tree: https://git.kernel.org/pub/scm/linux/kernel/git/broonie/misc.git arm64-bti head: 96593076d429c01908148240e3931161cea2541e commit: cae9a66b3abe820eae568b60288268311fcaf47f [8/13] arm64: traps: Shuffle code to eliminate forward declarations config: arm64-alldefconfig (attached as .config) compiler: aarch64-linux-gcc (GCC) 9.2.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout cae9a66b3abe820eae568b60288268311fcaf47f # save the attached .config to linux build tree GCC_VERSION=9.2.0 make.cross ARCH=arm64 If you fix the issue, kindly add following tag Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): arch/arm64/kernel/traps.c: In function 'do_sysinstr': 731 | for (hook = sys64_hooks; hook->handler; hook++) | ^~~~~~~~~~~ | sys64_hook arch/arm64/kernel/traps.c:731:14: note: each undeclared identifier is reported only once for each function it appears in 731 | for (hook = sys64_hooks; hook->handler; hook++) | ^~ 731 | for (hook = sys64_hooks; hook->handler; hook++) | ^~ vim +731 arch/arm64/kernel/traps.c 70c63cdfd6ee615 Marc Zyngier 2018-09-27 726 afa7c0e5b965cdb James Morse 2019-10-25 727 void do_sysinstr(unsigned int esr, struct pt_regs *regs) 9dbd5bb25c56e35 Suzuki K Poulose 2016-09-09 728 { 37143dcc44f8f33 Mark Rutland 2019-08-13 729 const struct sys64_hook *hook; 9dbd5bb25c56e35 Suzuki K Poulose 2016-09-09 730 9dbd5bb25c56e35 Suzuki K Poulose 2016-09-09 @731 for (hook = sys64_hooks; hook->handler; hook++) 9dbd5bb25c56e35 Suzuki K Poulose 2016-09-09 732 if ((hook->esr_mask & esr) == hook->esr_val) { 9dbd5bb25c56e35 Suzuki K Poulose 2016-09-09 733 hook->handler(esr, regs); 9dbd5bb25c56e35 Suzuki K Poulose 2016-09-09 734 return; 9dbd5bb25c56e35 Suzuki K Poulose 2016-09-09 735 } 9dbd5bb25c56e35 Suzuki K Poulose 2016-09-09 736 49f6cba617fef4b Mark Rutland 2017-01-27 737 /* 49f6cba617fef4b Mark Rutland 2017-01-27 738 * New SYS instructions may previously have been undefined at EL0. Fall 49f6cba617fef4b Mark Rutland 2017-01-27 739 * back to our usual undefined instruction handler so that we handle 49f6cba617fef4b Mark Rutland 2017-01-27 740 * these consistently. 49f6cba617fef4b Mark Rutland 2017-01-27 741 */ 49f6cba617fef4b Mark Rutland 2017-01-27 742 do_undefinstr(regs); 9dbd5bb25c56e35 Suzuki K Poulose 2016-09-09 743 } b6e43c0e3129ffe James Morse 2019-10-25 744 NOKPROBE_SYMBOL(do_sysinstr); 9dbd5bb25c56e35 Suzuki K Poulose 2016-09-09 745 :::::: The code at line 731 was first introduced by commit :::::: 9dbd5bb25c56e35e6b4c34d968689a1ded850924 arm64: Refactor sysinstr exception handling :::::: TO: Suzuki K Poulose <suzuki.poulose(a)arm.com&gt; :::::: CC: Will Deacon <will.deacon(a)arm.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org