[PATCH v3 07/23] mm/vma: add append_vma_flags() helper

["Lorenzo Stoakes (Oracle)" <ljs@kernel.org>]

In order to be able to efficiently combine VMA flag masks with additional
VMA flag bits we need to extend the concept introduced in mk_vma_flags()
and __mk_vma_flags() by allowing the specification of a VMA flag mask to
append VMA flag bits to.

Update __mk_vma_flags() to allow for this and update mk_vma_flags()
accordingly, and also provide append_vma_flags() to allow for the caller
to specify which VMA flags mask to append to.

Finally, update the VMA flags tests to reflect the change.

Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
---
 include/linux/mm.h              | 20 ++++++++++++++------
 tools/testing/vma/include/dup.h | 14 +++++++-------
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index b75e089dfd65..0c35423177bf 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1047,13 +1047,11 @@ static __always_inline void vma_flags_set_flag(vma_flags_t *flags,
 	__set_bit((__force int)bit, bitmap);
 }
 
-static __always_inline vma_flags_t __mk_vma_flags(size_t count,
-		const vma_flag_t *bits)
+static __always_inline vma_flags_t __mk_vma_flags(vma_flags_t flags,
+		size_t count, const vma_flag_t *bits)
 {
-	vma_flags_t flags;
 	int i;
 
-	vma_flags_clear_all(&flags);
 	for (i = 0; i < count; i++)
 		vma_flags_set_flag(&flags, bits[i]);
 	return flags;
@@ -1069,8 +1067,18 @@ static __always_inline vma_flags_t __mk_vma_flags(size_t count,
  * The compiler cleverly optimises away all of the work and this ends up being
  * equivalent to aggregating the values manually.
  */
-#define mk_vma_flags(...) __mk_vma_flags(COUNT_ARGS(__VA_ARGS__), \
-					 (const vma_flag_t []){__VA_ARGS__})
+#define mk_vma_flags(...) __mk_vma_flags(EMPTY_VMA_FLAGS,			\
+		COUNT_ARGS(__VA_ARGS__), (const vma_flag_t []){__VA_ARGS__})
+
+/*
+ * Helper macro which acts like mk_vma_flags, only appending to a copy of the
+ * specified flags rather than establishing new flags. E.g.:
+ *
+ * vma_flags_t flags = append_vma_flags(VMA_STACK_DEFAULT_FLAGS, VMA_STACK_BIT,
+ *              VMA_ACCOUNT_BIT);
+ */
+#define append_vma_flags(flags, ...) __mk_vma_flags(flags,			\
+		COUNT_ARGS(__VA_ARGS__), (const vma_flag_t []){__VA_ARGS__})
 
 /*
  * Test whether a specific VMA flag is set, e.g.:
diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h
index 3005e33d1ede..a2f311b5ea82 100644
--- a/tools/testing/vma/include/dup.h
+++ b/tools/testing/vma/include/dup.h
@@ -854,21 +854,21 @@ static inline void vm_flags_clear(struct vm_area_struct *vma,
 	vma_flags_clear_word(&vma->flags, flags);
 }
 
-static __always_inline vma_flags_t __mk_vma_flags(size_t count,
-		const vma_flag_t *bits)
+static __always_inline vma_flags_t __mk_vma_flags(vma_flags_t flags,
+		size_t count, const vma_flag_t *bits)
 {
-	vma_flags_t flags;
 	int i;
 
-	vma_flags_clear_all(&flags);
 	for (i = 0; i < count; i++)
 		vma_flags_set_flag(&flags, bits[i]);
-
 	return flags;
 }
 
-#define mk_vma_flags(...) __mk_vma_flags(COUNT_ARGS(__VA_ARGS__),	\
-		(const vma_flag_t []){__VA_ARGS__})
+#define mk_vma_flags(...) __mk_vma_flags(EMPTY_VMA_FLAGS,			\
+		COUNT_ARGS(__VA_ARGS__), (const vma_flag_t []){__VA_ARGS__})
+
+#define append_vma_flags(flags, ...) __mk_vma_flags(flags,			\
+		COUNT_ARGS(__VA_ARGS__), (const vma_flag_t []){__VA_ARGS__})
 
 static __always_inline bool vma_flags_test(const vma_flags_t *flags,
 		vma_flag_t bit)
-- 
2.53.0