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Subject[PATCH] uio: Support 36-bit physical addresses on 32-bit systems
From: Kai Jiang <>

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 <>
Signed-off-by: Minghuan Lian <>
Signed-off-by: Kumar Gala <>
* Updated commit message to be correct w/regards to code
* Updated comment about addr field in uio_mem
* 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

-<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.
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);
- page = vmalloc_to_page((void *)idev->info->mem[mi].addr
- + offset);
+ page = vmalloc_to_page((void *)(unsigned long)
+ idev->info->mem[mi].addr + offset);
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;

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