Commit 47d9644d authored by Liam R. Howlett's avatar Liam R. Howlett Committed by Andrew Morton
Browse files

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: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a27a11f9

mm/nommu.c

+31 −48
Original line number Diff line number Diff line
@@ -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 @@ unsigned long do_mmap(struct file *file, 
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 @@ unsigned long do_mmap(struct file *file, 
	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;

		}