On Thu, Jan 09, 2025 at 09:27:00PM +0800, Zijun Hu wrote:
> From: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
>
> According to DT spec, size of property 'alignment' is based on parent
> node’s #size-cells property.
>
> But __reserved_mem_alloc_size() wrongly uses @dt_root_addr_cells to get
> the property obviously.
>
> Fix by using @dt_root_size_cells instead of @dt_root_addr_cells.
I wonder if changing this might break someone. It's been this way for
a long time. It might be better to change the spec or just read
'alignment' as whatever size it happens to be (len / 4). It's not really
the kernel's job to validate the DT. We should first have some
validation in place to *know* if there are any current .dts files that
would break. That would probably be easier to implement in dtc than
dtschema. Cases of #address-cells != #size-cells should be pretty rare,
but that was the default for OpenFirmware.
As the alignment is the base address alignment, it can be argued that
"#address-cells" makes more sense to use than "#size-cells". So maybe
the spec was a copy-n-paste error.
>
> Fixes: 3f0c82066448 ("drivers: of: add initialization code for dynamic reserved memory")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
> ---
> drivers/of/of_reserved_mem.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 45517b9e57b1add36bdf2109227ebbf7df631a66..d2753756d7c30adcbd52f57338e281c16d821488 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -409,12 +409,12 @@ static int __init __reserved_mem_alloc_size(unsigned long node, const char *unam
>
> prop = of_get_flat_dt_prop(node, "alignment", &len);
> if (prop) {
> - if (len != dt_root_addr_cells * sizeof(__be32)) {
> + if (len != dt_root_size_cells * sizeof(__be32)) {
> pr_err("invalid alignment property in '%s' node.\n",
> uname);
> return -EINVAL;
> }
> - align = dt_mem_next_cell(dt_root_addr_cells, &prop);
> + align = dt_mem_next_cell(dt_root_size_cells, &prop);
> }
>
> nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
>
> --
> 2.34.1
>
