Abstract:
A processor and method are described for managing different privilege levels associated with different types of program code, including binary translation program code. For example, one embodiment of a method comprises entering into one of a plurality of privilege modes responsive to detecting the execution of a corresponding one of a plurality of different types of program code including native executable program code, translated executable program code, and binary translation program code. In one embodiment, the binary translation program code includes sub-components each of which are associated with a different privilege level for improved security.

Description:
BACKGROUND 
     1. Field of the Invention 
     This invention relates generally to the field of computer processors and software. More particularly, the invention relates to an apparatus and method for securing a dynamic binary translation system. 
     2. Description of the Related Art 
     In prior binary translation implementations, the binary translation software is loaded from persistent storage such as the platform flash read only memory (ROM) into a predefined area in the system random access memory (RAM). The dynamically translated binary code is then stored in a part of the remaining system RAM, called the “Translation Cache.” The rest of the remaining memory is available for x86 software including the basic input output system (BIOS), operating system (OS) and applications. Prior solutions alternate between binary translation software execution for interpreting or translating the x86 binaries and translated code execution for executing the translated code. 
     Because prior implementations operate at single privilege level for accessing the processor resources (e.g., register states, memory regions, IO regions and the type of instructions), the binary translation memory configuration and the processor transitions between binary translation software execution and translated code execution lead to security vulnerabilities, allowing translated code to access system RAM, and maliciously modify the binary translation software. As another example, since the binary translation software code has full access to the entire memory, it can compromise data that belongs to the translator as well as translated code. These and other vulnerabilities can compromise the security of the binary translation software, or the security guarantees provided to the original translated code, or both. 
     The embodiments of the invention described herein provide techniques for mitigating some of these vulnerabilities. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present invention can be obtained from the following detailed description in conjunction with the following drawings, in which: 
         FIG. 1A  is a block diagram illustrating both an exemplary in-order pipeline and an exemplary register renaming, out-of-order issue/execution pipeline according to embodiments of the invention; 
         FIG. 1B  is a block diagram illustrating both an exemplary embodiment of an in-order architecture core and an exemplary register renaming, out-of-order issue/execution architecture core to be included in a processor according to embodiments of the invention; 
         FIG. 2  is a block diagram of a single core processor and a multicore processor with integrated memory controller and graphics according to embodiments of the invention; 
         FIG. 3  illustrates a block diagram of a system in accordance with one embodiment of the present invention; 
         FIG. 4  illustrates a block diagram of a second system in accordance with an embodiment of the present invention; 
         FIG. 5  illustrates a block diagram of a third system in accordance with an embodiment of the present invention; 
         FIG. 6  illustrates a block diagram of a system on a chip (SoC) in accordance with an embodiment of the present invention; 
         FIG. 7  illustrates a block diagram contrasting the use of a software instruction converter to convert binary instructions in a source instruction set to binary instructions in a target instruction set according to embodiments of the invention; 
         FIG. 8  illustrates a system architecture according to one embodiment of the invention; 
         FIG. 9  illustrates transitions between different modes in accordance with one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention described below. It will be apparent, however, to one skilled in the art that the embodiments of the invention may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form to avoid obscuring the underlying principles of the embodiments of the invention. 
     Exemplary Processor Architectures and Data Types 
       FIG. 1A  is a block diagram illustrating both an exemplary in-order pipeline and an exemplary register renaming, out-of-order issue/execution pipeline according to embodiments of the invention.  FIG. 1B  is a block diagram illustrating both an exemplary embodiment of an in-order architecture core and an exemplary register renaming, out-of-order issue/execution architecture core to be included in a processor according to embodiments of the invention. The solid lined boxes in  FIGS. 1A-B  illustrate the in-order pipeline and in-order core, while the optional addition of the dashed lined boxes illustrates the register renaming, out-of-order issue/execution pipeline and core. Given that the in-order aspect is a subset of the out-of-order aspect, the out-of-order aspect will be described. 
     In  FIG. 1A , a processor pipeline  100  includes a fetch stage  102 , a length decode stage  104 , a decode stage  106 , an allocation stage  108 , a renaming stage  110 , a scheduling (also known as a dispatch or issue) stage  112 , a register read/memory read stage  114 , an execute stage  116 , a write back/memory write stage  118 , an exception handling stage  122 , and a commit stage  124 . 
       FIG. 1B  shows processor core  190  including a front end unit  130  coupled to an execution engine unit  150 , and both are coupled to a memory unit  170 . The core  190  may be a reduced instruction set computing (RISC) core, a complex instruction set computing (CISC) core, a very long instruction word (VLIW) core, or a hybrid or alternative core type. As yet another option, the core  190  may be a special-purpose core, such as, for example, a network or communication core, compression engine, coprocessor core, general purpose computing graphics processing unit (GPGPU) core, graphics core, or the like. 
     The front end unit  130  includes a branch prediction unit  132  coupled to an instruction cache unit  134 , which is coupled to an instruction translation lookaside buffer (TLB)  136 , which is coupled to an instruction fetch unit  138 , which is coupled to a decode unit  140 . The decode unit  140  (or decoder) may decode instructions, and generate as an output one or more micro-operations, micro-code entry points, microinstructions, other instructions, or other control signals, which are decoded from, or which otherwise reflect, or are derived from, the original instructions. The decode unit  140  may be implemented using various different mechanisms. Examples of suitable mechanisms include, but are not limited to, look-up tables, hardware implementations, programmable logic arrays (PLAs), microcode read only memories (ROMs), etc. In one embodiment, the core  190  includes a microcode ROM or other medium that stores microcode for certain macroinstructions (e.g., in decode unit  140  or otherwise within the front end unit  130 ). The decode unit  140  is coupled to a rename/allocator unit  152  in the execution engine unit  150 . 
     The execution engine unit  150  includes the rename/allocator unit  152  coupled to a retirement unit  154  and a set of one or more scheduler unit(s)  156 . The scheduler unit(s)  156  represents any number of different schedulers, including reservations stations, central instruction window, etc. The scheduler unit(s)  156  is coupled to the physical register file(s) unit(s)  158 . Each of the physical register file(s) units  158  represents one or more physical register files, different ones of which store one or more different data types, such as scalar integer, scalar floating point, packed integer, packed floating point, vector integer, vector floating point, status (e.g., an instruction pointer that is the address of the next instruction to be executed), etc. In one embodiment, the physical register file(s) unit  158  comprises a vector registers unit, a write mask registers unit, and a scalar registers unit. These register units may provide architectural vector registers, vector mask registers, and general purpose registers. The physical register file(s) unit(s)  158  is overlapped by the retirement unit  154  to illustrate various ways in which register renaming and out-of-order execution may be implemented (e.g., using a reorder buffer(s) and a retirement register file(s); using a future file(s), a history buffer(s), and a retirement register file(s); using a register maps and a pool of registers; etc.). The retirement unit  154  and the physical register file(s) unit(s)  158  are coupled to the execution cluster(s)  160 . The execution cluster(s)  160  includes a set of one or more execution units  162  and a set of one or more memory access units  164 . The execution units  162  may perform various operations (e.g., shifts, addition, subtraction, multiplication) and on various types of data (e.g., scalar floating point, packed integer, packed floating point, vector integer, vector floating point). While some embodiments may include a number of execution units dedicated to specific functions or sets of functions, other embodiments may include only one execution unit or multiple execution units that all perform all functions. The scheduler unit(s)  156 , physical register file(s) unit(s)  158 , and execution cluster(s)  160  are shown as being possibly plural because certain embodiments create separate pipelines for certain types of data/operations (e.g., a scalar integer pipeline, a scalar floating point/packed integer/packed floating point/vector integer/vector floating point pipeline, and/or a memory access pipeline that each have their own scheduler unit, physical register file(s) unit, and/or execution cluster—and in the case of a separate memory access pipeline, certain embodiments are implemented in which only the execution cluster of this pipeline has the memory access unit(s)  164 ). It should also be understood that where separate pipelines are used, one or more of these pipelines may be out-of-order issue/execution and the rest in-order. 
     The set of memory access units  164  is coupled to the memory unit  170 , which includes a data TLB unit  172  coupled to a data cache unit  174  coupled to a level 2 (L2) cache unit  176 . In one exemplary embodiment, the memory access units  164  may include a load unit, a store address unit, and a store data unit, each of which is coupled to the data TLB unit  172  in the memory unit  170 . The instruction cache unit  134  is further coupled to a level 2 (L2) cache unit  176  in the memory unit  170 . The L2 cache unit  176  is coupled to one or more other levels of cache and eventually to a main memory. 
     By way of example, the exemplary register renaming, out-of-order issue/execution core architecture may implement the pipeline  100  as follows: 1) the instruction fetch  138  performs the fetch and length decoding stages  102  and  104 ; 2) the decode unit  140  performs the decode stage  106 ; 3) the rename/allocator unit  152  performs the allocation stage  108  and renaming stage  110 ; 4) the scheduler unit(s)  156  performs the schedule stage  112 ; 5) the physical register file(s) unit(s)  158  and the memory unit  170  perform the register read/memory read stage  114 ; the execution cluster  160  perform the execute stage  116 ; 6) the memory unit  170  and the physical register file(s) unit(s)  158  perform the write back/memory write stage  118 ; 7) various units may be involved in the exception handling stage  122 ; and 8) the retirement unit  154  and the physical register file(s) unit(s)  158  perform the commit stage  124 . 
     The core  190  may support one or more instructions sets (e.g., the x86 instruction set (with some extensions that have been added with newer versions); the MIPS instruction set of MIPS Technologies of Sunnyvale, Calif.; the ARM instruction set (with optional additional extensions such as NEON) of ARM Holdings of Sunnyvale, Calif.), including the instruction(s) described herein. In one embodiment, the core  190  includes logic to support a packed data instruction set extension (e.g., AVX1, AVX2, and/or some form of the generic vector friendly instruction format (U=0 and/or U=1), described below), thereby allowing the operations used by many multimedia applications to be performed using packed data. 
     It should be understood that the core may support multithreading (executing two or more parallel sets of operations or threads), and may do so in a variety of ways including time sliced multithreading, simultaneous multithreading (where a single physical core provides a logical core for each of the threads that physical core is simultaneously multithreading), or a combination thereof (e.g., time sliced fetching and decoding and simultaneous multithreading thereafter such as in the Intel® Hyperthreading technology). 
     While register renaming is described in the context of out-of-order execution, it should be understood that register renaming may be used in an in-order architecture. While the illustrated embodiment of the processor also includes separate instruction and data cache units  134 / 174  and a shared L2 cache unit  176 , alternative embodiments may have a single internal cache for both instructions and data, such as, for example, a Level 1 (L1) internal cache, or multiple levels of internal cache. In some embodiments, the system may include a combination of an internal cache and an external cache that is external to the core and/or the processor. Alternatively, all of the cache may be external to the core and/or the processor. 
       FIG. 2  is a block diagram of a processor  200  that may have more than one core, may have an integrated memory controller, and may have integrated graphics according to embodiments of the invention. The solid lined boxes in  FIG. 2  illustrate a processor  200  with a single core  202 A, a system agent  210 , a set of one or more bus controller units  216 , while the optional addition of the dashed lined boxes illustrates an alternative processor  200  with multiple cores  202 A-N, a set of one or more integrated memory controller unit(s)  214  in the system agent unit  210 , and special purpose logic  208 . 
     Thus, different implementations of the processor  200  may include: 1) a CPU with the special purpose logic  208  being integrated graphics and/or scientific (throughput) logic (which may include one or more cores), and the cores  202 A-N being one or more general purpose cores (e.g., general purpose in-order cores, general purpose out-of-order cores, a combination of the two); 2) a coprocessor with the cores  202 A-N being a large number of special purpose cores intended primarily for graphics and/or scientific (throughput); and 3) a coprocessor with the cores  202 A-N being a large number of general purpose in-order cores. Thus, the processor  200  may be a general-purpose processor, coprocessor or special-purpose processor, such as, for example, a network or communication processor, compression engine, graphics processor, GPGPU (general purpose graphics processing unit), a high-throughput many integrated core (MIC) coprocessor (including 30 or more cores), embedded processor, or the like. The processor may be implemented on one or more chips. The processor  200  may be a part of and/or may be implemented on one or more substrates using any of a number of process technologies, such as, for example, BiCMOS, CMOS, or NMOS. 
     The memory hierarchy includes one or more levels of cache within the cores, a set or one or more shared cache units  206 , and external memory (not shown) coupled to the set of integrated memory controller units  214 . The set of shared cache units  206  may include one or more mid-level caches, such as level 2 (L2), level 3 (L3), level 4 (L4), or other levels of cache, a last level cache (LLC), and/or combinations thereof. While in one embodiment a ring based interconnect unit  212  interconnects the integrated graphics logic  208 , the set of shared cache units  206 , and the system agent unit  210 /integrated memory controller unit(s)  214 , alternative embodiments may use any number of well-known techniques for interconnecting such units. In one embodiment, coherency is maintained between one or more cache units  206  and cores  202 -A-N. 
     In some embodiments, one or more of the cores  202 A-N are capable of multi-threading. The system agent  210  includes those components coordinating and operating cores  202 A-N. The system agent unit  210  may include for example a power control unit (PCU) and a display unit. The PCU may be or include logic and components needed for regulating the power state of the cores  202 A-N and the integrated graphics logic  208 . The display unit is for driving one or more externally connected displays. 
     The cores  202 A-N may be homogenous or heterogeneous in terms of architecture instruction set; that is, two or more of the cores  202 A-N may be capable of execution the same instruction set, while others may be capable of executing only a subset of that instruction set or a different instruction set. In one embodiment, the cores  202 A-N are heterogeneous and include both the “small” cores and “big” cores described below. 
       FIGS. 3-6  are block diagrams of exemplary computer architectures. Other system designs and configurations known in the arts for laptops, desktops, handheld PCs, personal digital assistants, engineering workstations, servers, network devices, network hubs, switches, embedded processors, digital signal processors (DSPs), graphics devices, video game devices, set-top boxes, micro controllers, cell phones, portable media players, hand held devices, and various other electronic devices, are also suitable. In general, a huge variety of systems or electronic devices capable of incorporating a processor and/or other execution logic as disclosed herein are generally suitable. 
     Referring now to  FIG. 3 , shown is a block diagram of a system  300  in accordance with one embodiment of the present invention. The system  300  may include one or more processors  310 ,  315 , which are coupled to a controller hub  320 . In one embodiment the controller hub  320  includes a graphics memory controller hub (GMCH)  390  and an Input/Output Hub (IOH)  350  (which may be on separate chips); the GMCH  390  includes memory and graphics controllers to which are coupled memory  340  and a coprocessor  345 ; the IOH  350  is couples input/output (I/O) devices  360  to the GMCH  390 . Alternatively, one or both of the memory and graphics controllers are integrated within the processor (as described herein), the memory  340  and the coprocessor  345  are coupled directly to the processor  310 , and the controller hub  320  in a single chip with the IOH  350 . 
     The optional nature of additional processors  315  is denoted in  FIG. 3  with broken lines. Each processor  310 ,  315  may include one or more of the processing cores described herein and may be some version of the processor  200 . 
     The memory  340  may be, for example, dynamic random access memory (DRAM), phase change memory (PCM), or a combination of the two. For at least one embodiment, the controller hub  320  communicates with the processor(s)  310 ,  315  via a multi-drop bus, such as a frontside bus (FSB), point-to-point interface such as QuickPath Interconnect (QPI), or similar connection  395 . 
     In one embodiment, the coprocessor  345  is a special-purpose processor, such as, for example, a high-throughput MIC processor, a network or communication processor, compression engine, graphics processor, GPGPU, embedded processor, or the like. In one embodiment, controller hub  320  may include an integrated graphics accelerator. 
     There can be a variety of differences between the physical resources  310 ,  315  in terms of a spectrum of metrics of merit including architectural, microarchitectural, thermal, power consumption characteristics, and the like. 
     In one embodiment, the processor  310  executes instructions that control data processing operations of a general type. Embedded within the instructions may be coprocessor instructions. The processor  310  recognizes these coprocessor instructions as being of a type that should be executed by the attached coprocessor  345 . Accordingly, the processor  310  issues these coprocessor instructions (or control signals representing coprocessor instructions) on a coprocessor bus or other interconnect, to coprocessor  345 . Coprocessor(s)  345  accept and execute the received coprocessor instructions. 
     Referring now to  FIG. 4 , shown is a block diagram of a first more specific exemplary system  400  in accordance with an embodiment of the present invention. As shown in  FIG. 4 , multiprocessor system  400  is a point-to-point interconnect system, and includes a first processor  470  and a second processor  480  coupled via a point-to-point interconnect  450 . Each of processors  470  and  480  may be some version of the processor  200 . In one embodiment of the invention, processors  470  and  480  are respectively processors  310  and  315 , while coprocessor  438  is coprocessor  345 . In another embodiment, processors  470  and  480  are respectively processor  310  coprocessor  345 . 
     Processors  470  and  480  are shown including integrated memory controller (IMC) units  472  and  482 , respectively. Processor  470  also includes as part of its bus controller units point-to-point (P-P) interfaces  476  and  478 ; similarly, second processor  480  includes P-P interfaces  486  and  488 . Processors  470 ,  480  may exchange information via a point-to-point (P-P) interface  450  using P-P interface circuits  478 ,  488 . As shown in  FIG. 4 , IMCs  472  and  482  couple the processors to respective memories, namely a memory  432  and a memory  434 , which may be portions of main memory locally attached to the respective processors. 
     Processors  470 ,  480  may each exchange information with a chipset  490  via individual P-P interfaces  452 ,  454  using point to point interface circuits  476 ,  494 ,  486 ,  498 . Chipset  490  may optionally exchange information with the coprocessor  438  via a high-performance interface  439 . In one embodiment, the coprocessor  438  is a special-purpose processor, such as, for example, a high-throughput MIC processor, a network or communication processor, compression engine, graphics processor, GPGPU, embedded processor, or the like. 
     A shared cache (not shown) may be included in either processor or outside of both processors, yet connected with the processors via P-P interconnect, such that either or both processors&#39; local cache information may be stored in the shared cache if a processor is placed into a low power mode. 
     Chipset  490  may be coupled to a first bus  416  via an interface  496 . In one embodiment, first bus  416  may be a Peripheral Component Interconnect (PCI) bus, or a bus such as a PCI Express bus or another third generation I/O interconnect bus, although the scope of the present invention is not so limited. 
     As shown in  FIG. 4 , various I/O devices  414  may be coupled to first bus  416 , along with a bus bridge  418  which couples first bus  416  to a second bus  420 . In one embodiment, one or more additional processor(s)  415 , such as coprocessors, high-throughput MIC processors, GPGPU&#39;s, accelerators (such as, e.g., graphics accelerators or digital signal processing (DSP) units), field programmable gate arrays, or any other processor, are coupled to first bus  416 . In one embodiment, second bus  420  may be a low pin count (LPC) bus. Various devices may be coupled to a second bus  420  including, for example, a keyboard and/or mouse  422 , communication devices  427  and a storage unit  428  such as a disk drive or other mass storage device which may include instructions/code and data  430 , in one embodiment. Further, an audio I/O  424  may be coupled to the second bus  420 . Note that other architectures are possible. For example, instead of the point-to-point architecture of  FIG. 4 , a system may implement a multi-drop bus or other such architecture. 
     Referring now to  FIG. 5 , shown is a block diagram of a second more specific exemplary system  500  in accordance with an embodiment of the present invention. Like elements in  FIGS. 4 and 5  bear like reference numerals, and certain aspects of  FIG. 4  have been omitted from  FIG. 5  in order to avoid obscuring other aspects of  FIG. 5 . 
       FIG. 5  illustrates that the processors  470 ,  480  may include integrated memory and I/O control logic (“CL”)  472  and  482 , respectively. Thus, the CL  472 ,  482  include integrated memory controller units and include I/O control logic.  FIG. 5  illustrates that not only are the memories  432 ,  434  coupled to the CL  472 ,  482 , but also that I/O devices  514  are also coupled to the control logic  472 ,  482 . Legacy I/O devices  515  are coupled to the chipset  490 . 
     Referring now to  FIG. 6 , shown is a block diagram of a SoC  600  in accordance with an embodiment of the present invention. Similar elements in  FIG. 2  bear like reference numerals. Also, dashed lined boxes are optional features on more advanced SoCs. In  FIG. 6 , an interconnect unit(s)  602  is coupled to: an application processor  610  which includes a set of one or more cores  202 A-N and shared cache unit(s)  206 ; a system agent unit  210 ; a bus controller unit(s)  216 ; an integrated memory controller unit(s)  214 ; a set or one or more coprocessors  620  which may include integrated graphics logic, an image processor, an audio processor, and a video processor; an static random access memory (SRAM) unit  630 ; a direct memory access (DMA) unit  632 ; and a display unit  640  for coupling to one or more external displays. In one embodiment, the coprocessor(s)  620  include a special-purpose processor, such as, for example, a network or communication processor, compression engine, GPGPU, a high-throughput MIC processor, embedded processor, or the like. 
     Embodiments of the mechanisms disclosed herein may be implemented in hardware, software, firmware, or a combination of such implementation approaches. Embodiments of the invention may be implemented as computer programs or program code executing on programmable systems comprising at least one processor, a storage system (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device. 
     Program code, such as code  430  illustrated in  FIG. 4 , may be applied to input instructions to perform the functions described herein and generate output information. The output information may be applied to one or more output devices, in known fashion. For purposes of this application, a processing system includes any system that has a processor, such as, for example; a digital signal processor (DSP), a microcontroller, an application specific integrated circuit (ASIC), or a microprocessor. 
     The program code may be implemented in a high level procedural or object oriented programming language to communicate with a processing system. The program code may also be implemented in assembly or machine language, if desired. In fact, the mechanisms described herein are not limited in scope to any particular programming language. In any case, the language may be a compiled or interpreted language. 
     One or more aspects of at least one embodiment may be implemented by representative instructions stored on a machine-readable medium which represents various logic within the processor, which when read by a machine causes the machine to fabricate logic to perform the techniques described herein. Such representations, known as “IP cores” may be stored on a tangible, machine readable medium and supplied to various customers or manufacturing facilities to load into the fabrication machines that actually make the logic or processor. 
     Such machine-readable storage media may include, without limitation, non-transitory, tangible arrangements of articles manufactured or formed by a machine or device, including storage media such as hard disks, any other type of disk including floppy disks, optical disks, compact disk read-only memories (CD-ROMs), compact disk rewritable&#39;s (CD-RWs), and magneto-optical disks, semiconductor devices such as read-only memories (ROMs), random access memories (RAMs) such as dynamic random access memories (DRAMs), static random access memories (SRAMs), erasable programmable read-only memories (EPROMs), flash memories, electrically erasable programmable read-only memories (EEPROMs), phase change memory (PCM), magnetic or optical cards, or any other type of media suitable for storing electronic instructions. 
     Accordingly, embodiments of the invention also include non-transitory, tangible machine-readable media containing instructions or containing design data, such as Hardware Description Language (HDL), which defines structures, circuits, apparatuses, processors and/or system features described herein. Such embodiments may also be referred to as program products. 
     In some cases, an instruction converter may be used to convert an instruction from a source instruction set to a target instruction set. For example, the instruction converter may translate (e.g., using static binary translation, dynamic binary translation including dynamic compilation), morph, emulate, or otherwise convert an instruction to one or more other instructions to be processed by the core. The instruction converter may be implemented in software, hardware, firmware, or a combination thereof. The instruction converter may be on processor, off processor, or part on and part off processor. 
       FIG. 7  is a block diagram contrasting the use of a software instruction converter to convert binary instructions in a source instruction set to binary instructions in a target instruction set according to embodiments of the invention. In the illustrated embodiment, the instruction converter is a software instruction converter, although alternatively the instruction converter may be implemented in software, firmware, hardware, or various combinations thereof.  FIG. 7  shows a program in a high level language  702  may be compiled using an x86 compiler  704  to generate x86 binary code  706  that may be natively executed by a processor with at least one x86 instruction set core  716 . The processor with at least one x86 instruction set core  716  represents any processor that can perform substantially the same functions as an Intel processor with at least one x86 instruction set core by compatibly executing or otherwise processing (1) a substantial portion of the instruction set of the Intel x86 instruction set core or (2) object code versions of applications or other software targeted to run on an Intel processor with at least one x86 instruction set core, in order to achieve substantially the same result as an Intel processor with at least one x86 instruction set core. The x86 compiler  704  represents a compiler that is operable to generate x86 binary code  706  (e.g., object code) that can, with or without additional linkage processing, be executed on the processor with at least one x86 instruction set core  716 . Similarly,  FIG. 7  shows the program in the high level language  702  may be compiled using an alternative instruction set compiler  708  to generate alternative instruction set binary code  710  that may be natively executed by a processor without at least one x86 instruction set core  714  (e.g., a processor with cores that execute the MIPS instruction set of MIPS Technologies of Sunnyvale, Calif. and/or that execute the ARM instruction set of ARM Holdings of Sunnyvale, Calif.). The instruction converter  712  is used to convert the x86 binary code  706  into code that may be natively executed by the processor without an x86 instruction set core  714 . This converted code is not likely to be the same as the alternative instruction set binary code  710  because an instruction converter capable of this is difficult to make; however, the converted code will accomplish the general operation and be made up of instructions from the alternative instruction set. Thus, the instruction converter  712  represents software, firmware, hardware, or a combination thereof that, through emulation, simulation or any other process, allows a processor or other electronic device that does not have an x86 instruction set processor or core to execute the x86 binary code  706 . 
     Method and Apparatus for Securing a Dynamic Binary Translation System 
     The embodiments described below provide stronger security for a hardware and software co-designed dynamic binary translation (BT) system using hardware, software, and firmware based security mechanisms. Unlike prior implementations which operate at single privilege level for accessing the processor resources (e.g., register states, memory regions, IO regions and the type of instructions), these embodiments operate at multiple privilege levels, thereby improving the security of the BT mechanisms and the security guarantees provided to the original translated code. 
       FIG. 8  illustrates one embodiment of a co-designed hardware and software binary translation system. The system memory  860  is divided into a native code memory space  800 , a translation cache space  810  and binary translation code space  820 . The native code memory  800  is the memory space allocated for native software such as the BIOS software, operating system and applications. In one embodiment, the native software comprises x86 program code. However, the underlying principles of the invention are not limited to any particular instruction set architecture. 
     The binary translation code  820  includes a translator component  821  that transforms a subsection  802  of an original binary  801  of the native code memory  800  into translated code  811 . In one embodiment, the subsection  802  comprises the entire original binary  801 . In one embodiment, the translated code  811  is stored in a translation cache  810 , which may be implemented as a dedicated memory space for the translated code  811 . In one embodiment, when the translated code  811  executes, it may use a scratch space  812  to store temporary values. 
     A runtime component  822  (another sub-module of the binary translation code  820 ) provides runtime services and manages memory allocation and de-allocation for the translation cache  810 . The system layer  823  is another sub-module of the binary translation code  820  that handles system-related events such as interrupts, exceptions and dispatches job requests to the rest of the binary translation modules. The interpreter  824  is an optional module employed in one embodiment in the binary translation code  820  that provides direct emulation of the original binary. 
     Although  FIG. 8  shows one translation cache  810  and one processor  830  and one piece of translated code  811 , it should be noted that the underlying principles of the invention are not so limited. For example, the translation cache  810  can contain several pieces of translated code  811 , possibly from different binaries  801 . Similarly, it is possible to have several translation caches  810  per processor  830  (e.g., one translation cache  810  per hardware thread). Other embodiments of the invention may be implemented across several processors. 
     Additionally, different embodiments of the invention may have different configurations of the system RAM  860  and the placement of the translation cache  810  and binary translation code  820 . For example, a portion of the system RAM  860  may be embedded inside the processor as embedded DRAM (EDRAM) and a portion of the EDRAM memory storage may be allocated for the translation cache  810  and the binary translation code  820 . In some configuration, the scratch space  812  may also be implemented as processor local storage. 
     Numerous security improvements are realized by the binary translation techniques described herein. Instead of operating at a single (highest) privilege level to access the processor  830  and system resources, in one embodiment, the binary translation system is operated using the following distinct operating modes, where each mode is provided with a different level of access to processor resources: 
     1. Binary translation code “supervisor” mode: In one embodiment, the system layer  823  of the binary translation code  820  runs in “supervisor” mode at the highest privilege level comprising the greatest number privileges for executing privileged instructions, blocking and handling events, modifying privileged registers, and accessing the processor and platform resources including platform memory  860 . 
     2. Binary translation code “non-supervisor” mode: In one embodiment, the translator  821  and runtime  822  components of the binary translation code  820  are executed in “non-supervisor” mode and are provided with the lowest set of privileges for handling events and accessing the processor  830  and memory  860  when performing translations of the original binary code  801 . In one embodiment, the translator  821  and runtime  822  are provided with only those privileges required to perform their respective tasks. 
     3. Translated Code Execution mode: In one embodiment, the translated code  811  runs in “translated code execution mode” at the same privilege levels provided to access the x86 memory and platform resources. In one embodiment, translated code is more trusted and provided more privileges than native execution code as translated code is execution-only code (not self-modifiable) and is produced by the binary translation code  820 . 
     4. Native Execution mode: In one embodiment, the processor runs in native execution mode when executing the native binary code  801  from native code memory  800 . In an x86 architecture, the native x86 code is provided the same operating privileges as defined by the x86 processor architecture. This mode may be optional when the binary translation system implements a full translation model (e.g., where the hardware does not provide native execution of the x86 ISA). 
     Thus, the processor  830  may provide different privileges depending on the currently executing mode. In one embodiment, binary translation logic comprising binary translation hardware extensions  831  and/or microcode  832  are implemented on the processor  830  to manage the different privilege levels. To mitigate control flow attacks, in one embodiment, the transitions among the different modes of operation are also controlled by the processor  830 . For example, the processor  830  may manage the switching from one mode to the other using hardware-controlled entry points with binary translation logic  831  or microcode  832 . 
     Transitions to “Supervisor” Mode 
     As mentioned above, portions of the binary translation code  820  operate either in either “supervisor” or “non-supervisor” mode. In one embodiment, “Supervisor” mode is used by the system layer  823  of the binary translation code and “non-supervisor” mode is used by the translator  821  and the runtime  822 . The “supervisor” mode of the binary translation code operates with the highest privilege level. While the “supervisor” mode may be more privileged than the non-supervisor mode, this does not preclude certain resources, such as memory, instructions, and registers from being used only by the translator and runtime that operate in “non-supervisor” mode. 
     The processor  830  can enter to the “supervisor” mode of the binary translation code  820  from a mode that operates at a lesser privilege level including “non-supervisor” mode and “interpreter” mode of binary translation code, the Translated Code Execution mode and Native Execution mode. It may enter the supervisor mode in response to a certain event (e.g., an interrupt) or a condition that requires attention from the system layer  823  of the binary translation code  820 . 
     In one embodiment, entry into the “supervisor” mode is controlled by hardware. Upon entry, the processor  830  context-switches to “supervisor” mode and starts executing the defined entry point of the binary translation code  820 . The binary translation code  820  may examine the state, modify the state, and possibly switch to “non-supervisor” mode and invoke the translator  821  for performing a translation task on the original binary  801 . As mentioned, in one embodiment, the supervisor mode may be used by the system layer  823  of binary translation code, and the non-supervisor mode may be used by the translator  821  and runtime  822  of the binary translation code. 
     Transitions Between “Supervisor” and “Non-Supervisor” Modes 
     Lowering the privileges for the translator  821  to “non-supervisor” mode allows the translator  821  to run with only those privileges that are essential for conducting the translation task, thereby reducing the security risk. For example, the translator  821  only needs to access the copy of the original binary, the state information of the original binary and allocated memory space for producing translated code. When the translator  821  produces the translated code  811 , it may also produce metadata and control flow information associated with the translated code  811 . The translator  821  may also embed instructions in the translated code  811  to clear the scratch space  812  or to validate the translated code  811 . Upon completion of the translation task, the translator  821  transitions back to the system layer  823 , switching from “non-supervisor” to “supervisor” mode by executing a special instruction, which enables a controlled gated entry to “supervisor” mode with the defined entry point of the system layer  823  code. 
     Based upon the metadata and control flow information the translator produced, the system layer  823  may update the processor  830  hardware structures such as the Jump Target Look-a-side buffer (JTLB) with the control flow information that enables transition between the native code execution and the translated code. The binary translation system may also update the hardware structures to detect self/cross modifying code conditions. After the binary translation system completes its tasks, it executes a special instruction to resume execution of the original binary  801  in native execution mode. 
     Special Exits from Binary Translation Code “Non-Supervisor” Mode 
     In order to minimize the transition overhead from “non-supervisor” mode in the binary translation code  820  to native execution mode, the hardware (e.g., microcode) based transition may be provided to enable direct transition back to the native execution mode from “non-supervisor” mode of the binary translation code where the hardware implements a necessary complete context operation to restore the context of the native execution. 
     Transitions Between Native and Translated Code 
     Transitions from native to translated code hardware are controlled by processor hardware such as jump target look-a-side buffer (JTLB) which, in one embodiment, provides a translated target address for a given x86 target address and enables transition to the translated code execution. Transitions from translated code back to native code are either done by a hardware/microcode mechanism or a special instruction executed by the translated code. 
       FIG. 9  provides an illustration of the different modes and their transitions according to one embodiment. At  901 , the system is operating in translated code execution mode  901  and may enter into either native code execution mode  904  or supervisor mode  902  under hardware control (e.g., via hardware-controlled entry points using binary translation logic  831  or microcode  832 ). Supervisor mode  902  may also be entered from non-supervisor mode  903  under hardware control. In addition, native code execution mode  904  may be entered from either non-supervisor mode  903  or translated code execution mode  901  via hardware control. 
     In one embodiment, a return instruction may be executed to exit supervisor mode  902  and return to the native code execution mode  904 , translated code execution mode  901 , or non-supervisor mode  903 . In one embodiment, a different variant of the instruction or the same instruction with different parameters may be executed (i.e., with each variant or set of parameters identifying a different mode of operation  901 ,  903 ,  904 ). 
     Operating Modes and Privileges 
     In one embodiment, to mitigate the security risk, the privileges of each mode are defined with the principle of least privilege. For example, the principle of least privilege requires that in a particular layer of abstraction in a computing environment, every module (e.g., process, user or program) must be able to access only that information and resources which are necessary for its legitimate purpose. 
     Additionally, the translated code execution mode may be forced to run with the same privileges as those of the original binary  801 , in order to mitigate attacks by translated code  811 . The data address space of translated code  811  may be identical to that of the original binary  801 . In one embodiment, translated code does not gain access to the code and data memory of the binary translation code  820 . Moreover, translated code is not self-modifiable and may only be modified by the translator. The protection domains provided for the original binary such as ring level protections, user/kernel mode, etc., may also be preserved for translated code execution. For example, the translated code executed at CPL3 cannot access the memory range that is only assessable by the CPL0 original code. 
     Read and write access to scratch space  812  may be implemented with special instructions that are not included in the instruction set architecture of the original binary  801 . These instructions may be inserted into translated code  811  only by the translator  821  for the purpose of conducting register allocations. The instruction address space of translated code  811  is logically separated from the instruction&#39;s and data&#39;s linear address space of the original program. Therefore, the translation cache  810  memory space is not visible and inaccessible from the original binary  801 . The protection of the physical translation cache  810  memory space from the original binary  801  may be implemented with a hardware mechanism. On any exception during translated code execution or after execution of the instruction that causes exit, the processor  830  resumes execution of the original binary  801 . 
     The following table shows an example implementation of the operating modes and given privileges in hardware software co-designed binary translation system: 
     
       
         
               
               
               
             
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 BT software 
                   
               
             
          
           
               
                   
                 Supervisor 
                 Non- 
                 Translation 
               
             
          
           
               
                   
                 X86 
                 Special 
                   
                 supervisor 
                 Memory 
               
             
          
           
               
                   
                 code 
                 data 
                 ISA 
                 code 
                 data 
                 code 
                 data 
                 code 
                 scratch 
               
               
                   
                   
               
             
          
           
               
                 BT Software 
                 R-- 
                 — 
                 Yes 
                 R-X 
                 RW- 
                 R-X 
                 RW- 
                 RW- 
                 RW- 
               
               
                 “supervisor” mode 
               
               
                 BT Software 
                 — 
                 — 
                 No 
                 — 
                 — 
                 R-W 
                 RW- 
                 — 
                 — 
               
               
                 “non-supervisor” mode 
               
               
                 Translated code 
                 R-- 
                 RW- 
                 No 
                 — 
                 — 
                 — 
                 — 
                 --X 
                 RW- 
               
               
                 execution mode 
               
               
                 Native Execution mode 
                 R-X 
                 RW- 
                 No 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
               
               
                   
               
               
                 Notes: 
               
               
                 1. R,W, and X means Read, Write and Execute permissions, respectively. 
               
               
                 2. In x86 code and data, RWX permissions are only given when OS and VMM give such accesses 
               
             
          
         
       
     
     While some embodiments discussed herein provide “supervisor” and “non-supervisor” modes with different privileges for the binary translation code, the underlying principles of the invention are not limited to only two privilege levels. For example, the interpreter  824  of the binary translation code, if it is present, may operate in another separate mode with different privileges. Similarly, not all operating modes need to be present. For example, the full translation model may not have the native execution mode and the interpreter  824  may replace the function of the native execution mode. A partial translation model may not have the transition paths between the translated code execution and binary translation code “supervisor” mode. Though each hardware and software co-designed binary translation system instance may have variances in its configurations, the same principle can be applied to make the hardware/software co-designed processor more secure and less vulnerable to malicious attacks. 
     Embodiments of the invention may include various steps, which have been described above. The steps may be embodied in machine-executable instructions which may be used to cause a general-purpose or special-purpose processor to perform the steps. Alternatively, these steps may be performed by specific hardware components that contain hardwired logic for performing the steps, or by any combination of programmed computer components and custom hardware components. 
     As described herein, instructions may refer to specific configurations of hardware such as application specific integrated circuits (ASICs) configured to perform certain operations or having a predetermined functionality or software instructions stored in memory embodied in a non-transitory computer readable medium. Thus, the techniques shown in the figures can be implemented using code and data stored and executed on one or more electronic devices (e.g., an end station, a network element, etc.). Such electronic devices store and communicate (internally and/or with other electronic devices over a network) code and data using computer machine-readable media, such as non-transitory computer machine-readable storage media (e.g., magnetic disks; optical disks; random access memory; read only memory; flash memory devices; phase-change memory) and transitory computer machine-readable communication media (e.g., electrical, optical, acoustical or other form of propagated signals—such as carrier waves, infrared signals, digital signals, etc.). In addition, such electronic devices typically include a set of one or more processors coupled to one or more other components, such as one or more storage devices (non-transitory machine-readable storage media), user input/output devices (e.g., a keyboard, a touchscreen, and/or a display), and network connections. The coupling of the set of processors and other components is typically through one or more busses and bridges (also termed as bus controllers). The storage device and signals carrying the network traffic respectively represent one or more machine-readable storage media and machine-readable communication media. Thus, the storage device of a given electronic device typically stores code and/or data for execution on the set of one or more processors of that electronic device. Of course, one or more parts of an embodiment of the invention may be implemented using different combinations of software, firmware, and/or hardware. Throughout this detailed description, for the purposes of explanation, numerous specific details were set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without some of these specific details. In certain instances, well known structures and functions were not described in elaborate detail in order to avoid obscuring the subject matter of the present invention. Accordingly, the scope and spirit of the invention should be judged in terms of the claims which follow.