[PATCH 08/16] x86: add comments about the binutils version to support code in as-instr

From: Masahiro Yamada <masahiroy@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: "David S . Miller" <davem@davemloft.net>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	clang-built-linux@googlegroups.com,
	Herbert Xu <herbert@gondor.apana.org.au>,
	linux-crypto@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	Peter Zijlstra <peterz@infradead.org>,
	"H . Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, linux-kbuild@vger.kernel.org,
	Masahiro Yamada <masahiroy@kernel.org>
Subject: [PATCH 08/16] x86: add comments about the binutils version to support code in as-instr
Date: Tue, 24 Mar 2020 17:48:13 +0900	[thread overview]
Message-ID: <20200324084821.29944-9-masahiroy@kernel.org> (raw)
In-Reply-To: <20200324084821.29944-1-masahiroy@kernel.org>

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").

We need to keep these as-instr checks because binutils 2.21 does not
support them.

I hope this will be a good hint which one can be dropped when we
bump the minimal binutils version next time.

As for the Clang/LLVM builds, we require very new LLVM version,
so the LLVM integrated assembler supports all of them.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Jason A. Donenfeld <Jason@zx2c4.com>
---

 arch/x86/Makefile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index f32ef7b8d5ca..4c57cb3018fb 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -178,10 +178,15 @@ ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
 endif
 
 # does binutils support specific instructions?
+# binutils >= 2.22
 avx2_instr :=$(call as-instr,vpbroadcastb %xmm0$(comma)%ymm1,-DCONFIG_AS_AVX2=1)
+# binutils >= 2.25
 avx512_instr :=$(call as-instr,vpmovm2b %k1$(comma)%zmm5,-DCONFIG_AS_AVX512=1)
+# binutils >= 2.24
 sha1_ni_instr :=$(call as-instr,sha1msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA1_NI=1)
+# binutils >= 2.24
 sha256_ni_instr :=$(call as-instr,sha256msg1 %xmm0$(comma)%xmm1,-DCONFIG_AS_SHA256_NI=1)
+# binutils >= 2.23
 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)
-- 
2.17.1

