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 -Wswitch \
  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-alloc-size-larger-than                     \
  80                 -Wno-error=alloca-larger-than=
  81 .if ${COMPILER_VERSION} >= 120100
  82 CWARNEXTRA+=    -Wno-error=nonnull                              \
  83                 -Wno-dangling-pointer                           \
  84                 -Wno-zero-length-bounds
  85 NO_WINFINITE_RECURSION= -Wno-infinite-recursion
  86 NO_WSTRINGOP_OVERREAD=  -Wno-stringop-overread
  87 .endif
  88 .endif
  89
  90 # GCC produces false positives for functions that switch on an
  91 # enum (GCC bug 87950)
  92 CWARNFLAGS+=    -Wno-return-type
  93 .endif  # gcc
  94
  95 # This warning is utter nonsense
  96 CWARNFLAGS+=    -Wno-format-zero-length
  97
  98 # External compilers may not support our format extensions.  Allow them
  99 # to be disabled.  WARNING: format checking is disabled in this case.
 100 .if ${MK_FORMAT_EXTENSIONS} == "no"
 101 FORMAT_EXTENSIONS=      -Wno-format
 102 .elif ${COMPILER_TYPE} == "clang" || \
 103     (${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 120100)
 104 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
 105 .else
 106 FORMAT_EXTENSIONS=      -fformat-extensions
 107 .endif
 108
 109 #
 110 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
 111 # and above adds code to the entry and exit point of every function to align the
 112 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
 113 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
 114 # it is probably an overall loss as it makes the code bigger (less efficient
 115 # use of code cache tag lines) and uses more stack (less efficient use of data
 116 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
 117 # operations inside the kernel itself.  These operations are exclusively
 118 # reserved for user applications.
 119 #
 120 # gcc:
 121 # Setting -mno-mmx implies -mno-3dnow
 122 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
 123 #
 124 # clang:
 125 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 126 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 127 #
 128 .if ${MACHINE_CPUARCH} == "i386"
 129 CFLAGS.gcc+=    -mpreferred-stack-boundary=2
 130 CFLAGS.clang+=  -mno-aes -mno-avx
 131 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 132 INLINE_LIMIT?=  8000
 133 .endif
 134
 135 .if ${MACHINE_CPUARCH} == "arm"
 136 INLINE_LIMIT?=  8000
 137 .endif
 138
 139 .if ${MACHINE_CPUARCH} == "aarch64"
 140 # We generally don't want fpu instructions in the kernel.
 141 CFLAGS += -mgeneral-regs-only
 142 # Reserve x18 for pcpu data
 143 CFLAGS += -ffixed-x18
 144 # Build with BTI+PAC
 145 CFLAGS += -mbranch-protection=standard
 146 INLINE_LIMIT?=  8000
 147 .endif
 148
 149 #
 150 # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating
 151 # point registers within the kernel. However, we include the F and D extensions
 152 # in -march so we can have limited floating point support in context switching
 153 # code. This is different than userland where we use a hard-float ABI (lp64d).
 154 #
 155 # We also specify the "medium" code model, which generates code suitable for a
 156 # 2GiB addressing range located at any offset, allowing modules to be located
 157 # anywhere in the 64-bit address space.  Note that clang and GCC refer to this
 158 # code model as "medium" and "medany" respectively.
 159 #
 160 .if ${MACHINE_CPUARCH} == "riscv"
 161 CFLAGS+=        -march=rv64imafdc
 162 CFLAGS+=        -mabi=lp64
 163 CFLAGS.clang+=  -mcmodel=medium
 164 CFLAGS.gcc+=    -mcmodel=medany
 165 INLINE_LIMIT?=  8000
 166
 167 .if ${LINKER_FEATURES:Mriscv-relaxations} == ""
 168 CFLAGS+=        -mno-relax
 169 .endif
 170 .endif
 171
 172 #
 173 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 174 # operations inside the kernel itself.  These operations are exclusively
 175 # reserved for user applications.
 176 #
 177 # gcc:
 178 # Setting -mno-mmx implies -mno-3dnow
 179 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 180 #
 181 # clang:
 182 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 183 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 184 # (-mfpmath= is not supported)
 185 #
 186 .if ${MACHINE_CPUARCH} == "amd64"
 187 CFLAGS.clang+=  -mno-aes -mno-avx
 188 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 189                 -fno-asynchronous-unwind-tables
 190 INLINE_LIMIT?=  8000
 191 .endif
 192
 193 #
 194 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 195 # floating point registers for integer operations which it has a tendency to do.
 196 # Also explicitly disable Altivec instructions inside the kernel.
 197 #
 198 .if ${MACHINE_CPUARCH} == "powerpc"
 199 CFLAGS+=        -mno-altivec -msoft-float
 200 INLINE_LIMIT?=  15000
 201 .endif
 202
 203 .if ${MACHINE_ARCH} == "powerpcspe"
 204 CFLAGS.gcc+=    -mno-spe
 205 .endif
 206
 207 #
 208 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
 209 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 210 #
 211 .if ${MACHINE_ARCH:Mpowerpc64*} != "" && \
 212     ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 160000
 213 CFLAGS+=        -mabi=elfv2
 214 .endif
 215
 216 #
 217 # GCC 3.0 and above like to do certain optimizations based on the
 218 # assumption that the program is linked against libc.  Stop this.
 219 #
 220 CFLAGS+=        -ffreestanding
 221
 222 #
 223 # The C standard leaves signed integer overflow behavior undefined.
 224 # gcc and clang opimizers take advantage of this.  The kernel makes
 225 # use of signed integer wraparound mechanics so we need the compiler
 226 # to treat it as a wraparound and not take shortcuts.
 227 #
 228 CFLAGS+=        -fwrapv
 229
 230 #
 231 # GCC SSP support
 232 #
 233 .if ${MK_SSP} != "no"
 234 CFLAGS+=        -fstack-protector
 235 .endif
 236
 237 #
 238 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
 239 #
 240 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
 241     ${MK_KERNEL_RETPOLINE} != "no"
 242 CFLAGS+=        -mretpoline
 243 .endif
 244
 245 #
 246 # Initialize stack variables on function entry
 247 #
 248 .if ${OPT_INIT_ALL} != "none"
 249 .if ${COMPILER_FEATURES:Minit-all}
 250 CFLAGS+= -ftrivial-auto-var-init=${OPT_INIT_ALL}
 251 .if ${OPT_INIT_ALL} == "zero" && ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 160000
 252 CFLAGS+= -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
 253 .endif
 254 .else
 255 .warning INIT_ALL (${OPT_INIT_ALL}) requested but not supported by compiler
 256 .endif
 257 .endif
 258
 259 #
 260 # Some newer toolchains default to DWARF 5, which isn't supported by some build
 261 # tools yet.
 262 #
 263 .if (${CFLAGS:M-g} != "" || ${CFLAGS:M-g[0-3]} != "") && ${CFLAGS:M-gdwarf*} == ""
 264 CFLAGS+=        -gdwarf-4
 265 .endif
 266
 267 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 268 CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}}
 269 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 270
 271 # Tell bmake not to mistake standard targets for things to be searched for
 272 # or expect to ever be up-to-date.
 273 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 274                 beforelinking build build-tools buildfiles buildincludes \
 275                 checkdpadd clean cleandepend cleandir cleanobj configure \
 276                 depend distclean distribute exe \
 277                 html includes install installfiles installincludes \
 278                 obj objlink objs objwarn \
 279                 realinstall regress \
 280                 tags whereobj
 281
 282 .PHONY: ${PHONY_NOTMAIN}
 283 .NOTMAIN: ${PHONY_NOTMAIN}
 284
 285 CSTD?=          gnu99
 286
 287 .if ${CSTD} == "k&r"
 288 CFLAGS+=        -traditional
 289 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 290 CFLAGS+=        -std=iso9899:1990
 291 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 292 CFLAGS+=        -std=iso9899:199409
 293 .elif ${CSTD} == "c99"
 294 CFLAGS+=        -std=iso9899:1999
 295 .else # CSTD
 296 CFLAGS+=        -std=${CSTD}
 297 .endif # CSTD
 298
 299 # Please keep this if in sync with bsd.sys.mk
 300 .if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld")
 301 # Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld".
 302 .if ${COMPILER_TYPE} == "clang"
 303 # Note: Clang does not like relative paths for ld so we map ld.lld -> lld.
 304 .if ${COMPILER_VERSION} >= 120000
 305 CCLDFLAGS+=     --ld-path=${LD:[1]:S/^ld.//1W}
 306 .else
 307 CCLDFLAGS+=     -fuse-ld=${LD:[1]:S/^ld.//1W}
 308 .endif
 309 .else
 310 # GCC does not support an absolute path for -fuse-ld so we just print this
 311 # warning instead and let the user add the required symlinks.
 312 # However, we can avoid this warning if -B is set appropriately (e.g. for
 313 # CROSS_TOOLCHAIN=...-gcc).
 314 .if !(${LD:[1]:T} == "ld" && ${CC:tw:M-B${LD:[1]:H}/})
 315 .warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported
 316 .endif
 317 .endif
 318 .endif
 319
 320 # Set target-specific linker emulation name.
 321 LD_EMULATION_aarch64=aarch64elf
 322 LD_EMULATION_amd64=elf_x86_64_fbsd
 323 LD_EMULATION_arm=armelf_fbsd
 324 LD_EMULATION_armv6=armelf_fbsd
 325 LD_EMULATION_armv7=armelf_fbsd
 326 LD_EMULATION_i386=elf_i386_fbsd
 327 LD_EMULATION_powerpc= elf32ppc_fbsd
 328 LD_EMULATION_powerpcspe= elf32ppc_fbsd
 329 LD_EMULATION_powerpc64= elf64ppc_fbsd
 330 LD_EMULATION_powerpc64le= elf64lppc_fbsd
 331 LD_EMULATION_riscv64= elf64lriscv
 332 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}