Hi Song,

I love your patch! Yet something to improve:

[auto build test ERROR on bpf-next/master]

url:    https://github.com/0day-ci/linux/commits/Song-Liu/introduce-BPF_PROG_TYPE_USER/20200801-165208
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: riscv-allyesconfig (attached as .config)
compiler: riscv64-linux-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
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=riscv 

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 >>):

   riscv64-linux-ld: kernel/bpf/syscall.o: in function `.LANCHOR1':
>> syscall.c:(.rodata+0xa50): undefined reference to `user_prog_ops'
   riscv64-linux-ld: kernel/bpf/verifier.o: in function `.LANCHOR1':
>> verifier.c:(.rodata+0x6b8): undefined reference to `user_verifier_ops'

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