[PATCH] perf: riscv: fix PMU overflow counter restart state

[Pengpeng Hou]

The PMU overflow handler keeps a 64-bit mask for all logical counters,
while SBI start calls consume an XLEN-sized mask relative to a counter
base.

On RV32, pmu_sbi_start_ovf_ctrs_sbi() applies the low overflow-mask word
to every used-counter word. Counters 32 through 63 can therefore be
classified using overflow bits 0 through 31.

The snapshot path and overflow handler also test and construct 64-bit
masks with XLEN-sized BIT(). In addition, snapshot restart uses the
completed inner-loop index instead of the outer word index to form
counter_idx_base. The latter selects an invalid counter base on both RV32
and RV64: for_each_set_bit() finishes with idx equal to BITS_PER_LONG, so
the current expression passes BITS_PER_LONG squared instead of the
expected i times BITS_PER_LONG.

Select the overflow word matching each SBI mask, use 64-bit bit operations
for global counter indices, and derive the snapshot start base from the
outer word index.

Fixes: b994cdfcdf7b ("drivers/perf: riscv: Fix counter mask iteration for RV32")
Fixes: a8625217a054 ("drivers/perf: riscv: Implement SBI PMU snapshot function")
Signed-off-by: Pengpeng Hou <pengpeng@xxxxxxxxxxx>
---
 drivers/perf/riscv_pmu_sbi.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
index 50220f7b46d9..6cfb1fc0ec6e 100644
--- a/drivers/perf/riscv_pmu_sbi.c
+++ b/drivers/perf/riscv_pmu_sbi.c
@@ -962,7 +962,9 @@ static inline void pmu_sbi_start_ovf_ctrs_sbi(struct cpu_hw_events *cpu_hw_evt,
 	u64 init_val = 0;
 
 	for (i = 0; i < BITS_TO_LONGS(RISCV_MAX_COUNTERS); i++) {
-		ctr_start_mask = cpu_hw_evt->used_hw_ctrs[i] & ~ctr_ovf_mask;
+		unsigned long word_ovf_mask =
+			ctr_ovf_mask >> (i * BITS_PER_LONG);
+		ctr_start_mask = cpu_hw_evt->used_hw_ctrs[i] & ~word_ovf_mask;
 		/* Start all the counters that did not overflow in a single shot */
 		if (ctr_start_mask) {
 			sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, i * BITS_PER_LONG,
@@ -1002,7 +1004,7 @@ static inline void pmu_sbi_start_ovf_ctrs_snapshot(struct cpu_hw_events *cpu_hw_
 	struct riscv_pmu_snapshot_data *sdata = cpu_hw_evt->snapshot_addr;
 
 	for_each_set_bit(idx, cpu_hw_evt->used_hw_ctrs, RISCV_MAX_COUNTERS) {
-		if (ctr_ovf_mask & BIT(idx)) {
+		if (ctr_ovf_mask & BIT_ULL(idx)) {
 			event = cpu_hw_evt->events[idx];
 			hwc = &event->hw;
 			max_period = riscv_pmu_ctr_get_width_mask(event);
@@ -1021,7 +1023,7 @@ static inline void pmu_sbi_start_ovf_ctrs_snapshot(struct cpu_hw_events *cpu_hw_
 			sdata->ctr_values[idx] =
 					cpu_hw_evt->snapshot_cval_shcopy[idx + i * BITS_PER_LONG];
 		/* Start all the counters in a single shot */
-		sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, idx * BITS_PER_LONG,
+		sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, i * BITS_PER_LONG,
 			  cpu_hw_evt->used_hw_ctrs[i], flag, 0, 0, 0);
 	}
 }
@@ -1109,14 +1111,14 @@ static irqreturn_t pmu_sbi_ovf_handler(int irq, void *dev)
 			hidx = info->csr - CSR_CYCLE;
 
 		/* check if the corresponding bit is set in scountovf or overflow mask in shmem */
-		if (!(overflow & BIT(hidx)))
+		if (!(overflow & BIT_ULL(hidx)))
 			continue;
 
 		/*
 		 * Keep a track of overflowed counters so that they can be started
 		 * with updated initial value.
 		 */
-		overflowed_ctrs |= BIT(lidx);
+		overflowed_ctrs |= BIT_ULL(lidx);
 		hw_evt = &event->hw;
 		/* Update the event states here so that we know the state while reading */
 		hw_evt->state |= PERF_HES_STOPPED;

base-commit: 1b78070aaef63512688aebfbc82365ef9d6660f1
-- 
2.43.0