Re: [PATCH] RISC-V: Skip stopping cycle counter

From: Qingwei Hu <redacted>

In the riscv_pmu_sbi driver, pmu_sbi_stop_all() is intended to stop
all available counters. However, counter 0 (the cycle counter) should
be excluded from this operation because the counter may be used in
user mode by rdcycle.

Signed-off-by: Qingwei Hu <redacted>
---
 drivers/perf/riscv_pmu_sbi.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
index 7dd282da67ce..2bc0050dabd2 100644
--- a/drivers/perf/riscv_pmu_sbi.c
+++ b/drivers/perf/riscv_pmu_sbi.c

@@ -900,11 +900,15 @@ static int pmu_sbi_get_ctrinfo(int nctr, unsigned long *mask)
 static inline void pmu_sbi_stop_all(struct riscv_pmu *pmu)
 {
        /*
-        * No need to check the error because we are disabling all the counters
-        * which may include counters that are not enabled yet.
+        * No need to check the error because we are disabling all available
+        * counters (except the cycle counter) which may include counters
+        * that are not enabled yet.
+        *
+        * Cycle counter is excluded because it might be accessed by user
+        * mode via rdcycle.
         */
        sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP,
-                 0, pmu->cmask, SBI_PMU_STOP_FLAG_RESET, 0, 0, 0);
+                 0, pmu->cmask & ~BIT(0), SBI_PMU_STOP_FLAG_RESET, 0, 0, 0);