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: [email protected]
Fixes: d8f1308a025f ("crypto: arm/curve25519 - wire up NEON implementation")
Link: https://github.com/ClangBuiltLinux/continuous-integration2/issues/118
Reported-by: Arnd Bergmann <[email protected]>
Suggested-by: Arnd Bergmann <[email protected]>
Suggested-by: Jessica Clarke <[email protected]>
Signed-off-by: Nathan Chancellor <[email protected]>
---
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
Seems reasonable to me.
Acked-by: Jason A. Donenfeld <[email protected]>
On Fri, Apr 09, 2021 at 03:11:55PM -0700, Nathan Chancellor wrote:
> 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: [email protected]
> Fixes: d8f1308a025f ("crypto: arm/curve25519 - wire up NEON implementation")
> Link: https://github.com/ClangBuiltLinux/continuous-integration2/issues/118
> Reported-by: Arnd Bergmann <[email protected]>
> Suggested-by: Arnd Bergmann <[email protected]>
> Suggested-by: Jessica Clarke <[email protected]>
> Signed-off-by: Nathan Chancellor <[email protected]>
> ---
> arch/arm/crypto/curve25519-core.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
Patch applied. Thanks.
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt