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-rw-r--r--arch/microblaze/kernel/head.S17
1 files changed, 13 insertions, 4 deletions
diff --git a/arch/microblaze/kernel/head.S b/arch/microblaze/kernel/head.S
index e568d6ec621..e41c6ce2a7b 100644
--- a/arch/microblaze/kernel/head.S
+++ b/arch/microblaze/kernel/head.S
@@ -31,6 +31,7 @@
#include <linux/linkage.h>
#include <asm/thread_info.h>
#include <asm/page.h>
+#include <asm/prom.h> /* for OF_DT_HEADER */
#ifdef CONFIG_MMU
#include <asm/setup.h> /* COMMAND_LINE_SIZE */
@@ -54,11 +55,19 @@ ENTRY(_start)
andi r1, r1, ~2
mts rmsr, r1
-/* save fdt to kernel location */
-/* r7 stores pointer to fdt blob */
- beqi r7, no_fdt_arg
+/* r7 may point to an FDT, or there may be one linked in.
+ if it's in r7, we've got to save it away ASAP.
+ We ensure r7 points to a valid FDT, just in case the bootloader
+ is broken or non-existent */
+ beqi r7, no_fdt_arg /* NULL pointer? don't copy */
+ lw r11, r0, r7 /* Does r7 point to a */
+ rsubi r11, r11, OF_DT_HEADER /* valid FDT? */
+ beqi r11, _prepare_copy_fdt
+ or r7, r0, r0 /* clear R7 when not valid DTB */
+ bnei r11, no_fdt_arg /* No - get out of here */
+_prepare_copy_fdt:
or r11, r0, r0 /* incremment */
- ori r4, r0, TOPHYS(_fdt_start) /* save bram context */
+ ori r4, r0, TOPHYS(_fdt_start)
ori r3, r0, (0x4000 - 4)
_copy_fdt:
lw r12, r7, r11 /* r12 = r7 + r11 */