Arm Limited

Jacob Paul Bramley

Georgia Kouveli

Ruben Borisovich Ayrapetyan

Martyn Maurice Capewell

Kevin Brodsky

Pierre Denis Michel Langlois

Key capability storage circuitryis provided to store a key capability specifying key bounds indicating information indicative of permissible bounds for information specified by any one or more of: a non-capability operand, a capability, or the key capability itself. For a given software compartment executed by the processing circuitry, which lacks a key capability operating privilege associated with at least a portion of the key capability storage circuitry, the processing circuitry is configured to prohibit certain manipulations of the key capability, including a transfer between key capability storage and a memory location selected by the given software compartment. This can help to support temporal safety.

Key capability storage

An apparatus has tag checking circuitry responsive to a target address to: identify a guard tag stored in a memory system in association with a block of one or more memory locations, the block containing a target memory location identified by the target address, perform a tag check based on the guard tag and an address tag associated with the target address, and in response to detecting a mismatch in the tag check, perform an error response action. The apparatus also has tag mapping storage circuitry to store mapping information indicative of a mapping between guard tag values and corresponding address tag values. The tag checking circuitry remaps at least one of the guard tag and the address tag based on the mapping information stored by the tag mapping storage circuitry to generate a remapped tag for use in the tag check.

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Cambridge, United Kingdom

Jacob Paul Bramley