reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # https://github.com/xinli-intel/linux-fred-public/commit/b25e2be0204d8e7095a997b52afad35a7beb057a
        git remote add xinli-intel-fred-public https://github.com/xinli-intel/linux-fred-public.git
        git fetch --no-tags xinli-intel-fred-public fix_sp_calculation
        git checkout b25e2be0204d8e7095a997b52afad35a7beb057a
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=x86_64 olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=x86_64 SHELL=/bin/bash arch/x86/events/intel/