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Windbg CLR基础小测 《第六篇》

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09/29
小程序：扫一扫查出行
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首先写一段代码如下：

namespace ConsoleApplication3
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello, Windbg!"); Console.ReadKey();
}
}
}

在Debug目录中启动该程序，然后在Debug中附加该进程。

0:007> .load C:/WINDOWS/Microsoft.NET/Framework/v4.0.30319/sos.dll
0:007> !dumpdomain
*** ERROR: Symbol file could not be found. Defaulted to export symbols for C:\Windows\Microsoft.NET\Framework\v4.0.30319\clr.dll -
PDB symbol for clr.dll not loaded
--------------------------------------
System Domain: 7106e898
LowFrequencyHeap: 7106ebbc
HighFrequencyHeap: 7106ec04
StubHeap: 7106ec4c
Stage: OPEN
Name: None
--------------------------------------
Shared Domain: 7106e4f0
LowFrequencyHeap: 7106ebbc
HighFrequencyHeap: 7106ec04
StubHeap: 7106ec4c
Stage: OPEN
Name: None
Assembly: 0051a1b8 [C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll]
ClassLoader: 00501660
Module Name
697e1000 C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll--------------------------------------
Domain 1: 004e78a8
LowFrequencyHeap: 004e7cfc
HighFrequencyHeap: 004e7d44
StubHeap: 004e7d8c
Stage: OPEN
SecurityDescriptor: 004e9388
Name: ConsoleApplication3.exe
Assembly: 0051a1b8 [C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll]
ClassLoader: 00501660
SecurityDescriptor: 0051a130
Module Name
697e1000 C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dllAssembly: 00521db8 [C:\Users\ChenZhuo\Documents\visual studio 2010\Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe]
ClassLoader: 005016c8
SecurityDescriptor: 00521d30
Module Name
00212eac C:\Users\ChenZhuo\Documents\visual studio 2010\Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe

从上面的输出结果中，有如下发现：

  1. .Net app默认情况下，会有三个AppDomain，其中分别是System Domain,Shared Domain和应用程序自己的Application Domain(就是上面的Domain1)；
  2. 一个domain内包含一个或若干个Assembly；

如果仅仅只是想查看一个domain，则可以使用如下命令，其输出结果与上面的结果一致：

:> !dumpdomain 004e78a8
--------------------------------------
Domain : 004e78a8
LowFrequencyHeap: 004e7cfc
HighFrequencyHeap: 004e7d44
StubHeap: 004e7d8c
Stage: OPEN
SecurityDescriptor: 004e9388
Name: ConsoleApplication3.exe
Assembly: 0051a1b8 [C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll]
ClassLoader:
SecurityDescriptor: 0051a130
Module Name
697e1000 C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dllAssembly: 00521db8 [C:\Users\ChenZhuo\Documents\visual studio \Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe]
ClassLoader: 005016c8
SecurityDescriptor: 00521d30
Module Name
00212eac C:\Users\ChenZhuo\Documents\visual studio \Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe

在上面的app domain中，我们可以看到包含了2个assembly，分别是mscorlib.dll和ConsoleApplication3.exe。

都有1个module。这里我们看ConsoleApplication3.exe。

看assembly信息，命令使用：!dumpassembly <assembly address>,我们执行：!dumpassembly <00212eac> 这个地址就在appdomain命令返回的程序集路径的左边。

:> !dumpassembly 00521db8
Parent Domain: 004e78a8
Name: C:\Users\ChenZhuo\Documents\visual studio \Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe
ClassLoader: 005016c8
Module Name
00212eac C:\Users\ChenZhuo\Documents\visual studio \Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe

注意：

  1. assembly包含了指向domain的信息，上面的004e78a8；
  2. assembly包含了一个或者若干个module；

这里只有一个module，我们继续看module里面包含啥。

命令!dumpmodule有一个有用的开关，是-mt <mt address>，我们跑一下看看：!dumpmodule -mt 1caa50

:> !dumpmodule -mt 00212eac
Name: C:\Users\ChenZhuo\Documents\visual studio \Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe
Attributes: PEFile
Assembly: 00521db8
LoaderHeap:
TypeDefToMethodTableMap:
TypeRefToMethodTableMap:
MethodDefToDescMap:
FieldDefToDescMap: 002100a4
MemberRefToDescMap: 002100a8
FileReferencesMap: 002100fc
AssemblyReferencesMap:
MetaData start address: 012a206c ( bytes)Types defined in this module MT TypeDef Name
------------------------------------------------------------------------------
002137c0 0x02000002 ConsoleApplication3.ProgramTypes referenced in this module MT TypeRef Name
------------------------------------------------------------------------------
69bb25e8 0x02000001 System.Object
69bb869c 0x02000013 System.Console

我们能发现两个重要的东西：

  1. 这个module里面包含的types，这里是我们的程序主入口点：ConsoleApplication3.Program；
  2. 这个module引用的types，这里是object和Console；

看上面的ConsoleApplication3.Program，这个type对应的MethodTable地址是：002137c0。我们可以继续看这个MethodTable包含啥东西：

:> !dumpmt 00212eac
00212eac is not a MethodTable
:> !dumpmt 002137c0
EEClass: 0021125c
Module: 00212eac
Name: ConsoleApplication3.Program
mdToken:
File: C:\Users\ChenZhuo\Documents\visual studio \Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe
BaseSize: 0xc
ComponentSize: 0x0
Slots in VTable:
Number of IFaces in IFaceMap:

这里有一些重要的东西可以看：

  1. EEClass，可以通过!dumpclass <class address>来查看这个class的信息。如：!dumpclass 0021125c；
  2. 包含了Module和name等信息；
  3. 包含了Method Description 信息；
  4. VTable里面的slots一共6个；

MethodTable只是一个入口表，它实际指向了一堆Method Description，那么我们可以用!dumpmt继续来查看，只不过参数要修改一下：!dumpmt -md 002137c0

:> !dumpmt 002137c0
EEClass: 0021125c
Module: 00212eac
Name: ConsoleApplication3.Program
mdToken:
File: C:\Users\ChenZhuo\Documents\visual studio \Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe
BaseSize: 0xc
ComponentSize: 0x0
Slots in VTable:
Number of IFaces in IFaceMap:
:> !dumpmt -md 00212eac
00212eac is not a MethodTable
:> !dumpmt -md 00212eac
00212eac is not a MethodTable
:> !dumpmt -md 00212eac
00212eac is not a MethodTable
:> !dumpmt -md 00212eac
00212eac is not a MethodTable
:> !dumpmt -md 002137c0
EEClass: 0021125c
Module: 00212eac
Name: ConsoleApplication3.Program
mdToken:
File: C:\Users\ChenZhuo\Documents\visual studio \Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe
BaseSize: 0xc
ComponentSize: 0x0
Slots in VTable:
Number of IFaces in IFaceMap:
--------------------------------------
MethodDesc Table
Entry MethodDe JIT Name
69accd88 697e60bc PreJIT System.Object.ToString()
69ac6a90 697e60c4 PreJIT System.Object.Equals(System.Object)
69ac6660 697e60e4 PreJIT System.Object.GetHashCode()
69b467c0 697e60f8 PreJIT System.Object.Finalize()
0021c015 002137b8 NONE ConsoleApplication3.Program..ctor()
002137ac JIT ConsoleApplication3.Program.Main(System.String[])

加了-md之后多出来了6个method description的信息，这就是那个Slots in VTable:6里面的6

对于每个方法，上表有一列JIT指明了CLR是否已经对该方法进行了编译动作。上面有一个方法是JIT过了，是那个Main函数，另外的4个CLR已经预先做了JIT（为什么？想想GAC和NGEN.EXE）。那么对于具体的方法是否做过了JIT，我们可以用命令：!dumpmd来看，比如看上面的Main方法，那么!dumpmd 002137c0

0:007> !dumpmt 002137c0
EEClass: 0021125c
Module: 00212eac
Name: ConsoleApplication3.Program
mdToken: 02000002
File: C:\Users\ChenZhuo\Documents\visual studio 2010\Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe
BaseSize: 0xc
ComponentSize: 0x0
Slots in VTable: 6
Number of IFaces in IFaceMap: 0
0:007> !dumpmt -md 00212eac
00212eac is not a MethodTable
0:007> !dumpmt -md 00212eac
00212eac is not a MethodTable
0:007> !dumpmt -md 00212eac
00212eac is not a MethodTable
0:007> !dumpmt -md 00212eac
00212eac is not a MethodTable
0:007> !dumpmt -md 002137c0
EEClass: 0021125c
Module: 00212eac
Name: ConsoleApplication3.Program
mdToken: 02000002
File: C:\Users\ChenZhuo\Documents\visual studio 2010\Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exe
BaseSize: 0xc
ComponentSize: 0x0
Slots in VTable: 6
Number of IFaces in IFaceMap: 0
--------------------------------------
MethodDesc Table
Entry MethodDe JIT Name
69accd88 697e60bc PreJIT System.Object.ToString()
69ac6a90 697e60c4 PreJIT System.Object.Equals(System.Object)
69ac6660 697e60e4 PreJIT System.Object.GetHashCode()
69b467c0 697e60f8 PreJIT System.Object.Finalize()
0021c015 002137b8 NONE ConsoleApplication3.Program..ctor()
00480050 002137ac JIT ConsoleApplication3.Program.Main(System.String[])
0:007> !dumpmd 00480050
00480050 is not a MethodDesc
0:007> !dumpmd 00480050
00480050 is not a MethodDesc
0:007> !dumpmd 002137ac
Method Name: ConsoleApplication3.Program.Main(System.String[])
Class: 0021125c
MethodTable: 002137c0
mdToken: 06000001
Module: 00212eac
IsJitted: yes
CodeAddr: 00480050
Transparency: Critical

上面最重要的结果就是有一个IsJitted的标志，这里是yes，表明它已经被compile过了，对于compile之后的native code，我们就可以用命令!u <m_codeoril>来观察。下命令：!u 00480050

0:007> !u 00480050
Normal JIT generated code
ConsoleApplication3.Program.Main(System.String[])
Begin 00480050, size 32
*** WARNING: Unable to verify checksum for C:\Users\ChenZhuo\Documents\visual studio 2010\Projects\ConsoleApplication3\ConsoleApplication3\bin\Debug\ConsoleApplication3.exeC:\Users\ChenZhuo\documents\visual studio 2010\Projects\ConsoleApplication3\ConsoleApplication3\Program.cs @ 14:
>>> 00480050 55 push ebp
00480051 8bec mov ebp,esp
00480053 83ec10 sub esp,10h
00480056 894dfc mov dword ptr [ebp-4],ecx
00480059 833d7831210000 cmp dword ptr ds:[213178h],0
00480060 7405 je 00480067
00480062 e8dcc98470 call clr!GetHistoryFileDirectory+0x8b758 (70ccca43) (JitHelp: CORINFO_HELP_DBG_IS_JUST_MY_CODE)
00480067 90 nopC:\Users\ChenZhuo\documents\visual studio 2010\Projects\ConsoleApplication3\ConsoleApplication3\Program.cs @ 15:
00480068 8b0d7021eb02 mov ecx,dword ptr ds:[2EB2170h] ("Hello, Windbg!")
*** WARNING: Unable to verify checksum for C:\Windows\assembly\NativeImages_v4.0.30319_32\mscorlib\045c9588954c3662d542b53f4462268b\mscorlib.ni.dll
0048006e e885796569 call mscorlib_ni+0x2f79f8 (69ad79f8) (System.Console.WriteLine(System.String), mdToken: 06000995)
00480073 90 nopC:\Users\ChenZhuo\documents\visual studio 2010\Projects\ConsoleApplication3\ConsoleApplication3\Program.cs @ 17:
00480074 8d4df0 lea ecx,[ebp-10h]
00480077 e82460d369 call mscorlib_ni+0x9d60a0 (6a1b60a0) (System.Console.ReadKey(), mdToken: 06000974)
0048007c 90 nopC:\Users\ChenZhuo\documents\visual studio 2010\Projects\ConsoleApplication3\ConsoleApplication3\Program.cs @ 18:
0048007d 90 nop
0048007e 8be5 mov esp,ebp
00480080 5d pop ebp
00480081 c3 ret

见到源代码了，字符串都看到了。

如果我们想看看StreamReader里面有哪些方法，应该用什么命令呢？

命令：!name2ee mscorlib_ni!System.IO.StreamReader.ReadBuffer

0:007> !name2ee mscorlib_ni!System.IO.StreamReader.ReadBuffer
Module: 697e1000
Assembly: mscorlib.dll
Token: 06004733
MethodDesc: 6985f3dc
Name: System.IO.StreamReader.ReadBuffer()
JITTED Code Address: 69b18020
-----------------------
Token: 0600473f
MethodDesc: 6985f460
Name: System.IO.StreamReader.ReadBuffer(Char[], Int32, Int32, Boolean ByRef)
JITTED Code Address: 69b763d0

拿到了Method Description的地址后执行：!dumpmd 6985f3dc

0:007> !dumpmd 6985f3dc
Method Name: System.IO.StreamReader.ReadBuffer()
Class: 6983e558
MethodTable: 69ba8fd0
mdToken: 06004733
Module: 697e1000
IsJitted: yes
CodeAddr: 69b18020
Transparency: Transparent

再执行!dumpmt -md 69ba8fd0，就可以得到这个class的所有method信息

:> !dumpmt -md 69ba8fd0
EEClass: 6983e558
Module: 697e1000
Name: System.IO.StreamReader
mdToken:
File: C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll
BaseSize: 0x40
ComponentSize: 0x0
Slots in VTable:
Number of IFaces in IFaceMap:
--------------------------------------
MethodDesc Table
Entry MethodDe JIT Name
69accd88 697e60bc PreJIT System.Object.ToString()
69ac6a90 697e60c4 PreJIT System.Object.Equals(System.Object)
69ac6660 697e60e4 PreJIT System.Object.GetHashCode()
69b467c0 697e60f8 PreJIT System.Object.Finalize()
69b7f310 PreJIT System.MarshalByRefObject.GetLifetimeService()
69aafd70 6987255c PreJIT System.MarshalByRefObject.InitializeLifetimeService()
69b6fdbc PreJIT System.MarshalByRefObject.CreateObjRef(System.Type)
69b1bbe0 6985f360 PreJIT System.IO.StreamReader.Close()
69b4ea80 6985ce74 PreJIT System.IO.TextReader.Dispose()
69b17a80 6985f368 PreJIT System.IO.StreamReader.Dispose(Boolean)... ...省略一部分