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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Nathan Chancellor <natechancellor@gmail.com>,
        Will Deacon <will@kernel.org>
Subject: [PATCH 5.7 169/179] arm64: vdso32: Fix --prefix= value for newer versions of clang
Date:   Mon, 27 Jul 2020 16:05:44 +0200
Message-Id: <20200727134940.893164221@linuxfoundation.org>
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From: Nathan Chancellor <natechancellor@gmail.com>

commit 7b7891c7bdfd61fc9ed6747a0a05efe2394dddc6 upstream.

Newer versions of clang only look for $(COMPAT_GCC_TOOLCHAIN_DIR)as [1],
rather than $(COMPAT_GCC_TOOLCHAIN_DIR)$(CROSS_COMPILE_COMPAT)as,
resulting in the following build error:

$ make -skj"$(nproc)" ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- \
CROSS_COMPILE_COMPAT=arm-linux-gnueabi- LLVM=1 O=out/aarch64 distclean \
defconfig arch/arm64/kernel/vdso32/
...
/home/nathan/cbl/toolchains/llvm-binutils/bin/as: unrecognized option '-EL'
clang-12: error: assembler command failed with exit code 1 (use -v to see invocation)
make[3]: *** [arch/arm64/kernel/vdso32/Makefile:181: arch/arm64/kernel/vdso32/note.o] Error 1
...

Adding the value of CROSS_COMPILE_COMPAT (adding notdir to account for a
full path for CROSS_COMPILE_COMPAT) fixes this issue, which matches the
solution done for the main Makefile [2].

[1]: https://github.com/llvm/llvm-project/commit/3452a0d8c17f7166f479706b293caf6ac76ffd90
[2]: https://lore.kernel.org/lkml/20200721173125.1273884-1-maskray@google.com/

Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Cc: stable@vger.kernel.org
Link: https://github.com/ClangBuiltLinux/linux/issues/1099
Link: https://lore.kernel.org/r/20200723041509.400450-1-natechancellor@gmail.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/kernel/vdso32/Makefile |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm64/kernel/vdso32/Makefile
+++ b/arch/arm64/kernel/vdso32/Makefile
@@ -14,7 +14,7 @@ COMPAT_GCC_TOOLCHAIN_DIR := $(dir $(shel
 COMPAT_GCC_TOOLCHAIN := $(realpath $(COMPAT_GCC_TOOLCHAIN_DIR)/..)
 
 CC_COMPAT_CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE_COMPAT:%-=%))
-CC_COMPAT_CLANG_FLAGS += --prefix=$(COMPAT_GCC_TOOLCHAIN_DIR)
+CC_COMPAT_CLANG_FLAGS += --prefix=$(COMPAT_GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE_COMPAT))
 CC_COMPAT_CLANG_FLAGS += -no-integrated-as -Qunused-arguments
 ifneq ($(COMPAT_GCC_TOOLCHAIN),)
 CC_COMPAT_CLANG_FLAGS += --gcc-toolchain=$(COMPAT_GCC_TOOLCHAIN)