdt) - 1;
 	gdtp.base = (uint32_t)&gdt;
 
 	gdt_reload();
+	tss_reload();
 
-	memset(tssp, 0, sizeof(struct tss_pointer));
-	gdt_loadTss(tssp);
 	return 0;
 }
 

kernel/src/kernel.c

@@ -27,7 +27,6 @@ void kmain(void* ptr, uint32_t magic) {
 	gdt_init();
 	// isr_init();
 	// pag_init();
-	while (1);
 
 	debugf("Basic initialization complete!\n");