x86: probe assembler capabilities via kconfig instead of makefile

Doing this probing inside of the Makefiles means we have a maze of
ifdefs inside the source code and child Makefiles that need to make
proper decisions on this too. Instead, we do it at Kconfig time, like
many other compiler and assembler options, which allows us to set up the
dependencies normally for full compilation units. In the process, the
ADX test changes to use %eax instead of %r10 so that it's valid in both
32-bit and 64-bit mode.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 8d078642b4bee9d639ec12547e6f08bacdd8ff96..70898a68fa1adab3205192530d6b1912ea29c862 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2931,3 +2931,5 @@ config HAVE_ATOMIC_IOMAP
 source "drivers/firmware/Kconfig"
 
 source "arch/x86/kvm/Kconfig"
+
+source "arch/x86/Kconfig.assembler"

diff --git a/arch/x86/Kconfig.assembler b/arch/x86/Kconfig.assembler
new file mode 100644 (file)
index 0000000..91230bf
--- /dev/null
+++ b/arch/x86/Kconfig.assembler
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2020 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+
+config AS_AVX2
+       def_bool $(as-instr,vpbroadcastb %xmm0$(comma)%ymm1)
+
+config AS_AVX512
+       def_bool $(as-instr,vpmovm2b %k1$(comma)%zmm5)
+
+config AS_SHA1_NI
+       def_bool $(as-instr,sha1msg1 %xmm0$(comma)%xmm1)
+
+config AS_SHA256_NI
+       def_bool $(as-instr,sha256msg1 %xmm0$(comma)%xmm1)
+
+config AS_ADX
+       def_bool $(as-instr,adox %eax$(comma)%eax)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index f32ef7b8d5cac47e15861145d297e6b9f9800088..b65ec63c7db7b2ec45e02bc32f08e037f55cc41f 100644 (file)
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -177,16 +177,6 @@ ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
        KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
 endif
 
-# does binutils support specific instructions?
-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)
-sha1_ni_instr :=$(call as-instr,sha1msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA1_NI=1)
-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 += $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
-KBUILD_CFLAGS += $(avx2_instr) $(avx512_instr) $(sha1_ni_instr) $(sha256_ni_instr) $(adx_instr)
-
 KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
 
 #

diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 292e71dc7ba4393aada6f1ce87b2e6791172b1d4..ed4e52270520313e58b4670c9dd9ed64aa562501 100644 (file)
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -83,7 +83,7 @@ nf_tables-objs := nf_tables_core.o nf_tables_api.o nft_chain_filter.o \
                  nft_set_pipapo.o
 
 ifdef CONFIG_X86_64
-ifneq (,$(findstring -DCONFIG_AS_AVX2=1,$(KBUILD_CFLAGS)))
+ifdef CONFIG_AS_AVX2
 nf_tables-objs += nft_set_pipapo_avx2.o
 endif
 endif