tree:   https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git bpf/ftrace
head:   f6ca0faab8697bc6a3a6e4ffcb72b8a0a0a66558
commit: e201e5e6b442644c28e6c9a001ef2b7e4428aa51 [2/6] bpf: Add bpf ftrace link
config: arm-aspeed_g4_defconfig (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://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git/commit/?id=e201e5e6b442644c28e6c9a001ef2b7e4428aa51
        git remote add jolsa-perf https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
        git fetch --no-tags jolsa-perf bpf/ftrace
        git checkout e201e5e6b442644c28e6c9a001ef2b7e4428aa51
        # 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 >>):

   arm-linux-gnueabi-ld: kernel/bpf/syscall.o: in function `bpf_ftrace_function_call':
   syscall.c:(.text+0xbd8): undefined reference to `__bpf_prog_enter'
>> arm-linux-gnueabi-ld: syscall.c:(.text+0xbf8): undefined reference to `__bpf_prog_exit'

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