This is a note to let you know that I've just added the patch titled
drivers/perf: riscv: Disable PERF_SAMPLE_BRANCH_* while not supported
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drivers-perf-riscv-disable-perf_sample_branch_-while.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 166886afd0e3fa2690e8d2e099c9b75d3b19c7af
Author: Pu Lehui <pulehui@xxxxxxxxxx>
Date: Tue Mar 12 01:20:53 2024 +0000
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 [0]
Fixes: f5bfa23f576f ("RISC-V: Add a perf core library for pmu drivers")
Signed-off-by: Pu Lehui <pulehui@xxxxxxxxxx>
Reviewed-by: Atish Patra <atishp@xxxxxxxxxxxx>
Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240312012053.1178140-1-pulehui@xxxxxxxxxxxxxxx
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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) {
