On Thu, Jul 23, 2020 at 6:51 AM Nathan Chancellor natechancellor@gmail.com wrote:

On Thu, Jul 23, 2020 at 06:45:07AM +0200, Sedat Dilek wrote:

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On Thu, Jul 23, 2020 at 6:15 AM Nathan Chancellor natechancellor@gmail.com wrote:

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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].

[ CC Masahiro ]

Masahiro added a slightly adapted version of [2] in <kbuild.git#fixes>. Shall this go through kbuild subsystem or folded into [1]?

• Sedat -

[1] https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git/c...

Sorry, should have cc'd Masahiro, slipped my mind.

Note, I kept this separate as the patches have to go back different distances; only 5.7 has working clang support for vdso32, see commit a5d442f50a41 ("arm64: vdso32: Enable Clang Compilation") in Linus' tree, which appeared in 5.7-rc1 so this only needs to go into linux-5.7.y. The main patch needs to back all the way to 4.4 so we would need to drop this hunk when backporting, which would be annoying, as the main patch backports cleanly to 4.9.

Clarify your patch by adding...?

Cc: stable@vger.kernel.org # 5.7

It could be routed via the kbuild tree but the arm64 maintainers are pretty good at getting these fixes into the hands of Linus so I see no reason to go around them.

As you and arm64 maintainers prefer.

- Sedat -

Cheers, Nathan

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Cc: stable@vger.kernel.org Link: https://github.com/ClangBuiltLinux/linux/issues/1099 Signed-off-by: Nathan Chancellor natechancellor@gmail.com

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

diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile index d88148bef6b0..5139a5f19256 100644 --- a/arch/arm64/kernel/vdso32/Makefile +++ b/arch/arm64/kernel/vdso32/Makefile @@ -14,7 +14,7 @@ COMPAT_GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE_COMPAT)elfedit)) 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)

base-commit: d15be546031cf65a0fc34879beca02fd90fe7ac7

2.28.0.rc1

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