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Re: [PATCH v2 net-next 4/6] perf, bpf: add perf events core support for BPF_PROG_TYPE_PERF_EVENT programs

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [PATCH v2 net-next 4/6] perf, bpf: add perf events core support for BPF_PROG_TYPE_PERF_EVENT programs
Date 2016-09-01 10:20 +0200
Message-ID <scvo5-6SP-13@gated-at.bofh.it> (permalink)
References <sclI5-7NG-3@gated-at.bofh.it> <sclI5-7NG-7@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Wed, Aug 31, 2016 at 02:50:41PM -0700, Alexei Starovoitov wrote:
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index 97bfe62f30d7..dcaaaf3ec8e6 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -679,6 +679,8 @@ struct perf_event {
>  	u64				(*clock)(void);
>  	perf_overflow_handler_t		overflow_handler;
>  	void				*overflow_handler_context;

> +	perf_overflow_handler_t		orig_overflow_handler;
> +	struct bpf_prog			*prog;

Should we put that under CONFIG_BPF_SYSCALL too?

> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 3cfabdf7b942..305433ab2447 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c

> @@ -7637,11 +7637,75 @@ static void perf_event_free_filter(struct perf_event *event)
>  	ftrace_profile_free_filter(event);
>  }
>  
> +static void bpf_overflow_handler(struct perf_event *event,
> +				 struct perf_sample_data *data,
> +				 struct pt_regs *regs)
> +{
> +	struct bpf_perf_event_data_kern ctx = {
> +		.data = data,
> +		.regs = regs,
> +	};
> +	int ret = 0;
> +
> +#ifdef CONFIG_BPF_SYSCALL
> +	preempt_disable();
> +	if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1))
> +		goto out;
> +	rcu_read_lock();
> +	ret = BPF_PROG_RUN(event->prog, (void *)&ctx);
> +	rcu_read_unlock();
> + out:

Please, no leading space before labels. Use something like:

[diff "default"]
        xfuncname = "^[[:alpha:]$_].*[^:]$"

In your .gitconfig if you want to keep diff output 'sane'.

> +	__this_cpu_dec(bpf_prog_active);
> +	preempt_enable();
> +#endif
> +	if (!ret)
> +		return;
> +
> +	event->orig_overflow_handler(event, data, regs);
> +}

Other than that, ACK.

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Thread

[PATCH v2 net-next 4/6] perf, bpf: add perf events core support for BPF_PROG_TYPE_PERF_EVENT programs Alexei Starovoitov <ast@fb.com> - 2016-09-01 00:00 +0200
  Re: [PATCH v2 net-next 4/6] perf, bpf: add perf events core support  for BPF_PROG_TYPE_PERF_EVENT programs Peter Zijlstra <peterz@infradead.org> - 2016-09-01 10:20 +0200
    Re: [PATCH v2 net-next 4/6] perf, bpf: add perf events core support  for BPF_PROG_TYPE_PERF_EVENT programs Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2016-09-01 18:00 +0200
      Re: [PATCH v2 net-next 4/6] perf, bpf: add perf events core support  for BPF_PROG_TYPE_PERF_EVENT programs Peter Zijlstra <peterz@infradead.org> - 2016-09-01 18:40 +0200

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