scripts/gdb: add command to check list consistency

#

# 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")

def list_check(head):

    nb = 0

    c = head

    if (c.type != list_head.get_type()):

        raise gdb.GdbError('The argument should be of type (struct list_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)

    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()

    import linux.dmesg

    import linux.tasks

    import linux.cpus

    import linux.lists