How to identify the shared library, whose functions are currently being executed by an executable

Question

An executable file, a.out, loads the shared libraries 1.so, 2.so and 3.so. There is a function func() implemented in each of the three libraries. When func() is invoked, I want to identify, which implementation of func() is executed.

I tried ltrace on the PID of the executable file. It only lists the func() call, but not the shared library.

Any suggestions?

Answer 1

Using systemtap:

probe process("/path/to/1.so").function("func")
{
  printf("%d: 1.so\n", pid());
}       

probe process("/path/to/2.so").function("func")
{
  printf("%d: 2.so\n", pid());
}       

probe process("/path/to/3.so").function("func")
{
  printf("%d: 3.so\n", pid());
}       

Use it with:

sudo -E stap ./func.stap

With linux perf:

sudo perf probe -x /path/to/1.so func
sudo perf probe -x /path/to/2.so func
sudo perf probe -x /path/to/3.so func
sudo perf top -e probe_1:func,probe_2:func,probe3:func