How to display user-mode stack of current kernel-mode context? - windbg

Question

Suppose I'm broken into Kernel Debugger, during a system call or an IOCTL that started from user mode. I want to see the full stack - starting from user mode and switching to kernel mode.
I know some of the pieces:
I can list all the processes with !process 0 0, and see the threads inside them. Or, drowse using !dml_proc.
If I know the current usermode thread, I can switch to it and see the whole start: !thread <usermode_thread> 15.
But how do I tie them together? Specifically:
How do I know the current usermode thread?
Can I retrieve it programatically, so I can have a one-liner !thread <some_magic> 15?

Answer 1

WinDbg keeps track of the current thread in both user mode as well as kernel mode in the pseudo register #$thread, and current process in the pseudo register #$proc.
To see current thread stack: !thread #$thread 0x1f.
This is the full stack, starting from _RtlUserThreadStart up to the last api which usually would be SwapContext() if the thread ceded execution.
To see current process with all its threads' stacks: !process #$proc 0x1f
here is a complete current threads stack spat out by both commands
!proc #$proc 1f as well as !thread #$thread 1f
the first will print the callstack of all threads of a specific process
the second will print the call stack of a specific currently running thread
you can notice the wait status as RUNNING on the first line of Threads output
:\>head -2 sample.txt
kd> !process #$proc 0x17
PROCESS 84efc748 SessionId: 0 Cid: 0470 Peb: 7ffdc000 ParentCid: 01e8
:\>wc -l sample.txt
517 sample.txt
:\>grep THREAD sample.txt
THREAD 84efcb60 Cid 0470.0474 Teb: 7ffdf000 Win32Thread: ff9f1c00 WAIT: (UserRequest) UserMode Non-Alertable
THREAD 84f166b8 Cid 0470.0478 Teb: 7ffde000 Win32Thread: 00000000 WAIT: (UserRequest) UserMode Alertable
THREAD 85303820 Cid 0470.0490 Teb: 7ffd9000 Win32Thread: 00000000 WAIT: (UserRequest) UserMode Non-Alertable
THREAD 85307bb0 Cid 0470.0494 Teb: 7ffd8000 Win32Thread: 00000000 WAIT: (UserRequest) UserMode Non-Alertable
THREAD 853064e8 Cid 0470.0498 Teb: 7ffd7000 Win32Thread: 00000000 WAIT: (UserRequest) UserMode Non-Alertable
THREAD 84e71d48 Cid 0470.049c Teb: 7ffd6000 Win32Thread: 00000000 WAIT: (UserRequest) UserMode Non-Alertable
THREAD 8530eb80 Cid 0470.04a8 Teb: 7ffda000 Win32Thread: 00000000 WAIT: (UserRequest) UserMode Non-Alertable
THREAD 85371030 Cid 0470.0538 Teb: 7ffd4000 Win32Thread: 00000000 WAIT: (WrQueue) UserMode Alertable
THREAD 8538ea08 Cid 0470.0588 Teb: 7ffad000 Win32Thread: 00000000 WAIT: (UserRequest) UserMode Non-Alertable
THREAD 853d6310 Cid 0470.05a4 Teb: 7ffaa000 Win32Thread: 00000000 WAIT: (WrQueue) UserMode Alertable
THREAD 8540fa78 Cid 0470.06bc Teb: 7ffaf000 Win32Thread: 00000000 WAIT: (UserRequest) UserMode Non-Alertable
THREAD 84173030 Cid 0470.0740 Teb: 7ffa6000 Win32Thread: 00000000 WAIT: (WrQueue) UserMode Non-Alertable
THREAD 84f77990 Cid 0470.0174 Teb: 7ffdd000 Win32Thread: 00000000 RUNNING on processor 0
THREAD 84f77990 Cid 0470.0174 Teb: 7ffdd000 Win32Thread: 00000000 RUNNING on processor 0
:\>grep !thread sample.txt
kd> !thread #$thread 1f
:\>grep -A 2 !thread sample.txt
kd> !thread #$thread 1f
THREAD 84f77990 Cid 0470.0174 Teb: 7ffdd000 Win32Thread: 00000000 RUNNING on processor 0
Not impersonating
:\>
the full call stack of a currently running thread broken on NtDeviceIoControlFile
kd> !thread #$thread 1f
THREAD 84f77990 Cid 0470.0174 Teb: 7ffdd000 Win32Thread: 00000000 RUNNING on processor 0
Not impersonating
DeviceMap 919b0008
Owning Process 84efc748 Image: svchost.exe
Attached Process N/A Image: N/A
Wait Start TickCount 49461 Ticks: 1 (0:00:00:00.010)
Context Switch Count 659 IdealProcessor: 0
UserTime 00:00:00.040
KernelTime 00:00:03.314
Win32 Start Address ntdll!TppWorkerThread (0x770403e7)
Stack Init 8c0e3fd0 Current 8c0e3bf8 Base 8c0e4000 Limit 8c0e1000 Call 00000000
Priority 8 BasePriority 8 PriorityDecrement 0 IoPriority 2 PagePriority 5
ChildEBP RetAddr
8c0e3d04 8283787a nt!NtDeviceIoControlFile
8c0e3d04 770570b4 nt!KiFastCallEntry+0x12a (FPO: [0,3] TrapFrame # 8c0e3d34)
0292f518 77055864 ntdll!KiFastSystemCallRet (FPO: [0,0,0])
0292f51c 76dd14c9 ntdll!ZwDeviceIoControlFile+0xc (FPO: [10,0,0])
0292f560 76dd15f9 NSI!NsiIoctl+0x5d (FPO: [Non-Fpo])
0292f584 76dd15c7 NSI!NsiEnumerateObjectsAllParametersEx+0x23 (FPO: [Non-Fpo])
0292f5d0 718718e2 NSI!NsiEnumerateObjectsAllParameters+0x79 (FPO: [Non-Fpo])
0292f620 71871858 ncsi!CNcsiNsiTable::AllocateAndGetTable+0x51 (FPO: [Non-Fpo])
0292f644 718717c6 ncsi!UpdateInterfaceStatsByFamily+0xb0 (FPO: [Non-Fpo])
0292f664 71871e49 ncsi!UpdateInterfaceStats+0x26 (FPO: [Non-Fpo])
0292f694 71871d4e ncsi!PassiveProbe+0x6f (FPO: [Non-Fpo])
0292f6f4 718715d5 ncsi!NcsiUpdateConnectivityStatusList+0x4a1 (FPO: [Non-Fpo])
0292f6f8 7704112c ncsi!NcsiUpdateConnectivityStatusListTimer+0x5 (FPO: [3,0,0])
0292f71c 77040842 ntdll!TppTimerpExecuteCallback+0x10f (FPO: [Non-Fpo])
0292f87c 756f3c45 ntdll!TppWorkerThread+0x572 (FPO: [Non-Fpo])
0292f888 770737f5 kernel32!BaseThreadInitThunk+0xe (FPO: [Non-Fpo])
0292f8c8 770737c8 ntdll!__RtlUserThreadStart+0x70 (FPO: [Non-Fpo])
0292f8e0 00000000 ntdll!_RtlUserThreadStart+0x1b (FPO: [Non-Fpo])