perf/arm-ni: Fix and optimise register offset calculation

LKP points out an operator precedence oversight in the new NoC S3
support that, annoyingly, my local W=1 build didn't flag. In fixing
that, we can also take the similarly-missed opportunity to cache the
version check itself at event_init time.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511041749.ok8zDP6u-lkp@intel.com/
Fixes: 8fa08f8 ("perf/arm-ni: Add NoC S3 support")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

Author: rmurphy-arm

drivers/perf/arm-ni.c

@@ -323,17 +323,26 @@ static int arm_ni_validate_group(struct perf_event *event)
 	return 0;
 }
 
+static bool arm_ni_is_7xx(const struct arm_ni *ni)
+{
+	return ni->part == PART_NI_700 || ni->part == PART_NI_710AE;
+}
+
 static int arm_ni_event_init(struct perf_event *event)
 {
 	struct arm_ni_cd *cd = pmu_to_cd(event->pmu);
+	struct arm_ni *ni;
 
 	if (event->attr.type != event->pmu->type)
 		return -ENOENT;
 
 	if (is_sampling_event(event))
 		return -EINVAL;
 
-	event->cpu = cd_to_ni(cd)->cpu;
+	ni = cd_to_ni(cd);
+	event->cpu = ni->cpu;
+	event->hw.flags = arm_ni_is_7xx(ni);
+
 	if (NI_EVENT_TYPE(event) == NI_PMU)
 		return arm_ni_validate_group(event);
 
@@ -411,26 +420,20 @@ static void arm_ni_init_evcnt(struct hw_perf_event *hw)
 	writel_relaxed(S32_MIN, (void __iomem *)hw->event_base);
 }
 
-static bool arm_ni_is_7xx(const struct arm_ni *ni)
-{
-	return ni->part == PART_NI_700 || ni->part == PART_NI_710AE;
-}
-
 static int arm_ni_event_add(struct perf_event *event, int flags)
 {
 	struct arm_ni_cd *cd = pmu_to_cd(event->pmu);
 	struct hw_perf_event *hw = &event->hw;
 	struct arm_ni_unit *unit;
 	enum ni_node_type type = NI_EVENT_TYPE(event);
-	bool is_7xx = arm_ni_is_7xx(cd_to_ni(cd));
 	u32 reg;
 
 	if (type == NI_PMU) {
 		if (cd->ccnt)
 			return -ENOSPC;
 		hw->idx = NI_CCNT_IDX;
 		hw->event_base = (unsigned long)cd->pmu_base +
-				 is_7xx ? NI700_PMCCNTR_L : NI_PMCCNTR_L;
+				 (hw->flags ? NI700_PMCCNTR_L : NI_PMCCNTR_L);
 		cd->ccnt = event;
 		arm_ni_init_ccnt(hw);
 	} else {
@@ -443,7 +446,7 @@ static int arm_ni_event_add(struct perf_event *event, int flags)
 		unit = (void *)hw->config_base;
 		unit->event[hw->idx] = NI_EVENT_EVENTID(event);
 		hw->event_base = (unsigned long)cd->pmu_base +
-				 is_7xx ? NI700_PMEVCNTR(hw->idx) : NI_PMEVCNTR(hw->idx);
+				 (hw->flags ? NI700_PMEVCNTR(hw->idx) : NI_PMEVCNTR(hw->idx));
 		arm_ni_init_evcnt(hw);
 		lo_hi_writeq_relaxed(le64_to_cpu(unit->pmusel), unit->pmusela);