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

From: "Hans J. Koch" <[email-masked]>
Date: Fri, 14 Oct 2011 20:46:36 +0200

On Fri, Oct 14, 2011 at 12:36:33PM -0600, Greg KH wrote:
> On Fri, Oct 14, 2011 at 08:31:45PM +0200, Hans J. Koch wrote:
> > 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
> 
> Care to send it as an email?  I can apply it easier that way as I have
> limited internet access while on the road.
> 
> greg k-h

>>From b00f4ca33322a48928624ae3c34dc5fe9d2f40ff Mon Sep 17 00:00:00 2001
From: Kai Jiang <[email-masked]>
Date: Fri, 14 Oct 2011 20:04:43 +0200
Subject: [PATCH] uio: Support physical addresses >32 bits on 32-bit systems

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]>
---
 Documentation/DocBook/uio-howto.tmpl |    2 +-
 drivers/uio/uio.c                    |    7 +++----
 include/linux/uio_driver.h           |    7 +++++--
 3 files changed, 9 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 d2efe82..c0626ea 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 +634,7 @@ 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 *)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 665517c..fd99ff9 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
@@ -31,7 +34,7 @@ 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;
-- 
1.7.6.3