From: Linus Walleij <linus.walleij@xxxxxxxxxx> [ Upstream commit 4aea16b7cfb76bd3361858ceee6893ef5c9b5570 ] When enabling expert mode CONFIG_EXPERT and using that power user mode to disable the branch prediction hardening !CONFIG_HARDEN_BRANCH_PREDICTOR, the assembly linker in CLANG notices that some assembly in proc-v7.S does not have corresponding C call sites, i.e. the prototypes in proc-v7-bugs.c are enclosed in ifdef CONFIG_HARDEN_BRANCH_PREDICTOR so this assembly: SYM_TYPED_FUNC_START(cpu_v7_smc_switch_mm) SYM_TYPED_FUNC_START(cpu_v7_hvc_switch_mm) Results in: ld.lld: error: undefined symbol: __kcfi_typeid_cpu_v7_smc_switch_mm >>> referenced by proc-v7.S:94 (.../arch/arm/mm/proc-v7.S:94) >>> arch/arm/mm/proc-v7.o:(.text+0x108) in archive vmlinux.a ld.lld: error: undefined symbol: __kcfi_typeid_cpu_v7_hvc_switch_mm >>> referenced by proc-v7.S:105 (.../arch/arm/mm/proc-v7.S:105) >>> arch/arm/mm/proc-v7.o:(.text+0x124) in archive vmlinux.a Fix this by adding an additional requirement that CONFIG_HARDEN_BRANCH_PREDICTOR has to be enabled to compile these assembly calls. Closes: https://lore.kernel.org/oe-kbuild-all/202411041456.ZsoEiD7T-lkp@xxxxxxxxx/ Reported-by: kernel test robot <lkp@xxxxxxxxx> Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> Signed-off-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/arm/mm/proc-v7.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index 5fb9a6aecb001..2cd9333426794 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -94,7 +94,7 @@ SYM_TYPED_FUNC_START(cpu_v7_dcache_clean_area) ret lr SYM_FUNC_END(cpu_v7_dcache_clean_area) -#ifdef CONFIG_ARM_PSCI +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR) .arch_extension sec SYM_TYPED_FUNC_START(cpu_v7_smc_switch_mm) stmfd sp!, {r0 - r3} -- 2.43.0
