drivers/perf: riscv: Disable PERF_SAMPLE_BRANCH_* while not supported

[ Upstream commit ea6873118493019474abbf57d5a800da365734df ]

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
Fixes: f5bfa23f576f ("RISC-V: Add a perf core library for pmu drivers")
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240312012053.1178140-1-pulehui@huaweicloud.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
index c78a6fd..b4efddd 100644 (file)
--- 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) {