[PATCH v3 1/4] lib: sbi: Fix counter index sanity check

[Atish Patra]

The current implementation computes the possible counter range
by doing a left shift of counter base. However, this may overflow depending
on the counter base value. In case of overflow, the highest counter id
may be computed incorrectly. As per the SBI specification, the respective
function should return an error if any of the counter is not valid.

Fix the counter index check by avoiding left shifting while doing the
sanity checks. Without the shift, the implementation just iterates
over the counter mask and computes the correct counter index by adding
the base to it.

Reviewed-by: Andrew Jones <ajones at ventanamicro.com>
Signed-off-by: Atish Patra <atishp at rivosinc.com>
---
 lib/sbi/sbi_pmu.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/lib/sbi/sbi_pmu.c b/lib/sbi/sbi_pmu.c
index 3f5fd1031b25..31631a2fab80 100644
--- a/lib/sbi/sbi_pmu.c
+++ b/lib/sbi/sbi_pmu.c
@@ -343,25 +343,26 @@ int sbi_pmu_ctr_start(unsigned long cbase, unsigned long cmask,
 {
 	int event_idx_type;
 	uint32_t event_code;
-	unsigned long ctr_mask = cmask << cbase;
 	int ret = SBI_EINVAL;
 	bool bUpdate = FALSE;
+	int i, cidx;
 
-	if (sbi_fls(ctr_mask) >= total_ctrs)
+	if ((cbase + sbi_fls(cmask)) >= total_ctrs)
 		return ret;
 
 	if (flags & SBI_PMU_START_FLAG_SET_INIT_VALUE)
 		bUpdate = TRUE;
 
-	for_each_set_bit_from(cbase, &ctr_mask, total_ctrs) {
-		event_idx_type = pmu_ctr_validate(cbase, &event_code);
+	for_each_set_bit(i, &cmask, total_ctrs) {
+		cidx = i + cbase;
+		event_idx_type = pmu_ctr_validate(cidx, &event_code);
 		if (event_idx_type < 0)
 			/* Continue the start operation for other counters */
 			continue;
 		else if (event_idx_type == SBI_PMU_EVENT_TYPE_FW)
-			ret = pmu_ctr_start_fw(cbase, event_code, ival, bUpdate);
+			ret = pmu_ctr_start_fw(cidx, event_code, ival, bUpdate);
 		else
-			ret = pmu_ctr_start_hw(cbase, ival, bUpdate);
+			ret = pmu_ctr_start_hw(cidx, ival, bUpdate);
 	}
 
 	return ret;
@@ -421,25 +422,26 @@ int sbi_pmu_ctr_stop(unsigned long cbase, unsigned long cmask,
 	int ret = SBI_EINVAL;
 	int event_idx_type;
 	uint32_t event_code;
-	unsigned long ctr_mask = cmask << cbase;
+	int i, cidx;
 
-	if (sbi_fls(ctr_mask) >= total_ctrs)
+	if ((cbase + sbi_fls(cmask)) >= total_ctrs)
 		return SBI_EINVAL;
 
-	for_each_set_bit_from(cbase, &ctr_mask, total_ctrs) {
-		event_idx_type = pmu_ctr_validate(cbase, &event_code);
+	for_each_set_bit(i, &cmask, total_ctrs) {
+		cidx = i + cbase;
+		event_idx_type = pmu_ctr_validate(cidx, &event_code);
 		if (event_idx_type < 0)
 			/* Continue the stop operation for other counters */
 			continue;
 
 		else if (event_idx_type == SBI_PMU_EVENT_TYPE_FW)
-			ret = pmu_ctr_stop_fw(cbase, event_code);
+			ret = pmu_ctr_stop_fw(cidx, event_code);
 		else
-			ret = pmu_ctr_stop_hw(cbase);
+			ret = pmu_ctr_stop_hw(cidx);
 
 		if (flag & SBI_PMU_STOP_FLAG_RESET) {
-			active_events[hartid][cbase] = SBI_PMU_EVENT_IDX_INVALID;
-			pmu_reset_hw_mhpmevent(cbase);
+			active_events[hartid][cidx] = SBI_PMU_EVENT_IDX_INVALID;
+			pmu_reset_hw_mhpmevent(cidx);
 		}
 	}
 
@@ -615,10 +617,9 @@ int sbi_pmu_ctr_cfg_match(unsigned long cidx_base, unsigned long cidx_mask,
 	int event_type = get_cidx_type(event_idx);
 	struct sbi_pmu_fw_event *fevent;
 	uint32_t fw_evt_code;
-	unsigned long tmp = cidx_mask << cidx_base;
 
 	/* Do a basic sanity check of counter base & mask */
-	if (sbi_fls(tmp) >= total_ctrs || event_type >= SBI_PMU_EVENT_TYPE_MAX)
+	if ((cidx_base + sbi_fls(cidx_mask)) >= total_ctrs || event_type >= SBI_PMU_EVENT_TYPE_MAX)
 		return SBI_EINVAL;
 
 	if (flags & SBI_PMU_CFG_FLAG_SKIP_MATCH) {
-- 
2.25.1