Method to switch the lock-bits combination used to lock a page table entry upon receiving system reset exceptions
First Claim
1. A method in a data processing system for changing a lock-bits combination in a software lock to resolve a deadlock of a particular subset of a memory region within the data processing system, comprising:
- receiving a system reset exception;
identifying the lock-bits combination to use in the software lock, wherein the lock-bits combination is identified based on a value of system reset exception occurrence bits retrieved from a memory location; and
updating the software lock that is maintained in another memory location with the identified lock-bits combination, wherein updating the software lock allows the data processing system to resolve the deadlock of the particular subset of the memory region without resetting the software lock to an initial state.
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Abstract
A method, system, and computer instructions for changing the lock-bits combination used to lock a resource upon receiving a system reset exception. The present invention forces the software to use different lock-bits combinations based on the number of occurrences of system reset exceptions. When a system reset exception is received, a system reset exception bit value in a special purpose register is updated based on the history of system reset exception occurrences. Based on the updated value in the system reset exception bit, the lock-bits combination for locking a resource is changed to allow the data processing system to reuse the resource with bad lock-bits. In this manner, the deadlocked resource is resolved, and a processor is not able to obtain an indefinitely held lock on system resources caused by system reset exceptions.
31 Citations
36 Claims
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1. A method in a data processing system for changing a lock-bits combination in a software lock to resolve a deadlock of a particular subset of a memory region within the data processing system, comprising:
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receiving a system reset exception; identifying the lock-bits combination to use in the software lock, wherein the lock-bits combination is identified based on a value of system reset exception occurrence bits retrieved from a memory location; and updating the software lock that is maintained in another memory location with the identified lock-bits combination, wherein updating the software lock allows the data processing system to resolve the deadlock of the particular subset of the memory region without resetting the software lock to an initial state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A data processing system for changing a lock-bits combination in a software lock to resolve a deadlock of a particular subset of a memory region within the data processing system, comprising:
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receiving means for receiving a system reset exception; identifying means for identifying the lock-bits combination to use in the software lock, wherein the lock-bits combination is identified based on a value of system reset exception occurrence bits retrieved from a memory location; and updating means for updating the software lock that is maintained in another memory location with the identified lock-bits combination, wherein updating the software lock allows the data processing system to resolve the deadlock of the particular subset of the memory region without resetting the software lock to an initial state. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A computer program product encoded in a tangible computer readable medium for changing a lock-bits combination in a software lock to resolve a deadlock of a particular subset of a memory region within the data processing system, comprising:
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first instructions for receiving a system reset exception; second instructions for identifying the lock-bits combination to use in the software lock, wherein the lock-bits combination is identified based on a value of system reset exception occurrence bits retrieved from a memory location; and third instructions for updating the software lock that is maintained in another memory location with the identified lock-bits combination, wherein updating the software lock allows the data processing system to resolve the deadlock of the particular subset of the memory region without resetting the software lock to an initial state. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification