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: 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>

1 files changed, 14 insertions, 9 deletions

diff --git a/mm/nommu.c b/mm/nommu.c
index 92e1a47d1e52..1fd0c51b10a6 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -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;