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