sh: kexec: Add PHYSICAL_START

Add PHYSICAL_START kernel configuration parameter to set the address at
which the kernel should be loaded.

It has been observed on an sh7757lcr that simply modifying MEMORY_START
does not achieve this goal for 32bit sh. This is due to MEMORY_OFFSET in
arch/sh/kernel/vmlinux.lds.S bot being based on MEMORY_START on such
systems.

Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
index 58a93fb3..c9dbace 100644
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -287,6 +287,8 @@
 static void __init early_reserve_mem(void)
 {
 	unsigned long start_pfn;
+	u32 zero_base = (u32)__MEMORY_START + (u32)PHYSICAL_OFFSET;
+	u32 start = zero_base + (u32)CONFIG_ZERO_PAGE_OFFSET;
 
 	/*
 	 * Partially used pages are not usable - thus
@@ -300,15 +302,13 @@
 	 * this catches the (definitely buggy) case of us accidentally
 	 * initializing the bootmem allocator with an invalid RAM area.
 	 */
-	memblock_reserve(__MEMORY_START + CONFIG_ZERO_PAGE_OFFSET,
-		    (PFN_PHYS(start_pfn) + PAGE_SIZE - 1) -
-		    (__MEMORY_START + CONFIG_ZERO_PAGE_OFFSET));
+	memblock_reserve(start, (PFN_PHYS(start_pfn) + PAGE_SIZE - 1) - start);
 
 	/*
 	 * Reserve physical pages below CONFIG_ZERO_PAGE_OFFSET.
 	 */
 	if (CONFIG_ZERO_PAGE_OFFSET != 0)
-		memblock_reserve(__MEMORY_START, CONFIG_ZERO_PAGE_OFFSET);
+		memblock_reserve(zero_base, CONFIG_ZERO_PAGE_OFFSET);
 
 	/*
 	 * Handle additional early reservations