1# SPDX-License-Identifier: GPL-2.0
2####
3# kbuild: Generic definitions
4
5# Convenient variables
6comma   := ,
7quote   := "
8squote  := '
9empty   :=
10space   := $(empty) $(empty)
11space_escape := _-_SPACE_-_
12pound := \#
13
14###
15# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
16dot-target = $(dir $@).$(notdir $@)
17
18###
19# Name of target with a '.tmp_' as filename prefix. foo/bar.o => foo/.tmp_bar.o
20tmp-target = $(dir $@).tmp_$(notdir $@)
21
22###
23# The temporary file to save gcc -MMD generated dependencies must not
24# contain a comma
25depfile = $(subst $(comma),_,$(dot-target).d)
26
27###
28# filename of target with directory and extension stripped
29basetarget = $(basename $(notdir $@))
30
31###
32# real prerequisites without phony targets
33real-prereqs = $(filter-out $(PHONY), $^)
34
35###
36# Escape single quote for use in echo statements
37escsq = $(subst $(squote),'\$(squote)',$1)
38
39###
40# Quote a string to pass it to C files. foo => '"foo"'
41stringify = $(squote)$(quote)$1$(quote)$(squote)
42
43###
44# Easy method for doing a status message
45       kecho := :
46 quiet_kecho := echo
47silent_kecho := :
48kecho := $($(quiet)kecho)
49
50###
51# filechk is used to check if the content of a generated file is updated.
52# Sample usage:
53#
54# filechk_sample = echo $(KERNELRELEASE)
55# version.h: FORCE
56#	$(call filechk,sample)
57#
58# The rule defined shall write to stdout the content of the new file.
59# The existing file will be compared with the new one.
60# - If no file exist it is created
61# - If the content differ the new file is used
62# - If they are equal no change, and no timestamp update
63define filechk
64	$(check-FORCE)
65	$(Q)set -e;						\
66	mkdir -p $(dir $@);					\
67	trap "rm -f $(dot-target).tmp" EXIT;			\
68	{ $(filechk_$(1)); } > $(dot-target).tmp;		\
69	if [ ! -r $@ ] || ! cmp -s $@ $(dot-target).tmp; then	\
70		$(kecho) '  UPD     $@';			\
71		mv -f $(dot-target).tmp $@;			\
72	fi
73endef
74
75###
76# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
77# Usage:
78# $(Q)$(MAKE) $(build)=dir
79build := -f $(srctree)/scripts/Makefile.build obj
80
81###
82# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.dtbinst obj=
83# Usage:
84# $(Q)$(MAKE) $(dtbinst)=dir
85dtbinst := -f $(srctree)/scripts/Makefile.dtbinst obj
86
87###
88# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj=
89# Usage:
90# $(Q)$(MAKE) $(clean)=dir
91clean := -f $(srctree)/scripts/Makefile.clean obj
92
93# echo command.
94# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
95echo-cmd = $(if $($(quiet)cmd_$(1)),\
96	echo '  $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
97
98# sink stdout for 'make -s'
99       redirect :=
100 quiet_redirect :=
101silent_redirect := exec >/dev/null;
102
103# Delete the target on interruption
104#
105# GNU Make automatically deletes the target if it has already been changed by
106# the interrupted recipe. So, you can safely stop the build by Ctrl-C (Make
107# will delete incomplete targets), and resume it later.
108#
109# However, this does not work when the stderr is piped to another program, like
110#  $ make >&2 | tee log
111# Make dies with SIGPIPE before cleaning the targets.
112#
113# To address it, we clean the target in signal traps.
114#
115# Make deletes the target when it catches SIGHUP, SIGINT, SIGQUIT, SIGTERM.
116# So, we cover them, and also SIGPIPE just in case.
117#
118# Of course, this is unneeded for phony targets.
119delete-on-interrupt = \
120	$(if $(filter-out $(PHONY), $@), \
121		$(foreach sig, HUP INT QUIT TERM PIPE, \
122			trap 'rm -f $@; trap - $(sig); kill -s $(sig) $$$$' $(sig);))
123
124# printing commands
125cmd = @set -e; $(echo-cmd) $($(quiet)redirect) $(delete-on-interrupt) $(cmd_$(1))
126
127###
128# if_changed      - execute command if any prerequisite is newer than
129#                   target, or command line has changed
130# if_changed_dep  - as if_changed, but uses fixdep to reveal dependencies
131#                   including used config symbols
132# if_changed_rule - as if_changed but execute rule instead
133# See Documentation/kbuild/makefiles.rst for more info
134
135ifneq ($(KBUILD_NOCMDDEP),1)
136# Check if both commands are the same including their order. Result is empty
137# string if equal. User may override this check using make KBUILD_NOCMDDEP=1
138cmd-check = $(filter-out $(subst $(space),$(space_escape),$(strip $(cmd_$@))), \
139                         $(subst $(space),$(space_escape),$(strip $(cmd_$1))))
140else
141cmd-check = $(if $(strip $(cmd_$@)),,1)
142endif
143
144# Replace >$< with >$$< to preserve $ when reloading the .cmd file
145# (needed for make)
146# Replace >#< with >$(pound)< to avoid starting a comment in the .cmd file
147# (needed for make)
148# Replace >'< with >'\''< to be able to enclose the whole string in '...'
149# (needed for the shell)
150make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1)))))
151
152# Find any prerequisites that are newer than target or that do not exist.
153# (This is not true for now; $? should contain any non-existent prerequisites,
154# but it does not work as expected when .SECONDARY is present. This seems a bug
155# of GNU Make.)
156# PHONY targets skipped in both cases.
157newer-prereqs = $(filter-out $(PHONY),$?)
158
159# It is a typical mistake to forget the FORCE prerequisite. Check it here so
160# no more breakage will slip in.
161check-FORCE = $(if $(filter FORCE, $^),,$(warning FORCE prerequisite is missing))
162
163if-changed-cond = $(newer-prereqs)$(cmd-check)$(check-FORCE)
164
165# Execute command if command has changed or prerequisite(s) are updated.
166if_changed = $(if $(if-changed-cond),$(cmd_and_savecmd),@:)
167
168cmd_and_savecmd =                                                            \
169	$(cmd);                                                              \
170	printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd
171
172# Execute the command and also postprocess generated .d dependencies file.
173if_changed_dep = $(if $(if-changed-cond),$(cmd_and_fixdep),@:)
174
175cmd_and_fixdep =                                                             \
176	$(cmd);                                                              \
177	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;\
178	rm -f $(depfile)
179
180# Usage: $(call if_changed_rule,foo)
181# Will check if $(cmd_foo) or any of the prerequisites changed,
182# and if so will execute $(rule_foo).
183if_changed_rule = $(if $(if-changed-cond),$(rule_$(1)),@:)
184
185###
186# why - tell why a target got built
187#       enabled by make V=2
188#       Output (listed in the order they are checked):
189#          (1) - due to target is PHONY
190#          (2) - due to target missing
191#          (3) - due to: file1.h file2.h
192#          (4) - due to command line change
193#          (5) - due to missing .cmd file
194#          (6) - due to target not in $(targets)
195# (1) PHONY targets are always build
196# (2) No target, so we better build it
197# (3) Prerequisite is newer than target
198# (4) The command line stored in the file named dir/.target.cmd
199#     differed from actual command line. This happens when compiler
200#     options changes
201# (5) No dir/.target.cmd file (used to store command line)
202# (6) No dir/.target.cmd file and target not listed in $(targets)
203#     This is a good hint that there is a bug in the kbuild file
204ifeq ($(KBUILD_VERBOSE),2)
205why =                                                                        \
206    $(if $(filter $@, $(PHONY)),- due to target is PHONY,                    \
207        $(if $(wildcard $@),                                                 \
208            $(if $(newer-prereqs),- due to: $(newer-prereqs),                \
209                $(if $(cmd-check),                                           \
210                    $(if $(cmd_$@),- due to command line change,             \
211                        $(if $(filter $@, $(targets)),                       \
212                            - due to missing .cmd file,                      \
213                            - due to $(notdir $@) not in $$(targets)         \
214                         )                                                   \
215                     )                                                       \
216                 )                                                           \
217             ),                                                              \
218             - due to target missing                                         \
219         )                                                                   \
220     )
221
222echo-why = $(call escsq, $(strip $(why)))
223endif
224
225###############################################################################
226
227# delete partially updated (i.e. corrupted) files on error
228.DELETE_ON_ERROR:
229
230# do not delete intermediate files automatically
231.SECONDARY:
232