Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754439AbbBRRR6 (ORCPT ); Wed, 18 Feb 2015 12:17:58 -0500 Received: from terminus.zytor.com ([198.137.202.10]:39526 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754412AbbBRRR4 (ORCPT ); Wed, 18 Feb 2015 12:17:56 -0500 Date: Wed, 18 Feb 2015 09:17:05 -0800 From: "tip-bot for Yan, Zheng" Message-ID: Cc: mingo@kernel.org, tglx@linutronix.de, hpa@zytor.com, torvalds@linux-foundation.org, kan.liang@intel.com, acme@kernel.org, peterz@infradead.org, paulus@samba.org, zheng.z.yan@intel.com, linux-kernel@vger.kernel.org Reply-To: mingo@kernel.org, hpa@zytor.com, torvalds@linux-foundation.org, tglx@linutronix.de, acme@kernel.org, kan.liang@intel.com, peterz@infradead.org, zheng.z.yan@intel.com, paulus@samba.org, linux-kernel@vger.kernel.org In-Reply-To: <1415156173-10035-15-git-send-email-kan.liang@intel.com> References: <1415156173-10035-15-git-send-email-kan.liang@intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf/x86/intel: Disable FREEZE_LBRS_ON_PMI when LBR operates in callstack mode Git-Commit-ID: 2c70d0086e4e9e2440f0f78098090f32bde14277 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2831 Lines: 70 Commit-ID: 2c70d0086e4e9e2440f0f78098090f32bde14277 Gitweb: http://git.kernel.org/tip/2c70d0086e4e9e2440f0f78098090f32bde14277 Author: Yan, Zheng AuthorDate: Tue, 4 Nov 2014 21:56:10 -0500 Committer: Ingo Molnar CommitDate: Wed, 18 Feb 2015 17:16:13 +0100 perf/x86/intel: Disable FREEZE_LBRS_ON_PMI when LBR operates in callstack mode LBR callstack is designed for PEBS, It does not work well with FREEZE_LBRS_ON_PMI for non PEBS event. If FREEZE_LBRS_ON_PMI is set for non PEBS event, PMIs near call/return instructions may cause superfluous increase/decrease of LBR_TOS. This patch modifies __intel_pmu_lbr_enable() to not enable FREEZE_LBRS_ON_PMI when LBR operates in callstack mode. We currently don't use LBR callstack to capture kernel space callchain, so disabling FREEZE_LBRS_ON_PMI should not be a problem. Signed-off-by: Yan, Zheng Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Linus Torvalds Cc: Paul Mackerras Cc: eranian@google.com Cc: jolsa@redhat.com Link: http://lkml.kernel.org/r/1415156173-10035-15-git-send-email-kan.liang@intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event_intel_lbr.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index a8b3f23..92a44fd 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -131,14 +131,23 @@ static void intel_pmu_lbr_filter(struct cpu_hw_events *cpuc); static void __intel_pmu_lbr_enable(void) { - u64 debugctl; struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); + u64 debugctl, lbr_select = 0; - if (cpuc->lbr_sel) - wrmsrl(MSR_LBR_SELECT, cpuc->lbr_sel->config); + if (cpuc->lbr_sel) { + lbr_select = cpuc->lbr_sel->config; + wrmsrl(MSR_LBR_SELECT, lbr_select); + } rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); - debugctl |= (DEBUGCTLMSR_LBR | DEBUGCTLMSR_FREEZE_LBRS_ON_PMI); + debugctl |= DEBUGCTLMSR_LBR; + /* + * LBR callstack does not work well with FREEZE_LBRS_ON_PMI. + * If FREEZE_LBRS_ON_PMI is set, PMI near call/return instructions + * may cause superfluous increase/decrease of LBR_TOS. + */ + if (!(lbr_select & LBR_CALL_STACK)) + debugctl |= DEBUGCTLMSR_FREEZE_LBRS_ON_PMI; wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/