On Wed, Feb 22, 2017 at 12:51:11PM -0800, H. Peter Anvin wrote: > On 02/22/17 08:45, Josh Poimboeuf wrote: > >> > >> FWIW, it would be really darned nice to not have all those zeroes in a > >> 32-bit stack frame dump. > > > > Yeah, I'll fix that. > > > >> Is not a zero stack frame pointer value an end of stack token? > > > > There's no end of stack "token" per se, though any frame pointer value > > outside the bounds of the stack will terminate the stack trace (and that > > still happened here). > > > > Well, my understanding is that at least gdb and perhaps other unwinders > consider a zero stack frame pointer to be an indicator that the stack > has reached its end. That's why I'm wondering if this is possible in > this case or if it is unlikely because of the value.
I'm not sure I follow your question. The frame pointer was zero, and that did cause the unwinder to stop the stack trace. The warning was because it ended in an unexpected place. > > The warning is because the stack trace didn't make it all the way to the > > "end" location of the stack (right before the syscall pt_regs location). > > The warning is part of the effort to ensure reliable stacks. > > It would be useful to get an understanding why... Agreed... -- Josh
