On Fri, 19 Apr 2019, Peter Zijlstra wrote: > On Thu, Apr 18, 2019 at 10:41:47AM +0200, Thomas Gleixner wrote: > > > +typedef bool (*stack_trace_consume_fn)(void *cookie, unsigned long addr, > > + bool reliable); > > > +void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, > > + struct task_struct *task, struct pt_regs *regs); > > +int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, void *cookie, > > + struct task_struct *task); > > This bugs me a little; ideally the _reliable() thing would not exists. > > Thomas said that the existing __save_stack_trace_reliable() is different > enough for the unification to be non-trivial, but maybe Josh can help > out? > > >From what I can see the biggest significant differences are: > > - it looks at the regs sets on the stack and for FP bails early > - bails for khreads and idle (after it does all the hard work!?!) > > The first (FP checking for exceptions) should probably be reflected in > consume_fn(.reliable) anyway -- although that would mean a lot of extra > '?' entries where there are none today. > > And the second (KTHREAD/IDLE) is something that the generic code can > easily do before calling into the arch unwinder. And looking at the powerpc version of it, that has even more interesting extra checks in that function. Thanks, tglx
