powerpc: Check flat device tree version at boot

In commit e6a6928c3ea1 "of/fdt: Convert FDT functions to use libfdt",
the kernel stopped supporting old flat device tree formats. The minimum
supported version is now 0x10.

There was a checking function added, early_init_dt_verify(), but it's
not called on powerpc.

The result is, if you boot with an old flat device tree, the kernel will
fail to parse it correctly, think you have no memory etc. and hilarity
ensues.

We can't really fix it, but we can at least catch the fact that the
device tree is in an unsupported format and panic(). We can't call
BUG(), it's too early.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index cb35c5b3efca9094739c6ed3e468e40e0a81b3f6..59576255d22b24feb5830a259f5721ed6e51b81e 100644 (file)
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -642,6 +642,10 @@ void __init early_init_devtree(void *params)
 
        DBG(" -> early_init_devtree(%p)\n", params);
 
+       /* Too early to BUG_ON(), do it by hand */
+       if (!early_init_dt_verify(params))
+               panic("BUG: Failed verifying flat device tree, bad version?");
+
        /* Setup flat device-tree pointer */
        initial_boot_params = params;