4 files changed, 128 insertions, 0 deletions
diff --git a/base/android/library_loader/README.md b/base/android/library_loader/README.md
new file mode 100644
index 0000000000..7773b32b08
--- /dev/null
+++ b/base/android/library_loader/README.md
@@ -0,0 +1,10 @@
+# //base/android/library_loader
+
+Native code is split between this directory and:
+ * [//third_party/android_crazy_linker](../../../third_party/android_crazy_linker/README.chromium)
+
+Java code lives at:
+ * [//base/android/java/src/org/chromium/base/library_loader/](../java/src/org/chromium/base/library_loader/)
+
+A high-level guide to native code on Android exists at:
+ * [//docs/android_native_libraries.md](../../../docs/android_native_libraries.md)
diff --git a/base/android/library_loader/anchor_functions.cc b/base/android/library_loader/anchor_functions.cc
new file mode 100644
index 0000000000..0865d9d869
--- /dev/null
+++ b/base/android/library_loader/anchor_functions.cc
@@ -0,0 +1,79 @@
+// Copyright 2017 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.
+
+#include "base/android/library_loader/anchor_functions.h"
+
+#include "base/logging.h"
+#include "build/build_config.h"
+
+#if BUILDFLAG(SUPPORTS_CODE_ORDERING)
+
+// These functions are here to delimit the start and end of the ordered part of
+// .text. They require a suitably constructed orderfile, with these functions at
+// the beginning and end.
+//
+// These functions are weird: this is due to ICF (Identical Code Folding).
+// The linker merges functions that have the same code, which would be the case
+// if these functions were empty, or simple.
+// Gold's flag --icf=safe will *not* alias functions when their address is used
+// in code, but as of November 2017, we use the default setting that
+// deduplicates function in this case as well.
+//
+// Thus these functions are made to be unique, using inline .word in assembly.
+//
+// Note that code |CheckOrderingSanity()| below will make sure that these
+// functions are not aliased, in case the toolchain becomes really clever.
+extern "C" {
+
+// These functions have a well-defined ordering in this file, see the comment
+// in |IsOrderingSane()|.
+void dummy_function_end_of_ordered_text() {
+  asm(".word 0x21bad44d");
+  asm(".word 0xb815c5b0");
+}
+
+void dummy_function_start_of_ordered_text() {
+  asm(".word 0xe4a07375");
+  asm(".word 0x66dda6dc");
+}
+
+// These two symbols are defined by anchor_functions.lds and delimit the start
+// and end of .text.
+void linker_script_start_of_text();
+void linker_script_end_of_text();
+
+}  // extern "C"
+
+namespace base {
+namespace android {
+
+const size_t kStartOfText =
+    reinterpret_cast<size_t>(linker_script_start_of_text);
+const size_t kEndOfText = reinterpret_cast<size_t>(linker_script_end_of_text);
+const size_t kStartOfOrderedText =
+    reinterpret_cast<size_t>(dummy_function_start_of_ordered_text);
+const size_t kEndOfOrderedText =
+    reinterpret_cast<size_t>(dummy_function_end_of_ordered_text);
+
+bool IsOrderingSane() {
+  size_t here = reinterpret_cast<size_t>(&IsOrderingSane);
+  // The symbols linker_script_start_of_text and linker_script_end_of_text
+  // should cover all of .text, and dummy_function_start_of_ordered_text and
+  // dummy_function_end_of_ordered_text should cover the ordered part of it.
+  // This check is intended to catch the lack of ordering.
+  //
+  // Ordered text can start at the start of text, but should not cover the
+  // entire range. Most addresses are distinct nonetheless as the symbols are
+  // different, but linker-defined symbols have zero size and therefore the
+  // start address could be the same as the address of
+  // dummy_function_start_of_ordered_text.
+  return kStartOfText < here && here < kEndOfText &&
+         kStartOfOrderedText < kEndOfOrderedText &&
+         kStartOfText <= kStartOfOrderedText && kEndOfOrderedText < kEndOfText;
+}
+
+}  // namespace android
+}  // namespace base
+
+#endif  // BUILDFLAG(SUPPORTS_CODE_ORDERING)
diff --git a/base/android/library_loader/anchor_functions.h b/base/android/library_loader/anchor_functions.h
new file mode 100644
index 0000000000..9894583a52
--- /dev/null
+++ b/base/android/library_loader/anchor_functions.h
@@ -0,0 +1,32 @@
+// Copyright 2017 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.
+
+#ifndef BASE_ANDROID_LIBRARY_LOADER_ANCHOR_FUNCTIONS_H_
+#define BASE_ANDROID_LIBRARY_LOADER_ANCHOR_FUNCTIONS_H_
+
+#include <cstdint>
+#include "base/android/library_loader/anchor_functions_buildflags.h"
+
+#include "base/base_export.h"
+
+#if BUILDFLAG(SUPPORTS_CODE_ORDERING)
+
+namespace base {
+namespace android {
+
+// Start and end of .text, respectively.
+BASE_EXPORT extern const size_t kStartOfText;
+BASE_EXPORT extern const size_t kEndOfText;
+// Start and end of the ordered part of .text, respectively.
+BASE_EXPORT extern const size_t kStartOfOrderedText;
+BASE_EXPORT extern const size_t kEndOfOrderedText;
+
+// Returns true if the ordering looks sane.
+BASE_EXPORT bool IsOrderingSane();
+
+}  // namespace android
+}  // namespace base
+#endif  // BUILDFLAG(SUPPORTS_CODE_ORDERING)
+
+#endif  // BASE_ANDROID_LIBRARY_LOADER_ANCHOR_FUNCTIONS_H_
diff --git a/base/android/library_loader/anchor_functions.lds b/base/android/library_loader/anchor_functions.lds
new file mode 100644
index 0000000000..cdeaaa2a37
--- /dev/null
+++ b/base/android/library_loader/anchor_functions.lds
@@ -0,0 +1,7 @@
+# Copyright 2018 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.
+
+# Define symbols that point to the start and end of the .text section.
+PROVIDE_HIDDEN(linker_script_start_of_text = ADDR(.text));
+PROVIDE_HIDDEN(linker_script_end_of_text = ADDR(.text) + SIZEOF(.text));