| Message ID | 20220309191633.2307110-1-nathan@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | arm64: Do not include __READ_ONCE() block in assembly files | expand |
diff --git a/arch/arm64/include/asm/rwonce.h b/arch/arm64/include/asm/rwonce.h index 1bce62fa908a..56f7b1d4d54b 100644 --- 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>
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. Cc: stable@vger.kernel.org Fixes: e35123d83ee3 ("arm64: lto: Strengthen READ_ONCE() to acquire when CONFIG_LTO=y") Link: https://lore.kernel.org/r/20220309155716.3988480-1-maz@kernel.org/ Reported-by: Marc Zyngier <maz@kernel.org> Acked-by: James Morse <james.morse@arm.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> --- This is based on current mainline; if it should be based on a specific arm64 branch, please let me know. As 558c303c9734 is going to stable, I marked this for stable as well to avoid breaking Android. I used e35123d83ee3 for the fixes tag to make it clear to the stable team this should only go where that commit is present. If a different fixes tag should be used, please feel free to substitute. arch/arm64/include/asm/rwonce.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) base-commit: 330f4c53d3c2d8b11d86ec03a964b86dc81452f5