scripts/Makefile.build

   1 # SPDX-License-Identifier: GPL-2.0
   2 # ==========================================================================
   3 # Building
   4 # ==========================================================================
   5
   6 src := $(obj)
   7
   8 PHONY := __build
   9 __build:
  10
  11 # Init all relevant variables used in kbuild files so
  12 # 1) they have correct type
  13 # 2) they do not inherit any value from the environment
  14 obj-y :=
  15 obj-m :=
  16 lib-y :=
  17 lib-m :=
  18 always-y :=
  19 always-m :=
  20 targets :=
  21 subdir-y :=
  22 subdir-m :=
  23 EXTRA_AFLAGS   :=
  24 EXTRA_CFLAGS   :=
  25 EXTRA_CPPFLAGS :=
  26 EXTRA_LDFLAGS  :=
  27 asflags-y  :=
  28 ccflags-y  :=
  29 cppflags-y :=
  30 ldflags-y  :=
  31
  32 subdir-asflags-y :=
  33 subdir-ccflags-y :=
  34
  35 # Read auto.conf if it exists, otherwise ignore
  36 -include include/config/auto.conf
  37
  38 include $(srctree)/scripts/Kbuild.include
  39 include $(srctree)/scripts/Makefile.compiler
  40
  41 # The filename Kbuild has precedence over Makefile
  42 kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
  43 kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
  44 include $(kbuild-file)
  45
  46 include $(srctree)/scripts/Makefile.lib
  47
  48 # Do not include hostprogs rules unless needed.
  49 # $(sort ...) is used here to remove duplicated words and excessive spaces.
  50 hostprogs := $(sort $(hostprogs))
  51 ifneq ($(hostprogs),)
  52 include $(srctree)/scripts/Makefile.host
  53 endif
  54
  55 # Do not include userprogs rules unless needed.
  56 # $(sort ...) is used here to remove duplicated words and excessive spaces.
  57 userprogs := $(sort $(userprogs))
  58 ifneq ($(userprogs),)
  59 include $(srctree)/scripts/Makefile.userprogs
  60 endif
  61
  62 ifndef obj
  63 $(warning kbuild: Makefile.build is included improperly)
  64 endif
  65
  66 ifeq ($(need-modorder),)
  67 ifneq ($(obj-m),)
  68 $(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
  69 $(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)
  70 endif
  71 endif
  72
  73 # ===========================================================================
  74
  75 # subdir-builtin and subdir-modorder may contain duplications. Use $(sort ...)
  76 subdir-builtin := $(sort $(filter %/built-in.a, $(real-obj-y)))
  77 subdir-modorder := $(sort $(filter %/modules.order, $(obj-m)))
  78
  79 targets-for-builtin := $(extra-y)
  80
  81 ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
  82 targets-for-builtin += $(obj)/lib.a
  83 endif
  84
  85 ifdef need-builtin
  86 targets-for-builtin += $(obj)/built-in.a
  87 endif
  88
  89 targets-for-modules := $(patsubst %.o, %.mod, $(filter %.o, $(obj-m)))
  90
  91 ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
  92 targets-for-modules += $(patsubst %.o, %.prelink.o, $(filter %.o, $(obj-m)))
  93 endif
  94
  95 ifdef need-modorder
  96 targets-for-modules += $(obj)/modules.order
  97 endif
  98
  99 targets += $(targets-for-builtin) $(targets-for-modules)
 100
 101 # Linus' kernel sanity checking tool
 102 ifeq ($(KBUILD_CHECKSRC),1)
 103   quiet_cmd_checksrc       = CHECK   $<
 104         cmd_checksrc       = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
 105 else ifeq ($(KBUILD_CHECKSRC),2)
 106   quiet_cmd_force_checksrc = CHECK   $<
 107         cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
 108 endif
 109
 110 ifneq ($(KBUILD_EXTRA_WARN),)
 111   cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $<
 112 endif
 113
 114 # Compile C sources (.c)
 115 # ---------------------------------------------------------------------------
 116
 117 quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
 118       cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) -fverbose-asm -S -o $@ $<
 119
 120 $(obj)/%.s: $(src)/%.c FORCE
 121         $(call if_changed_dep,cc_s_c)
 122
 123 quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
 124 cmd_cpp_i_c       = $(CPP) $(c_flags) -o $@ $<
 125
 126 $(obj)/%.i: $(src)/%.c FORCE
 127         $(call if_changed_dep,cpp_i_c)
 128
 129 # These mirror gensymtypes_S and co below, keep them in synch.
 130 cmd_gensymtypes_c =                                                         \
 131     $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
 132     scripts/genksyms/genksyms $(if $(1), -T $(2))                           \
 133      $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
 134      $(if $(KBUILD_PRESERVE),-p)                                            \
 135      -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
 136
 137 quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
 138 cmd_cc_symtypes_c =                                                         \
 139     $(call cmd_gensymtypes_c,true,$@) >/dev/null;                           \
 140     test -s $@ || rm -f $@
 141
 142 $(obj)/%.symtypes : $(src)/%.c FORCE
 143         $(call cmd,cc_symtypes_c)
 144
 145 # LLVM assembly
 146 # Generate .ll files from .c
 147 quiet_cmd_cc_ll_c = CC $(quiet_modtag)  $@
 148       cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
 149
 150 $(obj)/%.ll: $(src)/%.c FORCE
 151         $(call if_changed_dep,cc_ll_c)
 152
 153 # C (.c) files
 154 # The C file is compiled and updated dependency information is generated.
 155 # (See cmd_cc_o_c + relevant part of rule_cc_o_c)
 156
 157 quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@
 158       cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< $(cmd_objtool)
 159
 160 ifdef CONFIG_MODVERSIONS
 161 # When module versioning is enabled the following steps are executed:
 162 # o compile a <file>.o from <file>.c
 163 # o if <file>.o doesn't contain a __ksymtab version, i.e. does
 164 #   not export symbols, it's done.
 165 # o otherwise, we calculate symbol versions using the good old
 166 #   genksyms on the preprocessed source and postprocess them in a way
 167 #   that they are usable as a linker script
 168 # o generate .tmp_<file>.o from <file>.o using the linker to
 169 #   replace the unresolved symbols __crc_exported_symbol with
 170 #   the actual value of the checksum generated by genksyms
 171 # o remove .tmp_<file>.o to <file>.o
 172
 173 ifdef CONFIG_LTO_CLANG
 174 # Generate .o.symversions files for each .o with exported symbols, and link these
 175 # to the kernel and/or modules at the end.
 176 cmd_modversions_c =                                                             \
 177         if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then                       \
 178                 $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))  \
 179                     > $@.symversions;                                           \
 180         else                                                                    \
 181                 rm -f $@.symversions;                                           \
 182         fi;
 183 else
 184 cmd_modversions_c =                                                             \
 185         if $(OBJDUMP) -h $@ | grep -q __ksymtab; then                           \
 186                 $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))  \
 187                     > $(@D)/.tmp_$(@F:.o=.ver);                                 \
 188                                                                                 \
 189                 $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@               \
 190                         -T $(@D)/.tmp_$(@F:.o=.ver);                            \
 191                 mv -f $(@D)/.tmp_$(@F) $@;                                      \
 192                 rm -f $(@D)/.tmp_$(@F:.o=.ver);                                 \
 193         fi
 194 endif
 195 endif
 196
 197 ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
 198 # compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
 199 ifdef BUILD_C_RECORDMCOUNT
 200 ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
 201   RECORDMCOUNT_FLAGS = -w
 202 endif
 203 # Due to recursion, we must skip empty.o.
 204 # The empty.o file is created in the make process in order to determine
 205 # the target endianness and word size. It is made before all other C
 206 # files, including recordmcount.
 207 sub_cmd_record_mcount =                                 \
 208         if [ $(@) != "scripts/mod/empty.o" ]; then      \
 209                 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";   \
 210         fi;
 211 recordmcount_source := $(srctree)/scripts/recordmcount.c \
 212                     $(srctree)/scripts/recordmcount.h
 213 else
 214 sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
 215         "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
 216         "$(if $(CONFIG_64BIT),64,32)" \
 217         "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
 218         "$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
 219         "$(if $(part-of-module),1,0)" "$(@)";
 220 recordmcount_source := $(srctree)/scripts/recordmcount.pl
 221 endif # BUILD_C_RECORDMCOUNT
 222 cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
 223         $(sub_cmd_record_mcount))
 224 endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
 225
 226 ifdef CONFIG_STACK_VALIDATION
 227
 228 objtool := $(objtree)/tools/objtool/objtool
 229
 230 objtool_args =                                                          \
 231         $(if $(CONFIG_UNWINDER_ORC),orc generate,check)                 \
 232         $(if $(part-of-module), --module)                               \
 233         $(if $(CONFIG_X86_KERNEL_IBT), --lto --ibt)                     \
 234         $(if $(CONFIG_FRAME_POINTER),, --no-fp)                         \
 235         $(if $(CONFIG_GCOV_KERNEL)$(CONFIG_LTO_CLANG), --no-unreachable)\
 236         $(if $(CONFIG_RETPOLINE), --retpoline)                          \
 237         $(if $(CONFIG_X86_SMAP), --uaccess)                             \
 238         $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount)             \
 239         $(if $(CONFIG_SLS), --sls)
 240
 241 cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
 242 cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
 243
 244 endif # CONFIG_STACK_VALIDATION
 245
 246 ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
 247
 248 # Skip objtool for LLVM bitcode
 249 $(obj)/%.o: objtool-enabled :=
 250
 251 else
 252
 253 # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
 254 # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
 255 # 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
 256
 257 $(obj)/%.o: objtool-enabled = $(if $(filter-out y%, \
 258         $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)
 259
 260 endif
 261
 262 ifdef CONFIG_TRIM_UNUSED_KSYMS
 263 cmd_gen_ksymdeps = \
 264         $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd
 265
 266 # List module undefined symbols
 267 undefined_syms = $(NM) $< | $(AWK) '$$1 == "U" { printf("%s%s", x++ ? " " : "", $$2) }';
 268 endif
 269
 270 define rule_cc_o_c
 271         $(call cmd_and_fixdep,cc_o_c)
 272         $(call cmd,gen_ksymdeps)
 273         $(call cmd,checksrc)
 274         $(call cmd,checkdoc)
 275         $(call cmd,gen_objtooldep)
 276         $(call cmd,modversions_c)
 277         $(call cmd,record_mcount)
 278 endef
 279
 280 define rule_as_o_S
 281         $(call cmd_and_fixdep,as_o_S)
 282         $(call cmd,gen_ksymdeps)
 283         $(call cmd,gen_objtooldep)
 284         $(call cmd,modversions_S)
 285 endef
 286
 287 # Built-in and composite module parts
 288 $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
 289         $(call if_changed_rule,cc_o_c)
 290         $(call cmd,force_checksrc)
 291
 292 ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
 293 # Module .o files may contain LLVM bitcode, compile them into native code
 294 # before ELF processing
 295 quiet_cmd_cc_prelink_modules = LD [M]  $@
 296       cmd_cc_prelink_modules =                                          \
 297         $(LD) $(ld_flags) -r -o $@                                      \
 298                $(shell [ -s $(@:.prelink.o=.o.symversions) ] &&         \
 299                        echo -T $(@:.prelink.o=.o.symversions))          \
 300                 --whole-archive $(filter-out FORCE,$^)                  \
 301                 $(cmd_objtool)
 302
 303 # objtool was skipped for LLVM bitcode, run it now that we have compiled
 304 # modules into native code
 305 $(obj)/%.prelink.o: objtool-enabled = y
 306 $(obj)/%.prelink.o: part-of-module := y
 307
 308 $(obj)/%.prelink.o: $(obj)/%.o FORCE
 309         $(call if_changed,cc_prelink_modules)
 310 endif
 311
 312 cmd_mod = { \
 313         echo $(if $($*-objs)$($*-y)$($*-m), $(addprefix $(obj)/, $($*-objs) $($*-y) $($*-m)), $(@:.mod=.o)); \
 314         $(undefined_syms) echo; \
 315         } > $@
 316
 317 $(obj)/%.mod: $(obj)/%$(mod-prelink-ext).o FORCE
 318         $(call if_changed,mod)
 319
 320 quiet_cmd_cc_lst_c = MKLST   $@
 321       cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
 322                      $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
 323                                      System.map $(OBJDUMP) > $@
 324
 325 $(obj)/%.lst: $(src)/%.c FORCE
 326         $(call if_changed_dep,cc_lst_c)
 327
 328 # Compile assembler sources (.S)
 329 # ---------------------------------------------------------------------------
 330
 331 # .S file exports must have their C prototypes defined in asm/asm-prototypes.h
 332 # or a file that it includes, in order to get versioned symbols. We build a
 333 # dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
 334 # the .S file (with trailing ';'), and run genksyms on that, to extract vers.
 335 #
 336 # This is convoluted. The .S file must first be preprocessed to run guards and
 337 # expand names, then the resulting exports must be constructed into plain
 338 # EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
 339 # to make the genksyms input.
 340 #
 341 # These mirror gensymtypes_c and co above, keep them in synch.
 342 cmd_gensymtypes_S =                                                         \
 343    { echo "\#include <linux/kernel.h>" ;                                    \
 344      echo "\#include <asm/asm-prototypes.h>" ;                              \
 345     $(CPP) $(a_flags) $< |                                                  \
 346      grep "\<___EXPORT_SYMBOL\>" |                                          \
 347      sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \
 348     $(CPP) -D__GENKSYMS__ $(c_flags) -xc - |                                \
 349     scripts/genksyms/genksyms $(if $(1), -T $(2))                           \
 350      $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS))                             \
 351      $(if $(KBUILD_PRESERVE),-p)                                            \
 352      -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
 353
 354 quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
 355 cmd_cc_symtypes_S =                                                         \
 356     $(call cmd_gensymtypes_S,true,$@) >/dev/null;                           \
 357     test -s $@ || rm -f $@
 358
 359 $(obj)/%.symtypes : $(src)/%.S FORCE
 360         $(call cmd,cc_symtypes_S)
 361
 362
 363 quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
 364 cmd_cpp_s_S       = $(CPP) $(a_flags) -o $@ $<
 365
 366 $(obj)/%.s: $(src)/%.S FORCE
 367         $(call if_changed_dep,cpp_s_S)
 368
 369 quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
 370       cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $< $(cmd_objtool)
 371
 372 ifdef CONFIG_ASM_MODVERSIONS
 373
 374 # versioning matches the C process described above, with difference that
 375 # we parse asm-prototypes.h C header to get function definitions.
 376
 377 cmd_modversions_S =                                                             \
 378         if $(OBJDUMP) -h $@ | grep -q __ksymtab; then                           \
 379                 $(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))  \
 380                     > $(@D)/.tmp_$(@F:.o=.ver);                                 \
 381                                                                                 \
 382                 $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@               \
 383                         -T $(@D)/.tmp_$(@F:.o=.ver);                            \
 384                 mv -f $(@D)/.tmp_$(@F) $@;                                      \
 385                 rm -f $(@D)/.tmp_$(@F:.o=.ver);                                 \
 386         fi
 387 endif
 388
 389 $(obj)/%.o: $(src)/%.S FORCE
 390         $(call if_changed_rule,as_o_S)
 391
 392 targets += $(filter-out $(subdir-builtin), $(real-obj-y))
 393 targets += $(filter-out $(subdir-modorder), $(real-obj-m))
 394 targets += $(real-dtb-y) $(lib-y) $(always-y) $(MAKECMDGOALS)
 395
 396 # Linker scripts preprocessor (.lds.S -> .lds)
 397 # ---------------------------------------------------------------------------
 398 quiet_cmd_cpp_lds_S = LDS     $@
 399       cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
 400                              -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
 401
 402 $(obj)/%.lds: $(src)/%.lds.S FORCE
 403         $(call if_changed_dep,cpp_lds_S)
 404
 405 # ASN.1 grammar
 406 # ---------------------------------------------------------------------------
 407 quiet_cmd_asn1_compiler = ASN.1   $(basename $@).[ch]
 408       cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
 409                                 $(basename $@).c $(basename $@).h
 410
 411 $(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
 412         $(call cmd,asn1_compiler)
 413
 414 # Build the compiled-in targets
 415 # ---------------------------------------------------------------------------
 416
 417 # To build objects in subdirs, we need to descend into the directories
 418 $(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ;
 419 $(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
 420
 421 # combine symversions for later processing
 422 ifeq ($(CONFIG_LTO_CLANG) $(CONFIG_MODVERSIONS),y y)
 423       cmd_update_lto_symversions =                                      \
 424         rm -f $@.symversions                                            \
 425         $(foreach n, $(filter-out FORCE,$^),                            \
 426                 $(if $(shell test -s $(n).symversions && echo y),       \
 427                         ; cat $(n).symversions >> $@.symversions))
 428 else
 429       cmd_update_lto_symversions = echo >/dev/null
 430 endif
 431
 432 #
 433 # Rule to compile a set of .o files into one .a file (without symbol table)
 434 #
 435
 436 quiet_cmd_ar_builtin = AR      $@
 437       cmd_ar_builtin = rm -f $@; $(AR) cDPrST $@ $(real-prereqs)
 438
 439 quiet_cmd_ar_and_symver = AR      $@
 440       cmd_ar_and_symver = $(cmd_update_lto_symversions); $(cmd_ar_builtin)
 441
 442 $(obj)/built-in.a: $(real-obj-y) FORCE
 443         $(call if_changed,ar_and_symver)
 444
 445 #
 446 # Rule to create modules.order file
 447 #
 448 # Create commands to either record .ko file or cat modules.order from
 449 # a subdirectory
 450 # Add $(obj-m) as the prerequisite to avoid updating the timestamp of
 451 # modules.order unless contained modules are updated.
 452
 453 cmd_modules_order = { $(foreach m, $(real-prereqs), \
 454         $(if $(filter %/modules.order, $m), cat $m, echo $(patsubst %.o,%.ko,$m));) :; } \
 455         | $(AWK) '!x[$$0]++' - > $@
 456
 457 $(obj)/modules.order: $(obj-m) FORCE
 458         $(call if_changed,modules_order)
 459
 460 #
 461 # Rule to compile a set of .o files into one .a file (with symbol table)
 462 #
 463 quiet_cmd_ar_lib = AR      $@
 464       cmd_ar_lib = $(cmd_update_lto_symversions); $(cmd_ar)
 465
 466 $(obj)/lib.a: $(lib-y) FORCE
 467         $(call if_changed,ar_lib)
 468
 469 # NOTE:
 470 # Do not replace $(filter %.o,^) with $(real-prereqs). When a single object
 471 # module is turned into a multi object module, $^ will contain header file
 472 # dependencies recorded in the .*.cmd file.
 473 ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
 474 quiet_cmd_link_multi-m = AR [M]  $@
 475 cmd_link_multi-m =                                              \
 476         $(cmd_update_lto_symversions);                          \
 477         rm -f $@;                                               \
 478         $(AR) cDPrsT $@ $(filter %.o,$^)
 479 else
 480 quiet_cmd_link_multi-m = LD [M]  $@
 481       cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(filter %.o,$^)
 482 endif
 483
 484 $(multi-obj-m): FORCE
 485         $(call if_changed,link_multi-m)
 486 $(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
 487
 488 targets += $(multi-obj-m)
 489 targets := $(filter-out $(PHONY), $(targets))
 490
 491 # Add intermediate targets:
 492 # When building objects with specific suffix patterns, add intermediate
 493 # targets that the final targets are derived from.
 494 intermediate_targets = $(foreach sfx, $(2), \
 495                                 $(patsubst %$(strip $(1)),%$(sfx), \
 496                                         $(filter %$(strip $(1)), $(targets))))
 497 # %.asn1.o <- %.asn1.[ch] <- %.asn1
 498 # %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
 499 # %.lex.o <- %.lex.c <- %.l
 500 # %.tab.o <- %.tab.[ch] <- %.y
 501 targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
 502            $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
 503            $(call intermediate_targets, .lex.o, .lex.c) \
 504            $(call intermediate_targets, .tab.o, .tab.c .tab.h)
 505
 506 # Build
 507 # ---------------------------------------------------------------------------
 508
 509 ifdef single-build
 510
 511 KBUILD_SINGLE_TARGETS := $(filter $(obj)/%, $(KBUILD_SINGLE_TARGETS))
 512
 513 curdir-single := $(sort $(foreach x, $(KBUILD_SINGLE_TARGETS), \
 514                         $(if $(filter $(x) $(basename $(x)).o, $(targets)), $(x))))
 515
 516 # Handle single targets without any rule: show "Nothing to be done for ..." or
 517 # "No rule to make target ..." depending on whether the target exists.
 518 unknown-single := $(filter-out $(addsuffix /%, $(subdir-ym)), \
 519                         $(filter-out $(curdir-single), $(KBUILD_SINGLE_TARGETS)))
 520
 521 single-subdirs := $(foreach d, $(subdir-ym), \
 522                         $(if $(filter $(d)/%, $(KBUILD_SINGLE_TARGETS)), $(d)))
 523
 524 __build: $(curdir-single) $(single-subdirs)
 525 ifneq ($(unknown-single),)
 526         $(Q)$(MAKE) -f /dev/null $(unknown-single)
 527 endif
 528         @:
 529
 530 ifeq ($(curdir-single),)
 531 # Nothing to do in this directory. Do not include any .*.cmd file for speed-up
 532 targets :=
 533 else
 534 targets += $(curdir-single)
 535 endif
 536
 537 else
 538
 539 __build: $(if $(KBUILD_BUILTIN), $(targets-for-builtin)) \
 540          $(if $(KBUILD_MODULES), $(targets-for-modules)) \
 541          $(subdir-ym) $(always-y)
 542         @:
 543
 544 endif
 545
 546 # Descending
 547 # ---------------------------------------------------------------------------
 548
 549 PHONY += $(subdir-ym)
 550 $(subdir-ym):
 551         $(Q)$(MAKE) $(build)=$@ \
 552         $(if $(filter $@/, $(KBUILD_SINGLE_TARGETS)),single-build=) \
 553         need-builtin=$(if $(filter $@/built-in.a, $(subdir-builtin)),1) \
 554         need-modorder=$(if $(filter $@/modules.order, $(subdir-modorder)),1)
 555
 556 # Add FORCE to the prequisites of a target to force it to be always rebuilt.
 557 # ---------------------------------------------------------------------------
 558
 559 PHONY += FORCE
 560
 561 FORCE:
 562
 563 # Read all saved command lines and dependencies for the $(targets) we
 564 # may be building above, using $(if_changed{,_dep}). As an
 565 # optimization, we don't need to read them if the target does not
 566 # exist, we will rebuild anyway in that case.
 567
 568 existing-targets := $(wildcard $(sort $(targets)))
 569
 570 -include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
 571
 572 # Create directories for object files if they do not exist
 573 obj-dirs := $(sort $(patsubst %/,%, $(dir $(targets))))
 574 # If targets exist, their directories apparently exist. Skip mkdir.
 575 existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
 576 obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
 577 ifneq ($(obj-dirs),)
 578 $(shell mkdir -p $(obj-dirs))
 579 endif
 580
 581 .PHONY: $(PHONY)