[PATCH] powerpc: Auto reserve of device tree blob

A devtree compiler (dtc) generated devtree blob is "relocatable" and so
does not contain a reserved_map entry for the blob itself.  This means
that if passed to Linux, Linux will not get lmb_reserve() the blob and
it could be over.  The following patch will explicitly reserve the
"blob" as it was given to us and stops prom_init.c from creating a
reserved mapping for the blob.

NOTE: that the dtc/kexec should not generate the blob reservation entry.
Although if they do, LMB reserver handles overlaps.
Signed-off-by:   <jimix@watson.ibm.com>
Acked-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/prom.c

@@ -1267,6 +1267,11 @@ static void __init early_reserve_mem(void)
 
 	reserve_map = (u64 *)(((unsigned long)initial_boot_params) +
 					initial_boot_params->off_mem_rsvmap);
+
+	/* before we do anything, lets reserve the dt blob */
+	lmb_reserve(__pa((unsigned long)initial_boot_params),
+		    initial_boot_params->totalsize);
+
 #ifdef CONFIG_PPC32
 	/* 
 	 * Handle the case where we might be booting from an old kexec

arch/powerpc/kernel/prom_init.c

@@ -1950,11 +1950,7 @@ static void __init flatten_device_tree(void)
 	/* Version 16 is not backward compatible */
 	hdr->last_comp_version = 0x10;
 
-	/* Reserve the whole thing and copy the reserve map in, we
-	 * also bump mem_reserve_cnt to cause further reservations to
-	 * fail since it's too late.
-	 */
-	reserve_mem(RELOC(dt_header_start), hdr->totalsize);
+	/* Copy the reserve map in */
 	memcpy(rsvmap, RELOC(mem_reserve_map), sizeof(mem_reserve_map));
 
 #ifdef DEBUG_PROM
@@ -1967,6 +1963,9 @@ static void __init flatten_device_tree(void)
 				    RELOC(mem_reserve_map)[i].size);
 	}
 #endif
+	/* Bump mem_reserve_cnt to cause further reservations to fail
+	 * since it's too late.
+	 */
 	RELOC(mem_reserve_cnt) = MEM_RESERVE_MAP_SIZE;
 
 	prom_printf("Device tree strings 0x%x -> 0x%x\n",