Re: [patch 4/8] x86/entry: Move irq tracing on syscall entry to C-code

Thomas Gleixner
2020-03-01T10:16:48Z

Steven Rostedt <rostedt@goodmis.org> writes:

> On Sat, 29 Feb 2020 11:25:24 -0800
> Andy Lutomirski <luto@amacapital.net> wrote:
>
>> > While the tracer itself seems to handle this correctly, what about
>> > things like BPF programs which can be attached to tracepoints and
>> > function trace entries?
>>
>> I think that everything using the tracing code, including BPF, should
>> either do its own rcuidle stuff or explicitly not execute if we’re
>> not in CONTEXT_KERNEL. That is, we probably need to patch BPF.
>
> That's basically the route we are taking.

Ok, but for the time being anything before/after CONTEXT_KERNEL is unsafe
except trace_hardirq_off/on() as those trace functions do not allow to
attach anything AFAICT.

Thanks,

tglx