[compiler-rt] r276117 - [compiler-rt] [XRay] Basic initialization and flag definition for XRay runtime

Kostya Serebryany via llvm-commits llvm-commits at lists.llvm.org
Wed Jul 20 10:21:27 PDT 2016


Bots are unhappy...

[ 88%] Building CXX object
lib/xray/CMakeFiles/clang_rt.xray-x86_64.dir/xray_flags.cc.o
/mnt/b/sanitizer-buildbot1/sanitizer-x86_64-linux/build/llvm/projects/compiler-rt/lib/xray/xray_init.cc:23:10:
fatal error: 'llvm/Support/ELF.h' file not found
#include "llvm/Support/ELF.h"
         ^


On Wed, Jul 20, 2016 at 7:14 AM, Dean Michael Berris via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: dberris
> Date: Wed Jul 20 09:14:50 2016
> New Revision: 276117
>
> URL: http://llvm.org/viewvc/llvm-project?rev=276117&view=rev
> Log:
> [compiler-rt] [XRay] Basic initialization and flag definition for XRay
> runtime
>
> Summary:
> This patch implements the initialisation and patching routines for the
> XRay runtime, along with the necessary trampolines for function entry/exit
> handling. For now we only define the basic hooks for allowing an
> implementation to define a handler that gets run on function entry/exit. We
> expose a minimal API for controlling the behaviour of the runtime
> (patching, cleanup, and setting the handler to invoke when instrumenting).
>
> Depends on D19904
>
> Reviewers: echristo, kcc, rnk
>
> Subscribers: rnk, mehdi_amini, llvm-commits
>
> Differential Revision: https://reviews.llvm.org/D21612
>
> Added:
>     compiler-rt/trunk/include/xray/
>     compiler-rt/trunk/include/xray/xray_interface.h
>     compiler-rt/trunk/lib/xray/
>     compiler-rt/trunk/lib/xray/CMakeLists.txt
>     compiler-rt/trunk/lib/xray/xray_flags.cc
>     compiler-rt/trunk/lib/xray/xray_flags.h
>     compiler-rt/trunk/lib/xray/xray_flags.inc
>     compiler-rt/trunk/lib/xray/xray_init.cc
>     compiler-rt/trunk/lib/xray/xray_interface.cc
>     compiler-rt/trunk/lib/xray/xray_interface_internal.h
>     compiler-rt/trunk/lib/xray/xray_trampoline_x86.S
> Modified:
>     compiler-rt/trunk/CMakeLists.txt
>     compiler-rt/trunk/cmake/config-ix.cmake
>     compiler-rt/trunk/include/CMakeLists.txt
>     compiler-rt/trunk/lib/CMakeLists.txt
>
> Modified: compiler-rt/trunk/CMakeLists.txt
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/CMakeLists.txt?rev=276117&r1=276116&r2=276117&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/CMakeLists.txt (original)
> +++ compiler-rt/trunk/CMakeLists.txt Wed Jul 20 09:14:50 2016
> @@ -37,6 +37,8 @@ option(COMPILER_RT_BUILD_BUILTINS "Build
>  mark_as_advanced(COMPILER_RT_BUILD_BUILTINS)
>  option(COMPILER_RT_BUILD_SANITIZERS "Build sanitizers" ON)
>  mark_as_advanced(COMPILER_RT_BUILD_SANITIZERS)
> +option(COMPILER_RT_BUILD_XRAY "Build xray" ON)
> +mark_as_advanced(COMPILER_RT_BUILD_XRAY)
>
>  if (COMPILER_RT_STANDALONE_BUILD)
>    if (NOT LLVM_CONFIG_PATH)
>
> Modified: compiler-rt/trunk/cmake/config-ix.cmake
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/cmake/config-ix.cmake?rev=276117&r1=276116&r2=276117&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/cmake/config-ix.cmake (original)
> +++ compiler-rt/trunk/cmake/config-ix.cmake Wed Jul 20 09:14:50 2016
> @@ -161,6 +161,7 @@ set(ALL_SAFESTACK_SUPPORTED_ARCH ${X86}
>  set(ALL_CFI_SUPPORTED_ARCH ${X86} ${X86_64} ${MIPS64})
>  set(ALL_ESAN_SUPPORTED_ARCH ${X86_64})
>  set(ALL_SCUDO_SUPPORTED_ARCH ${X86_64})
> +set(ALL_XRAY_SUPPORTED_ARCH ${X86_64})
>
>  if(APPLE)
>    include(CompilerRTDarwinUtils)
> @@ -350,6 +351,9 @@ if(APPLE)
>    list_intersect(SCUDO_SUPPORTED_ARCH
>      ALL_SCUDO_SUPPORTED_ARCH
>      SANITIZER_COMMON_SUPPORTED_ARCH)
> +  list_intersect(XRAY_SUPPORTED_ARCH
> +    ALL_XRAY_SUPPORTED_ARCH
> +    SANITIZER_COMMON_SUPPORTED_ARCH)
>  else()
>    # Architectures supported by compiler-rt libraries.
>    filter_available_targets(SANITIZER_COMMON_SUPPORTED_ARCH
> @@ -373,6 +377,7 @@ else()
>    filter_available_targets(ESAN_SUPPORTED_ARCH ${ALL_ESAN_SUPPORTED_ARCH})
>    filter_available_targets(SCUDO_SUPPORTED_ARCH
>      ${ALL_SCUDO_SUPPORTED_ARCH})
> +  filter_available_targets(XRAY_SUPPORTED_ARCH ${ALL_XRAY_SUPPORTED_ARCH})
>  endif()
>
>  if (MSVC)
>
> Modified: compiler-rt/trunk/include/CMakeLists.txt
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/include/CMakeLists.txt?rev=276117&r1=276116&r2=276117&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/include/CMakeLists.txt (original)
> +++ compiler-rt/trunk/include/CMakeLists.txt Wed Jul 20 09:14:50 2016
> @@ -10,11 +10,18 @@ set(SANITIZER_HEADERS
>    sanitizer/msan_interface.h
>    sanitizer/tsan_interface_atomic.h)
>
> +set(XRAY_HEADERS
> +  xray/xray_interface.h)
> +
> +set(COMPILER_RT_HEADERS
> +  ${SANITIZER_HEADERS}
> +       ${XRAY_HEADERS})
> +
>  set(output_dir ${COMPILER_RT_OUTPUT_DIR}/include)
>
>  # Copy compiler-rt headers to the build tree.
>  set(out_files)
> -foreach( f ${SANITIZER_HEADERS} )
> +foreach( f ${COMPILER_RT_HEADERS} )
>    set( src ${CMAKE_CURRENT_SOURCE_DIR}/${f} )
>    set( dst ${output_dir}/${f} )
>    add_custom_command(OUTPUT ${dst}
> @@ -32,3 +39,7 @@ set_target_properties(compiler-rt-header
>  install(FILES ${SANITIZER_HEADERS}
>    PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
>    DESTINATION ${COMPILER_RT_INSTALL_PATH}/include/sanitizer)
> +# Install xray headers.
> +install(FILES ${XRAY_HEADERS}
> +  PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
> +  DESTINATION ${COMPILER_RT_INSTALL_PATH}/include/xray)
>
> Added: compiler-rt/trunk/include/xray/xray_interface.h
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/include/xray/xray_interface.h?rev=276117&view=auto
>
> ==============================================================================
> --- compiler-rt/trunk/include/xray/xray_interface.h (added)
> +++ compiler-rt/trunk/include/xray/xray_interface.h Wed Jul 20 09:14:50
> 2016
> @@ -0,0 +1,66 @@
> +//===-- xray_interface.h ----------------------------------------*- C++
> -*-===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
>
> +//===----------------------------------------------------------------------===//
> +//
> +// This file is a part of XRay, a dynamic runtime instrumentation system.
> +//
> +// APIs for controlling XRay functionality explicitly.
>
> +//===----------------------------------------------------------------------===//
> +#ifndef XRAY_XRAY_INTERFACE_H
> +#define XRAY_XRAY_INTERFACE_H
> +
> +#include <cstdint>
> +
> +extern "C" {
> +
> +enum XRayEntryType { ENTRY = 0, EXIT = 1 };
> +
> +// Provide a function to invoke for when instrumentation points are hit.
> This is
> +// a user-visible control surface that overrides the default
> implementation. The
> +// function provided should take the following arguments:
> +//
> +//   - function id: an identifier that indicates the id of a function;
> this id
> +//                  is generated by xray; the mapping between the
> function id
> +//                  and the actual function pointer is available through
> +//                  __xray_table.
> +//   - entry type: identifies what kind of instrumentation point was
> encountered
> +//                 (function entry, function exit, etc.). See the enum
> +//                 XRayEntryType for more details.
> +//
> +// Returns 1 on success, 0 on error.
> +extern int __xray_set_handler(void (*entry)(int32_t, XRayEntryType));
> +
> +// This removes whatever the currently provided handler is. Returns 1 on
> +// success, 0 on error.
> +extern int __xray_remove_handler();
> +
> +enum XRayPatchingStatus {
> +  NOT_INITIALIZED = 0,
> +  NOTIFIED = 1,
> +  ONGOING = 2,
> +  FAILED = 3
> +};
> +
> +// This tells XRay to patch the instrumentation points. This is an
> asynchronous
> +// process, and returns the following status in specific cases:
> +//
> +//   - 0 : XRay is not initialized.
> +//   - 1 : We've done the notification.
> +//   - 2 : Patching / un-patching is on-going.
> +extern XRayPatchingStatus __xray_patch();
> +
> +// Reverses the effect of __xray_patch(). This is an asynchronous
> process, and
> +// returns the following status in specific cases.
> +//
> +//   - 0 : XRay is not initialized.
> +//   - 1 : We've done the notification.
> +//   - 2 : Patching / un-patching is on-going.
> +extern int __xray_unpatch();
> +}
> +
> +#endif
>
> Modified: compiler-rt/trunk/lib/CMakeLists.txt
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/CMakeLists.txt?rev=276117&r1=276116&r2=276117&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/lib/CMakeLists.txt (original)
> +++ compiler-rt/trunk/lib/CMakeLists.txt Wed Jul 20 09:14:50 2016
> @@ -57,3 +57,7 @@ if(COMPILER_RT_BUILD_SANITIZERS)
>      add_subdirectory(scudo)
>    endif()
>  endif()
> +
> +if(COMPILER_RT_BUILD_XRAY)
> +  add_subdirectory(xray)
> +endif()
>
> Added: compiler-rt/trunk/lib/xray/CMakeLists.txt
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/CMakeLists.txt?rev=276117&view=auto
>
> ==============================================================================
> --- compiler-rt/trunk/lib/xray/CMakeLists.txt (added)
> +++ compiler-rt/trunk/lib/xray/CMakeLists.txt Wed Jul 20 09:14:50 2016
> @@ -0,0 +1,47 @@
> +# Build for the XRay runtime support library.
> +
> +set(XRAY_SOURCES
> +  xray_init.cc
> +       xray_interface.cc
> +       xray_flags.cc
> +)
> +
> +set(x86_64_SOURCES
> +               xray_trampoline_x86.S
> +               ${XRAY_SOURCES})
> +
> +include_directories(..)
> +include_directories(../../include)
> +
> +set(XRAY_CFLAGS ${SANITIZER_COMMON_CFLAGS})
> +
> +set(XRAY_COMMON_DEFINITIONS XRAY_HAS_EXCEPTIONS=1)
> +
> +add_compiler_rt_object_libraries(RTXray
> +               ARCHS ${XRAY_SUPPORTED_ARCH}
> +               SOURCES ${XRAY_SOURCES} CFLAGS ${XRAY_CFLAGS}
> +               DEFS ${XRAY_COMMON_DEFINITIONS})
> +
> +add_custom_target(xray)
> +set(XRAY_COMMON_RUNTIME_OBJECT_LIBS
> +               RTSanitizerCommon
> +               RTSanitizerCommonLibc)
> +
> +foreach (arch ${XRAY_SUPPORTED_ARCH})
> +               if (CAN_TARGET_${arch})
> +                               add_compiler_rt_runtime(clang_rt.xray
> +                                               STATIC
> +                                               ARCHS ${arch}
> +                                               SOURCES ${${arch}_SOURCES}
> +                                               CFLAGS ${XRAY_CFLAGS}
> +                                               DEFS
> ${XRAY_COMMON_DEFINITIONS}
> +                                               OBJECT_LIBS
> ${XRAY_COMMON_RUNTIME_OBJECT_LIBS}
> +                                               PARENT_TARGET xray)
> +               endif ()
> +endforeach()
> +
> +add_dependencies(compiler-rt xray)
> +
> +# if(COMPILER_RT_INCLUDE_TESTS)
> +#   add_subdirectory(tests)
> +# endif()
>
> Added: compiler-rt/trunk/lib/xray/xray_flags.cc
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/xray_flags.cc?rev=276117&view=auto
>
> ==============================================================================
> --- compiler-rt/trunk/lib/xray/xray_flags.cc (added)
> +++ compiler-rt/trunk/lib/xray/xray_flags.cc Wed Jul 20 09:14:50 2016
> @@ -0,0 +1,61 @@
> +//===-- xray_flags.cc -------------------------------------------*- C++
> -*-===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
>
> +//===----------------------------------------------------------------------===//
> +//
> +// This file is a part of XRay, a dynamic runtime instrumentation system.
> +//
> +// XRay flag parsing logic.
>
> +//===----------------------------------------------------------------------===//
> +
> +#include "xray_flags.h"
> +#include "sanitizer_common/sanitizer_common.h"
> +#include "sanitizer_common/sanitizer_flag_parser.h"
> +#include "sanitizer_common/sanitizer_libc.h"
> +
> +using namespace __sanitizer;
> +
> +namespace __xray {
> +
> +Flags xray_flags_dont_use_directly; // use via flags().
> +
> +void Flags::SetDefaults() {
> +#define XRAY_FLAG(Type, Name, DefaultValue, Description) Name =
> DefaultValue;
> +#include "xray_flags.inc"
> +#undef XRAY_FLAG
> +}
> +
> +static void RegisterXRayFlags(FlagParser *P, Flags *F) {
> +#define XRAY_FLAG(Type, Name, DefaultValue, Description)
>      \
> +  RegisterFlag(P, #Name, Description, &F->Name);
> +#include "xray_flags.inc"
> +#undef XRAY_FLAG
> +}
> +
> +void InitializeFlags() {
> +  SetCommonFlagsDefaults();
> +  auto *F = flags();
> +  F->SetDefaults();
> +
> +  FlagParser XRayParser;
> +  RegisterXRayFlags(&XRayParser, F);
> +  RegisterCommonFlags(&XRayParser);
> +
> +  // Override from command line.
> +  XRayParser.ParseString(GetEnv("XRAY_OPTIONS"));
> +
> +  InitializeCommonFlags();
> +
> +  if (Verbosity())
> +    ReportUnrecognizedFlags();
> +
> +  if (common_flags()->help) {
> +    XRayParser.PrintFlagDescriptions();
> +  }
> +}
> +
> +} // namespace __xray
>
> Added: compiler-rt/trunk/lib/xray/xray_flags.h
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/xray_flags.h?rev=276117&view=auto
>
> ==============================================================================
> --- compiler-rt/trunk/lib/xray/xray_flags.h (added)
> +++ compiler-rt/trunk/lib/xray/xray_flags.h Wed Jul 20 09:14:50 2016
> @@ -0,0 +1,37 @@
> +//===-- xray_flags.h -------------------------------------------*- C++
> -*-===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
>
> +//===----------------------------------------------------------------------===//
> +//
> +// This file is a part of XRay, a dynamic runtime instruementation system.
> +//
> +// XRay runtime flags.
>
> +//===----------------------------------------------------------------------===//
> +
> +#ifndef XRAY_FLAGS_H
> +#define XRAY_FLAGS_H
> +
> +#include "sanitizer_common/sanitizer_flag_parser.h"
> +
> +namespace __xray {
> +
> +struct Flags {
> +#define XRAY_FLAG(Type, Name, DefaultValue, Description) Type Name;
> +#include "xray_flags.inc"
> +#undef XRAY_FLAG
> +
> +  void SetDefaults();
> +};
> +
> +extern Flags xray_flags_dont_use_directly;
> +inline Flags *flags() { return &xray_flags_dont_use_directly; }
> +
> +void InitializeFlags();
> +
> +} // namespace __xray
> +
> +#endif // XRAY_FLAGS_H
>
> Added: compiler-rt/trunk/lib/xray/xray_flags.inc
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/xray_flags.inc?rev=276117&view=auto
>
> ==============================================================================
> --- compiler-rt/trunk/lib/xray/xray_flags.inc (added)
> +++ compiler-rt/trunk/lib/xray/xray_flags.inc Wed Jul 20 09:14:50 2016
> @@ -0,0 +1,18 @@
> +//===-- xray_flags.inc ------------------------------------------*- C++
> -*-===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
>
> +//===----------------------------------------------------------------------===//
> +//
> +// XRay runtime flags.
> +//
>
> +//===----------------------------------------------------------------------===//
> +#ifndef XRAY_FLAG
> +#error "Define XRAY_FLAG prior to including this file!"
> +#endif
> +
> +XRAY_FLAG(bool, patch_premain, true,
> +          "Whether to patch instrumentation points before main.")
>
> Added: compiler-rt/trunk/lib/xray/xray_init.cc
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/xray_init.cc?rev=276117&view=auto
>
> ==============================================================================
> --- compiler-rt/trunk/lib/xray/xray_init.cc (added)
> +++ compiler-rt/trunk/lib/xray/xray_init.cc Wed Jul 20 09:14:50 2016
> @@ -0,0 +1,68 @@
> +//===-- xray_init.cc --------------------------------------------*- C++
> -*-===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
>
> +//===----------------------------------------------------------------------===//
> +//
> +// This file is a part of XRay, a dynamic runtime instrumentation system.
> +//
> +// XRay initialisation logic.
>
> +//===----------------------------------------------------------------------===//
> +
> +#include <atomic>
> +#include <fcntl.h>
> +#include <strings.h>
> +#include <unistd.h>
> +
> +#include "sanitizer_common/sanitizer_common.h"
> +#include "xray_flags.h"
> +#include "xray_interface_internal.h"
> +#include "llvm/Support/ELF.h"
> +
> +extern "C" {
> +extern void __xray_init();
> +extern const XRaySledEntry __start_xray_instr_map[] __attribute__((weak));
> +extern const XRaySledEntry __stop_xray_instr_map[] __attribute__((weak));
> +}
> +
> +using namespace __xray;
> +
> +// We initialize some global variables that pertain to specific sections
> of XRay
> +// data structures in the binary. We do this for the current process using
> +// /proc/curproc/map and make sure that we're able to get it. We signal
> failure
> +// via a global atomic boolean to indicate whether we've initialized
> properly.
> +//
> +std::atomic<bool> XRayInitialized{false};
> +
> +// This should always be updated before XRayInitialized is updated.
> +std::atomic<__xray::XRaySledMap> XRayInstrMap{};
> +
> +// __xray_init() will do the actual loading of the current process'
> memory map
> +// and then proceed to look for the .xray_instr_map section/segment.
> +void __xray_init() {
> +  InitializeFlags();
> +  if (__start_xray_instr_map == nullptr) {
> +    Report("XRay instrumentation map missing. Not initializing XRay.\n");
> +    return;
> +  }
> +
> +  // Now initialize the XRayInstrMap global struct with the address of the
> +  // entries, reinterpreted as an array of XRaySledEntry objects. We use
> the
> +  // virtual pointer we have from the section to provide us the correct
> +  // information.
> +  __xray::XRaySledMap SledMap{};
> +  SledMap.Sleds = __start_xray_instr_map;
> +  SledMap.Entries = __stop_xray_instr_map - __start_xray_instr_map;
> +  XRayInstrMap.store(SledMap, std::memory_order_release);
> +  XRayInitialized.store(true, std::memory_order_release);
> +
> +  // FIXME: Check the flag/environment before patching.
> +  if (flags()->patch_premain)
> +    __xray_patch();
> +}
> +
> +__attribute__((section(".preinit_array"),
> +               used)) void (*__local_xray_preinit)(void) = __xray_init;
>
> Added: compiler-rt/trunk/lib/xray/xray_interface.cc
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/xray_interface.cc?rev=276117&view=auto
>
> ==============================================================================
> --- compiler-rt/trunk/lib/xray/xray_interface.cc (added)
> +++ compiler-rt/trunk/lib/xray/xray_interface.cc Wed Jul 20 09:14:50 2016
> @@ -0,0 +1,179 @@
> +//===-- xray_interface.cpp --------------------------------------*- C++
> -*-===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
>
> +//===----------------------------------------------------------------------===//
> +//
> +// This file is a part of XRay, a dynamic runtime instrumentation system.
> +//
> +// Implementation of the API functions.
> +//
>
> +//===----------------------------------------------------------------------===//
> +
> +#include "xray_interface_internal.h"
> +#include <atomic>
> +#include <cstdint>
> +#include <cstdio>
> +#include <errno.h>
> +#include <limits>
> +#include <sys/mman.h>
> +
> +namespace __xray {
> +
> +// This is the function to call when we encounter the entry or exit sleds.
> +std::atomic<void (*)(int32_t, XRayEntryType)>
> XRayPatchedFunction{nullptr};
> +
> +} // namespace __xray
> +
> +extern "C" {
> +// The following functions have to be defined in assembler, on a
> per-platform
> +// basis. See xray_trampoline_*.s files for implementations.
> +extern void __xray_FunctionEntry();
> +extern void __xray_FunctionExit();
> +}
> +
> +extern std::atomic<bool> XRayInitialized;
> +extern std::atomic<__xray::XRaySledMap> XRayInstrMap;
> +
> +int __xray_set_handler(void (*entry)(int32_t, XRayEntryType)) {
> +  if (XRayInitialized.load(std::memory_order_acquire)) {
> +    __xray::XRayPatchedFunction.store(entry, std::memory_order_release);
> +    return 1;
> +  }
> +  return 0;
> +}
> +
> +std::atomic<bool> XRayPatching{false};
> +
> +XRayPatchingStatus __xray_patch() {
> +  // FIXME: Make this happen asynchronously. For now just do this
> sequentially.
> +  if (!XRayInitialized.load(std::memory_order_acquire))
> +    return XRayPatchingStatus::NOT_INITIALIZED; // Not initialized.
> +
> +  static bool NotPatching = false;
> +  if (!XRayPatching.compare_exchange_strong(NotPatching, true,
> +                                            std::memory_order_acq_rel,
> +                                            std::memory_order_acquire)) {
> +    return XRayPatchingStatus::ONGOING; // Already patching.
> +  }
> +
> +  // Step 1: Compute the function id, as a unique identifier per function
> in the
> +  // instrumentation map.
> +  __xray::XRaySledMap InstrMap =
> XRayInstrMap.load(std::memory_order_acquire);
> +  if (InstrMap.Entries == 0)
> +    return XRayPatchingStatus::NOT_INITIALIZED;
> +
> +  int32_t FuncId = 1;
> +  static constexpr uint8_t CallOpCode = 0xe8;
> +  static constexpr uint16_t MovR10Seq = 0xba41;
> +  static constexpr uint8_t JmpOpCode = 0xe9;
> +  uint64_t CurFun = 0;
> +  for (std::size_t I = 0; I < InstrMap.Entries; I++) {
> +    auto Sled = InstrMap.Sleds[I];
> +    auto F = Sled.Function;
> +    if (CurFun == 0)
> +      CurFun = F;
> +    if (F != CurFun) {
> +      ++FuncId;
> +      CurFun = F;
> +    }
> +
> +    // While we're here, we should patch the nop sled. To do that we
> mprotect
> +    // the page containing the function to be writeable.
> +    void *PageAlignedAddr =
> +        reinterpret_cast<void *>(Sled.Address & ~((2 << 16) - 1));
> +    std::size_t MProtectLen =
> +        (Sled.Address + 12) - reinterpret_cast<uint64_t>(PageAlignedAddr);
> +    if (mprotect(PageAlignedAddr, MProtectLen,
> +                 PROT_READ | PROT_WRITE | PROT_EXEC) == -1) {
> +      printf("Failed mprotect: %d\n", errno);
> +      return XRayPatchingStatus::FAILED;
> +    }
> +
> +    static constexpr int64_t
> MinOffset{std::numeric_limits<int32_t>::min()};
> +    static constexpr int64_t
> MaxOffset{std::numeric_limits<int32_t>::max()};
> +    if (Sled.Kind == XRayEntryType::ENTRY) {
> +      // Here we do the dance of replacing the following sled:
> +      //
> +      // xray_sled_n:
> +      //   jmp +9
> +      //   <9 byte nop>
> +      //
> +      // With the following:
> +      //
> +      //   mov r10d, <function id>
> +      //   call <relative 32bit offset to entry trampoline>
> +      //
> +      // We need to do this in the following order:
> +      //
> +      // 1. Put the function id first, 2 bytes from the start of the sled
> (just
> +      // after the 2-byte jmp instruction).
> +      // 2. Put the call opcode 6 bytes from the start of the sled.
> +      // 3. Put the relative offset 7 bytes from the start of the sled.
> +      // 4. Do an atomic write over the jmp instruction for the "mov r10d"
> +      // opcode and first operand.
> +      //
> +      // Prerequisite is to compute the relative offset to the
> +      // __xray_FunctionEntry function's address.
> +      int64_t TrampolineOffset =
> +          reinterpret_cast<int64_t>(__xray_FunctionEntry) -
> +          (static_cast<int64_t>(Sled.Address) + 11);
> +      if (TrampolineOffset < MinOffset || TrampolineOffset > MaxOffset) {
> +        // FIXME: Print out an error here.
> +        continue;
> +      }
> +      *reinterpret_cast<uint32_t *>(Sled.Address + 2) = FuncId;
> +      *reinterpret_cast<uint8_t *>(Sled.Address + 6) = CallOpCode;
> +      *reinterpret_cast<uint32_t *>(Sled.Address + 7) = TrampolineOffset;
> +      std::atomic_store_explicit(
> +          reinterpret_cast<std::atomic<uint16_t> *>(Sled.Address),
> MovR10Seq,
> +          std::memory_order_release);
> +    }
> +
> +    if (Sled.Kind == XRayEntryType::EXIT) {
> +      // Here we do the dance of replacing the following sled:
> +      //
> +      // xray_sled_n:
> +      //   ret
> +      //   <10 byte nop>
> +      //
> +      // With the following:
> +      //
> +      //   mov r10d, <function id>
> +      //   jmp <relative 32bit offset to exit trampoline>
> +      //
> +      // 1. Put the function id first, 2 bytes from the start of the sled
> (just
> +      // after the 1-byte ret instruction).
> +      // 2. Put the jmp opcode 6 bytes from the start of the sled.
> +      // 3. Put the relative offset 7 bytes from the start of the sled.
> +      // 4. Do an atomic write over the jmp instruction for the "mov r10d"
> +      // opcode and first operand.
> +      //
> +      // Prerequisite is to compute the relative offset fo the
> +      // __xray_FunctionExit function's address.
> +      int64_t TrampolineOffset =
> +          reinterpret_cast<int64_t>(__xray_FunctionExit) -
> +          (static_cast<int64_t>(Sled.Address) + 11);
> +      if (TrampolineOffset < MinOffset || TrampolineOffset > MaxOffset) {
> +        // FIXME: Print out an error here.
> +        continue;
> +      }
> +      *reinterpret_cast<uint32_t *>(Sled.Address + 2) = FuncId;
> +      *reinterpret_cast<uint8_t *>(Sled.Address + 6) = JmpOpCode;
> +      *reinterpret_cast<uint32_t *>(Sled.Address + 7) = TrampolineOffset;
> +      std::atomic_store_explicit(
> +          reinterpret_cast<std::atomic<uint16_t> *>(Sled.Address),
> MovR10Seq,
> +          std::memory_order_release);
> +    }
> +
> +    if (mprotect(PageAlignedAddr, MProtectLen, PROT_READ | PROT_EXEC) ==
> -1) {
> +      printf("Failed mprotect: %d\n", errno);
> +      return XRayPatchingStatus::FAILED;
> +    }
> +  }
> +  XRayPatching.store(false, std::memory_order_release);
> +  return XRayPatchingStatus::NOTIFIED;
> +}
>
> Added: compiler-rt/trunk/lib/xray/xray_interface_internal.h
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/xray_interface_internal.h?rev=276117&view=auto
>
> ==============================================================================
> --- compiler-rt/trunk/lib/xray/xray_interface_internal.h (added)
> +++ compiler-rt/trunk/lib/xray/xray_interface_internal.h Wed Jul 20
> 09:14:50 2016
> @@ -0,0 +1,40 @@
> +//===-- xray_interface_internal.h -------------------------------*- C++
> -*-===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
>
> +//===----------------------------------------------------------------------===//
> +//
> +// This file is a part of XRay, a dynamic runtime instrumentation system.
> +//
> +// Implementation of the API functions. See also
> include/xray/xray_interface.h.
> +//
>
> +//===----------------------------------------------------------------------===//
> +#ifndef XRAY_INTERFACE_INTERNAL_H
> +#define XRAY_INTERFACE_INTERNAL_H
> +
> +#include "xray/xray_interface.h"
> +#include <cstdint>
> +
> +extern "C" {
> +
> +struct XRaySledEntry {
> +  uint64_t Address;
> +  uint64_t Function;
> +  unsigned char Kind;
> +  unsigned char AlwaysInstrument;
> +  unsigned char Padding[14]; // Need 32 bytes
> +};
> +}
> +
> +namespace __xray {
> +
> +struct XRaySledMap {
> +  const XRaySledEntry *Sleds;
> +  std::size_t Entries;
> +};
> +}
> +
> +#endif
>
> Added: compiler-rt/trunk/lib/xray/xray_trampoline_x86.S
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/xray_trampoline_x86.S?rev=276117&view=auto
>
> ==============================================================================
> --- compiler-rt/trunk/lib/xray/xray_trampoline_x86.S (added)
> +++ compiler-rt/trunk/lib/xray/xray_trampoline_x86.S Wed Jul 20 09:14:50
> 2016
> @@ -0,0 +1,93 @@
> +//===-- xray_trampoline_x86.s -----------------------------------*- ASM
> -*-===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
>
> +//===----------------------------------------------------------------------===//
> +//
> +// This file is a part of XRay, a dynamic runtime instrumentation system.
> +//
> +// This implements the X86-specific assembler for the trampolines.
> +//
>
> +//===----------------------------------------------------------------------===//
> +
> +       .text
> +       .file "xray_trampoline_x86.S"
> +       .globl __xray_FunctionEntry
> +       .align 16, 0x90
> +       .type __xray_FunctionEntry, at function
> +
> +__xray_FunctionEntry:
> +  .cfi_startproc
> +  // Save caller provided registers before doing any actual work.
> +       pushq %rbp
> +       .cfi_def_cfa_offset 16
> +       subq $72, %rsp
> +       movq    %rdi, 64(%rsp)
> +       movq  %rax, 56(%rsp)
> +       movq  %rdx, 48(%rsp)
> +       movq    %rsi, 40(%rsp)
> +       movq    %rcx, 32(%rsp)
> +       movq    %r8, 24(%rsp)
> +       movq    %r9, 16(%rsp)
> +
> +       // de-mangled, that's __xray::XRayPatchedFunction, and we're doing
> an acquire
> +       // load (on x86 is a normal mov instruction).
> +       movq    _ZN6__xray19XRayPatchedFunctionE(%rip), %rax
> +       testq   %rax, %rax
> +       je      .Ltmp0
> +
> +       // assume that %r10d has the function id.
> +       movl    %r10d, %edi
> +       xor     %esi,%esi
> +       callq   *%rax
> +.Ltmp0:
> +  // restore the registers
> +       movq    64(%rsp), %rdi
> +       movq  56(%rsp), %rax
> +       movq  48(%rsp), %rdx
> +       movq    40(%rsp), %rsi
> +       movq    32(%rsp), %rcx
> +       movq    24(%rsp), %r8
> +       movq    16(%rsp), %r9
> +       addq    $72, %rsp
> +       popq    %rbp
> +       retq
> +.Ltmp1:
> +       .size __xray_FunctionEntry, .Ltmp1-__xray_FunctionEntry
> +       .cfi_endproc
> +
> +       .globl __xray_FunctionExit
> +       .align 16, 0x90
> +       .type __xray_FunctionExit, at function
> +__xray_FunctionExit:
> +       .cfi_startproc
> +       // Save the important registers first. Since we're assuming that
> this
> +       // function is only jumped into, we only preserve the registers for
> +       // returning.
> +       // FIXME: Figure out whether this is sufficient.
> +       pushq   %rbp
> +       .cfi_def_cfa_offset 16
> +       subq    $24, %rsp
> +       .cfi_def_cfa_offset 32
> +       movq    %rax, 16(%rsp)
> +       movq    %rdx, 8(%rsp)
> +       movq    _ZN6__xray19XRayPatchedFunctionE(%rip), %rax
> +       testq %rax,%rax
> +       je      .Ltmp2
> +
> +       movl    %r10d, %edi
> +       movl    $1, %esi
> +       callq   *%rax
> +.Ltmp2:
> +  // Restore the important registers.
> +       movq    16(%rsp), %rax
> +       movq    8(%rsp), %rdx
> +       addq    $24, %rsp
> +       popq    %rbp
> +       retq
> +.Ltmp3:
> +       .size __xray_FunctionExit, .Ltmp3-__xray_FunctionExit
> +       .cfi_endproc
>
>
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> llvm-commits at lists.llvm.org
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