Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ecc1a899 authored by Al Viro's avatar Al Viro
Browse files

do_mremap() untangling, part 2 



Take the MREMAP_FIXED into a separate helper, simplify the living
hell out of conditions in both cases.

Acked-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
Acked-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 54f5de70

mm/mremap.c

+72 −48
Original line number Diff line number Diff line
@@ -313,6 +313,59 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr, 
	return ERR_PTR(-EAGAIN);

}



static unsigned long mremap_to(unsigned long addr,

	unsigned long old_len, unsigned long new_addr,

	unsigned long new_len)

{

	struct mm_struct *mm = current->mm;

	struct vm_area_struct *vma;

	unsigned long ret = -EINVAL;

	unsigned long charged = 0;



	if (new_addr & ~PAGE_MASK)

		goto out;



	if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)

		goto out;



	/* Check if the location we're moving into overlaps the

	 * old location at all, and fail if it does.

	 */

	if ((new_addr <= addr) && (new_addr+new_len) > addr)

		goto out;



	if ((addr <= new_addr) && (addr+old_len) > new_addr)

		goto out;



	ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);

	if (ret)

		goto out;



	ret = do_munmap(mm, new_addr, new_len);

	if (ret)

		goto out;



	if (old_len >= new_len) {

		ret = do_munmap(mm, addr+new_len, old_len - new_len);

		if (ret && old_len != new_len)

			goto out;

		old_len = new_len;

	}



	vma = vma_to_resize(addr, old_len, new_len, &charged);

	if (IS_ERR(vma)) {

		ret = PTR_ERR(vma);

		goto out;

	}



	ret = move_vma(vma, addr, old_len, new_len, new_addr);

	if (ret & ~PAGE_MASK)

		vm_unacct_memory(charged);



out:

	return ret;

}



/*

 * Expand (or shrink) an existing mapping, potentially moving it at the

 * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
@@ -346,31 +399,9 @@ unsigned long do_mremap(unsigned long addr, 
	if (!new_len)

		goto out;



	/* new_addr is only valid if MREMAP_FIXED is specified */

	if (flags & MREMAP_FIXED) {

		if (new_addr & ~PAGE_MASK)

			goto out;

		if (!(flags & MREMAP_MAYMOVE))

			goto out;



		if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len)

			goto out;



		/* Check if the location we're moving into overlaps the

		 * old location at all, and fail if it does.

		 */

		if ((new_addr <= addr) && (new_addr+new_len) > addr)

			goto out;



		if ((addr <= new_addr) && (addr+old_len) > new_addr)

			goto out;



		ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);

		if (ret)

			goto out;



		ret = do_munmap(mm, new_addr, new_len);

		if (ret)

		if (flags & MREMAP_MAYMOVE)

			ret = mremap_to(addr, old_len, new_addr, new_len);

		goto out;

	}
@@ -384,13 +415,11 @@ unsigned long do_mremap(unsigned long addr, 
		if (ret && old_len != new_len)

			goto out;

		ret = addr;

		if (!(flags & MREMAP_FIXED) || (new_addr == addr))

		goto out;

		old_len = new_len;

	}



	/*

	 * Ok, we need to grow..  or relocate.

	 * Ok, we need to grow..

	 */

	vma = vma_to_resize(addr, old_len, new_len, &charged);

	if (IS_ERR(vma)) {
@@ -399,11 +428,8 @@ unsigned long do_mremap(unsigned long addr, 
	}



	/* old_len exactly to the end of the area..

	 * And we're not relocating the area.

	 */

	if (old_len == vma->vm_end - addr &&

	    !((flags & MREMAP_FIXED) && (addr != new_addr)) &&

	    (old_len != new_len || !(flags & MREMAP_MAYMOVE))) {

	if (old_len == vma->vm_end - addr) {

		unsigned long max_addr = TASK_SIZE;

		if (vma->vm_next)

			max_addr = vma->vm_next->vm_start;
@@ -432,7 +458,6 @@ unsigned long do_mremap(unsigned long addr, 
	 */

	ret = -ENOMEM;

	if (flags & MREMAP_MAYMOVE) {

		if (!(flags & MREMAP_FIXED)) {

		unsigned long map_flags = 0;

		if (vma->vm_flags & VM_MAYSHARE)

			map_flags |= MAP_SHARED;
@@ -447,7 +472,6 @@ unsigned long do_mremap(unsigned long addr, 
		ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1);

		if (ret)

			goto out;

		}

		ret = move_vma(vma, addr, old_len, new_len, new_addr);

	}

out: