On Wed, May 26, 2021 at 04:49:17PM -0500, madvenka@xxxxxxxxxxxxxxxxxxx wrote: > The unwinder should check if the return PC falls in any function that > is considered unreliable from an unwinding perspective. If it does, > mark the stack trace unreliable. Reviwed-by: Mark Brown <broonie@xxxxxxxxxx> However it'd be good for someone else to double check this as it's entirely possible that I've missed some case here. > + * Some special cases covered by sym_code_functions[] deserve a mention here: > + * - All EL1 interrupt and exception stack traces will be considered > + * unreliable. This is the correct behavior as interrupts and exceptions > + * can happen on any instruction including ones in the frame pointer > + * prolog and epilog. Unless stack metadata is available so the unwinder > + * can unwind through these special cases, such stack traces will be > + * considered unreliable. > + * If you're respinning this it's probably also worth noting that we only ever perform reliable stack trace on either blocked tasks or the current task which should if my reasoning is correct mean that the fact that the exclusions here mean that we avoid having to worry about so many race conditions when entering and leaving functions. If we got preempted at the wrong moment for one of them then we should observe the preemption and mark the trace as unreliable due to that which means that any confusion the race causes is a non-issue.
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