Stepping over longjmp presumably broken for glibc

[Eli Zaretskii]

> Date: Thu, 22 Dec 2005 16:17:34 -0500
> From: Daniel Jacobowitz <drow@false.org>
> Cc: libc-alpha@sourceware.org
> 
> Current versions of glibc for many platforms xor the saved PC with a
> randomized canary, so setting a breakpoint at that "address" isn't
> going to work especially well.

How does glibc restore the correct address when you call longjmp?  Do
they save the canary in some place, or something?