Re: Suggestion: backtrace stop guard for threads callstacks

[Daniel Jacobowitz <drow@false.org>]

On Wed, Mar 01, 2006 at 05:29:43PM -0800, Joel Brobecker wrote:
> It's a little bit less simple for the general case for C, C++ and other
> languages, but I suggest we implement something similar. How about we
> add some code that recognizes some of the thread entry-points? For
> the GNU/Linux NPTL for instance, we could recognize clone() or perhaps
> _start_thread? We could make the check as stringent as we like, for
> instance not only check the funtion name, but also the object name,
> to make sure we're inside the pthread library.

FYI, this is discussed here about five times a year in one form or
another.  For systems we control, the correct solution is not this at
all, but to add unwinding information or suitable prologues that
indicate the end of the stack.  Almost every architecture has a
suitable sequence, and we have a recently-decided-upon DWARF convention
to represent it also.

Whatever platform you're looking at, does the beginning of
_thread_start make sufficiently clear that we're at the end of the
stack?  If not, perhaps you should register an appropriate unwinder to
notice it and stop.

-- 
Daniel Jacobowitz
CodeSourcery