1# SPDX-License-Identifier: GPL-2.0
 2# ==========================================================================
 3# make W=... settings
 4#
 5# There are three warning groups enabled by W=1, W=2, W=3.
 6# They are independent, and can be combined like W=12 or W=123.
 7# ==========================================================================
 8
 9KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
 
 
 
 
 
 
 
 
 
 
 
 
10
11# backward compatibility
12KBUILD_EXTRA_WARN ?= $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)
 
13
14ifeq ("$(origin W)", "command line")
15  KBUILD_EXTRA_WARN := $(W)
 
 
 
 
 
 
 
 
 
16endif
17
18export KBUILD_EXTRA_WARN
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
19
20#
21# W=1 - warnings which may be relevant and do not occur too often
22#
23ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
24
25KBUILD_CFLAGS += -Wextra -Wunused -Wno-unused-parameter
26KBUILD_CFLAGS += -Wmissing-declarations
27KBUILD_CFLAGS += -Wmissing-format-attribute
28KBUILD_CFLAGS += -Wmissing-prototypes
29KBUILD_CFLAGS += -Wold-style-definition
30KBUILD_CFLAGS += -Wmissing-include-dirs
31KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable)
32KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
33KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned)
 
 
34KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
35# The following turn off the warnings enabled by -Wextra
36KBUILD_CFLAGS += -Wno-missing-field-initializers
37KBUILD_CFLAGS += -Wno-sign-compare
38
 
39KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
40
41else
42
43# Some diagnostics enabled by default are noisy.
44# Suppress them by using -Wno... except for W=1.
 
 
 
 
 
 
 
45
46ifdef CONFIG_CC_IS_CLANG
47KBUILD_CFLAGS += -Wno-initializer-overrides
 
 
48KBUILD_CFLAGS += -Wno-format
49KBUILD_CFLAGS += -Wno-sign-compare
50KBUILD_CFLAGS += -Wno-format-zero-length
 
 
 
 
 
 
 
 
 
 
 
51endif
52
53endif
54
55#
56# W=2 - warnings which occur quite often but may still be relevant
57#
58ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
59
60KBUILD_CFLAGS += -Wcast-align
61KBUILD_CFLAGS += -Wdisabled-optimization
62KBUILD_CFLAGS += -Wnested-externs
63KBUILD_CFLAGS += -Wshadow
64KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
65KBUILD_CFLAGS += -Wmissing-field-initializers
66KBUILD_CFLAGS += -Wsign-compare
67KBUILD_CFLAGS += $(call cc-option, -Wmaybe-uninitialized)
68KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
69
 
 
 
 
70KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2
71
 
 
 
 
 
 
 
 
 
 
 
 
 
72endif
73
74#
75# W=3 - more obscure warnings, can most likely be ignored
76#
77ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
78
79KBUILD_CFLAGS += -Wbad-function-cast
 
80KBUILD_CFLAGS += -Wcast-qual
81KBUILD_CFLAGS += -Wconversion
82KBUILD_CFLAGS += -Wpacked
83KBUILD_CFLAGS += -Wpadded
84KBUILD_CFLAGS += -Wpointer-arith
85KBUILD_CFLAGS += -Wredundant-decls
 
86KBUILD_CFLAGS += -Wswitch-default
87KBUILD_CFLAGS += $(call cc-option, -Wpacked-bitfield-compat)
88
89KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
 
 
 
 
 
 
 
 
 
 
 
 
 
 
90
91endif

  1# SPDX-License-Identifier: GPL-2.0
  2# ==========================================================================
  3# make W=... settings
  4#
  5# There are four warning groups enabled by W=1, W=2, W=3, and W=e
  6# They are independent, and can be combined like W=12 or W=123e.
  7# ==========================================================================
  8
  9# Default set of warnings, always enabled
 10KBUILD_CFLAGS += -Wall
 11KBUILD_CFLAGS += -Wundef
 12KBUILD_CFLAGS += -Werror=implicit-function-declaration
 13KBUILD_CFLAGS += -Werror=implicit-int
 14KBUILD_CFLAGS += -Werror=return-type
 15KBUILD_CFLAGS += -Werror=strict-prototypes
 16KBUILD_CFLAGS += -Wno-format-security
 17KBUILD_CFLAGS += -Wno-trigraphs
 18KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
 19KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
 20KBUILD_CFLAGS += -Wmissing-declarations
 21KBUILD_CFLAGS += -Wmissing-prototypes
 22
 23ifneq ($(CONFIG_FRAME_WARN),0)
 24KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN)
 25endif
 26
 27KBUILD_CPPFLAGS-$(CONFIG_WERROR) += -Werror
 28KBUILD_CPPFLAGS += $(KBUILD_CPPFLAGS-y)
 29KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
 30
 31ifdef CONFIG_CC_IS_CLANG
 32# The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
 33KBUILD_CFLAGS += -Wno-gnu
 34else
 35
 36# gcc inanely warns about local variables called 'main'
 37KBUILD_CFLAGS += -Wno-main
 38endif
 39
 40# These warnings generated too much noise in a regular build.
 41# Use make W=1 to enable them (see scripts/Makefile.extrawarn)
 42KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
 43KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
 44
 45# These result in bogus false positives
 46KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer)
 47
 48# Variable Length Arrays (VLAs) should not be used anywhere in the kernel
 49KBUILD_CFLAGS += -Wvla
 50
 51# disable pointer signed / unsigned warnings in gcc 4.0
 52KBUILD_CFLAGS += -Wno-pointer-sign
 53
 54# In order to make sure new function cast mismatches are not introduced
 55# in the kernel (to avoid tripping CFI checking), the kernel should be
 56# globally built with -Wcast-function-type.
 57KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
 58
 59# The allocators already balk at large sizes, so silence the compiler
 60# warnings for bounds checks involving those possible values. While
 61# -Wno-alloc-size-larger-than would normally be used here, earlier versions
 62# of gcc (<9.1) weirdly don't handle the option correctly when _other_
 63# warnings are produced (?!). Using -Walloc-size-larger-than=SIZE_MAX
 64# doesn't work (as it is documented to), silently resolving to "0" prior to
 65# version 9.1 (and producing an error more recently). Numeric values larger
 66# than PTRDIFF_MAX also don't work prior to version 9.1, which are silently
 67# ignored, continuing to default to PTRDIFF_MAX. So, left with no other
 68# choice, we must perform a versioned check to disable this warning.
 69# https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au
 70KBUILD_CFLAGS-$(call gcc-min-version, 90100) += -Wno-alloc-size-larger-than
 71KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
 72
 73# Prohibit date/time macros, which would make the build non-deterministic
 74KBUILD_CFLAGS += -Werror=date-time
 75
 76# enforce correct pointer usage
 77KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
 78
 79# Require designated initializers for all marked structures
 80KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
 81
 82# Warn if there is an enum types mismatch
 83KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion)
 84
 85#
 86# W=1 - warnings which may be relevant and do not occur too often
 87#
 88ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
 89
 90KBUILD_CFLAGS += -Wextra -Wunused -Wno-unused-parameter
 91KBUILD_CFLAGS += $(call cc-option, -Wrestrict)
 92KBUILD_CFLAGS += -Wmissing-format-attribute
 
 93KBUILD_CFLAGS += -Wold-style-definition
 94KBUILD_CFLAGS += -Wmissing-include-dirs
 95KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable)
 96KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
 97KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned)
 98KBUILD_CFLAGS += $(call cc-option, -Wformat-overflow)
 99KBUILD_CFLAGS += $(call cc-option, -Wformat-truncation)
100KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
 
 
 
101
102KBUILD_CPPFLAGS += -Wundef
103KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
104
105else
106
107# Some diagnostics enabled by default are noisy.
108# Suppress them by using -Wno... except for W=1.
109KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
110KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
111KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
112KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
113KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
114KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
115KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
116
117ifdef CONFIG_CC_IS_CLANG
118# Clang before clang-16 would warn on default argument promotions.
119ifneq ($(call clang-min-version, 160000),y)
120# Disable -Wformat
121KBUILD_CFLAGS += -Wno-format
122# Then re-enable flags that were part of the -Wformat group that aren't
123# problematic.
124KBUILD_CFLAGS += -Wformat-extra-args -Wformat-invalid-specifier
125KBUILD_CFLAGS += -Wformat-zero-length -Wnonnull
126# Requires clang-12+.
127ifeq ($(call clang-min-version, 120000),y)
128KBUILD_CFLAGS += -Wformat-insufficient-args
129endif
130endif
131KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
132KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
133KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access)
134KBUILD_CFLAGS += $(call cc-disable-warning, cast-function-type-strict)
135endif
136
137endif
138
139#
140# W=2 - warnings which occur quite often but may still be relevant
141#
142ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
143
 
144KBUILD_CFLAGS += -Wdisabled-optimization
 
145KBUILD_CFLAGS += -Wshadow
146KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
147KBUILD_CFLAGS += -Wmissing-field-initializers
148KBUILD_CFLAGS += -Wtype-limits
149KBUILD_CFLAGS += $(call cc-option, -Wmaybe-uninitialized)
150KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
151
152ifdef CONFIG_CC_IS_CLANG
153KBUILD_CFLAGS += -Winitializer-overrides
154endif
155
156KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2
157
158else
159
160# The following turn off the warnings enabled by -Wextra
161KBUILD_CFLAGS += -Wno-missing-field-initializers
162KBUILD_CFLAGS += -Wno-type-limits
163KBUILD_CFLAGS += -Wno-shift-negative-value
164
165ifdef CONFIG_CC_IS_CLANG
166KBUILD_CFLAGS += -Wno-initializer-overrides
167else
168KBUILD_CFLAGS += -Wno-maybe-uninitialized
169endif
170
171endif
172
173#
174# W=3 - more obscure warnings, can most likely be ignored
175#
176ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
177
178KBUILD_CFLAGS += -Wbad-function-cast
179KBUILD_CFLAGS += -Wcast-align
180KBUILD_CFLAGS += -Wcast-qual
181KBUILD_CFLAGS += -Wconversion
182KBUILD_CFLAGS += -Wpacked
183KBUILD_CFLAGS += -Wpadded
184KBUILD_CFLAGS += -Wpointer-arith
185KBUILD_CFLAGS += -Wredundant-decls
186KBUILD_CFLAGS += -Wsign-compare
187KBUILD_CFLAGS += -Wswitch-default
188KBUILD_CFLAGS += $(call cc-option, -Wpacked-bitfield-compat)
189
190KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
191
192else
193
194# The following turn off the warnings enabled by -Wextra
195KBUILD_CFLAGS += -Wno-sign-compare
196
197endif
198
199#
200# W=e - error out on warnings
201#
202ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
203
204KBUILD_CFLAGS += -Werror
205
206endif