Merge "Add a specialized LocalUnwinder object."

libunwindstack/Android.bp

@@ -62,6 +62,7 @@ cc_library {
         "MapInfo.cpp",
         "Maps.cpp",
         "Memory.cpp",
+        "LocalUnwinder.cpp",
         "Regs.cpp",
         "RegsArm.cpp",
         "RegsArm64.cpp",
@@ -125,6 +126,21 @@ cc_library {
 //-------------------------------------------------------------------------
 // Unit Tests
 //-------------------------------------------------------------------------
+cc_test_library {
+    name: "libunwindstack_local",
+    defaults: ["libunwindstack_flags"],
+    srcs: ["tests/TestLocal.cpp"],
+
+    cflags: [
+        "-O0",
+        "-g",
+    ],
+
+    shared_libs: [
+        "libunwindstack",
+    ],
+}
+
 cc_test {
     name: "libunwindstack_test",
     defaults: ["libunwindstack_flags"],
@@ -151,6 +167,7 @@ cc_test {
         "tests/ElfTest.cpp",
         "tests/ElfTestUtils.cpp",
         "tests/JitDebugTest.cpp",
+        "tests/LocalUnwinderTest.cpp",
         "tests/LogFake.cpp",
         "tests/MapInfoGetElfTest.cpp",
         "tests/MapInfoGetLoadBiasTest.cpp",

libunwindstack/LocalUnwinder.cpp

@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <pthread.h>
+#include <stdint.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <unwindstack/Elf.h>
+#include <unwindstack/LocalUnwinder.h>
+#include <unwindstack/MapInfo.h>
+#include <unwindstack/Maps.h>
+#include <unwindstack/Memory.h>
+#include <unwindstack/Regs.h>
+#include <unwindstack/RegsGetLocal.h>
+
+namespace unwindstack {
+
+bool LocalUnwinder::Init() {
+  pthread_rwlock_init(&maps_rwlock_, nullptr);
+
+  // Create the maps.
+  maps_.reset(new unwindstack::LocalUpdatableMaps());
+  if (!maps_->Parse()) {
+    maps_.reset();
+    return false;
+  }
+
+  process_memory_ = unwindstack::Memory::CreateProcessMemory(getpid());
+
+  return true;
+}
+
+bool LocalUnwinder::ShouldSkipLibrary(const std::string& map_name) {
+  for (const std::string& skip_library : skip_libraries_) {
+    if (skip_library == map_name) {
+      return true;
+    }
+  }
+  return false;
+}
+
+MapInfo* LocalUnwinder::GetMapInfo(uint64_t pc) {
+  pthread_rwlock_rdlock(&maps_rwlock_);
+  MapInfo* map_info = maps_->Find(pc);
+  pthread_rwlock_unlock(&maps_rwlock_);
+
+  if (map_info == nullptr) {
+    pthread_rwlock_wrlock(&maps_rwlock_);
+    // This is guaranteed not to invalidate any previous MapInfo objects so
+    // we don't need to worry about any MapInfo* values already in use.
+    if (maps_->Reparse()) {
+      map_info = maps_->Find(pc);
+    }
+    pthread_rwlock_unlock(&maps_rwlock_);
+  }
+
+  return map_info;
+}
+
+bool LocalUnwinder::Unwind(std::vector<LocalFrameData>* frame_info, size_t max_frames) {
+  std::unique_ptr<unwindstack::Regs> regs(unwindstack::Regs::CreateFromLocal());
+  unwindstack::RegsGetLocal(regs.get());
+
+  size_t num_frames = 0;
+  bool adjust_pc = false;
+  while (true) {
+    uint64_t cur_pc = regs->pc();
+    uint64_t cur_sp = regs->sp();
+
+    MapInfo* map_info = GetMapInfo(cur_pc);
+    if (map_info == nullptr) {
+      break;
+    }
+
+    Elf* elf = map_info->GetElf(process_memory_, true);
+    uint64_t rel_pc = elf->GetRelPc(cur_pc, map_info);
+    uint64_t step_pc = rel_pc;
+    uint64_t pc_adjustment;
+    if (adjust_pc) {
+      pc_adjustment = regs->GetPcAdjustment(rel_pc, elf);
+    } else {
+      pc_adjustment = 0;
+    }
+    step_pc -= pc_adjustment;
+    // Skip any locations that are within this library.
+    if (num_frames != 0 || !ShouldSkipLibrary(map_info->name)) {
+      // Add frame information.
+      std::string func_name;
+      uint64_t func_offset;
+      if (elf->GetFunctionName(rel_pc, &func_name, &func_offset)) {
+        frame_info->emplace_back(map_info, cur_pc - pc_adjustment, rel_pc - pc_adjustment,
+                                 func_name, func_offset);
+      } else {
+        frame_info->emplace_back(map_info, cur_pc - pc_adjustment, rel_pc - pc_adjustment, "", 0);
+      }
+      num_frames++;
+    }
+    if (!elf->valid()) {
+      break;
+    }
+    if (frame_info->size() == max_frames) {
+      break;
+    }
+
+    adjust_pc = true;
+    bool finished;
+    if (!elf->Step(rel_pc, step_pc, regs.get(), process_memory_.get(), &finished) || finished) {
+      break;
+    }
+    // pc and sp are the same, terminate the unwind.
+    if (cur_pc == regs->pc() && cur_sp == regs->sp()) {
+      break;
+    }
+  }
+  return num_frames != 0;
+}
+
+}  // namespace unwindstack

libunwindstack/Maps.cpp

@@ -105,4 +105,83 @@ const std::string RemoteMaps::GetMapsFile() const {
   return "/proc/" + std::to_string(pid_) + "/maps";
 }
 
+const std::string LocalUpdatableMaps::GetMapsFile() const {
+  return "/proc/self/maps";
+}
+
+bool LocalUpdatableMaps::Reparse() {
+  // New maps will be added at the end without deleting the old ones.
+  size_t last_map_idx = maps_.size();
+  if (!Parse()) {
+    // Delete any maps added by the Parse call.
+    for (size_t i = last_map_idx; i < maps_.size(); i++) {
+      delete maps_[i];
+    }
+    maps_.resize(last_map_idx);
+    return false;
+  }
+
+  size_t total_entries = maps_.size();
+  size_t search_map_idx = 0;
+  for (size_t new_map_idx = last_map_idx; new_map_idx < maps_.size(); new_map_idx++) {
+    MapInfo* new_map_info = maps_[new_map_idx];
+    uint64_t start = new_map_info->start;
+    uint64_t end = new_map_info->end;
+    uint64_t flags = new_map_info->flags;
+    std::string* name = &new_map_info->name;
+    for (size_t old_map_idx = search_map_idx; old_map_idx < last_map_idx; old_map_idx++) {
+      MapInfo* info = maps_[old_map_idx];
+      if (start == info->start && end == info->end && flags == info->flags && *name == info->name) {
+        // No need to check
+        search_map_idx = old_map_idx + 1;
+        delete new_map_info;
+        maps_[new_map_idx] = nullptr;
+        total_entries--;
+        break;
+      } else if (info->start > start) {
+        // Stop, there isn't going to be a match.
+        search_map_idx = old_map_idx;
+        break;
+      }
+
+      // Never delete these maps, they may be in use. The assumption is
+      // that there will only every be a handfull of these so waiting
+      // to destroy them is not too expensive.
+      saved_maps_.push_back(info);
+      maps_[old_map_idx] = nullptr;
+      total_entries--;
+    }
+    if (search_map_idx >= last_map_idx) {
+      break;
+    }
+  }
+
+  // Now move out any of the maps that never were found.
+  for (size_t i = search_map_idx; i < last_map_idx; i++) {
+    saved_maps_.push_back(maps_[i]);
+    maps_[i] = nullptr;
+    total_entries--;
+  }
+
+  // Sort all of the values such that the nullptrs wind up at the end, then
+  // resize them away.
+  std::sort(maps_.begin(), maps_.end(), [](const auto* a, const auto* b) {
+    if (a == nullptr) {
+      return false;
+    } else if (b == nullptr) {
+      return true;
+    }
+    return a->start < b->start;
+  });
+  maps_.resize(total_entries);
+
+  return true;
+}
+
+LocalUpdatableMaps::~LocalUpdatableMaps() {
+  for (auto map_info : saved_maps_) {
+    delete map_info;
+  }
+}
+
 }  // namespace unwindstack

libunwindstack/include/unwindstack/LocalUnwinder.h

@@ -0,0 +1,86 @@
+/*
+ * 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.
+ */
+
+#ifndef _LIBUNWINDSTACK_LOCAL_UNWINDER_H
+#define _LIBUNWINDSTACK_LOCAL_UNWINDER_H
+
+#include <pthread.h>
+#include <stdint.h>
+#include <sys/types.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <unwindstack/Error.h>
+#include <unwindstack/Maps.h>
+#include <unwindstack/Memory.h>
+
+namespace unwindstack {
+
+// Forward declarations.
+class Elf;
+struct MapInfo;
+
+struct LocalFrameData {
+  LocalFrameData(MapInfo* map_info, uint64_t pc, uint64_t rel_pc, const std::string& function_name,
+                 uint64_t function_offset)
+      : map_info(map_info),
+        pc(pc),
+        rel_pc(rel_pc),
+        function_name(function_name),
+        function_offset(function_offset) {}
+
+  MapInfo* map_info;
+  uint64_t pc;
+  uint64_t rel_pc;
+  std::string function_name;
+  uint64_t function_offset;
+};
+
+// This is a specialized class that should only be used for doing local unwinds.
+// The Unwind call can be made as multiple times on the same object, and it can
+// be called by multiple threads at the same time.
+// It is designed to be used in debugging circumstances to get a stack trace
+// as fast as possible.
+class LocalUnwinder {
+ public:
+  LocalUnwinder() = default;
+  LocalUnwinder(const std::vector<std::string>& skip_libraries) : skip_libraries_(skip_libraries) {}
+  ~LocalUnwinder() = default;
+
+  bool Init();
+
+  bool Unwind(std::vector<LocalFrameData>* frame_info, size_t max_frames);
+
+  bool ShouldSkipLibrary(const std::string& map_name);
+
+  MapInfo* GetMapInfo(uint64_t pc);
+
+  ErrorCode LastErrorCode() { return last_error_.code; }
+  uint64_t LastErrorAddress() { return last_error_.address; }
+
+ private:
+  pthread_rwlock_t maps_rwlock_;
+  std::unique_ptr<LocalUpdatableMaps> maps_ = nullptr;
+  std::shared_ptr<Memory> process_memory_;
+  std::vector<std::string> skip_libraries_;
+  ErrorData last_error_;
+};
+
+}  // namespace unwindstack
+
+#endif  // _LIBUNWINDSTACK_LOCAL_UNWINDER_H

libunwindstack/include/unwindstack/Maps.h

@@ -87,6 +87,19 @@ class LocalMaps : public RemoteMaps {
   virtual ~LocalMaps() = default;
 };
 
+class LocalUpdatableMaps : public Maps {
+ public:
+  LocalUpdatableMaps() : Maps() {}
+  virtual ~LocalUpdatableMaps();
+
+  bool Reparse();
+
+  const std::string GetMapsFile() const override;
+
+ private:
+  std::vector<MapInfo*> saved_maps_;
+};
+
 class BufferMaps : public Maps {
  public:
   BufferMaps(const char* buffer) : buffer_(buffer) {}

libunwindstack/tests/LocalUnwinderTest.cpp

@@ -0,0 +1,207 @@
+/*
+ * 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 <dlfcn.h>
+#include <inttypes.h>
+#include <signal.h>
+#include <stdint.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+#include <android-base/stringprintf.h>
+
+#include <unwindstack/LocalUnwinder.h>
+
+namespace unwindstack {
+
+static std::vector<LocalFrameData>* g_frame_info;
+static LocalUnwinder* g_unwinder;
+
+extern "C" void SignalLocalInnerFunction() {
+  g_unwinder->Unwind(g_frame_info, 256);
+}
+
+extern "C" void SignalLocalMiddleFunction() {
+  SignalLocalInnerFunction();
+}
+
+extern "C" void SignalLocalOuterFunction() {
+  SignalLocalMiddleFunction();
+}
+
+static void SignalLocalCallerHandler(int, siginfo_t*, void*) {
+  SignalLocalOuterFunction();
+}
+
+static std::string ErrorMsg(const std::vector<const char*>& function_names,
+                            const std::vector<LocalFrameData>& frame_info) {
+  std::string unwind;
+  size_t i = 0;
+  for (const auto& frame : frame_info) {
+    unwind += android::base::StringPrintf("#%02zu pc 0x%" PRIx64 " rel_pc 0x%" PRIx64, i++,
+                                          frame.pc, frame.rel_pc);
+    if (frame.map_info != nullptr) {
+      if (!frame.map_info->name.empty()) {
+        unwind += " " + frame.map_info->name;
+      } else {
+        unwind += android::base::StringPrintf(" 0x%" PRIx64 "-0x%" PRIx64, frame.map_info->start,
+                                              frame.map_info->end);
+      }
+      if (frame.map_info->offset != 0) {
+        unwind += android::base::StringPrintf(" offset 0x%" PRIx64, frame.map_info->offset);
+      }
+    }
+    if (!frame.function_name.empty()) {
+      unwind += " " + frame.function_name;
+      if (frame.function_offset != 0) {
+        unwind += android::base::StringPrintf("+%" PRId64, frame.function_offset);
+      }
+    }
+    unwind += '\n';
+  }
+
+  return std::string(
+             "Unwind completed without finding all frames\n"
+             "  Looking for function: ") +
+         function_names.front() + "\n" + "Unwind data:\n" + unwind;
+}
+
+// This test assumes that this code is compiled with optimizations turned
+// off. If this doesn't happen, then all of the calls will be optimized
+// away.
+extern "C" void LocalInnerFunction(LocalUnwinder* unwinder, bool unwind_through_signal) {
+  std::vector<LocalFrameData> frame_info;
+  g_frame_info = &frame_info;
+  g_unwinder = unwinder;
+  std::vector<const char*> expected_function_names;
+
+  if (unwind_through_signal) {
+    struct sigaction act, oldact;
+    memset(&act, 0, sizeof(act));
+    act.sa_sigaction = SignalLocalCallerHandler;
+    act.sa_flags = SA_RESTART | SA_ONSTACK;
+    ASSERT_EQ(0, sigaction(SIGUSR1, &act, &oldact));
+
+    raise(SIGUSR1);
+
+    ASSERT_EQ(0, sigaction(SIGUSR1, &oldact, nullptr));
+
+    expected_function_names = {"LocalOuterFunction",        "LocalMiddleFunction",
+                               "LocalInnerFunction",        "SignalLocalOuterFunction",
+                               "SignalLocalMiddleFunction", "SignalLocalInnerFunction"};
+  } else {
+    ASSERT_TRUE(unwinder->Unwind(&frame_info, 256));
+
+    expected_function_names = {"LocalOuterFunction", "LocalMiddleFunction", "LocalInnerFunction"};
+  }
+
+  for (auto& frame : frame_info) {
+    if (frame.function_name == expected_function_names.back()) {
+      expected_function_names.pop_back();
+      if (expected_function_names.empty()) {
+        break;
+      }
+    }
+  }
+
+  ASSERT_TRUE(expected_function_names.empty()) << ErrorMsg(expected_function_names, frame_info);
+}
+
+extern "C" void LocalMiddleFunction(LocalUnwinder* unwinder, bool unwind_through_signal) {
+  LocalInnerFunction(unwinder, unwind_through_signal);
+}
+
+extern "C" void LocalOuterFunction(LocalUnwinder* unwinder, bool unwind_through_signal) {
+  LocalMiddleFunction(unwinder, unwind_through_signal);
+}
+
+class LocalUnwinderTest : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    unwinder_.reset(new LocalUnwinder);
+    ASSERT_TRUE(unwinder_->Init());
+  }
+
+  std::unique_ptr<LocalUnwinder> unwinder_;
+};
+
+TEST_F(LocalUnwinderTest, local) {
+  LocalOuterFunction(unwinder_.get(), false);
+}
+
+TEST_F(LocalUnwinderTest, local_signal) {
+  LocalOuterFunction(unwinder_.get(), true);
+}
+
+TEST_F(LocalUnwinderTest, local_multiple) {
+  ASSERT_NO_FATAL_FAILURE(LocalOuterFunction(unwinder_.get(), false));
+
+  ASSERT_NO_FATAL_FAILURE(LocalOuterFunction(unwinder_.get(), true));
+
+  ASSERT_NO_FATAL_FAILURE(LocalOuterFunction(unwinder_.get(), false));
+
+  ASSERT_NO_FATAL_FAILURE(LocalOuterFunction(unwinder_.get(), true));
+}
+
+// This test verifies that doing an unwind before and after a dlopen
+// works. It's verifying that the maps read during the first unwind
+// do not cause a problem when doing the unwind using the code in
+// the dlopen'd code.
+TEST_F(LocalUnwinderTest, unwind_after_dlopen) {
+  // Prime the maps data.
+  ASSERT_NO_FATAL_FAILURE(LocalOuterFunction(unwinder_.get(), false));
+
+  std::string testlib(testing::internal::GetArgvs()[0]);
+  auto const value = testlib.find_last_of('/');
+  if (value == std::string::npos) {
+    testlib = "../";
+  } else {
+    testlib = testlib.substr(0, value + 1) + "../";
+  }
+  testlib += "libunwindstack_local.so";
+
+  void* handle = dlopen(testlib.c_str(), RTLD_NOW);
+  ASSERT_TRUE(handle != nullptr);
+
+  void (*unwind_function)(void*, void*) =
+      reinterpret_cast<void (*)(void*, void*)>(dlsym(handle, "TestlibLevel1"));
+  ASSERT_TRUE(unwind_function != nullptr);
+
+  std::vector<LocalFrameData> frame_info;
+  unwind_function(unwinder_.get(), &frame_info);
+
+  ASSERT_EQ(0, dlclose(handle));
+
+  std::vector<const char*> expected_function_names{"TestlibLevel1", "TestlibLevel2",
+                                                   "TestlibLevel3", "TestlibLevel4"};
+
+  for (auto& frame : frame_info) {
+    if (frame.function_name == expected_function_names.back()) {
+      expected_function_names.pop_back();
+      if (expected_function_names.empty()) {
+        break;
+      }
+    }
+  }
+
+  ASSERT_TRUE(expected_function_names.empty()) << ErrorMsg(expected_function_names, frame_info);
+}
+
+}  // namespace unwindstack

libunwindstack/tests/TestLocal.cpp

@@ -0,0 +1,39 @@
+/*
+ * 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 <unwindstack/LocalUnwinder.h>
+
+#include <vector>
+
+extern "C" void TestlibLevel4(void* unwinder_data, void* frame_data) {
+  unwindstack::LocalUnwinder* unwinder =
+      reinterpret_cast<unwindstack::LocalUnwinder*>(unwinder_data);
+  std::vector<unwindstack::LocalFrameData>* frame_info =
+      reinterpret_cast<std::vector<unwindstack::LocalFrameData>*>(frame_data);
+  unwinder->Unwind(frame_info, 256);
+}
+
+extern "C" void TestlibLevel3(void* unwinder_data, void* frame_data) {
+  TestlibLevel4(unwinder_data, frame_data);
+}
+
+extern "C" void TestlibLevel2(void* unwinder_data, void* frame_data) {
+  TestlibLevel3(unwinder_data, frame_data);
+}
+
+extern "C" void TestlibLevel1(void* unwinder_data, void* frame_data) {
+  TestlibLevel2(unwinder_data, frame_data);
+}

libunwindstack/tests/UnwindTest.cpp

@@ -106,15 +106,12 @@ static void VerifyUnwind(pid_t pid, Maps* maps, Regs* regs,
   Unwinder unwinder(512, maps, regs, process_memory);
   unwinder.Unwind();
 
-  std::string expected_function = expected_function_names.back();
-  expected_function_names.pop_back();
   for (auto& frame : unwinder.frames()) {
-    if (frame.function_name == expected_function) {
+    if (frame.function_name == expected_function_names.back()) {
+      expected_function_names.pop_back();
       if (expected_function_names.empty()) {
         break;
       }
-      expected_function = expected_function_names.back();
-      expected_function_names.pop_back();
     }
   }