MSR and syscall changes

- Moved MSR code to separate files with an enum class
- Implemented syscall_enable in C++ using new MSR calls

src/kernel/syscall.s

@@ -1,35 +1,7 @@
 %include "push_all.inc"
 
-global syscall_enable
-syscall_enable:
-	; IA32_EFER - set bit 0, syscall enable
-	mov rcx, 0xc0000080
-	rdmsr
-	or rax, 0x1
-	wrmsr
-
-	; IA32_STAR - cs for syscall
-	mov rcx, 0xc0000081
-	mov rax, 0			; not used
-	mov rdx, 0x00180008	; GDT:3 (user code), GDT:1 (kernel code)
-	wrmsr
-
-	; IA32_LSTAR - RIP for syscall
-	mov rcx, 0xc0000082
-	lea rax, [rel syscall_handler_prelude]
-	mov rdx, rax
-	shr rdx, 32
-	wrmsr
-
-	; IA32_FMASK - FLAGS mask inside syscall
-	mov rcx, 0xc0000084
-	mov rax, 0x200
-	mov rdx, 0
-	wrmsr
-
-	ret
-
 extern syscall_handler
+global syscall_handler_prelude
 syscall_handler_prelude:
 	push 0		; ss, doesn't matter here
 	push rsp