kbuild: allow to use GCC toolchain not in Clang search path

(commit ef8c4ed9db upstream)

When using a GCC cross toolchain which is not in a compiled in
Clang search path, Clang reverts to the system assembler and
linker. This leads to assembler or linker errors, depending on
which tool is first used for a given architecture.

It seems that Clang is not searching $PATH for a matching
assembler or linker.

Make sure that Clang picks up the correct assembler or linker by
passing the cross compilers bin directory as search path.

This allows to use Clang provided by distributions with GCC
toolchains not in /usr/bin.

Link: https://github.com/ClangBuiltLinux/linux/issues/78
Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-and-tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
[ND: adjusted to context, due to adjusting the context of my previous
backport of upstream's ae6b289a37]
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Stefan Agner 2018-12-05 16:45:26 -08:00 committed by Greg Kroah-Hartman
parent 51d137cab5
commit 4c219af48b

View file

@ -512,13 +512,15 @@ endif
ifeq ($(cc-name),clang)
ifneq ($(CROSS_COMPILE),)
CLANG_TARGET := -target $(notdir $(CROSS_COMPILE:%-=%))
GCC_TOOLCHAIN := $(realpath $(dir $(shell which $(LD)))/..)
GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD)))
CLANG_PREFIX := --prefix=$(GCC_TOOLCHAIN_DIR)
GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..)
endif
ifneq ($(GCC_TOOLCHAIN),)
CLANG_GCC_TC := -gcc-toolchain $(GCC_TOOLCHAIN)
endif
KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)
KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)
KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)
KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)
KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)