sys/conf/kern.mk

   1 # $FreeBSD$
   2
   3 #
   4 # Warning flags for compiling the kernel and components of the kernel:
   5 #
   6 CWARNFLAGS?=    -Wall -Wredundant-decls -Wnested-externs -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 # Several other warnings which might be useful in some cases, but not severe
  29 # enough to error out the whole kernel build.  Display them anyway, so there is
  30 # some incentive to fix them eventually.
  31 CWARNEXTRA?=    -Wno-error-tautological-compare -Wno-error-empty-body \
  32                 -Wno-error-parentheses-equality -Wno-error-unused-function \
  33                 -Wno-error-pointer-sign
  34 CWARNEXTRA+=    -Wno-error-shift-negative-value
  35 CWARNEXTRA+=    -Wno-address-of-packed-member
  36 .if ${COMPILER_VERSION} >= 100000
  37 NO_WMISLEADING_INDENTATION=     -Wno-misleading-indentation
  38 .endif
  39 .endif  # clang
  40
  41 .if ${COMPILER_TYPE} == "gcc"
  42 # Catch-all for all the things that are in our tree, but for which we're
  43 # not yet ready for this compiler.
  44 NO_WUNUSED_BUT_SET_VARIABLE = -Wno-unused-but-set-variable
  45 CWARNEXTRA?=    -Wno-error=address                              \
  46                 -Wno-error=aggressive-loop-optimizations        \
  47                 -Wno-error=array-bounds                         \
  48                 -Wno-error=attributes                           \
  49                 -Wno-error=cast-qual                            \
  50                 -Wno-error=enum-compare                         \
  51                 -Wno-error=inline                               \
  52                 -Wno-error=maybe-uninitialized                  \
  53                 -Wno-error=misleading-indentation               \
  54                 -Wno-error=nonnull-compare                      \
  55                 -Wno-error=overflow                             \
  56                 -Wno-error=sequence-point                       \
  57                 -Wno-error=shift-overflow                       \
  58                 -Wno-error=tautological-compare                 \
  59                 -Wno-unused-but-set-variable
  60 .if ${COMPILER_VERSION} >= 70100
  61 CWARNEXTRA+=    -Wno-error=stringop-overflow
  62 .endif
  63 .if ${COMPILER_VERSION} >= 70200
  64 CWARNEXTRA+=    -Wno-error=memset-elt-size
  65 .endif
  66 .if ${COMPILER_VERSION} >= 80000
  67 CWARNEXTRA+=    -Wno-error=packed-not-aligned
  68 .endif
  69 .if ${COMPILER_VERSION} >= 90100
  70 CWARNEXTRA+=    -Wno-address-of-packed-member
  71 .endif
  72 .endif  # gcc
  73
  74 # This warning is utter nonsense
  75 CWARNFLAGS+=    -Wno-format-zero-length
  76
  77 # External compilers may not support our format extensions.  Allow them
  78 # to be disabled.  WARNING: format checking is disabled in this case.
  79 .if ${MK_FORMAT_EXTENSIONS} == "no"
  80 FORMAT_EXTENSIONS=      -Wno-format
  81 .elif ${COMPILER_TYPE} == "clang"
  82 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
  83 .else
  84 FORMAT_EXTENSIONS=      -fformat-extensions
  85 .endif
  86
  87 #
  88 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
  89 # and above adds code to the entry and exit point of every function to align the
  90 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
  91 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
  92 # it is probably an overall loss as it makes the code bigger (less efficient
  93 # use of code cache tag lines) and uses more stack (less efficient use of data
  94 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
  95 # operations inside the kernel itself.  These operations are exclusively
  96 # reserved for user applications.
  97 #
  98 # gcc:
  99 # Setting -mno-mmx implies -mno-3dnow
 100 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
 101 #
 102 # clang:
 103 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 104 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 105 #
 106 .if ${MACHINE_CPUARCH} == "i386"
 107 CFLAGS.gcc+=    -mno-align-long-strings -mpreferred-stack-boundary=2
 108 CFLAGS.clang+=  -mno-aes -mno-avx
 109 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 110 INLINE_LIMIT?=  8000
 111 .endif
 112
 113 .if ${MACHINE_CPUARCH} == "arm"
 114 INLINE_LIMIT?=  8000
 115 .endif
 116
 117 .if ${MACHINE_CPUARCH} == "aarch64"
 118 # We generally don't want fpu instructions in the kernel.
 119 CFLAGS += -mgeneral-regs-only
 120 # Reserve x18 for pcpu data
 121 CFLAGS += -ffixed-x18
 122 INLINE_LIMIT?=  8000
 123 .endif
 124
 125 #
 126 # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating
 127 # point registers within the kernel. However, for kernels supporting hardware
 128 # float (FPE), we have to include that in the march so we can have limited
 129 # floating point support in context switching needed for that. This is different
 130 # than userland where we use a hard-float ABI (lp64d).
 131 #
 132 # We also specify the "medium" code model, which generates code suitable for a
 133 # 2GiB addressing range located at any offset, allowing modules to be located
 134 # anywhere in the 64-bit address space.  Note that clang and GCC refer to this
 135 # code model as "medium" and "medany" respectively.
 136 #
 137 .if ${MACHINE_CPUARCH} == "riscv"
 138 CFLAGS+=        -march=rv64imafdc
 139 CFLAGS+=        -mabi=lp64
 140 CFLAGS.clang+=  -mcmodel=medium
 141 CFLAGS.gcc+=    -mcmodel=medany
 142 INLINE_LIMIT?=  8000
 143
 144 .if ${LINKER_FEATURES:Mriscv-relaxations} == ""
 145 CFLAGS+=        -mno-relax
 146 .endif
 147 .endif
 148
 149 #
 150 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 151 # operations inside the kernel itself.  These operations are exclusively
 152 # reserved for user applications.
 153 #
 154 # gcc:
 155 # Setting -mno-mmx implies -mno-3dnow
 156 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 157 #
 158 # clang:
 159 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 160 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 161 # (-mfpmath= is not supported)
 162 #
 163 .if ${MACHINE_CPUARCH} == "amd64"
 164 CFLAGS.clang+=  -mno-aes -mno-avx
 165 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 166                 -fno-asynchronous-unwind-tables
 167 INLINE_LIMIT?=  8000
 168 .endif
 169
 170 #
 171 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 172 # floating point registers for integer operations which it has a tendency to do.
 173 # Also explicitly disable Altivec instructions inside the kernel.
 174 #
 175 .if ${MACHINE_CPUARCH} == "powerpc"
 176 CFLAGS+=        -mno-altivec -msoft-float
 177 INLINE_LIMIT?=  15000
 178 .endif
 179
 180 .if ${MACHINE_ARCH} == "powerpcspe"
 181 CFLAGS.gcc+=    -mno-spe
 182 .endif
 183
 184 #
 185 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
 186 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 187 #
 188 .if ${MACHINE_ARCH:Mpowerpc64*} != ""
 189 CFLAGS+=        -mabi=elfv2
 190 .endif
 191
 192 #
 193 # For MIPS we also tell gcc to use floating point emulation
 194 #
 195 .if ${MACHINE_CPUARCH} == "mips"
 196 CFLAGS+=        -msoft-float
 197 INLINE_LIMIT?=  8000
 198 .endif
 199
 200 #
 201 # GCC 3.0 and above like to do certain optimizations based on the
 202 # assumption that the program is linked against libc.  Stop this.
 203 #
 204 CFLAGS+=        -ffreestanding
 205
 206 #
 207 # The C standard leaves signed integer overflow behavior undefined.
 208 # gcc and clang opimizers take advantage of this.  The kernel makes
 209 # use of signed integer wraparound mechanics so we need the compiler
 210 # to treat it as a wraparound and not take shortcuts.
 211 #
 212 CFLAGS+=        -fwrapv
 213
 214 #
 215 # GCC SSP support
 216 #
 217 .if ${MK_SSP} != "no" && \
 218     ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
 219 CFLAGS+=        -fstack-protector
 220 .endif
 221
 222 #
 223 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
 224 #
 225 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
 226     ${MK_KERNEL_RETPOLINE} != "no"
 227 CFLAGS+=        -mretpoline
 228 .endif
 229
 230 #
 231 # Initialize stack variables on function entry
 232 #
 233 .if ${MK_INIT_ALL_ZERO} == "yes"
 234 .if ${COMPILER_FEATURES:Minit-all}
 235 CFLAGS+= -ftrivial-auto-var-init=zero \
 236     -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
 237 .else
 238 .warning InitAll (zeros) requested but not support by compiler
 239 .endif
 240 .elif ${MK_INIT_ALL_PATTERN} == "yes"
 241 .if ${COMPILER_FEATURES:Minit-all}
 242 CFLAGS+= -ftrivial-auto-var-init=pattern
 243 .else
 244 .warning InitAll (pattern) requested but not support by compiler
 245 .endif
 246 .endif
 247
 248 #
 249 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
 250 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
 251 # cope well with DWARF 4, so force it to genereate DWARF2, which they
 252 # understand. Do this unconditionally as it is harmless when not needed,
 253 # but critical for these newer versions.
 254 #
 255 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
 256 CFLAGS+=        -gdwarf-2
 257 .endif
 258
 259 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 260 CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}}
 261 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 262
 263 # Tell bmake not to mistake standard targets for things to be searched for
 264 # or expect to ever be up-to-date.
 265 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 266                 beforelinking build build-tools buildfiles buildincludes \
 267                 checkdpadd clean cleandepend cleandir cleanobj configure \
 268                 depend distclean distribute exe \
 269                 html includes install installfiles installincludes \
 270                 obj objlink objs objwarn \
 271                 realinstall regress \
 272                 tags whereobj
 273
 274 .PHONY: ${PHONY_NOTMAIN}
 275 .NOTMAIN: ${PHONY_NOTMAIN}
 276
 277 CSTD=           c99
 278
 279 .if ${CSTD} == "k&r"
 280 CFLAGS+=        -traditional
 281 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 282 CFLAGS+=        -std=iso9899:1990
 283 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 284 CFLAGS+=        -std=iso9899:199409
 285 .elif ${CSTD} == "c99"
 286 CFLAGS+=        -std=iso9899:1999
 287 .else # CSTD
 288 CFLAGS+=        -std=${CSTD}
 289 .endif # CSTD
 290
 291 # Please keep this if in sync with bsd.sys.mk
 292 .if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld")
 293 # Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld".
 294 # Note: Clang 12+ will prefer --ld-path= over -fuse-ld=.
 295 .if ${COMPILER_TYPE} == "clang"
 296 # Note: unlike bsd.sys.mk we can't use LDFLAGS here since that is used for the
 297 # flags required when linking the kernel. We don't need those flags when
 298 # building the vdsos. However, we do need -fuse-ld, so use ${CCLDFLAGS} instead.
 299 # Note: Clang does not like relative paths in -fuse-ld so we map ld.lld -> lld.
 300 CCLDFLAGS+=     -fuse-ld=${LD:[1]:S/^ld.//1W}
 301 .else
 302 # GCC does not support an absolute path for -fuse-ld so we just print this
 303 # warning instead and let the user add the required symlinks.
 304 .warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported
 305 .endif
 306 .endif
 307
 308 # Set target-specific linker emulation name.
 309 LD_EMULATION_aarch64=aarch64elf
 310 LD_EMULATION_amd64=elf_x86_64_fbsd
 311 LD_EMULATION_arm=armelf_fbsd
 312 LD_EMULATION_armv6=armelf_fbsd
 313 LD_EMULATION_armv7=armelf_fbsd
 314 LD_EMULATION_i386=elf_i386_fbsd
 315 LD_EMULATION_mips= elf32btsmip_fbsd
 316 LD_EMULATION_mipshf= elf32btsmip_fbsd
 317 LD_EMULATION_mips64= elf64btsmip_fbsd
 318 LD_EMULATION_mips64hf= elf64btsmip_fbsd
 319 LD_EMULATION_mipsel= elf32ltsmip_fbsd
 320 LD_EMULATION_mipselhf= elf32ltsmip_fbsd
 321 LD_EMULATION_mips64el= elf64ltsmip_fbsd
 322 LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
 323 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
 324 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd   # I don't think this is a thing that works
 325 LD_EMULATION_powerpc= elf32ppc_fbsd
 326 LD_EMULATION_powerpcspe= elf32ppc_fbsd
 327 LD_EMULATION_powerpc64= elf64ppc_fbsd
 328 LD_EMULATION_powerpc64le= elf64lppc_fbsd
 329 LD_EMULATION_riscv64= elf64lriscv
 330 LD_EMULATION_riscv64sf= elf64lriscv
 331 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}