use ELF for kernel

2 files changed, 68 insertions, 6 deletions

diff --git a/stage2/main.asm b/stage2/main.asm
index 3cfb5d2..5027546 100644
--- a/stage2/main.asm
+++ b/stage2/main.asm
@@ -44,8 +44,69 @@ long_mode:
 	mov gs, ax
 	mov ss, ax
 
-	; align stack
-	and rsp, ~(0x0f)
-	sub rsp, 8
+	mov eax, [kernel_elf]
+	cmp eax, [.elf]
+	jne .fail
 
-	; kernel begins here
+	mov r8, [kernel_elf+32] ; program header pos
+	add r8, kernel_elf
+
+	movzx rbx, word[kernel_elf+54] ; program header size
+	movzx rdx, word[kernel_elf+56] ; num of program headers
+
+.header:
+	cmp rdx, 0
+	je .start
+
+	mov edi, [r8] ; type
+	cmp edi, 0
+	je .next
+
+	cmp edi, 1
+	je .load
+
+	cmp edi, 2
+	je .fail
+
+	cmp edi, 3
+	je .fail
+
+	jmp .next
+
+.load:
+	; zero out the segment
+	mov al, 0
+	mov rdi, [r8+16]
+	mov rcx, [r8+40]
+	rep stosb
+
+	; load from file
+	mov rdi, [r8+16]
+	mov rsi, [r8+8]
+	add rsi, kernel_elf
+	mov rcx, [r8+32]
+	rep movsb
+
+.next:
+
+	add r8, rbx
+	dec rdx
+	jmp .header
+
+.start:
+	; more stack space
+	mov rsp, 0x80000
+	xor rbp, rbp
+
+	; ELF entry point
+	mov rax, [kernel_elf+24]
+	call rax
+
+.fail:
+	cli
+	hlt
+	jmp $
+
+.elf: db 0x7f, "ELF"
+
+kernel_elf:
diff --git a/stage2/paging.asm b/stage2/paging.asm
index cedc1e9..cd6ea1c 100644
--- a/stage2/paging.asm
+++ b/stage2/paging.asm
@@ -8,13 +8,14 @@ paging:
 .clr_buf:
 	mov byte[di], 0
 	inc di
-	cmp di, PAGETABLE+0x4000
+	cmp di, PAGETABLE+0x5000
 	jne .clr_buf
 
 	; init 3 page map levels
 	mov dword[PAGETABLE+0x0000], PAGETABLE+0x1003
 	mov dword[PAGETABLE+0x1000], PAGETABLE+0x2003
 	mov dword[PAGETABLE+0x2000], PAGETABLE+0x3003
+	mov dword[PAGETABLE+0x2008], PAGETABLE+0x4003
 
 	; fill up level 4 page map
 	mov eax, 3
@@ -23,7 +24,7 @@ paging:
 	mov [di], eax
 	add di, 8
 	add eax, 0x1000
-	cmp eax, 0x100000
+	cmp eax, 0x200000
 	jb .build_pt
 
 	; enable paging and long mode