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#
# gdb helper commands and functions for Linux kernel debugging
#
# common utilities
#
# Copyright (c) Siemens AG, 2011-2013
#
# Authors:
# Jan Kiszka <jan.kiszka@siemens.com>
#
# This work is licensed under the terms of the GNU GPL version 2.
#
import gdb
class CachedType:
def __init__(self, name):
self._type = None
self._name = name
def _new_objfile_handler(self, event):
self._type = None
gdb.events.new_objfile.disconnect(self._new_objfile_handler)
def get_type(self):
if self._type is None:
self._type = gdb.lookup_type(self._name)
if self._type is None:
raise gdb.GdbError(
"cannot resolve type '{0}'".format(self._name))
if hasattr(gdb, 'events') and hasattr(gdb.events, 'new_objfile'):
gdb.events.new_objfile.connect(self._new_objfile_handler)
return self._type
long_type = CachedType("long")
def get_long_type():
global long_type
return long_type.get_type()
def offset_of(typeobj, field):
element = gdb.Value(0).cast(typeobj)
return int(str(element[field].address).split()[0], 16)
def container_of(ptr, typeobj, member):
return (ptr.cast(get_long_type()) -
offset_of(typeobj, member)).cast(typeobj)
class ContainerOf(gdb.Function):
"""Return pointer to containing data structure.
$container_of(PTR, "TYPE", "ELEMENT"): Given PTR, return a pointer to the
data structure of the type TYPE in which PTR is the address of ELEMENT.
Note that TYPE and ELEMENT have to be quoted as strings."""
def __init__(self):
super(ContainerOf, self).__init__("container_of")
def invoke(self, ptr, typename, elementname):
return container_of(ptr, gdb.lookup_type(typename.string()).pointer(),
elementname.string())
ContainerOf()
BIG_ENDIAN = 0
LITTLE_ENDIAN = 1
target_endianness = None
def get_target_endianness():
global target_endianness
if target_endianness is None:
endian = gdb.execute("show endian", to_string=True)
if "little endian" in endian:
target_endianness = LITTLE_ENDIAN
elif "big endian" in endian:
target_endianness = BIG_ENDIAN
else:
raise gdb.GdgError("unknown endianness '{0}'".format(endian))
return target_endianness
def read_u16(buffer):
if get_target_endianness() == LITTLE_ENDIAN:
return ord(buffer[0]) + (ord(buffer[1]) << 8)
else:
return ord(buffer[1]) + (ord(buffer[0]) << 8)
def read_u32(buffer):
if get_target_endianness() == LITTLE_ENDIAN:
return read_u16(buffer[0:2]) + (read_u16(buffer[2:4]) << 16)
else:
return read_u16(buffer[2:4]) + (read_u16(buffer[0:2]) << 16)
def read_u64(buffer):
if get_target_endianness() == LITTLE_ENDIAN:
return read_u32(buffer[0:4]) + (read_u32(buffer[4:8]) << 32)
else:
return read_u32(buffer[4:8]) + (read_u32(buffer[0:4]) << 32)
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