Hi Leo,

I love your patch! Yet something to improve:

[auto build test ERROR on tip/perf/core]
[also build test ERROR on soc/for-next linus/master v5.11-rc2 next-20210108]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Leo-Yan/coresight-etm-perf-Fix-pid-tracing-with-VHE/20210109-155234
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git c2208046bba6842dc232a600dc5cafc2fca41078
config: arm-randconfig-r015-20210108 (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/c4fd6815f979493a552f74d7524f59620df9893c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Leo-Yan/coresight-etm-perf-Fix-pid-tracing-with-VHE/20210109-155234
        git checkout c4fd6815f979493a552f74d7524f59620df9893c
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm 

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

All errors (new ones prefixed by >>):

   drivers/hwtracing/coresight/coresight-etm-perf.c: In function 'format_attr_pid_show':
>> drivers/hwtracing/coresight/coresight-etm-perf.c:43:16: error: implicit declaration of function 'is_kernel_in_hyp_mode' [-Werror=implicit-function-declaration]
      43 |  int pid_fmt = is_kernel_in_hyp_mode() ? ETM_OPT_CTXTID_IN_VMID : ETM_OPT_CTXTID;
         |                ^~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/is_kernel_in_hyp_mode +43 drivers/hwtracing/coresight/coresight-etm-perf.c

    38	
    39	static ssize_t format_attr_pid_show(struct device *dev,
    40					    struct device_attribute *attr,
    41					    char *page)
    42	{
  > 43		int pid_fmt = is_kernel_in_hyp_mode() ? ETM_OPT_CTXTID_IN_VMID : ETM_OPT_CTXTID;
    44	
    45		return sprintf(page, "config:%d\n", pid_fmt);
    46	}
    47	

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