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nommu: add page alignment to mmap

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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: Bob 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Bob Liu 2011-05-24 17:12:56 -07:00 committed by Linus Torvalds
parent eb709b0d06
commit f67d9b1576
1 changed files with 14 additions and 9 deletions
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23
mm/nommu.c
View file

@ -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;