Dynamic software code instrumentation method and system
View Patent ↗A method and system of monitoring code as it is executed by a target processor is provided for debugging, etc. Standardized software code function preamble and postamble instructions are dynamically replaced with instructions that will generate a predetermined exception. The exception generates a branch to a conventional exception vector table. An exception routine is inserted into the vector table, and includes instruction(s) to disable the data and/or address caches. Subsequent instructions in the vector table execute the replaced preamble instruction and, with or without re-enabling the cache, branch back to the address of the program code immediately following the faulted preamble address. Instructions of the function executed while cache is disabled are executed on the bus where they are visible, as opposed to within cache.
1. A system comprising:
a target having a bus and a cache;
an emulator coupled to the target for monitoring software code being executed in the target, the emulator including:
an instruction locating module to search a range of addresses within the software code to identify a desired instruction;
an instruction replacement module to replace the desired instruction with an exception-generating instruction; and
a vector table instrumentation module to insert an exception routine into an exception vector table, the exception routine having a cache-disabling instruction and a branch instruction branching to an address of the software code disposed subsequent to the exception-generating instruction,
wherein the system adds no additional instructions to the software code being executed in the target.
2. The system of claim 1 , wherein the exception routine further comprises a cache re-enabling instruction.
3. The system of claim 1 , wherein the exception routine has a Data Cache-disabling instruction.
4. The system of claim 1 , wherein the exception routine has an Instruction Cache-disabling instruction.
5. The system of claim 1 , wherein the emulator is configured to effect a plurality of user-selectable operations selected from the group consisting of:
indicating entry and exit of a function;
indicating entry and exit of a function and tracing execution of a function;
indicating entry and exit of a function, tracing execution of the function, and indicating entry and exit and tracing execution of other functions called by the function; and
indicating Entry and Exit of a function, tracing execution of the function, and indicating Entry and Exit without tracing execution of other functions called by the function.