Broke it :)

kernel/include/gdt.h

@@ -110,6 +110,7 @@ struct tss_pointer {
 	uint32_t ssp;
 } __packed;
 
+void tss_esp0(uint32_t esp0);
 int gdt_init(void);
 
 #endif

kernel/linker.ld

@@ -2,47 +2,34 @@ OUTPUT_FORMAT("elf32-i386")
 OUTPUT_ARCH("i386");
 ENTRY(_start)
 
-/* Define correct program headers */
-PHDRS {
-	text	PT_LOAD		FLAGS((1 << 0) | (1 << 2));	/* Read, Execute */
-	rodata	PT_LOAD		FLAGS((1 << 0));		/* Read */
-	data	PT_LOAD		FLAGS((1 << 0) | (1 << 1));	/* Read, Write */
-}
-
 /* Define sections */
 SECTIONS {
-	/* 1MB is a conventional place for kernels */
+	. = 0x00100000;
-	. = 1M;
+	kernel_start = .;
 
-	__kernel_start = .;
+	.boot ALIGN(4K) : {
-	.text BLOCK(4K) : ALIGN(4K) {
 		*(.multiboot)
+		*(.boot)
+	}
+
+	. += 0xC0000000;
+
+	.text ALIGN(4K) : AT(ADDR(.text) - 0xC0000000) {
 		*(.text)
-	} : text
+	}
 
-	.rodata BLOCK(4K) : ALIGN(4K) {
+	.rodata ALIGN(4K) : AT(ADDR(.rodata) - 0xC0000000) {
 		*(.rodata)
-	} : rodata
+	}
 
-	.data BLOCK(4K) : ALIGN(4K) {
+	.data ALIGN(4K) : AT(ADDR(.data) - 0xC0000000) {
 		*(.data)
-	} : data
+	}
 
-	.bss BLOCK(4K) : ALIGN(4K) {
+	.bss ALIGN(4K) : AT(ADDR(.bss) - 0xC0000000) {
 		*(COMMON)
 		*(.bss)
-	} : data
-
-	/* Stack */
-	. = ALIGN(16);
-	__kernel_stack_bottom = .;
-	. += 16K;
-	__kernel_stack_top = .;
-
-	__kernel_end = .;
-
-	/DISCARD/ : {
-		*(.eh_frame)
-		*(.note*)
 	}
+
+	kernel_end = .;
 }

kernel/src/entry.s

@@ -28,13 +28,28 @@ __kernel_stack_bottom:
 __kernel_stack_top:
 
 ; Entry point
-section .text
+section .boot
 global _start
 extern kmain
 _start:	
+	; Temporary paging
+	mov edx, (init_pagedir - 0xC0000000)
+	mov cr3, edx
+
+	mov ecx, cr0
+	or ecx, 0x80000000
+	mov cr0, ecx
+
+	jmp $
+
+	jmp higher_half
+
+section .text
+higher_half:
 	mov esp, __kernel_stack_top
-	push eax
+	add ebx, 0xC0000000	; Make it a virtual address
-	push ebx
+	push eax 		; Magic
+	push ebx		; Multiboot info	
 	call kmain		; Call kernel main
 
 	; Hang if kernel returns
@@ -42,3 +57,19 @@ _start:
 .hlt:	hlt
 	jmp .hlt
 
+section .data
+align 4096
+global init_pagedir 
+init_pagedir:
+	dd 0b10000011 ; initial 4mb identity map, unmapped later
+	
+	times 768-1 dd 0 ; padding
+	
+	; hh kernel start, map 16 mb
+	dd (0 << 22) | 0b10000011 ; 0xC0000000
+	dd (1 << 22) | 0b10000011
+	dd (2 << 22) | 0b10000011
+	dd (3 << 22) | 0b10000011
+	times 256-4 dd 0 ; padding
+
+    ; dd initial_page_dir | 11b

kernel/src/gdt.c

@@ -29,6 +29,8 @@ void tss_reload(void) {
 	gdt[5].access |= 0x02;
 }
 
+void tss_esp0(uint32_t esp0) { tss.esp0 = esp0; }
+
 int gdt_init(void) {
 	// Null descriptor (0)
 	gdt[0] = GDT_DESC(0, 0, 0, 0);
@@ -47,7 +49,7 @@ int gdt_init(void) {
 
 	// TSS (40)
 	memset(&tss, 0, sizeof(tss));
-	gdt[5] = GDT_DESC(sizeof(tss) - 1, (uint32_t)&tss, 0x89, 0x00);
+	gdt[5] = GDT_DESC(sizeof(tss) - 1, (uint32_t)&tss, 0x89, 0x40);
 	tss.iopb = sizeof(struct tss_pointer);
 	tss.esp0 = __kernel_stack_top;
 	tss.ss0 = GDT_KERNEL_DATA;