scripts/gdb/linux/utils.py

   1 #
   2 # gdb helper commands and functions for Linux kernel debugging
   3 #
   4 #  common utilities
   5 #
   6 # Copyright (c) Siemens AG, 2011-2013
   7 #
   8 # Authors:
   9 #  Jan Kiszka <jan.kiszka@siemens.com>
  10 #
  11 # This work is licensed under the terms of the GNU GPL version 2.
  12 #
  13
  14 import gdb
  15
  16
  17 class CachedType:
  18     def __init__(self, name):
  19         self._type = None
  20         self._name = name
  21
  22     def _new_objfile_handler(self, event):
  23         self._type = None
  24         gdb.events.new_objfile.disconnect(self._new_objfile_handler)
  25
  26     def get_type(self):
  27         if self._type is None:
  28             self._type = gdb.lookup_type(self._name)
  29             if self._type is None:
  30                 raise gdb.GdbError(
  31                     "cannot resolve type '{0}'".format(self._name))
  32             if hasattr(gdb, 'events') and hasattr(gdb.events, 'new_objfile'):
  33                 gdb.events.new_objfile.connect(self._new_objfile_handler)
  34         return self._type
  35
  36
  37 long_type = CachedType("long")
  38
  39
  40 def get_long_type():
  41     global long_type
  42     return long_type.get_type()
  43
  44
  45 def offset_of(typeobj, field):
  46     element = gdb.Value(0).cast(typeobj)
  47     return int(str(element[field].address).split()[0], 16)
  48
  49
  50 def container_of(ptr, typeobj, member):
  51     return (ptr.cast(get_long_type()) -
  52             offset_of(typeobj, member)).cast(typeobj)
  53
  54
  55 class ContainerOf(gdb.Function):
  56     """Return pointer to containing data structure.
  57
  58 $container_of(PTR, "TYPE", "ELEMENT"): Given PTR, return a pointer to the
  59 data structure of the type TYPE in which PTR is the address of ELEMENT.
  60 Note that TYPE and ELEMENT have to be quoted as strings."""
  61
  62     def __init__(self):
  63         super(ContainerOf, self).__init__("container_of")
  64
  65     def invoke(self, ptr, typename, elementname):
  66         return container_of(ptr, gdb.lookup_type(typename.string()).pointer(),
  67                             elementname.string())
  68
  69 ContainerOf()
  70
  71
  72 BIG_ENDIAN = 0
  73 LITTLE_ENDIAN = 1
  74 target_endianness = None
  75
  76
  77 def get_target_endianness():
  78     global target_endianness
  79     if target_endianness is None:
  80         endian = gdb.execute("show endian", to_string=True)
  81         if "little endian" in endian:
  82             target_endianness = LITTLE_ENDIAN
  83         elif "big endian" in endian:
  84             target_endianness = BIG_ENDIAN
  85         else:
  86             raise gdb.GdbError("unknown endianness '{0}'".format(str(endian)))
  87     return target_endianness
  88
  89
  90 def read_memoryview(inf, start, length):
  91     return memoryview(inf.read_memory(start, length))
  92
  93
  94 def read_u16(buffer):
  95     value = [0, 0]
  96
  97     if type(buffer[0]) is str:
  98         value[0] = ord(buffer[0])
  99         value[1] = ord(buffer[1])
 100     else:
 101         value[0] = buffer[0]
 102         value[1] = buffer[1]
 103
 104     if get_target_endianness() == LITTLE_ENDIAN:
 105         return value[0] + (value[1] << 8)
 106     else:
 107         return value[1] + (value[0] << 8)
 108
 109
 110 def read_u32(buffer):
 111     if get_target_endianness() == LITTLE_ENDIAN:
 112         return read_u16(buffer[0:2]) + (read_u16(buffer[2:4]) << 16)
 113     else:
 114         return read_u16(buffer[2:4]) + (read_u16(buffer[0:2]) << 16)
 115
 116
 117 def read_u64(buffer):
 118     if get_target_endianness() == LITTLE_ENDIAN:
 119         return read_u32(buffer[0:4]) + (read_u32(buffer[4:8]) << 32)
 120     else:
 121         return read_u32(buffer[4:8]) + (read_u32(buffer[0:4]) << 32)
 122
 123
 124 target_arch = None
 125
 126
 127 def is_target_arch(arch):
 128     if hasattr(gdb.Frame, 'architecture'):
 129         return arch in gdb.newest_frame().architecture().name()
 130     else:
 131         global target_arch
 132         if target_arch is None:
 133             target_arch = gdb.execute("show architecture", to_string=True)
 134         return arch in target_arch
 135
 136
 137 GDBSERVER_QEMU = 0
 138 GDBSERVER_KGDB = 1
 139 gdbserver_type = None
 140
 141
 142 def get_gdbserver_type():
 143     def exit_handler(event):
 144         global gdbserver_type
 145         gdbserver_type = None
 146         gdb.events.exited.disconnect(exit_handler)
 147
 148     def probe_qemu():
 149         try:
 150             return gdb.execute("monitor info version", to_string=True) != ""
 151         except:
 152             return False
 153
 154     def probe_kgdb():
 155         try:
 156             thread_info = gdb.execute("info thread 2", to_string=True)
 157             return "shadowCPU0" in thread_info
 158         except:
 159             return False
 160
 161     global gdbserver_type
 162     if gdbserver_type is None:
 163         if probe_qemu():
 164             gdbserver_type = GDBSERVER_QEMU
 165         elif probe_kgdb():
 166             gdbserver_type = GDBSERVER_KGDB
 167         if gdbserver_type is not None and hasattr(gdb, 'events'):
 168             gdb.events.exited.connect(exit_handler)
 169     return gdbserver_type
 170
 171
 172 def gdb_eval_or_none(expresssion):
 173     try:
 174         return gdb.parse_and_eval(expresssion)
 175     except:
 176         return None
 177
 178
 179 def dentry_name(d):
 180     parent = d['d_parent']
 181     if parent == d or parent == 0:
 182         return ""
 183     p = dentry_name(d['d_parent']) + "/"
 184     return p + d['d_iname'].string()