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From:   Liam Howlett <liam.howlett@oracle.com>
To:     "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
CC:     Liam Howlett <liam.howlett@oracle.com>,
        Liam Howlett <liam.howlett@oracle.com>
Subject: [PATCH v2 15/44] mm: Change mprotect_fixup to vma iterator
Thread-Topic: [PATCH v2 15/44] mm: Change mprotect_fixup to vma iterator
Thread-Index: AQHZITojC1aO2fk7xUeU8jhHjC9bew==
Date:   Thu, 5 Jan 2023 19:15:56 +0000
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From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

Use the vma iterator so that the iterator can be invalidated or updated
to avoid each caller doing so.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
 fs/exec.c          |  5 ++++-
 include/linux/mm.h |  6 +++---
 mm/mprotect.c      | 47 ++++++++++++++++++++++------------------------
 3 files changed, 29 insertions(+), 29 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index ab913243a367..b98647eeae9f 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -758,6 +758,7 @@ int setup_arg_pages(struct linux_binprm *bprm,
 	unsigned long stack_expand;
 	unsigned long rlim_stack;
 	struct mmu_gather tlb;
+	struct vma_iterator vmi;
=20
 #ifdef CONFIG_STACK_GROWSUP
 	/* Limit stack size */
@@ -812,8 +813,10 @@ int setup_arg_pages(struct linux_binprm *bprm,
 	vm_flags |=3D mm->def_flags;
 	vm_flags |=3D VM_STACK_INCOMPLETE_SETUP;
=20
+	vma_iter_init(&vmi, mm, vma->vm_start);
+
 	tlb_gather_mmu(&tlb, mm);
-	ret =3D mprotect_fixup(&tlb, vma, &prev, vma->vm_start, vma->vm_end,
+	ret =3D mprotect_fixup(&vmi, &tlb, vma, &prev, vma->vm_start, vma->vm_end=
,
 			vm_flags);
 	tlb_finish_mmu(&tlb);
=20
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9c790c88f691..98c91a25d257 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2188,9 +2188,9 @@ extern unsigned long change_protection(struct mmu_gat=
her *tlb,
 			      struct vm_area_struct *vma, unsigned long start,
 			      unsigned long end, pgprot_t newprot,
 			      unsigned long cp_flags);
-extern int mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *v=
ma,
-			  struct vm_area_struct **pprev, unsigned long start,
-			  unsigned long end, unsigned long newflags);
+extern int mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb=
,
+	  struct vm_area_struct *vma, struct vm_area_struct **pprev,
+	  unsigned long start, unsigned long end, unsigned long newflags);
=20
 /*
  * doesn't attempt to fault and will return short.
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 908df12caa26..7e6cb2165000 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -548,9 +548,9 @@ static const struct mm_walk_ops prot_none_walk_ops =3D =
{
 };
=20
 int
-mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma,
-	       struct vm_area_struct **pprev, unsigned long start,
-	       unsigned long end, unsigned long newflags)
+mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
+	       struct vm_area_struct *vma, struct vm_area_struct **pprev,
+	       unsigned long start, unsigned long end, unsigned long newflags)
 {
 	struct mm_struct *mm =3D vma->vm_mm;
 	unsigned long oldflags =3D vma->vm_flags;
@@ -605,7 +605,7 @@ mprotect_fixup(struct mmu_gather *tlb, struct vm_area_s=
truct *vma,
 	 * First try to merge with previous and/or next vma.
 	 */
 	pgoff =3D vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
-	*pprev =3D vma_merge(mm, *pprev, start, end, newflags,
+	*pprev =3D vmi_vma_merge(vmi, mm, *pprev, start, end, newflags,
 			   vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
 			   vma->vm_userfaultfd_ctx, anon_vma_name(vma));
 	if (*pprev) {
@@ -617,13 +617,13 @@ mprotect_fixup(struct mmu_gather *tlb, struct vm_area=
_struct *vma,
 	*pprev =3D vma;
=20
 	if (start !=3D vma->vm_start) {
-		error =3D split_vma(mm, vma, start, 1);
+		error =3D vmi_split_vma(vmi, mm, vma, start, 1);
 		if (error)
 			goto fail;
 	}
=20
 	if (end !=3D vma->vm_end) {
-		error =3D split_vma(mm, vma, end, 0);
+		error =3D vmi_split_vma(vmi, mm, vma, end, 0);
 		if (error)
 			goto fail;
 	}
@@ -672,7 +672,7 @@ static int do_mprotect_pkey(unsigned long start, size_t=
 len,
 	const bool rier =3D (current->personality & READ_IMPLIES_EXEC) &&
 				(prot & PROT_READ);
 	struct mmu_gather tlb;
-	MA_STATE(mas, &current->mm->mm_mt, 0, 0);
+	struct vma_iterator vmi;
=20
 	start =3D untagged_addr(start);
=20
@@ -704,8 +704,8 @@ static int do_mprotect_pkey(unsigned long start, size_t=
 len,
 	if ((pkey !=3D -1) && !mm_pkey_is_allocated(current->mm, pkey))
 		goto out;
=20
-	mas_set(&mas, start);
-	vma =3D mas_find(&mas, ULONG_MAX);
+	vma_iter_init(&vmi, current->mm, start);
+	vma =3D vma_find(&vmi, end);
 	error =3D -ENOMEM;
 	if (!vma)
 		goto out;
@@ -728,18 +728,22 @@ static int do_mprotect_pkey(unsigned long start, size=
_t len,
 		}
 	}
=20
+	prev =3D vma_prev(&vmi);
 	if (start > vma->vm_start)
 		prev =3D vma;
-	else
-		prev =3D mas_prev(&mas, 0);
=20
 	tlb_gather_mmu(&tlb, current->mm);
-	for (nstart =3D start ; ; ) {
+	nstart =3D start;
+	tmp =3D vma->vm_start;
+	for_each_vma_range(vmi, vma, end) {
 		unsigned long mask_off_old_flags;
 		unsigned long newflags;
 		int new_vma_pkey;
=20
-		/* Here we know that vma->vm_start <=3D nstart < vma->vm_end. */
+		if (vma->vm_start !=3D tmp) {
+			error =3D -ENOMEM;
+			break;
+		}
=20
 		/* Does the application expect PROT_READ to imply PROT_EXEC */
 		if (rier && (vma->vm_flags & VM_MAYEXEC))
@@ -782,25 +786,18 @@ static int do_mprotect_pkey(unsigned long start, size=
_t len,
 				break;
 		}
=20
-		error =3D mprotect_fixup(&tlb, vma, &prev, nstart, tmp, newflags);
+		error =3D mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags);
 		if (error)
 			break;
=20
 		nstart =3D tmp;
-
-		if (nstart < prev->vm_end)
-			nstart =3D prev->vm_end;
-		if (nstart >=3D end)
-			break;
-
-		vma =3D find_vma(current->mm, prev->vm_end);
-		if (!vma || vma->vm_start !=3D nstart) {
-			error =3D -ENOMEM;
-			break;
-		}
 		prot =3D reqprot;
 	}
 	tlb_finish_mmu(&tlb);
+
+	if (vma_iter_end(&vmi) < end)
+		error =3D -ENOMEM;
+
 out:
 	mmap_write_unlock(current->mm);
 	return error;
--=20
2.35.1