Linux 6.6.26

[thirdparty/kernel/stable-queue.git] / releases / 6.6.26 / drivers-perf-riscv-disable-perf_sample_branch_-while.patch

From d71a39d2ed9c2646aff2590b4f7591aa24957f58 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Tue, 12 Mar 2024 01:20:53 +0000
Subject: drivers/perf: riscv: Disable PERF_SAMPLE_BRANCH_* while not supported

From: Pu Lehui <pulehui@huawei.com>

[ 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 [0]
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>
---
 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 c78a6fd6c57f6..b4efdddb2ad91 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) {
-- 
2.43.0