Hi Martin,

your binary must have an unwind table compiled in, otherwise you don't 
necessary
get a backtrace. Platform binaries normally have that, but if construct 
your own 
toolchain calls, you must have unwind-tables and debug symbols enabled.
If you still have a problem, you can try to get GDB running or use 
libunwind on Android,
but I think it is the lack of unwind tables that causes the issue.

Br,

Zoltan

On Thursday, 19 March 2015 13:35:16 UTC+1, Martin Siegumfeldt wrote:
>
> Hi,
>
> I was wondering if the Lollipop behavior of the tombstones have changed 
> somewhere around Jellybean/Lollipop? With reference to 
> http://www.kandroid.org/online-pdk/guide/debugging_native.html (yes, I 
> know it is quite outdated) the tombstone contains the value of the PC 
> iterating the individual libraries for easy backtrace through the 'stack' 
> script:
>
> I/DEBUG: pid: 373, tid: 401  >>> android.content.providers.pim <<<
> I/DEBUG: signal 11 (SIGSEGV), fault addr 00000000
> I/DEBUG:  r0 ffffffff  r1 00000000  r2 00000454  r3 002136d4
> I/DEBUG:  r4 002136c0  r5 40804810  r6 0022dc70  r7 00000010
> I/DEBUG:  r8 0020a258  r9 00000014  10 6b039074  fp 109ffcf8
> I/DEBUG:  ip 6b039e90  sp 109ffc0c  lr 580239f0  pc 6b0156a0
> I/DEBUG:          #01  pc 6b0156a0  /android/lib/libjamvm.so
> I/DEBUG:          #01  lr 580239f0  /android/lib/libandroid_runtime.so
> I/DEBUG:          #02  pc 6b01481c  /android/lib/libjamvm.so
> I/DEBUG:          #03  pc 6b0148a4  /android/lib/libjamvm.so
> I/DEBUG:          #04  pc 6b00ebc0  /android/lib/libjamvm.so
> I/DEBUG:          #05  pc 6b02166c  /android/lib/libjamvm.so
> I/DEBUG:          #06  pc 6b01657c  /android/lib/libjamvm.so
> I/DEBUG:          #07  pc 6b01481c  /android/lib/libjamvm.so
> I/DEBUG:          #08  pc 6b0148a4  /android/lib/libjamvm.so
>
> I am currently debugging a segfaulting Lollipop based system but do not 
> see the convenient trace from above:
>
> pid: 10195, tid: 10195, name: mediaserver  >>> /system/bin/mediaserver <<<
> signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0
>     eax 00000000  ebx 74582cbc  ecx 74582cbc  edx 44274c7c
>     esi 745840d8  edi 00000000
>     xcs 00000073  xds 0000007b  xes 0000007b  xfs 00000000  xss 0000007b
>     eip 00000000  ebp 745840e0  esp 7ff22acc  flags 00010283
>
> backtrace:
>     #00 pc 00000000  <unknown>
>     #01 pc 0006ffff  <unknown>
>
> stack:
>          7ff22a8c  44274c7c
>          7ff22a90  758031f0  [anon:libc_malloc]
>          7ff22a94  00000000
>          7ff22a98  7745d679  /system/lib/libcutils.so 
> (__android_log_vprint+9)
>          7ff22a9c  74582cbc  /system/lib/mylib.so
>          7ff22aa0  74584080  /system/lib/mylib.so
>          7ff22aa4  00000000
>          7ff22aa8  745840e0  /system/lib/mylib.so
>          7ff22aac  7452f6a6  /system/lib/mylib.so (lib_ilog_print+70)
>          7ff22ab0  00000004
>          7ff22ab4  74554b18  /system/lib/mylib.so
>          7ff22ab8  745548b4  /system/lib/mylib.so
>          7ff22abc  7ff22ad4  [stack]
>          7ff22ac0  00000000
>          7ff22ac4  7452f666  /system/lib/mylib.so (lib_ilog_print+6)
>          7ff22ac8  74508b15  /system/lib/mylib.so 
> (lib_silent_poweron_init+5)
>     #00  7ff22acc  74501735  /system/lib/mylib.so (lib_modules_init+53)
>          7ff22ad0  00000000
>          7ff22ad4  7ff22aef  [stack]
>          7ff22ad8  00000002
>          7ff22adc  758031e0  [anon:libc_malloc]
>          7ff22ae0  00000000
>          7ff22ae4  00000000
>          7ff22ae8  74501709  /system/lib/mylib.so (lib_modules_init+9)
>          7ff22aec  74582cbc  /system/lib/mylib.so
>          7ff22af0  00000040
>          7ff22af4  00000000
>          7ff22af8  7458ba10
>          7ff22afc  744f6b15  /system/lib/mylib.so (lib_set_driver_mode+949)
>          7ff22b00  00000000
>          7ff22b04  7ff22b3c  [stack]
>          7ff22b08  00000040
>          ........  ........
>     #01  745840e8  00000000
>          745840ec  00000000
>          745840f0  00000000
>          745840f4  00000000
>          745840f8  00000000
>          745840fc  00000000
>          74584100  ffffffff
>          74584104  ffffffff
>          74584108  0000ffff
>          7458410c  00000000
>          74584110  00000000
>          74584114  00000000
>          74584118  00000000
>          7458411c  00000000
>          74584120  000b0000
>          74584124  00000b00
>
> As you can see the PC value is not present for the library iteration and I 
> thus have no means for doing the source code line-mapping. The output from 
> the 'stack' tool is as a consequence not very helpful
>
> Stack Trace:
>   RELADDR   FUNCTION  FILE:LINE
>   00000000    <unknown>
>   0006ffff    <unknown>
>
> Stack Data:
>   ADDR      VALUE     FUNCTION                   FILE:LINE
>   7ff22a8c  44274c7c
>   7ff22a90  758031f0  <unknown>                  [anon:libc_malloc]
>   7ff22a94  00000000
>   7ff22a98  7745d679  __android_log_vprint+9     /system/lib/libcutils.so
>   7ff22a9c  74582cbc  <unknown>                  /system/lib/mylib.so
>   7ff22aa0  74584080  <unknown>                  /system/lib/mylib.so
>   7ff22aa4  00000000
>   7ff22aa8  745840e0  <unknown>                  /system/lib/mylib.so
>   7ff22aac  7452f6a6  lib_ilog_print+70          /system/lib/mylib.so
>   7ff22ab0  00000004
>   7ff22ab4  74554b18  <unknown>                  /system/lib/mylib.so
>   7ff22ab8  745548b4  <unknown>                  /system/lib/mylib.so
>   7ff22abc  7ff22ad4                             [stack]
>   7ff22ac0  00000000
>   7ff22ac4  7452f666  lib_ilog_print+6           /system/lib/mylib.so
>   7ff22ac8  74508b15  lib_silent_poweron_init+5  /system/lib/mylib.so
>   7ff22acc  74501735  lib_modules_init+53        /system/lib/mylib.so
>   7ff22ad0  00000000
>   7ff22ad4  7ff22aef                             [stack]
>   7ff22ad8  00000002
>   7ff22adc  758031e0  <unknown>                  [anon:libc_malloc]
>   7ff22ae0  00000000
>   7ff22ae4  00000000
>   7ff22ae8  74501709  lib_modules_init+9         /system/lib/mylib.so
>   7ff22aec  74582cbc  <unknown>                  /system/lib/mylib.so
>   7ff22af0  00000040
>   7ff22af4  00000000
>   7ff22af8  7458ba10
>   7ff22afc  744f6b15  lib_set_driver_mode+949    /system/lib/mylib.so
>   7ff22b00  00000000
>   7ff22b04  7ff22b3c                             [stack]
>   7ff22b08  00000040
>
>
> There are additional threads running of the particular process, and it is 
> not clear to me which one causing the segfault. 
>
> Has the tombstone generating changed in 'recent' Android versions or is 
> something broken in my toolchain?
>
> Thanks,
> Martin
>
>

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