Return whether or not the given address corresponds to a syscall implementation.

def is_syscall_addr(self, addr):
        """
        Return whether or not the given address corresponds to a syscall implementation.
        """
        if self.kernel_base is None or addr < self.kernel_base:
            return False

        addr -= self.kernel_base

        if addr % self.syscall_addr_alignment != 0:
            return False

        addr //= self.syscall_addr_alignment
        return addr <= self.unknown_syscall_number