lib: Add misaligned load/store trap handling

We generally don't get misaligned load/store traps from Linux/U-Boot
compiled using GCC 8.2 or higher but this is not true with older
GCC toolchains. To tackle this we add misaligned load/store trap
handling adopted from BBL sources but much more simpler.
(Note: BBL sources can be found at https://github.com/riscv/riscv-pk.git)

Signed-off-by: Anup Patel <anup.patel@wdc.com>

include/sbi/sbi_misaligned_ldst.h

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2018 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#ifndef __SBI_MISALIGNED_LDST_H__
+#define __SBI_MISALIGNED_LDST_H__
+
+#include <sbi/sbi_types.h>
+
+struct sbi_trap_regs;
+struct sbi_scratch;
+
+int sbi_misaligned_load_handler(u32 hartid, ulong mcause,
+				struct sbi_trap_regs *regs,
+				struct sbi_scratch *scratch);
+
+int sbi_misaligned_store_handler(u32 hartid, ulong mcause,
+				 struct sbi_trap_regs *regs,
+				 struct sbi_scratch *scratch);
+
+#endif