Patch "drivers/perf: riscv: Disable PERF_SAMPLE_BRANCH_* while not supported" has been added to the 6.6-stable tree

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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 6.6-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-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d71a39d2ed9c2646aff2590b4f7591aa24957f58
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) {




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