Re: [patch] Re: longjmp handling vs. glibc LD_POINTER_GUARD problems

Daniel Jacobowitz
2008-05-21T22:16:11Z

On Wed, May 21, 2008 at 11:01:25PM +0100, Pedro Alves wrote:
> Hmmm, I got blocked getting that to work. It always stops stepping
> before getting to the other side. It looks like going out of
> longjmp, the frame id of the longjmp's caller starts
> being computed differently, or badly...

This is the same problem as software watchpoints... I just don't think
we're going to be able to get it to work. I certainly had to do
horrible things on powerpc-linux when I wanted to be able to backtrace
from epilogues without a symbol table.

Which frame IDs are we comparing here? I think we can assume that
longjmp is not going to change stacks until it's about to return,
although the return might be on a different stack entirely.

I suspect we'll be prone to stopping in the last instruction or two of
longjmp, instead of returning the compiler.

--
Daniel Jacobowitz
CodeSourcery