Abstract: Fine-grained detection of data modification of original data is provided by associating separate guard bits with granules of memory storing original data from which translated data has been obtained. The guard bits indicating whether the original data stored in the associated granule is protected for data coherency. The guard bits are set and cleared by special-purpose instructions. Responsive to attempting access to translated data obtained from the original data, the guard bit(s) associated with the original data is checked to determine whether the guard bit(s) fail to indicate coherency of the original data, and if so, discarding of the translated data is initiated to facilitate maintaining data coherency between the original data and the translated data.

Abstract: A method, system and computer program product is provided for emulating two or more processes for executing a source application, comprising: providing virtual trampoline memory whereby each emulated process has a respective private trampoline memory; providing shared code heap memory, wherein each emulated process only sees the code heap and its respective private trampoline memory; fetching a fragment of source instructions from the application; generating equivalent target instructions for writing to the code heap, the fragment of target instruction being indexed by its physical address in the code heap; generating, for each jump instruction in the fragment, a jump to a slot in the virtual trampoline memory; and writing a trap in each private trampoline slot, each trap adapted to be replaced by a jump to a physical address in the code heap corresponding the start of the same or a different target instruction fragment.

Abstract: This invention relates to a method and framework for invisible code rewriting. A method, system, and computer program for allowing modification of executable program code in a computer platform comprising: providing a virtual address space on the platform, said virtual space comprising a first and second address space; identifying a program into the first address space; identifying an enhancement to the program; copying the program into the second address space; modifying the program copy in the second address space to provide the enhancement; and configuring the platform to execute the program and executing the enhanced program in second address space.

Abstract: Performing storage writes in a mirrored virtual machine system by receiving a state of a primary virtual machine during execution of an application, wherein the primary virtual machine runs on a first physical machine and a secondary virtual machine runs on a second physical machine, wherein the state is captured by checkpointing, and the primary virtual machine is configured to write data to a first block and concurrently write the data to a write buffer on the secondary virtual machine. The method also includes storing a copy of data within a second block to a rollback buffer for the secondary virtual machine, in response to identifying a checkpoint in the application, merging the rollback buffer with the write buffer, in response to detecting a failover, writing a copy of the rollback buffer to the disk storage, and continuing execution on the secondary virtual machine from the last checkpoint.

Abstract: A dynamic binary translator apparatus, method and program for translating a first block of binary computer code intended for execution in a subject execution environment having a first memory of one page size into a second block for execution in a second execution environment having a second memory of another page size, comprising a redirection page mapper responsive to a page characteristic of the first memory for mapping an address of the first memory to an address of the second memory; a memory fault behaviour detector operable to detect memory faulting during execution of the second block and to accumulate a fault count to a trigger threshold; and a regeneration component responsive to the fault count reaching the trigger threshold to discard the second block and cause the first block to be retranslated with its memory references remapped by a page table walk.

Abstract: A partitioning technique utilized by a translator to divide the subject code space into regions, referred to hereafter as partitions, where each partition contains a distinct set of basic blocks of subject code and corresponding target code. The partitioning technique divides the translator's representation of subject code and subject code translations into non-overlapping regions of subject memory. In this manner, when the subject program modifies subject code, only those partitions actually affected by the self-modifying code need be discarded and all translations in unaffected partitions can be kept. This partitioning technique is advantageous in limiting the amount of target code that must be retranslated in response to self-modifying code operation. In another process, the partitioning technique allows multithreaded subject programs that also involve self-modifying code to perform code modification in a thread-safe manner.

Abstract: Subject program code is translated to target code in basic block units at run-time in a process wherein translation of basic blocks is interleaved with execution of those translations. A shared code cache mechanism is added to persistently store subject code translations, such that a translator may reuse translations that were generated and/or optimized by earlier translator instances.

Abstract: In program code conversion, particularly dynamic binary translation, subject code 17 is translated into target code 21 through a translator 19 for execution on a target processor 13. Selected portions of subject code, such as library functions SFuncA 172, are replaced by instead executing a portion of native code such as a native function NFuncA 282. The native function is native to the target processor 13. The method further includes executing a subject code portion such as a subject function SFuncB 173 in place of a native code portion such library function NFuncB 283. This reverse binding technique substitutes subject code for selected portions of the native code, particularly native library functions in order to keep control within the translator 19. This helps to maintain an accurate subject state in the translator 19, amongst other advantages.

Abstract: A native binding technique is provided for inserting calls to native functions during translation of subject code to target code, such that function calls in the subject program to subject code functions are replaced in target code with calls to native equivalents of the same functions. Parameters of native function calls are transformed from target code representations to be consistent with native code representations, native code calling conventions, and native function prototypes.

Abstract: A native binding technique is provided for inserting calls to native functions during translation of subject code to target code, such that function calls in the subject program to subject code functions are replaced in target code with calls to native equivalents of the same functions. Parameters of native function calls are transformed from target code representations to be consistent with native code representations, native code calling conventions, and native function prototypes.

Abstract: An emulator allows subject code written for a subject processor having subject processor registers and condition code flags to run in a non-compatible computing environment. The emulator identifies and records parameters of instructions in the subject code that affect status of the subject condition code flags. Then, when an instruction in the subject code is encountered, such as a branch or jump, that uses the flag status to make a decision, the flag status is resolved from the recorded instruction parameters. Advantageously, emulation overhead is substantially reduced.

Abstract: An emulator (30) allows subject code (10) written for a subject processor (12) having subject processor registers (14) and condition code flags (16) to run in a non-compatible computing environment (2). The emulator (30) identifies and records parameters of instructions in the subject code (10) that affect status of the subject condition code flags (16). Then, when an instruction in the subject code (10) is encountered, such as a branch or jump, that uses the flag status to make a decision, the flag status is resolved from the recorded instruction parameters. Advantageously, emulation overhead is substantially reduced.

Abstract: In program code conversion, particularly dynamic binary translation, subject code 17 is translated into target code 21 through a translator 19 for execution on a target processor 13. Selected portions of subject code, such as library functions SFuncA 172, are replaced by instead executing a portion of native code such as a native function NFuncA 282. The native function is native to the target processor 13. The method further includes executing a subject code portion such as a subject function SFuncB 173 in place of a native code portion such library function NFuncB 283. This reverse binding technique substitutes subject code for selected portions of the native code, particularly native library functions in order to keep control within the translator 19. This helps to maintain an accurate subject state in the translator 19, amongst other advantages.

Abstract: A partitioning technique utilized by a translator to divide the subject code space into regions, referred to hereafter as partitions, where each partition contains a distinct set of basic blocks of subject code and corresponding target code. The partitioning technique divides the translator's representation of subject code and subject code translations into non-overlapping regions of subject memory. In this manner, when the subject program modifies subject code, only those partitions actually affected by the self-modifying code need be discarded and all translations in unaffected partitions can be kept. This partitioning technique is advantageous in limiting the amount of target code that must be retranslated in response to self-modifying code operation.

Abstract: A native binding technique is provided for inserting calls to native functions during translation of subject code to target code, such that function calls in the subject program to subject code functions are replaced in target code with calls to native equivalents of the same functions. Parameters of native function calls are transformed from target code representations to be consistent with native code representations, native code calling conventions, and native function prototypes.

Abstract: Subject program code is translated to target code in basic block units at run-time in a process wherein translation of basic blocks is interleaved with execution of those translations. A shared code cache mechanism is added to persistently store subject code translations, such that a translator may reuse translations that were generated and/or optimized by earlier translator instances.

Abstract: An emulator (30) allows subject code (10) written for a subject processor (12) having subject processor registers (14) and condition code flags (16) to run in a non-compatible computing environment (2). The emulator (3) identifies and records parameters of instructions in the subject code (10) that affect status of the subject condition code flags (16). Then, when an instruction in the subject code (10) is encountered, such as a branch or jump, that uses the flag status to make a decision, the flag status is resolved from the recorded instruction parameters. Advantageously, emulation overhead is substantially reduced.