Subject: Re: [PATCH 09/14] kbuild: Only run objtool if there is at least one command

From: Nathan Chancellor <[email-masked]>
Date: Fri, 13 Mar 2026 17:45:22 -0700

On Wed, Mar 04, 2026 at 07:31:28PM -0800, Josh Poimboeuf wrote:
> 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 <[email-masked]>

Reviewed-by: Nathan Chancellor <[email-masked]>
Tested-by: Nathan Chancellor <[email-masked]>

I assume this will go with the rest of the series.

> ---
>  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
>