Debian's clang carries a patch that makes the default FPU mode 'vfp3-d16' instead of 'neon' for 'armv7-a' to avoid generating NEON instructions on hardware that does not support them: https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/raw/5a61ca6f21b4ad8c6ac4970e5ea5a7b5b4486d22/debian/patches/clang-arm-default-vfp3-on-armv7a.patch https://bugs.debian.org/841474 https://bugs.debian.org/842142 https://bugs.debian.org/914268 This results in the following build error when clang's integrated assembler is used because the '.arch' directive overrides the '.fpu' directive: arch/arm/crypto/curve25519-core.S:25:2: error: instruction requires: NEON vmov.i32 q0, #1 ^ arch/arm/crypto/curve25519-core.S:26:2: error: instruction requires: NEON vshr.u64 q1, q0, #7 ^ arch/arm/crypto/curve25519-core.S:27:2: error: instruction requires: NEON vshr.u64 q0, q0, #8 ^ arch/arm/crypto/curve25519-core.S:28:2: error: instruction requires: NEON vmov.i32 d4, #19 ^ Shuffle the order of the '.arch' and '.fpu' directives so that the code builds regardless of the default FPU mode. This has been tested against both clang with and without Debian's patch and GCC. Cc: stable@xxxxxxxxxxxxxxx Fixes: d8f1308a025f ("crypto: arm/curve25519 - wire up NEON implementation") Link: https://github.com/ClangBuiltLinux/continuous-integration2/issues/118 Reported-by: Arnd Bergmann <arnd@xxxxxxxx> Suggested-by: Arnd Bergmann <arnd@xxxxxxxx> Suggested-by: Jessica Clarke <jrtc27@xxxxxxxxxx> Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx> --- arch/arm/crypto/curve25519-core.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/crypto/curve25519-core.S b/arch/arm/crypto/curve25519-core.S index be18af52e7dc..b697fa5d059a 100644 --- a/arch/arm/crypto/curve25519-core.S +++ b/arch/arm/crypto/curve25519-core.S @@ -10,8 +10,8 @@ #include <linux/linkage.h> .text -.fpu neon .arch armv7-a +.fpu neon .align 4 ENTRY(curve25519_neon) base-commit: e49d033bddf5b565044e2abe4241353959bc9120 -- 2.31.1.189.g2e36527f23
