Apparatus and Method to Inject Non-Canonical Addresses into Faulting Instruction Outputs to Mitigate Transient Execution Vulnerabilities

A method, comprising:

• decoding a sequence of instructions by a decoder of a processor, the sequence of instructions including a conditional instruction;
• executing the conditional instruction, wherein executing includes:
• outputting a valid address value indicated by the conditional instruction to a destination when a condition associated with the conditional instruction is determined to be true;
• and
• setting an output fault value associated with the conditional instruction to a non-canonical address value or a truncated portion of the non-canonical address value when the condition associated with the conditional instruction is determined to be false, and outputting the non-canonical address value or truncated portion of the non-canonical address value to the destination.

A machine-readable medium having program code stored thereon which, when executed by a machine, causes the machine to perform additional operations, comprising:

• decoding a sequence of instructions by a decoder of a processor, the sequence of instructions including a conditional instruction;
• executing the conditional instruction, wherein executing includes:
• outputting a valid address value indicated by the conditional instruction to a destination when a condition associated with the conditional instruction is determined to be true;
• and
• setting an output fault value associated with the conditional instruction to a non-canonical address value or a truncated portion of the non-canonical address value when the condition associated with the conditional instruction is determined to be false, and outputting the non-canonical address value or truncated portion of the non-canonical address value to the destination.