Abstract: A method for executing an executable file. The method includes executing instructions in the executable file by a first process, receiving a write request from a second process to write to the executable file, generating an anonymous file from the executable file in response to the write request, executing the anonymous file by the first process, and accessing the executable file by the second process.

Abstract: A method for executing an executable file. The method includes executing instructions in the executable file by a first process, receiving a write request from a second process to write to the executable file, generating an anonymous file from the executable file in response to the write request, executing the anonymous file by the first process, and accessing the executable file by the second process.

Abstract: A method for executing an executable file. The method includes executing instructions in the executable file by a first process, receiving a write request from a second process to write to the executable file, generating an anonymous file from the executable file in response to the write request, executing the anonymous file by the first process, and accessing the executable file by the second process.

Abstract: A method for executing an executable file. The method includes executing instructions in the executable file by a first process, receiving a write request from a second process to write to the executable file, generating an anonymous file from the executable file in response to the write request, executing the anonymous file by the first process, and accessing the executable file by the second process.

Abstract: A method for securely accessing an executable file object includes a step in which a request from the target process to access the executable file object is received by an operating system component, and the object is examined for validity before access is allowed. For objects that cannot be validated, the process is run with privileges bounded by the privilege cap, if the privilege cap permits execution of the object.

Abstract: A method for executing an executable file. The method includes executing instructions in the executable file by a first process, receiving a write request from a second process to write to the executable file, generating an anonymous file from the executable file in response to the write request, executing the anonymous file by the first process, and accessing the executable file by the second process.

Abstract: A method for validating program execution. The method involves identifying a program from a second computer system, obtaining, by a first computer system, a first copy of a page for a file of the program from a second computer system, calculating a hash value for the first copy, storing the first copy in a local memory of the first computer system, storing the hash value for the first copy, and executing the program on the first computer system, where the first copy is removed from the local memory during execution of the program. The method further involves obtaining a second copy of the page from the second computer system, calculating a hash for the second copy, determining whether the hash value for the first copy is equal to the hash value for the second copy, and performing an appropriate action in response to the determination.

Abstract: A method for executing an executable file. The method includes executing instructions in the executable file by a first process, receiving a write request from a second process to write to the executable file, generating an anonymous file from the executable file in response to the write request, executing the anonymous file by the first process, and accessing the executable file by the second process.

Abstract: A method for validating program execution. The method involves identifying a program from a second computer system, obtaining, by a first computer system, a first copy of a page for a file of the program from a second computer system, calculating a hash value for the first copy, storing the first copy in a local memory of the first computer system, storing the hash value for the first copy, and executing the program on the first computer system, where the first copy is removed from the local memory during execution of the program. The method further involves obtaining a second copy of the page from the second computer system, calculating a hash for the second copy, determining whether the hash value for the first copy is equal to the hash value for the second copy, and performing an appropriate action in response to the determination.

Abstract: A method for securely accessing an executable file object includes a step in which a request from the target process to access the executable file object is received by an operating system component, and the object is examined for validity before access is allowed. For objects that cannot be validated, the process is run with privileges bounded by the privilege cap, if the privilege cap permits execution of the object.

Abstract: A data structure extension system for dynamically adding extensions to existing data structures without interfering with underlying code. The data structure extension system includes logic that allows a programmer to “privately” extend fields of existing entries in data structures in the operating system's kernel without interfering with the functionality of the overall data structure for other applications. An extension pointer disposed in the data structure associates each entry of the data structures extended with a respective extension table. The extension table allows for the dynamic addition of non-intefering interfering fields to the data structures. Each extension table entry has corresponding data stored in an external storage unit.

Abstract: The present invention provides a process scheduler or dispatcher for a multiprocessor system for real time applications. This embodiment of the present invention proposes a dispatcher model that maintains a dispatch queue for each processor and a separate global dispatch queue for unbound higher priority real time threads. A processor has its own queue and a dispatcher. Each queue has a separate schedule lock associated with it to protect scheduling operations. A processor's dispatcher selects a thread for execution from one of the queues in the system as a candidate thread to execute. When a candidate thread is selected for execution, the processor proceeds to verify against threads in the global real time queue and the processor's own dispatch queue to select a highest priority runnable thread in the system. Thus, the present invention allows the dispatcher to prevent race conditions and minimize lock contention while assuring that high-priority threads are dispatched as quickly as possible.

Abstract: A data structure extension system for dynamically adding extensions to existing data structures without interfering with underlying code. The data structure extension system includes logic that allows a programmer to “privately” extend fields of existing entries in data structures in the operating system's kernel without interfering with the functionality of the overall data structure for other applications. An extension pointer disposed in the data structure associates each entry of the data structures extended with a respective extension table. The extension table allows for the dynamic addition of on-interfering fields to the data structures. Each extension table entry has corresponding data stored in an external storage unit.

Abstract: The present invention provides a process scheduler or dispatcher for a multiprocessor system for real time applications. This embodiment of the present invention proposes a dispatcher model that maintains a dispatch queue for each processor and a separate global dispatch queue for unbound higher priority real time threads. A processor has its own queue and a dispatcher. Each queue has a separate schedule lock associated with it to protect scheduling operations. A processor's dispatcher selects a thread for execution from one of the queues in the system as a candidate thread to execute. When a candidate thread is selected for execution, the processor proceeds to verify against threads in the global real time queue and the processor's own dispatch queue to select a highest priority runnable thread in the system. Thus, the present invention allows the dispatcher to prevent race conditions and minimize lock contention while assuring that high-priority threads are dispatched as quickly as possible.

Abstract: In a microcoded data processor, an instruction is provided which enables the microaddress for the micromachine to be externally specified. By way of this instruction, the processor may be directed to execute special microcoded routines otherwise unavailable during normal execution. These special microcoded routines may perform useful functions such as testing in an expeditious manner portions of the circuitry of the processor which would otherwise be difficult to test. For example, the functionality of regular structures such as instruction decoding and control programmable logic arrays (PLA's) may either be gated directly out to the tester or internally analyzed before the accumulated results are presented to the tester. On-board instruction caches may also be efficiently exercised to verify that the tag portion properly determines "hits" and "misses", and that the actual instruction cache portion functions accurately.

Abstract: A data processor communicates with a peripheral device and selectively sets breakpoints with minimal overhead. The data processor utilizes an instruction register to store instructions to be executed. Control means communicate with the peripheral device to selectively set a breakpoint in a software program. When repetitions of the breakpoint are encountered, an exception handler is only executed at the desired breakpoint to minimize overhead. A control portion of the processor selectively receives a breakpoint instruction and stores the breakpoint instruction in the instruction register.

Abstract: A data processor capable of automatically storing in an external memory all essential information relating to the internal state thereof upon the detection of an access fault during instruction execution. Upon correction of the cause of the fault, the data processor automatically retrieves the stored state information and restores the state thereof in accordance with the retrieved state information. The data processor then resumes execution of the instruction. The faulted access may be selectively rerun upon the resumption of instruction execution. Means are provided to verify that the retrieved state information is valid.

Abstract: A data processor capable of automatically storing in an external memory all essential information relating to the internal state thereof upon the detection of an access fault during instruction execution. Upon correction of the cause of the fault, the data processor automatically retrieves the stored state information and restores the state thereof in accordance with the retrieved state information. The data processor then resumes execution of the instruction. The faulted access may be selectively rerun upon the resumption of instruction execution. Means are provided to verify that the retrieved state information is valid.

Abstract: A data processor capable of automatically storing in an external memory all essential information relating to the internal state thereof upon the detection of an access fault during instruction execution. Upon correction of the cause of the fault, the data processor automatically retrieves the stored state information and restores the state thereof in accordance with the retrieved state information. The data processor then resumes execution of the instruction. The faulted access may be selectively rerun upon the resumption of instruction execution. Means are provided to verify that the retrieved state information is valid.

Abstract: A memory management unit of use in a memory management system. The memory management unit selectively maps a logical address to a respective physical address in accordance with a selected one of a plurality of segment descriptors, each of which defines a logical-to-physical address mapping and a range of address spaces for which such mapping is valid. The mapping is achieved using an improved associative memory circuit. Means are provided to detect mapping conflicts between new segment descriptors and segment descriptors already stored, and to prevent the storage of such conflicting segment descriptors. A method and circuit are provided to coordinate the parallel operation of a plurality of the memory management units or the like.