Subject: Re: [PATCH] uio: Support 36-bit physical addresses on 32-bit systems

From: "Hans J. Koch" <[email-masked]>
Date: Fri, 14 Oct 2011 20:31:45 +0200

On Thu, Oct 13, 2011 at 10:50:58AM -0500, Kumar Gala wrote:
> From: Kai Jiang <[email-masked]>
> 
> To support >32-bit physical addresses for UIO_MEM_PHYS type we need to
> extend the width of 'addr' in struct uio_mem.  Numerous platforms like
> embedded PPC, ARM, and X86 have support for systems with larger physical
> address than logical.
> 
> Since 'addr' may contain a physical, logical, or virtual address the
> easiest solution is to just change the type to 'phys_addr_t' which
> should always be greater than or equal to the sizeof(void *) such that
> it can properly hold any of the address types.
> 
> For physical address we can support up to a 44-bit physical address on a
> typical 32-bit system as we utilize remap_pfn_range() for the mapping of
> the memory region and pfn's are represnted by shifting the address by
> the page size (typically 4k).
> 
> Signed-off-by: Kai Jiang <[email-masked]>
> Signed-off-by: Minghuan Lian <[email-masked]>
> Signed-off-by: Kumar Gala <[email-masked]>

Signed-off-by: "Hans J. Koch" <[email-masked]>

That looks good to me. There's an unnecessary cast (see below), but I fixed that
on the way.

Greg, please pull this from branch uio-for-gregkh from

git://hansjkoch.de/git/linux-hjk

Thanks,
Hans

> ---
> v3:
> * Updated commit message to be correct w/regards to code
> * Updated comment about addr field in uio_mem
> v2:
> * Use phys_addr_t instead of 'unsigned long long'
> * Updated DocBook detail in uio-howto.tmpl
> 
>  Documentation/DocBook/uio-howto.tmpl |    2 +-
>  drivers/uio/uio.c                    |    8 ++++----
>  include/linux/uio_driver.h           |    7 +++++--
>  3 files changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/DocBook/uio-howto.tmpl b/Documentation/DocBook/uio-howto.tmpl
> index 7c4b514d..54883de 100644
> --- a/Documentation/DocBook/uio-howto.tmpl
> +++ b/Documentation/DocBook/uio-howto.tmpl
> @@ -529,7 +529,7 @@ memory (e.g. allocated with <function>kmalloc()</function>). There's also
>  </para></listitem>
>  
>  <listitem><para>
> -<varname>unsigned long addr</varname>: Required if the mapping is used.
> +<varname>phys_addr_t addr</varname>: Required if the mapping is used.
>  Fill in the address of your memory block. This address is the one that
>  appears in sysfs.
>  </para></listitem>
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index 88f4444..43b7096 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -69,7 +69,7 @@ static ssize_t map_name_show(struct uio_mem *mem, char *buf)
>  
>  static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
>  {
> -	return sprintf(buf, "0x%lx\n", mem->addr);
> +	return sprintf(buf, "0x%llx\n", (unsigned long long)mem->addr);
>  }
>  
>  static ssize_t map_size_show(struct uio_mem *mem, char *buf)
> @@ -79,7 +79,7 @@ static ssize_t map_size_show(struct uio_mem *mem, char *buf)
>  
>  static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
>  {
> -	return sprintf(buf, "0x%lx\n", mem->addr & ~PAGE_MASK);
> +	return sprintf(buf, "0x%llx\n", (unsigned long long)mem->addr & ~PAGE_MASK);
>  }
>  
>  struct map_sysfs_entry {
> @@ -634,8 +634,8 @@ static int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
>  	if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
>  		page = virt_to_page(idev->info->mem[mi].addr + offset);
>  	else
> -		page = vmalloc_to_page((void *)idev->info->mem[mi].addr
> -							+ offset);
> +		page = vmalloc_to_page((void *)(unsigned long)

(void *) is enough, the (unsigned long) is not needed.

> +				idev->info->mem[mi].addr + offset);
>  	get_page(page);
>  	vmf->page = page;
>  	return 0;
> diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
> index 4c618cd..ad16aa9 100644
> --- a/include/linux/uio_driver.h
> +++ b/include/linux/uio_driver.h
> @@ -23,7 +23,10 @@ struct uio_map;
>  /**
>   * struct uio_mem - description of a UIO memory region
>   * @name:		name of the memory region for identification
> - * @addr:		address of the device's memory
> + * @addr:		address of the device's memory (phys_addr is used since
> + * 			addr can be logical, virtual, or physical & phys_addr_t
> + * 			should always be large enough to handle any of the
> + * 			address types)
>   * @size:		size of IO
>   * @memtype:		type of memory addr points to
>   * @internal_addr:	ioremap-ped version of addr, for driver internal use
> @@ -32,7 +35,7 @@ struct uio_map;
>   */
>  struct uio_mem {
>  	const char		*name;
> -	unsigned long		addr;
> +	phys_addr_t		addr;
>  	unsigned long		size;
>  	int			memtype;
>  	void __iomem		*internal_addr;
> -- 
> 1.7.3.4
> 
>