mm: isolate mmap internal logic to mm/vma.c

In previous commits we effected improvements to the mmap() logic in
mmap_region() and its newly introduced internal implementation function
__mmap_region().

However as these changes are intended to be backported, we kept the delta
as small as is possible and made as few changes as possible to the newly
introduced mm/vma.* files.

Take the opportunity to move this logic to mm/vma.c which not only
isolates it, but also makes it available for later userland testing which
can help us catch such logic errors far earlier.

Link: https://lkml.kernel.org/r/93fc2c3aa37dd30590b7e4ee067dfd832007bf7e.1729858176.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 4 insertions, 93 deletions

diff --git a/mm/vma.h b/mm/vma.h
index d58068c0ff2e..388d34748674 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -165,99 +165,6 @@ static inline int vma_iter_store_gfp(struct vma_iterator *vmi,
 	return 0;
 }
 
-#ifdef CONFIG_MMU
-/*
- * init_vma_munmap() - Initializer wrapper for vma_munmap_struct
- * @vms: The vma munmap struct
- * @vmi: The vma iterator
- * @vma: The first vm_area_struct to munmap
- * @start: The aligned start address to munmap
- * @end: The aligned end address to munmap
- * @uf: The userfaultfd list_head
- * @unlock: Unlock after the operation.  Only unlocked on success
- */
-static inline void init_vma_munmap(struct vma_munmap_struct *vms,
-		struct vma_iterator *vmi, struct vm_area_struct *vma,
-		unsigned long start, unsigned long end, struct list_head *uf,
-		bool unlock)
-{
-	vms->vmi = vmi;
-	vms->vma = vma;
-	if (vma) {
-		vms->start = start;
-		vms->end = end;
-	} else {
-		vms->start = vms->end = 0;
-	}
-	vms->unlock = unlock;
-	vms->uf = uf;
-	vms->vma_count = 0;
-	vms->nr_pages = vms->locked_vm = vms->nr_accounted = 0;
-	vms->exec_vm = vms->stack_vm = vms->data_vm = 0;
-	vms->unmap_start = FIRST_USER_ADDRESS;
-	vms->unmap_end = USER_PGTABLES_CEILING;
-	vms->clear_ptes = false;
-}
-#endif
-
-int vms_gather_munmap_vmas(struct vma_munmap_struct *vms,
-		struct ma_state *mas_detach);
-
-void vms_complete_munmap_vmas(struct vma_munmap_struct *vms,
-		struct ma_state *mas_detach);
-
-void vms_clean_up_area(struct vma_munmap_struct *vms,
-		struct ma_state *mas_detach);
-
-/*
- * reattach_vmas() - Undo any munmap work and free resources
- * @mas_detach: The maple state with the detached maple tree
- *
- * Reattach any detached vmas and free up the maple tree used to track the vmas.
- */
-static inline void reattach_vmas(struct ma_state *mas_detach)
-{
-	struct vm_area_struct *vma;
-
-	mas_set(mas_detach, 0);
-	mas_for_each(mas_detach, vma, ULONG_MAX)
-		vma_mark_detached(vma, false);
-
-	__mt_destroy(mas_detach->tree);
-}
-
-/*
- * vms_abort_munmap_vmas() - Undo as much as possible from an aborted munmap()
- * operation.
- * @vms: The vma unmap structure
- * @mas_detach: The maple state with the detached maple tree
- *
- * Reattach any detached vmas, free up the maple tree used to track the vmas.
- * If that's not possible because the ptes are cleared (and vm_ops->closed() may
- * have been called), then a NULL is written over the vmas and the vmas are
- * removed (munmap() completed).
- */
-static inline void vms_abort_munmap_vmas(struct vma_munmap_struct *vms,
-		struct ma_state *mas_detach)
-{
-	struct ma_state *mas = &vms->vmi->mas;
-	if (!vms->nr_pages)
-		return;
-
-	if (vms->clear_ptes)
-		return reattach_vmas(mas_detach);
-
-	/*
-	 * Aborting cannot just call the vm_ops open() because they are often
-	 * not symmetrical and state data has been lost.  Resort to the old
-	 * failure method of leaving a gap where the MAP_FIXED mapping failed.
-	 */
-	mas_set_range(mas, vms->start, vms->end - 1);
-	mas_store_gfp(mas, NULL, GFP_KERNEL|__GFP_NOFAIL);
-	/* Clean up the insertion of the unfortunate gap */
-	vms_complete_munmap_vmas(vms, mas_detach);
-}
-
 int
 do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
 		    struct mm_struct *mm, unsigned long start,
@@ -336,6 +243,10 @@ bool vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot);
 int mm_take_all_locks(struct mm_struct *mm);
 void mm_drop_all_locks(struct mm_struct *mm);
 
+unsigned long __mmap_region(struct file *file, unsigned long addr,
+		unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
+		struct list_head *uf);
+
 static inline bool vma_wants_manual_pte_write_upgrade(struct vm_area_struct *vma)
 {
 	/*