Re: [PATCH] Fix mmap_kmem (was: [question] What's the difference between /dev/kmem and /dev/mem)

Olaf Hering
2005-08-15T19:33:44Z

On Sat, Aug 13, 2005 at 10:37:03AM -0700, Linus Torvalds wrote:
>
>
> On Sat, 13 Aug 2005, Arjan van de Ven wrote:
> >
> > attached is the same patch but now with Steven's change made as well
>
> Actually, the more I looked at that mmap_kmem() function, the less I liked
> it. Let's get that sucker fixed better first. It's still not wonderful,
> but at least now it tries to verify the whole _range_ of the mapping.
>
> Steven, does this "alternate mmap_kmem fix" patch work for you?
>
> Linus
> ----
> diff --git a/drivers/char/mem.c b/drivers/char/mem.c
> --- a/drivers/char/mem.c
> +++ b/drivers/char/mem.c
> @@ -261,7 +261,11 @@ static int mmap_mem(struct file * file,
>
> static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
> {
> - unsigned long long val;
> + unsigned long pfn, size;
> +
> + /* Turn a kernel-virtual address into a physical page frame */
> + pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
> +

ARCH=um doesnt like your version, but mine.

drivers/char/mem.c:267: error: invalid operands to binary <<

pfn = (__pa((u64)vma->vm_pgoff) << PAGE_SHIFT) >> PAGE_SHIFT;