Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751392Ab3EPJS4 (ORCPT ); Thu, 16 May 2013 05:18:56 -0400 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:58358 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751074Ab3EPJSy (ORCPT ); Thu, 16 May 2013 05:18:54 -0400 Date: Thu, 16 May 2013 11:17:07 +0200 From: Peter Zijlstra To: Stephane Eranian Cc: Ingo Molnar , LKML , "ak@linux.intel.com" , Michael Neuling Subject: Re: [PATCH 3/3] perf, x86, lbr: Demand proper privileges for PERF_SAMPLE_BRANCH_KERNEL Message-ID: <20130516091707.GG19669@dyad.programming.kicks-ass.net> References: <20130503121122.931661809@chello.nl> <20130503121256.230745028@chello.nl> <20130516090916.GF19669@dyad.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130516090916.GF19669@dyad.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2722 Lines: 74 On Thu, May 16, 2013 at 11:09:16AM +0200, Peter Zijlstra wrote: > How about something like the below? It also adds the branch flags Mikey wanted > for PowerPC. The asymmetry is unfortunate, but I think its more useful to have the from kernel branch target than it is not to have it. This way you at least know there was a kernel entry/exit and where you've continued. Without either branch to kernel and branch from kernel entries you'd be wondering WTF happend to your control flow. > --- > arch/x86/kernel/cpu/perf_event_intel_lbr.c | 12 +++++++++--- > include/linux/perf_event.h | 10 +++++++--- > 2 files changed, 16 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c > index d978353..f44d635 100644 > --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c > +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c > @@ -585,17 +585,23 @@ intel_pmu_lbr_filter(struct cpu_hw_events *cpuc) > > /* if type does not correspond, then discard */ > if (type == X86_BR_NONE || (br_sel & type) != type) { > - cpuc->lbr_entries[i].from = 0; > + cpuc->lbr_entries[i].__delete = 1; > compress = true; > } > + > + /* hide kernel addresses if we're not privileged */ > + if (!(br_sel & X86_BR_KERNEL) && kernel_ip(from)) { > + cpuc->lbr_entries[i].from = -1L; > + cpuc->lbr_entries[i].invalid_from = 1; > + } > } > > if (!compress) > return; > > - /* remove all entries with from=0 */ > + /* remove all entries with __delete */ > for (i = 0; i < cpuc->lbr_stack.nr; ) { > - if (!cpuc->lbr_entries[i].from) { > + if (cpuc->lbr_entries[i].__delete) { > j = i; > while (++j < cpuc->lbr_stack.nr) > cpuc->lbr_entries[j-1] = cpuc->lbr_entries[j]; > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index f463a46..7acf1c9 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -77,9 +77,13 @@ struct perf_raw_record { > struct perf_branch_entry { > __u64 from; > __u64 to; > - __u64 mispred:1, /* target mispredicted */ > - predicted:1,/* target predicted */ > - reserved:62; > + __u64 mispred:1, /* target mispredicted */ > + predicted:1, /* target predicted */ > + invalid_to:1, /* @to isn't to be trusted */ > + invalid_from:1, /* @from isn't to be trusted */ > + reserved:59, > + __delete:1; /* Implementation; userspace should > + always see a 0 */ > }; > > /* > -- 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/