tree:   https://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-misc.git lto-5.13-1-wip
head:   45fc24254df69291f9ebd597bc747df2eb61ee3a
commit: 45fc24254df69291f9ebd597bc747df2eb61ee3a [36/36] x86/paravirt/lto: Export native_steal_clock
config: x86_64-randconfig-s022-20210426 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-341-g8af24329-dirty
        # https://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-misc.git/commit/?id=45fc24254df69291f9ebd597bc747df2eb61ee3a
        git remote add ak https://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-misc.git
        git fetch --no-tags ak lto-5.13-1-wip
        git checkout 45fc24254df69291f9ebd597bc747df2eb61ee3a
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> arch/x86/kernel/paravirt.c:127:15: warning: no previous prototype for 'native_steal_clock' [-Wmissing-prototypes]
     127 | __visible u64 native_steal_clock(int cpu)
         |               ^~~~~~~~~~~~~~~~~~


vim +/native_steal_clock +127 arch/x86/kernel/paravirt.c

   126	
 > 127	__visible u64 native_steal_clock(int cpu)
   128	{
   129		return 0;
   130	}
   131	

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0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org