On Thu, Jan 21, 2021 at 12:54:52PM -0600, Josh Poimboeuf wrote:

2) The shadow stack idea sounds promising -- how hard would it be to
   make a prototype reliable unwinder?

In theory it doesn't look too hard and I can't see a particular reason
not to try doing this - there's going to be edge cases but hopefully for
reliable stack trace they're all in areas where we would be happy to
just decide the stack isn't reliable anyway, things like nesting which
allocates separate shadow stacks for each nested level for example.
I'll take a look.