Abstract: There is provided a data processing apparatus comprising a plurality of registers, each of the registers having data bits to store data and metadata bits to store metadata. Each of the registers is adapted to operate in a metadata mode in which the metadata bits and the data bits are valid, and a data mode in which the data bits are valid and the metadata bits are invalid. Mode bit storage circuitry indicates whether each of the registers is in the data mode or the metadata mode. Execution circuitry is responsive to a memory operation that is a store operation on one or more given registers.

Abstract: An apparatus and method for constraining access to memory using capabilities. Processing circuitry performs operations during which access requests to memory are generated, with memory addresses for the access requests being generated using capabilities that identify constraining information. Capability checking circuitry performs a capability check operation to determine whether a given access request whose memory address is generated using a given capability is permitted based on the constraining information. Memory access checking circuitry then further constrains access to the memory by the given access request in dependence on a level of trust. The given capability has a capability level of trust associated therewith, and the level of trust associated with the given access request is dependent on both the current mode level of trust associated with the current mode of operation of the processing circuitry, and the capability level of trust of the given capability.

Abstract: Data processing apparatuses, methods and computer programs are disclosed. A range definition register is arranged to store a range specifier and filtering operations are performed with respect to a specified transaction by reference to the range definition register. The range definition register stores the range specifier in a format comprising a significand and an exponent, wherein a range of data identifiers is at least partially defined by the range specifier. When the specified transaction is with respect to a data identifier within the range of data identifiers, the filtering operations performed are dependent on attribute data associated with the range of data identifiers.

Abstract: A data processing system includes processing circuitry for executing context-data-dependent program instructions which are decoded by decoder circuitry. Such context-data-dependent program instructions perform processing which is dependent upon currently existing context data. As an example, the context-data-dependent program instructions may be floating point instructions and the context data may be rounding mode information. The decoder circuitry supports a context save instruction which saves context data when it is marked as having been used and saves default context data when the current context data is marked as not having been used. The decoder circuitry further supports a context restore instruction which restores context data when the current context data is marked as having been used and permits the current context data to continue for future use when it is marked as currently unused.

Abstract: Apparatus comprises a processor to execute program instructions stored at respective memory addresses, processing of the program instructions being constrained by a prevailing capability defining at least access permissions to a set of one or more memory addresses; the processor comprising: control flow change handling circuitry to perform a control flow change operation, the control flow change operation defining a control flow change target address indicating the address of a program instruction for execution after the control flow change operation; and capability generating circuitry to determine, in dependence on the control flow change target address, an address at which capability access permissions data is stored; the capability generating circuitry being configured to retrieve the capability access permissions data and to generate a capability for use as a next prevailing capability in dependence upon at least the capability access permissions data.

Abstract: There is provided a data processing apparatus comprising a plurality of registers, each of the registers having data bits to store data and metadata bits to store metadata. Each of the registers is adapted to operate in a metadata mode in which the metadata bits and the data bits are valid, and a data mode in which the data bits are valid and the metadata bits are invalid. Mode bit storage circuitry indicates whether each of the registers is in the data mode or the metadata mode. Execution circuitry is responsive to a memory operation that is a store operation on one or more given registers.

Abstract: Data processing apparatuses, methods and computer programs are disclosed. A range definition register is arranged to store a range specifier and filtering operations are performed with respect to a specified transaction by reference to the range definition register. The range definition register stores the range specifier in a format comprising a significand and an exponent, wherein a range of data identifiers is at least partially defined by the range specifier. When the specified transaction is with respect to a data identifier within the range of data identifiers, the filtering operations performed are dependent on attribute data associated with the range of data identifiers.

Abstract: A data processing system provides a branch forward instruction (BF) which has programmable parameters specifying a branch target address to be branched to and a branch point identifying a program instruction following the branch forward instruction which, when reached, is followed by a branch to the branch target address.

Abstract: A data processing system includes processing circuitry for executing context-data-dependent-program instructions which are decoded by decoder circuitry. Such context-data-dependent program instructions perform processing which are dependent upon currently existing context data. As an example, the context-data-dependent program instructions may be floating point instructions and the context data may be rounding mode information. The decoder circuitry supports a context save instruction which saves context data when it is marked as having been used and saves default context data when the current context data is marked as not having been used. The decoder circuitry further supports a context restore instruction which restores context data when the current context data is marked as having been used and permits the current context data to continue for future use when it is marked as currently unused.

Abstract: A data processing system provides a branch forward instruction (BF) which has programmable parameters specifying a branch target address to be branched to and a branch point identifying a program instruction following the branch forward instruction which, when reached, is followed by a branch to the branch target address.