queue-6.6/drivers-perf-riscv-disable-perf_sample_branch_-while.patch

   1 From d71a39d2ed9c2646aff2590b4f7591aa24957f58 Mon Sep 17 00:00:00 2001
   2 From: Sasha Levin <sashal@kernel.org>
   3 Date: Tue, 12 Mar 2024 01:20:53 +0000
   4 Subject: drivers/perf: riscv: Disable PERF_SAMPLE_BRANCH_* while not supported
   5
   6 From: Pu Lehui <pulehui@huawei.com>
   7
   8 [ Upstream commit ea6873118493019474abbf57d5a800da365734df ]
   9
  10 RISC-V perf driver does not yet support branch sampling. Although the
  11 specification is in the works [0], it is best to disable such events
  12 until support is available, otherwise we will get unexpected results.
  13 Due to this reason, two riscv bpf testcases get_branch_snapshot and
  14 perf_branches/perf_branches_hw fail.
  15
  16 Link: https://github.com/riscv/riscv-control-transfer-records [0]
  17 Fixes: f5bfa23f576f ("RISC-V: Add a perf core library for pmu drivers")
  18 Signed-off-by: Pu Lehui <pulehui@huawei.com>
  19 Reviewed-by: Atish Patra <atishp@rivosinc.com>
  20 Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
  21 Link: https://lore.kernel.org/r/20240312012053.1178140-1-pulehui@huaweicloud.com
  22 Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
  23 Signed-off-by: Sasha Levin <sashal@kernel.org>
  24 ---
  25  drivers/perf/riscv_pmu.c | 4 ++++
  26  1 file changed, 4 insertions(+)
  27
  28 diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
  29 index c78a6fd6c57f6..b4efdddb2ad91 100644
  30 --- a/drivers/perf/riscv_pmu.c
  31 +++ b/drivers/perf/riscv_pmu.c
  32 @@ -313,6 +313,10 @@ static int riscv_pmu_event_init(struct perf_event *event)
  33         u64 event_config = 0;
  34         uint64_t cmask;
  35
  36 +       /* driver does not support branch stack sampling */
  37 +       if (has_branch_stack(event))
  38 +               return -EOPNOTSUPP;
  39 +
  40         hwc->flags = 0;
  41         mapped_event = rvpmu->event_map(event, &event_config);
  42         if (mapped_event < 0) {
  43 --
  44 2.43.0
  45