ARM64: fix framepointer check in unwind_frame

We need at least 24 bytes above frame pointer.
Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/stacktrace.c

@@ -43,7 +43,7 @@ int unwind_frame(struct stackframe *frame)
 	low  = frame->sp;
 	high = ALIGN(low, THREAD_SIZE);
 
-	if (fp < low || fp > high || fp & 0xf)
+	if (fp < low || fp > high - 0x18 || fp & 0xf)
 		return -EINVAL;
 
 	frame->sp = fp + 0x10;