Commit 2286a691 authored by Liam R. Howlett's avatar Liam R. Howlett Committed by Andrew Morton
Browse files

mm: change mprotect_fixup to vma iterator 

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

Link: https://lkml.kernel.org/r/20230120162650.984577-18-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 11a9b902

fs/exec.c

+4 −1
Original line number Diff line number Diff line
@@ -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;



#ifdef CONFIG_STACK_GROWSUP

	/* Limit stack size */
@@ -812,8 +813,10 @@ int setup_arg_pages(struct linux_binprm *bprm, 
	vm_flags |= mm->def_flags;

	vm_flags |= VM_STACK_INCOMPLETE_SETUP;



	vma_iter_init(&vmi, mm, vma->vm_start);



	tlb_gather_mmu(&tlb, mm);

	ret = mprotect_fixup(&tlb, vma, &prev, vma->vm_start, vma->vm_end,

	ret = mprotect_fixup(&vmi, &tlb, vma, &prev, vma->vm_start, vma->vm_end,

			vm_flags);

	tlb_finish_mmu(&tlb);

include/linux/mm.h

+3 −3
Original line number Diff line number Diff line
@@ -2197,9 +2197,9 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, 
extern long change_protection(struct mmu_gather *tlb,

			      struct vm_area_struct *vma, unsigned long start,

			      unsigned long end, unsigned long cp_flags);

extern 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);

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);



/*

 * doesn't attempt to fault and will return short.

mm/mprotect.c

+22 −25
Original line number Diff line number Diff line
@@ -585,9 +585,9 @@ static const struct mm_walk_ops prot_none_walk_ops = { 
};



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 = vma->vm_mm;

	unsigned long oldflags = vma->vm_flags;
@@ -642,7 +642,7 @@ mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma, 
	 * First try to merge with previous and/or next vma.

	 */

	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);

	*pprev = vma_merge(mm, *pprev, start, end, newflags,

	*pprev = 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) {
@@ -654,13 +654,13 @@ mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma, 
	*pprev = vma;



	if (start != vma->vm_start) {

		error = split_vma(mm, vma, start, 1);

		error = vmi_split_vma(vmi, mm, vma, start, 1);

		if (error)

			goto fail;

	}



	if (end != vma->vm_end) {

		error = split_vma(mm, vma, end, 0);

		error = vmi_split_vma(vmi, mm, vma, end, 0);

		if (error)

			goto fail;

	}
@@ -709,7 +709,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len, 
	const bool rier = (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;



	start = untagged_addr(start);
@@ -741,8 +741,8 @@ static int do_mprotect_pkey(unsigned long start, size_t len, 
	if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))

		goto out;



	mas_set(&mas, start);

	vma = mas_find(&mas, ULONG_MAX);

	vma_iter_init(&vmi, current->mm, start);

	vma = vma_find(&vmi, end);

	error = -ENOMEM;

	if (!vma)

		goto out;
@@ -765,18 +765,22 @@ static int do_mprotect_pkey(unsigned long start, size_t len, 
		}

	}



	prev = vma_prev(&vmi);

	if (start > vma->vm_start)

		prev = vma;

	else

		prev = mas_prev(&mas, 0);



	tlb_gather_mmu(&tlb, current->mm);

	for (nstart = start ; ; ) {

	nstart = start;

	tmp = vma->vm_start;

	for_each_vma_range(vmi, vma, end) {

		unsigned long mask_off_old_flags;

		unsigned long newflags;

		int new_vma_pkey;



		/* Here we know that vma->vm_start <= nstart < vma->vm_end. */

		if (vma->vm_start != tmp) {

			error = -ENOMEM;

			break;

		}



		/* Does the application expect PROT_READ to imply PROT_EXEC */

		if (rier && (vma->vm_flags & VM_MAYEXEC))
@@ -824,25 +828,18 @@ static int do_mprotect_pkey(unsigned long start, size_t len, 
				break;

		}



		error = mprotect_fixup(&tlb, vma, &prev, nstart, tmp, newflags);

		error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags);

		if (error)

			break;



		nstart = tmp;



		if (nstart < prev->vm_end)

			nstart = prev->vm_end;

		if (nstart >= end)

			break;



		vma = find_vma(current->mm, prev->vm_end);

		if (!vma || vma->vm_start != nstart) {

			error = -ENOMEM;

			break;

		}

		prot = reqprot;

	}

	tlb_finish_mmu(&tlb);



	if (vma_iter_end(&vmi) < end)

		error = -ENOMEM;



out:

	mmap_write_unlock(current->mm);

	return error;