Non-translatable storage protection control system
First Claim
1. A protectable storage system for a main memory comprised of physical blocks, the blocks having respective address sub-ranges within the overall physical address range of the main memory, comprisingkey register means having at least an instruction access key register section and an operand access key register section,storage access request means in a processor for sensing and signalling each type of storage access request made by the processor, the detectable types of request signals including an instruction fetch signal and at least one type of operand access signal, each request signal being for accessing a specified physical address in the main memory, storage request selection means for granting an instruction fetch or operand access request signal to have access to storage,active key selection means being actuated by a granted instruction fetch request signal or a granted operand access request signal to outgate the content of a corresponding key register section as an active accesss key, the active access key being associated with the specified physical address corresponding to the active access key,a storage key stack comprised of a plurality of storage key registers respectively assigned to the blocks in the main memory, each register having a key field for containing a storage key assigned to the respective block,means for outputting a storage key in a selected storage key register in the stack, the register being selected by means of a high-order field in a specified physical address which is the address providing the request signal actuating the active key selection means to outgate the active access key,a comparator means comparing the outputted storage key from the selected storage key register with the active access key outputted by the active key selection means to provide a compare-equal signal when the compared keys are equal, and a non-compare signal when they are not equal,whereby the access at the specified address within a key protected sub-range may be allowed if a compare-equal signal is outputted by the comparator means.
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Abstract
Combines a storage protect key stack with an access key register (AKR) and active access key (AAK) select circuits. Storage key entries in the stack correspond to the physical blocks in main memory. This combination can provide storage protection for different storage access types within address sub-ranges in the main memory associated with respective access keys. The sub-ranges are blocks of addresses within the full range of addresses of the physical memory. The protect key operation applies to physical addresses, and it obtains system addressing compatibility with an address translation operation using the same access keys as address keys with program logical addresses.
Special features include a shared protect key, which need not be loaded in the AKR, to make specified sub-range(s) shareable by all users of the system, so that any user can access the blocks in memory associated with the shared protect key. For I/O accesses, an override is provided which ignores any read-only control of any memory block to which an I/O access is requested. Supervisor accesses can be made in all key areas, regardless of the AAK, the protect keys, or the read-only flag bits.
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Citations
6 Claims
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1. A protectable storage system for a main memory comprised of physical blocks, the blocks having respective address sub-ranges within the overall physical address range of the main memory, comprising
key register means having at least an instruction access key register section and an operand access key register section, storage access request means in a processor for sensing and signalling each type of storage access request made by the processor, the detectable types of request signals including an instruction fetch signal and at least one type of operand access signal, each request signal being for accessing a specified physical address in the main memory, storage request selection means for granting an instruction fetch or operand access request signal to have access to storage, active key selection means being actuated by a granted instruction fetch request signal or a granted operand access request signal to outgate the content of a corresponding key register section as an active accesss key, the active access key being associated with the specified physical address corresponding to the active access key, a storage key stack comprised of a plurality of storage key registers respectively assigned to the blocks in the main memory, each register having a key field for containing a storage key assigned to the respective block, means for outputting a storage key in a selected storage key register in the stack, the register being selected by means of a high-order field in a specified physical address which is the address providing the request signal actuating the active key selection means to outgate the active access key, a comparator means comparing the outputted storage key from the selected storage key register with the active access key outputted by the active key selection means to provide a compare-equal signal when the compared keys are equal, and a non-compare signal when they are not equal, whereby the access at the specified address within a key protected sub-range may be allowed if a compare-equal signal is outputted by the comparator means.
Specification