On Mon, Feb 24, 2025 at 10:22 PM Ard Biesheuvel <ardb+git@xxxxxxxxxx> wrote: > > From: Ard Biesheuvel <ardb@xxxxxxxxxx> > > The imperative paradigm used to build vmlinux, extract some info from it > or perform some checks on it, and subsequently modify it again goes > against the declarative paradigm that is usually employed for defining > make rules. > > In particular, the Makefile.postlink files that consume their input via > an output rule result in some dodgy logic in the decompressor makefiles > for RISC-V and x86, given that the vmlinux.relocs input file needed to > generate the arch-specific relocation tables may not exist or be out of > date, but cannot be constructed using the ordinary Make dependency based > rules, because the info needs to be extracted while vmlinux is in its > ephemeral, non-stripped form. > > So instead, for architectures that require the static relocations that > are emitted into vmlinux when passing --emit-relocs to the linker, and > are subsequently stripped out again, introduce an intermediate vmlinux > target called vmlinux.unstripped, and organize the reset of the build > logic accordingly: > > - vmlinux.unstripped is created only once, and not updated again > - build rules under arch/*/boot can depend on vmlinux.unstripped without > running the risk of the data disappearing or being out of date > - the final vmlinux generated by the build is not bloated with static > relocations that are never needed again after the build completes. > > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > --- I already expressed my concern in the cover-letter. Other than that, there are some nits: - You need to update .gitignore to ignore vmlinux.unstripped and the 'clean' target to clean up vmlinux.unstripped. - cmd_strip_relocs can be moved to scripts/Makefile.vmlinux from scripts/Makefile.lib > arch/mips/Makefile.postlink | 2 +- > arch/riscv/Makefile.postlink | 11 +-------- > arch/riscv/boot/Makefile | 5 +--- > arch/s390/Makefile.postlink | 4 +--- > arch/x86/Makefile.postlink | 8 +++---- > scripts/Makefile.lib | 2 +- > scripts/Makefile.vmlinux | 25 ++++++++++++++------ > 7 files changed, 26 insertions(+), 31 deletions(-) > > diff --git a/arch/mips/Makefile.postlink b/arch/mips/Makefile.postlink > index 6cfdc149d3bc..ea0add7d56b2 100644 > --- a/arch/mips/Makefile.postlink > +++ b/arch/mips/Makefile.postlink > @@ -22,7 +22,7 @@ quiet_cmd_relocs = RELOCS $@ > > # `@true` prevents complaint when there is nothing to be done > > -vmlinux: FORCE > +vmlinux vmlinux.unstripped: FORCE > @true > ifeq ($(CONFIG_CPU_LOONGSON3_WORKAROUNDS),y) > $(call if_changed,ls3_llsc) > diff --git a/arch/riscv/Makefile.postlink b/arch/riscv/Makefile.postlink > index 6b0580949b6a..0e4cf8ad2f14 100644 > --- a/arch/riscv/Makefile.postlink > +++ b/arch/riscv/Makefile.postlink > @@ -10,26 +10,17 @@ __archpost: > > -include include/config/auto.conf > include $(srctree)/scripts/Kbuild.include > -include $(srctree)/scripts/Makefile.lib > > quiet_cmd_relocs_check = CHKREL $@ > cmd_relocs_check = \ > $(CONFIG_SHELL) $(srctree)/arch/riscv/tools/relocs_check.sh "$(OBJDUMP)" "$(NM)" "$@" > > -ifdef CONFIG_RELOCATABLE > -quiet_cmd_cp_vmlinux_relocs = CPREL vmlinux.relocs > -cmd_cp_vmlinux_relocs = cp vmlinux vmlinux.relocs > - > -endif > - > # `@true` prevents complaint when there is nothing to be done > > -vmlinux: FORCE > +vmlinux vmlinux.unstripped: FORCE > @true > ifdef CONFIG_RELOCATABLE > $(call if_changed,relocs_check) > - $(call if_changed,cp_vmlinux_relocs) > - $(call if_changed,strip_relocs) > endif > > clean: > diff --git a/arch/riscv/boot/Makefile b/arch/riscv/boot/Makefile > index b25d524ce5eb..bfc3d0b75b9b 100644 > --- a/arch/riscv/boot/Makefile > +++ b/arch/riscv/boot/Makefile > @@ -32,10 +32,7 @@ $(obj)/xipImage: vmlinux FORCE > endif > > ifdef CONFIG_RELOCATABLE > -vmlinux.relocs: vmlinux > - @ (! [ -f vmlinux.relocs ] && echo "vmlinux.relocs can't be found, please remove vmlinux and try again") || true > - > -$(obj)/Image: vmlinux.relocs FORCE > +$(obj)/Image: vmlinux.unstripped FORCE > else > $(obj)/Image: vmlinux FORCE > endif > diff --git a/arch/s390/Makefile.postlink b/arch/s390/Makefile.postlink > index 1ae5478cd6ac..c2b737500a91 100644 > --- a/arch/s390/Makefile.postlink > +++ b/arch/s390/Makefile.postlink > @@ -11,7 +11,6 @@ __archpost: > > -include include/config/auto.conf > include $(srctree)/scripts/Kbuild.include > -include $(srctree)/scripts/Makefile.lib > > CMD_RELOCS=arch/s390/tools/relocs > OUT_RELOCS = arch/s390/boot > @@ -20,9 +19,8 @@ quiet_cmd_relocs = RELOCS $(OUT_RELOCS)/relocs.S > mkdir -p $(OUT_RELOCS); \ > $(CMD_RELOCS) $@ > $(OUT_RELOCS)/relocs.S > > -vmlinux: FORCE > +vmlinux.unstripped: FORCE > $(call cmd,relocs) > - $(call cmd,strip_relocs) > > clean: > @rm -f $(OUT_RELOCS)/relocs.S > diff --git a/arch/x86/Makefile.postlink b/arch/x86/Makefile.postlink > index 8b8a68162c94..445fce66630f 100644 > --- a/arch/x86/Makefile.postlink > +++ b/arch/x86/Makefile.postlink > @@ -11,23 +11,21 @@ __archpost: > > -include include/config/auto.conf > include $(srctree)/scripts/Kbuild.include > -include $(srctree)/scripts/Makefile.lib > > CMD_RELOCS = arch/x86/tools/relocs > OUT_RELOCS = arch/x86/boot/compressed > -quiet_cmd_relocs = RELOCS $(OUT_RELOCS)/$@.relocs > +quiet_cmd_relocs = RELOCS $(OUT_RELOCS)/vmlinux.relocs > cmd_relocs = \ > mkdir -p $(OUT_RELOCS); \ > - $(CMD_RELOCS) $@ > $(OUT_RELOCS)/$@.relocs; \ > + $(CMD_RELOCS) $@ > $(OUT_RELOCS)/vmlinux.relocs; \ > $(CMD_RELOCS) --abs-relocs $@ > > # `@true` prevents complaint when there is nothing to be done > > -vmlinux: FORCE > +vmlinux vmlinux.unstripped: FORCE > @true > ifeq ($(CONFIG_X86_NEED_RELOCS),y) > $(call cmd,relocs) > - $(call cmd,strip_relocs) > endif > > clean: > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib > index cad20f0e66ee..7a023f17a21d 100644 > --- a/scripts/Makefile.lib > +++ b/scripts/Makefile.lib > @@ -377,7 +377,7 @@ quiet_cmd_objcopy = OBJCOPY $@ > cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@ > > quiet_cmd_strip_relocs = RSTRIP $@ > -cmd_strip_relocs = $(OBJCOPY) --remove-section='.rel*' $@ > +cmd_strip_relocs = $(OBJCOPY) --remove-section='.rel*' $< $@ > > # Gzip > # --------------------------------------------------------------------------- > diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux > index 3523ce3ce3dc..1e3ea8e4b4b0 100644 > --- a/scripts/Makefile.vmlinux > +++ b/scripts/Makefile.vmlinux > @@ -9,6 +9,17 @@ include $(srctree)/scripts/Makefile.lib > > targets := > > +ifdef CONFIG_ARCH_VMLINUX_NEEDS_RELOCS > +vmlinux-final := vmlinux.unstripped > + > +vmlinux: $(vmlinux-final) FORCE > + $(call if_changed,strip_relocs) > + > +targets += vmlinux > +else > +vmlinux-final := vmlinux > +endif > + > %.o: %.c FORCE > $(call if_changed_rule,cc_o_c) > > @@ -47,7 +58,7 @@ targets += .builtin-dtbs-list > > ifdef CONFIG_GENERIC_BUILTIN_DTB > targets += .builtin-dtbs.S .builtin-dtbs.o > -vmlinux: .builtin-dtbs.o > +$(vmlinux-final): .builtin-dtbs.o > endif > > # vmlinux > @@ -55,11 +66,11 @@ endif > > ifdef CONFIG_MODULES > targets += .vmlinux.export.o > -vmlinux: .vmlinux.export.o > +$(vmlinux-final): .vmlinux.export.o > endif > > ifdef CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX > -vmlinux: arch/$(SRCARCH)/tools/vmlinux.arch.o > +$(vmlinux-final): arch/$(SRCARCH)/tools/vmlinux.arch.o > > arch/$(SRCARCH)/tools/vmlinux.arch.o: vmlinux.o FORCE > $(Q)$(MAKE) $(build)=arch/$(SRCARCH)/tools $@ > @@ -72,11 +83,11 @@ cmd_link_vmlinux = \ > $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)" "$@"; \ > $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true) > > -targets += vmlinux > -vmlinux: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE > +targets += $(vmlinux-final) > +$(vmlinux-final): scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE > +$(call if_changed_dep,link_vmlinux) > ifdef CONFIG_DEBUG_INFO_BTF > -vmlinux: $(RESOLVE_BTFIDS) > +$(vmlinux-final): $(RESOLVE_BTFIDS) > endif > > # module.builtin.ranges > @@ -92,7 +103,7 @@ modules.builtin.ranges: $(srctree)/scripts/generate_builtin_ranges.awk \ > modules.builtin vmlinux.map vmlinux.o.map FORCE > $(call if_changed,modules_builtin_ranges) > > -vmlinux.map: vmlinux > +vmlinux.map: $(vmlinux-final) > @: > > endif > -- > 2.48.1.601.g30ceb7b040-goog > > -- Best Regards Masahiro Yamada
