Re: [KLUDGE PATCH] Linux vsyscall DSO support

[Andrew Cagney <cagney@gnu.org>]

Roland, FYI.

Last time this was discussed the observer was identified as the correct 
mechanim for hooking this in.  That's why I'm currently overhauling that 
code.

Andrew

> Perhaps you recall the discussion here some months back about what hook to
> use in Linux targets for the detection of the vsyscall DSO.  The last time
> I asked here about a resolution on how best to do this, I got no feedback.
> I hope we can now jumpstart the effort to find the right way to implement
> this.  To get things rolling again, here is a patch that I am not
> suggesting for inclusion, but does work.  This is a kludge to overload the
> solib hooks with target-specific code.  These solib hooks get called at
> roughly (or perhaps even precisely?) the correct places where the vsyscall
> DSO checks ought to happen.  A reminder, the appropriate places are when
> gdb thinks the address space might be a fresh layout from what it knows,
> i.e. first attach (or any attach?), after exec, and on opening a core file.
> 
> As I said, this code works for me.  (It requires symbol_file_add_from_memory,
> which is in the patch I just re-posted.)  It seems doubtful this is the
> ultimately desireable approach to wedging this code in where needs to be.
> But it's what I've got, and as I said I'm still waiting for more feedback to
> conclude on exactly what the preferred better thing to do is.
> 
>