From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755527Ab2A0VBx (ORCPT ); Fri, 27 Jan 2012 16:01:53 -0500 Received: from mail-wi0-f174.google.com ([209.85.212.174]:50639 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755056Ab2A0U6d (ORCPT ); Fri, 27 Jan 2012 15:58:33 -0500 From: Stephane Eranian To: linux-kernel@vger.kernel.org Cc: peterz@infradead.org, mingo@elte.hu, acme@redhat.com, robert.richter@amd.com, ming.m.lin@intel.com, andi@firstfloor.org, asharma@fb.com, ravitillo@lbl.gov, vweaver1@eecs.utk.edu, khandual@linux.vnet.ibm.com, dsahern@gmail.com Subject: [PATCH v4 06/18] perf: disable LBR support for older Intel Atom processors Date: Fri, 27 Jan 2012 21:56:06 +0100 Message-Id: <1327697778-18515-7-git-send-email-eranian@google.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1327697778-18515-1-git-send-email-eranian@google.com> References: <1327697778-18515-1-git-send-email-eranian@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The patch adds a restriction for Intel Atom LBR support. Only steppings 10 (PineView) and more recent are supported. Older models, do not have a functional LBR. Their LBR does not freeze on PMU interrupt which makes LBR unusable in the context of perf_events. Signed-off-by: Stephane Eranian --- arch/x86/kernel/cpu/perf_event_intel_lbr.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index 8a1eb6c..e2b7094 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -313,6 +313,16 @@ void intel_pmu_lbr_init_snb(void) /* atom */ void intel_pmu_lbr_init_atom(void) { + /* + * only models starting at stepping 10 seems + * to have an operational LBR which can freeze + * on PMU interrupt + */ + if (boot_cpu_data.x86_mask < 10) { + pr_cont("LBR disabled due to erratum"); + return; + } + x86_pmu.lbr_nr = 8; x86_pmu.lbr_tos = MSR_LBR_TOS; x86_pmu.lbr_from = MSR_LBR_CORE_FROM; -- 1.7.1