linux-kernel - [PATCH 1/2] events/core: introduce perf_pmu_disable

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Date:   Mon, 23 Nov 2020 13:37:25 +0800
From:   Pingfan Liu <kernelfans@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Pingfan Liu <kernelfans@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Omar Sandoval <osandov@...com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...nel.org>, x86@...nel.org
Subject: [PATCH 1/2] events/core: introduce perf_pmu_disable_all() to turn off all PMU

In crash context, NMI should be suppressed before jump to a new kernel.
Naturally as the source of NMI on some arches, PMU should be turned off at
that time.

Introduce perf_pmu_disable_all() to achieve the goal.

Signed-off-by: Pingfan Liu <kernelfans@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Omar Sandoval <osandov@...com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Mike Rapoport <rppt@...nel.org>
Cc: x86@...nel.org
To: linux-kernel@...r.kernel.org
---
 include/linux/perf_event.h |  1 +
 kernel/events/core.c       | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 96450f6..f4baa87 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -965,6 +965,7 @@ extern const struct perf_event_attr *perf_event_attrs(struct perf_event *event);
 extern void perf_event_print_debug(void);
 extern void perf_pmu_disable(struct pmu *pmu);
 extern void perf_pmu_enable(struct pmu *pmu);
+extern void perf_pmu_disable_all(void);
 extern void perf_sched_cb_dec(struct pmu *pmu);
 extern void perf_sched_cb_inc(struct pmu *pmu);
 extern int perf_event_task_disable(void);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index dc568ca..c8e04a5 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1205,6 +1205,16 @@ void perf_pmu_enable(struct pmu *pmu)
 		pmu->pmu_enable(pmu);
 }
 
+/* When crashed, other cpus hang in idle loop, so here do an emergency job under no lock */
+void perf_pmu_disable_all(void)
+{
+	struct pmu *pmu;
+
+	list_for_each_entry(pmu, &pmus, entry)
+		if (pmu->pmu_disable)
+			pmu->pmu_disable(pmu);
+}
+
 static DEFINE_PER_CPU(struct list_head, active_ctx_list);
 
 /*
-- 
2.7.5