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From: Leo Yan <leo.yan@linaro.org>
To: Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Paul Cercueil <paul@crapouillou.net>,
	"Ben Dooks (Codethink)" <ben.dooks@codethink.co.uk>,
	"Ahmed S. Darwish" <a.darwish@linutronix.de>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Kan Liang <kan.liang@linux.intel.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 3/6] arm64: perf: Only advertise cap_user_time for arch_timer
Date: Wed, 15 Jul 2020 10:05:09 +0800	[thread overview]
Message-ID: <20200715020512.20991-4-leo.yan@linaro.org> (raw)
In-Reply-To: <20200715020512.20991-1-leo.yan@linaro.org>

From: Peter Zijlstra <peterz@infradead.org>

When sched_clock is running on anything other than arch_timer, don't
advertise cap_user_time*.

Requested-by: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/arm64/kernel/perf_event.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 35c2c737d4af..76f6afd28b48 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -13,6 +13,8 @@
 #include <asm/sysreg.h>
 #include <asm/virt.h>
 
+#include <clocksource/arm_arch_timer.h>
+
 #include <linux/acpi.h>
 #include <linux/clocksource.h>
 #include <linux/kvm_host.h>
@@ -1170,16 +1172,15 @@ void arch_perf_update_userpage(struct perf_event *event,
 	unsigned int seq;
 	u64 quot, rem, ns;
 
-	/*
-	 * Internal timekeeping for enabled/running/stopped times
-	 * is always computed with the sched_clock.
-	 */
-	userpg->cap_user_time = 1;
-	userpg->cap_user_time_zero = 1;
+	userpg->cap_user_time = 0;
+	userpg->cap_user_time_zero = 0;
 
 	do {
 		rd = sched_clock_read_begin(&seq);
 
+		if (rd->read_sched_clock != arch_timer_read_counter)
+			return;
+
 		userpg->time_mult = rd->mult;
 		userpg->time_shift = rd->shift;
 		userpg->time_zero = rd->epoch_ns;
@@ -1211,4 +1212,10 @@ void arch_perf_update_userpage(struct perf_event *event,
 		userpg->time_mult >>= 1;
 	}
 
+	/*
+	 * Internal timekeeping for enabled/running/stopped times
+	 * is always computed with the sched_clock.
+	 */
+	userpg->cap_user_time = 1;
+	userpg->cap_user_time_zero = 1;
 }
-- 
2.17.1


  parent reply	other threads:[~2020-07-15  2:05 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-15  2:05 [PATCH v2 0/6] arm64: perf: Proper cap_user_time* support Leo Yan
2020-07-15  2:05 ` [PATCH v2 1/6] sched_clock: Expose struct clock_read_data Leo Yan
2020-07-15  5:56   ` Ahmed S. Darwish
2020-07-15  6:54     ` Leo Yan
2020-07-15  7:21       ` Ahmed S. Darwish
2020-07-15  8:12     ` Peter Zijlstra
2020-07-15  8:14       ` peterz
2020-07-15  9:23         ` Ahmed S. Darwish
2020-07-15  9:52           ` Peter Zijlstra
2020-07-15 11:59             ` [PATCH] time/sched_clock: Use raw_read_seqcount_latch() Ahmed S. Darwish
2020-07-15 15:29               ` Leo Yan
2020-07-15 15:58                 ` Peter Zijlstra
2020-07-16  5:22                   ` Leo Yan
2020-09-10 15:08           ` [tip: locking/core] time/sched_clock: Use raw_read_seqcount_latch() during suspend tip-bot2 for Ahmed S. Darwish
2020-07-15  2:05 ` [PATCH v2 2/6] arm64: perf: Implement correct cap_user_time Leo Yan
2020-07-15  8:38   ` Peter Zijlstra
2020-07-15 15:39     ` Leo Yan
2020-07-15  2:05 ` Leo Yan [this message]
2020-07-15  2:05 ` [PATCH v2 4/6] perf: Add perf_event_mmap_page::cap_user_time_short ABI Leo Yan
2020-07-15  2:05 ` [PATCH v2 5/6] arm64: perf: Add cap_user_time_short Leo Yan
2020-07-15  2:05 ` [PATCH v2 6/6] tools headers UAPI: Update tools's copy of linux/perf_event.h Leo Yan
2020-07-15  5:17 ` [PATCH v2 0/6] arm64: perf: Proper cap_user_time* support Ahmed S. Darwish
2020-07-15  6:29   ` Leo Yan

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