#!/usr/bin/env python
#
# Copyright 2013 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
from __future__ import print_function
import base64
import os
import sys
import re
from optparse import OptionParser
"""Extracts the list of resident symbols of a library loaded in a process.
This scripts combines the extended output of memdump for a given process
(obtained through memdump -x PID) and the symbol table of a .so loaded in that
process (obtained through nm -C lib-with-symbols.so), filtering out only those
symbols that, at the time of the snapshot, were resident in memory (that are,
the symbols which start address belongs to a mapped page of the .so which was
resident at the time of the snapshot).
The aim is to perform a "code coverage"-like profiling of a binary, intersecting
run-time information (list of resident pages) and debug symbols.
"""
_PAGE_SIZE = 4096
def _TestBit(word, bit):
assert(bit >= 0 and bit < 8)
return not not ((word >> bit) & 1)
def _HexAddr(addr):
return hex(addr)[2:].zfill(8)
def _GetResidentPagesSet(memdump_contents, lib_name, verbose):
"""Parses the memdump output and extracts the resident page set for lib_name.
Args:
memdump_contents: Array of strings (lines) of a memdump output.
lib_name: A string containing the name of the library.so to be matched.
verbose: Print a verbose header for each mapping matched.
Returns:
A set of resident pages (the key is the page index) for all the
mappings matching .*lib_name.
"""
resident_pages = set()
MAP_RX = re.compile(
r'^([0-9a-f]+)-([0-9a-f]+) ([\w-]+) ([0-9a-f]+) .* "(.*)" \[(.*)\]$')
for line in memdump_contents:
line = line.rstrip('\r\n')
if line.startswith('[ PID'):
continue
r = MAP_RX.match(line)
if not r:
sys.stderr.write('Skipping %s from %s\n' % (line, memdump_file))
continue
map_start = int(r.group(1), 16)
map_end = int(r.group(2), 16)
prot = r.group(3)
offset = int(r.group(4), 16)
assert(offset % _PAGE_SIZE == 0)
lib = r.group(5)
enc_bitmap = r.group(6)
if not lib.endswith(lib_name):
continue
bitmap = base64.b64decode(enc_bitmap)
map_pages_count = (map_end - map_start + 1) / _PAGE_SIZE
bitmap_pages_count = len(bitmap) * 8
if verbose:
print('Found %s: mapped %d pages in mode %s @ offset %s.' %
(lib, map_pages_count, prot, _HexAddr(offset)))
print(' Map range in the process VA: [%s - %s]. Len: %s' %
(_HexAddr(map_start), _HexAddr(map_end),
_HexAddr(map_pages_count * _PAGE_SIZE)))
print(' Corresponding addresses in the binary: [%s - %s]. Len: %s' %
(_HexAddr(offset), _HexAddr(offset + map_end - map_start),
_HexAddr(map_pages_count * _PAGE_SIZE)))
print(' Bitmap: %d pages' % bitmap_pages_count)
print('')
assert(bitmap_pages_count >= map_pages_count)
for i in xrange(map_pages_count):
bitmap_idx = i / 8
bitmap_off = i % 8
if (bitmap_idx < len(bitmap) and
_TestBit(ord(bitmap[bitmap_idx]), bitmap_off)):
resident_pages.add(offset / _PAGE_SIZE + i)
return resident_pages
def main(argv):
NM_RX = re.compile(r'^([0-9a-f]+)\s+.*$')
parser = OptionParser()
parser.add_option("-r", "--reverse",
action="store_true", dest="reverse", default=False,
help="Print out non present symbols")
parser.add_option("-v", "--verbose",
action="store_true", dest="verbose", default=False,
help="Print out verbose debug information.")
(options, args) = parser.parse_args()
if len(args) != 3:
print('Usage: %s [-v] memdump.file nm.file library.so' % (os.path.basename(
argv[0])))
return 1
memdump_file = args[0]
nm_file = args[1]
lib_name = args[2]
if memdump_file == '-':
memdump_contents = sys.stdin.readlines()
else:
memdump_contents = open(memdump_file, 'r').readlines()
resident_pages = _GetResidentPagesSet(memdump_contents,
lib_name,
options.verbose)
# Process the nm symbol table, filtering out the resident symbols.
nm_fh = open(nm_file, 'r')
for line in nm_fh:
line = line.rstrip('\r\n')
# Skip undefined symbols (lines with no address).
if line.startswith(' '):
continue
r = NM_RX.match(line)
if not r:
sys.stderr.write('Skipping %s from %s\n' % (line, nm_file))
continue
sym_addr = int(r.group(1), 16)
sym_page = sym_addr / _PAGE_SIZE
last_sym_matched = (sym_page in resident_pages)
if (sym_page in resident_pages) != options.reverse:
print(line)
return 0
if __name__ == '__main__':
sys.exit(main(sys.argv))
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