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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 :=
19targets :=
20subdir-y :=
21subdir-m :=
22EXTRA_AFLAGS :=
23EXTRA_CFLAGS :=
24EXTRA_CPPFLAGS :=
25EXTRA_LDFLAGS :=
26asflags-y :=
27ccflags-y :=
28cppflags-y :=
29ldflags-y :=
30
31subdir-asflags-y :=
32subdir-ccflags-y :=
33
34# Read auto.conf if it exists, otherwise ignore
35-include include/config/auto.conf
36
37include scripts/Kbuild.include
38
39# For backward compatibility check that these variables do not change
40save-cflags := $(CFLAGS)
41
42# The filename Kbuild has precedence over Makefile
43kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
44kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
45include $(kbuild-file)
46
47# If the save-* variables changed error out
48ifeq ($(KBUILD_NOPEDANTIC),)
49 ifneq ("$(save-cflags)","$(CFLAGS)")
50 $(error CFLAGS was changed in "$(kbuild-file)". Fix it to use ccflags-y)
51 endif
52endif
53
54include scripts/Makefile.lib
55
56ifdef host-progs
57ifneq ($(hostprogs-y),$(host-progs))
58$(warning kbuild: $(obj)/Makefile - Usage of host-progs is deprecated. Please replace with hostprogs-y!)
59hostprogs-y += $(host-progs)
60endif
61endif
62
63# Do not include host rules unless needed
64ifneq ($(hostprogs-y)$(hostprogs-m)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(hostcxxlibs-m),)
65include scripts/Makefile.host
66endif
67
68ifndef obj
69$(warning kbuild: Makefile.build is included improperly)
70endif
71
72# ===========================================================================
73
74ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
75lib-target := $(obj)/lib.a
76real-obj-y += $(obj)/lib-ksyms.o
77endif
78
79ifneq ($(strip $(real-obj-y) $(need-builtin)),)
80builtin-target := $(obj)/built-in.a
81endif
82
83modorder-target := $(obj)/modules.order
84
85# We keep a list of all modules in $(MODVERDIR)
86
87__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
88 $(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
89 $(subdir-ym) $(always)
90 @:
91
92# Linus' kernel sanity checking tool
93ifneq ($(KBUILD_CHECKSRC),0)
94 ifeq ($(KBUILD_CHECKSRC),2)
95 quiet_cmd_force_checksrc = CHECK $<
96 cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
97 else
98 quiet_cmd_checksrc = CHECK $<
99 cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
100 endif
101endif
102
103ifneq ($(KBUILD_ENABLE_EXTRA_GCC_CHECKS),)
104 cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $< ;
105endif
106
107# Do section mismatch analysis for each module/built-in.a
108ifdef CONFIG_DEBUG_SECTION_MISMATCH
109 cmd_secanalysis = ; scripts/mod/modpost $@
110endif
111
112# Compile C sources (.c)
113# ---------------------------------------------------------------------------
114
115# Default is built-in, unless we know otherwise
116modkern_cflags = \
117 $(if $(part-of-module), \
118 $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
119 $(KBUILD_CFLAGS_KERNEL) $(CFLAGS_KERNEL))
120quiet_modtag := $(empty) $(empty)
121
122$(real-obj-m) : part-of-module := y
123$(real-obj-m:.o=.i) : part-of-module := y
124$(real-obj-m:.o=.s) : part-of-module := y
125$(real-obj-m:.o=.lst): part-of-module := y
126
127$(real-obj-m) : quiet_modtag := [M]
128$(real-obj-m:.o=.i) : quiet_modtag := [M]
129$(real-obj-m:.o=.s) : quiet_modtag := [M]
130$(real-obj-m:.o=.lst): quiet_modtag := [M]
131
132$(obj-m) : quiet_modtag := [M]
133
134quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
135cmd_cc_s_c = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<
136
137$(obj)/%.s: $(src)/%.c FORCE
138 $(call if_changed_dep,cc_s_c)
139
140quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
141cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $<
142
143$(obj)/%.i: $(src)/%.c FORCE
144 $(call if_changed_dep,cpp_i_c)
145
146# These mirror gensymtypes_S and co below, keep them in synch.
147cmd_gensymtypes_c = \
148 $(CPP) -D__GENKSYMS__ $(c_flags) $< | \
149 $(GENKSYMS) $(if $(1), -T $(2)) \
150 $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX)) \
151 $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \
152 $(if $(KBUILD_PRESERVE),-p) \
153 -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
154
155quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
156cmd_cc_symtypes_c = \
157 set -e; \
158 $(call cmd_gensymtypes_c,true,$@) >/dev/null; \
159 test -s $@ || rm -f $@
160
161$(obj)/%.symtypes : $(src)/%.c FORCE
162 $(call cmd,cc_symtypes_c)
163
164# LLVM assembly
165# Generate .ll files from .c
166quiet_cmd_cc_ll_c = CC $(quiet_modtag) $@
167 cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
168
169$(obj)/%.ll: $(src)/%.c FORCE
170 $(call if_changed_dep,cc_ll_c)
171
172# C (.c) files
173# The C file is compiled and updated dependency information is generated.
174# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
175
176quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
177
178ifndef CONFIG_MODVERSIONS
179cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
180
181else
182# When module versioning is enabled the following steps are executed:
183# o compile a .tmp_<file>.o from <file>.c
184# o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
185# not export symbols, we just rename .tmp_<file>.o to <file>.o and
186# are done.
187# o otherwise, we calculate symbol versions using the good old
188# genksyms on the preprocessed source and postprocess them in a way
189# that they are usable as a linker script
190# o generate <file>.o from .tmp_<file>.o using the linker to
191# replace the unresolved symbols __crc_exported_symbol with
192# the actual value of the checksum generated by genksyms
193
194cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
195
196cmd_modversions_c = \
197 if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then \
198 $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
199 > $(@D)/.tmp_$(@F:.o=.ver); \
200 \
201 $(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) \
202 -T $(@D)/.tmp_$(@F:.o=.ver); \
203 rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver); \
204 else \
205 mv -f $(@D)/.tmp_$(@F) $@; \
206 fi;
207endif
208
209ifdef CONFIG_FTRACE_MCOUNT_RECORD
210ifdef BUILD_C_RECORDMCOUNT
211ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
212 RECORDMCOUNT_FLAGS = -w
213endif
214# Due to recursion, we must skip empty.o.
215# The empty.o file is created in the make process in order to determine
216# the target endianness and word size. It is made before all other C
217# files, including recordmcount.
218sub_cmd_record_mcount = \
219 if [ $(@) != "scripts/mod/empty.o" ]; then \
220 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
221 fi;
222recordmcount_source := $(srctree)/scripts/recordmcount.c \
223 $(srctree)/scripts/recordmcount.h
224else
225sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
226 "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
227 "$(if $(CONFIG_64BIT),64,32)" \
228 "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CFLAGS)" \
229 "$(LD)" "$(NM)" "$(RM)" "$(MV)" \
230 "$(if $(part-of-module),1,0)" "$(@)";
231recordmcount_source := $(srctree)/scripts/recordmcount.pl
232endif # BUILD_C_RECORDMCOUNT
233cmd_record_mcount = \
234 if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" = \
235 "$(CC_FLAGS_FTRACE)" ]; then \
236 $(sub_cmd_record_mcount) \
237 fi;
238endif # CONFIG_FTRACE_MCOUNT_RECORD
239
240ifdef CONFIG_STACK_VALIDATION
241ifneq ($(SKIP_STACK_VALIDATION),1)
242
243__objtool_obj := $(objtree)/tools/objtool/objtool
244
245objtool_args = $(if $(CONFIG_UNWINDER_ORC),orc generate,check)
246
247objtool_args += $(if $(part-of-module), --module,)
248
249ifndef CONFIG_FRAME_POINTER
250objtool_args += --no-fp
251endif
252ifdef CONFIG_GCOV_KERNEL
253objtool_args += --no-unreachable
254else
255objtool_args += $(call cc-ifversion, -lt, 0405, --no-unreachable)
256endif
257ifdef CONFIG_RETPOLINE
258ifneq ($(RETPOLINE_CFLAGS),)
259 objtool_args += --retpoline
260endif
261endif
262
263
264ifdef CONFIG_MODVERSIONS
265objtool_o = $(@D)/.tmp_$(@F)
266else
267objtool_o = $(@)
268endif
269
270# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
271# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
272# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
273cmd_objtool = $(if $(patsubst y%,, \
274 $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
275 $(__objtool_obj) $(objtool_args) "$(objtool_o)";)
276objtool_obj = $(if $(patsubst y%,, \
277 $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
278 $(__objtool_obj))
279
280endif # SKIP_STACK_VALIDATION
281endif # CONFIG_STACK_VALIDATION
282
283# Rebuild all objects when objtool changes, or is enabled/disabled.
284objtool_dep = $(objtool_obj) \
285 $(wildcard include/config/orc/unwinder.h \
286 include/config/stack/validation.h)
287
288define rule_cc_o_c
289 $(call echo-cmd,checksrc) $(cmd_checksrc) \
290 $(call cmd_and_fixdep,cc_o_c) \
291 $(cmd_checkdoc) \
292 $(call echo-cmd,objtool) $(cmd_objtool) \
293 $(cmd_modversions_c) \
294 $(call echo-cmd,record_mcount) $(cmd_record_mcount)
295endef
296
297define rule_as_o_S
298 $(call cmd_and_fixdep,as_o_S) \
299 $(call echo-cmd,objtool) $(cmd_objtool) \
300 $(cmd_modversions_S)
301endef
302
303# List module undefined symbols (or empty line if not enabled)
304ifdef CONFIG_TRIM_UNUSED_KSYMS
305cmd_undef_syms = $(NM) $@ | sed -n 's/^ *U //p' | xargs echo
306else
307cmd_undef_syms = echo
308endif
309
310# Built-in and composite module parts
311$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
312 $(call cmd,force_checksrc)
313 $(call if_changed_rule,cc_o_c)
314
315# Single-part modules are special since we need to mark them in $(MODVERDIR)
316
317$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
318 $(call cmd,force_checksrc)
319 $(call if_changed_rule,cc_o_c)
320 @{ echo $(@:.o=.ko); echo $@; \
321 $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
322
323quiet_cmd_cc_lst_c = MKLST $@
324 cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
325 $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
326 System.map $(OBJDUMP) > $@
327
328$(obj)/%.lst: $(src)/%.c FORCE
329 $(call if_changed_dep,cc_lst_c)
330
331# Compile assembler sources (.S)
332# ---------------------------------------------------------------------------
333
334modkern_aflags := $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL)
335
336$(real-obj-m) : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
337$(real-obj-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
338
339# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
340# or a file that it includes, in order to get versioned symbols. We build a
341# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
342# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
343#
344# This is convoluted. The .S file must first be preprocessed to run guards and
345# expand names, then the resulting exports must be constructed into plain
346# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
347# to make the genksyms input.
348#
349# These mirror gensymtypes_c and co above, keep them in synch.
350cmd_gensymtypes_S = \
351 (echo "\#include <linux/kernel.h>" ; \
352 echo "\#include <asm/asm-prototypes.h>" ; \
353 $(CPP) $(a_flags) $< | \
354 grep "\<___EXPORT_SYMBOL\>" | \
355 sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ) | \
356 $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | \
357 $(GENKSYMS) $(if $(1), -T $(2)) \
358 $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX)) \
359 $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \
360 $(if $(KBUILD_PRESERVE),-p) \
361 -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
362
363quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
364cmd_cc_symtypes_S = \
365 set -e; \
366 $(call cmd_gensymtypes_S,true,$@) >/dev/null; \
367 test -s $@ || rm -f $@
368
369$(obj)/%.symtypes : $(src)/%.S FORCE
370 $(call cmd,cc_symtypes_S)
371
372
373quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
374cmd_cpp_s_S = $(CPP) $(a_flags) -o $@ $<
375
376$(obj)/%.s: $(src)/%.S FORCE
377 $(call if_changed_dep,cpp_s_S)
378
379quiet_cmd_as_o_S = AS $(quiet_modtag) $@
380
381ifndef CONFIG_MODVERSIONS
382cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
383
384else
385
386ASM_PROTOTYPES := $(wildcard $(srctree)/arch/$(SRCARCH)/include/asm/asm-prototypes.h)
387
388ifeq ($(ASM_PROTOTYPES),)
389cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
390
391else
392
393# versioning matches the C process described above, with difference that
394# we parse asm-prototypes.h C header to get function definitions.
395
396cmd_as_o_S = $(CC) $(a_flags) -c -o $(@D)/.tmp_$(@F) $<
397
398cmd_modversions_S = \
399 if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then \
400 $(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
401 > $(@D)/.tmp_$(@F:.o=.ver); \
402 \
403 $(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) \
404 -T $(@D)/.tmp_$(@F:.o=.ver); \
405 rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver); \
406 else \
407 mv -f $(@D)/.tmp_$(@F) $@; \
408 fi;
409endif
410endif
411
412$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
413 $(call if_changed_rule,as_o_S)
414
415targets += $(filter-out $(subdir-obj-y), $(real-obj-y)) $(real-obj-m) $(lib-y)
416targets += $(extra-y) $(MAKECMDGOALS) $(always)
417
418# Linker scripts preprocessor (.lds.S -> .lds)
419# ---------------------------------------------------------------------------
420quiet_cmd_cpp_lds_S = LDS $@
421 cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
422 -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
423
424$(obj)/%.lds: $(src)/%.lds.S FORCE
425 $(call if_changed_dep,cpp_lds_S)
426
427# ASN.1 grammar
428# ---------------------------------------------------------------------------
429quiet_cmd_asn1_compiler = ASN.1 $@
430 cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
431 $(subst .h,.c,$@) $(subst .c,.h,$@)
432
433$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
434 $(call cmd,asn1_compiler)
435
436# Build the compiled-in targets
437# ---------------------------------------------------------------------------
438
439# To build objects in subdirs, we need to descend into the directories
440$(sort $(subdir-obj-y)): $(subdir-ym) ;
441
442#
443# Rule to compile a set of .o files into one .o file
444#
445ifdef builtin-target
446
447# built-in.a archives are made with no symbol table or index which
448# makes them small and fast, but unable to be used by the linker.
449# scripts/link-vmlinux.sh builds an aggregate built-in.a with a symbol
450# table and index.
451quiet_cmd_ar_builtin = AR $@
452 cmd_ar_builtin = rm -f $@; \
453 $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(filter $(real-obj-y), $^)
454
455$(builtin-target): $(real-obj-y) FORCE
456 $(call if_changed,ar_builtin)
457
458targets += $(builtin-target)
459endif # builtin-target
460
461#
462# Rule to create modules.order file
463#
464# Create commands to either record .ko file or cat modules.order from
465# a subdirectory
466modorder-cmds = \
467 $(foreach m, $(modorder), \
468 $(if $(filter %/modules.order, $m), \
469 cat $m;, echo kernel/$m;))
470
471$(modorder-target): $(subdir-ym) FORCE
472 $(Q)(cat /dev/null; $(modorder-cmds)) > $@
473
474#
475# Rule to compile a set of .o files into one .a file
476#
477ifdef lib-target
478quiet_cmd_link_l_target = AR $@
479
480# lib target archives do get a symbol table and index
481cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(lib-y)
482
483$(lib-target): $(lib-y) FORCE
484 $(call if_changed,link_l_target)
485
486targets += $(lib-target)
487
488dummy-object = $(obj)/.lib_exports.o
489ksyms-lds = $(dot-target).lds
490ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
491ref_prefix = EXTERN(_
492else
493ref_prefix = EXTERN(
494endif
495
496quiet_cmd_export_list = EXPORTS $@
497cmd_export_list = $(OBJDUMP) -h $< | \
498 sed -ne '/___ksymtab/s/.*+\([^ ]*\).*/$(ref_prefix)\1)/p' >$(ksyms-lds);\
499 rm -f $(dummy-object);\
500 echo | $(CC) $(a_flags) -c -o $(dummy-object) -x assembler -;\
501 $(LD) $(ld_flags) -r -o $@ -T $(ksyms-lds) $(dummy-object);\
502 rm $(dummy-object) $(ksyms-lds)
503
504$(obj)/lib-ksyms.o: $(lib-target) FORCE
505 $(call if_changed,export_list)
506
507targets += $(obj)/lib-ksyms.o
508
509endif
510
511#
512# Rule to link composite objects
513#
514# Composite objects are specified in kbuild makefile as follows:
515# <composite-object>-objs := <list of .o files>
516# or
517# <composite-object>-y := <list of .o files>
518# or
519# <composite-object>-m := <list of .o files>
520# The -m syntax only works if <composite object> is a module
521link_multi_deps = \
522$(filter $(addprefix $(obj)/, \
523$($(subst $(obj)/,,$(@:.o=-objs))) \
524$($(subst $(obj)/,,$(@:.o=-y))) \
525$($(subst $(obj)/,,$(@:.o=-m)))), $^)
526
527quiet_cmd_link_multi-m = LD [M] $@
528cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
529
530$(multi-used-m): FORCE
531 $(call if_changed,link_multi-m)
532 @{ echo $(@:.o=.ko); echo $(link_multi_deps); \
533 $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
534$(call multi_depend, $(multi-used-m), .o, -objs -y -m)
535
536targets += $(multi-used-m)
537targets := $(filter-out $(PHONY), $(targets))
538
539# Add intermediate targets:
540# When building objects with specific suffix patterns, add intermediate
541# targets that the final targets are derived from.
542intermediate_targets = $(foreach sfx, $(2), \
543 $(patsubst %$(strip $(1)),%$(sfx), \
544 $(filter %$(strip $(1)), $(targets))))
545# %.asn1.o <- %.asn1.[ch] <- %.asn1
546# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
547# %.lex.o <- %.lex.c <- %.l
548# %.tab.o <- %.tab.[ch] <- %.y
549targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
550 $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
551 $(call intermediate_targets, .lex.o, .lex.c) \
552 $(call intermediate_targets, .tab.o, .tab.c .tab.h)
553
554# Descending
555# ---------------------------------------------------------------------------
556
557PHONY += $(subdir-ym)
558$(subdir-ym):
559 $(Q)$(MAKE) $(build)=$@ need-builtin=$(if $(findstring $@,$(subdir-obj-y)),1)
560
561# Add FORCE to the prequisites of a target to force it to be always rebuilt.
562# ---------------------------------------------------------------------------
563
564PHONY += FORCE
565
566FORCE:
567
568# Read all saved command lines and dependencies for the $(targets) we
569# may be building above, using $(if_changed{,_dep}). As an
570# optimization, we don't need to read them if the target does not
571# exist, we will rebuild anyway in that case.
572
573cmd_files := $(wildcard $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd))
574
575ifneq ($(cmd_files),)
576 include $(cmd_files)
577endif
578
579ifneq ($(KBUILD_SRC),)
580# Create directories for object files if they do not exist
581obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets))))
582# If cmd_files exist, their directories apparently exist. Skip mkdir.
583exist-dirs := $(sort $(patsubst %/,%, $(dir $(cmd_files))))
584obj-dirs := $(strip $(filter-out $(exist-dirs), $(obj-dirs)))
585ifneq ($(obj-dirs),)
586$(shell mkdir -p $(obj-dirs))
587endif
588endif
589
590# Some files contained in $(targets) are intermediate artifacts.
591# We never want them to be removed automatically.
592.SECONDARY: $(targets)
593
594# Declare the contents of the .PHONY variable as phony. We keep that
595# information in a variable se we can use it in if_changed and friends.
596
597.PHONY: $(PHONY)
1# SPDX-License-Identifier: GPL-2.0
2# ==========================================================================
3# Building
4# ==========================================================================
5
6src := $(obj)
7
8PHONY := $(obj)/
9$(obj)/:
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 :=
29rustflags-y :=
30cppflags-y :=
31ldflags-y :=
32
33subdir-asflags-y :=
34subdir-ccflags-y :=
35
36# Read auto.conf if it exists, otherwise ignore
37-include include/config/auto.conf
38
39include $(srctree)/scripts/Kbuild.include
40include $(srctree)/scripts/Makefile.compiler
41include $(kbuild-file)
42include $(srctree)/scripts/Makefile.lib
43
44# Do not include hostprogs rules unless needed.
45# $(sort ...) is used here to remove duplicated words and excessive spaces.
46hostprogs := $(sort $(hostprogs))
47ifneq ($(hostprogs),)
48include $(srctree)/scripts/Makefile.host
49endif
50
51# Do not include userprogs rules unless needed.
52# $(sort ...) is used here to remove duplicated words and excessive spaces.
53userprogs := $(sort $(userprogs))
54ifneq ($(userprogs),)
55include $(srctree)/scripts/Makefile.userprogs
56endif
57
58ifndef obj
59$(warning kbuild: Makefile.build is included improperly)
60endif
61
62ifeq ($(need-modorder),)
63ifneq ($(obj-m),)
64$(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
65$(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)
66endif
67endif
68
69# ===========================================================================
70
71# subdir-builtin and subdir-modorder may contain duplications. Use $(sort ...)
72subdir-builtin := $(sort $(filter %/built-in.a, $(real-obj-y)))
73subdir-modorder := $(sort $(filter %/modules.order, $(obj-m)))
74
75targets-for-builtin := $(extra-y)
76
77ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
78targets-for-builtin += $(obj)/lib.a
79endif
80
81ifdef need-builtin
82targets-for-builtin += $(obj)/built-in.a
83endif
84
85targets-for-modules := $(foreach x, o mod $(if $(CONFIG_TRIM_UNUSED_KSYMS), usyms), \
86 $(patsubst %.o, %.$x, $(filter %.o, $(obj-m))))
87
88ifdef need-modorder
89targets-for-modules += $(obj)/modules.order
90endif
91
92targets += $(targets-for-builtin) $(targets-for-modules)
93
94# Linus' kernel sanity checking tool
95ifeq ($(KBUILD_CHECKSRC),1)
96 quiet_cmd_checksrc = CHECK $<
97 cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
98else ifeq ($(KBUILD_CHECKSRC),2)
99 quiet_cmd_force_checksrc = CHECK $<
100 cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
101endif
102
103ifneq ($(KBUILD_EXTRA_WARN),)
104 cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $<
105endif
106
107# Compile C sources (.c)
108# ---------------------------------------------------------------------------
109
110quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
111 cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) -fverbose-asm -S -o $@ $<
112
113$(obj)/%.s: $(src)/%.c FORCE
114 $(call if_changed_dep,cc_s_c)
115
116quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
117cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $<
118
119$(obj)/%.i: $(src)/%.c FORCE
120 $(call if_changed_dep,cpp_i_c)
121
122genksyms = scripts/genksyms/genksyms \
123 $(if $(1), -T $(2)) \
124 $(if $(KBUILD_PRESERVE), -p) \
125 -r $(or $(wildcard $(2:.symtypes=.symref)), /dev/null)
126
127# These mirror gensymtypes_S and co below, keep them in synch.
128cmd_gensymtypes_c = $(CPP) -D__GENKSYMS__ $(c_flags) $< | $(genksyms)
129
130quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
131 cmd_cc_symtypes_c = $(call cmd_gensymtypes_c,true,$@) >/dev/null
132
133$(obj)/%.symtypes : $(src)/%.c FORCE
134 $(call cmd,cc_symtypes_c)
135
136# LLVM assembly
137# Generate .ll files from .c
138quiet_cmd_cc_ll_c = CC $(quiet_modtag) $@
139 cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -fno-discard-value-names -o $@ $<
140
141$(obj)/%.ll: $(src)/%.c FORCE
142 $(call if_changed_dep,cc_ll_c)
143
144# C (.c) files
145# The C file is compiled and updated dependency information is generated.
146# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
147
148is-single-obj-m = $(and $(part-of-module),$(filter $@, $(obj-m)),y)
149
150# When a module consists of a single object, there is no reason to keep LLVM IR.
151# Make $(LD) covert LLVM IR to ELF here.
152ifdef CONFIG_LTO_CLANG
153cmd_ld_single_m = $(if $(is-single-obj-m), ; $(LD) $(ld_flags) -r -o $(tmp-target) $@; mv $(tmp-target) $@)
154endif
155
156quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
157 cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< \
158 $(cmd_ld_single_m) \
159 $(cmd_objtool)
160
161ifdef CONFIG_MODVERSIONS
162# When module versioning is enabled the following steps are executed:
163# o compile a <file>.o from <file>.c
164# o if <file>.o doesn't contain a __ksymtab version, i.e. does
165# not export symbols, it's done.
166# o otherwise, we calculate symbol versions using the good old
167# genksyms on the preprocessed source and dump them into the .cmd file.
168# o modpost will extract versions from that file and create *.c files that will
169# be compiled and linked to the kernel and/or modules.
170
171gen_symversions = \
172 if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then \
173 $(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
174 >> $(dot-target).cmd; \
175 fi
176
177cmd_gen_symversions_c = $(call gen_symversions,c)
178
179endif
180
181ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
182# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
183ifdef BUILD_C_RECORDMCOUNT
184ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
185 RECORDMCOUNT_FLAGS = -w
186endif
187# Due to recursion, we must skip empty.o.
188# The empty.o file is created in the make process in order to determine
189# the target endianness and word size. It is made before all other C
190# files, including recordmcount.
191sub_cmd_record_mcount = \
192 if [ $(@) != "scripts/mod/empty.o" ]; then \
193 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
194 fi;
195recordmcount_source := $(srctree)/scripts/recordmcount.c \
196 $(srctree)/scripts/recordmcount.h
197else
198sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
199 "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
200 "$(if $(CONFIG_64BIT),64,32)" \
201 "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
202 "$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
203 "$(if $(part-of-module),1,0)" "$(@)";
204recordmcount_source := $(srctree)/scripts/recordmcount.pl
205endif # BUILD_C_RECORDMCOUNT
206cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
207 $(sub_cmd_record_mcount))
208endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
209
210# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
211# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
212# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
213
214is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)
215
216$(obj)/%.o: objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y))
217
218ifdef CONFIG_TRIM_UNUSED_KSYMS
219cmd_gen_ksymdeps = \
220 $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd
221endif
222
223cmd_check_local_export = $(srctree)/scripts/check-local-export $@
224
225ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
226cmd_warn_shared_object = $(if $(word 2, $(modname-multi)),$(warning $(kbuild-file): $*.o is added to multiple modules: $(modname-multi)))
227endif
228
229define rule_cc_o_c
230 $(call cmd_and_fixdep,cc_o_c)
231 $(call cmd,gen_ksymdeps)
232 $(call cmd,check_local_export)
233 $(call cmd,checksrc)
234 $(call cmd,checkdoc)
235 $(call cmd,gen_objtooldep)
236 $(call cmd,gen_symversions_c)
237 $(call cmd,record_mcount)
238 $(call cmd,warn_shared_object)
239endef
240
241define rule_as_o_S
242 $(call cmd_and_fixdep,as_o_S)
243 $(call cmd,gen_ksymdeps)
244 $(call cmd,check_local_export)
245 $(call cmd,gen_objtooldep)
246 $(call cmd,gen_symversions_S)
247 $(call cmd,warn_shared_object)
248endef
249
250# Built-in and composite module parts
251$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
252 $(call if_changed_rule,cc_o_c)
253 $(call cmd,force_checksrc)
254
255# To make this rule robust against "Argument list too long" error,
256# ensure to add $(obj)/ prefix by a shell command.
257cmd_mod = printf '%s\n' $(call real-search, $*.o, .o, -objs -y -m) | \
258 $(AWK) '!x[$$0]++ { print("$(obj)/"$$0) }' > $@
259
260$(obj)/%.mod: FORCE
261 $(call if_changed,mod)
262
263# List module undefined symbols
264cmd_undefined_syms = $(NM) $< | sed -n 's/^ *U //p' > $@
265
266$(obj)/%.usyms: $(obj)/%.o FORCE
267 $(call if_changed,undefined_syms)
268
269quiet_cmd_cc_lst_c = MKLST $@
270 cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
271 $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
272 System.map $(OBJDUMP) > $@
273
274$(obj)/%.lst: $(src)/%.c FORCE
275 $(call if_changed_dep,cc_lst_c)
276
277# Compile Rust sources (.rs)
278# ---------------------------------------------------------------------------
279
280rust_allowed_features := core_ffi_c
281
282rust_common_cmd = \
283 RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \
284 -Zallow-features=$(rust_allowed_features) \
285 -Zcrate-attr=no_std \
286 -Zcrate-attr='feature($(rust_allowed_features))' \
287 --extern alloc --extern kernel \
288 --crate-type rlib --out-dir $(obj) -L $(objtree)/rust/ \
289 --crate-name $(basename $(notdir $@))
290
291rust_handle_depfile = \
292 mv $(obj)/$(basename $(notdir $@)).d $(depfile); \
293 sed -i '/^\#/d' $(depfile)
294
295# `--emit=obj`, `--emit=asm` and `--emit=llvm-ir` imply a single codegen unit
296# will be used. We explicitly request `-Ccodegen-units=1` in any case, and
297# the compiler shows a warning if it is not 1. However, if we ever stop
298# requesting it explicitly and we start using some other `--emit` that does not
299# imply it (and for which codegen is performed), then we would be out of sync,
300# i.e. the outputs we would get for the different single targets (e.g. `.ll`)
301# would not match each other.
302
303quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
304 cmd_rustc_o_rs = \
305 $(rust_common_cmd) --emit=dep-info,obj $<; \
306 $(rust_handle_depfile)
307
308$(obj)/%.o: $(src)/%.rs FORCE
309 $(call if_changed_dep,rustc_o_rs)
310
311quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
312 cmd_rustc_rsi_rs = \
313 $(rust_common_cmd) --emit=dep-info -Zunpretty=expanded $< >$@; \
314 command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) $@; \
315 $(rust_handle_depfile)
316
317$(obj)/%.rsi: $(src)/%.rs FORCE
318 $(call if_changed_dep,rustc_rsi_rs)
319
320quiet_cmd_rustc_s_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
321 cmd_rustc_s_rs = \
322 $(rust_common_cmd) --emit=dep-info,asm $<; \
323 $(rust_handle_depfile)
324
325$(obj)/%.s: $(src)/%.rs FORCE
326 $(call if_changed_dep,rustc_s_rs)
327
328quiet_cmd_rustc_ll_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
329 cmd_rustc_ll_rs = \
330 $(rust_common_cmd) --emit=dep-info,llvm-ir $<; \
331 $(rust_handle_depfile)
332
333$(obj)/%.ll: $(src)/%.rs FORCE
334 $(call if_changed_dep,rustc_ll_rs)
335
336# Compile assembler sources (.S)
337# ---------------------------------------------------------------------------
338
339# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
340# or a file that it includes, in order to get versioned symbols. We build a
341# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
342# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
343#
344# This is convoluted. The .S file must first be preprocessed to run guards and
345# expand names, then the resulting exports must be constructed into plain
346# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
347# to make the genksyms input.
348#
349# These mirror gensymtypes_c and co above, keep them in synch.
350cmd_gensymtypes_S = \
351 { echo "\#include <linux/kernel.h>" ; \
352 echo "\#include <asm/asm-prototypes.h>" ; \
353 $(CPP) $(a_flags) $< | \
354 grep "\<___EXPORT_SYMBOL\>" | \
355 sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \
356 $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | $(genksyms)
357
358quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
359 cmd_cc_symtypes_S = $(call cmd_gensymtypes_S,true,$@) >/dev/null
360
361$(obj)/%.symtypes : $(src)/%.S FORCE
362 $(call cmd,cc_symtypes_S)
363
364
365quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
366cmd_cpp_s_S = $(CPP) $(a_flags) -o $@ $<
367
368$(obj)/%.s: $(src)/%.S FORCE
369 $(call if_changed_dep,cpp_s_S)
370
371quiet_cmd_as_o_S = AS $(quiet_modtag) $@
372 cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $< $(cmd_objtool)
373
374ifdef CONFIG_ASM_MODVERSIONS
375
376# versioning matches the C process described above, with difference that
377# we parse asm-prototypes.h C header to get function definitions.
378
379cmd_gen_symversions_S = $(call gen_symversions,S)
380
381endif
382
383$(obj)/%.o: $(src)/%.S FORCE
384 $(call if_changed_rule,as_o_S)
385
386targets += $(filter-out $(subdir-builtin), $(real-obj-y))
387targets += $(filter-out $(subdir-modorder), $(real-obj-m))
388targets += $(real-dtb-y) $(lib-y) $(always-y)
389
390# Linker scripts preprocessor (.lds.S -> .lds)
391# ---------------------------------------------------------------------------
392quiet_cmd_cpp_lds_S = LDS $@
393 cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
394 -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
395
396$(obj)/%.lds: $(src)/%.lds.S FORCE
397 $(call if_changed_dep,cpp_lds_S)
398
399# ASN.1 grammar
400# ---------------------------------------------------------------------------
401quiet_cmd_asn1_compiler = ASN.1 $(basename $@).[ch]
402 cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
403 $(basename $@).c $(basename $@).h
404
405$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
406 $(call cmd,asn1_compiler)
407
408# Build the compiled-in targets
409# ---------------------------------------------------------------------------
410
411# To build objects in subdirs, we need to descend into the directories
412$(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ;
413$(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
414
415#
416# Rule to compile a set of .o files into one .a file (without symbol table)
417#
418# To make this rule robust against "Argument list too long" error,
419# remove $(obj)/ prefix, and restore it by a shell command.
420
421quiet_cmd_ar_builtin = AR $@
422 cmd_ar_builtin = rm -f $@; \
423 $(if $(real-prereqs), printf "$(obj)/%s " $(patsubst $(obj)/%,%,$(real-prereqs)) | xargs) \
424 $(AR) cDPrST $@
425
426$(obj)/built-in.a: $(real-obj-y) FORCE
427 $(call if_changed,ar_builtin)
428
429#
430# Rule to create modules.order file
431#
432# Create commands to either record .ko file or cat modules.order from
433# a subdirectory
434# Add $(obj-m) as the prerequisite to avoid updating the timestamp of
435# modules.order unless contained modules are updated.
436
437cmd_modules_order = { $(foreach m, $(real-prereqs), \
438 $(if $(filter %/modules.order, $m), cat $m, echo $m);) :; } \
439 > $@
440
441$(obj)/modules.order: $(obj-m) FORCE
442 $(call if_changed,modules_order)
443
444#
445# Rule to compile a set of .o files into one .a file (with symbol table)
446#
447
448$(obj)/lib.a: $(lib-y) FORCE
449 $(call if_changed,ar)
450
451quiet_cmd_ld_multi_m = LD [M] $@
452 cmd_ld_multi_m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@) $(cmd_objtool)
453
454define rule_ld_multi_m
455 $(call cmd_and_savecmd,ld_multi_m)
456 $(call cmd,gen_objtooldep)
457endef
458
459$(multi-obj-m): objtool-enabled := $(delay-objtool)
460$(multi-obj-m): part-of-module := y
461$(multi-obj-m): %.o: %.mod FORCE
462 $(call if_changed_rule,ld_multi_m)
463$(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
464
465# Add intermediate targets:
466# When building objects with specific suffix patterns, add intermediate
467# targets that the final targets are derived from.
468intermediate_targets = $(foreach sfx, $(2), \
469 $(patsubst %$(strip $(1)),%$(sfx), \
470 $(filter %$(strip $(1)), $(targets))))
471# %.asn1.o <- %.asn1.[ch] <- %.asn1
472# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
473# %.dtbo.o <- %.dtbo.S <- %.dtbo <- %.dtso
474# %.lex.o <- %.lex.c <- %.l
475# %.tab.o <- %.tab.[ch] <- %.y
476targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
477 $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
478 $(call intermediate_targets, .dtbo.o, .dtbo.S .dtbo) \
479 $(call intermediate_targets, .lex.o, .lex.c) \
480 $(call intermediate_targets, .tab.o, .tab.c .tab.h)
481
482# Build
483# ---------------------------------------------------------------------------
484
485$(obj)/: $(if $(KBUILD_BUILTIN), $(targets-for-builtin)) \
486 $(if $(KBUILD_MODULES), $(targets-for-modules)) \
487 $(subdir-ym) $(always-y)
488 @:
489
490# Single targets
491# ---------------------------------------------------------------------------
492
493single-subdirs := $(foreach d, $(subdir-ym), $(if $(filter $d/%, $(MAKECMDGOALS)), $d))
494single-subdir-goals := $(filter $(addsuffix /%, $(single-subdirs)), $(MAKECMDGOALS))
495
496$(single-subdir-goals): $(single-subdirs)
497 @:
498
499# Descending
500# ---------------------------------------------------------------------------
501
502PHONY += $(subdir-ym)
503$(subdir-ym):
504 $(Q)$(MAKE) $(build)=$@ \
505 need-builtin=$(if $(filter $@/built-in.a, $(subdir-builtin)),1) \
506 need-modorder=$(if $(filter $@/modules.order, $(subdir-modorder)),1) \
507 $(filter $@/%, $(single-subdir-goals))
508
509# Add FORCE to the prequisites of a target to force it to be always rebuilt.
510# ---------------------------------------------------------------------------
511
512PHONY += FORCE
513
514FORCE:
515
516targets += $(filter-out $(single-subdir-goals), $(MAKECMDGOALS))
517targets := $(filter-out $(PHONY), $(targets))
518
519# Read all saved command lines and dependencies for the $(targets) we
520# may be building above, using $(if_changed{,_dep}). As an
521# optimization, we don't need to read them if the target does not
522# exist, we will rebuild anyway in that case.
523
524existing-targets := $(wildcard $(sort $(targets)))
525
526-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
527
528# Create directories for object files if they do not exist
529obj-dirs := $(sort $(patsubst %/,%, $(dir $(targets))))
530# If targets exist, their directories apparently exist. Skip mkdir.
531existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
532obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
533ifneq ($(obj-dirs),)
534$(shell mkdir -p $(obj-dirs))
535endif
536
537.PHONY: $(PHONY)