arch/arm64: Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option

The arm64 architecture uses either an LL/SC loop (old systems) or an LSE
stadd instruction (new systems) to implement this_cpu_add(), both of which
are NMI safe.  This means that the old and more-efficient srcu_read_lock()
may be used in NMI context, without the need for srcu_read_lock_nmisafe().
Therefore, add the new Kconfig option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to
arch/arm64/Kconfig, which will cause NEED_SRCU_NMI_SAFE to be deselected,
thus preserving the current srcu_read_lock() behavior.

Link: https://lore.kernel.org/all/[email protected]/

Suggested-by: Neeraj Upadhyay <[email protected]>
Suggested-by: Frederic Weisbecker <[email protected]>
Suggested-by: Boqun Feng <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: John Ogness <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: <[email protected]>

Author: paulmckrcu

arch/arm64/Kconfig

@@ -31,6 +31,7 @@ config ARM64
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_KEEPINITRD
 	select ARCH_HAS_MEMBARRIER_SYNC_CORE
+	select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 	select ARCH_HAS_PTE_DEVMAP
 	select ARCH_HAS_PTE_SPECIAL