Arm Limited

Matthew James Horsnell

Stephan Diestelhorst

Richard Roy Grisenthwaite

Grigorios Magklis

Stuart David Biles

Mbou Eyole

Daniel Kershaw

Giacomo Gabrielli

Andreas Lars Sandberg

Guy Larri

Daren Croxford

Michael John Williams

Thomas Philip Speier

Wei Wang

Roberto Lopez Mendez

Balaji Venu

Xabier Iturbe

Eric Ola Harald Liljedahl

David Michael Gilday

Reiley Jeyapaul

Christopher Daniel Emmons

Roko Grubisic

Timothy Hayes

Ilias Vougioukas

Syed Ali Mustafa Zaidi

Nathan Yong Seng Chong

Robin Alexander Emery

In response to instruction decoding circuitry decoding a conditional write instruction, processing circuitry determines whether a predetermined condition is satisfied for a target cache line corresponding to a target address specified by the conditional write instruction. If the predetermined condition is satisfied for the target cache line, a write request is issued to update the target cache line. If the predetermined condition is not satisfied for the target cache line, a failure indication is returned. The processing circuitry selects, depending on whether the sequence of instructions specifies cache-line-retention hint information applicable to the conditional write instruction, whether to prevent a unique coherency state of the target cache line being relinquished by a local cache associated with the processing circuitry for a retention period following processing of the conditional write instruction. The unique coherency state comprises a coherency state in which the processing circuitry has exclusive right to update the target cache line.

Cache-line retention hint information for conditional write instruction

An apparatus comprises an instruction decoderand processing circuitry. Monitoring circuitrymonitors one or more events indicative of a potential update to data associated with any of a monitored set of addresses, and makes accessible to software executing on the processing circuitrya monitoring reporting indication indicative of whether any events has occurred for at least one of the monitored set of addresses. In response to decoding of an exclusive status setting instruction specifying a given address, the processing circuitrysets an exclusive status associated with the given address. The exclusive status is cleared in response to detecting an event indicative of a conflicting memory access to the given address. In response to decoding of a monitor exclusive instruction, the processing circuitry: determines whether the exclusive status is associated with a target address, and if so allocates the target address to be one of the monitored set of addresses.

Monitor exclusive instruction

Briefly, example methods, apparatuses, and/or articles of manufacture are disclosed that may be implemented, in whole or in part, using one or more processing devices to facilitate and/or support one or more operations and/or techniques for authenticating an identity of a subject. In particular, some embodiments are directed to techniques for authentication of an identity of a subject as being an identity of a particular unique individual based, at least in part, on involuntary responses by the subject to sensory stimuli.

Electronic authentication system, device and process

An apparatus comprises address storage circuitry to store indications of a first set of memory locations of a shared memory; a capacity indicator to indicate whether a capacity of the address storage circuitry has been reached, and monitoring circuitry to monitor the first set of memory locations and a second set of memory locations of the shared memory, identified in further storage circuitry to identify whether data stored at either set of memory locations has been modified. The monitoring circuitry is responsive to determining that the data has been modified to generate an indication that the data has been modified, and processing circuitry receives the indication and executes a monitor-address instruction specifying an address of a new memory location in the shared memory to update the address storage circuitry or the further storage circuitry to indicate the new address, depending on the capacity indicator.

Monitoring memory locations to identify whether data stored at the memory locations has been modified

An apparatus has processing circuitry with support for transactional memory, and a cache hierarchy comprising at least two levels of cache. In response to a draining trigger event having potential to cause loss of state stored in at least one further level cache beyond a predetermined level cache in which speculative store data generated by a transaction is marked as speculative until the transaction is committed, draining circuitry performs a draining operation to scan a subset of the cache hierarchy to identify dirty cache lines and write data associated with the dirty cache lines to persistent memory. The subset of the cache hierarchy includes the at least one further level cache. In the draining operation, speculative store data marked as speculative in the predetermined level cache is prevented from being drained to the persistent memory.

Draining operation for draining dirty cache lines to persistent memory

Briefly, example methods, apparatuses, and/or articles of manufacture are disclosed that may be implemented, in whole or in part, using one or more processing devices to facilitate and/or support one or more operations and/or techniques for authenticating an identity of a human subject. In particular, some embodiments are directed to techniques for authentication of an identity of a human subject as being an identity of a particular unique individual based, at least in part, on involuntary responses by the human subject to sensory stimuli.

Authentication system, device and process

An apparatus and method are provided for monitoring events in a data processing system. The apparatus has first event monitoring circuitry for monitoring occurrences of a first event within a data processing system, and for asserting a first signal to indicate every m-th occurrence of the first event, where m is an integer of 1 or more. In addition second event monitoring circuitry is used to monitor occurrences of a second event within the data processing system, and to assert a second signal to indicate every n-th occurrence of the second event, where n is an integer of 1 or more. History maintenance circuitry then maintains event history information which is updated in dependence on the asserted first and second signals. Further, history analysis circuitry is responsive to an analysis trigger to analyse the event history information in order to detect a reporting condition when the event history information indicates that a ratio between occurrences of the first event and the occurrences of the second event is outside an acceptable range. The history analysis circuitry is then responsive to detection of the reporting condition to assert a report signal. This provides a particularly efficient and effective mechanism for monitoring ratios of events within a data processing system.

Apparatus and method for monitoring events in a data processing system

In a system providing transactional memory support, a transaction nesting depth testing instruction is provided for triggering processing circuitry 4 to set at least one status value to one of a plurality of states depending on a transaction nesting depth indicative of a number of executed transaction start instructions of a given thread for which the corresponding transaction remains unaborted and uncommitted, the plurality of states including a first state selected when the transaction nesting depth is 1 and at least one further state selected when the transaction nesting depth is greater than or less than 1. The supported ISA enables the setting of the at least one status value and a conditional branch conditional on the at least one status value being in the first state to be performed in response to a single transaction nesting depth testing instruction and a single conditional branch instruction.

Transaction nesting depth testing instruction

A data processing apparatus has processing circuitry with transactional memory support circuitry to support execution of a transaction using transactional memory. In response to an exception mask updating instruction which updates exception mask information to enable at least one subset of exceptions which was disabled at the start of processing of a transaction, the processing circuitry permits un-aborted processing of one or more subsequent instruction of the transaction that follow the exception mask update instruction.

Permitting unaborted processing of transaction after exception mask update instruction

A data processing system () including one or more transaction buffers () storing address translation data executes translation buffer invalidation instructions TLBI within respective address translation contexts VMID, ASID, X. Translation buffer invalidation signals generated as a consequence of execution of the translation buffer invalidation instructions are broadcast to respective translation buffers and include signals which specify the address translation context of the translation buffer invalidation instruction that was executed. This address translation context specified within the translation buffer invalidation signals is used to gate whether or not those translation buffer invalidation signals when received by translation buffers which are potential targets for the invalidation are or are not flushed. The address translation context data provided within the translation buffer invalidation signals may also be used to control whether or not local memory transactions for a local transactional memory access are or are not aborted upon receipt of the translation buffer invalidation signals.

Address translation data invalidation

An apparatus is described with support for transactional memory and load/store-exclusive instructions using an exclusive monitor indication to track exclusive access to a given address. In response to a predetermined type of load instruction specifying a load target address, which is executed within a given transaction, any exclusive monitor indication previously set for the load target address is cleared. In response to a load-exclusive instruction, an abort is triggered for a transaction for which the given address is specified as one of its working set of addresses. This helps to maintain mutual exclusion between transactional and non-transactional threads even if there is load speculation in the non-transactional thread.

Handling load-exclusive instructions in apparatus having support for transactional memory

An apparatus and a method of operating a data processing apparatus, and simulators thereof, are disclosed. Data processing circuitry performs data processing operations in response to instructions, where some sets of instructions may be defined as a transaction which are to be performed atomically with respect to other operations performed by the data processing circuitry. When a synchronous exception occurs during a transaction the transaction is aborted and an exception counter is incremented. When the counter reaches a threshold value a transaction failure signal is generated, allowing, if appropriate a response to this number of exceptions causing transaction aborts to be carried out.

Exception handling in transactions

An apparatus comprising: processing circuitry to process threads of data processing; and transactional memory support circuitry to support execution of a transaction within a thread processed by the processing circuitry. In response to a transactional compare-and-discard instruction executed within a given transaction, specifying a target address and a compare value, the processing circuitry loads a target data value from a memory location corresponding to the target address; sets at least one condition status indication depending on a result of comparing the target data value and the compare value; and discards the target data value without adding the target address to a working set of addresses tracked for the given transaction. This is useful for enabling thread level speculation to be implemented on a transactional memory architecture.

Transactional compare-and-discard instruction

In an apparatus with transactional memory support circuitry, for a first type of transaction started using a first type of transaction start instruction, commitment of results of instructions executed speculatively following the first type of transaction start instruction are prevented until a transaction end instruction is reached. An abort is triggered when a conflict is detected between an address of a memory access from another thread and the addresses tracked for the transaction. For a second type of transaction started using a second type of transaction start instruction, an address of the read operation is marked as trackable whilst an address of a write operation is omitted from being marked as trackable. This allows an apparatus that supports transactional memory to also be used for multi-word address watching.

Apparatus and data processing method for transactional memory

In an apparatus () with transactional memory support, a predetermined type of transaction start instruction or a subsequent instruction following the predetermined type of transaction start instruction triggers capture of a lock identifier which identifies a lock variable for controlling exclusive access to at least one resource. In response to a predetermined type of transaction end instruction which follows the predetermined type of transaction start instruction, the lock variable is checked and commitment of results of speculatively executed instructions of the transaction is prevented or deferred when the lock variable indicates that another thread holds the exclusive access to the target resource. This approach can improve performance when executing transactions in a transactional memory based system.

Growing community of inventors

Cambridge, United Kingdom

Matthew James Horsnell