ARM: kexec: remove 512MB restriction on kexec crashdump

The real limit is the top of the visible physical address space with
the MMU turned off.  Hence, we need to limit the crash kernel allocation
running-view physical address of the top of the boot-view physical
address space.
Reviewed-by: NPratyush Anand <panand@redhat.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/setup.c

@@ -943,7 +943,6 @@ late_initcall(init_machine_late);
  * zImage relocating below the reserved region.
  */
 #define CRASH_ALIGN	(128 << 20)
-#define CRASH_ADDR_MAX	(PHYS_OFFSET + (512 << 20))
 
 static inline unsigned long long get_total_mem(void)
 {
@@ -973,9 +972,7 @@ static void __init reserve_crashkernel(void)
 		return;
 
 	if (crash_base <= 0) {
-		unsigned long long crash_max = CRASH_ADDR_MAX;
-		if (crash_max > (u32)~0)
-			crash_max = (u32)~0;
+		unsigned long long crash_max = idmap_to_phys((u32)~0);
 		crash_base = memblock_find_in_range(CRASH_ALIGN, crash_max,
 						    crash_size, CRASH_ALIGN);
 		if (!crash_base) {