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
  70 ContainerOf()
  71
  72
  73 BIG_ENDIAN = 0
  74 LITTLE_ENDIAN = 1
  75 target_endianness = None
  76
  77
  78 def get_target_endianness():
  79     global target_endianness
  80     if target_endianness is None:
  81         endian = gdb.execute("show endian", to_string=True)
  82         if "little endian" in endian:
  83             target_endianness = LITTLE_ENDIAN
  84         elif "big endian" in endian:
  85             target_endianness = BIG_ENDIAN
  86         else:
  87             raise gdb.GdbError("unknown endianness '{0}'".format(str(endian)))
  88     return target_endianness
  89
  90
  91 def read_memoryview(inf, start, length):
  92     return memoryview(inf.read_memory(start, length))
  93
  94
  95 def read_u16(buffer):
  96     value = [0, 0]
  97
  98     if type(buffer[0]) is str:
  99         value[0] = ord(buffer[0])
 100         value[1] = ord(buffer[1])
 101     else:
 102         value[0] = buffer[0]
 103         value[1] = buffer[1]
 104
 105     if get_target_endianness() == LITTLE_ENDIAN:
 106         return value[0] + (value[1] << 8)
 107     else:
 108         return value[1] + (value[0] << 8)
 109
 110
 111 def read_u32(buffer):
 112     if get_target_endianness() == LITTLE_ENDIAN:
 113         return read_u16(buffer[0:2]) + (read_u16(buffer[2:4]) << 16)
 114     else:
 115         return read_u16(buffer[2:4]) + (read_u16(buffer[0:2]) << 16)
 116
 117
 118 def read_u64(buffer):
 119     if get_target_endianness() == LITTLE_ENDIAN:
 120         return read_u32(buffer[0:4]) + (read_u32(buffer[4:8]) << 32)
 121     else:
 122         return read_u32(buffer[4:8]) + (read_u32(buffer[0:4]) << 32)
 123
 124
 125 target_arch = None
 126
 127
 128 def is_target_arch(arch):
 129     if hasattr(gdb.Frame, 'architecture'):
 130         return arch in gdb.newest_frame().architecture().name()
 131     else:
 132         global target_arch
 133         if target_arch is None:
 134             target_arch = gdb.execute("show architecture", to_string=True)
 135         return arch in target_arch
 136
 137
 138 GDBSERVER_QEMU = 0
 139 GDBSERVER_KGDB = 1
 140 gdbserver_type = None
 141
 142
 143 def get_gdbserver_type():
 144     def exit_handler(event):
 145         global gdbserver_type
 146         gdbserver_type = None
 147         gdb.events.exited.disconnect(exit_handler)
 148
 149     def probe_qemu():
 150         try:
 151             return gdb.execute("monitor info version", to_string=True) != ""
 152         except gdb.error:
 153             return False
 154
 155     def probe_kgdb():
 156         try:
 157             thread_info = gdb.execute("info thread 2", to_string=True)
 158             return "shadowCPU0" in thread_info
 159         except gdb.error:
 160             return False
 161
 162     global gdbserver_type
 163     if gdbserver_type is None:
 164         if probe_qemu():
 165             gdbserver_type = GDBSERVER_QEMU
 166         elif probe_kgdb():
 167             gdbserver_type = GDBSERVER_KGDB
 168         if gdbserver_type is not None and hasattr(gdb, 'events'):
 169             gdb.events.exited.connect(exit_handler)
 170     return gdbserver_type
 171
 172
 173 def gdb_eval_or_none(expresssion):
 174     try:
 175         return gdb.parse_and_eval(expresssion)
 176     except gdb.error:
 177         return None
 178
 179
 180 def dentry_name(d):
 181     parent = d['d_parent']
 182     if parent == d or parent == 0:
 183         return ""
 184     p = dentry_name(d['d_parent']) + "/"
 185     return p + d['d_iname'].string()