From: Ard Biesheuvel Date: Tue, 11 Mar 2025 11:06:20 +0000 (+0100) Subject: kbuild: Create intermediate vmlinux build with relocations preserved X-Git-Tag: v6.15-rc1~11^2~15 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ac4f06789b4f;p=thirdparty%2Flinux.git kbuild: Create intermediate vmlinux build with relocations preserved 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given that the vmlinux.relocs input file needed to generate the arch-specific relocation tables may not exist or be out of date, but cannot be constructed using the ordinary Make dependency based rules, because the info needs to be extracted while vmlinux is in its ephemeral,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rules under arch/*/boot can depend on vmlinux.unstripped without running the risk of the data disappearing or being out of date - the final vmlinux generated by the build is not bloated with static relocations that are never needed again after the build completes.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 Signed-off-by: Masahiro Yamada --- diff --git a/.gitignore b/.gitignore index 5937c74d3dc1e..f2f63e47fb886 100644 --- a/.gitignore +++ b/.gitignore @@ -65,6 +65,7 @@ modules.order /vmlinux.32 /vmlinux.map /vmlinux.symvers +/vmlinux.unstripped /vmlinux-gdb.py /vmlinuz /System.map diff --git a/Makefile b/Makefile index 0904b73872cb5..22593a774cf61 100644 --- a/Makefile +++ b/Makefile @@ -1569,7 +1569,7 @@ endif # CONFIG_MODULES # Directories & files removed with 'make clean' CLEAN_FILES += vmlinux.symvers modules-only.symvers \ modules.builtin modules.builtin.modinfo modules.nsdeps \ - modules.builtin.ranges vmlinux.o.map \ + modules.builtin.ranges vmlinux.o.map vmlinux.unstripped \ compile_commands.json rust/test \ rust-project.json .vmlinux.objs .vmlinux.export.c \ .builtin-dtbs-list .builtin-dtb.S diff --git a/arch/mips/Makefile.postlink b/arch/mips/Makefile.postlink index 6cfdc149d3bcd..ea0add7d56b23 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 6b0580949b6a2..0e4cf8ad2f14b 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 b25d524ce5eb4..bfc3d0b75b9b2 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 1ae5478cd6aca..c2b737500a91d 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 8b8a68162c940..445fce66630f5 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 47f56ef719372..d1856a70c9195 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -371,9 +371,6 @@ quiet_cmd_ar = AR $@ quiet_cmd_objcopy = OBJCOPY $@ cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@ -quiet_cmd_strip_relocs = RSTRIP $@ -cmd_strip_relocs = $(OBJCOPY) --remove-section='.rel*' $@ - # Gzip # --------------------------------------------------------------------------- diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index 487f0bf716ad8..b0a6cd5b818c9 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -9,6 +9,20 @@ include $(srctree)/scripts/Makefile.lib targets := +ifdef CONFIG_ARCH_VMLINUX_NEEDS_RELOCS +vmlinux-final := vmlinux.unstripped + +quiet_cmd_strip_relocs = RSTRIP $@ + cmd_strip_relocs = $(OBJCOPY) --remove-section='.rel*' $< $@ + +vmlinux: $(vmlinux-final) FORCE + $(call if_changed,strip_relocs) + +targets += vmlinux +else +vmlinux-final := vmlinux +endif + %.o: %.c FORCE $(call if_changed_rule,cc_o_c) @@ -47,7 +61,7 @@ targets += .builtin-dtbs-list ifdef CONFIG_GENERIC_BUILTIN_DTB targets += .builtin-dtbs.S .builtin-dtbs.o -vmlinux: .builtin-dtbs.o +$(vmlinux-final): .builtin-dtbs.o endif # vmlinux @@ -55,11 +69,11 @@ 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 +86,11 @@ 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 ifdef CONFIG_BUILDTIME_TABLE_SORT @@ -96,7 +110,7 @@ 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