With the arrival of non-[uk]retprobe mechanisms to trap return events (e.g., tp_syscall.*.return), the traditional @entry(expression) trick is no longer directly workable.  This is because there is no mechanically-obvious entry probe to collect the expression, and @entry($var) may need $var that are not available at all in that form.

So we need to generalize this a bit.

One way is to introduce some macros that explicitly implement the @entry() machinations behind the scenes:

- one macro to 'probe entry point & save variables'
- and one macro to 'probe exit point & expose saved variables'

used something like

probe syscall.* { @save(myargstr,argstr) }

probe syscall.*.return { 
    @restore(myargstr)
    log(myargstr)
}

which would expand to code that manages a myargstr global array, tid()-indexed.