[PATCH v2 1/1] perf: RISC-V: Limit the number of counters returned from SBI

[Atish Patra]

On Thu, May 4, 2023 at 8:25 PM Viacheslav Mitrofanov
<v.v.mitrofanov at yadro.com> wrote:
>
> Perf gets the number of supported counters from SBI. If it happens that
> the number of returned counters more than RISCV_MAX_COUNTERS the code
> trusts it. It does not lead to an immediate problem but can potentially
> lead to it. Prevent getting more than RISCV_MAX_COUNTERS from SBI.
>
> Signed-off-by: Viacheslav Mitrofanov <v.v.mitrofanov at yadro.com>
> Reviewed-by: Andrew Jones <ajones at ventanamicro.com>
> ---
> Changes in v2:
> - Add new line
> - Substitute pr_warn for pr_info
>
>  drivers/perf/riscv_pmu_sbi.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> index 70cb50fd41c2..9d07af2b6be0 100644
> --- a/drivers/perf/riscv_pmu_sbi.c
> +++ b/drivers/perf/riscv_pmu_sbi.c
> @@ -868,6 +868,12 @@ static int pmu_sbi_device_probe(struct platform_device *pdev)
>                 goto out_free;
>         }
>
> +       /* It is possible to get from SBI more than max number of counters */
> +       if (num_counters > RISCV_MAX_COUNTERS) {
> +               pr_info("SBI returned more than maximum number of counters\n");

Being a little verbose to provide a clear message ?
"Limiting the number of counters to %d


> +               num_counters = RISCV_MAX_COUNTERS;
> +       }
> +
>         /* cache all the information about counters now */
>         if (pmu_sbi_get_ctrinfo(num_counters, &cmask))
>                 goto out_free;
> --
> 2.37.2
>
>

Otherwise, LGTM.
Reviewed-by: Atish Patra <atishp at rivosinc.com>


--
Regards,
Atish