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d5c8d6e0fa
as-instr uses KBUILD_AFLAGS, but as-option uses KBUILD_CFLAGS. This can
cause as-option to fail unexpectedly when CONFIG_WERROR is set, because
clang will emit -Werror,-Wunused-command-line-argument for various -m
and -f flags in KBUILD_CFLAGS for assembler sources.
Callers of as-option and as-instr should be adding flags to
KBUILD_AFLAGS / aflags-y, not KBUILD_CFLAGS / cflags-y. Use
KBUILD_AFLAGS in all macros to clear up the initial problem.
Unfortunately, -Wunused-command-line-argument can still be triggered
with clang by the presence of warning flags or macro definitions because
'-x assembler' is used, instead of '-x assembler-with-cpp', which will
consume these flags. Switch to '-x assembler-with-cpp' in places where
'-x assembler' is used, as the compiler is always used as the driver for
out of line assembler sources in the kernel.
Finally, add -Werror to these macros so that they behave consistently
whether or not CONFIG_WERROR is set.
[nathan: Reworded and expanded on problems in commit message
Use '-x assembler-with-cpp' in a couple more places]
Link: https://github.com/ClangBuiltLinux/linux/issues/1699
Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
66 lines
2.6 KiB
Plaintext
66 lines
2.6 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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# Kconfig helper macros
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# Convenient variables
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comma := ,
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quote := "
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squote := '
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empty :=
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space := $(empty) $(empty)
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dollar := $
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right_paren := )
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left_paren := (
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# $(if-success,<command>,<then>,<else>)
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# Return <then> if <command> exits with 0, <else> otherwise.
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if-success = $(shell,{ $(1); } >/dev/null 2>&1 && echo "$(2)" || echo "$(3)")
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# $(success,<command>)
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# Return y if <command> exits with 0, n otherwise
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success = $(if-success,$(1),y,n)
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# $(failure,<command>)
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# Return n if <command> exits with 0, y otherwise
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failure = $(if-success,$(1),n,y)
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# $(cc-option,<flag>)
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# Return y if the compiler supports <flag>, n otherwise
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cc-option = $(success,trap "rm -rf .tmp_$$" EXIT; mkdir .tmp_$$; $(CC) -Werror $(CLANG_FLAGS) $(1) -c -x c /dev/null -o .tmp_$$/tmp.o)
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# $(ld-option,<flag>)
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# Return y if the linker supports <flag>, n otherwise
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ld-option = $(success,$(LD) -v $(1))
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# $(as-instr,<instr>)
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# Return y if the assembler supports <instr>, n otherwise
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as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) -c -x assembler-with-cpp -o /dev/null -)
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# check if $(CC) and $(LD) exist
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$(error-if,$(failure,command -v $(CC)),C compiler '$(CC)' not found)
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$(error-if,$(failure,command -v $(LD)),linker '$(LD)' not found)
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# Get the C compiler name, version, and error out if it is not supported.
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cc-info := $(shell,$(srctree)/scripts/cc-version.sh $(CC))
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$(error-if,$(success,test -z "$(cc-info)"),Sorry$(comma) this C compiler is not supported.)
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cc-name := $(shell,set -- $(cc-info) && echo $1)
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cc-version := $(shell,set -- $(cc-info) && echo $2)
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# Get the assembler name, version, and error out if it is not supported.
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as-info := $(shell,$(srctree)/scripts/as-version.sh $(CC) $(CLANG_FLAGS))
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$(error-if,$(success,test -z "$(as-info)"),Sorry$(comma) this assembler is not supported.)
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as-name := $(shell,set -- $(as-info) && echo $1)
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as-version := $(shell,set -- $(as-info) && echo $2)
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# Get the linker name, version, and error out if it is not supported.
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ld-info := $(shell,$(srctree)/scripts/ld-version.sh $(LD))
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$(error-if,$(success,test -z "$(ld-info)"),Sorry$(comma) this linker is not supported.)
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ld-name := $(shell,set -- $(ld-info) && echo $1)
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ld-version := $(shell,set -- $(ld-info) && echo $2)
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# machine bit flags
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# $(m32-flag): -m32 if the compiler supports it, or an empty string otherwise.
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# $(m64-flag): -m64 if the compiler supports it, or an empty string otherwise.
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cc-option-bit = $(if-success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null,$(1))
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m32-flag := $(cc-option-bit,-m32)
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m64-flag := $(cc-option-bit,-m64)
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