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Re: Mavericks kernel panic debugging
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Re: Mavericks kernel panic debugging

  • Subject: Re: Mavericks kernel panic debugging
  • From: jas <email@hidden>
  • Date: Mon, 13 Jan 2014 22:40:19 -0500
Awesome - thanks Shantonu.  Might make a good a tech note, but looks like most of the info you covered here is on the llvm site.  Thanks!

On Jan 12, 2014, at 1:16 PM, Shantonu Sen <email@hidden> wrote:

Generally you want to use the information at <http://lldb.llvm.org/symbolication.html> for offline symbolication.

For example, for the panic log reported at <https://discussions.apple.com/message/23642509#23642509>, you would download the kernel debug kit for 13A603 and Xcode 5.0.x and do:

$ cd /Volumes/KernelDebugKit/
$ lldb
(lldb) target create --no-dependents --arch x86_64 mach_kernel
warning: 'mach_kernel' contains a debug script. To run this script in this debug session:

    command script import "/Volumes/KernelDebugKit/mach_kernel.dSYM/Contents/Resources/Python/mach_kernel.py"

To run all discovered debug scripts in this session:

    settings set target.load-script-from-symbol-file true

Current executable set to 'mach_kernel' (x86_64).
(lldb) settings set target.load-script-from-symbol-file true
Loading kernel debugging from /Volumes/KernelDebugKit/mach_kernel.dSYM/Contents/Resources/Python/mach_kernel.py
LLDB version lldb-XXX
settings set target.process.python-os-plugin-path "/Volumes/KernelDebugKit/mach_kernel.dSYM/Contents/Resources/Python/lldbmacros/core/operating_system.py"
command script import "/Volumes/KernelDebugKit/mach_kernel.dSYM/Contents/Resources/Python/lldbmacros/xnu.py"
xnu debug macros loaded successfully. Run showlldbtypesummaries to enable type summaries.


(lldb) target modules add IOAudioFamily.kext/Contents/MacOS/IOAudioFamily
(lldb) target modules add IOUSBFamily.kext/Contents/MacOS/IOUSBFamily
(lldb) image list
[  0] 1D9369E3-D0A5-31B6-8D16-BFFBBB390393 0xffffff8000200000 /Volumes/KernelDebugKit/mach_kernel 
      /Volumes/KernelDebugKit/mach_kernel.dSYM/Contents/Resources/DWARF/mach_kernel
[  1] 5077FB4F-0903-3D79-8280-5B2341E93BF3 0x0000000000000000 /Volumes/KernelDebugKit/IOAudioFamily.kext/Contents/MacOS/IOAudioFamily 
      /Volumes/KernelDebugKit/IOAudioFamily.kext.dSYM/Contents/Resources/DWARF/IOAudioFamily
[  2] 972D3024-AF9C-3E09-A9EC-D9AB2A559B38 0x0000000000000000 /Volumes/KernelDebugKit/IOUSBFamily.kext/Contents/MacOS/IOUSBFamily 
      /Volumes/KernelDebugKit/IOUSBFamily.kext.dSYM/Contents/Resources/DWARF/IOUSBFamily
(lldb)

At this point, the images are loaded but all at their default load address. Then do

(lldb) target modules load --file mach_kernel --slide 0x000000000b600000
(lldb) target modules load --file IOAudioFamily __TEXT 0xffffff7f8c135000
section '__TEXT' loaded at 0xffffff7f8c135000
(lldb) target modules load --file IOUSBFamily __TEXT 0xffffff7f8c19a000
section '__TEXT' loaded at 0xffffff7f8c19a000
(lldb) image list
[  0] 1D9369E3-D0A5-31B6-8D16-BFFBBB390393 0xffffff800b800000 /Volumes/KernelDebugKit/mach_kernel 
      /Volumes/KernelDebugKit/mach_kernel.dSYM/Contents/Resources/DWARF/mach_kernel
[  1] 5077FB4F-0903-3D79-8280-5B2341E93BF3 0xffffff7f8c135000 /Volumes/KernelDebugKit/IOAudioFamily.kext/Contents/MacOS/IOAudioFamily 
      /Volumes/KernelDebugKit/IOAudioFamily.kext.dSYM/Contents/Resources/DWARF/IOAudioFamily
[  2] 972D3024-AF9C-3E09-A9EC-D9AB2A559B38 0xffffff7f8c19a000 /Volumes/KernelDebugKit/IOUSBFamily.kext/Contents/MacOS/IOUSBFamily 
      /Volumes/KernelDebugKit/IOUSBFamily.kext.dSYM/Contents/Resources/DWARF/IOUSBFamily
(lldb)

We have the explicit slide for the kernel (and all segments slide together), so we can use --slide for it. Then you can use "image lookup” and “source list”, etc., to map addresses in the report to line numbers. Addresses that don’t resolve are in the 3rd party kext involved in this panic.

(lldb) image lookup -a 0xffffff800b8d6aa7
      Address: mach_kernel[0xffffff80002d6aa7] (mach_kernel.__TEXT.__text + 871079)
      Summary: mach_kernel`call_continuation + 23
(lldb) image lookup -a 0xffffff800b84a15a
      Address: mach_kernel[0xffffff800024a15a] (mach_kernel.__TEXT.__text + 295258)
      Summary: mach_kernel`thread_call_thread + 506 at thread_call.c:1218
(lldb) image lookup -a 0xffffff7f8debaa62
(lldb) image lookup -a 0xffffff800bcae4b3
      Address: mach_kernel[0xffffff80006ae4b3] (mach_kernel.__TEXT.__text + 4900019)
      Summary: mach_kernel`IOCommandGate::runAction(int (*)(OSObject*, void*, void*, void*, void*), void*, void*, void*, void*) + 355 at IOCommandGate.cpp:190
(lldb) image lookup -a 0xffffff7f8debbaf4
(lldb) image lookup -a 0xffffff7f8c139634
      Address: IOAudioFamily[0x0000000000004634] (IOAudioFamily.__TEXT.__text + 14516)
      Summary: IOAudioFamily`IOAudioDevice::activateAudioEngine(IOAudioEngine*, bool) + 94 at IOAudioDevice.cpp:903
(lldb) image lookup -a 0xffffff7f8c13aa20
      Address: IOAudioFamily[0x0000000000005a20] (IOAudioFamily.__TEXT.__text + 19616)
      Summary: IOAudioFamily`IOAudioEngine::start(IOService*) + 56 at IOAudioEngine.cpp:552
(lldb) image lookup -a 0xffffff7f8debe2a9
(lldb) image lookup -a 0xffffff7f8c13aadc
      Address: IOAudioFamily[0x0000000000005adc] (IOAudioFamily.__TEXT.__text + 19804)
      Summary: IOAudioFamily`IOAudioEngine::start(IOService*, IOAudioDevice*) + 176 at IOAudioEngine.cpp:584
(lldb) image lookup -a 0xffffff7f8debee0f
(lldb) image lookup -a 0xffffff7f8debe166
(lldb) image lookup -a 0xffffff800b8f3606
      Address: mach_kernel[0xffffff80002f3606] (mach_kernel.__TEXT.__text + 988678)
      Summary: mach_kernel`trap_from_kernel + 38
(lldb) image lookup -a 0xffffff800b8dc19e
      Address: mach_kernel[0xffffff80002dc19e] (mach_kernel.__TEXT.__text + 893342)
      Summary: mach_kernel`kernel_trap + 2046 at trap.c:790
(lldb) image lookup -a 0xffffff800b822f69
      Address: mach_kernel[0xffffff8000222f69] (mach_kernel.__TEXT.__text + 135017)
      Summary: mach_kernel`panic + 201 at debug.c:353
(lldb) 

Shantonu

On Jan 12, 2014, at 9:08 AM, Jeff Schindler <email@hidden> wrote:

I'm just trying to decipher a panic log, as defined in the "Isolating the crash" section here for gdb: https://developer.apple.com/library/mac/technotes/tn2063/_index.html#//apple_ref/doc/uid/DTS10003091-CH1-SECTION9.  I'm not trying to do live debugging of the kernel.

Thanks,
Jeff

On Jan 12, 2014, at 12:02 PM, Shantonu Sen wrote:

OS X doesn’t support dropping into the kernel debugger on a single system on panic (like Solaris and perhaps others)



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References: 
 >Mavericks kernel panic debugging (From: Jeff Schindler <email@hidden>)
 >Re: Mavericks kernel panic debugging (From: Rustam Muginov <email@hidden>)
 >Re: Mavericks kernel panic debugging (From: jas <email@hidden>)
 >Re: Mavericks kernel panic debugging (From: Shantonu Sen <email@hidden>)
 >Re: Mavericks kernel panic debugging (From: Jeff Schindler <email@hidden>)
 >Re: Mavericks kernel panic debugging (From: Shantonu Sen <email@hidden>)
 >Re: Mavericks kernel panic debugging (From: Jeff Schindler <email@hidden>)
 >Re: Mavericks kernel panic debugging (From: Shantonu Sen <email@hidden>)

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