00791e017b
[ Upstream commit a7f3257da8a86b96fb9bf1bba40ae0bbd7f1885a ]
When receiving some signal, GNU Make automatically deletes the target if
it has already been changed by the interrupted recipe.
If the target is possibly incomplete due to interruption, it must be
deleted so that it will be remade from scratch on the next run of make.
Otherwise, the target would remain corrupted permanently because its
timestamp had already been updated.
Thanks to this behavior of Make, you can stop the build any time by
pressing Ctrl-C, and just run 'make' to resume it.
Kbuild also relies on this feature, but it is equivalently important
for any build systems that make decisions based on timestamps (if you
want to support Ctrl-C reliably).
However, this does not always work as claimed; Make immediately dies
with Ctrl-C if its stderr goes into a pipe.
[Test Makefile]
foo:
echo hello > $@
sleep 3
echo world >> $@
[Test Result]
$ make # hit Ctrl-C
echo hello > foo
sleep 3
^Cmake: *** Deleting file 'foo'
make: *** [Makefile:3: foo] Interrupt
$ make 2>&1 | cat # hit Ctrl-C
echo hello > foo
sleep 3
^C$ # 'foo' is often left-over
The reason is because SIGINT is sent to the entire process group.
In this example, SIGINT kills 'cat', and 'make' writes the message to
the closed pipe, then dies with SIGPIPE before cleaning the target.
A typical bad scenario (as reported by [1], [2]) is to save build log
by using the 'tee' command:
$ make 2>&1 | tee log
This can be problematic for any build systems based on Make, so I hope
it will be fixed in GNU Make. The maintainer of GNU Make stated this is
a long-standing issue and difficult to fix [3]. It has not been fixed
yet as of writing.
So, we cannot rely on Make cleaning the target. We can do it by
ourselves, in signal traps.
As far as I understand, Make takes care of SIGHUP, SIGINT, SIGQUIT, and
SITERM for the target removal. I added the traps for them, and also for
SIGPIPE just in case cmd_* rule prints something to stdout or stderr
(but I did not observe an actual case where SIGPIPE was triggered).
[Note 1]
The trap handler might be worth explaining.
rm -f $@; trap - $(sig); kill -s $(sig) $$
This lets the shell kill itself by the signal it caught, so the parent
process can tell the child has exited on the signal. Generally, this is
a proper manner for handling signals, in case the calling program (like
Bash) may monitor WIFSIGNALED() and WTERMSIG() for WCE although this may
not be a big deal here because GNU Make handles SIGHUP, SIGINT, SIGQUIT
in WUE and SIGTERM in IUE.
IUE - Immediate Unconditional Exit
WUE - Wait and Unconditional Exit
WCE - Wait and Cooperative Exit
For details, see "Proper handling of SIGINT/SIGQUIT" [4].
[Note 2]
Reverting 392885ee82 ("kbuild: let fixdep directly write to .*.cmd
files") would directly address [1], but it only saves if_changed_dep.
As reported in [2], all commands that use redirection can potentially
leave an empty (i.e. broken) target.
[Note 3]
Another (even safer) approach might be to always write to a temporary
file, and rename it to $@ at the end of the recipe.
<command> > $(tmp-target)
mv $(tmp-target) $@
It would require a lot of Makefile changes, and result in ugly code,
so I did not take it.
[Note 4]
A little more thoughts about a pattern rule with multiple targets (or
a grouped target).
%.x %.y: %.z
<recipe>
When interrupted, GNU Make deletes both %.x and %.y, while this solution
only deletes $@. Probably, this is not a big deal. The next run of make
will execute the rule again to create $@ along with the other files.
[1]: https://lore.kernel.org/all/YLeot94yAaM4xbMY@gmail.com/
[2]: https://lore.kernel.org/all/20220510221333.2770571-1-robh@kernel.org/
[3]: https://lists.gnu.org/archive/html/help-make/2021-06/msg00001.html
[4]: https://www.cons.org/cracauer/sigint.html
Fixes: 392885ee82 ("kbuild: let fixdep directly write to .*.cmd files")
Reported-by: Ingo Molnar <mingo@kernel.org>
Reported-by: Rob Herring <robh@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
355 lines
13 KiB
Plaintext
355 lines
13 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0
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####
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# kbuild: Generic definitions
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# Convenient variables
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comma := ,
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quote := "
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squote := '
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empty :=
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space := $(empty) $(empty)
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space_escape := _-_SPACE_-_
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pound := \#
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###
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# Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
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dot-target = $(dir $@).$(notdir $@)
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###
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# The temporary file to save gcc -MD generated dependencies must not
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# contain a comma
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depfile = $(subst $(comma),_,$(dot-target).d)
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###
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# filename of target with directory and extension stripped
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basetarget = $(basename $(notdir $@))
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###
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# real prerequisites without phony targets
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real-prereqs = $(filter-out $(PHONY), $^)
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###
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# Escape single quote for use in echo statements
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escsq = $(subst $(squote),'\$(squote)',$1)
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###
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# Easy method for doing a status message
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kecho := :
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quiet_kecho := echo
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silent_kecho := :
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kecho := $($(quiet)kecho)
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###
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# filechk is used to check if the content of a generated file is updated.
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# Sample usage:
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#
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# filechk_sample = echo $(KERNELRELEASE)
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# version.h: FORCE
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# $(call filechk,sample)
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#
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# The rule defined shall write to stdout the content of the new file.
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# The existing file will be compared with the new one.
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# - If no file exist it is created
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# - If the content differ the new file is used
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# - If they are equal no change, and no timestamp update
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# - stdin is piped in from the first prerequisite ($<) so one has
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# to specify a valid file as first prerequisite (often the kbuild file)
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define filechk
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$(Q)set -e; \
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mkdir -p $(dir $@); \
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trap "rm -f $(dot-target).tmp" EXIT; \
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{ $(filechk_$(1)); } > $(dot-target).tmp; \
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if [ ! -r $@ ] || ! cmp -s $@ $(dot-target).tmp; then \
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$(kecho) ' UPD $@'; \
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mv -f $(dot-target).tmp $@; \
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fi
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endef
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######
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# gcc support functions
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# See documentation in Documentation/kbuild/makefiles.rst
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# cc-cross-prefix
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# Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
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# Return first <prefix> where a <prefix>gcc is found in PATH.
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# If no gcc found in PATH with listed prefixes return nothing
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#
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# Note: '2>/dev/null' is here to force Make to invoke a shell. Otherwise, it
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# would try to directly execute the shell builtin 'command'. This workaround
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# should be kept for a long time since this issue was fixed only after the
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# GNU Make 4.2.1 release.
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cc-cross-prefix = $(firstword $(foreach c, $(1), \
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$(if $(shell command -v -- $(c)gcc 2>/dev/null), $(c))))
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# output directory for tests below
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TMPOUT = $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_$$$$
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# try-run
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# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise)
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# Exit code chooses option. "$$TMP" serves as a temporary file and is
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# automatically cleaned up.
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try-run = $(shell set -e; \
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TMP=$(TMPOUT)/tmp; \
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TMPO=$(TMPOUT)/tmp.o; \
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mkdir -p $(TMPOUT); \
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trap "rm -rf $(TMPOUT)" EXIT; \
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if ($(1)) >/dev/null 2>&1; \
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then echo "$(2)"; \
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else echo "$(3)"; \
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fi)
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# as-option
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# Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,)
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as-option = $(call try-run,\
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$(CC) $(KBUILD_CFLAGS) $(1) -c -x assembler /dev/null -o "$$TMP",$(1),$(2))
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# as-instr
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# Usage: cflags-y += $(call as-instr,instr,option1,option2)
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as-instr = $(call try-run,\
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printf "%b\n" "$(1)" | $(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3))
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# __cc-option
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# Usage: MY_CFLAGS += $(call __cc-option,$(CC),$(MY_CFLAGS),-march=winchip-c6,-march=i586)
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__cc-option = $(call try-run,\
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$(1) -Werror $(2) $(3) -c -x c /dev/null -o "$$TMP",$(3),$(4))
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# Do not attempt to build with gcc plugins during cc-option tests.
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# (And this uses delayed resolution so the flags will be up to date.)
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CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
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# cc-option
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# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
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cc-option = $(call __cc-option, $(CC),\
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$(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2))
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# cc-option-yn
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# Usage: flag := $(call cc-option-yn,-march=winchip-c6)
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cc-option-yn = $(call try-run,\
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$(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
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# cc-disable-warning
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# Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
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cc-disable-warning = $(call try-run,\
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$(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
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# cc-ifversion
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# Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
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cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4))
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# ld-option
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# Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y)
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ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))
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# ld-version
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# Note this is mainly for HJ Lu's 3 number binutil versions
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ld-version = $(shell $(LD) --version | $(srctree)/scripts/ld-version.sh)
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# ld-ifversion
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# Usage: $(call ld-ifversion, -ge, 22252, y)
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ld-ifversion = $(shell [ $(ld-version) $(1) $(2) ] && echo $(3) || echo $(4))
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######
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###
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# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
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# Usage:
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# $(Q)$(MAKE) $(build)=dir
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build := -f $(srctree)/scripts/Makefile.build obj
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###
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# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.modbuiltin obj=
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# Usage:
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# $(Q)$(MAKE) $(modbuiltin)=dir
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modbuiltin := -f $(srctree)/scripts/Makefile.modbuiltin obj
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###
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# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.dtbinst obj=
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# Usage:
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# $(Q)$(MAKE) $(dtbinst)=dir
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dtbinst := -f $(srctree)/scripts/Makefile.dtbinst obj
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###
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# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj=
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# Usage:
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# $(Q)$(MAKE) $(clean)=dir
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clean := -f $(srctree)/scripts/Makefile.clean obj
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# echo command.
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# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
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echo-cmd = $(if $($(quiet)cmd_$(1)),\
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echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
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# sink stdout for 'make -s'
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redirect :=
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quiet_redirect :=
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silent_redirect := exec >/dev/null;
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# Delete the target on interruption
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#
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# GNU Make automatically deletes the target if it has already been changed by
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# the interrupted recipe. So, you can safely stop the build by Ctrl-C (Make
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# will delete incomplete targets), and resume it later.
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#
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# However, this does not work when the stderr is piped to another program, like
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# $ make >&2 | tee log
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# Make dies with SIGPIPE before cleaning the targets.
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#
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# To address it, we clean the target in signal traps.
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#
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# Make deletes the target when it catches SIGHUP, SIGINT, SIGQUIT, SIGTERM.
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# So, we cover them, and also SIGPIPE just in case.
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#
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# Of course, this is unneeded for phony targets.
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delete-on-interrupt = \
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$(if $(filter-out $(PHONY), $@), \
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$(foreach sig, HUP INT QUIT TERM PIPE, \
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trap 'rm -f $@; trap - $(sig); kill -s $(sig) $$$$' $(sig);))
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# printing commands
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cmd = @set -e; $(echo-cmd) $($(quiet)redirect) $(delete-on-interrupt) $(cmd_$(1))
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###
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# if_changed - execute command if any prerequisite is newer than
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# target, or command line has changed
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# if_changed_dep - as if_changed, but uses fixdep to reveal dependencies
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# including used config symbols
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# if_changed_rule - as if_changed but execute rule instead
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# See Documentation/kbuild/makefiles.rst for more info
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ifneq ($(KBUILD_NOCMDDEP),1)
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# Check if both commands are the same including their order. Result is empty
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# string if equal. User may override this check using make KBUILD_NOCMDDEP=1
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cmd-check = $(filter-out $(subst $(space),$(space_escape),$(strip $(cmd_$@))), \
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$(subst $(space),$(space_escape),$(strip $(cmd_$1))))
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else
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cmd-check = $(if $(strip $(cmd_$@)),,1)
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endif
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# Replace >$< with >$$< to preserve $ when reloading the .cmd file
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# (needed for make)
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# Replace >#< with >$(pound)< to avoid starting a comment in the .cmd file
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# (needed for make)
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# Replace >'< with >'\''< to be able to enclose the whole string in '...'
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# (needed for the shell)
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make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1)))))
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# Find any prerequisites that is newer than target or that does not exist.
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# PHONY targets skipped in both cases.
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any-prereq = $(filter-out $(PHONY),$?)$(filter-out $(PHONY) $(wildcard $^),$^)
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# Execute command if command has changed or prerequisite(s) are updated.
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if_changed = $(if $(any-prereq)$(cmd-check), \
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$(cmd); \
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printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
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# Execute the command and also postprocess generated .d dependencies file.
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if_changed_dep = $(if $(any-prereq)$(cmd-check),$(cmd_and_fixdep),@:)
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cmd_and_fixdep = \
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$(cmd); \
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scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;\
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rm -f $(depfile)
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# Usage: $(call if_changed_rule,foo)
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# Will check if $(cmd_foo) or any of the prerequisites changed,
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# and if so will execute $(rule_foo).
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if_changed_rule = $(if $(any-prereq)$(cmd-check),$(rule_$(1)),@:)
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###
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# why - tell why a target got built
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# enabled by make V=2
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# Output (listed in the order they are checked):
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# (1) - due to target is PHONY
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# (2) - due to target missing
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# (3) - due to: file1.h file2.h
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# (4) - due to command line change
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# (5) - due to missing .cmd file
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# (6) - due to target not in $(targets)
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# (1) PHONY targets are always build
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# (2) No target, so we better build it
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# (3) Prerequisite is newer than target
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# (4) The command line stored in the file named dir/.target.cmd
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# differed from actual command line. This happens when compiler
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# options changes
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# (5) No dir/.target.cmd file (used to store command line)
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# (6) No dir/.target.cmd file and target not listed in $(targets)
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# This is a good hint that there is a bug in the kbuild file
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ifeq ($(KBUILD_VERBOSE),2)
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why = \
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$(if $(filter $@, $(PHONY)),- due to target is PHONY, \
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$(if $(wildcard $@), \
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$(if $(any-prereq),- due to: $(any-prereq), \
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$(if $(cmd-check), \
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$(if $(cmd_$@),- due to command line change, \
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$(if $(filter $@, $(targets)), \
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- due to missing .cmd file, \
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- due to $(notdir $@) not in $$(targets) \
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) \
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) \
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) \
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), \
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- due to target missing \
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) \
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)
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echo-why = $(call escsq, $(strip $(why)))
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endif
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###############################################################################
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#
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# When a Kconfig string contains a filename, it is suitable for
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# passing to shell commands. It is surrounded by double-quotes, and
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# any double-quotes or backslashes within it are escaped by
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# backslashes.
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#
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# This is no use for dependencies or $(wildcard). We need to strip the
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# surrounding quotes and the escaping from quotes and backslashes, and
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# we *do* need to escape any spaces in the string. So, for example:
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#
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# Usage: $(eval $(call config_filename,FOO))
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#
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# Defines FOO_FILENAME based on the contents of the CONFIG_FOO option,
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# transformed as described above to be suitable for use within the
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# makefile.
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#
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# Also, if the filename is a relative filename and exists in the source
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# tree but not the build tree, define FOO_SRCPREFIX as $(srctree)/ to
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# be prefixed to *both* command invocation and dependencies.
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#
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# Note: We also print the filenames in the quiet_cmd_foo text, and
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# perhaps ought to have a version specially escaped for that purpose.
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# But it's only cosmetic, and $(patsubst "%",%,$(CONFIG_FOO)) is good
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# enough. It'll strip the quotes in the common case where there's no
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# space and it's a simple filename, and it'll retain the quotes when
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# there's a space. There are some esoteric cases in which it'll print
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# the wrong thing, but we don't really care. The actual dependencies
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# and commands *do* get it right, with various combinations of single
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# and double quotes, backslashes and spaces in the filenames.
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#
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###############################################################################
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#
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define config_filename
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ifneq ($$(CONFIG_$(1)),"")
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$(1)_FILENAME := $$(subst \\,\,$$(subst \$$(quote),$$(quote),$$(subst $$(space_escape),\$$(space),$$(patsubst "%",%,$$(subst $$(space),$$(space_escape),$$(CONFIG_$(1)))))))
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ifneq ($$(patsubst /%,%,$$(firstword $$($(1)_FILENAME))),$$(firstword $$($(1)_FILENAME)))
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else
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ifeq ($$(wildcard $$($(1)_FILENAME)),)
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ifneq ($$(wildcard $$(srctree)/$$($(1)_FILENAME)),)
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$(1)_SRCPREFIX := $(srctree)/
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endif
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endif
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endif
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endif
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endef
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#
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###############################################################################
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# delete partially updated (i.e. corrupted) files on error
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.DELETE_ON_ERROR:
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# do not delete intermediate files automatically
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.SECONDARY:
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