; priv_64.asm   for testing that average user
;               can not execute privileged instructions 
; Assemble:	nasm -f elf64 priv_64.asm
; Link:		gcc -o priv_64  priv_64.o
; Run:		./priv_64
; Output:
; it should stop with a system caught error

        global main		; the standard gcc entry point
        extern	printf		; the C function, to be called
fmt:    db "bad! Still running",10,0	; The printf format, "\n",'0'


        section .text           ; try to halt the computer
main:				; the program label for the entry point
        push    rbp		; set up stack frame

	hlt			; should be error, only allowed in CPL=0

        mov	rdi,fmt		; address of format string
	mov	rax,0
	call	printf

        pop     rbp
	mov	rax,0		; normal, no error, return value
	ret			; return