Android: Add chrome-specific dynamic linker.

build/android/pylib/linker/test_case.py

 # Copyright 2013 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.
 
 """Base class for linker-specific test cases.
 
    The custom dynamic linker can only be tested through a custom test case
    for various technical reasons:
 
      - It's an 'invisible feature', i.e. it doesn't expose a new API or
@@ skipping 34 matching lines @@
 from pylib import android_commands
 from pylib import flag_changer
 from pylib.base import base_test_result
 
 ResultType = base_test_result.ResultType
 
 _PACKAGE_NAME='org.chromium.content_linker_test_apk'
 _ACTIVITY_NAME='.ContentLinkerTestActivity'
 _COMMAND_LINE_FILE='/data/local/tmp/content-linker-test-command-line'
 
+# Set this to False if the implemetation doesn't always place Shared RELROs
+# in the browser process.
+_BROWSER_USES_SHARED_RELRO = True
+
 # Logcat filters used during each test. Only the 'chromium' one is really
 # needed, but the logs are added to the TestResult in case of error, and
 # it is handy to have the 'content_android_linker' ones as well when
 # troubleshooting.
 _LOGCAT_FILTERS = [ '*:s', 'chromium:v', 'content_android_linker:v' ]
 #_LOGCAT_FILTERS = [ '*:v' ]  ## DEBUG
 
 # Regular expression used to match status lines in logcat.
 re_status_line = re.compile(r'(BROWSER|RENDERER)_LINKER_TEST: (FAIL|SUCCESS)')
 
@@ skipping 329 matching lines @@
     memory_boundary = 0x40000000
     bad_libs = []
     for lib_name, lib_address in renderer_libs.iteritems():
       if lib_address >= memory_boundary:
         bad_libs.append((lib_name, lib_address))
 
     if bad_libs:
       logging.error('Renderer libraries loaded at high addresses: %s', bad_libs)
       return ResultType.FAIL, logs
 
-    if self.is_low_memory:
-      # For low-memory devices, the libraries must all be loaded at the same
-      # addresses. This also implicitly checks that the browser libraries are at
-      # low addresses.
+    if _BROWSER_USES_SHARED_RELRO or self.is_low_memory:
+      # The libraries must all be loaded at the same addresses. This also
+      # implicitly checks that the browser libraries are at low addresses.
       addr_mismatches = []
       for lib_name, lib_address in browser_libs.iteritems():
         lib_address2 = renderer_libs[lib_name]
         if lib_address != lib_address2:
           addr_mismatches.append((lib_name, lib_address, lib_address2))
 
       if addr_mismatches:
         logging.error('Library load address mismatches: %s',
             addr_mismatches)
         return ResultType.FAIL, logs
 
-    # For regular devices, check that libraries are loaded at 'high-addresses'.
+    # Otherwise, check that libraries are loaded at 'high-addresses'.
     # Note that for low-memory devices, the previous checks ensure that they
     # were loaded at low-addresses.
-    if not self.is_low_memory:
+    else:
       bad_libs = []
       for lib_name, lib_address in browser_libs.iteritems():
         if lib_address < memory_boundary:
           bad_libs.append((lib_name, lib_address))
 
       if bad_libs:
         logging.error('Browser libraries loaded at low addresses: %s', bad_libs)
         return ResultType.FAIL, logs
 
     # Everything's ok.
@@ skipping 34 matching lines @@
     # Check randomization in the browser libraries.
     logs = '\n'.join(logs_list)
 
     browser_status, browser_logs = _CheckLoadAddressRandomization(
         browser_lib_map_list, 'Browser')
 
     renderer_status, renderer_logs = _CheckLoadAddressRandomization(
         renderer_lib_map_list, 'Renderer')
 
     if not browser_status:
-      if self.is_low_memory:
+      if _BROWSER_USES_SHARED_RELRO or self.is_low_memory:
           return ResultType.FAIL, browser_logs
 
       # IMPORTANT NOTE: The system's ASLR implementation seems to be very poor
       # when starting an activity process in a loop with "adb shell am start".
       #
       # When simulating a regular device, loading libraries in the browser
       # process uses a simple mmap(NULL, ...) to let the kernel device where to
       # load the file (this is similar to what System.loadLibrary() does).
       #
       # Unfortunately, at least in the context of this test, doing so while
       # restarting the activity with the activity manager very, very, often
       # results in the system using the same load address for all 5 runs, or
       # sometimes only 4 out of 5.
       #
       # This has been tested experimentally on both Android 4.1.2 and 4.3.
       #
       # Note that this behaviour doesn't seem to happen when starting an
       # application 'normally', i.e. when using the application launcher to
       # start the activity.
       logging.info('Ignoring system\'s low randomization of browser libraries' +
                    ' for regular devices')
 
     if not renderer_status:
       return ResultType.FAIL, renderer_logs
 
     return ResultType.PASS, logs