[PATCH] Fix mmap() of /dev/hpet

[PATCH] Fix mmap() of /dev/hpet

[Keir Fraser]

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The address passed to io_remap_pfn_range() in hpet_mmap() does not
need to be converted using __pa(): it is already a physical
address. This bug was found and the patch suggested by Clay Harris. 

I introduced this particular bug when making io_remap_pfn_range
changes a few months ago. In fact mmap()ing /dev/hpet has *never*
previously worked: before my changes __pa() was being executed on an
ioremap()ed virtual address, which is also invalid.

Signed-off-by: Keir Fraser <keir@xensource.com>


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diff -urpP linux-2.6.14-rc2.old/drivers/char/hpet.c linux-2.6.14-rc2.new/drivers/char/hpet.c
--- linux-2.6.14-rc2.old/drivers/char/hpet.c	2005-09-22 12:47:00.773424663 +0100
+++ linux-2.6.14-rc2.new/drivers/char/hpet.c	2005-09-22 12:47:18.216928551 +0100
@@ -273,7 +273,6 @@ static int hpet_mmap(struct file *file, 
 
 	vma->vm_flags |= VM_IO;
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-	addr = __pa(addr);
 
 	if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT,
 					PAGE_SIZE, vma->vm_page_prot)) {

Re: [PATCH] Fix mmap() of /dev/hpet

[Bob Picco]

Keir Fraser wrote:	[Thu Sep 22 2005, 07:56:50AM EDT]
> The address passed to io_remap_pfn_range() in hpet_mmap() does not
> need to be converted using __pa(): it is already a physical
> address. This bug was found and the patch suggested by Clay Harris. 
> 
> I introduced this particular bug when making io_remap_pfn_range
> changes a few months ago. In fact mmap()ing /dev/hpet has *never*
> previously worked: before my changes __pa() was being executed on an
> ioremap()ed virtual address, which is also invalid.
> 
> Signed-off-by: Keir Fraser <keir@xensource.com>
> 

> diff -urpP linux-2.6.14-rc2.old/drivers/char/hpet.c linux-2.6.14-rc2.new/drivers/char/hpet.c
> --- linux-2.6.14-rc2.old/drivers/char/hpet.c	2005-09-22 12:47:00.773424663 +0100
> +++ linux-2.6.14-rc2.new/drivers/char/hpet.c	2005-09-22 12:47:18.216928551 +0100
> @@ -273,7 +273,6 @@ static int hpet_mmap(struct file *file, 
>  
>  	vma->vm_flags |= VM_IO;
>  	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> -	addr = __pa(addr);
>  
>  	if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT,
>  					PAGE_SIZE, vma->vm_page_prot)) {
Keir:

Well it looks definitely wrong. I wonder how my mmap test ever succeeded. 

thanks,

bob