kbuild: use objtool-args-y to clean up objtool arguments

Based on Linus' patch. Refactor scripts/Makefile.vmlinux_o as well.

Link: https://lore.kernel.org/lkml/CAHk-=wgjTMQgiKzBZTmb=uWGDEQxDdyF1+qxBkODYciuNsmwnw@mail.gmail.com/
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

scripts/Makefile.lib

@@ -229,25 +229,26 @@ ifdef CONFIG_OBJTOOL
 
 objtool := $(objtree)/tools/objtool/objtool
 
-objtool_args =								\
-	$(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label)	\
-	$(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr)		\
-	$(if $(CONFIG_X86_KERNEL_IBT), --ibt)				\
-	$(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount)		\
-	$(if $(CONFIG_UNWINDER_ORC), --orc)				\
-	$(if $(CONFIG_RETPOLINE), --retpoline)				\
-	$(if $(CONFIG_RETHUNK), --rethunk)				\
-	$(if $(CONFIG_SLS), --sls)					\
-	$(if $(CONFIG_STACK_VALIDATION), --stackval)			\
-	$(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call)		\
-	$(if $(CONFIG_HAVE_UACCESS_VALIDATION), --uaccess)		\
+objtool-args-$(CONFIG_HAVE_JUMP_LABEL_HACK)		+= --hacks=jump_label
+objtool-args-$(CONFIG_HAVE_NOINSTR_HACK)		+= --hacks=noinstr
+objtool-args-$(CONFIG_X86_KERNEL_IBT)			+= --ibt
+objtool-args-$(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL)	+= --mcount
+objtool-args-$(CONFIG_UNWINDER_ORC)			+= --orc
+objtool-args-$(CONFIG_RETPOLINE)			+= --retpoline
+objtool-args-$(CONFIG_RETHUNK)				+= --rethunk
+objtool-args-$(CONFIG_SLS)				+= --sls
+objtool-args-$(CONFIG_STACK_VALIDATION)			+= --stackval
+objtool-args-$(CONFIG_HAVE_STATIC_CALL_INLINE)		+= --static-call
+objtool-args-$(CONFIG_HAVE_UACCESS_VALIDATION)		+= --uaccess
+objtool-args-$(CONFIG_GCOV_KERNEL)			+= --no-unreachable
+
+objtool-args = $(objtool-args-y)					\
 	$(if $(delay-objtool), --link)					\
-	$(if $(part-of-module), --module)				\
-	$(if $(CONFIG_GCOV_KERNEL), --no-unreachable)
+	$(if $(part-of-module), --module)
 
 delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT))
 
-cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
+cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool-args) $@)
 cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
 
 endif # CONFIG_OBJTOOL

scripts/Makefile.vmlinux_o

@@ -35,18 +35,11 @@ endif
 
 objtool-enabled := $(or $(delay-objtool),$(CONFIG_NOINSTR_VALIDATION))
 
-# Reuse objtool_args defined in scripts/Makefile.lib if LTO or IBT is enabled.
-#
-# Add some more flags as needed.
-# --no-unreachable and --link might be added twice, but it is fine.
-#
-# Expand objtool_args to a simple variable to avoid circular reference.
+vmlinux-objtool-args-$(delay-objtool)			+= $(objtool-args-y)
+vmlinux-objtool-args-$(CONFIG_GCOV_KERNEL)		+= --no-unreachable
+vmlinux-objtool-args-$(CONFIG_NOINSTR_VALIDATION)	+= --noinstr $(if $(CONFIG_CPU_UNRET_ENTRY), --unret)
 
-objtool_args := \
-	$(if $(delay-objtool),$(objtool_args)) \
-	$(if $(CONFIG_NOINSTR_VALIDATION), --noinstr $(if $(CONFIG_CPU_UNRET_ENTRY), --unret)) \
-	$(if $(CONFIG_GCOV_KERNEL), --no-unreachable) \
-	--link
+objtool-args = $(vmlinux-objtool-args-y) --link
 
 # Link of vmlinux.o used for section mismatch analysis
 # ---------------------------------------------------------------------------