kbuild: factor out the common objtool arguments

scripts/Makefile.build and scripts/link-vmlinux.sh have similar setups
for the objtool arguments.

It was difficult to factor out them because all the vmlinux build rules
were written in a shell script. It is somewhat tedious to touch the two
files every time a new objtool option is supported.

To reduce the code duplication, move the objtool for vmlinux.o into
scripts/Makefile.vmlinux_o. Then, move the common macros to Makefile.lib
so they are shared between Makefile.build and Makefile.vmlinux_o.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)

scripts/Makefile.lib

@@ -225,6 +225,32 @@ dtc_cpp_flags  = -Wp,-MMD,$(depfile).pre.tmp -nostdinc                    \
 		 $(addprefix -I,$(DTC_INCLUDE))                          \
 		 -undef -D__DTS__
 
+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_SLS), --sls)					\
+	$(if $(CONFIG_STACK_VALIDATION), --stackval)			\
+	$(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call)		\
+	--uaccess							\
+	$(if $(delay-objtool), --link)					\
+	$(if $(part-of-module), --module)				\
+	$(if $(CONFIG_GCOV_KERNEL), --no-unreachable)
+
+delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT))
+
+cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
+cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
+
+endif # CONFIG_OBJTOOL
+
 # Useful for describing the dependency of composite objects
 # Usage:
 #   $(call multi_depend, multi_used_targets, suffix_to_remove, suffix_to_add)