Arm Limited

Alexander Donald Charles Chadwick

Andrew Brookfield Swaine

Jason Parker

Yuval Elad

Richard Roy Grisenthwaite

Simon John Craske

Thomas Christopher Grocutt

Abhishek Raja

Jonathan Curtis Beard

Timothy Hayes

Carlos Garcia-Tobin

Gareth James Evans

Charles Andrew Giefer

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

Apparatuses, methods and techniques for controlling memory access in a data processing system are disclosed. The operating data processing system comprises multiple subsystems, each comprising at least one processing element and at least one peripheral device. Memory transaction control circuitry receives memory transaction information of a memory transaction comprising a stream identifier indicative of the issuing peripheral device. A main control register indicates an address of a stream table having multiple entries each comprising an owning subsystem identifier. At least one subsystem control register corresponding to each subsystem of the multiple subsystems stores memory access checking configuration information. On receipt of the memory transaction information an entry of the stream table is selected in dependence on the stream identifier. At least one subsystem control register. corresponding to the subsystem identified by the owning subsystem identifier of the entry is selected.

Controlling memory access in a data processing systems with multiple subsystems

An apparatus comprising translation circuitry to perform a translation operation to generate a translated second memory address within a second memory address space as a translation of a first memory address within a first memory address space, in which the translation circuitry is configured to generate the translated second memory address in dependence upon translation information stored at one or more translation information addresses; permission circuitry to perform an operation to detect permission information to indicate, for a given second memory address, whether memory access is permitted to the given second memory address; and access circuitry to allow access to data stored at the given second memory address when the permission information indicates that memory access is permitted to the given second memory address.

Apparatus and method

An apparatus has memory management circuitry to control access to a memory system based on access control information defined in table entries of a table structure comprising at least two levels of access control table. Table accessing circuitry accesses the table structure to obtain the access control information corresponding to a target address. For a given access control table at a given level of the table structure other than a starting level, the table accessing circuitry selects a selected table entry of the given access control table corresponding to the target address, based on an offset portion of the target address. A size of the offset portion is selected based on a variable nesting control parameter specified in a table entry of a higher-level access control table at a higher level of the table structure than the given access control table.

Variable nesting control parameter for table structure providing access control information for controlling access to a memory system

There is provided a data processing apparatus and method of data processing. The data processing apparatus comprises storage circuitry to store a hierarchy of page tables comprising an intermediate level page table. Each entry of the intermediate level page table comprises base address information of a next level page table and control information indicating whether an addressing function has been applied to reorder physical storage locations of entries of the next level page table. Address translation circuitry is provided to perform address translations in response to receipt of a virtual address by performing a lookup in a next level page table dependent on the base address information and a page table index from the virtual address. When the control information indicates that the addressing function has been applied, the lookup is performed at a modified storage location generated by applying the addressing function to the page table index.

Data processing apparatus and method for performing address translation

An apparatus comprises memory access circuitry to access a memory system; a plurality of memory mapped registers, including at least an insert register and a producer pointer register; and control circuitry to perform an insert operation in response to receipt of an insert request from a requester device sharing access to the memory system. The insert request specifies an address mapped to the insert register and an indication of a payload. The insert operation includes controlling the memory access circuitry to write the payload to a location in the memory system selected based on a producer pointer value stored in the producer pointer register, and updating the producer pointer register to increment the producer pointer value.

Growing community of inventors

Cambridge, United Kingdom

Alexander Donald Charles Chadwick