## gdb helper commands and functions for Linux kernel debugging##  list tools## Copyright (c) Thiebaud Weksteen, 2015## Authors:#  Thiebaud Weksteen <thiebaud@weksteen.fr>## This work is licensed under the terms of the GNU GPL version 2.# import gdb from linux import utils list_head = utils.CachedType("struct list_head")hlist_head = utils.CachedType("struct hlist_head")hlist_node = utils.CachedType("struct hlist_node")  def list_for_each(head):    if head.type == list_head.get_type().pointer():        head = head.dereference()    elif head.type != list_head.get_type():        raise TypeError("Must be struct list_head not {}"                           .format(head.type))     if head['next'] == 0:        gdb.write("list_for_each: Uninitialized list '{}' treated as empty\n"                     .format(head.address))        return     node = head['next'].dereference()    while node.address != head.address:        yield node.address        node = node['next'].dereference()  def list_for_each_entry(head, gdbtype, member):    for node in list_for_each(head):        yield utils.container_of(node, gdbtype, member)  def hlist_for_each(head):    if head.type == hlist_head.get_type().pointer():        head = head.dereference()    elif head.type != hlist_head.get_type():        raise TypeError("Must be struct hlist_head not {}"                           .format(head.type))     node = head['first'].dereference()    while node.address:        yield node.address        node = node['next'].dereference()  def hlist_for_each_entry(head, gdbtype, member):    for node in hlist_for_each(head):        yield utils.container_of(node, gdbtype, member)  def list_check(head):    nb = 0    if (head.type == list_head.get_type().pointer()):        head = head.dereference()    elif (head.type != list_head.get_type()):        raise gdb.GdbError('argument must be of type (struct list_head [*])')    c = head    try:        gdb.write("Starting with: {}\n".format(c))    except gdb.MemoryError:        gdb.write('head is not accessible\n')        return    while True:        p = c['prev'].dereference()        n = c['next'].dereference()        try:            if p['next'] != c.address:                gdb.write('prev.next != current: '                          'current@{current_addr}={current} '                          'prev@{p_addr}={p}\n'.format(                              current_addr=c.address,                              current=c,                              p_addr=p.address,                              p=p,                          ))                return        except gdb.MemoryError:            gdb.write('prev is not accessible: '                      'current@{current_addr}={current}\n'.format(                          current_addr=c.address,                          current=c                      ))            return        try:            if n['prev'] != c.address:                gdb.write('next.prev != current: '                          'current@{current_addr}={current} '                          'next@{n_addr}={n}\n'.format(                              current_addr=c.address,                              current=c,                              n_addr=n.address,                              n=n,                          ))                return        except gdb.MemoryError:            gdb.write('next is not accessible: '                      'current@{current_addr}={current}\n'.format(                          current_addr=c.address,                          current=c                      ))            return        c = n        nb += 1        if c == head:            gdb.write("list is consistent: {} node(s)\n".format(nb))            return  class LxListChk(gdb.Command):    """Verify a list consistency"""     def __init__(self):        super(LxListChk, self).__init__("lx-list-check", gdb.COMMAND_DATA,                                        gdb.COMPLETE_EXPRESSION)     def invoke(self, arg, from_tty):        argv = gdb.string_to_argv(arg)        if len(argv) != 1:            raise gdb.GdbError("lx-list-check takes one argument")        list_check(gdb.parse_and_eval(argv[0]))  LxListChk()