[PATCH 5.10 3/4] kbuild: check CONFIG_AS_IS_LLVM instead of LLVM_IAS

From: Nathan Chancellor <nathan@kernel.org>
To: gregkh@linuxfoundation.org, sashal@kernel.org
Cc: conor@kernel.org, stable@vger.kernel.org, llvm@lists.linux.dev,
	 Masahiro Yamada <masahiroy@kernel.org>,
	 Nick Desaulniers <ndesaulniers@google.com>,
	 Nathan Chancellor <nathan@kernel.org>
Subject: [PATCH 5.10 3/4] kbuild: check CONFIG_AS_IS_LLVM instead of LLVM_IAS
Date: Tue, 28 Mar 2023 17:08:31 -0700	[thread overview]
Message-ID: <20230328-riscv-zifencei-zicsr-5-10-v1-3-bccb3e16dc46@kernel.org> (raw)
In-Reply-To: <20230328-riscv-zifencei-zicsr-5-10-v1-0-bccb3e16dc46@kernel.org>

From: Masahiro Yamada <masahiroy@kernel.org>

commit 52cc02b910284d6bddba46cce402044ab775f314 upstream.

LLVM_IAS is the user interface to set the -(no-)integrated-as flag,
and it should be used only for that purpose.

LLVM_IAS is checked in some places to determine the assembler type,
but it is not precise.

For example,

 $ make CC=gcc LLVM_IAS=1

... will use the GNU assembler (i.e. binutils) since LLVM_IAS=1 is
effective only when $(CC) is clang.

Of course, 'CC=gcc LLVM_IAS=1' is an odd combination, but the build
system can be more robust against such insane input.

Commit ba64beb17493a ("kbuild: check the minimum assembler version in
Kconfig") introduced CONFIG_AS_IS_GNU/LLVM, which is more precise
because Kconfig checks the version string from the assembler in use.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
[nathan: Backport to 5.10]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 Makefile            | 2 +-
 arch/riscv/Makefile | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 1272e482abbe..3dfacb6fa973 100644
--- a/Makefile
+++ b/Makefile
@@ -851,7 +851,7 @@ else
 DEBUG_CFLAGS	+= -g
 endif
 
-ifeq ($(LLVM_IAS),1)
+ifdef CONFIG_AS_IS_LLVM
 KBUILD_AFLAGS	+= -g
 else
 KBUILD_AFLAGS	+= -Wa,-gdwarf-2
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 9446282b52ba..14cdeaa2bb32 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -40,7 +40,7 @@ ifeq ($(CONFIG_LD_IS_LLD),y)
 ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 150000; echo $$?),0)
 	KBUILD_CFLAGS += -mno-relax
 	KBUILD_AFLAGS += -mno-relax
-ifneq ($(LLVM_IAS),1)
+ifndef CONFIG_AS_IS_LLVM
 	KBUILD_CFLAGS += -Wa,-mno-relax
 	KBUILD_AFLAGS += -Wa,-mno-relax
 endif

-- 
2.40.0

