From: Linus Walleij linus.walleij@linaro.org

[ 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@intel.com/

Reported-by: kernel test robot lkp@intel.com Reviewed-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: Russell King (Oracle) rmk+kernel@armlinux.org.uk Signed-off-by: Sasha Levin sashal@kernel.org --- 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 e351d682c2e36..8bde80b31a861 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -94,7 +94,7 @@ ENTRY(cpu_v7_dcache_clean_area) ret lr ENDPROC(cpu_v7_dcache_clean_area)

-#ifdef CONFIG_ARM_PSCI +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR) .arch_extension sec ENTRY(cpu_v7_smc_switch_mm) stmfd sp!, {r0 - r3}