linux-kernel - [tip:perfcounters/core] perf_counter: x86: Allow unpriviliged use of NMIs

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Message-ID: <tip-a026dfecc035f213c1cfa0bf6407ce3155f6a9df@git.kernel.org>
Date:	Fri, 15 May 2009 08:42:53 GMT
From:	tip-bot for Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, paulus@...ba.org, hpa@...or.com,
	mingo@...hat.com, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
	cjashfor@...ux.vnet.ibm.com, mingo@...e.hu
Subject: [tip:perfcounters/core] perf_counter: x86: Allow unpriviliged use of NMIs

Commit-ID:  a026dfecc035f213c1cfa0bf6407ce3155f6a9df
Gitweb:     http://git.kernel.org/tip/a026dfecc035f213c1cfa0bf6407ce3155f6a9df
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Wed, 13 May 2009 10:02:57 +0200
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 15 May 2009 09:46:57 +0200

perf_counter: x86: Allow unpriviliged use of NMIs

Apply sysctl_perf_counter_priv to NMIs. Also, fail the counter
creation instead of silently down-grading to regular interrupts.

[ Impact: allow wider perf-counter usage ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 arch/x86/kernel/cpu/perf_counter.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 88ae8ce..c19e927 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -280,8 +280,11 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
 	 * If privileged enough, allow NMI events:
 	 */
 	hwc->nmi = 0;
-	if (capable(CAP_SYS_ADMIN) && hw_event->nmi)
+	if (hw_event->nmi) {
+		if (sysctl_perf_counter_priv && !capable(CAP_SYS_ADMIN))
+			return -EACCES;
 		hwc->nmi = 1;
+	}
 
 	hwc->irq_period	= hw_event->irq_period;
 	if ((s64)hwc->irq_period <= 0 || hwc->irq_period > x86_pmu.max_period)
--
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