mirror of
https://github.com/torvalds/linux.git
synced 2024-12-15 07:33:56 +00:00
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>
79 lines
2.8 KiB
Makefile
79 lines
2.8 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0-only
|
|
|
|
# cc-cross-prefix
|
|
# Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
|
|
# Return first <prefix> where a <prefix>gcc is found in PATH.
|
|
# If no gcc found in PATH with listed prefixes return nothing
|
|
#
|
|
# Note: '2>/dev/null' is here to force Make to invoke a shell. Otherwise, it
|
|
# would try to directly execute the shell builtin 'command'. This workaround
|
|
# should be kept for a long time since this issue was fixed only after the
|
|
# GNU Make 4.2.1 release.
|
|
cc-cross-prefix = $(firstword $(foreach c, $(1), \
|
|
$(if $(shell command -v -- $(c)gcc 2>/dev/null), $(c))))
|
|
|
|
# output directory for tests below
|
|
TMPOUT = $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_$$$$
|
|
|
|
# try-run
|
|
# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise)
|
|
# Exit code chooses option. "$$TMP" serves as a temporary file and is
|
|
# automatically cleaned up.
|
|
try-run = $(shell set -e; \
|
|
TMP=$(TMPOUT)/tmp; \
|
|
trap "rm -rf $(TMPOUT)" EXIT; \
|
|
mkdir -p $(TMPOUT); \
|
|
if ($(1)) >/dev/null 2>&1; \
|
|
then echo "$(2)"; \
|
|
else echo "$(3)"; \
|
|
fi)
|
|
|
|
# as-option
|
|
# Usage: aflags-y += $(call as-option,-Wa$(comma)-isa=foo,)
|
|
|
|
as-option = $(call try-run,\
|
|
$(CC) -Werror $(KBUILD_AFLAGS) $(1) -c -x assembler-with-cpp /dev/null -o "$$TMP",$(1),$(2))
|
|
|
|
# as-instr
|
|
# Usage: aflags-y += $(call as-instr,instr,option1,option2)
|
|
|
|
as-instr = $(call try-run,\
|
|
printf "%b\n" "$(1)" | $(CC) -Werror $(KBUILD_AFLAGS) -c -x assembler-with-cpp -o "$$TMP" -,$(2),$(3))
|
|
|
|
# __cc-option
|
|
# Usage: MY_CFLAGS += $(call __cc-option,$(CC),$(MY_CFLAGS),-march=winchip-c6,-march=i586)
|
|
__cc-option = $(call try-run,\
|
|
$(1) -Werror $(2) $(3) -c -x c /dev/null -o "$$TMP",$(3),$(4))
|
|
|
|
# cc-option
|
|
# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
|
|
|
|
cc-option = $(call __cc-option, $(CC),\
|
|
$(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS),$(1),$(2))
|
|
|
|
# cc-option-yn
|
|
# Usage: flag := $(call cc-option-yn,-march=winchip-c6)
|
|
cc-option-yn = $(call try-run,\
|
|
$(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
|
|
|
|
# cc-disable-warning
|
|
# Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
|
|
cc-disable-warning = $(call try-run,\
|
|
$(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
|
|
|
|
# gcc-min-version
|
|
# Usage: cflags-$(call gcc-min-version, 70100) += -foo
|
|
gcc-min-version = $(call test-ge, $(CONFIG_GCC_VERSION), $1)
|
|
|
|
# clang-min-version
|
|
# Usage: cflags-$(call clang-min-version, 110000) += -foo
|
|
clang-min-version = $(call test-ge, $(CONFIG_CLANG_VERSION), $1)
|
|
|
|
# ld-option
|
|
# Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y)
|
|
ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))
|
|
|
|
# ld-ifversion
|
|
# Usage: $(call ld-ifversion, -ge, 22252, y)
|
|
ld-ifversion = $(shell [ $(CONFIG_LD_VERSION)0 $(1) $(2)0 ] && echo $(3) || echo $(4))
|