[PATCH v2] drivers/perf: riscv: Disable PERF_SAMPLE_BRANCH_* while not supported

[Atish Patra]

On Mon, Mar 11, 2024 at 6:19 PM Pu Lehui <pulehui at huaweicloud.com> wrote:
>
> From: Pu Lehui <pulehui at huawei.com>
>
> RISC-V perf driver does not yet support branch sampling. Although the
> specification is in the works [0], it is best to disable such events
> until support is available, otherwise we will get unexpected results.
> Due to this reason, two riscv bpf testcases get_branch_snapshot and
> perf_branches/perf_branches_hw fail.
>
> Link: https://github.com/riscv/riscv-control-transfer-records [0]
> Fixes: f5bfa23f576f ("RISC-V: Add a perf core library for pmu drivers")
> Signed-off-by: Pu Lehui <pulehui at huawei.com>
> ---
>  drivers/perf/riscv_pmu.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
> index c78a6fd6c57f..b4efdddb2ad9 100644
> --- a/drivers/perf/riscv_pmu.c
> +++ b/drivers/perf/riscv_pmu.c
> @@ -313,6 +313,10 @@ static int riscv_pmu_event_init(struct perf_event *event)
>         u64 event_config = 0;
>         uint64_t cmask;
>
> +       /* driver does not support branch stack sampling */
> +       if (has_branch_stack(event))
> +               return -EOPNOTSUPP;
> +
>         hwc->flags = 0;
>         mapped_event = rvpmu->event_map(event, &event_config);
>         if (mapped_event < 0) {
> --
> 2.34.1
>


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