[PATCH] kbuild: Leave objtool binary around with 'make clean'

[Nathan Chancellor]

The difference between 'make clean' and 'make mrproper' is documented in
'make help' as:

  clean     - Remove most generated files but keep the config and
              enough build support to build external modules
  mrproper  - Remove all generated files + config + various backup files

After commit 68b4fe32d737 ("kbuild: Add objtool to top-level clean
target"), running 'make clean' then attempting to build an external
module with the resulting build directory fails with

  $ make ARCH=x86_64 O=build clean

  $ make -C build M=... MO=...
  ...
  /bin/sh: line 1: .../build/tools/objtool/objtool: No such file or directory

as 'make clean' removes the objtool binary.

Split the objtool clean target into mrproper and clean like Kbuild does
and remove all generated artifacts with 'make clean' except for the
objtool binary, which is removed with 'make mrproper'.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 68b4fe32d737 ("kbuild: Add objtool to top-level clean target")
Reported-by: Michal Suchanek <msuchanek@xxxxxxx>
Closes: https://lore.kernel.org/20260225112633.6123-1-msuchanek@xxxxxxx/
Reported-by: Rainer Fiebig <jrf@xxxxxxxxxxx>
Closes: https://lore.kernel.org/62d12399-76e5-3d40-126a-7490b4795b17@xxxxxxxxxxx/
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
---
I realize that this will technically decend into tools/objtool twice
during cleaning when running mrproper but I don't think it is the end of
the world for a much simpler implementation.

I can take this via kbuild-fixes with a proper Ack or it can go through
-tip, does not matter to me.
---
 Makefile               | 8 ++++----
 tools/objtool/Makefile | 6 ++++--
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index e944c6e71e81..d76d706a5580 100644
--- a/Makefile
+++ b/Makefile
@@ -1497,13 +1497,13 @@ ifneq ($(wildcard $(resolve_btfids_O)),)
 	$(Q)$(MAKE) -sC $(srctree)/tools/bpf/resolve_btfids O=$(resolve_btfids_O) clean
 endif
 
-PHONY += objtool_clean
+PHONY += objtool_clean objtool_mrproper
 
 objtool_O = $(abspath $(objtree))/tools/objtool
 
-objtool_clean:
+objtool_clean objtool_mrproper:
 ifneq ($(wildcard $(objtool_O)),)
-	$(Q)$(MAKE) -sC $(abs_srctree)/tools/objtool O=$(objtool_O) srctree=$(abs_srctree) clean
+	$(Q)$(MAKE) -sC $(abs_srctree)/tools/objtool O=$(objtool_O) srctree=$(abs_srctree) $(patsubst objtool_%,%,$@)
 endif
 
 tools/: FORCE
@@ -1686,7 +1686,7 @@ PHONY += $(mrproper-dirs) mrproper
 $(mrproper-dirs):
 	$(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@)
 
-mrproper: clean $(mrproper-dirs)
+mrproper: clean objtool_mrproper $(mrproper-dirs)
 	$(call cmd,rmfiles)
 	@find . $(RCS_FIND_IGNORE) \
 		\( -name '*.rmeta' \) \
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 6964175abdfd..50d3e38e6137 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -142,13 +142,15 @@ $(LIBSUBCMD)-clean:
 	$(Q)$(RM) -r -- $(LIBSUBCMD_OUTPUT)
 
 clean: $(LIBSUBCMD)-clean
-	$(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL)
 	$(Q)find $(OUTPUT) -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
 	$(Q)$(RM) $(OUTPUT)arch/x86/lib/cpu-feature-names.c $(OUTPUT)fixdep
 	$(Q)$(RM) $(OUTPUT)arch/x86/lib/inat-tables.c $(OUTPUT)fixdep
 	$(Q)$(RM) -- $(OUTPUT)FEATURE-DUMP.objtool
 	$(Q)$(RM) -r -- $(OUTPUT)feature
 
+mrproper: clean
+	$(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL)
+
 FORCE:
 
-.PHONY: clean FORCE
+.PHONY: clean mrproper FORCE

---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20260227-avoid-objtool-binary-removal-clean-83ce7fbcc8a1

Best regards,
--  
Nathan Chancellor <nathan@xxxxxxxxxx>