| Message ID | 20210409221155.1113205-1-nathan@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | crypto: arm/curve25519 - Move '.fpu' after '.arch' | expand |
Seems reasonable to me.
Acked-by: Jason A. Donenfeld <Jason@zx2c4.com>
On Fri, Apr 9, 2021 at 3:12 PM Nathan Chancellor <nathan@kernel.org> 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 Another good link would be the one from Jessica describing more precisely what the ARM targets for Debian are: https://wiki.debian.org/ArchitectureSpecificsMemo#armel > > 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@vger.kernel.org > Fixes: d8f1308a025f ("crypto: arm/curve25519 - wire up NEON implementation") > Link: https://github.com/ClangBuiltLinux/continuous-integration2/issues/118 > Reported-by: Arnd Bergmann <arnd@arndb.de> > Suggested-by: Arnd Bergmann <arnd@arndb.de> > Suggested-by: Jessica Clarke <jrtc27@jrtc27.com> > Signed-off-by: Nathan Chancellor <nathan@kernel.org> Great work tracking down that Debian was carrying patches! Thank you! I've run this through the same 3 assemblers. Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> > --- > 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 >
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: stable@vger.kernel.org > Fixes: d8f1308a025f ("crypto: arm/curve25519 - wire up NEON implementation") > Link: https://github.com/ClangBuiltLinux/continuous-integration2/issues/118 > Reported-by: Arnd Bergmann <arnd@arndb.de> > Suggested-by: Arnd Bergmann <arnd@arndb.de> > Suggested-by: Jessica Clarke <jrtc27@jrtc27.com> > Signed-off-by: Nathan Chancellor <nathan@kernel.org> > --- > arch/arm/crypto/curve25519-core.S | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Patch applied. Thanks.
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)
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@vger.kernel.org Fixes: d8f1308a025f ("crypto: arm/curve25519 - wire up NEON implementation") Link: https://github.com/ClangBuiltLinux/continuous-integration2/issues/118 Reported-by: Arnd Bergmann <arnd@arndb.de> Suggested-by: Arnd Bergmann <arnd@arndb.de> Suggested-by: Jessica Clarke <jrtc27@jrtc27.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> --- arch/arm/crypto/curve25519-core.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) base-commit: e49d033bddf5b565044e2abe4241353959bc9120