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 <[email protected]> 10# 11# This work is licensed under the terms of the GNU GPL version 2. 12# 13 14import gdb 15 16 17class 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 37long_type = CachedType("long") 38 39 40def get_long_type(): 41 global long_type 42 return long_type.get_type() 43 44 45def offset_of(typeobj, field): 46 element = gdb.Value(0).cast(typeobj) 47 return int(str(element[field].address).split()[0], 16) 48 49 50def container_of(ptr, typeobj, member): 51 return (ptr.cast(get_long_type()) - 52 offset_of(typeobj, member)).cast(typeobj) 53 54 55class ContainerOf(gdb.Function): 56 """Return pointer to containing data structure. 57 58$container_of(PTR, "TYPE", "ELEMENT"): Given PTR, return a pointer to the 59data structure of the type TYPE in which PTR is the address of ELEMENT. 60Note 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 69ContainerOf() 70