From: Peter Zijlstra <peterz@infradead.org>
To: Kaixu Xia <xiakaixu@huawei.com>
Cc: ast@plumgrid.com, davem@davemloft.net, acme@kernel.org,
mingo@redhat.com, masami.hiramatsu.pt@hitachi.com,
jolsa@kernel.org, wangnan0@huawei.com,
linux-kernel@vger.kernel.org, pi3orama@163.com,
hekuang@huawei.com
Subject: Re: [PATCH v3 2/3] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter
Date: Mon, 3 Aug 2015 11:34:37 +0200 [thread overview]
Message-ID: <20150803093437.GE19282@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1437644562-84431-3-git-send-email-xiakaixu@huawei.com>
On Thu, Jul 23, 2015 at 09:42:41AM +0000, Kaixu Xia wrote:
> +static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
> +{
> + struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
> + struct bpf_array *array = container_of(map, struct bpf_array, map);
> + struct perf_event *event;
> +
> + if (index >= array->map.max_entries)
> + return -E2BIG;
> +
> + event = array->events[index];
> + if (!event)
> + return -EBADF;
> +
> + if (event->state != PERF_EVENT_STATE_ACTIVE)
> + return -ENOENT;
> +
> + if (event->oncpu != raw_smp_processor_id() &&
> + event->ctx->task != current)
> + return -EINVAL;
> +
> + if (event->attr.inherit)
> + return -EINVAL;
> +
> + __perf_event_read(event);
> +
> + return perf_event_count(event);
> +}
Please no poking of event internal state outside of perf code.
next prev parent reply other threads:[~2015-08-03 9:34 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-23 9:42 [PATCH v3 0/3] bpf: Introduce the new ability of eBPF programs to access hardware PMU counter Kaixu Xia
2015-07-23 9:42 ` [PATCH v3 1/3] bpf: Add new bpf map type to store the pointer to struct perf_event Kaixu Xia
2015-07-23 22:54 ` Alexei Starovoitov
2015-07-24 2:22 ` xiakaixu
2015-07-24 2:26 ` Alexei Starovoitov
2015-08-03 9:38 ` Peter Zijlstra
2015-07-23 9:42 ` [PATCH v3 2/3] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter Kaixu Xia
2015-07-23 22:56 ` Alexei Starovoitov
2015-07-24 1:57 ` xiakaixu
2015-08-03 9:34 ` Peter Zijlstra [this message]
2015-08-03 10:32 ` xiakaixu
2015-07-23 9:42 ` [PATCH v3 3/3] samples/bpf: example of get selected PMU counter value Kaixu Xia
2015-07-23 22:59 ` Alexei Starovoitov
2015-07-24 1:54 ` xiakaixu
2015-07-24 2:23 ` Alexei Starovoitov
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