Secure Monitor Call causes an exception to EL3.
SMC is available only for software executing at EL1 or higher. It is undefined in EL0.
If the values of HCR_EL2.TSC and SCR_EL3.SMD are both 0, execution of an SMC instruction at EL1 or higher generates a Secure Monitor Call exception, recording it in ESR_ELx, using the EC value 0x17, that is taken to EL3.
If the value of HCR_EL2.TSC is 1 and EL2 is enabled in the current Security state, execution of an SMC instruction at EL1 generates an exception that is taken to EL2, regardless of the value of SCR_EL3.SMD. For more information, see Traps to EL2 of Non-secure EL1 execution of SMC instructions.
bits(16) imm = imm16;