From: Jiri Olsa <jolsa@redhat.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: "Jiri Olsa" <jolsa@kernel.org>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
"Andrii Nakryiko" <andriin@fb.com>, "Yonghong Song" <yhs@fb.com>,
"Martin KaFai Lau" <kafai@fb.com>,
"Jakub Kicinski" <jakub.kicinski@netronome.com>,
"David Miller" <davem@redhat.com>,
"Björn Töpel" <bjorn.topel@intel.com>,
"John Fastabend" <john.fastabend@gmail.com>
Subject: Re: [PATCH 2/6] bpf: Add bpf_perf_event_output_kfunc
Date: Wed, 22 Jan 2020 08:51:24 +0100 [thread overview]
Message-ID: <20200122075124.GD801240@krava> (raw)
In-Reply-To: <20200122000322.ogarpgwv3xut75m3@ast-mbp.dhcp.thefacebook.com>
On Tue, Jan 21, 2020 at 04:03:23PM -0800, Alexei Starovoitov wrote:
> On Tue, Jan 21, 2020 at 01:05:08PM +0100, Jiri Olsa wrote:
> > Adding support to use perf_event_output in
> > BPF_TRACE_FENTRY/BPF_TRACE_FEXIT programs.
> >
> > Using nesting regs array from raw tracepoint helpers.
> >
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> > kernel/trace/bpf_trace.c | 41 ++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 41 insertions(+)
> >
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index 19e793aa441a..6a18e2ae6e30 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -1172,6 +1172,43 @@ raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> > }
> > }
> >
> > +BPF_CALL_5(bpf_perf_event_output_kfunc, void *, ctx, struct bpf_map *, map,
> > + u64, flags, void *, data, u64, size)
> > +{
> > + struct pt_regs *regs = get_bpf_raw_tp_regs();
> > + int ret;
> > +
> > + if (IS_ERR(regs))
> > + return PTR_ERR(regs);
> > +
> > + perf_fetch_caller_regs(regs);
> > + ret = ____bpf_perf_event_output(regs, map, flags, data, size);
> > + put_bpf_raw_tp_regs();
> > + return ret;
> > +}
>
> I'm not sure why copy paste bpf_perf_event_output_raw_tp() into new function.
>
> > @@ -1181,6 +1218,10 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> > return &bpf_skb_output_proto;
> > #endif
> > default:
> > + if (prog->expected_attach_type == BPF_TRACE_FENTRY ||
> > + prog->expected_attach_type == BPF_TRACE_FEXIT)
> > + return kfunc_prog_func_proto(func_id, prog);
> > +
> > return raw_tp_prog_func_proto(func_id, prog);
>
> Are you saying bpf_perf_event_output_raw_tp() for some reason
> didn't work for fentry/fexit?
> But above is exact copy-paste and it somehow worked?
>
> Ditto for patches 3,4.
ugh right.. did not realize that after switching to the rawtp
regs nest arrays it's identical and we don't need that
jirka
next prev parent reply other threads:[~2020-01-22 7:51 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-21 12:05 [PATCHv3 0/6] bpf: Add trampoline helpers Jiri Olsa
2020-01-21 12:05 ` [PATCH 1/6] bpf: Allow ctx access for pointers to scalar Jiri Olsa
2020-01-22 1:51 ` Alexei Starovoitov
2020-01-22 2:33 ` Yonghong Song
2020-01-22 9:13 ` Jiri Olsa
2020-01-22 16:09 ` Alexei Starovoitov
2020-01-22 21:18 ` Jiri Olsa
2020-01-23 1:16 ` Alexei Starovoitov
2020-01-21 12:05 ` [PATCH 2/6] bpf: Add bpf_perf_event_output_kfunc Jiri Olsa
2020-01-22 0:03 ` Alexei Starovoitov
2020-01-22 7:51 ` Jiri Olsa [this message]
2020-01-21 12:05 ` [PATCH 3/6] bpf: Add bpf_get_stackid_kfunc Jiri Olsa
2020-01-21 12:05 ` [PATCH 4/6] bpf: Add bpf_get_stack_kfunc Jiri Olsa
2020-01-21 12:05 ` [PATCH 5/6] bpf: Allow to resolve bpf trampoline and dispatcher in unwind Jiri Olsa
2020-01-21 12:05 ` [PATCH 6/6] selftest/bpf: Add test for allowed trampolines count Jiri Olsa
2020-01-22 0:10 ` Alexei Starovoitov
2020-01-22 7:47 ` Jiri Olsa
-- strict thread matches above, loose matches on Subject: below --
2020-01-18 13:49 [PATCHv2 0/6] bpf: Add trampoline helpers Jiri Olsa
2020-01-18 13:49 ` [PATCH 2/6] bpf: Add bpf_perf_event_output_kfunc Jiri Olsa
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