libunwindstack: Add Memory::ReadTag() function for reading memory tags.

This uses an experimental Linux kernel API for reading the tags across
processes using ptrace.

Bug: 135772972

Test: Unit tests pass.
Change-Id: Ib1a09d9219166011de80cf250b756bb8a4bcdb0a

1 files changed, 99 insertions, 0 deletions

diff --git a/libunwindstack/tests/MemoryMteTest.cpp b/libunwindstack/tests/MemoryMteTest.cpp
new file mode 100644
index 0000000000..3ae322e351
--- /dev/null
+++ b/libunwindstack/tests/MemoryMteTest.cpp
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+
+#if defined(ANDROID_EXPERIMENTAL_MTE)
+
+#include <sys/mman.h>
+#include <sys/types.h>
+
+#include <gtest/gtest.h>
+
+#include <bionic/mte.h>
+
+#include "MemoryLocal.h"
+#include "MemoryRemote.h"
+#include "TestUtils.h"
+
+namespace unwindstack {
+
+static uintptr_t CreateTagMapping() {
+  uintptr_t mapping =
+      reinterpret_cast<uintptr_t>(mmap(nullptr, getpagesize(), PROT_READ | PROT_WRITE | PROT_MTE,
+                                       MAP_PRIVATE | MAP_ANONYMOUS, -1, 0));
+  if (reinterpret_cast<void*>(mapping) == MAP_FAILED) {
+    return 0;
+  }
+#if defined(__aarch64__)
+  __asm__ __volatile__(".arch_extension mte; stg %0, [%0]"
+                       :
+                       : "r"(mapping + (1ULL << 56))
+                       : "memory");
+#endif
+  return mapping;
+}
+
+TEST(MemoryMteTest, remote_read_tag) {
+#if !defined(__aarch64__)
+  GTEST_SKIP() << "Requires aarch64";
+#else
+  if (!mte_supported()) {
+    GTEST_SKIP() << "Requires MTE";
+  }
+#endif
+
+  uintptr_t mapping = CreateTagMapping();
+  ASSERT_NE(0U, mapping);
+
+  pid_t pid;
+  if ((pid = fork()) == 0) {
+    while (true)
+      ;
+    exit(1);
+  }
+  ASSERT_LT(0, pid);
+  TestScopedPidReaper reap(pid);
+
+  ASSERT_TRUE(TestAttach(pid));
+
+  MemoryRemote remote(pid);
+
+  EXPECT_EQ(1, remote.ReadTag(mapping));
+  EXPECT_EQ(0, remote.ReadTag(mapping + 16));
+
+  ASSERT_TRUE(TestDetach(pid));
+}
+
+TEST(MemoryMteTest, local_read_tag) {
+#if !defined(__aarch64__)
+  GTEST_SKIP() << "Requires aarch64";
+#else
+  if (!mte_supported()) {
+    GTEST_SKIP() << "Requires MTE";
+  }
+#endif
+
+  uintptr_t mapping = CreateTagMapping();
+  ASSERT_NE(0U, mapping);
+
+  MemoryLocal local;
+
+  EXPECT_EQ(1, local.ReadTag(mapping));
+  EXPECT_EQ(0, local.ReadTag(mapping + 16));
+}
+
+}  // namespace unwindstack
+
+#endif