We should only return valid error codes from SBI ecalls as defined by the RISC-V SBI spec. To achieve this: 1. We use SBI_Exxxx defines for OpenSBI internal errors with error values starting from -1000 2. We use SBI_ERR_xxxx defines for errors defined by SBI spec 3. We map some of the SBI_Exxxx defines to SBI_ERR_xxxx defines which are semantically same 4. We throw a error print and force return error code to SBI_ERR_FAILED in sbi_ecall_handler() if we see an invalid error code being returned to S-mode Signed-off-by: Anup Patel <anup.patel@wdc.com> Reviewed-by: Atish Patra <atish.patra@wdc.com>