1# SPDX-License-Identifier: GPL-2.0
2####
3# kbuild: Generic definitions
4
5# Convenient variables
6squote  := '
7empty   :=
8space   := $(empty) $(empty)
9space_escape := _-_SPACE_-_
10pound   := \#
11
12###
13# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
14dot-target = $(@D)/.$(@F)
15
16###
17# dependencies
18depfile = $(dot-target).d
19
20###
21# real prerequisites without phony targets
22real-prereqs = $(filter-out $(PHONY), $^)
23
24###
25# Escape single quote for use in echo statements
26escsq = $(subst $(squote),'\$(squote)',$1)
27
28###
29# Easy method for doing a status message
30       kecho := :
31 quiet_kecho := echo
32silent_kecho := :
33kecho := $($(quiet)kecho)
34
35###
36# filechk is used to check if the content of a generated file is updated.
37# Sample usage:
38#
39# filechk_sample = echo $(KERNELRELEASE)
40# version.h: FORCE
41#	$(call filechk,sample)
42#
43# The rule defined shall write to stdout the content of the new file.
44# The existing file will be compared with the new one.
45# - If no file exist it is created
46# - If the content differ the new file is used
47# - If they are equal no change, and no timestamp update
48define filechk
49	$(Q)set -e;						\
50	mkdir -p $(dir $@);					\
51	trap "rm -f $(dot-target).tmp" EXIT;			\
52	{ $(filechk_$(1)); } > $(dot-target).tmp;		\
53	if [ ! -r $@ ] || ! cmp -s $@ $(dot-target).tmp; then	\
54		$(kecho) '  UPD     $@';			\
55		mv -f $(dot-target).tmp $@;			\
56	fi
57endef
58
59# as-insn: Check whether assembler supports an instruction.
60# Usage: cflags-y += $(call as-insn,CC FLAGS,"insn",option-yes,option-no)
61as-insn = $(if $(shell echo 'void _(void) { asm volatile ( $(2) ); }' \
62                       | $(filter-out -include %/include/xen/config.h,$(1)) \
63                              -c -x c -o /dev/null - 2>&1),$(4),$(3))
64
65# as-option-add: Conditionally add options to flags
66# Usage: $(call as-option-add,CFLAGS,CC,"insn",option-yes,option-no)
67as-option-add = $(eval $(call as-option-add-closure,$(1),$(2),$(3),$(4),$(5)))
68define as-option-add-closure
69    ifeq ($$(call as-insn,$$($(2)) $$($(1)),$$(3),y,n),y)
70        $(1) += $(4)
71    else
72        $(1) += $(5)
73    endif
74endef
75
76# $(call if-success,<command>,<then>,<else>)
77# Return <then> if <command> exits with 0, <else> otherwise.
78if-success = $(shell { $(1); } >/dev/null 2>&1 && echo "$(2)" || echo "$(3)")
79
80# $(call success,<command>)
81# Return y if <command> exits with 0, n otherwise
82success = $(call if-success,$(1),y,n)
83
84# $(call ld-option,<flag>)
85# Return y if the linker supports <flag>, n otherwise
86ld-option = $(call success,$(LD) -v $(1))
87
88# cc-ifversion
89# Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
90cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4))
91
92clang-ifversion = $(shell [ $(CONFIG_CLANG_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4))
93
94###
95# Shorthand for $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.asm-generic obj
96# Usage:
97# $(Q)$(MAKE) $(asm-generic)=dir
98asm-generic := -f $(srctree)/scripts/Makefile.asm-generic obj
99
100###
101# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
102# Usage:
103# $(Q)$(MAKE) $(build)=dir
104build := -f $(srctree)/Rules.mk obj
105
106# Shorthand for $(MAKE) clean
107# Usage:
108# $(Q)$(MAKE) $(clean)=dir
109clean := -f $(srctree)/scripts/Makefile.clean obj
110
111# echo command.
112# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
113echo-cmd = $(if $($(quiet)cmd_$(1)),\
114        echo '  $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
115
116# printing commands
117cmd = @set -e; $(echo-cmd) $(cmd_$(1))
118
119###
120# if_changed      - execute command if any prerequisite is newer than
121#                   target, or command line has changed
122# if_changed_dep  - as if_changed, but uses fixdep to reveal dependencies
123#                   including used config symbols
124# if_changed_rule - as if_changed but execute rule instead
125
126ifneq ($(KBUILD_NOCMDDEP),1)
127# Check if both commands are the same including their order. Result is empty
128# string if equal. User may override this check using make KBUILD_NOCMDDEP=1
129cmd-check = $(filter-out $(subst $(space),$(space_escape),$(strip $(cmd_$@))), \
130                         $(subst $(space),$(space_escape),$(strip $(cmd_$1))))
131else
132cmd-check = $(if $(strip $(cmd_$@)),,1)
133endif
134
135# Replace >$< with >$$< to preserve $ when reloading the .cmd file
136# (needed for make)
137# Replace >#< with >$(pound)< to avoid starting a comment in the .cmd file
138# (needed for make)
139# Replace >'< with >'\''< to be able to enclose the whole string in '...'
140# (needed for the shell)
141make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1)))))
142
143# Find any prerequisites that is newer than target or that does not exist.
144# PHONY targets skipped in both cases.
145any-prereq = $(filter-out $(PHONY),$?)$(filter-out $(PHONY) $(wildcard $^),$^)
146
147# Execute command if command has changed or prerequisite(s) are updated.
148if_changed = $(if $(any-prereq)$(cmd-check),                                 \
149        $(cmd);                                                              \
150        printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
151
152# Execute the command and also postprocess generated .d dependencies file.
153if_changed_dep = $(if $(any-prereq)$(cmd-check),$(cmd_and_fixdep),@:)
154
155cmd_and_fixdep =                                                             \
156        $(cmd);                                                              \
157        tools/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;        \
158        rm -f $(depfile)
159
160# Usage: $(call if_changed_rule,foo)
161# Will check if $(cmd_foo) or any of the prerequisites changed,
162# and if so will execute $(rule_foo).
163if_changed_rule = $(if $(any-prereq)$(cmd-check),$(rule_$(1)),@:)
164
165###
166# why - tell why a target got built
167#       enabled by make V=2
168#       Output (listed in the order they are checked):
169#          (1) - due to target is PHONY
170#          (2) - due to target missing
171#          (3) - due to: file1.h file2.h
172#          (4) - due to command line change
173#          (5) - due to missing .cmd file
174#          (6) - due to target not in $(targets)
175# (1) PHONY targets are always build
176# (2) No target, so we better build it
177# (3) Prerequisite is newer than target
178# (4) The command line stored in the file named dir/.target.cmd
179#     differed from actual command line. This happens when compiler
180#     options changes
181# (5) No dir/.target.cmd file (used to store command line)
182# (6) No dir/.target.cmd file and target not listed in $(targets)
183#     This is a good hint that there is a bug in the kbuild file
184ifeq ($(KBUILD_VERBOSE),2)
185why =                                                                        \
186    $(if $(filter $@, $(PHONY)),- due to target is PHONY,                    \
187        $(if $(wildcard $@),                                                 \
188            $(if $(any-prereq),- due to: $(any-prereq),                      \
189                $(if $(cmd-check),                                           \
190                    $(if $(cmd_$@),- due to command line change,             \
191                        $(if $(filter $@, $(targets)),                       \
192                            - due to missing .cmd file,                      \
193                            - due to $(notdir $@) not in $$(targets)         \
194                         )                                                   \
195                     )                                                       \
196                 )                                                           \
197             ),                                                              \
198             - due to target missing                                         \
199         )                                                                   \
200     )
201
202echo-why = $(call escsq, $(strip $(why)))
203endif
204
205# Useful for describing the dependency of composite objects
206# Usage:
207#   $(call multi-depend, multi-used-targets, suffix-to-remove, suffix-to-add)
208define multi-depend
209$(foreach m, $(notdir $1), \
210	$(eval $(obj)/$(m): \
211	$(addprefix $(obj)/, $(foreach s, $3, $($(m:%$(strip $2)=%$(s)))))))
212endef
213