1 # SPDX-License-Identifier: GPL-2.0 1 # SPDX-License-Identifier: GPL-2.0
2 # ============================================ 2 # ==========================================================================
3 # make W=... settings 3 # make W=... settings
4 # 4 #
5 # There are four warning groups enabled by W=1 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 li 6 # They are independent, and can be combined like W=12 or W=123e.
7 # ============================================ 7 # ==========================================================================
8 8
9 # Default set of warnings, always enabled 9 # Default set of warnings, always enabled
10 KBUILD_CFLAGS += -Wall 10 KBUILD_CFLAGS += -Wall
11 KBUILD_CFLAGS += -Wundef 11 KBUILD_CFLAGS += -Wundef
12 KBUILD_CFLAGS += -Werror=implicit-function-dec 12 KBUILD_CFLAGS += -Werror=implicit-function-declaration
13 KBUILD_CFLAGS += -Werror=implicit-int 13 KBUILD_CFLAGS += -Werror=implicit-int
14 KBUILD_CFLAGS += -Werror=return-type 14 KBUILD_CFLAGS += -Werror=return-type
15 KBUILD_CFLAGS += -Werror=strict-prototypes 15 KBUILD_CFLAGS += -Werror=strict-prototypes
16 KBUILD_CFLAGS += -Wno-format-security 16 KBUILD_CFLAGS += -Wno-format-security
17 KBUILD_CFLAGS += -Wno-trigraphs 17 KBUILD_CFLAGS += -Wno-trigraphs
18 KBUILD_CFLAGS += $(call cc-disable-warning,fra 18 KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
19 KBUILD_CFLAGS += $(call cc-disable-warning, ad 19 KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
20 KBUILD_CFLAGS += -Wmissing-declarations <<
21 KBUILD_CFLAGS += -Wmissing-prototypes <<
22 20
23 ifneq ($(CONFIG_FRAME_WARN),0) 21 ifneq ($(CONFIG_FRAME_WARN),0)
24 KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_ 22 KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN)
25 endif 23 endif
26 24
27 KBUILD_CPPFLAGS-$(CONFIG_WERROR) += -Werror 25 KBUILD_CPPFLAGS-$(CONFIG_WERROR) += -Werror
28 KBUILD_CPPFLAGS += $(KBUILD_CPPFLAGS-y) 26 KBUILD_CPPFLAGS += $(KBUILD_CPPFLAGS-y)
29 KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += 27 KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
30 28
31 ifdef CONFIG_CC_IS_CLANG 29 ifdef CONFIG_CC_IS_CLANG
32 # The kernel builds with '-std=gnu11' so use o 30 # The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
33 KBUILD_CFLAGS += -Wno-gnu 31 KBUILD_CFLAGS += -Wno-gnu
34 else 32 else
35 33
36 # gcc inanely warns about local variables call 34 # gcc inanely warns about local variables called 'main'
37 KBUILD_CFLAGS += -Wno-main 35 KBUILD_CFLAGS += -Wno-main
38 endif 36 endif
39 37
>> 38 # These warnings generated too much noise in a regular build.
>> 39 # Use make W=1 to enable them (see scripts/Makefile.extrawarn)
>> 40 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
>> 41 KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
>> 42
40 # These result in bogus false positives 43 # These result in bogus false positives
41 KBUILD_CFLAGS += $(call cc-disable-warning, da 44 KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer)
42 45
43 # Variable Length Arrays (VLAs) should not be 46 # Variable Length Arrays (VLAs) should not be used anywhere in the kernel
44 KBUILD_CFLAGS += -Wvla 47 KBUILD_CFLAGS += -Wvla
45 48
46 # disable pointer signed / unsigned warnings i 49 # disable pointer signed / unsigned warnings in gcc 4.0
47 KBUILD_CFLAGS += -Wno-pointer-sign 50 KBUILD_CFLAGS += -Wno-pointer-sign
48 51
49 # In order to make sure new function cast mism 52 # In order to make sure new function cast mismatches are not introduced
50 # in the kernel (to avoid tripping CFI checkin 53 # in the kernel (to avoid tripping CFI checking), the kernel should be
51 # globally built with -Wcast-function-type. 54 # globally built with -Wcast-function-type.
52 KBUILD_CFLAGS += $(call cc-option, -Wcast-func 55 KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
53 56
54 # The allocators already balk at large sizes, 57 # The allocators already balk at large sizes, so silence the compiler
55 # warnings for bounds checks involving those p 58 # warnings for bounds checks involving those possible values. While
56 # -Wno-alloc-size-larger-than would normally b 59 # -Wno-alloc-size-larger-than would normally be used here, earlier versions
57 # of gcc (<9.1) weirdly don't handle the optio 60 # of gcc (<9.1) weirdly don't handle the option correctly when _other_
58 # warnings are produced (?!). Using -Walloc-si 61 # warnings are produced (?!). Using -Walloc-size-larger-than=SIZE_MAX
59 # doesn't work (as it is documented to), silen 62 # doesn't work (as it is documented to), silently resolving to "0" prior to
60 # version 9.1 (and producing an error more rec 63 # version 9.1 (and producing an error more recently). Numeric values larger
61 # than PTRDIFF_MAX also don't work prior to ve 64 # than PTRDIFF_MAX also don't work prior to version 9.1, which are silently
62 # ignored, continuing to default to PTRDIFF_MA 65 # ignored, continuing to default to PTRDIFF_MAX. So, left with no other
63 # choice, we must perform a versioned check to 66 # choice, we must perform a versioned check to disable this warning.
64 # https://lore.kernel.org/lkml/20210824115859. 67 # https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au
65 KBUILD_CFLAGS-$(call gcc-min-version, 90100) + 68 KBUILD_CFLAGS-$(call gcc-min-version, 90100) += -Wno-alloc-size-larger-than
66 KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_C 69 KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
67 70
68 # Prohibit date/time macros, which would make 71 # Prohibit date/time macros, which would make the build non-deterministic
69 KBUILD_CFLAGS += -Werror=date-time 72 KBUILD_CFLAGS += -Werror=date-time
70 73
71 # enforce correct pointer usage 74 # enforce correct pointer usage
72 KBUILD_CFLAGS += $(call cc-option,-Werror=inco 75 KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
73 76
74 # Require designated initializers for all mark 77 # Require designated initializers for all marked structures
75 KBUILD_CFLAGS += $(call cc-option,-Werror=desi 78 KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
76 79
77 # Warn if there is an enum types mismatch 80 # Warn if there is an enum types mismatch
78 KBUILD_CFLAGS += $(call cc-option,-Wenum-conve 81 KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion)
79 82
80 KBUILD_CFLAGS += -Wextra !! 83 # backward compatibility
81 KBUILD_CFLAGS += -Wunused !! 84 KBUILD_EXTRA_WARN ?= $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)
>> 85
>> 86 ifeq ("$(origin W)", "command line")
>> 87 KBUILD_EXTRA_WARN := $(W)
>> 88 endif
>> 89
>> 90 export KBUILD_EXTRA_WARN
82 91
83 # 92 #
84 # W=1 - warnings which may be relevant and do 93 # W=1 - warnings which may be relevant and do not occur too often
85 # 94 #
86 ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),) 95 ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
87 96
>> 97 KBUILD_CFLAGS += -Wextra -Wunused -Wno-unused-parameter
>> 98 KBUILD_CFLAGS += -Wmissing-declarations
>> 99 KBUILD_CFLAGS += $(call cc-option, -Wrestrict)
88 KBUILD_CFLAGS += -Wmissing-format-attribute 100 KBUILD_CFLAGS += -Wmissing-format-attribute
>> 101 KBUILD_CFLAGS += -Wmissing-prototypes
>> 102 KBUILD_CFLAGS += -Wold-style-definition
89 KBUILD_CFLAGS += -Wmissing-include-dirs 103 KBUILD_CFLAGS += -Wmissing-include-dirs
>> 104 KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable)
90 KBUILD_CFLAGS += $(call cc-option, -Wunused-co 105 KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
>> 106 KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned)
>> 107 KBUILD_CFLAGS += $(call cc-option, -Wformat-overflow)
>> 108 KBUILD_CFLAGS += $(call cc-option, -Wformat-truncation)
>> 109 KBUILD_CFLAGS += $(call cc-option, -Wstringop-overflow)
>> 110 KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
91 111
92 KBUILD_CPPFLAGS += -Wundef 112 KBUILD_CPPFLAGS += -Wundef
93 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1 113 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
94 114
95 else 115 else
96 116
97 # Some diagnostics enabled by default are nois 117 # Some diagnostics enabled by default are noisy.
98 # Suppress them by using -Wno... except for W= 118 # Suppress them by using -Wno... except for W=1.
99 KBUILD_CFLAGS += $(call cc-disable-warning, un 119 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
100 KBUILD_CFLAGS += $(call cc-disable-warning, un 120 KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
>> 121 KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
101 KBUILD_CFLAGS += $(call cc-disable-warning, pa 122 KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
102 KBUILD_CFLAGS += $(call cc-disable-warning, fo 123 KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
103 ifdef CONFIG_CC_IS_GCC <<
104 KBUILD_CFLAGS += $(call cc-disable-warning, fo 124 KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
105 else !! 125 KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow)
106 # Clang checks for overflow/truncation with '% <<
107 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id <<
108 KBUILD_CFLAGS += $(call cc-disable-warning, fo <<
109 KBUILD_CFLAGS += $(call cc-disable-warning, fo <<
110 endif <<
111 KBUILD_CFLAGS += $(call cc-disable-warning, st 126 KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
112 127
113 KBUILD_CFLAGS += -Wno-override-init # alias fo <<
114 <<
115 ifdef CONFIG_CC_IS_CLANG 128 ifdef CONFIG_CC_IS_CLANG
116 # Clang before clang-16 would warn on default 129 # Clang before clang-16 would warn on default argument promotions.
117 ifneq ($(call clang-min-version, 160000),y) 130 ifneq ($(call clang-min-version, 160000),y)
118 # Disable -Wformat 131 # Disable -Wformat
119 KBUILD_CFLAGS += -Wno-format 132 KBUILD_CFLAGS += -Wno-format
120 # Then re-enable flags that were part of the - 133 # Then re-enable flags that were part of the -Wformat group that aren't
121 # problematic. 134 # problematic.
122 KBUILD_CFLAGS += -Wformat-extra-args -Wformat- 135 KBUILD_CFLAGS += -Wformat-extra-args -Wformat-invalid-specifier
123 KBUILD_CFLAGS += -Wformat-zero-length -Wnonnul 136 KBUILD_CFLAGS += -Wformat-zero-length -Wnonnull
124 # Requires clang-12+. 137 # Requires clang-12+.
125 ifeq ($(call clang-min-version, 120000),y) 138 ifeq ($(call clang-min-version, 120000),y)
126 KBUILD_CFLAGS += -Wformat-insufficient-args 139 KBUILD_CFLAGS += -Wformat-insufficient-args
127 endif 140 endif
128 endif 141 endif
129 KBUILD_CFLAGS += $(call cc-disable-warning, po 142 KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
130 KBUILD_CFLAGS += -Wno-tautological-constant-ou 143 KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
131 KBUILD_CFLAGS += $(call cc-disable-warning, un 144 KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access)
>> 145 KBUILD_CFLAGS += $(call cc-disable-warning, cast-function-type-strict)
132 KBUILD_CFLAGS += -Wno-enum-compare-conditional 146 KBUILD_CFLAGS += -Wno-enum-compare-conditional
133 KBUILD_CFLAGS += -Wno-enum-enum-conversion 147 KBUILD_CFLAGS += -Wno-enum-enum-conversion
134 endif 148 endif
135 149
136 endif 150 endif
137 151
138 # 152 #
139 # W=2 - warnings which occur quite often but m 153 # W=2 - warnings which occur quite often but may still be relevant
140 # 154 #
141 ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),) 155 ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
142 156
143 KBUILD_CFLAGS += -Wdisabled-optimization 157 KBUILD_CFLAGS += -Wdisabled-optimization
144 KBUILD_CFLAGS += -Wshadow 158 KBUILD_CFLAGS += -Wshadow
145 KBUILD_CFLAGS += $(call cc-option, -Wlogical-o 159 KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
>> 160 KBUILD_CFLAGS += -Wmissing-field-initializers
>> 161 KBUILD_CFLAGS += -Wtype-limits
>> 162 KBUILD_CFLAGS += $(call cc-option, -Wmaybe-uninitialized)
146 KBUILD_CFLAGS += $(call cc-option, -Wunused-ma 163 KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
147 164
>> 165 ifdef CONFIG_CC_IS_CLANG
>> 166 KBUILD_CFLAGS += -Winitializer-overrides
>> 167 endif
>> 168
148 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2 169 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2
149 170
150 else 171 else
151 172
152 # The following turn off the warnings enabled 173 # The following turn off the warnings enabled by -Wextra
153 KBUILD_CFLAGS += -Wno-missing-field-initialize 174 KBUILD_CFLAGS += -Wno-missing-field-initializers
154 KBUILD_CFLAGS += -Wno-type-limits 175 KBUILD_CFLAGS += -Wno-type-limits
155 KBUILD_CFLAGS += -Wno-shift-negative-value 176 KBUILD_CFLAGS += -Wno-shift-negative-value
156 177
157 ifdef CONFIG_CC_IS_GCC !! 178 ifdef CONFIG_CC_IS_CLANG
>> 179 KBUILD_CFLAGS += -Wno-initializer-overrides
>> 180 else
158 KBUILD_CFLAGS += -Wno-maybe-uninitialized 181 KBUILD_CFLAGS += -Wno-maybe-uninitialized
159 endif 182 endif
160 183
161 endif 184 endif
162 185
163 # 186 #
164 # W=3 - more obscure warnings, can most likely 187 # W=3 - more obscure warnings, can most likely be ignored
165 # 188 #
166 ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),) 189 ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
167 190
168 KBUILD_CFLAGS += -Wbad-function-cast 191 KBUILD_CFLAGS += -Wbad-function-cast
169 KBUILD_CFLAGS += -Wcast-align 192 KBUILD_CFLAGS += -Wcast-align
170 KBUILD_CFLAGS += -Wcast-qual 193 KBUILD_CFLAGS += -Wcast-qual
171 KBUILD_CFLAGS += -Wconversion 194 KBUILD_CFLAGS += -Wconversion
172 KBUILD_CFLAGS += -Wpacked 195 KBUILD_CFLAGS += -Wpacked
173 KBUILD_CFLAGS += -Wpadded 196 KBUILD_CFLAGS += -Wpadded
174 KBUILD_CFLAGS += -Wpointer-arith 197 KBUILD_CFLAGS += -Wpointer-arith
175 KBUILD_CFLAGS += -Wredundant-decls 198 KBUILD_CFLAGS += -Wredundant-decls
176 KBUILD_CFLAGS += -Wsign-compare 199 KBUILD_CFLAGS += -Wsign-compare
177 KBUILD_CFLAGS += -Wswitch-default 200 KBUILD_CFLAGS += -Wswitch-default
>> 201 KBUILD_CFLAGS += $(call cc-option, -Wpacked-bitfield-compat)
178 202
179 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3 203 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
180 204
181 else 205 else
182 206
183 # The following turn off the warnings enabled 207 # The following turn off the warnings enabled by -Wextra
184 KBUILD_CFLAGS += -Wno-sign-compare 208 KBUILD_CFLAGS += -Wno-sign-compare
185 KBUILD_CFLAGS += -Wno-unused-parameter <<
186 209
187 endif 210 endif
188 211
189 # 212 #
190 # W=e - error out on warnings 213 # W=e - error out on warnings
191 # 214 #
192 ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),) 215 ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
193 216
194 KBUILD_CFLAGS += -Werror 217 KBUILD_CFLAGS += -Werror
195 218
196 endif 219 endif
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