powerpc: Fix device tree claim code

commit 966728dd88b4026ec58fee169ccceaeaf56ef120 upstream.

I have a box that fails in OF during boot with:

DEFAULT CATCH!, exception-handler=fff00400
at   %SRR0: 49424d2c4c6f6768   %SRR1: 800000004000b002

ie "IBM,Logh". OF got corrupted with a device tree string.

Looking at make_room and alloc_up, we claim the first chunk (1 MB)
but we never claim any more. mem_end is always set to alloc_top
which is the top of our available address space, guaranteeing we will
never call alloc_up and claim more memory.

Also alloc_up wasn't setting alloc_bottom to the bottom of the
available address space.

This doesn't help the box to boot, but we at least fail with
an obvious error. We could relocate the device tree in a future
patch.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index bafac2e41ae1..2edcfed63d48 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -890,7 +890,7 @@ static unsigned long __init alloc_up(unsigned long size, unsigned long align)
 	}
 	if (addr == 0)
 		return 0;
-	RELOC(alloc_bottom) = addr;
+	RELOC(alloc_bottom) = addr + size;
 
 	prom_debug(" -> %x\n", addr);
 	prom_debug("  alloc_bottom : %x\n", RELOC(alloc_bottom));
@@ -1704,7 +1704,7 @@ static void __init *make_room(unsigned long *mem_start, unsigned long *mem_end,
 		chunk = alloc_up(room, 0);
 		if (chunk == 0)
 			prom_panic("No memory for flatten_device_tree (claim failed)");
-		*mem_end = RELOC(alloc_top);
+		*mem_end = chunk + room;
 	}
 
 	ret = (void *)*mem_start;
@@ -1923,7 +1923,7 @@ static void __init flatten_device_tree(void)
 	mem_start = (unsigned long)alloc_up(room, PAGE_SIZE);
 	if (mem_start == 0)
 		prom_panic("Can't allocate initial device-tree chunk\n");
-	mem_end = RELOC(alloc_top);
+	mem_end = mem_start + room;
 
 	/* Get root of tree */
 	root = call_prom("peer", 1, 1, (phandle)0);