On 07/21/2010 03:50 PM, Konrad Rzeszutek Wilk wrote:
>> The code path is fb_mmap with a NULL fbops->fb_mmap, so it just
>> delegates to the default code. Specifically, io_remap_pfn_range is where
>> the bad mapping is requested.
>>
>> I have a patch that fixes the issue, but I'm not sure under what
>> conditions the _PAGE_IOMAP bit needs to be set.
>
> Oh wow. That easy, eh?
>
>> --- a/arch/x86/include/asm/fb.h
>> +++ b/arch/x86/include/asm/fb.h
>> @@ -10,6 +10,7 @@ static inline void fb_pgprotect
>> {
>> if (boot_cpu_data.x86 > 3)
>> pgprot_val(vma->vm_page_prot) |= _PAGE_PCD;
>> + pgprot_val(vma->vm_page_prot) |= _PAGE_IOMAP;
>> }
>>
>> #ifdef CONFIG_X86_32
>
>
> I would say this patch is more sensible as the VM_IO flag had been
> set already, it just never got propagated:
>
>
> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
> index 731fce6..187171b 100644
> --- a/drivers/video/fbmem.c
> +++ b/drivers/video/fbmem.c
> @@ -1362,6 +1362,7 @@ fb_mmap(struct file *file, struct vm_area_struct * vma)
> vma->vm_pgoff = off >> PAGE_SHIFT;
> /* This is an IO map - tell maydump to skip this VMA */
> vma->vm_flags |= VM_IO | VM_RESERVED;
> + vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> fb_pgprotect(file, vma, off);
> if (io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
> vma->vm_end - vma->vm_start, vma->vm_page_prot))
>
>
> If that fixes your problem, are you OK with me sticking a Signed-off-by:
> from you on this patch?
>
Yep, your version also fixes the problem, and I agree it's more
sensible. I'm OK with signing off on that patch.
--
Daniel De Graaf
National Security Agency
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