From: Rob Herring <robh@kernel.org>
To: Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Mark Rutland <mark.rutland@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Jiri Olsa <jolsa@redhat.com>,
Kan Liang <kan.liang@linux.intel.com>,
Ian Rogers <irogers@google.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
honnappa.nagarahalli@arm.com, Zachary.Leaf@arm.com,
Raphael Gault <raphael.gault@arm.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Namhyung Kim <namhyung@kernel.org>,
Itaru Kitayama <itaru.kitayama@gmail.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v8 2/5] perf: Track per-PMU sched_task() callback users
Date: Mon, 17 May 2021 14:54:02 -0500 [thread overview]
Message-ID: <20210517195405.3079458-3-robh@kernel.org> (raw)
In-Reply-To: <20210517195405.3079458-1-robh@kernel.org>
From: Kan Liang <kan.liang@linux.intel.com>
Current perf only tracks the per-CPU sched_task() callback users, which
doesn't work if a callback user is a task. For example, the dirty
counters have to be cleared to prevent data leakage when a new userspace
access task is scheduled in. The task may be created on one CPU but
running on another CPU. It cannot be tracked by the per-CPU variable. A
global variable is not going to work either because of the hybrid PMUs.
Add a per-PMU variable to track the callback users.
Suggested-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
[robh: Also call sched_task() got sched out cases]
Signed-off-by: Rob Herring <robh@kernel.org>
---
include/linux/perf_event.h | 3 +++
kernel/events/core.c | 8 +++++---
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 4cf081e22b76..a88d52e80864 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -300,6 +300,9 @@ struct pmu {
/* number of address filters this PMU can do */
unsigned int nr_addr_filters;
+ /* Track the per PMU sched_task() callback users */
+ atomic_t sched_cb_usage;
+
/*
* Fully disable/enable this PMU, can be used to protect from the PMI
* as well as for lazy/batch writing of the MSRs.
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2e947a485898..6d0507c23240 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3448,7 +3448,8 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
perf_pmu_disable(pmu);
- if (cpuctx->sched_cb_usage && pmu->sched_task)
+ if (pmu->sched_task &&
+ (cpuctx->sched_cb_usage || atomic_read(&pmu->sched_cb_usage)))
pmu->sched_task(ctx, false);
/*
@@ -3488,7 +3489,8 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
raw_spin_lock(&ctx->lock);
perf_pmu_disable(pmu);
- if (cpuctx->sched_cb_usage && pmu->sched_task)
+ if (pmu->sched_task &&
+ (cpuctx->sched_cb_usage || atomic_read(&pmu->sched_cb_usage)))
pmu->sched_task(ctx, false);
task_ctx_sched_out(cpuctx, ctx, EVENT_ALL);
@@ -3851,7 +3853,7 @@ static void perf_event_context_sched_in(struct perf_event_context *ctx,
cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
perf_event_sched_in(cpuctx, ctx, task);
- if (cpuctx->sched_cb_usage && pmu->sched_task)
+ if (pmu->sched_task && (cpuctx->sched_cb_usage || atomic_read(&pmu->sched_cb_usage)))
pmu->sched_task(cpuctx->task_ctx, true);
perf_pmu_enable(pmu);
--
2.27.0
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next prev parent reply other threads:[~2021-05-17 19:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-17 19:54 [PATCH v8 0/5] arm64 userspace counter support Rob Herring
2021-05-17 19:54 ` [PATCH v8 1/5] perf: Add a counter for number of user access events in context Rob Herring
2021-05-17 19:54 ` Rob Herring [this message]
2021-05-17 19:54 ` [PATCH v8 3/5] arm64: perf: Enable PMU counter userspace access for perf event Rob Herring
2021-06-01 13:55 ` Mark Rutland
2021-06-01 15:00 ` Rob Herring
2021-06-01 17:11 ` Mark Rutland
2021-06-03 16:40 ` Rob Herring
2021-07-21 15:59 ` Rob Herring
2021-05-17 19:54 ` [PATCH v8 4/5] arm64: perf: Add userspace counter access disable switch Rob Herring
2021-06-01 12:57 ` Will Deacon
2021-05-17 19:54 ` [PATCH v8 5/5] Documentation: arm64: Document PMU counters access from userspace Rob Herring
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