libcutils: API to disable memory mitigations

Convenience API to disable memory mitigations, where we can specify
logging and also have a single place to update once a related bug is
fixed.

Bug: 166675194
Test: use API to disable memory mitigations
Change-Id: I4a3529ea1911925c49e31cc3809c2743e401c196

libcutils/Android.bp

@@ -158,6 +158,7 @@ cc_library {
         "canned_fs_config.cpp",
         "iosched_policy.cpp",
         "load_file.cpp",
+        "memory.cpp",
         "native_handle.cpp",
         "properties.cpp",
         "record_stream.cpp",
@@ -200,6 +201,9 @@ cc_library {
                 "uevent.cpp",
             ],
         },
+        bionic: {
+            header_libs: ["bionic_libc_platform_headers"],
+        },
 
         android_arm: {
             sanitize: {

libcutils/include/cutils/memory.h

@@ -28,6 +28,9 @@ extern "C" {
 size_t strlcpy(char *dst, const char *src, size_t size);
 #endif
 
+// Disables memory mitigations for the entire process, and logs appropriately.
+void process_disable_memory_mitigations();
+
 #ifdef __cplusplus
 } // extern "C"
 #endif

libcutils/memory.cpp

@@ -0,0 +1,39 @@
+/*
+ * 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.
+ */
+
+#include <cutils/memory.h>
+
+#include <log/log.h>
+
+#ifdef __BIONIC__
+#include <bionic/malloc.h>
+#endif
+
+void process_disable_memory_mitigations() {
+    bool success = false;
+#ifdef __BIONIC__
+    // TODO(b/158870657) is fixed and scudo is used globally, we can assert when an
+    // an error is returned.
+
+    success = android_mallopt(M_DISABLE_MEMORY_MITIGATIONS, nullptr, 0);
+#endif
+
+    if (success) {
+        ALOGI("Disabled memory mitigations for process.");
+    } else {
+        ALOGE("Could not disable memory mitigations for process.");
+    }
+}