Re: [PATCH 06/16] x86: remove always-defined CONFIG_AS_SSSE3

[Nick Desaulniers]

On Tue, Mar 24, 2020 at 1:49 AM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
>
> CONFIG_AS_SSSE3 was introduced by commit 75aaf4c3e6a4 ("x86/raid6:
> correctly check for assembler capabilities").
>
> We raise the minimal supported binutils version from time to time.
> The last bump was commit 1fb12b35e5ff ("kbuild: Raise the minimum
> required binutils version to 2.21").

Looks like binutils gained SSE3 support in 2005; 2.21 was released in 2010.
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>

>
> I confirmed the code in $(call as-instr,...) can be assembled by the
> binutils 2.21 assembler and also by LLVM integrated assembler.
>
> Remove CONFIG_AS_SSSE3, which is always defined.
>
> I added ifdef CONFIG_X86 to lib/raid6/algos.c to avoid link errors
> on non-x86 architectures.
>
> lib/raid6/algos.c is built not only for the kernel but also for
> testing the library code from userspace. I added -DCONFIG_X86 to
> lib/raid6/test/Makefile to cator to this usecase.
>
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> Acked-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
> ---
>
>  arch/x86/Makefile              | 5 ++---
>  arch/x86/crypto/blake2s-core.S | 2 --
>  lib/raid6/algos.c              | 2 +-
>  lib/raid6/recov_ssse3.c        | 6 ------
>  lib/raid6/test/Makefile        | 4 +---
>  5 files changed, 4 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index e4a062313bb0..94f89612e024 100644
> --- a/arch/x86/Makefile
> +++ b/arch/x86/Makefile
> @@ -178,7 +178,6 @@ ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
>  endif
>
>  # does binutils support specific instructions?
> -asinstr += $(call as-instr,pshufb %xmm0$(comma)%xmm0,-DCONFIG_AS_SSSE3=1)
>  avx_instr := $(call as-instr,vxorps %ymm0$(comma)%ymm1$(comma)%ymm2,-DCONFIG_AS_AVX=1)
>  avx2_instr :=$(call as-instr,vpbroadcastb %xmm0$(comma)%ymm1,-DCONFIG_AS_AVX2=1)
>  avx512_instr :=$(call as-instr,vpmovm2b %k1$(comma)%zmm5,-DCONFIG_AS_AVX512=1)
> @@ -186,8 +185,8 @@ sha1_ni_instr :=$(call as-instr,sha1msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA1_NI=
>  sha256_ni_instr :=$(call as-instr,sha256msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA256_NI=1)
>  adx_instr := $(call as-instr,adox %r10$(comma)%r10,-DCONFIG_AS_ADX=1)
>
> -KBUILD_AFLAGS += $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
> -KBUILD_CFLAGS += $(asinstr) $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
> +KBUILD_AFLAGS += $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
> +KBUILD_CFLAGS += $(avx_instr) $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
>
>  KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
>
> diff --git a/arch/x86/crypto/blake2s-core.S b/arch/x86/crypto/blake2s-core.S
> index 24910b766bdd..2ca79974f819 100644
> --- a/arch/x86/crypto/blake2s-core.S
> +++ b/arch/x86/crypto/blake2s-core.S
> @@ -46,7 +46,6 @@ SIGMA2:
>  #endif /* CONFIG_AS_AVX512 */
>
>  .text
> -#ifdef CONFIG_AS_SSSE3
>  SYM_FUNC_START(blake2s_compress_ssse3)
>         testq           %rdx,%rdx
>         je              .Lendofloop
> @@ -174,7 +173,6 @@ SYM_FUNC_START(blake2s_compress_ssse3)
>  .Lendofloop:
>         ret
>  SYM_FUNC_END(blake2s_compress_ssse3)
> -#endif /* CONFIG_AS_SSSE3 */
>
>  #ifdef CONFIG_AS_AVX512
>  SYM_FUNC_START(blake2s_compress_avx512)
> diff --git a/lib/raid6/algos.c b/lib/raid6/algos.c
> index bf1b4765c8f6..df08664d3432 100644
> --- a/lib/raid6/algos.c
> +++ b/lib/raid6/algos.c
> @@ -97,13 +97,13 @@ void (*raid6_datap_recov)(int, size_t, int, void **);
>  EXPORT_SYMBOL_GPL(raid6_datap_recov);
>
>  const struct raid6_recov_calls *const raid6_recov_algos[] = {
> +#ifdef CONFIG_X86
>  #ifdef CONFIG_AS_AVX512
>         &raid6_recov_avx512,
>  #endif
>  #ifdef CONFIG_AS_AVX2
>         &raid6_recov_avx2,
>  #endif
> -#ifdef CONFIG_AS_SSSE3
>         &raid6_recov_ssse3,
>  #endif
>  #ifdef CONFIG_S390
> diff --git a/lib/raid6/recov_ssse3.c b/lib/raid6/recov_ssse3.c
> index 1de97d2405d0..4bfa3c6b60de 100644
> --- a/lib/raid6/recov_ssse3.c
> +++ b/lib/raid6/recov_ssse3.c
> @@ -3,8 +3,6 @@
>   * Copyright (C) 2012 Intel Corporation
>   */
>
> -#ifdef CONFIG_AS_SSSE3
> -
>  #include <linux/raid/pq.h>
>  #include "x86.h"
>
> @@ -328,7 +326,3 @@ const struct raid6_recov_calls raid6_recov_ssse3 = {
>  #endif
>         .priority = 1,
>  };
> -
> -#else
> -#warning "your version of binutils lacks SSSE3 support"
> -#endif
> diff --git a/lib/raid6/test/Makefile b/lib/raid6/test/Makefile
> index b9e6c3648be1..60021319ac78 100644
> --- a/lib/raid6/test/Makefile
> +++ b/lib/raid6/test/Makefile
> @@ -34,9 +34,7 @@ endif
>
>  ifeq ($(IS_X86),yes)
>          OBJS   += mmx.o sse1.o sse2.o avx2.o recov_ssse3.o recov_avx2.o avx512.o recov_avx512.o
> -        CFLAGS += $(shell echo "pshufb %xmm0, %xmm0" |         \
> -                    gcc -c -x assembler - >/dev/null 2>&1 &&   \
> -                    rm ./-.o && echo -DCONFIG_AS_SSSE3=1)
> +        CFLAGS += -DCONFIG_X86
>          CFLAGS += $(shell echo "vpbroadcastb %xmm0, %ymm1" |   \
>                      gcc -c -x assembler - >/dev/null 2>&1 &&   \
>                      rm ./-.o && echo -DCONFIG_AS_AVX2=1)
> --
> 2.17.1
>
> --

-- 
Thanks,
~Nick Desaulniers