nommu: convert nommu to using the vma iterator

Gain type safety in nommu by using the vma_iterator and not the maple tree
directly.

Link: https://lkml.kernel.org/r/20230120162650.984577-28-Liam.Howlett@oracle.com
Signed-off-by: Liam R.  Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/nommu.c b/mm/nommu.c
index 0481922fe66e4c440b5382441510bf2e5ff57ece..7a52a7c37009905ff60f7dde4d3654a3acfea5db 100644 (file)
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -544,19 +544,6 @@ static void put_nommu_region(struct vm_region *region)
        __put_nommu_region(region);
 }
 
-void vma_mas_store(struct vm_area_struct *vma, struct ma_state *mas)
-{
-       mas_set_range(mas, vma->vm_start, vma->vm_end - 1);
-       mas_store_prealloc(mas, vma);
-}
-
-void vma_mas_remove(struct vm_area_struct *vma, struct ma_state *mas)
-{
-       mas->index = vma->vm_start;
-       mas->last = vma->vm_end - 1;
-       mas_store_prealloc(mas, NULL);
-}
-
 static void setup_vma_to_mm(struct vm_area_struct *vma, struct mm_struct *mm)
 {
        vma->vm_mm = mm;
@@ -574,13 +561,13 @@ static void setup_vma_to_mm(struct vm_area_struct *vma, struct mm_struct *mm)
 }
 
 /*
- * mas_add_vma_to_mm() - Maple state variant of add_mas_to_mm().
- * @mas: The maple state with preallocations.
+ * vmi_add_vma_to_mm() - VMA Iterator variant of add_vmi_to_mm().
+ * @vmi: The VMA iterator
  * @mm: The mm_struct
  * @vma: The vma to add
  *
  */
-static void mas_add_vma_to_mm(struct ma_state *mas, struct mm_struct *mm,
+static void vmi_add_vma_to_mm(struct vma_iterator *vmi, struct mm_struct *mm,
                              struct vm_area_struct *vma)
 {
        BUG_ON(!vma->vm_region);
@@ -589,7 +576,7 @@ static void mas_add_vma_to_mm(struct ma_state *mas, struct mm_struct *mm,
        mm->map_count++;
 
        /* add the VMA to the tree */
-       vma_mas_store(vma, mas);
+       vma_iter_store(vmi, vma);
 }
 
 /*
@@ -600,14 +587,14 @@ static void mas_add_vma_to_mm(struct ma_state *mas, struct mm_struct *mm,
  */
 static int add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 {
-       MA_STATE(mas, &mm->mm_mt, vma->vm_start, vma->vm_end);
+       VMA_ITERATOR(vmi, mm, vma->vm_start);
 
-       if (mas_preallocate(&mas, GFP_KERNEL)) {
+       if (vma_iter_prealloc(&vmi)) {
                pr_warn("Allocation of vma tree for process %d failed\n",
                       current->pid);
                return -ENOMEM;
        }
-       mas_add_vma_to_mm(&mas, mm, vma);
+       vmi_add_vma_to_mm(&vmi, mm, vma);
        return 0;
 }
 
@@ -626,14 +613,15 @@ static void cleanup_vma_from_mm(struct vm_area_struct *vma)
                i_mmap_unlock_write(mapping);
        }
 }
+
 /*
  * delete a VMA from its owning mm_struct and address space
  */
 static int delete_vma_from_mm(struct vm_area_struct *vma)
 {
-       MA_STATE(mas, &vma->vm_mm->mm_mt, 0, 0);
+       VMA_ITERATOR(vmi, vma->vm_mm, vma->vm_start);
 
-       if (mas_preallocate(&mas, GFP_KERNEL)) {
+       if (vma_iter_prealloc(&vmi)) {
                pr_warn("Allocation of vma tree for process %d failed\n",
                       current->pid);
                return -ENOMEM;
@@ -641,10 +629,9 @@ static int delete_vma_from_mm(struct vm_area_struct *vma)
        cleanup_vma_from_mm(vma);
 
        /* remove from the MM's tree and list */
-       vma_mas_remove(vma, &mas);
+       vma_iter_clear(&vmi, vma->vm_start, vma->vm_end);
        return 0;
 }
-
 /*
  * destroy a VMA record
  */
@@ -675,9 +662,9 @@ EXPORT_SYMBOL(find_vma_intersection);
  */
 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 {
-       MA_STATE(mas, &mm->mm_mt, addr, addr);
+       VMA_ITERATOR(vmi, mm, addr);
 
-       return mas_walk(&mas);
+       return vma_iter_load(&vmi);
 }
 EXPORT_SYMBOL(find_vma);
 
@@ -709,9 +696,9 @@ static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 {
        struct vm_area_struct *vma;
        unsigned long end = addr + len;
-       MA_STATE(mas, &mm->mm_mt, addr, addr);
+       VMA_ITERATOR(vmi, mm, addr);
 
-       vma = mas_walk(&mas);
+       vma = vma_iter_load(&vmi);
        if (!vma)
                return NULL;
        if (vma->vm_start != addr)
@@ -1062,7 +1049,7 @@ unsigned long do_mmap(struct file *file,
        vm_flags_t vm_flags;
        unsigned long capabilities, result;
        int ret;
-       MA_STATE(mas, &current->mm->mm_mt, 0, 0);
+       VMA_ITERATOR(vmi, current->mm, 0);
 
        *populate = 0;
 
@@ -1091,8 +1078,8 @@ unsigned long do_mmap(struct file *file,
        if (!vma)
                goto error_getting_vma;
 
-       if (mas_preallocate(&mas, GFP_KERNEL))
-               goto error_maple_preallocate;
+       if (vma_iter_prealloc(&vmi))
+               goto error_vma_iter_prealloc;
 
        region->vm_usage = 1;
        region->vm_flags = vm_flags;
@@ -1234,7 +1221,7 @@ unsigned long do_mmap(struct file *file,
        current->mm->total_vm += len >> PAGE_SHIFT;
 
 share:
-       mas_add_vma_to_mm(&mas, current->mm, vma);
+       vmi_add_vma_to_mm(&vmi, current->mm, vma);
 
        /* we flush the region from the icache only when the first executable
         * mapping of it is made  */
@@ -1250,7 +1237,7 @@ share:
 error_just_free:
        up_write(&nommu_region_sem);
 error:
-       mas_destroy(&mas);
+       vma_iter_free(&vmi);
        if (region->vm_file)
                fput(region->vm_file);
        kmem_cache_free(vm_region_jar, region);
@@ -1278,7 +1265,7 @@ error_getting_region:
        show_free_areas(0, NULL);
        return -ENOMEM;
 
-error_maple_preallocate:
+error_vma_iter_prealloc:
        kmem_cache_free(vm_region_jar, region);
        vm_area_free(vma);
        pr_warn("Allocation of vma tree for process %d failed\n", current->pid);
@@ -1344,20 +1331,18 @@ SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
  * split a vma into two pieces at address 'addr', a new vma is allocated either
  * for the first part or the tail.
  */
-int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
-             unsigned long addr, int new_below)
+int vmi_split_vma(struct vma_iterator *vmi, struct mm_struct *mm,
+                 struct vm_area_struct *vma, unsigned long addr, int new_below)
 {
        struct vm_area_struct *new;
        struct vm_region *region;
        unsigned long npages;
-       MA_STATE(mas, &mm->mm_mt, vma->vm_start, vma->vm_end);
 
        /* we're only permitted to split anonymous regions (these should have
         * only a single usage on the region) */
        if (vma->vm_file)
                return -ENOMEM;
 
-       mm = vma->vm_mm;
        if (mm->map_count >= sysctl_max_map_count)
                return -ENOMEM;
 
@@ -1369,10 +1354,10 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
        if (!new)
                goto err_vma_dup;
 
-       if (mas_preallocate(&mas, GFP_KERNEL)) {
+       if (vma_iter_prealloc(vmi)) {
                pr_warn("Allocation of vma tree for process %d failed\n",
                        current->pid);
-               goto err_mas_preallocate;
+               goto err_vmi_preallocate;
        }
 
        /* most fields are the same, copy all, and then fixup */
@@ -1406,13 +1391,11 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
 
        setup_vma_to_mm(vma, mm);
        setup_vma_to_mm(new, mm);
-       mas_set_range(&mas, vma->vm_start, vma->vm_end - 1);
-       mas_store(&mas, vma);
-       vma_mas_store(new, &mas);
+       vma_iter_store(vmi, new);
        mm->map_count++;
        return 0;
 
-err_mas_preallocate:
+err_vmi_preallocate:
        vm_area_free(new);
 err_vma_dup:
        kmem_cache_free(vm_region_jar, region);
@@ -1466,7 +1449,7 @@ static int shrink_vma(struct mm_struct *mm,
  */
 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf)
 {
-       MA_STATE(mas, &mm->mm_mt, start, start);
+       VMA_ITERATOR(vmi, mm, start);
        struct vm_area_struct *vma;
        unsigned long end;
        int ret = 0;
@@ -1478,7 +1461,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list
        end = start + len;
 
        /* find the first potentially overlapping VMA */
-       vma = mas_find(&mas, end - 1);
+       vma = vma_find(&vmi, end);
        if (!vma) {
                static int limit;
                if (limit < 5) {
@@ -1497,7 +1480,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list
                                return -EINVAL;
                        if (end == vma->vm_end)
                                goto erase_whole_vma;
-                       vma = mas_next(&mas, end - 1);
+                       vma = vma_find(&vmi, end);
                } while (vma);
                return -EINVAL;
        } else {
@@ -1511,7 +1494,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list
                if (end != vma->vm_end && offset_in_page(end))
                        return -EINVAL;
                if (start != vma->vm_start && end != vma->vm_end) {
-                       ret = split_vma(mm, vma, start, 1);
+                       ret = vmi_split_vma(&vmi, mm, vma, start, 1);
                        if (ret < 0)
                                return ret;
                }