Add test for an Android kernel bug about prctl.

Bug: 20017123

Change-Id: I8c109a06999a8bffcc8e8298b04ee637bb67d878
diff --git a/tests/Android.mk b/tests/Android.mk
index 8aba70b..4d9a136 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -93,6 +93,7 @@
     sys_epoll_test.cpp \
     sys_mman_test.cpp \
     sys_personality_test.cpp \
+    sys_prctl_test.cpp \
     sys_procfs_test.cpp \
     sys_resource_test.cpp \
     sys_select_test.cpp \
diff --git a/tests/sys_prctl_test.cpp b/tests/sys_prctl_test.cpp
new file mode 100644
index 0000000..5a563c1
--- /dev/null
+++ b/tests/sys_prctl_test.cpp
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2015 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 <gtest/gtest.h>
+
+#include <sys/mman.h>
+#include <sys/prctl.h>
+#include <unistd.h>
+#include "private/bionic_prctl.h"
+
+// http://b/20017123.
+TEST(sys_prctl, bug_20017123) {
+#if defined(__ANDROID__)
+  size_t page_size = static_cast<size_t>(sysconf(_SC_PAGESIZE));
+  void* p = mmap(NULL, page_size * 3, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  ASSERT_NE(MAP_FAILED, p);
+  ASSERT_EQ(0, mprotect(p, page_size, PROT_NONE));
+  ASSERT_NE(-1, prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, p, page_size * 3, "anonymous map space"));
+  volatile char* vp = reinterpret_cast<volatile char*>(p);
+  // Below memory access causes SEGV if the memory map is screwed up.
+  *(vp + page_size) = 0;
+  ASSERT_EQ(0, munmap(p, page_size * 3));
+#else
+  GTEST_LOG_(INFO) << "This test does nothing as it tests an Android specific kernel feature.";
+#endif
+}