On Thu, 3 Jul 2025 18:21:10 +0200 Jens Remus <jremus@xxxxxxxxxxxxx> wrote: > >> /* stack going in wrong direction? */ > >> if (sp <= state->sp - topmost) > >> goto done; > > > > How do you calculate "topmost" then? > > > > Is it another field you add to "state"? > > Correct. It is a boolean set to true in unwind_user_start() and set to > false in unwind_user_next() when updating the state. So it's subtracting 1 or zero? So that the topmost can be equal. Well, that would need a bit of commenting. > > I assume most architectures need above change, as their SP at function > entry should be equal to the SP at call site (unlike x86-64 due to CALL). > > s390 also needs this information to allow restoring of FP/RA saved in > other registers (instead of on the stack) only for the topmost frame. > For any other frame arbitrary register contents would not be available, > as user unwind only unwinds SP, FP, and RA. > > I would post my s390 sframe support patches as RFC once you have > provided a merged sframe branch as discussed in: > https://lore.kernel.org/all/20250702124737.565934b5@xxxxxxxxxxxxxxxxx/ I did have a merge branch on my repo. But I was hoping to see your code so that I can add this to this patch before having to post again. But now I'm posting without this change, as I don't want to screw it up. I think I know what it it looks like, but it would be better to see what you did to make sure what I envision is correct. Oh well. I'll post v13 without it. -- Steve
