From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750929AbXBQQHR (ORCPT ); Sat, 17 Feb 2007 11:07:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750938AbXBQQHR (ORCPT ); Sat, 17 Feb 2007 11:07:17 -0500 Received: from madara.hpl.hp.com ([192.6.19.124]:49806 "EHLO madara.hpl.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750929AbXBQQHP (ORCPT ); Sat, 17 Feb 2007 11:07:15 -0500 Date: Sat, 17 Feb 2007 08:06:56 -0800 From: Stephane Eranian To: linux-kernel@vger.kernel.org Cc: ak@suse.de, akpm@linux-foundation.org, Stephane Eranian Subject: [PATCH] i386 make NMI use PERFCTR1 for architectural perfmon Message-ID: <20070217160656.GA16715@frankl.hpl.hp.com> Reply-To: eranian@hpl.hp.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.1i Organisation: HP Labs Palo Alto Address: HP Labs, 1U-17, 1501 Page Mill road, Palo Alto, CA 94304, USA. E-mail: eranian@hpl.hp.com X-HPL-MailScanner: Found to be clean X-HPL-MailScanner-From: eranian@hpl.hp.com Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello, This patch against 2.6.20 makes the NMI watchdog use PERFSEL1/PERFCTR1 instead of PERFSEL0/PERFCTR0 on processors supporting Intel architectural perfmon, such as Intel Core 2. Although all PMU events can work on both counters, the Precise Event-Based Sampling (PEBS) requires that the event be in PERFCTR0 to work correctly (see section 18.14.4.1 in the IA32 SDM Vol 3b). A similar patch for x86-64 is to follow. Changelog: - make the i386 NMI watchdog use PERFSEL1/PERFCTR1 instead of PERFSEL0/PERFCTR0 on processors supporting the Intel architectural perfmon (e.g. Core 2 Duo). This allows PEBS to work when the NMI watchdog is active. signed-off-by: stephane eranian diff -urNp --exclude=.git linux-2.6.20.orig/arch/i386/kernel/nmi.c linux-2.6.20.base/arch/i386/kernel/nmi.c --- linux-2.6.20.orig/arch/i386/kernel/nmi.c 2007-02-04 10:44:54.000000000 -0800 +++ linux-2.6.20.base/arch/i386/kernel/nmi.c 2007-02-17 07:59:41.000000000 -0800 @@ -288,7 +288,7 @@ static int __init check_nmi_watchdog(voi * 32nd bit should be 1, for 33.. to be 1. * Find the appropriate nmi_hz */ - if (wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR0 && + if (wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR1 && ((u64)cpu_khz * 1000) > 0x7fffffffULL) { u64 count = (u64)cpu_khz * 1000; do_div(count, 0x7fffffffUL); @@ -685,8 +685,8 @@ static int setup_intel_arch_watchdog(voi (ebx & ARCH_PERFMON_UNHALTED_CORE_CYCLES_PRESENT)) goto fail; - perfctr_msr = MSR_ARCH_PERFMON_PERFCTR0; - evntsel_msr = MSR_ARCH_PERFMON_EVENTSEL0; + perfctr_msr = MSR_ARCH_PERFMON_PERFCTR1; + evntsel_msr = MSR_ARCH_PERFMON_EVENTSEL1; if (!reserve_perfctr_nmi(perfctr_msr)) goto fail; @@ -958,7 +958,7 @@ __kprobes int nmi_watchdog_tick(struct p apic_write(APIC_LVTPC, APIC_DM_NMI); } else if (wd->perfctr_msr == MSR_P6_PERFCTR0 || - wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR0) { + wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR1) { /* P6 based Pentium M need to re-unmask * the apic vector but it doesn't hurt * other P6 variant. -- -Stephane