From 3ee584538259c356c66146ac46f2e4fd2ba28bee Mon Sep 17 00:00:00 2001
From: "Lorenzo Stoakes (Oracle)" <ljs@kernel.org>
Date: Fri, 20 Mar 2026 19:38:27 +0000
Subject: mm/vma: introduce vma_flags_same[_mask/_pair]()

Add helpers to determine if two sets of VMA flags are precisely the same,
that is - that every flag set one is set in another, and neither contain
any flags not set in the other.

We also introduce vma_flags_same_pair() for cases where we want to compare
two sets of VMA flags which are both non-const values.

Also update the VMA tests to reflect the change, we already implicitly
test that this functions correctly having used it for testing purposes
previously.

Link: https://lkml.kernel.org/r/4f764bf619e77205837c7c819b62139ef6337ca3.1774034900.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Ondrej Mosnacek <omosnace@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/mm.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

(limited to 'include/linux')

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5b85ffc2760c..1f3e9100164d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1202,6 +1202,34 @@ static __always_inline vma_flags_t vma_flags_diff_pair(const vma_flags_t *flags,
 	return dst;
 }
 
+/* Determine if flags and flags_other have precisely the same flags set. */
+static __always_inline bool vma_flags_same_pair(const vma_flags_t *flags,
+						const vma_flags_t *flags_other)
+{
+	const unsigned long *bitmap = flags->__vma_flags;
+	const unsigned long *bitmap_other = flags_other->__vma_flags;
+
+	return bitmap_equal(bitmap, bitmap_other, NUM_VMA_FLAG_BITS);
+}
+
+/* Determine if flags and flags_other have precisely the same flags set.  */
+static __always_inline bool vma_flags_same_mask(const vma_flags_t *flags,
+						vma_flags_t flags_other)
+{
+	const unsigned long *bitmap = flags->__vma_flags;
+	const unsigned long *bitmap_other = flags_other.__vma_flags;
+
+	return bitmap_equal(bitmap, bitmap_other, NUM_VMA_FLAG_BITS);
+}
+
+/*
+ * Helper macro to determine if only the specific flags are set, e.g.:
+ *
+ * if (vma_flags_same(&flags, VMA_WRITE_BIT) { ... }
+ */
+#define vma_flags_same(flags, ...) \
+	vma_flags_same_mask(flags, mk_vma_flags(__VA_ARGS__))
+
 /*
  * Helper to test that ALL specified flags are set in a VMA.
  *
-- 
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