arm64: fix vdso-offsets.h dependency
arm64/kernel/{vdso,signal}.c include vdso-offsets.h, as well as any file that includes asm/vdso.h. Therefore, vdso-offsets.h must be generated before these files are compiled. The current rules in arm64/kernel/Makefile do not actually enforce this, because even though $(obj)/vdso is listed as a prerequisite for vdso-offsets.h, this does not result in the intended effect of building the vdso subdirectory (before all the other objects). As a consequence, depending on the order in which the rules are followed, vdso-offsets.h is updated or not before arm64/kernel/{vdso,signal}.o are built. The current rules also impose an unnecessary dependency on vdso-offsets.h for all arm64/kernel/*.o, resulting in unnecessary rebuilds. This is made obvious when using make -j: touch arch/arm64/kernel/vdso/gettimeofday.S && make -j$NCPUS arch/arm64/kernel will sometimes result in none of arm64/kernel/*.o being rebuilt, sometimes all of them, or even just some of them. It is quite difficult to ensure that a header is generated before it is used with recursive Makefiles by using normal rules. Instead, arch-specific generated headers are normally built in the archprepare recipe in the arch Makefile (see for instance arch/ia64/Makefile). Unfortunately, asm-offsets.h is included in gettimeofday.S, and must therefore be generated before vdso-offsets.h, which is not the case if archprepare is used. For this reason, a rule run after archprepare has to be used. This commit adds rules in arm64/Makefile to build vdso-offsets.h during the prepare step, ensuring that vdso-offsets.h is generated before building anything. It also removes the now-unnecessary dependencies on vdso-offsets.h in arm64/kernel/Makefile. Finally, it removes the duplication of asm-offsets.h between arm64/kernel/vdso/ and include/generated/ and makes include/generated/vdso-offsets.h a target in arm64/kernel/vdso/Makefile. Cc: Will Deacon <will.deacon@arm.com> Cc: Michal Marek <mmarek@suse.com> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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@ -121,6 +121,16 @@ archclean:
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$(Q)$(MAKE) $(clean)=$(boot)
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$(Q)$(MAKE) $(clean)=$(boot)/dts
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# We need to generate vdso-offsets.h before compiling certain files in kernel/.
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# In order to do that, we should use the archprepare target, but we can't since
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# asm-offsets.h is included in some files used to generate vdso-offsets.h, and
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# asm-offsets.h is built in prepare0, for which archprepare is a dependency.
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# Therefore we need to generate the header after prepare0 has been made, hence
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# this hack.
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prepare: vdso_prepare
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vdso_prepare: prepare0
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$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso include/generated/vdso-offsets.h
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define archhelp
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echo '* Image.gz - Compressed kernel image (arch/$(ARCH)/boot/Image.gz)'
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echo ' Image - Uncompressed kernel image (arch/$(ARCH)/boot/Image)'
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@ -53,7 +53,3 @@ obj-y += $(arm64-obj-y) vdso/
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obj-m += $(arm64-obj-m)
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head-y := head.o
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extra-y += $(head-y) vmlinux.lds
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# vDSO - this must be built first to generate the symbol offsets
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$(call objectify,$(arm64-obj-y)): $(obj)/vdso/vdso-offsets.h
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$(obj)/vdso/vdso-offsets.h: $(obj)/vdso
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@ -23,7 +23,7 @@ GCOV_PROFILE := n
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ccflags-y += -Wl,-shared
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obj-y += vdso.o
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extra-y += vdso.lds vdso-offsets.h
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extra-y += vdso.lds
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CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
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# Force dependency (incbin is bad)
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@ -42,11 +42,10 @@ $(obj)/%.so: $(obj)/%.so.dbg FORCE
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gen-vdsosym := $(srctree)/$(src)/gen_vdso_offsets.sh
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quiet_cmd_vdsosym = VDSOSYM $@
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define cmd_vdsosym
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$(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@ && \
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cp $@ include/generated/
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$(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@
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endef
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$(obj)/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE
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include/generated/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE
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$(call if_changed,vdsosym)
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# Assembly rules for the .S files
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