From: Jiri Olsa <jolsa@redhat.com>
To: Song Liu <songliubraving@fb.com>
Cc: Networking <netdev@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
"ast@kernel.org" <ast@kernel.org>,
"daniel@iogearbox.net" <daniel@iogearbox.net>,
Kernel Team <Kernel-team@fb.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"acme@redhat.com" <acme@redhat.com>,
"jolsa@kernel.org" <jolsa@kernel.org>,
"namhyung@kernel.org" <namhyung@kernel.org>
Subject: Re: [PATCH v5 perf,bpf 07/15] perf, bpf: save bpf_prog_info information as headers to perf.data
Date: Mon, 4 Mar 2019 21:23:23 +0100 [thread overview]
Message-ID: <20190304202323.GA2563@krava> (raw)
In-Reply-To: <CE031049-FB10-4BB5-BCA1-EA48C5BF882B@fb.com>
On Mon, Mar 04, 2019 at 07:36:14PM +0000, Song Liu wrote:
>
>
> > On Mar 4, 2019, at 5:52 AM, Jiri Olsa <jolsa@redhat.com> wrote:
> >
> > On Wed, Feb 27, 2019 at 09:06:35PM -0800, Song Liu wrote:
> >
> > SNIP
> >
> >> +static int process_bpf_prog_info(struct feat_fd *ff,
> >> + void *data __maybe_unused)
> >> +{
> >> + struct bpf_prog_info_linear *info_linear;
> >> + struct bpf_prog_info_node *info_node;
> >> + struct perf_env *env = &ff->ph->env;
> >> + u32 count, i;
> >> + int err = -1;
> >> +
> >> + if (do_read_u32(ff, &count))
> >> + return -1;
> >> +
> >> + down_write(&env->bpf_progs.lock);
> >> +
> >> + for (i = 0; i < count; ++i) {
> >> + u32 info_len, data_len;
> >> +
> >> + info_linear = NULL;
> >> + info_node = NULL;
> >> + if (do_read_u32(ff, &info_len))
> >> + goto out;
> >> + if (do_read_u32(ff, &data_len))
> >> + goto out;
> >> +
> >> + if (info_len > sizeof(struct bpf_prog_info)) {
> >> + pr_warning("detected invalid bpf_prog_info\n");
> >> + goto out;
> >> + }
> >> +
> >> + info_linear = malloc(sizeof(struct bpf_prog_info_linear) +
> >> + data_len);
> >> + if (!info_linear)
> >> + goto out;
> >> + info_linear->info_len = sizeof(struct bpf_prog_info);
> >> + info_linear->data_len = data_len;
> >> + if (do_read_u64(ff, (u64 *)(&info_linear->arrays)))
> >> + goto out;
> >> + if (__do_read(ff, &info_linear->info, info_len))
> >> + goto out;
> >> + if (info_len < sizeof(struct bpf_prog_info))
> >> + memset(((void *)(&info_linear->info)) + info_len, 0,
> >> + sizeof(struct bpf_prog_info) - info_len);
> >> +
> >> + if (__do_read(ff, info_linear->data, data_len))
> >> + goto out;
> >> +
> >> + /* endian mismatch, drop the info, continue */
> >> + if (ff->ph->needs_swap) {
> >> + free(info_linear);
> >> + continue;
> >> + }
> >
> > so in this case we can check for needs_swap in the begining
> > of the function and bail out without reading all the data
>
> If we bail out, perf-record will fail. If we read all the data
> but ignore them, perf-record will continue without bpf annotation
> support. I think the latter is a better experience with little
> effort here.
i did not mean bail out with error, just return 0, warn and go on
jirka
>
> >
> > also please display soem error message saying we don't support
> > ebpf progs data report over the different endianity
>
> I will add a warning in the next version.
>
> Thanks,
> Song
>
next prev parent reply other threads:[~2019-03-04 20:23 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-28 5:06 [PATCH v5 perf,bpf 00/15] perf annotation of BPF programs Song Liu
2019-02-28 5:06 ` [PATCH v5 perf,bpf 01/15] perf, bpf: consider events with attr.bpf_event as side-band events Song Liu
2019-02-28 5:06 ` [PATCH v5 perf,bpf 02/15] bpf: libbpf: introduce bpf_program__get_prog_info_linear() Song Liu
2019-02-28 5:06 ` [PATCH v5 perf,bpf 03/15] bpf: bpftool: use bpf_program__get_prog_info_linear() in prog.c:do_dump() Song Liu
2019-02-28 5:06 ` [PATCH v5 perf,bpf 04/15] perf, bpf: synthesize bpf events with bpf_program__get_prog_info_linear() Song Liu
2019-02-28 5:06 ` [PATCH v5 perf,bpf 05/15] perf: change prototype of perf_event__synthesize_bpf_events() Song Liu
2019-02-28 5:06 ` [PATCH v5 perf,bpf 06/15] perf, bpf: save bpf_prog_info in a rbtree in perf_env Song Liu
2019-02-28 5:06 ` [PATCH v5 perf,bpf 07/15] perf, bpf: save bpf_prog_info information as headers to perf.data Song Liu
2019-03-04 13:52 ` Jiri Olsa
2019-03-04 19:36 ` Song Liu
2019-03-04 20:23 ` Jiri Olsa [this message]
2019-03-04 20:31 ` Song Liu
2019-03-04 13:52 ` Jiri Olsa
2019-03-04 13:52 ` Jiri Olsa
2019-03-04 19:41 ` Song Liu
2019-03-04 20:37 ` Jiri Olsa
2019-03-04 13:52 ` Jiri Olsa
2019-02-28 5:06 ` [PATCH v5 perf,bpf 08/15] perf, bpf: save btf in a rbtree in perf_env Song Liu
2019-03-04 13:52 ` Jiri Olsa
2019-03-04 19:43 ` Song Liu
2019-03-04 20:31 ` Jiri Olsa
2019-03-04 13:53 ` Jiri Olsa
2019-02-28 5:06 ` [PATCH v5 perf,bpf 09/15] perf, bpf: save btf information as headers to perf.data Song Liu
2019-03-04 13:52 ` Jiri Olsa
2019-02-28 5:06 ` [PATCH v5 perf,bpf 10/15] perf-top: add option --no-bpf-event Song Liu
2019-02-28 5:06 ` [PATCH v5 perf,bpf 11/15] perf: add -lopcodes to feature-libbfd Song Liu
2019-02-28 5:06 ` [PATCH v5 perf,bpf 12/15] perf, bpf: enable annotation of bpf program Song Liu
2019-03-04 13:52 ` Jiri Olsa
2019-03-04 13:53 ` Jiri Olsa
2019-03-04 20:52 ` Song Liu
2019-03-04 13:53 ` Jiri Olsa
2019-03-04 19:45 ` Song Liu
2019-03-04 20:37 ` Jiri Olsa
2019-03-04 20:43 ` Song Liu
2019-02-28 5:06 ` [PATCH v5 perf,bpf 13/15] perf, bpf: process PERF_BPF_EVENT_PROG_LOAD for annotation Song Liu
2019-03-04 13:53 ` Jiri Olsa
2019-02-28 5:06 ` [PATCH v5 perf,bpf 14/15] perf: introduce side band thread Song Liu
2019-02-28 5:06 ` [PATCH v5 perf,bpf 15/15] perf, bpf: save bpf_prog_info and btf of short living bpf programs Song Liu
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