[PATCH v3 6/7] arm64: perf: Add cap_user_time_short
Leo Yan
leo.yan at linaro.org
Thu Jul 16 01:11:29 EDT 2020
From: Peter Zijlstra <peterz at infradead.org>
This completes the ARM64 cap_user_time support.
Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org>
Signed-off-by: Leo Yan <leo.yan at linaro.org>
---
arch/arm64/kernel/perf_event.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index c016b116ae33..888bcb5d1388 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -1174,6 +1174,7 @@ void arch_perf_update_userpage(struct perf_event *event,
userpg->cap_user_time = 0;
userpg->cap_user_time_zero = 0;
+ userpg->cap_user_time_short = 0;
do {
rd = sched_clock_read_begin(&seq);
@@ -1184,13 +1185,13 @@ void arch_perf_update_userpage(struct perf_event *event,
userpg->time_mult = rd->mult;
userpg->time_shift = rd->shift;
userpg->time_zero = rd->epoch_ns;
+ userpg->time_cycles = rd->epoch_cyc;
+ userpg->time_mask = rd->sched_clock_mask;
/*
- * This isn't strictly correct, the ARM64 counter can be
- * 'short' and then we get funnies when it wraps. The correct
- * thing would be to extend the perf ABI with a cycle and mask
- * value, but because wrapping on ARM64 is very rare in
- * practise this 'works'.
+ * Subtract the cycle base, such that software that
+ * doesn't know about cap_user_time_short still 'works'
+ * assuming no wraps.
*/
ns = mul_u64_u32_shr(rd->epoch_cyc, rd->mult, rd->shift);
userpg->time_zero -= ns;
@@ -1216,4 +1217,5 @@ void arch_perf_update_userpage(struct perf_event *event,
*/
userpg->cap_user_time = 1;
userpg->cap_user_time_zero = 1;
+ userpg->cap_user_time_short = 1;
}
--
2.17.1
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