In order to do finer-grain-than-function profiling, it's desirable
to map a random PC to something more precise than [u]symdata() gives.

It may be practical to upload subsets/variants of the .debug_line data,
in order to enable a [u]symfileline() function that would produce a
file:line# string.  With that, this ditty should give a nice
line-by-line profile, as in opannotate --assembly.

global prof
probe timer.profile {
  prof [(user_mode() ? usymfileline(uaddr()) : symfileline(addr() /*?*/)] <<< 1
}

probe end {
  foreach (fileline+ in prof) {
     printf("%20s %6d\n", fileline, @count(prof[fileline]))
  }
}