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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# The filename Kbuild has precedence over Makefile
40kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
41kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
42include $(kbuild-file)
43
44include scripts/Makefile.lib
45
46# Do not include host rules unless needed
47ifneq ($(hostprogs-y)$(hostprogs-m)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(hostcxxlibs-m),)
48include scripts/Makefile.host
49endif
50
51ifndef obj
52$(warning kbuild: Makefile.build is included improperly)
53endif
54
55# ===========================================================================
56
57ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
58lib-target := $(obj)/lib.a
59real-obj-y += $(obj)/lib-ksyms.o
60endif
61
62ifneq ($(strip $(real-obj-y) $(need-builtin)),)
63builtin-target := $(obj)/built-in.a
64endif
65
66modorder-target := $(obj)/modules.order
67
68# We keep a list of all modules in $(MODVERDIR)
69
70__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
71 $(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
72 $(subdir-ym) $(always)
73 @:
74
75# Linus' kernel sanity checking tool
76ifeq ($(KBUILD_CHECKSRC),1)
77 quiet_cmd_checksrc = CHECK $<
78 cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
79else ifeq ($(KBUILD_CHECKSRC),2)
80 quiet_cmd_force_checksrc = CHECK $<
81 cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
82endif
83
84ifneq ($(KBUILD_ENABLE_EXTRA_GCC_CHECKS),)
85 cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $< ;
86endif
87
88# Do section mismatch analysis for each module/built-in.a
89ifdef CONFIG_DEBUG_SECTION_MISMATCH
90 cmd_secanalysis = ; scripts/mod/modpost $@
91endif
92
93# Compile C sources (.c)
94# ---------------------------------------------------------------------------
95
96# Default is built-in, unless we know otherwise
97modkern_cflags = \
98 $(if $(part-of-module), \
99 $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE), \
100 $(KBUILD_CFLAGS_KERNEL) $(CFLAGS_KERNEL))
101quiet_modtag := $(empty) $(empty)
102
103$(real-obj-m) : part-of-module := y
104$(real-obj-m:.o=.i) : part-of-module := y
105$(real-obj-m:.o=.s) : part-of-module := y
106$(real-obj-m:.o=.lst): part-of-module := y
107
108$(real-obj-m) : quiet_modtag := [M]
109$(real-obj-m:.o=.i) : quiet_modtag := [M]
110$(real-obj-m:.o=.s) : quiet_modtag := [M]
111$(real-obj-m:.o=.lst): quiet_modtag := [M]
112
113$(obj-m) : quiet_modtag := [M]
114
115quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
116cmd_cc_s_c = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<
117
118$(obj)/%.s: $(src)/%.c FORCE
119 $(call if_changed_dep,cc_s_c)
120
121quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
122cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $<
123
124$(obj)/%.i: $(src)/%.c FORCE
125 $(call if_changed_dep,cpp_i_c)
126
127# These mirror gensymtypes_S and co below, keep them in synch.
128cmd_gensymtypes_c = \
129 $(CPP) -D__GENKSYMS__ $(c_flags) $< | \
130 $(GENKSYMS) $(if $(1), -T $(2)) \
131 $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \
132 $(if $(KBUILD_PRESERVE),-p) \
133 -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
134
135quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
136cmd_cc_symtypes_c = \
137 set -e; \
138 $(call cmd_gensymtypes_c,true,$@) >/dev/null; \
139 test -s $@ || rm -f $@
140
141$(obj)/%.symtypes : $(src)/%.c FORCE
142 $(call cmd,cc_symtypes_c)
143
144# LLVM assembly
145# Generate .ll files from .c
146quiet_cmd_cc_ll_c = CC $(quiet_modtag) $@
147 cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
148
149$(obj)/%.ll: $(src)/%.c FORCE
150 $(call if_changed_dep,cc_ll_c)
151
152# C (.c) files
153# The C file is compiled and updated dependency information is generated.
154# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
155
156quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
157 cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
158
159ifdef CONFIG_MODVERSIONS
160# When module versioning is enabled the following steps are executed:
161# o compile a <file>.o from <file>.c
162# o if <file>.o doesn't contain a __ksymtab version, i.e. does
163# not export symbols, it's done.
164# o otherwise, we calculate symbol versions using the good old
165# genksyms on the preprocessed source and postprocess them in a way
166# that they are usable as a linker script
167# o generate .tmp_<file>.o from <file>.o using the linker to
168# replace the unresolved symbols __crc_exported_symbol with
169# the actual value of the checksum generated by genksyms
170# o remove .tmp_<file>.o to <file>.o
171
172cmd_modversions_c = \
173 if $(OBJDUMP) -h $@ | grep -q __ksymtab; then \
174 $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
175 > $(@D)/.tmp_$(@F:.o=.ver); \
176 \
177 $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ \
178 -T $(@D)/.tmp_$(@F:.o=.ver); \
179 mv -f $(@D)/.tmp_$(@F) $@; \
180 rm -f $(@D)/.tmp_$(@F:.o=.ver); \
181 fi;
182endif
183
184ifdef CONFIG_FTRACE_MCOUNT_RECORD
185ifndef CC_USING_RECORD_MCOUNT
186# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
187ifdef BUILD_C_RECORDMCOUNT
188ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
189 RECORDMCOUNT_FLAGS = -w
190endif
191# Due to recursion, we must skip empty.o.
192# The empty.o file is created in the make process in order to determine
193# the target endianness and word size. It is made before all other C
194# files, including recordmcount.
195sub_cmd_record_mcount = \
196 if [ $(@) != "scripts/mod/empty.o" ]; then \
197 $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
198 fi;
199recordmcount_source := $(srctree)/scripts/recordmcount.c \
200 $(srctree)/scripts/recordmcount.h
201else
202sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
203 "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
204 "$(if $(CONFIG_64BIT),64,32)" \
205 "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
206 "$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
207 "$(if $(part-of-module),1,0)" "$(@)";
208recordmcount_source := $(srctree)/scripts/recordmcount.pl
209endif # BUILD_C_RECORDMCOUNT
210cmd_record_mcount = \
211 if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" = \
212 "$(CC_FLAGS_FTRACE)" ]; then \
213 $(sub_cmd_record_mcount) \
214 fi;
215endif # CC_USING_RECORD_MCOUNT
216endif # CONFIG_FTRACE_MCOUNT_RECORD
217
218ifdef CONFIG_STACK_VALIDATION
219ifneq ($(SKIP_STACK_VALIDATION),1)
220
221__objtool_obj := $(objtree)/tools/objtool/objtool
222
223objtool_args = $(if $(CONFIG_UNWINDER_ORC),orc generate,check)
224
225objtool_args += $(if $(part-of-module), --module,)
226
227ifndef CONFIG_FRAME_POINTER
228objtool_args += --no-fp
229endif
230ifdef CONFIG_GCOV_KERNEL
231objtool_args += --no-unreachable
232endif
233ifdef CONFIG_RETPOLINE
234ifneq ($(RETPOLINE_CFLAGS),)
235 objtool_args += --retpoline
236endif
237endif
238
239# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
240# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
241# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
242cmd_objtool = $(if $(patsubst y%,, \
243 $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
244 $(__objtool_obj) $(objtool_args) $@;)
245objtool_obj = $(if $(patsubst y%,, \
246 $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
247 $(__objtool_obj))
248
249endif # SKIP_STACK_VALIDATION
250endif # CONFIG_STACK_VALIDATION
251
252# Rebuild all objects when objtool changes, or is enabled/disabled.
253objtool_dep = $(objtool_obj) \
254 $(wildcard include/config/orc/unwinder.h \
255 include/config/stack/validation.h)
256
257ifdef CONFIG_TRIM_UNUSED_KSYMS
258cmd_gen_ksymdeps = \
259 $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd;
260endif
261
262define rule_cc_o_c
263 $(call cmd,checksrc)
264 $(call cmd_and_fixdep,cc_o_c)
265 $(call cmd,gen_ksymdeps)
266 $(call cmd,checkdoc)
267 $(call cmd,objtool)
268 $(call cmd,modversions_c)
269 $(call cmd,record_mcount)
270endef
271
272define rule_as_o_S
273 $(call cmd_and_fixdep,as_o_S)
274 $(call cmd,gen_ksymdeps)
275 $(call cmd,objtool)
276 $(call cmd,modversions_S)
277endef
278
279# List module undefined symbols (or empty line if not enabled)
280ifdef CONFIG_TRIM_UNUSED_KSYMS
281cmd_undef_syms = $(NM) $@ | sed -n 's/^ *U //p' | xargs echo
282else
283cmd_undef_syms = echo
284endif
285
286# Built-in and composite module parts
287$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
288 $(call cmd,force_checksrc)
289 $(call if_changed_rule,cc_o_c)
290
291# Single-part modules are special since we need to mark them in $(MODVERDIR)
292
293$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
294 $(call cmd,force_checksrc)
295 $(call if_changed_rule,cc_o_c)
296 @{ echo $(@:.o=.ko); echo $@; \
297 $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
298
299quiet_cmd_cc_lst_c = MKLST $@
300 cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
301 $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
302 System.map $(OBJDUMP) > $@
303
304$(obj)/%.lst: $(src)/%.c FORCE
305 $(call if_changed_dep,cc_lst_c)
306
307# Compile assembler sources (.S)
308# ---------------------------------------------------------------------------
309
310modkern_aflags := $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL)
311
312$(real-obj-m) : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
313$(real-obj-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
314
315# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
316# or a file that it includes, in order to get versioned symbols. We build a
317# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
318# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
319#
320# This is convoluted. The .S file must first be preprocessed to run guards and
321# expand names, then the resulting exports must be constructed into plain
322# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
323# to make the genksyms input.
324#
325# These mirror gensymtypes_c and co above, keep them in synch.
326cmd_gensymtypes_S = \
327 (echo "\#include <linux/kernel.h>" ; \
328 echo "\#include <asm/asm-prototypes.h>" ; \
329 $(CPP) $(a_flags) $< | \
330 grep "\<___EXPORT_SYMBOL\>" | \
331 sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ) | \
332 $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | \
333 $(GENKSYMS) $(if $(1), -T $(2)) \
334 $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \
335 $(if $(KBUILD_PRESERVE),-p) \
336 -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
337
338quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
339cmd_cc_symtypes_S = \
340 set -e; \
341 $(call cmd_gensymtypes_S,true,$@) >/dev/null; \
342 test -s $@ || rm -f $@
343
344$(obj)/%.symtypes : $(src)/%.S FORCE
345 $(call cmd,cc_symtypes_S)
346
347
348quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
349cmd_cpp_s_S = $(CPP) $(a_flags) -o $@ $<
350
351$(obj)/%.s: $(src)/%.S FORCE
352 $(call if_changed_dep,cpp_s_S)
353
354quiet_cmd_as_o_S = AS $(quiet_modtag) $@
355 cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
356
357ifdef CONFIG_MODVERSIONS
358
359ASM_PROTOTYPES := $(wildcard $(srctree)/arch/$(SRCARCH)/include/asm/asm-prototypes.h)
360
361ifneq ($(ASM_PROTOTYPES),)
362
363# versioning matches the C process described above, with difference that
364# we parse asm-prototypes.h C header to get function definitions.
365
366cmd_modversions_S = \
367 if $(OBJDUMP) -h $@ | grep -q __ksymtab; then \
368 $(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
369 > $(@D)/.tmp_$(@F:.o=.ver); \
370 \
371 $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ \
372 -T $(@D)/.tmp_$(@F:.o=.ver); \
373 mv -f $(@D)/.tmp_$(@F) $@; \
374 rm -f $(@D)/.tmp_$(@F:.o=.ver); \
375 fi;
376endif
377endif
378
379$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
380 $(call if_changed_rule,as_o_S)
381
382targets += $(filter-out $(subdir-obj-y), $(real-obj-y)) $(real-obj-m) $(lib-y)
383targets += $(extra-y) $(MAKECMDGOALS) $(always)
384
385# Linker scripts preprocessor (.lds.S -> .lds)
386# ---------------------------------------------------------------------------
387quiet_cmd_cpp_lds_S = LDS $@
388 cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
389 -D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
390
391$(obj)/%.lds: $(src)/%.lds.S FORCE
392 $(call if_changed_dep,cpp_lds_S)
393
394# ASN.1 grammar
395# ---------------------------------------------------------------------------
396quiet_cmd_asn1_compiler = ASN.1 $@
397 cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
398 $(subst .h,.c,$@) $(subst .c,.h,$@)
399
400$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
401 $(call cmd,asn1_compiler)
402
403# Build the compiled-in targets
404# ---------------------------------------------------------------------------
405
406# To build objects in subdirs, we need to descend into the directories
407$(sort $(subdir-obj-y)): $(subdir-ym) ;
408
409#
410# Rule to compile a set of .o files into one .o file
411#
412ifdef builtin-target
413
414# built-in.a archives are made with no symbol table or index which
415# makes them small and fast, but unable to be used by the linker.
416# scripts/link-vmlinux.sh builds an aggregate built-in.a with a symbol
417# table and index.
418quiet_cmd_ar_builtin = AR $@
419 cmd_ar_builtin = rm -f $@; \
420 $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(filter $(real-obj-y), $^)
421
422$(builtin-target): $(real-obj-y) FORCE
423 $(call if_changed,ar_builtin)
424
425targets += $(builtin-target)
426endif # builtin-target
427
428#
429# Rule to create modules.order file
430#
431# Create commands to either record .ko file or cat modules.order from
432# a subdirectory
433modorder-cmds = \
434 $(foreach m, $(modorder), \
435 $(if $(filter %/modules.order, $m), \
436 cat $m;, echo kernel/$m;))
437
438$(modorder-target): $(subdir-ym) FORCE
439 $(Q)(cat /dev/null; $(modorder-cmds)) > $@
440
441#
442# Rule to compile a set of .o files into one .a file
443#
444ifdef lib-target
445quiet_cmd_link_l_target = AR $@
446
447# lib target archives do get a symbol table and index
448cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(lib-y)
449
450$(lib-target): $(lib-y) FORCE
451 $(call if_changed,link_l_target)
452
453targets += $(lib-target)
454
455dummy-object = $(obj)/.lib_exports.o
456ksyms-lds = $(dot-target).lds
457
458quiet_cmd_export_list = EXPORTS $@
459cmd_export_list = $(OBJDUMP) -h $< | \
460 sed -ne '/___ksymtab/s/.*+\([^ ]*\).*/EXTERN(\1)/p' >$(ksyms-lds);\
461 rm -f $(dummy-object);\
462 echo | $(CC) $(a_flags) -c -o $(dummy-object) -x assembler -;\
463 $(LD) $(ld_flags) -r -o $@ -T $(ksyms-lds) $(dummy-object);\
464 rm $(dummy-object) $(ksyms-lds)
465
466$(obj)/lib-ksyms.o: $(lib-target) FORCE
467 $(call if_changed,export_list)
468
469targets += $(obj)/lib-ksyms.o
470
471endif
472
473quiet_cmd_link_multi-m = LD [M] $@
474cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(filter %.o,$^) $(cmd_secanalysis)
475
476$(multi-used-m): FORCE
477 $(call if_changed,link_multi-m)
478 @{ echo $(@:.o=.ko); echo $(filter %.o,$^); \
479 $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
480$(call multi_depend, $(multi-used-m), .o, -objs -y -m)
481
482targets += $(multi-used-m)
483targets := $(filter-out $(PHONY), $(targets))
484
485# Add intermediate targets:
486# When building objects with specific suffix patterns, add intermediate
487# targets that the final targets are derived from.
488intermediate_targets = $(foreach sfx, $(2), \
489 $(patsubst %$(strip $(1)),%$(sfx), \
490 $(filter %$(strip $(1)), $(targets))))
491# %.asn1.o <- %.asn1.[ch] <- %.asn1
492# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
493# %.lex.o <- %.lex.c <- %.l
494# %.tab.o <- %.tab.[ch] <- %.y
495targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
496 $(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
497 $(call intermediate_targets, .lex.o, .lex.c) \
498 $(call intermediate_targets, .tab.o, .tab.c .tab.h)
499
500# Descending
501# ---------------------------------------------------------------------------
502
503PHONY += $(subdir-ym)
504$(subdir-ym):
505 $(Q)$(MAKE) $(build)=$@ need-builtin=$(if $(findstring $@,$(subdir-obj-y)),1)
506
507# Add FORCE to the prequisites of a target to force it to be always rebuilt.
508# ---------------------------------------------------------------------------
509
510PHONY += FORCE
511
512FORCE:
513
514# Read all saved command lines and dependencies for the $(targets) we
515# may be building above, using $(if_changed{,_dep}). As an
516# optimization, we don't need to read them if the target does not
517# exist, we will rebuild anyway in that case.
518
519existing-targets := $(wildcard $(sort $(targets)))
520
521-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
522
523ifneq ($(KBUILD_SRC),)
524# Create directories for object files if they do not exist
525obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets))))
526# If targets exist, their directories apparently exist. Skip mkdir.
527existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
528obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
529ifneq ($(obj-dirs),)
530$(shell mkdir -p $(obj-dirs))
531endif
532endif
533
534# Some files contained in $(targets) are intermediate artifacts.
535# We never want them to be removed automatically.
536.SECONDARY: $(targets)
537
538.PHONY: $(PHONY)