kbuild: add CONFIG_ASM_MODVERSIONS

Add CONFIG_ASM_MODVERSIONS. This allows to remove one if-conditional
nesting in scripts/Makefile.build.

scripts/Makefile.build is run every time Kbuild descends into a
sub-directory. So, I want to avoid $(wildcard ...) evaluation
where possible although computing $(wildcard ...) is so cheap that
it may not make measurable performance difference.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

arch/Kconfig

@@ -289,6 +289,13 @@ config ARCH_32BIT_OFF_T
 	  still support 32-bit off_t. This option is enabled for all such
 	  architectures explicitly.
 
+config HAVE_ASM_MODVERSIONS
+	bool
+	help
+	  This symbol should be selected by an architecure if it provides
+	  <asm/asm-prototypes.h> to support the module versioning for symbols
+	  exported from assembly code.
+
 config HAVE_REGS_AND_STACK_ACCESS_API
 	bool
 	help

arch/alpha/Kconfig

@@ -11,6 +11,7 @@ config ALPHA
 	select PCI_DOMAINS if PCI
 	select PCI_SYSCALL if PCI
 	select HAVE_AOUT
+	select HAVE_ASM_MODVERSIONS
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_PCSPKR_PLATFORM

arch/arm64/Kconfig

@@ -135,6 +135,7 @@ config ARM64
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select HAVE_ARCH_VMAP_STACK
 	select HAVE_ARM_SMCCC
+	select HAVE_ASM_MODVERSIONS
 	select HAVE_EBPF_JIT
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_CMPXCHG_DOUBLE

arch/ia64/Kconfig

@@ -17,6 +17,7 @@ config IA64
 	select FORCE_PCI if (!IA64_HP_SIM)
 	select PCI_DOMAINS if PCI
 	select PCI_SYSCALL if PCI
+	select HAVE_ASM_MODVERSIONS
 	select HAVE_UNSTABLE_SCHED_CLOCK
 	select HAVE_EXIT_THREAD
 	select HAVE_IDE

arch/m68k/Kconfig

@@ -14,6 +14,7 @@ config M68K
 	select DMA_DIRECT_REMAP if HAS_DMA && MMU && !COLDFIRE
 	select HAVE_IDE
 	select HAVE_AOUT if MMU
+	select HAVE_ASM_MODVERSIONS
 	select HAVE_DEBUG_BUGVERBOSE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_ATOMIC64

arch/mips/Kconfig

@@ -44,6 +44,7 @@ config MIPS
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if CPU_SUPPORTS_HUGEPAGES && 64BIT
+	select HAVE_ASM_MODVERSIONS
 	select HAVE_EBPF_JIT if (!CPU_MICROMIPS)
 	select HAVE_CONTEXT_TRACKING
 	select HAVE_COPY_THREAD_TLS

arch/powerpc/Kconfig

@@ -178,6 +178,7 @@ config PPC
 	select HAVE_ARCH_NVRAM_OPS
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_ASM_MODVERSIONS
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_CBPF_JIT			if !PPC64
 	select HAVE_STACKPROTECTOR		if PPC64 && $(cc-option,-mstack-protector-guard=tls -mstack-protector-guard-reg=r13)

arch/riscv/Kconfig

@@ -31,6 +31,7 @@ config RISCV
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_ATOMIC64 if !64BIT
 	select HAVE_ARCH_AUDITSYSCALL
+	select HAVE_ASM_MODVERSIONS
 	select HAVE_MEMBLOCK_NODE_MAP
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_FUTEX_CMPXCHG if FUTEX

arch/s390/Kconfig

@@ -131,6 +131,7 @@ config S390
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select HAVE_ARCH_VMAP_STACK
+	select HAVE_ASM_MODVERSIONS
 	select HAVE_EBPF_JIT if PACK_STACK && HAVE_MARCH_Z196_FEATURES
 	select HAVE_CMPXCHG_DOUBLE
 	select HAVE_CMPXCHG_LOCAL

arch/sparc/Kconfig

@@ -17,6 +17,7 @@ config SPARC
 	select ARCH_MIGHT_HAVE_PC_SERIO
 	select OF
 	select OF_PROMTREE
+	select HAVE_ASM_MODVERSIONS
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_ARCH_KGDB if !SMP || SPARC64

arch/um/Kconfig

@@ -9,6 +9,7 @@ config UML
 	select ARCH_NO_PREEMPT
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_SECCOMP_FILTER
+	select HAVE_ASM_MODVERSIONS
 	select HAVE_UID16
 	select HAVE_FUTEX_CMPXCHG if FUTEX
 	select HAVE_DEBUG_KMEMLEAK

arch/x86/Kconfig

@@ -147,6 +147,7 @@ config X86
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
 	select HAVE_ARCH_VMAP_STACK		if X86_64
 	select HAVE_ARCH_WITHIN_STACK_FRAMES
+	select HAVE_ASM_MODVERSIONS
 	select HAVE_CMPXCHG_DOUBLE
 	select HAVE_CMPXCHG_LOCAL
 	select HAVE_CONTEXT_TRACKING		if X86_64

init/Kconfig

@@ -1989,6 +1989,14 @@ config MODVERSIONS
 	  make them incompatible with the kernel you are running.  If
 	  unsure, say N.
 
+config ASM_MODVERSIONS
+	bool
+	default HAVE_ASM_MODVERSIONS && MODVERSIONS
+	help
+	  This enables module versioning for exported symbols also from
+	  assembly. This can be enabled only when the target architecture
+	  supports it.
+
 config MODULE_REL_CRCS
 	bool
 	depends on MODVERSIONS

scripts/Makefile.build

@@ -349,11 +349,7 @@ $(obj)/%.s: $(src)/%.S FORCE
 quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
       cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
 
-ifdef CONFIG_MODVERSIONS
-
-ASM_PROTOTYPES := $(wildcard $(srctree)/arch/$(SRCARCH)/include/asm/asm-prototypes.h)
-
-ifneq ($(ASM_PROTOTYPES),)
+ifdef CONFIG_ASM_MODVERSIONS
 
 # versioning matches the C process described above, with difference that
 # we parse asm-prototypes.h C header to get function definitions.
@@ -369,7 +365,6 @@ cmd_modversions_S =								\
 		rm -f $(@D)/.tmp_$(@F:.o=.ver);					\
 	fi
 endif
-endif
 
 $(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
 	$(call if_changed_rule,as_o_S)