tree:   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git objtool/core
head:   c59205d0022488e4625ffbcf7c87095dca05fa6d
commit: ad68a08875a6f809f833c958ff034df214973562 [30/39] x86/alternative: Implement .retpoline_sites support
config: um-x86_64_defconfig (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?id=ad68a08875a6f809f833c958ff034df214973562
        git remote add peterz-queue https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git
        git fetch --no-tags peterz-queue objtool/core
        git checkout ad68a08875a6f809f833c958ff034df214973562
        # save the attached .config to linux build tree
        mkdir build_dir
        make W=1 O=build_dir ARCH=um SUBARCH=x86_64 SHELL=/bin/bash

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 >>):

   /usr/bin/ld: arch/x86/um/../kernel/module.o: in function `module_finalize':
>> module.c:(.text+0x3b6): undefined reference to `apply_retpolines'
   collect2: error: ld returned 1 exit status

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