From dff5da6d09daaab40a8741dce0ed3c2e94079de2 Mon Sep 17 00:00:00 2001
From: Yong Wang <yong.y.wang@linux.intel.com>
Date: Fri, 12 Jun 2009 16:08:55 +0800
Subject: [PATCH] perf_counter/x86: Add a quirk for Atom processors

The fixed-function performance counters do not work on current Atom
processors. Use the general-purpose ones instead.

Signed-off-by: Yong Wang <yong.y.wang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <20090612080855.GA2286@ywang-moblin2.bj.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/kernel/cpu/perf_counter.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 895c82e78455..275bc142cd5d 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -968,6 +968,13 @@ fixed_mode_idx(struct perf_counter *counter, struct hw_perf_counter *hwc)
 	if (!x86_pmu.num_counters_fixed)
 		return -1;
 
+	/*
+	 * Quirk, IA32_FIXED_CTRs do not work on current Atom processors:
+	 */
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
+					boot_cpu_data.x86_model == 28)
+		return -1;
+
 	event = hwc->config & ARCH_PERFMON_EVENT_MASK;
 
 	if (unlikely(event == x86_pmu.event_map(PERF_COUNT_HW_INSTRUCTIONS)))
-- 
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