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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

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?

> 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?

> 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?

> 
> 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);



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