Speculation-restricted memory region type

A method for a data processing apparatus comprising processing circuitry capable of speculatively issuing a read request to request that data is read from a target memory region of a memory system;

• the method comprising:
• controlling access to the memory system based on memory attribute data identifying each memory region as one of a plurality of region types;
• and
• in response to a first read request for which the target memory region is indicated as a speculation-restricted region type by the memory attribute data:
• at least when the first read request is non-speculatively issued by the processing circuitry, permitting a subsequent read request to be serviced using data obtained in response to the first read request;
• and
• when the first read request is speculatively issued by the processing circuitry, at least when storage of data obtained in response to the first read request in a cache of the processing circuitry would require allocation of a new entry in the cache, prohibiting at least one response action, which is permitted for non-speculatively issued read requests specifying a target memory region of the speculation-restricted region type, from being performed before the processing circuitry has resolved whether the first read request is correct.

A method for memory allocation for a data processing apparatus, comprising:

• allocating one or more regions of memory for use by a given software process;
• and
• for each allocated region, selecting a selected region type from among a plurality of region types, and storing memory attribute data identifying the selected region type;
• in which:
• for at least one region, the selected region type comprises a speculation-restricted region type indicating that, in response to a first read request requesting that data is read from said at least one region, the data processing apparatus is to:
• at least when the first read request is non-speculatively issued by the data processing apparatus, permit a subsequent read request to be serviced using data obtained in response to the first read request;
• and
• when the first read request is speculatively issued by the data processing apparatus, at least when storage of data obtained in response to the first read request in a cache of the data processing apparatus would require allocation of a new entry in the cache, prohibit at least one response action from being performed before the data processing apparatus has resolved whether the first read request is correct, where said at least one response action is permitted for non-speculatively issued read requests specifying a target memory region of the speculation-restricted region type.