Statistical stack profiler for Windows x64

base/profiler/stack_sampling_profiler_win.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/profiler/stack_sampling_profiler.h"
+
+#include <dbghelp.h>
+#include <map>
+#include <utility>
+#include <windows.h>
+
+#include "base/logging.h"
+#include "base/time/time.h"
+#include "base/win/pe_image.h"
+#include "base/win/scoped_handle.h"
+
+namespace base {
+
+namespace {
+
+class NativeStackSamplerWin : public StackSamplingProfiler::NativeStackSampler {
+ public:
+  explicit NativeStackSamplerWin(win::ScopedHandle thread_handle);
+  ~NativeStackSamplerWin() override;
+
+  // StackSamplingProfiler::NativeStackSampler:
+  void ProfileRecordingStarting(
+      StackSamplingProfiler::Profile* profile) override;
+  void RecordStackSample(StackSamplingProfiler::Sample* sample) override;
+  void ProfileRecordingStopped() override;
+
+ private:
+  static bool GetModuleInfo(HMODULE module,
+                            StackSamplingProfiler::Module* module_info);
+
+  void CopyToSample(const void* const instruction_pointers[],
+                    const HMODULE modules[],
+                    int stack_depth,
+                    StackSamplingProfiler::Sample* sample,
+                    std::vector<StackSamplingProfiler::Module>* module_infos);
+
+  win::ScopedHandle thread_handle_;
+  // Weak. Points to the profile being recorded between
+  // ProfileRecordingStarting() and ProfileRecordingStopped().
+  StackSamplingProfiler::Profile* current_profile_;
+  // Maps a module to the module's index within current_profile_->modules.
+  std::map<HMODULE, int> profile_module_index_;
+
+  DISALLOW_COPY_AND_ASSIGN(NativeStackSamplerWin);
+};
+
+// Walk the stack represented by |context| from the current frame downwards,
+// recording the instruction pointers for each frame in |instruction_pointers|.
+int RecordStack(CONTEXT* context,
+                int max_stack_size,
+                const void* instruction_pointers[],
+                bool* last_frame_is_unknown_function) {
+#ifdef _WIN64
+  *last_frame_is_unknown_function = false;
+
+  IMAGEHLP_SYMBOL64 sym;
+  sym.SizeOfStruct = sizeof(sym);
+  sym.MaxNameLength = 0;
+
+  for (int i = 0; i < max_stack_size; ++i) {
+    // Try to look up unwind metadata for the current function.
+    ULONG64 image_base;
+    PRUNTIME_FUNCTION runtime_function =
+        RtlLookupFunctionEntry(context->Rip, &image_base, nullptr);
+
+    instruction_pointers[i] = reinterpret_cast<void*>(context->Rip);
+
+    if (runtime_function) {
+      KNONVOLATILE_CONTEXT_POINTERS nvcontext = {0};
+      void* handler_data;
+      ULONG64 establisher_frame;
+      RtlVirtualUnwind(0, image_base, context->Rip, runtime_function, context,
+          &handler_data, &establisher_frame, &nvcontext);
+    } else {
+      // If we don't have a RUNTIME_FUNCTION, then we've encountered
+      // a leaf function.  Adjust the stack appropriately.
+      context->Rip = *reinterpret_cast<PDWORD64>(context->Rsp);
+      context->Rsp += 8;
+      *last_frame_is_unknown_function = true;
+    }
+
+    if (!context->Rip)
+      return i;
+  }
+  return max_stack_size;
+#else
+  return 0;
+#endif
+}
+
+// Fills in |modules| corresponding to the pointers to code in |addresses|. The
+// modules are returned with reference counts incremented should be freed with
+// FreeModules.
+void FindModulesForAddresses(const void* const addresses[], HMODULE modules[],
+                             int stack_depth,
+                             bool last_frame_is_unknown_function) {
+  const int module_frames = last_frame_is_unknown_function ? stack_depth - 1 :
+      stack_depth;
+  for (int i = 0; i < module_frames; ++i) {
+    HMODULE module = NULL;
+    if (GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
+                          reinterpret_cast<LPCTSTR>(addresses[i]),
+                          &module)) {
+      // HMODULE is the base address of the module.
+      DCHECK_LT(reinterpret_cast<const void*>(module), addresses[i]);
+      modules[i] = module;
+    }
+  }
+}
+
+// Free the modules returned by FindModulesForAddresses.
+void FreeModules(int stack_depth, HMODULE modules[]) {
+  for (int i = 0; i < stack_depth; ++i) {
+    if (modules[i])
+      ::FreeLibrary(modules[i]);
+  }
+}
+
+// Suspends the thread with |thread_handle|, records the stack into
+// |instruction_pointers|, then resumes the thread. Returns the size of the
+// stack.
+int SuspendThreadAndRecordStack(HANDLE thread_handle, int max_stack_size,
+                                const void* instruction_pointers[],
+                                bool* last_frame_is_unknown_function) {
+  if (RtlVirtualUnwind == nullptr || RtlLookupFunctionEntry == nullptr)
+    return 0;
+
+  if (::SuspendThread(thread_handle) == -1) {
+    LOG(ERROR) << "SuspendThread failed: " << GetLastError();
+    return 0;
+  }
+
+  CONTEXT thread_context = {0};
+  thread_context.ContextFlags = CONTEXT_FULL;
+  if (!::GetThreadContext(thread_handle, &thread_context)) {
+    LOG(ERROR) << "GetThreadContext failed: " << GetLastError();
+  }
+
+  int stack_depth = RecordStack(&thread_context, max_stack_size,
+                                instruction_pointers,
+                                last_frame_is_unknown_function);
+
+  if (::ResumeThread(thread_handle) == -1)

[zturner, 2015/03/19 02:54:12]

One minor comment here.  This will cause the thread to get a priority boost.  If
you want to minimize the impact that the sampler has on the program's normal
behavior, you may want to consider using SetThreadPriorityBoost() before calling
this function to disable the priority boost, and then call it again after
ResumeThread() returns to restore the normal state.  Up to you to decide whether
this is important, mostly just mentioning it here since it's easy to overlook.

[Mike Wittman, 2015/03/19 20:27:17]

Thanks for the heads up. I don't think we want priority boost, particularly for
non-UI threads. Added a scoped disable.

+    LOG(ERROR) << "ResumeThread failed: " << GetLastError();
+
+  return stack_depth;
+}
+
+}  // namespace
+
+scoped_ptr<StackSamplingProfiler::NativeStackSampler>
+StackSamplingProfiler::NativeStackSampler::Create(PlatformThreadId thread_id) {
+#if _WIN64
+  // Get the thread's handle.
+  HANDLE thread_handle = ::OpenThread(
+      THREAD_GET_CONTEXT | THREAD_SUSPEND_RESUME | THREAD_QUERY_INFORMATION,
+      FALSE,
+      thread_id);
+  DCHECK(thread_handle) << "OpenThread failed";
+
+  return scoped_ptr<NativeStackSampler>(new NativeStackSamplerWin(
+      win::ScopedHandle(thread_handle)));
+#else
+  return scoped_ptr<NativeStackSampler>();
+#endif
+}
+
+NativeStackSamplerWin::NativeStackSamplerWin(win::ScopedHandle thread_handle)
+    : thread_handle_(thread_handle.Take()) {
+#ifdef _WIN64
+  if (RtlVirtualUnwind == nullptr && RtlLookupFunctionEntry == nullptr) {
+    const HMODULE nt_dll_handle = ::GetModuleHandle(L"ntdll.dll");
+    // This should always be non-null, but handle just in case.
+    if (nt_dll_handle) {
+      reinterpret_cast<void*&>(RtlVirtualUnwind) =
+          ::GetProcAddress(nt_dll_handle, "RtlVirtualUnwind");
+      reinterpret_cast<void*&>(RtlLookupFunctionEntry) =
+          ::GetProcAddress(nt_dll_handle, "RtlLookupFunctionEntry");
+    }
+  }
+#endif
+}
+
+NativeStackSamplerWin::~NativeStackSamplerWin() {
+}
+
+void NativeStackSamplerWin::ProfileRecordingStarting(
+    StackSamplingProfiler::Profile* profile) {
+  current_profile_ = profile;
+  profile_module_index_.clear();
+}
+
+void NativeStackSamplerWin::RecordStackSample(
+    StackSamplingProfiler::Sample* sample) {
+  DCHECK(current_profile_);
+
+  const int max_stack_size = 64;
+  const void* instruction_pointers[max_stack_size] = {0};
+  HMODULE modules[max_stack_size] = {0};
+
+  bool last_frame_is_unknown_function = false;
+  int stack_depth = SuspendThreadAndRecordStack(
+      thread_handle_.Get(), max_stack_size, instruction_pointers,
+      &last_frame_is_unknown_function);
+  FindModulesForAddresses(instruction_pointers, modules, stack_depth,
+                          last_frame_is_unknown_function);
+  CopyToSample(instruction_pointers, modules, stack_depth, sample,
+               &current_profile_->modules);
+  FreeModules(stack_depth, modules);
+}
+
+void NativeStackSamplerWin::ProfileRecordingStopped() {
+  current_profile_ = nullptr;
+}
+
+// static
+bool NativeStackSamplerWin::GetModuleInfo(
+    HMODULE module,
+    StackSamplingProfiler::Module* module_info) {
+  wchar_t module_name[MAX_PATH];
+  DWORD result_length =
+      GetModuleFileName(module, module_name, arraysize(module_name));
+  if (result_length == 0)
+    return false;
+
+  module_info->filename = base::FilePath(module_name);
+
+  module_info->base_address = reinterpret_cast<const void*>(module);
+
+  GUID guid;
+  DWORD age;
+  win::PEImage(module).GetDebugId(&guid, &age);
+  module_info->id.insert(module_info->id.end(),
+                         reinterpret_cast<char*>(&guid),
+                         reinterpret_cast<char*>(&guid + 1));
+  module_info->id.insert(module_info->id.end(),
+                         reinterpret_cast<char*>(&age),
+                         reinterpret_cast<char*>(&age + 1));
+
+  return true;
+}
+
+void NativeStackSamplerWin::CopyToSample(
+    const void* const instruction_pointers[],
+    const HMODULE modules[],
+    int stack_depth,
+    StackSamplingProfiler::Sample* sample,
+    std::vector<StackSamplingProfiler::Module>* module_infos) {
+  sample->clear();
+  sample->reserve(stack_depth);
+
+  for (int i = 0; i < stack_depth; ++i) {
+    sample->push_back(StackSamplingProfiler::Frame());
+    StackSamplingProfiler::Frame& frame = sample->back();
+
+    frame.instruction_pointer = instruction_pointers[i];
+
+    // Record an invalid module index if we don't have a valid module.
+    if (!modules[i]) {
+      frame.module_index = -1;
+      continue;
+    }
+
+    auto loc = profile_module_index_.find(modules[i]);
+    if (loc == profile_module_index_.end()) {
+      StackSamplingProfiler::Module module_info;
+      // Record an invalid module index if we have a module but can't find
+      // information on it.
+      if (!GetModuleInfo(modules[i], &module_info)) {
+        frame.module_index = -1;
+        continue;
+      }
+      module_infos->push_back(module_info);
+      loc = profile_module_index_.insert(std::make_pair(
+          modules[i], static_cast<int>(module_infos->size() - 1))).first;
+    }
+
+    frame.module_index = loc->second;
+  }
+}
+
+}  // namespace base