2005-09-22 11:56:57

by Keir Fraser

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

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)) {

2005-09-22 13:57:59

by Bob Picco

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

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 <[email protected]>
>

> 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