According to certain embodiments, a system includes one or more processors and one or more computer-readable non-transitory storage media comprising instructions that, when executed by the one or more processors, cause one or more components to perform operations including executing a software process of a secondary instance, the secondary instance running in parallel with a primary instance and associated with a plurality of cores including a bootstrap core, registering a non-maskable interrupt for the bootstrap core in the secondary instance, determining whether the secondary instance is in a fault state, wherein, if the secondary instance is in the fault state, halting the plurality of cores associated with the secondary instance, without impact to the primary instance, and recovering the bootstrap core by switching a context of the bootstrap core from the secondary instance to the primary instance via the non-maskable interrupt.

Processors employing memory bypassing in memory data dependent instructions as a store data forwarding mechanism, and related methods. To reduce stalls of memory data dependent, load-based instructions, a memory data dependency detection circuit is configured to detect a memory hazard between a store-based instruction and a load-based instruction based on their opcodes and designation/source operands. Some store-based and load-based instructions have opcodes identifying these instructions as having respective store and load address operand types that can be compared without resolution of their respective store and load addresses. For these detected types of instructions, the memory data dependency detection circuit is configured to determine if a source operand of a load-based instruction matches a target operand of a store-based instruction to detect a memory hazard earlier in the instruction pipeline. Identifying memory hazards earlier in an instruction pipeline can allow memory dependent instructions to be processed with avoided or reduced stalls.

Techniques of adapting an interrupt escalation path are implemented in hardware. An interrupt controller receives, from a physical thread of the processor core, a request to adapt, in an event assignment data structure, an escalation path for a specified event source, where the escalation path includes a pointer to a first event notification descriptor. The interrupt controller reads an entry for the physical thread in an interrupt context data structure to determine a virtual processor thread running on the physical thread. Based on the virtual processor thread determined from the interrupt context data structure, the interrupt controller accesses an entry in a virtual processor data structure to determine a different second event notification descriptor to which escalations are to be routed. The interrupt controller updates the pointer in the event assignment data structure to identify the second event notification descriptor, such that the interrupt escalation path is adapted.

An apparatus comprises processing circuitry 14 to perform data processing in response to instructions, the processing circuitry supporting speculative processing of read operations for reading data from a memory system 20, 22; and control circuitry 12, 14, 20 to identify whether a sequence of instructions to be processed by the processing circuitry includes a speculative side-channel hint instruction indicative of whether there is a risk of information leakage if at least one subsequent read operation is processed speculatively, and to determine whether to trigger a speculative side-channel mitigation measure depending on whether the instructions include the speculative side-channel hint instruction. This can help to reduce the performance impact of measures taken to protect against speculative side-channel attacks.

A data processing apparatus is provided that includes global-history prediction circuitry that provides a prediction of an outcome of a given control flow instruction based on a result of execution of one or more previous control flow instructions. Correction circuitry provides a corrected prediction of the global-history prediction circuitry in respect of the given control flow instruction and cache circuitry, separate from the correction circuitry, stores the corrected prediction in respect of the given control flow instruction.

A processor comprising a processor pipeline comprising one or more execution units configured to execute branch instructions, a branch predictor associated with the processor pipeline and configured to predict a branch instruction prediction outcome, and the branch prediction unit. The branch predictor is turned off to save power and avoid miss-predictions when the branch predictor and/or branch prediction unit accuracy is lower than expected.

An apparatus and method is provided, the apparatus comprising a processor pipeline to execute instructions, a cache structure to store information for reference by the processor pipeline when executing said instructions; and prefetch circuitry to issue prefetch requests to the cache structure to cause the cache structure to prefetch information into the cache structure in anticipation of a demand request for that information being issued to the cache structure by the processor pipeline. The processor pipeline is arranged to issue a trigger to the prefetch circuitry on detection of a given event that will result in a reduced level of demand requests being issued by the processor pipeline, and the prefetch circuitry is configured to control issuing of prefetch requests in dependence on reception of the trigger.

Operating system deactivation of write protection for a storage block is provided absent quiescing of processors in a multi-processor computing environment. The process includes receiving an address translation protection exception interrupt resulting from an attempted write access by a processor to a storage block, and determining by the operating system whether write protection for the storage block is active. Based on write protection for the storage block not being active, the operating system issues an instruction to clear or modify translation lookaside buffer entries of the processor associated with the storage block, absent waiting for an action by another processor of multiple processors of the computing environment, to facilitate write access to the storage block proceeding at the processor.

A computer system, processor, programming instructions and/or method of processing data that includes a main register file having a plurality of entries for storing data; an accumulator register file having a plurality of entries for storing data wherein multiple main register file entries are mapped to one accumulator register file entry in the at least one accumulator register file; a logical register mapper to track and map logical registers to main register file entries, and a history buffer. Processing wide data width instructions includes evicting and restoring information from a single primary entry in the logical register mapper through a single read or write port in the logical register mapper without evicting or restoring the remaining other multiple main register file entries mapped in the accumulator register.

Data processing circuitry comprises out-of-order instruction execution circuitry; register mapping circuitry to map zero or more architectural processor registers relating to execution of that program instruction to respective ones of a set of physical processor registers; commit circuitry to commit, in a program code order, the results of executed program instructions, the commit circuitry being configured to access a data store which stores register tag data to indicate which physical registers mapped by the register mapping circuitry relate to a given program instruction; fault detection circuitry to detect a memory access fault in respect of a vector memory access operation and to generate fault indication data indicative of an element earliest in the element order for which a memory access fault was detected; a fault indication register to store the fault indication data, in which the register mapping circuitry is configured to generate a register mapping for a program instruction for any architectural processor registers relating to execution of that program instruction other than the fault indication register; and control circuitry to encode the fault indication data, applicable to a program instruction not yet committed by the commit circuitry, to register tag data associated with that program instruction.