linux-kernel - Re: [PATCH 29/35] perf intel-pt: Add some more logging to intel_pt_walk_next

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Message-ID: <CAP-5=fXA56PMT7X4GprdM49L26XD+LP97QOiiQOHpFCL-He+1w@mail.gmail.com>
Date:   Tue, 19 Jul 2022 18:13:10 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Subject: Re: [PATCH 29/35] perf intel-pt: Add some more logging to intel_pt_walk_next_insn()

On Mon, Jul 11, 2022 at 2:33 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> To aid debugging, add some more logging to intel_pt_walk_next_insn().
>
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>

Acked-by: Ian Rogers <irogers@...gle.com>

Thanks,
Ian

> ---
>  tools/perf/util/intel-pt.c | 25 ++++++++++++++++++++-----
>  1 file changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> index 014f9f73cc49..a8798b5bb311 100644
> --- a/tools/perf/util/intel-pt.c
> +++ b/tools/perf/util/intel-pt.c
> @@ -758,27 +758,38 @@ static int intel_pt_walk_next_insn(struct intel_pt_insn *intel_pt_insn,
>
>         if (nr) {
>                 if ((!symbol_conf.guest_code && cpumode != PERF_RECORD_MISC_GUEST_KERNEL) ||
> -                   intel_pt_get_guest(ptq))
> +                   intel_pt_get_guest(ptq)) {
> +                       intel_pt_log("ERROR: no guest machine\n");
>                         return -EINVAL;
> +               }
>                 machine = ptq->guest_machine;
>                 thread = ptq->guest_thread;
>                 if (!thread) {
> -                       if (cpumode != PERF_RECORD_MISC_GUEST_KERNEL)
> +                       if (cpumode != PERF_RECORD_MISC_GUEST_KERNEL) {
> +                               intel_pt_log("ERROR: no guest thread\n");
>                                 return -EINVAL;
> +                       }
>                         thread = ptq->unknown_guest_thread;
>                 }
>         } else {
>                 thread = ptq->thread;
>                 if (!thread) {
> -                       if (cpumode != PERF_RECORD_MISC_KERNEL)
> +                       if (cpumode != PERF_RECORD_MISC_KERNEL) {
> +                               intel_pt_log("ERROR: no thread\n");
>                                 return -EINVAL;
> +                       }
>                         thread = ptq->pt->unknown_thread;
>                 }
>         }
>
>         while (1) {
> -               if (!thread__find_map(thread, cpumode, *ip, &al) || !al.map->dso)
> +               if (!thread__find_map(thread, cpumode, *ip, &al) || !al.map->dso) {
> +                       if (al.map)
> +                               intel_pt_log("ERROR: thread has no dso for %#" PRIx64 "\n", *ip);
> +                       else
> +                               intel_pt_log("ERROR: thread has no map for %#" PRIx64 "\n", *ip);
>                         return -EINVAL;
> +               }
>
>                 if (al.map->dso->data.status == DSO_DATA_STATUS_ERROR &&
>                     dso__data_status_seen(al.map->dso,
> @@ -819,8 +830,12 @@ static int intel_pt_walk_next_insn(struct intel_pt_insn *intel_pt_insn,
>                         len = dso__data_read_offset(al.map->dso, machine,
>                                                     offset, buf,
>                                                     INTEL_PT_INSN_BUF_SZ);
> -                       if (len <= 0)
> +                       if (len <= 0) {
> +                               intel_pt_log("ERROR: failed to read at %" PRIu64 " ", offset);
> +                               if (intel_pt_enable_logging)
> +                                       dso__fprintf(al.map->dso, intel_pt_log_fp());
>                                 return -EINVAL;
> +                       }
>
>                         if (intel_pt_get_insn(buf, len, x86_64, intel_pt_insn))
>                                 return -EINVAL;
> --
> 2.25.1
>