Hi, On Thu, Jan 18, 2018 at 01:21:27PM -0500, Ben Gamari wrote:
So, if the stack pointer checking diff to OpenBSD is correct, and if I'm not running into a completely unrelated problem: does ghc and/or the runtime library sometimes move the system stack pointer to newly allocated/mapped memory? If so, where in the code?
As far as I know GHC shouldn't touch x86-64's $rsp at all; we specifically avoid using it for the STG stack to ease FFI.
Thanks for the information.
It would be interesting to know what is touching it. Unfortunately, without a tool like rr this may be hard to find.
I doubt it's easy to get rr ported to OpenBSD, so all I can think of at the moment is ktracing every single invocation of ghc during a build (should be relatively easy by patching the ghc wrapper script) and -- after an abort happended, look at the trace to see wether the current stack had been mmapped at all late during the process. At the moment, I'm busy updating all the haskell libraries and tools offically available as OpenBSD packages, but I hope to get back to debugging/tracing in a few days. Ciao, Kili