Update from https://crrev.com/333737

base/android/linker/linker_jni.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This is the Android-specific Chromium linker, a tiny shared library
 // implementing a custom dynamic linker that can be used to load the
 // real Chromium libraries (e.g. libcontentshell.so).
 
 // The main point of this linker is to be able to share the RELRO
 // section of libcontentshell.so (or equivalent) between the browser and
@@ skipping 429 matching lines @@
                               jlong load_address,
                               jobject lib_info_obj) {
   String zipfile_name_str(env, zipfile_name);
   String lib_name(env, library_name);
   ZipLibraryOpener opener(zipfile_name_str.c_str());
   return GenericLoadLibrary(
       env, lib_name.c_str(),
       static_cast<size_t>(load_address), lib_info_obj, opener);
 }
 
-// Enable the fallback due to lack of support for mapping the APK file with
-// executable permission in the crazy linker.
-//
-// |env| is the current JNI environment handle and is ignored here.
-// |clazz| is the static class handle for org.chromium.base.Linker,
-// and is ignored here.
-void EnableNoMapExecSupportFallback(JNIEnv* env, jclass clazz) {
-  crazy_context_t* context = GetCrazyContext();
-  crazy_context_set_no_map_exec_support_fallback_enabled(context, true);
-}
-
 // Class holding the Java class and method ID for the Java side Linker
 // postCallbackOnMainThread method.
 struct JavaCallbackBindings_class {
   jclass clazz;
   jmethodID method_id;
 
   // Initialize an instance.
   bool Init(JNIEnv* env, jclass linker_class) {
     clazz = reinterpret_cast<jclass>(env->NewGlobalRef(linker_class));
     return InitStaticMethodId(env,
@@ skipping 192 matching lines @@
   char buffer[kMaxFilePathLengthInZip + 1];
   if (crazy_library_file_path_in_zip_file(
           lib_name_c_str, buffer, sizeof(buffer)) == CRAZY_STATUS_FAILURE) {
     LOG_ERROR("%s: Failed to get full filename for library '%s'",
               __FUNCTION__, lib_name_c_str);
     buffer[0] = '\0';
   }
   return env->NewStringUTF(buffer);
 }
 
-// Check whether the device supports mapping the APK file with executable
-// permission.
-//
-// |env| is the current JNI environment handle.
-// |clazz| is the static class handle which is not used here.
-// |apkfile_name| is the filename of the APK.
-// Returns true if supported.
-jboolean CheckMapExecSupport(JNIEnv* env, jclass clazz, jstring apkfile_name) {
-  String apkfile_name_str(env, apkfile_name);
-  const char* apkfile_name_c_str = apkfile_name_str.c_str();
-
-  int fd = open(apkfile_name_c_str, O_RDONLY);
-  if (fd == -1) {
-    LOG_ERROR("%s: Failed to open %s\n", __FUNCTION__, apkfile_name_c_str);
-    return false;
-  }
-
-  LOG_INFO(
-      "%s: Memory mapping the first page of %s with executable permissions\n",
-      __FUNCTION__, apkfile_name_c_str);
-  void* address = mmap(NULL, PAGE_SIZE, PROT_EXEC, MAP_PRIVATE, fd, 0);
-
-  jboolean status;
-  if (address == MAP_FAILED) {
-    status = false;
-  } else {
-    status = true;
-    munmap(address, PAGE_SIZE);
-  }
-
-  close(fd);
-
-  LOG_INFO("%s: %s\n", __FUNCTION__, status ? "Supported" : "NOT supported");
-  return status;
-}
-
 // Check whether a library is page aligned and uncompressed in the APK file.
 //
 // |env| is the current JNI environment handle.
 // |clazz| is the static class handle which is not used here.
 // |apkfile_name| is the filename of the APK.
 // |library_name| is the library base name.
 // Returns true if page aligned and uncompressed.
 jboolean CheckLibraryIsMappableInApk(JNIEnv* env, jclass clazz,
                                      jstring apkfile_name,
                                      jstring library_name) {
@@ skipping 22 matching lines @@
      reinterpret_cast<void*>(&LoadLibrary)},
     {"nativeLoadLibraryInZipFile",
      "("
      "Ljava/lang/String;"
      "Ljava/lang/String;"
      "J"
      "Lorg/chromium/base/library_loader/Linker$LibInfo;"
      ")"
      "Z",
      reinterpret_cast<void*>(&LoadLibraryInZipFile)},
-    {"nativeEnableNoMapExecSupportFallback",
-     "("
-     ")"
-     "V",
-     reinterpret_cast<void*>(&EnableNoMapExecSupportFallback)},
     {"nativeRunCallbackOnUiThread",
      "("
      "J"
      ")"
      "V",
      reinterpret_cast<void*>(&RunCallbackOnUiThread)},
     {"nativeCreateSharedRelro",
      "("
      "Ljava/lang/String;"
      "J"
@@ skipping 18 matching lines @@
      "J"
      ")"
      "J",
      reinterpret_cast<void*>(&GetRandomBaseLoadAddress)},
     {"nativeGetLibraryFilePathInZipFile",
      "("
      "Ljava/lang/String;"
      ")"
      "Ljava/lang/String;",
      reinterpret_cast<void*>(&GetLibraryFilePathInZipFile)},
-    {"nativeCheckMapExecSupport",
-     "("
-     "Ljava/lang/String;"
-     ")"
-     "Z",
-     reinterpret_cast<void*>(&CheckMapExecSupport)},
     {"nativeCheckLibraryIsMappableInApk",
      "("
      "Ljava/lang/String;"
      "Ljava/lang/String;"
      ")"
      "Z",
      reinterpret_cast<void*>(&CheckLibraryIsMappableInApk)}, };
 
 }  // namespace
 
@@ skipping 42 matching lines @@
   crazy_context_t* context = GetCrazyContext();
   crazy_context_set_java_vm(context, vm, JNI_VERSION_1_4);
 
   // Register the function that the crazy linker can call to post code
   // for later execution.
   crazy_context_set_callback_poster(context, &PostForLaterExecution, NULL);
 
   LOG_INFO("%s: Done", __FUNCTION__);
   return JNI_VERSION_1_4;
 }