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Commit f67d9b15 authored by Bob Liu's avatar Bob Liu Committed by Linus Torvalds
Browse files

nommu: add page alignment to mmap 



Currently on nommu arch mmap(),mremap() and munmap() doesn't do
page_align() which isn't consist with mmu arch and cause some issues.

First, some drivers' mmap() function depends on vma->vm_end - vma->start
is page aligned which is true on mmu arch but not on nommu.  eg: uvc
camera driver.

Second munmap() may return -EINVAL[split file] error in cases when end is
not page aligned(passed into from userspace) but vma->vm_end is aligned
dure to split or driver's mmap() ops.

Add page alignment to fix those issues.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: default avatarBob Liu <lliubbo@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Greg Ungerer <gerg@snapgear.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent eb709b0d

mm/nommu.c

+14 −9
Original line number Diff line number Diff line
@@ -1124,7 +1124,7 @@ static int do_mmap_private(struct vm_area_struct *vma, 
			   unsigned long capabilities)

{

	struct page *pages;

	unsigned long total, point, n, rlen;

	unsigned long total, point, n;

	void *base;

	int ret, order;
@@ -1148,13 +1148,12 @@ static int do_mmap_private(struct vm_area_struct *vma, 
		 * make a private copy of the data and map that instead */

	}



	rlen = PAGE_ALIGN(len);



	/* allocate some memory to hold the mapping

	 * - note that this may not return a page-aligned address if the object

	 *   we're allocating is smaller than a page

	 */

	order = get_order(rlen);

	order = get_order(len);

	kdebug("alloc order %d for %lx", order, len);



	pages = alloc_pages(GFP_KERNEL, order);
@@ -1164,7 +1163,7 @@ static int do_mmap_private(struct vm_area_struct *vma, 
	total = 1 << order;

	atomic_long_add(total, &mmap_pages_allocated);



	point = rlen >> PAGE_SHIFT;

	point = len >> PAGE_SHIFT;



	/* we allocated a power-of-2 sized page set, so we may want to trim off

	 * the excess */
@@ -1186,7 +1185,7 @@ static int do_mmap_private(struct vm_area_struct *vma, 
	base = page_address(pages);

	region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;

	region->vm_start = (unsigned long) base;

	region->vm_end   = region->vm_start + rlen;

	region->vm_end   = region->vm_start + len;

	region->vm_top   = region->vm_start + (total << PAGE_SHIFT);



	vma->vm_start = region->vm_start;
@@ -1202,15 +1201,15 @@ static int do_mmap_private(struct vm_area_struct *vma, 


		old_fs = get_fs();

		set_fs(KERNEL_DS);

		ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos);

		ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);

		set_fs(old_fs);



		if (ret < 0)

			goto error_free;



		/* clear the last little bit */

		if (ret < rlen)

			memset(base + ret, 0, rlen - ret);

		if (ret < len)

			memset(base + ret, 0, len - ret);



	}
@@ -1259,6 +1258,7 @@ unsigned long do_mmap_pgoff(struct file *file, 


	/* we ignore the address hint */

	addr = 0;

	len = PAGE_ALIGN(len);



	/* we've determined that we can make the mapping, now translate what we

	 * now know into VMA flags */
@@ -1635,14 +1635,17 @@ static int shrink_vma(struct mm_struct *mm, 
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)

{

	struct vm_area_struct *vma;

	unsigned long end = start + len;

	unsigned long end;

	int ret;



	kenter(",%lx,%zx", start, len);



	len = PAGE_ALIGN(len);

	if (len == 0)

		return -EINVAL;



	end = start + len;



	/* find the first potentially overlapping VMA */

	vma = find_vma(mm, start);

	if (!vma) {
@@ -1762,6 +1765,8 @@ unsigned long do_mremap(unsigned long addr, 
	struct vm_area_struct *vma;



	/* insanity checks first */

	old_len = PAGE_ALIGN(old_len);

	new_len = PAGE_ALIGN(new_len);

	if (old_len == 0 || new_len == 0)

		return (unsigned long) -EINVAL;