The man page says that you can't call sigaltstack() while you are actually in
the alternate stack.
I have an emulator app that wants to do some special stuff, and it seems to
require nested calls. [1]
So...
Is it enough in this case to simply bypass the "if (on_sig_stack(sp))" check in
do_sigaltstack()?
Chris
1: Here's why I want to do this, if anyone is interested.
case 1: --the segfault handler is set to run on alt stack, and tries to do some
fancy stuff to trace the call chain
--would like to set up alternate stack for SIGSEGV then drop block on that
signal, while still in the handler for the first instance. If we get the second
fault, then we die a bit more messily.
case 2: --emulator software sets up handler for SIGTRAP on alt stack
--some routines then have to run code in software being emulated, but we don't
trust it
--would like to set up alternate stacks for signals, then drop blocks on them
and run code being emulated, while still running the first handler