Techniques For Metadata Processing

A non-transitory computer readable medium comprising code stored thereon that, when executed by a processor, performs a method of processing instructions comprising:

• receiving, for metadata processing, a current instruction with an associated metadata tag, the metadata processing being performed in a metadata processing domain isolated from a code execution domain including the current instruction;
• determining, in the metadata processing domain and in accordance with the metadata tag and the current instruction, whether a rule exists in a rule cache for the current instruction, the rule cache including rules on metadata used by the metadata processing to define allowed operations;
• and
• responsive to determining no rule exists in the rule cache for the current instruction, performing rule cache miss processing in the metadata processing domain including determining whether execution of the current instruction is one of allowed and disallowed;
• responsive to determining the current instruction is allowed to be executed in the code execution domain, generating a new rule for the current instruction;
• and
• responsive to writing to a register in the metadata processing domain, inserting the new rule into the rule cache;
• wherein determining that execution of the current instruction is allowed includes
• determining a privilege level of the current instruction,
• accessing a tag mode register to determine a present security mode of execution of a plurality of security modes of the metadata processing domain, and
• determining that the privilege level of the current instruction is allowed to be executed in the presented determined security mode of execution.

A system comprising:

• a processor;
• and
• a memory comprising code stored thereon that, when executed by the processor, performs a method of processing instructions comprising:
• receiving, for metadata processing, a current instruction with an associated metadata tag, the metadata processing being performed in a metadata processing domain isolated from a code execution domain including the current instruction;
• determining, in the metadata processing domain and in accordance with the metadata tag and the current instruction, whether a rule exists in a rule cache for the current instruction, the rule cache including rules on metadata used by the metadata processing to define allowed operations;
• and
• responsive to determining no rule exists in the rule cache for the current instruction, performing rule cache miss processing in the metadata processing domain including determining whether execution of the current instruction is one of allowed and disallowed;
• responsive to determining the current instruction is allowed to be executed in the code execution domain, generating a new rule for the current instruction;
• and
• responsive to writing to a register in the metadata processing domain, inserting the new rule into the rule cache;
• wherein determining that execution of the current instruction is allowed includes
• determining a privilege level of the current instruction,
• accessing a tag mode register to determine a present security mode of execution of a plurality of security modes of the metadata processing domain, and
• determining that the privilege level of the current instruction is allowed to be executed in the presented determined security mode of execution.