sys/conf/kern.mk

   1 # $FreeBSD$
   2
   3 #
   4 # Warning flags for compiling the kernel and components of the kernel:
   5 #
   6 CWARNFLAGS?=    -Wall -Wstrict-prototypes \
   7                 -Wmissing-prototypes -Wpointer-arith -Wcast-qual \
   8                 -Wundef -Wno-pointer-sign ${FORMAT_EXTENSIONS} \
   9                 -Wmissing-include-dirs -fdiagnostics-show-option \
  10                 -Wno-unknown-pragmas \
  11                 ${CWARNEXTRA}
  12 #
  13 # The following flags are next up for working on:
  14 #       -Wextra
  15
  16 # Disable a few warnings for clang, since there are several places in the
  17 # kernel where fixing them is more trouble than it is worth, or where there is
  18 # a false positive.
  19 .if ${COMPILER_TYPE} == "clang"
  20 NO_WCONSTANT_CONVERSION=        -Wno-error=constant-conversion
  21 NO_WSHIFT_COUNT_NEGATIVE=       -Wno-shift-count-negative
  22 NO_WSHIFT_COUNT_OVERFLOW=       -Wno-shift-count-overflow
  23 NO_WSELF_ASSIGN=                -Wno-self-assign
  24 NO_WUNNEEDED_INTERNAL_DECL=     -Wno-error=unneeded-internal-declaration
  25 NO_WSOMETIMES_UNINITIALIZED=    -Wno-error=sometimes-uninitialized
  26 NO_WCAST_QUAL=                  -Wno-error=cast-qual
  27 NO_WTAUTOLOGICAL_POINTER_COMPARE= -Wno-tautological-pointer-compare
  28 .if ${COMPILER_VERSION} >= 100000
  29 NO_WMISLEADING_INDENTATION=     -Wno-misleading-indentation
  30 .endif
  31 .if ${COMPILER_VERSION} >= 130000
  32 NO_WUNUSED_BUT_SET_VARIABLE=    -Wno-unused-but-set-variable
  33 .endif
  34 .if ${COMPILER_VERSION} >= 140000
  35 NO_WBITWISE_INSTEAD_OF_LOGICAL= -Wno-bitwise-instead-of-logical
  36 .endif
  37 .if ${COMPILER_VERSION} >= 150000
  38 NO_WSTRICT_PROTOTYPES=          -Wno-strict-prototypes
  39 NO_WDEPRECATED_NON_PROTOTYPE=   -Wno-deprecated-non-prototype
  40 .endif
  41 # Several other warnings which might be useful in some cases, but not severe
  42 # enough to error out the whole kernel build.  Display them anyway, so there is
  43 # some incentive to fix them eventually.
  44 CWARNEXTRA?=    -Wno-error=tautological-compare -Wno-error=empty-body \
  45                 -Wno-error=parentheses-equality -Wno-error=unused-function \
  46                 -Wno-error=pointer-sign
  47 CWARNEXTRA+=    -Wno-error=shift-negative-value
  48 CWARNEXTRA+=    -Wno-address-of-packed-member
  49 .if ${COMPILER_VERSION} >= 150000
  50 # Clang 15 has much more aggressive diagnostics about K&R prototypes,
  51 # mismatched prototypes, and unused-but-set variables. Make these
  52 # non-fatal for the time being.
  53 CWARNEXTRA+=    -Wno-error=deprecated-non-prototype
  54 CWARNEXTRA+=    -Wno-error=strict-prototypes
  55 CWARNEXTRA+=    -Wno-error=unused-but-set-variable
  56 .endif
  57 .endif  # clang
  58
  59 .if ${COMPILER_TYPE} == "gcc"
  60 # Catch-all for all the things that are in our tree, but for which we're
  61 # not yet ready for this compiler.
  62 NO_WUNUSED_BUT_SET_VARIABLE=-Wno-unused-but-set-variable
  63 CWARNEXTRA?=    -Wno-error=address                              \
  64                 -Wno-error=aggressive-loop-optimizations        \
  65                 -Wno-error=array-bounds                         \
  66                 -Wno-error=attributes                           \
  67                 -Wno-error=cast-qual                            \
  68                 -Wno-error=enum-compare                         \
  69                 -Wno-error=maybe-uninitialized                  \
  70                 -Wno-error=misleading-indentation               \
  71                 -Wno-error=nonnull-compare                      \
  72                 -Wno-error=overflow                             \
  73                 -Wno-error=sequence-point                       \
  74                 -Wno-error=shift-overflow                       \
  75                 -Wno-error=tautological-compare                 \
  76                 -Wno-error=unused-function
  77 .if ${COMPILER_VERSION} >= 70100
  78 CWARNEXTRA+=    -Wno-error=stringop-overflow
  79 .endif
  80 .if ${COMPILER_VERSION} >= 70200
  81 CWARNEXTRA+=    -Wno-error=memset-elt-size
  82 .endif
  83 .if ${COMPILER_VERSION} >= 80000
  84 CWARNEXTRA+=    -Wno-error=packed-not-aligned
  85 .endif
  86 .if ${COMPILER_VERSION} >= 90100
  87 CWARNEXTRA+=    -Wno-address-of-packed-member                   \
  88                 -Wno-error=alloca-larger-than=
  89 .if ${COMPILER_VERSION} >= 120100
  90 CWARNEXTRA+=    -Wno-error=nonnull                              \
  91                 -Wno-dangling-pointer                           \
  92                 -Wno-zero-length-bounds
  93 NO_WINFINITE_RECURSION= -Wno-infinite-recursion
  94 NO_WSTRINGOP_OVERREAD=  -Wno-stringop-overread
  95 .endif
  96 .endif
  97
  98 # GCC produces false positives for functions that switch on an
  99 # enum (GCC bug 87950)
 100 CWARNFLAGS+=    -Wno-return-type
 101 .endif  # gcc
 102
 103 # This warning is utter nonsense
 104 CWARNFLAGS+=    -Wno-format-zero-length
 105
 106 # External compilers may not support our format extensions.  Allow them
 107 # to be disabled.  WARNING: format checking is disabled in this case.
 108 .if ${MK_FORMAT_EXTENSIONS} == "no"
 109 FORMAT_EXTENSIONS=      -Wno-format
 110 .elif ${COMPILER_TYPE} == "clang" || \
 111     (${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 120100)
 112 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
 113 .else
 114 FORMAT_EXTENSIONS=      -fformat-extensions
 115 .endif
 116
 117 #
 118 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
 119 # and above adds code to the entry and exit point of every function to align the
 120 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
 121 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
 122 # it is probably an overall loss as it makes the code bigger (less efficient
 123 # use of code cache tag lines) and uses more stack (less efficient use of data
 124 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
 125 # operations inside the kernel itself.  These operations are exclusively
 126 # reserved for user applications.
 127 #
 128 # gcc:
 129 # Setting -mno-mmx implies -mno-3dnow
 130 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
 131 #
 132 # clang:
 133 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 134 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 135 #
 136 .if ${MACHINE_CPUARCH} == "i386"
 137 CFLAGS.gcc+=    -mpreferred-stack-boundary=2
 138 CFLAGS.clang+=  -mno-aes -mno-avx
 139 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 140 INLINE_LIMIT?=  8000
 141 .endif
 142
 143 .if ${MACHINE_CPUARCH} == "arm"
 144 INLINE_LIMIT?=  8000
 145 .endif
 146
 147 .if ${MACHINE_CPUARCH} == "aarch64"
 148 # We generally don't want fpu instructions in the kernel.
 149 CFLAGS += -mgeneral-regs-only
 150 # Reserve x18 for pcpu data
 151 CFLAGS += -ffixed-x18
 152 INLINE_LIMIT?=  8000
 153 .endif
 154
 155 #
 156 # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating
 157 # point registers within the kernel. However, for kernels supporting hardware
 158 # float (FPE), we have to include that in the march so we can have limited
 159 # floating point support in context switching needed for that. This is different
 160 # than userland where we use a hard-float ABI (lp64d).
 161 #
 162 # We also specify the "medium" code model, which generates code suitable for a
 163 # 2GiB addressing range located at any offset, allowing modules to be located
 164 # anywhere in the 64-bit address space.  Note that clang and GCC refer to this
 165 # code model as "medium" and "medany" respectively.
 166 #
 167 .if ${MACHINE_CPUARCH} == "riscv"
 168 CFLAGS+=        -march=rv64imafdc
 169 CFLAGS+=        -mabi=lp64
 170 CFLAGS.clang+=  -mcmodel=medium
 171 CFLAGS.gcc+=    -mcmodel=medany
 172 INLINE_LIMIT?=  8000
 173
 174 .if ${LINKER_FEATURES:Mriscv-relaxations} == ""
 175 CFLAGS+=        -mno-relax
 176 .endif
 177 .endif
 178
 179 #
 180 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 181 # operations inside the kernel itself.  These operations are exclusively
 182 # reserved for user applications.
 183 #
 184 # gcc:
 185 # Setting -mno-mmx implies -mno-3dnow
 186 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 187 #
 188 # clang:
 189 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 190 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 191 # (-mfpmath= is not supported)
 192 #
 193 .if ${MACHINE_CPUARCH} == "amd64"
 194 CFLAGS.clang+=  -mno-aes -mno-avx
 195 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 196                 -fno-asynchronous-unwind-tables
 197 INLINE_LIMIT?=  8000
 198 .endif
 199
 200 #
 201 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 202 # floating point registers for integer operations which it has a tendency to do.
 203 # Also explicitly disable Altivec instructions inside the kernel.
 204 #
 205 .if ${MACHINE_CPUARCH} == "powerpc"
 206 CFLAGS+=        -mno-altivec -msoft-float
 207 INLINE_LIMIT?=  15000
 208 .endif
 209
 210 .if ${MACHINE_ARCH} == "powerpcspe"
 211 CFLAGS.gcc+=    -mno-spe
 212 .endif
 213
 214 #
 215 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
 216 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 217 #
 218 .if ${MACHINE_ARCH:Mpowerpc64*} != "" && \
 219     ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 160000
 220 CFLAGS+=        -mabi=elfv2
 221 .endif
 222
 223 #
 224 # GCC 3.0 and above like to do certain optimizations based on the
 225 # assumption that the program is linked against libc.  Stop this.
 226 #
 227 CFLAGS+=        -ffreestanding
 228
 229 #
 230 # The C standard leaves signed integer overflow behavior undefined.
 231 # gcc and clang opimizers take advantage of this.  The kernel makes
 232 # use of signed integer wraparound mechanics so we need the compiler
 233 # to treat it as a wraparound and not take shortcuts.
 234 #
 235 CFLAGS+=        -fwrapv
 236
 237 #
 238 # GCC SSP support
 239 #
 240 .if ${MK_SSP} != "no"
 241 CFLAGS+=        -fstack-protector
 242 .endif
 243
 244 #
 245 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
 246 #
 247 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
 248     ${MK_KERNEL_RETPOLINE} != "no"
 249 CFLAGS+=        -mretpoline
 250 .endif
 251
 252 #
 253 # Initialize stack variables on function entry
 254 #
 255 .if ${MK_INIT_ALL_ZERO} == "yes"
 256 .if ${COMPILER_FEATURES:Minit-all}
 257 CFLAGS+= -ftrivial-auto-var-init=zero \
 258     -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
 259 .else
 260 .warning InitAll (zeros) requested but not support by compiler
 261 .endif
 262 .elif ${MK_INIT_ALL_PATTERN} == "yes"
 263 .if ${COMPILER_FEATURES:Minit-all}
 264 CFLAGS+= -ftrivial-auto-var-init=pattern
 265 .else
 266 .warning InitAll (pattern) requested but not support by compiler
 267 .endif
 268 .endif
 269
 270 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 271 CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}}
 272 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 273
 274 # Tell bmake not to mistake standard targets for things to be searched for
 275 # or expect to ever be up-to-date.
 276 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 277                 beforelinking build build-tools buildfiles buildincludes \
 278                 checkdpadd clean cleandepend cleandir cleanobj configure \
 279                 depend distclean distribute exe \
 280                 html includes install installfiles installincludes \
 281                 obj objlink objs objwarn \
 282                 realinstall regress \
 283                 tags whereobj
 284
 285 .PHONY: ${PHONY_NOTMAIN}
 286 .NOTMAIN: ${PHONY_NOTMAIN}
 287
 288 CSTD=           c99
 289
 290 .if ${CSTD} == "k&r"
 291 CFLAGS+=        -traditional
 292 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 293 CFLAGS+=        -std=iso9899:1990
 294 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 295 CFLAGS+=        -std=iso9899:199409
 296 .elif ${CSTD} == "c99"
 297 CFLAGS+=        -std=iso9899:1999
 298 .else # CSTD
 299 CFLAGS+=        -std=${CSTD}
 300 .endif # CSTD
 301
 302 # Please keep this if in sync with bsd.sys.mk
 303 .if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld")
 304 # Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld".
 305 .if ${COMPILER_TYPE} == "clang"
 306 # Note: Clang does not like relative paths for ld so we map ld.lld -> lld.
 307 .if ${COMPILER_VERSION} >= 120000
 308 CCLDFLAGS+=     --ld-path=${LD:[1]:S/^ld.//1W}
 309 .else
 310 CCLDFLAGS+=     -fuse-ld=${LD:[1]:S/^ld.//1W}
 311 .endif
 312 .else
 313 # GCC does not support an absolute path for -fuse-ld so we just print this
 314 # warning instead and let the user add the required symlinks.
 315 # However, we can avoid this warning if -B is set appropriately (e.g. for
 316 # CROSS_TOOLCHAIN=...-gcc).
 317 .if !(${LD:[1]:T} == "ld" && ${CC:tw:M-B${LD:[1]:H}/})
 318 .warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported
 319 .endif
 320 .endif
 321 .endif
 322
 323 # Set target-specific linker emulation name.
 324 LD_EMULATION_aarch64=aarch64elf
 325 LD_EMULATION_amd64=elf_x86_64_fbsd
 326 LD_EMULATION_arm=armelf_fbsd
 327 LD_EMULATION_armv6=armelf_fbsd
 328 LD_EMULATION_armv7=armelf_fbsd
 329 LD_EMULATION_i386=elf_i386_fbsd
 330 LD_EMULATION_powerpc= elf32ppc_fbsd
 331 LD_EMULATION_powerpcspe= elf32ppc_fbsd
 332 LD_EMULATION_powerpc64= elf64ppc_fbsd
 333 LD_EMULATION_powerpc64le= elf64lppc_fbsd
 334 LD_EMULATION_riscv64= elf64lriscv
 335 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}