1.global vfork
 2.type vfork,@function
 3vfork:
 4	pop %rdx
 5	mov $0x4000003a,%eax /* SYS_vfork */
 6	syscall
 7	push %rdx
 8	mov %rax,%rdi
 9	.hidden __syscall_ret
10	jmp __syscall_ret