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commit1cf5f151d2upstream. -Wunaligned-access is a new warning in clang that is default enabled for arm and arm64 under certain circumstances within the clang frontend (see LLVM commit below). On v5.17-rc2, an ARCH=arm allmodconfig build shows 1284 total/70 unique instances of this warning (most of the instances are in header files), which is quite noisy. To keep a normal build green through CONFIG_WERROR, only show this warning with W=1, which will allow automated build systems to catch new instances of the warning so that the total number can be driven down to zero eventually since catching unaligned accesses at compile time would be generally useful. Cc: stable@vger.kernel.org Link:35737df4dcLink: https://github.com/ClangBuiltLinux/linux/issues/1569 Link: https://github.com/ClangBuiltLinux/linux/issues/1576 Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> [nathan: Fix conflict due to lack ofafe956c577] Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
79 lines
2.8 KiB
Makefile
79 lines
2.8 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# ==========================================================================
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#
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# make W=... settings
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#
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# W=1 - warnings that may be relevant and does not occur too often
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# W=2 - warnings that occur quite often but may still be relevant
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# W=3 - the more obscure warnings, can most likely be ignored
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#
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# $(call cc-option, -W...) handles gcc -W.. options which
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# are not supported by all versions of the compiler
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# ==========================================================================
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KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
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ifeq ("$(origin W)", "command line")
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export KBUILD_ENABLE_EXTRA_GCC_CHECKS := $(W)
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endif
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ifdef KBUILD_ENABLE_EXTRA_GCC_CHECKS
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warning- := $(empty)
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warning-1 := -Wextra -Wunused -Wno-unused-parameter
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warning-1 += -Wmissing-declarations
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warning-1 += -Wmissing-format-attribute
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warning-1 += $(call cc-option, -Wmissing-prototypes)
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warning-1 += -Wold-style-definition
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warning-1 += $(call cc-option, -Wmissing-include-dirs)
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warning-1 += $(call cc-option, -Wunused-but-set-variable)
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warning-1 += $(call cc-option, -Wunused-const-variable)
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warning-1 += $(call cc-option, -Wpacked-not-aligned)
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warning-1 += $(call cc-disable-warning, missing-field-initializers)
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warning-1 += $(call cc-disable-warning, sign-compare)
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warning-2 := -Waggregate-return
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warning-2 += -Wcast-align
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warning-2 += -Wdisabled-optimization
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warning-2 += -Wnested-externs
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warning-2 += -Wshadow
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warning-2 += $(call cc-option, -Wlogical-op)
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warning-2 += $(call cc-option, -Wmissing-field-initializers)
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warning-2 += $(call cc-option, -Wsign-compare)
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warning-2 += $(call cc-option, -Wmaybe-uninitialized)
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warning-2 += $(call cc-option, -Wunused-macros)
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warning-3 := -Wbad-function-cast
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warning-3 += -Wcast-qual
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warning-3 += -Wconversion
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warning-3 += -Wpacked
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warning-3 += -Wpadded
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warning-3 += -Wpointer-arith
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warning-3 += -Wredundant-decls
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warning-3 += -Wswitch-default
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warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
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warning-3 += $(call cc-option, -Wvla)
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warning := $(warning-$(findstring 1, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
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warning += $(warning-$(findstring 2, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
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warning += $(warning-$(findstring 3, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
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ifeq ("$(strip $(warning))","")
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$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
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endif
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KBUILD_CFLAGS += $(warning)
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else
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ifeq ($(cc-name),clang)
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KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
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KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
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KBUILD_CFLAGS += $(call cc-disable-warning, format)
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KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare)
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KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length)
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KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized)
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KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
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KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access)
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endif
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endif
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