Oracle America, Inc.

Sun Microsystems, Inc.

Oracle International Corporation

Graham Ricketson Murphy

John Gregory Favor

Joseph Byron Rowlands

Paul G Chan

Marc R Tremblay

Zoran Radovic

Frank C Chiu

Paul Joseph Jordan

John Johnson

Darryl J Gove

Bharat Daga

Systems and methods for efficient memory corruption detection in a processor. A processor detects a first data structure is to be allocated in a physical memory. The physical memory may be a DRAM with a spare bank of memory reserved for a hardware failover mechanism. Either the processor or an operating system (OS) determines a first version number corresponding to the first data structure. During initialization of the first data structure, the first version number may be stored in a first location in the spare bank. The processor receives from the OS a pointer holding the first version number. When the processor executes memory access operations targeting the first data structure, the processor compares the first version number with a third version number stored in a location in the physical memory indicated by the memory access address. The processor may set a trap in response to determining a mismatch.

Efficient storage of memory version data

Systems and methods for providing additional instructions for supporting efficient memory corruption detection in a processor. A physical memory may be a DRAM with a spare bank of memory reserved for a hardware failover mechanism. Version numbers associated with data structures allocated in the memory may be generated so that version numbers of adjacent data structures are different. A processor determines that a fetched instruction is a memory access instruction corresponding to a first data structure within the memory. For instructions that are not a version update instruction, the processor compares the first version number and second version number stored in a location in the memory indicated by the generated address and flags an error if there is a mismatch. For version update instructions, the processor performs a memory access operation on the second version number with no comparison check.

Instructions to set and read memory version information

The disclosed embodiments provide a system that uses unused bits in a memory pointer. During operation, the system determines a set of address bits in a address space that will not be needed for addressing purposes during program operation. Subsequently, the system stores data associated with the memory pointer in this set of address bits. The system masks this set of address bits when using the memory pointer to access the memory address associated with the memory pointer. Storing additional data in unused pointer bits can reduce the number of memory accesses for a program and improve program performance and/or reliability.

Method and apparatus for using unused bits in a memory pointer

An embodiment of the present invention includes a circuit for tracking memory operations with trace-based execution. Each trace includes a sequence of operations that includes zero or more of the memory operations. At least some of the active memory operations access the memory in an execution order that is different from the program order. The circuit includes a first memory that caches data accessed by the memory operations. This memory is partitioned into N banks. Checkpoint entries, which are stored in a second memory also partitioned into N banks, are associated with each trace. Each entry refers to a checkpoint location in the first memory. A sub-circuit receives rollback requests and responds by overwriting checkpoint locations. Each of the N memory units consisting of a bank in the first memory and the corresponding bank in the second memory may be rolled back independently and concurrently with other memory units.

Cache rollback acceleration via a bank based versioning cache ciruit

This invention includes a circuit for tracking memory operations with trace-based execution. Each trace includes a sequence of operations that includes zero or more of the memory operations. The memory operations being executed form a set of active memory operations that have a predefined program order among them and corresponding ordering constraints. At least some of the active memory operations access the memory in an execution order that is different from the program order. Checkpoint entries are associated with each trace. Each entry refers to a checkpoint location. Memory operation ordering entries correspond to each one of the active memory operations. Violations of the ordering constraints result in overwriting the checkpoint locations associated with the selected trace as well as the checkpoint locations associated with traces that are younger than the selected trace.

Data cache rollbacks for failed speculative traces with memory operations

A circuit for tracking memory operations with trace-based execution is disclosed. Each trace includes a sequence of operations that includes zero or more of the memory operations. The memory operations being executed form a set of active memory operations that have a predefined program order among them. At least some of the active memory operations access the memory in an execution order that is different from the program order. Checkpoint entries are associated with each trace. Each entry refers to a checkpoint location. Executing one of the active memory operations updates a checkpoint location. During the operation of the circuit, none of the operations of a given trace has any effect on the execution unit's architectural state prior to committing that trace. Each trace becomes eligible for commitment after all operations in the trace complete executing. After the trace is committed, all of the checkpoint entries associated with the trace are invalidated.

Trace based deallocation of entries in a versioning cache circuit

A processor includes a circuit for tracking memory operations with trace-based execution. Each trace includes a sequence of operations that includes zero or more of the memory operations. The memory operations being executed form a set of active memory operations that have a predefined program order among them. At least some of the active memory operations access the memory in an execution order that is different from the program order. During the operation of the circuit, none of the operations of a given trace has any effect on the execution unit's architectural state prior to committing that trace. Each trace becomes eligible for commitment after all operations in the trace complete executing. The circuit also includes a sub-circuit that holds memory operation ordering information corresponding to the active memory operations. The sub-circuit detects violations of ordering constraints. After each trace is committed, the sub-circuit invalidates all of the memory operation ordering information associated with the trace.

Memory ordering queue/versioning cache circuit

An embodiment of the present invention includes a circuit for tracking memory operations with trace-based execution. Each trace includes a sequence of operations that includes zero or more of the memory operations. The memory operations being executed form a set of active memory operations that have a predefined program order among them and corresponding ordering constraints. At least some of the active memory operations access the memory in an execution order that is different from the program order. Checkpoint entries are associated with each trace. Violations of the ordering constraints may be signaled too late to prevent an update of the cached data associated with the memory operations. A sub-circuit detects this condition and invalidates the checkpoint locations indicated by the checkpoint entries associated with the trace experiencing the violation and all younger traces.

Checking for a memory ordering violation after a speculative cache write

An embodiment of the present invention includes a circuit for tracking memory operations with trace-based execution. Each trace includes a sequence of operations that includes zero or more of the memory operations. The memory operations being executed form a set of active memory operations that have a predefined program order among them and corresponding ordering constraints. At least some of the active memory operations access the memory in an execution order that is different from the program order. Checkpoint entries are associated with each trace. When a memory operation attempts to update a cache line that may not be updated, the circuit attempts to upgrade the cache line. If this fails, a rollback request is generated that indicates the trace involved. The checkpoint locations associated with the indicated trace are overwritten along with those locations associated with all younger traces.

Rolling back a speculative update of a non-modifiable cache line

This invention includes a circuit for tracking memory operations with trace-based execution. Each trace includes a sequence of operations that includes zero or more of the memory operations. Traces execute atomically and become eligible for commitment after all the operations in the trace have executed. The memory operations being executed form a set of active memory operations that have a predefined program order among them and corresponding ordering constraints. At least some of the active memory operations access the memory in an execution order that is different from the program order. Checkpoint entries are associated with each trace. Each entry refers to a checkpoint location. Memory operation ordering entries correspond to each one of the active memory operations. Rollback requests result in overwriting the checkpoint locations associated with the selected trace as well as the checkpoint locations associated with traces that are younger than the selected trace.

Trace based rollback of a speculatively updated cache

An embodiment of the present invention includes a circuit for tracking memory operations with trace-based execution. Each trace includes a sequence of operations that includes zero or more of the memory operations. The memory operations being executed form a set of active memory operations that have a predefined program order among them and corresponding ordering constraints. At least some of the active memory operations access the memory in an execution order that is different from the program order. Checkpoint entries are associated with each trace. There is a one-to-one correspondence between checkpoint entries and memory operation ordering entries. Each checkpoint entry refers to a checkpoint location. Rollback requests cause the circuit to overwrite checkpoint entries associated with the corresponding trace.

Memory ordering queue tightly coupled with a versioning cache circuit

The present invention provides an instruction fetch unit aligner. In one embodiment, an apparatus for an instruction fetch unit aligner includes selection logic for selecting a non-power of two size instruction from power of two size instruction data, and control logic for controlling the selection logic.

Instruction fetch unit aligner for a non-power of two size VLIW instruction

The present invention provides dual in-line buffers for an instruction fetch unit. In one embodiment, an apparatus for a microprocessor includes an instruction cache unit that stores power of two size instruction cache lines, and dual in-line buffers of an instruction fetch unit connected to the instruction cache unit, in which the dual in-line buffers store power of two size instruction cache lines fetched from the instruction cache unit, and the fetched instruction cache lines include a non-power of two size instruction.

Dual in-line buffers for an instruction fetch unit

The present invention provides an efficient method for fetching instructions having a non-power of two size. In one embodiment, a method for fetching instructions having a non-power of two size includes fetching a first instruction cache line having a power of two size for storage in a first line buffer of an instruction fetch unit of a microprocessor, fetching a second instruction cache line having a power of two size for storage in a second line buffer of the instruction fetch unit, and extracting and aligning instruction data stored in the first line buffer and the second line buffer to provide an instruction having a non-power of two size.

Growing community of inventors

Sunnyvale, CA, United States of America

Graham Ricketson Murphy