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.

Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
---
 include/linux/mm.h                 | 28 ++++++++++++++++++++++++++++
 tools/testing/vma/include/custom.h | 11 -----------
 tools/testing/vma/include/dup.h    | 21 +++++++++++++++++++++
 3 files changed, 49 insertions(+), 11 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 42d346684678..b170cee95e25 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1207,6 +1207,34 @@ 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.
  *
diff --git a/tools/testing/vma/include/custom.h b/tools/testing/vma/include/custom.h
index 8f33df02816a..2c498e713fbd 100644
--- a/tools/testing/vma/include/custom.h
+++ b/tools/testing/vma/include/custom.h
@@ -102,16 +102,5 @@ static inline unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
 	return PAGE_SIZE;
 }
 
-/* Place here until needed in the kernel code. */
-static __always_inline bool vma_flags_same_mask(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);
-}
-#define vma_flags_same(flags, ...) \
-	vma_flags_same_mask(flags, mk_vma_flags(__VA_ARGS__))
 #define VMA_SPECIAL_FLAGS mk_vma_flags(VMA_IO_BIT, VMA_DONTEXPAND_BIT, \
 				       VMA_PFNMAP_BIT, VMA_MIXEDMAP_BIT)
diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h
index 47ad01c5d15e..29a6f62b01db 100644
--- a/tools/testing/vma/include/dup.h
+++ b/tools/testing/vma/include/dup.h
@@ -954,6 +954,27 @@ static __always_inline vma_flags_t vma_flags_diff_pair(const vma_flags_t *flags,
 	return dst;
 }
 
+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);
+}
+
+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);
+}
+
+#define vma_flags_same(flags, ...) \
+	vma_flags_same_mask(flags, mk_vma_flags(__VA_ARGS__))
+
 static inline bool vma_test_all_mask(const struct vm_area_struct *vma,
 				     vma_flags_t flags)
 {
-- 
2.53.0