android_system_core/libunwindstack/tests/UnwindTest.cpp

/*
 * Copyright (C) 2017 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 <errno.h>
#include <signal.h>
#include <stdint.h>
#include <string.h>
#include <sys/ptrace.h>
#include <sys/syscall.h>
#include <unistd.h>

#include <gtest/gtest.h>

#include <atomic>
#include <memory>
#include <sstream>
#include <string>
#include <thread>
#include <vector>

#include <android-base/stringprintf.h>

#include <unwindstack/Maps.h>
#include <unwindstack/Memory.h>
#include <unwindstack/Regs.h>
#include <unwindstack/RegsGetLocal.h>
#include <unwindstack/Unwinder.h>

#include "TestUtils.h"

namespace unwindstack {

static std::atomic_bool g_ready;
static volatile bool g_ready_for_remote;
static volatile bool g_signal_ready_for_remote;
static std::atomic_bool g_finish;
static std::atomic_uintptr_t g_ucontext;

static void ResetGlobals() {
  g_ready = false;
  g_ready_for_remote = false;
  g_signal_ready_for_remote = false;
  g_finish = false;
  g_ucontext = 0;
}

static std::vector<const char*> kFunctionOrder{"OuterFunction", "MiddleFunction", "InnerFunction"};

static std::vector<const char*> kFunctionSignalOrder{"OuterFunction",        "MiddleFunction",
                                                     "InnerFunction",        "SignalOuterFunction",
                                                     "SignalMiddleFunction", "SignalInnerFunction"};

static void SignalHandler(int, siginfo_t*, void* sigcontext) {
  g_ucontext = reinterpret_cast<uintptr_t>(sigcontext);
  while (!g_finish.load()) {
  }
}

extern "C" void SignalInnerFunction() {
  g_signal_ready_for_remote = true;
  while (!g_finish.load()) {
  }
}

extern "C" void SignalMiddleFunction() {
  SignalInnerFunction();
}

extern "C" void SignalOuterFunction() {
  SignalMiddleFunction();
}

static void SignalCallerHandler(int, siginfo_t*, void*) {
  SignalOuterFunction();
}

static std::string ErrorMsg(const std::vector<const char*>& function_names, Unwinder& unwinder) {
  std::string unwind;
  for (size_t i = 0; i < unwinder.NumFrames(); i++) {
    unwind += unwinder.FormatFrame(i) + '\n';
  }

  return std::string(
             "Unwind completed without finding all frames\n"
             "  Looking for function: ") +
         function_names.front() + "\n" + "Unwind data:\n" + unwind;
}

static void VerifyUnwind(pid_t pid, Maps* maps, Regs* regs,
                         std::vector<const char*> expected_function_names) {
  auto process_memory(Memory::CreateProcessMemory(pid));

  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 (expected_function_names.empty()) {
        break;
      }
      expected_function = expected_function_names.back();
      expected_function_names.pop_back();
    }
  }

  ASSERT_TRUE(expected_function_names.empty()) << ErrorMsg(expected_function_names, unwinder);
}

// 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 InnerFunction(bool local, bool trigger_invalid_call) {
  if (local) {
    LocalMaps maps;
    ASSERT_TRUE(maps.Parse());
    std::unique_ptr<Regs> regs(Regs::CreateFromLocal());
    RegsGetLocal(regs.get());

    VerifyUnwind(getpid(), &maps, regs.get(), kFunctionOrder);
  } else {
    g_ready_for_remote = true;
    g_ready = true;
    if (trigger_invalid_call) {
      void (*crash_func)() = nullptr;
      crash_func();
    }
    while (!g_finish.load()) {
    }
  }
}

extern "C" void MiddleFunction(bool local, bool trigger_invalid_call) {
  InnerFunction(local, trigger_invalid_call);
}

extern "C" void OuterFunction(bool local, bool trigger_invalid_call) {
  MiddleFunction(local, trigger_invalid_call);
}

class UnwindTest : public ::testing::Test {
 public:
  void SetUp() override { ResetGlobals(); }
};

TEST_F(UnwindTest, local) {
  OuterFunction(true, false);
}

void WaitForRemote(pid_t pid, uint64_t addr, bool leave_attached, bool* completed) {
  *completed = false;
  // Need to sleep before attempting first ptrace. Without this, on the
  // host it becomes impossible to attach and ptrace sets errno to EPERM.
  usleep(1000);
  for (size_t i = 0; i < 1000; i++) {
    if (ptrace(PTRACE_ATTACH, pid, 0, 0) == 0) {
      ASSERT_TRUE(TestQuiescePid(pid))
          << "Waiting for process to quiesce failed: " << strerror(errno);

      MemoryRemote memory(pid);
      // Read the remote value to see if we are ready.
      bool value;
      if (memory.Read(addr, &value, sizeof(value)) && value) {
        *completed = true;
      }
      if (!*completed || !leave_attached) {
        ASSERT_EQ(0, ptrace(PTRACE_DETACH, pid, 0, 0));
      }
      if (*completed) {
        break;
      }
    } else {
      ASSERT_EQ(ESRCH, errno) << "ptrace attach failed with unexpected error: " << strerror(errno);
    }
    usleep(5000);
  }
}

TEST_F(UnwindTest, remote) {
  pid_t pid;
  if ((pid = fork()) == 0) {
    OuterFunction(false, false);
    exit(0);
  }
  ASSERT_NE(-1, pid);
  TestScopedPidReaper reap(pid);

  bool completed;
  WaitForRemote(pid, reinterpret_cast<uint64_t>(&g_ready_for_remote), true, &completed);
  ASSERT_TRUE(completed) << "Timed out waiting for remote process to be ready.";

  RemoteMaps maps(pid);
  ASSERT_TRUE(maps.Parse());
  std::unique_ptr<Regs> regs(Regs::RemoteGet(pid));
  ASSERT_TRUE(regs.get() != nullptr);

  VerifyUnwind(pid, &maps, regs.get(), kFunctionOrder);

  ASSERT_EQ(0, ptrace(PTRACE_DETACH, pid, 0, 0))
      << "ptrace detach failed with unexpected error: " << strerror(errno);
}

TEST_F(UnwindTest, from_context) {
  std::atomic_int tid(0);
  std::thread thread([&]() {
    tid = syscall(__NR_gettid);
    OuterFunction(false, false);
  });

  struct sigaction act, oldact;
  memset(&act, 0, sizeof(act));
  act.sa_sigaction = SignalHandler;
  act.sa_flags = SA_RESTART | SA_SIGINFO | SA_ONSTACK;
  ASSERT_EQ(0, sigaction(SIGUSR1, &act, &oldact));
  // Wait for the tid to get set.
  for (size_t i = 0; i < 100; i++) {
    if (tid.load() != 0) {
      break;
    }
    usleep(1000);
  }
  ASSERT_NE(0, tid.load());
  // Portable tgkill method.
  ASSERT_EQ(0, syscall(__NR_tgkill, getpid(), tid.load(), SIGUSR1)) << "Error: " << strerror(errno);

  // Wait for context data.
  void* ucontext;
  for (size_t i = 0; i < 2000; i++) {
    ucontext = reinterpret_cast<void*>(g_ucontext.load());
    if (ucontext != nullptr) {
      break;
    }
    usleep(1000);
  }
  ASSERT_TRUE(ucontext != nullptr) << "Timed out waiting for thread to respond to signal.";

  LocalMaps maps;
  ASSERT_TRUE(maps.Parse());
  std::unique_ptr<Regs> regs(Regs::CreateFromUcontext(Regs::CurrentMachineType(), ucontext));

  VerifyUnwind(getpid(), &maps, regs.get(), kFunctionOrder);

  ASSERT_EQ(0, sigaction(SIGUSR1, &oldact, nullptr));

  g_finish = true;
  thread.join();
}

static void RemoteThroughSignal(int signal, unsigned int sa_flags) {
  pid_t pid;
  if ((pid = fork()) == 0) {
    struct sigaction act, oldact;
    memset(&act, 0, sizeof(act));
    act.sa_sigaction = SignalCallerHandler;
    act.sa_flags = SA_RESTART | SA_ONSTACK | sa_flags;
    ASSERT_EQ(0, sigaction(signal, &act, &oldact));

    OuterFunction(false, signal == SIGSEGV);
    exit(0);
  }
  ASSERT_NE(-1, pid);
  TestScopedPidReaper reap(pid);

  bool completed;
  if (signal != SIGSEGV) {
    WaitForRemote(pid, reinterpret_cast<uint64_t>(&g_ready_for_remote), false, &completed);
    ASSERT_TRUE(completed) << "Timed out waiting for remote process to be ready.";
    ASSERT_EQ(0, kill(pid, SIGUSR1));
  }
  WaitForRemote(pid, reinterpret_cast<uint64_t>(&g_signal_ready_for_remote), true, &completed);
  ASSERT_TRUE(completed) << "Timed out waiting for remote process to be in signal handler.";

  RemoteMaps maps(pid);
  ASSERT_TRUE(maps.Parse());
  std::unique_ptr<Regs> regs(Regs::RemoteGet(pid));
  ASSERT_TRUE(regs.get() != nullptr);

  VerifyUnwind(pid, &maps, regs.get(), kFunctionSignalOrder);

  ASSERT_EQ(0, ptrace(PTRACE_DETACH, pid, 0, 0))
      << "ptrace detach failed with unexpected error: " << strerror(errno);
}

TEST_F(UnwindTest, remote_through_signal) {
  RemoteThroughSignal(SIGUSR1, 0);
}

TEST_F(UnwindTest, remote_through_signal_sa_siginfo) {
  RemoteThroughSignal(SIGUSR1, SA_SIGINFO);
}

TEST_F(UnwindTest, remote_through_signal_with_invalid_func) {
  RemoteThroughSignal(SIGSEGV, 0);
}

TEST_F(UnwindTest, remote_through_signal_sa_siginfo_with_invalid_func) {
  RemoteThroughSignal(SIGSEGV, SA_SIGINFO);
}

// Verify that using the same map while unwinding multiple threads at the
// same time doesn't cause problems.
TEST_F(UnwindTest, multiple_threads_unwind_same_map) {
  static constexpr size_t kNumConcurrentThreads = 100;

  LocalMaps maps;
  ASSERT_TRUE(maps.Parse());
  auto process_memory(Memory::CreateProcessMemory(getpid()));

  std::vector<std::thread*> threads;

  std::atomic_bool wait;
  wait = true;
  size_t frames[kNumConcurrentThreads];
  for (size_t i = 0; i < kNumConcurrentThreads; i++) {
    std::thread* thread = new std::thread([i, &frames, &maps, &process_memory, &wait]() {
      while (wait)
        ;
      std::unique_ptr<Regs> regs(Regs::CreateFromLocal());
      RegsGetLocal(regs.get());

      Unwinder unwinder(512, &maps, regs.get(), process_memory);
      unwinder.Unwind();
      frames[i] = unwinder.NumFrames();
      ASSERT_LE(3U, frames[i]) << "Failed for thread " << i;
    });
    threads.push_back(thread);
  }
  wait = false;
  for (auto thread : threads) {
    thread->join();
    delete thread;
  }
}

}  // namespace unwindstack