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

[Olaf Hering <olaf@aepfle.de>]

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;