## gdb helper commands and functions for Linux kernel debugging##  task & thread tools## 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 from linux import utils, lists  task_type = utils.CachedType("struct task_struct")  def task_lists():    task_ptr_type = task_type.get_type().pointer()    init_task = gdb.parse_and_eval("init_task").address    t = init_task     while True:        thread_head = t['signal']['thread_head']        for thread in lists.list_for_each_entry(thread_head, task_ptr_type, 'thread_node'):            yield thread         t = utils.container_of(t['tasks']['next'],                               task_ptr_type, "tasks")        if t == init_task:            return  def get_task_by_pid(pid):    for task in task_lists():        if int(task['pid']) == pid:            return task    return None  class LxTaskByPidFunc(gdb.Function):    """Find Linux task by PID and return the task_struct variable. $lx_task_by_pid(PID): Given PID, iterate over all tasks of the target andreturn that task_struct variable which PID matches."""     def __init__(self):        super(LxTaskByPidFunc, self).__init__("lx_task_by_pid")     def invoke(self, pid):        task = get_task_by_pid(pid)        if task:            return task.dereference()        else:            raise gdb.GdbError("No task of PID " + str(pid))  LxTaskByPidFunc()  class LxPs(gdb.Command):    """Dump Linux tasks."""     def __init__(self):        super(LxPs, self).__init__("lx-ps", gdb.COMMAND_DATA)     def invoke(self, arg, from_tty):        gdb.write("{:>10} {:>12} {:>7}\n".format("TASK", "PID", "COMM"))        for task in task_lists():            gdb.write("{} {:^5} {}\n".format(                task.format_string().split()[0],                task["pid"].format_string(),                task["comm"].string()))  LxPs()  thread_info_type = utils.CachedType("struct thread_info")  def get_thread_info(task):    thread_info_ptr_type = thread_info_type.get_type().pointer()    if task.type.fields()[0].type == thread_info_type.get_type():        return task['thread_info']    thread_info = task['stack'].cast(thread_info_ptr_type)    return thread_info.dereference()  class LxThreadInfoFunc (gdb.Function):    """Calculate Linux thread_info from task variable. $lx_thread_info(TASK): Given TASK, return the corresponding thread_infovariable."""     def __init__(self):        super(LxThreadInfoFunc, self).__init__("lx_thread_info")     def invoke(self, task):        return get_thread_info(task)  LxThreadInfoFunc()  class LxThreadInfoByPidFunc (gdb.Function):    """Calculate Linux thread_info from task variable found by pid $lx_thread_info_by_pid(PID): Given PID, return the corresponding thread_infovariable."""     def __init__(self):        super(LxThreadInfoByPidFunc, self).__init__("lx_thread_info_by_pid")     def invoke(self, pid):        task = get_task_by_pid(pid)        if task:            return get_thread_info(task.dereference())        else:            raise gdb.GdbError("No task of PID " + str(pid))  LxThreadInfoByPidFunc()