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 += $(call cc-disable-warning, address-of-packed-member)
20 KBUILD_CFLAGS += -Wmissing-declarations 20 KBUILD_CFLAGS += -Wmissing-declarations
21 KBUILD_CFLAGS += -Wmissing-prototypes 21 KBUILD_CFLAGS += -Wmissing-prototypes
22 22
23 ifneq ($(CONFIG_FRAME_WARN),0) 23 ifneq ($(CONFIG_FRAME_WARN),0)
24 KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_ 24 KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN)
25 endif 25 endif
26 26
27 KBUILD_CPPFLAGS-$(CONFIG_WERROR) += -Werror 27 KBUILD_CPPFLAGS-$(CONFIG_WERROR) += -Werror
28 KBUILD_CPPFLAGS += $(KBUILD_CPPFLAGS-y) 28 KBUILD_CPPFLAGS += $(KBUILD_CPPFLAGS-y)
29 KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += 29 KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
30 30
31 ifdef CONFIG_CC_IS_CLANG 31 ifdef CONFIG_CC_IS_CLANG
32 # The kernel builds with '-std=gnu11' so use o 32 # The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
33 KBUILD_CFLAGS += -Wno-gnu 33 KBUILD_CFLAGS += -Wno-gnu
34 else 34 else
35 35
36 # gcc inanely warns about local variables call 36 # gcc inanely warns about local variables called 'main'
37 KBUILD_CFLAGS += -Wno-main 37 KBUILD_CFLAGS += -Wno-main
38 endif 38 endif
39 39
40 # These result in bogus false positives 40 # These result in bogus false positives
41 KBUILD_CFLAGS += $(call cc-disable-warning, da 41 KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer)
42 42
43 # Variable Length Arrays (VLAs) should not be 43 # Variable Length Arrays (VLAs) should not be used anywhere in the kernel
44 KBUILD_CFLAGS += -Wvla 44 KBUILD_CFLAGS += -Wvla
45 45
46 # disable pointer signed / unsigned warnings i 46 # disable pointer signed / unsigned warnings in gcc 4.0
47 KBUILD_CFLAGS += -Wno-pointer-sign 47 KBUILD_CFLAGS += -Wno-pointer-sign
48 48
49 # In order to make sure new function cast mism 49 # In order to make sure new function cast mismatches are not introduced
50 # in the kernel (to avoid tripping CFI checkin 50 # in the kernel (to avoid tripping CFI checking), the kernel should be
51 # globally built with -Wcast-function-type. 51 # globally built with -Wcast-function-type.
52 KBUILD_CFLAGS += $(call cc-option, -Wcast-func 52 KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
53 53
54 # The allocators already balk at large sizes, 54 # The allocators already balk at large sizes, so silence the compiler
55 # warnings for bounds checks involving those p 55 # warnings for bounds checks involving those possible values. While
56 # -Wno-alloc-size-larger-than would normally b 56 # -Wno-alloc-size-larger-than would normally be used here, earlier versions
57 # of gcc (<9.1) weirdly don't handle the optio 57 # of gcc (<9.1) weirdly don't handle the option correctly when _other_
58 # warnings are produced (?!). Using -Walloc-si 58 # warnings are produced (?!). Using -Walloc-size-larger-than=SIZE_MAX
59 # doesn't work (as it is documented to), silen 59 # doesn't work (as it is documented to), silently resolving to "0" prior to
60 # version 9.1 (and producing an error more rec 60 # version 9.1 (and producing an error more recently). Numeric values larger
61 # than PTRDIFF_MAX also don't work prior to ve 61 # than PTRDIFF_MAX also don't work prior to version 9.1, which are silently
62 # ignored, continuing to default to PTRDIFF_MA 62 # ignored, continuing to default to PTRDIFF_MAX. So, left with no other
63 # choice, we must perform a versioned check to 63 # choice, we must perform a versioned check to disable this warning.
64 # https://lore.kernel.org/lkml/20210824115859. 64 # https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au
65 KBUILD_CFLAGS-$(call gcc-min-version, 90100) + 65 KBUILD_CFLAGS-$(call gcc-min-version, 90100) += -Wno-alloc-size-larger-than
66 KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_C 66 KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
67 67
68 # Prohibit date/time macros, which would make 68 # Prohibit date/time macros, which would make the build non-deterministic
69 KBUILD_CFLAGS += -Werror=date-time 69 KBUILD_CFLAGS += -Werror=date-time
70 70
71 # enforce correct pointer usage 71 # enforce correct pointer usage
72 KBUILD_CFLAGS += $(call cc-option,-Werror=inco 72 KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
73 73
74 # Require designated initializers for all mark 74 # Require designated initializers for all marked structures
75 KBUILD_CFLAGS += $(call cc-option,-Werror=desi 75 KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
76 76
77 # Warn if there is an enum types mismatch 77 # Warn if there is an enum types mismatch
78 KBUILD_CFLAGS += $(call cc-option,-Wenum-conve 78 KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion)
79 79
80 KBUILD_CFLAGS += -Wextra 80 KBUILD_CFLAGS += -Wextra
81 KBUILD_CFLAGS += -Wunused 81 KBUILD_CFLAGS += -Wunused
82 82
83 # 83 #
84 # W=1 - warnings which may be relevant and do 84 # W=1 - warnings which may be relevant and do not occur too often
85 # 85 #
86 ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),) 86 ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
87 87
88 KBUILD_CFLAGS += -Wmissing-format-attribute 88 KBUILD_CFLAGS += -Wmissing-format-attribute
89 KBUILD_CFLAGS += -Wmissing-include-dirs 89 KBUILD_CFLAGS += -Wmissing-include-dirs
90 KBUILD_CFLAGS += $(call cc-option, -Wunused-co 90 KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
91 91
92 KBUILD_CPPFLAGS += -Wundef 92 KBUILD_CPPFLAGS += -Wundef
93 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1 93 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
94 94
95 else 95 else
96 96
97 # Some diagnostics enabled by default are nois 97 # Some diagnostics enabled by default are noisy.
98 # Suppress them by using -Wno... except for W= 98 # Suppress them by using -Wno... except for W=1.
99 KBUILD_CFLAGS += $(call cc-disable-warning, un 99 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
100 KBUILD_CFLAGS += $(call cc-disable-warning, un 100 KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
101 KBUILD_CFLAGS += $(call cc-disable-warning, pa 101 KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
102 KBUILD_CFLAGS += $(call cc-disable-warning, fo 102 KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
103 ifdef CONFIG_CC_IS_GCC 103 ifdef CONFIG_CC_IS_GCC
104 KBUILD_CFLAGS += $(call cc-disable-warning, fo 104 KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
105 else 105 else
106 # Clang checks for overflow/truncation with '% 106 # Clang checks for overflow/truncation with '%p', while GCC does not:
107 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id 107 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111219
108 KBUILD_CFLAGS += $(call cc-disable-warning, fo 108 KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow-non-kprintf)
109 KBUILD_CFLAGS += $(call cc-disable-warning, fo 109 KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation-non-kprintf)
110 endif 110 endif
111 KBUILD_CFLAGS += $(call cc-disable-warning, st 111 KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
112 112
113 KBUILD_CFLAGS += -Wno-override-init # alias fo 113 KBUILD_CFLAGS += -Wno-override-init # alias for -Wno-initializer-overrides in clang
114 114
115 ifdef CONFIG_CC_IS_CLANG 115 ifdef CONFIG_CC_IS_CLANG
116 # Clang before clang-16 would warn on default 116 # Clang before clang-16 would warn on default argument promotions.
117 ifneq ($(call clang-min-version, 160000),y) 117 ifneq ($(call clang-min-version, 160000),y)
118 # Disable -Wformat 118 # Disable -Wformat
119 KBUILD_CFLAGS += -Wno-format 119 KBUILD_CFLAGS += -Wno-format
120 # Then re-enable flags that were part of the - 120 # Then re-enable flags that were part of the -Wformat group that aren't
121 # problematic. 121 # problematic.
122 KBUILD_CFLAGS += -Wformat-extra-args -Wformat- 122 KBUILD_CFLAGS += -Wformat-extra-args -Wformat-invalid-specifier
123 KBUILD_CFLAGS += -Wformat-zero-length -Wnonnul 123 KBUILD_CFLAGS += -Wformat-zero-length -Wnonnull
124 # Requires clang-12+. 124 # Requires clang-12+.
125 ifeq ($(call clang-min-version, 120000),y) 125 ifeq ($(call clang-min-version, 120000),y)
126 KBUILD_CFLAGS += -Wformat-insufficient-args 126 KBUILD_CFLAGS += -Wformat-insufficient-args
127 endif 127 endif
128 endif 128 endif
129 KBUILD_CFLAGS += $(call cc-disable-warning, po 129 KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
130 KBUILD_CFLAGS += -Wno-tautological-constant-ou 130 KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
131 KBUILD_CFLAGS += $(call cc-disable-warning, un 131 KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access)
132 KBUILD_CFLAGS += -Wno-enum-compare-conditional 132 KBUILD_CFLAGS += -Wno-enum-compare-conditional
133 KBUILD_CFLAGS += -Wno-enum-enum-conversion 133 KBUILD_CFLAGS += -Wno-enum-enum-conversion
134 endif 134 endif
135 135
136 endif 136 endif
137 137
138 # 138 #
139 # W=2 - warnings which occur quite often but m 139 # W=2 - warnings which occur quite often but may still be relevant
140 # 140 #
141 ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),) 141 ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
142 142
143 KBUILD_CFLAGS += -Wdisabled-optimization 143 KBUILD_CFLAGS += -Wdisabled-optimization
144 KBUILD_CFLAGS += -Wshadow 144 KBUILD_CFLAGS += -Wshadow
145 KBUILD_CFLAGS += $(call cc-option, -Wlogical-o 145 KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
146 KBUILD_CFLAGS += $(call cc-option, -Wunused-ma 146 KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
147 147
148 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2 148 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2
149 149
150 else 150 else
151 151
152 # The following turn off the warnings enabled 152 # The following turn off the warnings enabled by -Wextra
153 KBUILD_CFLAGS += -Wno-missing-field-initialize 153 KBUILD_CFLAGS += -Wno-missing-field-initializers
154 KBUILD_CFLAGS += -Wno-type-limits 154 KBUILD_CFLAGS += -Wno-type-limits
155 KBUILD_CFLAGS += -Wno-shift-negative-value 155 KBUILD_CFLAGS += -Wno-shift-negative-value
156 156
157 ifdef CONFIG_CC_IS_GCC 157 ifdef CONFIG_CC_IS_GCC
158 KBUILD_CFLAGS += -Wno-maybe-uninitialized 158 KBUILD_CFLAGS += -Wno-maybe-uninitialized
159 endif 159 endif
160 160
161 endif 161 endif
162 162
163 # 163 #
164 # W=3 - more obscure warnings, can most likely 164 # W=3 - more obscure warnings, can most likely be ignored
165 # 165 #
166 ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),) 166 ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
167 167
168 KBUILD_CFLAGS += -Wbad-function-cast 168 KBUILD_CFLAGS += -Wbad-function-cast
169 KBUILD_CFLAGS += -Wcast-align 169 KBUILD_CFLAGS += -Wcast-align
170 KBUILD_CFLAGS += -Wcast-qual 170 KBUILD_CFLAGS += -Wcast-qual
171 KBUILD_CFLAGS += -Wconversion 171 KBUILD_CFLAGS += -Wconversion
172 KBUILD_CFLAGS += -Wpacked 172 KBUILD_CFLAGS += -Wpacked
173 KBUILD_CFLAGS += -Wpadded 173 KBUILD_CFLAGS += -Wpadded
174 KBUILD_CFLAGS += -Wpointer-arith 174 KBUILD_CFLAGS += -Wpointer-arith
175 KBUILD_CFLAGS += -Wredundant-decls 175 KBUILD_CFLAGS += -Wredundant-decls
176 KBUILD_CFLAGS += -Wsign-compare 176 KBUILD_CFLAGS += -Wsign-compare
177 KBUILD_CFLAGS += -Wswitch-default 177 KBUILD_CFLAGS += -Wswitch-default
178 178
179 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3 179 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
180 180
181 else 181 else
182 182
183 # The following turn off the warnings enabled 183 # The following turn off the warnings enabled by -Wextra
184 KBUILD_CFLAGS += -Wno-sign-compare 184 KBUILD_CFLAGS += -Wno-sign-compare
185 KBUILD_CFLAGS += -Wno-unused-parameter 185 KBUILD_CFLAGS += -Wno-unused-parameter
186 186
187 endif 187 endif
188 188
189 # 189 #
190 # W=e - error out on warnings 190 # W=e - error out on warnings
191 # 191 #
192 ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),) 192 ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
193 193
194 KBUILD_CFLAGS += -Werror 194 KBUILD_CFLAGS += -Werror
195 195
196 endif 196 endif
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