Re: Run system tap with a user defined function

[fche@redhat.com (Frank Ch. Eigler)]

Yeshpal Jain via Systemtap <systemtap@sourceware.org> writes:

> function __read_phase:long(phase:long) %{ /* pure */
>         struct phase *phase_s = (struct phase *)((long)STAP_ARG_phase);
>         int phase_st = phase->p_state;
>         STAP_RETURN(phase_st);
> %} /* <-- function body */

Keeping in mind that, by default, you're using the linux kernel runtime,
this means that any declarations your embedded-C code needs need to be
included manually (like Bryn said), but in such a way that a
kernel-oriented module build can use it.  So no #include <stdio.h>,
which is a userspace header.

You might find it simpler to code this up as pure script code:


   { ... 
     print ("%s",  @cast($fom, "phase", "<mylibrary/phase.h>")->p_state;
     ...
   }

In this case, @cast() takes a -userpace- header file name, and should
generate enough debuginfo out of it to let the ->p_state part resolve
naturally.  As a bonus, no -g guru mode required.

- FChE