[PATCH 2/2] arm: perf: Fix ARCH=arm build with GCC in armv8pmu_set_event_filter()

[James Clark]

LLVM ignores everything inside the if statement and doesn't generate
errors, but GCC does, resulting in the following:

  drivers/perf/arm_pmuv3.c: In function armv8pmu_set_event_filter:
  include/linux/bits.h:34:29: error: left shift count >= width of type [-Werror=shift-count-overflow]
  34 |         (((~UL(0)) - (UL(1) << (l)) + 1) & \

Fix it by changing the if to #if. This results in an unused function
warning for armv8pmu_event_threshold_control(), so suppress that too.

Fixes: 816c26754447 ("arm64: perf: Add support for event counting threshold")
Signed-off-by: James Clark <james.clark@xxxxxxx>
---
 drivers/perf/arm_pmuv3.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
index 3ed2086cefc3..8aa23878019a 100644
--- a/drivers/perf/arm_pmuv3.c
+++ b/drivers/perf/arm_pmuv3.c
@@ -338,7 +338,7 @@ static bool armv8pmu_event_want_user_access(struct perf_event *event)
 	return ATTR_CFG_GET_FLD(&event->attr, rdpmc);
 }
 
-static u8 armv8pmu_event_threshold_control(struct perf_event_attr *attr)
+static __maybe_unused u8 armv8pmu_event_threshold_control(struct perf_event_attr *attr)
 {
 	u8 th_compare = ATTR_CFG_GET_FLD(attr, threshold_compare);
 	u8 th_count = ATTR_CFG_GET_FLD(attr, threshold_count);
@@ -1040,11 +1040,13 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
 		return -EINVAL;
 	}
 
-	if (IS_ENABLED(CONFIG_ARM64) && th) {
+#if IS_ENABLED(CONFIG_ARM64)
+	if (th) {
 		config_base |= FIELD_PREP(ARMV8_PMU_EVTYPE_TH, th);
 		config_base |= FIELD_PREP(ARMV8_PMU_EVTYPE_TC,
 					  armv8pmu_event_threshold_control(attr));
 	}
+#endif
 
 	/*
 	 * Install the filter into config_base as this is used to
-- 
2.34.1