| # SPDX-License-Identifier: GPL-2.0 |
| # ========================================================================== |
| # make W=... settings |
| # |
| # There are four warning groups enabled by W=1, W=2, W=3, and W=e |
| # They are independent, and can be combined like W=12 or W=123e. |
| # ========================================================================== |
| |
| # Default set of warnings, always enabled |
| KBUILD_CFLAGS += -Wall |
| KBUILD_CFLAGS += -Wextra |
| KBUILD_CFLAGS += -Wundef |
| KBUILD_CFLAGS += -Werror=implicit-function-declaration |
| KBUILD_CFLAGS += -Werror=implicit-int |
| KBUILD_CFLAGS += -Werror=return-type |
| KBUILD_CFLAGS += -Werror=strict-prototypes |
| KBUILD_CFLAGS += -Wno-format-security |
| KBUILD_CFLAGS += -Wno-trigraphs |
| KBUILD_CFLAGS += $(call cc-option, -Wno-frame-address) |
| KBUILD_CFLAGS += $(call cc-option, -Wno-address-of-packed-member) |
| KBUILD_CFLAGS += -Wmissing-declarations |
| KBUILD_CFLAGS += -Wmissing-prototypes |
| |
| ifneq ($(CONFIG_FRAME_WARN),0) |
| KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN) |
| endif |
| |
| KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds |
| |
| ifdef CONFIG_CC_IS_CLANG |
| # The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable. |
| KBUILD_CFLAGS += -Wno-gnu |
| |
| # Clang checks for overflow/truncation with '%p', while GCC does not: |
| # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111219 |
| KBUILD_CFLAGS += $(call cc-option, -Wno-format-overflow-non-kprintf) |
| KBUILD_CFLAGS += $(call cc-option, -Wno-format-truncation-non-kprintf) |
| |
| # Clang may emit a warning when a const variable, such as the dummy variables |
| # in typecheck(), or const member of an aggregate type are not initialized, |
| # which can result in unexpected behavior. However, in many audited cases of |
| # the "field" variant of the warning, this is intentional because the field is |
| # never used within a particular call path, the field is within a union with |
| # other non-const members, or the containing object is not const so the field |
| # can be modified via memcpy() / memset(). While the variable warning also gets |
| # disabled with this same switch, there should not be too much coverage lost |
| # because -Wuninitialized will still flag when an uninitialized const variable |
| # is used. |
| KBUILD_CFLAGS += $(call cc-option, -Wno-default-const-init-unsafe) |
| else |
| |
| # gcc inanely warns about local variables called 'main' |
| KBUILD_CFLAGS += -Wno-main |
| endif |
| |
| # These result in bogus false positives |
| KBUILD_CFLAGS += $(call cc-option, -Wno-dangling-pointer) |
| |
| # Stack Variable Length Arrays (VLAs) must not be used in the kernel. |
| # Function array parameters should, however, be usable, but -Wvla will |
| # warn for those. Clang has no way yet to distinguish between the VLA |
| # types, so depend on GCC for now to keep stack VLAs out of the tree. |
| # https://github.com/llvm/llvm-project/issues/57098 |
| # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98217 |
| KBUILD_CFLAGS += $(call cc-option,-Wvla-larger-than=1) |
| |
| # disable pointer signed / unsigned warnings in gcc 4.0 |
| KBUILD_CFLAGS += -Wno-pointer-sign |
| |
| # In order to make sure new function cast mismatches are not introduced |
| # in the kernel (to avoid tripping CFI checking), the kernel should be |
| # globally built with -Wcast-function-type. |
| KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type) |
| |
| # Currently, disable -Wstringop-overflow for GCC 11, globally. |
| KBUILD_CFLAGS-$(CONFIG_CC_NO_STRINGOP_OVERFLOW) += $(call cc-option, -Wno-stringop-overflow) |
| KBUILD_CFLAGS-$(CONFIG_CC_STRINGOP_OVERFLOW) += $(call cc-option, -Wstringop-overflow) |
| |
| # Currently, disable -Wunterminated-string-initialization as broken |
| KBUILD_CFLAGS += $(call cc-option, -Wno-unterminated-string-initialization) |
| |
| # The allocators already balk at large sizes, so silence the compiler |
| # warnings for bounds checks involving those possible values. While |
| # -Wno-alloc-size-larger-than would normally be used here, earlier versions |
| # of gcc (<9.1) weirdly don't handle the option correctly when _other_ |
| # warnings are produced (?!). Using -Walloc-size-larger-than=SIZE_MAX |
| # doesn't work (as it is documented to), silently resolving to "0" prior to |
| # version 9.1 (and producing an error more recently). Numeric values larger |
| # than PTRDIFF_MAX also don't work prior to version 9.1, which are silently |
| # ignored, continuing to default to PTRDIFF_MAX. So, left with no other |
| # choice, we must perform a versioned check to disable this warning. |
| # https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au |
| KBUILD_CFLAGS-$(call gcc-min-version, 90100) += -Wno-alloc-size-larger-than |
| KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH) |
| |
| # Prohibit date/time macros, which would make the build non-deterministic |
| KBUILD_CFLAGS += -Werror=date-time |
| |
| # enforce correct pointer usage |
| KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types) |
| |
| # Require designated initializers for all marked structures |
| KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init) |
| |
| # Warn if there is an enum types mismatch |
| KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion) |
| |
| KBUILD_CFLAGS += -Wunused |
| |
| # |
| # W=1 - warnings which may be relevant and do not occur too often |
| # |
| ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),) |
| |
| KBUILD_CFLAGS += -Wmissing-format-attribute |
| KBUILD_CFLAGS += -Wmissing-include-dirs |
| KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable) |
| |
| KBUILD_CPPFLAGS += -Wundef |
| KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1 |
| |
| else |
| |
| # Some diagnostics enabled by default are noisy. |
| # Suppress them by using -Wno... except for W=1. |
| KBUILD_CFLAGS += $(call cc-option, -Wno-unused-but-set-variable) |
| KBUILD_CFLAGS += $(call cc-option, -Wno-unused-const-variable) |
| KBUILD_CFLAGS += $(call cc-option, -Wno-packed-not-aligned) |
| KBUILD_CFLAGS += $(call cc-option, -Wno-format-overflow) |
| ifdef CONFIG_CC_IS_GCC |
| KBUILD_CFLAGS += $(call cc-option, -Wno-format-truncation) |
| endif |
| KBUILD_CFLAGS += $(call cc-option, -Wno-stringop-truncation) |
| |
| KBUILD_CFLAGS += -Wno-override-init # alias for -Wno-initializer-overrides in clang |
| |
| ifdef CONFIG_CC_IS_CLANG |
| # Clang before clang-16 would warn on default argument promotions. |
| ifneq ($(call clang-min-version, 160000),y) |
| # Disable -Wformat |
| KBUILD_CFLAGS += -Wno-format |
| # Then re-enable flags that were part of the -Wformat group that aren't |
| # problematic. |
| KBUILD_CFLAGS += -Wformat-extra-args -Wformat-invalid-specifier |
| KBUILD_CFLAGS += -Wformat-zero-length -Wnonnull |
| # Requires clang-12+. |
| ifeq ($(call clang-min-version, 120000),y) |
| KBUILD_CFLAGS += -Wformat-insufficient-args |
| endif |
| endif |
| KBUILD_CFLAGS += $(call cc-option, -Wno-pointer-to-enum-cast) |
| KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare |
| KBUILD_CFLAGS += $(call cc-option, -Wno-unaligned-access) |
| KBUILD_CFLAGS += -Wno-enum-compare-conditional |
| endif |
| |
| endif |
| |
| # |
| # W=2 - warnings which occur quite often but may still be relevant |
| # |
| ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),) |
| |
| KBUILD_CFLAGS += -Wdisabled-optimization |
| KBUILD_CFLAGS += -Wshadow |
| KBUILD_CFLAGS += $(call cc-option, -Wlogical-op) |
| KBUILD_CFLAGS += $(call cc-option, -Wunused-macros) |
| |
| KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2 |
| |
| else |
| |
| # The following turn off the warnings enabled by -Wextra |
| KBUILD_CFLAGS += -Wno-missing-field-initializers |
| KBUILD_CFLAGS += -Wno-type-limits |
| KBUILD_CFLAGS += -Wno-shift-negative-value |
| |
| ifdef CONFIG_CC_IS_CLANG |
| KBUILD_CFLAGS += -Wno-enum-enum-conversion |
| endif |
| |
| ifdef CONFIG_CC_IS_GCC |
| KBUILD_CFLAGS += -Wno-maybe-uninitialized |
| endif |
| |
| endif |
| |
| # |
| # W=3 - more obscure warnings, can most likely be ignored |
| # |
| ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),) |
| |
| KBUILD_CFLAGS += -Wbad-function-cast |
| KBUILD_CFLAGS += -Wcast-align |
| KBUILD_CFLAGS += -Wcast-qual |
| KBUILD_CFLAGS += -Wconversion |
| KBUILD_CFLAGS += -Wpacked |
| KBUILD_CFLAGS += -Wpadded |
| KBUILD_CFLAGS += -Wpointer-arith |
| KBUILD_CFLAGS += -Wredundant-decls |
| KBUILD_CFLAGS += -Wsign-compare |
| KBUILD_CFLAGS += -Wswitch-default |
| |
| KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3 |
| |
| else |
| |
| # The following turn off the warnings enabled by -Wextra |
| KBUILD_CFLAGS += -Wno-sign-compare |
| KBUILD_CFLAGS += -Wno-unused-parameter |
| |
| endif |
| |
| # |
| # W=e and CONFIG_WERROR - error out on warnings |
| # |
| ifneq ($(findstring e, $(KBUILD_EXTRA_WARN))$(CONFIG_WERROR),) |
| |
| KBUILD_CPPFLAGS += -Werror |
| KBUILD_AFLAGS += -Wa,--fatal-warnings |
| KBUILD_LDFLAGS += --fatal-warnings |
| KBUILD_USERCFLAGS += -Werror |
| KBUILD_USERLDFLAGS += -Wl,--fatal-warnings |
| KBUILD_RUSTFLAGS += -Dwarnings |
| |
| # While hostprog flags are used during build bootstrapping (thus should not |
| # depend on CONFIG_ symbols), -Werror is disruptive and should be opted into. |
| # Only apply -Werror to hostprogs built after the initial Kconfig stage. |
| KBUILD_HOSTCFLAGS += -Werror |
| KBUILD_HOSTLDFLAGS += -Wl,--fatal-warnings |
| KBUILD_HOSTRUSTFLAGS += -Dwarnings |
| |
| endif |
