tree: https://git.kernel.org/pub/scm/linux/kernel/git/sashal/linux-stable.git v5.10-rc2-stable head: fff950790f1aeb42f8b38de431ac45069cf84a73 commit: 9b44c929d88ab86f807edb1c18f07d5e53e5baf2 [890/936] arm64: Rewrite Spectre-v2 mitigation code config: arm64-randconfig-r005-20201102 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project cc91554ebb66e8c9a4b8c67ca2f1343eaac10cf6) 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 # install arm64 cross compiling tool for clang build # apt-get install binutils-aarch64-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/sashal/linux-stable.git/c... git remote add sashal-linux-stable https://git.kernel.org/pub/scm/linux/kernel/git/sashal/linux-stable.git git fetch --no-tags sashal-linux-stable v5.10-rc2-stable git checkout 9b44c929d88ab86f807edb1c18f07d5e53e5baf2 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): install_bp_hardening_cb(cb); ^ arch/arm64/kernel/proton-pack.c:303:2: error: implicit declaration of function 'install_bp_hardening_cb' [-Werror,-Wimplicit-function-declaration] install_bp_hardening_cb(qcom_link_stack_sanitisation); ^ 2 errors generated. vim +/install_bp_hardening_cb +287 arch/arm64/kernel/proton-pack.c 261 262 static enum mitigation_state spectre_v2_enable_fw_mitigation(void) 263 { 264 bp_hardening_cb_t cb; 265 enum mitigation_state state; 266 267 state = spectre_v2_get_cpu_fw_mitigation_state(); 268 if (state != SPECTRE_MITIGATED) 269 return state; 270 271 if (spectre_v2_mitigations_off()) 272 return SPECTRE_VULNERABLE; 273 274 switch (arm_smccc_1_1_get_conduit()) { 275 case SMCCC_CONDUIT_HVC: 276 cb = call_hvc_arch_workaround_1; 277 break; 278 279 case SMCCC_CONDUIT_SMC: 280 cb = call_smc_arch_workaround_1; 281 break; 282 283 default: 284 return SPECTRE_VULNERABLE; 285 } 286 288 return SPECTRE_MITIGATED; 289 } 290 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org