[PATCH v2 1/2] arch: Introduce ARCH_HAS_CPUMASK_BITS

[Yair Podemsky]

Some architectures set and maintain the mm_cpumask bits when loading
or removing process from cpu.
This Kconfig will mark those to allow different behavior between
kernels that maintain the mm_cpumask and those that do not.

Signed-off-by: Yair Podemsky <ypodemsk at redhat.com>
---
 arch/Kconfig         | 8 ++++++++
 arch/arm/Kconfig     | 1 +
 arch/powerpc/Kconfig | 1 +
 arch/s390/Kconfig    | 1 +
 arch/sparc/Kconfig   | 1 +
 arch/x86/Kconfig     | 1 +
 6 files changed, 13 insertions(+)

diff --git a/arch/Kconfig b/arch/Kconfig
index 205fd23e0cad..953fbfa5a2ad 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1466,6 +1466,14 @@ config ARCH_HAS_NONLEAF_PMD_YOUNG
 	  address translations. Page table walkers that clear the accessed bit
 	  may use this capability to reduce their search space.
 
+config ARCH_HAS_CPUMASK_BITS
+	bool
+	help
+	  Architectures that select this option set bits on the mm_cpumask
+	  to mark which cpus loaded the mm, The mask can then be used to
+	  control mm specific actions such as tlb_flush.
+
+
 source "kernel/gcov/Kconfig"
 
 source "scripts/gcc-plugins/Kconfig"
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 0fb4b218f665..cd20e96bc1dc 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -70,6 +70,7 @@ config ARM
 	select GENERIC_SMP_IDLE_THREAD
 	select HARDIRQS_SW_RESEND
 	select HAS_IOPORT
+	select ARCH_HAS_CPUMASK_BITS
 	select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
 	select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
 	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index bff5820b7cda..c9218722aa2f 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -156,6 +156,7 @@ config PPC
 	select ARCH_HAS_TICK_BROADCAST		if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAS_UACCESS_FLUSHCACHE
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_HAS_CPUMASK_BITS
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select ARCH_KEEP_MEMBLOCK
 	select ARCH_MIGHT_HAVE_PC_PARPORT
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 6dab9c1be508..60bf29bc3f87 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -84,6 +84,7 @@ config S390
 	select ARCH_HAS_SYSCALL_WRAPPER
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_HAS_VDSO_DATA
+	select ARCH_HAS_CPUMASK_BITS
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select ARCH_INLINE_READ_LOCK
 	select ARCH_INLINE_READ_LOCK_BH
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 8535e19062f6..e8bf4d769306 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -99,6 +99,7 @@ config SPARC64
 	select ARCH_HAS_PTE_SPECIAL
 	select PCI_DOMAINS if PCI
 	select ARCH_HAS_GIGANTIC_PAGE
+	select ARCH_HAS_CPUMASK_BITS
 	select HAVE_SOFTIRQ_ON_OWN_STACK
 	select HAVE_SETUP_PER_CPU_AREA
 	select NEED_PER_CPU_EMBED_FIRST_CHUNK
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 53bab123a8ee..b351421695f3 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -185,6 +185,7 @@ config X86
 	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
 	select HAVE_ARCH_STACKLEAK
 	select HAVE_ARCH_TRACEHOOK
+	select ARCH_HAS_CPUMASK_BITS
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
 	select HAVE_ARCH_USERFAULTFD_WP         if X86_64 && USERFAULTFD
-- 
2.39.3