arch: add ARCH_HAS_SET_MEMORY config

Currently, there's no good way to test for the presence of
set_memory_ro/rw/x/nx() helpers implemented by archs such as
x86, arm, arm64 and s390.

There's DEBUG_SET_MODULE_RONX and DEBUG_RODATA, however both
don't really reflect that: set_memory_*() are also available
even when DEBUG_SET_MODULE_RONX is turned off, and DEBUG_RODATA
is set by parisc, but doesn't implement above functions. Thus,
add ARCH_HAS_SET_MEMORY that is selected by mentioned archs,
where generic code can test against this.

This also allows later on to move DEBUG_SET_MODULE_RONX out of
the arch specific Kconfig to define it only once depending on
ARCH_HAS_SET_MEMORY.
Suggested-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/Kconfig

@@ -222,6 +222,10 @@ config GENERIC_SMP_IDLE_THREAD
 config GENERIC_IDLE_POLL_SETUP
        bool
 
+# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
+config ARCH_HAS_SET_MEMORY
+	bool
+
 # Select if arch init_task initializer is different to init/init_task.c
 config ARCH_INIT_TASK
        bool

arch/arm/Kconfig

@@ -4,6 +4,7 @@ config ARM
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_ELF_RANDOMIZE
+	select ARCH_HAS_SET_MEMORY
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select ARCH_HAS_GCOV_PROFILE_ALL

arch/arm64/Kconfig

@@ -12,6 +12,7 @@ config ARM64
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
+	select ARCH_HAS_SET_MEMORY
 	select ARCH_HAS_SG_CHAIN
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_USE_CMPXCHG_LOCKREF

arch/s390/Kconfig

@@ -72,6 +72,7 @@ config S390
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
+	select ARCH_HAS_SET_MEMORY
 	select ARCH_HAS_SG_CHAIN
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG

arch/x86/Kconfig

@@ -53,6 +53,7 @@ config X86
 	select ARCH_HAS_KCOV			if X86_64
 	select ARCH_HAS_MMIO_FLUSH
 	select ARCH_HAS_PMEM_API		if X86_64
+	select ARCH_HAS_SET_MEMORY
 	select ARCH_HAS_SG_CHAIN
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG