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Inspect a 32 bit Process Dump Generated by a 64 bit Debugger

  • 아티클

64 bit Windows can run both 32 bit process and 64 bit process. For debugging though, you want to use 32 bit debugger to debug 32 bit process, and 64 bit debugger for 64 bit process. Otherwise it won’t be pretty.

Occasionally, I receive a 32 bit process dump generated by a 64 bit debugger.

When load some dump in the debugger, this is how it looks like:

0:020> .sympath SRV*c:\websymbols* https://msdl.microsoft.com/download/symbols
Symbol search path is: SRV*c:\websymbols*https://msdl.microsoft.com/download/symbols

  20 Id: 1994.15f4 Suspend: 1 Teb: 00000000`7efa4000 Unfrozen
RetAddr : Args to Child : Call Site
00000000`78b84191 : 00000023`7d61c918 00000000`00000023 00000000`00000202 00000000`0518fffc : wow64cpu!CpupSyscallStub+0x9
00000000`6b006a5a : 00000000`00000003 00000000`00000000 00000000`00000000 00000000`051cf7d0 : wow64cpu!Thunk2ArgNSpNSpReloadState+0x21
00000000`6b005e0d : 00000000`051cfd00 00000000`051cf1d0 00000000`051cf7d0 00000000`00000000 : wow64!RunCpuSimulation+0xa
00000000`77f109f0 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`7efdf000 : wow64!Wow64LdrpInitialize+0x2ed
00000000`77ef30a5 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : ntdll!LdrpInitialize+0x2aa
00000000`7d4d1504 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : ntdll!KiUserApcDispatcher+0x15
00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : kernel32!BaseThreadStartThunk
00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : 0x0
00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : 0x0
00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 0001002f`00000000 : 0x0
00000000`00000000 : 00000000`00000000 00000000`00000000 0001002f`00000000 00000000`00000000 : 0x0
00000000`00000000 : 00000000`00000000 0001002f`00000000 00000000`00000000 00000000`00000000 : 0x0
00000000`00000000 : 0001002f`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : 0x0
0001002f`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : 0x0
00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : 0x1002f`00000000
00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : 0x0
00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : 0x0
00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : 0x0
00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : 0x0
00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : 0x0

I do not know if you can make sense of it. I cannot.

Fortunately, Windows debugger allows you to change the target processor type. Here is how it works:

0:020> .effmach x86
Effective machine: x86 compatible (x86)
0:020:x86> .load wow64exts

  20 Id: 1994.15f4 Suspend: 1 Teb: 00000000`7efa4000 Unfrozen
ChildEBP RetAddr Args to Child
0518ff0c 7d4d0ec5 00000000 0518ff4c 7d4d8bfa ntdll_7d600000!ZwDelayExecution+0x15
0518ff74 7d4d14ef 0000ea60 00000000 0518ffac kernel32!SleepEx+0x68
0518ff84 776bbb0f 0000ea60 083e6ca8 776bbab4 kernel32!Sleep+0xf
0518ff90 776bbab4 00000000 00000000 083e6ca8 ole32!CROIDTable::WorkerThreadLoop+0x14
0518ffac 776b1704 00000000 0518ffec 7d4dfe21 ole32!CRpcThread::WorkerLoop+0x26
0518ffb8 7d4dfe21 083e6ca8 00000000 00000000 ole32!CRpcThreadCache::RpcWorkerThreadEntry+0x20
0518ffec 00000000 776b16e4 083e6ca8 00000000 kernel32!BaseThreadStart+0x34

Much better, isn’t it?

For best result though, please use 32 bit debugger to generate the dump for a 32 bit process.

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