Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <CACT4Y+YPrXGw+AtESxAgPyZ84TYkNZdP0xpocX2jwVAbZD=-XQ@mail.gmail.com>
 <20201112103125.GV2628@hirez.programming.kicks-ass.net> <CACT4Y+ayRHua-6UyRwSM3=_oi+NkXbaO3-zZ1mpDmWonbybkeA@mail.gmail.com>
 <CACT4Y+bW1gpv8bz0vswaVUt-OB07oJ3NBeTi+vchAe8TTWK+mg@mail.gmail.com> <CACT4Y+ZsKXfAxrzJGQc5mJ+QiP5sAw7zKWtciS+07qZzSf33mw@mail.gmail.com>
In-Reply-To: <CACT4Y+ZsKXfAxrzJGQc5mJ+QiP5sAw7zKWtciS+07qZzSf33mw@mail.gmail.com>
From:   Namhyung Kim <namhyung@kernel.org>
Date:   Wed, 3 Feb 2021 14:38:34 +0900
Message-ID: <CAM9d7ci4GqApJoG5B2ise2R20Eu7yz1zFxkA+wM-LoCDRCdnbw@mail.gmail.com>
Subject: Re: Process-wide watchpoints
To:     Dmitry Vyukov <dvyukov@google.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>, Will Deacon <will@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Matt Morehouse <mascasa@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hello,

On Sun, Jan 31, 2021 at 7:28 PM Dmitry Vyukov <dvyukov@google.com> wrote:
> Not directly related to the above question, but related to my use case.
> Could we extend bpf_perf_event_data with some more data re breakpoint events?
>
> struct bpf_perf_event_data {
>     bpf_user_pt_regs_t regs;
>     __u64 sample_period;
>     __u64 addr;
> };
>
> Ideally, I would like to have an actual access address, size and
> read/write type (may not match bp addr/size). Is that info easily
> available at the point of bpf hook call?
> Or, if that's not available at least breakpoint bp_type/bp_size.
>
> Is it correct that we can materialize in bpf_perf_event_data anything
> that's available in bpf_perf_event_data_kern (if it makes sense in the
> public interface of course)?
>
> struct bpf_perf_event_data_kern {
>     bpf_user_pt_regs_t *regs;
>     struct perf_sample_data *data;
>     struct perf_event *event;
> };
>
> Unfortunately I don't see perf_event_attr.bp_type/bp_size
> stored/accessible anywhere in bpf_perf_event_data_kern. What would be
> the right way to expose them in bpf_perf_event_data?

I think you can access it via event->attr.bp_type/size in the struct
bpf_perf_event_data_kern.

Thanks,
Namhyung