Messages in this thread | | | Subject | Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling | From | pi3orama <> | Date | Wed, 21 Oct 2015 22:01:46 +0800 |
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发自我的 iPhone
> 在 2015年10月21日,下午9:49,Peter Zijlstra <peterz@infradead.org> 写道: > >> On Wed, Oct 21, 2015 at 09:42:12PM +0800, Wangnan (F) wrote: >> How can an eBPF program access a !local event: >> >> when creating perf event array we don't care which perf event >> is for which CPU, so perf program can access any perf event in >> that array. > > So what is stopping the eBPF thing from calling perf_event_read_local() > on a !local event and triggering a kernel splat?
I can understand the perf_event_read_local() case, but I really can't understand what is stopping us to write to an atomic field belong to a !local perf event. Could you please give a further explanation?
Thank you. >
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