linux-kernel - Re: [PATCH v8 2/4] libperf: Add evsel mmap support

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Date:   Thu, 15 Apr 2021 01:41:35 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Mark Rutland <mark.rutland@....com>,
        Itaru Kitayama <itaru.kitayama@...il.com>
Subject: Re: [PATCH v8 2/4] libperf: Add evsel mmap support

Hello,

On Thu, Apr 15, 2021 at 1:07 AM Rob Herring <robh@...nel.org> wrote:
> +void *perf_evsel__mmap_base(struct perf_evsel *evsel, int cpu, int thread)
> +{
> +       if (FD(evsel, cpu, thread) < 0 || MMAP(evsel, cpu, thread) == NULL)
> +               return NULL;

I think you should check the cpu and the thread is in
a valid range.  Currently xyarray__entry() simply accesses
the content without checking the boundaries.

Thanks,
Namhyung


> +
> +       return MMAP(evsel, cpu, thread)->base;
> +}
> +
>  int perf_evsel__read_size(struct perf_evsel *evsel)
>  {
>         u64 read_format = evsel->attr.read_format;
> diff --git a/tools/lib/perf/include/internal/evsel.h b/tools/lib/perf/include/internal/evsel.h
> index 1ffd083b235e..1c067d088bc6 100644
> --- a/tools/lib/perf/include/internal/evsel.h
> +++ b/tools/lib/perf/include/internal/evsel.h
> @@ -41,6 +41,7 @@ struct perf_evsel {
>         struct perf_cpu_map     *own_cpus;
>         struct perf_thread_map  *threads;
>         struct xyarray          *fd;
> +       struct xyarray          *mmap;
>         struct xyarray          *sample_id;
>         u64                     *id;
>         u32                      ids;
> diff --git a/tools/lib/perf/include/perf/evsel.h b/tools/lib/perf/include/perf/evsel.h
> index c82ec39a4ad0..60eae25076d3 100644
> --- a/tools/lib/perf/include/perf/evsel.h
> +++ b/tools/lib/perf/include/perf/evsel.h
> @@ -27,6 +27,9 @@ LIBPERF_API int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *
>                                  struct perf_thread_map *threads);
>  LIBPERF_API void perf_evsel__close(struct perf_evsel *evsel);
>  LIBPERF_API void perf_evsel__close_cpu(struct perf_evsel *evsel, int cpu);
> +LIBPERF_API int perf_evsel__mmap(struct perf_evsel *evsel, int pages);
> +LIBPERF_API void perf_evsel__munmap(struct perf_evsel *evsel);
> +LIBPERF_API void *perf_evsel__mmap_base(struct perf_evsel *evsel, int cpu, int thread);
>  LIBPERF_API int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,
>                                  struct perf_counts_values *count);
>  LIBPERF_API int perf_evsel__enable(struct perf_evsel *evsel);
> diff --git a/tools/lib/perf/libperf.map b/tools/lib/perf/libperf.map
> index 7be1af8a546c..c0c7ceb11060 100644
> --- a/tools/lib/perf/libperf.map
> +++ b/tools/lib/perf/libperf.map
> @@ -23,6 +23,9 @@ LIBPERF_0.0.1 {
>                 perf_evsel__disable;
>                 perf_evsel__open;
>                 perf_evsel__close;
> +               perf_evsel__mmap;
> +               perf_evsel__munmap;
> +               perf_evsel__mmap_base;
>                 perf_evsel__read;
>                 perf_evsel__cpus;
>                 perf_evsel__threads;
> --
> 2.27.0