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Instrumentation of Linux Programs with Pin

Instrumentation of Linux Programs with Pin. http://rogue.colorado.edu/Pin. Robert Cohn & C-K Luk Platform Technology & Architecture Development Enterprise Platform Group Intel Corporation. People. Kim Hazelwood Cettei Robert Cohn Artur Klauser Geoff Lowney CK Luk Robert Muth

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Instrumentation of Linux Programs with Pin

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  1. Instrumentation of Linux Programs with Pin http://rogue.colorado.edu/Pin Robert Cohn & C-K Luk Platform Technology & Architecture Development Enterprise Platform Group Intel Corporation

  2. People Kim Hazelwood Cettei Robert Cohn Artur Klauser Geoff Lowney CK Luk Robert Muth Harish Patil Vijay Janapa Reddi Steven Wallace Pin Tutorial

  3. count[0]++; count[1]++; What is Instrumentation? Max = 0; for (p = head; p; p = p->next) { if (p->value > max) { max = p->value; } } printf(“In max\n”); User defined printf(“In Loop\n”); Pin Tutorial

  4. What can Instrumentation do? • Profiler for compiler optimization: • Basic-block count • Value profile • Micro architectural study: • Instrument branches to simulate branch predictors • Generate traces • Bug checking: • Find references to uninitialized, unallocated data • Software tools that use instrumentation: • Purify, Valgrind, Vtune Pin Tutorial

  5. Dynamic Instrumentation • Pin uses dynamic instrumentation • Instrument code when it is executed the first time • Many advantages over static instrumentation: • No need of a separate instrumentation pass • Can instrument all user-level codes executed • Shared libraries • Dynamically generated code • Easy to distinguish code and data • Instrumentation can be turned on/off • Can attach and instrument an already running process Pin Tutorial

  6. 1 1’ 2 3 2’ 4 5 7’ 6 Compiler 7 Execution-driven Instrumentation Original code Code cache Pin Tutorial

  7. 3’ 5’ 6’ Execution-driven Instrumentation Original code Code cache 1 1’ 2 3 2’ 4 5 7’ 6 Compiler 7 Pin Tutorial

  8. Transparent Instrumentation • Pin’s instrumentation is transparent: • Application itself sees the same: • Code addresses • Data addresses • Memory content • Instrumentation sees the original application: • Code addresses • Data address • Memory content CObserve original app. behavior, won’t expose latent bugs Pin Tutorial

  9. count(10) count(30) Instruction-level Instrumentation • Instrument relative to an instruction: • Before • After: • Fall-through edge • Taken edge (if it is a branch) cmp %esi, %edx jle <L1> mov $0x1, %edi count(20) <L1>: mov $0x8,%edi Pin Tutorial

  10. Pin Instrumentation APIs • Basic APIs are architecture independent: • Provide common functionalities such as finding out: • Control-flow changes • Memory accesses • Architecture-specific APIs for more detailed info • IA-32, EM64T, Itanium, Xscale • ATOM-based notion: • Instrumentation routines • Analysis routines Pin Tutorial

  11. Instrumentation Routines • User writes instrumentation routines: • Walk list of instructions, and • Insert calls to analysis routines • Pin invokes instrumentation routines when placing new instructions in code cache • Repeated execution uses already instrumented code in code cache Pin Tutorial

  12. Analysis Routines • User inserts calls to analysis routine: • User-specified arguments • E.g., increment counter, record data address, … • User writes in C, C++, ASM • Pin provides isolation so analysis does not affect application • Optimizations like inlining, register allocation, and scheduling make it efficient Pin Tutorial

  13. Example: Instruction Count $ /bin/ls Makefile atrace.o imageload.out itrace proccount Makefile.example imageload inscount0 itrace.o proccount.o atrace imageload.o inscount0.o itrace.out $ pin -t inscount0 -- /bin/ls Makefile atrace.o imageload.out itrace proccount Makefile.example imageload inscount0 itrace.o proccount.o atrace imageload.o inscount0.o itrace.out Count 422838 Pin Tutorial

  14. counter++; counter++; counter++; counter++; counter++; Example: Instruction Count sub $0xff, %edx cmp %esi, %edx jle <L1> mov $0x1, %edi add $0x10, %eax Pin Tutorial

  15. ManualExamples/inscount0.C #include <iostream> #include "pin.H" UINT64 icount = 0; VOID docount() { icount++; } VOID Instruction(INS ins, VOID *v) { INS_InsertCall(ins, IPOINT_BEFORE, (AFUNPTR)docount, IARG_END); } VOID Fini(INT32 code, VOID *v) { std::cerr << "Count " << icount << endl; } int main(int argc, char * argv[]) { PIN_Init(argc, argv); INS_AddInstrumentFunction(Instruction, 0); PIN_AddFiniFunction(Fini, 0); PIN_StartProgram(); return 0; } analysis routine instrumentation routine Pin Tutorial

  16. Example: Instruction Trace $ pin -t itrace -- /bin/ls Makefile atrace.o imageload.out itrace proccount Makefile.example imageload inscount0 itrace.o proccount.o atrace imageload.o inscount0.o itrace.out $ head itrace.out 0x40001e90 0x40001e91 0x40001ee4 0x40001ee5 0x40001ee7 0x40001ee8 0x40001ee9 0x40001eea 0x40001ef0 0x40001ee0 Pin Tutorial

  17. printip(ip); printip(ip); printip(ip); printip(ip); printip(ip); Example: Instruction Trace sub $0xff, %edx cmp %esi, %edx jle <L1> mov $0x1, %edi add $0x10, %eax Pin Tutorial

  18. ManualExamples/itrace.C #include <stdio.h> #include "pin.H" FILE * trace; VOID printip(VOID *ip) { fprintf(trace, "%p\n", ip); } VOID Instruction(INS ins, VOID *v) { INS_InsertCall(ins, IPOINT_BEFORE, (AFUNPTR)printip, IARG_INST_PTR, IARG_END); } int main(int argc, char * argv[]) { trace = fopen("itrace.out", "w"); PIN_Init(argc, argv); INS_AddInstrumentFunction(Instruction, 0); PIN_StartProgram(); return 0; } analysis routine argument Pin Tutorial

  19. Arguments to Analysis Routine Some examples: • IARG_UINT32 <value> • An integer value • IARG_REG_VALUE <register name> • Value of the register specified • IARG_INST_PTR • Instruction pointer (program counter) value • IARG_BRANCH_TAKEN • A non-zero value if the branch instrumented is taken • IARG_BRANCH_TARGET_ADDR • Target address of the branch instrumented • IARG_G_ARG0_CALLER • 1st general-purpose function argument, as seen by the caller • IARG_MEMORY_READ_EA • Effective address of a memory read • IARG_END • Must be the last in IARG list Pin Tutorial

  20. Instruction Inspection APIs Some examples: • INS_IsCall (INS ins) • True if ins is a call instruction • INS_IsRet (INS ins) • True if ins is a return instruction • INS_IsAtomicUpdate (INS ins) • True if ins is an instruction that may do atomic memory update • INS_IsMemoryRead (INS ins) • True if ins is a memory read instruction • INS_MemoryReadSize (INS ins) • Return the number of bytes read from memory by this inst • INS_Address (INS ins) • Return the instruction’s IP • INS_Size (INS ins) • Return the size of the instruction (in bytes) Pin Tutorial

  21. counter++; counter++; counter++; counter++; counter++; Example: Faster Instruction Count counter += 3 sub $0xff, %edx cmp %esi, %edx jle <L1> mov $0x1, %edi add $0x10, %eax counter += 2 Pin Tutorial

  22. ManualExamples/inscount1.C #include <stdio.h> #include "pin.H“ UINT64 icount = 0; VOID docount(INT32 c) { icount += c; } VOID Trace(TRACE trace, VOID *v) { for (BBL bbl = TRACE_BblHead(trace); BBL_Valid(bbl); bbl = BBL_Next(bbl)) { BBL_InsertCall(bbl, IPOINT_BEFORE, (AFUNPTR)docount, IARG_UINT32, BBL_NumIns(bbl), IARG_END); } } VOID Fini(INT32 code, VOID *v) { fprintf(stderr, "Count %lld\n", icount); } int main(int argc, char * argv[]) { PIN_Init(argc, argv); TRACE_AddInstrumentFunction(Trace, 0); PIN_AddFiniFunction(Fini, 0); PIN_StartProgram(); return 0; } Pin Tutorial

  23. Trace • Single-entry, multiple-exit instruction sequence • Create a new trace when a new entry is seen Program sub $0x5, %esi <L2>: add $0x3, %ebx cmp %esi, %ebx jnz <L2> … Trace 1 sub $0x5, %esi add $0x3, %ebx cmp %esi, %ebx jnz <L2> … Trace 2 add $0x3, %ebx cmp %esi, %ebx jnz <L2> … Pin Tutorial

  24. Instrumentation Granularity • “Just-in-time” instrumentation • Instrument when code is first executed • 2 granularities: • Instruction • Trace (basic blocks) • “Ahead-of-time” instrumentation • Instrument entire image when first loaded • 2 granularities: • Image (shared library, executable) • Routine Pin Tutorial

  25. Image Instrumentation Example: Reporting images loaded and unloaded $ pin -t imageload -- /bin/ls _insprofiler.C imageload imageload.out insprofiler.C proccount.C atrace.C imageload.C inscount0.C itrace.C staticcount.C atrace.o imageload.o inscount1.C makefile strace.C $ cat imageload.out Loading /bin/ls Loading /lib/ld-linux.so.2 Loading /lib/libtermcap.so.2 Loading /lib/i686/libc.so.6 Unloading /bin/ls Unloading /lib/ld-linux.so.2 Unloading /lib/libtermcap.so.2 Unloading /lib/i686/libc.so.6 Pin Tutorial

  26. #include <stdio.h> #include "pin.H" FILE * trace; VOID ImageLoad(IMG img, VOID *v) { fprintf(trace, "Loading %s\n", IMG_Name(img).c_str()); } VOID ImageUnload(IMG img, VOID *v) { fprintf(trace, "Unloading %s\n", IMG_Name(img).c_str()); } VOID Fini(INT32 code, VOID *v) { fclose(trace); } int main(int argc, char * argv[]) { trace = fopen("imageload.out", "w"); PIN_Init(argc, argv); IMG_AddInstrumentFunction(ImageLoad, 0); IMG_AddUnloadFunction(ImageUnload, 0); PIN_AddFiniFunction(Fini, 0); PIN_StartProgram(); return 0; } ManualExamples/imageload.C Pin Tutorial

  27. Routine Instrumentation SimpleExamples/malloctrace.C VOID Image(IMG img, VOID *v) { RTN mallocRtn = RTN_FindByName(img, "malloc"); if (RTN_Valid(mallocRtn)) { RTN_Open(mallocRtn); // fetch insts in mallocRtn RTN_InsertCall(mallocRtn, IPOINT_BEFORE, (AFUNPTR)Arg1Before, IARG_G_ARG0_CALLEE, IARG_END); RTN_InsertCall(mallocRtn, IPOINT_AFTER, (AFUNPTR)MallocAfter, IARG_G_RESULT0, IARG_END); RTN_Close(mallocRtn); } } before malloc’s entry 1st argument to malloc (#bytes wanted) before malloc’s return 1st return value (address allocated) Pin Tutorial

  28. Example Pintools • Instruction cache simulation • Replace itrace’sanalysis function • Data cache simulation • Like I-cache, but instrument loads/stores and pass effective address • Malloc/Free trace • instrument entry/exit points • Detect out-of-bound stack references • Instrument instructions that move stack pointer • Instrument loads/stores to check in bound Pin Tutorial

  29. Instrumentation Library • Pre-defined C++ classes • Implement common instrumentation tasks: • Icount • Instruction counting • Alarm • Trigger on an event (instruction count or IP) • Controller • Detect start and stop of an interval • Filter • Skip instrumentation in parts of the program (e.g., ignoring shared libraries) Pin Tutorial

  30. Instrumentation Performance Pin Tutorial CPin’s instrumentation is efficient

  31. Advanced Topics • Symbol and debug information • Hooks • Detach/Attach • Modifying program behavior • Debugging Pintools Pin Tutorial

  32. Symbol/Debug Information • Procedure names: • RTN_Name() • Shared library names: • IMG_Name() • File and line number information • PIN_FindLineFileByAddress() Pin Tutorial

  33. Hooks • Pintools can catch: • Shared library load/unload • IMG_AddInstrumentFunction() • IMG_AddUnloadFunction() • Program end • PIN_AddFiniFunction() • System calls • INS_IsSyscall() • Thread create/end • Pin 0 provides call backs for thread create and destroy • Yet to be done for Pin 2 Pin Tutorial

  34. Detach/Attach • Detach from Pin and execute original code • PIN_Detach() • Restore to full speed after sufficient profiling • Attach Pin to an already running process • Similar to debugger’s attach • Command line: “pin –pid 12345 –t inscount0” • Fast forward to where you want to start profiling Pin Tutorial

  35. Modify Program Behavior with Instrumentation • Analysis routines modify register values • IARG_RETURN_REGS<Reg> • Instrumentation modifies register operands • add %eax, %ebx => add %eax, %edx • Use virtual registers • add %eax, %ebx => add %eax, REG_INST_G0 • Modify memory • Pintool in the same address space as the program Pin Tutorial

  36. $ pin –pause_tool –t inscount0 -- /bin/ls Pausing to attach to pid 32017 Debugging Pintools • Invoke gdb with your pintool (but don’t use “run”) • On another window, start your pintool with “-pause_tool” • Go back to gdb: • Attach to the process • Use “cont” to continue execution; can set breakpoints as usual $ gdb inscount0 (gdb) (gdb) attach 32017 (gdb) break main (gdb) cont Pin Tutorial

  37. Status • Pin 0: Itanium-only release 10/2003 • Used by Intel, HP, Oracle, many universities • Pin 2: released 7/15/2004 • IA-32, EM64T, Xscale • Debian, Suse, Red Hat 7.2, 8.0, 9.0, EL3 • gcc, icc • Over 1000 downloads! Pin Tutorial

  38. Future Features • Instrumentation of multithreaded programs • Windows port? Pin Tutorial

  39. Summary • Pin: dynamic instrumentation framework for Linux • IA32, EM64T, Itanium, and Xscale • Easy to use, transparent, and efficient • Lots of sample tools • Write your own tool! http://rogue.colorado.edu/Pin Pin Tutorial

  40. Acknowledgments • Prof Dan Connors for providing the website at University of Colorado Pin Tutorial

  41. Project Engineering • Automatic nightly testing • 4 architectures • 6 Linux versions • 8 compilers • 9000 binaries • Automatically generated user manual, internal documentation using Doxygen Pin Tutorial

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