sys/conf/kern.mk

   1
   2 #
   3 # Warning flags for compiling the kernel and components of the kernel:
   4 #
   5 CWARNFLAGS?=    -Wall -Wstrict-prototypes \
   6                 -Wmissing-prototypes -Wpointer-arith -Wcast-qual \
   7                 -Wundef -Wno-pointer-sign ${FORMAT_EXTENSIONS} \
   8                 -Wmissing-include-dirs -fdiagnostics-show-option \
   9                 -Wno-unknown-pragmas \
  10                 ${CWARNEXTRA}
  11 #
  12 # The following flags are next up for working on:
  13 #       -Wextra
  14
  15 # Disable a few warnings for clang, since there are several places in the
  16 # kernel where fixing them is more trouble than it is worth, or where there is
  17 # a false positive.
  18 .if ${COMPILER_TYPE} == "clang"
  19 NO_WCONSTANT_CONVERSION=        -Wno-error=constant-conversion
  20 NO_WSHIFT_COUNT_NEGATIVE=       -Wno-shift-count-negative
  21 NO_WSHIFT_COUNT_OVERFLOW=       -Wno-shift-count-overflow
  22 NO_WSELF_ASSIGN=                -Wno-self-assign
  23 NO_WUNNEEDED_INTERNAL_DECL=     -Wno-error=unneeded-internal-declaration
  24 NO_WSOMETIMES_UNINITIALIZED=    -Wno-error=sometimes-uninitialized
  25 NO_WCAST_QUAL=                  -Wno-error=cast-qual
  26 NO_WTAUTOLOGICAL_POINTER_COMPARE= -Wno-tautological-pointer-compare
  27 .if ${COMPILER_VERSION} >= 100000
  28 NO_WMISLEADING_INDENTATION=     -Wno-misleading-indentation
  29 .endif
  30 .if ${COMPILER_VERSION} >= 130000
  31 NO_WUNUSED_BUT_SET_VARIABLE=    -Wno-unused-but-set-variable
  32 .endif
  33 .if ${COMPILER_VERSION} >= 140000
  34 NO_WBITWISE_INSTEAD_OF_LOGICAL= -Wno-bitwise-instead-of-logical
  35 .endif
  36 .if ${COMPILER_VERSION} >= 150000
  37 NO_WSTRICT_PROTOTYPES=          -Wno-strict-prototypes
  38 NO_WDEPRECATED_NON_PROTOTYPE=   -Wno-deprecated-non-prototype
  39 .endif
  40 # Several other warnings which might be useful in some cases, but not severe
  41 # enough to error out the whole kernel build.  Display them anyway, so there is
  42 # some incentive to fix them eventually.
  43 CWARNEXTRA?=    -Wno-error=tautological-compare -Wno-error=empty-body \
  44                 -Wno-error=parentheses-equality -Wno-error=unused-function \
  45                 -Wno-error=pointer-sign
  46 CWARNEXTRA+=    -Wno-error=shift-negative-value
  47 CWARNEXTRA+=    -Wno-address-of-packed-member
  48 .endif  # clang
  49
  50 .if ${COMPILER_TYPE} == "gcc"
  51 # Catch-all for all the things that are in our tree, but for which we're
  52 # not yet ready for this compiler.
  53 NO_WUNUSED_BUT_SET_VARIABLE=-Wno-unused-but-set-variable
  54 CWARNEXTRA?=    -Wno-error=address                              \
  55                 -Wno-error=aggressive-loop-optimizations        \
  56                 -Wno-error=array-bounds                         \
  57                 -Wno-error=attributes                           \
  58                 -Wno-error=cast-qual                            \
  59                 -Wno-error=enum-compare                         \
  60                 -Wno-error=maybe-uninitialized                  \
  61                 -Wno-error=misleading-indentation               \
  62                 -Wno-error=nonnull-compare                      \
  63                 -Wno-error=overflow                             \
  64                 -Wno-error=sequence-point                       \
  65                 -Wno-error=shift-overflow                       \
  66                 -Wno-error=tautological-compare                 \
  67                 -Wno-error=unused-function
  68 .if ${COMPILER_VERSION} >= 70100
  69 CWARNEXTRA+=    -Wno-error=stringop-overflow
  70 .endif
  71 .if ${COMPILER_VERSION} >= 70200
  72 CWARNEXTRA+=    -Wno-error=memset-elt-size
  73 .endif
  74 .if ${COMPILER_VERSION} >= 80000
  75 CWARNEXTRA+=    -Wno-error=packed-not-aligned
  76 .endif
  77 .if ${COMPILER_VERSION} >= 90100
  78 CWARNEXTRA+=    -Wno-address-of-packed-member                   \
  79                 -Wno-error=alloca-larger-than=
  80 .if ${COMPILER_VERSION} >= 120100
  81 CWARNEXTRA+=    -Wno-error=nonnull                              \
  82                 -Wno-dangling-pointer                           \
  83                 -Wno-zero-length-bounds
  84 NO_WINFINITE_RECURSION= -Wno-infinite-recursion
  85 NO_WSTRINGOP_OVERREAD=  -Wno-stringop-overread
  86 .endif
  87 .endif
  88
  89 # GCC produces false positives for functions that switch on an
  90 # enum (GCC bug 87950)
  91 CWARNFLAGS+=    -Wno-return-type
  92 .endif  # gcc
  93
  94 # This warning is utter nonsense
  95 CWARNFLAGS+=    -Wno-format-zero-length
  96
  97 # External compilers may not support our format extensions.  Allow them
  98 # to be disabled.  WARNING: format checking is disabled in this case.
  99 .if ${MK_FORMAT_EXTENSIONS} == "no"
 100 FORMAT_EXTENSIONS=      -Wno-format
 101 .elif ${COMPILER_TYPE} == "clang" || \
 102     (${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 120100)
 103 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
 104 .else
 105 FORMAT_EXTENSIONS=      -fformat-extensions
 106 .endif
 107
 108 #
 109 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
 110 # and above adds code to the entry and exit point of every function to align the
 111 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
 112 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
 113 # it is probably an overall loss as it makes the code bigger (less efficient
 114 # use of code cache tag lines) and uses more stack (less efficient use of data
 115 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
 116 # operations inside the kernel itself.  These operations are exclusively
 117 # reserved for user applications.
 118 #
 119 # gcc:
 120 # Setting -mno-mmx implies -mno-3dnow
 121 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
 122 #
 123 # clang:
 124 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 125 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 126 #
 127 .if ${MACHINE_CPUARCH} == "i386"
 128 CFLAGS.gcc+=    -mpreferred-stack-boundary=2
 129 CFLAGS.clang+=  -mno-aes -mno-avx
 130 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 131 INLINE_LIMIT?=  8000
 132 .endif
 133
 134 .if ${MACHINE_CPUARCH} == "arm"
 135 INLINE_LIMIT?=  8000
 136 .endif
 137
 138 .if ${MACHINE_CPUARCH} == "aarch64"
 139 # We generally don't want fpu instructions in the kernel.
 140 CFLAGS += -mgeneral-regs-only
 141 # Reserve x18 for pcpu data
 142 CFLAGS += -ffixed-x18
 143 INLINE_LIMIT?=  8000
 144 .endif
 145
 146 #
 147 # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating
 148 # point registers within the kernel. However, we include the F and D extensions
 149 # in -march so we can have limited floating point support in context switching
 150 # code. This is different than userland where we use a hard-float ABI (lp64d).
 151 #
 152 # We also specify the "medium" code model, which generates code suitable for a
 153 # 2GiB addressing range located at any offset, allowing modules to be located
 154 # anywhere in the 64-bit address space.  Note that clang and GCC refer to this
 155 # code model as "medium" and "medany" respectively.
 156 #
 157 .if ${MACHINE_CPUARCH} == "riscv"
 158 CFLAGS+=        -march=rv64imafdc
 159 CFLAGS+=        -mabi=lp64
 160 CFLAGS.clang+=  -mcmodel=medium
 161 CFLAGS.gcc+=    -mcmodel=medany
 162 INLINE_LIMIT?=  8000
 163
 164 .if ${LINKER_FEATURES:Mriscv-relaxations} == ""
 165 CFLAGS+=        -mno-relax
 166 .endif
 167 .endif
 168
 169 #
 170 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 171 # operations inside the kernel itself.  These operations are exclusively
 172 # reserved for user applications.
 173 #
 174 # gcc:
 175 # Setting -mno-mmx implies -mno-3dnow
 176 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 177 #
 178 # clang:
 179 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 180 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 181 # (-mfpmath= is not supported)
 182 #
 183 .if ${MACHINE_CPUARCH} == "amd64"
 184 CFLAGS.clang+=  -mno-aes -mno-avx
 185 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 186                 -fno-asynchronous-unwind-tables
 187 INLINE_LIMIT?=  8000
 188 .endif
 189
 190 #
 191 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 192 # floating point registers for integer operations which it has a tendency to do.
 193 # Also explicitly disable Altivec instructions inside the kernel.
 194 #
 195 .if ${MACHINE_CPUARCH} == "powerpc"
 196 CFLAGS+=        -mno-altivec -msoft-float
 197 INLINE_LIMIT?=  15000
 198 .endif
 199
 200 .if ${MACHINE_ARCH} == "powerpcspe"
 201 CFLAGS.gcc+=    -mno-spe
 202 .endif
 203
 204 #
 205 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
 206 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 207 #
 208 .if ${MACHINE_ARCH:Mpowerpc64*} != "" && \
 209     ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 160000
 210 CFLAGS+=        -mabi=elfv2
 211 .endif
 212
 213 #
 214 # GCC 3.0 and above like to do certain optimizations based on the
 215 # assumption that the program is linked against libc.  Stop this.
 216 #
 217 CFLAGS+=        -ffreestanding
 218
 219 #
 220 # The C standard leaves signed integer overflow behavior undefined.
 221 # gcc and clang opimizers take advantage of this.  The kernel makes
 222 # use of signed integer wraparound mechanics so we need the compiler
 223 # to treat it as a wraparound and not take shortcuts.
 224 #
 225 CFLAGS+=        -fwrapv
 226
 227 #
 228 # GCC SSP support
 229 #
 230 .if ${MK_SSP} != "no"
 231 CFLAGS+=        -fstack-protector
 232 .endif
 233
 234 #
 235 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
 236 #
 237 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
 238     ${MK_KERNEL_RETPOLINE} != "no"
 239 CFLAGS+=        -mretpoline
 240 .endif
 241
 242 #
 243 # Initialize stack variables on function entry
 244 #
 245 .if ${OPT_INIT_ALL} != "none"
 246 .if ${COMPILER_FEATURES:Minit-all}
 247 CFLAGS+= -ftrivial-auto-var-init=${OPT_INIT_ALL}
 248 .if ${OPT_INIT_ALL} == "zero" && ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 160000
 249 CFLAGS+= -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
 250 .endif
 251 .else
 252 .warning INIT_ALL (${OPT_INIT_ALL}) requested but not supported by compiler
 253 .endif
 254 .endif
 255
 256 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 257 CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}}
 258 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 259
 260 # Tell bmake not to mistake standard targets for things to be searched for
 261 # or expect to ever be up-to-date.
 262 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 263                 beforelinking build build-tools buildfiles buildincludes \
 264                 checkdpadd clean cleandepend cleandir cleanobj configure \
 265                 depend distclean distribute exe \
 266                 html includes install installfiles installincludes \
 267                 obj objlink objs objwarn \
 268                 realinstall regress \
 269                 tags whereobj
 270
 271 .PHONY: ${PHONY_NOTMAIN}
 272 .NOTMAIN: ${PHONY_NOTMAIN}
 273
 274 CSTD?=          gnu99
 275
 276 .if ${CSTD} == "k&r"
 277 CFLAGS+=        -traditional
 278 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 279 CFLAGS+=        -std=iso9899:1990
 280 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 281 CFLAGS+=        -std=iso9899:199409
 282 .elif ${CSTD} == "c99"
 283 CFLAGS+=        -std=iso9899:1999
 284 .else # CSTD
 285 CFLAGS+=        -std=${CSTD}
 286 .endif # CSTD
 287
 288 # Please keep this if in sync with bsd.sys.mk
 289 .if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld")
 290 # Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld".
 291 .if ${COMPILER_TYPE} == "clang"
 292 # Note: Clang does not like relative paths for ld so we map ld.lld -> lld.
 293 .if ${COMPILER_VERSION} >= 120000
 294 CCLDFLAGS+=     --ld-path=${LD:[1]:S/^ld.//1W}
 295 .else
 296 CCLDFLAGS+=     -fuse-ld=${LD:[1]:S/^ld.//1W}
 297 .endif
 298 .else
 299 # GCC does not support an absolute path for -fuse-ld so we just print this
 300 # warning instead and let the user add the required symlinks.
 301 # However, we can avoid this warning if -B is set appropriately (e.g. for
 302 # CROSS_TOOLCHAIN=...-gcc).
 303 .if !(${LD:[1]:T} == "ld" && ${CC:tw:M-B${LD:[1]:H}/})
 304 .warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported
 305 .endif
 306 .endif
 307 .endif
 308
 309 # Set target-specific linker emulation name.
 310 LD_EMULATION_aarch64=aarch64elf
 311 LD_EMULATION_amd64=elf_x86_64_fbsd
 312 LD_EMULATION_arm=armelf_fbsd
 313 LD_EMULATION_armv6=armelf_fbsd
 314 LD_EMULATION_armv7=armelf_fbsd
 315 LD_EMULATION_i386=elf_i386_fbsd
 316 LD_EMULATION_powerpc= elf32ppc_fbsd
 317 LD_EMULATION_powerpcspe= elf32ppc_fbsd
 318 LD_EMULATION_powerpc64= elf64ppc_fbsd
 319 LD_EMULATION_powerpc64le= elf64lppc_fbsd
 320 LD_EMULATION_riscv64= elf64lriscv
 321 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}