Merge "Revert "Move GCStress BacktraceHelper to libbacktrace""

3 files changed, 19 insertions, 81 deletions

diff --git a/runtime/Android.bp b/runtime/Android.bp
index 6ec626591a..8411982b30 100644
--- a/runtime/Android.bp
+++ b/runtime/Android.bp
@@ -31,7 +31,6 @@ libart_cc_defaults {
         "aot_class_linker.cc",
         "art_field.cc",
         "art_method.cc",
-        "backtrace_helper.cc",
         "barrier.cc",
         "base/mem_map_arena_pool.cc",
         "base/mutex.cc",
diff --git a/runtime/backtrace_helper.cc b/runtime/backtrace_helper.cc
deleted file mode 100644
index c2c0ceeaee..0000000000
--- a/runtime/backtrace_helper.cc
+++ /dev/null
@@ -1,76 +0,0 @@
-/*
- * Copyright (C) 2018 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "backtrace_helper.h"
-
-#if defined(__linux__)
-
-#include <backtrace/Backtrace.h>
-#include <backtrace/BacktraceMap.h>
-
-#include <unistd.h>
-#include <sys/types.h>
-
-#else
-
-// For UNUSED
-#include "base/macros.h"
-
-#endif
-
-namespace art {
-
-// We only really support libbacktrace on linux which is unfortunate but since this is only for
-// gcstress this isn't a huge deal.
-#if defined(__linux__)
-
-void BacktraceCollector::Collect() {
-  std::unique_ptr<BacktraceMap> map(BacktraceMap::Create(getpid()));
-  // We don't care about the function names. Turning this off makes everything significantly faster.
-  map->SetResolveNames(false);
-  std::unique_ptr<Backtrace> backtrace(Backtrace::Create(BACKTRACE_CURRENT_PROCESS,
-                                                         BACKTRACE_CURRENT_THREAD,
-                                                         map.get()));
-  backtrace->SetSkipFrames(true);
-  if (!backtrace->Unwind(skip_count_, nullptr)) {
-    return;
-  }
-  for (Backtrace::const_iterator it = backtrace->begin();
-       max_depth_ > num_frames_ && it != backtrace->end();
-       ++it) {
-    out_frames_[num_frames_++] = static_cast<uintptr_t>(it->pc);
-  }
-}
-
-#else
-
-#pragma clang diagnostic push
-#pragma clang diagnostic warning "-W#warnings"
-#warning "Backtrace collector is not implemented. GCStress cannot be used."
-#pragma clang diagnostic pop
-
-// We only have an implementation for linux. On other plaforms just return nothing. This is not
-// really correct but we only use this for hashing and gcstress so it's not too big a deal.
-void BacktraceCollector::Collect() {
-  UNUSED(skip_count_);
-  UNUSED(out_frames_);
-  UNUSED(max_depth_);
-  num_frames_ = 0;
-}
-
-#endif
-
-}  // namespace art
diff --git a/runtime/backtrace_helper.h b/runtime/backtrace_helper.h
index 8eda3fa0a1..ace118c50b 100644
--- a/runtime/backtrace_helper.h
+++ b/runtime/backtrace_helper.h
@@ -17,12 +17,11 @@
 #ifndef ART_RUNTIME_BACKTRACE_HELPER_H_
 #define ART_RUNTIME_BACKTRACE_HELPER_H_
 
-#include <stddef.h>
-#include <stdint.h>
+#include <unwind.h>
 
 namespace art {
 
-// Using libbacktrace
+// Based on debug malloc logic from libc/bionic/debug_stacktrace.cpp.
 class BacktraceCollector {
  public:
   BacktraceCollector(uintptr_t* out_frames, size_t max_depth, size_t skip_count)
@@ -33,9 +32,25 @@ class BacktraceCollector {
   }
 
   // Collect the backtrace, do not call more than once.
-  void Collect();
+  void Collect() {
+    _Unwind_Backtrace(&Callback, this);
+  }
 
  private:
+  static _Unwind_Reason_Code Callback(_Unwind_Context* context, void* arg) {
+    auto* const state = reinterpret_cast<BacktraceCollector*>(arg);
+    const uintptr_t ip = _Unwind_GetIP(context);
+    // The first stack frame is get_backtrace itself. Skip it.
+    if (ip != 0 && state->skip_count_ > 0) {
+      --state->skip_count_;
+      return _URC_NO_REASON;
+    }
+    // ip may be off for ARM but it shouldn't matter since we only use it for hashing.
+    state->out_frames_[state->num_frames_] = ip;
+    state->num_frames_++;
+    return state->num_frames_ >= state->max_depth_ ? _URC_END_OF_STACK : _URC_NO_REASON;
+  }
+
   uintptr_t* const out_frames_ = nullptr;
   size_t num_frames_ = 0u;
   const size_t max_depth_ = 0u;