PUSHFQ - x86-64 instruction reference

pushfqPush rflags 
Pushes the 64-bit rflags register onto the stack, lowering rsp by 8.
x86-64 and later
Intel's reference: PUSHF/PUSHFD/PUSHFQ 
CFPFAFZFSFDFOF –––––––
Changes no flag
Reads CF PF AF ZF SF TF IF DF OF
Forms  pushfq  
In 64-bit mode, pushf / pushfq subtract 8 from rsp and store a 64-bit image; pushfw subtracts 2 and stores the low 16 bits. pushfd is unavailable in this mode. The pushed 64-bit image has RF and VM cleared; it is not an exact copy of every bit of rflags.
 global _start

section .text
_start:
        mov rax, 12
        mov rbx, 5
        mov rcx, 3
        mov rsi, 9

        pushfq

        mov rax, 60         ; syscall 60: exit
        xor rdi, rdi
        syscall