[GWP-ASan] Mutex implementation [2].

Summary:
See D60593 for further information.
This patch pulls out the mutex implementation and the required definitions file.

We implement our own mutex for GWP-ASan currently, because:

1. We must be compatible with the sum of the most restrictive elements of the supporting allocator's build system. Current targets for GWP-ASan include Scudo (on Linux and Fuchsia), and bionic (on Android).
2. Scudo specifies `-nostdlib++ -nonodefaultlibs`, meaning we can't use `std::mutex` or `mtx_t`.
3. We can't use `sanitizer_common`'s mutex, as the supporting allocators cannot afford the extra maintenance (Android, Fuchsia) and code size (Fuchsia) overheads that this would incur.

In future, we would like to implement a shared base mutex for GWP-ASan, Scudo and sanitizer_common. This will likely happen when both GWP-ASan and Scudo standalone are not in the development phase, at which point they will have stable requirements.

Reviewers: vlad.tsyrklevich, morehouse, jfb

Reviewed By: morehouse

Subscribers: dexonsmith, srhines, cfe-commits, kubamracek, mgorny, cryptoad, jfb, #sanitizers, llvm-commits, vitalybuka, eugenis

Tags: #sanitizers, #llvm, #clang

Differential Revision: https://reviews.llvm.org/D61923

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@362138 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 239 insertions, 1 deletions

diff --git a/lib/gwp_asan/CMakeLists.txt b/lib/gwp_asan/CMakeLists.txt
index 1f6d973b3..6c83d86c6 100644
--- a/lib/gwp_asan/CMakeLists.txt
+++ b/lib/gwp_asan/CMakeLists.txt
@@ -3,17 +3,19 @@ add_compiler_rt_component(gwp_asan)
 include_directories(..)
 
 set(GWP_ASAN_SOURCES
+  platform_specific/mutex_posix.cpp
   random.cpp
 )
 
 set(GWP_ASAN_HEADERS
+  mutex.h
   random.h
 )
 
 # Ensure that GWP-ASan meets the delegated requirements of some supporting
 # allocators. Some supporting allocators (e.g. scudo standalone) cannot use any
 # parts of the C++ standard library.
-set(GWP_ASAN_CFLAGS -fno-rtti -fno-exceptions -nostdinc++)
+set(GWP_ASAN_CFLAGS -fno-rtti -fno-exceptions -nostdinc++ -pthread)
 
 # Remove -stdlib= which is unused when passing -nostdinc++.
 string(REGEX REPLACE "-stdlib=[a-zA-Z+]*" "" CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS})
@@ -37,3 +39,7 @@ if (COMPILER_RT_HAS_GWP_ASAN)
       ADDITIONAL_HEADERS ${GWP_ASAN_HEADERS}
       CFLAGS ${GWP_ASAN_CFLAGS})
 endif()
+
+if(COMPILER_RT_INCLUDE_TESTS)
+  add_subdirectory(tests)
+endif()
diff --git a/lib/gwp_asan/mutex.h b/lib/gwp_asan/mutex.h
new file mode 100644
index 000000000..c29df4cde
--- /dev/null
+++ b/lib/gwp_asan/mutex.h
@@ -0,0 +1,50 @@
+//===-- mutex.h -------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef GWP_ASAN_MUTEX_H_
+#define GWP_ASAN_MUTEX_H_
+
+#ifdef __unix__
+#include <pthread.h>
+#else
+#error "GWP-ASan is not supported on this platform."
+#endif
+
+namespace gwp_asan {
+class Mutex {
+public:
+  constexpr Mutex() = default;
+  ~Mutex() = default;
+  Mutex(const Mutex &) = delete;
+  Mutex &operator=(const Mutex &) = delete;
+  // Lock the mutex.
+  void lock();
+  // Nonblocking trylock of the mutex. Returns true if the lock was acquired.
+  bool tryLock();
+  // Unlock the mutex.
+  void unlock();
+
+private:
+#ifdef __unix__
+  pthread_mutex_t Mu = PTHREAD_MUTEX_INITIALIZER;
+#endif // defined(__unix__)
+};
+
+class ScopedLock {
+public:
+  explicit ScopedLock(Mutex &Mx) : Mu(Mx) { Mu.lock(); }
+  ~ScopedLock() { Mu.unlock(); }
+  ScopedLock(const ScopedLock &) = delete;
+  ScopedLock &operator=(const ScopedLock &) = delete;
+
+private:
+  Mutex &Mu;
+};
+} // namespace gwp_asan
+
+#endif // GWP_ASAN_MUTEX_H_
diff --git a/lib/gwp_asan/platform_specific/mutex_posix.cpp b/lib/gwp_asan/platform_specific/mutex_posix.cpp
new file mode 100644
index 000000000..e15bca882
--- /dev/null
+++ b/lib/gwp_asan/platform_specific/mutex_posix.cpp
@@ -0,0 +1,30 @@
+//===-- mutex_posix.cpp -----------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "mutex.h"
+
+#include <assert.h>
+#include <pthread.h>
+
+namespace gwp_asan {
+void Mutex::lock() {
+  int Status = pthread_mutex_lock(&Mu);
+  assert(Status == 0);
+  // Remove warning for non-debug builds.
+  (void)Status;
+}
+
+bool Mutex::tryLock() { return pthread_mutex_trylock(&Mu) == 0; }
+
+void Mutex::unlock() {
+  int Status = pthread_mutex_unlock(&Mu);
+  assert(Status == 0);
+  // Remove warning for non-debug builds.
+  (void)Status;
+}
+} // namespace gwp_asan
diff --git a/lib/gwp_asan/tests/CMakeLists.txt b/lib/gwp_asan/tests/CMakeLists.txt
new file mode 100644
index 000000000..6a59be5bc
--- /dev/null
+++ b/lib/gwp_asan/tests/CMakeLists.txt
@@ -0,0 +1,49 @@
+include(CompilerRTCompile)
+
+set(GWP_ASAN_UNITTEST_CFLAGS
+  ${COMPILER_RT_UNITTEST_CFLAGS}
+  ${COMPILER_RT_GTEST_CFLAGS}
+  -I${COMPILER_RT_SOURCE_DIR}/lib/
+  -O2)
+
+file(GLOB GWP_ASAN_HEADERS ../*.h)
+file(GLOB GWP_ASAN_UNITTESTS *.cpp)
+set(GWP_ASAN_UNIT_TEST_HEADERS
+  ${GWP_ASAN_HEADERS})
+
+add_custom_target(GwpAsanUnitTests)
+set_target_properties(GwpAsanUnitTests PROPERTIES FOLDER "Compiler-RT Tests")
+
+set(GWP_ASAN_UNITTEST_LINK_FLAGS ${COMPILER_RT_UNITTEST_LINK_FLAGS})
+list(APPEND GWP_ASAN_UNITTEST_LINK_FLAGS --driver-mode=g++)
+if(NOT WIN32)
+  list(APPEND GWP_ASAN_UNITTEST_LINK_FLAGS -lpthread)
+endif()
+
+if(COMPILER_RT_DEFAULT_TARGET_ARCH IN_LIST GWP_ASAN_SUPPORTED_ARCH)
+  # GWP-ASan unit tests are only run on the host machine.
+  set(arch ${COMPILER_RT_DEFAULT_TARGET_ARCH})
+
+  set(GWP_ASAN_TEST_RUNTIME RTGwpAsanTest.${arch})
+
+  set(GWP_ASAN_TEST_RUNTIME_OBJECTS
+    $<TARGET_OBJECTS:RTGwpAsan.${arch}>)
+
+  add_library(${GWP_ASAN_TEST_RUNTIME} STATIC
+    ${GWP_ASAN_TEST_RUNTIME_OBJECTS})
+
+  set_target_properties(${GWP_ASAN_TEST_RUNTIME} PROPERTIES
+    ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+    FOLDER "Compiler-RT Runtime tests")
+
+  set(GwpAsanTestObjects)
+  generate_compiler_rt_tests(GwpAsanTestObjects
+    GwpAsanUnitTests "GwpAsan-${arch}-Test" ${arch}
+    SOURCES ${GWP_ASAN_UNITTESTS} ${COMPILER_RT_GTEST_SOURCE}
+    RUNTIME ${GWP_ASAN_TEST_RUNTIME}
+    DEPS gtest ${GWP_ASAN_UNIT_TEST_HEADERS}
+    CFLAGS ${GWP_ASAN_UNITTEST_CFLAGS}
+    LINK_FLAGS ${GWP_ASAN_UNITTEST_LINK_FLAGS})
+  set_target_properties(GwpAsanUnitTests PROPERTIES
+    RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+endif()
diff --git a/lib/gwp_asan/tests/driver.cpp b/lib/gwp_asan/tests/driver.cpp
new file mode 100644
index 000000000..b402cec11
--- /dev/null
+++ b/lib/gwp_asan/tests/driver.cpp
@@ -0,0 +1,14 @@
+//===-- driver.cpp ----------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+
+int main(int argc, char **argv) {
+  testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}
diff --git a/lib/gwp_asan/tests/mutex_test.cpp b/lib/gwp_asan/tests/mutex_test.cpp
new file mode 100644
index 000000000..36f7e1d23
--- /dev/null
+++ b/lib/gwp_asan/tests/mutex_test.cpp
@@ -0,0 +1,89 @@
+//===-- mutex_test.cpp ------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "gwp_asan/mutex.h"
+#include "gtest/gtest.h"
+
+#include <atomic>
+#include <mutex>
+#include <thread>
+#include <vector>
+
+using gwp_asan::Mutex;
+using gwp_asan::ScopedLock;
+
+TEST(GwpAsanMutexTest, LockUnlockTest) {
+  Mutex Mu;
+
+  ASSERT_TRUE(Mu.tryLock());
+  ASSERT_FALSE(Mu.tryLock());
+  Mu.unlock();
+
+  Mu.lock();
+  Mu.unlock();
+
+  // Ensure that the mutex actually unlocked.
+  ASSERT_TRUE(Mu.tryLock());
+  Mu.unlock();
+}
+
+TEST(GwpAsanMutexTest, ScopedLockUnlockTest) {
+  Mutex Mu;
+  { ScopedLock L(Mu); }
+  // Locking will fail here if the scoped lock failed to unlock.
+  EXPECT_TRUE(Mu.tryLock());
+  Mu.unlock();
+
+  {
+    ScopedLock L(Mu);
+    EXPECT_FALSE(Mu.tryLock()); // Check that the c'tor did lock.
+
+    // Manually unlock and check that this succeeds.
+    Mu.unlock();
+    EXPECT_TRUE(Mu.tryLock()); // Manually lock.
+  }
+  EXPECT_TRUE(Mu.tryLock()); // Assert that the scoped destructor did unlock.
+  Mu.unlock();
+}
+
+static void synchronousIncrementTask(std::atomic<bool> *StartingGun, Mutex *Mu,
+                                     unsigned *Counter,
+                                     unsigned NumIterations) {
+  while (!StartingGun) {
+    // Wait for starting gun.
+  }
+  for (unsigned i = 0; i < NumIterations; ++i) {
+    ScopedLock L(*Mu);
+    (*Counter)++;
+  }
+}
+
+static void runSynchronisedTest(unsigned NumThreads, unsigned CounterMax) {
+  std::vector<std::thread> Threads;
+
+  ASSERT_TRUE(CounterMax % NumThreads == 0);
+
+  std::atomic<bool> StartingGun{false};
+  Mutex Mu;
+  unsigned Counter = 0;
+
+  for (unsigned i = 0; i < NumThreads; ++i)
+    Threads.emplace_back(synchronousIncrementTask, &StartingGun, &Mu, &Counter,
+                         CounterMax / NumThreads);
+
+  StartingGun = true;
+  for (auto &T : Threads)
+    T.join();
+
+  EXPECT_EQ(CounterMax, Counter);
+}
+
+TEST(GwpAsanMutexTest, SynchronisedCounterTest) {
+  runSynchronisedTest(4, 100000);
+  runSynchronisedTest(1000, 1000000);
+}