linux-kernel - [PATCH 2/4] mm: remove CONFIG_ARCH_USES_HIGH_VMA

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Message-ID: <20250506095224.176085-3-revest@chromium.org>
Date: Tue,  6 May 2025 11:52:22 +0200
From: Florent Revest <revest@...omium.org>
To: linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Cc: catalin.marinas@....com,
	will@...nel.org,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	hpa@...or.com,
	akpm@...ux-foundation.org,
	broonie@...nel.org,
	thiago.bauermann@...aro.org,
	jackmanb@...gle.com,
	Florent Revest <revest@...omium.org>
Subject: [PATCH 2/4] mm: remove CONFIG_ARCH_USES_HIGH_VMA_FLAGS

Over the years, include/linux/mm.h has grown to use high VMA flags bits
in various ways. Some usages, like mseal(), are guarded by CONFIG_64BIT
while others like CONFIG_ARM64_MTE select
CONFIG_ARCH_USES_HIGH_VMA_FLAGS and depend on the VM_HIGH_ARCH* macros that
are guarded by that config.

Since CONFIG_ARCH_USES_HIGH_VMA_FLAGS only guards bit mask definitions,
it is safe to use on any CONFIG_64BIT config. Additionally, since all
configs that currently select CONFIG_ARCH_USES_HIGH_VMA_FLAGS depend on
CONFIG_64BIT, there should be no regressions.

Signed-off-by: Florent Revest <revest@...omium.org>
---
 arch/arm64/Kconfig   | 3 ---
 arch/powerpc/Kconfig | 1 -
 arch/x86/Kconfig     | 2 --
 include/linux/mm.h   | 4 ++--
 mm/Kconfig           | 2 --
 5 files changed, 2 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a182295e6f08b..2a0d45b16b7fd 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -2149,7 +2149,6 @@ config ARM64_MTE
 	# Required for tag checking in the uaccess routines
 	select ARM64_PAN
 	select ARCH_HAS_SUBPAGE_FAULTS
-	select ARCH_USES_HIGH_VMA_FLAGS
 	select ARCH_USES_PG_ARCH_2
 	select ARCH_USES_PG_ARCH_3
 	help
@@ -2196,7 +2195,6 @@ menu "ARMv8.9 architectural features"
 config ARM64_POE
 	prompt "Permission Overlay Extension"
 	def_bool y
-	select ARCH_USES_HIGH_VMA_FLAGS
 	select ARCH_HAS_PKEYS
 	help
 	  The Permission Overlay Extension is used to implement Memory
@@ -2235,7 +2233,6 @@ config ARM64_GCS
 	bool "Enable support for Guarded Control Stack (GCS)"
 	default y
 	select ARCH_HAS_USER_SHADOW_STACK
-	select ARCH_USES_HIGH_VMA_FLAGS
 	depends on !UPROBES
 	help
 	  Guarded Control Stack (GCS) provides support for a separate
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 6722625a406a0..e444191206b32 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -1043,7 +1043,6 @@ config PPC_MEM_KEYS
 	def_bool y
 	depends on PPC_BOOK3S_64
 	depends on PPC_64S_HASH_MMU
-	select ARCH_USES_HIGH_VMA_FLAGS
 	select ARCH_HAS_PKEYS
 	help
 	  Memory Protection Keys provides a mechanism for enforcing
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4b9f378e05f6b..e74ba77a066e6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1818,7 +1818,6 @@ config X86_INTEL_MEMORY_PROTECTION_KEYS
 	def_bool y
 	# Note: only available in 64-bit mode
 	depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
-	select ARCH_USES_HIGH_VMA_FLAGS
 	select ARCH_HAS_PKEYS
 	help
 	  Memory Protection Keys provides a mechanism for enforcing
@@ -1900,7 +1899,6 @@ config X86_USER_SHADOW_STACK
 	bool "X86 userspace shadow stack"
 	depends on AS_WRUSS
 	depends on X86_64
-	select ARCH_USES_HIGH_VMA_FLAGS
 	select ARCH_HAS_USER_SHADOW_STACK
 	select X86_CET
 	help
diff --git a/include/linux/mm.h b/include/linux/mm.h
index fdda6b16263b3..da8f99a026deb 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -297,7 +297,7 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_NOHUGEPAGE	0x40000000	/* MADV_NOHUGEPAGE marked this vma */
 #define VM_MERGEABLE	0x80000000	/* KSM may merge identical pages */
 
-#ifdef CONFIG_ARCH_USES_HIGH_VMA_FLAGS
+#ifdef CONFIG_64BIT
 #define VM_HIGH_ARCH_BIT_0	32	/* bit only usable on 64-bit architectures */
 #define VM_HIGH_ARCH_BIT_1	33	/* bit only usable on 64-bit architectures */
 #define VM_HIGH_ARCH_BIT_2	34	/* bit only usable on 64-bit architectures */
@@ -312,7 +312,7 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_HIGH_ARCH_4	BIT(VM_HIGH_ARCH_BIT_4)
 #define VM_HIGH_ARCH_5	BIT(VM_HIGH_ARCH_BIT_5)
 #define VM_HIGH_ARCH_6	BIT(VM_HIGH_ARCH_BIT_6)
-#endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */
+#endif /* CONFIG_64BIT */
 
 #ifdef CONFIG_ARCH_HAS_PKEYS
 # define VM_PKEY_SHIFT VM_HIGH_ARCH_BIT_0
diff --git a/mm/Kconfig b/mm/Kconfig
index e113f713b4938..1fff7f8bfa96f 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1127,8 +1127,6 @@ config DEVICE_PRIVATE
 config VMAP_PFN
 	bool
 
-config ARCH_USES_HIGH_VMA_FLAGS
-	bool
 config ARCH_HAS_PKEYS
 	bool
 
-- 
2.49.0.967.g6a0df3ecc3-goog