From f784575fdbbee6e096866c0b506fd660dc5ffe1c Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Thu, 28 May 2020 19:40:44 +0200
Subject: Started higher-half kernel

---
 src/kernel/boot.asm  | 70 ++++++++++++++++++++++++++++++++++++++--------------
 src/kernel/linker.ld | 28 ++++++++++-----------
 2 files changed, 64 insertions(+), 34 deletions(-)

(limited to 'src')

diff --git a/src/kernel/boot.asm b/src/kernel/boot.asm
index 444b73a..6aa5c1a 100644
--- a/src/kernel/boot.asm
+++ b/src/kernel/boot.asm
@@ -1,4 +1,23 @@
-section .multiboot
+bits 32
+
+; Some variables
+kernel_virt_base equ 0xC0000000
+kernel_page_number equ (kernel_virt_base >> 22)
+kernel_stack equ 0x4000
+
+section .data
+	align 0x1000
+
+	boot_page_dir:
+		dd 0x00000083
+		times (kernel_page_number - 1) dd 0
+		dd 0x00000083
+		times (1024 - kernel_page_number - 1) dd 0
+
+section .text
+	align 4
+
+	multiboot:
 	header_start:
 		dd 0xe85250d6
 		dd 0
@@ -15,6 +34,12 @@ section .multiboot
 		dd 6 ; mmap
 		dd 13 ; smbios
 
+		; Page-align tag
+		align 8
+		dw 6
+		dw 0
+		dd 8
+
 		; Empty tag
 		align 8
 		dw 0
@@ -22,29 +47,36 @@ section .multiboot
 		dd 8
 	header_end:
 
-section .start_section
-	dd _start
+	global boot
+	extern kernel_main
+	boot:
+		mov ecx, (boot_page_dir - kernel_virt_base)
+		mov cr3, ecx
 
-; Initialize stack
-;section .bss
-;	align 16
-;
-;	STACK_BOTTOM:
-;		resb 0x4000
-;	STACK_TOP:
+		mov ecx, cr4
+		or ecx, 0x00000010
+		mov cr4, ecx
+		
+		mov ecx, cr0
+		or ecx, 0x80000000
+		mov cr0, ecx
 
-section .text
-	global _start
-	extern kernel_main
-	_start:
-		;mov esp, STACK_TOP
+		lea ecx, [higher_half]
+		jmp ecx
+
+	higher_half:
+		mov dword [boot_page_dir], 0
+		invlpg [0]
+		
+		mov esp, stack + kernel_stack
 		push esp
 		push ebx
 		push eax
 		cli
 		call kernel_main
-		jmp $
+		hlt
 
-section .end
-	global KERNEL_END
-	KERNEL_END:
\ No newline at end of file
+section .bss
+	align 32
+	stack:
+		resb kernel_stack
\ No newline at end of file
diff --git a/src/kernel/linker.ld b/src/kernel/linker.ld
index f134ccb..b7bde1d 100644
--- a/src/kernel/linker.ld
+++ b/src/kernel/linker.ld
@@ -1,34 +1,32 @@
-ENTRY(_start)
+ENTRY(boot)
+
+phys = 0x100000;
+offset = 0xC0000000;
+virt = offset + phys;
 
 SECTIONS
 {
-	. = 1M;
+	. = virt;
 
-	.text BLOCK(4K) : ALIGN(4K)
+	.text : AT (ADDR (.text) - offset)
 	{
-		*(.multiboot)
-		*(.start_section)
 		*(.text)
-	}
-
-	.rodata BLOCK(4K) : ALIGN(4K)
-	{
 		*(.rodata)
+		. = ALIGN(0x1000);
 	}
 
-	.data BLOCK(4K) : ALIGN(4K)
+	.data : AT (ADDR (.data) - offset)
 	{
 		*(.data)
+		. = ALIGN(0x1000);
 	}
 
-	.bss BLOCK(4K) : ALIGN(4K)
+	.bss : AT (ADDR (.bss) - offset)
 	{
 		*(.COMMON)
 		*(.bss)
+		. = ALIGN(0x1000);
 	}
 
-	.end BLOCK(4K) : ALIGN(4K)
-	{
-		*(.end)
-	}
+	KERNEL_END = .;
 }
\ No newline at end of file
-- 
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