230 results about "Binary translation" patented technology

Mechanisms have been developed for securing computational systems against certain forms of attack. In particular, it has been discovered that, by maintaining and propagating taint status for memory locations in correspondence with information flows of instructions executed by a computing system, it is possible to provide a security response if and when a control transfer (or other restricted use) is attempted based on tainted data. In some embodiments, memory management facilities and related exception handlers can be exploited to facilitate taint status propagation and / or security responses. Taint tracking through registers of a processor (or through other storage for which access is not conveniently mediated using a memory management facility) may be provided using an instrumented execution mode of operation. For example, the instrumented mode may be triggered by an attempt to propagate tainted information to a register. In some embodiments, an instrumented mode of operation may be more generally employed. For example, data received from an untrusted source or via an untrusted path is often transferred into a memory buffer for processing by a particular service, routine, process, thread or other computational unit. Code that implements the computational unit may be selectively executed in an instrumented mode that facilitates taint tracking. In general, instrumented execution modes may be supported using a variety of techniques including a binary translation (or rewriting) mode, just-in-time (JIT) compilation / re-compilation, interpreted mode execution, etc. Using an instrumented execution mode and / or exception handler techniques, modifications to CPU hardware can be avoided if desirable.

A sequence of input language (IL) instructions of a guest system is converted, for example by binary translation, into a corresponding sequence of output language (OL) instructions of a host system, which executes the OL instructions. In order to determine the return address after any IL call to a subroutine at a target entry address P, the corresponding OL return address is stored in an array at a location determined by an index calculated as a function of P. After completion of execution of the OL translation of the IL subroutine, execution is transferred to the address stored in the array at the location where the OL return address was previously stored. A confirm instruction block is included in each OL call site to determine whether the transfer was to the correct or incorrect call site, and a back-up routine is included to handle the cases of incorrect call sites.