Recording set indicator
AssigneeArm Limited
InventorAlasdair Grant
Life of this patent
Estimating the term…
Abstract
An apparatus comprises processing circuitry for accessing data in a physically-indexed cache. Set indicator recording circuitry is provided to record a set indicator corresponding to a target physical address, where the set indicator depends on which set of one or more storage locations of the cache corresponds to the target physical address. The set indicator is insufficient to identify the target physical address itself. This enables performance issues caused by contention of data items for individual sets in a physically-indexed set-associative or direct-mapped cache to be identified without needing to expose the physical address itself to potentially insecure processes or devices.
Claims22
An apparatus comprising:
- processing circuitry configured to access data in a cache indexed by a physical address translated from a virtual address;
- and
- set indicator recording circuitry configured to record a set indicator corresponding to a target physical address, wherein the set indicator is dependent on which of a plurality of sets of one or more storage locations of the cache corresponds to the target physical address, and the set indicator is insufficient to identify the target physical address;
- wherein the set indicator recording circuitry is configured to make the set indicator accessible to an external device to which the target physical address is inaccessible or software process to which the target physical address is inaccessible.
A data processing method comprising:
- translating virtual addresses identified by processed instructions to physical addresses for accessing data in a physically-indexed cache;
- recording a set indicator corresponding to a target physical address, wherein the set indicator is dependent on which of a plurality of sets of one or more storage locations of the cache corresponds to the target physical address, and the set indicator is insufficient to identify the target physical address;
- and
- making the set indicator accessible to an external device to which the target physical address is inaccessible or software process to which the target physical address is inaccessible.
A method comprising:
- reading monitoring data captured during processing performed by processing circuitry configured to access data in a cache indexed by a physical address translated from a virtual address, the monitoring data comprising a plurality of set indicators corresponding to respective physical addresses, wherein each set indicator is dependent on which of a plurality of sets of one or more storage locations of the cache corresponds to the corresponding physical address, and is insufficient to identify the corresponding physical address, wherein the reading is performed by an external device to which the target physical address is inaccessible or software process to which the target physical address is inaccessible;
- and
- comparing respective set indicators to identify whether the corresponding physical addresses map to the same set of the cache.
Dependencies are inferred from the claim text.