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    SubjectRe: [PATCH 0/8] tracing vs rcu vs nmi
    On Wed, Feb 12, 2020 at 11:01:06AM +0100, Peter Zijlstra wrote:
    > On Wed, Feb 12, 2020 at 10:32:10AM +0100, Peter Zijlstra wrote:
    > > Hi all,
    > >
    > > These here patches are the result of Mathieu and Steve trying to get commit
    > > 865e63b04e9b2 ("tracing: Add back in rcu_irq_enter/exit_irqson() for rcuidle
    > > tracepoints") reverted again.
    > >
    > > One of the things discovered is that tracing MUST NOT happen before nmi_enter()
    > > or after nmi_exit(). I've only fixed x86, but quickly gone through other
    > > architectures and there is definitely more stuff to be fixed (simply grep for
    > > nmi_enter in your arch).
    >
    > For ARM64:
    >
    > - apei_claim_sea()
    > - __sdei_handler()
    > - do_serror()
    > - debug_exception_enter() / do_debug_exception()
    >
    > all look dodgy.

    Hmm, so looks like we need to spinkle some 'notrace' annotations around
    these. Are there are scenarios where you would want NOKPROBE_SYMBOL() but
    *not* 'notrace'? We've already got the former for the debug exception
    handlers and we probably (?) want it for the SDEI stuff too...

    Will

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