Rewrite __cxa_atexit / __cxa_finalize

Simplify:
 - Use a single memory-mapped region to hold the table of destructors.
   Double its capacity each time it is expanded.
 - Add a recompaction pass at the end of __cxa_finalize that shifts
   entries forward and uses madvise to clean pages.

Bug: http://b/148055738
Test: bionic-unit-tests
Change-Id: Ieb9da2b88640a8a5277d217b43826b5b7e246781
(cherry picked from commit afa983c8d44400d45c1f0e2b8e90a8be04acf6f7)

2 files changed, 78 insertions, 0 deletions

diff --git a/tests/Android.bp b/tests/Android.bp
index 4bd96ad00..8b1eebc3f 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -79,6 +79,7 @@ cc_test_library {
     defaults: ["bionic_tests_defaults"],
     srcs: [
         "__aeabi_read_tp_test.cpp",
+        "__cxa_atexit_test.cpp",
         "alloca_test.cpp",
         "android_get_device_api_level.cpp",
         "arpa_inet_test.cpp",
diff --git a/tests/__cxa_atexit_test.cpp b/tests/__cxa_atexit_test.cpp
new file mode 100644
index 000000000..6a122d1cb
--- /dev/null
+++ b/tests/__cxa_atexit_test.cpp
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2020 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 <cxxabi.h>
+#include <gtest/gtest.h>
+
+TEST(__cxa_atexit, simple) {
+  int counter = 0;
+
+  __cxxabiv1::__cxa_atexit([](void* arg) { ++*static_cast<int*>(arg); }, &counter, &counter);
+
+  __cxxabiv1::__cxa_finalize(&counter);
+  ASSERT_EQ(counter, 1);
+
+  // The handler won't be called twice.
+  __cxxabiv1::__cxa_finalize(&counter);
+  ASSERT_EQ(counter, 1);
+}
+
+TEST(__cxa_atexit, order) {
+  static std::vector<int> actual;
+
+  char handles[2];
+
+  auto append_to_actual = [](void* arg) {
+    int* idx = static_cast<int*>(arg);
+    actual.push_back(*idx);
+    delete idx;
+  };
+
+  for (int i = 0; i < 500; ++i) {
+    __cxxabiv1::__cxa_atexit(append_to_actual, new int{i}, &handles[i % 2]);
+  }
+
+  __cxxabiv1::__cxa_finalize(&handles[0]);
+
+  for (int i = 500; i < 750; ++i) {
+    __cxxabiv1::__cxa_atexit(append_to_actual, new int{i}, &handles[1]);
+  }
+
+  __cxxabiv1::__cxa_finalize(&handles[1]);
+
+  std::vector<int> expected;
+  for (int i = 498; i >= 0; i -= 2) expected.push_back(i);
+  for (int i = 749; i >= 500; --i) expected.push_back(i);
+  for (int i = 499; i >= 1; i -= 2) expected.push_back(i);
+
+  ASSERT_EQ(expected.size(), actual.size());
+  for (size_t i = 0; i < expected.size(); ++i) {
+    ASSERT_EQ(expected[i], actual[i]) << "index=" << i;
+  }
+}