On Tue, Jun 23, 2020 at 05:38:55PM +0200, Joerg Roedel wrote: > On Tue, Jun 23, 2020 at 05:23:26PM +0200, Peter Zijlstra wrote: > > Reliability of that depends on the unwinder, I wouldn't want the guess > > uwinder to OOPS me by accident. > > It doesn't use the full unwinder, it just assumes that there is a > pt_regs struct at the top of every kernel stack and walks through them > until SP points to a user-space stack. > > As long as the assumption that there is a pt_regs struct on top of every > stack holds, this should be safe. The assumption might be wrong when an > exception happens during SYSCALL/SYSENTER entry, when the return frame > is not written by hardware. The IRQ and SoftIRQ stacks don't have that I think. Only the task and exception stacks.
