From: Nathan Chancellor <nathan@xxxxxxxxxx> commit 52c9f93a9c482251cb0d224faa602ba26d462be8 upstream. When building arm64 defconfig + CONFIG_LTO_CLANG_{FULL,THIN}=y after commit 558c303c9734 ("arm64: Mitigate spectre style branch history side channels"), the following error occurs: <instantiation>:4:2: error: invalid fixup for movz/movk instruction mov w0, #ARM_SMCCC_ARCH_WORKAROUND_3 ^ Marc figured out that moving "#include <linux/init.h>" in include/linux/arm-smccc.h into a !__ASSEMBLY__ block resolves it. The full include chain with CONFIG_LTO=y from include/linux/arm-smccc.h: include/linux/init.h include/linux/compiler.h arch/arm64/include/asm/rwonce.h arch/arm64/include/asm/alternative-macros.h arch/arm64/include/asm/assembler.h The asm/alternative-macros.h include in asm/rwonce.h only happens when CONFIG_LTO is set, which ultimately casues asm/assembler.h to be included before the definition of ARM_SMCCC_ARCH_WORKAROUND_3. As a result, the preprocessor does not expand ARM_SMCCC_ARCH_WORKAROUND_3 in __mitigate_spectre_bhb_fw, which results in the error above. Avoid this problem by just avoiding the CONFIG_LTO=y __READ_ONCE() block in asm/rwonce.h with assembly files, as nothing in that block is useful to assembly files, which allows ARM_SMCCC_ARCH_WORKAROUND_3 to be properly expanded with CONFIG_LTO=y builds. Fixes: e35123d83ee3 ("arm64: lto: Strengthen READ_ONCE() to acquire when CONFIG_LTO=y") Cc: <stable@xxxxxxxxxxxxxxx> # 5.11.x Link: https://lore.kernel.org/r/20220309155716.3988480-1-maz@xxxxxxxxxx/ Reported-by: Marc Zyngier <maz@xxxxxxxxxx> Acked-by: James Morse <james.morse@xxxxxxx> Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220309191633.2307110-1-nathan@xxxxxxxxxx Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm64/include/asm/rwonce.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/arch/arm64/include/asm/rwonce.h +++ b/arch/arm64/include/asm/rwonce.h @@ -5,7 +5,7 @@ #ifndef __ASM_RWONCE_H #define __ASM_RWONCE_H -#ifdef CONFIG_LTO +#if defined(CONFIG_LTO) && !defined(__ASSEMBLY__) #include <linux/compiler_types.h> #include <asm/alternative-macros.h> @@ -66,7 +66,7 @@ }) #endif /* !BUILD_VDSO */ -#endif /* CONFIG_LTO */ +#endif /* CONFIG_LTO && !__ASSEMBLY__ */ #include <asm-generic/rwonce.h> Patches currently in stable-queue which might be from nathan@xxxxxxxxxx are queue-5.15/arm-fix-build-error-when-bpf_syscall-is-disabled.patch queue-5.15/arm-do-not-use-nocrossrefs-directive-with-ld.lld.patch queue-5.15/arm64-do-not-include-__read_once-block-in-assembly-files.patch