[PATCH 09/14] kbuild: Only run objtool if there is at least one command
From: Josh Poimboeuf
Date: Wed Mar 04 2026 - 22:36:07 EST
Split the objtool args into commands and options, such that if no
commands have been enabled, objtool doesn't run.
This is in preparation in enabling objtool and klp-build for arm64.
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
arch/x86/boot/startup/Makefile | 2 +-
scripts/Makefile.build | 4 +--
scripts/Makefile.lib | 46 ++++++++++++++++++----------------
scripts/Makefile.vmlinux_o | 15 ++++-------
4 files changed, 33 insertions(+), 34 deletions(-)
diff --git a/arch/x86/boot/startup/Makefile b/arch/x86/boot/startup/Makefile
index 5e499cfb29b5..a08297829fc6 100644
--- a/arch/x86/boot/startup/Makefile
+++ b/arch/x86/boot/startup/Makefile
@@ -36,7 +36,7 @@ $(patsubst %.o,$(obj)/%.o,$(lib-y)): OBJECT_FILES_NON_STANDARD := y
# relocations, even if other objtool actions are being deferred.
#
$(pi-objs): objtool-enabled = 1
-$(pi-objs): objtool-args = $(if $(delay-objtool),--dry-run,$(objtool-args-y)) --noabs
+$(pi-objs): objtool-args = $(if $(delay-objtool),--dry-run,$(objtool-cmds-y) $(objtool-opts-y)) --noabs
#
# Confine the startup code by prefixing all symbols with __pi_ (for position
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 32e209bc7985..d2d0776df947 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -277,7 +277,7 @@ endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(target-stem).o)$(OBJECT_FILES_NON_STANDARD)n),$(is-kernel-object))
ifdef CONFIG_OBJTOOL
-$(obj)/%.o: private objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y))
+$(obj)/%.o: private objtool-enabled = $(if $(is-standard-object),$(if $(objtool-cmds-y),$(if $(delay-objtool),$(is-single-obj-m),y)))
endif
ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
@@ -499,7 +499,7 @@ define rule_ld_multi_m
$(call cmd,gen_objtooldep)
endef
-$(multi-obj-m): private objtool-enabled := $(delay-objtool)
+$(multi-obj-m): private objtool-enabled := $(if $(objtool-cmds-y),$(delay-objtool))
$(multi-obj-m): private part-of-module := y
$(multi-obj-m): %.o: %.mod FORCE
$(call if_changed_rule,ld_multi_m)
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 0718e39cedda..40a462581666 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -183,27 +183,31 @@ ifdef CONFIG_OBJTOOL
objtool := $(objtree)/tools/objtool/objtool
-objtool-args-$(CONFIG_HAVE_JUMP_LABEL_HACK) += --hacks=jump_label
-objtool-args-$(CONFIG_HAVE_NOINSTR_HACK) += --hacks=noinstr
-objtool-args-$(CONFIG_MITIGATION_CALL_DEPTH_TRACKING) += --hacks=skylake
-objtool-args-$(CONFIG_X86_KERNEL_IBT) += --ibt
-objtool-args-$(CONFIG_FINEIBT) += --cfi
-objtool-args-$(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL) += --mcount
-ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
-objtool-args-$(CONFIG_HAVE_OBJTOOL_NOP_MCOUNT) += --mnop
-endif
-objtool-args-$(CONFIG_UNWINDER_ORC) += --orc
-objtool-args-$(CONFIG_MITIGATION_RETPOLINE) += --retpoline
-objtool-args-$(CONFIG_MITIGATION_RETHUNK) += --rethunk
-objtool-args-$(CONFIG_MITIGATION_SLS) += --sls
-objtool-args-$(CONFIG_STACK_VALIDATION) += --stackval
-objtool-args-$(CONFIG_HAVE_STATIC_CALL_INLINE) += --static-call
-objtool-args-$(CONFIG_HAVE_UACCESS_VALIDATION) += --uaccess
-objtool-args-$(or $(CONFIG_GCOV_KERNEL),$(CONFIG_KCOV)) += --no-unreachable
-objtool-args-$(CONFIG_PREFIX_SYMBOLS) += --prefix=$(CONFIG_FUNCTION_PADDING_BYTES)
-objtool-args-$(CONFIG_OBJTOOL_WERROR) += --werror
+# objtool commands
+objtool-cmds-$(CONFIG_HAVE_JUMP_LABEL_HACK) += --hacks=jump_label
+objtool-cmds-$(CONFIG_HAVE_NOINSTR_HACK) += --hacks=noinstr
+objtool-cmds-$(CONFIG_MITIGATION_CALL_DEPTH_TRACKING) += --hacks=skylake
+objtool-cmds-$(CONFIG_X86_KERNEL_IBT) += --ibt
+objtool-cmds-$(CONFIG_FINEIBT) += --cfi
+objtool-cmds-$(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL) += --mcount
+objtool-cmds-$(CONFIG_UNWINDER_ORC) += --orc
+objtool-cmds-$(CONFIG_MITIGATION_RETPOLINE) += --retpoline
+objtool-cmds-$(CONFIG_MITIGATION_RETHUNK) += --rethunk
+objtool-cmds-$(CONFIG_MITIGATION_SLS) += --sls
+objtool-cmds-$(CONFIG_STACK_VALIDATION) += --stackval
+objtool-cmds-$(CONFIG_HAVE_STATIC_CALL_INLINE) += --static-call
+objtool-cmds-$(CONFIG_HAVE_UACCESS_VALIDATION) += --uaccess
+objtool-cmds-$(CONFIG_PREFIX_SYMBOLS) += --prefix=$(CONFIG_FUNCTION_PADDING_BYTES)
+objtool-cmds-y += $(OBJTOOL_ARGS)
-objtool-args = $(objtool-args-y) \
+# objtool options
+ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
+objtool-opts-$(CONFIG_HAVE_OBJTOOL_NOP_MCOUNT) += --mnop
+endif
+objtool-opts-$(or $(CONFIG_GCOV_KERNEL),$(CONFIG_KCOV)) += --no-unreachable
+objtool-opts-$(CONFIG_OBJTOOL_WERROR) += --werror
+
+objtool-args = $(objtool-cmds-y) $(objtool-opts-y) \
$(if $(delay-objtool), --link) \
$(if $(part-of-module), --module)
@@ -212,7 +216,7 @@ delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT),$(CONFIG_KLP_
cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool-args) $@)
cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
-objtool-enabled := y
+objtool-enabled = $(if $(objtool-cmds-y),y)
endif # CONFIG_OBJTOOL
diff --git a/scripts/Makefile.vmlinux_o b/scripts/Makefile.vmlinux_o
index 527352c222ff..09af33203bd8 100644
--- a/scripts/Makefile.vmlinux_o
+++ b/scripts/Makefile.vmlinux_o
@@ -36,18 +36,13 @@ endif
# For !delay-objtool + CONFIG_NOINSTR_VALIDATION, it runs on both translation
# units and vmlinux.o, with the latter only used for noinstr/unret validation.
-objtool-enabled := $(or $(delay-objtool),$(CONFIG_NOINSTR_VALIDATION))
-
-ifeq ($(delay-objtool),y)
-vmlinux-objtool-args-y += $(objtool-args-y)
-else
-vmlinux-objtool-args-$(CONFIG_OBJTOOL_WERROR) += --werror
+ifneq ($(delay-objtool),y)
+objtool-cmds-y =
+objtool-opts-y += --link
endif
-vmlinux-objtool-args-$(CONFIG_NOINSTR_VALIDATION) += --noinstr \
- $(if $(or $(CONFIG_MITIGATION_UNRET_ENTRY),$(CONFIG_MITIGATION_SRSO)), --unret)
-
-objtool-args = $(vmlinux-objtool-args-y) --link
+objtool-cmds-$(CONFIG_NOINSTR_VALIDATION) += --noinstr \
+ $(if $(or $(CONFIG_MITIGATION_UNRET_ENTRY),$(CONFIG_MITIGATION_SRSO)), --unret)
# Link of vmlinux.o used for section mismatch analysis
# ---------------------------------------------------------------------------
--
2.53.0