From: Alexei Starovoitov <ast@plumgrid•com>
To: Peter Zijlstra <peterz@infradead•org>, Kaixu Xia <xiakaixu@huawei•com>
Cc: davem@davemloft•net, acme@kernel•org, mingo@redhat•com,
masami.hiramatsu.pt@hitachi•com, jolsa@kernel•org,
daniel@iogearbox•net, wangnan0@huawei•com,
linux-kernel@vger•kernel.org, pi3orama@163•com,
hekuang@huawei•com, netdev@vger•kernel.org
Subject: Re: [PATCH v6 3/4] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter
Date: Wed, 5 Aug 2015 08:59:36 -0700 [thread overview]
Message-ID: <55C232E8.50201@plumgrid.com> (raw)
In-Reply-To: <20150805100425.GZ25159@twins.programming.kicks-ass.net>
On 8/5/15 3:04 AM, Peter Zijlstra wrote:
>> >+ __perf_event_read(event);
>> >+ return perf_event_count(event);
>> >+}
> Also, you probably want a WARN_ON(in_nmi()) there, this function is
> _NOT_ NMI safe.
we check that very early on:
unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx)
{
unsigned int ret;
if (in_nmi()) /* not supported yet */
return 1;
...
next prev parent reply other threads:[~2015-08-05 15:59 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-04 8:58 [PATCH v6 0/4] bpf: Introduce the new ability of eBPF programs to access hardware PMU counter Kaixu Xia
2015-08-04 8:58 ` [PATCH v6 1/4] bpf: Make the bpf_prog_array_map more generic Kaixu Xia
2015-08-04 8:58 ` [PATCH v6 2/4] bpf: Add new bpf map type to store the pointer to struct perf_event Kaixu Xia
2015-08-04 17:43 ` Alexei Starovoitov
2015-08-05 9:41 ` Peter Zijlstra
2015-08-05 9:39 ` Peter Zijlstra
2015-08-05 9:43 ` Peter Zijlstra
2015-08-04 8:58 ` [PATCH v6 3/4] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter Kaixu Xia
2015-08-04 17:55 ` Alexei Starovoitov
2015-08-05 2:09 ` xiakaixu
2015-08-05 10:04 ` Peter Zijlstra
2015-08-05 10:15 ` Peter Zijlstra
2015-08-05 16:00 ` Alexei Starovoitov
2015-08-05 10:31 ` xiakaixu
2015-08-05 13:53 ` Peter Zijlstra
2015-08-05 13:59 ` Peter Zijlstra
2015-08-05 16:08 ` Alexei Starovoitov
2015-08-05 16:21 ` Peter Zijlstra
2015-08-06 2:49 ` xiakaixu
2015-08-05 15:59 ` Alexei Starovoitov [this message]
2015-08-04 8:58 ` [PATCH v6 4/4] samples/bpf: example of get selected PMU counter value Kaixu Xia
2015-08-05 10:06 ` [PATCH v6 0/4] bpf: Introduce the new ability of eBPF programs to access hardware PMU counter Peter Zijlstra
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