Speculation with indirect control flow instructions

摘要

Input data 900 is received, e.g. by a compiler, and a sequence of instructions for execution by a processing circuitry is outputted. The sequence comprises an indirect control flow instruction 910 comprising a field indicating where a target of the instruction is stored. The sequence comprises at least one instruction to store a state of control‑flow‑speculation (sstate) after execution of the indirect‑control‑flow‑instruction. This way it can be determined whether the destination of the branch was correct. An instruction in the sequence, e.g. an access instruction, is inhibited from being subject to data value speculation, e.g. via a CSDB barrier. Indirect control flow instruction 910 comprises a multi‑target branch instruction, e.g. switch statement, and a variable i for determining the target. Sstate indicates whether control‑flow‑speculation occurred correctly by determining at each target whether the value of variable i corresponds to the associated target. Secure data leaks by side-channel attacks are addressed.