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From: Jiri Olsa <jolsa@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Olsa <jolsa@kernel.org>, lkml <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@kernel.org>, Andi Kleen <andi@firstfloor.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Vince Weaver <vince@deater.net>
Subject: [PATCH] perf/x86: Reject non sampling events with precise_ip
Date: Tue, 3 Jan 2017 15:24:54 +0100
Message-ID: <20170103142454.GA26251@krava> (raw)
In-Reply-To: <20170103094059.GC3093@worktop>

On Tue, Jan 03, 2017 at 10:40:59AM +0100, Peter Zijlstra wrote:
> On Wed, Dec 28, 2016 at 02:31:04PM +0100, Jiri Olsa wrote:
> > When in counting mode we setup the counter with the
> > longest possible period and read the value with read
> > syscall.
> > 
> > We also still setup the PMI to be triggered when such
> > counter overflow to reconfigure it.
> > 
> > We also get PEBS interrupt if such counter has precise_ip
> > set (which makes no sense, but it's possible).
> 
> I think we should reject non sampling pebs events, as you say they make
> no sense what so ever.

ook, attached

jirka


---
As Peter suggested [1] rejecting non sampling PEBS events,
because they dont make any sense and could cause issues
in NMI handler [2].

[1] http://lkml.kernel.org/r/20170103094059.GC3093@worktop
[2] http://lkml.kernel.org/r/1482931866-6018-3-git-send-email-jolsa@kernel.org

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 arch/x86/events/core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 64582cfa6976..48b851f0ef89 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -505,6 +505,10 @@ int x86_pmu_hw_config(struct perf_event *event)
 
 		if (event->attr.precise_ip > precise)
 			return -EOPNOTSUPP;
+
+		/* There's no sense in having PEBS for non sampling events. */
+		if (!is_sampling_event(event))
+			return -EINVAL;
 	}
 	/*
 	 * check that PEBS LBR correction does not conflict with
-- 
2.9.3

  reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-28 13:31 [PATCH 0/4] perf: Fuzzer fixes Jiri Olsa
2016-12-28 13:31 ` [PATCH 1/4] perf/x86/intel: Account interrupts for PEBS errors Jiri Olsa
2017-01-14 12:29   ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2016-12-28 13:31 ` [PATCH 2/4] perf/x86: Fix period for non sampling events Jiri Olsa
2017-01-03  9:40   ` Peter Zijlstra
2017-01-03 14:24     ` Jiri Olsa [this message]
2017-01-03 22:06       ` [PATCH] perf/x86: Reject non sampling events with precise_ip Vince Weaver
2017-01-14 12:29       ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2017-01-03 15:09   ` [PATCH 2/4] perf/x86: Fix period for non sampling events Peter Zijlstra
2017-01-03 15:26     ` Jiri Olsa
2016-12-28 13:31 ` [PATCH 3/4] perf: Add perf_event_overflow_throttle function Jiri Olsa
2016-12-28 13:31 ` [PATCH 4/4] perf/x86/intel: Throttle PEBS events only from pmi Jiri Olsa
2017-01-03 13:45   ` Peter Zijlstra
2017-01-24 16:41   ` Peter Zijlstra
2017-01-25 13:02     ` Jiri Olsa
2017-01-25 13:02     ` Jiri Olsa

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