VM: add "vm_mmap()" helper function
This continues the theme started with vm_brk() and vm_munmap():
vm_mmap() does the same thing as do_mmap(), but additionally does the
required VM locking.
This uninlines (and rewrites it to be clearer) do_mmap(), which sadly
duplicates it in mm/mmap.c and mm/nommu.c. But that way we don't have
to export our internal do_mmap_pgoff() function.
Some day we hopefully don't have to export do_mmap() either, if all
modular users can become the simpler vm_mmap() instead. We're actually
very close to that already, with the notable exception of the (broken)
use in i810, and a couple of stragglers in binfmt_elf.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/mmap.c b/mm/mmap.c
index 4af45f5..b38b47e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -953,7 +953,7 @@
* The caller must hold down_write(¤t->mm->mmap_sem).
*/
-unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
+static unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot,
unsigned long flags, unsigned long pgoff)
{
@@ -1089,7 +1089,32 @@
return mmap_region(file, addr, len, flags, vm_flags, pgoff);
}
-EXPORT_SYMBOL(do_mmap_pgoff);
+
+unsigned long do_mmap(struct file *file, unsigned long addr,
+ unsigned long len, unsigned long prot,
+ unsigned long flag, unsigned long offset)
+{
+ if (unlikely(offset + PAGE_ALIGN(len) < offset))
+ return -EINVAL;
+ if (unlikely(offset & ~PAGE_MASK))
+ return -EINVAL;
+ return do_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
+}
+EXPORT_SYMBOL(do_mmap);
+
+unsigned long vm_mmap(struct file *file, unsigned long addr,
+ unsigned long len, unsigned long prot,
+ unsigned long flag, unsigned long offset)
+{
+ unsigned long ret;
+ struct mm_struct *mm = current->mm;
+
+ down_write(&mm->mmap_sem);
+ ret = do_mmap(file, addr, len, prot, flag, offset);
+ up_write(&mm->mmap_sem);
+ return ret;
+}
+EXPORT_SYMBOL(vm_mmap);
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
unsigned long, prot, unsigned long, flags,