From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 584D5C433DF for ; Wed, 5 Aug 2020 16:50:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 325AE2067D for ; Wed, 5 Aug 2020 16:50:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="eftEKmga" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728142AbgHEQtr (ORCPT ); Wed, 5 Aug 2020 12:49:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728076AbgHEQsi (ORCPT ); Wed, 5 Aug 2020 12:48:38 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 66197C03461D for ; Wed, 5 Aug 2020 05:57:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Gt9NJuA9NqxmEUokFcw04m2QCDlb3+WQJaB6tPto9FA=; b=eftEKmgaThAuFa0orFvtGPAOiu s8pj8/SncERZwwqVyJQhJ7T2c+Z61TwMviUEWCveyF4i1kyZyfA8uy1LiTvm6llCjAjC6PoIO9Aqx U4j7p+wBzYOO/G+gNMiKJOAADsh2Xbb2XvdbOAODuX/3ovwz0OsGhu7kl+93TvAADgGq/6ZtZQ6jo FQ2Dqvu2Ys1XYrpC2A1gBL+XBkHvPb33oK2xvW7VF+olR5C6Q44hsdi24a4iQWr6dDFZq03+ysi0D s9sPHaTP6sEPY2nVSo4qoNdf08vAMqGe69DUF7K5976e8/Ex2hnMrZyLwETLlHY2PVe8k62sybSKB BJulv18Q==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1k3Iyj-0003Pb-27; Wed, 05 Aug 2020 12:57:09 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 0685F300F7A; Wed, 5 Aug 2020 14:57:08 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id DA00821493853; Wed, 5 Aug 2020 14:57:07 +0200 (CEST) Date: Wed, 5 Aug 2020 14:57:07 +0200 From: peterz@infradead.org To: "Jin, Yao" Cc: mingo@redhat.com, oleg@redhat.com, acme@kernel.org, jolsa@kernel.org, Linux-kernel@vger.kernel.org, ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com, alexander.shishkin@linux.intel.com, mark.rutland@arm.com Subject: Re: [PATCH v1 2/2] perf/core: Fake regs for leaked kernel samples Message-ID: <20200805125707.GC35926@hirez.programming.kicks-ass.net> References: <20200731025617.16243-1-yao.jin@linux.intel.com> <20200731025617.16243-2-yao.jin@linux.intel.com> <20200804114900.GI2657@hirez.programming.kicks-ass.net> <4c958d61-11a7-9f3e-9e7d-d733270144a1@linux.intel.com> <20200805124454.GP2657@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200805124454.GP2657@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 05, 2020 at 02:44:54PM +0200, peterz@infradead.org wrote: > How's this? Clearly I didn't even hold it near a compiler... > --- > kernel/events/core.c | 38 +++++++++++++++++++++++++++++++++----- > 1 file changed, 33 insertions(+), 5 deletions(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 7c436d705fbd..3e4e328b521a 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -6988,23 +6988,49 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs) > return callchain ?: &__empty_callchain; > } > > +/* > + * Due to interrupt latency (skid), we may enter the kernel before taking the > + * PMI, even if the PMU is configured to only count user events. To avoid > + * leaking kernel addresses, use task_pt_regs(), when available. > + */ > +static struct pt_regs *sanitize_sample_regs(struct perf_event *event, struct pt_regs *regs) > +{ > + struct pt_regs *sample_regs = regs; > + > + /* user only */ > + if (!event->attr.exclude_kernel || !event->attr.exclude_hv || > + !event->attr.exclude_host || !event->attr.exclude_guest) > + return sample_regs; > + > + if (sample_regs(regs)) > + return sample_regs; That wants to he: if (user_regs(regs)) return sample_regs; > + > + if (!(current->flags & PF_KTHREAD)) { s/{// > + sample_regs = task_pt_regs(current); > + else > + instruction_pointer_set(regs, -1L); > + > + return sample_regs; > +}