linux-kernel - Re: [PATCH 0/4] riscv: Allow userspace to directly access perf counters

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Date:   Thu, 13 Apr 2023 09:36:23 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Alexandre Ghiti <alexghiti@...osinc.com>
Cc:     Jonathan Corbet <corbet@....net>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Atish Patra <atishp@...shpatra.org>,
        Anup Patel <anup@...infault.org>,
        Will Deacon <will@...nel.org>, Rob Herring <robh@...nel.org>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, paranlee <p4ranlee@...il.com>
Subject: Re: [PATCH 0/4] riscv: Allow userspace to directly access perf counters

On Thu, Apr 13, 2023 at 9:17 AM Alexandre Ghiti <alexghiti@...osinc.com> wrote:
>
> riscv used to allow direct access to cycle/time/instret counters,
> bypassing the perf framework, this patchset intends to allow the user to
> mmap any counter when accessed through perf. But we can't break the
> existing behaviour so we introduce a sysctl perf_user_access like arm64
> does, which defaults to the legacy mode described above.
>
> The core of this patchset lies in patch 4, the first 3 patches are
> simple fixes.
>
> base-commit-tag: v6.3-rc1
>
> Alexandre Ghiti (4):
>   perf: Fix wrong comment about default event_idx
>   include: riscv: Fix wrong include guard in riscv_pmu.h
>   riscv: Make legacy counter enum match the HW numbering
>   riscv: Enable perf counters user access only through perf

Presumably the test also needs patching:
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/tree/tools/perf/tests/mmap-basic.c?h=perf-tools-next#n287

Thanks,
Ian


>  Documentation/admin-guide/sysctl/kernel.rst |  23 +++-
>  arch/riscv/include/asm/perf_event.h         |   3 +
>  arch/riscv/kernel/Makefile                  |   2 +-
>  arch/riscv/kernel/perf_event.c              |  65 +++++++++++
>  drivers/perf/riscv_pmu.c                    |  42 ++++++++
>  drivers/perf/riscv_pmu_legacy.c             |  24 ++++-
>  drivers/perf/riscv_pmu_sbi.c                | 113 ++++++++++++++++++--
>  include/linux/perf/riscv_pmu.h              |   9 +-
>  include/linux/perf_event.h                  |   3 +-
>  tools/lib/perf/mmap.c                       |  65 +++++++++++
>  10 files changed, 332 insertions(+), 17 deletions(-)
>  create mode 100644 arch/riscv/kernel/perf_event.c
>
> --
> 2.37.2
>