From: Will Deacon <will@kernel.org>
To: Sergey Matyukevich <geomatsi@gmail.com>
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
linux-perf-users@vger.kernel.org, Paul Walmsley <pjw@kernel.org>,
Palmer Dabbelt <palmer@dabbelt.com>,
Alexandre Ghiti <alex@ghiti.fr>,
Atish Patra <atish.patra@linux.dev>,
Anup Patel <anup@brainfault.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH] drivers/perf: riscv: handle legacy fallback in event check
Date: Fri, 31 Jul 2026 17:35:16 +0100 [thread overview]
Message-ID: <amzOxPgM2v6O9XqD@google.com> (raw)
In-Reply-To: <20260710100837.1362558-1-geomatsi@gmail.com>
On Fri, Jul 10, 2026 at 01:08:35PM +0300, Sergey Matyukevich wrote:
> Common events PERF_COUNT_HW_CPU_CYCLES and PERF_COUNT_HW_INSTRUCTIONS
> can fall back to the legacy counters. So do not mark them as invalid
> if OpenSBI reports that they are not mapped to sampling counters
> in PMU DT node.
>
> Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com>
> ---
> drivers/perf/riscv_pmu_sbi.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> index dfc886dee5ad..8f7aa71dc96f 100644
> --- a/drivers/perf/riscv_pmu_sbi.c
> +++ b/drivers/perf/riscv_pmu_sbi.c
> @@ -335,7 +335,8 @@ static int pmu_sbi_check_event_info(void)
> goto free_mem;
> }
>
> - for (i = 0; i < ARRAY_SIZE(pmu_hw_event_map); i++) {
> + /* skip check for cycles and instructions as they can fall back to legacy counters */
> + for (i = 2; i < ARRAY_SIZE(pmu_hw_event_map); i++) {
> if (!(event_info_shmem[i].output & RISCV_PMU_EVENT_INFO_OUTPUT_MASK))
> pmu_hw_event_map[i].event_idx = -ENOENT;
> }
I'm assuming the riscv tree are handling perf patches to the riscv driver,
but please shout if not.
Will
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prev parent reply other threads:[~2026-07-31 16:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-10 10:08 [PATCH] drivers/perf: riscv: handle legacy fallback in event check Sergey Matyukevich
2026-07-31 16:35 ` Will Deacon [this message]
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