From: Liam R. Howlett <Liam.Howlett@oracle.com>
Date: Tue, 28 Oct 2025 18:21:31 +0000 (-0400)
Subject: mm/userfaultfd: Introduce uffd_info struct for arguments
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7f0da82d79ad5486d48dc4c91a31a36dbf255cc0;p=users%2Fjedix%2Flinux-maple.git

mm/userfaultfd: Introduce uffd_info struct for arguments

Introduce a helper function so that any updates to any memory type does
not require all memory types to use a new function definition.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---

diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 38aac8085c4b..ba61ff6eba00 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -116,6 +116,25 @@ struct vm_uffd_ops {
 			unsigned long src_addr);
 };
 
+struct uffd_info {
+	unsigned long dst_addr;			/* Target address */
+	unsigned long src_addr;			/* Source address */
+	unsigned long len;			/* Total length to copy */
+
+	struct vm_area_struct *dst_vma;		/* Target vma */
+	unsigned long increment;		/* Size of each operation */
+	bool wp;				/* Operation is requesting write protection */
+	struct folio **foliop;			/* folio pointer for retry */
+	const struct vm_uffd_ops *uffd_ops;	/* The vma uffd_ops pointer */
+};
+
+#define UFFD_STRUCT_INIT(__dst_addr, __src_addr, __len, __wp) {	\
+	.dst_addr = (__dst_addr),					\
+	.src_addr = (__src_addr),					\
+	.len = (__len),							\
+	.wp = (__wp),							\
+}
+
 #define MFILL_ATOMIC_MODE_BITS (const_ilog2(NR_MFILL_ATOMIC_MODES - 1) + 1)
 #define MFILL_ATOMIC_BIT(nr) BIT(MFILL_ATOMIC_MODE_BITS + (nr))
 #define MFILL_ATOMIC_FLAG(nr) ((__force uffd_flags_t) MFILL_ATOMIC_BIT(nr))
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 6fa840bdeee0..931b428dd7ec 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -96,18 +96,21 @@ static struct vm_area_struct *uffd_lock_vma(struct mm_struct *mm,
 	return vma;
 }
 
-static struct vm_area_struct *uffd_mfill_lock(struct mm_struct *dst_mm,
-					      unsigned long dst_start,
-					      unsigned long len)
+static int uffd_mfill_lock(struct mm_struct *dst_mm, struct uffd_info *us)
 {
 	struct vm_area_struct *dst_vma;
 
-	dst_vma = uffd_lock_vma(dst_mm, dst_start);
-	if (IS_ERR(dst_vma) || validate_dst_vma(dst_vma, dst_start + len))
-		return dst_vma;
+	dst_vma = uffd_lock_vma(dst_mm, us->dst_addr);
+	if (IS_ERR(dst_vma))
+		return PTR_ERR(dst_vma);
+
+	if (validate_dst_vma(dst_vma, us->dst_addr + us->len)) {
+		us->dst_vma = dst_vma;
+		return 0;
+	}
 
 	vma_end_read(dst_vma);
-	return ERR_PTR(-ENOENT);
+	return -ENOENT;
 }
 
 static void uffd_mfill_unlock(struct vm_area_struct *vma)
@@ -117,24 +120,24 @@ static void uffd_mfill_unlock(struct vm_area_struct *vma)
 
 #else
 
-static struct vm_area_struct *uffd_mfill_lock(struct mm_struct *dst_mm,
-					      unsigned long dst_start,
-					      unsigned long len)
+static int uffd_mfill_lock(struct mm_struct *dst_mm, struct uffd_info *us)
 {
 	struct vm_area_struct *dst_vma;
 
 	mmap_read_lock(dst_mm);
-	dst_vma = find_vma_and_prepare_anon(dst_mm, dst_start);
+	dst_vma = find_vma_and_prepare_anon(dst_mm, uf->dst_addr);
 	if (IS_ERR(dst_vma))
 		goto out_unlock;
 
-	if (validate_dst_vma(dst_vma, dst_start + len))
-		return dst_vma;
+	if (validate_dst_vma(dst_vma, uf->dst_addr, uf->len)) {
+		us->dst_vma = dst_vma;
+		return 0;
+	}
 
-	dst_vma = ERR_PTR(-ENOENT);
+	dst_vma = -ENOENT;
 out_unlock:
 	mmap_read_unlock(dst_mm);
-	return dst_vma;
+	return PTR_ERR(dst_vma);
 }
 
 static void uffd_mfill_unlock(struct vm_area_struct *vma)
@@ -647,6 +650,8 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx,
 	struct folio *folio;
 	const struct vm_uffd_ops *uffd_ops;
 	unsigned long increment;
+	struct uffd_info info = UFFD_STRUCT_INIT(dst_start, src_start, len,
+						 flags & MFILL_ATOMIC_WP);
 
 	/*
 	 * Sanitize the command parameters:
@@ -668,11 +673,11 @@ retry:
 	 * Make sure the vma is not shared, that the dst range is
 	 * both valid and fully within a single existing vma.
 	 */
-	dst_vma = uffd_mfill_lock(dst_mm, dst_start, len);
-	if (IS_ERR(dst_vma)) {
-		err = PTR_ERR(dst_vma);
+	err = uffd_mfill_lock(dst_mm, &info);
+	if (err)
 		goto out;
-	}
+
+	dst_vma = info.dst_vma;
 	uffd_ops = vma_get_uffd_ops(dst_vma);
 	if (WARN_ON_ONCE(!uffd_ops->increment)) {
 		increment = PAGE_SIZE;
@@ -690,6 +695,7 @@ retry:
 	    uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE))
 		goto out_unlock;
 
+	info.increment = increment;
 	while (src_addr < src_start + len) {
 		VM_WARN_ON_ONCE(dst_addr >= dst_start + len);