linux-kernel - Re: [PATCH net-next 2/3] bpf: introduce bpf_perf_event

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Message-ID: <562902DA.7010908@plumgrid.com>
Date:	Thu, 22 Oct 2015 08:38:02 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Ingo Molnar <mingo@...nel.org>, Wang Nan <wangnan0@...wei.com>,
	He Kuang <hekuang@...wei.com>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 2/3] bpf: introduce bpf_perf_event_output()
 helper

On 10/22/15 6:59 AM, Peter Zijlstra wrote:
>> +	if (unlikely(event->oncpu != smp_processor_id()))
>> >+		return -EOPNOTSUPP;
>> >+
>> >+	perf_sample_data_init(&sample_data, 0, 0);
>> >+	sample_data.raw = &raw;
>> >+	perf_event_output(event, &sample_data, regs);
>> >+	return 0;
>> >+}
> Note that this function also very much requires event to be local.

correct. that's why there is a dynamic check above to prevent buggy
programs causing issues.


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