> Basically i have my own malloc, free and load that using LD_PRELOAD before i profile
> the app. I wanted to add stack trace for each alloc/free. I send the LR return address
> from each stack frame to a host where i will do the symbol mapping and make it in
> human readable format.
>
> The first part works fine but when i link with libunwind, the app crashes after sending
> some 20K entries. I tried a simple application that does malloc and free with default gcc
> options and it works fine. This app is compiled with O3 flags for some libraries and
> Os flag for some. basically it is a big beasty app. Here are the details
You don't mention where the sending stacks to other machine comes in your
workflow and exact information about the crash causes.
Here is the snip from the core file and from the logs, it is at the start of the app itself. None of these address fall within the application address map and these must from the shared libraries - either libc, c++, pthread etc?
Program terminated with signal 11, Segmentation fault.
#0 0x4055bca4 in ?? ()
Thread 2 (Thread 1134):
#0 0x400c7ba4 in ?? ()
No symbol table info available.
#1 0x400c7b34 in ?? ()
No symbol table info available.
#2 0x400c7b34 in ?? ()
No symbol table info available.
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
Thread 1 (Thread 1135):
#0 0x4055bca4 in ?? ()
No symbol table info available.
#1 0x4055c1a0 in ?? ()
No symbol table info available.
#2 0x4055c1a0 in ?? ()
No symbol table info available.
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
(gdb
Even if i don't call any of the unwind apis, it crashes exactly at this point with similar core. So this issue is not happening when we are unwinding. But something when we link with libunwind is causing the the crash.
I wrote a small C program with multiple mallocs and free and i can get the stack trace as intended. Not sure if this is anything to do with mix and match of c, c++ code.
Is it something to do with link order or do i need to explicitly specify the unwind method. I found "Gtests-nomalloc.c" inside "tests" dir and according to Ken - it passes.
Any pointers? Also i am thinking of linking libunwind with my library as static instead of shared but i could not get this successful. Do i need to rebuild libunwind with any specific option?
If we have to use this method of unwinding UNW_ARM_UNWIND_METHOD=4 should we set it while compiling my library?