Arm Limited

Timothy Hayes

Mbou Eyole

Giacomo Gabrielli

Jesse Garrett Beu

Alejandro Martinez Vicente

Andrew Brookfield Swaine

Abhishek Raja

Frederic Claude Marie Piry

Peter Richard Greenhalgh

Tushar P Ringe

Ian Michael Caulfield

Matthew James Horsnell

Albin Pierrick Tonnerre

Alastair David Reid

Alejandro Rico Carro

Kishore Kumar Jagadeesha

Alexander Donald Charles Chadwick

There is provided an apparatus, a method, and a computer readable storage medium. The apparatus comprises memory translation circuitry responsive to receipt of a translation request specifying a first address, to perform a page table walk process to identify a corresponding second address. The apparatus is also provided with control circuitry responsive to receipt of a memory synchronisation occurring subsequent to at least one maintenance operation, to implement a delay before performing the memory synchronisation. The delay continues whilst one or more pending memory accesses affected by the maintenance operation are outstanding. The control circuitry is configured to perform a filtering process to identify candidate page table walk processes affected by the maintenance operation and, for each candidate page table walk, to cancel the candidate page table walk process and to issue a replayed translation request to trigger a replay of the candidate page table walk process.

Memory synchronisation subsequent to a page table walk

A data processing apparatus is provided which controls the use of data in respect of a further operation. The data processing apparatus identifies whether data is trusted or untrusted by identifying whether or not the data was determined by a speculatively executed resolve-pending operation. A permission control unit is also provided to control how the data can be used in respect of a further operation according to a security policy while the speculatively executed operation is still resolve-pending.

Controlling use of data determined by a resolve-pending speculative operation

An apparatus comprises an interconnect providing communication paths between agents coupled to the interconnect. A coordination agent is provided which performs an operation requiring sending a request to each of a plurality of target agents, and receiving a response from each of the target agents, the operation being unable to complete until the response has been received from each of the target agents. Storage circuitry is provided which is accessible to the coordination agent and configured to store, for each agent that the coordination agent may communicate with via the interconnect, a latency indication for communication between that agent and the coordination agent. The coordination agent is configured, prior to performing the operation, to determine a sending order in which to send the request to each of the target agents, the sending order being determined in dependence on the latency indication for each of the target agents.

Sending a request to agents coupled to an interconnect

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

An apparatus and method of operating the apparatus are provided for performing a count operation. Instruction decoder circuitry is responsive to a count instruction specifying an input data item to generate control signals to control the data processing circuitry to perform a count operation. The count operation determines a count value indicative of a number of input elements of a subset of elements in the specified input data item which have a value which matches a reference value in a reference element in a reference data item. A plurality of count operations may be performed to determine a count data item corresponding to the input data item. A register scatter storage instruction, a gather index generation instruction, and respective apparatuses responsive to them, as well as simulator implementations, are also provided.

Counting elements in data items in a data processing apparatus

An apparatus and a method of operating the apparatus are provided for performing a comparison operation to match a given sequence of values within an input vector. Instruction decoder circuitry is responsive to a string match instruction specifying a segment of an input vector to generate control signals to control the data processing circuitry to perform a comparison operation. The comparison operation determines a comparison value indicative of whether each input element of a required set of consecutive input elements of the segment has a value which matches a respective value in consecutive reference elements of the reference data item. A plurality of comparison operations may be performed to determine a match vector corresponding to the segment of the input vector to indicate the start position of the substring in the input vector. A string match instruction, as well as simulator virtual machine implementations, are also provided.

Matching consecutive values in a data processing apparatus

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Cambridge, United Kingdom

Timothy Hayes