From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755514Ab1HKMTO (ORCPT ); Thu, 11 Aug 2011 08:19:14 -0400 Received: from merlin.infradead.org ([205.233.59.134]:36260 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754007Ab1HKMTK convert rfc822-to-8bit (ORCPT ); Thu, 11 Aug 2011 08:19:10 -0400 Subject: Re: [PATCH -tip v3 2/5] perf: change perf_event_header.misc to PERF_RECORD_MISC_USER for BTS From: Peter Zijlstra To: Akihiro Nagai Cc: Arnaldo Carvalho de Melo , Ingo Molnar , Frederic Weisbecker , David Ahern , linux-kernel@vger.kernel.org, Masami Hiramatsu , yrl.pp-manager.tt@hitachi.com, Paul Mackerras Date: Thu, 11 Aug 2011 14:18:46 +0200 In-Reply-To: <20110811120620.5900.50427.stgit@linux3> References: <20110811120555.5900.23642.stgit@linux3> <20110811120620.5900.50427.stgit@linux3> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.0.2- Message-ID: <1313065126.7144.6.camel@twins> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2011-08-11 at 21:06 +0900, Akihiro Nagai wrote: > Change perf_event_headder.misc to PERF_RECORD_MISC_USER for > BTS records, because BTS traces both kernel and user spaces > nevertheless perf specifies to trace only kernel or user space. Now I'm confused.. If BTS traces both kernel and user, the MISC bit should reflect the right state per-sample, on x86 that's easy enough to do by the address. > --- > > arch/x86/kernel/cpu/perf_event_intel_ds.c | 8 ++++++++ > 1 files changed, 8 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c > index 1b1ef3a..323f3f0 100644 > --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c > +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c > @@ -340,6 +340,14 @@ static int intel_pmu_drain_bts_buffer(void) > */ > perf_prepare_sample(&header, &data, event, ®s); > > + /* > + * Since BTS can not trace kernel and user space separately, set Uhm, IA32_DEBUGCTL_MSR.BTS_OFF_{OS,USR} seem to suggest it can?! > + * PERF_RECORD_MISC_USER in header.misc to resolve both kernel and > + * user DSOs and symbols. > + */ > + header.misc &= ~PERF_RECORD_MISC_CPUMODE_MASK; > + header.misc |= PERF_RECORD_MISC_USER; So what's wrong with something like: header.misc |= is_kernel_address(at->from) ? PERF_RECORD_MISC_KERNEL : PERF_RECORD_MISC_USER; > if (perf_output_begin(&handle, event, header.size * (top - at))) > return 1; > >