scripts/symbol.py

#!/usr/bin/python
#
# Copyright (C) 2013 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.

"""Module for looking up symbolic debugging information.

The information can include symbol names, offsets, and source locations.
"""

import glob
import os
import platform
import re
import subprocess
import unittest

ANDROID_BUILD_TOP = os.environ["ANDROID_BUILD_TOP"]
if not ANDROID_BUILD_TOP:
  ANDROID_BUILD_TOP = "."

def FindSymbolsDir():
  saveddir = os.getcwd()
  os.chdir(ANDROID_BUILD_TOP)
  try:
    cmd = ("CALLED_FROM_SETUP=true BUILD_SYSTEM=build/core "
           "SRC_TARGET_DIR=build/target make -f build/core/config.mk "
           "dumpvar-abs-TARGET_OUT_UNSTRIPPED")
    stream = subprocess.Popen(cmd, stdout=subprocess.PIPE, shell=True).stdout
    return os.path.join(ANDROID_BUILD_TOP, stream.read().strip())
  finally:
    os.chdir(saveddir)

SYMBOLS_DIR = FindSymbolsDir()

ARCH = "arm"


# These are private. Do not access them from other modules.
_CACHED_TOOLCHAIN = None
_CACHED_TOOLCHAIN_ARCH = None


def ToolPath(tool, toolchain=None):
  """Return a fully-qualified path to the specified tool"""
  if not toolchain:
    toolchain = FindToolchain()
  return glob.glob(os.path.join(toolchain, "*-" + tool))[0]


def FindToolchain():
  """Returns the toolchain matching ARCH."""
  global _CACHED_TOOLCHAIN, _CACHED_TOOLCHAIN_ARCH
  if _CACHED_TOOLCHAIN is not None and _CACHED_TOOLCHAIN_ARCH == ARCH:
    return _CACHED_TOOLCHAIN

  # We use slightly different names from GCC, and there's only one toolchain
  # for x86/x86_64. Note that these are the names of the top-level directory
  # rather than the _different_ names used lower down the directory hierarchy!
  gcc_dir = ARCH
  if gcc_dir == "arm64":
    gcc_dir = "aarch64"
  elif gcc_dir == "mips64":
    gcc_dir = "mips"
  elif gcc_dir == "x86_64":
    gcc_dir = "x86"

  os_name = platform.system().lower();

  available_toolchains = glob.glob("%s/prebuilts/gcc/%s-x86/%s/*-linux-*/bin/" % (ANDROID_BUILD_TOP, os_name, gcc_dir))
  if len(available_toolchains) == 0:
    raise Exception("Could not find tool chain for %s" % (ARCH))

  toolchain = sorted(available_toolchains)[-1]

  if not os.path.exists(ToolPath("addr2line", toolchain)):
    raise Exception("No addr2line for %s" % (toolchain))

  _CACHED_TOOLCHAIN = toolchain
  _CACHED_TOOLCHAIN_ARCH = ARCH
  print "Using %s toolchain from: %s" % (_CACHED_TOOLCHAIN_ARCH, _CACHED_TOOLCHAIN)
  return _CACHED_TOOLCHAIN


def SymbolInformation(lib, addr):
  """Look up symbol information about an address.

  Args:
    lib: library (or executable) pathname containing symbols
    addr: string hexidecimal address

  Returns:
    A list of the form [(source_symbol, source_location,
    object_symbol_with_offset)].

    If the function has been inlined then the list may contain
    more than one element with the symbols for the most deeply
    nested inlined location appearing first.  The list is
    always non-empty, even if no information is available.

    Usually you want to display the source_location and
    object_symbol_with_offset from the last element in the list.
  """
  info = SymbolInformationForSet(lib, set([addr]))
  return (info and info.get(addr)) or [(None, None, None)]


def SymbolInformationForSet(lib, unique_addrs):
  """Look up symbol information for a set of addresses from the given library.

  Args:
    lib: library (or executable) pathname containing symbols
    unique_addrs: set of hexidecimal addresses

  Returns:
    A dictionary of the form {addr: [(source_symbol, source_location,
    object_symbol_with_offset)]} where each address has a list of
    associated symbols and locations.  The list is always non-empty.

    If the function has been inlined then the list may contain
    more than one element with the symbols for the most deeply
    nested inlined location appearing first.  The list is
    always non-empty, even if no information is available.

    Usually you want to display the source_location and
    object_symbol_with_offset from the last element in the list.
  """
  if not lib:
    return None

  addr_to_line = CallAddr2LineForSet(lib, unique_addrs)
  if not addr_to_line:
    return None

  addr_to_objdump = CallObjdumpForSet(lib, unique_addrs)
  if not addr_to_objdump:
    return None

  result = {}
  for addr in unique_addrs:
    source_info = addr_to_line.get(addr)
    if not source_info:
      source_info = [(None, None)]
    if addr in addr_to_objdump:
      (object_symbol, object_offset) = addr_to_objdump.get(addr)
      object_symbol_with_offset = FormatSymbolWithOffset(object_symbol,
                                                         object_offset)
    else:
      object_symbol_with_offset = None
    result[addr] = [(source_symbol, source_location, object_symbol_with_offset)
        for (source_symbol, source_location) in source_info]

  return result


def CallAddr2LineForSet(lib, unique_addrs):
  """Look up line and symbol information for a set of addresses.

  Args:
    lib: library (or executable) pathname containing symbols
    unique_addrs: set of string hexidecimal addresses look up.

  Returns:
    A dictionary of the form {addr: [(symbol, file:line)]} where
    each address has a list of associated symbols and locations
    or an empty list if no symbol information was found.

    If the function has been inlined then the list may contain
    more than one element with the symbols for the most deeply
    nested inlined location appearing first.
  """
  if not lib:
    return None

  symbols = SYMBOLS_DIR + lib
  if not os.path.exists(symbols):
    return None

  cmd = [ToolPath("addr2line"), "--functions", "--inlines",
      "--demangle", "--exe=" + symbols]
  child = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE)

  result = {}
  addrs = sorted(unique_addrs)
  for addr in addrs:
    child.stdin.write("0x%s\n" % addr)
    child.stdin.flush()
    records = []
    first = True
    while True:
      symbol = child.stdout.readline().strip()
      if symbol == "??":
        symbol = None
      location = child.stdout.readline().strip()
      if location == "??:0":
        location = None
      if symbol is None and location is None:
        break
      records.append((symbol, location))
      if first:
        # Write a blank line as a sentinel so we know when to stop
        # reading inlines from the output.
        # The blank line will cause addr2line to emit "??\n??:0\n".
        child.stdin.write("\n")
        first = False
    result[addr] = records
  child.stdin.close()
  child.stdout.close()
  return result


def StripPC(addr):
  """Strips the Thumb bit a program counter address when appropriate.

  Args:
    addr: the program counter address

  Returns:
    The stripped program counter address.
  """
  global ARCH
  if ARCH == "arm":
    return addr & ~1
  return addr


def CallObjdumpForSet(lib, unique_addrs):
  """Use objdump to find out the names of the containing functions.

  Args:
    lib: library (or executable) pathname containing symbols
    unique_addrs: set of string hexidecimal addresses to find the functions for.

  Returns:
    A dictionary of the form {addr: (string symbol, offset)}.
  """
  if not lib:
    return None

  symbols = SYMBOLS_DIR + lib
  if not os.path.exists(symbols):
    return None

  symbols = SYMBOLS_DIR + lib
  if not os.path.exists(symbols):
    return None

  addrs = sorted(unique_addrs)
  start_addr_dec = str(StripPC(int(addrs[0], 16)))
  stop_addr_dec = str(StripPC(int(addrs[-1], 16)) + 8)
  cmd = [ToolPath("objdump"),
         "--section=.text",
         "--demangle",
         "--disassemble",
         "--start-address=" + start_addr_dec,
         "--stop-address=" + stop_addr_dec,
         symbols]

  # Function lines look like:
  #   000177b0 <android::IBinder::~IBinder()+0x2c>:
  # We pull out the address and function first. Then we check for an optional
  # offset. This is tricky due to functions that look like "operator+(..)+0x2c"
  func_regexp = re.compile("(^[a-f0-9]*) \<(.*)\>:$")
  offset_regexp = re.compile("(.*)\+0x([a-f0-9]*)")

  # A disassembly line looks like:
  #   177b2:	b510      	push	{r4, lr}
  asm_regexp = re.compile("(^[ a-f0-9]*):[ a-f0-0]*.*$")

  current_symbol = None    # The current function symbol in the disassembly.
  current_symbol_addr = 0  # The address of the current function.
  addr_index = 0  # The address that we are currently looking for.

  stream = subprocess.Popen(cmd, stdout=subprocess.PIPE).stdout
  result = {}
  for line in stream:
    # Is it a function line like:
    #   000177b0 <android::IBinder::~IBinder()>:
    components = func_regexp.match(line)
    if components:
      # This is a new function, so record the current function and its address.
      current_symbol_addr = int(components.group(1), 16)
      current_symbol = components.group(2)

      # Does it have an optional offset like: "foo(..)+0x2c"?
      components = offset_regexp.match(current_symbol)
      if components:
        current_symbol = components.group(1)
        offset = components.group(2)
        if offset:
          current_symbol_addr -= int(offset, 16)

    # Is it an disassembly line like:
    #   177b2:	b510      	push	{r4, lr}
    components = asm_regexp.match(line)
    if components:
      addr = components.group(1)
      target_addr = addrs[addr_index]
      i_addr = int(addr, 16)
      i_target = StripPC(int(target_addr, 16))
      if i_addr == i_target:
        result[target_addr] = (current_symbol, i_target - current_symbol_addr)
        addr_index += 1
        if addr_index >= len(addrs):
          break
  stream.close()

  return result


def CallCppFilt(mangled_symbol):
  cmd = [ToolPath("c++filt")]
  process = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
  process.stdin.write(mangled_symbol)
  process.stdin.write("\n")
  process.stdin.close()
  demangled_symbol = process.stdout.readline().strip()
  process.stdout.close()
  return demangled_symbol


def FormatSymbolWithOffset(symbol, offset):
  if offset == 0:
    return symbol
  return "%s+%d" % (symbol, offset)



class FindToolchainTests(unittest.TestCase):
  def assert_toolchain_found(self, abi):
    global ARCH
    ARCH = abi
    FindToolchain() # Will throw on failure.

  def test_toolchains_found(self):
    self.assert_toolchain_found("arm")
    self.assert_toolchain_found("arm64")
    self.assert_toolchain_found("mips")
    self.assert_toolchain_found("x86")
    self.assert_toolchain_found("x86_64")


if __name__ == '__main__':
    unittest.main()