From: Raphael Gault <raphael.gault@arm.com>
To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Cc: mark.rutland@arm.com, peterz@infradead.org,
catalin.marinas@arm.com, will.deacon@arm.com, acme@kernel.org,
Raphael Gault <raphael.gault@arm.com>,
mingo@redhat.com
Subject: [PATCH 3/6] arm64: pmu: Add function implementation to update event index in userpage.
Date: Thu, 16 May 2019 14:21:45 +0100 [thread overview]
Message-ID: <20190516132148.10085-4-raphael.gault@arm.com> (raw)
In-Reply-To: <20190516132148.10085-1-raphael.gault@arm.com>
In order to be able to access the counter directly for userspace,
we need to provide the index of the counter using the userpage.
We thus need to override the event_idx function to retrieve and
convert the perf_event index to armv8 hardware index.
Signed-off-by: Raphael Gault <raphael.gault@arm.com>
---
arch/arm64/kernel/perf_event.c | 4 ++++
drivers/perf/arm_pmu.c | 10 ++++++++++
include/linux/perf/arm_pmu.h | 2 ++
3 files changed, 16 insertions(+)
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 6164d389eed6..e6316f99f66b 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -890,6 +890,8 @@ static int __armv8_pmuv3_map_event(struct perf_event *event,
if (armv8pmu_event_is_64bit(event))
event->hw.flags |= ARMPMU_EVT_64BIT;
+ event->hw.flags |= ARMPMU_EL0_RD_CNTR;
+
/* Only expose micro/arch events supported by this PMU */
if ((hw_event_id > 0) && (hw_event_id < ARMV8_PMUV3_MAX_COMMON_EVENTS)
&& test_bit(hw_event_id, armpmu->pmceid_bitmap)) {
@@ -1188,6 +1190,8 @@ void arch_perf_update_userpage(struct perf_event *event,
*/
freq = arch_timer_get_rate();
userpg->cap_user_time = 1;
+ userpg->cap_user_rdpmc =
+ !!(event->hw.flags & ARMPMU_EL0_RD_CNTR);
clocks_calc_mult_shift(&userpg->time_mult, &shift, freq,
NSEC_PER_SEC, 0);
diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index eec75b97e7ea..3f4c2ec7ff89 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -777,6 +777,15 @@ static void cpu_pmu_destroy(struct arm_pmu *cpu_pmu)
&cpu_pmu->node);
}
+
+static int armpmu_event_idx(struct perf_event *event)
+{
+ if (!(event->hw.flags & ARMPMU_EL0_RD_CNTR))
+ return 0;
+
+ return event->hw.idx;
+}
+
static struct arm_pmu *__armpmu_alloc(gfp_t flags)
{
struct arm_pmu *pmu;
@@ -803,6 +812,7 @@ static struct arm_pmu *__armpmu_alloc(gfp_t flags)
.start = armpmu_start,
.stop = armpmu_stop,
.read = armpmu_read,
+ .event_idx = armpmu_event_idx,
.filter_match = armpmu_filter_match,
.attr_groups = pmu->attr_groups,
/*
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index 4641e850b204..3bef390c1069 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -30,6 +30,8 @@
*/
/* Event uses a 64bit counter */
#define ARMPMU_EVT_64BIT 1
+/* Allow access to hardware counter from userspace */
+#define ARMPMU_EL0_RD_CNTR 2
#define HW_OP_UNSUPPORTED 0xFFFF
#define C(_x) PERF_COUNT_HW_CACHE_##_x
--
2.17.1
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next prev parent reply other threads:[~2019-05-16 13:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-16 13:21 [RFC 0/6] arm64: Enable access to pmu registers by user-space Raphael Gault
2019-05-16 13:21 ` [PATCH 1/6] perf: arm64: Compile tests unconditionally Raphael Gault
2019-05-16 13:21 ` [PATCH 2/6] perf: arm64: Add test to check userspace access to hardware counters Raphael Gault
2019-05-16 13:21 ` Raphael Gault [this message]
2019-05-17 13:21 ` [PATCH 3/6] arm64: pmu: Add function implementation to update event index in userpage Mark Rutland
2019-05-16 13:21 ` [PATCH 4/6] arm64: pmu: Add hook to handle pmu-related undefined instructions Raphael Gault
2019-05-17 7:10 ` Peter Zijlstra
2019-05-17 7:35 ` Raphael Gault
2019-05-17 8:04 ` Mark Rutland
2019-05-17 8:26 ` Peter Zijlstra
2019-05-17 9:07 ` Peter Zijlstra
2019-05-16 13:21 ` [PATCH 5/6] arm64: perf: Enable pmu counter direct access for perf event on armv8 Raphael Gault
2019-05-16 13:21 ` [PATCH 6/6] Documentation: arm64: Document PMU counters access from userspace Raphael Gault
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