[PATCH v3 09/21] kbuild: Only run objtool if there is at least one command

[Josh Poimboeuf <jpoimboe@kernel.org>]

Split the objtool args into commands and options, such that if no
commands have been enabled, objtool doesn't run.

This is in preparation for enabling objtool and klp-build for arm64.

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/x86/boot/startup/Makefile |  2 +-
 scripts/Makefile.build         |  4 +--
 scripts/Makefile.lib           | 52 ++++++++++++++++++----------------
 scripts/Makefile.vmlinux_o     | 15 ++++------
 4 files changed, 36 insertions(+), 37 deletions(-)

diff --git a/arch/x86/boot/startup/Makefile b/arch/x86/boot/startup/Makefile
index 5e499cfb29b5c..a08297829fc63 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 3498d25b15e85..c4accfcd177d4 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 = $(and $(is-standard-object),$(objtool-cmds-y),$(if $(delay-objtool),$(is-single-obj-m),y))
 endif
 
 ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
@@ -501,7 +501,7 @@ 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 7e216d82e9887..7f803796d20cf 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -183,30 +183,34 @@ 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-$(CONFIG_CALL_PADDING)			+= --prefix=$(CONFIG_FUNCTION_PADDING_BYTES)
-ifdef CONFIG_CALL_PADDING
-objtool-args-$(CONFIG_CFI)				+= --cfi
-objtool-args-$(CONFIG_FINEIBT)				+= --fineibt
-endif
-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-$(CONFIG_OBJTOOL_WERROR)			+= --werror
+# objtool commands
+objtool-cmds-$(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_CALL_PADDING)			+= --prefix=$(CONFIG_FUNCTION_PADDING_BYTES)
+objtool-cmds-$(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-y						+= $(OBJTOOL_ARGS)
 
-objtool-args = $(objtool-args-y)					\
+# objtool options
+ifdef CONFIG_CALL_PADDING
+objtool-opts-$(CONFIG_CFI)				+= --cfi
+objtool-opts-$(CONFIG_FINEIBT)				+= --fineibt
+endif
+ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
+objtool-opts-$(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)
 
@@ -215,7 +219,7 @@ 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 527352c222ff6..09af33203bd8d 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