of/flattree: Make unflatten_device_tree() safe to call from any arch
This patch makes unflatten_device_tree() safe to call from any arch
setup code with the following changes:
- Make sure initial_boot_params actually points to a device tree blob
before unflattening
- Make sure the initial_boot_params->magic field is correct
- If CONFIG_OF_FLATTREE is not set, then make unflatten_device_tree()
an empty static inline function.
This patch also adds some additional debug output to the top of
unflatten_device_tree().
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index dee4fb5..b6987bb 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -556,6 +556,21 @@
pr_debug(" -> unflatten_device_tree()\n");
+ if (!initial_boot_params) {
+ pr_debug("No device tree pointer\n");
+ return;
+ }
+
+ pr_debug("Unflattening device tree:\n");
+ pr_debug("magic: %08x\n", be32_to_cpu(initial_boot_params->magic));
+ pr_debug("size: %08x\n", be32_to_cpu(initial_boot_params->totalsize));
+ pr_debug("version: %08x\n", be32_to_cpu(initial_boot_params->version));
+
+ if (be32_to_cpu(initial_boot_params->magic) != OF_DT_HEADER) {
+ pr_err("Invalid device tree blob header\n");
+ return;
+ }
+
/* First pass, scan for size */
start = ((unsigned long)initial_boot_params) +
be32_to_cpu(initial_boot_params->off_dt_struct);