[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH V1 11/29] xen/dts: Check "reg" property length in process_multiboot_node



On 09/06/2013 05:40 PM, Ian Campbell wrote:
On Wed, 2013-08-28 at 15:47 +0100, Julien Grall wrote:
When the device tree compiler (dtc) can't find right #address-cells
and #size-cells, it will assume the encoding is 1 for each.

Without inserting them into the DTB I suppose?

Yes. I have noticed that the encoding is not 1 for each but
"If missing, a client program should assume a default value of 2 for #address-cells, and a value of 1 for #size-cells." (ePAR 2.3.5)

dtc will warns with the following messages:
Warning (reg_format): "reg" property in /chosen/modules/module@0 has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1) Warning (avoid_default_addr_size): Relying on default #address-cells value for /chosen/modules/module@0 Warning (avoid_default_addr_size): Relying on default #size-cells value for /chosen/modules/module@0

As multiboot node are inside the /chosen, dtc will asume the previous values

"assume"

if the both property are not correct set.

"the both property" => "both properties" and "correctly"

By "previous values" do you mean the values set in the (grand)parent
node?

Yes. I will update the comment.

During boot, Xen will browse the fdt and store the nearest #address-cells
and #size-cells value. If the size of "reg" is smaller, Xen can retrieve
wrong range.

How come Xen can find a suitable #address-cells but dtc cannot? Are we
not handling them correctly perhaps?

So we have two issues:
  1) Xen doesn't check the length of the reg property (this patch)
  2) Default value for #address-cells and #size-cells are wrong


Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
---
  xen/common/device_tree.c |    6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index 9568250..7295f34 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -467,10 +467,14 @@ static void __init process_multiboot_node(const void 
*fdt, int node,

      mod = &early_info.modules.module[nr];

-    prop = fdt_get_property(fdt, node, "reg", NULL);
+    prop = fdt_get_property(fdt, node, "reg", &len);
      if ( !prop )
          early_panic("node %s missing `reg' property\n", name);

+    if ( len < dt_cells_to_size(address_cells + size_cells) )
+        early_panic("fdt: node `%s': `reg` property length is too short\n",
+                    name);
+
      cell = (const u32 *)prop->data;
      device_tree_get_reg(&cell, address_cells, size_cells,
                          &mod->start, &mod->size);




--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.