Abstract: A data processing system 2 is provided which is responsive to program instructions that operate in a variable timing mode to require a variable number of processing cycles to complete. The system is also operable in a fixed timing mode, which may be programmable using a bit (or several bits) within a configuration controlling register, to operate in a fixed timing mode in which such instructions are forced to operate using a fixed number of processing cycles. Thus, suppression of instructions which fail their condition codes may be suppressed and early termination of program instructions similarly suppressed in a manner which helps resist an attack upon the security of the system by observing the number of processing cycles required to process certain data.

Abstract: An apparatus for processing data, the apparatus comprising: a processor operable in a plurality of modes and either a secure domain or a non-secure domain including at least one secure mode being a mode in the secure domain; and at least one non-secure mode being a mode in the non-secure domain. When the processor is executing a program in a secure mode, the program has access to secure data which is not accessible when the processor is operating in a non-secure mode. The processor further includes a non-secure translation table base address register and a secure translation table base address register operable in the non-secure and secure domain, respectively, to indicate a region of memory storing either non-secure or secure domain memory mapping data defining how virtual addresses are translated to physical addresses within either the non-secure or secure domain.

Abstract: A data processing apparatus is operable in a plurality of modes and in either a secure domain or a non-secure domain. When operating in a secure mode within the secure domain a program has access to secure data which is not accessible when the processor is operating in a non-secure mode. A vectored interrupt controller is provided to generate an exception handler address in response to an occurrence of an except condition. The vectored interrupt controller is programmable with parameters specifying for each exception condition whether an exception handler in the secure or the non-secure domain should be triggered and an exception handler address for use if the exception occurs when in the appropriate domain. The vectored interrupt controller also includes a parameter specifying a domain switching exception handler address for use if the exception condition occurs when the processor is not in the appropriate domain.

Abstract: There is provided a method of controlling a monitoring function of a processor, the processor being operable in at least two domains, comprising a first domain and a second domain, the first and second domains each comprising at least one mode, the method comprising the steps of: setting at least one control value, the at least one control value relating to a condition and being indicative of whether the monitoring function is allowable in the first domain; and only allowing initiation of the monitoring function in the first domain when the condition is present if its related control value indicates that the monitoring function is allowable. In some embodiments the first domain is a secure domain and the monitoring function is a debug or trace function.

Abstract: The present invention provides a data processing apparatus and method for managing access to a memory within the data processing apparatus. The data processing apparatus comprises a processor operable in a plurality of modes and a plurality of domains, said plurality of domains comprising a secure domain and a non-secure domain, said plurality of modes including at least one non-secure mode being a mode in the non-secure domain and at least one secure mode being a mode in the secure domain, said processor being operable such that when executing a program in a secure mode said program has access to secure data which is not accessible when said processor is operating in a non-secure mode. Further, a memory is provided for storing data required by the processor, and consists of secure memory for storing secure data and non-secure memory for storing non-secure data.

Abstract: The present invention provides a data processing apparatus and method for controlling access to a memory. The data processing apparatus has a secure domain and a non-secure domain, in the secure domain the data processing apparatus having access to secure data which is not accessible in the non-secure domain. The data processing apparatus comprises a device coupled to a memory via a device bus, and operable, when an item of data in the memory is required by the device, to issue onto the device bus a memory access request pertaining to either the secure domain or the non-secure domain. The memory is operable to store data required by the device, and contains secure memory for storing secure data and non-secure memory for storing non-secure data.

Abstract: The present invention provides a data processing apparatus and method for accessing memory. The data processing apparatus has a secure domain and a non-secure domain, in the secure domain the data processing apparatus having access to secure data which is not accessible in the non-secure domain. The data processing apparatus comprises a device coupled via a device bus with the memory, the device being operable, when an item of data in the memory is required by the device, to issue onto the device bus a memory access request pertaining to either the secure domain or the non-secure domain. The memory is operable to store data required by the device, and contains secure memory for storing secure data and non-secure memory for storing non-secure data. In accordance with the invention, the memory access request as issued by the device includes a domain signal identifying whether the memory access request pertains to either the secure domain or the non-secure domain.

Abstract: A processor operable to perform a plurality of functions, the processor comprising: an input port; a storage element operable to receive and to store an input signal input via the input port, the input signal comprising at least one control value; control logic operable to control at least one of the functions of the processor in dependence on the at least one control value; and access logic operable to receive an access control signal and to disable access via the input port to the at least one control value stored in the storage element in dependence upon the access control signal.

Abstract: There is a provided apparatus for processing data, said apparatus comprising:

Abstract: There is a provided a data processing system comprising:

Abstract: There is a provided a data processing system comprising:

Abstract: In a data processing system using multiple operating systems, an interrupt which itself may be interrupted by a subsequent interrupt which will be serviced in a different operating system, guards itself against being overlooked when that subsequent interrupt has been handled by starting a stub interrupt handling routine in that other operating system before executing the main handling routine in the originating operating system. Thus, the stub interrupt handling routine will be recognised in the other operating system irrespective of other interrupt events which may occur and accordingly the interrupted interrupt handling may be restarted.

Abstract: In a system supporting more than one operating system, a data processing thread executing on a first operating system may be subject to an interrupt which triggers interrupt handling on a second operating system. When that interrupt handling is completed on the second operating system, the first operating system is resumed using a return interrupt. The return interrupt specifies the data processing thread which is active on the second operating system such that an appropriate task switch or resumption may be made on the first operating system. The technique is particularly well suited to systems utilising a secure operating system and a non-secure operating system executing on the same hardware.

Abstract: There is provided apparatus for processing data, said apparatus comprising:

Abstract: The present invention provides a data processing apparatus and method for controlling access to a memory unit. The data processing apparatus comprises a processor operable in a plurality of modes and a plurality of domains, said plurality of domains comprising a secure domain and a non-secure domain, said plurality of modes including at least one non-secure mode being a mode in the non-secure domain and at least one secure mode being a mode in the secure domain. The processor is operable such that when executing a program in a secure mode the program has access to secure data which is not accessible when the processor is operating in a non-secure mode. A memory unit is also provided that comprises a plurality of entries and is operable to store data required by the processor.

Abstract: There is a provided a data processing system comprising:

Abstract: Data values being stored and transferred within a data processing system 8 have a selectable representation, such as true and complement, as indicated by an accompanying representation specifying bit. This assists in obscuring the operation and the power signature of the device in a manner that improves security.

Abstract: Data processing apparatuses provided comprising a memory operable to store a plurality of data words, each data word being associated with at least one status bit giving information regarding a status of said data word; a status bit store operable to store said status bits within a hierarchical relationship such that a combined status relating to a plurality of first level status bits at a first level within said hierarchical relationship is indicated by a second level status bit at a second level within said hierarchical relationship, said second level being higher in said hierarchical relationship than said first level; and status querying logic operative to determine a status of a data word within said memory by examining status bits within said status bit store starting at a top level within said hierarchical relationship and working down through said hierarchical relationship until a status bit is reached that indicates said status of said data word independently of any status bits lower in said hierarch

Abstract: A data processing system incorporating a cache memory 2 and a central processing unit. A storage control circuit 10 is responsive to a programmable partition setting PartVal to partition the cache memory between instruction words and data words in dependence upon whether the central processing unit 4 indicates with signal I/D whether the word to be stored within the cache memory 2 resulted from an instruction word cache miss or data word cache miss. The cache memory array 2 may have a programmably sized portion locked down so that it is not replaced. The selection within the complementary programmable range where overwriting takes place uses a pseudo random selection technique using pseudo random number generator in the form of a linear feedback shift register triggering incrementing of a counter.

Abstract: A data processing system and method include an address space which is controlled by a memory management unit and which is treated as being divided into main-sections (chunks) and sub-sections (grains). The grains may be configured to be of one of a selected number of sizes. Irrespective of the grain size, there is a fixed number of grains within each chunk. A bank of grain registers 20 stores access control parameters for each grain. In operation, a memory address (va?31:0!) is decoded to determine which chunk it relates to so that the grain size for that chunk may be determined. Having determined the grain size, the rest of the address may be decoded to pick out the grain in which the address is located, and then the access control parameters for that grain are recovered.