如何通过跟踪调试Android本机崩溃？

Question

I got the following trace on Android.

Question 1: What's the meaning of the r0 ... r9 and sl , fp , ip , sp , lr , sl , pc , cpsr . I'm trying to debug acrroding to the fault addr 0xb0 info.

The code snippet like this:

memcpy(mAudioFrameBuffers[write_pos]->data, audioFrame->data, audioFrame->frameSize);

The trace:

12-13 13:33:19.182 I/DEBUG   (19867): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
12-13 13:33:19.183 I/DEBUG   (19867): Build fingerprint: 'motorola/shamu_retcn/shamu_t:5.0.2/LXG22.67-7.1/2:user/release-keys'
12-13 13:33:19.183 I/DEBUG   (19867): Revision: 'p2b0'
12-13 13:33:19.183 I/DEBUG   (19867): ABI: 'arm'
12-13 13:33:19.183 I/DEBUG   (19867): pid: 22064, tid: 22137, name: AsyncTask #1  >>> com.jerikc.mediastreamerdemo <<<
12-13 13:33:19.183 I/DEBUG   (19867): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0xb0
12-13 13:33:19.205 I/DEBUG   (19867):     r0 00000003  r1 a2dc2bb0  r2 00125365  r3 000000b0
12-13 13:33:19.205 I/DEBUG   (19867):     r4 a3507160  r5 a35090e8  r6 a2dc6ddc  r7 a2dc2bb0
12-13 13:33:19.205 I/DEBUG   (19867):     r8 a2dc6ef4  r9 a2dc3ce6  sl d00bff18  fp 148fb9e5
12-13 13:33:19.205 I/DEBUG   (19867):     ip a1303810  sp a1303cd8  lr a2c9d96b  pc a2c9d97a  cpsr 200f0030
12-13 13:33:19.205 I/DEBUG   (19867):
12-13 13:33:19.205 I/DEBUG   (19867): backtrace:
12-13 13:33:19.205 I/DEBUG   (19867):     #00 pc 0001897a  /data/app/com.jerikc.mediastreamerdemo-2/lib/arm/libMediaStreamer.so (AudioFrameBufferPool::push(AudioFrame*)+205)
12-13 13:33:19.205 I/DEBUG   (19867):     #01 pc 0001f5fb  /data/app/com.jerikc.mediastreamerdemo-2/lib/arm/libMediaStreamer.so (AudioStreamer::mixThread()+330)
12-13 13:33:19.205 I/DEBUG   (19867):     #02 pc 0001f777  /data/app/com.jerikc.mediastreamerdemo-2/lib/arm/libMediaStreamer.so
12-13 13:33:19.205 I/DEBUG   (19867):     #03 pc 0001666b  /system/lib/libc.so (__pthread_start(void*)+30)
12-13 13:33:19.205 I/DEBUG   (19867):     #04 pc 00014643  /system/lib/libc.so (__start_thread+6)

Question 2: Is there any efficient debug method?

Answer 1

r0 to r9 as well as sl, fp etc are your registers. It just shows you the values of the registers when your code 'segfaulted'.

If it crashing during the memcpy(), it is very likely that you are accessing out-of-bounds memory (either reading or writing past the boundaries of your buffers)

As for debugging, here's what you could try:

• first of all, make sure your buffers are correctly allocated
• compile with debug info / disabling optimizations and make it crash again. You should be able to see exactly what line caused the crash as well as the values of your variables (particularly audioFrame->frameSize and mAudioFrameBuffers)